Great Wall of China

The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups. Several walls have been built since the 5th century BC that are referred to collectively as the Great Wall, which has been rebuilt and maintained from the 5th century BC through the 16th century. One of the most famous is the wall built between 220–206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains; the majority of the existing wall was built during the Ming Dynasty.

The Great Wall stretches from Shanhaiguan in the east, to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has concluded that all the walls measure 8,851.8 km (5,500.3 mi). This is made up of 6,259.6 km (3,889.5 mi) sections of actual wall, 359.7 km (223.5 mi) of trenches and 2,232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.

History

The early walls

Great Wall of the Qin Dynasty

Great Wall of the Han Dynasty

Great Wall of the Ming Dynasty

The Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period, which began around the 8th century BC. During the Warring States Period from the 5th century BCE to 221 BCE, the states of Qin, Wei, Zhao, Qi, Yan and Zhongshan all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames.

Qin Shi Huang conquered all opposing states and unified China in 221 BCE, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls have eroded away over the centuries, and very few sections remain today. The human cost of the construction is unknown, but it has been estimated by some authors that hundreds of thousands, if not up to a million, workers died building the Qin wall. Later, the Han, Sui, and Northern dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders. The Tang and Song Dynasties did not build any walls in the region. The Liao, Jin, and Yuan dynasties, who ruled Northern China throughout most of the 10-13th centuries, had their original power bases north of the Great Wall proper; accordingly, they would have no need throughout most of their history to build a wall along this line. The Liao carried out limited repair of the Great Wall in a few areas, however the Jin did construct defensive walls in the 12th century, but those were located much to the north of the Great Wall as we know it, within today's Inner and Outer Mongolia.

The Ming era

The Great Wall concept was revived again during the Ming Dynasty in the 14th century, and following the Ming army's defeat by the Oirats in the Battle of Tumu in 1449. The Ming had failed to gain a clear upper hand over the Manchurian and Mongolian tribes after successive battles, and the long-drawn conflict was taking a toll on the empire. The Ming adopted a new strategy to keep the nomadic tribes out by constructing walls along the northern border of China. Acknowledging the Mongol control established in the Ordos Desert, the wall followed the desert's southern edge instead of incorporating the bend of the Huang He.

Unlike the earlier Qin fortifications, the Ming construction was stronger and more elaborate due to the use of bricks and stone instead of rammed earth. As Mongol raids continued periodically over the years, the Ming devoted considerable resources to repair and reinforce the walls. Sections near the Ming capital of Beijing were especially strong.

During the 1440s–1460s, the Ming also built a so-called "Liaodong Wall". Similar in function to the Great Wall (whose extension, in a sense, it was), but more basic in construction, the Liaodong Wall enclosed the agricultural heartland of the Liaodong province, protecting it against potential incursions by Jurched-Mongol Oriyanghan from the northwest and the Jianzhou Jurchens from the north. While stones and tiles were used in some parts of the Liaodong Wall, most of it was in fact simply an earth dike with moats on both sides.

Towards the end of the Ming Dynasty, the Great Wall helped defend the empire against the Manchu invasions that began around 1600. Even after the loss of all of Liaodong, the Ming army under the command of Yuan Chonghuan held off the Manchus at the heavily fortified Shanhaiguan pass, preventing the Manchus from entering the Chinese heartland. The Manchus were finally able to cross the Great Wall in 1644, after Beijing had fallen to Li Zicheng's rebels, and the gates at Shanhaiguan were opened by the commanding Ming general Wu Sangui, who hoped to use the Manchus to expel the rebels from Beijing. The Manchus quickly seized Beijing, and defeated both the rebel-founded Shun Dynasty and the remaining Ming resistance, establishing the Qing Dynasty rule over the entire China.

In 2009, an additional 290 km (180 mi) of previously undetected portions of the wall, built during the Ming Dynasty, were discovered. The newly discovered sections range from the Hushan mountains in the northern Liaoning province, to Jiayuguan in western Gansu province. The sections had been submerged over time by sandstorms which moved across the arid region.

Under Qing rule, China's borders extended beyond the walls and Mongolia was annexed into the empire, so construction and repairs on the Great Wall were discontinued. On the other hand, the so-called Willow Palisade, following a line similar to that of the Ming Liaodong Wall, was constructed by the Qing rulers in Manchuria. Its purpose, however, was not defense but rather migration control.

Early Western reports of the wall

The North African traveler Ibn Battuta, who was in Guangzhou ca. 1346, inquired among the local Muslims about the wall that, according to the Qur'an, Dhul-Qarnayn had built to contain Gog and Magog. Ibn Battuta reported that the wall was "sixty days' travel" from the city of Zeitun (Quanzhou); Hamilton Alexander Rosskeen Gibb noted Ibn Battuta has confused the Great Wall of China with that built by Dhul-Qarnayn. This indicated that Arabs may have heard about China's Great Wall during earlier periods of China's history, and associated it with the Gog and Magog wall of the Qur'an. But, in any event, no one of Ibn Battuta's Guangzhou interlocutors had seen the wall or knew anyone who had seen it, which implies that by the late Yuan the existence of the Great Wall was not in the people's living memory, at least not in the Muslim communities in Guangzhou.

Soon after Europeans reached the Ming China in the early 16th century, accounts of the Great Wall started to circulate in Europe, even though no European was to see it with his own eyes for another century. Possibly the earliest description of the wall, and its significance for the defense of the country against the "Tartars" (i.e. Mongols), may be the one contained in the Third Década of João de Barros' Asia (published 1563). Interestingly, Barros himself did not travel to Asia, but was able to use Chinese books brought to Lisbon by Portuguese traders. One of the earliest records of a Western traveler entering China via a Great Wall pass (Jiayuguan, in this case) may be that of the Portuguese Jesuit brother Bento de Góis, who had reached China's north-western gate from India in 1605.

Notable areas

Photograph of the Great Wall in 1907

An area of the sections of the Great Wall at Jinshanling

The Great Wall

Some of the following sections are in Beijing municipality, which were renovated and which are regularly visited by modern tourists today.

• "North Pass" of Juyongguan pass, known as the Badaling. When used by the Chinese to protect their land, this section of the wall has had many guards to defend China’s capital Beijing. Made of stone and bricks from the hills, this portion of the Great Wall is 7.8 meters (26 ft) high and 5 meters (16 ft) wide.
• "West Pass" of Jiayuguan (pass). This fort is near the western edges of the Great Wall.
• "Pass" of Shanhaiguan. This fort is near the eastern edges of the Great Wall.
• One of the most striking sections of the Ming Great Wall is where it climbs extremely steep slopes. It runs 11 kilometers (6.8 mi) long, ranges from 5 to 8 meters (16–26 ft) in height, and 6 meters (20 ft) across the bottom, narrowing up to 5 meters (16 ft) across the top. Wangjinglou is one of Jinshanling's 67 watchtowers, 980 meters (3,220 ft) above sea level.
• South East of Jinshanling, is the Mutianyu Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for approximately 2.25 kilometers (about 1.3 miles). It is connected with Juyongguan Pass to the west and Gubeikou to the east.
• 25 km (16 mi) west of the Liao Tian Ling stands apart of Great Wall which is only 2~3 stories high. According to the records of Lin Tian, the wall was not only extremely short compared to others, but it appears to be silver. Archeologists explain that the wall appears to be silver because the stone they used were from Shan Xi, where many mines are found. The stone contains extremely high levels of metal in it causing it to appear silver. However, due to years of decay of the Great Wall, it is hard to see the silver part of the wall today.

Another notable section lies near the eastern extremity of the wall, where the first pass of the Great Wall was built on the Shanhaiguan (known as the “Number One Pass Under Heaven”). 3 km north of Shanhaiguan is Jiaoshan Great Wall, the site of the first mountain of the Great Wall. 15 km northeast from Shanhaiguan, is the Jiumenkou, which is the only portion of the wall that was built as a bridge.

Characteristics

Before the use of bricks, the Great Wall was mainly built from rammed earth, stones, and wood. During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tiles, lime, and stone. The size and weight of the bricks made them easier to work with than earth and stone, so construction quickened. Additionally, bricks could bear more weight and endure better than rammed earth. Stone can hold under its own weight better than brick, but is more difficult to use. Consequently, stones cut in rectangular shapes were used for the foundation, inner and outer brims, and gateways of the wall. Battlements line the uppermost portion of the vast majority of the wall, with defensive gaps a little over 30 cm (12 in) tall, and about 23 cm (9.1 in) wide.

Condition

The Great Wall at Mutianyu, near Beijing

While some portions north of Beijing and near tourist centers have been preserved and even extensively renovated, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads. Sections of the Wall are also prone to graffiti and vandalism. Parts have been destroyed because the Wall is in the way of construction.

More than 60 km (37 mi) of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In places, the height of the wall has been reduced from more than five meters (16.4 ft) to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud, rather than brick and stone, and thus are more susceptible to erosion.

Watchtowers and barracks

Communication between the army units along the length of the Great Wall, including the ability to call reinforcements and warn garrisons of enemy movements, was of high importance. Signal towers were built upon hill tops or other high points along the wall for their visibility.

Visibility from space

Visibility from the moon

One of the earliest known references to this myth appears in a letter written in 1754 by the English antiquary William Stukeley. Stukeley wrote that, "This mighty wall of four score miles in length (Hadrian's Wall) is only exceeded by the Chinese Wall, which makes a considerable figure upon the terrestrial globe, and may be discerned at the moon." The claim was also mentioned by Henry Norman in 1895 where he states "besides its age it enjoys the reputation of being the only work of human hands on the globe visible from the moon." The issue of "canals" on Mars was prominent in the late 19th century and may have led to the belief that long, thin objects were visible from space. The claim that the Great Wall is visible also appears in 1932's Ripley's Believe it or Not strip and in Richard Halliburton's 1938 book Second Book of Marvels.

The claim the Great Wall is visible has been debunked many times, but is still ingrained in popular culture. The wall is a maximum 9.1 m (30 ft) wide, and is about the same color as the soil surrounding it. Based on the optics of resolving power (distance versus the width of the iris: a few millimeters for the human eye, meters for large telescopes) only an object of reasonable contrast to its surroundings which is 70 mi (110 km) or more in diameter (1 arc-minute) would be visible to the unaided eye from the moon, whose average distance from Earth is 384,393 km (238,851 mi). The apparent width of the Great Wall from the moon is the same as that of a human hair viewed from 2 miles (3.2 km) away. To see the wall from the moon would require spatial resolution 17,000 times better than normal (20/20) vision. Unsurprisingly, no lunar astronaut has ever claimed to have seen the Great Wall from the moon.

Visibility from low earth orbit

A more controversial question is whether the Wall is visible from low earth orbit (an altitude of as little as 100 miles (160 km)). NASA claims that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other man-made objects. Other authors have argued that due to limitations of the optics of the eye and the spacing of photoreceptors on the retina, it is impossible to see the wall with the naked eye, even from low orbit, and would require visual acuity of 20/3 (7.7 times better than normal).

Anecdotal reports

Astronaut William Pogue thought he had seen it from Skylab but discovered he was actually looking at the Grand Canal of China near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye." U.S. Senator Jake Garn claimed to be able to see the Great Wall with the naked eye from a space shuttle orbit in the early 1980s, but his claim has been disputed by several U.S. astronauts. Veteran U.S. astronaut Gene Cernan has stated: "At Earth orbit of 100 miles (160 km) to 200 miles (320 km) high, the Great Wall of China is, indeed, visible to the naked eye." Ed Lu, Expedition 7 Science Officer aboard the International Space Station, adds that, "it's less visible than a lot of other objects. And you have to know where to look."

In 2001, Neil Armstrong stated about the view from Apollo 11: "I do not believe that, at least with my eyes, there would be any man-made object that I could see. I have not yet found somebody who has told me they've seen the Wall of China from Earth orbit. ...I've asked various people, particularly Shuttle guys, that have been many orbits around China in the daytime, and the ones I've talked to didn't see it.

In October 2003, Chinese astronaut Yang Liwei stated that he had not been able to see the Great Wall of China. In response, the European Space Agency (ESA) issued a press release reporting that from an orbit between 160 and 320 km, the Great Wall is visible to the naked eye. In an attempt to further clarify things, the ESA published a picture of a part of the “Great Wall” photographed from Space. However, in a press release a week later (no longer available in the ESA’s website), they acknowledged that the "Great Wall" in the picture was actually a river.

Leroy Chiao, a Chinese-American astronaut, took a photograph from the International Space Station that shows the wall. It was so indistinct that the photographer was not certain he had actually captured it. Based on the photograph, the China Daily later reported that the Great Wall can be seen from space with the naked eye, under favorable viewing conditions, if one knows exactly where to look. However, the resolution of a camera can be much higher than the human visual system, and the optics much better, rendering photographic evidence irrelevant to the issue of whether it is visible to the naked eye.

Allergy

Allergic or hypersensitivity type I is the failure of immune body where one's body becomes hypersensitive in immunology react to the materials generally immunogenic (antigenic) or the person in question is said to be atopic. In other words, the human body to the environment or excessive berkasi materials by the body are considered foreign and dangerous, but it was not for people who are not atopic. Ingredients that cause hypersensitivity is called an allergen .

Allergies are caused by the production of antibodies of IgE type.

Prevention

Some things you can do to prevent allergies:

§ Maintain cleanliness of the environment, both inside and outside the home. This includes not accumulate a lot of stuff in the home or bedroom can become a den of dust accumulation as a stimulus alergi.Usahakan reactions do not keep animals in the house or put a pet cage around your home.

§ Personal hygiene must also be considered, to avoid climbing tertumpuknya which can also be a source of stimulation alergi.Untuk reaction bath, it should use warm water for life, and try to shower the evening before PK.17.00 '. Soap and shampoo are used should be that soap and shampoo to bayi.Dilarang using hair dye.

§ Do not use air freshener or perfume, anti-mosquito drugs. If in your house there are lots of mosquitoes, use anti-mosquito racket.

§ Use a mattress or cushion of foam material, not cotton.

§ Use of cotton bed sheets and wash them at least once a week with warm water will be effective.

§ Avoid using the clothes made from wool, use cotton clothing.

§ Air conditioning (AC) can be used, but should not be too cold and should not be more than PK.24.00 '

§ Keep an eye on any food or beverages or drugs that cause allergic reactions. Avoid food, beverages, and drugs such. You must comply with the rules of your allergy diet.

§ meet the experts. Consult a specialist. Allergies that arise require different treatments to each patient allergies. Ask your doctor to perform immunotherapy to reduce your sensitivity to substances trigger allergic reactions, for example: by using the extract of house dust injection or by performing immunization Guirine Baccillus Calmette (BCG) at least 3 times (1 time a month) in succession, and repeated every 6 months.

STUXNET(new dangour for modren world)

Stuxnet is a Windows-specific computer worm first discovered in July 2010 by VirusBlokAda, a security firm based in Belarus. While it is not the first time that hackers have targeted industrial systems, it is the first discovered worm that spies on and reprograms industrial systems, and the first to include a programmable logic controller (PLC) rootkit. It was specifically written to attack Supervisory Control And Data Acquisition (SCADA) systems used to control and monitor industrial processes. Stuxnet includes the capability to reprogram the PLCs and hide its changes.
The worm's probable target is said to have been high value infrastructures in Iran using Siemens control systems. According to news reports the infestation by this worm might have damaged Iran's nuclear facilities in Natanz and eventually delayed the start up of Iran's Bushehr Nuclear Power Plant. Although Siemens has stated that the worm has not caused any damage, on November 29, Iran confirmed that its nuclear program had indeed been damaged by Stuxnet.
Russian digital security company Kaspersky Labs released a statement that described Stuxnet as "a working and fearsome prototype of a cyber-weapon that will lead to the creation of a new arms race in the world." Kevin Hogan, Senior Director of Security Response at Symantec, noted that 60% of the infected computers worldwide were in Iran, suggesting its industrial plants were the target. Kaspersky Labs concluded that the attacks could only have been conducted "with nation-state support", making Iran the first target of real cyberwarfare.
History
The worm was first reported by the security company VirusBlokAda in mid-June 2010, and roots of it have been traced back to June 2009. It contains a component with a build time stamp from 3 February 2010. In the United Kingdom on 25 November 2010, Sky News reported that it had received information that the Stuxnet worm, or a variation of the virus, had been traded on the black market. The name is derived from some keywords discovered in the software.
Affected countries
A study of the spread of Stuxnet by Symantec showed that the main affected countries as of August 6, 2010 were:
Country Infected computers
China 6,000,000 (unconfirmed) (October 1)
Iran 62,867
Indonesia 13,336
India 6,552
United States 2,913
Australia 2,436
United Kingdom 1,038
Malaysia 1,013
Pakistan 993
Finland 7
Germany 5 (September)
Operation
The complexity of the software is very unusual for malware, and consists of attacks against three different systems:
1. The Windows operating system,
2. An industrial software application that runs on Windows, and
3. A Siemens programmable logic controller (PLC).
The attack requires in-depth knowledge of industrial processes and an interest in attacking industrial infrastructure. These capabilities would have required a team of people to program, as well as check that the malware would not crash the PLCs. Eric Byres, who has years of experience maintaining and troubleshooting Siemens systems, told Wired that writing the code would have taken many man-months, if not years.
Windows infection
Stuxnet attacked Windows systems using four zero-day attacks (plus the CPLINK vulnerability and a vulnerability used by the Conficker worm). It is initially spread using infected removable drives such as USB flash drives, and then uses other exploits and techniques such as peer-to-peer RPC to infect and update other computers inside private networks that are not directly connected to the Internet. The number of zero-day Windows exploits used is unusual, as zero-day Windows exploits are valued, and hackers do not normally waste the use of four different ones in the same worm. Stuxnet is unusually large at half a megabyte in size, and written in different programming languages (including C and C++) which is also irregular for malware. The Windows component of the malware is promiscuous in that it spreads relatively quickly and indiscriminately.
The malware has both user-mode and kernel-mode rootkit capability under Windows, and its device drivers have been digitally signed with the private keys of two certificates that were stolen from separate companies, JMicron and Realtek, that are both located at Hsinchu Science Park in Taiwan. The driver signing helped it install kernel-mode drivers successfully and remain undetected for a relatively long period of time. Both compromised certificates have been revoked by VeriSign.
Two websites were configured as command and control servers for the malware, allowing it to be updated, and for industrial espionage to be conducted by uploading information. Both of these websites have subsequently been taken down as part of a global effort to disable the malware.
Step 7 software infection

Overview of normal communications between Step 7 and a Siemens PLC

Overview of Stuxnet hijacking communication between Step 7 software and a Siemens PLC
Once installed on a Windows system, Stuxnet infects project files belonging to Siemens' WinCC/PCS 7 SCADA control software (Step 7), and subverts a key communication library of WinCC called s7otbxbx.dll. The purpose of this subversion is to intercept communications between the WinCC software running under Windows and the target Siemens PLC devices that the software is able to configure and program when the two are connected via a data cable. In this way, the malware is able to install itself on PLC devices unnoticed, and subsequently to mask its presence from WinCC if the control software attempts to read an infected block of memory from the PLC system.

The malware furthermore used a zero-day exploit in the WinCC/SCADA database software in the form of a hard-coded database password.
PLC infection
Siemens Simatic S7-300 PLC CPU with three modules attached, each of which can control 31 slave variable-frequency drives
The entirety of the Stuxnet code has not yet been understood, but among its peculiar capabilities is a fingerprinting technology which allows it to precisely identify the systems it infects. Stuxnet requires specific slave variable-frequency drives (frequency converter drives) to be attached to the targeted Siemens S7-300 system and its associated modules. It only attacks those PLC systems with variable-frequency drives from two specific vendors: Vacon based in Finland and Fararo Paya based in Iran. Furthermore, it monitors the frequency of the attached motors, and only attacks systems that spin between 807Hz and 1210 Hz. The industrial applications of motors with these parameters are diverse, and may include pumps or centrifuges.
Stuxnet installs malware into memory block DB890 of the PLC that monitors the Profibus messaging bus of the system. When certain criteria are met, it periodically modifies the frequency to 1410 Hz and then to 2 Hz and then to 1064 Hz, and thus affects the operation of the connected motors by changing their rotational speed. It also installs a rootkit that hides the malware on the system—the first such documented case on this platform.
Removal
Siemens has released a detection and removal tool for Stuxnet. Siemens recommends contacting customer support if an infection is detected and advises installing Microsoft patches for security vulnerabilities and prohibiting the use of third-party USB flash drives Siemens also advises immediately upgrading password access codes.
The worm's ability to reprogram external programmable logic controllers (PLCs) may complicate the removal procedure. Symantec's Liam O'Murchu warns that fixing Windows systems may not completely solve the infection; a thorough audit of PLCs is recommended. Despite speculation that incorrect removal of the worm could cause damage, Siemens reports that in the first four months since discovery, the malware was successfully removed from the systems of twenty-two customers without any adverse impact.
Control system security
Main article: Control system security
Prevention of control system security incidentssuch as from viral infections like Stuxnet, is a topic that is being addressed in both the public and the private sector.
The U.S. Department of Homeland Security National Cyber Security Division operates the Control System Security Program (CSSP). The program operates a specialized Computer Emergency Response Team (ICS-CERT), conducts a biannual conference (ICSJWG), provides training, publishes recommended practices, and provides a self-assessment tool.
Several industry organizations and professional societies have published standards and best practice guidelines providing direction and guidance for control system end-users on how to establish a Control System Security management program. The basic premise that all of these documents share is that prevention requires a multi-layered approach, often referred to as "defense-in-depth". The layers include policies & procedures, awareness & training, network segmentation, access control measures, physical security measures, system hardening, e.g., patch management, and system monitoring, anti-virus and IPS. The standards and best practices also all recommend starting with a risk analysis and a control system security assessment. The purpose is to assess the current level of risk and the size of the gap between that risk and what is tolerable. The other purpose of an assessment is to identify the vulnerabilities and develop a prioritized program to eliminate or minimize them.
In response to these concerns, cyber security standards and certifications programs such as ISA 99 and SASecure have been developed to evaluate and certify the security of industrial automation products.
Automation, SCADA and control system developers often use off-the-shelf equipment, software and protocols, integrating and configuring these in different ways for a variety of applications. This "common" approach can make it easier for malware to bring down some vulnerable systems. However, proprietary automation, SCADA and control system developers are able to provide a completely bespoke solution, using new protocols and hardware/software/firmware solutions yet unknown to developers of malware.
Speculations about the target and origin
Symantec estimates that the group developing Stuxnet would have been well-funded, consisting of five to ten people, and would have taken six months to prepare. The Guardian, the BBC and The New York Times all reported that experts studying Stuxnet considered that the complexity of the code indicates that only a nation state would have the capabilities to produce it.
Israel, perhaps through Unit 8200, has been speculated to be the country behind Stuxnet in many media reports and by experts such as Richard Falkenrath, former Senior Director for Policy and Plans within the United States Department of Homeland Security. Some have also referred to several clues in the code such as a concealed reference to the word "MYRTUS", believed to refer to the Myrtle tree, or Hadassah in Hebrew. Hadassah was the birth name of the former Jewish queen of Persia, Queen Esther. However, it may be that the "MYRTUS" reference is simply a misinterpreted reference to SCADA components known as RTUs (Remote Terminal Units) and that this reference is actually "My RTUs"–a management feature of SCADA. Also, the number 19790509 appears once in the code and might refer to the date "1979 May 09", the day Habib Elghanian, a Persian Jew, was executed in Tehran. "Symantec cautions readers on drawing any attribution conclusions. Attackers would have the natural desire to implicate another party." According to the New York Times, a former member of the United States intelligence community speculated that the attack may have been the work of Unit 8200. Yossi Melman, who covers intelligence for the Israeli daily newspaper Haaretz and is at work on a book about Israeli intelligence, also suspected that Israel was involved. He noted that Meir Dagan, head of the national intelligence agency Mossad, had his term extended in 2009 because he was said to be involved in important projects. Additionally, in the past year Israeli estimates of when Iran will have a nuclear weapon had been extended to 2014. "They seem to know something, that they have more time than originally thought”, he added.
Additionally, in 2009, a year before Stuxnet was discovered, Scott Borg of the United States Cyber-Consequences Unit (US-CCU) had suggested that Israel might prefer to mount a cyber-attack rather than a military strike on Iran's nuclear facilities. According to Borg this kind of attack could involve disrupting sensitive equipment such as centrifuges using malware introduced via infected memory sticks: "Since the autumn of 2002, I have regularly predicted that this sort of cyber-attack tool would eventually be developed ... Israel certainly has the ability to create Stuxnet and there is little downside to such an attack, because it would be virtually impossible to prove who did it. So a tool like Stuxnet is Israel's obvious weapon of choice." There has also been speculation on the involvement of NATO, the United States and other Western nations. It has been reported that the United States, under one of its most secret programs, initiated by the Bush administration and accelerated by the Obama administration, has sought to destroy Iran's nuclear program by novel methods such as undermining Iranian computer systems. However, solid evidence pointing to Western (and specifically American) involvement has been scarce.
Though Israel has not publicly commented on the Stuxnet attack, it has since confirmed that cyberwarfare is now among the pillars of its defense doctrine, with a military intelligence unit set up to pursue both defensive and offensive options.
Symantec has reported that the majority of infected systems were in Iran (about 60%),which has led to speculation that it may have been deliberately targeting "high-value infrastructure" in Iran including either the Bushehr Nuclear Power Plant or the Natanz nuclear facility. Ralph Langner, a German cyber-security researcher, called the malware "a one-shot weapon" and said that the intended target was probably hit, although he admitted this was speculation.
There are reports that Iran's uranium enrichment facility at Natanz was the target of Stuxnet and the site sustained damage because of it, causing a sudden 15% reduction in its production capabilities. There was also a previous report by WikiLeaks disclosing a "serious nuclear accident" at the site in 2009. According to statistics published by the Federation of American Scientists (FAS) the number of enriched centrifuges operational in Iran mysteriously declined from about 4,700 to about 3,900 beginning around the time the nuclear incident WikiLeaks mentioned would have occurred. On November 23 it was announced that uranium production at Natanz in Iran temporarily ceased altogether because of a series of major technical problems. According to a report by the Institute for Science and International Security (ISIS) Stuxnet is "a reasonable explanation for the apparent damage" at Natanz and may have destroyed up to 1000 centrifuges (10 percent) in the months before January 2010. The authors conclude:
"The attacks seem designed to force a change in the centrifuge’s rotor speed, first raising the speed and then lowering it, likely with the intention of inducing excessive vibrations or distortions that would destroy the centrifuge. If its goal was to quickly destroy all the centrifuges in the FEP, Stuxnet failed. But if the goal was to destroy a more limited number of centrifuges and set back Iran’s progress in operating the FEP, while making detection difficult, it may have succeeded, at least temporarily."
The ISIS report further notes that Iranian authorities have attempted to conceal the breakdown by installing new centrifuges on a large scale.
Iranian reaction
The Associated Press reported that the semi-official Iranian Students News Agency released a statement on 24 September 2010 stating that experts from the Atomic Energy Organization of Iran met in the previous week to discuss how Stuxnet could be removed from their systems. According to analysts, Western intelligence agencies have been attempting to sabotage the Iranian nuclear program for some time.
The head of the Bushehr Nuclear Power Plant told Reuters that only the personal computers of staff at the plant had been infected by Stuxnet and the state-run newspaper Iran Daily quoted Reza Taghipour, Iran's telecommunications minister, as saying that it had not caused "serious damage to government systems". The Director of Information Technology Council at the Iranian Ministry of Industries and Mines, Mahmud Liaii, has said that: "An electronic war has been launched against Iran... This computer worm is designed to transfer data about production lines from our industrial plants to locations outside Iran."
It is believed that infection originated from Russian laptops belonging to Russian contractors at the site of Bushehr power plant and spreading from there with the aim of targeting the power plant control systems. In response to the infection, Iran has assembled a team to combat it. With more than 30,000 IP addresses affected in Iran, an official has said that the infection is fast spreading in Iran and the problem has been compounded by the ability of Stuxnet to mutate. Iran has set up its own systems to clean up infections and has advised against using the Siemens SCADA antivirus since it is suspected that the antivirus is actually embedded with codes which update Stuxnet instead of eradicating it.
According to Hamid Alipour, deputy head of Iran's government Information Technology Company, "The attack is still ongoing and new versions of this virus are spreading." He reports that his company had begun the cleanup process at Iran's "sensitive centres and organizations. We had anticipated that we could root out the virus within one to two months, but the virus is not stable, and since we started the cleanup process three new versions of it have been spreading," he told the Islamic Republic News Agency.
Although he did not mention Stuxnet by name, on Monday November 29, 2010, Iranian President Mahmoud Ahmadinejad for the first time admitted that malicious software code had damaged Iran's centrifuge facilities. "They succeeded in creating problems for a limited number of our centrifuges with the software they had installed in electronic parts," Mr. Ahmadinejad told reporters at a news conference, Reuters reported. "They did a bad thing. Fortunately our experts discovered that and today they are not able [to do that] anymore.
On the same day two Iranian nuclear scientists were assassinated when bombs were attached to their cars in Tehran. Wired speculated that the assassinations could indicate that whoever was behind Stuxnet felt that it was not sufficient to stop the nuclear program.

HIV AND AIDS

What Is It?

AIDS is one of the most serious, deadly diseases in human history.

More than 20 years ago, doctors in the United States identified the first cases of AIDS in San Francisco and New York. Now there are an estimated 42 million people living with HIV or AIDS worldwide, and more than 3 million die every year from AIDS-related illnesses.

AIDS is caused by the human immunodeficiency virus (HIV). HIV destroys a type of defense cell in the body called a CD4 helper lymphocyte (pronounced: lim-fuh-site). These lymphocytes are part of the body's immune system, the defense system that fights infectious diseases. But as HIV destroys these lymphocytes, people with the virus begin to get serious infections that they normally wouldn't — that is, they become immune deficient. The name for this condition is acquired immunodeficiency syndrome(AIDS).

As the medical community learns more about how HIV works, they've been able to develop drugs to inhibit it (meaning they interfere with its growth). These drugs have been successful in slowing the progress of the disease, and people with the disease now live much longer. But there is still no cure for HIV and AIDS.

Hundreds of U.S. teens become infected with HIV each year. HIV can be transmitted from an infected person to another person through blood, semen (also known as "cum," the fluid released from the penis when a male ejaculates), vaginal fluids, and breast milk.

The virus is spread through high-risk behaviors including:

· unprotected oral, vaginal, or anal sexual intercourse ("unprotected" means not using a condom)

· sharing needles, such as needles used to inject drugs (including needles used for injecting steroids) and those used for tattooing

People who have another sexually transmitted disease, such as syphilis, genital herpes, chlamydia, gonorrhea, or bacterial vaginosis are at greater risk for getting HIV during sex with infected partners.

If a woman with HIV is pregnant, her newborn baby can catch the virus from her before birth, during the birthing process, or from breastfeeding. If doctors know an expectant mother has HIV, they can usually prevent the spread of the virus from mother to baby. All pregnant teens and women should be tested for HIV so they can begin treatment if necessary.

How Does HIV Affect the Body?

A healthy body is equipped with CD4 helper lymphocyte cells (CD4 cells). These cells help the immune system function normally and fight off certain kinds of infections. They do this by acting as messengers to other types of immune system cells, telling them to become active and fight against an invading germ.

HIV attaches to these CD4 cells, infects them, and uses them as a place to multiply. In doing so, the virus destroys the ability of the infected cells to do their job in the immune system. The body then loses the ability to fight many infections.

Because their immune systems are weakened, people who have AIDS are unable to fight off many infections, particularly tuberculosis and other kinds of otherwise rare infections of the lung (such as Pneumocystis carinii pneumonia), the surface covering of the brain (meningitis), or the brain itself (encephalitis). People who have AIDS tend to keep getting sicker, especially if they are not taking antiviral medications properly.

AIDS can affect every body system. The immune defect caused by having too few CD4 cells also permits some cancers that are stimulated by viral illness to occur — some people with AIDS get forms of lymphoma and a rare tumor of blood vessels in the skin called Kaposi's sarcoma. Because AIDS is fatal, it's important that doctors detect HIV infection as early as possible so a person can take medication to delay the onset of AIDS.

How Do People Know They Have HIV?

Once a person's blood lacks the number of CD4 cells required to fight infections, or the person has signs of specific illnesses or diseases that occur in people with HIV infection, doctors make a diagnosis of AIDS.

Severe symptoms of HIV infection and AIDS may not appear for 10 years. And for years leading up to that, a person may not have symptoms of AIDS. The amount of time it takes for symptoms of AIDS to appear varies from person to person. Some people may feel and look healthy for years while they are infected with HIV. It is still possible to infect others with HIV, even if the person with the virus has absolutely no symptoms. You cannot tell simply by looking at someone whether he or she is infected.

When a person's immune system is overwhelmed by AIDS, the symptoms can include:

· extreme weakness or fatigue

· rapid weight loss

· frequent fevers that last for several weeks with no explanation

· heavy sweating at night

· swollen lymph glands

· minor infections that cause skin rashes and mouth, genital, and anal sores

· white spots in the mouth or throat

· chronic diarrhea

· a cough that won't go away

· trouble remembering things

Girls may also experience severe vaginal yeast infections that don't respond to usual treatment, as well as pelvic inflammatory disease (PID).

How Can It Be Prevented?

One of the reasons that HIV is so dangerous is that a person can have the virus for a long time without knowing it. That person can then spread the virus to others through high-risk behaviors. HIV transmission can be prevented by:

· abstaining from sex (not having oral, vaginal, or anal sex)

· always using latex condoms for all types of sexual intercourse

· avoiding contact with the bodily fluids through which HIV is transmitted

· never sharing needles

How Do Doctors Test for and Treat HIV?

If you think that you may have HIV or AIDS or if you have had a partner who may have HIV or AIDS, see your family doctor, adolescent doctor, or gynecologist. He or she will talk with you and perform tests. The doctor may do a blood test or a swab of the inside of your cheek. Depending on what type of test is done, results may take from a few hours to several days. Let the doctor know the best way to reach you confidentially with any test results.

People can also get tested for HIV/AIDS at special AIDS clinics around the country. Clinics offer both anonymous (meaning the clinic doesn't know a person's name) and confidential (meaning they know who a person is but keep it private) testing. Most AIDS testing centers will ask you to follow up for counseling to get your results, whether the test is negative or positive.

If you're not sure how to find a doctor or get an AIDS test, you can contact the National AIDS Hotlines at (800) 342-AIDS (English) or (800) 344-7432 (Spanish). A specialist there will explain what you should do next.

There is no cure for AIDS, which makes prevention so important. Combinations of antiviral drugs and drugs that boost the immune system have allowed many people with HIV to resist infections, stay healthy, and prolong their lives, but these medications are not a cure. Right now there is no vaccine to prevent HIV and AIDS, although researchers are working on developing one.