Other News
World Population to Reach 9.1 Billion in 2050
The world's population will reach 6.5 billion by July and, despite lower expected fertility rates, is likely to reach 9.1 billion by 2050, with most of the increase taking place in developing countries, the United Nations Population Division says in its revised report for 2004.
In 2002 the Division had estimated a population in 2050 of 8.9 billion and last week, in a report sent to the 47-member UN Commission on Population and Development, had calculated the figure at 9 billion, reaching the 7 billion mark by 2012.
"World Population Change 1950-2050, the 2004 Revision" is the first of three volumes by the Division on global population trends.
"The world has added nearly 500 million people since 1999 - just six years," Hania Zlotnik, the new head of the Division, told a press briefing. "The good news is that new estimates show that it will take a little longer to add the next half billion, reaching the 7 billion mark probably by 2013."
Median fertility is expected decline from 2.6 children per woman today to slightly over 2 children per woman in 2050. If fertility were to remain about half a child above that level, world population would reach 10.6 billion by 2050, while fertility half a child below the median would lead to a population of 7.7 billion by mid-century.
Almost all of the increase will take place in the less developed countries, whose populations is expected to reach 7.8 billion in 2050 from 5.3 billion now, while the population of the more developed countries will remain around 1.2 billion, it says.
Between 2005 and 2050, eight countries - India, Pakistan, Nigeria, the Democratic Republic of the Congo (DRC), Bangladesh, Uganda, the United States, Ethiopia and China - are likely to contribute half of the world's population increase, while the population would at least triple in Afghanistan, Burkina Faso, Burundi, Chad, Congo, the DRC, Timor-Leste, Guinea-Bissau, Liberia, Mali, Niger and Uganda.
Fertility in the 44 developed countries remains generally low, with any increases being small, the report says.
In the 60 countries worst affected by HIV/AIDS, the impact of the disease is seen in increased morbidity and mortality and slower population growth, the report says.
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NASA'S Cassini Continues Making New Saturn Discoveries
NASA's Cassini spacecraft continues making new and exciting discoveries. The findings include wandering and rubble-pile moons; new and clumpy Saturn rings; splintering storms and a dynamic magnetosphere.
Weak, linear density waves caused in Saturn's rings by the small moons Atlas and Pan have yielded more reliable calculations of their masses. The masses imply the moons are very porous, perhaps constructed like rubble piles. They are similar to the moons that shepherd Saturn's F ring, Prometheus and Pandora.
Another discovery was a tiny moon, about three miles across, recently named Polydeuces. Polydeuces is a Trojan moon of Dione. They are found near gravitationally stable points, and Saturn is the only planet known to have moons with companion Trojan moons.
The new findings include refinements in the orbits of several of Saturn's small satellites. One intriguing result is the eccentric and slightly inclined orbit of Pan in Saturn's A ring. The orbit's shape is significant, as it indicates the type of interaction the moon has with the ring material surrounding it. If Pan's orbit remains eccentric due to this interaction, then planets growing in a disc of material surrounding a star may also have eccentric orbits. This may help explain the eccentric paths of planets orbiting other stars.
Several faint Saturn rings have been discovered in Cassini images. Some lie in various gaps in the rings and may indicate the presence of tiny embedded moons acting as shepherds. Several of the rings are kinked, likely evidence of nearby moons.
Scientists also found Saturn's winds change with altitude, and small storms emerge out of large ones. For the first time, Cassini images captured possible evidence of processes that may maintain the winds on Saturn. The observations offer a glimpse into the process which transfers energy by convection from Saturn's interior to help sustain strong winds.
Another surprising find was made by the ion and neutral mass spectrometer instrument, which measured molecular oxygen ions above Saturn's ring plane. The abundance of molecular oxygen on Earth is uniquely tied to biology. But these new measurements at Saturn suggest there are lifeless processes associated with cold icy surfaces that may produce an independent pathway for the formation of molecular oxygen in atmospheres. The findings were published in the journal Science.
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Galaxy of Dark Matter Discovered
A Cardiff University-led team of astronomers has discovered an object that appears to be an invisible galaxy made almost entirely of dark matter - the first ever detected. A dark galaxy is an area in the universe containing a large amount of mass that rotates like a galaxy, but contains no stars. Without any stars to give light, it could only be found using radio telescopes. It was first seen with the University of Manchester’s Lovell Telescope in Cheshire, and the sighting was confirmed with the Arecibo telescope in Puerto Rico. The unknown material that is thought to hold these galaxies together is known as ‘dark matter’, but scientists still know very little about what that is.
When astronomers observe the visible Universe it is like looking out at the darkest night from a well-lit room. It is easy to see the street lights, car headlights and other well-lit rooms, but not the trees, the hedges and the mountains because they don’t emit any light. We live on a planet close to a star, so as astronomers our observing 'room' is always well-lit. This can make it difficult to find the dark, hidden objects.
The international team from the UK, France, Italy and Australia has been searching for dark galaxies using not visible light, but radio waves. They have been studying the distribution of hydrogen atoms throughout the Universe. Hydrogen gas releases radiation that can be detected at radio wavelengths. In the Virgo cluster of galaxies they found a mass of hydrogen atoms a hundred million times the mass of the Sun. The Virgo cluster is a large group of galaxies about 50 million light years away.
Dr Robert Minchin from Cardiff University is one of the UK astronomers who discovered the mysterious galaxy, named VIRGOHI21. He explains, "From the speed it is spinning, we realised that VIRGOHI21 was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone. If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope."
Similar objects that have previously been discovered have since turned out to contain stars when studied with high-powered optical telescopes. Others have been found to be the remnants of two galaxies colliding. However, when the scientists studied the area in question using the Isaac Newton Telescope in La Palma, they found no visible trace of any stars, and no nearby galaxies that would suggest a collision. The astronomers first took observations of the dark object back in 2000 and it has taken almost five years to rule out all the other possible explanations. VIRGOHI21 appears to be the first dark galaxy ever detected.
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Primitive Brain is 'Smarter' Than We Think, MIT Study Shows
Primitive structures deep within the brain may have a far greater role in our high-level everyday thinking processes than previously believed, report researchers at the MIT Picower Center for Learning and Memory in the Feb. 24 issue of Nature.
The results of this study led by Earl K. Miller, associate director of the Picower Center at MIT, have implications about how we learn. The new knowledge also may lead to better understanding and treatment for autism and schizophrenia, which could result from an imbalance between primitive and more advanced brain systems.
Our brains have evolved a fast, reliable way to learn rules such as "stop at red" and "go at green." Dogma has it that the "big boss" lobes of the cerebral cortex, responsible for daily and long-term decision-making, learn the rules first and then transfer the knowledge to the more primitive, large forebrain region known as the basal ganglia, buried under the cortex.
Although both regions are known to be involved in learning rules that become automatic enough for us to follow without much thought, no one had ever determined each one's specific role.
In this study, Miller, who is the Picower Professor of Neuroscience, and postdoctoral associate Anitha Pasupathy found that in monkeys, the striatum (the input structure of the basal ganglia) showed more rapid change in the learning process than the more highly evolved prefrontal cortex. Their results suggest that the basal ganglia first identify the rule, and then "train" the prefrontal cortex, which absorbs the lesson more slowly.
The cortex--the "thinking" part of the brain - is highly developed in humans. This is especially true for the prefrontal cortex. Common wisdom suggests that when we learn new things, the prefrontal cortex figures things out first. Then, as our behaviors become familiar and habitual, the more primitive, subcortical basal ganglia take over so that the now-familiar routines can be run off automatically and occupy less of our thoughts.
"What we found was evidence for something very different," Pasupathy said. "We found that as monkeys learn new, simple rules--associations analogous to 'stop at red, go at green' - the striatum of the basal ganglia shows evidence of learning much sooner and faster than the prefrontal cortex. But, an interesting wrinkle is that the the monkeys' behavior improved at a slow rate, similar to that of the slower changes in prefrontal cortex."
This suggests that while the basal ganglia "learn" first, their output forces the prefrontal cortex to change, albeit at a slower rate.
The researchers speculate that perhaps the faster learning in the basal ganglia allows us (and our primitive ancestors who lacked a prefrontal cortex) to quickly pick up important information needed for survival. The prefrontal cortex then monitors what the basal ganglia have learned. Its slower, more deliberate learning mechanisms allow it to gather a more judicious "big picture" of what is going on by taking into account more history and thereby exert executive control over behavior, Miller said.
This work was supported by the National Institute of Neurological Disorders and Stroke and the Tourette's Syndrome Association.
