New Scientist - USA (2020-07-25)

25 July 2020 | New Scientist | 19

Physics

Zoology Vaccines

Beetle cams stream

live bug’s eye view

Tiny cameras fixed to the

backs of beetles can stream

an hour of live footage to

a smartphone app. They

were tested on pinacate

beetles (one pictured)

and death-feigning

beetles (Science Robotics,

doi. org/ gg4295).

Siberia feels the

heat because of us

The record-breaking

heatwave that has

baked Siberia for the

past six months was made

at least 600 times more

likely because of climate

change. Researchers

at the World Weather

Attribution initiative say it

is “effectively impossible”

for it to have occurred

without the warming

driven by human activities.

Underground lasers

clock Earth’s spin

Huge lasers set 15 metres

beneath Earth’s surface are

being used to measure the

planet’s spin with the most

precision ever. The effects

of Earth’s motion slightly

move mirrors reflecting

the lasers, which scientists

use to understand how

the planet rotates (Physical

Review Letters, doi.org/

d4bz). This could help

make GPS navigation

more accurate.

Is this the lightest

mirror of them all?

MIRRORS are usually created from

the flat surfaces of metal or coated

glass, but now they can be made

from a few hundred atoms.

Jun Rui at the Max Planck

Institute for Quantum Optics in

Germany and his colleagues have

made a mirror from a single layer

of rubidium atoms. They believe it

is the lightest mirror ever created.

To make it, the team first cooled

several hundred atoms of the

isotope rubidium-87 using a

SEA turtles are famed for their

ability to navigate across open

oceans. Now we have a better idea

of how they do it, thanks to a study

that reveals they often get lost.

“We were impressed that they

are able to find small islands,”

says Nicole Esteban at Swansea

University in the UK. “But their

navigation is crude.”

Green sea turtles spend most

of their lives in one area, feeding on

seagrass in shallow waters. Every

few years, they migrate to breeding

areas that can be thousands of

kilometres away, spending a few

months there before returning.

During four migrations, Esteban

and her colleagues put GPS trackers

on 33 female green sea turtles after

they had nested on the Indian Ocean

island of Diego Garcia. As the turtles

can’t feed in the open ocean, their

likely aim is to head straight home.

Few managed it. Turtles returning

to remote atolls and islands often

missed their target and ended up

swimming far further than needed.

The tracking suggests that they

navigate long distances using

a basic mental map and a crude

sense of compass orientation. They

set off in roughly the right direction

and eventually realise if they have

gone too far (Current Biology,

doi. org/d36d). Michael Le Page

process known as laser cooling.

“Imagine atoms as basketballs

and the photons as ping-pong

balls,” says Rui. By directing

enough photons at the rubidium,

the tiny force of each one can

collectively slow down the atoms.

A second stage called

evaporative cooling reduced the

atoms’ temperature to around

10 nanokelvin. The researchers

then applied a precise magnetic

field in one direction to isolate

a single layer of atoms (Nature,

doi. org/gg45v9).

When atoms are randomly

scattered in space they each

Secrets of a US civil

war-era smallpox kit

STRAINS of viruses used for

smallpox vaccines in the US

during the civil war have been

identified and their genomes

reconstructed.

Smallpox, caused by the variola

virus, killed about 30 per cent of

those it infected. It was officially

eradicated in 1980 after concerted

global vaccination efforts.

Early protective practices

against it involved infecting

people with related viruses such as

vaccinia to induce a milder case of

disease that would inoculate them

against variola. This was usually

done by applying some infected

pus or scabs to a cut in the skin.

While at McMaster University

in Canada, Ana Duggan and her

colleagues analysed genetic

material collected from five

US civil war-era vaccination

kits that included tin boxes

with scab material.

All five of the viruses identified

were strains of vaccinia. None

of the viral genetic material was

intact, so it wasn’t infectious.

The team then pieced together

the viral fragments like a jigsaw

puzzle, with the aid of a computer

algorithm as well as the genetic

sequence of an intact vaccinia

virus as a reference (Genome

Biology, doi.org/d4bx). DL

interact with light independently,

says Rui. But in the ordered lattice

in the isolated layer, interactions

between the atoms change their

collective optical properties.

“Because of the close spacing in

between the atoms, they will not

emit light independently, but

instead they can crosstalk with

each other,” says Rui. The result

is a two-dimensional plane that

reflects light shone on it.

Further exploration of the

light-mediated interactions

between atoms may lead to

advances in quantum optics,

says Rui. DL

Turtles often get hopelessly

lost on long ocean journeys

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Really brief

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