16 | New Scientist | 14 September 2019Animal behaviourClosing in on true
size of protonsWE AREN’T sure what the radius
of the proton is but a new way of
measuring it is helping.
Until 2010, we were fairly sure
about the proton’s size. We had
measured it using hydrogen
atoms made of one proton and an
electron. Then, a measurement
using muonic hydrogen – in which
the electron is replaced by another
particle called a muon – found a
value 4 per cent lower.Single head injury
can spark declineONE major blow to the head is
enough to trigger progressive
brain deterioration and long-term
cognitive decline in some people.
We already know that repeated
knocks to the head – like those
sustained in boxing and American
football – can lead to personality
changes, cognitive problems and
depression years later. This
condition, known as chronic
traumatic encephalopathy (CTE),
is associated with gradual build-up
of a protein called tau in the brain.
David Sharp at Imperial College
London and his team wondered if
similar changes can occur after
just one bad head injury.
To find out, they scanned the
brains of 21 men and women who
had a single major head injury
18 to 51 years ago in a car accident,
assault or fall. They all experienced
severe initial symptoms like loss
of consciousness for more thanNeuroscience PhysicsYOU can often tell where a
person comes from when they
speak. The same thing seems to
apply to humpback whales: their
songs can reveal their origin.
Ellen Garland at the University of
St Andrews in the UK and her team
made the discovery by recording the
songs of humpback whales passing
near the Kermadec Islands in the
South Pacific. They also recorded
whale songs at spots where they
gather to feed and breed across the
western and central South Pacific,
and off east and west Australia.
The team broke down each song
into units, like notes, that build
together to make a phrase, and
several phrases that repeat to form
a theme. A few themes are sung in a
set order to form a song. They found
three song types from 52 whales.
Song type 1 was dominant in thecentral Pacific, including the Cook
Islands and French Polynesia. Song
type 2 was most common in the
west, including New Caledonia,
Tonga and Niue. And song type 3
was only recorded in the waters
near eastern Australia.
Then the researchers compared
these songs with those of the
whales near the Kermadec Islands,
a migratory stopover. Based on the
percentage of similarity between
recordings, the team could pinpoint
where the whales at the Kermadec
Islands originated.
These findings were confirmed
with genetic and photographic
identification of the singing whales.
The team concluded most of the
Kermadec whales came from New
Caledonia, Niue and the Cook
Islands (Royal Society Open Science,
doi.org/c96d). Chelsea WhyteSong of the wandering
whale betrays its origins
Now Eric Hessels at York
University in Canada and his
team have developed a way to
measure the proton’s radius by
sending hydrogen atoms through
two sets of radio waves with
slightly different frequencies. This
excited some of the atoms into a
higher energy state. By measuring
how many atoms remained in the
lower energy state, the researchers
could calculate the proton’s radius.
The result matched that from
the muonic hydrogen, supporting
the idea that the proton is smaller
than we thought before 2010, at
around 0.83 femtometres, or
slightly less than one million-
billionth of a metre (Science,
doi.org/c96c).
“More and more measurements
seem to pile up at the smaller
radius now, so maybe this puzzle
will diffuse away,” says Thomas
Udem at the Max Planck Institute
of Quantum Optics in Germany.
Other experiments are under way
to provide further evidence.
Leah Crane30 minutes. Many later developed
problems with thinking, memory
and motivation. The scans showed
that 15 of them have unusually
high levels of tau in their brains,
particularly in the outer layers.
That may be because these layers
are most vulnerable to external
impacts (Science Translational
Medicine, doi.org/c96b).
High levels of tau have also
been found in the outer brain
layers of former athletes with
CTE, particularly in those who
have had the most head blows.
This is consistent with the idea
that brain deterioration can come
from either several relatively
minor brain injuries or from a
single severe one, says the team.
Both types of head injury
probably damage brain structures
called microtubules that are
stabilised by tau proteins, say the
researchers. This, in turn, could
make the tau proteins turn rogue
and start forming large tangled
clumps that gradually harm the
rest of the brain. Alice KleinTONY WU/NATUREPL.COM
LAGUNA DESIGN/SCIENCE PHOTO LIBRARYNews In brief