Wednesday, August 21, 2019

Researchers Make a Heat Shield Just 10 Atoms Thick to Protect Electronic Devices

Atomically thin materials developed by Stanford researchers could create heat shields for cell phones or laptops that would protect people and temperature-sensitive components and make future electronic gadgets even more compact.

Excess heat given off by smartphones, laptops and other electronic devices can be annoying, but beyond that it contributes to malfunctions and, in extreme cases, can even cause lithium batteries to explode.

This greatly magnified image shows four layers of atomically thin materials that form a heat-shield just two to three nanometers thick, or roughly 50,000 times thinner than a sheet of paper. 

Credit: National Institute of Standards and Technology

To guard against such ills, engineers often insert glass, plastic or even layers of air as insulation to prevent heat-generating components like microprocessors from causing damage or discomforting users.

Now, Stanford researchers have shown that a few layers of atomically thin materials, stacked like sheets of paper atop hot spots, can provide the same insulation as a sheet of glass 100 times thicker. In the near term, thinner heat shields will enable engineers to make electronic devices even more compact than those we have today, said Eric Pop, professor of electrical engineering and senior author of a paper published Aug. 16 in Science Advances.

“We’re looking at the heat in electronic devices in an entirely new way,” Pop said.
Detecting sound as heat

The heat we feel from smartphones or laptops is actually an inaudible form of high-frequency sound. If that seems crazy, consider the underlying physics. Electricity flows through wires as a stream of electrons. As these electrons move, they collide with the atoms of the materials through which they pass. With each such collision an electron causes an atom to vibrate, and the more current flows, the more collisions occur, until electrons are beating on atoms like so many hammers on so many bells – except that this cacophony of vibrations moves through the solid material at frequencies far above the threshold of hearing, generating energy that we feel as heat.

Thinking about heat as a form of sound inspired the Stanford researchers to borrow some principles from the physical world. From his days as a radio DJ at Stanford’s KZSU 90.1 FM, Pop knew that music recording studios are quiet thanks to thick glass windows that block the exterior sound. A similar principle applies to the heat shields in today’s electronics. If better insulation were their only concern, the researchers could simply borrow the music studio principle and thicken their heat barriers. But that would frustrate efforts to make electronics thinner. Their solution was to borrow a trick from homeowners, who install multi-paned windows – usually, layers of air between sheets of glass with varying thickness – to make interiors warmer and quieter.

“We adapted that idea by creating an insulator that used several layers of atomically thin materials instead of a thick mass of glass,” said postdoctoral scholar Sam Vaziri, the lead author on the paper.

Atomically thin materials are a relatively recent discovery. It was only 15 years ago that scientists were able to isolate some materials into such thin layers. The first example discovered was graphene, which is a single layer of carbon atoms and, ever since it was found, scientists have been looking for, and experimenting with, other sheet-like materials. The Stanford team used a layer of graphene and three other sheet-like materials – each three atoms thick – to create a four-layered insulator just 10 atoms deep. Despite its thinness, the insulator is effective because the atomic heat vibrations are dampened and lose much of their energy as they pass through each layer.

To make nanoscale heat shields practical, the researchers will have to find some mass production technique to spray or otherwise deposit atom-thin layers of materials onto electronic components during manufacturing. But behind the immediate goal of developing thinner insulators looms a larger ambition: Scientists hope to one day control the vibrational energy inside materials the way they now control electricity and light. As they come to understand the heat in solid objects as a form of sound, a new field of phononics is emerging, a name taken from the Greek root word behind telephone, phonograph and phonetics.

“As engineers, we know quite a lot about how to control electricity, and we’re getting better with light, but we’re just starting to understand how to manipulate the high-frequency sound that manifests itself as heat at the atomic scale,” Pop said.

Eric Pop is an affiliate of the Precourt Institute for Energy. Stanford authors include former postdoctoral scholars Eilam Yalon and Miguel Muñoz Rojo, and graduate students Connor McClellan, Connor Bailey, Kirby Smithe, Alexander Gabourie, Victoria Chen, Sanchit Deshmukh and Saurabh Suryavanshi. Other authors are from Theiss Research and the National Institute of Standards and Technology.

This research was supported by the Stanford Nanofabrication Facility, the Stanford Nano Shared Facilities, the National Science Foundation, the Semiconductor Research Corporation, the Defense Advanced Research Projects Agency, the Air Force Office of Scientific Research, the Stanford SystemX Alliance, the Knut and Alice Wallenberg Foundation, the Stanford Graduate Fellowship program and the National Institute of Standards and Technology.

Contacts and sources:
Tom Abate
Stanford University

Smart Faucets Could Aid in Water Conservation

An experiment with a water-saving “smart” faucet shows potential for reducing water use. The catch? Unbeknownst to study participants, the faucet’s smarts came from its human controller.

Credit: Stanford

Barely hidden from his study participants, William Jou, a former graduate student in mechanical engineering at Stanford University, pulled off a ruse straight out of The Wizard of Oz. Except, instead of impersonating a great and powerful wizard, Jou pretended to be an autonomous sink. He did this to test whether a sink that adapts to personal washing styles could reduce water use.

A Stanford experiment with a fake autonomous sink showed that a real smart sink could help conserve water.

Image credit: Kurt Hickman

A faucet with anything close to the brains of a mechanical engineering student doesn’t yet exist. So, Jou and his colleagues in the lab of Erin MacDonald, assistant professor of mechanical engineering, made the next best thing: a faucet that seemed to automatically adjust to a user’s preferences, but was actually controlled by Jou.

The results of their sly experiment, detailed in a paper presented Aug. 20 at the ASME 2019 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE), support the idea that thoughtfully designed smart sinks could help conserve water by regulating water use and nudging users to develop more water-conscious habits.

“We looked at the faucet because that’s where a lot of water usage in the home occurs, but when you compare your sink to other products in the house – a thermostat or refrigerator – you see that there haven’t been updates to how the sink works in a very long time,” said MacDonald, who is senior author of the paper. “There have been small updates but nothing that really harnesses the power of technology.”

Participants in this experiment had to wash dishes three times, with Jou secretly controlling the temperature and flow of the sink during the second washing only. With Jou involved, participants used about 26 percent less water compared to their first washing. In the third round, they still used 10 percent less water compared to the first round, even though the sink was back to being brainless. This shift in water use happened without participants knowing the experiment was about water conservation.

“Water conservation is particularly relevant given our location in California,” said Samantha Beaulieu, a graduate student and co-author of the paper. “We also wanted to see if people’s habits were adjustable; if interacting with this faucet could then change how people interact with a manual faucet. The results we found seem to indicate that’s possible.”
Pay no attention to the grad student

In order to create a situation where people would trust – and hopefully enjoy – a sink that makes water decisions for them, Jou closely monitored the participants’ washing styles during their first round of cleaning so he could emulate them in the second round.

“As the algorithm, I’m trying to use that information to leverage their cognitive style or user behavior style to see if I can help them use less water while still keeping them happy,” described Jou, who is lead author of the paper. “Whereas a lot of products today are made for general use, this is a product that’s learning about you and adapting to what your style is.”

In surveys after the experiment, 96 percent of participants who interacted with the smart sink (there was a control group that washed dishes three times without Jou) said they thought there was potential for smart faucets to save water. Many of them even expressed interest in buying such a product.

“Most people were pretty amazed by the sink,” said Beaulieu. “A lot of people left the experiment asking what the algorithm was or asking how it worked or how to see more. We basically told them we’d have to wait until the end of the experiment to answer those questions.”

While the results from and reaction to washing with Jou’s assistance were impressive, the researchers were particularly heartened by how such a brief interaction with the “autonomous” function changed participants’ water use.

“We didn’t even plan on having that third step until very late in the research, when we were pilot testing,” said MacDonald. “I never would have thought that having just one experience with ‘William the Algorithm’ people would retain the training and wash their dishes differently.”
The sink of the future

The researchers imagine a future where hospital sinks encourage employees to wash their hands properly and our personal sink and shower preferences can be transferred to hotels and friends’ houses. Schools and neighborhoods could organize competitions to save water and raise water conservation awareness. Through additional features, the sink could even detect leaks.

That being said, creating this one sink required years of work and didn’t even include an algorithm. In addition to implanting artificial intelligence, making a version for mass production that’s actually autonomous would require sensors that could differentiate between users and between scenarios – such as washing a pot versus a fork versus hands. Still, the researchers are optimistic that studies like these could lay the groundwork to support those developments.

“We’re all human beings – we have good days and bad days. A product like this could have a large impact because it’s growing and learning with you as you change,” said Jou. “This faucet is working toward saving water but it’s also keeping its user happy. In the long term, products like this might be our future.”

Adrienne Lim, an undergraduate at Stanford, is also co-author of the paper. This research was funded by the National Science Foundation.

Contacts and sources:
Taylor Kubota
Stanford University

Significant Changes Expected in the Ocean Due to Climate Change, New Study Offers Road Map

Researchers led by Princeton University examined a range of possible climate-related impacts on the ocean to predict when these impacts are likely to occur. Some impacts – such as sea temperature rise and acidification — have already begun while others — like changes to microbial productivity, which serves as the basis of the marine food web, will happen over the next century. Images from NASA EarthData show ocean color, an indicator of microbial productivity.
Earth horizon
Image courtesy of NASA EarthData

Sea temperature and ocean acidification have climbed during the last three decades to levels beyond what is expected due to natural variation alone, a new study led by Princeton researchers finds. Meanwhile other impacts from climate change, such as changes in the activity of ocean microbes that regulate the Earth’s carbon and oxygen cycles, will take several more decades to a century to appear. The report was published Aug. 19 online in the journal Nature Climate Change.

The study looked at physical and chemical changes to the ocean that are associated with rising atmospheric carbon dioxide due to human activities. “We sought to address a key scientific question: When, why and how will important changes become detectable above the normal variations that we expect to see in the global ocean?” said Sarah Schlunegger, a postdoctoral research associate at Princeton University’s Program in Atmospheric and Oceanic Sciences (AOS).

The study confirms that outcomes tied directly to the escalation of atmospheric carbon dioxide have already emerged in the existing 30-year observational record. These include sea surface warming, acidification and increases in the rate at which the ocean removes carbon dioxide from the atmosphere.

In contrast, processes tied indirectly to the ramp up of atmospheric carbon dioxide through the gradual modification of climate and ocean circulation will take longer, from three decades to more than a century. These include changes in upper-ocean mixing, nutrient supply, and the cycling of carbon through marine plants and animals.

“What is new about this study is that it gives a specific timeframe for when ocean changes will occur,” said Jorge Sarmiento, the George J. Magee Professor of Geoscience and Geological Engineering, Emeritus. “Some changes will take a long time while others are already detectable.”

The ocean provides a climate service to the planet by absorbing excess heat and carbon from the atmosphere, thereby slowing the pace of rising global temperatures, Schlunegger said. This service, however, comes with a penalty — namely ocean acidification and ocean warming, which alter how carbon cycles through the ocean and impacts marine ecosystems.

Acidification and ocean warming can harm the microbial marine organisms that serve as the base of the marine food web that feeds fisheries and coral reefs, produces oxygen and contributes to the draw-down of atmospheric carbon dioxide concentration.

The study aimed to sift out ocean changes linked to human-made climate change from those due to natural variability. Natural fluctuations in the climate can disguise changes in the ocean, so researchers looked at when the changes would be so dramatic that they would stand out above the natural variability.

Climate research is often divided into two categories, modeling and observations — those scientists who analyze observations of the real Earth, and those who use models to predict what changes are to come. This study leverages the predictions made by climate models to inform observational efforts of what changes are likely, and where and when to look for them, Schlunegger said.

The researchers conducted modeling that simulates potential future climate states that could result from a combination of human-made climate change and random chance. These experiments were performed with the Earth System Model, a climate model that has an interactive carbon cycle, so that changes in the climate and carbon cycle can be considered in tandem.

Use of the Earth System Model was facilitated by John Dunne, who leads ocean carbon modeling activities at the National Oceanic and Atmospheric Administration (NOAA)’s Geophysical Fluid Dynamics Laboratory in Princeton. Along with Sarah Schlunegger and Jorge Sarmiento, the Princeton team included Richard Slater, senior earth system modeler in AOS, and Keith Rodgers, an AOS research oceanographer now at Pusan National University in South Korea. The team also included Thomas Frölicher, a professor at the University of Bern and a former postdoctoral fellow at Princeton, and Masao Ishii of the Japan Meteorological Agency.

The finding of a 30- to 100-year delay in the emergence of effects suggests that ocean observation programs should be maintained for many decades into the future to effectively monitor the changes occurring in the ocean. The study also indicates that the detectability of some changes in the ocean would benefit from improvements to the current observational sampling strategy. These include looking deeper into the ocean for changes in phytoplankton, and capturing changes in both summer and winter, rather than just the annual mean, for the ocean-atmosphere exchange of carbon dioxide.

“Our results indicate that many types of observational efforts are critical for our understanding of our changing planet and our ability to detect change,” Schlunegger said. These include time-series or permanent locations of continuous measurement, as well as regional sampling programs and global remote sensing platforms.

The project was funded by a NASA Earth Science Division grant (NNX17AI75G) and NOAA grants (NA17RJ2612, NA08OAR4320752 and NA11OAR4310066). Additional support came from the Institute for Basic Science in Busan, South Korea, and the Swiss National Science Foundation.

The study, “Emergence of anthropogenic signals in the ocean carbon cycle,” was published in Nature Climate Change on Aug. 19, 2019. DOI: 10.1038/s41558-019-0553-2

Contacts and sources:
Catherine Zandonella
Princeton University

Citation: “Emergence of anthropogenic signals in the ocean carbon cycle,”
Sarah Schlunegger, Keith B. Rodgers, Jorge L. Sarmiento, Thomas L. Frölicher, John P. Dunne, Masao Ishii, Richard Slater. Emergence of anthropogenic signals in the ocean carbon Nature Climate Change, 2019; DOI: 10.1038/s41558-019-0553-2

Fake News Can Lead to False Memories

Voters may form false memories after seeing fabricated news stories, especially if those stories align with their political beliefs, according to research in Psychological Science.

The research was conducted in the week preceding the 2018 referendum on legalizing abortion in Ireland, but the researchers suggest that fake news is likely to have similar effects in other political contexts, including the US presidential race in 2020. 

Credit:   Association for Psychological Science

“In highly emotional, partisan political contests, such as the 2020 US Presidential election, voters may ‘remember’ entirely fabricated news stories,” says lead author Gillian Murphy of University College Cork. “In particular, they are likely to ‘remember’ scandals that reflect poorly on the opposing candidate.”

The study is novel because it examines misinformation and false memories in relation to a real-world referendum, Murphy explains. She and her colleagues, including APS Past President Elizabeth Loftus of the University of California, Irvine, recruited 3,140 eligible voters online and asked them whether and how they planned to vote in the referendum. Next, the experimenters presented each participant with six news reports, two of which were made-up stories that depicted campaigners on either side of the issue engaging in illegal or inflammatory behavior. After reading each story, participants were asked if they had heard about the event depicted in the story previously; if so, they reported whether they had specific memories about it.

The researchers then informed the eligible voters that some of the stories they read had been fabricated, and invited the participants to identify any of the reports they believed to be fake. Finally, the participants completed a cognitive test.

Nearly half of the respondents reported a memory for at least one of the made-up events; many of them recalled rich details about a fabricated news story. The individuals in favor of legalizing abortion were more likely to remember a falsehood about the referendum opponents; those against legalization were more likely to remember a falsehood about the proponents. Many participants failed to reconsider their memory even after learning that some of the information could be fictitious. And several participants recounted details that the false news reports did not include.

“This demonstrates the ease with which we can plant these entirely fabricated memories, despite this voter suspicion and even despite an explicit warning that they may have been shown fake news,” Murphy says.

Participants who scored lower on the cognitive test were no more prone to forming false memories than were higher scorers, but low scorers were more likely to remember false stories that aligned with their opinions. This finding suggests that people with higher cognitive ability may be more likely to question their personal biases and their news sources, the researchers say.

Other collaborators on the project include Rebecca Hofstein Grady and Linda J. Levine at UC Irvine and Ciara Greene of University College Dublin. The researchers say they plan to expand on this study by investigating the influence of false memories related to the Brexit referendum and the “#MeToo movement.”

Loftus says understanding the psychological effects of fake news is critical given that sophisticated technology is making it easier to create not only phony news reports and images, but fake video, as well.

“People will act on their fake memories, and it is often hard to convince them that fake news is fake,” Loftus says. “With the growing ability to make news incredibly convincing, how are we going to help people avoid being misled? It’s a problem that psychological scientists may be uniquely qualified to work on.”

Contacts and sources:
Association for Psychological Science

Tuesday, August 20, 2019

Shape-Shifting Sheets

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a mathematical framework that can turn any sheet of material into any prescribed shape, inspired by the paper craft kirigami (from the Japanese, kiri, meaning to cut and kami, meaning paper).

Researchers have developed a mathematical framework that can turn any sheet of material into any prescribed shape, inspired by the paper craft called kirigami. 
Kirigami cuts on paper
Image courtesy of Harvard SEAS

Unlike its better-known cousin origami, which uses folds to shape paper, kirigami relies on a pattern of cuts in a flat paper sheet to change its flexibility and allow it to morph into 3D shapes. Artists have long used this artform to create everything from pop-up cards to castles and dragons.

“We asked if it is possible to uncover the basic mathematical principles underlying kirigami and use them to create algorithms that would allow us to design the number, size and orientation of the cuts in a flat sheet so that it can morph into any given shape,” said L. Mahadevan, de Valpine Professor of Applied Mathematics, Physics, and Organismic and Evolutionary Biology, the senior author on the paper.

Image courtesy of Harvard SEAS

“Specifically, if we are given a general shape in two-or-three dimensions, how should we design the cut patterns in a reference shape so that we can get it to deploy to the final shape in one motion?” said Gary P. T. Choi, a graduate student at SEAS and first author of the paper. “In this work, we solve that problem by identifying the constraints that have to be satisfied in order to achieve this cut pattern, use a numerical optimization approach to determine the patterns, and then verify this experimentally.”

The research is published in Nature Materials.

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a mathematical framework that can turn any sheet of material into any prescribed shape, using the paper craft kirigami.Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a mathematical framework that can turn any sheet of material into any prescribed shape, using the paper craft kirigami.

Image courtesy of Harvard SEAS

This research follows previous work by the Mahadevan lab that characterized how origami-based patterns could be used as building blocks to create almost any three-dimensional curved shape.

“We were actually able to do a little more with kirigami than we were able to do with origami,” said Levi Dudte, graduate student in the Mahadevan lab and co-author of the paper. “The presence of cuts and holes in the interior of the material gives kirigami the ability to change its shape significantly.”

“Our work draws on inspiration from art, tempered by the rigor of mathematics, and the challenges of engineering shape. Finding kirigami tessellations that can convert a square to a circle, or a flat sheet into a poncho is just the start. We think that this is just the beginning of a class of new ways to engineer shape in the digital age using geometry, topology, and computation,” said Mahadevan.

Next the researchers aim to explore how to combine cuts and folds to achieve any shape with a given set of properties, thus linking origami and kirigami.

This research was supported by the Croucher Foundation and the National Science Foundation.

Contacts and sources:
Leah Burrows
Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS)

New Rechargeable CCNY Aqueous Battery Challenges Lithium-Ion Dominance

A new rechargeable high voltage manganese dioxide zinc battery, exceeding the 2 V barrier in aqueous zinc chemistry, is the latest invention by City College of New York researchers. With a voltage of 2.45-2.8V, the alkaline MnO2|Zn battery, developed by Dr. Gautam G. Yadav and his group in the CCNY-based CUNY Energy Institute, could break the long dominance of flammable and expensive lithium (Li)-ion batteries in the market.

To break the previously daunting 2 V barrier in aqueous zinc chemistry, primary inventor Yadav and his team interfacially engineered two different aqueous electrolytes that deliver the theoretical capacity (308mAh/g) reversibly for many cycles.

The newly designed high voltage aqueous Zn anode batteries can challenge Li-ion's current dominance.
Credit: G.G. Yadav et al, ACS Energy Lett., 2019, 4, 2144-2146.

“The voltage of current commercially available alkaline MnO2|Zn batteries is around 1.2-1.3V, and this has been considered low compared to Li-ion which has a voltage >3V,” said Yadav.

Voltage has been Li-ion’s greatest asset and has helped fuel its rise in an energy hungry world.

“Unfortunately it contains elements that are toxic and geopolitically sensitive with Asian countries having a monopoly on mining and manufacturing them,” added Yadav.

“This has put the United States at a tremendous disadvantage and has lost its lead in energy storage industry, when in the past it was a world leader. With Mn and Zn being widely available elements, and with the U.S. being rich with them as well, it allows the U.S. to compete again. The manufacturing cost of these batteries will also be low, so it can kick start the growth of the energy storage industry in the U.S.”

Yadav’s collaborators from CCNY’s Grove School of Engineering included: Xia Wei, Jinchao Huang, Damon E. Turney and Sanjoy Banerjee, who is Distinguished Professor of Chemical Engineering and director of the CUNY Energy Institute.

Their research appears in the journal “ACS Energy Letters,” which publishes breakthrough energy-related research.

Contacts and sources:
Jay Mwamba
The City College of New York

Breaking the 2 V Barrier in Aqueous Zinc Chemistry: Creating 2.45 and 2.8 V MnO2–Zn Aqueous Batteries
Gautam G. Yadav,* Damon Turney, Jinchao Huang, Xia Wei, Sanjoy Banerjee
,ACS Energy Lett.20194XXX2144-2146
Publication Date:August 8, 2019

Ancient Roopkund Skeletons Show Mediterranean Migrants in Indian Himalayas

The lake was thought to be the site of an ancient catastrophic event that left several hundred people dead, but the first ancient whole genome data from India shows that diverse groups of people died at the lake in multiple events approximately 1000 years apart.

Context of Roopkund Lake. a) Map showing the location of Roopkund Lake. The approximate route of the Nanda Devi Raj Jat pilgrimage relative to Roopkund Lake is shown in the inset. b) Image of disarticulated skeletal elements scattered around the Roopkund Lake site. Photo by Himadri Sinha Roy.  c) Image of Roopkund Lake and surrounding mountains. 
Context of Roopkund Lake. a) Map showing the location of Roopkund Lake. The approximate route of the Nanda Devi Raj Jat pilgrimage relative toRoopkund Lake is shown in the inset. b) Image of disarticulated skeletal elements scattered around the Roopkund Lake site. Photo by Himadri Sinha Roy.c) Image of Roopkund Lake and surrounding mountains. Photo by Atish Waghwase
Credits: Photo by Atish Waghwase
© Harney et al.; Nature Communications

A large-scale study conducted by an international team of scientists has revealed that the mysterious skeletons of Roopkund Lake – once thought to have died during a single catastrophic event – belong to genetically highly distinct groups that died in multiple periods in at least two episodes separated by one thousand years. The study, published this week in Nature Communications, involved an international team of 28 researchers from institutions in India, the United States and Europe.

Situated at over 5000 meters above sea-level in the Himalayan Mountains of India, Roopkund Lake has long puzzled researchers due to the presence of skeletal remains from several hundred ancient humans, scattered in and around the lake’s shores, earning it the nickname Skeleton Lake or Mystery Lake. "Roopkund Lake has long been subject to speculation about who these individuals were, what brought them to Roopkund Lake, and how they died," says senior author Niraj Rai, of the Birbal Sahni Institute of Palaeosciences in Lucknow, India, who began working on the Roopkund skeletons when he was a post-doctoral scientist at the CSIR Centre for Cellular and Molecular Biology (CCMB) in Hyderabad, India.

The current publication, the final product of a more than decade-long study that presents the first whole genome ancient DNA data from India, reveals that the site has an even more complex history than imagined.

First ancient DNA data from India shows diverse groups at Roopkund Lake

Ayushi Nayak preparing samples for analysis in the Stable Isotope Laboratory at the Max Planck Institute for the Science of Human History. The Photo is a screen grab from the video "Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis" which can be found at:
Credit: © Ventresca Miller, A., Fernandes, R., Janzen, A., Nayak, A., Swift, J., Zech, J., Boivin, N., Roberts, P. Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis. J. Vis. Exp. (138), e58002, doi:10.3791/58002 (2018).

Ancient DNA obtained from the skeletons of Roopkund Lake – representing the first ancient DNA ever reported from India – reveals that they derive from at least three distinct genetic groups. "We first became aware of the presence of multiple distinct groups at Roopkund after sequencing the mitochondrial DNA of 72 skeletons. While many of the individuals possessed mitochondrial haplogroups typical of present-day Indian populations, we also identified a large number of individuals with haplogroups that would be more typical of populations from West Eurasia," says co-senior author Kumarasamy Thangaraj of CCMB, who started the project more than a decade ago, in an ancient DNA clean lab that he and then-director of CCMB Lalji Singh (deceased) built to study Roopkund.

Whole genome sequencing of 38 individuals revealed that there were at least three distinct groups among the Roopkund skeletons. The first group is composed of 23 individuals with ancestries that are related to people from present-day India, who do not appear to belong to a single population, but instead derived from many different groups. Surprisingly, the second largest group is made up of 14 individuals with ancestry that is most closely related to people who live in the eastern Mediterranean, especially present-day Crete and Greece. A third individual has ancestry that is more typical of that found in Southeast Asia. "We were extremely surprised by the genetics of the Roopkund skeletons. The presence of individuals with ancestries typically associated with the eastern Mediterranean suggests that Roopkund Lake was not just a site of local interest, but instead drew visitors from across the globe," says first-author Éadaoin Harney of Harvard University.

Dietary analysis of the Roopkund individuals confirms diverse origins

Stable isotope dietary reconstruction of the skeletons also supports the presence of multiple distinct groups. "Individuals belonging to the Indian-related group had highly variable diets, showing reliance on C­3 and C4 derived food sources. These findings are consistent with the genetic evidence that they belonged to a variety of socioeconomic groups in South Asia," says co-senior author Ayushi Nayak of the Max Planck Institute for the Science of Human History. "In contrast, the individuals with eastern Mediterranean-related ancestry appear to have consumed a diet with very little millet."

Two major groups at Roopkund Lake date to 1000 years apart, with the more recent around 1800 AD

The findings also revealed a second surprise about the skeletons of Roopkund Lake. Radiocarbon dating indicates that the skeletons were not deposited at the same time, as previously assumed. Instead, the study finds that the two major genetic groups were actually deposited approximately 1000 years apart. First, during the 7th-10th centuries CE, individuals with Indian-related ancestry died at Roopkund, possibly during several distinct events. It was not until sometime during the 17th-20th centuries that the other two groups, likely composed of travelers from the eastern Mediterranean and Southeast Asia arrived at Roopkund Lake. “This finding shows the power of radiocarbon dating, as it had previously been assumed that the skeletons of Roopkund Lake were the result of a single catastrophic event,” says co-senior author Douglas J. Kennett of the University of California, Santa Barbara.

"It is still not clear what brought these individuals to Roopkund Lake or how they died," says Rai. “We hope that this study represents the first of many analyses of this mysterious site."

"Through the use of biomolecular analyses, such as ancient DNA, stable isotope dietary reconstruction, and radiocarbon dating, we discovered that the history of Roopkund Lake is more complex than we ever anticipated, and raises the striking question of how migrants from the eastern Mediterranean, who have an ancestry profile that is extremely atypical of the region today, died in this place only a few hundred years ago," concludes co-senior author David Reich of Harvard Medical School. "This study highlights the power of biomolecular tools to provide unexpected insights into our past.

Contacts and sources:
Anne Gibson
The Max Planck Institute for the Science of Human History (MPI-SHH)

Éadaoin Harney
Department of Organismic and Evolutionary Biology
Harvard University

Citation: Ancient DNA from the skeletons of Roopkund Lake reveals Mediterranean migrants in India,
Éadaoin Harney, Ayushi Nayak, Nick Patterson, Pramod Joglekar, Veena Mushrif-Tripathy, Swapan Mallick, Nadin Rohland, Jakob Sedig, Nicole Adamski, Rebecca Bernardos, Nasreen Broomandkhoshbacht, Brendan J. Culleton, Matthew Ferry, Thomas K. Harper, Megan Michel, Jonas Oppenheimer, Kristin Stewardson, Zhao Zhang, Harashawaradhana, Maanwendra Singh Bartwal, Sachin Kumar, Subhash Chandra Diyundi, Patrick Roberts, Nicole Boivin, Douglas J. Kennett, Kumarasamy Thangaraj, David Reich & Niraj Rai, Nature Communications, DOI:

Materials Revolutionize How Light Is Harnessed for Solar Energy

Researchers at Columbia University have developed a way to harness more power from singlet fission to increase the efficiency of solar cells, providing a tool to help push forward the development of next-generation devices.

Magnetic field data that shows the formation and decay of the excitons generated by singlet fission.
 Credit: A. Asadpoor Darvish, McCamey Lab

In a study published this week in Nature Chemistry, the team details the design of organic molecules that are capable of generating two excitons per photon of light, a process called singlet fission. The excitons are produced rapidly and can live for much longer than those generated from their inorganic counterparts, which leads to an amplification of electricity generated per photon that is absorbed by a solar cell.

“We have developed a new design rule for singlet fission materials,” said Luis Campos, an associate professor of chemistry and one of three principal investigators on the study. “This has led us to develop the most efficient and technologically useful intramolecular singlet fission materials to date. These improvements will open the door for more efficient solar cells.”

All modern solar panels operate by the same process – one photon of light generates one exciton, Campos explained. The exciton can then be converted into electric current. However, there are some molecules that can be implemented in solar cells that have the ability to generate two excitons from a single photon – a process called singlet fission. These solar cells form the basis for next-generation devices, which are still at infancy. One of the biggest challenges of working with such molecules, though, is that the two excitons “live” for very short periods of time (tens of nanoseconds), making it difficult to harvest them as a form of electricity.

Principal Investigator Luis Campos, associate professor of chemistry. 
Credit: Campos Lab

In the current study, funded in part by the Office of Naval Research, Campos and colleagues designed organic molecules that can quickly generate two excitons that live much longer than the state-of-the-art systems. It is an advancement that can not only be used in next-generation solar energy production, but also in photocatalytic processes in chemistry, sensors, and imaging, Campos explained, as these excitons can be used to initiate chemical reactions, which can then be used by industry to make drugs, plastics, and many other types of consumer chemicals.

“Intramolecular singlet fission has been demonstrated by our group and others, but the resulting excitons were either generated very slowly, or they wouldn’t last very long,” Campos said. “This work is the first to show that singlet fission can rapidly generate two excitons that can live for a very long time. This opens the door to fundamentally study how these excitons behave as they sit on individual molecules, and also to understand how they can be efficiently put to work in devices that benefit from light-amplified signals.”

The team’s design strategy should also prove useful in separate areas of scientific study and have many other yet-unimaginable applications, he added.

Campos’ study co-authors are: Samuel Sanders and Andrew Pun, of Columbia University; Matthew Y. Sfeir, of City University of New York; and Amir Asadpoordarvish, of the University of New South Wales.

Contacts and sources:
Jessica Guenzel
Columbia University

Citation: Ultra-fast intramolecular singlet fission to persistent multiexcitons by molecular design.
Andrew B. Pun, Amir Asadpoordarvish, Elango Kumarasamy, Murad J. Y. Tayebjee, Daniel Niesner, Dane R. McCamey, Samuel N. Sanders, Luis M. Campos, Matthew Y. Sfeir. Nature Chemistry, 2019; DOI: 10.1038/s41557-019-0297-7

The Meat Allergy: UVA IDs Biological Changes Triggered by Tick Bites

A University of Virginia School of Medicine scientist has identified key immunological changes in people who abruptly develop an allergic reaction to mammalian meat, such as beef. His work also provides an important framework for other scientists to probe this strange, recently discovered allergy caused by tick bites.

The findings by UVA’s Loren Erickson, PhD, and his team offer important insights into why otherwise healthy people can enjoy meat all their lives until a hot slab of ground beef or a festive Fourth of July hot dog suddenly become potentially life-threatening. Symptoms of the meat allergy can range from mild hives to nausea and vomiting to severe anaphylaxis, which can result in death.

“We don’t know what it is about the tick bite that causes the meat allergy. And, in particular, we haven’t really understood the source of immune cells that produce the antibodies that cause the allergic reactions,” Erickson explained. “There’s no way to prevent or cure this food allergy, so we need to first understand the underlying mechanism that triggers the allergy so we can devise a new therapy.”

Meat Allergy Caused by Tick Bites

People who develop the allergy in response to the bite of the Lone Star tick often have to give up eating mammalian meat, including beef and pork, entirely. Even food that does not appear to contain meat can contain meat-based ingredients that trigger the allergy. That means people living with the meat allergy must be hyper-vigilant. (For one person’s experience with the meat allergy, visit UVA’s Making of Medicine blog.)

The allergy was first discovered by UVA’s Thomas Platts-Mills, MD, a renowned allergist who determined that people were suffering reactions to a sugar called alpha-gal found in mammalian meat. Exactly what is happening inside the body, though, has remained poorly understood. Erickson’s work, along with that of others at UVA, is changing that.

Erickson’s team in UVA’s Department of Microbiology, Immunology and Cancer Biology has found that people with the meat allergy have a distinctive form of immune cells known as B cells, and they have them in great numbers. These white blood cells produce antibodies that release chemicals that cause the allergic reaction to meat.

In addition, Erickson, a member of UVA’s Carter Immunology Center, has developed a mouse model of the meat allergy so that scientists can study the mysterious allergy more effectively.

“This is the first clinically relevant model that I know of, so now we can go and ask a lot of these important questions,” he said. “We can actually use this model to identify underlying causes of the meat allergy that may inform human studies. So it’s sort of a back-and-forth of experiments that you can do in animal models that you can’t do in humans. But you can identify potential mechanisms that could lead to new therapeutic strategies so that we can go back to human subjects and test some of those hypotheses.”
Findings Published

Erickson describes the new meat allergy model in an article in the Journal of Immunology. The research team consisted of Jessica L. Chandrasekhar, Kelly M. Cox, William M. Loo, Hui Qiao, Kenneth S. Tung and Erickson. Tung and Erickson are both part of UVA’s Carter Center.

Contacts and sources:
Joshua Barney
University of Virginia Health System

Stone Age Boat Building Site Discovered Underwater

The Maritime Archaeological Trust has discovered a new 8,000 year old structure next to what is believed to be the oldest boat building site in the world on the Isle of Wight.

Director of the Maritime Archaeological Trust, Garry Momber, said “This new discovery is particularly important as the wooden platform is part of a site that doubles the amount of worked wood found in the UK from a period that lasted 5,500 years.”

Garry Momber tagging structure
Credit: National Oceanography Centre, UK

The site lies east of Yarmouth, and the new platform is the most intact, wooden Middle Stone Age structure ever found in the UK. The site is now 11 meters below sea level and during the period there was human activity on the site, it was dry land with lush vegetation. Importantly, it was at a time before the North Sea was fully formed and the Isle of Wight was still connected to mainland Europe.

The site was first discovered in 2005 and contains an arrangement of trimmed timbers that could be platforms, walkways or collapsed structures. However, these were difficult to interpret until the Maritime Archaeological Trust used state of the art photogrammetry techniques to record the remains. During the late spring the new structure was spotted eroding from within the drowned forest. The first task was to create a 3D digital model of the landscape so it could be experienced by non-divers. It was then excavated by the Maritime Archaeological Trust during the summer and has revealed a cohesive platform consisting of split timbers, several layers thick, resting on horizontally laid round-wood foundations.

Garry continued “The site contains a wealth of evidence for technological skills that were not thought to have been developed for a further couple of thousand years, such as advanced wood working. This site shows the value of marine archaeology for understanding the development of civilisation.

Yet, being underwater, there are no regulations that can protect it. Therefore, it is down to our charity, with the help of our donors, to save it before it is lost forever.”

The Maritime Archaeological Trust is working with the National Oceanography Centre (NOC) to record and study, reconstruct and display the collection of timbers. Many of the wooden artefacts are being stored in the British Ocean Sediment Core Research facility (BOSCORF), operated by the National Oceanography Centre.

As with sediment cores, ancient wood will degrade more quickly if it is not kept in a dark, wet and cold setting. While being kept cold, dark and wet, the aim is to remove salt from within wood cells of the timber, allowing it to be analysed and recorded. This is important because archaeological information, such as cut marks or engravings, are most often found on the surface of the wood and are lost quickly when timber degrades. Once the timbers have been recorded and have desalinated, the wood can be conserved for display.

Dr Suzanne Maclachlan, the curator at BOSCORF, said “It has been really exciting for us to assist the Trust’s work with such unique and historically important artefacts. This is a great example of how the BOSCORF repository is able to support the delivery of a wide range of marine science.”

When diving on the submerged landscape Dan Snow, the history broadcaster and host of History Hit, one of the world's biggest history podcasts, commented that he was both awestruck by the incredible remains and shocked by the rate of erosion.

This material, coupled with advanced wood working skills and finely crafted tools suggests a European, Neolithic (New Stone Age) influence. The problem is that it is all being lost. As the Solent evolves, sections of the ancient land surface are being eroded by up to half a metre per year and the archaeological evidence is disappearing.

Research in 2019 was funded by the Scorpion Trust, the Butley Research Group, the Edward Fort Foundation and the Maritime Archaeology Trust. Work was conducted with the help of volunteers and many individuals who gave their time and often money, to ensure the material was recovered successfully.

Contacts and sources:
National Oceanography Centre, UK

New Insights into What May Go Awry in Brains of People with Alzheimer’s

More than three decades of research on Alzheimer’s disease have not produced any major treatment advances for those with the disorder, according to a UCLA expert who has studied the biochemistry of the brain and Alzheimer’s for nearly 30 years. “Nothing has worked,” said Steven Clarke, a distinguished professor of chemistry and biochemistry. “We’re ready for new ideas.” Now, Clarke and UCLA colleagues have reported new insights that may lead to progress in fighting the devastating disease.

Scientists have known for years that amyloid fibrils — harmful, elongated, water-tight rope-like structures — form in the brains of people with Alzheimer’s, and likely hold important clues to the disease. UCLA Professor David Eisenberg and an international team of chemists and molecular biologists reported in the journal Nature in 2005 that amyloid fibrils contain proteins that interlock like the teeth of a zipper. The researchers also reported their hypothesis that this dry molecular zipper is in the fibrils that form in Alzheimer’s disease, as well as in Parkinson’s disease and two dozen other degenerative diseases. Their hypothesis has been supported by recent studies.

Alzheimer’s disease, the most common cause of dementia among older adults, is an irreversible, progressive brain disorder that kills brain cells, gradually destroys memory and eventually affects thinking, behavior and the ability to carry out the daily tasks of life. More than 5.5 million Americans, most of whom are over 65, are thought to have dementia caused by Alzheimer’s.

The UCLA team reports in the journal Nature Communications that the small protein beta amyloid, also known as a peptide, that plays an important role in Alzheimer’s has a normal version that may be less harmful than previously thought and an age-damaged version that is more harmful.

Rebeccah Warmack, who was a UCLA graduate student at the time of the study and is its lead author, discovered that a specific version of age-modified beta amyloid contains a second molecular zipper not previously known to exist. Proteins live in water, but all the water gets pushed out as the fibril is sealed and zipped up. Warmack worked closely with UCLA graduate students David Boyer, Chih-Te Zee and Logan Richards; as well as senior research scientists Michael Sawaya and Duilio Cascio.

What goes wrong with beta amyloid, whose most common forms have 40 or 42 amino acids that are connected like a string of beads on a necklace?

The researchers report that with age, the 23rd amino acid can spontaneously form a kink, similar to one in a garden hose. This kinked form is known as isoAsp23. The normal version does not create the stronger second molecular zipper, but the kinked form does.

“Now we know a second water-free zipper can form, and is extremely difficult to pry apart,” Warmack said. “We don’t know how to break the zipper.”

The normal form of beta amyloid has six water molecules that prevent the formation of a tight zipper, but the kink ejects these water molecules, allowing the zipper to form.

When one of its amino acids forms a kink, beta amyloid creates a harmful molecular zipper, shown here in green.

Rebeccah Warmack/UCLA

“Rebeccah has shown this kink leads to faster growth of the fibrils that have been linked to Alzheimer’s disease,” said Clarke, who has conducted research on biochemistry of the brain and Alzheimer’s disease since 1990. “This second molecular zipper is double trouble. Once it’s zipped, it’s zipped, and once the formation of fibrils starts, it looks like you can’t stop it. The kinked form initiates a dangerous cascade of events that we believe can result in Alzheimer’s disease.”

Why does beta amyloid’s 23rd amino acid sometimes form this dangerous kink?

Clarke thinks the kinks in this amino acid form throughout our lives, but we have a protein repair enzyme that fixes them.

“As we get older, maybe the repair enzyme misses the repair once or twice,” he said. “The repair enzyme might be 99.9% effective, but over 60 years or more, the kinks eventually build up. If not repaired or if degraded in time, the kink can spread to virtually every neuron and can do tremendous damage.”

“The good news is that knowing what the problem is, we can think about ways to solve it,” he added. “This kinked amino acid is where we want to look.”

The research offers clues to pharmaceutical companies, which could develop ways to prevent formation of the kink or get the repair enzyme to work better; or by designing a cap that would prevent fibrils from growing.

Clarke said beta amyloid and a much larger protein tau — with more than 750 amino acids — make a devastating one-two punch that forms fibrils and spreads them to many neurons throughout the brain. All humans have both beta amyloid and tau. Researchers say it appears that beta amyloid produces fibrils that can lead to tau aggregates, which can spread the toxicity to other brain cells. However, exactly how beta amyloid and tau work together to kill neurons is not yet known.

 Research by UCLA professor Steven Clarke and former graduate student Rebeccah Warmack, as well as UCLA colleagues, reveals new information about the brain’s biochemistry.
Steven Clarke, Rebeccah Warmack
Credit: Reed Hutchinson/UCLA

In this study, Warmack produced crystals, both the normal and kinked types, in 15 of beta amyloid’s amino acids. She used a modified type of cryo-electron microscopy to analyze the crystals. Cryo-electron microscopy, whose development won its creators the 2017 Nobel Prize in chemistry, enables scientists to see large biomolecules in extraordinary detail. Professor Tamir Gonen pioneered the modified microscopy, called microcrystal electron diffraction, which enables scientists to study biomolecules of any size.

Eisenberg is UCLA’s Paul D. Boyer Professor of Molecular Biology and a Howard Hughes Medical Institute investigator. Other researchers are co-author Gonen, a professor of biological chemistry and physiology at the UCLA David Geffen School of Medicine and a Howard Hughes Medical Institute investigator; and Jose Rodriguez, assistant professor of chemistry and biochemistry who holds the Howard Reiss Career Development Chair.

The research was funded by the National Science Foundation, National Institutes of Health, Howard Hughes Medical Institute, and the UCLA Longevity Center’s Elizabeth and Thomas Plott Chair in Gerontology, which Clarke held for five years.

Contacts and sources:
Stuart Wolpert
University of California - Los Angeles

Citation: Structure of amyloid-β (20-34) with Alzheimer’s-associated isomerization at Asp23 reveals a distinct protofilament interface.
Rebeccah A. Warmack, David R. Boyer, Chih-Te Zee, Logan S. Richards, Michael R. Sawaya, Duilio Cascio, Tamir Gonen, David S. Eisenberg, Steven G. Clarke. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-11183-z

Stardust Discovered in the Antarctic snow

The rare isotope iron-60 is created in massive stellar explosions. Only a very small amount of this isotope reaches the earth from distant stars. Now, a research team with significant involvement from the Technical University of Munich (TUM) has discovered iron-60 in Antarctic snow for the first time. The scientists suggest that the iron isotope comes from the interstellar neighborhood.

The quantity of cosmic dust that trickles down to Earth each year ranges between several thousand and ten thousand tons. Most of the tiny particles come from asteroids or comets within our solar system. However, a small percentage comes from distant stars. There are no natural terrestrial sources for the iron-60 isotope contained therein; it originates exclusively as a result of supernova explosions or through the reactions of cosmic radiation with cosmic dust.

The Kohnen Station is a container settlement in the Antarctic, from whose vicinity the snow samples in which iron-60 was found originate
.The Kohnen Station is a container settlement in the Antarctic, from whose vicinity the snow samples in which iron-60 was found originate.
Image: Martin Leonhardt / Alfred-Wegener-Institut (AWI)

Antarctic snow travels around the world

The first evidence of the occurrence of iron-60 on Earth was discovered in deep-sea deposits by a TUM research team 20 years ago. Among the scientists on the team was Dr. Gunther Korschinek, who hypothesized that traces of stellar explosions could also be found in the pure, untouched Antarctic snow. In order to verify this assumption, Dr. Sepp Kipfstuhl from the Alfred Wegener Institute collected 500 kg of snow at the Kohnen Station, a container settlement in the Antarctic, and had it transported to Munich for analysis. There, a TUM team melted the snow and separated the meltwater from the solid components, which were processed at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) using various chemical methods, so that the iron needed for the subsequent analysis was present in the milligram range, and the samples could be returned to Munich.

Korschinek and Dominik Koll from the research area Nuclear, Particle and Astrophysics at TUM found five iron-60 atoms in the samples using the accelerator laboratory in Garching near Munich. “Our analyses allowed us to rule out cosmic radiation, nuclear weapons tests or reactor accidents as sources of the iron-60," states Koll. “As there are no natural sources for this radioactive isotope on Earth, we knew that the iron-60 must have come from a supernova."

Stardust comes from the interstellar neighborhood

The research team was able to make a relatively precise determination as to when the iron-60 has been deposited on Earth: The snow layer that was analyzed was not older than 20 years. Moreover, the iron isotope that was discovered did not seem to come from particularly distant stellar explosions, as the iron-60 dust would have dissipated too much throughout the universe if this had been the case. Based on the half-life of iron-60, any atoms originating from the formation of the Earth would have completely decayed by now. Koll therefore assumes that the iron-60 in the Antarctic snow originates from the interstellar neighborhood, for example from an accumulation of gas clouds in which our solar system is currently located.

"Our solar system entered one of these clouds approximately 40,000 years ago," says Korschinek, "and will exit it in a few thousand years. If the gas cloud hypothesis is correct, then material from ice cores older than 40,000 years would not contain interstellar iron-60,” adds Koll. "This would enable us to verify the transition of the solar system into the gas cloud – that would be a groundbreaking discovery for researchers working on the environment of the solar system.

Contacts and sources:
Technical University of Munich (TUM)

Citation: Interstellar Fe60 in Antarctica
Dominik Koll, Gunther Korschinek, Thomas Faestermann, J. M. Gómez-Guzmán, Sepp Kipfstuhl, Silke Merchel, Jan M. Welch. . Physical Review Letters, 2019; 123 (7) DOI: 10.1103/PhysRevLett.123.072701

Sunday, August 18, 2019

Global Urban Water Scarcity Endures as a ‘Daily Reality’

Urban water provision is a social good, but one that will become increasingly difficult for cities and water utilities to provide due to climate change and population growth. More than 40% of residents in 15 cities in the “global south” – developing nations in Sub-Saharan Africa, South Asia and Latin America – still lack quality, affordable water that can be piped into dwellings, according to a report released by the World Resources Institute’s Ross Center for Sustainable Cities.

“Cities need to rethink how they view equitable access to water,” said report co-author Victoria Beard, professor of city and regional planning at Cornell University and a fellow at the World Resources Institute.

Ratio of total annual water withdrawals to total available annual renewable supply, accounting for upstream consumptive use. 
Baseline water stress.jpg
Credit: Source: World Resources Institute (WRI)

“In many developing countries … urban residents lack access to safe, reliable and affordable water on a daily basis, ” said Beard, also a fellow at Cornell’s Atkinson Center for a Sustainable Future. “These are the same countries that have made huge strides in guaranteeing universal access to primary education. Equitable access to water requires similar levels of political commitment. The solutions are not high tech. We know what needs to be done.”

In addition to Beard, the report – “Unaffordable and Undrinkable: Rethinking Urban Water Access in the Global South” – was prepared by lead author Diana Mitlin, professor, Manchester University; David Satterthwaite, senior fellow, the International Institute for Environment and Development; and Jillian Du, research analyst, WRI Ross Center for Sustainable Cities.

The authors analyzed data from 15 cities from the global south and found that, on average, 58% of households have water piped into their home dwelling or plot. In Latin America, about 97% of urban households had running water, while South Asia had 63% and sub-Saharan Africa had 22% – and often the water was poor quality.

Lack of access to piped-in water means that families must purchase water from private sources (tanker trucks, vendors) or buy bottled water, which can cost up to 52 times as much as piped utility water, Beard said.

When water is either unavailable or too expensive, households in these countries are forced into tough decisions, Beard said.

“Families will sacrifice their health and time to self-provide ‘free’ – but likely unsafe – ground and surface water, or they will buy water that requires financial cutbacks on food, electricity, education, health care or other household needs,” she said. “’Day Zero’ [a phrase that denotes water scarcity or a complete lack of water] is a daily reality for nearly half the population in many cities in the global south.”

The report offers four general solutions:
  • Extending a municipal piped water system to all households or plots;
  • Addressing intermittent water service to reduce contamination;
  • Implementing diverse strategies to make water affordable; and
  • Supporting citywide upgrading of informal settlements around the world, to improve rather than displace urban residents.

Beard said reports over the past decade have claimed that society had turned the corner on delivery of water to fulfill basic human needs in the global south. But in her own observations, she explained, data showed that the urban water crisis remains a problem.

Said Beard: “Widely used global indicators used to monitor water access have failed to capture the everyday reality on the ground in urban neighborhoods.”

Decades of attempts to increase the private sector’s role in water provision and corporatize water utilities have not adequately improved access, especially for the urban under-served. Cities and urban change agents should commit to providing equitable access to safe, reliable, and affordable water

Contacts and sources:
World Resources Institute
Cornell University

Early Species Developed Much Faster Than Previously Thought

When Earth's species were rapidly diversifying nearly 500 million years ago, that evolution was driven by complex factors including global cooling, more oxygen in the atmosphere, and more nutrients in the oceans. But it took a combination of many global environmental and tectonic changes occurring simultaneously and combining like building blocks to produce rapid diversification into new species, according to a new study by Dr. Alycia Stigall, Professor of Geological Sciences at Ohio University.

She and fellow researchers have narrowed in a specific time during an era known as the Ordovician Radiation, showing that new species actually developed rapidly during a much shorter time frame than previously thought. The Great Biodiversification Event where many new species developed, they argue, happened during the Darriwilian Stage about 465 million years ago. Their research, "Coordinated biotic and abiotic change during the Great Ordovician Biodiversification Event: Darriwilian assembly of early Paleozoic building blocks," was published in Palaeogeography, Palaeoclimatology, Palaeoecology as part of a special issue they are editing on the Great Ordovician Biodiversification Event.

Building block model of the earth system that produced the Great Ordovician Biodiversificaiton Event. 
Building block model of the earth system that produced the Great Ordovician Biodiversificaiton Event. Figure from Stigall et al., 2019.
Figure from Stigall et al., 2019.

New datasets have allowed them to show that what previously looked like species development widespread over time and geography was actually a diversification pulse. Picture a world before the continents as we know them, when most of the land mass was south of the equator, with only small continents and islands in the vast oceans above the tropics. Then picture ice caps forming over the southern pole. As the ice caps form, the ocean recedes and local, isolated environments form around islands and in seas perched atop continents. In those shallow marine environments, new species develop.

Then picture the ice caps melting and the oceans rising again, with those new species riding the waves of global diversification to populate new regions. The cycle then repeats producing waves of new species and new dispersals.

Lighting the Spark of Diversification

The early evolution of animal life on Earth is a complex and fascinating subject. The Cambrian Explosion (between about 540 to 510 million years ago) produced a stunning array of body plans, but very few separate species of each, notes Stigall. But nearly 40 million years later, during the Ordovician Period, this situation changed, with a rapid radiation of species and genera during the Great Ordovician Biodiversification Event.

The triggers of the GOBE and processes that promoted diversification have been subject to much debate, but most geoscientists haven't fully considered how changes like global cooling or increased oxygenation would foster increased diversification.

A recent review paper by Stigall and an international team of collaborators attempts to provide clarity on these issues. For this study, Stigall teamed up with Cole Edwards (Appalachian State University), a sedimentary geochemist, and fellow paleontologists Christian Mac Ørum Rasmussen (University of Copenhagen) and Rebecca Freeman (University of Kentucky) to analyze how changes to the physical earth system during the Ordovician could have promoted this rapid increase in diversity.

In their paper, Stigall and colleagues demonstrate that the main pulse of diversification during the GOBE is temporally restricted and occurred in the Middle Ordovician Darriwilian Stage (about 465 million years ago). Many changes to the physical earth system, including oceanic cooling, increased nutrient availability, and increased atmospheric oxygen accumulate in the interval leading up to the Darriwilian.

These physical changes were necessary building blocks, but on their own were not enough to light the spark of diversification.

The missing ingredient was a method to alternately connect and isolate populations of species through cycles of vicariance and dispersal. That spark finally occurs in the Darriwilian Stage when ice caps form over the south pole of the Ordovician Earth. The waxing and waning of these ice sheets caused sea level to rise and fall (similar to the Pleistocene), which provided the alternate connection and disconnection needed to facilitate rapid diversity accumulation.

Stigall and her collaborators compared this to the assembly of building blocks required to pass a threshold.

Contacts and sources:
Ohio University

Citation: Coordinated biotic and abiotic change during the Great Ordovician Biodiversification Event: Darriwilian assembly of early Paleozoic building blocks
 Alycia L.StigallCole T. Edwards, Rebecca L.FreemanChristian M.Ø.Rasmussen   Palaeogeography, Palaeoclimatology, Palaeoecology Volume 530, 15 September 2019, Pages 249-270

Wearable Sensors Detect What’s in Your Sweat

Needle pricks not your thing? A team of scientists at the University of California, Berkeley, is developing wearable skin sensors that can detect what’s in your sweat.

New wearable sensors developed by scientists at UC Berkeley can provide real-time measurements of sweat rate and electrolytes and metabolites in sweat. 
A close up shot of a new sweat sensor on a person's forehead
Photo by Bizen Maskey, Sunchon National University

They hope that one day, monitoring perspiration could bypass the need for more invasive procedures like blood draws, and provide real-time updates on health problems such as dehydration or fatigue.

In a paper appearing (Friday, August 16) in Science Advances, the team describes a new sensor design that can be rapidly manufactured using a “roll-to-roll” processing technique that essentially prints the sensors onto a sheet of plastic like words on a newspaper.

They used the sensors to monitor the sweat rate, and the electrolytes and metabolites in sweat, from volunteers who were exercising, and others who were experiencing chemically induced perspiration.

“The goal of the project is not just to make the sensors but start to do many subject studies and see what sweat tells us — I always say ‘decoding’ sweat composition,” said Ali Javey, a professor of electrical engineering and computer science at UC Berkeley and senior author on the paper.

“For that we need sensors that are reliable, reproducible, and that we can fabricate to scale so that we can put multiple sensors in different spots of the body and put them on many subjects,” said Javey, who also serves as a faculty scientist at Lawrence Berkeley National Laboratory.

The sensors can be rapidly manufactured using a roll-to-roll processing technique that prints the sensors onto a sheet of plastic.
 Photo by Antti Veijola, VTT

The new sensors contain a spiraling microscopic tube, or microfluidic, that wicks sweat from the skin. By tracking how fast the sweat moves through the microfluidic, the sensors can report how much a person is sweating, or their sweat rate.

The microfluidics are also outfitted with chemical sensors that can detect concentrations of electrolytes like potassium and sodium, and metabolites like glucose.

Javey and his team worked with researchers at the VTT Technical Research Center of Finland to develop a way to quickly manufacture the sensor patches in a roll-to-roll processing technique similar to screen printing.

“Roll-to-roll processing enables high-volume production of disposable patches at low cost,” Jussi Hiltunen of VTT said. “Academic groups gain significant benefit from roll-to-roll technology when the number of test devices is not limiting the research. Additionally, up-scaled fabrication demonstrates the potential to apply the sweat-sensing concept in practical applications.”

To better understand what sweat can say about the real-time health of the human body, the researchers first placed the sweat sensors on different spots on volunteers’ bodies — including the forehead, forearm, underarm and upper back — and measured their sweat rates and the sodium and potassium levels in their sweat while they rode on an exercise bike.

They found that local sweat rate could indicate the body’s overall liquid loss during exercise, meaning that tracking sweat rate might be a way to give athletes a heads up when they may be pushing themselves too hard.

“Traditionally what people have done is they would collect sweat from the body for a certain amount of time and then analyze it,” said Hnin Yin Yin Nyein, a graduate student in materials science and engineering at UC Berkeley and one of the lead authors on the paper. “So you couldn’t really see the dynamic changes very well with good resolution. Using these wearable devices we can now continuously collect data from different parts of the body, for example to understand how the local sweat loss can estimate whole-body fluid loss.”

They also used the sensors to compare sweat glucose levels and blood glucose levels in healthy and diabetic patients, finding that a single sweat glucose measurement cannot necessarily indicate a person’s blood glucose level.

“There’s been a lot of hope that non-invasive sweat tests could replace blood-based measurements for diagnosing and monitoring diabetes, but we’ve shown that there isn’t a simple, universal correlation between sweat and blood glucose levels,” said Mallika Bariya, a graduate student in materials science and engineering at UC Berkeley and the other lead author on the paper. “This is important for the community to know, so that going forward we focus on investigating individualized or multi-parameter correlations.”

Ali Javey describes an earlier version of his lab’s wearable sweat sensor in this video from 2016. (UC Berkeley video by Roxanne Makasdjian and Stephen McNally)

Co-authors on the paper include Liisa Kivimaki, Sanna Uusitalo, Elina Jansson, Tuomas Happonen and Christina Liedert of the VTT Technical Research Center of Finland; and Tiffany Sun Liaw, Christine Heera Ahn, John A. Hangasky, Jianqi Zhao, Yuanjing Lin, Minghan Chao, Yingbo Zhao and Li-Chia Tai of UC Berkeley.

This work was supported by the NSF Nanomanufacturing Systems for Mobile Computing and Mobile Energy Technologies (NASCENT), the Berkeley Sensor and Actuator Center (BSAC), and the Bakar fellowship.

Contacts and sources:
Kara Manke
University of California, Berkeley

Citation: Regional and correlative sweat analysis using high-throughput microfluidic sensing patches toward decoding sweat
Hnin Yin Yin Nyein1,2,3,*, Mallika Bariya1,2,3,*, Liisa Kivimäki4, Sanna Uusitalo4, Tiffany Sun Liaw1, Elina Jansson4, Christine Heera Ahn1, John A. Hangasky5, Jiangqi Zhao1,3, Yuanjing Lin1,3, Tuomas Happonen4, Minghan Chao1, Christina Liedert4, Yingbo Zhao1,3, Li-Chia Tai1,2,3, Jussi Hiltunen4 and Ali Javey1,2,3,†

1Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA 94720, USA.
2Berkeley Sensor and Actuator Center, University of California, Berkeley, Berkeley, CA 94720, USA.
3Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA 94720, USA.
4VTT-Technical Research Centre of Finland, Kaitoväylä 1, FIN-90590 Oulu, Finland.
5California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, CA 94720, USA.
* These authors contributed equally to this work.
Science Advances 16 Aug 2019:
Vol. 5, no. 8, eaaw9906
DOI: 10.1126/sciadv.aaw9906

Saturday, August 17, 2019

Soft Robot Exoskeleton Makes Running and Walking Easier

A versatile, portable exosuit that assists both walking and running highlights the potential for lightweight and non-restrictive wearable robots outside the lab
 Credit: Wyss Institute at Harvard University

Between walking at a leisurely pace and running for your life, human gaits can cover a wide range of speeds. Typically, we choose the gait that allows us to consume the least amount of energy at a given speed. For example, at low speeds, the metabolic rate of walking is lower than that of running in a slow jog; vice versa at high speeds, the metabolic cost of running is lower than that of speed walking.

Researchers in academic and industry labs have previously developed robotic devices for rehabilitation and other areas of life that can either assist walking or running, but no untethered portable device could efficiently do both. Assisting walking and running with a single device is challenging because of the fundamentally different biomechanics of the two gaits. However, both gaits have in common an extension of the hip joint, which starts around the time when the foot comes in contact with the ground and requires considerable energy for propelling the body forward.

 This video shows demonstrates the use of the hip-assisting exosuit in different natural environments, and shows how the robotic device senses changes in the gait-specific vertical movements of the center of mass during walking and running to rapidly adjust its actuation.

 Credit: Wyss Institute at Harvard University

As reported today in Science, a team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS), and the University of Nebraska Omaha now has developed a portable exosuit that assists with gait-specific hip extension during both walking and running. Their lightweight exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which is controlled by an algorithm that can robustly detect the transition from walking to running and vice versa.

The team first showed that the exosuit worn by users in treadmill-based indoor tests, on average, reduced their metabolic costs of walking by 9.3% and of running by 4% compared to when they were walking and running without the device. “We were excited to see that the device also performed well during uphill walking, at different running speeds and during overground testing outside, which showed the versatility of the system,” said Conor Walsh, Ph.D., who led the study. Walsh is a Core Faculty member of the Wyss Institute, the Gordon McKay Professor of Engineering and Applied Sciences at SEAS, and Founder of the Harvard Biodesign Lab. “While the metabolic reductions we found are modest, our study demonstrates that it is possible to have a portable wearable robot assist more than just a single activity, helping to pave the way for these systems to become ubiquitous in our lives,” said Walsh.

The hip exosuit was developed as part of the Defense Advanced Research Projects Agency (DARPA)’s former Warrior Web program and is the culmination of years of research and optimization of the soft exosuit technology by the team. A previous multi-joint exosuit developed by the team could assist both the hip and ankle during walking, and a medical version of the exosuit aimed at improving gait rehabilitation for stroke survivors is now commercially available in the US and Europe, via a collaboration with ReWalk Robotics.

The light-weight versatile exosuit assists hip extension during uphill walking and at different running speeds in natural terrain.
 Credit: Wyss Institute at Harvard University

The team’s most recent hip-assisting exosuit is designed to be simpler and lighter weight compared to their past multi-joint exosuit. It assists the wearer via a cable actuation system. The actuation cables apply a tensile force between the waist belt and thigh wraps to generate an external extension torque at the hip joint that works in concert with the gluteal muscles. The device weighs 5kg in total with more than 90% of its weight located close to the body’s center of mass. “This approach to concentrating the weight, combined with the flexible apparel interface, minimizes the energetic burden and movement restriction to the wearer,” said co-first-author Jinsoo Kim, a SEAS graduate student in Walsh’s group. “This is important for walking, but even more so for running as the limbs move back and forth much faster.” Kim shared the first-authorship with Giuk Lee, Ph.D., a former postdoctoral fellow on Walsh’s team and now Assistant Professor at Chung-Ang University in Seoul, South Korea.

A major challenge the team had to solve was that the exosuit needed to be able to distinguish between walking and running gaits and change its actuation profiles accordingly with the right amount of assistance provided at the right time of the gait cycle.

To explain the different kinetics during the gait cycles, biomechanists often compare walking to the motions of an inverted pendulum and running to the motions of a spring-mass system. During walking, the body’s center of mass moves upward after heel-strike, then reaches maximum height at the middle of the stance phase to descend towards the end of the stance phase. In running, the movement of the center of mass is opposite. It descends towards a minimum height at the middle of the stance phase and then moves upward towards push-off.

The team’s portable exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which uses an algorithm that robustly predicts tran
sitions between walking and running gaits. 

Credit: Wyss Institute at Harvard University

“We took advantage of these biomechanical insights to develop our biologically inspired gait classification algorithm that can robustly and reliably detect a transition from one gait to the other by monitoring the acceleration of an individual’s center of mass with sensors that are attached to the body,” said co-corresponding author Philippe Malcolm, Ph.D., Assistant Professor at University of Nebraska Omaha. “Once a gait transition is detected, the exosuit automatically adjusts the timing of its actuation profile to assist the other gait, as we demonstrated by its ability to reduce metabolic oxygen consumption in wearers.”

In ongoing work, the team is focused on optimizing all aspects of the technology, including further reducing weight, individualizing assistance and improving ease of use. “It is very satisfying to see how far our approach has come,” said Walsh, “and we are excited to continue to apply it to a range of applications, including assisting those with gait impairments, industry workers at risk of injury performing physically strenuous tasks, or recreational weekend warriors.”

“This breakthrough study coming out of the Wyss Institute’s Bioinspired Soft Robotics platform gives us a glimpse into a future where wearable robotic devices can improve the lives of the healthy, as well as serve those with injuries or in need of rehabilitation,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School, the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

Other authors on the study are past and present members of Walsh’s team, including data analyst Roman Heimgartner; Research Fellow Dheepak Arumukhom Revi; Control Engineer Nikos Karavas, Ph.D.; Functional Apparel Designer Danielle Nathanson; Robotics Engineer Ignacio Galiana, Ph.D.; Robotics Engineer Asa Eckert-Erdheim; Electromechanical Engineer Patrick Murphy; Engineer David Perry; Software Engineer Nicolas Menard, and graduate student Dabin Kim Choe. The study was funded by the Defense Advanced Research Projects Agency’s Warrior Web Program, the National Science Foundation and Harvard’s Wyss Institute for Biologically Inspired Engineering.

Contacts and sources:
Benjamin Boettner
Wyss Institute for Biologically Inspired Engineering at Harvard

Citation: Reducing the metabolic rate of walking and running with a versatile, portable exosuit
Jinsoo Kim, Giuk Lee, Roman Heimgartner, Dheepak Arumukhom Revi, Nikos Karavas, Danielle Nathanson, Ignacio Galiana, Asa Eckert-Erdheim, Patrick Murphy, David Perry, Nicolas Menard, Dabin Kim Choe, Philippe Malcolm, Conor J. Walsh. . Science, 2019 DOI: 10.1126/science.aav7536

Friday, August 16, 2019

Reading Invisible Writings of the Egyptians Now Possible

The first thing that catches an archaeologist's eye on the small piece of papyrus from Elephantine Island on the Nile is the apparently blank patch. Researchers from the Egyptian Museum, Berlin universities and Helmholtz-Zentrum Berlin have now used the synchrotron radiation from BESSY II to unveil its secret. This pushes the door wide open for analysing the giant Berlin papyrus collection and many more.

For more than a century, numerous metal crates and cardboard boxes have sat in storage at the Egyptian Museum and Papyrus Collection Berlin, all of which were excavated by Otto Rubensohn from 1906 to 1908 from an island called Elephantine on the River Nile in the south of Egypt, near the city of Aswan. Eighty percent of the texts on the papyrus in these containers have yet to be studied, and this can hardly be done using conventional methods anymore. Thousands of years ago, the Egyptians would carefully roll up or fold together letters, contracts and amulets to a tiny size so that they would take up the least possible space. In order to read them, the papyri would have to be just as carefully unfolded again.

 "Today, however, much of this papyrus has aged considerably, so the valuable texts can easily crumble if we try to unfold or unroll them," Prof. Dr. Heinz-Eberhard Mahnke of Helmholtz-Zentrum Berlin and Freie Universität Berlin describes the greatest obstacle facing the Egyptologists, who are eager to unearth the scientific treasures waiting in the boxes and crates in the Berlin Egyptian Museum.

Testing the fragile papyrus with nondestructive methods

The physicist at Helmholtz-Zentrum Berlin knew from many years of research how to analyse the fragile papyrus without destroying it: shining a beam of X-ray light on the specimen causes the atoms in the papyrus to become excited and send back X-rays of their own, much like an echo. Because the respective elements exhibit different X-ray fluorescence behaviour, the researchers can distinguish the atoms in the sample by the energy of the radiation they return. The scientists therefore long ago developed laboratory equipment that uses this X-ray fluorescence to analyse sensitive specimens without destroying them.

Credit: HZB

Scholars in ancient Egypt typically wrote with a black soot ink made from charred pieces of wood or bone and which consisted mainly of elemental carbon. "For certain purposes, however, the ancient Egyptians also used coloured inks containing elements such as iron, copper, mercury or lead," Heinz-Eberhard Mahnke explains. If the ancient Egyptian scribes had used such a "metal ink" to inscribe the part that now appears blank on the Elephantine papyrus, then X-ray fluorescence should be able to reveal traces of those metals. Indeed, using the equipment in their laboratory, the researchers were able to detect lead in the blank patch of papyrus.

Revealing sharper details at BESSY II with "absorption edge radiography"

In fact, they even managed to discern characters, albeit as a blurry image. To capture a much sharper image, they studied it with X-ray radiography at BESSY II, where the synchrotron radiation illuminates the specimen with many X-ray photons of high coherence. Using "absorption edge radiography" at the BAMline station of BESSY II, they were able to increase the brightness of this technique for the sample studied, and thus better distinguish the characters written on the papyrus from the structure of the ancient paper. So far, it has not been possible to translate the character, but it could conceivably depict a deity.

Composition of the invisible ink resolved in the Rathgen laboratory

The analysis at BESSY II did not identify the kind of leaded ink the ancient scribes used to write these characters on the papyrus. Only by using a "Fourier-transform infrared spectrometer" could the scientists of the Rathgen Research Laboratory Berlin finally identify the substance as lead carboxylate, which is in fact colourless. But why would the ancient scribe have wanted to write on the papyrus with this kind of "invisible ink"? "We suspect the characters may originally have been written in bright minium (red lead) or perhaps coal-black galena (lead glance)," says Heinz-Eberhard Mahnke, summarising the researchers' deliberations.

If such inks are exposed to sunlight for too long, the energy of the light can trigger chemical reactions that alter the colours. Even many modern dyes similarly fade over time in the bright sunlight. It is therefore easily conceivable that, over thousands of years, the bright red minium or jet black galena would transform into the invisible lead carboxylate, only to mystify researchers as a conspicuously blank space on the papyrus fragment.

Method developed to study folded papyri without contact

With their investigation, Dr. Tobias Arlt of Technische Universität Berlin, Prof. Dr. Heinz-Eberhard Mahnke and their colleagues have pushed the door wide open for future studies to decipher texts even on finely folded or rolled papyri from the Egyptian Museum without having to unfold them and risk destroying the precious finds. The researchers namely developed a new technique for virtually opening the valuable papyri on the computer without ever touching them.

The Elephantine project funded by the European Research Council, ERC, and headed by Prof. Dr. Verena Lepper (Stiftung Preußischer Kulturbesitz-Staatliche Museen zu Berlin) is thus well on its way to studying many more of the hidden treasures in the collection of papyrus in Berlin and other parts of the world, and thus to learning more about Ancient Egypt.

Contacts and sources: 
Dr. Heinz-Eberhard Mahnke, Silvia Zerbe
Helmholtz-Zentrum Berlin (HZB)

Citation:  "Absorption Edge Sensitive Radiography and Tomography of Egyptian Papyri". T. Arlt, H.-E. Mahnke T. Siopi, E. Menei, C. Aibéo, R.-R. Pausewein, I. Reiche, I. Manke, V. Lepper Published in the Journal of Cultural Heritage (2019):


"Virtual unfolding of folded papyri"; H.-E. Mahnke, T. Arlt, D. Baum, H.-C. Hege, F. Herter, N. Lindow, I. Manke, T. Siopi, E. Menei, M. Etienne, V. Lepper (