16 | New Scientist | 24 August 2019EnvironmentPowered shorts help
you to walk and runSPORTSWEAR is getting a robotic
upgrade. An exosuit worn like a
pair of shorts makes walking and
running more energy efficient.
Philippe Malcolm at the
University of Nebraska Omaha
and his team developed the suit
(pictured), which reduces energy
use when walking by 9 per cent
and when running by 4 per cent.
This exosuit isn’t the first to cut
the energy spent moving – othersGems point to chunk
of original Earth rockA UNIQUE haul of diamonds that
formed very deep in our planet
has been found in Brazil. They
contain evidence that suggests a
piece of primordial Earth rock has
survived more than 4 billion years
of violent geological activity.
Several diamonds found in
the Juína area of Brazil were
analysed by Suzette Timmerman
at the Australian National
University and her colleagues.
They found high levels of an
ancient helium isotope called
helium-3 that was incorporated
into Earth’s first rocks.
This suggests the “super-deep”
diamonds, which are themselves
thought to be less than
500 million years old, formed in
or above a remnant of the first
rocks that formed on Earth. As
the diamonds took shape, they
encapsulated some of the ancient
helium-3 that is slowly diffusingGeology^ TechnologyA LACK of water vapour in the
atmosphere has caused a global
decline in plant growth rates over
the past two decades. Growth
rates fell in 59 per cent of all
vegetated areas.
Wenping Yuan at Sun Yat-sen
University in Zhuhai, China, and
his colleagues made the discovery
using four global climate data sets
and satellite images. They found
the decline in plant growth is
correlated with a vapour pressure
deficit in the atmosphere, which
has increased sharply in many
areas since the late 1990s.
Vapour pressure deficit (VPD) is
the difference between the pressure
exerted by water vapour if the
air were fully saturated and the
pressure it actually exerts. When
this deficit increases, the pores on
leaves (pictured) that let in carbondioxide close up, resulting in lower
photosynthesis rates.
Climate change may be to blame,
says Yuan. There has been a fall in
wind speeds over oceans, which
means water vapour doesn’t blow
over land as readily. Warming
also has a role. As temperatures
increase, the upper limit on the
amount of water vapour the
atmosphere can hold also rises,
adding to the VPD, he says.
When the researchers analysed
satellite images, they found a
corresponding drop in the growth
rates of global vegetation and leaf
coverage since 1998. There was
also a decrease in average tree
ring width, a measure of growth,
at more than 100 of 171 sites.
The team projects that VPD will
continue to rise (Science Advances,
doi.org/gf6gm5). Donna LuPlant growth suffers widely
as atmospheric changes bite
have been able to make either
walking or running alone more
energy efficient – but Malcolm
and his colleagues say their device
is the first that can do both.
The exosuit weighs 5 kilograms
and consists of two fabric wraps
around the thighs connected to a
fabric waist-belt. Cables that run
from the belt pull on the thigh
wraps to assist with movement.
The suit uses a sensor on
the torso to detect whether the
wearer is walking or running,
while sensors on the thighs detect
changes in leg position. A motor
unit on the back of the suit
begins pulling a cable just before
a wearer’s front foot hits the
ground, aiding the body and
reducing the amount of energy
spent to generate the same force.
Malcolm and his team tested
the suit on nine people on
treadmills. Each walked
450 metres over 5 minutes and
ran 750 metres over 5 minutes,
with the suit switched both on
and off (Science, doi.org/c9hm). DLupwards from this primordial
rock, says Timmerman. This
makes these diamonds unique
time capsules to study such rock.
The diamonds also contain
a mineral called breyite that is
formed at ultra-high pressures,
suggesting they originated about
410 to 660 kilometres down.
Normally, diamonds form less
than 230 km underground.
The gems were transported
by upwellings of hot rock and
volcanic eruptions about
93 million years ago, finally
ending up in the Juína mines
(Science, doi.org/c9hn).
The researchers are now hoping
to work out where the preserved
primordial rock is and its size.
Timmerman’s best guess is that
it is a very dense structure close
to Earth’s core.
It won’t be possible to access
the rock directly because it is
far too deep underground, but
further studies of super-deep
diamonds may help us to
understand it better. Alice KleinSTEFAN DILLER/SCIENCE PHOTO LIBRARY
W YSS INSTITUTE AT HARVARD UNIVERSITYNews In brief