Astronomy
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On Mars, Life Could Be Hiding Under The Rocks
Living on Mars would be tough by any measure — so tough, that there's considerable debate about whether even the hardiest of microbes could survive. The atmosphere is thin, the surface is baked with radiation and the planet itself is mostly arid, dusty and wind-swept.
But there could be niches where life thrived in the distant past, when Mars had a thicker atmosphere and a wetter surface. So when Red Planet scientist Janice Bishop was invited to look at carbonate rocks in the Mojave Desert a few years ago, she immediately saw implications for Mars.
Bishop had already published a 2006 International Journal of Astrobiology paper calling iron oxides an "ultraviolet sunscreen" for ancient photosynthesis on Earth. The result of the newer study, published in 2011 in the same journal showed that the Mojave rocks collected also had iron oxide coatings, under which carbonates were hiding.
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But would this process be enough to save a Martian microbe today? Bishop says she believes there were microbes in the distant past, but in the arid Red Planet environment today, "It's kind of a stretch."
However, she added, other researchers think that life could persist in briny water environments on the planet, such as recurring slope lineae that occur seasonally in craters and other sloped locations on Mars.
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The Case Of Ceres’ Disappearing Volcanoes
In 2015, NASA’s Dawn spacecraft discovered a lone 4-km (2.5-mile) high mountain on the dwarf planet Ceres. Identified as a cryovolcano, which erupts ice and other volatiles instead of lava like a traditional volcano, Ahuna Mons was magnificent but alone on Ceres’ surface. Now, however, scientists say that Ceres may have been home to many more such cryovolcanoes in the past, which could have slowly disappeared and left Ahuna Mons as the only remaining feature of recent geologic activity.
Michael Sori of the Lunar and Planetary Laboratory at the University of Arizona in Tucson is the lead author of a new paper accepted for publication in the American Geophysical Union’s journal, Geophysical Research Letters. In recent a press release, Sori explains why Ahuna Mons is such a mystery, saying, “Imagine if there was just one volcano on all of Earth. That would be puzzling.” But Sori’s team has now proposed a possible solution to this exact puzzle, a process called viscous relaxation. If this process is truly at work on Ceres, then, “We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed,” Sori says.
Viscous relaxation refers to the flow of solids over time. On Earth, the best example of this process is the flow of glaciers, which are solid ice but move and flow slowly, given enough time. While viscous relaxation doesn’t apply to Earth’s volcanoes, which are made of rock, it could apply to cryovolcanoes, which are made of ice, just like glaciers. Sori’s team speculates that older cryovolcanoes have undergone such viscous relaxation over the past few millions or billions of years, possibly aided by Ceres’ close orbit to the sun. This would leave only the younger Ahuna Mons clearly visible on Ceres’ surface. Based on computer models of this process, and assuming that Ahuna Mons is composed of at least 40 percent water, Sori’s team estimates that this feature would flatten out at a rate of 10-50 meters (30-160 feet) every million years. But because Ahuna Mons is only 200 million years old at most, “it just hasn’t had time to deform,” Sori explains.
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Biology
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Fleeting Dead Zones Can Muck With Seafloor Life For Decades
Short bouts of suffocating conditions can desolate swaths of seafloor for decades, new research suggests. That devastation could spread in the future, as rising temperatures and agricultural runoff enlarge oxygen-poor dead zones in the world’s oceans.
Monitoring sections of the Black Sea, researchers discovered that even days-long periods of low oxygen drove out animals and altered microbial communities. Those ecosystem changes slow decomposition that normally recycles plant and animal matter back into the ecosystem after organisms die, resulting in more organic matter accumulating in seafloor sediments, [...].
Carbon is included among that organic matter. Over a long enough period of time, the increased carbon burial could help offset a small fraction of carbon emitted by human activities such as fossil fuel burning, says study coauthor Antje Boetius, a marine biologist at the Max Planck Institute for Marine Microbiology in Bremen, Germany. That silver lining comes at a cost, though. “It means your ecosystem is fully declining,” she says.
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Scientists have noticed increased carbon burial in hypoxic waters before. The mechanism behind that increase was unclear, though. Boetius and colleagues headed out to the Black Sea, the world’s largest oxygen-poor body of water, and studied sites along a 40-kilometer-long stretch of seafloor. (Military activities in the region following Russia’s annexation of Crimea limited where the researchers could study, Boetius says.) Some sites were always flush with oxygen, some occasionally suffered a few days of low oxygen, and others were permanently oxygen-free.
The ecological difference between the sites was stark. In oxygen-rich waters, animals such as fish and starfish flourished, and little organic matter was deposited on the seafloor. In areas with perpetually or sporadically low oxygen, the researchers reported that oxygen-dependent animals were nowhere to be seen, and organic matter burial rates were 50 percent higher.
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Status Profiling: Research Suggests Simply Wearing A Police Uniform
Changes The Way The Brain Processes Information
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"We all know that the police generally do an excellent job, but there has also been a great deal of public discourse about biased policing in North America over recent years," says Sukhvinder Obhi, an associate professor of Psychology, Neuroscience & Behaviour and senior author of the study, which was conducted with postdoctoral researcher Ciro Civile.
"We set out to explore whether the uniform itself might have an impact, independent of all other aspects of the police subculture, training or work experiences," he says.
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During one experiment, participants were asked to identify a simple shape on a computer screen and were distracted by images of white male faces, black male faces, individuals dressed in business suits and others dressed in hoodies. Researchers tracked and analyzed their reaction times to compare how long they were distracted by the various images.
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The differences, however, were revealed when participants were distracted by photos of individuals wearing hoodies. Reaction times slowed, indicating that the images of hoodies were attention-grabbing. Critically, this bias towards hoodies only occurred when participants were wearing the police-style garb.
"We know that clothing conveys meaning and that the hoodie has to some extent become a symbol of lower social standing and inner-city youth," says Obhi. "There is a stereotype out there that links hoodies with crime and violence, and this stereotype might be activated to a greater degree when donning the police style uniform. This may have contributed to the changes in attention that we observed. Given that attention shapes how we experience the world, attentional biases toward certain groups of people can be problematic."
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Chemistry
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A Matter Of Taste?
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We think of the tongue as the prime organ for tasting food and detecting nutrients.2 However, from a chemosensory receptor point of view, taste receptors are actually outnumbered by pain and other somatosensory receptors on the tongue. Linda Bartoshuk, a psychologist specialising in taste, has described the small bundles of taste buds on our tongues as being surrounded by large chalices of receptors that are fine-tuned to detect changes in heat energy, physical pressure and chemical irritants – including pain.
It is not unusual for animals to have an abundance of somatosensory receptors as a sort of protective shield or ‘sensory lighthouse’ to warn of environmental hazards. Understandably, we often mix up somatosensory stimulation with taste because they both occur on the tongue. For example, the heat of capsaicin from chillis and the pungent bite of non-volatile vanillylamides in ginger are detected on the tongue not by taste receptors, but by somatosensory receptors – a process referred to as chemesthesis. These receptors are proteins that form transient receptor potential (TRP) channels, which allow ions to flow into nerve cells and contribute to the multimodal signal. Pepparkakor, the Swedish version of gingerbread, contains biochemical extracts from spices that interact more with pain receptors than with those we use to detect simple sugars.
In the balance
It seems incongruous that deliciousness is connected to an assault on our mouth by biochemical plant extracts. Where’s the enjoyment in that? The answer is a psychophysical phenomenon known as mixture suppression:3 the muting of the intensity of individual stimuli when perceived in a mixture. Sugar in your coffee, salt and vinegar on your fish and chips, and cinnamon and clove in pepparkakor are all examples. Identifying these chemesthetic mixtures presents a challenge for food scientists and chefs – harmonious flavours are more difficult to describe than ‘off flavours’.
The ingredients containing chemesthetic agents come primarily from the plant kingdom, and are most prominent in herbs and spices. In pepparkakor, four major ingredients contribute: ginger, cinnamon, cloves and cardamom [...]. Each of these ingredients also contributes perceptible volatile compounds (aromas), some unique and some shared by their volatile profiles.
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So as you nibble on your next crumbly and pungent – but not too pungent – batch of gingerbread, consider the balance and harmony in flavour. Use your growing understanding of flavour balance to analyse other foods and understand their harmonious blend of often opposing or contradicting chemical stimuli. Consider how recipes, handed down over the years, forged by preferences and necessity, provide models for chefs and home cooks that describe how culinary techniques influence flavour balance and the hedonic quality of food. Or, alternatively, just enjoy the results.
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Ecology
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Wind Surpasses Hydroelectric As Top U.S. Renewable Energy Source
For decades, hydroelectric dams served as the United States’ top source of renewable energy. But last year, wind power took the top spot, according to a new report by the American Wind Energy Association, an industry trade group. It is now the fourth largest source of energy in the U.S., behind natural gas, coal, and nuclear.
Total hydroelectric generating capacity in the U.S. was 78,956 megawatts in 2015. Wind capacity reached 82,183 megawatts last year, more than triple what it was in 2008 and enough to power 24 million households, according to the report. The wind industry also supports 100,000-plus U.S. jobs, more than nuclear, natural gas, coal, or hydroelectric.
“American wind power is on track to double our output over the next five years, and supply 10 percent of U.S. electricity by 2020,” Tom Kiernan, CEO of the association, said in a statement. “Wind power isn’t a red or blue industry… Low-cost, homegrown wind energy is something we can all agree on.”
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Methane Levels Have Increased In Marcellus Shale Region Despite A Dip In Well Installation
Despite a slow down in the number of new natural gas wells in the Marcellus Shale region of Northeast Pennsylvania, new research led by Drexel University finds that atmospheric methane levels in the area are still increasing.
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Since the first shale gas wells were drilled in the Marcellus Shale Basin, a region that diagonally bisects the state from the northeast to the southwest, there have been concerns about what unlocking the new stores of fossil fuel by an unconventional method, called hydraulic fracturing, could mean for the environment. Nearly a decade later, researchers are still working to understand just how the chemicals released and the chemicals used to release them are lingering in the water and air.
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Initial measurements in 2012 showed methane levels at 1960 parts per billion — roughly 50 parts per billion higher than would be expected in a rural area without natural gas development. Three years later that concentration jumped another 100 parts per billion. Atmospheric concentrations without natural gas development rose at 6 parts per billion, so this increase is quite substantial compared to the global increase, according to DeCarlo.
Overall natural gas production from the Marcellus Shale region has climbed to 16 billion cubic feet per day, which is twice as much as any other unconventional natural gas resource in the country, according to the researchers. Over the last three years alone, production of natural gas from the region more than doubled, despite the fact that there were about half as many new wells drilled in 2015 as there were in 2012, according to Pennsylvania Department of Environmental Protection figures cited in the paper.
“Though the rate at which new wells are being drilled and completed has slowed down, the overall infrastructure, and production has increased,” DeCarlo said. “That means that the volume of gas moving through pipelines, compressor stations and processing plants is increasing. If the leakage rate of methane is constant per cubic foot of gas, it would not be surprising that the background methane has increased as much as it has while other pollutants like carbon monoxide, which is more associated with drilling and trucking, are showing a decline.”
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Physics
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How To Keep Cool Without Costing The Earth
ABOUT 6% of the electricity generated in America is used to power air-conditioning systems that cool homes and offices. As countries such as Brazil, China and India grow richer, they will surely do likewise. Not only is that expensive for customers, it also raises emissions of greenhouse gases in the form both of carbon dioxide from burning power-station fuel and of the hydrofluorocarbons air conditioners use as refrigerants.
As they describe in a paper in this week’s Science, Ronggui Yang and Xiaobo Yin of the University of Colorado, in Boulder, have a possible alternative to all this. They have invented a film that can cool buildings without the use of refrigerants and, remarkably, without drawing any power to do so. Better yet, this film can be made using standard roll-to-roll manufacturing methods at a cost of around 50 cents a square metre.
The new film works by a process called radiative cooling. This takes advantage of that fact that Earth’s atmosphere allows certain wavelengths of heat-carrying infrared radiation to escape into space unimpeded. Convert unwanted heat into infrared of the correct wavelength, then, and you can dump it into the cosmos with no come back.
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Dr Yang’s and Dr Yin’s film, by contrast, was made of polymethylpentene, a commercially available, transparent plastic sold under the brand name TPX. Into this they mixed tiny glass beads. They then drew the result out into sheets about 50 millionths of a metre (microns) thick, and silvered those sheets on one side. When laid out on a roof, the silver side is underneath. Incident sunlight is thus reflected back through the plastic, which stops it heating the building below.
Preventing something warming up is not, though, the same as cooling it. The key to doing this is the glass beads. Temperature maintenance is not a static process. All objects both absorb and emit heat all the time, and the emissions are generally in the form of infrared radiation. In the case of the beads, the wavelength of this radiation is determined by their diameter. Handily, those with a diameter of about eight microns emit predominantly at wavelengths which pass straight through the infrared “window” in the atmosphere. Since the source of the heat that turns into this infrared is, in part, the building below, the effect is to cool the building.
