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Prisoners were kept in the most appalling conditions. flexible terrible reasonable serious
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ADHD Linked to Air Pollutants
Children have an increased of attention problems, seen as early as grade school, if their noses inhaled(吸入)a certain type of air pollution when they were pregnant. That’s the finding of a new study. Released when things aren’t burned completely, this pollution is known as polycyclic aromatic hydrocarbons, or PAHs. The biggest sources of these PAHs: the burning of fossil fuels, wood and trash.
Frederica Perera works at Columbia University’s Mailman School of Public Health in New York City. She researches how exposure to things in the environment affects children’s health. In a new study, she and her team studied the exposure to air pollution of 233 nonsmoking pregnant women in New York City. Because burning tobacco can spew(排放)PAHs into the air and lungs, Perera’s team focused on nonsmokers. The researchers wanted to probe(探查)other sources of PAHs, ones that’s would have been hard for an individual to avoid.
The team started by testing the blood of each woman during pregnancy. The reason; Any PAHs in a woman’s blood would also be available to the baby in her womb. Nine years later, the researchers investigated signs of attention problems in those children, now age 9. They asked each child’s mother a series of questions. These included whatever her child had problems doing things that needed sustained(长期的)mental effort, such as homework or games with friends. The scientists also asked if the kids had trouble following instructions or made frequent, careless mistakes. All of these can be symptoms of a disorder called Attention Deficit Hyperactivity Disorder, or ADHD. About one in U. S. children has ADHD.
Among the women studied, traffic and home heating were the primary sources of air pollution exposure, Perera and her team suspect. Some of these women had low levels of PAHs in their blood. Others had high levels. Those with high levels were five times as likely to have children who showed attention problems by age 9. The new findings were published November 5 in the journal PLOS ONE.
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A using photos
B description of the HTML page
C current popular search engines
D document search
E information in images
F machine vision systems
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First Image-recognition Software
1 Dartmouth researchers and their colleagues have created an artificial intelligence software that uses photos to locate documents on the Internet with far greater accuracy than ever before.
2 The new system, which was tested on photos and is now being applied to videos, shows for the first time that a machine learning algorithm(运算法则)for image recognition and retrieval is accurate and efficient enough to improve large-scale document searches online. The system uses pixel(像素)data in images and potentially video—rather than just text-to locate documents. It learns to recognize the pixels associated with a search phrase by studying the results from text-based image search engines. The knowledge gleaned(收集)from those results can then be applied to other photos without tags or captions(图片说明), making for more accurate document search results.
3 “ Over the last 30 years, “ says Associate Professor Lorenzo Torresani, a co-author of the stud-
y, “ the Web has evolved from a small collection of mostly text documents to a modern, massive, fast-growing multimedia data set, where nearly every page includes multiple pictures or videos. When a person looks at a Web page, he immediately gets the gist(主旨)of it by looking at the pictures in it. Yet, surprisingly, all existing popular search engines, such as Google or Bing, strip away the information contained in the photos and use exclusively the text of Web pages to perform the document retrieval. Our study is the first to show that modern machine vision systems are accurate and efficient enough to make effective use of the information contained in image pixels to improve document search. “
4 The researchers designed and tested a machine vision system — a type of artificial intelligence that allows computers to learn without being explicidy programmed — that extracts semantic(语义的)information from the pixels of photos in Web pages. This information is used to enrich the description of the HTML page used by search engines for document retrieval. The researchers tested their approach using more than 600 search queries(查询)on a database of 50 million Web pages. They selected the text-retrieval search engine with the best performance and modified it to make use of the additional semantic information extracted by their method from the pictures of the Web pages. They found that this produced a 30 percent improvement in precision over the original search engine purely based on text.
A Function of the new system
B Improvement in document retrieval
C Publication of the new discovery
D Problems of the existing search engines
E Popularity of the new system
F Artificial intelligence software created
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Dangers Await Babies with Altitude
Women who live in the world’s highest communities tend to give birth to under-weight babies , a new study suggests. These babies may grow into adults with a high risk of heart disease and strokes.
Research has hinted that newborns in mountain communities are lighter than average. But it wasn’t clear whether this is due to reduced oxygen levels at high altitude or because their mothers are under-nourished — many people who live at high altitudes are relatively poor compared with those living lower down.
To find out more, Dino Giussani and his team at Cambridge University studied the records of 400 births in Bolivia during 1976 and 1998. The babies were born in both rich and poor areas of two cities: La Paz and Santa Cruz. La Paz is the highest city in the world, at 3.65 kilometers a-bove sea level, while Santa Cruz is much lower, at 0.44 kilometers.
Sure enough, Giussani found that the average birthweight of babies in La Paz was significantly lower than in Santa Cruz. This was true in both high and low-income families. Even babies born to poor families in Santa Cruz were heavier on average than babies born to wealthy families in lofty La Paz. “We were very surprised by this result, “ says Giussani.
The results suggest that babies born at high altitude are deprived of oxygen before birth. “This may trigger the release or suppression of hormones that regulate growth of the unborn child, “ says Giussani.
His team also found that high-altitude babies tended to have relatively larger heads compared with their bodies. This is probably because a fetus starved of oxygen will send oxygenated blood to the brain in preference to rest of the body.
Giussani wants to find out if such babies have a higher risk of disease in later life. People born in La Paz might be prone to heart trouble in adulthood, for example. Low birth weight is a risk factor for coronary(冠状的)heart disease. And newborns with a high ratio of head size to body weight are often predisposed to high blood pressure and strokes in later life.
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More Rural Research is Needed
Agricultural research funding is vital if the world is to feed itself better than it does now. Dr. Tony Fischer, crop scientist, said demand was growing at 2.5% per year but with modem technologies and the development of new ones, the world should be able to stay ahead.
“The global decline in investment in international agricultural research must be reversed if significant progress is to be made towards reducing malnutrition(营养不良)and poverty. “ he said.
Research is needed to solve food production, land degradation(贫瘠化)and environmental problems. Secure local food supplies led to economic growth which in turn, slowed population growth. Dr. Fischer painted a picture of the world’s ability to feed itself in the first 25 years, when the world’s population is expected to rise from 5.8 to 8 billion people. He said that things will probably hold or improve but there’ll still be a lot of hungry people. The biggest concentration of poor and hungry people would be in sub-Saharan Africa and southern Asia in 2020, similar to the current pattern. If there is any change, a slight improvement will be seen in southern Asia, but not in sub-Saharan Africa. The major improvement will be in East Asia, South America and South-East Asia.
The developing world was investing about 0. 5% , or $8 billion a year, of its agricultural gross domestic product(GDP)on research and developed world was spending 2. 5% of its GDP. Dr. Fischer said more was needed from all countries.
He said crop research could produce technologies that spread across many countries, such as wheat production research having spin-offs(有用的副产品)for Mexico, China or India.
“Technologies still need to be refined for the local conditions but a lot of the strategic research can have global application, so that money can be used very efficiendy. “ Dr. Fischer said.
Yields of rice, wheat ad maize(玉米)have grown impressively in the past 30 years, especially in developing countries. For example, maize production rose from 2 to 8 tones per hectare between 1950 and 1995. But technologies driving this growth such as high-yield varieties, fertilizers , and irrigation, were becoming exhausted. “ If you want to save the land for non-agricultural activities, for forests and wildlife, you’re going to have to increase yield. “ Dr. Fischer said.
