Scientific American 60 Second Science听抄（有音频文件）

james.gumpUID: 2386126

KIND OF U:)

wenjingli123UID: 2396489

:handshake
3ks

idvisionUID: 2353686

:loveliness: 支持!

kevinliu6883UID: 2338522

A few years ago, scientists discovered a 3-foot skeleton of an early human species on the Indonesian island. They named the creature a "hobbit." But that find left scientists with two major questions: Do you sure 18,000-year-old bones represent an entirely new human species or it's just someone with growth disorder. Now the wrist bones may provide an answer. Researchers from the Smithsonian Institution published an article in the latest issue of Science. They showed that the hobbit's wrists are significantly different from both early humans and from Neanderthals. In fact, the wrists are close to those of African apes. Wrist bones take shape in early pregnancy and don't change much. They are also particularly distinctive between species. Scientists believe this shows that the early species in the human line migrate from Africa to Asia. They evolved into a new species on the Indonesian island. If modern humans and Neanderthals have a common ancestor, the modern humans and hobbits have a common, well, grand ancestor, making us and hobbits kind of second cousins.

kevinliu6883UID: 2338522

It's been a fun baseball season, but the storm club of steroids has hung over the game for years now, especially tarnished Barry Bonds' sort on the old time home run record. Tufts University physicist Roger Tobin is a big baseball fan and recently did some calculations to evaluate just how much impact steroids could actually have on power getting. When he crunched the numbers, he found the following: steroids might bring about 10% increase in muscle mass. That extra muscle could help batter swing 5% faster and that extra bat speed could cause the ball to jump off the bat 4% faster. Doesn't sound like much. However, if you add 4% in the initial velocity to the model distribution of trajectory of bat and baseballs, you can increase homers by a full 50%. Tobin's research will appear in the American Journal of Physics. He notes that weight lifting in smaller ballparks also play a role in pumping up the numbers of home runs. But the power searches in 90s go inside with steroids more than the other factors.

kevinliu6883UID: 2338522

For decades, dermatologists have said there’s no connection between diet and acne, but many patients have insisted they do see the link. Slowly information has been accumulated that chosen acne suffer may be right. A late study recently published in the Journal of American Academy of Dermatology. Australia researchers divided 54 young men with moderate acne into two groups. Half follow the typical western diet full of sugar and refined flour that is known high glycemic diet, the another half eat low glycemic diet, whole grains, vegetable and fish legume. After three months those with low glycemic diet have significantly fewer bright red bumps. Researchers see complex connection. Sugar and flour may inscelent bites. We know the incelent bites different levels of hormone, and hormone affect the development of acne. This hormone may not convince any teenage, but scientists said the diet-acne connection needs further research. Still, it is one study that favors of the diet influencing acting, and another against the typical American diet.

kevinliu6883UID: 2338522

The Carbohydrate Connection
For years, the common belief was diet had absolutely no effect on acne. Turns out, it may have been wrong.
A study completed by the Australia's RMIT University and Royal Melbourne Hospital Department of Dermatology have discovered what is being hailed as a "solid link" between diet and acne development.
Associate Professor Neil Mann, from RMIT University's School of Applied Sciences, led the research team which spent more than two years studying metabolic changes in glucose and insulin levels due to diet and the resulting changes on the skin.
Researchers believe carbohydrates with a high glycemic index, which cause glucose and insulin levels to spike, may influence the development and severity of acne.
Conversely, a diet high in protein and carbohydrates with a low glycemic index seemed to improve acne breakouts.
Professor Mann, along with Robyn Smith, PhD and Royal Melbourne Hospital, divided forty-three males, between the ages of 15 and 25, into two groups. One group was given foods with a low glycemic index, such as whole grain breads and pasta, legumes, as well as high protein foods. The second group was fed a more "typical" teenage diet consisting of white bread, potatoes, and sugary drinks and snacks.
The results, researchers say, were astounding. After 12 weeks, the boys in the high protein-low glycemic index group showed a fifty percent reduction of acne. The results seem to suggest a link between diet and acne development.
The results of the study were presented at the 15th Congress of the European Academy of Dermatology and Venerology, and have been published in the July 2007 issue of the American Journal of Clinical Nutrition, and the August 2007 issue of the Journal of the American Academy of Dermatology.
Dr. Mann, along with the Australian College of Dermatologists, has published a booklet, "The Teenage Anti-acne Diet," based on his research.
What This Means to You
Dr. Mann's study is intriguing, as it challenges the long-held beliefs regarding diet and acne. Interesting as the results are, they are preliminary and more research needs to be done.
So, is diet alone going to clear your acne? Probably not. However, a healthy diet will certainly improve your overall health. Instead of highly processed foods, try incorporating more whole grains (such as whole wheat bread, wheat pastas, brown rice, oatmeal, etc.) into your diet, as well as plenty of fresh vegetables, fruit, and lean protein. Limit the amount of soda, sugary snacks, and other "junk foods" whenever possible. You have nothing to lose, and a healthy body to gain. And possibly clearer skin, too.

kevinliu6883UID: 2338522

Bacterial to Animal Gene Transfers Now Shown to be Widespread, with Implications for Evolution and Control of Diseases and Pests

Scientists at the University of Rochester and the J. Craig Venter Institute have discovered a copy of the genome of a bacterial parasite residing inside the genome of its host species.

The research, reported in today's Science, also shows that lateral gene transfer—the movement of genes between unrelated species—may happen much more frequently between bacteria and multicellular organisms than scientists previously believed, posing dramatic implications for evolution.

Such large-scale heritable gene transfers may allow species to acquire new genes and functions extremely quickly, says Jack Werren, a principal investigator of the study. If such genes provide new abilities in species that cause or transmit disease, they could provide new targets for fighting these diseases.

The results also have serious repercussions for genome-sequencing projects. Bacterial DNA is routinely discarded when scientists are assembling invertebrate genomes, yet these genes may very well be part of the organism's genome, and might even be responsible for functioning traits.

"This study establishes the widespread occurrence and high frequency of a process that we would have dismissed as science fiction until just a few years ago," says W. Ford Doolittle, Canada Research Chair in Comparative Microbial Genomics at Dalhousie University, who is not connected to the study. "This is stunning evidence for increased frequency of gene transfer."

"It didn't seem possible at first," says Werren, professor of biology at the University of Rochester and a world-leading authority on the parasite, called wolbachia. "This parasite has implanted itself inside the cells of 70 percent of the world's invertebrates, coevolving with them. And now, we've found at least one species where the parasite's entire or nearly entire genome has been absorbed and integrated into the host's. The host's genes actually hold the coding information for a completely separate species."

Wolbachia may be the most prolific parasite in the world—a "pandemic," as Werren calls it. The bacterium invades a member of a species, most often an insect, and eventually makes its way into the host's eggs or sperm. Once there, the wolbachia is ensured passage to the next generation of its host, and any genetic exchanges between it and the host also are much more likely to be passed on.

Since wolbachia typically live within the reproductive organs of their hosts, Werren reasoned that gene exchanges between the two would frequently pass on to subsequent generations. Based on this and an earlier discovery of a wolbachia gene in a beetle by the Fukatsu team at the University of Tokyo, Japan, the researchers in Werren's lab and collaborators at J. Craig Venter Institute (JCVI) decided to systematically screen invertebrates. Julie Dunning-Hotopp at JCVI found evidence that some of the wolbachia genes seemed to be fused to the genes of the fruitfly, Drosophila ananassae, as if they were part of the same genome.

Michael Clark, a research associate at Rochester then brought a colony of ananassae into Werren's lab to look into the mystery. To isolate the fly's genome from the parasite's, Clark fed the flies a simple antibiotic, killing the Wolbachia. To confirm the ananassae flies were indeed cured of the wolbachia, Clark tested a few samples of DNA for the presence of several wolbachia genes.

To his dismay, he found them.

"For several months, I thought I was just failing," says Clark. "I kept administering antibiotics, but every single wolbachia gene I tested for was still there. I started thinking maybe the strain had grown antibiotic resistance. After months of this I finally went back and looked at the tissue again, and there was no wolbachia there at all."

Clark had cured the fly of the parasite, but a copy of the parasite's genome was still present in the fly's genome. Clark was able to see that wolbachia genes were present on the second chromosome of the insect.

Clark confirmed that the wolbachia genes are inherited like "normal" insect genes in the chromosomes, and Dunning-Hotopp showed that some of the genes are "transcribed" in uninfected flies, meaning that copies of the gene sequence are made in cells that could be used to make wolbachia proteins.

Werren doesn't believe that the wolbachia "intentionally" insert their genes into the hosts. Rather, it is a consequence of cells routinely repairing their damaged DNA. As cells go about their regular business, they can accidentally absorb bits of DNA into their nuclei, often sewing those foreign genes into their own DNA. But integrating an entire genome was definitely an unexpected find.

"The question is, are these foreign genes providing new functions for the host? This is something we need to figure out." Werren and Clark are now looking further into the huge insert found in the fruitfly, and whether it is providing a benefit. "The chance that a chunk of DNA of this magnitude is totally neutral, I think, is pretty small, so the implication is that it has imparted of some selective advantage to the host," says Werren. "The question is, are these foreign genes providing new functions for the host? This is something we need to figure out."

Evolutionary biologists will certainly take note of this discovery, but scientists conducting genome-sequencing projects around the world also may have to readjust their thinking.

Before this study, geneticists knew of examples where genes from a parasite had crossed into the host, but such an event was considered a rare anomaly except in very simple organisms. Bacterial DNA is very conspicuous in its structure, so if scientists sequencing a nematode genome, for example, come across bacterial DNA, they would likely discard it, reasonably assuming that it was merely contamination—perhaps a bit of bacteria in the gut of the animal, or on its skin.

But those genes may not be contamination. They may very well be in the host's own genome. This is exactly what happened with the original sequencing of the genome of the anannassae fruitfly—the huge wolbachia insert was discarded from the final assembly, despite the fact that it is part of the fly's genome.

In the early days of the Human Genome Project, some studies appeared to show bacterial DNA residing in our own genome, but those were shown indeed to be caused by contamination. Wolbachia is not known to infect any vertebrates such as humans.

"Such transfers have happened before in the distant past" notes Werren. "In our very own cells and those of nearly all plants and animals are mitochondria, special structures responsible for generating most of our cells' supply of chemical energy. These were once bacteria that lived inside cells, much like wolbachia does today. Mitochondria still retain their own, albeit tiny, DNA, and most of the genes moved into the nucleus in the very distant past. Like wolbachia, they have passively exchanged DNA with their host cells. It's possible wolbachia may follow in the path of mitochondria, eventually becoming a necessary and useful part of a cell.

"In a way, wolbachia could be the next mitochondria," says Werren. "A hundred million years from now, everyone may have a wolbachia organelle."

"Well, not us," he laughs. "We'll be long gone, but wolbachia will still be around."

This research was funded by the National Science Foundation's Frontiers in Integrative Biological Research program, which supports large, integrative projects addressing major questions in biology.

tangbaomingUID: 2363654

加油 我本来也想听这个 但是也没有找到文本 所以我现在听的是APNEWS

kevinliu6883UID: 2338522

Bacteria comes swatting gene even if two tiny creatures are only distantly related, for bacteria through some genes to multicell organisms is considered rare. When Bacteria gene were found in genomes, they are often thought to be due to contaminated samples, but a report in the latest issue of journal Science found that what’s called lateral gene transfer, may a time not be that usual. The bacteria were back instance, infect wide range of organisms, including about 20% olymsis species, and it presented ex cells that put good position to send gene to its host’s next generation. So researchers examine various host genomes to look for gene from backyard. They found 4 insects and 4 nematodes species whose gene included bacteria genes. That affect xxx subspecies practically xxx entirely minute. Such a lateral gene transfer maybe evolution kick start. A species instantly gets a package of new genes with new functions.

kevinliu6883UID: 2338522

It’s only a drill in a nuclear reactor. Such simulation trains operators to provide meltdowns. Such concern training make sure no repeat the disaster in Three Mile Island. But real problems still happened several times a month in 140 nuclear reactors in US. And plan to build as many as 29 new reactors that sound ever more common. A nuclear renoson on the way in the US bring government look for reliable secure and clear generate electricity. Reliable nuclear reactors can generate electricity nearly 90% of a time. Secure in such a power plant few found in Canada, Australia, and US. and climate friendly in generating electricity from uranium produce less green house gases and burning less fossil fuels, but questions remain including what to do with waste, in addition to be radioactive that contains material suitable for nuclear weapons. It remains to be same whether nuclear is bright and some say glowing hope or facet long. For a brand new energy, check sciam.com this week.

[ 本帖最后由 kevinliu6883 于 2007-9-29 12:56 编辑 ]

kevinliu6883UID: 2338522

New Jersey-based NRG Energy applies to build the first new nuclear power plant in the U.S. in more than 30 years
By David Biello
The two reactors at the South Texas nuclear power plant, an hour southwest of Houston, last year churned out 21.37 billion kilowatt-hours. By 2015, its majority owner, New Jersey-based NRG Energy, hopes to at least double that capacity if it gets permission to build two more reactors on the site. The company filed the first application on Monday for a new nuclear power plant—two advanced boiling-water reactors—in more than 30 years.
"It is a new day for energy in America," David Crane, NRG president and chief executive officer, said after making the application. "Advanced nuclear technology is the only currently viable large-scale alternative to traditional coal-fueled generation to produce none of the traditional air emissions," including the greenhouse gases responsible for climate change.
Armed with the backing of the White House and congressional leaders—and subsidies, such as $500 million in risk insurance from the U.S. Department of Energy— the nuclear industry is experiencing a revival in the U.S. As many as 29 new reactors may be added to the current U.S. fleet of 104, according to Bill Borchardt, director of the Nuclear Regulatory Commission's (NRC) office of new reactors. "It is going to be significantly different than it was in the 1970s," he says.
The South Texas project is the first entirely new reactor out of the gate, though it simply fulfills the original planning for four reactors at the site. The NRC says such upgrades of existing facilities are likely to comprise the majority of new nuclear power plants, all but one—a plant near Syracuse in central New York State— are in the Southeast or Texas. "At the majority of these sites, there's strong support for nuclear power," says Loren Plisco, NRC's deputy regional administrator for construction in the southeastern region.
The inactive reactor at Browns Ferry in northern Alabama was restarted in May after being shuttered for 22 years due to maintenance issues its owner, the Tennessee Valley Authority, decided would be too costly to fix. Completion of construction of a second reactor at TVA's Watts Bar power plant near Chattanooga in Tennessee has begun as well. The TVA expects to finish construction in 2013 at a cost of $2.49 billion. Its older twin at Watts Bar required 23 years to build at a total cost of nearly $7 billion, according to the TVA.
Such long delays and ballooning costs—paired with improvements in U.S. energy efficiency and reactor accidents at Three Mile Island in 1979 and Chernobyl in 1986—helped kill the first wave of nuclear power plant construction in the U.S. And the rebirth is not without controversy: Some environmentalists oppose the new construction, noting that all of the potential risks linked to nuclear power remain. "The flaws of nuclear power—excessive cost, security threats and long-lived radioactive waste—have not been solved," says Tyson Slocum, director of Public Citizen's energy program. "More nuclear reactors will only exacerbate these problems."
In fact, the only shift in the debate is the growing acceptance of nuclear power as an alternative energy source to coal-fired generation, which spews globe-warming greenhouse gas emissions. "If we're not serious about building more nuclear energy [power plants] around the world, then we are not serious about addressing climate change," James Rogers, chief executive of North Carolina based–Duke Energy, said during remarks at the recent U.N. climate summit.
Critics, such as Amory Lovins of the Rocky Mountain Institute, an energy think tank, counter that nuclear power is an overly complicated and dangerous solution to a relatively simple problem that cannot compete with safer, lower-emitting energy generation sources, such as wind, solar, geothermal, biomass, small hydropower and cogeneration, without government subsidies.
But proponents insist that if the U.S. and other countries continue to rely on large power plants and the demand for energy continues to grow as anticipated, then coal burning and uranium fissioning are the most effective options for boiling large amounts of water to produce steam to turn turbines—and thereby produce the most electricity.
The Intergovernmental Panel on Climate Change, an international body of scientists, economists and other experts, noted in a climate change report released earlier this year that "Nuclear energy … could make an increasing contribution to carbon-free electricity and heat in the future." But these experts only expect nuclear power to account for 18 percent of worldwide power generation in 2030 under emission-reduction scenarios, up from 16 percent today.
To reach even that slightly greater portion of world energy supply, however, will require the construction of at least 50 new nuclear power plants, not including replacements of existing reactors, in the next 23 years. NRG's application calls for the construction of two new reactors based on technology developed by General Electric and already operating in Japan and under construction in Taiwan. "We wanted a technology built by someone on time and on budget," Crane says. "There was only one design that satisfied that criteria and that was [the advanced boiling-water reactor.]"
The ABWR works by using the heat generated by the controlled splitting of uranium atoms in fuel rods to directly boil water into steam that then turns turbines to produce electricity. Improvements over previous designs include removing water circulation pipes that could rupture and accidentally drain water from the reactor, exposing the fuel rods to a potential meltdown, as well as fewer pumps to move the water through the system. "ABWR has digital primary controls [for the nuclear reactor] and analog backup. We think that's safer," notes Steve Winn, NRG's executive vice president for strategy, environment and nuclear development. "Planes are mostly digital by now but they also have fly-by-wire capability."
The new reactors will also have some modifications specific to the South Texas site, including floodproofing to protect the reactor from the adjacent 7,000-acre reservoir that provides its cooling water and updates to the pumps and fuel rods employed based on the Japanese experience of operating such reactors.
The company projects it will spend $6 billion constructing the two new reactors and hopes to have the first unit online by 2014, assuming the NRC completes its review by 2010. The NRC will first check to ensure the completeness of the voluminous application over the next two months, spokesman Scott Burnell says. "The staff's estimate is that the full technical review would take two and a half years," he adds.
The project, however, must overcome other hurdles, including a lack of technical and labor expertise as well as manufacturing capacity in the U.S., along with potential public opposition. "The stakes are high," Crane says, noting that the company has already spent $40 million on preparing the application and the price tag will be above $100 million when it orders the reactor vessel next year. "All it takes is one significant thing to go wrong and your project goes away." Nevertheless, the first step on the road to a nuclear revival in the U.S. has been taken.

wggmffUID: 2133909

0928

it's only a dread in a nuclear reactor. Such simulation treat operators the prevent malt downs. such concentrating has insured not repeat of the near disaster of 3 mile island. But real problem still have in 3 times a month for the 104 nuclear reactors in the US. And with plans to build as many as 29 new reactors that sound may become ever more common. A nuclear reneisance on the way in the US brought the government look for relaible, secure and climate friendly means of generating electricity. Reliable nuclear reactors can generate electricity nearly 90% of the time. secure of such power plants will lie on such fuel in Astralia, Canada, and the US. and climate friendly and generating electricity from Urinian products less green house gases than burning fossil fuels. But questions remain including what to do with the waste. In addition to be radiate reactive they contain material suitable for nuclear weapons. It remains to be same weather nuclear is blade, some might say growing hope with a fossil arm.
----------------------
a lot of mistakes.. han .>>>>>>>:funk:

airairappleUID: 2368189

坚持～我今天也开始练这个program。

liuyugogoUID: 2241890

不是每天都有啊，VOA也不错