Diffusion

Diffusion is the net movement of molecules or atoms from a region of high concentration (or high chemical potential) to a region of low concentration (or low chemical potential). This is also referred to as the movement of a substance down a concentration gradient. A gradient is the change in the value of a quantity (e.g., concentration, pressure, temperature) with the change in another variable (usually distance). For example, a change in concentration over a distance is called a concentration gradient, a change in pressure over a distance is called a pressure gradient, and a change in temperature over a distance is a called a temperature gradient.

The word diffusion is derived from the Latin word, "diffundere", which means "to spread out" (if a substance is “spreading out”, it is moving from an area of high concentration to an area of low concentration). A distinguishing feature of diffusion is that it results in mixing or mass transport, without requiring bulk motion (bulk flow). Thus, diffusion should not be confused with convection, or advection, which are other transport phenomena that utilize bulk motion to move particles from one place to another.

Molecular diffusion

Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles. Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration. Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules. The result of diffusion is a gradual mixing of material such that the distribution of molecules is uniform. Since the molecules are still in motion, but an equilibrium has been established, the end result of molecular diffusion is called a "dynamic equilibrium". In a phase with uniform temperature, absent external net forces acting on the particles, the diffusion process will eventually result in complete mixing.

Lexical diffusion

In historical linguistics, lexical diffusion is both a phenomenon and a theory. The phenomenon is that by which a phoneme is modified in a subset of the lexicon, and spreads gradually to other lexical items. For example, in English, /uː/ has changed to /ʊ/ in good and hood but not in food; some dialects have it in hoof and/or roof but others do not; in flood and blood it happened early enough that the words were affected by the change of /ʊ/ to /ʌ/, which is now no longer productive.

The related theory, proposed by William Wang in 1969, is that all sound changes originate in a single word or a small group of words and then spread to other words with a similar phonological make-up, but may not spread to all words in which they potentially could apply. The theory of lexical diffusion stands in contrast to the Neogrammarian hypothesis that a given sound change applies simultaneously to all words in which its context is found.

Mainstream historical linguists reject Wang's hypothesis, continuing to adhere to Neogrammarian exceptionlessness. For example, Pulleyblank regards the theoretical formulation of lexical diffusion as presented by Hsieh in Wang 1977 as “so manifestly at odds with any realistic picture of how dialects are inter-related and how innovations spread spatially through a language as to make them totally untenable” (1982: 408).

Fracture

A fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface of displacement, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially to the surface of displacement, it is called a shear crack, slip band, or dislocation.Fracture strength or breaking strength is the stress when a specimen fails or fractures.

The word fracture is often applied to bones of living creatures (that is, a bone fracture), or to crystals or crystalline materials, such as gemstones or metal. Sometimes, in crystalline materials, individual crystals fracture without the body actually separating into two or more pieces. Depending on the substance which is fractured, a fracture reduces strength (most substances) or inhibits transmission of light (optical crystals). A detailed understanding of how fracture occurs in materials may be assisted by the study of fracture mechanics.

Fracture (company)

Fracture is an Internet-based photo finishing service. Fracture's main service is printing photos directly onto glass. The company is based in Gainesville, Florida.

History

A startup company in North Central Florida, Fracture was founded by two graduates of The University of Florida, Alex Theodore and Abhi Lokesh. They began selling their product in December 2009. Theodore and Lokesh raised $1.5 million in funding from outside investors, including Tamiami Angel Fund I in 2012.

In 2011, after a Groupon promotion, sales increased significantly, and the company moved to a larger building and had ten employees. In 2013 the company raised an additional $500,000 to pay for further expansion.

By 2014, the company had filled about 50,000 orders.

Features

Customers upload photos through the company's website and get back those photos printed on a pane of shatter-proof glass. The process takes about 48 hours, and the photos can be as small as 5x7 or as big as the custom 32x40 job.

Fracture (album)

Fracture is the second studio album by Leeds Jazz-Rock ensemble Roller Trio following the success of their Mercury Prize nominated debut album Roller Trio. It was released in 2014 and in The Guardian John Fordham said [Roller Trio] "have come up with a second album that’s different and diverse, and on a live show it must be a gas". London Jazz News said "This is a marker laid down by a group operating at the vanguard of contemporary jazz." The album received 4 stars in All About Jazz where the reviewer Phil Barnes said "This ability to blend the accessible and the serious, the melodic and the experimental is a real gift".

Track listing

Personnel

References

External links