Earth

The history of our planet has been written, among other things, in the periodic reversal of its magnetic poles. Scientists at the Weizmann Institute of Science propose a new means of reading this historic record: in ice. Their findings, which were recently reported in Earth and Planetary Science Letters, could lead to a refined probing ice cores and, in the future, might be applied to understanding the magnetic history of other bodies in our solar system, including Mars and Jupiter's moon Europa.

The idea for investigating a possible connection between ice and Earth's magnetic history arose far from the source of the planet's ice - on the sunny isle of Corsica, where Prof. Oded Aharonson of the Institute's Earth and Planetary Sciences Department, was attending a conference on magnetism. More specifically, the researchers there were discussing the field known as paleo-magnetism, which is mostly studied through flakes magnetic minerals that have been trapped either in rocks or cores drilled through ocean sediments. Such particles get aligned with the Earth's magnetic field at the time they are trapped in place, and even millions of years later, researchers can test their magnetic north-south alignment and understand the position of the Earth's magnetic poles at that distant time. The latter is what gave Aharonson the idea: If small amounts of magnetic materials could be sensed in ocean sediments, maybe they could also be found trapped in ice and measured. Some of the ice frozen in the glaciers in places like Greenland or Alaska is many millennia old and is layered like tree rings. Ice cores drilled through these are investigated for signs of such things as planetary warming or ice ages. Why not reversals in the magnetic field as well?

The first question that Aharonson and his student Yuval Grossman who led the project had to ask was whether it was possible that the process in which ice forms in regions near the poles could contain a detectable record of magnetic pole reversals. These randomly-spaced reversals have occurred throughout our planet's history, fueled by the chaotic motion of the liquid iron dynamo deep in the planet's core. In banded rock formations and layered sediments, researchers measure the magnetic moment - the magnetic north-south orientations - of the magnetic materials in these to reveal the magnetic moment of the Earth's magnetic field at that time. The scientists thought such magnetic particles could be found in the dust that gets trapped, along with water ice, in glaciers and ice sheets.

The research team built an experimental setup to simulate ice formation such as that in polar glaciers, where dust particles in the atmosphere may even provide the nuclei around which snowflakes form. The researchers created artificial snowfall by finely grinding ice made from purified water, adding a bit of magnetic dust, and letting it fall though a very cold column that was exposed to a magnetic field, the latter having an orientation controlled by the scientists. By maintaining very cold temperatures - around 30 degrees Celsius below zero, they found they could generate miniature "ice cores" in which the snow and dust froze solidly into hard ice.

"If the dust is not affected by an external magnetic field, it will settle in random directions which will cancel each other out," says Aharonson. "But if a portion of it gets oriented in a particular direction right before the particles freeze in place, the net magnetic moment will be detectible."

To measure the magnetism of the "ice cores" they had created in the lab, the Weizmann scientists took them to Hebrew University in Jerusalem, to the lab of Prof. Ron Shaar, where a sensitive magnetometer installed there is able to measure the very slightest of magnetic moments. The team found a small, but definitely detectible magnetic moment that matched the magnetic fields applied to their ice samples.

"The Earth's paleo-magnetic history has been studied from the rocky record; reading it in ice cores could reveal additional dimensions, or help assign accurate dates to the other findings in those cores," says Aharonson. "And we know that the surfaces of Mars and large icy moons like Europa have been exposed to magnetic fields. It would be exciting to look for magnetic field reversals in ice sampled from other bodies in our solar system."

"We've proved it is possible," he adds. Aharonson has even proposed a research project for a future space mission involving ice core sampling on Mars, and he hopes that this demonstration of the feasibility of measuring such a core will advance the appeal of this proposal.

Sophia Antipolis, 29 June 2020: Sugar consumption is linked with larger fat deposits around the heart and in the abdomen, which are risky for health. That's the finding of a study published today in the European Journal of Preventive Cardiology, a journal of the European Society of Cardiology (ESC).1

"When we consume too much sugar the excess is converted to fat and stored," said study author Ms. So Yun Yi, a PhD student at the University of Minnesota School of Public Health. "This fat tissue located around the heart and in the abdomen releases chemicals into the body which can be harmful to health. Our results support limiting added sugar intake."

Excess sugar consumption is a worldwide problem. The six countries with the highest sales of sugary drinks per capita are Chile, Mexico, Argentina, Peru, the US, and Saudi Arabia. The demand for sugar is expected to increase in Asia, Africa, and Russia.

This observational study examined both sugar-sweetened beverages (such as soft drinks, fruit drinks, energy drinks) and sugar added to foods and beverages for sweetness (for example when cooking or in processed foods). The researchers analysed the association between long-term sugar consumption and fat stores around the heart and other organs.

Data were obtained from Coronary Artery Risk Development in Young Adults (CARDIA), an ongoing cohort study in the US that includes centres in Alabama, California, Illinois, and Minnesota. A total of 3,070 healthy participants aged 18 to 30 were included in this study.

Food and beverage intakes were measured three times over a 20-year period (1985 to 2005). After 25 years (in 2010) computed tomography (CT) scans of the chest and abdomen were performed to measure fat volumes in the abdomen and around the heart.

The researchers found that sugar intake over the 20-year period was related to fat volumes later in life. Higher intakes of both sugar-sweetened beverages and added sugar were related to greater fat stores around organs in a stepwise fashion.

"Our findings provide more evidence that consuming too much added sugar and sugary drinks is related to a higher amount of fat tissue," said study author Dr. Lyn Steffen of the University of Minnesota School of Public Health. "And, we know that fat deposits are connected with higher risks of heart disease and diabetes."

She advised reducing the amount of added sugar consumed each day. "Have water instead of sugary drinks and choose healthier snacks over foods rich in added sugar like cakes," she said. "Read food labels to check the amount of added sugar in what you are buying. Look for ingredients like syrups, glucose, fructose, sucrose, and maltose. Being more aware of hidden sugar will help you cut back."

Dr. Steffen said: "On top of our individual efforts, governments, food manufacturers, restaurants, schools, and workplaces have a role to play in increasing consumer awareness of the sugar content in foods and beverages and offering healthier alternatives."

A new mathematical model for predicting variations in solar irradiance has been developed at Uppsala University. It may help to promote more efficient use of electricity from solar energy. In tests of various data models, the model proved capable of making highly reliable forecasts, and emerged as the best for this purpose in some respects. The results have now been published in two articles in the journal Solar Energy.

As clouds pass overhead, solar power generation from a photovoltaic system fluctuates from one minute to the next. Local producers of their own solar energy (for a single property, for example) wishing want to adjust their electricity use according to supply may need to know, in detail, how the amount of sunlight is changing. Forecasts of solar irradiance (the amount of solar radiation reaching a given surface, measured in watts per square metre, W/m2) may be a way of achieving greater control of solar power production.

Project leader Joakim Munkhammar of the Department of Civil and Industrial Engineering at Uppsala University explains.

"Our 'MCM model', as it's called, serves to predict what will happen in the next minute, hour or day, based on what usually follows a particular solar irradiance level. This model has a simple design, is easy to train and use, and provides surprisingly accurate solar irradiance forecasts."

The model, presented to the scientific community last year, is based on a "hidden Markov model" - that is, a statistical model for recognition and probabilistic forecasting of processes and patterns. The MCM (Markov chain mixture) distribution model divides solar irradiance into levels and calculates the probabilities of sunlight in the next and subsequent time periods being at the various levels. On this basis, it is possible to forecast when, and between which levels, sunlight will vary, and to compare the forecasts with actual observations to see how well the former match reality.

The model has now been tested by both scientists who have worked on it previously and other researchers. This has included test runs to compare the model with several other models. In one study, in which the model and five established benchmark models (used for comparison, to evaluate the relative performance of new models) were tested, the new MCM model yielded the most reliable forecasts, especially for the near future.

The Uppsala researchers now hope it will be feasible to use their model to control technical systems.

"We look forward to working with other scientists and companies on testing the model with real physical systems, such as those for battery energy storage. We're going to try and boost the cost-effectiveness of storage systems by adjusting the charge, based on forecasts of local solar power generation," Munkhammar says.

Using the large synchrotron radiation facility SPring-8 in Japan, a collaboration of researchers from Kumamoto University, the University of Tokyo, and others from Japan and France have precisely measured the density of liquid iron under conditions similar to those at Earth's outer core: 1,000,000 atm and 4,000 degrees C. Accurate density measurements of liquid iron under such extreme conditions is very important for understanding the chemical make-up of our planet's core.

The Earth has a solid metal inner core and a liquid metal outer core located some 2,900 km (1,800 mi) below the surface, both of which are under very high pressures and temperatures. Since the main component of the outer core is iron, and its density is considerably lower than that of pure iron, it was thought to contain a large amount of light elements like hydrogen and oxygen. Identifying the type and amount of these light elements will allow for a better understanding of the origin of the Earth, specifically the materials that made up the Earth and the environment at the core when it separated from the mantle. However, this first requires an accurate measurement of the density of pure liquid iron at extreme pressure and temperature similar to the molten core so densities can be compared.

As pressure rises, the melting point of iron also rises, which makes it difficult to study the density of liquid iron under ultra-high pressure. Previous high-pressure liquid iron density measurements claimed that it was about 10% higher than the density of liquid iron under core conditions, but the shock compression experiments used were assumed to have a large error.

The current work improves upon these measurements by using the high-intensity X-ray at the SPring-8 facility to measure the X-ray diffraction of liquid iron under ultra-high pressures and high temperatures, and applies a novel analytical method to calculate the liquid density. Additionally, the sound speed profile of the liquid was measured under extreme conditions up to 450,000 atm. Data was collected at various temperatures and pressures then combined with previous shock-wave data to calculate density for conditions over the entire Earth's core.

Currently, the best way to estimate the density of the Earth's outer core is from seismic observations. Comparing the outer core density to the experimental measurements in this study finds that pure iron is about 8% more dense than that of the Earth's outer core. Oxygen, which has been regarded as a major impurity in the past, cannot explain the density difference, suggesting the presence of other light elements. This revelation is a big step towards estimating the chemical composition of the core--a first-class problem in Earth Science.

"Worldwide, many attempts to measure the density, speed of sound, and structure of liquids under ultrahigh pressures using laser-heated diamond cells have been made for over 30 years, but none have been successful so far," said Dr. Yoichi Nakajima, one of the main members of the research collaboration. "We expect that the technological innovations achieved in this study will dramatically accelerate research on liquids under high pressures. Eventually, we believe that this will deepen our understanding of the liquid metallic core and magma deep within the Earth and other rocky planets."

The sweeping pink salt lakes across Australia's interior are all that remain of the lush green places three species of pink flamingos once thrived the outback.

Some much larger than flamingos now found in Africa and other parts of the world, Australian flamingos enjoyed a range of freshwater habitats for about 25 million years, Flinders University researchers say.

After several Ice Ages and millions of years, the last Australian flamingos died out about 140,000 years ago as the inland lakes disappeared due to climate change.

"The once verdant interior of the country dried out during the last two Ice Ages," says Associate Professor Trevor Worthy, an expert in fossil birds of Australia and New Zealand.

"Feeding on tiny crustaceans, which gave them the familiar pink colour, these birds evolved to live in shallow lakes and breed during the seasonal blooms of algae and zooplankton. But when all the lakes dried up, the flamingos were doomed."

A complete scientific list of all fossil birds in Australia has been published in Transactions of the Royal Society of South Australia, attracting considerable interest from researchers.

While Australia has about 936 species of living birds, the work published by Flinders University Associate Professor Worthy and ARC DECRA bird researcher Dr Jacqueline Nguyen includes nearly 100 bird species known from fossils.

"Flamingos are just some of the bird diversity lost in Australia's history," says Associate Professor Worthy, who hopes the list will stimulate future study of ancient extinct birds.

"What we show is that there is much yet to learn about the evolution of Australia's birds through more work on the fossils described so far.

"It shows we know very little about the evolution of important Australian groups such as raptors, pigeons, parrots and songbirds. In fact, there is much yet to learn about land birds generally," says Associate Professor Worthy.

Dr Nguyen says: "Our understanding of Australian birds is enriched by the fossil record, which offers a unique window into past bird diversity."

"This list covers the amazing range of fossil birds that once lived in Australia, such as flamingos and giant penguins, but it also reveals the gaps in our knowledge. We see it as a challenge to fill those gaps."

Creating social bonds is essential for our health and well-being. In a new study conducted at Center for Music in the Brain at Aarhus University, Denmark, postdoctoral researcher Jan Stupacher and colleagues showed that music provides a unique context for social bonding.

The findings, which were published in Scientific Reports suggest that when moving together with music, synchronous movements between individuals increase social closeness.

Jan Stupacher explains:

"There is something sublime and affectionate in moving together with people in the crowd of a concert or in a music club. Even just watching people synchronize their movements in dance or when making music together can give us a feeling of harmony and affiliation. A friend just left the following comment on the paper, 'My best friends are those whom I met at dance parties and electronic music festivals around the globe!

The time spent together dancing and laughing creates such a strong bond and feeling of comm(unity).' This is in line with our general conclusion: The unique context provided by music can strengthen social bonds that connect people with different backgrounds - especially if these people move together in time with the beat and enjoy the same music."

Stupacher and colleagues were especially interested in the questions how cultural familiarity with music and personal musical taste affect social bonding when moving in synchrony or asynchrony with another person. They created an online video-paradigm, which allowed investigating these effects with participants from all over the world. In three individual experiments, they showed that the influence of movement synchrony on social bonding is less affected by what music we are familiar with but more affected by what music we enjoy.

When the context-providing music was more enjoyed, social closeness increased strongly with a synchronized partner, but only weakly with an asynchronized partner. This interaction effect did not occur for musical familiarity: When the music was more familiar, social closeness was higher independent of movement synchrony.

Center leader, Professor Peter Vuust concludes:

"The current study goes to the heart of why human beings are musical creatures in the first place. It shows that the reason why music connects us is that it combines bodily synchronization with positive emotions. It indicates that if there is an evolutionary advantage of music, it is probably due to its ability to synchronize our movements, emotions and brains."

A research team lead by Ludmilla Morozova Roche at Umeå University, Sweden, has provided the mechanistic insight into protein co-aggregation in Alzheimer's disease. The templating mechanism of S100A9 amyloids on Aβ fibrillar surfaces during co-aggregation process was revealed by synergy of biophysical methods including charge detection mass spectrometry, microscopy, kinetic and microfluidic analyses.

Amyloid formation is of the key clinical significance since this process is involved in numerous neurodegenerative diseases such as Alzheimer's, Parkinson's and others. These diseases affect millions of the aging population world-wide. Often it is difficult to draw the line between these diseases or they may occur simultaneously, which is known as disease comorbidity.

While the amyloid formation process was studied extensively, little is known about the specific mechanisms of co-aggregation of different amyloid species together, underlying the comorbidity of the diseases. In Alzheimer's disease, the amyloid-neuroinflammatory cascade is manifested in co-aggregation of Aβ with proinflammatory S100A9 protein, which leads to intracellular and extracellular amyloid assembly, amyloid plaque depositions and cellular toxicity.

Deciphering the interactions between proinflammatory S100A9 protein and Aβ42 peptide in Alzheimer's disease is fundamental since inflammation plays a central role in the disease onset. Here the researchers use innovative charge detection mass spectrometry (CDMS) together with biophysical techniques to provide mechanistic insight into the co-aggregation process and differentiate amyloid complexes at a single particle level.

Combination of mass and charge distributions of amyloids together with reconstruction of the differences between them and detailed microscopy reveals that co-aggregation involves templating of S100A9 fibrils on the surface of Aβ42 amyloids. Kinetic analysis further corroborates that the surfaces available for the Aβ42 secondary nucleation are diminished due to coating by S100A9 amyloids, while the binding of S100A9 to Aβ42 fibrils is validated by a microfuidic assay.

The researchers demonstrate that synergy between CDMS, microscopy, kinetic and microfuidic anayses opens new directions in interdisciplinary research.

The long-running study on aging and brain health at the University of Kentucky's Sanders-Brown Center on Aging Alzheimer's Disease Center has once again resulted in important new findings - highlighting a complex and under-recognized form of dementia. The work was recently published in the Journal of the American Medical Association (JAMA): Neurology.

"One of the things that we've learned in the last decade or so is that a lot of people that we think have dementia from Alzheimer's disease, actually don't. There are other brain diseases that cause the same kind of symptoms as Alzheimer's, including some that we only recently figured out existed," said Erin Abner an associate professor at the University of Kentucky's Sanders-Brown Center on Aging (SBCoA) and College of Public Health, who helped lead the recent study.

Abner collaborated with several of her colleagues at SBCoA for the study, which used brain autopsy data from 375 older adults within the University of Kentucky Alzheimer Disease Center Brain Bank. This work builds on the work done last year by Dr. Pete Nelson and his team to discover another form of dementia caused by TDP-43 proteinopathy now known as LATE.

Abner refers to misfolded TDP-43 protein, which was discovered in 2006, as the "newest brain bad guy." She says although TDP-43 exists normally in a non-disease causing form, it is seen in multiple debilitating diseases in addition to LATE, including ALS and frontotemporal dementia. She says as she and the team at SBCoA reviewed clinical and brain autopsy data for research participants, they noticed there were significantly more people than expected that had not only Alzheimer's pathology but also pathology indicating Lewy bodies (alpha synuclein), and the "newest brain bad guy" - TDP-43.

"They had every neurodegeneration causing pathology that we know about. There was not a name for this, so we came up with one: quadruple misfolded proteins, or QMP," stated Abner.

The group then obtained more data to conduct a study of how often QMP occurred and what that meant for the participant with QMP. The study found that about 20% of the participants with dementia had QMP, and their dementia was the most severe.

"This is not great news, because it means that even if we could completely cure Alzheimer's disease, we still have to deal with TDP-43 and alpha synuclein, and they are common in old age. But, we have to understand exactly what we are up against as we try to stop dementia. We still have so much to learn," said Abner.

Russian scientists from Far Eastern Federal University (FEFU), G. B. Elyakov Pacific Institute of Bioorganic Chemistry (PIBOC FEB RAS), and A.V. Zhirmunsky National Scientific Center for Marine Biology (NSCMB FEB RAS) have discovered four new steroid substances which target cells of human breast cancer, and colorectal carcinoma. They were extracted from the starfish Ceramaster patagonicus, a Kuril basin seabed dweller. A related article appears in Marine Drugs.

The discovery made due to the joint expedition of scientists of FEFU and Far Eastern Branch of Russian Science Academy (FEB RAS) to the Kuril Islands at the "Academic Oparin" research vessel.

Four new compounds belong to non-typical derivatives of polar steroids with residual tails of fatty acids in the molecular structure. According to scientists, these compounds may be responsible in the body of starfish for the delivery of nutrients from the digestive tract to peripheral cells, acting alike bile acids in the human stomach. Previously, only one such compound was isolated from starfish.

In the study, scientists point out a pronounce anticancer effect of the unusual molecules. At the same time, researchers suggest that, due to their steroid nature, one can potentially consider such substances from starfish as blockers of neurodegenerative diseases (Alzheimer's disease, etc.), since they help nerve cells survive distress like, for example, low levels of oxygen and glucose.

"Importantly, the new steroid compounds from starfish curb the reproduction of cancer cells in non-toxic concentrations. That gives a hope that new substances will not kill healthy body cells, and makes a promise for further study and testing," says Timofey Malyarenko, Ph.D., associate professor of the Department of Bioorganic Chemistry and Biotechnology, FEFU School of Natural Sciences, Deputy Director for Science and Senior Researcher at Laboratory of Chemistry of Marine Natural Compounds in PIBOC FEB RAS. "It is interesting that these compounds had been found almost by accident when I was looking for new lipid molecules or fats of marine origin in the starfish extract. During the separation of substances on chromatographic plates (TLC), curious spots were detected. Having studied them, we established the structures of four new derivatives of polar steroids with fatty acids. There are five of them in the world now."

According to the scientist, the next step of the study could be the production of molecules with increased therapeutic properties based on steroid compounds. In addition, it is probable to scrutinize the new compounds to reveal the most active molecules responsible for the drug effect. It would give the opportunity to look for similar compounds in other types of starfishes. Potentially, these future substances will be even more effective.

FEFU University runs a priority project for a comprehensive study of the biological resources of the World Ocean. Among the aims of the project is to pick new biologically active marine substances and cast them for the roles of drugs of the future.

In biology, phylogenetic trees represent the evolutionary history and diversification of species - the "family tree" of Life. Phylogenetic trees not only describe the evolution of a group of organisms but can also be constructed from the organisms within a particular environment or ecosystem, such as the human microbiome. In this way, they can describe how this ecosystem evolved and what its functional capabilities might be.

Now, researchers have presented a new analysis of the patterns generated by phylogenetic trees, suggesting that they reflect previously hypothesized connections between evolution and ecology. The study was led by Swanlund Professor of Physics Nigel Goldenfeld, who also leads the Biocomplexity Group at the Carl R. Woese Institute for Genomic Biology at the University of Illinois at Urbana-Champaign. The other members of the team were graduate student Chi Xue and former undergraduate student Zhiru Li, now at Stanford University. Their findings were published in a recent article in the journal Proceedings of the National Academy of Science, titled "Scale-invariant topology and bursty branching of evolutionary trees emerge from niche construction."

The most familiar phylogenetic tree of all life on Earth uses genes from the essential cellular ribosomal machinery to represent species. By comparing the differences between the molecular sequences of the same genes on different organisms, researchers can deduce which organisms were descended from others. This idea led to the mapping-out of the evolutionary history of life on Earth and the discovery of the third domain of life by Carl R. Woese and collaborators in 1977.

Real phylogenetic trees are complex branching structures, reflecting the pattern of speciation as new mutants emerge from a species. The branching structures are complex, but it is possible to characterize them in terms of how balanced they are and other statistical features reflecting the topology of the tree. The simplest characterization is to look at each branching node on the tree: does it split into two branches of exactly the same length or are the branches unequal in length? The former is said to be balanced while the latter unbalanced.

Despite the complexity of trees, there is a consistent mathematical pattern in topological structure across evolutionary time, one that is self-similar or fractal in nature. Using a minimal representation of evolution, the researchers showed how this fractal structure reflects the indelible imprint of the interplay between ecological and evolutionary processes. Minimal models of nature do not aim to be overly realistic but instead are constructed to capture the most important ingredients of a process in a way that makes simulation and mathematical analysis easy.

Goldenfeld's work frequently uses minimal models in order to explain generic aspects of complex biological and physical phenomena that are insensitive to precise details. Other aspects of complex phenomena cannot be described well in this way, but physical patterns such as self-similarity in space are known to be describable using minimal modeling approaches.

"Thus, it seemed reasonable to try this approach to describe self-similarity in time too" Goldenfeld said.

"We set off to study the topological property of the phylogenetic tree and ended up with an extra 'fruit of explanation" for the tree's special character,'" Xue said.

The study revolved around a concept in evolutionary ecology known as niche construction, first proposed about 40 years ago. In niche construction, organisms modify their environment, thereby creating new ecological niches in the ecosystem and changing the environment. In turn, these new niches affect the overall evolutionary trajectory of the organisms that share the environment. The end result is that evolution and the environment are coupled closely together. The idea that evolution is not occurring on a purely static environmental background is controversial, despite being intuitively appealing. Their findings add to the existing body of work by identifying the long term effects of niche construction in a way that can be detected by modern genomics and phylogenetic tree construction.

In the work reported here, researchers simulated organisms and associated to them a niche value that described their interaction with their environment. Those organisms with a large niche value contained a large number of ways to adapt to their environment and ultimately led to their survival while those with small niche values were less resilient.

"In our model, we relate the niche positively to the speciation probability, in the sense that an organism with a large niche can likely diversify successfully," Xue said. "During the phylogenetic tree evolution, when two daughter nodes emerge from their parent, they get their niches partially from inheriting and partially from construction."

Researchers showed that species which run out of niche space can no longer branch or speciate. Mathematically, this was represented as a so-called absorbing boundary condition on the node representing this species.

"Its sister node likely still diversifies as long as that niche is still positive, but the two sister nodes are no longer symmetric and the tree becomes unbalanced," Xue explained. "We demonstrated that the absorbing boundary is crucial to generate the fractal structure of the tree and that the niche construction guarantees that some nodes will reach the boundary."

The researchers used a simplified model of niche construction and were able to recapitulate the fractal scaling in the tree topology. Their calculations used methods adopted from a completely different field of science: the physics of phase transitions. An example of a phase transition is when a material such as iron becomes magnetic as its temperature is lowered. The magnetism emerges gradually once the temperature falls below a critical value.

Goldenfeld explained how this unusual analogy works: "Very close to this critical temperature, a magnet also is fractal or self-similar: it is structured into nested regions of magnetic and non-magnetic domains. This nesting or self-similar structure in space is reminiscent of the nesting or self-similar structure of bifurcating tree branches in time." Using computer simulations and the mathematics of phase transitions, the research team was able to demonstrate how the fractal scaling of the tree topology emerges.

"Our model has a small number of components and assumes simple mathematical form and yet, it generates the power-law scaling with the right exponent that is observed in actual biological data," Xue explained. "It's simply amazing to see how much a minimal model can do."

"We were able to reproduce not only the power-law behavior but also a non-trivial exponent that's very close to reality," Liu said. "In other words, the simulated trees are not only scale-invariant but also realistic in a way."

In addition to describing the fractal topology of phylogenetic trees, the model also accounted for the patterns of evolutionary clades previously documented to occur in microbial communities by Illinois Professor of Plant Biology James O'Dwyer, an ecologist trained in theoretical physics like Goldenfeld.

"It was especially gratifying to be able to gain some insight into James' earlier discovery, using a conceptual toolkit that came from statistical physics," Goldenfeld commented. "This work exemplifies the way in which powerful and unexpected results can arise from trans-disciplinary research, painstaking data analysis and minimal modeling."

The presence of niche construction creates a significant footprint in the evolutionary trajectory that cannot be eliminated, even across long time scales. The idea that niche construction -- which is based on a much shorter time scale -- emerges as a long-term memory in phylogenetic trees may surprise some people. Indeed, Liu adds that this "scale-interference" is also a hallmark of phase transitions, where the spacing between atoms in a magnetic crystal on the scale of Angstroms can influence the material properties on the scale of centimeters.

"When I learned about the idea of scale-interference in Nigel's physics class on phase transitions three years ago, I wasn't expecting any of the following: joining his group, applying this idea and solving a biological problem," said Liu. "Now I'm glad that I didn't doze off during that lecture."

The fact that people are living longer lives represents one of the crowning achievements of the last century, but also requires careful planning on the part of governments. A new IIASA study investigated the prevalence of activity limitations among older adults in 23 low- and middle-income countries, to help policymakers prepare for the challenges associated with the world's aging population.

By 2050, the world's population aged 60 years and older is expected to reach 2 billion, of which 80% will live in low- and middle-income countries. We know that not all people age the same way, as how healthy older people are very much depends on their physical and social environments, the health and social support systems in their countries, as well as on their personal characteristics. The effect is that some 80 year-olds may have physical and mental capacities similar to many 30 year-olds, while others may experience significant declines in their physical and mental health, even at a much younger age. Policymakers need comprehensive information around how people are aging in their countries and how much support they would need when they start to experience physical limitations related to old age, to enable them to plan for future public health infrastructure and services to provide for older people's needs.

While European countries and the US have been conducting extensive surveys on aging and health for many years, there is very limited national information available for low- and middle-income countries. According to the authors of the new study published in Scientific Reports, only a few studies focus on low-income countries, and even fewer use comparable health measures. Using data from the World Health Survey and the UN World Population Prospects, the study for the first time makes projections of older adults with severe activity limitations for low- and middle-income countries.

"Just like high-income countries, low- and middle-income countries face a continuous increase in their share of older adults. Up to now, we however did not know much about how people age in these countries. In this study, we wanted to answer questions like whether we should expect many unhealthy older adults. How do people in low- and middle-income countries age? And, how many older adults with severe activity limitations, that most likely will not be able to live an independent life, can we expect in the next 30 years?" explains Daniela Weber, lead author of the study and a researcher in the IIASA World Population Program.

Applying an innovative methodology developed at IIASA, the researchers specifically looked at health status based on the activity limitations of older adults across the world and forecasted the share of men and women over the age of 50 with severe activity limitations in 23 low- and middle-income countries. The results revealed constant prevalence rates of older adults with severe activity limitations in low- and middle-income countries for the next 30 years, but overall, the authors say that they were surprised to observe similar health trends in these countries than in high-income countries. In addition, the study's projections show large variation in the proportion of older adults with physical limitations across the 23 countries investigated. This can be attributed to disparities in health conditions in the respective countries, but also to differences in cultural peculiarities of reporting (such as it being more common to complain in some cultures than in others), and historical perceptions of health. With that said, all 23 countries are facing considerable demographic changes that will require policy interventions.

"The significance of population aging and its global implications cannot be overstated. It is important to raise awareness, not only about global issues pertaining to population aging, but also the importance of rigorous cross-national research and policy dialogue that will help address the challenges and opportunities of an aging world. This study contributes to the body of research that will help policymakers prepare for a future marked by the challenges associated with the continued growth of the world's aging population. Preparing financially for longer lives and finding ways to reduce aging-related disability are likely to become national and global priorities," concludes study author and IIASA researcher, Sergei Scherbov.

PHILADELPHIA - Office visits for ongoing prescribing of skeletal muscle relaxant drugs tripled from 2005 to 2016, according to a new study from researchers in the Perelman School of Medicine at the University of Pennsylvania.

Moreover, in 2016, nearly 70 percent of patients prescribed muscle relaxants were simultaneously prescribed an opioid -- a combination that has the potential to cause dangerous interactions. The researchers also found that muscle relaxants were prescribed disproportionately to older adults during this time period, despite national guidelines warning that this class of drugs should almost always be avoided in patients who are 65 and older. The results were published today in JAMA Network Open.

"There are few studies on the short-term efficacy and safety of skeletal muscle relaxants, and almost no data on their long-term effects, so it is very concerning that patients, and particularly older adults, are using these drugs for an extended period of time," said Charles E. Leonard, PharmD, MSCE, an assistant professor of Epidemiology. "Providers seem to be reaching for them despite incomplete information on their potential benefits and risks."

Skeletal muscle relaxants are drugs that were approved years ago for short-term treatment of muscle spasms and back pain, and are used today, without good evidence, to treat chronic pain and other conditions. Recommendations generally limit the use of these drugs to a maximum of three weeks, since they have not been shown to work for muscle spasms beyond that duration, and they can cause serious side effects including falls, fractures, vehicle crashes, abuse, dependence, and overdose. Due to these risks, muscle relaxants should be avoided altogether in elderly patients, according to guidelines from the American Geriatrics Society.

Despite these concerns, Leonard and his colleagues hypothesized that the growing opioid epidemic may have led clinicians to prescribe muscle relaxants as an alternative to opioids for long-term pain management.

To measure national trends in muscle relaxant prescribing, the researchers analyzed publicly-available 2005-2016 data from the National Ambulatory Medical Care Survey. NAMCS is a U.S.-based annual survey of non-federally funded office-based physicians engaged in direct patient care. The researchers examined the total number of visits per year, and stratified counts by the muscle relaxant agent, whether the drug was newly prescribed or continued therapy, as well as the race, ethnicity, and sex of the patient, and the region of the visit.

From 2005 to 2016, the number of office visits resulting in new muscle relaxant prescriptions remained stable at approximately 6 million per year, while office visits for continued muscle relaxant drug therapy tripled -- from 8.5 million in 2005 to 24.7 million in 2016. Worryingly, older adults accounted for 22.2 percent of all muscle relaxant visits in 2016, even though this group accounted for just 14.5 percent of the U.S. population. Also of concern, in 2016, 67 percent of the continued muscle relaxant visits also recorded therapy with an opioid. The U.S. Food and Drug Administration warns against use of co-prescribing of these medications, because of the risk of serious side effects, including slowed or difficult breathing, and death.

"For older adults, I think the message should be to avoid using muscle relaxants, especially when we consider the side effects and increased risk of falls and fractures, and to find alternatives for pain management," said the study's first author Samantha Soprano, MPH, a research coordinator and student in Penn's Master of Behavioral and Decision Sciences program.

Leonard added that, in addition to potential adverse effects, muscle relaxants may not be any more effective in managing pain than medications like Tylenol or Advil. Past studies examining muscle relaxants found they were more efficacious than a placebo, but they were not compared to other therapies. Further research is needed to determine more detailed information about the effects of muscle relaxants, particularly when used for longer periods of time, since their use is so widespread, Leonard said. Additionally, doctors need better, safer options for managing patients' pain.

"Muscle relaxants' place in therapy is really limited. Based on most guidelines, they're normally reserved as second- or third-line therapies," Leonard said. "Our findings suggest that prescribers may be reaching for these drugs sooner than that."

Ancestors of a distinctive pollinating bee found across Australia probably originated in tropical Asian countries, islands in the south-west Pacific or greater Oceania region, ecology researchers claim.

Describing the likely dispersal corridor for the ancestral lineage of the bee genus Homalictus will help understand the social evolution of the vibrant halictine bees, South Australian, Czech and PNG researchers say in a new paper.

It follows earlier research* connecting the origin of other Australian bees to the polar south or Antarctica routes millions of years ago - helping to explain the diversity and complexity of natural ecosystems and their resilience or susceptibility during periods of climate change.

Ecologists are hopeful that the diverse origins of native bees are giving them an edge in withstanding and adapting further to climate change.

"Homalictus bees are a leading generalist plant pollinator across Australia and as far north as southern China," says Flinders University PhD candidate, photographer and native bee expert James Dorey.

"Our study highlights the importance of the habitat and ecology of tropical regions, including Papua New Guinea and the Fijian islands, for our endemic species and shows us how these bees might have expanded across the Pacific and possibly higher latitudes of Southeast Asia."

SA Museum senior researcher Associate Professor Mark Stevens says the ongoing research aims to better understand the origin and radiation of insects and other animals, help environmental management during changing climates and mitigate the effects of further human expansion and habitat destruction.

"Many species historically evolved under difference climatic conditions and those different histories may determine how they will cope with new climates," he says.

"As climates change, species that have narrow thermal tolerances that are unable to adapt either track their preferred climate by moving, or become extinct. We see this in our studies on tropical bees and also in the studies of Antarctic biodiversity."

"What has not been fully appreciated is the movement of bees in the southern hemisphere that included Antarctica as a likely dispersal corridor before it became the glacial continent that it is today."

Antarctica was the crossroads between South America, Africa and Australia as the supercontinent of Gondwana was breaking up. The last landmass connections between Australia and Antarctica finished about 35 million years ago while the interchange with Asia began about 20 million years ago.

In contrast to the colourful tropical varieties, SA researchers have previously explored the origins of the cooler adapted and less colourful Exoneurine allodapine bees, believed to have originated in Africa but dispersed to Australia about 42-34 million years ago from Antarctica when there was still a land bridge connection to Tasmania.

Co-author on the online Homalictus paper, Associate Professor Mike Schwarz says Australia has the most unusual bee fauna in the world, resulting from three major events - the gradual breakup of Gondwana, then a period when the bees evolved in "splendid isolation", long before humans arrived.

"Thirdly, there was a northern influx of species from tropical Asia as the Australian continent collided with Asia. "Australia's complex systems diversity if a key ingredient for survival of our species," Flinders Associate Professor Schwarz says.

"Hopefully, the diversity of our native bees will make them more resilient to future climate scenarios, which will be critical for agriculture in a changing world.

A new analysis of 16 years of publicly accessible health data on 68.5 million Medicare enrollees provides broad evidence that long-term exposure to fine particles in the air - even at levels below current EPA standards - leads to increased mortality rates among the elderly. Based on the results of five complementary statistical models, including three causal inference methods, the researchers estimate that if the EPA had lowered the air quality standard for fine particle concentration from 12 μg/m3 down to the WHO guideline of 10 μg/m3, more than 140,000 lives might have been saved within one decade. "Our findings provide the strongest evidence to date that current national air quality standards aren't sufficiently protective of Americans' health," said corresponding author Francesca Dominici. "Now, in the middle of a pandemic that attacks our lungs and makes us unable to breathe, it is irresponsible to roll back environmental policies," she added. The new study is likely to inform national discussions around updating air quality standards, for example, the National Ambient Air Quality Standards by the EPA.

A number of studies have documented a strong correlation between long-term exposure to fine particulate and greater human mortality, but some concern has remained about the causal nature of the evidence, and whether it is sufficient to inform revisions to air quality standards. Some scientists argue that modern causal inference methods can provide such evidence, using the right data. "Causal inference can quantify and visualize how close our data are to approximating a randomized controlled study, the gold standard for assessing causation," said the study's lead author Xiao Wu. Analyzing a massive dataset through five distinct approaches, including two traditional statistical methods and three causal inference methods, Wu and colleagues derived broad evidence consistent with a causal link between long-term particulate exposure and mortality. Modeling a 10 μg/m3 decrease of fine particle concentration between 2000 and 2016 resulted in a 6% to 7% decrease in mortality risk. Based on their model results, the researchers estimated that more than 140,000 lives might have been saved if the current U.S. standard for fine particle concentration had been lowered to 10 μg/m3 between 2007 and 2016. The authors emphasize the urgent need to modify particulate concentration levels to help protect elderly individuals with respiratory diseases living in polluted areas.

Dust storms from Africa's Saharan Desert traveling across the Atlantic Ocean are nothing new, but the current dust storm has been quite expansive and NASA satellites have provided a look at the massive June plume. NASA-NOAA's Suomi NPP satellite showed the blanket of dust had moved over the Gulf of Mexico and extended into Central America and over part of the eastern Pacific Ocean.

NASA uses satellites and other resources to track aerosol particles made of desert dust, smoke, and volcanic ash. The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image while the Ozone Mapping and Profiling Suite (OMPS) Nadir-Mapper (NM) instrument aboard the Suomi-NPP satellite provided absorbing aerosol index values. The OMPS index indicates the presence of light absorbing aerosol particles (ultraviolet (UV)-absorbing particles in the air) such as desert dust. The absorbing aerosol index is related to both the thickness and height of the aerosol layer.

The Absorbing Aerosol Index is useful for identifying and tracking the long-range transport of volcanic ash from volcanic eruptions, smoke from wildfires or biomass burning events and dust from desert dust storms. These aerosol particals can even be tracked over clouds and areas covered by snow and ice.

Colin Seftor, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., created imagery from the Suomi NPP OMPS absorbing aerosol index and visible imagery from the VIIRS instrument He said that on June 23 and 24 the dust plume had moved completely over Mexico's Yucatan Peninsula, up through the Gulf of Mexico and into southern Texas. "At that point, the situation becomes more complicated because the absorbing aerosol index signal seen further north into Texas, Oklahoma, Nebraska, etc., is probably a mix of dust and smoke from the numerous fires burning in the southwest U.S. You can also see that the dust traveled over Central America and out into the Eastern Pacific Ocean."

On June 25, an animation that combined OMPS aerosol index and VIIRS visible imagery from NASA/NOAA's Suomi NPP satellite was created at NASA Goddard showing the movement the Saharan dust cloud from June 15 to 25, 2020,. The animation showed the dust plume streamed from Africa's west coast over the Atlantic into the Caribbean Sea and up through the Gulf of Mexico over some of the Gulf states.

Aerosol particles absorb and scatter incoming sunlight, which reduces visibility and increases the optical depth. Aerosol particles have an effect on human health, weather and the climate. Aerosol particles are produced from many events including human activities such as pollution from factories and natural processes such as smoke from fires, dust from dust storms, sea salt from breaking waves, and volcanic ash from volcanoes. Aerosol particles compromise human health when inhaled by people with asthma or other respiratory illnesses. Aerosol particles also affect weather and climate by cooling or warming the earth as well as enhancing or preventing cloud formation.

On June 18, NASA's Earth Observatory noted the thickest parts of the plume appeared to stretch about 2,500 kilometers (1,500 miles) across the Atlantic Ocean. By June 24, the plume extended over 5,000 miles.

Dust from Africa can affect air quality as far away as North and South America if it is mixed down to ground level. But dust can also play an important ecological role, such as, fertilizing soils in the Amazon and building beaches in the Caribbean. The dry, warm, and windy conditions associated with Saharan Air Layer outbreaks from Africa can also suppress the formation and intensification of tropical cyclones.

"While Saharan dust transport across the ocean to the Americas is not uncommon, the size and strength of this particular event is quite unusual," Seftor said. "Also, if you look off the coast of Africa you can see yet another large cloud coming off the continent, continuing to feed the long chain of dust traveling across the Atlantic."