Posts by AltonParrish:
Black Holes: Gravity is about to get bumpy
June 9th, 2014
By Perimeter Institute of Theoretical Physics.
New research at Perimeter shows that gravitational fields around black holes might eddy and swirl.
Fasten your seatbelts – gravity is about to get bumpy.
Of course, if you’re flying in the vicinity of a black hole, a bit of extra bumpiness is the least of your worries. But it’s still surprising. The accepted wisdom among gravitational researchers has been that spacetime cannot become turbulent. New research from Perimeter, though, shows that the accepted wisdom might be wrong.
The researchers followed this line of thought: Gravity, it’s thought, can behave as a fluid. One of the characteristic behaviours of fluids is turbulence – that is, under certain conditions, they don’t move smoothly, but eddy and swirl. Can gravity do that too?
Perimeter Faculty member Luis Lehner explains why it might make sense to treat gravity as a fluid. “There’s a conjecture in physics – the holographic conjecture – which says gravity can be described as a field theory,” he says. “And we also know that at high energies, field theories can be described with the mathematical tools we use to describe fluids. So it’s a two-step dance: gravity equals field theory, and field theory equals fluids, so gravity equals fields equals fluids. That’s called the gravity/fluids duality.”
The gravity/fluids duality is not new work – it’s been developing over the past six years. But hidden at the heart of it is a tension. If gravity can be treated as a fluid, then what about turbulence?
“For many years, the folklore among physicists was that gravity could not be turbulent,” notes Lehner. The belief was that gravity is described by a set of equations that are sufficiently different from fluid dynamics equations, such that there would not be turbulence under any circumstances.
Lehner highlights the emerging paradox: “Either there was a problem with the duality and gravity really can’t be fully captured by a fluid description, or there was a new phenomenon in gravity and turbulent gravity really can exist.” A team of researchers – Lehner, Huan Yang (Perimeter and the Institute for Quantum Computing), and Aaron Zimmerman (Canadian Institute for Theoretical Astrophysics) – set out to find out which.
They had hints about what directions to go. Previous simulations at Perimeter, and independent work out of MIT, had hinted that there could be turbulence around the non-realistic case of black holes confined in anti-de Sitter space. “There might be turbulence if you confine gravity in a box, essentially,” says Lehner. “The deeper question is whether this can happen in a realistic situation.”
The team decided to study fast-spinning black holes, because a fluid-dynamics description of such holes hints that the spacetime around them is less viscous than the spacetime around other kinds of black holes. Low viscosity increases the chance of turbulence – think of the way water is more swirly than molasses.
The team also decided to study non-linear perturbations of the black holes. Gravitational systems are rarely analyzed at this level of detail, as the equations are fiendishly complex. But, knowing that turbulence is fundamentally non-linear, the team decided a non-linear perturbation analysis was exactly what was called for.
They were stunned when their analysis showed that spacetime did become turbulent.
“I was quite surprised,” says Yang, who has been studying general relativity (GR) – Einstein’s theory of gravity – since his PhD. “I never believed in turbulent behaviour in GR, and for good reason. No one had ever seen it in numerical simulations, even of dramatic things like binary black holes.”
“Over the past few years, we have gone from a serious doubt about whether gravity can ever go turbulent, to pretty high confidence that it can,” says Lehner.
How did this behaviour hide until now? “It was hidden because the analysis needed to see it has to go to non-linear orders,” says Yang. “People didn’t have enough motivation to do a non-linear study. But, this time, we knew what we were looking for. It gave us the motivation to do a more in-depth study. We had a target and we hit it.”
This is theoretical work, but it might not stay that way. There are next-generation detectors about to come online which might soon be able to detect gravitational waves – ripples in the gravitational “fluid” that result from big events like the collision of two black holes. If gravitation can be turbulent, then those ripples might be a bit different than previous models suggest. Knowing about these differences may make gravitational waves easier to spot. And, of course, actually detecting these differences would be direct evidence of gravitationalturbulence.
“There are potential observational consequences of this discovery,” says Lehner. “LIGO or LISA or some future gravitational wave experiment may be able to detect them.”
But one of the most exciting consequences of this research relates not to gravity, but to ordinary, Earth-boundturbulence. From hurricanes to cream stirred into coffee, from the bumblebee’s impossible flight to the vortices shearing off the end of airplane wings, turbulence is all around us. Yet we don’t fully understand it. It’s considered one of the greatest unsolved problems in classical physics.
This research strengthens the idea that gravity can be treated as a fluid – which also means that fluids can be treated gravitationally.
“We’ve been stuck for over 500 years on achieving a full understanding of turbulence,” says Lehner. “This gravity/fluid correspondence tells us that there is a way to use gravitational tools and gravitational intuition to take a fresh look at turbulence. We may end up as stuck as we are in our standard approach, or we may end up shedding completely new light that helps the field go forward. It’s very exciting.”
Perimeter Institute for Theoretical Physics is an independent, non-profit, scientific research organization working to advance our understanding of physical laws and develop new ideas about the very essence of space, time, matter, and information.
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Solving Sunspot Mysteries
June 6th, 2014
By Nasa.
Multi-wavelength observations of sunspots with the 1.6-meter telescope at Big Bear Solar Observatory (BBSO) in California and aboard NASA’s IRIS spacecraft have produced new and intriguing images of high-speed plasma flows and eruptions extending from the Sun’s surface to the outermost layer of the solar atmosphere, the corona. Operated by New Jersey Institute of Technology (NJIT), BBSO houses the largest ground-based telescope dedicated to solar research.
On June 2, NJIT researchers reported on the acquisition of these images at the 224th meeting of the American Astronomical Society (AAS), held in Boston, Massachusetts. The high-definition video acquired at BBSO provides unique 3D views of a sunspot, revealing rapidly rotating plasma rolls, powerful shocks, and widespread plasma eruptions driven by solar-energy flux and controlled by intense magnetic fields. These leading-edge observations show that sunspots are far more complex and dynamic than previously believed.
Sunspots, first seen by Galileo more than 400 years ago as dark blemishes on the Sun, are still one of the greatest mysteries of astronomy. It has been known for more than a century that sunspots are compact, concentrated magnetic fields and that they appear dark because the magnetism prevents heat from rising to the surface from the superhot interior. But why these magnetic fields become so concentrated and compacted in structures that remain stable for days and sometimes weeks in a very turbulent environment is a mystery.
Sunspots can be the size of Earth or as big as Jupiter. Typical sunspots are nearly round with a very dark and relatively “cold” umbra (7,000 degrees Fahrenheit compared to the 10,000-degree solar surface) surrounded by a less dark and warmer penumbra. However, there are no external forces on the Sun that could hold these giant magnetic structures together. They appear and are organized by their own induced forces. Understanding the processes of such self-organization in the hot turbulent plasma is of fundamental importance for physics and astrophysics.
Investigating sunspots is much more than a matter of curiosity and the desire to increase the fund of basic scientific knowledge. When sunspots that are close to each other have magnetic fields with opposite polarities, they can produce powerful flares and solar storms. On Earth, this can severely damage communications and power infrastructure. Similar but even more intense magnetic phenomena have been detected on other stars, which may be a factor hindering the development of life elsewhere in our Galaxy.
At the AAS meeting, the NJIT researchers presented video chronicling several hours in the life of an isolated sunspot that did not generate solar flares. But the roiling action revealed was a transformative view of sunspots as static-equilibrium structures maintaining a balance between magnetic force and gas pressure.
The telescope at BBSO that made these unparalleled observations possible was completed in 2009 under the leadership of Philip Goode, NJIT distinguished professor of physics and at the time director of the university’s Center for Solar-Terrestrial Research. The telescope is equipped with adaptive optics that include a deformable mirror to compensate for the atmospheric distortion of images in real time. Images are captured with very fast cameras in 15-second “bursts” of 100 images, and then processed using a speckle reconstruction technique to improve sharpness.
The imaging and data-acquisition systems were developed by the BBSO engineering team led by Wenda Cao, NJIT associate professor of physics and the observatory’s associate director. The data recorded is unique in that it comprises a long, uninterrupted series that allows researchers to look at a sunspot’s life cycle and activity with unprecedented spatial resolution. Previously, only short series or snapshots with suchresolution were available.
The sunspot data shared at the AAS meeting was obtained on September 29, 2013. The solar surface, the photosphere, was imaged using a red-light filter in the range of molecular TiO lines, to achieve the best contrast in the sunspot’s umbra. Simultaneously, scanning the hydrogen H-alpha spectral line facilitated imaging at five different wavelengths. The H-alpha data yielded images of plasma flows at various layers in the solar atmosphere, enabling the NJIT researchers to obtain a dynamic 3D view of the sunspot. The BBSO data was compared with UV images of the high and hot atmosphere obtained by NASA’s IRIS satellite for the same region. This joint observing program allows investigation of the origins of solar UV radiation.
The data as presented in the high-definition video shown at the meeting reveals small-scale activity of a generally “quiet” sunspot in unprecedented detail. Remarkably, the organization of small-scale substructures is comparable to that seen at larger scales, indicating the existence of large-scale dynamics which control the formation and stability of sunspots. In particular, the TiO images provide the first detailed view of the darkest regions of sunspots, revealing rapidly rotating convective rolls in the penumbra and similarly rotating relatively bright “umbral dots.” The umbral dots form an evolving pattern clearly linked to the outer penumbra structure. Such evolution provides evidence for large-scale flows that probably play a key role in the self-organization and stability of sunspots.
The most prominent features in the Sun’s chromosphere are periodic pulses — shocks generated by sunspots at intervals of about three minutes. The shocks, which travel into the high solar atmosphere with a speed of about 45,000 miles per hour, are observed by the IRIS spacecraft as UV flashes above the sunspot. The sunspot’s umbra is covered by ubiquitous eruptions — plasma jets that may contribute to the shocks detected.
The most significant UV emissions and violent motion are observed above the area where the penumbra intrudes into the umbra, the so-called “light bridge.” It is likely that this effect is related to anomalies in the sunspot’s magnetic topology, and requires further investigation. Some of the most dramatic events are high-speed plasma jets originating from the penumbra, as well as the apparent chromospheric accretion of dense plasma sheets into the sunspot. The origin of the accretion flows is another puzzle.
Looking ahead, the NJIT researchers plan to use quantitative diagnostics to study plasma and magnetic-field properties through analysis of polarized solar light, and to integrate realistic numerical simulations performed on supercomputer systems into their work. Comparable simulations at the NASA Ames Research Center have revealed a magnetic self-organization process that caused a compact “mini-spot” magnetic structure to form through the interaction of vortex tubes below the visible solar surface.
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Cats found to eat more in thewinter and less in the summer
June 1st, 2014By University School of Veterinary Science.
Researchers from the University’s School of Veterinary Science, in collaboration with colleagues at the Royal Canin Research Centre in France, spent four years monitoring how much cats chose to eat, and found that food intake increased in colder months and decreased during the summer.
Veterinarian and study author, Dr Alex German, said: “Cats, like many humans are more inclined to comforteat when it’s cold outside but, in their case, it’s likely to be due to the extra energy they need to keep warm when out and about.”
The study found that cats ate approximately 15% less food during summer, and the vets have concluded that the extra effort to keep warm in winter and the temptation to rest during hot summer days contributed to the swing in activity levels during the year.
The cats were all inhabitants of a centre in southern France where they were allowed to play and exercise outside all year round. The cats were of mixed breeds, ages and genders. Data on food was compared to the climate in the area using computer modelling to provide information about how the temperature changed over the year.
Seasonal food intake has also been examined in the past on farm animals, such as dairy cows, to establish new ways of increasing milk production, but this is the largest study that has yet taken place with domestic cats.
Dr German said: “People should consider the amount of food their cats need at different times of year as this can be part of helping them to maintain a healthy weight.”
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Mesopotamia far wetter and more fertile 12.000 Years ago
May 29th, 2014
By University of Barcelona.
The study is co-headed by the University of Barcelona and the University of Lleida, together with the Archaeological Museum of Catalonia.
The study has been published in the journal Nature Communications. Researchers Ramon Buxó, archaeologist and director of the Archaeological Museum of Catalonia-Girona, and Mònica Aguilera, UdL researcher who is now working at the Paris Natural History Museum, participated in the study too.
Researchers used crop physiology techniques to analyse archaeobotanical remains. In total, they analysed 367 kernels —for instance, barley and wheat—, and 362 wood samples obtained in eleven archaeological sites from Upper Mesopotamia, which includes present south-eastern Turkey and northern Siria, to the Near East. Studied kernels belong to present crops of wheat and barley species that are similar to the archaeological remains found in the region.
Progressive domestication
Researchers compared the size of kernel remains with present samples to determine the evolution of crop domestication. “The methodology used to date does not reproduce real size; it measures width and long of charred kernels”, explains Josep Lluís Araus, professor from the Department of Plan Biology of UB. “We have reconstructed cereal kernel weight —adds the expert— and seen that it increased for a longer period of time than it was thought, probably during several millenniums”. According to the researcher, the initial selection of kernel was “unconscious”, in other words, first farmers selected the biggest kernels, so size increased progressively.
Wetter and more fertile soils
Sample analysis of carbon and nitrogen isotope compositions —a technique used in crop physiology and improvement— was a key factor to describe the conditions of the area. On one hand, “Carbon isotope composition enables to evaluate water availability for crops. It reached its maximum level 9,000 years ago, and then it decreased progressively until the beginning of our times”, points out Araus. In any case, researchers have not found conclusive evidences about the use of irrigation as a common practice. “This information together with cereal kernel weight allows assessing the productivity of ancient crops”, highlights Josep Lluís Araus.
On the other hand, nitrogen isotope composition provides information about soil’s organic matter and fertility. Juan Pedro Ferrio (Agrotecnio-UdL) affirms that “although they were dryland crops, it can be affirmed that nitrogen was much more available than today: undoubtedly, soils were much more fertile than nowadays”. Moreover, it can be observed a progressive decrease of soil fertility, probably due to over-exploitation or the use of less fertile soils, but also to more extreme climate conditions.
These data enable to describe more precisely agronomic conditions and the evolution of human populations linked to agricultural practices. “The study relates conditions like water availability or soil fertility to crops yield”, states Josep Lluís Araus. Past yields, compared with average calorie needs of one person, enable, for example, to have a rough idea of the crop area needed to feed the population. “This information —adds Araus— can be used to know more precisely the borders of past settlements and the evolution of human communities. The aim is to include all this information in models in order to better understand the past”, concludes the researcher.
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DARPA brain implant for PTSD, brain injuries and other neurological disorders
May 29th, 2014Alton Parrish.
“Deep brain stimulation has been shown to be an effective treatment for a variety of brain diseases, especially those involving movement like Parkinson’s disease,” says Emad Eskandar MD, director of functional neurosurgery at MGH and the project’s principal investigator.
The initiative, called Transdiagnostic Restoration of Affective Networks by System Identification and Function Oriented Real-Modeling and Deep Brain Stimulation (TRANSFORM DBS), involves cross-hospital collaborations along with partners from the Massachusetts Institute of Technology (MIT), and Draper Labs.
“We’re strongly encouraged by the previous data connected with this approach,” says Eskandar. “Our hope is that this project will not only restore quality of life for those affected, both military and civilian, but dramatically change the way we approach the treatment of neuropsychiatric disorders.”
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Mind alteration device makes flies sing and dance
May 26th, 2014By Vienna University of Technology.
In a joint effort with collaboration partners from the Vienna University of Technology and a lab in the USA, the team of Andrew Straw at the IMP developed a special device for the thermogenetic control of flies. This tool, called FlyMAD, enabled the scientists to target light or heat to specific body regions of flies in motion and to analyse the animals‘ brain cells.
Compared to other techniques, FlyMAD allows highly improved temporal resolution. Using the new technology, Straw and his colleagues got new insight into the role of two neuronal cell types in courtship behavior of flies. The results of the study will be published online in Nature Methods on May 25 (doi 10.1038/nmeth.2973).
This composite image shows a laser being aimed at a walking fly using the FlyMAD system.
Credit: Matt Staley and Dan Bath, JFRC, HHMI
The fruit fly Drosophila Melanogaster represents an ideal experimental system to analyse circuit functions of brain cells (neurons). In the past, it was not possible to specifically control the activity of neurons in moving flies. Andrew Straw and his team have now overcome this barrier.
Rapid mind alteration in moving flies
Straw and his co-workers are interested in the mechanisms underlying cell circuits in the fly brain. Straw’s group concentrates on the control of complex behaviors such as courtship. In order to better understand how different neuronal circuits work together, Straw and his team developed FlyMAD (“Fly Mind Altering Device”), an apparatus using a video camera to track the flies‘ motion in a box. FlyMAD allows simultaneous observation of several flies and targeted irradiation of specific body regions of these animals. By combining the sensitive methods of optogenetics and thermogenetics, the researchers were able to specifically alter neural pathways in the fly brain with FlyMAD.
The novel technology of thermogenetics uses genetically modified, temperature-sensitive flies. Upon irradiation with infrared light and the concomitant rise in temperature to 30 degrees Celsius, these animals change certain aspects of their behavior. This does not happen at a control temperature of 24 degrees Celsius. Compared to other commonly used methods, FlyMAD applies a highly improved temporal resolution. Infrared-induced activation or repression of specific neurons and the following change in the animals‘ behavior occur within the fraction of a second.
A male Drosophila raises a wing and ‘sings’ due to neuronal activation of song neurons. FlyMAD enables precisely aiming an infrared laser at a fly in which a warmth-sensitive ion channel was genetically introduced into previously identified neurons.
Image credit: Dan Bath, JFRC, HHMI
The application of visible light to certain genetically engineered flies can also induce alterations of their brain. FlyMAD thus represents an absolute novelty for fly research, as optogenetics has been restricted to mice so far.
New insight into courtship behavior of flies
Straw and his co-workers tested FlyMAD by analyzing already known reactions of genetically modified flies to light and heat. As this proof-of-principle showed that FlyMAD worked reliably – for example by making the flies “moonwalk” – the researchers went on to use their method to tackle new scientific questions.
In a thermogenetic set up, they investigated a certain type of neurons that had been linked to the flies’ courtship song in earlier experiments. Taking advantage of the better temporal resolution of FlyMAD, the scientists were able to characterize the role of two neuronal cell types in the brain in more detail.
They could show that activity of one type of neurons correlated with a persistent state of courtship, whereas the other cell type was important for the action of “singing”. In the experiment this became obvious when males tried to mate with a ball of wax, circled it and started vibrating their wings after stimulation with the laser beam.
FlyMAD allows combination of optogenetics and thermogenetics
In the future, Straw wants to combine the activation of flies both by light and by heat in one experiment – that is feasible with FlyMAD. This would allow the activation or repression of different genetic elements in one fly.
“FlyMAD offers the fantastic opportunity to address many of our questions. We could, for example, analyze how single neurons function in a cascade within the neuronal circuit“, Straw emphasizes the potential of his work. Ultimately, new insight into the function of the fly brain can also be applied to the network of cells in the mammalian brain.
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African fairy circles not created by termites after all
May 21st, 2014
By Alton Parrish.
New study of mysterious bare patches in Namibian grasslands supports theory of self-organisation
Leipzig. For several decades scientists have been trying to come up with an explanation for the formation ofthe enigmatic, vegetation-free circles frequently found in certain African grassland regions. Now researchers have tested different prevailing hypotheses as to their respective plausibility.
For the first time they have carried out a detailed analysis of the spatial distribution of these fairy circles – and discovered a remarkably regular and spatially comprehensive homogenous distribution pattern. This may best be explained by way of reference to local resource-competition for water among plants and vegetation, the team now reports in the scientific journal Ecography.
Aerial view of the mysterious fairy circles of Namibia. The enigmatic, bare patches within the grassland occur in millions at the transition to the Namib Desert. This picture was taken in the Marienfluss Valley, close to one of the study areas for which the scientists have undertaken extensive aerial image analyses.
Photo: Dr. Stephan Getzin/UFZ
The authors of the study have, for the first time ever, investigated the spatial patterns of the fairy circles in detail. Typical for these patterns are the regularly spaced distances in-between circles at small neighbourhood scale while homogeneously spread distribution prevails at large scale level. The scientists conclude from these results to have found strong support for the theory of self-organisation, with the remarkable circle patterns emerging as a result of plant competition for water
Close-up view of a fairy circle. Total absence of vegetation growth within the almost circular area of a typical fairy circle. The sizes of fairy circles may vary, ranging from two to more than twenty metres in diameter. The average diameter recorded here, in the Marienfluss Valley, was approx. six meters.
Photo: Dr. Stephan Getzin/UFZ
It looks like a landscape covered with freckles. Arid grassland regions in certain parts of southwest Africa are covered with barren circular patches. Some of these measure only a few metres, others reach up to twenty (20) metres in diameter; and most of them display pronounced and lush peripheral growth of grass. These so-called fairy circles virtually do extend an open invitation for speculation: What has led to the formation ofthese enigmatic structures?
“Although scientists have been trying to answer this question for decades their mystery remains as yet unresolved”, states Dr. Stephan Getzin from the Helmholtz Centre for Environmental Research (UFZ) in Leipzig – because up to now no one has been able to actually observe, in situ, the genesis of a fairy circle.
There are however several theories, the most popular of which hypothesises that these mysterious patches are the work of termites. The insects allegedly nibble away at the grassroots, thus causing the dieback of vegetation. Other researchers consider hydrocarbons emanating from the depths of the earth being responsible for this phenomenon. Like in a chimney, these gases are presumed to be rising to the surface resulting in the localised loss and disappearance of vegetation.
A third fraction of scientists believes self-regulating grass growth in itself being the cause, under certain circumstances, for this type of spatial patterning since it is remarkable that the occurrence of fairy circles appears to be restricted to particularly arid zones right at the transition from grassland to desert regions. This is where intense localised resource-competition for water exists among existing vegetation. If competition becomes too strong and available soil moisture resources too scarce this could lead to the emergence of bare patches with a lush peripheral grass ring formation.
Together with colleagues from Göttingen (Germany), Italy and Israel, Stephan Getzin has investigated which of these three hypotheses is most likely to be right. “We have adopted an entirely novel approach in this research”, reports this member of the UFZ institute, who by now has been studying fairy circles for more than 15 years.
This study is based on the review and evaluation of aerial images, covering representative regions with fairy circle occurrences throughout northwest Namibia. With the aid of these images scientists have analysed for the first time the exact spatial location and distribution of these barren patches within the surrounding landscape: Are they arranged and positioned merely by chance – just like coins dropped accidentally and now scattered all over the place? Are there signs or distinguishable patterns of clustering in certain locations? Or do these patches perhaps need to maintain a minimum distance to their respective neighbours?
This can hardly be seen and detected with the naked eye. But statistical methodology is available to illustrate the respective distribution patterns, at different levels of scale. According to this methodology fairy circles are distributed surprisingly regular and homogenous, even across large spatial areas. “The occurrence of such patterning in nature is rather unusual” says Stephan Getzin. “There must be particularly strong regulating forces at work“.
However, in his view this rather discredits the generally popular termite theory. In a study published in the scientific journal Science (2013) the sand termite species Psammotermes allocerus was indeed presented as most likely suspect for the creation of the enigmatic barren patches – albeit primarily based on the argument, that the occurrence of this particular species of termites has been common to all fairy circles investigated at the time. No one has so far observed these creatures actually grazing holes into the Namibian grasslands – let alone in such consistent patterns.
Stephan Getzin points out: “There is, up to now, not one single piece of evidence demonstrating that social insects are capable of creating homogenously distributed structures, on such a large scale”. On the contrary: The entire range of studies covering the distribution of ant and termite populations in arid territories predominantly rather attests to the occurrence of irregular, clustered distribution patterns at large scales. And, according to the research team, underground emission of abiotic gases, as well, is unlikely to result in such evenly dispersed and homogeneous spatial distribution.
What remains as probable cause is local resource-competition among plants and vegetation – which incidentally seems quite capable of creating homogeneously scattered circles. Whereas, for example, in a young-growth forest plants will grow and develop at comparatively close range, vegetation will thin out and regress, over the years, in a self-organising process.
Each mature tree, after all, needs sufficient space and nutrition for its development and will therefore be able to survive only at an appropriate distance to its neighbour. A similar process of resource-competition may consequently also be the real cause for a self-organising formation of the mysterious fairy circle patterns.
Using a computer model Stephan Getzin and his colleagues from Israel, who are specialised in this type of processing techniques, have simulated belowground competition for water and the resulting spatial vegetation distribution patterns – and very similar patterns indeed emerged on the screen, akin to the images recorded in Namibia. And in the course of all statistical review and analysis performed, the characteristics of simulated and real fairy circles turned out to be remarkably congruent and close to identical. For the UFZ researchers this represents compelling evidence, that the enigmatic patches may in fact be the result of spatially self-organising grass growth. “We consider this at present being the most convincing explanation“.
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Matter created from light
May 20th, 2014By Alton Parrish.
In just one day over several cups of coffee in a tiny office in Imperial’s Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.
The new research, published in Nature Photonics, shows for the first time how Breit and Wheeler’s theory could be proven in practice. This ‘photon-photon collider’, which would convert light directly into matter using technology that is already available, would be a new type of high-energy physics experiment. This experimentwould recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts, which are the biggest explosions in the universe and one of physics’ greatest unsolved mysteries.
The scientists had been investigating unrelated problems in fusion energy when they realised what they were working on could be applied to the Breit-Wheeler theory. The breakthrough was achieved in collaboration with a fellow theoretical physicist from the Max Planck Institute for Nuclear Physics, who happened to be visiting Imperial.
Demonstrating the Breit-Wheeler theory would provide the final jigsaw piece of a physics puzzle which describes the simplest ways in which light and matter interact (see image in notes to editors). The six other pieces in that puzzle, including Dirac’s 1930 theory on the annihilation of electrons and positrons and Einstein’s 1905 theory on the photoelectric effect, are all associated with Nobel Prize-winning research (see image).
Professor Steve Rose from the Department of Physics at Imperial College London said: “Despite all physicists accepting the theory to be true, when Breit and Wheeler first proposed the theory, they said that they never expected it be shown in the laboratory. Today, nearly 80 years later, we prove them wrong. What was so surprising to us was the discovery of how we can create matter directly from light using the technology that we have today in the UK. As we are theorists we are now talking to others who can use our ideas to undertake this landmark experiment.”
The collider experiment that the scientists have proposed involves two key steps. First, the scientists would use an extremely powerful high-intensity laser to speed up electrons to just below the speed of light. They would then fire these electrons into a slab of gold to create a beam of photons a billion times more energetic than visible light.
The next stage of the experiment involves a tiny gold can called a hohlraum (German for ’empty room’). Scientists would fire a high-energy laser at the inner surface of this gold can, to create a thermal radiation field, generating light similar to the light emitted by stars.
They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can.
Lead researcher Oliver Pike who is currently completing his PhD in plasma physics, said: “Although the theory is conceptually simple, it has been very difficult to verify experimentally. We were able to develop the idea for the collider very quickly, but the experimental design we propose can be carried out with relative ease and with existing technology. Within a few hours of looking for applications of hohlraums outside their traditional role in fusion energy research, we were astonished to find they provided the perfect conditions for creating a photon collider. The race to carry out and complete the experiment is on!”
The research was funded by the Engineering and Physical Sciences Research Council (EPSRC), the John Adams Institute for Accelerator Science, and the Atomic Weapons Establishment (AWE), and was carried out in collaboration with Max-Planck-Institut für Kernphysik.
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As California gets drier, mountains get higher, may trigger earthquakes
May 17th, 2014By University of Berkeley.
Pole showing the approximate altitude of the land surface in 1925, 1955 and 1977 at a site in the San Joaquin Valley southwest of Mendota, Calif., where researchers identified the approximate location of maximum subsidence in the United Sta
Photo Courtesy USGS.
While the seasonal changes in the Central Valley aquifer have not yet been firmly associated with any earthquakes, studies have shown that similar levels of periodic stress, such as that caused by the motions of the moon and sun, increase the number of microquakes on the San Andreas Fault, which runs parallel to the mountain ranges. If these subtle seasonal load changes are capable of influencing the occurrence of microquakes, it is possible that they can sometimes also trigger a larger event, said Roland Bürgmann, UC Berkeley professor of earth and planetary science at UC Berkeley.
“The stress is very small, much less than you need to build up stress on a fault toward an earthquake, but in some circumstances such small stress changes can be the straw that broke the camel’s back; it could just give that extra push to get a fault to fail,” Bürgmann said.
Bürgmann is a coauthor of a report published online this week by the journalNature. The study, based on detailed global positioning satellite (GPS) measurements from California and Nevada between 2007 and 2010, was led by former UC Berkeley postdoctoral fellows Colin Amos, now at Western Washington University, and Pascal Audet, now of the University of Ottawa. The detailed GPS analysis was performed by William C. Hammond and Geoffrey Blewitt of the University of Nevada, Reno.
Draining of Central Valley
Water has been pumped from California’s Central Valley for more than 150 years, reducing what used to be a marsh and extensive lake, Tulare Lake, into fertile agricultural fields that feed the world. In that time, approximately 160 cubic kilometers (40 cubic miles) of water was removed – the capacity of Lake Tahoe – dropping the water table in some areas more than 120 meters (400 feet) and the ground surface 5 meters (16 feet) or more.
The weight of water removed allowed the underlying crust or lithosphere to rise by so-called isostatic rebound, which has raised the Sierra probably as much as half a foot since about 1860, Bürgmann said.
The same rebound happens as a result of the state’s seasonal rains. Torrential winter storms drop water and snow across the state, which eventually flow into Central Valley streams, reservoirs and underground aquifer, pushing down the crust and lowering the Sierra 1-3 millimeters. In the summer, water flow through the delta into the Pacific Ocean, evaporation and ground water pumping for irrigation, which has accelerated in the past few years because of a drought, allows the crust and surrounding mountains to rise again.
Bürgmann said that the flexing of Earth’s crust downward in winter would clamp the San Andreas Fault tighter, lowering the risk of quakes, while in summer the upward flexure would relieve this clamping and perhaps increase the risk.
“The hazard is ever so slightly higher in the summer than in the wintertime,” he said. “This suggests that climate and tectonics interact; that water changes ultimately affect the deeper Earth too.”
High-resolution mapping with continuous GPS
Millimeter-precision measurements of elevation have been possible only in the last few years, with improved continuous GPS networks – part of the National Science Foundation-funded Plate Boundary Observatory, which operates 1,100 stations around the western U.S. – and satellite-based interferometric synthetic aperture radar (InSAR). Synthetic aperture radar is a form of radar in which phase information is used to mapelevation.
Credit: UC Berkeley
These measurements revealed a steady yearly rise of the Sierra of 1-2 millimeters per year, which was initially ascribed to tectonic activity deep underground, even though the rate was unusually high, Bürgmann said. The new study provides an alternative and more reasonable explanation for the rise of the Sierra in historic times.
“The Coast Range is doing the same thing as the Sierra Nevada, which is part of the evidence that this can’t be explained by tectonics,” he said. “Both ranges have uplifted over the last few years and they both exhibit the same seasonal up and down movement in phase. This tells us that something has to be driving the system at a seasonal and long-term sense, and that has to be groundwater recharging and depletion.”
In response to the current drought, about 30 cubic kilometers (7.5 cubic miles) of water were removed from Central Valley aquifers between 2003 and 2010, causing a rise of about 10 millimeters (2/5 inch) in the Sierra over that time.
After the new results were shared with colleagues, Bürgmann said, some geologists suggested that the state could get a better or at least comparable inventory of available water each year by using GPS to measure ground deformation instead of measuring snowpack and reservoir levels.
Other coauthors are Colin B. Amos of Western Washington University in Bellingham, Ingrid A. Johanson of UC Berkeley. Funding for the research came from NSF EarthScope and UC Berkeley’s Miller Institute.
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Teaching robots right from wrong?
May 15th, 2014
By Alton Parrish.
In a project funded by the Office of Naval Research and coordinated under the Multidisciplinary University Research Initiative, scientists will explore the challenges of infusing autonomous robots with a sense for right, wrong, and the consequences of both.
One scenario is a battlefield, he says. A robot medic responsible for helping wounded soldiers is ordered to transport urgently needed medication to a nearby field hospital. En route, it encounters a Marine with a fractured leg. Should the robot abort the mission to assist the injured? Will it?
If the machine stops, a new set of questions arises. The robot assesses the soldier’s physical state and determines that unless it applies traction, internal bleeding in the soldier’s thigh could prove fatal. However, applying traction will cause intense pain. Is the robot morally permitted to cause the soldier pain, even if it’s for the soldier’s well-being?
The ONR-funded project will first isolate essential elements of human moral competence through theoretical and empirical research. Based on the results, the team will develop formal frameworks for modeling human-level moral reasoning that can be verified. Next, it will implement corresponding mechanisms for moral competence in a computational architecture.
“Our lab will develop unique algorithms and computational mechanisms integrated into an existing and proven architecture for autonomous robots,” says Scheutz. “The augmented architecture will be flexible enough to allow for a robot’s dynamic override of planned actions based on moral reasoning.”
Once architecture is established, researchers can begin to evaluate how machines perform in human-robot interaction experiments where robots face various dilemmas, make decisions, and explain their decisions in ways that are acceptable to humans.
Selmer Bringsjord, head of the Cognitive Science Department at RPI, and Naveen Govindarajulu, post-doctoral researcher working with him, are focused on how to engineer ethics into a robot so that moral logic is intrinsic to these artificial beings. Since the scientific community has yet to establish what constitutes morality in humans the challenge for Bringsjord and his team is severe.
In Bringsjord’s approach, all robot decisions would automatically go through at least a preliminary, lightning-quick ethical check using simple logics inspired by today’s most advanced artificially intelligent and question-answering computers. If that check reveals a need for deep, deliberate moral reasoning, such reasoning would be fired inside the robot, using newly invented logics tailor-made for the task.
“We’re talking about robots designed to be autonomous; hence the main purpose of building them in the first place is that you don’t have to tell them what to do,” Bringsjord said. “When an unforeseen situation arises, a capacity for deeper, on-board reasoning must be in place, because no finite rule set created ahead of time by humans can anticipate every possible scenario.”
Bertram Malle, from the Department of Cognitive, Linguistic and Psychological Services at Brown University, will perform some of the human research and human-robot interaction studies. “To design a morally competent robot that interacts with humans we need to first get clear on how moral competence functions in humans,” he said. “There is a fair amount of scientific knowledge available, but there are still many unanswered questions. By answering some of these questions in the project, we can move closer to designing a robot that has moral competence.”
The overall goal of the project, says Scheutz, “is to examine human moral competence and its components. If we can computationally model aspects of moral cognition in machines, we may be able to equip robots with the tools for better navigating real-world dilemmas.”
Besides the experts from Tufts, Brown, and RPI, this team will include consultants from Georgetown University and Yale University in this multi-year effort.
The group brings together extensive research expertise in theoretical models of moral cognition and communication; experimental research on human reasoning; formal modeling of reasoning; design of computational architectures; and implementation in robotic systems.
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Drugs and alcohol played a sacred role in ancient societies
May 15th, 2014
By Alton Parrish.
Despite the fact that the consumption of these substances is as ancient as human society itself, it is only fairly recently that researchers have started to look into the historical and cultural contexts in which mind-altering products were used in Europe. To add to the body of literature about the anthropology of intoxication in prehistoric European societies, Guerra-Doce systematically documented the cultural significance of consuming inebriating substances in these cultures.
Credit: Wikipedia
Because Guerra-Doce mainly found traces of sensory-altering products in tombs and ceremonial places, she believes such substances are strongly linked to ritual usage. They were consumed in order to alter the usual state of consciousness, or even to achieve a trance state. The details of the rituals are still unclear, but the hypothesis is that the substances were either used in the course of mortuary rites, to provide sustenance for the deceased in their journey into the afterlife, or as a kind of tribute to the underworld deities.
She adds that the right to use such substances may have been highly regulated given that they were a means to connect with the spirit world, and therefore played a sacred role among prehistoric European societies.
“Far from being consumed for hedonistic purposes, drug plants and alcoholic drinks had a sacred role among prehistoric societies,” says Guerra-Doce. “It is not surprising that most of the evidence derives from both elite burials and restricted ceremonial sites, suggesting the possibility that the consumption of mind-altering products was socially controlled in prehistoric Europe.”
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Air pollution called one of the largest risks to health worldwide
May 12th, 2014
By Alton Parrish.
According to information released by WHO this week, only 12% of the 1 600 cities in its Urban Air Qualitydatabase comply with Air Quality Guideline levels. And about half of the urban population being monitored is exposed to air pollution that is at least 2.5 times higher than the levels WHO recommends.
Additionally, a WHO report released earlier this year estimates that outdoor air pollution was responsible for the deaths of 3.7 million people under the age of 60 in 2012.
Live Science picked up on this story, reporting that the countries hit hardest by air pollution were low-income and middle-income nations in Southeast Asia and the western Pacific region. ‘In those places, a total of 3.3 million deaths were linked to indoor air pollution and 2.6 million deaths were linked to outdoor air pollution, according to the WHO’.
Meanwhile, across the pond in the USA, air pollution is big in the news this week. New Scientist reports on the Supreme Court ruling that the US Environmental Protection Agency (EPA) can regulate air pollution that drifts across state lines, meaning about 1000 power plants will be forced to reduce their emissions.
The decision won’t please states like Texas and Ohio, where coal-fired power plants are still big business. According to New Scientist, the EPA tried to impose the regulations in 2011, but energy firms and polluting states sued to block the move.
Regarding efforts to tackle air pollution worldwide, Dr Maria Neira of WHO is keen to emphasise that the battle is not lost. ‘We can win the fight against air pollution and reduce the number of people suffering from respiratory and heart disease, as well as lung cancer.’
‘Effective policies and strategies are well understood, but they need to be implemented at sufficient scale. Cities such as Copenhagen and Bogotà, for example, have improved air quality by promoting ‘active transport’ and prioritizing dedicated networks of urban public transport, walking and cycling.’
WHO tells us that other measures include ensuring that houses are energy efficient, that urban development is compact and well served by public transport routes, that street design is appealing and safe for pedestrians and cyclists, and waste is well managed.
There are many components of air pollution, both gaseous and solid. But high concentrations of small and fine particulate pollution is particularly associated with high numbers of deaths from heart disease and stroke, as well as respiratory illnesses and cancers. Measurement of fine particulate matter of 2.5 micrometers or less in diameter (PM2.5) is considered to be the best indicator of the level of health risks from air pollution.
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Exploding head syndrome is real
May 7th, 2014By Alton Parrish.
“It’s a provocative and understudied phenomenon,” said Brian Sharpless, a WSU assistant professor and director of the university psychology clinic, who recently reviewed the scientific literature on the disorder for the journalSleep Medicine Reviews. “I’ve worked with some individuals who have it seven times a night, so it can lead to bad clinical consequences as well.”
People with the syndrome typically perceive abrupt, loud noises—door slams, fireworks, gunshots—as they are going to sleep or waking up. While harmless, the episodes can be frightening.
“Some people start to become anxious when they go into their bedroom or when they try to go to sleep,” said Sharpless. “Daytime sleepiness can be another problem for people.”
Some patients report mild pain. Some hear an explosion in one ear, others in both ears, and yet others within their heads. Some also see what looks like lightning or bright flashes.
Researchers do not know how widespread the problem is, but Sharpless is fielding enough reports of people with the disorder that he thinks it is more widespread than presumed. Just this week, a story on the disorder in Britain’s Daily Mail prompted several people with the syndrome to contact him.
The term “exploding head syndrome” dates to a 1988 article in Lancet but it was described clinically as “snapping of the brain” in 1920. Silas Weir Mitchell, an American physician, wrote in 1876 of two men who experienced explosive-sounding “sensory discharges.”
While the syndrome is recognized in the International Classification of Sleep Disorders, studies using electroencephalogram recordings have only documented the disruptions in periods of relaxed but awake drowsiness.
As with many sleep phenomena, it is largely mysterious.
“In layman’s terms, our best guess is that it occurs when the body doesn’t shut down for sleep in the correct sequence,” said Sharpless. “Instead of shutting down, certain groups of neurons actually get activated and have us perceive the bursts of noise. Behavioral and psychological factors come into play as well, and if you have normally disrupted sleep, the episodes will be more likely to occur.”
Judging from the limited scientific literature and available statistics, Sharpless said the syndrome is more common in women than men. Some medical treatments are available for it, but one possible intervention can be simply reassuring a patient that it is not a dangerous condition.
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Stonehenge: The latest findings show it was built by first Brits
May 7th, 2014By Buckingham University.
Credit: English Heritage
Carbon dating from an archaeological dig by the University of Buckingham shows that the parish of Amesbury, which includes Stonehenge, has been continually occupied for every millennium since 8820BC. The origins of Amesbury have been discovered as a result of carbon dating bones of aurochs (twice the size of bulls), wild boar and red deer following a dig at Vespasian’s Camp, Blick Mead, a mile and a half from Stonehenge last year.
Credit: University of Buckingham
Further startling finds from the dig challenge previous definitions of the Mesolithic and Neolithic cultures. Clearance of land, an activity previously thought to be a part of the ‘farming package’ brought in by Neolithic immigrants from the continent in the 5th millennium BC, appears to have taken place around a substantial area of the spring at Blick Mead between 7500 and 4600BC, a time when Mesolithic culture had been seen as purely nomadic. The persistent use of the site for nearly 3,000 years and the fact that many of the tools found were for domestic purposes rather than hunting ones also points to the fact that people were settling there – previously it was thought that there weren’t any settlers until Neolithic times.
David Jacques, Research Fellow in Archaeology at the University of Buckingham, who led the dig, said: “The site blows the lid off the Neolithic Revolution in a number of ways. It provides evidence for people staying put, clearing land, building, and presumably worshipping, monuments. The area was clearly a hub point for people to come to from many miles away, and in many ways was a forerunner for what later went on at Stonehenge itself. The first monuments at Stonehenge were built by these people. For years people have been asking “why is Stonehenge where it is?”, now at last, we have found the answers.”
“In effect, Blick Mead was the very first Stonehenge Visitor Centre, up and running in the 8th millennium BC. The River Avon would have been the “A” Road – people would have come down on their log boats. They would have had the equivalent of tour guides and there would have been feasting. We have found remains of biggame animals, such as aurochs and red deer, and an enormous amount of burnt flint from their feasting fires. There’s also evidence for a multi-cultural population at the site. Tool types suggest people were coming to it from far to the west of Stonehenge and from the east. Another possible reason why people were attracted to the area was the striking bright pink colouring of the flint, which isn’t that colour anywhere else in the country.”
“The colouring is caused by algae – Hildenbrandia rivularis – and it is due to a combination of dappled light and the unusually warm spring water in the area – 10 to 15 degrees. It’s unique to have people of that time come from so many different far away places. The site and the Stonehenge areas were very well known places to visit for a very long time – the London of the Mesolithic.”
The dig, which is funded by the University of Buckingham, has also unearthed the largest haul of Mesolithic worked flints across the Mesolithic period ever found. In 40-odd days a staggering 31,000 were discovered in a 16 metre square area and more than 2,000 were found in a square metre – the largest concentration of such finds in Europe. 16 m.sq. is the equivalent of the goal post area on a football pitch.
Following the revelations of the University of Buckingham dig, which took place in October last year, David Jacques will be the Programme Director of a new MA in Archaeology, which has been launched by the University of Buckingham. Students can do two 3-day field work activities in the Stonehenge area as part of the course – Stonehenge: A Landscape Through Time. The MA will be part of the University’s London-based courses and will be held at the Society of Antiquaries in central London.
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First U.S. MERS case confirmed by CDC
May 5th, 2014By Alton Parrish.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV) was confirmed today in a traveler to the United States. This virus is relatively new to humans and was first reported in Saudi Arabia in 2012.
On April 24, the patient traveled by plane from Riyadh, Saudi Arabia to London, England then from London to Chicago, Illinois. The patient then took a bus from Chicago to Indiana. On the 27th, the patient began to experience respiratory symptoms, including shortness of breath, coughing, and fever. The patient went to an emergency department in an Indiana hospital on April 28th and was admitted on that same day. The patient is being well cared for and is isolated; the patient is currently in stable condition. Because of the patient’s symptoms and travel history, Indiana public health officials tested for MERS-CoV. The Indiana state public health laboratory and CDC confirmed MERS-CoV infection in the patient this afternoon.
“It is understandable that some may be concerned about this situation, but this first U.S. case of MERS-CoV infection represents a very low risk to the general public,” said Dr. Anne Schuchat, assistant surgeon general and director of CDC’s National Center for Immunizations and Respiratory Diseases. In some countries, the virus has spread from person to person through close contact, such as caring for or living with an infected person. However, there is currently no evidence of sustained spread of MERS-CoV in community settings.
CDC and Indiana health officials are not yet sure how the patient became infected with the virus. Exposure may have occurred in Saudi Arabia, where outbreaks of MERS-CoV infection are occurring. Officials also do not know exactly how many people have had close contact with the patient.
So far, including this U.S. importation, there have been 401 confirmed cases of MERS-CoV infection in 12 countries. To date, all reported cases have originated in six countries in the Arabian Peninsula. Most of these people developed severe acute respiratory illness, with fever, cough, and shortness of breath; 93 people died. Officials do not know where the virus came from or exactly how it spreads. There is no available vaccine or specific treatment recommended for the virus.
“In this interconnected world we live in, we expected MERS-CoV to make its way to the United States,” said Dr. Tom Frieden, Director, Centers for Disease Control and Prevention. “We have been preparing since 2012 for this possibility.”
Federal, state, and local health officials are taking action to minimize the risk of spread of the virus. The Indiana hospital is using full precautions to avoid exposure within the hospital and among healthcare professionals and other people interacting with the patient, as recommended by CDC.
In July 2013, CDC posted checklists and resource lists for healthcare facilities and providers to assist with preparing to implement infection control precautions for MERS-CoV.
As part of the prevention and control measures, officials are reaching out to close contacts to provide guidance about monitoring their health.
While experts do not yet know exactly how this virus is spread, CDC advises Americans to help protect themselves from respiratory illnesses by washing hands often, avoiding close contact with people who are sick, avoid touching their eyes, nose and/or mouth with unwashed hands, and disinfecting frequently touched surfaces.
The largest reported outbreak to date occurred April through May 2013 in eastern Saudi Arabia and involved 23 confirmed cases in four healthcare facilities. At this time, CDC does not recommend anyone change theirtravel plans. The World Health Organization also has not issued Travel Health Warnings for any country related to MERS-CoV. Anyone who develops fever and cough or shortness of breath within 14 day aftertraveling from countries in or near the Arabian Peninsula should see their doctor and let them know where they travelled.
For more information about MERS Co-V, please visit:
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Bug runs at the equivalent of 1300 MPH
April 30th, 2014By Alton Parrish.
Move over, Australian tiger beetle. There’s a new runner in town.
Relative to its size, a Southern California mite runs faster than any other animal, also thrives in temperatures that would kill most other animals.
Although the mite Paratarsotomus macropalpis is no bigger than a sesame seed, it was recently recorded running at up to 322 body lengths per second, a measure of speed that reflects how quickly an animal moves relative to its body size. The previous record-holder, the Australian tiger beetle, tops out at 171 body lengths per second. By comparison, a cheetah running at 60 miles per hour attains only about 16 body lengths per second.
Paratarsotomus macropalpi
Credit: Samuel Rubin (W.M. Keck Science Center, Pitzer College), Dr. J.C. Wright Laboratory (Department Of Biology, Pomona College), The Claremont University Consortium, Claremont, CA.
Extrapolated to the size of a human, the mite’s speed is equivalent to a person running roughly 1300 miles per hour.
The California college student who spent a summer chasing down the remarkable mites says the discovery is exciting not only because it sets a new world record, but also for what it reveals about the physiology of movement and the physical limitations of living structures.
“It’s so cool to discover something that’s faster than anything else, and just to imagine, as a human, going that fast compared to your body length is really amazing,” said Samuel Rubin, a junior and physics major at Pitzer College who led much of the fieldwork to document the mite’s movements. “But beyond that, looking deeper into the physics of how they accomplish these speeds could help inspire revolutionary new designs for things like robots or biomimetic devices.”
Rubin’s advisor, Jonathan Wright, Ph.D., a professor of biology at Pomona College, became interested in the mites while studying the effect of muscle biochemistry on how quickly animals can move their legs. But it wasn’t until Rubin and other students documented the mites’ running speeds in their natural environment that the research team knew they had found a new world record.
Both relative speed and stride frequency increase as animals get smaller, and in theory, muscle physiology should at some point limit how fast a leg can move. “We were looking at the overarching question of whether there is an upper limit to the relative speed or stride frequency that can be achieved,” said Wright. “When the values for mites are compared with data from other animals, they indicate that, if there is an upper limit, we haven’t found it yet.”
The mite is local to Southern California and is often found running along rocks or sidewalks. Although it was first identified in 1916, little is known about its habits or food sources.
The research team used high-speed cameras to record the mites’ sprints in the laboratory and in their natural environment. “It was actually quite difficult to catch them, and when we were filming outside, you had to follow them incredibly quickly as the camera’s field of view is only about 10 centimeters across,” said Rubin.
The research team was also surprised to find the mites running on concrete up to 140 degrees Fahrenheit (60 degrees Celsius), a temperature significantly higher than the upper lethal temperature of most animals. “They’re operating at temperatures that seem to preclude activities of any other animal group. We’ve seen them running where there were no other animals visibly active,” said Wright.
The mites also are adept at stopping and changing directions extremely quickly, attributes the researchers are investigating further for potential insights that may be relevant to bioengineering applications.
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Remarkable genetic diversity seen in ocean microbes
April 26th, 2014
By Alton Parrish.
Image: Carly Sanker/MIT
Sallie Chisholm, the Lee and Geraldine Martin Professor of Environmental Studies in CEE and in MIT’s Department of Biology; former CEE postdoc Nadav Kashtan; and co-authors published a paper on this work in the April 25 issue of Science.
The researchers estimate that the subpopulations diverged at least a few million years ago. The backbone is an older, more slowly evolving component of the genome, while the flexible genes reside in areas of the genome where gene exchange is relatively frequent, facilitating more rapid evolution.
The study also revealed that the relative abundance of the backbone subpopulations changes with the seasons at the study site, near Bermuda, adding strength to the argument that each subpopulation is finely tuned for optimal growth under different conditions.
“The sheer enormity of diversity that must be in the octillion Prochlorococcus cells living in the seas is daunting to consider,” Chisholm says. “It creates a robust and stable population in the face of environmental instability.”
Scientists on an oceanographic research ship lower a rosette of 24 bottles into the ocean to capture samples of wild microbes in their natural habitat.
Photo: Paul Berube/MIT
“The interesting question is, ‘Why does such a diverse set of subpopulations exist?’” Kashtan says. “The huge population size of Prochlorococcus suggests that this remarkable diversity and the way it is organized is not random, but is a masterpiece product of natural selection.”
Chisholm and Kashtan say the evolutionary and ecological distinction among the subpopulations is probably common in other wild, free-living (not attached to particles or other organisms) bacteria species with large populations and highly mixed habitats.
“This is perhaps the most sophisticated and thorough study yet to be published on the fine-scale genetic diversification of an environmental microbial species, and it correctly, I think, predicts that amazingly diverse populations may be maintained over astonishingly long times,” says Ford Doolittle, a member of the biochemistry and molecular biology faculty at Dalhousie University who was not involved in the research. “If microbiologists persist in believing in ‘species,’ they will likely have to drastically revise upward their estimates of how many such things there are. What we will probably be arguing about for a long time is what processes or forces other than selection might be responsible for such stable diversity, and, unless we find such processes, how something so seemingly well mixed as the ocean can offer up so many different tiny selective regimes.”
Scientists on an oceanographic research ship lower a rosette of 24 bottles into the ocean to capture samples of wild microbes in their natural habitat.
Photo: Paul Berube/MIT
“This study may be setting a record for progress made in microbiology by analyzing just three drops of seawater,” says Ramunas Stepanauskas of the Bigelow Laboratory for Ocean Sciences in Boothbay, Maine, who worked on the genomic analysis.
Other co-authors are Sara Roggensack, Sébastien Rodrigue, Jessie Thompson, Steven Biller, Allison Coe, Huiming Ding, Roman Stocker, and Michael Follows of MIT; Pekka Marttinen of the Helsinki Institute for Information Technology; and Rex Malmstrom of the Department of Energy’s Joint Genome Institute.
The work was supported by the National Science Foundation (NSF) Division of Environmental Biology, the NSF Biological Oceanography Section, the NSF Center for Microbial Oceanography Research and Education (C-MORE), the U.S. Department of Energy’s Genomics Science Program, and the Gordon and Betty Moore Foundation Marine Microbiology Initiative.
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Food shortages coming warns to scientist
April 22nd, 2014
By Alton Parrish.
The world is less than 40 years away from a food shortage that will have serious implications for people and governments, according to a top scientist at the U.S. Agency for International Development.
“For the first time in human history, food production will be limited on a global scale by the availability of land, water and energy,” said Dr. Fred Davies, senior science advisor for the agency’s bureau of food security. “Food issues could become as politically destabilizing by 2050 as energy issues are today.”
This is Dr. Fred Davies, US Agency for International Development senior science advisor for the agency’s bureau of food security and a Texas A&M AgriLife Regents Professor of Horticultural Sciences.
Credit: Texas A&M AgriLife Research photo by Kathleen Phillips
Davies, who also is a Texas A&M AgriLife Regents Professor of Horticultural Sciences, addressed the North American Agricultural Journalists meeting in Washington, D.C. on the “monumental challenge of feeding the world.”
He said the world population will increase 30 percent to 9 billion people by mid-century. That would call for a 70 percent increase in food to meet demand.
“But resource limitations will constrain global food systems,” Davies added. “The increases currently projected for crop production from biotechnology, genetics, agronomics and horticulture will not be sufficient to meet food demand.” Davies said the ability to discover ways to keep pace with food demand have been curtailed by cutbacks in spending on research.
“The U.S. agricultural productivity has averaged less than 1.2 percent per year between 1990 and 2007,” he said. “More efficient technologies and crops will need to be developed — and equally important, better ways forapplying these technologies locally for farmers — to address this challenge.” Davies said when new technologies are developed, they often do not reach the small-scale farmer worldwide.
“A greater emphasis is needed in high-value horticultural crops,” he said. “Those create jobs and economic opportunities for rural communities and enable more profitable, intense farming.” Horticultural crops, Davies noted, are 50 percent of the farm-gate value of all crops produced in the U.S.
He also made the connection between the consumption of fruits and vegetables and chronic disease prevention and pointed to research centers in the U.S. that are making links between farmers, biologists and chemists, grocers, health care practitioners and consumers. That connection, he suggested, also will be vital in the push to grow enough food to feed people in coming years.
“Agricultural productivity, food security, food safety, the environment, health, nutrition and obesity — they are all interconnected,” Davies said. One in eight people worldwide, he added, already suffers from chronic undernourishment, and 75 percent of the world’s chronically poor are in the mid-income nations such as China, India, Brazil and the Philippines.
“The perfect storm for horticulture and agriculture is also an opportunity,” Davies said. “Consumer trends such as views on quality, nutrition, production origin and safety impact what foods we consume. Also, urban agriculture favors horticulture.” For example, he said, the fastest growing segment of new farmers in California, are female, non-Anglos who are “intensively growing horticultural crops on small acreages,” he said.
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floating nuclear plants a good idea?
April 18th, 2014By Alton Parrish.
New power plant design could provide enhanced safety, easier siting, and centralized construction
When an earthquake and tsunami struck the Fukushima Daiichi nuclear plant complex in 2011, neither the quake nor the inundation caused the ensuing contamination. Rather, it was the aftereffects — specifically, the lack of cooling for the reactor cores, due to a shutdown of all power at the station — that caused most of the harm.
This illustration shows a possible configuration of a floating offshore nuclear plant, based on design work by Jacopo Buongiorno and others at MIT’s Department of Nuclear Science and Engineering. Like offshore oil drilling platforms, the structure would include living quarters and a helipad for transportation to the site.
Illustration courtesy of Jake Jurewicz/MIT-NSE
A new design for nuclear plants built on floating platforms, modeled after those used for offshore oil drilling, could help avoid such consequences in the future. Such floating plants would be designed to be automatically cooled by the surrounding seawater in a worst-case scenario, which would indefinitely prevent any melting of fuel rods, or escape of radioactive material.
The concept is being presented this week at the Small Modular Reactors Symposium, hosted by the American Society of Mechanical Engineers, by MIT professors Jacopo Buongiorno, Michael Golay, and Neil Todreas, along with others from MIT, the University of Wisconsin, and Chicago Bridge and Iron, a major nuclear plant and offshore platform construction company.
Such plants, Buongiorno explains, could be built in a shipyard, then towed to their destinations five to seven miles offshore, where they would be moored to the seafloor and connected to land by an underwater electric transmission line. The concept takes advantage of two mature technologies: light-water nuclear reactors and offshore oil and gas drilling platforms. Using established designs minimizes technological risks, says Buongiorno, an associate professor of nuclear science and engineering (NSE) at MIT.
Although the concept of a floating nuclear plant is not unique — Russia is in the process of building one now, on a barge moored at the shore — none have been located far enough offshore to be able to ride out a tsunami, Buongiorno says. For this new design, he says, “the biggest selling point is the enhanced safety.”
A floating platform several miles offshore, moored in about 100 meters of water, would be unaffected by the motions of a tsunami; earthquakes would have no direct effect at all. Meanwhile, the biggest issue that faces most nuclear plants under emergency conditions — overheating and potential meltdown, as happened at Fukushima, Chernobyl, and Three Mile Island — would be virtually impossible at sea, Buongiorno says: “It’s very close to the ocean, which is essentially an infinite heat sink, so it’s possible to do cooling passively, with no intervention. The reactor containment itself is essentially underwater.”
Buongiorno lists several other advantages. For one thing, it is increasingly difficult and expensive to find suitable sites for new nuclear plants: They usually need to be next to an ocean, lake, or river to provide cooling water, but shorefront properties are highly desirable. By contrast, sites offshore, but out of sight of land, could be located adjacent to the population centers they would serve. “The ocean is inexpensive real estate,” Buongiorno says.
In addition, at the end of a plant’s lifetime, “decommissioning” could be accomplished by simply towing it away to a central facility, as is done now for the Navy’s carrier and submarine reactors. That would rapidly restore the site to pristine conditions.
This design could also help to address practical construction issues that have tended to make new nuclear plants uneconomical: Shipyard construction allows for better standardization, and the all-steel design eliminates the use of concrete, which Buongiorno says is often responsible for construction delays and cost overruns.
There are no particular limits to the size of such plants, he says: They could be anywhere from small, 50-megawatt plants to 1,000-megawatt plants matching today’s largest facilities. “It’s a flexible concept,” Buongiorno says.
Most operations would be similar to those of onshore plants, and the plant would be designed to meet all regulatory security requirements for terrestrial plants. “Project work has confirmed the feasibility of achieving this goal, including satisfaction of the extra concern of protection against underwater attack,” says Todreas, the KEPCO Professor of Nuclear Science and Engineering and Mechanical Engineering.
Buongiorno sees a market for such plants in Asia, which has a combination of high tsunami risks and a rapidly growing need for new power sources. “It would make a lot of sense for Japan,” he says, as well as places such as Indonesia, Chile, and Africa.
The paper was co-authored by NSE students Angelo Briccetti, Jake Jurewicz, and Vincent Kindfuller; Michael Corradini of the University of Wisconsin; and Daniel Fadel, Ganesh Srinivasan, Ryan Hannink, and Alan Crowle of Chicago Bridge and Iron, based in Canton, Mass.
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Study finds recent wolf-dog hybridization
April 16th, 2014By Alton Parrish.
The study was undertaken as part of Dr. Kopaliani’s work exploring human-wolf conflict in Georgia. “Since the 2000s, the frequency of wolf depredation on cattle has increased in Georgia, and there were several reports of attacks on humans. Wolves were sighted even in densely populated areas,” she explained.
“Reports suggested that, unlike wild wolves, wolf-dog hybrids might lack fear of humans, so we wanted to examine the ancestry of wolves near human settlements to determine if they could be of hybrid origin with free-ranging dogs such as shepherds,” she added.
The research team examined maternally-inherited DNA (mitochondrial DNA) and microsatellite markers to study hybridization rates. Microsatellite markers mutate easily, as they do not have any discernible purpose in the genome, and are highly variable even within a single population. For these reasons, they are often used to study hybridization.
“We expected to identify some individuals with hybrid ancestry, but it was quite surprising that recent hybrid ancestry was found in every tenth wolf and every tenth shepherd dog,” said study co-author Tarkhnishvili.
“Two dogs out of the 60 or so we studied were inferred to be first generation hybrids,” he added.
The study also found that about a third of the dogs sampled shared relatively recent maternal ancestry with local wolves, not with wolves domesticated in the Far East, where most experts believe dogs were first domesticated.
The research team used several alternate methods to confirm their results, and came to the same conclusions with each approach.
The shepherd dogs studied are a local breed used to guard livestock. “Ironically, their sole function is to protect sheep from wolves or thieves,” Kopaliani explained. “The shepherd dogs are free-ranging, largely outside the tight control of their human masters. They guard the herds from wolves, which are common in the areas where they are used, but it appears that they are also consorting with the enemy.”
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