Baltimore and Bullock’s Orioles Are Not Merging
A half-century of controversy over two popular bird species may have finally come to an end. In one corner: the Bullock’s Oriole, found in the western half of North America. In the other corner: the Baltimore Oriole, breeding in the eastern half. Where their ranges meet in the Great Plains, the two mix freely and produce apparently healthy hybrid offspring. But according to scientists from the Cornell Lab of Ornithology, hybridization is a dead end and both parent species will remain separate. Findings from the new study were published on August 1, 2020, in The Auk.
“The debate over whether Bullock’s and Baltimore Orioles are one species or two goes to the very heart of what defines a species,” said lead author Jennifer Walsh, a postdoctoral researcher at the Cornell Lab. “For a long time, that definition included the inability of one species to reproduce with any other. Bullock’s and Baltimore Orioles clearly can mate where their ranges overlap in the hybrid zone, but that’s not the whole story.”
The oriole conundrum began with the birds long considered to be two distinct species. But the discovery that they interbreed caused the Bullock’s and Baltimore Orioles to be lumped together under the name Northern Oriole in 1983, much to the consternation of birders and some biologists who felt that these birds were each highly distinct. In 1995, the American Ornithological Union reversed course and split them back into their two separate species. According to Cornell Lab researchers, this study may finally settle the lump-or-split debate.
The researchers examined genetic markers from almost 300 orioles (Bullock’s, Baltimore, and many hybrids) from the woodlands on the banks of the Platte River in Nebraska and Colorado. They found the oriole hybrid zone has been shrinking since it was first intensively studied in the 1950s. The scientists say if hybridization conferred any survival advantage, the zone would have gotten bigger, with more mixing of genes between the parent species, and more hybrids. Instead, ongoing natural selection pressures are limiting the expansion of the hybrid zone and preventing the homogenization of the two species.
“I call hybrid zones the ‘supercolliders of speciation,’” says Irby Lovette, co-author and director of the Lab’s Fuller Evolutionary Biology Program. “Through these special matings, genes and traits are mixing and matching in new combinations—all of which helps us learn more about where biodiversity comes from, and therefore how new species arise.”
The orioles are not alone in their flexible mating standards—about 10% of the world’s bird species hybridize. Hybrid zones exist in the U.S. for Black-capped and Carolina Chickadees, Indigo and Lazuli Buntings, and others. But not all hybrid zones are following the same pattern as that of the orioles. For example, Blue-winged- and Golden-winged Warblers have hybridized so much they may be moving toward a merger of the two species.
“We’re learning that hybrid zones are really very dynamic, shifting and changing over time,” said study author Shawn Billerman. “That aspect of hybrid zones has become recognized as common and widespread in the past 10 to 20 years with the rapid improvement in genetic sequencing.”
Though the scientists feel the one-or-two species matter is probably settled, there are other questions they want to pursue. Their next steps are to identify the specific factors that are limiting oriole hybrid expansion, sequence the entire genome for both Bullock’s and Baltimore Orioles, and determine the specific genes that cause differences in the appearance and behavior of the two orioles.
Reference: ” Genomic and plumage variation across the controversial Baltimore and Bullock’s oriole hybrid zone” by Jennifer Walsh, Shawn M Billerman, Vanya G Rohwer, Bronwyn G Butcher and Irby J Lovette, 1 August 2020, The Auk.
Water is a key substance in the meteorology of planets and is believed to play a key role in their formation. Terrestrial storms are driven by water dynamics creating lightning storms thought to be connected to regions where multiple phases of water co-exist (solid, liquid, and gas). As on Earth, Jupiter’s water is moved around by thunderstorms. Those are thought to form within the planet’s deep atmosphere, around 50 km below the visible clouds, where the temperature is close to 0Â°C. When these storms are powerful enough, they carry crystals of water-ice into the upper atmosphere.
In the first article, researchers from the US and the Laboratoire Lagrange suggest that when these crystals interact with gaseous ammonia, the ammonia acts as an anti-freeze, changing the ice to a liquid. On Jupiter as on Earth, a mixture of 2/3 water and 1/3 ammonia gas will remain liquid down to a temperature of -100°C. The ice crystals which have been lofted high into Jupiter’s atmosphere are melted by ammonia gas, forming a water-ammonia liquid, and become the seeds for exotic ammonia hailstones, dubbed ‘mushballs’ by the researchers. The mushballs being heavier then fall deeper into the atmosphere until they reach a point where they evaporate. This mechanism drags ammonia and water down to deep levels in the planet’s atmosphere.
Measurements by Juno discovered that while ammonia is abundant near Jupiter’s equator, it is highly variable and generally depleted elsewhere to very deep pressures. Prior to Juno, scientists saw evidence that parts of Jupiter’s atmosphere were depleted in ammonia to relatively shallow depths, but this had never been explained. To explain Juno’s discovery of ammonia’s deep variability across most of Jupiter, the researchers developed an atmospheric mixing model that is presented in a second article. Here they show that the presence of thunderstorms and the formation of water-ammonia mushballs dry out the deep atmosphere of its ammonia and account for the variations observed by Juno as a function of latitude.
In a third article, the researchers report observations of Jovian lightning flashes by one of Juno’s cameras. The small flashes appear as bright spots on the cloud tops, with sizes proportional to their depth in Jupiter’s atmosphere. Unlike previous missions that had only observed lightning flashes from deep regions, Juno’s proximity to the planet enabled it to detect smaller, shallower flashes. These flashes come from regions where temperatures are below -66°C and where water alone cannot be found in the liquid state. Yet the presence of a liquid is thought to be crucial to the lightning-generation process. Juno’s detection of “shallow lightning” storms at the altitudes where liquid ammonia-water can be created is observational support that the mushball mechanism may indeed be at work in Jupiter’s atmosphere.
Understanding the meteorology of Jupiter and of other as yet unexplored giant planets such as Uranus and Neptune should enable us to better comprehend the behaviour of gas giant exoplanets outside our own Solar System.
“Storms and the Depletion of Ammonia in Jupiter: I. Microphysics of ‘Mushballs’” by T. Guillot, D. J. Stevenson, S. K. Atreya, S. J. Bolton, H. N. Becker, 6 August 2020, JGR Planets.
“Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno Observations” by Tristan Guillot, Cheng Li, Scott J. Bolton, Shannon T. Brown, Andrew P. Ingersoll, Michael A. Janssen, Steven M. Levin, Jonathan I. Lunine, Glenn S. Orton, Paul G. Steffes and David J. Stevenson, 3 August 2020, JGR Planets.
“Small lightning flashes indicating shallow electrical storms on Jupiter” by H. N. Becker, J. W. Alexander, S. K. Atreya, S. J. Bolton, M. J. Brennan, S. T. Brown, A. Guillaume, T. Guillot, A. P. Ingersoll, S. M. Levin1, J. I. Lunine, Y. S. Aglyamov, P. G. Steffes, 6 August 2020, Nature.
Demand for integrated energy storage devices is growing rapidly as people rely more and more on portable and wireless electronics, and the global need grows for clean energy sources such as solar and wind energies.
This is creating an exponential need for advanced energy storage technologies — reliable and maintenance-free batteries and supercapacitors (SC) with high power density capability as storage devices. Supercapacitors are prominent candidates to meet this need due to their environmentally friendly and long cyclability characteristics.
Researchers from the Integrated Nano Systems Lab (INSys Lab), in the Centre for Clean Energy Technology, have been working on a pathway to improve the performance of supercapacitors, and meet that demand for increased storage capacity.
Dr. Mojtaba Amjadipour and Professor Francesca Iacopi (School of Data and Electrical Engineering) and Dr. Dawei Su (School of Mathematical and Physical Sciences) describe their cutting-edge work in the July 2020 issue of the journal Batteries and Supercaps. The prominence given to Graphitic-Based Solid-State Supercapacitors: Enabling Redox Reaction by In Situ Electrochemical Treatment – designated a Very Important Paper with front coverage placement — signifies just how innovative their research is in developing alternate ways to extend storage capacity
Dr. Iacopi said the multi-disciplinary approach within the team was beneficial in discovering what she says is a simple process.
“This research has originated from our curiosity of exploring the operation limits of the cells, leading us to unforeseen beneficial results. The control of this process would not have been possible without understanding the fundamental reasons for the observed improvement, using our team’s complementary expertise.”
Traditionally, supercapacitors are fabricated with liquid electrolytes, which cannot be miniaturized and can be prone to leakage, prompting research into gel-based and solid-state electrolytes. Tailoring these electrolytes in combination with carbon-based electrode materials such as graphene, graphene oxide, and carbon nanotubes is of paramount importance for an enhanced energy storage performance.
Graphene or graphitic carbon directly fabricated on silicon surfaces offers significant potential for on-chip supercapacitors that can be embedded into integrated systems. The research insights indicate a simple path to significantly enhance the performance of supercapacitors using gel-based electrolytes, which are key to the fabrication of quasi-solid-(gel) supercapacitors.
“This approach offers a new path to develop further miniaturized on-chip energy storage systems, which are compatible with silicon electronics and can support the power demand to operate integrated smart systems,” Dr. Iacopi said.
Reference: “Graphitic‐Based Solid‐State Supercapacitors: Enabling Redox Reaction by In Situ Electrochemical Treatment” by Dr. Mojtaba Amjadipour, Dr. Dawei Su and Prof. Francesca Iacopi, 17 June 2020, Batteries & Supercaps.
Batteries & Supercaps is published on behalf of Chemistry Europe, by Wiley VCH. Fields of interest include pure and applied battery research, battery electrochemistry, electrode materials, cell design, battery systems and applications, hybrid battery systems.
Half of All the Calcium in the Universe: Unprecedented Observations Shine Light on a Dying Star’s Final Moments
Calcium-rich supernova examined with X-rays for first time.
Half of all the calcium in the universe — including the very calcium in our teeth and bones — was created in the last gasp of dying stars.
Called “calcium-rich supernovae,” these stellar explosions are so rare that astrophysicists have struggled to find and subsequently study them. The nature of these supernovae and their mechanism for creating calcium, therefore, have remained elusive.
Now a Northwestern University-led team has potentially uncovered the true nature of these rare, mysterious events. For the first time ever, the researchers examined a calcium-rich supernova with X-ray imaging, which provided an unprecedented glimpse into the star during the last month of its life and ultimate explosion.
The new findings revealed that a calcium-rich supernova is a compact star that sheds an outer layer of gas during the final stages of its life. When the star explodes, its matter collides with the loose material in that outer shell, emitting bright X-rays. The overall explosion causes intensely hot temperatures and high pressure, driving a chemical reaction that produces calcium.
“These events are so few in number that we have never known what produced calcium-rich supernova,” said Wynn Jacobson-Galan, a first-year Northwestern graduate student who led the study. “By observing what this star did in its final month before it reached its critical, tumultuous end, we peered into a place previously unexplored, opening new avenues of study within transient science.”
“Before this event, we had indirect information about what calcium-rich supernovae might or might not be,” said Northwestern’s Raffaella Margutti, a senior author of the study. “Now, we can confidently rule out several possibilities.”
The research will be published today (August 5, 2020) in The Astrophysical Journal. Nearly 70 co-authors from more than 15 countries contributed to the paper.
Margutti is an assistant professor of physics and astronomy in Northwestern’s Weinberg College of Arts and Sciences and a member of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics). Jacobson-Galan is an NSF Graduate Research Fellow in Margutti’s transients research group.
‘A global collaboration was ignited’
Amateur astronomer Joel Shepherd first spotted the bright burst, dubbed SN2019ehk, while stargazing in Seattle. On April 28, 2019, Shepherd used his new telescope to view Messier 100 (M100), a spiral galaxy located 55 million light years from Earth. The next day, a bright orange dot appeared in the frame. Shepherd reported the anomaly to a community astronomical survey.
“As soon as the world knew that there was a potential supernova in M100, a global collaboration was ignited,” Jacobson-Galan said. “Every single country with a prominent telescope turned to look at this object.”
This included leading observatories in the United States such as NASA’s Swift Satellite, W.M. Keck Observatory in Hawaii and the Lick Observatory in California. The Northwestern team, which has remote access to Keck, was one of the many teams worldwide who triggered its telescopes to examine SN2019ehk in optical wavelengths. University of California Santa Barbara graduate student Daichi Hiramatsu was the first to trigger Swift to study SN2019ehk in the X-ray and ultraviolet. Hiramatsu also is a staff scientist at Las Cumbres Observatory, which played a crucial role in monitoring the long-term evolution of this supernova with its global telescope network.
The worldwide follow-up operation moved so quickly that the supernova was observed just 10 hours after explosion. The X-ray emission detected with Swift only lingered for five days and then completely disappeared.
“In the world of transients, we have to discover things very, very fast before they fade,” Margutti said. “Initially, no one was looking for X-rays. Daichi noticed something and alerted us to the strange appearance of what looked like X-rays. We looked at the images and realized something was there. It was much more luminous than anybody would have ever thought. There were no preexisting theories that predicted calcium-rich transients would be so luminous in X-ray wavelengths.”
‘The richest of the rich’
While all calcium comes from stars, calcium-rich supernovae pack the most powerful punch. Typical stars create small amounts of calcium slowly through burning helium throughout their lives. Calcium-rich supernovae, on the other hand, produce massive amounts of calcium within seconds.
“The explosion is trying to cool down,” Margutti explained. “It wants to give away its energy, and calcium emission is an efficient way to do that.”
Using Keck, the Northwestern team discovered that SN 2019ehk emitted the most calcium ever observed in a singular astrophysical event.
“It wasn’t just calcium rich,” Margutti said. “It was the richest of the rich.”
Uncovering new clues
SN2019ehk’s brief luminosity told another a story about its nature. The Northwestern researchers believe that the star shed an outer layer of gas in its final days. When the star exploded, its material collided with this outer layer to produce a bright, energetic burst of X-rays.
“The luminosity tells us how much material the star shed and how close that material was to the star,” Jacobson-Galan said. “In this case, the star lost a very small amount of material right before it exploded. That material was still nearby.”
Although the Hubble Space Telescope had been observing M100 for the past 25 years, the powerful device never registered the star — which was experiencing its final evolution — responsible for SN2019ehk. The researchers used the Hubble images to examine the supernova site before the explosion occurred and say this is yet another clue to the star’s true nature.
“It was likely a white dwarf or very low-mass massive star,” Jacobson-Galan said. “Both of those would be very faint.”
“Without this explosion, you wouldn’t know that anything was ever there,” Margutti added. “Not even Hubble could see it.”
Reference: “SN2019ehk: A double-peaked Ca-rich transient with luminous X-ray emission and shock-ionized spectral features” by Wynn V. Jacobson-Galán, Raffaella Margutti, Charles D. Kilpatrick, Daichi Hiramatsu, Hagai Perets, David Khatami, Ryan J. Foley, John Raymond, Sung-Chul Yoon, Alexey Bobrick, Yossef Zenati, Lluís Galbany, Jennifer Andrews, Peter J. Brown, Régis Cartier, Deanne L. Coppejans, Georgios Dimitriadis, Matthew Dobson, Aprajita Hajela, D. Andrew Howell, Hanindyo Kuncarayakti, Danny Milisavljevic, Mohammed Rahman, César Rojas-Bravo, David J. Sand, Joel Shepherd, Stephen J. Smartt, Holland Stacey, Michael Stroh, Jonathan J. Swift, Giacomo Terreran, Jozsef Vinko, Xiaofeng Wang, Joseph P. Anderson, Edward A. Baron, Edo Berger, Peter K. Blanchard, Jamison Burke, David A. Coulter, Lindsay DeMarchi, James M. DerKacy, Christoffer Fremling, Sebastian Gomez, Mariusz Gromadzki, Griffin Hosseinzadeh, Daniel Kasen, Levente Kriskovics, Curtis McCully, Tomás E. Müller-Bravo, Matt Nicholl, András Ordasi, Craig Pellegrino, Anthony L. Piro, András Pál, Juanjuan Ren, Armin Rest, R. Michael Rich, Hanna Sai, Krisztián Sárneczky, Ken J. Shen, Philip Short, Matthew R. Siebert, Candice Stauffer, Róbert Szakáts, Xinhan Zhang, Jujia Zhang and Kaicheng Zhang, 5 August 2020, The Astrophysical Journal.
The study, “SN2019ehk: A double-peaked Ca-rich transient with luminous X-ray emission and shock-ionized spectral features,” was supported by the National Science Foundation (award numbers DGE-1842165, PHY-1748958 and AST-1909796.)
Planet-forming environments can be much more complex and chaotic than previously expected. This is evidenced by a new image of the star RU Lup, made with the Atacama Large Millimeter/submillimeter Array (ALMA).
All planets, including the ones in our Solar System, are born in disks of gas and dust around stars, so-called protoplanetary disks. Thanks to ALMA we have stunning high-resolution images of many of these planet factories, showing dusty disks with multiple rings and gaps that hint at the presence of emerging planets. The most famous examples of these are HL Tau and TW Hydrae.
But disks are not necessarily as neatly arranged as these initial dust observations suggest. A new ALMA image of RU Lup, a young variable star in the Lupus constellation, revealed a giant set of spiral arms made of gas, extending far beyond its more well-known dust disk. This spiral structure – resembling a ‘mini-galaxy’ – extends to nearly 1000 astronomical units (au) from the star, much farther away than the compact dust disk that extends to about 60 au.
Previous observations of RU Lup with ALMA, which were part of the Disk Substructures at High Angular Resolution Project (DSHARP), already revealed signs of ongoing planet formation, hinted by the dust gaps in its protoplanetary disk. “But we also noticed some faint carbon monoxide (CO) gas structures that extended beyond the disk. That’s why we decided to observe the disk around the star again, this time focusing on the gas instead of the dust,” said Jane Huang of the Center for Astrophysics, Harvard & Smithsonian (CfA) and lead author on a paper published on August 3, 2020, in The Astrophysical Journal.
Protoplanetary disks contain much more gas than dust. While dust is needed to accumulate the cores of planets, gas creates their atmospheres.
In recent years, high-resolution observations of dust structures have revolutionized our understanding of planet formation. However, this new image of the gas indicates that the current view of planet formation is still too simplistic and that it might be much more chaotic than previously inferred from the well-known images of neatly concentric ringed disks
“The fact that we observed this spiral structure in the gas after a longer observation suggests that we have likely not seen the full diversity and complexity of planet-forming environments. We may have missed much of the gas structures in other disks,” added Huang.
Huang and her team suggest several scenarios that could possibly explain why the spiral arms appeared around RU Lup. Maybe the disk is collapsing under its own gravity, because it is so massive. Or maybe RU Lup is interacting with another star. Another possibility is that the disk is interacting with its environment, accreting interstellar material along the spiral arms.
“None of these scenarios completely explain what we have observed,” said team-member Sean Andrews of CfA. “There might be unknown processes happening during planet formation that we have not yet accounted for in our models. We will only learn what they are if we find other disks out there that look like RU Lup.”
Reference: “Large-scale CO spiral arms and complex kinematics associated with the T Tauri star RU Lup” by Jane Huang, Sean M. Andrews, Karin I. Öberg, Megan Ansdell, Myriam Benisty, John M. Carpenter, Andrea Isella, Laura M. Pérez, Luca Ricci, Jonathan P. Williams, David J. Wilner and Zhaohuan Zhu, 3 August 2020, The Astrophysical Journal.
The team is composed of Jane Huang, Sean M. Andrews, Karin I. Öberg and David J. Wilner (Center for Astrophysics | Harvard & Smithsonian), Megan Ansdell (NASA HQ), Myriam Benisty (Universidad de Chile/IPAG France), John M. Carpenter (Joint ALMA Observatory Chile), Andrea Isella (Rice University), Laura M. Pérez (Universidad de Chile), Luca Ricci (California State University Northridge), Jonathan P. Williams (University of Hawaii), and Zhaohuan Zhu (University of Nevada).
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
ALMA is a single telescope of revolutionary design, composed initially of 66 high-precision antennas, and operating at wavelengths of 0.32 to 3.6 mm. Its main 12-meter array has fifty antennas, each measuring 12 meters in diameter, which together act as a single telescope — an interferometer. An additional compact array of four 12-meter and twelve 7-meter antennas complements this. The 66 ALMA antennas can be arranged in different configurations, where the maximum distance between antennas can vary from 150 meters to 16 kilometers, which gives ALMA a powerful variable “zoom.” It is able to probe the Universe at millimeter and submillimeter wavelengths with unprecedented sensitivity and resolution, with a vision up to ten times sharper than the Hubble Space Telescope, and complementing images made using the VLT Interferometer.
The St. Patrick Bay ice caps in Canada have completely disappeared.
The St. Patrick Bay ice caps on the Hazen Plateau of northeastern Ellesmere Island in Nunavut, Canada, have disappeared, according to NASA satellite imagery. National Snow and Ice Data Center (NSIDC) scientists and colleagues predicted via a 2017 paper in The Cryosphere that the ice caps would melt out completely within the next five years, and recent images from NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have confirmed that this prediction was accurate.
Mark Serreze, director of NSIDC, Distinguished Professor of Geography at the University of Colorado Boulder, and lead author on the paper, first set foot on the St. Patrick Bay ice caps in 1982 as a young graduate student. He visited the ice caps with his advisor, Ray Bradley, of the University of Massachusetts.
“When I first visited those ice caps, they seemed like such a permanent fixture of the landscape,” said Serreze. “To watch them die in less than 40 years just blows me away.”
In 2017, scientists compared ASTER satellite data from July 2015 to vertical aerial photographs taken in August of 1959. They found that between 1959 and 2015, the ice caps had been reduced to only five percent of their former area, and shrank noticeably between 2014 and 2015 in response to the especially warm summer in 2015. The ice caps are absent from ASTER images taken on July 14, 2020.
The St. Patrick Bay ice caps were one-half of a group of small ice caps on the Hazen Plateau, which formed and likely attained their maximum extents during the Little Ice Age, perhaps several centuries ago. The Murray and Simmons ice caps, which make up the second half of the Hazen Plateau ice caps, are located at a higher elevation and are therefore faring better, though scientists predict that their demise is imminent as well.
“We’ve long known that as climate change takes hold, the effects would be especially pronounced in the Arctic,” said Serreze. “But the death of those two little caps that I once knew so well has made climate change very personal. All that’s left are some photographs and a lot of memories.”
Remaining Space Station Crew Busy With Fascinating Research: Free-Flying Robots, Planetary Bodies and Water Droplets
Free-flying robots, planetary bodies, and water droplets were just part of Tuesday’s research plan aboard the International Space Station. The Expedition 63 trio also serviced a variety of communications gear and life support systems.
NASA and its international partners are planning human missions to the Moon, Mars and beyond and the space station represents a big step in that effort. The orbiting lab provides a unique platform to learn about the long-term effects of microgravity on a variety of systems.
A set of cube-shaped, robot assistants are flying around on their own today inside Japan’s Kibo laboratory module. Engineers are looking at video and imagery downlinked from the Astrobee devices to understand how the autonomous free-flyers visualize and navigate their way around the station.
Commander Chris Cassidy took a look at dynamic granular material samples this morning that simulate planetary surfaces. The experiment is taking place inside ESA’s (European Space Agency) Columbus laboratory module and could inform future planetary exploration missions.
The veteran NASA astronaut also split his time between botany and fluid physics. Cassidy worked on the Plant Habitat-02 checking growth lights and installing an acoustic shield to protect the plants from station noises. Next, he moved onto commercial research to improve water conservation and water pressure techniques on Earth.
In the Russian segment of the station, the two cosmonaut flight engineers worked on their complement of orbital science and lab maintenance. Anatoly Ivanishin serviced video equipment and an air purifier before conducting Earth observations. Ivan Vagner collected air samples for microbial analysis and explored ways to improve interactions between mission controllers, students and space crews.
Observational studies have found no cardiovascular benefits associated with cannabis use. Cannabis use may be linked to an increased risk of heart attacks, atrial fibrillation and heart failure; however, additional studies need to be conducted to better understand the research findings. Cannabis is classified as a Schedule I drug by the U.S. Drug Enforcement Agency (DEA), which severely limits scientists from studying it. The chemicals in cannabis have been linked to an increased risk of heart attacks, heart failure and atrial fibrillation in observational studies; however, a full understanding of how use of cannabis affects the heart and blood vessels is limited by a lack of adequate research, according to a new Scientific Statement from the American Heart Association (AHA) published today in its flagship journal Circulation.
According to the statement, although cannabis, also known as marijuana, may be helpful for conditions such as spasticity associated with multiple sclerosis, among others, cannabis does not appear to have any well-documented benefits for the prevention or treatment of cardiovascular diseases. Preliminary studies have found that cannabis use could negatively impact the heart and blood vessels.
“Attitudes towards recreational and medicinal use of cannabis have changed rapidly, and many states have legalized it for medical and/or recreational use. Health care professionals need a greater understanding of the health implications of cannabis, which has the potential to interfere with prescribed medications and/or trigger cardiovascular conditions or events, such as heart attacks and strokes,” said Robert L. Page II, Pharm.D., M.S.P.H., FAHA, chair of the writing group for the statement and professor in the department of clinical pharmacy and the department of physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado.
A recent study cited in the statement suggests that cannabis use is present in 6% of heart attack patients under 50 years of age. Another study found that cannabis users ages 18 to 44 had a significantly higher risk of having a stroke compared to nonusers. “Unfortunately, most of the available data are short-term, observational and retrospective studies, which identify trends but do not prove cause and effect,” said Page.
The most common chemicals in cannabis include THC (tetrahydrocannabinolic acid), the component of the plant that induces a “high,” and CBD (cannabidiol), which can be purchased over the counter, but to date, the FDA has only approved one CBD-derived product. Importantly, the FDA has not approved any other cannabis, cannabis-derived, or cannabidiol (CBD) products currently available on the market.
Some studies have found that within an hour after cannabis is smoked, THC may induce heart rhythm abnormalities, such as tachycardia, premature ventricular contractions, atrial fibrillation and ventricular arrhythmias. Acutely, THC also appears to stimulate the sympathetic nervous system, which is responsible for the “fight or flight” response, resulting in a higher heart rate, a greater demand for oxygen by the heart, higher blood pressure while laying down and dysfunction within the walls of the arteries.
In contrast, studies on CBD, which does not produce a “high” or intoxication, have found associations with reduced heart rate, lower blood pressure, increased vasodilation (ability of the arteries to open), lower blood pressure and potentially reduced inflammation. Inflammation is linked to atherosclerosis, the slow narrowing of the arteries that underlies most heart attacks and, possibly strokes.
Smoking and inhaling cannabis, regardless of THC content, has been associated with cardiomyopathy (heart muscle dysfunction), angina (chest pain), heart attacks, heart rhythm disturbances, sudden cardiac death, and other serious cardiovascular conditions. In states where cannabis has been legalized, an increase in hospitalizations and emergency department visits for heart attacks has been observed.
The way cannabis is consumed may influence how it affects the heart and blood vessels. “Many consumers and health care professionals don’t realize that cannabis smoke contains components similar to tobacco smoke,” said Page. Smoking and inhaling cannabis, regardless of THC content, has been shown to increase the concentrations of blood carboxyhemoglobin (carbon monoxide, a poisonous gas) five-fold, and a three-fold increase in tar (partly burnt combustible matter), similar to the effects of inhaling a tobacco cigarette.
Carbon monoxide intoxication from inhaled tobacco or cannabis has been associated with several heart problems, such as heart muscle disease, chest pain, heart attacks, heart rhythm disturbances, and other serious conditions.
Cannabis use should be discussed in detail with a health care professional so that an individual’s potential health risks can be reviewed. “If people choose to use cannabis for its medicinal or recreational effects, the oral and topical forms, for which doses can be measured, may reduce some of the potential harms. It is also vitally important that people only use legal cannabis products because there are no controls on the quality or the contents of cannabis products sold on the street,” said Page.
In addition to the poisonous compounds in cannabis smoke, vaping cannabis may also result in serious health outcomes, especially when it is mixed with vitamin E acetate oils, which are linked to EVALI (e-cigarette or vaping product use-associated lung injury), the potentially fatal illness that emerged among e-cigarette users last year.
“People who use cannabis need to know there are potentially serious health risks in smoking or vaping it, just like tobacco smoke. The American Heart Association recommends that people not smoke or vape any substance, including cannabis products, because of the potential harm to the heart, lungs and blood vessels,” said Rose Marie Robertson, M.D., FAHA, the deputy chief science and medical officer for the American Heart Association and co-director of the AHA Tobacco Center for Regulatory Science.
The statement also discusses cannabis use among older adults, people diagnosed with cardiovascular diseases and other populations including youth. Some studies have suggested that cannabis use – both CBD and THC – may be safe and effective for older populations. Though they are the least likely to use cannabis, older adults often use it to reduce neuropathic pain (common among people with type 2 diabetes), improve quality of life and decrease prescription drug use (including opioids).
Additionally, benefits for patients with age-related diseases, including Parkinson’s and Alzheimer’s, have also been reported in some studies; however, there is very little research on the long-term effects of cannabis use among this group of people. Another concern about older adults using cannabis is the potential of interactions with other medications, including blood thinners (anti- coagulants), anti-depressants, antipsychotics, antiarrhythmics for heart rhythm abnormalities, and statin drugs, which reduce cholesterol levels.
For people diagnosed with heart disease, cannabis should be used with extreme caution because cannabis increases the heart’s need for oxygen at the same time as it decreases available oxygen supply, which could cause angina (chest pain). In addition, in some studies, cannabis triggered a heart attack in people with underlying heart disease. Other studies have linked cannabis use to a higher risk of strokes and heart failure.
Research into the effects of cannabis on the heart and blood vessels has been limited because cannabis is categorized as a Schedule I controlled substance by the U.S. Drug Enforcement Agency (DEA). Schedule I controlled substances are defined as having no accepted medical use, a high potential for abuse and an unacceptable safety profile. The AHA’s Scientific Statement suggests that the DEA remove cannabis from the Schedule I of the U.S. Controlled Substances Act so that it can be widely studied by scientists. Forty-seven U.S. states, the District of Columbia, and 4 of 5 U.S. territories allow some form of cannabis use, and its use has risen considerably over the past decade, particularly among people 18-25 years of age. Although many states have legalized medical and/or recreational cannabis use, cannabis growing, sales and use are illegal at the federal level, further complicating scientific research.
“We urgently need carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety as it becomes increasingly available and more widely used,” Page said. “The public needs fact-based, valid scientific information about cannabis’s effect on the heart and blood vessels. Research funding at federal and state levels must be increased to match the expansion of cannabis use – to clarify the potential therapeutic properties and to help us better understand the cardiovascular and public health implications of frequent cannabis use.”
Legalization of cannabis for medical purposes should align with patient safety and efficacy. Legalization for recreational use will remain a significant concern until more research can be conducted on the safety and long-term population health effects across the life course and the equity and social justice impact of these laws. In those states where cannabis is legal for recreational or medical purposes, there should be a robust public health infrastructure that is adequately funded and implemented to minimize its impact on CVD mortality especially among young people those who have heart disease. The statement calls for the federal government to create standardized labeling about the amount of THC and CBD and require it on all legal cannabis products.
The Association believes cannabis should be tightly integrated into comprehensive tobacco control and prevention efforts that include age restrictions for purchasing, retailer compliance, excise taxes, comprehensive smoke-free air laws, professional education, screening within the clinical environment – for example, when a patient is admitted to the hospital and routinely screened to avoid medication interactions or potential toxicity – and coverage of cessation treatment programs by insurers, Medicare and Medicaid. These efforts should be adequately funded, and at least some portion of the revenue from cannabis taxation should be directed toward programs and services that improve public health.
The statement was written on behalf of the American Heart Association’s Clinical Pharmacology and Heart Failure and Transplantation Committees of the Council on Clinical Cardiology; the Council on Basic Cardiovascular Sciences; the Council on Cardiovascular and Stroke Nursing; the Council on Epidemiology and Prevention; the Council on Lifestyle and Cardiometabolic Health; and the Council on Quality of Care and Outcomes Research.
Reference: “Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association” by Robert L. Page II, Larry A. Allen, Robert A. Kloner, Colin R. Carriker, Catherine Martel, Alanna A. Morris, Mariann R. Piano, Jamal S. Rana, Jorge F. Saucedo, and On behalf of the American Heart Association Clinical Pharmacology Committee and Heart Failure and Transplantation Committee of the Council on Clinical Cardiology; Council on Basic Cardiovascular Sciences; Council on Cardiovascular and Stroke Nursing; Council on Epidemiology and Prevention; Council on Lifestyle and Cardiometabolic Health; and Council on Quality of Care and Outcomes Research, 5 August 2020, Circulation.
Co-authors are Larry A. Allen, M.D., M.H.S., FAHA, (vice chair); Robert A. Kloner, M.D., Ph.D.; Colin R. Carriker, Ph.D.; Catherine Martel, Ph.D.; Alanna A. Morris, M.D., M.Sc., FAHA; Mariann R. Piano, R.N., Ph.D., FAHA; Jamal S. Rana, M.D., Ph.D.; Jorge F. Saucedo, M.D., FAHA. Author disclosures are in the manuscript.
A new set of images captured this spring by the Colour and Stereo Surface Imaging System (CaSSIS) on the ESA-Roscosmos ExoMars Trace Gas Orbiter shows a series of interesting geological features on the surface of Mars, captured just as the planet passed its spring equinox.
Dune fields in the Green Crater of Mars
The image above, taken on April 27, 2020 and centered at 52.3°S, 351.8°E, shows part of an impact crater located inside the larger Green Crater in the Argyre quadrangle in the southern hemisphere of Mars.
The image reveals an almost black dune field on the right surrounded by red soils, partially covered with bright white ice. Gullies, also partially covered with ice, are visible in the crater wall in the center of the image. Scientists are currently investigating the relationship between this seasonal ice and the presence of the gullies. The image was taken just after the spring equinox in the southern hemisphere of Mars, when the southernmost part of the crater (to the right) was almost completely free of ice while the northern part (center) was still partially covered. The southern crater wall has had a longer exposure to the Sun (like on Earth, equator-facing slopes receive more sunlight), so the ice in this area has receded faster.
Leaf-like structures in Antoniadi impact crater
This image, captured on March 25, 2020, shows the bottom of the 400 km in diameter Antoniadi impact crater, which is located in the northern hemisphere of Mars in the Syrtis Major Planum region. The blue color of the image, centered at 21.0°N, 61.2°E, does not represent the real color of the crater floor but highlights the diversity of the rock composition inside this impact crater.
In the center of the image are dendritic structures that look like the veins on oak leaves. These structures, evidence of ancient river networks in this region, protrude from the surface, unlike channels, which are usually sunken in the surface. This is because the channels were filled with harder material – possibly lava – and over time the softer rocks surrounding these branching channels have been eroded, leaving an inverted imprint of this ancient river system.
Argyre impact basin after the spring equinox
This image of the Argyre impact basin in the southern highlands of Mars was taken on April 28, 2020, just as Mars had passed its southern hemisphere spring equinox. The seasonal ice in the 800km-long impact basin is visibly receding while the ridge on the right side of the image is still covered with frost. The image is centered at 57.5°S, 310.2°E. The frost-covered ridge is facing the pole, therefore receiving less solar radiation than the neighboring equator-facing slope. On Mars, incoming solar radiation transforms the ice into water vapour directly without melting it first into water in a process called sublimation. Since the north-facing slope (on the left) has had a longer exposure to solar radiation, its ice has sublimated more quickly.
Rock composition in Ius Chasma canyon
The image taken on May 5, 2020 shows a part of the floor of the Ius Chasma canyon, part of the Valles Marines system of canyons that stretches nearly a quarter of the circumference of Mars south of the planet’s equator. The Ius Chasma canyon, which can be seen in the image rising up to a ridge on the right side, is about 1000 km long and up to 8 km deep, which makes it more than twice as long and four times as deep as the famous Grand Canyon in the US state of Arizona. The center of this image is located at 8.8°S, 282.5°E.
The beautiful color variations across the floor of Ius Chasma are caused by changes in rock composition. Scientists theorize that the light rocks are salts left behind after an ancient lake evaporated. The information about the rock’s composition is useful to scientists as it allows them to retrace the formation history of the canyon.
Dinosaur Diagnosed With Malignant Cancer for the First Time – Cancerous Bone From 77 Million Years Ago
Royal Ontario Museum and McMaster University researchers diagnose osteosarcoma in a Centrosaurus apertus.
A collaboration led by the Royal Ontario Museum (ROM) and McMaster University has led to the discovery and diagnosis of an aggressive malignant bone cancer — an osteosarcoma — for the first time ever in a dinosaur. No malignant cancers (tumors that can spread throughout the body and have severe health implications) have ever been documented in dinosaurs previously. The paper was published on August 3rd in the prestigious medical journal The Lancet Oncology.
The cancerous bone in question is the fibula (lower leg bone) from Centrosaurus apertus, a horned dinosaur that lived 76 to 77 million years ago. Originally discovered in Dinosaur Provincial Park in Alberta in 1989, the badly malformed end of the fossil was originally thought to represent a healing fracture. Noting the unusual properties of the bone on a trip to the Royal Tyrrell Museum in 2017, Dr. David Evans, James and Louise Temerty Endowed Chair of Vertebrate Palaeontology from the ROM, and Drs. Mark Crowther, Professor of Pathology and Molecular Medicine, and Snezana Popovic, an histopathologist, both at McMaster University, decided to investigate it further using modern medical techniques. They assembled a team of multidisciplinary specialists and medical professionals from fields including pathology, radiology, orthopedic surgery, and palaeopathology. The team re-evaluated the bone and approached the diagnosis similarly to how it would be approached for the diagnosis of an unknown tumor in a human patient.
“Diagnosis of aggressive cancer like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to properly identify,” says Crowther, who is also a Royal Patrons Circle donor and volunteer at the ROM. “Here, we show the unmistakable signature of advanced bone cancer in 76-million-year-old horned dinosaur — the first of its kind. It’s very exciting.”
After carefully examining, documenting, and casting the bone, the team performed high-resolution computed tomography (CT) scans. They then thin-sectioned the fossil bone and examined it under a microscope to assess it at the bone-cellular level. Powerful three-dimensional CT reconstruction tools were used to visualize the progression of the cancer through the bone. Using this rigorous process, the investigators reached a diagnosis of osteosarcoma.
To confirm this diagnosis, they then compared the fossil to a normal fibula from a dinosaur of the same species, as well as to a human fibula with a confirmed case of osteosarcoma. The fossil specimen is from an adult dinosaur with an advanced stage of cancer that may have invaded other body systems. Yet it was found in a massive bonebed, suggesting it died as part of a large herd of Centrosaurus struck down by a flood.
“The shin bone shows aggressive cancer at an advanced stage. The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of the time,” says Evans, an expert on these horned dinosaurs. “The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease.”
Osteosarcoma is a bone cancer that usually occurs in the second or third decade of life. It is an overgrowth of disorganized bone that spreads rapidly both through the bone in which it originates and to other organs, including most commonly, the lung. It is the same type of cancer that afflicted Canadian athlete Terry Fox and led to the partial amputation of his right leg prior to Fox’s heroic Marathon of Hope in 1980.
“It is both fascinating and inspiring to see a similar multidisciplinary effort that we use in diagnosing and treating osteosarcoma in our patients leading to the first diagnosis of osteosarcoma in a dinosaur,” says Seper Ekhtiari, an Orthopaedic Surgery Resident at McMaster University. “This discovery reminds us of the common biological links throughout the animal kingdom and reinforces the theory that osteosarcoma tends to affect bones when and where they are growing most rapidly.”
This study aims to establish a new standard for the diagnosis of unclear diseases in dinosaur fossils and opens the door to more precise and more certain diagnoses. Establishing links between human disease and the diseases of the past will help scientists to gain a better understanding of the evolution and genetics of various diseases. Evidence of many other diseases that we share with dinosaurs and other extinct animals may yet be sitting in museum collections in need of re-examination using modern analytical techniques.
Reference: “First case of osteosarcoma in a dinosaur: a multimodal diagnosis” by Seper Ekhtiari, Kentaro Chiba, Snezana Popovic, Rhianne Crowther, Gregory Wohl, Andy Kin On Wong, Darren H Tanke, Danielle M Dufault, Olivia D Geen, Naveen Parasu, Mark A Crowther and David C Evans, August 2020, The Lancet Oncology.
Funding for David Evans was provided by an NSERC Discovery Grant, and research computers for 3D visualization were generously supported by The Dorothy Strelsin Foundation.