City

A city is a large and permanent human settlement. Although there is no agreement on how a city is distinguished from a town in general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.

Cities generally have complex systems for sanitation, utilities, land usage, housing, and transportation. The concentration of development greatly facilitates interaction between people and businesses, benefiting both parties in the process, but it also presents challenges to managing urban growth.

A big city or metropolis usually has associated suburbs and exurbs. Such cities are usually associated with metropolitan areas and urban areas, creating numerous business commuters traveling to urban centers for employment. Once a city expands far enough to reach another city, this region can be deemed a conurbation or megalopolis. In terms of population, the largest city proper is Shanghai, while the fastest-growing is Dubai.

Origins

There is not enough evidence to assert what conditions gave rise to the first cities. Some theorists have speculated on what they consider suitable pre-conditions and basic mechanisms that might have been important driving forces.

City government in Washington (state)

There are 281 municipalities in the U.S. state of Washington. State law determines the various powers its municipalities have.

City classes

Legally, a city in Washington can be described primarily by its class. There are five classes of cities in Washington:

First class cities are cities with a population over 10,000 at the time of reorganization and operating under a home rule charter. They are permitted to perform any function specifically granted them by Title 35 RCW (Revised Code of Washington). Among them are Seattle, Tacoma, Spokane, Vancouver, and Yakima.

Second class cities are cities with a population over 1,500 at the time of reorganization and operating without a home rule charter. Like first class cities, they are permitted to perform any function specifically granted them by Title 35 RCW. Among them are Port Orchard, Wapato, and Colville.

Towns are municipalities with a population of under 1,500 at the time of reorganization. Towns are not authorized to operate under a charter. Like the previously listed cities, they are permitted to perform any function specifically granted them by Title 35 RCW. Among them are Steilacoom, Friday Harbor, Eatonville, and Waterville. In 1994, the legislature made 1,500 the minimum population required to incorporate.

Administrative divisions of Texas

Texas has a total of 254 counties, many cities, and numerous special districts, the most common of which is the independent school district.

County

Texas has a total of 254 counties, by far the largest number of counties of any state.

Each county is run by a five-member Commissioners' Court consisting of four commissioners elected from single-member districts (called commissioner precincts) and a county judge elected at-large. The county judge does not have authority to veto a decision of the commissioners court; the judge votes along with the commissioners (being the tie-breaker in close calls). In smaller counties, the county judge actually does perform judicial duties, but in larger counties the judge's role is limited to serving on the commissioners court and certifying elections. Certain officials, such as the sheriff and tax collector, are elected separately by the voters, but the commissioners court determines their office budgets, and sets overall county policy. All county elections are partisan, and commissioner precincts are redistricted after each ten year Census both to equalize the voting power in each and in consideration of the political party preferences of the voters in each.

Pinch (plasma physics)

A pinch is the compression of an electrically conducting filament by magnetic forces. The conductor is usually a plasma, but could also be a solid or liquid metal. Pinches were the first device used by mankind for controlled nuclear fusion.

The phenomenon may also be referred to as a Bennett pinch (after Willard Harrison Bennett), electromagnetic pinch,magnetic pinch,pinch effect or plasma pinch.

Pinches occur naturally in electrical discharges such as lightning bolts, the aurora,current sheets, and solar flares.

Basic mechanism

Types

Pinches exist in laboratories and in nature. Pinches differ in their geometry and operating forces. These include:

Common behavior

Pinches may become unstable. They radiate energy as light across the whole electromagnetic spectrum including radio waves, x-rays,gamma rays,synchrotron radiation, and visible light. They also produce neutrons, as a product of fusion.

Applications and devices

Pinches are used to generate X-rays and the intense magnetic fields generated are used in electromagnetic forming of metals. They also have applications in particle beams including particle beam weapons, astrophysics studies and it has been proposed to use them in space propulsion. A number of large pinch machines have been built to study fusion power; here are several: