Frontline Magazine October 2011 | Online Notes

Adaptive Optics
Twinkling of stars is because of the swirling air or the turbulence in the atmosphere above us. The same thing happens when stars or planets are observed or imaged through a telescope. Adaptive Optics is a technique that uses optical systems in conjunction with the telescope to correct, or compensate for, the optical aberrations introduced by the intervening medium. Laser guide star and Rayleigh beacon are AOs, used in large telescopes. The latest Project Robo-AO's aim was to demonstrate a low-cost autonomous LGS AO system and science instrument, which works both in the visible and near-infrared, and is specifically designed to take advantage of modest aperture telescopes by improving their sensitivity. 
Beyond Time
Ghazal maestro Jagjit Singh passed away this month. "Beyond Time" is the biograpy of Jagjit Singh. 

Innate and Adaptive Immunity
TO defend themselves against infection by external microorganisms such as bacteria, viruses, fungi and parasites, living beings possess layers of defence with increasing specificity. The first layer is the physical block such as skin and external secretions that prevents microorganisms from entering the body. If it fails, we have innate immunity, present in all plants and animals, which can counter their attack and destroy invading pathogens. If the innate response is unable to counter the invading organism, the second layer of the immune system, called the “adaptive” or “acquired” immune system, takes over. Adaptive immunity produces antibodies that fight the infection and killer cells that destroy infected cells. The adaptive immune system is, however, known to be present only in jawed vertebrates. This year's Nobel Prize for Physiology or Medicine has gone to three scientists who unravelled the key mechanisms underlying the activation of the immune system, both innate and adaptive. One half of the prize has gone to Jules Hoffman and Bruce Beutler “for their discoveries concerning the activation of innate immunity” and the other half to Ralph Steinman “for his discovery of the dendritic cell and its role in adaptive immunity”.

Dendritic cells
Dendritic cells are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system. That is, dendritic cells function as antigen-presenting cells. They act as messengers between the innate and adaptive immunity. Dendritic cells are present in tissues in contact with the external environment, such as the skin (where there is a specialized dendritic cell type called Langerhans cells) and the inner lining of the nose, lungs, stomach and intestines. They can also be found in an immature state in the blood. Once activated, they migrate to the lymph nodes where they interact with T cells and B cells to initiate and shape the adaptive immune response.

International Year of Chemistry - celebration by Vigyan Prasar
Godmen and saints propagate the magic of chemical reactions that nature itself has encoded. Dry coconut burns when water is poured over it because of the sodium kept hidden in it. Ash is produced when fingers dipped in mercuric chloride solution are rubbed against an aluminium coin. This is then passed off as divine ash, or vibhuti, to the devotee. In an underdeveloped and semi-literate society like India's, scientific explanations of such miracles are unpopular. It is this mindset that Vigyan Prasar, under the Department of Science and Technology of the Government of India, has been trying to change for the past 22 years. The year 2011 marks the International Year of Chemistry, and therefore, Vigyan Prasar has been encouraging experiments that denounce miracles. This it does by conducting workshops among chemistry teachers and through its literature and voluntary science clubs across the country. 

Credit Default Swaps
A credit default swap (CDS) is similar to a traditional insurance policy, here the seller of the CDS obliges to compensate the buyer in the event of loan default. Generally, the agreement is that in the event of default the buyer of the CDS receives money (usually the face value of the loan), and the seller of the CDS receives the defaulted loan (and with it the right to recover the loan at some later time).Currently European Banks are buying CDS to hedge their funds. 

Operation Enduring Freedom - 10 years of Afghan invasion
George W. Bush administration launched its “Operation Enduring Freedom” in 2001 to show “the oppressed people of Afghanistan… the generosity of America”.  The United Nations has said that more than 10,000 civilians were killed in the past five years alone. More than 2,500 soldiers, most of them Americans, have also perished in Afghanistan in the past 10 years. The U.S. is estimated to have spent more than $500 billion so far on its war effort in Afghanistan. Every day, Washington spends $2 billion for the upkeep of its soldiers in Afghanistan at a time when the American public has got deeply disillusioned about the war. 

Bangladesh - Trail on liberation war of 1971 begins
ON October 3, Delwar Hossain Sayedee, a firebrand leader of the fundamentalist Jamaat-e-Islami, became the first suspect to be formally charged by the International Crimes Tribunal (ICT), which is probing the charges of rape, genocide and other crimes against humanity committed during the liberation war of 1971. The tribunal was constituted by the Sheikh Hasina government on March 25, 2010, to try those Bangladeshis (then East Pakistanis) accused of collaborating with the Pakistan army and committing atrocities. With the opening of the war crimes trial, 18 months after the formation of the tribunal and four decades after the historic war, the Hasina government has virtually reopened the country's independence history. Horrendous crimes were committed during the nine-month-long war, which resulted in the secession of East Pakistan from Pakistan. Some three million people were killed, nearly half a million women were raped and over 10 million people were forced to flee to India to escape brutal persecution at home.