Environment variable

Environment variables are a set of dynamic named values that can affect the way running processes will behave on a computer.

They are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store temporary files, or the HOME or USERPROFILE variable to find the directory structure owned by the user running the process.

They were introduced in their modern form in 1979 with Version 7 Unix, so are included in all Unix operating system flavors and variants from that point onward including Linux and OS X. From PC DOS 2.0 in 1982, all succeeding Microsoft operating systems including Microsoft Windows, and OS/2 also have included them as a feature, although with somewhat different syntax, usage and standard variable names.

Details

In all Unix and Unix-like systems, each process has its own separate set of environment variables. By default, when a process is created, it inherits a duplicate environment of its parent process, except for explicit changes made by the parent when it creates the child. At the API level, these changes must be done between running fork and exec. Alternatively, from command shells such as bash, a user can change environment variables for a particular command invocation by indirectly invoking it via env or using the ENVIRONMENT_VARIABLE=VALUE <command> notation. All Unix operating system flavors, DOS, and Windows have environment variables; however, they do not all use the same variable names. A running program can access the values of environment variables for configuration purposes.

Randomness

Randomness is the lack of pattern or predictability in events. A random sequence of events, symbols or steps has no order and does not follow an intelligible pattern or combination. Individual random events are by definition unpredictable, but in many cases the frequency of different outcomes over a large number of events (or "trials") is predictable. For example, when throwing two dice, the outcome of any particular roll is unpredictable, but a sum of 7 will occur twice as often as 4. In this view, randomness is a measure of uncertainty of an outcome, rather than haphazardness, and applies to concepts of chance, probability, and information entropy.

The fields of mathematics, probability, and statistics use formal definitions of randomness. In statistics, a random variable is an assignment of a numerical value to each possible outcome of an event space. This association facilitates the identification and the calculation of probabilities of the events. Random variables can appear in random sequences. A random process is a sequence of random variables whose outcomes do not follow a deterministic pattern, but follow an evolution described by probability distributions. These and other constructs are extremely useful in probability theory and the various applications of randomness.

Random (Lady Sovereign song)

"Random" is the first CD single from UK hip hop artist Lady Sovereign, following the release of her 12" vinyl single "Ch Ching (Cheque 1 2)" in 2004. It was her second and last single for Casual Records in 2005.

The single was Lady Sovereign's first to make the UK top 75, peaking at #73 there and spending one week within the top 75. After the single release, she was signed by Def Jam Recordings and this single is considered to be her breakthrough into the mainstream market.

"Random" was featured on an episode of The O.C. aired on April 27, 2006, playing in the background during the senior prom in Season 3, Episode 23 - "The Party Favor" and was featured as a track on Midnight Club 3: DUB Edition Remix. A remix of this song was played on the "Jamalot" episode of CSI: NY.

The first rapped line in the song references the hit song "Tipsy" by J-Kwon.

Track listing

The Remixes - 12" Promo single

Radioactive decay

Radioactive decay, also known as nuclear decay or radioactivity, is the process by which a nucleus of an unstable atom loses energy by emitting radiation. A material that spontaneously emits such radiation — which includes alpha particles, beta particles, gamma rays and conversion electrons — is considered radioactive.

Radioactive decay is a stochastic (i.e. random) process at the level of single atoms, in that, according to quantum theory, it is impossible to predict when a particular atom will decay. The chance that a given atom will decay never changes, that is, it does not matter how long the atom has existed. For a large collection of atoms however, the decay rate for that collection can be calculated from their measured decay constants or half-lives. This is the basis of radiometric dating. The half-lives of radioactive atoms have no known limits for shortness or length of duration, and range over 55 orders of magnitude in time.

There are many different types of radioactive decay (see table below). A decay, or loss of energy from the nucleus, results when an atom with one type of nucleus, called the parent radionuclide (or parent radioisotope), transforms into an atom with a nucleus in a different state, or with a nucleus containing a different number of protons and neutrons. The product is called the daughter nuclide. In some decays, the parent and the daughter nuclides are different chemical elements, and thus the decay process results in the creation of an atom of a different element. This is known as a nuclear transmutation.

Radio:Active

Radio:Active (stylised as Radio:ACTIVE) is the fourth studio album by English pop punk band McFly. It is the band's first album under their new, self-created label, Super Records. The album was first released via a promotion with the Mail on Sunday on 20 July 2008. The album was officially released on 22 September 2008, with the official release being branded the 'Deluxe Edition'.

Since its release, Radio:Active has sold over 500,000 copies worldwide. It also received a Silver sales status certification for sales of over 60,000 copies in the UK.

Background

McFly made the decision to first issue the album free with the Mail on Sunday. More than 2.4 million copies of the album were given away free, which represented a 300,000 copy increase from the paper's average circulation.Tom Fletcher revealed the strategy: "We get to put it into almost three million homes, which is an incredible opportunity for us. Hopefully the three million people will all enjoy the music and they'll decide to see us when we go on tour." Mail on Sunday managing director Stephen Miron said both "the band and the paper were very happy with the sale". The album was officially released in shops on 22 September 2008. Compared to The Mail on Sunday version, this version contained four extra tracks, but removes the single "The Heart Never Lies". This edition also includes a bonus DVD and a 32-page booklet.

Radioactive (Imagine Dragons song)

"Radioactive" is a song recorded by American rock band Imagine Dragons for their major-label debut EP Continued Silence and later on their debut studio album, Night Visions (2012), as the opening track. "Radioactive" was first sent to modern rock radio on October 29, 2012, and released to contemporary radio on April 9, 2013. Musically, "Radioactive" is an electronic rock song with elements of alternative rock and contains cryptic lyrics about apocalyptic and revolutionist themes.

The song received acclaim from critics, who praised the production, lyrics, and vocals, calling it a highlight on the album. Due to heavy rotation on various commercials and trailers, the song became a sleeper hit, peaking at number three on the US Billboard Hot 100 chart and becoming the band's first top 10 single as well as being the third best selling song in that country. It also broke the record for slowest ascension to the top 5 in chart history and currently holds the record for most weeks spent on the Billboard Hot 100 at 87 weeks. The song has also reached number one in Sweden and in the top 20 in several countries including Australia, Canada, New Zealand and the United Kingdom, becoming Imagine Dragons' most successful single to date. It has since been certified ten times platinum in the USA, making it the best selling rock song of all time and, regardless of genre, one of the best selling singles of all time.