Types Of Computer Viruses Essays - Computer Viruses, Free Essays

Types Of Computer Viruses Essays - Computer Viruses, Free Essays Types Of Computer Viruses A computer virus is a program that is designed to damage your computer, programs, and files. Like a virus in a living thing, a computer virus can spread if it is not removed. Some viruses are more dangerous than others. One of the most common places for a computer virus to appear is on a file found on the Internet or attached to an E-mail. For example, you may have a virus that just pops a message box on your screen, and then the virus is disabled, or you can have a virus that deletes half of your hard drive. Computer viruses didnt really exist until the mid 1980s. The first computer viruses were created in university labs to demonstrate how much of a threat the vicious code could be. There are many kind of viruses that exist today. Some of the most common of Computer Viruses are: File Viruses, Boot Sector/Partition Viruses, Multi-Partite Viruses, Trojan Horses, File Overwriters, Polymorphic viruses, and Stealth Viruses. A File Virus is the most common kind of virus. These kinds of viruses usually infect .EXE and .COM files, which are the main component of a program or application. A file virus can insert its own code into part of the file, so that when the infected program file is run, the virus is executed first. Most file viruses are memory resident. Because of this, they can easily attach themselves to other programs that are being run and start to infect that file. A simple virus will overwrite and destroy a host file, immediately letting the user know that there is a problem because the software will not run. Because these viruses are immediately sensed by the computer, they have a less chance to spread. More complex written viruses will cause more damage, spread easier, and are harder to be detected. Boot sector viruses infect hard drives and floppy disks by putting itself on the boot sector of the disk, which has the code that is run at boot up. Booting up from an infected floppy, allows the virus to jump from the floppy to the hard drive. These viruses are loaded first, and gain control of the system before MS-DOS could be loaded. Since the virus is run before the operating system, it is not MS-DOS-specific and can infect any PC operating system. These viruses stay in the RAM and infects every disk that is read by the computer until the computer is rebooted. After reboot the virus is removed from memory. Multi-Partite Viruses are the worse of both file and boot sector viruses. They can infect the host software components. These viruses spread like a file virus, but still insert itself into a boot sector or partition table. Because of this, they are difficult to remove. An example of this type of virus is the Tequila virus. Trojan Horses are the worst kind of viruses that exist. They contain malicious code that is meant to damage your computer. Unlike other viruses, this virus does not replicate itself. This virus waits until the trigger event. When the trigger event occurs, a message is displayed or files are damaged. Because of the nature of these viruses, there are some researchers that do not classify Trojan Horses as viruses. File Overwriters are viruses that link themselves to a program, leaving the original code intact and adding themselves over and over to as many files as possible. These viruses are made simply to keep copying itself. While, this virus is copying itself it is taking up more disk space and slowing down performance. Since these viruses often have flaws in them, they can inadvertently damage or destroy data. The worst kind of file overwriters, wait until the trigger event, then start to destroy files. Most of the viruses that exist today are Polymorphic. Recently a Mutation Engine was released. This software ensures that polymorphic viruses will only proliferate over the next few years. Like the human AIDS virus, polymorphic viruses grows fast to escape detection by anti-virus programs. Special encrypted code within this virus allows the virus to hide from detection. There are a limited number of kinds of polymorphic viruses. Because of this, they are easier to notice. An example

Geography at Harvard

Geography at Harvard In the latter half of the 20th century, geography as an academic discipline suffered greatly, especially in American higher education. The reasons for this are undoubtedly many, but the biggest contributor was arguably a decision made at Harvard University in 1948 in which university President James Conant declared geography to be not a university subject. In the ensuing decades, universities began dropping geography as an academic discipline until it was no longer found in the nations top schools. But American Geographer, Carl Sauer, wrote in the opening paragraph of Education of a Geographer that the interest [in geography] is immemorial and universal; should we [geographers] disappear, the field will remain and not become vacant. Such a prediction is bold to say the very least. But, is Sauers assertion true? Could geography, with all its historical and contemporary importance, withstand an academic hit like it took at Harvard? What Happened At Harvard? Several key figures emerge in this debate. The first was President James Conant. He was a physical scientist, used to the rigorous nature of research and the employment of a distinct scientific methodology, something which geography was accused of lacking at that time. His charge as the president was to guide the university through the financially lean times in the post-World War II years. The second key figure is Derwent Whittlesey, the chair of the geography department. Whittlesey was a human geographer, for which he was heavily criticized. Physical scientists at Harvard, including many geographers and geologists, felt that human geography was unscientific, lacked rigor, and was not deserving of a place at Harvard. Whittlesey also had a sexual preference which was not as widely accepted in 1948. He hired his live-in partner, Harold Kemp, as a geography lecturer for the department. Kemp was considered by many a mediocre scholar which lent support to geographys critics. Alexander Hamilton Rice, another figure in the Harvard geography affair, founded the Institute for Geographical Exploration at the university. He was considered by many to be a charlatan and would often leave on an expedition while he was supposed to be teaching classes. This made him an annoyance to President Conant and the Harvard administration and did not help geographys reputation. Also, prior to founding the institute, Rice and his wealthy wife tried buying the presidency of the American Geographical Society, contingent on Isaiah Bowman, chair of the geography department at Johns Hopkins University, being removed from the position. Ultimately the plan did not work but the incident did create tension between Rice and Bowman. Isaiah Bowman was a graduate of the geography program at Harvard and was a promoter of geography, just not at his alma mater. Years earlier, a work of Bowmans had been rejected by Whittlesey for use as a geography textbook. The rejection led to an exchange of letters which strained relations between them. Bowman was also described as puritanical and it is supposed that he did not like Whittleseys sexual preference. He also did not like Whittleseys partner, a mediocre scholar, being associated with his alma mater. As a distinguished alumnus, Bowman was part of the committee to evaluate geography at Harvard. It is widely considered that his actions on the geography evaluation committee effectively ended the department at Harvard. Geographer Neil Smith wrote in 1987 that Bowmans silence condemned Harvard Geography and later, when he tried to resuscitate it, his words put nails in the coffin. But, Is Geography Still Being Taught At Harvard? Four Traditions of Geography Earth Science Tradition - earth, water, atmosphere, and relationship to the sunMan-land Tradition - humans and the environment, natural hazards, population, and environmentalismArea Studies Tradition - world regions, international trends, and global relationshipsSpatial Tradition - spatial analysis, geographic information systems Researching Harvard academics online reveals the degree courses for each program are included to show the geographic nature of material being taught within them. Its also important to note that geography was likely ousted at Harvard because of clashing personalities and budgets cuts, not because it wasnt an important academic subject. One could say that it was up to geographers to defend the reputation of geography at Harvard and they failed. Now it is up to those who believe in the merits of geography to reinvigorate it in American education by encouraging and promoting geographic teaching and literacy and supporting rigorous geography standards in schools. This article is adapted from a paper, Geography at Harvard, Revisited, also by the author. Important References: Annals of the Association of American Geographers Vol. 77 no. 2 155-172. Vol. 77 no. 2 155-172.