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).

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BT Inspiration

The BT Inspiration is a PBX telephone switchboard made by Lake Communications of Ireland. It is also sold in Scandinavia and France under the name Doro ip500pbxw and is very similar to Pathway. The systemphones for Inspiration and Pathway look identical but they are not interchangeable.

The British Telecom Inspiration is flexible as it can also be used with standard telephones. However the more dedicated Featurephones you use, the easier it becomes to operate your system. One freedomphone on extension 20 is a minimum. The system features expansion up to 8 lines and 16 extensions, analogue or ISDN or a mixture of both; it supports Desktop ISDN and features like Call Transfer/Divert etc. and optional modules e.g. voicemail, door intercom, call manager and battery backup.

Optional menu driven Featurephone provides voicemail monitoring, directory access and is headset compatible. Supports standard analogue telephones. Freedomphone default password is 1111.

This switchboard is no longer sold by BT who now use BT Versatility.

List of Marvel Comics characters: P

Carolyn Parmenter

Carolyn Parmenter is a fictional character in the Marvel Universe. She was created by John Byrne, and first appeared in Incredible Hulk #317 (Mar. 1986).

Carolyn Parmenter was a member of Bruce Banner's Hulkbusters, a team of highly skilled individuals selected to capture and study the Hulk. Carolyn was a marine scientist trained in the fields of biology, oceanics, scuba diving, and exploration.

Carolyn was the girlfriend of fellow Hulkbuster, Samuel LaRoquette. Carolyn was killed during a battle with Doc Samson.

Papa Jambo

Papa Jambo (Charles LeJeune), is a fictional character in the Marvel Universe. Papa Jambo was a very proficient and well-trained Voodoo Houngan from Haiti, skilled in magic who trained both Daniel Drumm and Jericho Drumm (Brother Voodoo and much later known as Doctor Voodoo; the Sorcerer Supreme). Jambo died after passing on his many years of knowledge onto Brother Voodoo, his successor to combat and defeat Damballah, a pawn of the Serpent God, Set, who came to Port-au-Prince to take control of the local communities.