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Can life survive a star’s death? Webb telescope can reveal the answer

When stars like our sun die, all that remains is an exposed core — a white dwarf. A planet orbiting a white dwarf presents a promising opportunity to determine if life can survive the death of its star, according to Cornell University researchers.

In a study published in the Astrophysical Journal Letters, they show how NASA’s upcoming James Webb Space Telescope could find signatures of life on Earth-like planets orbiting white dwarfs.

A planet orbiting a small star produces strong atmospheric signals when it passes in front, or “transits,” its host star. White dwarfs push this to the extreme: They are 100 times smaller than our sun, almost as small as Earth, affording astronomers a rare opportunity to characterize rocky planets.

“If rocky planets exist around white dwarfs, we could spot signs of life on them in the next few years,” said corresponding author Lisa Kaltenegger, associate professor of astronomy in the College of Arts and Sciences and director of the Carl Sagan Institute.

Co-lead author Ryan MacDonald, a research associate at the institute, said the James Webb Space Telescope, scheduled to launch in October 2021, is uniquely placed to find signatures of life on rocky exoplanets.

“When observing Earth-like planets orbiting white dwarfs, the James Webb Space Telescope can detect water and carbon dioxide within a matter of hours,” MacDonald said. “Two days of observing time with this powerful telescope would allow the discovery of biosignature gases, such as ozone and methane.”

The discovery of the first transiting giant planet orbiting a white dwarf (WD 1856+534b), announced in a separate paper — led by co-author Andrew Vanderburg, assistant professor at the University of Wisconsin, Madison — proves the existence of planets around white dwarfs. Kaltenegger is a co-author on this paper, as well.

This planet is a gas giant and therefore not able to sustain life. But its existence suggests that smaller rocky planets, which could sustain life, could also exist in the habitable zones of white dwarfs.

“We know now that giant planets can exist around white dwarfs, and evidence stretches back over 100 years showing rocky material polluting light from white dwarfs. There are certainly small rocks in white dwarf systems,” MacDonald said. “It’s a logical leap to imagine a rocky planet like the Earth orbiting a white dwarf.”

The researchers combined state-of-the-art analysis techniques routinely used to detect gases in giant exoplanet atmospheres with the Hubble Space Telescope with model atmospheres of white dwarf planets from previous Cornell research.

NASA’s Transiting Exoplanet Survey Satellite is now looking for such rocky planets around white dwarfs. If and when one of these worlds is found, Kaltenegger and her team have developed the models and tools to identify signs of life in the planet’s atmosphere. The Webb telescope could soon begin this search.

The implications of finding signatures of life on a planet orbiting a white dwarf are profound, Kaltenegger said. Most stars, including our sun, will one day end up as white dwarfs.

“What if the death of the star is not the end for life?” she said. “Could life go on, even once our sun has died? Signs of life on planets orbiting white dwarfs would not only show the incredible tenacity of life, but perhaps also a glimpse into our future.”

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Materials provided by Cornell University. Original written by Kate Blackwood. Note: Content may be edited for style and length.

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Study reveals how long COVID-19 remains infectious on cardboard, metal and plastic

The virus that causes COVID-19 remains for several hours to days on surfaces and in aerosols, a new study published in the New England Journal of Medicine found.

The study suggests that people may acquire the coronavirus through the air and after touching contaminated objects. Scientists discovered the virus is detectable for up to three hours in aerosols, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

“This virus is quite transmissible through relatively casual contact, making this pathogen very hard to contain,” said James Lloyd-Smith, a co-author of the study and a UCLA professor of ecology and evolutionary biology. “If you’re touching items that someone else has recently handled, be aware they could be contaminated and wash your hands.”

The study attempted to mimic the virus being deposited onto everyday surfaces in a household or hospital setting by an infected person through coughing or touching objects, for example. The scientists then investigated how long the virus remained infectious on these surfaces.

The study’s authors are from UCLA, the National Institutes of Health’s National Institute of Allergy and Infectious Diseases, the Centers for Disease Control and Prevention, and Princeton University. They include Amandine Gamble, a UCLA postdoctoral researcher in Lloyd-Smith’s laboratory.

In February, Lloyd-Smith and colleagues reported in the journal eLife that screening travelers for COVID-19 is not very effective. People infected with the virus — officially named SARS-CoV-2 — may be spreading the virus without knowing they have it or before symptoms appear. Lloyd-Smith said the biology and epidemiology of the virus make infection extremely difficult to detect in its early stages because the majority of cases show no symptoms for five days or longer after exposure.

“Many people won’t have developed symptoms yet,” Lloyd-Smith said. “Based on our earlier analysis of flu pandemic data, many people may not choose to disclose if they do know.”

The new study supports guidance from public health professionals to slow the spread of COVID-19:

  • Avoid close contact with people who are sick.
  • Avoid touching your eyes, nose and mouth.
  • Stay home when you are sick.
  • Cover coughs or sneezes with a tissue, and dispose of the tissue in the trash.
  • Clean and disinfect frequently touched objects and surfaces using a household cleaning spray or wipe.

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Materials provided by University of California – Los Angeles. Note: Content may be edited for style and length.

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With this new alpha-gel, the cream of all skin creams could be here

A layer of lipids covers our skin, and with its help our skin retains moisture and remains healthy. In the lipid layer, a compound called ceramide forms a “lamellar gel” with cholesterol, fatty acids, and water. Lamellar gels are mixtures that are thick, do not flow easily, and can hold large amounts of water. Natural ceramide is therefore an important factor for water retention in our skin. A type of lamellar gel, called the “α-gel,” can be formulated by mixing compounds called surfactants with a fatty alcohol and water. As you may have guessed by this explanation, α-gels are widely used in skincare products such as skin creams.

In a new study published in Colloids and Surfaces A, scientists from Tokyo University of Science and Miyoshi Oil and Fat Co. Ltd., Japan, led by Dr Kenichi Sakai, synthesized an α-gel using an oleic acid-based surfactant, which can potentially be used in skincare products. This is a surfactant they had previously developed and is structurally similar to natural ceramide (both are amphiphiles with two tails). “I was interested in whether α-gels could be prepared using gemini surfactants (two-tailed and two-headed surfactants), and in what their structural and physical properties would be,” Dr Sakai says.

Once the α-gel was ready, Dr Sakai and his team used a technique called small- and wide-angle X-ray scattering (SWAXS), another technique called nuclear magnetic resonance (NMR) spectroscopy, and an optical microscope to confirm its characteristics. For this, they prepared several mixtures containing different molar ratios of the oleic acid-based surfactant, water, and 1-tetradecanol (a fatty alcohol). The findings were, indeed, satisfactory.

SWAXS measurements revealed the typical lamellar or sheet-like structure of α-gels: layers of molecules stacked over each other such that a vertical cross-section has molecules aligned in straight lines and a horizontal cross-section could appear hexagonal. This means that the prepared mixture formed an α-gel. The structure remained highly ordered even when 90% of the mixture by weight was water.

When the scientists further analyzed the SWAXS measurements, they found that increasing the molar content of the fatty alcohol in the mixture increases the space between the molecular “bilayers” in the stacked-structure of the α-gel. Bilayers are a pair of molecular layers in which the tail-ends of both layers point to each other. A property of α-gels is that water fills the space between these bilayers. In this case, the scientists think that the increase in the space between the bilayers must be because more water filled it.

NMR spectroscopy then showed that fatty alcohol molar content increase also caused a decrease in the movement of protons within the molecular bilayers, which is in keeping with characteristics lamellar gels are known to have.

Dr Sakai and his team were also aware that α-gels systems are known to demonstrate “shear thinning,” i.e., when they are pressed and dragged against a surface, they spread out evenly as a dollop of paint would do when applied to a wall with a brush. All mixtures in the study showed shear thinning, so the scientists looked through an optical microscope to find out why. They saw a progressive and specific change in the structure of the α-gel with an increase in fatty alcohol content. Reports of previous studies had told them that this specific structural change causes α-gels to become as thick as is necessary for shear thinning.

Thus, overall, the prepared α-gel’s ability to hold water and spread out evenly over surfaces makes it suitable for skincare products such as skin creams. What’s more, the oleic acid-based surfactant is readily soluble in water, and so its production is easier and possible at low energy-costs. Dr Sakai explains, “It is an environment-friendly functional organic material because even when it is added in small amounts, it exhibits surface chemical functions not inferior to those of conventional surfactants.”

So, cross your fingers; the perfect skin cream may not be long!

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Materials provided by Tokyo University of Science. Note: Content may be edited for style and length.

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Satellite-based estimates of reduced deforestation in protected areas needed

In the context of progressing towards new targets for a post-2020 Global Biodiversity Framework, the debate remains on whether the emphasis should be on protected area coverage or protected area effectiveness. “It is worrying that we still know so little about how effective protected areas are, especially in relation to management inputs” says Dr. Johanna Eklund from the University of Helsinki.

A recent study she led compared common indicators of Protected Area Management Effectiveness, used by for example the Global Environmental Facility, WWF and other conservation actors, to satellite-based estimates of reduced deforestation in Madagascar. The international team found that overall protected areas were reducing deforestation within their borders, although variation in effectiveness existed, highlighting also clear needs for improvements. The variation, however, was not explained by management input assessments conducted following common global protocols and widely used by funders and non-governmental organizations.

“Self-reports of management effectiveness were generally good, with rather small differences between areas. Such lack of resolution may hinder the use of management-effectiveness indicators when identifying priorities for management investments at national level” says Dr Mar Cabeza from the University of Helsinki and co-author of the new study.

Nonetheless, the results, which were recently published in the scientific journal Conservation Science and Practice, also carry some good news: approximately half of the protected areas studied showed no deforestation at all inside their borders, and only three of the areas showed very high levels of deforestation. What is more, they also showed that 29 out of the 36 studied PAs had an impact in mitigating deforestation within their borders, i.e. without protecting these areas, the situation would have been much gloomier.

“It is inspiring to be able to report that conservation actions matter,” says Dr Eklund. “Too much doom and gloom can passivate even the most enthusiastic of us; leading to despair and the feeling that both climate change and biodiversity loss are lost causes.”

Not just paper parks

Tropical forests are of utmost importance for both biodiversity and climate change mitigation, yet under increased pressures to clear land for agriculture and production. One of the most widely used policy tools currently available to avert habitat loss and deforestation is the establishment of protected areas. However, previous research has highlighted that many protected areas are so-called paper parks, i.e. established on paper but lacking active management to ensure they have the capacity to mitigate threats.

This is why it is important to investigate how protected areas perform after they have been established. Why do some protected areas seem to be effective in avoiding high pressures of logging, whereas others cannot mitigate them?

Evaluating conservation actions

To find out the impact a conservation intervention or programme has had, there is a need to evaluate the outcomes compared to what the situation would have been had the intervention not taken place. “A bit similar as in medical science,” says Dr Eklund, “where the effect of a pill or treatment is evaluated against a control group. The challenge in conservation science is that we often lack a suitable baseline to compare to; many protected areas have been established a long time ago and in areas of lower pressures, in order to avoid land conflicts in more productive landscapes. This needs to be accounted for in studies evaluating conservation effect.”

Does management matter and how?

The team compiled unique data on management inputs and how this changed over time. They had access to information on how adequate levels of personnel and funding had been, how well different monitoring and enforcement strategies had been implemented, and how the collaboration with local communities and other stakeholders had developed. Surprisingly enough though, protected areas with higher management scores did not perform better in terms of avoiding deforestation. The assessment was only able to capture an extreme case where poor management was linked to a protected area showing increased deforestation, that is, even higher levels of deforestation than predicted. The authors suggest that one explanation for the general lack of correlation may be that management levels of the PAs in Madagascar were already at basic to sound levels and located in areas with low rates of forest loss, and therefore this set of PAs provides little variation with which to explore the effect of different levels of management. Moreover, previous studies have shown that local managers identify weak governance at the national level as an obstacle for effective management, suggesting the broader sociopolitical context might matter more than local management.

Policy implications

The results have policy implications both for Madagascar and internationally. The local conservation sector in Madagascar can use the results to prioritize key areas for development and target limited conservation resources to areas where they might make the biggest difference. The results are also of relevance for the post-2020 targets of the Convention on Biological Diversity. Dr Eklund hopes that different measures of effectiveness, not merely an increase in protected area coverage, would be better incorporated into the wording of the new targets. “Continued efforts to carry out quantitative impact evaluations of protected area effectiveness, and collection of management effectiveness data, are needed, as our study shows that they can complement each other in displaying different facets of how PAs perform,” concludes Dr Eklund.

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