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逆向法巧学英语01.New Global Warming
Scientists have long believed that reducing carbon dioxide gas in the atmosphere is the best way to slow the warming of the Earth.
But new research suggests that reducing other gases may be a more effective way to slow climate change.
The study was presented by American space agency scientist James Hansen and a team of scientists at NASA's Goddard Institute for Space Studies.
They say that carbon dioxide levels have remained about the same during the past twenty-five years.
Yet they say the average temperature of the Earth's surface has increased.
The researchers found that the combination of other so-called greenhouse gases traps more heat in the atmosphere than once thought.
Such gases include methane,chlorofluorocarbons and ozone gases.
The new research suggests that limiting carbon dioxide and other gases is the best way to prevent the Earth from getting too warm.
Carbon dioxide in the atmosphere traps heat and keeps it near the Earth's surface.
It is produced by burning fuels that contain carbon such as coal,oil and wood.
Three years ago,one-hundred industrial nations signed an agreement designed to reduce carbon dioxide levels in the air by the year Two-Thousand-Twelve.
However,many countries objected to the climate change treaty.
They said efforts to meet the goals of the treaty would harm their industries.
The NASA scientists say more efforts should be made to limit the other gases.
They say other greenhouse gases appear to trap more heat in the atmosphere than carbon dioxide.
And technologies already exist to control most other greenhouse gases.
NASA scientists say reductions in methane,ozone and black carbon gases also would improve public health and agricultural productivity.
And they say the cuts would help the world'climate and improve the air.
Representatives of industries most affected by restrictions on carbon dioxide welcomed the findings.
But some scientists fear the study might be used to ease pressure on industrial nations that produce more carbon dioxide.
Others say it might be used to pressure developing countries to do more to control the release of harmful gases.
But most scientists agree that reductions are needed in all areas to prevent further global warming.


逆向法巧学英语02.New Evidence
A new study says that lakes and rivers in North America,Asia and Europe are freezing later and melting earlier than they did many years ago.
Some scientists say the findings provide more evidence that the Earth is getting warmer.
The findings were reported by John Magnuson and a research team from the University of Wisconsin,in Madison.
The researchers collected historical information from Eighteen-Forty-Six to Nineteen-Ninety-Five about twenty-six lakes and rivers.
The lakes and rivers are in the United States,Canada,Russia,Japan,Finland and Switzerland.
The researchers found that many lakes and rivers were freezing about nine days later and thawing about ten days sooner than they did one-hundred-fifty years ago.
They say those changes would mean a rise in air temperatures around the world of almost two degrees Celsius every one-hundred-fifty years.
Scientists say even small changes in the Earth's temperature can have serious effects on the environment.
Most scientists think the Earth is getting warmer and that people are causing the problem.
They say people are burning more fuels that trap heat in the atmosphere,such as coal and oil.
But some scientists say global warming is not real.
They say it is part of the natural system unaffected by human action.
The new results alone do not prove that the Earth's temperature is rising or that people are causing it.
But scientists say their findings support the idea that the Earth is getting warmer.
The researchers collected information from historical records.
They got the information from newspaper reports,fur traders' records,ship navigation records and notes of religious events.
They discovered the dates of ice formation and breakup on three continents since Eighteen-Forty-Six.
Some of the information was recorded because rivers and lakes were important for trade or transportation.
People also took note of freezing or thawing as a sign of the seasons.
The researchers note that the changes in ice formation on the lakes and rivers appear to have begun before Eighteen-Forty-Six.
But they say the changes were happening at a slower rate then.
They say most warming during the past one-hundred-fifty years is probably the result of human activity.


逆向法巧学英语03.Ozone Hole Grows
The hole in the protective ozone layer over Antarctica has grown bigger this year than at any time since scientists began measuring it fifteen years ago.
Ozone gas in the upper atmosphere blocks harmful ultraviolet radiation from the sun.
Ozone helps protect people from the sun's harmful ultraviolet rays.
Too much of this radiation can cause skin cancer or damage the eyes.
U-V radiation can also threaten agriculture and the environment.
Scientists say they are concerned that low ozone levels in the upper atmosphere could threaten heavily populated areas around the world.
In the Nineteen-Seventies,scientists expressed concern about man-made chemicals called chlorofluorocarbons.
They said these C-F-Cs were destroying the protective ozone layer.
C-F-Cs destroy ozone in the presence of sunlight.
They were once widely used in aerosol sprays and in cooling equipment.
But most countries agreed to stop producing C-F-Cs after a worldwide ban in the late Nineteen-Eighties.
Over the years,scientists have observed a huge loss in ozone over Antarctica.
Antarctica is the ice-covered continent that covers and surrounds the South Pole.
The loss of ozone takes place during its extremely cold winter season from June until September.
Scientists believe that sunlight causes chemical reactions in the cold air over Antarcitica that can destroy ozone.
This creates a huge ozone hole.
The hole gets smaller as temperatures begin to rise in November.
The temperature over Antarctica affects the size of the hole each year.
The National Oceanic and Atmospheric Administration said that the ozone hole increased to more than twenty-seven-million square kilometers for a few days last month.
Scientists say this is the largest size ever recorded.
It is an area about the size of North Amercia.
Record low temperatures in the upper atmosphere are believed to the cause.
For several years,the hole has extended over populated areas at the southern end of South America.
This year,cities in Chile and Argentina were hit with dangerous levels of ultraviolet radiation.
And experts say it is possible that the situation could affect areas in South Africa,Australia or New Zealand.


逆向法巧学英语04.Giant Jellyfish
Large numbers of huge Australian jellyfish have been found in the waters of the Gulf of Mexico near the southern United States.
Scientists want to know more about them and what long-term effects their presence may have.
A jellyfish is an unusual sea creature.It is not a fish.
It does not have a backbone.It has a soft body shaped like a bell.
And it has long string-like structures called tentacles.
There are more than two-hundred different kinds of jellyfish in all of the world's oceans.The come in all shapes and sizes.
Jellyfish are often a problem for people swimming at the beach because some of them can sting.
Some jellyfish stings can be very painful.But most jellyfish are harmless to humans.
Tens of thousands of spotted Australian jellyfish have washed up on beaches off the southern coasts of Alabama,Florida,Louisiana and Mississippi.
Observers say they can easily be seen from the air.
Scientists say the jellyfish have grown two times their normal size.
They are more than one-half meter across and weigh,at least eleven kilograms.
The huge creatures are causing problems for people living near coastal waters of the Gulf of Mexico.
Swimmers are avoiding the beaches.And the jellyfish are getting caught in fishing nets and in boat engines.
Scientists say the jellyfish may have a serious effect on the environmental system in the Gulf of Mexico.
Scientists fear the jellyfish are eating the eggs and young creatures of the area's fish,shrimp and crabs.
They say this may harm the valuable fishing industry in the area.
Spotted jellyfish are native to Australia.
They have been moving to the Caribbean Sea for twenty years.
But this is the first time they have been seen so far north.
They invaded the Gulf of Mexico in early June.
Experts believe the jellyfish were caught in unusual waves that moved them north to the Gulf of Mexico.
Scientists in Mississippi and Alabama are doing research to find out more about the invaders and how much they eat.
They hope that increased rainfall or cold weather will kill or control the jellyfish.
Scientists do not know if the jellyfish will survive the winter.
If they do,their effect on the environment of the Gulf of Mexico could be an even bigger problem next year.


逆向法巧学英语05.2000 Summer
BOB DOUGHTY:And this is Bob Doughty with the VOA Special English program,EXPLORATIONS.
The Summer Olympic Games begin this week in the city of Sydney,Australia.
Today we tell about the Olympics and some of the American Olympic athletes.
STEVE EMBER:The world's most famous sports event is the Olympic Games.
Five-million people are expected to attend the Summer Olympic Games this year in Sydeny,Australia.
They include leaders and officials from many countries.
About fifteen-thousand reporters are there.
More than three-thousand-million people are expected to watch the games on television.
More than ten-thousand athletes from two-hundred countries will compete in twenty-eight different sports in the Summer Games.
They will be trying to win medals-gold for first,silver for second and bronze for third-in about three-hundred events.
New additions to the Summer Olympics this year include synchronized diving,women's weight lifting,trampoline,women's pole vault and the triathlon.
BOB DOUGHTY:The name of the modern Olympic Games comes from games held in ancient times.
The games are said to have started in the ancient Greek city of Olympia,about two-thousand-seven-hundred years ago.
The first thirteen Olympic Games were foot races during festivals held to honor the Greek god,Zeus.
Winners were honored with a crown of olive leaves placed around their heads.
Greece continued to hold the Games every four years for the next one-thousand years.
Then the Games stopped.The ancient Romans banned the Olympic Games when they ruled Greece.
They destroyed Olympic temples and sports fields.
STEVE EMBER:The first modern Olympic Games were held in Athens,Greece in Eighteen-Ninety-Six.
French diplomat Baron Pierre de Coubertin proposed a world celebration of sports like the ancient games of Greece.
He believed the international event would provide a way for athletes of all nations to become friends.
The official symbol of the Olympics shows five rings.
Baron de Coubertin designed the symbol in Nineteen-Thirteen.
The five rings represent the linking through sports of five parts of the world:Europe,Asia,Africa,Australia and the Americas.
The colors of the rings are blue,yellow,black,green and red.
The flag of every nation competing in the games has at least one of these colors.
Under the rings is the Olympics saying in Latin:"citius,altius,fortius."The words mean in English--swifter,higher,stronger.
BOB DOUGHTY:The Olympic flame links the old and new games.
In ancient Olympia,a fire burned in honor of the god Zeus during the sports competition.
Now,runners carry a flame from Olympia to every new Olympics.
This year's fire was lit in Olympia,Greece on May tenth.
Each person ran with it for one kilometer and then passed it to another runner.
Before the flame reached Sydney,it was carried by more than thirteen-thousand people.
The flame was flown from Athens,Greece,to the island of Guam in the South Pacific.
It then was carried by individuals who traveled by foot,boat or vehicle through the Pacific islands to Australia.
This Olympic flame has traveled farther than any other.
This Friday,September fifteenth,a runner will use the flame to open the twenty-seventh Summer Olympic Games.
The Olympic flame will burn during the Games.It will be put out during closing ceremonies.
STEVE EMBER:Some of the athletes taking part in the Summer Olympics have trained for these events since they were children.
One is American swimming champion Lenny Krayzelburg.
Lenny Krayzelburg was born in the former Soviet Republic,Ukraine.
He started swimming when he was five years old.
A coach told Lenny's father that he could be a great athlete.
The coach said Lenny was burn to swim the backstroke.
The Krayzelburg family left Ukraine and arrived in the United States when Lenny was thirteen.
They settled in Los Angeles,California.Lenny continued to swim in competitions.
In Nineteen-Ninety-Four,Lenny Krayzelburg's swimming skill won him financial support to attend the University of Southern California.
In Nineteen-Ninety-Eight,he became the first swimmer in twelve years to win all the backstroke races at the World Swimming Championships.
Last August,he broke the American record in the two-hundred meter backstroke for the fifth time.
Later in the month,he broke the world records for the two-hundred meter and one-hundred meter backstroke.
Swimming experts say Lenny Krayzelburg should win both the one-hundred and two-hundred meter backstroke races at the Summer Olympics this year.
Lenny Krayzelburg says he will be unhappy if he does not win three gold medals in Sydney.
BOB DOUGHTY:Three members of the same American family will compete in Sydney.
Hazel Clark,Jearl Miller-Clark and Joetta Clark-Diggs are all members of the track and field team.Hazel and Joetta are sisters.
Jearl is married to their brother,J.J.Clark.He is the coach for all three women.
It is unusual for members of the same family to compete in the Olympics.
But it has been done.Jackie Joyner-Kersee and her brother's wife Florence Griffith Joyner both competed in past Olympics.
But they did not compete in the same event.The Clarks do.
They all compete in the eight-hundred meter women's foot race.
Hazel Clark is the youngest in the Clark family of runners.
She was the fastest in the Olympic trials.
Her brother's wife,Jearl Miles-Clark,was second.
Jearl has already won medals in two earlier Olympic Games.
Joetta Clark-Diggs finished third.She is the oldest,at thirty-seven.
That was the first time three family members finished first,second and third in the same United States Olympic trials race.
And this will be the first time three Americans competing in one Olympic race are from one family.
Many people will be watching the eight-hundred meter race to see if the three members of the Clark family can win all three medals.
STEVE EMBER:Another international sports event will take place in Sydney following the Summer Olympics.
The Paralympic Games will be held from October eighteenth to the twenty-ninth.
All the athletes who compete in the Paralympics have a physical disability.
About four-thousand disabled athletes will compete this year.
One American athlete who will compete in the Summer Olympics is already a Paralympics champion.
Her name is Maral Runyan.She won the one-hundred,two-hundred and four-hundred meter races and the long jump at the Nineteen-Ninety-Two Paralympics.
She also won the Pentathlon competition in Nineteen-Ninety-Six.
This year,she will become the first legally blind athlete in the Summer Olympic Games.
Marla Runyan suffers from an incurable eye problem called Stargardt's Disease.
It destroys part of the retina of the eye,and blocks the center of vision.
Marla Runyan has been legally blind since she was nine years old.
She has been taking part in track events since she was in high school.
Marla Runyan will compete in the women's fifteen-hundred meter foot race at the Sydney Games.
She says her goal was not to be the first legally blind Onlympian.
She just wanted to take part in the Olympics.
But her story has helped other disabled people find the strength to try to reach their goals.
And Marla Runyan says that makes her feel very good.
BOB DOUGHTY:The Two-Thousand Summer Olympic Games will end October first,after sixteen days of competition.
The next Summer Games will be held four years from now,in Athens,Greece.
The Summer Olympic and the Winter Olympic Games used to be held in the same year,every four years.Now,however,they are separated.
The next Winter Games are less than two years away.
The western American city of Salt Lake City,Utah is busy preparing for the Winter Olympics of Two-Thousand-Two.


逆向法巧学英语06.Olympics Drug Use
STEVE EMBER:This is Steve Ember with the VOA special English program in the NEWS.
Over the next two weeks,ten-thousand athletes from two-hundred countries will compete in the Summer Games in Sydney,Australia.
They will try to live by the Olympic saying,"faster,higher,stronger."
But in the world of sports,experts say too many athletes use performance-improving drugs to reach these goals.
The International Olympic Committee says drug use risks the health of athletes and violates the rules of sport.
If an athlete fails a drug test before an event,he or she is banned from the competition.
Athletes who fail a test after winning an event lose their medals.
This year,the I-O-C says it is testing more Olympic athletes more often than ever.
Some experts say this is still not enough.They say it is still too easy for athletes to use drugs and pass the tests.
The International Olympic Committee bans six kinds of substances and three methods of increasing performance.
One group of banned drugs is anabolic steroids.These substances increase muscle strength.
Experts say that some fast-acting steroids now leave the body in just a few hours.
That makes them extremely difficult to find.
Another banned drug is known as EPO,Erythropoietin increases the production of red blood cells.
The resulting increase in oxygen can improve an athlete's performance in both short and long distance events.
Officials at the Sydney Olympics are testing for EPO for the first time this year.
But experts say the officials may not find any,if an athlete stopped taking the drug about a week before the Games began.
Another banned substance is human growth hormone,which builds muscle size and strength.
Others include beta blockers and diuretics.Beta blockers are taken to calm nerves.
Diuretics increase the production of red blood cells.They also increase urine production,which can hide the presence of banned drugs.
Still another illegal way to increase production is called blood doping.
Blood is taken from an athlete.Red cells are removed and cooled.
One month later,the blood is put back into the athlete's body.This increases the amount of oxygen the body carries.
The newest way that some athletes try to improve their performance is with blood substitutes.
These also increase the amount of oxygen in th blood.
Many of these banned substances are dangerous.
They can thicken the blood,cause an enlarged heart,or damage the reproductive system.They can even kill.
Yet a recent United States government study said about thirty percent of Olympic athletes use illegal drugs.
Winning a medal can mean fame and a chance to earn a great deal of money.
Some athletes say taking drugs for a few years will not hurt them.They believe the risk to their health is a small price to pay.


逆向法巧学英语07.Green Olympic Game
The Olympics in Sydney,Australia,is being called the first environmentally-friendly Games in history.
Olympic organizers and environmental groups are trying to protect the environment during the summer games.
Organizers say they hope these environmental efforts will be an example for other large sporting events.
Seven years ago,Sydney competed with other cities to hold the Olympics.
Sydney won the Games with the support of environmental organizations like Greenpeace.
City officials promised to meet the Organization's environmental goals.
Olympic organizers have reached many of their goals.
They are saving energy by increasing the use of solar power.
They built structures with materials that can be treated and used again.
Half of all water used during the Games comes from rainwater.
And people are using buses and modern trains instead of cars to get to the Games.
Even the historic Olympic torch has become cleaner.
Almost three-thousand people are involved in removing waste products twenty-four hours a day from the area of the Games.
A large amount of the waste material is being reused.
Paper containers for holding food are made of a cornstarch material that breaks down in the environment.
This waste will be taken to a giant worm farm to be eaten by worms.
Environmental activists are praising the use of energy from the sun for houses in the Olympic Village.
Athletes are staying in them during the Games.
Some people have criticized the city.
They say the government failed to meet its promise to clean up an Olympic center at an area called Homebush Bay.
The waterway was once used by manufacturing companies to dump chemical pollution.
Greenpeace says it still contains five-hundred-thousand tons of dioxin chemicals.
Environmentalists are also concerned about the use of gases in the cooling systems at the Olympic centers.
They say these so-called greenhouse gases damage ozone in the atmosphere which can increase temperatures on Earth.
Organizers say most of Olympic environmental failures resulted from the lack of technology.
But they say they have made progress.They hope to repeat their environmental efforts at future Olympic Games.


逆向法巧学英语08.Growing Nerve Cell
SARAHLONG:This is Sarah Long.
BOB DOUGHTY:And this is Bob Doughty with Science in the News,a VOA Special English program about recent developments in science.
Today,we tell about scientists who grew nerve cells from special stem cells.
We tell about cancer patients who suffer memory loss from chemotherapy treatments.
And we tell about a rare red panda born in an American zoo.
SARAH LONG:American scientists have found a way to change bone marrow cells into nerve cells like those found in the brain and the spinal cord.
The discovery may lead to safe and successful treatments for nerve injuries and brain disorders.
The work is being done by Ira Black and a team of researchers at the Robert Wood Johnson Medical School in Piscataway,New Jersey.
Doctor Black said he began the research to study how the body's cells,with the same genetic material,become many different kinds of cells.
Some become blood cells.Others become liver cells or brain cells.
Doctor Black wondered how this happened.What caused the cell to change into one kind or another?
He hoped to learn if scientists could make the same kind of changes in cells.
BOB DOUGHTY:Special cells called stem cells are produed in bone marrow,the material inside the large bones of the body.
The stem cells move from the bone marrow to the place where they are needed.
For example,if the body needs liver cells,stem cells travel to the liver.
They become liver cells and do all the work that other liver cells do.
Doctor Black and his team removed stem cells from the bone marrow of rats.
They put the rat stem cells into laboratory dishes and grew many more of them.
Then they added a chemical called beta mercaptoethanol.
Doctor Black had discovered earlier that beta mercaptoethanol had a special effect on cells.
It seemed to block other chemicals that prevented cells from becoming nerve cells.
SARAH LONG:Doctor Black said laboratory stem cells treated with beta mercaptoethanol changed within minutes.
He said they looked exactly like nerve cells
They began growing long,hair-like parts,just as nerve cells do.
The researchers found it was possible to change about eighty percent of the stem cells into nerve cells.
Tests showed that the newly-created nerve cells did all the chemical work that nerve cells usually do.
Doctor Black transplanted the rat nerve cells he had produced in the laboratory into the brains and spinal cords of living rats.
The laboratory nerve cells survived for months in the bodies of the rats.
BOB DOUGHTY:Other scientists praised the discovery.
One was William Greenough,of the Beckman Institute for Advanced Science and Technology at the University of Illinois.
Doctor Greenough said the discovery was an important step toward developing new technologies for the repair of a damaged brain.
He noted that many scientists are working with embryos or animal tissue to try to develop cells to replace damaged human cells.
But the body's defense system often rejects such foreign cells.
That would not be a problem with replacement cells grown from a person's own stem cells.
Scientists say,however,that a huge amount of work must be done before laboratory-produced nerve cells can be used to treat human injury or disease.
The work done by Doctor Black's team is described in the Journal of Neuroscience Research.


逆向法巧学英语09.Chemotherapy
SARAH LONG:You are listening to the Special English program SCIENCE IN THE NEWS on VOA.
This is Sarah Long with Bob Doughty in Washington.
Chemotherapy is a common way to fight cancer.
Doctors give patients powerful drugs to kill cancer cells.
However,chemotherapy drugs often are poisonous to healthy cells as well.
Patients often suffer unwanted side effects.
Among the most common side effects are a sick feeling in the stomach and the uncontrolled expulsion of food from the mouth.
Other side effects are hair loss,a feeling of weakness and infection.
In addition,patients who have traditional chemotherapy often say they suffer from temporary memory loss and reduced thinking ability.
Tim Ahles of Dartmouth Medical School in Hanover,New Hampshire,organized a study of the problem
BOB DOUGHTY:Doctor Ahles compared cancer patients who had traditional chemotherapy to patients who had limited treatments.
The two groups were tested for memory,reading ability,and the ability to think clearly.
Doctor Ahles says his study showed that patients who had traditional chemotherapy were two times as likely as the other patients to do poorly in the intelligence tests.
Doctor Ahles presented the findings to a group of cancer patients who had chemotherapy.
He says those patients felt better knowing that the study found evidence of what many of them already knew.
Doctor Ahles says almost everyone who has chemotherapy experiences problems with memory and thinking.
He says the problems are most common from the middle of treatment until up to four months after the chemotherapy stops.
He says the ability to think clearly begins to improve later.
SARAH LONG:Recently,research scientists in Canada reported similar findings about chemotherapy.
The findings were reported in the Journal of Clinical Oncology.
Researchers from Princess Margaret Hospital in Toronto studied breast cancer patients who were given chemotherapy.
They compared the patients to other women who were not receiving the treatment.
The Canadian researchers found the women taking the anticancer drugs did worse in tests of memory and language than the other women.
The researchers say doctors and patients should understand the problem when making treatment decisions.
However,they say this possible problem should not be used as an argument against chemotherapy treatment.


逆向法巧学英语10.Red Panda
BOB DOUGHTY:A rare Chinese red panda has been born at the Red River Zoo in Fargo,North Dakota.
Officials there say the birth is believed to be the first at a North Dakota zoo.
The Red River Zoo opened last year.
The cub's mother is a female red panda called Tsaka,which means mountain in Tibetan.Its father is named Chang.
Keepers at the zoo were surprised to discover that Tsaka had given birth in June.
They did not announce the birth until they were sure the panda cub would survive.
Zoo officials believe the cub is probably male.They have named it Liwu which means gift in Mandarin Chinese.
About fifty Chinese red pandas live in zoos in the western part of the world.
In the United States,the Knoxville Zoo in the state of Tennessee is best known for its programs to help red pandas reproduce.
More pandas have been born there than at any other zoo in the country.
SARAH LONG:The red panda is a small member of the animal family that includes the larger and more famous giant panda.
The red panda is similar in size and appearance to a raccoon.
Red pandas are known for their soft fur and long thick tails.
Panda cubs are very small when they are born.
They weigh about two-hundred grams when they are one week old.
When cubs are three months old,they start to look like adult pandas.Adults weigh about four kilograms.
BOB DOUGHTY:The red panda lives in the Himalayan Mountains in Nepal,Bhutan,Burma and southern China.
It is difficult to know for sure how many red pandas live in the wild.
That is because the bamboo forests where they live are very thick.
However,there is increasing evidence that the red panda is becoming endangered.
The major threats to pandas are said to be the loss of their native forests and illegal hunting.
For example,widespread cutting of forests for wood and farmland in China has destroyed large areas of the pandas'environment.


逆向法巧学英语11.Blood Vessels
BOB DOUGHTY:And this is Bob Doughty with Science in the News,a VOA Special English progrm about recent developments in science.
Today,we tell of a discovery about blood vessels and cancer.
We tell about a robot that eats food.And we tell why it is never too late to stop smoking.
SARAH LONG:Scientists at the Johns Hopkings University cancer center in Baltimore,Maryland have discovered what may be a new weapon against cancer.
They found forty-six genes that are active in the cells of blood vessels that supply blood to cancers.
The genes are not active in any other blood vessel cells.
Scientists led by Kenneth Kinzler and Bert Vogelstein made the discovery.
They found that seven of the genes seem to help in the creation of new blood vessels to cancers.
So,these genes may be necessary for a cancer to get more blood.
Without more blood,the cancer cannot grow.
BOB DOUGHTY:Scientists say they may be able to use these genes to develop new cancer treatments.
One such treatment might use drugs to prevent these genes from working.
That could prevent a cancer from forming new vessels to get the blood it needs.
Another treatment might use poisons to destroy a protein produced by genes to make blood vessels.
Scientists could attach the poison to a special antibody.
It would search through the body to find only that protein that builds blood vessels to cancers.
It would put the poison in the protein to destroy it.
Only that protein would be destroyed.Healthy tissue would not be harmed.
But the cancer would not get the blood it needs to grow.


逆向法巧学英语12.A Human-like
SARAH LONG:Scientists have tried for a long time to invent a human-like machine.
Devices that can operate themselves and do some things humans can do are called robots.
Now,Stuart Wilkinson has invented a robot that can eat food.
This food is used to produce energy that the robot needs to work.
It is the first robot to be completely powered by food.It is called a gastrobot.
Mister Wilkinson works at the American University of South Florida in Tampa.
He has named his gastrobot Chew Chew.The robot has twelve legs and looks like a train.
It has three parts.Each part is a meter long.Chew Chew's stomach is a device that uses bacteria to break down food.
The bacteria,E,Coli,produce substances called enzymes,which can break down carbohydrates.
The process releases electrons that are used to power a battery.
In this way,chemical energy is used to produce electricity.Humans get energy from food in a similar way.
BOB DOUGHTY:The inventor says the gastrobot is only being fed sugar right now.
This is because the bacteria break down almost all the sugar and produce very little waste.
The only waste produced is carbon dioxide gas and water.Chew Chew can also eat vegetables.
Scientists say the first versions of such a robot could be used to cut grass,for example.
The robot could power itself with the grass it is cutting.
Mister Wilkinson hopes to improve the design of the robot so that it can feed itself.
In the future,scientists hope to invent robots that can produce enough energy to power a car or a train.
Another idea is an underwater robot that could eat fish.
Mister Wilkinson says a gastrobot eating meat would produce the most energy.
However,he says it might be dangerous to give robots their first taste of meat.
They might realize that humans are meat and can be eaten too.


逆向法巧学英语13.Spices
SARAH LONG:And this is Sarah Long with the VOA Special English program SCIENCE IN THE NEWS.
Today,we tell about spices and some interesting ideas about these substances.
BOB DOUGHTY:People have used spices in food for thousands of years.
Some spices are valued for their sharp taste.Others are chosen for their smell.
Spices are made from plants or vegetables.Common spices include pepper,cloves,ginger,mustard,cinnamon and dill.
Spices come from different parts of plants.
For example,cinnamon comes from the hard outer covering of cinnamon plants.
The spice ginger comes from the part of the ginger plant that grows underground.
Spice plants grow in many countries.
The Molucca islands in Indonesia,for example,are famous for producing spices such as cloves,nutmeg or mace.
Vanilla comes from plants growing in south America.
Many people grow spice plants outside their homes.
Then they dry the plants for later use.
Some common spice plants can even be grown inside a house if they are placed in sunny areas near windows.
SARAH LONG:Spices have influenced world history.
For example,the Goth people of Europe defeated Roman forces in a battle almost two-thousand years ago.
After the fighting ended,the leader of the Goths is said to have demanded five-thousand pounds of gold and three thousand pounds of pepper.
Later,explorers like Marco Polo,Vasco de Gama and Christopher Columbus discovered new lands while seeking to expand trade with spice-growing areas in Asia.
The Italian cities of Genoa and Venice became powerful because they were at the center of this spice trade.
The spice trade was so important to national economies that rulers started wars in their struggle to control spices.
BOB DOUGHTY:Spices are commonly used because they can make food taste better.
Two researchers at Cornell University in the American state of New York say there is another reason for spice use in cooking.
They say spices contain substances that kill or slow the growth of dangerous bacteria in food.
It is a known fact that some spices destroy bacteria.
Spices long have been used to keep food safe to eat.
In the past,spices also were used to help protect the condition of dead bodies.
The study reportedly was the first to investigate the idea that spices are used in cooking because they destroy dangerous bacteria.
SARAH LONG:Researchers Paul Sherman and Jennifer Billing examined more than four-thousand-five-hundred directions for cooking meat or fish.
They found these recipes in traditional cookbooks published in thirty-six countries around the world.
The two researchers studied the spices used in the recipes and tested them against thirty kinds of bacteria.
The researchers say people use spices because they make food taste good,and bacause spices protect people against disease.
They say people who used spices many years ago lived healthier and longer lives because the spices killed disease-causing bacteria in their food.
They say the use of the spices spread in some areas because the people who used spices shared these safer cooking methods with their children and friends.
BOB DOUGHTY:Professor Sherman and Mizz Billing found that onion and garlic are used most often in areas where weather conditions are very warm.
These two spices stopped almost one-hundred percent of the bacteria against which they were tested.
Hot peppers stopped the growth of eighty percent of the bacteria tested.
The researchers found that foods from warm climates contain more onion,garlic and hot peppers than foods from other areas.
For example,eighty percent of the recipes from Indonesia called for garlic and onion.
Seventy-seven percent called for the use of hot peppers.
But the use of spices was not as common in cooler climates.
Onions appeared in fifty-six percent of the recipes from Ireland.
Garlic was called for in twenty-three percent of the Irish recipes,and hot peppers in only two percent.
In Norway,no recipes called for garlic and only twenty percent called for onions.
SARAH LONG:The Cornell University researchers found that countries with warm climates generally use many different spices in many of their foods.
Countries with cooler climates use fewer spices in fewer foods.
The researchers also found that spice use within large countries sometimes differed from one area to the next.
Examples include the northern and southern United States,and northeastern and southwestern China.
The study showed that the recipes from warmer areas used more spices than the recipies from cooler areas.
These findings support the idea that the most effective spices are used mostly in areas where bacteria destroys foods quickly.
Such areas generally are very warm.
BOB DOUGHTY:Professor Sherman and Mizz Billing rejected other attempts to explain the large amount of spices in foods from,warmer climates.
One possible explanation is that people in warm climates use more spices because spices cause their bodies to release sweat.
It says the liquid from sweat may help to cool the skin.
The researchers say that only one spice they studied,hot peppers,can cause sweating.
Ant it is not one of the most popularly used spices.
The researchers also note that hot pepper do not produce sweating in all people who eat them.
SARAH LONG:Another explanation for the use of spices is that they hide the bad smell and taste of food already being destroyed by bacteria.
The researchers rejected this idea.
They say people who eat food with harmful bacteria would be more likely to get sick and die,so this method of cooking would not be passed on to others.
A third explanetion for the increased use of spices in warmer climates is that people use spice plants growing near them.
The study found that people do not use every spice grown in their local area.
And,they do use many spices imported from other countries.
For example,pepper is used in all thirty-six countries in the study,but it grows in only nine of them.
BOB DOUGHTY:The American researchers say the smells and taste of spice plants probably have changed over time to protect the plants against bacteria,insects,and fungi.
They say this is important because humans are affected by many of these same enemies.
The bacteria and fungi that live on and inside dead plants can be harmful to humans.
If spices kill such substances or stop their poisons,spice use might reduce the likelihood of developing food poisoning or other sicknesses.
SARAH LONG:Not everyone agrees with some of the study findings.
Critics argue that economic and cultural forces can explain spice use in many countries.
Frederick Simoons is a retired American expert of world cultures.
He says people very often explain things from the past in terms of modern knowledge.
Mister Simoons notes that garlic was often banned for religious leaders because garlic has a strong smel
He said such smells were not permitted in ancient times for people wishing to communicate with spiritual being
BOB DOUGHTY:One interesting finding discussed by the Cornell researchers is the rate of food poisoning in Japan and Korea.
Food poisoning affected about thirty of every one-hundred-thousand Japanses from Nineteen-Seventy-One until Nineteen-Ninety.
But only three of every one-hundred-thousand Koreans had the problem during the same period.
The researchers were surprised by this because both countries have similar climates.
They noted,however,that Korean food is spicier than Japanese.
They say Korean food also calls for more spices known to have anti-bacterial effects.
The researchers do not know why Japanese recipes do not call for the more effective spices.
But they say the spices used in Japanese cooking may have been enough to protect people from sickness in the past,but not now.


逆向法巧学英语14.Kennedy Space
SHIRLEY GRIFFITH:This is Shirley Griffith.
STEVE EMBER:And this is Steve Ember with the VOA Special English program,EXPLORATIONS.
Today we tell about what visitors can see and do at the Kennedy Space Center in Cape Canaveral,Florida.
It is the place where the American space agency NASA launches its space shuttles.
SHIRLEY GRIFFITH:It is morning on September eighth,Two-Thousand.
You are visiting the Kennedy Space Center.The voice you just heard is that of a NASA announcer.
He is counting the seconds to the launch of the space shuttle Atlantis.
The shuttle-orbiter vehicle is making its twenty-second trip into space.
Five American astronauts and two Russian cosmonauts are waiting inside the shuttle.
They are about to travel three-hundred-fifty-four kilometers to the International Space Station.
Their job is to prepare the station for the first people who will live there.
Within days the Atlantis crew will have transported two-thousand kilograms of food,water,exercise equipment and other supplies into the station.
STEVE EMBER:Thousands of mechanical devices must be perfect before launch director Mike Leinbach can give the command"Go!"Tests show the equipment is working well.
Yet the weather remains a worry.Air Force and NASA experts are watching carefully.
Rain over the nearby Atlantic Ocean may be moving into the launch area.
A storm could delay the flight for weeks.
A NASA pilot is flying an airplane around the launch area to observe the weather.
This pilot reports that the shuttle can safely leave Earth.The weather experts agree.
A NASA announcer talks to the waiting crowd.
He explains that scientists and engineers on the ground are testing all the spacecraft's systems.
One after another,you can  hear them report that their systems are"Go!"The final count before the launch begins.
SHIRLEY GRIFFITH:You feel the ground shake.You see yellow flames and smoke shoot out from under the rocket.
Atlantis climbs,followed by white smoke.The spaceship separates from the equipment that lifted it.
Atlantis is now on its way to chase the International Space Station.
STEVE EMBER:You have seen a space shuttle launch.
Now you want to learn about some of the work that made it possible.
So you go to the Kennedy Space Center Visitor Complex.This large educational center is not far from the launch area.
The name honors John F.Kennedy,thirty-fifth president of the United States.
The permanent visitor area opened in Nineteen-Sixty-Seven.
That is when NASA was preparing to launch the first astronauts to the moon.
Since then,millions of people have walked around the seven structures of the Visitor Complex.
SHIRLEY GRIFFITY:You take a bus to see some of the center's most important places.
One of these is called the VAB-the Vehicle Assembly Building.
It is the third largest building in the world.
It is one-hundred-sixty meters tall.The building covers more than three and one-quarter hectares.
Rocket-lifting devices,fuel tanks and shuttles are joined here.
When the spacecraft is ready,a long vehicle called a crawler carries it to one of the center's two launching areas.
Both are only a short distance away.However,the trip takes several hours.
The loaded crawler can travel only one and one half kilometers per hour.
STEVE EMBER:Now you decide to get a close look at a rocket.
So you go to an area called the Rocket Garden.A number of rockets stand in this area,noses pointed to the sky.
One of these rockets lifted the first American satellites into space in the Nineteen-Fifties.
Another lifted the first American astronaut into space.
Alan Shepard made that flight in Nineteen-Sixty-One.
Still another rocket launched the first American to orbit the Earth-John Glenn.
That happened in Nineteen-Sixty-Two.
One rocket in this area is not standing.The huge Apollo Saturn One-B lies on its side.
It is the only rocket in the Garden that NASA designed.
The other rockets were built as military missiles.
NASA later redesigned them for peaceful exploration of outer space.
SHIRLEY GRIFFITH:Next,you want to see the inside of a spacecraft.So you enter the Explorer.
This vehicle is a copy of a full-size space shuttle orbiter.
Once inside,you may be surprised at how the astronauts are able to work in such a small amount of space.
The pilot of an astronaut crew flies the shuttle from a crowded place called the flight deck.
Shuttle crews work on experiments in an area called the middeck.
They also sleep,eat and use the bathroom on the mideck.
Astronauts who work outside the spaceship repair satellites in an area behind the middeck.
This is the cargo bay.The Russian space station Mir connected with shuttles in this cargo bay area.
Inside the cargo bay is a fifteen-meter-long mechanical arm.
It help the astronauts work in space.Here you will also see a curved device covered with shining gold material.
In Nineteen-Ninety-Two it rescued a satellite that was traveling in the wrong orbit.
STEVE EMBER:By now you probably have questions about the space program.
You can  get answers by attending a meeting with an astronaut.
On this day the speaker is aerospace engineer John Fabian.He has served on two space flights.
A child from Japan asks Mister Fabian if he always wanted to be an astronaut.
He says he did but he was too tall.He had to wait until spacecraft were designed with enough space for his height.
The earliest American astronauts were required to be average height or less.
Mister Fabian has special advice for the many children in the Visitor Complex this day.
He advises them to study hard so they can be a part of an exciting future.
SHIRLEY GRIFFITH:Children can learn about the space program from many exhibits in the Visitor Complex.
For example,a colorful,often funny presentation called"Robot Scouts"tells about the activities of robots.
These machines are designed to do special tasks in the space program.
Another exhibit offers a document for travel among the planets.
It asks young visitors to identify planets and space equipment like the Hubble Space Telescope.
Visitors can study the exhibits and supply the answers.
Other devices in this area of the Visitor Complex give information about the planets that orbit our sun.
These interactive machines provide facts in unusual way that helps visitors remember them.
STEVE EMBER:You can also watch several educational movies about space.
A movie called"Quest for Life"explores the possibility of finding forms of life on what may be two-thousand-million other planets in the universe.
NASA scientists say many of these planets may have the elements required to support life.
Another movie tells about a future community in space.
"L-Five,First City in Space"is the story of a human city built far from Earth.
It tells some of the many dangers that the first space citizens may face.
NASA scientists helped produce the film,which shows events that seem very real.
For example,water from a waterfall in the movie appears to be about to flow directly on your head.
You wear special eyeglasses to see the action.
SHIRLEY GRIFFITY:The sun is going down now.Soon the Visitor Complex will close for the day.
But before you leave,you visit the Space Mirror.The Mirror is a large black stone wall.
It contains names of astronauts killed while training or serving in space.
Those honored here include three astronauts who served in the early days of the American Space Age.
Gus Grissom,Roger Chaffee and Edward White died in a Nineteen-Sixty-Seven fire on the ground.
The names of the crew who died in the space shuttle Challenger also are on the wall.
Challenger exploded shortly after its launch in Nineteen-Eighty-Six.
Six astronauts and school teacher Christa McAuliffe died in the explosion.


逆向法巧学英语15.Malignant Melanom
Last month,United States Senator John McCain was treated for the most serious kind of skin cancer,malignant melanoma.
Doctors removed the cancer in an operation.
Later tests showed that the cancer had not spread from the skin to other organs.
Malignant melanoma can be cured if it is removed before it spreads to other parts of the body.
But the disease can kill if it spreads.
The World Health Organization says two-hundred-thousand people around the world are found to have malignant melanoma each year.
About forty-seven-thousand new cases of melanoma are found in the United States each year.
The American Dermatology Association says almost eight-thousand Americans will die this year from the disease.
The cancer begins in body cells that produce a brown color.
It usually first grows in a dark area of skin called a mole.
Melanoma most often is recognized as a dark area with an unusual shape.
An operation to remove the cancerous cells can cure melanoma if the cancer has not spread.
Doctors treat melanoma that has spread with chemotherapy drugs to kill any cancer cells that were not removed in the operation.
Radiation also may be used to kill cancerous cells and reduce the size of any cancerous growths.
The newest kind of treatment for melanoma is the use of molecules produced by the human body.
The purpose of this treatment is to improve the body's own defenses against cancer cells.
The five-year survival rate for melanoma that has spread to the lymph nodes is thirty to forty percent.
The five-year survival rate is only twelve percent if the cancer has spread to other organs such as the liver,bones or brain.
Doctors believe too much sunlight can cause melanoma.
This is especially true for people who have light skin and were burned by the sun when they were young.
Some people are more likely than others to develop melanoma.
These include people whose family members had the disease.
They also include people who have a large number of moles on their bodies.
Doctors say people should protect their skin from the sun.
They should always wear a hat and protective clothing.
They should use a sun protection liquid.
Doctors also say people should examine their bodies often for any changes in moles or the presence of new dark areas.


逆向法巧学英语16.Asthma Study
New research suggests that very young babies who are with other children are less likely to suffer later from the breathing disease asthma.
Asthma is a disease in which small air passages in the lungs become temporarily blocked.
This causes difficulty breathing.
The disease affects an estimated seventeen-million Americans.
Every year,more than five-thousand people die of asthma in the United States.
It is the most common disease among children.
Day care centers are places where babies and children are cared for while parents are at work.
Researchers studied babies of different ages in day care centers.
They found that babies up to six months old gained the most protection from asthma.
They were only about half as likely to have asthma age thirteen as babies who did not attend day care until later.
Babies who entered day care after the age of six months also received some protection from asthma.
But they did not get as much protection as the younger babies.
Children who entered day care after the age of one showed no increased protection against the disease.
The study also found that children with two or more older brothers or sisters at home also had a lower risk for asthma.
Scientists believe early experiences with bacteria and viruses may help develop a baby's defense system against disease.
Scientists at the University of Arizona College of Medicine did the study.
They studied more than one-thousand children for more than thirteen years.
They also studied the substances in the children's environment that caused breathing problems.
American health officials say asthma cases have increased more than one-hundred percent since Nineteen-Eighty.
Experts say families with fewer children could result in the weakening of a child's defense against disease.
Scientists also say homes cleaned with products that fight bacteria could create the same problem.
The asthma study provides evidence for the idea that keeping a baby in an environment almost free of germs may cause problems later in life.
The study was organized by the National Heart,Lung and Blood Institute.
The results were published recently in the New England Journal of Medicine.


逆向法巧学英语17.Virus Suppresses
American and British scientists are using genetically changed viruses to seek and destroy cancer cells.
A new study shows that a changed cold virus injected into tumors shrinks them with lasting effects when combined with anti-cancer drugs.
The new treatment is showing promise in the treatment of head and neck cancers.
Almost five-hundred-thousand people suffer head and neck cancers every year.
Viruses and cancers work by invading tissue cells and taking control of them.
Using a process called gene therapy,scientists changed the genes of a virus so that it would target cancer cells.
The cancer cells are killed as the virus takes over.However,the virus does not damage normal cells.
The virus used in the study is called ONYX-Zero-One-Five.
Researchers developed it to destroy cells that have a changed tumor suppressor gene called P-Fifty-Three.
Changes in the P-Fifty-Three tumor suppresor gene are linked to up to seventy-percent of cancerous head and neck tumors.
Scientists report that the combination of the infected changed virus and anti-cancer drugs reduced head and neck tumors in twenty-five of thirty people tested.
They said cancerous tumors disappeared in eight people.
And they said in other people,the tumors shrank.
The researchers combined the virus treatment with powerful chemicals used in traditional cancer treatment.
These chemicals are called chemotherapy drugs.
The scientists say that ONYX-Zero-One-Five in combination with chemotherapy is more effective than either treatment alone.
They say tumors grew back in earlier studies that did not include both treatments.
But,researchers say none of the tumors treated with the combination treatment had grown after six months.
Scientists say the study is one of the most successful yet using gene therapy.
They also have begun testing the combination treatment on larger groups of people.
The study involved only people with cancer of the head of neck.
Yet the researchers expect the virus treatment to work on other tumors that contain changed P-Fifty-Three genes.
And they hope the treatment may be effective against cancers that have spread to other parts of the body.


逆向法巧学英语18.Diabetes Increas
A new report says the number of adult Americans with diabetes increased sharply during the Nineteen-Nineties.
Diabetes increased among adults of all races and age groups.
Diabetes is the name for several diseases with one thing in common.
There is too much glucose,or sugar,in the blood.
The disease develops when the body does not produce enough insulin or produces no insulin.
Or the disease develops when the body cannot use insulin.
Insulin is a hormone that is necessary to change sugar and other food into energy.
The report says the number of adult Americans with diabetes rose by thirty-three percent between Nineteen-Ninety and Nineteen-Ninety-Eight.
The largest increase was among people between the ages of thirty-nine.
There was a seventy percent increase in the disease in this age group.
Sharp increases also were noted among people in different ethnic groups.
Hispanic-American men and women had a thirty-eight percent increase.
Whites had a twenty-nine percent increase.Blacks had a twenty-six percent increase.
The report says sixteen-million adult Americans had diabetes in Nineteen-Ninety-Eight.
This is more than six percent of the population.
An additional eight-hundred-thousand Americans develop the disease each year.
Diabetes is the seventh leading cause of death in the United States.
It has been linked to health problems such as heart disease,stroke,high blood pressure,and kidney disease.
About ninety percent of people with the disease have Type Two Diabetes.
This from of diabetes can result from weight gain and a lack of activity.
The report says the percentage of Americans who are too fat also rose rapidly during the past ten years.
Experts say this is because Americans eat too much and do not exercise enough.
The report says the growing number of fat Americans will have a major effect on Type Two diabetes and other serious diseases in the future.
The new report is based on a telephone study that involved one-hundred-fifty-thousand people.
The Centers for Disease Control and Prevention released the study.It was published in the journal Diabetes Care.


逆向法巧学英语19.Mayapple Anti
American research scientists have found a new use for a wild plant commonly found in the United States.
The researchers say the mayapple plant produes a substance used for making a drug to fight cancer.
They say it can produce more of the cancer-fighting substance than anything else known to scientists.
The mayapple grows in the forests of the southern and central United States.
Many Americans consider the plant undesirable.
However,scientists have found that the mayapple produces a substance called podophyllotoxin.
Podophyllotoxin is used to produce the cancer drug etoposide.
Etoposide is used to treat lung cancer and cancer of the testicles.
It has been shown to restrict the activity of an enzyme necessary for the reproduction of cancer cells.
This prevents the spread of the disease.
Traditionally,podophyllotoxin has been collected from the roots of podophyllum emodi.
It is a wild plant that grows only in the Himalayan Mountains.
However,the plant has been declared endangered
Because too much of it has been collected in India.
Attempts to make copies of the cancer-fighting substance have proven costly.
Now,researchers from the United States Agriculture Department and the University of Mississippi have developed a way to get podophyllotoxin from the mayapple plant.
The researchers believe that both the mayapple and podophyllum emodi produce the substance as a form of protection against insects and other plant-eating creatures.
The plants store the substance until they are attacked.
The American researchers say their method is successful because it makes the mayapple think it is being attacked.
This results in the release of large amounts of podophyllotoxin.
They say their system to remove podophyllotoxin from the mayapple is fast,effective and low cost.
The researchers say the mayapple plant provides a plentiful and renewable supply of the substance.
And they add there may be increased demand for the mayapple plant as a crop if the method becomes widely used.


逆向法巧学英语20.Osteoporosis
A new study shows that a drug that helps women with osteoporosis also helps men.
This disease makes bones thinner and weaker.
It increases chances that the bones will break.It also leads to loss of height.
Ten-million people in the United States have osteoporosis.Two million of them are men.
Women with osteoporosis have been treated successfully with drugs.
But there currently is no treatment approved for general use in men.
The New England Journal of Medicine reported the research.
The study involved two-hundred-forty-one men with osteoporosis.
They were aged thirty-one to eighty-seven.One-hundred-forty-six men received the drug Fosamax each day.
Ninety-five of the men received a pill containing no medicine.
Everyone in the study took Vitamin D and calcium.
The men who took Fosamax had a seven-percent increase in the thickness of the bones of their backs.
They had a three-percent increase in the thickness of their hipbones.
They had a two-percent increase in bone density in their bodies in general.
Men who took the false drug had a two-percent increase in thickness of the bones of their backs.
However,they had no increase in their hipbones.Nor was there general improvement in their whole bodies.
During the two years of the study,one-percent of the group taking Fosamax broke their back bones.
But seven percent of those who took the false drug suffered broken bones in their back.
The lead study researcher was Eric Orwoll.
He works for the Oregon Health Sciences University in the northwestern city of Portland,Oregon.
Doctor Orwoll says scientists have thought of osteoporosis as a women's disease.
Many older women suffer bone loss after their menstrual periods stop.
He says scientists have not considered that men also suffer from osteoporosis.
Generally,fewer men than women get the disease because men have larger and stronger bones.
However,men are more likely to get osteoporosis if they smoke cigarettes or drink a great deal of alcohol.
They also are more likely to get the disease if they do not exercise,or if they take drugs known as steroids.
The company that makes Fosamax now is seeking government approval of the drug for men with osteoporosis.


逆向法巧学英语21.Genetically
A new study has found that pollen from genetically-changed corn plants can harm Monarch butterflies.
Research scientists at lowa State University confirmed results of an earlier study that examined the environmental effects of a product called B-t corn.
However,a group that represents the genetic engineering industry disputes the findings.
B-t corn was developed by a process of genetic engineering.
Genetic engineering is the technology of changing the genes of living things.
The changed gene directs the plant or other organism to do things it normally does not do.
B-t corn seeds were given a gene from a bacterium that produces a poison.
The poison kills harmful insects that eat the corn plants.
The insects cause an estimated one-thousand-million dollars in damage to corn each year.
American farmers began using B_t corn four years ago.
The plants have helped increase crop production.
They also have reduced the need for farmers to use chemicals to kill harmful insects.
Today,about one-third of all corn grown in the United States is B-t corn.
Many of the plants are grown in areas where monarch butterflies live.
Last year,Cornell University researchers reported B-t corn might be killing the caterpillars that turn into monarch butterflies.
They said pollen from the corn could blow onto other plants the insects eat.
Pollen is a reproductive substance made by plants.
Monarch caterpillars feed only on milkweed plants.Milkweed commonly grows in or near cornfields.
The Iowa State researchers collected leaves from milkweed growing near cornfields.
Pollen had blown onto the leaves.They fed the leaves to monarch caterpillars in the laboratory.
The caterpillars that ate leaves with pollen from traditional corn survived.
However,about twenty percent of the caterpillars that ate leaves with B-t pollen died.
The Biotechnology Industry Organization said twenty other unpublished studies dispute the findings.
The group says those studies have shown that B-t corn has little effect on Monarch butterflies.
The Environmental Protection Agency also is studying the possible effects of B-t corn on the environment.
The agency has announced that permits to sell B-t corn seed will be extended for another year.


逆向法巧学英语22.World Food Prize
Two scientists who worked for years to develop high-protein corn have won the World Food Prize for this year.
Evangelina Villegas of Mexico and Surinder Vasal of India will be honored next month at ceremonies in the United States.
The World Food Prize Foundation presents the award each year to honor people who have improved the quality of world food supplies.
Mizz Villegas is the first woman to be honored in the fourteen years since the World Food Prize was established.
The two scientists did their work at CIMMYT,the International Maize and Wheat Improvement Center in Mexico.
The World Food Prize committee says they have worked together for the past thirty years to develop quality protein maize.
The new maize,or corn,contains a gene that increases the amount of protein in the plant.
American scientists at Purdue University in Indiana first identified the gene in Nineteen-Sixty-Three.
However,early efforts to produce this kind of maize failed.
The plants were difficult to grow.Also,insects and disease often attacked them.
Mizz Villegas and Mister Vasal successfully used a method known as cross-breeding.
They used different kinds of maize to produce a stronger,more successful plant.
The scientists found the high-protein maize could be produced at the same rate as traditional maize.
And the new plants had two times the amount of two important proteins normally found in other maize.
Quality protein maize is currently being tested in China,Ghana,Mexico,Vietnam and fourteen other developing countries.
Maize is an important feed grain for farm animals.
It also is a major food for hundreds of millions of people.
In Africa and Latin America,mothers commonly give a substance made from maize to their babies.
The World Food Organization says people with diets based on normal maize do not get enough protein.
W-H-O officials blame a severe lack of protein for the deaths of as many as five-million young children each year.
The International Maize and Wheat Improvement Center has done studies of the new maize in Peru and Colombia.
The studies have shown that a controlled diet with the high-protein maize can help restore the health of many children.
The group reports similar results in a village in Ghana and in studies in the United States.


逆向法巧学英语23.Lasker Awards
Six scientists have won this year's Albert lasker Medical Research Awards.
The Albert and Mary Lasker Foundation presented the awards last week in New York City.
Harvey Alter and Michael Houghton shared the award for medical research involving patients.
Doctor Alter led the team that discovered the virus that causes hepatitis B.
He works at the National Institutes of Health,near Washington,D.C.
Doctor Alter and Doctor Houghton developed methods to test blood for hepatitis.
This ended the risk of people developing hepatitis after receiving blood from other people after an accident or operation.
This risk decreased from thirty percent in Nineteen-Seventy to almost no risk today.
In Nineteen-Eighty-Nine,Doctor Houghton led scientists who discovered the virus that causes another kind of hepatitis,hepatitis C.
He works at the Chiron Corporation in Emeryville,California.
Three scientists shared the Lasker award for basic medical research.
One is Alexander Varshavsky of the California Institute of Technology in Pasadena.
The others are Aaron Ciechanover and Avram Hershko of the Technion-Israel Institute of Technology in Haifa,Israel.
The three discovered the human body's method of destroying proteins.
The process of protein destruction controls normal cell growth and division.
When this process does not work properly,diseases like cancer can result.
Scientists also are investigating a possible link between this process and diseases of the body's defense system.
Sydney Brenner of the Molecular Sciences Institute in Berkeley,California received a Lasker award for special achievement in medical science.
The foundation honored him for fifty years of creative work in biomedical science.
For example,Doctor Brenner's team studied the roundworm to show the birth and death of every cell in a living animal.
Doctor Brenner also performed research that took the first step toward understanding human genes.
He also helped calm fears that research on genetic engineering would create dangerous organisms.
To do this,Doctor Brenner drank bacteria that had been genetically weakened.
The experiment proved that such substances would not threaten the public.
The results were very important to the study of several deadly viruses,including the one that causes AIDS.


逆向法巧学英语24.American
Our VOA listener question this week comes in an e-mail from China.Zhao Hengyuan asks which animals represent the-two main American political parties,and why.
The two main American political parties are the Democrats and the Republicans.
They are represented by a donkey and an elephant.
The reason comes from political cartoons.These are drawings that express opinions about political parties,issues or candidates.
Perhaps the most famous political cartoonist in American history was Thomas Nast.
He lived more than one-hundred years ago.
Thomas Nast used his drawings to show dishonesty and the illegal use of power in government.
His cartoons helped create public pressure on elected officials.
In Eighteen-Seventy,newspapers supporting the Democratic Party denounced a former Republican cabinet member.
Thomas Nast drew a cartoon in protest.He called it"A Live Jackass Kicking A Dead Lion."
The dead lion represented the cabinet member who was no longer in power.
The jackass represented the Democratic Party."Jackass"is an old slang word for someone who is stupid or foolish.
It is also another work for donkey.The image of the donkey had been used many years earlier.
Democratic President Andrew Jackson usedit as his personal political symbol,after his opponents called him a jackass.
Then it was used,sometimes,to mean the whole Democratic Party.
It became established as the party symbol when Thomas Nast used it to represent the Democrats.
Thomas Nast himself created the elephant as a symbol of the Republican Party.
He first used it in a cartoon in Eighteen-Seventy-Four.
And he continued to use the elephant to represent the Republicans in many other cartoons.
Soon,everyone thought of it as the Republican Party symbol.
Today,after more than one-hundred years,the donkey and the elephant continue to represent America's two major political parties.


逆向法巧学英语25.Mount Rainier
STEVE EMBER:This is Steve Ember.
SHIRLY GRIFFITH:And this is Shirley Griffith with the VOA Special English program EXPLORATIONS.
Today we tell about two areas that are popular with visitors to the United States.
We tell about one of the most important places in the history of the American Revolution.
It is Valley Forge National Historical Park,in the eastern state of Pennsylvania.
And we tell about a place of fierce beauty.It is Mount Rainier National Park in the northwestern state of Washington.
STEVE EMBER:The American Indians who lived in the northwest called the great mountain"Takhoma."
One tribe said it was a female monster that would eat people.
Other old stories among the Indians said the mountain could produce huge amounts of fire.
In Seventeen Ninety-Two,British explorer George Vancouver became the first European to see the huge mountain.
He named it after a navy friend,Captain Peter Rainier.
Today the people who live in the northwestern city of Seattle call it"The Mountain."
Mount Rainier is almost one-hundred kilometers from Seattle.
Yet it can be seen from almost any place in the city.
The beautiful,snow covered mountain seems to offer the city its protection.
SHIRLY GRIFFITH:The Mountain's offer of protection is false.Mount Rainier is not just a mountain.It is a sleeping volcano.
Steam and heat often rise from the very top of the huge mountain,causing snow to melt.
Mount Rainier is four-thousand-three-hundred-ninety-two meters all.
Its top is covered in snow all year.More than twenty-five thick rivers of ice called glaciers cover a lot of the mountain.
In some areas,these glaciers are more than one hundred meters thick.
STEVE EMBER:Mount Rainier always has been a popular place to visit.
Many people go to enjoy the beautiful forests that surround the mountain.
Others go to climb the mountain.
Hazard Stevens and Philemon Van Trump became the first people known to reach the top of Mount Rainier.
They reached the top in August of Eighteen-Seventy after a ten hour climb through the snow.
In Eighteen Ninety,a young schoolteacher became the first woman to reach the top.
Her name was Fay Fuller.For many years after her successful climb,
she wrote newspaper stories asking the federal government to make Mount Rainier a National Park.
Many people who visited the mountain also wanted it to be protected forever by the government.
On March Second,Eighteen-Ninety-Nine,President William McKinley singed a law that made Mount Rainier a national park.
It was the fifth national park established in the United States.
SHIRLY GRIFFITH:Today,National Park Servic e experts say about tenthousand people climb the huge mountain each year.
Less than half that number reaches the top.The mountain can be extremely difficult to climb.
Severe weather is possible at almost anytime.Snow and ice cover parts of the mountain all year.
More than fifty people have died trying to climb Mount Rainier.
Mountain climbing experts often use it as a difficult eat for persons who want to climb some of the world's highest mountains.
STEVE EMBER:You do not have to climb the huge mountain to enjoy Mount Rainier National Park.
More than two-million people visit the park each year.
Many walk on the hundreds of kilometers of paths.
The paths lead through flat meadows filled with wild flowers and up through forests of large old trees.
Other visitors drive around the park to experience its natural beauty.
They often see black tailed deer,elk,and mountain goats.
The park is large.It is almost one-hundred-thousand hectares.
Many lakes,rivers,roads,two hotels and six camping areas are inside the borders of the park.
SHIRLY GRIFFITH:Experts agree that Mount Rainier will become a very active volcano at sometime in the future.
They say the real problem is that they do not know when.
They also agree that the great heat produced by an explosion of the volcano would melt the ice rivers that are part of the mountain.
This could happen in only a few minutes.
They say the melting ice would produce flowing rivers of mud and rock.
People who live in the southern part of Seattle and in the city of Tacoma,Washington would be in danger.
Expets carefully study the great mountain.
They hope to be able to warn of any dangerous change.
But for now,the great mountain provides a safe and beautiful place to visit in the Northwest area of the United States.
STEVE EMBER:A very different kind of national park is found in the eastern state of Pennsylvania.
It is called Valley Forge National Historical Park.It is near the city of Philadelphia.
Valley Forge also is a beautiful place.
Within the park are many different kinds of trees and flowers,huge areas of green grass,a beautiful,slow moving river.
You can see many deer.Often you can come very near them.
Deer do not run away because they are used to seeing people in the park.
It is not the natural beauty that made Valley Forge a National Historic Park.
It is what happened there.Many other places were important in the American War for Independence,but no other place is so filled with suffering.
No battle was fought at Valley Forge.
Yet,more than two-thousand soldiers of the small American army died there.
They died of hunger,disease and the fierce cold in the winter of Seventeen-Seventy-Seven and Seventeen-Seventy-Eight.
It was also at Valley Forge where the men of this small army learned to be real soldiers.
SHIRLY GRIFFITH:What happened at Valley Forge began in August of Seventeen-Seventy-Seven.
A British force threatened to capture the American capital at Philadelphia.
The American commander,General Georal George Washington,moved the army to defend the city.
A battle was fought at a place called Brandywine and another at Germantown.
The British forces won those battles and occupied Philadelphia.
By the month of December,General Washington needed to find a place his small army could easily defend.
He chose Velley Forge.More than fifteen centimeters of snow fell only a few days after the army arrived.Ice covered the rivers.
The soldiers began building very small wooden houses called log cabins.
They would build more than one-thousand of these small homes.
STEVE EMBER:The fierce winter was only one of the many problems faced by the American army.
Many of the soldiers had no shoes.
Most had no winter clothing.All suffered from a severe lack of food.
Then,several diseases struck.Typhoid,dysentery and pneumonia were among the diseases that spread through the army.
Most of the soldiers became sick.Many died.
General Washington wrote letters to Congress asking for help.
He asked for money to buy food and clothing.But Congress had no money to give him.
Several things happened to change the small army during that long and terrible winter.
General Washington knew the army had been defeated in the past because of a lack of real training.
A man named Baron Friedrich von Steuben had recently come from Europe.
He was an expert at training soldiers.
So,each day during the terrible winter,Baron von Steuben taught the men of the American army to be soldiers.
He also taught them something very important.He taught them to believe in themselves.
SHIRLY GRIFFITH:As the winter passed,the army slowly changed.New troops arrived.
New equipment arrived.An alliance with France brought guarantees of military support.
The men who survived that terrible winter were no longer a group of armed citizens.
They were well trained soldiers who no longer feared the enemy.
When the American army left Valley Forge on June Nineteenth,Seventeen-Seventy-Eight,the soldiers took with them the spirit that had helped them to survive.
The War for Independence would continue for another five years.Terrible battles were yet to be fought.
However,the men who had survived the winter in Valley Forge knew they could win.They did.
STEVE EMBER:Today,you can visit the area where Baron von Steuben trained the soldiers of the American Revolution.
You can watch a movie about the American soldiers struggle to survive that long ago winter.
You can see examples of the small log homes the soldiers built.
You can walk on paths along the remains of the defense system and the officers'headquarters.
And you can feel the spirit of Valley Forge.


逆向法巧学英语26.Bill Gates
Our VOA listener question this week comes in an e-mail from Italy.
Matteo Trotta asks how American Bill Gates became the richest person in the world.
And,he asks about Mister Gates'recent legal problems.
Bill Gates is the head of the Microsoft Corporation,near Seattle,Washington.
Last week Microsoft celebrated its twenty-fifth anniversary.
Bill Gates is forty-four years old.
He says he always believed that computers would become the most important tools ever invented.
He became interested in computers when he was thirteen.
After high school,Bill Gates attended Harvard University in Cambridge,Massachusetts for one year.
He left college and formed the Microsoft Company in Nineteen-Seventy-Five.
He began the company with just three workers.
Today,Microsoft has more than thirty-thousand employees around the world.
In Nineteen-Eighty-One,the I-B-M Company began using Microsoft products as part of the operating system in all its computers.
Microsoft now makes hundreds of products for the computer industry each year.
As the Microsoft Company grew,so did the wealth of Bill Gates.
His shares in the company are worth about fifty-five-thousand-million dollars.
Mister Gates has promised to give away most of his money.
He has given hundreds of millions of dollars to combat disease and improve health for people around the world.
For example,he gave forty-five million dollars to the Harvard University Medical School.
The money will be used to study a deadly form of the disease tuberculosis,which can not be cured by drugs.
Bill Gates also says he is very interested in world health issues like AIDS and malaria.
And he wants to do more to improve the health of mothers and children in developing countries.
Many computer industry experts are not happy with Bill Gates and Microsoft.
They say the company is trying to control the computer industry.
Smaller computer companies say it is almost impossible to compete against Microsoft.
The United States government brought legal action against Microsoft Corporation.
The government says Microsoft uses unfair and illegal business dealings to compete against smaller companies.
A judge ruled that Microsoft should be divided into two smaller companies.
Bill Gates has appealed the decision.It could still be some time before a final decision is made about Microsoft.


逆向法巧学英语27.PeruFujimori
President Alberto Fujimori of Peru has called for new elections and said he will not be a candidate.
Mister Fujimori made the announcement after a top adviser created a political crisis.
It began with a videotape.
The tape appeared to show the adviser offering money to an opposition member to join Mister Fujimori's political party.
The adviser was Vladimiro Montesinos,chief of Peru's National Intelligence Service.
The president ordered the agency"deactivated."
Mister Montesinos has strong links to the army.
For days the powerful military said nothing about the situation.
This silence worried people.Peru has a history of military overthrows.
But on Thursday the armed forces expressed support for Mister Fujimori.
Critics condemned Mister Montesinos and demanded his arrest.
They also demanded that President Fujimori immediately resign.
But the president told a crowd of supporters that he will contine to govern until July twenty-eighth.
Mister Fujimori also held a news conference.
He told reporters that he had a surprise for them about what he is going to do in Two-Thousand-Six.
The reporters took this to mean that he may again seek office.
They asked President Fujimori if the United States government had urged him to resign.
He said there had been no such suggestion.
The president did not answer questions about Mister Montesinos.
Peru's justice minister said Mister Montesinos would answer to the justice system.
Opposition leaders say there must be a full investigation into recent government activities.
And they demanded that Mister Montesinos face trial.
Late in the week,anti-government demonstrators held noisy protests outside the presidential palace in Lima.
Political experts have both praised and criticized the administration of Alberto Fujimori over the past ten years.
More importantly,they say,his administration has ended the years of terrorism that harmed Peru.
And he helped to lower the inflation that had severely damaged the economy.
Political experts say Mister Fujimori has improved the economy by decreasing import taxes and easing government controls on business.
Experts say increased investment and economic growth helped to strengthen democracy in Peru.
But critics say President Fujimori's plans for economic growth have now slowed.
They also say his administration is not democratic.
They say he has acted illegally in the past and has become a dictator.
Observers in Peru say just what President Fujimori will do in the coming weeks is not clear.
They say he has survived more than one political crisis,and may do so again.


逆向法巧学英语28.Foreign Students
HOST:Today we begin a series of reports about how foreign students can prepare to study at a university or college in the United States.
Shep O'neal tells us about the first steps.
A copy of this script can be found on the Special English web page at the address www.voa.gov/special.
ANNCR:Experts agree.The most important advice is to plan early if you want to study at a college in the United States.
In fact,the experts say to begin planning at least two years before you want to start your studies.
You might begin by talking with people who have studied in the United States.
Their experiences could save you time and effort.
Then visit an American educational advising center.
There are more than four-hundred such offices throughout the world.
The Public Affairs Office at the United States Embassy in your country can tell you where the nearest one is.
There you will find and educational advisor to answer your questions and offer information.
Every center should have information about American colleges.
Some educational advising centers have computer programs to help.
One example is a CD-ROM program called US Academic Explorer:A Guide to Higher Education in the United States.
The program shows an imaginary American college.
It tells about each building,such as the student center and the library.
It answers questions about food,housing,health care,social customs and banking.
It even shows a day in the life of a student.
The CD-ROM also provides information about higher education in the United States.
It shows a national map.And it includes interviews with international students.
The students talk about their American college experiences.
They discuss English language requirements,money,personal safety,making friends,dating and other subjects.
You can hear one student discuss all these issues or hear many students answer just one question.
The CD-ROM does not contain information about any one American college or university.
The advising center should have books to provide that kind of information.
Many centers also have computers that can be used to search for information about American colleges on the World Wide Web.
This computer information describes each college's programs and gives an address where you can write or e-mail to get more information.
Next week,we will explain how American higher education is organized.
HOST:This week on our series for foreign students,we explain the structure of university education in the United States.
This information can prevent costly mistakes.
You would not want to begin studying at a school that could not provide the degree you need.
Remember,a copy of this script can be found on the Special English web page at the address www.voa.gov/special.
Shep O'neal has information you will need as you consider American universities.
ANNCR:Studying in the United States does not mean choosing a university that offers only the traditional four-year degree.
You may want to consider a school that offers a certificate program.
These programs are one year or less of training in areas such as office work,computer programming or automobile repair.
When you complete the program,you receive a certificate stating the skills you have learned.
Make sure that any program you want to enter offers a certificate that is accepted by employers in your country and in the United States.
You may also choose a two-year junior college or community college.
Such programs lead to an Associate degree.
Some two-year programs prepare you for skilled trades or technical jobs in such areas as electronics and building.
Many colleges and universities accept community college work as the first two years toward a four-year Bechelor's degree.
And a year at a community college costs much less than at a traditional four-year-college.
Four-year college programs lead to a Bachelor's degree.
During the first two years,you generally take subjects such as English,history,mathematics,science and languages.
What you take the last two years depends on your major area of study.
If you already have a college degree,you may be considering an American graduate school.
You must continue your education in graduate school if you want to be a medical doctor,lawyer or college professor.
A Master's degree usually takes two or three years of full time study.
A Doctoral degree,or Ph.D.,takes three to six years.
Some colleges,universities,hospitals and laboratories also offer a chance to do scientific research.
You may want to communicate with one of them to see if you can do research in a subject in which you are interested.
Next week,we will discuss getting your higher education on a computer.
HOST:Today we continue our series about how foreign students can attend an American college or university.
Remember,this script can be found on the Special English web site at www.voa.gov/special.
One way to earn a degree at an American college is to stay at home and use a computer.
But you should find out if such a degree is recognized in your country before you decide to get an education online.Shep O'neal has more.
ANNCR:American universities have been offering classes online through computers for a number of years.
Researchers say that seventy-five percent of all American universities will offer online work by the end of this year.
Students who have taken online classes say they like them because they do not have to travel to a building at a set time to listen to a professor.
Professors say they have better communication with students through e-mail notes than they do in many traditional classes.
Now,some newly created colleges are offering academic degrees online.
One is Jones International University in Englewood,Colorado.
It offers both bachelor's degrees and master's degrees.
It has about one-hundred students,but is seeking many more.
The University of Phoenix in Arizona has been offering online degress since Nineteen-Eighty-Nine.
It has more than twelve-thousand students.
Officials say they try to provide students with a social experience as well as an educational one.
For example,in some programs,groups of the same six students progress through all their classes together.
They communicate by computer.
Another online school is UNext dot com or Cardean University,near Chicago,Illinois.
It began operations this past summer.
It is offering business education and training now,but has plans to expand.
Cardean University uses a problem-solving method of teaching.
Students attempt to solve real problems in their classes online instead of reading information.
Anyone with a computer can find information about these schools and others on the Internet by using a web browser.
Type the name of the school and the browser will give you its address.
Each college will tell you about its programs,costs,and many other important facts.
Experts advise,however,that you do not give money to any school that says you can get a degree without doing any work.
These are illegal operations.
HOST:We continue our series about how foreign students can attend college in the United States.
Remember,this script can be found on the special English Web page.
The address is www.voa.gov/special.
We have already explained how to begin your search at an education advising center.
And we told about studying online by computer.
Now,it is time to make a list of American colleges and universities that most interest you.Steve Ember has more.
ANNCR:Be sure to choose more than one college.
Directors of foreign student admissions at American colleges say each student should apply to at least three schools.
First,you must get applications from the colleges.
An application is a form you must complete if you are asking the college to admit you as a student.
You should request applications at least eighteen months before you want to begin studying in the United States.
You can find the address of the admissions office in the catalog of each college.
A catalog is a book that tells all about the school.
You can also find such information on the college's Web page on the Internet computer system.
For example,the Ohio State University provides application forms on its Web pages.
You can answer all the questions on the computer and e-mail the application directly to the university.
Or you can copy the application forms to your computer,print them,complete the questions and mail them.
Or you can fill out a computer form to ask the university to send you an application in the mail.
If you cannot use a computer at all,write a letter to the address given in the catalog.
Ask the college to send you the international admission application.
Write the letter clearly.List the schools you have attended,and any degrees you already have.
Explain what you want to study and what degree you are seeking.
Explain when you want to begin studying.
You will receive a letter or application from each school.
Complete the application and send it back.Then you must wait until the college makes its decision.




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