2009年2月22日 星期日

‘Deep Web’

Exploring a ‘Deep Web’ That Google Can’t Grasp

Jeffrey D. Allred for The New York Times

At the University of Utah, Prof. Juliana Freire is working on DeepPeep, an ambitious effort to index every public database online. by ALEX WRIGHT

Published: February 22, 2009

One day last summer, Google’s search engine trundled quietly past a milestone. It added the one trillionth address to the list of Web pages it knows about. But as impossibly big as that number may seem, it represents only a fraction of the entire Web.

Beyond those trillion pages lies an even vaster Web of hidden data: financial information, shopping catalogs, flight schedules, medical research and all kinds of other material stored in databases that remain largely invisible to search engines.

The challenges that the major search engines face in penetrating this so-called Deep Web go a long way toward explaining why they still can’t provide satisfying answers to questions like “What’s the best fare from New York to London next Thursday?” or “When will the Yankees play the Red Sox this year?” The answers are readily available — if only the search engines knew how to find them.

Now a new breed of technologies is taking shape that will extend the reach of search engines into the Web’s hidden corners. When that happens, it will do more than just improve the quality of search results — it may ultimately reshape the way many companies do business online.

Search engines rely on programs known as crawlers (or spiders) that gather information by following the trails of hyperlinks that tie the Web together. While that approach works well for the pages that make up the surface Web, these programs have a harder time penetrating databases that are set up to respond to typed queries.

“The crawlable Web is the tip of the iceberg,” says Anand Rajaraman, co-founder of Kosmix (www.kosmix.com), a Deep Web search start-up whose investors include Jeffrey P. Bezos, chief executive of Amazon.com. Kosmix has developed software that matches searches with the databases most likely to yield relevant information, then returns an overview of the topic drawn from multiple sources.

“Most search engines try to help you find a needle in a haystack,” Mr. Rajaraman said, “but what we’re trying to do is help you explore the haystack.”

That haystack is infinitely large. With millions of databases connected to the Web, and endless possible permutations of search terms, there is simply no way for any search engine — no matter how powerful — to sift through every possible combination of data on the fly.

To extract meaningful data from the Deep Web, search engines have to analyze users’ search terms and figure out how to broker those queries to particular databases. For example, if a user types in “Rembrandt,” the search engine needs to know which databases are most likely to contain information about fine art (like, say, museum catalogs or auction houses), and what kinds of queries those databases will accept.

That approach may sound straightforward in theory, but in practice the vast variety of database structures and possible search terms poses a thorny computational challenge.

“This is the most interesting data integration problem imaginable,” says Alon Halevy, a former computer science professor at the University of Washington who is now leading a team at Google that is trying to solve the Deep Web conundrum.

Google’s Deep Web search strategy involves sending out a program to analyze the contents of every database it encounters. For example, if the search engine finds a page with a form related to fine art, it starts guessing likely search terms — “Rembrandt,” “Picasso,” “Vermeer” and so on — until one of those terms returns a match. The search engine then analyzes the results and develops a predictive model of what the database contains.

In a similar vein, Prof. Juliana Freire at the University of Utah is working on an ambitious project called DeepPeep (www.deeppeep.org) that eventually aims to crawl and index every database on the public Web. Extracting the contents of so many far-flung data sets requires a sophisticated kind of computational guessing game.

“The naïve way would be to query all the words in the dictionary,” Ms. Freire said. Instead, DeepPeep starts by posing a small number of sample queries, “so we can then use that to build up our understanding of the databases and choose which words to search.”

Based on that analysis, the program then fires off automated search terms in an effort to dislodge as much data as possible. Ms. Freire claims that her approach retrieves better than 90 percent of the content stored in any given database. Ms. Freire’s work has recently attracted overtures from one of the major search engine companies.

As the major search engines start to experiment with incorporating Deep Web content into their search results, they must figure out how to present different kinds of data without overcomplicating their pages. This poses a particular quandary for Google, which has long resisted the temptation to make significant changes to its tried-and-true search results format.

“Google faces a real challenge,” said Chris Sherman, executive editor of the Web site Search Engine Land. “They want to make the experience better, but they have to be supercautious with making changes for fear of alienating their users.”

Beyond the realm of consumer searches, Deep Web technologies may eventually let businesses use data in new ways. For example, a health site could cross-reference data from pharmaceutical companies with the latest findings from medical researchers, or a local news site could extend its coverage by letting users tap into public records stored in government databases.

This level of data integration could eventually point the way toward something like the Semantic Web, the much-promoted — but so far unrealized — vision of a Web of interconnected data. Deep Web technologies hold the promise of achieving similar benefits at a much lower cost, by automating the process of analyzing database structures and cross-referencing the results.

“The huge thing is the ability to connect disparate data sources,” said Mike Bergman, a computer scientist and consultant who is credited with coining the term Deep Web. Mr. Bergman said the long-term impact of Deep Web search had more to do with transforming business than with satisfying the whims of Web surfers.

2009年2月20日 星期五

Breast cancer biology 'changing'

Breast cancer biology 'changing'

By Emma Wilkinson
Health reporter, BBC News

Breast cancer cells
Breast cancer is the commonest cancer in UK women

Lifestyle changes and screening have shifted the type of breast cancers women are diagnosed with over the past couple of decades, research suggests.

Women are now more likely to have hormone-dependent, slow-growing tumours, a comparison of tissue samples from the 1980s and 1990s shows.

The Scottish researchers also found improved survival over time, the British Journal of Cancer reported.

More than 40,000 women are diagnosed with breast cancer in the UK annually.

Previous studies have suggested that breast cancers may be more commonly hormone-dependent than in the past.

It's plausible that lifestyle changes could be influencing the types of breast cancers that women are developing but we will need much larger studies to find out whether this trend is real
Dr Alison Ross, Cancer Research UK

Specifically it is thought that oestrogen-receptor positive cancers may be on the rise.

It is these tumours which respond well to hormone therapy, such as tamoxifen which prevents the disease coming back.

But it has not been clear that numbers were actually on the rise as the ability to detect these types of tumours in the lab may have improved in recent years.

In the latest study, researchers re-examined actual tissue samples - 420 from between 1984 and 1986 and 653 from 1996 to 1997 - saved by two large hospitals in Glasgow.

Those diagnosed in the earlier time period had all presented with symptoms of cancer because screening by mammography had not yet been introduced.

The proportion of cancers which were oestrogen-receptor positive changed significantly from 64.2% to 71.5% over the 10-year period.

And more cancers were diagnosed as grade one - slow-growing tumours, with a decline in the number of grade three - fast-growing tumours.

There was no change over time in the proportion of progesterone or Her-2 positive cancers

Lifestyle

It could be that screening is detecting more oestrogen-receptor positive cancers because they are slow-growing and may be detected before symptoms appear.

But another explanation could be changes in lifestyle factors which increase the risk of hormone-dependent tumours, such as women having babies at an older age, obesity after menopause and use of hormone replacement therapy.

The researchers, led by Dr Sylvia Brown at Crosshouse Hospital in Ayrshire wrote: "There is evidence that the percentage of all children being born to mothers aged 35 years and over is increasing in Scotland and that means BMI and prevalence of obesity are increasing."

She added that if there is a true increase in the proportion of these tumours it has implications for treatment decisions as many clinical trials were carried out in previous decades.

Dr Alison Ross, Cancer Research UK's senior science information officer, said: "It's plausible that lifestyle changes could be influencing the types of breast cancers that women are developing but we will need much larger studies to find out whether this trend is real.

"And it's also not clear whether these results reflect a shift in breast cancer biology or indicate that screening is better at detecting certain cancers.

"If the trend identified in this interesting study is confirmed and continues, it could have an impact on the way doctors apply results from breast cancer studies done decades ago to the treatments in use today."

2009年2月16日 星期一

Submarines smash in ocean

Submarines smash in ocean

HMS Vanguard

A British and French submarine were seriously damaged after a collision underwater, according to reports.

Both the British HMS Vanguard and the French Le Triomphant were carrying nuclear missiles, and were badly damaged by the collision.

It's thought the crash happened at the start of February in heavy seas in the Atlantic Ocean.

Both submarines have technology so that they can see objects underwater, but it doesn't seem to have worked this time.

2009年2月15日 星期日

"危險受體"Cancer 'danger receptor' found

最新科學研究顯示,用人的免疫系統來幫助人體自身對抗癌症,已經向成功又邁進了一步。

英國癌症研究院的科學家發現了一種他們稱之為"危險受體"的細胞,這種細胞也許能刺激人體免疫系統對癌細胞作出反應。

人活著的時候,體內的細胞總是在不斷的死亡,同時又不斷生出新的細胞來接替死去的。

有時候,比如受了傷的時候,細胞就會產生非正常的死亡。

科學家在對一組叫作"受體"的人體細胞進行研究時發現,當這種細胞受刺激後,它們會向大腦發出信號,而大腦會隨即作出反應。

"危險受體"

這一研究確認,受體細胞能夠阻止非正常的細胞死亡。所以研究人員把這種細胞叫作"危險受體"。

領導這一研究的索薩博士說,科學家已經知道,諸如細菌和病毒這樣的污染性有機體,能直接觸發人體免疫系統的反應。

索薩博士說,如果研究發現受傷信號也能刺激免疫系統的話,也許能讓科學家在治療癌症的疫苗和療法方面找到新的路子。

事實上癌症也是可能觸發免疫系統的反應的,因為惡性腫瘤中經常有非正常死亡的集束細胞。

科學家認為,對"危險受體"這種細胞有了更多瞭解後, 也許能夠在利用人體免疫系統對抗自身癌症的研究方面有 很大幫助。


Cancer 'danger receptor' found

Dendritic cell
Dendritic cells alert the rest of the immune system to an invader

A "danger receptor" that may kick-start an immune reaction to cancer in the body has been found by UK researchers.

It picks up signs of cell death caused by injury or tumours and mobilises the body's defences, Nature reports.

The finding may explain why some tumour-killing drugs partly work by setting off an immune response.

Better understanding of the receptor could help develop cancer treatments that harness the immune system, the London Research Institute team said.

Cell death is a normal process in the body which keeps growth and repair ticking over and keeps tissue healthy.

After a 15-year hunt, we've identified the first 'danger receptor' - one which senses abnormal cell death and then triggers an immune response
Dr Caetano Reis e Sousa, study leader

But sometimes there is an abnormal type of cell death called necrosis.

It has been thought for many years that the body somehow senses this abnormal cell death and sets off an immune reaction.

From an evolutionary point of view this would make sense as injury puts the body at risk of infection and an immune response would be a sensible precaution.

However, until now no receptor capable of detecting this abnormal cell death had been found.

The researchers discovered that the DNGR-1 receptor on a type of immune cell called a dendritic cell mobilises an immune response after coming across this abnormal cell death.

Dendritic cells act as messengers, alerting other types of immune cells to kill invaders, such as viruses and bacteria.

Trigger

The researchers said tumours could also trigger this type of immune reaction because they often contain clusters of cells undergoing this type of cell death as they have a limited blood supply.

Dr Caetano Reis e Sousa, lead author based at Cancer Research UK's London Research Institute, said: "After a 15-year hunt, we've identified the first 'danger receptor' - one which senses abnormal cell death and then triggers an immune response.

"The detection of 'danger' could explain some situations when a tumour triggers an immune reaction against itself."

He said manipulating this system could be beneficial in treating cancer but also in other areas, such as preventing rejection in organ transplantation.

"There is a theory that some cancer-killing drugs kill tumour cells in such a way that triggers the immune system against them so they have a double whammy."

Dr Lesley Walker, director of information at Cancer Research UK, said: "The concept of using the body's immune system to fight cancer has been around for decades, but advances in recent years have made this field of research a very exciting one.

"The results of this study are really important scientifically and a step towards understanding how to manipulate the immune system to treat cancer in the future."



Key Jigsaw Piece in Cancer Discovered

Tuesday 6 January

Scientists have discovered a crucial piece in the cancer jigsaw, identifying one key enzyme responsible for allowing cancer to spread, according to a study published in Cancer Cell.

Cancer metastasis, the spreading of cancer from its original location, is responsible for 90 per cent of cancer related deaths.

Lead researcher Dr Janine Erler from The Institute of Cancer Research has discovered that the LOX enzyme is crucial in promoting metastasis and says:

“This research has identified how to prevent a cancer from establishing itself in a new area of the body. This is the crucial missing piece in the jigsaw that scientists have been searching for and is the first time one key enzyme has been identified as being responsible for effectively allowing the cancer to spread.

“LOX works by sending out signals to prepare a new area of the body for the cancer to set up camp. Without this preparation process the new environment would be too hostile for the cancer to grow. If we can interrupt the body’s ability to prepare new locations for the cancer to spread to, we can effectively prevent cancer metastasis.”

The paper looked specifically at how LOX enables the spread of breast cancer, but researchers have evidence that the enzyme is also crucial in the metastasis of other common cancers.

The Institute of Cancer Research hopes to use the discovery of how LOX works to aid the spread of cancer to develop new drug treatments to prevent cancer metastasis.

“Cancer metastasis is very difficult to treat and this new discovery provides real hope that we can develop a drug which will fight the spreading of cancer,” Dr Erler said.

Ends



2009年2月14日 星期六

驗尿可望成為測試前列腺癌新方法

驗尿可望成為測試前列腺癌新方法
前列腺癌細胞
前列腺癌是男性主要癌症之一

美國的醫學專家在分辨良性前列腺疾病和前列腺癌方面的研究取得重大突破。將來驗尿可能是篩測疾病嚴重性的方法。

在《自然》科學期刊發表的報告說,良性前列腺疾病在歐洲和美國的中年男士中相當普遍,但由於沒有可靠的測試分辨良性還是惡性,每年有數以千計的男士接受不必要的手術或放射治療。

研究顯示,三分之一男性的前列腺有少量患癌跡象,但大部分屬於良性和緩慢發展成疾病的情況。只有一小部分是前列腺癌患者。

每年有數以萬計的前列腺癌患者死亡。

目前的測試方法無法分辨良性和惡性前列腺病。為了防患未然,病者一概接受切除手術或放射治療。

現在,研究員發現前列腺癌有一小組的分子是良性前列腺病沒有的。

美國密歇根大學醫學院的欽奈言教授(Professor Arul Chinnaiyan)說,可以按這項發現拓展以驗尿方式篩測病情,醫生將能夠更快更準確地決定治療方法。

欽奈言教授說:"將來的做法可能是先診斷是否有前列腺癌的跡象,接著進一步測試是否需要進行前列腺癌治療、或者動手術、或者放射治療。不用的話,醫生繼續觀察病人的情況,避免施行侵入性的療法。"

欽奈言教授強調,還需要進行更大規模的實驗才能研製出可靠的測試方法,最快也要五年時間。

英國癌症研究機構(Cancer Research UK)回應說,這是一項重要發展,有可能挽救千千萬萬人的性命。

2009年2月10日 星期二

Stress and the Human Brain

Spectrum | 10.02.2009 | 04:30

Stress and the Human Brain

With the deepening global economic crisis, many people are feeling severely stressed.

Stress is more than just a state of mind – it affects memory and planning. Stressful living takes a toll on one's life and health. Correspondent Laura Iiyama has more from Washington, where some researchers have discussed their efforts to understand how stress affects the human brain.


eating science,

Spectrum | 10.02.2009 | 04:30

Restaurant of the Future

Why do people eat minestrone soup for lunch? Or a cheeseburger?

From scientists looking to encourage healthy eating, to food companies wanting to market their products, to people simply trying to control their own waistlines, everyone wants an answer to the same questions: why do we eat what we do and can it be better controlled? Rachel Nolan reports from the latest front of eating science, the Restaurant of the Future in Wageningen, the Netherlands.



2009年2月9日 星期一

高原融冰造成中国大干旱-百年后江河干涸

德语媒体 | 2009.02.09

高原融冰造成中国大干旱-百年后江河干涸

华北和华东数省旱情严重,土地龟裂、作物干枯,中国政府已发出橙色警报。国家主席胡锦涛要求各省全力抗旱、确保农田灌溉。《新苏黎世报》认为提出要求容易,落实起来困难。《法兰克福评论报》指出中国大干旱是青藏高原冰川大面积融化造成的。

《新苏黎世报》说:"提出要求容易,但落实起来困难。因为干旱不仅是天灾,也是人祸。虽然北方因自然原因不时出现干旱,湿润的南方经常遭遇 洪灾,但最近几十年,中国对自己的环境胡乱开发,积下了许多问题。由于水土流失、兴建项目和环境污染,中国本来已经不多的农田逐年减少。

过去几年,水的消耗量剧增,环境专家们已在谈论水危机。城市和工业大量用水使地区的江河失去了平衡,例如,千百年来,黄河是华北的生命之源,黄河流域有四亿人口,但专家们担心,今年黄河的水量只能达到正常年景的60%。

为了减少饮用水对河流的依赖性,中国水文部门越来越多地汲取地下水。因为地下水位不断下降,有些地区甚至每年下降数米,因此打井深度也随之增加。尽 管如此,粮食产量过去几年仍然有所增长。但许多农业科学家认为,这样的产量增长没有可持续性。他们担心,今后几年,大自然的干旱将造成粮食危机。"

中国大旱大涝连续不断的另一个原因是养育江河的青藏高原发生了巨大变化。最近四十年来,号称世界第三极的青藏高原冰川收缩了7%,预计今后25年内,冰川融化速度将加快。《法兰克福评论报》谈了这一问题对中国和东南亚的国计民生产生的负面影响:

"二十亿人的饮用水取自黄河、长江、湄公河、萨尔温江、布拉马普特拉河、恒河和印度河。世界人口最多的国家中国和印度以及巴基斯坦、尼泊尔、孟加拉国、缅甸、越南、老挝、泰国和柬埔寨都依靠这些水源。

"这些国家的降雨不可能多到可以放弃青藏高原雪水的程度,如果青藏高原的冰川日益收缩,江河能提供的饮用水将更为匮乏。农田无法得到灌溉,工业作为最干渴的消费者将面临遭殃的境地,水电站也会很快停止运转。

"'绿色和平'组织的调查报告证实了中国冰川学家姚檀栋的科研结果。调查报告说,仅最近三十年,黄河源头的冰川就已减少了79%。黄河一半的水来自这一地区。过去几十年,这些水不能满足华北地区的需要。黄河的水已很少能一直流入黄海,有时黄河的最后二百公里河段数月无水。

"冰川在继续融化。最多100年,中国的江河就不会有水了。喜欢挖苦说晦气话的人说,在中国成功地用工业废水、粪水和农药把河流全部毒化之前,中国的江河早已干涸了。"

2009年2月8日 星期日

the secret of a hot kiss

From
February 8, 2009

Science finds the secret of a hot kiss

A meeting of lips can spark a chain of chemical changes that really turn your head


IF you always thought you had a special chemistry with your loved one, you may finally have been proved right.

Researchers have found that a passionate kiss unleashes a complex chemical surge into the brain which makes a lover feel excited, happy or relaxed.

There is also speculation that this hormone release may be triggered directly by an exchange of sexually stimulating pheromones in the saliva.

“This study shows kissing is much more complex and causes hormonal changes and things we never thought occurred,” said Wendy Hill, professor of psychology at Lafayette College, Pennsylvania, in an interview.

“We tend to think more about who we are kissing and how it feels, yet there are a lot of other things happening.”

Scientists may have taken a while to catch up on kissing but others have been clear about its impact for centuries.

William Shakespeare described the effect in Romeo and Juliet where, after the couple kiss for the first time, Romeo says: “Sin from thy lips? O trespass sweetly urged! Give me my sin again.”

Hill wanted to find out just what happens to evoke such a powerful emotional response from simply rubbing lips. Her research looked at the impact of kissing on levels of two hormones, oxytocin and cortisol, in 15 male-female couples before and after holding hands and before and after kissing.

Oxytocin is known to be involved in social bonding so the researchers predicted that its levels would rise, while cortisol, a stress hormone, would fall. The results showed cortisol levels fell in both sexes, although oxytocin levels rose in men but fell in women.

This was an unexpected result but Hill and her co-researchers believe the fact that the tests were carried out in an unromantic campus health centre also played a part. Over the past year they have run the tests again in a softer setting complete with romantic background music.

Detailed results will be published at the American Association for the Advancement of Science’s annual conference in Chicago this week but are understood to confirm a close association between kissing and hormone levels.

Other scientists have been looking at the importance of the first kiss, an act long known to have the power to make or break a relationship.

In the 2005 film Hitch, Will Smith plays a New York matchmaker who helps men get dates. He says: “One look, one kiss, that’s all we get . . . to make the difference between happily ever after and, ‘Oh, he’s just some guy I went to some thing with once’.”

Such views are underlined by Professor Susan Hughes, a psychologist at Albright College, Pennsylvania, and co-author of Sex Differences in Romantic Kissing among College Students: An Evolutionary Perspective, whose research suggests that women use kissing as a way of screening potential lovers.

She said: “Females place a lot more importance on the breath and teeth of the person. This shows how well you care for yourself and your hygiene and women are a lot more picky when it comes to that.”

One puzzle is just how kissing might induce hormonal changes of the kind found by Hill. There are clearly psychological factors involved but some researchers suspect saliva contains pheromones, chemical messengers known to be important in other mammals.

In humans the role of pheromones is controversial because we lack organs to detect them. However, Sarah Woodley, an assistant professor at Duquesne University, Pittsburgh, who will speak at the same meeting, believes that people can still detect them via the nose.

Helen Fisher, professor of anthropology at Rutgers University, New Jersey, and author of Why We Love, believes that kissing produces not just a chemical, sexual thrill but can even improve overall health: “If you’re sharing your germs with somebody, you’re boosting your internal defence system.”


與情人熱吻,不僅僅只是嘴唇的碰觸!科學家發現,深情的熱吻,能引發一連串直衝腦門的複雜化學效應,使人心神愉悅放鬆,神經興奮活躍。

星期泰晤士報8日報導,情人「喇舌」時的唾液中含有能激發性慾的費洛蒙,直接刺激荷爾蒙分泌。

美國賓州拉法葉學院心理學教授希爾斯測試15對男女情侶握手及親吻前後,催產素(oxytocin )與皮質素(cortisol)這兩種荷爾蒙激素的分泌量,催產素與人際相處密切相關,皮質素則與壓力有關。

實驗結果顯示,男性的催產素上升,女性下降;皮質素則兩性都下降。希爾斯推測,實驗在健康中心進行不夠浪漫,才造成這種差異。

科學家花一番時間才了解親吻的神秘效應,莎士比亞早在《羅密歐與茱麗葉》便已點出,羅密歐初次吻了茱麗葉後說:「妳的嘴唇傳來了罪惡?甜蜜的侵犯,讓我再犯一次罪吧。」

也有科學家研究初吻是否導致一場戀愛圓滿還是以分手收場。2005年威爾史密斯在電影《全民情聖》中說:「只要一個眼神,一個吻,就能決定是否『從此幸福快樂』。」

紐澤西州羅格斯大學人類學家海倫˙費雪(Helen Fisher)在她的著作《我們為什麼相愛》(Why We Love)中提到,親吻不只帶來化學效應和性快感,還可以促進健康,「你和情人『分享』口中的細菌,免疫力也跟著提升。」

Laser clocks stay spot on for 2bn years

星期泰晤士報8日報導,科學家已成功研發出光學時鐘,可準確計算時間20億年,分秒不差。 光學時鐘(Optical Clock)以雷射偵測電子震動頻率,可切割時間為更小的單位,計時更精準。美國、英國、德國、法國和日本的科學家正在較勁研發,計算宇宙大爆炸至今137億年分秒不差的時鐘預計10年內可問世。 目前全球最先進的時鐘是由美國科羅拉多州圓石市國家標準與技術研究院(NIST)發明,測量汞離子的電子震動頻率,可計算17億年無誤差。之前最標準的原子鐘,則可準確計算8,000萬年;相形之下,普通手錶每月誤差15秒。 光學時鐘將可讓衛星追蹤地球上移動物體的誤差縮減至不到1公尺,並終將使自動汽車和自動駕駛儀十分準確,不需人操控,就可使飛機準確降落。 總部在巴黎的國際度量衡委員會,計劃在2020年淘汰1967年使用至今的原子鐘,換上最新的光學時鐘。國際標準局「時間和頻率委員會」執行秘書艾瑞亞斯表示:「光學時鐘是未來的趨勢,我們會在2015年之前決議是否換成光學時鐘。」


From The Sunday Times
February 8, 2009
Laser clocks stay spot on for 2bn years

SCIENTISTS have developed a new generation of clocks that can keep time without missing a beat in almost 2 billion years.

They are so precise that they will allow satellites to track moving objects to within less than a metre. This could eventually lead to automated cars and an autopilot accurate enough to land a plane without human intervention.

Laboratories in the US, Britain, Germany, France and Japan are now competing to make a clock capable of measuring time so accurately that it would not have lost a second since the Big Bang 13.7 billion years ago. Scientists believe it will be built within a decade.

The new devices are known as optical clocks because lasers “look at” and measure the frequency with which electrons in atoms vibrate. This enables them to divide time into ever tinier increments.

The most advanced clock, created by researchers at the National Institute of Standards and Technology (NIST) in Boulder, Colorado, measures the vibrations of electrons in mercury ions and can go 1.7 billion years without missing a beat. Previously, the most accurate devices were atomic clocks which can measure to an accuracy of one second over 80m years. A normal wristwatch, by contrast, will lose about 15 seconds a month.

The international committee for weights and measures, which is based in Sèvres, in Paris, and sets universal time, is planning to replace its atomic clocks with optical ones by 2020.

Dr Elise Arias, executive secretary of the committee for time and frequency, said: “Optical clocks are the future. They are a very exciting development and we will come to a conclusion on them by 2015.”

The most exciting developments are likely to come in the field of global positioning systems \, which track planes, ships and cars.

GPS devices receive microwave signals sent by satellites and, by measuring the time these take to arrive, can pinpoint the location of an object on Earth to within 10 metres.

Scientists believe that by installing optical clocks on satellites they will be able to refine the level of accuracy to within less than a metre. Such precision could lead to automated motorway driving or landing aircraft on autopilot.

The technology could also enable satellites to map ice caps and mountains more accurately and monitor areas near earthquake faultlines for signs of movement.

The European Space Agency is considering fitting an optical clock to a satellite as part of its cosmic vision programme, which will explore ways of using space for scientific advancement from 2015 to 2025.

Dr Helen Margolis, principal researcher at the National Physical Laboratory, and her colleagues in Teddington, in southwest London, are pioneers of the new technology.

She said: “It is mind- boggling when you think about the accuracy we are getting today. “If you could put these clocks in space that would be useful for measuring the thickness of the ice caps in the Arctic and Antarctic. We probably haven’t even thought of some of the applications these clocks will have yet.”

Scientists have an even more ambitious use for optical clocks. They hope they will enable them to test the most basic laws of physics.

Till Rosenband, a physicist at NIST said: “It would be testing the basic properties of the cosmos. We should be getting to an accuracy where perhaps you could start seeing changes in the basic physics. It’s a strange thing to wrap your mind around. We haven’t seen anything like this yet but it’s exciting to look for.”

The optical clocks will eventually replace atomic clocks, which have provided the standard measure of time since 1967. Atomic clocks, first created by Louis Essen, a British physicist, in 1955, measure microwave radiation emitted by vibrating caesium atoms.

In 1989 Steve Chu, energy secretary in the Obama administration, improved the technology while at Stanford University using caesium atoms to create an “atomic fountain”, which still forms the basis of the most accurate atomic clocks today.

In 2001, NIST developed the first optical clock using lasers instead of microwaves.

It was further improved by British scientists at the National Physical Laboratory in 2004, and last year scientists at NIST developed a clock 21 times more accurate than the best atomic equivalent.

2009年2月7日 星期六

水库可能“诱发”汶川地震

专家:水库可能“诱发”汶川地震
紫坪铺水库
四川紫坪铺大坝蓄积了3亿1千5百万吨水

包括中国地震专家在内的一些地质科学家认为,距汶川地震震中5.5公里处的新建水库的蓄水压力或许触发了附近断层破裂,从而"诱发了"去年5月的四川大地震。

四川省地质局区域地质调查队总工程师范晓在接受BBC中文网电话采访时表示,四川紫坪铺大坝蓄积的3亿1千5百万吨水,可能对地震发生的时间和强度造成了影响。

"诱因"

尽管目前还没有人能证明汶川地震是水库触发的地震活动,但范晓称,巨大的紫坪铺大坝对当地本来就存在的地震活动有干扰,水库蓄水可能改变了地震发生的规模和发生的时间,使地震的强度更大。

但他承认,在下定论之前,需要对有关观测数据做进一步深入的分析。

范晓认为,从以往水库诱发地震的实例分析,紫坪铺水库的迅速蓄水和其水深具备了诱发地震的一切条件。

分析人士说,这一看法令人们开始猜测,人类活动是否要为此次地震承担部分责任。

关联

紫坪铺大坝与汶川大地震之间的联系目前并未得到证实。但是,一些地震科学家已经对此表示关注,并将他们的报告发表在上月出版的《科学》杂志上。

哥伦比亚大学的地球物理灾害研究员克洛斯上月在美国地球物理联合会大会上提出,四川紫坪铺大坝蓄积的数亿吨水给毗邻的北川断层造成了不正常的压力。

尽管克洛斯在报告中没有直接提及任何大坝,但他说,蓄水所产生的作用是地壳运动一年产生的自然应力的25倍。

他认为,当断层最终破裂时,它移动的方式正是永久蓄水所促成的方式。

分歧

不过,也有许多科学家不大认同紫坪铺水库造成地震的这种看法,尽管他们当中有人认为水库是诱因之一。

中国地震局地球物理学家雷兴林认为,水库渗透到断层和2007年12月到2008年5月期间水库水位下降是造成四川大地震成形的"主要因素"。

但雷兴林强调,现在要得出最后结论还为时过早,而且,如果说水库的修筑造成了地震,这种说法有点可笑。

英国地质调查局的地震学家马森也认为,这次地震是地球构造活动的结果,最多只能说紫坪铺水库可能加速了地震发生的时间而已。

四川地质局地质专家范晓在接受BBC中文网采访时说,他同意有没有紫坪铺水库,地震都会发生的观点。

但他指出,水库诱发地震的概念就是,它是发生在有地震活动的区域,由于人工修筑水库,它对地震活动有干扰,干扰的结果,是使地震发生时间是在水库蓄水一段时间之后。

另外,震中就在水库附近,地震的震级可能会大大突破这个地震带以前所记录到的天然地震强度。

他说,这不是水库制造出来的地震,它是本身就有地震,但因为水库蓄水,而且规模是比较大的水库,它足以对地震产生一定的影响。

2009年2月3日 星期二

Smartphone Puts Newborn to Sleep

It's Not the Heat, It's the Tranquillity

Smartphone Puts Newborn to Sleep

By Sindya N. Bhanoo
Special to The Washington Post
Tuesday, February 3, 2009; Page HE01

It was a hot, air-conditioner-worthy day last summer when Chester Marl came home from the hospital. The newborn slept remarkably well through the night.

Once the weather cooled off, his parents stopped running the air conditioner in their Seattle home. Chester bawled for nights at a time.



Smartphone applications, often free or nearly free, include soothing sounds, fitness data and menstrual calculations.
Smartphone applications, often free or nearly free, include soothing sounds, fitness data and menstrual calculations. (Tmsoft (White Noise), Medical Productions (Ifitness), Winkpass Creations (Iperiod))

His parents soon realized he was missing the soothing hum of the machinery.

His father, Brett Marl, who uses the popular iPhone, went to the iTunes Web site in search of a solution and found White Noise.

For 99 cents, the iPhone application offers 40 sounds that aim to soothe you: waves crashing, crickets chirping -- even an air conditioner humming.

For the next four months, the infant slept with his father's iPhone in his crib and White Noise tuned to "air conditioner." The monotonous buzz kept the baby sleeping soundly and his parents happy.

"It's a cool app," Marl said. "It doesn't really do a whole lot, but it was of tremendous value to us."

One of the highlights of having an iPhone, Marl and other users will tell you, is the plethora of applications you can download. Independent developers have created thousands of applications that offer games, music, maps and access to news and weather updates.

Other smartphones, like the BlackBerry and T-Mobile G1, also have applications, but the iTunes online storefront, which lets independent developers sell applications for the iPhone, has resulted in more than 15,000 choices and more than 500 million downloads.

Health care and fitness makes up an entire category, with 745 options that range from the gimmicky to the useful.

They include custom diaries, calorie counters (that track what you eat), pedometers (that track your every footstep) and period trackers (yes, they track your monthly period). There are also apps to track your smoking habit, your blood pressure and your contractions at the end of pregnancy.

Added bonus: There's no commitment involved. Users say they often try apps a few times and then never use them again. Many cost 99 cents, some are even free; at those prices, it's easy come, easy go.

"The key thing to remember about all these things is you can't iPhone your way to your fitness," said Ziv Haskal, an iPhone user and the chief of vascular and interventional radiology at University of Maryland Medical Center. "Unless what you want is really muscular fingers."

One of the most popular fitness applications is iFitness, which for $1.99 offers pictures of hundreds of exercises and lets you log workout information.

Haskal says the portability and functionality of the phone offers many benefits. "If something like iFitness logs information and prods you, then that's good, positive reinforcement," Haskal said. "But looking at pictures won't make you fit."

A free application called Live-strong lets you log your daily workouts and track how many calories you are burning.

It also allows you to log the food you eat every day. Type in "granola," "milk" and "orange," and it instantly logs the calories, making estimates for quantities (a cup of granola, a cup of milk, one orange). It can also pull calorie information for items on popular restaurant menus.

Joseph Misiti, a 25-year-old software engineer who lives in the District, has uses Livestrong to help him count calories, and it has changed his eating habits.

"It's been helpful but depressing," he said. "It's pretty easy to start consuming 4,000 calories without realizing it if you're going out to eat and drinking."

As his New Year's resolution, Misiti gave up his favorite restaurant.

Before . . . the information wasn't as accessible," he said. "As soon as I got this free application, . . . I definitely don't go to Chipotle anymore."

A few applications help women monitor their periods. Cycles is one of the free ones. You input the date of your last period, and the application predicts the dates of your next periods, your ovulation days, and the days you will be most fertile. It's all displayed on a month-by-month calendar.

For $3.99, you can buy iPeriod, which offers similar features but stores more information and offers colorful icons (smiley/sad faces for mood swings and lightning bolts to symbolize cramps).

And for women with infants, there's a swanky application called Baby Tracker for $7.99. When you're about to start nursing, you just tap a button marked left or right breast to start a timer that records your nursing times and dates.

Marl and his wife tried it out but then decided against it. "I thought, if we need an iPhone or a spreadsheet to track how we're feeding our kid, we're doing something wrong," he said.

Here's a small sampling of what else is available in the health-care and fitness category:

Lose It! (free): Lets you enter weight-loss goals, track your calorie intake, and calculate how many calories you've burnt through exercise.

Fast-Food Calorie Counter ($2.99): Offers nutritional information on thousands of menu items at 49 restaurant chains.

Vision (99 cents): Offers "eye exercises" and optical illusion tests, and lets you take tests to check for color blindness and astigmatism.

Yoga Stretch ($1.99): Plays an audio yoga session as an instructor guides you through poses. The application also displays yoga positions in sessions that last from one to 60 minutes.

Salt Shaker (free): Simulates salt falling out of a shaker when you jiggle your phone. Good for those on a low-sodium diet, perhaps?

My Life Record ($49.99): Lets you manage and access medical records including doctor information and images such as X-rays, ultrasounds and electrocardiograms. The company says it uses industry-standard encryption to keep the data safe.

Haskal said that while most health and fitness applications seem marginally useful, applications such as My Life Record show great promise.

"If your phone can access a list of your medications and maintain your medical records, and if it's password-protected and secured, it's as good as having it all in your wallet," he said. "That's something I want from every one of my patients."

Joseph O'Brien, an orthopedic surgeon at George Washington University Hospital, said calorie-counting and exercise-tracking applications might be very useful.

"If one of my patients had an iPhone, that could be a useful way to keep track of progress," he said.

O'Brien envisages an increase in the iPhone's usage in health care.

"Because it's a small computer, it's going to become more pertinent," O'Brien said.



2009年2月2日 星期一

The Information Highway and the Blind

Spectrum | 03.02.2009 | 04:30

The Information Highway and the Blind

Languages aren’t just spoken, but are also written down in forms ranging from poems and novels to newspapers and instruction manuals. For blind people, accessing these written forms of communication can present an enormous hurdle.

This is because the written word has to be translated into Braille or spoken onto an audio tape, all of which takes time and money. But the combination of screen reading software for computers and the large amounts of information available on the Internet is now opening up written language to blind people. Even though the software is continually improving, however, bad web design is still making it difficult for the blind to fully use the information highway. Kate Hairsine reports.

New Technology and Road Safety in Europe

Spectrum | 03.02.2009 | 04:30

New Technology and Road Safety in Europe

It's safer than ever to drive a car in Europe. The number of fatal traffic accidents has gone down by half in the last thirty years, although there are three times as many cars on the road today.

But European officials and some car manufacturers are not satisfied with current road safety levels. Brussels has set ambitious new targets to cut the number of traffic accidents in half by 2010, and they're turning to futuristic new technologies to meet these goals. Alex Bakst explores the potential of new gadgets to improve safety for European drivers.

2009年2月1日 星期日

Study Can't Pinpoint Extent of Lead Exposure

Study Can't Pinpoint Extent of Lead Exposure

Several Factors Determine Any Harm to Children's IQ; Experts View Public Health Impact as Slight

Washington Post Staff Writer
Saturday, January 31, 2009; Page B01

IQ 損失多少分等說法是假科學

Scientists say they might never know how many children were harmed when lead levels in the District's water spiked early this decade. The number could be as few as 700 or as many as tens of thousands.

This Story
View All Items in This Story
View Only Top Items in This Story

The ultimate effects depend not only on how much of the toxic metal the children ingested but also how vulnerable they were as a consequence of genetics, their home environment and their experience in school.

The effects could include the loss of two to three IQ points and a higher risk for behavioral problems, even in children whose bloodstream lead stayed below the threshold of concern set by federal health officials.


But at the exposure levels experienced by the District's children, the public health consequences are likely to be very slight, even under the most pessimistic assumptions, according to several experts as well as published studies.

A new study published this week has raised questions about the health effects on children resulting from the District's drinking water crisis of 2001 through 2004.

Unlike some toxic substances, there is no known "safe" level for lead exposure. The official threshold is 10 micrograms per deciliter of blood. But even at more modest increments above zero, researchers have found small effects on intelligence as measured by IQ.

"At these levels, the effects are subtle," said Howard Frumkin, director of the National Center for Environmental Health at the Centers for Disease Control and Prevention. "They are detectable in population studies but generally not in individual children."

Studies have shown that lead exposure explains less than 4 percent of the variation in intelligence among individuals. In contrast, societal and parenting factors account for more than 40 percent.

Just how lead damages the brain is not completely understood. Damage might arise from lead's ability to substitute for calcium, which is involved in the storage and release of neurotransmitters in the brain, among many other actions.

But although the exposure's health effects might be small in magnitude, they could be wide in scope.

"We suspect that there are thousands, and possibly tens of thousands, of children who have experienced harm as a result of increased lead exposure" in Washington, said Bruce P. Lanphear, a doctor and lead-poisoning expert at Simon Fraser University in Vancouver, British Columbia.

One of the authors of the new study said she is advising parents that in the worst-case scenario a child might have lost three to four IQ points.

"That is all I can say," said Dana Best, a pediatrician and epidemiologist at Children's National Medical Center. "With enrichment, with a good school environment, it is likely that the loss will not affect your child in a significant way."

There are three reasons it is hard to gauge the health effects of the lead in the District's drinking water, which rose in the second half of 2001 and returned to normal by 2005.

First, it is impossible to know how many children were exposed and for how long. Lead levels in water fluctuate by neighborhood, by day and even by the time of day. Water consumption also varies, with some families drinking only tap water and others using bottled water all or part of the time.

Parenting practices are also important factors. Babies given formula mixed with tap water get far more lead than breast-fed infants.


ad_icon

Second, research has shown that on a microgram-by-microgram exposure, lead has a greater effect on IQ at low concentrations than at high concentrations. In other words, the brain is more sensitive to small doses than to large ones, even though large ones ultimately do more damage.

The consequence of this counterintuitive fact is that a child whose blood lead rises from two micrograms to five micrograms for several years might not only be affected, but that the effect might also be more exaggerated than one would expect.

The third reason it is impossible to know the effect of a population-wide exposure like the "lead plume" in Washington's drinking water is that vulnerability varies from person to person.

Three genes are thought to play a role in heightening or dampening a person's risk of suffering lead toxicity. Probably more important is the capacity of attentive parents, interesting activities and good schools to counteract the damaging effects.

In the new study, published in the journal Environmental Science & Technology, researchers examined more than 28,000 blood-lead tests done at Children's from 1999 to 2007. They used the upward trend of tests in the "elevated" range to deduce what might have been happening in the city as a whole during the years that water lead levels rose and then fell back.

The fraction of tests in children less than 16 months of age that were above 10 micrograms -- the official threshold of concern -- rose from 0.5 percent to 4.8 percent in the second half of 2001, about six months after an additive was put in Washington's water that unintentionally leached lead out of pipes. By 2004, the fraction of Children's lead tests that were elevated was back down to 1.8 percent.

By one estimate, about 46,000 District children younger than age 6 were exposed to elevated lead through drinking water in 2004.

Using a mathematical model, researchers estimated that 517 children younger than age 2 1/2 had elevated blood lead levels in 2003 "due to high water lead levels," and that 342 had elevated levels in 2004 from the same exposure.

A different model, developed by the U.S. Environmental Protection Agency, estimated 170 "excess" cases of elevated blood lead in same age group in 2003. (Estimates for 2004 using that model weren't available.)

The two sets of results are close enough that they suggest a ballpark estimate for the number of children whose elevated lead was attributable to the water problem.

"But the sad reality is that because there is so little blood lead data for children age 0 to 1 years of age, we can never know the exact numbers," one of the authors, Marc Edwards of Virginia Tech, said in an e-mail. "I know that this answer is extremely frustrating for us . . . and DC consumers."

So what might the consequences of that exposure be?

A study published in the New England Journal of Medicine in 2003 attempted to answer that.

Researchers there examined the experiences of 172 children in Rochester, N.Y. They found that when a child's childhood-long blood-lead level was 10 micrograms, his or her IQ was on average 7.4 points lower than a child with a lifelong zero reading.

The decline in IQ in children with blood-lead readings of 30 micrograms compared with those with 10-microgram levels was not as steep: about three IQ points. However, children at that level had suffered the effect of the zero-to-10-microgram rise, so the overall damage was greater.

An analysis of seven studies from four countries (the United States, Mexico, Australia and Yugoslavia) found a similar effect, although not as dramatic.

Those studies found that when blood lead rose from 2.4 to 10 micrograms, the IQ loss was 3.9 points. When it rose from 10 to 20, there was a loss of another 1.9 IQ points.