Earth

Fish kills are a recurring phenomenon in lakes suffering from oxygen depletion. Often the kills are triggered by factors like an algae bloom, but now a new study reports on a new, climate-related cause of fish kills.

A grave example is reported from a lake in Denmark. In 2018, Denmark was hit by extreme summer drought and temperatures in May, June and July were 3 degrees higher than the average for the previous 30 years. At the same time, an average of only 27 mm of rain fell compared to normally 56 mm.

The lake, called Lake Filsø, received no rainfall until a thunderstorm with heavy rain blew across the lake on July 28, delivering 22 mm in only a few hours.

Resets an entire ecosystem

'Huge amounts of water flowed from the catchment into the lake and brought with it huge amounts of organic material. This cocktail led to massive fish kills in the lake. Events like this are dramatic and can completely reset an entire ecosystem,' explains biologist and Associate Professor Theis Kragh from the University of Southern Denmark.

A few days after the heavy rainfall, 1,203 dead pike were found in the lake. A month later, only a single pike was caught in the gill nets. The stocks have never recovered, and this year the researchers released 8,000 pike fry and 350 kg of spawning stock biomass of perch to help the stocks return.

'And we will follow up with more pike breeding in the future. The tragedy is that the oxygen depletion only lasted four days. On day five, oxygen levels were normal again, but then the fish had died,' he says.

How could it happen?

The reason why heavy rainfall can lead to massive fish kills is this:

When rain falls, it runs through ditches and drainage pipes and ends up in the lake. On its way, it picks up a lot of labile organic matter from the soil; leaves, mud, and partially degraded organic matter.

When all this organic matter is flushed out into the lake, it becomes a target of hungry bacteria. When the bacteria consume the organic matter, they use oxygen and they take that oxygen from the water. This causes oxygen depletion in the lake, and the fish die.

'Lake Filsø is not the only lake to have experienced this, and it will happen to other lakes. Until now, we have considered extreme drought followed by heavy rain as a 20- or 100-year event, but climate change is a reality now and we should rather consider it a 5- or 10-year event,' says Theis Kragh.

Similar events have probably also affected rivers and streams.

'We have not done scientific studies of rivers and streams, but I believe this could be the explanation why there are only very few fish in otherwise healthy rivers and streams that should contain lots of fish.'

Slower drainage can help

Theis Kragh and his colleagues are now working on tracing the organic material in Lake Filsø back to its point of origin in the catchment surrounding the lake.

'If we know where it comes from - which field or heath - we can work with the drainage of the particular area. Currently, the drainage is so effective that organic matter is flushed very quickly into the lake. If the drainage gets slowed down, more rainwater will be absorbed by the soil rather than being washed out into the lake,' he says.

Denmark also experienced hot weather and drought in 2019 but received a little more rain than in 2018, and Lake Filsø was not exposed to the same phenomenon as in 2018.

Contrary to popular views, parental smartphone use is rarely associated with poor parenting, and more often than not, tends to be associated with warm and attached parenting.

A team of researchers including Dr Lynette Vernon from ECU, Dr Bep Uink and Dr. Helen Correia from Murdoch University and Dr Kathryn Modecki from Griffith University found these positive links when they partnered with the ABC to survey Australians about their relationship with their smartphone.

Published today in the Journal of Child Psychology and Psychiatry, the researchers analysed 3,659, parent-based surveys*, and tested 12* different measures of smartphone use, to assess associations between smartphone use and parenting and found little evidence of a direct link.

They then explored whether the effect of phone use on parenting depended on whether or not it displaced time with family and was associated with family conflict.

At low levels of displacing time with family, more smartphone use was associated with better, not worse parenting.

"For parents, the smartphone is an essential link to the outside world for support, knowledge or to connect with others in similar situations," Dr Lynette Vernon said.

"Parental smartphone use has been demonised as a risk to families, by various sectors of the community and media,'' says lead researcher Dr Kathryn Modecki, also a member of Menzies Health Institute Queensland.

"But across diverse family environments, smartphones play multiple roles in family life, including provision of social support and information, and allowing for work and digital errands. As long as phones are not heavily impacting on family time, smartphones tend to be tied to positive (and not negative) parenting."

The researchers used a transparent approach to map 84 ways smartphones could link to family wellbeing, using common self-report measures.

"There is a moral panic about screen time, but it would be naïve to ignore the online context where parents can be meaningfully assisted to gain information and support and where social relationships can unfold albeit via the smartphone platform," says Dr Bep Uink.

Dr Vernon suggested, "Our research finds little evidence of problems, and there is still a great deal more to understand about the role of smartphones in modern-day family life, especially as we traverse the COVID-19 landscape."

The research team is further investigating what modern life in Australia looks like during COVID-19, and their new survey is available if you would like to contribute to their research.

In the semi-arid Texas High Plains, growers and producers are concerned about the sustainability of beef and dairy industries, which rely heavily on irrigated corn for feed-grain and silage. A main source of irrigation--the Ogallala Aquifer--is declining rapidly. The aquifer's decline emphasizes the need for producers and growers to find alternative, water-efficient forage crops for sustainable beef and dairy production in the region.

In a new study published in Crop Science, researchers from Texas Tech University investigated the potential of forage sorghum and pearl millet as alternatives to corn for forage production. The 2-year study evaluated the physiological responses of multiple varieties of all three crops under various irrigation regimes, including dryland. The team collected data on leaf water potential, stomatal conductance, and canopy temperature. They also studied the influence of these responses on biomass production and nutritive values.

The study reported that sorghum showed better physiological responses and produced greater biomass under water-stress conditions compared to pearl millet and corn. Though the nutritive value of sorghum was lower than corn, sorghum could provide growers with an alternative to produce higher biomass with less water. As a management option, forage sorghum could be mixed with high nutrition supplements to achieve desirable feed quality and increase profitability.

Through deep genetic analyses, Stanford Medicine scientists and their collaborators have found conclusive scientific evidence of contact between ancient Polynesians and Native Americans from the region that is now Colombia — something that’s been hotly contested in the historic and archaeological world for decades.

“Genomics is at a stage where it can really make useful contributions to answering some of these open questions,” said Alexander Ioannidis, PhD, a postdoctoral scholar at Stanford. “I think it’s really exciting that we, as data scientists and geneticists, are able to contribute in a meaningful way to our understanding of human history.”

Before this study was conducted, proponents of Native American and Polynesian interaction reasoned that some common cultural elements, such as a similar word used for a shared agricultural staple, hinted that the two populations had mingled before Europeans settled in South America. Those who disagreed pointed to studies with contrasting conclusions and the fact that the two groups were separated by thousands of miles of open ocean.

This new study is the first to show, through conclusive genetic analyses, that the two groups indeed encountered one another, and did so before Europeans arrived in South America. To conduct the study, Ioannidis and a team of international researchers collected genetic data from more than 800 living Indigenous inhabitants of several South American countries, Mexico and Polynesia, conducting extensive genetic analyses to find signals of common ancestry. Based on trackable, heritable segments of DNA, the team was able to trace common genetic signatures of Native American and Polynesian DNA back hundreds of years.

“Our laboratory in Mexico has been very interested in understanding the genetic diversity of populations throughout Latin America and, more generally, of underrepresented populations in genomic research,” said Andrés Moreno-Estrada, PhD, professor and head of genomic services at the National Laboratory of Genomics for Biodiversity in Mexico. “Through this research, we wanted to reconstruct the ancestral roots that have shaped the diversity of these populations and answer deep, long-standing questions about the potential contact between Native Americans and Pacific Islanders, connecting two of the most understudied regions of the world.”

A paper detailing the study will be published July 8 in Nature. Ioannidis, who conducted much of this work while a graduate student at Stanford’s Institute for Computational and Mathematical Engineering, is the lead author. Moreno-Estrada is the senior author.

The mystery of the sweet potato

Before the study brought scientific evidence to the debate, the idea that Native Americans and Polynesians had crossed paths originated from a complex — both in its structure and origins -- carbohydrate: the sweet potato. It turns out the sweet potato, which was originally domesticated in South and Central America, has also been known to grow in one other place prior to European contact. That place is known as Oceania, which consists of many islands, including Polynesia.

“The sweet potato is native to the Americas, yet it’s also found on islands thousands of miles away,” Ioannidis said. “On top of that, the word for sweet potato in Polynesian languages appears to be related to the word used in Indigenous American languages in the Andes.”

The overlap in culture made some archaeologists and historians think it was not only feasible, but likely, that the potato’s arrival in Polynesia was the result of the two peoples mingling.

The researchers believe that the Polynesians landed in what is now Colombia. It is also possible, though less likely due to their coastal travel norms, that one or two ships carrying Native Americans could have sailed off course and run into Polynesia, Ioannidis said.

Without scientific evidence, the idea of overlap was just conjecture. Earlier, other groups of researchers turned to the genetics of the sweet potato, hoping to show that the domesticated potatoes from South America and Polynesia were genetically one and the same. But their efforts to trace the tubers have been inconclusive, as the sweet potato’s genetic origins were too complex to definitively point to human-mediated spread.

Other studies have analyzed ancient DNA from bones belonging to Native Americans and native Polynesians. Ancient DNA samples, however, are often degraded, so these studies were unable to provide sufficient evidence that the two populations shared a moment in history.

Carriers of history

Ioannidis’ team took a different, big data approach, analyzing the DNA of hundreds of Indigenous people from Polynesia, Mexico and South America. Before collecting any samples or conducting genetic analyses, the researchers visited the communities to explain the study, gauge interest in participation and ask for consent. The scientists then collected saliva samples from 807 participants on 17 Polynesian islands and 15 Native American groups along the Pacific coast of the Americas from Mexico to Chile, conducting genetic analyses to look for snippets of DNA that are characteristic of each population and for segments that are “identical by descent,” meaning they are inherited from the same ancestor many generations ago.

“We found identical-by-descent segments of Native American ancestry across several Polynesian islands,” Ioannidis said. “It was conclusive evidence that there was a single shared contact event.” In other words, Polynesians and Native Americans met at one point in history, and during that time people from the two cultures produced children with both Native American and Polynesian DNA. Statistical analyses confirmed the event occurred in the Middle Ages, around A.D. 1200, which is “around the time that these islands were originally being settled by native Polynesians,” Ioannidis said. Using computational methods developed as part of Ioannidis’ graduate work, the team then localized the source of the Native American DNA to modern-day Colombia.

“If you think about how history is told for this time period, it’s almost always a story of European conquest, and you never really hear about everybody else,” Ioannidis said. “I think this work helps piece together those untold stories — and the fact that it can be brought to light through genetics is very exciting to me.”

Graphene consists of a single layer of carbon atoms arranged in a honeycomb structure. The material is of interest not only in basic research but also for various applications given to its unique properties, which include excellent electrical conductivity as well as astonishing strength and rigidity. Research teams around the world are working to further expand these characteristics by substituting carbon atoms in the crystal lattice with atoms of different elements. Moreover, the electric and magnetic properties can also be modified by the formation of pores in the lattice.

Ladder-like structure

Now, a team of researchers led by the physicist Professor Ernst Meyer of the University of Basel and the chemist Dr. Shi-Xia Liu from the University of Bern have succeeded in producing the first graphene ribbons whose crystal lattice contains both periodic pores and a regular pattern of nitrogen atoms. The structure of this new material resembles a ladder, with each rung containing two atoms of nitrogen.

In order to synthesize these porous, nitrogen-containing graphene ribbons, the researchers heated the individual building blocks step by step on a silver surface in a vacuum. The ribbons are formed at temperatures up to 220°C. Atomic force microscopy allowed the researchers not only to monitor the individual steps in the synthesis, but also to confirm the perfect ladder structure - and stability - of the molecule.

Extraordinary properties

Using scanning tunneling microscopy, the scientists from the Department of Physics and the Swiss Nanoscience Institute (SNI) at the University of Basel also demonstrated that these new graphene ribbons were no longer electrical conductors, like pure graphene, but actually behaved as semiconductors. Colleagues from the Universities of Bern and Warwick confirmed these findings by performing theoretical calculations of the electronic properties. "The semiconducting properties are essential for the potential applications in electronics, as their conductivity can be adjusted specifically," says Dr. Rémy Pawlak, first author of the study.

From the literature, it is known that a high concentration of nitrogen atoms in the crystal lattice causes graphene ribbons to magnetize when subjected to a magnetic field. "We expect these porous, nitrogen-doped graphene ribbons to display extraordinary magnetic properties," says Ernst Meyer. "In the future, the ribbons could therefore be of interest for applications in quantum computing."

Duke University researchers have made the first time-lapse movies of the sheet-like latticework that surrounds and supports most animal tissues.

A thin layer of extracellular matrix known as the basement membrane lines many surfaces of the body such as the skin, blood vessels and urinary tract; and it surrounds muscles, fat, and peripheral nerves. While basement membranes play key roles in development, tissue function, and human disease, visualizing them in living organisms has been difficult to do, until now.

By genetically modifying C. elegans worms to create basement membrane proteins that glow under fluorescent light, the researchers say it's possible to see for the first time how basement membranes are assembled during development, and how they change and regenerate throughout life. The work may help to pinpoint what might be going wrong in human diseases ranging from kidney disease to invasive cancer.

"We wouldn't be here without basement membranes," said Duke biology professor David Sherwood, who led the research.

Basement membranes have been around for more than 600 million years, since the first multicellular animals evolved from their single-celled ancestors.

They're the Scotch tape that helps attach cells together to form tissues, maintaining healthy skin. They're the molecular sieves that filter blood in the kidneys, protect blood vessels and muscles from stretching and compression, and harbor growth factors that tell cells where to go, what to become, and when to divide.

But because most basement membranes lie deep within the body, beyond the reach of light microscopes, visualizing them in living tissues is hard to do in humans.

So Sherwood's team looked at them in millimeter-long transparent worms, using a gene-editing technique called CRISPR to label 29 basement membrane proteins with green glowing tags to see when and where each protein is found using time-lapse microscopy.

Getting a glimpse of these proteins in action inside a live animal offers a much more complete picture than previous experiments that looked at dissected and fixed tissues, which only provide a snapshot of proteins frozen in time, said postdoctoral fellow Eric Hastie.

"As a result, they have generally been thought of as 'boring' static structures," Hastie said

In some movies, the researchers tracked fluorescent proteins moving within the basement membrane lining the worm's throat. In others, they watched the rapid remodeling of the basement membrane surrounding the worm's gonad as it grew more than 90-fold in size.

Surprisingly, the movies show that most basement membrane proteins don't stay put after they're deposited. While some core components are static, the scientists were surprised to see that many proteins moved within this stable scaffolding.

"Our findings suggest basement membranes quickly change their properties to support mechanically active tissues and they may act as highways that allow growth factors to rapidly travel," Sherwood said.

"We've just started getting to play with this tool kit," Hastie said. But the team says their work offers a new way to study the basement membrane defects underlying tissue degeneration during aging, and diseases ranging from diabetes to muscular dystrophy.

The discovery of green fluorescent protein (GFP), which is made by a jellyfish, transformed cell biology. It allowed scientists to stitch the GFP sequence to proteins from other organisms to trace their movements and interactions in living cells. Now, researchers reporting in ACS Applied Materials & Interfaces have designed peptide nanoparticles that can each glow in a variety of colors, opening the door for many new biomedical applications.

Scientists have tried to mimic the fluorescence of GFP in small molecules such as chromophore-containing polymers or fluorescent peptide nanostructures. Peptides, which are small pieces of proteins, are attractive because of their structural simplicity and biocompatibility. However, previous fluorescent peptide nanomaterials glow in only one color, which limits their use. Yuefei Wang and colleagues wanted to make peptides that can fluoresce in a rainbow of colors.

The researchers designed 12 peptides that contained 1-3 copies of the amino acids phenylalanine, tyrosine, tryptophan or histidine, all of which are weakly fluorescent in the visible range. They added a hydrophobic ferrocene group to one end of the peptide, which caused multiple peptides to assemble into spherical fluorescent nanoparticles. The ferrocene group also changed the emission properties, or colors, of the peptides. The researchers found that each peptide nanoparticle could glow in more than one color, and together, the 12-peptide palette encompassed all colors in the visible region of light. The peptide colors were photostable and showed no toxicity when added to human cells. These results indicate that the peptide nanoprobes could be substituted for fluorescent proteins, such as GFP, in biomedical imaging, although the fluorescence quantum yield is not as high, the researchers say.

A new analysis led by researchers at Johns Hopkins Bloomberg School of Public Health found that the number of U.S. prison residents who tested positive for COVID-19 was 5.5 times higher than the general U.S. population, with a prisoner case rate of 3,251 per 100,000 residents as compared to 587 cases per 100,000 in the general population.

The researchers also found the death rate of U.S. prisoners was 39 deaths per 100,000 prison residents, higher than that of the U.S. population at 29 deaths per 100,000 people. After adjusting for age and sex differences between the two groups, the death rate would be three times higher for prisoners compared to the general U.S. population.

The findings were published online in a research letter July 8 in JAMA.

The study, which analyzed cases and deaths from March 31 to June 6, 2020, found that COVID-19 cases in prisons increased by 8.3 percent per day compared to 3.4 percent in the general population. The analysis includes COVID-19 cases among prisoners, including active confirmed cases, recoveries, and decedents, posted on publicly available data sources such as correction departments' websites, news reports, and press releases.

"While these numbers are striking, we actually think the disparities within prisons is much greater," says lead author Brendan Saloner, PhD, associate professor in the Department of Health Policy and Management at the Bloomberg School. "Some prisons are not reporting any cases, others are not even testing inmates, so the need for policies to protect incarcerated populations is more important than ever."

For the study, the Bloomberg School researchers collaborated with the UCLA Law COVID-19 Behind Bars Data Project, a new initiative based at the University of California, Los Angeles--led by senior author, Sharon Dolovich, JD, PhD, at the University of California, Los Angeles School of Law--that collects data on prisoners in state and federal prisons.

For their analysis of COVID-19 deaths, the researchers drew from information available from departments of corrections and external medical examiner reports. Using data from the Centers for Disease Control and Prevention and the U.S. Census Bureau's American Community Survey, the researchers were able to gather state-level data about COVID-19 cases, deaths, and demographics for the general U.S. population.

The researchers counted COVID-19 cases and deaths separately for prisoners and the general population. During the study period, there were 42,107 cases of COVID-19 and 510 deaths among 1,295,285 prison residents. Among the U.S. population, there were 1,920,904 infections and 95,608 deaths.

Prison populations are especially vulnerable to the spread of a highly infectious disease like COVID-19. Close confinement, limited access to personal protective equipment, and high rates of preexisting respiratory and cardiac conditions are factors that can exacerbate the spread of COVID-19 among the two-plus million people incarcerated in America's jails, prisons, and correctional facilities. Policies that have potential to curb the spread of disease include the early release of prisoners unlikely to pose a risk of reoffending, implementing strong infection control practices, and using widespread testing.

"Prisoners have a right to adequate protection of their health while incarcerated," says Saloner. "The reality of these findings shows that we aren't coming anywhere close to meeting their basic needs. Ultimately, it creates a dangerous situation for the inmates, prison staff, the communities that prisons are located in, and in our overall effort to contain the crisis."

Texas' future climate will feature drier summers and decreasing water supplies for much of the state for the remainder of the 21st century - likely resulting in the driest conditions the state has endured in the last 1,000 years, according to a team of researchers led by a Texas A&M University professor.

Using the most advanced climate models, the team projected drought conditions and relevant information for stakeholders like agricultural producers, large surface water suppliers, small groundwater water districts and regional water planning districts.

The researchers found the message is clear: Texas is getting hotter and drier, and the time to take action is now.

Regents Professor John Nielsen-Gammon, director of the Texas Center for Climate Studies and the Texas State Climatologist, said data shows Texas was much wetter 10-15,000 years ago coming out of the last Ice Age. Since then, the state's climate has mostly been similar to today's, with the exception of some wetter and drier periods. In the past thousand years, there have been multiple decades of extended drought periods called "megadroughts" - something Texas will likely see through the end of the century.

"Our study shows that the drier conditions expected in the latter half of the 21st century could be drier than any of those megadroughts, depending on how you measure dryness," Nielsen-Gammon said.

Nielsen-Gammon and colleagues from the University of Texas at Austin, Texas State University, the University of Oklahoma, NASA and others recently had their work published in the Earth's Future.

Texas policy makers have developed water projections and conservation plans for decades, but these fall short in many areas, the study concluded.

The drought of the 1950s is still considered the "drought of record" and remains the most severe in Texas in the past 125 years. But current water plans do not take into consideration likely declines in Texas' water supply due to future climate change.

"The state water plan doesn't explicitly consider climate change in figuring out how water supply and water demand will both change," Nielsen-Gammon said. "As our paper points out, pinning numbers on either of those changes is a difficult challenge, and it's not simply a matter of estimating changes in precipitation. Tying future water supply to criteria established by the drought of record is a defensible choice, but policymakers should be aware that the chances of exceeding the drought of record are probably increasing year by year."

The report notes that parts of Texas will likely be hit harder by drier conditions than the rest of the state.

West Texas is especially prone to drought or even megadrought conditions, according to the report.

"West Texas seems most likely to get a double whammy: decreased rainfall and increased temperatures," Nielsen-Gammon said. "Even though rainfall has increased statewide over the past century by about 10 percent, West Texas has seen little to no increase. West Texas is already planning for what happens as one or more critical aquifers get depleted. Climate change is going to make that depletion happen a little bit faster, but the decline of the Ogallala Aquifer is primarily caused by water extraction for irrigation rather than by climate change."

It's very likely that Texas will continue to become hotter and drier because any long-term changes in precipitation will be "dwarfed" by how much more evaporation will deplete the water supply, he said. But droughts are temporary by definition, so it wouldn't be correct to think of the future as a state of permanent drought, Nielsen-Gammon said.

"It's really a change in the climate, with the normally dry conditions in West Texas slowly migrating toward East Texas," he said.

Nielsen-Gammon said the severity of the future dryness will likely depend on local circumstances. There are key questions that remain to be answered.

"These include ones such as, does it matter what time of year sees increases or decreases in precipitation? How much water supply is there? Is the most important issue the amount of water or the health of the crops and foliage? Is it more important to get runoff or to have the rainfall soak into the ground?" he said.

Students at elementary and secondary schools that offer healthier food offerings and more opportunities for physical activities have a healthier body mass index, according to Rutgers researchers.

The study, published in Preventive Medicine Reports, uses professional measures of students' height and weight - the gold standard for studying childhood obesity - in a study on the effects of a school's food offerings and physical activity environment.

Almost one in five children and adolescents in the United States are obese. Since children eat up to two meals per day and can get 40 percent of their daily physical activity at schools, schools play a major role in obesity-related behaviors. Although recent policies and programs, such as the National School Lunch Program, have focused on promoting healthier school environments, there is little evidence of the consequences for children's weight.

The study looked at the healthfulness over the period of one school year of items offered in school lunches, vending machines and other school food offerings, as well as the number of indoor and outdoor physical activity facilities and physical activity opportunities at 90 public schools that serve 19,000 students in Newark, Trenton, Camden and New Brunswick.

Researchers found that healthier food offerings and a greater number of physical activity facilities were associated with lower body mass index, on average, for students. Schools that offered an additional unhealthy item in vending machines were associated with higher student weight and those that had an additional outdoor physical activity facility correlated with lower student weight.

"Evidence of the importance of school meals and of enforcing healthy nutritional standards is particularly timely given current federal proposals to roll back those standards," said Michael Yedidia, who co-directs the New Jersey Child Health Study at the Rutgers Center for State Health Policy. "These meals are critical to the health of low-income students, who are 80 percent of those served by federal school meals programs. They provide up to half of the students' nutritional needs at low or no cost to parents."

The findings will be particularly relevant for discussions on Child Nutrition Reauthorization, the key piece of federal legislation that supports school food programs, said Punam Ohri-Vachaspati, a study co-author at Arizona State University. "Schools play a critical role in providing environments to support healthy habits among children that can influence their short and long term-health," she said.

When NASA's Aqua satellite passed over Tropical Storm Cristina in the Eastern Pacific Ocean on July 8, it gathered water vapor data that provided information about the intensity of the storm.

NASA's Aqua satellite passed over Cristina at 4:50 a.m. EDT (0850 UTC) and the Moderate Resolution Imaging Spectroradiometer or MODIS instrument gathered water vapor content and temperature information. The MODIS image showed highest concentrations of water vapor and coldest cloud top temperatures were around the center of circulation. MODIS data also showed coldest cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in those storms. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and the stronger the storms.

The National Hurricane Center noted that satellite images show that the convective organization of Cristina is gradually improving, while bands of thunderstorms are developing across the northern portion of the circulation. The center of Cristina's circulation was still under the northeastern side of the main area of convection due to moderate vertical wind shear, but that wind shear appears to be diminishing.

On July 8 at 11 a.m. EDT (1500 UTC), the center of Tropical Storm Cristina was located near latitude 14.6 degrees north and longitude 106.9 degrees west. That is about 350 miles (560 km) south-southwest of Manzanillo, Mexico.

Cristina is moving toward the northwest near 12 mph (19 kph). A turn to the west-northwest is expected by tonight, and that motion is expected to continue for the next few days. On the forecast track, the cyclone will remain well offshore the coast of Mexico. The estimated minimum central pressure is 998 millibars.

Maximum sustained winds are near 60 mph (95 kph) with higher gusts. Gradual strengthening is expected over the next couple of days, and Cristina is forecast to become a hurricane on Thursday.

National Hurricane Center forecaster Andrew Latto noted, "The decreasing shear over Cristina combined with warm sea surface temperatures and a moist air mass should allow the cyclone to intensify over the next couple of days."

NASA's Aqua satellite is one in a fleet of NASA satellites that provide data for hurricane research.

Tropical cyclones/hurricanes are the most powerful weather events on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

COLUMBUS, Ohio - Scientists have discovered that one of the good bacteria found in the human gut has a benefit that has remained unrecognized until now: the potential to reduce the risk for heart disease.

The bacteria's activity in the intestines reduces production of a chemical that has been linked to the development of clogged arteries. After it's manufactured in the gut, the chemical enters the bloodstream and travels to the liver, where it is converted into its most harmful form.

The Ohio State University researchers have traced the bacteria's behavior to a family of proteins that they suspect could explain other ways that good gut organisms can contribute to human health. In essence, these microbes compete with bad bacteria for access to the same nutrients in the gut - and if the good bacteria win, they may prevent health problems that can result from how the body metabolizes food.

Much more work is ahead, but the scientists see potential for this microbe, Eubacterium limosum, to be used for therapeutic purposes in the future. Previous research has already shown the bacterium is "good" because it calms inflammation in the gut.

"Over the last decade, it has become apparent that bacteria in the human gut influence our health in many ways. The organism we studied affects health by preventing a problematic compound from becoming a worse one," said Joseph Krzycki, professor of microbiology at Ohio State and senior author of the study. "It's too soon to say whether this bacterium could have therapeutic value. But that's what we're working toward."

The research appears online and will be published in a future edition of the Journal of Biological Chemistry.

The chemical linked to the clogged arteries that characterize atherosclerosis is called trimethylamine, or TMA. It is produced during metabolism when some intestinal microbes - generally the bacteria considered unhelpful to humans - interact with certain nutrients from food. Among those nutrients is L-carnitine, a chemical compound found in meat and fish that is also used as a nutritional supplement to improve recovery after exercise.

Krzycki and his colleagues discovered that E. limosum interacts with L-carnitine in a different way in the gut, and that interaction eliminates L-carnitine's role in production of TMA (other nutrients also participate in TMA production in the gut).

The researchers attribute the bacteria's beneficial behavior to a protein called MtcB, an enzyme that cuts specific molecules off of compounds to help bacteria generate energy and survive. The process is called demethylation, and involves the removal of one methyl group - a carbon atom surrounded by three hydrogen atoms - to change a compound's structure or function.

"The bacterium does this for its own benefit, but it has the downstream effect of reducing the toxicity of TMA," Krzycki said. "Up until now, the only known gut microbial reactions with L-carnitine involved converting it into its bad form. We've discovered that a bacterium known to be beneficial could remove a methyl group and send the resulting product down another pathway without making any other harmful compounds in the process."

In these interactions, L-carnitine functions as a growth substrate - a compound consumed so the organism can live and grow, and also a target for enzyme activity. In the study, the researchers fed E. limosum cultures an assortment of potential substrates, including L-carnitine. Only when offered L-carnitine did the microbe synthesize the MtcB protein specifically to lop off L-carnitine's methyl group - in essence, MtcB is part of the bacteria's natural way to consume the nutrient.

Krzycki said finding this one significant health benefit in one species of gut bacteria suggests there is still a lot to learn about how gut bacteria can influence health outcomes associated with human metabolism.

"MtcB is part of a family of proteins with thousands of representatives that may use different compounds and change what nutrients bacteria consume in the gut," he said. "These proteins may behave very similarly chemically, but using different compounds obviously can create big changes as far as biology goes."

Researchers at Karolinska Institutet have developed a new method that can make it easier for public authorities to assess the health risks of hormone-disrupting chemicals in the environment. The method was used to evaluate the risk associated with exposure data from the population of Ronneby in Sweden where the drinking water had been contaminated with PFAS from fire-fighting foam. The study, which was published in Environmental Health Perspectives, shows that women are particularly at risk of decreased levels of thyroid hormone T3 (triiodothyronine) related to PFAS-contaminated drinking water.

PFAS (per- and polyfluoroalkyl substances) can be found in everything from ski wax to frying pans and fire-fighting foam. They are highly persistent and damaging to both human health and the environment. Amongst other effects, PFAS can cause weakened immune systems, lower birth weights and alter thyroid levels. At several places around the country, especially near fire-drill sites, high concentrations of PFAS have been found in the drinking water. There is therefore a pressing need to explore the health risks to which the local populations are exposed.

"It's not enough to know that the levels exceed a limit value," says lead author Antero Silva, doctoral student at the Institute of Environmental Medicine at Karolinska Institutet in Sweden. "We wanted to develop a method that describes how great the risk is while dealing with the uncertainty of the data."

The problem with PFAS have been highlighted recently in the reality-based Hollywood film Dark Waters, which follows lawyer Robert Bilott (played by Mark Ruffalo) as he exposes how US industry has been covering up the risks of PFAS for decades. Legal proceedings are also underway in Sweden following a lawsuit against the municipal water company filed by the residents of one of the worst affected towns, Ronneby.

In this present study, the researchers have linked information on how PFAS influence the thyroid hormone T3, taking into account differences in sensitivity between individuals. Using exposure data from Ronneby, the researchers calculated how many people might be affected and estimated that around four per cent of the local women had blood PFAS levels high enough to cause a 10% drop in T3 levels.

“Using a large number of computer simulations we can describe the risk in terms of probability,” explains Antero Silva. “Our results show that it is mainly women who risk being affected and that those who have lived a long time in Ronneby are more likely to have reduced levels of the thyroid hormone T3.”

The thyroid hormone controls body metabolism, and an underactive thyroid (hypothyroidism) can lead to tiredness, concentration problems and depression. The hormone is also crucial to fetal development. In 2019, 472,000 people in Sweden were given drugs for low levels of thyroid hormone, 82 per cent of whom were women. The new study does not focus on the risk of disease, however, but on the likelihood of hormone levels being affected in a certain population group. It is therefore only possible to give the risk at population level, rather than identify which individuals are affected.

“There are many factors that determine whether or not you may get sick,” says Silva. “However, the body has an ability to compensate for environmental influence, but PFAS are a factor that can increases the risk of adverse effects. So, it is important for the health of those exposed to PFAS to be checked.”

The risks of chemicals in the environment are mainly assessed by comparing exposure with different limit values, which can give a false impression that there is a line that separates safe from dangerous. The researchers hope that the new method will be able to help public authorities analyse risks more carefully while paying closer attention to uncertainty and variation in the data.

Water is vital to the survival of life. However, water scarcity has become a major problem in modern society. Today, one-fifth of the world's population lives in water- deficient areas, especially in areas where there is no electricity. For people in such areas, access to clean drinking water is often a difficult task. Therefore, they urgently need an efficient, low-cost, sustainable, and easily accessible technologies and devices to generate clean water. Solar energy is one of the most abundant and widespread resources on earth. Solar-powered water purification technology is simple and efficient to obtain clean drinking water from non-drinkable water sources such as lake water, sewage or seawater.

Nowadays, a team led by Prof. Shu-Hong Yu from the University of Science and Technology of China (USTC) report an efficient and sustainable biomimetic hierarchical solar steam generator (HSSG) based on bacterial cellulose (BC) nanocomposites. This HSSG is fabricated through a one-step aerosol-assisted biosynthesis process. The designed microbial synthesis process is successfully combined with the deposition of nanomaterials, and a sophisticated biomimetic hierarchical structure is constructed simply and efficiently. The hierarchical structure of this HSSG contains three continuous layers with different functions, including light absorbing layer of carbon nanotubes/BC, thermal insulation layer of glass bubbles /BC and wood substrate for supporting and water transporting. In HSSG, three-dimensional (3D) cellulose nanofiber network of BC hydrogel significantly reduced the energy consumption to convert the liquid water into vapor and accelerate the vaporization of water. Owing to the hierarchical structure design and reduced vaporization enthalpy of nanocomposites of HSSG, a high evaporation rate of 2.9 kg m-2 h-1 and solar-to-vapor efficiency of 80 % can be achieved.

In this HSSG, the hierarchical structure nanocomposites grow on the wood substrate and are tightly combined with the wood substrate through BC network of nanofibers. BC nanofibers crosslink with the cellulose of wood forming infiltrating layer in wood, which acts as a strong binder between wood and BC nanocomposite layers. This structure ensures the fast water transportation from wood to the BC nanocomposite layers and makes them firmly attached to wood substrate, which provides the structural foundation of thermal insulation and water transportation. Glass bubbles are microscale hollow glass spheres, which provides the structural foundation of thermal insulation and water transportation. On the top of the device, the carbon nanotubes and BC nanocomposite layer have sophisticated interlaced structure where carbon nanotubes and cellulose nanofibers form double-network of nanofibers. In this double-network, carbon nanotubes function as highly effective solar light absorber and BC nanofibers are used to transport water and reduce the energy consumption of evaporation. This multilayered structure of wood, glass bubbles /BC and carbon nanotubes/BC is designed to achieve fast water transportation, thermal management, effective light absorption and reduced vaporization energy consumption. Moreover, to systematically investigate the relation between evaporation rate, energy efficiency and energy consumption of evaporation, the team provides a novel two-dimension chart with guide lines showing different enthalpy of vaporization. This theoretical analysis method shows potential for analyzing the contributions of different functional parts in solar steam generator devices for evaporation rate.

Comparing with other technology of solar powered water purification, HSSG have great advantage on evaporation rate, energy efficiency, sustainability and cost, which make it a promising technology for future water purification.

In a recent study, breast feeding during infancy was associated with a lower risk of lower limb fractures when children reached young adulthood, while maternal smoking was associated with a higher risk of upper limb fractures. The findings are published in the Journal of Bone and Mineral Research.

For the study, 201 participants were followed from infancy to 25 years old. While the effects of breast feeding and smoking on bone health in young adulthood were significant, there were no observed effects of birthweight.

The findings suggest that exposures during fetal development and early life may have effects on bone health in adulthood.

"This study reinforces the view that healthy bones start in utero and early childhood, suggesting that prevention of osteoporosis should start as early as possible," said senior author Graeme Jones, PhD, MD, of the University of Tasmania, in Australia.