| 2006年09月28日 Nature中英文摘要 | 点击： 作者： 来源： 时间： 2006-11-11 本站论坛
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Volume 443 Number 7110 pp371-480 (28 September 2006)
September 28, 2006
封面故事：固体中或室温下的玻色－爱因斯坦凝聚
玻色－爱因斯坦凝聚（BEC）是首次于1924年假设存在的一种物质形式，已经在超低温度下、在稀释原子气体中进行了著名的演示试验。现在，科学家正在为寻找BEC能够出现的固态体系做很多努力。理论上，半导体微腔（光子被束缚在其中，并与电子激发态耦合在一起，导致偏振子的生成）有可能允许BEC在低温学中标准的温度下出现。现在，Kasprzak等人报告了偏振子在这样一个微腔中被激发的实验。 在超过一个临界偏振子密度时，一个宏观量子相的自发形成就会出现，代表一种固态的BEC。如果光子与固态激发的耦合足够强的话，BEC还应可能在更高温度下出现。Demokritov等人已经做到了这一点，他们在室温下、在一种磁振子（一种类型的磁激发）气体中观测到了BEC。封面所示为BEC开始形成时的粒子-粒子相互作用。
Page: 409
September 28, 2006
与干细胞衰老调控有关的蛋白
在本期Nature中，三个实验室分别报告了一种蛋白的发现。该蛋白专门在干细胞中调控衰老。 这个发现可帮助回答一个根本问题：为什么哺乳动物的祖先细胞随着年龄增长会逐渐失去其分裂和生成新细胞的能力？Norman Sharpless及其同事培育出一种剔出了肿瘤抑制因子p16 INK4a的小鼠，该因子是细胞周期控制中涉及的一种蛋白，已知会以一种依赖于年龄的方式表达。在对该蛋白在血液、胰腺和大脑的再生中所起作用进行的研究中，三个小组分别发现，p16 INK4a不仅是一种生物标记，而且是衰老过程的一个促成因子。通过比较p16 INK4a在小鼠体内表达增多或减少所产生的效应，他们发现，p16 INK4a阻止干细胞的增殖，但只是在比较老的小鼠体内。综合起来，该研究表明，p16 INK4a通过肿瘤抑制因子的行动减少癌症的发病，与此同时通过降低干细胞功能对衰老做出贡献。该研究还表明，2-型糖尿病也许与胰岛失去再生能力有关，阻断该蛋白在某些组织中的作用，也许能够抵抗衰老的某些效应。
Page: 448
September 28, 2006
高质量恒星的质量怎样增长？
高质量或OB-型恒星能支配星系的出现和演化，并且肯定会合成重元素和通过高能风和超新星影响星际介质。但当前关于恒星形成的模型无法解释它们的存在。低质量恒星最初通过从周围物质中吸收气体来增长。但对一颗比太阳质量大10倍以上的恒星，强大的恒星辐射预计会抑制其吸收物质，并限制其质量的增长。现在，对朝向一个高质量恒星形成区域的一条氨线所做的观测，为认为高质量恒星通过非球状增长来形成的理论提供了支持：气体似乎是朝向一颗非常年轻的、约为太阳质量20倍的恒星内降落来帮助其增长的。
Page: 427
September 28, 2006
流体并非不可压缩
多年来成功用来描述气流和液流的标准流体动力学理论有一大假设：流体是注定不能压缩的。过去人们认为，对大多数体系，在流速接近声速之前，这个假设是成立的。但现在，研究表明，如果将粘度对密度的依赖考虑进去的话，即便对简单的剪切流，不可压缩的条件也会被违反。这些结果也许会为了解与低雷诺数下液体机械不稳定性相关的各种不同现象提供线索，包括在如金属气体和地幔等非常粘的液体中所看到的剪切带效应。
Page: 434
September 28, 2006
大气中甲烷水平变化的原因
过去20年里大气甲烷水平的变化有很好的记录，但这些变化的原因仍然不确定。Bousquet等人采用倒转的（即从上到下的）模拟方法来对1983和2004年间不同来源的甲烷排放所发生的变化进行量化。他们发现，上个世纪90年代大气甲烷增长速度的下降是由人为因素造成的排放的下降引起的，但人为因素造成的排放1999年以来又再次增加了。迄今，这种趋势一直被湿地排放的巧合降低所掩盖，但它有可能引起不远的将来甲烷总量再次增加。
Page: 439
September 28, 2006
油菜类固醇和茁长素之间的相互作用
油菜类固醇和茁长素是植物生长的重要调控因子，这两个通道经常调控同样基因的事实表明，它们之间一定有某种相互作用。而它们到底是怎样相互作用的却仍然是个谜，但新的证据表明，它们是在相当早的时候就有相互作用，甚至在胚根生长的最初阶段，它们就通过一个反馈环进行交流，这个反馈环以一种依赖于茁长素的方式维持油菜类固醇的水平。反过来，油菜类固醇会限制由茁长素诱导产生的转录响应的速度。对油菜类固醇水平敏感的拟南芥基因数量要比以前所认为的多很多，已知调控根部细胞增殖和伸长的BREVIS RADIX基因，被发现在油菜类固醇/茁长素相互作用中是一个重要参与者。
Page: 458
September 28, 2006
亚马逊/圭亚那地盾地区的生物数据库
在亚马逊流域/圭亚那地盾地区从事研究工作的研究人员积累了大量生态学数据集。现在，这项研究工作已经被综合在一个数据库中，内容涵盖25万棵树，它所提供的信息能够明显帮助我们认识亚马逊生态系统的生物多样性及其在全球气候系统中的位置。整个亚马逊地区树木组成和功能中两个主导梯度很明显，反映了土壤肥沃程度的分布和旱季长度的差别。这些数据还表明，圭亚那地盾中豆类的主导地位是由于它们的种子质量大，所受到的干扰小，而不是由于它们的根部能够适应贫瘠的土壤。
Page: 444
September 28, 2006
细胞溶解酶颗粒真正的输送方式
细胞毒性T-淋巴细胞是免疫系统的一个重要部分，在免疫突触上通过释放分泌性溶酶体中的内容来杀死目标。人们一般假设（通过与黑素细胞进行比较），细胞溶解酶颗粒是通过短的、加号端朝前的微管从微管组织中心向肌动蛋白细胞骨架运动的，目的是到达免疫突触。但实际上不是这样。现在，细胞毒性T-淋巴细胞被发现独立于肌动蛋白或加号端微管马达，而是利用一种由中心体的运动控制的新机制来输送致命的细胞溶解酶颗粒。
Page: 462
September 28, 2006
ATP酶泵离子的工作方式
P-型ATP酶离子泵存在于几乎所有细胞膜中，推动离子逆其浓度梯度穿过细胞膜。结构研究在近年来取得巨大进展，现在我们对离子泵里面是什么样子已经知道了很多，但仍然不清楚它们是怎样在一侧收集离子而在另一侧释放它们。现在，通过利用海洋毒素palytoxin来解耦Na+、K+-ATP酶的泵离子转位通道的控制门，从而将该泵转变成一种阳离子通道，Nicolás Reyes 和 David Gadsby获得了关于离子泵作用方式的一个新观点。在细胞外侧，离子通道以一个又深、又宽的门廊的形式开始，这个门廊突然变窄，形成一个阳离子选择性过滤器，由酸性侧链组成。引人注目的是，将它们当中仅仅一个的负电荷逆转，就会将该通道从阳离子选择性通道变成阴离子选择性通道。
Page: 470
September 28, 2006
酵母细胞中的“沙漏”
在重要的亚微米尺度上来研究细胞结构的分析方法几乎没有。Alina Vrabioiu 和 Timothy Mitchison已经研究出一种新方法，并用它来解决关于正在分裂的酵母细胞中的“沙漏”特征的结构的一个长期存在的争论。刚性附着的GFP的偏振荧光显微镜观测结果，被用来确定septin细丝的组织和septin的动态。Septin是与细胞分裂密切相关的一种聚合GTP酶。研究人员观察到，这些细丝在活酵母中形成有序组合，并在胞质分裂(cytokinesis)前转动90°。
Page: 466
Contents
Editorials
Priorities in astronomy p371
US astronomers are being forced to revisit their widely admired system for ranking large projects.
doi:10.1038/443371a
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A German academy p371
In seeking to build a credible national academy from scratch, Germany faces a tough challenge.
doi:10.1038/443371b
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Reforms on drug safety p372
Critics of the US Food and Drug Administration have a valid point.
doi:10.1038/443372a
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Top of pageResearch Highlights
Research highlights p374
doi:10.1038/443374a
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Top of pageNews
Stem cells derived from 'dead' human embryo p376
IVF cast-offs could provide 'ethical' source of eggs.
Helen Pearson and Alison Abbott
doi:10.1038/443376a
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Superconductivity research is down but not out p376
Absolute zero: survey suggests no papers for field after 2015.
Katharine Sanderson
doi:10.1038/443376b
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Is US hurricane report being quashed? p378
Some NOAA scientists say political appointees blocked climate-change message.
Jim Giles
doi:10.1038/443378a
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Snapshot: Face facts p379
A blow for Mars conspiracy theorists.
Jenny Hogan
doi:10.1038/443379a
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Statistical flaw trips up study of bad stats p379
Experts disagree over reanalysis of original data.
Jim Giles
doi:10.1038/443379b
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Sidelines p380
doi:10.1038/443380a
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Bad Boys question received wisdom on HIV p380
Cleveland gang tackle relation of viral load to AIDS.
Erika Check
doi:10.1038/443380b
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Mouse brain map is complete p380
Gene expression database goes online
David Brill
doi:10.1038/443380c
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'Big science' protein project under fire p382
Critics question results as Protein 3000 winds down
David Cyranoski
doi:10.1038/443382a
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News in brief p383
doi:10.1038/443383a
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Correction p383
doi:10.1038/443383b
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Top of pageBusiness
Turbulent times p385
The bid by Airbus to challenge the Boeing 747's dominance of the market faces an aerodynamic obstacle. Ned Stafford reports.
Ned Stafford
doi:10.1038/443385a
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Top of pageNews Features
Decadal surveys: Wishing for the stars p386
US astronomers are renowned for getting together and choosing their projects as a group. But just as these tactics are catching on in other fields, some say the astronomy process is grinding to a halt. Geoff Brumfiel investigates.
doi:10.1038/443386a
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Hagia Sophia: Shaken, not stirred p390
Hagia Sophia has stood four-square in Istanbul for more than 1,500 years. Virginia Hughes finds out how this venerable building has resisted the area's numerous earthquakes.
doi:10.1038/443390a
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Science journalism: Fighting a reporting battle p392
Science journalists in the developing world face unique stumbling blocks, even as some of the biggest science stories unfold around them. Mike Shanahan reports.
doi:10.1038/443392a
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Top of pageCorrespondence
Hungary's 'reforms' are threatening basic science p394
Zsuzsanna Izsvák, Zoltán Ivics and Lajos Mátés
doi:10.1038/443394a
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Challenge of choosing right level of microarray detail p394
Ron Edgar
doi:10.1038/443394b
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Funders with money to spare could just pay more p394
Shantenu Jha
doi:10.1038/443394c
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Piltdown wasn't cricket but does the hobbit ring true? p394
Simon L. Goodman
doi:10.1038/443394d
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Top of pageBooks and Arts
The making of the modern world p395
The end of the Second World War heralded a revolution in the use of technology in the West.
Nasir Tyabji reviews Transforming the Twentieth Century: Technical Innovations and their Consequences by Vaclav Smil
doi:10.1038/443395a
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Science uncut p396
Lee M. Silver reviews Sex, Drugs and DNA: Science's Taboos Confronted by Michael Stebbins
doi:10.1038/443396a
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Border crossings p397
doi:10.1038/443397a
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The moral element p397
Prashanth Ak reviews Against Bioethics by Jonathan Baron
doi:10.1038/443397b
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In Retrospect: Intellect and intuition p398
Gautam R Desiraju reviews An Idealist View of Life by Sarvepalli Radhakrishnan
doi:10.1038/443398a
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Top of pageNews and Views
Ecology: A pitcher of things to come p399
Big conclusions can be drawn from the tiny ecosystems that flourish in carnivorous pitcher plants. Manipulating habitat size and predator abundance reveals which is more important to ecosystem dynamics.
Jonathan B Shurin
doi:10.1038/443399a
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Chemistry: Hydrogen at the flick of a switch p400
Before hydrogen can be used as a transportation fuel, a safe storage system for the gas must be found. Metal clusters that release hydrogen in response to an electric current may be a step in the right direction.
Masanori Takimoto and Zhaomin Hou
doi:10.1038/443400a
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Evolution: Different paths to the same end p401
Genetic dissection of a yeast gene-regulatory pathway shows that the logical output of such a pathway can remain the same even though the molecular mechanisms underlying the output have diverged remarkably.
Antonis Rokas
doi:10.1038/443401a
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Condensed-matter physics: Coherent questions p403
Bose–Einstein condensation occurs when many particles enter into the same, coherent quantum state, and is now claimed to occur in various systems of 'quasiparticles' in solids. But is it the right term to use here?
David Snoke
doi:10.1038/443403a
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Ageing: Balancing regeneration and cancer p404
The proliferation of cells must balance the longevity assured by tissue renewal against the risk of developing cancer. The tumour-suppressor protein p16INK4a seems to act at the pivot of this delicate equilibrium.
Christian M Beausejour and Judith Campisi
doi:10.1038/nature05221
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Climate change: A nasty surprise in the greenhouse p405
The Kyoto Protocol aims to reduce emissions of greenhouse gases such as methane. But it seems that the fall in human-induced methane emissions in the 1990s was only transitory, and atmospheric methane might rise again.
Jos Lelieveld
doi:10.1038/443405a
Full Text | PDF (400K)
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Top of pageBrief Communications
Biomaterials: Silk-like secretion from tarantula feet p407
Stanislav N Gorb, Senta Niederegger, Cheryl Y Hayashi, Adam P Summers, Walter Vötsch and Paul Walther
doi:10.1038/443407a
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Top of pageBrief Communications Arising
Plant genetics: Increased outcrossing in hothead mutants pE8
Peng Peng, Simon W.-L. Chan, Govind A. Shah and Steve E. Jacobsen
doi:10.1038/nature05251
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Increased outcrossing in hothead mutants (Reply) pE8
Susan J. Lolle, Robert E. Pruitt, J. L. Victor and J. M. Young
doi:10.1038/nature05252
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Top of pageArticles
Bose–Einstein condensation of exciton polaritons p409
J. Kasprzak, M. Richard, S. Kundermann, A. Baas, P. Jeambrun, J. M. J. Keeling, F. M. Marchetti, M. H. Szymaska, R. André, J. L. Staehli, V. Savona, P. B. Littlewood, B. Deveaud and Le Si Dang
doi:10.1038/nature05131
Abstract | Full Text | PDF (2,573K) | Supplementary information
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Evolution of alternative transcriptional circuits with identical logic p415
Annie E. Tsong, Brian B. Tuch, Hao Li and Alexander D. Johnson
doi:10.1038/nature05099
Abstract | Full Text | PDF (2,099K) | Supplementary information
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Stem-cell ageing modified by the cyclin-dependent kinase inhibitor p16INK4a p421
Viktor Janzen, Randolf Forkert, Heather E. Fleming, Yoriko Saito, Michael T. Waring, David M. Dombkowski, Tao Cheng, Ronald A. DePinho, Norman E. Sharpless and David T. Scadden
doi:10.1038/nature05159
Abstract | Full Text | PDF (1,013K) | Supplementary information
See also: Editor's summary | News and Views by Beausejour & Campisi
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Top of pageLetters
Infall of gas as the formation mechanism of stars up to 20 times more massive than the Sun p427
Maria T. Beltrán, Riccardo Cesaroni, Claudio Codella, Leonardo Testi, Ray S. Furuya and Luca Olmi
doi:10.1038/nature05074
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Bose–Einstein condensation of quasi-equilibrium magnons at room temperature under pumping p430
S. O. Demokritov, V. E. Demidov, O. Dzyapko, G. A. Melkov, A. A. Serga, B. Hillebrands and A. N. Slavin
doi:10.1038/nature05117
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Violation of the incompressibility of liquid by simple shear flow p434
Akira Furukawa and Hajime Tanaka
doi:10.1038/nature05119
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Contribution of anthropogenic and natural sources to atmospheric methane variability p439
P. Bousquet, P. Ciais, J. B. Miller, E. J. Dlugokencky, D. A. Hauglustaine, C. Prigent, G. R. Van der Werf, P. Peylin, E.-G. Brunke, C. Carouge, R. L. Langenfelds, J. Lathière, F. Papa, M. Ramonet, M. Schmidt, L. P. Steele, S. C. Tyler and J. White
doi:10.1038/nature05132
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Continental-scale patterns of canopy tree composition and function across Amazonia p444
Hans ter Steege, Nigel C. A. Pitman, Oliver L. Phillips, Jerome Chave, Daniel Sabatier, Alvaro Duque, Jean-François Molino, Marie-Françoise Prévost, Rodolphe Spichiger, Hernán Castellanos, Patricio von Hildebrand and Rodolfo Vásquez
doi:10.1038/nature05134
First paragraph | Full Text | PDF (367K) | Supplementary information
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Increasing p16INK4a expression decreases forebrain progenitors and neurogenesis during ageing p448
Anna V. Molofsky, Shalom G. Slutsky, Nancy M. Joseph, Shenghui He, Ricardo Pardal, Janakiraman Krishnamurthy, Norman E. Sharpless and Sean J. Morrison
doi:10.1038/nature05091
First paragraph | Full Text | PDF (362K) | Supplementary information
See also: Editor's summary | News and Views by Beausejour & Campisi
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p16INK4a induces an age-dependent decline in islet regenerative potential p453
Janakiraman Krishnamurthy, Matthew R. Ramsey, Keith L. Ligon, Chad Torrice, Angela Koh, Susan Bonner-Weir and Norman E. Sharpless
doi:10.1038/nature05092
First paragraph | Full Text | PDF (438K) | Supplementary information
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BRX mediates feedback between brassinosteroid levels and auxin signalling in root growth p458
Céline F. Mouchel, Karen S. Osmont and Christian S. Hardtke
doi:10.1038/nature05130
First paragraph | Full Text | PDF (655K) | Supplementary information
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Centrosome polarization delivers secretory granules to the immunological synapse p462
Jane C. Stinchcombe, Endre Majorovits, Giovanna Bossi, Stephen Fuller and Gillian M. Griffiths
doi:10.1038/nature05071
First paragraph | Full Text | PDF (424K) | Supplementary information
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Structural insights into yeast septin organization from polarized fluorescence microscopy p466
Alina M. Vrabioiu and Timothy J. Mitchison
doi:10.1038/nature05109
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Ion permeation through the Na+,K+-ATPase p470
Nicolás Reyes and David C. Gadsby
doi:10.1038/nature05129
First paragraph | Full Text | PDF (2,142K) | Supplementary information
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Top of pageNaturejobs
Prospect
Prospects p475
Paul Smaglik
doi:10.1038/nj7110-475a
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Special Report
Building a better foundation p476
Europeans have traditionally expected their governments to fund research. But foundations are hoping to play a major new role, says Gene Russo.
Gene Russo
doi:10.1038/nj7110-476a
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Career Views
Haifan Lin, director, stem-cell programme, Yale University, New Haven, Connecticut p478
Virginia Gewin
doi:10.1038/nj7110-478a
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Investing in people p478
Sohaila Rastan
doi:10.1038/nj7110-478b
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Sounds of scientists p478
Milan de Vries
doi:10.1038/nj7110-478c
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Top of pageFutures
Twenty2 p480
The city without secrets.
Nate Balding
doi:10.1038/443480a
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