Nature press release for 12 September issue

[2] CLIMATE: TURBULENCE IN CLOUDS MAKES RAIN (pp151-154)

Researchers in Israel have figured out how clouds whip up a rainstorm. They say that air turbulence in clouds helps droplets of water to coalesce until they become big enough to fall as rain. The complex calculations performed by the researchers yield potential rules of thumb to help meteorologists to predict how quickly and abundantly rain might develop in different types of cloud.
For a cloud to shed rain, the droplets have to grow large enough to fall quickly through the air. At first this growth happens slowly, by the droplets harvesting water vapour from the surrounding air. Once the droplets reach about 20 micrometres across, further growth occurs mainly by coalescence with other droplets. Droplets of fine drizzle are 200 micrometres or so across, and fall at a speed of about half a metre per second. Cloud droplets about a millimetre across plunge earthwards at about nine metres per second.
Gregory Falkovich and colleagues at the Weizmann Institute of Science in Rehovot, Israel, use approximate mathematical relations connecting such factors as the speed and size of droplets carried in turbulent air to deduce how vortices alter the rate of collisions. They find that even for small droplets in moderately turbulent air, the collision rate, coalescence and growth of droplets can be much greater than it would be in still or smooth-flowing air. In particular, they find that collisions are increased by a `slingshot` effect. A train of droplets is accelerated by the air flow, and then released from it in a kind of jet.
CONTACT:
Gregory Falkovich tel (until 11/09/02) +972 8934 2830 (after 11/09/02) +1 609 279 2831, e-mail fnfal@wicc.weizmann.ac.il

[3] HEALTH: EURO CORROSION IRRITATES (p132)

Euro coins can cause bad skin reactions in people with nickel allergies, although some other coins containing comparable amounts of nickel, such as the Swiss franc, do not. In a Brief Communication to this week`s Nature, Frank Nestle of the University of Zurich, Switzerland, and colleagues have come up with an explanation.
The two-alloy structure of one- and two-euro coins makes them prone to release large amounts of nickel in human sweat — as much as 320 times the quantity allowed under the European Union Nickel Directive, and even more than pure nickel does under the same conditions.
Nestle and colleagues show that it is the coins` central `pill` and outer `ring` design that is responsible for this enhanced nickel release. The yellow and white alloys contain different amounts of nickel, copper and zinc, which encourages corrosion as metal ions flow from one alloy to the other during prolonged exposure to sweat — a process that eventually damages the coloration of the coins. The rate of nickel release is roughly the same from the yellow and white parts, even though the former contains 80% less nickel.
CONTACT:
Frank O. Nestle tel +41 1 255 20 86, e-mail nestle@derm.unizh.ch

[4] TECHNOLOGY: OPTICAL TOOLKIT GROWS (pp145-147; N&V)

Optical tweezers use a tightly focused laser beam to attract and trap tiny particles whose refractive index is greater than that of the surrounding medium. They are now important tools in physics, biology and chemistry, and have been used to unravel DNA, and to study the structure of chromosomes and colloids.
In this week`s Nature, K. Dholakia and colleagues from the University of St Andrews, Fife, UK, report a new addition to the optical toolkit that may make it possible to use optical tweezers to create three-dimensional arrays of particles, as required in micromachines or ‘lab-on-a-chip’ microstructures.
These new tweezers use a self-healing Bessel beam — a beam of light that is non-diffracting and re-forms itself after encountering an obstacle — to trap and move objects in separate sample chambers a few millimetres apart aligned in the direction of beam propagation.
"Bessel-beam tweezers could be used to sort the oval-shaped particles produced in the micro-dissection of chromatin (made up of DNA and proteins) through tiny openings or pores," says Martin Hegner of the University of Basel, Switzerland, in an accompanying News and Views article. "For cell sorting, these tweezers have much enhanced guiding capabilities, compared to systems used so far," he concludes.
CONTACT:
K. Dholakia tel +44 1334 431184, e-mail Kd1@st-and.ac.uk
Martin Hegner tel +41 61 267 37 61, e-mail martin.hegner@unibas.ch

CLIMATE: INSIGHT INTO WATER

The distribution of water on Earth is vitally important for humankind and life in general, as illustrated by this month`s Insight reviews supplement on the interactions between climate and the hydrologic cycle, past, present and future.
Of the two most important climate parameters, temperature and precipitation, the latter is simply water and the former is dominated by water in its role of distributing heat over the planet. A large number of feedback cycles, some of them opposite in effect to others, are involved in this distribution of the incoming energy from the Sun. Water vapour in the atmosphere is the most important greenhouse gas, but clouds and ice sheets can cool the Earth by reflecting energy back to space. Ocean currents transport heat away from the tropics and release it in high latitudes, but they also bring moisture which — under suitable conditions — can induce the growth of ice sheets. Water acts at once as the venetian blind of our planet, its central heating system and its fridge.
How the balance between the multitude of processes will evolve in a changing climate is as important a question as it is difficult. Water in its various forms has always worked as a great amplifier of changes — such as variations in insolation or tectonic changes — that are imposed on the climate system. Similarly, water is intimately involved in the way the more recent addition of anthropogenic greenhouse gases affects climate.

PDFs of the papers in this Insight can be found on http://press.nature.com. They are…

 Reducing uncertainty about carbon dioxide as a climate driver
 The hydrologic cycle in deep-time climate problems
 Links between climate and sea levels for the past three million years
 Ocean circulation and climate during the past 120,000 years
 A satellite view of aerosols in the climate system
 Constraints on future changes in climate and the hydrologic cycle

[5] LIFELINES: NEW CLASS OF TUMOUR SUPPRESSOR (pp162-167; N&V)

The Lkb1 protein is an unusual tumour suppressor, Ronald A. DePinho of the Dana-Farber Cancer Institute and Harvard Medical School, Boston, and colleagues report in this week`s Nature. They have developed mice lacking Lkb1, the gene mutated in patients with Peutz–Jeghers gastrointestinal polyposis and cancer syndrome.
Lkb1 seems to have some cancer-causing, and some cancer-preventing, activity. Lkb1 deficiency somehow promotes perpetual cell growth but prevents malignant transformation. This evidence places the gene in "a distinct class of tumour suppressors," says DePinho`s team.
In an accompanying News and Views article, Louise van der Weyden, Jos Jonkers and Allan Bradley of the Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK, discuss these results and their possible implications.
CONTACT:
Ronald A. DePinho tel +1 617 632 6098/6091, e-mail Ron-_depinho@dfci.harvard.edu
Allan Bradley tel +44 1223 834244, e-mail abradley@sanger.ac.uk

[6] SPACE: PULSARS NOT SO ANOMALOUS (pp142-144; N&V)

Two X-ray bursts have been observed from the direction of an anomalous X-ray pulsar (AXP), implying a close, possibly evolutionary relationship between AXPs and soft gamma-ray repeaters (SGRs), V. M. Kaspi of McGill University, Montreal, Canada, and colleagues report in this week`s Nature. This supports the idea that AXPs are magnetars — young neutron stars with ultra-high magnetic fields.
Discovered in 1981, AXPs were for many years thought to be an unusual class of accreting neutron star. That model became increasingly at odds with observation. The only alternative explanation has been that AXPs are magnetars. This explanation looked problematic because AXPs appeared not to share the bursting properties characteristic of SGRs, which have been convincingly shown to be magnetars.
"So it seems magnetars do exist," says Shri Kulkarni of Caltech, Pasadena, California, in an accompanying News and Views article. "Astronomers can feel quite satisfied to have postulated, discovered and confirmed a new class of cosmic object".
CONTACT
Victoria Kaspi tel +1 514 398 6412, e-mail vkaspi@physics.mcgill.ca
Shri Kulkarni tel +1 626 395 4010, e-mail srk@astro.caltech.edu

[7] …AND FINALLY: FRUSTRATED FANS MAKE WAVES (pp131-132)

In a Brief Communication to this week`s Nature, researchers reveal the secret to starting a Mexican wave: a pocket of frustrated fans at a football game.
During Mexican waves, a group of spectators leap to their feet with arms outstretched — and sit down again as people in the neighbouring section of the stand jump up. Tamas Vicsek of the University of Budapest in Hungary and his team studied footage of 14 Mexican waves in football stadia and built a mathematical model that mimics them.
They found that it takes a critical mass of 25–35 people to get the wave started. And Vicsek predicts that waves are more likely to occur when spectators aren`t already over-excited — such as during flat periods in the game.
Vicsek hopes that similar studies could help predict when excited crowds will run out of control, such as during riots or post-match brawls.
CONTACT:
T. Viscek tel +36 1 372 2755, e-mail vicsek@angel.elte.hu

ALSO IN THIS ISSUE…

[8] RAD6-dependent DNA repair is linked to modification of PCNA by ubiquitin and SUMO (pp135-141; N&V)

[9] Mechanical milling assisted by electrical discharge (pp147-151)

[10] Macroecological patterns of phytoplankton in the northwestern North Atlantic Ocean (pp154-157; N&V)

[11] Coding of smooth eye movements in three-dimensional space by frontal cortex (pp157-162)

[12] SINAT5 promotes ubiquitin-related degradation of NAC1 to attenuate auxin signals (pp167-170)

[13] L23 protein functions as a chaperone docking site on the ribosome (pp171-174)

[14] Oxidative demethylation by Escherichia coli AlkB directly reverts DNA base damage (pp174-178)

[15] AlkB-mediated oxidative demethylation reverses DNA damage in Escherichia coli (pp178-182)

[16] Comprehensive proteomic analysis of the human spliceosome (pp182-185)

[17] Nanometre-size products of uranium bioreduction (p134)

AOP PUBLICATION

***The following paper will be published electronically on Nature`s website on 11 September at 1900 London time / 1400 US Eastern time (which is also when the embargo lifts) as part of the AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print in the September 12 issue, but at a later date.***

[18] Active genes are tri-methylated at K4 of histone H3 (DOI: 10.1038/nature01080) (http://dx.doi.org/10.1038/nature01080)

GEOGRAPHICAL LISTING OF AUTHORS

The following list of places refers to the whereabouts of authors on the papers numbered in this release. 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.

AUSTRALIA
Wollongong: 9

CANADA
Dartmouth: 10
Montreal: 6

GERMANY
Dresden: 7
Freiburg: 13
Heidelberg: 13
Martinsried: 8

HUNGARY
Budapest: 7

ISRAEL
Rehovot: 2

JAPAN
Sapporo: 11
Yokosuka: 17

NORWAY
Oslo: 15

RUSSIA
Novosibirsk: 2

SINGAPORE
National University of Singapore: 12

SWITZERLAND
Basel: 8
Zurich: 3, 13

UNITED KINGDOM
Cambridge: 18
Oxford: 18
South Mimms: 14
St Andrews: 4

UNITED STATES OF AMERICA

Alabama
Huntsville: 6

California
Berkeley: 17

Illinois
Argonne: 17
Chicago: 11

Maryland
Baltimore: 1
Bethesda: 12

Massachusetts
Boston: 5, 16
Cambridge: 6, 16, 18

Michigan
East Lansing: 14

New York
New York: 12

Pennsylvania
Philadelphia: 18

Wisconsin
Madison: 17

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