Heat-related deaths likely to increase significantly as global temperatures rise, warn researchers

Thermometer in a heat wave

The world needs to keep global temperatures in check by meeting the goals set out in the Paris Agreement, or more people could die because of extreme temperatures, say authors of a new study in the letters section of Springer's journal Climatic Change.

The Paris Agreement, adopted in 2015 under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), binds nations to hold warming well below 2 degrees Celsius (°C) in global mean temperature, relative to pre-industrial levels. It also urges countries to make additional efforts to limit warming to 1.5°C.

Led by researchers at the London School of Hygiene & Tropical Medicine (LSHTM), this is the first study that evaluates global temperature-related health impacts under scenarios consistent with the Agreement. The researchers assessed the mortality impacts projected for a range of temperature increases, either compatible with the thresholds set in Paris (1.5°C and 2°C) or higher (3°C and 4°C). These projections took into account how an increase in heat-related deaths might be offset against a decrease in deaths due to cold, as global temperatures rise.

The scope of the study allowed global comparisons across various areas of the world. The team at LSHTM first analyzed historical data on temperature-related deaths from 451 locations in 23 countries with different socio-economic and climatic conditions. They then projected changes in mortality under climate scenarios consistent with the various increases in global temperature, while keeping demographic distributions and temperature-health risks constant.

The results indicated dramatic increases of heat-related deaths under extreme warming (3°C and 4°C) compared to the mildest threshold (1.5°C), with additional excess mortality ranging from +0.73 per cent to +8.86 per cent across all regions. The net difference remained positive and high in most of the areas, even when potential decreases in cold-related deaths were considered.

The picture was more complex when comparing 2°C versus 1.5°C warming. A net increase in deaths was still projected for warmer regions such as South America, South Europe, and South-East Asia (with changes ranging from +0.19 per cent to +0.72 per cent), while in cooler regions the excess mortality was predicted to stay stable or drop slightly.

The results support the assessment of an upcoming Special Report of the Intergovernmental Panel on Climate Change, scheduled for approval in October, that evaluates the health risks associated with 1.5°C and 2°C of warming.

"Our projections suggest that large increases in temperature-related deaths could be limited in most regions if warming was kept below 2°C," explains Ana Maria Vicedo-Cabrera, the first author of the study. "Under extreme changes in climate, large parts of the world could experience a dramatic increase in excess mortality due to heat. This would not be balanced by decreases in cold-related deaths. Efforts to limit the increase in global temperature to below 1.5°C could provide additional benefits in tropical or arid regions, including the most populous and often poorest countries."

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New means to fight 'un-killable' bacteria in healthcare settings

Dr. Dao Nguyen looking at Pseudomonas aeruginosa that has been listed among the "nightmare bacteria" by the Centers for Disease Control and Prevention (CDC) in the United States, with an estimated 51,000 healthcare-associated infections each year resulting in around 400 deaths. P. aeruginosa is a common cause of healthcare-associated infections such as pneumonia, bloodstream or urinary tract infections, and surgical site infections.

Scientists at the Research Institute of the McGill University Health Centre (RI-MUHC) have identified new means of fighting drug-tolerant bacteria, a growing global threat as menacing as drug-resistant microbes. Little is known about the mechanisms leading to tolerance, a strategy that makes bacteria "indifferent" to antibiotics and almost "un-killable," which results in chronic infections extremely difficult to treat and cure.

The RI-MUHC's research team discovered a new cellular target that can weaken the bacterium Pseudomonas aeruginosa, a daunting microbe which can become highly tolerant to many antibiotics, and thus refractory to antibiotic therapy. The team's findings are published this week in the Proceedings of the National Academy of Sciences (PNAS).

"We identified a new function important to antibiotic tolerance, which could be targeted to enhance the activity of our current antibiotics," says lead study author Dr. Dao Nguyen, a scientist from the Translational Research in Respiratory Diseases Program at the RI-MUHC and an associate professor of Medicine at McGill University. "This is critical if we want to improve the efficacy of our antibiotics and prevent such treatments from failing."

P. aeruginosa lung infection ,is the leading cause of death for thousands of people living with cystic fibrosis. This bacterium also causes many other serious infections in which in people with weakened defenses and immune system.

"P. aeruginosa causes lifelong lung infections in individuals with cystic fibrosis, and these infections cannot be cleared, even by cocktails of the most potent antibiotics available," says Dr. Nguyen, who is also a respirologist at the McGill University Health Centre.

A "Nightmare bacteria" that grows slowly

P. aeruginosa has been listed among the "nightmare bacteria" by the Centers for Disease Control and Prevention (CDC) in the United States, with an estimated 51,000 healthcare-associated infections each year resulting in around 400 deaths. It is a common cause of healthcare-associated infections such as pneumonia, bloodstream or urinary tract infections, and surgical site infections

"Many bacteria, such as P. aeruginosa, when they grow slowly or do not grow at all, become tolerant to antibiotics," explains Dr. Nguyen. "This is a crucial problem because many chronic infections are caused by bacteria that are slow growing or enter a dormant state when they reside in a living host, and this causes treatments to fail or infections to relapse in patients."

A new enzyme target for antibiotics

In this newest research, Dr. Nguyen and her team have discovered that when P. aeruginosa is under stress or lacking nutrients, it uses a stress signaling system and defense enzyme (superoxide dismutase) to modify its cell membrane, making it less permeable to molecules and preventing antibiotics from penetrating the cell.

Researchers found that inhibition of the enzyme activity or the stress signaling system could render the pathogen more susceptible to antibiotics.

"Up until now antibiotic tolerance in slow growing bacteria was widely attributed to the fact that targets of antibiotics were not available or inactive in 'dormant' cells. With this research we have shown there is more to it than that" explains Dr. Nguyen. "We identified a new link between the stress defense enzyme, the regulation of membrane permeability and antibiotic tolerance."

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Eyes have a natural version of night vision

The ganglion cell layer of the retina is labelled with red to show the presence of a cell sensitive to motion in the upward direction. In low light, these cells pick up the faintest signals of any kind of motion.

To see under starlight and moonlight, the retina of the eye changes both the software and hardware of its light-sensing cells to create a kind of night vision. Retinal circuits that were thought to be unchanging and programmed for specific tasks are adaptable to different light conditions, say the Duke scientists who identified how the retina reprograms itself for low light.

"To see under starlight, biology has had to reach the limit of seeing an elementary particle from the universe, a single photon," said Greg Field, an assistant professor of neurobiology and biomedical engineering at Duke University. "It's remarkable at night how few photons there are."

The findings, which appear early online in Neuron, show that the reprogramming happens in retinal cells that are sensitive to motion.

Even in the best lighting, identifying the presence and direction of a moving object is key to survival for most animals. But detecting motion with a single point of reference doesn't work very well. So, the retinas of vertebrates have four kinds of motion-sensitive cells, each specifically responsive to a motion that is up, down, right or left.

When an object is moving in precisely one of those directions, that population of neurons will fire strongly, Field said. However, if the motion is halfway between up and left, both populations of cells will fire, but not quite as strongly. The brain interprets that kind of signal as motion going both up and left.

"For complex tasks, the brain uses large populations of neurons, because there's only so much a single neuron can accomplish," Field said.

In humans, these directional neurons account for about 4 percent of the cells that send signals from the retina to the brain. In rodents, it's more like 20 to 30 percent, Field said, because motion detection is vitally important for an animal that other animals really like to eat.

In a study with mouse retinas conducted under a microscope equipped with night vision eye pieces in a very dark room, graduate student Xiaoyang Yao in Field's lab found that the retinal cells sensitive to upward movement change their behavior in low light. The "up" neurons will fire upon detecting any kind of movement, not just upward.

A small sample of mouse retina was placed on an electrode array that can measure the individual firing of hundreds of neurons at once "and then we show it movies," Field said. "Xiaoyang's insight was to go and look at what these cells do in day and night," Field said. "She noticed a difference and wondered why."

When there is much less light available, a weak signal of motion from the 'up' neurons, coupled with a weak signal from any of the other directional cells can help the brain sense movement, similar to the way it interprets two directional signals as being a motion that is something in between.

The loss of motion perception is a common complaint in human patients with severe vision loss. Field said this finding about the adaptability of retinal neurons may help the design of implantable retinal prosthetics in the future.

"A lot of animals choose to forage at night, presumably because it's harder for predators to see," Field said. "But of course, nature is an arms race. Owls and cats have developed highly specialized eyes to see at night. The prey have altered what they have to survive."

For reasons that aren't yet clear, it's only the "up" cells that become motion generalists in low light. Field suspects that up is the most important direction for a prey animal to spot a predator that looms upward as it approaches its prey, but he doesn't have that data yet.

What's important for now is that the eye and brain alter their computation of motion in low-light. "We've learned that large populations of retinal neurons can adapt their function to compensate for different conditions," Field said.

The retina consists of many circuits working in parallel, said Jeffrey Diamond, a senior investigator at the National Institute of Neurological Disorders and Stroke who also studies visual processing in the retina. "We're learning that these circuits are doing different things at different times of day," said Diamond, who was not involved with Field's paper.

Now that Field has found this one adaptation to low light that is driven by changes in both the circuitry and the chemical signals between cells, it begs the question of how many other adaptations are going to be found, Diamond said.

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People show confirmation bias even about which way dots are moving

This visual abstract depicts findings that people show confirmation bias even about which way dots are moving.

People have a tendency to interpret new information in a way that supports their pre-existing beliefs, a phenomenon known as confirmation bias. Once they've made a decision about which house to buy, which school to send their kids to, or which political candidate to vote for, they have a tendency to interpret new evidence such that it reassures them they've made the right call. Now, researchers reporting in Current Biology on September 13 have shown that people will do the same thing even when the decision they've made pertains to a choice that is rather less consequential: which direction a series of dots is moving and whether the average of a series of numbers is greater or less than 50.

"Confirmation biases have previously only been established in the domains of higher cognition or subjective preferences," for example in individuals' preferences for one consumer product or another, says Tobias Donner from University Medical Center Hamburg-Eppendorf (UKE), Germany. "It was rather striking for us to see that people displayed clear signs of confirmation bias when judging on sensory input that we expected to be subjectively neutral to them."

The findings by a team of researchers from UKE and Tel Aviv University, Israel, suggest that confirmation bias is linked to selective attention, a process in which people react to certain bits of information or stimuli and not others when several are presented at the same time. They also set the stage for studies to unravel the underlying brain mechanisms, the researchers say.

Although confirmation bias is well known, it hadn't been clear what drives it. Is it that people, after making a decision, become less sensitive to new information? Or do they actually filter new information so as to reduce conflict with the decision they've already made?

To explore this question, the researchers, including first authors Bharath Talluri and Anne Urai, both from UKE, asked study participants to look at two successive movies featuring a cloud of small white dots on a white computer screen. Their task was to report the direction the coherently moving dots, which was challenging because these dots were embedded in many more dots that moved about randomly. After the first movie, participants were asked to choose between two categorical options: whether the coherent motion pointed clockwise or counterclockwise from a reference line drawn next to the cloud of dots. After the second movie, they were asked to drag the mouse over the screen to indicate their best continuous estimate of the average direction across both movies they had seen.

The experiments showed that participants, after making an initial call based on the first movie, were more likely to use subsequent evidence that was consistent with their initial choice to make a final judgment the second time around. The finding suggests that the initial choice a person made in the simple visual motion task acts as a cue, selectively directing their attention toward incoming information that's in agreement.

In a second series of experiments, the researchers presented a related numerical task. At first, they were asked to judge whether a series of eight two-digit numbers averaged greater or less than 50. In a second, they were asked to provide a continuous estimate of the average between 10 and 90. Again, participants' answers showed a pattern of confirmation bias and selective attention.

The researchers say the findings help to identify the source of confirmation biases, with implications for understanding the bounds of human rationality. For those of us attempting to make informed decisions in the real world, the new study offers a reminder.

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Gut bacteria's shocking secret: They produce electricity

Listeria bacteria transport electrons through their cell wall into the environment as tiny currents, assisted by ubiquitous flavin molecules (yellow dots).

While bacteria that produce electricity have been found in exotic environments like mines and the bottoms of lakes, scientists have missed a source closer to home: the human gut.

University of California, Berkeley, scientists discovered that a common diarrhea-causing bacterium, Listeria monocytogenes, produces electricity using an entirely different technique from known electrogenic bacteria, and that hundreds of other bacterial species use this same process.

Many of these sparking bacteria are part of the human gut microbiome, and many, like the bug that causes the food-borne illness listeriosis, which can also cause miscarriages, are pathogenic. The bacteria that cause gangrene (Clostridium perfringens) and hospital-acquired infections (Enterococcus faecalis) and some disease-causing streptococcus bacteria also produce electricity. Other electrogenic bacteria, like Lactobacilli, are important in fermenting yogurt, and many are probiotics.

"The fact that so many bugs that interact with humans, either as pathogens or in probiotics or in our microbiota or involved in fermentation of human products, are electrogenic -- that had been missed before," said Dan Portnoy, a UC Berkeley professor of molecular and cell biology and of plant and microbial biology. "It could tell us a lot about how these bacteria infect us or help us have a healthy gut."

The discovery will be good news for those currently trying to create living batteries from microbes. Such "green" bioenergetic technologies could, for example, generate electricity from bacteria in waste treatment plants.

The research will be posted online Sept. 12 in advance of Oct. 4 print publication in the journal Nature.

Breathing metal

Bacteria generate electricity for the same reason we breathe oxygen: to remove electrons produced during metabolism and support energy production. Whereas animals and plants transfer their electrons to oxygen inside the mitochondria of every cell, bacteria in environments with no oxygen -- including our gut, but also alcohol and cheese fermentation vats and acidic mines -- have to find another electron acceptor. In geologic environments, that has often been a mineral -- iron or manganese, for example -- outside the cell. In some sense, these bacteria "breathe" iron or manganese.

Transferring electrons out of the cell to a mineral requires a cascade of special chemical reactions, the so-called extracellular electron transfer chain, which carries the electrons as a tiny electrical current. Some scientists have tapped that chain to make a battery: stick an electrode in a flask of these bacteria and you can generate electricity.

The newly discovered extracellular electron transfer system is actually simpler than the already known transfer chain, and seems to be used by bacteria only when necessary, perhaps when oxygen levels are low. So far, this simpler electron transfer chain has been found in bacteria with a single cell wall -- microbes classified as gram-positive bacteria -- that live in an environment with lots of flavin, which are derivatives of vitamin B2.

"It seems that the cell structure of these bacteria and the vitamin-rich ecological niche that they occupy makes it significantly easier and more cost effective to transfer electrons out of the cell," said first author Sam Light, a postdoctoral fellow. "Thus, we think that the conventionally studied mineral-respiring bacteria are using extracellular electron transfer because it is crucial for survival, whereas these newly identified bacteria are using it because it is 'easy.'"

To see how robust this system is, Light teamed up with Caroline Ajo-Franklin from Lawrence Berkeley National Laboratory, who explores the interactions between living microbes and inorganic materials for possible applications in carbon capture and sequestration and bio-solar energy generation.

She used an electrode to measure the electric current that streams from the bacteria -- up to 500 microamps -- confirming that it is indeed electrogenic. In fact, they make about as much electricity -- some 100,000 electrons per second per cell -- as known electrogenic bacteria.

Light is particularly intrigued by the presence of this system in Lactobacillus, bacteria crucial to the production of cheese, yogurt and sauerkraut. Perhaps, he suggests, electron transport plays a role in the taste of cheese and sauerkraut.

"This is a whole big part of the physiology of bacteria that people didn't realize existed, and that could be potentially manipulated," he said.

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Astronomers witness birth of new star from stellar explosion

Unlike most stellar explosions that fade away, supernova SN 2012au continues to shine today thanks to a powerful new pulsar.

The explosions of stars, known as supernovae, can be so bright they outshine their host galaxies. They take months or years to fade away, and sometimes, the gaseous remains of the explosion slam into hydrogen-rich gas and temporarily get bright again -- but could they remain luminous without any outside interference?

That's what Dan Milisavljevic, an assistant professor of physics and astronomy at Purdue University, believes he saw six years after "SN 2012au" exploded.

"We haven't seen an explosion of this type, at such a late timescale, remain visible unless it had some kind of interaction with hydrogen gas left behind by the star prior to explosion," he said. "But there's no spectral spike of hydrogen in the data -- something else was energizing this thing."

As large stars explode, their interiors collapse down to a point at which all their particles become neutrons. If the resulting neutron star has a magnetic field and rotates fast enough, it may develop into a pulsar wind nebula.

This is most likely what happened to SN 2012au, according to findings published in the Astrophysical Journal Letters.

"We know that supernova explosions produce these types of rapidly rotating neutron stars, but we never saw direct evidence of it at this unique time frame," Milisavljevic said. "This a key moment when the pulsar wind nebula is bright enough to act like a lightbulb illuminating the explosion's outer ejecta."

SN 2012au was already known to be extraordinary -- and weird -- in many ways. Although the explosion wasn't bright enough to be termed a "superluminous" supernova, it was extremely energetic and long-lasting, and dimmed in a similarly slow light curve.

Milisavljevic predicts that if researchers continue to monitor the sites of extremely bright supernovae, they might see similar transformations.

"If there truly is a pulsar or magnetar wind nebula at the center of the exploded star, it could push from the inside out and even accelerate the gas," he said. "If we return to some of these events a few years later and take careful measurements, we might observe the oxygen-rich gas racing away from the explosion even faster."

Superluminous supernovae are a hot topic in transient astronomy. They're potential sources of gravitational waves and black holes, and astronomers think they might be related to other kinds of explosions, like gamma ray bursts and fast radio bursts. Researchers want to understand the fundamental physics behind them, but they're difficult to observe because they're relatively rare and happen so far from Earth.

Only the next generation of telescopes, which astronomers have dubbed "Extremely Large Telescopes," will have the ability to observe these events in such detail.

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A prehistoric thirst for craft beer

This is the site location and artifacts analyzed. (A) The location of Raqefet Cave and three additional Natufian sites in Mt. Carmel; (B) field photos of the studied boulder mortars (BM1,2) and the location of BM3 on the cave floor (scale bar and arrow: 20 cm); (C) a functional reconstruction of the mortars: a boulder mortar used to store plants in a basket with a stone slab on top, and a bedrock mortar used for pounding and cooking plants and brewing beer.

A new study published in the Journal of Archaeological Science: Reports suggests beer brewing practices existed in the Eastern Mediterranean over five millennia before the earliest known evidence, discovered in northern China. In an archaeological collaboration project between Stanford University in the United States, and University of Haifa, Israel, archeologists analyzed three stone mortars from a 13,000-year old Natufian burial cave site in Israel. Their analysis confirmed that these mortars were used for brewing of wheat/barley, as well as for food storage.

"Alcohol making and food storage were among the major technological innovations that eventually led to the development of civilizations in the world, and archaeological science is a powerful means to help reveal their origins and decode their contents," said Li Liu, PhD, Department of East Asian Languages and Cultures, Stanford University, USA. "We are excited to have the opportunity to present our findings, which shed new light on a deeper history of human society."

The earliest archaeological evidence for cereal-based beer brewing even before the advent of agriculture comes from the Natufians, semi-sedentary, foraging people, living in the Eastern Mediterranean between the Paleolithic and the Neolithic periods, following the last Ice Age. The Natufians at Raqefet Cave collected locally available plants, stored malted seeds, and made beer as a part of their rituals.

"The Natufian remains in Raqefet Cave never stop surprising us," said Prof. Dani Nadel, Zinman Institute of Archaeology, University of Haifa, Israel, who was also an excavator of the site. "We exposed a Natufian burial area with about 30 individuals; a wealth of small finds such as flint tools, animal bones and ground stone implements, and about 100 stone mortars and cupmarks. Some of the skeletons are well-preserved and provided direct dates and even human DNA, and we have evidence for flower burials and wakes by the graves.

"And now, with the production of beer, the Raqefet Cave remains provide a very vivid and colorful picture of Natufian lifeways, their technological capabilities and inventions."

After five seasons of excavations and a wide range of studies, the current study employed experimental archaeology, contextual examination, use-wear and residue analyses. The results indicate that the Natufians exploited at least seven plant types associated with the mortars, including wheat or barley, oat, legumes and bast fibers (including flax). They packed plant-foods in fiber-made containers and stored them in boulder mortars. They used bedrock mortars for pounding and cooking plant-foods, and for brewing wheat/barley-based beer, likely served in ritual feasts 13,000 years ago.

The use-wear patterns and microbotanical assemblage suggest that two of the three examined boulder mortars were used as storage containers for plant foods -- including wheat/barley malts. Likely, they were covered with lids, probably made of stone slabs and other materials. The foods are likely to have been placed in baskets made of bast fibers for easy handing. The deep narrow shafts may have provided cool conditions suitable for storing food, especially for keeping cereal malts.

Combining use-wear and residue data, the third mortar studied was interpreted as a multi-functional vessel for food preparation, which included pounding plant foods and brewing wheat/barley-based beer, probably with legumes and other plants as additive ingredients.

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Famous theory of the living Earth upgraded to 'Gaia 2.0'

Earth

A time-honoured theory into why conditions on Earth have remained stable enough for life to evolve over billions of years has been given a new, innovative twist.

For around half a century, the 'Gaia' hypothesis has provided a unique way of understanding how life has persisted on Earth.

It champions the idea that living organisms and their inorganic surroundings evolved together as a single, self-regulating system that has kept the planet habitable for life -- despite threats such as a brightening Sun, volcanoes and meteorite strikes.

However, Professor Tim Lenton from the University of Exeter and famed French sociologist of science Professor Bruno Latour are now arguing that humans have the potential to 'upgrade' this planetary operating system to create "Gaia 2.0."

They believe that the evolution of both humans and their technology could add a new level of "self-awareness" to Earth's self-regulation, which is at the heart of the original Gaia theory.

As humans become more aware of the global consequences of their actions, including climate change, a new kind of deliberate self-regulation becomes possible where we limit our impacts on the planet.

Professors Lenton and Latour suggest that this "conscience choice" to self-regulate introduces a "fundamental new state of Gaia" -- which could help us achieve greater global sustainability in the future.

However, such self-aware self-regulation relies on our ability to continually monitor and model the state of the planet and our effects upon it.

Professor Lenton, Director of Exeter's new Global Systems Institute, said: "If we are to create a better world for the growing human population this century then we need to regulate our impacts on our life support-system, and deliberately create a more circular economy that relies -- like the biosphere -- on the recycling of materials powered by sustainable energy."

The original Gaia Theory was developed in the late 1960's by James Lovelock, a British scientist and inventor. It suggested that both the organic and inorganic components of Earth evolved together as one single, self-regulating system which can control global temperature and atmospheric composition to maintain its own habitability.

The new perspective article is published in leading journal Science on September 14, 2018.

It follows recent research, led by Professor Lenton, which offered a fresh solution to how the Gaia hypothesis works in real terms: Stability comes from "sequential selection" in which situations where life destabilises the environment tend to be short-lived and result in further change until a stable situation emerges, which then tends to persist.

Once this happens, the system has more time to acquire further properties that help to stabilise and maintain it -- a process known as "selection by survival alone."

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Stunning details of spiral galaxy NGC 3981

FORS2, an instrument mounted on ESO's Very Large Telescope captured the spiral galaxy NGC 3981 in all its glory. The image, captured during the ESO Cosmic Gems Programme, showcases the beauty of the southern skies when conditions don't allow scientific observations to be made.

This wonderful image shows the resplendent spiral galaxy NGC 3981 suspended in the inky blackness of space. This galaxy, which lies in the constellation of Crater (the Cup), was imaged in May 2018 using the FOcal Reducer and low dispersion Spectrograph 2 -- FORS2) instrument on ESO's Very Large Telescope -- VLT).

FORS2 is mounted on Unit Telescope 1 (Antu) of the VLT at ESO's Paranal Observatory in Chile. Amongst the host of cutting-edge instruments mounted on the four Unit Telescopes of the VLT, FORS2 stands apart due to its extreme versatility. This "Swiss Army knife" of an instrument is able to study a variety of astronomical objects in many different ways -- as well as being capable of producing beautiful images like this one.

The sensitive gaze of FORS2 revealed NGC 3981's spiral arms, strewn with vast streams of dust and star-forming regions, and a prominent disc of hot young stars. The galaxy is inclined towards Earth, allowing astronomers to peer right into the heart of this galaxy and observe its bright centre, a highly energetic region containing a supermassive black hole. Also shown is NGC 3981's outlying spiral structure, some of which appears to have been stretched outwards from the galaxy, presumably due to the gravitational influence of a past galactic encounter.

NGC 3981 certainly has many galactic neighbours. Lying approximately 65 million light years from Earth, the galaxy is part of the NGC 4038 group, which also contains the well-known interacting Antennae Galaxies. This group is part of the larger Crater Cloud, which is itself a smaller component of the Virgo Supercluster, the titanic collection of galaxies that hosts our own Milky Way galaxy.

NGC 3981 is not the only interesting feature captured in this image. As well as several foreground stars from our own galaxy, the Milky Way, FORS2 also captured a rogue asteroid streaking across the sky, visible as the faint line towards the top of the image. This particular asteroid has unwittingly illustrated the process used to create astronomical images, with the three different exposures making up this image displayed in the blue, green and red sections of the asteroid's path.

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Turtle species in serious decline: Broad ecological impacts

Agassiz's desert tortoise.

Approximately 61 percent of the world's 356 turtle species are threatened or already extinct, and the decline could have ecological consequences.

These findings are according to a paper in the journal BioScience synthesizing the global status of turtles and their ecological roles by scientists from the U.S. Geological Survey, Tennessee Aquarium Conservation Institute, University of California, Davis, and the University of Georgia.

Turtles are now among the most threatened groups of vertebrate animals on earth, more so than birds, mammals, fish or amphibians. These animals outlived the dinosaurs and have roamed the earth for more than 200 million years. Reasons for the decline of turtles worldwide include habitat destruction, over-exploitation for pets and food, disease and climate change.

"Our goal is to provide resource managers with a full picture of the state of these iconic animals worldwide, and what long-term impacts our environment might experience if populations continue to decrease and species loss continues," said USGS scientist and lead author of the study Jeffrey Lovich. "Turtles contribute to the health of many environments, including desert, wetland, freshwater and marine ecosystems, and their decline may lead to negative effects on other species, including humans, that may not be immediately apparent."

Scientists synthesized existing published studies to bring attention to the status of turtles and identify what may be lost from an ecological perspective if current trends hold and they continue to decline and disappear.

This paper provides the first major review of the various functional roles that large populations and diverse communities of turtles provide from an ecological perspective. This includes maintaining healthy food webs, dispersing seeds and creating habitats necessary for other species.

"Our purpose is to inform the public of the many critical ecological roles turtles perform on a global scale and bring awareness to the plight of these emblematic animals whose ancestors walked with the dinosaurs," said professor emeritus and senior ecologist Whit Gibbons, at the University of Georgia's Savannah River Ecology Laboratory and Odum School of Ecology. "These modern descendants of an ancient lineage are touchstones for how human influences are causing the decline of so much of the world's wildlife. Our hope is that everyone will be encouraged to engage in concerted efforts to conserve their well-earned legacy as part of our natural habitats."

Turtles can be major players in ecosystem food webs because they can be herbivores, omnivores or carnivores. They range from specialists that feed on one to a few food sources, to generalists, feeding on a wide range of items. Their diverse feeding habits allow them to influence the structure of other communities in their habitat. Some turtle species occur in dense numbers that can yield hundreds of pounds of turtles per acre, making them ecologically important by virtue of their mass alone. Such large masses of turtles equate to large amounts of potential food for organisms that feed on turtles or their eggs.

Turtles can be important for dispersing the seeds of dozens of plant species. Some turtle species may even be the primary seed dispersal agents for specific plants. Not all seeds are destroyed by the digestive tract. In fact, there are specific seeds that exhibit higher rates of germination after being eaten and passed by turtles.

Some turtles, like Agassiz's desert tortoise in the American Southwest and the gopher tortoise in the American Southeast, dig deep burrows creating habitat for other species. For example, the gopher tortoise can dig burrows over 30 feet long. The mounds of soil near the entrance of the burrows can create new habitat for some plant species, increasing overall plant diversity near burrow entrances. The burrows are used by hundreds of other species including spiders, insects, snakes, amphibians, other reptiles, rabbits, foxes and even bobcats.

"The ecological importance of turtles, especially freshwater turtles, is underappreciated, and they are generally understudied by ecologists," says Josh Ennen, research scientist at the Tennessee Aquarium Conservation Institute. "The alarming rate of turtle disappearance could profoundly affect how ecosystems function as well as the structure of biological communities around the globe."

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Wild animals were routinely captured and traded in ancient Mesoamerica

Puma skull from the Motmot burial.

New evidence from the Maya city of Copan, in Honduras, reveals that ancient Mesoamericans routinely captured and traded wild animals for symbolic and ritual purposes, according to a study published September 12, 2018 in the open-access journal PLOS ONE by Nawa Sugiyama from George Mason University, Virginia, USA, and colleagues.

Ancient Mesoamerican cultures used wild animals such as puma and jaguar for many purposes, including in symbolic displays of status and power, as subjects of ritual sacrifice, and as resources for processing into venison or craft products. Evidence of wild animal use in ancient Mesoamerica dates back to the Teotihuacan culture in what is now central Mexico (A.D. 1-550). Archaeological findings of indigenous Mesoamerican animal management strategies have traditionally been underemphasized, due to the paucity of large domesticated game in the New World in comparison to the devastating impact of European livestock introduced in the 1500s. In this study, the research team analyzed archaeological samples of wild animals excavated from five ritual sites in the Maya city of Copan (A.D. 426-822), in Honduras.

The team performed stable isotope analyses on bone and teeth from puma, jaguar and other unidentified felids along with deer, owl, spoonbill, and crocodile, to determine the diet and geographical origin of the animals. Some of the felid specimens tested, including puma and jaguar, had high levels of C4 intake indicative of an anthropogenic diet despite the absence of indicators of captive breeding. Oxygen isotope levels in deer and felid specimens suggest that some animals and derived craft products (e.g. pelts) used in ritual practices originated in distant regions of the Copan Valley.

These findings confirm previous research showing that Mesoamerican cultures kept wild animals in captivity for ritual purposes and reveal that animal trade networks across ancient Mesoamerica were more extensive than previously thought.

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Ancient bird bones redate human activity in Madagascar by 6,000 years

Disarticulation marks on the base of the tarsometatarsus. These cut marks were made when removing the toes from the foot.

Analysis of bones, from what was once the world's largest bird, has revealed that humans arrived on the tropical island of Madagascar more than 6,000 years earlier than previously thought -- according to a study published today, 12 September 2018, in the journal Science Advances.

A team of scientists led by international conservation charity ZSL (Zoological Society of London) discovered that ancient bones from the extinct Madagascan elephant birds (Aepyornis and Mullerornis) show cut marks and depression fractures consistent with hunting and butchery by prehistoric humans. Using radiocarbon dating techniques, the team were then able to determine when these giant birds had been killed, reassessing when humans first reached Madagascar.

Previous research on lemur bones and archaeological artefacts suggested that humans first arrived in Madagascar 2,400-4,000 years ago. However, the new study provides evidence of human presence on Madagascar as far back as 10,500 years ago -- making these modified elephant bird bones the earliest known evidence of humans on the island.

Lead author Dr James Hansford from ZSL's Institute of Zoology said: "We already know that Madagascar's megafauna -- elephant birds, hippos, giant tortoises and giant lemurs -- became extinct less than 1,000 years ago. There are a number of theories about why this occurred, but the extent of human involvement hasn't been clear.

"Our research provides evidence of human activity in Madagascar more than 6,000 years earlier than previously suspected -- which demonstrates that a radically different extinction theory is required to understand the huge biodiversity loss that has occurred on the island. Humans seem to have coexisted with elephant birds and other now-extinct species for over 9,000 years, apparently with limited negative impact on biodiversity for most of this period, which offers new insights for conservation today."

Co-author Professor Patricia Wright from Stony Brook University said: "This new discovery turns our idea of the first human arrivals on its head. We know that at the end of the Ice Age, when humans were only using stone tools, there were a group of humans that arrived on Madagascar. We do not know the origin of these people and won't until we find further archaeological evidence, but we know there is no evidence of their genes in modern populations. The question remains -- who these people were? And when and why did they disappear?"

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Discovery of the earliest drawing

This silcrete flake displays a drawing made up of nine lines traced on one of its faces with an ocher implement.

What is a symbol? This is a tough question to answer when tasked with analyzing the earliest graphic productions. What we might today interpret as figurative representations might just be an ancient doodle that had no special purpose. For a long time, archaeologists were convinced the first symbols appeared when Homo sapiens colonized areas of Europe about 40,000 years ago. However, recent archaeological discoveries in Africa, Europe, and Asia suggest the creation and use of symbols emerged much earlier.

For example, the oldest known engraving is a zigzag carved into the shell of a freshwater mussel found in Trinil (Java) within 540,000-year-old archaeological strata. And objects for personal adornment have been unearthed at several archaeological sites in Africa dating back to 70,000 to 120,000 years before the present.

In the new article, the international team that includes scientists from the PACEA (CNRS / University of Bordeaux / French Ministry of Culture) and TRACES (CNRS / University of Toulouse-Jean Jaurès / French Ministry of Culture) research units describe the oldest known abstract drawing made with a piece of ocher used as a pencil. It was identified on the surface of a small piece of siliceous rock (silcrete) while analyzing stone tools collected during an excavation at Blombos Cave in South Africa. The silcrete fragment came from a 73,000-year-old archaeological stratum and bears a crosshatched pattern made up of nine fine lines.

A major methodological challenge was to prove these lines were deliberately drawn by humans. It was primarily tackled by the team's French members, experts in these matters and specialized in the chemical analysis of pigments. First they reproduced the same lines using various techniques: They tried fragments of ocher with a point or an edge and also applied different aqueous dilutions of ocher powder using brushes. Using techniques of microscopic, chemical, and tribological analysis, they then compared their drawings to the ancient original. Their findings confirm the lines were intentionally drawn with a pointed ocher implement on a surface first smoothed by rubbing. The pattern thus constitutes the earliest known drawing, preceding the oldest previously discovered works by at least 30,000 years.

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New color-generation mechanism discovered in 'rainbow' weevil

Left: A photograph of the 'rainbow' weevil, with the rainbow-colored spots on its thorax and elytra (wing casings). Right: A microscope image of the rim of a single rainbow spot, showing the different colors of individual scales.

Researchers from Yale-NUS College and the University of Fribourg in Switzerland have discovered a novel colour-generation mechanism in nature, which if harnessed, has the potential to create cosmetics and paints with purer and more vivid hues, screen displays that project the same true image when viewed from any angle, and even reduce the signal loss in optical fibres. Yale-NUS College Assistant Professor of Science (Life Science) Vinodkumar Saranathan led the study with Dr Bodo D Wilts from the Adolphe Merkle Institute at the University of Fribourg. Dr Saranathan examined the rainbow-coloured patterns in the elytra (wing casings) of a snout weevil from the Philippines, Pachyrrhynchus congestus pavonius, using high-energy X-rays, while Dr Wilts performed detailed scanning electron microscopy and optical modelling. They discovered that to produce the rainbow palette of colours, the weevil utilised a colour-generation mechanism that is so far found only in squid, cuttlefish, and octopuses, which are renowned for their colour-shifting camouflage. The study was published in the peer-reviewed journal Small.

P. c. pavonius, or the "Rainbow" Weevil, is distinctive for its rainbow-coloured spots on its thorax and elytra. These spots are made up of nearly-circular scales arranged in concentric rings of different hues, ranging from blue in the centre to red at the outside, just like a rainbow. While many insects have the ability to produce one or two colours, it is rare that a single insect can produce such a vast spectrum of colours. Researchers are interested to figure out the mechanism behind the natural formation of these colour-generating structures, as current technology is unable to synthesise structures of this size.

"The ultimate aim of research in this field is to figure out how the weevil self-assembles these structures, because with our current technology we are unable to do so," Dr Saranathan said. "The ability to produce these structures, which are able to provide a high colour fidelity regardless of the angle you view it from, will have applications in any industry which deals with colour production. We can use these structures in cosmetics and other pigmentations to ensure high-fidelity hues, or in digital displays in your phone or tablet which will allow you to view it from any angle and see the same true image without any colour distortion. We can even use them to make reflective cladding for optical fibres to minimise signal loss during transmission."

Read more at Science Daily

September 11 2018 Memorial streams

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Legacy of NASA's Dawn, near the end of its mission

Artist's concept of NASA's Dawn spacecraft orbiting dwarf planet Ceres.

NASA's Dawn mission is drawing to a close after 11 years of breaking new ground in planetary science, gathering breathtaking imagery, and performing unprecedented feats of spacecraft engineering.

Dawn's mission was extended several times, outperforming scientists' expectations in its exploration of two planet-like bodies, Ceres and Vesta, that make up 45 percent of the mass of the main asteroid belt. Now the spacecraft is about to run out of a key fuel, hydrazine. When that happens, most likely between mid-September and mid-October, Dawn will lose its ability to communicate with Earth. It will remain in a silent orbit around Ceres for decades.

"Although it will be sad to see Dawn's departure from our mission family, we are intensely proud of its many accomplishments," said Lori Glaze, acting director of the Planetary Science Division at NASA Headquarters in Washington. "Not only did this spacecraft unlock scientific secrets at these two small but significant worlds, it was also the first spacecraft to visit and orbit bodies at two extraterrestrial destinations during its mission. Dawn's science and engineering achievements will echo throughout history."

When Dawn launched from Cape Canaveral Air Force Station in Florida in September 2007, strapped on a Delta II-Heavy rocket, scientists and engineers had an idea of what Ceres and Vesta looked like. Thanks to ground- and space-based telescopes, including NASA's Hubble Space Telescope, the bodies in the asteroid belt between Mars and Jupiter were visible -- but even the best pictures were fuzzy.

From 2011 to 2012, Dawn swept over Vesta, capturing images that exceeded everyone's imaginings -- craters, canyons and even mountains. Then on Ceres in 2015, Dawn showed us a cryovolcano and mysterious bright spots, which scientists later found might be salt deposits produced by the exposure of briny liquid from Ceres' interior. Through Dawn's eyes, these bright spots were especially stunning, glowing like diamonds scattered across the dwarf planet's surface.

"Dawn's legacy is that it explored two of the last uncharted worlds in the inner Solar System," said Marc Rayman of NASA's Jet Propulsion Laboratory in Pasadena California, who serves as Dawn's mission director and chief engineer. "Dawn has shown us alien worlds that for two centuries were just pinpoints of light amidst the stars. And it has produced these richly detailed, intimate portraits and revealed exotic, mysterious landscapes unlike anything we've ever seen."

Engineering Feats

Dawn is the only spacecraft to orbit a body in the asteroid belt. And it is the only spacecraft to orbit two extraterrestrial destinations. These feats were possible thanks to ion propulsion, a tremendously efficient propulsion system familiar to science-fiction fans and space enthusiasts. Dawn pushed the limits of the system's capabilities and stamina, showing how useful it is for other missions that aim to visit multiple destinations.

Pushed by ion propulsion, Dawn reached Vesta in 2011 and investigated it from surface to core during 14 months in orbit. In 2012, engineers maneuvered Dawn out of orbit and steered it though the asteroid belt for more than two years before inserting it into orbit around the dwarf planet Ceres, where it has been collecting data since 2015.

Window into the Past

All the while, scientists gained new insight into the early stages of our Solar System, fulfilling Dawn's objective. The mission was named for its purpose: to learn more about the dawn of the Solar System. It targeted Ceres and Vesta because they function as time capsules, intact survivors of the earliest part of our history. And the duo delivered, giving scientists insight into the original building blocks of the Solar System.

"Vesta and Ceres have each told their story of how and where they formed, and how they evolved -- a fiery magmatic history that led to rocky Vesta and a cooler, water-rich history that resulted in the ancient ocean world Ceres," said Carol Raymond of JPL, principal investigator of the Dawn mission. "These treasure troves of information will continue to help us understand other bodies in the Solar System far into the future."

Spectacular Ceres

There was so much that scientists didn't know about Ceres before Dawn arrived. Raymond wondered whether they might find Ceres covered with a smooth, young surface -- an enormous cue ball with a frozen crust. Instead, they found the dwarf planet wearing the chemistry of its old ocean. "What we found was completely mind-blowing. Ceres' history is just splayed all over its surface," she said.

Some of the dazzling bright spots turned out to be brilliant salty deposits, composed mainly of sodium carbonate that made its way to the surface in a slushy brine from within or below the crust.

The findings reinforce the idea that dwarf planets, not just icy moons like Enceladus and Europa, could have hosted oceans during their history -- and potentially still do. Analyses from Dawn data suggest there may still be liquid under Ceres' surface and that some regions were geologically active relatively recently, feeding from a deep reservoir.

One of Dawn's biggest reveals on Ceres lay in the region of Ernutet Crater. Organic molecules were found in abundance. Organics are among the building blocks of life, though Dawn's data can't determine if Ceres' organics were formed by biological processes.

"There is growing evidence that the organics in Ernutet came from Ceres' interior, in which case they could have existed for some time in the early interior ocean," said Julie Castillo-Rogez, Dawn's project scientist and deputy principal investigator at JPL.

Vibrant Vesta

At Vesta, Dawn's investigation into the early Solar System found a 4.5-billion-year-old witness it could interrogate. Dawn mapped the craters of the planet-like world and revealed that its northern hemisphere had experienced more large impacts than expected, suggesting there were more large objects in the asteroid belt early on than scientists thought.

Vesta held other surprises as well. While it's technically classified as an asteroid, that label belies the rich and varied terrain Dawn revealed, and the planet-like processes that Vesta experienced. Hubble had relayed images of a mountain at the center of an enormous basin now called Rheasilvia. Dawn's mapping showed it to be twice the height of Mt. Everest, and it revealed canyons that rival the Grand Canyon in size. Dawn also confirmed Vesta as the source of a very common family of meteorites.

Now, near the end of Dawn's second extended mission at Ceres, the spacecraft has continued to gather high-resolution images, gamma ray and neutron spectra, infrared spectra, and gravity data. Almost once a day, it will swoop over Ceres about 22 miles (35 kilometers) from its surface -- only about three times the altitude of a passenger jet -- gathering valuable data until it expends the last of the hydrazine that feeds thrusters controlling its orientation. Dawn's reaction wheels failed earlier in the mission, leaving it heavily dependent on this key fuel. When Dawn runs out in the next month or two, the spacecraft will lose its ability to communicate with Earth, but it must not crash into Ceres.

Because Ceres has conditions of interest to scientists who study chemistry that leads to the development of life, NASA follows strict planetary protection protocols for the disposal of the Dawn spacecraft. Unlike Cassini, which deliberately plunged into Saturn's atmosphere to protect the system from contamination -- Dawn will remain in orbit around Ceres, which has no atmosphere.

Read more at Science Daily

Global warming pushing alpine species higher and higher

Populations of northern pocket gopher in Nevada have lost 70 per cent of their range, according to University of British Columbia research.

For every one-degree-Celsius increase in temperature, mountaintop species shift upslope 100 metres, shrinking their inhabited area and resulting in dramatic population declines, new research by University of British Columbia zoologists has found.

The study -- the first broad review of its kind -- analyzed shifts in elevation range in 975 populations of plants, insects and animals.

"Most mountaintop species we looked at are responding to warming temperatures by shifting upslope to live in cooler environments. As they move towards the mountaintop, the area they live within gets smaller and smaller. This supports predictions that global warming could eventually drive extinctions among species at the top," says Benjamin Freeman, lead author of the study and a postdoctoral researcher at the UBC Biodiversity Research Centre.

The study found that most mountaintop species have moved upward, including:

• The northern pocket gopher in Nevada's Ruby Mountains lost more than 70 per cent of its inhabited area over the past 80 years as a 1.1-degree temperature increase drove populations upslope.
• The mountain burnet butterfly in the French Pyrenees adjusted to a one-degree temperature increase by shifting upslope 430 metres -- losing 79 per cent of its range over the past 50 years.
• An alpine meadow flower in the Himalayas moved upslope more than 600 metres as temperatures rose more than 2.2 degrees in the past 150 years. It lost 29 per cent of its habitat in the region.

The research also found that a few species, such as the white-crowned sparrow in the southern Sierra Nevada mountains in California, moved their entire range down mountains.

"This highlights how complicated responses to climate change are likely to be," says Anna Hargreaves, an assistant professor at McGill University who worked on the study as a postdoctoral researcher at UBC.

"We might be able to predict what happens on average, but predicting how any particular species will respond is a serious challenge. We should be treasuring, archiving and protecting historical data and long-term studies that give us baselines to see how the world is changing."

The research analyzed data from 23 previous surveys and studies, largely conducted over the past 50 years.

"Changes in species' geographical ranges are likely to have important implications for conservation," says Julie Lee-Yaw, study co-author and postdoctoral researcher with the UBC department of botany.

Read more at Science Daily

Three new species of fish discovered in the extreme depths of the Pacific Ocean

Three new species of snailfish were discovered at great depths in the Atacama Trench.

An exploration to one of the deepest places on earth has captured rare footage of what is believed to be three new species of the elusive Snailfish.

Involving a team of 40 scientists from 17 different nations, including Dr Alan Jamieson and Dr Thomas Linley from Newcastle University, UK, the expedition to the Atacama Trench has uncovered a wealth of information about life in one of the deepest places on earth.

Among the new discoveries are what the team believe to be three new species of snailfish.

Temporarily named 'the pink, the blue and the purple Atacama Snailfish', the footage shows the fish feeding and interacting in their secret world 7,500 metres below the surface.

These fish are part of the Liparidae family and do not conform to the preconceived stereotypical image of what a deep-sea fish should look like.

Instead of giant teeth and a menacing frame, the fishes that roam in the deepest parts of the ocean are small, translucent, bereft of scales -- and highly adept at living where few other organisms can. The snailfish will be featured as part of the Challenger Conference 2018 which kicks off at Newcastle University from today and runs until Friday.

Dr Thomas Linley, from Newcastle University, said:

"There is something about the snailfish (fish of the family Liparidae) that allows them to adapt to living very deep. Beyond the reach of other fish they are free of competitors and predators.

"As the footage clearly shows, there are lots of invertebrate prey down there and the snailfish are the top predator, they seem to be quite active and look very well-fed.

"Their gelatinous structure means they are perfectly adapted to living at extreme pressure and in fact the hardest structures in their bodies are the bones in their inner ear which give them balance and their teeth. Without the extreme pressure and cold to support their bodies they are extremely fragile and melt rapidly when brought to the surface."

Amazingly, the team did manage to catch one the new species of snailfish which followed its amphipod prey into one of the traps. The single specimen was in very good condition and, following careful preservation, is currently being described by the Newcastle team with the help of colleagues from the United States and the Natural History Museum, London.

Pioneering technology for exploration of the ultra-deep

The Hadal Trenches are one of the last great frontiers in marine science and the deepest places on Earth.

Mostly located around the Pacific rim in areas where tectonic plate collide and plunge, the seafloor reaches depths close to 11,000 metres (~7 miles) in some areas.

The Atacama Trench, a trench almost 6000 km long and more than 8000 m deep, runs along the west coast of South America.

Newcastle University scientists and engineers have been pioneering technology for the exploration of these ultra-deep environments for the last five years and have to date completed nearly 250 deployments of their novel 'lander' systems.

Using two full-ocean depth (11,000 m) capable landers equipped with HD cameras and traps the Newcastle team assessed the animals found within the trench.

Designed and developed at Newcastle University, the lander is dropped overboard, and free-falls to the ocean floor where it carries out a variety of monitoring and sampling tasks.

It can take four hours for a trap to sink to the bottom and after waiting an additional 12 to 24 hours, the researchers send an acoustic signal to the trap, which releases weights and the lander rises to the surface with the help of floatation.

This allows the team to catch fish specimens and take video footage of life at the bottom of the ocean.

On this latest expedition to the Atacama Trench in the SE Pacific off the coast of Peru and Chile, the team deployed their baited camera system 27 times from 2537 to the deepest point, Richard's Deep, at just over 8000 metres.

More than 100 hours of video and 11,468 photographs were taken at the seabed.

As well as the snailfish, the team also filmed some astonishingly rare footage of long-legged isopods, known as Munnopsids, which are about the size of an adult hand.

These crustaceans have small bodies, extraordinarily long legs and swim backwards and upsides down, propelling themselves with paddles on their ventral side -- their 'tummies' -- before righting themselves on the seafloor and spreading their long walking legs out like a spider.

Read more at Science Daily

Evidence of early planetary shake-up

SwRI scientist studied the binary asteroid Patroclus-Menoetius, shown in this artist’s conception, to determine that a shake-up of the giant planets likely happened early in the solar system’s history, within the first 100 million years.

Scientists at Southwest Research Institute studied an unusual pair of asteroids and discovered that their existence points to an early planetary rearrangement in our solar system.

These bodies, called Patroclus and Menoetius, are targets of NASA's upcoming Lucy mission. They are around 70 miles wide and orbit around each other as they collectively circle the Sun. They are the only large binary known in the population of ancient bodies referred to as the Trojan asteroids. The two swarms of Trojans orbit at roughly the same distance from the Sun as Jupiter, one swarm orbiting ahead of, and the other trailing, the gas giant.

"The Trojans were likely captured during a dramatic period of dynamic instability when a skirmish between the solar system's giant planets -- Jupiter, Saturn, Uranus and Neptune -- occurred," said SwRI Institute Scientist Dr. David Nesvorny. He is the lead author of the paper, "Evidence for Very Early Migration of the Solar System Planets from the Patroclus-Menoetius Binary Jupiter Trojan," published in Nature Astronomy. This shake-up pushed Uranus and Neptune outwards, where they encountered a large primordial population of small bodies thought to be the source of today's Kuiper Belt objects, which orbit at the edge of the solar system. "Many small bodies of this primordial Kuiper Belt were scattered inwards, and a few of those became trapped as Trojan asteroids."

A key issue with this solar system evolution model, however, has been when it took place. In this paper, scientists demonstrate that the very existence of the Patroclus-Menoetius pair indicates that the dynamic instability among the giant planets must have occurred within the first 100 million years of the solar system formation.

Recent models of small body formation suggest that these types of binaries are leftovers of the very earliest times of our solar system, when pairs of small bodies could form directly from a collapsing cloud of "pebbles."

"Observations of today's Kuiper Belt show that binaries like these were quite common in ancient times," said Dr. William Bottke, director of SwRI's Space Studies Department, who coauthored the paper. "Only a few of them now exist within the orbit of Neptune. The question is how to interpret the survivors."

Had the instability been delayed many hundreds of millions of years, as suggested by some solar system evolution models, collisions within the primordial small-body disk would have disrupted these relatively fragile binaries, leaving none to be captured in the Trojan population. Earlier dynamical instabilities would have left more binaries intact, increasing the likelihood that at least one would have been captured in the Trojan population. The team created new models that show that the existence of the Patroclus-Menoetius binary strongly indicates an earlier instability.

This early dynamical instability model has important consequences for the terrestrial planets, particularly regarding the origin of large impact craters on the Moon, Mercury and Mars that formed approximately 4 billion years ago. The impactors that made these craters are less likely to have been flung in from the outer regions of the Solar System. This could imply they were made by small-body leftovers of the terrestrial planet formation process.

Read more at Science Daily

Evolution of psychiatric disorders and human personality traits

VMAT1 (vesicular monoamine transporter 1) is encoded by the SLC18A1 gene, which is involved in transfer monoamises, such as dopamine and serotonin.

How and why human-unique characteristics such as highly social behavior, languages and complex culture have evolved is a long-standing question. A research team led by Tohoku University in Japan has revealed the evolution of a gene related to such human-unique psychiatric traits.

PhD candidate Daiki Sato and Professor Masakado Kawata have discovered SLC18A1 (VMAT1), which encodes vesicular monoamine transporter 1, as one of the genes evolved through natural selection in the human lineage. VMAT1 is mainly involved in the transport of neurochemicals, such as serotonin and dopamine in the body, and its malfunction leads to various psychiatric disorders. VMAT1 has variants consisting of two different amino acids, threonine (136Thr) and isoleucine (136Ile), at site 136.

Several studies have shown that these variants are associated with psychiatric disorders, including schizophrenia, bipolar disorder, anxiety, and neuroticism (a personality trait). It has been known that individuals with 136Thr tend to be more anxious and more depressed and have higher neuroticism scores. They showed that other mammals have 136Asn at this site but 136Thr had been favored over 136Asn during human evolution. Moreover, the 136Ile variant had originated nearly at the Out-of-Africa migration, and then, both 136Thr and 136Ile variants have been positively maintained by natural selection in non-African populations.

The study by Sato and Kawata indicates that natural selection has possibly shaped our psychiatric traits and maintained its diversity. The results provide two important implications for human psychiatric evolution. First, through positive selection, the evolution from Asn to Thr at site 136 on SLC18A1 was favored by natural selection during the evolution from ancestral primates to humans, although individuals with 136Thr are more anxious and have more depressed minds.

Second, they showed that the two variants of 136Thr and 136Ile have been maintained by natural selection using several population genetic methods. Any form of natural selection that maintains genetic diversity within populations is called "balancing selection." Individual differences in psychiatric traits can be observed in any human population, and some personality traits are also found in non-human primates. This suggests the possibility that a part of genetic diversity associated with personality traits and/or psychiatric disorders are maintained by balancing selection, although such selective pressure is often weak and difficult to detect.

From Science Daily

Large wind and solar farms in the Sahara would increase heat, rain, vegetation

Large-scale wind and solar installations in the Sahara would increase precipitation, a new study finds.

Wind and solar farms are known to have local effects on heat, humidity and other factors that may be beneficial -- or detrimental -- to the regions in which they are situated. A new climate-modeling study finds that a massive wind and solar installation in the Sahara Desert and neighboring Sahel would increase local temperature, precipitation and vegetation. Overall, the researchers report, the effects would likely benefit the region.

The study, reported in the journal Science, is among the first to model the climate effects of wind and solar installations while taking into account how vegetation responds to changes in heat and precipitation, said lead author Yan Li, a postdoctoral researcher in natural resources and environmental sciences at the University of Illinois.

"Previous modeling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales," Li said. "But the lack of vegetation feedbacks could make the modeled climate impacts very different from their actual behavior.

The new study, co-led with Eugenia Kalnay and Safa Motesharrei at the University of Maryland, focused on the Sahara for several reasons, Li said.

"We chose it because it is the largest desert in the world; it is sparsely inhabited; it is highly sensitive to land changes; and it is in Africa and close to Europe and the Middle East, all of which have large and growing energy demands," he said.

The wind and solar farms simulated in the study would cover more than 9 million square kilometers and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively.

"In 2017, the global energy demand was only 18 terawatts, so this is obviously much more energy than is currently needed worldwide," Li said.

The model revealed that wind farms caused regional warming of near-surface air temperature, with greater changes in minimum temperatures than maximum temperatures.

"The greater nighttime warming takes place because wind turbines can enhance the vertical mixing and bring down warmer air from above," the authors wrote. Precipitation also increased as much as 0.25 millimeters per day on average in regions with wind farm installations.

"This was a doubling of precipitation over that seen in the control experiments," Li said. In the Sahel, average rainfall increased 1.12 millimeters per day where wind farms were present.

"This increase in precipitation, in turn, leads to an increase in vegetation cover, creating a positive feedback loop," Li said.

Solar farms had a similar positive effect on temperature and precipitation, the team found. Unlike the wind farms, the solar arrays had very little effect on wind speed.

"We found that the large-scale installation of solar and wind farms can bring more rainfall and promote vegetation growth in these regions," Kalnay said. "The rainfall increase is a consequence of complex land-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land surfaces.

Read more at Science Daily