Research Highlights

Our pick of the latest scientific literature

  • Volume 571
  • Issue 7764
A thermographic image of a patterned ITO glass slide with a bolometric camera

Heated glass that has been etched with letters is imaged using a standard method for measuring temperature from a distance. A new, more sensitive version of the method can detect minute temperature changes. Credit: Sergii Yakunin/Bogdan Benin

Materials science

Glowing crystals help to measure temperatures from afar

New crystalline materials aid in the detection of tiny temperature shifts in a target object.

Crystals that detect temperature changes of just a fraction of a degree could form part of a ‘remote thermometer’ that gauges an object’s warmth from a distance.

For remote thermography, objects are coated with a substance that emits light when excited by a laser or other source. The length of the light emission, which is recorded by video, depends on the object’s temperature. But light-emitting substances now in use are sensitive to changes of only about 1 °C, and detectors to record these emissions are bulky and expensive.

Sergii Yakunin and Maksym Kovalenko at the Swiss Federal Institute of Technology in Zurich and their colleagues made light-emitting substances from crystalline materials called perovskites. The team’s perovskites, which contain tin and one element from the halogen family, are sensitive to temperature changes as small as 0.01 °C.

The team recorded high-quality videos of these crystals in action using a prototype camera similar to those that capture players’ 3D movements in motion-based video games. The crystals could be used to gauge the temperature of living cells.

Sargassum algae off Big Pine Key in the lower Florida Keys

The ‘great Atlantic Sargassum belt’ is a monstrous seaweed patch that stretches from the Gulf of Mexico (above, near the Florida Keys) to West Africa. Credit: Brian Lapointe/Florida Atlantic University

Ecology

Huge algal mat spanning an ocean is visible from space

Deforestation in the Amazon has helped to fuel the growth of a seaweed blanket that exceeded 20 million tonnes in 2018.

The world’s largest seaweed bloom stretches from West Africa to the Gulf of Mexico, an analysis of satellite data has found.

Two species of brown seaweed, Sargassum fluitans and Sargassum natans, are common in the Gulf of Mexico and the Sargasso Sea, which takes its name from the algae. But in 2011, a giant Sargassum bloom was spotted blanketing the central Atlantic Ocean.

Chuanmin Hu at the University of South Florida St. Petersburg and his colleagues scrutinized satellite data to track Sargassum blooms. They found a recurring belt of seaweed that, at its maximum in 2018, extended over a distance of more than 8,850 kilometres and had a biomass of more than 20 million tonnes.

The seasonal blooms seemed to be linked to two key factors: the upward surge of water from deep levels of the ocean off the coast of West Africa in winter, and a spring and summer influx of nutrients from the Amazon River — fuelled, in part, by deforestation and fertilization.

Fig. 4, panel showing the spleen of HIV-infected mice treated with CRISPR

Immune cells (brown) called CD4+ T cells are scarcer in the spleen of an untreated HIV-infected mouse (left) than in that of a mouse treated with antiretrovirals and CRISPR gene editing (right). Credit: Kamel Khalili

Medical research

CRISPR helps to rid mice of HIV

Gene-editing tool joins forces with antiretroviral drugs to drive HIV from its sanctuaries.

A regimen that includes CRISPR gene editing has eliminated HIV from the bodies of mice infected with the virus.

Antiretroviral drugs, which slow replication of HIV, have revolutionized AIDS treatment. But the drugs do not eliminate the virus from the body, and people who are infected must take the treatment for the rest of their lives.

Kamel Khalili at Temple University in Philadelphia, Pennsylvania, Howard Gendelman at the University of Nebraska Medical Center in Omaha and their colleagues treated HIV-infected mice with beefed-up antiretrovirals that suppress the virus longer than previous formulations. Special formulation meant that the drugs were released slowly into areas where HIV is known to lie latent. This dramatically reduced viral levels.

The scientists then injected 23 of the treated mice with a version of the CRISPR–Cas9 gene-editing system that was designed to snip HIV out of the genome. The virus eventually rebounded in 14 of the 23 mice, but remained undetectable in the other 9 even 8 weeks after treatment ended. Gene editing was able to eliminate HIV only after the drugs had suppressed the virus.

Artist's impression of the Gaia spacecraft, with the Milky Way in the background

Data from the Gaia spacecraft (artist’s rendering) helped to identify stars that survived a runaway nuclear reaction in their cores. Credit: ESA/ATG/ESO/S.Brunier

Astronomy and astrophysics

Three zombie stars on the run

Stars moving at high velocity seem to have managed to live on after cataclysm.

Astronomers have discovered three peculiar runaway stars that have apparently survived cataclysmic explosions at their cores.

A white dwarf is an ageing star that has burned through its original fuel. Under certain conditions, a white dwarf’s burnt-out core re-ignites; the core’s subsequent explosion is known as a supernova. Some stars are thought to survive these explosions to become so-called zombie stars.

To find potential zombies, Roberto Raddi at Friedrich Alexander University Erlangen–Nuremberg in Bamberg, Germany, and his colleagues searched for high-velocity objects that could have been propelled by explosions. The team mined data from sources including the European Space Agency's Gaia space telescope.

The researchers identified three stars that have unusually low masses for white dwarfs and atmospheres that are made mostly of neon and oxygen. These traits are markers of a relatively weak explosion that failed to blow its star completely to smithereens.

The authors propose that these three stars — along with a similar star found in 2017 — are the first known members of a new class of star.

Excavation of the Philistine Cemetery at Ashkelon.

Skeletons excavated from a cemetery (above) in ancient Ashkelon helped to trace the genetic history of the Philistines. Credit: Melissa Aja/Leon Levy Expedition to Ashkelon

Genomics

Ancient DNA reveals the roots of the Biblical Philistines

Bones found in the Philistine city of Ashkelon and dating to the twelfth century bc hint at European heritage.

The Philistines appear repeatedly in the Bible, but their origins have long been mysterious. Now genetic evidence suggests that this ancient people trace some of their ancestry west all the way to Europe.

Choongwon Jeong and Johannes Krause at the Max Planck Institute for the Science of Human History in Jena, Germany, and their colleagues analysed the DNA of ten ancient people whose bones were found in Ashkelon, a Philistine city located in modern-day Israel. The DNA suggests an influx of people of European heritage into Ashkelon in the twelfth century bc. The individuals' DNA shows similarities to that of ancient Cretans, but the team warns that it is impossible to specify the immigrants’ homeland because of the limited number of ancient genomes available for study.

Ashkelon skeletons dated to the tenth and ninth centuries bc bear almost no trace of European heritage, suggesting that the immigrants had no lasting genetic legacy.

Composite image of Cat image stored in metabolites and original artwork of Cat Killing a Serpent

A painting of a cat (right) was stored in digital form in chemical spots, which could be ‘read’ to reconstruct the image (left). Credit: Left:Eamonn Kennedy/Chris Arcadia/Brown University Right:Charles K. Wilkinson/Rogers Fund

Information technology

A ‘molecular thumb drive’ stores big files in small droplets

Information is encoded in spots made of assorted substances.

Droplets of small molecules such as amino acids and sugars hold promise as a highly efficient data-storage system.

To cope with the breakneck pace of digital-data generation, researchers have eyed DNA-based storage systems, which might store information more densely than traditional semiconductor chips. But droplets of even smaller molecules offer another option, according to work by Jacob Rosenstein and his colleagues at Brown University in Providence, Rhode Island.

The researchers fed a digital image file — coded as a pattern of ones and zeroes — to a liquid-spraying robot, which translated this pattern onto a steel plate as a grid of droplets containing mixtures of these molecules. Within each droplet, the addition or exclusion of each substance represented a one or zero, respectively, from the original image file. Once the droplets dried, an instrument recovered the image’s digital code of ones and zeroes by analysing the chemicals at each of the thousands of positions in the grid.

The researchers encoded and retrieved images up to several kilobytes in size.

A traffic policeman on duty in the snow, outside Horseguards in Whitehall, 1968.

Historical measurements of British snowfall (pictured, London in 1968) helped to reveal glitches in a key meteorological data series. Credit: Peter King/Getty

Climate sciences

Biased data undermine an iconic weather record

Flaws are revealed in a highly cited database that dates back more than two centuries.

Scientists have identified biased data in an iconic meteorological record, and are now challenging conclusions about long-term precipitation trends in England, Wales and possibly other regions.

The England and Wales Precipitation (EWP) series is a continuous monthly record of British snow and rainfall, stretching back to 1766. For decades, climate scientists have used this record — one of the longest-running available — to examine precipitation and atmospheric-circulation patterns in northwest Europe.

Conor Murphy at Maynooth University, Ireland, and his colleagues drew on independent data, including long-term measurements of British snowfall, to reconstruct the record’s early portion. Their reconstruction showed that the EWP underestimated winter precipitation before 1870, whereas summer rainfall was overestimated before 1820. As a result, the widely accepted conclusion that winters have become wetter and summers dryer since 1766 appears to be an artefact.

Scientists should exercise caution in using early EWP data and when drawing conclusions from other multicentury precipitation datasets, the authors say.

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