HIV

Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immudefiency syndrome (AIDS), a condition in humans in which the imunne system begins to fail, leading to life-threatening opportunistic infection. Infection with HIV occurs by the transfer of blood,semen, vaginal fluid, pre-ejaculate, or breast milk. Within theese bodily fluids, HIV is present as both free virus particles and virus within infected imunne cells. The four major routes of transmission are unsafe sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth (vertical transmission). Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.

HIV infection in humans is considered pandemic by WHO. From 1981 to 2006, AIDS killed more than 25 million people. HIV infects about 0.6% of the world's population. In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. A third of these deaths are occurring in sub saharan,Africa, retarding economic growth nd increasing poverty. According to current estimates, HIV is set to infect 90 million people in africa, resulting in a minimum estimate of 18 million orphan. Antriretvorial treatment reduces both the mortality and the morbodity of HIV infection, but routine access to antiretroviral medication is not available in all countries.

HIV primarily infects vital cells in the humman immune systemsuch as Helper T cells (specifialy cd4⁺ T cells), Marchopages, and Dendritic cells. HIV infection leads to low levels of CD4⁺ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4⁺ T cells by lymphocites that recognize infected cells. When CD4⁺ T cell numbers decline below a critical level, cell-immediate system is lost, and the body becomes progressively more susceptible to opportunistic infections.

Eventually most HIV-infected individuals develop AIDS. These individuals mostly die from opportunistic infections or malignancies associated with the progressive failure of the immune system. Without treatment, about 9 out of every 10 persons with HIV will progress to AIDS after 10–15 years. Many progress much sooner.Treatment with anti-retrovirals increases the life expectancy of people infected with HIV. Even after HIV has progressed to diagnosable AIDS, the average survival time with antiretroviral therapy (as of 2005) is estimated to be more than 5 years. Without antiretroviral therapy, death normally occurs within a year.

Structure Of HIV

The Bermuda Triangle, also known as the Devil's Triangle, is a region in the western part of the North Atlantic Ocean in which a number of Air Craft and Surface vessel are alleged to have disappeared in mysterious circumstances which cannot be explained as Human Error, pirracy, equipment failure, or natural disaster. Popular culture has attributed some of these disappearances to the paranormal, a suspension of te law physyc, or activity by extraterestrial terres .

A substantial body of documentation reveals, however, that a substantial portion of the allegedly mysterious incidents in the Bermuda Triange have been inaccurately reported or embellished by later authors, and numerous official agencies have stated that the number and nature of disappearances in the region is similar to any other area of ocean .

- The Triangle Area :

The boundaries of the triangle cover the strais of Florida, the Bahamas and the entire Carribean island area and the Atlantic east to the Azores ; others add to it the Gulf Of Mexico. The more familiar triangular boundary in most written works has as its points somewhere on the Atlantic coast of Miami, San Juan, Puerto Rico ; and the mid-Atlantic island of Bermuda, with most of the accidents concentrated along the southern boundary around the Bahamas and the Florida Straits.

The area is one of the most heavily-sailed shipping lanes in the world, with ships crossing through it daily for ports in the Americas, Europe , and the Caribbean Islands. Cruise ships are also plentiful, and pleasure craft regularly go back and forth between Florida and the islands. It is also a heavily flown route for commercial and private aircraft heading towards Florida, the Caribbean, and South America from points north.

Red Giant Star

A red giant is a luminous giant star of low or intermediate mass (roughly 0.5–10 solar masses ) that is in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the spectral types K and M, but also class S stars and most carbon stars.

The most common red giants are the so-called red giant branch stars (RGB stars) whose shells are stillinto helium, while the core is inactive helium. Another case of red giants are the asymptotic giant branch stars (AGB) that produces carbon from helium by the triple alpha process. To the AGB stars belong the carbon stars of type C-N and late C-R.

Prominent bright red giants in the night sky include Aldebaran (Alpha Tauri), Acturus (Alpha Bootis), and Gamma Crucis (Gacrux), while the even larger Antares (Alpha Scorpii) and Betelgeuse (Alpha Orionis) are red super giant.

Picture Of Red Giant

Supernova

A supernova is a stellar explosion . Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the suncould emit over its life span. The explosion expels much or all of a star's material. at a velocity of up to 30,000 km/s (a tenth the speed of light , driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.

Several kinds of supernovae exist that may be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an agging massive star ceases to generate energy from nuclear fusion, it may undergo sudden gravitation collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers. Alternatively, a whita drev star may accumulate sufficient material from a (usually through accretion, rarely via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes run away nuclear fusion, completely disrupting it. Stellar cores whose furnaces have permanently gone out collapse when their masses exceed the chandra sekhar limit, while accreting white dwarfs ignite as they approach this limit (roughly 1.38. times the mass of the sun). White dwarfs are also subject to a different, much smaller type of thermonuclear explosion fueled by hydrogen on their surfaces called a nova. Solitary stars with a mass below approximately nine solar masses, such as the Sun itself, evolve into white dwarfs without ever becoming supernovae.

Picture Of Supernova