Volume 440 Number 7082 pp255-382 封面故事：构建DNA纳米结构的新方法
DNA是纳米结构的一个流行的构造单元，因为它既能自组装，又具有可编程性，而且还有大量化学方法可用来对其进行操纵。关于DNA纳米材料的制造问题已有大量文献，但本期Nature上描述的一个新方法却打破了很多常规。不可思议的是，虽然该方法忽略了序列设计、链的纯净度和链的集中比例，但它却能使所构建的DNA纳米结构比以前任何时候所构建的都更大、更复杂。这种从下往上“一锅烩”的方法用几百个短的DNA链来将一个非常长的链像订书针那样钉成二维结构，就像本期封面所示的那样，可以做成任何想要的形状，如方形、“纳米脸形”和五角星形。各个“订书针”也可以进行改造，将其做成纳米尺度的像素，后者可用来在一个100纳米的给定形状上生成表面图案。
人类第12号染色体的分析结果
Nature曾发表了关于已完成测序的人类染色体的系列论文，本期又发表了人类第12号染色体的分析结果。该染色体占人类基因组的4.5%，其上有若干在特定类型的癌症、运动失调症、以及还可能包括“阿尔茨海默氏症”在内的疾病中发生突变的基因。
可用作抗沙门氏菌药物作用目标的13种酶
在一项设计用来显示抗菌素可能作用目标的实验中，研究人员将突变体表现型分析、蛋白质组合基因组对比等方法结合起来，来确定在小鼠患伤寒和肠胃炎期间沙门氏菌的代谢网络。由于存在很多多余的通道，沙门氏菌的代谢之旺盛让人吃惊，而且只发现126种酶是沙门氏菌的致病作用所必需的。当然，其中有13种是很有希望的、未被利用的药物作用目标。以这些目标为重点，也许可加快对沙门氏菌有活性的急需的抗生素的开发。
褐矮星质量和半径的直接测量
褐矮星是所谓的“失败的恒星”，它们没有足够的质量来维持核反应，但质量又太大而无法成为行星。由于处在这种“夹在中间的位置”，褐矮星能为我们了解恒星和行星的性质及起源提供独特的线索。此前，一直不可能直接测量褐矮星的基本物理性质。但现在，由于在“猎户座”星云恒星形成区域一个正在发生星蚀的双星体系中发现了两颗年轻的褐矮星，天文学家就有可能同时对两颗褐矮星的质量和半径进行测量了。令人吃惊的是，质量较小的一颗褐矮星是两者中更热的一颗，这是一个与关于同时期褐矮星的所有当前理论模型的预测结果都相反的发现。这也许意味着，两颗褐矮星不是同时形成的，而是在不久前才聚到一起的。
银河系中心附近的双螺旋结构
由“斯皮策太空望远镜”获得的红外图像显示，在我们银河系中心附近有一个形状，生物学家比天文学家更熟悉它，这个形状就是一个双螺旋。该双螺旋星云垂直于银河系平面，与银河系中心相距约100秒差距。对该结构的一个初步解释是，它代表一个扭转的Alfvén波，从银河系圆盘面向外传播，其传播的动力来自一个由磁化的气体构成的转动的云团。
三体量子态的实验演示
在量子物理的奇异世界中，三种相互作用的粒子能形成一个松散约束的体系，即便二粒子引力太弱、不允许结合成一个粒子对。这种奇异的三聚状态是在35年前由俄罗斯物理学家Vitali Efimov预测的，他为解决极为困难的量子力学三体问题找到了一个引人注目的、违反直觉的方法。Efimov著名的结果在理论“少体”（few-body）物理学中是一个里程碑式的结果，但此前这些奇异的量子态一直未能通过实验来演示。现在，研究人员在一个由铯原子构成的超冷气体中做到了这一点。该气体的存在证实了一些关键的预测，使少体量子体系为进一步实验研究敞开了大门。
能用超声波交流的青蛙
有些蝙蝠、海豚和啮齿类动物因能够产生和探测超声频率，而使它们显得与其他脊椎动物有所不同。现在，一种两栖动物也首次得以能够加入这个行列。过去，据说由一种青蛙发出的类似鸟叫的壮观的声音也属于超声的范畴。现在，研究人员发现这些青蛙把超声波用作一种交流形式。至少雄性在竞争领地的过程中是这样做的。从演化上来说，青蛙与使用超声波的其他已知动物相差很远，所以这种本领似乎是分几次独立演化形成的。也可能是很多其他物种也在用超声波进行交流，只是没有人注意到它们而已。
德国南部新发现一兽脚类恐龙化石
晚侏罗纪的小型食肉恐龙在世界范围内都很少见，在欧洲只发现了名为Compsognathus的两个保存状况很差的骨架化石。Chiappe 和 Goelich描述了一种以前未知的兽脚亚目的恐龙，同Compsognathus和大多数始祖鸟一样，也是来自德国南部Solnhofen的晚侏罗纪地层。 新发现的化石同始祖鸟保存得一样完好，但令人吃惊的是，它绝对没有羽毛状皮肤覆盖物的任何迹象，这说明在恐龙类动物中羽毛演化的历史要比以前所认为的更为复杂。
“阿尔茨海默氏症”的早期信号
在患“阿尔茨海默氏症”近15年后才被诊断出来的患者身上，研究人员注意到了记忆力减退的迹象。现在，用“阿尔茨海默氏症”的一种小鼠模型所做的实验，追踪到了这种早期信号的一个可能的原因，即一种可溶性淀粉质贝塔-肽聚合物在细胞外的积累。当将该物质从患类似于“阿尔茨海默氏症”的疾病的小鼠身上分离出来、随后注射进大鼠体内时，大鼠也表现出短暂的记忆力减退，而这种记忆力减退与斑块形成或神经元损失（“阿尔茨海默氏症”的典型特征）无关。这项工作表明该物质是一个潜在的诊断目标，同时也提出这样一个可能性：如果能够足够早地针对这个目标采取措施，也许能够防止或延迟该疾病后期典型的永久性结构变化的出现。
在单分子层次上对基因表达的直接观测
分子生物学上一个中心假设是，细胞通过将DNA转录成信使RNA来发挥作用，后者然后又被翻译成蛋白质。这个假设我们都非常熟悉，而且也没有争议。但基因表达一直没有在一个活细胞中、在单个分子基础上被直接实时观测到。现在，研究人员开发出一个活细胞分析体系，它使得这种单分子直接观测成为可能，并且可以显示基因表达在活细胞中是怎样进行的。在大肠杆菌、酵母和小鼠胚胎干细胞中试验过的这个分析体系表明，蛋白分子是脉冲式产生的，每个脉冲中分子的分布可以被测定出来，以指示基因表达水平，后者可在不同条件下进行比较。这一成果有可能将基因表达分析工作的灵敏度提高到远远超过当前方法所能达到的水平。
萤火虫的荧光颜色变化的诱因
萤火虫利用彩色光进行交流，这种彩色光是当一种被电子激发的氧化荧光素（由荧光素酶产生）恢复到其基态时发射出来的。这种酶的点突变能大大改变这一生物光的颜色，而且尽管荧光素酶的X-射线晶体结构以前已经获得，但这种颜色变化的精确性质却一直让生物学家们捉摸不透。现在，Nakatsu等人解决了处于几种不同状态的荧光素酶的X-射线晶体结构，并且发现一种异亮氨酸残体中的一个特定构象变化是生物光颜色变化的诱发因素。
ContentsEditorials
Going by the book p255
In Italy's election campaign, opposition parties have pledged research reform — but nothing will change until agency chiefs start playing by the rules.
doi:10.1038/440255a
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Dreams of flu data p255
The lack of an accessible store of information is undermining the fight against avian flu.
doi:10.1038/440255b
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The right chemistry p256
Nature celebrates a discipline's unheralded achievements.
doi:10.1038/440256a
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Top of pageResearch Highlights
Research highlights p258
doi:10.1038/440258a
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Top of pageNews
Comet chasers get mineral shock p260
Stardust mission yields unexpected bounty.
Mark Peplow
doi:10.1038/440260a
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Signs of warm water on Saturn's moon p261
Cassini probe reveals conditions that might support life on Enceladus.
Mark Peplow
doi:10.1038/440261a
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Sidelines p262
doi:10.1038/440262a
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Consumer products leap aboard the nano bandwagon p262
Number of products boasting small science doubles.
Geoff Brumfiel
doi:10.1038/440262b
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Huge Biobank project launches despite critics p263
Half a million British subjects to be monitored in sickness and in health.
Jim Giles
doi:10.1038/440263a
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Saving Italian science p264
As the general election looms, candidate prime minister Romano Prodi strives to convince Italy's discontented scientists that he can turn things around. Alison Abbott reports.
Alison Abbott
doi:10.1038/440264a
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News in brief p267
doi:10.1038/440267a
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Top of pageNews Features
Particle physics: Let the games begin p268
A series of mental challenges is helping physicists to prepare for the strange data they may get when the next particle accelerator goes live. Jenny Hogan joins the work-out.
doi:10.1038/440268a
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Drug trials: Stacking the deck p270
Studies of medical literature are confirming what many suspected — reporters of clinical trials do not always play straight. Jim Giles talks to those pushing for a fairer deal.
doi:10.1038/440270a
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Political chemistry: Make a strong bond p274
Alison Abbott talks to the man who wants theoretical chemistry to ease political strife in the Middle East.
doi:10.1038/440274a
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Top of pageBusiness
Make or break time in Vioxx drama p277
Cases involving long-term users of Vioxx will, as Meredith Wadman reports, determine the true cost to Merck and the drug industry of the painkiller's withdrawal.
doi:10.1038/440277a
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Top of pageCorrespondence
Wiki ware could harness the Internet for science p278
Kevin Yager
doi:10.1038/440278a
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Lyme vaccine demonized by advocacy groups p278
Edward McSweegan
doi:10.1038/440278b
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Lyme vaccine: studies have raised genuine concerns p278
Carl Brenner
doi:10.1038/440278c
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Reprocessing method could allay weapons fear p278
Gerald E. Marsh and George S. Stanford
doi:10.1038/440278d
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Top of pageBooks and Arts
The world at your fingertips p279
The rise of the Internet search engine Google as guardian, gate-keeper and guide to a wealth of information.
Jon Kleinberg reviews The Search: How Google and its Rivals Rewrote the Rules of Business and Transformed Our Culture by John Battelle and The Google Story: Inside the Hottest Business, Media and Technology Success of Our Time by David Vise and Mark Malseed
doi:10.1038/440279a
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The bright side of life p280
Thomas G. Oertner reviews Aglow in the Dark: The Revolutionary Science of Biofluorescence by Vincent Pieribone and David F. Gruber
doi:10.1038/440280a
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Journey to the end of the Earth p281
Lloyd Peck reviews Terra Antarctica: Looking Into the Emptiest Continent by William L. Fox
doi:10.1038/440281a
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Top of pageNews and Views
Nanostructures: The manifold faces of DNA p283
When it comes to making shapes out of DNA, the material is there, and its properties are understood. What was missing was a convincing, universal design scheme to allow our capabilities to unfold to the full.
Lloyd M. Smith
doi:10.1038/440283a
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Alzheimer's disease: A needle from the haystack p284
Abnormal protein clumps of many varieties build up in the brains of individuals with Alzheimer's disease. But which types actually cause memory deficits? The behaviour of model mice might help to find out.
Richard Morris and Lennart Mucke
doi:10.1038/440284a
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Chemical biology: A pocketful of colour p285
Joshua Finkelstein
doi:10.1038/440285a
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50 & 100 years ago p286
doi:10.1038/440286a
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Photochemistry: Lighting up nanomachines p286
A cleverly engineered molecule uses light to generate a charge-separated state and so cause one of its components to move. It's the latest study of a molecular machine that exploits nature's most plentiful energy source.
Euan R. Kay and David A. Leigh
doi:10.1038/440286b
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Palaeontology: Scales, feathers and dinosaurs p287
A fossil dinosaur that 'nests' with feathered relations in the dinosaur phylogenetic tree did not, it seems, have feathers. The discovery will encourage a re-evaluation of feather evolution.
Xing Xu
doi:10.1038/440287a
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Analytical chemistry: Forever blowing bubbles p289
Magdalena Helmer
doi:10.1038/440289a
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Quantum physics: A ménage à trois laid bare p289
Quantum bodies that can't settle down together in pairs get on fine in a cosy threesome. This startling claim about the private life of particles has just seen its first experimental confirmation.
Brett D. Esry and Chris H. Greene
doi:10.1038/440289b
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Obituary: Pierre Potier (1934–2006) p291
Pharmacist and natural-products chemist, who devised widely used treatments for cancer.
François Chast
doi:10.1038/440291a
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Top of pageNews and Views Feature
Dinosaur Locomotion: Beyond the bones p292
How did dinosaurs stand and move? Computer simulation and other methods have told us much about how dinosaurs did and did not move, but they have not yet reached their full potential.
John R. Hutchinson and Stephen M. Gatesy
doi:10.1038/440292a
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Top of pageBrief Communications
Photocatalyst releasing hydrogen from water p295
Enhancing catalytic performance holds promise for hydrogen production by water splitting in sunlight.
Kazuhiko Maeda, Kentaro Teramura, Daling Lu, Tsuyoshi Takata, Nobuo Saito, Yasunobu Inoue and Kazunari Domen
doi:10.1038/440295a
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Top of pageBrief Communications Arising
Geophysics: Hot fluids or rock in eclogite metamorphism? pE4
M. G. Bjørnerud and H. Austrheim
doi:10.1038/nature04714
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Geophysics: Hot fluids or rock in eclogite metamorphism? (Reply) pE4
Alfredo Camacho, James K. W, Bastiaan-J. Hensen and Jean Braun
doi:10.1038/nature04715
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Top of pageArticles
Folding DNA to create nanoscale shapes and patterns p297
Paul W. K. Rothemund
doi:10.1038/nature04586
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Robust Salmonella metabolism limits possibilities for new antimicrobials p303
Daniel Becker, Matthias Selbach, Claudia Rollenhagen, Matthias Ballmaier, Thomas F. Meyer, Matthias Mann and Dirk Bumann
doi:10.1038/nature04616
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Top of pageLetters
A magnetic torsional wave near the Galactic Centre traced by a 'double helix' nebula p308
Mark Morris, Keven Uchida and Tuan Do
doi:10.1038/nature04554
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Discovery of two young brown dwarfs in an eclipsing binary system p311
Keivan G. Stassun, Robert D. Mathieu and Jeff A. Valenti
doi:10.1038/nature04570
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Evidence for Efimov quantum states in an ultracold gas of caesium atoms p315
T. Kraemer, M. Mark, P. Waldburger, J. G. Danzl, C. Chin, B. Engeser, A. D. Lange, K. Pilch, A. Jaakkola, H.-C. Nägerl and R. Grimm
doi:10.1038/nature04626
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Visualizing dislocation nucleation by indenting colloidal crystals p319
Peter Schall, Itai Cohen, David A. Weitz and Frans Spaepen
doi:10.1038/nature04557
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A mechanism to thin the continental lithosphere at magma-poor margins p324
Luc L. Lavier and Gianreto Manatschal
doi:10.1038/nature04608
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A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago p329
Ursula B. Göhlich and Luis M. Chiappe
doi:10.1038/nature04579
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Ultrasonic communication in frogs p333
Albert S. Feng, Peter M. Narins, Chun-He Xu, Wen-Yu Lin, Zu-Lin Yu, Qiang Qiu, Zhi-Min Xu and Jun-Xian Shen
doi:10.1038/nature04416
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Prioritizing global conservation efforts p337
Kerrie A. Wilson, Marissa F. McBride, Michael Bode and Hugh P. Possingham
doi:10.1038/nature04366
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Multiple rounds of speciation associated with reciprocal gene loss in polyploid yeasts p341
Devin R. Scannell, Kevin P. Byrne, Jonathan L. Gordon, Simon Wong and Kenneth H. Wolfe
doi:10.1038/nature04562
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The finished DNA sequence of human chromosome 12 p346
Steven E. Scherer, Donna M. Muzny, Christian J. Buhay, Rui Chen, Andrew Cree, Yan Ding, Shannon Dugan-Rocha, Rachel Gill, Preethi Gunaratne, R. Alan Harris, Alicia C. Hawes, Judith Hernandez, Anne V. Hodgson, Jennifer Hume, Andrew Jackson, Ziad Mohid Khan, Christie Kovar-Smith, Lora R. Lewis, Ryan J. Lozado, Michael L. Metzker, Aleksandar Milosavljevic, George R. Miner, Kate T. Montgomery, Margaret B. Morgan, Lynne V. Nazareth, Graham Scott, Erica Sodergren, Xing-Zhi Song, David Steffen, Ruth C. Lovering, David A. Wheeler, Kim C. Worley, Yi Yuan, Zhengdong Zhang, Charles Q. Adams, M. Ali Ansari-Lari, Mulu Ayele, Mary J. Brown, Guan Chen, Zhijian Chen, Kerstin P. Clerc-Blankenburg, Clay Davis, Oliver Delgado, Huyen H. Dinh, Heather Draper, Manuel L. Gonzalez-Garay, Paul Havlak, Laronda R. Jackson, Leni S. Jacob, Susan H. Kelly, Li Li, Zhangwan Li, Jing Liu, Wen Liu, Jing Lu, Manjula Maheshwari, Bao-Viet Nguyen, Geoffrey O. Okwuonu, Shiran Pasternak, Lesette M. Perez, Farah J. H. Plopper, Jireh Santibanez, Hua Shen, Paul E. Tabor, Daniel Verduzco, Lenee Waldron, Qiaoyan Wang, Gabrielle A. Williams, JingKun Zhang, Jianling Zhou, The Baylor College of Medicine Human Genome Sequencing Center Sequence Production Team, David Nelson, Raju Kucherlapati, George Weinstock and Richard A. Gibbs
doi:10.1038/nature04569
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A specific amyloid- protein assembly in the brain impairs memory p352
Sylvain Lesné, Ming Teng Koh, Linda Kotilinek, Rakez Kayed, Charles G. Glabe, Austin Yang, Michela Gallagher and Karen H. Ashe
doi:10.1038/nature04533
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Stochastic protein expression in individual cells at the single molecule level p358
Long Cai, Nir Friedman and X. Sunney Xie
doi:10.1038/nature04599
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The PerR transcription factor senses H2O2 by metal-catalysed histidine oxidation p363
Jin-Won Lee and John D. Helmann
doi:10.1038/nature04537
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Crystal structure of the non-haem iron halogenase SyrB2 in syringomycin biosynthesis p368
Leah C. Blasiak, Frédéric H. Vaillancourt, Christopher T. Walsh and Catherine L. Drennan
doi:10.1038/nature04544
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Structural basis for the spectral difference in luciferase bioluminescence p372
Toru Nakatsu, Susumu Ichiyama, Jun Hiratake, Adrian Saldanha, Nobuyuki Kobashi, Kanzo Sakata and Hiroaki Kato
doi:10.1038/nature04542
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Top of pageNaturejobs
Prospect
Bench partners p377
Technicians' roles deserve a closer look.
Paul Smaglik
doi:10.1038/nj7082-377a
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Special Report
Chemistry's evolution p378
Industry's need to reduce waste and deal with the environmental concerns of consumers is creating demand for cleaner catalysis, says Virginia Gewin.
Virginia Gewin
doi:10.1038/nj7082-378a
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Career Views
Andrew Chien, director of research and vice-president of corporate technology group Intel, based in Hillsboro, Oregon p380
Academic computer scientist moves to Intel.
Virginia Gewin
doi:10.1038/nj7082-380a
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What's holding you back p380
Beating those psychological barriers.
Michael Alvarez
doi:10.1038/nj7082-380b
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Graduate Journal: Master of multitasking p380
Have you got grad skills?
Milan de Vries
doi:10.1038/nj7082-380c
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Top of pageFutures
Product development p382
Switch off, tune out, and clean up.
Nancy Kress
doi:10.1038/440382a
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