Table of contents
Volume 423 Number 6938 pp367-464
Editorials
Brazil's R&D agenda p367
The new Brazilian president has so far impressed with his handling of the country's shaky economy. He should now seize an opportunity to transform Brazil's ability to use science and technology for its economic development.
doi:10.1038/423367a
Trade war: what is it good for? p367
The United States' challenge to Europe's ban on approving new transgenic foods could yield nothing but losers.
doi:10.1038/423367b
News
Trade war looms as US launches challenge over transgenic crops p369
Jonathan Knight
doi:10.1038/423369a
Iraqi looters spark alert over radiation risks p370
Geoff Brumfiel
doi:10.1038/423370a
Animal studies hint at staying power of SARS p370
Helen Pearson
doi:10.1038/423370b
Lack of trust hampers hunt for weapons p371
Declan Butler
doi:10.1038/423371a
Brazilian brain experts plan research village p372
Hannah Hoag
doi:10.1038/423372a
Spiralling costs dog comet mission p372
Declan Butler
doi:10.1038/423372b
Copied citations give impact factors a boost p373
Tom Clarke
doi:10.1038/423373a
Researchers divided over ethics of a ban on cloning p373
Alison Abbott
doi:10.1038/423373b
news feature
Correction p374
doi:10.1038/423374b
Scientific literacy: Clear as mud p376
It's not surprising that some academic papers seem to swim before our eyes — the scientific literature has become steadily less accessible over the past half-century. Can we stop this trend, asks Jonathan Knight.
Jonathan Knight
doi:10.1038/423376a
Brazilian science: Under new management p379
After decades of rule by first the military and then parties associated with the privileged élite, Brazil now has a left-wing president. David Adam considers the implications for the country's science.
David Adam
doi:10.1038/423379a
Correspondence
Embryos aren't essential to stem-cell research p381
James L. Sherley
doi:10.1038/423381a
Politics hindering SARS work p381
Taiwan has been left to fight its outbreak with little help.
Ying-Hen Hsieh
doi:10.1038/423381b
US federal funding ban puts babies at risk p381
Sandra Carson and Robert Brzyski
doi:10.1038/423381c
Books and Arts
Making your mind up p383
Neurons with sustained activity could help us to understand cognition.
Kevan Martin reviews Cortex and Mind: Unifying Cognition by Joaquín M. Fuster
doi:10.1038/423383a
Suffocated or shot? p384
Peter J. Bowler reviews When Life Nearly Died: The Greatest Mass Extinction of All Time by Michael Benton
doi:10.1038/423384a
Hooke, life and thinker p384
David R. Oldroyd reviews London's Leonardo: The Life and Work of Robert Hooke by Jim Bennett, Michael Cooper, Michael Hunter and Lisa Jardine
doi:10.1038/423384b
Art: Science in site p385
Alison Abbott
doi:10.1038/423385a
News and Views
Vision: The retina's fancy tricks p387
The vertebrate eye is far more than a passive receptor for visual information. The microcircuitry in the retina can, for instance, carry out the job of distinguishing object motion from background motion.
Richard H. Masland
doi:10.1038/423387a
Astronomy: New direction for 
-rays p388
The origin of energetic 
-ray bursts is still unknown. But the detection of polarization of the -rays provides fresh insight into the mechanism driving these powerful explosions.
Eli Waxman
doi:10.1038/423388a
100 and 50 years ago p389
doi:10.1038/423389a
Gene expression: Silent clones speak up p390
An important category of genes — so-called pluripotency genes — are active in early embryos but silent in specialized cells. It seems that this silencing is difficult to reverse in cloned embryos.
Wolf Reik and Wendy Dean
doi:10.1038/423390a
RNA interference: Cereal adultery p390
Christopher Surridge
doi:10.1038/423390b
Condensed-matter physics: Thermopower to the people p391
The larger-than-expected thermally generated voltage seen in a layered-oxide material — which may prove useful in power generation or cooling — is now attributed to the spins of moving charges.
Cronin B. Vining
doi:10.1038/423391a
Alzheimer's disease: Mental plaque removal p392
Lithium, already used to treat psychiatric disorders, has been found to reduce amyloid-peptide production in a mouse model of Alzheimer's disease. The implication is that lithium's target molecule helps to generate the peptides.
Bart De Strooper and James Woodgett
doi:10.1038/423392a
Synthetic chemistry: A perfect fit p394
Two molecules may form a dimer if lured into an organic 'nanocage'. So far, the approach has only worked for identical molecules. But two different molecules will dimerize if, together, they snugly fit the dimensions of the cage.
V. Ramamurthy
doi:10.1038/423394a
news and views in brief p395
doi:10.1038/423395a
Brief Communications
Mammalian microevolution: Rapid change in mouse mitochondrial DNA p397
Wild mice around Chicago may have switched genotype to keep pace with modern living.
Oliver R.W. Pergams, Wayne M. Barnes and Dennis Nyberg
doi:10.1038/423397a
First paragraph | Full Text | PDF (197K) | Supplementary information
High-temperature superconductors: Universal nodal Fermi velocity p398
X. J. Zhou, T. Yoshida, A. Lanzara, P. V. Bogdanov, S. A. Kellar, K. M. Shen, W. L. Yang, F. Ronning, T. Sasagawa, T. Kakeshita, T. Noda, H. Eisaki, S. Uchida, C. T. Lin, F. Zhou, J. W. Xiong, W. X. Ti, Z. X. Zhao, A. Fujimori, Z. Hussain and Z.-X. Shen
doi:10.1038/423398a
First paragraph | Full Text | PDF (193K) | Supplementary information
Marine ecology: Spring algal bloom and larval fish survival p398
Trevor Platt, Csar Fuentes-Yaco and Kenneth T. Frank
doi:10.1038/423398b
First paragraph | Full Text | PDF (193K)
Ecology: Hunting and fox numbers in the United Kingdom p400
Nicholas J. Aebischer, Sandra E. Baker, Paul J. Johnson, David W. Macdonald and Jonathan C. Reynolds
doi:10.1038/423400a
First paragraph | Full Text | PDF (98K)
Ecology: Hunting and fox numbers in the United Kingdom p400
Philip J. Baker, Stephen Harris and Charlotte C. Webbon
doi:10.1038/423400b
correction: Deepwater variability in the Holocene epoch p400
doi:10.1038/423400c
Articles
Segregation of object and background motion in the retina p401
Bence P. Ölveczky, Stephen A. Baccus and Markus Meister
doi:10.1038/nature01652
Abstract | Full Text | PDF (625K) | Supplementary information
See also: News and Views by Masland
A role for Wnt signalling in self-renewal of haematopoietic stem cells p409
Tannishtha Reya, Andrew W. Duncan, Laurie Ailles, Jos Domen, David C. Scherer, Karl Willert, Lindsay Hintz, Roel Nusse and Irving L. Weissman
doi:10.1038/nature01593
Abstract | Full Text | PDF (346K) | Supplementary information
Letters to Nature
Polarization of the prompt -ray emission from the -ray burst of 6 December 2002 p415
Wayne Coburn and Steven E. Boggs
doi:10.1038/nature01612
First paragraph | Full Text | PDF (182K)
See also: News and Views by Waxman
Experimental entanglement purification of arbitrary unknown states p417
Jian-Wei Pan, Sara Gasparoni, Rupert Ursin, Gregor Weihs and Anton Zeilinger
doi:10.1038/nature01623
First paragraph | Full Text | PDF (364K)
Real-time detection of electron tunnelling in a quantum dot p422
Wei Lu, Zhongqing Ji, Loren Pfeiffer, K. W. West and A. J. Rimberg
doi:10.1038/nature01642
First paragraph | Full Text | PDF (310K)
See also: News and Views by Vining
Spin entropy as the likely source of enhanced thermopower in NaxCo2O4 p425
Yayu Wang, Nyrissa S. Rogado, R. J. Cava and N. P. Ong
doi:10.1038/nature01639
First paragraph | Full Text | PDF (285K) | Supplementary information
146Sm–142Nd evidence from Isua metamorphosed sediments for early differentiation of the Earth's mantle p428
Guillaume Caro, Bernard Bourdon, Jean-Louis Birck and Stephen Moorbath
doi:10.1038/nature01668
First paragraph | Full Text | PDF (272K) | Supplementary information
Spontaneous emergence of leaders and followers in foraging pairs p432
Sean A. Rands, Guy Cowlishaw, Richard A. Pettifor, J. Marcus Rowcliffe and Rufus A. Johnstone
doi:10.1038/nature01630
First paragraph | Full Text | PDF (265K) | Supplementary information
GSK-3
regulates production of Alzheimer's disease amyloid-
peptides p435
Christopher J. Phiel, Christina A. Wilson, Virginia M.-Y. Lee and Peter S. Klein
doi:10.1038/nature01640
First paragraph | Full Text | PDF (344K)
See also: News and Views by De Strooper & Woodgett
Caenorhabditis elegans early embryogenesis and vulval morphogenesis require chondroitin biosynthesis p439
Ho-Yon Hwang, Sara K. Olson, Jeffrey D. Esko and H. Robert Horvitz
doi:10.1038/nature01634
First paragraph | Full Text | PDF (628K) | Supplementary information
Chondroitin proteoglycans are involved in cell division of Caenorhabditis elegans p443
Souhei Mizuguchi, Toru Uyama, Hiroshi Kitagawa, Kazuko H. Nomura, Katsufumi Dejima, Keiko Gengyo-Ando, Shohei Mitani, Kazuyuki Sugahara and Kazuya Nomura
doi:10.1038/nature01635
First paragraph | Full Text | PDF (2,078K) | Supplementary information
Wnt proteins are lipid-modified and can act as stem cell growth factors p448
Karl Willert, Jeffrey D. Brown, Esther Danenberg, Andrew W. Duncan, Irving L. Weissman, Tannishtha Reya, John R. Yates, III and Roel Nusse
doi:10.1038/nature01611
First paragraph | Full Text | PDF (412K) | Supplementary information
Deficiency of the adaptor SLP-65 in pre-B-cell acute lymphoblastic leukaemia p452
Hassan Jumaa, Lukas Bossaller, Karina Portugal, Bettina Storch, Michael Lotz, Alexandra Flemming, Martin Schrappe, Ville Postila, Pekka Riikonen, Jukka Pelkonen, Charlotte M. Niemeyer and Michael Reth
doi:10.1038/nature01608
First paragraph | Full Text | PDF (275K) | Supplementary information
Humanin peptide suppresses apoptosis by interfering with Bax activation p456
Bin Guo, Dayong Zhai, Edelmira Cabezas, Kate Welsh, Shahrzad Nouraini, Arnold C. Satterthwait and John C. Reed
doi:10.1038/nature01627
First paragraph | Full Text | PDF (407K) | Supplementary information
corrigendum: Fungus-growing ants use antibiotic-producing bacteria to control garden parasites p461
C. R. Currie, J. A. Scott, R. C. Summerbell and D. Malloch
doi:10.1038/nature01563
corrigendum: High brightness electron beam from a multi-walled carbon nanotube p461
Niels de Jonge, Yann Lamy, Koen Schoots and Tjerk H. Oosterkamp
doi:10.1038/nature01620
addendum: HIV-1 superinfection despite broad CD8+ T-cell responses containing replication of the primary virus p461
Marcus Altfeld, Todd M. Allen, Xu G. Yu, Mary N. Johnston, Deepak Agrawal, Bette T. Korber, David C. Montefiori, David H. O'Connor, Ben T. Davis, Paul K. Lee, Erica L. Maier, Jason Harlow, Philip J. R. Goulder, Christian Brander, Eric S. Rosenberg and Bruce D. Walker
doi:10.1038/nature01662
erratum: Subsecond dopamine release promotes cocaine seeking p461
Paul E. M. Phillips, Garret D. Stuber, Michael L. A. V. Heien, R. Mark Wightman and Regina M. Carelli
doi:10.1038/nature01664
New on the Market
Proteins pure and applied p462
Protein purification, scaled-up production and analysis.
doi:10.1038/423462a
Naturejobs
ProspectsCracking the combination p463
Paul Smaglik
doi:10.1038/nj6938-463a
movers
Movers p464
doi:10.1038/nj6938-464a