User:Ashvidia

[edit] Atmospheric Water Generator Or WaterMaker

--Ashvidia 11:56, 7 February 2006 (UTC)

Imagine a machine that can produce pure drinking water from air....

That's right the meaning of the term "Atmospheric water generator" is contained in the above qouted line itself. It is a machine that extracts the moisture from the air, condenses it to liquid water, then purifies and dispenses; what can be called the purest form of potable drinking water.

An atmospheric water generator (AWG) or water maker (WM) is a machine that produces pure drinking water from the air we breathe, in other words from atmospheric moisture. An AWG operates in a manner very similar to that of a refrigerative dehumidifer: air is passed through a cooled coil, causing water to condense. The amount of water that can be produced depends on the humidity, the volume of air passing through the coils, and the size of the machine.

Benefits of an AWG

• Needs no water source.
• Generates 20 litres to unlimited quantity in 24 hours
• Is designed for maximum cost efficiency
• Contains no harmful minerals or chemicals
• Can be powered by solar energy

For more info visit: Atmospheric water generator

[edit] Articles initiated

• Atmospheric water generator
• Indian Standards Institute
• Bureau of Indian Standards

[edit] Articles improved upon

• Indian Statistical Institute
• Actuarial Society Of India
• Barcode

[edit] AIDS

Image:AIDSname.jpg

[edit] What is HIV?

HIV is the ‘Human Immunodeficiency Virus’ that causes AIDS. A member of a group of viruses called retroviruses, HIV infects human cells and uses the energy and nutrients provided by those cells to grow and reproduce. The virus enters the body through the blood and usually attacks a specific type of white blood cell (called the T-helper cell). When HIV attacks this cell, the body loses its ability to fight diseases that would only rarely affect a healthy person.

[edit] What is AIDS?

AIDS (acquired immunodeficiency syndrome) is a disease in which the body's immune system breaks down and is unable to fight off certain infections, known as "opportunistic infections," and other illnesses that take advantage of a weakened immune system. As a result, the body cannot defend itself against infections (like pneumonia). When a person is infected with HIV, the virus enters the body and lives and multiplies primarily in the white blood cells. These immune cells normally protect us from disease. The hallmark of HIV infection is the progressive loss of a specific type of immune cell called T-helper or CD4 cells. As the virus grows, it damages or kills these and other cells, weakening the immune system and leaving the individual vulnerable to various opportunistic infections and other illnesses, ranging from pneumonia to cancer. There may be a long period between the time a person is infected and the time he or she begins to get sick. Most people, who become infected, however, will eventually get sick. The U.S. Centres for Disease Control and Prevention (CDC) defines someone as having a clinical diagnosis of AIDS if they have tested positive for HIV and meet one or both of these conditions: • They have experienced one or more AIDS-related infections or illnesses • The number of CD4 cells has reached or fallen below 200 per cubic millimetre of blood (a measurement known as T-cell count).

[edit] What does HIV look like?

Outside of a human cell, HIV exists as roughly spherical particles (sometimes called virions). The surface of each particle is studded with lots of little spikes.

An HIV particle is around 100-150 billionths of a metre in diameter. That's about the same as:

• 0.1 microns
• 4 millionths of an inch
• One twentieth of the length of an E. coli bacterium
• One seventieth of the diameter of a human CD4+ white blood cell.

Unlike most bacteria, HIV particles are much too small to be seen through an ordinary microscope. However, they can be seen clearly with an electron microscope.

[edit] The structure of HIV

HIV particles surround themselves with a coat of fatty material known as the viral envelope (or membrane). Projecting from this are around 72 little spikes, which are formed from the proteins gp120 and gp41. Just below the viral envelope is a layer called the matrix, which is made from the protein p17.

The viral core (or capsid) is usually bullet-shaped and is made from the protein p24. Inside the core are three enzymes required for HIV replication called reverse transcriptase, integrase and protease. Also held within the core is HIV's genetic material, which consists of two identical strands of RNA.

[edit] How does HIV replicate?

• Entry:

HIV can only replicate inside human cells. The process typically begins when a virus particle bumps into a cell that carries on its surface a special protein called CD4. The spikes on the surface of the virus particle stick to the CD4 and allow the viral envelope to fuse with the cell membrane. The contents of the HIV particle are then released into the cell, leaving the envelope behind.

• Reverse Transcription and Integration:

Once inside the cell, the HIV enzyme reverse transciptase converts the viral RNA into DNA, which is compatible with human genetic material. This DNA is transported to the cell's nucleus, where it is spliced into the human DNA by the HIV enzyme integrase. Once integrated, the HIV DNA is known as provirus.

• Transcription and Translation:

HIV provirus may lie dormant within a cell for a long time. However, when the cell becomes activated, it treats HIV genes in much the same way as human genes. First, it converts them into messenger RNA (using human enzymes). Then the messenger RNA is transported outside the nucleus, and is used as a blueprint for producing new HIV proteins and enzymes.

• Assembly, Budding and Maturation:

Among the strands of messenger RNA produced by the cell are complete copies of HIV genetic material. These gather together with newly made HIV proteins and enzymes to form new viral particles, which are then released from the cell. The enzyme protease plays a vital role at this stage of HIV's life cycle by chopping up long strands of protein into smaller pieces, which are used to construct mature viral cores. The newly matured HIV particles are ready to infect another cell and begin the replication process all over again. In this way, the virus quickly spreads through the human body. And once a person is infected, they can pass HIV on to others in their bodily fluids.

[edit] Origins of AIDS

The origin of AIDS and HIV has puzzled scientists ever since the illness first came to light in the early 1980s. The first recognised cases of AIDS occurred in the USA in the early 1980s. At this time, AIDS did not yet have a name, but it quickly became obvious that few men were suffering from a common syndrome. The discovery of HIV, the Human Immunodeficiency Virus that causes AIDS was made soon after. While some were initially resistant to the connection (and indeed remain so today), there is now clear evidence to prove that HIV does cause AIDS.

Where did HIV originate and how did it infect the human race?

HIV is a lentivirus, and like all viruses of this type, it attacks the immune system. Lentiviruses are in turn part of a larger group of viruses known as retroviruses.

The name 'lentivirus' literally means 'slow virus' because they take such a long time to produce any adverse effects in the body. They have been found in a number of different animals, including cats, sheep, horses and cattle. However, the most interesting lentivirus in terms of the investigation into the origins of HIV is the Simian Immunodeficiency Virus (SIV) that affects monkeys.

In February 1999, a group of researchers from the University of Alabama announced that they had found a type of SIVcpz that was almost identical to HIV-1.This particular strain was identified in a frozen sample taken from a sub-group of chimpanzees known as Pan Troglodytes, which were once common in west-central Africa. They claimed that this sample proved that chimpanzees were the source of HIV-1, and that the virus had at some point crossed species from chimps to humans.

[edit] How could HIV have crossed species?

It has been known for a long time that certain viruses can pass between species. Indeed, the very fact that chimpanzee obtained SIV from two other species of ape shows just how easily this crossover can occur. As animals ourselves, we are just as susceptible. When a viral transfer between animals and humans takes place, it is known as zoonosis.

Below are some of the most common theories about how this 'zoonosis' took place, and how SIV became HIV in humans:

• The 'Hunter' Theory :

The most commonly accepted theory is that of the 'hunter'. In this scenario, SIVcpz was transferred to humans because of chimps being killed and eaten or their blood getting into cuts or wounds on the hunter. Normally the hunter's body would have fought off SIV, but on a few occasions it adapted itself within its new human host and become HIV-1. Every time it passed from a chimpanzee to a man, it would have developed in a slightly different way within his body, and thus produced a slightly different strain.

• The Oral Polio Vaccine (OPV) theory:

Some other rather controversial theories have contended that HIV was transferred iatrogenic ally (i.e. via medical experiments). One particularly well publicised idea is that polio vaccines played a role in the transfer. The final element that suggests that the OPV theory is not credible as the sole method of transmission is the argument that HIV existed in humans before the vaccine trials were ever carried out. More about when HIV came into being can be found below.

• The Contaminated Needle Theory:

This is an extension of the original 'hunter' theory. In the 1950s, the use of disposable plastic syringes became commonplace around the world as a cheap, sterile way to administer medicines. However, to African healthcare professionals working on inoculation and other medical programmes, the huge quantities of syringes needed would have been very costly. It is therefore likely that one single syringe would have been used to inject multiple patients without any sterilisation in between. This would rapidly have transferred any viral particles (within a hunter's blood for example) from one person to another, creating huge potential for the virus to mutate and replicate in each new individual it entered, even if the SIV within the original person infected had not yet converted to HIV.

• The Colonialism Theory:

The colonialism or 'Heart of Darkness' theory is one of the more recent theories to have entered into the debate. It is again based on the basic 'hunter' premise, but more thoroughly explains how this original infection could have lead to an epidemic. Jim Moore, an American specialist in primate behaviour, who published his findings in the journal, first proposed it in 2000 AIDS Research and Human Retroviruses.

During the late 19th and early 20th century, colonial forces ruled much of Africa. In areas such as French Equatorial Africa and the Belgian Congo, colonial rule was particularly harsh and many Africans were forced into labour camps where sanitation was poor, food was scare and physical demands were extreme. These factors alone would have been sufficient to create poor health in anyone, so SIV could easily have infiltrated the labour force and taken advantage of their weakened immune systems to become HIV. A stray and perhaps sick chimpanzee with SIV would have made a welcome extra source of food for the workers.

Moore also believes that many of the labourers would have been inoculated with unsterile needles against diseases such as smallpox (to keep them alive and working), and that many of the camps actively employed prostitutes to keep the workers happy, creating numerous possibilities for onward transmission. A large number of labourers would have died before they even developed the first symptoms of AIDS and those that did get sick would not have stood out as any different in an already disease-ridden population. Even if they had been identified, all evidence (including medical records) that the camps existed was destroyed to cover up the fact that a staggering 50% of the local population were wiped out there. One final factor Moore uses to support his theory is the fact that the labour camps were set up around the time that HIV was first believed to have passed into humans - the early part of the 20th century.

[edit] How is HIV transmitted?

A person who is HIV-infected carries the virus in certain body fluids, including blood, semen, vaginal secretions, and breast milk. The virus can be transmitted only if such HIV-infected fluids enter the bloodstream of another person. This kind of direct entry can occur (1) through the linings of the vagina, rectum, mouth, and the opening at the tip of the penis; (2) through intravenous injection with a syringe; or (3) through a break in the skin, such as a cut or sore. Usually, HIV is transmitted through:

Unprotected sexual intercourse (either vaginal or anal) with someone who is HIV infected.

Women are at greater risk of HIV infection through vaginal sex than men, although the virus can also be transmitted from women to men. Anal sex (whether male-male or male-female) poses a high risk mainly to the receptive partner, because the lining of the anus and rectum are extremely thin and filled with small blood vessels that can be easily injured during intercourse.

• Unprotected oral sex with someone who is HIV infected.

There are far fewer cases of HIV transmission attributed to oral sex than to either vaginal or anal intercourse, but oral-genital contact poses a clear risk of HIV-infection, particularly when ejaculation occurs in the mouth. This risk is increased when either partner has cuts or sores, such as those caused by sexually transmitted diseases (STDs), recent tooth-brushing, or canker sores, which can allow the virus to enter the bloodstream.

• Sharing needles or syringes with someone who is HIV infected.

Laboratory studies show that infectious HIV can survive in used needles for a month or more. That is why people who inject drugs should never reuse or share syringes, water, or drug preparation equipment. This includes needles or syringes used to inject illegal drugs such as heroin, as well as steroids. Other types of needles, such as those used for body piercing and tattoos, can also carry HIV.

• Infection during pregnancy, childbirth, or breast-feeding (mother-to-infant transmission).

Any woman who is pregnant or considering becoming pregnant and thinks she may have been exposed to HIV even if the exposure occurred years ago should seek testing and counselling. Mother-to-infant transmission has been reduced to just a few cases each year in the U.S., where pregnant women are tested for HIV, and those who test positive are provided with drugs to prevent transmission and counselled not to breast-feed.

[edit] How is HIV not transmitted?

HIV is not an easy virus to pass from one person to another.

• It is not transmitted through food or air (for instance, by coughing or sneezing).
• There has never been a case where a household member, relative, co-worker, or friend through casual or everyday contact such as sharing eating utensils and bathroom facilities, or hugging and kissing infected a person.
• Most scientists agree that while HIV transmission through deep or prolonged "French" kissing may be possible, it would be extremely unlikely.
• Sweat, tears, vomit, faeces, and urine do contain HIV, but have not been reported to transmit the disease (apart from two cases involving transmission from faeces via cut skin). Mosquitoes, fleas, and other insects do not transmit HIV.

[edit] Is there a cure for AIDS?

There is still no cure for AIDS. And while new drugs are helping many people with HIV/AIDS live longer, healthier lives, there are many problems associated with them:

• Anti-HIV drugs are highly toxic and can cause serious side effects, including heart damage, kidney failure, and osteoporosis.
• HIV mutates quickly. In as many as 50% of people on HAART, HIV mutates into new viral strains that have become highly resistant to current drugs, and as many as 10% of newly infected Americans are acquiring drug-resistant strains of the virus.
• Because treatment regimens are unpleasant and complex, many patients miss doses of their medication. Failure to take anti-HIV drugs on schedule and in the prescribed dosage encourages the development of new viral strains that are resistant to current HIV drugs.
• Even among those who do respond well to treatment, HAART does not eradicate HIV. The virus continues to replicate at low levels and often remains hidden in "reservoirs" in the body, such as the lymph nodes and brain.

[edit] Is there a vaccine to prevent HIV infection?

Despite continued intensive research, experts believe it will be at least a decade before we have a safe, effective, and affordable AIDS vaccine. Moreover, even after a vaccine is developed, it will take many years before the millions of people at risk of HIV infection worldwide can be immunized. Until then, other HIV prevention methods, such as using condoms and avoiding needle sharing, will remain essential.

[edit] Are there treatments for HIV/AIDS?

For many years, there were no effective treatments for AIDS. Today, people in the United States and other developed countries can use a number of drugs to treat HIV infection and AIDS. However, these don’t cure AIDS.

Some of these are designed to treat the opportunistic infections and illnesses that affect people with HIV/AIDS. In addition, several types of drugs seek to prevent HIV from reproducing and destroying the body's immune system:

• Reverse transcriptase inhibitors attack an HIV enzyme called reverse transcriptase. They include abacavir, delavirdine, didanosine (ddI), efavirenz, emtricitabine( FTC), lamivudine (3TC), nevirapine, stavudine (d4T), tenofovir, zalcitabine (ddC), and zidovudine (AZT);

• Protease inhibitors attack the HIV enzyme protease and include amprenavir, atazanavir, fosamprevavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir.

• Fusion inhibitors stop virus from entering cells. To date, there is only one fusion inhibitor approved by the Food and Drug Administration, Enfuvirtide. Many HIV patients take these drugs in combination in a regimen known as Highly Active Antiretroviral Therapy (HAART). When taken as directed, these drugs can reduce the level of HIV in the bloodstream to very low levels and enable the body's CD4 immune cells to rebound to normal levels.

Researchers are continuing to develop new drugs that act at critical steps in the life cycle of the virus. Efforts are also underway to identify new targets for anti-HIV medications and to discover ways of restoring the ability of damaged immune systems to defend against HIV and the many illnesses that affect people with HIV. Ultimately, advances in rebuilding the immune system in HIV patients will benefit people with a number of serious illnesses, including cancer, Alzheimer's disease, multiple sclerosis, and immune deficiencies associated with aging and premature birth.

[edit] What about Getting AIDS from Body Fluids like Saliva?

Although small amounts of HIV have been found in body fluids like saliva, faeces, urine, and tears, there is no evidence that HIV can spread through these body fluids.

By now, HIV has been the subject of more research than most other diseases in history. Medical science is confident about these basic facts: You can't get HIV or AIDS from touching someone, sharing items such as cups or pencils, or coughing or sneezing. HIV is not spread through routine contact in restaurants, workplaces, or schools.

[edit] What are the symptoms of AIDS?

The following may be warning signs of infection with HIV:

• Rapid weight loss
• Dry cough
• Recurring fever or profuse night sweats
• Profound and unexplained fatigue
• Swollen lymph glands in the armpits, groin, or neck, diarrhoea
• White spots or unusual blemishes on the tongue, in the mouth, or in the throat
• Pneumonia
• Red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
• Memory loss, depression, and other neurological disorders

However, no one should assume they are infected if they have any of these symptoms. Each of these symptoms can be related to other illnesses. Again, the only way to determine whether you are infected is to be tested for HIV infection.

[edit] Can I get infected with HIV from mosquitoes?

No, from the start of the HIV epidemic there has been concern about HIV transmission of the virus by biting and bloodsucking insects, such as mosquitoes. However, studies conducted by the CDC and elsewhere have shown no evidence of HIV transmission through mosquitoes or any other insects -- even in areas where there are many cases of AIDS and large populations of mosquitoes. Lack of such outbreaks, despite intense efforts to detect them, supports the conclusion that insects do not transmit HIV.

The results of experiments and observations of insect biting behaviour indicate that when an insect bites a person, it does not inject its own or a previously bitten person's or animal's blood into the next person bitten. Rather, it injects saliva, which acts as a lubricant so the insect can feed efficiently. Diseases such as yellow fever and malaria are transmitted through the saliva of specific species of mosquitoes. However, HIV lives for only a short time inside an insect and, unlike organisms that are transmitted via insect bites; HIV does not reproduce (and does not survive) in insects. Thus, even if the virus enters a mosquito or another insect, the insect does not become infected and cannot transmit HIV to the next human it bites.

There also is no reason to fear that a mosquito or other insect could transmit HIV from one person to another through HIV-infected blood left on its mouth parts. Several reasons help explain why this is so. First, infected people do not have constantly high levels of HIV in their blood streams. Second, insect mouth parts retain only very small amounts of blood on their surfaces. Finally, scientists who study insects have determined that biting insects normally do not travel from one person to the next immediately after ingesting blood. Rather, they fly to a resting place to digest the blood meal.

[edit] What about having a tattoo or your ears pierced?

Tattooing, ear piercing, acupuncture and some kinds of dental work all involve instruments that must be sterile to avoid infection. In general, you should refrain from any procedure where the skin is pierced, unless necessary.

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