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New tools to systematically build cooperation: Theory of repeated games

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When what we want as individuals clashes with what is best for the group, we have a social dilemma. How can we overcome these dilemmas, and encourage people to cooperate, even if they have reason not to? In a paper released today in Nature, Christian Hilbe and Krishnendu Chatterjee of the Institute of Science and Technology Austria (IST Austria), together with Martin Nowak of Harvard and Stepan Simsa of Charles University, have shown that if the social dilemma that individuals face is dependent on whether or not they work together, cooperation can triumph. This finding was the result of a new type of framework that they introduced — one that extends the entire theory of repeated games. Moreover, as their work pinpoints the ideal conditions for fostering cooperation, they have provided tools to systematically build cooperation.

The tragedy of the commons: if we can (ab)use a public good without seeing negative consequences, we will — without consideration of others or the future. We see examples of this in our daily lives, from climate change and forest depletion down to the stack of dirty dishes in the office kitchen. In game theory, scientists have used repeated games — repeated interactions where individuals face the same social dilemma each time — to understand when individuals choose to cooperate, i.e. their strategies. However, these games have always kept the value of the public resource constant, no matter how players acted in the previous round — something that does not reflect reality of the situation.

In their new framework, Hilbe, Simsa, Chatterjee, and Nowak consider repeated games in which cooperation does not only affect the players’ present payoffs, but also which game they face in the next round. “Repeated games have been studied intensely for over 40 years, and significant new developments are rare — especially such simple ones,” says Martin Nowak. “This addition actually extends the whole theory of repeated games, as a fixed environment is a special case of our new framework.”

When they explored the new model, the scientists found that this dependence on players’ actions could greatly increase the chance that players cooperate — provided the right conditions were in place. “Our framework shows which kinds of feedback are most likely to lead to cooperation,” says first author Christian Hilbe. These include, for instance, how quickly the resource degrades or how easy it is to return to a more valuable state. “Using this knowledge, you can design systems that maximize cooperation, or create an environment that encourages people to work together,” he adds. For example, these ideas could even be implemented by a business or corporation, to create a work community that encourages working together.

 

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Plasma-spewing quasar shines light on universe’s youth, early galaxy formation

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Carnegie’s Eduardo Bañados led a team that found a quasar with the brightest radio emission ever observed in the early universe, due to it spewing out a jet of extremely fast-moving material.

Bañados’ discovery was followed up by Emmanuel Momjian of the National Radio Astronomy Observatory, which allowed the team to see with unprecedented detail the jet shooting out of a quasar that formed within the universe’s first billion years of existence.

The findings, will allow astronomers to better probe the universe’s youth during an important period of transition to its current state.

Quasars are comprised of enormous black holes accreting matter at the centers of massive galaxies. This newly discovered quasar,  is one of a rare breed that doesn’t just swallow matter into the black hole but also emits a jet of plasma traveling at speeds approaching that of light. This jet makes it extremely bright in the frequencies detected by radio telescopes. Although quasars were identified more than 50 years ago by their strong radio emissions, now we know that only about 10 percent of them are strong radio emitters.

What’s more, this newly discovered quasar’s light has been traveling nearly 13 billion of the universe’s 13.7 billion years to reach us here in Earth. P352-15 is the first quasar with clear evidence of radio jets seen within the first billion years of the universe’s history.

“There is a dearth of known strong radio emitters from the universe’s youth and this is the brightest radio quasar at that epoch by an order of magnitude.”

“This is the most-detailed image yet of such a bright galaxy at this great distance.”

The Big Bang started the universe as a hot soup of extremely energetic particles that were rapidly expanding. As it expanded, it cooled and coalesced into neutral hydrogen gas, which left the universe dark, without any luminous sources, until gravity condensed matter into the first stars and galaxies. About 800 million years after the Big Bang, the energy released by these first galaxies caused the neutral hydrogen that was scattered throughout the universe to get excited and lose an electron, or ionize, a state that the gas has remained in since that time.

It’s highly unusual to find radio jet-emitting quasars such as this one from the period just after the universe’s lights came back on.

“The jet from this quasar could serve as an important calibration tool to help future projects penetrate the dark ages and perhaps reveal how the earliest galaxies came into being.”

Gene-editing technique cures genetic disorder in utero

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Researchers at Carnegie Mellon University and Yale University have for the first time used a gene editing technique to successfully cure a genetic condition in a mouse model. Their findings,  present a promising new avenue for research into treating genetic conditions during fetal development.

An estimated 8 million children are born each year with severe genetic disorders or birth defects. Genetic conditions can often be detected during pregnancy using amniocentesis, but there are no treatment options to correct these genetic conditions before birth.

“Early in embryonic development, there are a lot of stem cells dividing at a rapid pace. If we can go in and correct a genetic mutation early on, we could dramatically reduce the impact the mutation has on fetal development or even cure the condition,” said Danith Ly, professor of chemistry in Carnegie Mellon’s Mellon College of Science.

In this study, the researchers used a peptide nucleic acid-based gene editing technique that they had previously used to cure beta thalassemia, a genetic blood disorder that results in the reduced production of hemoglobin, in adult mice.

Peptide nucleic acids are synthetic molecules that combine a synthetic protein backbone with the nucleobases found in DNA and RNA.

Their technique uses an FDA-approved nanoparticle to deliver PNA molecules paired with donor DNA to the site of a genetic mutation. When the PNA-DNA complex identifies a designated mutation, the PNA molecule binds to the DNA and unzips its two strands. The donor DNA binds with the faulty DNA and spurs the cell’s DNA repair pathways into action, allowing it to correct the error.

In the current study, the researchers used a technique similar to amniocentesis to inject the PNA complex into the amniotic fluid of pregnant mice whose fetuses carried a mutation in the beta-globin gene that causes beta thalassemia.

With just one injection of the PNA during gestation, the researchers were able to correct 6 percent of the mutations. This 6 percent correction was enough to cause dramatic improvements in the mice’s symptoms of beta thalassemia ¬- and enough for the mice to be considered cured. Mice that were treated using PNA while in utero had levels of hemoglobin that were within the normal range, less spleen enlargement and increased survival rates.

The researchers also noted that there were no off-target effects from the treatment, a finding that might suggest this method would be preferable over other gene editing techniques like CRISPR/Cas9, which can erroneously damage off-target DNA.

“CRISPR is much easier to use, which makes it ideal for laboratory research. But the off-site errors make it less useful for therapeutics.”  “The PNA technique is more ideal for therapeutics. It doesn’t cut the DNA, it just binds to it and repairs things that seem unusual. We looked at 50 million samples and couldn’t find one offsite error when we used our PNA gene editing technique.”

The researchers believe that their technique might be able to achieve even higher success rates if they can administer it multiple times during gestation. They also hope to see if their technique can be applied to other conditions.

This work was made possible by the support of the DSF Charitable Foundation, who has donated $7 million to CNAST, enabling the center to engage in fundamental research aimed at developing synthetic chemistry solutions for the diagnosis and treatment of disease.

 

 

Senolytic drugs reverse damage caused by senescent cells in mice

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Injecting senescent cells into young mice results in a loss of health and function but treating the mice with a combination of two existing drugs cleared the senescent cells from tissues and restored physical function. The drugs also extended both life span and health span in naturally aging mice.

A research found that injecting even a small number of senescent cells into young, healthy mice causes damage that can result in physical dysfunction. The researchers also found that treatment with a combination of dasatinib and quercetin could prevent cell damage, delay physical dysfunction, and, when used in naturally aging mice, extend their life span.

“This study provides compelling evidence that targeting a fundamental aging process — in this case, cell senescence in mice — can delay age-related conditions, resulting in better health and longer life,” “This study also shows the value of investigating biological mechanisms which may lead to better understanding of the aging process.”

Many normal cells continuously grow, die, and replicate. Cell senescence is a process in which cells lose function, including the ability to divide and replicate, but are resistant to cell death. Such cells have been shown to affect neighboring ones because they secrete several pro-inflammatory and tissue remodeling molecules. Senescent cells increase in many tissues with aging; they also occur in organs associated with many chronic diseases and after radiation or chemotherapy.

Senolytics are a class of drugs that selectively eliminate senescent cells. In this study, Kirkland’s team used a combination of dasatinib and quercetin (D+Q) to test whether this senolytic combination could slow physical dysfunction caused by senescent cells. Dasatinib is used to treat some forms of leukemia; quercetin is a plant flavanol found in some fruits and vegetables.

To determine whether senescent cells caused physical dysfunction, the researchers first injected young (four-month-old) mice with either senescent (SEN) cells or non-senescent control (CON) cells. As early as two weeks after transplantation, the SEN mice showed impaired physical function as determined by maximum walking speed, muscle strength, physical endurance, daily activity, food intake, and body weight. In addition, the researchers saw increased numbers of senescent cells, beyond what was injected, suggesting a propagation of the senescence effect into neighboring cells.

To then analyze whether a senolytic compound could stop or delay physical dysfunction, researchers treated both SEN and CON mice for three days with the D+Q compound mix. They found that D+Q selectively killed senescent cells and slowed the deterioration in walking speed, endurance, and grip strength in the SEN mice.

In addition to young mice injected with senescent cells, the researchers also tested older (20-month-old), non-transplanted mice with D+Q intermittently for 4 months. D+Q alleviated normal age-related physical dysfunction, resulting in higher walking speed, treadmill endurance, grip strength, and daily activity.

Finally, the researchers found that treating very old (24- to 27-month-old) mice with D+Q biweekly led to a 36 percent higher average post-treatment life span and lower mortality hazard than control mice. This indicates that senolytics can reduce risk of death in old mice.

“This is exciting research,” said Felipe Sierra, Ph.D., director of NIA’s Division of Aging Biology. “This study clearly demonstrates that senolytics can relieve physical dysfunction in mice. Additional research will be necessary to determine if compounds, like the one used in this study, are safe and effective in clinical trials with people.”

The researchers noted that current and future preclinical studies may show that senolytics could be used to enhance life span not only in older people, but also in cancer survivors treated with senescence-inducing radiation or chemotherapy and people with a range of senescence-associated chronic diseases.

 

Snooze mobiles: How vibrations in cars make drivers sleepy

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New research has found the natural vibrations of cars make people sleepier, affecting concentration and alertness levels just 15 minutes after drivers get behind the wheel.

With about 20 per cent of fatal road crashes involving driver fatigue, researchers from RMIT University in Melbourne, Australia, hope their findings can be used by manufacturers to improve car seat designs to help keep drivers awake.

Professor Stephen Robinson said the effects of physical vibration on drivers were not well understood, despite growing evidence that vibration contributes to feelings of sleepiness.

“We know 1 in 5 Australians have fallen asleep at the wheel and we know that drowsy driving is a significant issue for road safety,” Robinson said.

“When you’re tired, it doesn’t take much to start nodding off and we’ve found that the gentle vibrations made by car seats as you drive can lull your brain and body.

“Our study shows steady vibrations at low frequencies — the kind we experience when driving cars and trucks — progressively induce sleepiness even among people who are well rested and healthy.

“From 15 minutes of getting in the car, drowsiness has already begun to take hold. In half an hour, it’s making a significant impact on your ability to stay concentrated and alert.

“To improve road safety, we hope that future car seat designs can build in features that disrupt this lulling effect and fight vibration-induced sleepiness.”

Led by chief investigators Associate Professor Mohammad Fard and Professor Stephen Robinson, the research team tested 15 volunteers in a virtual simulator that replicates the experience of driving on a monotonous two-lane highway.

The simulator was set up on a platform that could be vibrated on different frequencies, with the volunteers tested twice — once with vibrations at low frequencies (4-7Hz) and once with no vibration.

The tiredness induced by vibration makes it psychologically and physiologically harder to perform mental tasks, so the body’s nervous system activates to compensate, leading to changes in the heartbeat.

By looking at the volunteers’ heart rate variability (HRV), researchers were able to gain an objective measure of how drowsy they were feeling as the 60-minute test progressed.

Within 15 minutes of starting the vibrating test, volunteers were showing signs of drowsiness. Within 30 minutes, the drowsiness was significant, requiring substantial effort to maintain alertness and cognitive performance.

The drowsiness increased progressively over the test, peaking at 60 minutes.

Associate Professor Mohammad Fard said more work was needed to build on the findings and examine how vibrations affected people across different demographics.

“We want to study a larger cohort, particularly to investigate how age may affect someone’s vulnerability to vibration-induced drowsiness as well as the impact of health problems such as sleep apnea,” he said.

“Our research also suggests that vibrations at some frequencies may have the opposite effect and help keep people awake.

“So we also want to examine a wider range of frequencies, to inform car designs that could potentially harness those ‘good vibrations’.”

The cross-disciplinary RMIT research team brought together expertise in human body vibration and automotive engineering, sleep physiology and virtual reality from the schools of Engineering, Health and Biomedical Sciences, and Media and Communication.

Marine protected areas often expensive and misplaced

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Many marine protected areas are often unnecessarily expensive and located in the wrong places.

The University of Queensland was part of research which found protected areas missed many unique ecosystems, and have a greater impact on fisheries than necessary.

A collaboration with the University of Hamburg, Wildlife Conservation Society and The Nature Conservancy assessed the efficiency of marine protected areas, which now cover 16 per cent of national waters around the world.

UQ’s School of Biological Sciences researcher Professor Hugh Possingham said international marine preservation targets are falling short.

“International conservation targets such as the United Nation’s Sustainable Development Goals call for protection of at least 10 per cent of all the world’s oceans and all marine ecosystems.”

“Despite a tenfold increase in marine protected areas since the year 2000 — a growth of 21 million square kilometres — half of all marine ecosystems still fall short of the target, with 10 ecosystems entirely unprotected.”

The researchers assessed whether the expansion had been cost efficient — measuring potential earnings lost from fisheries — and effectively focused.

The University of Hamburg’s Dr Kerstin Jantke, who led the research, said that marine protected areas could have been far more efficient with greater planning.

“With a more strategic approach at the inception of global conservation targets in 1982, the marine protected area network could be a third smaller, cost half as much, and meet international targets by protecting 10 per cent of every ecosystem,” she said.

“It is clearly in the interests of nations to start strategic planning as early as possible to avoid costly imbalanced reserve systems.”

Nations will negotiate new conservation targets for 2020-2030 at a United Nations meeting next year in China.

“We urge governments to take note and be tactical from the outset, delivering better outcomes for nature conservation, but also saving them a lot of money.”

Local interventions boost coral’s resilience to bleaching

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Local conservation actions, like rounding up predatory snails, can significantly boost the resilience of corals to climate-induced bleaching.

The study, comes at a time when scientists are deeply divided over whether local efforts to protect and manage coral reefs are enough to help stem the global tide of thermal bleaching that’s decimating corals worldwide as ocean temperatures continue to warm.

To test whether local actions can make a difference, the Duke-led team focused on one threat to reefs that is often controlled by local managers — populations of coral-eating animals like snails and starfish that have become too abundant.

“At high densities, these coral-eating animals, or ‘corallivores’, can cause low-grade but chronic stress to corals. Some of them are like Dracula, constantly sucking the energetic reserves out of corals and leaving them less equipped to deal with harsh environmental conditions like extreme warm temperatures and bleaching,” said Elizabeth Shaver, a 2018 doctoral graduate of Duke’s Nicholas School of the Environment, who is now a coral restoration scientist with The Nature Conservancy’s Reef Resilience Program.

To get a global sense of how managers deal with this threat, the researchers surveyed more than 30 coral reef management agencies worldwide, finding that many agencies reduce local corallivore populations in their sites. The researchers then mimicked managers by manually removing a voracious and common coral-eating snail from corals in the Florida Keys during a three-month spike in ocean temperatures in 2014. That warmup caused widespread coral bleaching across much of the eastern Caribbean and Gulf of Mexico.

The researchers focused their efforts on brain corals, which were found in a survey of six corals reefs in the Florida Keys to be particularly susceptible to predation by the snail.

“The idea was to see if removing these snails helped corals withstand and recover from warm temperatures and bleaching compared with corals that had average or naturally high densities of snails. And it did.”

“When snails were removed, corals experienced only 50 percent bleaching. Corals that still had high snail densities experienced near 100 percent,” Shaver said.

“We found that if a coral experienced only mild to moderate bleaching, as they did when snails were removed, it recovered almost completely,” said Brian Silliman, Rachel Carson Associate Professor of Marine Conservation Biology at Duke’s Nicholas School of the Environment.

“But if it experienced severe bleaching like the corals with high snail densities, tissue recovery was reduced by more than 80 percent,” Silliman said. “Some of these corals completely died, turning into algae-covered underwater basketballs. Removing or reducing the populations of snails played an important role in determining these outcomes.”

The new findings challenge several recent large-scale analyses arguing that local impacts and management have little effect in protecting reefs from climate-induced bleaching, Silliman said.

“Tens of millions of dollars have been invested in local coral reef conservation over the last 40 years. But more and more people are now saying we should end this approach and instead put most of our money into global efforts to reduce greenhouse gas emissions because there’s no evidence that local actions are making enough of a difference,” he said.

“These new findings reopen the discussion and provide a ray of hope for corals by showing that local interventions do make a difference.”

“Very few local interventions have been tested for their ability to enhance coral reef resilience,” Shaver said. “We found one simple solution by reducing coral predation stress, which can be done through removals or possibly in marine protected areas where studies show coral-eating invertebrates are naturally less abundant.”

The findings may also be important because the world’s climate is projected to continue changing even if carbon emissions were drastically reduced today.

“We need conservation dollars for both global and local efforts,” said Shaver, “so we can identify other resilience-enhancing approaches and arm local managers with tools to protect their reefs and resources.”