1、1第六篇 Making Light of1 SleepAll we have a clock located inside our brains. Similar to your bedside alarm clock， your internal clock2 runs on a 24-hour cycle. This cycle，called a circadian rhythm，helps control whenyou wake，when you eat and when you sleep.Somewhere around puberty，something happens in t
2、he timing of the biological clock. Theclock pushes forward，so adolescents and teenagers are unable to fall asleep as early as they used to. When your mother tells you its time for bed，your body may be pushing you to stay up3 for several hours more. And the light coming from your computer screen or T
3、V could be pushing you to stay up even later.This shift4 is natural for teenagers. But staying up very late and sleeping late can get your bodys clock out of sync with the cycle of light and dark5. It can also make it hard to get out of bed in the morning and may bring other problems，too. Teenagers
4、are put in a kind of a gray cloud6 when they dont get enough sleep，says Mary Carskadon，a sleep researcher at Brown University in Providence，RI 7 .It affects their mood and their ability to think and learn.But just like your alarm clock，your internal clock can be reset. In fact，it automatically reset
5、sitself every day. How? By using the light it gets through your eyes.Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal clocks. For years，researchers thought that the signals that synchronize the bodys clock8 were handled th
6、rough the same pathways that we use to see.But recent discoveries show that the human eye has two separate light-sensing systems. One system allows us to see. The second system tells our body whether its day or night.Graphenes Superstrength1Big technology comes in tiny packages. New cell phones and
7、personal computers get smallerevery year，which means these electronics require even smaller components on the inside.Engineers are looking for creative ways to build these components，and theyve turned their eyes to graphene，a superthin2 material，made of carbon，that could change the future of electro
8、nics.This years Nobel Prize for Physics3 has been awarded to Andre Geim and Kostya Novoselovfrom the University of Manchester4，UK. for the discovery of graphene. Graphene isnt just small,its“the thinnest possible material in this world， ” says Novoselov. He calls it a“wondermaterial. ”Its so thin th
9、at you would need to stack about 25,000 sheets just to make a pile as thick as a piece of ordinary white paper. If you were to hold a sheet of graphene in your fingers5，youd have no idea because you wouldnt be able to see it.Carbon is one of the most abundant elements in the universe. Every known ki
10、nd of lifecontains carbon. Graphene is a sheet of carbon，but only one atom thick. You dont have to lookfar to find grapheme its all around you.If you want this high-tech wonderstuff6，all you need is a pencil，paper and a little adhesivetape. Use the pencil to shade a small area on the paper, and then
11、 apply a small piece of adhesivetape over the area7. When you pull up the tape，youll see that it pulls up a thin layer of some ofthe shading from your pencil. That layer is called graphite，one of the softest minerals in the world.Now stick the same piece of tape on another sheet of paper and pull th
12、e tape up there should be an even thinner layer， this time left on the paper. Now imagine that you do this over and over，until you get the thinnest possible layer of material on the paper. This layer would be only one atom thick，and you wouldnt be able to see it. Graphite is made of layers of graphe
13、ne，so when you get to the thinnest possible layer，youve found graphene.“Life Form Found“ on Saturns TitanScientists say they have discovered hints of alien life1 on the Saturns moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spac
14、ecraft Cassini4,which pointed to,the existence of methane-based form of life on Saturns biggest moon.Scientists have reportedly discovered clues showing primitive alien beings are“breathing“ inTitans dense atmosphere filled with hydrogen.They argue that hydrogen gets absorbed before hitting Titans p
15、lanet-like surface covered with methane lakes and rivers. This,they say,points to the existence of some“bugs“5 consuming the hydrogen at the surface of the moon less than half the size of the Earth.“We suggested hydrogen consumption because its the obvious gas for life to consume on Titan,similar to
16、 the way we consume oxygen on Earth,“says NASA scientist Chris McKay.“If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.“To date,scientists have not yet detected this form of life an
17、ywhere,though there are liquid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin6(minus 290 degrees Farenheit),a methanebased organism would have to use a substance that is liquid as its medium for living
18、 processes, but not water itself. Water is frozen solid on Titans surface and much too cold to support life as we know it.Scientists had expected the Suns interactions with chemicals in the atmosphere to produce a coating of acetylene on Titans surface. But Cassini detected no acetylene on the surfa
19、ce.The absence of detectable acetylene on the Titans surface can very well have a non-biological explanation,said Mark Allen,a principal investigator7 of the NASA Titan team.“Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanation
20、s are addressed,“Allen said. “We 2have a lot of work to do to rule out8 possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results.“*第四十篇 Teaching Math, Teaching AnxietyIn a new study about the way kids learn math in elementary school, t
21、he psychologists at theUniversity of Chicagol1 Sian Beilock and Susan Levine found a surprising relationship between what female teachers think and what female students learn:If a female teacher is uncomfortable with her own math skills, then her female students are more likely to believe that boys
22、are better than girls at math.“If these girls keep getting math-anxious female teachers2 in later grades, it may create a snowball effect on their math achievement3 said Levine. In other words,girls may end up learning math anxiety from their teachers4. The study suggests that if these girls grow up
23、 believing that boys are better at math than girls are,then these girls may not do as well as they would have ifthey were more confident.Just as students find certain subjects to be difficult, teachers can find certain subjects to bedifficult to learn - and teach. The subject of math can be particul
24、arly difficult for everyone.Researchers use the word “anxiety“ to describe such feelings: anxiety is uneasiness or worry.The new study found that when a teacher has anxiety about math, that feeling can influencehow her female students feel about math. The study involved 65 girls,52 boys and 17 first
25、- andsecond-grade teachers in elementary schools in the Midwest. The students took math achievement tests at the beginning and end of the school year, and the researchers compared the scores.The researchers also gave the students tests to tell whether the students believed that a math superstar had
26、to be a boy. Then the researchers turned to the teachers:To find out which teachers were anxious about math,the researchers asked the teachers how they felt at times when they came across math, such as when reading a sales receipt5. A teacher who got nervous looking at the numbers on a sales receipt
27、, for example,was probably anxious about math.Boys,on average,were unaffected by a teachers anxiety. On average,girls with math-anxiousteachers scored lower on the end-of-the-year math tests than other girls in the study did.Plus,on the test showing whether someone thought a math superstar had to be
28、 a boy,20 girls showed feeling that boys would be better at math - and all of these girls had been taught by female teachers who had math anxiety.“This is an interesting study,but the results need to be interpreted as preliminary and in needof replication with a larger sample6,“ said David Geary,a p
29、sychologist at the University of Missouri7 in Columbia.+第四五篇 Small But WiseOn December 14,NASA1 blasted a small but mighty telescope into space. The telescope iscalled WISE and is about as wide around as a trashcan. Dont let its small size fool you:WISE hasa powerful digital camera, and it will be t
30、aking pictures of some the wildest objects2 in the knownuniverse,including asteroids,faint stars,blazing galaxies3 and giant clouds of dust where planetsand stars are born.“Im very excited because were going to be seeing parts of the universe that we havent seenbefore,“said Ned Wright, a scientist w
31、ho directs the WISE project.Since arriving in space,the WISE telescope has been circling the Earth,held by gravity in apolar orbit4(this means it crosses close to the north and south poles with each lap5).Its camera is pointed outward,away from the Earth,and WISE will snap a picture of a different p
32、art of the skyevery 11 minutes. After six months it will have taken pictures across the entire sky.The pictures taken by WISE wont be like everyday digital photographs,however. WISEstands for“Wide-field Infrared Survey Explorer.“As its name suggests,the WISE camera takes pictures of features that gi
33、ve off infrared radiation6.Radiation is energy that travels as a wave. Visible light, including the familiar spectrum oflight7 that becomes visible in a rainbow,is an example of radiation. When an ordinary digitalcamera takes a picture of a tree,for example,it receives the waves of visible light tha
34、t are reflected off the tree. When these waves enter the camera through the lens,theyre processed by the camera,which then puts the image together.Waves of infrared radiation are longer than waves of visible light, so ordinary digital camerasdont see them,and neither do the eyes of human beings. Alt
35、hough invisible to the eye,longerinfrared radiation can be detected as warmth by the skin.Thats a key idea to why WISE will be able to see things other telescopes cant. Not everything in the universe shows up in visible light. Asteroids,for example,are giant rocks thatfloat through space 一 but they
36、absorb most of the light that reaches them. They dont reflect light,so theyre difficult to see. But they do give off infrared radiation, so an infrared telescope like WISE will be able to produce images of them. During its mission WISE will take pictures of hundreds of thousands of asteroids.Brown d
37、warfs8 are another kind of deep-space object that will show up in WISEs pictures.These objects are“failed“ stars 一 which means they are not massive enough to jump start9 the same kind of reactions that power stars such as the sun. Instead,brown dwarfs simply shrink andcool down. Theyre so dim that t
38、heyre almost impossible to see with visible light, but in theinfrared spectrum they glow.Ants Have Big Impact on Environment as “Ecosystem Engineers“Research by the University of Exeter1 has revealed that ants have a big impact on their local environment as a result of their activity as “ecosystem e
39、ngineers“ and predators. The study, published in the Journal of Animal Ecology, found that ants have two distinct effects on their local environment.Firstly, through moving of soil by nest building2 activity and by collecting food they affect the level of nutrients in the soil. This can indirectly i
40、mpact the local populations of many animal groups, from decomposers to species much higher up the food chain.Secondly, they prey on a wide range of other animals, including larger prey which can be attacked by vast numbers of ant workers.Dirk Sanders, an author of the study from the universitys Cent
41、re for Ecology and Conservation, said:“Ants are very effective predators which thrive in huge numbers. Theyre also very territorial3 and very aggressive, defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area.“In this
42、 research, we studied for the first time how big this impact is and the subtleties of it. What we found is that despite being predators, their presence can also lead to an increase in density and diversity of other animal groups4. They genuinely play a key role in the local environment, having a big
43、 influence on the grassland food web,“ Sanders said.The study, carried out in Germany, studied the impact of the presence of different combinations and densities of black garden ants and common red ants, both species which can be found across Europe, including in the UK. It found that a low density
44、of ants in an area increased the diversity and density of other animals in the local area, particularly the density of herbivores and decomposers. At higher densities ants had no or the opposite effect, showing that predation is counteracting the positive influence.Dr Frank van Veen, another author
45、on the study, said:“What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels, but as the number of ants increases, their predatory impacts have the bigger effect thereby counteracting the positive influence via 3ecosystem engineering.“Ants
46、are important components of ecosystems not only because they constitute a great part of the animal biomass5 but also because they act as ecosystem engineers. Ant biodiversity6 is incredibly high and these organisms are highly responsive to human impact, which obviously reduces its richness. However,
47、 it is not clear how such disturbance damages the maintenance of ant services to the ecosystem Ants are important in below ground processes8 through the alteration of the physical and chemical environment and through their effects on plants, microorganisms, and other soil organisms.1第三篇 Germs on Ban
48、knotesPeople in different countries use different types of 1 yuan in China, pesos in Mexico, pounds in the United Kingdom, dollars in the United States, Australia and New Zealand. They may use 2 currencies, but these countries, and probably all countries, still have one thing in common1: Germs on th
49、e banknotes.Scientists have been studying the germs on money for well over2 100 years. At the turn of the 20th 3 , 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 4 one country. In a new study, Frank Vriesekoop3 and other researchers compared the germ populations found on bills of different 5 .Vriesekoop3 is a microbiologist at the University of Ballarat in Australia4. He led the study, which c
