A sensor too small to see sizes up force fields

Dancing ion allows for measurement of minuscule forces. Dancing ion allows for measurement of minuscule forces.


Why sea mammals loom large
Scientists have long puzzled over why marine mammals tend to be much larger than land mammals. An analysis of nearly 7,000 living and extinct species suggests that sea-going mammals grew big to keep warm.
William Gearty at Stanford University in California and his colleagues found that of the four groups of marine mammals in the oceans today, three have evolved an average mass of about 500 kilograms: sea cows; seals and their relatives; and toothed whales such as dolphins. By contrast, the average mass of their ancestral land-dwelling groups varied over 1-100 kilograms. Marine mammals also show less variation from the average mass than land mammals do, suggesting that aquatic life is a greater constraint on body size. GRIFFITH  The team administered the experimental therapy to mice using a nasal spray. In animals with late-stage brain disease, treatment greatly lowered viral concentrations in the brain and increased survival rates compared with untreated animals. Survivors also developed long-term protection against future infection.

APPLIED PHYSICS
Lonely ion feels the force A single ion can provide a super-sensitive way of determining the strength of an electric field.
Scientists have turned to single-atom sensors to measure minute electromagnetic forces. A team led by Erik Streed at Griffith University in Brisbane, Australia, trapped a glowing ytterbium ion with an electric field, then displaced the ion with another electric field. The researchers used a camera and magnifying lens (pictured) to measure the displacement of the ion in three dimensions.
The team was able to detect movements to an accuracy of several nanometres, corresponding to forces as small as attonewtons (1 attonewton is 10 −18 newtons). The researchers say their method could be expanded to observe multiple ions simultaneously, which would allow the method to map the contours of a force field.

Long worm has strong poison
A slimy worm that can stretch to 50 metres long may seem nightmarish enough, but experiments reveal that the bootlace worm has another formidable feature: a potent nerve toxin.
The invertebrate (Lineus longissimus), which lives on the sea floor and is thought to be the longest animal on Earth, squirts mucus when disturbed. Ulf Göransson at Uppsala University in Sweden and his colleagues analysed the mucus and isolated a peptide that they named nemertide α-1. When the researchers injected low doses of the peptide into green crabs (Carcinus maenas) and juvenile Dubia cockroaches (Blaptica dubia), the animals became paralysed and died.
The team found that the peptide disrupts nerve-cell activity in roaches and other invertebrate pests but is much less potent when applied to mammalian nerve cells. Along with related peptides from the bootlace worm, nemertide α-1 may prove to be a valuable insecticide, the authors say.
Sci. Rep. 8, 4596 (2018) period. From the second cold spell, the site yielded animal bones that had been deliberately mixed with larger quantities of woodworking debris. Separate research suggests that other European hunter-gatherers possibly succumbed to abrupt climate change, but the Star Carr people were resilient enough to survive, the authors say. Nature Ecol. Evol. http://dx.doi. org/10.1038/s41559-018-0508-4 (2018) Small mammals lose heat quickly in water, and very large ocean-going animals find food less efficiently than smaller ones, leaving aquatic mammals a relatively narrow window of suitable body size. The largest whales might have escaped the latter of these constraints by turning to filter-feeding, the authors say.