Shelter, safest air intake locations during urban pollution events identified

by Gabrielle Stewart, Pennsylvania State University FEBRUARY 5, 2020

Researchers at Penn State find that roofs and the downwind sides of buildings in street canyons have the lowest levels of particulate matter during a single-source pollution event. The findings have implications for improving evacuation plans during a pollution release as well as for informing ventilation system design of urban buildings.  Credit: PIXABAY

Roofs and the downwind sides of buildings in street canyons have the lowest levels of particulate matter during a single-source pollution event, according to Penn State researchers. The findings have implications for improving evacuation plans during a pollution release as well as for informing ventilation system design of urban buildings.

"Previous research has focused on ambient pollution created by traffic," said Jeremy Gernand, assistant professor of industrial health and safety. "We decided to investigate sources of pollution from a point source of particulate matter, such as a chemical spill or an accidental release from a factory."

The researchers investigated a pollutant release scenario to evaluate the safest locations for evacuation and for building design elements such as air intakes. This marks the first study investigating an emission event from a single source near a street canyon.

Monitoring air quality in urban areas can be very important due to high population density and levels of particulates. Street canyons, or places where the street is bounded on both sides by buildings, are important locations for studying air pollution because they are prevalent in urban areas.

Particulates, often referred to as aerosols, are fine solids or liquid droplets suspended in gas. High concentrations in the atmosphere can contribute to mortality rates, because exposure to these particles can exacerbate or cause adverse medical effects. Particulates are released from a variety of natural or human sources, such as cars, construction sites and dust storms.

Researchers in Penn State's Mining Ventilation Laboratory created a 3-D miniature street canyon in a wind tunnel using foam blocks to simulate buildings . Four foam blocks were placed in a two-by-two array, separated by gaps that served as streets.

To ensure the airflow within the wind tunnel matched realistic conditions in an urban area, researchers had to make adjustments. Typically, air in a wind tunnel exhibits laminar flow, meaning it flows smoothly in parallel layers with no eddies or crosscurrents that disrupt the direction of flow. This type of flow can be ideal for testing mechanisms such as airplane wings in simulated high-altitude air.

At lower elevations, however, air behaves very differently. Near the ground, smaller structures like houses and trees and larger buildings, such as skyscrapers, interrupt the smooth flow of air and cause it to become turbulent, or irregular and agitated.

The researchers used low-cost materials like Legos and cardboard spires to create turbulent airflow in a wind tunnel filled with laminar-flowing air.

To simulate a single particulate emission source, researchers used water generated from an ultrasonic humidifier. Because environmental particulates are frequently coated in water, the collisions between water droplets in a wind tunnel experiment and collisions between water-coated particulates outside can be very similar, Gernand said.

To find the areas in the street canyon where particulate levels reached their minimum and maximum concentrations, researchers used the data from the wind-tunnel experiment to create a computer model of the scenario. Computer simulations showed the lowest particulate concentrations were located at the roof and on downwind building facades. At breathing level, the lowest concentrations were found on the leeward—protected—side of the array's transverse channel, the street running perpendicular to the direction of airflow.

The findings have implications for improving evacuation plans and for informing ventilation system design. In the event of a pollution release emergency from a central source, pedestrians should be evacuated to the leeward side of the transverse channel. For installation of new air intakes, portions of roofs furthest away from inner channels, or roads, of street canyons serve as the safest location, the researchers said.

The researchers reported their findings in the journal Air Quality, Atmosphere and Health.

However, given the variety of possible scenarios, these findings represent only a general guideline and will benefit from further investigation, said Gernand. Building upon the cost-effective modeling approach used in this study, future research will consider additional possibilities with the goal of providing more comprehensive safety recommendations.

Researchers develop new bio-inspired wing design for small drones

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More information: Mengfan Li et al, Identifying shelter locations and building air intake risk from release of particulate matter in a three-dimensional street canyon via wind tunnel and CFD simulation, Air Quality, Atmosphere & Health (2019). DOI: 10.1007/s11869-019-00753-1

Bumble bees prefer a low-fat diet

by Technical University Munich FEBRUARY 5, 2020

Using a two-step mechanistical approach that included learning and feeding experiments, the group established a new way to literally keep a close eye on the feeding habits of insects. Credit: Dieter Mahsberg

Bees are an important factor for our environment and our sustenance. Without insect pollination, many plant species—including various crops—cannot reproduce. "Bee mortality therefore affects food supply for human beings," said Professor Sara Leonhardt, who specializes in plant-insect interactions. All of the worldwide more than 20,000 bee species need to be considered. Among these, bumble bees are of particular importance besides the famous honey bee.

"Bees obtain most of their nutrients from their main food sources, which are nectar and pollen. While nectar is mainly a source of carbohydrates, pollen contains most of the other necessary nutrients: proteins, fat, minerals and vitamins. Until today, most bee researchers assumed that bees, like other herbivores, mainly consider the protein content when choosing their food," Professor Leonhardt explained.

Using a two-step mechanistic approach that included learning and feeding experiments, the group established a new way to literally keep a close eye on the feeding habits of insects.

Learning experiments with bumble bees (Bombus terrestris)

Which nutrients can bumble bees taste in pollen? As a first step, learning experiments helped the scientists to establish the bumble bees' preference for certain nutrients—in this case fat and protein.

Fabian Rüdenauer, main author of the study, explained: "We are focusing on fatty and amino acids, which represent the two essential pollen macro nutrients and which are likely to be perceived and thus tasted by bees."

In this context, small amounts of fatty acids were added to pollen to increase its fat content. The researchers found that bumble bees could clearly differentiate between normal pollen and pollen with increased fat content and did show a clear preference for normal pollen. Surprisingly, the bumble bees made no clear distinction when the pollen amino acid content was altered in the same way.

The bumble bee collects pollen from a blue viper's head (Echium vulgare). Credit: Dieter Mahsberg

What is a bumble bee's preferred taste?

Which nutrients actually affect the bumble bees' foraging behavior and what are the consequences for their survival and reproductive capabilities? Those were the central questions guiding the subsequent feeding experiments.

"The more fat the pollen contained, the less the bumble bees consumed that pollen," Leonhardt concluded. Bumble bees actually accepted death over having to consume the high-fat pollen. The work group therefore concluded that fat in pollen adversely affects the bumble bees' reproductive capabilities and survival, which is why it is being avoided.

Similar to the learning experiment, variations in the amino acid content of pollen did not affect the bees' feeding habits, survival or reproduction.

Help for bees and bumble bees

"Our study highlights the importance of fat for foraging bumble bees. It also shows that there is a correlation between nutrient perception, nutritional regulation and reproductive fitness," stated Dr. Johannes Spaethe from the University of Würzburg, who also led the study. "The bees can taste what is good for them and collect their food accordingly," said Leonhardt, summarizing the results.

Currently, the researchers are creating a dataset on pollen nutritional chemistry in order to obtain an overview across the wide spectrum of different plant species. They are also examining the nutritional needs of other species of bees. "In the future, this may lead to better understanding the effect of variation in flowering plant species on bees, and it may improve protective measures such as flower strips in agricultural landscapes," predict the researchers.

Sunflower pollen has medicinal, protective effects on bees

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More information: Fabian A. Ruedenauer et al, Best be(e) on low fat: linking nutrient perception, regulation and fitness, Ecology Letters (2020). DOI: 10.1111/ele.13454

Global cooling after nuclear war would harm ocean life

by Rutgers University

Corals, which are threatened by global climate change and ocean acidification, support a wide range of reef fish at Baker reef in the Pacific Remote Islands. Credit: NOAA Fisheries/Morgan Winston

A nuclear war that cooled Earth could worsen the impact of ocean acidification on corals, clams, oysters and other marine life with shells or skeletons, according to the first study of its kind.

"We found that the ocean's chemistry would change, with global cooling dissolving atmospheric carbon into the upper ocean and exacerbating the primary threat of ocean acidification," said co-author Alan Robock, a Distinguished Professor in the Department of Environmental Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick.

The study is published in the journal Geophysical Research Letters.

Scientists looked at how climate changes stemming from nuclear war would affect the oceans. They used a global climate model in which the climate reacted to soot (black carbon) in smoke that would be injected into the upper atmosphere from fires ignited by nuclear weapons. They considered a range of hypothetical nuclear wars, including a relatively small one between India and Pakistan and a large one between the United States and Russia.

Excess carbon dioxide from the burning of fossil fuels enters the ocean and reacts with water to form carbonic acid, which decreases ocean pH (makes it more acidic) and lowers levels of carbonate ions. Corals, clams, oysters and other marine organisms use carbonate ions to create their shells and skeletons, according to the National Oceanic and Atmospheric Administration. A more acidic ocean makes it harder to form and maintain shells and skeletons.

The massive amount of smoke from a nuclear conflict would block sunlight and cause global cooling. The cooling would temporarily boost the pH in the surface ocean over five years and briefly lessen the decline in pH from ocean acidification. But the cooling would also lead to lower levels of carbonate ions for about 10 years, challenging shell maintenance in marine organisms.

"We have known for a while that agriculture on land would be severely affected by climate change from nuclear war," Robock said. "A lingering question is whether the survivors could still get food from the sea. Our study is the first step in answering this question."

The next step is to combine projected changes in ocean chemistry with projected changes in temperature and salinity and assess their impacts on shellfish and fish stocks throughout the oceans, he said.

Oysters as catch of the day? Perhaps not, if ocean acidity keeps rising

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More information: Nicole S. Lovenduski et al, The Potential Impact of Nuclear Conflict on Ocean Acidification, Geophysical Research Letters (2020). DOI: 10.1029/2019GL086246

Journal information: Geophysical Research Letters 

ALMA catches beautiful outcome of stellar fight

This new ALMA image shows the outcome of a stellar fight: a complex and stunning gas environment surrounding the binary HD101584. The colours represent speed, going from blue -- gas moving the fastest towards us -- to red -- gas moving the fastest away from us. Jets, almost along the line of sight, propel the material in blue and red. The stars in the binary are located at the single bright dot at the centre of the ring-like structure shown in green, which is moving with the same velocity as the system as a whole along the line of sight. Astronomers believe this ring has its origin in the material ejected as the lower mass star in the binary spiralled towards its red-giant partner. Credit: ALMA (ESO/NAOJ/NRAO), Olofsson et al. Acknowledgement: Robert Cumming

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, have spotted a peculiar gas cloud that resulted from a confrontation between two stars. One star grew so large it engulfed the other which, in turn, spiralled towards its partner provoking it into shedding its outer layers.

Like humans, stars change with age and ultimately die. For the Sun and stars like it, this change will take it through a phase where, having burned all the hydrogen in its core, it swells up into a large and bright red-giant star. Eventually, the dying Sun will lose its outer layers, leaving behind its core: a hot and dense star called a white dwarf.

"The star system HD101584 is special in the sense that this 'death process' was terminated prematurely and dramatically as a nearby low-mass companion star was engulfed by the giant," said Hans Olofsson of the Chalmers University of Technology, Sweden, who led a recent study, published in Astronomy & Astrophysics, of this intriguing object.

Thanks to new observations with ALMA, complemented by data from the ESO-operated Atacama Pathfinder EXperiment (APEX), Olofsson and his team now know that what happened in the double-star system HD101584 was akin to a stellar fight. As the main star puffed up into a red giant, it grew large enough to swallow its lower-mass partner. In response, the smaller star spiralled in towards the giant's core but didn't collide with it. Rather, this manoeuvre triggered the larger star into an outburst, leaving its gas layers dramatically scattered and its core exposed.

The team says the complex structure of the gas in the HD101584 nebula is due to the smaller star's spiralling towards the red giant, as well as to the jets of gas that formed in this process. As a deadly blow to the already defeated gas layers, these jets blasted through the previously ejected material, forming the rings of gas and the bright bluish and reddish blobs seen in the nebula.

A silver lining of a stellar fight is that it helps astronomers to better understand the final evolution of stars like the Sun. "Currently, we can describe the death processes common to many Sun-like stars, but we cannot explain why or exactly how they happen. HD101584 gives us important clues to solve this puzzle since it is currently in a short transitional phase between better studied evolutionary stages. With detailed images of the environment of HD101584 we can make the connection between the giant star it was before, and the stellar remnant it will soon become," says co-author Sofia Ramstedt from Uppsala University, Sweden.

Co-author Elizabeth Humphreys from ESO in Chile highlighted that ALMA and APEX, located in the country's Atacama region, were crucial to enabling the team to probe "both the physics and chemistry in action" in the gas cloud. She added: "This stunning image of the circumstellar environment of HD101584 would not have been possible without the exquisite sensitivity and angular resolution provided by ALMA."

While current telescopes allow astronomers to study the gas around the binary, the two stars at the centre of the complex nebula are too close together and too far away to be resolved. ESO's Extremely Large Telescope, under construction in Chile's Atacama Desert, "will provide information on the 'heart' of the object," says Olofsson, allowing astronomers a closer look at the fighting pair.

This research was presented in a paper published in Astronomy & Astrophysics. 

Primate venom sheds light on why so many people suffer cat allergies

by University of Queensland FEBRUARY 5, 2020

CC0 bySilke Hahn at de.wikipedia

Research into the toxin of the world's only venomous primate, the slow loris, is shedding light on the potential origins of the allergic qualities of cats.


An international team, led by University of Queensland's Associate Professor Bryan Fry, has been studying slow lorises at the Cikananga Wildlife Rescue Centre in Indonesia.

"Slow lorises are the only known primates with venom and they've been virtually unstudied," Dr. Fry said.

"Despite being a mystery to science, they're commonly smuggled from the wild and sold in the pet trade, so our rescue centre research was the perfect opportunity to do some good in a bad situation.

"Generally slow lorises use their venom to fight with other slow lorises, causing very slow-to-heal wounds.

"But, when humans are bitten, the victim will display symptoms as if they're going into allergic shock."

He said this similarity was even more striking when studied in the lab.

"We analyzed the DNA sequence of the protein in slow loris venom, discovering that it's virtually identical to the allergenic protein on cats.

"Cats secrete and coat themselves with this protein, and that's what you react to if you're allergic to them.

"Our theory is that since this protein is being used as a defensive weapon in slow lorises, it makes sense that cats may be using the allergen as a defensive weapon too.

"The fact that so many people are allergic to cats mightn't be a coincidence.

"This may have been evolutionarily selected for in the wild as a defense against predators.

"This ability to trigger allergy as a weapon mightn't be something restricted to slow lorises, but may have separately evolved in cats at the same time.

"This is a fascinating hypothesis that we are looking to test in future research."

Dr. Fry said the team regarded this as another elegant example of evolution in action.

"This finding shows how inventive nature is when developing new toxic arsenals," he said.

"The human allergy to cats is so prevalent that it would be a remarkable coincidence if this wasn't an evolved defensive weapon, like the same protein used by slow lorises.

"Your pet cat wouldn't know it, but it may have evolved a toxic defense to keep predators as far away from it as possible.

"Similarly, this line of research opens up other fascinating research areas, such as the allergies to ants and bees also being something that has been selected for by evolution—where the victim's immune system is being high-jacked.

"This study is a great example of what makes science so wonderful, where every answer spawns several new and interesting questions."

The research has been published in Toxins.


Explore furtherSlow loris study reveals human rhythm of sleep may be evolutionarily conserved
More information: undefined Scheib et al. The Toxicological Intersection between Allergen and Toxin: A Structural Comparison of the Cat Dander Allergenic Protein Fel d1 and the Slow Loris Brachial Gland Secretion Protein, Toxins (2020). DOI: 10.3390/toxins12020086
Provided by University of Queensland

What the brain really thinks about forever chemicals
by Amy Patterson Neubert, Purdue University FEBRUARY 5, 2020

Forever chemicals are considered a public health issue as adverse health effects have been shown to affect hormones and other aspects of the endocrine system, and some are potentially neurotoxic. But to what extent is unknown, especially for the years and decades they may accumulate in the brain. Credit: Stuart Briers

The human-made chemicals that make our kitchen pans stick-free, our athletic wear water-repellent and firefighting chemicals more efficient do their jobs incredibly well, but it's at the expense of lingering in the body and environment for what is believed to be forever.


These forever chemicals, perfluorooctane sulfonate and perfluorooctanoic acid, more commonly known as PFOS and PFOA, make life easier. But scientists have many questions about these synthetic compounds' long-term effects. They are being used less by consumers, and companies that once championed them are stepping away. But they still have important military and industrial applications, especially in firefighting foams. Even if production completely stopped, the world will still live with them forever.

"These chemicals are detectable in the blood of almost every human. They are often found in other species, as well, including polar bear and whale brains," said Jason Cannon, an associate professor of toxicology at Purdue University. "The carbon-fluorine bond is one of the strongest in nature, and it is difficult to break down, especially when there is more than one fluorine atom on the carbon atom. Most chemicals that we consume or absorb will leave the body in a different chemical form. To the best of our knowledge, these chemicals are not very well metabolized so they bioaccumulate."

These forever chemicals are something that Cannon refers to as a major public health issue as adverse health effects have been shown to affect hormones and other aspects of the endocrine system. Both PFOS and PFOA are per- and polyfluoroalkyl substances, more commonly known as PFAS, and are potentially neurotoxic. But to what extent is unknown, especially for the years and decades they may accumulate in the brain.

"And which regions they accumulate within the brain is unknown," said Cannon, who studies dietary toxins and neurological disease, including gene-environment interactions in Parkinson's disease.

Cannon's recent study published in Toxicological Sciences determined that PFOS is selectively neurotoxic and relevant to specific neurological diseases. In this study, roundworms were exposed to PFOS and PFAS, and it was shown that their dopamine levels and dopamine neurons were highly sensitive and declined. In mammals, dopamine is key to movement, reward and addiction.


"As a Parkinson's disease lab, seeing dopamine level depletions is a hallmark feature of the disease, but starting here, we need to be careful of our interpretation," Cannon said. "Beyond Parkinson's disease, there are a number of dopamine regions in the brain that could be affected and imply neurodegenerative issues or mental health issues. More research is needed."

Cannon's earlier research, published in Toxicology and Applied Pharmacology, took a step toward looking at how dopaminergic function may be affected. This study found that PFOS exposure led to selective decreases of dopamine levels in Northern leopard frogs, a sentinel species. Northern leopard frog larvae were used for testing because their brains feature certain chemical bio features that are more similar to those in humans than those in rodents. This frog species has a breakdown product of dopamine called neuromelanin that binds with toxins.

The three doses evaluated in a laboratory setting reflected high-level amounts from possible military site contaminations. The dopamine decreased significantly in the brains of frogs treated with PFOA at 1,000 parts per billion and PFOS at 100 and 1,000 parts per billion).

"The 1,000 is really pushing it, but the 100, well, there have been some contaminated sites that have been reported to be close to that level," he said. "This is one of the difficulties in conducting toxicology studies; you want environmentally relevant dose but you also are trying model years of exposure over a short time frame. Certainly, the highest dose is probably pretty weak for environmental relevance, but the two lower doses do bear some environmental relevance. We are conducting studies at even lower doses."

These studies on PFAS accumulation in the brain and resultant neurotoxicity were possible thanks to collaborations with labs led by Linda S. Lee, professor of agronomy, and Maria S. Sepúlveda, professor of ecology and natural systems. Cannon also is a member of Purdue's Institute for Integrative Neuroscience and the Center for the Environment, both of which are in Purdue's Discovery Park. He also is a member of the Center for Research on Brain, Behavior and NeuroRehabilitation, CEREBBRAL, in Purdue's College of Health and Human Sciences.

Although many PFOS and PFOAs have been removed, many alternatives with shorter chains are being created.

"It is thought that the shorter chain PFOAs are less toxic," Cannon said. "But I would say we truly don't know that. The data is not there. We have all these alternatives in the environment with little to no toxicity testing. In some cases that may be true. They may metabolize and leave the body faster, but from a neurological standpoint the smaller compounds usually penetrate the brain better. So that is something we need to pay attention too."

Explore furtherPersistent environmental contaminant changes the gut microbiome of mice
More information: Shreesh Raj Sammi et al. Perfluorooctane Sulfonate (PFOS) Produces Dopaminergic Neuropathology in Caenorhabditis elegans, Toxicological Sciences (2019). DOI: 10.1093/toxsci/kfz191

Rachel M. Foguth et al. Developmental exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) selectively decreases brain dopamine levels in Northern leopard frogs, Toxicology and Applied Pharmacology (2019). DOI: 10.1016/j.taap.2019.114623
Journal information: Toxicological Sciences , Toxicology and Applied Pharmacology

Mosaic X-rays reveal Peruvian mummy mysteries

by Debora Van Brenk, University of Western Ontario FEBRUARY 5, 2020

LONG READ 

Undergraduate Anthropology student Lauren Poeta prepares a mummy bundle – called a fardo – of a Peruvian child for X-rays. The Western team has developed scanning processes that better assesses the mummy without damaging the fardo. Credit: Andrew Nelson // Special to Western News

Western researchers, including two undergraduate students, have become pivotal players in developing a mobile X-ray protocol that could transform how mummies are examined in the field.

Anthropology professor Andrew Nelson and his team have pioneered a process to digitize and stitch together X-ray images so that they can non-destructively 'view' Peruvian mummy bundles in their entirety. The process will enable other anthropologists to conduct valuable work without damaging the objects.

"Lots of people have X-rayed mummies. But, as far as I know, we're the first to do the mosaic X-ray technique and do that digitally," Nelson explained.

Mummy bundles—called fardos—sometimes have been examined by unwrapping the textiles encasing the mummy. That process destroys the mummy and its context at least as much as it informs researchers about the past.

A less destructive but more time-consuming examination entails X-raying the bundles using film, which is then developed by hand, then transporting the heavy images home and analyzing them from afar.

But this new process is faster, portable and produces a far more complete picture.

Here's how it works:

Researchers bring a suitcase-sized machine—Nelson's was funded by the Social Sciences and Humanities Research Council of Canada (SSHRC) – originally designed for use by veterinarians. The X-rays then go straight to the computer in digital form. No need to process into film or transport anything off-site. Those two-dimensional images are then electronically stitched together into composite, full-body images for immediate analyses.

Undergraduate Anthropology student David Seston examines digital X-rays of mummy bundles on site in Pachacamec, Peru. Credit: Andrew Nelson // Special to Western News

That scan can stand on its own as a more-than-basic record of the mummy's condition, position and setting. It can also offer rich enough detail for researchers to decide whether the mummy warrants further study through more detailed computer tomography (CT) scanning.

Last summer, Nelson's team conducted 880 X-rays and 31 CT scans in six days at the archaeological site of Pachacamac, Peru, where almost 200 fardos were discovered during excavation for a new museum in 2015.

This is the first time these mummy bundles—which date from about AD 1100 to AD1470—have been examined.

While the X-rays showed many mummies inside the bundles were no longer intact, the scans also indicated many were worthy of further non-destructive investigation.

"The great thing about doing the X-rays digitally and on site was the instant feedback we had," said David Seston, in his final year of undergraduate Anthropology studies and a key member of the team in data management and tech troubleshooting during the six-week study.

Anthropology Ph.D. student Joanna Motley pioneered the composite work in X-ray imaging.

Credit: University of Western Ontario

Lauren Poeta, now in her fourth year of Anthropology, said the fieldwork in Peru—which included both teaching and learning from Peruvian researchers—offered an unparalleled opportunity in experiential learning.

"It was incredible because you don't expect to see that or have the opportunity to do that after just your third year. You get to do the experiential stuff. Instead of seeing pictures in two dimensions or in a textbook, this is totally different. You start to learn what to look for and what's important to see."

Poeta developed a standardized checklist of what researchers should be looking for as they try to discover how the fardos represent a microcosm of their society, including identifying the:

• Wrapping textile;
• Position of the mummy whether extended or with legs flexed towards their chest;
• Person's age, sex and any suspected health issues before death; and
• Type and location of any other artifacts buried with them.

Some fardos that have been CT-scanned and further analyzed show unusual objects wrapped with them.

Decorative shells. Stones. A mysterious folded disc they've nicknamed a 'taco." One person has a sharp object pierced through an eye socket. Another has a tattoo on one hand. One is surrounded by a 'cloud' of cotton seeds, be it to provide filler for the fardo or as a symbol for something else, no one yet knows.

An X-ray composite of a Peruvian mummy bundle showed this skull with an eye socket pierced with a sharp object. A CT scan of the skull of the same Peruvian mummy shows greater detail, including the textiles that were placed around him in death.

Another question as-yet-unanswered is whether mummification—the preservation of tissue and clothing—was the main intent for wrapping and encasing the bodies, or whether mummification was an unintended result of the process, coupled with the dry climate and their burial in sand.

Together, all these details form clues into who these people were as individuals, how they lived, how they interacted with their community and how they were respected in death. They are, Nelson said, individually and collectively important to the study of pre-Columbian life in Peru.

Further study of the fardos and their images continues here year-round and by Peruvian researchers, with further work expected by a Western-Peruvian team this coming summer. "It's the awesome part of having a multi-year project," Nelson said.

A CT scan of the skull of the same Peruvian mummy shows greater detail, including the textiles that were placed around him in death. Credit: University of Western Ontario

Meanwhile, they have co-authored six collaborative papers about their work during and since last summer's research in Peru, and have presented research at archaeological and anthropological proceedings.

For Poeta, the experiential learning offered critical-thinking skills and a greater passion for anthropological fieldwork.

Seston said the experiential learning was both a personal and professional stretch.

Researchers do a preliminary examination of a mummy bundle, one of hundreds discovered in Pachacamec, Peru, during a 2015 excavation to build a new museum. Pictured are, from left, Western student Lauren Poeta, Anthropology professor Andrew Nelson, Arizona researcher Suellen Gauld and archaeologist Sarita Fuentes Villalobos of the Site Museum at Pachacamac. Credit: University of Western Ontario

"As an undergraduate, the chances of getting this kind of opportunity are incredibly rare. I knew when we went down there that this would change my perspective—but I never expected how much.

"A lot of work I do takes place on a computer. But being actually in the field and examining them changes my perspective 100 percent. It's not just an image on a screen. These are people and you have to respect them as people. You honour them by bringing them out and bringing back their stories."

Micro-CT scans show 2,100-year-old 'hawk' mummy a stillborn baby

Ultrasound can selectively kill cancer cells

by California Institute of Technology FEBRUARY 5, 2020

LONG READ

Artist's depiction of ultrasound waves destroying a cancer cell while leaving healthy cells intact. Credit: California Institute of Technology

A new technique could offer a targeted approach to fighting cancer: low-intensity pulses of ultrasound have been shown to selectively kill cancer cells while leaving normal cells unharmed.

Ultrasound waves—sound waves with frequencies higher than humans can hear—have been used as a cancer treatment before, albeit in a broad-brush approach: high-intensity bursts of ultrasound can heat up tissue, killing cancer and normal cells in a target area. Now, scientists and engineers are exploring the use of low-intensity pulsed ultrasound (LIPUS) in an effort to create a more selective treatment.

A study describing the effectiveness of the new approach in cell models was published in Applied Physics Letters on January 7. The researchers behind the work caution that it is still preliminary—it still has not been tested in a live animal let alone in a human, and there remain several key challenges to address—but the results so far are promising.

The research began five years ago when Caltech's Michael Ortiz, Frank and Ora Lee Marble Professor of Aeronautics and Mechanical Engineering, found himself pondering whether the physical differences between cancer cells and healthy cells—things like size, cell-wall thickness, and size of the organelles within them—might affect how they vibrate when bombarded with sound waves and how the vibrations might trigger cancer cell death. "I have my moments of inspiration," Ortiz says wryly.

And so Ortiz built a mathematical model to see how cells would react to different frequencies and pulses of sound waves. Together with then-graduate student Stefanie Heyden (Ph.D. '14), who is now at ETH Zurich, Ortiz published a paper in 2016 in the Journal of the Mechanics and Physics of Solids showing that there was a gap in the so-called resonant growth rates of cancerous and healthy cells. That gap meant that a carefully tuned sound wave could, in theory, cause the cell membranes of cancerous cells to vibrate to the point that they ruptured while leaving healthy cells unharmed. Ortiz dubbed the process "oncotripsy" from the Greek oncos (for tumor) and tripsy (for breaking).

Excited by the results, Ortiz applied for and received funding to continue the research through Caltech's Rothenberg Innovation Initiative (RI2), an endowed program launched with funding from the late Caltech trustee Jim Rothenberg and his wife, Anne Rothenberg, to support research projects with high commercial potential. Ortiz also recruited doctoral student Erika F. Schibber (MS '16, Ph.D. '19), whose research involved the study of vibrations on satellites, to work on the project.

(L to R) Jian Ye and Peter P. Lee of City of Hope. Credit: Eliza Barragan, Ph.D/City of Hope

Ortiz then invited Mory Gharib (Ph.D. '83), Hans W. Liepmann Professor of Aeronautics and Bioinspired Engineering, to attend a meeting of his research group. Gharib, a prolific inventor, has shepherded numerous research developments from the lab to the market. For example, a prosthetic polymer heart valve he designed was implanted in a human for the first time in July, and he also created a smartphone app for monitoring heart health; an eye implant he designed to prevent glaucoma-related blindness has been implanted in more than 500,000 patients since 2012.

Intrigued by the project, Gharib pitched the idea to one of his advisees, David Mittelstein. As a graduate student in the MD-Ph.D. Program that is run by Caltech and the Keck School of Medicine of USC, Mittelstein was already working on the aforementioned prosthetic polymer valve with Gharib. But, in the oncotripsy project, he saw the opportunity to participate in research from its theoretical conception to its proof of concept.

"Mory and Michael really empowered me to take the lead on this project, designing and building ways to test Michael's theory in the real world," says Mittelstein, who will defend his dissertation at Caltech in mid-February before heading back to USC to complete his medical degree.

Mittelstein assembled a team to tackle the project, recruiting ultrasound expert Mikhail Shapiro, a professor of chemical engineering at Caltech. Shapiro recently devised a system that allows ultrasound to reveal gene expression in the body and has designed bacteria that reflect sound waves so that they can be tracked through the body via ultrasound.

In the Shapiro Lab, Mittelstein began subjecting hepatocellular carcinoma, a common liver cancer, to various frequencies and pulses of ultrasound, and measuring the results.

Meanwhile, Caltech trustee Eduardo A. Repetto (Ph.D. '98) introduced Ortiz to Peter P. Lee, chair of the Department of Immuno-Oncology at City of Hope, a cancer and research center in Duarte. As a physician-scientist, Lee is passionate about getting new treatments to patients. "When I heard about it, I thought it was intriguing and that, if it worked, could be a revolutionary way of treating cancer," Lee says. Other City of Hope researchers, including postdoc Jian Ye and oncologist M. Houman Fekrazad, also joined the project.

Erika F. Schibber. Credit: California Institute of Technology

With additional funding from Amgen and the Caltech–City of Hope Biomedical Research Initiative, Mittelstein built a pilot instrument at City of Hope to mirror the one at Caltech, enabling his colleagues there to test samples without having to transport them back and forth between Duarte and Pasadena. Over time, Lee and his team at City of Hope expanded the repertoire of cancer cell lines being tested, drawing samples from humans and mice to include colon and breast cancer. They also tested a variety of healthy human cells, including immune cells, to check how the treatment affects these cells.

The hope, Lee says, is that ultrasound will kill cancer cells in a specific way that will also engage the immune system and arouse it to attack any cancer cells remaining after the treatment.

"Cancer cells are quite heterogeneous, even within a single tumor," Lee explains, "so it would be almost impossible to find a range of settings for the ultrasound that could kill every single cancer cell. This would leave surviving cells that could cause a tumor to regrow."

More than 50 million cells die in your body every day. Most of those deaths occur when cells simply grow old and die naturally through a process called apoptosis. Sometimes, however, cells die as the result of infection or injury. A healthy immune system can tell the difference between apoptosis and injury, ignoring the former while rushing to the site of the latter to attack any invading pathogens.

If ultrasound can be used to cause cell death in a way that the body's immune system recognizes as injury, instead of as apoptosis, this could lead to the site of the tumor being flooded with white blood cells that could attack remaining cancer cells.

So far, all of the testing has been done in cell cultures in petri dishes, but the Caltech–City of Hope team plans to expand the testing to solid tumors and, eventually, living animals. Back in the Ortiz lab, Schibber used the results of the lab tests to refine the mathematical models, digging deeper to make sure that the researchers understand exactly how the sound waves are killing the cancer cells.

Credit: David Mittlestein

"We're learning more about how different cancer cells vibrate and sustain damage over many cycles of insonation, a process that we term 'cell fatigue,'" says Schibber, who defended her thesis on the topic in 2019 and is now a postdoctoral researcher in aerospace at Caltech. In Shapiro's lab, Mittelstein found that the formation of tiny bubbles (a process called cavitation) that could also cause some of the damage. Together, these developments are providing a conceptual basis for understanding the trends observed in the experiments.

Mittelstein hopes to stay involved in the project after his dissertation defense but, above all else, is eager to see the research continue and to one day lead to an effective cancer treatment.

"This is an exciting proof-of-concept for a new kind of cancer therapy that doesn't require the cancer to have unique molecular markers or to be located separately from healthy cells to be targeted. Instead we may be able to target cancer cells based on their unique physical properties," he says.

The Applied Physics Letters paper is titled "Selective ablation of cancer cells with low intensity pulsed ultrasound." Co-authors include Caltech undergraduate student Ankita Roychoudhury and Leyre Troyas Martinez, an undergraduate student working on a Caltech Summer Undergraduate Research Fellowship (SURF).

Ultrasound selectively damages cancer cells when tuned to correct frequencies

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More information: David R. Mittelstein et al. Selective ablation of cancer cells with low intensity pulsed ultrasound, Applied Physics Letters (2020). DOI: 10.1063/1.5128627

Origin of ambergris verified through DNA analyses

by Bob Yirka , Phys.org FEBRUARY 5, 2020 

Details for ambergris samples analysed. (a) Map showing localities where ambergris samples were originally found. (b) Photographs showing high diversity in physical characteristics of ambergris fragments: TEXEL151212 (from dissected whale specimen) was grainy in consistency, while jetsam samples superficially appeared more dense and heterogeneous, and were internally equigranular and significantly paler in colour. Credit: Biology Letters (2020). DOI: 10.1098/rsbl.2019.0819

A team of researchers from Denmark, the U.K. and Ireland has identified the origin of ambergris. In their paper published in the journal Biology Letters, the group describes analyzing DNA sequences from ambergris samples found on beaches in New Zealand and Sri Lanka, and what they learned.

Ambergris is a lump of material often found on beaches. Because of its rarity, it is extremely valuable, and dogs and even camels have been trained to use their strong senses of smell to find it. Over human history, ambergris has been valued for its musky scent. For thousands of years, people have been finding washed-up ambergris on beaches around the world. Over time, whalers began suggesting it was made by sperm whales—they had found samples of it in whale guts. But until now, it had never been proven that the whales actually created the material.

People use it in oils to scent objects such as gloves or as an anointment. But its origin has been murky. Examples of ambergris have been found in the back end of sperm whales, suggesting it might be nothing more than condensed feces. In this new effort, the researchers used DNA sequencing to test whether ambergris found on beaches is the same material as that found in sperm whales, and if so, to confirm whether it was made by the whales.

The work involved obtaining small samples from ambergris lumps found on beaches in New Zealand and Sri Lanka and conducting DNA sequencing. The researchers then compared their findings with DNA sequences from sperm whales, and found a match. The sequencing confirmed that the jetsam ambergris was genetically the same as whale ambergris, and both were created by sperm whales. But that is not the end of the story. Now that scientists know that sperm whales create ambergris, they want to know how and why it is formed, and whether it serves any useful purpose for the whales. Some have suggested in the past that if the lumps do come from whales, they are likely little more than rectal pearls, fecal matter in the rectum that builds up on a bit of indigestible material until it grows large enough to be expelled

Ambergris—how to tell if you've struck gold with 'whale vomit' or stumbled upon sewage

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More information: Ruairidh Macleod et al. DNA preserved in jetsam whale ambergris, Biology Letters (2020). DOI: 10.1098/rsbl.2019.0819