== does a nurse need to expel air from a prefilled flu vaccine ==
== does a nurse need to expel air from a prefilled flu vaccine ==
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Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
Pardon me for being ignorant (BSc in something that probably isn't a science...), but is it possible to fit a fermion into a one-dimensional box? Don't they occupy a (small) volume of three-dimensional space? Or does 'box' mean something else entirely in this context? AndyTheGrump (talk) 04:53, 7 October 2012 (UTC)[reply]
AndyTheGrump: I think our Particle in a box page may help clarify. The use of a conceptual/mathematical solution in one dimension makes the math more tractable, with solutions generalizable to higher dimensions. -- Scray (talk) 17:14, 7 October 2012 (UTC)[reply]
It's analogous to the 3D problem. I think you are working directly in the limit of a large volume, otherwise there wouldn't have been a question about this. In that case, you need the density of states. In general, the number of single particle quantum states for a spin 1/s particle in some large volume V and in a volume of momentum space Vp is given as
2 V Vp/h^n, where n is the number of dimensions. The factor 2 is the spin degeneracy, i.e. it takes into account that for each wavefunction in configuration space, you have two independent spin states. Count Iblis (talk) 15:32, 7 October 2012 (UTC)[reply]
Since Santa needed to get a 2nd mortgage to cover Rudolph's alcoholism treatments, his own Weight Watchers membership, and the cost of human growth hormone treatments for all his helpers afflicted by dwarfism, he was unprepared for the collapse in real estate prices. So, yes, his house is already underwater. StuRat (talk) 04:53, 7 October 2012 (UTC)[reply]
It's sad that with mortgages being in the news so much over the last few years, this really was the first definition of "underwater" that came to my mind. However, my thought concerning it was that the mortgage was probably paid off at least a hundred years ago. Eric (EWS23) 08:54, 13 October 2012 (UTC)[reply]
No, and, generally, warm-blooded animals can't, since it would be difficult to see beyond their own infrared glow, to see, say, the glow of a mouse in some underbrush. StuRat (talk) 06:08, 7 October 2012 (UTC)[reply]
Well, resolved, but I'd add this, from our article cat senses: Cats are able to distinguish between blues and violets better than between colours near the red end of the spectrum. - Nunh-huh22:56, 7 October 2012 (UTC)[reply]
I'm removing the resolved tag; such tags aren't recommended (the recent discussion on the Ref Desk talk page touches on the reasons why). Also, I notice that no one has provided a single source for their statements, which is very disappointing, given that this is a Reference Desk.
Moreover, StuRat's responses are inaccurate and imprecise, at best. There is published literature (some of it, which I've linked below, is both online and free of charge) which reports on the sensitivity of cat's eyes to near-infrared radiation.
Both studies note that the sensitivity of the cat's eye to far-red and infrared radiation is certainly lower than to middle-of-the-visible-spectrum light, but both also demonstrate measurable responses at longer wavelengths. Gekeler et al. go out to 826nm (laser line illumination) and 875nm (IR emitting diode). Speaking from my own personal experience as a mammalian scientist with normal color vision, human beings can certainly see bright sources with wavelengths out into the middle 800's.
Delving a bit further into the question, we can ask what happens at wavelengths that get a bit longer—what happens when you hit 950 or 1000nm (1 micrometer)? Then you start to get stuck by the physical properties of water. Infrared light at 1000nm and longer tends to be strongly absorbed by water, which – inconveniently – is a major component of the vitreous humour that fills the eyeball.
For comparison, that the blackbody emission of a human-body-temperature object peaks way up around 10 micrometers. That's deep, deep into wavelengths strongly absorbed by water (passage through 1 cm of water will absorb 99.9% of infrared light at this wavelength; the eye is essentially opaque to these rays). Forget being blinded by one's own infrared glow—at these wavelengths one is blinded by the opacity of one's own eye. TenOfAllTrades(talk) 02:29, 8 October 2012 (UTC)[reply]
I think it's further worth noting that, at least in snakes, sensation of IR is not done by the eyes, but by specialized "pit" organs. Also, in snakes, there is no specific reception of IR wavelengths. Rather, the pits are structured in a way that crudely focuses radiant heat onto nerve endings that are actually sensing temperature. Someguy1221 (talk) 02:57, 8 October 2012 (UTC)[reply]
It may also be worth pointing out, in regard to StuRat's answer, that infrared is quite a wide spectrum. If, for example, cats were able to see one-micron light, that would be well into the near infrared range by almost anyone's standards, but there would be hardly any glare at all from the cat itself. Presumably Stu was talking about much longer-wave infrared, say around ten microns. --Trovatore (talk) 05:15, 8 October 2012 (UTC)[reply]
My point was that IR detection at useful wavelengths (ones that would allow them to see warm-blooded predators and prey) would be difficult due to their own glow at those frequencies. IR at other frequencies doesn't appear to have any advantage to a cat over visible light. StuRat (talk) 21:12, 8 October 2012 (UTC)[reply]
Cat's and humans use the same proteins and mechanisms to see the longer wavelengths from the visible spectrum, just as most animals, so there will be little difference between them. The ability to capture more light will also help in seeing some near infrared, but I don't think they can see longer wavelengths than humans can (although humans may require higher intensity levels). There doesn't seem to be a protein or other biological mechanism that makes it possible to see much longer wavelengths than 850nm. Porphyropsin might add slightly to the range, but other than that, I don't know any.
In the UV range, there will be much more diversity, since the higher the frequency of the light is, the more chemical and biochemical mechanisms exist that can be influenced by it.
As Someguy1221 points out, the IR vision in snakes is based on temperature sensing, not direct IR vision. The pit organ's reflectivity in the visible spectrum is very high, had it not been, it would also detect visible light, and be useless to the snake I presume. Ssscienccce (talk) 21:12, 8 October 2012 (UTC)[reply]
I've tested my color-vision range with a spectroscope some time ago, and found out that I can see even faint IR sources at wavelengths of up to 800 nm at least (to me, they appear a dark reddish-brown). Does this mean that I'm a cat? ;-) 24.23.196.85 (talk) 02:31, 10 October 2012 (UTC)[reply]
It doesn't have a permanent dipole but its electron density map (why can't I find a basic electron density map of it online?) would be strongly polarised, with the carbonyl oxygens retaining most of the electron density and the carbonyl center being electropositive. Yet why doesn't carbon dioxide remove some of the slightly polar flavor compounds that are found in caffeine (CO2-water partition coefficient at least 0.3?) ? It has some polarity, right, just not dipolarity. 71.207.151.227 (talk) 16:35, 7 October 2012 (UTC)[reply]
This is a quadrupole. This is not what CO2 looks like. No, it has no polarity. A "quadrupole" would look like the pic I am appending. Think of it this way: the two diametrically oppose oxygens are pulling electrons equally from each other across the carbon atom. That creates a roughly equal distribution of electrons across the whole molecule. In general, any molecule which shows perfect VSEPR symmetry (i.e. one of the basic 3 VSEPR shapes: linear, trigonal planar, or tetrahedral) will be perfectly non-polar, so long as every point is the same atom, like CO2 where both atoms attached to the central atom are oxygen. This is true even where there is a large difference in electronegativity among the individual atoms, because those electronegativity differences will, in essence, counteract each other. So even molecules like tetrafluoromethane show the same nonpolar character as methane; CF4 and CH4 have comparable melting and boiling points because they are equally nonpolar, the difference is explainable by differences in London dispersion forces due to the difference in molecule size. --Jayron3218:46, 7 October 2012 (UTC)[reply]
Apparently the quadrupole moment of carbon dioxide is -4.1 x 10-26 e.s.u.,[1] considerably stronger than that of nitrogen, hydrogen, and methane, which (hopefully) can permit its separation from exhaust by certain three-dimensional porous structures intended to mitigate greenhouse emissions.[2]Wnt (talk) 21:28, 7 October 2012 (UTC)[reply]
See [3]. We are on a parallel evolutionary path with monkeys, not direct descendents from them. Our common ancestors are all extinct. StuRat (talk) 22:59, 7 October 2012 (UTC)[reply]
Well, even if our common ancestors are extinct, they still could be called 'monkeys.' BTW, I am afraid the graphic you linked to is not the evolutionary perspective, but just the present day classification. OsmanRF34 (talk) 23:32, 7 October 2012 (UTC)[reply]
I would interpret StuRat's linked diagram to mean "yes". While it is true that the early ancestors of monkeys and apes, living at a different time than the present and not being a member of any modern clade, might be called whatever we wish, still, it seems logical to call the single common ancestor of "New World monkeys" (Platyrrhini) and "Old World monkeys" (Catarrhini) a "monkey". The catch there is that "monkey" is not a monophyletic group, since it includes a subgroup of "apes" that by tradition are not called monkeys, and if you're not defining it monophyletically, you can define it a lot of ways - for example, you could define it to include every one of the individual subgroups but not the common ancestor. But I think that's a stretch. Wnt (talk) 00:51, 8 October 2012 (UTC)[reply]
Biologists use precise terminology to avoid getting bogged down in semantic issues like this. A biologist would say that we are descended from animals that belong to the group simiiformes, which includes monkeys and their ancestors. Most biologists when speaking informally would probably apply the term "monkey" to everything in simiiformes, but there is no official rule governing this. Looie496 (talk) 00:50, 8 October 2012 (UTC)[reply]
Apes, including Humans, are Catarrhines. Our common ancestor with the Catarrhine monkeys would be itself considered a catarrhine monkey. Its common ancestor with the platyrrhine monkeys would also be considered a monkey. Yes, we are descended from some animals which, if they were living today, would unambiguously be considered monkeys. μηδείς (talk) 04:10, 8 October 2012 (UTC)[reply]
I am stuck on this physical chemistry question and would really appreciate some help. Here goes the question
Many processes such as the fabrication of integrated circuits are carried out in a vacuum chamber to avoid reaction of the material with oxygen in the atmosphere. It is difficult to routinely lower the pressure in a vacuum chamber below 1.0 * 10^-10 Torr
A) Calculate the molar density at this pressure at 299K
Well this is just simple substitution: P = ρ R T where ρ is the molar density
ρ = P/RT
= 1*10^-10/(299 * 62.36)
= 5.36 * 10^-15
B) What fraction of the gas phase molecules initially present for 1.0 atm in the chamber are present at 1.0 * 10^-10 Torr?
This is the tricky part. I know that PV = nRT and when you lower the pressure from 1.0 atm (760 torr) to 1.0 * 10^-10 torr, and assuming that V and T are held constant, n is lowered as well. Since molar density is defined to be the number of moles over volume
State 1 = 760 torr
ρ1 = n1/V = P1/RT = 0.0407
State 2 = 1.0 * 10^-10 torr
ρ2 = n2/V = 5.36 * 10^-15
The ratio of n1 to n2 can be calculated by dividing ρ1 by ρ2 which equates to 1.32 * 10^-13.
The online homework system is telling me that my answer is wrong and I am just trying to figure out what I did wrong. Any help is appreciated! Thanks in advance! — Preceding unsigned comment added by 169.232.236.95 (talk) 23:03, 7 October 2012 (UTC)[reply]
I worked it out without looking at your method, and got the same answer as you (1.322 x 10-13). Does the online system give you their numerical answer? If you can post that, we might be able to spot a mistake they made. Ratbone124.178.60.218 (talk) 00:25, 8 October 2012 (UTC)[reply]
Remembering a similar problem with a computer program checking answers some time ago, maybe you should try giving the answer as 10-10/760 or 10-11/76 instead of the rounded off result. Ssscienccce (talk) 21:32, 8 October 2012 (UTC)[reply]
I've never seen an automatic physics or chemistry homework checker that wanted a raw fraction when asking for something that can be solved as a numerical value. As far as rounding though, I have seen several that only accept an answer as "correct" if it is the proper number of significant figures (as well as numerically correct obviously). DMacks (talk) 21:46, 8 October 2012 (UTC)[reply]
Credit to StuRat who taught me. @DMacks: Maybe the programs are getting better? I remember how much my teachers disapproved of rounded off results when the answer could be presented by a short, simple expression like a fraction or square root. Ssscienccce (talk) 08:24, 10 October 2012 (UTC)[reply]
They probably are. All secondary school students (in the UK) these days tend to have calculators which are capable of giving answers as fractions and even surds. You have to be more cunning about testing for true understanding, where you used to have the lazy option of simply requiring exact answers (when calculators would only give a decimal approximation). It causes me a moment of wonder, every so often, that they all carry these little things that display such answers.. 86.159.77.170 (talk) 19:47, 11 October 2012 (UTC)[reply]
I have not been very impressed with automatic checking programs so far. It seems as though they are doing a character comparison with a small list of allowed "correct" answers. So, if the answer is supposed to be exactly "0.48", you have to rely on the person who entered the allowed answers having entered both ".48" and "0.48". If not, one will be marked wrong. Then, when you add in the possibilities of answers like "48/100", "24/50", and "12/25", those would each have to be supplied to the program as correct answers, too, as would scientific and engineering notation. The result is that you can spend more time trying to guess what format(s) are allowed for the answer than actually doing the problem. StuRat (talk) 00:47, 14 October 2012 (UTC)[reply]
October 8
Accuracy of forward looking economic statements
There are many cases were businessmen, economists, and similar people have to predict what the market is going to look like for their product weeks, months, or even years in advance. For example, farmers hope to plant crops that will give them a good profit come harvest time. Or alternatively, a book publisher tries to predict demand when deciding on the size of a print run. In some cases there are robust futures markets to help, in other cases in-depth business studies might be undertaken, but often such predictive judgments seems to boil down to some expert's personal opinion. I'm looking for materials I might read reviewing the successes and failures of such forward looking economic statements. For example, when experts predict that the GDP will increase over the next 12 months, how often are they right? Do the target prices set by stock market analysts have predictive value? Etc. Also, I would like to read about cases where detailed mathematical modeling has been applied to economic problems, and where such models have tended to do well or poorly. Thanks for your help. Dragons flight (talk) 11:29, 8 October 2012 (UTC)[reply]
I have no answer to the general question, nor, unfortunately, references. But one of the first scientific meetings I attended (back in 199X as a student) was a local meeting of machine learning researchers. Two or three groups had tried to predict stock prices from past performance, and their analysis seems to agree that the past data has essentially no predictive value. I don't know if that is still the state of the art, and I know even less how this applies to more macroscopic questions. --Stephan Schulz (talk) 12:04, 8 October 2012 (UTC)[reply]
I recall reading a review of a book on just this subject... I believe it was this one. The book's conclusion, and the conclusion of many other studies, is that experts have a positively lousy track record for accurately predicting the future broadly. You might check out the book, though. --Mr.98 (talk) 14:59, 8 October 2012 (UTC)[reply]
A well-received book with a similar theme is The Black Swan (as well as the author's earlier book Fooled by Randomness). They're not going to have comprehensive data about what you seek, but rather selected examples to further the author's argument (basically that predictions of the future are worthless). Buddy431 (talk) 23:01, 8 October 2012 (UTC)[reply]
At one stage in my career, I worked in the planning group of a large governemnt department, making decisions on the provision on capital infrastructure. This involved working out the Net Present Value (see http://en.wikipedia.org/wiki/Net_present_value), and applying Jacobson Provisoning Theory. JPV is a mathematical theory that tells you what size increments to install to meet a requirement that grows over time in order to minimise the cost, for example the provision of hospital beds in a city whose population is growing. You could build in one big project that meets growth requirments for twenty years and get econoimies of scale, or build say every two years another ward. JPV tells you which costs less. Much infrastructure can only be planned on a long term basis, 10 or 20 years.
The point is, both NPV and JPV require a prediction of demand growth, interest rates, and inflation in order to make any sense. We used to get a yearly report from Treasury that predicted these things. Generally, they gave upper and lower limits at a certain level of confidence, for intervals 1, 2, 5, 10, and 20 years out. Experience showed that their predictions within thse limits were very good, with certain exceptions I will describe below. Naturally the limits got broader as the time frame increased. My experience is Australian, but if Australia could do it, other advanced countries can too. These reports were not made public when published, but would be available from National Archives.
Economic predictions released to the media by certain "experts" are far far less reliable, as they don't have the resources, and often use cheap data of dubious value, such as the number of job adverts printed in morning newspapers.
Treasury ecomonic predictions generally made an assumption that the government of the day would remain "competent", and say something like "we expect the politicians to take this reasonable option, or possibly that option, and factored this in when estimating the upper and lower limits." Mostly, Australia has had "competent" governments - the sort where the political leaders took advice from the public service. An example from Australia is the Menzies Govt (conservative) in the 1950's and 1960's. At other times we've had "incompetent" govts, where political leaders assume the public service is not to be trusted. This can lead to reform, but makes new economic predictions very difficult, and existing predictions incorrect. The 1970's Witlam Govt (Labor) is an example. More recently, we've had political leaders that intelligently challenge the advice from the public service. The Keating Govt (Labor) is an example. This is the best form of government in all respects and allows reasonably good economic predictions.
Things like war breaking out, oil crises, can ruin any prediction.
It's more difficult now than it used to be. Today's politicians don't have the intellect of earlier leaders, and tend to go more on ideology than on facts or reasonable inference. Also, economies used to be quite regional, but economies are now strongly linked globally. For example, Australia and the USA used to be largely industrial - with large numbers of folk employed in factory production of all kinds. This makes things controllable. Nowadays, factory production is not the great employer - the service industries are. This makes things unstable. Education standards are falling. As less well educated thinkers enter the workforce, things will get even more unstable.
See Efficient-market hypothesis. This theory, which has had a lot of holes poked in it but still is considered to have a large element of truth in it, says that as soon as any information relevant to the appropriate price of a particular stock, or to the level of the stock market as a whole, becomes available, it is instantly incorporated into the stock price; any trades that take place after the info becomes available will take place at the newly appropriate price. So no one can beat the market unless they can obtain or predict new information before it becomes generally available to stock traders. In the absense of insider trading, this is tough, though lots of investment advisors are in the business of trying to do it. But studies show that none of them consistently beat the market -- at any given time, someone is beating the market, but later on it's someone else who's beating the market. So the answer is no, stock market forecasts and forecasts of individual stock prices are no better than throwing darts at a dart board, and the above is the theoretical reason for that. The classic book on this is Burton Malkiel's A Random Walk Down Wall Street. Of course an infinite amount has been argued this way and that way about these ideas over the years, such as questioning why the market as a whole didn't see the recent financial crisis coming (in which case the bubble would never have been allowed to grow in the first place, and therefore there would have been no bubble to burst).
A claim often repeated on the internet is that the Great Pyramid at Giza could not be reproduced with today's technology. It is aligned to true north with a greater degree of accuracy than any modern building and we could not match or better it. The quality and accuracy of the stonework is beyond anything that could be done today, even with today's modern tools and equipment.
I just cannot believe that this is true. The sort of website this appears on is usually to do with the paranormal and that fact that the pyramids must have been built by Alien's etc - yet it even appears on some more "reputable" sites.
Another claim is that Giza is located at the precise geographical centre of the earth's landmass and the chances of the pyramid being located there are billions to one. I have researched and debunked this particular gem - how do you find the centre of the surface of the sphere???? — Preceding unsigned comment added by 195.188.208.251 (talk) 11:52, 8 October 2012 (UTC)[reply]
That last one is more appropriate to the math desk, I guess. However, the claim is not "the center of the surface of the sphere", but "the center of the landmass". Land is distributed unevenly over the surface of the earth, so there is an asymmetry that can be used to define a "center" (of course, for most definitions there would be two, one on either side of the earth). Given that there are plenty degrees of freedom for defining "land" (what about floodplains? Do mountains count more than plains? What about the dead sea?) and "center", it's probably easy to come up with a formula that places the pyramids (well, one point in their vicinity) in the center. --Stephan Schulz (talk) 12:31, 8 October 2012 (UTC)[reply]
I found [4] which indicates that the center of mass of the upper layer of the Earth is displaced 29.0 km toward 15.4 N, 150 E ... which looks like the middle of Mariana Trench. Am I reading this backwards? Admittedly I haven't figured out quite what I'm really reading about here as of just yet... they even talk about a "magnetic center". Wnt (talk) 14:46, 8 October 2012 (UTC)[reply]
Presumably, they mean "land area", as in areas where the land and is above sea level. The center of that should be above the equator. If you neglect the Americas, it should be further East. So, perhaps, including the Americas, that might bring it back into Africa. However, the Earth, being round, brings up the question as to whether a pocket of land near the opposite side draws the center of mass towards it, on whichever side is closest, weighted 100% for that area, or whether the area weighting is reduced to account for it "pulling from both sides". You can also find the CG point in 3D, putting it near the Earth's center, then project it back up to the surface, normal to the nearest surface. This seems like the best approach, to me. StuRat (talk) 19:40, 8 October 2012 (UTC)[reply]
Where do you slice open the earth and how do you spread it out on a flat surface to define the center of any subset of it? --Jayron32 19:44, 8 October 2012 (UTC)Edit: Stu made a clarifying point here which renders my question somewhat silly. When he originally made his statements, it was unclear what he was defining. It's clear now, and my question is now moot. --Jayron3219:48, 8 October 2012 (UTC)[reply]
(ec with Jayron's addition above) I don't think you need to. Aside from the method I listed above, another would be to try every point on the surface of Earth, and for that point find the weighted great circle distance to each bit of land. I could easily write such a program, if I had a file with, say, each square kilometer's longitude and latitude numbers, along with the percentage of land above water (smaller resolutions would make the program really slow). You would want to first look at large intervals, let's say a point every 30 degrees of longitude and latitude, then look at a smaller interval, say a point every 10 degrees of longitude or latitude, around the previous best result, etc., until you get an answer of sufficient accuracy. StuRat (talk) 19:53, 8 October 2012 (UTC)[reply]
Our article Great Pyramid of Giza gives numbers for the precision of its construction. The sides of the base are over 230 meters long and have an average error of 58mm. The base is horizontal and flat to within 15mm. The finished base has an average alignment error (from true north) at the corners of 12 seconds of arc. Those numbers are very impressive for such an huge and ancient construction, but I can't see why we wouldn't be capable of reaching the same accuracy today. I can't find good references for the tolerances of large modern buildings, probably because the accuracy in placement and construction simply isn't noteworthy. 209.131.76.183 (talk) 14:55, 8 October 2012 (UTC)[reply]
For what it's worth, most modern construction uses a tolerance of about 1/4" in 10 ft (less than 1 cm in 3 m), non-cumulative, for everyday work, and greater accuracy can be attained at extra cost, bearing in mind that settlement, thermal expansion and loading can and will have effects (though the latter two are probably inapplicable for a pyramid). I don't see the challenge of layout to the observed standards as beyond the means of an early civilization which chooses to devote the appropriate resources. Acroterion(talk)15:06, 8 October 2012 (UTC)[reply]
We can compare that to the Channel Tunnel. The length of each bore is 50.45 km (per that article). The Institution of Civil Engineers' book The Channel Tunnel (ISBN 9780727719225) p54 says the two bores for the service tunnels (the first to meet) were off by "4mm vertically and 15mm horizontally". -- Finlay McWalterჷTalk15:10, 8 October 2012 (UTC)[reply]
The precision of construction is remarkable, but not unearthly. I should note that Thuban was, in 2787 BC, quite a reliable pole star, less than 2.5 arc-minutes away from true north. But by 200 years later it would have been a full degree from the pole, so presumably the people laying the lines of stones would have had to watch its circling quite carefully to come within 4 arc-minutes. I wonder if, at the time, they derided their efforts as a sloppy job, wistfully remembering the stories of the constant pole-star of a bygone age? I assume they had a choice of many stars to watch coming up from the east to use to align the sides going in that direction. The levelling is another question - if it rained on the base of the pyramid, how accurately could you level it based on which way it flows? (Though the Sahara was apparently 'as dry as it is today' by 3400 BC, so maybe they had to flood it by hand?) Wnt (talk) 16:54, 10 October 2012 (UTC)[reply]
Aviation-related question on the humanities desk.
I'm taking the liberty to cross-post, because there may be someone knowledgeable here, who does not usually read the humanities desk. The question is Bob Hoover anectote - Urban legend? If someone has information relevant to the question, please answer at the humanities desk. Thank you. --NorwegianBluetalk12:23, 8 October 2012 (UTC)[reply]
de-salting urine
In the lab where I work, we sometimes do thin-layer chromatography on urines. Part of the prep is to "de-salt" the urines by adding propan-2-ol to a small amount of the urine, and then freezing these preparations for at least one hour before using them. What I would like to know is:
what does it mean to "de-salt" urine? What's happening?
How does propan-2-ol achieve this? What are its properties that make it work?
Found an even better one. This page explains why salt, freezing, and isopropanol are all used in preparation of a DNA sample. I assume most of these techniques are used for Gel electrophoresis rather than TLC, but there is likely a similar rationale. --Jayron3218:14, 8 October 2012 (UTC)[reply]
It would be easier to answer this if I knew what compound(s) you were trying to isolate. There are many different reasons that could come up. From [5] I see that one reason is that during liquid-liquid extraction, stable emulsions can occur, which "might be overcome by either an increase of the phase ratio (organic/aqueous), or saturation with neutral salts, or freezing of the aqueous phase, or the application of supported LLE (adsorption of the aqueous phase on diatomaceous earth before extraction with water immiscible organic solvent)." Extractions of this type are a bit of an art, devised by trial and error, usually by frustrated postdocs or grad students who will do whatever comes to mind trying to get a procedure to work this week rather than next, which will then be followed religiously (by which I mean, by rote and without critical thought) by what may be literal generations of future researchers. (If you think I'm kidding, you should search "rubidium chloride" sometime) [6]
If the above source is the application you're thinking of, then its role there is very different from in DNA extraction. For DNA, the idea is that when you have a less polar solvent, the highly charged phosphates that make up the DNA backbone will find some nice positive ion someplace to snuggle up with, and bring it out of solution in big white lumps. The excess salt is simply washed out with 70% ethanol later on, because the DNA is huge and won't dissolve in ethanol, especially once you've compressed it up against the wall of a centrifuge tube at high g-forces, but the salt can. But for resolving the emulsion, you're trying to make it so that the bits of aqueous and of organic in a mixture will fuse together. (Actually, emulsions aren't a topic that I understand very well; but you can see from this much that it must be different from what you do to DNA) Wnt (talk) 05:55, 9 October 2012 (UTC)[reply]
Thanks for the answers so far. I had a look at the links provided by Jayron and they didn't really help, because DNA extraction is a very different thing. The TLC I'm doing is for sugars in urine; glucose, sucrose, fructose and such. I'm aware that this is quite a common application, but most of what I've found on the web assumes a basic level of understanding, or just says, "this is what works" without making an explanation as to why. I know that desalting helps give clearer streaks, less 'clumpy' interference I suppose, but wondered if there were also other reasons, perhaps dropping out of solution some compounds that would coelute. I also wondered if propan-2-ol does some deproteinising as well (based on the sometimes rather large pellets after centrifuging). Sternenjägerin (talk) 07:06, 9 October 2012 (UTC)[reply]
Without more details, it's hard to guess what's going on. First hit I got for "desalting urine TLC" mentions drying the urine first (evaporating off the water). There's a huge difference between a salt-sugar-isopropanol mixture with water and one without. Salt will separate a water-isopropanol solution, salt solubility in water and in isopropanol decreases at lower temperatures, freezing water will drive out salt, freezing a water-isopropanol mixture is fractional freezing; Sugars dissolve in isopropanol, salt to a lesser extend. All these may play a role, but without more information, I can only guess. Freezing for at least one hour doesn't make much sense imo, not much can happen when everything is frozen. Slow freezing, partial freezing and cooling down a liquid on the other hand have many uses. If we're talking about a waterless mixture, you may drive out the remaining salt by lowering the temperature and with it the solubility, a better alternative to using cold isopropanol in the first place because that would make the dissolution of the sugars unacceptably slow and you'd get water condensation from the air. Ssscienccce (talk) 13:22, 10 October 2012 (UTC)[reply]
If you can link any of those things you found on the Web that detail the basic procedure it will be a lot easier to figure out what they're talking about. Wnt (talk) 16:36, 10 October 2012 (UTC)[reply]
This sounds like part of a homework problem on exponential growth. Is there anything in particular about the problem that you are having trouble understanding? 209.131.76.183 (talk) 19:51, 8 October 2012 (UTC)[reply]
You formula is (C)2i, where "C" is the number of cells initially, and "i" is the number of time increments, with doubling occurring at each time increment. However, note that doubling at that rate can't happen for long, as soon the resources the cells need will be used up and they may also poison (or eat) each other. StuRat (talk) 22:15, 8 October 2012 (UTC)[reply]
You could keep it going a bit longer that way, but soon the petri dish would overflow, as would the barrels, vats, and tanks you moved them to next. StuRat (talk) 03:58, 9 October 2012 (UTC)[reply]
Correct. If we double the population with each cycle, we end up with over a thousand times the initial population in 10 cycles, a million times in 20 cycles, a billion times in 30 cycles, a trillion times in 40 cycles, etc. StuRat (talk) 21:22, 12 October 2012 (UTC)[reply]
Depends on how long a minute is. You can still calculate 2^x based on a given x. The question seems to be at about a fourth or at the most fifth grade level. μηδείς (talk) 02:48, 9 October 2012 (UTC)[reply]
Bugs & Stu, I am fairly certain Looie meant doubling can't happen at the rate of a minute because mitosis takes on the order of an hour to repeat; one source says (without specifying if they mean time to occur or to repeat) of 8 minutes in a fly embryo and 20 minutes in bacteria. (Hence my cryptic remark as to depends how long a minute is.) Also, the early stages of cell division in human embryos don't include growth, so the many-celled embryo when it implants is the same size as the egg when it is fertilized. μηδείς (talk) 01:48, 12 October 2012 (UTC)[reply]
To save others the trouble, neither TinEye nor Google reverse-image-search yields much of interest for this image, bar its Kew page and some mirrors and Pinterest-pins of it. It seems that the name Honzo Zufu simply means "plants illustrated" (the name of the work from which this illustration comes), and Kew (et al.) simply calls it "blue flowers". -- Finlay McWalterჷTalk22:23, 8 October 2012 (UTC)[reply]
That sounds cool, how does one do a reverse image search? (BTW, a google search for blue flower is also pointless, and yields mostly falsified images.) μηδείς (talk) 01:47, 9 October 2012 (UTC)[reply]
No luck at the language desk, thanks to Kagetora. It does look somewhat like a peony, but according to our article they are red, yellow or white. Also, the little yellow heads make it look like a member of the Compositae, but peonies are in the Saxifragales. Peonies do have yellow anthers, but they are elongate, not spherical. μηδείς (talk) 06:28, 10 October 2012 (UTC)[reply]
It might still be enlightening to know what the Japanese inscription says. The images at look pretty similar. The blue colour is just artistic licence. Peonies used to be Ranunculaceae and the image does shout that out. Paul venter (talk) 20:46, 10 October 2012 (UTC)[reply]
I don't think you can suggest the blue color is just artistic license, given the book is a medicinal, and the text according to Kagetora's comment at the lang desk mentions the blue color. Also, the leaves as depicted are sessile and simple, while the peony's are petiolated and compound. μηδείς (talk) 02:27, 11 October 2012 (UTC)[reply]
KägeTorä interprets it as 'purple' rather than 'blue' - so perhaps the blue colour was more of a printer's gremlin than a colour that reflected reality - herbals get that a lot. Paul venter (talk) 06:13, 11 October 2012 (UTC)[reply]
(Yes, my previous post said "blue color' before KageTora had offered his reading of murasaki as purple.)
Japanese splits up color space slightly differently from English. The term aoi covers a range including colors we consider blue and green. That murasaki is usually translated as purple doesn't necessarily mean it doesn't also cover indigo, which is the word I would use to describe this flower's color if I wanted to be more specific than blue. (Indeed, ROYGBIV has the two colors indigo and violet that overlap in the purple range, while Russian, for example, doesn't even have a single basic word that covers the blue range in the English sense. It has голубой, (goluboi) light blue, and синий, (sinii) (darker) blue, which are considered separate basic colors in the way we consider green and yellow separate basic colors.) μηδείς (talk) 17:01, 11 October 2012 (UTC)[reply]
My expert on NE N. Am. plants agrees with my opinion that it looks like a member of the compositae but has no better guess. The big problem is that we can't see into the center diagnostic part of the flower to tell if the yellow things are sexual parts (anthers) as they would be if it were a peony, or actually little separate flower heads in a big composite like they would be in a daisy or a mum. The leaves, which are depicted as simple, dentate, opposite and sessile, rule out a peony.μηδείς (talk) 01:20, 12 October 2012 (UTC)[reply]
I asked at a forum in Japan and got this database link. See this image. It's a different version, but the description is same. 千葉 is Chiba. 鋸 is a saw or this might be Mount Nokogiri (Chiba). 紫 is purple. The sentence could be "Found purple one at Mount Nokogiri, Chiba" or "Found saw-purple one in Chiba". 紫色淡紫色ノ物 means "Purple and pale purple colored one". The other flowers on the pages before and after are poppies. Someone in the forum said it was P. somniferum var paeoniflorum. The Japanese name of the flower is 牡丹芥子/peony poppy. I'll call u-tokyo and asked for details. If they are kind and answer my questions, I'll post the information here. Oda Mari (talk) 05:30, 12 October 2012 (UTC)[reply]
I had found a database at National Diet Library before I asked at the forum, but could not find the image as there were too many images. As I knew which volume to look up, I found this one, the same version of ours. I noticed the description was different. It says 鋸歯/serrate leaf. I think this description is the correct one. This page says it's piony poppy. The flower is definitely P. somniferum var paeoniflorum. According to the description of the book, it's not wood block print, but a manuscript (1844). As for u-tokyo, I have to e-mail for inquiries, but I don't think the inquiry is needed anymore. Oda Mari (talk) 08:17, 12 October 2012 (UTC)[reply]
Lovely bit of detective work! Poppies before and after our plate surely clinch the ID. Thank you for the effort and interest! Do wish I could read Japanese! Paul venter (talk) 09:08, 12 October 2012 (UTC)[reply]
Ah, yes, brilliant, it is quite obvious from the leaves and petals it's a poppy. The little yellow spheres inside the flower are quite inaccurate depictions of the ring of elongate yellow anthers. But still very interesting. μηδείς (talk) 17:46, 12 October 2012 (UTC)[reply]
this is half psychology and half science breakthrough question. the psychology question follows.
is it possible to build time viewing machine to very distant past by finding a shorter path light takes around massive objects and following short cut catch up with it and view very distant path through powrful megascopes?
secondly isn't your opinion of the science validity of this question greatly improved by reference to this stupid meme - http://www.quickmeme.com/meme/3r8eie/ - which is far less useful, as it does not describe how someone might get the distant past image back to earth to view. whereas, finding a tortuous light path that ends up near us is much more likely.
followup question:
- is anything shiny enough and millions of lightyears away to reflect even a single photon from earth back to earth, today? if so, then is even a single photon hitting earth on average of once per year that shows earth from the dinosaur era? — Preceding unsigned comment added by 80.98.245.172 (talk) 21:59, 8 October 2012 (UTC)[reply]
A photon would be not so much reflected by a mirror as deflected around a massive object, like a black hole. It's possible a few "dinosaur photons" from long ago might return to Earth, however, the problem is the signal to noise ratio. That is, how would we know which photons are from dinosaur Earth, versus the huge number of photons from other sources ? And, even if we could identify them all, I doubt that there would be enough to see anything from them. StuRat (talk) 22:10, 8 October 2012 (UTC)[reply]
(ec)First, please don't post in all caps; it is the internet equivalent of shouting and is generally harder to read (I have altered the text to lowercase). For the first question, yes, in principle, a telescope can act as a "time viewing machine", and if you throw out engineering limitations, a telescope plus a distant mirror could let you observe Earth millions of years ago. However, you can't see anything prior to the point when the mirror was constructed, so unless we find giant space mirrors floating around, we can't actually see anything on Earth before now (though we could allow our descendants to see us now, or as soon as we build said mirror). A gravitational lens could, in principle, act as such a mirror, but there are no suitable candidates (plus all those engineering limitations re-emerge as soon as you want to talk about actually doing something). For the last, there is no super-shiny space mirror out there, so far as we know, but it wouldn't be unreasonable to expect photons to return after some arbitrary number of usual reflections, etc -- though anything meaningful will be long-since lost in the noise. — Lomn22:16, 8 October 2012 (UTC)[reply]
Quibble: You could view things reflected from Earth, at twice the age of the distant mirror, all engineering considerations aside. StuRat (talk) 22:24, 8 October 2012 (UTC)[reply]
Since the Apollo moon landing program, scientists have been able to see backward about 2.6 seconds at least so far as determining that a laser beam was transmitted to bounce off the [[Lunar Laser Ranging experiment] installed then on the Moon. In principle, if not in practice, if a flat mirror many kilometers in diameter were built on the Moon, couldn't we see images of what happened 2.6 seconds ago? A large enough mirror on the Moon might allow a Hubble quality scope in near Earth orbit to see an object 400 meters across on the Earth 2.6 seconds ago, judging by an article on aiming Hubble at the Moon, and doubling the distance.. I expect the cost of such a mirror to provide even 400 meter resolution of events 2.6 seconds ago would be staggering, but (again only in principle) couldn't a mirror farther away allow a 1 hour or 1 day (or any particular period) retrospective view of Earth? How big would the mirror have to be for the system to function? Would making the mirror concave like a long focal length telescope mirror help? A quick calc implies that with Hubble, if the mirror were 1000 times the Moon's distance, it could see 2600 seconds (43 minutes) into the past, but the resolution would only be 400 km. A bigger telescope could improve the resolution. Just sending the telescope to the remote point to look back at Earth would likely be cheaper than putting a giant plane or convex mirror far from Earth. A more practical way to view our past (fuzzily) is when a distant spacecraft looks back at Earth , like Pale Blue Dot when Voyager 1 took a picture (if a pixel is a picture) and sent back an image of how the Earth looked 11 or so hours earlier. If we built a humongous and impractical mirror in space to reflect back light to a nearby star, it would in principle let them see themselves as they were, if they built an impractically large telescope. Such reciprocity would get around the need to wait eons for our own space telescope to get lightyears away from Earth. Edison (talk) 00:28, 9 October 2012 (UTC)[reply]
October 9
Yearly hours of sunlight at different latitudes
Do I understand rightly that all locations worldwide receive an equal number of hours of sunlight in a year? I'm ignoring clouds for the moment, along with shade from mountains and other factors that vary from place to place at the same latitude. I found this discussion, but (1) I can only read part of the page; and (2) the guy who drew the diagram seems to be saying that night and day are also equal, and I know that's wrong because the Sun is a disc, not a point. Nyttend (talk) 02:46, 9 October 2012 (UTC)[reply]
It's almost true. If the Earth's orbit around the sun was a perfect circle, every point on Earth would see the sun exactly 50% of the time, averaged over the whole year. But the Earth's orbit is actually slightly elliptical, so there are small differences. I am ignoring the disk-shape of the sun -- that's a very small factor, along with some others such as the curvature of the Earth. Looie496 (talk) 04:11, 9 October 2012 (UTC)[reply]
Also note that this doesn't mean every place on Earth receives the same magnitude of sunlight, as, near the poles, the Sun is always low on the horizon, and hits at a shallow angle, after going through more atmosphere. So, a solar panel at the poles is not very useful, compared with the equator. StuRat (talk) 04:16, 9 October 2012 (UTC)[reply]
lightning
Does lightning go through closed windows? Is it safe to be on a computer during lightning? If lightning strikes a body of water, how far away does it travel? — Preceding unsigned comment added by 173.22.168.103 (talk) 02:49, 9 October 2012 (UTC)[reply]
Our Lightning strike article may be of help here. Regarding your particular questions, though glass is a good insulator, the window frame and surrounding structure will probably not be, I doubt that shutting the window will reduce the risk, but you are almost certainly safer inside a building than outside. As for computers, anything connected to the electricity mains or to a phone line has a chance of being zapped by a strike outside being conducted through the wires - though it is probably more likely to damage the computer than the user. As for lightning strikes onto water, I'm not sure. In any case, though lightning is dangerous, there are precautions that can be taken, and fatalities are relatively rare. AndyTheGrump (talk) 03:50, 9 October 2012 (UTC)[reply]
The danger of being on a computer is mainly to the computer. If your computer is plugged into a power strip with a surge protector, there shouldn't be much risk, though. If your computer isn't plugged into a power strip, it ought to be, if you value your computer.
I don't think a urgesurge protector would do much good if your house was struck by lightning, but that's rare, as was previously said. StuRat (talk) 04:17, 9 October 2012 (UTC)[reply]
Lightning could strike a pole-mounted transformer that leads to your house. A while ago, some contractors were working near such a transformer. An accident caused the transformer to short out, sending a surge down the line and into my friend's house. It fused the switchboard and power outlets, and basically destroyed everything that was plugged into a power outlet, regardless of whether it was switched on or off. I don't think that a surge protector would have made a hair breadth's difference in this case. Plasmic Physics (talk) 11:23, 9 October 2012 (UTC)[reply]
The one thing that people should avoid seems to be the old landline telephone. According to this, on average one American dies each year from a lighting strike on his telephone line. Non-lethal effects include ruptured ear drums and electric burns. Running the telephone wires on utility poles instead of under the ground may be a risk factor. Ssscienccce (talk) 14:02, 10 October 2012 (UTC)[reply]
While it is in the sense that the pole is more likely to be struck directly, underground lines are at just as much of a risk in the same way that underground plumbing can transmit lightning (it's also best to avoid taking showers/baths during thunderstorms). Ks0stm(T•C•G•E)03:34, 11 October 2012 (UTC)[reply]
I was thinking that once it went underground, the voltage would be lowered considerably, making it less likely to travel through the air again from phone to person. With plumbing people can be in direct contact with both drain and water pipe. Mains voltage would be enough to kill them. Ssscienccce (talk) 04:15, 13 October 2012 (UTC)[reply]
Mine made a ball lightning once. It was an almost perfectly clear, orange sphere ~3" in diameter. When I saw it, I opened the door (stupid move, i know) and it flew out at my face and bounced off, and disappeared.
(Speculation ahead) Or then I thought it bounced off my face. Today I would rather speculate that a stable ball lightning tends to avoid(in the sense of being repelled by) conductors like the oven and its door, and humans, and when I opened the door, it could get out of the oven until I was in the way, so it stopped some inches short of me and changed direction. I did not feel anything, so there was probably no contact at all.
After that, the ball moved around a bit and disappeared after 2 or 3 seconds, about 1 foot below the ceiling. I think it didn't touch anything, it just faded.
And I was unable to reproduce the ball lightning in over 100 attempts. It must have been the perfect mix of a dodgy microwave oven, too small a food portion for near-full power, and who knows what. - ¡Ouch! (hurt me / more pain) 07:22, 15 October 2012 (UTC)[reply]
It's fun to make microwave plasma. I have a setup which works every time, which usually produces a white-violet vortex of plasma accompanied by a sound that sounds like a vocalised razz.
The setup consisted of an inverted spherical glass vase covering a spark gap, a saucer with water on the side to protect the magnetron. The spark gap consisted of florist's sponge inserted into a bottle screw cap. Two lengths of graphite pencil leads were inserted at an accute angle, ~5 mm appart at the top, into the sponge base. An unused match was inserted between the leads, pointing up. I tried using bentonite clay as a base, but it melted into glass. Plasmic Physics (talk) 08:42, 16 October 2012 (UTC)[reply]
Relative speed and position
If I am here and I am then being on the Earth I'm traveling +- 1000mph. Traveling around the Sun I'm traveling +- (way fast) On through the Milky Way and so forth to the outer limits. Then where are we? Where are we going and how fast? Shalom, Tim Jagoe — Preceding unsigned comment added by 108.249.61.251 (talk) 02:52, 9 October 2012 (UTC)[reply]
"where are we?" Relative to where? Neither position or speed have any absolute value. They can only be expressed in relation to something else. AndyTheGrump (talk) 03:35, 9 October 2012 (UTC)[reply]
Andy's point is the entire point of the various "Theories of Relativity", especially Special relativity, but even it's predecessors Galilean invariance and Newton's third law or its sequel General relativity. All of these theories basically have the same principle: there is no privileged frame of reference. That is, there is no point in the universe which can be considered to be "standing still" against which we measure the motion of other objects, except in a purely arbitrary sense: we define "still" generally from where we, as an observer, is standing, but that choice is arbitrary, and the laws of motion are the same if another frame were to be chosen. Or to put it simply, if I say that I am standing still and you are moving, that is completely identical to claiming that you are standing still and I am moving. --Jayron3204:18, 9 October 2012 (UTC)[reply]
Since cats have traditionally been useful for keeping down rode.t numbers it seems likely that we would have encouraged wanton killing. But what'a with them leaving dead animals on the doorstep or similar place for us to find. Are they giving us the food, or simply frequently happen to drop it there by coincidence.
Is it possible that we have encouraged the trait of bringing us food much the way it would bring its own kittens food? Its the only way I can see that they would get anything out of it — Preceding unsigned comment added by 149.135.146.109 (talk) 03:17, 9 October 2012 (UTC)[reply]
If you read Cat#Hunting_and_feeding it has some good information on "presentation of dead animals to owners" as you describe. There's also some links, via the footnotes, to other sources on the behavior, but I think the salient point made in the Wikipedia article is "One poorly understood element of cat hunting behavior is the presentation of prey to human owners." (bold mine) In other words, science hasn't got a firm grasp on explaining the behavior in a conclusive way. I'm sure a dozen people after me will present some unreferenced folky explanation on what cats are doing when they do this, but perhaps someone will come along with some solid references that contradict the Wikipedia article to say that this is "poorly understood". --Jayron3203:27, 9 October 2012 (UTC)[reply]
Jackson Galaxy might know. For the rest of us, it's pretty obvious that the cat is bringing a present to its owner. Cats aren't pack animals like dogs are, but they do have a sense of a "pecking order". ←Baseball BugsWhat's up, Doc?carrots→ 03:48, 9 October 2012 (UTC)[reply]
And in steps Bugs with an unsourced 'explanation' ;-) Actually, I've heard another, entirely contradictory 'unverifiable explanation' - that cats, having never seen humans catch mice, assume that they are kittens in this respect, and need to be taught how to do it - hence their predilection for bringing home live specimens for us to practice on. The truth is though, that we don't know. If I remember correctly Wittgenstein said that 'if lions could speak, we couldn't understand them' or something to that effect. Felines are different from us, and trying to understand their behaviour in terms of 'why' rather than 'what' may be a futile endeavour... AndyTheGrump (talk) 03:58, 9 October 2012 (UTC)[reply]
I wonder if we selected for it, it if wild cats will do it inately. I wasn't aware that wild cats are very sociable. Even if they are more social creatures than I realised, presenting an alpha with food is quite an advanced social tool! The idea that cats see their owners as a mixture of mother and kitten seemed mire plausible but I was merely hypothesized with no evidence. — Preceding unsigned comment added by 149.135.146.89 (talk) 04:03, 9 October 2012 (UTC)[reply]
I'll go with Bugs here. Specifically, cats exhibit behavioral neoteny, meaning we have selected for cats which maintain kitten-like qualities into adulthood. This is even more true when we have them neutered. Their owners take the role of mother (regardless of gender), unlike with dogs, where the owner is the pack leader. As such, bringing home caught prey to their mother is a way to demonstrate their value and gain approval. I also suspect that people, in the past, have been more wiling to allow a successful hunter to live with them, as that shows the cat is "doing it's job" to keep down the rodent population (very important for those with grain stores). StuRat (talk) 04:11, 9 October 2012 (UTC)[reply]
I'd agree with neoteny being a factor in the domestication of most animals - I'm not entirely sure how true it is of cats though, in that their 'domestication' as pets seems to be relatively recent, and there may have been little selective pressure to change behaviour beyond a willingness to hang around where the humans are - because that is where the mice are to be found. AndyTheGrump (talk) 04:19, 9 October 2012 (UTC)[reply]
But "adult" cat behaviors, which we've now largely bred out of them, would involve them hissing and scratching and biting us, and would get them thrown out into the cold quite fast, if not outright killed. Domestic cats have been around for thousands of generations, which is enough for selection pressures to work their magic. StuRat (talk) 04:27, 9 October 2012 (UTC)[reply]
I haven't tried to work out the answer yet, but I should point out that the African wildcat is what will display evolutionarily sensible behavior; the actions of domestic cats, as pointed out above, may be different. Wildly speculating (which I shouldn't do because there's probably an answer to this one) I'm prone to compare this to the various sorts of gun dogs, pointers and setters and retrievers, which I've seen explained plausibly as caused by a defect in the natural hunting instinct at various points in the process, from the moment the prey is first sighted to the point where it is about to be devoured. Wnt (talk) 06:03, 9 October 2012 (UTC)[reply]
As a long time cat owner (40+ yrs), I suspect that the cats leave the dead animals not as a gift, or as food but the place we find the animal is where the cat got bored of playing with it or eating it and wandered off. 217.158.236.14 (talk) 09:22, 9 October 2012 (UTC)[reply]
Weirdly enough, I just received this in my email: a comic from The Oatmeal. Anyway, it sources a National Geographic and University of Georgia project, called Kitty Cams Project, which studies domestic cats when they're away from the prying eyes of their human owners. I can't vouch for its legitimacy, but there we go. – Kerαunoςcopia◁galaxies09:37, 9 October 2012 (UTC)[reply]
On a somewhat similar point, I would say you're somewhat lucky when all you find is half of a dead animal (or whatever), far worse when your cat brings in a bird, gets feathers and possibly blood everywhere while playing with it for many minutes while it (the bird) screeches only to get bored of it and leave the half dead bird somewhere and you have to decide whether to kill the half dead bird or let it die naturally. You can of course try to save the bird but unless you're either willing to play the vet bills everytime it happens or continually bother volunteer bird rescue groups there's a fair chance the bird will die anyway, particularly once the cat learns you'll take the bird off it. Worse still when your cat brings in a live mouse or rat, only to find 10 minutes later the cat desperately searching for the mouse or rat. Anyway to get back to the original question, I think this sort of thing highlights why we need to be careful with evolutionary explanations, logically playing with your food to the extent you may lose it is not advantageous particularly when your primary benefit to humans was in catching vermin. Even if this behavior has increased in recent times as catching vermin has become less important and neutering more common, is the fact this behavior still exists reflective of the fact it's not easy to breed out without either negatively affecting learning, other desirable behaviours, or simply suggestive as with most cases, it's likely fairly complicated? Nil Einne (talk) 12:48, 9 October 2012 (UTC)[reply]
What would be the evolutionary pressure which would breed this behavior out of cats ? How many people would neuter or kill their cat because it did that ? StuRat (talk) 21:49, 9 October 2012 (UTC)[reply]
If I had to take a wild guess (a flagrant Just-so story) I would speculate that a cat that efficiently catches and eats the mouse will get filled up and stop bothering them, but one which plays with it and forgets it will keep going after more. And such a cat, maybe, would get a reputation as a "good mouser" and be preferentially bred. (Leaving the remains where the owners could see probably wouldn't have hurt either) Wnt (talk) 22:56, 9 October 2012 (UTC)[reply]
Another possibility, equally unreferenced but in my opinion more plausible: Cats that "practice" hunting when game is plentiful are more likely to be able to feed themselves when it's not. So if they're not particularly hungry, they "play" with the mousie to hone their reflexes (and may not even eat it at the end).
This one is even somewhat testable — see if hungry cats are less likely to play with their food, and whether cats that engage in this sort of practice become more skilled. --Trovatore (talk) 08:33, 10 October 2012 (UTC)[reply]
This may indeed be more convincing than my scenario, especially when I remember that carnivores tend to be scavengers as well - in the wild, a rotten mouse stashed in a "safe" place might still be food in the future. Wnt (talk) 16:13, 10 October 2012 (UTC)[reply]
As Jackson Galaxy often explains, cats are hard-wired to hunt and kill. That basic fact explains a lot about their behavior. I saw a story recently where some outdoors cats were equipped with small cameras so that observers could see what they were up to. It turns out they were killing a lot more prey than people generally assumed. ←Baseball BugsWhat's up, Doc?carrots→ 02:30, 10 October 2012 (UTC)[reply]
I think it's quite likely in the past when cats were not really seen as pets as such, a cat which keeps losing vermin (particularly if it brings them from further away) rather then killing them would find itself out of favour of any humans it tries to live near them. Whether it would be killed or simply thrown out or have to leave because of the human reaction is largely a moot point; it's very unlikely neutering comes in to it much, remember we are talking about hundreds or thousands of years in the past and when cats weren't seen as pets much. Wnt does have a point that it's not clear whether what the cat was doing would have been appreciated as such. Although it's also worth considering from a results POV, while no one was doing scientific experiments, if humans found the vermin level has not decreased much or perhaps even increased they're far less likely to see a reason to keep cats around then if they found them significantly decreased. And if the neighbours cat (or an old cat) seems to have been far more effective this could also affect the chance of the cat being kept. Of course even lost vermin may die from the injuries, but they generally have a more effective immune system then birds. In fact, it's even possible there would be greater evolutionary pressure on this sort of behaviour for quite a while then stuff like biting. If a cat is helping with the vermin population even if it doesn't really let humans handle it this could easily be more successful then on which does not help with the vermin population but lets humans handle it. In any case, it does demonstrate the point you need to take care when considering evolutionary explainations. Nil Einne (talk) 03:23, 10 October 2012 (UTC)[reply]
Yeah, I don't think we'll get to any real answer unless we come up with more observations on the behavior of Felis silvestris lybica. Wnt (talk) 16:13, 10 October 2012 (UTC) -- hmm, while I didn't see anything naturalistic about it on NCBI, I did stumble across a commercial photo stock image of European Felis silvestris playing with prey. Unfortunately the author isn't credited that I see, so asking him would be a paper chase ... still, there must be people contactable somewhere who have observed these cats in the wild or in zoo-like conditions who can tell us if they play with prey like domestic cats. (though we should be careful of assumptions based on little evidence but presumed resemblance) Wnt (talk) 16:22, 10 October 2012 (UTC)[reply]
I am not quite sure what the mystery is here. Domestic cats are usually not starving. So if they do catch prey, why wouldn't they bring it back to the den just like wild cats do, either to eat later or share with the family? I am allergic to cats. So perhaps I am missing out on their being some other behavior that needs explaining, like the cat pawing you with a bird in his mouth, or doing a little end-zone dance to get your attention? μηδείς (talk) 17:14, 10 October 2012 (UTC)[reply]
They do a strange twitching thing when stalking prey. I attribute this to the effects of adrenaline flooding their system as they try to keep still. StuRat (talk) 15:47, 11 October 2012 (UTC)[reply]
Our eyes detect light and we can determine size and scale. If there were beings whose heads were as big as the sun would their eyes be able to see as detailed as ours? The same amount of photons would be shining on them?GeeBIGS (talk) 05:21, 9 October 2012 (UTC)[reply]
They probably could not see things as small as we can. We can't make out items as finely as a spider can. I think the issue is that larger lenses cause larger distortions, making it more difficult to focus on smaller objects. Now, what I'm unsure of is if our eyes could be much better for viewing small objects, if there was evolutionary pressure for them to be so. I'm quite nearsighted myself, and, without contact lenses, I can make out very tiny objects, like the individual dots on a printed picture, but only if my eye is within a few inches (that's too close for binocular vision to work). So, perhaps a nearsighted Sun-sized creature could see more detail at very close range, but not at the distances of planets. StuRat (talk) 06:55, 9 October 2012 (UTC)[reply]
I'll second Stu's experience regarding distortion. I as well can make out small details without my contacts; they distort my close vision for the sake of giving me decent distance vision. Optical aberration has some details which may help as well. --Jayron3218:18, 9 October 2012 (UTC)[reply]
I don't really understand the question. Is it asking whether a head exactly like ours except scaled up to the size of the sun would be able to see things a fraction of an inch in size? Or whether it would be able to see things that are scaled up to an equal degree? Looie496 (talk) 18:50, 9 October 2012 (UTC)[reply]
That is, "whether a head exactly like ours except scaled up to the size of the Sun would be able to see things a fraction of an inch in size". To that I say no, although they could see smaller things close up (but not that small), than if focused on distant planets. StuRat (talk) 00:44, 10 October 2012 (UTC)[reply]
If you simply scale up everything in the eye, there's no way it could detect tiny things, because scaling up the photoreceptor cells in the retina would mean they would have vastly larger receptive fields. Looie496 (talk) 02:05, 10 October 2012 (UTC)[reply]
I don't know, but it would be simpler to mount a camera on the spider. We have cameras that fit into the human bloodstream, so a large spider would easily be able to carry one. Nyttend (talk) 20:08, 10 October 2012 (UTC)[reply]
I suspect that a spider is extremely nearsighted, as they need to see their prey when they approach it, not things on the other side of the room. So, it would be useless as a spy camera. StuRat (talk) 15:43, 11 October 2012 (UTC)[reply]
Can anyone do this?
Does anyone know how to put his little toe on the second toe?
I couldn't, but I have small, stubby toes. My wife could do what's in that video easily. She's got toes she could play piano with. People have different feet. --Jayron3216:52, 9 October 2012 (UTC)[reply]
My toes are quite long, but they don't move like that, at least not on their own. Presumably this is because the muscles needed to do such movements aren't well developed in my little toes. StuRat (talk) 21:40, 9 October 2012 (UTC)[reply]
Some muscular control is also innate and not that trainable. Some people can curl their tongue and others cannot; some people can wiggle their ears and others cannot. I don't know that there's an explanation or mechanism as to why not, but tongue rolling or tongue curling (two different tongue movements) is one of those "you can do it or you can't" things, and I'm not sure it is trainable. Our article on tongue rollings states that it is an "intrinsic" property of the musculature of the tongue, but also says that it has no demonstrated genetic component. I'm not sure how to resolve that in my mind (if something is inborn, but not genetic, what does that mean?!?) but it isn't a trainable skill. --Jayron3221:58, 9 October 2012 (UTC)[reply]
Oh, that's brilliant. I knew that Bene Gesserits were the daughters of the Jesuits (under whom Herbert studied) but didn't know this too had a real-world antecedent. The novel is far more ecumenical (Orange Catholic, Zen-Sunni) than just Muslim. There are even real live Jews in Heretics and/or Chapterhouse. μηδείς (talk) 02:20, 11 October 2012 (UTC)[reply]
if you mean the first image, with the animation, I believe I've seen it before in videos of a Japanese guy making miniature, fake food. It came in a kit that you had to mix all the bits together, then form the food. It's called "Konapun". — Preceding unsigned comment added by 217.158.236.14 (talk) 12:59, 9 October 2012 (UTC)[reply]
Sorry. I thought it would be a direct link. I'm talking about the 14th image. I get a grid of images four across. In which case I'm talking about the second column, fourth image down. The two hemispheres. Dismas|(talk)14:08, 9 October 2012 (UTC)[reply]
At my place of work, our (very old) microwave oven is acting strange recently. Sometimes, the turntable will begin turning and the microwave sound like it is running when the door is opened (after having stopped/not been in use). Some of my coworkers are wondering: Could a microwave oven that's on while the door is open be dangerous, perhaps leaking radiation? If so, is it an amount of radiation to be worried about? Thanks! -- 143.85.199.242 (talk) 19:34, 9 October 2012 (UTC)[reply]
And unplug it until you can have it serviced or disposed of. On the plus side, if it's just an issue of the door switch sticking closed, that ought to be easy and cheap to fix. Just cleaning the switch might do it. StuRat (talk) 20:27, 9 October 2012 (UTC)[reply]
Ugn, not even worth considering, bin it and get a replacement, it's a potential health hazard. Tell them either buy a new unit for $150 or risk a law suit.Vespine (talk) 23:12, 9 October 2012 (UTC)[reply]
$150 would be a premium version. The cheap one you linked to runs $30-$40 in the US. I actually prefer the cheap ones, though, as it's much quicker to turn two dials than to navigate through menus to try to get the darned thing to turn on. One thing I'd prefer, though, is if they don't have those levers you have to hit to get them to open. Those can stop working if they get dirty. I prefer a big handle you can yank open. StuRat (talk) 01:14, 10 October 2012 (UTC)[reply]
Most decent microwaves with digital controls have a 1 minute or similar button meaning there's no need to navigate any menus. In fact most don't have menus for normal usage, even if you don't want to use the 1 minute button, simply push the buttons for the time and push start. One big advantage with fancier microwaves is you can get one with an inverter meaning you have less problems when using it at non full power. Nil Einne (talk) 03:44, 10 October 2012 (UTC)[reply]
You've hit on a pet peeve of mine. To get the quality item, I often have to accept unwanted electronics. For example, I'm fine with manual adjustments on my car seat, except that I'm often limited to just forward/back and maybe tilt. If I want additional degrees of freedom, like an up/down control, then I not only must accept those additional features being controlled by motors, but the basic features, as well. StuRat (talk) 06:56, 10 October 2012 (UTC)[reply]
I have to admit i had NO idea about the prices of microwave ovens, I chose $150 after doing a shopping search in australian google! After that, $150 seemed conservative! There are $200, $300 and even $400 models!! $30-$40?!? Forget foxconn! You gotta wonder about the conditions of the places where that kind of stuff is made.. Vespine (talk) 00:13, 15 October 2012 (UTC)[reply]
Can human nature evolve, and if it does evolve, can humans understand earlier humans thoughts millions of years from now?
Can human nature evolve, and if it can and does evolve, can humans understand earlier humans thoughts and motives and desires millions of years from now? 140.254.226.212 (talk) 19:38, 9 October 2012 (UTC)[reply]
Please see the top of the page where it states "The reference desk does not answer requests for opinions or predictions about future events. Do not start a debate; please seek an internet forum instead." This isn't the correct venue. --Jayron3219:41, 9 October 2012 (UTC)[reply]
I'm not sure what Jayron's problem with this Q is, looks perfectly valid to me:
1) Can human nature evolve ? Yes, personalities, willingness to cooperate with others, tendency towards violence, etc., are all aspects of human nature with genetic components. As such, they can evolve just like any other attribute, provided there is sufficient evolutionary selection pressure for them to do so. This means that the ability of people to survive and reproduce must be affected by these attributes.
2) As far as future human's understanding us, I don't see a problem there, as long as we leave behind records of our motivations. It's a bit harder when archeologists look at ancient humans, who lacked writing. You can get some clues, though, such as whether they buried the dead with important items or just tossed them into a hole. StuRat (talk) 20:26, 9 October 2012 (UTC)[reply]
Yes, all we need to do is preserve Wikipedia, including all of the historic versions of the pages. There is then a continuous link from the present to the far future, making it easy to decipher ancient texts. Count Iblis (talk) 20:43, 9 October 2012 (UTC)[reply]
The second question is indeed unanswerable. To illustrate, it is possible that future humans will be exactly like present humans, by accident or design, in which case they can understand. But it is also possible that future humans will live in a dictatorship so appalling that the mere conception of being "free" causes one of them to immediately fall over dead by genetic design, in which case they cannot understand. Wnt (talk) 23:20, 9 October 2012 (UTC)[reply]
To give a less ridiculous scenario, humans and chimps are separated by "millions of years". Can you understand a chimp's thoughts and desires, and do you think a chimp could understand ours? The Aztecs are separated from us by 600 years; they considered it an honor for their living, beating hearts to be ripped out of their chests and sacrificed to the gods. Do you understand them? The Taliban are living in our own time, and they think shooting a 14-year-old girl in the head is OK. Do you understand them? (I do understand the Taliban's motivations, but many people don't; they resort to idiotic cop-outs like "they're just evil", "they're just crazy", or "the devil made them do it", which is essentially equivalent to saying "I can't understand X; therefore, nobody alive today can understand X, and nobody who will ever be born will understand X") --140.180.242.9 (talk) 22:30, 10 October 2012 (UTC)[reply]
I understand the Taliban's motivation as far as wanting everyone who disagrees with them to be afraid to speak up. However, they don't seem to have considered the negative PR implications of murdering children. Not the way to broaden their base of support. StuRat (talk) 15:39, 11 October 2012 (UTC)[reply]
I believe humans and chimpanzees are not in fact "separated by millions of years"; rather, they co-exist and are each separated from a common ancestor. 82.31.133.165 (talk) 21:43, 15 October 2012 (UTC)[reply]
Genetic bottleneck from the KT and Permian mass extinctions
Can one calculate that there were mass extinctions about 65 and 250 million years ago using only the data from genomes of modern animals? Count Iblis (talk) 20:36, 9 October 2012 (UTC)[reply]
I think in principle it should be possible: the signature would show up as large numbers of species-pairs having their last common ancestor around 65 or 250 million years ago. To make it work, though, techniques for genetic dating would have to be improved, and the genomes of a lot more species would need to be sequenced. Note that this not the sort of bottleneck that is normally discussed -- the normal kind is where the number of individuals in a species becomes very low for some period of time. The technique for detecting that is quite different from the one I just gave. Looie496 (talk) 21:50, 9 October 2012 (UTC)[reply]
The method you are referring to is the molecular clock. The problem you'd run into, besides its general inaccuracy, is that few lineages date to the boundary itself. The Galloanserae date to well before the KT boundary, and songbirds to maybe 15 million years after. This paper shows most placental orders predating KT.[8] And there is no common protein or gene that evolved at, was selected by, or which links all the survivors of those events. I'd be surprised, if you knew what you were looking for, and had huge resources, if some statistical correlations couldn't be teased out of the data. But the chances of stumbling across such an event unless you already knew what you were looking for based on other evidence? μηδείς (talk) 02:24, 10 October 2012 (UTC)[reply]
DermaWand®
I've watched an informercial selling a dermatological device which claims to do all sorts of wonderful things for your skin, including reversing signs of ageing. Not that I'm in the least interested in using this device, but it does raise some questions. In the informercial, it was noted that during opperation, the device produces a scent associated with an electical storm, which can only mean ozone. Ozone is highly oxidising, which has the opposite effect of rejuvenation. What is really going on, is the effect of skin exposure to ozone negligible, is it cummulative, is it longterm. This reminds me of Venetian ceruse, on account it it causing a positive feedback loop: using it damages your skin, the more your skin was damaged, the more you used it to cover up the damaged skin. Plasmic Physics (talk) 00:28, 10 October 2012 (UTC)[reply]
I wouldn't expect ozone to have much effect on your skin, since it's covered with a layer of dead skin. An exception would be for someone who just had a seriously chemical peel. Your lungs, on the other hand, could be damaged by a high concentration of ozone. StuRat (talk) 00:41, 10 October 2012 (UTC)[reply]
Hmmm, let's begin by trying to find out what it is. "DermaWand is a condensed version of the exact same technology found in large commercial high frequency machines used by skin care specialists all over the world for 40 years ... stimulates and rejuvenates by sending out a gentle stream of low level micro-current impulses up to 168,000 cycles per second, imitating hundreds of tiny fingers that massage your skin ... helps improve circulation bringing oxygen and vital nutrients to your skin's surface. The gentle micro current also has a thermal effect on the skin s surface, helping the skin look more toned and tight, smoothing out the appearance of fine lines and wrinkles. Plus DermaWand oxygenates by giving off enriched oxygen that cleanses and purifies, helping breathe new life into your skin's surface. "[9]
Hunting for "high-frequency" "skin" "dermatologist" on Google yielded [www.scirp.org/Journal/PaperInformation.aspx?paperID=20115[predatory publisher]] "investigated the skin rejuvenation effect of dual-frequency ultrasound, with frequencies of 3 and 10 MHz, which has the ability to modulate both MMPs and HSPs. It was shown that such waves can significantly improve different visual appearances of ageing skin. This safe, non-invasive method yields results that are not as marked as those shown by injecting of fillers, but can be successfully used by subjects with a broad spectrum of visual skin ageing problems, which have to be treated simultaneously." This in the open access but never heard of before by me Journal of Cosmetics, Dermatological Sciences and Applications, so I'll present this more as a statement of their POV than as fact until I know more. The most applicable source from their introduction is something from Med Hypotheses [10] which... is less than persuasive. But the way the data is presented, measuring skin a week after the last of 8-12 biweekly treatments, and the data they present, suggesting at least a short-term improvement, doesn't look unreasonable. Now the question is whether we can find enough evidence to inform us about this treatment's effect in any longer term... Wnt (talk) 00:43, 10 October 2012 (UTC)[reply]
To my surprise, there's more about this at NCBI: [11], PMID21332912, PMID21284234, PMID21283035, PMID20115948, PMID19204844. Some of the references later on the list (older) sound more serious. I'm mixing two different high-frequency treatments - radio frequency and ultrasound - because I'm still not sure which the "wand" is, if either. The gist appears to be to heat the skin, damage collagen fibers, have larger new filaments reform to produce a tighter/less wrinkled look. There might be something to this; there's not much of a theoretical reason why you can't rejuvenate wrinkled skin because there's probably only recent cultural selection against it. Wnt (talk) 00:54, 10 October 2012 (UTC)[reply]
There's an "Ozone Cleansing Beauty Device (personal high frequency)" marketed with all kinds of claims "a versatile handheld esthetic tool that uses ozone / o3 which has three oxygen atoms that is power to sterilize, detoxify, deodorize and whiten your skin.Ozone Cleansing Beauty Device gives you a refreshed feeling and has a powerful function for reducing inflammation, reducing pain, balancing the pH of the skin. Moist importantly, Ozone Cleansing Beauty Device's high frequency current has an antiseptic effect on the skin that will detoxify bacteria caused by acne breakouts". Maybe the same circuit inside but aimed at a different audience? Ssscienccce (talk) 14:58, 10 October 2012 (UTC)[reply]
Depends what you mean by shelf life. If you leave one on the shelf for 3 years it'll be flat as tack, but roughly 80% of them will survive and will be usable after recharging. Greglocock (talk) 01:06, 10 October 2012 (UTC)[reply]
The shelf life is strongly dependent on temperature. It's hard to get good data, but there are two mechanisms that lead to reduced performance while on the shelf: gradual deterioration and self discharge. When any lead acid battery is substantially discharged, it's capacity sharply drops from then on. The general rule of thumb is that both gradual deterioration and self discharge double in rate for each 10 degrees C increase in temperature. The impact of self discharge can be eliminated by recharging - once each 3 months is the recommedation. If this is not done, expect the battery to be ruined within a year at ordinary sorts of mediteranian climate temperatures. However, there is another life-affecting mechanism - batteries will only last a certain number of charge-discharge cycles.
How long the battery will last does indeed depend on just what you mean by shelf life. My comments above are applicable to defining end of service life as the capacity reduced to 80% of rated value.
The following discussion has been closed. Please do not modify it.
(All this discussion really belongs on a talk page, not here, but you have no screen name and a dynamic I/P, so you have no talk page to post to. You should have posted any criticism of me on my talk page, not here, so this discussion could take place off the Ref Desk. I've moved it there now: User_talk:StuRat#Detroit_weather.) StuRat (talk) 19:09, 10 October 2012 (UTC)[reply]
The shelf-life will vary depending on the battery and the conditions it is exposed to. If your bettery is well-marked (some cheap ones aren't) you should be able to look up the manufacturer, and they may have a data sheet available. It will outline things like discharge rate over time, effects of different charging voltages and cycles, and expected lifetime under different conditions. 209.131.76.183 (talk) 13:52, 10 October 2012 (UTC)[reply]
According to a recent NYT article, doctors are now considering amphetamines as good for all kids in low-income, poorly funded school districts, not just some special group who show the "reverse effect" or whatever. [12] But although I still remember it as the new drug that some kids at college used to stay up on finals week, methamphetamine is more demonized than ever, an addictive scourge that leaves people batshit crazy, worn out and used up, missing teeth. Is there any way to make sense out of this, to say whether amphetamines are good or bad, or explain when they're good and when they're bad? Is it age of the user, impurities in the preparation, or is the explanation actual, literal transsubstantiation at the tip of a Licensed Doctor's pen? Wnt (talk) 01:10, 10 October 2012 (UTC)[reply]
Yes, there is a way to make sense of it. The brains of children are neurochemically different in some ways from the brains of adults -- in particular the dopamine system, which is targeted by drugs like amphetamine and Adderall, seems to be more active in children. Basically if you see an adult who is addicted to amphetamine or another dopamine agonist, that adult will act in a number of ways like a five-year-old: impulsive, hyperactive, etc. So it is plausible that drugs that act on the dopamine system will have different effects on children than on adults. I'm not asserting that it is true, just that it is plausible. Looie496 (talk) 01:59, 10 October 2012 (UTC)[reply]
(edit conflic with above) I don't think we need to theorize about differences between child and adult brains. There are plenty of adults who are prescribed amphetamines too. The issue's very similar to the recreational abuse of other prescription drugs (vicodin, etc.). A trained medical professional can decide when it is likely that the benefits of a given drug will outweigh the potential costs, and can proscribe the dosing. When taken recreationally, people often take more than a doctor would proscribe, on a less regular schedule, and don't monitor for potential side effects. Though demonized as a recreational drug, Methamphetamine can be prescribed. As I understand it there are some issues with dependence, but the side effects aren't particularly bad when taken in a controlled manner. As you suggest, it probably helps that it's being made by drug companies instead of gangsters (residual hydroiodic acid isn't particularly good for you). The infamous meth mouth, while probably partly due to the drug itself (similar effects are seen to a much lesser extent in people prescribed amphetamines), is probably more a result of the poor diet and dental hygiene of most meth addicts. Buddy431 (talk) 02:10, 10 October 2012 (UTC)[reply]
And that's not to say that there aren't side effects that can occur when amphetamines are taken under a doctor's supervision: cardiac problems, possible psychosis, etc. There are some countries where amphetamines are illegal under all circumstances. Canada briefly banned Adderall in 2005 due to possible risk of sudden death from cardiac events. But again, when taken at therapeutic doses, especially under the eye of a doctor, these side effects can be monitored, and at least in theory, the benefits of the drug will outweigh the risks. Canada later allowed it to be prescribed again, figuring that the benefits to many people with ADHD outweighed the slight cardiac risks. Buddy431 (talk) 02:32, 10 October 2012 (UTC)[reply]
Most amphetamines - including methamphetamine in many of its common forms - are Schedule II Controlled Substances in the United States. This means that, according to 21 USC § 812[13], "The drug or other substance has a currently accepted medical use in treatment in the United States or a currently accepted medical use with severe restrictions." This specific legislation has been in effect for several decades, and the classification of methamphetamine has not changed in a very long time (1970, and 1971 in other forms). So, there's nothing to be confused about: methamphetamine is widely recognized as a very seriously potentially harmful controlled substance that also has certain useful medical properties. There's no conundrum. In fact, if you read any of the literature promoted by the Department of Justice's Drug Enforcement Agency, it's actually fairly progressive in its stance: these drugs are controlled because they have potential to do harm. The Methamphetamine fact-sheet states clearly: "it has a high potential for abuse and limited medical use. It is available only through a prescription that cannot be refilled. Today there is only one legal meth product, Desoxyn®. It is currently marketed in 5-milligram tablets and has very limited use in the treatment of obesity and attention deficit hyperactivity disorder (ADHD)." Note the critical distinction between illegal and controlled. And even these two descriptions have absolutely nothing to do with whether the substance is good or bad. If you need help differentiating good from bad, chances are very high that you will never get an answer from the DEA, or from a doctor, or from the reference desk. Perhaps you should consult our article on the philosophical analysis of good and evil. Nimur (talk) 03:37, 10 October 2012 (UTC)[reply]
This is a well-written and respectable answer ... except that it conflicts with the initial article saying that it is now being used on kids without ADHD. Wnt (talk) 16:26, 10 October 2012 (UTC)[reply]
The article Attention Disorder or Not, Pills to Help in School, mentions Adderall. Adderall is not methamphetamine. According to the United States Food and Drug Administration's Adderall (R) CII fact-sheet, "ADDERALL® is indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) and Narcolepsy." In other words, it may apply to medical treatment for "kids without ADHD." In fact, only a qualified medical professional would know whether it is applicable; and only a qualified legal professional would know whether it is legal; but you can peruse the many pages of public information made available by the FDA and by the drug vendor to inform your own opinion about it. Now, whether I would personally trust a doctor who prescribes this medication is a moot point; (I wouldn't); but again, despite a bit of journalistic sensationalism, there's no clear indication that the medication is being used or marketed in a way contrary to applicable regulations or medical need. We have articles on Risperdal and Clonidine, the other medications mentioned in the New York Times article; and the FDA provides fact-sheets for each, as well. Nimur (talk) 17:29, 10 October 2012 (UTC)[reply]
I'm not asking a sophisticated medical or legal question here. What I'm thinking is that, except for very heavy users, recreational users of methamphetamine or amphetamine (I haven't seen any indication they work differently, though there's another possibility) are not consuming more overall than those prescribed the drug on a daily basis. The kids often are free not to take the drug as prescribed, but to grind it up and snort it, possibly in binges for tests or for recreation. [14] So I don't see any difference, except in a religious sense, between the use of the drug as purchased illegally on the street and as used by at least a significant fraction of the kids to which it is medically prescribed. So to put it bluntly I would expect that, if half the stories about meth heads are true, that we would have kids on the prescription setting up guns and tripwires in their school lockers to guard against CIA agents pilfering their stash. There's something about all this that just doesn't fit, unless there's some important but unaccounted factor like an impurity in the street drug, or somebody is seriously lying about some aspect of how the drug is affecting some group of people, or if it's only dangerous when used at more than a critical (large) dosage, etc. Wnt (talk) 19:22, 10 October 2012 (UTC)[reply]
Why do you believe that someone recreationally taking meth or amphetamine is not taking more than prescribed? The term "Meth Head" indicates someone who is addicted, has built up a tolerance, who might be taking 60+ mg a pop (typical prescribed does is in the range of 20 mg/day, probably taken in two doses, or before meals if for weight control). A recreational user is also more likely to inject it, smoke it, or snort it, whereas someone prescribed an amphetamine will be taking it orally (and thus getting more of it in the system quickly). If they inject it, they are often doing so with a used needle, giving themselves HIV, Hep. C, etc. Street drugs are notorious for being cut with fillers, which are often not harmless. The production of street meth is often not done very carefully, and might have leftover byproducts, which certainly aren't harmless (Phosphorus, Hydroiodic acid, etc.) Buddy431 (talk) 20:09, 10 October 2012 (UTC)[reply]
Both of you are essentially stating your estimation of a descriptive point, namely how much meth is typically consumed by a recreational user, as fact. How about some real facts? I would be curious to know whether there is such a thing as a controlled recreational user, someone who knows his limit and stops, and if so how common such a thing is. Are there any reliable data on that? (I concede that there might very well not be any good data on it; such people, if they exist, presumably stay under the radar of law enforcement and of addiction treatment facilities.) --Trovatore (talk) 20:13, 10 October 2012 (UTC)[reply]
I estimated my typical "street dose" from this probably unreliable source. If we look at the slightly more reliable PBS FAQ, it suggests a "hit" of about a quarter gram, which, if it's 50-70% pure, is quite a bit higher than my estimation. The point remains that it's significantly higher than what a doctor would prescribe. Buddy431 (talk) 20:37, 10 October 2012 (UTC)[reply]
Uncle Fester (not the most reliable source) recommends a maximum dose of 50mg a day, maximum 5 days a week in one of his books; but if a topic about daily dosage on a drug forum can be trusted, most meth heads would be taking 200 to 500 mg. If used to enhance productivity the Erdős way, 10 to 30mg would be sufficient.
Given the mechanism of action, tolerance will build up rapidly, at least for the stimulant effects. Hallucinations and psychosis are likely to develop, in experiments they were able to induce hallucinations in all test subjects by increasing the dosage. The difference between the effects of small and large doses could be related to the type of vesicles involved; at low doses, the large vesicles release dopamine, at large doses also the small vesicles start releasing.
Phosphorus and hydroiodic acid are unlikely adulterants, especially HI would never survive the acid/base extraction. Iodine salts may be present, and chloro-ephedrine has been found in street meth. Red phosphorus isn't especially toxic, otherwise match boxes and matchbooks would come with health warnings, the striking surface is 50% phosphorus.
Hmmmm, this source [15] says that "an average dose of meth is about a quarter of a gram. Because of ice’s intensity, smaller doses provide bigger highs; a gram of ice can provide 10 to 25 hits (doses) of meth. Heavy meth users take three or more grams of meth at a time." Apparently purity is a really major factor in trying to understand what the dose is... Wnt (talk) 03:35, 12 October 2012 (UTC)[reply]
October 10
Awareness of the link between sex and reproduction
At what point in our evolution did humans become aware of the link between having sex and reproduction? Given the time interval between the two, it doesn't seem that the former would necessarily imply the latter. Do chimps know? Chris (talk) 10:38, 10 October 2012 (UTC)[reply]
The ability to "be aware" or "be self aware" is not an easy thing to define, and it depends on how you work out your terms. Sentience and Sapience and Self-awareness and Theory of mind are all at least tangentally related to answering the question, and some directly required. Even for chimps, there's a major problem with answering the question, which is you'd need to be able to ask them to get direct evidence of that level of knowledge. The only way to infer without directly asking is to assert that a certain level of self-awareness and sapience is necessary to make that connection, and then we get into the thorny problem of defining those terms. --Jayron3212:26, 10 October 2012 (UTC)[reply]
Assuming that chimps are sentient but also have very limited communication skills, the only way a chimp could know about this link is if she made the connection herself. This is less likely to happen for a chimp than for a person. (1) I wonder if there are case studies of pregnant young women who didn't know the connection. If so, that would suggest that maybe human individuals in general only know the connection because it is culturally learned (and originally culturally discovered); in that case, chimps without high-level language would not be able to have it as part of their culture. (2) I wonder what/when is the first mention of the link in recorded writing. If that first mention came long after the advent of writing about the human condition, that might suggest that humans didn't know it at first, until it was discovered and disseminated into the culture. That strikes me as a long shot, though -- I would guess that even if the knowledge is not innate in each human, still society would have discovered it before writing was invented. Duoduoduo (talk) 15:10, 10 October 2012 (UTC)[reply]
Regarding the second question, even the oldest recorded stories (e.g. Egyptian mythology, see Osiris myth) make that link, and I don't doubt it was known even in prehistory. - Lindert (talk) 16:13, 10 October 2012 (UTC)[reply]
I read an article, which I'm struggling to find, which suggested that the connection likely came after the domestication of animals. It's a much clearer connection in say, a dog, which only comes into heat in certain times of year, rather than a human where we're fucking each other pretty constantly. Here's an interesting reply, with at least some research. It appears that aborigine Australians (who do not have domesticated animals until European contact) may have been unaware of the connection between sex and pregnancy. It's hard to sort through how much they were "really" ignorant, but anyways, it suggests that it's not as obvious as some of us might think. There's a couple other interesting resources linked on that page. Anyways, we'll probably never know for sure when the connection was made, but there's been some speculation among scientists (and others). Buddy431 (talk) 19:52, 10 October 2012 (UTC)[reply]
Well, the problem here is that the knowledge was obviously gained prehistorically. Things such as the triple goddess cult, with king stag celebrations and so forth imply knowledge of the link between sex and reproduction. One of the funniest criticisms I have ever heard of Christianity was a fellow student insisting to me that first-century Jews didn't know the link between sex and pregnancy, so the stories of the immaculate conception and Jesus's birth to the Virgin Mary had to be late middle-age forgeries! As if the people of ancient and classical times were cavemen. μηδείς (talk) 20:03, 10 October 2012 (UTC)[reply]
It was certainly prehistoric for some people, but evidently not for everyone (Australian aborigines, etc.) And just to be pedantic, the immaculate conception is a Catholic Dogma, and probably didn't really develop until the 7th century or so, and wasn't really officially sanctioned until the 15th century. Buddy431 (talk) 21:22, 10 October 2012 (UTC)[reply]
And then Europeans came (so it was no longer prehistoric), and documented this belief into the early 20th century. The connection, at least if the sources I cite are to believed, is not due to the development of writing but of domestic animals. Buddy431 (talk) 23:01, 10 October 2012 (UTC)[reply]
And not to be pedantic, but immaculate conception and the virgin birth of Jesus aren't the same thing (as is mentioned in the first few lines of the article you linked) Or does original sin have something to do with this?[The Ip directly above isn't me]Phoenixia1177 (talk) 22:45, 10 October 2012 (UTC)[reply]
That's not even remotely pedantic. The VB is the dogma that Mary gave birth to Jesus but remained a virgin. The IC is the dogma that Mary herself was born without original sin (which is supposed to be be why she was a suitable human mother for Jesus in the first place). The two events occurred at least 15 years apart. But I've come across astounding confusion about these dogmas, even in the minds of polymaths like Barry Jones (whose birthday it happens to be today, Thursday 11th here. Happy Birthday, Mr Jones). On page 495 of his Dictionary of World Biography (2nd ed. 1996), he states, in reference to Mary: The doctrine of her Perpetual Virginity (i.e. that she had no natural children) was adopted by the Council of Chalcedon in 451. Her Immaculate Conception (i.e. that she was the subject of a virgin birth) was proclaimed in 1854 by Pope Pius IX .... Both of his i.e.'s, which I've highlighted, are completely wrong. He may have corrected these gross errors in later editions. -- Jack of Oz[Talk]23:18, 10 October 2012 (UTC)[reply]
The person who presented the argument and I were both raised Catholic, so yes, we knew the doctrines were separate, and that's why I mentioned them both. His point in all seriousness was that people didn't know that conception resulted from sex until the renaissance or so, so that the doctrines couldn't possibly date back to early Christianity. The consensus in the class, including the history teacher, was that he was right that it was not known at the time of Jesus that sex was necessary for conception. That's simply absurd, whether or not it is true (which i believe it is) that Mary's immaculate conception was a later doctrine. Virgin birth myths predate Christianity. They obviously require the knowledge that sex is necessary for conception, since there would otherwise be nothing remarkable about a virgin birth, would there? Still makes me laugh to remember this. It is very striking if you study classical history how modern the ancients were in their science, philosophy, and even political corruption. Yet it is incredible how many people do think the ancients were basically cavemen in togas. μηδείς (talk) 02:08, 11 October 2012 (UTC)[reply]
Goodness gracious: it's patently ridiculous to believe that people 2000 years ago living in the Levant didn't know that sex made babies. I mean, as long as people have been breeding animals it is plain that people have known that sex makes babies. Anywhere with settled agriculture or animal herding should know that sex makes babies, and any claims that they didn't is so patently stupid as to deny the need to refute it further than that. --Jayron3202:18, 11 October 2012 (UTC)[reply]
Why would the average person know whether the Levant domesticated animals 2000 years ago? Large parts of the world didn't, like much of Africa and all of the Americas. The average person might know some ancient history, so they might know about Greece, Rome, Persia, Mesopotamia, China, the Indus valley, etc. But Judah/Israel was an insignificant backwater for almost all of history, and it's not inconceivable to take an entire world history class without hearing anything about it. --140.180.242.9 (talk) 02:57, 11 October 2012 (UTC)[reply]
If the average legally competent Westerner doesn't know that they had domesticated animals in the Mid East at the time of Caesar and Christ it's time we shut down wikipedia as hopeless. All indications are that the Amerinds who colonized the New World and brought the dog with them would have been aware of the connection back in 13,000 BC, as would all the Neolithic peoples of the Old World, at least those that were pastoral nomads and kept dogs, and presumably the New Guinea highlanders who farmed at least 7,000 years ago if not much earlier. μηδείς (talk) 03:13, 11 October 2012 (UTC)[reply]
If such people are basing their understanding of the situation on the Bible, discussions of Pastoralism are rife throughout the bible. Heck, Christian symbolism (the lamb, the shephard, the use of the word "Pastor") is filled with references to sheep herding. Sorry, it's just not feasible that someone can have read any meaningful part of the Bible and not have noticed that discussions of domesticated animals are all over it. Which is not to say that you aren't correct about stupidity in certain people, but that those people exist doesn't mean we need to accept that level of ignorance as normative. --Jayron3203:42, 11 October 2012 (UTC)[reply]
And just to prove that anyone with familiarity with the Bible should have also known that people living at the time the Bible describes understood the sex-baby connection, see Genesis 16:1-4 (from the New King James Version): "See now, the Lord has restrained me from bearing children. Please, go in to my maid; perhaps I shall obtain children by her." in v.2 and "So he went in to Hagar, and she conceived." in v. 4 Other translations use other euphemisms for sex here (the NIV uses "sleep with", as does the paraphrase "The Message"), but the Douay Rheims and all King James derivatives use "go in to her" as in enter her. As in, they're talking about the nookie here. So it is patently unacceptable that someone involved in religious education in any form of Christianity or Judaism could have thought that people living at the Birth of Jesus didn't know that sex made babies. The Abraham story is one of the oldest in the Bible, both in terms of its setting and authorship: if it's that plain in there, I just don't know what else I would say to someone who claimed otherwise. --Jayron3204:56, 11 October 2012 (UTC)[reply]
There's also something in there about Adam "knowing" Eve and conceiving children. The ancients didn't know about the microscopic specifics, of course, but they understood from observation that it took both a male and female, and also that the probability of conception was related to the menstrual cycle. To the minds of the ancients, the male had to "plant a seed" in the female to make a baby sprout. Hence the terms "sperm" and "semen", Greek and Latin respectively, which both mean "seed". ←Baseball BugsWhat's up, Doc?carrots→ 11:54, 11 October 2012 (UTC)[reply]
Actually, the text in Genesis 4 is may be more explicit than "knowing", that's among the English language euphemisms used in some translations, but you can tell by comparing various translations that many consider the phrase to unambiguously refer to sex. Douay Rheims American: "And Adam knew Eve his wife: who conceived and brought forth Cain", Complete Jewish Bible: "The man had sexual relations with Havah his wife; she conceived", English Standard Version (a King James derivative): "Now Adam knew Eve his wife, and she conceived and bore Cain", New International Version: "Adam made love to his wife Eve, and she became pregnant and gave birth to Cain", Orthodox Jewish Bible, "And HaAdam knew Chavah (Eve) his isha; and she conceived, and bore Kayin (Cain),". I even pulled up some non-English translations, this Spanish version says "El *hombre se unió a su mujer Eva, y ella concibió y dio a luz a Caín" using the "se unió a" or "unites himself with", a different sense entirely than "to know" or "to make love". This French version says "L'homme s'unit à Eve, sa femme; elle devint enceinte et donna naissance à Caïn.", using the same phrase "s'unit à". If anyone reads Hebrew, I would be curious as to what the exact word was used here in the original text. Many of these translations use euphemisms for sex which were most common at the time when the translation was fixed ("knew" in pre-20th century translation, "made love" in more modern ones) so I would be curious as to what the exact word was in Hebrew and what that word is translated to outside of this specific context. --Jayron3213:44, 11 October 2012 (UTC)[reply]
I know a little bit of Hebrew, and the word used for intercourse in Genesis 4 does indeed literally mean 'to know'. For example, in Genesis 3, the snake says to Eve 'Ye shall be as gods, knowing good and evil' and likewise 'they knew that they were naked' etc. The same verb ידע is used in all these places. I don't think the euphemism arose in English actually, on the contrary, this manner of speaking was not common in English at the time, it was copied from Hebrew. The reason that many modern translations use 'make love' etc. is because they recognize that 'knowing' in this sense is not actually good English, while older translations like the KJV were much more concerned with translating word for word, and so ended up using expressions that were quite strange and uncommon in the English language. On the matter of it being explicit: it was certainly readily understood, just like 'sleeping with someone' does not literally mean what it infers, but that does not make it ambiguous. - Lindert (talk) 14:03, 11 October 2012 (UTC)[reply]
Interesting. So the euphemism exists in the original Hebrew. Thank you for that insight! What about Genesis 16:1-4 then? Does the Hebrew there say "know" or does it say "go in to" as the translations seem to use? --Jayron3220:07, 11 October 2012 (UTC)[reply]
The verb used in Genesis 16:2&4 is בוא (bo), and means literally to come/go in. Genesis 7:1 'come thou and all thy house into the ark' uses the same Hebrew construction (i.e. -בוא אל) as Genesis 16:4 'And he went in unto Hagar'. - Lindert (talk) 22:02, 11 October 2012 (UTC)[reply]
It makes sense that the euphemism of 'know' for 'have sex' originated in Hebrew because the same euphemism exists in French and Spanish (and I assume other languages connected to historically Christian societies), viz. conocer and connaitre respectively This is sounding more like a question for the Humanities desk; didn't someone already ask this question a few months ago? 24.92.74.238 (talk) 02:29, 12 October 2012 (UTC)[reply]
Promoters are located near the genes they transcribe, on the same strand and upstream (towards the 5' region of the anti-sense strand).
How promoters could be located at upstream in anti-sense strand. Because it is the template strand for transcription. Trascription initiates from 3' end in anti-sense strand. So, promoter should be at 3' (towards downstream region) site of the gene in anti-sense strand. — Preceding unsigned comment added by 117.212.219.234 (talk) 11:25, 10 October 2012 (UTC)[reply]
Defining which strand it's on seems kind of pointless to me. The promoter is as much on the sense strand as it is on the antisense strand. But there is simply not a simple way to describe a promoter. Promoter elements can be located far upstream from the gene start site, or even downstream, inside other genes, and promoters can overlap one another. One of my professor's from college loved to ask at the beginning of every genetics class he taught, "what is a promoter" (or alternatively, "what is a gene"). Someguy1221 (talk) 23:14, 10 October 2012 (UTC)[reply]
Promoters can include enhancer elements that can be distant and not upstream, but the core+proximal promoter is 5' of the coding region, near the transcription start site on the sense strand. "Typical" always has exceptions, but this description is quite consistent. -- Scray (talk) 05:27, 11 October 2012 (UTC)[reply]
The classic exception would be with RNA polymerase III; but usually when people start talking about genes and promoters they're thinking about RNA polymerase II, which handles a huge variety of the "interesting" genes. In any case, there just about has to be something recognizable about some sequence not extremely far from the start of transcription, or else how does it know where to start? At least, I can't really think of a good counterexample offhand, though specific elements like TATA can be absent. Wnt (talk) 01:16, 12 October 2012 (UTC)[reply]
SCIATIC NERVE EXPLORATION
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. Discuss -- Scray (talk) 17:15, 10 October 2012 (UTC)[reply]
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. Discuss -- Scray (talk) 17:15, 10 October 2012 (UTC)--~~~~[reply]
You could try sticking a pin through the bill. Plastic presumably will offer more resistance to penetration than cardboard. However, what is your plan if you can't wash it ? Then you have a dirty, unwashable hat. You really need to make this determination before you buy it, to avoid this dilemma later. StuRat (talk) 19:24, 10 October 2012 (UTC)[reply]
I was wondering which college or university established the first environmental science degree program. Googling, I can find a few programs claiming to "one of the first," but no definitive answer. With several ways to define the question, I'd be interested in (1) the first undergraduate program; (2) the first graduate program; (3) the first program in the US; and (4) the first program outside of the US. --BDD (talk) 19:27, 10 October 2012 (UTC)[reply]
It should be noted, however, that much of sanitary engineering originated as an overt attempt to make people's environment more livable. The entire justification for building the London sewerage system was to improve London's environment; to make it more livable. Of course, most people don't start caring about the Environment until they realize that their environment is becoming harmful to them, but selfish preservation is still one of the primary motivating factors in human action. --Jayron3216:00, 11 October 2012 (UTC)[reply]
Agreed. Most mainstream environmental movements are still about making life better for humans, although there are a few bizarre movements that call for people to go extinct in order to preserve "Mother Earth". StuRat (talk) 21:34, 12 October 2012 (UTC)[reply]
Note also that "environmental science" means different things to different people. Two important branches are (1) the study of how man's actvities affect the environment, and (2) what things man has to do to cope with what the environment provides. Item (1) has attracted much attention in recent years, but item (2) has been studied for much longer, probably at least 100 years or so. For example, Murdoch University in Australia http://en.wikipedia.org/wiki/Murdoch_University has always had (since the University was established in 1975) courses and research in what they call "environmental science" - these have included such things such as novel types of air-conditioning and energy-efficient buildings. Wickwack124.178.43.122 (talk) 00:58, 11 October 2012 (UTC)[reply]
The metric expansion of space only applies to objects that are not bound to each other by gravity. The earth-moon system is bound by gravity, so it is not affected. --Jayron3219:42, 10 October 2012 (UTC)[reply]
It is just a coincidence, and the metric expansion of space is not applicable within gravitationally-bound systems; it only applies well above the scale of galaxies. By way of evidence, consider that the magnitude of Earth-Moon tidal acceleration is impacted by the nature of Earth's oceans, which can play no role whatsoever in Hubble's law. — Lomn19:47, 10 October 2012 (UTC)[reply]
The metric expansion of space does not "expand" bound systems. But I always wondered: It shows up as the cosmological constant in Einsteins equations. Shouldn't it also show up in Newtons equations (as an extremely small modification, of course)? In other words, shouldn't the attraction between two bodies be ever so slightly smaller thanks to it than it would be without it? --Stephan Schulz (talk) 07:25, 11 October 2012 (UTC)[reply]
Well, that makes sense, because we say that "gravitationally bound systems aren't expanding away from each other", but that's a tautology: what it really means is that systems whose force of gravity is strong enough to overcome the metric expansion of space don't recede from each other. Neither the metric expansion of space nor gravity every stops working, its just that they counteract each other so if gravity is strong enough, the net effect is that the objects don't move away from each other. But gravity doesn't have any extinction; it decreases in strength via the Inverse-square law, but it should never drop to zero for any finite (but arbitrarily large) distance. Thus, everything in the universe is subject to "metric expansion", but you only see objects moving away from each other if the objects are sufficiently far apart already as to be under such a weak influence of each other's gravity that the metric expansion becomes the greater effect. --Jayron3215:57, 11 October 2012 (UTC)[reply]
Your comment is confusing some things. By the "metric expansion of space" you really mean changes in the cosmological scale factor. The evolution of that scale factor is driven by three processes, inertia, gravity, and dark energy. Most of the expansion we talk about is really the Hubble flow which is a purely inertial process. Specifically, galaxies expand from each other because at the moment of the big bang the primordial universe was imparted with momentum that is still resulting in expansion today. It is like watching the debris from a bomb going off. At the moment of the explosion, a large impulse is imparted to everything, but afterwards the debris continues flying apart without the need for any additional forces. If we could magically turn off gravity and dark energy, the universe would continue to expand. The second process governing the scale factor is gravity. On cosmological scales the sole effect of gravity is to slow the expansion of the scale factor. In a universe with sufficient mass, gravity would eventually win and the expansion would reverse itself leading to a contraction and eventually a big crunch. We do not appear to live in such a universe. However, in the absence of dark energy all you need to consider is gravity and the initial momentum in order to understand the evolution of everything. In order for a system to become gravitationally bound, it must have already shed whatever momentum existed that would have initially had its constituent parts tending to fly apart. Gravitationally bound systems aren't affected by Hubble flow, simply because they have already overcome it in order to form in the first place. In the pure Hubble flow regime there is no any additional force creating expansion, hence gravitationally bound systems would be completely unaffected by Hubble flow. Dark energy is the third wrinkle to the story. On cosmological scales it imparts a force that tends to increase the scale factor. If we assume dark energy takes the form of a cosmological constant, then it can be modeled in the classical limit as a force directly proportional to distance, i.e. , where the proportionality constant is . For some concrete numbers, the force of the Sun on the Earth is 3.5×1022 N, compared to the dark energy "force" between the Sun and Earth of 0.8 N. In the classical limit, dark energy is always exerting a force, but the magnitude of that force is trivial until you get to cosmologically large distances. Unlike the Hubble flow, which is a passive inertial process baked in at the Big Bang, dark energy is an active process associated with a new force law and one which can create additional expansion. Dragons flight (talk) 20:56, 11 October 2012 (UTC)[reply]
Yes, I was trying to refer to the positive outward pressure exerted by so-called "dark energy" which is real and active, and as you note insignificant in all but the biggest cases, and not the passive "Hubble flow" which is just the residual momentum of the initial Big Bang. --Jayron3221:41, 11 October 2012 (UTC)[reply]
I'm more like my mother than my father
Through nondisjunction, it should be possible, perhaps inevitable, that some child will inherit two copies of some chromosome from one parent, and zero copies of the same from the other parent. Are there any documented cases of such a thing? Thanks. Someguy1221 (talk) 22:28, 10 October 2012 (UTC)[reply]
Hello, I have a small project for a class where I have to find an example of a genetically modified organism, investigate its basis, and give it's pros and cons. However, "the example must be a viable organism, not a plasmid, vector etc". I am limited to GMOs dealing with viral gene therapy.
However, my understanding of viral gene therapy is that genes are inserted into the virus, which is allowed to replicate in other organism to it's benefit (e.g. cancer killing proteins). Doesn't this therefore qualify the virus as a vector (but equally a GMO)? And thus, is not allowed to be chosen as a topic? Many thanks 93.186.23.80 (talk) 00:40, 11 October 2012 (UTC)[reply]
excluding genetically engineered plasmids and vectors (which are produced by the truckload on a daily basis in research labs) "viable organisms" are not restricted to just viral gene therapy. Many crops are now genetically engineered (e.g. see golden rice) The links at the very bottom of that page may also help you. Many genetically engineered animals are used to study the effects of various diseases, drugs and developmental processes. Good luck and have fun.Staticd (talk) 06:07, 13 October 2012 (UTC)[reply]
Morphine in World War 2
In WW2, US soldiers and flyers carried a "syrette" with a metal tube like that for toothpaste containing 0.5 grain of morphine tartrate, connected to a hypodermic needle for administering the drug subcutaneously to a wounded soldier, with no additional dose to be given for 2 hours. 1)(A question for better understanding of historical medical practice, not a request for medical advice:) Is that equivalent to a modern dose of 32.4 milligrams of morphine? drugs.com says that a typical subcutaneous dose for an adult would be only "2.5 to 20 mg every 3 to 4 hours as needed " 2)In the 1977 movie "The Deep," divers find the wreck of "The Goliath," a ship which sank while carrying medical supplies to Europe in WW2, (based on some historical WW2 ship called the Constellation) and the presence of thousands of little glass ampules of liquid morphine excites the interest of criminals. Did Europeans (Brits, French and other non-Axis forces) inject their wounded from single-doseglass ampules (or perhaps at aid stations from multi-dose vials) with separate syringes, or were they supplied by 1940 with syrettes like US forces? (Or were they just expected to tough it out with a stiff upper lip and no morphine?) Thanks! Edison (talk) 03:11, 11 October 2012 (UTC)[reply]
So big, in fact, that a second such dose would have been rapidly fatal (as the GIs themselves used to say, "One for pain and two for eternity"). Which is why the medics would put a big "M" on the wounded man's forehead after giving him morphine (as seen in war movies like Pearl Harbor, Saving Private Ryan, etc.) to make sure nobody else gave him a second dose by mistake. 24.23.196.85 (talk) 06:39, 11 October 2012 (UTC)[reply]
So when it says "0.5 grain," that is the effective dose of morphine, and whether it is in a "tartrate" of a "sulphate" compound is irrelevant? This website says the tartrate is only 87% as potent per mass: [19] . This table has some conversion tables, but when someone gets "morphine" from a doctor or paramedic today, what chemical form is it likely to be? On the web, some sites say that the dose from these same syrettes is only 16 milligrams: ]http://armymedical.tpub.com/md0913/md09130102.htm]. Is that just plain wrong? Question 3)Finally, were these military syrettes stolen or diverted and sold by criminals to civilian drug addicts in WW2 as an alternative to heroin, or would they have been converted to heroin or "cut" with something before being sold to addicts by criminals? Thanks. Edison (talk) 15:43, 11 October 2012 (UTC)[reply]
Tartrate ion has molecular mass of 148.07 daltons, sulfate ion has a mass of 96.06 daltons, and morphine has a molecular mass of 285.34 in neutral form. I think that one hydrogen ion is added to the alkaloid nitrogen in the morpholinium salt (286.35), which means that half a sulfate or tartrate should be needed per morpholinium to balance the charge. That gets us 334.38 for the sulfate (half the molecular weight) and 360.39 ([20]) for the tartrate for the same amount of morphine. However, as listed in the table in the morphine article, the actual drugs are hydrates. (This is an example of why Wikipedia shouldn't be taken as medical advice - I very nearly answered according to the non-hydrated weight, which would, at least hopefully, be technically accurate but quite irrelevant to your historical scenario. Not to mention the stupid mistakes I made in the math trying to calculate per morpholinium rather than per molecular weight, which, in retrospect, was probably not the best way to avoid errors!) The sulfate gets 5 H20 (5 x 18.01528 = 90.0764) (half that per morpholinium) and the tartrate gets 3 H20 (54.04584) making the final weights per morpholinium 379.42 (sulfate) and 387.42 [21] (tartrate). Our article lists them as equal to 0.75 (sulfate) and 0.74 (tartrate) the free base weight of morphine (285.34), which agrees within the level of error in the table. (0.7520, 0.7365). Wnt (talk) 17:58, 11 October 2012 (UTC)[reply]
There are some errors in that table, it has Morphine phosphate (7 H2O) and Morphine phosphate (1/2 H2O) listed with the same freebase conversion factor. I'm not sure if the 0.5 grain would include the hydrate part. I've looked at pictures of the box these came in and it doesn't mention the hydrate. Don't know what the practice was then, but nowadays the dosage applies to the ingredient as it is written. Like 60 mg pseudo-ephedrine HCl, but dexedrine 5mg dextro-amphetamine (without the H2SO4) Ssscienccce (talk) 23:08, 11 October 2012 (UTC)[reply]
I found Medical Services of the Royal Australian Navy who presumably followed Royal Navy practice. "...the question of morphia administration was of great importance . Methods used before the war consisted of individual injections by the medical officers or possibly senior sick-berth ratings, using either tablets of morphine sulphate or hydrochloride in bulk solution from rubber-capped bottles. In addition, Wildey's syringe which enabled four or five doses to be given by the one full syringe was available in some ships. Obviously, however, it would be of considerable advantage in a ship, with its numerous isolated compartments, to have a foolproof syringe which would enable anyone, if the need arose, to give a correct dose to himself or to another. Hence the appearance of a self-giving syringe known as " tubunic " ampoule or syrette. Supplies of this article were very difficult to obtain but finally became available. Three types were used in the R.A.N.: the first from the United Kingdom, the second from the United States, and the third made in Australia . They were not extensively used and on the whole they proved a disappointment, by reason of the frequent collapse of the soft metal container or the blockage or breakage of the needle. The American article appeared to be the best." (p.25) So the US version seems to have been ahead of the game, but not available to Commonwealth forces until late in the war. I found a reference in The British Army 1939-45 (3): The Far East, By Martin Brayley about the Chindit columns that operated in the Burmese jungle behind Japanese lines; "Although it was never spoken of, it is clear that the helpless were often given a merciful overdose of morphine before being abandoned." (p.34) Alansplodge (talk) 17:51, 11 October 2012 (UTC)[reply]
Thanks. Sounds like various allied forces were well supplied with morphine either in large vials for medical officers to administer or with syrettes. I could not find general US or Brit book on field hospital practice in WW2, but did find some brief booklets for frontline medics. Question 4)Any suggestions as to a WW2 vintage handbook for British military surgeons or physicians which would identify other drugs they used in hospital or aid stations in the combat zone which would have had a ready market for pushers to sell to addicts or other illicit civilian users? Edison (talk) 20:43, 11 October 2012 (UTC)[reply]
Why is my voice so much deeper in the mornings, not to mention when I have a cold? I've checked, and it's not my imagination. I've been out of bed for only a little while, and I'm half an octave lower than last night. IBE (talk) 09:27, 11 October 2012 (UTC)[reply]
I think I have a fair idea of the rules. It would be a strange medical condition. It is a fairly common observation in the case of a cold that the voice drops a fair bit. I used myself to show that I had double checked that it wasn't my imagination. IBE (talk) 13:39, 11 October 2012 (UTC)[reply]
Googling for the lower morning voice portion finds a lot of singing sites that primarily suggest that your vocal chords are, after a night of disuse, relatively slack and thickened (analogous to taking the tension out of a guitar string). I have anecdotally observed similar effects when I have a cold, but I don't know what the relevant mechanism there would be. — Lomn14:26, 11 October 2012 (UTC)[reply]
Just personal experience, but the phlegm coating the vocal chords seems to play a role in lowering the lowest attainable pitch, since a good rinse immediately raises it bu a couple of notes.Would a vibrating sting of a certain length and tension sound a lower pitch it it had more mass per unit length? The phlegm or coating could provide that extra mass. Edison (talk) 15:47, 11 October 2012 (UTC)[reply]
It would, that's why guitar strings are different thicknesses. The note a string sounds is a combination of its thickness, composition, length, and tension. They all play a factor. --Jayron3215:52, 11 October 2012 (UTC)[reply]
Searching the web for morning deep voice finds some discussion suggesting that in the morning you are unaffected by the day's mental stresses (don't we all get whiny when we get stressed), and gravity hasn't been shaping your height and your vocal cords. 88.112.36.91 (talk) 16:42, 11 October 2012 (UTC)[reply]
The gravity one is quite interesting: I thought of this, but gravity should shrink your neck (well, slightly) making it a bit thicker, and hence your voice slightly deeper. But I like the whiny voice suggestion. IBE (talk) 17:19, 11 October 2012 (UTC)[reply]
Mine dropped half an octave last time. Strangely, it persisted for about half a day after the cold had basically worn off, so maybe it has more to do with inflation than mucus. IBE (talk) 00:58, 15 October 2012 (UTC)[reply]
Chemical Equilibrium Expression
I have a series of chemical reactions for which I'm trying to develop an equilibrium expression.
(1) A <> B + C
(2) (x)*B <> D
(3) (y)*D <> D
(4) D + A <> B + C
My intuitions says that:
K = K1([B][C])/(A + K4*D*A) + K2(D)/(([B]^x)+ K3([D]^y))
Not addressing the question itself, but for the benefit of clarity to everyone else, I assume "<>" is the equilibrium sign, which can be displayed directly on WP using the {{eqm}} template. So "A ⇌ B + C" displays as "A ⇌ B + C". DMacks (talk) 01:09, 12 October 2012 (UTC)[reply]
October 12
Dot product and cross product
We know "Work = Force x Displacement", where "Work" is scalar quantity and both "Force" and "Displacement" are vector quantity. This means dot product of vectors is scalar quantity. We also know that cross product of vectors is a vector quantity. Suppose, we are given "Power = Force x velocity". Here, both "Force" and "Velocity" are vector quantity and we have to find whether "Power" is scalar or vector quantity. It becomes easy if we have idea that "Force x velocity" is dot product or cross product. My question is how to recognize the given product of vectors is dot product or cross product. Please, also give me some examples where cross product of vectors is a vector quantity. Sunny Singh (DAV) (talk) 12:28, 12 October 2012 (UTC)[reply]
Any quantity is a vector if it is directionally dependent. Does a concept like "power" or "work" have a directional component? If so, it is a vector. If the value doesn't depend on the direction, it is a scalar. --Jayron3212:44, 12 October 2012 (UTC)[reply]
We don't just arbitrarily multiply vectors and then try to figure out what formula to use. We use mathematical formalism to make a simple calculation about a physical quantity we care about. A dot product of two vectors represents the physically meaningful concept of projection. Loosely stated, this calculation measures how "similar" two vectors are; or how closely aligned they are; and it is scaled by the magnitude of each vector. We can also normalize if we are concerned only with geometry, and not magnitude. We often use the scalar result of a dot product to scale another vector, if that represents some physical, useful quantity. The cross-product is a little more unusual, because its physical interpretation is somewhat less intuitive; but simply put, a cross product guarantees orthogonality. There are many situations in physics where that property of vectors has physical meaning - like when we're calculating properties in rotating reference frames; or calculating interactions with magnetic fields, spinning objects, and fluid or particle ensembles. My point is, you decide which calculation you need entirely based on the physics; not just based on arbitrary combinations of your input variables. Nimur (talk) 14:25, 12 October 2012 (UTC)[reply]
Nimur's point is what I was going after, but in less eloquent terms as he puts it. Mathematics is a tool in these cases used to elucidate the physics, not the other way around. The physics of a situation drives what mathemetics we use to help explain it. If a physical quantity has a direction, vector mathematics is used to describe it. If a physical quantity is directionless, scalar mathematics is used to describe it. The question first to be asked when trying to decide whether a quantity is scalar or vector should be "does this physical property depend on direction." --Jayron3216:13, 12 October 2012 (UTC)[reply]
Torque is an example where the cross product is used. The result of the applied force will be a rotation around an axis perpendicular to the force and the lever. Lorentz force is another example: the force on a charged particle in a magnetic field is perpendicular to the direction of the field and to the direction it's moving in (the velocity vector). For a charged particle in an electric field on the other hand, the force will be in the direction of the field. Angular velocity can also be represented as a vector, and the cross product is used here too. One way to decide whether dot or cross product should be used is considering two cases, one with both vectors in the same direction, the other with perpendicular directions. If the result should be maximum for the first and zero for the second, then you would probably use the dot product; in the opposite case, the cross product. Ssscienccce (talk) 10:55, 13 October 2012 (UTC)[reply]
Two questions for project
Does anyone know what structural settings bending folds are most likely to be found in? What about buckling folds? This will be useful in identifying where different structures formed. Thanks.~~--- Anon — Preceding unsigned comment added by 99.146.124.35 (talk) 12:46, 12 October 2012 (UTC)[reply]
From my previous question I realized that malaria was present in Europe some centuries ago, but now it has been eradicated. How could be possible that malaria mosquitoes specifically disappear but that you still get mosquitoes in Europe? What's the difference between one kind and the other? Gorgeop (talk) 14:12, 12 October 2012 (UTC)[reply]
Is genetic resistance to malaria perhaps what you are looking for? Mosquitos are not born with malaria, they need to ingest it from an infected host to be able to pass it on. If a strong resistance to malaria removes the disease from the population, then no amount of vectors will matter since there is no disease to pass on. Livewireo (talk) 14:42, 12 October 2012 (UTC)[reply]
Malaria eradication was very much intentional. We have an article National Malaria Eradication Program for the U.S. - not sure if we have the equivalent for Europe. History of malaria makes an extraordinary claim indeed, that Anopheles gambiae got loose in South America, caused the worst malaria epidemic ever seen in the New World, but was then completely exterminated by eradication efforts within a few years. Which, I have to say, seems more ambitious than programs against invasive species tend to be today, even if they had to use Paris Green (and ordinary Pyrethrum) to do it according to our article - and it was done in northeast Brazil! (Apparently this was just before DDT was discovered to be an insecticide ... not sure if it played a role; certainly it did in other efforts) Of course, those were also the days when "draining the pestilential swamps" was seen as a positive thing. Wnt (talk) 14:59, 12 October 2012 (UTC)[reply]
Generally speaking the major way to eliminate malaria was to drastically decrease mosquito populations (vector control). Historically this was achieved by drainage and later pesticides. By driving down the number of mosquitos for an extended period of time, you can decrease the amount of overall malaria in the ecosystem to basically zero levels, because the malaria parasite cannot reproduce without mosquitos. You will never really get rid of all of the mosquitos, and their populations will rebound, over time, but without the malaria parasites. Mosquito monitoring and control is no doubt still in effect (in the United States, the Centers for Disease Control and Prevention does this); if all mosquito control efforts stopped tomorrow, over time malaria would likely return to Europe and other places it has been "eradicated" from. --Mr.98 (talk) 14:59, 12 October 2012 (UTC)[reply]
Malaria is transmitted by Anopheles gambiae mosquitos and these are not like other mosquitos that are still extant in Europe. It's easier to eradicate this species, since they are not able to "hibernate", therefore, you just have to hit them hard once during the winter, when they are more prone to be eradicated. The eggs that they lay won't be dormant for months and hatch when it's hot again. Summary: it was easier to get rid from malaria transmitting mosquitos in Europe, but others are more resilient. OsmanRF34 (talk) 19:52, 12 October 2012 (UTC)[reply]
The parasite needs certain species of mosquitoes to reproduce and human or animal hosts to spread. Mosquitoes don't live long and will feed only a few times before they die. For the parasite to spread, you need infected persons (or other secondary hosts if the mosquito is a species that feeds on animals as well) in whom the parasite has had time to infect the blood cells, a mosquito of the right species has to bite him and get infected, the parasite needs time to reproduce in the mosquito and then the mosquito has to feed on another person before it dies. Infected people will eventually be diagnosed and treated, so when the infection rate is low, the number of hosts will decrease steadily. Ssscienccce (talk) 12:05, 13 October 2012 (UTC)[reply]
Volume of naphtha
How many British Thermal Units of naphtha can fit into one cubic foot or cubic meter? I have a figure with a specific number of BTUs, and I'm trying to figure out its total volume, so I went to Wolfram Alpha, but all I got was "BTUIT (IT British thermal units) and ft3 (cubic feet) are not compatible." 2001:18E8:2:1020:749C:5B76:1D8E:3D22 (talk) 14:24, 12 October 2012 (UTC)[reply]
Well our article has a density down as "750-785 kg/m3" - with that you can work from a measure of BTU per kg, though actually a direct statement of BTU per volume might be more accurate. (This won't be perfectly accurate in any case because with that much of a density range there must be some variation in composition) Wnt (talk) 15:12, 12 October 2012 (UTC)[reply]
NG-based FT naphtha "higher heating value" - 119,740 btu/gal; 20,488 btu/lb; 47.654 MJ/kg; density 2,651
"[1] The lower heating value (also known as net calorific value) of a fuel is defined as the amount of heat released by combusting a specified quantity (initially at 25°C) and returning the temperature of the combustion products to 150°C, which assumes the latent heat of vaporization of water in the reaction products is not recovered. The LHV are the useful calorific values in boiler combustion plants and are frequently used in Europe.
"The higher heating value (also known as gross calorific value or gross energy) of a fuel is defined as the amount of heat released by a specified quantity (initially at 25°C) once it is combusted and the products have returned to a temperature of 25°C, which takes into account the latent heat of vaporization of water in the combustion products. The HHV are derived only under laboratory conditions, and are frequently used in the US for solid fuels."
Engineering and technical books usually distinguish between the LHV and HHV, as, usually but not always, the LHV is what matters to an engineer. However, it is common in college science texts to just quote a single value without stating which it is, and when they do that, it's the HHV, as it is the HHV that is measured in a simple bomb calorimeter. Ratbone124.178.45.41 (talk) 15:58, 12 October 2012 (UTC)[reply]
Note that the way you asked this Q implies that a BTU is a unit of volume. Instead, I suggest that this would be a clearer Q: "How many British Thermal Units can be generated by burning the naphtha which can fit into one cubic foot or cubic meter ?". StuRat (talk) 18:45, 12 October 2012 (UTC)[reply]
many articles give detailed side effects of DUTASTERIDE and many articles give detailed side effects of ASPARTAME, but no article gives effect of both these taken together.
If an article could be given on this topic of a pointer to the sites where this could be found would be good.
Thanks — Preceding unsigned comment added by 117.223.102.73 (talk) 16:25, 12 October 2012 (UTC)[reply]
Unless this has been studied to see if the combined side effects are worse than just the total of each, there is unlikely to be any such article. And, unfortunately, the number of combinations of two substances is too large for every combo to be studied. StuRat (talk) 19:04, 12 October 2012 (UTC)[reply]
Indeed you have discovered the Achilles heel of "safe chemicals" and drugs in general. One may be reliably safe in tests, but two in combination can be a different matter. The classic example of this is melamine, which is pretty much safe to contaminate/adulterate foods with ... until it meets up with cyanuric acid to form big plates of melamine cyanurate that concentrate and clog up the kidneys.
That said, the odds of any given interaction are, well, "probably very low". And because dutasteride resembles a steroid and aspartame resembles a small peptide, their interactions shouldn't be all that different from interactions of other chemicals within the body ... unless they are. Wnt (talk) 19:51, 13 October 2012 (UTC)[reply]
Is it possible that someone studying our civilization 30,000 years from now differentiates caucasoid, mongoloid, and negroid the same way we differentiate neanderthal, sapien and denisavan? As different species due to the relatively narrow geneome that would exist at the future time?165.212.189.187 (talk) 18:51, 12 October 2012 (UTC)[reply]
I doubt it. A species is defined in sexually reproducing organisms as any group which can reproduce to produce fertile offspring. Clearly this is the case with all humans (even extinct Neanderthals). StuRat (talk) 18:55, 12 October 2012 (UTC)[reply]
Yes, those skeleton types are easily distinguishable, as are others. The "there is no race" POV is based on cultural and ethical, not skeletal arguments. μηδείς (talk) 20:00, 12 October 2012 (UTC)[reply]
I can differentiate tall people from short people based on skeletal morphometry, too (and height has a substantial genetic component); however, the question was about species. Differences in skeletal morphometry do not define species. -- Scray (talk) 20:13, 12 October 2012 (UTC)[reply]
Indeed. Of course there is such a thing as race. But it is not a biologically well-defined concept. I think Medeis has it backwards. The ways that we define races are cultural, and not scientific. The scientific perspective is that the concept of human races (as culturally defined) is not biologically useful or meaningful (e.g. as Someguy1221 describes), not that "there is no race." See Race_(human_classification)SemanticMantis (talk) 20:27, 12 October 2012 (UTC)[reply]
I don't think the OP is arguing in a technical sense that they are separate species, he seems to be using the terms loosely. It is unlikely that future scientists would describe the races as species, since they would see unmistakable signs of interbreeding and intergradation. But the current general types will still be distinguishable to them in skeletons of our age. The differences are much more distinct than just height, white people aren't just black people with light skin. Scientists can and do distinguish negroid type skeletons from caucasoids and mongoloids and so forth all the time. Distinctions politicians and layman make may or may not correspond. Whatever it is that semanticmantis wants exactly to deny it is up to him to describe clearly. Just to say biologist, anthropologists, and other scientists don't make distinctions of race is either false, overly-vague, or a wish. μηδείς (talk) 01:47, 13 October 2012 (UTC)[reply]
Medeis, no is arguing that you can't classify people as being members of a race, nor does interbreeding and integration have anything to do with it. Rather, race simply has no meaning in cladistics, except as a geo-phenotypically defined paraphyletic grouping. Identifying a person as mongoloid carries about as much taxonomic information as pointing out that a dog is black and fluffy. Someguy1221 (talk) 02:00, 13 October 2012 (UTC)[reply]
Well, seriously, no. Telling me someone is a caucasoid tells me a lot more about what to expect about his skeleton and other statistically likely things than does telling me he's black and fluffy. Perhaps the term terrier would be more closely analogous to a "race" than black and fluffy? As for cladistics not applying to races, that will be a surprise to population geneticists and linguistic classifiers [25] for example. I am not interested in this debate, denying the reality of race is a facile way of claiming scientific sophistication. What is important is what is affirmed, not what is denied. We will see if the OP clarifies his statement. μηδείς (talk) 02:19, 13 October 2012 (UTC)[reply]
The graph doesn't refute either of us. You can take literally any group of living things and construct a phylogeny. I don't know how they constructed theirs, so I can't comment on it. I'm not saying that scientists have not worked with racial classifications in phylogeny, I'm trying to say it's not useful. In layman's terms, the group of people described as "mongoloid" does not include all living descendants of the group's most recent common ancestor, by far. In other words, there are people who genetically belong to the mongoloid classification as much as anyone who is phenotypically mongoloid does. There are even people who are phenotypically mongoloid who genetically fit in better with some other racial classification. So going back to my very first comment, the races are paraphyletic groups. If you knew any taxonomy aside from what you randomly googled, you'd know that no taxonomist would ever intentionally construct a paraphyletic group. For the most part, they only exist because many classifications were conceived before sequencing existed (some newer ones exist because species were ordered in a phylogeny before detailed sequencing was done at all). But I will give you one thing, I went too far when I said race is meaningless to cladistics. It has meaning, but I maintain that "mongoloid" is as much a species/subspecies/any-monophyletic-group as "black fluffy dog". Someguy1221 (talk) 03:38, 13 October 2012 (UTC)[reply]
It's also true that there are monophyletic groups that almost contain all of a given race. This is why cladograms like the one you showed, as well as the ones in our own article on the subject, are so easy to make. Someguy1221 (talk) 03:41, 13 October 2012 (UTC)[reply]
Have a look at this [26] recent assessment of human phylogeny. As depicted in the first figure, human races started varying around, oh, 150,000 years ago. That's a long, long time, but it's nothing compared to the 500,000 years separating us from Neanderthals. Remember - Neanderthals persisted until very recent times (relative to that) so they were a new species. Of course, long ago, there was a time when sapiens and neanderthal were brothers in the same family, and there's a time when any two brothers today, or any two races, could be the prototype of a new species. But the races need not be the prototypes for the split - it is just as possible that a single mixed-race population subsequently divides (the nerds of all races at your local high school launch off into space...). Wnt (talk) 22:57, 12 October 2012 (UTC)[reply]
Actually the biggest distinction among current humans is between Bushmen/Pygmies and everybody else. But even there the level of genetic similarity is much higher than between Neanderthals and Modern Man. Regarding Denisova Man, all we have from them is exactly one finger bone, one toe bone, and one tooth, so pretty much everything we can say about them comes from genetics. Looie496 (talk) 23:02, 12 October 2012 (UTC)[reply]
Despite all the pointless arguing, nobody has hit the main point. No, future scientists will not classify today's humans as separate species, because what counts as a species isn't defined based on currently-living humans. The most common definition of "species" is "a group of organisms capable of interbreeding and producing fertile offspring." There is no question that today's humans can interbreed and produce fertile offspring. Therefore, unless scientists decide to redefine species, today's humans are and forever will be the same species. --140.180.242.9 (talk) 10:38, 13 October 2012 (UTC)[reply]
Well, you usually think of the last common ancestor, and if you send some sample humans off in a flying saucer, that last common ancestor has already been born. True, it's very very unlikely, but we can't rule it out.
I am also rather curious about how much interbreeding actually occurs between the Twa or other "pygmies" and the rest of humanity. I've entertained the sci-fi speculation that these small, efficient humans await merely the development of interstellar colonization and 20 generations or so of strong selection to reveal themselves as a successor species to H. sapiens. Wnt (talk) 00:43, 15 October 2012 (UTC)[reply]
The biological species concept is a really fuzzy concept. It's not always the case that a "mule" is sterile. For example, mallards are famous for breeding with any duck they can meet up with, and "contaminating" species in this way. There's even the odd case of ring species, which will freely interbreed along a continuum of terrain ... but act as different species at the ends! At a rough approximation, species are groups of animals that not merely can but do interbreed, or would interbreed... maybe someone else understands the philosophy here more than I do, because at some point I tend to think of the distinction as more semantic and arbitrary than deeply meaningful. I suspect for example that the incredibly rapid African cichlid adaptive radiation events have something to do with the ancestral population being made up of hybrids to begin with.
When it comes to Neanderthals, the record doesn't look like free and open mating between the two populations, but rather some very limited transfers. For example, if you backcross offspring of a rare fertile female mule back into the population, you can transfer some horse genes to the ass or vice versa (I don't know if it works both ways offhand), but it doesn't make the two the same species. Wnt (talk) 19:52, 15 October 2012 (UTC)[reply]
Physical process at work when airing out some smokey clothes?
I went to a social event last night that featured a great deal of smoking. Not a smoker, I was annoyed that my suit reeked of cigarettes when I got home. Without giving it much consideration, I hung my suit outside to "air out" overnight. Then I realized I have no idea what is literally happening during this process, meanwhile the outcome is assumed. What happens to the cigarette scent? The particulates don't just magically jump off my suit, do they? Why does it freshen? The Masked Booby (talk) 01:08, 13 October 2012 (UTC)[reply]
Liquid components can evaporate, solids can either sublimate or be blown off. UV light from the sun may also cause chemical reactions, and other scents (like in pollen) may be deposited on the clothes and then disguise the smoke smell. StuRat (talk) 01:14, 13 October 2012 (UTC)[reply]
The word you are looking for is adsorption, the process by which gases and liquids come to cling to surfaces. There is a thermodynamic equilibrium between adsorption sites and adsorbents in the air. In smoky air, the amount attached to clothing will increase until the adsorption sites are more or less saturated. In clean air, the adsorption sites will slowly and spontaneously release the molecules they have been holding. This causes a lingering odor even after the clothing is removed from the smoky environment. The odor dissipates once all the attached molecules have released from the clothing and had a chance to drift away. When possible, washing the clothing is also generally effective at removing adsorbed odors. Dragons flight (talk) 05:06, 13 October 2012 (UTC)[reply]
Also notice that the reason to hang it outside isn't just to deodorize it, but also to prevent the odor from being deposited on other objects inside. StuRat (talk) 06:30, 13 October 2012 (UTC)[reply]
Why inorganic and + (plus sign)
I am confused why we classify CO and CO2 as inorganic compound even when both contain carbon. My another question is - While reading newspapers I always see + {sign} and some small colorful circles at the bottom of each page, where there is no text. I think these + and small circles have some importance, but I don't know what is that importance. Sunny Singh (DAV) (talk) 09:02, 13 October 2012 (UTC)[reply]
CO2 is also commonly created by organic processes, such as eukaryotic respiration. If you have a room full of chemical scientists, you'll be assured to have more definitions of the term organic than there are people in the room. Plasmic Physics (talk) 12:12, 13 October 2012 (UTC)[reply]
That's probably too rigid. I don't think that any chemist I know would classify Mirex as "inorganic", and certainly PTFE would be counted as organic as well, despite not having any hydrogens. - As Graeme points out below, the reason for the organic/inorganic split is the initial belief in vitalism, where the distinction between organic and inorganic wasn't based on atom composition, but on the (erroneous) belief that the materials that made up life had some "élan vital" that made them different from inorganic ones. The "contains carbon" was a post-hoc rationalization for the split. - Personally, my definition of "organic" is more along the lines of "contains carbon, except for a few historical exceptions". The "contains both hydrogen and carbon" might be okay if you altered it to "contains either carbon-hydrogen or carbon-carbon bonds". (As Plasmic Physics says: more definitions than people in the room). -- 205.175.124.30 (talk) 21:14, 13 October 2012 (UTC)[reply]
I know it's just an opinion, but based on vitalism, it seems silly that as a synthetic polymer applied to frying pans, PTFE is considered organic by most chemists. Likewise, Mirex just doesn't exactly scream organic either. Plasmic Physics (talk) 00:02, 14 October 2012 (UTC)[reply]
I removed your heading, StuRat. Digrpat was answering the second question asked by Sunny Singh— the "+ {sign} and some small colorful circles" are registration marks. Deor (talk) 10:14, 13 October 2012 (UTC)[reply]
I've seen various arbitrary definitions of organic compounds, such as "anything with carbon" or "anything with carbon and hydrogen". It looks like the definition can be different in practice, as I infer from [30], which defines volatile organic compounds as being, well, volatile, and "any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate." I note that this excludes C, CO, CO2, H2CO3, Na2C2, Na2CO3, (NH4)2CO3. So the EPA is excluding even some things with hydrogen, so long as it has an "ionic" character to it, or is part of an ion; but they're not excluding, say, carbon tetrachloride or CFCs without hydrogen. So it's apparently a ... flexible ... definition. Wnt (talk) 20:27, 15 October 2012 (UTC)[reply]
Visual imagination of birth-blind people
Redirect me if this question was asked earlier, but can birth-blind people approximately imagine their daily surroundings, such as apartment they live in? Also, how much correct is a blind person's imagination, can (s)he describe for example a beautiful woman based on clues of his/her life experience?--176.241.247.17 (talk) 09:05, 13 October 2012 (UTC)[reply]
People who are congenitally blind have special skills in mentally-mapping spatial relationships they determine by feel PMID 17368576 and PMID 8124943, but some imagery functions are impaired PMID 11496156 and they don't construct detailed visual mental images in the same way that sighted people do (which can be a hindrance or an advantage, depending on the situation) PMID 16556565. "Beautiful", of course, is at least as much cultural as it is biological. -- Scray (talk) 11:48, 13 October 2012 (UTC)[reply]
Getting an oversized Disk though a circular hole in a bendable material ....
If you have a solid disk (eg like a CD) and you want to get it through a circular hole (eg to get it into a sealed plastic bag) (The plastic is bendable but not stretchable, the disk is rigid) you dont have to have the hole diameter as large as the disk. I know I have tried it.
If you bend the plastic along the diameter of the hole and flex it you can pass through through the hole the larger size diameter disk.
If the whole was infinitely 'flexible' (like a circular piece of string) it could be pulled to make a slit; then, if the circular hole had diameter 'd', clearly the disk could be oversized to a diameter d x pi/2 (approx 1.5d).
But the paper or plastic cannot be moved to give a slit shape... Probably the maximum opening depends upon the 'flexibility of the material with the hole cut into it...
... is there any maths of written in for on this!!??
(The problem has practical purpose as I want to get a flange through a hole into a sealed plastic gas collection bag, link this internal flange to an external flange fitted with a tube to give a gas tight seal - to get a tube for my gas collection bag to get it fit for purpose!)
If the opening of the container is flexible, then we could think about the problem as the circumference of the cross-section of the curved disc (you describe it as rigid, but it can be flexed), which would have as upper bound the cross-section of the flat disc (if d is diameter of the disc and x is the thickness, it would be 2d+2x, but x << d so it's approximately 2d). Curving the disc will, conceptually, shorten one side. Assuming that the disc cannot be curled to overlap, the minimum would be d (with the disc curled around to make a cylinder; obviously, the latter isn't easy with a CD). So, I think the opening needed is bounded by d..~2d, and depends on the flexibility of the disc. -- Scray (talk) 11:35, 13 October 2012 (UTC) Heron is correct in following comment - I reversed the problem. -- Scray (talk) 03:19, 14 October 2012 (UTC)[reply]
Scray, I think you are confusing the flexible plastic of the bag with the rigid plastic of the disc. The disc is rigid. The only reason OP can't stretch the hole into an arbitrarily narrow slit is that the material has a finite Young's modulus that resists bending. If the material were perfectly flexible but inelastic, like very fine chain mail, then you could perform the feat. It only seems impossible because the force required increases to infinity as you approach the ideal slit shape - a bit like trying to straighten a clothes line by pulling on the ends. Maths can help you only by telling you how much force it would take to deform the sheet to a given slit shape. --Heron (talk) 15:40, 13 October 2012 (UTC)[reply]
The material has to be stretchable to some degree for that to work. If it isn't stretchable at all, the only thing you can do with it is fold it, and that isn't helpful. Looie496 (talk) 15:28, 13 October 2012 (UTC) Gah, what was I thinking? Looie496 (talk) 02:59, 14 October 2012 (UTC)[reply]
Agreed, given the constraints of a disk that wont bend at all and plastic that won't stretch at all, the slit in the plastic would need to be as wide as the disk. As far as getting a gas-tight seal, you could try a resealable bag. Those aren't quite a perfect seal, so you might need to add some tape around the edges and corners. You could also use shrink-fit plastic, which shrinks when heated with a blow-dryer. But, again, you may need to use tape to seal up any leaks. And, of course, plastic bags won't hold much pressure, in any case, and will slowly leak small molecules, no matter how well sealed they are. StuRat (talk) 20:54, 13 October 2012 (UTC)[reply]
Hmmm, I'm not absolutely sure that you couldn't expand the slit at all at one point by some deformation of the plastic around the hole that did not involve stretching. That sounds like a non-trivial math problem to me... Wnt (talk) 23:44, 13 October 2012 (UTC)[reply]
Perhaps there's some difference in how we are using the term "stretching". All materials can undergo both elastic and plastic deformation, to some degree, except for a theoretically "perfectly rigid solid" (these don't exist in real life, but crystals come close). Elastic deformation is when a material deforms and then returns to it's original shape. Plastic deformation is when a material deforms but does not return to it's original shape. As the name implies, soft (thermo)plastics tend to have great deal of plastic deformation, but still do have some elastic deformation. I am calling both types of deformation "stretching". Perhaps the OP is not including elastic deformation. In this case, it would be possible to elastically deform some plastics enough to allow a CD to be inserted, and then have the slit reduce back down to the original size. If you make the bag out of an elastic material, you could use a much smaller slit. StuRat (talk) 00:12, 14 October 2012 (UTC)[reply]
Turret milling machine or Universal milling machine..?
Hi I am going to start a new workshop and want to buy milling machine but I want to know which machine will be suitable for me turret milling machine or universal milling machine. My use of machine will be producing flat surface on small jobs of normally 100 X 200 mm. — Preceding unsigned comment added by 14.140.235.82 (talk) 14:02, 13 October 2012 (UTC)[reply]
What will best suit your needs depends on a multitude of factors that we cannot know. Budget? Is this for a new hobby or some sort of small business? What are you going to machine - mild steel, aluminium, special alloys? Plastic? To what accuracy? Do you intend to machine something occaisonally or all day long every day? One would guess from the question that you are a beginner/hobbyist. As such, rather than ask us, a better approach would be to get hold of one or two good trades or hobby level books on machine metal working. Even better, subscribe to journals such as Model Engineer's Workshop for a year or so - you'll learn a lot. Then, join a local hobby engineering group or make contact with an interested tradesman, perhaps someone retired. You question is the sort best dicussed at length with a knowledgable person face to face rather than posting a question to an internet forum. If the highest accuracy is not required, and you only want to do this occaisonally, a better first purchase would be a good pedestal drill. You can fit a low cost X-Y table and milling cutters on a pedestal drill and do quite usefull work at the fraction of the cost of a proper milling machine. However, if your ultimate aim is certainly to end up doing work of professional standard, you should select a machine on the basis of easy upgrade to CNC. Don't forget also, that flat surfaces can be done quickly and very satisfactorily on a lathe, and a lathe can do a lot that a milling machine cannot do. Thats's why there's a lot more hobbyists and small shops that own a lathe as their only machining tool than there are hobbyists and shops that own a milling machine. Are you going to work in plasic, or can the things you want to make be done in plastic? If so, 3D printing is now the way to go. Ratbone60.228.235.209 (talk) 15:24, 13 October 2012 (UTC)[reply]
For that matter, if you only want to make a flat surface in metals such as steel, aluminium, brass, once in a while, say once each few months or more, and you have a good degree of patience, you don't need any powered machine tool at all. The hand method suitable for a job 100 x 200 mm is as follows:-
1. Cut to a slight oversize as best you can with a hacksaw - use a new blade and take it with nice and slow long strokes without forcing it. You should get to within 0.5 to 1 mm of true.
2. Use a coarse double cut barstard file (steel) or dreadnought file (aluminium or brass) to bring the surface to within 0.1 to 0.15 mm, checking with a steel rule. People who have not been properly trained in filling find it difficult not to produce a curved surface - clamping a piece of 30 x 30 square steel tubing to the backside of the file helps - put some shims between the file and the tubing to convex the file surface slightly to compensate for the natural human tendency to curve the work surface the other way. If you find it hard not to curve the work you are probably applying too much force or you have the workpiece to high or too low for you. Finish up by drawfilling with a single cut mill file, being carefull to only "load" the file with fingers over the middle of the workpiece.
3. If greater flatness than +,- 0.1 mm is required, get a piece of float glass to use as a reference surface. Use a can of spaycan paint to apply a THIN coat to one side of the glass. Don't wait for it to dry. Rub the painted surface LIGHTLY on to the work surface. You'll now have paint on the high spots of your work surface. Now, use a hand scraper to scrape metal only where there is paint. Repeat as necessary until the paint evenly coats the work. The professional version of this is to paint the work with marking blue or a felt tip pen and then rub it with a reference flat surface, and scrape where there blue or felt tip has been rubbed off.
An important question is whether or not the OP needs his flat surface to be parallel to, at right angles to, or at some specified angle to, another flat surface on the workpiece. Right angles can be done accurately on the lathe with some care and a dial probe. Right and arbitary angles can be done easily on a turret milling machine. They can only be done by hand scraping if both a reference flat surface and a reference angle block is avalailable. Reference blocks are readily available for right angles but not arbitary angles. Floda 124.178.37.144 (talk) 02:58, 15 October 2012 (UTC)[reply]
Europa from Io
Having read the articles about Extraterrestrial skies and Apparent retrograde motion, here's what I'm wondering:
What would Europa's path look like for an observer sitting at Io's antijovian point? It will return to the same position after two Ionian days, and there will be some sort of retrograde motion, but apart from that, I can't really visualize it.
Retrograde motion only appears when you look at something closer to the center than you are -- not the case here. The motion is quite simple. Let's start with the two moons aligned: Europa appears then at the zenith. For about a day, Europa drops toward the horizon. For about two days it is absent. Then it appears on the opposite horizon, and takes another day to climb back to the zenith. (The motion of Io as seen from Europa is much more complicated.) Looie496 (talk) 15:41, 13 October 2012 (UTC)[reply]
Actually, as I think about it, the apparent motion of Io as seen from Europa is not complicated either. You simply see it revolving around the central planet which remains fixed in the sky -- the apparent speed of revolution is exactly half of the true speed. Looie496 (talk) 17:09, 13 October 2012 (UTC)[reply]
Could you clarify what you mean by "Retrograde motion only appears when you look at something closer to the center than you are", Looie. It's the planets that are farther from the Sun than Earth that appear to have periods of retrograde motion (from our perspective); Mercury and Venus don't. Deor (talk) 22:30, 13 October 2012 (UTC)[reply]
I have to admit that the answer I gave was wrong, because I forgot about the fact that "retrograde" is defined with respect to the stars. On an ordinary satellite that's the only reasonable way to define it, but on a tidally locked satellite like Io or Europa it's a little strange. The fact is, as I said, that if you stand on Io and watch Europa, you will see it steadily rise in the sky and steadily fall, without ever reversing direction. But at the same time the stars also rise and fall. Most of the time Europa is rising or falling faster than the stars, but there is, I should have realized, a short period of time while Europa is near the zenith when the stars outpace it. And that, by the usual definition, is retrograde motion. Looie496 (talk) 14:56, 14 October 2012 (UTC)[reply]
Well, we actually have a sextuple bond article, and it's totally news to me. The diagram in the article makes it look like 5 d orbitals and one s orbital are involved. Searching for "sd5 hybridization" and molybdenum turned up [31], which says it is found in HC(triple bond)MoH3; but I've never heard of sp3 hybridized carbon, say, using all four bonds to interact in a two-atom molecule ... but that's not really quite the same. Hmmm. It should be very interesting to hear a serious inorganic chemist comment on this one. Wnt (talk) 20:26, 13 October 2012 (UTC)[reply]
I'm thinking your list of molecules may be hard to define. For example, grab a lump of elemental metal, any metal, in vacuum. Ta-da, instant "molecule", with a bazillion atoms "bound together" to some degree or other. One can argue that fullerenes fall, very loosely, into this category.
Also, I'm not really aware of a [C=C=C=C=C=C=] ring (benzene contains hydrogen, of course). Diamonds are another type of very very large molecule. Wnt (talk) 20:30, 13 October 2012 (UTC)[reply]
Could you clarify the question, i.e. criteria for inclusion? For example, do you include Boron as you do because of Cs2B12H12? If so, that's not really in elemental form, right? Same goes for benzene, as Wnt asks. If you include these, then do all of the atoms of the same element need to be contiguous? I find the "elemental" version of the question interesting, but then the list you gave must be edited. -- Scray (talk) 20:41, 13 October 2012 (UTC)[reply]
Also, do they have to be neutral? If you type "boron clusters" into NCBI you'll get a lot of references; some discuss anions, however. See [32] and [33] for example. I get the feeling (not sure though) that you can pretty much blast boron into any size fragment you like; I suppose this is true of most elements, unless smaller compounds (like N2) are strongly preferred. Wnt (talk) 20:45, 13 October 2012 (UTC)[reply]
"The current price per package of tasonermin (Beromun 4 vials 1 mg) is EUR11,813.54. "
Come on! How can 4 mg cost that much? If they are protected by patents, is there a black market somewhere for this? It seems economically more attractive to produce such kind of things, being at 2.5 millions/gram than any other illegal drug. OsmanRF34 (talk) 22:33, 13 October 2012 (UTC)[reply]
Monopoly prices are absolutely arbitrary. (For a shining example of contemporary medical ethics, see Colcrys.) Nonetheless, four milligrams of highly purified, active human protein is not something that is really that easy to cook up in a lab. Note that a specific protein, unlike cocaine, isn't something that you can mix up with gasoline and salt and shake out of solution - you have to baby it through the isolation process to avoid protein denaturation. A misfolded protein wouldn't work - I'm guessing it might even trigger some damaging autoimmune response. I'm not that well versed in business to pull out the commercial details from the company, but my feeling is that if you got a graduate student to whip something up in a week in a basement laboratory, it would cost a substantial fraction of the price, and many bad things could happen.
That said, I can picture alternatives and workarounds. Notably, TNF-alpha can be induced by things like gram (-) endotoxin [34], which is undoubtedly vastly cheaper and more available, though that of course can (will) induce other cytokines in a different pattern than the purified cytokine. From [35] note also that diet affects TNF-alpha production - more omega-3 fatty acids lead to less production in blisters. (I suspect that "dry" cupping therapy is a practice which will be reexamined in the near future, for this and some other reasons e.g. thymosin - the fluid produced by blisters is a who's who of potentially therapeutic proteins, though in other cases they are undesirable. Maybe that's nuts, but then again, I was the only person I knew in the 90s who was soft on Lamarckism :) ) But there are many, many ways to get TNF-alpha production to increase, and I probably haven't thought of the best here. My guess, in short, is that a black market in purified TNF-alpha is not very feasible. Wnt (talk) 23:24, 13 October 2012 (UTC)[reply]
That sounds about right, actually. If I want to buy 4 mg of recombinant human TNF for the lab tomorrow, that'll cost me £7200 from Peprotech (my usual cytokine supplier). And that's research quality, which didn't need to be qualified for clinical use. In this case, there isn't even a patent on it, although there probably is one on tasonermin specifically with regards to formulation etc etc. Recombinant proteins are expensive any way you look at it. As for using something else to increase endogenous TNF production, good luck in finding something that specifically upregulates TNF production without changing any other cytokine levels. (Hint: don't bother, it doesn't exist) Fgf10 (talk) 08:56, 14 October 2012 (UTC)[reply]
OK, but along the production line, where does the money goes to? In this case, no patent, as stated above, so? Machines? Technical personal? Long cooking process? Necessary extraction from humans? OsmanRF34 (talk) 21:41, 14 October 2012 (UTC)[reply]
Ooh, now that's tricky question! First off, it's not extracted from humans (haven't checked this specific one, but in general). These sort of things are made by inserting the human TNF gene in a bacterium or yeast, which is then grown in massive bioreactors. It won't be a very labour intensive process, so that probably won't be the main expense. The consumables for purifying the protein from the bioreactor will be a big chuck of the cost. The thing to remember as well is that 4 mg might seem like next to nothing, but in the world of recombinant proteins, it's an absolutely massive amount. For research use, your normal order would be in the order of 10 to 100 ug.
Of course overhead and near-monopoly pricing has a lot to do with the final price as well. To be honest, I doubt anybody who doesn't work for a biotech company who makes stuff like this can give a sensible answer here (and they wouldn't of course. I will note however, that prices (outside clinical use at least) are flexible, for instance, the £7200 I quoted further up is the list price, for such a bulk order I would expect to actually pay between a quarter or half of that price. Sorry for not being able to give a more conclusive answer. Fgf10 (talk) 07:15, 15 October 2012 (UTC)[reply]
Agreed. Another component of the pharmaceutical price has to be maintenance of a liability fund - litigation with biologics is pretty common and expensive in some markets. You mentioned the costs of production for clinical use: GMP. -- Scray (talk) 08:56, 15 October 2012 (UTC)[reply]
I should revise my statement above to some degree - it might be a bit more feasible... also less so. The similarity in price between lab TNF and the pharmaceutical seemed suspicious ... looking up the Beromun tasonermin, I find that it is actually a non-glycosylated recombinant protein from E. coli, a trimer of three peptides - it's not being produced in the fancy way that nature does it, i.e. TNF that's been inserted into the membrane, covalently modified, and chopped free by an enzyme. [36] It turns out that the human TNF doesn't actually have any glycosylation site. [37] Being grown in bacteria makes it cheaper, and potentially easier to pirate than I'd thought, though still by no means easy. The amino acid sequence used matches aa 77-233 of the human reference sequence [38] - VRSSSRTPSDKPVAHVVANPQAEGQLQWLNRRANALLANGVELRDNQLVVPSEGLYLIYSQVLFKGQGCPSTHVLLTH TISRIAVSYQTKVNLLSAIKSPCQRETPEGAEAKPWYEPIYLGGVFQLEKGDRLSAEINRPDYLDFAESGQVYFGIIAL - that's the same C-terminus at the end, and the same ADAM17 site as in the normal human form. I note that there's a different site at 79 used by MDC9 in vivo,[39] but I haven't looked up if that's a significant amount in the natural version (and it might not have the desired drug activity).
The other problem is that "The clinical indication for Beromun is - as an adjunct to surgery for subsequent removal of the tumour so as to delay or prevent amputation, or in the palliative situation, for irresectable soft tissue sarcoma of the limbs, used in combination with melphalan via mild hyperthermic isolated limb perfusion (ILP)." Maybe it has other indications now, or someone has an off-label use for it, but obviously, you'll have a hard time selling it to the sort of "specialised centres" that they say should be performing the procedure, and if somehow you do, well... the patients will never know about it. I wonder if people who actually care about a stray $15000 are really going to get this treatment anyway...
This approach more generally is based on Coley's toxins, a practice from the 19th century which still fires the imagination. There is such an array of potential cytokine stimulants, tumor antigens, and adjuvants that could interact to enhance an immune response - and immunology remains such a dark art - that to this day the approach offers people at least small doses of hope. Wnt (talk) 13:54, 15 October 2012 (UTC)[reply]
Well, the structure of the recombinant sounds pretty similar to the native protein, that's a homotrimer as well. The fact that's it's not cleaved from the membrane doesn't really matter, as that's not the active form anyway. The homology of the used protein is pretty good, and it will obviously be active in humans, or it would never have come anywhere near the market. The relevant datasheet[40] from the European Medicines agency, (which Wnt already linked to), actually describes the manufacturing process relatively detailed, and it's easy to see where the money goes, as it's pretty complicated. As for their indication, (without reading through the whole thing, admittedly) I can see it working in some tumours (those expressing high levels of TNFR1), but it's a very blunt approach to say the least. Certainly not going to be mild on the side-effects. On an entirely unrelated note, I was just doing some Western blotting on Wnt signalling components today, amussing to see Wnt commenting here as well.... Fgf10 (talk) 15:39, 15 October 2012 (UTC)[reply]
October 14
Hypnosis and alcohol blackouts
Can hypnosis aid in recovery of the memories lost to a blackout drunk? What I've read suggests that they're never properly stored, thus leaving nothing to recall in the first place, but has anyone compared the accuracy of recovered memory to impartial evidence (recordings, etc.)? And if so, what did they find? 71.248.115.187 (talk) 00:29, 14 October 2012 (UTC)[reply]
It's really unlikely that there would be any data specifically addressing that question, because I can't imagine that an Institutional review board would ever approve a study that involved inducing blackouts in subjects. That being said, this is an area where I'm sort of an expert, and my best guess is that there would never be any substantial recall, but it's possible that elements of the experience could be brought back by providing the person with cues that are associated with them. That's what often happens when you deal with people with amnesia, anyway. I doubt that hypnosis would be helpful. It could easily make the person invent pseudo-memories and believe that they are real memories, but if you are looking for genuine memories, those pseudo-memories would just get in the way. Looie496 (talk) 02:37, 14 October 2012 (UTC)[reply]
Recovered-memory therapy is probably quite relevant. Just btw, there are many different study designs which would not necessarily need to "induce" a black out. Case-control study, prospective and Retrospective cohort study could all gather completely relevant data specifically addressing this question. Louie's referring no doubt to the "gold standard" of trials, a double blind Randomized controlled trial, which I agree would probably be tricky to get passed by a ethics review board. And I completely agree with his conclusion, sounds highly implausible. Hypnotism is a widely misunderstood topic. Vespine (talk) 21:46, 14 October 2012 (UTC)[reply]
Does Capsaicin harm plants or their roots?
I have some houseplants I like to keep outside until first frost, but I have a problem with squirrels digging in their pots to the point of entirely uprooting some. I have tried capsaicin in small amounts before (cryy powder) but this wasn't enough to deter them. I am thinking of going all out with some chopped jalapenos or mustard powder on the soil, but am afraid I may hurt the roots. There are a few anecedotes on the web and a high school student experiment with sunflowers that say there will be no effect on the plant. Any good sources that will confirm this, especially on the roots? Thanks. μηδείς (talk) 16:49, 14 October 2012 (UTC)[reply]
Lots of links at Google "Capsaicin effect on plant roots". Never mind, of course you've already done that :-) hydnjo (talk) 19:27, 14 October 2012 (UTC) c/e strike by hydnjo (talk) 19:49, 14 October 2012 (UTC)[reply]
As far as next year, you might want to consider a physical barrier to the squirrels. One method is to hang them from trees using a long wire. Some type of cage around pots on the ground might also work (perhaps a birdcage) ? StuRat (talk) 19:49, 14 October 2012 (UTC)[reply]
Well, I like your idea of hanging the squirrels from trees using a long wire. But a cage around the plants somewhat defeats the purpose. (They are poinsettias I keep over the summer and reflower each year.) μηδείς (talk) 19:58, 14 October 2012 (UTC)[reply]
These plants are at a relative's in NJ, the idea of cages wouldn't go over too well, although a small cage with a much smaller-leafed and spreading flowering plant might actually be attractive. I'll post a picture of my favorite after it begins to flower. The main problem is that these are the only potted plants in that yard that don't spread out over the soil (they have a small tree-like growth form) and with the bare soil they are the only ones the squirrels pick on. So far no disasters this year, but in the past they have knocked them over and split the plants, which are brittle, in half. μηδείς (talk) 21:03, 14 October 2012 (UTC)[reply]
The plants I have in mind are kept in pots, moved outdoors in March, and indoors at the end of October, and replanted yearly. I have already moved the last one indoors this afternoon, on the assumption that the two extra weeks I might get outside will not be worth the work, cost, and risk. μηδείς (talk) 23:21, 14 October 2012 (UTC)[reply]
I just wanted to mention how successful and popular StuRat's suggestion to hang the squirrels from trees using a long wire has been. Three relatives, a loved one, and two local librarians (they buy huge poinsettias yearly, and I have convinced them to take them home and reflower them rather than throw them out) have all broken out laughing when I relayed his advice. μηδείς (talk) 21:48, 15 October 2012 (UTC)[reply]
I've had my own run-ins with squirrels. One came down my chimney, made himself at home, found a loaf of bread, chewed it up and formed it into little balls. He apparently planned to take them back up the chimney and store them for winter, before I came home and, with great difficulty, ejected him from my house. On the plus side, I seemed to scare him enough not to try that again. StuRat (talk) 02:49, 17 October 2012 (UTC)[reply]
Honors thesis project
I am currently researching coastal armoring for my Honors Thesis. I am looking to expand this Honors Thesis into a senior project that I can present at the Northeastern Geological Society of America conference. I still am in the process of creating a thesis statement for the project. Does anyone have any suggestions, specifically about what questions or issues about coastal armoring (particularly in Connecticut are the best to explore? I intend on doing fieldwork of my own for this project. Thanks.--99.146.124.35 (talk) 18:26, 14 October 2012 (UTC)anonymous[reply]
It would have been helpful to explain what coastal armoring is. Apparently it's methods used to prevent shore erosion. I would think a cost/benefit analysis of various methods would be a good thing to study. That is, which methods are more economical than simply abandoning the shoreline and moving inland ? Another option is to look at the effects of global climate change on shore protection efforts. I suspect that methods formerly used are no longer effective when faced with rising sea levels and increased storm intensity. StuRat (talk) 19:08, 14 October 2012 (UTC)[reply]
How about: which zones are more prone to erosion than others; which are zones are most important to protect, from an environmental perspective, and from an infrastructure perspective; is it economical to have your cake and eat it, if not what compromising schemes are available that balances both? Plasmic Physics (talk) 23:22, 14 October 2012 (UTC)[reply]
My first thought is, how does greenhouse effect interact with coastal armoring, especially if the collapse of major ice shelves occurs more quickly than imagined? There is a paper [41] which makes a number of recommendations for "federal/regional government actions", e.g. "Congress should amend the Coastal Zone Management Act (CZMA) to require relevant state agencies to consider sea-level rise in coastal management plans in order to qualify for federal funding assistance; prohibit federal subsidization of infrastructure development and coastal armoring in areas subject to sea-level rise; and encourage public and private land acquisition of coastal habitats and upland buffers." I'd think your project might explore whether the list of actions recommended by the organizations that produced this report for Florida are things which Connecticut should endorse or oppose. (I have absolutely no idea at all myself) Wnt (talk) 00:27, 15 October 2012 (UTC)[reply]
How about the economical difference between manual replenishment with bulldozers and temporary pumping rigs versus a permanent replenishment system similar to water or sewer systems? Usually there are certain places that always get the extra sand and places that always lose it.165.212.189.187 (talk) 13:04, 15 October 2012 (UTC)[reply]
I've read that magnetic motor is impossible due to magnetic equilibrium, but in this video for example a computer cooler seems to spin very well due to repulsion between magnetic poles (that is, one pole interacts with several opposite ones, constantly pushing them). I've browsed the internet further, but still don't get why the magnetic repulsion cannot be used as a source of free mechanical energy (especially considering strong magnets).--176.241.247.17 (talk) 21:41, 14 October 2012 (UTC)[reply]
Magnets apply a force, but force is not energy. This is a distinction which can be very counterintuitive and there are many people who have spent a LOT of time pursuing the futile dream of extracting free energy from a magnet. Our Free energy device article has a section which discusses magnets. Vespine (talk) 23:52, 14 October 2012 (UTC)[reply]
Flooded skyscrapers
In the movie A.I. Artificial Intelligence, Manhattan is flooded due to global climate change. However, the top floors of at least one skyscraper continue to be occupied. My quetions:
1) I assume that flooding existing skyscrapers would quickly cause the supports to rust out and fail. Is this correct ? How quickly ?
2) Is there a cost effective way to retrofit the existing supports to make them survive ? Some type of waterproofing ?
It was an artistically appealing image. Corrosion to failure should take decades, at the most.[42]. Why would anyone with the resources to do so retrofit those buildings a portrayed in that movie? μηδείς (talk) 23:16, 14 October 2012 (UTC)[reply]
Well, if they could be retrofitted at a lower cost than creating new buildings, that would be a reason. Or, in the case of significant historic buildings, they might be preserved even if this costs more than rebuilding. StuRat (talk) 23:19, 14 October 2012 (UTC)[reply]
You might want to link to an article on contemporary retrofitting. I don't think you'll find much on the history of retrofitting in the distant future. μηδείς (talk) 23:59, 14 October 2012 (UTC)[reply]
It's a sci-fi scenario, so there are a lot of possibilities. For example, you could produce some sort of nanobots that home in on sources of dissolving iron and chemically modify any exposed surfaces to passivate them. Or at least you might have more convenient drones for working underwater that you can use to rustproof the exposed materials more easily. There's also the simpler possibility that stronger fireproofing materials that have been or will be developed in the wake of the September 11th attacks turn out to be so tenacious that they block water corrosion as well as a bonus. Wnt (talk) 00:31, 15 October 2012 (UTC)[reply]
It's a sci-fi scenario, so it's asking for speculation, opinion, and debate, and it should be hatted. We have no relevant references. μηδείς (talk) 00:33, 15 October 2012 (UTC)[reply]
Just because you don't have a source, that doesn't mean there isn't one. Note that numerous sci-fi scenarios, like communications satellites, later became reality. StuRat (talk) 00:41, 15 October 2012 (UTC)[reply]
So, in the future, buildings that are already standing today, will become corrosion resistant because...it's the future? Let's just please provide some refs if we're going to continue this one. μηδείς (talk) 00:45, 15 October 2012 (UTC)[reply]
A lot depends on how much flooding you have in mind, and probably also the rate of flooding. I don't recall the scenes in the movie that you are referencing, so I'm not sure what scale of inundation you have in mind. Defending against 2 to 6 feet of sea level rise (typical projections for this century if global warming continues), probably could be accomplished with sea walls, pumps, and other basic barriers. However, complete melting of Greenland (20 ft of sea level equivalent) and Antarctica (200 ft equivalent), would seem very hard to fight against. On the other hand, humans do build oil platforms over 250 ft that are fixed to the sea floor (as opposed to the floating ones used in very deep water), so the idea of skyscrapers that are grounded hundreds of feet under water probably isn't impossible, though I wouldn't want to speculate on what issues would be involved in such a conversion. Dragons flight (talk) 01:29, 15 October 2012 (UTC)[reply]
Possible, but doesn't seem very feasible to me. For one, you end up with a large volume of plant matter containing a small percentage of heavy metals. What do you do with that ? StuRat (talk) 23:15, 14 October 2012 (UTC)[reply]
Then you risk releasing some of those heavy metals into the air. Mercury vapor, for example, is bad stuff. There's also the risk that insects or animals will eat the plants, at which point the heavy metals enter the food chain, which is exactly what we want to avoid. StuRat (talk) 23:20, 14 October 2012 (UTC)[reply]
More specifically Phytoextraction process describes pretty much exactly what the OP is asking about. Burning it might be the best thing to do in some specific isolated cases, but I doubt it's a good idea as a rule of thumb. Vespine (talk) 23:21, 14 October 2012 (UTC)[reply]
Is there a plant that concentrates mercury? I have heard of those that do arsenic and copper. Surely this would be done industrially, and not in back yard barbecues. μηδείς (talk) 23:26, 14 October 2012 (UTC)[reply]
No terrestrial plants naturally concentrate mercury to a significant degree. There are currently efforts at multiple laboratories to engineer such plants with genes from bacteria that metabolize organic mercury (the bacteria use this to salvage hydrocarbons). In theory, this would cause inorganic mercury to concentrate in the plants, and it seems to work in the lab: [43]. Someguy1221 (talk) 23:56, 14 October 2012 (UTC)[reply]
Maybe no terrestial plants, but Plankton certainly concentrate mercury, a casual search has not revealed to me if that also specifically applies to phytoplankton, or any other members which might be considered "plant", (if there are any). Vespine (talk) 23:58, 14 October 2012 (UTC)[reply]
What if the the deposits the polutant in nodule-like growths, which renders it inert? The plant would ideally act as a molecular pump, not simply as a spunge. Plasmic Physics (talk) 01:34, 15 October 2012 (UTC)[reply]
Nice idea. If we could do that, we could also finally mine seawater, bΝy having those plants collect all the substances we want and sequester them in those nodules for us to collect later. Get those genetic engineers to work ! StuRat (talk) 05:25, 15 October 2012 (UTC)[reply]
Maybe not sponges (not sure) but sea quirts have vanadocytes which concentrate the metal to an extraordinary degree. Of course, that's only a few cells, and so it isn't really economically feasible as encountered, yet... it inspires the imagination. Wnt (talk) 14:01, 15 October 2012 (UTC)[reply]
In my comment, I was not refering to Porifera. I as refering to the final destination of the polutants - by "as a sponge", I was refering to the polutant remaining inside the cells, poisoning them. The second scheme, which I suggested, is for the polutant to be transported and sequestered from the cells at a common destination, leaving the plant unaffected. A sponge can only absorb a limited amount of water before it becomes fully saturated, a pump can transport as water as long as it is supplied with energy. Plasmic Physics (talk) 06:48, 16 October 2012 (UTC)[reply]
The earlier thread Malaria in Europe mentioned that malaria had been essentially eliminated in Europe and North America during the twentieth century. I hadn't realized that there had been that much success in eliminating malaria in regions where it had gotten established. My question is, how different is malaria in Africa from malaria in other places? Do differences such as climate and different mosquito populations make it much harder to fight in Africa? Or is it more a matter that the economic resources aren't available to fight malaria in Africa? If I had a huge sum of money (say $100 billion) and complete freedom to go anywhere in Africa and employ the same aggressive techniques that worked previously in the US and Europe, would that be enough? Could you wipe out the malaria bacterium, or is there some reason why techniques that worked in the past couldn't work in Africa? Dragons flight (talk) 02:40, 15 October 2012 (UTC)[reply]
Malaria spreads when a mosquito bites an infected person, after which the plasmodium gametocytes differentiate, then reproduce. Then the mosquito has to bite someone else and rub off enough protists to get them sick. If malaria patients can afford to stay at a hospital until they're treated, where there are presumably fewer mosquitoes, that hampers the plasmodium lifecycle much more than if they had to continue working outdoors. --140.180.242.9 (talk) 05:59, 15 October 2012 (UTC)[reply]
The most effective methods used in the past were A) completely draining all standing water from a region and B) carpet bombing an area with DDT. Both methods are unpopular nowadays, in addition to the longstanding lack of any financial incentive to ridding Africa of malaria. I also suspect that the environment in sub-Saharan Africa is far less tenable to both methods, due to the sheer amount of warm, wet land. Someguy1221 (talk) 09:04, 15 October 2012 (UTC)[reply]
$100 billion wouldn't begin to do it. Africa contains on the order of a million square miles of prime mosquito habitat. Note that malaria is also endemic throughout much of South America, which contains more millions of square miles of prime mosquito habitat. Looie496 (talk) 16:08, 15 October 2012 (UTC)[reply]
That works out to $100,000 per square mile. Is that really not enough to spray a square mile with DDT, especially if you employ natives at the local pay rate (and contribute to the local economy in the process) ? StuRat (talk) 06:47, 17 October 2012 (UTC)[reply]
Baumgartner vs Kittinger
Trying to put Felix Baumgartner's jump into perspective, without all the media hype. Some questions:
Why did it take more than 50 years from the previous height record of Joseph Kittinger? Is it so much more difficult to reach heigher altitudes or is it rather a lack of scientific value (of taking people up there) combined with the cost involved? Were there any attempts at breaking the record of Kittinger before?
What is the main achievement or difficulty to overcome in the Baumgartner dive?
2) Take your pick: high speeds, cold temps at the start, high temps when first hitting thicker atmosphere, lack of air pressure, etc. StuRat (talk) 08:18, 15 October 2012 (UTC)[reply]
2) Yes, but Kittinger had the same, so my question is, whether there is any additional factor to take into account for Baumgartner which did not matter for Kittinger. Adding 3) Did Baumgartner and Kittinger use essentially the same tools and techniques, i.e. is the only difference that Baumgartner had more modern tools/better materials? bamse (talk) 08:27, 15 October 2012 (UTC)[reply]
Adding 4) It is often claimed that it is the first supersonic flight of a human without "vehicle". On the other hand, Baumgartner was naturally not on his own but in a "suit". How much does this suit differ from a supersonic "vehicle"? bamse (talk) 08:30, 15 October 2012 (UTC)[reply]
The most obvious difference is that the suit had no propulsion system - the speed attained was due to gravity's acceleration, making this qualitatively different from powered flight. As far as risks, I was under the impression that there were many - among the greatest being a flat spin resulting in circulatory derangement, loss of consciousness, death. Recovering from such a spin can be hard in a vehicle that has control surfaces and an engine, but Baumgartner just had his arms and legs. I'll try to provide a ref in a little while - I'm sure there are suitable ones. -- Scray (talk) 08:46, 15 October 2012 (UTC)[reply]
In February 1966 Nick Piantanida did in fact go higher than Kittinger, and also higher than the officially planned height of Baumgartner but not the actual height. However, Piantanida didn't make the planned jump and didn't return with the balloon either but in the gondola with a large parachute. Our article has a poor description of the February flight. Click "Long Description" at [44] to see what happened. PrimeHunter (talk) 00:06, 16 October 2012 (UTC)[reply]
Like most scientific knowledge, this was a gradual development, as scientists began to formalize their understanding of experimental results. I'd start by reading our article on thermodynamics, especially the history section. For example, it's doubtless that Isaac Newton had a pretty good idea that friction slowed objects in real systems; and by the time Carnot wrote about formal engine thermodynamics, he stated the laws of thermodynamics outright. If you run farther back into history, Aristotleian physics was simply wrong, and Aristotle asserted the existence of perpetual motion machines without evidence. So, somewhere along the way, we figured out that perpetual motion didn't exist, and gradually made our explanations more clear and consistent with all other physical law. Nimur (talk) 15:04, 15 October 2012 (UTC)[reply]
The impossibility of perpetual motion is a direct consequence of conservation of energy. That principle was first clearly formulated by Hermann von Helmholtz sometime around 1850. So there couldn't have been a really compelling rejection of perpetual motion before that time. However, as our History of perpetual motion machines article says, "In 1775, the Royal Academy of Sciences in Paris made the statement that the Academy "will no longer accept or deal with proposals concerning perpetual motion." The reasoning was that perpetual motion is impossible to achieve and that the search for it is time consuming and very expensive."Looie496 (talk) 16:03, 15 October 2012 (UTC)[reply]
I, personally, do not think that a perpetual motion machine of the second kind, which does not violate energy conservation, is impossible though, because I've figured out how to build one. With it, the empirical second thermodynamic law is no longer an obstacle (its scope being severely limited, of course, by virtue of the existence of my process, which I claim) and we can therefore get rid of fuels and put a stop to global warming. -Modocc (talk) 17:32, 15 October 2012 (UTC)[reply]
I fear that making my work public is thorny though, for a provisional patent and a subsequent public disclosure is not always adequate with regards to the all important step of reduction to practice. I have to be careful to include all the necessary details (unlike Fermat's scribbles). -Modocc (talk) 18:13, 15 October 2012 (UTC)[reply]
Unfortunately the US Patent Office has a policy of requiring a working model before granting a patent for a perpetual motion machine. Looie496 (talk) 18:32, 15 October 2012 (UTC)[reply]
Ah, I found what you were referring to. The US patent and trademark office specifically requires perpetual motion machine applications to be accompanied by a working model, due to their tendency to be full of shit. Perpetual motion#Patents. Patents are still occasionally granted to such "inventions", however. Why, I don't know. Someguy1221 (talk) 23:47, 15 October 2012 (UTC)[reply]
Probably because patents are granted for all sorts of complete nonsense. A patent means nothing until it is tested in court. And if the patent holder can convince someone to buy the rights, well and good, regardless of whether the patent is truely valid or not. It is not the patent office's problem if you have wasted your money getting a patent that makes no sense or has no commercial value. The US Patent Office's decision on obvious perpetual motion devices probably arose from a desire to avoid dealing with complete wankers or perhaps a public service desire to prevent retards wasting their money. An example of a patent that is just as much nonsense thermodynamically as perpertual motion is US Patent 4945866, Altered Piston Timing, Bertin R Chabot, published 08/07/1990, describing an internal combustion engine in which the center line of each cylinder is offset from the rotational axis of the crankshaft in the direction of rotation. This patent is an amazing collection of nonsense claims showing a total lack of understanding of basic thermodynamics, but the idea gets represented under different titles and wording every 10 to 15 years or so. An example of a patent that does not violate basic thermodynamic principles but has no commercial merit whatsoever, a fact that is obvious at a glance to any engineer (it's full of flat surfaces and parts that can't be cooled, for a start), is the Sarich Engine. An example of a patent that is clearly invalid due to prior art is the Dolby noise reduction patent - it never the less was a huge commercial success due to excellent marketing. Ratbone121.215.28.169 (talk) 00:40, 16 October 2012 (UTC)[reply]
A working model is needed for acceptance by the examiner. But, that only establishes its patent-ability to the patent office's satisfaction, subject to its appeals process, but the date of the examination (as with all appeals) will differ from the date of reduction to practice which will be earlier, and as you have pointed out, needs not be the date a working model is completed. -Modocc (talk) 00:21, 16 October 2012 (UTC)[reply]
That shouldn't be a problem, for I'm fairly certain that provisional patent application(s) can establish a reduction of practice, as long as it specifies how to build the working model that is submitted at a later date. My fear is that I may leave out some minor detail with my application(s) that prevents this. Similarly, should I consider simply putting it into the public domain anywhere with a full public disclosure, but this disclosure happens to be slightly incomplete or needs slight correction, it may not be considered a reduction to practice, and whoever recognizes such mistake(s) and fixes these with some mere paperwork may claim the invention! This is therefore a difficult dilemma for me to resolve. Also, further complicating matters, my skills (my eyesight is deteriorating and I'm getting too impatient to stay focused on my work) at actually building the machine are very limited too, but it is simple enough that I am in the process of building it (the parts and tools I've needed for it has cost me less than eighty bucks, but lately its been languishing on my desktop, as its only partially assembled). I've got to do more... -Modocc (talk) 18:47, 15 October 2012 (UTC)[reply]
Our speed in day vs night
Since we travel at 1674k/h around the earth and the earth travels at 108000k/h around the sun, during the day we travel 3300k/h slower than at night relative to the sun. Does this have any noticeable effect on anything?165.212.189.187 (talk) 14:58, 15 October 2012 (UTC)[reply]
(ec) I first thought that ths might have an impact to aiming large telescopes; aligning the telescope and compensating for Earth's rotation would require some added complexity in addition to a standard equatorial mount. But I'd never heard of any telescope using such a compensation, so I went looking through the webpage of the largest telescope that came to mind: Control Systems for the 30-meter telescope. Everything is adaptive and closed-loop control now; atmospheric compensations, laser guide stars; and so on. These telescopes use feedback control to drive the scope the exact optical center of their imaging target. It's not clear from this high-level overview whether those mechanisms and algorithms explicitly include a correction factor for sidereal / solar rotation deviations; but it seems like that would be either unnecessary or superfluous given the already elaborate system. My suspicion is, if you work the math, the angular error to a distant object is negligible, whether you account for Earth's revolution around the sun or not; but you should be able to work out the math and see exactly how tiny that non-zero deviation actually is, and you can even calculate the error as it changes during a single day or night.
In other contexts, satellite communications require complicated doppler shift compensations, and the rotation of the planet should be included in this compensation. I once knew a guy who bounced a signal off of Mars, and the return echo sounded like a descending whistle. I can't recall which time-varying doppler shift was responsible for that; but I sort of seem to recall that it was the rotation of the transmitter on the surface Mars that caused it. I'll try to dig up the actual publication, which should explain the details with a bit more scientific rigor. Nimur (talk) 15:20, 15 October 2012 (UTC)[reply]
Chloroplasts...evolved about 1.6 billion years ago when one cell, incapable of using the sun's energy, engulfed another cell -- a cyanobacterium -- that could. That cyanobacterium became the ancestor of every living chloroplast.
All chloroplasts are thought to derive directly or indirectly from a single endosymbiotic event (in the Archaeplastida), except for Paulinella chromatophora, which has recently acquired a photosynthetic cyanobacterial endosymbiont which is not closely related to chloroplasts of other eukaryotes.[4]
And the abstract of citation [4], which is all I can access, says:
There is accumulating evidence to support a single primary origin of plastids from a cyanobacterium (with one intriguing possible exception in the little-studied amoeba Paulinella)
(a) In layperson's terms, what is the nature of the evidence for a single originating event?
(b) Isn't this single-ancestor assertion highly implausible on the face of it? It seems that if conditions were amenable for this event and its propagation at that time, it would have occurred numerous times with the descendants surviving.
(2) Same questions for the original cell or the original self-replicating molecule. (I know I've seen it asserted quite a few times that all cells or self-replicating molecules have a common original ancestor, though I can't recall a particular source that says it.) Duoduoduo (talk) 16:36, 15 October 2012 (UTC)[reply]
For question (1), the crucial thing is that chloroplasts, like mitochondria, contain their own DNA, separate from the DNA in the cell's nucleus. It is possible to compare chloroplast DNA for various plants and other photosynthesizing organisms to get an estimate of how long ago their evolutionary ancestry diverged.
For question (2), the main reason is that there are a number of complex metabolic mechanisms that are shared by all existing organisms. Our article on the evolutionary history of life gives references for that statement, if you are interested in more information. Looie496 (talk) 16:48, 15 October 2012 (UTC)[reply]
On point (1b), saying that all organisms of a given line (or all living organism) came from single events doesn't mean that the events were themselves the only instance of such an event before or since, just that the other lines from the other "events" have gone extinct. Just to use another example, Mitochondrial Eve wasn't the only Homo sapiens woman at the time she lived. She's just the one whose matrilineal line didn't eventually get subsumed by another (or die out) over the hundreds of thousands of years since then. --Mr.98 (talk) 16:50, 15 October 2012 (UTC)[reply]
Good answers above. I'll just note that (at a glance), the article does seem to contain a good overview/review of the related work that has constitutes this "accumulating evidence" of single-origin chloroplasts. The content may or may not be easily accessible, depending on your background. Drop me a line if you'd like me to send you the article. SemanticMantis (talk) 16:55, 15 October 2012 (UTC)[reply]
"Careful" science too often involves deliberate semantic gaming to be vague. "A single event" or "a cyanobacterium" might not refer to a single chloroplast. It is possible that a wide population of billions of symbiotic cyanobacteria was being taken up from the outside world by cells for a long time, then the cells gradually picked up genes from the cyanobacteria, which led to individual bacteria separately losing them under selective pressure, etc. The divergence of the individuals within a single population of a single species is far too small to show up against the larger mutational noise after all this time; so far as I can imagine (which is not proof...) there is no way to prove it was or was not a single individual chloroplast that produced the rest. Wnt (talk) 19:00, 15 October 2012 (UTC)[reply]
I don't think that's actually what they're saying. The two clades simply correspond to the most widely branched groups of plants. Wnt (talk) 23:56, 15 October 2012 (UTC)[reply]
This text
The paraphyly of Guillardia and Odontella, with respect to the two red algae, also suggests independent acquisition of secondary chloroplasts in the heterokont and cryptophyte, in contrast to the hypothesis of a single secondary endosymbiotic event among the chromophytes (Cavalier-Smith 2000). Although a single origin of the chloroplasts in this group is supported in some analyses (De Las Rivas, Lozano, and Ortiz 2002; Yoon et al. 2002), the topology of these four taxa in our tree is identical to that based on a recent, traditional analysis of protein-coding genes in the genomes (Martin et al. 2002). Analysis of small subunit ribosomal DNA in the chloroplasts from a wide variety of rhodophytes and chromophytes also indicates that chloroplasts of the latter group have independent origin
Well, secondary chloroplasts are surrounded by three or four membranes and are the remnants of a larger endosymbiont. I think all the varieties mentioned are in reference to the secondary events. [45] emphasizes that all, in the beginning, came from one event. Wnt (talk) 01:26, 16 October 2012 (UTC)[reply]
Yes, I am familiar with that concept from reading I did in the 90's, although I don't fully know how to interpret what I am reading here. It seems strange that secondary endosymbiosis would have more origins than primary. I would think the bottom line would be, is there a phylogeny that shows one type of chloroplast is more closely related to one type of bacteria, while a second type of chloroplast is more closely related to a second type of bacteria than it is to the first type of chloroplast. μηδείς (talk) 01:41, 16 October 2012 (UTC)[reply]
Here is something interesting: a few months ago, in vivo research has indicated that an endosymbiotic event is close to completion, the event would result in a new generation of plants which capable of nitrogen fixation. The event is creating a new plastid termed a nitroplast.
One cell (a prymnesiophyte), incapable of nitrogen fixation, is engulfing another cell (Candidatus Atelocyanobacterium thalassa) -- a cyanobacterium that can. That cyanobacterium will become the ancestor of every future nitroplast. Plasmic Physics (talk) 07:17, 17 October 2012 (UTC)[reply]
They stress that the particular species of prymnesiophyte may not be the only host cell involved in this event, it is just the only one encountered thus far. Plasmic Physics (talk) 07:23, 17 October 2012 (UTC)[reply]
Most Recent Common Ancestor - Pre-Columbus
I was perusing the article Most_recent_common_ancestor, and I was quite surprised to see it proposed that "With the advent of mathematical models and computer simulations, researchers now find that the MRCA of all humans lived remarkably recently, between 2,000 and 4,000 years ago." Of course, this is followed by a [citation needed] tag.
Assuming that this is the accepted time frame, the article states that this is attributable to the introduction of the genetic material of the European colonizers around the world. My question is, have pre-contact remains in the Americas or Australia been tested to determine how far back they would have shared a common ancestor with, say, the Spanish conquistadors?
I'm not expecting people to come to this conclusion, but I'm amusing myself about how it would certainly turn things upside down if it were discovered that Columbus and the poor Native American individuals he abducted and took to Spain as specimens were removed from the same ancestor by only 1500-3500 years. Falconusptc21:58, 15 October 2012 (UTC)[reply]
I've been wondering about this recently too. Does the claim that the MRCA lived at most 4,000 years ago imply that every now-living person (including Australian aboriginals, and members of 'uncontacted' South American and Indian Ocean tribes) is descended from someone who lived before even the earliest 'modern' transatlantic contact, but long after the rise in sea levels and corresponding vanishment of ice bridges that placed Alaska out of reach of Asia, and Australia out of reach of Southeast Asia? AlexTiefling (talk) 22:10, 15 October 2012 (UTC)[reply]
I'm hunting for a paper that even makes that claim, but it's clear to me it's not a universal opinion. This paper from earlier this year, looking at particular populations amongst Asians and Native Americans is sticking to the more common claim of ~15,000 years. They do speculate that populations often described as "isolated" for however-many years may have had occasional interlopers entering their community from later migrations, reducing the age of the MRCA. Anyway, still looking for a source for the 2-4kya claim, which does seem kind of ridiculous. It's going to be heavily dependent on what model they used to produce that number. Someguy1221 (talk) 22:40, 15 October 2012 (UTC)[reply]
PMID 15457259 may be what you are looking for. The basic idea is that everybody throughout the whole world has at least some recent European ancestry. There is certainly no claim that the Indians who Columbus met had recent common ancestry with him -- the claim is all of their descendants have picked up some European blood in the meantime. I have edited the MRCA article a bit to make it clearer that the statement in question was referring to the material in the following two paragraphs. Looie496 (talk) 23:32, 15 October 2012 (UTC)[reply]
I have removed the claim, it's absolute nonsense. The source is one author, duplicated by citing the same work in a preliminary form that explicitly says not for citation. One computer modeling program cannot override the clear evidence that there are pure aboriginal populations in the Americas and Australia with pedigrees at least 15,000 years separated from the old world, let alone Europe. μηδείς (talk) 23:50, 15 October 2012 (UTC)[reply]
The proper reference would be the one I cited above (PMID 15457259), which covers the same material and was published in Nature. Looie496 (talk) 00:28, 16 October 2012 (UTC)[reply]
I don't have a huge problem with citing the study if it is attributed to the authors and if the implication, that there are no surviving pure Amazonian or Australian aborigines is made explicit. But the study is basically a report about a computer model, not about reality, (i.e., if you write a program with such premises you get such results,) and I don't see it meriting any weight. μηδείς (talk) 00:59, 16 October 2012 (UTC)[reply]
I haven't read the article, but from the abstract, I agree with Medeis. It is only a "what if" computer experiment, useful only if you are trying to establish the validity of other similar computer models. --Lgriot (talk) 07:39, 16 October 2012 (UTC)[reply]
Well, I think that the modelling study (which I also have not read) could be indicative of the facts - I'll see if I can get a friend with PubMed access to get me a copy. But yes - we should avoid repeating its conclusions as though they are the facts on the ground. AlexTiefling (talk) 09:31, 16 October 2012 (UTC)[reply]
SomeGuy - isn't that paper talking about MRCAs specifically for mitogenetic elements? If I've understood correctly, that means we'd be looking at specifically matrilineal common ancestors, and those could easily be an order of magnitude more ancient than the general MRCA. But maybe I've misunderstood (again). AlexTiefling (talk) 09:41, 16 October 2012 (UTC)[reply]
You're absolutely correct, and it's something I should have mentioned, and yeah, it doesn't really touch on the general MRCA (it just provides an upper bound). It's worth noting that MRC-patrilineal-A and MRC-matrilineal-A are much more active research subjects than the basic MRCA as they are easier to handle (virtually no recombination for Y-chromosomes or mito-DNA). Someguy1221 (talk) 03:45, 17 October 2012 (UTC)[reply]
Alright, thanks all! I thought it was really interesting, but then if it really came out that the genetics were that mixed up, it would have made for more than a brief note on a Wiki Article. Falconusptc03:29, 17 October 2012 (UTC)[reply]
Well, let's suppose we start by imagining a possible MRCA living in the southern Urals around the time of the Trojan War (1100BCE). Let's suppose a moderate reproductive rate of 3 children per parent per generation surviving to reproduce. The 100-year rule implies that by the time of Julius Caesar, this person would have 30 generations' worth of descendants. If all of them were completely exogamous, that would be 3^30 = 200 trillion descendants. This is obviously absurd - but it's certainly credible for everyone in Eurasia, Africa and the surrounding islands at that date to be descended from our putative MRCA - mostly many times over. The same logic applies to the succeeding 1000 years - any one person alive at the time of Caesar could be an ancestor to the whole Old World by the time of Erik the Red. If just one of Erik's son Leif the Lucky's crew successfully reproduced with a 'skraeling' inhabitant of the New World just once, and that child survived to reproduce at the previously assumed rate, that child might have around 5 million descendants in the New World at the time of Columbus's arrival.
Meanwhile, on the other side of the world, the Macassans have been visiting northwestern Australia in their canoes for centuries. As they're based on the Asian mainland and adjacent islands, they're almost certainly all descended from our Uralic MRCA by now. Again, it only takes one of them to reproduce with one Australian Aboriginal person for a similar logic to apply to that entire population at the time of Europeans' first direct contact with them. So it's not unbelievable for the MRCA of all humanity to have been within 3000 years of Columbus at the time he set sail. I wouldn't want to guess, though, at the date of the universal MRCA at the time of Erik the Red. That might have been as long as 10,000 years previously. AlexTiefling (talk) 11:11, 17 October 2012 (UTC)[reply]
October 16
2 questions: Human powered flight and looking for the name of a theory
While watching the video in this article from NPR about the Sikorsky Prize for human powered flight, it made me wonder. Why would they build a system where the pilot has to use both his arms and legs? Wouldn't he be able to put more power into his legs if he could use his hands to brace himself? It seems to me that it would also be more fluid of a motion.
Also, it brings to mind a theory/principle/something that I read about here years ago. Basically it said that if you have a group of people pulling on a rope, the combined pull will have less force than if you were to add up their individual pulling forces when pulling one person at a time. Can anyone name what I'm thinking of? Our article used tug of war as an example but I can't find the term that I'm looking for when I look through what links to that article. Dismas|(talk)00:15, 16 October 2012 (UTC)[reply]
The reason is simple: By using both arms and legs, more muscles are brought into use, so greater power. For sustained effort, finite lung capacity comes into effect - evolution has provided us with lungs that are insufficient for maximum output from all muscles simultaneously, but for 60 seconds or so each muscle can run on oxygen held in the blood, and CO2 levels don't rise too much. Wickwack124.182.43.72 (talk) 01:13, 16 October 2012 (UTC)[reply]
I must admit I'm not a good swimmer, however I can swim. It seems to me that one's arms get to be used at something like full power, but while the legs contribute, they don't operate at maximum effort. Something that does use both, plus other muscles as well, at high effort is rowing in a racing skiff. I've never done that, but such races seem to be very short in duration. Wickwack 124.182.187.189 (talk) 14:56, 16 October 2012 (UTC)[reply]
The contribution of different muscle groups depends on style and speed. For freestyle, about 80% of the force comes from the arms. For sprints, legs are important, but for long-distance swimming, you mostly only use the legs to keep the body in a good horizontal position. Those big leg muscles eat up oxygen like there is no tomorrow... --Stephan Schulz (talk) 21:14, 16 October 2012 (UTC)[reply]
Extending the above question, wouldn't a plane that was neutrally buoyant (mostly filled with helium, or, if you dare, hydrogen), and covered with solar cells, in addition to being human powered, do better than one which is human powered alone ? (I realize this is likely against the rules of the competition.) StuRat (talk) 06:04, 16 October 2012 (UTC)[reply]
StuRat's idea has been proposed before, but it's not a good idea. It depends on what you define as better. Sure you can use helium or hydrogen to make a craft neutrally boyant in air, but the required volume means it will have a big surface area and will want to go where the wind takes it, so you'll need a bigger power input to make it go where you want. This is why you see conventional winged airplanes carrying freight, but not airships. The power to payload ratio of winged aircraft overtook airships many decades ago. Wickwack 124.182.187.189 (talk) 10:31, 16 October 2012 (UTC)[reply]
I realize this idea isn't practical as far as a commercial way to transport people or cargo. However, it might have recreational possibilities. That is, it might be a reasonable alternative to things like hang gliders, hot air balloons, and ultralights. And, just like those, you would be restricted to days with low wind, and, due to the use of solar panels, you'd also need bright sunlight. StuRat (talk) 02:17, 17 October 2012 (UTC)[reply]
Fair enough. But what we should do here is ask does combining gas buoyancy and power give us a synergistic advantage (or the best of two worlds) or does it just combine disadvantages? There's no doubt that hot air ballooning has considerable followers - I've tried it myself and its great fun, especially when you turn that great noisy burner off. Forget hydrogen - one bit of static discharge and your gone. Would helium catch on? Well, its pretty darn expensive - accepable for niche commercial purposes but too expensive for recreation. Now, does adding propulsion power to helium buoyancy give an advantage? Well yes it does, but once you have implemented propulsion power, regardless of the power source (gasoline engine, solar cells or whatever) you are better off with wings, as explained. That is, combine human power with solar power not in a buoyant lift craft but in a winged craft. But that's for chaps with olympic-standard fitness. What might have some synergistic recreational merit is a winged craft with solar cells covering the wings for cruising power, plus a small gasoline engine for take-off power. It should be possible as technology advances to get the weight of the solar cells and electric motor lower than the fuel weight for cruising range, and stay aloft for a long time that way. Wickwack 124.182.144.228 (talk) 02:46, 17 October 2012 (UTC)[reply]
A gasoline engine would add weight, fumes, and noise. They could jump off of hills like hang-gliders do, to get started. And yes, my idea was hydrogen or helium filled inflatable wings with flexible solar panels on top (hydrogen is only flammable when mixed with air). I believe an unmanned vehicle was made like this, and stayed aloft for many days. But, my version wouldn't have batteries for night storage of energy and would add a pilot who could hopefully control the flight direction with a leg/solar-powered, turnable fan. The price of helium is a concern, especially if it was all just vented to deflate the aircraft for storage. Is there a way it could be sucked out and recompressed back into the tanks ? StuRat (talk) 06:39, 17 October 2012 (UTC)[reply]
I'm sure there is, though it might cost some significant energy. The problem is that if you have neutral buoyancy at some altitude, to descend you must either vent some helium (the usual way back in the 1930's), or compress it on board, which has been proposed before. The power to weight ratio of constant-speed gasoline engines is excellent, however maybe you should calculate how much cranking a human would need to do to control altitude by manual onboard gas compression. Don't be too concerned about the noise of an IC engine - you should hear the noise of a hot air ballon gas burner in full cry just above your head. My usual statement for this type of discussion on Ref Desk applies: Should a hand compressed helium lift wing work out, with or without photo-voltaic boosting, don't bother patenting it, folks, as by posting all these response StuRat & I have established prior art. Wickwack 124.178.143.72 (talk) 08:38, 17 October 2012 (UTC)[reply]
Perhaps make the vehicle slightly heavier than air, so that modest pedaling or sunlight on the solar panels provides sufficient thrust to provide the extra lift needed, via the airfoil. StuRat (talk) 08:52, 17 October 2012 (UTC)[reply]
Re hydrogen only flammable when mised with air (or oxygen) - yes, that's obviously true. Trouble is, it is the leakiest stuff imaginable, that tiny molecule can permeate such a range of things. Its pretty hard to guarantee it doesn't get mixed with air somewhere, it is combustible down to very low concentrations, and ignitable by the tiniest static discharge spark. Best avoided. Wickwack 124.178.143.72 (talk) 08:38, 17 October 2012 (UTC)[reply]
Well, there is some risk, but I do feel the risk has been overstated as the result of the Hindenburg disaster (where the source of ignition was likely a flammable surface treatment). After all, most aircraft contain flammable fuels, it's just a matter of properly containing them to prevent explosions. Isn't there any flexible material which is impermeable to hydrogen ? StuRat (talk) 08:52, 17 October 2012 (UTC)[reply]
As the WP article covers quite well, many and various are the theories why the Hindenburg burned, and we cannot really know, but the official and most likely cause is a static electricity discharge. While aircraft fuel (gasoline or kerosene) is regarded as highly inflamable, there is a very considerable difference between these fuels and hydrogen. For a start, aircraft fuels being hydrocarbon liquids, they must first be vaporised and pyrolised (ie the molecules split up) before combustion can occur. Once vaporised they can all be ignited by a spark, but the required spark energy is very high in comparison. To ignite gasoline you need a clearly visible spark at least about 1 mm from any (cold) surface; for hydrogen you need only a spark too way too weak to be seen, and it can be right up against a surface. It's true that the extensive media coverage at the time including the live voice coverage turned the public off airships. But that doesn't change the fact that hydrogen filled airships, certainly of that design, were dangerous. Wickwack 124.178.143.72 (talk) 10:57, 17 October 2012 (UTC)[reply]
Will canned food become hard to taste before the rust level becomes harmful?
Though if you eat it without the liquid the majority of the rust taste disappears. Hey I'm poor, I'm gonna eat it if up to 60% of the flavor is rust. Otherwise I throw away a dollar. Of course it also matters how often you eat from rusty cans and how many a lifetime. Why do most of them not taste like rust but a few taste bad? And I can't imagine how crappy the unlucky ones taste like by the time they're the "best by" age, which are like 12 times older than the ones in the supermarket). 96.246.59.161 (talk) 05:03, 16 October 2012 (UTC)[reply]
I assume that English is a second language for you, and you meant to ask "Will I be able to taste that canned food is off before it becomes harmful, due to age ?". Most of the time, yes, but occasionally it might develop something nasty with no bad taste. I also don't think it's typically rust that you taste, it's more the coatings on the inside of the can and the oxidation of the contents. StuRat (talk) 05:53, 16 October 2012 (UTC)[reply]
I suspect this is getting a bit close to medical advice. FWIW from experience as a student it always seems that acid tinned stuff (grapefruit segments, tomatos) does get rusty. But although people have eaten rusty stuff no one is going to advise you its ok. The main ingredient of rust is Iron(III) oxide which is insoluble and not going to do much and if the manufacturers of the tin had you in mind there might not be seriously bad stuff. --BozMotalk05:55, 16 October 2012 (UTC)[reply]
It's worth remembering that as StuRat hinted at, the rust may not be your biggest concern with the tins. It's whatever has happened to the food due to whatever is growing on it thanks to the rusting/compromised tins. Nil Einne (talk) 11:49, 16 October 2012 (UTC)[reply]
Cans are always lined, and they don't rust on the inside. If they are damaged enough to expose the interior to rust, that's a very dangerous situation -- but it hardly ever happens. Most cans nowadays won't rust at all, unless exposed to something corrosive. The OP here is just making stuff up. Looie496 (talk) 14:57, 16 October 2012 (UTC)[reply]
Sure but if you can actually taste the rust as alleged by the OP or are going to be eating rust because of a rusting can as discussed by BozMo, then the dangers of the rust should not be high on your list of concerns. Nil Einne (talk) 15:02, 16 October 2012 (UTC)[reply]
What's in the coating that you taste it? Tin? It doesn't stop the 1.5 mm wide seam from rusting. Clearly if the can is damaged or has enough rust to eat it should be thrown out but I never saw one like that. 96.246.59.161 (talk) 23:22, 16 October 2012 (UTC)[reply]
Not sure what the metallic taste is. I've taken a bite from inside a can before, only to spit it right out due to a metallic taste, then check the expiration date and wonder if the can came with bell bottom pants and a rainbow colored disco wig. :-) StuRat (talk) 02:10, 17 October 2012 (UTC)[reply]
Why don't protons repel each other ?
As we know, protons are positively charged particles and it is also known that like charges repel each other. But protons occur in nucleus and they don't seem to repel each other. Why it is so ? What make protons and neutrons stick to each other ? Sunny Singh (DAV) (talk) 10:41, 16 October 2012 (UTC)[reply]
(ec) Protons do repel each other by electromagnetic forces, but at the same time, the Nuclear forces hold the protons and neutrons together. These nuclear forces work only at very small distances. Even then, neutrons are necessary to stabilize the nucleus because these contribute to the binding by means of nuclear forces, but they are electrically neutral do they do not repel each other or protons. - Lindert (talk) 10:57, 16 October 2012 (UTC)[reply]
Actually neutrons stabilize the nucleus by reducing its Fermi energy - that's why stable nuclei have about as many protons as they have neutrons. Only for large nuclei does the electric energy becomes somewhat important - that's why heavier nuclei have an excess of neutrons (compared to their number of protons). Dauto (talk) 14:02, 16 October 2012 (UTC)[reply]
You can imagine the nucleus (especially heavy nuclei) as a balance of contradictory forces. When it gets out of balance, little bits can shoot out (radioactive decay) or, in extreme cases, the whole thing can rupture into two pieces (nuclear fission). Understanding that protons do repel each other, except at very small distances, also helps make sense of why nuclear fusion is so hard — you have to get the protons close enough to each other for the nuclear force to win out over the electromagnetic force (the Coulomb barrier — illustrated here). --Mr.98 (talk) 14:54, 16 October 2012 (UTC)[reply]
If someone give further explanation of my first question, I'll thankful to him.
We know that protons and neutrons are made up of up and down quarks. I want to know which particles constitute electrons ? Sunny Singh (DAV) (talk) 02:00, 17 October 2012 (UTC)[reply]
What is unclear to you about the examples already given to you to the first question? The basic answer (the nuclear force) is discussed above, along with some more complicated refinements (e.g. Fermi energy). Protons do repel one another because of the electromagnetic force, but at short distances the nuclear force is dominant, which causes nucleons to attract to one another. The linked-to articles above go into nearly endless technical details. Just let us know what is unclear and someone will happily elaborate or translate into laymen's terms. --Mr.98 (talk) 02:45, 17 October 2012 (UTC)[reply]
Considering a bath of ice at -10°C to which NaCl salt is added on surface, hence forming a layer of eutectic ice NaCl•H2O (melting at -22°C instead of 0°C), the Gibbs free energy of the melting eutectic ice in a 25°C thermostated-environment will roughly have the following form:
Experimentally, the use of a thermometer will show that the salted ice goes to -22°C when melting, hence showing that the first term of the equation (integral from -10°C to -22°C) describes the first physically occuring response of the system when heated to 25°C. This integral being the only negative term of the equation (entropy aside), my question is: which energy is transferred to the environment during the -10°C → -22°C transition? Would it be a heat transfer? Thanks, 188.194.48.183 (talk) 11:10, 16 October 2012 (UTC)[reply]
The temperature drop that occurs when the salt is added to the water comes from the net endothermic solvation process. The breaking of the Na-Cl ionic bonds is more endothermic than the formation of the solvent-ion bonds is, so it's just an endothermic heat of solution. That's why the temperature of the solution drops: the energy is being used to cause the NaCl to dissolve. --Jayron3221:44, 16 October 2012 (UTC)[reply]
Likely heat situation of the ~26-mile BASE jumper yesterday
Regarding the man who went up in a helium balloon and jumped from what I'm hearing is about 26 miles altitude and reaching about 834 mph, I saw in a brief shot on the news that he was wearing a sort of space suit that seemed to be made of flexible fabric material. I wonder, given the composition of the atmosphere at the point at which he was going 834 mph, what was the likely temperature (ballpark figure) due to friction? 20.137.2.50 (talk) 13:37, 16 October 2012 (UTC)[reply]
That's a good question. The suit Felix Baumgartner was wearing was a heated pressure suit, intended to keep him at a comfortable air pressure, and nice and warm, in the near vacuum of such high altitudes. That 834 mph was possible because, at that time, he was falling through so little air that there was little friction acting on him. The terminal velocity at low altitude is about 120 mph. So Baumgartner will have slowed from 800 to maybe 100 mph before he deployed his parachute. That speed will all have been lost due to friction (most in the last minute or so). Handwavingly assuming Baumgartner, suit, chute, et al weighed in at 200kg, I figure his kinetic energy was 12.7 MJ at the fastest point, down to about 0.2 MJ when he was at ~100 mph - meaning he'd have lost 12.5 MJ of kinetic energy. Not knowing much about the aerodynamics of falling spacesuits, I don't know how much of that went to eating up the air, and how much to heating up the suit. -- Finlay McWalterჷTalk14:08, 16 October 2012 (UTC)[reply]
Hopefully most of that energy heated up the air! I estimated a little bit differently, assuming that all the gravitational potential energy needs to convert to heat (well, most of it, anyway); so I got about 35 MJ using the standard "PE = mgh" formula. To order of magnitude, it's the same as Finlay's estimate. And, assuming a human is mostly water, with a specific heat capacity of 4.18 J/g·K, that's enough energy to raise a 90 kg human by almost 100 degrees centigrade! That's probably fatal! Of course, the rate that heat is conducted and radiated to the surrounding air is very rapid; and a human in a space suit is not well-approximated by an equal mass of water; but to first order, we have to assume that the majority of that thermal energy is lost to air and/or ablation of the suit - hopefully in an engineered fashion. Nimur (talk) 15:56, 16 October 2012 (UTC)[reply]
[46] says that a failure of the heater in his face plate was not an issue in the capsule but would be on jumping. This confirms your impression that the rapid cooling effect from the passing -60 degree air is overwhelming the heat from reentry. Reentry from space involves much more lost potential energy and much less cooling by contact... in any case, I think your estimate and answer puts us in the lead! :) Wnt (talk) 17:06, 16 October 2012 (UTC)[reply]
I am sure there was some heating effect but I doubt it was a large one. 800 mph is fast, but is still very much less than the speeds of spacecraft re-entering the atmosphere from low Earth orbit - about 16,000 mph - or the speeds at which meteorites enter the upper atmosphere - at least 25,000 mph. Gandalf61 (talk) 14:55, 16 October 2012 (UTC)[reply]
When he was going 800 mph, that was the "local" terminal velocity, which gradually became less as the atmosphere became more dense. So, when he was going 800 mph, the air resistance was equal to his weight, therefore the dissipated power at that time and later was his weight times his velocity and that was maximal right at that time when he reached maximal velocity. So, if he weighs 80 kg, the maximal dissipated power he experienced would be about 290 KW. This is way more than he could have sustained on the long run, but then this only lasted for a matter of seconds.
Another way to see that 800 mph is a problem, is to compare the velocity at which the air molecules hit you at that velocity with the how fast they hit you at rest and compute how high the temperature needs to be for this to be the same. You can roughly estimate this as follows. At rest at -40°C, <v^2> is about (455 m/s)^2 )(using the formula 3 k T/m), the component in the direction of motion is a third of this, so sqrt[<vz^2>] = 263 m/s. If we add to this the 800 mph, we get vz = 623 m/s, so relative to Baumgartner,
sqrt[<v^2>] = (sqrt[623 m/s)^2 + 2 * (263 m/s )^2] = 725 m/s.
This is the same as being at rest at a temperature of 317 °C. In reality it isn't the same, because the frequency of the collision is less at lower densities. Count Iblis (talk) 17:09, 16 October 2012 (UTC)[reply]
Additional complexity arises because these speeds are in the transsonic and supersonic regime; in other words, an air molecule traveling at 725 m/s at stratospheric densities is not in kinetic equilibrium. Each molecule is, in fact, in shock. I don't believe you can apply conventional gas temperature calculated from velocity according to the equipartition theorem, in this regime. Our article has information on attached shock, for molecules impacting the falling person; and detached shock, for the aerodynamic phenomenon that will inevitably form. Aerothermal heating in the transsonic and supersonic regime is widely studied. For the very enthusiastic thermodynamicist, NASA makes available an excellent free text, Facing the Heat Barrier: A History of Hypersonics - about the physics at much faster than super-sonic speeds. Aerodynamics of "hypersonic" flight are defined by the gas regime when thermal effects are more important than any other physical aerodynamic effect. This is usually around Mach 5 or higher. This is one reason that spacecraft reentry systems use reaction control systems, and not flaps or parachutes - because conventional aerodynamic control surfaces do not behave as expected at these speeds. This book mostly applies to hypersonic aircraft; but I also found the more conventional book, Entry heating and thermal protection, which seems to provide a lot more practical approach, covering material more applicable to jumping out of a balloon at 120,000 feet. Nimur (talk) 19:38, 16 October 2012 (UTC)[reply]
Let's expand this a little. 80 kg * 9.8 m/s^2 = 784 newtons (kg m/s^2) of weight. The negative work (energy released) done by this weight is force x distance = 784 kg joules (m^2/s^2) per meter fallen. We know he falls 0.447(m/s/(mi/hr) conversion factor)*(800 mile/hour) = 357 m/s, so the energy released is his weight 784 kg m/s^2 * his velocity (357 m/s) = 280000 kg m^2/s^3 = 280000 watts. If I didn't foul up, that's a lot of power - at least twice what an automobile engine produces, according to the article. But for each second of this power output he passes through 357 meters of the surrounding air, releasing the original 784 joules per meter. So the question is, how much of a temperature differential will it require to get the surrounding air to take up 784 joules as it rushes past? Hmmm.... Wnt (talk) 18:02, 16 October 2012 (UTC)[reply]
Too bad they couldn't have fit one more thing, a temperature sensor, into his chest pack, if only for my personal curiosity's sake :). An ounce of actual measurement is worth a ton of theory. But from the mission's own site regarding his pressure suit: "The suit is designed to provide protection from temperatures of +100°F to -90°F." I guess there's my ballpark figure from the people closest to the real and true answer 20.137.2.50 (talk) 20:50, 16 October 2012 (UTC)[reply]
So, from above, we have that he must be dumping 0.2 MW into the air at his peak velocity. Assuming an air density of 0.03 kg/m^3 at that height and an effective cross-section of say 0.8 m^2, that implies about 9 kg / s of perturbed air. With a specific heat of around 1 J / gram / K, that ballparks the heating of the air at around 25 Kelvin. So, it would seem that his problem is likely to be cooling due to low ambient temperatures rather than overheating due to friction, at least during the fastest part of his trip. Dragons flight (talk) 00:52, 17 October 2012 (UTC)[reply]
October 17
Chemistry to dissolve human poo?
What does human poo consist of? fats? protein? is it polar or non polar? and more importantly what is the chemistry that will dissolve it? just like alcohol dissolve oil etc. Electron9 (talk) 02:24, 17 October 2012 (UTC)[reply]
Seems to normally be low on fats, so will just dissolve in water with a bit of agitation. However, some people with non-functional gall bladders or using diet products like Orlistat do pass substantial portions of fat, so adding some detergent would cover those cases. StuRat (talk) 02:38, 17 October 2012 (UTC)[reply]
Ah yes, and there's always the corn kernels to deal with, along with seeds and perhaps grains of sand, which aren't going to dissolve in anything short of a powerful acid or base. StuRat (talk) 06:30, 17 October 2012 (UTC)[reply]
Mystery leaf 'streamers'
Maple leaf with 'streamers'
I took the photograph at right this weekend in central Ontario, Canada, about 100 km north of Toronto. It was on a small maple tree, on which a number of leaves had these dark, vertical 'streamers' (about 1 cm long) sticking out of their upper surfaces. Some leaves had just a few, others (like the one pictured) were heavily covered.
That's pretty neat, the mites are able to alter the leaf cells to grow a gall around them. Tiny genetic engineers at work. StuRat (talk) 06:27, 17 October 2012 (UTC)[reply]
Gas engine or gasoline engine, taking it that it is in any case a spark ignition piston engine: In vintage engines, a temporary increase in oil consumption above normal tended to occur as carbon at the top of the piston formed a seal - the carbon got removed in overhaul and needs to build up again. However in modern engines, especially for bowl-in-piston/squish land piston/EE-type combustion chambers, a noticeable increase (as distinct from a modest increase) in oil consumption is a sign of errors in rebuilding. Posible errors are: cylinders not correctly honed, incorrect oversize piston and/or rings fitted wrt cylinder re-bore, piston rings incorrect or incorectly fitted, problems with valve guides. A possible problem is the oil presure control spring together with tight bearings causing higher oil pressure leading to over lubrication of valve gear. At one time, new engines and overhauled engines were initially filled with "running-in" low-viscosity oil, which also increases consumption, but this should not be done nowadays. Wickwack 124.178.143.72 (talk) 08:17, 17 October 2012 (UTC)[reply]
New exoplanet temperature
See [47]. That says the surface temperature is around 2200°F, due to it's proximity to the star. However, at that distance it's sure to be tidally locked to it's star (unless the planet is very young). If we also assume it to have no atmosphere or liquid covering it (having been blown off by the solar wind), wouldn't the dark side be far cooler ? StuRat (talk) 09:03, 17 October 2012 (UTC)[reply]
I was reading the wikipedia perverted justice article and Im confused as to how they convicted these people if the decoy was actually over 18? It even says in the article
"The father of a man arrested in a July 2006 sting by Perverted-Justice has appeared before a Georgia Superior Court judge to seek an arrest warrant for Von Erck, alleging that Von Erck solicited the commission of a felony from the man.[77][78] The judge found that probable cause existed to believe Von Erck impersonated a girl and solicited the man with the intent for him to commit a felony, but declined to issue the warrant because when the act occurred, there was no actual girl and thus no crime occurred.[77] The act of soliciting a felony is itself a felony.[78] Attorney Gary Gerrard filed an appeal with the Georgia Court of Appeals, alleging that under Georgia law, solicitation is a felony whether or not a crime occurred.[79] That appeal was ultimately rejected.[80]"
The law is often explicitly written so that such stings can result in convictions. It sounds like that wasn't the case in Georgia, but it may well be the case in other states. There may be a specific offence of attempting to sollicit that says it is the age the offender thinks the person is rather than their actual age. Or it may just be a matter of how attempted offences are defined in that jurisdiction. --Tango (talk) 11:32, 17 October 2012 (UTC)[reply]
does a nurse need to expel air from a prefilled flu vaccine
Resolved
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