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Summaries of newsworthy papers include Magnetic power behind a gamma-ray burst, Red Queen revamped; Tetrahedra get close, Compositional effects on deep mantle discontinuity, Sharing childcare makes for yummy mummies

WWW.NATURE.COM/NATURE This press release is copyright Nature. VOL.462 NO.7274 DATED 10 DECEMBER 2009 This press release contains: · Summaries of newsworthy papers: Earth science: Flooding the Mediterranean Astronomy: Magnetic power behind a gamma-ray burst Evolution: Red Queen revamped Materials science: Tetrahedra get close Earth science: Compositional effects on deep mantle discontinuity And finally… Sharing childcare makes for yummy mummies · Mention of papers to be published at the same time with the same embargo · Geographical listing of authors Editorial contacts: While the best contacts for stories will always be the authors themselves, in some cases the Nature editor who handled the paper will be available for comment if an author is unobtainable. Editors are contactable via Ruth Francis on +44 20 7843 4562. Feel free to get in touch with Nature's press contacts in London, Washington and Tokyo (as listed at the end of this release) with any general editorial inquiry. 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The Nature journals press site is at http://press.nature.com · PDFs for the Articles, Letters, Progress articles, Review articles, Insights and Brief Communications in this issue will be available on the Nature journals press site from 1400 London time / 0900 US Eastern time on the Friday before publication. · PDFs of News & Views, News Features, Correspondence and Commentaries will be available from 1400 London time / 0900 US Eastern time on the Monday before publication PICTURES: While we are happy for images from Nature to be reproduced for the purposes of contemporaneous news reporting, you must also seek permission from the copyright holder (if named) or author of the research paper in question (if not). HYPE: We take great care not to hype the papers mentioned on our press releases, but are sometimes accused of doing so. If you ever consider that a story has been hyped, please do not hesitate to contact us at press@nature.com, citing the specific example. PLEASE CITE NATURE AND OUR WEBSITE www.nature.com/nature AS THE SOURCE OF THE FOLLOWING ITEMS. IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO http://www.nature.com/nature [1] Earth science: Flooding the Mediterranean (pp 778-781) The modern Mediterranean Sea was formed when a catastrophic flood breached the strait of Gibraltar about 5.3 million years ago, according to research published in Nature this week. The flood, which reconnected the Mediterranean with the Atlantic, may have involved peak rates of sea level rise of over 10 metres per day. The Mediterranean Sea became isolated from the world’s oceans about 5.6 million years ago, and is thought to have evaporated almost completely during a period known as the Messinian salinity crisis. Scientists believe that tectonic subsidence around Gibraltar may have eventually triggered a flood that refilled the Mediterranean basin, but the nature, abruptness and evolution of the flood remains poorly understood. Daniel García-Castellanos and colleagues use borehole and seismic data to reveal a 200-kilometre long channel across the Gibraltar strait, carved out by the floodwaters. Using an incision model to estimate the duration of the flood, they find that it began slowly with low discharges for up to several thousand years, but 90% of the water was then rapidly transferred in a period ranging from a few months to two years. Rather than a waterfall over the Gibraltar Strait as has been suggested in previous studies, the data suggest a huge ramp, several kilometres wide descending from the Atlantic to the Mediterranean. CONTACT Daniel García-Castellanos (Institut de Ciències de la Terra Jaume Almera, CSIC, Barcelona, Spain) Tel: +34 617506676; E-mail: danielgc@ictja.csic.es [2] Astronomy: Magnetic power behind a gamma-ray burst (pp 767-769; N&V) A clue to the power behind the most energetic explosions in the Universe is reported in this week’s Nature. Observations of polarized light coming from the gamma-ray burst GRB 090102 indicate the presence of large-scale magnetic fields originating in the central fireball, which may accelerate and collimate the expanding jets of gas. Most gamma-ray bursts are thought to arise from particularly energetic supernova explosions. The material ejected in the explosion is accelerated to velocities close to that of light, and these relativistic outflows seem to be concentrated into narrow jets. The gamma rays are also emitted in narrow beams, one of which needs to point towards the Earth for the burst to be observed. Beyond this general picture, there is no clear understanding of the physical mechanism that drives the relativistic outflows. Iain Steele and colleagues now provide evidence that large-scale, ordered magnetic fields are at least part of the answer. Using a robotic telescope to observe GRB 090102’s optical emission only three minutes after its gamma rays were detected by a satellite, the authors were able to detect significant polarization of the light. This implies the presence of magnetic fields that are organized on a large enough scale also to play a part in accelerating and collimating the relativistic outflows. CONTACT Iain Steele (Liverpool John Moores University, Birkenhead, UK) Tel: +44 151 231 2912; E-mail: ias@astro.livjm.ac.uk Maxim Lyutikov (Purdue University, West Lafayette, IN, USA) N&V author Tel: +1 765 494 5396; E-mail: lyutikov@purdue.edu [3] Evolution: Red Queen revamped (AOP) DOI: 10.1038/nature08630 ***This paper will be published electronically on Nature's website on 09 December at 1800 London time / 1300 US Eastern time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 10 December, but at a later date. *** A report in Nature this week reinterprets a classical evolutionary theory known as Red Queen, and introduces a new way of thinking about speciation. Species arise owing to individual rare events that cause reproductive isolation, rather than because of the mutations they accumulate gradually while ‘running in place’ to keep up with their environment. These events could include biotic changes, but also physical and genetic changes. ‘Red Queen’ is a hypothesis suggesting that every species has to evolve continually, or ‘run in place’, just in order to maintain its fitness relative to other species. Extinction occurs when a species loses a battle against a biotic environment that is constantly changing. Nobody however has ever provided a mechanism by which constant rates of speciation could arise. Mark Pagel and colleagues use the lengths of branches from over 100 phylogenetic trees of animal, plant and fungal species to test the idea that an accumulation of small changes causes speciation against four competing models. They find that the simplest model provides the best description of the branch lengths in 80% of the phylogenies — new species emerge from single rare events, individually sufficient to cause speciation. CONTACT Mark Pagel (University of Reading, UK) Tel: +44 118 378 8900; E-mail: m.pagel@reading.ac.uk [4] Materials science: Tetrahedra get close (pp 773-777) Computer simulations of the packing of hard tetrahedra have uncovered a new type of quasicrystal — the first to be formed from hard or non-spherical particles. The findings, reported in this week’s Nature, show that particle shape is enough, by itself, to produce highly complex, ordered structures. The packing of geometrical solids has been of interest at least since ad 499, the date of the first-known mathematical study of the close-packing of spheres. More recently, the ability to synthesize non-spherical particles ranging in size from nanometres to micrometres has brought practical interest to the packing of three-dimensional shapes. Sharon Glotzer and colleagues have investigated the packing of tetrahedra using thermodynamic computer simulations, which allow the system to evolve naturally, in response to simulated compression, towards high-density configurations. As the simulated pressure increases, the initially disordered ‘fluid’ of tetrahedra undergoes a phase transition to an ordered but non-periodic structure (a quasicrystal) with twelve-fold symmetry. This structure has a packing fraction (the volume fraction occupied by the solid particles) of 83% — achieved by the self-organization of the tetrahedra into groups of five, and then of these groups into layers. In this way, an intricate structure is created from simple hard objects that interact only by excluding one another in space. CONTACT Sharon Glotzer (University of Michigan, Ann Arbor, MI, USA) Tel: +1 734 615 6296; E-mail: sglotzer@umich.edu [5] Earth science: Compositional effects on deep mantle discontinuity (pp 782-785; N&V) Experiments at high temperature and pressure on compositions representative of the Earth’s mantle have shed new light on the phase transition thought to be responsible for a seismic discontinuity observed above the core–mantle boundary. The deepest few hundred kilometres of the mantle, the D″ layer, has seismic properties distinct from those of the overlying mantle, from which it is separated by a laterally varying seismic discontinuity. A good candidate for the origin of this discontinuity is the phase transition from the mineral perovskite to a denser, layered structure called ‘post-perovskite’. Investigating this phase transition experimentally has been challenging, owing to the very high pressures and temperatures required to mimic conditions at the bottom of the mantle. Sang-Heon Shim and colleagues have used a laser-heated diamond-anvil cell to characterize the perovskite/post-perovskite transition in realistic mantle compositions. They report this week in Nature that the pressure–temperature slope of the transition — the ‘Clapeyron slope’ — is consistent with observations of the D″ discontinuity. But the width of the transition — corresponding to the depth range over which the two phases should co-exist in the deep mantle — is much greater than the observed thickness of the D″ discontinuity. The authors conclude that, if the perovskite/post-perovskite boundary is the source of the D″ discontinuity, regions with sharp discontinuities may require distinct compositions, such as a lower aluminium content. CONTACT Sang-Heon Shim (Massachusetts Institute of Technology, Cambridge, MA, USA) Tel: +1 617 324 0249; E-mail: sangshim@mit.edu Kanani Lee (Yale University, New Haven, CT, USA) N&V author Tel: +1 203 432 4354; E-mail: kanani.lee@yale.edu [6] And finally… Sharing childcare makes for yummy mummies (pp 786-789) Parental sharing of childcare and female competition for male attention favour the selection of females with elaborate plumage, a study of African starlings in this week’s Nature suggests. In bird species where males court females, and females are choosy about mates, males tend to be more colourful than females. However, in cooperative breeders, where parents share the load, the two sexes tend to look more alike. Dustin Rubenstein and Irby Lovette demonstrate that this is not because the males have evolved to be less colourful, but because the females have evolved to become more ornate. It’s thought that these fancy feathers may help give females the edge when competing for access to mates or other resources. CONTACT Dustin Rubenstein (Columbia University, New York, NY, USA) Tel: +1 212 854 4881; Email: dr2497@columbia.edu ALSO IN THIS ISSUE… [7] Encounter and extrusion of an intrahelical lesion by a DNA repair enzyme (pp 762-766) [8] Ecoenzymatic stoichiometry of microbial organic nutrient acquisition in soil and sediment (pp 795-798) [9] Cold-induced silencing by long antisense transcripts of an Arabidopsis Polycomb target (pp 799-802) [10] Long-range oncogenic activation of Igh–c-myc translocations by the Igh 3’ regulatory region (pp 803-807) [11] Paradox of mistranslation of serine for alanine caused by AlaRS recognition dilemma (pp 808-812) ADVANCE ONLINE PUBLICATION ***These papers will be published electronically on Nature's website on 09 December at 1800 London time / 1300 US Eastern time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included them on this release to avoid multiple mailings they will not appear in print on 10 December, but at a later date. *** [12] Preparation and detection of a mechanical resonator near the ground state of motion DOI: 10.1038/nature08681 [13] Time-reversal symmetry breaking and spontaneous Hall effect without magnetic dipole order DOI: 10.1038/nature08680 [14] Stomagen positively regulates stomatal density in Arabidopsis DOI: 10.1038/nature08682 GEOGRAPHICAL LISTING OF AUTHORS… The following list of places refers to the whereabouts of authors on the papers numbered in this release. For example, London: 4 - this means that on paper number four, there will be at least one author affiliated to an institute or company in London. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details. CANADA: Montreal: 12 FRANCE Limoges: 10 Paris: 1 Strasbourg: 7 ITALY Ferrara: 2 JAPAN Kyoto: 14 Takasaki: 13 Tokyo: 13 Toyama: 13 Wako: 13 SPAIN Barcelona: 1 UNITED KINGDOM Liverpool: 2 Norwich: 9 Reading: 3 UNITED STATES OF AMERICA California Berkeley: 6 La Jolla: 11 Pasadena: 12 Illinois Chicago: 5 Maryland College Park: 12 Massachusetts Boston: 7, 10 Cambridge: 5, 7 Michigan Ann Arbor: 4 Minnesota Duluth: 8 New Mexico Albuquerque: 8 Santa Fe: 3 New York Ithaca: 6, 12 New York: 6 North Carolina Durham: 8, 11 Ohio Cleveland: 4 Kent: 4 PRESS CONTACTS… From North America and Canada Neda Afsarmanesh, Nature New York Tel: +1 212 726 9231; E-mail: n.afsarmanesh@us.nature.com Katie McGoldrick, Nature Washington Tel: +1 202 737 2355; E-mail: k.mcgoldrick@naturedc.com From Japan, Korea, China, Singapore and Taiwan Mika Nakano, Nature Tokyo Tel: +81 3 3267 8751; E-mail: m.nakano@natureasia.com From the UK/Europe/other countries not listed above Jen Middleton, Nature London Tel: +44 20 7843 4502; E-mail j.middleton@nature.com About Nature Publishing Group (NPG): Nature Publishing Group (NPG) is a publisher of high impact scientific and medical information in print and online. 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