20 | New Scientist | 28 November 2020Animal behaviourSolar power used to
sterilise surgical kitFOR medics performing surgery
in remote regions, sterilised
equipment isn’t always readily
available. Now, a portable, solar-
powered device can generate the
conditions to sterilise medical
instruments in such spots.
Lin Zhao at the Massachusetts
Institute of Technology and his
team have developed a device that
can power an autoclave, a machine
used to sterilise equipment withAI can tell if you
have tinnitusAN ARTIFICIAL intelligence has
been devised to tell from brain
imaging if you have tinnitus.
Mehrnaz Shoushtarian at the
Bionics Institute in Melbourne,
Australia, and her colleagues have
developed an algorithm that can
spot the presence of tinnitus
with 78 per cent accuracy and
tell between mild and severe
forms with 87 per cent accuracy.
Traditional diagnosis can rely
heavily on subjective tests.
The team used a neuroimaging
technique known as functional
near-infrared spectroscopy (fNIRS)
on 25 people with chronic tinnitus
and 21 without the condition. This
measures blood flow and oxygen
levels in certain brain regions,
which correspond to brain activity.
It was used while participants
were given visual and auditory
stimuli. Many visual-auditory
neural pathways interact, both inHealth^ MedicineVERY hungry monarch butterfly
caterpillars get hangry, resulting
in them headbutting and lunging
at each other in an attempt to
secure food.
“The less food that is present,
the higher their level of aggression,”
says Elizabeth Brown at Florida
Atlantic University.
Monarch caterpillars (pictured)
are found across North and Central
America. They only eat milkweed
leaves. Brown and her team gave
the caterpillars three different
amounts of food and found they
attacked each other significantly
more when the leaves were scarce.
Larger monarch caterpillars –
those in the final stages before
starting to transform into
butterflies – often showed the
most aggression, probably
because they need more food,says Brown. “There’s a clear
winning caterpillar and losing
caterpillar,” she says. “This often
scales with their size.”
The hungry caterpillars only
attack when their target is actively
feeding – an attack never occurred
while a rival caterpillar was resting.
The attacker seeks to disrupt
feeding and claim a food source
for itself (iScience, doi.org/fjzf).
“You can often see a single
caterpillar strip down an entire plant
of its leaves,” says team member
Alex Keene, also at Florida Atlantic
University. “So, there is a big cost to
these caterpillars if there are three
of them on a plant with you.”
Many animals become aggressive
when competing for food. The
team hopes to learn more about
the genetic basis of this by studying
the caterpillars. Karina ShahCaterpillars lash out
when they get hangry
the use of high-pressure steam.
The new tool works even in hazy
or cloudy conditions. It consists
of a solar component that heats
water to generate steam, which is
connected to a pressure chamber.
A key component of the solar
heater is an aerogel – a solid,
foam-like material – made from
silica. The gel is transparent, so it
doesn’t impede the absorption
of sunlight, but it does act as an
insulator to prevent heat loss.
To be effective at sterilising
equipment, autoclaves must
maintain a temperature of at
least 121°C for 30 minutes, with a
pressure of at least 205 kilopascals.
In a field test in Mumbai,
India, the researchers set up a
prototype and showed that it
could generate steam at 128°C
and 250kPa. They estimate that
it generates 260 watts of power.
When exposed to sunlight, the
solar heater took about 10 minutes
to heat water to the temperature
and pressure needed for the
autoclave (Joule, doi.org/fjpz). DLpeople with and without hearing
impairments, says Shoushtarian.
Earlier research shows that people
with tinnitus have less activity
in the cuneus, a brain region
involved in visual processing.
The people with tinnitus were
asked to rate how bad it was. These
results were correlated with the
patterns of brain activity based
on their fNIRS signals.
The team found that people
with more severe tinnitus had
higher levels of background
connectivity between certain
brain regions. In those with louder
tinnitus, brain responses to both
visual and auditory stimuli were
reduced, possibly because the
background neural activity with
tinnitus affects the brain’s ability
to respond (PLoS One, doi.org/fjqz).
The researchers then trained
an algorithm on the fNIRS and
tinnitus severity results. The AI’s
ability to objectively distinguish
between mild and severe tinnitus
may help to improve treatment,
says Shoushtarian. Donna LuKE
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