Sloths’ sluggish secrets, glowing parasites and elusive dark matter
If time feels like it’s dragging its feet on a Friday afternoon, spare a thought for the sloth – its entire life is in slow motion. Learn more about these tree-dwellers, and a whole lot more, in Cosmos art director Robyn Adderly’s images of the week.
First atmospheric study of Earth-sized exoplanets
Using NASA's Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system, uncovering clues that increase the chances of habitability on two exoplanets.
They discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds. Those dense atmospheres act like a greenhouse, smothering any potential life.
Scaling new heights
Taken standing on the floor in the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center in Florida, this photograph shows the view looking up at four new work platforms, part of 10 work levels that will surround and provide access to the Space Launch System rocket and Orion spacecraft for Exploration Mission 1.
Most sensitive dark matter detector completes search
After a 20-month run, the Large Underground Xenon (LUX) dark matter experiment, which operates beneath a mile of rock at the Sanford Underground Research Facility in the Black Hills of South Dakota, has completed its silent search for the missing matter of the universe.
LUX scientific collaborators presented the results of the dark matter experiment, at this week's international dark matter conference in Sheffield, UK.
Read about the research results here: Latest search for dark matter draws a blank
Why sloths are so sluggish
The slow-motion lifestyle of tree sloths, according to a study in The American Naturalist, is the direct result of the animal's adaptation to its arboreal niche.
Tree sloths are among the most emblematic tree-dwelling mammals. But they are best known for their pokey demeanor rather than the fact that they spend the majority of their life in trees munching leaves.
Researchers found three-toed sloths expend as little as 460 kilojoules of energy a day – roughly the same energy found in a baked potato. It is the lowest measured energetic output for any mammal.
A diet of plant leaves has little nutritional value and the animal's gut size limits it to small amounts per day, so the animals need to find ways to make the most of their skimpy diet. For sloths, that means expending minimal amounts of energy through a reduced metabolic rate, dramatic regulation of body temperature and navigating the world in slow motion.
Trypanosome parasites cause sleeping sickness in Africa. If left untreated, the infection causes coma and eventually death.
A study published this week in PLOS Pathogens took a closer look at what happens after an infected tsetse fly transmits parasites into the skin of a mouse host.
The study used an animal model to observe the natural course of infection – an infected tsetse fly biting the ear of a mouse – and allowed easy visualisation of trypanosomes, because they were fluorescently tagged (pictured in blue).
By following the parasites over time, the researchers studied how they spread from the initial inoculation site and multiply in the mouse host. The study found only very few parasites are needed to successfully colonise the host.
Parasites mulitplying at the bite site created a reservoir from which they could be picked up by subsequent tsetse fly bites.