Abdulaziz Al-Basseet

Antivirus software (or anti-virus) is computer software used to identify and remove computer viruses, as well as many other types of harmful computer software, collectively referred to as malware. While the first antivirus software was designed exclusively to combat computer viruses, most modern antivirus software can protect against a wide range of malware, including worms, rootkits, and trojans. There are competing claims for the innovator of the first antivirus product. Perhaps the first publicly-known neutralization of a wild PC virus was performed by Bernt Fix (also Bernd) in early 1987. Fix neutralized an infection of the Vienna virus.^{[1] [2]} The first edition of a antivirus program to detect and repair the cipap mks_vir was released in 1987; the program was only available with a Polish interface. Autumn 1988 saw antivirus software Dr. Solomon’s Anti-Virus Toolkit released by Briton Alan Solomon. Also in 1988 AIDSTEST and AntiVir were released. By December 1990, the market had matured to the point of nineteen separate antivirus products being on sale including Norton AntiVirus and VirusScan from McAfee.

Coastal erosion is the wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage (see also beach evolution). Waves, generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion nearby. The study of erosion and sediment redistribution is called ‘coastal morphodynamics’. It may be caused by hydraulic action, abrasion, and corrosion.

On rocky coasts, coastal erosion results in dramatic rock formations in areas where the coastline contains rock layers or fracture zones with different resistances to erosion. Softer areas become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars.

On sedimentary coasts, coastal erosion typically poses more of a danger to human settlements than it does to nature itself. Dunwich, the capital of the English medieval wool trade, disappeared over the space of a few centuries due to redistribution of sediment by waves. Human interference can also increase coastal erosion: Hallsands in Devon, England, was a coastal village that was washed away overnight, an event possibly exacerbated by dredging of shingle in the bay in front of it.

The California coast, which has soft cliffs of sedimentary rock and is heavily populated, regularly has incidents of housing damage as cliffs erode. Damage in Pacifica is shown at left. Devil’s Slide, Santa Barbara and Malibu are regularly affected.

The Holderness coastline on the east coast of England, just north of the Humber Estuary, is the fastest eroding coastline in Europe due to its soft clay cliffs and powerful waves. Groynes and other artificial measure to keep it under control has only sped up the process further down the coast, because longshore drift starves the beaches of sand, leaving them more exposed.

A central processing unit (CPU) or processor is an electronic circuit that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term “CPU” ever came into widespread usage. The term itself and its initialism have been in use in the computer industry at least since the early 1960s (Weik 1961). The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation has remained much the same.

Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, computer. However, this costly method of designing custom CPUs for a particular application has largely given way to the development of mass-produced processors that are made for one or many purposes. This standardization trend generally began in the era of discrete transistor mainframes and minicomputers and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in everything from automobiles to cell phones to children’s toys.