Electrical dipole activity detected in a quantum material unlike any other tested

Date:
June 11, 2018

Source:
Johns Hopkins University

Summary:
A theorized but never-before detected property of quantum matter has now been spotted in the lab.

 

The structure of the crystal that was studied in the research; an individual molecule is highlighted in red.
Credit: Institute for Quantum Matter/JHU

 

 

A theorized but never-before detected property of quantum matter has now been spotted in the lab, a team of scientists reports.

The team proved that a particular quantum material can demonstrate electrical dipole fluctuations — irregular oscillations of tiny charged poles on the material — even in extremely cold conditions, in the neighborhood of minus 450 degrees Fahrenheit.

The material, first synthesized 20 years ago, is called k-(BEDT-TTF)2Hg(SCN)2 Br. It is derived from organic compounds, but behaves like a metal.

“What we found with this particular quantum material is that, even at super-cold temperatures, electrical dipoles are still present and fluctuate according to the laws of quantum mechanics,” said Natalia Drichko, associate research professor in physics at the Johns Hopkins University.

“Usually, we think of quantum mechanics as a theory of small things, like atoms, but here we observe that the whole crystal is behaving quantum-mechanically,” said Drichko, senior author of a paper on the research published in the journal Science.

Classical physics describes most of the behavior of physical objects we see and experience in everyday life. In classical physics, objects freeze at extremely low temperatures, Drichko said. In quantum physics — science that has grown up primarily to describe the behavior of matter and energy at the atomic level and smaller — there is motion even at those frigid temperatures, Drichko said.

“That’s one of the major differences between classical and quantum physics that condensed matter physicists are exploring,” she said.

An electrical dipole is a pair of equal but oppositely charged poles separated by some distance. Such dipoles can, for instance, allow a hair to “stick” to a comb through the exchange of static electricity: Tiny dipoles form on the edge of the comb and the edge of the hair.

Drichko’s research team observed the new extreme-low-temperature electrical state of the quantum matter in Drichko’s Raman spectroscopy lab, where the key work was done by graduate student Nora Hassan. Team members shined focused light on a small crystal of the material. Employing techniques from other disciplines, including chemistry and biology, they found proof of the dipole fluctuations.

The study was possible because of the team’s home-built, custom-engineered spectrometer, which increased the sensitivity of the measurements 100 times.

The unique quantum effect the team found could potentially be used in quantum computing, a type of computing in which information is captured and stored in ways that take advantage of the quantum states of matter.

Story Source:

Materials provided by Johns Hopkins UniversityNote: Content may be edited for style and length.


Journal Reference:

  1. Nora Hassan, Streit Cunningham, Martin Mourigal, Elena I. Zhilyaeva, Svetlana A. Torunova, Rimma N. Lyubovskaya, John A. Schlueter, Natalia Drichko. Evidence for a quantum dipole liquid state in an organic quasi–two-dimensional materialScience, 2018; 360 (6393): 1101 DOI: 10.1126/science.aan6286

 

Source: Johns Hopkins University. “Evidence for a new property of quantum matter revealed: Electrical dipole activity detected in a quantum material unlike any other tested.” ScienceDaily. ScienceDaily, 11 June 2018. <www.sciencedaily.com/releases/2018/06/180611172416.htm>.

Filed Under News | Leave a Comment 

Date:
June 11, 2018

Source:
DOE/Oak Ridge National Laboratory

Summary:
Scientists have developed a metal-organic framework material with a selective, fully reversible and repeatable capability to remove atmospheric nitrogen dioxide gas in ambient conditions. The discovery, confirmed by researchers using neutron scattering, could facilitate air filtration technologies that capture and convert targeted gases, including carbon dioxide and other greenhouse gases, for long-term sequestration to mitigate air pollution and global warming.

 

Illustration of a nitrogen dioxide molecule (depicted in red and gold) confined within a nano-size pore of an MFM-300(Al) metal-organic framework material as characterized using neutron scattering at Oak Ridge National Laboratory.
Credit: ORNL/Jill Hemman

 

 

Led by the University of Manchester, an international team of scientists has developed a metal-organic framework material (MOF) that exhibits a selective, fully reversible and repeatable capability to remove nitrogen dioxide gas from the atmosphere in ambient conditions. This discovery, confirmed by researchers using neutron scattering at the Department of Energy’s Oak Ridge National Laboratory, could lead to air filtration technologies that cost-effectively capture and convert large quantities of targeted gases, including carbon dioxide and other greenhouse gases, to facilitate their long-term sequestration to help mitigate air pollution and global warming.

As reported in Nature Materials, the material denoted as MFM-300(Al) exhibited the first reversible, selective capture of nitrogen dioxide at ambient pressures and temperatures — at low concentrations — in the presence of moisture, sulfur dioxide and carbon dioxide. Despite the highly reactive nature of nitrogen dioxide, the MFM-300(Al) material proved extremely robust, demonstrating the capability to be fully regenerated, or degassed, multiple times without loss of crystallinity or porosity.

“This material is the first example of a metal-organic framework that exhibits a highly selective and fully reversible capability for repeated separation of nitrogen dioxide from the air, even in presence of water,” said Sihai Yang, one of the study’s lead authors and a lecturer in inorganic chemistry at Manchester’s School of Chemistry.

Professor Martin Schröder, another lead author from Manchester Chemistry, commented, “Other studies of different porous materials often found performance was degraded in subsequent cycles by the nitrogen dioxide, or that the regeneration process was too difficult and costly.”

As part of the research, the scientists used neutron scattering techniques at the Department of Energy’s Oak Ridge National Laboratory to confirm and precisely characterize how MFM-300(Al) captures nitrogen dioxide molecules.

“Neutrons can easily penetrate dense materials and they are sensitive to lighter elements, such as the hydrogen atoms inside the MFM, which enabled us to observe how the nitrogen dioxide molecules are confined within the nano-size pores,” said Timmy Ramirez-Cuesta, a co-author and coordinator for the chemistry and catalysis initiative at ORNL’s Neutron Sciences Directorate. “We benefitted from the extremely high sensitivity and quantitative data provided by the VISION vibrational spectroscopy instrument on ORNL’s 16-B beamline at the Spallation Neutron Source, which uses neutrons instead of photons to probe molecular vibrations.”

The ability to directly observe how and where MFM-300(Al) traps nitrogen dioxide is helping the researchers validate a computer model of the MOF gas separation process, which could help identify how to produce and tailor other materials to capture a variety of different gases.

“Computer modeling and simulation played critical roles in interpreting the neutron scattering data by helping us connect subtle changes in the vibrational spectra to interactions between the MFM-300 and trapped molecules,” said Yongqiang Cheng, an ORNL neutron scattering scientist and co-author. “Our goal is to integrate the model with experimental techniques to deliver results that are otherwise difficult to achieve.”

Capturing greenhouse and toxic gases from the atmosphere has long been a challenge, because of their relatively low concentrations and the presence of moisture in the air, which can negatively affect separating targeted gas molecules from other gases. Another challenge has been finding a practical way to release a captured gas for long-term sequestration, such as in underground depleted oil reservoirs or saline-filled rock formations. MOFs offer solutions to many of these challenges, which is why they are the subject of recent scientific investigations.

The research team involved scientists from institutions in five nations, including the University of Nottingham, University of Newcastle upon Tyne, University of Nottingham Ningbo China, Peking University, the International Tomography Center SB RAS, Novosibirsk State University, and the European Synchrotron Radiation Facility in Grenoble.

Story Source:

Materials provided by DOE/Oak Ridge National LaboratoryNote: Content may be edited for style and length.


Journal Reference:

  1. Xue Han, Harry G. W. Godfrey, Lydia Briggs, Andrew J. Davies, Yongqiang Cheng, Luke L. Daemen, Alena M. Sheveleva, Floriana Tuna, Eric J. L. McInnes, Junliang Sun, Christina Drathen, Michael W. George, Anibal J. Ramirez-Cuesta, K. Mark Thomas, Sihai Yang, Martin Schröder. Reversible adsorption of nitrogen dioxide within a robust porous metal–organic frameworkNature Materials, 2018; DOI: 10.1038/s41563-018-0104-7

 

Source: DOE/Oak Ridge National Laboratory. “MOF material offers selective, reversible and repeatable capture of toxic atmospheric gas.” ScienceDaily. ScienceDaily, 11 June 2018. <www.sciencedaily.com/releases/2018/06/180611133832.htm>.

Filed Under News | Leave a Comment 

Date:
June 8, 2018

Source:
University of Miami

Summary:
A neurorehabilitation expert who helps modern patients recover from brain surgery, chronicles the remarkable skill of ancient Peru’s cranial surgeons.

 

More ancient skulls bearing evidence of trepanation — a telltale hole surgically cut into the cranium — have been found in Peru than the combined number found in the rest of the world.
Credit: University of Miami

 

 

Even with a highly skilled neurosurgeon, the most effective anesthesia, and all the other advances of modern medicine, most of us would cringe at the thought of undergoing cranial surgery today.

After all, who needs a hole in the head? Yet for thousands of years, trepanation — the act of scraping, cutting, or drilling an opening into the cranium — was practiced around the world, primarily to treat head trauma, but possibly to quell headaches, seizures and mental illnesses, or even to expel perceived demons.

But, according to a new study led by the University of Miami Miller School of Medicine’s David S. Kushner, M.D., clinical professor of physical medicine and rehabilitation, trepanation was so expertly practiced in ancient Peru that the survival rate for the procedure during the Incan Empire was about twice that of the American Civil War — when, more three centuries later, soldiers were trepanned presumably by better trained, educated and equipped surgeons.

“There are still many unknowns about the procedure and the individuals on whom trepanation was performed, but the outcomes during the Civil War were dismal compared to Incan times,” said Kushner, a neurologist who has helped scores of patients recover from modern-day traumatic brain injuries and cranial surgeries. “In Incan times, the mortality rate was between 17 and 25 percent, and during the Civil War, it was between 46 and 56 percent. That’s a big difference. The question is how did the ancient Peruvian surgeons have outcomes that far surpassed those of surgeons during the American Civil War?”

In their study published in the June issue of World Neurosurgery, “Trepanation Procedures/Outcomes: Comparison of Prehistoric Peru with Other Ancient, Medieval, and American Civil War Cranial Surgery,” Kushner and his co-authors — biological anthropologists John W. Verano, a world authority on Peruvian trepanation at Tulane University, and his former graduate student, Anne R. Titelbaum, now of the University of Arizona College of Medicine — can only speculate on the answer.

But hygiene, or more accurately the lack of it during the Civil War, may have contributed to the higher mortality rates in the later time period. According to the study, which relied on Verano’s extensive field research on trepanation over a nearly 2,000-year period in Peru and a review of the scientific literature about trepanation around the world, Civil War surgeons often used unsterilized medical tools and their bare fingers to probe open cranial wounds or break up blood clots.

“If there was an opening in the skull they would poke a finger into the wound and feel around, exploring for clots and bone fragments,” Kushner said, adding that nearly every Civil War soldier with a gunshot wound subsequently suffered from infection. “We do not know how the ancient Peruvians prevented infection, but it seems that they did a good job of it. Neither do we know what they used as anesthesia, but since there were so many (cranial surgeries) they must have used something — possibly coca leaves. Maybe there was something else, maybe a fermented beverage. There are no written records, so we just don’t know.”

Whatever their methods, ancient Peruvians had plenty of practice. More than 800 prehistoric skulls with evidence of trepanation — at least one but as many as seven telltale holes — have been found in the coastal regions and the Andean highlands of Peru, the earliest dating back to about 400 B.C. That’s more than the combined total number of prehistoric trepanned skulls found in the rest of the world. Which is why Verano devoted an entire book, Holes in the Head — The Art and Archeology of Trepanation in Ancient Peru, to the 800-plus skulls, most of which were collected from burial caves and archaeological digs in the late 1800s and early 1900s and reside in museums and private collections today.

It’s also why Kushner, a medical history buff and Tulane alumnus, jumped at the chance to join Titelbaum in co-authoring one of the book’s chapters, “Trepanation from the Perspective of Modern Neurosurgery,” and continues to research the subject.

Published in 2016, the book analyzes the techniques and survival rates of trepanation in Peru through the demise of the Incan Empire in the early 1500s. The researchers gauged survival by classifying the extent of bone remodeling around the trepanned holes, which indicates healing. If there was no evidence of healing the researchers assumed the patient died during or within days of the surgery. If the margins of the trepanation openings showed extensive remodeling, they considered the operation successful and the patient long-lived.

Those classifications, Kushner, Verano and Titelbaum reported in the World Neurosurgery paper, show how ancient Peruvians significantly refined their trepanation techniques over the centuries. They learned, for example, not to perforate the protective membrane surrounding the brain — a guideline Hippocrates codified in ancient Greece at about the same time, 5th century, B.C., that trepanning is thought to have begun in ancient Peru.

The long-term survival rates from such “shallow surgeries” in Peru during those early years, from about 400 to 200 B.C., proved to be worse than those in the Civil War, when about half the patients died. But, from 1000 to 1400 A.D., survival rates improved dramatically, to as high as 91 percent in some samples, to an average of 75 to 83 percent during the Incan period, the study showed.

“Over time, from the earliest to the latest, they learned which techniques were better, and less likely to perforate the dura,” said Kushner, who has written extensively about modern-day neurosurgical outcomes. “They seemed to understand head anatomy and purposefully avoided the areas where there would be more bleeding. They also realized that larger-sized trepanations were less likely to be as successful as smaller ones. Physical evidence definitely shows that these ancient surgeons refined the procedure over time. Their success is truly remarkable.”

Almost as remarkable is how, by the end of World War I, cranial surgery evolved into the distinct profession of neurosurgery, which continues to improve our understanding of brain anatomy, physiology and pathology. As Kushner notes, today’s neurosurgeons regularly cut into the brain to remove tumors and blood clots, reduce intracranial pressure from massive strokes and trauma, repair vascular and structural anomalies and treat a myriad of other complex problems — with great success.

“Today, neurosurgical mortality rates are very, very low; there is always a risk but the likelihood of a good outcome is very high,” he said. “And just like in ancient Peru, we continue to advance our neurosurgical techniques, our skills, our tools, and our knowledge.”

Story Source:

Materials provided by University of MiamiNote: Content may be edited for style and length.


Journal Reference:

  1. David S. Kushner, John W. Verano, Anne R. Titelbaum. Trepanation Procedures/Outcomes: Comparison of Prehistoric Peru with Other Ancient, Medieval, and American Civil War Cranial SurgeryWorld Neurosurgery, 2018; 114: 245 DOI: 10.1016/j.wneu.2018.03.143

Source: University of Miami. “Remarkable skill of ancient Peru’s cranial surgeons.” ScienceDaily. ScienceDaily, 8 June 2018. .

Filed Under News | Leave a Comment 

Date:
June 7, 2018

Source:
Instituto de Astrofísica de Canarias (IAC)

Summary:
A team of researchers suggests that if we could travel at the speed of light it would take us 200,000 years to cross the disc of our Galaxy.

 

The coloured region is the previously known Galactic disk. The present work has extended its limits much farther away: there is a probability 99.7 percent or 95.4 percent respectively that there are disk stars in the regions outside the dashed/dotted circles. Yellow dot is the position of the Sun. Background Milky Way image from ‘A Roadmap to the Milky Way’.
Credit: R. Hurt, SSC-Caltech, NASA/JPL-Caltech

 

 

Spiral galaxies such as the Milky Way have discs which are really thin, in which the major fraction of their stars are found. These discs are limited in size, so that beyond certain radius there are very few stars left.

In our Galaxy we were not aware that there are stars in the disc at distances from the centre more than twice that of the Sun. This means that our own star was apparently orbiting at about half the galactic radius. However now we know that there are stars quite a bit further out, at more than three times this distance, and it is probable that some stars are at more than four times the distance of the Sun from the Galactic centre.

“The disc of our Galaxy is huge, around 200 thousand light years in diameter” says Martín López-Corredoira, a researcher at the IAC and the first author of the article recently published in the journal Astronomy & Astrophysics and whose authors come from both the IAC and the NAOC.

In broad terms we can think of galaxies like the Milky Way as being composed of a rotating disc, which includes spiral arms, and a halo, spherical in shape, which surrounds it. This piece of research has compared the abundances of metals (heavy elements) in the stars of the Galactic plane with those of the halo, to find that there is a mixture of disc and halo stars out to the large distances indicated.

The researchers came to these conclusions after make a statistical analysis of survey date from APOGEE and LAMOST, two projects which obtain spectra of stars to extract information about their velocities and their chemical compositions. “Using the metallicities of the stars in the catalogues from the high quality spectral atlases of APOGEE and LAMOST, and with the distances at which the objects are situated, we have shown that there is an appreciable fraction of stars with higher metallicity, characteristic of disc stars, further out than the previously assumed limit on the radius of the Galaxy disc” explains Carlos Allende, a researcher at the IAC and a co-author of this publication.

Francisco Garzón, an IAC researcher who is another of the authors of the article explains that “We have not used models, which sometimes give us only the answers for which they were designed, but we have employed only the statistics of a large number of objects. The results are therefore free from a priori assumptions, apart from a few basic and well established ones.”

Story Source:

Materials provided by Instituto de Astrofísica de Canarias (IAC)Note: Content may be edited for style and length.


Journal Reference:

  1. M. López-Corredoira, C. Allende Prieto, F. Garzón, H. Wang, C. Liu, L. Deng. Disk stars in the Milky Way detected beyond 25 kpc from its centerAstronomy & Astrophysics, 2018; 612: L8 DOI: 10.1051/0004-6361/201832880

 

Source: Instituto de Astrofísica de Canarias (IAC). “The disc of the Milky Way is bigger than we thought.” ScienceDaily. ScienceDaily, 7 June 2018. <www.sciencedaily.com/releases/2018/06/180607112746.htm>.

Filed Under News | Leave a Comment 

Date:
June 6, 2018

Source:
University of Colorado at Boulder

Summary:
Rats immunized weekly for three weeks with beneficial bacteria showed increased levels of anti-inflammatory proteins in the brain, more resilience to the physical effects of stress, and less anxiety-like behavior. If replicated in humans, researchers say the findings could lead to novel microbiome-based immunizations for mood disorders like anxiety and PTSD.

 

Immunization with this friendly bacteria has been found to create a more stress-resilient environment in the brain.
Credit: CU Boulder

 

 

Immunization with beneficial bacteria can have long-lasting anti-inflammatory effects on the brain, making it more resilient to the physical and behavioral effects of stress, according to new research by University of Colorado Boulder scientists.

The findings, if replicated in clinical trials could ultimately lead to new probiotic-based immunizations to protect against posttraumatic stress disorder (PTSD) and anxiety or new treatments for depression, the authors say.

“We found that in rodents this particular bacterium, Mycobacterium vaccae, actually shifts the environment in the brain toward an anti-inflammatory state,” said lead author Matthew Frank, a senior research associate in the Department of Psychology and Neuroscience. “If you could do that in people, it could have broad implications for a number of neuroinflammatory diseases.”

Anxiety, PTSD and other stress-related mental disorders impact as many as one in four people in their lifetime. Mounting research suggests that stress-induced brain inflammation can boost risk of such disorders, in part by impacting mood-influencing neurotransmitters like norepinephrine or dopamine.

“There is a robust literature that shows if you induce an inflammatory immune response in people, they quickly show signs of depression and anxiety,” said Frank. “Just think about how you feel when you get the flu.”

Research also suggests that trauma, illness or surgery can sensitize certain regions of the brain, setting up a hair-trigger inflammatory response to subsequent stressors which can lead to mood disorders and cognitive decline.

“We found that Mycobacterium vaccae blocked those sensitizing effects of stress too, creating a lasting stress-resilient phenotype in the brain,” Frank said.

A previous CU Boulder study, published in the Proceedings of the National Academy of Sciences (PNAS), found that mice injected with a heat-killed preparation of M. vaccae and then placed with a larger aggressive male for 19 days exhibited less anxiety-like behavior and were less likely to suffer colitis or inflammation in their peripheral tissues.

For the new study, published this week in the journal Brain, Behavior and Immunity, Frank and senior author Christopher Lowry, an associate professor in integrative physiology, set out to find out what exactly M. vaccae does in the brain.

Male rats injected with the bacterium three times, one week apart, had significantly higher levels of the anti-inflammatory protein interleukin-4 in the hippocampus — a brain region responsible for modulating cognitive function, anxiety and fear — eight days after the final injection.

After exposure to a stressor, the immunized animals also showed lower levels of a stress-induced protein, or alarmin, called HMGB1, believed to play a role in sensitizing the brain to inflammation, and higher expression of CD200R1, a receptor key for keeping glial cells (the brain’s immune cells) in an anti-inflammatory state.

The immunized rats, as in the first study, exhibited less anxious behavior after stress.

“If you look at the field of probiotics generally, they have been shown to have strong effects in the domains of cognitive function, anxiety and fear,” said Lowry. “This paper helps make sense of that by suggesting that these beneficial microbes, or signals derived from these microbes, somehow make their way to the hippocampus, inducing an anti-inflammatory state.”

Lowry envisions a day when M. vaccae (which was first isolated from the mud on the shores of Lake Kyoga in Uganda) could be administered to people at high risk of PTSD — such as soldiers preparing to be deployed or emergency room workers — to buffer the effects of stress on the brain and body. It could also possibly be used to prevent sepsis-induced cognitive impairment.

Meanwhile, Lowry is working with researchers at University of Colorado Denver on a study exploring whether veterans with PTSD can benefit from an oral probiotic consisting of a different bacterial strain, Lactobacillus reuteri.

“More research is necessary, but it’s possible that other strains of beneficial bacteria or probiotics may have a similar effect on the brain,” he said.

Story Source:

Materials provided by University of Colorado at BoulderNote: Content may be edited for style and length.


Journal Reference:

  1. Matthew G. Frank, Laura K. Fonken, Samuel D. Dolzani, Jessica L. Annis, Philip H. Siebler, Dominic Schmidt, Linda R. Watkins, Steven F. Maier, Christopher A. Lowry. Immunization with Mycobacterium vaccae induces an anti-inflammatory milieu in the CNS: Attenuation of stress-induced microglial priming, alarmins and anxiety-like behaviorBrain, Behavior, and Immunity, 2018; DOI: 10.1016/j.bbi.2018.05.020

 

Source: University of Colorado at Boulder. “Immunization with beneficial bacteria makes brain more stress resilient.” ScienceDaily. ScienceDaily, 6 June 2018. <www.sciencedaily.com/releases/2018/06/180606170148.htm>.

Filed Under News | Leave a Comment 

Scientists studying ancient rocks say crust could have formed when Earth was just 350 million years old

Date:
June 5, 2018

Source:
University of Chicago

Summary:
The early Earth might have been habitable much earlier than thought, according to new research.

 

Scientists studied 3.9-billion-year-old rocks from Nuvvuagittuq, Canada, and found evidence for an earlier formation of the crust.
Credit: Elizabeth Bell

 

 

The early Earth might have been habitable much earlier than thought, according to new research from a group led by University of Chicago scientists.

Counting strontium atoms in rocks from northern Canada, they found evidence that the Earth’s continental crust could have formed hundreds of millions of years earlier than previously thought. Continental crust is richer in essential minerals than younger volcanic rock, which would have made it significantly friendlier to supporting life.

“Our evidence, which squares with emerging evidence including rocks in western Australia, suggests that the early Earth was capable of forming continental crust within 350 million years of the formation of the solar system,” said Patrick Boehnke, the T.C. Chamberlin Postdoctoral Fellow in the Department of Geophysical Sciences and the first author on the paper. “This alters the classic view, that the crust was hot, dry and hellish for more than half a billion years after it formed.”

One of the open questions in geology is how and when some of the crust — originally all younger volcanic rock — changed into the continental crust we know and love, which is lighter and richer in silica. This task is made harder because the evidence keeps getting melted and reformed over millions of years. One of the few places on Earth where you can find bits of crust from the very earliest epochs of Earth is in tiny flecks of apatite imbedded in younger rocks.

Luckily for scientists, some of these “younger” minerals (still about 3.9 billion years old) are zircons — very hard, weather-resistant minerals somewhat similar to diamonds. “Zircons are a geologist’s favorite because these are the only record of the first three to four hundred million years of Earth. Diamonds aren’t forever — zircons are,” Boehnke said.

Plus, the zircons themselves can be dated. “They’re like labeled time capsules,” said Prof. Andrew Davis, chair of the Department of Geophysical Sciences and a coauthor on the study.

Scientists usually look at the different variants of elements, called isotopes, to tell a story about these rocks. They wanted to use strontium, which offers clues to how much silica was around at the time it formed. The only problem is that these flecks are absolutely tiny — about five microns across, the diameter of a strand of spider silk — and you have to count the strontium atoms one by one.

This was a task for a unique instrument that came online last year: the CHicago Instrument for Laser Ionization, or CHILI. This detector uses lasers that can be tuned to selectively pick out and ionize strontium. When they used CHILI to count strontium isotopes in rocks from Nuvvuagittuq, Canada, they found the isotope ratio suggested plenty of silica was present when it formed.

This is important because the makeup of the crust directly affects the atmosphere, the composition of seawater, and nutrients available to any budding life hoping to thrive on planet Earth. It also may imply there were fewer meteorites than thought pummeling the Earth at this time, which would have made it hard for continental crust to form.

“Having continental crust that early changes the picture of early Earth in a number of ways,” said Davis, who is also a professor with the Enrico Fermi Institute. “Now we need a way for the geologic processes that make the continents to happen much faster; you probably need water and magma that’s about 600 degrees Fahrenheit less hot.”

The study is also confluent with a recent paper by Davis and Boehnke’s colleague Nicolas Dauphas, which found evidence for rain falling on continents 2.5 billion years ago, earlier than previously thought.

Story Source:

Materials provided by University of Chicago. Original written by Louise Lerner. Note: Content may be edited for style and length.


Journal Reference:

  1. Patrick Boehnke, Elizabeth A. Bell, Thomas Stephan, Reto Trappitsch, C. Brenhin Keller, Olivia S. Pardo, Andrew M. Davis, T. Mark Harrison, Michael J. Pellin. Potassic, high-silica Hadean crustProceedings of the National Academy of Sciences, 2018; 201720880 DOI: 10.1073/pnas.1720880115

 

Source: University of Chicago. “Earth could have supported continental crust, life earlier than thought: Scientists studying ancient rocks say crust could have formed when Earth was just 350 million years old.” ScienceDaily. ScienceDaily, 5 June 2018. <www.sciencedaily.com/releases/2018/06/180605154122.htm>.

Filed Under News | Leave a Comment 

Date:
June 4, 2018

Source:
University of Wisconsin-Madison

Summary:
A new study that reconstructs the deep history of our planet’s relationship to the moon shows that 1.4 billion years ago, a day on Earth lasted just over 18 hours. This is at least in part because the moon was closer and changed the way the Earth spun around its axis.

 

Image of Earth taken by the Apollo 8 astronauts on Dec. 22, 1968 as they became the first humans to circumnavigate the moon.
Credit: Courtesy of NASA

 

 

For anyone who has ever wished there were more hours in the day, geoscientists have some good news: Days on Earth are getting longer.

A new study that reconstructs the deep history of our planet’s relationship to the moon shows that 1.4 billion years ago, a day on Earth lasted just over 18 hours. This is at least in part because the moon was closer and changed the way Earth spun around its axis.

“As the moon moves away, the Earth is like a spinning figure skater who slows down as they stretch their arms out,” explains Stephen Meyers, professor of geoscience at the University of Wisconsin-Madison and co-author of the study published this week [June 4, 2018] in the Proceedings of the National Academy of Sciences.

It describes a tool, a statistical method, that links astronomical theory with geological observation (called astrochronology) to look back on Earth’s geologic past, reconstruct the history of the solar system and understand ancient climate change as captured in the rock record.

“One of our ambitions was to use astrochronology to tell time in the most distant past, to develop very ancient geological time scales,” Meyers says. “We want to be able to study rocks that are billions of years old in a way that is comparable to how we study modern geologic processes.”

Earth’s movement in space is influenced by the other astronomical bodies that exert force on it, like other planets and the moon. This helps determine variations in Earth’s rotation around and wobble on its axis, and in the orbit Earth traces around the sun.

These variations are collectively known as Milankovitch cycles and they determine where sunlight is distributed on Earth, which also means they determine Earth’s climate rhythms. Scientists like Meyers have observed this climate rhythm in the rock record, spanning hundreds of millions of years.

But going back further, on the scale of billions of years, has proved challenging because typical geologic means, like radioisotope dating, do not provide the precision needed to identify the cycles. It’s also complicated by lack of knowledge of the history of the moon, and by what is known as solar system chaos, a theory posed by Parisian astronomer Jacques Laskar in 1989.

The solar system has many moving parts, including the other planets orbiting the sun. Small, initial variations in these moving parts can propagate into big changes millions of years later; this is solar system chaos, and trying to account for it can be like trying to trace the butterfly effect in reverse.

Last year, Meyers and colleagues cracked the code on the chaotic solar system in a study of sediments from a 90 million-year-old rock formation that captured Earth’s climate cycles. Still, the further back in the rock record he and others have tried to go, the less reliable their conclusions.

For instance, the moon is currently moving away from Earth at a rate of 3.82 centimeters per year. Using this present day rate, scientists extrapolating back through time calculated that “beyond about 1.5 billion years ago, the moon would have been close enough that its gravitational interactions with the Earth would have ripped the moon apart,” Meyers explains. Yet, we know the moon is 4.5 billion years old.

So, Meyers sought a way to better account for just what our planetary neighbors were doing billions of years ago in order to understand the effect they had on Earth and its Milankovitch cycles. This was the problem he brought with him to a talk he gave at Columbia University’s Lamont-Doherty Earth Observatory while on sabbatical in 2016.

In the audience that day was Alberto Malinverno, Lamont Research Professor at Columbia. “I was sitting there when I said to myself, ‘I think I know how to do it! Let’s get together!'” says Malinverno, the other study co-author. “It was exciting because, in a way, you dream of this all the time; I was a solution looking for a problem.”

The two teamed up to combine a statistical method that Meyers developed in 2015 to deal with uncertainty across time — called TimeOpt — with astronomical theory, geologic data and a sophisticated statistical approach called Bayesian inversion that allows the researchers to get a better handle on the uncertainty of a study system.

They then tested the approach, which they call TimeOptMCMC, on two stratigraphic rock layers: the 1.4 billion-year-old Xiamaling Formation from Northern China and a 55 million-year-old record from Walvis Ridge, in the southern Atlantic Ocean.

With the approach, they could reliably assess from layers of rock in the geologic record variations in the direction of the axis of rotation of Earth and the shape of its orbit both in more recent time and in deep time, while also addressing uncertainty. They were also able to determine the length of day and the distance between Earth and the moon.

“In the future, we want to expand the work into different intervals of geologic time,” says Malinverno.

The study complements two other recent studies that rely on the rock record and Milankovitch cycles to better understand Earth’s history and behavior.

A research team at Lamont-Doherty used a rock formation in Arizona to confirm the remarkable regularity of Earth’s orbital fluctuations from nearly circular to more elliptical on a 405,000 year cycle. And another team in New Zealand, in collaboration with Meyers, looked at how changes in Earth’s orbit and rotation on its axis have affected cycles of evolution and extinction of marine organisms called graptoloids, going back 450 million years.

“The geologic record is an astronomical observatory for the early solar system,” says Meyers. “We are looking at its pulsing rhythm, preserved in the rock and the history of life.”

The study was funded by the National Science Foundation (EAR-1151438).

Story Source:

Materials provided by University of Wisconsin-Madison. Original written by Kelly April Tyrrell. Note: Content may be edited for style and length.


Journal Reference:

  1. Stephen R. Meyers, Alberto Malinverno. Proterozoic Milankovitch cycles and the history of the solar systemProceedings of the National Academy of Sciences, 2018; 201717689 DOI: 10.1073/pnas.1717689115

 

Source: University of Wisconsin-Madison. “Thank the moon for Earth’s lengthening day.” ScienceDaily. ScienceDaily, 4 June 2018. <www.sciencedaily.com/releases/2018/06/180604151200.htm>.

Filed Under News | Leave a Comment 

2018 DIA Meeting in Boston: We’ll be at the DIA from June 25th to June 27th

 

Let us know if you are attending, and if yes, visit us at Booth 2337. This year we will feature:

 

1. CRO services: Reg Affairs, Clinical Research, Biostats, Data Management and Medical Writing

2. Our paperless clinical trial operation

3. Target e*CRF® fully integrated with Target e*CTR®, our patented web-based direct data entry solution

4. Target eICF® fully integrated with Target e*CRF®

5. A glimpse into our next software version which will be EDC for All

 

For more information about Target Health contact Warren Pearlson (212-681-2100 ext. 165). For additional information about software tools for paperless clinical trials, please also feel free to contact Dr. Jules T. Mitchel. The Target Health software tools are designed to partner with both CROs and Sponsors. Please visit the Target Health Website.

 

Joyce Hays, Founder and Editor in Chief of On Target

Jules Mitchel, Editor

 

Filed Under News, What's New | Leave a Comment 

Cataract Surgery

Capt. Joseph Pasternak, an ophthalmology surgeon at National Naval Medical Center Bethesda, lines up the laser on Marine Corps Lt. Col. Lawrence Ryder’s eye before beginning LASIK VISX surgery. The actual procedure can take only seconds, while most of the patient’s time is spent preparing for the procedure.  Photo credit: U.S. Navy photo by Mass Communication Specialist 1st Class Brien Aho; Public Domain, Wikipedia

 

 

A cataract is an opacification or cloudiness of the eye’s crystalline lens due to aging, disease, or trauma that typically prevents light from forming a clear image on the 1) ___. If visual loss is significant, surgical removal of the lens may be warranted, with lost optical power usually replaced with a plastic intraocular lens (IOL). Owing to the high prevalence of cataracts, cataract extraction is the most common eye surgery. Rest after surgery is recommended. The clouding of the lens leads to a decrease in 2) ___. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause half of all cases of blindness and 33% of visual impairment worldwide. Cataracts are most commonly due to 3) ___ but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol. Either clumps of protein or yellow-brown pigment may be deposited in the lens reducing the transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination. The genetic component is strong in the development of cataracts, most commonly through mechanisms that protect and maintain the lens.

 

Prevention includes wearing sunglasses and not smoking. Early on the symptoms may be improved with 4) ___. If this does not help, surgery to remove the cloudy lens and replace it with an artificial lens is the only effective treatment. Surgery is needed only if the cataracts are causing problems and generally results in an improved quality of life. Cataract surgery is not readily available in many countries, which is especially true for women, those living in rural areas, and those who do not know how to read. About 20 million people are blind due to cataracts. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. 5) ___ from cataracts occurs in about 10 to 40 per 100,000 children in the developing world, and 1 to 4 per 100,000 children in the developed world. Cataracts become more common with age. More than half the people in the United States had cataracts by the age of 80.

 

Blunt trauma causes swelling, thickening, and whitening of the lens fibers. While the swelling normally resolves with time, the white color may remain. In severe blunt trauma, or in injuries that penetrate the eye, the capsule in which the lens sits can be damaged. This damage allows fluid from other parts of the eye to rapidly enter the lens leading to swelling and then whitening, obstructing light from reaching the retina at the back of the eye. Cataracts may develop in 0.7 to 8.0% of cases following electrical injuries. Blunt trauma can also result in star- or petal-shaped cataracts.

 

Femtosecond laser-assisted cataract surgery (FLACS) has gained popularity in recent years with the new technology suggesting potential improvements in clinical and safety outcomes over conventional phacoemulsification cataract surgery (PCS). A decade since the advent of FLACS has given time and experience for laser technology to develop in maturity, and better quality evidence to become available.

 

Just behind the iris and pupil lies the lens, which helps focus light on the back of your eye. Most of the eye is filled with a clear gel called the vitreous. Light projects through your pupil and lens to the back of the eye. The inside lining of the eye is covered by special light-sensing cells that are collectively called the retina. It converts light into electrical impulses. Behind the eye, your optic 6) ___ carries these impulses to the brain. The macula is a small extra-sensitive area in the retina that gives you central vision.

 

In most cases, waiting to have cataract surgery won’t harm your eye, so you have time to consider your options. If your vision is still quite good, you may not need cataract surgery for many years, if ever. Complications after cataract surgery are uncommon, and most can be treated successfully.

 

Undergoing Tests: A week or so before your surgery, a painless ultrasound test is performed to measure the size and shape of the eye. This helps determine the right type of lens implant (intraocular lens, or IOL). The eye surgeon advises the patient to temporarily stop taking any medication that could increase risk of 7) ___ during the procedure. Use eyedrops to reduce infection risk. Antibiotic eyedrops may be prescribed for use one or two days before the surgery.

 

Fast before surgery. You may be instructed not to eat or drink anything 12 hours before the procedure.

 

Prepare for your recovery. Normally you can go home on the same day as your surgery, but you won’t be able to drive, so arrange for a ride home. Also arrange for help around home, if necessary, because your doctor may limit activities, such as bending and lifting, for about a week after your surgery.

 

Nearly everyone who has cataract surgery will be given an 8) ___ lens called an intraocular lens (IOL). These lenses improve your vision by focusing light on the back of your eye. You won’t be able to see or feel the lens. It requires no care and becomes a permanent part of your eye. A variety of IOLs with different features are available. Before surgery, you and your eye doctor will discuss which type of intraocular lens (IOL) might work best for you and your lifestyle. Cost may also be a factor, as insurance companies may not pay for all types of lenses. IOLs are made of plastic, acrylic or silicone. Some IOLs block ultraviolet light. Some IOLs are rigid plastic and implanted through an incision that requires several stitches (sutures) to close. However, many IOLs are flexible, allowing a smaller incision that requires few or no stitches. The surgeon folds this type of lens and inserts it into the empty capsule where the natural lens used to be. Once inside the eye, the folded IOL unfolds, filling the empty capsule.

 

Cataract surgery, usually an outpatient procedure, takes an hour or less to perform. First, your doctor will place eyedrops in your eye to dilate your pupil. You’ll receive local anesthetics to numb the area, and you may be given a sedative to help you relax. If you’re given a sedative, you may remain awake, but groggy, during surgery. During cataract surgery, the clouded lens is removed, and a clear artificial lens is usually implanted. In some cases, however, a cataract may be removed without implanting an artificial lens. A laser or an ultrasound probe, will be used to break up the lens for removal. During a procedure called phacoemulsification, your surgeon makes a tiny incision in the front of your eye (cornea) and inserts a needle-thin probe into the lens substance where the cataract has formed, to suction out the fragments of the lens. Using an advanced laser technique to remove the cloudy lens. In laser-assisted cataract surgery, the surgeon uses a laser to make all incisions and soften the cataract for removal. Once the cataract pieces have been removed the artificial lens is implanted into the empty lens capsule. After surgery, expect your vision to begin improving within a few days. Your vision may be blurry at first as your eye heals and adjusts. Colors may seem brighter after your surgery because you are looking through a new, clear lens. A cataract is usually yellow- or brown-tinted before surgery, muting the look of colors. You’ll usually see your eye doctor a day or two after your surgery, the following week, and then again after about a month to monitor healing. It’s normal to feel itching and mild discomfort for a couple of days after surgery. Avoid rubbing or pushing on your eye. The surgeon will cover the healing eye with an eye patch or protective shield the day of surgery; and may also recommend wearing the eye patch for a few days after surgery along with the protective shield when you sleep during the recovery period. Doctor usually prescribe eyedrops or other medication to prevent infection, reduce inflammation and control eye pressure. Sometimes, steroid medications can be injected into the eye at the time of surgery to keep inflammation at bay. After a couple of days, most of the discomfort should disappear. Often, complete healing occurs within eight weeks. Most people need glasses, at least some of the time, after cataract surgery. The doctor will inform whether the eye has healed enough to get a final prescription for eyeglasses. This is usually between one and three months after surgery.

 

Ophthalmology surgeons prefer to use the laser because it is simpler and quicker. While the laser avoids certain sources of human error and automates multiple steps of cataract surgery, users must still pay careful attention to what the laser will be doing. The precision benefits of the laser make surgeons very trusting of its performance. However, surgeons must be mindful to not flash quickly through all of the screens, assuming that the OCT pick-up of the lens capsule position is always correct. Results of a randomized controlled, real-world study in which the ophthalmologists-in-training were doing the surgery showed that FLACS significantly reduced the average total time spent in the OR compared with conventional phacoemulsifcation. The FS laser pretreatment reduces the duration of the operation. Most eye surgeons see the potential for laser surgery, offering a huge change in a world where cataract surgery will become even more automated and performed by a dedicated subspecialty group of surgeons. After the procedure, you usually stay in the doctor’s office for about an hour to make sure your eye pressure doesn’t rise. Other complications are rare but can include increased eye pressure and retinal detachment. The Johns Hopkins Medicine website reports that cataract surgery is among the 9) ___ (and pain free) surgeries performed today. For most people, cataract surgery is an outpatient procedure. After 10) ___, you’ll probably spend one or two hours in the post-op room with a protective eye covering. You should arrange for someone to drive you home and pick up any prescriptions, as you may not be able to drive right away

 

According to an AARP telephone survey of 250 people who had cataract surgery, 2 out of 3 said they were less dependent on glasses for distance vision after surgery. Additionally, two-thirds said they could read better (with or without glasses) after surgery, and 82% said cataract surgery made it easier to drive.

 

Sources: Mayo ClinicOphthalmology Times ; Wikipedia;

 

Click to see a short video describing cataract surgery.

 

ANSWERS: 1) retina; 2) vision; 3) aging; 4) glasses; 5) Blindness; 6) nerve; 7) bleeding; 8) artificial; 9) safest; 10) surgery

 

Filed Under News | Leave a Comment 

Cataract Surgery

A cataract surgery. Dictionnaire Universel de Medecine (1746-1748).

Graphic credit: Robert James (1703-1776); Wikipedia Commons; This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author’s life plus 100 years or less. This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights.

 

 

Cataract surgery is one of the most frequently performed operations in the world. Recent advances in techniques and instrumentation have resulted in earlier intervention, improved surgical outcomes, and reduced dependence on spectacles.

 

The first record of cataract being surgically treated is by Susruta, who carried out the procedure in 600 BCE. Cataracts were treated using a technique known as couching, in which the opaque lens is pushed into the vitreous cavity to remove it from the visual axis. Couching is still performed in some parts of Africa and the Middle East. In 1753, Samuel Sharp performed the first intracapsular cataract extraction (ICCE) through a limbal incision. He used pressure from his thumb to extract the lens. In 1961, Polish surgeon Tadeusz Krwawicz developed a cryoprobe which could be used to grasp and extract cataracts during ICCE surgery. However, an aphakic spectacle correction was still required. When the first edition of the Community Eye Health Journal was published, ICCE was still the most widely practiced method of cataract extraction in low- and middle-income countries. However, in high-income countries, ICCE had been superseded by extracapsular surgery with an IOL implant.

 

Modern extracapsular cataract extraction (ECCE) gained acceptance in high-income countries after the introduction of operating microscopes during the 1970s and 1980s made it possible to perform microsurgery. The microscopes offered better intraocular visibility and the ability to safely place multiple corneal sutures. ECCE has the advantage of leaving the posterior capsule intact; this reduces the risk of potentially blinding complications and makes it possible to implant a lens in the posterior chamber. Phacoemulsification was introduced in 1967 by Dr Charles Kelman. Since then, there have been significant improvements in the fluidics, energy delivery, efficiency and safety of this procedure. Advantages include small incision size, faster recovery and a reduced risk of complications.

 

Manual small-incision cataract surgery (MSICS) is a small-incision form of ECCE with a self-sealing wound which is mainly used in low-resource settings. MSICS has several advantages over phacoemulsification, including shorter operative time, less need for technology and a lower cost. It is also very effective in dealing with advanced and hard cataracts. As with modern ECCE techniques, MSICS also allows for a lens to be implanted. A recent introduction is femtosecond laser-assisted cataract surgery, during which a laser is used to dissect tissue at a microscopic level. Initial results from the recent FEMCAT trial suggest little or no improvement in safety and accuracy compared to standard phacoemulsification, and the procedure brings with it new clinical and financial challenges. Today, although phacoemulsification is considered the gold standard for cataract removal in high-income countries, MSICS is hugely popular and practiced widely in many countries of the world because of its universal applicability, efficiency and low cost.

 

Over the three decades since the first issue of the Community Eye Health Journal was published, the availability of microsurgery and high-quality intraocular lenses (IOLs), at an acceptable cost, have made a positive global impact on visual results after cataract surgery. IOLs can be placed in the anterior chamber or posterior chamber, or be supported by the iris. The preferred location is the posterior chamber, where the posterior chamber IOL (or PCIOL) is supported by the residual lens capsule. Sir Harold Ridley is credited with the first intraocular lens implantation in 1949, using a material known as PMMA. Since then, numerous design and material modifications have been developed to make IOLs safer and more effective, and they have been in routine use in high-income countries since the 1980s. However, when the first edition of the CEHJ was published in 1988, an IOL cost approximately $200 and was far too expensive for widespread use in low- and middle-income countries. Thankfully, owing to the foresight and innovation of organizations such as the Fred Hollows Foundation and Aravind Eye Hospitals, IOLs are now produced at low cost in low- and middle-income countries and have become available to even the most disadvantaged patients.

 

With the introduction of the first multifocal and toric IOLs, the focus of IOL development has shifted toward improving refractive outcomes and reducing spectacle dependence. Toric lenses correct postoperative astigmatism, and multifocal lenses reduce dependency on spectacles for near vision. However, multifocal lenses may cause glare and reduced contrast sensitivity after surgery and should only be used in carefully selected patients. The accommodating lenses that are in current use are limited by their low and varied amplitude of accommodation. The light-adjustable lens is made of a photosensitive silicone material. Within two weeks of surgery, the residual refractive error (sphero-cylindrical errors as well as presbyopia) can be corrected by shining an ultraviolet light on the IOL through a dilated pupil to change the shape of the lens. Development of an intraocular lens (IOL) as a drug delivery device has been pursued for many years. Common postoperative conditions such as posterior capsular opacification (PCO), intraocular inflammation or endophthalmitis are potential therapeutic targets for a drug-eluting IOL.

Sources: British Council For Prevention of Blindness; Community Eye Health Journal is published by the International Centre for Eye Health, a research and education group based at the London School of Hygiene and Tropical Medicine (LSHTM), one of the leading Public Health training institutions in the world. Unless otherwise stated, all content is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

 

Filed Under History of Medicine, News | Leave a Comment 

← Previous PageNext Page →