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This press release contains:
* Summaries of newsworthy papers:
Commentary: Gender agenda
Atmospheric chemistry: Air’s ‘radical’ self-cleaning ability
Relics: Molluscs of mat destruction
Quantum electronics: Hall of spin
Biochemistry: Surprisingly, DNA has trouble unwinding
Electronics: Wet is best
And finally… An atom abacus fashioned by light
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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Commentary: Gender agenda (pp 133-136)
In a challenge to recent public comments on women in science from the likes of Larry Summers, Steven Pinker and Peter Lawrence, a Commentary in this week’s Nature explains the problems with their hypothesis.
Ben A. Barres - a female-to-male transgendered scientist - analyses the suggestion that women are not advancing in science because of an innate inability. He challenges the arguments that women are less competitive, risk adverse, less abstract and too emotional to succeed in science, and argues instead that discrimination is the primary factor. He points to published evidence that supports this view, as well as to his personal experiences drawn from a scientific career that spans both female and male perspectives.
Barres calls for several changes. To help younger scientists, there needs to be an evaluation of bias during selection processes for awards, grants and faculty positions. Barres lauds the National Institutes of Health for recently revamping their Pioneer Award to take away evaluation biases - just a few small changes made a significant difference in the outcome, with the number of women and people from minority backgrounds winning the award rocketing from zero to nearly 40%. Barres notes that the Howard Hughes Medical Institute are currently looking at how they award career-related fellowships, and hopes they will make similar changes. For talented women, academia is all too often not a meritocracy, he says.
Crucially, there should be an end to the negative messages conveyed to female students from an early age, argues Barres. More scientists - both male and female - need to speak out against discrimination: indeed, the exact opposite of the messages conveyed by the likes of Summers, Pinker and Lawrence. This, coupled with encouragement and positive mentoring, will ensure that talented scientists - whether in a minority group or not - can go on to reach their full potential.
CONTACT
Ben A Barres (Stanford University School of Medicine, CA, USA)
Tel: +1 650 723 5966; E-mail: [email protected]
[1] Atmospheric chemistry: Air’s ‘radical’ self-cleaning ability (pp 184-187; N&V)
Can we continue to rely on the cleansing power of hydroxyl radicals (denoted OH) - the ‘detergent of the atmosphere’ - in the face of increased pollution and the effects of climate change? Or might this vital ingredient get used up? These radicals react quickly with many other chemical compounds in the atmosphere, including pollutants, and thus help to ‘clean’ the air of such contaminants. In this week’s Nature, Franz Rohrer and Harald Berresheim report the first long-term measurements of OH levels in the atmosphere, collected between 1999 and 2003. Because OH radicals react so quickly, their atmospheric concentration is low and is not easy to measure; reliable measurements have been possible only since the early 1990s.
They discover that - to their surprise - changes in OH levels during the day or over the seasons seem to be linked to a single factor: the intensity of solar ultraviolet (UV) radiation. From this, the researchers infer that there is no detectable long-term change in OH concentrations over their study period.
At first glance, the link between OH levels and UV intensity might not seem so surprising, as OH radicals are formed when UV light splits apart molecules of atmospheric ozone. But their subsequent reactions with other trace gases are very complex, and indeed the researchers confess that they are still not fully understood. It seems that the factors that might affect the production or consumption of OH balance out so that there is a stable and predictable dependence of OH levels on UV intensity: fluctuations in its concentration are much smaller than might be expected, and seemingly immune to other changes in the chemical composition of the atmosphere.
CONTACT
Franz Rohrer (Forschungszentrum Julich, Germany)
Tel: +49 2461 616511; E-mail: [email protected]
Paul O Wennberg (California Institute of Technology, Pasadena, CA, USA)
Tel: +1 626 395 2447; E-mail: [email protected]
[2] Relics: Molluscs of mat destruction (pp 159-163; N&V)
A dramatic re-interpretation of an ancient creature is reported in Nature this week. The soft-bodied Odontogriphus omalus is an oddity from the Middle Cambrian Burgess Shale of Canada that offers an insight into the rich early history of animals. Odontogriphus now turns out to be a very early representative of the Mollusca, the group of animals that includes snails, bivalves and squid. The researchers use this information to suggest that many other early, enigmatic fossils were also molluscs. If true, this shows that molluscs - and therefore many other animal groups - had evolved many tens of millions of years earlier than had been thought.
Jean-Bernard Caron and colleagues looked at many new specimens of Odontogriphus and found that it had a radula - a hard, rasp-like organ used to strip algae from rocks. The radula is a characteristic feature of molluscs: modern snails use the same organ to munch on your sunflowers. Thus, re-interpreted as a shell-less mollusc that grazed the algal mats of ancient seafloors, Odontogriphus opens a new window on the earliest history of one of the most important animal groups. The research starts to show a picture of a very ancient history of molluscs and, for the first time, a decent overview of the evolution of a vitally important group of creatures.
CONTACT
Jean-Bernard Caron (Royal Ontario Museum, Toronto, Canada)
Tel: +1 416 586 5593; E-mail: [email protected]
Please note the author is travelling and it may be easier to reach David M Rudkin, who will be available from 10 July (and may also have intermittent email access before then):
Tel: +1 416 586 5592; E-mail: [email protected]
Stefan Bengtson (Swedish Museum of Natural History, Stockholm, Sweden) N&V author
Tel: +46 8 5195 4220; E-mail: [email protected]
[3] Quantum electronics: Hall of spin (pp 176-179; N&V)
A new approach for manipulating a quantum-mechanical property of electrons called spin could help to usher in a new information-processing technology called spintronics.
The spin of an electron can take one of two values, characterized as 'up' and 'down', and magnetic fields can be used to ‘flip’ their spin. This raises the possibility of encoding information in the spins of electrons that constitute an electrical current. Today's electronics transmit information in the form of electrical pulses: but currents with particular electron spins - so-called spin-polarized currents - could carry additional information that could be manipulated and processed in new ways. This is the vision for spintronic technology.
Sergio Valenzuela and Mike Tinkham publish in Nature this week the first direct detection of a particular spin-related effect in electronics that was predicted in 1971. They apply an electric field to a current-carrying wire, which makes the electrons with one spin drift in one direction perpendicular to the applied field, while electrons with the opposite spin drift in the other direction. If the current is spin-polarized, so that there is more of one type of spin than the other, this creates an imbalance of charge from one side of the wire to the other, setting up a voltage. The effect is analogous to the Hall effect, in which an applied magnetic field deflects an ordinary current sideways, and is known as the spin Hall effect.
The researchers have observed this effect in a microelectronic circuit. They believe it provides the opportunity to detect and manipulate spins without using magnetic fields, leading to all-electronic ways of building spintronic devices.
CONTACT
Sergio Valenzuela (Massachusetts Institute of Technology, Cambridge, MA, USA)
Tel: +1 617 407 5719; E-mail: [email protected]
Andrew D Kent (New York University, NY, USA)
Tel: +1 212 998 7773; E-mail: [email protected]
[4] Biochemistry: Surprisingly, DNA has trouble unwinding (AOP)
DOI: 10.1038/nature04974
***This paper will be published electronically on Nature's website on 12 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 13 July, but at a later date.***
After some half a century of scrutiny, you might expect the DNA molecule to have few surprises left in store. But biochemists in California have discovered something quite remarkable about this most familiar of molecules - if you stretch this helical structure, it actually winds itself more tightly.
It sounds counterintuitive, but as Carlos Bustamante and his colleagues report in a paper to be published online by Nature this week, the DNA double helix winds more tightly when gently stretched. Only if you really tug at it does its spiral begin to unfurl. This is in contrast to almost all other helical structures - such as an old-fashioned sweet wrapper, for instance, which unwinds when you pull on its ends.
The researchers made their discovery by studying single DNA molecules with tiny stretching forces applied to them. The discovery may also explain some puzzling real-life examples of cellular DNA structures that seem to be both taut and yet tightly wound.
CONTACT
Carlos Bustamante (University of California Berkeley, CA, USA)
Tel: +1 510 643 9706; E-mail: [email protected]
[5] Electronics: Wet is best (pp 180-183)
Making electronic devices in a test tube using 'wet chemistry' is potentially cheaper and cleaner than the traditional method of depositing thin films of semiconductors and metals from gases in high-vacuum conditions. But the chemical solution-based methods developed so far tend to produce devices that don't perform as well as their conventionally fabricated counterparts.
Edward Sargent and colleagues report in Nature this week how they could change this. They cast photodetectors from solution that are even more sensitive to light than the best of today's conventionally made devices. The researchers used a technique called spin-coating to spread a thin film of tiny semiconductor crystals, each just a few nanometres across, onto glass plates. When contacted by gold electrodes, the dried films showed a capacity for light detection that was around ten times better than devices made by traditional expensive methods. The results demonstrate that solution-processed electronics need not sacrifice performance for the sake of cost.
CONTACT
Edward Sargent (University of Toronto, Canada)
Tel: +1 416 946 5051; E-mail: [email protected]
[6] And finally… An atom abacus fashioned by light (pp 151)
Individual atoms can be moved along a line like beads on an abacus, using a technique described by Arno Rauschenbeutel and colleagues in a Brief Communication in Nature this week. The researchers report that their method can be used to sort and space atoms one by one, and might be applicable as a memory device in which quantum information is stored in strings of equidistant atoms.
The team use laser beams to trap the atoms, which are captured in 'wells' created by allowing opposing laser beams to interfere. Following this manipulation the distribution of atoms along the horizontal trap axis is represented as a row of bright spots about half a micrometre apart. The researchers trap atoms of caesium cooled to less than a thousandth of a degree above absolute zero. This cooling is needed to prevent the atoms from jumping out of the wells.
A particular atom can be selected and moved from one trap to the next along the horizontal row by using a second set of traps in a vertical plane. An atom held at the intersection of the vertical and horizontal rows of traps can be translated horizontally by shifting the vertical row. In this way, the researchers were able to move atoms placed in the horizontal traps with random interatomic distances in the horizontal wells until they were all in a line with an identical distance between consecutive atoms.
CONTACT
Arno Rauschenbeutel (University of Bonn, Germany)
Tel: +49 228 733471; E-mail: [email protected]
ALSO IN THIS ISSUE…
[7] Clarifying the mechanics of DNA strand exchange in meiotic recombination (153-158)
[8] Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts (pp 172-175)
[9] Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip (pp 188-191)
[10] The cargo-binding domain regulates structure and activity of myosin 5 (pp 212-215)
ADVANCED ONLINE PUBLICATION
***This paper will be published electronically on Nature's website on 12 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 13 July, but at a later date.***
[11] Card9 controls a non-TLR signaling pathway for innate anti-fungal immunity (AOP)
DOI: 10.1038/nature04926
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
Toronto: 2, 5
GERMANY
Bonn: 6
Dusseldorf: 11
Hohenpeissenberg: 1
Julich: 1
Munich: 11
JAPAN
Tokyo: 9
NORWAY
Bergen: 2
RUSSIA
St Petersburg: 8
UNITED KINGDOM
Leeds: 10
UNITED STATES OF AMERICA
California
Berkeley: 4
Stanford: 4, 9
Maryland
Bethesda: 10
Greenbelt: 8
Massachusetts
Cambridge: 3, 4
Woods Hole: 2
New Mexico
Los Alamos: 8
New York
New York: 7
PRESS CONTACTS…
For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: [email protected] <mailto:[email protected]>
For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected] <mailto:[email protected]>
For the UK/Europe/other countries not listed above
Helen Jamison, Nature London
Tel: +44 20 7843 4658; E-mail [email protected] <mailto:[email protected]>
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