It happens every spring. Flowers come out everywhere on the same day. But how do plants “know” when to flower?

For years, it has been a difficult question for scientists. But a US research group may have finally answered it—the secret lies in a protein(蛋白质)called FKF1. This helps plants to know when the days become long and when they get short. Then they can tell the seasons are changing.

    Researchers found the FKF1 protein when they were studying a plant called Arabidopsis(拟南芥). It is sensitive(敏感的)to sunlight, and can be made active by sunlight.

    Plants produce this protein every day in the late afternoon all year. If there is no light at this time, for example in winter when the sun goes down early, the protein won't be active. But when spring comes and the days get longer, the FKF1 protein can be made active by day light and the plants “know”it is time to flower. “If there is light in the late afternoon, plants will know that the days are getting longer and that it is the best time for flowers to come out,”explained Takato Imaizumi, leader of study. But when conditions are poor for growing, such as during autumn or winter when the weather is cold and days are short, plants won't flower.

    Although researchers have only studied how the FKF1 protein works in the Arabidopsis, they believe that it is the same with many other plants, including crops such as rice and wheat. This could be useful to the agricultural industry.

    "If we can control when flowers come out, we might be able to increase crop production,”Imaizumi said.

    Although cats may be one of the most popular pets today, little is known about how and when humans and cats set up their close relationship.

    The earliest evidence for human–cat interaction dates back to prehistoric Cyprus(史前塞浦路斯), where the remains of a wild cat and a human — dated 9,500 years old — were found buried together

A new study in the Proceedings of the National Academy of Sciences has confirmed the first direct evidence of a human–domestic cat relationship among Chinese farmers 5,300 years ago. Researchers studied the bones of cats, dogs, deer and other animals unearthed in an excavation (挖掘) near a village in Central China. By using some ways, scientists showed that the cats were living on a mostly millet(黍)–based diet, just like the domesticated dogs and pigs from the site.

"The most reasonable explanation for a high consumption of millet–based food is that the cats had formed a stable and mutual relationship with humans and could easily feed on rodents (啮齿动物) around human villages, find leftover food or even have been fed by people intentionally," said Hu Yaowu from the Chinese Academy of Sciences in Beijing, whose research focuses on the relationship between humans and domesticated animals.

    "It is very interesting for us to find the consumption of millet-based foods by the cats, since this kind of evidence had long been missing.” Hu explains. Since cats usually eat meat, such a diet would be unexpected, unless the cats were being fed by people, the study argues. The researchers also found that one of the cats survived to reach old age, implying that it had a safe place to live and enough to eat.

Why the farmers wanted to keep cats nearby or make them "pets" could be answered by other evidence. Chinese archaeologists found some storage containers were specifically designed to keep out rodents — a vermin (害兽) that cats could certainly have helped with.

The simplified theory is that rats were attracted to the food of farmers, and so were harmful to farmers. Cats were attracted to the rats, and so farmers formed a mutually beneficial relationship with cats, taking care of them in return for pest control.

Scientists say life will be very different in 2050.First,there will be no TV channels (频道) . People will choose a programme (节目) from a computer and watch it on the television. We will get information on the computers only.

   Second, water will be a big problem. In many places, people won't have water to drink.

Third, cars will use new and clean fuels and they will go very fast. There will be a computer in every car. And computers will control the cars and there won't be any accidents (事故) .

    It's every parent's worst nightmare there's a fire in the house, the alarms are beeping, but the children are sleeping on. Now scientists have found a better way to rouse slumbering youngsters. Researchers in the US have discovered that playing a child a recording of his mother's voice is about three times more likely to wake him up than a traditional alarm.

    Writing in the Journal of Pediatrics, Smith and colleagues report how they compared the effects of four different smoke alarms on 176 children aged between 5 and 12 years old, none of whom had hearing difficulties or were taking any medication that affected their sleep. While one alarm featured a high-pitched beep the sort of commonly found in households the other three featured the voice of the child's mother calling either the child's name, giving instructions such as: "Wake up! Leave the room! ", or both. Each child slept in a lab-based room that resembled a real bedroom.

    The results show that vocal alarms appear to be more effective than high-pitched beeps. About 90% of children woke for a voice alarm compared with just over 53% for the traditional alarm.

    “High pitched beeping alarms don't wake up children well at all under about 12 years of age, "said Dr Gary Smith, a co-author of the research from the Nationwide Children's hospital in Ohio, although

he said at present it is not known why. He said it was important to look at developing better alarms.

    Prof Niamh Nic Daeid, director of the Leverhulme Research Centre for Forensic Science at the University of Dundee, said the research found a human voice combined with a low-frequency pulsing tone was far more effective in waking up children than a traditional high-pitched alarm. She also noted that more work was needed to explore whether other familiar sounds, such as a dog barking, might also prove effective in rousing children.