Spanking in developing countries does more harm than good, study suggests

Spanking may be increasingly harmful for children on a more global scale than previously known, a new University of Michigan study indicates.

Most research on how spanking affects children has involved studying families in high-income countries, such as the United States and Canada, but less was known about how spanking affects children in low- and middle-income countries -- or developing countries.

Spanking is one of the most common forms of child discipline used by parents worldwide.

The new international research used data collected by UNICEF in 62 countries -- representing nearly one-third of the world's countries -- and demonstrated that caregivers' reports of spanking were related to lower social development among 215,885 3- and 4-year-old children.

A parent or caregiver was asked in person if the child gets along well with other children; if the child hits, kicks or bites others; and if the child gets distracted easily. The question about spanking concerned the physical discipline used within the last month with the child or their sibling.

One-third of the respondents indicated they believed physical punishment is necessary to bring up, raise or educate a child properly. Among the children studied, 43 percent were spanked, or resided in a home where another child was spanked.

A child's social development suffered in both cases in which he or she was spanked or during times when a sibling had been spanked, the study showed.

"It appears that in this sample ... spanking may do more harm than good," said Garrett Pace, the study's lead author and a doctoral student of social work and sociology.

Pace also noted that "reductions in corporal punishment might do a great deal to reduce the burden of children's mental health and improve child development outcomes globally."

More effort to create policies that discourage spanking has occurred globally. In fact, 54 countries have banned the use of corporal punishment, which can only benefit children's well-being long term, Pace and colleagues said.

From Science Daily

Scientists explain how wombats drop cubed feces

Cubical feces in the wombat's intestine.

Wombats, the chubby and beloved, short-legged marsupials native to Australia, are central to a biological mystery in the animal kingdom: How do they produce cube-shaped poop? Patricia Yang, a postdoctoral fellow in mechanical engineering at the Georgia Institute of Technology, set out to investigate.

Yang studies the hydrodynamics of fluids, including blood, processed food and urine, in the bodies of animals. She was curious how the differences in wombats' digestive processes and soft tissue structures might explain their oddly shaped scat.

During the American Physical Society's Division of Fluid Dynamics 71st Annual Meeting, which will take place Nov. 18-20 at the Georgia World Congress Center in Atlanta, Georgia, Yang and her co-authors, Scott Carver, David Hu and undergraduate student Miles Chan, will explain their findings from dissecting the alimentary systems, or digestive tracts, of wombats.

"The first thing that drove me to this is that I have never seen anything this weird in biology. That was a mystery," said Yang. "I didn't even believe it was true at the beginning. I Googled it and saw a lot about cube-shaped wombat poop, but I was skeptical."

Yang and her co-authors studied the digestive tracts of wombats that had been euthanized following motor vehicle collisions in Tasmania, Australia. Carver, the biologist and Australian counterpart to the group of American mechanical engineers, supplied the wombat intestinal specimens.

Near the end of the intestine, they found that feces changed from liquidlike states to solid states made up of small, separated cubes. The group concluded that the varying elastic properties of wombats' intestinal walls allowed for the cube formation.

In the built world, cubic structures -- sugar cubes, sculptures, and architectural features -- are common, and produced by injection molding or extrusion. Cubes, however, are rare in the natural world. Currently, wombats are the only known species capable of producing cubes organically.

"We currently have only two methods to manufacture cubes: We mold it, or we cut it. Now we have this third method," Yang said. "It would be a cool method to apply to the manufacturing process -- how to make a cube with soft tissue instead of just molding it."

So, why do wombats poop cubes? Wombats pile their feces to mark their home ranges and communicate with one another through scent. They pile their feces in prominent places (e.g., next to burrows, or on logs, rocks and small raises) because they have poor eye sight. The higher and more prominently placed the pile of feces, the more visually distinctive it is to attract other wombats to smell and engage in communication. Therefore, it is important that their droppings do not roll away, and cube-shaped poop solves this problem.

Yang hopes that the group's research on wombats will contribute to current understandings of soft tissue transportation, or how the gut moves. She also emphasized that the group's research involved mechanical engineering and biology, and their findings are valuable to both fields. "We can learn from wombats and hopefully apply this novel method to our manufacturing process," Yang said. "We can understand how to move this stuff in a very efficient way."

Read more at Science Daily

Virtual reality simulation of a supermassive black hole

The black hole at the centre of our galaxy, Sagittarius A*, has been visualised in virtual reality for the first time. The details are described in an article published in the open access journal Computational Astrophysics and Cosmology.

Scientists at Radboud University, The Netherlands and Goethe University, Germany used recent astrophysical models of Sagittarius A* to create a series of images that were then put together to create a 360 degree virtual reality simulation of the black hole, that can be viewed on widely available VR consoles. The authors suggest that this virtual reality simulation could be useful for studying black holes.

Jordy Davelaar, corresponding author, said: "Our virtual reality simulation creates one of the most realistic views of the direct surroundings of the black hole and will help us to learn more about how black holes behave. Traveling to a black hole in our lifetime is impossible, so immersive visualizations like this can help us understand more about these systems from where we are."

The authors also suggest that the virtual reality simulation could help encourage the general public, including children, to take an interest in astrophysics.

Davelaar said: "The visualisations that we produced have a great potential for outreach. We used them to introduce children to the phenomenon of black holes, and they really learned something from it. This suggests that immersive virtual reality visualizations are a great tool to show our work to a broader audience, even when it involves very complicated systems like black holes."

Heino Falcke, Professor at Radboud University adds: "We all have a picture in our head of how black holes supposedly look, but science has progressed and we can now make much more accurate renderings -- and these black holes look quite different from what we are used to. These new visualisations are just the start, more to come in the future."

From Science Daily

New treatment to protect people with peanut allergies ready for FDA review

The final research results for a new treatment for protection against accidental exposure to peanut was presented today at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting and published in the New England Journal of Medicine. The results show it is possible for some people with peanut allergy to protect themselves from accidental ingestion by building up their tolerance to peanut over time.

"We're excited about the potential to help children and adolescents with peanut allergy protect themselves against accidentally eating a food with peanut in it," says allergist Stephen Tilles, MD, ACAAI past president, study co-author, and consulting advisor for Aimmune Therapeutics. "Our hope when we started the study was that by treating patients with the equivalent of one peanut per day, many would tolerate as much as two peanuts. We were pleased to find that two thirds of the people in the study were able to tolerate the equivalent of two peanuts per day after nine to 12 months of treatment, and half the patients tolerated the equivalent of four peanuts."

Study participants ranged in age from 4 to 55 years, most were 4 to 17, and all had peanut allergy. One third of the participants were given a placebo, while the remaining two-thirds were given peanut protein powder in increasing amounts until reaching the "maintenance dose" -- the dose they stayed on for the remainder of the study. The maintenance does was the equivalent of one peanut daily.

"This is not a quick fix, and it doesn't mean people with peanut allergy will be able to eat peanuts whenever they want," says allergist Jay Lieberman, MD, vice chair of the ACAAI Food Allergy Committee and study co-author. "But it is definitely a breakthrough. The hope would be to have a treatment available in the second half of 2019. If that happens, people who receive and are able to tolerate this treatment should be protected from accidental exposures."

All those in the study received peanut protein as part of an oral food challenge (OFC). A person in an OFC is given a very small dose of the food by mouth under the supervision of a board-certified allergist to test for a severe reaction. OFCs are considered the gold standard for testing food allergy.

"Reactions from the oral challenges at the end of the study were much milder than prior to treatment," says Dr. Tilles. "On average, the participants were able to tolerate a 100-fold higher dose of peanut at the end of the study than they did at the beginning. In addition, the symptoms caused by the 100-fold higher dose at the end of study were milder than the symptoms on the lower dose at the beginning of the study."

Facts about this pivotal study:

• More participants and more detailed data than all prior oral immunotherapy studies combined
• Fewer severe allergic reactions requiring epinephrine during oral food challenges
• Fewer side effects than anticipated -- e.g. only six percent dropped out of the study due to gastrointestinal side effects; Also, one-third of patients completed the study with no more than mild side effects along the way.
• 80 percent of participants successfully reached daily maintenance dose of the equivalent of one peanut.

Read more at Science Daily

Geneticist solves long-standing finch beak mystery

Princeton biologist Bridgett vonHoldt discovered that the 'mega' morph of the black-bellied seedcrackers (Pyrenestes ostrinus), a Cameroonian finch, appears to result from an additional evolutionary step after the evolution of the large- and small-beaked morphs.

Bridgett vonHoldt is best known for her work with dogs and wolves, so she was surprised when a bird biologist pulled her aside and said, "I really think you can help me solve this problem." So she turned to a mystery he'd been wrestling with for more than 20 years.

"I love a good challenge and especially working on new questions!" said vonHoldt, an assistant professor of ecology and evolutionary biology at Princeton. "I was presented with a new problem in an entirely new system, which was an incredible opportunity to explore how different ecologies could promote different evolutionary patterns."

The birder and biologist was Tom Smith, who has spent his career studying finches -- specifically, black-bellied seedcrackers (Pyrenestes ostrinus) -- in Cameroon and in his lab at the University of California-Los Angeles.

He and his colleagues have spent years investigating why some of these finches have small beaks while others have large beaks. Much of their original work identified differences in the hardness of the seeds they eat, a story quite similar to that of Darwin's finches. Smith, who is a professor at UCLA as well as the founding director of the Center for Tropical Research, established a breeding colony of these finches to understand the inheritance of beak size.

The result was startlingly and elegantly simple: Mendelian genetics, best known to generations of high school students through Punnett squares. The larger beak was the dominant trait, so two small-billed parents could only have small-billed offspring, but if either parent had a large bill, their offspring would have a mix of large and small bills, perfectly matching the 3:1 pattern predicted by Gregor Mendel centuries ago.

"You never get this!" said vonHoldt with a laugh. "Traits rarely show such a clean pattern of inheritance, especially traits that are very central to fitness in a wild population."

That Mendelian pattern was the key, said vonHoldt. With new technology to analyze the entire genome, combined with the Smith's years of ecological data and insights, they had all the pieces to find and understand the genes behind this mystery.

Smith had found the Mendelian pattern in these Cameroonian birds through observation, but he hadn't been able to identify the gene responsible for it. But when vonHoldt compared the genes of the large-beaked birds to those of their smaller-beaked counterparts, she found one stretch of DNA -- 300,000 base pairs, apparently inherited as a chunk -- that always varied between finches of large and small beak size. And right in the middle of that piece of chromosome was the gene IGF-1, familiar to vonHoldt from canine genetics.

"In dogs, this is a giant gene, literally and figuratively," she said. "It's a growth-factor gene. In dogs, if you change how it's expressed, with just a few genetic changes you can change a normal-sized dog into a dwarfed, teacup-sized dog."

The gene can affect a specific trait or a whole animal, depending where it's located on the genome and when it is expressed. "If this gene is expressed more, you expect a larger trait: a larger body, a larger foot, a larger ear, whatever it is controlling. It then is easy to imagine that with a small change to this gene, traits could very easily change in size or shape. We suspect this is the story here, with these beaks," vonHoldt said.

Smith and his colleagues had already determined that beak size affected diet -- whether a finch lived on large or small seeds -- but it didn't seem to have any impact on mate selection. "Females don't prefer males with a large beak, or vice-versa," said vonHoldt.

In these birds, the bill was the only trait changing size; large-beaked and small-beaked black-bellied seedcrackers are otherwise identical. But Smith also discovered a third morph of these finches, which he called the "mega" variety, with an even bigger bill and a larger overall body size.

After examining the genes, vonHoldt discovered that the "mega" is genetically distinct from the small- and large-beaked morphs. Not only does it carry two copies of the large allele -- like the large-beaked finches -- but it also has other chromosomal changes, apparently the product of an additional evolutionary step.

Read more at Science Daily

How electric fish got their big brains

Researchers from Washington University in St. Louis have mapped the regions of the brain in mormyrid fish in extremely high detail.

Helmet-heads of the freshwater fish world, African mormyrid fishes are known for having a brain-to-body size ratio that is similar to humans.

But there's actually a great deal of variation in the size of mormyrid brains. These differences provide an opportunity to look at what's behind the bulk.

Researchers from Washington University in St. Louis have mapped the regions of the brain in mormyrid fish in extremely high detail. In a new study published in the Nov. 15 issue of Current Biology, they report that the part of the brain called the cerebellum is bigger in members of this fish family compared to related fish -- and this may be associated with their use of weak electric discharges to locate prey and to communicate with one another.

The size finding in itself is not particularly surprising for those who follow this fish, said Bruce Carlson, professor of biology in Arts & Sciences. "It had almost become a truism," he said. In mormyrids, at least, the thinking went, "big brains mean big cerebellums."

Instead, the researchers are charged up about how their new measurements can help illuminate longstanding questions in neuroanatomy.

As brains get bigger, do all regions of the brain scale up in a predictable way? Or does natural selection act independently on separate regions of the brain -- such that certain parts of the brain become enlarged in animals that have extra reasons to use them?

"When you look at human brains, the cerebral cortex has become this giant part that has engulfed the other regions of the brain," said Kimberley V. Sukhum, first author of the new study, who recently completed her PhD in biology at Washington University. She works as a postdoctoral researcher at Washington University School of Medicine in St. Louis.

"We see something similar with the cerebellum in the mormyrids," Sukhum said. "But it wasn't known how this region had gotten so big -- or even if all of the species had a very big cerebellum."

There are more than 200 species of mormyrids. Some have been studied extensively because of their special electrosensory systems. Researchers long sought answers as to how these fish use electrical pulses for communication and way-finding. Other species in the mormyrid family have been largely ignored.

For this analysis, Carlson and Sukhum chose to compare individuals from six mormyrid species, one species that was considered a close relative, and three other distantly related fish species.

Sukhum and Carlson used micro-CT technology to collect full scans of the soft tissue of the fishes' brains, then painstakingly identified the landmarks that delineated distinct regions within them. The 3D maps they created allowed them to measure and compare the volume of individual regions of the brain with great precision.

Across all of the fish that they compared, they found that as total brain size increased, the sizes of individual regions within the brain also increased in a predictable fashion. However, with the mormyrids, they found that the size of the cerebellum could not be fully predicted by total brain size.

In other words, electric fish had significantly bigger cerebellums than fish with no zip. Electric fish also had bigger hindbrains than their related, non-electric cousins.

If one part of the brain can be shown to size up or size down independent of other parts of the brain, then neuroanatomists said this is an example of something called mosaic evolution. Mosaic shifts are thought to be relatively rare, and much of the current research on this topic is focused on identifying the kinds of situations in nature where such shifts occur.

"Here, we see the mosaic increases only in the mormyrids, and not in the outgroups," Sukhum said. "And one of the things that we see in the mormyrids and not the outgroups is the electrosensory system. There is a potential relationship between these two things."

Some of the mormyrids that they measured had extremely large brains -- up to three times bigger than the smallest-brained mormyrids in the study. Despite this difference in total size, there was no evidence of mosaic changes in the cerebellum within the group. This is evidence that mosaic shifts are not just the result of evolving a big brain. Instead, the shifts are likely related to the evolution of novel traits, such as the electrosensory system.

This study cannot say for sure why mormyrids have such big cerebellums -- only that they do.

Read more at Science Daily

Bursting bubbles launch bacteria from water to air

MIT researchers have found that bacteria can affect a bubble's longevity.

Wherever there's water, there's bound to be bubbles floating at the surface. From standing puddles, lakes, and streams, to swimming pools, hot tubs, public fountains, and toilets, bubbles are ubiquitous, indoors and out.

A new MIT study shows how bubbles contaminated with bacteria can act as tiny microbial grenades, bursting and launching microorganisms, including potential pathogens, out of the water and into the air.

In the study, published in the journal Physical Review Letters, the researchers found that bacteria can affect a bubble's longevity: A bacteria-covered bubble floating at the water's surface can last more than 10 times longer than an uncontaminated one can, persisting for minutes instead of seconds. During this time, the cap of the contaminated bubble thins. The thinner the bubble, the higher the number of droplets it can launch into the air when the bubble inevitably bursts. A single droplet, the researchers estimate, can carry up to thousands of microorganisms, and each bubble can emit hundreds of droplets.

"We discovered bacteria can manipulate interfaces in a manner that can enhance their own water-to-air dispersal," says Lydia Bourouiba, assistant professor of civil and environmental engineering and director of the Fluid Dynamics of Disease Transmission Laboratory.

Bourouiba's co-author on the paper is graduate student Stephane Poulain.

Something in the water

Bourouiba has spent the past several years meticulously generating, imaging, and characterizing clean, uncontaminated bubbles, with the goal of establishing a baseline of normal bubble behavior.

"We first had to understand the physics of clean bubbles before we could add organisms like bacteria to see what effect they have on the system," Bourouiba says.

As it happens, the researchers first noticed bacteria's effect somewhat by accident. The team was in the midst of moving to a new lab space, and in the shuffle, a beaker of water had been left out in the open. When the researcher used it in subsequent experiments, the results were not what the team expected.

"The bubbles produced from this water lived much longer and had a peculiar thinning evolution compared to that of typical clean water bubbles," Poulain says.

Bourouiba suspected the water had been contaminated, and the team soon confirmed her hypothesis. They analyzed the water and found evidence of bacteria that are naturally present indoors.

The juice effect

To directly study bacteria's effect on bubbles, the team set up an experiment in which they filled a column with a solution of water and various bacteria species, including E. coli. The researchers developed a system to generate bubbles with an air pump, one at a time, inside the column, in order to control the volume and size of each bubble. When a bubble rose to the surface, the team used high-speed imaging coupled with a range of optical techniques to capture its behavior, at the surface and as it burst.

The researchers observed that, once a bubble contaminated with E. coli made it to the water's surface, its own surface, or cap, immediately started to thin, mostly by draining back into the water, like a melting shell of chocolate. This behavior was similar to that of uncontaminated bubbles.

But the contaminated bubbles remained on the surface more than 10 times longer than uncontaminated bubbles. And after a critical period of time, the bacteria-laden bubbles started thinning much faster. Bourouiba suspected that it might not be the bacteria themselves, but what they secrete, that holds the bubble in place for longer.

"Bacteria are alive, and like anything alive, they make waste, and that waste typically is something that potentially could interact with the bubble's interface," Bourouiba says. "So we separated the organisms from their 'juice.'"

The researchers washed bacteria away from their secretions, then repeated their experiments, using the bacteria's secretions. Just as Bourouiba suspected, the bubbles containing the secretions alone lasted much longer than clean bubbles. The secretions, the group concluded, must be the key ingredient in extending a bubble's lifetime. But how?

Again, Bourouiba had a hypothesis: Bacterial secretions may be acting to reduce a bubble's surface tension, making it more elastic, more resistant to perturbations, and in the end, more likely to live longer on a water's surface. This behavior, she noted, was similar to surface-active compounds, or surfactants, such as the compounds in detergents that make soap bubbles.

To test this idea, the researchers repeated the experiments, this time by swapping out bacteria for common synthetic surfactants, and found that they too produced longer-lasting bubbles that also thinned dramatically after a certain time period. This experiment confirmed that bacteria's secretions act as surfactants extending the lifetime of contaminated bubbles.

The researchers then looked for an explanation for the drastic change in a contaminated bubble's rate of thinning. In clean bubbles, the thinning of the cap was mostly the result of drainage, as water in the cap mostly drains back into the fluid from which the bubble rose. Such bubbles live on the order of seconds, and their drainage speed continuously slows down as the bubble thins.

But if a bubble lasts past a critical time, evaporation starts playing a more dominant role than drainage, essentially shaving off water molecules from the bubble's cap. The researchers concluded that, if a bubble contains bacteria, the bacteria and their secretions, make a bubble last longer on a water's surface -- long enough that evaporation becomes more important than drainage in thinning the bubble's cap.

Read more at Science Daily

Climate, life and the movement of continents: New connections

Planktonic foraminifera, such as these collected in the Gulf of Mexico, form the base of many marine and aquatic food chains. Upon death, their skeletons settle on the seafloor to form sedimentary rock such as limestone and chalk. Pressed together in sufficient quantities, such sedimentary rock could have a lubricating effect on the movement of continental plates.

A new study by The University of Texas at Austin has demonstrated a possible link between life on Earth and the movement of continents. The findings show that sediment, which is often comprised from pieces of dead organisms, could play a key role in determining the speed of continental drift. In addition to challenging existing ideas about how plates interact, the findings are important because they describe potential feedback mechanisms between tectonic movement, climate and life on Earth.

The study, published Nov. 15 in Earth and Planetary Science Letters, describes how sediment moving under or subducting beneath tectonic plates could regulate the movement of the plates and may even play a role in the rapid rise of mountain ranges and growth of continental crust.

The research was led by Thorsten Becker, a professor at the UT Jackson School of Geosciences and research scientist at its Institute for Geophysics (UTIG), and Whitney Behr, a research fellow at the Jackson School and professor at ETH Zurich in Switzerland.

Sediment is created when wind, water and ice erode existing rock or when the shells and skeletons of microscopic organisms like plankton accumulate on the seafloor. Sediment entering subduction zones has long been known to influence geological activity such as the frequency of earthquakes, but until now it was thought to have little influence on continental movement. That's because the speed of subduction was believed to be dependent on the strength of the subducting plate as it bends and slides into the viscous mantle, the semi molten layer of rock beneath the Earth's crust. Continental movement is driven by one plate sinking under another so, in this scenario, the strength of the portion of the plate being pulled into the Earth's mantle (and the energy required to bend it) would be the primary control for the speed of the plate movement, with sediment having little effect.

However, prior research involving UTIG scientists had shown the subducting plates may be weaker and more sensitive to other influences than previously thought. This led researchers to look for other mechanisms that might impact plate velocity. They estimated how different types of rock might affect the plate interface ¬- the boundary where subducting plates meet. Subsequent modelling showed that rock made of sediment can create a lubricating effect between plates, accelerating subduction and increasing plate velocity.

This mechanism could set in motion a complex feedback loop. As plate velocity increases, there would be less time for sediment to accumulate, so the amount of subducting sediment would be reduced. This leads to slower subduction, which may allow for mountains to grow at plate boundaries as the force of the two plates running into each other causes uplift. In turn, erosion of those mountains by wind, water and other forces can produce more sediments which feed back into the subduction zone and restart the cycle by increasing the speed of subduction.

"The feedback mechanisms serve to regulate subduction speeds such that they don't 'runaway' with extremely fast velocities," said Behr.

Behr and Becker's new model also offers a compelling explanation for variations found in plate speed, such as India's dramatic northward acceleration some 70 million years ago. The authors propose that as India moved through equatorial seas teeming with life, an abundance of sedimentary rock formed by organic matter settling on the seafloor created a lubricating effect in the subducting plate. India's march north accelerated from a stately 5 centimeters per year (about 2 inches) to an eye-watering 16 centimeters per year (about 6 inches). As the continent accelerated the amount of sediment being subducted decreased and India slowed before finally colliding with Asia.

Behr and Becker suggest these feedback mechanisms would have been very different in the early Earth before the formation of continents and the emergence of life. Although their model does not examine the origins of these feedback mechanisms, it does raise compelling questions about the interaction between continental movement and life on Earth.

Read more at Science Daily

Overflowing crater lakes carved canyons across Mars

Jezero crater is a paleolake and potential landing site for NASA’s Mars 2020 rover mission to look for past life. The outlet canyon carved by overflow flooding is visible in the upper right side of the crater. Ancient rivers carved the inlets on the right side of the crater.

Today, most of the water on Mars is locked away in frozen ice caps. But billions of years ago it flowed freely across the surface, forming rushing rivers that emptied into craters, forming lakes and seas. New research led by The University of Texas at Austin has found evidence that sometimes the lakes would take on so much water that they overflowed and burst from the sides of their basins, creating catastrophic floods that carved canyons very rapidly, perhaps in a matter of weeks.

The findings suggest that catastrophic geologic processes may have had a major role in shaping the landscape of Mars and other worlds without plate tectonics, said lead author Tim Goudge, a postdoctoral researcher at the UT Jackson School of Geosciences who will be starting as an assistant professor at the school in 2019.

"These breached lakes are fairly common and some of them are quite large, some as large as the Caspian Sea," said Goudge. "So we think this style of catastrophic overflow flooding and rapid incision of outlet canyons was probably quite important on early Mars' surface."

The research was published Nov. 16 in the journal Geology. Co-authors include NASA scientist Caleb Fassett and Jackson School Professor and Associate Dean of Research David Mohrig.

From studying rock formations from satellite images, scientists know that hundreds of craters across the surface of Mars were once filled with water. More than 200 of these "paleolakes" have outlet canyons tens to hundreds of kilometers long and several kilometers wide carved by water flowing from the ancient lakes.

However, until this study, it was unknown whether the canyons were gradually carved over millions of years or carved rapidly by single floods.

Using high-resolution photos taken by NASA's Mars Reconnaissance Orbiter satellite, the researchers examined the topography of the outlets and the crater rims and found a correlation between the size of the outlet and the volume of water expected to be released during a large flooding event. If the outlet had instead been gradually whittled away over time, the relationship between water volume and outlet size likely wouldn't hold, Goudge said.

In total, the researchers examined 24 paleolakes and their outlet canyons across the Red Planet. One of the paleolakes examined in the study, Jezero Crater, is a potential landing site for NASA's Mars 2020 rover mission to look for signs of past life. Goudge and Fassett proposed the crater as a landing site based on prior studies that found it held water for long periods in Mars' past.

While massive floods flowing from Martian craters might sound like a scene in a science fiction novel, a similar process occurs on Earth when lakes dammed by glaciers break through their icy barriers. The researchers found that the similarity is more than superficial. As long as gravity is accounted for, floods create outlets with similar shapes whether on Earth or Mars.

"This tells us that things that are different between the planets are not as important as the basic physics of the overflow process and the size of the basin," Goudge said. "You can learn more about this process by comparing different planets as opposed to just thinking about what's occurring on Earth or what's occurring on Mars."

Although big floods on Mars and Earth are governed by the same mechanics, they fit into different geological paradigms. On Earth, the slow-and-steady motion of tectonic plates dramatically changes the planet's surface over millions of years. In contrast, the lack of plate tectonics on Mars means that cataclysmic events -- like floods and asteroid impacts -- quickly create changes that can amount to near permanent changes in the landscape.

Read more at Science Daily

Kilogram, ampere, kelvin and mole redefined

The International Prototype of the Kilogram (IPK) is held in an underground vault at the International Bureau of Weights and Measures (BIPM), located in Sèvres, near Paris. Following the decision to redefine the SI kilogram starting 20th May 2019, the definition of the kilogram will no longer be based on the physical artefact called the International Prototype but rather on a constant of physics, as are the other seven base units of the SI. The redefinition of the kilogram marks the end of artefacts used to define our measurement units.

Today, in a landmark decision, representatives from 60 countries voted to redefine the International System of Units (SI), changing the world's definition of the kilogram, the ampere, the kelvin and the mole, forever.

The decision, made at the General Conference on Weights and Measures in Versailles, France, which is organised by the International Bureau of Weights and Measures (BIPM), means that all SI units will now be defined in terms of constants that describe the natural world. This will assure the future stability of the SI and open the opportunity for the use of new technologies, including quantum technologies, to implement the definitions.

The changes, which will come into force on 20 May 2019, will bring an end to the use of physical objects to define measurement units.

The definition of the kilogram for more than 130 years, the International Prototype of the Kilogram (IPK), a cylinder of a platinum alloy stored at the BIPM in France, will now be retired. It will be replaced by the Planck constant -- the fundamental constant of quantum physics. While the stability of the IPK could only be confirmed by comparisons with identical copies, a difficult and potentially inaccurate process, the Planck constant is ready for use everywhere and always.

"The SI redefinition is a landmark moment in scientific progress," said Martin Milton, Director, International Bureau of Weights and Measures (BIPM). "Using the fundamental constants we observe in nature as a foundation for important concepts, such as mass and time, means that we have a stable foundation from which to advance our scientific understanding, develop new technologies and address some of society's greatest challenges."

"Today marks the culmination of decades of work by measurement scientists around the world, the significance of which is immense," said Barry Inglis, Director of the International Committee for Weights and Measures. "We will now no longer be bound by the limitations of objects in our measurement of the world, but have universality accessible units that can pave the way to even greater accuracy, and even accelerate scientific advancement."

The new definitions impact four of the seven base units of the SI: the kilogram, ampere, kelvin and mole; and all units derived from them, such as the volt, ohm and joule.

• The kilogram -- will be defined by the Planck constant (h)
• The ampere -- will be defined by the elementary electrical charge (e)
• The kelvin -- will be defined by the Boltzmann constant (k)
• The mole -- will be defined by the Avogadro constant (NA)

Although the size of these units will not change (a kilogram will still be a kilogram), the four redefined units will join the second, the metre and the candela to ensure that the set of SI base units will continue to be both stable and useful. The revised SI will maintain its relevance by facilitating technical innovations. Just as the redefinition of the second in 1967 provided the basis for technology that has transformed how we communicate across the globe, through GPS and the internet, the new changes will have wide-reaching impact in science, technology, trade, health and the environment, among many other sectors.

From Science Daily