Thus abridge to the second language is built on deep structural foundations.
Apart from being much more accurate, such linguistic-knowledge enginesshould, in theory, be reversible—you should be able to work backwards from thetarget language to the source language. In practice, there are a few catches whichprevent this from happening as well as it might - but the architecture does at least
make life easier for software designers trying to produce matching pairs of programs.
Tsunami (English to Japanese) and Typhoon Japanese to English), for instance, sharemuch of their underlying programming code.
Having been designed from the start for use on a personal computer ratherthan a powerful workstation or even a mainframe, Tsunami and Typhoon use memory
extremely efficiently. As a result, they are blindingly fast on the latest PCs—translating either way at speeds of more than 300,000 words an hour. Do they produceperfect translations at the click of a mouse? Not by a long shot. But they do come upwith surprisingly good first drafts for expert translators to get their teeth into. Onemistake that the early researchers made was to imagine that nothing less than flawless,fully automated machine translation would suffice. With more realistic expectations,machine translation is, at last, beginning to thrive.
IBM promises science 500-fold break-through in supercomputing power
PC MAGAZINE March 8, 2005.
Biologists hail SI 00 million project to build a "petaflop" computer as likely to
revolutionize our understanding of cellular biology. The computer, nicknamed 'Blue
Genes', world be around 500 times faster than today's most powerful supercomputer.
Computer scientists say that the planned machine, details of which were revealed last:
week, is the first large leap in computer architecture in decades.
IBM will build the programme around the challenge of modeling protein
folding (see below), with much of the research costs going on designing software. It
will involve 50 scientists from IBM Research's Deep Computing Institute and
Computational Biology Group, and unnamed outside academics.
But Blue Gene's hardware will not he customized to the problem and, if IBM's
blueprint works, it will offer all scientific disciplines petaflop computers. These will
be capable of more than one quadrillion floating point operations ('flop') per second -
around two million times more powerful than today's top desktops. Most experts
have" predicted that fundamental technological difficulties would prevent a petaflop
authorities on computer architecture, applauds IBM's approach. "It has made very big
steps in rethinking computer architecture to try to do without the components that
consume power, it has taken all these research ideas and pulled them together."
Antiviruses.Principle of work.Examples of antiviruses.
Antivirus software consists of computer programs that attempt to identify,
thwart and eliminate computer viruses and other malicious software (malware).
Antivirus software typically uses two different techniques to accomplish this:
• Examining (scanning) files to look for known viruses matching definitions in a virus
• Identifying suspicious behavior from any computer program which might indicate
infection. Such analysis may include data captures, port monitoring and other methods.
Most commercial antivirus software uses both of these approaches, with an
emphasis on the virus dictionary approach.
Historically, the term antivirus has also been used for computer viruses that
spread and combated malicious viruses. This was common on the Amiga computer
In the virus dictionary approach, when the antivirus software looks at a file, it
refers to a dictionary of known viruses that the authors of the antivirus software have
identified. If a piece of code in the file matches any virus identified in the dictionary,
then the antivirus software can take one of the following actions:
• attempt to repair the file by removing the virus itself from the file
• quarantine the file (such that the file remains inaccessible to other programs and its
virus can no longer spread)
• delete the infected file
To achieve consistent success in the medium and long term, the virus dictionary
approach requires periodic (generally online) downloads of updated virus dictionary
entries. As civically minded and technically inclined users identify new viruses "in the
wild", they can send their infected files to the authors of antivirus software, who then
include information about the new viruses in their dictionaries.
Dictionary-based antivirus software typically examines files when the computer's operating system creates, opens, closes or e-mails them. In this way it can detect a known virus immediately upon receipt. Note too that a System Administrator can typically schedule the antivirus software to examine (scan) all files on the computer's hard disk on a regular basis. Although the dictionary approach can effectively contain virus outbreaks in the right circumstances, virus authors have tried to stay a step ahead of such software by writing "oligomorphic", "polymorphic" and more recently "metamorphic" viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so as not to match the virus's signature in the dictionary.
The suspicious behavior approach, by contrast, doesn't attempt to identify
known viruses, but instead monitors the behavior of all programs. If one program tries
to write data to an executable program, for example, the antivirus software can flag
this suspicious behavior, alert a user and ask what to do.
Unlike the dictionary approach, the suspicious behavior approach therefore
provides protection against brand-new viruses that do not yet exist in any virus
dictionaries. However, it can also sound a large number of false positives, and users
probably become desensitized to all the warnings. If the user clicks "Accept" on every
such warning, then the antivirus software obviously gives no benefit to that user. This
problem has worsened since 1997, since many more nonmalicious program designs
came to modify other .exe files without regard to this false positive issue. Thus, most
modern antivirus software uses this technique less and less.
Some antivirus-software uses of other types of heuristic analysis. For example,
it could try to emulate the beginning of the code of each new executable that the
system invokes before transferring control to that executable. If the program seems to
use self-modifying code or otherwise appears as a virus (if it immediately tries to find
affected by the Lehigh virus, and both .com and .exe files were affected by the
Jemsalem virus).Tippett's company Certus International Corp. then began to create
anti-virus software programs. The company was sold in 1992 to Symantec Corp, and
Tippett went to work for them, incorporating the software he had developed into
Symantec's product, Norton AntiVirus.
Best antivirus soft
NOD32 is an antivirus package made by the Slovak company Eset. Versions are available for Microsoft Windows, Linux, FreeBSD and other platforms. Remote
administration tools for multiuser installations are also available at extra cost. NOD32
Enterprise Edition consists of NOD32 AntiVirus and NOD32 Remote Administrator.
The NOD32 Remote Administrator program allows a network administrator to
monitor anti-virus functions, push installations and upgrades to unprotected PCs on
the network and update configuration files from a central location.
NOD32 is certified by ICSA Labs. It has been tested 44 times by Virus Bulletin
and has failed only 3 times, the lowest failure rate in their tests. At CNET.com, it
received a review of 7.3/10.
NOD32 consists of an on-demand scanner and four different real-time monitors.
The on-demand scanner (somewhat confusingly referred to as NOD32) can be
invoked by the scheduler or by the user. Each real-time monitor covers a different
virus entry point:
AMON (Antivirus MONitor) - scans files as they are accessed by the system,
preventing a virus from executing on the system.
DMON (Document MONitor) - scans Microsoft Office documents and files for macro
viruses as they are opened and saved by Office applications.
IMON (Internet MONitor) - intercepts traffic on common protocols such as POPS and
HTTP to detect and intercept viruses before they are saved to disc.
XMON (MS eXchangeMONitor) - scans incoming and outgoing mail when NODS 2
is running and licensed for Microsoft Exchange Server – i.e, running on a server
environment. This module is not present on workstations at all.
NOD32 Virus Detection Alert
NOD32 is written largely in assembly code, which contributes to its low use of system resources and high scanning speed, meaning that NOD32 can easily process more than 23MB per second while scanning on a modest P4 based PC and on average, with all real-time modules active, uses less than 20MB of memory in total but the physical RAM used by NOD32 is often just a third of that. According to a 2005 Virus Bulletin test, NOD32 performs scans two to five times faster than other antivirus competitors.
In a networked environment NOD32 clients can update from a central "mirror server" on the network, reducing bandwidth usage since new definitions need only be
downloaded once by the mirror server as opposed to once for each client.
NOD32's scan engine uses heuristic detection (which Eset calls "ThreatSense") in
addition to signature files to provide better protection against newly released viruses.
What is a virus?
IOWA STATE UNIVERSITY, PM 1789 Rewised June, 2006.
In 1983, researcher Fred Cohen defined a computer virus as "a program that can
'infect' other programs by modifying them to include a ... version of itself. " This
means that viruses copy themselves, usually by encryption or by mutating slightly
each time they copy.
There are several types of viruses, but the ones that are the most dangerous are
designed to corrupt your computer or software programs. Viruses can range from an
irritating message flashing on your computer screen to eliminating data on your hard
drive. Viruses often use your computer's internal clock as a trigger. Some of the most
popular dates used are Friday the 13th and famous birthdays. It is important to
remember that viruses are dangerous only if you execute (start) an infected program.
There are three main kinds of viruses*. Each kind is based on the way the virus
1. Boot Sector Viruses - These viruses attach themselves to floppy disks and
then copy themselves into the boot sector of your hard drive. (The boot sector is the
set of instructions your computer uses when it starts up.) When you start your
computer (or reboot it) your hard drive gets infected. You can get boot sector viruses
only from an infected floppy disk. You cannot get one from sharing files or executing
programs. This type of virus is becoming less common because today's computers do
not require a boot disk to start, but they can still be found on disks that contain other
types of files. One of the most common boot sector viruses is called "Monkey," also
known as "Stoned."
2. Program Viruses - These viruses (also known as traditional file viruses)