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Coral reefs could be destroyed What drives millions to social networking sites Prof Yash
Pal THIS UNIVERSE
Trends |
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Coral reefs could be destroyed All of the tropical coral reefs in the world will be disintegrating by the end of the century because of the rising acidity of the oceans caused by a Coral reefs start to disintegrate when the acidity of the oceans rises beyond a certain threshold, and this point is likely to be reached before 2100, said Jacob Silverman of the Carnegie Institution of Science in Washington. Carbon dioxide in the air dissolves in the sea to form carbonic acid, which interferes with the ability of coral organisms to make their calcium carbonate shells which form coral reefs, Dr Silversman, said. But once the shells stop forming, the reef quickly crumbles. A mathematical model was used to study how 9,000 coral reefs from around the world would respond to rising levels of carbon dioxide and increasing ocean acidity, Dr Silverman told the American Association for the Advancement of Science in San Diego. “A global map produced on the basis of these calculations shows that all coral reefs are expected to stop their growth and start to disintegrate when atmosphere CO2 reaches 560 parts per million - double its pre-industrial level - which is expected by the end of the 21st-century,” he told the meeting. “Thus these ecosystems, which harbour the highest diversity of marine life in the oceans, may be severely reduced within less than 100 years.” The findings were based on a detailed study of how increasing acidity affects the metabolism and growth of a large area of fringing coral reef in the northern Red Sea. The scientists found that the ability of corals to form their calcium skeletons was strongly dependent on acidity and, to a lesser extent, temperature. Coral reefs are sometimes considered to be the “rainforests of the oceans” because they are home to a wide variety of fish and other wildlife, supporting about a quarter of all marine organisms. They also provide food for about 500 million people around the world. Atmospheric levels of carbon dioxide are higher now than at any time in the last 650,000 years, and are continuing to rise as a result of the burning of fossil fuels. Between a third and a half of the CO2 produced since the start of the industrial revolution has dissolved in the oceans. Scientists have estimated that some 118 billion tonnes of carbon released into the air as carbon dioxide between 1800 and 1994 has been taken up by the oceans. Dr Simon Donner, of the University of British Columbia in Canada, said increasing ocean temperatures also make coral reefs more susceptible to “bleaching”, caused by the loss of the photosynthetic algae on which the coral organisms depend. Corals have a symbiotic relationship with the microscopic algae that live in their tissues. As well as giving coral its vibrant colour, the algae provide the reef creatures with most of their energy. Dr Donner said: “Even if we froze emissions today, the planet still has some warming left in it. That's enough to make bleaching dangerously frequent in reefs worldwide.” —By arrangement with
The Independent |
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What drives millions to social networking sites Curiosity to know about other people's lives and self-expression drive millions of people to online networking sites like the Facebook, MySpace and Twitter. Research on social network sites has focused largely on user personality traits, benefits to individuals such as information sharing, issues of privacy and the like. Now, Macquarie University doctoral student in marketing, Lucy Miller, is taking a closer look at online social networks from a marketing perspective. These give the sites' owners and potential advertisers insights into their users thoughts and patterns of behaviour. Miller found four key motivating factors influencing users. These were curiosity about the lives of others, social engagement, a desire to increase social capital and status, and self-expression. Users driven by curiosity were less likely to contribute much in the way of content but would likely have a higher tolerance for advertising, Miller found. Similarly, others had a need to express themselves and would not be as active in seeking friends, instead feeling more satisfied that the site allowed them to be creative and reduce their anxieties. Still yet others built social capital and status through the large network of friends they established. Based on her preliminary survey, Miller argues that those differing core motivational profiles and resulting behaviours show social networking sites such as Facebook have distinctly segmented user markets. Site owners, anxious to retain and increase user numbers, and advertisers wanting to reach those user-consumers, need to be aware of the differences and tailor their approaches accordingly, she said. Miller also found other less clear factors such as gender and major transitional events in life such as a divorce, death, moving house or changing jobs can also influence and create changes in user behaviours, said a Macquarie release. She recently presented her preliminary research at the Australian and New Zealand Marketing Academy conference in Melbourne.
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THIS UNIVERSE When we boil milk on direct flame in a vessel it tends to rise fast and spills out when boiling begins. However, milk can also be heated in a pot that is placed in another vessel in which water is being heated to boiling point. It has been found that in this case milk can be boiled but it does not rise up and overflow. Please explain the reason for this difference. I have got this or similar question several times. I gave this answer six years ago. Milk is not a simple liquid. It contains lot of things. It contains tiny globules of fat and casein (stuff that is found in cheese). They are not dissolved in water—they are suspended. On heating there is separation of constituents. Some of the stuff, such as cream, floats up. Some of it on the surface sticks to the sides of the vessel. After a while a membrane-like film begins to form on the surface, containing cream and casein. When the boiling starts all the energy of the burner is used in converting water into steam. The pressure below the membranes suddenly increases and the rising bubbles of steam make the milk overflow and spill out. In the interesting alternative of heating milk that you have suggested there is no extra input of heat for causing vigorous conversion of water into steam after the milk has reached the point of boiling; the temperature around the vessel is the same even when the water in the outer vessel is boiling. This must be the reason for graceful residence of milk close to boiling point. Readers wanting to ask Prof Yash Pal a
question can e-mail him at palyash.pal@gmail.com |
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Trends NUSA DUA, Indonesia: Emission cuts pledges made by 60 countries will not be enough to keep the average global temperature rise at 2 degrees Celsius or less, modeling released on Tuesday by the United Nations says. Scientists say temperatures should be limited to a rise of no more than 2 degrees Celsius (3.6 F) above pre-industrial times if devastating climate change is to be avoided.
Space shuttle fleet's 130th mission
CAPE CANAVERAL, Florida: Space shuttle Endeavour and its six crew members wrapped up a 14-day construction mission to the International Space Station on Sunday with a precision touchdown in Florida. After 217 orbits around Earth and 5.7 million miles (9.17 million km), commander George Zamka circled Endeavour high over the Kennedy Space Center to burn off speed, then nosed the 100-ton ship onto a canal-lined runway at 10:20 p.m. EST.
Flightless mosquitoes may curb dengue
WASHINGTON: Genetically altered mosquitoes that cannot fly may help slow the spread of dengue fever and could be a harmless alternative to chemical insecticides, U.S. and British scientists said on Monday. They genetically altered mosquitoes to produce flightless females, and said spreading these defective mosquitoes could suppress native, disease-spreading mosquitoes within six to nine months.
Indian Ocean clues to predicting El Nino
HONG KONG: Tracking Indian Ocean climate patterns could improve early-warning systems for the El Nino phenomenon, helping save lives and billions of dollars lost each year to the severe weather it causes. In a paper published in Nature Geoscience, researchers in Japan and France said their new forecast model could predict an El Nino 14 months ahead of time, several months earlier than with current methods.
Egypt to get back coffin smuggled in 1884
CAIRO: A 3,000-year-old painted coffin smuggled out of Egypt more than a century ago will be returned after U.S. customs inspectors intercepted it in transit, Egypt's culture ministry said on Monday. The coffin, described as one of the “most beautiful plastered and painted” pieces found in Egypt, was seized by customs officials upon its arrival at a Florida airport in October 2008, the ministry said in a statement.
Losing Google would hit Chinese science
LONDON: More than three-quarters of scientists in China use the search engine Google as a primary research tool and say their work would be significantly hampered if they were to lose it, a survey showed on Wednesday. Google's future in the country is uncertain following a row with Beijing, but Chinese scientists asked by the Nature journal how much they rely on Google said it was vital for finding academic papers, information about discoveries or other research programs and finding scholarly literature. —
Reuters
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