Antidepressant（抗忧郁）drugs such as Prozac were viewed in the early 1900's as wonder pills that would remove depressive blues for good. But in the past five years, growing scientific evidence has shown these drugs work for only a minority of people. And now a research journal says that these antidepressants can make many patients' depression worse. This alarming suggestion centres on the very chemical that is targeted by antidepressants-serotonin（血清素）. Drugs such as Prozac are known as selective serotonin re-uptake inhibitors（or SSRIs）. Their aim is to increase the level of this  “feel-good” chemical in the brain.

But the new research, published in the journal Frontiers In Evolutionary Psychology, points out that serotonin is like a chemical Swiss Army knife, performing a very wide range of jobs in the brain and body. And when we start changing serotonin levels purposely, it may cause a wide range of unwanted effects. These can include digestive problems and even early deaths in older people, according to the study's lead researcher Paul Andrews. “ We need to be much more cautious about use of these drugs,” says Andrews, an assistant professor of evolutionary psychology at McMaster University in Ontario, Canada.

Previous research has suggested that the drugs provide little benefit for most people with mild depression, and actively help only a few of the most severely depressed. Famous psychologist Irving Kirsch has found that for many patients, SSRIs are no more effective than a placebo pill. A research in 2010 on Danish children found a small, but significant, increase in the risk of heart problems among babies whose mothers had used SSRIs in early pregnancy. The key to understanding these side-effects is serotonin, says Andrews. Serotonin is also the reason why patients can often end up feeling still more depressed after they have finished a course of SSRI drugs. He argues that SSRI antidepressants disturb the brain, leaving the patient an even greater depression than before.

“After long use, when a patient stops taking SSRIs, the brain will lower its levels of serotonin production,” he says, adding that it also changes the way receptors in the brain respond to serotonin, making the brain less sensitive to the chemical. These changes are believed to be temporary, but studies indicate that the effects may continue for up to two years.

Most disturbingly of all, Andrews' review features three recent studies which, he says , show that elderly antidepressant users are more likely to die earlier than non-users, even after taking other important variables into account. One study, published in the British Medical Journal last year, found patients given SSRIs were more than 4 per cent more likely to die in the next year than those not on the drugs.

“Serotonin is an ancient chemical,” says Andrews. “It is regulating many different processes, and when you disturb these things, you can expect that it is going to cause some harm.”

Stafford Lightman, professor of medicine at the University of Bristol, and a leading UK expert in brain chemicals and hormones, says Andrews’ review highlights some important problems, yet it should also be taken with a pinch of salt. “This report is doing the opposite of what drug companies do,” he says. “Drug companies selectively present all the positives in their research, while this search selectively presents all the negatives that can be found. Nevertheless, Andrews' study is useful in that it is always worth pointing out that there is a downside to any medicine. ” Professor Lightman adds that there is still a great deal we don't know about SSRIs-not least what they actually do in our brains.

When it comes to understanding why the drugs work only for a limited part of patients, U.S.  scientists think they might now have the answer. They think that in many depressed patients, it’s not only the lack of feel-good serotonin causing their depression, but also a failure in the area of the brain that produces new cells throughout our lives. This area, the hippocampus, is also responsible for regulating mood and memory. Research suggests that in patients whose hippocampus has lost the ability to produce new cells, SSRIs do not bring any benefit.

1.According to paragraph 2, serotonin, like a chemical Swiss Army knife, can             .

A. make many patients' depression worse

B. cause a wide range of unwanted effects

C. affect human body and brain in various ways

D. provide little benefit for most depressed people

2.In Stafford Lightman's opinion,                     .

A. drug companies don't know the negative effect of antidepressants

B. Andrews focused on different things from the drug companies

C. scientists have found what SSRIs do in the brain

D. Andrews' research has no medical value

3.Which of the following is TRUE about SSRIs?

A. They are used to increase the “feel-good” medical in the brain.

B. They can work even when the hippocampus can't produce new cells.

C. They create a risk of heart problems in pregnant women.

D. They are responsible for controlling mood and memory.

4.What is the text mainly about?

A. The aim of drug companies

B. The function of SSRIs

C. The side-effects of antidepressants

D. The cause of depression

 

We might like to think we're not influenced by other people, but a new study into the group-buying mechanisms（机制） - like those used on coupon（优惠券） sites such as Groupon and LivingSocial - reveals that telling buyers who come later to the offer how many have already signed up increases the number of purchasers.

Researchers at the University of Toronto's Rotman School of Management wanted to understand why group buying sites that have entered the market recently have enjoyed greater success than those operating a decade ago, such as Mercata and MobShop.

Earlier attempts typically left potential buyers waiting for days before confirming whether or not they had got the offer they had signed up for.

“We think one of the reasons group-buying has been successful recently is because of the short time horizon,” says Rotman Professor Ming Hu, who co-wrote the study with Professor Mengze Shi and PhD student Jiahua Wu. “It allows for a herding effect.”

Another reason is the use of an information structure that discloses to later arrivals how many have already signed onto the deal.

Researchers looked at two ways of designing the purchasing mechanism for a group buy:a simultaneous mechanism, where no one knows how many buyers have come before them, and asequential（连续的） mechanism, where a second group of buyers has the advantage of knowing the size of the first group.

The researchers' analytical（分析的） model shows the most successful mechanism is the sequential one because it eliminates uncertainty for those coming later to the deal, and improves the confidence of those who sign on early, as they're able to track the numbers of those who come after them.

“That boosts confidence,” says Professor Hu, who teaches operations management. Deals for "luxury" services, versus everyday items, work better in a group buy scenario（方案） because they offer consumers a greater benefit.

1.It can be learned from the text that ______.

A．the short time horizon is the reason why group-buying has been successful.

B．a simultaneous mechanism is where a group of buyers has the advantage of knowing how many people have signed up.

C．a sequential mechanism allows a herding effect which boosts the confidence of the buyers.

D．researchers at the University of Toronto's Rotman School of Management carried out an experiment about why group buying sites entered the market successfully, such as Mercata and MobShop.

2.The underlined word “eliminates” in paragraph 7 probably means“______”.

A．to become or to make something greater in amount, number, value

B．to remove or get rid of something

C．to deliberately not include something in what you are doing or considering

D．to make something known to somebody

3.What can be the best title for the passage?

A．Secret for marketing success – boosting confidence.

B．Secret for group-buying mechanism—herding effect.

C．Comparison between a simultaneous mechanism and a sequential mechanism.

D．What others do influences our decisions.

 

Charging your mobile phone might soon be as simple as taking a walk around the block. Scientists have created a new machine that harvest energy from the movement of the knees while walking. Six volunteers wore the devices（装置）on their legs while walking on a treadmill（跑步机）and were able to produce about five watts of electrical power each. That’s enough energy to run 10 mobiles at the same time.

“Since muscles are the powerhouses of the body, my colleagues and I designed our device to generate electricity from the move of the knee joint,” said Max Donelan. “It resembles a knee brace and weighs about 1.5 kilograms including the gearing（传动装置）and generator.”

The apparatus（装置）catches the energy of a person’s movement by connecting an electrical generator to knee moving. When the wearer extends the knee, a gear on the device turns and spins the generator, which builds up energy. When the knee is flexed, the device turns off so as not to tax the wearer. The machine senses moving and knows when to activate itself.

The design allows a person to use the tool without using much additional energy beyond the normal demands of walking. The researchers measured the volunteers’ oxygen intake and carbon-dioxide output to make sure it wasn’t strenuous to use.

People are an excellent source of portable power. An average-sized person stores as much energy in fat as a 1,000-kilogram battery. People recharge their body batteries with food.

The device could be used to power computers in remote areas where electricity is short. The early markets are people whose lives depend on portable power, such as people with artificial limbs (肢体). On the military side, some soldiers have an extreme dependence on batteries these days, so both these groups could benefit.

1．The text is mainly about a new machine that          .

       A．can make your walking easy on a treadmill

       B．can generate enough electricity by walking

       C．can increase the strength of your walking

       D．can offer electricity for your physical practice

2．According to the text, which parts of the body are suitable for the device?

       A．The knees.          B．The ankles.          C．The wrists.          D．The neck.

3．It can be inferred from the text that the amount of electricity from the device directly lies in          .

       A．the speed of your walking                     B．the amount of food you eat

       C．the amount of oxygen intake                 D．the extent of your knees extending

4．Why did the researchers measure the volunteers’ carbon-dioxide output?

       A．To see whether the device is hard to use.

       B．To test the amount of electricity generated.

       C．To tell whether the device has enough source of energy.

       D．To judge what food is useful for the wearers.

5．We can learn from the text that the device          .

       A．is a must for a soldier in the army

       B．will more and more change people’s ways of life

       C．has widely been used in remote areas

       D．is more useful in places with electricity unaccessible