Culture

The Lancet Child & Adolescent Health: First Europe-wide study of children confirms COVID-19 predominately causes mild disease in children and fatalities are very rare

Children with COVID-19 generally experience a mild disease and fatalities are very rare, according to a study of 582 patients from across Europe published today in The Lancet Child & Adolescent Health journal.

The study, which included children and adolescents aged from 3 days up to 18 years old, found that although the majority were admitted to hospital (62%, 363/582), fewer than one in ten patients required treatment in intensive care (8%, 48/582).

The researchers note that their study only involved patients who had sought medical help and been tested for COVID-19, and so milder cases would not have been included. They advise against extrapolating the numbers observed in their study to the wider population. However, they say their findings should be taken into consideration when planning for demand on intensive care services as the pandemic progresses.

Dr Marc Tebruegge, lead author from the UCL Great Ormond Street Institute of Child Health in London, UK, said: "Our study provides the most comprehensive overview of COVID-19 in children and adolescents to date. We were reassured to observe that the case fatality rate in our cohort was very low and it is likely to be substantially lower still, given that many children with mild disease would not have been brought to medical attention and therefore not included in this study. Overall, the vast majority of children and young people experience only mild disease. Nevertheless, a notable number of children do develop severe disease and require intensive care support, and this should be accounted for when planning and prioritising healthcare resources as the pandemic progresses." [1]

The study was carried out over a 3.5 week period from 1st to 24th April 2020, during the initial peak of the European COVID-19 pandemic. It involved 82 specialist healthcare institutions across 25 European countries. All of the 582 patients included in the study were confirmed to be infected with the SARS-CoV-2 virus by a PCR test. Only a quarter (25%, 145/582) had pre-existing medical conditions. This contrasts with adult studies where the proportion of patients with co-morbidities is typically far higher, but likely reflects that children have fewer chronic medical problems than adults overall in the general population, the authors say.

The researchers found that the most common symptom reported was fever (65%, 379/582). Around half of the patients had signs of upper respiratory tract infection (54%, 313/582) and a quarter had evidence of pneumonia (25%, 143/582). Gastrointestinal symptoms were reported in around a quarter of the children (22%, 128/582), 40 of whom did not have any respiratory symptoms. Some 92 children, most of whom were tested due to close contact with a known COVID-19 case, had no symptoms at all (16%, 92/582).

The vast majority of patients did not require oxygen or any other support to help them breathe at any stage (87%, 507/582). Only 25 children needed mechanical ventilation (4%, 25/582), but when they did need it, that support was typically required for a prolonged period, often for a week or more (range 1-34 days).

The number of patients receiving antiviral or immunomodulatory therapies were too low to draw conclusions about the efficacy of any of the treatments used. The authors say robust clinical trial data are urgently needed to help doctors make decisions regarding the best treatment strategy for children under their care.

Dr Florian Götzinger, from Wilhelminenspital in Vienna, Austria, said: "Although COVID-19 affects children less severely than adults overall, our study shows that there are severe cases in all age groups. Those who have pre-existing health issues and children under one month of age were more likely to be admitted to intensive care. Well-designed, randomised controlled studies on antiviral and immunomodulatory drugs in children are needed to enable evidence-based decisions regarding treatment for children with severe COVID-19." [1]

29 children were found to be infected with one or more additional respiratory viruses at the same time as SARS-CoV-2, such as cold or flu viruses. Of these, 24% required intensive care (7/29) compared with 7% of children with no additional viruses detected, (41/553).

Dr Begoña Santiago-Garcia, one of the lead authors from University Hospital Gregorio
Marañón in Madrid, Spain, said: "This is the first study of children with COVID-19 to include data from multiple countries and multiple centres. Of note, we found that children in whom additional viruses were detected in the respiratory tract at the same time as SARS-CoV-2 were more likely to be admitted to intensive care. This could have important implications for the upcoming winter season, when cold and flu infections will be more common." [1]

Four patients died during the study period, two of whom had pre-existing medical conditions. All of the patients who died were older than 10 years of age. However, the overwhelming majority of patients were alive when the study closed (99%, 578/582) with only 25 (4%) still experiencing symptoms or needing support for their breathing.

At the time the study was conducted, testing capacity in many European countries was lower than demand, and so many children with COVID-19 and mild symptoms would not have been tested or diagnosed. Different countries were using different criteria to screen for the SARS-CoV-2 virus. Some were screening all children admitted to hospital while others were more selective in which patients were offered a test. This lack of standardisation makes it difficult to generalise the findings to the wider population, the authors say, but the true case fatality rate in children is likely substantially lower than that observed in this study (0.69%, 4/582).

Credit: 
The Lancet

Monster black hole found in the early universe

video: Astronomers have discovered the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO). It is also the first quasar to receive an indigenous Hawaiian name, Pōniuāʻena.

Image: 
International Gemini Observatory/NOIRLab/NSF/AURA/Pete Marenfeld, ESA/Hubble, NASA, M. Kornmesser. A Special Thanks to A Hua He Inoa and the 'Imiloa Astronomy Center of Hawai‘i Music: zero-project -- The Lower Dungeons (zero-project.gr).

Astronomers have discovered the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF's NOIRLab. It is also the first quasar to receive an indigenous Hawaiian name, Pōniuāʻena. The quasar contains a monster black hole, twice the mass of the black hole in the only other quasar found at the same epoch, challenging the current theories of supermassive black hole formation and growth in the early Universe.

After more than a decade of searching for the first quasars, a team of astronomers used the NOIRLab's Gemini Observatory and CTIO to discover the most massive quasar known in the early Universe -- detected from a time only 700 million years after the Big Bang [1]. Quasars are the most energetic objects in the Universe, powered by their supermassive black holes, and since their discovery astronomers have been keen to determine when they first appeared in our cosmic history.

Systematic searches for these objects have led to the discovery of the most distant quasar (J1342+0928) in 2018 and now the second most distant, J1007+2115 [2]. The A Hua He Inoa program named J1007+2115 Pōniuāʻena, meaning "unseen spinning source of creation, surrounded with brilliance" in the Hawaiian language [3]. The supermassive black hole powering Pōniuāʻena is 1.5 billion times more massive than our Sun.

"Pōniuāʻena is the most distant object known in the Universe hosting a black hole exceeding one billion solar masses" said Jinyi Yang, a Postdoctoral Research Associate at the Steward Observatory of the University of Arizona.

For a black hole of this size to form this early in the Universe, it would need to start as a 10,000 solar mass "seed" black hole about 100 million years after the Big Bang, rather than growing from a much smaller black hole formed by the collapse of a single star.

"How can the Universe produce such a massive black hole so early in its history?" wondered Xiaohui Fan, Regents' professor and associate department head of the Department of Astronomy at the University of Arizona. "This discovery presents the biggest challenge yet for the theory of black hole formation and growth in the early Universe."

Current theory suggests that at the beginning of the Universe following the Big Bang, atoms were too distant from one another to interact and form stars and galaxies. The birth of stars and galaxies as we know them happened during the Epoch of Reionization, beginning about 400 hundred million years after the Big Bang. The discovery of quasars like Pōniuāʻena, deep into the reionization epoch, is a big step towards understanding this process of reionization and the formation of early supermassive black holes and massive galaxies. Pōniuāʻena has placed new and important constraints on the evolution of the matter between galaxies (the intergalactic medium) in the reionization epoch.

The search for distant quasars began with the research team combing through large area surveys such as the DECaLS imaging survey which uses the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope, located at CTIO in Chile. The team uncovered a possible quasar in the data, and in 2019 they observed it with telescopes including the Gemini North telescope and the W. M. Keck Observatory both on Maunakea on Hawai'i Island. Gemini's GNIRS instrument confirmed the existence of Pōniuāʻena.

"Observations with Gemini were critical for obtaining high-quality near-infrared spectra which provided us with the measurement of the black hole's astounding mass," said Feige Wang, a NASA NHFP fellow at the Steward Observatory of the University of Arizona.

In honor of its discovery from Maunakea, this quasar was given the Hawaiian name Pōniuāʻena. The name was created by thirty Hawaiian immersion school teachers during a workshop led by the A Hua He Inoa group, a Hawaiian naming program led by the 'Imiloa Astronomy Center of Hawai'i. Pōniuāʻena is the first quasar to receive an indigenous name.

"In addition to the teamwork of the telescopes of NOIRLab that made this discovery possible, it is exciting to see the collaboration of science and culture in local communities, highlighted by this new name," said Chris Davis, Program Officer at the National Science Foundation.

"I am extremely grateful to be a part of this educational experience -- it is a rare learning opportunity," said Kauʻi Kaina, a High School Hawaiian Immersion Teacher from Kahuku, Oʻahu who was involved in the naming workshop. "Today it is relevant to apply these cultural values in order to further the wellbeing of the Hawaiian language beyond ordinary contexts, such as in school, but also so that the language lives throughout the Universe."

Credit: 
Association of Universities for Research in Astronomy (AURA)

MicroCT reveals detailed head morphology of arthropod, Leanchoilia illecebrosa

image: (A) YKLP11423, 5mm-long juvenile, ventral view; (B) YKLP11422, 7mm-long juvenile, ventral view.

Image: 
Javier Ortega-Hernández and Yu Liu

The Chengjiang biota in the Yunnan Province of China contains one of the most species-rich and well-preserved fossiliferous deposits for the early Cambrian (ca. 518 million years old), including numerous arthropod species. However, several Chengjiang arthropods have an unfamiliar morphology, are extremely rare, or are incompletely preserved, which often leads to many of these species being problematic, poorly known, or often both, thus hindering their contribution towards reconstructing the evolution of this major animal group.

Javier Ortega-Hernández, Assistant Professor in the Department of Organismic and Evolutionary Biology and Curator of Invertebrate Paleontology in the Museum of Comparative Zoology at Harvard University, and Yu Liu, Professor of Paleobiology, Yunnan University, China have collaborated for years in the study of Chengjiang arthropods and their evolutionary significance. Their latest paper in Current Biology shows with unprecedented clarity the head morphology of the species Leanchoilia illecebrosa - a member of Megacheira, a major extinct group characterized by distinctively raptorial great appendages. Ortega-Hernández's and Liu's reexamination of Leanchoilia demonstrates the presence of a labrum - a flap-like structure overlying the mouth opening in most modern arthropods - and offers renewed support to the hypothesis that megacheirans are distant relatives of modern chelicerates (e.g. horseshoe crabs, scorpions and spiders).

Ortega-Hernández and Liu used microCT, a technique that uses X-rays to visualize features that are not easily observable on the surface of the fossils, to study the organization of the head in small juveniles of Leanchoilia illecebrosa. With microCT they were able to understand the head in greater detail than ever before, and discover features that refute previously believed hypotheses.

"The biggest surprise came when studying structures close to the mouth," said Ortega-Hernández. "Until now, the very existence of a labrum in megacheirans, and its position relative to the mouth, have been the source of heated debate. In living arthropods the labrum is considered an important feature of the head because of its precise origin during embryonic development. The 3D data on Leanchoilia allowed us to show for the first time and with great clarity that this animal indeed had a labrum. This is a useful discovery because researchers have argued with each other whether a labrum was present or not in this and other closely related species, which has prompted very different interpretations about their evolution and affinities."

The paper is the fifth in a series of publications that represent an ongoing collaboration between the research groups led by Ortega-Hernández and Liu. This study along with others in Current Biology (v29:1, 2019), BMC Evolutionary Biology (v19, 2019, and v20, 2020), and Geological Magazine (March 27, 2020) consists of the study, and often restudy, of exceptional arthropod fossils from the early Cambrian (ca. 518 million years ago) using microCT to reveal exceptional details of the preserved anatomy that are completely inaccessible through conventional preparation tools.

"With microCT we can discern between the iron-rich fossils and the iron-depleted rock matrix to produce highly detailed and informative virtual models in 3D that reveal their affinities, ecology and evolutionary significance," said Ortega-Hernández. "Although each publication is a bit different and tells a distinct story for the early evolution of arthropods, they all follow the same overall goal and structure, and use similar techniques and methodology."

"We have several ongoing projects as part of this collaboration, including many new and exciting species, as well as re-descriptions of some old favorites," said Ortega-Hernández. "There are certainly a few pleasant surprises, and we expect that this collaboration will continue yielding high-quality morphological information for several years, as we have only started to scratch the surface." The ongoing project is partially funded by the Harvard China Fund.

Credit: 
Harvard University, Department of Organismic and Evolutionary Biology

Most massive quasar known in early universe discovered on Maunakea

image: An artist's impression of the formation of quasar Pōniuā`ena, starting with a seed black hole, 100 million years after the Big Bang.

Image: 
International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld

Maunakea, Hawai'i - Astronomers have discovered the second-most distant quasar ever found using three Maunakea Observatories in Hawai'i: W. M. Keck Observatory, the international Gemini Observatory, a Program of NSF's NOIRLab, and the University of Hawai'i-owned United Kingdom Infrared Telescope (UKIRT). It is the first quasar to receive an indigenous Hawaiian name, Pōniuā`ena, which means "unseen spinning source of creation, surrounded with brilliance" in the Hawaiian language.

Pōniuā`ena is only the second quasar yet detected at a distance calculated at a cosmological redshift greater than 7.5 and it hosts a black hole twice as large as the other quasar known in the same era. The existence of these massive black holes at such early times challenges current theories of how supermassive black holes formed and grew in the young universe.

The research has been accepted in the Astrophysical Journal Letters and is available in preprint format on arXiv.org.

Quasars are the most energetic objects in the universe powered by their supermassive black holes and since their discovery, astronomers have been keen to determine when they first appeared in our cosmic history. By systematically searching for these rare objects in wide-area sky surveys, astronomers discovered the most distant quasar (named J1342+0928) in 2018 and now the second-most distant, Pōniuā`ena (or J1007+2115, at redshift 7.515). The light seen from Pōniuā`ena traveled through space for over 13 billion years since leaving the quasar just 700 million years after the Big Bang.

Spectroscopic observations from Keck Observatory and Gemini Observatory show the supermassive black hole powering Pōniuā`ena is 1.5 billion times more massive than our Sun.

Pōniuā`ena is the most distant object known in the universe hosting a black hole exceeding one billion solar masses," said Jinyi Yang, a postdoctoral research associate at the Steward Observatory of the University of Arizona and lead author of the study.

For a black hole of this size to form this early in the universe, it would need to start as a 10,000 solar mass "seed" black hole about 100 million years after the Big Bang, rather than growing from a much smaller black hole formed by the collapse of a single star.

"How can the universe produce such a massive black hole so early in its history?" said Xiaohui Fan, Regents' professor and associate department head of the Department of Astronomy at the University of Arizona. "This discovery presents the biggest challenge yet for the theory of black hole formation and growth in the early universe."

Current theory holds the birth of stars and galaxies as we know them started during the Epoch of Reionization, beginning about 400 million years after the Big Bang. The growth of the first giant black holes is thought to have occurred during that same era in the universe's history.

The discovery of quasars like Pōniuā`ena, deep into the reionization epoch, is a big step towards understanding this process of reionization and the formation of early supermassive black holes and massive galaxies. Pōniuā`ena has placed new and important constraints on the evolution of the matter between galaxies (intergalactic medium) in the reionization epoch.

"Pōniuā`ena acts like a cosmic lighthouse. As its light travels the long journey towards Earth, its spectrum is altered by diffuse gas in the intergalactic medium which allowed us to pinpoint when the Epoch of Reionization occurred," said co-author Joseph Hennawi, a professor in the Department of Physics at the University of California, Santa Barbara.

METHODOLOGY

Yang's team first detected Pōniuā`ena as a possible quasar after combing through large area surveys such as the UKIRT Hemisphere Survey and data from the University of Hawai'i Institute for Astronomy's Pan-STARRS1 telescope on the Island of Maui.

In 2019, the researchers observed the object using Gemini Observatory's GNIRS instrument as well as Keck Observatory's Near Infrared Echellette Spectrograph (NIRES) to confirm the existence of Pōniuā`ena.

"The preliminary data from Gemini suggested this was likely to be an important discovery. Our team had observing time scheduled at Keck just a few weeks later, perfectly timed to observe the new quasar using Keck's NIRES spectrograph in order to confirm its extremely high redshift and measure the mass of its black hole," said co-author Aaron Barth, a professor in the Department of Physics and Astronomy at the University of California, Irvine.

In honor of its discovery from atop Maunakea, 30 Hawaiian immersion school teachers named the quasar Pōniuā`ena through the 'Imiloa Astronomy Center of Hawai'i's A Hua He Inoa program led by renowned Hawaiian language expert Dr. Larry Kimura.

"We recognize there are different ways of knowing the universe," said John O'Meara, chief scientist at Keck Observatory. "Pōniuā`ena is a wonderful example of interconnectedness between science and culture, with shared appreciation for how different knowledge systems enrich each other."

"I am extremely grateful to be a part of this educational experience - it is a rare learning opportunity," said Kau'i Kaina, a high school Hawaiian immersion teacher from Kahuku, O'ahu who was involved in the naming workshop. "Today it is relevant to apply these cultural values in order to further the well-being of the Hawaiian language beyond ordinary contexts such as in school, but also to ensure the language lives throughout the universe."

ABOUT NIRES

The Near Infrared Echellette Spectrograph (NIRES) is a prism cross-dispersed near-infrared spectrograph built at the California Institute of Technology by a team led by Chief Instrument Scientist Keith Matthews and Prof. Tom Soifer. Commissioned in 2018, NIRES covers a large wavelength range at moderate spectral resolution for use on the Keck II telescope and observes extremely faint red objects found with the Spitzer and WISE infrared space telescopes, as well as brown dwarfs, high-redshift galaxies, and quasars. Support for this technology was generously provided by the Mt. Cuba Astronomical Foundation.

ABOUT W. M. KECK OBSERVATORY

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical/infrared telescopes on the summit of Maunakea on the Island of Hawai'i feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems.

Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

For more information, visit http://www.keckobservatory.org.

Credit: 
W. M. Keck Observatory

Hubble watches the "flapping" of cosmic bat shadow

video: This video showcases the "flapping" motion of the shadow of the star HBC 672 that has been observed by a team of researchers using the NASA/ESA Hubble Space Telescope.

The star is believed to be surrounded by a warped, saddle-shaped disc with two peaks and two dips. A planet embedded in the disc, inclined to the disc's plane, may be causing this warping. As the disc rotates around the young star, it blocks the light from that star and casts a varying, "flapping" shadow on a distant cloud.

Image: 
ESA/Hubble, K. Pontoppidan, L. Calçada, M. Kornmesser Music: Konstantino Polizois

The young star HBC 672 is known by its nickname of Bat Shadow because of its wing-like shadow feature. The NASA/ESA Hubble Space Telescope has now observed a curious "flapping" motion in the shadow of the star's disc for the first time. The star resides in a stellar nursery called the Serpens Nebula, about 1300 light-years away.

The Hubble Space Telescope captured a striking observation of the fledgling star's unseen, planet-forming disc in 2018. This disc casts a huge shadow across a more distant cloud in a star-forming region -- like a fly wandering into the beam of a flashlight shining on a wall.

Now, astronomers have serendipitously observed the Bat Shadow's "flapping". This may have been caused by a planet pulling on the disc and warping it. "You have a star that is surrounded by a disc, and the disc is not like Saturn's rings -- it's not flat. It's puffed up. And so that means that the light from the star, if it goes straight up, can continue straight up -- it's not blocked by anything. But if it tries to go along the plane of the disc, it doesn't get out, and it casts a shadow," explained lead author Klaus Pontoppidan, an astronomer at the Space Telescope Science Institute (STScI) in Baltimore, USA, whose team have published these results [1].

This "flapping" finding was also a surprise. Pontoppidan and his team observed the shadow in several filters over a period of 13 months. When they combined the old and new images, the shadow appeared to have moved.

The shadow is so large -- about 200 times the diameter of our Solar System -- that light doesn't travel instantaneously across it. In fact, it takes about 45 days for the light to travel from the star out to the best defined edge of the shadow.

Pontoppidan and his team calculate that a planet warping the disc would orbit its star in no fewer than 180 days. They estimate that it would be about the same distance from its star as Earth is from the Sun. Pontoppidan's team also suggest the disc must be flared, with an angle that increases with distance -- like a trumpet. This shape of its two peaks and two dips would explain the "flapping" of the shadow. The team also speculates that a planet is embedded in the disc, inclined to the disc's plane. If it's not a planet, a less likely explanation is a lower-mass stellar companion orbiting HBC 672 outside the plane of the disc. Pontoppidan and his team doubt this is the case, based on the thickness of the disc. There is also no current evidence for a binary companion).

The disc is a circling structure of gas, dust, and rock, and is too small and too distant to be seen, even by Hubble. However, based on the projected shadow, scientists do know that its height-to-radius ratio is 1:5.

Credit: 
ESA/Hubble Information Centre

Helping consumers in a crisis

A new study shows that the central bank tool known as quantitative easing helped consumers substantially during the last big economic downturn -- a finding with clear relevance for today's pandemic-hit economy.

More specifically, the study finds that one particular form of quantitative easing -- in which the U.S. Federal Reserve purchased massive amounts of mortgage-backed securities -- drove down mortgage interest rates, allowed consumers to refinance their house loans and spend more on everyday items, and in turn bolstered the economy.

"Quantitative easing has a really big effect, but it does matter who it targets," says Christopher Palmer, an MIT economist and co-author of a recently published paper detailing the results of the study.

All told, the study finds, the Fed's so-called QE1 phase from late November 2008 through March 2010, a part of the larger quantitative easing program, generated about $600 billion in mortgage refinancing at lower interest rates, bringing about $76 billion worth of additional spending back into the broader economy.

However, as the study also demonstrates, the people benefitting from QE1 were a relatively circumscribed group of mortgage holders: borrowers from the Government Sponsored Entities (GSEs) Fannie Mae and Freddie Mac. So while observers may talk about quantitative easing as a "helicopter drop" of money, scattered across the public, the Fed's previous interventions were relatively targeted. Recognizing that fact could shape policy decisions in the future.

"It's not like the Fed drops money from a helicopter and then it lands randomly and uniformly and equally across the population, and people pick up those dollars and spend money and are off to the races," Palmer says. "The Fed intervenes in specific ways, and specific people benefit."

The paper, "How Quantitative Easing Works: Evidence on the Refinancing Channel," is published in the latest issue of the Review of Economic Studies. The authors are Marco Di Maggio, an associate professor at Harvard Business School; Amir Kermani, an associate professor at the Haas School of Business at the University of California at Berkeley; and Palmer, the Albert and Jeanne Clear Career Development Assistant Professor at the MIT Sloan School of Management.

Mortgage relief for some

The introduction of quantitative easing during the Great Recession was a notable expansion of the tools used by central banks. Rather than limiting its holdings to treasury securities, the U.S. Federal Reserve's purchase of mortgage-backed securities -- bonds backed by home loans -- gave it more scope to boost the economy, by lowering interest rates in another area of the bond market.

The first round of quantitative easing, QE1, which began in November 2008, included $1.25 trillion in mortgage purchases. The second round, QE2, which started in September 2010, focused exclusively on treasury securities. The third round, QE3, was initiated in September 2012 and was a combination of mortgage and treasury security purchases.

To conduct the study, the researchers drew heavily on a database from Equifax, the giant consumer credit reporting agency, which includes detailed individual-level information about mortgages. That includes the size of individual loans, their interest rates, and other liabilities. The database covered about 65 percent of the mortgage market.

"It basically allowed us to trace the flow of Fed mortgage purchases down to individual households -- we could see who was refinancing when the Fed was intervening to make interest rates lower," Palmer says.

The study found that refinancing activity increased by about 170 percent during QE1, with interest rates dropping from about 6.5 percent to 5 percent. However, the Fed purchasing activity was highly focused on "conforming" mortgages -- those fitting the guidelines of the GSEs, which often mandate having loans cover no more than 80 percent of a home's value.

With the Fed not aiming its resources at nonconforming mortgages, much less refinancing occurred from people with those kinds of home loans.

"We saw a really big difference in who seemed like they were getting credit during quantitative easing," Palmer says.

That means QE1 bypassed many people who needed it the most. Consumers with nonconforming mortgages, on aggregate, were in worse financial straits than people who could put more equity into their homes initially.

Checking the data geographically, the researchers also found that much less refinancing occurred in the "sand states" where a huge number of subprime, nonconforming mortgages were issued -- especially Florida, Arizona, Nevada, and the Inland Empire region of California.

"People who are outside the conforming mortgage system are often those who need help the most, whether that's because their loan size is too big, or their equity is too small, or their credit score is too low," Palmer says. "They often needed the stimulus most and yet couldn't get it because credit was too tight."

Take it easy

Given both the success and targeted nature of QE1, Palmer suggests that future interventions could be broadened.

"One of our takeaways is that if the Fannie and Freddie requirements can be temporarily loosened, then Federal reserve QE purchases can do a lot more good, because they can reach more borrowers," Palmer says.

More broadly, surveying the economic landscape as the Covid-19 pandemic continues, Palmer says we should continue to examine how central banks can provide relief, and to whom. With interest rates very low, the U.S. Federal Reserve cannot offer much broad relief by adjusting rates. More help may come from efforts like the Main Street Lending Program facilitated by the CARES Act, which runs through September.

"When credit markets get locked up, there's less opportunity for your local restaurant or auto-body garage or toy store to take advantage of the fact that the interest rates are lower," Palmer says. Instead, targeted programs are "really an attempt to focus the monetary stimulus directly from the Fed to the people who need it."

To be sure, consumers gaining credit relief may not be as willing to spend right now as they were in 2008 or 2010. But given the economic struggles of 2020, freeing up any additional spending would be productive, Palmer says.

"If people can refinance right now, they're probably not going on shopping sprees," he says. "But there is still a lot of consumption happening that is very valuable."

Credit: 
Massachusetts Institute of Technology

University of Minnesota Medical School finds promising treatment to slow kidney disease doesn't prove out in clinical trial

MINNEAPOLIS, MN- June 25, 2020 – Historically, half or more of people with type 1 diabetes develop kidney disease, which frequently progresses to kidney failure, requiring dialysis treatment or kidney transplantation for survival, according to a study in Diabetes Care. Development and progression of kidney disease in type 1 diabetes is associated with higher levels of a chemical in the blood called uric acid. A new study from the University of Minnesota Medical School found that allopurinol, an inexpensive generic drug that reduces uric acid levels, did not show benefits in protecting from loss of filtering function in the kidney. The findings were recently published in the New England Journal of Medicine

Previous studies suggested that allopurinol may be a promising treatment to slow kidney function, but the smaller size of the studies indicated the need for a more definitive, large-scale trial to answer this important question. 

Michael Mauer, MD, professor in the Departments of Pediatrics and Medicine and kidney specialist at the University of Minnesota Medical School, and his colleagues conducted an international, multi-institution, randomized clinical trial that enrolled 530 participants to study whether allopurinol would slow the disease. The study participants had type 1 diabetes and early to moderate loss of the kidney’s filtering function.

Mauer is the co-principal investigator of the study called, Preventing Early Renal Loss in Diabetes (PERL), along with his colleague, Alessandro Doria, MD, PhD, MPH, senior investigator in Joslin Diabetes Center’s Section on Genetics and Epidemiology and professor of Medicine at Harvard Medical School. Mauer has conducted studies of diabetic kidney disease for more than 40 years and has published extensively in this field.

The PERL consortium consisted of 16 sites each led by excellent clinical scientists. Participants in the three-year, placebo-controlled and double-blinded trial received the current standard of care, including a renin-angiotensin system inhibitor—an existing type of drug shown in the 1990s to slow kidney damage, albeit incompletely. 

The key outcome measurement of kidney function for PERL was glomerular filtration rate (GFR), a measure of how much blood is filtered every minute by the kidneys. GFR drops as kidney disease progresses, and when very low, requires dialysis or kidney transplantation for survival. Over the three years of the study, levels of uric acid was decreased, on average, by about 35% among people given allopurinol compared to those who were not. Despite the reduction in uric acid levels, the study showed there was no effect on GFR.

“PERL was a textbook example of using basic science, epidemiology findings and preliminary pilot studies to identify a treatment target, and then to design a study to answer an important question,” Mauer said. “In this case, we didn’t get the result we were hoping for, but we got a clear answer to an important scientific question.”

This research was supported  by the National Institute of Diabetes and Digestive and Kidney Diseases and the Juvenile Diabetes Research Fund. 

University of Minnesota co-investigators included Luiza Maria Caramori, MD, PhD, the U of M PERL site director; William Robiner, PhD, the PERL study psychologist, and Amy Karger, MD, PhD, the PERL laboratory director. 

Other co-investigators included Andrzej Galecki, Cathie Spino, Chunyi Wu and Rodica Pop-Busi, University of Michigan; Allison Goldfine and Sylvia Rosas, Joslin Clinic; David Cherney and Bruce Perkins, University of Toronto; Ildiko Lingvay, University of Texas Southwestern Medical School; Afshin Parsa, NIH; Peter Rossing, University of Copenhagen; Ronald Sigal, University of Calgary; Maryam Afkarian, University of California at Davis; Ronnie Aronson of LMC Diabetes & Endocrinology, Toronto; Jill Crandall, Albert Einstein College of Medicine; Ian de Boer and Irl Hirsch, University of Washington; Katherine Tuttle, University of Washington; Thomas Elliott of BCDiabetes, Vancouver; Jeehea Haw and Guillermo Umpierrez, Emory University; David Maahs and Sarit Polsky, University of Colorado; Janet McGill, Washington University; Mark Molitch and Amisha Wallia, Northwestern University; Marlon Pragnell, JDRF; Peter Senior, University of Alberta; and Ruth Weinstock, SUNY Upstate Medical University.

Credit: 
University of Minnesota Medical School

Study reveals key finding about microbiome of anticancer compound-producing marine invertebrate

image: Synoicum adareanum: The Antarctic sea squirt, Synoicum adareanum at 80' (24 meters) lives amongst the red algae, bryozoans and starfish on the seafloor. It is a non-motile benthic species that gets its nutrition from microorganisms and organic carbon in the seawater. Its microbiome hosts a suite of different microorganisms that can provide defenses against predation and infection in some cases. Tissues of this animal were found to contain high levels of a compound that is active against melanoma, which is thought to be produced by a member of the sea squirt's microbiome.

Image: 
Bill Baker, USF

Could the cure for melanoma - the most dangerous type of skin cancer - be a compound derived from a marine invertebrate that lives at the bottom of the ocean? A group of scientists led by Alison Murray, Ph.D. of the Desert Research Institute (DRI) in Reno think so, and are looking to the microbiome of an Antarctic ascidian called Synoicum adareanum to better understand the possibilities for development of a melanoma-specific drug.

Ascidians, or "sea squirts", are primitive, sac-like marine animals that live attached to ocean-bottoms around the world, and feed on plankton by filtering seawater. S. adareanum, which grows in small colonies in the waters surrounding Antarctica, is known to contain a bioactive compound called "Palmerolide A" with promising anti-melanoma properties - and researchers believe that the compound is produced by bacteria that are naturally associated with S. adareanum.

In a new paper published this month in the journal Marine Drugs, Murray and collaborators from the University of South Florida, the Los Alamos National Laboratory, and the Université de Nantes, France, present important new findings measuring palmerolide levels across samples collected from Antarctica's Anvers Island Archipelago and characterizing the community of bacteria that make up the microbiome of S. adareanum.

"Our longer-term goal is to figure out which of the many bacteria within this species is producing palmerolide, but to do this, there is a lot we need to learn about the microbiome of S. adareanum," Murray said. "Our new study describes many advances that we have made toward that goal over the last few years."

In 2008, Murray worked with Bill Baker, Ph.D., of the University of South Florida, and DRI postdoctoral researcher Christian Riesenfeld, Ph.D., to publish a study on the microbial diversity of one individual S. adareanum. Their new study builds upon this research by characterizing the microbial diversity of 63 different individuals that were collected from around Anvers Island.

Their results identify a what the researchers call the "core microbiome" of the species - a common suite of 21 bacterial taxa that were present in more than 80 percent of samples, and six bacterial taxa that were present in all 63 samples.

"It is a key "first" for Antarctic science to have been able to find and identify this core microbiome in a fairly large regional study of these organisms," Murray said. "This is information that we need to get to the next step of identifying the producer of palmerolide."

Another "first" for Antarctic science, and for the study of natural products in nature in general, was a comparison of palmerolide levels across all 63 samples that showed the compound was present in every specimen at high (milligram per gram specimen tissue) levels, but the researchers found no trends between sites, samples, or microbiome bacteria. Additional analysis looking at the co-occurrence relationships of the taxa across the large data set showed some of the ways that bacteria are interacting with each other and with the host species in this marine ecosystem.

"The microbiome itself is unique in composition from other ascidians, and seems to be pretty interesting, with a lot of interaction," Murray said. "Our study has opened the doors to understand the ecology of this system."

From the assemblage of bacteria that the researchers have identified as making up the core microbiome of S. adareanum, they next hope to use a genomics approach to finally be able to identify which of the bacteria are producing palmerolide - an important and needed advancement toward the development of a melanoma treatment.

"It would be a really big deal to use this compound to develop a drug for fighting melanoma, because there are just so few drugs at the moment that can be used to treat it," Murray said. "If we can identify the bacteria that produce this chemical, and with its genome understand how to cultivate it in a laboratory setting, this would enable us to provide a sustainable supply of palmerolide that would not rely on harvesting wild populations of this species in Antarctica."

Credit: 
Desert Research Institute

Scientists devise new 'bar code' method to identify critical cell types in the brain

image: Two molecular markers, indicated by the red and green fluorescence, are found together only in synaptic Schwann cells. Together they offer a "bar code" that identifies Schwann cells, an important subtype of glia.

Image: 
Valdez Lab / Center for Translational Neuroscience / Brown University

PROVIDENCE, R.I. [Brown University] -- While the brain is composed of two types of cells, glia tend to receive far less attention for their importance in brain function and disease than the more celebrated neurons. But scientists have known for more than a century that special types of glial cells are integral components of neuromuscular junctions or synapses -- points of contact between neurons and muscles that permit the brain to control movement.

Despite the significance of glial cells for the proper formation, maintenance and repair of synapses throughout the nervous system, the inability to distinguish specific glial cells at synapses from the diverse overall population of glial cells has been a major challenge in promoting and restoring the normal function of the nervous system following injuries, diseases and in old age.

A new discovery, detailed in a June 25 study in the journal eLife, may change that.

A team led by Gregorio Valdez, an associate professor of molecular biology, cell biology and biochemistry at Brown University, has identified important molecules to study and to manipulate the specific glial cells integral to synapses.

"This discovery will serve as a springboard to addressing fundamental questions and developing assays to speed the discovery of therapeutics intended to preserve and restore the normal function of neuronal circuits," said Valdez, who is affiliated with the new Center for Translational Neuroscience, established by the Carney Institute for Brain Science at Brown and the Brown Institute for Translational Science.

The study reveals that an important subtype of glia, known as Schwann cells and located at neuromuscular synapses, are the only cells in muscles expressing two specific molecules. These molecular markers provide a highly specific glial "bar code," Valdez says, that identifies the vital cell subtype.

"What this means is that we can finally figure out how all three cellular constituents of the synapse -- neurons, muscle and glia -- talk to each," Valdez said. "We now have a unique and important tool for identifying this critical component of the synapse. This is essential for knowing when and where to target to ensure synapses function appropriately."

Valdez says the novel bar code tool will pave the way for future studies, including on neuromuscular disease such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Scientists can use the molecular markers to probe the role of synaptic glia in neuromuscular synapse repair following injury, degeneration during normal aging and the progression of neuromuscular diseases.

He also anticipates that a similar approach will reveal the synaptic glial cells located at synapses between pairs of neurons in the brain.

"While our primary focus was the neuromuscular synapse, we also gathered initial evidence indicating that synaptic glia cells in the brain can be labeled and targeted using the same approach," he said. "If true, this discovery could be of immense consequence for treating a myriad of brain conditions, including those involving cognitive decline due to normal aging and Alzheimer's Disease."

Credit: 
Brown University

Smile! Photos converted into 3D from any mobile device

image: Representative image for "One Shot 3D Photography"

Image: 
Facebook

CHICAGO--It's not an exaggeration -- many of us have seemingly turned into skilled photographers overnight. With the rapid advances in handheld devices and easy-to-use photo-editing applications, people have been accustomed to snapping their own photos from their phones or tablets for years now. Some of us also are getting savvier and more creative with how photos are shared or posted.

In this new work from Facebook researchers, users are now able to turn the photos they take on their devices into 3D images within seconds. The team will demonstrate their innovative end-to-end system for creating and viewing 3D photos at SIGGRAPH 2020. The conference, which will take place virtually this year starting 17 August, gathers a diverse network of professionals who approach computer graphics and interactive techniques from different perspectives. SIGGRAPH continues to serve as the industry's premier venue for showcasing forward-thinking ideas and research.

The 2D-to-3D photo technique has been available as a "photos feature" on Facebook since late 2018. To take advantage of this feature, originally Facebook users were required to capture
photos with a phone equipped with a dual-lens camera. Now, the Facebook team has added an algorithm that automates depth estimation from the 2D input image, and the technique can be utilized directly on any mobile device, expanding the method beyond just the Facebook app and without the requirement of having a dual-lens camera.

"Over the last century, photography has gone through several tech 'upgrades' that increased the level of immersion. Initially, all photos were black and white and grainy, then came color photography, and then digital photography brought us higher quality and better-resolution images," Johannes Kopf, lead author of the work and research scientist at Facebook, says. "Finally, these days we have 3D photography, which makes photos feel a lot more alive and real."

The new framework provides users with a more practical approach to 3D photography, addressing several design objectives. Users can access the new technology via their own mobile device; the real-time conversion from a 2D input image to 3D is seamless, requiring no sophisticated photographic skills by the user and only takes a few seconds to process; and the method is robust enough to work on almost any photo -- new or one previously taken.

To refine the new system, the researchers trained a convolutional neural network (CNN) on millions of pairs of public 3D images and their accompanying depth maps and leveraged mobile-optimization techniques developed by Facebook AI. The framework also incorporates texture inpainting and geometry capture of the 2D input image to convert it into 3D, resulting in images that are more active and lively. Each automated step that converts a user's 2D photo, directly from their mobile device, is optimized to run on a variety of makes and models and is able to work with a device's limited memory and data-transfer capabilities. The best part? Users get instant gratification, as the 3D results are literally generated in a matter of seconds.

Researchers at Facebook have been working toward new and inventive ways to create high quality, immersive 3D experiences, pushing the envelope in computer vision, graphics, and machine learning. In future work, the team is investigating machine-learning methods that enable high-quality depth estimation for videos taken with mobile devices.

Credit: 
Association for Computing Machinery

Research shows COVID-19 is an independent risk factor for acute ischemic stroke

image: Puneet Belani, MD, Assistant Professor, Radiology and Neurosurgery, Icahn School of Medicine at Mount Sinai

Image: 
Mount Sinai Health System

Journal Name: American Journal of Neuroradiology: http://www.ajnr.org/content/ajnr/early/2020/06/25/ajnr.A6650.full.pdf

Title of the Article: COVID-19 is an independent risk factor for acute ischemic stroke.

Corresponding Author: Puneet Belani, MD, Assistant Professor at Icahn School of Medicine at Mount Sinai Hospital, Department of Radiology, Neuroradiology.

Bottom Line: COVID-19 infection is significantly associated with strokes, and patients with COVID-19 should undergo more aggressive monitoring for stroke.

Results: After adjusting for age, gender, and risk factors, COVID-19 infection had a significant independent association with acute ischemic stroke compared to control subjects (OR 3.9; 95% CI 1.7-8.9; p=0.001).

Why the Research Is Interesting: The first major peer reviewed study to show that COVID-19 infection is a risk factor for acute strokes.

Who: Patients presenting to New York City hospital for suspicion of stroke during COVID-19 pandemic

When: March to April 2020 during COVID-19 pandemic

What: First major peer reviewed paper showing COVID-19 can cause strokes

How: Retrospective case-control study with 123 patients presenting to the hospital for suspicion of stroke. Comparing the group of patients with stroke versus non-stroke, we showed significantly elevated number of patients with COVID-19 infection among the stroke group after stratifying for other known common stroke risk factors.

Study Conclusions: This is the first major peer reviewed study to establish a link between SARS-CoV-2 infection and increased stroke risk when accounting for confounding risk factors. Patients with COVID-19 should be evaluated early for acute neurological changes and timely workup should be performed in patients suspected to have stroke to reduce morbidity and mortality.

Said Mount Sinai's Dr. Puneet Belani of the research:
"This is the first major peer reviewed study to show that COVID-19 infection is a risk factor for acute strokes. In a study of 123 patients presenting to our New York City Hospital System for suspicion of stroke during the COVID-19 pandemic from March to April 2020, we showed that COVID-19 infection is significantly associated with strokes. Patients with COVID-19 should be evaluated early for acute neurological changes and timely workup should be performed in patients suspected to have stroke to reduce morbidity and mortality."

Credit: 
The Mount Sinai Hospital / Mount Sinai School of Medicine

COVID-19 news from Annals of Internal Medicine

Below please find a summary and link(s) of new coronavirus-related content published today in Annals of Internal Medicine. The summary below is not intended to substitute for the full article as a source of information. A collection of coronavirus-related content is free to the public at http://go.annals.org/coronavirus.

A Dangerous Myth: Does Speaking Imply Breathing?
@bidmchealth
#thisisourlanetoo

The belief that a person's ability to speak precludes the possibility of suffocation is false and can have fatal consequences. A commentary from Beth Israel Deaconess Medical Center reviews basic respiratory physiology and highlights the clinician's role in educating the public against relying on speech as a sign of adequate respiration, especially when this misconception is used to propagate injustice or violence. The authors explain that air hunger is the most uncomfortable and emotionally distressing quality of dyspnea. Data from studies of war and torture victims show that the sensation of suffocation is the single strongest predictor of posttraumatic stress disorder and can cause more persistent psychological damage than mock execution with a pistol. This finding suggests that clinicians have a fundamental responsibility to serve as advocates for persons who report respiratory distress. Read the full text: https://www.acpjournals.org/doi/10.7326/M20-4186.

Media contacts: A PDF for this article is not yet available. Please click the link to read full text. The lead author, Anica C. Law, MD, MS, can be reached through Jackie Mitchel at jsmitche@bidmc.harvard.edu.

Credit: 
American College of Physicians

Researchers discover critical new allergy pathway

Researchers at Johns Hopkins Bloomberg School of Public Health have identified the sequence of molecular events by which tiny, tick-like creatures called house dust mites trigger asthma and allergic rhinitis.

The researchers, whose study was published online June 22 in Nature Immunology, found that allergy-triggering molecules from dust mites can interact with an immune protein called SAA1, which is better known as a sentinel against bacteria and other infectious agents. The researchers showed step-by-step how this interaction between mite-molecules and SAA1 triggers an allergic-type immune response in mice.

The findings reveal what may be a significant new pathway by which allergic and inflammatory disorders arise. They also suggest that blocking the pathway could potentially work as a preventive or treatment strategy against asthma and other allergic reactions.

"We think that the signaling interactions that occur immediately downstream of the mite-proteins' activation of SAA1 may be good targets for future drugs," says study senior author Marsha Wills-Karp, PhD, the Anna M. Baetjer Professor of Environmental Health and Chair of the Department of Environmental Health and Engineering at the Bloomberg School.

Asthma affects between 8 to 15 percent of people in the U.S., and is typically triggered by dust mites, tree and grass pollens, and other allergens. Researchers suspect that this inappropriate immune triggering happens when the immune system mistakes allergens--which are otherwise harmless--for pieces of bacteria or other infectious agents. However, the molecular mechanisms underlying this misidentification haven't been well understood.

In their study, Wills-Karp and her colleagues zeroed in on SAA1, an immune protein that is found, among other places, in the fluid that lines the airways and other mucosal surfaces. A member of the evolutionarily ancient "innate immune system" of mammals, SAA1 is thought to have evolved as a sentinel or early-responder molecule that, for example, recognizes and helps clear away certain types of bacteria and other infectious agents.

The researchers found that exposure to dust-mite proteins causes an asthma-like sensitization of the airways of the control group mice. In contrast, exposure to dust-mite proteins hardly had any effect in mice in which SAA1 was neutralized by antibodies, or in mice whose genes for SAA1 were knocked out. Further experiments confirmed that SAA1, when it is present, directly binds certain dust-mite allergens called fatty-acid binding proteins, which have structural similarities with proteins found in some bacteria and parasites. This allergen-SAA1 interaction releases SAA1 into its active form, wherein it activates a receptor called FPR2 on airway-lining cells. The airway cells then produce and secrete large quantities of interleukin-33, a protein known for its ability to stimulate allergic-type immune responses.

Confirming the likely relevance to humans, the researchers found evidence of increased production of SAA1 and FPR2 in nasal airway-lining cells from patients with chronic sinusitis--which is often linked to dust-mite allergens--compared to healthy controls.

"We think that different allergens take different routes to the activation of interleukin-33 and related allergic responses, and this SAA1-FPR2 route seems to be one that is taken by some dust-mite allergens," Wills-Karp says.

She and her colleagues now plan to investigate why some people develop allergic disorders in which this pathway is hyperactive, while most don't. They also plan to explore the possibility of blocking this pathway, perhaps at the SAA1-FPR2 interaction, as a way of treating asthma and other allergic disorders.

The researchers suspect that the newly described SAA1-FPR2 allergic pathway may be relevant not only in asthma and hay fever-type disorders but also in atopic dermatitis (eczema) and food allergies--possibly even in chronic inflammatory disorders such as rheumatoid arthritis and atherosclerosis.

Credit: 
Johns Hopkins Bloomberg School of Public Health

Looking for better customer engagement value? Be more strategic on social media

image: Social Media

Image: 
Thomas Ulrich/ Pixabay.com

The more interactions and connections firm's social media marketing strategy generates, the more customer engagement value it brings.

In the new study, Fang Fang Li and Jorma Larimo from the University of Vaasa and Leonidas Leonidou from the University of Cyprus look at the strategic use of social media from firm perspective, and systematically consolidate and extend present knowledge on social media marketing strategies.

The study was recently published in one of the world's leading journals in marketing field - Journal of the Academy of Marketing Science (ABS 4*).

- Despite widespread understanding among marketers of the need to integrate social media into firms' marketing strategies, relatively few firms have strategized their social media appearance and involvement. For most companies, the ongoing challenge is not to initiate social media campaigns, but to effectively and strategically use social media in order to engage customers and build valuable relationships with them, say professor Jorma Larimo and doctoral student Fang Fang Li from the University of Vaasa.

To gain insights from both academics and practitioners, the authors interviewed 15 decision makers from China, Finland and Sweden and conducted two separate surveys, first participated by 52 marketing managers from USA and the second one received inputs from 43 social media marketing international scholars.

The study shows that the mere use of social media alone does not generate customer value, but rather, the connections and interactions between the firm and its customers - as well as among customers themselves - can be used strategically for resource transformation and exchanges between the interacting parties.

- Interacting with customers via social media provides tremendous opportunities for firms to learn more about their customers and opens up new possibilities for product or service co-creation, says Fang Fang Li.

Another key result is that the in the study four distinctive social media marketing strategies were identified, namely social commerce strategy, social content strategy, social monitoring strategy, and social CRM strategy, representing progressing levels of strategic maturity in social media use. Their adoption does not follow a sequential pattern, but is highly depended on the firm´s ability to identify and leverage customer-owned resources, as well as firm´s willingness to allocate resources in order to foster collaborative conversations, develop appropriate responses, and enhance customer relationships.

- Actively interacting with customers using social media should be a never-ending process, which, with proper monitoring and right incentives, can help favorably influence customer behavior, says professor Jorma Larimo.

The results offer fresh insights into the nature, conceptualization, and types of social media marketing strategies. Furthermore, the findings have important implications for social media marketing scholars and practitioners in identifying social media resources and capabilities. Authors also present several fruitful future research directions.

Credit: 
University of Vaasa

Airborne chemicals could become less hazardous, thanks to a missing math formula

image: Purdue researchers have figured out a way to calculate surface viscosity just by looking at a stretched droplet as it starts to break.

Image: 
Purdue University images/Brayden Wagoner and Osman Basaran

WEST LAFAYETTE, Ind. -- Drones and other aircraft effectively spray pesticides over miles of crops, but the method also can pollute the environment if wind carries the mist off-target.

One of the problems is that tiny droplets are hard for aerial crop sprayers, inkjet printers and a wide range of other machines to control. Purdue University engineers are the first to come up with the math formula that was missing to measure a key property of these droplets.

"There are many properties that affect how a droplet forms. One of those important properties is surface viscosity, which people have had a heck of a time trying to measure because they just didn't have the tools to do it," said Osman Basaran, Purdue's Burton and Kathryn Gedge Professor of Chemical Engineering.

Pesticides and other chemicals contain additives called surfactants. These surfactant molecules resist each other at a liquid's surface, giving rise to a sticky force called surface viscosity that can make the droplet smaller. The higher the surface viscosity, the more compact a droplet's shape.

Basaran and his students have figured out a way to calculate surface viscosity just by looking at how a droplet stretches. A picture taken of the stretched droplet as it starts to break gives the values to put into a simple math formula that provides the surface viscosity measurement.

The formula is described in a paper published in the journal Physical Review Letters. The discovery ends a decades-long race by researchers around the world to make surface viscosity measurable. Other co-authors on this paper include Hansol Wee, Brayden Wagoner and Pritish Kamat.

Not being able to measure exactly how much surface viscosity affects drop formation has put limits on making machines safer and more precise, said Basaran, who directs a center that works to resolve the science behind problems in manufacturing machinery.

Solutions provided by the center, called the Purdue Process Safety and Assurance Center, directly help partners in industries such as agriculture, health care and energy.

A better understanding of droplets and how to control them affects all those industries. Like crop spraying, inkjet printing in a factory produces tiny droplets that can get into the air and cause breathing problems.

More precise control of a liquid-like substance also could enhance a machine's performance, such as giving a 3D printer the ability to produce more reliable or detailed objects.

"A material with too high or too low surface viscosity can lead to bad outcomes in the manufacturing process. Knowing those measurements allows you to use different chemistries to make a material that doesn't lead to a surface viscosity that's going to result in a bad outcome," Basaran said.

Next, Basaran's team plans to incorporate this math formula into experiments for recommending new machine designs. The formula could also become a commercial instrument in the future, such as a smartphone app.

"This discovery opens up a lot of avenues for basic research that just weren't possible before," Basaran said.

Credit: 
Purdue University