20 | New Scientist | 22 August 2020Marine biologyUS kids are eating
more fast foodOVER a third of children in the
US eat fast food on any given day,
according to survey results
compiled by the US Centers for
Disease Control and Prevention.
Cheryl Fryar at the CDC’s
National Center for Health
Statistics and her colleagues have
been tracking the fast-food intake
of young people in the US since- The team uses data from a
large national study that involves
All-consuming fire is
three flames in oneWE ARE a step closer to solving the
mystery of the blue whirl flame,
a soot-free flame that consumes
all the fuel it encounters.
The phenomenon was
discovered in 2016 by researchers
who were investigating efficient
ways of using fire to clean up
oil spills in the ocean. They were
experimenting with fire whirls –
whirlwinds naturally induced by
fire – and accidentally generated
a clean, whirling, blue flame.
Since then, people have been
trying to determine the structure
of this mysterious blue whirl
flame, in the hope of harnessing it.
Joseph Chung and Xiao Zhang
at the University of Maryland,
College Park, and their colleagues
created a computer simulation of
the experimental conditions that
generated the original flame. By
gradually adjusting parameters,
such as the ratio of fuel to air, andPhysics HealthGREY reef sharks chill with the
same buddies in the same spot
for years, a four-year study at
the remote Palmyra Atoll in the
Pacific Ocean has revealed.
Yannis Papastamatiou at
Florida International University in
Miami and his colleagues tagged
about 40 sharks with acoustic
transmitters that each emit a
unique high-frequency sound.
A network of 65 receivers
recorded which sharks came within
300 metres or so of any receiver.
The recordings reveal that the
social groups of grey reef sharks
are remarkably stable: the same
individuals associate year after year
and movements between groups
are rare (Proceedings of the Royal
Society B, doi.org/d6nn).
“They purposely associate
with the same individuals,” saysPapastamatiou. That suggests
that they can recognise other
sharks individually.
Grey reef sharks (Carcharhinus
amblyrhynchos) are most active
at night. During the day, they return
to a particular spot on the reef,
forming groups of 20 or so. They
do catch prey during the day, but
feed more at night.
It isn’t known whether the
same individuals hunt together
when they leave the home area
at night. The grey reef sharks at
Palmyra catch most of their
prey in open waters, too far
from the reef to be detected
by the receiver network.
Grey reef sharks are unusual
among sharks in being social
animals. Other species, such as the
great hammerhead, spend most of
their time alone. Michael Le PageReef sharks hang out with
the same friends for years
interviewing and assessing
the health of a nationally
representative group of about
5000 individuals annually.
Volunteers describe their eating
habits, or those of their young
children, in face-to-face interviews.
Snacks or meals described as
“restaurant fast food” or “pizza”
were classified as fast food.
Data collected between 2015
and 2018 revealed that, on average,
young people aged between
2 and 19 got about 14 per cent of
their daily calories from fast food.
Only 11 per cent of young people
obtained less than 25 per cent of
their daily calories from such
meals. Between 2009 and 2010,
children obtained just under 11 per
cent of their daily calories from it.
Fast-food consumption could
have lasting health impacts.
Studies suggest that children who
eat more fast food have more fat
and sugar in their diets and are
more likely to put on fat, putting
them at greater risk of obesity
in adulthood. Jessica Hamzeloucomparing it with video footage
of the blue whirl, the researchers
were able to simulate the flame
and analyse its structure.
They discovered that the blue
whirl is the result of three types
of flame merging. These include
an invisible outer flame, where
there is more oxygen than fuel,
and two visible inner flames,
where the ratio of fuel to oxygen
is higher (Science Advances,
DOI: 10.1126/sciadv.aba0827).
Knowing its constituent flame
types could enable the blue whirl
to be recreated without needing
to go through the dangerous, and
hard-to-contain, fire whirlwind
stage to produce it, says Chung.
It could also lead to
combustion that is cleaner
and produces fewer pollutants.
“The blue whirl itself shows
a possible way of burning that
could greatly reduce this pollution
and so we are very motivated
to explore this potential for
cleaner combustion,”says
Zhang. Layal LiverpoolDO
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ESNews In brief