VOA标准英语2010年-Our World — 29 January 2010（在线收听）

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This week on Our World: ... A new role for a Mars rover ... how a genetic map of flesh-eating bacteria could help kids with heart-damaging rheumatic fever ... and green cars at the Washington Auto Show.

COGAN:  "We're seeing electrification in a big way. We're seeing more advanced clean-diesel vehicles that get high fuel efficiency and advanced gasoline internal combustion. I think innovative answers in general – that's what we're seeing here in Washington."

Those stories, a new dinosaur discovery, and more...

I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."

Mars Rover Loses Mobility, Takes on New Science Role

In 2004, the U.S. space agency NASA landed two spacecraft on Mars.

Spirit and Opportunity were the names given to two radio-controlled mobile research platforms designed to drive around the Martian surface, taking pictures and collecting scientific data.

Their mission was supposed to last 90 days.

Six years later, Opportunity is still on the job, but 10 months ago Spirit got stuck in the Martian dirt and hasn't been able to free itself.

So this week, NASA officials conceded defeat and reclassified Spirit from Martian rover to stationary research platform.

The top rover scientist, Steve Squyres of Cornell University, told reporters their new plan is to use the rover as a radio beacon, to enable scientists to very accurately track the rover's motion through space. Since Spirit is just sitting in one place on Mars, that means you're actually tracking the location of that one spot on the Martian surface. And while the orbit of Mars around the sun is very well understood, the rotation of the planet is a bit more complex.

SQUYRES:  "Mars spins on its axis, and it turns out that because of gravitational interactions with the sun, with the moons of mars, Mars's spin axis wobbles, ever so slightly. And so if we can track the motion of the rover very precisely and watch Mars spin, we can characterize very precisely the nature of that wobble."

Squyres says that the wobble could be a key that might unlock secrets of the interior of Mars, including whether the core at the center of the planet is solid or liquid.

SQUYRES:  "Totally new science, never been done before, really fundamental stuff. This is something that I didn't really think much about when we first put a rover on the surface of Mars, because we were thinking about the geology of the surface. But when you delve deeply into what this vehicle is capable of, you find new tricks. And this is one that we're extremely excited about."

The twin rovers have sent back some astonishing pictures of the Martian landscape over the past six years, taken at close range, right there at ground level on the Martian surface. You can see them at the NASA website, or we'll have a direct link on our site, voanews.com/ourworld.
 

Stomach Bug May Fight TB

Tuberculosis is an infectious disease that usually attacks the lungs, and if left untreated, it kills more than half of its victims. Now, a new way to fight TB has been discovered in the most unlikely place – your stomach. Jim Hawk has the story.

HAWK:  TB is the world's second deadliest contagious disease, after HIV/AIDS, killing some 1.8 million people each year. The World Health Organization estimates one-third of the world's population has a latent TB infection – the bacteria is present in their lungs, but isn't making them sick.

It's estimated that one-half to two-thirds of the world is infected with H. pylori. While this bacteria weakens the stomach lining and can cause ulcers and gastric cancer, most people have no symptoms.

A group of researchers found a relationship between the two bacteria.

SOLNICK:  "People that are exposed to tuberculosis who have H. pylori infection are less likely to get active disease than are those that don't have pylori infection."

HAWK:  Jay Solnick of the University of California Davis is the principal investigator and co-author of the study.. He says having H. pylori seems to prompt the body's immune response.

SOLNICK:  "People that are pylori positive have higher interferon gamma responses to tuberculin antigens than do those that are pylori negative, and interferon gamma is thought to be protective against tuberculosis."

HAWK:  More evidence of the protective effect of H. pylori came from researcher Sharon Perry, an epidemiologist at Stanford University and the study's lead author, who looked at follow-up studies on family members of TB victims in Gambia and Pakistan. Both are countries in which virtually everyone is thought to be infected with H. Pylori.

PERRY:  "We were astounded when we discovered that the individuals who had active TB had far lower prevalence of H. pylori infection than did the household contacts who did not develop active tuberculosis."

HAWK:  While this new study makes the connection between the common stomach pathogen and protection against tuberculosis, more research is needed to offer definitive proof, and better understand how H. pylori provides that benefit. Jay Solnick says the ultimate goal is to harness H. pylori to make TB vaccines more effective. The research article appears online in PLoS ONE, a peer-reviewed scientific journal from the Public Library of Science.

I'm Jim Hawk.

Researchers Seek Genetic Clues to Deadly Bacterial Epidemics

"Flesh-eating bacteria" sounds like the menace from a low-budget horror movie. But the horror is very real when group A streptococcus runs amok. Strep-A is normally a harmless sore throat bug that sometimes can spawn an epidemic of skin destruction.

An international team of researchers looking for the cause of those epidemics has now deciphered the strep-A genome. And as we hear from VOA's Jessica Berman, the breakthrough could also speed the development of a vaccine to prevent the leading cause of heart disease in children.

BERMAN:  The scientists mapped the genetic material of nearly 100 samples of strep-A bacteria involved in three severe epidemics in Ontario, Canada, during the past 17 years.

The focus of their interest was strep A's ability to transform itself from a relatively benign microbe into a potent pathogen responsible for the lethal disease known as necrotizing fasciitis, which causes widespread skin destruction. It can also lead to a deadly blood infection, according to Jim Musser, co-director of the Methodist Research Institute in Houston, Texas.

Musser says patients may be extremely sick before seeking medical help because severe strep-A infections may at first mimic other milder diseases like the flu. Musser says lethal forms of strep-A often go undetected by physicians because such infections occur infrequently and many doctors fail to recognize them.

MUSSER:  "Many of these patients show up at their doctor or the hospital too late in the course of their disease to be adequately treated. The disease has progressed too far to be able to really save the patient."

BERMAN:  Musser led the team of researchers that deciphered the genetic make-up of bacteria responsible for three successive epidemics in Canada, hoping to learn the molecular underpinnings of the bacteria.

MUSSER:  "This has permitted us for the first time to have a precise molecular portrait of how the organisms change over this time, which organisms have the propensity to cause a more severe type of illness, and the exact molecular changes in the pathogen that are responsible."

BERMAN:  Musser says having the bacterial genome helps researchers understand how the flesh-eating pathogen takes advantage of people who become infected with it, so better diagnostics and treatments can be developed.

Musser is hopeful the work also leads to the development of a vaccine against group-A streptococcus to prevent rheumatic fever, the leading cause of childhood heart disease in developing countries, where poverty is widespread. Strep A causes inflammation of the heart muscle and damages the internal valves.

According to the World Health Organization, the infection is responsible for more than three million cardiovascular deaths each year.

BERMAN:  An article on the genetics of aggressive streptococcus, by Methodist University's Jim Musser and colleagues, is published this week in Proceedings of the National Academy of Sciences.

Jessica Berman, VOA News, Washington.

Children of Child Marriages More Likely to be Malnourished

Child marriage has been outlawed for years in India. Women cannot legally marry before age 18. Yet the practice persists, particularly in poor, rural communities.

Dr. Anita Raj of Boston University has been studying the impact of child marriage.

In a paper published early last year, she found that girls who married before age 18 were more likely to have unwanted pregnancies.

In her newest research, Raj describes a link between child marriage and malnutrition among the babies born to these young women.

RAJ:  "Those mothers who marry younger were significantly more likely to have low-birthweight infants, to have infant and child mortality, and to have infant and child malnutrition."

But some of those differences were statistically attributed to factors like poverty and education. What was left were low weight and other signs of poor nutrition.

RAJ:  "Even if you control for the fact that women married as minors are more likely to have no formal education, are more likely to live in a rural context, are more likely to be living in abject poverty, you still see the malnutrition effect."

For her study, Raj and her colleagues used data from an Indian government survey. They analyzed information about 20,000 babies, most of them born to women who were under 18 when they got married.

Although her research doesn't explain what's causing the malnutrition among babies born to these very young mothers, Raj says it may be due in part to the fact that both the baby and mother are still growing, and are, in a sense, competing for scarce nutritional resources.

RAJ:  "Then, whatever she's taking in, there's going to be sort of a fight. And we think that sometimes that's going to cause health problems for the mother, and sometimes it's going to cause health problems for the baby. Either way, it's not a good health situation."

Anita Raj, an Indian-American herself, says she recognizes that child marriage is a longstanding cultural tradition in rural India. But she says it's associated with too many negatives, both for mother and child.

RAJ:  "It's sort of an inadequate justification for the continuation of the practice. Also, adolescent marriage does not necessarily mean adolescent pregnancy or childbirth. But it is happening because of the lack of support young girls have in terms of their knowledge and their access to [family planning] program in terms of their ability to negotiate what they want for their own bodies."

Raj's paper appears in the British Medical Journal.

Improve Your English Writing at our Website of the Week

Time again for our Website of the Week, when we showcase interesting and innovative online destinations.

This time it's an educational site where you can find more than 200 ways to improve your English.

BERGMANN:   "The Purdue Online Writing Lab is a sizeable collection of workshops, worksheets, [and] instructional materials in both English language and the various genres in which students and people working in the world are expected to write."

Linda Bergmann is director of the Purdue University Writing Lab, which includes a campus facility where students can hone their English skills, as well as the Online Writing Lab, known as the OWL, at owl.english.purdue.edu.

Bergmann says the goal is to provide users with a broad range of tools to boost their proficiency in written English.

BERGMANN:   "Everything from basic language skills of agreement of subject and verb, use of commas and other punctuation, complete and incomplete sentences, so that we can move from basic writing/language skills to the more sophisticated skills that graduate students, upper level undergraduates, and people in the work world use."

The Online Writing Lab was launched in the early days of the Web – in 1994 - and has built a global following from people who want to write better English.

BERGMANN:  "We get a lot of thank-you notes from people around the world, and also some schools in other countries use it as a writing handbook, as do some schools in the United States."

If you want to polish your English, take a look at the Purdue Online Writing Lab at owl.english.purdue.edu, or get the link from our site, VOAnews.com.

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You're listening to Our World, the weekly science and technology magazine from VOA News. I'm Art Chimes in Washington. 

This week, scientists reported the discovery of a new dinosaur species based on a fossil found in China.

The discovery, in Xinjiang Autonomous Region helps clarify the relationship between today's birds and dinosaurs that lived tens of millions of years ago.

Jonah Choiniere, a doctoral student at George Washington University here in Washington describes the new dinosaur in a paper published this week in the journal Science.

CHOINIERE:  "Haplocheirus was about two and a half meters long. We have most of the specimen from the skull all the way out almost to the tip of the tail. And somewhere around 15 kg. So it's pretty long and lightly built."

Haplocheirus is a member of a relatively new group of dinosaurs – new to science, that is. They were first described in the 1990s, and there is much about them that is still unknown. So this latest discovery helps fill out the puzzle.

CHOINIERE:  "And the paper we're publishing is on an animal that provides a lot of insight into the early evolution of this group. And the group's name is the alvarezsauroidia. What's most characteristic about them is, they have a really short arm that's incredibly powerful. And at the end of this arm there's pretty much a single large claw."

These were meat-eating dinosaurs who used that large claw, scientists believe, to dig out prey. Haplocheirus is the largest and also by far the oldest member of the group yet found – 63 million years older – close to the point in evolutionary history where birds and dinosaurs diverged. Alvarezsauroids have some bird-like features, and in fact had previously been classified as birds.

CHOINIERE:  "And so what this does is, takes alvarezsauroids and changes our hypothesis about where they go. We don't think they're birds now. We think they're closely related to birds but, in fact, a little further back in evolution. So they're a little further down the tree and closer to things like T-Rex."

Jonah Choiniere says he hopes to continue his research into the creatures of the Late Jurassic period, which he says should yield more insights into the early evolution of both birds and dinosaurs.

2010 Washington Auto Show Electrifies Public

The auto industry has suffered a lot in the global recession, and Toyota has been in the news this week for problems with accelerator pedals sticking in many of its vehicles. But at the Washington Auto Show, which opened this week, much of the focus is on new technologies to help vehicles go farther with less fuel and less pollution.

VOA's Rosanne Skirble was there

SKIRBLE:  Ford Motor Company president and CEO Alan Mulally officially opened the 2010 Washington Auto Show with this folksy pitch:

MULALY:  "I'm Alan. I'm from Ford, and I'm ready to take care of your car needs."

SKIRBLE:  The Ford CEO, whose company just reported its first profitable year since 2005, went on to detail a $400 million investment program to build its next generation Explorer at facilities in Chicago. The new mid-sized SUV – a best seller for Ford – would raise fuel efficiency 25 percent over the current model, a move Mulally says has been a top priority for the company.

MULALLY:  "Because of our size and our scale, when we make that kind of fuel efficiency, and we put [it] across the entire product line, we make a significant improvement in fuel mileage and CO2 reduction."

SKIRBLE:  Over at the General Motors exhibit, Jim Campbell, stands by a silver blue Chevy Volt, GM's soon-to-be released electric car. And Campbell described GM's plans to roll out other new electric vehicles:

   
CAMPBELL:  "We will have a Chevrolet Spark, which will be a new minicar entry, which will get excellent fuel economy. The Chevrolet Avail will be coming out. That's a vehicle that will have a 1.4 turbo engine, four cylinder, that will get about 40 miles per gallon on the highway. "   

SKIRBLE:  That's about 16 km per liter. The Chevy Volt is parked on a stretch of the Washington Auto Show called the Advanced Technology Superhighway. 

On the other end of the Superhighway we meet Ron Cogan, Editor and Publisher of the Green Car Journal. He's impressed with the variety he sees here.

COGAN:  "We're seeing electrification in a big way: plug-in hybrids, battery electric vehicles, hybrid-electric vehicles, hydrogen fuel cell vehicles that create electricity on board and drive an electric motor. We're seeing more advanced clean diesel vehicles, and advanced gasoline internal combustion. I think innovative answers in general – that's what we're seeing here in Washington."
 
SKIRBLE:  Cogan stands beside the Nissan Leaf, a zero emissions all-electric car that will hit the U.S. market in December. While the Leaf won the Green Car Journal's 2010 Green Car Vision of the Year Award, Cogan says many options are in play as the industry shapes its green future.

COGAN:  "As much as I am a believer in electric drive and battery electric cars, that's not the exclusive technology. To ignore clean diesel when we can make such an important change in how much fuel we use right now, that would be at our peril. To think that advanced internal combustion engines that get 20 percent, 30 percent better fuel efficiency aren't in the pipeline. That would be a wrong assumption." 

SKIRBLE:  The 240 million cars on U.S. roads create 20 percent of the nation's climate changing emissions, according to Ann Mesnikoff, who heads the Green Transportation Campaign for the Sierra Club, the nation's largest environmental group.

She is encouraged to see that automakers are thinking more seriously about cleaner, more efficient vehicles.

MESNIKOFF:  They have a whole range of technologies. But beyond having an electric car, we need to really see what the industry can do with their trucks. We need to see a lot of change in those gas guzzling vehicles."

SKIRBLE:  Mesnikoff adds that while new fuel economy standards will be required across the industry in 2016, pressure must be kept on automakers now, to further reduce polluting emissions.

Rosanne Skirble, VOA News, Washington.

And finally ... Apple Computer has introduced its long-awaited slate or tablet style computer, which it's calling the iPad.

The device is classy looking, with a 25 cm  screen, and measuring less than 15 millimeters thick.

It will run apps written for its smaller cousins, the iPhone and iPod Touch, and boasts a 10-hour battery life and a display with a virtual keyboard that knows whether its being held in landscape or portrait mode.

Of course, the new device has wireless connectivity, which CEO Steve Jobs demonstrated at preview event in San Francisco on Wednesday.

JOBS:  "And what this device does is extraordinary. You can browse the Web with it. It is the best browsing experience you've ever had. It's phenomenal to see a whole Web page right in front of you, and you can manipulate [it] with your fingers. It's unbelievably great, way better than a laptop, way better than a smart phone."

The usual Steve Jobs enthusiasm on display there along with the new product.

The iPad won't be in stores for a couple of months. But analysts are already pointing out some shortcomings: No built-in camera for video chats. No GPS. Maximum memory of just 64 gig. And no multitasking.  At least not yet. Apple's new iPad will sell for about $500 to over $800.

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