职称英语阅读理解2013理工印全

第六篇Making Light of Sleep

All we have a ……

1 .The clock located inside our brains is similar to our bedside alarm clock because

it controls when we wake，when we eat and when we sleep.

it has a cycle of 24 hours.

it is a cycle also called circadian rhythm.

it can alarm any time during 24 hours.

2. What is implied in the second paragraph?

Young children's biological clock has the same rhythm with that of the teenagers.

People after puberty begin to go to bed earlier due to the change of the biological clock.

Children before puberty tend to fall asleep earlier at night than adolescents.

Teenagers go to bed later than they used to due to the light from the computer screen.

3. In the third paragraph the author wants to tell the reader that it is natural for teenagers to stay up late and get up late. staying up late has a bad effect on teenagers' ability to think and learn.

during puberty most teenagers experience a kind of gray cloud. it is hard for teenagers to get out of bed in the morning.

4. Which of the following statements is NOT true according to the fourth and fifth paragraphs?

Our biological clock resets itself automatically.

light gets through our eyes and resets our biological clock.

Our internal clock as well as the alarm clock can be reset automatically.

Our internal clock，like the alarm clock，can be reset.

5. According to the last two paragraphs，what did the previous researchers think about the human eye's light-sensing system? The human eye had two light-sensing systems.

The human eye had one light-sensing system.

The human eye could sense the light of day more quickly than the dark of night.

The human eye could reset our internal clocks in accordance with the alarm clocks.

第十九篇

Graphene's Superstrength

Big technology comes in ……

1.What would change the future of electronics according to engineers?

Big technology. Creative ways.Graphene.Both A and B.

2. According to the second and third paragraphs，what is true of graphene?

It can be used to make paper.

It is possible to see it with our naked eye.

It is easy to find graphene.

It is possibly the thickest material in the world.

3.Which of the following can be used to replace the word “apply”in paragraph 4?

request. polish. use. put.

4.Which of the following is NOT meant in the last two paragraphs?

Graphene is made of graphite，one of the softest materials in the world.

Graphite is made of layers of graphene，the thinnest material in the world.

When we get to the thinnest possible layer of graphite，we find graphene.

With a pencil，a sheet of paper and a piece of adhesive tape，we can find graphene.

5. Graphene's superstrength lies in the fact that

It is the thinnest material in the world.

It is made of the most abundant elements in the world.

It can help to make electronic components smaller.

It helps engineers to produce more sensitive electronic products. *第三＋八篇"Life Form Found" on Saturn's Titan Scientists say they have ……

1 .What have scientists found about Saturn?

They have found a new moon orbiting Saturn.

They have found methane-based life on Saturn.

They have found methane-based life on Titan.

They have found earthlike life on a Saturn's moon.

2. What do scientists say about Titan?

There are life clues there. There is acetylene there.

Water on Titan exists in the form of ice.

Rivers and lakes there contain life formals.

3. To date, scientists have not yet detected this form of life.(paragraph 5)What does "this form of life" refer to?

Water-based life. Methane-based life.

Liquid-water-based microorganisms. Gas-based life.

4. What can be inferred from what Allen said?

Scientists have different arguments over whether there is life on Titan.

Scientists all agree that there is life on Titan.

Scientists all suggest that a biological explanation is reasonable. Scientists all agree that a non-biological chemical reaction is a possible explanation.

5. Which of the following can replace the title of this passage? Earthlike Living Beings Found on Titan.

Finding of One More Moon of Saturn.

Titan, a New Satellite Found.

A different Life Form, a Possibility.

*第四十篇Teaching Math, Teaching Anxiety

In a new study……

1. What is the result of the research at the University of Chicago, according to the first paragraph?

Girls comfortable with their own math skills are better than boys at math.

Girls uncomfortable with their own math skills are not as good as boys at math.

Female teachers' math skills have influence over girl students' math skills.

Female teachers' confidence in their math skills is related to girl's math skills.

2. What is implied in the third paragraph?

Math teachers, like math learners, do not like the subject due to its difficulty.

A difficult subject like math may affect teachers' confidence in teaching the subject.

Teachers are more anxious teaching math than their students learning math.

Math is so difficult that no teachers like to teach it.

3. According to the experiment, those teachers were probably

anxious about math when they felt

nervous memorizing the numbers of a sales receipt.

helpless saving the numbers of a sales receipt.

uneasy reading the numbers of a sales receipt.

hopeless filling in the numbers of a sales report.

4. The sixth paragraph tells us that the research findings

prove a strong link between female teachers' math anxiety and their female students' math achievements.

show that male students are less likely to be affected by their math anxiety than female students.

provide strong evidence that math superstars are more likely to be males than females.

discover a strong link between teachers' math anxiety and their students' math achievements.

5. David Geary thinks that

the study is interesting but it is based on unreliable research process.

the research results need to be retested based on a larger sample.

the research results need to be reinterpreted to be meaningful. the study is well based and produces significant results.

+第四＋五篇Small But Wise

On December 14,NASA ……

1 .What is so special about WISE?

It is small in size but carries a large camera.

It is as small as a trashcan.

Its digital camera can help astronomers to see the unknown space.

Never before has a telescope carried a digital camera in space.

2. Which is NOT the synonym for the word "snap" in the third paragraph?

make shoot take photograph.

3. The camera on WISE

is no different from an ordinary camera.

does not see infrared radiation while the ordinary camera does. catches the infrared radiation while the ordinary camera does not.

reflects light that human eyes can see.

4. Which of the following is NOT correct about "asteroids" according to paragraph 7?

Asteroids float through space giving off visible light. Asteroids do not reflect light that reaches them.

It is difficult to take asteroids' pictures by ordinary cameras, The WISE telescope can take pictures of asteroids

5.What is implied in the last paragraph?

Brown dwarfs give off visible light.

Brown dwarfs give off infrared radiation.

Brown dwarfs are power stars like the sun.

Brown dwarfs are impossible to see with the WISE telescope. +第四十六篇

Ants Have Big Impact on Environment as "Ecosystem Engineers"

Research by the University……

1 .Why are ants compared to ecosystem engineers?

Because they build their own nests.

Because they collect food.

Because their activity affects the environment.

Because they are predators. 2. As predators, ants

prey on small as well as large animals.

collect nutritious food from the soil

collect food as decomposers.

prey on species much higher up the food chain.

3. Dir Sanders' study centered on how ants

can manage to thrive in huge numbers.

defend their resources and territory against other predators. attack those invading animals for survival.

produce such a big impact on the environment.

4. What does paragraph 6 tell us?

Ants bring about a negative influence to an area when their population is small.

Ants bring about a positive influence to an area when their population is small.

Ants' predation counteracts the positive influence they may have on an area.

At higher density, ants produce a positive influence on an area.

5. What still remains unclear about ants, according to the last paragraph?

What roles do ants play in the ecosystem in which they live? How do ants affect the animal diversity in a given ecosystem? How do human activities affect ants' influence on a given ecosystem?

How do ants alter the physical and chemical environment?

In a finding that may speed efforts to conserve oil……1．Which of the following is closest in meaning to the word "sparked" appearing in paragraph 2?

flashed stimulated changed ended

2．The term "a bell shaped curve" appearing in paragraph 2 indicates that global oil production will

take the shape of a flat curve．B keep growing．

keep declining.

start to decline after global oil production peaks.

3.Which of the following is NOT true of the Hubbert model?

It successfully predicted that oil production peaked in the U．S．in l 970．

It has been used to predict oil production in many countries．

It is insufficient to explain oil production cycles in some countries．

It provides a very realistic and accurate oil production. 4．What is the major achievement of the new study mentioned in the last paragraph?

It predicts global oil production will peak in 2014.

It predicts oil production will decline in 47 countries.

It confirms further the effectiveness of the Hubbert model.

It discovers a new trend of Worldwide oil production.

5. Who develop the new version of the Hubbert model? American scientists.

Kuwaiti scientists．

British scientists.

Scientists of 47 major oil-producing countries.

What do chicken pox……

1．According to the first paragraph，people try to

kill microorganisms related to chicken pox，the flu，etc．keep themselves away from viruses because they are invisible．stay away from viruses because they are causes of various diseases.

cure themselves of virus—related diseases by taking medicines．2 What is Belcher's team doing at present?

It is finding ways to get rid of viruses．

It is mass—producing microbatteries．

It is making batteries with viruses．

It is analyzing virus genes．

3 What expression below is opposite in meaning to the word "shrink" appearing in paragraph 5？

Broaden Spread Extend Expand

4. Which of the following is true of Belcher's battery mentioned in paragraph 6？

It is made of metal

It is a kind of watch battery．

It can only be seen with a microscope

It is a metallic disk with viruses inside it．

5. How tiny is one battery part?

Its width is one tenth of a hair

It equals the width of a hair

It is as thin as a piece of paper

Its width is too tiny to measure

Invisibility cloaks would have remained……

1．What is true for metamaterials?

They will always remain in science fiction

They are already a reality

They are nonexistent in nature

Scientists begin to use them to build invisible cloaks

2．A hyperlens is a more powerful tool than a traditional lens as it can allow scientists to see small things

as it can help photographers to capture images far away

even if it is made of ordinary materials

as it can help scientists to see even the wavelengths of visible light

3．Scientists at the Polytechnic University of Valencia try to invent

an acoustic cloak that can shuffle waves of light

an invisible cloak that can shuffle waves of sound

an acoustic cloak that can shuffle waves of sound

a cloak that is made of materials found in nature 4．According to Sdnchez—Dehesa,

it is of great possibility to build an acoustic cloak soon．

it is possible to build an acoustic cloak in theory but far from reality．

it is totally impossible to build an acoustic cloak.

it is theoretically impractical to build an acoustic cloak 5．What ways are some scientists looking into to protect the island and oil；rig from tsunamis? (Read the last paragraph Surround them with metamaterials as protective shields Stopping the tsunami with metamaterials hours before it reaches them

Building them with larger metamaterials to keep away tsunamis Using the equipment made of metamaterials to forecast arrival of a tsunami

The Ford motor company's1 abandonment ……

They have given up producing electric cars.

will not be the main transportation vehicles in the future. Toyota and Nissan.

run more miles than petrol driven cars.

The legislation will allow more low-emission lo be produced. Understanding how nature responds to climate …….

to collect data of the life cycle of living things.

To send their research observations to a professional database.

a citizen scientist.

Only experts can participate in it.

To investigate how plants and animals will respond as the climate changes.

1.2 million road deaths worldwide occur ………

They focus their research on safety and new fuels.

because drivers make mistakes.

Windscreens mat can help drivers to improve their vision.

To call for help when me car gets jammed in the traffic.

It will take some time before robotic drivers can be put to practical use.

Coffee lovers beware. Having a quick "pick-me-up" …coffee is a stimulant.

Caffeine halves the body's levels of sleep hormone.

Different effects of caffeinated coffee and decaf on sleep. Caffeine drinkers produce less sleep hormone.

we should not drink coffee after supper.

Using enzymes commonly found in living cells,……

When the technology of a new type of fuel cell is suitable for mass production.

They had trouble keeping enzymes in fuel cells active.

when the enzyme oxidizes the glucose from a sugary liquid that goes through a pocket.

Their limited power generation capacity is a good beginning.

It will take some time before die new fuel cells can be used in popular products.

Some 300 meters up, near the Eiffel Tower's……..

Tourists of all nationalities come to scribble on the cold iron of the tower.

Visitors prefer wasting time scribbling to enjoying the view. He climbed 747 steps up the tower in 19 minutes and 4 seconds. Conducting research in various fields.

Visitors can imagine freely what the tower represents.

Even ancient Egypt's mighty pyramid builders were……Because even they were unable to rescue their civilisation. Change of climate.

The White Nile and the Blue Nile are branches of the River Nile.

immediately after a period of drought.

"damaging".

Young female chimps are faster and better learners……Because young female chimps begin to study their mothers earlier.

Vegetation.

Females could get out more termites with every dip.

It will make them good fighters and hunters in the future. Adult chimps hunt monkeys while young chimps fish for termites.

Companies are paying up to SI0,000 to register domain……the company Network Solutions.

the US government.

a registrar.

It must pay up to $10,000 or a nonrefundable deposit.

The registration fee for a domain name on the Internet.

In January, 2003, the eastern two-thirds of the United…….

The temperature in the United States except the South dropped below the freezing mark.

Parts of interior South Florida.

he was caught by the sudden cold.

' wanted to encourage trucks to transport as much fruit lo market as possible.

Florida Citrus Mutual sprayed trees with sprinklers for citrus growers.

Scientists can't yet make an invisibility cloak1 like the ……try to invent a device similar in idea to the invisible cloak he uses.

Their wavelengths are longer than those of visible light. Microwaves bounce off it when they strike it.

disk or plate placed under a drinking glass to protect a table top. die cloaking device works only for microwaves.

A concept car developed by Japanese company ……

It has sensors locked up in the ignition system.

breathalyzer attached to a car's seat belt,

It monitors the driver's eyes to see if he needs a rest.

Nissan aims to improve the detection technology to reduce the fatality rate.

The car will automatically keep to its lane.

Learning how to fly took nature millions of years…….

The two professors of CUT programmed the data on how the robot flapped its wings.

It twitched but gradually gained height.

The winged robot could never really fly.

A movement detector.

All the above.

In what resembles a journey to the center……

erupted in 1991.

predicting volcano eruptions.

Because Japan has many living volcano

about half way up the mountain.

drill a hole into the core of a volcano.

Even with the best will1 in the world, reducing….

despite the difficulty, scientists have some options to prevent global warming.

think the problem has been solved.

Methadone is an effective way to treat a hard heroin addict.

To apply sunscreen to the Earth.

It decreases greenhouse gases in the atmosphere.

Worldwide every day, we devour the energy equivalent ……Oil supply is decreasing.

Coal is the most environmentally unfriendly fuel next to oil. The United States.

There will soon be an energy crisis.

The sea level will go up.

Prolonging human life has increased the size of the…….

a decrease in death rates.

infants could be left dead in times of starvation.

Many of them have a very hard life.

the need to take care of a sick and weak person.

Critical.

Oceans cover more than two-thirds of our planet….

A submersible.

It can carry explorers as deep as 6,500 meters.

the ocean. Shape.

Both A and B.

Scientists have been studying natural sources of ……..

It was produced in oxygen-free environments.

an environment with the same concentration of oxygen as the Earth has.

The higher the temperature, the greater the amount of methane emissions.

Microbes in plants produce methane.

Less methane reaches the atmosphere.

You've probably heard that no two snowflakes are……

No two snowflakes are exactly the same in shape.

They are six-sided.

Humidity and temperature.

admires the beauty of the snowflakes.

create snowflakes that are exactly alike.

The graceful wooden windmills that have broken up ……Wooden shoes and wooden windmills.

It is a high-tech machine designed to generate energy for urban people.

can be carried up to the rooftop without a crane.

the Netherlands is a small country with a large population. Both A and C.

Coal burning deep underground in China, India and ……poisonous elements released by the underground fires can pollute water sources.

Coal heats up on its own and catches fire and burns.

Coal fires can have an impact on the environment.

He has detected and monitored underground fires in the Netherlands. ',

Cutting off the oxygen supply.

A meager diet may give you health and long life, …….

We have to begin dieting since childhood.

To illustrate the effect of meager food on mice.

They are more likely to suffer from inflammation.

The mice that started dieting in old age.

dieting is not a good method to give us health and long life. Male pilots flying general aviation (private) aircraft in….. Gender difference in relation to types of aircraft crashes.

Only mature pilots are studied to determine the gender differences in the reasons for aircraft crash,

They studied the findings of several previous research projects. Loss of control on landing or takeoff and stalling.

male pilots are found to make more errors in decision-making. Joe Coyne slides into the driver's seat, starts up the car ……Coyne is not really driving so it is impossible for him to have hit the woman.

All of the above.

In challenging driving situations, drivers do not have any additional mental energy to deal with something else.

want to determine the best ways of giving navigational information system.

Men prefer more general directions and women prefer route directions.

To sleep. Perchance to file"? Findings published …….. Docs brain arrange memories in useful order during sleep? Somatosensory neocortex and hippocampus work together in memory consolidation.

The poorer the memory, the poorer glucose tolerance.

The more hippocampus shrinks, the poorer one's memory.

To control glucose levels.

Experiments under way in several labs aim to create …….. GM foods may bring about great benefits to humans.

It is cited to show GM foods also have a dark side.

They may have a higher ability to adapt to the environment. The United States has not banned GM foods.

We cannot tell from the passage.

In the digital realm, the next big advance will …….

are in its initial stage of development.

machines can be our agents as they understand our thoughts.

It motivates the development of the digital world.

All of the above.

In a personalized market, products are tailored toeachconsumer.

A hurricane is a fiercely powerful, rotating form of tropical ……

A calm central region of low pressure between 12 to 60 miles in diameter.

The tropical waters are warm and calm.

To supply the motive force or power and cause to function. Low pressure

The humanitarian crisis is as serious as that of the great depression.

A team of researchers in California has developed a ……Neurons in the brain.

f MRI helps scientists to discover how the brain develops intelligently.

"marking the parts of the brain that arc processing information" Two volunteers.

Your Thoughts Can Be Scanned.

The withdrawal of Nevada's…

Canceling.

should be approved by local people and states.

The decision by Congress was accepted by local communities. Efforts should be made to develop nuclear disposal sites to suit the circumstances of the region.

Waste disposal sites are located close to reactors and in places suitable for the regional circumstances.

Using die power of the sun is nothing new. ……

Plants have been using solar energy for billions of years.. Because they want green plants lo become a new source of energy.

When there is no oxygen in the air.

It is too slow for algae to produce hydrogen when the sulfate is removed.

They are cheap to eat.

6. Why do some scientists study how plants convert sunlight carbon dioxide and water into sugars and starches?

Because they want green plants to become a new source of energy.

A device that provides early warning of a landslide ……Landslides.

All of the above.

Because the common methods can cause false alarms.

It is filled in with gravel.

Evidences.

In what may be bad news for bars and pubs, ……. who drink alcohol outside of meals.

It increases by 20 percent the possibility of cancer in all sites.

3 drinks.

Laryngeal cancer.

reduces the risk of laryngeal cancer.

Factory fanning could soon enter a new era of mass ….. Cloned chickens are bulk-produced with the same growth rate, weight and taste.

The US's National Institute of Science and Technology. chickens could grow to the same weight but with less feed. Origen has joined hands with Embrex in producing cell-injecting machines.

farmers can order certain strains of chicken only.

Scientists watched closely last spring as a haze of …..

of desert dust and hydrocarbons.

heir ability to reflect light is much stronger.

She collected samples of pollutants on the Northwest coast for further tests.

The two research teams whose Findings Price correlates hers with are based in Asia.

Pollutants coming from Europe are not the main source of pollution in North America.

Oil and gas will run out too fast for doomsday……..

Oil and gas will run out so fast that Earth's doomsday will never materialize.

cut C02 emissions.

3，500 billion by a growing number of scientists.

He thinks that IPCC's estimates are more optimistic than the Swedes.

A switch to burning coal would produce disastrous environmental problems.

Today petroleum provides around 40% of the world's …..

A and B.

is the largest of all the hydroelectric dams in the world. Norway.

All of the above.

are renewable so sustainable.

There are several different methods that can be used …….. Imagination of the forecaster.

if weather conditions do not change much.

the weather features need to be constant for a long period of lime.

Both climatology method and analog method.

when the current weather scenario differs from the analog. Judith S. Weis, a biology professor who serves as ……. School boards oppose AIBS's effort to defend the theory of evolution.

Darwin's theory is denied as the central theory of biology. more than 80 societies and 250,000 members.

is fundamental to the development of modern genetics, molecular biology and genomics.

Because the term creationism is too direct.

Invisibility cloaks' would have remained ……

They are nonexistent in nature.

as it can help scientists to see even the wavelengths of visible light.

an acoustic cloak that can shuffle waves of sound.

it is possible to build an acoustic cloak in theory but far from

reality.

Surround them with metamaterials as protective shields.

A male zebra finch1 chirps away to himself. Suddently……Male zebra finches change their songs in female zebra finches' presence.

Female finches liked songs male finches sang for them.

Songs sung by male finches for female finches.

Male zebra finches sing to themselves.

Birdsongs as communication.

Cryptic species — animals that appear identical but are ….. The results of the research can help our understanding of "survival of the fittest. "

Both B and C.

Not yet.

They are two genetically distant species.

identified only one mosquito species instead of six species. NASA scientists said that Mars was covered once by ……. Water in a soil sample.

The samples got stuck inside the scoop.

Scientists have been trying to break the ice-rich layers of soil on Mars.

They are from both America and Canada.

It imitates human vision and is able to capture three-dimensional images.

Cell phones are a danger on the road in more ways ….. both A and C.

Before the number of cell phone users reached a critical mass The number of traffic deaths was reduced in the late 1980s and part of the 1990s due to cell phone use.

It had a life-taking effect because there weren't enough cell phones in use then .

The number of cell phone users reached about 100 million. 2012理工完形填空

第三篇Germs on Banknotes

People in different countries use different types of money : yuan in China, pesos in Mexico, pounds in the United Kingdom, dollars in the United States, Australia and New Zealand. They may use different currencies, but these countries, and probably all countries, still have one thing in common: Germs on the banknotes.

Scientists have been studying the germs on money for well over100 years. At the turn of the 20th century, some researchers began to suspect that germs living on money could spread disease.

Most studies of germy money have looked at the germs on the currency within one country. In a new study, Frank Vriesekoop and other researchers compared the germ populations found on bills of different countries

Vriesekoop is a microbiologist at the University of Ballarat in Australia. He led the study, which compared the germ populations found on money gathered from 10 nations. The scientists studied 1,280 banknotes in total; all came from places where people buy food, like supermarkets street vendors and cafes, because those businesses often rely on cash.

Overall, the Australian dollars hosted the fewest live bacteria----no more than 10 per square centimeter. Chinese yuan had the most ---- about 100 per square centimeter. Most of the germs on money probably would not cause harm.

What we call “paper” money usually isn't made from paper. The U. S. dollar, for example, is printed on fabric that is mostly cotton .Different countries may use different materials to print their money. Some of the currencies studied by Vriesekoop and his team such as the American dollar were made from cotton. Others were made from polymers.

The three currencies with the lowest numbers of bacteria were all printed on polymers. They included the Australian dollar, the New Zealand dollar and some Mexican pesos.

The other currencies were printed on fabric made mostly of cotton. Fewer germs lived on the polymer notes. This connection suggests that germs have a harder time staying alive on polymer surfaces. Scientists need to do more studies to understand how germs live on money-----and whether or not we need to be concerned. Vnesekoop is now starting a study that will compare the amounts of time bacteria can stay alive on different types of bills.

Whatever Vriesekoop finds, the fact remains: Paper money harbors germs We should wash our hands after touching it; after all, you never know where your money’s been. Or what's living on it

第十篇 Chicken Soup for the Soul：Comfort Food Fights Loneliness

Mashed potatoes, macaroni and cheese, may be bad for your arteries， but according to a study in Psychological Science, they’re good for your heart and emotions．The study focuses on “comfort food” and how it makes people feel．

"For me personally, food has always played a big role in my family,” says Jordan Troisi, a graduate student at the University of Buffalo, and lead author on the study．The study came out of the research program of his co—author Shira Gabriel．It has looked at non-human things that may affect human emotions．Some people reduce loneliness by bonding with their favorite TV show, building virtual relationships with a pop song singer or looking at pictures of loved ones．Troisi and Gabriel wondered if comfort food could have the same effect by making people think of their nearest and dearest.

In one experiment, in order to make participants feel lonely, the researchers had them write for six minutes about a fight with someone close to them. Others were given an emotionally neutral writing assignment. Then , some people in each group wrote about the experience of eating a comfort food and others wrote about eating a new food．Finally, the researchers had participants complete questions about their levels of loneliness．Writing about a fight with a close person made people feel lonely．But people who were generally secure in their relationships would feel less lonely by writing about a comfort food．"We have found that comfort foods are consistently associated with those close to us." says Troisi．"Thinking about or consuming these foods later then serves as a reminder of those close others." In their essays on comfort food, many people wrote about the experience of eating food with family and friends.

In another experiment, eating chicken soup in the lab made people think more about relationships, but only if they considered chicken soup to be a comfort food. This was a question they had been asked long before the experiment, along with many other questions, so they wouldn’t remember it.

Throughout everyone’s daily lives they experience stress, often associated with our connections with others," Troisi says．"Comfort food Can be an easy remedy for loneliness．

*第十一篇 Climate Change Poses Major Risks for Unprepared Cities

A new examination of urban policies has been carried out recently by Patricia Romero Lankao．She is a sociologist specializing in climate change and urban development．She warns that many of the world’s fast-growing urban areas，especially in developing countries, will likely suffer from the impacts of changing climate．Her work also concludes that most cities are failing to reduce emissions of carbon dioxide and other greenhouse gases. These gases are known to affect the atmosphere．”Climate change is a deeply local issue and poses profound threats to the growing cities of the world,”says Romero Lankao. ”But too few cities are developing effective strategies to protect their residents."

Cities are major sources of greenhouse gases．And urban populations are likely to be among those most severely affected by future climate change. Lankao’s findings highlight ways in which city-residents are particularly vulnerable, and suggest policy interventions that could offer immediate and longer-term benefits．

The locations and dense construction patterns of cities often place their populations at greater risk for natural disasters. Potential threats associated with climate include storm surges and prolonged hot weather. Storm surges can flood coastal areas and prolonged hot weather can heat heavily paved cities more than surrounding areas．The impacts of such natural events can be more serious in an urban environment．For example，a prolonged heat wave can increase existing levels of air pollution，causing widespread health problems．Poorer neighborhoods that may lack basic facilities such as drinking water or a dependable network of roads，are especially vulnerable to natural disasters．Many residents in poorer countries live in substandard housing without access to reliable drinking water，roads and basic services.

Local governments, therefore, should take measures to protect their residents.”Unfortunately，they tend to move towards rhetoric rather than meaningful responses, Romero Lankao writes, ” They don’t impose construction standards that could reduce heating and air conditioning needs. They don't emphasize mass transit and reduce automobile use. In fact, many local governments are taking a hands-off approach.”Thus, she urges them to change their idle policies and to take strong steps to prevent the harmful effects of climate change on cities.

*第十二篇 Free Statins With Fast Food Could Neutralize Heart Risk

Fast food outlets could provide statin drugs free of charge so that customers can reduce the heart disease dangers of fatty food, researchers at Imperial College London suggest in a new study．

Statins reduce the amount of unhealthy ”LDL” cholesterol in the blood. A wealth of trial data has proven them to be highly effective at lowering a person’s heart attack risk .

In a paper published in the American Journal of Cardiology，Dr Darrel Francis and colleagues calculate that the reduction in heart attack risk offered by a statin is enough to offset the increase in heart attack risk from eating a cheeseburger and drinking a milkshake．

Dr Francis，from the National Heart and Lung Institute at Imperial College London，who is the senior author of the study, said:”Statins don’t cut out a11 of the unhealthy effects of cheeseburgers and French fries．It’s better to avoid fatty food altogether．But we’ve worked out that in terms of your possibility of having a heart attack. Taking a statin can reduce your risk to more or less the same degree as a fast food meal increases it.”

“It’s ironic that people are free to take as many unhealthv condiments in fast food outlets as they like , but statins, which are beneficial to heart health, have to be prescribed. It makes sense to make risk-reducing statins available just as easily as the unhealthy condiments that are provided free of charge．It would cost less than 5 pence per customer一not much different to a sachet of sugar.” Dr Francis said．

When people engage in risky behaviours like driving or smoking, they’re encouraged to take measures that lower their risk, 1ike wearing a seatbelt or choosing cigarettes with filters. Taking a statin is a rational way of lowering some of the risks of eating a fatty meal．

+第十三篇Solar Power without Solar Cells

A dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.

The researchers found a way to make an "optical battery," said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.

Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength equivalent to a strong electric effect.

"This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation," Rand said. "In solar cells, the light goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source." What makes this possible is a previously undetected brand of "optical rectification," says William Fisher, a doctoral student in applied physics. In traditional optical rectification, light's electric field causes a charge separation, or a pulling apart of the positive and negative charges in a material. This sets up a voltage, similar to that in a battery.

Rand and Fisher found that under the right circumstances and in right types of materials, the light's magnetic field can also create optical rectification. The light must be shone through

a material that does not conduct electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this intense on its own, but new materials are being sought that would work at lower intensities, Fisher said.

"In our most recent paper, we show that incoherent light like sunlight is theoretically almost as. effective in producing charge separation as laser light is," Fisher said.

This new technique could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. That's equivalent to today's commercial-grade solar cells.

"To manufacture modern solar cells, you have to do extensive semiconductor processing," Fisher said. "All we would need are lenses to focus the light and a fiber to guide it. Glass works for both . It's already made in bulk, and it doesn't require as much processing. Transparent ceramics might be even better."

+第十五篇“Liquefaction”Key to Much of Japanese Earthquake Damage

The massive subduction zone earthquake in Japan caused a significant level of soil"liquefaction" that has surprised researchers with its widespread severity, a new analysis shows.

"We've seen localized examples of soil liquefaction as extreme as this before, but the distance and extent of damage in Japan were unusually severe," said Scott Ashford, a professor of geotechnical engineering at Oregon State University. "Entire structures were tilted and sinking into the sediments," Ashford said. "The shifts in soil destroyed water, drain and gas pipelines, crippling the utilities and infrastructure these communities need to function. We saw some places that sank as much as four feet."

Some degree of soil liquefaction is common in almost any major earthquake. It's a phenomenon in which soils soaked with water, particularly recent sediments or sand, can lose much of their strength and flow during an earthquake. This can allow structures to shift or sink or collapse.

But most earthquakes are much shorter than the recent event in Japan, Ashford said. The length of the Japanese earthquake, as much as five minutes, may force researchers to reconsider the extent of liquefaction damage possibly occurring in situations such as this.

"With such a long-lasting earthquake, we saw how structures that might have been okay after 30 seconds just continued to sink and tilt as the shaking continued for several more minutes," he said. "And it was clear that younger sediments, and especially areas built on recently filled ground, are much more vulnerable."

The data provided by analyzing the Japanese earthquake, researchers said, should make it possible to improve the understanding of this soil phenomenon and better prepare for it in the future. Ashford said it was critical for the team to collect the information quickly, before damage was removed in the recovery efforts.

"There's no doubt that we'll learn things from what happened in Japan that will help us to reduce risks in other similar events," Ashford said. "Future construction in some places may make more use of techniques known to reduce liquefaction, such as better compaction to make soils dense, or use of reinforcing stone columns."

Ashford pointed out that northern California have younger soils vulnerable to liquefaction ---on the coast, near river deposits or in areas with filled ground. The "young" sediments, in geologic terms, may be those deposited within the past 10,000 years or more. In Oregon, for instance, that describes much of downtown Portland, the Portland International Airport and other cities.

Anything near a river and old flood plains is a suspect, and the Oregon Department of Transportation has already concluded that 1,100 bridges in the state are at risk from an earthquake. Fewer than 15 percent of them have been reinforced to prevent collapse. Japan has suffered tremendous losses in the March 11 earthquake, but Japanese construction standards helped prevent many buildings from collapse ---even as they tilted and sank into the ground.

Captain Cook Arrow Legend（C）

It was a great legend while it lasted, but DNA testing has finally ended a two-century-old story of the Hawiian arrow carved from the bone of British explorer Captain James Cook who died in the Sandwich Islands in 1779.

“There is no Cook in the Australian Museum,”museum collection manager Jude Philip said not long ago in announcing the DNA evidence that the arrow was not made of Cook’s bone. But that will not stop the museum from continuing to display the arrow in its exhibition, “Uncovered: Treasures of the Australian Museum3,”which does include a feather cape presented to Cook by Hawaiian King Kalani’opu’u in 1778. Cook was one of Britain’s great explorers and is credited with discovering the “Great South Land,”now Australia, in 1770. He was clubbed to death in the Sandwich Islands, now Hawaii. The legend of Cook’s arrow began in 1824when Hawaiian King Kamehameha on his deathbed gave the arrow to William Adams, a London surgeon and relative of Cook’s wife, saying it was made of Cook’s bone after the fatal fight with islanders.

In the 1890s the arrow was given to the Australian Museum and the legend continued until it came face-to-face with science. DNA testing by laboratories in Australia and New Zealand revealed the arrow was not made of Cook’s bone but was more likely made of animal bone, said Philp.

However, Cook’s fans refuse to give up hope that one Cook legend will prove true and that part of his remains will still be uncovered, as they say there is evidence not all of Cook’s body was buried at sea in 1779. “On this occasion technology has won,”said Cliff Thornton, president of the Captain Cook Society, in a statement from Britain. “But I am sure that one of these days…one of the Cook legends will prove to be true and it will happen one day.”

Avalanche and Its Safety(C)

An avalanche is a sudden and rapid flow of snow, often mixed with air and water, down a mountainside. Avalanches are among the biggest dangers in the mountains for both life and property.

All avalanches are caused by an over-burden of material, typically snowpack, that is too massive and unstable for the

slope that supports it. Determining the critical load, the amount of over-burden which is likely to cause an avalanche, is a complex task involving the evaluation of a number of factors. Terrain slopes flatter than 25 degrees or steeper than 60 degrees typically have a low risk of avalanche. Snow does not gather significantly on steep slopes; also, snow does not flow easily on flat slopes. Human-triggered avalanches have the greatest incidence when the snow’s angle of rest is between 35 and 45 degrees; the critical angle, the angle at which the human incidence of avalanches is greatest, is 38 degree. The rule of thumb is : A slope that is flat enough to hold snow but steep enough to ski has the potential to generate an avalanche, regardless of the angle. Additionally, avalanche risk increases with use ; that is, the more a slope is disturbed by skiers, the more likely it is that an avalanche will occur.

Due to the complexity of the subject, winter traveling in the backcountry is never 100% safe. Good avalanche safety is a continuous process, including route selection and examination of the snowpack, weather conditions, and human factors. Several well-known good habits can also reduce the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings should be paid attention to. Never follow in the tracks of others without your own evaluations; snow conditions are almost certain to have changed since they were made. Observe the terrain and note obvious avalanche paths where plants are missing or damaged. Avoid traveling below others who might trigger an avalanche.

Animal’s “Sixth Sense”（C）

A tsunami was triggered by an earthquake in the Indian Ocean in December, 2004. It killed tens of thousands of people in Asia and East Africa. Wild animals, howeve r , seem to have escaped that terrible tsunami. This phenomenon adds weight to notions that I they possess a “sixth sense”for disasters, experts said.

Sri Lankan wildlife officials have said the giant waves that killed over 24,000 people along the Indian Ocean island’s coast clearly missed wild beasts, with no dead animals found.

“No elephants are dead, not even a dead rabbit. I think animals can sense disaster. They have a sixth sense. They know when things are happening.”H.D. Ratnayake, deputy director of Sri Lanka’s Wildlife Department, said about one month after the tsunami attack. The waves washed floodwaters up to 2 miles inland at Yala National Park in the ravaged southeast, Sri Lanka’s biggest wildlife reserve and home to hundreds of wild elephants and several leopards.

“There has been a lot of apparent evidence about dogs barking or birds migrating before volcanic eruptions or earthquakes. But it has not been proven,”said Matthew van Lierop an animal behavior specialis t at Johannesburg Zoo. “There have been no specific studies because you can’t really test it in a lab or field setting2,”he told Reuters. Other authorities concurred with this assessment .

“Wildlife seem to be able to pick up certain phenomenon, especially birds…there are many reports of birds detecting impending disasters,”said Clive Walker, who has written several books on African wildlife.

Animals certainly rely on the known senses such as smell or hearing to avoid danger such as predators.

The notion of an animal “sixth sense”-or some other mythical power-is an enduring one3 which the evidence on Sri Lanka’s ravaged coast is likely to add to.

The Romans saw owls as omens of impending disaster and many ancient cultures viewed elephants as sacred animals endowed with special powers or attributes.

Singing Alarms Could Save the Blind（C）

If you cannot see, you may not be able to find your way out of a burning building—and that could be fatal. A company in Leeds could change all that with directional sound alarms capable of guiding you to the exit.

Sound Alert, a company run by the University of Leeds, is installing the alarms in a residential home for blind people in Sommerset and a resource center for the blind in Cumbria. The alarms produce a wide range of frequencies that enable the brain to determine where the sound is coming from.

Deborah Withington of Sound Alert says that the alarms use most of the frequencies that can be heard by humans. “It is a burst of white noise that people say sounds like static on the radio,” she says. “Its life-saving potential is great.”

She conducted an experiment in which people were filmed by thermal-imaging cameras trying to find their way out of a large smoke-filled room. It took them nearly four minutes to find the door without a sound alarm, but only 15 seconds with one.

Withington studies how the brain processes sounds at the university. She says that the source of a wide band of frequencies can be pinpointed more easily than the source of a narrow band. Alarms based on the same concept have already been installed on emergency vehicles.

The alarms will also include rising or falling frequencies to indicate whether people should go up or down stairs. They were developed with the aid of a large grant from British Nuclear Fuels.

Car Thieves Could Be Stopped Remotely（C）

Speeding off in a stolen car, the thief thinks he has got a great catch. But he is in a nasty surprise. The car is fitted with a remote immobilizer, and a radio signal from a control center miles away will ensure that once the thief switches the engine off , he will not be able to start it again.

For now, such devices are only available for fleets of trucks and specialist vehicles used on construction sites. But remote immobilization technology could soon start to trickle down to ordinary cars, and should be available to ordinary cars in the UK in two months.

The idea goes like this. A control box fitted to the car incorporates a miniature cellphone, a microprocessor and memory, and a GPS satellite positioning receiver. If the car is stolen, a coded cellphone signal will tell the unit to block the vehicle’s engine management system and prevent the engine being restarted.

There are even plans for immobilizers that shut down vehicles on the move, though there are fears over the safety implications of such a system.

In the UK, an array of technical fixes is already making life harder for car thieves. “The pattern of vehicles crime has changed,” says Martyn Randall of Thatcham, a security research organization based in Berkshire that is funded in part by the

motor insurance industry.

He says it would only take him a few minutes to teach a novice how to steal a car using a bare minimum of tools. But only if the car is more than 10 years old.

Modern cars are a far tougher proposition：as their engine management computer will not allow them to start unless they receive a unique ID code beamed out by the ignition key. In the UK, technologies like this have helped achieve a 31 per cent drop in vehicle-related crime since 1997.

But determined criminals are still managing to find other ways to steal cars. Often by getting hold of the owner’s keys in a burglary. In 2000, 12 per cent of vehicles stolen in the UK were taken using the owner’s keys double the previous year’s figure. Remote-controlled immobilization system would put a major new obstacle in the criminal’s way by making such thefts pointless. A group that includes Thatcham, the police, insurance companies and security technology firms have developed standards for a system that could go on the market sooner than the customer expects.

An Intelligent Car（C）

Driving needs sharp eyes, keen ears, quick brain, and coordination between hands and the brain. Many human drivers have all these and can control a fast-moving car. But how does an intelligent car control itself?

There is a virtual drive in the smart car. This virtual driver has “eyes,”“brains,”“hands” and “feet,” too. The minicameras on each side of the car are his “eyes,” which observe the road conditions ahead of it. They watch the traffic to the car’s left and right. There is also a highly automatic driving system in the car. It is the built-in computer, which is the virtual driver’s “brain.” His “brain” calculates the speeds of other moving cars near it and analyzes their positions. Basing on this information, it chooses the right path for the intelligent car, and gives instructions to the “hands” and “feet” to act accordingly. In this way, the virtual driver controls his car.

What is the virtual driver’s best advantage? He reacts quickly. The minicameras are sending images continuously to the “brain.”It completes the processing of the images within 100 milliseconds. However, the world’s best driver at least needs one second to react. Besides, when he takes action, he needs one more second.

The virtual driver is really wonderful. He can reduce the accident rate considerably on expressways. In this case, can we let him have the wheel at any time and in any place? Experts warn what we cannot do that just yet. His ability to recognize things is still limited . He can now only drive an intelligent car on expressways.

A Biological Clock（C）

Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells plants when to form flowers and when the flowers should open. It tells insects when to leave the protective cocoon and fly away, and it tells animals and human beings when to eat, sleep and wake. Events outside the plant and animal affect the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the number of hours of daylight. In the short days of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight summer.

Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration flight twice each year. Birds prevented from flying become restless when it is time for the trip, but they become calm again when the time of the flight has ended.

Scientists say they are beginning to learn which parts of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain seems to control the timing of some of our actions. These cells tell a person when to awaken , when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities.

Dr. Moorhead is studying how our biological clocks affect the way we do our work. For example, most of us have great difficulty if we must often change to different work hours.

It can take many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said such understanding could cut sickness and accidents at work and would help increase a factory’s production.

Wonder Webs（C）

Spider webs are more than homes, and they are ingenious traps. And the world’s best web spinner may be the Goldern Orb Weaver spider. The female Orb Weaver spins a web of fibers thin enough to be invisible to insect prêt, yet tough enough to snare a flying bird without breaking.

The secret of the web’s strength? A type of super-resilient silk called dragline. When the female spider is ready to weave the web’s spokes and frame, she uses her legs to draw the airy thread out through a hollow nozzle in her belly. Dragline is not sticky, so the spider can race back and forth along it to spin the web’s trademark spiral.

Unlike some spiders that weave a new web every day, a Golden Orb Weaver reuses her handiwork until it falls apart, sometimes not for two years. The silky thread is five times stronger than steel by weight and absorbs the force of an impact three times better than Kevlar, a high-strength human-made material used in bullet-proof vests. And thanks to its high tensile strength, or the ability to resist breaking under the pulling force called tension, a single strand can stretch up to 40 percent longer than its original length and snap back as well as new. No human-made fiber even comes close .

It is no wonder manufacturers are clamoring for spider silk. In the consumer pipeline: high-performance fabrics for athletes and stockings that never run2. Think parachute cords and suspension bridge cables. A steady supply of spider silk would be worth billions of dollars—but how to produce it? Harvesting silk on spider farms does not work because the territorial arthropods have a tendency to devour their neighbors.

Now, scientists at the biotechnology company Nexia are spinning artificial silk modeled after Goldern Orb dragline. The first step: extract silk-making genes from the spiders. Next, implant the genes into goat egg cells. The nanny goats that grow from the eggs secrete dragline silk proteins in their milk . “The young goats pass on the silk-making gene without any help

from us,”says Nexia president Jeffrey Turner. Nexia is still perfecting the spinning process, but they hope artificial spider silk will soon be snagging customers as fast as the real thing snags bugs.

Less Is More（C）

It sounds all wrong—drilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and lighter packaging materials. Carpenters have known for centuries that some woods are tougher than others. Hickory, for example, was turned into axe handles and cartwheel spokes because it can absorb shocks without breaking. White oak, for example, is much more easily damaged,although it is almost as dense. Julian Vincent at Bathe University and his team were convinced the wood’s internal structure could explain the differences.

Many trees have tubular vessels that run up the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers thought this layout might distribute a blow’s energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimetres across into a block of spruce, a wood with no vessels, and found that it withstood a harder knock. Only when there more than about 30 holes per square centimeter did the wood’s performance drop off.

A uniform substance doesn’t cope well with knocks because only a small proportion of the material is actually affected. All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left behind are pristine. But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break, says Vincent. “You are controlling the places where the wood breaks, and it can then absorb more energy , more safely.”

The researchers believe the principle could be applied to any material—for example, to manufacture lighter and more protective packaging. It could also be used in car bumpers, crash barriers and armour for military vehicles, says Ulrike Wegst,at the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you’d need to design the substance with the direction of force in mind. “The direction of loading is crucial,” she says.

China to Help Europe Develop GPS Rival（B）

China is to contribute to a new global satellite navigation system being developed by European nations. The Galileo satellite system will offer a more accurate civilian alternative to the Global Positioning System (GPS), operated by the US military. China will provide 230m Euros (USD 259m) in funding and will cooperate with technical, manufacturing and market development. “China will help Galileo to become the major world infrastructure for the growing market for location services,” said Loyola de Palacio, EU transport commissioner.

A new center that will coordinate co-operation was also announced by the European Commission, the European Space Agency (ESA) and the Chinese Ministry of Science and Technology not long ago. The China-Europe Global Navigation Satellite System Technical Training and Cooperation Center will be located at Beijing University. China has a substantial satellite launch industry and could potentially help launch the Galileo satellites.

The US has claimed that Galileo could interfere with the US ability to downgrade the GPS service during military conflicts. European officials say this is unfounded and counter that US opposition is due to the commercial challenge Galileo would present to GPS. Galileo will be precise to within a meter, while the civilian GPS service is accurate to around 10 meters.

The Galileo satellite constellation will consist of 27 operational and three reserve satellites orbiting the Earth at an altitude of 23,600 km. The satellites will be strung along three medium-Earth orbits at 56 degrees inclination to the equator and will provide global coverage. The system should be operational by 2008 and the entire project is expected to cost around 3.2 billion Euros (USD 3.6 billion).

The European Commission has said Galileo will primarily be used for transportation technology, scientific research, land management and disaster monitoring.

Galileo will provide two signals; a standard civilian one and an encrypted, wide-band signal called the Public Regulated Service (PRS). This second signal is designed to withstand localized jamming and will be used by police and military services in Europe. European Commission officials have said China will not be given access to the PRS.

The first Galileo satellite is scheduled to launch late in 2004. Clocks on board the the satellite will be synchronized through 20 ground sensors stations, two command centers and 15 uplink stations.

Receivers on the ground will use time signals from the satellites to precisely calculate their location. A “search and rescue” function will also let distress signals be relayed through the constellation of satellites.

Cell Phone Lets Your Secret Out(A)

Your cell phone holds secrets about you. Besides the names and numbers that you’ve programmed into it, traces of your DNA linger on the device, according to a new study.

DNA is genetic material that appears in every cell. Like your fingerprint, your DNA is unique to you —unless you have an identical twin. Scientists today routinely analyze DNA in blood, saliva, or hair left behind at the scene of a crime. The results often help detectives identify criminals and their victims. Your cell phone can reveal more about you than you might think. Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the device. This made her wonder whether traces of DNA lingered on cell phones—even when no blood was involved. So she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones of 10 volunteers. They used swabs to collect invisible traces of the users from two parts of the phone: the outside, where the user holds it, and the speaker , which is placed at the user’s ear.

The scientists scrubbed the phones using a solution made mostly of alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones back for another week. Then the researchers collected the phones and

repeated the swabbing of each phone once more.

The scientists discovered DNA that belonged to the phone’s speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. Surprisingly, DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won’t remove all traces of evidence from a criminal’s device. So cell phones can now be added to the list of clues that can clinch a crime-scene investigation.

Sharks Perform a Service for Earth’s Waters (A)

It is hard to get people to think of sharks as anything but enemy. They are thought to attack people frequently. But these fish perform a valuable service for earth’s waters and for human beings. Yet business and sport fishing are threatening their existence. Some sharks are at risk of disappearing from Earth.

Warm weather may influence both fish and shark activity. Many fish swim near coastal areas because of their warm waters. Experts say sharks may follow the fish into the same areas, where people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person for a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the times when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack.

A shark has an extremely good sense of smell. It can find small amounts of substances in water, such as blood, body liquids and chemicals produced by animals. These powerful senses help sharks find their food. Sharks eat fish, any other sharks, and plants that live in the ocean.

Medical researchers want to learn more about the shark’s body defense and immune systems against disease. Researchers know that sharks recover quickly from injuries. They study the shark in hopes of finding a way to fight human disease. Sharks are important for the world’s oceans. They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too great . This protects the plants and other forms of life that exist in the oceans.