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| SCIENCE & TECHNOLOGY |
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Arctic suffers heatwave What killed the dinos
THIS UNIVERSE |
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Arctic suffers heatwave “This was exceptional for a place where the normal average temperatures are about 5 degrees C. This year we frequently recorded daytime temperatures of between 10 degrees C and 15 degrees C and on some days it went as high as 22C,” said Scott Lamoureux, a professor of geography at Queen’s. “Even temperatures of 15C are higher than we’d expect and yet we recorded them for between 10 and 12 days during July. We won’t know the August and September recordings until next year when we go back there but it appears the region has continued to be warm through the summer.” The high temperatures on the island caused catastrophic mudslides as the permafrost on hillsides melted, Professor Lamoureux said. “The landscape was being torn to pieces, literally before our eyes.” Other parts of the Arctic also experienced higher-than-normal temperatures, which indicate that the wider polar region may have experienced its hottest summer on record, according to Walt Meir of the US National Snow and Ice Data Centre in Colorado. “It’s been warm, with temperatures about 3C or 4C above normal for June, July and August, particularly to the north of Siberia where the temperatures have reached between 4C and 5C above average,” Dr Meir said. Unusually clear skies over the Arctic this summer have caused temperatures to rise. More sunlight has exacerbated the loss of sea ice, which fell to a record low of 4.28 million square kilometres (1.65 million square miles), some 39 per cent below the long-term average for the period 1979 to 2000. Dr Meir said: “While the decline of the ice started out fairly slowly in spring and early summer, it accelerated rapidly in July. By mid-August, we had already shattered all previous records for ice extent.” An international team of scientists on board the Polar Stern, a research ship operated by the Alfred Wegener Institute in Germany, also felt the effects of an exceptionally warm Arctic summer. The scientists had anticipated that large areas of the Arctic would be covered by ice with a thickness of about two metres, but found that it had thinned to just one metre. Instead of breaking through thicker ice at an expected speed of between 1 and 2 knots, the Polar Stern managed to cruise at 6 knots through thin ice and sometimes open water. “We are in the midst of a phase of dramatic change in the Arctic,” said Ursula Schauer, the chief scientist at the Alfred Wegener Institute, who was on board the Polar Stern expedition. “The ice cover of the North Polar Sea is dwindling, the ocean and the atmosphere are becoming steadily warmer, the ocean currents are changing,” she said. One scientist came back from the North Pole and reported that it was raining there, said David Carlson, the director of International Polar Year, the effort to highlight the climate issues of the Arctic and Antarctic. “It makes you wonder whether anyone has ever reported rain at the North Pole before.” — By arrangement with Independent, London |
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A collision 160 million years ago of two asteroids orbiting between Mars and Jupiter sent many big rock chunks hurtling toward Earth, including the one that zapped the dinosaurs, scientists said on Wednesday. Their research offered an explanation for the cause of one of the most momentous events in the history of life on Earth — a six-mile-wide (10-km-wide) meteorite striking Mexico’s Yucatan peninsula 65 million years ago. That catastrophe eliminated the dinosaurs, which had flourished for about 165 million years, and many other life forms, and paved the way for mammals to dominate the Earth and the eventual rise of humankind, many scientists believe. The impact is thought to have triggered a worldwide environmental cataclysm, expelling vast quantities of rock and dust into the sky, unleashing giant tsunamis, sparking global wildfires and leaving Earth shrouded in darkness for years. U.S. and Czech researchers used computer simulations to calculate that there was a 90 percent probability that the collision of two asteroids — one about 105 miles wide and one about 40 miles wide — was the event that precipitated the Earthly disaster. The collision occurred in the asteroid belt, a collection of big and small rocks orbiting the sun about 100 million miles from Earth, the researchers report in this week’s issue of the journal Nature.The asteroid Baptistina and rubble associated with it are thought to be leftovers, the scientists said. — Reuter |
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Wave adaptive vessel Pity the fisherman or sailor who staggers on deck in the morning and through bleary eyes sees a 100-foot-long water spider coming at him, buzzing ominously. No cause for alarm, however. It’s just Proteus, a so-called Wave Adaptive Modular Vessel designed for everything from military uses to biological studies, ocean exploration and sea rescue. Daniel Basta, director of the National Marine Sanctuaries for the National Oceanographic and Atmospheric Administration, said the lightweight, low cost and modular craft is well suited to scientific and environmental purposes.
—AP Incan mummy Museumgoers gasped Thursday at the well-preserved mummy of an Inca maiden which is on display for the first time, a serene gaze etched on her face hundreds of years ago when she froze to death in the Andes. Hundreds of people packed a museum in Salta, Argentina, to see “la Doncella” - Spanish for “the Maiden” - a 15-year-old girl whose remains were found in 1999 in an icy pit on Llullaillaco volcano, along with a six-year-old girl and a seven-year-old boy. Scientists believe the so-called Children of Llullaillaco were sacrificed more than 500 years ago in a ceremony marking the annual corn harvest. Dressed in fine clothes and given corn alcohol to put them to sleep, the victims were then left to die at an elevation of 22,080 feet. “Just this morning we have had more than 700 people come see the exhibit, and we had hundreds yesterday when it opened,” said High Mountain Archaeological Museum director Gabriel Miremont. The mummy is kept in a chamber that pumps chilled air through a low-oxygen atmosphere, simulating the subfreezing conditions where it was found. The other two children are being studied and not on display. –AP Ancient shipwrecks Cyprus is to launch sea surveys in an area where dozens of vessels led by warring successors to Alexander the Great are believed to have sunk in battle for control over the island in 306 BC. Encouraged by the discovery of one wreck from a later Roman era, the survey slated for the summer of 2008 will extend into deep waters from the south-east tip of the island, known as Cape Greco, the island’s Antiquities Department said. “Cyprus is a crossroads and is very rich in ancient shipwrecks,” said Pavlos Flourentzos, director of Cyprus’s Department of Antiquities. Historical accounts suggest that the Cape Greco region — a rocky outcrop between the now popular tourist resorts of Agia Napa and Protaras, saw one of the biggest naval battles of the ancient world.
— Reuter |
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We have solid, liquid, gas and plasma states of matter. In which of these can we include fire? Consider this. We take a solid and start heating. This increases the vibration of the molecules of the solid. At some point their vibration energy overcomes the bonds of the lattice and the solid turns into a liquid. Molecules in the liquid are not completely free; they are still subject to intermolecular forces. We go on heating to the point where the thermal energy of the molecules allows them to escape the shackles of their neighbours. Then we have a gas. If we go on heating this gas we may come to a point where the energy of collision of the molecules is high enough to break up the atoms. In other words electrons can be knocked out of the atoms. This is a state where the overall charge of the gas is still zero but the gas is made up of positive and negative particles. Such a gas becomes a highly conducting medium. It would be all right to call this state as a plasma state. In this state electricity is easily conducted. Movement of charged particles produces magnetic fields. Coupling between currents and magnetic fields is central. If the plasma is propelled in a certain direction the entangled magnetic fields travel along with it. This is the phenomenon that is encountered when streams of solar plasma travel out during solar activity. When this plasma, along with its frozen magnetic fields hits the magnetosphere of the earth we experience problems in radio communication and magnetic storms. A familiar example of plasma is encountered in the fluorescent tubes that all of us use in our homes. The current in the tube is sustained by plasma. The interactions produce high frequency radiation, mostly in ultra violet, which when falling over the fluorescent material of the walls of the tube produces visible light. At this point you might think that I am dodging you question “in what state of matter can we include fire”. Fire is not a thing but a happening. It is a happening in which high temperature does produce ionized particles that emit light during recombination. In that sense there is plasma in fire. But its flame and dance are due to turbulent convection in which air rushes in from out side, helps sustain the combustion in which energy is produced, rising gases include plasma and neutral gases. Fire would look rather different in a gravity free atmosphere. In short fire does contain some plasma along with other gases, besides the happening of a reaction in which energy is produced. The sun produces heat, but the moon does not. What is the reason? Amongst the heavenly bodies only the big ones produce energy. The Moon is not big enough to be a star. The Sun is. Mercury, Venus, the Earth, Mars, Jupiter and Saturn, indeed none of the planets generate significant amounts of energy. They are not stars. They get their energy mainly from the Sun, which is the only star of our family. All the planets and the moon shine because of the light they receive from the sun. They just scatter some of the light they receive. Why does an object have to big enough to become a star? We now understand this reasonably well. Heavenly bodies are not born big. They become so by a lot of matter falling together over a long period of time due to the force of gravity. This falling together leads to collisions and ultimately chaotic motions of atoms and molecules. This chaotic motion is nothing but heat. The inner temperature of the large body can rise to millions of degrees. When that happens, the energy of individual particles is such that nuclear reactions can commence. There is much more to this story and we can get to that if there is interest. For the time being it is enough to say that our Sun was big enough for such nuclear reactions to commence. Indeed the light, heat and energy that we get from the sun is actually the nuclear energy being produced in the Centre of the sun. None of the other planets made it to the starting line. Just as well because life would have been very different and difficult with two Suns around. Why do fruits and flowers lose fragrance when we keep them in our fridge? I congratulate you for discovering this question. I am using the word discovering because it did not occur to me till now. It is quite possible that lot of people have already discovered it and most of them even know the answer. The extent to which we become used to accepting the world without ever asking why is truly amazing. I will try guessing the answer to your query. There might be some other considerations that come in. If you think of something let me know. I will also think a little more about it. We smell things because actual molecules travel out and reach the receptors in our nose. These receptors are like locks that accept only specific keys. They are very particular. When a reception occurs a signal travels out to our brain giving us the feeling of a specific smell. There are a thousand or more types of receptors, each giving a slightly different sense of smell. In addition there might be smell we sense through combinations of different sets of receptors firing. Let me not go on talking about this amazing capability we have to enjoy this world and return to your question. Now the basic answer is easy. Molecules can diffuse out if they belong to a material that is volatile — like alcohol or petrol that evaporate away even at room temperature. The number of molecules coming out would depend on the vapour pressure. Vapour pressure — or rate of evaporation — increases with temperature. (We know this because we can dry our wet clothes faster if we hang them out in the sun). So at low temperature the volatiles of the fruit or the flower would come out at a lower rate. Smell is nothing but sensing of volatiles. Hence it would be reduced if the fruit or the flower were cold. |
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