Heavens

Long ago, all the continents were crammed together into one large land mass called Pangea. Pangea broke apart about 200 million years ago, its pieces drifting away on the tectonic plates -- but not permanently. The continents will reunite again in the deep future. And a new study, presented today during an online poster session at the meeting of the American Geophysical Union, suggests that the future arrangement of this supercontinent could dramatically impact the habitability and climate stability of Earth. The findings also have implications for searching for life on other planets.

The study, which has been submitted for publication, is the first to model the climate on a supercontinent in the deep future.

Scientists aren't exactly sure what the next supercontinent will look like or where it will be located. One possibility is that, 200 million years from now, all the continents except Antarctica could join together around the north pole, forming the supercontinent "Amasia." Another possibility is that "Aurica" could form from all the continents coming together around the equator in about 250 million years.

In the new study, researchers used a 3D global climate model to simulate how these two land mass arrangements would affect the global climate system. The research was led by Michael Way, a physicist at the NASA Goddard Institute for Space Studies, an affiliate of Columbia University's Earth Institute.

The team found that, by changing atmospheric and ocean circulation, Amasia and Aurica would have profoundly different effects on the climate. The planet could end up being 3 degrees Celsius warmer if the continents all converge around the equator in the Aurica scenario.

In the Amasia scenario, with the land amassed around both poles, the lack of land in between disrupts the ocean conveyor belt that currently carries heat from the equator to the poles. As a result, the poles would be colder and covered in ice all year long. And all of that ice would reflect heat out into space.

With Amasia, "you get a lot more snowfall," explained Way. "You get ice sheets, and you get this very effective ice-albedo feedback, which tends to lower the temperature of the planet."

In addition to cooler temperatures, Way suggested that sea level would probably be lower in the Amasia scenario, with more water tied up in the ice caps, and that the snowy conditions could mean that there wouldn't be much land available for growing crops.

Aurica, by contrast, would probably be a bit beachier, he said. The land concentrated closer to the equator would absorb the stronger sunlight there, and there would be no polar ice caps to reflect heat out of Earth's atmosphere -- hence the higher global temperature.

Although Way likens Aurica's shores to the paradisiacal beaches of Brazil, "the inland would probably be quite dry," he warned. Whether or not much of the land would be farmable would depend on the distribution of lakes and what types of precipitation patterns it experiences -- details that the current paper doesn't delve into, but could be investigated in the future.

The simulations showed that temperatures were right for liquid water to exist on about 60% of Amasia's land, as opposed to 99.8% of Aurica's -- a finding that could inform the search for life on other planets. One of the main factors that astronomers look for when scoping out potentially habitable worlds is whether or not liquid water could survive on the planet's surface. When modeling these other worlds, they tend to simulate planets that are either completely covered in oceans, or else whose terrain looks like that of modern-day Earth. The new study, however, shows that it's important to consider land mass arrangements while estimating whether temperatures fall in the 'habitable' zone between freezing and boiling.

Although it may be 10 or more years before scientists can ascertain the actual land and sea distribution on planets in other star systems, the researchers hope that having a larger library of land and sea arrangements for climate modeling could prove useful in estimating the potential habitability of neighboring worlds.

As temperatures rise due to climate change, the melting of polar ice sheets is accelerating. An international team of researchers led by geoscientist Dr Kim Jakob from Heidelberg University has now examined the dynamics of the East Antarctic Ice Sheet more closely. This is by far the largest ice mass on Earth and is assumed to be less sensitive to climate change than other ice sheets simply because of its size. The researchers analysed data that they had obtained from deep-sea sediments dating back approximately 2.5 million years. This enabled them to determine the factors responsible for the stability of the East Antarctic Ice Sheet. The findings indicate that the ice masses of East Antarctica could be much less stable in a constantly warming climate than previously thought.

"The melting of polar ice sheets leads to a rise in global sea level, which is becoming an ever greater threat to coastal areas," explains Dr Jakob from the Institute of Earth Sciences at Heidelberg University. To better understand past changes in the large ice masses of East Antarctica, her research team performed geochemical analyses on deep-sea sediments from the Atlantic Ocean. The sediments were obtained through the Integrated Ocean Drilling Program (IODP), an international consortium of scientists formed to explore the ocean floor.

These analyses enabled the reconstruction of global sea-level change from approximately 2.8 to 2.4 million years ago, which in turn reflects variations in the total volume of ice. During this period, high atmospheric CO2 concentrations with values similar to those predicted for the near future decreased to a level comparable to the pre-industrial CO2 content of the atmosphere. The investigation reveals for the first time that the East Antarctic Ice Sheet achieved an unprecedented increase in stability approximately 2.5 million years ago compared to older periods in the Earth's history.

Factors conventionally accepted to have promoted the growth and decay of polar ice sheets during the Earth's history are the intensity of solar radiation and the CO2 content of the atmosphere. However, Dr Jakob and her team have now found an additional factor that played a decisive role in stabilising the East Antarctic Ice Sheet - the formation of large glaciers in the northern hemisphere, which caused global sea level to fall. This sea-level fall reduced the exposure of East Antarctic ice to relatively warm ocean waters and thus minimised the potential of sea water to cause basal melt in parts of the ice sheet.

The findings of the study contribute to a better understanding of the dynamics of global ice sheets under elevated atmospheric CO2 concentrations, as expected for the near future. Further melting of ice masses in the northern hemisphere due to anthropogenic climate change and subsequent rising global sea levels could contribute to a renewed destabilisation of the ice sheet in East Antarctica.

Besides scientists from Heidelberg University, researchers from Goethe University Frankfurt, the Max Planck Institute for Chemistry in Mainz and the University of Southampton (Great Britain) contributed to this study. The research was funded in the context of the IODP priority programme of the German Research Foundation. The findings were published in the journal Proceedings of the National Academy of Sciences of the United States of America.

Giant planets that developed early in a star system's life could solve a mystery of why spiral structures are not observed in young protoplanetary discs, according to a new study by University of Warwick astronomers.

The research, published today (26 November) in the Astrophysical Journal Letters and part supported by the Royal Society, provides an explanation for the lack of spiral structure that astronomers expect to see in protoplanetary discs around young stars that also suggests that scientists may have to reassess how quickly planets form in a disc's lifecycle.

Protoplanetary discs are the birthplaces of planets, harbouring the material that will eventually coalesce into the array of planets that we see in the Universe. When these discs are young they form spiral structures, with all their dust and material dragged into dense arms by the massive gravitational effect of the disc spinning. A similar effect occurs at the galactic level, hence why we see spiral galaxies such as our own, the Milky Way.

Over the course of three to ten million years material from the disc comes together to form planets, falls onto the star it is orbiting or just disperses into space through winds coming off the disc. When a disc is young it is self-gravitating, and the material within it forms a spiral structure which it loses when it becomes gravitationally stable. Young planets that develop then carve out gaps in the disc as they consume and disperse material in their way, resulting in the 'ring and gap' features that astronomers most commonly see in protoplanetary discs.

But astronomers have struggled to account for observations of young protoplanetary discs that show no signs of spirals, but instead look like a disc much older with a ring and gap structure. To provide an explanation, Sahl Rowther and Dr Farzana Meru from the University of Warwick Department of Physics conducted computer simulations of massive planets in young discs to determine what would happen when they interacted.

They found that a giant planet, around three times the mass of Jupiter, migrating from the outer regions of the disc towards its star would cause enough disruption to wipe out the disc's spiral structure with results much like the discs observed by astronomers. However, to be present in the spiral stage of the disc those planets would have to form rapidly and early in the disc's lifecycle.

Lead author Sahl Rowther, PhD student in the Department of Physics, said: "When discs are young, we expect them to be massive with spiral structures. But we don't see that in observations.

"Our simulations suggest that a massive planet in one of these young discs can actually shorten the time spent in the self-gravitating spiral phase to one that looks more like some of the observations that astronomers are seeing.

Co-author Dr Farzana Meru from the Department of Physics adds: "If some of these discs that astronomers are observing were recently self-gravitating then that suggests they formed a planet while the disc was still young. The self-gravitating phase for a protoplanetary disc is much less than about half a million years, which means the planet would have to have formed incredibly quickly.

"Irrespective of what mechanism explains how these planets form, this probably means that we have to consider that planets form much faster than originally thought."

Their simulations modelled a giant planet in the outer regions of a protoplanetary disc as it migrates inwards, a process that astronomers expect to see as the torque pushes the planet inwards as it exchanges angular momentum with the gas in the disc. This also means that the planet would interact with and disrupt a large proportion of the disc and be massive enough to open a gap in the gas, resulting in the ring and gap structure.
Sahl Rowther adds: "This is exciting given the unknowns associated with the masses of observed discs. If massive discs with ring and gap structures are common, it could provide more pathways in explaining disc architectures.

"Our results suggest that it may even be possible to see signs of these giant planets, given the right conditions and technology. The next stage of our research will be to determine what those conditions are, to help astronomers in trying to determine the presence of these planets."

Dr Meru adds: "It's quite possible for that spiral structure to be wiped out, don't be fooled when you look at a disc. It could still be reasonably massive, it's just that a giant planet has caused it to lose its spirals.

"We have these amazing images of protoplanetary discs and what's really exciting about them is their structure. In the past few years telescopes have become very powerful and we're able to see features like gaps and rings. With computer simulations like ours, we can now try to understand if some of the processes that we expect to happen, like planets migrating in young discs, can lead to the kind of images that observers are seeing. This is possible with the combination of powerful telescopes and supercomputers."

The uranium-bearing mineral zircon is an abundant constituent of Earth's continental crust, providing information about the age and origin of the continents and large geological features such as mountain chains and giant volcanoes. But unlike Earth, Mars's crust is not evolved and is compositionally similar to the crust found under the Earth's oceans, where zircon is rare. Therefore, zircon is not expected to be a common mineral on Mars.

"We were quite surprised and excited when we found so many zircons in this martian meteorite. Zircon are incredible durable crystals that can be dated and preserve information that tell us about their origins. Having access to so many zircons is like opening a time window into the geologic history of planet," describes Professor Martin Bizzarro from the GLOBE Institute, who led the study.

The team investigated the ancient Martian meteorite NWA 7533 (Figure 1), dubbed "Black Beauty", which was discovered in the desert of Morocco in 2011. After crushing 15 grams of this rock, they extracted about 60 zircons. By age-dating the zircons, they found that the majority of crystals date back to about 4.5 billion years ago, namely the very beginning of the planet's life. But they also made an unexpected discovery: some of the zircons defined much younger ages, ranging from about 1500 million years down to 300 million years.

"These young ages were a great surprise", says Bizzarro. "The Black Beauty meteorite is believed to come from the southern hemisphere of Mars, which does not have any young volcanic terrains. The only possible source for these young zircons is the Tharsis volcanic province located in the northern hemisphere of the planet, which contains large volcanoes that were recently active," Martin Bizzarro adds.

The Tharsis bulge on Mars is an enormous volcanic province that hosts the largest volcanoes in the Solar System, which are up to 21 km high. Scientists believe that this volcanic province is the expression of very deep magmatism that erupts on the planets surface. The analogy on Earth is the Hawaiian volcanic chain of islands, which is also believed to reflect deep-seated volcanic activity. But because of plate tectonics, the Pacific Plate is constantly moving such that, instead of accumulating at one single location, a chain of progressively younger volcanic islands has formed. Since Mars does not have plate tectonics, the volcanoes pile up at one single location and as a result grow to gigantic sizes.

If Bizzarro's team is correct, it means that the young zircons may contain information about the deep, inaccessible interior of Mars. This is the first time that scientists have direct access to the deep interior of the red planet via these samples, which may allow them to uncover the internal structure and composition of Mars.

"Having samples of the deep interior of Mars is key. This means that we can now use these zircons to probe the origin of the volatile elements on Mars, including its water, and see how it compares with Earth and other planets in the Solar System," explains Mafalda Costa, first other of the new study.

But to understand the nature of the deep martian interior, the researchers turned to the analysis of the isotopic composition of the element hafnium in the same zircons.

"Because hafnium is a major elemental constituent of zircon, it retains a memory of where the zircon formed," says Martin Bizzarro. "We found that the hafnium isotope composition of the young zircons is unlike any of the known Martian meteorites, which indicates that the young zircons come from a primitive reservoir that we did not know existed in the interior of Mars," he adds.

The hafnium isotope composition of the young zircons is similar to the most primitive objects in the Solar System, that is, chondrite meteorites. These chondrite meteorites are samples of asteroids that have never been modified since their formation. This implies that the deep interior of Mars has essentially not been modified since the formation of the planet (Figure 2). The existence of such a primitive reservoir is expected for a planet lacking plate tectonics. In contrast to Earth, where material formed at surface is continuously recycled into the interior by plate tectonics, the deep interior of Mars has remained unchanged since the birth of the planet and, as such, preservers its initial composition.

Finally, the discovery that zircon may be abundant on the Martian surface may guide the future robotic exploration of the planet, especially in the framework of returning samples to Earth.

"Our study makes clear that a return mission targeted at acquiring zircon-bearing samples will be of high scientific value towards understanding the geologic history of Mars," concludes Martin Bizzarro.

The strong interaction is one of the fundamental forces of nature, which binds quarks into hadrons such as the proton and the neutron, the building blocks of atoms. According to the quark model, hadrons can be formed by two or three quarks, called mesons and baryons respectively and collectively referred to as conventional hadrons. The quark model also allows for the existence of so-called exotic hadrons, composed by four (tetraquarks), five (pentaquarks) or more quarks. A rich spectrum of exotic hadrons is expected just as for the conventional ones. However, no unambiguous signal of exotic hadron was observed until 2003, when the X(3872) state was discovered by the Belle experiment. In the following years, a few more exotic states were discovered. The explanation of their properties requires the existence of four constituent quarks. Identification of pentaquark states is even more difficult, and the first candidates were observed by the LHCb experiment in 2015. All these known states contain at most two heavy quarks, the beauty or charm quark.

Recently, by studying the invariant mass distribution of two J/? mesons produced in proton-proton collisions at center-of-mass energies up to 13 TeV, the LHCb collaboration observed two structures. The narrower structure is described as a hadron state of mass about 6900 MeV/c2, denoted as X(6900). As the J/? meson contains a charm (c) and an anticharm quark (\bar{c}), the new state suggests a minimal quark content of cc\bar{c}\bar{c}, making it a candidate of four-charm tetraquark states. The other structure, being broad and close to twice the J/? rest mass, can be due to another tetraquark of larger width or a combination of several overlapping tetraquark states.

"It is very exciting to see the first experimental evidence of a four-charm tetraquark. The unique composition of the new state makes it an ideal laboratory to gain insight into the strong interaction inside hadrons," says the LHCb physicist working at the INFN section of Florence, Liupan An.

While the quantum chromodynamics (QCD) is the commonly used theory to describe the strong interaction, understanding of the internal structure of a hadron is not yet possible from first-principle calculations. Models that approximate QCD are introduced to explain the binding mechanism of quarks into hadrons. In the molecular picture, an exotic state is formed by two weakly bound conventional hadrons like the deuteron. The molecular structure is currently the favoured interpretation of the narrow pentaquarks observed by LHCb and the X(3872) state. However, hadronic states made solely from heavy quarks are expected to be tightly bounded, for example, a four-charm tetraquark is usually considered to be formed by a cc-diquark and a\bar{c}\bar{c}-antidiquark attracting each other. The cc-diquark model successfully predicted the mass of the Ξcc++ baryon observed by LHCb in 2017. Rescattering of known hadrons through the strong interaction is also possible to create structures that look like a hadron state. The nature of the newly observed four-charm states is yet to be determined even though a compact tetraquark interpretation is preferred.

"The LHCb observation opens a new window for studies of multiquark hadron spectroscopy. More studies from both experimental and theoretical physicists will provide the opportunity to understand the nature of the four-charm state," says Yanxi Zhang, working on the LHCb experiment at the Peking University.

"If the four-heavy-quark interpretation is correct, a full spectrum of these tightly bound states is expected to be discovered from the data that LHCb will be able to collect in the near future. Measurements of the masses and widths of these states, which can be predicted in QCD with relatively high precision, will provide a probing test of our understanding of the fundamental interactions between hadrons." adds Giacomo Graziani from INFN Florence.

LHCb is one of the four big experiments located at the most powerful particle accelerator in the world, the Larger Hadron Collider (LHC) at CERN. The LHCb experiment is dedicated to precision measurements of particles containing charm or beauty quarks, aiming at exploring the matter-antimatter asymmetry puzzle, looking for indirect evidence of new physics, and probing the strong interaction. The collaboration consists of more than 1400 physicists and engineers from all over the world.

"This is an important step forward in exploring the internal structure and dynamics of hadrons." said Prof. Yuanning Gao, leader of the Chinese LHCb group, "The LHCb experiment has again demonstrated its capability in heavy flavour spectroscopy, and will continue contributing to the understanding of the strong interaction."

The strong interaction keeps surprising us with new structures and new phenomena after several decades of questing and will surely do it again in the future.

The emergence of life is a mystery. Nevertheless, researchers agree that water is a precondition for life. The first cell emerged in water and then evolved to form multicellular organism. The oldest known single-cell organism on Earth is about 3.5 billion years old.

So far, so good. But if life emerged in water, where did the water come from?

"There are two hypotheses about the emergence of water. One is that it arrives on planets by accident, when asteroids containing water collide with the planet in question," says Professor Martin Bizzarro from the Centre for Star and Planet Formation at the Faculty of Health and Medical Sciences, University of Copenhagen.

Together with Assistant Professor Zhengbin Deng he has headed a new study that turns the theory about the emergence of water upside down.

"The other hypothesis is that water emerges in connection with the formation of the planet. Our study suggests that this hypothesis is correct, and if that is true, it is extremely exciting, because it means that the presence of water is a bioproduct of the planet formation process," Martin Bizzarro explains.

If Martin Bizzarro and Zhengbin Deng's theory proves correct, life in planetary systems may have had better chances of developing than previously assumed.

The researchers' studies show that there was water on Mars for the first 90 million years of the planet's existence. In astronomical time, this is a long time before water-rich asteroids bombarded the planets of the inner Solar System like Earth and Mars, according to the first hypothesis. And this is very sensational', Martin Bizzarro explains.

"It suggests that water emerged with the formation of Mars. And it tells us that water may be naturally occurring on planets and does not require an external source like water-rich asteroids," he says.

The study is based on analyses of an otherwise modest black meteorite. But the meteorite is 4.45 billion years old and contains invaluable knowledge about the young solar system. Black Beauty, which is the name of the meteorite, originates from the original Martian crust and offers unique insight into events at the time of the formation of the solar system.

"It is a gold mine of information. And extremely valuable," says Martin Bizzarro. After having been discovered in the Moroccan desert, the meteorite was sold for USD 10,000 dollars per gram.

With help from funds, Martin Bizzarro managed to buy just under 50 grams for research purposes back in 2017. With the meteorite in the laboratory they are now able to present signs of the presence of liquid water on Mars at the time of its formation. First, however, they had to crush, dissolve and analyse 15 grams of the expensive rock, Zhengbin Deng explains:

"We have developed a new technique that tells us that Mars in its infancy suffered one or more severe asteroid impacts. The impact, Black Beauty reveals, created kinetic energy that released a lot of oxygen. And the only mechanism that could likely have caused the release of such large amounts of oxygen is the presence of water," Zhengbin Deng says.

Another bone of contention between researchers is how Mars with its cold surface temperature could accommodate liquid water causing the depositions of rivers and lakes visible on the planet today. Liquid water is a precondition for the assembling of organic molecules, which is what happened at least 3.5 billion years ago at the emergence of life on Earth.

The researchers' analysis of Black Beauty shows that the asteroid impact on Mars released a lot of greenhouse gasses into the atmosphere.

According to Zhengbin Deng, 'this means that the CO2-rich atmosphere may have caused temperatures to rise and thus allowed liquid water to exist at the surface of Mars'.

The team is now doing a follow-up study examining the microscopic water-bearing minerals found in Black Beauty. The age-old watery minerals are both original and unchanged since their formation, which means that the meteorite has witnessed the very emergence of water.

DALLAS, Nov. 9, 2020 -- Smoking marijuana increases the risk of complications after cardiovascular procedures, and marijuana users who had a heart attack or cardiac intervention were more likely to be readmitted to the hospital for recurrent heart attacks or coronary procedures, according to two preliminary studies to be presented at the American Heart Association's Scientific Sessions 2020. The meeting will be held virtually, Friday, November 13-Tuesday, November 17, 2020, and is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science for health care worldwide.

Using marijuana (also known as cannabis) is becoming more prevalent in the U.S., as numerous states have legalized it for recreational or medicinal use. However, research indicates marijuana has substantial risks and no benefits for cardiovascular health, and little is known about the safety of smoking marijuana for people with heart disease, according to a 2020 American Heart Association Scientific Statement. Two new studies, by separate researchers, explored how marijuana use affects patients with cardiovascular disease.

Not So Harmless: Marijuana Use and In-hospital Outcomes After Percutaneous Coronary Intervention: Insights From the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (Presentation P1916)

Michigan researchers investigated whether patients who smoked marijuana are at an increased risk of complications after percutaneous coronary intervention (PCI) procedures compared with those who did not smoke marijuana. PCI, which includes angioplasty and stent placement, is a non-surgical procedure to open a blocked heart artery and restore blood flow to the heart.

"As marijuana is becoming more accessible across the U.S., there is a need for rigorous research to better understand the effects of marijuana use on cardiovascular health," said Sang Gune Yoo, M.D., internal medicine resident physician at the University of Michigan and lead author of the study.

Researchers used a state-wide registry of more than 113,000 patients in Michigan who underwent angioplasty from January 2013 to October 2016. Nearly 4,000 people, or 3.5% of those in the study, reported smoking marijuana within a month of a PCI procedure, however, they did not specify if the marijuana had been prescribed. Medical marijuana - prescribed use for a medical condition - has been legal in Michigan since 2008, and recreational marijuana was legalized in Michigan in 2018 (after the time period of this study).

Patients who smoked marijuana and underwent angioplasty were average age of 54, 79% male and 73% of them also smoked cigarettes. They had fewer traditional risk factors for heart disease, such as high cholesterol, diabetes or high blood pressure.

After adjusting for differences between patients who did or did not smoke marijuana, researchers found:

Smoking marijuana was associated with a higher risk of stroke after PCI. "However, this should be interpreted with caution due to the overall very low rate of stroke after PCI," Yoo said.

Marijuana smokers had an approximately 50% increased risk of bleeding after PCI.

Patients who smoked marijuana had a decreased risk of acute kidney injury compared with those who did not smoke.

There were no significant differences in the risk of death or the need for blood transfusion between groups.

"Although people who smoke marijuana may be at higher risk for complications such as stroke and post-PCI bleeding, this should not deter patients who use or have used marijuana from pursuing potentially life-saving PCI procedures," Yoo said. "As marijuana use continues to increase, medical professionals and patients should be aware of these increased risks of complications after PCI. Physicians should screen and counsel patients about marijuana prior to their procedure due to the risks of serious complications."

Senior study author Devraj Sukul, M.D., M.S., an interventional cardiologist at the University of Michigan, noted that, "understanding whether the effects of marijuana are dose-dependent or related to the method of intake are two important limitations of this study and remain important questions for future research."

Co-authors with Yoo and Sukul are Milan Seth, M.S., Thomas Earl, M.D., Cyril Ruwende, M.D., Ph.D., Milind Karve, M.D.; Ibrahim Shah, M.D.; Thomas Hill, M.D.; and Hitinder S. Gurm, M.D. Author disclosures are in the abstract.

The Blue Cross Blue Shield Michigan Cardiovascular Consortium (BMC2) coordinating center is supported by a grant from Blue Cross Blue Shield of Michigan to the University of Michigan. The sponsor had no role in the study design or decision to publish this work.

Note: Session EP.APS.11 - Social and Behavioral Risk Factors for Cardiovascular Disease

Prevalence, Trends and Impact of Cannabis Use on Hospitalizations With Prior Myocardial Infarction and Revascularization (Presentation P380)

This multi-center study assessed the prevalence and impact of marijuana use on hospital admissions for patients with previous heart attacks and revascularization procedures. Revascularization refers to restoring blood flow to the heart and includes non-surgical interventions such as percutaneous coronary intervention (PCI) as well as coronary artery bypass grafting (CABG). CABG is a surgical procedure to restore normal blood flow to a blocked coronary artery.

Researchers examined the National Inpatient Sample, the largest publicly accessible database in the U.S., to assess the rate of hospital admissions in patients with a history of previous heart attack, PCI and/or CABG, and self-identified marijuana users and non-users from 2007-2014. The database, which includes about 8 million hospital stays each year, does not include details about smoking or eating or other forms of marijuana consumption. Numerous states legalized or decriminalized medical and/or recreational marijuana during the study's time frame.

The analysis found:

a 250% relative increase in cannabis use among patients who had survived a heart attack or revascularization;

67% of the heart attack survivors who used cannabis had a subsequent heart attack vs. 41% of non-cannabis users; and

cannabis users had higher rates of hospitalizations for recurrent PCI and CABG.

Marijuana users were more likely to be middle aged (median age 52 compared to median age 72 for non-users); Black Americans (34% vs. 10% of non-users); and male (77% vs. 62% of non-users). In addition, cannabis users had significantly lower rates of high blood pressure, diabetes and high cholesterol, however, it is unclear why these risk factors were low.

"There was an alarming rise in the trend of cannabis use among patients who have already had a heart attack or coronary revascularization procedure during the study period," said the study's lead author Rushik Bhuva, M.D., a cardiology fellow with the Wright Center for Community Health in Scranton, Pennsylvania. "Another concerning finding was that the frequency of recurrent heart attacks and cardiac interventions was higher among cannabis users, even though they were younger and had fewer risk factors for heart disease.

"Spreading awareness regarding the potential risk of recurrent heart attacks in middle-aged, African American and male cannabis users and screening them at an earlier age for potential risk factors of future heart attacks should be encouraged among clinicians," said Bhuva. "In addition, the role of medicinal cannabis, its benefits and potential risks with regards to cardiovascular management need to be validated in larger studies."

A collaboration between the LOw Frequency ARray (LOFAR) radio telescope in Europe, the Gemini North telescope, and the NASA InfraRed Telescope Facility (IRTF), both on Maunakea in Hawai'i, has led to the first direct discovery of a cold brown dwarf from its radio wavelength emission. Along with paving the way for future brown dwarf discoveries, this result is an important step towards applying radio astronomy to the exciting field of exoplanets.

For the first time, astronomers have used observations from the LOFAR radio telescope, the NASA IRTF, operated by the University of Hawai'i, and the international Gemini Observatory, a Program of NSF's NOIRLab, to discover and characterize a cold brown dwarf. The object, designated BDR J1750+3809, is the first substellar object to be discovered through radio observations -- until now, brown dwarfs have been uncovered in large infrared and optical surveys. Directly discovering these objects with sensitive radio telescopes such as LOFAR is a significant breakthrough because it demonstrates that astronomers can detect objects that are too cold and faint to be found in existing infrared surveys -- maybe even large free-floating exoplanets.

"In this discovery, Gemini was particularly important because it identified the object as a brown dwarf and also gave us an indication of the temperature of the object," explained lead author Harish Vedantham of ASTRON, the Netherlands Institute for Radio Astronomy. "The Gemini observations told us that the object was cold enough for methane to form in its atmosphere -- showing us that the object is a close cousin of Solar System planets like Jupiter."

Brown dwarfs are substellar objects straddling the boundary between the largest planets and the smallest stars [1]. Occasionally dubbed failed stars, brown dwarfs lack the mass to trigger hydrogen fusion in their cores, instead glowing at infrared wavelengths with leftover heat from their formation. While they lack the fusion reactions that keep our Sun shining, brown dwarfs can emit light at radio wavelengths. The underlying process powering this radio emission is familiar, as it occurs in the largest planet in the Solar System. Jupiter's powerful magnetic field accelerates charged particles such as electrons, which in turn produces radiation -- in this case, radio waves [2] and aurorae.

The fact that brown dwarfs are radio emitters allowed the international collaboration of astronomers behind this result to develop a novel observing strategy. Radio emissions have previously been detected from only a handful of cold brown dwarfs -- and they have been known and cataloged by infrared surveys before being observed with radio telescopes. The team decided to flip this strategy, using a sensitive radio telescope to discover cold, faint sources and then perform follow-up infrared observations with a large telescope like the 8-meter Gemini North telescope to categorize them.

"We asked ourselves, 'Why point our radio telescope at cataloged brown dwarfs?'," said Vedantham. "Let's just make a large image of the sky and discover these objects directly in the radio."

Having found a variety of tell-tale radio signatures in their observations, the team had to distinguish potentially interesting sources from background galaxies. To do so, they searched for a special form of light that was circularly polarized [3] -- a feature of light from stars, planets, and brown dwarfs, but not from background galaxies. Having found a circularly polarized radio source, the team then turned to telescopes including Gemini North and the NASA IRTF to provide the measurements required to identify their discovery.

Gemini North is equipped with a variety of infrared instruments, one of which is usually kept ready to observe when an interesting astronomical opportunity arises. In the case of BDR J1750+3809, Gemini's mainstay infrared imager, the Near InfraRed Imager and spectrograph (NIRI) , was not available -- so Gemini astronomers took the unusual step of using the acquisition camera for the Gemini Near-Infrared Spectrograph (GNIRS) instead. Thanks to the careful work and foresight of Gemini staff, this camera provided deep, sharp, and accurate imaging at several infrared wavelengths.

"These observations really highlight the versatility of Gemini, and in particular the little-used 'keyhole' imaging capability of Gemini's GNIRS spectrograph," commented Gemini Observatory and University of Edinburgh astronomer Trent Dupuy -- a co-author of the research paper. The Gemini North observations were obtained via Director's Discretionary Time, which is reserved for programs needing small amounts of observing time with potentially high-impact results.

"This observation showcases both the flexibility and the power of the Gemini Observatories," said Martin Still of the National Science Foundation (NSF). "This was an opportunity where Gemini's design and operations enabled an innovative idea to develop into a significant discovery."

As well as being an exciting result in its own right, the discovery of BDR J1750+3809 could provide a tantalizing glimpse into a future when astronomers can measure the properties of exoplanets' magnetic fields. Cold brown dwarfs are the closest things to exoplanets that astronomers can currently detect with radio telescopes, and this discovery could be used to test theories predicting the magnetic field strength of exoplanets. Magnetic fields are an important factor in determining atmospheric properties and long term evolution of exoplanets.

"Our ultimate goal is to understand magnetism in exoplanets and how it impacts their ability to host life," concluded Vedantham. "Because magnetic phenomena of cold brown dwarfs are so similar to what is seen in Solar System planets, we expect our work to provide vital data to test theoretical models that predict the magnetic fields of exoplanets."

Most active volcanoes on Earth are dormant, meaning that they have not erupted for hundreds or even thousands of years, and are normally not considered hazardous by the local population. A team of volcanologists from the University of Geneva (UNIGE), working in collaboration with the University of Heidelberg in Germany, has devised a technique that can predict the devastating potential of volcanoes. The scientists used zircon, a tiny crystal contained in volcanic rocks, to estimate the volume of magma that could be erupted once Nevado de Toluca volcano (Mexico) will wake up from its dormancy. Up to 350 km3 of magma --about four times the volume of water stored in Lake Geneva-- are currently lying below Nevado de Toluca and their eruption could bring devastation. The new technique, applicable to most types of volcano across the globe, is described in the scientific journal Nature Communications.

The largest volcanic eruptions in the last 100 years were sourced from volcanoes that do not erupt frequently and therefore fly under the "radar" of scientists. Yet today, 800 million people around the world live close to volcanoes and are potentially at risk. A determining factor for the dangerousness of volcanoes is the volume of eruptible magma stored in their bellies, as this is related to the magnitude of future eruptions. Unfortunately, this magma is stored at inaccessible depths of 6-10 km and cannot be directly measured.

Tiny watches with a thermometer

The UNIGE volcanologists used a new approach combining zircon geochronology and thermal modelling to determine the volume of potentially-eruptible magma present in the volcanic reservoirs. "Zircon is a small crystal found in rocks erupted by volcanoes, and it contains uranium and thorium", begins Gregor Weber, a postdoctoral fellow at UNIGE and co-author of the study. "The decay of these radioactive elements allows us to date when they crystallised. Additionally, zircon crystallises only in a specific temperature range. With these two parameters, we can determine how fast the magma is cooling below a volcano. Like a pot of water, the larger the pot, the more time it takes to cool it. We analysed the zircons erupted over the last 1.5 million years by Nevado de Toluca thus determining the evolution of temperature of the magma stored below the volcano over time. This information can be converted into a volume of magma using thermal modelling." This approach has a resolution two times higher than that of existing techniques.

Sleeping monster

The methodology in the study was applied to the Mexican volcano Nevado de Toluca, also called Xinantécatl, a representative example of a dormant volcano located in the vicinity of Mexico City. The results were used to determine the maximum possible size of a future eruption from this volcano, which with 350 km3 could have potentially devastating effect. "The system can quickly wake up if the deep magma supply starts again," warns Weber.

Guiding the radars

This finding is essential for assessing volcanic risk quantitatively. "Knowing the size of a volcanic reservoir is important to identify volcanoes that are most likely to produce a large magnitude eruption in the future. Our method is a new way to evaluate the candidates for such eruptions," explains Weber. This approach is applicable to most types of volcanoes, whether active or dormant, and provides valuable insights into which volcanic systems need to be monitored more closely.

A team of European researchers discovered a new high-pressure mineral in the lunar meteorite Oued Awlitis 001, named donwilhelmsite [CaAl4Si2O11]. The team around Jörg Fritz from the Zentrum für Rieskrater und Impaktforschung Nördlingen, Germany and colleagues at the German Research Centre for Geoscience GFZ in Potsdam, Museum für Naturkunde Berlin, Natural History Museum Vienna, Institute of Physics of the Czech Academy of Science, Natural History Museum Oslo, University of Manchester, and Deutsches Zentrum für Luft und Raumfahrt Berlin published their findings in the scientific journal "American Mineralogist".

Besides the about 382 kilograms of rocks and soils collected by the Apollo and Luna missions, lunar meteorites allow valuable insights into the formation of the Moon. They are ejected by impacts onto the lunar surface and subsequently delivered to Earth.

Some of these meteorites experienced particularly high temperatures and pressures. The extreme physical conditions often led to shock melting of microscopic areas within these meteorites. These shocked areas are of great relevance as they mirror pressure and temperature regimes similar to those prevailing in the Earth's mantle. Therefore, the microscopic shock melt areas are natural crucibles hosting minerals that are otherwise naturally inaccessible at the Earth's surface. Minerals like wadsleyite, ringwoodite, and bridgmanite, constitute large parts of the Earth's mantle. Theses crystals were synthesized in high-pressure laboratory experiments. As natural minerals they were first described and named based on their occurrences in meteorites.

The new mineral donwilhelmsite is the first high-pressure mineral found in meteorites with application for subducted terrestrial sediments. It is mainly composed of calcium, aluminum, silicon, and oxygen atoms. Donwilhelmsite was discovered within shock melt zones of the lunar meteorite Oued Awlitis 001 found in 2014 in the Western Sahara. This meteorite is compositionally similar to rocks comprising the Earth's continents. Eroded sediments from these continents are transported by wind and rivers to the oceans, and subducted into the Earth's mantle as part of the dense oceanic crust. While being dragged deeper into the Earth mantle the pressure and temperature increases, and the minerals transform into denser mineral phases. The newly discovered mineral donwilhelmsite forms in 460 to 700 kilometre depth. In the terrestrial rock cycle, donwilhelmsite is therefore an important agent for transporting crustal sediments through the transition zone separating the upper and lower Earth's mantle.

This pan-European collaboration was essential to obtain the lunar meteorite, recognize the new mineral, understand its scientific relevance, and to determine the crystal structure of the tiny, the thousands part of a millimeter thick, mineral crystal with high accuracy. "At the GFZ, we used transmission electron microscopy to investigate microstructural aspects of the samples," says Richard Wirth from the section "Interface Geochemistry". "Our investigations and the crystal structure analyses of the colleagues from the Czech Republic once again underline the importance of transmission electron microscopy in the geosciences".

The new mineral was named in honor of the lunar geologist Don E. Wilhelms, an American scientist involved in landing site selection and data analyses of the Apollo space missions that brought to Earth the first rock samples from the Moon. Part of the meteorite Oued Awlitis 001, acquired by crowdfunding initiative „Help us to get the Moon!", is on display at the Natural History Museum Vienna.

PROVIDENCE, R.I. [Brown University] -- Planetary scientists from Brown University have developed a new remote sensing method for studying olivine, a mineral that could help scientists understand the early evolution of the Moon, Mars and other planetary bodies.

"Olivine is understood to be a major component in the interiors of rocky planets," said Christopher Kremer, a Ph.D. candidate at Brown University and lead author of a new paper describing the work. "It's a primary constituent of Earth's mantle, and it's been detected on the surfaces of the Moon and Mars in volcanic deposits or in impact craters that bring up material from the subsurface."

Current remote sensing techniques are good at spotting olivine from orbit, Kremer says, but scientists would like to do more than just spot it. They'd like to be able to learn more about its chemical makeup. All olivines have silicon and oxygen, but some are rich in iron while others have lots of magnesium.

"The composition tells us something about the environment in which the minerals formed, particularly the temperature," Kremer said. "Higher temperatures during formation yield more magnesium, while lower temperatures yield more iron. Being able to tease out those compositions could tell us something about how the interiors of these planetary bodies have evolved since their formation."

To find out if there might be a way to see that composition using remote sensing, Kremer worked with Brown professors Carlé Pieters and Jack Mustard, as well as mountains of data from the Keck/NASA Reflectance Experiment Laboratory (RELAB), which is housed at Brown.

One method researchers use to study rocks on other planetary bodies is spectroscopy. Particular elements or compounds reflect or absorb different wavelengths of light to various degrees. By looking at the light spectra rocks reflect, scientists can get an idea of what compounds are present. RELAB makes high-precision spectral measurements of samples for which the composition is already determined using other laboratory techniques. By doing that, the lab provides a ground truth for interpreting spectral measurements taken by spacecraft looking at other planetary bodies.

In poring through data from olivine samples examined over the years at RELAB, Kremer found something interesting hiding in a small swath of wavelengths that's overlooked by the kinds of spectroscopes that fly on orbital spacecraft.

"Over the past few decades, there's been a lot of interest in near infrared spectroscopy and middle infrared spectroscopy," Kremer said. "But there's a small range of wavelengths between those two that's left out, and those are the wavelengths I was looking at."

Kremer found that those wavelengths, a band between 4 and 8 microns, could predict the amount of magnesium or iron in an olivine sample to within about 10% of the actual content. That's far better than can be done when those wavelengths are ignored.

"With the instruments we have now, we could say maybe we have a little bit of this or a little bit of that," Mustard said. "But with this we're able to really put a number on it, which is a big step forward."

The researchers hope that this study, which is published in Geophysical Research Letters, might provide the impetus to build and fly a spectrometer that captures these previously overlooked wavelengths. Such an instrument could pay immediate dividends in understanding the nature of olivine deposits on the Moon's surface, Kremer says.

"The olivine samples brought back during the Apollo program that we've been able to study here on Earth vary widely in magnesium composition," Kremer said. "But we don't know how those differing compositions are distributed on the Moon itself, because we can't see those compositions spectroscopically. That's where this new technique comes in. If we could figure out a pattern to how those deposits are distributed, it could tell us something about the early evolution of the Moon."

There's the potential for other discoveries as well. The airplane-based SOFIA telescope is one of the few non-lab instruments that can look in this forgotten frequency range. The instrument's recent detection of water molecules in sunlit lunar surfaces made use of those frequencies.

"That makes the idea of space-borne spectrometers that can see this range much more attractive, both for water and for rocky material like olivine," Kremer said.

For the first time, over 250 million stars in our galaxy's bulge have been surveyed in near-ultraviolet, optical, and near-infrared light, opening the door for astronomers to reexamine key questions about the Milky Way's formation and history. Using ultraviolet data, and with 450,000 individual images, the team was able to measure the chemical composition of tens of thousands of stars spanning a large area of the bulge. The vast dataset can be explored in spectacular detail in this image.

The mysteries of the Milky Way are revealed in spectacular detail, thanks to the efforts of a team of astronomers who have observed 250 million stars in the bulge at the heart of the Milky Way using the Dark Energy Camera (DECam). DECam, primarily funded by the U.S. Department of Energy, is mounted on the Víctor M.Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile, a program of NSF's NOIRLab. By detecting the ultraviolet light from stars in the bulge known as Red Clump stars, they were able to analyze the chemical composition of over 70,000 stars over an area of sky 1,000 times as large as the full Moon (an area larger than 20 x 10 degrees stretching over the constellations Sagittarius and Scorpius).

The data are hosted and served to the community by NOIRLab's Community Science and Data Center (CSDC), also a program of NSF's NOIRLab, which handled the more than 7,000 DECam exposures, comprising more than 3.5 trillion pixels. A color-composite showing a main part of these data is shown in this image, and can be explored in all its whopping 50,000 x 25,000 pixels in this zoomable version.

The newly published study has shown that the stars near the very center of the Milky Way have a very similar composition, which suggests that they formed at around the same time. Normally composition is measured with a spectrograph, targeting a relatively small number of stars at a time (although the revolutionary DESI instrument at Kitt Peak National Observatory, a program of NSF's NOIRLab, will soon be able to do thousands). However, the Blanco DECam Bulge Survey took a different approach and instead precisely measured the stars' brightness differences from ultraviolet to infrared wavelengths. These differences in brightness at different wavelengths are called photometric colors by astronomers, and can reveal the composition of stars when the dataset is calibrated with stars measured spectroscopically.

The team used DECam's three square degree field of view to take over 450,000 individual images, before focusing on the subsample of 70,000 stars, which is substantially larger than previous spectroscopic bulge surveys. Future work with the full DECam data set will yield millions of composition measurements, a sample size more than 200 times that of even the largest spectroscopic surveys.

Kathy Vivas, co-author and NOIRLab astronomer said, "This is exactly the strength of the Dark Energy Camera -- to undertake these kinds of studies. While it was originally aimed at the study of the distant Universe to measure its expansion, DECam has proven to be a powerful instrument to study our Milky Way as well."

The survey results are providing key insights into the formation of the bulge and a glimpse of what is to come when the upcoming Vera C. Rubin Observatory begins acquiring its own images of the Milky Way. "Many other spiral galaxies look like the Milky Way and have similar bulges, so if we can understand how the Milky Way formed its bulge then we'll have a good idea of how the other galaxies did too," said Johnson.

These data would also surely have fascinated Víctor M. Blanco and his wife Betty Blanco, after whom the Blanco DECam Bulge Survey is named. Almost 50 years ago they used the same telescope to explore, amongst other things, the Milky Way's bulge. Half a century later, our home galaxy has plenty of surprises to offer.

Focusing ultrasound energy on a target site in the body to generate heat can burn and destroy the tissue in the site without a surgical procedure. This method is clinically applied to treat uterine fibroids, prostatic hyperplasia, prostate cancer, metastatic bone tumor and other types of tumor to destroy tumor cells using heat. However, there is a potential problem that the surrounding tissue may be burned in the process due to heat diffusion.

In 2019, at the Korea Institute of Science and Technology (KIST) Center for Bionics, Dr. Ki Joo Pahk's research team confirmed the possibility of precisely fractionating target tumor cells, as though it is cut out using a knife, without causing heat damage to any other part of the body by using high-intensity focused ultrasound (HIFU), an ultrasound with an acoustic pressure in megapascals (MPa) that is much more powerful than existing ultrasound, and revealed the mechanism behind the procedure.(?Ultrasonics Sonochemistry. 2019, 53, 164-177)

In the process of physically destroying the tissue without the use of heat, a boiling vapor bubble is generated at the target site of the HIFU, and it is by the kinetic energy of this primary vapor bubble that the target tumor tissue gets destroyed. However, during the process, cavitation bubble clouds can be subsequently generated between the boiling bubble and the HIFU transducer, leading to unwanted cell destruction. This made it necessary to identify the cause of their formation and to accurately predict the locations of their occurrence.

In order to reveal the mechanism of cavitation bubble clouds formation occurring when tumor tissue is removed by HIFU, the research team at KIST developed a mathematical model as part of their follow-up study and examined the impact of the primary boiling vapor bubble on nonlinear wave propagation. The results showed that the secondary generation of bubbles was caused by a constructive interference of the backscattered shockwave by the boiling bubble with the incoming incident shockwaves and it is within the range of this interference that the secondary bubbles formed. Based on the images obtained using a high-speed camera, it was found that the area where the interference occurred and the area where the secondary bubbles were generated were closely matched.

These findings not only explain the mechanism behind the secondary bubbles formation but also help predict where they will occur, thereby presenting the possibility of destroying target tissue with greater safety and precision.

Dr. Pahk from KIST said, "This study has shown that cavitation bubble clouds can be subsequently generated as a result of a shock scattering effect after a boiling vapor bubble forms where the ultrasound is focused. Using the mathematical developed in this study, it will be possible to predict the locations of bubble formation and the potential site that gets destroyed. I hope that the ultrasound technology under development will be developed in an ultra-precision focused ultrasound technology enabling physical destruction of only the tumor tissue, without the need for surgery, so that it can be applied clinically in the future."

Astronomers have found compelling evidence that planets start to form while infant stars are still growing. The high-resolution image obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) shows a young proto-stellar disk with multiple gaps and rings of dust. This new result, just published in Nature, shows the youngest and most detailed example of dust rings acting as cosmic cradles, where the seeds of planets form and take hold.

An international team of scientists led by Dominique Segura-Cox at the Max Planck Institute for Extraterrestrial Physics (MPE) in Germany targeted the proto-star IRS 63 with the ALMA radio observatory. This system is 470 light years from Earth and located deep within the dense L1709 interstellar cloud in the Ophiuchus constellation. Proto-stars as young as IRS 63 are still swaddled in a large and massive blanket of gas and dust called an envelope, and the proto-star and disk feed from this reservoir of material.

In systems older than 1,000,000 years, after the proto-stars have finished gathering most of their mass, rings of dust have been previously detected in great numbers. IRS 63 is different: at under 500,000 years old, it is less than half the age of other young stars with dust rings and the proto-star will still grow significantly in mass. "The rings in the disk around IRS 63 are so young," emphasizes Segura-Cox. "We used to think that stars entered adulthood first and then were the mothers of planets that came later. But now we see that proto-stars and planets grow and evolve together from early times, like siblings."

Planets face some serious obstacles during their earliest stages of formation. They have to grow from tiny dust particles, smaller than household dust here on Earth. "The rings in the disk of IRS 63 are vast pile-ups of dust, ready to combine into planets," notes co-author Anika Schmiedeke at MPE. However, even after the dust clumps together to form a planet embryo, the still-forming planet could disappear by spiraling inwards and being consumed by the central proto-star. If planets do start to form very early and at large distances from the proto-star, they may better survive this process.

The team of researchers found that there is about 0.5 Jupiter masses of dust in the young disk of IRS 63 further than 20 au from its center (at a distance similar to the Uranus orbit in our solar system). That is not counting the amount of gas, which could add up to 100 times more material. It takes at least 0.03 Jupiter masses of solid material to form a planet core that will efficiently accrete gas and grow to form a giant gas planet. Team member Jaime Pineda at MPE adds, "These results show that we must focus on the youngest systems to truly understand planet formation." For example, there is growing evidence that Jupiter may have actually formed much farther out in the Solar System, beyond the Neptune orbit, and then migrated inwards to its present location. Similarly, the dust surrounding IRS 63 shows that there is enough material far from the proto-star and at a stage young enough that there is a chance for this Solar System analogue to form planets in the way that Jupiter is suspected to have formed.

"The size of the disk is very similar to our own Solar System," Segura-Cox explains. "Even the mass of the proto-star is just a little less than our Sun's. Studying such young planet-forming disks around proto-stars can give us important insights into our own origins."

Controlling crop pests is a key element of agriculture worldwide, but the environmental impact of insecticides is a growing concern. Farmers have historically relied on the broad-spectrum chlorpyrifos, which is facing a potential ban in the U.S. A new article in Chemical & Engineering News, the weekly newsmagazine of the American Chemical Society, details how scientists are working to develop safer alternatives to chlorpyrifos.

Chlorpyrifos has been used for decades to kill arthropods on an array of crops, with upwards of five million kilograms used in the U.S. in 2014, according to the U.S. Department of Agriculture. Despite its effectiveness, there is evidence that the compounds in chlorpyrifos can cause health problems in humans, writes Senior Editor Britt E. Erickson. Both California and the European Union have recently banned the use of chlorpyrifos, and a full U.S. ban may be on the horizon. While there are other commercial pesticides that can take the place of chlorpyrifos for certain pests or crops, scientists are working to develop long-term pest control solutions that are safe for both consumers and the environment.

One possible solution is using biodegradable hydrogel beads laced with sugar water and a small amount of insecticide to deter ants from damaging citrus and grape orchards. Researchers are testing different types of insecticides in the beads with the goal of using a minimal amount for maximal effectiveness. Cotton production is impacted by the sticky residue left by aphids, leading scientists to test a series of insecticides that would target aphids and other "piercing" insects without harming pollinators and other beneficial insects. Other solutions include treating soil with insecticide before the crops begin to sprout, as well as targeting the roots of plants to minimize exposure in agricultural workers. Environmental groups are keeping a close eye on the emerging successors to chlorpyrifos, but researchers and growers alike are optimistic that they've found safer solutions to pest management.

The article, "Life After Chlorpyrifos," is freely available here.

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