2014年6月29日 星期日

Five insights challenging science's unshakable 'truths'

Five insights challenging science's unshakable 'truths'

If you thought dying of loneliness was just an old wives' tale, or that genetic inheritance is fixed – think again. Michael Brooks on science's most unexpected findings
Methyl groups, which affect our genes, often come from what we eat.
Methyl groups, which affect our genes, often come from what we eat. Photograph: Science Photo Library

1 | Lifestyle can change genes

We have come to think that if something is "in our genes", it is our inevitable destiny. However, this is a gross oversimplification. We have each inherited a particular set of genes, but the outcome of that inheritance is not fixed. Our environment, diet and circumstance flood our bodies with molecules that switch the genes on or off. The result can make a huge difference to our destiny – and that of our descendants.
One example of these "epigenetic" changes occurs when a bundle of carbon and hydrogen atoms known as a methyl group attaches itself to the DNA and changes the way its instructions are carried out. The degree of the effect depends on the exact shapes into which the DNA in cells is coiled; sometimes certain genes become more or less exposed to external influences. But it can have major effects: the effect of methyl groups on DNA can make the difference between a foetus being healthy or stillborn.
Methyl groups often come from what we eat. Lack of food seems to have an epigenetic effect, too. A study of Dutch women starved by the Nazis during the second world war – the British actress Audrey Hepburn was among them – has found elevated levels of schizophrenia, breast cancer and heart disease. The data suggest that the alterations to which genes are turned on or off survive at least two generations: the one that suffered in the womb during the famine, and their children.
They may go much further. A 2011 study published by researchers at the Salk Institute in La Jolla, California, demonstrated epigenetic mutationsthat lasted for at least 30 generations in plants. So far, we haven't proved such long-term changes in humans but there are hints that epigenetics cascades through the generations.
A 2001 study traced the long-term effects of nutrition – and malnutrition. Controlling for socioeconomic factors, a boy approaching puberty who overate at the beginning of the last century generally reduced his grandson's life expectancy by a whopping 32 years. Other studies show that if boys start smoking before the age of 11 their sons will be significantly more overweight by age nine than their peers with fathers who only took up smoking later. The only way this can happen is if the act of smoking tobacco triggers some epigenetic change in the way DNA is activated in their sperm.
Standard biological thinking says that the body strips away molecules such as a methyl group from sperm and eggs so that they are "reset" to their default state. However, a study published by Cambridge researchers last year showed that approximately 1% of the changes get through the erasure process unscathed. What you eat, what your mother ate, the age when your grandfather started smoking, the amount of pollution in your neighbourhood – these factors have all been linked to epigenetic changes that get passed down through the generations. Armed with this new insight, we can take far more control of our health – and the health of future generations.

2 | The mind can affect the body

positive and negative moodPositive thinking: the state of our mind affects our physical health. Photograph: Alamy
The US National Oceanographic and Atmospheric Administration has a piece of advice for anyone trying to survive immersion in freezing cold water: "Keep a positive attitude. Will to live makes a difference." Does it really? It seems so.
We know that simple mind tricks can suppress the immune system in animals. First, you teach rats to associate saccharine with a stomach upset by spiking sweet drinks with a drug called cyclophosphamide. Then you just give them saccharine. They will be significantly more susceptible to pathogens than animals given saccharine but no conditioning.
Humans are not exempt from mind-immune system connections. Research carried out on 4,000 people over a 12-year period showed that a man whose wife has just died had a 25% higher chance of dying in those 12 years. The bereaved reported heart and circulatory problems twice as often as people in the control group.
In 2010 a study conducted in the US enumerated the dangers of loneliness. If you have "adequate" social connections, you are 50% more likely to live to the end of a specified period than those who are lonely. In other words, the effect of having good friends is roughly similar to giving up smoking or making a significant cut to your intake of alcohol. A 2012 study, which followed 2,000 US citizens aged 50 and above, found that being chronically lonely was associated with being almost twice as likely to die over the period of the study. Another 2012 study found that elderly people who simply want to live longer do indeed have a better life expectancy regardless of their physical health at the time their desire is expressed.
What used to be dismissed by science as superstition or old wives' tales is now coming to the fore. The state of our minds has a palpable effect on our bodies, meaning that we are finally learning how to protect ourselves better from the worst ravages of illness.
Such knowledge is improving our state of mind too. In 2011 Hasse Karlsson, professor of psychiatry at the University of Helsinki, looked at 20 studies of brain changes induced by psychotherapy and concluded that we are moving towards a situation where we know so much about what psychotherapy does – how our subjective experience can be manipulated to change the physical structures of the brain – that specific types of psychotherapy can be used to target particular brain circuits. As Nobel laureate Eric Kandel has put it: "Psychotherapy is a biological treatment, a brain therapy."
Sigmund Freud started this field in 1895. However, his "Project for a Scientific Psychology" was a miserable failure because we knew too little about the brain. Now, though, we have much better tools with which to explore the mind's effect on the body, and Freud's abandoned programme is finally bearing fruit.

3 | Quantum effects exist in biology

Plants use quantum theory to harvest energy from the sun.Plants use quantum theory to harvest energy from the sun. Photograph: Power & Syred/SPL
If you were designing life from scratch, you'd probably want to avoid the vagaries of quantum theory. Quantum particles such as atoms and electrons do strange things. They can be in two different places at once, or be affected by measurements performed on other particles. Surely such things could only be a hindrance to the smooth functioning of life's processes?
That's certainly what the physicist Erwin Schrödinger said in 1944. Life, he decided, had to be built on a scale that would bury all the weird quantum effects. But Schrödinger was wrong. Plants, for instance, use quantum theory to harvest energy from the sun.
Experiments performed on algae (their light-harvesting equipment is a little more accessible to experiments) have shown that they can channel the sun's energy using "superposition", where the energy travels through the organism using many paths at once. This trick effectively searches all possible paths simultaneously, and finds the quickest and thus most energy-efficient route. That means the energy reaches the plant's storage centre before it dissipates.
There are also hints that smell is a quantum sense. Our noses appear to work by sensing the natural vibration frequencies of the bonds between atoms in molecules. Those frequencies determine whether a smell receptor is switched on and sends a signal to the brain. The best explanation for experimental observations involves an electron using a phenomenon known as quantum uncertainty to tunnel through a seemingly impenetrable barrier. Essentially, it borrows energy from the universe in order to leap across an empty space in the smell receptors and trigger the brain's sense of smell. As long as it returns the energy quickly enough, the electron can use as much as it needs. This "quantum tunnelling" phenomenon is also at the heart of modern electronics."
Then there's the navigation trick birds use for migration. Studies of the European robin (and the robin had to wear a cute little eyepatch during this research) suggest that a particular configuration of a molecule in the robin's retina – a configuration that can only be explained by the rules of quantum theory – allows the bird to sense Earth's magnetic field and thus determine the direction in which it should fly.
We don't know what other quantum feats nature performs, but the fact that these things happen in the warm, wet world of biological material suggests that we are missing a trick. At the moment, we can only access the quantum world if we cool atoms and molecules down to near absolute zero and isolate them from all vibrations and other disturbances. If we can work out how nature functions without such precautions, we might be able to harness quantum theory for ourselves, creating highly efficient solar panels, for instance, or super-sensitive navigation tools.

4 | The universe is a computer (and we are the programmers)

A stellar-mass black holeThe study of black holes has led scientists to question the very nature of reality. Photograph: Nasa
At the forefront of knowledge – the place geneticist Jacob Bronowski once referred to as "the edge of uncertainty" – the biggest thinkers are starting to come to terms with an extraordinary idea. The universe, they say, behaves exactly like a computer, processing and generating information. In this scenario, we, by our conscious and unconscious actions, are playing the role of that computer's programmers.
The first person to think of the cosmos as a human-powered computer was science-fiction author Isaac Asimov. In 1956, in The Last Question, he imagined a situation where two people engage in a bet that ends with humanity absorbed into the intelligent processor that we know as the universe. This was the inspiration behind Douglas Adams's depiction of the Earth as a supercomputer in The Hitchhiker's Guide to the Galaxy.
Truth, though, seems to be stranger than fiction. In the past few years, MIT engineer Seth Lloyd has calculated that a single atom can carry 20 binary digits (bits) of information and that two atoms can collide with an outcome that is entirely equivalent to the information processing that goes on within a computer. The concentration of chemicals within a mix can also store bits: cause these chemicals to react together, and they too can process the information like a computer. Viewed from this perspective, the whole universe is busy performing computations.
According to Lloyd's calculations, a kilogram of matter can perform around a million billion billion billion billion billion operations every second. That processing power is applied to about 10 thousand billion billion billion bits of information. Since time began, Lloyd has calculated, the universe has performed around 10 to the power of 122 operations on 10 to the power of 92 binary digits. What are those operations? We see them aschemistry and physics, as the processes of life and the mechanisms of thought.
There are many more implications to this branch of science – it appears, for instance, that what we call reality is actually a projection of information held at the edge of the universe. The conclusion comes from the study of black holes. One of the sacred laws of physics is that information can't be destroyed. That's a problem when you consider the information contained in things that fall into black holes – unless it remains at the event horizon, which is the spherical "point of no return" surrounding a black hole. That means all the information about what's inside the black hole is held at its edge. If that's true for black holes, it's probably true for the universe as a whole. And that means we are effectively the "holographic projection" of the information held on the spherical shell of the universe.
Whatever the truth we eventually settle on, it seems that life does have some meaning. Where scientists used to say we live out a purposeless existence, it turns out that we, by our actions and minds, are programming the universe. Or, as Carl Sagan put it: "We are a way for the universe to know itself."

5 | Human beings are nothing special

Monkey hand taking peanuts from a human hand Humans are not the only animals that use tools or have personality types. Photograph: Tim Gainey/Alamy
We have been taught to think of ourselves as the pinnacle of creation, but that pinnacle is getting rather crowded. In many cases, crows and chimps can use tools – and sometimes abstract reasoning – better than humans. If it's culture that makes you feel superior, visit the Tanzanian Gombe chimps, Canadian killer whale communities or Australian dolphins: they all show distinct cultural practices in the way they relate with one another, hunt or sing. Animals show personality and morality – elephants can be empathetic or insensitive, rats can be lovers of fair play, spiders can be bold or spineless, chipmunks can be extrovert or shy. Cockroaches have feelings, too, it turns out.
Even the hard facts are letting us down: at the moment, researchers know of only a handful of genes unique to humans; it's thought that, when the count is finished and the numbers are totted up, fewer than 20 of our 20,000 genes will be exclusively human.
It's ironic that biology's love of hard facts is what has delayed our discoveries about the things we share with animals. Darwin was quite convinced of animal personality, compassion and feelings. However, the 1882 publication of George Romanes's book Animal Intelligence, a schmaltzy anthology of readers' tales and anecdotes, sent scientists running from the subject, and it became taboo for nearly a century. That is why Jane Goodall suffered endless insults and derision for her assertions that chimps did not all behave the same way, and that they exhibited moods and personalities, went through childhood and adolescence and grieved at the deaths of their relatives.
One thing does set us apart: our linguistic abilities. These, however, are a quirk of evolution. Although nothing in the animal kingdom is using what we think of as language, gestures used by bonobos and orangutans come close. The fact that we have slightly different anatomical arrangements that allow us to speak is hardly a marker of a fundamental difference.
So we are top of the class, perhaps, but not in a class of our own. This understanding should lead us to re-examine the relationship we have with animals. It is already becoming clear that their personalities affect their ability to survive habitat change. A 2004 study of the three-spined stickleback found that the chemical ethinyl estradiol, which is contained in birth-control pills and has been found in significant concentrations in waterways around the world, makes female sticklebacks exhibit more risky behaviour. The result is lower survival times compared with those in unpolluted waters.
Our responsibility goes beyond habitat pollution and destruction. Our discoveries mean we are already changing the way (and extent to which) we experiment on animals. The next step may be more far‑reaching: how comfortable would we be, for instance, eating a lobster that we knew was terrified by its capture?

2014年6月22日 星期日

Without Shannon's information theory there would have been no internet



Without Shannon's information theory there would have been no internet

It showed how to make communications faster and take up less space on a hard disk, making the internet possible
Shannon’s information theory
Shannon’s information theory
This equation was published in the 1949 book The Mathematical Theory of Communication, co-written by Claude Shannon and Warren Weaver. An elegant way to work out how efficient a code could be, it turned "information" from a vague word related to how much someone knew about something into a precise mathematical unit that could be measured, manipulated and transmitted. It was the start of the science of "information theory", a set of ideas that has allowed us to build the internet, digital computers and telecommunications systems. When anyone talks about the information revolution of the last few decades, it is Shannon's idea of information that they are talking about.
Claude Shannon was a mathematician and electronic engineer working at Bell Labs in the US in the middle of the 20th century. His workplace was the celebrated research and development arm of the Bell Telephone Company, the US's main provider of telephone services until the 1980s when it was broken up because of its monopolistic position. During the second world war, Shannon worked on codes and methods of sending messages efficiently and securely over long distances, ideas that became the seeds for his information theory.
Before information theory, remote communication was done using analogue signals. Sending a message involved turning it into varying pulses of voltage along a wire, which could be measured at the other end and interpreted back into words. This is generally fine for short distances but, if you want to send something across an ocean, it becomes unusable. Every metre that an analogue electrical signal travels along a wire, it gets weaker and suffers more from random fluctuations, known as noise, in the materials around it. You could boost the signal at the outset, of course, but this will have the unwanted effect of also boosting the noise.
Information theory helped to get over this problem. In it, Shannon defined the units of information, the smallest possible chunks that cannot be divided any further, into what he called "bits" (short for binary digit), strings of which can be used to encode any message. The most widely used digital code in modern electronics is based around bits that can each have only one of two values: 0 or 1.
This simple idea immediately improves the quality of communications. Convert your message, letter by letter, into a code made from 0s and 1s, then send this long string of digits down a wire – every 0 represented by a brief low-voltage signal and every 1 represented by a brief burst of high voltage. These signals will, of course, suffer from the same problems as an analogue signal, namely weakening and noise. But the digital signal has an advantage: the 0s and 1s are such obviously different states that, even after deterioration, their original state can be reconstructed far down the wire. An additional way to keep the digital message clean is to read it, using electronic devices, at intervals along its route and resend a clean repeat.
Shannon showed the true power of these bits, however, by putting them into a mathematical framework. His equation defines a quantity, H, which is known as Shannon entropy and can be thought of as a measure of the information in a message, measured in bits.
In a message, the probability of a particular symbol (represented by "x") turning up is denoted by p(x). The right hand side of the equation above sums up the probabilities of the full range of symbols that might turn up in a message, weighted by the number of bits needed to represent that value of x, a term given by logp(x). (A logarithm is the reverse process of raising something to a power – we say that the logarithm of 1000 to base 10 – written log10(1000) – is 3, because 103=1000.)
A coin toss, for example, has two possible outcomes (or symbols) – x could be heads or tails. Each outcome has a 50% probability of occurring and, in this instance, p(heads) and p(tails) are each ½. Shannon's theory uses base 2 for its logarithms and log2(½) is -1. That gives us a total information content in flipping a coin, a value for H, of 1 bit. Once a coin toss has been completed, we have gained one bit of information or, rather, reduced our uncertainty by one bit.
A single character taken from an alphabet of 27 has around 4.76 bits of information – in other words log2(1/27) – because each character either is or is not a particular letter of that alphabet. Because there are 27 of these binary possibilities, the probability of each is 1/27. This is a basic description of a basic English alphabet (26 characters and a space), if each character was equally likely to turn up in a message. By this calculation, messages in English need bandwidth for storage or transmission equal to the number of characters multiplied by 4.76.
But we know that, in English, each character does not appear equally. A "u" usually follows a "q" and "e" is more common than "z". Take these statistical details into account and it is possible to reduce the H value for English characters to less than one bit. Which is useful if you want to speed up comms or take up less space on a hard disk.
Information theory was created to find practical ways to make better, more efficient codes and find the limits on how fast computers could process digital signals. Every piece of digital information is the result of codes that have been examined and improved using Shannon's equation. It has provided the mathematical underpinning for increased data storage and compression – Zip files, MP3s and JPGs could not exist without it. And none of those high-definition videos online would have been possible without Shannon's mathematics.

2014年6月19日 星期四

訪問 美國《科學》主編 (董潔林)



2014/06/18 10:13:48

美國《科學》主編給中國科研者的建議


更多忽東忽西的文章 »
董潔林
幾年,中國大幅度增加了科研投入,希望能夠為人類的科學探索作出與中國的經濟實力相匹配的成就。然而,盡管中國的科研論文數量已躍居全球第二,僅次於美國,但對中國科研論文質量的質疑也甚囂塵上,因此在國際頂級學術期刊發表論文成為很多中國科研人員和科研管理者努力的目標,高校和科研單位不惜重金獎勵在頂級刊物發論文的作者,而科研工作者群體也時常傳出論文造假的醜聞。

從另一方面來說,由於全世界學者發論文需求強勁而國際頂級學術期刊成為極度短缺的奢侈品,因此受到了科研工作者的尖銳批評。基於與一些研究自然科學和社會科學的同事們在這方面的討論,最近我書面訪談了世界頂級學術期刊美國《科學》雜志主編Marcia McNutt博士。McNutt博士很坦誠地回答了學者群體對頂級學術刊物的批評,闡述了她對科研界一些流行的不良行為的看法,並給中國科研者提出了誠懇的建議。下面是對話的完整內容:

董潔林:現在是互聯網時代,學術出版業也被新技術和人們的新生活方式所影響,因此開放獲取變得越來越流行了。作為一家超過130年歷史的學術期刊,《科學》如何面對這種挑戰呢?

McNutt:《科學》認識到優秀論文的數量已經增長了,由於一直受到我們每年預計印刷頁數的局限,我們發表這些傑出研究成果的能力沒有跟上來。因此,最近我們推出了一個嶄新的網上數字版期刊──《科學進步》(Science Advances),這個平台讓我們可以發表更多傑出的研究成果,唯一的要求就是投遞的文章必須是高質量的。另外,《科學進步》 會接受來自更廣泛的學術領域的文章,例如工程、技術以及那些與自然科學有密切聯系和對自然科學有影響的社會科學等。為了服務更多的讀者,這個新期刊採用開放獲取方式發行。

董潔林:在2013年12月,諾貝爾獎獲得者Randy Schekman教授發表了一篇題為“《自然》、《細胞》、《科學》等期刊正在如何損害科學”的文章。該文對這些頂級期刊的主要批評為:其一,“這些期刊精心策劃他們的品牌以達到更多銷售刊物的目的,而不是為了推動最重要的科學研究”;其二,“這些排他性的期刊為自己裝飾了一個名為“影響因子”的噱頭……這些奢侈期刊的編輯深諳此道,因此他們喜歡接受那些內容性感、結論有爭議能夠興風作浪的論文。這種做法影響了科學家的研究選題,推動一些時髦領域形成科研泡沫,而其他一些重要的工作則被耽誤了……” 你們對此如何回應?

McNutt:我們接受論文的政策不受“影響因子”左右,我們編輯部的使命是為讀者提供科學領域裡的那些有趣的、具有開創性的、激發思考的和重要的研究。我們的編輯們敬業地組織嚴密而又專業的同行評議過程,然後從中選擇最後發表在期刊上的論文。不像其他期刊,《科學》僅發表很小一部分論文,因此我們必須很有選擇性。我們認為繁忙的科學家時間很寶貴,他們閱讀科學雜志是因為知道我們很小心地從很多研究領域選擇了很少部分論文發表,而這些研究有可能改變未來科學的軌跡,因此值得他們花時間來閱讀。

《科學》曾多次公開指責“期刊影響因子”作為衡量文章質量這種做法。我們的前任主編Bruce Alberts簽署了“科研評估舊金山宣言”(The San Francisco Declaration on Research Assessment (DORA)),該宣言的目標是停止使用“期刊影響因子”來判斷科學家的工作。另外,Bruce Alberts先生還寫過一篇題為“影響因子的扭曲”的文章),他在文中特別提到了影響因子的誤用,他說:“期刊影響因子的誤用很有破壞性,玩指標遊戲會導致一些期刊不去發表一些重要但少被引用的論文。DORA提出的辦法對於保障科研健康至關重要。”

董潔林:目前,很多國家的學術機構對科研工作者在像《科學》這樣的頂級學術期刊發表論文有很多鼓勵政策,例如獲取更多研究經費,得到雇傭和升職機會,甚至還有現金獎勵。然而這種系統性做法也廣受批評。那麼,你怎麼看這個問題?

McNutt:《科學》完全反對用簡單的代理參數例如論文發表期刊的“影響因子”來替代對一篇論文的實際影響力的適當評審,或者替代對一位研究者完整的貢獻對科學和社會綜合影響力的評審。一些影響因子不高的期刊也可能發表非常重要的論文,反過來也是如此。

董潔林:我注意到《科學》發表越來越多的跨學科和多學科論文,這種文章要求審閱者了解多個學科的前沿工作,從而判斷該文章的新穎性和重要性。你們對此是怎麼做的?

McNutt:論文的確變得越來越跨學科了,融合了大量的材料,時常有很多作者參與一篇論文。與此同時,我們的教育也變得越來越多學科交叉,這代學生(還包括審稿人)能夠更好地面對我們發表的那些復雜的內容。當然,即使是那些知識最為全面的審稿人也難免對一些重要的東西看走眼,論文評審過程中要求大量的補充數據和材料可能讓事情變得更糟糕。對此,我們應該有更高的警覺,我們花很多時間來討論研究結果的可重復性。在這個問題顯著的領域,相應社區開發了一些準則可以幫助評審者去更好地評價研究成果的可靠性。我們也不斷地評估我們的同行評議過程來及時面對新的挑戰。為了增加透明度,我們最近加了一個交叉評審的步驟,在論文最後發表的決定之前,評審們可以閱讀和評論彼此的評審意見。還有,我們編輯部的評審委員會最近增加了一組統計學家,他們的任務是把那些在數據和統計分析上不夠嚴謹的論文標注出來。

董潔林:《科學》有一個新聞欄目,你們認為什麼故事對《科學》具有新聞價值?

McNutt:對《科學》有價值的新聞是那些當前影響科技政策的重要事件、驚人的科學發現、那些值得關注的科學家、科學基金、重大的科研設施、有影響力的報告,和其他影響科研行為、並且讓科學家感興趣和對他們有影響的重要進展。

董潔林:我注意到《科學》發表一些屬於社會科學的論文,例如最近的那篇“大米理論”。你們對什麼樣的社會科學感興趣呢?

McNutt:《科學》會發表那些用嚴謹的定量科學方法來研究社會問題的文章,例如心理學和經濟學。

董潔林:你知道總有一小部分研究者會無視科學界的道德規范,即使像《科學》這樣的頂級期刊也不會幸免這種行為。你們是如何預防像數據作假和剽竊等情況的發生?萬一出現了這些問題,你們又如何處理?

McNutt:《科學》一年會收到約13,000份投稿進行評估,約7%也就是900多篇投稿在同行評議之後會被發表。在這些發表的文章中,只有很少部分(一年3-5篇)論文後來會被撤銷。《科學》對這些事件的處理非常嚴肅,力求盡快修改相應文獻。但是,一般來說,對於相關研究者的調查和處理由他們的雇傭機構進行。因此,《科學》在作出論文撤銷處理之前,會等待相關機構的調查結論看是否真有不良行為。

《科學》在科研道德方面一直保持很高標準,並且增加了新步驟來增加透明度,例如要求數據公開。盡管如此,為了保証讀者看到的發表論文數據的有效性,期刊能做的也就是這麼多了。最終責任人還是作者自己,他們需要完全公開他們的研究方法和研究發現,以及充分討論可能讓他們的研究結果出現錯誤的隱患。

董潔林:《科學》在中國是一份很受尊重的雜志。從來自中國的稿件,你看見什麼趨勢?對於那些希望在《科學》發表論文的中國學者,你有什麼建議?

McNutt:過去幾年,《科學》收到的來自中國的稿件增加了,我們發表的中國稿件增加得更快。也就是說,我們收到的來自中國作者的稿件質量在改善,因此相應的論文接受率在增加。目前中國稿件的接受率與國際稿件接受率基本在同一水平。我能給中國科學家的最好建議是希望他們在向《科學》投稿前,要大量閱讀《科學》上的文章。我也注意到有些來自中國的論文不是帶著客觀冷靜的風格來寫的,這些作者似乎在推銷其研究結果而不是作為一個獨立的研究者去探索科學真理。評審者看到這種情形會對作者的目標生疑,因為他們會認為研究者沒有採取開放的思維方式來從事研究,去客觀地面對任何可能的研究結果。

對於中國科學進展這個話題,我2014年1月有機會與李克強總理在北京會面討論了目前科學發展的狀況。從這個會面中,我感受到了中國將科學發展看作是其未來繁榮的關鍵元素。


Marcia McNutt博士給中國科研工作者的建議讓人深思。科學研究和做產品很不一樣,做產品的人可以懷著偏心和圖利的態度去竭力推銷,而做科學則必須用客觀、理性和開放的態度探索科學真理,並將這個過程的細節公之於眾。發現真理本身,而不是其他,是對科研人員最大的獎勵。然而,她的簡單建議對一個浮躁的、系統性地以功利作為激勵手段的社會來說,是個容易的小調整,還是個不可能完成的任務?

(本文作者董潔林博士是蘇州大學商學院特聘教授,蘇州大學企業創新和發展研究中心主任,清華大學中國科學技術政策研究中心兼職研究員。她於1988年在美國卡內基梅隆大學完成博士學位。文中所述僅代表她的個人觀點。)

2014年6月16日 星期一

英美齒科的革命研究: Regenerating teeth : An enlightened approach


No more fillings as dentists reveal new tooth decay treatment

Scientists in London develop pain-free filling that allows teeth to repair themselves without drilling or injections
Dentist
The new treatment, Electrically Accelerated and Enhanced Remineralisation (EAER), could be available within three years. Photograph: Hermes Morrison 2/Alamy
Scientists have developed a new pain-free filling that allows cavities to be repaired without drilling or injections.
The tooth-rebuilding technique developed at King's College London does away with fillings and instead encourages teeth to repair themselves.
Tooth decay is normally removed by drilling, after which the cavity is filled with a material such as amalgam or composite resin.
The new treatment, called Electrically Accelerated and Enhanced Remineralisation (EAER), accelerates the natural movement of calcium and phosphate minerals into the damaged tooth.
A two-step process first prepares the damaged area of enamel, then uses a tiny electric current to push minerals into the repair site. It could be available within three years.
Professor Nigel Pitts, from King's College London's Dental Institute, said: "The way we treat teeth today is not ideal. When we repair a tooth by putting in a filling, that tooth enters a cycle of drilling and re-filling as, ultimately, each 'repair' fails.
"Not only is our device kinder to the patient and better for their teeth, but it's expected to be at least as cost-effective as current dental treatments. Along with fighting tooth decay, our device can also be used to whiten teeth."
A spinout company, Reminova, has been set up to commercialise the research. Based in Perth, Scotland, it is in the process of seeking private investment to develop EAER.
The company is the first to emerge from the King's College London Dental Innovation and Translation Centre, which was set up in January to take novel technologies and turn them into new products and practices.
King's College is a participant in MedCity, a project launched by the London mayor, Boris Johnson, to promote entrepreneurship in the London-Oxford-Cambridge life sciences "golden triangle".
The chairman of MedCity, Kit Malthouse, said: "It's brilliant to see the really creative research taking place at King's making its way out of the lab so quickly and being turned into a new device that has the potential to make a real difference to the dental health and patient experience of people with tooth decay."



































































































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Regenerating teeth
An enlightened approach
It may be possible to stimulate decayed teeth to repair themselves May 31st 2014 |


Goodbye to all that

REGENERATIVE medicine is a field with big ambitions. It hopes, one day, to repair or replace worn-out hearts, livers, kidneys and other vital organs. Many people, though, would settle for a humbler repair—of their teeth.

Dentistry has too much “drill and fill”, cutting away infected tissue and replacing it with alien, artificial materials. But if work by people such as David Mooney of Harvard University comes to fruition, the days of drill and fill may be numbered. For, as they report in Science Translational Medicine, Dr Mooney and his team have found a surprising way to get dentine, the tissue that underlies a tooth’s enamel coat, to repair itself. They do so by shining a laser beam at it.


Regenerative medicine boils down to the intelligent manipulation of stem cells. A stem cell is one that has the capacity to split asymmetrically so that one daughter remains a stem cell (and can thus go on to perform the same trick) while the other gives birth to a line which proliferates and differentiates into many other sorts of cell. The most famous, and controversial, stem cells are those in early embryos. These can turn into any sort of body cell. Mature tissues such as dentine contain stem cells of more limited capability, which keep up a supply of new specialised cells to replace old ones as they die.

Dr Mooney’s trick is to tickle dentine’s stem cells in a way that encourages them to proliferate and produce more dentine. And that is where the laser comes in. The light it shines creates chemically potent, oxygen-rich molecules such as hydrogen peroxide which go on to activate latent versions of molecules called transforming growth factor–beta 1 (TGF-beta 1). These, in turn, activate dentine’s stem cells and encourage the tissue’s growth.

Dr Mooney and his team have shown that this works in both tissue cultures and actual (rats’) teeth. Moreover, blocking the action of TGF-beta 1 with a drug, or by knocking out the gene that encodes the growth factor’s receptor, stops it happening, which suggests they have understood the mechanism correctly.

This is a preliminary result, and it does not address the question of whether enamel might similarly be repaired. But it is encouraging. Eventually, perhaps, dentists will approach cavities with lasers rather than drills—and the days of fillings will be over. - See more at: http://www.economist.com/news/science-and-technology/21602989-it-may-be-possible-stimulate-decayed-teeth-repair-themselves-enlightened?fsrc=scn%2Ffb%2Fwl%2Fpe%2Fanenlightenedapproach#sthash.vhcWn7xZ.dpuf


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Dentistry has too much "drill and fill", cutting away infected tissue and replacing it with alien, artificial materials. But if work by people such as David Mooney of Harvard University comes to fruition, the days of drill and fill may be numbered. Dr Mooney and his team have found a surprising way to get dentine, the tissue that underlies a tooth's enamel coat, to repair itself http://econ.st/1iz5skc


2014年6月14日 星期六

Earth's Rocks Contain a Hidden Ocean's Worth of Water

Earth's Rocks Contain a Hidden Ocean's Worth of Water

WASHINGTON — If you want to find Earth's vast reservoirs of water, you may have to look beyond the obvious places like the oceans and polar ice caps.
Scientists say massive amounts of water appear to exist deep beneath the planet's surface, trapped in a rocky layer of the mantle at depths between 250 and 410 miles (410 to 660 kilometers).
Image: RingwooditeSTEVE JACOBSEN / NORTHWESTERN U.
Fragments of a blue-colored mineral called ringwoodite can be synthesized in the laboratory. The mineral can include a significant amount of water in its crystal structure, deep below Earth's surface.
But do not expect to quench your thirst down there. The water is not liquid — or any other familiar form like ice or vapor. It is locked inside the molecular structure of minerals called ringwoodite and wadsleyite in mantle rock that possesses the remarkable ability to absorb water like a sponge.
"It may equal or perhaps be larger than the amount of water in the oceans," Northwestern University geophysicist Steve Jacobsen said Friday in a telephone interview. "It alters our thoughts about the composition of the Earth."
"It's no longer liquid water that we're talking about at these great depths. The weight of hundreds of kilometers of rock and very high temperatures above 1,000 degrees Celsius (1,832 Fahrenheit) break down water into its components. And it's not accessible. It's not a resource in any way," Jacobsen added.
Jacobsen said water is taken down into the mantle with minerals during the process known as plate tectonics — the slow, inexorable movement of the colossal rock slabs that make up the Earth's surface.
When the minerals containing this water reach certain depths, they break down in a process called dehydration and release the water to form magmas. Such "dehydration melting" is common in the shallow mantle and forms the source for magmas in many volcanoes.
In a study published in the journal Science, the researchers present evidence that this is also occurring much deeper in the mantle, in a region called the "transition zone" between Earth's upper and lower mantle.
The study combined lab experiments involving synthetic ringwoodite being exposed to conditions simulating the heat and pressure of the transition zone, and observations of events in this zone, based on seismic data from a network of more than 2,000 seismometers across the United States.
A team led by Jacobsen and University of New Mexico seismologist Brandon Schmandt identified deep pockets of magma, a likely signature of the presence of water at those depths.

— Will Dunham, Reuters


科學家新發現:地球內部潛藏巨大海洋

編譯中心 2014年06月13日 18:243577 點擊數
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科學家新發現:地球內部潛藏巨大海洋
地表下方數百公里深處可能有一個「隱藏的海洋」,而且正是地表海洋水量的來源。(取自網路)
美國科學家12日說,地表下方數百公里深處,可能有一個「隱藏的海洋」,水量相當於地表海洋總水量的3倍。此一發現也許有助於解釋地球上海洋的水從何而來:來自地球內部。
 
新墨西哥大學和西北大學的研究人員在《科學》(Science)雜誌上的報告說,這一「隱藏的海洋」位於地球內部410公里至660公里深處、上下地幔(mantle)之間的過渡帶(transition zone),其水分並不是一般熟悉的液態、氣態或固態,而是以水分子的形式存在於一種名為「林伍德石」(ringwoodite)的岩石中。
 
 
研究人員利用遍佈全美的2000多個地震儀分析了500多次地震的地震波。這些地震波會穿透包括地核在內的地球內部,由於水會降低地震波傳播的速度,研究人員可以據此分析地震波穿透的是什麼類型的岩石。
 
結果顯示,就在美國地下660公里深處,岩石發生部分熔融,且從地震波傳播速度減緩來看,這是可能有水存在的信號。
 
與此同時,研究人員在實驗室中合成上下地幔過渡帶中存在的林伍德石,當模擬地下660公里深處的高溫高壓環境時,林伍德石發生部分熔融,就像出汗一樣釋放出水分子。林伍德石由於具有特殊的晶體結構,會像海綿一樣吸引水分子。
 
 
西北大學地球物理學家雅各布森(Steve Jacobsen)說:「我想我們最終找到了整個地球水循環的證據,這或許有助於解釋地球地表大量液態水的存在,幾十年來,科學家一直在尋找這一缺失的深層水。」
 
地球上水的來源有多種說法,一些人認為是彗星或隕石撞擊地球帶來,也有人認為是從早期地球的內部慢慢滲透出來。前一種理論較為盛行,但新發現為後者提供了新的證據。
 
今年3月,加拿大亞伯達大學研究人員在英國《自然》(Nature)雜誌報告說,他們首次發現了來自上下地幔過渡帶的一塊林伍德石,其含水量為1.5%,從而證明有關過渡區含有大量水的理論是正確的。