gene linked to puberty found
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Frozen islands may remain in Antarctic
SOME of the West Antarctic ice sheet may survive as the climate warms – although the parts most likely to float off could still raise sea levels globally by more than 3 metres.
Glaciologists had feared that when warmer water melts floating ice shelves, the entire sheet will be released into the ocean and will melt too, raising sea levels by up to 5 metres . A recent study found the ice sheet is probably doomed if the seas warm by more than 5 °C.
Now Jonathan Bamber at the University of Bristol, UK, says that one-third of the ice sheet might remain , mostly because it rests on bedrock that is above sea level ( Science, DOI: 10.1126/science.1169335 ). The two-thirds lost, however, could still raise sea levels by 3.3 metres. The loss of Antarctic ice would also shift the Earth’s gravitational pull, causing water to pile up in the northern hemisphere and boosting sea-level rise there .
In March, Bamber argued that the Greenland ice sheet is also more resistant to warming than previously thought. But most predictions still put global sea-level rise at around 1 metre by 2100 – with more to follow.
Genes for timing of puberty and menopause found
IT HAS long been known that some women’s biological clocks tick faster than others. Now several gene variants that control when an individual has her first and last period have been identified.
Groups from the US, UK, Iceland and the Netherlands, working independently, scanned the genomes of thousands of women and then compared the results with their age when menstruation began. All four teams found that variations near a gene called LIN28B were associated with the timing of
a girl’s first period. Two of the teams also identified several gene variants associated with advanced or delayed menopause. Each team’s research will be published in this week’s issue of Nature Genetics.
LIN28B is also involved in determining a person’s height . This may help to explain why girls whose first period occurs later end up taller than those who start menstruating younger, says André Uitterlinden at the Erasmus Medical Center in Rotterdam, the Netherlands.
This points to a more general
RAINDROPS have been seen falling
from the sky faster than thought
possible. The finding suggests that
forecasters could be miscalculating
how much it rains.
Conventional wisdom holds that
all raindrops fall at their terminal
velocity – a freely falling object’s
maximum speed – and that larger
drops fall faster than smaller ones .
To test this, Fernando García-García of
the National Autonomous University
of Mexico in Mexico City and his
colleagues traced the shadows of
raindrops. In a paper to appear in
Geophysical Research Letters, they
report that up to half exceeded their
expected terminal velocity, and some
fell 10 times as fast.
“Others had detected this before,
but everybody disregarded it,” says
García-García. The drops may fall at
“super-terminal” speeds if they are
fragments of speedy larger drops.
Forecasters estimate the volume
of rainfall by using radar to measure
the speed at which raindrops fall –
and hence deducing their size. By
getting this wrong they may
be overestimating rainfall by up to
20 per cent, the team says, and so
overstating risks of flooding.
Water falls faster than it oughta
role for LIN28B in development, says Ken Ong at the UK’s Medical Research Council Epidemiology Unit in Cambridge. His team found a variant associated with earlier breast development in girls and earlier voice-breaking in boys. “Showing it in boys means [LIN28B] is fundamental, not just to menstruation, but to the timing of growth as well,” he says.
The findings could lead to treatments for diseases linked to prolonged or shortened fertility, such as breast cancer and osteoporosis.
How to grow a frost garden
NOT much grows in the icy polar
regions, but for the fern-like clusters
of ice crystals called frost flowers
this is the perfect environment,
especially when it’s still and dry.
Frost flowers bloom on fresh,
thin sea ice, which makes it difficult
to get close enough to study them.
It was assumed that these salty
structures were similar to hoar
frosts, which form when water from
supersaturated air – perhaps in the
form of freezing fog – is deposited
as ice crystals on a surface.
However, Grae Worster and
Robert Style of the University of
Cambridge found that frost flowers
form mostly in still, dry air. The key
factor is air that is much colder – by
around 20 °C – than the water below
the ice , they say in a paper to appear
in Geophysical Research Letters.
Under these extreme
circumstances ice vaporises into
the dry air and then refreezes in
the form of a frost flower. The pair
confirmed this by recreating such
conditions in the laboratory. They
grew frost flowers from fresh water
at 0 °C by cooling the surrounding
air to around −25 °C.
The finding could change the
way past climate is inferred from
ice cores. High levels of salt in frost
flowers have been assumed to come
from sea spray kicked up by storms,
but it now seems that these flowers
can bloom in calm conditions.
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23 May 2009 | NewScientist | 15