国际科技信息

国际科技信息

美数学家发现最大梅森素数

据美国国家公共电台报道，中央密苏里大学数学家柯蒂斯·库珀领导的研究小组通过参加一个名为“互联网梅森素数大搜索”（GIMPS）的项目，发现了迄今为止最大的梅森素数——2^57885161-1（2的57885161次方减1）。该素数也是目前已知的最大素数，有17425170位，比之前发现的梅森素数多了4457081位数。

美国数学学会发言人迈克 布林说：“超大素数令数学家和计算机科学家感到兴奋。”他认为这是素数探究的一项重大突破。

素数又称质数，是在大于1的整数中，只能被1和其自身整除的数（如2、3、5等）。2300年前，古希腊数学家欧几里德证明素数有无穷多个，并提出一些素数可写成“2^P-1”的形式。迄今为止，人们仅发现48个梅森素数。

梅森素数看似简单，但当指数P值较大时，其探究难度就会很大。计算机的诞生和网格技术的出现，加速了梅森素数探究的进程。1996年初，美国数学家、程序设计师乔治

沃特曼编制了一个梅森素数计算程序，并把它放在网上供人们免费使用，这就是GIMPS项目。人们通过该项目找到了14个梅森素数。

梅森素数在当代具有重大的理论意义和实用价值。其探究推动了“数学皇后”——数论的研究，促进了计算技术、密码技术、网格技术、程序设计技术的发展。另外，梅森素数常用来测试计算机硬件运算是否正确。英国科学家马科斯 索托伊甚至认为梅森素数的研究进展标志着科学发展的里程碑。

World’s largest prime number discovered -- all 17 million digits

If diamonds are a girl’s best friend, prime numbers are a mathematician’s.

And Curtis Cooper at the University of Central Missouri in Warrensburg has just found the biggest, shiniest diamond of them all.

As part of the Great Internet Mersenne Prime Search (GIMPS), a computer program that networks PCs worldwide to collectively hunt for a special type of prime number,Cooper discovered the largest prime number yet late last month:a beast with 17,425,170 digits.

The number -- 2 multiplied by itself 57,885,161 times minus 1, written mathematically as 257,885,161-1 -- is the first prime discovered in four years.

Though there is little mathematical value to finding a single new prime, these rare numbers are prized in their own right by some. "It's sort of like finding a diamond," Caldwell told New Scientist. "For some reason people decide they like diamonds and so they have a value. People like these large primes and so they also have a value."

You can see an abbreviated version of the new prime number,or download all 17,425,170 digits in a massive, 22MB text file.

Finding a new prime number,a number divisible only by itself and one, has little mathematical importance, New Scientist said.Yet the quest for the oddities has long fascinated amateur and professional mathematicians.

The first prime numbers are 2,3, 5, 7, 11, and so on. The number 10 is not prime because it is divisible by 2 and 5, for example. There are an infinite number of primes: The curious or numerologically inclined can peruse a list of the first 50 million primes online.

Mersenne primes like Cooper’s were named for the French monk Marin Mersenne,who studied these numbers more than 350 years ago. The GIMPS project has discovered all 14 of the largest known Mersenne primes.

A Mersenne prime is of the form 2P-1, where the variable P is itself a prime -- making the Mersenne an elite sort of prime,a James Bond among spies. The first Mersenne primes are 3, 7,31, and 127 corresponding to P= 2, 3, 5, and 7, respectively, the GIMPS website explains.

There are only 48 known Mersenne primes.

美国科学家称数百亿年后宇宙有灾难

发现被称作“上帝粒子”的希格斯玻色子是2012年最重要的科学进展之一。不过美国科学家日前表示，基于相关发现中所获数据的计算产生了一个坏消息，即宇宙可能会在数百亿年后面临一场灾难。

“如果你利用我们现在知道的所有物理学（知识）直接计算，这是个坏消息，”美国费米国家加速器实验室理论物理学家约瑟夫 利肯日前在美国科学促进会2013年年会上对媒体表示。美国科学促进会成立于1848年，是世界最大的科学协会之一，《科学》杂志也由其出版。

利肯说，我们生活的宇宙并不稳定，科学界一直希望推算宇宙的长期稳定性，但这需要获得希格斯玻色子和其他亚原子粒子的精确质量，最近的发现提供了相关数据，在此基础上进行的计算显示数百亿年后将有一场灾难——“一个被认为会成为‘替代宇宙’的小空泡将在某处出现，随后逐渐膨胀并最终将我们破坏”。他认为，小空泡将以光速膨胀。

2012年7月4日，欧洲核子研究中心宣布，该中心的两个强子对撞实验项目——ATLAS和CMS均发现一种新的粒子，特性和科学家们寻找多年的希格斯玻色子一致，其质量位于125至126吉电子伏特区间。数据的确定性为5西格玛，即理论物理界可以确认为“发现”的水平。

希格斯玻色子是英国物理学家彼得 希格斯在上世纪60年代的理论研究中预言的粒子，是物质的质量之源，其他粒子在希格斯玻色子构成的“海洋”中游弋，受其作用而产生惯性，最终才有了质量。希格斯玻色子是理论物理“标准模型”中最后一种证明存在的基本粒子，由于它难以寻觅又极为重要，也被称为“上帝粒子”。

Higgs Boson Discovery = Cosmic Doomsday?

If calculations of the newly discovered Higgs boson particle are correct, one day, tens of billions of years from now, the universe will disappear at the speed of light, replaced by a strange, alternative dimension,one theoretical physicist calls“boring.”

Scientists last year announced they had discovered what appeared to be the longsought subatomic particle that accounts for how matter gets its mass.

Analysis is ongoing to fully characterize the particle, known as the Higgs boson, and its related daughter, grand-daughter and cousin particles, all of which are needed to assure scientists that they’ve truly found what was once pure theory.

PHOTOS: Top5 Misconceptions About The LHC

“It sounds too easy -- a particle with no spin and no charge. Like you made it up and yet there it is,” theoretical physicist Joseph Lykken, with the Fermi National Accelerator Laboratory in Batavia, Ill., told Discovery News.

So far, scientists have found nothing to indicate that the particle discovered last year at Europe’s Large Hadron Collider, or LHC, is not the Higgs boson with a mass of about 126 billion electron volts. It turns out that’s a critical number when it comes to the fate of the universe.

“If you use all the physics that we know now and you do what you think is a straightforward calculation, it’s bad news,” said Lykken, who also serves on the LHC science team.

“It may be that the universe we live in is inherently unstable and at some point billions of years from now it’s all going to get wiped out. This has to do with the Higgs energy field itself,” Lykken added,referring to an invisible field of energy that is believed to exist throughout the universe.

PHOTOS: Rapturous Applause for Higgs Boson Scientists

The calculation requires knowing the mass of the Higgs to one percent, as well as the precise mass of other related subatomic particles.

"It's right along the critical line,” said physicist Christopher Hill, also with Fermi.

“That could either be a cosmic coincidence, or it could be that there's some physics that's causing that,” Hill said.

Any life forms still around when the universe ends won’t have to worry about what’s coming -- it will unfold at light speed.

“You won’t actually see it because it will come at you at the speed of light and that’s it,so don’t worry. We know the universe is pretty stable because it’s been around for 13.5 billion years, so even before we did this calculation we knew that.

“This calculation tells you that many tens of billions of years from now there’ll be a catastrophe,” Lykken said.

ANALYSIS: Higgs Boson Likely a 'Boring' Boson

“Essentially, the universe wants to be in different state and so eventually it will realize that. A little bubble of what you might think of an as alternative universe will appear somewhere and then it will expand out and destroy us. So that’ll be very dramatic, but you and I will not be around to witness it,” Lykken told reporters before a presentation at the American Association for the Advancement of Science meeting in Boston this week.

“There will be a new universe, a much more boring universe, so I hope this doesn’t happen,” he added.

英国耗资百万美元造世界首个仿生人

日前，英国科学家利用来自世界各地的最先进人造假肢和器官，制造出一个名为“雷克斯”（Rex，机器人外骨骼的简称）的“仿生人”，这也是世界首个“仿生人”。

“雷克斯”身高近2米，它所使用的假肢和人造器官价值约100万美元（约合623万元人民币），由英国权威机器人专家理查德 沃克和马修 戈登组装而成。“雷克斯”的人工眼包括一个植入了芯片的视网膜和一个置于眼镜上的照相机，相机采集的图像可以转变成电脉冲发送到大脑里，并转化成形状和图案。此外，“雷克斯”全身安装了人造皮肤，体内还装有人工胰脏、肾脏、脾脏等器官和功能性血液循环系统。

“雷克斯”的脚和脚踝是美国麻省理工学院（MIT）的休 赫尔教授开发的，他在一次登山事故中因为冻伤失去了双腿。“人工脚和脚踝上装有感应器，可以读取身体运动进而提供走、跑、跳所需的适量能量，并且它们还能模仿腓肠肌和跟腱的运动，令脚部运动更为自然和灵活，”赫尔教授介绍说。完成后的仿生人可以走路、聊天、并且说出自己的名字，告诉他人其喜欢的时尚品牌并能唱饶舌音乐。

据悉，“雷克斯”是沃克和戈登特意为英国第4频道2月7日播出的一部纪录片打造的，旨在探索现代科技究竟能够达到何种高度。而“雷克斯”的真身也将于同一天在伦敦的科学博物馆展出。

来自瑞士的心理学家贝托尔特·迈耶博士将在纪录片中就“雷克斯”展现的超凡仿生科技展开探讨。迈耶出生时就没有左手，他现在装了一个价值3万英镑（约合29.2万元人民币）的仿生肢。“我们身处的这个时代，科学技术的发展已经让我们能够看到进化极限之外的种种可能性，这既让人感到兴奋，又令人害怕。”

而“雷克斯”的出现也引起了伦理道德方面的争议。波士顿大学的生物伦理和人权教授乔治 安纳斯警告说：“当科技涉及到人类身体时，我们就有了变成‘非人’的危险。需要记住，创造一个新物种，它随时可能反咬我们一口。”

Robot Rex comes face-to-face with the man he is modelled on:Science Museum unveils $1million 'bionic man' with his own heart,blood and lungs

For years it existed only in the wildest realms of science fiction.

But now a team of leading roboticists have created a real bionic man - complete with artificial organs, synthetic blood and robot limbs goes.

The astonishing creation incorporates some of the latest advances in prosthetic technology,as well as an artificial pancreas,kidney, spleen and trachea, and a functional blood circulatory system.

The 6ft 6in (2m) humanoid shares quite a bit in common with Steve Austin, the original 'bionic man' from the cult 1970s TV series the Six Million Dollar Man.

But costing almost £640,000,it is cheaper.

Known as Rex – short for robotic exoskeleton – his hi-tech frame is made up of an array of artificial limbs and organs from around the world.

It was assembled for a new Channel 4 documentary, How To Build A Bionic Man and will go on display at London's Science Museum this week.

The Science Museum exhibit opening on Thursday will explore changing perceptions of human identity against the background of rapid progress in bionics.

In the documentary, to be screened at 9pm on Thursday,experts at the forefront of the research talk to Swiss social psychologist Bertolt Meyer.

Mr Meyer was born without a left hand and has a £30,000 bionic replacement with the ability to grip and twist.

But although his hand is the most advanced on the market,it could soon be obsolete. In the programme Meyer tries out the much more advanced modular prosthetic limb (MPL), which teaches itself how to recognise tiny control signals from the upper arm.

He also meets teams of British scientists who are restoring sight to the blind by implanting microchips in their retinas, and building artificial organs to replace failing lungs, kidneys, pancreases and spleens.

'I've looked around for new bionic technologies, out of personal interest, for a very long time and I think that until five or six years ago nothing much was happening,' said Mr Meyer.

'Then suddenly we are now at a point where we can build a body that is great and beautiful in its own special way.'

David Glover, senior commissioning editor for Channel 4 Factual, said: 'Following Bertolt Meyer, who has a bionic arm himself, as he investigates the reality of building a bionic human takes this brilliantly made documentary into new territory.If what scientists can do now is jaw-dropping, the future is mindboggling.'

The project is supported by a Wellcome Trust People Award which aims to help the public explore biomedical science.

Clare Matterson, director of medical humanities and engagement at the charity, said,quoting from the introduction to the One Million Dollar Man:'Throughout history people have always sought to enhance themselves to overcome disabilities or to become 'bigger, better,stronger and faster'.

Build A Bionic Man hints at the implications these advances may raise for mankind in the future.'

科学家制成彩色高效硅基发光二极管

硅纳米晶体的尺寸仅为几纳米，却具有很高的发光潜力。现在，来自德国卡尔斯鲁厄理工学院（KIT）和加拿大多伦多大学的科研人员借助硅纳米晶体，成功制造出了高效的硅基发光二极管（SiLEDs），其不含重金属，却能够发射出多种颜色的光。相关研究报告发表在近期出版的《纳米快报》杂志上。

硅虽然在微电子和光伏产业占据着主导地位，但长期以来其却一直被认为不适合发光二极管的制造。然而，这在纳米尺度却并非正确，由成百上千的原子构成的微小硅纳米晶体能够产生光线，也具备成为高效光发射器的巨大潜力。迄今为止，硅基发光二极管的制造一直局限于红色的可见光谱范围和近红外线，因此制造可发出彩色光的二极管可谓绝对新颖。

KIT科学家发现，通过采用不同大小的单分散的纳米粒子，能够改变二极管所发出光的颜色。其可由深红色光谱区域调谐至橘黄色的光谱区域，外量子效率亦可达1.1%。值得一提的是，制成的硅基发光二极管具有令人惊讶的长期稳定性，这在此前从未实现过。操作组件寿命的增长是因为只采用了同一尺寸的纳米粒子，这能有效增强敏感的薄膜元件的稳定性，而可导致短路的过大尺寸粒子则被排除在外。

此款彩色硅基发光二极管还具有不含有任何重金属的优势。与其他使用硒化镉、硫化镉或硫化铅的研究小组不同，科研团队此次采用的硅纳米粒子完全不具毒性，而且地球上的硅储量丰富，成本低廉，更有利于硅基发光二极管的进一步发展。

此外，新型发光二极管惹人注目的方面亦在于其发光区域的同质性。研究人员表示，随着液态处理的硅基发光二极管或能以低成本大批量制成，纳米粒子“群体”也将进入新的领域，相关潜力将难以估计，而教科书上有关半导体元件的描述或许也将被改写。

Light from silicon nanocrystal LEDs

Silicon nanocrystals have a size of a few nanometers and possess a high luminous potential.Scientists of KIT and the University of Toronto/Canada have now succeeded in manufacturing siliconbased light-emitting diodes (SiLEDs).They are free of heavy metals and can emit light in various colors.The team of chemists, materials researchers, nanoscientists, and opto-electronic experts presents its development in the Nano Letters journal.

Silicon dominates in microelectronics and photovoltaics industry, but has been considered unsuitable for light-emitting diodes for a long time. However,this is not true for nanoscopic dimensions: Minute silicon nanocrystals can produce light.These nanocrystals consist of a few hundred to thousand atoms and have a considerable potential as highly efficient light emitters, as was demonstrated by the team of Professor Uli Lemmer and Professor Annie K. Powell from KIT as well as Professor Geoffrey A. Ozin from the University of Toronto. In a joint project, the scientists have now succeeded in manufacturing highly efficient light-emitting diodes from the silicon nanocrystals.

So far, manufacture of silicon light-emitting diodes has been limited to the red visible spectral range and the near infrared. As regards the efficiency of silicon diodes emitting red light, researchers from Karlsruhe are already top in the world."Controlled manufacture of diodes emitting multicolor light, however,is an absolutely novelty," explains Florian Maier-Flaig, scientist of the Light Technology Institute (LTI) of KIT and doctoral student of the Karlsruhe School of Optics and Photonics (KSOP). KIT scientists specifically adjust the color of the light emitted by the diodes by separating nanoparticles depending on their size. "Moreover,our light-emitting diodes have a surprising long-term stability that has not been reached before,"Maier-Flaig reports. The increased service life of the components in operation is due to the use of nanoparticles of one size only.This enhances the stability of the sensitive thin-film components.Short circuits due to oversized particles are excluded.

The development made by the researchers from Karlsruhe and Toronto is also characterized by an impressing homogeneity of the luminous areas. The KIT researchers are among the few teams in the world that know how to manufacture such devices. "With the liquidprocessed silicon LEDs that may potentially be produced on large areas as well as at low costs, the nanoparticle community enters new territory, the associated potentials of which can hardly be estimated today. But presumably,textbooks about semiconductor components have to be rewritten," says Geoffrey A. Ozin,who is presently working as a KIT distinguished research fellow at KIT's Center for Functional Nanostructures (CFN).

The SiLEDs also have the advantage that they do not contain any heavy metals. In contrast to cadmium selenide,cadmium sulfide or lead sulfide used by other groups of researchers, the silicon used by this group for the lightemitting nanoparticles is not toxic. Moreover, it is available at low costs and highly abundant on earth. Due to their many advantages, the SiLEDs will be developed further in cooperation with other partners.

美国计划为脑活动绘图 媲美人类基因组计划

奥巴马政府即将出台一项探索人类大脑工作机制、绘制脑活动全图的研究计划。这一计划将耗时10年、投资数十亿美元，可与人类基因组计划相媲美。

这一名为“脑活动绘图”的计划预计最早于3月份公布，参与者包括国家卫生研究院、国防部高级研究项目局、国家科学基金会等联邦机构，霍华德 休斯医学研究所、艾伦脑科学研究所等私营机构，以及神经学家和纳米科学家组成的团队。他们将共同推进对人类大脑近千亿神经细胞的理解，加深对感知、行为以及意识的研究。

科学家抱有很高期望，认为这一计划也有助于加深阿尔茨海默氏症、帕金森氏症等疾病的理解，找到一系列神经性疾病的新疗法，并有望为人工智能领域的进展铺平道路。

“脑活动绘图”计划预计耗时10年，耗资数十亿美元，奥巴马政府下月向国会提交的预算草案将包含这一计划，不过其具体细节目前仍未最终确定。

本月12日，奥巴马在第二任期的首个国情咨文中，将脑研究列为政府应该投资的“好主意”之一。

“我们在人类基因组绘图中每投入1美元，就会给我们的经济带来140美元的回报，”奥巴马说，“今天，我们的科学家为大脑绘图，以揭开阿尔茨海默氏症的答案。他们正开发能修复受损器官的药物，设计可以将电池效能提高10倍的新材料。此时不能在科学和创新领域破坏这些能创造就业的投资。”

人类基因组计划启动于1990年，其目标是绘制人类基因组图谱。在2003年4月提前完成时，这项计划共耗资38亿美元。

Brain Activity Map Project in Planning Stages

The US government is in the planning stages of a massive project to map the activity of the human brain, Story C. Landis, PhD,director of the National Institute of Neurological Disorders and Stroke, confirmed in an interview with Medscape Medical News this week.

President Barack Obama alluded to investing in the "Brain Activity Map" project in his State of the Union address, saying, "Every dollar we invested to map the human genome returned $140 to our economy. Today, our scientists are mapping the human brain to unlock the answers to Alzheimer's;developing drugs to regenerate damaged organs; devising new material to make batteries 10 times more powerful.

"Now is not the time to gut these job-creating investments in science and innovation," he said."Now is the time to reach a level of research and development not seen since the height of the Space Race. We need to make those investments."

Brain Activity Map Project

A "concrete plan" for exactly how the project will unfold has yet to be ironed out, Dr. Landis said. It's also not clear yet how much money the federal government will provide for the project, but a ballpark figure discussed is $300 million a year for a project slated to last 10 years.

Dr. Landis said "work is now ongoing putting together a consortium of federal agencies that would be participating and there is interest from a number of different private foundations."

The Brain Activity Map project will piggyback on the Human Connectome Project, the National Institutes of Health–funded project to create a high-resolution map of the major structural and functional connections in the human brain.

There has been"extraordinary progress" in understanding aspects of human brain organization, Dr. Landis said."The Human Connectome Project is now beginning to produce data in the form of a structural wiring diagram of the human brain and how different areas are connected."

"But what we really need to understand is not just the anatomy but how information gets processed through those connections; in essence, how the human brain actually works. We are never going to get that through wiring diagrams. We really need to know about the function," she explained.

The goals of the Brain Activity Map project, she said,are to develop the tools to "listen in" to neurons as they perform tasks. "How does information go from one brain cell to the next brain cell? How is that information transformed? And ultimately how does processing through the different brain circuits end up giving us behavior, learning, memory,philosophy, etc.?"

This knowledge, Dr. Landis said, should lead to new and better ways of treating neurologic and some psychiatric diseases.

She offered, as an example,deep brain stimulation (DBS) for Parkinson's disease.

DBS, although effective,"is a very elementary way to influence how circuits in the brain function," Dr. Landis explained. "It uses electrical current as sort of a brain pacemaker to change the way circuits involved in the disease work. But imagine if we understood in detail how information was processed through the circuits that control movement for Parkinson's,or emotion for depression, we could potentially develop much better interventions."

Recently, as reported by Medscape Medical News, by use of a sophisticated brain–computer interface, a woman paralyzed from the neck down learned to control a robotic prosthetic arm with her thoughts and perform several activities of daily living.

科学家在南极冰下湖泊首次发现生命

冰川学家John Priscu刚刚结束48小时的曲折旅行，从南极洲回到美国西海岸。即使现在，他还在跟难以忍受的时差作斗争。但是，疲劳并没有掩盖住Priscu的兴奋之情。

数周高强度南极洲野外工作后，Priscu研究小组成为首个在冰雪大陆湖泊深处发现生命的南极考察队。“惠兰斯湖深处确实藏匿着生命，证据显示冰盖下存在一个巨大的湿地生态系统，并且微生物系统活跃。”他说。

这个湖泊的水体面积约有60平方公里，坐落在南极洲西部的罗斯冰架边缘。为了触及这个藏于冰下的湖泊，美国蒙大拿州立大学冰川学家Priscu和同事们不得不钻透800米的冰层。

该考察队使用环境友好型热水钻井技术破冰而入，并继续挖凿，1月28日，他们终于成功到达目的地点。但是，研究人员发现这个水体的深度仅有2米或再深一点，这比地震勘测结果显示的10～25米浅得多。不过Priscu注意到这个湖泊可能存在更深的区域。

Priscu研究小组将一架摄像机沿着钻孔向下探入，以确保这个钻孔的宽度能够允许取样设备安全探入及返回。试验证明钻孔宽度合适，于是Priscu及其同事开始了紧张的取样工作。研究人员共收集到了30升左右的湖水液体，并从湖底部采集到8种沉积岩心样本。

这些宝贵的样本被取出后，Priscu和同事迅速进行现场研究，冰下湖泊的神秘面貌开始在显微镜下慢慢展现。研究发现，无论是惠兰斯湖的水体还是沉积物，都包含大量微生物，而且这些微生物不需要阳光便能够存活。

研究人员的计算结果显示，每毫升湖水中约包含1000个细菌，相当于海洋丰富微生物群的1/10。Priscu还提到，在培养皿中，这些细菌显示出良好的生长态势。

“好极了，这些发现极为重要。”英国布里斯托大学南极研究学者Martin Siegert表示。Siegert也是英国埃尔斯沃斯湖考察队队长，该湖是南极另一个冰下湖泊。去年12月，Siegert带领考察队来到这里，但不幸的是，技术性困难让他们的考察折戟沉沙。

接下来，科学家将进一步研究美国考察队挖掘出的冰下生命，以确定其DNA序列和其他自然特质。“基础工作大约需要至少一个月的时间。”Priscu说，“当然，我们都渴望能够立刻知道，它们是谁，它们的生命周期怎样。”

研究人员希望能够了解冰下微生物的生存策略，以及发现暗含地外生命可能形态的线索。例如，人们认为木卫二存在广阔的地下海洋，在这种极端环境下，可能存在相似的生命。

First Evidence of Life in Antarctic Subglacial Lake

The search continues for life in subglacial Lake Whillans, 2,600 feet below the surface of the West Antarctic Ice Sheet—but a thrilling preliminary result has detected signs of life.

At 6:20am on January 28, four people in sterile white Tyvek suits tended to a winch winding cable onto the drill platform. One person knocked frost off the cable as it emerged from the ice borehole a few feet below. The object of their attention finally rose into sight:a gray plastic vessel, as long as a baseball bat, filled with water from Lake Whillans, half a mile below.

The bottle was hurried into a 40-foot cargo container outfitted as a laboratory on skis. Some of the lake water was squirted into bottles of media in order to grow whatever microbes might inhabit the lake. Those cultures could require weeks to produce results.But one test has already produced an interesting preliminary finding.When lake water was viewed under a microscope, cells were seen: their tiny bodies glowed green in response to DNA-sensitive dye. It was the first evidence of life in an Antarctic subglacial lake.

(A Russian team has reported that two types of bacteria were found in water from subglacial Lake Vostok, but DNA sequences matched those of bacteria that are known to live inside kerosene—causing the scientists to conclude that those bacteria came from kerosene drilling fluid used to bore the hole, and not from Lake Vostok itself.)

In order to conclusively demonstrate that Lake Whillans harbors life, the researchers will need to complete more timeconsuming experiments showing that the cells actually grow—since dead cells can sometimes show up under a microscope with DNA-sensitive staining. And weeks or months will pass before it is known whether these cells represent known types of microbes, or something never seen before. But a couple of things seem likely. Most of those microbes probably subsist by chewing on rocks. And despite being sealed beneath 2,600 feet of ice, they probably have a steady supply of oxygen.

The oxygen comes from water melting off the base of the ice sheet—maybe a few penny thicknesses of ice per year. “When you melt ice, you’re liberating the air bubbles [trapped in that ice],” says Mark Skidmore, a geomicrobiologist at Montana State University who is part of the Whillans drilling, or WISSARD,project. “That’s 20 percent oxygen,”he says. “It’s being supplied to the bed of the glacier.”

In one possible scenario, lake bacteria could live on commonly occurring pyrite minerals that contain iron and sulfur. The bacteria would obtain energy by using oxygen to essentially “burn” that iron and sulfur (analogous to the way that animals use oxygen to slowly burn sugars and fats). Small amounts of sulfuric acid would seep out as a byproduct; that acid would attack other minerals in the sands and sediments of the lake—leaching out sodium, potassium,calcium, and other materials that would accumulate in the water.

小鼠读脑仪在美研制成功

斯坦福大学的科学家开发出一种系统，可以实时观察活鼠大脑活动情况，对研究诸如阿尔茨海默氏症等神经退行性疾病的新治疗手段具有十分重要的作用。该研究发表在近期出版的《自然神经科学》杂志上。

研究人员首先利用基因疗法令老鼠神经细胞表达绿色荧光蛋白，该蛋白对钙离子敏感。当神经元受到刺激时，细胞内充满钙离子，荧光蛋白被激活，整个细胞会发出明亮的绿色荧光，就像一朵灿烂的绿色小烟花在黑色背景下绽放。随后，研究人员在老鼠大脑负责空间和情景记忆的海马体上方植入一个微型显微镜，显微镜与相机芯片相连，并可将数字图片传送到电脑，在电脑屏幕上显示老鼠大脑活动的实时视频。

海马体对环境非常敏感，在不同的环境下会有不同的细胞响应。当老鼠在实验环境的某个特定区域挠墙时，刺激特定的神经元闪烁绿色荧光。当小鼠流窜到别的区域时，绿色荧光会从某个神经元褪色，转而刺激新的神经元细胞发光。科学家在掌握了小鼠行为和神经元之间的关联后，仅仅通过小鼠脑部荧光闪烁的混乱图景，就能够清楚地了解老鼠究竟位于何处。

该研究小组发现，小鼠神经元的刺激模式十分稳定，实验间隔时间长达一月之后，仍可保持不变。而观察相同的细胞对于了解脑部疾病非常重要。如果某一个特定的神经元在测试时发生功能障碍，表明正常神经元已经死亡或出现神经退化疾病。研究人员就可以利用某些实验性的治疗试剂进行治疗，然后在相同刺激条件下，确定神经元能否恢复功能。

目前这项技术尚不能应用于人类，但小鼠模型是研究人类神经退行性疾病新疗法的一个重要起点，该系统将成为临床前研究评估的一种非常有用的工具。目前研究人员已经成立了一个公司，生产和销售该设备。

Stanford researchers develop tool for reading the minds of mice

Stanford scientists have developed a system for observing real-time brain activity in a live mouse. The device could prove useful in studying new treatments for neurodegenerative diseases,such as Alzheimer's.

If you want to read a mouse's mind, it takes some fluorescent protein and a tiny microscope implanted in the rodent's head.

Stanford scientists have demonstrated a technique for observing hundreds of neurons firing in the brain of a live mouse,in real time, and have linked that activity to long-term information storage. The unprecedented work could provide a useful tool for studying new therapies for neurodegenerative diseases such as Alzheimer's.

The researchers first used a gene therapy approach to cause the mouse's neurons to express a green fluorescent protein that was engineered to be sensitive to the presence of calcium ions. When a neuron fires, the cell naturally floods with calcium ions. Calcium stimulates the protein, causing the entire cell to fluoresce bright green.

A tiny microscope implanted just above the mouse's hippocampus – a part of the brain that is critical for spatial and episodic memory – captures the light of roughly 700 neurons.The microscope is connected to a camera chip, which sends a digital version of the image to a computer screen.

The computer then displays near real-time video of the mouse's brain activity as a mouse runs around a small enclosure, which the researchers call an arena.

The neuronal firings look like tiny green fireworks,randomly bursting against a black background, but the scientists have deciphered clear patterns in the chaos.

"We can literally figure out where the mouse is in the arena by looking at these lights," said Mark Schnitzer, an associate professor of biology and of applied physics and the senior author on the paper,recently published in the journal Nature Neuroscience.

When a mouse is scratching at the wall in a certain area of the arena, a specific neuron will fire and flash green. When the mouse scampers to a different area, the light from the first neuron fades and a new cell sparks up.

"The hippocampus is very sensitive to where the animal is in its environment, and different cells respond to different parts of the arena," Schnitzer said."Imagine walking around your office. Some of the neurons in your hippocampus light up when you're near your desk, and others fire when you're near your chair.This is how your brain makes a representative map of a space."

The group has found that a mouse's neurons fire in the same patterns even when a month has passed between experiments. "The ability to come back and observe the same cells is very important for studying progressive brain diseases," Schnitzer said.

For example, if a particular neuron in a test mouse stops functioning, as a result of normal neuronal death or a neurodegenerative disease,researchers could apply an experimental therapeutic agent and then expose the mouse to the same stimuli to see if the neuron's function returns.

Although the technology can't be used on humans, mouse models are a common starting point for new therapies for human neurodegenerative diseases, and Schnitzer believes the system could be a very useful tool in evaluating pre-clinical research.

The work was published Feb. 10 in the online edition of Nature Neuroscience. The researchers have formed a company to manufacture and sell the device.