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A An Essential Scientific Process 一個(gè)至關(guān)重要的科學(xué)過(guò)程一個(gè)至關(guān)重要的科學(xué)過(guò)程 All life on the earth depends upon green plants Using sunlight the plants produce their own food Then animals feed upon the plants They take in the nutrients the plants have made and stored But that s not all Sunlight also helps a plant produce oxygen Some of the oxygen is used by the plant but a plant usually produces more oxygen than it uses The excess oxygen is necessary for animals and other organisms to live The process of changing light into food and oxygen is called photosynthesis Besides light energy from the sun plants also use water and carbon dioxide The water gets to the plant through its roots The carbon dioxide enters the leaves through tiny openings called stomata The carbon dioxide travels to chloroplasts special cells in the bodies of green plants This is where photosynthesis takes place Chloroplasts contain the chlorophylls that give plants their green color The chlorophylls are the molecules that trap light energy The trapped light energy changes water and carbon dioxide to produce oxygen and a simple sugar called glucose Carbon dioxide and oxygen move into and out of the stomata Water vapor also moves out of the stomata More than 90 percent of water a plant takes in through its roots escapes through the stomata During the daytime the stomata of most plants are open This allows carbon dioxide to enter the leaves for photosynthesis As night falls carbon dioxide is not needed The stomata of most plants close Water loss stops If photosynthesis ceased there would be little food or other organic matter on the earth Most organisms would disappear The earth s atmosphere would no longer contain oxygen Photosynthesis is essential for life on our planet A Sunshade for the Planet 地球防曬霜地球防曬霜 Even with the best will1 in the world reducing our carbon emissions is not going prevent global warming It has become clear that even if we take the most strong measures to control emissions the uncertainties in our climate models still leave open the possibility of extreme warming and rises in sea level At the same time resistance by governments and special interest groups makes it quite possible that the actions suggested by climate scientists might not be implemented soon enough Fortunately if the worst comes to the worse2 scientists still have a few tricks up their sleeves3 For the most part they have strongly resisted discussing these options for fear of inviting a sense of complacency that might thwart efforts to tackle the root of the problem Until now that is A growing number of researchers are taking a fresh look at large scale geoengineering projects that might be used to counteract global warming I use the analogy of methadone4 says Stephen Schneider a climate researcher at Stanford University in California who was among the first to draw attention to global warming If you have a heroin addict the correct treatment is hospitalization and a long rehab But if they absolutely refuse methadone is better than heroin Basically the idea is to apply sunscreen to the whole planet One astronomer has come up with a radical plan to cool Earth launch trillions of feather light discs into space where they would form a vast cloud that would block the sun s rays It s controversial but recent studies suggest there are ways to deflect just enough of the sunlight reaching the Earth s surface to counteract the warming produced by the greenhouse effect Global climate models show that blocking just 1 8 per cent of the incident energy in the sun s rays would cancel out the warming effects produced by a doubling of greenhouse gases in the atmosphere That could be crucial because even the most severe emissions control measures being proposed would leave us with a doubling of carbon dioxide by the end of this century and that would last for at least a century more 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 engineers 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 impact 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 university s Centre for Ecology and Conservation said Ants are very effective predators which thrive in huge numbers They re 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 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 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 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 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 ecosystem engineering Ants 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 it is not clear how such disturbance damages the maintenance of ant services to the ecosystem7 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 B Batteries Built by Viruses 病毒電池病毒電池 What do chicken pox the common cold the flu and AIDS have in common They re all disease caused by viruses tiny microorganisms that can pass from person to person It s no wonder1 that when most people think about viruses finding ways to steer clear of2 viruses is what s on people s minds Not everyone runs from the tiny disease carriers though3 In Cambridge Massachusetts4 scientists have discovered that some viruses can be helpful in an unusual way They are putting viruses to work teaching them to build some of the world s smallest rechargeable batteries Viruses and batteries may seem like an unusual pair but they re not so strange for engineer Angela Belcher who first came up with5 the idea At the Massachusetts Institute of Technology MIT in Cambridge she and her collaborators bring together different areas of science in new ways In the case of the virus built batteries the scientists combine what they know about biology technology and production techniques Belcher s team includes Paula Hammond who helps put together the tiny batteries and Yet Ming Chiang an expert on how to store energy in the form of a battery We re working on things we traditionally don t associate with nature says Hammond Many batteries are already pretty small You can hold A C and D batteries6 in your hand The coin like batteries that power watches are often smaller than a penny However every year new electronic devices like personal music players or cell phones get smaller than the year before As these devices shrink ordinary bakeries won t be small enough to fit inside The ideal battery will store a lot of energy in a small package Right now Belcher s model battery a metallic disk completely built by viruses looks like a regular watch battery But inside its components are very small so tiny you can only see them with a powerful microscope How small are these battery parts To get some idea of the size pluck one hair from your head Place your hair on a piece of white paper and try to see how wide your hair is pretty thin right Although the width of each person s hair is a bit different you could probably fit about 10 of these virus built battery parts side to side across one hair These microbatteries may change the way we look at viruses7 C Citizen Scientists Understanding how nature responds to climate change will require monitoring key life cycle1 events flowering the appearance of leaves the first frog calls of the spring all around the world But ecologists can t be everywhere so they re turning to non scientists sometimes called citizen scientists for help Climate scientists are not present everywhere Because there are so many places in the world and not enough scientists to observe all of them they re asking for your help in observing signs of climate change across the world The citizen scientist movement encourages ordinary people to observe a very specific research interest birds trees flowers budding etc and send their observations to a giant database to be observed by professional scientists This helps a small number of scientists track a large amount of data that they would never be able to gather on their own Much like citizen journalists helping large publications cover a hyper local beat2 citizen scientists are ready for the conditions where they live All that s needed to become one is a few minutes each day or each week to gather data and send it3 in A group of scientists and educators launched an organization last year called the National Pheonology4 Network Phenology is what scientists call the study of the timing of events in nature One of the group s first efforts relies on scientists and non scientists alike to collect data about plant flowering and leafing every year The program called Project BudBurst collects life cycle data on a variety of common plants from across the United States People participating in the project which is open to everyone record their observations on the Project BudBurst website People don t have to be plant experts they just have to look around and see what s in their neighborhood says Jennifer Schwartz an education consultant with the project As we collect this data we ll be able to make an estimate of how plants and eommunities5 of plants and animals will respond as the climate changes Clone Farm 克隆農(nóng)場(chǎng)克隆農(nóng)場(chǎng) Factory farming could soon enter a new era of mass production Companies in the US are developing the technology needed to clone chickens on a massive scale1 Once a chicken with desirable traits has been bred or genetically engineered2 tens of thousands of eggs which will hatch into identical copies could roll off the production lines every hour Billions of clones could be produced each year to supply chicken farms with birds that all grow at the same rate have the same amount of meat and taste the same This at least is the vision of the US s National Institute of Science and Technology which has given Origen Therapeutics of Burlingame California and Embrex of North Carolina 4 7 million to help fund research4 The prospect has alarmed animal welfare groups who fear it could increase the suffering of farm birds That s unlikely to put off5 the poultry industry however which wants disease resistant birds that grow faster on less food Producers would like the same meat quantity but to use reduced inputs to get there says Mike Fitzgerald of Origen To meet this demand Origen aims to create an animal that is effectively a clone he says Normal cloning doesn t work in birds because eggs can t be removed and implanted Instead the company is trying to bulk grow6 embryonic stem cells7 taken from fertilized eggs as soon as they re laid The trick is to culture8 the cells without them starting to distinguish so they remain pluripotent says Fitzgerald Using a long established technique these donor cells will then be injected into the embryo of a freshly laid fertilized recipient egg9 forming a chick that is a chimera Strictly speaking a chimera isn t a clone because it contains cells from both donor and recipient But Fitzgerald says it will be enough if say 95 percent of a chicken s body develops from donor cells In the poultry world it doesn t matter if it s not 100 percent he says pluripotent plua ripetent adj 多能的 embryo embrieu n 胚胎 chimera kai miara n 嵌合體 vaccine vaeksiin n 疫苗 Another challenge for Origen is to scale up10 production To do this it has teamed up with11 Embrex which produces machines that can inject vaccines into up to 50 000 eggs12 an hour Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it In future Origen imagines freezing stem cells from different strains of chicken13 If orders come in for a particular strain millions of eggs could be produced in months or even weeks At present maintaining all the varieties the market might call for is too expensive for breeders and k takes years to breed enough chickens to produce the billions of eggs that farmers need Cell Phones Increase Traffic Pedestrian Fatalities 手機(jī)增加交通行人手機(jī)增加交通行人 死亡死亡 Cell phones are a danger on the road in more ways than one Two new studies show that talking on the phone while traveling whether you re driving or on foot is increasing both pedestrian deaths and those of drivers and passengers and recommend crackdowns on cell1 use by both pedestrians and drivers The new studies lead authored by Rutgers University Newark Economics Professor Peter D Loeb2 relate the impact of cell phones on accident fatalities to the number of cell phones in use showing that the current increase in deaths resulting from cell phone use follows a period when cell phones actually helped to reduce pedestrian and traffic fatalities However this reduction in fatalities disappeared once the numbers of phones in use reached a critical mass 3 of 100 million the study found These studies looked at cell phone use and motor vehicle accidents from 1975 through 2002 and factored in4 a number of variables including vehicle speed alcohol consumption seat belt use and miles driven The studies found the cell phone fatality correlation to be true even when including factors such as speed alcohol consumption and seat belt use Loeb and his co author determined that at the current time cell phone use has a significant adverse effect on pedestrian safety and that cell phones and their usage above a critical thresholds adds to motor vehicle fatalities In the late 1980s and part of the 1990s before the numbers of phones exploded cell phone use actually had a life saving effect in pedestrian and traffic accidents Loeb notes Cell phone users were able to quickly call for medical assistance when involved in an accident This quick medical response actually reduced the number of traffic deaths for a time Loeb hypothesizes However this was not the case when cells were first used in the mid 1980s when they caused a life taking effect among pedestrians drivers and passengers in vehicles In those early days when there were fewer than a million phones fatalities increased says Loeb because drivers and pedestrians probably were still adjusting to the novelty of using them and there weren t enough cell phones in use to make a difference in summoning help following an accident he explains The life saving effect occurred as the volume of phones grew into the early 1990s and increasing numbers of cells were used to call 911 following accidents leading to a drop in fatalities explains Loeb But this life saving effect was canceled out6 once the numbers of phones reached a critical mass of about 100 million and the life taking effect increased accidents and fatalities outweighed the benefits of quick access to 911 services according to Loeb Loeb and his co authors used econometric models to analyze data from a number of government and private studies He and his co authors recommend that governments consider more aggressive policies to reduce cell phone use by both drivers and pedestrians to reduce the number of fatalities D Driven to Distraction 分散注意力駕駛分散注意力駕駛 Joe Coyne slides into the driver s eat starts up the car and heads to town The empty stretch of interstate gives way to urban congestion and Coyne hits the brakes as a pedestrian suddenly crosses the street in front of him But even if he hadn t stopped in time the woman would have been safe She isn t real Neither is the town And Coyne isn t really driving Coyne is demonstrating a computerized driving simulator that is helping researchers at Old Dominion University ODU examine how in vehicle guidance systems affect the person behind the wheel The researchers want to know if such systems which give audible or written directions are too distracting or whether any distractions are offset by the benefits drivers get from having help finding their way in unfamiliar locations We re looking at the performance and mental workload of drivers said Caryl Baldwin the assistant psychology professor leading the research which involves measuring drivers reaction time and brain activity as they respond to auditory and visual cues The researchers just completed a study of the mental workload involved in driving through different kinds of environments and heavy vs light traffic Preliminar