Tuesday, July 31, 2007


A market is a social arrangement that allows buyers and sellers to discover in sequence and carry out a voluntary replace of goods or services. It is one of the two key institutions that organize trade, along with the right to own goods. In everyday usage, the word market may refer to the place where goods are traded, sometimes known as a marketplace, or to a street market.

In economics a financial market is a device that allows people to easily buy and sell financial securities, commodities, and other fungible substance of value at low transaction costs and at prices that reflect capable markets. A stock market is a market for the trading of company stock, and derivatives of same; both of these are securities scheduled on a stock replace as well as those only traded privately.

Tuesday, July 24, 2007


Electrical resistance is a compute of the degree to which an object opposes an electric current through it. The SI unit of electrical resistance is the ohm. Its reciprocal quantity is electrical conductance calculated in siemens. Electrical resistance shares some conceptual parallels with the mechanical notion of friction.

The resistance of an object determines the amount of current through the object for a known voltage across the object I=V/R, where R is the resistance of the object, measured in ohms, equivalent to J•s/C2, V is the voltage across the object, measured in volts, I is the current through the object, measured in amperes. In metals, the Fermi level lies in the conduction band giving rise to free transfer electrons. However, in semiconductors the position of the fermi level is within the band gap, closely half way between the conduction band minimum and valence band maximum for intrinsic semiconductors.

Wednesday, July 18, 2007


Security is the condition of being sheltered against danger or loss. In the general sense, security is a perception similar to safety. The nuance between the two is an added emphasis on being protected from dangers that initiate from outside. Individuals or actions that encroach upon the condition of protection are responsible for the breach of security.

The word security in general procedure is synonymous with safety, but as a technical term security means that something not only is protected but that it has been secured. A condition that results from the establishment and maintenance of protective measures that ensures a state of inviolability from hostile acts or influences. With respect to classified matter, the condition that prevents unauthorized persons from having right to use to official information that is safeguarded in the benefit of national security.

Thursday, July 12, 2007

Computer file

A computer file is a block of subjective information, or resource for storing information, that is available to a computer program and is usually based on some kind of durable storage. A file is durable in the intelligence that it remains available for programs to use after the current program has finished. Computer files can be considered as the up to date counterpart of paper documents which traditionally were kept in offices and libraries files.

In most computer files are stored on various type of data storage device, there is a hard disk, from which most operating systems run and on which most store their files. Hard discs are the most ever-present form of non-volatile storage at the start of the 21st century. Where files have only temporary information, they may be stored in RAM. The way a computer organizes, names stores and manipulates files is worldwide referred to as its file system. Nearly all computers have at least one file system.

Thursday, July 05, 2007


Electric-powered trams were first successfully experienced in service in Richmond, Virginia, in 1888, in the Richmond Union Passenger Railway built by Frank J. Sprague. There were earlier saleable installations of electric streetcars, including one in Berlin, as early as 1881 by Werner von Siemens and the company that still bears his name, and also one in Saint Petersburg, Russia, made-up and tested by Fyodor Pirotsky in 1880. Another was by John Joseph Wright, brother of the celebrated mining entrepreneur Whitaker Wright, in Toronto in 1883.The earlier installations, however, proved difficult and/or variable. Siemens' line, for example, provided power through a live rail and a return rail, like a model train setup, limiting the voltage that could be used, and providing unwanted stimulation to people and animals crossing the tracks. Siemens later planned his own method of current collection, this time from an overhead wire, called the bow collector.
Once this had been developed his cars became equal to, if not superior than, any of Sprague's cars. The first electric interurban line connecting St. Catherine’s and Thorold, Ontario was operated in 1887, and was measured quite successful at the time. While this line proved quite versatile as one of the earliest fully functional electric streetcar installations, it still required horse-drawn carry while hiking the Niagara Escarpment and for two months of the winter when hydroelectricity was not available. This line continuous service in its original form well into the 1950s.