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Clawed salamanders of the genus Onychodactylus are among the most interesting amphibians, not just by having claws. Unlike most other amphibians, they do not have lungs but breathe through their skin, a feature especially shared with species of the amphibian family Plethodontidae. Clawed salamanders are representatives of another family, Hynobiidae, which is considered to have the most primitive characteristics among all the recent, tailed amphibians. However, both evolutionary derived features and characteristics even more primitive than in other hynobiids are combined in their morphology. The geographical distribution of the clawed salamanders is limited to a few mountain systems in the continental Far East and Japan. This is related to their pronounced environmental requirements; clear and cool mountain upstreams, high air humidity, and mild winters are all necessary. Although the clawed salamanders have been known to scientists for more than 200 years, many aspects of their life remain an enigma. Additionally, because of peculiarities of their distribution, most of the data have been published in Japanese, Russian, Chinese and Korean, thus have remained almost unavailable to Western readers. This book aims to present an overview of all available information. It is intended not only for professional herpetologists, but everybody interested in the nature of the Far East, as well as professional and amateur amphibian keepers.
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Drought is tough on insect eaters
The color-changing lizards commonly known as chameleons are always fun to watch. Especially fascinating is how these agile, long-tailed lizards switch from dull brown when perched on a wood post to bright green when they move to a leaf.
These lizards are anoles (pronounced ah-NO-lees). Recently my wife Minnie and I saw a large green anole resting on one of the steel pipes of our driveway gate. Several times he displayed his bright red dewlap under his throat while we watched.
Hopefully that anole will find a mate, but that may be difficult. In spite of recent rain, the anole population on our place has been set back by drought.
No anoles were spotted on our place during 2008 and 2009. They were last covered in this column in November 2010, when three were seen that fall. Only one was observed during the severe drought year of 2011. They weren't seen during 2012.
During drought years, city residences and parks with well-watered lawns and gardens are perfect territory for anoles unless insecticides are in use. So if you enjoy watching anoles, you might want to consider them a substitute for insecticides. That's because anoles dine on insects and the spiders that also consume them.
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Drought has greatly reduced the insect population on our place, which probably explains the very few anoles and fence lizards observed here in recent years.
More evidence for the lack of insects is the reduced spider population. While ground spiders are roaming our grassy field at night, so far only a few orb weaving spider webs have been noticed along a mile of trail.
Prior to the 2011 drought, our woods were sprinkled with hundreds of orb webs constructed by half a dozen species of spiders. Some of those webs were several feet or more across.
Paper wasps also have been in short supply, possibly because of the sharply reduced population of caterpillars they capture and eat.
Nighthawks, dragonflies, bats and swallows are also insect eaters. Some of these fliers have returned, but I've not seen any bats this spring.
Near-normal rain at our place this spring has been accompanied by the return of many insects, including fireflies, carpenter bees, honeybees, dragonflies, ladybugs, butterflies, moths, crickets and many others.
In early May, before major rain arrived, only a few honeybees visited our place. Recently hundreds were observed sipping nectar and collecting pollen from fire wheels and other wild flowers.
These developments dramatically illustrate the aftereffects of drought on the population of insects and insect eaters including spiders, birds, bats and the bright green anole we recently observed.
Forrest Mims, an amateur scientist whose research has appeared in leading scientific journals, was named one of the “50 Best Brains in Science” by Discover Magazine. His science is featured at www.forrestmims.org. Email him at email@example.com. | <urn:uuid:550b2f0c-3cdc-4f2a-955a-9b57c130937e> | 2.546875 | 973 | Nonfiction Writing | Science & Tech. | 49.911748 | 95,596,012 |
Phonon-Dispersion Measurements in Glasses
The phonon-dispersion relation is one of the most fundamental properties of the solids. In particular, its knowledge is required for the explanation of the low-temperature thermal properties. Unfortunately, this relation can not be measured in glasses with neutron-scattering techniques because of the absence of a lattice periodicity. In addition, if the glass is only available as thin film, not even the sound velocity, the slope of the dispersion curve at the low-frequency end, can be determined by the standard ultrasonic techniques.
KeywordsSound Velocity Tunnel Junction Phonon Scattering Phonon Dispersion Lattice Periodicity
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A study by researchers at New York University and the University of London offers additional evidence that mammals and fruit flies share a common genetic makeup that determines the function of their internal biological clocks. The study appears in the latest issue of Current Biology. The research team consisted of post-doctoral researcher Ben Collins, Esteban Mazzoni, a graduate student, and Assistant Professor Justin Blau of NYUs Department of Biology and Professor Ralf Stanewsky of the University of London.
Drosophila fruit flies are commonly used for research on biological, or circadian, clocks because of the relative ease of finding mutants with non-24-hour rhythms and then identifying the genes underlying the altered behavior. These studies in fruit flies have allowed the identification of similar "clock genes" in mammals, which function in a similar manner in mammals as they do in a flys clock. However, prior to this study, biologists had concluded that the role of one protein--Cryptochrome (Cry)--was quite different between flies and mammals. In fruit flies, Cry is a circadian photoreceptor, which helps light reset the biological clock with changing seasons, or in jet lag-style experiments (in which light is manipulated to mimic the experience of traveling over multiple time zones) in the lab. In mammals, however, Cry assists in the 24-hour rhythmic expression of clock genes and has nothing to do with re-setting the clock.
The researchers sought to determine additional roles for Cry in fruit flies by testing the rhythmic expression of clock genes in flies with either a mutant version of Cry, or with Cry produced at artificially high levels. In both cases, they found that the clock had stopped – with high levels of clock gene expression when Cry was mutated, and low levels when Cry was over-produced. These results indicated that Cry normally inhibits clock gene expression in many clock cells – just as it does in the mammalian clock.
James Devitt | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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NYSCF researchers develop novel bioengineering technique for personalized bone grafts
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Introducing Chan's megastick: The record-breaking insect as long as your arm
In the stick insect world, it's the queen of the jungle. Stretching to an extraordinary 22 inches, this newly discovered bug is the longest stick insect in the world.
Named the Chan's megastick, it was discovered in the Borneo rainforests by a stick insect enthusiast and has been handed to the Natural History Museum in London.
The creature is nearly half an inch longer than the previous record holder.
Meet the mother of all stick insects: Jane Lucas of the Natural History Museum displays the longest stick insect in the world
Dr George Beccaloni, curator of stick insects, cockroaches and grasshoppers at the museum, said: 'We've known about both the previous record holders for over 100 years, so it's extraordinary an even bigger species has only just been discovered.'
The dead creature, a female, was found by a collector, who kept it for ten years. The owner had no idea of its significance until an entomologist, Datuk Chan Chew Lun, saw it in the collection and realised it was a new species.
Almost nothing is known about its biology and lifestyle, although it probably lives in the highest canopies of the rainforest, making it hard to spot.
Its body without legs is 14 inches long. In addition to its size, its eggs may also be unique in the insect world, Dr Beccaloni said.
The female sent to the museum was full of eggs, each had wing-like extensions on either side like a miniature golden snitch - the Quidditch ball from the Harry Potter books.
'Other stick insects lay their 0.5 cm eggs individually and flick them in to the air where they fall to the ground,' he said.
'It looks like these are flicked into the air where they can be picked up by the wind and carried away from the tree.
'It increases the dispersal of the eggs and means that the young don't climb up the same tree as the parents and start competing for the same food.'
Only three specimens of the new insect have been found so far - all from the Malaysian state of Sabah on the island of Borneo.
The record-breaking stick insect is more than half a metre long with legs outstretched,
The previous largest insect in the world was called Phobaeticus serratipes, found in Malaysia and Indonesia.
British scientist Dr Philip Bragg described and named this stick insect for the first time this week in the journal Zootaxa.
Stick insects may be the longest insects in the world, but others are bulkier.
The South American Acteon beetle, for instance, is up to 3.5 inches long, 2 inches wide and 1.5 inches thick.
One of the heaviest insects ever found was a pregnant giant weta - a rare, endangered beetle from New Zealand which weighed in a just over two ounces.
Goliath beetles - members of the scarab family - are also candidates for the biggest insect. Some can weigh 3.5 ounces.
Some sticky facts:
- Although they do not occur naturally in Britain, three species from New Zealand have become settled in the south-west of England and the Isles of Scilly
- Stick insects sleep in the day, making them notoriously dull pets. However, at night they spring into action and eat leaves
- Experts believe the newly discovered Chan's megastick is already two and a half inches long when it hatches
- Stick insects are masters of camouflage. Their appearance allows them to hide from birds, their main predator.
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The orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a chronic wheat pest worldwide. Adult S. mosellana engage in short-distance flight, but also exploit weather patterns for long-distance dispersal. However, little is known about the flight performance of S. mosellana, and the effects of the biotic and abiotic factors that influence its flight activity. In this study, we explored the active flight potential of S. mosellana under various environmental factors using a 26-channel computer-monitored flight mill system. The most suitable temperature for flight and flight distance was 16-24 degrees C; flight duration peaked at 16 degrees C while speed peaked at 28 degrees C. Flight performance gradually declined between 10 and 400 lux light intensity. More than 50% individuals of 1-d-old females flew > 500 m, while only 24% of males flew > 500 m. One-day-old S. mosellana had stronger flight ability than that of 2-d-old individuals. This research showed that S. mosellana possessed strong enough flight ability that they can fly to a high altitude and then disperse via moving air currents. These results can aid in forecasting S. mosellana outbreak.
Mendeley saves you time finding and organizing research
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Author: Richard E. Berg
Release Date: 1995
This text provides an introduction to acoustics, appropriate for introductory courses on the physics of sound and musical acoustics at undergraduate level. This edition places emphasis on modern instruments.
Author: Richard E. Berg
Release Date: 2005
This book incorporates the developments in digital audio technology, including consumer products, into a firm foundation of the physics of sound. No knowledge of physics, mathematics, or music is required. Includes updated information on musical synthesizers. Provides recent information on the ear, including new advances in cochlear implant technology. Updates material for modern technology, particularly MP3. Features abundant examples, including discussion of demonstration experiments. Includes historical discussion of musical temperaments and instruments. Offers videotapes of musical demonstrations on topics discussed in the book, available from author. A useful reference for musicians or anyone interested in learning more about the physics of music.
Author: Thomas D. Rossing
Publisher: Pearson Higher Ed
Release Date: 2013-10-03
The Science of Sound is widely recognized as the leading textbook in the field. It provides an excellent introduction to acoustics for students without college physics or a strong background in mathematics. In the Third Edition, Richard Moore and Paul Wheeler join Tom Rossing in updating The Science of Sound to include a wide range of important technological developments in the field of acoustics. New exercises and review questions have been added to the end of each chapter to help students study the material.
Author: William M. Hartmann
Publisher: Springer Science & Business Media
Release Date: 2013-07-26
Principles of Musical Acoustics focuses on the basic principles in the science and technology of music. Musical examples and specific musical instruments demonstrate the principles. The book begins with a study of vibrations and waves, in that order. These topics constitute the basic physical properties of sound, one of two pillars supporting the science of musical acoustics. The second pillar is the human element, the physiological and psychological aspects of acoustical science. The perceptual topics include loudness, pitch, tone color, and localization of sound. With these two pillars in place, it is possible to go in a variety of directions. The book treats in turn, the topics of room acoustics, audio both analog and digital, broadcasting, and speech. It ends with chapters on the traditional musical instruments, organized by family. The mathematical level of this book assumes that the reader is familiar with elementary algebra. Trigonometric functions, logarithms and powers also appear in the book, but computational techniques are included as these concepts are introduced, and there is further technical help in appendices.
Most books concerned with physics and music take an approach that puts physical theory before application. Consequently, these works tend to dampen aesthetic fascination with preludes burdened by an overabundance of algebraic formulae. In Measured Tones: The Interplay of Physics and Music Third Edition, Ian Johnston a professor of astrophysics and a connoisseur of music, offers an informal historical approach that shows the evolution of both theory and application at the intersection of physics and music. Exceptionally accessible, insightful, and now updated to consider modern technology and recent advances, the new edition of this critically acclaimed and bestselling classic — Features a greater examination of psycho-acoustics and its role in the design of MP3s Includes expanded information on the gamelan and other Asian percussion instruments Introduces detailed discussions of binary notation, digitization, and electronic manipulation of music We believe that order exists, and we look for it. In that respect the aims of science and of music are identical—the desire to find harmony. And surely, without that very human desire, science would be a cold and sterile undertaking. With myriad illustrations and historical anecdotes, this volume will delight those student required to approach this topic from either a physics and music concentration, as well as anyone who is fascinated with concepts of harmony expressed in nature, as well as in the instruments and composition of human expression’s purest form. A complementary website provides sound files, further reading, and instructional support.
Author: Juan Roederer
Publisher: Springer Science & Business Media
Release Date: 2008-12-15
This book uses acoustics, psychophysics, and neurobiology to explore the physical systems and biological processes that intervene when we hear music. It incorporates the latest findings in brain science and tone generation in musical instruments.
Sound Systems: Design and Optimization provides an accessible and unique perspective on the behavior of sound systems in the practical world. The third edition reflects current trends in the audio field thereby providing readers with the newest methodologies and techniques. In this greatly expanded new edition, you’ll find clearer explanations, a more streamlined organization, increased coverage of current technologies and comprehensive case studies of the author’s award-winning work in the field. As the only book devoted exclusively to modern tools and techniques in this emerging field, Sound Systems: Design and Optimization provides the specialized guidance needed to perfect your design skills. This book helps you: Improve your design and optimization decisions by understanding how audiences perceive reinforced sound Use modern analyzers and prediction programs to select speaker placement, equalization, delay and level settings based on how loudspeakers interact in the space Define speaker array configurations and design strategies that maximize the potential for spatial uniformity Gain a comprehensive understanding of the tools and techniques required to generate a design that will create a successful transmission/reception model
Author: Andrey Varlamov
Publisher: World Scientific Publishing Company
Release Date: 2012-03-22
The book in your hands develops the best traditions of Russian scientific popular literature. Written in a clear and captivating manner by working theoretical physicists, who are, at the same time, dedicated popularizers of scientific knowledge, it brings to the reader the latest achievements in quantum solid-state physics, but along the way also shows how the laws of physics reveal themselves even in seemingly trivial episodes concerning the natural phenomena around us. Most importantly, it shows that we live in a world where scientists are capable of “proving harmony with algebra”. — A A Abrikosov, 2003 Nobel Prize Winner in Physics The third edition is considerably extended with three new chapters where the author discusses exciting examples of applications of recent achievements of physics in medicine, nanotechnologies, and physics in cuisine.
Sound for Film and Television, Third Edition provides a thorough introduction to the fascinating field of recording, editing, mixing, and exhibiting film and television sound. It strikes a fine balance between aesthetic and technical content, combining theory and practice to approach sound as both an art and a science. This new edition has been completely updated to reflect the latest advances in HD technology, new hardware and software systems, new distribution methods, wireless sound capture, and more. Also, analog-related content has been reduced and transferred to the chapters covering historical techniques. Sections on troubleshooting and FAQs have been added to help you avoid common pitfalls in sound production. Written by one of Hollywood's leading sound experts, Sound for Film and Television provides a solid grounding in all aspects of the sound process. Basic principles are presented with illustrations demonstrating how they affect the day-to-day activities on a film or television set, in the editing room, and in the mix room. The accompanying audio DVD contains more than 50 tracks that demonstrate practical, real-world examples of key concepts presented in the book. A companion Web site provides further resources and information: http://booksite.focalpress.com/companion/Holman/SoundforFilmandTelevision/ Please use the access code located in the beginning of the book to register for access to the Web site.
Author: Neville H. Fletcher
Publisher: Springer Science & Business Media
Release Date: 2013-11-09
While the history of musical instruments is nearly as old as civilisation itself, the science of acoustics is quite recent. By understanding the physical basis of how instruments are used to make music, one hopes ultimately to be able to give physical criteria to distinguish a fine instrument from a mediocre one. At that point science may be able to come to the aid of art in improving the design and performance of musical instruments. As yet, many of the subtleties in musical sounds of which instrument makers and musicians are aware remain beyond the reach of modern acoustic measurements. This book describes the results of such acoustical investigations - fascinating intellectual and practical exercises. Addressed to readers with a reasonable grasp of physics who are not put off by a little mathematics, this book discusses most of the traditional instruments currently in use in Western music. A guide for all who have an interest in music and how it is produced, as well as serving as a comprehensive reference for those undertaking research in the field.
Physics in Biology and Medicine, Fourth Edition, covers topics in physics as they apply to the life sciences, specifically medicine, physiology, nursing and other applied health fields. This is a concise introductory paperback that provides practical techniques for applying knowledge of physics to the study of living systems and presents material in a straightforward manner requiring very little background in physics or biology. Applicable courses are Biophysics and Applied Physics. This new edition discusses biological systems that can be analyzed quantitatively, and how advances in the life sciences have been aided by the knowledge of physical or engineering analysis techniques. The volume is organized into 18 chapters encompassing thermodynamics, electricity, optics, sound, solid mechanics, fluid mechanics, and atomic and nuclear physics. Each chapter provides a brief review of the background physics before focusing on the applications of physics to biology and medicine. Topics range from the role of diffusion in the functioning of cells to the effect of surface tension on the growth of plants in soil and the conduction of impulses along the nervous system. Each section contains problems that explore and expand some of the concepts. The text includes many figures, examples and illustrative problems and appendices which provide convenient access to the most important concepts of mechanics, electricity, and optics in the body. Physics in Biology and Medicine will be a valuable resource for students and professors of physics, biology, and medicine, as well as for applied health workers. Provides practical techniques for applying knowledge of physics to the study of living systems Presents material in a straight forward manner requiring very little background in physics or biology Includes many figures, examples and illustrative problems and appendices which provide convenient access to the most important concepts of mechanics, electricity, and optics in the body
Our economy and future way of life depend on how well American manufacturing managers adapt to the dynamic, globally competitive landscape and evolve their firms to keep pace. A major challenge is how to structure the firms environment so that it attains the speed and low cost of high-volume flow lines while retaining the flexibility and customization potential of a low-volume job shop. The books three parts are organized according to three categories of skills required by managers and engineers: basics, intuition, and synthesis. Part I reviews traditional operations management techniques and identifies the necessary components of the science of manufacturing. Part II presents the core concepts of the book, beginning with the structure of the science of manufacturing and a discussion of the systems approach to problem solving. Other topics include behavioral tendencies of manufacturing plants, push and pull production systems, the human element in operations management, and the relationship between quality and operations. Chapter conclusions include main points and observations framed as manufacturing laws. In Part III, the lessons of Part I and the laws of Part II are applied to address specific manufacturing management issues in detail. The authors compare and contrast common problems, including shop floor control, long-range aggregate planning, workforce planning and capacity management. A main focus in Part III is to help readers visualize how general concepts in Part II can be applied to specific problems. Written for both engineering and management students, the authors demonstrate the effectiveness of a rule-based and data driven approach to operations planning and control. They advance an organized framework from which to evaluate management practices and develop useful intuition about manufacturing systems.
Ideal for use with any introductory physics text, Loyd’s PHYSICS LABORATORY MANUAL is suitable for either calculus- or algebra/trigonometry-based physics courses. Designed to help students demonstrate a physical principle and learn techniques of careful measurement, Loyd’s PHYSICS LABORATORY MANUAL also emphasizes conceptual understanding and includes a thorough discussion of physical theory to help students see the connection between the lab and the lecture. Available with InfoTrac Student Collections http://gocengage.com/infotrac. Important Notice: Media content referenced within the product description or the product text may not be available in the ebook version.
Extensively revised and updated to keep abreast of recent advances, Polymers: Chemistry and Physics of Modern Materials, Third Edition continues to provide a broad-based, high-information text at an introductory, reader-friendly level that illustrates the multidisciplinary nature of polymer science. Adding or amending roughly 50% of the material, this new edition strengthens its aim to contribute a comprehensive treatment by offering a wide and balanced selection of topics across all aspects of the chemistry and physics of polymer science, from synthesis and physical properties to applications. Although the basics of polymer science remain unchanged, significant discoveries in the area of control over molecular weight, macromolecular structure and architecture, and the consequent ability to prepare materials with specific properties receive extensive mention in the third edition. Expanded chapters include controlled radical polymerizations, metallocene chemistry, and the preparation of block and graft copolymers, as well as multiarmed and dendritic structures. Reflecting the growth of polymer applications in industry, the book presents detailed examples to illustrate polymer use in electronic, biological, and medical settings. The authors introduce new understandings of rheological behavior and replace old and outmoded methods of polymer characterization with new and up-to-date techniques. Also new to this edition are a series of problems at the end of each chapter that will test whether the reader has understood the various points and in some cases expand on that knowledge. An accompanying solutions manual is also available for qualifying course adoptions. Offering the highest quality, comprehensive coverage of polymer science in an affordable, accessible format, Polymers: Chemistry and Physics of Modern Materials, Third Edition continues to provide undergraduate and graduate students and professors with the most complete and current coverage of modern polymer science. | <urn:uuid:a4bd7650-a98d-429c-8015-276f601d2059> | 3.21875 | 2,943 | Content Listing | Science & Tech. | 16.205434 | 95,596,066 |
The Dubious Promise of Bioenergy Plus Carbon Capture
Climate change agreements rest on negative emissions technologies that may be unachievable.
Eliminating carbon dioxide that’s already been emitted is essential to achieve the goals of the Paris climate agreement.
While many scientists and climate change activists hailed December’s Paris agreement as a historic step forward for international efforts to limit global warming, the landmark accord rests on a highly dubious assumption: to achieve the goal of limiting the rise in global average temperature to less than 2 °C (much less the more ambitious goal of 1.5 °C), we don’t just need to reduce emissions of carbon dioxide to essentially zero by the end of this century. We also must remove from the atmosphere huge amounts of carbon dioxide that have already been emitted (see “Paris Climate Agreement Rests on Shaky Technological Foundations”).
Doing so will involve “negative emissions technologies”—systems that capture carbon dioxide and store it, usually deep underground. Such technologies are theoretical at best, but they are considered critical for achieving the Paris goals. Of the 116 scenarios reviewed by the Intergovernmental Panel on Climate Change to achieve stabilization of carbon in the atmosphere at between 430 and 480 parts per million (the level considered necessary for a maximum 2 °C rise in temperature), 101 involve some form of negative emissions.
There are basically two ways to eliminate carbon from the atmosphere. One is to capture it from the air. Technologies to do so are still in their infancy and, even if they do prove practical, are likely decades away from deployment—far too late to achieve the goals of the Paris agreement (see “Materials Could Capture CO2 and Make It Useful”). The other is to rely on plants to capture the carbon dioxide, then burn the plants to generate power (or refine them into liquid fuels such as ethanol), and capture the resulting carbon emissions. Known as “bioenergy plus carbon capture and storage,” or BECCS, this cumbersome process is receiving renewed attention in the wake of Paris. But there is no guarantee that it will ever work.
Large amounts of biomass would be produced from fast-growing trees, switchgrass, agriculture waste, or other sources. The biomass would then be turned into pellets for burning in power plants—either on their own or as additives. The resulting emissions would be separated using carbon-capture technologies that have been proven at small scale but have never been applied economically at anything like commercial scale. Finally, the carbon dioxide would be stored in deep-underground aquifers, presumably permanently.
While each of these steps is technically feasible, neither has proven to be successful at a large scale. Although there are dozens of projects that use biomass, either alone or in combination with other fuels such as coal, for producing electricity, there are serious doubts about the economic viability of the sector, the availability of biomass supplies to support growth, and the life-cycle contribution of such facilities to greenhouse gas emissions. Ambitious projections for carbon capture and storage programs, meanwhile, have proven unrealistic, and there is little indication that such systems will become economically viable in the foreseeable future.
What’s more, although the full BECCS process is often touted as carbon-negative, there are several faulty assumptions in that characterization.
The first is that sufficient amounts of biomass could be produced to displace a significant percentage of fossil-fuel produced electricity, and that producing those amounts would be carbon-neutral. Advocates assert that because plants capture carbon from the atmosphere, burning the plants and releasing the carbon back into the atmosphere does not result in a net gain. That is nominally true, but it doesn’t account for the energy required for growing, harvesting, processing, and transporting the biomass, and it diverts land from other purposes, including food crops, that will become more urgent as the human population surges toward nine billion.
The most prominent BECCS project currently underway is Archer Daniels Midland’s project at Decatur, Illinois. The project has been years in development. “Permitting has been a long and complex process,” says Scott McDonald, the project manager. And it still awaits final approval from the U.S. Environmental Protection Agency. Once it’s complete, the captured carbon will not be stored underground but used for enhanced oil recovery in nearby wells. Studies have estimated that about a billion barrels of residual oil could be recovered in the Illinois basin using carbon dioxide for enhanced oil recovery. In other words, a technology advertised as carbon-negative would result in the production of a billion new barrels of carbon-producing fossil fuels—oil that would not otherwise be produced. That is hardly a climate-friendly solution.
Already, some proposed BECCS projects have foundered on these obstacles. In September, Drax, one of the largest power companies in the U.K., pulled out of the White Rose Carbon Capture Project, which would capture 90 percent of the carbon emissions from a 428-megawatt plant that burns coal and biomass. Drax has converted three of the six coal-fired turbines at the site to burn biomass. The fate of the carbon-capture project in the wake of Drax’s departure is uncertain. The experience of “clean coal” projects using carbon capture and storage, without biomass, is similarly discouraging: FutureGen, a highly touted CCS project in Illinois, was finally canceled in February 2015 after multiple setbacks.
In short, BECCS represents the marriage of two technologies, neither of which has proven to be viable on its own. The technology’s “credibility as a climate change mitigation option is unproven,” concluded a September 2014 study in Nature Climate Change led by Sabine Fuss, a scientist at the Mercator Research Institute on Global Commons and Climate Change in Berlin, “and its widespread deployment in climate stabilization scenarios might become a dangerous distraction.”
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:0b057daf-2441-47d9-b975-72f7ec0a5265> | 3.609375 | 1,250 | Truncated | Science & Tech. | 29.013373 | 95,596,086 |
New technology is helping more people see Frank Lloyd Wright’s winter home.
99 Percent Of Arizona Forest Fires So Far This Year Were Man-Made
Since Jan. 1, 2018, there have been 152 forest fires in Arizona; 150 of them were man-made.
“One spark is really all it takes to cause a wildfire,” Arizona Department of Forestry and Fire Management spokeswoman Tiffany Davila said.
“We want everybody to be safe and use their heads,” she said. “When they’re out on the road, don’t drags tow chains. If they’re camping, put out your campfires completely before walking away and make sure they’re cool to the touch.”
Arizona had a dry winter, and low precipitation combined with rising temperatures can lead to disaster for forests in northern and southern Arizona.
Last year 100,000 more acres burned than in 2016, Davila said. It’s forecasted to be a hot summer, and Davila said prevention was the key to ensure the trend of hotter and longer — burning wildfire doesn’t continue into 2018. | <urn:uuid:61d8a24b-1e30-482f-906e-99e09ec9f220> | 2.9375 | 238 | News Article | Science & Tech. | 55.822136 | 95,596,094 |
Clathrates are now known to store enormous quantities of methane and other gases in the permafrost as well as in vast sediment layers hundreds of metres deep at the bottom of the ocean floor.
Their potential decomposition could therefore have significant consequences for our planet, making an improved understanding of their properties a key priority.
In a paper published in Nature this week, scientists from the University of Göttingen and the Institut Laue Langevin (ILL) report on the first empty clathrate of this type, consisting of a framework of water molecules with all guest molecules removed.
Long thought to be purely hypothetical, this empty clathrate plays an important role in our understanding of the physical chemistry of gas hydrates. Such research could help ease the flow of gas and oil through pipelines in low temperature environments, and open up untapped reservoirs of natural gas on the ocean floor.
In order to create the sample of Ice XVI, the researchers constructed a clathrate filled with molecules of neon gas, which they then removed by careful pumping at low temperatures. Using small atoms such as those of neon gas allowed the clathrate to be emptied without compromising its fragile structure.
In order to achieve this, the neon clathrate was pumped in a vacuum at temperatures in the region of 140° K, while neutron diffraction data was taken using the ILL's state-of-the-art D20 diffractometer. The images obtained allowed them to confirm when the clathrate had been fully emptied, and provided a complete picture of the resulting structure.
As a stable solid composed entirely of molecules of H2O, the empty clathrate also represents a new phase of ice. Ice XVI is the 17th discovered form of ice, and is the least dense of all known crystalline forms of water. It is also predicted to be a stable low-temperature configuration of water at negative pressures (the equivalent of tension - the opposite of compressive positive pressures), and is so far the only experimentally-obtained form of ice to have a clathrate configuration.
As the empty clathrate is used as a reference frame for numerous molecular simulations, scientists have up until now relied on approximate theoretical models to underpin their work. The empty clathrate framework obtained at the ILL will now allow for the accurate determination of its fundamental structural and thermodynamic properties. The ability to create and observe such empty clathrates has the potential to considerably improve our understanding of these compounds when they are filled with gas.
According to the 2007 World Energy Outlook, the total amount of methane stored within clathrates on the ocean floor far exceeds the economically exploitable reserves of "conventional" carbon in the form of coal, petrol or natural gas left on Earth. These reservoirs are difficult to exploit at present but form a domain of intense ongoing research.
Thomas Hansen, one of the study authors and instrument scientist on D20 at the ILL, says: "It is important to note that clathrates could also be formed with carbon dioxide gas which would create stable compounds on the ocean floor. This means there is a possibility we could extract methane and convert it to useful energy, and replace it with the CO2. In other words, we could pump CO2 down to the ocean floor as a replacement for the methane in the gas hydrates. The challenges involved would naturally be large and the feasibility has been called into question, but it remains an extremely intriguing possibility worth exploring.
Hansen adds: "My co-authors Andrzej Falenty and Werner F Kuhs from the University of Göttingen are both members of the SUGAR project funded by the German government, whose aim is to explore the scientific, technical and economic possibilities of such an undertaking. Similar activities are currently underway in Japan, China, India and elsewhere."
Helmut Schober, ILL Science Director, said: "Empty clathrate hydrates have for many years been the subject of intense scientific speculation, as their very existence was relatively uncertain. The present discovery definitively resolves this speculation, and provides us with a new jewel in the fascinating treasure chest of ice phases. Predicting the properties of ice XVI will be a benchmark for any model that pretends to describe the physics of water. This in itself is a tremendous step forward. It is via this understanding that we hopefully will also advance on the surrounding questions related to energy."
An area where clathrate research is of more immediate benefit is in the maintenance of pipelines where gas is transported at high pressures and low temperatures. These conditions can lead to the production of gas hydrates within the pipes, which in turn form substantial blockages, the prevention of which costs industry approximately $500 million a year worldwide. Given the high international economic impact of such pipelines, this represents a significant cost factor that further research on clathrate properties can help reduce.
James Romero | EurekAlert!
New creepy, crawly search and rescue robot developed at Ben-Gurion U
19.07.2018 | American Associates, Ben-Gurion University of the Negev
The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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The impact of a reflective, recurrent coastal resuspension plume on the lower trophic food web system in Lake Michigan was examined using a 3-D coupled physical and biological model. Numerical experiments were conducted for the March 1998 and 1999 plume events. The comparison between modeling results of these 2 years shows that the spatial distributions of the biological fields (i.e., phosphorus, phytoplankton, detritus, etc.) were closely coupled to the physical environment associated with wind-induced three-dimensional circulation and mixing. The influence of suspended sediment plumes on the lake ecosystem was reflected in heterotrophic (secondary) production rather than in the autotrophic (primary) production. Nutrients were maintained through nutrient release from suspended sediments within the plume, while it was supplied by current advection and diffusion in the interior. The cross-shore flux of nutrients was driven by episodic wind events with a period of about 5-7 days. The flux was offshore during northerly winds and onshore during southerly winds. Comparisons between energy fluxes among biological variables suggest that the microbial loop (detritus-heterotrophic bacteria and microzooplankton) played an important role in the ecosystem dynamics during plume events. Bacteria were good competitors with phytoplankton for inorganic phosphorus and were also a key supporter for growth of microzooplankton inside and outside the plume. As a result, the lower food web system could be divided into two decoupled loops: (1) detritus-bacteria-microzooplankton-large zooplankton and (2) nutrient-phytoplankton-detritus.
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Without the 'g' modifier, the m/.../ operator simply reports whether the string matches or not. Unless you change the string, it will *always* match or *always* fail. If you read perlre, it'll refer you to perlretut. In there it says:
The final two modifiers "//g" and "//c" concern multiple matches. The modifier "//g" stands for global matching and allows the matching operator to match within a string as many times as possible. In scalar context, successive invocations against a string will have `"//g" jump from match to match, keeping track of position in the string as it goes along. You can get or set the position with the "pos()" function.
The relevent bit is the italicized bit. It's telling you that with the g operator, the match remembers where it left off, and the next time you match with the g operator, it will proceed from that point.
Long story short: that's what the 'g' modifier does!
When your only tool is a hammer, all problems look like your thumb.
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NASA's James Webb Space Telescope Could Potentially Detect the First Stars and Black Holes
One of the key science goals of NASA’s James Webb Space Telescope is to learn about “first light,” the moment when the first stars and galaxies lit the universe. While the first galaxies will be within Webb’s reach, individual stars shine so faintly that Webb would not be able to detect them without help. That help could come in the form of natural magnification from gravitational lensing, according to a new theoretical paper.
A cluster of galaxies can provide the needed gravitational oomph to bring distant objects into focus via lensing. Typical gravitational lensing can boost a target’s brightness by a factor of 10 to 20. But in special circumstances, the light of a faraway star could be amplified by 10,000 times or more.
If Webb monitors several galaxy clusters a couple of times a year over its lifetime, chances are good that it will detect such a magnified star, or possibly the accretion disk of a black hole from the same era. This would give astronomers a key opportunity to learn about the actual properties of the early universe and compare them to computer models.
The first stars in the universe blazed to life about 200 to 400 million years after the big bang. Observing those very first individual stars across such vast distances of space normally would be a feat beyond any space telescope. However, new theoretical work suggests that under the right circumstances, and with a little luck, NASA's James Webb Space Telescope will be able to capture light from single stars within that first generation of stars.
“Looking for the first stars and black holes has long been a goal of astronomy. They will tell us about the actual properties of the very early universe, things we’ve only modeled on our computers until now,” said Rogier Windhorst of Arizona State University, Tempe. Windhorst is lead author of the paper that appeared in the Astrophysical Journal Supplement on February 14, 2018.
“We want to answer questions about the early universe such as, were binary stars common or were most stars single? How many heavy chemical elements were produced, cooked up by the very first stars, and how did those first stars effect star formation?” added co-author Frank Timmes of Arizona State University.
The key will be to look for a star that has been gravitationally lensed, its light bent and magnified by the gravity of an intervening galaxy cluster. But not just any gravitational lensing will do. Typical gravitational lensing can magnify light by a factor of 10 to 20 times, not enough to make a first-generation star visible to Webb.
But if the distant star and closer galaxy cluster line up just right, the star’s light can be amplified 10,000 times or more, bringing it within the realm of detectability. This could be done via so-called cluster caustic transits, where the light from a first star candidate could be enormously magnified for a few months due to the motion of the galaxy cluster across the sky.
The chances of such a precise alignment are small, but not zero. Astronomers recently announced that Hubble spotted a super-magnified star known as “Icarus.” Although it was the farthest single star ever seen, it was much closer than the stars Webb might locate. With Webb, the team hopes to find a lensed example of a star that formed from the primordial mix of hydrogen and helium that suffused the early universe, which astronomers call Population III stars.
In addition to the first stars, Windhorst and his colleagues investigated the possibility of seeing accretion disks surrounding the first black holes. Such a black hole, formed by the cataclysmic death of a massive star, could shine brightly if it pulled gas from a companion star.
The longer an object shines, the more likely it will drift into alignment with a gravitational lens. First-generation stars are expected to have been both massive and short-lived, lasting for just a few million years before exploding as supernovae. In contrast, a black hole stripping a companion star could shine for 10 times longer, feeding from a steady stream of gas. As a result, Webb might detect more black hole accretion disks than early stars.
The team calculates that an observing program that targets several galaxy clusters a couple of times a year for the lifetime of Webb could succeed in finding a lensed first star or black hole accretion disk. They have already selected some of the best target clusters, including the Hubble Frontier Fields clusters and the cluster known as “El Gordo.”
“We just have to get lucky and observe these clusters long enough,” said Windhorst. “The astronomical community would need to continue to monitor these clusters during Webb’s lifetime.”
The authors of the Astrophysical Journal Supplement paper are R. Windhorst and F. Timmes (Arizona State University), S. Wyithe (University of Melbourne), M. Alpaslan (New York University), S. Andrews (The University of Western Australia), D. Coe (Space Telescope Science Institute), J. Diego (IFCA), M. Dijkstra (University of Oslo), S. Driver (The University of Western Australia), P. Kelly (University of Minnesota, Twin Cities), and D. Kim (Arizona State University).
The James Webb Space Telescope is the world’s premier infrared space observatory of the next decade. Webb will solve mysteries of our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, the European Space Agency (ESA) and the Canadian Space Agency (CSA). | <urn:uuid:cec369cb-75a0-4a80-b2aa-5f8b82b1f381> | 4.25 | 1,200 | News (Org.) | Science & Tech. | 46.276616 | 95,596,112 |
Evolution has selected a system of two intertwined cell cycles: the cell division cycle (CDC) and the daily (circadian) biological clock. The circadian clock keeps track of solar time and programs biological processes to occur at environmentally appropriate times. One of these processes is the CDC, which is often gated by the circadian clock. The intermeshing of these two cell cycles is probably responsible for the observation that disruption of the circadian system enhances susceptibility to some kinds of cancer. The core mechanism underlying the circadian clockwork has been thought to be a transcription & translation feedback loop (TTFL), but recent evidence from studies with cyanobacteria, synthetic oscillators and immortalized cell lines suggests that the core circadian pacemaking mechanism that gates cell division in mammalian cells could be a post-translational oscillator (PTO).
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Researchers at the University of Texas Medical Branch at Galveston (UTMB) have discovered a quick new way that mosquitoes can pass West Nile virus to each other. The new study challenges fundamental assumptions about the virus transmission cycle and may help explain why it spread so rapidly across North America despite experts predictions that it would progress more slowly or even die out. In the conventional understanding of West Nile transmission, mosquitoes acquire the virus when they bite birds with high levels of virus (or "high viremia.") in their blood. Those levels are reached several days after the birds are initially infected by other mosquitoes. But experiments at UTMB show that when infected and uninfected mosquitoes feed simultaneously on previously uninfected laboratory mice, the virus can pass from mosquito to mosquito within an hour.
"We were amazed to see that it could happen," said UTMB associate professor Stephen Higgs, lead author of a paper on the discovery that will be published online in the Proceedings of the National Academy of Sciences the week of June 6. "It is basically a brand-new component of the virus life cycle."
In the paper, Higgs and his co-authors--UTMB graduate student Bradley S. Schneider, senior research associate Dana Vanlandingham, research assistant Kimberly A. Klingler and Ernest A. Gould of the United Kingdoms Centre for Ecology and Hydrology--note that although such "non-viremic transmission" (that is, transmission before virus can be detected in the blood) has been observed in cases involving viruses transmitted by ticks, it has never before been documented in a virus carried by mosquitoes.
Jim Kelly | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
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Israeli Butterfly Monitoring Scheme (BMS-IL)
CitationPeer I (2016). Israeli Butterfly Monitoring Scheme (BMS-IL). Version 6.17. ILS - Israeli Lepidopterists’ society. Sampling event dataset https://doi.org/10.15468/q4lynx accessed via GBIF.org on 2018-07-16.
DescriptionThe Israeli Butterfly Monitoring Scheme (BMS-IL). The phenology and abundance estimates derived from the systematic observations performed by BMS-IL observers, serve as excellent indicators for trends in biodiversity, impacts of land-use change, and climate change. Particularly, due to Israel’s geographic location, the migration of desert species serves as a valuable indicator of the impacts of extreme weather events on biodiversity. We share our data openly with the philosophy that transparency and sharing are routes for rapid knowledge generation, cooperation, and capacity building. New collaborations are extremely valuable to make the most of the data. Researchers are more thus encouraged to contact the dataset owners to collaborate on joint analyses and meta-analyses. Note the dataset can also be explored here: http://www.gluecad.com/buttdb/hompage.asp?lng=eng
PurposeThe main objective of the scheme is to provide reliable data for assessing the status and trends in the abundance and phenology of Israel’s butterflies, for both conservation and research purposes.
Study ExtentTransect walks for Butterfly Monitoring Schemes (BMS) in Europe are usually performed weekly, but here in Israel, we conduct them once every two weeks from the beginning of October to the end of June - to account for the longer activity period of butterflies in Israel, and the impacts of climate change.
SamplingTransects are divided into 50m sections and range between 300m and 600m in total length. A transect usually covers a single habitat type. The observer counts the number of every butterfly species that can be seen within a 5m range for each section within the transect. As in all other systematic Butterfly Monitoring Schemes (BMS), the entire transect must always be walked (partial transect walks are not recorded). Furthermore, when no butterfly species are seen for the entire transect, the absence event is still recorded using “-s00” standard notation. Special behaviours such as egg laying or drinking nectar as well as butterfly larvae or eggs can be recorded as well.
Quality ControlEvery reported record is flagged “forApproval”. Record status is changed to “Approved” upon and by expert only. Species out of season or distribution area are flagged for additional verification.
- Selection of location and route of transect is verified by a scientific/principal investigator.
- On the first visit to a new transect, the observer is guided by an expert along the transect. Note each section is numbered and marked.
- Start time and weather conditions are recorded first.
- During transect walk, the observer walks the entire transect and for each section records the count of every butterfly species that can be seen within a 5x5x5m imaginary cube (i.e., within a range of 2.5 m to the sides and 5 m front and above).
- To avoid errors in abundance calculations, individuals that cannot be identified to the species level are registered either by family or as a predefined complex of two or three similar species.
- Butterflies seen outside of the 5m range can be recorded by the observer as ‘Extra’ alongside the code of the nearest section (e.g. 5-extra). However, these extra observations are regarded as sporadic data and are never included in the total number of butterflies observed within the controlled transect area.
- Time ends is recorded.
- If no butterflies are seen for the entire transect, the observer types “non seen” to ensure that the absence event is still registered. Note this is important later on when modelling butterfly flight curves and abundances taking into consideration all observations events.
- Observer logs in to the server and types in the data. Absence events are recorded using “-s00” – standard notation.
- Data is ready for verification by the expert.
Additional infoAll sampling events in this dataset are recorded at the section level. Users who wish to derive butterfly density, please sum up all butterflies observed in all sections within a given transect, and calculate the area as “total-transect-length x 5m”. The total number of sections within a given transect can be found in the measurements or facts data.
- For more information on Israel's butterflies, see Benyamini, D. (2002) A Field Guide to the Butterflies of Israel, Including of Mt. Hermon, Sinai and Jordan (Revised edition). Keter Publishing House, Jerusalem (in Hebrew. Maps and activity periods are illustrated visually). -
- For effective data analysis, see: Dennis, E. B., Freeman, S. N., Brereton, T., Roy, D. B. (2013), Indexing butterfly abundance whilst accounting for missing counts and variability in seasonal pattern. Methods in Ecology and Evolution, 4: 637–645. doi: 10.1111/2041-210X.12053 - https://dx.doi.org/10.1111/2041-210X.12053
- Schmucki, R., G. Pe'er, D. B. Roy, C. Stefanescu, C. Van Swaay, T. H. Oliver, M. Kuusaari, A. Van Strien, L. Ries, J. Settele, M. Musche, J. Carnicer, O. Schweiger, T. Brereton, A. Harpke, J. Heliölä, E. Kühn, and R. Julliard (2015) Regionally informed abundance index for supporting integrative analyses across butterfly monitoring schemes. Journal of Applied Ecology, online first. doi: 10.1111/1365-2664.12561 - https://dx.doi.org/10.1111/1365-2664.12561
- For guidelines on systematic butterfly monitoring see Van Swaay, C., Regan, E., Ling, M., Bozhinovska, E., Fernandez, M., Marini-Filho, O.J., Huertas, B., Phon, C.-K., K”orösi, A., Meerman, J., Pe’er, G., Uehara-Prado, M., Sáfián, S., Sam, L., Shuey, J., Taron, D., Terblanche, R., and Underhill, L. (2015). Guidelines for Standardised Global Butterfly Monitoring. Group on Earth Observations Biodiversity Observation Network, Leipzig, Germany. GEO BON Technical Series 1, 32pp. - http://www.geobon.org/Downloads/reports/GEOBON/2015/Global%20Butterfly%20Monitoring_Web.pdf
position: Database admin
position: Database admin
The Israeli Lepidopterists Society
91 Levona Str.
Telephone: 972 8 9297093
position: Scientific Administrator
Helmholtz Centre for Environmental Research - UFZ
Permoserstr. 15, 04318
administrative point of contact
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It can take years for a researcher to fully understand the diets of a community of herbivorous insects in a tropical rain forest. Now, five Smithsonian scientists are paving a fast track using the DNA found inside the insects' stomachs, potentially turning years of research into months.
This shows six of dozens of rolled leaf beetles collected in Costa Rica for the study. High-quality plant DNA was obtained from the gut contents of these beetles, revealing exactly which Zingiberales plants they had been eating.
Credit: Charles Staines
This method will help scientists understand the ecology and evolution of plant-herbivore interactions more efficiently. Their findings are published in the journal PLOS ONE.
Plants and insects comprise about 50 percent of all known species on Earth, forming the critical foundation of biodiversity in most terrestrial ecosystems. This study focused on 20 species of rolled leaf beetles in Costa Rica and 33 species of flowering plants in the order Zingiberales that the beetles eat and lay eggs on almost exclusively.
Matched against the data gathered from prior direct observation, the information derived from this DNA stomach-content study was nearly identical, yet had taken only fraction of the time and effort.
John Gibbons | EurekAlert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
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112 pages , The Rosen Publishing Group , 2008-08 Examine Gore's background as an environmental activist, his work as a journalist and politician, and about his fight to educate people about global warming and its implications.
We want to encourage the barangays to implement the Ecologic Waste Management Act of the Philippines by initiating plastic waste collection and recycling. Every fourth Sunday our group will receive and sort plastic waste from residents. An industry partner will transform the plastic waste into bricks that can be used for construction. If volunteers can do it with no funds then LGUs should be able ...[Read More]
712 pages , Edward Elgar Publishing , 2017-06-30 This Handbook strives to enhance knowledge and application within sustainability in management education (SiME) across different academic programs, geographic regions and personal/professional contexts. Cross-disciplinary and boundary-spanning, this book focuses on specific themes and is therefore split into four distinct ...[Read More]
The purpose of this booklet is to introduce some basic models in ecology based on differential equations. We assume little mathematical background. Readers need to know what the derivative of a function is.
564 pages , Springer Science & Business Media , 2003-10-31 Phenology is the study of plant and animal life cycle events, which are triggered by environmental changes, especially temperature. Wide ranges of phenomena are included, from first openings of leaf and flower buds, to insect hatchings and return of birds. Each one gives a ready measure of the environment as view...[Read More]
208 pages , Routledge , 2002-03-11 This is the first book-length treatment of the metaphysical foundations of ecological ethics. The author seeks to provide a metaphysical illumination of the fundamental ecological intuitions that we are in some sense `one with' nature and that everything is connected with everything else. Drawing on contemporary cosmology, systems theor...[Read More]
168 pages , Routledge , 2012-09-10 This book covers the general engineering knowledge required by candidates for the Department of Transport's Certificates of Competency in Marine Engineering, Class One and Class Two. The text is updated throughout in this third edition, and new chapters have been added on production of fresh water and on noise and vibration. Reference i...[Read More]
300 pages , Kluwer Academic Publishers , 1992 Law is traditionally conceived as consisting of norms of conduct & power-conferring norms. This conception, however, is unable to account for a variety of elements of modern legal systems that differ significantly from the classical notions. This book concerns the problem of which results of human activity can obtain legal va...[Read More]
557 pages , CRC Press , 2012-12-07 Providing a solid foundation for twenty-first-century scientists and engineers, Data Analysis and Statistics for Geography, Environmental Science, and Engineering guides readers in learning quantitative methodology, including how to implement data analysis methods using open-source software. Given the importance of interdisciplinary wor...[Read More] | <urn:uuid:2f1f0482-0850-4f2d-87c2-7c8b220bb9a8> | 2.59375 | 608 | Content Listing | Science & Tech. | 35.116128 | 95,596,189 |
All living organisms consist of cells that have arisen from other living cells by the process of cell division. In order to ensure that the genetic material is equally and accurately distributed between the two daughter cells during cell division, the DNA fibers must remain in an orderly and closely-packed condition.
At the Max Planck Institute (MPI) of Biochemistry in Martinsried near Munich, scientists have now elucidated how this packaging process works in bacteria. Their studies showed that the SMC protein complex holds DNA together like a clip and thus keeps the genetic material in order.
In each human cell, about two meters of DNA must fit into a cell nucleus that has a diameter of only a few thousandths of a millimeter. Here, the DNA is organized in individual chromosomes. In order to ensure the DNA’s secure transport during cell division, the long and coiled DNA fibers must be tightly packed.
So far, scientists have only a sketchy understanding of this step: The SMC protein complexes play a key role in this process. They consist of two arms (SMC) and a bridge (kleisin). Together, they form a ring-like structure. “You can understand how important these protein complexes are when you look at their evolution,” explains Larissa Wilhelm, PhD student at the MPI of Biochemistry. “Structure and operating mode are quite similar in bacteria and humans.”
There are different possibilities as to how the SMC protein complex could pack up DNA. It could for example stick together the different DNA fibers. However, the Max Planck scientists were able to show in bacteria that the SMC protein arms embrace the DNA like a clip, thus enabling the connection of pieces of the DNA that lie wide apart from each other.
In a next step, the members of the research group “Chromosome Organization and Dynamics” want to find out whether the clip either opens for a short period of time in which it embraces already formed DNA loops, or whether the clip first binds to the DNA and then forms DNA loops itself by encasing the DNA.
“Our results could also help to better understand the complex organization of human chromosomes and hereby allow insights into the development of genetic defects such as Trisomy 21” says Stephan Gruber, group leader at the MPI of Biochemistry.
L. Wilhelm, F. Bürmann, A. Minnen, H.-C. Shin, C.P. Toseland, B.-H. Oh, S. Gruber: SMC condensin entraps chromosomal DNA by an ATP hydrolysis dependent loading mechanism in Bacillus subtilis. eLIFE, May 7, 2015.
Dr. Stephan Gruber
Chromosome Organization and Dynamics
Max Planck Institute of Biochemistry
Am Klopferspitz 18
Max Planck Institute of Biochemistry
Am Klopferspitz 18
Phone +49 89 8578-2824
http://www.biochem.mpg.de/en/news - More press release of the Max Planck Institute of Biochemistry
http://www.biochem.mpg.de/gruber - Website of the research group "Chromosome Organization and Dynamics" (Stephan Gruber)
Anja Konschak | Max-Planck-Institut für Biochemie
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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Can anyone elaborate it a bit. Why is it important using these statements?: The method forName is static method of Class,when call it, it can load class from your classpath, Class. When any connection exception occurs, the stacktrace will a lot more verbose, containing the last 16 truncated exchanges with the server. What about this simple way?! If query cannot be rewriten in “multi-values”, rewrite will use multi-queries:
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Search Knowledge Base Login. Thanks man, now I can move on.: You should learn and understand the use of these, they are a very important part of modern event-driven programming, and, in some ways, one of class forname mysql more problematic, as they lead to code which is very non-linear in nature and thus much harder to debug.
When set, overrides serverSslCert. Use the Maven package mysql-connector-java to include the mysql dependency in the POM file for your project.
Driver version Java version 2. The easiest way to do this is to use Class. The driver uses server prepared statements as a standard to communicate with the database since 1. If you don’t expect results to be handled in this amount of time there is a class forname mysql possibility:. Victor Stafusa 6, 8 43 Since MariaDB fforname to be a drop-in replacement for MySql, the driver permits connection froname beginning with “jdbc: First config the class forname mysql.
Secondly, If I write Class.
Pool name that permits identifying threads. These interceptors must implement the org.
e » the Open Tutorials
You first need to ensure you have both java and maven installed on your server before you can build the driver. Post as a guest Name. Permits connecting to the database via Unix domain socket, if the server allows it.
Please class forname mysql, if possible.
Connect to MySQL with JDBC driver
This acts like class loader and load your driver class for you. Permits connecting to the database class forname mysql shared memory, if the server allows it. Set default autocommit value on connection initialization Default: Password for the client certificate keyStore similar to java System property “javax. Phew helped a lot. You might want to solve a bigger problem. Can be used in one of 3 forms: Slf4j is an abstraction for logging, which permits using the logger implementation of your choice.
The default class forname mysql coass Example of configuring “trace” level on driver for logback: Only the first characters corresponding to this options size will be displayed in logs Default: Using Character Sets and Unicode.
Be careful with “trace” level, purpose is to log all exchanges with server. Correctly handle subsecond precision in timestamps feature available with MariaDB 5.
Connect to MySQL with JDBC driver –
Not much left of your question. Here is the Tomcat 7.
If a has been written so that loading it causes an instance to be created and also calls DriverManager. | <urn:uuid:9626e27d-2eb9-4316-9ea8-3b07c3f7cd6a> | 2.546875 | 714 | Q&A Forum | Software Dev. | 55.476415 | 95,596,204 |
posted by Sarah
In reverse osmosis, water flows out of a salt solution until the osmotic pressure of the solution equals the applied pressure. If a pressure of 47.0 bar is applied to seawater, what will be the final concentration of the seawater at 20 °C when reverse osmosis stops?
Assuming that seawater has a total ion concentration (a.k.a colligative molarity) of 1.10 Mc, calculate how many liters of seawater are needed to produce 64.8 L of fresh water at 20 °C with an applied pressure of 47.0 bar.
I got 28.26 for Mc....can someone confirm this answer and help me find the liters for the next part. | <urn:uuid:c295b6a5-e755-4573-9d7d-1d1d3233809c> | 2.515625 | 154 | Q&A Forum | Science & Tech. | 76.461529 | 95,596,211 |
Cooperating Bacteria Isolate Cheaters
News Dec 15, 2015
In natural microbial communities, different bacterial species often exchange nutrients by releasing amino acids and vitamins into their growth environment, thus feeding other bacterial cells. Even though the released nutrients are energetically costly to produce, bacteria benefit from nutrients their bacterial partners provide in return. Hence, this process is a cooperative exchange of metabolites. Scientists at the Max Planck Institute for Chemical Ecology and the Friedrich Schiller University in Jena have shown that bacteria, which do not actively contribute to metabolite production, can be excluded from the cooperative benefits. The research team demonstrated that cooperative cross-feeding interactions that grow on two-dimensional surfaces are protected from being exploited by opportunistic, non-cooperating bacteria. Under these conditions, non-cooperating bacteria are spatially excluded from the exchanged amino acids. This protective effect probably stabilizes cooperative cross-feeding interactions in the long-run.
The Research Group “Experimental Ecology and Evolution” headed by Christian Kost is investigating how cooperative interactions between organisms have evolved. In this context, the scientists study a special type of division of labor that is very common in nature, namely the reciprocal exchange of nutrients among unicellular bacteria. For these tiny organisms it is often advantageous to divide the labor of certain metabolic processes rather than performing all biochemical functions autonomously. Bacteria that engage in this cooperative exchange of nutrients can save a significant amount of energy.
Indeed, in a previous study, the researchers could already demonstrate that this division-of-metabolic-labor can positively affect bacterial growth. In the new study, they addressed the question how such cooperative interactions can persist if non-cooperating bacteria consume amino acids without providing nutrients in return. The evolutionary disadvantage that results for cooperative cells could lead to a collapse of the cross-feeding interaction.
To experimentally verify this possibility, the scientists have monitored co-cultures of cooperating and non-cooperating bacteria. For this, they genetically engineered “cooperators” of two bacterial species that released increased amounts of certain amino acids into their environment. “As a matter of fact, non-cooperators grew better than cooperators in a well-mixed liquid medium, because under these conditions, they had an unrestricted access to the amino acids in the medium. Their growth, however, was considerably reduced when placed on a two-dimensional surface,” said Kost, summarizing the results of the experiments. A more detailed analysis revealed that non-cooperating bacteria could only exist at the very fringe of colonies consisting of cooperating bacteria.
For their study the scientists combined different methods and techniques. The basis formed a new research approach called “synthetic ecology”, in which certain mutations are rationally introduced into bacterial genomes. The resulting bacterial mutants are then co-cultured and their ecological interactions analyzed. In parallel, colleagues at the Friedrich Schiller University from the Department of Bioinformatics developed computer models to simulate these interactions. Finally, chemical analyses using mass spectrometric imaging was instrumental for visualizing the bacterial metabolites. Only the combination of microbiological methods with chemical-analytic approaches and computer simulations enabled the scientists to understand and elucidate this phenomenon.
“The fact that such a simple principle can effectively stabilize such a complex interaction suggests that similar phenomena may play important roles in natural bacterial communities,” Christian Kost states. After all, bacteria occur predominantly in so-called biofilms – these are surface-attached slime layers that consist of many bacterial species. Known examples include bacteria causing dental plaque or bacterial communities that are used in wastewater treatment plants. Moreover, biofilms are highly relevant for medical research: They do not only play important roles for many infectious diseases by protecting bacterial pathogens from antibiotics or the patients’ immune responses, but are also highly problematic when colonizing and spreading on the surfaces of medical implants.
This new study has elucidated that cooperating bacteria form cell clusters and in this way exclude non-cooperating bacteria from their community. “The importance of this mechanism is due to the fact that no complicated or newly-evolved condition, such as the recognition of potential cooperation partners, needs to be fulfilled to effectively stabilize this long-term partnership. Two cooperating bacterial strains and a two-dimensional surface are sufficient for this protective effect to occur”, explains Kost.
The study raises many new exciting questions the researchers plan to address in the future. For example, they are interested in whether or not similar synergistic effects occur when more than two bacterial partners are involved. In their natural habitats, it is likely that more than two bacterial species participate in such cooperative interactions, leading to rather complex interaction networks. Moreover, amino acid-producing bacterial mutants were synthetically generated for this study. Whether also naturally evolved “cooperators” that occur in a habitat like soil show similar dynamics, remains to be verified. Given that bacteria frequently occur in biofilms, cooperative cross-feeding is probably much more widespread than previously thought. Understanding the factors and mechanisms that promote or inhibit bacterial growth could thus provide important clues on how to fight harmful bacteria or to better use beneficial ones.
Rapid and Cost-Effective Instrument that Measures Molecular DynamicsNews
By combining mass spectrometry and thermal desorption, researchers honed a new method to measure excitation and relaxation rates of uracil, the building block of RNA.READ MORE
Getting to Know the Microbes that Drive Climate ChangeNews
A new understanding of the microbes and viruses in the thawing permafrost in Sweden may help scientists better predict the pace of climate change.READ MORE | <urn:uuid:b5182972-8cde-4cc4-a799-32b2d3e87319> | 3.46875 | 1,156 | News Article | Science & Tech. | 4.867047 | 95,596,227 |
In the United Kingdom the Meteorological Office is collaborating with the Central Electricity Research Laboratories (CERL) in a study of the long-range transport of pollutants over the North Sea. For these experiments the plume from Eggborough power station in South Yorkshire is “labelled” with sulphur hexafluoride so that it can be uniquely identified. The movement of the plume is predicted by a numerical trajectory model, and the Hercules aircraft of the Meteorological Research Flight, Farnborough is used to intercept and sample the gases at selected distances downwind. The usual meteorological, turbulence and cloud physics instrumentation on the aircraft (Nicholls, 1978) has been augmented by chemical sampling equipment (Crabtree and Marsh, 1981) in order to measure, on a time-scale short enough to reveal the detailed structure of the plume, the concentrations of the tracer gas, sulphur and nitrogen compounds, and ozone. Several flights have been carried out so far, including one experiment in which the same portion of the plume was sampled on two successive days. Plumes have been detected at distances up to more than 600 kilometres from the source.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Studies of Plume Transport and Dispersion Over Distances of Travel up to Several Hundred Kilometres
- Springer US
Neuer Inhalt/© ITandMEDIA, Product Lifecycle Management/© Eisenhans | vege | Fotolia | <urn:uuid:b20ee09d-b5d2-47ce-88b5-8b7be526b7b0> | 3 | 310 | Knowledge Article | Science & Tech. | 7.953469 | 95,596,245 |
SCIENCE - TECHNOLOGY - NATURE
'RADICAL' MUSLIMS? THE HISTORY OF SALAFISTS
This article was originally published at
50,000 YEAR OLD LIFEFORMS WERE FOUND IN AN ABANDONED MINE
NASA Astrobiologist Penelope Boston has uncovered 50,000 year old microscopic organisms in the deep and extreme Naica caves. This discovery could, alongside existing knowledge and researcher, allow scientists to better understand early life on Earth and possible life on other planets.
FACTS ABOUT VENUS FLYTRAPS
Unlike most plants, Venus flytraps are carnivorous, which means they eat meat. Charles Darwin wrote in his 1875 publication, "Insectivorous Plants," that the Venus flytrap is "one of the most wonderful [plants] in the world.
DINOSAURS MAKE AN OPERATIC DEBUT AT MUSEUM WITH 'RHODA AND THE FOSSIL HUNT'
At the American Museum of Natural History (AMNH) in New York City, the dinosaur halls offer a window into a world millions of years ago, with mounted fossil skeletons representing massive extinct animals such as Tyrannosaurus rex and the long-necked Apatosaurus.
3,000-YEAR-OLD CHILD FOOTPRINTS FOUND AT SITE OF ANCIENT EGYPTIAN PALACE
Mysterious, 3,000-year-old footprints of ancient Egyptian children have emerged alongside rare painting fragments, at what appears to be the site of a royal palace or temple.
FACTS ABOUT VANADIUM
Vanadium is a medium-hard, steel-blue metal. Although a lesser-known metal, it is quite valuable in the manufacturing industry due to its malleable, ductile and corrosion-resistant qualities.
ELON MUSK SET TO REVEAL A BREAKING SPACEX ANNOUNCEMENT
At 4pm EST (1pm GMT), Elon Musk is going to reveal new information about his commercial spaceflight company.
COULD A SPACECRAFT FLY TO THE SUN?
Humans have sent spacecraft to the moon, the red planet Mars and even distant interstellar space, but could we send a spaceship to the scorching sun?
The answer is yes, and it's happening soon.
In 2018, NASA plans to launch the Solar Probe Plus mission to the sun.
TWO NEW NASA INSTITUTES WILL PREPARE US TO LIVE AWAY FROM EARTH
NASA has decided to fund two Space Technology Research Institutes (STRIs) to help prepare humanity to colonize other parts of the universe. Experts like Elon Musk and Stephen Hawking agree that humanity must venture to live outside of our planet.
CASPIAN SEA: LARGEST INLAND BODY OF WATER
The Caspian Sea is the Earth's largest inland body of water. It lies at the junction of Europe and Asia, with the Caucasus Mountains to the west and the steppes of Central Asia to the east. | <urn:uuid:e27a8dc6-0d91-470e-a4fc-396dc07ea870> | 3.078125 | 634 | Content Listing | Science & Tech. | 38.581068 | 95,596,258 |
Regular intrinsic brightness variations observed in many stars are caused by pulsations. These pulsations provide information on the global and structural parameters of the star. The pulsation periods range from seconds to years, depending on the compactness of the star and properties of the matter that forms its outer layers. Here, we report the discovery of more than a dozen previously unknown short-period variable stars: blue large-amplitude pulsators. These objects show very regular brightness variations with periods in the range of 20–40 min and amplitudes of 0.2–0.4 mag in the optical passbands. The phased light curves have a characteristic sawtooth shape, similar to the shape of classical Cepheids and RR Lyrae-type stars pulsating in the fundamental mode. The objects are significantly bluer than main-sequence stars observed in the same fields, which indicates that all of them are hot stars. Follow-up spectroscopy confirms a high surface temperature of about 30,000 K. Temperature and colour changes over the cycle prove the pulsational nature of the variables. However, large-amplitude pulsations at such short periods are not observed in any known type of stars, including hot objects. Long-term photometric observations show that the variable stars are very stable over time. Derived rates of period change are of the order of 10−7 per year and, in most cases, they are positive. According to pulsation theory, such large-amplitude oscillations may occur in evolved low-mass stars that have inflated helium-enriched envelopes. The evolutionary path that could lead to such stellar configurations remains unknown.
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We thank M. Kubiak and G. Pietrzyński, former members of the OGLE team, for their contribution to the collection of the OGLE photometric data over the past years. The OGLE project has received funding from the National Science Centre, Poland (grant number MAESTRO 2014/14/A/ST9/00121 to A.U.). M.L. acknowledges support from the Alexander von Humboldt Foundation. The Las Campanas Observatory, which hosts the Warsaw Telescope, Swope Telescope and Magellan Telescopes, is operated by the Carnegie Institution for Science. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the NSF (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil).
Supplementary Figures 1–2 | <urn:uuid:ff748b1f-4ff2-475c-9a1f-1ef8940166b6> | 2.75 | 651 | Truncated | Science & Tech. | 38.573536 | 95,596,260 |
What can prehistory tell us about the origins of modern birds? Bhart-Anjan Bhullar, from Yale University, talks with us about how the discovery of a 95 million year old Ichthyornis fossil in 2014 revealed some unexpected insights into the minds — and mouths — of modern birds. Anjan’s article, “Complete Ichthyornis skull illuminates mosaic assembly of the avian head” was published on May 2, 2018 in Nature with Dan Field six other researchers.
Websites and other resources
Neurocranium of the newly discovered Ichthyornis (21.2 MB)
- “Evolutionary insights from an ancient bird” (commentary by Kevin Padian on Anjan’s study)
- “Dinosaur-Era Bird Found With Shockingly Intact Skull” (National Geographic discussion with Dan Field)
- Extended data and additional figures
- Supplement information (including multiple videos)
- Othneil Charles Marsh biography
- Related: “Scientists have successfully replicated the molecular processes that led from dinosaur snouts to the first bird beaks” (Yale Department of Geology & Geophysics)
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Hosts / Producers
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How to Cite
Watkins, R., Leigh, D., & Bhullar, B.-A.. (2018, July 10). Parsing Science – Prehistoric origins of birds. figshare. https://doi.org/10.6084/m9.figshare.6799199.v1
What’s The Angle? by Shane Ivers | <urn:uuid:a5882420-d957-443e-b325-d0a111090b71> | 3.3125 | 397 | Truncated | Science & Tech. | 50.192955 | 95,596,308 |
The Appalachian Mountains, also known as the Appalachians, are a system of mountains in eastern North America. They run from central Alabama to the New England region of the northeast United States and extend into sections of Quebec, New Brunswick, and Newfoundland in Canada. The mountain range forms a natural barrier between the eastern coastal regions and the interior lowlands of northeastern America. The forests of the Appalachians sustain a variety of ecosystems and native biological diversity. The environmental effects and ecosystem functions and services associated with the Appalachians have long been the focus of scientific research in understanding the mountain range as a unique geographic entity and in comparison with different spatial contexts for providing a regional reference and validation.
The Appalachian Trail is an iconic footpath that traverses high-elevation ridges of the Appalachian Mountains. The trail extends over 3500 km across 14 states in the eastern United States from Springer Mountain in northern Georgia to Mount Katahdin in central Maine. The gradients in elevation, latitude, and moisture sustain a rich biological assemblage of temperate zone forest species. The north-south alignment of the Appalachian Trail corridor represents a cross-section mega-transect of the eastern U.S. forests and alpine areas and provides a barometer for early detection of undesirable changes in the natural resources, such as development encroachment, acid precipitation, invasions of exotic species, and climate change impacts.1,2
Climate change studies reveal the effects of global warming on the growing season of terrestrial vegetation at middle and high latitudes.3,4 Over the 20th century, the global average surface temperature increased . Observable warming occurred between 1976 and 2000, and temperatures are projected to increase5,6 by 1.4°C to 5.8°C from 1990 to 2100. Tracking variations in landscape dynamics provides an understanding of the changing environment, the impacts and threats caused by changes, and the likely trends in the future for natural resources and associated ecosystems.7 Time series remote sensing data provide necessary observations in revealing patterns of landscape dynamics either by abrupt change or gradual variations.
The normalized difference vegetation index (NDVI) has been effectively used for monitoring vegetation dynamics. Consistent and long time-series NDVI data are important for analysis of vegetation responses to global change in terrestrial ecosystems.8 The Global Inventory Monitoring and Modeling Studies (GIMMS) NDVI dataset derived from Advanced Very High Resolution Radiometer (AVHRR) has been broadly used for studying vegetation activity on regional and global scales.
Phenology studies have long been reported in different domains, such as climate change.9 biodiversity,10 wildlife ecology,11 snow dynamics,12 fire effects,13 and crops.14 Land surface phenology (LSP) is one of the measures of landscape dynamics. It reflects the response of vegetated surfaces to seasonal and annual changes in the climatic and hydrologic cycle. LSP is strongly linked to climatic factors.15 It has been broadly studied in the context of ecosystem responses to climate change16 and for monitoring and understanding global change in vegetation lifecycle events. Because of spatial resolution of remote sensing data, LSP is described as an indicator of mixtures of land covers and is distinct from traditional notion of species-centric phenology, such as seasonal flowering or budburst.17,18 Because LSP is based on remote sensing observations at regional and global scales, it serves as a key biological indicator for detecting the response of terrestrial ecosystems to climatic variation.
LSP metrics are primarily based on time series images of vegetation indices from optical sensors such as AVHRR, spot-vegetation (VGT), and moderate resolution imaging spectroradiometer (MODIS). These metrics typically retrieve the time of the onset of greenness as the start of the season (SOS), onset of senescence or time of end of greenness as the end of the season (EOS), timing of the maximum of the growing season by peak vegetation indices, and the length of growing season (LOS) or duration of greenness. An increasing number of studies have reported the shifts in timing and length of the growing season based on phenology, satellite data, and climatological studies.6
Net primary production (NPP) plays an important role in the Earth surface system’s health19 and the terrestrial carbon cycle.20,21 NPP and its response to climate change have been the focus of global change research.22 Studies have been conducted based on historical datasets.23184.108.40.206.220.127.116.11.–32 Recent climatic changes have enhanced plant growth in northern middle and high latitudes.31 Various NPP models have been developed to analyze NPP response to climate change.318.104.22.168.22.214.171.124.41.–42 Regional scale carbon cycle processes and climate patterns provide indications of potential responses and feedback to climate change.43
Other studies showed that temperatures across the northeastern United States have been increasing steadily since the 1970s. A wide range of indicators in the Northeast have already been observed to be responsive to the changes, which in turn have the potential to impact urban and rural life, agriculture, industry, tourism, and natural ecosystems.44 The U.S. Global Change Research Program reported that the annual average temperature in the Northeast has increased by 1.1°C, with winter temperatures rising twice that much, since 1970. At the same time, warming has resulted in many other climate-related changes, including more frequent days with temperatures above 32.2°C, longer growing seasons, increased heavy precipitation, more winter precipitation falling as rain instead of snow, reduced snowpack, earlier breakup of winter ice on lakes and rivers, and earlier spring snowmelt resulting in earlier peak river flows and rising sea surface temperatures and sea levels.45 Projections along the Appalachian Trail corridor area showed a steady temperature increase ranging from 2°C to 6°C by the end of the 21st century. Precipitation, however, did not show any significant trend or decadal variation.46
Therefore, the objective of this study is to investigate the patterns and trends of NDVI, LSP, and NPP of the Appalachian Mountains regions and make comparisons of those variables with different scales of spatial contexts using time series GIMMS and Global Production Efficiency Model (GloPEM) datasets.37,47
Materials and Methods
The selected Appalachian Mountains regions consist of four provinces of ecoregions in the United States and Canada covering a latitudinal range between and and in area (Fig. 1). The provinces of ecoregions include the Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province, the Eastern Broadleaf Forest Province, and the Central Appalachian Broadleaf Forest-Coniferous Forest-Meadow Province in the United States48 and a section of the Eastern Canadian Forests.
The Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province has a modified continental climatic regime with long, cold winters and warm summers. Annual precipitation is evenly distributed. The landscape is mountainous and was previously glaciated. Forest vegetation is a transition between boreal on the north and broadleaf deciduous to the south. The Eastern Broadleaf Forest Province has a continental-type climate of cold winters and warm summers. Annual precipitation is greater during the summer. Topography is variable, ranging from plains to low hills of low relief along the Atlantic coast. Interior areas are high hills to semi-mountainous, parts of which were glaciated. Vegetation is characterized by tall, cold-deciduous broadleaf forests. The Central Appalachian Broadleaf Forest-Coniferous Forest-Meadow Province is a moderately dissected plateau of irregular plains and open hills. Geologic formations are mostly marine deposits of limestones, shales, and sandstone. The existing land cover type is mainly agricultural and urban. Small areas of natural cover types remain, consisting of forests of oak-hickory, maple-beech-birch, and oak-gum-cypress cover types. The Eastern Canadian Forests are characterized by forested land in eastern Quebec, much of Newfoundland, the highlands of New Brunswick, and Cape Breton Island, Nova Scotia. The climate ranges from high and mid-boreal and perhumid mid-boreal to Oceanic, Atlantic, and maritime mid-boreal. Summers are generally cool, with average temperatures ranging from 8.5°C in the north to 14.5°C in the south. Winter temperatures vary according to the proximity to the ocean and continental landmass.
In order to reveal the differences and similarities of NDVI, SOS, and NPP in the Appalachian Mountains regions, we compared the variables in different spatial scales with North America and the Appalachian Trail corridor area (Fig. 1), and in different latitudinal ranges from 30°N to 40°N and 40°N to 50°N in North America.
GIMMS49 data derived from AVHRR have been used extensively for global-scale vegetation monitoring and detection of trends in vegetation conditions.50 GIMMS data provide global time series NDVI measurements at a spatial resolution of . The data are composited over a period of approximately 15 days with the maximum value compositing (MVC) technique51 to reduce cloud cover and to maintain temporal frequency. The data have been corrected for calibration, view geometry, volcanic aerosols, and other effects not related to vegetation change.49,5253.54.–55 GIMMS data have been used broadly in LSP studies.15,56126.96.36.199.61.62.–63 The GIMMS data were fitted yearly with a Gaussian function to generate smoothed data for each of the 25 years from 1982 to 2006. We used monthly composites of GIMMS data to calculate the LSP metrics. The NPP dataset estimated by AVHRR GloPEM was designed to run with both biological and environmental variables derived.37,47 The GloPEM dataset is available from 1981 to 2000 in 10-day periods or a summed annual level. The dataset is derived from AVHRR images at an 8-km resolution from the AVHRR Pathfinder Project.
Land Surface Phenology Metrics
The methods to obtain LSP metrics include thresholds, derivatives, smoothing functions, and fitted models.64 The TIMESAT software program65,66 is among those widely used12,13,6768.69.–70 In order to reduce dropouts or gaps from long time-series data, TIMESAT uses Savitzky-Golay filtering, asymmetrical Gaussian, or double logistic functions for fitting NDVI data.71 The local Savitzky-Golay function can capture subtle and rapid changes in the time series, but it is also sensitive to noise. The asymmetrical Gaussian and double logistic functions are less sensitive to the noise and can derive a better description of the beginnings and endings of the seasons.65,72 In this study, we adopted the asymmetrical Gaussian approach:2,71
In order to make comparisons of LSP in different scales, we employed the GIMMS and the phenology data from the USDA Forest Service that possess 231-m spatial resolution and cover the time period from 2003 to 2006. We then determined the parameter. The SOS is defined as the time for which the left edge has increased to 20% (seasonal amplitude from minimum NDVI to maximum NDVI) measured from the left minimum NDVI. The EOS is defined as the time for which the right edge has decreased to 20% (seasonal amplitude from minimum NDVI to maximum NDVI) measured from the right minimum NDVI. The LOS is the time period measured in days from the SOS to the EOS. We built the smooth time series of NDVI from TIMESAT. We derived the LSP metrics based on and adopted the adaptation strength of 2.0, no spike filtering, and amplitude. We calculated the SOS and EOS for each year and obtained LOS as the difference between SOS and EOS in each grid cell. In this paper, we analyzed the spatial and temporal variation of LOS in the study areas. We used the nonparametric Mann-Kendall test for testing the presence of the monotonic increasing or decreasing trends and the Sen’s method for estimating the slope of linear trends of annual peak values of NDVI, LOS, and NPP.
Spatial Pattern Of NDVI, LSP, and NPP
Figure 2 illustrates spatial patterns of the mean value of peak NDVI, LSP, NPP, Temperature, Precipitation, and Land Cover. The peak NDVI, LSP, and NPP represent the maximum value of the year and were obtained using the MVC method. The mean peak NDVI, LSP, and NPP were obtained similarly. Land cover types were considered in obtaining the spatial variation of NDVI, as shown in Fig. 2(a) and 2(f). For example, forests are mainly distributed in humid climatic zones of the Appalachian Mountains73 and therefore possess high NDVI values. At pixel scale, the data illustrate spatial dynamics of LOS of the Appalachian Mountains between 1982 and 2006. The spatial variation indicates that the average LOS varied from 144 to 262 days, and extended LOS was observed in low-latitude areas, as shown in Fig. 2(b). The patterns indicate that LOS increased from northeast to southwest in these areas. Spatial pattern reveals that LOS was more responsive to the variation of temperature [Fig. 2(d)] than to precipitation [Fig. 2(e)]. Annual mean NPP ranged from 450 to [Fig. 2(c)] in the Appalachian Mountains over the 20 years from 1991 to 2000. NPP values reflected the latitudinal effects from southwest to northeast at 34°N to 40°N, 40°N to 45°N, and 45°N to 50°N. Areas with low NPP were found in the high-latitude regions, consistent with the changes in temperature [Fig. 2(d)]. The pattern of temperature variation showed a decreasing trend from southwest to northeast. The mean temperature showed high values from 34°N to 40°N, medium values from 40°N to 45° N, and low values from 45°N to 50°N. The precipitation was highest with in the low-latitude regions, as shown in Fig. 2(e). In the southwestern region, the NPP, temperature, and precipitation measures were higher than those in other regions. A combination of higher temperature and precipitation contributes to high NPP in the southwestern region of the Appalachian Mountains.
Trends Of NDVI, LSP, and NPP
The trend of NDVI in the Appalachian Mountains regions varied from to 0.0056 units. The declining trends of peak NDVI occurred in the Appalachian Mountains, particularly in the central regions [Fig. 3(a)]. Only the section area within the Eastern Canadian Forests showed increasing trends of peak NDVI.
Spatial variations in LOS trends indicate that LOS varied between days (decreasing) to 2.97 days (increasing) per year from 1982 to 2006 over the Appalachian Mountains regions [Fig. 3(b)]. The decreasing trends () were mainly found in the Central Appalachian Broadleaf Forest-Coniferous Forest-Meadow Province and the Eastern Canadian Forests. Positive LOS trends mainly occurred in the Adirondack-New England Mixed Forest-Coniferous Forest-Alpine Meadow Province, as shown in Fig. 3(b).
We calculated the trends in NPP at the pixel level (8 km) from 1981 to 2000 using linear least squares. These calculations are shown in Fig. 3(c). Positive and negative NPP trends were found across the Appalachian Mountains regions. Observable increases occurred in the Central Appalachian Broadleaf Forest-Coniferous Forest-Meadow Province and the Northeastern Mixed Forest Province. A decrease in NPP occurred in the northeast, and an increased trend was observed in the southwest of the Appalachian Mountains.
Comparison of Appalachian Mountains with Different Spatial Contexts
The NDVI data were calculated for vegetated area only. For Figs. 4Fig. 5–6, the straight lines were generated using the method of linear least squares. Significant decrease in annual peak NDVI was observed in the Appalachian Mountains, as well as the Appalachian Trail corridor area (Fig. 4). The average slope in the Appalachian Mountains was a (, ) NDVI unit decrease per year during the 25 years from 1982 to 2006. For the Appalachian Trail corridor area, the average slope was a (, ) NDVI unit decrease per year over the 25 years. However, there was no observable trend in North America or in the selected latitudinal ranges from 30°N to 40°N and from 40°N to 50°N (Fig. 4 and Table 1).
The parameters of NDVI, LOS, and NPP
|Parameter||30°N–40°N||40°N–50°N||North America||Appalachian Mountains||Appalachian Trail Corridor|
The prolonged LOS was over the entire Appalachian Mountains, in latitudinal zone from 40°N to 50°N, in North America, and in the Appalachian Trail corridor area. However, the LOS trend was shortened by in latitudes from 30°N to 40°N. Although there was no indication of a significant trend in LOS in any region during the study time periods, abnormal values in some years (e.g., 1998 and 1999) were observable against the calculated mean values and are shown in Fig. 5.
We calculated the annual mean NPP values for the Appalachian Mountains, North America, and the Appalachian Trail corridor area (Fig. 6 and Table 1). The average NPP values were 1,008, 797, 597, 802, and , in the 30°N–40°N range, the 40–50°N range, North America, the Appalachian Mountains, and the Appalachian Trail corridor area, respectively. The increasing trend in NPP was observed for all the regions during the 20-year period (Fig. 6). The NPP increased (, ) from 1982 to 2006 in Appalachian Mountains. The trends in NPP showed an increase of (, ) in the 30°N–40°N range, (, ) in the 40°N–50°N range, (, ) in North America, and (, ) in the Appalachian Trail corridor.
Conclusions and Discussion
This study revealed the spatial and temporal variations and trends in landscape dynamics, LSP, and NPP in the study area. The comparisons examined the Appalachian Mountains as a unique geographic entity and their topographic and elevation effects in the spatial context. Our conclusions are as follows.
The peak NDVI values decreased significantly in the Appalachian Mountains and the Appalachian Trail corridor area (Fig. 4). Both trends possessed higher negative slopes than those in the 30°N–40°N and 40°N–50°N latitudinal zones and North America. The mean peak NDVI values were 0.86 in the Appalachian Mountains and 0.84 in the Appalachian Trail corridor, higher than those of North America. Other studies have suggested that the average annual peak NDVI presented a declining trend over many protected areas in North America.50 Given that neither temperature nor precipitation showed a correlation with NDVI, this may imply that the observed decrease in NDVI was mainly driven by the combination of urban expansion and outbreaks of hemlock wooly adelgids (Adelges tsugae)7475.–76 and other insect pests. Consistent with the patterns observed in the AVHRR GIMMS data along the Appalachian Trail corridor, analyses using other types of remote sensing data have shown a decrease in forest cover in the eastern U.S., mainly due to the growth of urban areas since the 1970s.7,7778.–79
There are different results from different methods for calculation of LSP parameters.64 For example, the results from four methods were very much different. The SOS calculated by the moving average method was the lowest, and the EOS value was the highest, but the derivative method delivered the highest SOS value and the lowest EOS value.
A reported LSP study suggested that the EOS in North America was delayed by 8.1 days per decade from 1982 to 1999 and by 1.3 days per decade from 2000 to 2008.80 Another study reported that SOS advanced by approximately 8 days, EOS was delayed by 4 days, and LOS increased by 12 days in North America from 1982 to 1999.81 The results of this study suggested that LOS in the Appalachian Mountains advanced 7.5 days from 1982 to 2006. The longest annual mean LOS value (233 days) was observed in the Appalachian Trail corridor area, and the second longest LOS value (227 days) was observed in the Appalachian Mountains regions. The mean LOS in the latitudinal range between 40°N and 50°N increased by (, ) from 1982 to 2006; that increase was higher than those in other regions. The overall trend along the Appalachian Mountains, despite local variations, agreed with broader patterns obtained for the Northern Hemisphere and North America. The local variations were caused by topographic and elevation effects, as well as associated land cover types and ecosystems.
To further understand the effect of elevation, we divided the LOS into 20 categories from to 2,025 m. We found that the LOS was shortened by 1.2 days (, ) for every 100-m increase in elevation. The prolonged LOS was mainly attributed to delayed EOS. This study concluded that the variations and trends of LSP metrics in the Appalachian Mountains were comparable to those obtained for the Appalachian Trail corridor area.82 The LOS anomalies in 1987, 1994, and 1998 followed the pattern of warm and cold episodes based on a threshold of for the Oceanic Niño Index (ONI). The reversed LOS patterns correspond to El Niño in 1997 to 1998 and La Niña in 1999 to 2000 events.83 This indicates that LOS is sensitive to climate variations.
NPP modeling studies have documented that terrestrial photosynthetic activity has increased over the past two to three decades in the middle and high latitudes in the Northern Hemisphere.2829.–30,32,84 The mean annual NPP in North America (north of 22°N) was reported as , increasing by (significant at the 99% level) from 1982 to 1998.28 The results from this study illustrated significant increasing trends of NPP from 1981 to 2000 in all the study regions. The NPP in the Appalachian Mountains increased by (, ), a smaller rate than that for North America (, , ). The largest annual mean NPP value () and the largest trend increase (, , ) were observed in the latitudinal range between 30°N and 40°N. The mean NPP in the Appalachian Trail corridor area increased by (, ), which was larger than that for North America and smaller than that for the Appalachian Mountains regions.
While prolonged LOS and increasing trends of annual NPP were observed in the Appalachian Mountains and the Appalachian Trail corridor, peak NDVI showed a decreasing trend. There are many factors that could affect the change of NDVI, LOS, and NPP in different spatial contexts of the study areas. The similar pattern of variations and trends between the Appalachian Trail corridor area and the Appalachian Mountains regions suggested that the Appalachian Trail corridor area can serve as a mega-transect to reflect such variations and trends of the Appalachian Mountains regions.
This study was funded by NASA Science Mission Directorate (ROSES-2008) Decision Support through Earth Science Research Results under the project “A Decision Support System for Monitoring, Reporting and Forecasting Ecological Conditions of the Appalachian National Scenic Trail” (Grant NNX09AV82G). In particular, the authors thank the contributions of those who are on the project team to develop the decision support system: Peter August, Roland Duhaime, Christopher Damon, John Clark, Fu Luo, Charles LaBash, and Peter Paton from the University of Rhode Island; Forrest Melton, Hirofumi Hashimoto, Samuel Hiatt, and Ramakrishna Nemani from the NASA Ames Research Center; Fred Dieffenbach, Matt Robison, Casey Reese, and Brian Mitchell from the National Park Service; Ken Stolte from the USDA Forest Service; Glenn Holcomb and Marcia McNiff from the USGS; and Paul Mitchell from the Appalachian Trail Conservancy. Dr. William Hargrove of the Eastern Forest Environmental Threat Assessment Center, USDA Forest Service, provided the 231-m spatial resolution phenology data. The authors wish to express their sincere appreciation for the critiques and suggestions from anonymous reviewers that helped improve the quality of the manuscript.
Yeqiao Wang received his MS and PhD in natural resources management and engineering from the University of Connecticut in 1992 and 1995, respectively. He is currently a professor of terrestrial remote sensing at the Department of Natural Resources Science, University of Rhode Island, USA.
Jianjun Zhao received his BS in 2007 from the School of Urban and Environmental Sciences, Northeast Normal University, Changchun, China, where he is currently working toward a PhD in remote sensing. He is also currently a visiting PhD student at the Department of Natural Resource Science, University of Rhode Island, USA. His research interests are remote sensing of terrestrial ecosystems, data processing, and applications.
Yuyu Zhou received his PhD in environmental sciences from the University of Rhode Island, where he studied land use and land cover change and its impact on the environment. He then worked as a postdoctoral research associate at Purdue University and performed high-resolution fossil-fuel emissions modeling studies at national and city scales. Currently, he is a scientist conducting global climate change research at the Pacific Northwest National Laboratory as part of a diverse, interdisciplinary group of scientists who develop and apply an integrated global land use-energy-economy model.
Hongyan Zhang received his PhD from the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences. He is currently a professor in GIS and remote sensing with the School of Urban and Environmental Sciences, Northeast Normal University, Changchun, China. His main research interests are applications of GIS and remote sensing and geoinformatic presentation. | <urn:uuid:1c76699b-9b95-4177-b500-b8f0b8fdb16f> | 4.15625 | 5,420 | Academic Writing | Science & Tech. | 45.380143 | 95,596,309 |
- Research news
- Open Access
Skim before you fly
© BioMed Central Ltd 2000
Published: 16 November 2000
How does gradual evolutionary change come up with a complex trait such as flying? One possible intermediate state for insects is surface-skimming, in which the insect's weight is borne by water, meaning that the wings must deal only with generating forward motion. A limited analysis suggested, however, that present-day surface skimmers were evolutionary latecomers, and had lost their previous ability to fly. In the November 21 Proceedings of the National Academy of Sciences, Thomas et al. analyze skimming behaviors and rRNA gene sequences of 34 stonefly species and come to the opposite conclusion (Proc. Natl. Acad. Sci. USA 2000, 97:13178-13183). This more extensive analysis reveals that the number of costal cross veins in the wings has increased during species radiation, allowing skimming to expand to flying. This evolutionary trajectory may or may hold for insects as a whole. It is at least consistent with a growing body of anatomical and molecular evidence that wings evolved from the moveable gillsof aquatic ancestors.
- Proceedings of the National Academy of Sciences, [http://www.pnas.org/]
- Movie of gill flapping, [http://www.bio.psu.edu/people/faculty/marden/movies/gillflap.mov] | <urn:uuid:68db4e1b-bee3-47c9-9e90-17897dc31761> | 3.34375 | 297 | Truncated | Science & Tech. | 47.869573 | 95,596,332 |
posted by Shellby
A 100g sample of water at 90 degrees celsius is added to a 100g sample of water at 10 degrees celsius.
The final temperature of the water is which of the following:
a) between 50 degrees celsius and 90 degrees celsius
b) 50 degrees celsius
c) between 10 degrees celsius
This is a practice problem so i know that the answer is b) 50 degrees celsius, but i am confused on how to find that answer.
Since these are the same masses, you can simply take the average of 90 and 10.
(90+10)/2 = 50. If they are not the same mass it is a little more complicated than that but all of these can be solved the same way.
heat gained by cool water + heat lost by warm water = 0
[mass cool H2O x specific heat H2O x (Tfinal-Tinitial)] + [mass warm H2O x specific heat H2O x (Tfinal-Tinitial)] = 0
Solve for Tfinal. | <urn:uuid:4d611676-1be4-478a-ad5f-ea96f2a6b920> | 3.375 | 223 | Q&A Forum | Science & Tech. | 69.265802 | 95,596,338 |
Celestial mechanics, the study of motions of celestial bodies, together with spherical astronomy, was the main branch of astronomy until the end of the 19th century, when astrophysics began to evolve rapidly. The primary task of classical celestial mechanics was to explain and predict the motions of planets and their satellites. Several empirical models, like epicycles and Kepler’s law, had been employed to describe these motions. But none of these models explained why the planets moved the way they did. It was only in the 1680’s that a simple explanation was found for all these motions — Newton’s law of universal gravitation. In this chapter, we will derive some properties of orbital motion. The physics we need for this is simple indeed, just Newton’s laws. (For a review, see *Newton’s Laws, p. 153.
KeywordsOrbital Element Radius Vector Orbit Determination Orbital Plane Celestial Mechanics
Unable to display preview. Download preview PDF. | <urn:uuid:cd0f6b6f-7063-49b9-a894-958de7ac6859> | 3.65625 | 205 | Truncated | Science & Tech. | 45.948377 | 95,596,351 |
Sea creatures confused by harbour lights 海洋生物被港口人工照明搞的晕头转向
媒体英语会带大家一起学习 BBC 撰稿人在报道世界大事时常用到的单词和短语。
一项发表在皇家学会报告《生物学报》期刊的研究称海港的人工照明诱使海洋生物靠近并从而损害停靠的船舶。以下是 Rebecca Morelle 的报道。
With harbours operating around the clock, night time lighting is an essential feature for the shipping industry. But this study suggests it could have costly consequences.
Scientists at the University of Exeter in the UK say that artificial illumination is confusing some small clinging sea creatures. Some of these, such as keel worms, can cause damage when they attach to ships' hulls - and the bright lights seem to be drawing them in.
An influx of these animals can slow down boats and they are expensive to remove.
The light pollution is also having an effect on shade-loving sea creatures such as sponges, causing them to seek a home in darker waters.
The researchers are concerned that this is disrupting the delicate balance of these marine communities. | <urn:uuid:a9baebfc-14c1-422d-84ae-004ab48a2866> | 2.6875 | 388 | News Article | Science & Tech. | 48.48 | 95,596,353 |
Their achievement currently represents the shortest artificial light pulse that has been reported in a refereed journal. Shining this ultrashort light pulse on atoms and molecules can reveal new details of their inner workings—providing benefits to fundamental science as well as potential industrial applications such as better controlling chemical reactions. Working at Italy's National Laboratory for Ultrafast and Ultraintense Optical Science in Milan (as well as laboratories in Padua and Naples), the researchers believe that their current technique will allow them to create even shorter pulses well below 100 attoseconds. Results will be presented in Baltimore at CLEO/QELS, May 6 – May 11.
Whereas humans perceive the world in terms of seconds and minutes, the electrons in atoms and molecules often perform actions on attosecond time scales. How short is this? 130 attoseconds is to one second as a second is to approximately 243 million years—roughly the time that has passed since the first dinosaurs walked the Earth. Aiming a human-made attosecond-scale light pulse on atoms and molecules can trigger new effects in electrons—which are responsible for all chemical reactions—and provide new details on how they work.
In previous experiments, longer pulses, in the higher hundreds of attoseconds, have been created, and the general process is the same. An intense infrared laser strikes a jet of gas, usually argon or neon. The laser’s powerful electric fields rock the electrons back and forth, causing them to release a train of attosecond pulses consisting of high-energy photons in the extreme ultraviolet or soft x-ray part of the spectrum.
Creating a single isolated attosecond pulse, rather than a train of them, is more complex. To do this, the researchers employ their previously developed technique for delivering intense short (5 femtoseconds, or millionths of a billionth of a second) laser pulses to an argon gas target. They use additional optical techniques (including ones borrowed from the research that won the 2005 Nobel Prize in Physics) for creating and shaping a single attosecond pulse. These isolated attosecond pulses promise to probe electron phenomena such as "wavepackets"—specially tailored electron waves inside atoms and molecules that may help scientists use lasers to change the course of chemical reactions for scientific and practical uses, such as controlling the breaking of bonds in complex molecules for medical and pharmaceutical applications.
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Materials Sciences
20.07.2018 | Physics and Astronomy
20.07.2018 | Materials Sciences | <urn:uuid:200847f8-aff4-4e82-8705-f3970ffcdc2c> | 4.125 | 1,061 | Content Listing | Science & Tech. | 35.999065 | 95,596,355 |
sync man page
sync, syncfs — commit filesystem caches to disk
int syncfs(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
sync() causes all pending modifications to filesystem metadata and cached file data to be written to the underlying filesystems.
syncfs() is like sync(), but synchronizes just the filesystem containing file referred to by the open file descriptor fd.
syncfs() returns 0 on success; on error, it returns -1 and sets errno to indicate the error.
sync() is always successful.
syncfs() can fail for at least the following reason:
fd is not a valid file descriptor.
syncfs() first appeared in Linux 2.6.39; library support was added to glibc in version 2.14.
sync(): POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
syncfs() is Linux-specific.
Since glibc 2.2.2, the Linux prototype for sync() is as listed above, following the various standards. In glibc 2.2.1 and earlier, it was "int sync(void)", and sync() always returned 0.
According to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However Linux waits for I/O completions, and thus sync() or syncfs() provide the same guarantees as fsync called on every file in the system or filesystem respectively.
Before version 1.3.20 Linux did not wait for I/O to complete before returning.
sync(1), fdatasync(2), fsync(2)
This page is part of release 4.16 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
bdflush(2), ctrlaltdel(8), fclose(3), fflush(3), fsck.minix(8), fsync(2), guestfish(1), guestfs(3), mke2fs(8), mount(2), mount(8), nbdkit-perl-plugin(3), nbdkit-python-plugin(3), nbdkit-ruby-plugin(3), nfs(5), reboot(2), stress-ng(1), sync(1), sync_file_range(2), syscalls(2), xfs_io(8), xfs_quota(8), zshmodules(1).
The man page syncfs(2) is an alias of sync(2). | <urn:uuid:0772b110-c949-43d1-8dcc-fffcfff5a741> | 2.78125 | 633 | Documentation | Software Dev. | 81.595154 | 95,596,356 |
- Tutorial for Android Developer
Tutorial for Android Developer introduces Android Programming and allows someone with a basic knowledge of programming to start creating Android Applications.
You may also like
Tutorial for Android Developer introduces Android Programming and allows someone with a basic knowledge of
programming to start creating Android Applications. It is a track to cover fundamentals of Android.
It will teach Android programming Paradigm, while creating an Android program.
This app will cover the topics such as Installation, Activities, Layouts, List Views, SQLite, Services
Multimedia and Google Play, Activity, View, Intent, Service, Development, Android SDK, Creating a
project, A project structure, Creating a Virtual Device, Generating jars, User Interface, Views, View
Groups, List view, Spinner, Layouts, Menus ,Alerts/Dialogs, Custom Dialog from XML files, Status-Bar
Notifications, A Bitmap object, drawing the bitmap on a canvas, System APIs, Multi-threading, Regular
Thread, Thread + Handler, synchronize Task etc.
Tutorial for Android Developer encloses many examples with source-codes that are simplified and commented in an elementary way. It not only contains the source-codes, but also it has a feature of ‘Interview
Questions/Answers’ that helps to beat up the Interviews’ complexities.
-SIMPLIFIED TUTORIAL WITH EXAMPLES.
-SYNTAX HIGHLIGHTING WITH PERFECT INDENTING OF SOURCE CODES.
-PROGRAMS TOO HAVE A SAMPLE OUTPUT (IMAGE).
-COPY FEATURE THAT HELPS TO COPY THE SOURCE CODES AND RUN THEM WITHOUT ERRORS.
-SHARE FEATURE HELPS TO SHARE SOURCE CODES WITH FRIENDS OR EVEN MAIL IT YOURSELF.
-A BRIEF EXPLANATION OF CONCEPTS. | <urn:uuid:5a57b03f-e1c3-4a8d-b1ec-59d44b42d7b9> | 3.09375 | 412 | Product Page | Software Dev. | 28.292427 | 95,596,361 |
BCS theory, proposed by Bardeen, Cooper, and Schrieffer (BCS) in 1957, is the first microscopic theory of superconductivity since its discovery in 1911. The theory describes superconductivity as a microscopic effect caused by a condensation of pairs of electrons into a boson-like state. The theory is also used in nuclear physics to describe the pairing interaction between nucleons in an atomic nucleus.
The mid-1950s saw rapid progress in the understanding of superconductivity. It began in the 1948 paper, On the Problem of the Molecular Theory of Superconductivity where Fritz London proposed that the phenomenological London equations may be consequences of the coherence of a quantum state. In 1953, Brian Pippard, motivated by penetration experiments, proposed that this would modify the London equations via a new scale parameter called the coherence length. John Bardeen then argued in the 1955 paper, Theory of the Meissner Effect in Superconductors that such a modification naturally occurs in a theory with an energy gap. The key ingredient was Leon Neil Cooper's calculation of the bound states of electrons subject to an attractive force in his 1956 paper, Bound Electron Pairs in a Degenerate Fermi Gas.
In 1957 Bardeen and Cooper assembled these ingredients and constructed such a theory, the BCS theory, with Robert Schrieffer. The theory was first announced in February 1957 in the letter, Microscopic theory of superconductivity. The demonstration that the phase transition is second order, that it reproduces the Meissner effect and the calculations of specific heats and penetration depths appeared in the July 1957 article, Theory of superconductivity. They received the Nobel Prize in Physics in 1972 for this theory. The 1950 Landau-Ginzburg theory of superconductivity is not cited in either of the BCS papers.
In 1986, high-temperature superconductivity was discovered (i.e. superconductivity at temperatures considerably above the previous limit of about 30 K; up to about 130 K). It is believed that BCS theory alone cannot explain this phenomenon and that other effects are at play. These effects are still not yet fully understood; it is even possible that they also control superconductivity even at low temperatures for some materials.
At sufficiently low temperatures, electrons near the Fermi surface become unstable against the formation of Cooper pairs. Cooper showed such binding will occur in the presence of an attractive potential, no matter how weak. In conventional superconductors, an attraction is generally attributed to an electron-lattice interaction. The BCS theory, however, requires only that the potential be attractive, regardless of its origin. In the BCS framework, superconductivity is a macroscopic effect which results from the condensation of Cooper pairs. These have some bosonic properties, while bosons, at sufficiently low temperature, can form a large Bose-Einstein condensate. Superconductivity was simultaneously explained by Nikolay Bogoliubov, by means of the so-called Bogoliubov transformations.
In many superconductors, the attractive interaction between electrons (necessary for pairing) is brought about indirectly by the interaction between the electrons and the vibrating crystal lattice (the phonons). Roughly speaking the picture is the following:
An electron moving through a conductor will attract nearby positive charges in the lattice. This deformation of the lattice causes another electron, with opposite spin, to move into the region of higher positive charge density. The two electrons then become correlated. There are a lot of such electron pairs in a superconductor, so that they overlap very strongly, forming a highly collective condensate. Breaking of one pair results in changing of energies of remained macroscopic number of pairs. If the required energy is higher than the energy provided by kicks from oscillating atoms in the conductor (which is true at low temperatures), then the electrons will stay paired and resist all kicks, thus not experiencing resistance. Thus, the collective behavior of the condensate is a crucial ingredient of superconductivity.
BCS theory starts from the assumption that there is some attraction between electrons, which can overcome the Coulomb repulsion. In most materials (in low temperature superconductors), this attraction is brought about indirectly by the coupling of electrons to the crystal lattice (as explained above). However, the results of BCS theory do not depend on the origin of the attractive interaction. The original results of BCS (discussed below) described an s-wave superconducting state, which is the rule among low-temperature superconductors but is not realized in many unconventional superconductors such as the d-wave high-temperature superconductors. Extensions of BCS theory exist to describe these other cases, although they are insufficient to completely describe the observed features of high-temperature superconductivity.
BCS is able to give an approximation for the quantum-mechanical many-body state of the system of (attractively interacting) electrons inside the metal. This state is now known as the BCS state. In the normal state of a metal, electrons move independently, whereas in the BCS state, they are bound into Cooper pairs by the attractive interaction. The BCS formalism is based on the reduced potential for the electrons attraction. Within this potential, a variational ansatz for the wave function is proposed. This ansatz was later shown to be exact in the dense limit of pairs. Note that the continuous crossover between the dilute and dense regimes of attracting pairs of fermions is still an open problem, which now attracts a lot of attention within the field of ultracold gases.
Successes of the BCS theory
BCS derived several important theoretical predictions that are independent of the details of the interaction, since the quantitative predictions mentioned below hold for any sufficiently weak attraction between the electrons and this last condition is fulfilled for many low temperature superconductors - the so-called weak-coupling case. These have been confirmed in numerous experiments:
- The electrons are bound into Cooper pairs, and these pairs are correlated due to the Pauli exclusion principle for the electrons, from which they are constructed. Therefore, in order to break a pair, one has to change energies of all other pairs. This means there is an energy gap for single-particle excitation, unlike in the normal metal (where the state of an electron can be changed by adding an arbitrarily small amount of energy). This energy gap is highest at low temperatures but vanishes at the transition temperature when superconductivity ceases to exist. The BCS theory gives an expression that shows how the gap grows with the strength of the attractive interaction and the (normal phase) single particle density of states at the Fermi energy. Furthermore, it describes how the density of states is changed on entering the superconducting state, where there are no electronic states any more at the Fermi energy. The energy gap is most directly observed in tunneling experiments and in reflection of microwaves from superconductors.
- BCS theory predicts the dependence of the value of the energy gap E at temperature T on the critical temperature Tc. The ratio between the value of the energy gap at zero temperature and the value of the superconducting transition temperature (expressed in energy units) takes the universal value of 3.5, independent of material. Near the critical temperature the relation asymptotes to
- which is of the form suggested the previous year by M. J. Buckingham in Very High Frequency Absorption in Superconductors based on the fact that the superconducting phase transition is second order, that the superconducting phase has a mass gap and on Blevins, Gordy and Fairbank's experimental results the previous year on the absorption of millimeter waves by superconducting tin.
- Due to the energy gap, the specific heat of the superconductor is suppressed strongly (exponentially) at low temperatures, there being no thermal excitations left. However, before reaching the transition temperature, the specific heat of the superconductor becomes even higher than that of the normal conductor (measured immediately above the transition) and the ratio of these two values is found to be universally given by 2.5.
- BCS theory correctly predicts the Meissner effect, i.e. the expulsion of a magnetic field from the superconductor and the variation of the penetration depth (the extent of the screening currents flowing below the metal's surface) with temperature. This had been demonstrated experimentally by Walther Meissner and Robert Ochsenfeld in their 1933 article Ein neuer Effekt bei Eintritt der Supraleitfähigkeit.
- It also describes the variation of the critical magnetic field (above which the superconductor can no longer expel the field but becomes normal conducting) with temperature. BCS theory relates the value of the critical field at zero temperature to the value of the transition temperature and the density of states at the Fermi energy.
- In its simplest form, BCS gives the superconducting transition temperature in terms of the electron-phonon coupling potential and the Debye cutoff energy:
- Here N(0) is the electronic density of states at the Fermi energy. For more details, see Cooper pairs.
- The BCS theory reproduces the isotope effect, which is the experimental observation that for a given superconducting material, the critical temperature is inversely proportional to the mass of the isotope used in the material. The isotope effect was reported by two groups on the 24th of March 1950, who discovered it independently working with different mercury isotopes, although a few days before publication they learned of each other's results at the ONR conference in Atlanta, Georgia. The two groups are Emanuel Maxwell, who published his results in Isotope Effect in the Superconductivity of Mercury and C. A. Reynolds, B. Serin, W. H. Wright, and L. B. Nesbitt who published their results 10 pages later in Superconductivity of Isotopes of Mercury. The choice of isotope ordinarily has little effect on the electrical properties of a material, but does affect the frequency of lattice vibrations, this effect suggested that superconductivity be related to vibrations of the lattice. This is incorporated into the BCS theory, where lattice vibrations yield the binding energy of electrons in a Cooper pair.
- Ivar Giaever - Nobel Lecture. Nobelprize.org. Retrieved 16 Dec 2010. http://nobelprize.org/nobel_prizes/physics/laureates/1973/giaever-lecture.html
The BCS Papers:
- L. N. Cooper, "Bound Electron Pairs in a Degenerate Fermi Gas", Phys. Rev 104, 1189 - 1190 (1956).
- J. Bardeen, L. N. Cooper, and J. R. Schrieffer, "Microscopic Theory of Superconductivity", Phys. Rev. 106, 162 - 164 (1957).
- J. Bardeen, L. N. Cooper, and J. R. Schrieffer, "Theory of Superconductivity", Phys. Rev. 108, 1175 (1957).
- John Robert Schrieffer, Theory of Superconductivity, (1964), ISBN 0-7382-0120-0
- Michael Tinkham, Introduction to Superconductivity, ISBN 0-4864-3503-2
- Pierre-Gilles de Gennes, Superconductivity of Metals and Alloys, ISBN 0-7382-0101-4.
- Lua error in Module:Citation/CS1 at line 746: Argument map not defined for this variable. | <urn:uuid:dda4cb05-7afc-4803-80e9-5d770a567d38> | 3.796875 | 2,440 | Knowledge Article | Science & Tech. | 32.436662 | 95,596,368 |
Temporal and spatial variability of streamflow
Streamflow occurs as a result of the interaction of the many components of the hydrologic cycle, as shown in Figure 5 of Riggs and Wolman (this volume). The streamflow part of the cycle is driven by precipitation in the form of rain or snow. The complex processes of interception, infiltration, evaporation, and transpiration (Saxton and Shiau, this volume) serve to reduce the amount of water available for runoff at any one time and at any one location. These proceses are influenced by various climatic factors, such as precipitation, temperature, wind, and solar radiation; and by physiographic factors related to geology and topography. As a result, streamflow varies considerably both in time and space. For example, see the variation of daily streamflows in Figure 8 of Riggs and Wolman (this volume). Lins and others (this volume) and Saxton and Shiau (this volume) describe the climatic and physiographic variations throughout the continent.
This chapter describes the variation of runoff (the volume of flow for a given time) in North America and explains the major climatic and physiographic factors underlying this variation. Following a description of common terminology related to runoff, the variation of runoff in various parts of the continent is presented on maps and graphs. The next section describes the effects of climatic, topographic, and geologic factors on runoff using appropriate examples. A final section documents the integrated effects of climate and physiography within a specific watershed as runoff drains from the headwaters to the basin outlet. | <urn:uuid:9a8cbef9-71d2-46c4-8370-25be462fab2b> | 3.46875 | 325 | Academic Writing | Science & Tech. | 24.117987 | 95,596,370 |
- Deep Sea Fauna
- Environmental Variability
- Consequences of DWHOS
- Student Research
- DEEPEND Publications
When the nets come up, it’s time to sort…. Each net is processed one net time so we don’t mix up samples between one net and another. The entire process can take anywhere from four to six hours depending on how full each cod end is. We first identify the organisms and then they go to Nina and Natalie for data entry. Animals are being used for multiple studies once we are back on our labs: DNA barcoding, genetic diversity studies, stable isotope analysis, contaminant analysis and vertical distribution studies.
Here is just a sample of some unique specimens we’ve collected so far!
Photo 1: Nina and Natalie at the data entry station
Photo 2: A sample of the over 600 euphausiids (krill) that team crusty had the pleasure of counting from one net
Photo 3: A selection of bristlemouths and a hatchetfish that was going to processing for the PAH study
Photo 4: Nina with a Fangtooth fish
Photo 5: The mollusca collected on one of the tows- 4 small pelagic snails, one small Vampire squid and a Chiroteuthis mega (deep-sea squid)
One of the new projects onboard this DEEPEND trip is the use of a drone to capture images and video from a different perspective around the Point Sur. Thomas Wheeler is a full time drone operator who contracts with different science and engineering projects that require drone work. This trip, he is assisting Ryan Killackey and Dante Fenolio who are creating a documentary titled “Life in the Dark” which focuses on various organisms that create light.
Why use a drone? Drones are quickly becoming a standard tool that we use in all areas of science. It is very important to capture the true nature of organisms in their habitat and drones can do that with little interference. In addition, using a drone broadens the scanning area for a project so more area can be covered. Lastly, drone footage captures large amounts of data that will be analyzed and used by scientists. The different perspective that drones capture provide the public spectacular images and video of events not often seen by anyone other than the scientists.
Thomas loves that this job allows him to travel to different venues and allows him to contribute to science while doing something he loves. The eternal challenge for drone work of course, is to be able to collect data in a safe manner, in this case, not allow the drone to fall to the bottom of the ocean!
Facts about Thomas’s drone, the Inspire 2 (lovingly named Zephyr):
Battery airtime: 25 minutes
Range: up to 4 miles
Here are pictures that Jon Moore took from the initial deployment and retrieval on Day 1 of this trip, Enjoy!
Photo 1: Inspire 2 ready for launch
Photo 2: Thomas piloting the first mission Photo 3: Ryan collecting the drone on the return
When the MOC10 comes up to the ship, it is time for the whole science team to leap into action. To someone not familiar to the process, it may appear to be utter chaos but each person on the team has a role and things usually run like clockwork. I say “usually” because occasionally, there is a hang-up. One hang-up has been the equipment that runs the MOC last night and today. There has to be communication between the equipment on the net frame to the computer that monitors the entire process for a successful tow. We have a wonderful MOC operator, Gray, who is the master of this equipment and has been out with us for every cruise. He has been working hard to make sure our science can happen! He has spent hours trying to troubleshoot and solve the mystery problem and so far, we have been able to deploy the nets! Thank you, Gray for all of your hard work with this!
Our MOC operator, Gray, prepping the nets
We are waiting for the second trawl of the trip to come up now and we will processing our deep-sea organisms soon! Stay tuned for some animal highlights in the following posts… We collect things from microbes to large fishes and here is a couple of photos from today!
Photo 1: Jon Moore, Tracey Sutton, Tammy Frank sorting a sample Photo 2: Travis Richards catching a Blue Runner
Hi everyone, after checking to make sure all gear, crew, and science team were onboard the R/V Point Sur, we left the dock just after midnight and we have arrived at our first station! Today, the team spent time calibrating the multibeam sonar and putting the nets onto the MOCNESS frame. You will hear more soon from the acoustics team about the sonar and I will describe the MOCNESS for you now.
Well Wishes from the Restore Sargassum Team as we moved gear into the lab
MOCNESS is an acronym for a Multiple Opening and Closing Net and Environmental Sensing System, which will deploy six nets in the water from the surface down to 1500m (~4500 ft). One net at a time opens at a specified depth (1200-1500m, 1000-1200m, 600-1000m, 200-600m, 0-200m), and net 1 which stays open as the whole system goes down to 1500m. At each depth, a net is open for 45 minutes, moving through the water and collects organisms in the cod end (container at end of each net). The whole thing is brought back onto the deck where the science team then processes the collections. We spent a couple of hours today setting up the MOCNESS nets and cod ends in a light rain and we are now ready for our first deployment which is tonight!
Assembling the nets is a team effort
This trawl we are doing tonight is the 100th trawl of the DEEPEND cruises. What an accomplishment! The nets will go down at 9pm and we will be ready to sort through the samples at 3am when processing begins.
Stay tuned for how the 100th trawl goes!
Hello, everyone! The DEEPEND team is preparing and packing up gear for our next DEEPEND cruise which will be July 18th through August 2nd. We are heading out on the R/V Point Sur from Gulfport, MS and are excited to get back out on the big blue! We will have the shiptracker and real-time surface currents maps per usual on the DEEPEND homepage and we will be blogging along the way with our progress and discoveries! Hope you can virtually join us for our adventure, stay tuned! | <urn:uuid:5bd13f17-cf67-4d4a-b86d-5ace053af451> | 3.078125 | 1,397 | News (Org.) | Science & Tech. | 54.188725 | 95,596,374 |
A boson is any particle with a spin that is an integer number (0, 1, 2, ...) of quantum units of angular momentum. Bosons, named by Paul Dirac in 1947 after the Indian physicist Satyendra Nath Bose, are the carrier particles of all fundamental interactions. Bosons do not obey the Pauli exclusion principle. This means there is no limit to the number of bosons that can occupy the same point in space at the same time; so, for example, there is no limit in theory to the brightness of a beam of light. Bosons are one of two main categories of particle in the Standard Model; the other main category is the fermions.
The bosons that serve as carrier particles for the four basic forces in nature – electromagnetism, the strong force, the weak force, and gravity – are known collectively as gauge bosons. This is because their existence is demanded by a principle called gauge invariance.
The photon, the carrier of the electromagnetic force, is a massless, uncharged boson with spin 1. The W and Z bosons, also called intermediate vector bosons, mediate the weak force between leptons and in the decay of hadrons. The Z boson is electrically neutral, whereas the W boson comes in two forms: positively and negatively charged.
The gluon is the carrier particle of the strong interaction that holds quarks together. Gluons are electrically neutral and have spin 1. They are the equivalent in quantum chromodynamics of photons in quantum electrodynamics. Neither quarks nor gluons exist as isolated particles, but only as constituents of hadrons. The as-yet-undetected graviton, presumed to be associated with the gravitational force between masses, is theorised to have spin 2.
The existence of another type of boson, known as the Higgs boson, has been established from observations made at the Large Hadron Collider and the Tevatron beginning in 2012. The Higgs boson was hypothesized as the means by which all other particles in the Standard Model have the masses they do through what is called the Higgs field. The existence of the Higgs, which was first theorised in 1964, completes the Standard Model. | <urn:uuid:b373b76d-2a16-471a-9367-cec485672074> | 3.765625 | 466 | Knowledge Article | Science & Tech. | 45.136439 | 95,596,394 |
August 2, 2017
Say cheese! and get involved with a new citizen science project to learn about the iconic echidna.
Echidna Conservtion Science Initiative, or EchidnaCSI, is a new citizen science project designed to learn more about these spikey monotremes. How many are there? Where do they live? Are they healthy? The answers to these questions will help conservation efforts.
Citizen scientists can get involved in EchidnaCSI by simply using their smart phone and a new app. The app will encourage everyday people to photograph any echidnas they spot in the wild. Once the photo is taken, location information will be sent to researchers, informing them about echidna populations.
Citizen scientists can also get involved by collecting echidna samples. EchidnaCSI is encouraging the bravest of citizens to collect echidna poo. Echidna poo contains valuable DNA and hormones, which can tell researchers about the health and wellbeing of echidnas.
The EchidnaCSI app is now available on the App Store and Google Play. Keep up-to-date by following the EchidnaCSI Facebook page, downloading the flyer, or visit them at Science Alive! from 5-6 August, 2017. | <urn:uuid:b7cb39d0-3b5b-431a-a2b9-6a4979c48d40> | 3.140625 | 264 | News (Org.) | Science & Tech. | 42.819063 | 95,596,450 |
A radiolarian assemblage containing 11 species of both nasellarians and spumellarians was recovered from the Upper Cretaceous Niobrara Formation in southwestern Saskatchewan, Canada. This assemblage represents the first report of Coniacian radiolarians in the entire Western Interior Basin and one of the few reports for the Upper Cretaceous in North America. The presence of radiolarians and the partial disappearance of foraminifera in the only bentonitic interval in this formation suggest that high silica concentrations supplied by volcanic events favored ecological conditions for radiolarians to thrive and or enhanced their preservation before and after deposition. Correlation of this assemblage with other Upper Cretaceous radiolarian assemblages in North America shows a close affinity with the microfauna recovered in the Sverdrup Basin (Canadian Arctic).
Late Cretaceous radiolarians from a bentonite-rich interval at the base of the Niobrara Formation, southwestern Saskatchewan, Canada: biostratigraphic and paleoenvironmental implications
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Juan F. Diaz, Maria I. Velez; Late Cretaceous radiolarians from a bentonite-rich interval at the base of the Niobrara Formation, southwestern Saskatchewan, Canada: biostratigraphic and paleoenvironmental implications. Canadian Journal of Earth Sciences ; 55 (3): 321–329. doi: https://doi.org/10.1139/cjes-2017-0115
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We related macroinvertebrate community structure to physical, chemical, and biological gradients in flow-through constructed wetlands receiving secondarily treated domestic wastewater and lower-nutrient river water in Ohio, USA. Macroinvertebrates collected with benthic colonization plates and emergence traps were analyzed with diversity, biotic, and combination indices and related to seventeen parameters of water quality, substrate characteristics, and primary productivity in both wetland systems. A total of 36 and 39 macroinvertebrate taxa were collected in the wastewater wetland and river wetland, respectively. Invertebrate communities nearest to the wastewater source in the wastewater wetland had significantly lower (mean τ SE) Simpson diversity (0.5 τ 0.13) and Invertebrate Community Index (ICI) scores (2.6 τ 0.8) than those of other sampling locations. Sampling locations near the middle and outflow of the wastewater wetland had diversity scores (0.84 τ 0.01) and ICI scores (4.8 τ 0.7) statistically similar to sites in the river-fed wetlands. Average diel dissolved oxygen and specific conductivity were the best environmental predictors of invertebrate community metrics; these variables along with chemical oxygen demand and nitrate-nitrogen described nearly 90% of the ICI variation in a four-predictor regression model. Multiple correspondence analysis showed sampling locations loosely grouped by average diel dissolved oxygen, which described 65.4% of the overall variation in the gradient data, and specific conductivity, which described and additional 16.4%. Macroinvertebrate analyses are presented as a valuable means of assessing the ecological status of wetlands used to improve water quality and as an important supplement for traditional chemical analyses.
Mendeley saves you time finding and organizing research
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What tell us the finds of carbon and diamonds
in the LDG, other glassy melts and breccias in the Silica-strewnfield
in the Egyptian Great Sand Sea
Upload: April 2018
Diamond is a solid form of carbon
with a cubic crystal structure. Most of them were formed in enormeus
depths in the Earth's mantle. Under high pressure and temperature, carbon-containing
fluids dissolved minerals and replaced them with diamonds. Diamonds are deposited
in igneous rocks known as kimberlites and lamproites
carried to the surface by volcanic eruptions. Extraterrestrial diamonds, mostly
of a microscopic size, are found in carbonaceous chondrites.
In the strewnfield of the Libyan Desert Glass (LDG) is hidden
not only the secret of the creation of this unique glass itself, but also
the origin of some accumulations of carbon/graphite and diamonds /micro-diamonds
embedded in glassy melts within breccias. In the meantime it can be ruled
out that these materials are of extraterrestrial origin. To convincing are
indications for a connection with the widespread volcanism in the region.
Here we have diamonds that have been transported from the earth's mantle to
the earth's surface.
The following locations are known so far, and they should not be the last.
Unfortunately, all the ludicrous interpretations of the elaborate investigations
point in the totally wrong direction, as the citations listed below from the
publications prove. The find of kimberlite (Location
3 and 7) bring the impact theory now the death.
inclusions, polymorphs of graphite and diamond
in a carbonaceous matrix
Breccia 3 (Qaret-el-Hanash)
25°04' / 25°55'
a glassy matrix of kimberlite breccia
Debris in Paleosol
and carbonaceous debris
the Silica area
Dark grey mullite-magnetite-glass
melt rock with numerous diamonds
Zerzura (Kimberlite pipe)
( + micro diamonds)
in Libyan Desert Glass: Effect of microgravity environment
C. Patuelli, R. Serra, S. Coniglione, M. Chiarini
Microgravity and Space Station Utilization, vol. 3, no. 4, 2002
"Samples of Libyan Desert Glass were analyzed by
X-ray micro-diffraction technique. It was identified fourteen nano-sized
crystalline LDG phases with different colours: Coesite, tridymite,
stishovite, baddeleyite, huttonite, yttrium, moissanite, platinium,
polymorphs of diamond and graphite.
The four praphite polymorh phases found in LDG samples can be explained
by taking into account that the graphite came from the earlier history
of the material. The element platinum is extremely scarce in most crustal
rocks. The origin of platinum is from ultra-mafic igneous rocks. Its melting
point is 1775 °C. The zircon oxide mineral Baddeleyite is the product
of the decomposition of zircon at 1775° - 1900°C. Moissanite is a natural
silicon carbide (SiC). Huttonite is a low-temperature and low-pressure
The identification of nine highbaric phases, the
presence of hexagonal diamond with four phases of graphite polymorphs,
as well as huttonite and baddeleyite, confirm that LDG formed by "shock
metamorphism" at very high pressure and temperature. The nano-sized crystalline
phases revealed point out that LDG rapidly solidified.
Preliminary X-ray micro-diffractometry analyses were presented at the
“Silica 96” workshop (Patuelli, 1997). High pressure and high temperature
phases were identified: including samarium, germanium 12T, thorium beta
(this beta phase occurs only at a temperature above 1350°C) and stishovite,
which is a high temperature and pressure form of SiO2."
liquid immiscibility and graphite ribbons in Libyan Desert Glass
G. Pratesi, C. Viti, C. Cipriani, M. Mellini
Geochimica et Cosmochimica Acta, March 2002
"Transmission electron microscopic (TEM) investigation of the dark (brown
or bluish) streaks occurring in Libyan Desert Glass reveals the common
presence of small glass spherules. The spherules, mostly 100 nm
in size, are homogeneously dispersed within the silica-glass matrix. The
complete absence of electron
diffraction effects confirms their amorphous nature. The spherules are
Al-, Fe- and Mg-enriched with respect to the surrounding silica matrix
and their (Mg+Al+Fe) : Si ratio is close to 1. The silica-glass matrix
and amorphous spherules form an emulsion texture (i.e., globules of one
glass in a matrix of another glass), which originates from silicate-silicate
The silica glass also contains carbonaceous inclusions
consisting of 5–50 nm thick, polygonalized graphite
ribbons that form closed structures up to 200 nm in diameter.
Rare carbon-bearing inclusions randomly occur within the silica-glass
matrix. Their presence is ubiquitous and not limited to the regions with
dark streaks. C-bearing inclusions produce an evident C peak in the EDS
spectra. The inclusions consist of ring-shaped polygonalized ribbons,
5–50 nm thick, typically forming closed structures with an overall diameter
of ~200 nm. Their SAED patterns consist of rings with d-spacings of 3.35,
2.09 and 1.67 A: these values correspond to graphite (3.36, 2.13-2.03,
1.678 A, JCPDS 23-64). Lattice imaging shows 3.35 A polygonized (002)
lattice fringes. The fringes are quite regular, thus indicating good structural
order with no evidence of deformation or defects. Dark vertical bands
are evident at the polygonal edges and are interpreted as Moire textures."
Probably debris of
First paper by Aly Barakat, the discoverer of the stone
5.3-THE MINERALOGICAL COMPOSITION:
The mineralogical composition includes; diamond,
graphite, goethite, quartz calcite and halite.
5.3.1-Diamond: Diamond aggregations occur as tiny angular grains (fragments)
showing the characteristic lustre and cleavage. Some of these grains show
indications of octahedral form), but others are suggestive of partial hexagonal
form. EDAX analysis (Fig. 5.3) of some grains indicates that they consist
essentially of C (~98 %).
The XRD analysis data are consistent with the presence of diamond of interplanar
distances (d) 2.07, 1.259, and 1.881 (JCPDS, card 6-675) as indicated by the
Camera method. Moreover, diamond appears through the chart of the other X-ray
Raman spectrometric analysis of the bright aggregates confirms the presence
of diamond in a polycrystalline status, as witnessed by the significantly
broad peak at 1331 cm-1, spectra b and d). In spectrum (b), diamond is associated
with graphite (peak in the 1580 cm-1 region). In spectrum (d), the broad band
at 1332 cm-1 is a good evidence for the presence of diamond in the form of
microcrystalline aggregates (note the sharp peak of the well crystalline diamond
on the reference spectrum c). Thus, the observed large grains represent quite
large aggregates of micrometer-sized crystallites.
5.3.2-Graphite: Graphite occurs as thin laminated encrustation coating and
embedding the diamond aggregations. The Raman spectroscopy confirms also the
intimate association between graphite and diamond (Fig. 5.5, spectrum b).
Graphite is also present in the form of microcrystalline grains. In figure
(5.5, spectrum a) the single peak at 1580 cm-1 is of crystalline graphite
(mean basal plane >>1000 Ĺ). This phase is also known as the G mode. Progressive
disorder in graphite is reflected in the Raman spectrum by the broadening
and shifting of this band to higher wave numbers, and by development of an
additional band near 1360 cm-1 (also known as the D mode) (Pasteris and Wopenka,
1991; Hirlimann, et al., 1992). The peak around 1360 cm-1 in spectrum b (Fig.
5.5) is aconvolution of two peaks. This is due to the presence of both diamond
and graphite in intimate association.
Probably the first detected
Kimberlite pipe nearby the Silica strewnfield
The most important indication for the emergence
of Qaret-el-Hanash, which I postulate now as a eroded kimberlite pipe, are
the photos of Ursula Steiner (Switzerland), which come from the top and outside
slope of the structure. They document clear the subvolcanic origin of Qaret-el-Hanash
impressively. Some photos show a strange, material of a dark (carbonaceous
?) melt with included many diverse fragments, among ferruginous sandstone,
basement debris, glass and yellow jasper. The melt contain also visibly large
dark brown diamonds.
This piece from the
breccia contain large dark brown diamonds
a trekking-tour in 2012
DISCOVERY OF Fe-Cr-Ni SPECKS WITHIN QARET EL-HANASH
BRECCIA OF THE LIBYAN GLASS AREA SOUTH WESTERN EGYPT
A. El-Kammar, I. Arafa, K. A. Soliman & A. Barakat --7th International
Conference on the Geology of the Arab World, Cairo University, Feb. 2004,
"The rock consists of various fragments of local sandstone,
i.e., from the area of the glass distribution itself. Fragments of igneous
source have never been recorded. The rock fragments range from fraction
of mm up to 4-cm in diameter, in the collected specimens. The rock fragments
vary in colour from creamy white to brownish-red. They are angular to
subrounded and embedded in a dull greyish-black matrix. The microscopic
investigation and scanning electron microanalysis confirmed the above-mentioned
observation and showed that the matrix consists of shattered and fragmented
quartz grains of various sizes. In addition to quartz, the matrix contains
many other phases, such as glass, zircon, clay minerals, wollastonite,
ilmenite, Mg-ilmenite, rutile and Fe-Cr-Ni specks.
There are several metallic specks of various sizes ranging from 1 micron
up to about 10 micron, dispersed in the matrix of Qaret el Hanash breccia.
They invade some of the quartz grains. These specks are mainly of irregular
outlines and some of them show clear fissures. They are associated with
glass and intercalated in some cases with halite. EDAX analyses of such
specks indicate that they consist of native Fe, Cr and Ni, in addition
to subordinate Si and Ca. Finer particles of similar appearance have also
been noticed by the petrographical microscope through the fractures of
some of the quartz grains.
The most interesting achievement of the chemical analyses is the detection
of high Ir content (2.0-2.2 ppb) within the breccias. This value represents
the highest reported values for the area. The reported value of Ir in
other breccias in the area is around 1.6-1.9 ppb. The highest reported
concentration of Ir by the previous studies was detected from the black
streak portions from the Libyan glass itself is 1.25 ppb."
Aly Barakat on May 19, 2018: The samples contains tiny particles
of Fe-Cr-Ni, and other phases includes tiny grains of
moissanite and diamond.
Aly Barakat, 2004: At latitude
25°22′51″ N and longitude 25°27′34″ E is present site of a megascopic
breccia. The petrographical and mineralogical studies carried out on the
breccia indicate that it represents impact breccia. In addition
to the brecciation of the quartz grains some of these grains show PFs
and PDFs. The zircon of this breccia shows evidence of deformation as
represented by the fragmented nature of some the studied grains and by
non-stoichiometric contents of ZrO2 and SiO2. The detection of
glass and graphite is accounted also
for the impact origin of this breccia.
5. Debris in Paleosol
Polymetallic and carbonaceous debris in paleosol from the
Libyan Desert Glass strewn field, SW Egypt: Evidence of a cometary impact.
M. A. G. Andreoli, & M. Di Martino et al. -- Lunar and Planetary
Science XLVIII (2017),
An expedition in November 2011 to the find area of "Hypatia"
failed to recover additional hand specimens of "Hypatia" material, but
samples of pedogenic pebbly deposits. One of these samples (WZER-8) was
collected 3.5 km south of the Hypatia sampling site in the dune (25°18.11'
After fractional separations of the sample was identified evidence of
hard amorphous carbon and submicron diamonds
as well as unusual metallic mineral grains, all those found in the "Hypatia"
The unusual metallic grains and carbonaceous particles tentatively grouped
into 4 types:
Type I grains and spherules range from 10-20 μm up to 130 μm. SEM-EDX
data indicate that the smaller spherules are metallic with a wide compositional
range comprising Ti, Ag, Al, and Si in varying porportions, and Ca, O,
Na, Mg and S as variable, minor constituents. The largest spherules are
pale green and vitreous and consist entirely of P, Si with no detectable
Type II grains are much larger (length: 60 μm to 1.2 mm) and consist
a) sintered aggregates of Pb metal particles
b) strongly sintered clusters of α-Ti (+1.0 at.% Al) subgrains
c) more brittle aggregates of seemingly submicron, Sn-Ca alloy particles.
The Ti metal grains in places host clusters of quenched gas bubbles, blobs
of Ti aluminide, veinlets of non-stoichiometric Ti nitride, Al oxycarbonitride,
and particles of Zr, Ag, and Zn. A distinctive feature of the Type II
grains is their localized coating by (C, O bearing) carbonaceous films
and filaments up to 300 μm in length. Although these resemble fungal hyphae
and tendrils in SEM images, Raman spectra prove that they comprise partly
Type III grains are shard-like in shape and occur either as partly
oxidized branching (70 μm x 50 μm) Al particles decorated by μm-size Bi
granules, or as lace-textured Ti particles partly enveloped by Type II
grains. Petrographic textural analysis of multiple 3-D sections of the
shard indicate that the Type II (and perhaps Type I) grains were derived
from the partial to complete melting of the Type III shards.
grains are morphologically and compositionally diverse, with common characteristics
being Carbon as the major constituent. Moissanite (SiC) grains were the
first to be positively identified from petrography and Raman spectra.
Other grains display a range of textures, including one resembling a honeycomb
with N as second major constituent and minor, varying amounts of S and
Cl. The Raman spectra of these N-rich grains show faint, indistinct D
and G bands but distinctive peaks in the 3000 cm-1 region, indicative
of C:H bonds.
6. Mullite-magnetite-glass melt rock
About the Occurrence of micron-sized diamonds in the mullite-magnetite-silica
glass boulders in the Gilf Kebir area of western Egypt
M.A.G. Andreoli -- School of Geosciences, University
of the Witwatersrand, South Africa; Unpublished document (2017)
|"Dark grey mullite-magnetite-glass melt
rock (left); numerous diamonds were
found in the polished, light sandy grey slab (bottom left) but found absent
in the core of the dark, glassy patch." The location is in the Silica
area, southern of "Hypatia" stone.
|"From available evidence (Raman spectrum)
diamonds and disordered graphite are likely to be found in the majority
of the dark patches present in the photomicrographs"
Probably a second detected
|Cigolini & Di Martino --
Here a spectacular find of a breccia from a crater-like structure
is presented, in which probably a swarm
of micro-diamonds can be seen.
Unfortunately, apart from the identified location of the find by me
(25°16'46 "/ 25°10'05") there are no
further comments. The crater is to find in the central wadi of the
Zerzura Plateau, which is located west of the Silica strewnfield.
The crater is nearly round and in no case a depression caused by water
erosion. In the crater's center there is at least one round hole with
a plug of the breccias.
The breccia in the crater may be a kimberlitic emplacement in the
decomposition phase. The diamonds (white "sugar") are difficult to
recognize in the photos.
But some forms seem to be transparent crystals.
Romano Serra, University of Bologna, has sent me some
new revealing photos from the crater and the breccia. It were only made
30 thin sections to find PDF's. | <urn:uuid:84a1b1f0-1326-4734-942d-dcac2758f735> | 3.28125 | 4,050 | Content Listing | Science & Tech. | 48.103596 | 95,596,551 |
In quantum mechanics and quantum field theory, the propagator is a function that specifies the probability amplitude for a particle to travel from one place to another in a given time, or to travel with a certain energy and momentum. In Feynman diagrams, which serve to calculate the rate of collisions in quantum field theory, virtual particles contribute their propagator to the rate of the scattering event described by the respective diagram. These may also be viewed as the inverse of the wave operator appropriate to the particle, and are, therefore, often called (causal) Green's functions (called "causal" to distinguish it from the elliptic Laplacian Green's function).
In non-relativistic quantum mechanics, the propagator gives the probability amplitude for a particle to travel from one spatial point at one time to another spatial point at a later time. It is the Green's function (fundamental solution) for the Schrödinger equation. This means that, if a system has Hamiltonian H, then the appropriate propagator is a function
where Hx denotes the Hamiltonian written in terms of the x coordinates, δ(x) denotes the Dirac delta-function, Θ(t) is the Heaviside step function and K(x, t ;x′, t′) is the kernel of the differential operator in question, often referred to as the propagator instead of G in this context, and henceforth in this article. This propagator can also be written as
where Û(t, t′) is the unitary time-evolution operator for the system taking states at time t′ to states at time t.
The quantum mechanical propagator may also be found by using a path integral,
where the boundary conditions of the path integral include q(t) = x, q(t′) = x′. Here L denotes the Lagrangian of the system. The paths that are summed over move only forwards in time, and are integrated with the differential which follows the path in time.
In non-relativistic quantum mechanics, the propagator lets you find the wave function of a system given an initial wave function and a time interval. The new wave function is given by the equation
Basic examples: propagator of free particle and harmonic oscillatorEdit
For a time-translationally invariant system, the propagator only depends on the time difference t − t′, so it may be rewritten as
The latter may be obtained from the previous free particle result upon making use of van Kortryk's SU(2) Lie-group identity,
valid for operators and satisfying the Heisenberg relation .
For the N-dimensional case, the propagator can be simply obtained by the product
In quantum field theory, the theory of a free (non-interacting) scalar field is a useful and simple example which serves to illustrate the concepts needed for more complicated theories. It describes spin zero particles. There are a number of possible propagators for free scalar field theory. We now describe the most common ones.
- x, y are two points in Minkowski spacetime.
- is the d'Alembertian operator acting on the x coordinates.
- δ(x − y) is the Dirac delta-function.
with ε implying the limit to zero. Below, we discuss the right choice of the sign arising from causality requirements.
The solution is
is the 4-vector inner product.
The different choices for how to deform the integration contour in the above expression lead to various forms for the propagator. The choice of contour is usually phrased in terms of the integral.
The integrand then has two poles at
so different choices of how to avoid these lead to different propagators.
A contour going clockwise over both poles gives the causal retarded propagator. This is zero if x-y is spacelike or if x ⁰< y ⁰ (i.e. if y is to the future of x).
This choice of contour is equivalent to calculating the limit,
is the Heaviside step function and
is the commutator.
A contour going anti-clockwise under both poles gives the causal advanced propagator. This is zero if x-y is spacelike or if x ⁰> y ⁰ (i.e. if y is to the past of x).
This choice of contour is equivalent to calculating the limit
A contour going under the left pole and over the right pole gives the Feynman propagator.
This choice of contour is equivalent to calculating the limit
This expression can be derived directly from the field theory as the vacuum expectation value of the time-ordered product of the free scalar field, that is, the product always taken such that the time ordering of the spacetime points is the same,
The usual derivation is to insert a complete set of single-particle momentum states between the fields with Lorentz covariant normalization, and to then show that the Θ functions providing the causal time ordering may be obtained by a contour integral along the energy axis, if the integrand is as above (hence the infinitesimal imaginary part), to move the pole off the real line.
The propagator may also be derived using the path integral formulation of quantum theory.
Momentum space propagatorEdit
They are often written with an explicit ε term although this is understood to be a reminder about which integration contour is appropriate (see above). This ε term is included to incorporate boundary conditions and causality (see below).
For a 4-momentum p the causal and Feynman propagators in momentum space are:
For purposes of Feynman diagram calculations, it is usually convenient to write these with an additional overall factor of −i (conventions vary).
Faster than light?Edit
The Feynman propagator has some properties that seem baffling at first. In particular, unlike the commutator, the propagator is nonzero outside of the light cone, though it falls off rapidly for spacelike intervals. Interpreted as an amplitude for particle motion, this translates to the virtual particle travelling faster than light. It is not immediately obvious how this can be reconciled with causality: can we use faster-than-light virtual particles to send faster-than-light messages?
The answer is no: while in classical mechanics the intervals along which particles and causal effects can travel are the same, this is no longer true in quantum field theory, where it is commutators that determine which operators can affect one another.
So what does the spacelike part of the propagator represent? In QFT the vacuum is an active participant, and particle numbers and field values are related by an uncertainty principle; field values are uncertain even for particle number zero. There is a nonzero probability amplitude to find a significant fluctuation in the vacuum value of the field Φ(x) if one measures it locally (or, to be more precise, if one measures an operator obtained by averaging the field over a small region). Furthermore, the dynamics of the fields tend to favor spatially correlated fluctuations to some extent. The nonzero time-ordered product for spacelike-separated fields then just measures the amplitude for a nonlocal correlation in these vacuum fluctuations, analogous to an EPR correlation. Indeed, the propagator is often called a two-point correlation function for the free field.
Since, by the postulates of quantum field theory, all observable operators commute with each other at spacelike separation, messages can no more be sent through these correlations than they can through any other EPR correlations; the correlations are in random variables.
Regarding virtual particles, the propagator at spacelike separation can be thought of as a means of calculating the amplitude for creating a virtual particle-antiparticle pair that eventually disappears into the vacuum, or for detecting a virtual pair emerging from the vacuum. In Feynman's language, such creation and annihilation processes are equivalent to a virtual particle wandering backward and forward through time, which can take it outside of the light cone. However, no signaling back in time is allowed.
Explanation using limitsEdit
This can be made clearer by writing the propagator in the following form for a massless photon,
This is the usual definition but normalised by a factor of . Then the rule is that one only takes the limit at the end of a calculation.
One sees that
Hence this means a single photon will always stay on the light cone. It is also shown that the total probability for a photon at any time must be normalised by the reciprocal of the following factor:
We see that the parts outside the light cone usually are zero in the limit and only are important in Feynman diagrams.
Propagators in Feynman diagramsEdit
The most common use of the propagator is in calculating probability amplitudes for particle interactions using Feynman diagrams. These calculations are usually carried out in momentum space. In general, the amplitude gets a factor of the propagator for every internal line, that is, every line that does not represent an incoming or outgoing particle in the initial or final state. It will also get a factor proportional to, and similar in form to, an interaction term in the theory's Lagrangian for every internal vertex where lines meet. These prescriptions are known as Feynman rules.
Internal lines correspond to virtual particles. Since the propagator does not vanish for combinations of energy and momentum disallowed by the classical equations of motion, we say that the virtual particles are allowed to be off shell. In fact, since the propagator is obtained by inverting the wave equation, in general, it will have singularities on the shell.
The energy carried by the particle in the propagator can even be negative. This can be interpreted simply as the case in which, instead of a particle going one way, its antiparticle is going the other way, and therefore carrying an opposing flow of positive energy. The propagator encompasses both possibilities. It does mean that one has to be careful about minus signs for the case of fermions, whose propagators are not even functions in the energy and momentum (see below).
Virtual particles conserve energy and momentum. However, since they can be off the shell, wherever the diagram contains a closed loop, the energies and momenta of the virtual particles participating in the loop will be partly unconstrained, since a change in a quantity for one particle in the loop can be balanced by an equal and opposite change in another. Therefore, every loop in a Feynman diagram requires an integral over a continuum of possible energies and momenta. In general, these integrals of products of propagators can diverge, a situation that must be handled by the process of renormalization.
If the particle possesses spin then its propagator is in general somewhat more complicated, as it will involve the particle's spin or polarization indices. The differential equation satisfied by the propagator for a spin 1⁄2 particle is given by
where I4 is the unit matrix in four dimensions, and employing the Feynman slash notation. This is the Dirac equation for a delta function source in spacetime. Using the momentum representation,
the equation becomes
where on the right-hand side an integral representation of the four-dimensional delta function is used. Thus
By multiplying from the left with
(dropping unit matrices from the notation) and using properties of the gamma matrices,
The iε downstairs is a prescription for how to handle the poles in the complex p0-plane. It automatically yields the Feynman contour of integration by shifting the poles appropriately. It is sometimes written
for short. It should be remembered that this expression is just shorthand notation for (γμpμ − m)−1. "One over matrix" is otherwise nonsensical. In position space one has
This is related to the Feynman propagator by
The propagator for a massive vector field can be derived from the Stueckelberg Lagrangian. The general form with gauge parameter λ reads
With this general form one obtains the propagator in unitary gauge for λ = 0, the propagator in Feynman or 't Hooft gauge for λ = 1 and in Landau or Lorenz gauge for λ = ∞. There are also other notations where the gauge parameter is the inverse of λ. The name of the propagator, however, refers to its final form and not necessarily to the value of the gauge parameter.
Feynman ('t Hooft) gauge:
Landau (Lorenz) gauge:
Related singular functionsEdit
The scalar propagators are Green's functions for the Klein–Gordon equation. There are related singular functions which are important in quantum field theory. We follow the notation in Bjorken and Drell. See also Bogolyubov and Shirkov (Appendix A). These functions are most simply defined in terms of the vacuum expectation value of products of field operators.
Solutions to the Klein–Gordon equationEdit
The commutator of two scalar field operators defines the Pauli–Jordan function by
and is zero if .
Positive and negative frequency parts (cut propagators)Edit
We can define the positive and negative frequency parts of , sometimes called cut propagators, in a relativistically invariant way.
This allows us to define the positive frequency part:
and the negative frequency part:
The anti-commutator of two scalar field operators defines function by
Green's functions for the Klein–Gordon equationEdit
The retarded, advanced and Feynman propagators defined above are all Green's functions for the Klein–Gordon equation.
They are related to the singular functions by
- The mathematics of PDEs and the wave equation, p 32., Michael P. Lamoureux, University of Calgary, Seismic Imaging Summer School, August 7–11, 2006, Calgary.
- Ch.: 9 Green’s functions, p 6., J Peacock, FOURIER ANALYSIS LECTURE COURSE: LECTURE 15.
- E. U. Condon, "Immersion of the Fourier transform in a continuous group of functional transformations", Proc. Natl. Acad. Sci. USA 23, (1937) 158–164. online
- Wolfgang Pauli, Wave Mechanics: Volume 5 of Pauli Lectures on Physics (Dover Books on Physics, 2000) ISBN 0486414620 , cf. Section 44.
- Huang, p. 30
- Greiner & Reinhardt 2008, Ch.2
- "Graviton and gauge boson propagators in AdSd+1" (PDF).
- Bjorken and Drell, Appendix C
- Bjorken, J.; Drell, S. (1965). Relativistic Quantum Fields. New York: McGraw-Hill. ISBN 0-07-005494-0. (Appendix C.)
- Bogoliubov, N.; Shirkov, D. V. Introduction to the theory of quantized fields. Wiley-Interscience. ISBN 0-470-08613-0. (Especially pp. 136–156 and Appendix A)
- DeWitt-Morette, C.; DeWitt, B. (eds.). Relativity, Groups and Topology. Glasgow: Blackie and Son. ISBN 0-444-86858-5. (section Dynamical Theory of Groups & Fields, Especially pp. 615–624)
- Greiner, W.; Reinhardt, J. (2008). Quantum Electrodynamics (4th ed.). Springer Verlag. ISBN 9783540875604.
- Greiner, W.; Reinhardt, J. (1996). Field Quantization. Springer Verlag. ISBN 9783540591795.
- Griffiths, D. J. (1987). Introduction to Elementary Particles. New York: John Wiley & Sons. ISBN 0-471-60386-4.
- Griffiths, D. J. (2004). Introduction to Quantum Mechanics. Upper Saddle River: Prentice Hall. ISBN 0-131-11892-7.
- Halliwell, J.J.; Orwitz, M., Sum-over-histories origin of the composition laws of relativistic quantum mechanics and quantum cosmology, arXiv: , Bibcode:1993PhRvD..48..748H, doi:10.1103/PhysRevD.48.748
- Huang, Kerson (1998). Quantum Field Theory: From Operators to Path Integrals. New York: John Wiley & Sons. ISBN 0-471-14120-8.
- Itzykson, C.; Zuber, J-B. (1980). Quantum Field Theory. New York: McGraw-Hill. ISBN 0-07-032071-3.
- Pokorski, S. (1987). Gauge Field Theories. Cambridge: Cambridge University Press. ISBN 0-521-36846-4. (Has useful appendices of Feynman diagram rules, including propagators, in the back.)
- Schulman, L. S. (1981). Techniques & Applications of Path Integration. New York: John Wiley & Sons. ISBN 0-471-76450-7. | <urn:uuid:87a124b5-e7e3-4b14-b5f1-bd12e4e67751> | 3.3125 | 3,641 | Knowledge Article | Science & Tech. | 47.360791 | 95,596,580 |
PARIS – (AFP) – Earth was cooling until the end of the 19th century and a hundred years later, the planet’s surface was on average warmer than at any time in the previous 1,400 years, according to climate records presented on Sunday.
In a study spanning two millennia published in Nature Geoscience, scientists said a “long-term cooling trend” around the world swung into reverse in the late 19th century.
In the 20th century, the average global temperature was 0.4 degrees Celsius (0.7 degrees Fahrenheit) higher than that of the previous 500 years, with only Antarctica bucking the trend.
From 1971-2000, the planet was warmer than at any other time in nearly 1,400 years.
This measure is a global average, and some regions did experience warmer periods than that — but only for a time. Europe, for instance, was probably warmer in the first century AD than at the end of the 20th century.
The investigation is the first attempt to reconstruct temperatures over the last 2,000 years for individual continents.
It seeks to shed light on a fiercely-contested aspect in the global-warming debate.
Sceptics have claimed bouts of cooling or warming before the Industrial Revolution — including two episodes in Europe called the Medieval Warm Period and the Little Ice Age — are proof that climate variations are natural, not man-made.
The new study does not wade into the debate about greenhouse gases, but points to two planetary trends.
The first is a clear, prolonged period of cooling. It may have been caused by a combination of factors, including an increase in volcanic activity, with stratospheric ashes reflecting the sunlight, or a decrease in solar activity or tiny changes in Earth’s orbit, both of which would diminish sunlight falling on the planet.
The cooling — between 0.1-0.3 C (0.2-0.6 F) per thousand years, depending on the region — went into reverse towards the end of the 19th century, and was followed by an intensifying period of warming in the 20th, the paper said.
Beneath this global trend over 2,000 years were episodes of continental cooling or warming, some of which were quite long.
And some continents lagged the overall planetary trend, but with the exception of Antarctica, all followed it.
“Distinctive periods, such as the Medieval Warm Period or the Little Ice Age stand out, but do not show a globally uniform pattern on multi-decadal time scales,” said Heinz Wanner of the University of Bern in Switzerland, one of 78 researchers from 24 countries who took part in the project.
“There are things that are common to all the regions of the planet — long-term cooling, until the 19th century, followed by warming on all continents, except for Antarctica, where it is less clear, but also strong variations from one region to another,” Hugues Goosse, a climatologist at Belgium’s Catholic University of Leuven, told AFP.
Previous research into climate change has pointed to a warming spurt in the 20th century and attributed it to the rise of heat-trapping carbon gases emitted by burning coal, oil and gas.
The warming trend shifted up a gear in the middle of the 1970s, in line with record-breaking levels of carbon dioxide (CO2), according to this past research.
2012 saw the 36th straight year that global temperatures were above average since 1880, when scientifically acceptable records were first kept, and was the ninth or 10th warmest on record, US scientists said in January.
The temperature reconstruction published on Sunday was coordinated by a scientific initiative called the Past Global Changes (PAGES) 2K Network.
It brings together weather data as well as telltales of temperature variation from tree rings, pollen, corals, lake and marine sediments, ice cores and stalagmites garnered at 511 locations across seven continental-scale regions.
Climate records for Africa, though, were sparse, the researchers cautioned. | <urn:uuid:2755c630-72e5-480f-ba3d-4e7f0363458d> | 3.578125 | 847 | News Article | Science & Tech. | 44.90151 | 95,596,585 |
But robot space crafts are sent very much farther.
These have visited the distant planets.
These robot space crafts are called space probes.
What is a Space Probe?Space probes carry cameras and many kinds of instruments to study the planets they visit. They send information back to earth by radio.
Probes must be launched from the earth at a very great speed—more than 24,800 miles (40,000 kilometers) an hour.
Then they can escape from the earth's gravity.
Aiming the probe is very difficult, because the planet it must reach is always moving. The probe must be aimed so that it reaches a point in space almost at the same time as its target. It must do this after a journey of many millions of miles, lasting for years.
Voyager space probesIt is an astonishing fact that most probes sent to the planets have reached their targets. In 1989, the American probe Voyager 2 flew past the planet Neptune almost exactly on time, after a 12-year journey. The planet was nearly 3.1 billion miles (5 billion kilometers) away from earth at the time. From this distance, the radio waves from Voyager took over four hours to reach the earth.
A Voyager probe photographed Saturn on its journey into the outer solar system. It used nuclear generators to make electricity.
Solar cells couldn’t be used because sunlight is too weak near Saturn.
Venera space probeMost probes study a planet as they fly past it. But some actually land on the planet and report back from its surface.
A Russian probe, called Venera, was the first to land on a planet. It parachuted down to Venus in 1970. Since then, several Venera probes have sent back pictures of its surface.
Two American Viking probes landed on Mars in 1976. They sent back pictures and reported on the Martian weather. They also examined the soil for signs of life—but didn't find any! | <urn:uuid:e4d3a886-ef22-43e4-a86f-2f375b5474c0> | 4.125 | 399 | Knowledge Article | Science & Tech. | 63.735727 | 95,596,607 |
The carnivorous Venus flytrap carefully plans its meals: It can count how often it is touched by an insect to calculate the digestive effort. This discovery has been made by plant scientists of the University of Würzburg.
Usually, plants are eaten by animals and humans. With carnivorous plants, however, it's the other way round: They have specialised in animals as an extra source of nutrition to help them survive in moors or other nutrient-poor sites.
Take the Venus flytrap (Dionaea muscipula) for example: It has a trapping structure formed by the terminal portion of leaves and is triggered by tiny hairs on their inner surface. These sensors allow the plant to discover, catch and digest flies and other fast animals.
The trap's insides are covered by a turf of red glands. This flower-like appearance combined with fruity smells attracts many insects. Looking for nectar, the visitors inevitably touch the three sensor hairs located on each of the lobes. Based on the number of times the trigger hair is stimulated, the plant decides whether to snap the trap closed and start digestion. This means that the plant is capable of counting.
The discovery was made by an international team of researchers around biophysicist Professor Rainer Hedrich from the University of Würzburg. Their work has been published in the renowned journal Current Biology.
Trap closes on "two"
If a trigger hair on the Venus flytrap is stimulated only slightly, it will signal the first prey contact by transmitting a bio-electrical signal. "One signal does not yet cause a reaction – it could be false alarm after all," says Hedrich. But a second stimulation already causes the trap to snap close in the blink of an eye.
If the prey stayed calm now, there would be no other signal. In that case, the trap will open again after a half day. But since the trapped animals usually put up quite a fight, they trigger a virtual fireworks of signals sealing their fate for good.
This is because the Venus flytrap can count further, as Hedrich's colleague Sönke Scherzer found out. He measured that a trapped insect triggers some 60 signals per hour. To imitate the contact stimuli, Scherzer nudged individual sensory hairs up to 60 times in an hour to see what happened.
Digestive juices start to flow from "five"
The result: Two or more stimuli activate the pathway of the contact and wound hormone jasmonate JA. At five and more signals, the plant additionally activates the genes for digestions enzymes in all of its 37,000 glands. This activation does not take place if the jasmonate signal pathway is suppressed in experiments prior to mechanical stimulation. "We have thus proved that the electrical signal is converted into a hormone signal in the glands," Hedrich further.
Five or more signals also stimulate the transport molecules that provide for the absorption of the digested insects into the plant. While searching for this mechanism, one gene caught the attention of Würzburg Ph.D. student Jennifer Böhm. It is activated by both touching the sensory hairs and by the hormone jasmonate. She was able to demonstrate that it is an ion channel which transports sodium. Large quantities of this nutrient salt accrue when the insects are digested.
The plant can also do maths
"We asked ourselves whether the trap can calculate how many channels it must provide to remove the sodium," Hedrich explains. Obviously, the plant is able to do that: The bigger the prey animal, the more fiercely it will struggle and the more frequently the sensory hairs are stimulated. In that case, the Venus flytrap will produce more ion channels than for a weakly struggling animal.
And what about the plant's memory? According to Hedrich, the Venus flytrap can remember the number of prey contacts for at least four hours. Now the researchers want to study the molecular bases of retentivity and learn whether the sensory performance of plants and animals share similar underlying principles.
Funded by the European Research Council
Hedrich's exploration of the Venus flytrap and other carnivorous plants is backed by top-level funding: In 2010, the European Research Council (ERC) allocated him an "Advanced Grant" worth 2.5 million euros for this purpose. Within the scope of the ERC project "Carnivorom", Hedrich's team is on the lookout for those genes that make plants carnivorous.
„The Venus flytrap Dionaea muscipula counts prey-induced action potentials to induce sodium uptake“, Böhm, J., Scherzer, S., Krol, E., Kreuzer, I., von Meyer, K., Lorey, C., Mueller, T.D., Shabala, L., Monte, I., Solano, R., Al-Rasheid, K.A.S., Rennenberg, H., Shabala, S., Neher, E., Hedrich, R., Current Biology, January 21, 2015, DOI 10.1016/j.cub.2015.11.057
Prof. Dr. Rainer Hedrich, Department of Botany I of the University of Würzburg, Phone: +49 931 31-86100, email@example.com
Robert Emmerich | Julius-Maximilians-Universität Würzburg
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Waterproof Sand Could Green A Desert Planet
Waterproof sand, also called hydrophobic sand could increase food production as well as put off the coming water wars.
(Waterproof (or hydrophobic) sand)
By simply laying down a 10-centimetre blanket of DIME Hydrophobic Materials sand beneath typical desert topsoils, the new super sand stops water below the roots level of the plants and maintains a water table, giving greenery a constant water supply...
“It’s super thin,” Schulze said. “Every single sand kernel gets a skin, a coating, which encloses it.”
The nanotechnology coating is so thin, in fact, that it can’t be seen by the naked eye and measures 12,500 to 13,500 micro millimetres.
To date, it’s been approved by the Federal Environment Agency (FEA) in Germany which, according to German scientist Helmut Schulze, has issued a no-objection certificate for the product declaring it as ecologically safe.
The sand has been undergoing tests for more than a year; with date palms and grasses, researchers see a 25% increase in the root systems when using hydrophobic sand. Traditional watering of desert plants occurs five or six times per day; use of waterproof sand could reduce this to just one watering, according to researchers. The sand also prevents underground desert salinity from leaching upward.
Frank Herbert also had some thoughts about greening the desert; he wrote about chromoplastic dew collectors that could pull moisture from the air for small plants.
However, I'm thinking that if you wanted to go to the effort of coating each grain of sand in Dubai with SP-0HFS 1609, you might as well give every grain a 'brain' of nanotransistors as well. Then, we could construct a gigagnostotron like the one described in Stanislaw Lem's 1965 novel The Cyberiad: Fables for the Cybernetic Age.
The desert on our planet is in reality no desert, but a Gigagnostotron, in other words a good 10^9 times more powerful than this primitive device of yours. Our ancestors... thought to make the very sand beneath their feet intelligent..."
(Read more about Lem's gigagnostotron)
From Next Big Future.
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Small freshwater biofoulers carry a big price tag
Anyone that has spent time at a seaside pier has witnessed the destruction barnacles wreak on boat hulls. But biofouling animals are not limited to marine environments. A new paper published in the journal Frontiers in Ecology and the Environment estimates that the global management of freshwater mussels, clams, and other clinging animals costs $277 million U.S. dollars annually.
Biofoulers are organisms that accumulate underwater on hard surfaces, to the detriment of property and economically important activities, such as shipping, power generation, and water treatment. While plants and algae can act as freshwater biofoulers, the study focused on the impact of animals. Eleven groups known to cause problems were investigated, among them mussels, clams, snails, crustaceans, sponges, and insects.
David Strayer is a freshwater ecologist at the Cary Institute of Ecosystem Studies and one of the paper's authors. "A lot of attention has been given to marine biofouling because it costs a ton of money. Less is known about freshwater impacts. We found most of the economic burden is currently shouldered by utilities. Hydroelectric power plant cooling systems and water treatment intake pipes are particularly vulnerable to damages."
Many freshwater biofoulers are filter-feeders. These animals readily colonize pipes and channel walls, where they collect food from the passing water. Coverage can be extensive. When water treatment intake pipes and filters clog, water flow is obstructed, hastening the corrosion of costly infrastructure. Infestation in hydroelectric power station channels decreases the efficiency of water flow used for power generation.
Management has involved keeping biofoulers out, keeping their numbers low, and killing off infestations. Specialized filters can stop animals from entering facilities that rely on untreated water. To prevent accumulation on hard surfaces, copper alloys, anti-fouling coatings, and ultraviolet light are among the methods used. At water treatment plants and power stations repelling chemicals like chlorine and mechanical cleaning are the most common controls.
Strayer notes, "There are a cornucopia of strategies to combat biofoulers, but most are either costly, or come with the price of polluting water and poisoning non-target organisms."
Given our increasing demand for water and electricity, without action the problem is likely to intensify. First author Daisuke Nakano of Japan's Central Research Institute of Electric Power writes, "Impacts of freshwater biofoulers may soon increase as humans inadvertently move these species around the world, as global demand for freshwater rises, and as human activities favor biofouling species by providing them with suitable habitat."
New water treatment plants and power stations will be susceptible to biofouling. And nutrient pollution and climate change may favor biofoulers. Filter-feeding biofoulers – among the most costly – thrive in the nutrient-rich waters common in developed areas, where they establish on engineered surfaces like concrete walls. Climate warming may increase the range of biofouling animals that are limited by cold temperatures.
In North America, the most troublesome biofoulers include zebra mussels, quagga mussels, Asian clams, and New Zealand mud snails. Strayer notes, "A common theme among these biofoulers is that they are non-native. They are also easily transported on boats and in ballast water. This is a worrisome pattern we are seeing around the world."
Preventing the next global hitchhiker will require vigilance. Strayer stresses that, "Our $277 million dollar estimate is extremely conservative. Right now there is very little research on impacts to freshwater shipping, recreation, and irrigation, or the costs associated with altered freshwater habitat or for biofoulers other than animals. We fully expect the number to rise."
Recommendations include research into understudied freshwater biofoulers, such as sponges and insects, as well as a better understanding of how biofoulers interact with one another, as it is common for multiple species to coexist. Also highlighted is the need for control methods that are both effective and environmentally sensitive, and additional studies on the ecological impacts of biofouler invasions.
When dealing with established biofoulers, improved management is critical. But prevention is the most effective tool. Nakano writes, "At the end of the day, we need education, regulation, and legislation designed to minimize the unintentional global transport of biofouling species."
The Cary Institute of Ecosystem Studies is a private, not-for-profit environmental research and education organization in Millbrook, N.Y. For thirty years, Cary Institute scientists have been investigating the complex interactions that govern the natural world. Their objective findings lead to more effective policy decisions and increased environmental literacy. Focal areas include air and water pollution, climate change, invasive species, and the ecological dimensions of infectious disease.
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The Hubble Heritage Project, which began in October 1998, has released nearly 130 images mined from the Hubble data archive as well as a number of observations taken specifically for the project. By releasing a new, previously unseen Hubble image every month, the team's intent was to showcase some of the most attractive images ever taken by the Hubble telescope, and share them with a wide audience. The Heritage team continues to create aesthetic images that present the universe from an artistic perspective.
This month's three-dimensional-looking Hubble image shows the edge of the giant gaseous cavity within the star-forming region called NGC 3324. The glowing nebula has been carved out by intense ultraviolet radiation and stellar winds from several hot, young stars. A cluster of extremely massive stars, located well outside this image in the center of the nebula, is responsible for the ionization of the nebula and excavation of the cavity.
The image also reveals dramatic dark towers of cool gas and dust that rise above the glowing wall of gas. The dense gas at the top resists the blistering ultraviolet radiation from the central stars, and creates a tower that points in the direction of the energy flow. The high-energy radiation blazing out from the hot young stars in NGC 3324 is sculpting the wall of the nebula by slowly eroding it away.
Located in the Southern Hemisphere, NGC 3324 is at the northwest corner of the Carina Nebula (NGC 3372), home of the Keyhole Nebula and the active, outbursting star Eta Carinae. The entire Carina Nebula complex is located at a distance of roughly 7,200 light-years, and lies in the constellation Carina.
This image is a composite of data taken with two of Hubble's science instruments. Data taken with the Advanced Camera for Surveys (ACS) in 2006 isolated light emitted by hydrogen. More recent data, taken in 2008 with the Wide Field Planetary Camera 2 (WFPC2), isolated light emitted by sulfur and oxygen gas. To create a color composite, the data from the sulfur filter are represented by red, from the oxygen filter by blue, and from the hydrogen filter by green.
The Heritage project has released images using several of Hubble's optical cameras: the Wide Field Planetary Camera (WF/PC), which was installed when the telescope was first deployed in 1990; WFPC2, which replaced WFPC in 1993 and is still in service today; and ACS, which was added in 2002. After the Hubble Servicing Mission in early 2009, the Hubble Heritage team hopes to continue using ACS as well as the newest of the optical cameras, Wide Field Camera 3.
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April has been Mathematics Awareness Month since 1999, making this the nineteenth time it's been observed. Wait, that's not right. The twentieth time. To celebrate our mathematical awareness, or lack thereof, Ken Jennings of Jeopardy! will be with us all month debunking all the popular misinformation about numbers that you thought once you could count on.
The Debunker: How Much Less is .9999… than One?
Like me, you may remember the first time you were asked to perform long division on two numbers that produced a repeating quotient. Do you recall the dreary, slowly dawning realization that these numbers were going to keep repeating in that pattern indefinitely? Even a respectable, friendly, familiar fraction like one-third turned out to be unending in its decimal expansion: 0.333333333333… We were taught to just put a horizontal line over the digit(s) that repeated and call it a day, but it sure wasn’t very satisfying.
But the trouble really starts with .9 repeating: a decimal point followed by an endless string of nines. All levels of students, even including most undergraduate math majors, generally understand that this number is extremely close to 1—"infinitely close," some will allow—but still slightly less. After all, how could 0.999… be the same as 1.0? One begins with a zero and the other with a one. That difference in how they're expressed must reflect some tiny gap between them.
In fact, it's pretty easy to demonstrate intuitively using arithmetic that .9 repeating is exactly equal to 1, not slightly less. If .333… is one-third, and .666… is two-thirds, then obviously .999… is three-thirds, which is to say one, not a number slightly smaller than one. A more formal proof relies on the Archimedean property, which holds that the real numbers have no infinitely large or infinitely small elements, and is a little more involved but still fairly elementary. So why does our intuition insist that there must be a difference between .9 repeating and 1? Way down deep, apparently many of us still expect that .9999999 must stop somewhere; we have a hard time grappling with an endless series of nines. Or we incorrectly think of the series of nines as a process that is advanced as we do our long division, or zoom in on a number line. But that's not how limits work. 0.999999999… isn't infinitely nearing one as we reveal more digits of accuracy. It's already there.
Quick Quiz: Which actor has been Emmy-nominated three times for his role on Brooklyn Nine-Nine?
Ken Jennings is the author of eleven books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings. | <urn:uuid:2ea6c443-9b08-4954-9305-1660bd7fd7b6> | 3.515625 | 611 | Personal Blog | Science & Tech. | 62.235823 | 95,596,767 |
+44 1803 865913
Presents a quantitative treatment of the processes that determine the composition of natural waters. The classic resource on the essential concepts of natural water chemistry.
Chemical Thermodynamics and Kinetics; Acid-Base; Dissolved Carbon Dioxide; Atmosphere-Water Interactions; Metal Ions in Aqueous Solution; Aspects of Coordination Chemistry; Precipitation and Dissolution; Oxidation and Reduction; Equilibria; the Solid-Solution Interface; Trace Metals: Cycling, Regulation and Biological Role; Kinetics and Redox Processes; Photochemical Processes; Kinetics at the Solid-Water Interface; Adsorption; Dissolution of Minerals; Nucleation and Crystal Growth; Particle-Particle Interaction; Colloids; Coagulation and Filtration; Regulation of the Chemical Composition of Natural Waters (Examples); Thermodynamic Data.
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WERNER STUMM is an internationally renowned aquatic scientist at the Federal Institute for Environmental Science and Technology, EAWAG, Swiss Federal Institute of Technology, ETH. His numerous publications include Chemistry of the Solid-Water Interface, Aquatic Chemical Kinetics, and Aquatic Surface Chemistry, all published by Wiley. JAMES J. MORGAN is Marvin L. Goldberger Professor of Environmental Engineering Science at the California Institute of Technology. Professor Morgan was the founding editor of Environmental Science and Technology. He is also a recipient of the American Chemical Society Award for Creative Advances in Environmental Science and Technology.
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This past weekend teams from the National Football League used statistics like height, weight and speed to draft the best college players, and in a few weeks, armchair enthusiasts will use similar measures to select players for their own fantasy football teams. Neuroscientists at Carnegie Mellon University are taking a similar approach to compile “dream teams” of neurons using a statistics-based method that can evaluate the fitness of individual neurons.
After assembling the teams, a computer simulation pitted the groups of neurons against one another in a playoff-style format to find out which population was the best. Researchers analyzed the winning teams to see what types of neurons made the most successful squads.
The results were published in the early online edition of the Proceedings of the National Academy of Sciences the week of April 29.
“We wanted to know what team of neurons would be most likely to perform best in response to a variety of stimuli,” said Nathan Urban, the Dr. Frederick A. Schwertz Distinguished Professor of Life Sciences and head of the Department of Biological Sciences at Carnegie Mellon.
The human brain contains more than 100 billion neurons that work together in smaller groups to complete certain tasks like processing an odor, or seeing a color. Previous work by Urban’s lab found that no two neurons are exactly alike and that diverse teams of neurons were better able to determine a stimulus than teams of similar neurons.
“The next step in our work was to figure out how to assemble the best possible population of neurons in order to complete a task,” said Urban, who is also a member of the joint Carnegie Mellon/University of Pittsburgh Center for the Neural Basis of Cognition (CNBC).
However, using existing methods, scouting for the best team of neurons was a seemingly daunting task. It would be impossible for scientists to determine how each of the billions of neurons in the brain would individually respond to a multitude of stimuli. Urban and Shreejoy Tripathy, the article’s lead author and graduate student in the CNBC’s Program in Neural Computation, solved this problem using a statistical modeling approach, known as generalized linear models (GLMs), to analyze the cell-to-cell variability. Urban and Tripathy found that by applying this approach they were able to accurately reproduce the behavior of individual neurons in a computer, allowing them to gather statistics on each single cell.
Then, much like in fantasy football, the computer model used the statistics to put together thousands of teams of neurons. The teams competed against one another in a computer simulation to see which were able to most accurately recreate a stimulus delivered to the team of neurons. In the end researchers identified a small set of teams that they could study to see what characteristics made those populations successful.
They found that the winning teams of neurons were diverse but not as diverse as they would be if they were selected at random from the general population of neurons. The most successful sets contained a heterogeneous group of neurons that were flexible and able to respond well to a variety of stimuli.
“You can’t have a football team made up of only linebackers. You need linebackers and tight ends, a quarterback and a kicker. But, the players can’t just be random people off of the street; they all need to be good athletes. And you need to draft for positions, not just the best player available. If your best player is a quarterback – you don’t take another quarterback with your first pick,” Urban said. “It’s the same with neurons. To make the most effective grouping of neurons, you need a diverse bunch that also happens to be more robust and flexible than your average neuron.”
Urban believes that GLMs can be used to further understand the importance of neuronal diversity. He plans to use the models to predict how alterations in the variability of neurons’ responses, which can be caused by learning or disease, impact function.
Co-authors of the study also include Carnegie Mellon postdoctoral fellows Richard Gerkin and Krishnan Padmanabhan. The research was funded by the National Science Foundation, the Richard King Mellon Foundation, the National Institutes of Health (F32 DC010535) and the National Institute on Deafness and Other Communication Disorders (R01 DC0005798).
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Rice University study: Flowing water influenced retreat of ancient Antarctic ice sheet
Antarctic researchers from Rice University have discovered one of nature's supreme ironies: On Earth's driest, coldest continent, where surface water rarely exists, flowing liquid water below the ice appears to play a pivotal role in determining the fate of Antarctic ice streams.
This schematic depicts a subglacial Antarctic river and overlying ice sheet. Black lines t1, t2 and t3 show where the ice sheet was grounded to the seafloor during pauses in ice retreat. Rice University researchers used such lines from precise maps of the Ross Sea floor to study how liquid water influenced the ice sheet during a period of its retreat starting about 15,000 years ago.
Credit: L. Prothro/Rice University
The finding, which appears online this week in Nature Geoscience, follows a two-year analysis of sediment cores and precise seafloor maps covering 2,700 square miles of the western Ross Sea. As recently as 15,000 years ago, the area was covered by thick ice that later retreated hundreds of miles inland to its current location. The maps, which were created from state-of-the-art sonar data collected by the National Science Foundation research vessel Nathaniel B. Palmer, revealed how the ice retreated during a period of global warming after Earth's last ice age. In several places, the maps show ancient water courses -- not just a river system, but also the subglacial lakes that fed it.
Today, Antarctica is covered by ice that is in some places more than 2 miles thick. Though deep, the ice is not static. Gravity compresses the ice, and it moves under its own weight, creating rivers of ice that flow to the sea. Even with the best modern instruments, the undersides of these massive ice streams are rarely accessible to direct observation.
"One thing we know from surface observations is that some of these ice streams move at velocities of hundreds of meters per year," said Rice postdoctoral researcher Lauren Simkins, lead author of the new study. "We also know that ice, by itself, is only capable of flowing at velocities of no more than tens of meters per year. That means the ice is being helped along. It's sliding on water or mud or both."
Because of the paucity of information about how water presently flows beneath Antarctic ice, Simkins said the fossilized river system offers a unique picture of how Antarctic water drains from subglacial lakes via rivers to the point where ice meets sea.
"The contemporary observations we have of Antarctic hydrology are recent, spanning maybe a couple decades at best," Simkins said. "This is the first observation of an extensive, uncovered, water-carved channel that is connected to both subglacial lakes on the upstream end and the ice margin on the downstream end. This gives a novel perspective on channelized drainage beneath Antarctic ice. We can track the drainage system all the way back to its source, these subglacial lakes, and then to its ultimate fate at the grounding line, where freshwater mixed with ocean water."
Simkins said meltwater builds up in subglacial lakes. First, intense pressures from the weight of ice causes some melting. In addition, Antarctica is home to dozens of volcanoes, which can heat ice from below. Simkins found at least 20 lakes in the fossil river system, along with evidence that water built up and drained from the lakes in episodic bursts rather than a steady stream. She worked with Rice co-author and volcanologist Helge Gonnermann to confirm that nearby volcanoes could have provided the necessary heat to feed the lakes.
Study co-author John Anderson, a Rice oceanographer and veteran of nearly 30 Antarctic research expeditions, said the size and scope of the fossilized river system could be an eye-opener for ice-sheet modelers who seek to simulate Antarctic water flow. For example, the maps show exactly how ice retreated across the channel-lake system. The retreating ice stream in the western Ross Sea made a U-turn to follow the course of an under-ice river. Simkins said that's notable because "it's the only documented example on the Antarctic seafloor where a single ice stream completely reversed retreat direction, in this case to the south and then to the west and finally to the north, to follow a subglacial hydrological system."
Simkins and Anderson said the study may ultimately help hydrologists and modelers better predict how today's ice streams will behave and how much they'll contribute to rising sea levels.
"It's clear from the fossil record that these drainage systems can be large and long-lived," Anderson said. "They play a very important role in the behavior of the ice sheet, and most numerical models today are not at a state where they can deal with that kind of complexity."
He said another key finding is that drainage through the river system took place on a time scale measured in tens to several hundreds of years.
"We're kind of in this complacent mode of thinking right now," Anderson said. "Some people say, 'Well, the ice margin seems to be stable.' Some people may take comfort in that, but I don't because what this new research is telling us is that there are processes that operate on decadal time scales that influence ice behavior. The probability of us having observed a truly stable condition in the contemporary system, given our limited observation time, is pretty low."
Additional co-authors are Lindsay Prothro of Rice, Sarah Greenwood of Stockholm University, Anna Ruth Halberstadt and Robert DeConto of the University of Massachusetts-Amherst, Leigh Stearns of the University of Kansas and David Pollard of Pennsylvania State University.
The research was supported by the National Science Foundation and the Swedish Research Council.
High-resolution IMAGES are available for download at:
CAPTION: Location of study area in the western Ross Sea. (Image courtesy of L. Simkins/Rice University)
CAPTION: This schematic depicts a subglacial Antarctic river and overlying ice sheet. Black lines t1, t2 and t3 show where the ice sheet was grounded to the seafloor during pauses in ice retreat. Rice University researchers used such lines from precise maps of the Ross Sea floor to study how liquid water influenced the ice sheet during a period of its retreat starting about 15,000 years ago. (Image courtesy of L. Prothro/Rice University)
CAPTION: An example of seafloor bathymetry data that Rice University oceanographers used to identify a paleo-subglacial channel, grounding line landforms, volcanic seamounts and other features used in their study. (Image courtesy of L. Simkins/Rice University)
The DOI of the Nature Geoscience paper is: 10.1038/ngeo3012
A copy of the paper is available at: http://dx.
Related stories from Rice:
Colossal Antarctic ice-shelf collapse followed last ice age -- Feb. 18, 2016 http://news.
Antarctic expert says ice-shelf rifts could threaten glaciers -- Jan. 9, 2017 http://news.
This release can be found online at news.rice.edu.
Follow Rice News and Media Relations via Twitter @RiceUNews
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for quality of life and for lots of race/class interaction and No. 2 for happiest students by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.
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The Ginzburg-Landau Equation as a Model of the Three-Dimensional Circular Cylinder Wake at Low Reynolds Numbers
The circular cylinder wake is a basic problem in fluid dynamics. At low Reynolds numbers, there is a transition from a steady to an oscillatory wake, which has been previously identified (Provansal et al.) as a Landau-Hopf bifurcation by local measurements. However this model is unsufficient to account for the spatial effects along the axis of the cylinder which turned out to be of crude importance. Many observations of spatial structures have been done: inclined vortex shedding (Berger & Wille, Gerrard), cells of different frequencies (Gerich & Eckelmann), influence of end effects and pressure conditions on parallel or oblique vortex shedding (Williamson, Hammache & Gharib).
KeywordsReynolds Number Standard Length Circular Cylinder Critical Reynolds Number Landau Model
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Act IV. Internal Energy: the First Paper of Clausius. Entropy: the First Paper of Rankine
I am not aware, however, that it has been sufficiently proved by experiment that no loss of heat occurs when work is done; it may, perhaps, on the contrary, be asserted with more correctness that even if such a loss has not been proved directly, it has yet been shown by other facts to be not only admissible, but even highly probable. If it be assumed that heat, like a substance, cannot diminish in quantity, it must also be assumed that it cannot increase. It is, however, almost impossible to explain the heat produced by friction except as an increase in the quantity of heat. The careful investigations of Joule, in which heat is produced in several different ways by the application of mechanical work, have almost certainly proved not only the possibility of increasing the quantity of heat in any circumstances but also the law that the quantity of heat developed is proportional to the work expended in the operation. To this it must be added that other facts have lately become known which support the view, that heat is not a substance, but consists in a motion of the least parts of bodies. If this view is correct, it is admissible to apply to heat the general mechanical principle that a motion may be transformed into work, and in such a manner that the loss of vis viva is proportional to the work accomplished.
KeywordsMolecular Theory External Work Isothermal Process Saturated Steam Classical Thermodynamic
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Algebraically, the dot product is the sum of the products of the corresponding entries of the two sequences of numbers. Geometrically, it is the product of the Euclidean magnitudes of the two vectors and the cosine of the angle between them. These definitions are equivalent when using Cartesian coordinates. In modern geometry, Euclidean spaces are often defined by using vector spaces. In this case, the dot product is used for defining lengths (the length of a vector is the square root of the dot product of the vector by itself) and angles (the cosine of the angle of two vectors is the quotient of their dot product by the product of their lengths).
The name "dot product" is derived from the centered dot " · " that is often used to designate this operation; the alternative name "scalar product" emphasizes that the result is a scalar, rather than a vector, which is the case for the vector product in three-dimensional space.
The dot product may be defined algebraically or geometrically. The geometric definition is based on the notions of angle and distance (magnitude of vectors). The equivalence of these two definitions relies on having a Cartesian coordinate system for Euclidean space.
In modern presentations of Euclidean geometry, the points of space are defined in terms of their Cartesian coordinates, and Euclidean space itself is commonly identified with the real coordinate space Rn. In such a presentation, the notions of length and angles are defined by means of the dot product. The length of a vector is defined as the square root of the dot product of the vector by itself, and the cosine of the (non oriented) angle of two vectors of length one is defined as their dot product. So the equivalence of the two definitions of the dot product is a part of the equivalence of the classical and the modern formulations of Euclidean geometry.
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The temperature threshold for melting the ice sheet completely is in the range of 0.8 to 3.2 degrees Celsius global warming, with a best estimate of 1.6 degrees above pre-industrial levels, shows a new study by scientists from the Potsdam Institute for Climate Impact Research (PIK) and the Universidad Complutense de Madrid. Today, already 0.8 degrees global warming has been observed. Substantial melting of land ice could contribute to long-term sea-level rise of several meters and therefore it potentially affects the lives of many millions of people.
The time it takes before most of the ice in Greenland is lost strongly depends on the level of warming. “The more we exceed the threshold, the faster it melts,” says Alexander Robinson, lead-author of the study now published in Nature Climate Change. In a business-as-usual scenario of greenhouse-gas emissions, in the long run humanity might be aiming at 8 degrees Celsius of global warming. This would result in one fifth of the ice sheet melting within 500 years and a complete loss in 2000 years, according to the study. “This is not what one would call a rapid collapse,” says Robinson. “However, compared to what has happened in our planet’s history, it is fast. And we might already be approaching the critical threshold.”
In contrast, if global warming would be limited to 2 degrees Celsius, complete melting would happen on a timescale of 50.000 years. Still, even within this temperature range often considered a global guardrail, the Greenland ice sheet is not secure. Previous research suggested a threshold in global temperature increase for melting the Greenland ice sheet of a best estimate of 3.1 degrees, with a range of 1.9 to 5.1 degrees. The new study’s best estimate indicates about half as much.
“Our study shows that under certain conditions the melting of the Greenland ice sheet becomes irreversible. This supports the notion that the ice sheet is a tipping element in the Earth system,” says team-leader Andrey Ganopolski of PIK. “If the global temperature significantly overshoots the threshold for a long time, the ice will continue melting and not regrow – even if the climate would, after many thousand years, return to its preindustrial state.” This is related to feedbacks between the climate and the ice sheet: The ice sheet is over 3000 meters thick and thus elevated into cooler altitudes. When it melts its surface comes down to lower altitudes with higher temperatures, which accelerates the melting. Also, the ice reflects a large part of solar radiation back into space. When the area covered by ice decreases, more radiation is absorbed and this adds to regional warming.
The scientists achieved their insights by using a novel computer simulation of the Greenland ice sheet and the regional climate. This model performs calculations of these physical systems including the most important processes, for instance climate feedbacks associated with changes in snowfall and melt under global warming. The simulation proved able to correctly calculate both the observed ice-sheet of today and its evolution over previous glacial cycles, thus increasing the confidence that it can properly assess the future. All this makes the new estimate of Greenland temperature threshold more reliable than previous ones.
Article: Robinson, A., Calov, R., Ganopolski, A. (2012): Multistability and critical thresholds of the Greenland ice sheet. Nature Climate Change [doi:10.1038/NCLIMATE1449]
Weblink to the article once it is published: http://dx.doi.org/10.1038/NCLIMATE1449For further information please contact:
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"We have Moon samples from the six widely-space Apollo landing sites, but remote sensing with Chandra can cover a much wider area,” continued Drake. “Its the next best thing to being there, and it’s very fast and cost-effective.”
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University of Cincinnati researchers are blending technology with tradition, as they discover new and improved methods for mapping landscapes.
The research is newly published in the Journal of Applied Geography (Vol. 45, December 2013) by UC authors Jacek Niesterowicz, a doctoral student in the geography department, and Professor Tomasz Stepinski, the Thomas Jefferson Chair of Space Exploration in the McMicken College of Arts and Sciences (A&S).
The researchers say the analysis is the first to use a technology from a field of machine vision to build a new map of landscape types – a generalization of a popular land cover/land use map. Whereas land cover/land use pertains to physical material at, or utilization of, the local piece of Earth’s surface, a landscape type pertains to a pattern or a mosaic of different land covers over a larger neighborhood.
Machine vision is a subfield of computer science devoted to analyzing and understanding the content of images. A role of a machine vision algorithm is to “see” and interpret images as close to human vision interpretation as possible. Previous uses of the technology have focused on medicine, industry and government, ranging from robotics to face detection.
The UC research focused on a very large map of land cover/land use, called the National Land Cover Database 2006, developed by the U.S. Geological Survey.
Niesterowicz says he developed and applied machine vision-based algorithms to map landscape types in an area of northern Georgia that he selected because of the diverse patterns of land cover. The result allowed the researchers to discover and differentiate 15 distinctive landscape types, including separating forests by their domination of different plant species.
“Before now, people would do this mapping by hand, but if you had 10 maps drawn by 10 people, they would all be different,” says Stepinski.
Niesterowicz says the information uncovered by auto-mapping of landscape types would be useful for a number of fields, ranging from geographic research to land management, urban planning and conservation.
“The good thing about this method is that it doesn’t need to be restricted to land cover or other physical variables – it can be applied as well to socio-economic data, such as U.S. Census data, for example,” says Niesterowicz.
“It’s an entirely new way to conduct geographic research,” says Stepinski. “By leveraging technology developed in the field of computer science, it’s possible to make geography searchable by content. Using this technique, for example, we can quickly discover (using Web-based applications on our website) that farms in Minnesota are on average larger than farms in Ohio, and ask why that is.”
The researchers say future research will involve using the method to identify characteristic landscape types (from waterways to forests to regions influenced by human habitation) over the entire United States.
Stepinski adds that longer-term applications could involve comparisons of landscape types of other countries with those of the United States and to identify characteristic patterns of different geographical entities, such as terrain, or human patterns including socioeconomics and race.
The research out of UC’s Space Informatics Lab was supported by funding from a grant from the National Science Foundation (NSF BCS-1147702), the Polish National Science Centre (DEC-2012/07/B/ST6/012206) and by the UC Space Exploration Institute.
The UC Department of Geography’s Space Informatics Lab – created by Stepinski – develops intelligent algorithms for fast and intuitive exploration of large spatial datasets. UC’s Space Exploration Institute, funded by a $20 million gift to the university by an anonymous donor in 2007, supports numerous areas of space exploration research, including research out of the Space Informatics Lab.UC Space Informatics Lab Website
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The Burmese peacock turtle is an aquatic turtle found in the lower reaches of the Ayeyarwady (Irrawaddy) River in southern Myanmar and also possibly found as far north as Mandalay and in the Doke-tha-wady at Shwe sar yan. It has a domed shell that reaches around 9 inches in length. Color ranges from light to dark greenish brown. Its underparts are yellow and it has pale yellow eye-like circles that appear on each scute (bony sections covering the shell), giving it it's name. Two yellow streaks appear on each side of the head.
Burmese peacock turtles are found in rivers, swamps, streams, and ponds. Sometimes they are observed stranded on the land during the dry season. Little is known about the reproductive behavior of this species.
Although the species appears to be abundant and are widely available in local markets, it is listed as endangered with the US FWS. Threats to the species may include habitat degradation and overcapture by the Chinese market for medicinal purposes.
Burmese Peacock Turtle Facts Last Updated: May 9, 2017
To Cite This Page:
Glenn, C. R. 2006. "Earth's Endangered Creatures - Burmese Peacock Turtle Facts" (Online).
Accessed 7/15/2018 at http://earthsendangered.com/profile.asp?sp=475&ID=3.
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Seasonal shifts in the relative importance of local versus upstream sources of phosphorus to individual lakes in a chain
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Water quality in the Yahara chain of lakes in southern Wisconsin has been degraded significantly since European settlement of the region, primarily as a result of anthropogenic nutrient inputs. While all four main lakes (Mendota, Monona, Waubesa, and Kegonsa) have undergone eutrophication, elevated phosphorus and chlorophyll concentrations are particularly pronounced in the smaller lakes at the bottom of the chain (Waubesa and Kegonsa). Due to their short water residence times (2–3 months), these lakes are more responsive to seasonal variability in magnitude and source of phosphorus loading compared with the larger upstream lakes. In 2014, more than 80 % of the phosphorus load to Lake Waubesa passed through the outlet of Lake Monona (situated immediately upstream). However, between mid-May and late October when phosphorus concentrations in Lake Monona were reduced as a result of thermal stratification the upstream load dropped to ~40 % of the total, with the majority of loading during this period coming from Lake Waubesa’s local watershed. Correspondingly, seasonal phosphorus trends in Lake Waubesa during summer are correlated with precipitation, rather than phosphorus concentrations leaving upstream lakes. While phosphorus export from the local watersheds of Lakes Waubesa and Kegonsa is relatively small on an annual time scale, targeted loading reductions in these areas during the summertime will most effectively reduce summertime phosphorus concentrations in these fast-flushing lakes. Understanding the interaction of landscape position, water residence time, and mixing regime can help guide watershed management for water quality improvements in lake chains.
KeywordsLake chain Landscape limnology Phosphorus Eutrophication
This work was funded by the Wisconsin Department of Natural Resources and the National Science Foundation, North Temperate Lakes Long-Term Ecological Research (DEB-0822700). The authors would like to thank Stephen Carpenter and two anonymous reviewers for helpful comments on earlier versions of this manuscript.
- Diebel M, Menuz D, Ruesch A (2013) 1:24 k hydrography attribution data (Draft). Wisconsin Department of Natural Resources. ftp://dnrftp01.wi.gov/geodata/hydro_va_24k/WDNR_Hydro_VA_metadata/hydro_va_documentation.pdf. Accessed 2 Sept 2016
- Magnuson JJ (2002) Three generations of limnology at the University of Wisconsin-Madison. Verh Int Verein Limnol. 28:856–860Google Scholar
- Queimaliños C, Reissig M, Diéguez MdC, Arcagni M, Guevara SR, Campbell L, Càrdenas CS, Rapacioli R, Arribére M (2012) Influence of precipitation, landscape and hydrogeomorphic lake features on pelagic allochthonous indicators in two connected ultraoligotrophic lakes of North Patagonia. Sci Total Environ 427–428:219–228CrossRefPubMedGoogle Scholar
- Steinman AD, Denning R (2006) The role of spatial heterogeneity in the management of freshwater resources. In: Lovett GM, Turner MG, Jones CG, Weathers KC (eds) Ecosystem function in heterogeneous landscapes. Springer, Berlin, pp 367–388Google Scholar
- The Cadmus Group (2011) Total maximum daily loads for total phosphorus and total suspended solids in the rock river basin. Wisconsin Department of Natural Resources. http://dnr.wi.gov/topic/TMDLs/RockRiver/. Accessed 2 Sept 2016
- Vollenweider RA (1969) Possibilities and limits of elementary models concerning the budget of substances in lakes. Arch Hydrobiol 66:1–36Google Scholar | <urn:uuid:ae9c7abe-4bff-49bb-8836-154bcc016120> | 2.828125 | 806 | Academic Writing | Science & Tech. | 22.920968 | 95,596,948 |
The Planetary Society announced that its first LightSail spacecraft will be hitching a ride on an Atlas V rocket from Cape Canaveral in order to test the vehicle's critical functions. This flight will be "a precursor to a second mission slated for 2016." The project is entirely funded by private citizens. More info here.
Solar sailing works by using sunlight for propulsion. When solar photons strike LightSail's reflective Mylar® sails, their momentum is transferred to the spacecraft, gradually accelerating it through space. While the push from photons is miniscule, it is continuous and unlimited. Solar sails can eventually reach greater speeds than those obtained from chemical rockets. LightSail consists of four identical triangular sails attached to four 4-meter booms, resulting in a square solar sail when fully deployed.
The 2015 test flight will not carry the spacecraft high enough to escape Earth's atmospheric drag, and will thus not demonstrate controlled solar sailing. Once in orbit, the spacecraft will go through a checkout and testing period of about four weeks before deploying its solar sails. After the sails unfurl, LightSail will test its attitude control system and study the behavior of the sails for a few days before it is pulled back into the planet's atmosphere. Key images and data on the spacecraft's performance will be sent to ground stations at Cal Poly San Luis Obispo and Georgia Tech.
|"Aspiring astronauts were asked to write a Twitter post, a limerick or a haiku as part of their NASA applications."|
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|“A physicist believes that everything will change in 2017 and extraterrestrial life will finally be discovered.”|
|"We're Going to Mars by 2024."|
|“A company headquartered in Toronto runs a successful affordable mobile phone service in the US.”|
|“Civilisation is a movement, and not a condition, a voyage and not a harbour.”|
|Japanese Robot Serves Ice Cream From Inside a Vending Machine|
|“Lighter, more affordable, personal rapid transit: self-driving bikes.”|
|CaptchaTweet: Write Tweets in Captcha Form|
|Somebody Needs to Build a New Facebook Stat|
|Why, Typewriters Are Alive and Well, Thank you|
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|Facebook, Twitter Users Could Face Insurance Hikes|
|Bizarre Record Covers|
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What's the Problem with LC-MS Metabolomics Screens?
Oct 31 2017 Read 1111 Times
A new study into metabolites has revealed what many researchers previously thought. There are not as many metabolites in a sample as we first thought. This follows a pattern first seen in the human genome, when some scientists predicted that the human genome would contain upwards of 100,000 genes. Once the initial results from the Human Genome Project were published in 2001, scientists could start to revise their estimates. It is now thought that there are around 19,000-20,000 genes coding for proteins in the human body.
Now, work carried out at Washington University in St. Louis implies that the number of metabolites seen in samples and data sets could be significantly smaller than previously estimated. The study — published in Analytical Chemistry — suggests that up to 90% of the peaks seen in E. coli samples could be just noise.
Metabolomics — big study of small molecules
Metabolomics is the study of the substrates and products of metabolism — the chemical changes that occur in cells, tissues and organism because of interactions in a biological system. By studying metabolomics, researchers hope to understand the underlying biochemical activity and determine which genetic or environmental factors affect the changes.
The metabolome is the sum of all the metabolites within a cell or tissue. It is continuously changing since cells are alive. A big difference between genetics and metabolomics — metabolites are not made from building blocks like genes and as such are incredibly chemically diverse. But how many metabolites are there — and are all data points real?
Sorting the signal from the noise
Since researchers started studying metabolomics there has been a conundrum that they couldn’t explain. The number of signals they detected in metabolomics experiments suggested significantly more metabolites that were thought to exist and were found in textbooks. Were all the biochemists wrong and thousands of metabolites were waiting to be discovered? Gary Patti, senior author on the paper:
“Of course, the knee-jerk reaction is to assume that most of the signals that do not return matches in databases correspond to unknown metabolites that have never been reported before.”
Typically, a metabolomics experiment is run using liquid chromatography-mass spectrometry (LC-MS) and reveals thousands of peaks, most cannot be identified. The use of LC-MS to analyse biological samples is discussed in the article, Enhanced Peptide Identification Using Capillary UHPLC and Orbitrap Mass Spectrometry. The missing peaks were assigned to missing metabolites — but are they really missing metabolites?
According to the team from St Louis, in the study on E. coli, all the extra peaks are just noise. Co-author Nathaniel Mahieu stated:
“It turns out that more than 90 percent of the signals we see in E. coli data are essentially noise. This greatly reduces the number of unknown metabolites that we thought we were detecting.”
Which means, we are a little closer to understanding what goes on in our bodies.
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In This Edition Articles - Enhanced Sample Preparation - Identifying Inherent Contamination in Deep Well Microplates - How to Determine Extra Column Dispersion and Extra Column Volume - Th...
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An Introduction to the Special Theory of Relativity
by Robert Katz
Publisher: D. Van Nostrand Company, Inc. 1964
Number of pages: 130
It is the purpose of this book to provide an introduction to the Special Theory of Relativity which is accessible to any student who has had an introduction to general physics and some slight acquaintance with the calculus. Much of the material is at a level suitable for high school students who have had advanced placement in physics and mathematics.
Home page url
Download or read it online for free here:
by Tevian Dray - Oregon State University
This text is intended either as a supplement to a traditional physics course which includes special relativity, or as a textbook for a course in geometry or relativity. It emphasizes the fact that special relativity is just hyperbolic trigonometry.
by Nadia L. Zakamska - arXiv
The main purpose of these notes is to introduce 4-vectors and the matrix notation and to demonstrate their use in solving problems in Special Relativity. The pre-requisites are calculus-based Classical Mechanics and Electricity and Magnetism.
by Rafael Ferraro - arXiv
At the end of the 19th century light was regarded as an electromagnetic wave propagating in a material medium called ether. The speed c appearing in Maxwell's wave equations was the speed of light with respect to the ether...
by A. A. Logunov - arXiv
The book presents ideas by Poincare and Minkowski according to which the essence and the main content of the relativity theory are the following: the space and time form a unique four-dimensional continuum supplied by the pseudo-Euclidean geometry. | <urn:uuid:f35c405c-3536-4d21-a457-4be62e62aa3b> | 3.515625 | 347 | Content Listing | Science & Tech. | 36.800208 | 95,597,002 |
Getting Started with JPA
Download a free PDF tutorial about JPA (Java persistence Application) ,training document material on 6 pages designated to beginners.
JPA is most often used in the context of an server application.
This course examines the use of a JPA standalone application and application server.
The classes that instances can be persistent are called entities in the JPA specification
Table of contents
- Getting Started With JPA
- Mapping Java objects
- Relational database.
- How to use an Entity Manager
- JPA API
- Java Persistence Query language (JPQL)
- Tips and more
- File Size:
- 1,098.51 Kb
- Submitted On:
Take advantage of this course called Getting Started with JPA to improve your Programming skills and better understand JPA.
This course is adapted to your level as well as all JPA pdf courses to better enrich your knowledge.
All you need to do is download the training document, open it and start learning JPA for free.
Programming in ADA, PDF Tutorial
Learn Programming in ADA, a complet PDF Tutorial by Wikibooks contributors.
Struts Framework ,Overview Installation and Setup
Free training material course for Framework Struts ,this pdf tutorial will shows you an overview of this famous Java Framework ,how to install and use it .
This document is about a Java programming ,a free pdf tutorial for beginners a basic knowledge of object-oriented programming is assumed.
Introduction to JPA
Download free Introduction to JPA for Beginners, course tutorial, a PDF file created by Bruce Campbell.
Java Persistence with JPA
This tutorial is a reference guide to provide a framework on how to work with JPA and help you to start your first JPA applications,free PDF training course material on 33 pages . | <urn:uuid:5e1ddb3a-106d-4682-8e8c-19180805b3be> | 2.6875 | 380 | Product Page | Software Dev. | 39.038462 | 95,597,007 |
Researchers at IMBA - Institute of Molecular Biotechnology of the Austrian Academy of Sciences - unveil novel mechanism for gene expression.
DNA in all organisms from yeast to humans encodes the genes that make it possible to live and reproduce. But these beneficial genes make up only 2% of our DNA. In fact, more than two-thirds of our genome is populated by selfish genes that only care about their own replication – so-called genetic parasites.
The protein "Moonshiner" triggers RNA transcription within heterochromatin - depicted as a sea of densely packed histones. Drawing by Beata Mierzwa (beatascienceart.com)
Scattered throughout the genomes of plants, fungi, and animals, they can jump from one genomic location to another. Although they can be important for generating diversity in the genome, they can also cause lethal mutations or sterility.
Just as bacteria use the CRISPR/Cas9 system to identify and cleave viruses invading their DNA, eukaryotic cells have developed various strategies to protect the genome and silence these selfish genetic parasites. Small regulatory RNAs govern many of these genome-defense mechanisms and have also yielded major biotechnological innovations.
Solving an evolutionary “chicken and egg” dilemma
One important pathway that maintains the genomic integrity of animals is the piRNA pathway. This system is active in germ cells and utilizes small snippets of RNA—so called piRNAs—which fit like mirror images onto the transcripts of selfish sequences and thereby initiate silencing with their associated Argonaut proteins.
The Brennecke lab at IMBA has been rigorously exploring these RNA-based self-defense mechanisms in fruit flies, using cutting-edge next generation sequencing. The source of piRNAs is within silenced regions containing the selfish elements. This organization established an evolutionary “chicken and egg” dilemma: How could piRNAs be generated from the very regions that they silence? In their current Nature publication, Brennecke’s lab not only solve this enigma but also describe a completely new mechanism for gene-expression.
Moonshiner: There is always a way around
The newly discovered pathway is centered around a protein called moonshiner. Moonshiner is related to basal transcription factors, and interacts with Rhino, a protein bound to heterochromatin at the selfish genes. Rhino recruits Moonshiner to the heterochromatic region, and Moonshiner initiates assembly of the RNA polymerase II pre-initiation complex, that catalyzes the transcription.
Therefore, gene expression is activated in an otherwise silent region via a different code embedded in histone marks rather than DNA sequence. The findings show that piRNAs are transcribed by bending the classical rules of gene activation, combining elements of standard gene activation with gene silencing.
“The pathway, that is active in the piRNA clusters – where the piRNAs are born – literally hacks the gene machinery by combining two different systems, gene activation with gene silencing, just like furniture can be repurposed by IKEA hacking,” illustrates Peter Andersen, Postdoc at IMBA and first author of the paper. The moonshiner pathway thus reveals how cells can utilize heterochromatin for transcription.
“Cells have developed strategies to bypass conventional pathways. The current findings are not only essential to understand the arm´s race between useful genes and the selfish genes that have shaped and still drive evolutionary processes, they also contribute to understanding gene expression in a holistic way,” says Julius Brennecke, IMBA group leader and last author.
'A heterochromatin-dependent transcription machinery drives piRNA expression', Andersen at al.,
Nature; DOI: 10.1038/nature23482
IMBA - Institute of Molecular Biotechnology is one of the leading biomedical research institutes in Europe focusing on cutting-edge functional genomics and stem cell technologies. IMBA is located at the Vienna Biocenter, the vibrant cluster of universities, research institutes and biotech companies in Austria. IMBA is a subsidiary of the Austrian Academy of Sciences, the leading national sponsor of non-university academic research.
About the Vienna BioCenter
The Vienna BioCenter (VBC) is a leading life sciences location in Europe, offering an extraordinary combination of research, education and business on a single campus. About 1,700 employees, more than 1,300 students, 86 research groups, 17 biotech companies, and scientists from more than 40 nations create a highly dynamic environment.
Mag. Ines Méhu-Blantar | idw - Informationsdienst Wissenschaft
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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The Physics of an MRI Machine.
The Physics of an MRI Machine
There are many physical concepts used in a Magnetic Resonance Imaging, also known as MRI, machine. There are many physical concepts used when an MRI is taken of the body, such as; radio waves, resonance and pulse sequences, magnetic fields being produced and lastly, magnets.
Radio waves much stronger than the magnetic field of the Earth are sent through the body which causes the nuclei in the body to move to a different position. When the nuclei move back to the place they originated from, they send back radio waves that the scanner on the machine picks up and turns them into a picture.
Resonance is very common within multiple branches of physics, without resonance we wouldn’t have television, music or radio. Resonance is also one of the most unexplained phenomenons in physics; it causes glass to break with a high pitched voice, bridges to collapse and also earthquakes causing buildings to collapse. Within the MRI, nuclear magnetic resonance is used, this is when magnetic fields and radio waves cause the atoms in the body to give off tiny radio waves (Bellis). The explanation of Pulse sequences are defined in a basic way by the article “MRI Physics: pulse sequences” as ‘the pulse sequences define the manner in which the radiofrequency pulses, which generate the detectable signals, and magnetic field gradients, which provide the spatial encoding of the signals’ (Sharma). When the pulse sequences are used a sequence diagram is used to show how the sequences will occur during the MRI. There are many different sequences available; each used for creating certain images, the most commonly used is the spin echo sequence.
When magnetic fields are produced, it means an electron has moved along a wire creating a magnetic field around that electron. When the wire is in the form of a loop, or multiple loops in this...
Cited: Bellis, Mary. "Magnetic Resonance Imaging MRI." About.com, Investors. New York Times Company, n.d. Web. 5 June 2012. .
Cluett, Jonathan. "MRI: What is a MRI?." About.com, Orthopedics. New York Times Company, 15 Aug. 2011. Web. 5 June 2012. .
Sharma, Harish, and Jim Lagopoulos. "MRI physics: pulse sequences." Acta Neuropsychiatrica 22.2 (2010): 90. EBSCOhost. Web. 5 June 2012. .
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Research released today helps reveal how human and primate brains process and interpret facial expressions, and the role of facial mimicry in everything from deciphering an unclear smile to establishing relationships of power and status.
The findings were presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.
Facial mimicry — a social behavior in which the observer automatically activates the same facial muscles as the person she is imitating — plays a role in learning, understanding, and rapport. Mimicry can activate muscles that control both smiles and frowns, and evoke their corresponding emotions, positive and negative. The studies reveal new roles of facial mimicry and some of its underlying brain circuitry.
Social status and self-perceptions of power affect facial mimicry, such that powerful individuals suppress their smile mimicry towards other high-status people, while powerless individuals mimic everyone’s smile (Evan Carr, BS, abstract 402.11, see attached summary).
Brain imaging studies in monkeys have revealed the specific roles of different regions of the brain in understanding facial identity and emotional expression, including one brain region previously identified for its role in vocal processing (Shih-pi Ku, PhD, abstract 263.22, see attached summary).
Subconscious facial mimicry plays a strong role in interpreting the meaning of ambiguous smiles (Sebastian Korb, PhD, abstract 402.23, see attached summary).
Another recent finding discussed shows that:
“Today’s findings highlight the role of facial expressions in communication and social behavior,” said press conference moderator Ruben Gur, PhD, of the University of Pennsylvania, an expert on behavior and brain function. “Brain circuits that interpret the face appear ever more specialized, from primate ‘eye cells,’ to brain feedback that enables us to discern meaning through facial mimicry.” This research was supported by national funding agencies, such as the National Institutes of Health, as well as private and philanthropic organizations. Click here to view the full press release.
Kat Snodgrass | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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In optics, the original sense of the word coherence was attributed to the ability of radiation to produce interference phenomena. Today, the notion of coherence is defined more generally by the correlation properties between quantities of an optical field. Usual interference is the simplest phenomenon revealing correlations between light waves.
KeywordsInterference Fringe Light Field Harmonic Wave Spatial Coherence Coherence Function
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- Marathay A. S.: Elements of Optical Coherence Theory ( Wiley, New York 1982 )Google Scholar | <urn:uuid:e0ee6e8c-4de0-45d1-af9e-6931f91254b7> | 2.75 | 388 | Academic Writing | Science & Tech. | 61.476261 | 95,597,029 |
Stormwater is water from rain or melting snow that does not soak into the ground. It flows from rooftops, over paved areas such as driveways, roadways and parking lots. As it flows, stormwater runoff collects and transports animal waste, litter, pesticides, fertilizers, oil & grease, soil and other potential pollutants. Eventually, these stormwater pollutants go directly into streams and rivers with no treatment. This is known as stormwater pollution. | <urn:uuid:41b86dc1-ab9c-4f15-b3e7-987357519b9a> | 3.15625 | 91 | Knowledge Article | Science & Tech. | 44.981 | 95,597,040 |
January 19 2017 Astronomy Newsletter
I don't know what happened to the newsletter after I checked the test version, but here it is - I hope! - formatted properly.
Here's the latest article from the Astronomy site at BellaOnline.com.
Dorado the Mahi Mahi
Since the heavenly flying fish (Volans) is intact, its neighboring constellation Dorado must still be hungry. Dorado is a dolphinfish, mahi mahi being the most common type. Mahi mahi pursue flying fish through tropical seas, and you might imagine Dorado chasing Volans through the southern skies.
*The last man on the Moon*
Neil Armstrong was, famously, the first human to walk on the Moon. There were twelve moonwalkers altogether, and Gene Cernan (1934-2017) was the last one to set foot on the Moon. Besides his career as an astronaut, Cernan was also a naval aviator and aerospace engineer among other things. He died, aged 82, on January 16, leaving only six moonwalkers still alive.
(1) January 16, 2015: the British Beagle 2 lander was found on Mars. It was last heard from on Christmas Day 2003. We now know that the entry, descent and landing sequence worked. However it failed to deploy correctly and was unable to communicate.
(2) January 18, 2002: The Gemini South Observatory was dedicated in Chile. Together with the Gemini North Observatory in Hawaii they give almost complete coverage of the sky.
(3) January 19, 1747: Johann Bode was born. His name lives on in "Bode's Law", but he was also a celestial cartographer who, amazingly, created two influential celestial atlases. http://www.bellaonline.com/articles/art42694.asp
(4) January 19, 1851: Jacobus Kapteyn was born. He was a Dutch astronomer best known for his studies of the Milky Way. He discovered evidence for galactic rotation.
(5) January 19, 2006: NASA's New Horizons spacecraft was launched. It has been past Pluto and its moons, and is now on its way to another Kuiper Belt object.
(6) January 20, 1573: Simon Marius was born. He was a German astronomer who claimed he had seen Jupiter's moons before Galileo. Galileo's documentation was more extensive and published first, but the suggestions Marius made for naming the four large moons were eventually adopted.
(7) January 20, 1930: Edwin "Buzz" Aldrin was born. The second man to step onto the Moon has not only been an astronaut, but also an Air Force combat pilot, aerial gunnery instructor and flight commander. He has a doctorate from MIT and his thesis was on techniques for manned orbital rendezvous. Aldrin remains a passionate advocate of space exploration.
Please visit http://astronomy.bellaonline.com/Site.asp for even more great content about Astronomy. I hope to hear from you sometime soon, either in the forum http://forums.bellaonline.com/ubbthreads.php/forums/323/1/Astronomy or in response to this email message. I welcome your feedback!
Do pass this message along to family and friends who might also be interested. Remember it's free and without obligation. I wish you clear skies.
Mona Evans, Astronomy Editor
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24 March 2010
A slow mind may nurture more creative ideas
AS FAR as the internet or phone networks go, bad connections are bad news. Not so in the brain, where slower connections may make people more creative.
Rex Jung at the University of New Mexico in Albuquerque and his colleagues had found that creativity correlates with low levels of the chemical N-acetylaspartate, which is found in neurons and seems to promote neural health and metabolism.
But neurons make up the brain’s grey matter – the tissue traditionally associated with …
*Free book How to Be Human is only available with annual App + Web and Print + App + Web subscription purchases where subscription delivery is in the United Kingdom, USA, Canada, Australia, New Zealand or Euro area. | <urn:uuid:04ef7971-4167-43a2-93b1-00726e5fb849> | 2.578125 | 155 | Truncated | Science & Tech. | 30.505357 | 95,597,091 |
Washington: Colourful bursts of sprites, which are one of the most indefinable phenomena occurring in earth’s atmosphere, may also flash in outer space, signalling the existence of alien life, a new study has revealed.
Sprites are large electrical discharges that flash high in the upper atmosphere -- usually above powerful lightning storms. Often bright red in colour with streaming tendrils of blue and purple stretching down beneath, they hadn’t even been photographed in colour until 1995, Discovery News reported.
Although sprites are quite common on Earth, they have not been well documented as they occur high in the mesosphere, well above the range of weather balloons.
Researchers at Tel Aviv University have suggested that lightning is not only found in large quantity on Earth but also on other planets in our solar system as well.
Venus has been shown to have Earth like lightning, while Jupiter and Saturn experience lightning a thousand times more powerful than Earth’s.
Daria Dubrovin, along with her team of supervisors and collaborators re-created other planetary atmospheres in the lab to study the presence of extraterrestrial sprites.
Using chemical mixtures that mimic the atmospheres of Venus, Jupiter and Saturn, and electrical circuits that simulate lightning, Dubrovin’s team studied how sprites would be created and what they would look like on other worlds.
“We make sprites-in-a-bottle,” Dubrovin said.
According to Dubrovin, as the sprites are linked to lightning, and lightning plays a major role in defining several theories concerning how life first developed on Earth, it stands to reason that the existence of sprites on other planets (both in our own solar system and others) may be something to watch out for when searching for signs of alien life. | <urn:uuid:9c127ec4-d19e-4baf-9f3f-060f03f0ce99> | 3.5 | 366 | News Article | Science & Tech. | 29.67105 | 95,597,099 |
“This is one of the hottest tools in biology, and we’ve now found a way to target it to any DNA sequence,” said Carlos F. Barbas III, the Janet and Keith Kellogg II Chair in Molecular Biology and Professor in the Department of Chemistry at TSRI.
The breakthrough concerns a set of designer DNA-binding proteins called TALEs, which biologists increasingly use to turn on, turn off, delete, insert or even rewrite specific genes within cells—for scientific experiments and also for potential biotech and medical applications, including treatments for genetic diseases.
TALE-based methods had been considered useful against only a fraction of the possible DNA sequences found in animals and plants, but the new finding removes that limitation.
Barbas and his team report their finding on August 26, 2013 in an advance online edition of the journal Nucleic Acids Research.
Molecular biologists have long dreamed of being able to manipulate DNA in living cells with ease and precision, and by now that dream is nearly a reality. TALE-based designer proteins, introduced just a few years ago, are arguably the most user-friendly and precise DNA-directed tools that have yet been invented.
Designer TALEs (transcription-activator-like effectors) are based on natural TALE proteins that are produced by some plant-infecting bacteria. These natural TALEs help bacteria subvert their plant hosts by binding to specific sites on plant DNA and boosting the activity of certain genes—thereby enhancing the growth and survival of the invading bacteria.
Scientists have found that they can easily engineer the DNA-grabbing segment of TALE proteins to bind precisely to a DNA sequence of interest. Typically they join that DNA-binding segment to another protein segment that can perform some desired function at the site of interest—for example, an enzyme fragment that cuts through DNA. Collectively the Barbas laboratory and others in this field have already engineered thousands of these powerful TALE-based DNA-editing proteins.
However, TALE-based DNA-editing has been seen to have a significant limitation. Virtually all the natural TALE proteins that have been discovered so far target sequences of DNA whose transcription begins with the nucleoside thymidine—the letter “T” in the four-letter DNA code. Structural studies have hinted that natural TALE proteins can’t bind well to DNA without that initial T. Molecular biologists thus have widely assumed that the same “T restriction” rule applies to any artificial TALE protein they might engineer.
“Yet no one has investigated thoroughly whether that initial thymidine is truly required for the variety of TALE designer proteins and enzymes that now exist,” said Brian M. Lamb, a research associate in the Barbas Laboratory who was first author of the new study.
Lamb started by evaluating how well TALE-based proteins function against their usual DNA targets when the first DNA letter is switched from a T to one of the other three nucleosides (A, G or C). Using a library of natural and engineered TALE proteins, he found strong evidence in favor of the “T restriction” rule. “There was an orders-of-magnitude difference—some of the TALE proteins we evaluated lost as much as 99.9% of their activity when we changed that first nucleoside base,” said Lamb.
But he wasn’t ready to give up on the possibility of designing more broadly useful TALE proteins. For this he adapted a “directed evolution” technique developed last year by Andrew C. Mercer, who at the time was a research associate in the Barbas laboratory. First, Lamb generated a large library of novel TALE proteins that vary randomly in the structures they hypothesized to grab the initial nucleoside. He then put these new TALEs through a series of tests, to select—in a speeded up version of natural evolution—those that work adequately even with a non-T nucleoside at the start of their target DNA sequence.
In this way, he found several new TALE protein architectures that aren’t held back by the T restriction. One prefers to bind to DNA that begins not with a T nucleoside but with a G (guanosine). Others bind well enough to sequences that start with any of the four DNA nucleosides. Lamb found that these non-T-restricted TALEs work as designed when conjoined, for example, to DNA-cutting enzyme fragments. “Essentially we abolished the T requirement,” said Lamb.
“That means that the number of DNA sites we can target with TALE-based proteins, and the precision with which we can target within any given gene, have gone up dramatically,” Barbas said.
A Multitude of Potential Uses
He and his team plan to follow up the discovery mostly by using the new unrestricted TALE-based proteins as tools for developing potential gene therapies. But the removal of the “T restriction” on TALE-based DNA editing should have a positive impact also on basic molecular biology, biotechnology, stem cell medicine, and nanotechnology when they are combined for example with DNA origami. Indeed any application that requires the manipulation of DNA in living cells or even the construction of protein-DNA machines should benefit from this breakthrough.
“The number of potential uses of this technology is probably more than any one person can imagine,” Barbas said.The study, “Directed Evolution of the TALE N-Terminal Domain for Recognition of All 5’ Bases,” was funded in part by the National Institutes for Health Pioneer Award (grant DP1CA174426). For see the study, see http://nar.oxfordjournals.org/content/early/2013/08/26/nar.gkt754.full-text-lowres.pdf
Mika Ono | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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Mission Areas L2 Landing Page Tabs
Invasive species have negatively impacted many ecosystems. Invasive reptiles are an increasing problem across the United States. Tracking the establishment and spread of existing and new invasive species is critical to effectively manage invasive species. USGS scientists are developing new tools, particularly molecular techniques, to assist in the early detection of, and rapid response to, ...
The negative effects of invasive Asian carp to the Nation’s waterways are far reaching and have potential to expand and intensify. USGS is delivering data, tools and technologies to partners to keep these invasive fish out of the Great Lakes and other aquatic ecosystems and control them where they occur in the Ohio River and Mississippi River Basins.
The Land Treatment Planning Tool provides a practical resource for managers who are planning restoration and rehabilitation actions on public lands. The tool generates a variety of spatial products while being user friendly for all levels of GIS expertise, even to those with little or no experience.
Marl prairie is the most diverse freshwater vegetation community in the Greater Everglades and provides the only suitable habitat for the federally endangered Cape Sable seaside sparrow (CSSS; Ammodramus maritimus mirabilis).
The Northwestern Atlantic population of loggerhead sea turtles is one of the largest in the world. Genetic studies have divided this population into 5 management units including a genetically distinct group that nests throughout the northern Gulf of Mexico (GoM).
The USGS is incorporating different species and aquatic communities into statistical models to begin developing tools that quantify relationships between flow and total ecosystem services provided by river systems for human benefit.
USGS aquatic scientists develop and adapt new technologies and tools that increase the effectiveness, efficiency, safety, and accuracy of aquatic ecosystem management.
USGS Fisheries scientists work with partners to assess the physiology, life history, reproduction, and habitat needs of aquatic species to assist managers to develop techniques to understand, conserve, and restore fish communities.
USGS scientists quantify and describe functional relationships among aquatic species and habitats to characterize aquatic community structure, function, adaptation, and sustainability.
The central organizing framework for documentation, inventory, monitoring, and study of vegetation in the United States from broad scale formations like forests to fine-scale plant communities. The Classification allows users to produce uniform statistics about vegetation resources across the nation at local, regional, or national levels.
Nature’s Notebook is an online phenological monitoring program that currently supports data collection, storage and use for almost 250 animal species (including fish, insects, reptiles, amphibians, birds and mammals) and 650 plant species (including trees, shrubs, forbs, grasses and cacti). Available to anyone from scientists to nature enthusiast.
This web resource provides decision makers with the information needed to maintain the Upper Mississippi River System as a viable multiple-use large river ecosystem.
The Spring Indices are a suite of models developed to simulate the timing of the onset of spring in native and cultivated plants, as well as other physical and ecological processes, that are primarily sensitive to temperature. The SI can be calculated for any weather station that collects daily minimum and maximum temperatures.
The database houses contemporary and historical data on organismal phenology across the nation. These data are being used in a number of applications for science, conservation and resource management. Customizable data downloads using specific dates, regions, species and phenophases, are freely available.
The ARMI database provides occupancy and abundance estimates at the project level. Data can be accessed in tabular format or plotted directly via an interactive map browser. The trend data is updated annually and is useful for tracking the status of some of our nation’s amphibian populations.
Forest and Rangeland Ecosystem Science Center (FRESC, Corvallis) — The Raptor Information System (RIS) is a computerized literature retrieval system that focuses on raptor management, human impacts on raptors, the mitigation of adverse impacts, and basic raptor biology (with an emphasis on population dynamics and predation).
Breeding Bird Survey (BBS) is a project monitored by the USGS and the Canadian Wildlife Service on the status and trends of North American bird populations. The data can be used to estimate population trends and relative abundances at various scales.
Across Trophic Level System Simulation for the Freshwater Wetlands of the Everglades and Big Cypress Swamp
Across Trophic Level System Simulation (ATLSS) is a project to develop a set of models for the Everglades and Big Cypress Swamp of South Florida. The models will support studies "to compare the future effects of alternative hydrologic scenarios on the biotic components of the system."
The North American Bird Monitoring Projects Database site is dedicated to bird monitoring in North America. It provides easy access to descriptions of all major bird monitoring projects in Canada, the United States, and Mexico.
The North American Bird Phenology Program was a network of volunteer observers who recorded information on first arrival dates, maximum abundance, and departure dates of migratory birds across North America. Active between 1880 and 1970, the program exists now as a historic collection of six million migration card observations.
Modeling intrinsic potential for beaver (Castor canadensis) habitat to inform restoration and climate change adaptation
Through their dam-building activities and subsequent water storage, beaver have the potential to restore riparian ecosystems and offset some of the predicted effects of climate change by modulating streamflow. Thus, it is not surprising that reintroducing beaver to watersheds from which they have been extirpated is an often-used restoration and...Dittbrenner, Benjamin J.; Pollack, Michael M.; Schilling, Jason W.; Olden, Julian D.; Lawler, Joshua J.; Torgersen, Christian E.
Fire and grazing influence site resistance to Bromus tectorum through their effects on shrub, bunchgrass and biocrust communities in the Great Basin (USA)
Shrubs, bunchgrasses and biological soil crusts (biocrusts) are believed to contribute to site resistance to plant invasions in the presence of cattle grazing. Although fire is a concomitant disturbance with grazing, little is known regarding their combined impacts on invasion resistance. We are the first to date to test the idea that biotic...Condon, Lea A.; Pyke, David A.
Golden Eagle Monitoring Plan for the Desert Renewable Energy Conservation Plan
This report describes options for monitoring the status and population trends of the golden eagle (Aquila chrysaetos) within the Desert Renewable Energy Conservation Plan (DRECP) area of Southern California in maintaining stable or increasing population in the planning area. The report profiles the ecology of golden eagles in the region and...Wiens, David; Kolar, Patrick; Katzner, Todd
An analytical framework for estimating aquatic species density from environmental DNA
Environmental DNA (eDNA) analysis of water samples is on the brink of becoming a standard monitoring method for aquatic species. This method has improved detection rates over conventional survey methods and thus has demonstrated effectiveness for estimation of site occupancy and species distribution. The frontier of eDNA applications, however, is...Chambert, Thierry; Pilliod, David S.; Goldberg, Caren S.; Doi, Hideyuki; Takahara, Teruhiko
A simplified field protocol for genetic sampling of birds using buccal swabs
DNA sampling is an essential prerequisite for conducting population genetic studies. For many years, blood sampling has been the preferred method for obtaining DNA in birds because of their nucleated red blood cells. Nonetheless, use of buccal swabs has been gaining favor because they are less invasive yet still yield adequate amounts of DNA for...Vilstrup, Julia T.; Mullins, Thomas D.; Miller, Mark P.; McDearman, Will; Walters, Jeffrey R.; Haig, Susan M.
Assessment of distribution and abundance estimates for Mariana swiftlets (Aerodramus bartschi) via examination of survey methods
We described past and present distribution and abundance data to evaluate the status of the endangered Mariana Swiftlet (Aerodramus bartschi), a little-known echolocating cave swiftlet that currently inhabits 3 of 5 formerly occupied islands in the Mariana archipelago. We then evaluated the survey methods used to attain these estimates via...Johnson, Nathan C.; Haig, Susan M.; Mosher, Stephen M.
Effect of cattle exclosures on Columbia Spotted Frog abundance
Livestock grazing is an important land use in the western USA and can have positive or negative effects on amphibians. Columbia Spotted Frog (Rana luteiventris) often use ponds that provide water for cattle. We conducted a long-term manipulative study on US Forest Service land in northeastern Oregon to determine the effects of full and partial...Adams, Michael J.; Pearl, Christopher; Chambert, Thierry; Mccreary, Brome; Galvan, Stephanie; Rowe, Jennifer
Improving estimation of flight altitude in wildlife telemetry studies
Altitude measurements from wildlife tracking devices, combined with elevation data, are commonly used to estimate the flight altitude of volant animals. However, these data often include measurement error. Understanding this error may improve estimation of flight altitude and benefit applied ecology.There are a number of different approaches that...Poessel, Sharon; Duerr, Adam E.; Hall, Jonathan C.; Braham, Melissa A.; Katzner, Todd
Greater sage-grouse science (2015–17)—Synthesis and potential management implications
Executive SummaryThe greater sage-grouse (Centrocercus urophasianus; hereafter called “sage-grouse”), a species that requires sagebrush (Artemisia spp.), has experienced range-wide declines in its distribution and abundance. These declines have prompted substantial research and management investments to improve the understanding of sage-grouse and...Hanser, Steven E.; Deibert, Patricia A.; Tull, John C.; Carr, Natasha B.; Aldridge, Cameron L.; Bargsten, Travis D.; Christiansen, Thomas J.; Coates, Peter S.; Crist, Michele R.; Doherty, Kevin E.; Ellsworth, Ethan A.; Foster, Lee J.; Herren, Vicki A.; Miller, Kevin H.; Moser, Ann; Naeve, Robin M.; Prentice, Karen L.; Remington, Thomas E.; Ricca, Mark A.; Shinneman, Douglas J.; Truex, Richard L.; Wiechman , Lief A. ; Wilson, Dereck C.; Bowen, Zachary H.
Concentrations of environmental DNA (eDNA) reflect spawning salmon abundance at fine spatial and temporal scales
Developing fast, cost-effective assessments of wild animal abundance is an important goal for many researchers, and environmental DNA (eDNA) holds much promise for this purpose. However, the quantitative relationship between species abundance and the amount of DNA present in the environment is likely to vary substantially among taxa and with...Tillotson, Michael D.; Kelly, Ryan P.; Duda, Jeff; Hoy, Marshal S.; Kralj, James; Quinn, Thomas P.
Mercury concentrations in multiple tissues of Kittlitz's murrelets (Brachyramphus brevirostris)
Mercury (Hg) is a non-essential, toxic metal that is distributed worldwide. Mercury biomagnifies in food webs and can threaten the health of top predators such as seabirds. The Kittlitz's murrelet (Brachyramphus brevirostris) is a seabird endemic to Alaska and the Russian Far East and is a species of conservation concern in the region. We...Kenney, Leah A.; Kaler, Robb S.; Kissling, Michelle L.; Bond, Alexander L.; Eagles-Smith, Collin A.
Occupancy modeling of autonomously recorded vocalizations to predict distribution of rallids in tidal wetlands
Conservation and management for a species requires reliable information on its status, distribution, and habitat use. We identified occupancy and distributions of king (Rallus elegans) and clapper (R. crepitans) rail populations in marsh complexes along the Pamunkey and Mattaponi Rivers in Virginia, USA by modeling data on vocalizations recorded...Stiffler, Lydia L.; Anderson, James T.; Katzner, Todd
USGS scientist Sarah Fitzgerald holds a surf scoter that has been fitted with a satellite tag that works by transmitting the location of the birds to satellites that are orbiting the Earth. (Jonathan Fiely, USGS)
This microscopic image shows a sun-shaped area within turtle skin cells where chelonid herpesvirus 5 replicates. The virus capsids, or protein shells, are arrayed like a corona around the circle. ChHV5 is associated with fibropapillomatosisa tumor disease affecting endangered green turtles. (Credit: Thierry Work,...
- Sea otters are perhaps the best-known example of a "keystone predator".
- Sea otter behavior -- in particular diet specialization and limited mobility -- can mediate their effects on ecosystem dynamics.
- Other predators, especially large sea stars, can complement and reinforce the keystone role of sea otters: this became apparent with the loss of all
Non-native Cuban treefrogs have established a breeding population in New Orleans, Louisiana, the first such population on the U.S. mainland outside Florida. The treefrogs were discovered at the Audubon Zoo shortly after a shipment of palm trees from Florida were planted in the zoo's elephant enclosure in 2016. USGS scientist Brad Glorioso confirmed the presence of a...
Out with the old, in with the new! A state-of-the-art aquatic science laboratory is being built on the shores of Lake Huron at the USGS Hammond Bay Biological Station (HBBS), one of seven field stations of the USGS Great Lakes Science Center, operated in partnership with the Great Lakes Fishery Commission. To make way for the new laboratory, four old buildings on the HBBS...
This single-celled freshwater algae wasa collected as part of the first-ever study of the green algae family called desmids in Florida’s Loxahatchee National Wildlife Refuge, in the northern Everglades. USGS biologist Barry H. Rosen, an expert on freshwater algae who leads the study, used a technique called differential interference microscopy to highlight the relief of...
The public is invited to attend a free, family-friendly open house at a local U.S. Geological Survey center for ecology research on Saturday, September 16.
Suisun Marsh in summer is typically heavy with fog, mosquitoes, and biting flies, but the sun casts sharp light across the water, beating back the usual unpleasantness as WERC volunteer Brock Riggs wades toward a study site on an early July morning.
A non-native insect infestation may not be the only factor involved in the ongoing die-back of a marsh grass in the Mississippi River’s “bird foot delta,” the ecologically and economically important part of coastal Louisiana where the river meets the Gulf of Mexico.
Invasive mussels and less nutrients from tributaries have altered the Lake Michigan ecosystem making it more conducive to the stocking of lake trout and steelhead than Chinook salmon, according to a recent U.S. Geological Survey and Michigan State University study.
Reporters are invited to an event near Fort Collins showcasing cooperative efforts to develop a potential breakthrough in wildlife management – an oral vaccine that may help protect prairie dogs against plague and assist in the recovery of endangered black-footed ferrets at specific locations in the West.
The cold-loving fungus (Pseudogymnoascus destructans, or Pd) that causes white-nose syndrome, a disease that has killed millions of North American bats during hibernation, could also spread in summer months. Bats and humans visiting contaminated caves and mines can inadvertently contribute to the spread of the fungus, according to a recently published study by the U.S. Geological Survey.
In Memoriam - Dr. William "Dave" Woodson, 1956-2017
Direct encounters with humans can increase the likelihood that nesting geese will lose their eggs to predators, according to a recent study released Monday, July 17.
A new study by the U.S. Geological Survey and its partners has identified situations and conditions where some animals display behavioral flexibility – the ability to rapidly change behavior in response to short – or long-term environmental changes such as climate variability.
Lack of Major Hurricanes Since 2008 Is Likely the Main Reason
Forest birds on the island of Hawaii are responding positively to being restored in one of the largest, ongoing reforestation projects at Hakalau Forest National Wildlife Refuge, according to a new study released July 10 in the journal Restoration Ecology.
From the journals of Lewis & Clark, April 13, 1805 (in the vicinity of Pouch Point Recreation Area - 16 miles south of New Town, North Dakota): | <urn:uuid:b6b5a6ba-129f-484f-85a4-60acef8f3073> | 3.265625 | 3,539 | Content Listing | Science & Tech. | 28.418093 | 95,597,119 |
Evidence of climate change isn’t always as stark or far away as melting polar ice caps or rising sea temperatures. In fact, says conservation biologist Richard Primack, unmistakable signs of climate change can be seen every day, in every backyard, in towns across America. Primack, a Boston University professor of biology, is working on an award-winning research project to demonstrate the local effects of global climate change. He’s using Concord, Mass., as a living laboratory, and he has teamed with Henry David Thoreau, America’s great 19th-century nature poet and philosopher, who lived in Concord.
Thoreau identified his occupation as “inspector of snowstorms.” He went out on daily walks and made entries in his journal about what he saw in the landscape around Walden Pond during the 1850s, recording bird migration patterns, flowering cycles of plants, and observations about wildlife and temperature. Primack and his collaborator, Abraham Miller-Rushing, do the same making weekly visits to Concord and taking careful note of when flowers are blooming and when birds are returning each migrating season. Comparing their data with that Thoreau recorded, Primack and Miller-Rushing are showing that global warming is already influencing the behavior of plants and wildlife in Boston and its environs.
“There is a lot of evidence that global climate change is starting to affect biological systems,” says Primack. “A lot of it seems far away, or not immediately serious. What we’re showing is that in one area, one local town, you can see so much evidence of it.” By repeating Thoreau’s experiments and recording the difference in blooming times and in the seasonal appearance of birds, they’ve been able to showcase the effects of a warming climate: on average, they say, “spring events” now begin one week earlier than they did in Thoreau’s time.
“Flowering times are one of the most sensitive indicators of climate change,” Primack says, noting that earlier annual bloom times (and the earlier arrival of birds each spring) correlate to rising annual temperatures. As blooming patterns shift, other processes are affected as well, including pollination and seed dispersal, resulting in potentially dramatic changes to the ecosystem. Thanks to Thoreau’s careful record-keeping, Primack, Miller-Rushing, and their team of undergraduate research assistants can essentially go back in time, making comparisons and drawing conclusions about which plant species are most sensitive to climate change.
“We’re working in a place people can relate to,” Primack says, “and using species that are familiar to people: apple trees, hummingbirds, ducks. It really brings home the message of global climate change.”
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Chromatography in which the immobile phase (bed material) has a specific biological affinity for the substance to be separated or isolated, such as the affinity of an antibody for its antigen, or an enzyme for a substrate analogue.
Affinity chromatography is a method of separating biochemical mixtures based on a highly specific interaction such as that between antigen and antibody, enzyme and substrate, or receptor and ligand. ==Uses== Affinity chromatography can be used to: ==Principle== The stationary phase is typically a gel matrix, often of agarose; a linear sugar molecu...Found on http://en.wikipedia.org/wiki/Affinity_chromatography
(from the article `chromatography`) A technique exhibiting great selectivity, affinity chromatography, was first described by Pedro Cuatrecasas and his coworkers in 1968. In these ... ...known in biochemistry. Examples include enzyme-protein, antigen-antibody, and hormone-receptor binding. A structural feature of an enzyme will ... [...Found on http://www.britannica.com/eb/a-z/a/24
<investigation> A technique of analytical chemistry used to separate and purify a biological molecule from a mixture, based on the attraction of the molecule of interest to a particular ligand which has been previously attached to a solid, inert substance. ... The mixture is passed through a column containing the ligand attached to the statio...Found on http://www.encyclo.co.uk/local/20973
chromatography based on a highly specific biologic interaction such as that between antigen and antibody, enzyme and substrate, or receptor and ligand. Any of these substances, covalently linked to an insoluble support or immobilized in a gel, may serve as the sorbent allowing the interacting substance to be isolated from...Found on http://www.encyclo.co.uk/local/21001
The use of immobilized antibody (or antigen) to select specific antigen (or antibody) from a mixture. The purified ligand is then released by disrupting the antibody–antigen interaction, for example by changing the pH.Found on http://www.roitt.com/glossary.asp
Type: Term Definitions: 1. chromatography where the absorbent has a unique chemical affinity for a particular component of the passing solution. Synonyms: affinity columnFound on http://www.medilexicon.com/medicaldictionary.php?t=17384
No exact match found | <urn:uuid:96f94cc9-210a-4c36-8958-697e7785f629> | 3.515625 | 526 | Structured Data | Science & Tech. | 30.486209 | 95,597,140 |
Aeronautics, Guide to Space, Physics
17 May , 2016 by Matt Williams
Simply put, air resistance (aka. drag) describes the forces that act opposite to an object’s velocity as it travels through an atmosphere
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AS the demand for global, broad-based climate change projections has grown, effectively managing the vast accompanying volumes of data represents a major challenge for computational scientists. In the area of understanding and predicting climate change and extreme weather events, advanced tools are required to securely store, manage, access, analyze, visualize, and process enormous and distributed data sets.
In 2017, Lawrence Livermore researchers received an R&D 100 Award for their work on the Earth System Grid Federation (ESGF)—a virtual, collaborative environment that links climate centers and users around the world to models and data via a computing grid powered by the world’s supercomputing resources and the Internet. ESGF facilitates Earth system science and also provides an essential infrastructure for scientists to evaluate models through a common interface, regardless of the data’s location. Although many large-scale data management systems exist, none rival ESGF’s global accessibility and scientific capability.
ESGF’s roots go back nearly two decades, when Livermore computer scientist Dean N. Williams collaborated with Argonne National Laboratory’s Ian Foster and Steve Hammond at the National Center for Atmospheric Research to apply grid computing to climate science applications that required quickly transferring massive amounts of data. The result was a climate-dedicated cyber environment called the Earth System Grid (ESG), which they used to move data among Department of Energy (DOE) sites.
Before ESG, the climate community comprised various groups and organizations, each with its own methods for creating workflows, generating data file formats and conventions, and storing information. If researchers wanted to study the results from other groups, they first had to spend significant resources converting the data into formats with which they were familiar. This task was no less daunting for Livermore’s Program for Climate Model Diagnosis and Intercomparison (PCMDI), which had been evaluating dozens of climate models from institutions all over the world since 1989.
Using grid computing to facilitate PCMDI activities, the ESG team was able to unify data formats and conventions, collect the standardized climate models, and disseminate the information throughout the climate community. Advancements in data management, distributed data sharing, and model archiving led to the full integration of ESG into PCMDI’s Coupled Model Intercomparison Project Phase 3 (CMIP3), which was extensively used in the fourth assessment report by the Intergovernmental Panel on Climate Change (IPCC). The 2007 Nobel Peace Prize was co-awarded to IPCC for this work.
“CMIP3 was originally thought to consist of 1 terabyte of data. Ultimately, it was 35 times larger. The next phase, which was slated to be 100 terabytes, turned out to be nearly 2 petabytes,” says Williams. “To retrieve data for CMIP3, we sent out massive disk file systems to the climate community that they then shipped back to us. Since this process was not scalable for petabytes of data, we sent our collaborators software rather than disks.” Thus, in 2011, ESGF was born—a federated, distributed archive for Earth system data.
ESGF has become the largest-ever platform for collaborative data on Earth system science. At its heart is a peer-to-peer network of nodes distributed across several countries and united by common protocols and interfaces. Node sites span the globe including at NASA, the National Oceanic and Atmospheric Administration (NOAA), and Lawrence Livermore in the United States; the German Climate Computing Centre, the Institut Pierre Simon Laplace, and the Centre for Environmental Data Analysis in Europe; as well as institutions in Australia, China, and elsewhere abroad.
The federation’s interoperability enables users to access global atmospheric, land, ocean, and sea-ice data generated by satellite, and in situ observations and complex computer simulations. With ESGF’s networks, computers, and software, scientists can access and manage Earth system data more efficiently and robustly through newly developed user interfaces, distributed or local search protocols, federated security, server-side analysis tools, direct connections to high-performance networks, an open computation environment, and other community standards.
To guarantee data validity, ESGF uses quality control algorithms to ensure that the proper formats, units of measure, and conventions are used. Data are also given unique digital object identifiers so information can be tracked back to the source. Making the data easily traceable means researchers can reproduce the models of other researchers to test their repeatability. As models are rerun under different conditions, all variations of the output can be published concurrently to ESGF. The environment also uses versioning, which enables any updates to model data to supersede previous output while at the same time preserving the output history. As a result, data comparisons are possible between various outputs. Williams says, “Now that all these disparate data sets are in one place, scientists can for the first time do comparisons between observations, simulations, and reanalysis data. They can also utilize the data right away.”
Today, ESGF serves more than 25,000 users, including scientists and policymakers, and provides them access to a staggering 5 petabytes of data—and this number is continually increasing. Aside from work performed for IPCC, ESGF also supports at least 25 other projects, including DOE’s new Energy Exascale Earth System Model (E3SM)—the most advanced Earth system model ever created. E3SM is designed to run on future exascale computing systems.
Expanding upon ESGF’s capabilities, developers are now looking into machine learning as a way of searching for important connections, patterns, and occurrences, including those associated with naturally occurring climate oscillations such as an El Niño or La Niña, buried deep within the vast petabytes of data available. Another feature under development would allow ESGF to include other science domains. In a prototype version, ESGF has incorporated epidemiology and hydrology data, enabling researchers to study how changes in climate may affect the spread of disease in certain regions. Williams says, “Putting together these different data sets provides a bigger picture of the world and the potential challenges we face. Economic models and other types of models could also be used in this way. The future of ESGF and this type of modeling are promising.”
Key Words: climate science, Coupled Model Intercomparison Project Phase 3 (CMIP3), data sets, Earth System Grid (ESG), Earth System Grid Federation (ESGF), Energy Exascale Earth System Model (E3SM), federated distributed archive, grid computing, Intergovernmental Panel on Climate Change (IPCC), large-scale data management system, petabyte, Program for Climate Model Diagnosis and Intercomparison (PCMDI).
For further information contact Dean Williams (925) 423-0145 (firstname.lastname@example.org).
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While forest ecosystem classification work in Quebec has traditionally concentrated on inventory and mapping, more effort is now being placed on developing field guides similar to those produced in other Canadian provinces. As part of a project to produce a practical forest ecosystem field guide for the Amos Lowlands Ecological Region in northwestern Quebec, existing sub-regional ecological studies were exploited in order to develop a regional classification of forest ecosystems, or forest stations. Review of four fundamental studies provided a list of 107 ecological phases, each representing a particular combination of forest composition, surface deposit type and moisture regime. A series of silvicultural and environmental interpretations were developed and values for each were attributed to the ecological phases. Cluster analysis was then performed to classify phases into 29 broader units. A large, regional biophysical database which became available later in the project provided a means of validating and effectively modifying the classification. The justifications for using the original approach are discussed.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Development of a Practical Forest Ecosystem Classification from Existing Biophysical Studies: An Approach Used in Northwestern Quebec
Brian D. Harvey
- Springer Netherlands
Fallstudie Überschwemmungskarten/© Thaut Images | Fotolia | <urn:uuid:51222be2-9750-4f80-9406-63058f29a4c6> | 2.8125 | 259 | Knowledge Article | Science & Tech. | -7.950867 | 95,597,172 |
Researchers have taken the next step in the evolution of bacteria-powered energy. For the first time ever, researchers connected nine biological-solar (bio-solar) cells into a bio-solar panel. Then they continuously produced electricity from the panel and generated the most wattage of any existing small-scale bio-solar cells – 5.59 microwatts.
“Once a functional bio-solar panel becomes available, it could become a permanent power source for supplying long-term power for small, wireless telemetry systems as well as wireless sensors used at remote sites where frequent battery replacement is impractical,” said Seokheun “Sean” Choi, an assistant professor of electrical and computer engineering in Binghamton University’s Thomas J. Watson School of Engineering and Applied Science, and co-author of the paper.
Choi is the corresponding author of the paper “Biopower generation in a microfluidic bio-solar panel,” which reported the findings.
“This research could also enable crucial understanding of the photosynthetic extracellular electron transfer processes in a smaller group of microorganisms with excellent control over the microenvironment, thereby enabling a versatile platform for fundamental bio-solar cell studies,” said Choi.
Xuejian Wei, a graduate student in the department, and Hankeun Lee ’15, who will graduate from Binghamton in May, were also authors of the study.
The current research is the latest step in using cyanobacteria (which can be found in almost every terrestrial and aquatic habitat on the planet) as a source of clean and sustainable energy.
Last year, the group took steps toward building a better bio-solar cell by changing the materials used in anodes and cathodes (positive and negative terminals) of the cell and also created a miniature microfluidic-based single-chambered device to house the bacteria instead of the conventional, dual-chambered bio-solar cells.
However, this time the group connected nine identical bio-solar cells in a 3×3 pattern to make a scalable and stackable bio-solar panel. The panel continuously generated electricity from photosynthesis and respiratory activities of the bacteria in 12-hour day-night cycles over 60 total hours.
“Bio-solar cell performance has improved significantly through miniaturizing innovative device architectures and connecting multiple miniature cells in a panel,” the report said.
“This could result in barrier-transcending advancements in bio-solar cells that could facilitate higher power/voltage generation with self-sustainability, releasing bio-solar cell technology from its restriction to research settings, and translating it to practical applications in real-world.”
Even with the breakthrough, a typical “traditional” solar panel on the roof of a residential house, made up of 60 cells in a 6×10 configuration, generates roughly 200 watts of electrical power at a given moment. The cells from this study, in a similar configuration, would generate about 0.00003726 watts.
So, it isn’t efficient just yet, but the findings open the door to future research of the bacteria itself.
“It is time for breakthroughs that can maximize power-generating capabilities/energy efficiency/sustainability,” Choi said.
“The metabolic pathways of cyanobacteria or algae are only partially understood, and their significantly low power density and low energy efficiency make them unsuitable for practical applications. There is a need for additional basic research to clarify bacterial metabolism and energy production potential for bio-solar applications.” | <urn:uuid:a8b3dd65-2da5-481e-bb63-383b1def93f0> | 3.421875 | 758 | News Article | Science & Tech. | 19.086688 | 95,597,191 |
Last winter saw alarmingly warm temperatures stretching from the North Atlantic deep into the Arctic. I wrote about this at the time, all through the winter the coast of Norway, in North Scotland, in Iceland, and as far west as Sweden or St. Petersburg Russia, the weather was at or above the freezing point. A spike of warm air stretched all the way to the North Pole, and I recall seeing reports of above-freezing temperatures, at the North Pole, in the dead of winter. The pattern wasn’t just a rare warm day, but persisted throughout the winter.
One effect of this abnormally warm is a recent report from Svalbard, Norway. An international treasure is held there, at the Svalbard Global Seed Vault. The treasure is an archive of seeds is being kept in a vault drilled deep into a mountain in an eternally frozen permafrost landscape. Those seeds are meant to be held in reserve in case of a global crisis threatening plant species on a global scale. We may need those seeds to survive such a future. The location had been chosen because of its remoteness — it’s on Spitzbergen Island, 1300+ miles above the Arctic Circle — and eternally cold. Seeds were to be able to stay refrigerated naturally with no maintenance, permanently.
Notice the temperatures in various places in the 30’s and 40’s (Farenheit). In Longyearbyen, where the Seed Vault is located, at the time I took this picture it was 16F or well below zero. The timing of this picture was at 2AM UTC, meaning that area was in the middle of the night. Think: What was the daytime temperature?
This is what they want us to believe about the seed vault. That it’s permanently frozen in a permanently wintry landscape. That the seeds will stay frozen until the end of time, and we can tap on those seeds at any time to reboot the global ecology if required.
According to a report in The Guardian, this winter was a little different. Instead of the to-be-expected snow all winter, there was rain, and the permafrost melted. Meltwater got into the entrance tunnel, and officials described it as like a “glacier”. The vault itself did not go above the freezing point, since it is buried deep in the mountain.
Conditions, though, are causing a worry whether the seed vault is truly safe for the envisioned time period. A facility that was supposed to operate unattended is now being monitored 24 hours a day. Staff at the Seed Vault are working on mitigation measures, moving some heat-producing equipment out of the vault, installing pumps, building drainage systems, and so forth. An article on Popular Science has information about that.
In a Wired article, they note that the Arctic is warming at a faster rate than the rest of the planet. It’s not just the seed vault, but the whole Spitsbergen Archipelago, and other areas of the Arctic, that are experiencing abnormal warming.
Isn’t this an example of the changing climate? We’re told to not look at a specific storm or weather event as proof of climate change, but instead to look at long term broad trends. In this case we are seeing not just a day or two of abnormally warm weather in the arctic, and not just a whole winter of abnormally warm weather, but two or three winters in a row of abnormally warm winter weather in the arctic. That’s a clear broad ranging pattern over a long period of time.
Where I live, in the SF Bay Area in California, I have a couple examples that have lasted a few years now. When I moved here the summer weather was generally mild, so mild nobody thought it was necessary to have air conditioners. Before moving here I’d read a “Places Rated” book showing information about each city in the USA. It showed that in the SF Bay Area, only 15% of the houses had air conditioning while in the rest of the country 95% did. A mild climate will do that, because air conditioners simply weren’t required. The last couple summers we’ve had properly hot summers much warmer than when I moved here 27 years ago. The winters have also been abnormally warmer — not that we ever had properly cold winters, but we would routinely see frost on rooftops and so forth. The last few winters there’s been none of that.
- Scott Pruitt resigns as EPA Administrator, proving someone can be too corrupt for Trump - July 5, 2018
- Tesla Model 3 and Zero SR drivers beat REFUEL lap time records in 10th annual REFUEL race - July 4, 2018
- Tesla’s new risk from Trump Administration trade war with China and other countries - June 27, 2018
- Volkswagen I.D. R smashes overall record at Pikes Peak International Hill Climb - June 24, 2018
- Tesla closing a dozen or more former Solar City installation centers in layoffs - June 22, 2018
- Uber test driver in self-driving car in fatality accident was streaming Hulu - June 22, 2018
- Misplaced trust in driver assist (Tesla Autopilot) systems can cause huge problems - June 19, 2018
- Tesla layoffs seen by The Market as a big non-issue - June 19, 2018
- Uber self-driving car fatality: Everyone is to blame - May 26, 2018
- Dept of Energy aims for high speed EV charging network in new Grant program - May 14, 2018 | <urn:uuid:0835b1c8-4a55-4158-a27e-8d6e90c96fa4> | 3.296875 | 1,160 | Personal Blog | Science & Tech. | 55.877376 | 95,597,195 |
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A Guide to Selecting Software Measures and Metrics
Getting Started with Impala: Interactive SQL for Apache Hadoop | <urn:uuid:c7bd0591-4c96-4c95-82f7-48b3121ac58c> | 2.78125 | 280 | Product Page | Software Dev. | 48.659303 | 95,597,209 |
Effect of annealing on the structure of polycrystalline silicon
The photoelectric method of converting solar energy is a promising and environmentally safe way of producing electric power. Sunlight can be converted into electric power by means of solar cells. The present paper concerns a study of polycrystalline silicon plates for the production of solar cells in the initial state and after heat treatment.
KeywordsSolar Cell Polycrystalline Silicon Satellite Peak Crystalline Silicon Solar Cell Segregation Defect
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Miami researchers determine intricacies in hurricane intensification
A new study by researchers at NOAA and CIMAS (Cooperative Institute for Marine and Atmospheric Studies) are modeling data from the 2014 Hurricane Edouard in order to figure out why some storms rapidly intensify while others under similar conditions do not.
Rapid intensification is when the maximum sustained winds of a storm increases to at least 30 knots (35 mph) within a 24 hour period. This intensification occurred with Edouard, going from 40 knots to 70 knots within 24 hours. Edouard began as a tropical low on September 10 off the coast of Africa, before increasing to a tropical depression the next day. On the 12th of September, Edouard was named as a Tropical Storm and continued west across the Atlantic before reaching hurricane status on September 14th. Edouard ended up becoming the first major hurricane to develop in the Atlantic basin since Hurricane Sandy of 2012. This hurricane was heavily studied, as an unmanned aircraft was deployed by a NOAA WP-3D aircraft for the first time ever. In all, four unmanned flights were conducted, helping to determine the eye’s location and wind speeds.
Satellite image of Hurricane Edouard September 16th as a category 3 hurricane.
The study described the struggle between thunderstorm activity within the hurricane and environmental flow in the upper levels of the atmosphere. Normally, the thunderstorms within a hurricane are anchored by the upper level winds. However, Edouard’s thunderstorms intensified rapidly and were stronger than the upper level winds, allowing the thunderstorms to rotate with the hurricane’s spin. This sets up a situation where the winds are working with each other, and flowing in the same direction, aiding in overall sustained wind speeds and allowing for rapid intensification.
Cross-section of a hurricane, showing wind directions and rotation at the surface and aloft.
The National Hurricane Center boasts that their track predictions have dramatically improved in recent years. They are between 30 and 40 percent more accurate than 20 years ago. The real issue has been the extended forecasts, which are usually still off by one category 72 to 120 hours out. Just like in weather forecasting, when you start looking further out than 3-4 days, there are so many factors that could change timing that gets compounded the further you look in time.
Desktop NewsClick to open Continuous News in a sidebar that updates in real-time.
Thief returns special needs girl's stolen tricycle
Road closure this weekend ahead of century-old farmhouse move
Small plane makes emergency landing in Scotlandville Friday; no injuries reported
Southern University police bust a move while filming 'Lipsync Challenge' video
Still no leads in parish-wide cat killings | <urn:uuid:03249225-143d-4ca0-aef4-abb57d0e6215> | 2.75 | 557 | News Article | Science & Tech. | 32.392667 | 95,597,230 |
Seeing where energy goes may bring scientists closer to realizing nuclear fusion
An international team of researchers has taken a step toward achieving controlled nuclear fusion–a process that powers the Sun and other stars, and has the potential to supply the world with limitless, clean energy.
The team, led by scientists and engineers at the University of California, San Diego and General Atomics, developed a new technique to "see" where energy is delivered during a process called fast ignition, which is an approach to initiate nuclear fusion reactions using a high-intensity laser. Visualizing the energy flow enabled researchers to test different ways to improve energy delivery to the fuel target in their experiments. The researchers published their findings online in the Jan. 11 issue of the journal Nature Physics.
Fast ignition involves two stages to start nuclear fusion. First, hundreds of lasers compress the fusion fuel (typically a mix of deuterium and tritium contained in a spherical plastic fuel capsule) to high density. Then, a high-intensity laser delivers energy to rapidly heat (ignite) the compressed fuel. Scientists consider fast ignition a promising approach toward controlled nuclear fusion because it requires less energy than other approaches.
But in order for fast ignition to succeed, scientists need to overcome a big hurdle: how to direct energy from the high-intensity laser into the densest region of the fuel. "This has been a major research challenge since the idea of fast ignition was proposed," said Farhat Beg, professor of mechanical and aerospace engineering and director of the Center for Energy Research at UC San Diego.
To tackle this problem, the team devised a way to see, for the first time, where energy travels when the high-intensity laser hits the fuel target. The technique relies on the use of copper tracers inside the fuel capsule. When the high-intensity laser beam is directed at the compressed fuel target, it generates high-energy electrons that hit the copper tracers and cause them to emit X-rays that scientists can image.
"Before we developed this technique, it was as if we were looking in the dark. Now, we can better understand where energy is being deposited so we can investigate new experimental designs to improve delivery of energy to the fuel," said Christopher McGuffey, assistant project scientist in Beg's High Energy Density Physics Group at the UC San Diego Jacobs School of Engineering and co-author on the paper.
And that's what the team did. After experimenting with different fuel target designs and laser configurations, researchers eventually achieved a record high (up to 7 percent) efficiency of energy delivery from the high-intensity laser to the fuel. This result demonstrates an improvement on efficiency by about a factor of four compared to previous fast ignition experiments, researchers said.
Computer simulations also predicted an energy delivery efficiency as high as 15 percent if the experimental design was scaled up. But this prediction still needs to be tested experimentally, said Beg. "We hope this work opens the door to future attempts to improve fast ignition."
The study was a collaborative effort involving researchers from UC San Diego, General Atomics, the University of Rochester, Lawrence Livermore National Laboratory, Japan's Osaka University, France's University of Bordeaux and the University of Nevada, Reno. Charlie Jarrott, the first author on the paper, conducted this research as a Ph.D. student in Beg's High Energy Density Physics Group at the UC San Diego Jacobs School of Engineering. He is now a postdoctoral research staff member at Lawrence Livermore National Laboratory.
Full paper: "Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets" published Jan. 11 in Nature Physics.
The work was supported by the US Department of Energy National Nuclear Security Agency under the National Laser User Facility programme (award # DE-NA0000854, DE-NA0002033), the OFES Fusion Science Center (grant # DE-FC02-04ER54789), an OFES ACE Fast Ignition grant (DE-FG02-95ER54839), and NNSA cooperative agreement (DE-NA0001944). | <urn:uuid:016e6661-987c-4663-8adb-a6a4b0e249ad> | 3.71875 | 834 | News Article | Science & Tech. | 29.654374 | 95,597,232 |
+44 1803 865913
This volume presents a representative sample of contributions to the 41st European Marine Biology Symposium held in September 2005 in Cork, Ireland. The theme of the symposium was `Challenges to Marine Ecosystems' and this was divided into four sub themes; Genetics, Marine Protected Areas, Global Climate Change and Marine Ecosystems, Sustainable Fisheries and Agriculture.
The world's marine ecosystems face multiple challenges, some natural, but many resulting from humankind's activities. Global climate change, driven by influences of energy usage and industrial practices, is a reality now accepted by most of the world's scientists, media and political establishments. Warming seas and rising sea levels are regarded as threats, while visionaries consider deep ocean carbon disposal as a technological opportunity. Exploitation of the seas continues apace, with repeated concerns over the impact of over-fishing, plus reservations about the environmental effects of marine aquaculture. We need to understand how resilient organisms and ecosystems are to these challenges, while responding by protecting biologically-meaningful areas of the oceans. The subthemes of the 41st European Marine Biology Symposium address all of these matters.
Reprinted from HYDROBIOLOGIA, 606, 2008
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Behavior Genetics of Flexible Life Histories in Milkweed Bugs (Oncopeltus fasciatus)
Insects often face uncertain or unpredictable environments and must make appropriate adjustments in their life histories. Adaptations to predictable environments are well-known, and there is an extensive literature on the use of photoperiod, the most reliable seasonal cue, to time diapause, migration, reproduction and related responses. The difficulty comes when photoperiod (or any other cue) is unreliable. Under such conditions, the best strategy for an organism is to remain flexible, and the most obvious way to do so is via behavior, in particular those behaviors such as migration and diapause that allow choices of where and when to breed. Behavior can thus be an important element of a life history “strategy” (Dingle 1982, 1984).
KeywordsLife History Genetic Correlation Life History Trait Clutch Size Wing Length
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Alistair Lees spends much of his research time hoping to see the light.
Using tools that improve by several orders of magnitude on the accuracy of microscopes and stopwatches, Lees is working at the molecular level to explore the effect of light on chemical systems. The field is called photochemistry and Lees’ efforts could help to find less-expensive ways to produce gasoline, make the environment cleaner and safer, and enhance the quality of microcircuitry and the equipment that relies on it.
While most chemists work with molecules in their ground or normal states, Lees has spent the past two decades working with "excited" molecules, a state attained when molecules absorb light, known as second chemistry.
Ingrid Husisian, Susan E. Barker | dicover-e
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Largest Ever SNP Dataset for the Populus Tree
News Jan 19, 2017 | Original story from the Oak Ridge National Laboratory
Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) have released the largest-ever single nucleotide polymorphism (SNP) dataset of genetic variations in poplar trees, information useful to plant scientists as well as researchers in the fields of biofuels, materials science, and secondary plant metabolism.
For nearly 10 years, researchers with DOE’s BioEnergy Science Center (BESC), a DOE Bioenergy Research Center led by ORNL, have studied the genome of Populus—a fast-growing perennial tree recognized for its economic potential in biofuels production. Today, they released the Genome-Wide Association Study (GWAS) dataset that comprises more than 28 million single nucleotide polymorphisms, or SNPs, derived from approximately 900 resequenced poplar genotypes. Each SNP represents a variation in a single DNA nucleotide, or building block, and can act as a biological marker, helping scientists locate genes associated with certain characteristics, conditions, or diseases.
The data “gives us unprecedented statistical power to link DNA changes to phenotypes [physical traits],” said Gerald Tuskan, a corporate fellow and leader of the Plant Systems Biology group in ORNL’s Biosciences Division. Tuskan will present the GWAS data today at the Plant & Animal Genome Conference in San Diego. The results of this analysis have been used to seek genetic control of cell-wall recalcitrance—a natural characteristic of plant cell walls that prevents the release of sugars under microbial conversion and inhibits biofuels production.
BESC scientists are also using the dataset to identify the molecular mechanisms controlling deposition of lignin in plant structures. Lignin, the polymer that strengthens plant cell walls, acts as a barrier to accessing cellulose and thereby preventing cellulose breakdown into simple sugars for fermentation.
With the new poplar GWAS dataset, “we can identify the genes and genetic variants [i.e. alleles] that move carbon through the lignin pathway, and then take that knowledge and, through genomic selection, develop plant materials that are tailored to work with microbes to yield the targeted product,” Tuskan said. Such products include modified lignin customized for chemicals, polymers and materials. Although the dataset’s most immediate applications are in plant science, ORNL researchers plan to use the GWAS data to inform bioscience work in areas such as cleaner, sustainable transportation fuels, carbon fiber for lightweight vehicles and alternatives to conventional plastics and building insulation materials.
Even the medical field could benefit from the work: ORNL researchers, for instance, have used the poplar GWAS to identify the genes that control callus formation, or cells covering a plant wound. The work has implications for cancer research.
“The genes related to callus formation are analogous to many genes involved in the formation of tumors in humans,” Tuskan said. “This discovery, and the associated gene expression network surrounding such genes, could inform work related to the Cancer Moonshot,” he added, referring to a federal initiative designed to speed progress in cancer research.
Tuskan, who holds a joint appointment at DOE’s Joint Genome Institute in California, found inspiration for the work in the sequencing of the human genome about a decade ago. The researchers recognized how those types of studies could be used to address DOE challenges in carbon sequestration, bioprocessing and materials science.
Tuskan emphasized the importance of technological advances to the work. Sequencing capacity and computational abilities “made the work possible,” he said. “We are working in the big data realm, and fortunately at the national lab we have the platforms and infrastructure to do this type of analysis.”
As part of their work, the researchers used the computational resources available at ORNL through its Compute and Data Environment for Science (CADES) program within ORNL’s Computing and Computational Sciences Directorate, as well as the Titan supercomputer at the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility.
The research also involves monitoring and cataloging phenotypes of poplar trees in regions from southern British Columbia to central California. “None of the sophisticated genomics and computational science would mean anything without the fieldwork. The genetics, the computational science, and measuring and cataloging phenotypes are the three legs of the platform we stand on at BESC,” Tuskan said.
The researchers plan to expand the existing dataset and collaborate with other scientific groups to collect and analyze additional phenotypes.
The dataset is available at: http://bioenergycenter.org/besc/gwas
This article has been republished from materials provided by Oak Ridge National Labratory. Note: material may have been edited for length and content. For further information, please contact the cited source.
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History of supernova observation
The known history of supernova observation goes back to 185 CE, when supernova SN 185 appeared, the oldest appearance of a supernova recorded by humankind. Several additional supernovae within the Milky Way galaxy have been recorded since that time, with SN 1604 being the most recent supernova to be observed in this galaxy.
Since the development of the telescope, the field of supernova discovery has expanded to other galaxies. These occurrences provide important information on the distances of galaxies. Successful models of supernova behavior have also been developed, and the role of supernovae in the star formation process is now increasingly understood.
The supernova explosion that formed the Vela Supernova Remnant most likely occurred 10,000–20,000 years ago. In 1976, NASA astronomers suggested that inhabitants of the southern hemisphere may have witnessed this explosion and recorded it symbolically. A year later, archaeologist George Michanowsky recalled some incomprehensible ancient markings in Bolivia that were left by Native Americans. The carvings showed four small circles flanked by two larger circles. The smaller circles resemble stellar groupings in the constellations Vela and Carina. One of the larger circles may represent the star Capella. Another circle is located near the position of the supernova remnant, George Michanowsky suggested this may represent the supernova explosion as witnessed by the indigenous residents.
In 185 CE, Chinese astronomers recorded the appearance of a bright star in the sky, and observed that it took about eight months to fade from the sky. It was observed to sparkle like a star and did not move across the heavens like a comet. These observations are consistent with the appearance of a supernova, and this is believed to be the oldest confirmed record of a supernova event by humankind. SN 185 may have also possibly been recorded in Roman literature, though no records have survived. The gaseous shell RCW 86 is suspected as being the remnant of this event, and recent X-ray studies show a good match for the expected age.
In 393 CE, the Chinese recorded the appearance of another "guest star", SN 393, in the modern constellation of Scorpius. Additional unconfirmed supernovae events may have been observed in 369 CE, 386 CE, 437 CE, 827 CE and 902 CE. However these have not yet been associated with a supernova remnant, and so they remain only candidates. Over a span of about 2,000 years, Chinese astronomers recorded a total of twenty such candidate events, including later explosions noted by Islamic, European, and possibly Indian and other observers.
The supernova SN 1006 appeared in the southern constellation of Lupus during the year 1006 CE. This was the brightest recorded star ever to appear in the night sky, and its presence was noted in China, Egypt, Iraq, Italy, Japan and Switzerland. It may also have been noted in France, Syria, and North America. Egyptian physician, astronomer and astrologer Ali ibn Ridwan gave the brightness of this star as one-quarter the brightness of the Moon. Modern astronomers have discovered the faint remnant of this explosion and determined that it was only 7,100 light-years from the Earth.
Supernova SN 1054 was another widely observed event, with Arab, Chinese, and Japanese astronomers recording the star's appearance in 1054 CE. It may also have been recorded by the Anasazi as a petroglyph. This explosion appeared in the constellation of Taurus, where it produced the Crab Nebula remnant. At its peak, the luminosity of SN 1054 may have been four times as bright as Venus, and it remained visible in daylight for 23 days and was visible in the night sky for 653 days.
There are fewer records of supernova SN 1181, which occurred in the constellation Cassiopeia just over a century after SN 1054. It was noted by Chinese and Japanese astronomers, however. The pulsar 3C58 may be the stellar relic from this event.
The Danish astronomer Tycho Brahe was noted for his careful observations of the night sky from his observatory on the island of Hven. In 1572 he noted the appearance of a new star, also in the constellation Cassiopeia. Later called SN 1572, this supernova was associated with a remnant during the 1960s.
A common belief in Europe during this period was the Aristotelian idea that the world beyond the Moon and planets was immutable. So observers argued that the phenomenon was something in the Earth's atmosphere. However Tycho noted that the object remained stationary from night to night—never changing its parallax—so it must lie far away. He published his observations in the small book De nova et nullius aevi memoria prius visa stella (Latin for "Concerning the new and previously unseen star") in 1573. It is from the title of this book that the modern word nova for cataclysmic variable stars is derived.
The most recent supernova to be seen in the Milky Way galaxy was SN 1604, which was observed October 9, 1604. Several people, including Johannes van Heeck, noted the sudden appearance of this star, but it was Johannes Kepler who became noted for his systematic study of the object. He published his observations in the work De Stella nova in pede Serpentarii.
Galileo, like Tycho before him, tried in vain to measure the parallax of this new star, and then argued against the Aristotelian view of an immutable heavens. The remnant of this supernova was identified in 1941 at the Mount Wilson Observatory.
The true nature of the supernova remained obscure for some time. Observers slowly came to recognize a class of stars that undergo long-term periodic fluctuations in luminosity. Both John Russell Hind in 1848 and Norman Pogson in 1863 had charted stars that underwent sudden changes in brightness. However, these received little attention from the astronomical community. Finally, in 1866, English astronomer William Huggins made the first spectroscopic observations of a nova, discovering lines of hydrogen in the unusual spectrum of the recurrent nova T Coronae Borealis. Huggins proposed a cataclysmic explosion as the underlying mechanism, and his efforts drew interest from other astronomers.
In 1885, a nova-like outburst was observed in the direction of the Andromeda galaxy by Ernst Hartwig in Estonia. S Andromedae increased to 6th magnitude, outshining the entire nucleus of the galaxy, then faded in a manner much like a nova. In 1917, George W. Ritchey measured the distance to the Andromeda Galaxy and discovered it lay much farther than had previously been thought. This meant that S Andromedae, which did not just lie along the line of sight to the galaxy but had actually resided in the nucleus, released a much greater amount of energy than was typical for a nova.
Early work on this new category of nova was performed during the 1930s by Walter Baade and Fritz Zwicky at Mount Wilson Observatory. They identified S Andromedae, what they considered a typical supernova, as an explosive event that released radiation approximately equal to the Sun's total energy output for 107 years. They decided to call this new class of cataclysmic variables super-novae, and postulated that the energy was generated by the gravitational collapse of ordinary stars into neutron stars. The name super-novae was first used in a 1931 lecture at Caltech by Zwicky, then used publicly in 1933 at a meeting of the American Physical Society. By 1938, the hyphen had been lost and the modern name was in use.
Although supernovae are relatively rare events, occurring on average about once every 50 years in the Milky Way, observations of distant galaxies allowed supernovae to be discovered and examined more frequently. The first supernova detection patrol was begun by Zwicky in 1933. He was joined by Josef J. Johnson from Caltech in 1936. Using a 45-cm Schmidt telescope at Palomar observatory, they discovered twelve new supernovae within three years by comparing new photographic plates to reference images of extragalactic regions.
In 1938, Walter Baade became the first astronomer to identify a nebula as a supernova remnant when he suggested that the Crab Nebula was the remains of SN 1054. He noted that, while it had the appearance of a planetary nebula, the measured velocity of expansion was much too large to belong to that classification. During the same year, Baade first proposed the use of the Type Ia supernova as a secondary distance indicator. Later, the work of Allan Sandage and Gustav Tammann helped refine the process so that Type Ia supernovae became a type of standard candle for measuring large distances across the cosmos.
The first spectral classification of these distant supernovae was performed by Rudolph Minkowski in 1941. He categorized them into two types, based on whether or not lines of the element hydrogen appeared in the supernova spectrum. Zwicky later proposed additional types III, IV, and V, although these are no longer used and now appear to be associated with single peculiar supernova types. Further sub-division of the spectra categories resulted in the modern supernova classification scheme.
In the aftermath of the Second World War, Fred Hoyle worked on the problem of how the various observed elements in the universe were produced. In 1946 he proposed that a massive star could generate the necessary thermonuclear reactions, and the nuclear reactions of heavy elements were responsible for the removal of energy necessary for a gravitational collapse to occur. The collapsing star became rotationally unstable, and produced an explosive expulsion of elements that were distributed into interstellar space. The concept that rapid nuclear fusion was the source of energy for a supernova explosion was developed by Hoyle and William Fowler during the 1960s.
The first computer-controlled search for supernovae was begun in the 1960s at Northwestern University. They built a 24-inch telescope at Corralitos Observatory in New Mexico that could be repositioned under computer control. The telescope displayed a new galaxy each minute, with observers checking the view on a television screen. By this means, they discovered 14 supernovae over a period of two years.
The modern standard model for Type Ia supernovae explosions is founded on a proposal by Whelan and Iben in 1973, and is based upon a mass-transfer scenario to a degenerate companion star. In particular, the light curve of SN1972e in NGC 5253, which was observed for more than a year, was followed long enough to discover that after its broad "hump" in brightness, the supernova faded at a nearly constant rate of about 0.01 magnitudes per day. Translated to another system of units, this is nearly the same as the decay rate of cobalt-56 (56Co), whose half-life is 77 days. The degenerate explosion model predicts the production of about a solar mass of nickel-56 (56Ni) by the exploding star. The 56Ni decays with a half-life of 6.8 days to 56Co, and the decay of the nickel and cobalt provides the energy radiated away by the supernova late in its history. The agreement in both total energy production and the fade rate between the theoretical models and the observations of 1972e led to rapid acceptance of the degenerate-explosion model.
Through observation of the light curves of many Type Ia supernovae, it was discovered that they appear to have a common peak luminosity. By measuring the luminosity of these events, the distance to their host galaxy can be estimated with good accuracy. Thus this category of supernovae has become highly useful as a standard candle for measuring cosmic distances. In 1998, the High-Z Supernova Search and the Supernova Cosmology Project discovered that the most distant Type Ia supernovae appeared dimmer than expected. This has provided evidence that the expansion of the universe may be accelerating.
Although no supernova has been observed in the Milky Way since 1604, it appears that a supernova exploded in the constellation Cassiopeia about 300 years ago, around the year 1667 or 1680. The remnant of this explosion, Cassiopeia A—is heavily obscured by interstellar dust, which is possibly why it did not make a notable appearance. However it can be observed in other parts of the spectrum, and it is currently the brightest radio source beyond our solar system.
In 1987, Supernova 1987A in the Large Magellanic Cloud was observed within hours of its start. It was the first supernova to be detected through its neutrino emission and the first to be observed across every band of the electromagnetic spectrum. The relative proximity of this supernova has allowed detailed observation, and it provided the first opportunity for modern theories of supernova formation to be tested against observations.
The rate of supernova discovery steadily increased throughout the twentieth century. In the 1990s, several automated supernova search programs were initiated. The Leuschner Observatory Supernova Search program was begun in 1992 at Leuschner Observatory. It was joined the same year by the Berkeley Automated Imaging Telescope program. These were succeeded in 1996 by the Katzman Automatic Imaging Telescope at Lick Observatory, which was primarily used for the Lick Observatory Supernova Search (LOSS). By 2000, the Lick program resulted in the discovery of 96 supernovae, making it the world's most successful Supernova search program.
In the late 1990s it was proposed that recent supernova remnants could be found by looking for gamma rays from the decay of titanium-44. This has a half-life of 90 years and the gamma rays can traverse the galaxy easily, so it permits us to see any remnants from the last millennium or so. Two sources were found, the previously discovered Cassiopeia A remnant, and the RX J0852.0-4622 remnant, which had just been discovered overlapping the Vela Supernova Remnant
This remnant (RX J0852.0-4622) had been found in front (apparently) of the larger Vela Supernova Remnant. The gamma rays from the decay of titanium-44 showed that it must have exploded fairly recently (perhaps around 1200 AD), but there is no historical record of it. The flux of gamma rays and x-rays indicates that the supernova was relatively close to us (perhaps 200 parsecs or 600 ly). If so, this is a surprising event because supernovae less than 200 parsecs away are estimated to occur less than once per 100,000 years.
2000 to present
The "SN 2003fg" was discovered in a forming galaxy in 2003. The appearance of this supernova was studied in "real-time", and it has posed several major physical questions as it seems more massive than the Chandrasekhar limit would allow.
First observed in September 2006, the supernova SN 2006gy, which occurred in a galaxy called NGC 1260 (240 million light-years away), is the largest and, until confirmation of luminosity of SN 2005ap in October 2007, the most luminous supernova ever observed. The explosion was at least 100 times more luminous than any previously observed supernova, with the progenitor star being estimated 150 times more massive than the Sun. Although this had some characteristics of a Type Ia supernova, Hydrogen was found in the spectrum. It is thought that SN 2006gy is a likely candidate for a pair-instability supernova. SN 2005ap, which was discovered by Robert Quimby who also discovered SN 2006gy, was about twice as bright as SN 2006gy and about 300 times as bright as a normal type II supernova.
On May 21, 2008, astronomers announced that they had for the first time caught a supernova on camera just as it was exploding. By chance, a burst of X-rays was noticed while looking at galaxy NGC 2770, 88 million light-years from Earth, and a variety of telescopes were aimed in that direction just in time to capture what has been named SN 2008D. "This eventually confirmed that the big X-ray blast marked the birth of a supernova," said Alicia Soderberg of Princeton University.
One of the many amateur astronomers looking for supernovae, Caroline Moore, a member of the Puckett Observatory Supernova Search Team, found supernova SN 2008ha late November 2008. At the age of 14 she had been declared the youngest person ever to find a supernova. However, in January 2011, 10-year-old Kathryn Aurora Gray from Canada was reported to have discovered a supernova, making her the youngest ever to find a supernova. Mr. Gray, her father, and a friend spotted SN 2010lt, a magnitude 17 supernova in galaxy UGC 3378 in the constellation Camelopardalis, about 240 million light years away.
In 2009, researchers have found nitrates in ice cores from Antarctica at depths corresponding to the known supernovae of 1006 and 1054 AD, as well as from around 1060 AD. The nitrates were apparently formed from nitrogen oxides created by gamma rays from the supernovae. This technique should be able to detect supernovae going back several thousand years.
On November 15, 2010, astronomers using NASA's Chandra X-ray Observatory announced that, while viewing the remnant of SN 1979C in the galaxy Messier 100, they have discovered an object which could be a young, 30-year-old black hole. NASA also noted the possibility this object could be a spinning neutron star producing a wind of high energy particles.
On August 24, 2011, the Palomar Transient Factory automated survey discovered a new Type Ia supernova (SN 2011fe) in the Pinwheel Galaxy (M101) shortly after it burst into existence. Being only 21 million lightyears away and detected so early after the event started, it will allow scientists to learn more about the early developments of these types of supernovae.
On January 22, 2014, students at the University of London Observatory spotted an exploding star SN 2014J in the nearby galaxy M82 (the Cigar Galaxy). At a distance of around 12 million light years, the supernova is one of the nearest to be observed in recent decades.
The estimated rate of supernova production in a galaxy the size of the Milky Way is about twice per century. This is much higher than the actual observed rate, implying that a portion of these events have been obscured from the Earth by interstellar dust. The deployment of new instruments that can observe across a wide range of the electromagnetic spectrum, along with neutrino detectors, means that the next such event will almost certainly be detected.
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|url=value (help) on 2011-07-18. Retrieved 2008-12-19.
- Bishop, David (2008-12-19). "Supernova 2008ha in UGC 12682". Rochester Academy of Sciences. Archived from the original on 2010-04-08. Retrieved 2008-12-19.
- Cohen, Tobi (January 3, 2011). "N.B. girl youngest ever to discover a supernova". The Vancouver Sun. Archived from the original on January 6, 2011. Retrieved 2011-01-04.
- "A galactic cloak for an exploding star". ESA/Hubble Picture of the Week. ESA/Hubble. Retrieved 26 February 2015.
- "Ancient supernovae found written into the Antarctic ice". New Scientist (2698). 2009-03-04. Retrieved 2009-03-09. Refers to .
- Perrotto, Trent; Anderson, Janet; Watzke, Megan (November 15, 2010). "NASA'S Chandra Finds Youngest Nearby Black Hole". NASA. Retrieved 2010-11-19.
- Beatty, Kelly (25 August 2011). "Supernova Erupts in Pinwheel Galaxy". Sky & Telescope. Retrieved 26 August 2011
- "Deep Sky Videos". Retrieved 19 March 2012.
- "Supernova 2012aw: the pictures!". Retrieved 19 March 2012.
- "List of Recent Supernovae". Retrieved 8 April 2012.
- "UCL students discover a supernova".
- Hecht, Jeff (June 19, 2006). "Enigmatic object baffles supernova team". NewScientist.com. Retrieved 2009-07-17. | <urn:uuid:e13067ae-48b8-4b57-937d-4def9f5fa75a> | 3.71875 | 7,097 | Knowledge Article | Science & Tech. | 62.461864 | 95,597,273 |
Cocaine is one of the most commonly used (and abused) plant-derived drugs in the world, but we have almost no modern information on how plants produce this complex alkaloid.
Coca plant (Erythroxylum coca) and the molecular structure of cocaine (grey: carbon, blue: nitrogen, red: oxygen, white: hydrogen). Max Planck Institute for Chemical Ecology/ D’Auria, Jirschitzka
Immunolabeling (green areas) of MecgoR, the enzyme catalyzing the penultimate step of cocaine biosynthesis. The picture shows the strong accumulation of the enzyme in a cross section of a very young E. coca leaf, which is still curled around the growing stem tip. Bar: 0,1 mm. Max Planck Institute for Chemical Ecology/ D’Auria, Jirschitzka
Plants commonly produce tropane and other alkaloids for protection against herbivores and other enemies. Species in seven plant families are known to produce tropane alkaloids, including the Brassicaceae (mustard family), Solanaceae (nightshade or potato family) and Erythroxylaceae (coca family). These families are not closely related to each other. For example, it is assumed that the last common ancestor of the Erythroxylaceae and the Solanaceae lived about 120 million years ago. But how similar are the tropane alkaloid biosynthetic pathways in these families? Was there a single original tropane alkaloid pathway which was lost in most other plant families during the course of evolution? Or, did tropane alkaloid biosynthesis arise independently on several different occasions?
Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:7255beba-1b02-4947-a1b8-05fa5c747283> | 3.40625 | 996 | Content Listing | Science & Tech. | 34.928592 | 95,597,282 |
|CNIDARIA : CONICA : Sertulariidae||SEA ANEMONES AND HYDROIDS|
Description: The main stems arise from a basal stolon, and are zig-zag shaped and small, typically only 20mm in length. The main stem is usually unbranched and annulated in the basal region and between each hydrotheca. The hydrothecae are alternate and more widely spaced than in Sertularella rugosa. They are barrel shaped with transverse annulations, the aperture is approximately square shaped, and has a single denticle at each corner. The operculum consists of four flaps. The gonothecae are oval shaped with transverse ridges. The aperture is slightly raised with 3-4 denticles.
Habitat: This species often grows attached to other hydroids or to seaweeds in habitats with strong wave action.
Distribution: Recorded from all around the British Isles.
Similar Species: The main stems are shorter and finer than those of Sertularella rugosa, and the annulations on the hydrothecae are less well-developed but more numerous than in that species.
Key Identification Features:
Distribution Map from NBN: Interactive map : National Biodiversity Network mapping facility, data for UK.
WoRMS: Species record : World Register of Marine Species.
|Picton, B.E. & Morrow, C.C. (2016). Sertularella tenella (Alder, 1856). [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=D6710 Accessed on 2018-07-19
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:1546aba0-c375-4910-bd97-e094ac1be2b4> | 2.90625 | 375 | Knowledge Article | Science & Tech. | 38.647375 | 95,597,289 |
DNA repair mechanism manipulated to delete genes without leaving a scar
Genes may now be deleted without creating a scar in certain strains of Escherichia coli and other microorganisms, thanks to researchers at Agency for Science, Technology and Research (A*STAR) in Singapore . The technique makes it easier to string together several genetic engineering steps without interference caused by a deletion scar.
Scientists currently delete genes by manipulating a process known as homologous recombination. Nucleotide sequences change places with the target gene during homologous recombination and are left behind as a genetic scar, undermining the effectiveness of subsequent deletions. As scars accumulate, the recombination process is more likely to recognize them than the target gene, disrupting the deletion attempt.
The scar-free deletion trick developed by Hua Zhao and colleagues at the A*STAR Institute of Chemical and Engineering Sciences utilizes a natural DNA repair mechanism. Gene duplication events or errors during replication occasionally lead to the formation of a mirrored DNA sequence known as an inverted repeat.
Since the repeated segments in an inverted repeat are complementary, they bind to each other and form a loop structure. While short loops have a biological role, longer loops can damage the genome and are therefore cut out by repair machinery.
“The key insight was the extreme instability of inverted repeats in the E. coli genome, which we and others observed. That prompted us to explore its application in gene deletion,” says Zhao.
To delete a gene, Zhao’s team prepares a DNA fragment, which includes an inverted repeat of part of the target gene. They then insert the fragment into the genome adjacent to the gene. The inverted repeats form a loop, and the repair machinery swoops in to snip them out. Since the repair process does not always happen, the team also engineers a selection marker into the fragment, enabling them to detect colonies in which it has been cut out.
Zhao’s team successfully repeated their method on three different E. coli genes. They also tested inverted repeats of different lengths to determine which worked best. While shorter repeats were less likely to be excised, longer repeats did not integrate into the genome as often.
Engineering E. coli to produce biochemicals often involves the deletion of multiple genes. According to Zhao, approaches presently only allow four genes to be deleted in sequence. “After that, further deletions create trouble because of recombination between the deletion scars. Our new method doesn’t introduce scars, so recombination won’t be a problem for multiple deletions.”
The A*STAR-affiliated researchers contributing to this research are from the Institute of Chemical and Engineering Sciences
Tear, C. Y., Lim, C. & Zhao, H. Excision of unstable artificial gene-specific inverted repeats mediates scar-free gene deletions in Escherichia coli. Applied Biochemistry and Biotechnology 175, 1858–1867 (2015).
Original article from A*STAR Research
A*STAR Research | Research SEA
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
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19.07.2018 | Life Sciences | <urn:uuid:823fab21-f1bf-43d0-be8e-0be4e3f1f5b6> | 3.625 | 1,255 | Content Listing | Science & Tech. | 36.96988 | 95,597,294 |
MIT biologists have provoked soil-dwelling bacteria into producing a new type of antibiotic by pitting them against another strain of bacteria in a battle for survival.
The antibiotic holds promise for treatment of Helicobacter pylori, which causes stomach ulcers in humans. Also, figuring out the still murky explanation for how the new antibiotic was produced could help scientists develop strategies for finding other new antibiotics.
The work is reported in the February issue of the Journal of the American Chemical Society.
A combination of luck, patience and good detective work contributed to the discovery of the new antibiotic, according to Philip Lessard, research scientist in Professor Anthony Sinskey's laboratory at MIT.
Sinskey's lab has been studying Rhodococcus, a type of soil-dwelling bacteria, for many years. While sequencing the genome of one Rhodococcus species, the researchers noticed that a large number of genes seemed to code for secondary metabolic products, which are compounds such as antibiotics, toxins and pigments.
However, Rhodococcus does not normally produce antibiotics. Many bacteria have genes for antibiotics that are only activated when the bacteria are threatened in some way, so the researchers suspected that might be true of Rhodococcus.
Kazuhiko Kurosawa, a postdoctoral associate in the Department of Biology, decided to try to provoke the bacteria into synthesizing antibiotics by placing them in stressful environments. He tried turning the temperature up and down, then altered the bacteria's growth medium, but nothing worked.
Kurosawa then decided to stress the Rhodococcus bacteria by forcing them to grow in the presence of a competing bacteria, a strain of Streptomyces. Streptomyces produces an antibiotic that normally kills other bacteria, but in one of the experimental test tubes, Rhodococcus started producing its own antibiotic, which wiped out the Streptomyces.
The researchers isolated the antibiotic, dubbed it rhodostreptomycin, and started testing it to see what else it would kill. It proved effective against many other strains of bacteria, most notably Helicobacter pylori. Rhodostreptomycin is a promising candidate to treat H. pylori because it can survive in very acidic environments such as the stomach.
The antibiotic turned out to be a type of molecule called an aminoglycoside, composed of peculiar sugars, one of which has a ring structure that has not been seen before. The ring structure could offer chemists a new target for modification, allowing them to synthesize antibiotics that are more effective and/or stable.
"Even if (rhodostreptomycin) is not the best antibiotic, it provides new structures to make chemical derivatives of," said Lessard. "This may be a starting point for new antibiotics."
One mystery still to be solved is why Rhodococcus started producing this antibiotic. One theory is that the presence of the competing strain of bacteria caused Rhodococcus to "raise the alarm" and turn on new genes.
The version of Rhodococcus that produces the antibiotic has a "megaplasmid," or large segment of extra DNA, that it received from Streptomyces. A logical conclusion is that the plasmid carries the gene for rhodostreptomycin, but the researchers have sequenced more than half of the plasmid and found no genes that correlate to the antibiotic.
Another theory is that the plasmid itself served as the "insult" that provoked Rhodococcus into producing the antibiotic. Alternatively, it is possible that some kind of interaction of the two bacterial genomes produced the new antibiotic.
"Somehow the genes in the megaplasmid combined with the genes in Rhodococcus and together they produced something that neither parent could make alone," said Lessard.
If scientists could figure out how that happens, they could start to manipulate bacterial genomes in a more methodical fashion to design new antibiotics.
Other authors of the paper are T.G. Sambandan, research scientist in MIT's Department of Biology, MIT professors Anthony Sinskey of biology and ChoKyun Rha of the Biomaterials Science and Engineering Laboratory, and Ion Ghiviriga and Joanna Barbara of the University of Florida.
The research was funded by the Cambridge-MIT Institute and the Malaysia-MIT Biotechnology Partnership Program.
Written by Anne Trafton, MIT News Office
Elizabeth A. Thomson | MIT News Office
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
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20.07.2018 | Materials Sciences | <urn:uuid:bb4f3b24-297e-4426-9360-42deb0822048> | 4.21875 | 1,490 | Content Listing | Science & Tech. | 29.908087 | 95,597,304 |
The technique used to study the genome, which contains all the genes on 46 chromosomes, is called array CGH. The use of higher resolution techniques, such as array CGH and, soon, whole genome sequencing, will enhance the ability of researchers to examine stem cell lines to determine which are best – least likely to result in diseases and other problems – to use in creating therapies for use in humans.
Array CGH provided a much better look at the gene content on the chromosomes of human embryonic stem cells, with a resolution about 100 times better than standard clinical methods. Clinical specialists commonly generate a karyotype to examine the chromosomes of cancer cells or for amniocentesis in prenatal diagnosis, which has a much lower resolution than Array CGH, said Michael Teitell, a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research and the senior author of the study. Small defects that could result in big problems later on could be missed using karyotyping for stem cells.
“Basically, this study shows that the genetic makeup of individual human embryonic stem cell lines is unique in the numbers of copies of certain genes that may control traits and things like disease susceptibility,” said Teitell, who also is an associate professor of pathology and laboratory medicine and a researcher at UCLA’s Jonsson Comprehensive Cancer Center. “So, in choosing stem cell lines to use for therapeutic applications, you want to know about these differences so you don’t pick a line likely to cause problems for a patient receiving these cells.”
The study appears in the March 27, 2008 express edition of the journal Stem Cells.
Differences between individual DNA sequences provide the basis for human genetic variability. Forms of variation include single DNA base pair alterations, duplications or deletions of genes or sets of genes, and translocations, a chromosomal rearrangement in which a segment of genetic material from one chromosome becomes heritably linked to another chromosome. These changes can be benign, but they can also promote diseases such as certain cancers, or confer increased risk to other diseases, such as HIV infection or certain types of kidney ailments.
In this study, Teitell and his team sought to determine copy number variants (CNVs), or differences in the numbers of certain genes, in two embryonic stem cell lines. The CNVs provide a unique genetic fingerprint for each line, which can also indicate relatedness between any two stem cell lines. Teitell used embryonic stem cell lines that made different types of neurons and studied them with array CGH for comparison. His team found CNV differences between the two lines in at least seven different chromosome locations below the level of detection using standard karyotype studies. Such differences could impact the therapeutic utility of the lines and could have implications in disease development. More studies will be required to determine the effect of specific CNVs in controlling stem cell function and disease susceptibility, he said.
“In studying embryonic stem cell lines in the future, if we find differences in regions of the genome that we know are associated with certain undesirable traits or diseases, we would choose against using such stem cells, provided safer alternative lines are available,” Teitell said.
Large genome-wide association studies are underway in a variety of diseases to determine what genetic abnormalities might be at play. When the genetic fingerprint or predisposing genes for a certain disease is discovered, it could be used as key information in screening embryonic stem cell lines.
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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03.07.2018 | Event News
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20.07.2018 | Materials Sciences | <urn:uuid:2c37ed53-7c87-46cd-bab4-c3bf055272e5> | 3.234375 | 1,290 | Content Listing | Science & Tech. | 33.316986 | 95,597,305 |
Washington: In what could quench the thirst of billions of people in the future, researchers have discovered our planet`s largest water reservoir 640 km beneath our feet - bound up in rock deep in the earth`s mantle.
Researchers from Northwestern University and University of New Mexico have found deep pockets of magma located beneath North America, a likely signature of the presence of water at these depths.
This water is not in a form familiar to us - it is not liquid, ice or vapour.
This fourth form is water trapped inside the molecular structure of the minerals in the mantle rock.
The discovery suggests water from the earth`s surface can be driven to such great depths by plate tectonics, eventually causing partial melting of the rocks found deep in the mantle.
"We are finally seeing evidence for a whole-earth water cycle that may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades," explained geophysicist Steve Jacobsen from Northwestern University.
Scientists have long speculated that water is trapped in a rocky layer of the earth`s mantle located between the lower mantle and upper mantle.
Jacobsen and seismologist Brandon Schmandt from University of New Mexico provided the first direct evidence that there may be water in this area of the mantle, known as the "transition zone," on a regional scale.
The findings converged to produce evidence that melting may occur about 640 km deep in the earth.
"H2O stored in mantle rocks, such as those containing the mineral ringwoodite, likely is the key to the process," researchers said.
Discovered this year from inside a diamond brought up from a depth of 640 km by a volcano in Brazil, a tiny piece of blue-coloured ringwoodite contained a surprising amount of water bound in solid form in the mineral.
"Melting of rock at this depth is remarkable because most melting in the mantle occurs much shallower, in the upper 80 km," Schmandt said.
If just one percent of the weight of mantle rock located in the transition zone is H2O, that would be equivalent to nearly three times the amount of water in our oceans.
The findings, published in the journal Science, will aid scientists in understanding how the earth formed, what its current composition and inner workings are and how much water is trapped in mantle rock. | <urn:uuid:f2360707-58d0-4393-8db6-1d57a9cf683f> | 3.65625 | 492 | News Article | Science & Tech. | 41.001742 | 95,597,312 |
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Octave/Matlab programs for processing and plotting 2D and 3D Ground Penetrating Radar data Octave is freely available from https://www.gnu.org/software/octave/
Supported by the National Science Foundation under grant EAR-1550732.
Check out the documentation GPR-O
The easiest way of installing the software is via git. You can obtain git from https://git-scm.com/download/
Once git is installed installed, open a Command Prompt window, switch to the folder in which you would like to install GPR-O, and run
git clone https://github.com/NSGeophysics/GPR-O.git
This will download all the scripts and subfolders and will allow you to easily update the software at a later point
Alternatively, you can just download a zipped version by clicking on "Clone or download" and then "Download ZIP". Once you unzipped the file on your computer, the folder will be named "GPR-O-master". I recommend renaming it to "GPR-O".
After cloning or unzipping the software package, change directory into its main folder
and open Matlab or Octave.
In Matlab or Octave, run the setup script
This will set up the folder structure and download some additional data files.
Running under Matlab
After starting Matlab, switch into the GPR-O folder and run in Matlab
Running under Octave
After starting Octave, switch into the GPR-O folder and run in Octave
Keeping GPR-O updated
If you used git to clone the software (instead of downloading a zipped folder), you can update GPR-O by running in a terminal or command prompt:
git pull origin master | <urn:uuid:bbbc7171-f3f1-4459-a859-55055d53597f> | 2.625 | 414 | Documentation | Software Dev. | 49.406926 | 95,597,314 |
The problem the physicists addressed is how a fundamental particle in matter loses track of its quantum mechanical properties through interactions with its environment.
The research was performed by scientists at the California NanoSystems Institute at the University of California, Santa Barbara and the U. S. Department of Energy Ames Laboratory in Iowa.
At the quantum level things like particles or light waves behave in ways very different from what scientists expect in a human-scale world. In the quantum world, for example, an electron can exist in two places at the same time, what is called a "superposition" of states, or spin up and down at the same time.
Quantum mechanics in computing could lead to communication with no possible eavesdropping, lightning-fast database searches, and code-cracking ability.
The answer to the problem the researchers have tackled is key to unraveling how the classical world in which we live emerges from all the interacting quantum particles in matter. This scientific query surrounds the basic quantum dynamics of a single particle spin coupled to a collection, or bath, of random spins. This scenario describes the underlying behavior of a broad class of materials around us, ranging from quantum spin tunneling in magnetic molecules to nuclear magnetic resonance in semiconductors.
“We were stunned by these unexpected experimental results, and extremely excited by the ability to control and monitor single quantum states, especially at room temperature,” said author David Awschalom, a professor of physics at UC Santa Barbara. Awschalom is affiliated with the California NanoSystems Institute at UCSB and is the Director of the Center for Spintronics & Quantum Computation, also at the university.
Recently the issue of how fundamental particles lose track of quantum mechanical properties through interaction with the environment has gained crucial importance in the field of quantum information. In this area, robust manipulation of quantum states promises enormous speedups over classical computation. Keeping track of the quantum phase is essential for keeping the quantum information, and insight into loss of the phase will greatly help to mitigate this process.
Experimental work on this subject has thus far been hindered by the lack of high-fidelity coherent control of a single spin in nature and our inability to directly influence the bath dynamics.
In a collaboration between physicists in Awschalom’s research group at UCSB and Slava Dobrovitski, a visiting scientist from Ames Laboratory in Iowa, a series of experiments were undertaken that utilized electron spins in diamond to investigate different regimes of spin-bath interactions, and provide much information about the decoherence dynamics.
The scientists use diamond crystals to study a single electron spin tied to an adjustable collection of nearby spins. Two features of diamond that make this system viable for unprecedented investigations into the coherent dynamics are the precise optical control of a single spin that is unique to diamond, and the magnetic tunability of the spin-bath and intrabath dynamics with small permanent magnets. Their team’s observations contain a number of extraordinary discoveries, such as the time-dependent disappearance and reappearance of quantum oscillations of the spins in the diamond lattice.
“To our surprise, when looking at longer times, the oscillations disappeared then re-appeared,” said co-author Ronald Hanson, a postdoctoral student at UCSB during this period who is now a professor at the Kavli Institute of Nanoscience Delft, at Delft University of Technology, in the Netherlands. “At first it looked like an artifact, but repeated measurements reproduced this behavior.”
The problem of a single spin coupled to a bath of spins has been the subject of an intense international research effort, as this conceptual framework describes the physical behavior of a number of real systems. Among others, these include atomic and electronic spins that are prime candidates for implementing quantum information processors and coherent spintronics devices.
A series of direct experiments coupled to theoretical simulations demonstrate that spins in diamond serve as a nearly ideal, adjustable, model of central spin.
“This work demonstrates a rare level of synergy between experiment, analytical theory, and computer simulations,” said Dobrovitski. “These three constituents all agree, support, and complement each other. Together, they give a lucid qualitative picture of what happens with spin centers in diamond, and, at the same time, provide a quantitatively accurate description. This agreement is hard to anticipate in advance for such complex systems, where many nuclear and electron quantum spins interact with each other.”
Studies of the quantum dynamics of spins in diamond is an emerging topic involving several leading research groups worldwide. It may also be important in the context of recent interest in possible carbon-based electronic devices employing carbon nanotubes and/or graphene.
Gail Gallessich | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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