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This press release is copyright Nature.
VOL.454 NO.7202 DATED 17 JULY 2008
This press release contains:
· Summaries of newsworthy papers:
Astrophysics: Magnetic fields and the evolution of galaxies
Mars: Water almost everywhere
Earth science: Setting off a Cretaceous extinction event
Microscopy: Watching the cavorting of once-invisible atoms
And finally… How the brain pays attention
· Mention of papers to be published at the same time with the same embargo
· Geographical listing of authors
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[1] Astrophysics: Magnetic fields and the evolution of galaxies (pp 302-304)
The origin and growth of magnetic fields in today’s galaxies is something of an enigma — very little is known about how they develop over cosmic time, because of the difficulty of detecting magnetic fields in the distant Universe. A paper in this week’s Nature offers a glimpse into these evolutionary mysteries of galaxies.
Francesco Miniati and his colleagues were able to determine that previously measured large-scale magnetic fields are unambiguously associated with normal galaxies. The galaxies lie in front of background quasars, whose light is affected by the magnetic fields in the galaxies, but also potentially by the magnetic field of the galaxy that hosts the quasar. The team demonstrated that the quasar host galaxies are not where the fields are located. The normal galaxies themselves contain magnetic fields with strengths comparable to those seen today at a time when the Universe was only half its present age.
This indicates that magnetic fields build up inside galaxies at an unexpectedly fast rate. Dynamo mechanisms operating partly via interstellar turbulence are thought to be responsible for this growth, and the new findings should provide insight into their performance.
CONTACT
Francesco Miniati (Swiss Federal Institute of Technology - ETH, Zurich, Switzerland)
Tel: +41 44 633 6495; E-mail: [email protected]
[2] Mars: Water almost everywhere (pp 305-309)
The latest data from the Mars Reconnaissance Orbiter point to a more varied mineralogy than previously understood. The results, reported in this week’s Nature by John Mustard and colleagues, are indicative of active, pervasive hydrological processes throughout the crust of early Mars, including the surface.
Our knowledge of the planet’s distant watery past is being refined by the instruments on board the Mars Reconnaissance Orbiter. The presence of interlayered hydrated silicate (phyllosilicate) minerals on Mars preserves a record of past interactions between liquid water and rocks. The phyllosilicates are restricted to ancient terrains dating from the earliest geological era of Mars, the Noachian, and previous data suggested that phyllosilicates existed within a relatively narrow range of mineralogy.
CONTACT
John Mustard (Brown University, Providence, RI, USA)
Tel: +1 401 863 1264; E-mail: [email protected]
[3] Earth science: Setting off a Cretaceous extinction event (pp 323-326; N&V)
Some ninety-four million years ago, the Earth’s oceans suffered a sudden and massive loss of oxygen that wiped out some marine life and buried huge amounts of organic carbon on the sea floor. A paper in this week’s Nature has unearthed how this extreme oceanic anoxic event (OAE), known as OAE2, may have been triggered.
Although it has been suspected that large-scale magmatic activity could be responsible, until now there was little direct evidence to link magmatism with the onset of OAE2. Steven Turgeon and Robert Creaser found that the record of the marine isotope osmium changed sharply at a time corresponding to the start of the event, at two sites 5,500 km apart — one just off northeastern South America and the other in central Italy. Over 97% of the total osmium turned out to be magmatic in origin, a roughly 40-fold increase over conditions before the onset of OAE2.
Their findings indicate that a widespread pulse of magmatic activity occurred at the start of OAE2, which may have triggered the subsequent deposition of large amounts of organic matter in the oceans.
CONTACT
Steven Turgeon (University of Alberta, Edmonton, Canada) Co-author
Tel: +1 780 492.0356; E-mail: [email protected]
Robert Creaser (University of Alberta, Edmonton, Canada) Co-author
Tel: +1 780 492 2942; E-mail: [email protected]
Timothy Bralower (Pennsylvania State University, University Park, PA, USA) N&V author
Tel: +1 814 863 1240; E-mail: [email protected]
[4] Microscopy: Watching the cavorting of once-invisible atoms (pp 319-322; N&V)
The transmission electron microscope has revealed a wealth of important nanoscale features in its time, but catching a glimpse of lightweight individual atoms such as hydrogen and carbon has been beyond its grasp. A paper in this week’s Nature neatly overcomes this problem, providing an exciting opportunity to watch individual building blocks of matter — made of light atoms — at work, and opening the way to real-time investigations of biological molecules in action.
The difficulty in imaging lightweight atoms stems from their signals being drowned out by background signals from the viewing substrate. Alex Zettl and colleagues dramatically enhanced the light atoms' signal-to-background ratio by using a single-layer sheet of graphene, a material that is all but invisible under the microscope, as a sample-support membrane, and by summing several consecutive images of the graphene sheet. And, hey presto — individual hydrogen and carbon atoms appeared as though suspended in free space. Contaminant carbon molecules are also seen absorbing onto the graphene sheet and interacting with defects or travelling across the surface.
The new technique will enable the graphene itself to be studied in greater detail — at a thickness of only one atom, it is the thinnest material ever made. Insight into its atomic-scale defects could guide nanoelectronic applications of this interesting material.
CONTACT
Alex Zettl (University of California, Berkeley, CA , USA) Author
Tel: +1 510 642 4939; E-mail: [email protected]
Jannik Meyer (University of Ulm, Germany) Co-author
Tel: +49 731 50 22937; E-mail: [email protected]
John Silcox (Cornell University, Ithaca, NY, USA) N&V author
Tel: +1 607 255 3332; E-mail: [email protected]
[5] And finally… How the brain pays attention (AOP)
DOI: 10.1038/nature141
***This paper will be published electronically on Nature's website on 16 July 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 17 July, but at a later date. ***
Neuroscientists have identified the brain circuits involved in focusing attention on a particular location or object in our visual world. The process, which involves changes in the behaviour of cells within the brain’s visual cortex, is enhanced by the activity of a ‘messenger molecule’ called acetylcholine.
Researchers led by Alex Thiele trained macaque monkeys to detect an object flashing on, while ignoring another one flashing on nearby. The research team then injected tiny amounts of acetylcholine, or chemicals that specifically block acetylcholine receptors, into the visual cortex and monitored changes in both the behaviour of the brain cells and the monkeys’ performance.
The enhancing effect of acetylcholine on attention involves a certain class of acetylcholine receptor, known as muscarinic receptors, the researchers report in this week’s Nature. The other major class of receptors was not found to be involved, suggesting that the study may have pinpointed the brain mechanism that allows us to block out other stimuli while trying to concentrate on a particular thing.
CONTACT
Alex Thiele (University of Newcastle upon Tyne, UK)
Tel: +44 191 222 7564; E-mail: [email protected]
ALSO IN THIS ISSUE…
[6] Positive feedback of G1 cyclins ensures coherent cell cycle entry (pp 291-296; N&V)
[7] Generation of Fock states in a superconducting quantum circuit (pp 310-314)
[8] Climbing the Jaynes–Cummings ladder and observing its √n nonlinearity in a cavity QED system (pp 315-318)
[9] Coherent ecological dynamics induced by large-scale disturbance (pp 331-334)
ADVANCE ONLINE PUBLICATION
***These papers will be published electronically on Nature's website on 16 July 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 17 July, but at a later date. ***
[10] On the nature of partial agonism in the nicotinic receptor superfamily
DOI: 10.1038/nature07139
[11] Internal brain state regulates membrane potential synchrony in barrel cortex of behaving mice
DOI: 10.1038/nature07150
[12] The behaviour of Drosophila adult hindgut stem cells is controlled by Wnt and Hh signaling
DOI: 10.1038/nature07156
[13] Molecular basis of the copulatory plug polymorphism in Caenorhabditis elegans
DOI: 10.1038/nature07171
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:
Edmonton: 3
Sherbrooke: 8
Toronto: 1
FRANCE
Orsay: 2
GERMANY
Munich: 7
NETHERLANDS
Nijmegen: 5
SWITZERLAND
Lausanne: 11
Sauverny: 1
Zurich: 1, 8
UNITED KINGDOM
London: 5, 10
Newcastle: 5
Sunderland: 5
UNITED STATES OF AMERICA
Arizona
Flagstaff: 2
Tempe: 2
California
Berkeley: 4
Los Angeles: 12
Mountain View: 2
Pasadena: 2
Santa Barbara: 7
Colorado
Boulder: 2
Denver: 2
District of Columbia
Washington: 2
Maine
Brunswick: 13
Maryland
Greenbelt: 2
Laurel: 2
Missouri
St Louis: 2
New Jersey
Princeton: 13
New Mexico
Los Alamos: 1
New York
New York: 6
Rhode Island
Providence: 2
Texas
Austin: 9
Houston: 2
Virginia
Herndon: 2
PRESS CONTACTS…
From North America and Canada
Katherine Anderson, Nature New York
Tel: +1 212 726 9231; E-mail: [email protected]
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: [email protected]
From Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
From the UK/Europe/other countries not listed above
Jen Middleton, Nature London
Tel: +44 20 7843 4502; E-mail [email protected]
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