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Sample records for hot spot mobile

  1. Lawrence Livermore National Laboratory hot spot mobile laboratory

    SciTech Connect

    Buddemeier, B

    1999-08-27

    Gross alpha/beta/tritium liquid The Hot Spot Mobile Laboratory is an asset used to analyze samples (some high hazard) from the field. Field laboratories allow the quick turnaround of samples needed to establish weapon condition and hazard assessment for the protection of responders and the public. The Hot Spot Lab is configured to fly anywhere in the world and is staffed by expert scientists and technicians from Lawrence Livermore National Laboratory who perform similar functions in their routine jobs. The Hot Spot Team carries sample control kits to provide responding field teams with the procedures, tools, and equipment for sample collection and field measurements. High-hazard samples brought back from the field are prepared for analysis in HEPA-filtered gloveboxes staffed by technicians from LLNL's Plutonium Facility. The samples are passed on to the Mobile Laboratory which carries a variety of radiological and chemical analytical equipment in portable configuration for use in the field. Equipment and personnel can also deploy special assets to local hospitals or the field for detection of plutonium in a lung or wound. Quick assessment of personnel contamination is essential for time-critical medical intervention. In addition to pulling the trailer, the Hot Spot Truck also stores some of the equipment, consumables, and a PTO generator. The Hot Spot Laboratory has the capability to be self-sufficient for several weeks when deployed to determine Pu uptake.

  2. Are 'hot spots' hot spots?

    NASA Astrophysics Data System (ADS)

    Foulger, Gillian R.

    2012-07-01

    The term 'hot spot' emerged in the 1960s from speculations that Hawaii might have its origins in an unusually hot source region in the mantle. It subsequently became widely used to refer to volcanic regions considered to be anomalous in the then-new plate tectonic paradigm. It carried with it the implication that volcanism (a) is emplaced by a single, spatially restricted, mongenetic melt-delivery system, assumed to be a mantle plume, and (b) that the source is unusually hot. This model has tended to be assumed a priori to be correct. Nevertheless, there are many geological ways of testing it, and a great deal of work has recently been done to do so. Two fundamental problems challenge this work. First is the difficulty of deciding a 'normal' mantle temperature against which to compare estimates. This is usually taken to be the source temperature of mid-ocean ridge basalts (MORBs). However, Earth's surface conduction layer is ˜200 km thick, and such a norm is not appropriate if the lavas under investigation formed deeper than the 40-50 km source depth of MORB. Second, methods for estimating temperature suffer from ambiguity of interpretation with composition and partial melt, controversy regarding how they should be applied, lack of repeatability between studies using the same data, and insufficient precision to detect the 200-300 °C temperature variations postulated. Available methods include multiple seismological and petrological approaches, modelling bathymetry and topography, and measuring heat flow. Investigations have been carried out in many areas postulated to represent either (hot) plume heads or (hotter) tails. These include sections of the mid-ocean spreading ridge postulated to include ridge-centred plumes, the North Atlantic Igneous Province, Iceland, Hawaii, oceanic plateaus, and high-standing continental areas such as the Hoggar swell. Most volcanic regions that may reasonably be considered anomalous in the simple plate-tectonic paradigm have been

  3. The Uses and Impacts of Mobile Computing Technology in Hot Spots Policing.

    PubMed

    Koper, Christopher S; Lum, Cynthia; Hibdon, Julie

    2015-12-01

    Recent technological advances have much potential for improving police performance, but there has been little research testing whether they have made police more effective in reducing crime. To study the uses and crime control impacts of mobile computing technology in the context of geographically focused "hot spots" patrols. An experiment was conducted using 18 crime hot spots in a suburban jurisdiction. Nine of these locations were randomly selected to receive additional patrols over 11 weeks. Researchers studied officers' use of mobile information technology (IT) during the patrols using activity logs and interviews. Nonrandomized subgroup and multivariate analyses were employed to determine if and how the effects of the patrols varied based on these patterns. Officers used mobile computing technology primarily for surveillance and enforcement (e.g., checking automobile license plates and running checks on people during traffic stops and field interviews), and they noted both advantages and disadvantages to its use. Officers did not often use technology for strategic problem-solving and crime prevention. Given sufficient (but modest) dosages, the extra patrols reduced crime at the hot spots, but this effect was smaller in places where officers made greater use of technology. Basic applications of mobile computing may have little if any direct, measurable impact on officers' ability to reduce crime in the field. Greater training and emphasis on strategic uses of IT for problem-solving and crime prevention, and greater attention to its behavioral effects on officers, might enhance its application for crime reduction. © The Author(s) 2016.

  4. The Earth's Hot Spots.

    ERIC Educational Resources Information Center

    Vink, Gregory E.; And Others

    1985-01-01

    Hot spots are isolated areas of geologic activity where volcanic eruptions, earthquakes, and upwelling currents occur far from plate boundaries. These mantle plumes are relatively stable and crustal plates drift over them. The nature and location of hot spots (with particular attention to the Hawaiian Islands and Iceland) are discussed. (DH)

  5. The Earth's Hot Spots.

    ERIC Educational Resources Information Center

    Vink, Gregory E.; And Others

    1985-01-01

    Hot spots are isolated areas of geologic activity where volcanic eruptions, earthquakes, and upwelling currents occur far from plate boundaries. These mantle plumes are relatively stable and crustal plates drift over them. The nature and location of hot spots (with particular attention to the Hawaiian Islands and Iceland) are discussed. (DH)

  6. Solar 'hot spots' are still hot

    NASA Technical Reports Server (NTRS)

    Bai, Taeil

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

  7. Configurable hot spot fixing system

    NASA Astrophysics Data System (ADS)

    Kajiwara, Masanari; Kobayashi, Sachiko; Mashita, Hiromitsu; Aburada, Ryota; Furuta, Nozomu; Kotani, Toshiya

    2014-03-01

    Hot spot fixing (HSF) method has been used to fix many hot spots automatically. However, conventional HSF based on a biasing based modification is difficult to fix many hot spots under a low-k1 lithography condition. In this paper we proposed a new HSF, called configurable hotspot fixing system. The HSF has two major concepts. One is a new function to utilize vacant space around a hot spot by adding new patterns or extending line end edges around the hot spot. The other is to evaluate many candidates at a time generated by the new functions. We confirmed the proposed HSF improves 73% on the number of fixing hot spots and reduces total fixing time by 50% on a device layout equivalent to 28nm-node. The result shows the proposed HSF is effective for layouts under the low-k1 lithography condition.

  8. Hot Spot Cosmic Accelerators

    NASA Astrophysics Data System (ADS)

    2002-11-01

    length of more than 3 million light-years, or no less than one-and-a-half times the distance from the Milky Way to the Andromeda galaxy, this structure is indeed gigantic. The region where the jets collide with the intergalactic medium are known as " hot spots ". Superposing the intensity contours of the radio emission from the southern "hot spot" on a near-infrared J-band (wavelength 1.25 µm) VLT ISAAC image ("b") shows three distinct emitting areas; they are even better visible on the I-band (0.9 µm) FORS1 image ("c"). This emission is obviously associated with the shock front visible on the radio image. This is one of the first times it has been possible to obtain an optical/near-IR image of synchrotron emission from such an intergalactic shock and, thanks to the sensitivity and image sharpness of the VLT, the most detailed view of its kind so far . The central area (with the strongest emission) is where the plasma jet from the galaxy centre hits the intergalactic medium. The light from the two other "knots", some 10 - 15,000 light-years away from the central "hot spot", is also interpreted as synchrotron emission. However, in view of the large distance, the astronomers are convinced that it must be caused by electrons accelerated in secondary processes at those sites . The new images thus confirm that electrons are being continuously accelerated in these "knots" - hence called "cosmic accelerators" - far from the galaxy and the main jets, and in nearly empty space. The exact physical circumstances of this effect are not well known and will be the subject of further investigations. The present VLT-images of the "hot spots" near 3C 445 may not have the same public appeal as some of those beautiful images that have been produced by the same instruments during the past years. But they are not less valuable - their unusual importance is of a different kind, as they now herald the advent of fundamentally new insights into the mysteries of this class of remote and active

  9. Saturn's Hot Spot

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This is the sharpest image of Saturn's temperature emissions taken from the ground; it is a mosaic of 35 individual exposures made at the W.M. Keck I Observatory, Mauna Kea, Hawaii on Feb. 4, 2004.

    The images to create this mosaic were taken with infrared radiation. The mosaic was taken at a wavelength near 17.65 microns and is sensitive to temperatures in Saturn's upper troposphere. The prominent hot spot at the bottom of the image is right at Saturn's south pole. The warming of the southern hemisphere was expected, as Saturn was just past southern summer solstice, but the abrupt changes in temperature with latitude were not expected. The tropospheric temperature increases toward the pole abruptly near 70 degrees latitude from 88 to 89 Kelvin (-301 to -299 degrees Fahrenheit) and then to 91 Kelvin (-296 degrees Fahrenheit) right at the pole.

    Ring particles are not at a uniform temperature everywhere in their orbit around Saturn. The ring particles are orbiting clockwise in this image. Particles are coldest just after having cooled down in Saturn's shadow (lower left). As they orbit Saturn, the particles increase in temperature up to a maximum (lower right) just before passing behind Saturn again in shadow.

    A small section of the ring image is missing because of incomplete mosaic coverage during the observing sequence.

  10. Hot Spot at Yellowstone

    ERIC Educational Resources Information Center

    Dress, Abby

    2005-01-01

    Within this huge national park (over two million acres spread across Wyoming, Montana, and Idaho) are steaming geysers, hot springs, bubbling mudpots, and fumaroles, or steam vents. Drives on the main roads of Yellowstone take tourists through the major hot attractions, which also include Norris Geyser Basin, Upper and Lower Geyser Basin, West…

  11. Hot Spot at Yellowstone

    ERIC Educational Resources Information Center

    Dress, Abby

    2005-01-01

    Within this huge national park (over two million acres spread across Wyoming, Montana, and Idaho) are steaming geysers, hot springs, bubbling mudpots, and fumaroles, or steam vents. Drives on the main roads of Yellowstone take tourists through the major hot attractions, which also include Norris Geyser Basin, Upper and Lower Geyser Basin, West…

  12. Mobile Launch Platform Vehicle Assembly Building Area (SWMU 056) Hot Spot 3 Bioremediation Interim Measures Work Plan, Kennedy Space Center, Florida

    NASA Technical Reports Server (NTRS)

    Whitney L. Morrison; Daprato, Rebecca C.

    2016-01-01

    This Interim Measures Work Plan (IMWP) presents an approach and design for the remediation of chlorinated volatile organic compound (CVOC) groundwater impacts using bioremediation (biostimulation and bioaugmentation) in Hot Spot 3, which is defined by the area where CVOC (trichloroethene [TCE], cis-1,2-dichloroethene [cDCE], and vinyl chloride [VC]) concentrations are greater than 10 times their respective Florida Department of Environmental Protection (FDEP) Natural Attenuation Default Concentration (NADC) [10xNADC] near the western Mobile Launch Platform (MLP) structure. The IM treatment area is the Hot Spot 3 area, which is approximately 0.07 acres and extends from approximately 6 to 22 and 41 to 55 feet below land surface (ft BLS). Within Hot Spot 3, a source zone (SZ; area with TCE concentrations greater than 1% solubility [11,000 micrograms per liter (micrograms/L)]) was delineated and is approximately 0.02 acres and extends from approximately 6 to 16 and 41 to 50 ft BLS.

  13. Computational Prediction of Hot Spot Residues

    PubMed Central

    Morrow, John Kenneth; Zhang, Shuxing

    2013-01-01

    Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues. PMID:22316154

  14. ESA uncovers Geminga's `hot spot'

    NASA Astrophysics Data System (ADS)

    2004-07-01

    16 July 2004 Astronomers using ESA’s X-ray observatory XMM-Newton have detected a small, bright ‘hot spot’ on the surface of the neutron star called Geminga, 500 light-years away. The hot spot is the size of a football field and is caused by the same mechanism producing Geminga’s X-ray tails. This discovery identifies the missing link between the X-ray and gamma-ray emission from Geminga. hi-res Size hi-res: 1284 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot This figure shows the effects of charged particles accelerated in the magnetosphere of Geminga. Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (in red) hit the star’s magnetic poles like in an ‘own goal’. Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degrees hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. An animated version of the entire sequence can be found at: Click here for animated GIF [low resolution, animated GIF, 5536 KB] Click here for AVI [high resolution, AVI with DIVX compression, 19128 KB] hi-res Size hi-res: 371 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (a) Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of

  15. A Strong Hot Spot Theorem

    SciTech Connect

    Bailey, David H.; Misiurewicz, Michal

    2005-12-31

    A real number alpha is said to be b-normal if every m-long string of digits appears in the base-b expansion of alpha with limiting frequency b-m. We prove that alpha is b-normal if and only if it possesses no base-b ''hot spot''. In other words, alpha is b-normal if and only if there is no real number y such that smaller and smaller neighborhoods of y are visited by the successive shifts of the base-b expansion of alpha with larger and larger frequencies, relative to the lengths of these neighborhoods

  16. HotRegion: a database of predicted hot spot clusters

    PubMed Central

    Cukuroglu, Engin; Keskin, Ozlem

    2012-01-01

    Hot spots are energetically important residues at protein interfaces and they are not randomly distributed across the interface but rather clustered. These clustered hot spots form hot regions. Hot regions are important for the stability of protein complexes, as well as providing specificity to binding sites. We propose a database called HotRegion, which provides the hot region information of the interfaces by using predicted hot spot residues, and structural properties of these interface residues such as pair potentials of interface residues, accessible surface area (ASA) and relative ASA values of interface residues of both monomer and complex forms of proteins. Also, the 3D visualization of the interface and interactions among hot spot residues are provided. HotRegion is accessible at http://prism.ccbb.ku.edu.tr/hotregion. PMID:22080558

  17. Not so hot "hot spots" in the oceanic mantle.

    PubMed

    Bonath, E

    1990-10-05

    Excess volcanism and crustal swelling associated with hot spots are generally attributed to thermal plumes upwelling from the mantle. This concept has been tested in the portion of the Mid-Atlantic Ridge between 34 degrees and 45 degrees (Azores hot spot). Peridotite and basalt data indicate that the upper mantle in the hot spot has undergone a high degree of melting relative to the mantle elsewhere in the North Atlantic. However, application of various geothermometers suggests that the temperature of equilibration of peridotites in the mantle was lower, or at least not higher, in the hot spot than elsewhere. The presence of H(2)O-rich metasomatized mantle domains, inferred from peridotite and basalt data, would lower the melting temperature of the hot spot mantle and thereby reconcile its high degree ofmelting with the lack of a mantle temperature anomaly. Thus, some so-called hot spots might be melting anomalies unrelated to abnormally high mantle temperature or thermal plumes.

  18. Observations of IO hot-spots at coastal sites with the combination of a mobile CE- and LP- DOAS

    NASA Astrophysics Data System (ADS)

    Pöhler, D.; Horbanski, M.; Schmitt, S.; Anthofer, M.; Tschritter, J.; Platt, U.

    2012-04-01

    Reactive iodine species are emitted by seaweed in the intertidal zone of coastal sites during low tide. Beside their oxidation to iodine oxide (IO) and reduction of ozone, they act as precursors for particle formation and therefore have a potential impact on climate. A correlation between iodine oxide and particle formation could be observed in several field studies. However, modelling studies suggest that the so far observed mixing ratios of iodine oxide are too low to explain the observed particle formation. This may be caused by the so far applied measurement techniques which either average over a long measurement path of several km (LP-DOAS) or by immobile in-situ techniques (LIF or BB-CEAS) located typically few 10-100m of the intertidal area. Thus both techniques could not observe local "hot-spots", locations with locally elevated IO levels above the background with small spatial extend (e.g. above a source). We present a new developed Cavity Enhanced Differential Optical Absorption Spectroscopy (CE- DOAS) instrument for the direct identification of IO down to 1ppt. This technique gives the possibility to achieve long absorption light paths in a compact setup (<2.0m) and thus apply the DOAS principle to in-situ measurements. The resonator of the cavity is formed by two high reflective mirrors in the spectral window from 430-460nm. To avoid any interference of reactive iodine compounds with tubes, walls or filters, the resonator is open similar to a LP-DOAS setup. A blue LED is used as light source. The total instrument setup is relatively light (25kg) and can easily be located at different locations. Hence it is possible to setup this instrument directly over the macro algae in the intertidal area during low tide to investigate the IO spatial distribution and "hot-spots". As IO concentrations vary strongly due to different meteorological parameters, the CE-DOAS measurements are combined with LP-DOAS in the same area. Thus the combination allows deriving a

  19. Hot Spot Removal System: System description

    SciTech Connect

    1997-09-01

    Hazardous wastes contaminated with radionuclides, chemicals, and explosives exist across the Department of Energy complex and need to be remediated due to environmental concerns. Currently, an opportunity is being developed to dramatically reduce remediation costs and to assist in the acceleration of schedules associated with these wastes by deploying a Hot Spot Removal System. Removing the hot spot from the waste site will remove risk driver(s) and enable another, more cost effective process/option/remedial alternative (i.e., capping) to be applied to the remainder of the site. The Hot Spot Removal System consists of a suite of technologies that will be utilized to locate and remove source terms. Components of the system can also be used in a variety of other cleanup activities. This Hot Spot Removal System Description document presents technologies that were considered for possible inclusion in the Hot Spot Removal System, technologies made available to the Hot Spot Removal System, industrial interest in the Hot Spot Removal System`s subsystems, the schedule required for the Hot Spot Removal System, the evaluation of the relevant technologies, and the recommendations for equipment and technologies as stated in the Plan section.

  20. HotSpot Software Configuration Management Plan

    SciTech Connect

    Walker, H; Homann, S G

    2009-03-12

    This Software Configuration Management Plan (SCMP) describes the software configuration management procedures used to ensure that the HotSpot dispersion model meets the requirements of its user base, which includes: (1) Users of the PC version of HotSpot for consequence assessment, hazard assessment and safety analysis calculations; and (2) Users of the NARAC Web and iClient software tools, which allow users to run HotSpot for consequence assessment modeling These users and sponsors of the HotSpot software and the organizations they represent constitute the intended audience for this document. This plan is intended to meet Critical Recommendations 1 and 3 from the Software Evaluation of HotSpot and DOE Safety Software Toolbox Recommendation for inclusion of HotSpot in the Department of Energy (DOE) Safety Software Toolbox. HotSpot software is maintained for the Department of Energy Office of Emergency Operations by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL). An overview of HotSpot and NARAC are provided.

  1. HotSpot Software Test Plan

    SciTech Connect

    Walker, H; Homann, S G

    2009-03-12

    This Software Test Plan (STP) describes the procedures used to verify and validate that the HotSpot Health Physics Codes meet the requirements of its user base, which includes: (1) Users of the PC version of HotSpot conducting consequence assessment, hazard assessment and safety analysis calculations; and (2) Users of the NARAC Web and iClient software tools, which allow users to run HotSpot for consequence assessment modeling. This plan is intended to meet Critical Recommendation 2 from the Software Evaluation of HotSpot and DOE Safety Software Toolbox Recommendation for inclusion of HotSpot in the Department of Energy (DOE) Safety Software Toolbox. These users and sponsors of the HotSpot software and the organizations they represent constitute the intended audience for this document. HotSpot software is maintained for the Department of Energy Office of Emergency Operations by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL). An overview of HotSpot and NARAC are provided.

  2. A New Hot Spot on Northern Io

    NASA Image and Video Library

    2001-12-10

    In August 2001, NASA Galileo spacecraft has returned imagery of a hot spot on Jupiter moon Io that was the source of a towering plume indicating a sulfur-dioxide concentration that may have been fallout from the plume.

  3. HotSpot Health Physics Codes

    SciTech Connect

    Homann, S. G.

    2013-04-18

    The HotSpot Health Physics Codes were created to provide emergency response personnel and emergency planners with a fast, field-portable set of software tools for evaluating insidents involving redioactive material. The software is also used for safety-analysis of facilities handling nuclear material. HotSpot provides a fast and usually conservative means for estimation the radiation effects associated with the short-term (less than 24 hours) atmospheric release of radioactive materials.

  4. Modeling deflagration waves out of hot spots

    NASA Astrophysics Data System (ADS)

    Partom, Yehuda

    2017-01-01

    It is widely accepted that shock initiation and detonation of heterogeneous explosives comes about by a two-step process known as ignition and growth. In the first step a shock sweeping through an explosive cell (control volume) creates hot spots that become ignition sites. In the second step, deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in the cell depends on the speed of those deflagration waves and on the average distance between neighboring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration waves may depend on both pressure and temperature. It depends on pressure for quasistatic loading near ambient temperature, and on temperature at high temperatures resulting from shock loading. From the simulation we obtain deflagration fronts emanating out of the hot spots. For 8 to 13 GPa shocks, the emanating fronts propagate as deflagration waves to consume the explosive between hot spots. For higher shock levels deflagration waves may interact with the sweeping shock to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds.

  5. Concentrator hot-spot testing, phase 1

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.

    1987-01-01

    Results of a study to determine the hot-spot susceptibility of concentrator cells, to provide a hot-spot qualification test for concentrator modules, and to provide guidelines for reducing hot-spot susceptibility are presented. Hot-spot heating occurs in a photovoltaic module when the short-circuit current of a cell is lower than the string operating current forcing the cell into reverse bias with a concurrent power dissipation. Although the basis for the concentrator module hot-spot qualification test is the test developed for flat-plate modules, issues, such as providing cell illumination, introduce additional complexities into the testing procedure. The same general guidelines apply for protecting concentrator modules from hot-spot stressing as apply to flat-plate modules. Therefore, recommendations are made on the number of bypass diodes required per given number of series cells per module or source circuit. In addition, a new method for determining the cell temperature in the laboratory or in the field is discussed.

  6. Canopy hot-spot as crop identifier

    SciTech Connect

    Gerstl, S.A.W.; Simmer, C.; Powers, B.J.

    1986-05-01

    Illuminating any reflective rough or structured surface by a directional light source results in an angular reflectance distribution that shows a narrow peak in the direction of retro-reflection. This is called the Heiligenschein or hot-spot of vegetation canopies and is caused by mutual shading of leaves. The angular intensity distribution of the hot-spot, its brightness and slope, are therefore indicators of the plant's geometry. We propose the use of hot-spot characteristics as crop identifiers in satellite remote sensing because the canopy hot-spot carries information about plant stand architecture that is more distinctive for different plant species than, for instance, their spectral reflectance characteristics. A simple three-dimensional Monte Carlo/ray tracing model and an analytic two-dimensional model are developed to estimate the angular distribution of the hot-spot as a function of the size of the plant leaves. The results show that the brightness-distribution and slope of the hot-spot change distinctively for different leaf sizes indicating a much more peaked maximum for the smaller leaves.

  7. Rocket engine hot-spot detector

    NASA Astrophysics Data System (ADS)

    Collamore, F. N.

    1985-04-01

    On high performance devices such as rocket engines it is desirable to know if local hot spots or areas of reduced cooling margin exist. The objective of this program is to design, fabricate and test an electronic hot spot detector capable of sensing local hot spot on the exterior circumference of a regeneratively cooled combustion chamber in order to avoid hardware damage. The electronic hot spot sensor consists of an array of 120 thermocouple elements which are bonded in a flexible belt of polyimide film. The design temperature range is from +30 F to +400 F continuously with an intermittent temperature of 500 F maximum. The thermocouple belt consists of 120 equally spaced copper-Constantan thermocouple junctions which is wrapped around the OMS liquid rocket engine combustion chamber, to monitor temperatures of individual cooling channels. Each thermocouple is located over a cooling channel near the injector end of the combustion chamber. The thermocouple array sensor is held in place by a spring loaded clamp band. Analyses show that in the event of a blocked cooling channel the surface temperature of the chamber over the blocked channel will rise from a normal operating temperature of approx. 300 F to approx. 600 F. The hot spot detector will respond quickly to this change with a response time constant less than 0.05 seconds. The hot spot sensor assembly is fabricated with a laminated construction of layers of Kapton film and an outer protective layer of fiberglass reinforced silicone rubber.

  8. Development of hot spot fixer (HSF)

    NASA Astrophysics Data System (ADS)

    Kotani, Toshiya; Kyoh, Suigen; Kobayashi, Sachiko; Inazu, Takatoshi; Ikeuchi, Atsuhiko; Urakawa, Yukihiro; Inoue, Soichi; Morita, Etsuya; Klaver, Simon; Horiuchi, Takumi; Peeters, Johan; Kuramoto, Satoshi

    2006-03-01

    A new design for manufacturability (DfM) scheme with a lithography compliance check (LCC) and hot spot fixing (HSF) flow has been developed to guarantee design compliance for OPC and RET by combining lithography simulator, hot spot detector and layout modification tool. Hot spots highlighted by the LCC flow are removed by the HSF flow following modification rule consists of "Line-Sizing" (LS) and "Space-Sizing (SS)" that are resize value of line-width and space-width for the original pattern. In order to meet layout modification requirements at the pre- and post- tape out (T.O.) stages, the priorities individually set for the modification rules and the design rules, which provides flexibly to achieve the modification scheme desirable at each stage. For handling large data at a fast speed, Layout Analyzer (LA) and Layout Optimizer (LO) engines were combined with the HSF flow. LA is used to reconstruct the original hierarchy structure, clips off small parts of the layout that include hot spots from the original layout and sends those to LO in order to reduce the computational time and resource. LO optimizes the clipped off layout following the prioritized modification- and design-rules. The new DfM scheme was found to be quite effective for hot spot cleaning for 65nm node and beyond, since it was demonstrated that the HSF flow improved the lithography margin for the metal layer of 65nm node full-chip data by reducing number of hot spots to below 0.1% of original within about 12 hours, using 1CPU of commercially available workstation.

  9. Statistical Hot Spot Model for Explosive Detonation

    SciTech Connect

    Nichols, III, A L

    2005-07-14

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a non-local equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  10. Statistical Hot Spot Model for Explosive Detonation

    SciTech Connect

    Nichols III, A L

    2004-05-10

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a nonlocal equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  11. Jumping-droplet electronics hot-spot cooling

    DOE PAGES

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; ...

    2017-03-20

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

  12. Jumping-droplet electronics hot-spot cooling

    NASA Astrophysics Data System (ADS)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

    2017-03-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  13. Mutation hot spots in mammalian mitochondrial DNA.

    PubMed

    Galtier, Nicolas; Enard, David; Radondy, Yoan; Bazin, Eric; Belkhir, Khalid

    2006-02-01

    Animal mitochondrial DNA is characterized by a remarkably high level of within-species homoplasy, that is, phylogenetic incongruence between sites of the molecule. Several investigators have invoked recombination to explain it, challenging the dogma of maternal, clonal mitochondrial inheritance in animals. Alternatively, a high level of homoplasy could be explained by the existence of mutation hot spots. By using an exhaustive mammalian data set, we test the hot spot hypothesis by comparing patterns of site-specific polymorphism and divergence in several groups of closely related species, including hominids. We detect significant co-occurrence of synonymous polymorphisms among closely related species in various mammalian groups, and a correlation between the site-specific levels of variability within humans (on one hand) and between Hominoidea species (on the other hand), indicating that mutation hot spots actually exist in mammalian mitochondrial coding regions. The whole data, however, cannot be explained by a simple mutation hot spots model. Rather, we show that the site-specific mutation rate quickly varies in time, so that the same sites are not hypermutable in distinct lineages. This study provides a plausible mutation model that potentially accounts for the peculiar distribution of mitochondrial sequence variation in mammals without the need for invoking recombination. It also gives hints about the proximal causes of mitochondrial site-specific hypermutability in humans.

  14. How to Find a Planetary Hot Spot

    NASA Image and Video Library

    2010-10-19

    This graph of data from NASA Spitzer Space Telescope shows how astronomers located a hot spot on a distant gas planet named upsilon Andromedae b. Termed an exoplanet, it orbits a star beyond our sun, and whips around very closely to its star.

  15. Hot-spot tectonics on Io

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1985-01-01

    The thesis is that extensional tectonics and low-angle detachment faults probably occur on Io in association with the hot spots. These processes may occur on a much shorter timescale on Ion than on Earth, so that Io could be a natural laboratory for the study of thermotectonics. Furthermore, studies of heat and detachment in crustal extension on Earth and the other terresrial planets (especially Venus and Mars) may provide analogs to processes on Io. The geology of Io is dominated by volcanism and hot spots, most likely the result of tidal heating. Hot spots cover 1 to 2% of Io's surface, radiating at temperatures typically from 200 to 400 K, and occasionally up to 700K. Heat loss from the largest hot spots on Io, such as Loki Patera, is about 300 times the heat loss from Yellowstone, so a tremendous quantity of energy is available for volcanic and tectonic work. Active volcanism on Io results in a resurfacing rate as high as 10 cm per year, yet many structural features are apparent on the surface. Therefore, the tectonics must be highly active.

  16. Two New Hot Spots on Io

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Near-Infrared Mapping Spectrometer (NIMS) on Galileo obtained this image of half of Io's disk in darkness on September 19, 1997. This image, at 5 microns, shows several hot spots on Io, which are volcanic regions of enhanced thermal emission. The area shown is part of the leading hemisphere of Io.

    Two new hot spots are shown and indicated in the image (New, and Shamshu). Neither of these hot spots were seen by NIMS or the Solid State Imaging Experiment, (SSI) prior to this observation, becoming only recently active. Several other previously known hot spots are labelled in the image. Galileo was at a distance of 342,000 km from Io when this observation was made.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  17. The Power Company Hot-Spot

    NASA Astrophysics Data System (ADS)

    Barresi, Joseph F.

    1984-03-01

    Just as your companies screen and monitor the market place to determine demand and the public's perception of product need, the power company is constantly faced with studying and forecasting the potential for load growth within it's franchised areas. This study and it's resultant forecast for growth has placed the power industry in a hot spot.

  18. Pore collapse and hot spots in HMX

    SciTech Connect

    Menikoff, Ralph

    2003-01-01

    The computing power now available has led researchers to reconsider mesoscale simulations as a means to develop a detailed understanding of detonation waves in a heterogeneous explosive. Since chemical reaction rates are sensitive to temperature, hot spots are of critical importance for initiation. In a plastic-bonded explosive, shock desensitization experiments imply that hot spots generated by pore collapse dominate shock initiation. Here, for the collapse of a single pore driven by a shock, the dependence of the temperature distribution on numerical resolution and dissipative mechanism i s investigated. An inert material (with the constibtive properties of HMX) is used to better focus on the mechanics of pore collapse. ' h o important findings resulted from this study. Eust, too low a resolution can significantly enhance the hot-spot mass. Second, at even moderate piston velocities (< 1W s),s hock dissipation alone does not generate sufficient hot-spot mass. ' b oo ther dissipative mechanism investigated are plastic work and viscous heating. In the cases studied, the integrated lempera!xre distribution has a power-law tail with exponent related to a parameter with dimensions of viscosity. For a particular case, the parameter of either dissipative mechanism can be fit to obtain quantitatively the hot-spot mass needed for initiation. But the dissipative mechanisms scale differently with shock strength and pore size. Consequently, to predict initiation behavior over a range of stimuli and as the micro-stmcture properties of a PBX am varied, sufficient numerical resolution and the correct physical dissipative mechanism are essential.

  19. Factors Influencing Phosphorous Cycling in Biogeochemical 'Hot Spots'

    NASA Astrophysics Data System (ADS)

    Saia, S. M.; Walter, M. T.; Buda, A. R.; Carrick, H. J.; Regan, J. M.

    2015-12-01

    Anthropogenic alteration of the phosphorus (P) cycle has led to subsequent soil and water quality issues. For example, P build up in soils due to historic fertilizer application may become biologically available and exacerbate eutrophication and anoxia in nearby water bodies. In the humid Northeastern United States, storm runoff transports P and also stimulates biogeochemical processes, these locations are termed biogeochemical 'hot spots'. Many studies have looked at nitrogen and carbon cycling in biogeochemical hot spots but few have focused on P. We hypothesize the periodic wetting and drying of biogeochemical hot spots promotes a combination of abiotic and biotic processes that influence the mobility of P. To test this hypothesis, we took monthly soil samples (5 cm deep) from May to October in forest, pasture, and cropped land near Ithaca, NY. In-situ measurements taken with each sample included volumetric soil moisture and soil temperature. We also analyzed samples for 'runoff generated' phosphate, nitrate, and sulfate (from 0.01 M CaCl2 extraction), Fe(II), percent organic matter, pH, as well as oxalate extractable and total P, Al, and Fe. We used linear mixed effects models to test how runoff generated phosphate concentrations vary with soil moisture and whether other environmental factors strengthen/weaken this relationship. The knowledge gained from this study will improve our understanding of P cycling in biogeochemical hot spots and can be used to improve the effectiveness of agricultural management practices in the Northeastern United States.

  20. HotSpot Wizard: a web server for identification of hot spots in protein engineering.

    PubMed

    Pavelka, Antonin; Chovancova, Eva; Damborsky, Jiri

    2009-07-01

    HotSpot Wizard is a web server for automatic identification of 'hot spots' for engineering of substrate specificity, activity or enantioselectivity of enzymes and for annotation of protein structures. The web server implements the protein engineering protocol, which targets evolutionarily variable amino acid positions located in the active site or lining the access tunnels. The 'hot spots' for mutagenesis are selected through the integration of structural, functional and evolutionary information obtained from: (i) the databases RCSB PDB, UniProt, PDBSWS, Catalytic Site Atlas and nr NCBI and (ii) the tools CASTp, CAVER, BLAST, CD-HIT, MUSCLE and Rate4Site. The protein structure and e-mail address are the only obligatory inputs for the calculation. In the output, HotSpot Wizard lists annotated residues ordered by estimated mutability. The results of the analysis are mapped on the enzyme structure and visualized in the web browser using Jmol. The HotSpot Wizard server should be useful for protein engineers interested in exploring the structure of their favourite protein and for the design of mutations in site-directed mutagenesis and focused directed evolution experiments. HotSpot Wizard is available at http://loschmidt.chemi.muni.cz/hotspotwizard/.

  1. Hot Spot Manifestation in Eclipsing Dwarf Nova HT Cassiopeiae

    NASA Astrophysics Data System (ADS)

    Bąkowska, K.; Olech, A.

    2014-09-01

    We report the detection of a hot spot in the light curves of the eclipsing dwarf nova HT Cas during its superoutburst in 2010 November. Analysis of the eight reconstructed light curves of the hot spot eclipses showed directly that the brightness of the hot spot was changing significantly during the superoutburst. Thereby, detected hot spot manifestation in HT Cas is the newest observational evidence for the EMT model for dwarf novae.

  2. Discovery of feature-based hot spots using supervised clustering

    NASA Astrophysics Data System (ADS)

    Ding, Wei; Stepinski, Tomasz F.; Parmar, Rachana; Jiang, Dan; Eick, Christoph F.

    2009-07-01

    Feature-based hot spots are localized regions where the attributes of objects attain high values. There is considerable interest in automatic identification of feature-based hot spots. This paper approaches the problem of finding feature-based hot spots from a data mining perspective, and describes a method that relies on supervised clustering to produce a list of hot spot regions. Supervised clustering uses a fitness function rewarding isolation of the hot spots to optimally subdivide the dataset. The clusters in the optimal division are ranked using the interestingness of clusters that encapsulate their utility for being hot spots. Hot spots are associated with the top ranked clusters. The effectiveness of supervised clustering as a hot spot identification method is evaluated for four conceptually different clustering algorithms using a dataset describing the spatial distribution of ground ice on Mars. Clustering solutions are visualized by specially developed raster approximations. Further assessment of the ability of different algorithms to yield hot spots is performed using raster approximations. Density-based clustering algorithm is found to be the most effective for hot spot identification. The results of the hot spot discovery by supervised clustering are comparable to those obtained using the G* statistic, but the new method offers a high degree of automation, making it an ideal tool for mining large datasets for the existence of potential hot spots.

  3. Hot spot conditions during cavitation in water

    SciTech Connect

    Didenko, Y.T.; McNamara, W.B. III; Suslick, K.S.

    1999-06-23

    Liquids irradiated with high-intensity ultrasound undergo acoustic cavitation--the formation, growth, and implosive collapse of bubbles. The energy stored during the growth of the bubble in the rarefaction phase of the acoustic field is released when the bubble violently collapses in the compression phase of the acoustic field, as acoustic noise, shock waves, chemical reactions, and the emission of light (sonoluminescence, SL). This violent collapse is predicted to generate a hot spot of thousands of Kelvin within the bubble, but, to date, there have been only a limited number of experimental measurements of the temperature of this hot spot. Although the SL of water has been studied for more than 50 years, the effective hot spot temperature during aqueous cavitation remains unresolved. Given the importance of aqueous cavitation (sonography and bioeffects of ultrasound, sonochemical remediation of aqueous pollutants, synthetic applications of sonochemistry, etc.), the authors decided to apply previous spectroscopic analysis of SL of nonaqueous liquids to aqueous solutions doped with small amounts of hydrocarbons. The authors have collected and analyzed excited-state C{sub 2} NBSL (multi-bubble sonoluminescence, light emission from the clouds of cavitating bubbles) spectra from mixtures of organic liquids in water at 20 kHz and find an effective emission temperature of 4,300 {+-} 200 K.

  4. Characterizing hot spots throughout the catchment

    NASA Astrophysics Data System (ADS)

    Welti, N.; Lockington, D.; Jakeman, T.; Hunt, R.

    2012-04-01

    Few catchments in the world are left truly undisturbed. Rather, they are under anthropogenic stress for a variety of reasons ranging from climate forcing to meeting the basic water allocation needs of the population. Reduction in the number of inundation areas has significantly decreased the nutrient and organic matter retention capacity along the river corridor, with major consequences for the both the riverine and coastal ecosystems. Cumulative stress may build up to a "tipping point" which can cause a change or set of changes which could occur non-linearly. In order to mitigate the environmental stress on these ecosystems, management plans are created to balance the needs of the dependent populations and those of ecology. While these catchment-wide plans aim to improve the ecological function of aquatic areas over the large scale, this sledge-hammer approach ignores the inherent heterogeneity in the catchment. Societal (and policy) decisions involve more than abiotic quantification of water storage and flow. A more encompassing ecohydrological view facilitates a more rounded policy framework that has flexibility to accommodate multiple social drivers, and one that can accommodate an "ecosystem improvement" rather than single species improvement. Not every spot in the landscape is equally valuable for specific societal values. Areas of high activity may provide the resilience capacity necessary to prevent catastrophic changes. In times of ecological instability, ecosystem resilience is of paramount importance in maintaining essential ecosystem services. Hot spots of biogeochemical cycling will occur where unique situations arise, such as areas of surface and groundwater interaction, creating spots of localized, high activity. In order to understand the systems' potential to support various habitat niches in the large scale, the identification of specific hot spots or hot moments is necessary. A basal understanding of the concurrent biogeochemical cycles enables

  5. Hot spots become cold spots: coevolution in variable temperature environments.

    PubMed

    Duncan, A B; Dusi, E; Jacob, F; Ramsayer, J; Hochberg, M E; Kaltz, O

    2017-01-01

    Antagonistic coevolution between hosts and parasites is a key process in the genesis and maintenance of biological diversity. Whereas coevolutionary dynamics show distinct patterns under favourable environmental conditions, the effects of more realistic, variable conditions are largely unknown. We investigated the impact of a fluctuating environment on antagonistic coevolution in experimental microcosms of Pseudomonas fluorescens SBW25 and lytic phage SBWΦ2. High-frequency temperature fluctuations caused no deviations from typical coevolutionary arms race dynamics. However, coevolution was stalled during periods of high temperature under intermediate- and low-frequency fluctuations, generating temporary coevolutionary cold spots. Temperature variation affected population density, providing evidence that eco-evolutionary feedbacks act through variable bacteria-phage encounter rates. Our study shows that environmental fluctuations can drive antagonistic species interactions into and out of coevolutionary cold and hot spots. Whether coevolution persists or stalls depends on the frequency of change and the environmental optima of both interacting players. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  6. Photovoltaic module hot spot durability design and test methods

    NASA Technical Reports Server (NTRS)

    Arnett, J. C.; Gonzalez, C. C.

    1981-01-01

    As part of the Jet Propulsion Laboratory's Low-Cost Solar Array Project, the susceptibility of fat-plate modules to hot-spot problems is investigated. Hot-spot problems arise in modules when the cells become back-biased and operate in the negative-voltage quadrant, as a result of short-circuit current mismatch, cell cracking or shadowing. The details of a qualification test for determining the capability of modules of surviving field hot-spot problems and typical results of this test are presented. In addition, recommended circuit-design techniques for improving the module and array reliability with respect to hot-spot problems are presented.

  7. Rec-Mediated Recombinational Hot Spot Activity in Bacteriophage Lambda II. a Mutation Which Causes Hot Spot Activity

    PubMed Central

    Lam, Stephen T.; Stahl, Mary M.; McMilin, Kenneth D.; Stahl, Franklin W.

    1974-01-01

    Crosses have been performed which identify phage mutants (chi) which cause recombinational hot spot activity in λ. The hot spot activity is found in crosses of red- gam- chi- strains in rec+ hosts; in the crosses reported here, both the chi- mutations and the hot spot are located near the right end of the chromosome. The hot spot occurs in standard crosses as well as under conditions which block DNA synthesis, and is dependent on a functional host recB gene.—The chi mutation is shown to be dominant, but the tests do not show whether chi is a gene or a site. PMID:4415485

  8. Multiscale Simulation of Hot Spot Ignition

    NASA Astrophysics Data System (ADS)

    Fried, Laurence; Najjar, Fady; Howard, W. Michael; Manaa, M. Riad; Bastea, Sorin

    2011-06-01

    High explosive shock sensitivity is controlled by a combination of mechanical response, thermal properties, and chemical properties. How these properties interplay in realistic condensed energetic materials is not well understood. In this paper, we use a multiscale approach to achieve a realistic simulation of hot spot (void) ignition in a single crystal of the explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The smallest length scale (<10 nm) of the multiscale model was treated quantum mechanically. We have conducted multiple simulations of the decomposition of the explosive TATB using density functional tight binding molecular dynamics (DFTB-MD). Nanoscale continuum simulations were performed of void ignition using the ALE3D hydrodynamic/thermal/chemical code. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Variation in Ammonia Abundances in Hot Spots on Jupiter

    NASA Astrophysics Data System (ADS)

    Bjoraker, G. L.; De Pater, I.; Wong, M. H.; Adamkovics, M.

    2015-12-01

    We used NIRSPEC on the Keck telescope in 2014 to spectrally resolve line profiles of CH3D, NH3, PH3, and H2O in 5-micron Hot Spots on Jupiter. The profile of the CH3D lines is very broad in both NEB and SEB Hot Spots due to collisions with up to 8 bars of H2, where unit optical depth occurs due to collision-induced H2 opacity. The extreme width of these CH3D features implies that Hot Spots do not have significant cloud opacity for P > 2 bars. We retrieved NH3, PH3, and gaseous H2O inside a Hot Spot at 8.8°N in the NEB and also in an SEB Hot Spot at 17°S. Both Hot Spots have similar radiances, indicating that both regions have very thin upper-level clouds. They both have a strong depletion in H2O for P< 4 bars, suggesting that subsidence is responsible for the depletion of volatiles in Hot Spots. The NEB Hot Spot is depleted in NH3 with respect to adjacent latitudes. Interestingly, the SEB Hot Spot does not have a different NH3 abundance than neighboring regions. The SEB, including the Hot Spot, exhibits strong NH3 absorption in the 2 to 4-bar region. The SEB went through a "fade" or whitening in 2010, and a subsequent "revival" or darkening between 2010 and 2014, implying a cycle of condensation and sublimation of NH3 ice. This cycle may play a role in the differences we observed between the NEB and SEB Hot Spots. The dynamical origin of SEB Hot Spots is much less studied than that of NEB Hot Spots, so our observations of NH3 humidity may provide a key piece of the puzzle. We plan to acquire 5-micron spectra simultaneously with spatially-resolved microwave observations, such as with the Juno Microwave Radiometer or the Very Large Array. Microwave opacity is dominated by gaseous NH3 rather than cloud opacity. We predict that SEB Hot Spots where the 5-micron spectrum shows strong NH3 absorption (like those we observed in 2014) would not stand out in microwave data, breaking the 1:1 correspondence seen between microwave and 5-micron intensity by Sault et al. (2004

  10. Chromosomal context dependence of a eukaryotic recombinational hot spot.

    PubMed Central

    Ponticelli, A S; Smith, G R

    1992-01-01

    The single base-pair mutation M26 in the ade6 gene of the fission yeast Schizosaccharomyces pombe creates a hot spot for meiotic homologous recombination. When DNA fragments containing M26 and up to 3.0 kilobases of surrounding DNA were moved to the ura4 gene or to a multicopy plasmid, M26 had no detectable hot spot activity. Our results indicate that nucleotide sequences at least 1 kilobase away from M26 are required for M26 hot spot activity and suggest that, as for transcriptional promoters, a second site or proper chromatin structure is required for activation of this eukaryotic recombinational hot spot. We discuss the implications of these results for studies of other meiotic recombinational hot spots and for gene targeting. PMID:1729693

  11. The crime prevention value of hot spots policing.

    PubMed

    Braga, Anthony A

    2006-08-01

    This paper reviews the available research evidence on the effectiveness of hot spots policing programs in reducing crime and disorder. The research identified five randomized controlled experiments and four non-equivalent control group quasi-experiments evaluating the effects of hot spots policing interventions on crime. Seven of nine selected evaluations reported noteworthy crime and disorder reductions. Meta-analyses of the randomized experiments revealed statistically significant mean effect sizes favoring hot spots policing interventions in reducing citizen calls for service in treatment places relative to control places. When immediate spatial displacement was measured, it was very limited and unintended crime prevention benefits were associated with the hot spots policing programs. The results of this review suggest that hot spots policing is an effective crime prevention strategy.

  12. KFC Server: interactive forecasting of protein interaction hot spots

    PubMed Central

    Darnell, Steven J.; LeGault, Laura; Mitchell, Julie C.

    2008-01-01

    The KFC Server is a web-based implementation of the KFC (Knowledge-based FADE and Contacts) model—a machine learning approach for the prediction of binding hot spots, or the subset of residues that account for most of a protein interface's; binding free energy. The server facilitates the automated analysis of a user submitted protein–protein or protein–DNA interface and the visualization of its hot spot predictions. For each residue in the interface, the KFC Server characterizes its local structural environment, compares that environment to the environments of experimentally determined hot spots and predicts if the interface residue is a hot spot. After the computational analysis, the user can visualize the results using an interactive job viewer able to quickly highlight predicted hot spots and surrounding structural features within the protein structure. The KFC Server is accessible at http://kfc.mitchell-lab.org. PMID:18539611

  13. KFC Server: interactive forecasting of protein interaction hot spots.

    PubMed

    Darnell, Steven J; LeGault, Laura; Mitchell, Julie C

    2008-07-01

    The KFC Server is a web-based implementation of the KFC (Knowledge-based FADE and Contacts) model-a machine learning approach for the prediction of binding hot spots, or the subset of residues that account for most of a protein interface's; binding free energy. The server facilitates the automated analysis of a user submitted protein-protein or protein-DNA interface and the visualization of its hot spot predictions. For each residue in the interface, the KFC Server characterizes its local structural environment, compares that environment to the environments of experimentally determined hot spots and predicts if the interface residue is a hot spot. After the computational analysis, the user can visualize the results using an interactive job viewer able to quickly highlight predicted hot spots and surrounding structural features within the protein structure. The KFC Server is accessible at http://kfc.mitchell-lab.org.

  14. Diverse fragment clustering and water exclusion identify protein hot spots.

    PubMed

    Kulp, John L; Kulp, John L; Pompliano, David L; Guarnieri, Frank

    2011-07-20

    Simulated annealing of chemical potential located the highest affinity positions of eight organic probes and water on eight static structures of hen egg white lysozyme (HEWL) in various conformational states. In all HELW conformations, a diverse set of organic probes clustered in the known binding site (hot spot). Fragment clusters at other locations were excluded by tightly-bound waters so that only the hot-spot cluster remained in each case. The location of the hot spot was correctly predicted irrespective of the protein conformation and without accounting for protein flexibility during the simulations. Any one of the static structures could have been used to locate the hot spot. A site on a protein where a diversity of organic probes is calculated to cluster, but where water specifically does not bind, identifies a potential small-molecule binding site or protein-protein interaction hot spot.

  15. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    NASA Technical Reports Server (NTRS)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  16. Hot-spot initiation of heterogeneous explosives

    SciTech Connect

    Kipp, M.E.; Nonziato, J.W.; Setchell, R.E.; Walsh, E.K.

    1981-01-01

    It is generally accepted that the shock initiation of heterogeneous explosives begins with the formation of hot spots in the vicinity of microstructural defects such as voids, grain boundaries, and phase boundaries where there can be significant localized deformation as a result of material viscosity, plastic work, and intergranular friction. This phenomenon is described in the context of a recently developed theory of chemically reacting, multiphase mixtures. In particular, we consider a granular explosive with an energetic binder (e.g. PBX-9404) and represent it as a three-phase, saturated mixture consisting of the granular reactant, the binder phase, and the product gases. Under dynamic loading, viscous dissipation results in high temperatures in the binder phase which subsequently thermally explodes to form product gases. Decomposition of the granular reactant is achieved by laminar grain burning. This model has been incorporated into a 1-D Lagrangian finite-difference code (WONDY) and the evolution of compressive shock and acceleration (ramp) waves have been calculated for PBX-9404. The calculated wave growth at the front, as well as the reaction-induced pressure wave behind the wave, are shown to be in good agreement with experimental observations.

  17. Hot-spot heating in central-station arrays

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.

    1983-01-01

    Hot spot tests performed on the Sacramento Municipal Utility District (SMUD) verificaton array show that current imbalance occurs, resulting in significant hot spot heating. One cause of current imbalance is differences in the average shunt resistances of parallel cell strings due to cell shunt resistance variations. In depth hot spot tests are performed on the verification array with bypass diodes. The tests had several objectives: (1) a comparison of hot spot temperatures achieved under field conditions with those obtained with the present laboratory hot spot test using similar modules; (2) an assessment of current imbalance versus cross tie frequency; and (3) an assessment of different shadow patterns and shadow densities. Instrumented modules are used to vary the number of cross ties and to measure the test-cell current and back-bias voltage. The widths, lengths, and densities of the shadows are varied to maximize the back bias voltage at maximum power current. An infrared camera is used to indicate the existence of hot spots and estimate temperature increases in conjunction with thermocouples. The results of these hot spot tests indicate a sensitivity of back bias heating to the shadow size (amount of cell coverage) and density.

  18. Hot spot-ridge crest convergence in the northeast Pacific

    SciTech Connect

    Karsten, J.L.; Delaney, J.R. )

    1989-01-10

    Evolution of the Juan de Fuca Ridge during the past 7 m.y. has been reconstructed taking into account both the propagating rift history and migration of the spreading center in the 'absolute' (fixed hot spot) reference frame. Northwestward migration of the spreading center (at a rate of 30 km/m.y.) has resulted in progressive encroachment of the ridge axis on the Cobb Hot Spot and westward jumping of the central third of the ridge axis more recently than 0.5 Ma. Seamounts in the Cobb-Eickelberg chain are predicted to display systematic variations in morphology and petrology, and a reduction in the age contrast between the edifice and underlying crust, as a result of the ridge axis approach. Relative seamount volumes also indicate that magmatic output of the hot spot varied during this interval, with a reduction in activity between 2.5 and 4.5 Ma, compared with relatively more robust activity before and after this period. Spatial relationships determined in this reconstruction allow hypotheses relating hot spot activity and rift propagation to be evaluated. In most cases, rift propagation has been directed away from the hot spot during the time period considered. Individual propagators show some reduction in propagation rate as separation between the propagating rift tip and hot spot increases, but cross comparison of multiple propagators does not uniformly display the same relationship. No obvious correlation exists between propagation rate and increasing proximity of the hot spot to the ridge axis or increasing hot spot output. Taken together, these observations do not offer compelling support for the concept of hot spot driven rift propagation. However, short-term reversals in propagation direction at the Cobb Offset coincide with activity of the Heckle melting anomaly, suggesting that local propagation effects may be related to excess magma supply at the ridge axis.

  19. Identification of and Remedial Approaches to Hot Spots

    DTIC Science & Technology

    2004-03-01

    New York – Coney Island , NY – Sea Bright, NJ (3 hot spots) • U.S. Army Engineer District, Philadelphia – Ocean City, NJ • U.S. Army Engineer... Island , NY. Coney Island , the westernmost barrier island on Long Island had its first beach nourishment in 1922-23. The latest U.S. Army Corps of...Figure 1. Location of beach-fill project hot spots discussed in paper Figure 2. Coney Island , NY hot spot location 5 ERDC/CHL CHETN-II-47 March

  20. On-chip Hot Spot Remediation with Miniaturized Thermoelectric Coolers

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, Avram; Wang, Peng

    2009-08-01

    The rapid emergence of nanoelectronics, with the consequent rise in transistor density and switching speed, has led to a steep increase in chip heat flux and growing concern over the emergence of on-chip "hot spots" in microprocessors, along with such high flux regions in power electronic chips and LED's. Miniaturized thermoelectric coolers (μ-TEC's) are a most promising cooling technique for the remediation of such hot spots. This paper presents a comprehensive review of recent advances in novel applications of superlattice, mini-contact, and silicon-based miniaturized thermoelectric coolers in reducing the severity of on-chip hot spots.

  1. Phenomenological local field enhancement factor distributions around electromagnetic hot spots

    NASA Astrophysics Data System (ADS)

    Le Ru, E. C.; Etchegoin, P. G.

    2009-05-01

    We propose a general phenomenological description of the enhancement factor distribution for surface-enhanced Raman scattering (SERS) and other related phenomena exploiting large local field enhancements at hot spots. This description extends naturally the particular case of a single (fixed) hot spot, and it is expected to be "universal" for many classes of common SERS substrates containing a collection of electromagnetic hot spots with varying geometrical parameters. We further justify it from calculations with generalized Mie theory. The description studied here provides a useful starting point for a qualitative (and semiquantitative) understanding of experimental data and, in particular, the analysis of the statistics of single-molecule SERS events.

  2. Hot spots of soil respiration in an Asian tropical rainforest

    NASA Astrophysics Data System (ADS)

    Ohashi, Mizue; Kume, Tomonori; Yamane, Seiki; Suzuki, Masakazu

    2007-04-01

    Little is known about the variability in carbon dioxide (CO2) emissions from soil (soil respiration) in tropical rainforests. We studied temporal and spatial fluctuations of soil respiration in an intact Asian tropical rainforest. The values of soil respiration were distributed lognormally with mean and median values of 5.32 and 4.65 μmol m-2 s-1, respectively. Soil respiration varied little over time though highly in space. CO2 hot spots (>10 μmol m-2 s-1) were found with extremely high values (15-25 μmol m-2 s-1). Each CO2 hot spot occurred sporadically at different times and locations. It is hypothesized that animal activities are responsible for the hot spots. The impact of CO2 hot spots on total soil respiration was 10%, which is comparable to the estimation of net C balance in tropical rainforests.

  3. Drilling Into the Track of the Yellowstone Hot Spot

    NASA Astrophysics Data System (ADS)

    Shervais, John W.; Evans, James P.; Schmitt, Douglas R.; Christiansen, Eric H.; Prokopenko, Alexander

    2014-03-01

    The Yellowstone supervolcano erupted roughly 640,000 years ago, covering much of North America in a thick coat of ash. Material ejected from the volcano devastated the surrounding area, and particles injected into the atmosphere changed the Earth's climate. Over the past 18 million years the Yellowstone hot spot has powered a series of similar eruptions. In southern Idaho, the 640-kilometer-long Snake River Plain traces the path of the Yellowstone hot spot over this period.

  4. On the burn topology of hot-spot-initiated reactions

    SciTech Connect

    Hill, Larry G; Zimmermann, Bjorn; Nichols, Albert L

    2009-01-01

    We determine the reaction progress function for an ideal hot spot model problem. The considered problem has an exact analytic solution that can derived from a reduction of Nichols statistical hot spot model. We perform numerical calculations to verify the analytic solution and to illustrate the error realized in real, finite systems. We show how the baseline problem, which does not distinguish between the reactant and product densities, can be scaled to handle general cases for which the two densities differ.

  5. Modelling propagation of deflagration waves out of hot spots

    NASA Astrophysics Data System (ADS)

    Partom, Yehuda

    2015-06-01

    It is widely accepted that shock initiation and detonation of heterogeneous explosives come about by a two-step process known as ignition and growth. In the first step a shock sweeping an explosive cell (control volume) creates hot spots that become ignition sites. In the second step deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in a cell depends on the speed of those deflagration waves and on the average distance between neighbouring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration wave depends on both pressure and temperature, where pressure dependence is dominant at low shock level, and temperature dependence is dominant at a higher shock level. From the simulation we obtain deflagration (or burn) fronts emanating out of the hot spots. For intermediate shock levels the deflagration waves consume the explosive between hot spots. For higher shock levels the deflagration waves strengthen to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds and show how they depend on reaction rate and on other material parameters.

  6. A measurement concept for hot-spot BRDFs from space

    NASA Technical Reports Server (NTRS)

    Gerstl, S.A.W.

    1996-01-01

    Several concepts for canopy hot-spot measurements from space have been investigated. The most promising involves active illumination and bistatic detection that would allow hot-spot angular distribution (BRDF) measurements from space in a search-light mode. The concept includes a pointable illumination source, such as a laser operating at an atmospheric window wavelength, coupled with a number of high spatial-resolution detectors that are clustered around the illumination source in space, receiving photons nearly coaxial with the reto-reflection direction. Microwave control and command among the satellite cluster would allow orienting the direction of the laser beam as well as the focusing detectors simultaneously so that the coupled system can function like a search light with almost unlimited pointing capabilities. The concept is called the Hot-Spot Search-Light (HSSL) satellite. A nominal satellite altitude of 600 km will allow hot-spot BRDF measurements out to about 18 degrees phase angle. The distributed are taking radiometric measurements of the intensity wings of the hot-spot angular distribution without the need for complex imaging detectors. The system can be operated at night for increased signal-to-noise ratio. This way the hot-spot angular signatures can be quantified and parameterized in sufficient detail to extract the biophysical information content of plant architectures.

  7. Hot-spot qualification testing of concentrator modules

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.; Sugimura, R. S.; Ross, R. G., Jr.

    1987-01-01

    Results of a study to determine the hot-spot susceptibility of concentrator cells, to provide a hot-spot qualification test for concentrator modules, and to provide guidelines for reducing hot-spot susceptibility are presented. Hot-spot heating occurs in a photovoltaic module when the short-circuit current of a cell is lower than the string operating current, forcing the cell into reverse bias with a concurrent power dissipation. Although the basis for the concentrator-module hot-spot qualification test is the test developed for flat-plate modules, issues such as providing cell illumination introduce additional complexities into the testing procedure. The results indicate that the same general guidelines apply to protecting concentrator modules from hot-spot stressing as apply to flat-plate modules, and recommendations are made on the number of bypass diodes required per given number of series cells per module or source circuit. A method for determining the cell temperature in the laboratory or in the field is discussed.

  8. A measurement concept for hot-spot BRDFs from space

    SciTech Connect

    Gerstl, S.A.W.

    1996-09-01

    Several concepts for canopy hot-spot measurements from space have been investigated. The most promising involves active illumination and bistatic detection that would allow hot-spot angular distribution (BRDF) measurements from space in a search-light mode. The concept includes a pointable illumination source, such as a laser operating at an atmospheric window wavelength, coupled with a number of high spatial-resolution detectors that are clustered around the illumination source in space, receiving photons nearly coaxial with the reto-reflection direction. Microwave control and command among the satellite cluster would allow orienting the direction of the laser beam as well as the focusing detectors simultaneously so that the coupled system can function like a search light with almost unlimited pointing capabilities. The concept is called the Hot-Spot Search-Light (HSSL) satellite. A nominal satellite altitude of 600 km will allow hot-spot BRDF measurements out to about 18 degrees phase angle. The distributed are taking radiometric measurements of the intensity wings of the hot-spot angular distribution without the need for complex imaging detectors. The system can be operated at night for increased signal-to-noise ratio. This way the hot-spot angular signatures can be quantified and parameterized in sufficient detail to extract the biophysical information content of plant architectures.

  9. Identifying Recombination Hot Spots in the HIV-1 Genome

    PubMed Central

    Smyth, Redmond P.; Schlub, Timothy E.; Grimm, Andrew J.; Waugh, Caryll; Ellenberg, Paula; Chopra, Abha; Mallal, Simon; Cromer, Deborah

    2014-01-01

    ABSTRACT HIV-1 infection is characterized by the rapid generation of genetic diversity that facilitates viral escape from immune selection and antiretroviral therapy. Despite recombination's crucial role in viral diversity and evolution, little is known about the genomic factors that influence recombination between highly similar genomes. In this study, we use a minimally modified full-length HIV-1 genome and high-throughput sequence analysis to study recombination in gag and pol in T cells. We find that recombination is favored at a number of recombination hot spots, where recombination occurs six times more frequently than at corresponding cold spots. Interestingly, these hot spots occur near important features of the HIV-1 genome but do not occur at sites immediately around protease inhibitor or reverse transcriptase inhibitor drug resistance mutations. We show that the recombination hot and cold spots are consistent across five blood donors and are independent of coreceptor-mediated entry. Finally, we check common experimental confounders and find that these are not driving the location of recombination hot spots. This is the first study to identify the location of recombination hot spots between two similar viral genomes with great statistical power and under conditions that closely reflect natural recombination events among HIV-1 quasispecies. IMPORTANCE The ability of HIV-1 to evade the immune system and antiretroviral therapy depends on genetic diversity within the viral quasispecies. Retroviral recombination is an important mechanism that helps to generate and maintain this genetic diversity, but little is known about how recombination rates vary within the HIV-1 genome. We measured recombination rates in gag and pol and identified recombination hot and cold spots, demonstrating that recombination is not random but depends on the underlying gene sequence. The strength and location of these recombination hot and cold spots can be used to improve models of

  10. ``Hot spots'' growth on single nanowire controlled by electric charge

    NASA Astrophysics Data System (ADS)

    Xi, Shaobo; Liu, Xuehua; He, Ting; Tian, Lei; Wang, Wenhui; Sun, Rui; He, Weina; Zhang, Xuetong; Zhang, Jinping; Ni, Weihai; Zhou, Xiaochun

    2016-06-01

    ``Hot spots'' - a kind of highly active site, which are usually composed of some unique units, such as defects, interfaces, catalyst particles or special structures - can determine the performance of nanomaterials. In this paper, we study a model system, i.e. ``hot spots'' on a single Ag nanowire in the galvanic replacement reaction (GRR), by dark-field microscopy. The research reveals that electric charge can be released by the formation reaction of AgCl, and consequently the electrochemical potential on Ag nanowire drops. The electric charge could induce the reduction of Ag+ to form the ``hot spots'' on the nanowire during the GRR. The appearance probability of ``hot spots'' is almost even along the Ag nanowire, while it is slightly lower near the two ends. The spatial distance between adjacent ``hot spots'' is also controlled by the charge, and obeys a model based on Boltzmann distribution. In addition, the distance distribution here has an advantage in electron transfer and energy saving. Therefore, it's necessary to consider the functions of electric charge during the synthesis or application of nanomaterials.``Hot spots'' - a kind of highly active site, which are usually composed of some unique units, such as defects, interfaces, catalyst particles or special structures - can determine the performance of nanomaterials. In this paper, we study a model system, i.e. ``hot spots'' on a single Ag nanowire in the galvanic replacement reaction (GRR), by dark-field microscopy. The research reveals that electric charge can be released by the formation reaction of AgCl, and consequently the electrochemical potential on Ag nanowire drops. The electric charge could induce the reduction of Ag+ to form the ``hot spots'' on the nanowire during the GRR. The appearance probability of ``hot spots'' is almost even along the Ag nanowire, while it is slightly lower near the two ends. The spatial distance between adjacent ``hot spots'' is also controlled by the charge, and obeys a

  11. Process window aware layout optimization using hot spot fixing system

    NASA Astrophysics Data System (ADS)

    Kobayashi, Sachiko; Kyoh, Suigen; Kotani, Toshiya; Inoue, Soichi

    2007-03-01

    The feasibility of Hot Spot Fixing (HSF) system in DfM flow is studied and reported. Hot spot fixing using process simulation is indispensable under low-k1 lithography process for logic devices with advanced design rule (DR). Hot spot such as pinching, bridging, line-end shortening will occur, mainly depending on local pattern context. Proper calibration of DR, mask data preparation (MDP), resolution enhancement technique (RET) and optical proximity effect correction (OPC) will reduce potential hot spots. However, pattern layout variety is so enormous that, even with most careful calibration of every process, unexpected potential hot spots are occasionally left in the design layout 1-2. OPC optimization is useful for maximizing common process margin, but it cannot expand individual pattern's process margin without modification of design layout. So, at an early design stage, hot spot extraction using lithography compliance check (LCC) and manual modification of design at hot spots will be a simple and useful method. The problem is that, it is difficult to determine how to modify layout in order to be consistent with DR, MDP/OPC rule. For proper layout modification, intimate knowledge of the entire process would be necessary, and moreover, the modification work often tends to be iterative, and thus time-consuming. Therefore, using our automated HSF system in the cell design stage and also the chip design stage is helpful for fixing design layout while avoiding fatal hot spot occurrence, with enough process margin and also with short turnaround time (TAT) 3-4. The basic system flow in the developed system is as follows; LCC extracts potential hot spots, and the hot spots are categorized by lithography error mode, grade, and surrounding context. And then, hot spot modification instructor, taking the surrounding situation into consideration, generates modification guide for every hot spot. Design data is automatically modified according to the instruction at every hot

  12. SpotOn: High Accuracy Identification of Protein-Protein Interface Hot-Spots.

    PubMed

    Moreira, Irina S; Koukos, Panagiotis I; Melo, Rita; Almeida, Jose G; Preto, Antonio J; Schaarschmidt, Joerg; Trellet, Mikael; Gümüş, Zeynep H; Costa, Joaquim; Bonvin, Alexandre M J J

    2017-08-14

    We present SpotOn, a web server to identify and classify interfacial residues as Hot-Spots (HS) and Null-Spots (NS). SpotON implements a robust algorithm with a demonstrated accuracy of 0.95 and sensitivity of 0.98 on an independent test set. The predictor was developed using an ensemble machine learning approach with up-sampling of the minor class. It was trained on 53 complexes using various features, based on both protein 3D structure and sequence. The SpotOn web interface is freely available at: http://milou.science.uu.nl/services/SPOTON/ .

  13. Hot Spot Detection System Using Landsat 8/OLI Data

    NASA Astrophysics Data System (ADS)

    Kato, S.; Nakamura, R.; Oda, A.; Iijima, A.; Kouyama, T.; Iwata, T.

    2015-12-01

    We developed a simple algorithm and a Web-based visualizing system to detect hot spots using Landsat 8 OLI multispectral data as one of the applications of the real-time processing of Landsat 8 data. An empirical equation and radiometric and reflective thresholds were derived to detect hot spots using the OLI data at band 5 (0.865 μm) and band 7 (2.200 μm) based on the increase in spectral radiance at shortwave infrared (SWIR) region due to the emission from objects with high surface temperature. We surveyed typical patterns of surface spectra using the ASTER spectral library to delineate a threshold to distinguish hot spots from background surfaces. To adjust the empirical coefficients of our detection algorithm, we visually inspected the detected hot spots using 6593 Landsat 8 scenes, which cover eastern part of East Asia, taken from January 1, 2014 to December 31, 2014, displayed on a dedicated Web GIS system. Eventually we determined threshold equations which can theoretically detect hot spots at temperatures above 230 °C over isothermal pixels and hot spots as small as 1 m2 at temperatures of 1000 °C as the lowest temperature and the smallest subpixel coverage, respectively, for daytime scenes. The algorithm detected hot spots including wildfires, volcanos, open burnings and factories. 30-m spatial resolution of Landsat 8 enabled to detect wild fires and open burnings accompanied by clearer shapes of fire front lines than MODIS and VIIRS fire products. Although the 16-day revisit cycle of Landsat 8 is too long to effectively find unexpected wildfire or outbreak of eruption, the revisit cycle is enough to monitor temporally stable heat sources, such as continually erupting volcanos and factories. False detection was found over building rooftops, which have relatively smooth surfaces at longer wavelengths, when specular reflection occurred at the satellite overpass.

  14. Biodiversity hot spot on a hot spot: novel extremophile diversity in Hawaiian fumaroles

    PubMed Central

    Wall, Kate; Cornell, Jennifer; Bizzoco, Richard W; Kelley, Scott T

    2015-01-01

    Fumaroles (steam vents) are the most common, yet least understood, microbial habitat in terrestrial geothermal settings. Long believed too extreme for life, recent advances in sample collection and DNA extraction methods have found that fumarole deposits and subsurface waters harbor a considerable diversity of viable microbes. In this study, we applied culture-independent molecular methods to explore fumarole deposit microbial assemblages in 15 different fumaroles in four geographic locations on the Big Island of Hawai'i. Just over half of the vents yielded sufficient high-quality DNA for the construction of 16S ribosomal RNA gene sequence clone libraries. The bacterial clone libraries contained sequences belonging to 11 recognized bacterial divisions and seven other division-level phylogenetic groups. Archaeal sequences were less numerous, but similarly diverse. The taxonomic composition among fumarole deposits was highly heterogeneous. Phylogenetic analysis found cloned fumarole sequences were related to microbes identified from a broad array of globally distributed ecotypes, including hot springs, terrestrial soils, and industrial waste sites. Our results suggest that fumarole deposits function as an “extremophile collector” and may be a hot spot of novel extremophile biodiversity. PMID:25565172

  15. Hot SPOT Generation in Energetic Materials by Applying Weak Energies

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Wei; You, Sizhu; Suslick, Kenneth S.; Dlott, Dana D.

    2013-06-01

    Hot spot generation in energetic materials is an important process to initiate the exothermic chemical reaction, but the details of the fundamental science behind this process is still less-known. Although the response of energetic materials to low velocity impact have been heavily studied with high speed imaging, the response to the IR and acoustic is still not known. A high-speed thermal imaging microscopy apparatus was constructed to observe hot spot generation by weak energies (˜30 THz optical frequency or 20 kHz acoustic frequency), to develop the fundamental science needed to understand energy concentration mechanisms leading to hot spot generation. Inhomogeneous crystals with defects and polymer binders were used in the experiments, with weak energies it is possible to detect the hot spot generation without destruction and deflagration-to-detonation transitions. We have successfully recorded the hot spot grown in the 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) crystal and polymer-bonded sugar simulant by applying Far-IR radiation (˜30 THz) and acoustic sonication (20 kHz) respectively, and proceeded preliminary analysis to investigate the mechanism.

  16. Thermal Infrared Hot Spot and Dependence on Canopy Geometry

    NASA Technical Reports Server (NTRS)

    Smith, James A.; Ballard, Jerrell R., Jr.; Smith, David E. (Technical Monitor)

    2001-01-01

    We perform theoretical calculations of the canopy thermal infrared (TIR) hot spot using a first principles 3-D model described earlier. Various theoretical canopies of varying leaf size and for differing canopy height are used to illustrate the magnitude of the TIR effect. Our results are similar to predicted behavior in the reflective hot spot as a function of canopy geometry and comparable to TIR measurements from the literature and our own simple ground experiments. We apply the MODTRAN atmospheric code to estimate the at-sensor variation in brightness temperature with view direction in the solar principal plane. For simple homogeneous canopies, we predict canopy thermal infrared hot spot variations of 2 degrees C at the surface with respect to nadir viewing. Dependence on leaf size is weak as long as the ratio of leaf size to canopy height is maintained. However, the angular width of the hot spot increases as the ratio of leaf diameter to canopy height increases. Atmospheric effects minimize but do not eliminate the TIR hot spot at satellite altitudes.

  17. Integrating sustainable hunting in biodiversity protection in Central Africa: hot spots, weak spots, and strong spots.

    PubMed

    Fa, John E; Olivero, Jesús; Farfán, Miguel Ángel; Márquez, Ana Luz; Vargas, Juan Mario; Real, Raimundo; Nasi, Robert

    2014-01-01

    Wild animals are a primary source of protein (bushmeat) for people living in or near tropical forests. Ideally, the effect of bushmeat harvests should be monitored closely by making regular estimates of offtake rate and size of stock available for exploitation. However, in practice, this is possible in very few situations because it requires both of these aspects to be readily measurable, and even in the best case, entails very considerable time and effort. As alternative, in this study, we use high-resolution, environmental favorability models for terrestrial mammals (N = 165) in Central Africa to map areas of high species richness (hot spots) and hunting susceptibility. Favorability models distinguish localities with environmental conditions that favor the species' existence from those with detrimental characteristics for its presence. We develop an index for assessing Potential Hunting Sustainability (PHS) of each species based on their ecological characteristics (population density, habitat breadth, rarity and vulnerability), weighted according to restrictive and permissive assumptions of how species' characteristics are combined. Species are classified into five main hunting sustainability classes using fuzzy logic. Using the accumulated favorability values of all species, and their PHS values, we finally identify weak spots, defined as high diversity regions of especial hunting vulnerability for wildlife, as well as strong spots, defined as high diversity areas of high hunting sustainability potential. Our study uses relatively simple models that employ easily obtainable data of a species' ecological characteristics to assess the impacts of hunting in tropical regions. It provides information for management by charting the geography of where species are more or less likely to be at risk of extinction from hunting.

  18. Integrating Sustainable Hunting in Biodiversity Protection in Central Africa: Hot Spots, Weak Spots, and Strong Spots

    PubMed Central

    Fa, John E.; Olivero, Jesús; Farfán, Miguel Ángel; Márquez, Ana Luz; Vargas, Juan Mario; Real, Raimundo; Nasi, Robert

    2014-01-01

    Wild animals are a primary source of protein (bushmeat) for people living in or near tropical forests. Ideally, the effect of bushmeat harvests should be monitored closely by making regular estimates of offtake rate and size of stock available for exploitation. However, in practice, this is possible in very few situations because it requires both of these aspects to be readily measurable, and even in the best case, entails very considerable time and effort. As alternative, in this study, we use high-resolution, environmental favorability models for terrestrial mammals (N = 165) in Central Africa to map areas of high species richness (hot spots) and hunting susceptibility. Favorability models distinguish localities with environmental conditions that favor the species' existence from those with detrimental characteristics for its presence. We develop an index for assessing Potential Hunting Sustainability (PHS) of each species based on their ecological characteristics (population density, habitat breadth, rarity and vulnerability), weighted according to restrictive and permissive assumptions of how species' characteristics are combined. Species are classified into five main hunting sustainability classes using fuzzy logic. Using the accumulated favorability values of all species, and their PHS values, we finally identify weak spots, defined as high diversity regions of especial hunting vulnerability for wildlife, as well as strong spots, defined as high diversity areas of high hunting sustainability potential. Our study uses relatively simple models that employ easily obtainable data of a species' ecological characteristics to assess the impacts of hunting in tropical regions. It provides information for management by charting the geography of where species are more or less likely to be at risk of extinction from hunting. PMID:25372705

  19. Coulomb explosion of the hot spot of micropinches

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.; Oreshkin, E. V.

    2017-01-01

    It has been shown that the generation of hard X-ray radiation, electron beam, and high energy ions that have been detected in experiments on compressing pinches can be related to the Coulomb explosion of a micropinch hot spot, which is formed due to the outflow of the material. In the outflow process, the plasma temperature in the hot spot increases and conditions appear for the transition of electrons to the regime of continuous acceleration. The exit of runaway electrons from the hot spot region leads to the creation of a positive bulk charge, then to a Coulomb explosion. Conditions under which electrons pass to the continuous acceleration regime have been determined and estimates of the ion kinetic energy upon a Coulomb explosion have been obtained.

  20. Topolgy Agnostic Hot-Spot Avoidance with InfiniBand

    SciTech Connect

    Vishnu, Abhinav; Koop, Matthew J.; Moody, Adam; Mamidala, Amith; Narravula, Sundeep; Panda, Dhabaleswar K.

    2009-03-01

    InfiniBand has become a very popular interconnect, due to its advanced features and open standard. Large scale InfiniBand clusters are becoming very popular, as reflected by the TOP 500 supercomputer rankings. However, even with popular topologies like constant bi-section bandwidth Fat Tree, hot-spots may occur with InfiniBand, due to inappropriate configuration of network paths, presence of other jobs in the network and un-availability of adaptive routing. In this paper, we present a hot-spot avoidance layer (HSAL) for InfiniBand, which provides hot-spot avoidance using path bandwidth estimation and multi-pathing using LMC mechanism, without taking the network topology into account. We propose an adaptive striping policy with batch based striping and sorting approach, for efficient utilization of disjoint network paths. Integration of HSAL with MPI, the de facto programming model of clusters, shows promising results with collective communication primitives and MPI applications.

  1. Kilauea volcano: the degassing of a hot spot

    SciTech Connect

    Gerlach, T.M.

    1986-03-01

    Hot spots such as Kilauea volcano can degas by a one-stage eruptive process or a two-stage process involving eruptive and noneruptive degassing. One stage degassing occurs during sustained summit eruptions and causes a direct environmental impact. Although generally less efficient than the one-stage degassing process, two stage degassing can cause 1 to 2 orders of magnitude greater impact in just a few hours during flank eruptions. Hot spot volcanos with resupplied crustal magma chambers may be capable of maintaining an equivalent impact from CO/sub 2/ and S outgassing during both eruptive and noneruptive periods. On average, a hot spot volcano such as Kilauea is a minor polluter compared to man.

  2. Effect of a hot spot on the strain response of an acoustically-loaded flat plate

    SciTech Connect

    Koval, L.R.; Jong, C.P.

    1989-01-01

    Previous studies of the acoustic fatigue of heated plates have treated uniformly-heated plates. The current study examines the effect of a 'hot spot' on the acoustic fatigue of a simply-supported flat plate. The hot spot is provided by a concentration of hot gas and is 'applied' to the plate through a convection boundary condition on the upper surface of the plate. For simplicity, the hot spot is assumed to be rectangular with its sides parallel to the sides of the plate. The size of the hot spot, the location of the hot spot, and the temperature of the hot spot were all varied to see their effects. 18 references.

  3. Mammalian recombination hot spots: properties, control and evolution

    PubMed Central

    Paigen, Kenneth; Petkov, Petko

    2015-01-01

    Recombination, together with mutation, generates the raw material of evolution, is essential for reproduction and lies at the heart of all genetic analysis. Recent advances in our ability to construct genome-scale, high-resolution recombination maps and new molecular techniques for analysing recombination products have substantially furthered our understanding of this important biological phenomenon in humans and mice: from describing the properties of recombination hot spots in male and female meiosis to the recombination landscape along chromosomes. This progress has been accompanied by the identification of trans-acting systems that regulate the location and relative activity of individual hot spots. PMID:20168297

  4. Plasmonic electromagnetic hot spots temporally addressed by photoinduced molecular displacement.

    SciTech Connect

    Juan, M. L.; Plain, J.; Bachelot, R.; Vial, A.; Royer, P.; Gray, S. K.; Montgomery, J. M.; Wiederrecht, G. P.; Univ. de Technologie de Troyes

    2009-04-23

    We report the observation of temporally varying electromagnetic hot spots in plasmonic nanostructures. Changes in the field amplitude, position, and spatial features are induced by embedding plasmonic silver nanorods in the photoresponsive azo-polymer. This polymer undergoes cis?trans isomerization and wormlike transport within resonant optical fields, producing a time-varying local dielectric environment that alters the locations where electromagnetic hot spots are produced. Finite-difference time-domain and Monte Carlo simulations that model the induced field and corresponding material response are presented to aid in the interpretation of the experimental results. Evidence for propagating plasmons induced at the ends of the rods is also presented.

  5. Io hot spots - Infrared photometry of satellite occultations

    NASA Technical Reports Server (NTRS)

    Goguen, J. D.; Matson, D. L.; Sinton, W. M.; Howell, R. R.; Dyck, H. M.

    1988-01-01

    Io's active hot spots, which are presently mapped on the basis of IR photometry of this moon's occultation by other Gallilean satellites, are obtained with greatest spatial resolution near the sub-earth point. A model is developed for the occultation lightcurves, and its fitting to the data defines the apparent path of the occulting satellite relative to Io; the mean error in apparent relative position of occulting satellites is of the order of 178 km. A heretofore unknown, 20-km diameter hot spot is noted on Io's leading hemisphere.

  6. Antiferromagnetism and hot spots in CeIn3

    NASA Astrophysics Data System (ADS)

    Gor'Kov, L. P.; Grigoriev, P. D.

    2006-02-01

    Enormous mass enhancement at “hot spots” on the Fermi surface (FS) of CeIn3 has been reported at a strong magnetic field near its antiferromagnetic (AFM) quantum critical point [T. Ebihara , Phys. Rev. Lett. 93, 246401 (2004)] and ascribed to anomalous spin fluctuations at these spots. The hot spots lie at the positions on FS where in nonmagnetic LaIn3 the narrow necks are protruded. In paramagnetic phase, CeIn3 has similar spectrum. We show that in the presence of AFM ordering its FS undergoes a topological change at the onset of AFM order that truncates the necks at the hot spots for one of the branches. The applied field leads to the logarithmic divergence of the dHvA effective mass when the electron trajectory passes near or through the neck positions. This effect explains the observed dHvA mass enhancement at the hot spots and leads to interesting predictions concerning the spin dependence of the effective electron mass. The (T,B) -phase diagram of CeIn3 , constructed in terms of the Landau functional, is in agreement with experiment.

  7. Hot Spot Phase Relations in the Tissint Meteorite

    NASA Astrophysics Data System (ADS)

    Boonsue, S.; Spray, J. G.; Chennaoui Aoudjehane, H.

    2014-09-01

    The restriction of certain shock-induced polymorphs to melt pockets within Tissint suggests formation via hot-spot generation (focused shock). Quenching of the melt generated CAS + Sti + Maj-Prp assemblage at the interface between clast and melt matrix.

  8. Correlated wounded hot spots in proton-proton interactions

    NASA Astrophysics Data System (ADS)

    Albacete, Javier L.; Petersen, Hannah; Soto-Ontoso, Alba

    2017-06-01

    We investigate the effect of nontrivial spatial correlations between proton constituents, considered in this work to be gluonic hot spots, on the initial conditions of proton-proton collisions from ISR to Large Hadron Collider energies, i.e., √{s }=52.6 , 7000, and 13 000 GeV. The inclusion of these correlations is motivated by their fundamental role in the description of a recently observed new feature of p p scattering at √{s }=7 TeV, the hollowness effect. Our analysis relies on a Monte Carlo Glauber approach including fluctuations in the hot spot positions and their entropy deposition in the transverse plane. We explore both the energy dependence and the effect of spatial correlations on the number of wounded hot spots, their spatial distribution, and the eccentricities, ɛn, of the initial state geometry of the collision. In minimum bias collisions we find that the inclusion of short-range repulsive correlations between the hot spots reduces the value of the eccentricity (ɛ2) and the triangularity (ɛ3). In turn, upon considering only the events with the highest entropy deposition, i.e., the ultracentral ones, the probability of having larger ɛ2 ,3 increases significantly in the correlated scenario. Finally, the eccentricities show a quite mild energy dependence.

  9. Predictive Capability for Hot Spot Ignition of Double Base Propellants

    DTIC Science & Technology

    2009-08-01

    propellants are composed of nitrocellulose and stirred with a reactive plasticizer liquid nitrate ester such as nitroglycerine which also affects the oxygen...Predictive Capability for Hot Spot Ignition of Double Base Propellants by Stephan R. Bilyk ARL-RP-261 August 2009...Ignition of Double Base Propellants Stephan R. Bilyk Weapons and Materials Research Directorate, ARL A reprint from the 2006

  10. Shock initiation of explosives: High temperature hot spots explained

    NASA Astrophysics Data System (ADS)

    Bassett, Will P.; Johnson, Belinda P.; Neelakantan, Nitin K.; Suslick, Kenneth S.; Dlott, Dana D.

    2017-08-01

    We investigated the shock initiation of energetic materials with a tabletop apparatus that uses km s-1 laser-driven flyer plates to initiate tiny explosive charges and obtains complete temperature histories with a high dynamic range. By comparing various microstructured formulations, including a pentaerythritol tetranitrate (PETN) based plastic explosive (PBX) denoted XTX-8003, we determined that micron-scale pores were needed to create high hot spot temperatures. In charges where micropores (i.e., micron-sized pores) were present, a hot spot temperature of 6000 K was observed; when the micropores were pre-compressed to nm scale, however, the hot spot temperature dropped to ˜4000 K. By comparing XTX-8003 with an analog that replaced PETN by nonvolatile silica, we showed that the high temperatures require gas in the pores, that the high temperatures were created by adiabatic gas compression, and that the temperatures observed can be controlled by the choice of ambient gases. The hot spots persist in shock-compressed PBXs even in vacuum because the initially empty pores became filled with gas created in-situ by shock-induced chemical decomposition.

  11. Variability of Jupiter's Five-Micron Hot Spot Inventory

    NASA Technical Reports Server (NTRS)

    Yanamandra-Fisher, Padma A.; Orton, G. S.; Wakefield, L.; Rogers, J. H.; Simon-Miller, A. A.; Boydstun, K.

    2012-01-01

    Global upheavals on Jupiter involve changes in the albedo of entire axisymmetric regions, lasting several years, with the last two occurring in 1989 and 2006. Against this backdrop of planetary-scale changes, discrete features such as the Great Red Spot (GRS), and other vortices exhibit changes on shorter spatial- and time-scales. We track the variability of the discrete equatorial 5-micron hot spots, semi-evenly spaced in longitude and confined to a narrow latitude band centered at 6.5degN (southern edge of the North Equatorial Belt, NEB), abundant in Voyager images. Tantalizingly similar patterns were observed in the visible (bright plumes and blue-gray regions), where reflectivity in the red is anti-correlated with 5-microns thermal radiance. Ortiz et al. (1998, GRL, 103) characterized the latitude and drift rates of the hot spots, including the descent of the Galileo probe at the southern edge of a 5-micron hot spot, as the superposition of equatorial Rossby waves, with phase speeds between 99 - 103m/s, relative to System III. We note that the high 5-micron radiances correlate well but not perfectly with high 8.57-micron radiances. Because the latter are modulated primarily by changes in the upper ammonia (NH3) ice cloud opacity, this correlation implies that changes in the ammonia ice cloud field may be responsible for the variability seen in the 5-m maps. During the NEB fade (2011 - early 2012), however, these otherwise ubiquitous features were absent, an atmospheric state not seen in decades. The ongoing NEB revival indicates nascent 5-m hot spots as early as April 2012, with corresponding visible dark spots. Their continuing growth through July 2012 indicates the possit.le re-establishment of Rossby waves. The South Equatorial Belt (SEB) and NEB revivals began similarly with an instability that developed into a major outbreak, and many similarities in the observed propagation of clear regions.

  12. Variability of Jupiter's Five-Micron Hot Spot Inventory

    NASA Technical Reports Server (NTRS)

    Yanamandra-Fisher, Padma A.; Orton, G. S.; Wakefield, L.; Rogers, J. H.; Simon-Miller, A. A.; Boydstun, K.

    2012-01-01

    Global upheavals on Jupiter involve changes in the albedo of entire axisymmetric regions, lasting several years, with the last two occurring in 1989 and 2006. Against this backdrop of planetary-scale changes, discrete features such as the Great Red Spot (GRS), and other vortices exhibit changes on shorter spatial- and time-scales. We track the variability of the discrete equatorial 5-micron hot spots, semi-evenly spaced in longitude and confined to a narrow latitude band centered at 6.5degN (southern edge of the North Equatorial Belt, NEB), abundant in Voyager images. Tantalizingly similar patterns were observed in the visible (bright plumes and blue-gray regions), where reflectivity in the red is anti-correlated with 5-microns thermal radiance. Ortiz et al. (1998, GRL, 103) characterized the latitude and drift rates of the hot spots, including the descent of the Galileo probe at the southern edge of a 5-micron hot spot, as the superposition of equatorial Rossby waves, with phase speeds between 99 - 103m/s, relative to System III. We note that the high 5-micron radiances correlate well but not perfectly with high 8.57-micron radiances. Because the latter are modulated primarily by changes in the upper ammonia (NH3) ice cloud opacity, this correlation implies that changes in the ammonia ice cloud field may be responsible for the variability seen in the 5-m maps. During the NEB fade (2011 - early 2012), however, these otherwise ubiquitous features were absent, an atmospheric state not seen in decades. The ongoing NEB revival indicates nascent 5-m hot spots as early as April 2012, with corresponding visible dark spots. Their continuing growth through July 2012 indicates the possit.le re-establishment of Rossby waves. The South Equatorial Belt (SEB) and NEB revivals began similarly with an instability that developed into a major outbreak, and many similarities in the observed propagation of clear regions.

  13. Extracting Hot spots of Topics from Time Stamped Documents.

    PubMed

    Chen, Wei; Chundi, Parvathi

    2011-07-01

    Identifying time periods with a burst of activities related to a topic has been an important problem in analyzing time-stamped documents. In this paper, we propose an approach to extract a hot spot of a given topic in a time-stamped document set. Topics can be basic, containing a simple list of keywords, or complex. Logical relationships such as and, or, and not are used to build complex topics from basic topics. A concept of presence measure of a topic based on fuzzy set theory is introduced to compute the amount of information related to the topic in the document set. Each interval in the time period of the document set is associated with a numeric value which we call the discrepancy score. A high discrepancy score indicates that the documents in the time interval are more focused on the topic than those outside of the time interval. A hot spot of a given topic is defined as a time interval with the highest discrepancy score. We first describe a naive implementation for extracting hot spots. We then construct an algorithm called EHE (Efficient Hot Spot Extraction) using several efficient strategies to improve performance. We also introduce the notion of a topic DAG to facilitate an efficient computation of presence measures of complex topics. The proposed approach is illustrated by several experiments on a subset of the TDT-Pilot Corpus and DBLP conference data set. The experiments show that the proposed EHE algorithm significantly outperforms the naive one, and the extracted hot spots of given topics are meaningful.

  14. Extracting Hot spots of Topics from Time Stamped Documents

    PubMed Central

    Chen, Wei; Chundi, Parvathi

    2011-01-01

    Identifying time periods with a burst of activities related to a topic has been an important problem in analyzing time-stamped documents. In this paper, we propose an approach to extract a hot spot of a given topic in a time-stamped document set. Topics can be basic, containing a simple list of keywords, or complex. Logical relationships such as and, or, and not are used to build complex topics from basic topics. A concept of presence measure of a topic based on fuzzy set theory is introduced to compute the amount of information related to the topic in the document set. Each interval in the time period of the document set is associated with a numeric value which we call the discrepancy score. A high discrepancy score indicates that the documents in the time interval are more focused on the topic than those outside of the time interval. A hot spot of a given topic is defined as a time interval with the highest discrepancy score. We first describe a naive implementation for extracting hot spots. We then construct an algorithm called EHE (Efficient Hot Spot Extraction) using several efficient strategies to improve performance. We also introduce the notion of a topic DAG to facilitate an efficient computation of presence measures of complex topics. The proposed approach is illustrated by several experiments on a subset of the TDT-Pilot Corpus and DBLP conference data set. The experiments show that the proposed EHE algorithm significantly outperforms the naive one, and the extracted hot spots of given topics are meaningful. PMID:21765568

  15. Venusian "hot spots": physical phenomenon and its quantification.

    PubMed

    Goncharov, V P; Gryanik, V M; Pavlov, V I

    2002-12-01

    An overall picture of the Venusian hot spots phenomenon is considered in the framework of the simplest conceptual models that admit the solutions in the form of steadily rotating "hot" vortices. Model assumptions take into account only those features of the middle atmosphere in the polar region of Venus that are supported by observational data and are essential for understanding the physical mechanism initiating similar vortices. The problem is analyzed in the framework of both the pointlike and petal-like models of cyclostrophic vortices. Interpretation of these models as an upper and lower bound of a complete theory allows one to find the region of existence of the regimes responsible for the Venusian hot spots and also to establish and assess numerically conditions under which such vortices can be formed. The emphasis is on a comparison of the theoretically established results with the observational data.

  16. Geochemical "Moats" around Near-ridge Hot Spots

    NASA Astrophysics Data System (ADS)

    Gale, A.; Langmuir, C. H.

    2015-12-01

    It has long been known that ridge basalts tend to become enriched in both isotopic and incompatible trace element ratios with proximity to a hot spot. Less recognized is that at a certain distance from the hot spot, samples are relatively depleted in moderately incompatible element ratios (e.g., Zr/Y, Dy/Yb) even as the enrichment in highly incompatible element ratios (e.g., Ba/La, La/Sm) persists. This leads in some cases to trace element patterns that are concave downward for moderately incompatible elements, indicating a depleted source, and concave upward for highly incompatible elements, indicating an enriched source. Clear offsets for samples near hot spots exist on plots such as Ba/La vs. Dy/Yb, and they also often have low Na8.0 for their depth. Areas where such geochemical characteristics occur are adjacent to hot spots—they form a kind of geochemical "moat" of combined depletion and enrichment. Moats can result from two sequential processes: first removal of a melt in the presence of garnet, leading to a source with low Dy/Yb, etc., followed by addition of a low-degree (low F) enriched melt to produce incompatible element and isotope enrichment. Two hypotheses for the moats are (1) they result from recent plume flow, where mantle that loses melt to the hot spot center is refertilized and enriched as it flows down the ridge. (2) Increased melting associated with a hot spot permits melting of ancient sources depleted by melt loss in the presence of garnet. High Hf isotopes for some moat samples from the N. Atlantic support model (2). Geochemical moats have global regularities. Using segment means from previous work, we show that the maximum distance of a moat segment from a hot spot correlates with plume flux normalized to spreading rate, with an R2 >0.9. A higher plume flux at slower spreading rates creates a larger moat. While high Hf isotopes are typical of N. Atlantic moat samples, this is not the case near Afar and Galapagos. This supports model (1

  17. Effects of EOS adiabat on hot spot dynamics

    NASA Astrophysics Data System (ADS)

    Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Batha, Steven

    2013-10-01

    Equation of state (EOS) and adiabat of the pusher play significant roles in the dynamics and formation of the hot spot of an ignition capsule. For given imploding energy, they uniquely determine the partition of internal energy, mass, and volume between the pusher and the hot spot. In this work, we apply the new scaling laws recently derived by Cheng et al. to the National Ignition Campaign (NIC) ignition capsules and study the impacts of EOS and adiabat of the pusher on the hot spot dynamics by using the EOS adiabat index as an adjustable model parameter. We compare our analysis with the NIC data, specifically, for shots N120321 and N120205, and with the numerical simulations of these shots. The predictions from our theoretical model are in good agreements with the NIC data when a hot adiabat was used for the pusher, and with code simulations when a cold adiabat was used for the pusher. Our analysis indicates that the actual adiabat of the pusher in NIC experiments may well be higher than the adiabat assumed in the simulations. This analysis provides a physical and systematic explanation to the ongoing disagreements between the NIC experimental results and the multi-dimensional numerical simulations. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under contract number W-7405-ENG-36.

  18. Magnetic-Responsive Release Controlled by Hot Spot Effect.

    PubMed

    Guisasola, Eduardo; Baeza, Alejandro; Talelli, Marina; Arcos, Daniel; Moros, María; de la Fuente, Jesús M; Vallet-Regí, María

    2015-11-24

    Magnetically triggered drug delivery nanodevices have attracted great attention in nanomedicine, as they can feature as smart carriers releasing their payload at clinician's will. The key principle of these devices is based on the properties of magnetic cores to generate thermal energy in the presence of an alternating magnetic field. Then, the temperature increase triggers the drug release. Despite this potential, the rapid heat dissipation in living tissues is a serious hindrance for their clinical application. It is hypothesized that magnetic cores could act as hot spots, this is, produce enough heat to trigger the release without the necessity to increase the global temperature. Herein, a nanocarrier has been designed to respond when the temperature reaches 43 °C. This material has been able to release its payload under an alternating magnetic field without the need of increasing the global temperature of the environment, proving the efficacy of the hot spot mechanism in magnetic-responsive drug delivery devices.

  19. Structural hot spots for the solubility of globular proteins

    PubMed Central

    Ganesan, Ashok; Siekierska, Aleksandra; Beerten, Jacinte; Brams, Marijke; Van Durme, Joost; De Baets, Greet; Van der Kant, Rob; Gallardo, Rodrigo; Ramakers, Meine; Langenberg, Tobias; Wilkinson, Hannah; De Smet, Frederik; Ulens, Chris; Rousseau, Frederic; Schymkowitz, Joost

    2016-01-01

    Natural selection shapes protein solubility to physiological requirements and recombinant applications that require higher protein concentrations are often problematic. This raises the question whether the solubility of natural protein sequences can be improved. We here show an anti-correlation between the number of aggregation prone regions (APRs) in a protein sequence and its solubility, suggesting that mutational suppression of APRs provides a simple strategy to increase protein solubility. We show that mutations at specific positions within a protein structure can act as APR suppressors without affecting protein stability. These hot spots for protein solubility are both structure and sequence dependent but can be computationally predicted. We demonstrate this by reducing the aggregation of human α-galactosidase and protective antigen of Bacillus anthracis through mutation. Our results indicate that many proteins possess hot spots allowing to adapt protein solubility independently of structure and function. PMID:26905391

  20. Hot spots in density fingering of exothermic autocatalytic chemical fronts.

    PubMed

    Gérard, T; Tóth, T; Grosfils, P; Horváth, D; De Wit, A; Tóth, A

    2012-07-01

    Measurements of two-dimensional (2D) temperature fields are performed by an interferometric method during density fingering of the autocatalytic chlorite-tetrathionate reaction in a Hele-Shaw cell. These measures confirm that, because of heat losses through the glass walls of the reactor, the temperature profile across the front is a pulse rather than a front. Moreover, the full 2D temperature field shows the presence in the reactive zone of hot spots where the temperature exceeds the maximum temperature measured in a stable planar front. We investigate here experimentally the increase of temperature in the hot spots when the composition of the reactants is varied to increase the exothermicity of the reaction. We back up these experimental observations by nonlinear simulations of a reaction-diffusion-convection model which show that the maximum temperature reached in the system depends on the intensity of convection.

  1. Calculated occultation profiles of Io and the hot spots

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.; Soderblom, L. A.; Matson, D. L.; Johnson, T. V.; Lunine, J. I.

    1986-01-01

    Occultations of Io by other Galilean satellites in 1985 provide a means to locate volcanic hot spots and to model their temperatures. The expected time variations in the integral reflected and emitted radiation of the occultations are computed as a function of wavelength (visual to 8.7 microns). The best current ephemerides were used to calculate the geometry of each event as viewed from earth. Visual reflectances were modeled from global mosaics of Io. Thermal emission from the hot spots was calculated from Voyager 1 IRIS observations and, for regions unobserved by IRIS, from a model based on the distribution of low-albedo features. The occultations may help determine (1) the location and temperature distribution of Loki; (2) the source(s) of excess emission in the region from long 50 deg to 200 deg and (3) the distribution of small, high-temperature sources.

  2. RAS gene hot-spot mutations in canine neoplasias.

    PubMed

    Richter, A; Murua Escobar, H; Günther, K; Soller, J T; Winkler, S; Nolte, I; Bullerdiek, J

    2005-01-01

    Point mutations in the cellular homologues HRAS, KRAS2, and NRAS of the viral Harvey and Kirsten rat sarcoma virus oncogenes are commonly involved in the onset of malignancies in humans and other species such as dog, mouse, and rat. Most often, three particular hot-spot codons are affected, with one amino acid exchange being sufficient for the induction of tumor growth. While RAS genes have been shown to play an important role in canine tumors such as non-small lung cell carcinomas, data about RAS mutations in canine fibrosarcomas as well as KRAS2 mutations in canine melanomas is sparse. To increase the number of tumors examined, we recently screened 13 canine fibrosarcomas and 11 canine melanomas for point mutations, particularly within the mutational hot spots. The results were compared to the already existing data from other studies about these tumors in dogs.

  3. Hot-spot evolution and the global tectonics of Venus

    SciTech Connect

    Phillips, R.J.; Grimm, R.E. ); Malin, M.C. )

    1991-05-03

    The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging of the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (1) a broad domal uplift resulting from a rising mantle plume, (2) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (3) collapse of dynamic topography, and (4) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading.

  4. Hot spots, indicator taxa, complementarity and optimal networks of taiga.

    PubMed Central

    Virolainen, K M; Ahlroth, P; Hyvärinen, E; Korkeamäki, E; Mattila, J; Päiivinen, J; Rintala, T; Suomi, T; Suhonen, J

    2000-01-01

    If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important group indicating the conservation value of old growth taiga forests. Random selection provided a better option. Thus, certain groups may function as good indicators for maximizing the overall species richness of some taxonomic groups, but all taxa should be examined separately. PMID:10885520

  5. Structural hot spots for the solubility of globular proteins.

    PubMed

    Ganesan, Ashok; Siekierska, Aleksandra; Beerten, Jacinte; Brams, Marijke; Van Durme, Joost; De Baets, Greet; Van der Kant, Rob; Gallardo, Rodrigo; Ramakers, Meine; Langenberg, Tobias; Wilkinson, Hannah; De Smet, Frederik; Ulens, Chris; Rousseau, Frederic; Schymkowitz, Joost

    2016-02-24

    Natural selection shapes protein solubility to physiological requirements and recombinant applications that require higher protein concentrations are often problematic. This raises the question whether the solubility of natural protein sequences can be improved. We here show an anti-correlation between the number of aggregation prone regions (APRs) in a protein sequence and its solubility, suggesting that mutational suppression of APRs provides a simple strategy to increase protein solubility. We show that mutations at specific positions within a protein structure can act as APR suppressors without affecting protein stability. These hot spots for protein solubility are both structure and sequence dependent but can be computationally predicted. We demonstrate this by reducing the aggregation of human α-galactosidase and protective antigen of Bacillus anthracis through mutation. Our results indicate that many proteins possess hot spots allowing to adapt protein solubility independently of structure and function.

  6. Astroparticle transport and yield in extragalactic jets and hot spots

    NASA Astrophysics Data System (ADS)

    Marcowith, A.; Casse, F.

    2005-02-01

    The present work discusses yield and transport of high-energy particle within extragalactic jet terminal shocks, also known as hotspots. These astrophysical sources are responsible for strong non-thermal synchrotron emission produced by relativistic electrons accelerated via a Fermi-type mechanism. We investigate in some details the cosmic ray, neutrinos and high-energy photons yield in hotspots of powerful FRII radio-galaxies by scanning all known spatial transport regimes, adiabatic and radiative losses as well as Fermi acceleration processes. Since both electrons and cosmic rays are prone to the same type of acceleration, we derive analytical estimates of the maximal cosmic ray energy attainable in both toroidal and poloidal magnetic field dominated shock structures by using observational data on synchrotron emission coming from various hot-spots. One of our main conclusions is that the best hot-spot candidates for high energy astroparticle production is the extended (LHS >= 1kpc), strongly magnetized (B > 0.1mG) terminal shock displaying synchrotron emission cut-off lying at least in the optical band. We found only one object (3C273A) over the six objects in our sample being capable to produce cosmic rays up to 1020 eV. We also show that the Bohm regime is unlikely to occur in the whole hot-spot since it would require unrealistically low jet velocities. We finally investigate the astroparticle yields of a characteric cosmic-ray loud hot-spot and compared them to the sensibilities of the future neutrinos and gamma-ray missions.

  7. Thermal imaging of hot spots in nanostructured microstripes

    NASA Astrophysics Data System (ADS)

    Saïdi, E.; Lesueur, J.; Aigouy, L.; Labéguerie-Egéa, J.; Mortier, M.

    2010-03-01

    By scanning thermal microscopy, we study the behavior of nanostructured metallic microstripes heated by Joule effect. Regularly spaced indentations have been made along the thin film stripe in order to create hot spots. For the designed stripe geometry, we observe that heat remains confined in the wire and in particular at shrinkage points within ~1μm2. Thermal maps have been obtained with a good lateral resolution (< 300nm) and a good temperature sensitivity (~1K).

  8. A pulsating auroral X-ray hot spot on Jupiter.

    PubMed

    Gladstone, G R; Waite, J H; Grodent, D; Lewis, W S; Crary, F J; Elsner, R F; Weisskopf, M C; Majeed, T; Jahn, J-M; Bhardwaj, A; Clarke, J T; Young, D T; Dougherty, M K; Espinosa, S A; Cravens, T E

    2002-02-28

    Jupiter's X-ray aurora has been thought to be excited by energetic sulphur and oxygen ions precipitating from the inner magnetosphere into the planet's polar regions. Here we report high-spatial-resolution observations that demonstrate that most of Jupiter's northern auroral X-rays come from a 'hot spot' located significantly poleward of the latitudes connected to the inner magnetosphere. The hot spot seems to be fixed in magnetic latitude and longitude and occurs in a region where anomalous infrared and ultraviolet emissions have also been observed. We infer from the data that the particles that excite the aurora originate in the outer magnetosphere. The hot spot X-rays pulsate with an approximately 45-min period, a period similar to that reported for high-latitude radio and energetic electron bursts observed by near-Jupiter spacecraft. These results invalidate the idea that jovian auroral X-ray emissions are mainly excited by steady precipitation of energetic heavy ions from the inner magnetosphere. Instead, the X-rays seem to result from currently unexplained processes in the outer magnetosphere that produce highly localized and highly variable emissions over an extremely wide range of wavelengths.

  9. Raman spectroelectrochemistry of molecules within individual electromagnetic hot spots.

    PubMed

    Shegai, Timur; Vaskevich, Alexander; Rubinstein, Israel; Haran, Gilad

    2009-10-14

    The role of chemical enhancement in surface-enhanced Raman scattering (SERS) remains a contested subject. We study SERS spectra of 4-mercaptopyridine molecules excited far from the molecular resonance, which are collected from individual electromagnetic hot spots at concentrations close to the single-molecule limit. The hot spots are created by depositing Tollen's silver island films on a transparent electrode incorporated within an electrochemical cell. Analysis of the intensity of the spectra relative to those obtained from individual rhodamine 6G molecules on the same surface provides a lower limit of approximately 3 orders of magnitude for the chemical enhancement. This large enhancement is likely to be due to a charge transfer resonance involving the transfer of an electron from the metal to an adsorbed molecule. Excitation at three different wavelengths, as well as variation of electrode potential from 0 to -1.2 V, lead to significant changes in the relative intensities of bands in the spectrum. It is suggested that while the bulk of the enhancement is due to an Albrecht A-term resonance Raman effect (involving the charge transfer transition), vibronic coupling provides additional enhancement which is sensitive to electrode potential. The measurement of potential-dependent SERS spectra from individual hot spots opens the way to a thorough characterization of chemical enhancement, as well to studies of redox phenomena at the single-molecule level.

  10. Climate impacts on global hot spots of marine biodiversity

    PubMed Central

    Ramírez, Francisco; Afán, Isabel; Davis, Lloyd S.; Chiaradia, André

    2017-01-01

    Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world’s richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation. PMID:28261659

  11. Hot spot mix in ICF implosions on the NIF

    NASA Astrophysics Data System (ADS)

    Ma, Tammy

    2016-10-01

    In the quest to achieve ignition through the inertial confinement fusion scheme, one of the critical challenges is to drive a symmetric implosion at high velocity without hydrodynamic instabilities becoming detrimental. These instabilities, primarily at the ablation front and the fuel-ablator interface, can cause mix of the higher-Z shell into the hot spot, resulting in increased radiation loss and thus reduced temperature and neutron yield. To quantify the level of mix, we developed a model that infers the level of hot spot contamination using the ratio of the enhanced x-ray production relative to the neutron yield. Applying this methodology to the full ensemble of indirect-drive National Ignition Facility (NIF) cryogenically layered DT implosions provides insight on the sensitivity of performance to the level of ablator-hot spot mix. In particular, the improvement seen with the High Foot design can be primarily attributed to a reduction in ablation-front instability mix that enabled the implosions to be pushed to higher velocity and performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, Lawrence Livermore National Security, LLC.

  12. Climate impacts on global hot spots of marine biodiversity.

    PubMed

    Ramírez, Francisco; Afán, Isabel; Davis, Lloyd S; Chiaradia, André

    2017-02-01

    Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world's richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation.

  13. Distinguishing black holes and wormholes with orbiting hot spots

    NASA Astrophysics Data System (ADS)

    Li, Zilong; Bambi, Cosimo

    2014-07-01

    The supermassive black hole candidates at the center of every normal galaxy might be wormholes created in the early Universe and connecting either two different regions of our Universe or two different universes in a multiverse model. Indeed, the origin of these supermassive objects is not well understood; topological nontrivial structures like wormholes are allowed both in general relativity and in alternative theories of gravity, and current observations cannot rule out such a possibility. In a few years, the VLTI instrument GRAVITY will have the capability to image blobs of plasma orbiting near the innermost stable circular orbit of SgrA*, the supermassive black hole candidate in the Milky Way. The secondary image of a hot spot orbiting around a wormhole is substantially different from that of a hot spot around a black hole, because the photon capture sphere of the wormhole is much smaller. The radius of the photon capture sphere is independent of the hot spot model, and therefore its possible detection, which is observationally challenging but not out of reach, can unambiguously test if the center of our Galaxy harbors a wormhole rather than a black hole.

  14. Hot spot management through design based metrology: measurement and filtering

    NASA Astrophysics Data System (ADS)

    Lee, Taehyeong; Yang, Hyunjo; Kim, Jungchan; Jung, Areum; Yoo, Gyun; Yim, Donggyu; Park, Sungki; Ishikawa, Akio; Yamamoto, Masahiro; Vikram, Abhishek

    2009-12-01

    Recently several Design Based Metrologies (DBMs) are introduced and being in use for wafer verification. The major applications of DBM are OPC accuracy improvement, DFM feed-back through Process Window Qualification (PWQ) and advanced process control. In general, however, the amount of output data from DBM is normally so large that it is very hard to handle the data for valuable feed-back. In case of PWQ, more than thousands of hot spots are detected on a single chip at the edge of process window. So, it takes much time and labor to review and analyze all the hot spots detected at PWQ. Design-related systematic defects, however, will be found repeatedly and if they can be classified into groups, it would be possible to save a lot of time for the analysis. We have demonstrated an EDA tool which can handle the large amount of output data from DBM by classifying pattern defects into groups. It can classify millions of patterns into less than thousands of pattern groups. It has been evaluated on the analysis of PWQ of metal layer in NAND Flash memory device and random contact hole patterns in a DRAM device. Also, verification was tuned to specific needs of the designer as well as defect analysis engineers by use of EDA tool's 'Pattern Matching Function'. The verification result was well within the required specification of the designer as well as the analysis engineer. The procedures of Hot Spot Management through Design Based Metrology are presented in detail.

  15. Variation in the Deep Gas Composition in Hot Spots on Jupiter

    NASA Astrophysics Data System (ADS)

    Bjoraker, Gordon; de Pater, Imke; Wong, Michael H.; Adamkovics, Mate; Hewagama, Tilak; Hesman, Brigette

    2015-11-01

    We used CSHELL on NASA’s Infrared Telescope Facility and NIRSPEC on the Keck telescope in the last two years to spectrally resolve line profiles of CH3D, NH3, PH3, and H2O in 5-micron Hot Spots on Jupiter. The profile of the CH3D lines at 4.66 microns is very broad in both NEB and SEB Hot Spots due to collisions with up to 8 bars of H2, where unit optical depth occurs due to collision-induced H2 opacity. The extreme width of these CH3D features implies that the Hot Spots that we observed do not have significant cloud opacity for P > 2 bars. We retrieved NH3, PH3, and gaseous H2O within Hot Spots in both the NEB and SEB. We had dry nights on Mauna Kea and a sufficient Doppler shift to detect H2O. We will compare line wings to derive H2O profiles in the 2 to 6-bar region. NEB Hot Spots are depleted in NH3 with respect to adjacent regions. Interestingly, SEB Hot Spots exhibit stronger NH3 absorption than NEB Hot Spots. In addition, SEB Hot Spots have very similar 5-micron spectra as neighboring longitudes in the SEB, implying similar deep gas composition. The dynamical origin of SEB Hot Spots is much less studied than that of NEB Hot Spots, so our observations of gas composition in both regions may constrain mechanisms for forming Hot Spots.

  16. Hot spot-based design of small-molecule inhibitors for protein-protein interactions.

    PubMed

    Guo, Wenxing; Wisniewski, John A; Ji, Haitao

    2014-06-01

    Protein-protein interactions (PPIs) are important targets for the development of chemical probes and therapeutic agents. From the initial discovery of the existence of hot spots at PPI interfaces, it has been proposed that hot spots might provide the key for developing small-molecule PPI inhibitors. However, there has been no review on the ways in which the knowledge of hot spots can be used to achieve inhibitor design, nor critical examination of successful examples. This Digest discusses the characteristics of hot spots and the identification of druggable hot spot pockets. An analysis of four examples of hot spot-based design reveals the importance of this strategy in discovering potent and selective PPI inhibitors. A general procedure for hot spot-based design of PPI inhibitors is outlined. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Hot spots and hot moments in riparian zones: Potential for improved water quality management

    Treesearch

    Philippe Vidon; Craig Allan; Douglas Burns; Tim P. Duval; Noel Gurwick; Shreeram Inamdar; Richard Lowrance; Judy Okay; Durelle Scott; Stephen Sebestyen

    2010-01-01

    Biogeochemical and hydrological processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. These heterogeneous processes have recently been conceptualized as "hot spots and moments" of retention, degradation, or production. Nevertheless, studies investigating...

  18. Anomalous ultrafast dynamics of hot plasmonic electrons in nanostructures with hot spots.

    PubMed

    Harutyunyan, Hayk; Martinson, Alex B F; Rosenmann, Daniel; Khorashad, Larousse Khosravi; Besteiro, Lucas V; Govorov, Alexander O; Wiederrecht, Gary P

    2015-09-01

    The interaction of light and matter in metallic nanosystems is mediated by the collective oscillation of surface electrons, called plasmons. After excitation, plasmons are absorbed by the metal electrons through inter- and intraband transitions, creating a highly non-thermal distribution of electrons. The electron population then decays through electron-electron interactions, creating a hot electron distribution within a few hundred femtoseconds, followed by a further relaxation via electron-phonon scattering on the timescale of a few picoseconds. In the spectral domain, hot plasmonic electrons induce changes to the plasmonic resonance of the nanostructure by modifying the dielectric constant of the metal. Here, we report on the observation of anomalously strong changes to the ultrafast temporal and spectral responses of these excited hot plasmonic electrons in hybrid metal/oxide nanostructures as a result of varying the geometry and composition of the nanostructure and the excitation wavelength. In particular, we show a large ultrafast, pulsewidth-limited contribution to the excited electron decay signal in hybrid nanostructures containing hot spots. The intensity of this contribution correlates with the efficiency of the generation of highly excited surface electrons. Using theoretical models, we attribute this effect to the generation of hot plasmonic electrons from hot spots. We then develop general principles to enhance the generation of energetic electrons through specifically designed plasmonic nanostructures that could be used in applications where hot electron generation is beneficial, such as in solar photocatalysis, photodetectors and nonlinear devices.

  19. Anomalous ultrafast dynamics of hot plasmonic electrons in nanostructures with hot spots

    DOE PAGES

    Harutyunyan, Hayk; Martinson, Alex B. F.; Rosenmann, Daniel; ...

    2015-08-03

    The interaction of light and matter in metallic nanosystems is mediated by the collective oscillation of surface electrons, called plasmons. After excitation, plasmons are absorbed by the metal electrons through inter- and intraband transitions, creating a highly non-thermal distribution of electrons. The electron population then decays through electron-electron interactions, creating a hot electron distribution within a few hundred femtoseconds, followed by a further relaxation via electron-phonon scattering on the timescale of a few pico-seconds. In the spectral domain, hot plasmonic electrons induce changes to the plasmonic resonance of the nanostructure by modifying the dielectric constant of the metal. Here, wemore » report on the observation of anomalously strong changes to the ultrafast temporal and spectral responses of these excited hot plasmonic electrons in hybrid metal/oxide nanostructures as a result of varying the geometry and composition of the nanostructure and the excitation wavelength. In particular, we show a large ultrafast, pulsewidth-limited contribution to the excited electron decay signal in hybrid nanostructures containing hot spots. The intensity of this contribution correlates with the efficiency of the generation of highly excited surface electrons. Using theoretical models, we attribute this effect to the generation of hot plasmonic electrons from hot spots. Finally, we then develop general principles to enhance the generation of energetic electrons through specifically designed plasmonic nanostructures that could be used in applications where hot electron generation is beneficial, such as in solar photocatalysis, photodetectors and nonlinear devices.« less

  20. Anomalous ultrafast dynamics of hot plasmonic electrons in nanostructures with hot spots

    SciTech Connect

    Harutyunyan, Hayk; Martinson, Alex B. F.; Rosenmann, Daniel; Khorashad, Larousse Khosravi; Besteiro, Lucas V.; Govorov, Alexander O.; Wiederrecht, Gary P.

    2015-08-03

    The interaction of light and matter in metallic nanosystems is mediated by the collective oscillation of surface electrons, called plasmons. After excitation, plasmons are absorbed by the metal electrons through inter- and intraband transitions, creating a highly non-thermal distribution of electrons. The electron population then decays through electron-electron interactions, creating a hot electron distribution within a few hundred femtoseconds, followed by a further relaxation via electron-phonon scattering on the timescale of a few pico-seconds. In the spectral domain, hot plasmonic electrons induce changes to the plasmonic resonance of the nanostructure by modifying the dielectric constant of the metal. Here, we report on the observation of anomalously strong changes to the ultrafast temporal and spectral responses of these excited hot plasmonic electrons in hybrid metal/oxide nanostructures as a result of varying the geometry and composition of the nanostructure and the excitation wavelength. In particular, we show a large ultrafast, pulsewidth-limited contribution to the excited electron decay signal in hybrid nanostructures containing hot spots. The intensity of this contribution correlates with the efficiency of the generation of highly excited surface electrons. Using theoretical models, we attribute this effect to the generation of hot plasmonic electrons from hot spots. Finally, we then develop general principles to enhance the generation of energetic electrons through specifically designed plasmonic nanostructures that could be used in applications where hot electron generation is beneficial, such as in solar photocatalysis, photodetectors and nonlinear devices.

  1. Association of poly-purine/poly-pyrimidine sequences with meiotic recombination hot spots

    PubMed Central

    Bagshaw, Andrew TM; Pitt, Joel PW; Gemmell, Neil J

    2006-01-01

    Background Meiotic recombination events have been found to concentrate in 1–2.5 kilo base regions, but these recombination hot spots do not share a consensus sequence and why they occur at specific sites is not fully understood. Some previous evidence suggests that poly-purine/poly-pyrimidine (poly-pu/py) tracts (PPTs), a class of sequence with distinctive biochemical properties, could be involved in recombination, but no general association of PPTs with meiotic recombination hot spots has previously been reported. Results We used computational methods to investigate in detail the relationship between PPTs and hot spots. We show statistical associations of PPT frequency with hot spots of meiotic recombination initiating lesions, double-strand breaks, in the genome of the yeast S. cerevisiae and with experimentally well characterized human meiotic recombination hot spots. Supporting a possible role of poly-pu/py-rich sequences in hot spot recombination, we also found that all three single nucleotide polymorphisms previously shown to be associated with human hot spot activity changes occur within sequence contexts of 14 bp or longer that are 85% or more poly-pu/py and at least 70% G/C. These polymorphisms are all close to the hot spot mid points. Comparing the sequences of experimentally characterized human hot spots with the orthologous regions of the chimpanzee genome previously shown not to contain hot spots, we found that in all five cases in which comparisons for the hot spot central regions are possible with publicly available sequence data, there are differences near the human hot spot mid points within sequences 14 bp or longer consisting of more than 80% poly-pu/py and at least 50% G/C. Conclusion Our results, along with previous evidence for the unique biochemical properties and recombination-stimulating potential of poly-pu/py-rich sequences, suggest that the possible functional involvement of this type of sequence in meiotic recombination hot spots

  2. GEOMETRICAL CONSTRAINTS ON THE HOT SPOT IN BETA LYRAE

    SciTech Connect

    Lomax, Jamie R.; Hoffman, Jennifer L.; Elias II, Nicholas M.; Bastien, Fabienne A.; Holenstein, Bruce D. E-mail: Jennifer.Hoffman@du.edu E-mail: fabienne.a.bastien@vanderbilt.edu

    2012-05-01

    We present results from six years of recalibrated and new spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and six years of new data taken with the photoelastic modulating polarimeter at the Flower and Cook Observatory of beta Lyrae. Combining these data with polarimetric data from the literature allows us to characterize the intrinsic BVRI polarized light curves. A repeatable discrepancy of 0.245 days (approximately 6 hr) between the secondary minima in the total light curve and the polarization curve in the V band, with similar behavior in the other bands, may represent the first direct evidence for an accretion hot spot on the disk edge.

  3. Hot spots and dark current in advanced plasma wakefield accelerators

    DOE PAGES

    Manahan, G. G.; Deng, A.; Karger, O.; ...

    2016-01-29

    Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. Likewise, these electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. The strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  4. Hot spots and dark current in advanced plasma wakefield accelerators

    DOE PAGES

    Manahan, G.; Deng, A.; Karger, O.; ...

    2016-01-01

    Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  5. Current-induced forces and hot spots in biased nanojunctions.

    PubMed

    Lü, Jing-Tao; Christensen, Rasmus B; Wang, Jian-Sheng; Hedegård, Per; Brandbyge, Mads

    2015-03-06

    We investigate theoretically the interplay of current-induced forces (CIFs), Joule heating, and heat transport inside a current-carrying nanoconductor. We find that the CIFs, due to the electron-phonon coherence, can control the spatial heat dissipation in the conductor. This yields a significant asymmetric concentration of excess heating (hot spot) even for a symmetric conductor. When coupled to the electrode phonons, CIFs drive different phonon heat flux into the two electrodes. First-principles calculations on realistic biased nanojunctions illustrate the importance of the effect.

  6. Omar field discovery confirms Syria as exploration hot spot

    SciTech Connect

    Not Available

    1988-06-20

    Syria is proving to be one of the Mediterranean's exploration hot spots. The discovery of Omar field by a Shell-led exploration group earlier this year confirmed Syria as a prime exploration prospect. For years Syria produced small volumes of heavy, high-sulfur crude mainly for refining and use in the domestic market and found it difficult to attract foreign explorers. Industry sources say there is now no shortage of outside industry interest in taking new exploration concessions. Over the last 6 months much of the available prospective acreage has been taken up as industry interest in Syria reached nee heights.

  7. PEBBED ANALYSIS OF HOT SPOTS IN PEBBLE-BED REACTORS

    SciTech Connect

    Abderrafi M. Ougouag; Hans D. Gougar; William K. Terry; Frederik Reitsma; Wessel Joubert

    2005-09-01

    The Idaho National Laboratory’s PEBBED code and simple probability considerations are used to estimate the likelihood and consequences of the accumulation of highly reactive pebbles in the region of peak power in a pebble-bed reactor. The PEBBED code is briefly described, and the logic of the probability calculations is presented in detail. The results of the calculations appear to show that hot-spot formation produces only moderate increases in peak accident temperatures, and no increases at all in normal operating temperatures.

  8. Automated hot-spot fixing system applied for metal layers of 65 nm logic devices

    NASA Astrophysics Data System (ADS)

    Kobayashi, Sachiko; Kyoh, Suigen; Kotani, Toshiya; Tanaka, Satoshi; Inoue, Soichi

    2006-05-01

    Hot spot clearance using process simulation is indispensable under low-k1 lithography process for logic devices of 65 nm and below. Hot spots such as pinching, bridging, line-end shortening will occur, mainly depending on local pattern context. Appropriate calibration of design rule (DR), mask data preparation (MDP), resolution enhancement technique (RET) and optical proximity effect correction (OPC) will reduce potential hot spots. However, pattern layout variety is so enormous that, even with the most careful calibration of every process, an unexpected potential hot spot is occasionally left in the design layout. Manual modification of design at hot spot will be effective, but it takes too much time to determine how to modify layout to be consistent with DR, MDP/OPC rule, and the process often needs to be iterative. Therefore, there is a need for an automated hot spot fixing system is capable of fixing design layout so as to avoid fatal hot spot occurrence, with sufficient process margin and short turn around time (TAT). We developed an automated hot-spot fixing system, Hot Spot Fixer (HSF). The basic system flow in the developed system is as follows; Design data is processed with the conventional mask data preparation process. Then, process simulation is performed to extract hot spots. The hot spots are categorized by lithography error mode, critical level, and surrounding context. An intelligent hot-spot modification instructor, taking the surrounding situation into consideration, generates modification guide for the every hot spot. Design data is automatically modified according to the instruction at every hot spot, complying with the design rule. If necessary, several modification candidates are indicated and the user can choose the most adequate one from them. The design modification process is verified from every aspect, using Design Rule Checker (DRC) and process simulation. The modified design data, with reduced potential hot spot compared with pre

  9. Hot spots in the NGC 2071 molecular outflow

    NASA Astrophysics Data System (ADS)

    Chernin, Lawrence M.; Welch, W. J.

    1995-02-01

    In this Letter we present high spatial resolution (7 sec) images, obtained with the Berkeley-Illinois-Maryland Association (BIMA) interferometer, of the 47-66 km/s CO J = 1-0 emission in the redshifted lobe of the NGC 2071 molecular outflow. The 47-66 km/s CO, hereafter referred to as the extremely high velocity (EHV) feature, has mass 0.01 solar mass, temperature 50 K, and density 2 x 105/cu cm, and is spatially compact and spectrally distinct from the swept-up flow (3.5 solar mass). The EHV emission region consists of three main peaks which are individually unresolved by the interferometer beam. The EHV peaks resemble the 'hot spots' found in the lobes of extragalactic radio sources. Since the EHV emission does not trace the outline of any of the known clumps in the outflow lobe, the EHV emission cannot be modeled as clumps being accelerated by a wind. Instead, we propose that the hot spots are caused by the (unseen)jet striking a known clump; either the jet bow shock fragments, or there are multiple bow shocks formed by a wandering jet.

  10. Hot Spots in the NGC 2071 Molecular Outflow

    NASA Astrophysics Data System (ADS)

    Chernin, L. M.; Welch, W. J.

    1995-03-01

    In this letter, we present high spatial resolution (7") images, obtained with the BIMA interferometer, of the 47-66 km/s CO J=1-0 emission in the redshifted lobe of the NGC 2071 molecular outflow. The 47-66 km/s CO, hereafter referred to as the extremely high velocity (EHV) feature, has a mass of 0.01 solar masses, temperature of 50 K, density of 2 x 10^5 per cubic cm, and is spatially compact and spectrally distinct from the swept-up flow (3.5 solar masses). The EHV emission region consists of three main peaks which are individually unresolved by the interferometer beam. The EHV peaks resemble the ``hot spots'' found in the lobes of extragalactic radio sources. Since the EHV emission does not trace the outline of any of the known clumps in the outflow lobe, the EHV emission cannot be modeled as clumps being accelerated by a wind. Instead, we propose that the hot spots are caused by the (unseen) jet striking a known clump, and either the jet-bow shock fragments, or there are multiple bow shocks formed by a wandering jet.

  11. Detecting traffic hot spots using vehicle tracking data

    NASA Astrophysics Data System (ADS)

    Xu, Zhimin; Lin, Zhiyong; Zhou, Cheng; Huang, Changqing

    2016-03-01

    Vehicle tracking data for thousands of urban vehicles and the availability of digital map provide urban planners unprecedented opportunities for better understanding urban transportation. In this paper, we aim to detect traffic hot spots on urban road networks using vehicle tracking data. Our approach first proposes an integrated map-matching algorithm based on the road buffer and vehicle driving direction, to find out which road segment the vehicle is travelling on. Then, we estimate travel speed by calculating the average the speed of every vehicle on a certain road segment, which indicates traffic status, and create the spatial weights matrices based on the connectivity of road segments, which expresses the spatial dependence between each road segment. Finally, the measure of global and local spatial autocorrelation is used to evaluate the spatial distribution of the traffic condition and reveal the traffic hot spots on the road networks. Experiments based on the taxi tracking data and urban road network data from Wuhan have been performed to validate the detection effectiveness.

  12. Hot spot-derived shock initiation phenomena in heterogeneous nitromethane

    SciTech Connect

    Dattelbaum, Dana M; Sheffield, Stephen A; Stahl, David B; Dattelbaum, Andrew M

    2009-01-01

    The addition of solid silica particles to gelled nitromethane offers a tractable model system for interrogating the role of impedance mismatches as one type of hot spot 'seed' on the initiation behaviors of explosive formulations. Gas gun-driven plate impact experiments are used to produce well-defined shock inputs into nitromethane-silica mixtures containing size-selected silica beads at 6 wt%. The Pop-plots or relationships between shock input pressure and rundistance (or time)-to-detonation for mixtures containing small (1-4 {micro}m) and large (40 {micro}m) beads are presented. Overall, the addition of beads was found to influence the shock sensitivity of the mixtures, with the smaller beads being more sensitizing than the larger beads, lowering the shock initiation threshold for the same run distance to detonation compared with neat nitromethane. In addition, the use of embedded electromagnetic gauges provides detailed information pertaining to the mechanism of the build-up to detonation and associated reactive flow. Of note, an initiation mechanism characteristic of homogeneous liquid explosives, such as nitromethane, was observed in the nitromethane-40 {micro}m diameter silica samples at high shock input pressures, indicating that the influence of hot spots on the initiation process was minimal under these conditions.

  13. Hot Spots from Dislocation Pile-up Avalanches

    NASA Astrophysics Data System (ADS)

    Armstrong, Ronald; Grise, William

    2005-07-01

    The model of hot spots developed at dislocation pile-up avalanches has been employed to explain both: greater drop- weight heights being required to initiate chemical decomposition of smaller crystals [1]; and, the susceptibility to shear banding of energetic and reference inert materials, for example, adiabatic shear banding in steel [2]. The evidence for RDX (cyclotrimethylenetrinitramine) is that few dislocations are needed in the pile-ups thus providing justification for assessing dynamic pile-up release on a numerical basis for few dislocation numbers [3]. For release from a viscous obstacle, previous and new computations lead to a local temperature plateau occurring at the origin of pile-up release [4], in line with the physical concept of a hot spot. [1] R.W. Armstrong, C.S. Coffey, V.F. DeVost and W.L. Elban, J. Appl. Phys. 68 (1990) 979. [2] R.W. Armstrong and F.J. Zerilli, Mech. Mater. 17 (1994) 319. [3] R.W. Armstrong, Proc. Eighth Intern. Seminar: New Trends in Research of Energetic Materials, April 19- 21, 2005, Pardubice, CZ. [4] W.R. Grise, NRC/AFOSR Summer Faculty Fellowship Program, AFRL/MNME, Eglin Air Force Base, FL, 2003.

  14. Probing binding hot spots at protein–RNA recognition sites

    PubMed Central

    Barik, Amita; Nithin, Chandran; Karampudi, Naga Bhushana Rao; Mukherjee, Sunandan; Bahadur, Ranjit Prasad

    2016-01-01

    We use evolutionary conservation derived from structure alignment of polypeptide sequences along with structural and physicochemical attributes of protein–RNA interfaces to probe the binding hot spots at protein–RNA recognition sites. We find that the degree of conservation varies across the RNA binding proteins; some evolve rapidly compared to others. Additionally, irrespective of the structural class of the complexes, residues at the RNA binding sites are evolutionary better conserved than those at the solvent exposed surfaces. For recognitions involving duplex RNA, residues interacting with the major groove are better conserved than those interacting with the minor groove. We identify multi-interface residues participating simultaneously in protein–protein and protein–RNA interfaces in complexes where more than one polypeptide is involved in RNA recognition, and show that they are better conserved compared to any other RNA binding residues. We find that the residues at water preservation site are better conserved than those at hydrated or at dehydrated sites. Finally, we develop a Random Forests model using structural and physicochemical attributes for predicting binding hot spots. The model accurately predicts 80% of the instances of experimental ΔΔG values in a particular class, and provides a stepping-stone towards the engineering of protein–RNA recognition sites with desired affinity. PMID:26365245

  15. Probing binding hot spots at protein-RNA recognition sites.

    PubMed

    Barik, Amita; Nithin, Chandran; Karampudi, Naga Bhushana Rao; Mukherjee, Sunandan; Bahadur, Ranjit Prasad

    2016-01-29

    We use evolutionary conservation derived from structure alignment of polypeptide sequences along with structural and physicochemical attributes of protein-RNA interfaces to probe the binding hot spots at protein-RNA recognition sites. We find that the degree of conservation varies across the RNA binding proteins; some evolve rapidly compared to others. Additionally, irrespective of the structural class of the complexes, residues at the RNA binding sites are evolutionary better conserved than those at the solvent exposed surfaces. For recognitions involving duplex RNA, residues interacting with the major groove are better conserved than those interacting with the minor groove. We identify multi-interface residues participating simultaneously in protein-protein and protein-RNA interfaces in complexes where more than one polypeptide is involved in RNA recognition, and show that they are better conserved compared to any other RNA binding residues. We find that the residues at water preservation site are better conserved than those at hydrated or at dehydrated sites. Finally, we develop a Random Forests model using structural and physicochemical attributes for predicting binding hot spots. The model accurately predicts 80% of the instances of experimental ΔΔG values in a particular class, and provides a stepping-stone towards the engineering of protein-RNA recognition sites with desired affinity.

  16. Combined hot-spot stress procedures for tubular joints

    SciTech Connect

    Buitrayo, J.; Kahlich, J.L.; Zettlemoyer, N.

    1984-05-01

    An alternative procedure for predicting the combined hot-spot stress (CHSS) at tubular K and Y joints under combined branch loading is presented. The procedure makes use of influence factor (IF) equations developed, as a function of the joint geometry and branch loading, for various potential hot-spot locations on the branch and chord sides of the weld. The CHSS is obtained by lineraly superimposing, at a point, the effects of the axial force and bending moments acting on each branch. The resulting CHSS, therefore, reflects location, orientation and sign of each branch load contribution. Comparisons of predicted CHSS obtained via the new and other procedures to stresses from finite element analyses were made on a large sample of joints. Result show that (1) the new procedure is substantially more reliable than the other procedures studied, (2) none of the procedures consistently predicts conservative CHSS values, and (3) the overriding factor influencing the accuracy of the CHSS calculations appears to be the accuracy of the parametric equations. Although a better stress predictor can be expected to yield more reliable fatigue damage estimates, damage calculations will exhibit broad scatter due to the power function relating damage to stress. Unfortunately, further improvements in the accuracy of CHSS based on parametric equations are not likely to be easily achieved, given the large number of variables and locations that need to be considered.

  17. Drug 'hot-spots', alcohol availability and violence.

    PubMed

    Gorman, D M; Zhu, Li; Horel, Scott

    2005-11-01

    Ecological studies have shown a relationship between alcohol outlet densities and violence and between the location of crimes related to illicit drug use (so-called 'hot spots') and violence. To date, no study has compared the effects of alcohol outlets and drug hot spots on rates of violence. The present study examined this relationship in the City of Houston, Texas. An ecological study design was employed, using a sample of 439 census tracts from Houston, Texas. Neighborhood socio-structural, alcohol outlet density, drug crime density and violent crime density data were collected from archival sources and analyzed using multivariate and spatial statistics. Using ordinary least-squares analysis, the neighborhood socio-structural covariates explained about 40% of the variability in violent crime. Adding alcohol outlet density in the target census tracts explained an additional 6%, while the addition of drug crime density explained an additional 32%. In the final model, that controlled for the effects of autocorrelated error, both drug crime density in the target and adjacent census tracts remained significant predictors of violent crime, while only off-sale density in the target census tract remained significant in the model. The findings indicate that drug crime density explained a greater amount of variance in violent crime rates than the alcohol outlet density. The methodological and policy implications of these findings are discussed, along with the shortcomings of the analysis presented.

  18. Hot spot detection for indecomposable self-aligned double patterning layout

    NASA Astrophysics Data System (ADS)

    Zhang, Hongbo; Du, Yuelin; Wong, Martin D. F.; Topaloglu, Rasit O.

    2011-11-01

    Self-aligned double patterning (SADP) lithography is a novel lithography technology which has the capability to define critical dimension (CD) using one single exposure, therefore holding a great opportunity for the next generation lithography process for the overlay mitigation. However, a necessary design manufacturing co-optimization step - the non-decomposability position detection (hot spot detection) - is still immature. In this paper, targeting the hot spot detection difficulties in SADP process, we first revisit out previous ILP-based SADP decomposition algorithm and provide an extended ILP-based hot spot detection without any preconditions on the design. Then, with some simple requirement that is commonly seen in 2D random layout, we further provided a graph based hot spot detection for an efficient hot spot detection. From the Nangate standard cell library, our experiment validates the hot spot detection process and demonstrates an SADP friendly design tyle is necessary for the upcoming 14nm technology node.

  19. Hot spots and active longitudes: Organization of solar activity as a probe of the interior

    NASA Technical Reports Server (NTRS)

    Bai, Taeil; Hoeksema, J. Todd; Scherrer, Phil H.

    1995-01-01

    In order to investigate how solar activity is organized in longitude, major solar flares, large sunspot groups, and large scale photospheric magnetic field strengths were analyzed. The results of these analyses are reported. The following results are discussed: hot spots, initially recognized as areas of high concentration of major flares, are the preferred locations for the emergence of big sunspot groups; double hot spots appear in pairs that rotate at the same rate separated by about 180 deg in longitude, whereas, single hot spots have no such companions; the northern and southern hemispheres behave differently in organizing solar activity in longitude; the lifetime of hot spots range from one to several solar cycles; a hot spot is not always active throughout its lifetime, but goes through dormant periods; and hot spots with different rotational periods coexist in the same hemisphere during the same solar cycle.

  20. Cold Spots in Neonatal Incubators Are Hot Spots for Microbial Contamination▿

    PubMed Central

    de Goffau, Marcus C.; Bergman, Klasien A.; de Vries, Hendrik J.; Meessen, Nico E. L.; Degener, John E.; van Dijl, Jan Maarten; Harmsen, Hermie J. M.

    2011-01-01

    Thermal stability is essential for the survival and well-being of preterm neonates. This is achieved in neonatal incubators by raising the ambient temperature and humidity to sufficiently high levels. However, potentially pathogenic microorganisms also can thrive in such warm and humid environments. We therefore investigated whether the level of microbial contamination (i.e., the bacterial load) inside neonatal incubators can be predicted on the basis of their average temperature and relative humidity settings, paying special attention to local temperature differences. Swab samples were taken from the warmest and coldest spots found within Caleo incubators, and these were plated to determine the number of microbial CFU per location. In incubators with high average temperature (≥34°C) and relative humidity (≥60%) values, the level of microbial contamination was significantly higher at cold spots than at hot spots. This relates to the fact that the local equilibrium relative humidity at cold spots is sufficiently high to sustain microbial growth. The abundance of staphylococci, which are the main causative agents of late-onset sepsis in preterm neonates, was found to be elevated significantly in cold areas. These findings can be used to improve basic incubator hygiene. PMID:22003021

  1. Modeling Hot-Spot Contributions in Shocked High Explosives at the Mesoscale

    SciTech Connect

    Harrier, Danielle

    2015-08-12

    When looking at performance of high explosives, the defects within the explosive become very important. Plastic bonded explosives, or PBXs, contain voids of air and bonder between the particles of explosive material that aid in the ignition of the explosive. These voids collapse in high pressure shock conditions, which leads to the formation of hot spots. Hot spots are localized high temperature and high pressure regions that cause significant changes in the way the explosive material detonates. Previously hot spots have been overlooked with modeling, but now scientists are realizing their importance and new modeling systems that can accurately model hot spots are underway.

  2. Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy.

    PubMed

    Chen, Ming-Wei; You, Sizhu; Suslick, Kenneth S; Dlott, Dana D

    2014-02-01

    We have observed and characterized hot spot formation and hot-spot ignition of energetic materials (EM), where hot spots were created by ultrasonic or long-wavelength infrared (LWIR) exposure, and were detected by high-speed thermal microscopy. The microscope had 15-20 μm spatial resolution and 8.3 ms temporal resolution. LWIR was generated by a CO2 laser (tunable near 10.6 μm or 28.3 THz) and ultrasound by a 20 kHz acoustic horn. Both methods of energy input created spatially homogeneous energy fields, allowing hot spots to develop spontaneously due to the microstructure of the sample materials. We observed formation of hot spots which grew and caused the EM to ignite. The EM studied here consisted of composite solids with 1,3,5-trinitroperhydro-1,3,5-triazine crystals and polymer binders. EM simulants based on sucrose crystals in binders were also examined. The mechanisms of hot spot generation were different with LWIR and ultrasound. With LWIR, hot spots were most efficiently generated within the EM crystals at LWIR wavelengths having longer absorption depths of ∼25 μm, suggesting that hot spot generation mechanisms involved localized absorbing defects within the crystals, LWIR focusing in the crystals or LWIR interference in the crystals. With ultrasound, hot spots were primarily generated in regions of the polymer binder immediately adjacent to crystal surfaces, rather than inside the EM crystals.

  3. Multifrequency multi-qubit entanglement based on plasmonic hot spots

    NASA Astrophysics Data System (ADS)

    Ren, Jun; Wu, Tong; Zhang, Xiangdong

    2015-09-01

    The theoretical method to study strong coupling between an ensemble of quantum emitters (QEs) and surface plasmons excited by the nanoparticle cluster has been presented by using a rigorous first-principles electromagnetic Green’s tensor technique. We have demonstrated that multi-qubit entanglements for two-level QEs can be produced at different coupling resonance frequencies, when they locate in the hot spots of the metallic nanoparticle cluster. The duration of quantum beats for such an entanglement can reach two orders longer than that for the entanglement in a photonic cavity. The phenomenon originates from collective coupling resonance excitation of the cluster. At the frequency of single scattering resonance, the entanglement cannot be produced although the single QE spontaneous decay rate is very big.

  4. Multifrequency multi-qubit entanglement based on plasmonic hot spots

    PubMed Central

    Ren, Jun; Wu, Tong; Zhang, Xiangdong

    2015-01-01

    The theoretical method to study strong coupling between an ensemble of quantum emitters (QEs) and surface plasmons excited by the nanoparticle cluster has been presented by using a rigorous first-principles electromagnetic Green’s tensor technique. We have demonstrated that multi-qubit entanglements for two-level QEs can be produced at different coupling resonance frequencies, when they locate in the hot spots of the metallic nanoparticle cluster. The duration of quantum beats for such an entanglement can reach two orders longer than that for the entanglement in a photonic cavity. The phenomenon originates from collective coupling resonance excitation of the cluster. At the frequency of single scattering resonance, the entanglement cannot be produced although the single QE spontaneous decay rate is very big. PMID:26350051

  5. Predicting 'hot' and 'warm' spots for fragment binding.

    PubMed

    Rathi, Prakash Chandra; Ludlow, R Frederick; Hall, Richard John; Murray, Christopher W; Mortenson, Paul Neil; Verdonk, Marcel L

    2017-04-04

    Computational fragment mapping methods aim to predict hotspots on protein surfaces where small fragments will bind. Such methods are popular for druggability assessment as well as structure-based design. However, to date researchers developing or using such tools have had no clear way of assessing the performance of these methods. Here, we introduce the first diverse, high quality validation set for computational fragment mapping. The set contains 52 diverse examples of fragment binding 'hot' and 'warm' spots from the Protein Data Bank (PDB). Additionally, we describe PLImap, a novel protocol for fragment mapping based on the Protein-Ligand Interaction force field (PLIff). We evaluate PLImap against the new fragment mapping test set, and compare its performance to that of simple shape-based algorithms and fragment docking using GOLD. PLImap is made publicly available from https://bitbucket.org/AstexUK/pli.

  6. Deadwood as Biogeochemical `Hot Spots' in Soil and Forest Ecosystems

    NASA Astrophysics Data System (ADS)

    Stutz, K. P.; Wambsganss, J.; Lang, F.

    2016-12-01

    Forest use removes substantial quantities of woody biomass. As such, a prominent feature of managed forests is the lack of deadwood, specifically coarse woody debris (CWD), when compared to undisturbed forests. Yet the extent to which this disruption of litter cycling impacts the biogeochemistry of soil and forest ecosystems remains unclear. We sampled 32 pairs of points near deadwood and points distant from deadwood at eight Fagus sylvatica (L.) stands in SW Germany. Metabolites released from deadwood influenced soil pH, cation exchange capacity, nutrient availability, pore size distribution, and soil organic matter fractions. The extent to which deadwood influenced these soil properties depended though on site conditions such as biological activity, bedrock type, and harvesting intensity. In another, smaller study of the same design, deadwood of Abies alba (Mill.) and F. sylvatica in a mixed stand influenced soil functioning to unequal extents. This was best explained by differences in the quality of decayed lignin and other metabolites from brown-rot and white-rot. These results suggest deadwood is a transient center of biological activity where biogeochemical exchanges and cycling occurs, and as such warrants the designation as a `hot spot'. At meter and sub-meter scales, those processes contribute to aggregation, mineral weathering, and horizon differentiation - i.e., soil development. And as with other, more-studied `hot spots' such as the rhizosphere, these centers of soil development would have an oversized influence in soil and forest ecosystems both spatially and temporally. Consequently the removal (or retention) of deadwood through forest disturbances could alter the resilience and tipping points of soils and forests.

  7. Hot spots of multivariate extreme anomalies in Earth observations

    NASA Astrophysics Data System (ADS)

    Flach, M.; Sippel, S.; Bodesheim, P.; Brenning, A.; Denzler, J.; Gans, F.; Guanche, Y.; Reichstein, M.; Rodner, E.; Mahecha, M. D.

    2016-12-01

    Anomalies in Earth observations might indicate data quality issues, extremes or the change of underlying processes within a highly multivariate system. Thus, considering the multivariate constellation of variables for extreme detection yields crucial additional information over conventional univariate approaches. We highlight areas in which multivariate extreme anomalies are more likely to occur, i.e. hot spots of extremes in global atmospheric Earth observations that impact the Biosphere. In addition, we present the year of the most unusual multivariate extreme between 2001 and 2013 and show that these coincide with well known high impact extremes. Technically speaking, we account for multivariate extremes by using three sophisticated algorithms adapted from computer science applications. Namely an ensemble of the k-nearest neighbours mean distance, a kernel density estimation and an approach based on recurrences is used. However, the impact of atmosphere extremes on the Biosphere might largely depend on what is considered to be normal, i.e. the shape of the mean seasonal cycle and its inter-annual variability. We identify regions with similar mean seasonality by means of dimensionality reduction in order to estimate in each region both the `normal' variance and robust thresholds for detecting the extremes. In addition, we account for challenges like heteroscedasticity in Northern latitudes. Apart from hot spot areas, those anomalies in the atmosphere time series are of particular interest, which can only be detected by a multivariate approach but not by a simple univariate approach. Such an anomalous constellation of atmosphere variables is of interest if it impacts the Biosphere. The multivariate constellation of such an anomalous part of a time series is shown in one case study indicating that multivariate anomaly detection can provide novel insights into Earth observations.

  8. Rigorous assessment and integration of the sequence and structure based features to predict hot spots

    PubMed Central

    2011-01-01

    Background Systematic mutagenesis studies have shown that only a few interface residues termed hot spots contribute significantly to the binding free energy of protein-protein interactions. Therefore, hot spots prediction becomes increasingly important for well understanding the essence of proteins interactions and helping narrow down the search space for drug design. Currently many computational methods have been developed by proposing different features. However comparative assessment of these features and furthermore effective and accurate methods are still in pressing need. Results In this study, we first comprehensively collect the features to discriminate hot spots and non-hot spots and analyze their distributions. We find that hot spots have lower relASA and larger relative change in ASA, suggesting hot spots tend to be protected from bulk solvent. In addition, hot spots have more contacts including hydrogen bonds, salt bridges, and atomic contacts, which favor complexes formation. Interestingly, we find that conservation score and sequence entropy are not significantly different between hot spots and non-hot spots in Ab+ dataset (all complexes). While in Ab- dataset (antigen-antibody complexes are excluded), there are significant differences in two features between hot pots and non-hot spots. Secondly, we explore the predictive ability for each feature and the combinations of features by support vector machines (SVMs). The results indicate that sequence-based feature outperforms other combinations of features with reasonable accuracy, with a precision of 0.69, a recall of 0.68, an F1 score of 0.68, and an AUC of 0.68 on independent test set. Compared with other machine learning methods and two energy-based approaches, our approach achieves the best performance. Moreover, we demonstrate the applicability of our method to predict hot spots of two protein complexes. Conclusion Experimental results show that support vector machine classifiers are quite

  9. Dynamic programming-based hot spot identification approach for pedestrian crashes.

    PubMed

    Medury, Aditya; Grembek, Offer

    2016-08-01

    Network screening techniques are widely used by state agencies to identify locations with high collision concentration, also referred to as hot spots. However, most of the research in this regard has focused on identifying highway segments that are of concern to automobile collisions. In comparison, pedestrian hot spot detection has typically focused on analyzing pedestrian crashes in specific locations, such as at/near intersections, mid-blocks, and/or other crossings, as opposed to long stretches of roadway. In this context, the efficiency of the some of the widely used network screening methods has not been tested. Hence, in order to address this issue, a dynamic programming-based hot spot identification approach is proposed which provides efficient hot spot definitions for pedestrian crashes. The proposed approach is compared with the sliding window method and an intersection buffer-based approach. The results reveal that the dynamic programming method generates more hot spots with a higher number of crashes, while providing small hot spot segment lengths. In comparison, the sliding window method is shown to suffer from shortcomings due to a first-come-first-serve approach vis-à-vis hot spot identification and a fixed hot spot window length assumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. PRDM9 variation strongly influences recombination hot-spot activity and meiotic instability in humans.

    PubMed

    Berg, Ingrid L; Neumann, Rita; Lam, Kwan-Wood G; Sarbajna, Shriparna; Odenthal-Hesse, Linda; May, Celia A; Jeffreys, Alec J

    2010-10-01

    PRDM9 has recently been identified as a likely trans regulator of meiotic recombination hot spots in humans and mice. PRDM9 contains a zinc finger array that, in humans, can recognize a short sequence motif associated with hot spots, with binding to this motif possibly triggering hot-spot activity via chromatin remodeling. We now report that human genetic variation at the PRDM9 locus has a strong effect on sperm hot-spot activity, even at hot spots lacking the sequence motif. Subtle changes within the zinc finger array can create hot-spot nonactivating or enhancing variants and can even trigger the appearance of a new hot spot, suggesting that PRDM9 is a major global regulator of hot spots in humans. Variation at the PRDM9 locus also influences aspects of genome instability-specifically, a megabase-scale rearrangement underlying two genomic disorders as well as minisatellite instability-implicating PRDM9 as a risk factor for some pathological genome rearrangements.

  11. A feature-based approach to modeling protein-protein interaction hot spots.

    PubMed

    Cho, Kyu-il; Kim, Dongsup; Lee, Doheon

    2009-05-01

    Identifying features that effectively represent the energetic contribution of an individual interface residue to the interactions between proteins remains problematic. Here, we present several new features and show that they are more effective than conventional features. By combining the proposed features with conventional features, we develop a predictive model for interaction hot spots. Initially, 54 multifaceted features, composed of different levels of information including structure, sequence and molecular interaction information, are quantified. Then, to identify the best subset of features for predicting hot spots, feature selection is performed using a decision tree. Based on the selected features, a predictive model for hot spots is created using support vector machine (SVM) and tested on an independent test set. Our model shows better overall predictive accuracy than previous methods such as the alanine scanning methods Robetta and FOLDEF, and the knowledge-based method KFC. Subsequent analysis yields several findings about hot spots. As expected, hot spots have a larger relative surface area burial and are more hydrophobic than other residues. Unexpectedly, however, residue conservation displays a rather complicated tendency depending on the types of protein complexes, indicating that this feature is not good for identifying hot spots. Of the selected features, the weighted atomic packing density, relative surface area burial and weighted hydrophobicity are the top 3, with the weighted atomic packing density proving to be the most effective feature for predicting hot spots. Notably, we find that hot spots are closely related to pi-related interactions, especially pi . . . pi interactions.

  12. Advantages of Fast Ignition Scenarios with Two Hot Spots for Space Propulsion Systems

    NASA Astrophysics Data System (ADS)

    Shmatov, M. L.

    The use of the fast ignition scenarios with the attempts to create two hot spots in one blob of the compressed thermonuclear fuel or, briefly, scenarios with two hot spots in space propulsion systems is proposed. The model, predicting that for such scenarios the probability pf of failure of ignition of thermonuclear microexplosion can be significantly less than that for the similar scenarios with the attempts to create one hot spot in one blob of the compressed fuel, is presented. For space propulsion systems consuming a relatively large amount of propellant, a decrease in pf due to the choice of the scenario with two hot spots can result in large, for example, two-fold, increase in the payload mass. Other advantages of the scenarios with two hot spots and some problems related to them are considered.

  13. Experimental Study of Ignition by Hot Spot in Internal Combustion Engines

    NASA Technical Reports Server (NTRS)

    Serruys, Max

    1938-01-01

    In order to carry out the contemplated study, it was first necessary to provide hot spots in the combustion chamber, which could be measured and whose temperature could be changed. It seemed difficult to realize both conditions working solely on the temperature of the cooling water in a way so as to produce hot spots on the cylinder wall capable of provoking autoignition. Moreover, in the majority of practical cases, autoignition is produced by the spark plug, one of the least cooled parts in the engine. The first procedure therefore did not resemble that which most generally occurs in actual engine operation. All of these considerations caused us to reproduce similar hot spots at the spark plugs. The hot spots produced were of two kinds and designated with the name of thermo-electric spark plug and of metallic hot spot.

  14. Hot spots on Io: Initial results from Galileo's near infrared mapping spectrometer

    USGS Publications Warehouse

    Lopes-Gautier, R.; Davies, A.G.; Carlson, R.; Smythe, W.; Kamp, L.; Soderblom, L.; Leader, F.E.; Mehlman, R.

    1997-01-01

    The Near-Infrared Mapping Spectrometer on Galileo has monitored the volcanic activity on Io since June 28, 1996. This paper presents preliminary analysis of NIMS thermal data for the first four orbits of the Galileo mission. NIMS has detected 18 new hot spots and 12 others which were previously known to be active. The distribution of the hot spots on Io's surface may not be random, as hot spots surround the two bright, SO2-rich regions of Bosphorus Regio and Colchis Regio. Most hot spots seem to be persistently active from orbit to orbit and 10 of those detected were active in 1979 during the Voyager encounters. We report the distribution of hot spot temperatures and find that they are consistent with silicate volcanism. Copyright 1997 by the American Geophysical Union.

  15. Live-Cell Pyrophosphate Imaging by in Situ Hot-Spot Generation.

    PubMed

    Li, Mingmin; Li, Jin; Di, Huixia; Liu, Huiqiao; Liu, Dingbin

    2017-03-21

    Controlling the electromagnetic hot-spot generation is essential for surface-enhanced Raman scattering (SERS) assays. Current hot-spot-based SERS assays have been extensively studied in solutions or on substrates. However, probing biospecies by controlling the hot-spot assembly in living systems has not been demonstrated thus far. Herein, we report a background-free SERS probe for imaging pyrophosphate (PPi), a biochemically significant anion, in living cells. Intracellular PPi is able to induce the nanoparticle dimerization, thus creating an intense electromagnetic hot spot and dramatically enhancing the signal of the Raman reporters residing in the hot spot. More impressively, the reporter we used in this study provides a strong and sharp single peak in the cellular Raman-silent region (1800-2800 cm(-1)), thus eliminating the possible background interference. This strategy could be readily extended to detect other biomarkers by only replacing the recognition ligands.

  16. Spatial confinement of electromagnetic hot and cold spots in gold nanocubes.

    PubMed

    Haggui, Mohamed; Dridi, Montacer; Plain, Jérôme; Marguet, Sylvie; Perez, Henri; Schatz, George C; Wiederrecht, Gary P; Gray, Stephen K; Bachelot, Renaud

    2012-02-28

    We report a near-field imaging study of colloidal gold nanocubes. This is accomplished through a photochemical imaging method in which molecular displacements are vectorial in nature, enabling sensitivity to the polarization of the optical near-field of the nanocubes. We analyze the confinement of both electromagnetic hot and "cold" spots with a resolution of λ/35 and emphasize the particularly high spatial confinement of cold spots. The concept of a cold spot complements the well-known electromagnetic hot spot but can have significant advantages. The application of the ultraconfined cold spots to high resolution imaging and spectroscopy is discussed.

  17. Hot-spot mix in ignition-scale implosions on the NIF [Hot-spot mix in ignition-scale implosions on the National Ignition Facility (NIF)

    DOE PAGES

    Regan, S. P.; Epstein, R.; Hammel, B. A.; ...

    2012-03-30

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding 2 a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraummore » x-ray drive. Richtmyer–Meshkov and Rayleigh–Taylor hydrodynamic instabilities seeded by high-mode (50 < t < 200) ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium–hydrogen–deuterium (THD) and DT cryogenic targets and gas-filled plastic shell capsules, which replace the THD layer with a massequivalent CH layer, was examined. The inferred amount of hot-spot mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code, is typically below the 75 ng allowance for hot-spot mix. Furthermore, predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.« less

  18. Hot-spot mix in ignition-scale implosions on the NIF [Hot-spot mix in ignition-scale implosions on the National Ignition Facility (NIF)

    SciTech Connect

    Regan, S. P.; Epstein, R.; Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Doeppner, T.; Edwards, M. J.; Farley, D. R.; Glenn, S.; Glenzer, S. H.; Golovkin, I. E.; Haan, S. W.; Hamza, A.; Hicks, D. G.; Izumi, N.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; Ma, T.; MacFarlane, J. J.; Mancini, R. C.; McCrory, R. L.; Meezan, N. B.; Meyerhofer, D. D.; Nikroo, A.; Peterson, K. J.; Sangster, T. C.; Springer, P.; Town, R. P. J.

    2012-03-30

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding 2 a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive. Richtmyer–Meshkov and Rayleigh–Taylor hydrodynamic instabilities seeded by high-mode (50 < t < 200) ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium–hydrogen–deuterium (THD) and DT cryogenic targets and gas-filled plastic shell capsules, which replace the THD layer with a massequivalent CH layer, was examined. The inferred amount of hot-spot mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code, is typically below the 75 ng allowance for hot-spot mix. Furthermore, predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.

  19. Methodology and software to detect viral integration site hot-spots

    PubMed Central

    2011-01-01

    Background Modern gene therapy methods have limited control over where a therapeutic viral vector inserts into the host genome. Vector integration can activate local gene expression, which can cause cancer if the vector inserts near an oncogene. Viral integration hot-spots or 'common insertion sites' (CIS) are scrutinized to evaluate and predict patient safety. CIS are typically defined by a minimum density of insertions (such as 2-4 within a 30-100 kb region), which unfortunately depends on the total number of observed VIS. This is problematic for comparing hot-spot distributions across data sets and patients, where the VIS numbers may vary. Results We develop two new methods for defining hot-spots that are relatively independent of data set size. Both methods operate on distributions of VIS across consecutive 1 Mb 'bins' of the genome. The first method 'z-threshold' tallies the number of VIS per bin, converts these counts to z-scores, and applies a threshold to define high density bins. The second method 'BCP' applies a Bayesian change-point model to the z-scores to define hot-spots. The novel hot-spot methods are compared with a conventional CIS method using simulated data sets and data sets from five published human studies, including the X-linked ALD (adrenoleukodystrophy), CGD (chronic granulomatous disease) and SCID-X1 (X-linked severe combined immunodeficiency) trials. The BCP analysis of the human X-linked ALD data for two patients separately (774 and 1627 VIS) and combined (2401 VIS) resulted in 5-6 hot-spots covering 0.17-0.251% of the genome and containing 5.56-7.74% of the total VIS. In comparison, the CIS analysis resulted in 12-110 hot-spots covering 0.018-0.246% of the genome and containing 5.81-22.7% of the VIS, corresponding to a greater number of hot-spots as the data set size increased. Our hot-spot methods enable one to evaluate the extent of VIS clustering, and formally compare data sets in terms of hot-spot overlap. Finally, we show that the

  20. Identification of biogeochemical hot spots using time-lapse hydrogeophysics

    NASA Astrophysics Data System (ADS)

    Franz, T. E.; Loecke, T.; Burgin, A.

    2016-12-01

    The identification and monitoring of biogeochemical hot spots and hot moments is difficult using point based sampling techniques and sensors. Without proper monitoring and accounting of water, energy, and trace gas fluxes it is difficult to assess the environmental footprint of land management practices. One key limitation is optimal placement of sensors/chambers that adequately capture the point scale fluxes and thus a reasonable integration to landscape scale flux. In this work we present time-lapse hydrogeophysical imaging at an old agricultural field converted into a wetland mitigation bank near Dayton, Ohio. While the wetland was previously instrumented with a network of soil sensors and surface chambers to capture a suite of state variables and fluxes, we hypothesize that time-lapse hydrogeophysical imaging is an underutilized and critical reconnaissance tool for effective network design and landscape scaling. Here we combine the time-lapse hydrogeophysical imagery with the multivariate statistical technique of Empirical Orthogonal Functions (EOF) in order to isolate the spatial and temporal components of the imagery. Comparisons of soil core information (e.g. soil texture, soil carbon) from around the study site and organized within like spatial zones reveal statistically different mean values of soil properties. Moreover, the like spatial zones can be used to identify a finite number of future sampling locations, evaluation of the placement of existing sensors/chambers, upscale/downscale observations, all of which are desirable techniques for commercial use in precision agriculture. Finally, we note that combining the EOF analysis with continuous monitoring from point sensors or remote sensing products may provide a robust statistical framework for scaling observations through time as well as provide appropriate datasets for use in landscape biogeochemical models.

  1. Concentration of Strontium-90 at Selected Hot Spots in Japan

    PubMed Central

    Steinhauser, Georg; Schauer, Viktoria; Shozugawa, Katsumi

    2013-01-01

    This study is dedicated to the environmental monitoring of radionuclides released in the course of the Fukushima nuclear accident. The activity concentrations of β− -emitting 90Sr and β−/γ-emitting 134Cs and 137Cs from several hot spots in Japan were determined in soil and vegetation samples. The 90Sr contamination levels of the samples were relatively low and did not exceed the Bq⋅g−1 range. They were up four orders of magnitude lower than the respective 137Cs levels. This study, therefore, experimentally confirms previous predictions indicating a low release of 90Sr from the Fukushima reactors, due to its low volatility. The radiocesium contamination could be clearly attributed to the Fukushima nuclear accident via its activity ratio fingerprint (134Cs/137Cs). Although the correlation between 90Sr and 137Cs is relatively weak, the data set suggests an intrinsic coexistence of both radionuclides in the contaminations caused by the Fukushima nuclear accident. This observation is of great importance not only for remediation campaigns but also for the current food monitoring campaigns, which currently rely on the assumption that the activity concentrations of β−-emitting 90Sr (which is relatively laborious to determine) is not higher than 10% of the level of γ-emitting 137Cs (which can be measured quickly). This assumption could be confirmed for the samples investigated herein. PMID:23505440

  2. On the difficulty to delimit disease risk hot spots

    NASA Astrophysics Data System (ADS)

    Charras-Garrido, M.; Azizi, L.; Forbes, F.; Doyle, S.; Peyrard, N.; Abrial, D.

    2013-06-01

    Representing the health state of a region is a helpful tool to highlight spatial heterogeneity and localize high risk areas. For ease of interpretation and to determine where to apply control procedures, we need to clearly identify and delineate homogeneous regions in terms of disease risk, and in particular disease risk hot spots. However, even if practical purposes require the delineation of different risk classes, such a classification does not correspond to a reality and is thus difficult to estimate. Working with grouped data, a first natural choice is to apply disease mapping models. We apply a usual disease mapping model, producing continuous estimations of the risks that requires a post-processing classification step to obtain clearly delimited risk zones. We also apply a risk partition model that build a classification of the risk levels in a one step procedure. Working with point data, we will focus on the scan statistic clustering method. We illustrate our article with a real example concerning the bovin spongiform encephalopathy (BSE) an animal disease whose zones at risk are well known by the epidemiologists. We show that in this difficult case of a rare disease and a very heterogeneous population, the different methods provide risk zones that are globally coherent. But, related to the dichotomy between the need and the reality, the exact delimitation of the risk zones, as well as the corresponding estimated risks are quite different.

  3. Wafer hot spot identification through advanced photomask characterization techniques

    NASA Astrophysics Data System (ADS)

    Choi, Yohan; Green, Michael; McMurran, Jeff; Ham, Young; Lin, Howard; Lan, Andy; Yang, Richer; Lung, Mike

    2016-10-01

    As device manufacturers progress through advanced technology nodes, limitations in standard 1-dimensional (1D) mask Critical Dimension (CD) metrics are becoming apparent. Historically, 1D metrics such as Mean to Target (MTT) and CD Uniformity (CDU) have been adequate for end users to evaluate and predict the mask impact on the wafer process. However, the wafer lithographer's process margin is shrinking at advanced nodes to a point that the classical mask CD metrics are no longer adequate to gauge the mask contribution to wafer process error. For example, wafer CDU error at advanced nodes is impacted by mask factors such as 3-dimensional (3D) effects and mask pattern fidelity on subresolution assist features (SRAFs) used in Optical Proximity Correction (OPC) models of ever-increasing complexity. These items are not quantifiable with the 1D metrology techniques of today. Likewise, the mask maker needs advanced characterization methods in order to optimize the mask process to meet the wafer lithographer's needs. These advanced characterization metrics are what is needed to harmonize mask and wafer processes for enhanced wafer hot spot analysis. In this paper, we study advanced mask pattern characterization techniques and their correlation with modeled wafer performance.

  4. Hot spot liver scan in focal nodular hyperplasia

    SciTech Connect

    Piers, D.A.; Houthoff, H.J.; Krom, R.A.F.; Schuur, K.H.; Sikkens, H.; Weits, J.

    1980-12-01

    In scintigraphy of the liver with radiocolloid, space-occupying lesions generally are visualized as regions of decreased accumulation of radioactivity. Rarely focal areas of increased activity are depicted; most are related to altered vascular dynamics in the liver secondary to obstruction of the superior or inferior vena cava or the hepatic veins. There are reports of single cases of focally increased activity due to a hepatic hemangioma, hepatic venoocclusive disease, herniation of a part of the liver, and a liver hot spot found after radiocolloid injection via a malpositioned central venous catheter in one of the hepatic vein branches. In patients with focal nodular hyperplasia, liver scans with solitary defects as well as normal patterns are found. In some cases, increased uptake of colloid in the lesion has been documented. Pasquier and Dorta reported a patient with a palpable mass in the left liver lobe with increased accumulation of radioactivity on the radiocolloid liver scan. The histologic diagnosis was hamartoma, but reviewing the description and considering the confusion in the past concerning the nomenclature, this case is suggestive of focal nodular hyperplasia. We report a patient with focal nodular hyperplasia who had increased radiocolloid uptake in the lesion. The radionuclide studies are compared with angiography, sonography, and computed tomography. An explanation for the localized increased colloid accumulation based on histologic findings is suggested.

  5. Magmatic effects of the Cobb hot spot on the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Chadwick, John; Perfit, Michael; Ridley, Ian; Jonasson, Ian; Kamenov, George; Chadwick, William; Embley, Robert; Le Roux, Petrus; Smith, Matthew

    2005-03-01

    The interaction of the Juan de Fuca Ridge with the Cobb hot spot has had a considerable influence on the magmatism of the Axial Segment of the ridge, the second-order segment that overlies the hot spot. In addition to the construction of the large volcanic edifice of Axial Seamount, the Axial Segment has shallow bathymetry and a prevalence of constructional volcanic features along its 100-km length, suggesting that hot spot-derived magmas supplement and oversupply the ridge. Lavas are generally more primitive at Axial Seamount and more evolved in the Axial Segment rift zones, suggesting that fractional crystallization is enhanced with increasing distance from the hot spot because of a reduced magma supply and more rapid cooling. Although the Cobb hot spot is not an isotopically enriched plume, it produces lavas with some distinct geochemical characteristics relative to normal mid-ocean ridge basalt, such as enrichments in alkalis and highly incompatible trace elements, that can be used as tracers to identify the presence and prevalence of the hot spot influence along the ridge. These characteristics are most prominent at Axial Seamount and decline in gradients along the Axial Segment. The physical model that can best explain the geochemical observations is a scenario in which hot spot and mid-ocean ridge basalt (MORB) magmas mix to varying degrees, with the proportions controlled by the depth to the MORB source. Modeling of two-component mixing suggests that MORB is the dominant component in most Axial Segment basalts.

  6. Hot spot generation in energetic materials created by long-wavelength infrared radiation

    SciTech Connect

    Chen, Ming-Wei; You, Sizhu; Suslick, Kenneth S.; Dlott, Dana D.

    2014-02-10

    Hot spots produced by long-wavelength infrared (LWIR) radiation in an energetic material, crystalline RDX (1,3,5-trinitroperhydro-1,3,5-triazine), were studied by thermal-imaging microscopy. The LWIR source was a CO{sub 2} laser operating in the 28-30 THz range. Hot spot generation was studied using relatively low intensity (∼100 W cm{sup −2}), long-duration (450 ms) LWIR pulses. The hot spots could be produced repeatedly in individual RDX crystals, to investigate the fundamental mechanisms of hot spot generation by LWIR, since the peak hot-spot temperatures were kept to ∼30 K above ambient. Hot spots were generated preferentially beneath RDX crystal planes making oblique angles with the LWIR beam. Surprisingly, hot spots were more prominent when the LWIR wavelength was tuned to be weakly absorbed (absorption depth ∼30 μm) than when the LWIR wavelength was strongly absorbed (absorption depth ∼5 μm). This unexpected effect was explained using a model that accounts for LWIR refraction and RDX thermal conduction. The weakly absorbed LWIR is slightly focused underneath the oblique crystal planes, and it penetrates the RDX crystals more deeply, increasing the likelihood of irradiating RDX defect inclusions that are able to strongly absorb or internally focus the LWIR beam.

  7. The evolutionary turnover of recombination hot spots contributes to speciation in mice

    PubMed Central

    Smagulova, Fatima; Brick, Kevin; Pu, Yongmei; Camerini-Otero, R. Daniel; Petukhova, Galina V.

    2016-01-01

    Meiotic recombination is required for the segregation of homologous chromosomes and is essential for fertility. In most mammals, the DNA double-strand breaks (DSBs) that initiate meiotic recombination are directed to a subset of genomic loci (hot spots) by sequence-specific binding of the PRDM9 protein. Rapid evolution of the DNA-binding specificity of PRDM9 and gradual erosion of PRDM9-binding sites by gene conversion will alter the recombination landscape over time. To better understand the evolutionary turnover of recombination hot spots and its consequences, we mapped DSB hot spots in four major subspecies of Mus musculus with different Prdm9 alleles and in their F1 hybrids. We found that hot spot erosion governs the preferential usage of some Prdm9 alleles over others in hybrid mice and increases sequence diversity specifically at hot spots that become active in the hybrids. As crossovers are disfavored at such hot spots, we propose that sequence divergence generated by hot spot turnover may create an impediment for recombination in hybrids, potentially leading to reduced fertility and, eventually, speciation. PMID:26833728

  8. The evolutionary turnover of recombination hot spots contributes to speciation in mice.

    PubMed

    Smagulova, Fatima; Brick, Kevin; Pu, Yongmei; Camerini-Otero, R Daniel; Petukhova, Galina V

    2016-02-01

    Meiotic recombination is required for the segregation of homologous chromosomes and is essential for fertility. In most mammals, the DNA double-strand breaks (DSBs) that initiate meiotic recombination are directed to a subset of genomic loci (hot spots) by sequence-specific binding of the PRDM9 protein. Rapid evolution of the DNA-binding specificity of PRDM9 and gradual erosion of PRDM9-binding sites by gene conversion will alter the recombination landscape over time. To better understand the evolutionary turnover of recombination hot spots and its consequences, we mapped DSB hot spots in four major subspecies of Mus musculus with different Prdm9 alleles and in their F1 hybrids. We found that hot spot erosion governs the preferential usage of some Prdm9 alleles over others in hybrid mice and increases sequence diversity specifically at hot spots that become active in the hybrids. As crossovers are disfavored at such hot spots, we propose that sequence divergence generated by hot spot turnover may create an impediment for recombination in hybrids, potentially leading to reduced fertility and, eventually, speciation.

  9. Potential Air Toxics Hot Spots in Truck Terminals and Cabs

    PubMed Central

    Smith, Thomas J.; Davis, Mary E.; Hart, Jaime E.; Blicharz, Andrew; Laden, Francine; Garshick, Eric

    2016-01-01

    INTRODUCTION Hot spots are areas where concentrations of one or more air toxics — organic vapors or particulate matter (PM) — are expected to be elevated. The U.S. Environmental Protection Agency’s (EPA*) screening values for air toxics were used in our definition of hot spots. According to the EPA, a screening value “is used to indicate a concentration of a chemical in the air to which a person could be continually exposed for a lifetime … and which would be unlikely to result in a deleterious effect (either cancer or noncancer health effects)” (U.S. EPA 2006). Our characterization of volatile organic compounds (VOCs; namely 18 hydrocarbons, methyl tert-butyl ether [MTBE], acetone, and aldehydes) was added onto our ongoing National Cancer Institute–funded study of lung cancer and particulate pollutant concentrations (PM with an aerodynamic diameter ≤ 2.5 µm [PM2.5], elemental carbon [EC], and organic carbon [OC]) and source apportionment of the U.S. trucking industry. We focused on three possible hot spots within the trucking terminals: upwind background areas affected by nearby industrial parks; downwind areas affected by upwind and terminal sources; and the loading docks and mechanic shops within terminal as well as the interior of cabs of trucks being driven on city, suburban, and rural streets and on highways. METHODS In Phase 1 of our study, 15 truck terminals across the United States were each visited for five consecutive days. During these site visits, sorbent tubes were used to collect 12-hour integrated samples of hydrocarbons and aldehydes from upwind and downwind fence-line locations as well as inside truck cabs. Meteorologic data and extensive site information were collected with each sample. In Phase 2, repeat visits to six terminals were conducted to test the stability of concentrations across time and judge the representativeness of our previous measurements. During the repeat site visits, the sampling procedure was expanded to

  10. Potential air toxics hot spots in truck terminals and cabs.

    PubMed

    Smith, Thomas J; Davis, Mary E; Hart, Jaime E; Blicharz, Andrew; Laden, Francine; Garshick, Eric

    2012-12-01

    Hot spots are areas where concentrations of one or more air toxics--organic vapors or particulate matter (PM)--are expected to be elevated. The U.S. Environmental Protection Agency's (EPA*) screening values for air toxics were used in our definition of hot spots. According to the EPA, a screening value "is used to indicate a concentration of a chemical in the air to which a person could be continually exposed for a lifetime ... and which would be unlikely to result in a deleterious effect (either cancer or noncancer health effects)" (U.S. EPA 2006). Our characterization of volatile organic compounds (VOCs; namely 18 hydrocarbons, methyl tert-butyl ether [MTBE], acetone, and aldehydes) was added onto our ongoing National Cancer Institute-funded study of lung cancer and particulate pollutant concentrations (PM with an aerodynamic diameter < or = 2.5 microm [PM2.5], elemental carbon [EC], and organic carbon [OC]) and source apportionment of the U.S. trucking industry. We focused on three possible hot spots within the trucking terminals: upwind background areas affected by nearby industrial parks; downwind areas affected by upwind and terminal sources; and the loading docks and mechanic shops within terminal as well as the interior of cabs of trucks being driven on city, suburban, and rural streets and on highways. In Phase 1 of our study, 15 truck terminals across the United States were each visited for five consecutive days. During these site visits, sorbent tubes were used to collect 12-hour integrated samples of hydrocarbons and aldehydes from upwind and downwind fence-line locations as well as inside truck cabs. Meteorologic data and extensive site information were collected with each sample. In Phase 2, repeat visits to six terminals were conducted to test the stability of concentrations across time and judge the representativeness of our previous measurements. During the repeat site visits, the sampling procedure was expanded to include real-time sampling for

  11. Hot spot detection for breast cancer in Ki-67 stained slides: image dependent filtering approach

    NASA Astrophysics Data System (ADS)

    Niazi, M. Khalid Khan; Downs-Kelly, Erinn; Gurcan, Metin N.

    2014-03-01

    We present a new method to detect hot spots from breast cancer slides stained for Ki67 expression. It is common practice to use centroid of a nucleus as a surrogate representation of a cell. This often requires the detection of individual nuclei. Once all the nuclei are detected, the hot spots are detected by clustering the centroids. For large size images, nuclei detection is computationally demanding. Instead of detecting the individual nuclei and treating hot spot detection as a clustering problem, we considered hot spot detection as an image filtering problem where positively stained pixels are used to detect hot spots in breast cancer images. The method first segments the Ki-67 positive pixels using the visually meaningful segmentation (VMS) method that we developed earlier. Then, it automatically generates an image dependent filter to generate a density map from the segmented image. The smoothness of the density image simplifies the detection of local maxima. The number of local maxima directly corresponds to the number of hot spots in the breast cancer image. The method was tested on 23 different regions of interest images extracted from 10 different breast cancer slides stained with Ki67. To determine the intra-reader variability, each image was annotated twice for hot spots by a boardcertified pathologist with a two-week interval in between her two readings. A computer-generated hot spot region was considered a true-positive if it agrees with either one of the two annotation sets provided by the pathologist. While the intra-reader variability was 57%, our proposed method can correctly detect hot spots with 81% precision.

  12. Uranium Bioreduction Rates across Scales: Biogeochemical Hot Moments and Hot Spots during a Biostimulation Experiment at Rifle, Colorado

    SciTech Connect

    Bao, Chen; Wu, Hongfei; Li, Li; Newcomer, Darrell R.; Long, Philip E.; Williams, Kenneth H.

    2014-09-02

    We aim to understand the scale-dependent evolution of uranium bioreduction during a field experiment at a former uranium mill site near Rifle, Colorado. Acetate was injected to stimulate Fe-reducing bacteria (FeRB) and to immobilize aqueous U(VI) to insoluble U(IV). Bicarbonate was coinjected in half of the domain to mobilize sorbed U(VI). We used reactive transport modeling to integrate hydraulic and geochemical data and to quantify rates at the grid block (0.25 m) and experimental field scale (tens of meters). Although local rates varied by orders of magnitude in conjunction with biostimulation fronts propagating downstream, field-scale rates were dominated by those orders of magnitude higher rates at a few selected hot spots where Fe(III), U(VI), and FeRB were at their maxima in the vicinity of the injection wells. At particular locations, the hot moments with maximum rates negatively corresponded to their distance from the injection wells. Although bicarbonate injection enhanced local rates near the injection wells by a maximum of 39.4%, its effect at the field scale was limited to a maximum of 10.0%. We propose a rate-versus-measurement-length relationship (log R' = -0.63

  13. Uranium bioreduction rates across scales: biogeochemical hot moments and hot spots during a biostimulation experiment at Rifle, Colorado.

    PubMed

    Bao, Chen; Wu, Hongfei; Li, Li; Newcomer, Darrell; Long, Philip E; Williams, Kenneth H

    2014-09-02

    We aim to understand the scale-dependent evolution of uranium bioreduction during a field experiment at a former uranium mill site near Rifle, Colorado. Acetate was injected to stimulate Fe-reducing bacteria (FeRB) and to immobilize aqueous U(VI) to insoluble U(IV). Bicarbonate was coinjected in half of the domain to mobilize sorbed U(VI). We used reactive transport modeling to integrate hydraulic and geochemical data and to quantify rates at the grid block (0.25 m) and experimental field scale (tens of meters). Although local rates varied by orders of magnitude in conjunction with biostimulation fronts propagating downstream, field-scale rates were dominated by those orders of magnitude higher rates at a few selected hot spots where Fe(III), U(VI), and FeRB were at their maxima in the vicinity of the injection wells. At particular locations, the hot moments with maximum rates negatively corresponded to their distance from the injection wells. Although bicarbonate injection enhanced local rates near the injection wells by a maximum of 39.4%, its effect at the field scale was limited to a maximum of 10.0%. We propose a rate-versus-measurement-length relationship (log R' = -0.63 log L - 2.20, with R' in μmol/mg cell protein/day and L in meters) for orders-of-magnitude estimation of uranium bioreduction rates across scales.

  14. Calculation of TIR Canopy Hot Spot and Implications for Earth Radiation Budget

    NASA Technical Reports Server (NTRS)

    Smith, J. A.; Ballard, J. R., Jr.

    2000-01-01

    Using a 3-D model for thermal infrared exitance and the Lowtran 7 atmospheric radiative transfer model, we compute the variation in brightness temperature with view direction and, in particular, the canopy thermal hot spot. We then perform a sensitivity analysis of surface energy balance components for a nominal case using a simple SVAT model given the uncertainty in canopy temperature arising from the thermal hot spot effect. Canopy thermal hot spot variations of two degrees C lead to differences of plus or minus 24% in the midday available energy.

  15. Features of surface enhanced Raman scattering in the systems with «hot spots»

    NASA Astrophysics Data System (ADS)

    Solovyeva, E. V.; Khazieva, D. A.; Denisova, A. S.

    2016-12-01

    In this work we demonstrate the features of SERS on the substrates with «hot spots» on the example of system «diaminostilbene - colloidal silver». We found that «hot spots» forming on aggregated nanoparticles exist on the metal substrates only at low concentration of ligand. This effect caused by the gradual filling of first monolayer by adsorbate molecules. Significantly higher enhancement factor is obtained for substrates with «hot spots», for which the participation of resonance processes in the formation of SERS signal is revealed also.

  16. Studies of Hot Spots in Imploding Wire Arrays at 1 MA on COBRA

    SciTech Connect

    Pikuz, Sergey A.; Shelkovenko, Tatiana A.; McBride, Ryan D.; Hammer, David A.

    2009-01-21

    We present recent results from hot spot investigations in imploding Al wire array z-pinches on the COBRA generator at Cornell University using x-ray diagnostics. Measurements of the temporal and spatial distribution of hot spots in stagnating plasmas by an x-ray streak-camera are included. Experiments show that hot spots have nanosecond lifetime and appear randomly along the array axis after plasma stagnation in secondary pinches in 8 mm diameter and during plasma stagnation in the arrays with 4 mm diameter.

  17. New 40Ar/39Ar age progression for the Louisville hot spot trail and implications for inter-hot spot motion

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Gowen, Molly D.; Colwell, Lauren E.; Gee, Jeffrey S.; Lonsdale, Peter F.; Mahoney, John J.; Duncan, Robert A.

    2011-12-01

    In this study we present 42 new 40Ar/39Ar incremental heating age determinations that contribute to an updated age progression for the Louisville seamount trail. Louisville is the South Pacific counterpart to the Hawaiian-Emperor seamount trail, both trails representing intraplate volcanism over the same time interval (˜80 Ma to present) and being examples of primary hot spot lineaments. Our data provide evidence for an age-progressive trend from 71 to 21 Ma. Assuming fixed hot spots, this makes possible a direct comparison to the Hawaiian-Emperor age progression and the most recent absolute plate motion (APM) model (WK08G) of Wessel and Kroenke (2008). We observe that for the Louisville seamount trail the measured ages are systematically older relative to both the WK08G model predictions and Hawaiian seamount ages, with offsets ranging up to 6 Myr. Taking into account the uncertainty about the duration of eruption and magmatic succession at individual Louisville volcanoes, these age offsets should be considered minimum estimates, as our sampling probably tended to recover the youngest lava flows. These large deviations point to either a contribution of inter-hot spot motion between the Louisville and Hawaiian hot spots or to a more easterly location of the Louisville hot spot than the one inferred in the WK08G model. Both scenarios are investigated in this paper, whereby the more eastern hot spot location (52.0°S, 134.5°W versus 52.4°S, 137.2°W) reduces the average age offset, but still results in a relatively large maximum offset of 3.7 Myr. When comparing the new ages to the APM models (S04P, S04G) by Steinberger et al. (2004) that attempt to compensate for the motion of hot spots in the Pacific (Hawaii) or globally (Hawaii, Louisville, Reunion and Walvis), the measured and predicted ages are more in agreement, showing only a maximum offset of 2.3 Myr with respect to the S04G model. At face value these more advanced APM models, which consider both plate and

  18. Ring of nine Gamma Ray Burst overlap with the hot spot of my hypothesis

    NASA Astrophysics Data System (ADS)

    Cao, Dayong

    2016-03-01

    During 2004 to 2014, a symmetry axis and a cold spot (a structure of one billion light years across) of CMB were observed, and I supposed there is a hot spot, and there is a symmetry between the cold spot and the hot spot of CMB. http://www.dailymail.co.uk/sciencetech/article-2430415 http://meetings.aps.org/link/BAPS.2014.MAR.Y33.9 In 2015, a Ring of Nine Gamma Ray Burst (a structure of FIVE BILLION light years across) which is a part of structure of double helix and overlap with the hot spot was observed. http://www.dailymail.co.uk/sciencetech/article-3185193 The Ring of Nine Gamma Ray Burst could be explained by the hot spot. There is a balance systemic model with structure of double helix of the flat universe between cold spot and hot spot-a balance between stellar matter and dark massenergy (include dark matter and dark energy). The model can explain of the Hubble's redshift. There is a larger dark hole instead of the huge black hole of the center of the Milky Way galaxy, and a dark hole builds up a balance system with sun. This model should explain of the seasonal Extinctions. http://meetings.aps.org/link/BAPS.2015.APR.H14.8

  19. Prediction of protein interaction hot spots using rough set-based multiple criteria linear programming.

    PubMed

    Chen, Ruoying; Zhang, Zhiwang; Wu, Di; Zhang, Peng; Zhang, Xinyang; Wang, Yong; Shi, Yong

    2011-01-21

    Protein-protein interactions are fundamentally important in many biological processes and it is in pressing need to understand the principles of protein-protein interactions. Mutagenesis studies have found that only a small fraction of surface residues, known as hot spots, are responsible for the physical binding in protein complexes. However, revealing hot spots by mutagenesis experiments are usually time consuming and expensive. In order to complement the experimental efforts, we propose a new computational approach in this paper to predict hot spots. Our method, Rough Set-based Multiple Criteria Linear Programming (RS-MCLP), integrates rough sets theory and multiple criteria linear programming to choose dominant features and computationally predict hot spots. Our approach is benchmarked by a dataset of 904 alanine-mutated residues and the results show that our RS-MCLP method performs better than other methods, e.g., MCLP, Decision Tree, Bayes Net, and the existing HotSprint database. In addition, we reveal several biological insights based on our analysis. We find that four features (the change of accessible surface area, percentage of the change of accessible surface area, size of a residue, and atomic contacts) are critical in predicting hot spots. Furthermore, we find that three residues (Tyr, Trp, and Phe) are abundant in hot spots through analyzing the distribution of amino acids.

  20. Hot spot assisted blinking suppression of CdSe quantum dots

    NASA Astrophysics Data System (ADS)

    Lu, Liu; Tong, Xuan; Zhang, Xu; Ren, Naifei; Jiang, Bo; Lu, Haifei

    2016-05-01

    This work compares the blinking of CdSe QDs on glass, single silver nanowire, and double aligned nanowires. The corresponding on-time fractions of these three cases are 50%, 70% and 85% respectively, which indicates that aligned double nanowires shows more efficient suppression than that of single nanowire. This phenomenon is attributed to the higher concentration of hot electron from hot spot between nanowires. Occupation of the non-radiative recombination centers by hot electrons from silver nanowires can be explained for the suppressed blinking behavior. The result has provided a novel pathway of suppressing the blinking behavior of QDs through plasmonic hot spot.

  1. Hot spots of wheat yield decline with rising temperatures.

    PubMed

    Asseng, Senthold; Cammarano, Davide; Basso, Bruno; Chung, Uran; Alderman, Phillip D; Sonder, Kai; Reynolds, Matthew; Lobell, David B

    2017-06-01

    Many of the irrigated spring wheat regions in the world are also regions with high poverty. The impacts of temperature increase on wheat yield in regions of high poverty are uncertain. A grain yield-temperature response function combined with a quantification of model uncertainty was constructed using a multimodel ensemble from two key irrigated spring wheat areas (India and Sudan) and applied to all irrigated spring wheat regions in the world. Southern Indian and southern Pakistani wheat-growing regions with large yield reductions from increasing temperatures coincided with high poverty headcounts, indicating these areas as future food security 'hot spots'. The multimodel simulations produced a linear absolute decline of yields with increasing temperature, with uncertainty varying with reference temperature at a location. As a consequence of the linear absolute yield decline, the relative yield reductions are larger in low-yielding environments (e.g., high reference temperature areas in southern India, southern Pakistan and all Sudan wheat-growing regions) and farmers in these regions will be hit hardest by increasing temperatures. However, as absolute yield declines are about the same in low- and high-yielding regions, the contributed deficit to national production caused by increasing temperatures is higher in high-yielding environments (e.g., northern India) because these environments contribute more to national wheat production. Although Sudan could potentially grow more wheat if irrigation is available, grain yields would be low due to high reference temperatures, with future increases in temperature further limiting production. © 2016 John Wiley & Sons Ltd.

  2. Magnetised accretion discs in Kerr spacetimes. II. Hot spots

    NASA Astrophysics Data System (ADS)

    García, Federico; Ranea-Sandoval, Ignacio F.; Johannsen, Tim

    2016-03-01

    Context. Quasi-periodic variability has been observed in a number of X-ray binaries that harbor black hole candidates. In general relativity, black holes are uniquely described by the Kerr metric and, according to the cosmic censorship conjecture, curvature singularities always have to be clothed by an event horizon. Aims: In this paper, we study the observed light curves that arise from orbiting hotspots in thin accretion discs around Kerr black holes and naked singularities, and the effect introduced by the presence of an external magnetic field. Methods: We employ a ray-tracing algorithm to calculate the light curves and power spectra of these hot spots as seen by a distant observer for uniform and dipolar magnetic field configurations, assuming a weak coupling between the magnetic field and the disc matter. Results: We show that the presence of an external dipolar magnetic field leads to potentially observable modifications of these light curves for both Kerr black holes and naked singularities, while an external uniform magnetic field has practically no effect. In particular, we demonstrate that the emission from a hotspot, which is orbiting near the innermost stable circular orbit of a naked singularity in a dipolar magnetic field, can be significantly harder than the emission of the same hotspot in the absence of this type of magnetic field. Conclusions: The comparison of our model with observational data may allow us to study the geometry of magnetic fields around compact objects and to test the cosmic censorship conjecture in conjunction with other observables, such as thermal continuum spectra and iron line profiles.

  3. Strong superchiral field in hot spots and its interaction with chiral molecules

    NASA Astrophysics Data System (ADS)

    Liu, Yineng

    We have found that strong superchiral fields created by surface plasmon resonance exist in hot spots of nonchiral plasmonic structure, which showed a chiral density greater than that of circularly polarized light by hundreds of times. We have demonstrated a direct correlation between the chirality of the local field and the circular dichroism (CD) response at the plasmon resonance bands induced by chiral molecules in the hot spots. Our results reveal that the wavelength-dependent superchiral fields in the hot spots can play a crucial role in the determination of the plasmonic CD effect. This finding is in contrast to the currently accepted physical model in which the electromagnetic field intensity in hot spots is a key factor to determine the peak intensity of the plasmonic CD spectrum. Some related experimental phenomena have been explained by using our theoretical analysis. The work was supported by the China National Natural Science Foundation (Grant No. 11504306).

  4. Flood basalts and hot-spot tracks: plume heads and tails.

    PubMed

    Richards, M A; Duncan, R A; Courtillot, V E

    1989-10-06

    Continental flood basalt eruptions have resulted in sudden and massive accumulations of basaltic lavas in excess of any contemporary volcanic processes. The largest flood basalt events mark the earliest volcanic activity of many major hot spots, which are thought to result from deep mantle plumes. The relative volumes of melt and eruption rates of flood basalts and hot spots as well as their temporal and spatial relations can be explained by a model of mantle plume initiation: Flood basalts represent plume "heads" and hot spots represent continuing magmatism associated with the remaining plume conduit or "tail." Continental rifting is not required, although it commonly follows flood basalt volcanism, and flood basalt provinces may occur as a natural consequence of the initiation of hot-spot activity in ocean basins as well as on continents.

  5. Determination of hot-spot susceptibility of multistring photovoltaic modules in a central-station application

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.; Weaver, R. W.; Ross, R. G., Jr.; Spencer, R.; Arnett, J. C.

    1984-01-01

    Part of the effort of the Jet Propulsion Laboratory (JPL) Flat-Plate Solar Array Project (FSA) includes a program to improve module and array reliability. A collaborative activity with industry dealing with the problem of hot-spot heating due to the shadowing of photovoltaic cells in modules and arrays containing several paralleled cell strings is described. The use of multiparallel strings in large central-station arrays introduces the likelihood of unequal current sharing and increased heating levels. Test results that relate power dissipated, current imbalance, cross-strapping frequency, and shadow configuration to hot-spot heating levels are presented. Recommendations for circuit design configurations appropriate to central-station applications that reduce the risk of hot-spot problems are offered. Guidelines are provided for developing hot-spot tests for arrays when current imbalance is a threat.

  6. Microstructure origin of hot spots in textured laser zone melting Bi-2212 monoliths

    NASA Astrophysics Data System (ADS)

    Lera, F.; Angurel, L. A.; Rojo, J. A.; Mora, M.; Recuero, S.; Arroyo, M. P.; Andrés, N.

    2005-11-01

    Hot spots are one of the main limitations in the development of large-scale high-power applications with superconducting materials. The application of digital speckle interferometry to detect inhomogeneous heating on ceramic superconductors allows the determining of a hot spot location in these materials before any damage is caused to the material. The technique detects deformations that are induced in the material due to dilatation, attaining a resolution of 0.45 µm /fringe. In this paper this technique has been applied to analyse the heating generation in Bi-2212 superconducting monoliths at room temperature and in operation conditions. In the first case a homogeneous heating is obtained, leading to a parallel fringe pattern. In the second case, a situation with an inhomogeneous heating origin has been detected. Once the position of this hot spot is determined, microstructure studies have been performed to determine which defects are responsible for hot spot generation.

  7. Process window limiting hot spot monitoring for high-volume manufacturing

    NASA Astrophysics Data System (ADS)

    Jochemsen, Marinus; Anunciado, Roy; Timoshkov, Vadim; Hunsche, Stefan; Zhou, Xinjian; Jones, Chris; Callan, Neal

    2016-03-01

    As process window margins for cutting edge DUV lithography continue to shrink, the impact of systematic patterning defects on final yield increases. Finding process window limiting hot spot patterns and monitoring them in high volume manufacturing (HVM) is increasingly challenging with conventional methods, as the size of critical defects can be below the resolution of traditional HVM inspection tools. We utilize a previously presented computational method of finding hot spot patterns by full chip simulation and use this to guide high resolution review tools by predicting the state of the hot spots on all fields of production wafers. In experiments with a 10nm node Metal LELELE vehicle we show a 60% capture rate of after-etch defects down to 3nm in size, at specific hot spot locations. By using the lithographic focus and dose correction knobs we can reduce the number of patterning defects for this test case by ~60%.

  8. Hot spot formation and stagnation properties in simulations of direct-drive NIF implosions

    NASA Astrophysics Data System (ADS)

    Schmitt, Andrew J.; Obenschain, Stephen P.

    2016-05-01

    We investigate different proposed methods of increasing the hot spot energy and radius in inertial confinement fusion implosions. In particular, shock mistiming (preferentially heating the inner edge of the target's fuel) and increasing the initial vapor gas density are investigated as possible control mechanisms. We find that only the latter is effective in substantially increasing the hot spot energy and dimensions while achieving ignition. In all cases an increase in the hot spot energy is accompanied by a decrease in the hot spot energy density (pressure) and both the yield and the gain of the target drop substantially. 2D simulations of increased vapor density targets predict an increase in the robustness of the target with respect to surface perturbations but are accompanied by significant yield degradation.

  9. Determination of hot-spot susceptibility of multistring photovoltaic modules in a central-station application

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.; Weaver, R. W.; Ross, R. G., Jr.; Spencer, R.; Arnett, J. C.

    1984-01-01

    Part of the effort of the Jet Propulsion Laboratory (JPL) Flat-Plate Solar Array Project (FSA) includes a program to improve module and array reliability. A collaborative activity with industry dealing with the problem of hot-spot heating due to the shadowing of photovoltaic cells in modules and arrays containing several paralleled cell strings is described. The use of multiparallel strings in large central-station arrays introduces the likelihood of unequal current sharing and increased heating levels. Test results that relate power dissipated, current imbalance, cross-strapping frequency, and shadow configuration to hot-spot heating levels are presented. Recommendations for circuit design configurations appropriate to central-station applications that reduce the risk of hot-spot problems are offered. Guidelines are provided for developing hot-spot tests for arrays when current imbalance is a threat.

  10. The hot-spot environment of SW Sex in a low state

    NASA Astrophysics Data System (ADS)

    Groot, Paul J.; Rutten, René G. M.; van Paradijs, Jan

    2000-04-01

    Based on observations obtained with the 2.5m Isaac Newton Telescope we show that the characteristics of the SW Sex stars can be explained by the dominance of a `hot-spot' like feature in the accretion disk. In SW Sex this `hot-spot' region is located at a distance of 0.5 RL 1 from the white-dwarf and is best visible at phase ϕ=0.95. The location of the hot-spot as deduced from spectral eclipse mapping coincides with the formation site of the main emission lines. We deduce that this hot-spot region is formed by a shock, which we speculate to be the consequence of a high mass-transfer rate and a long spin-period of the non-magnetic white dwarf.

  11. Calculation of the fast ion tail distribution for a spherically symmetric hot spot

    SciTech Connect

    McDevitt, C. J.; Tang, X.-Z.; Guo, Z.; Berk, H. L.

    2014-10-15

    The fast ion tail for a spherically symmetric hot spot is computed via the solution of a simplified Fokker-Planck collision operator. Emphasis is placed on describing the energy scaling of the fast ion distribution function in the hot spot as well as the surrounding cold plasma throughout a broad range of collisionalities and temperatures. It is found that while the fast ion tail inside the hot spot is significantly depleted, leading to a reduction of the fusion yield in this region, a surplus of fast ions is observed in the neighboring cold plasma region. The presence of this surplus of fast ions in the neighboring cold region is shown to result in a partial recovery of the fusion yield lost in the hot spot.

  12. Absence of ras-gene hot-spot mutations in canine fibrosarcomas and melanomas.

    PubMed

    Murua Escobar, Hugo; Günther, Kathrin; Richter, Andreas; Soller, Jan T; Winkler, Susanne; Nolte, Ingo; Bullerdiek, Jörn

    2004-01-01

    Point mutations within ras proto-oncogenes, particularly within the mutational hot-spot codons 12, 13 and 61, are frequently detected in human malignancies and in different types of experimentally-induced tumours in animals. So far little is known about ras mutations in naturally occurring canine fibrosarcomas or K-ras mutations in canine melanomas. To elucidate whether ras mutations exist in these naturally occurring tumours in dogs, in the present study we screened 13 canine fibrosarcomas, 2 feline fibrosarcomas and 11 canine melanomas for point mutations, particularly within the mutational hot-spots, making this the first study to investigate a large number of canine fibrosarcomas. None of the samples showed a K- or N-ras hot spot mutation. Thus, our data strongly suggest that ras mutations at the hot-spot loci are very rare and do not play a major role in the pathogenesis of the spontaneously occurring canine tumours investigated.

  13. Ion distribution in the hot spot of an inertial confinement fusion plasma

    NASA Astrophysics Data System (ADS)

    Tang, Xianzhu; Guo, Zehua; Berk, Herb

    2012-10-01

    Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform Fokker-Planck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by Fokker-Planck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated.

  14. Controlling surface-plasmon-polaritons launching with hot spot cylindrical waves in a metallic slit structure

    NASA Astrophysics Data System (ADS)

    Yao, Wenjie; Sun, Chengwei; Gong, Qihuang; Chen, Jianjun

    2016-09-01

    Plasmonic nanostructures, which are used to generate surface plasmon polaritons (SPPs), always involve sharp corners where the charges can accumulate. This can result in strong localized electromagnetic fields at the metallic corners, forming the hot spots. The influence of the hot spots on the propagating SPPs are investigated theoretically and experimentally in a metallic slit structure. It is found that the electromagnetic fields radiated from the hot spots, termed as the hot spot cylindrical wave (HSCW), can greatly manipulate the SPP launching in the slit structure. The physical mechanism behind the manipulation of the SPP launching with the HSCW is explicated by a semi-analytic model. By using the HSCW, unidirectional SPP launching is experimentally realized in an ultra-small metallic step-slit structure. The HSCW bridges the localized surface plasmons and the propagating surface plasmons in an integrated platform and thus may pave a new route to the design of plasmonic devices and circuits.

  15. Modeling heterogeneous high explosive burn with an explicit hot-spot process

    SciTech Connect

    Tang, P.K.; Johnson, J.N.; Forest, C.A.

    1985-01-01

    We present a method of treating high explosive burn with a multi-step process which includes the hot-spot excitation, decomposition, and the propagation of reaction into the region outside the hot spots. The basic features of this model are the separation of the thermal-mechanical and chemical processes, and the partition of the explosive into hot spots and the region exclusive of the hot spots. The thermal-mechanical aspects are formulated in a way similar to the chemical process. The combined processes lead to a set of rate equations for the mass fractions of reactants, intermediate states, and final products. The rates are expressed initially in terms of general characteristic times, but with specific phenomenological correlations introduced in the final model. Computational examples are given of simulated flyer plate impacts, short-shock initiation, corner turning, and shock desensitization. 19 refs., 9 figs.

  16. Hot spots and the hollowness of proton-proton interactions at high energies

    NASA Astrophysics Data System (ADS)

    Albacete, Javier L.; Soto-Ontoso, Alba

    2017-07-01

    We present a dynamical explanation of the hollowness effect observed in proton-proton scattering at √{ s} = 7 TeV. This phenomenon, not observed at lower energies, consists in a depletion of the inelasticity density at zero impact parameter of the collision. Our analysis is based on three main ingredients: we rely gluonic hot spots inside the proton as effective degrees of freedom for the description of the scattering process. Next we assume that some non-trivial correlation between the transverse positions of the hot spots inside the proton exists. Finally we build the scattering amplitude from a multiple scattering, Glauber-like series of collisions between hot spots. In our approach, the onset of the hollowness effect is naturally explained as due to the diffusion or growth of the hot spots in the transverse plane with increasing collision energy.

  17. Hot-spot mix in ignition-scale inertial confinement fusion targets

    DOE PAGES

    Regan, S. P.; Epstein, R.; Hammel, B. A.; ...

    2013-07-22

    Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot of ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed with x-ray spectroscopy on the National Ignition Facility. The amount of hot-spot mix mass is determined from the absolute brightness of the emergent Cu and Ge K-shell emission. The Cu and Ge dopants placed at different radial locations in the plastic ablator show the ablation-front hydrodynamic instability is primarily responsible for hot-spot mix. As a result, low neutron yields and hot-spot mix mass between 34(–13,+50) ng and 4000(–2970,+17 160) ng are observed.

  18. Hot Spots and Hot Times: Wildlife Road Mortality in a Regional Conservation Corridor

    NASA Astrophysics Data System (ADS)

    Garrah, Evelyn; Danby, Ryan K.; Eberhardt, Ewen; Cunnington, Glenn M.; Mitchell, Scott

    2015-10-01

    Strategies to reduce wildlife road mortality have become a significant component of many conservation efforts. However, their success depends on knowledge of the temporal and spatial patterns of mortality. We studied these patterns along the 1000 Islands Parkway in Ontario, Canada, a 37 km road that runs adjacent to the St. Lawrence River and bisects the Algonquin-to-Adirondacks international conservation corridor. Characteristics of all vertebrate road kill were recorded during 209 bicycle surveys conducted from 2008 to 2011. We estimate that over 16,700 vertebrates are killed on the road from April to October each year; most are amphibians, but high numbers of birds, mammals, and reptiles were also found, including six reptiles considered at-risk in Canada. Regression tree analysis was used to assess the importance of seasonality, weather, and traffic on road kill magnitude. All taxa except mammals exhibited distinct temporal peaks corresponding to phases in annual life cycles. Variations in weather and traffic were only important outside these peak times. Getis-Ord analysis was used to identify spatial clusters of mortality. Hot spots were found in all years for all taxa, but locations varied annually. A significant spatial association was found between multiyear hot spots and wetlands. The results underscore the notion that multi-species conservation efforts must account for differences in the seasonality of road mortality among species and that multiple years of data are necessary to identify locations where the greatest conservation good can be achieved. This information can be used to inform mitigation strategies with implications for conservation at regional scales.

  19. Hot Spots and Hot Times: Wildlife Road Mortality in a Regional Conservation Corridor.

    PubMed

    Garrah, Evelyn; Danby, Ryan K; Eberhardt, Ewen; Cunnington, Glenn M; Mitchell, Scott

    2015-10-01

    Strategies to reduce wildlife road mortality have become a significant component of many conservation efforts. However, their success depends on knowledge of the temporal and spatial patterns of mortality. We studied these patterns along the 1000 Islands Parkway in Ontario, Canada, a 37 km road that runs adjacent to the St. Lawrence River and bisects the Algonquin-to-Adirondacks international conservation corridor. Characteristics of all vertebrate road kill were recorded during 209 bicycle surveys conducted from 2008 to 2011. We estimate that over 16,700 vertebrates are killed on the road from April to October each year; most are amphibians, but high numbers of birds, mammals, and reptiles were also found, including six reptiles considered at-risk in Canada. Regression tree analysis was used to assess the importance of seasonality, weather, and traffic on road kill magnitude. All taxa except mammals exhibited distinct temporal peaks corresponding to phases in annual life cycles. Variations in weather and traffic were only important outside these peak times. Getis-Ord analysis was used to identify spatial clusters of mortality. Hot spots were found in all years for all taxa, but locations varied annually. A significant spatial association was found between multiyear hot spots and wetlands. The results underscore the notion that multi-species conservation efforts must account for differences in the seasonality of road mortality among species and that multiple years of data are necessary to identify locations where the greatest conservation good can be achieved. This information can be used to inform mitigation strategies with implications for conservation at regional scales.

  20. Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems

    SciTech Connect

    Nick Soelberg; Joe Enneking

    2011-05-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absoption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoring of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.

  1. A feature-based approach to modeling protein–protein interaction hot spots

    PubMed Central

    Cho, Kyu-il; Kim, Dongsup; Lee, Doheon

    2009-01-01

    Identifying features that effectively represent the energetic contribution of an individual interface residue to the interactions between proteins remains problematic. Here, we present several new features and show that they are more effective than conventional features. By combining the proposed features with conventional features, we develop a predictive model for interaction hot spots. Initially, 54 multifaceted features, composed of different levels of information including structure, sequence and molecular interaction information, are quantified. Then, to identify the best subset of features for predicting hot spots, feature selection is performed using a decision tree. Based on the selected features, a predictive model for hot spots is created using support vector machine (SVM) and tested on an independent test set. Our model shows better overall predictive accuracy than previous methods such as the alanine scanning methods Robetta and FOLDEF, and the knowledge-based method KFC. Subsequent analysis yields several findings about hot spots. As expected, hot spots have a larger relative surface area burial and are more hydrophobic than other residues. Unexpectedly, however, residue conservation displays a rather complicated tendency depending on the types of protein complexes, indicating that this feature is not good for identifying hot spots. Of the selected features, the weighted atomic packing density, relative surface area burial and weighted hydrophobicity are the top 3, with the weighted atomic packing density proving to be the most effective feature for predicting hot spots. Notably, we find that hot spots are closely related to π–related interactions, especially π · · · π interactions. PMID:19273533

  2. Analysis of microstructure-dependent shock dissipation and hot-spot formation in granular metalized explosive

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Sunada; Gonthier, Keith A.

    2016-07-01

    Variations in the microstructure of granular explosives (i.e., particle packing density, size, shape, and composition) can affect their shock sensitivity by altering thermomechanical fields at the particle-scale during pore collapse within shocks. If the deformation rate is fast, hot-spots can form, ignite, and interact, resulting in burn at the macro-scale. In this study, a two-dimensional finite and discrete element technique is used to simulate and examine shock-induced dissipation and hot-spot formation within low density explosives (68%-84% theoretical maximum density (TMD)) consisting of large ensembles of HMX (C4H8N8O8) and aluminum (Al) particles (size ˜ 60 -360 μm). Emphasis is placed on identifying how the inclusion of Al influences effective shock dissipation and hot-spot fields relative to equivalent ensembles of neat/pure HMX for shocks that are sufficiently strong to eliminate porosity. Spatially distributed hot-spot fields are characterized by their number density and area fraction enabling their dynamics to be described in terms of nucleation, growth, and agglomeration-dominated phases with increasing shock strength. For fixed shock particle speed, predictions indicate that decreasing packing density enhances shock dissipation and hot-spot formation, and that the inclusion of Al increases dissipation relative to neat HMX by pressure enhanced compaction resulting in fewer but larger HMX hot-spots. Ensembles having bimodal particle sizes are shown to significantly affect hot-spot dynamics by altering the spatial distribution of hot-spots behind shocks.

  3. Acoustic timescale characterization of hot spot ignition in thermally stratified mixtures

    NASA Astrophysics Data System (ADS)

    Reinbacher, Fynn; Regele, Jonathan

    2015-11-01

    Thermal stratification and the formation of hot spots in reactive mixtures are of key interest to characterize the autoignition behavior of charges in internal combustion engines. Critical gradient conditions and local maximum sizes of a finite hot spot centers can be used to describe such a hot spot. In previous work, one- and two-dimensional hot spots consisting of a linear temperature gradient and constant plateau have been characterized on an acoustic timescale. In the present work, random one-dimensional temperature fields, derived from Fourier superposition for temperature fluctuations with a temperature spectrum similar to Passot-Pouquet kinetic energy spectrum, are analyzed. The linear gradient constant plateau model is compared to a more realistic hot spot temperature profile. Hot spots in the one-dimensional temperature fields are modeled with linear gradients and constant plateaus in order to be characterized with acoustic time scale analysis. Probability distributions for different excitation-to-acoustic timescale ratios are calculated for a range of engine conditions.

  4. Arabidopsis meiotic crossover hot spots overlap with H2A.Z nucleosomes at gene promoters.

    PubMed

    Choi, Kyuha; Zhao, Xiaohui; Kelly, Krystyna A; Venn, Oliver; Higgins, James D; Yelina, Nataliya E; Hardcastle, Thomas J; Ziolkowski, Piotr A; Copenhaver, Gregory P; Franklin, F Chris H; McVean, Gil; Henderson, Ian R

    2013-11-01

    PRDM9 directs human meiotic crossover hot spots to intergenic sequence motifs, whereas budding yeast hot spots overlap regions of low nucleosome density (LND) in gene promoters. To investigate hot spots in plants, which lack PRDM9, we used coalescent analysis of genetic variation in Arabidopsis thaliana. Crossovers increased toward gene promoters and terminators, and hot spots were associated with active chromatin modifications, including H2A.Z, histone H3 Lys4 trimethylation (H3K4me3), LND and low DNA methylation. Hot spot-enriched A-rich and CTT-repeat DNA motifs occurred upstream and downstream, respectively, of transcriptional start sites. Crossovers were asymmetric around promoters and were most frequent over CTT-repeat motifs and H2A.Z nucleosomes. Pollen typing, segregation and cytogenetic analysis showed decreased numbers of crossovers in the arp6 H2A.Z deposition mutant at multiple scales. During meiosis, H2A.Z forms overlapping chromosomal foci with the DMC1 and RAD51 recombinases. As arp6 reduced the number of DMC1 or RAD51 foci, H2A.Z may promote the formation or processing of meiotic DNA double-strand breaks. We propose that gene chromatin ancestrally designates hot spots within eukaryotes and PRDM9 is a derived state within vertebrates.

  5. An automated decision-tree approach to predicting protein interaction hot spots.

    PubMed

    Darnell, Steven J; Page, David; Mitchell, Julie C

    2007-09-01

    Protein-protein interactions can be altered by mutating one or more "hot spots," the subset of residues that account for most of the interface's binding free energy. The identification of hot spots requires a significant experimental effort, highlighting the practical value of hot spot predictions. We present two knowledge-based models that improve the ability to predict hot spots: K-FADE uses shape specificity features calculated by the Fast Atomic Density Evaluation (FADE) program, and K-CON uses biochemical contact features. The combined K-FADE/CON (KFC) model displays better overall predictive accuracy than computational alanine scanning (Robetta-Ala). In addition, because these methods predict different subsets of known hot spots, a large and significant increase in accuracy is achieved by combining KFC and Robetta-Ala. The KFC analysis is applied to the calmodulin (CaM)/smooth muscle myosin light chain kinase (smMLCK) interface, and to the bone morphogenetic protein-2 (BMP-2)/BMP receptor-type I (BMPR-IA) interface. The results indicate a strong correlation between KFC hot spot predictions and mutations that significantly reduce the binding affinity of the interface. 2007 Wiley-Liss, Inc.

  6. Microwave interrogation of an air plasma plume as a model system for hot spots in explosives

    NASA Astrophysics Data System (ADS)

    Kane, Ronald J.; Tringe, Joseph W.; Klunder, Gregory L.; Baluyot, Emer V.; Densmore, John M.; Converse, Mark C.

    2017-01-01

    The evolution of hot spots within explosives is critical to understand for predicting how detonation waves form and propagate. However, it is challenging to observe hot spots directly because they are small (˜micron diameter), form quickly (much less than a microsecond), and many explosives of interest are optically opaque. Microwaves are well-suited to characterize hot spots because they readily penetrate most explosives. They also have sufficient temporal and spatial resolution to measure the coalescence of an ensemble of hot spots inside explosives. Here we employ 94 GHz microwaves to characterize the evolution of individual plasma plumes formed by laser ionization of air. We use interferometry to obtain plume diameter as a function of time. Although the plasma plumes are larger than individual hot spots in explosives, they expand rapidly and predictably, and their structure can be optically imaged. They are therefore useful model systems to establish the spatial and temporal limits of microwave interferometry (MI) for understanding more complex hot spot behavior in solid explosives.

  7. Microwave interrogation of an air plasma plume as a model system for hot spots in explosives

    NASA Astrophysics Data System (ADS)

    Kane, Ron; Tringe, Joseph; Klunder, Greg; Baluyot, Emer; Densmore, John; Converse, Mark

    2015-06-01

    The evolution of hot spots within explosives is critical to understand for predicting how detonation waves form and propagate. However, it is challenging to observe hot spots directly because they are small (~ micron diameter), form quickly (much less than a microsecond), and many explosives of interest are optically opaque. Microwaves are well-suited to characterize hot spots because they readily penetrate most explosives. They also have sufficient temporal and spatial resolution to measure the coalescence of an ensemble of hot spots inside explosives. Here we employ 94 GHz microwaves to characterize the evolution of individual plasma plumes formed by laser ionization of air. We use interferometry to obtain velocity records as a function of plume position and orientation. Although the plasma plumes are larger than individual hot spots in explosives, they expand rapidly and predictably, and their structure can be optically imaged. They are therefore useful model systems to establish the spatial and temporal limits of microwave interferometry (MI) for understanding more complex hot spot behavior in solid explosives. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Understanding and controlling hot spots of crime: the importance of formal and informal social controls.

    PubMed

    Weisburd, David; Groff, Elizabeth R; Yang, Sue-Ming

    2014-02-01

    Primary, secondary, and tertiary prevention programs that address opportunity or structural factors related to crime are usually delivered to entire cities, sections of cities or to specific neighborhoods, but our results indicate geographically targeting these programs to specific street segments may increase their efficacy. We link crime incidents to over 24,000 street segments (the two block faces on a street between two intersections) over a 16-year period, and identify distinct developmental patterns of crime at street segments using group-based trajectory analysis. One of these patterns, which we term chronic crime hot spots, includes just 1 % of street segments but is associated with 23 % of crime in the city during the study period. We then employ multinomial regression to identify the specific risk and protective factors that are associated with these crime hot spots. We find that both situational opportunities and social characteristics of places strongly distinguish chronic crime hot spots from areas with little crime. Our findings support recent efforts to decrease crime opportunities at crime hot spots through programs like hot spots policing, but they also suggest that social interventions directed at crime hot spots will be important if we are to do something about crime problems in the long run. We argue in concluding that micro level programs which focus crime prevention efforts on specific street segments have the potential to be less costly and more effective than those targeted at larger areas such as communities or neighborhoods.

  9. Protein-protein interface analysis and hot spots identification for chemical ligand design.

    PubMed

    Chen, Jing; Ma, Xiaomin; Yuan, Yaxia; Pei, Jianfeng; Lai, Luhua

    2014-01-01

    Rational design for chemical compounds targeting protein-protein interactions has grown from a dream to reality after a decade of efforts. There are an increasing number of successful examples, though major challenges remain in the field. In this paper, we will first give a brief review of the available methods that can be used to analyze protein-protein interface and predict hot spots for chemical ligand design. New developments of binding sites detection, ligandability and hot spots prediction from the author's group will also be described. Pocket V.3 is an improved program for identifying hot spots in protein-protein interface using only an apo protein structure. It has been developed based on Pocket V.2 that can derive receptor-based pharmacophore model for ligand binding cavity. Given similarities and differences between the essence of pharmacophore and hot spots for guiding design of chemical compounds, not only energetic but also spatial properties of protein-protein interface are used in Pocket V.3 for dealing with protein-protein interface. In order to illustrate the capability of Pocket V.3, two datasets have been used. One is taken from ASEdb and BID having experimental alanine scanning results for testing hot spots prediction. The other is taken from the 2P2I database containing complex structures of protein-ligand binding at the original protein-protein interface for testing hot spots application in ligand design.

  10. Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism?

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Staudigel, Hubert; Pringle, Malcolm S.; Wijbrans, Jan R.

    2003-10-01

    South Pacific intraplate volcanoes have been active since the Early Cretaceous. Their HIMU-EMI-EMII mantle sources can be traced back into the West Pacific Seamount Province (WPSP) using plate tectonic reconstructions, implying that these distinctive components are enduring features within the Earth's mantle for, at least, the last 120 Myr. These correlations are eminent on the scale of the WPSP and the South Pacific Thermal and Isotopic Anomaly (SOPITA), but the evolution of single hot spots emerges notably more complicated. Hot spots in the WPSP and SOPITA mantle regions typically display intermittent volcanic activity, longevities shorter than 40 Myr, superposition of hot spot volcanism, and motion relative to other hot spots. In this review, we use 40Ar/39Ar seamount ages and Sr-Nd-Pb isotopic signatures to map out Cretaceous volcanism in the WPSP and to characterize its evolution with respect to the currently active hot spots in the SOPITA region. Our plate tectonic reconstructions indicate cessation of volcanism during the Cretaceous for the Typhoon and Japanese hot spots; whereas the currently active Samoan, Society, Pitcairn and Marquesas hot spots lack long-lived counterparts in the WPSP. These hot spots may have become active during the last 20 Myr only. The other WPSP seamount trails can be only "indirectly" reconciled with hot spots in the SOPITA region. Complex age distributions in the Magellan, Anewetak, Ralik and Ratak seamount trails would necessitate the superposition of multiple volcanic trails generated by the Macdonald, Rurutu and Rarotonga hot spots during the Cretaceous; whereas HIMU-type seamounts in the Southern Wake seamount trail would require 350-500 km of hot spot motion over the last 100 Myr following its origination along the Mangaia-Rurutu "hotline" in the Cook-Austral Islands. These observations, however, violate all assumptions of the classical Wilson-Morgan hot spot hypothesis, indicating that long-lived, deep and fixed mantle

  11. SU-E-T-393: Investigation of Hot Spots in Tomotherapy 3D Conformal Breast Plan

    SciTech Connect

    Chen, Q; Siebers, J; Khandelwal, S

    2014-06-01

    Purpose: The purpose of this study is to determine the root-cause of hotspots inherent to Tomotherapy static beam 3D conformal radiotherapy (3DCRT) for breast treatment. ASTRO (ref here) recommends that IMRT be avoided for breast treatments. Despite Tomotherapy's inherent IMRT-like optimization and delivery, our experience at a Tomotherapy-only site has been that Tomotherapy 3DCRT fail to produce a clinically acceptable plan for 79% of our breast patients. Hot-spots have been one of the major obstacles. Methods: Eight lumpectomy patients were planned according to RTOG-1005 specification. Two or four tangential beams were used for 3DCRT breast planning. To spare the contralateral breast and ipsilateral lung, part of the PTV was not covered by the primary beam, yielding adjacent hot-spots. We hypothesize that the planning system creates hotspots adjacent to the cold spots to yield scatter radiation dose compensation in the blocked region. Various phantom and patient setup were used to test the hypothesis. Results: Hot spots outside of PTV in the range of 135% - 174% were observed for patient plan. It is confirmed that the PTV partial block causes the adjacent hot spot. The root cause is the optimizer quadratic objective function over- weighs improving the cold spot. The IMRT flexibility offered by Tomotherapy is counter-productive in static-beam 3DCRT breast treatment. For phantom case, as the Modulation-Factor increases from 1.1 to 5, the hot spot increases from 110% to 300%. Limiting the 3DCRT intensity modulation is shown to produce clinically acceptable plan. Conclusion: Most of the hot spots in Tomotherapy 3DCRT breast plan originate from the planning-system optimizer attempting to cover PTV cold spots rather than from the beam energy. Altering the objective function could improve clinical acceptability of static beam Tomotherapy 3DCRT.

  12. Exotic plant species invade hot spots of native plant diversity

    USGS Publications Warehouse

    Stohlgren, T.J.; Binkley, Dan; Chong, G.W.; Kalkhan, M.A.; Schell, L.D.; Bull, K.A.; Otsuki, Y.; Newman, G.; Bashkin, M.; Yowhan, S.

    1999-01-01

    ome theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2 subplots (20 1000-m2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2 subplots (16 1000-m2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm.At the 1-m2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2 plots was explained by the number of native plant species and the total percentage of soil carbon.At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and biodiversity

  13. Rec-Mediated Recombinational Hot Spot Activity in Bacteriophage Lambda. I. Hot Spot Activity Associated with Spi- Deletions and bio Substitutions

    PubMed Central

    McMilin, Kenneth D.; Stahl, Mary M.; Stahl, Franklin W.

    1974-01-01

    In order to survey the distribution along the bacteriophage λ chromosome of Rec-mediated recombination events, crosses are performed using conditions which block essentially all DNA synthesis. One parent is density-labeled and carries a genetic marker in the left terminal λ gene (A), while the other parent is unlabeled and carries a genetic marker in the right terminal λ gene (R). Both parents are deleted for the λ recombination genes int and red, together with other recombination-associated genes, by virtue of either (1) a pure deletion or (2) a bio insertion-deletion. The distribution in a cesium density gradient of the resulting A+R+ recombinant phage reflects the chromosomal distribution of the recombination events which gave rise to those phage.Crosses employing either of two different pure deletion phage strains exhibit recombinational hot spot activity located near the right end of the λ chromosome, between the cI and R genes. This hot spot activity persists when unlimited DNA synthesis is allowed. Crosses employing bio1-substituted phage strains exhibit recombinational hot spot activity located to the right of the middle of the chromosome and to the left of the cI gene. Crosses employing either bio1 or bio69-substituted phage strains indicate that the bio-associated hot spot activity occurs in the presence of DNA synthesis, but is dependent on a functional host recB gene. PMID:4415484

  14. Prediction of hot spots in protein interfaces using a random forest model with hybrid features.

    PubMed

    Wang, Lin; Liu, Zhi-Ping; Zhang, Xiang-Sun; Chen, Luonan

    2012-03-01

    Prediction of hot spots in protein interfaces provides crucial information for the research on protein-protein interaction and drug design. Existing machine learning methods generally judge whether a given residue is likely to be a hot spot by extracting features only from the target residue. However, hot spots usually form a small cluster of residues which are tightly packed together at the center of protein interface. With this in mind, we present a novel method to extract hybrid features which incorporate a wide range of information of the target residue and its spatially neighboring residues, i.e. the nearest contact residue in the other face (mirror-contact residue) and the nearest contact residue in the same face (intra-contact residue). We provide a novel random forest (RF) model to effectively integrate these hybrid features for predicting hot spots in protein interfaces. Our method can achieve accuracy (ACC) of 82.4% and Matthew's correlation coefficient (MCC) of 0.482 in Alanine Scanning Energetics Database, and ACC of 77.6% and MCC of 0.429 in Binding Interface Database. In a comparison study, performance of our RF model exceeds other existing methods, such as Robetta, FOLDEF, KFC, KFC2, MINERVA and HotPoint. Of our hybrid features, three physicochemical features of target residues (mass, polarizability and isoelectric point), the relative side-chain accessible surface area and the average depth index of mirror-contact residues are found to be the main discriminative features in hot spots prediction. We also confirm that hot spots tend to form large contact surface areas between two interacting proteins. Source data and code are available at: http://www.aporc.org/doc/wiki/HotSpot.

  15. APIS: accurate prediction of hot spots in protein interfaces by combining protrusion index with solvent accessibility

    PubMed Central

    2010-01-01

    Background It is well known that most of the binding free energy of protein interaction is contributed by a few key hot spot residues. These residues are crucial for understanding the function of proteins and studying their interactions. Experimental hot spots detection methods such as alanine scanning mutagenesis are not applicable on a large scale since they are time consuming and expensive. Therefore, reliable and efficient computational methods for identifying hot spots are greatly desired and urgently required. Results In this work, we introduce an efficient approach that uses support vector machine (SVM) to predict hot spot residues in protein interfaces. We systematically investigate a wide variety of 62 features from a combination of protein sequence and structure information. Then, to remove redundant and irrelevant features and improve the prediction performance, feature selection is employed using the F-score method. Based on the selected features, nine individual-feature based predictors are developed to identify hot spots using SVMs. Furthermore, a new ensemble classifier, namely APIS (A combined model based on Protrusion Index and Solvent accessibility), is developed to further improve the prediction accuracy. The results on two benchmark datasets, ASEdb and BID, show that this proposed method yields significantly better prediction accuracy than those previously published in the literature. In addition, we also demonstrate the predictive power of our proposed method by modelling two protein complexes: the calmodulin/myosin light chain kinase complex and the heat shock locus gene products U and V complex, which indicate that our method can identify more hot spots in these two complexes compared with other state-of-the-art methods. Conclusion We have developed an accurate prediction model for hot spot residues, given the structure of a protein complex. A major contribution of this study is to propose several new features based on the protrusion index of

  16. Alternative hot spot formation techniques using liquid deuterium-tritium layer inertial confinement fusion capsules

    SciTech Connect

    Olson, R. E.; Leeper, R. J.

    2013-09-27

    The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ~34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid” (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.

  17. Alternative hot spot formation techniques using liquid deuterium-tritium layer inertial confinement fusion capsules

    SciTech Connect

    Olson, R. E.; Leeper, R. J.

    2013-09-15

    The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ∼34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid” (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.

  18. Magmatic effects of the Cobb hot spot on the Juan de Fuca Ridge

    USGS Publications Warehouse

    Chadwick, J.; Perfit, M.; Ridley, I.; Jonasson, I.; Kamenov, G.; Chadwick, W.; Embley, R.; le, Roux P.; Smith, M.

    2005-01-01

    The interaction of the Juan de Fuca Ridge with the Cobb hot spot has had a considerable influence on the magmatism of the Axial Segment of the ridge, the second-order segment that overlies the hot spot. In addition to the construction of the large volcanic edifice of Axial Seamount, the Axial Segment has shallow bathymetry and a prevalence of constructional volcanic features along its 100-km length, suggesting that hot spot-derived magmas supplement and oversupply the ridge. Lavas are generally more primitive at Axial Seamount and more evolved in the Axial Segment rift zones, suggesting that fractional crystallization is enhanced with increasing distance from the hot spot because of a reduced magma supply and more rapid cooling. Although the Cobb hot spot is not an isotopically enriched plume, it produces lavas with some distinct geochemical characteristics relative to normal mid-ocean ridge basalt, such as enrichments in alkalis and highly incompatible trace elements, that can be used as tracers to identify the presence and prevalence of the hot spot influence along the ridge. These characteristics are most prominent at Axial Seamount and decline in gradients along the Axial Segment. The physical model that can best explain the geochemical observations is a scenario in which hot spot and mid-ocean ridge basalt (MORB) magmas mix to varying degrees, with the proportions controlled by the depth to the MORB source. Modeling of two-component mixing suggests that MORB is the dominant component in most Axial Segment basalts. Copyright 2005 by the American Geophysical Union.

  19. Joule heating hot spot at high latitudes in the afternoon sector

    NASA Astrophysics Data System (ADS)

    Cai, L.; Aikio, A. T.; Milan, S. E.

    2016-07-01

    The afternoon Joule heating hot spot has been studied statistically by using the EISCAT Svalbard Radar (ESR) measurements at 75.4° Corrected Geomagnetic latitude (CGMLAT) and the OMNI solar wind data base. For a small subset of events, the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) field-aligned current distributions have been available. The main results are as follows. Afternoon Joule heating hot spots are associated with high values of ionospheric electric fields and slightly enhanced Pedersen conductances. The Joule heating hot spot values are larger in summer than in winter, which can be explained by the higher Pedersen conductances during summer than winter. The afternoon Joule heating hot spots are located close to the reversals of the large-scale field-aligned current systems. The most common location is close to the Region 1/Region 2 boundary and those events are associated with sunward convecting F region plasma. In a few cases, the hot spots take place close to the Region 1/Region 0 boundary and then the ionospheric plasma is convecting antisunward. The hot spots may occur both during slow (<450 km/s) and high (>450 km/s) speed solar wind conditions. During slow-speed solar wind events, the dominant interplanetary magnetic field (IMF) direction is southward, which is the general requirement for the low-latitude magnetic merging at the dayside magnetopause. During high-speed solar wind, also northward IMF conditions appear, but those are associated with large values of the IMF |By| component, making again the dayside magnetopause merging possible. Finally, the measured afternoon hot spot Joule heating rates are not a linear function of the solar wind energy coupling function.

  20. Geometrically centered region: a "wet" model of protein binding hot spots not excluding water molecules.

    PubMed

    Li, Zhenhua; Li, Jinyan

    2010-12-01

    A protein interface can be as "wet" as a protein surface in terms of the number of immobilized water molecules. This important water information has not been explicitly taken by computational methods to model and identify protein binding hot spots, overlooking the water role in forming interface hydrogen bonds and in filing cavities. Hot spot residues are usually clustered at the core of the protein binding interfaces. However, traditional machine learning methods often identify the hot spot residues individually, breaking the cooperativity of the energetic contribution. Our idea in this work is to explore the role of immobilized water and meanwhile to capture two essential properties of hot spots: the compactness in contact and the far distance from bulk solvent. Our model is named geometrically centered region (GCR). The detection of GCRs is based on novel tripartite graphs, and atom burial levels which are a concept more intuitive than SASA. Applying to a data set containing 355 mutations, we achieved an F measure of 0.6414 when ΔΔG ≥ 1.0 kcal/mol was used to define hot spots. This performance is better than Robetta, a benchmark method in the field. We found that all but only one of the GCRs contain water to a certain degree, and most of the outstanding hot spot residues have water-mediated contacts. If the water is excluded, the burial level values are poorly related to the ΔΔG, and the model loses its performance remarkably. We also presented a definition for the O-ring of a GCR as the set of immediate neighbors of the residues in the GCR. Comparative analysis between the O-rings and GCRs reveals that the newly defined O-ring is indeed energetically less important than the GCR hot spot, confirming a long-standing hypothesis. Copyright © 2010 Wiley-Liss, Inc.

  1. Robust Identification of Binding Hot Spots Using Continuum Electrostatics: Application to Hen Egg-White Lysozyme

    PubMed Central

    2011-01-01

    Binding hot spots, protein regions with high binding affinity, can be identified by using X-ray crystallography or NMR spectroscopy to screen libraries of small organic molecules that tend to cluster at such hot spots. FTMap, a direct computational analogue of the experimental screening approaches, uses 16 different probe molecules for global sampling of the surface of a target protein on a dense grid and evaluates the energy of interaction using an empirical energy function that includes a continuum electrostatic term. Energy evaluation is based on the fast Fourier transform correlation approach, which allows for the sampling of billions of probe positions. The grid sampling is followed by off-grid minimization that uses a more detailed energy expression with a continuum electrostatics term. FTMap identifies the hot spots as consensus clusters formed by overlapping clusters of several probes. The hot spots are ranked on the basis of the number of probe clusters, which predicts their binding propensity. We applied FTMap to nine structures of hen egg-white lysozyme (HEWL), whose hot spots have been extensively studied by both experimental and computational methods. FTMap found the primary hot spot in site C of all nine structures, in spite of conformational differences. In addition, secondary hot spots in sites B and D that are known to be important for the binding of polysaccharide substrates were found. The predicted probe–protein interactions agree well with those seen in the complexes of HEWL with various ligands and also agree with an NMR-based study of HEWL in aqueous solutions of eight organic solvents. We argue that FTMap provides more complete information on the HEWL binding site than previous computational methods and yields fewer false-positive binding locations than the X-ray structures of HEWL from crystals soaked in organic solvents. PMID:22092261

  2. What controls the distribution and tectono-magmatic features of oceanic hot spot volcanoes

    NASA Astrophysics Data System (ADS)

    Acocella, Valerio; Vezzoli, Luigina

    2016-04-01

    Hot spot oceanic volcanoes worldwide show significant deviations from the classic Hawaiian reference model; these mainly concern the distribution of edifices and overall tectono-magmatic features, as the development of the volcanic rift zones and extent of flank instability. Here we try to explain these deviations investigating and comparing the best-known hot spot oceanic volcanoes. At a general scale, these volcanoes show an age-distance progression ranging from focused to scattered. This is here explained as due to several independent factors, as the thermal or mechanical weakening of the plate (due to the lithosphere thickness or regional structures, respectively), or the plume structure. At a more detailed scale, hot spot volcanoes show recurrent features, including mafic shield edifices with summit caldera and volcanic rift zones, often at the head of an unstable flank. However, despite this recurrence, a widespread tectono-magmatic variability is often found. Here we show how this variability depends upon the magma supply and age of the oceanic crust (influencing the thickness of the overlying pelagic sediments). Well-developed rift zones and larger collapses are found on hot spot volcanoes with higher supply rate and older crust, as Hawaii and Canary Islands. Poorly-developed rift zones and limited collapses occur on hot spot volcanoes with lower supply rate and younger crust, as Easter Island and Ascension. Transitional features are observed at hot spots with intermediate productivity (Cape Verde, Reunion, Society Islands and, to a minor extent, the Azores), whereas the scarcity or absence of pelagic sediments may explain the lack of collapses and developed rift zones in the productive Galapagos hot spot.

  3. Hot spot(s) of the lung in technetium-99m albumin colloid liver-spleen scintigraphy: case report

    SciTech Connect

    Shih, W.J.; Brandenburg, S.; Coupal, J.J.; Sullivan, J.D.; Beeler, J.A.; Magoun, S.; Ryo, U.Y.

    1988-06-01

    The authors replaced /sup 99m/Tc albumin colloid for /sup 99m/Tc sulfur colloid as a radiopharmaceutical for liver-spleen imaging and found two instances of hot spot(s) in the lung. The preparation procedure of albumin colloid is easier and more convenient as compared to that of sulfur colloid. Whereas replacement of /sup 99m/Tc sulfur colloid by /sup 99m/Tc albumin colloid is inevitable, it should be emphasized that one should avoid blood withdrawal in the syringe containing albumin colloid to prevent formation of clot(s) during the venous puncture for /sup 99m/Tc albumin colloid.

  4. Hydrologic indicators of hot spots and hot moments of mercury methylation along river corridors

    NASA Astrophysics Data System (ADS)

    Singer, Michael; Harrison, Lee; Donovan, Patrick; Blum, Joel; Marvin-DiPasquale, Mark

    2016-04-01

    The biogeochemical cycling of metals and other contaminants river-floodplain corridors is controlled by microbial activity is often affected by dynamic redox conditions. Riverine flooding thus has the potential to affect speciation of redox-sensitive metals such as mercury (Hg). Therefore, flow history over a period of decades potentially holds information on past production of bioavailable Hg. We investigate this process within a Northern California river system that has a legacy of industrial-scale 19th century hydraulic gold mining. In the first known application of this methodology, we combine hydraulic modeling, measurements of Hg species in sediment and biota, and first-order calculations to assess the role of river floodplains in producing monomethylmercury (MMHg), which accumulates in local and migratory biota. We identify areas that represent 'hot spots' (frequently inundated areas of floodplains) and 'hot moments' (floodplain areas inundated for consecutive long periods). We show that the probability of MMHg production in each sector of the river system is dependent on the spatial patterns of overbank flow and drainage, which affect its long-term redox history. MMHg bioaccumulation within the aquatic food web may pose a major risk to humans and waterfowl that eat migratory salmonids, which are being encouraged to come up these rivers to spawn, and there appears to be no end to MMHg production under a regime of increasingly common large floods with extended duration. These findings identify river floodplains as periodic, temporary, yet important, loci of biogeochemical transformation in which contaminants may undergo change during limited periods of the historical hydrologic record. We suggest that inundation is the primary driver of MMHg production in river corridors and that the entire flow history must be analyzed in terms of magnitude and frequency of inundation in order to accurately assess biogeochemical risks, rather than merely highlighting the

  5. Analysis of recombinational hot spots associated with the p haplotype fo the mouse MHC

    SciTech Connect

    Heine, D.; Khambata, S.; Wydner, K.S.; Passmore, H.C.

    1994-09-01

    Most of the recombination events detected within the major histocompatibility complex (MHC) of the mouse fall into areas of limited physical size that have been designated recombinational hot spots. One of these hot spots, associated with the Ea gene, appears to be active only in the presence of the p haplotype of the MHC. To study the regulation of the Ea recombinational hot spot and its haplotype specificity, a high-resolution comparative map fo the MHC and adjacent regions was completed in four different backcrosses carrying the p haplotype. This mapping study utilized a total of 29 PCR-based molecular markers, including 7 newly developed markers spanning the region between Pim1 and D17Mit11 on Chromosome 17. The analysis of a total of 1093 backcross animals: (1) revealed that the presence of the p haplotype of the MHC is not sufficient to induce recombination at the Ea hot spot in a dominant manner, and (2) resulted in the definition of a new intra-MHC recombinational hot spot between the Tnfb and the H2-D genes.

  6. Functional Roles of Acetylated Histone Marks at Mouse Meiotic Recombination Hot Spots.

    PubMed

    Getun, Irina V; Wu, Zhen; Fallahi, Mohammad; Ouizem, Souad; Liu, Qin; Li, Weimin; Costi, Roberta; Roush, William R; Cleveland, John L; Bois, Philippe R J

    2017-02-01

    Meiotic recombination initiates following the formation of DNA double-strand breaks (DSBs) by the Spo11 endonuclease early in prophase I, at discrete regions in the genome coined "hot spots." In mammals, meiotic DSB site selection is directed in part by sequence-specific binding of PRDM9, a polymorphic histone H3 (H3K4Me3) methyltransferase. However, other chromatin features needed for meiotic hot spot specification are largely unknown. Here we show that the recombinogenic cores of active hot spots in mice harbor several histone H3 and H4 acetylation and methylation marks that are typical of open, active chromatin. Further, deposition of these open chromatin-associated histone marks is dynamic and is manifest at spermatogonia and/or pre-leptotene-stage cells, which facilitates PRDM9 binding and access for Spo11 to direct the formation of DSBs, which are initiated at the leptotene stage. Importantly, manipulating histone acetylase and deacetylase activities established that histone acetylation marks are necessary for both hot spot activity and crossover resolution. We conclude that there are functional roles for histone acetylation marks at mammalian meiotic recombination hot spots.

  7. Functional Roles of Acetylated Histone Marks at Mouse Meiotic Recombination Hot Spots

    PubMed Central

    Wu, Zhen; Fallahi, Mohammad; Ouizem, Souad; Liu, Qin; Li, Weimin; Costi, Roberta; Roush, William R.; Bois, Philippe R. J.

    2016-01-01

    ABSTRACT Meiotic recombination initiates following the formation of DNA double-strand breaks (DSBs) by the Spo11 endonuclease early in prophase I, at discrete regions in the genome coined “hot spots.” In mammals, meiotic DSB site selection is directed in part by sequence-specific binding of PRDM9, a polymorphic histone H3 (H3K4Me3) methyltransferase. However, other chromatin features needed for meiotic hot spot specification are largely unknown. Here we show that the recombinogenic cores of active hot spots in mice harbor several histone H3 and H4 acetylation and methylation marks that are typical of open, active chromatin. Further, deposition of these open chromatin-associated histone marks is dynamic and is manifest at spermatogonia and/or pre-leptotene-stage cells, which facilitates PRDM9 binding and access for Spo11 to direct the formation of DSBs, which are initiated at the leptotene stage. Importantly, manipulating histone acetylase and deacetylase activities established that histone acetylation marks are necessary for both hot spot activity and crossover resolution. We conclude that there are functional roles for histone acetylation marks at mammalian meiotic recombination hot spots. PMID:27821479

  8. EDF experience with {open_quotes}hot spot{close_quotes} management

    SciTech Connect

    Guio, J.M. de

    1995-03-01

    During the past few years, {open_quotes}hot spots{close_quotes} due to the presence of particles of metal activated during their migration through the reactor core, have been detected at several French pressurized water reactor (PWR) units. These {open_quotes}hot spots,{close_quotes} which generate very high dose rates (from about 10 Gy/h to 200 G/h) are a significant factor in increase occupational exposures during outrates. Of particular concern are the difficult cases which prolong outage duration and increase the volume of radiological waste. Confronted with this situation, Electricite de France (EDF) has set up a national research group, as part of its ALARA program, to establish procedures and techniques to avoid, detect, and eliminate of hot spots. In particular, specific processes have been developed to eliminate these hot spots which are most costly in terms of occupational exposure due to the need for reactor maintenance. This paper sets out the general approach adopted at EDF so far to cope with the problem of hot spots, illustrated by experience at Blayais 3 and 4.

  9. NASA Spots "Hot Towers" in Intensifying Tropical Storm Frank

    NASA Image and Video Library

    "Hot towers" (orange) were visible in this animated flyby of data from the Global Precipitation Measurement mission or GPM satellite. On July 21, the GPM Core satellite measured rainfall rates of o...

  10. Photoproduct frequency is not the major determinant of UV base substitution hot spots or cold spots in human cells

    SciTech Connect

    Brash, D.E.; Seetharam, S.; Kraemer, K.H.; Seidman, M.M.; Bredberg, A.

    1987-06-01

    The role of UV radiation-induced photoproducts in initiating base substitution mutations in human cells was examined by measuring photoproduct frequency distributions and mutations in a supF tRNA gene on a shuttle vector plasmid transfected into DNA repair-deficient cells (xeroderma pigmentosum, complementation group A) and into normal cells. Frequencies of cyclobutane dimers and pyrimidine-pyrimidone (6-4) photoproducts varied by as much as 80-fold at different dipyrimidine sites within the gene. All transition mutations occurred at dipyrimidine sites, predominantly at cytosine, with a 17-fold variation in mutation frequency between different sites. Removal of greater than 99% of the cyclobutane dimers by in vitro photoreactivation before transfection reduced the mutation frequency while preserving the mutation distribution, indicating that (i) cytosine-containing cyclobutane dimers were the major mutagenic lesions at these sites and (ii) cytosine-containing non-cyclobutane dimer photoproducts were also mutagenic lesions. However, at individual dipyrimidine sites neither the frequency of cyclobutane dimers nor the frequency of pyrimidine-pyrimidone (6-4) photoproducts correlated with the mutation frequency, even in the absence of excision repair. Mutation hot spots occurred at sites with low or high frequency of photoproduct formation and mutation cold spots occurred at sites with many photoproducts. These results suggest that although photoproducts are required for UV mutagenesis, the prominence of most mutation hot spots and cold spots is primarily determined by DNA structural features rather than by the frequency of DNA photoproducts.

  11. Allele-dependent recombination frequency: homology requirement in meiotic recombination at the hot spot in the mouse major histocompatibility complex.

    PubMed

    Yoshino, M; Sagai, T; Lindahl, K F; Toyoda, Y; Moriwaki, K; Shiroishi, T

    1995-05-20

    Meiotic recombination break joints in the mouse major histocompatibility complex (MHC) are clustered within short segments known as hot spots. We systematically investigated the requirement for sequence homology between two chromosomes for recombination activity at the hot spot next to the Lmp2 gene. The results indicated that a high rate of recombination required a high degree of similarity of overall genome structure at the hot spot. In particular, the same copy number of repetitive sequences within the hot spot was essential for a high frequency of recombination, suggesting that recombination in mouse meiosis is more sensitive to heterozygous deletion or insertion of DNA than to mismatches of single-base substitutions.

  12. How To Light Special Hot Spots in Multiparticle-Film Configurations.

    PubMed

    Chen, Shu; Meng, Ling-Yan; Shan, Hang-Yong; Li, Jian-Feng; Qian, Lihua; Williams, Christopher T; Yang, Zhi-Lin; Tian, Zhong-Qun

    2016-01-26

    The precise control over the locations of hot spots in a nanostructured ensemble is of great importance in plasmon-enhanced spectroscopy, chemical sensing, and super-resolution optical imaging. However, for multiparticle configurations over metal films that involve localized and propagating surface plasmon modes, the locations of hot spots are difficult to predict due to complex plasmon competition and synergistic effects. In this work, theoretical simulations based on multiparticle-film configurations predict that the locations of hot spots can be efficiently controlled in the particle-particle gaps, the particle-film junctions, or in both, by suppressing or promoting specific plasmonic coupling effects in specific wavelength ranges. These findings offer an avenue to obtain strong Raman signals from molecules situated on single crystal surfaces and simultaneously avoid signal interference from particle-particle gaps.

  13. Multiphysics Simulations of Hot-Spot Initiation in Shocked Insensitive High-Explosive

    NASA Astrophysics Data System (ADS)

    Najjar, Fady; Howard, W. M.; Fried, L. E.

    2010-11-01

    Solid plastic-bonded high-explosive materials consist of crystals with micron-sized pores embedded. Under mechanical or thermal insults, these voids increase the ease of shock initiation by generating high-temperature regions during their collapse that might lead to ignition. Understanding the mechanisms of hot-spot initiation has significant research interest due to safety, reliability and development of new insensitive munitions. Multi-dimensional high-resolution meso-scale simulations are performed using the multiphysics software, ALE3D, to understand the hot-spot initiation. The Cheetah code is coupled to ALE3D, creating multi-dimensional sparse tables for the HE properties. The reaction rates were obtained from MD Quantum computations. Our current predictions showcase several interesting features regarding hot spot dynamics including the formation of a "secondary" jet. We will discuss the results obtained with hydro-thermo-chemical processes leading to ignition growth for various pore sizes and different shock pressures.

  14. Wavelength modulated SERS hot spot distribution in 1D nanostructures on metal film

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Zeng, Xiping; Liu, Ting; Zhang, Xuemei; Wei, Hua; Huang, Yingzhou; Liu, Anping; Wang, Shuxia; Wen, Weijia

    2016-10-01

    Surface plasmons confining strong electromagnetic fields near metal surfaces, well-known as hot spots, provide an extremely efficient platform for surface-enhanced Raman scattering (SERS). In this work, SERS spectra of probing molecules in a silver particle-wire 1D nanostructure on a thin gold film are investigated. The Raman features of SERS spectra collected at the particle-wire joints exhibit an obvious wavelength dependence phenomenon. This result is confirmed electromagnetic field simulation, revealing that hot spot distribution is sensitively influenced by the wavelength of incident light at the joints. Further studies indicate this wavelength dependence of hot spot distribution is immune to influence from the geometric shape of the particle or the angle between wire and particle, which improves fabrication tolerance. This technology may have promising applications in surface plasmon related fields, such as ultrasensors, solar energy and selective surface catalysis.

  15. Detecting fluorescence hot-spots using mosaic maps generated from multimodal endoscope imaging

    NASA Astrophysics Data System (ADS)

    Yang, Chenying; Soper, Timothy D.; Seibel, Eric J.

    2013-03-01

    Fluorescence labeled biomarkers can be detected during endoscopy to guide early cancer biopsies, such as high-grade dysplasia in Barrett's Esophagus. To enhance intraoperative visualization of the fluorescence hot-spots, a mosaicking technique was developed to create full anatomical maps of the lower esophagus and associated fluorescent hot-spots. The resultant mosaic map contains overlaid reflectance and fluorescence images. It can be used to assist biopsy and document findings. The mosaicking algorithm uses reflectance images to calculate image registration between successive frames, and apply this registration to simultaneously acquired fluorescence images. During this mosaicking process, the fluorescence signal is enhanced through multi-frame averaging. Preliminary results showed that the technique promises to enhance the detectability of the hot-spots due to enhanced fluorescence signal.

  16. Nano rolling-circle amplification for enhanced SERS hot spots in protein microarray analysis.

    PubMed

    Yan, Juan; Su, Shao; He, Shijiang; He, Yao; Zhao, Bin; Wang, Dongfang; Zhang, Honglu; Huang, Qing; Song, Shiping; Fan, Chunhai

    2012-11-06

    Although "hot spots" have been proved to contribute to surface enhanced Raman scattering (SERS), less attention was paid to increase the number of the "hot spot" to directly enhance the Raman signals in bioanalytical systems. Here we report a new strategy based on nano rolling-circle amplification (nanoRCA) and nano hyperbranched rolling-circle amplification (nanoHRCA) to increase "hot spot" groups for protein microarrays. First, protein and ssDNA are coassembled on gold nanoparticles, making the assembled probe have both binding ability and hybridization ability. Second, the ssDNAs act as primers to initiate in situ RCA reaction to produced long ssDNAs. Third, a large number of SERS probes are loaded on the long ssDNA templetes, allowing thousands of SERS probes involved in each biomolecular recognition event. The strategy offered high-efficiency Raman enhancement and could detect less than 10 zeptomolar protein molecules in protein microarray analysis.

  17. Small Molecules Engage Hot Spots through Cooperative Binding To Inhibit a Tight Protein-Protein Interaction.

    PubMed

    Liu, Degang; Xu, David; Liu, Min; Knabe, William Eric; Yuan, Cai; Zhou, Donghui; Huang, Mingdong; Meroueh, Samy O

    2017-03-28

    Protein-protein interactions drive every aspect of cell signaling, yet only a few small-molecule inhibitors of these interactions exist. Despite our ability to identify critical residues known as hot spots, little is known about how to effectively engage them to disrupt protein-protein interactions. Here, we take advantage of the ease of preparation and stability of pyrrolinone 1, a small-molecule inhibitor of the tight interaction between the urokinase receptor (uPAR) and its binding partner, the urokinase-type plasminogen activator uPA, to synthesize more than 40 derivatives and explore their effect on the protein-protein interaction. We report the crystal structure of uPAR bound to previously discovered pyrazole 3 and to pyrrolinone 12. While both 3 and 12 bind to uPAR and compete with a fluorescently labeled peptide probe, only 12 and its derivatives inhibit the full uPAR·uPA interaction. Compounds 3 and 12 mimic and engage different hot-spot residues on uPA and uPAR, respectively. Interestingly, 12 is involved in a π-cation interaction with Arg-53, which is not considered a hot spot. Explicit-solvent molecular dynamics simulations reveal that 3 and 12 exhibit dramatically different correlations of motion with residues on uPAR. Free energy calculations for the wild-type and mutant uPAR bound to uPA or 12 show that Arg-53 interacts with uPA or with 12 in a highly cooperative manner, thereby altering the contributions of hot spots to uPAR binding. The direct engagement of peripheral residues not considered hot spots through π-cation or salt-bridge interactions could provide new opportunities for enhanced small-molecule engagement of hot spots to disrupt challenging protein-protein interactions.

  18. Testing a class of non-Kerr metrics with hot spots orbiting SgrA*

    SciTech Connect

    Liu, Dan; Li, Zilong; Bambi, Cosimo E-mail: zilongli@fudan.edu.cn

    2015-01-01

    SgrA*, the supermassive black hole candidate at the Galactic Center, exhibits flares in the X-ray, NIR, and sub-mm bands that may be interpreted within a hot spot model. Light curves and images of hot spots orbiting a black hole are affected by a number of special and general relativistic effects, and they can be potentially used to check whether the object is a Kerr black hole of general relativity. However, in a previous study we have shown that the relativistic features are usually subdominant with respect to the background noise and the model-dependent properties of the hot spot, and eventually it is at most possible to estimate the frequency of the innermost stable circular orbit. In this case, tests of the Kerr metric are only possible in combination with other measurements. In the present work, we consider a class of non-Kerr spacetimes in which the hot spot orbit may be outside the equatorial plane. These metrics are difficult to constrain from the study of accretion disks and indeed current X-ray observations of stellar-mass and supermassive black hole candidates cannot put interesting bounds. Here we show that near future observations of SgrA* may do it. If the hot spot is sufficiently close to the massive object, the image affected by Doppler blueshift is brighter than the other one and this provides a specific observational signature in the hot spot's centroid track. We conclude that accurate astrometric observations of SgrA* with an instrument like GRAVITY should be able to test this class of metrics, except in the more unlikely case of a small viewing angle.

  19. Comparison of Hot Spot Formation in DT ice layer and DT liquid layer ICF Capsules

    NASA Astrophysics Data System (ADS)

    Olson, R. E.; Leeper, R. J.

    2013-10-01

    Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts - the DT wetted CH foam concept and the ``fast formed liquid'' (FFL) concept - will be described and compared to simulations of standard DT ice layer capsules. The wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low (DT ice) and high (DT liquid) vapor pressure capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules will be less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the relative simplicity of the hot spot formation technique might lead to a more robust ignition experiment, a reduction in sensitivity to low-mode x-ray flux asymmetry, and an improvement in the computational prediction of hot spot behavior. This work was performed under the auspices of the U. S. DOE by LANL under contract DE-AC52-06NA25396. Sandia is a multiprogram laboratory operated by the Sandia Corporation, a Lockheed-Martin Company, for the U.S. DOE under contract DE-AC04-94AL85000.

  20. Investigating La Réunion Hot Spot From Crust to Core

    NASA Astrophysics Data System (ADS)

    Barruol, Guilhem; Sigloch, Karin

    2013-06-01

    Whether volcanic intraplate hot spots are underlain by deep mantle plumes continues to be debated 40 years after the hypothesis was proposed by Morgan [1972]. Arrivals of buoyant plume heads may have been among the most disruptive agents in Earth's history, initiating continental breakup, altering global climate, and triggering mass extinctions. Further, with the temporary shutdown of European air traffic in 2010 caused by the eruption of Eyjafjallajökull, a geologically routine eruption in the tail end of the presumed Iceland plume, the world witnessed an intrusion of hot spot activity into modern-day life.

  1. Automated analysis of hot spot X-ray images at the National Ignition Facility

    SciTech Connect

    Khan, S. F. Izumi, N.; Glenn, S.; Tommasini, R.; Benedetti, L. R.; Ma, T.; Pak, A.; Springer, P.; Bradley, D. K.; Town, R. P. J.; Kyrala, G. A.

    2016-11-15

    At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

  2. Content-based analysis of Ki-67 stained meningioma specimens for automatic hot-spot selection.

    PubMed

    Swiderska-Chadaj, Zaneta; Markiewicz, Tomasz; Grala, Bartlomiej; Lorent, Malgorzata

    2016-10-07

    Hot-spot based examination of immunohistochemically stained histological specimens is one of the most important procedures in pathomorphological practice. The development of image acquisition equipment and computational units allows for the automation of this process. Moreover, a lot of possible technical problems occur in everyday histological material, which increases the complexity of the problem. Thus, a full context-based analysis of histological specimens is also needed in the quantification of immunohistochemically stained specimens. One of the most important reactions is the Ki-67 proliferation marker in meningiomas, the most frequent intracranial tumour. The aim of our study is to propose a context-based analysis of Ki-67 stained specimens of meningiomas for automatic selection of hot-spots. The proposed solution is based on textural analysis, mathematical morphology, feature ranking and classification, as well as on the proposed hot-spot gradual extinction algorithm to allow for the proper detection of a set of hot-spot fields. The designed whole slide image processing scheme eliminates such artifacts as hemorrhages, folds or stained vessels from the region of interest. To validate automatic results, a set of 104 meningioma specimens were selected and twenty hot-spots inside them were identified independently by two experts. The Spearman rho correlation coefficient was used to compare the results which were also analyzed with the help of a Bland-Altman plot. The results show that most of the cases (84) were automatically examined properly with two fields of view with a technical problem at the very most. Next, 13 had three such fields, and only seven specimens did not meet the requirement for the automatic examination. Generally, the Automatic System identifies hot-spot areas, especially their maximum points, better. Analysis of the results confirms the very high concordance between an automatic Ki-67 examination and the expert's results, with a Spearman

  3. Powerful Radio Galaxies with Simbol-X: Lobes and Hot Spots

    SciTech Connect

    Migliori, G.

    2009-05-11

    We present here the first Simbol-X simulations of the extended components, lobes and hot spots, of the radio galaxies. We use the paradigmatic case of Pictor A to test the capabilities of Simbol-X in this field of studies. Simulations demonstrate that Simbol-X will be able not only to perform spatially resolved studies on the lobes of radio galaxies below 10 keV but also to observe, for the first time, hard X-ray emission from the hot spots. These extremely promising results show the considerable potentiality of Simbol-X in studying interaction phenomena between relativistic plasma and surrounding environment.

  4. Powerful Radio Galaxies with Simbol-X: Lobes and Hot Spots

    NASA Astrophysics Data System (ADS)

    Migliori, G.; Grandi, P.; Angelini, L.; Raimondi, L.; Torresi, E.; Palumbo, G. G. C.

    2009-05-01

    We present here the first Simbol-X simulations of the extended components, lobes and hot spots, of the radio galaxies. We use the paradigmatic case of Pictor A to test the capabilities of Simbol-X in this field of studies. Simulations demonstrate that Simbol-X will be able not only to perform spatially resolved studies on the lobes of radio galaxies below 10 keV but also to observe, for the first time, hard X-ray emission from the hot spots. These extremely promising results show the considerable potentiality of Simbol-X in studying interaction phenomena between relativistic plasma and surrounding environment.

  5. Excess ellipticity of hot and cold spots in the WMAP data?

    SciTech Connect

    Berntsen, Eirik; Hansen, Frode K. E-mail: frodekh@astro.uio.no

    2013-12-10

    We investigate claims of excess ellipticity of hot and cold spots in the Wilkinson Microwave Anisotropy Probe (WMAP) data. Using the cosmic microwave background (CMB) data from 7 yr of observations by the WMAP satellite, we find, contrary to previous claims of a 10σ detection of excess ellipticity in the 3 yr data, that the ellipticity of hot and cold spots is perfectly consistent with simulated CMB maps based on the concordance cosmology. We further test for excess obliquity and excess skewness/kurtosis of ellipticity and obliquity and find the WMAP7 data consistent with Gaussian simulated maps.

  6. Local topographic influences on vision restoration hot spots after brain damage.

    PubMed

    Sabel, Bernhard A; Kruse, Rudolf; Wolf, Fred; Guenther, Tobias

    2013-01-01

    Vision restoration training (VRT) in hemianopia patients leads to visual field enlargements, but the mechanisms of this vision restoration are not known. To investigate the role of residual vision in recovery, we studied topographic features of visual field charts and determined residual functions in local regions and their immediate surround. We analyzed High Resolution Perimetry visual field charts of hemianopic stroke patients (n = 23) before and after 6 months of VRT and identified all local visual field regions with ("hot spots", n = 688) or without restoration ("cold spots", n = 3426). Topographic features of these spots at baseline where then related to (i) their respective local residual function, (ii) residual activity in their spatial neighbourhood, and (iii) their distance to the scotoma border estimated in cortical coordinates following magnification factor transformation. Visual field areas had a greater probability of becoming vision restoration hot spots if they had more residual activity in both local areas and in a spatially limited surround of 5° of visual angle. Hot spots were typically also located closer than 4 mm from the scotoma border in cortical coordinates. Thus, restoration depended on residual activity in both the local region and its immediate surround. Our findings confirm the special role of residual structures in visual field restoration which is likely mediated by partially surviving neuronal elements. Because the immediate but not distant surround influenced outcome of individual spots, we propose that lateral interactions, known to play a role in perceptual learning and receptive field plasticity, also play a major role in vision restoration.

  7. Dissection of a circumscribed recombination hot spot in HIV-1 after a single infectious cycle.

    PubMed

    Galetto, Román; Giacomoni, Véronique; Véron, Michel; Negroni, Matteo

    2006-02-03

    Recombination is a major source of genetic heterogeneity in the human immunodeficiency virus type 1 (HIV-1) population. The main mechanism responsible for the generation of recombinant viruses is a process of copy choice between the two copies of genomic RNA during reverse transcription. We previously identified, after a single cycle of infection of cells in culture, a recombination hot spot within the gp120 gene, corresponding to the top portion of a RNA hairpin. Here, we determine that the hot region is circumscribed to 18 nucleotides located in the descending strand of the stem, following the sense of reverse transcription. Three factors appeared to be important, albeit at different extents, for the high rate of recombination observed in this region. The position of the hot sequence in the context of the RNA structure appears crucial, because changing its location within this structure triggered differences in recombination up to 20-fold. Another pivotal factor is the presence of a perfectly identical sequence between donor and acceptor RNA in the region of transfer, because single or double nucleotide differences in the hot spot were sufficient to almost completely abolish recombination in the region. Last, the primary structure of the hot region also influenced recombination, although with effects only in the 2-3-fold range. Altogether, these results provide the first molecular dissection of a hot spot in infected cells and indicate that several factors contribute to the generation of a site of preferential copy choice.

  8. Enceladus' Geysers and Small-scale Thermal Hot Spots: Spatial Correlations and Implications

    NASA Astrophysics Data System (ADS)

    Porco, C.; Helfenstein, P.; Goguen, J.

    2016-12-01

    The geysering south polar terrain (SPT) of Enceladus has been a major focus of the Cassini mission ever since Cassini's first sighting of it in images taken in early 2005 (1). A high resolution imaging survey of the region conducted over the course of seven years resulted in the identification of 100 geysers erupting from the four main fractures crossing the SPT (2). The Cassini Visual and Infrared Mapping Spectrometer (VIMS) detected enhanced thermal emission arising from these fractures and taking the form of small-scale ( ≤ 10 meter) discrete spots (3,4). Four of these hot spot observations have already been spatially associated with four geysers on the Baghdad Sulcus fracture (2). The inferred spatial correlation and small size of each hot spot eliminated shear heating along the near-surface walls of the fractures as the source of the heat and erupting materials. Instead, it was concluded that condensation of vapor (and liquid), and the deposition of latent heat, on the near-surface vent walls, and the subsequent conduction of that heat to the surface, was the source of the observed thermal emission. This indicated that the hot spots are the secondary signature of a geyser eruption process deeply rooted in the moon's sub-surface liquid water reservoir (2). We extend the examination of these relationships to include seven additional VIMS observations of hot spots. At the present time, we have associated a total of 11 VIMS hot spot observations with 13 (maybe 14) geysers distributed over all four tiger stripe fractures. It's not uncommon for the locations of multiple (often two but sometimes three) surveyed geysers to overlap within estimated uncertainties. This can occur when they have different 3D orientations, making them identifiable in our 2014 survey as distinct features; However, the raw, thermally unmodeled VIMS maps, with their (relatively) coarse resolution, may register at that location only one corresponding hot spot. It is also possible that

  9. Comparison between hot spot modeling and measurement of a superconducting hot electron bolometer mixer at submillimeter wavelengths

    NASA Astrophysics Data System (ADS)

    Miao, Wei; Delorme, Yan; Feret, Alexandre; Lefevre, Rolland; Lecomte, Benoit; Dauplay, Fred; Krieg, Jean-Michel; Beaudin, Gerard; Zhang, Wen; Ren, Yuan; Shi, Sheng-Cai

    2009-11-01

    This paper presents the modeling and measurement of a quasioptical niobium nitride superconducting hot electron bolometer mixer at submillimeter wavelengths. The modeling is performed with a distributed hot spot model which is based on solving a heat balance equation for electron temperature along the superconducting microbridge. Particular care has been taken during the modeling concerning the temperature-dependent resistance and the bias current dependence of the critical temperature of the device. The dc and mixing characteristics of this mixer have been computed and we have observed a quite good match between the predicted and the measured results for both dc characteristics and mixing performances at submillimeter wavelengths.

  10. Sewage treatment plant serves as a hot-spot reservoir of integrons and gene cassettes.

    PubMed

    Ma, Liping; Zhang, Xu-Xiang; Zhao, Fuzheng; Wu, Bing; Cheng, Shupei; Yang, Liuyan

    2013-04-01

    This study investigated the occurrence and abundance of class 1 integrons and related antibiotic resistance genes (ARGs) in a sewage treatment plant (STP) of China. Totally, 189 bacterial strains were isolated from influent, activated sludge and effluent, and 40 isolates contained the integons with a complete structure. The intl1-carrying isolates were found to harbor two types of gene cassettes: dfr17-aadA5 and aadA2, conferring resistances to trimethoprim and streptomycin, which were further confirmed by antimicrobial susceptibility analysis. Many other gene cassettes were carried on integron, including qnrVC1, catB-8-blaoxa-10-aadA1-aac(6'), aadB-aacA29b, aadA2, aac(6')-1b, aadA6 and aadA12, which were detected using DNA cloning. Quantitative real time PCR showed that over 99% of the integrons was eliminated in activated sludge process, but average copy number of integrons in given bacterial cells was increased by 56% in treated sewage. Besides integrons, other mobile gene elements (MGEs) were present in the STP with high abundance. MGEs and the associated ARGs may be wide-spread in STPs, which constitute a potential hot spot for selection of antibiotic resistant bacteria and horizontal transfer of ARGs.

  11. Narrow-bandwidth high-order harmonics driven by long-duration hot spots

    NASA Astrophysics Data System (ADS)

    Kozlov, Maxim; Kfir, Ofer; Fleischer, Avner; Kaplan, Alex; Carmon, Tal; Schwefel, Harald G. L.; Bartal, Guy; Cohen, Oren

    2012-06-01

    We predict and investigate the emission of high-order harmonics by atoms that cross intense laser hot spots that last for a nanosecond or longer. An atom that moves through a nanometer-scale hot spot at characteristic thermal velocity can emit high-order harmonics in a similar fashion to an atom that is irradiated by a short-duration (picosecond-scale) laser pulse. We analyze the collective emission from a thermal gas and from a jet of atoms. In both cases, the line shape of a high-order harmonic exhibits a narrow spike with spectral width that is determined by the bandwidth of the driving laser. Finally, we discuss a scheme for producing long-duration laser hot spots with intensity in the range of the intensity threshold for high-harmonic generation. In the proposed scheme, the hot spot is produced by a long laser pulse that is consecutively coupled to a high-quality micro-resonator and a metallic nano-antenna. This system may be used for generating ultra-narrow bandwidth extreme-ultraviolet radiation through frequency up-conversion of a low-cost compact pump laser.

  12. Environmental assessment hot spots of perforated forest in the eastern United States

    Treesearch

    Kurt H. Riitters; John W. Coulston

    2005-01-01

    National assessments of forest fragmentation satisfy international biodiversity conventions, but they do not identify specific places where ecological impacts are likely. In this article, we identify geographic concentrations (hot spots) of forest located near holes in otherwise intact forest canopies (perforated forest) in the eastern United States, and we describe...

  13. Microstrucutral Modeling of Hot Spot and Failure Mechanisms in RDX Energetic Aggregates

    DTIC Science & Technology

    2014-01-01

    with adiabatic plasticity heating, thermal decomposition, thermal conduction, and dissipated heat to predict and understand hot spot formation for a...which resulted in unbounded temperatures due to localized plasticity and thermal decomposition at the peripheries of the voids. Viscous dissipation...morphologies, dislocation densities, and crystal-binder interactions were coupled with adiabatic plasticity heating, thermal decomposition, thermal

  14. Analysis of Binding Site Hot Spots on the Surface of Ras GTPase

    SciTech Connect

    Buhrman, Greg; O; #8242; Connor, Casey; Zerbe, Brandon; Kearney, Bradley M.; Napoleon, Raeanne; Kovrigina, Elizaveta A.; Vajda, Sandor; Kozakov, Dima; Kovrigin, Evgenii L.; Mattos, Carla

    2012-09-17

    We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the 'off' and 'on' allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target.

  15. Shock induced hot-spot formation and subsequent decomposition in granular, porous hexanitrostilbene explosive

    SciTech Connect

    Hayes, D B

    1981-01-01

    Experimental and theoretical studies on granular, porous hexanitrostilbene (HNS) explosive have yielded an increased understanding of microstructural processes occurring during initiation by shock loading. Experiments involved the planar impact of HNS specimens onto fused-silica targets. Chemical decomposition liberated gaseous products, causing the pressure in the HNS to rise. Velocity interferometry measured material velocity, hence, pressure at the fused silica/HNS interface. An analysis of this pressure excursion yields chemical decomposition history. The data are interpreted in terms of a quantitative two-temperature model which considers hot spots to be formed at pore sites as a result of the irreversible work accompanying the shock. Subsequently, decomposition completion is achieved by burn fronts which propagate radially out from each hot spot at a velocity which can be determined from the bulk decomposition rate. Analysis of the experimental data in the context of the model yields several important results: the delay times corresponding to hot-spot decomposition are shorter than expected; model calculations show about the same inferred hot-spot temperature for different initial porosities and particle sizes in HNS, shock-loaded to equal pressures, which is consistent with experimental results.

  16. Identification of hot spots of malaria transmission for targeted malaria control.

    PubMed

    Bousema, Teun; Drakeley, Chris; Gesase, Samwel; Hashim, Ramadhan; Magesa, Stephen; Mosha, Frank; Otieno, Silas; Carneiro, Ilona; Cox, Jonathan; Msuya, Eliapendavyo; Kleinschmidt, Immo; Maxwell, Caroline; Greenwood, Brian; Riley, Eleanor; Sauerwein, Robert; Chandramohan, Daniel; Gosling, Roly

    2010-06-01

    Variation in the risk of malaria within populations is a frequently described but poorly understood phenomenon. This heterogeneity creates opportunities for targeted interventions but only if hot spots of malaria transmission can be easily identified. We determined spatial patterns in malaria transmission in a district in northeastern Tanzania, using malaria incidence data from a cohort study involving infants and household-level mosquito sampling data. The parasite prevalence rates and age-specific seroconversion rates (SCRs) of antibodies against Plasmodium falciparum antigens were determined in samples obtained from people attending health care facilities. Five clusters of higher malaria incidence were detected and interpreted as hot spots of transmission. These hot spots partially overlapped with clusters of higher mosquito exposure but could not be satisfactorily predicted by a probability model based on environmental factors. Small-scale local variation in malaria exposure was detected by parasite prevalence rates and SCR estimates for samples of health care facility attendees. SCR estimates were strongly associated with local malaria incidence rates and predicted hot spots of malaria transmission with 95% sensitivity and 85% specificity. Serological markers were able to detect spatial variation in malaria transmission at the microepidemiological level, and they have the potential to form an effective method for spatial targeting of malaria control efforts.

  17. Piezo-Electric Hypothesis for Hot Spot Formation Leading to Detonation

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Cawkwell, M. J.; Ramos, K. J.

    2015-06-01

    The impact to detonation sequence has been a long standing mystery in high explosives (HE). It is widely recognized that detonation begins in spatially-localized ``hot spots'' where chemistry initiates, but the physical mechanisms leading to hot spot formation are unknown. Here we revisit an old hypothesis, first suggested by Maycock and Grabenstein, that piezo-electric effects may be the cause of hot spot formation since most solid HE materials are observed to be highly piezo-electric. In this scenario, shock-induced pressure leads to electric fields of 100's MV/m, sufficient for dielectric breakdown and breaking chemical bonds, rather than via thermal effects. Extrapolation of statically measured piezo-electric coefficients for several HE materials suggests that shock pressures > 100-kbar might lead to field strengths > 100 - 1000 MV/m, but no definitive experimental proof has been obtained to support this. Here we discuss possible experiments to test this hypothesis by measuring the electric field in dynamic HE experiments correlated with hot spot formation. Work performed under the auspices of DOE by LANL under contract DE-AC52-06NA25396.

  18. Evolution and Persistence of 5-um Hot Spots at the Galileo Probe entry Latitude

    NASA Technical Reports Server (NTRS)

    Fisher, B. M.

    1997-01-01

    We present a study on the longtudinal locations, morphology and evolution of the 5-um hot spots at 6.5 deg. N latitude (planetocentric), from an extensive IRTF-NSFCAM data set spanning more that 3 years, which includes the date of the Galileo Probe entry.

  19. Building Electromagnetic Hot Spots in Living Cells via Target-Triggered Nanoparticle Dimerization.

    PubMed

    Zhou, Wen; Li, Qiang; Liu, Huiqiao; Yang, Jie; Liu, Dingbin

    2017-03-10

    Electromagnetic hot spots of surface-enhanced Raman scattering have been extensively employed for bioanalysis in solution or on a substrate, but building hot spots in living systems for probing targets of interest has not been achieved yet because of the complex and dynamic physiological environment. Herein, we show that a target-programmed nanoparticle dimerization can be combined with the background-free Raman reporters (alkyne, C≡C; nitrile, C≡N) for multiplexed imaging of microRNAs (miRNAs) in living cells. The in situ formation of plasmonic dimers results in an intense hot spot, thus dramatically enhancing the Raman signals of the reporters residing in the hot spot. More significantly, the reporters exhibit single nonoverlapping peaks in the cellular Raman-silent region (1800-2800 cm(-1)), thus eliminating spectral unmixing and background interference. A 3D Raman mapping technique was harnessed to monitor the spatial distribution of the dimers and thus the multiple miRNAs in cells. This approach could be extended to probe other biomarkers of interest for monitoring specific pathophysiological events at the live-cell level.

  20. Encoding Random Hot Spots of a Volume Gold Nanorod Assembly for Ultralow Energy Memory.

    PubMed

    Dai, Qiaofeng; Ouyang, Min; Yuan, Weiguang; Li, Jinxiang; Guo, Banghong; Lan, Sheng; Liu, Songhao; Zhang, Qiming; Lu, Guang; Tie, Shaolong; Deng, Haidong; Xu, Yi; Gu, Min

    2017-09-01

    Data storage with ultrahigh density, ultralow energy, high security, and long lifetime is highly desirable in the 21st century and optical data storage is considered as the most promising way to meet the challenge of storing big data. Plasmonic coupling in regularly arranged metallic nanoparticles has demonstrated its superior properties in various applications due to the generation of hot spots. Here, the discovery of the polarization and spectrum sensitivity of random hot spots generated in a volume gold nanorod assembly is reported. It is demonstrated that the two-photon-induced absorption and two-photon-induced luminescence of the gold nanorods adjacent to such hot spots are enhanced significantly because of plasmonic coupling. The polarization, wavelength, and spatial multiplexing of the hot spots can be realized by using an ultralow energy of only a few picojoule per pulse, which is two orders of magnitude lower than the value in the state-of-the-art technology that utilizes isolated gold nanorods. The ultralow recording energy reduces the cross-talk between different recording channels and makes it possible to realize rewriting function, improving significantly both the quality and capacity of optical data storage. It is anticipated that the demonstrated technology can facilitate the development of multidimensional optical data storage for a greener future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Evolution and Persistence of 5-um Hot Spots at the Galileo Probe entry Latitude

    NASA Technical Reports Server (NTRS)

    Fisher, B. M.

    1997-01-01

    We present a study on the longtudinal locations, morphology and evolution of the 5-um hot spots at 6.5 deg. N latitude (planetocentric), from an extensive IRTF-NSFCAM data set spanning more that 3 years, which includes the date of the Galileo Probe entry.

  2. Temperature and composition of Saturn's polar hot spots and hexagon.

    PubMed

    Fletcher, L N; Irwin, P G J; Orton, G S; Teanby, N A; Achterberg, R K; Bjoraker, G L; Read, P L; Simon-Miller, A A; Howett, C; de Kok, R; Bowles, N; Calcutt, S B; Hesman, B; Flasar, F M

    2008-01-04

    Saturn's poles exhibit an unexpected symmetry in hot, cyclonic polar vortices, despite huge seasonal differences in solar flux. The cores of both vortices are depleted in phosphine gas, probably resulting from subsidence of air into the troposphere. The warm cores are present throughout the upper troposphere and stratosphere at both poles. The thermal structure associated with the marked hexagonal polar jet at 77 degrees N has been observed for the first time. Both the warm cyclonic belt at 79 degrees N and the cold anticyclonic zone at 75 degrees N exhibit the hexagonal structure.

  3. Online Adaptive Hyperthermia Treatment Planning During Locoregional Heating to Suppress Treatment-Limiting Hot Spots.

    PubMed

    Kok, H Petra; Korshuize-van Straten, Linda; Bakker, Akke; de Kroon-Oldenhof, Rianne; Geijsen, Elisabeth D; Stalpers, Lukas J A; Crezee, Johannes

    2017-07-14

    Adequate tumor temperatures during hyperthermia are essential for good clinical response, but excessive heating of normal tissue should be avoided. This makes locoregional heating using phased array systems technically challenging. Online application of hyperthermia treatment planning could help to improve the heating quality. The aim of this study was to evaluate the clinical benefit of online treatment planning during treatment of pelvic tumors heated with the AMC-8 locoregional hyperthermia system. For online adaptive hyperthermia treatment planning, a graphical user interface was developed. Electric fields were calculated in a preprocessing step using our in-house-developed finite-difference-based treatment planning system. This allows instant calculation of the temperature distribution for user-selected phase-amplitude settings during treatment and projection onto the patient's computed tomographic scan for online visualization. Online treatment planning was used for 14 treatment sessions in 8 patients to reduce the patients' reports of hot spots while maintaining the same level of tumor heating. The predicted decrease in hot spot temperature should be at least 0.5°C, and the tumor temperature should decrease less than 0.2°C. These predictions were compared with clinical data: patient feedback about the hot spot and temperature measurements in the tumor region. In total, 17 hot spot reports occurred during the 14 sessions, and the alternative settings predicted the hot spot temperature to decrease by at least 0.5°C, which was confirmed by the disappearance of all 17 hot spot reports. At the same time, the average tumor temperature was predicted to change on average -0.01°C (range, -0.19°C to 0.34°C). The measured tumor temperature change was on average only -0.02°C (range, -0.26°C to 0.31°C). In only 2 cases the temperature decrease was slightly larger than 0.2°C, but at most it was 0.26°C. Online application of hyperthermia treatment planning is

  4. Hot-spot mix in ignition-scale implosions on the NIF

    SciTech Connect

    Regan, S. P.; Epstein, R.; McCrory, R. L.; Meyerhofer, D. D.; Sangster, T. C.; Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Doeppner, T.; Edwards, M. J.; Farley, D. R.; Glenn, S.; Glenzer, S. H.; and others

    2012-05-15

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive [D. S. Clark et al., Phys. Plasmas 17, 052703 (2010)]. Richtmyer-Meshkov and Rayleigh-Taylor hydrodynamic instabilities seeded by high-mode () ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase [B. A. Hammel et al., Phys. Plasmas 18, 056310 (2011)]. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium-hydrogen-deuterium (THD) and deuterium-tritium (DT) cryogenic targets and gas-filled plastic-shell capsules, which replace the THD layer with a mass-equivalent CH layer, was examined. The inferred amount of hot-spot-mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code [J. J. MacFarlane et al., High Energy Density Phys. 3, 181 (2006)], is typically below the 75-ng allowance for hot-spot mix [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. Predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.

  5. Role of hydrodynamic instability growth in hot-spot mass gain and fusion performance of inertial confinement fusion implosions

    SciTech Connect

    Srinivasan, Bhuvana; Tang, Xian-Zhu

    2014-10-15

    In an inertial confinement fusion target, energy loss due to thermal conduction from the hot-spot will inevitably ablate fuel ice into the hot-spot, resulting in a more massive but cooler hot-spot, which negatively impacts fusion yield. Hydrodynamic mix due to Rayleigh-Taylor instability at the gas-ice interface can aggravate the problem via an increased gas-ice interfacial area across which energy transfer from the hot-spot and ice can be enhanced. Here, this mix-enhanced transport effect on hot-spot fusion-performance degradation is quantified using contrasting 1D and 2D hydrodynamic simulations, and its dependence on effective acceleration, Atwood number, and ablation speed is identified.

  6. Galapagos-OIB signature in southern Central America: Mantle refertilization by arc-hot spot interaction

    NASA Astrophysics Data System (ADS)

    Gazel, Esteban; Carr, Michael J.; Hoernle, Kaj; Feigenson, Mark D.; Szymanski, David; Hauff, Folkmar; van den Bogaard, Paul

    2009-02-01

    Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an ocean island basalt (OIB) affinity, similar to the Galapagos-OIB lavas (e.g., Ba/La < 40, La/Yb > 10, 206Pb/204Pb > 18.8). Our new data for Costa Rica suggest that this signature, unusual for a convergent margin, has a relatively recent origin (Late Miocene ˜6 Ma). We also show that there was a transition from typical arc magmas (analogous to the modern Nicaraguan volcanic front) to OIB-like magmas similar to the Galapagos hot spot. The geographic distribution of the Galapagos signature in recent lavas from southern Central America is present landward from the subduction of the Galapagos hot spot tracks (the Seamount Province and the Cocos/Coiba Ridge) at the Middle American Trench. The higher Pb isotopic ratios, relatively lower Sr and Nd isotopic ratios, and enriched incompatible-element signature of central Costa Rican magmas can be explained by arc-hot spot interaction. The isotopic ratios of central Costa Rican lavas require the subducting Seamount Province (Northern Galapagos Domain) component, whereas the isotopic ratios of the adakites and alkaline basalts from southern Costa Rica and Panama are in the geochemical range of the subducting Cocos/Coiba Ridge (Central Galapagos Domain). Geological and geochemical evidence collectively indicate that the relatively recent Galapagos-OIB signature in southern Central America represents a geochemical signal from subducting Galapagos hot spot tracks, which started to collide with the margin ˜8 Ma ago. The Galapagos hot spot contribution decreases systematically along the volcanic front from central Costa Rica to NW Nicaragua.

  7. Co-Occurring Atomic Contacts for the Characterization of Protein Binding Hot Spots.

    PubMed

    Liu, Qian; Ren, Jing; Song, Jiangning; Li, Jinyan

    2015-01-01

    A binding hot spot is a small area at a protein-protein interface that can make significant contribution to binding free energy. This work investigates the substantial contribution made by some special co-occurring atomic contacts at a binding hot spot. A co-occurring atomic contact is a pair of atomic contacts that are close to each other with no more than three covalent-bond steps. We found that two kinds of co-occurring atomic contacts can play an important part in the accurate prediction of binding hot spot residues. One is the co-occurrence of two nearby hydrogen bonds. For example, mutations of any residue in a hydrogen bond network consisting of multiple co-occurring hydrogen bonds could disrupt the interaction considerably. The other kind of co-occurring atomic contact is the co-occurrence of a hydrophobic carbon contact and a contact between a hydrophobic carbon atom and a π ring. In fact, this co-occurrence signifies the collective effect of hydrophobic contacts. We also found that the B-factor measurements of several specific groups of amino acids are useful for the prediction of hot spots. Taking the B-factor, individual atomic contacts and the co-occurring contacts as features, we developed a new prediction method and thoroughly assessed its performance via cross-validation and independent dataset test. The results show that our method achieves higher prediction performance than well-known methods such as Robetta, FoldX and Hotpoint. We conclude that these contact descriptors, in particular the novel co-occurring atomic contacts, can be used to facilitate accurate and interpretable characterization of protein binding hot spots.

  8. Co-Occurring Atomic Contacts for the Characterization of Protein Binding Hot Spots

    PubMed Central

    Liu, Qian; Ren, Jing; Song, Jiangning; Li, Jinyan

    2015-01-01

    A binding hot spot is a small area at a protein-protein interface that can make significant contribution to binding free energy. This work investigates the substantial contribution made by some special co-occurring atomic contacts at a binding hot spot. A co-occurring atomic contact is a pair of atomic contacts that are close to each other with no more than three covalent-bond steps. We found that two kinds of co-occurring atomic contacts can play an important part in the accurate prediction of binding hot spot residues. One is the co-occurrence of two nearby hydrogen bonds. For example, mutations of any residue in a hydrogen bond network consisting of multiple co-occurring hydrogen bonds could disrupt the interaction considerably. The other kind of co-occurring atomic contact is the co-occurrence of a hydrophobic carbon contact and a contact between a hydrophobic carbon atom and a π ring. In fact, this co-occurrence signifies the collective effect of hydrophobic contacts. We also found that the B-factor measurements of several specific groups of amino acids are useful for the prediction of hot spots. Taking the B-factor, individual atomic contacts and the co-occurring contacts as features, we developed a new prediction method and thoroughly assessed its performance via cross-validation and independent dataset test. The results show that our method achieves higher prediction performance than well-known methods such as Robetta, FoldX and Hotpoint. We conclude that these contact descriptors, in particular the novel co-occurring atomic contacts, can be used to facilitate accurate and interpretable characterization of protein binding hot spots. PMID:26675422

  9. Infrared sensor for hot spot recognition for a small satellite mission

    NASA Astrophysics Data System (ADS)

    Skrbek, W.; Bachmann, K.; Lorenz, E.; Neidhardt, M.; Peschel, M.; Walter, I.; Zender, B.

    1996-11-01

    High temperature events strongly influence the environmental processes. Therefore, their observation is an important constituent of the global monitoring network. Unfortunately the current remote sensing systems are not able to deliver the necessary information about the world wide burn out of vegetation and its consequences. For global observations a dedicated system of small satellites is required. The main components of the corresponding instrumentation are the infrared channels. The proposed HSRS (HOT SPOT RECOGNITION SENSOR) has to demonstrate the possibilities of an such instrumentation and its feasibility for small satellites. The main drawbacks of the HSRS design are the handling of the hot spot recognition in the subpixel area and of the saturation in the case of larger hot areas by a suitable signal processing hardware.

  10. DBAC: A simple prediction method for protein binding hot spots based on burial levels and deeply buried atomic contacts

    PubMed Central

    2011-01-01

    Background A protein binding hot spot is a cluster of residues in the interface that are energetically important for the binding of the protein with its interaction partner. Identifying protein binding hot spots can give useful information to protein engineering and drug design, and can also deepen our understanding of protein-protein interaction. These residues are usually buried inside the interface with very low solvent accessible surface area (SASA). Thus SASA is widely used as an outstanding feature in hot spot prediction by many computational methods. However, SASA is not capable of distinguishing slightly buried residues, of which most are non hot spots, and deeply buried ones that are usually inside a hot spot. Results We propose a new descriptor called “burial level” for characterizing residues, atoms and atomic contacts. Specifically, burial level captures the depth the residues are buried. We identify different kinds of deeply buried atomic contacts (DBAC) at different burial levels that are directly broken in alanine substitution. We use their numbers as input for SVM to classify between hot spot or non hot spot residues. We achieve F measure of 0.6237 under the leave-one-out cross-validation on a data set containing 258 mutations. This performance is better than other computational methods. Conclusions Our results show that hot spot residues tend to be deeply buried in the interface, not just having a low SASA value. This indicates that a high burial level is not only a necessary but also a more sufficient condition than a low SASA for a residue to be a hot spot residue. We find that those deeply buried atoms become increasingly more important when their burial levels rise up. This work also confirms the contribution of deeply buried interfacial atomic contacts to the energy of protein binding hot spot. PMID:21689480

  11. Stress analysis for wall structure in mobile hot cell design

    SciTech Connect

    Bahrin, Muhammad Hannan Rahman, Anwar Abdul Hamzah, Mohd Arif Mamat, Mohd Rizal; Azman, Azraf; Hasan, Hasni

    2016-01-22

    Malaysian Nuclear Agency is developing a Mobile Hot Cell (MHC) in order to handle and manage Spent High Activity Radioactive Sources (SHARS) such as teletherapy heads and irradiators. At present, there are only two units of MHC in the world, in South Africa and China. Malaysian Mobile Hot cell is developed by Malaysian Nuclear Agency with the assistance of IAEA expert, based on the design of South Africa and China, but with improved features. Stress analysis has been performed on the design in order to fulfil the safety requirement in operation of MHC. This paper discusses the loading analysis effect from the sand to the MHC wall structure.

  12. Newberry Volcano, Oregon: No traveling hot spot is needed

    NASA Astrophysics Data System (ADS)

    Donnelly-Nolan, J. M.

    2009-12-01

    Newberry Volcano (NV) has been interpreted as forming the end of the traveling “Newberry Hot Spot” responsible for producing progressively younger rhyolites as it passed westward under the High Lava Plains (HLP). However, Newberry rhyolites are unlike those to the east in the HLP. HLP rhyolites are characterized by high silica (>74%) and high FeO (Ford et al., 2009 GSA abs.). None of the Holocene Newberry rhyolites and only a few of its older rhyolites have such high silica contents. The NV rhyolites have low FeO contents comparable to those of rhyolites to the west near the Cascades axis. NV is situated at the western edge of the HLP (a subprovince of the Basin & Range) east of the Cascades arc axis, its broad shield shape in striking contrast to typical Cascades stratocones. Isotopic and petrologic evidence (Graham et al., JVGR 2009; Carlson et al., 2008 Goldschmidt abs.; Grove et al, 2009 GSA abs.) indicate that Newberry lava compositions are unlike HLP lavas, and instead include a strong input of subduction fluid. The shape, size, and rear-arc position of NV are like those of Medicine Lake volcano (MLV) east of Mount Shasta in northern California, also often misinterpreted as a Basin & Range volcano. Newberry is even larger than the 2000 km2 MLV. In fewer than half a million years, NV has built a km-high edifice, suffered at least 3 caldera collapses, and its lavas have covered approximately 3000 km2, making it the largest of any Cascade volcano. At both NV and MLV, the central caldera is situated over the intersection of major tectonic trends. The widespread distribution of vents and their dominant NE to NW trends at both volcanoes attest to tectonic control of eruptive pathways and to broad magmatic foci. Fluids are required to generate the calcalkaline basalts present at both volcanoes (especially NV) in addition to tholeiitic basalts. Hydrous arc magmatic inputs also play a key role at both NV and MLV in generation of significant volumes of rhyolite and

  13. Analysis of Biological Features Associated with Meiotic Recombination Hot and Cold Spots in Saccharomyces cerevisiae

    PubMed Central

    Hansen, Loren; Kim, Nak-Kyeong; Mariño-Ramírez, Leonardo; Landsman, David

    2011-01-01

    Meiotic recombination is not distributed uniformly throughout the genome. There are regions of high and low recombination rates called hot and cold spots, respectively. The recombination rate parallels the frequency of DNA double-strand breaks (DSBs) that initiate meiotic recombination. The aim is to identify biological features associated with DSB frequency. We constructed vectors representing various chromatin and sequence-based features for 1179 DSB hot spots and 1028 DSB cold spots. Using a feature selection approach, we have identified five features that distinguish hot from cold spots in Saccharomyces cerevisiae with high accuracy, namely the histone marks H3K4me3, H3K14ac, H3K36me3, and H3K79me3; and GC content. Previous studies have associated H3K4me3, H3K36me3, and GC content with areas of mitotic recombination. H3K14ac and H3K79me3 are novel predictions and thus represent good candidates for further experimental study. We also show nucleosome occupancy maps produced using next generation sequencing exhibit a bias at DSB hot spots and this bias is strong enough to obscure biologically relevant information. A computational approach using feature selection can productively be used to identify promising biological associations. H3K14ac and H3K79me3 are novel predictions of chromatin marks associated with meiotic DSBs. Next generation sequencing can exhibit a bias that is strong enough to lead to incorrect conclusions. Care must be taken when interpreting high throughput sequencing data where systematic biases have been documented. PMID:22242140

  14. Multistable dissipative structures pinned to dual hot spots

    NASA Astrophysics Data System (ADS)

    Tsang, Cheng Hou; Malomed, Boris A.; Chow, Kwok Wing

    2011-12-01

    We analyze the formation of one-dimensional localized patterns in a nonlinear dissipative medium including a set of two narrow “hot spots” (HSs), which carry the linear gain, local potential, cubic self-interaction, and cubic loss, while the linear loss acts in the host medium. This system can be realized as a spatial-domain one in optics and also in Bose-Einstein condensates of quasiparticles in solid-state settings. Recently, exact solutions were found for localized modes pinned to the single HS represented by the δ function. The present paper reports analytical and numerical solutions for coexisting two- and multipeak modes, which may be symmetric or antisymmetric with respect to the underlying HS pair. Stability of the modes is explored through simulations of their perturbed evolution. The sign of the cubic nonlinearity plays a crucial role: in the case of the self-focusing, only the fundamental symmetric and antisymmetric modes, with two local peaks tacked to the HSs, and no additional peaks between them, may be stable. In this case, all the higher-order multipeak modes, being unstable, evolve into the fundamental ones. Stability regions for the fundamental modes are reported. A more interesting situation is found in the case of the self-defocusing cubic nonlinearity, with the HS pair giving rise to a multistability, with up to eight coexisting stable multipeak patterns, symmetric and antisymmetric ones. The system without the self-interaction, the nonlinearity being represented only by the local cubic loss, is investigated too. This case is similar to those with the self-focusing or defocusing nonlinearity, if the linear potential of the HS is, respectively, attractive or repulsive. An additional feature of the former setting is the coexistence of the stable fundamental modes with robust breathers.

  15. Cassini VIMS Spectra of the Thermal Emission from Hot Spots Along Enceladus South Pole Fissures

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Cassini VIMS Team

    2016-10-01

    Most of the south pole fissure region has not been directly illuminated by sunlight since the sub-solar point moved into the northern hemisphere in 2009, thereby eliminating the background of reflected sunlight at VIMS wavelengths and making the fissure thermal emission readily measureable. Since then, VIMS has measured spectra of at least 11 hot spots along the fissures. Most of these measurements were acquired in ride-along mode with CIRS as the prime instrument. During at least 2 encounters, VIMS and CIRS acquired simultaneous or near-simultaneous spectra of the same fissure location. VIMS spectra include multiple hot spots along Damascus, Baghdad, Cairo, and a likely hot spot on Alexandria.All of the VIMS spectra examined to date are consistent with this scenario of a self-regulating fissure maximum T~200 K with brighter VIMS emissions corresponding to fissures up to ~20 m wide. Emission from the warm fissure interior walls dominate the VIMS spectra with <15% contributed by conductive heating of the adjacent terrain at VIMS wavelengths.CIRS spectra report slightly cooler T's due to CIRS increased sensitivity to lower T emission at longer wavelengths and averaging over contributions from both the hottest and cooler areas. Combined analysis of the CIRS and VIMS spectra spanning 3 to 500 micron wavelengths promises to reveal the distribution of [T, area] near the fissures that cannot be spatially resolved. This [T, area] distribution holds the key to understanding how heat is transferred to the surface within a few 100 m of the fissures.The VIMS-detected emission is concentrated in localized hot spots along the fissures and does not seem to be distributed continuously along them. CIRS spectra suggest a more continuous distribution of the emission along the fissure length. Jets locations also are distributed along the fissure length and it appears that the VIMS-detected hot spots in general correlate with jet locations, but not all of the jet locations have been

  16. Structural basis for human PRDM9 action at recombination hot spots.

    PubMed

    Patel, Anamika; Horton, John R; Wilson, Geoffrey G; Zhang, Xing; Cheng, Xiaodong

    2016-02-01

    The multidomain zinc finger (ZnF) protein PRDM9 (PRD1-BF1-RIZ1 homologous domain-containing 9) is thought to influence the locations of recombination hot spots during meiosis by sequence-specific DNA binding and trimethylation of histone H3 Lys4. The most common variant of human PRDM9, allele A (hPRDM9A), recognizes the consensus sequence 5'-NCCNCCNTNNCCNCN-3'. We cocrystallized ZnF8-12 of hPRDM9A with an oligonucleotide representing a known hot spot sequence and report the structure here. ZnF12 was not visible, but ZnF8-11, like other ZnF arrays, follows the right-handed twist of the DNA, with the α helices occupying the major groove. Each α helix makes hydrogen-bond (H-bond) contacts with up to four adjacent bases, most of which are purines of the complementary DNA strand. The consensus C:G base pairs H-bond with conserved His or Arg residues in ZnF8, ZnF9, and ZnF11, and the consensus T:A base pair H-bonds with an Asn that replaces His in ZnF10. Most of the variable base pairs (N) also engage in H bonds with the protein. These interactions appear to compensate to some extent for changes from the consensus sequence, implying an adaptability of PRDM9 to sequence variations. We investigated the binding of various alleles of hPRDM9 to different hot spot sequences. Allele C was found to bind a C-specific hot spot with higher affinity than allele A bound A-specific hot spots, perhaps explaining why the former is dominant in A/C heterozygotes. Allele L13 displayed higher affinity for several A-specific sequences, allele L9/L24 displayed lower affinity, and allele L20 displayed an altered sequence preference. These differences can be rationalized structurally and might contribute to the variation observed in the locations and activities of meiotic recombination hot spots.

  17. Structural basis for human PRDM9 action at recombination hot spots

    PubMed Central

    Patel, Anamika; Horton, John R.; Wilson, Geoffrey G.; Zhang, Xing; Cheng, Xiaodong

    2016-01-01

    The multidomain zinc finger (ZnF) protein PRDM9 (PRD1–BF1–RIZ1 homologous domain-containing 9) is thought to influence the locations of recombination hot spots during meiosis by sequence-specific DNA binding and trimethylation of histone H3 Lys4. The most common variant of human PRDM9, allele A (hPRDM9A), recognizes the consensus sequence 5′-NCCNCCNTNNCCNCN-3′. We cocrystallized ZnF8–12 of hPRDM9A with an oligonucleotide representing a known hot spot sequence and report the structure here. ZnF12 was not visible, but ZnF8–11, like other ZnF arrays, follows the right-handed twist of the DNA, with the α helices occupying the major groove. Each α helix makes hydrogen-bond (H-bond) contacts with up to four adjacent bases, most of which are purines of the complementary DNA strand. The consensus C:G base pairs H-bond with conserved His or Arg residues in ZnF8, ZnF9, and ZnF11, and the consensus T:A base pair H-bonds with an Asn that replaces His in ZnF10. Most of the variable base pairs (N) also engage in H bonds with the protein. These interactions appear to compensate to some extent for changes from the consensus sequence, implying an adaptability of PRDM9 to sequence variations. We investigated the binding of various alleles of hPRDM9 to different hot spot sequences. Allele C was found to bind a C-specific hot spot with higher affinity than allele A bound A-specific hot spots, perhaps explaining why the former is dominant in A/C heterozygotes. Allele L13 displayed higher affinity for several A-specific sequences, allele L9/L24 displayed lower affinity, and allele L20 displayed an altered sequence preference. These differences can be rationalized structurally and might contribute to the variation observed in the locations and activities of meiotic recombination hot spots. PMID:26833727

  18. Legal space for syringe exchange programs in hot spots of injection drug use-related crime.

    PubMed

    Allen, Sean T; Ruiz, Monica S; Jones, Jeff; Turner, Monique M

    2016-04-26

    Copious evidence indicates that syringe exchange programs (SEPs) are effective structural interventions for HIV prevention among persons who inject drugs (PWID). The efficacy of SEPs in supporting the public health needs of PWID populations is partially dependent on their accessibility and consistent utilization among injectors. Research has shown that SEP access is an important predictor of PWID retention at SEPs, yet policies exist that may limit the geographic areas where SEP operations may legally occur. Since 2000 in the District of Columbia (DC), SEP operations have been subject to the 1000 Foot Rule (§48-1121), a policy that prohibits the distribution of "any needle or syringe for the hypodermic injection of any illegal drug in any area of the District of Columbia which is within 1000 feet of a public or private elementary or secondary school (including a public charter school)." The 1000 Foot Rule may impede SEP services in areas that are in urgent need for harm reduction services, such as locations where injections are happening in "real time" or where drugs are purchased or exchanged. We examined the effects of the 1000 Foot Rule on SEP operational space in injection drug use (IDU)-related crime (i.e., heroin possession or distribution) hot spots from 2000 to 2010. Data from the DC Metropolitan Police Department were used to identify IDU-related crime hot spots. School operation data were matched to a dataset that described the approximate physical property boundaries of land parcels. A 1000-ft buffer was applied to all school property boundaries. The overlap between the IDU-related crime hot spots and the school buffer zones was calculated by academic year. When overlaying the land space associated with IDU-related crime hot spots on the maps of school boundaries per the 1000-ft buffer zone stipulation, we found that the majority of land space in these locations was ineligible for legal SEP operations. More specifically, the ineligible space in the

  19. High-temperature hot spots on Io as seen by the Galileo solid state imaging (SSI) experiment

    USGS Publications Warehouse

    McEwen, A.S.; Simonelli, D.P.; Senske, D.R.; Klaasen, K.P.; Keszthelyi, L.; Johnson, T.V.; Geissler, P.E.; Carr, M.H.; Belton, M.J.S.

    1997-01-01

    High-temperature hot spots on Io have been imaged at ???50 km spatial resolution by Galileo's CCD imaging system (SSI). Images were acquired during eclipses (Io in Jupiter's shadow) via the SSI clear filter (???0.4-1.0 ??m), detecting emissions from both small intense hot spots and diffuse extended glows associated with Io's atmosphere and plumes. A total of 13 hot spots have been detected over ???70% of Io's surface. Each hot spot falls precisely on a low-albedo feature corresponding to a caldera floor and/or lava flow. The hot-spot temperatures must exceed ???700 K for detection by SSI. Observations at wavelengths longer than those available to SSI require that most of these hot spots actually have significantly higher temperatures (???1000 K or higher) and cover small areas. The high-temperature hot spots probably mark the locations of active silicate volcanism, supporting suggestions that the eruption and near-surface movement of silicate magma drives the heat flow and volcanic activity of Io. Copyright 1997 by the American Geophysical Union.

  20. 40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CO, PM10, and PM2.5 concentrations (hot-spot analysis). 93.123 Section 93.123 Protection of.... or the Federal Transit Laws § 93.123 Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis). (a) CO hot-spot analysis. (1) The demonstrations required by §...

  1. 40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CO, PM10, and PM2.5 concentrations (hot-spot analysis). 93.123 Section 93.123 Protection of.... or the Federal Transit Laws § 93.123 Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis). (a) CO hot-spot analysis. (1) The demonstrations required by §...

  2. 40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CO, PM10, and PM2.5 concentrations (hot-spot analysis). 93.123 Section 93.123 Protection of.... or the Federal Transit Laws § 93.123 Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis). (a) CO hot-spot analysis. (1) The demonstrations required by §...

  3. 40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CO, PM10, and PM2.5 concentrations (hot-spot analysis). 93.123 Section 93.123 Protection of.... or the Federal Transit Laws § 93.123 Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis). (a) CO hot-spot analysis. (1) The demonstrations required by §...

  4. Location of hot spots in integrated circuits by monitoring the substrate thermal-phase lag with the mirage effect.

    PubMed

    Perpiñà, Xavier; Altet, Josep; Jordà, Xavier; Vellvehi, Miquel; Mestres, Narcís

    2010-08-01

    This Letter presents a solution for locating hot spots in active integrated circuits (IC) and devices. This method is based on sensing the phase lag between the power periodically dissipated by a device integrated in an IC (hot spot) and its corresponding thermal gradient into the chip substrate by monitoring the heat-induced refractive index gradient with a laser beam. The experimental results show a high accuracy and prove the suitability of this technique to locate and characterize devices behaving as hot spots in current IC technologies.

  5. "Rings of saturn-like" nanoarrays with high number density of hot spots for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Dai, Zhigao; Mei, Fei; Xiao, Xiangheng; Liao, Lei; Fu, Lei; Wang, Jiao; Wu, Wei; Guo, Shishang; Zhao, Xinyue; Li, Wei; Ren, Feng; Jiang, Changzhong

    2014-07-01

    The Ag nanoparticles (NPs) surrounding triangular nanoarrays (TNAs) with high number density of surface-enhanced Raman scattering (SERS) hot spots (SERS hot spots ring) are prepared by a combination of NPs deposition and subsequent colloid lithography processing. Owing to the SERS hot spots ring, the Ag NPs surrounding TNAs have been proved an excellent candidate for ultrasensitive molecular sensing for their high SERS signal enhancing capacity in experiments and theories. The Ag NPs surrounding TNAs can be readily used for the quick detection of low concentrations of molecules related to food safety; herein, detection of melamine is discussed.

  6. Hot-spot contributions in shocked high explosives from mesoscale ignition models

    NASA Astrophysics Data System (ADS)

    Levesque, G.; Vitello, P.; Howard, W. M.

    2013-06-01

    High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

  7. Influence of hot spot features on the initiation characteristics of heterogeneous nitromethane

    SciTech Connect

    Dattelbaum, Dana M; Sheffield, Stephen A; Stahl, David B; Dattelbaum, Andrew M; Engelke, Ray

    2010-01-01

    To gain insights into the critical hot spot features influencing energetic materials initiation characteristics, well-defined micron-scale particles have been intentionally introduced into the homogeneous explosive nitromethane (NM). Two types of potential hot spot origins have been examined - shock impedance mismatches using solid silica beads, and porosity using hollow microballoons - as well as their sizes and inter-particle separations. Here, we present the results of several series of gas gun-driven plate impact experiments on NM/particle mixtures with well-controlled shock inputs. Detailed insights into the nature of the reactive flow during the build-up to detonation have been obtained from the response of in-situ electromagnetic gauges, and the data have been used to establish Pop-plots (run-distance-to-detonation vs. shock input pressure) for the mixtures. Comparisons of sensitization effects and energy release characteristics relative to the initial shock front between the solid and hollow beads are presented.

  8. Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots

    PubMed Central

    Alonso-González, P.; Albella, P.; Schnell, M.; Chen, J.; Huth, F.; García-Etxarri, A.; Casanova, F.; Golmar, F.; Arzubiaga, L.; Hueso, L.E.; Aizpurua, J.; Hillenbrand, R.

    2012-01-01

    Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering. PMID:22353715

  9. Spatial and temporal variability of sea level rise hot spots over the eastern United States

    NASA Astrophysics Data System (ADS)

    Valle-Levinson, Arnoldo; Dutton, Andrea; Martin, Jonathan B.

    2017-08-01

    Regional sea level rise (SLR) acceleration during the past few decades north of Cape Hatteras has commonly been attributed to weakening Atlantic Meridional Overturning Circulation, although this causal link remains debated. In contrast to this pattern, we demonstrate that SLR decelerated north of Cape Hatteras and accelerated south of the Cape to >20 mm/yr, > 3 times the global mean values from 2011 to 2015. Tide gauge records reveal comparable short-lived, rapid SLR accelerations (hot spots) that have occurred repeatedly over 1500 km stretches of the coastline during the past 95 years, with variable latitudinal position. Our analysis indicates that the cumulative (time-integrated) effects of the North Atlantic Oscillation determine the latitudinal position of these SLR hot spots, while a cumulative El Niño index is associated with their timing. The superposition of these two ocean-atmospheric processes accounts for 87% of the variance in the spatiotemporal pattern of intradecadal sea level oscillations.

  10. Rapid experimental SAD phasing and hot-spot identification with halogenated fragments

    SciTech Connect

    Bauman, Joseph D.; Harrison, Jerry Joe E. K.; Arnold, Eddy

    2016-01-01

    Through X-ray crystallographic fragment screening, 4-bromopyrazole was discovered to be a `magic bullet' that is capable of binding at many of the ligand `hot spots' found in HIV-1 reverse transcriptase (RT). The binding locations can be in pockets that are `hidden' in the unliganded crystal form, allowing rapid identification of these sites forin silicoscreening. In addition to hot-spot identification, this ubiquitous yet specific binding provides an avenue for X-ray crystallographic phase determination, which can be a significant bottleneck in the determination of the structures of novel proteins. The anomalous signal from 4-bromopyrazole or 4-iodopyrazole was sufficient to determine the structures of three proteins (HIV-1 RT, influenza A endonuclease and proteinase K) by single-wavelength anomalous dispersion (SAD) from single crystals. Both compounds are inexpensive, readily available, safe and very soluble in DMSO or water, allowing efficient soaking into crystals.

  11. A DLR small satellite mission for the investigation of hot spots, vegetation and clouds

    NASA Astrophysics Data System (ADS)

    Brieβ, K.; Jahn, H.; Röser, H. P.

    1996-11-01

    Starting from their FIRES proposal [1]the DLR makes a new approach in the design of a small satellite mission dedicated to hot spot detection and evaluation: the BIRD mission. The new approach is characterized by a strict design-to-cost philosophy. A two-channel infrared sensor system in combination with a Wide-Angle Optoelectronic Stereo Scanner (WAOSS) shall be the payload of a small satellite (80kg) considered for piggyback launch. So the launch is not a main cost driver as for other small satellite missions with dedicated launchers. The paper describes the mission objectives, the scientific payload, the spacecraft bus, and the mission architecture of a small satellite mission dedicated to the investigation of hot spots (forest fires, volcanic activities, burning oil wells or coal seams), of vegetation condition and changes and of clouds. The paper represents some results of a phase A study and of the progressing phase B.

  12. Mantle shear-wave velocity structure beneath the Hawaiian hot spot.

    PubMed

    Wolfe, Cecily J; Solomon, Sean C; Laske, Gabi; Collins, John A; Detrick, Robert S; Orcutt, John A; Bercovici, David; Hauri, Erik H

    2009-12-04

    Defining the mantle structure that lies beneath hot spots is important for revealing their depth of origin. Three-dimensional images of shear-wave velocity beneath the Hawaiian Islands, obtained from a network of sea-floor and land seismometers, show an upper-mantle low-velocity anomaly that is elongated in the direction of the island chain and surrounded by a parabola-shaped high-velocity anomaly. Low velocities continue downward to the mantle transition zone between 410 and 660 kilometers depth, a result that is in agreement with prior observations of transition-zone thinning. The inclusion of SKS observations extends the resolution downward to a depth of 1500 kilometers and reveals a several-hundred-kilometer-wide region of low velocities beneath and southeast of Hawaii. These images suggest that the Hawaiian hot spot is the result of an upwelling high-temperature plume from the lower mantle.

  13. Timing of hot spot--related volcanism and the breakup of madagascar and India.

    PubMed

    Storey, M; Mahoney, J J; Saunders, A D; Duncan, R A; Kelley, S P; Coffin, M F

    1995-02-10

    Widespread basalts and rhyolites were erupted in Madagascar during the Late Cretaceous. These are considered to be related to the Marion hot spot and the breakup of Madagascar and Greater India. Seventeen argon-40/argon-39 age determinations reveal that volcanic rocks and dikes from the 1500-kilometer-long rifted eastern margin of Madagascar were emplaced rapidly (mean age = 87.6 +/- 0.6 million years ago) and that the entire duration of Cretaceous volcanism on the island was no more than 6 million years. The evidence suggests that the thick lava pile at Volcan de l'Androy in the south of the island marks the focal point of the Marion hot spot at approximately 88 million years ago and that this mantle plume was instrumental in causing continental breakup.

  14. Mesoscopic description of hot spot phenomena: a route for hybrid multiscale simulations

    NASA Astrophysics Data System (ADS)

    Maillet, Jean-Bernard

    2015-06-01

    We describe large scale simulations of hot spot phenomena in single TATB crystals within the DPDE framework. The mesoscopic DPDE model is calibrated on all atom simulations, and particular attention is given to the rate of heat exchange between intramolecular and intermolecular degrees of freedom, which control the non-equilibrium behaviour of the system. Simulations of pore collapse at different shock speeds and for different pore sizes are performed, and a criterium for the quantification of the hot spot energy is proposed. These results are considered as reference data for subsequent comparison with top down simulations of similar processes. We present a reformulation of the (hydrodynamic) SDPD method allowing a direct coupling with the DPDE model, then opening the route for hybrid multiscale simulations.

  15. Fluorescence Enhancement of Nanoraspberry Hot-spot Source Composed of Gold Nanoparticles and Aniline Oligomers.

    PubMed

    Kinoshita, Takamasa; Nguyen, Dung Quang; Nishino, Tomoaki; Nakao, Hidenobu; Shiigi, Hiroshi; Nagaoka, Tsutomu

    2015-01-01

    In this study, we examined raspberry-shaped organic/inorganic hybrid structure for potential development of a nanoantenna system capable of detecting and labeling biomolecules. The structure is characterized by a high density of gold nanoparticles (AuNPs) separated by closely packed aniline oligomers that serve as a linkage between adjacent particles. In particular, the structure was based on repeated sequences of AuNP-aniline oligomer-AuNP in a three-dimensional arrangement, which enabled the creation of optical hot spots that can hold multiple molecules. We examine the expression of such features by focusing on the structure and characteristics of the hybrid. We demonstrate that these optical hot spots enhance the dye fluorescence without quenching. As a result, we were able to create a nanoantenna structure enabling the efficient use of light.

  16. ELIPGRID-PC: A PC program for calculating hot spot probabilities

    SciTech Connect

    Davidson, J.R.

    1994-10-01

    ELIPGRID-PC, a new personal computer program has been developed to provide easy access to Singer`s 1972 ELIPGRID algorithm for hot-spot detection probabilities. Three features of the program are the ability to determine: (1) the grid size required for specified conditions, (2) the smallest hot spot that can be sampled with a given probability, and (3) the approximate grid size resulting from specified conditions and sampling cost. ELIPGRID-PC also provides probability of hit versus cost data for graphing with spread-sheets or graphics software. The program has been successfully tested using Singer`s published ELIPGRID results. An apparent error in the original ELIPGRID code has been uncovered and an appropriate modification incorporated into the new program.

  17. Identifying fish diversity hot-spots in data-poor situations.

    PubMed

    Fonseca, Vinícius Prado; Pennino, Maria Grazia; de Nóbrega, Marcelo Francisco; Oliveira, Jorge Eduardo Lins; de Figueiredo Mendes, Liana

    2017-08-01

    One of the more challenging tasks in Marine Spatial Planning (MSP) is identifying critical areas for management and conservation of fish stocks. However, this objective is difficult to achieve in data-poor situations with different sources of uncertainty. In the present study we propose a combination of hierarchical Bayesian spatial models and remotely sensed estimates of environmental variables to be used as flexible and reliable statistical tools to identify and map fish species richness and abundance hot-spots. Results show higher species aggregates in areas with higher sea floor rugosity and habitat complexity, and identify clear richness hot-spots. Our findings identify sensitive habitats through essential and easy-to-use interpretation tools, such as predictive maps, which can contribute to improving management and operability of the studied data-poor situations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Star Spot Activities of Solar-type Stars with Hot-Jupiters in Kepler Data

    NASA Astrophysics Data System (ADS)

    Huang, Li-Ching; Ip, Wing-Huen; Wu, Chi-Ju

    2014-05-01

    The long-term observations of the Kepler space telescope provided high precision time-series photometric measurements of more than 160,000 stars in a 115-square-degree field near Cygnus and Lyra. More than 2,000 exoplanet candidates orbiting around Solar-type stars have been found. Among them 15 are hot-Jupiters, which might have strong star-planet interaction. In this study, we analysed the short cadence (1 minute) lightcurve data of Kepler-17, Kepler-41, and Kepler-43 that are G-type main-sequence stars each with a hot-Jupiter. The masses of the host stars are 1.16 Msun, 0.94Msun, and 1.19 Msun, respectively. The masses of the hot-Jupiters around them are 2.45 MJ (Jovian mass), 0.49MJ, and 3.23 MJ, and the orbital periods are 1.48 d, 1.85 d and 3.02 d, respectively. The orbital planes of these hot-Jupiters are all within 10 degrees of the line-of-sight. (Santerne et al. 2011 and Bonomo et al. 2012) Kepler-17 showed strong magnetic activity of which the star spot coverage could be as much as 5% of the hemispherical area. The other two have smaller spot sizes (~ 0.5% of stellar hemispherical area). We have examined their lightcurves to check whether they exhibit flare activities over the time interval of the Kepler measurements (2009~2013). That none was found is consistent with the report by Shibata et al. (2012). We examined the variations in the hot-Jupiter transiting lightcurves to measure the spot size and location in detail. The statistical data can be used to infer the migration process of the star spots across the stellar disk. The large size of its spots means that Kepler-17 should have frequent occurrence of superflares. The absence of superflare activity is therefore puzzling. The possible energy dissipation effect of coronal magnetic field interaction with the hot-Jupiter (Kepler-17b) is discussed in the study. [References] Bonomo, A. S., Hebrard, G., Santerne, A., et al. 2012, A&A, 538, A96 Bonomo, A. S. and Lanza, A. F. 2012, A&A, 547, A37 Santerne, A

  19. Description of ’Hot Spots’ Associated with Localized Shear Zones in Impact Tests

    DTIC Science & Technology

    1981-10-21

    NSWC CR 80-499 TO 00 DESCRIPTION OF "HOT SPOTS" ASSOCIATED WITH LOCALIZED SHEAR ZONES IN IMPACT TESTS BY C. STEPHEN COFFEY RONALD W. ARMSTRONG...different slip system geometries or other microstructural characteristics. Sugar, for instance, shows darkening directly under the original crystal site but...heating on promoting premature failure of high strength ferritic steel in torsion has been examined at different strain rates. 2 At a torsional shear

  20. Elucidation of the Dynamics for Hot-Spot Initiation at Nonuniform Interfaces of Highly Shocked Materials

    DTIC Science & Technology

    2011-12-07

    to examine the effect of shocks on realistic models of polymer-bonded explosives, where we use these simulations to extract the mechanism of hot-spot...simulation cell and time interval is far beyond the capabilities of current quantum mechanics (QM) methods but can be treated using the QM- based ...using HTPB - and isophorone diisocyanate (IPDI)- based polyurethane rubber. HTPB (see Fig. S1 of the Supplemental Material18) is a copolymer, containing

  1. {open_quote}{open_quote}Hot spots{close_quote}{close_quote} effect in nuclear shadowing

    SciTech Connect

    Zhu, W.; Ruan, J. |

    1996-07-01

    Shadowing in inelastic lepton-nucleus scattering is analyzed by using the modified Gribov-Levin-Ryskin evolution equation. We find that a comparison of the structure functions between nuclear and proton targets at {ital x}{lt}10{sup {minus}3} and {ital Q}{sup 2}{approx_gt}1 GeV{sup 2} can provide useful information about the hot spots of the nucleon. {copyright} {ital 1996 The American Physical Society.}

  2. Analysis of binding site hot spots on the surface of Ras GTPase.

    PubMed

    Buhrman, Greg; O'Connor, Casey; Zerbe, Brandon; Kearney, Bradley M; Napoleon, Raeanne; Kovrigina, Elizaveta A; Vajda, Sandor; Kozakov, Dima; Kovrigin, Evgenii L; Mattos, Carla

    2011-11-04

    We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the "off" and "on" allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Analysis of Binding Site Hot Spots on the Surface of Ras GTPase

    PubMed Central

    Buhrman, Greg; O’Connor, Casey; Zerbe, Brandon; Kearney, Bradley M.; Napoleon, Raeanne; Kovrigina, Elizaveta A.; Vajda, Sandor; Kozakov, Dima; Kovrigin, Evgenii L.; Mattos, Carla

    2011-01-01

    We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the “off” and “on” allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target. PMID:21945529

  4. Hot spots in the inboard section of the TFCX toroidal field coils

    SciTech Connect

    Yang, S.; Gohar, Y.

    1985-01-01

    The TFCX conceptual designs call for the construction of the reactor torus through the use of ''pie-shaped'' segments for mechanical and maintenance considerations. The use of this concept results in hot spots in the inboard section of the torodial field (TF) coils due to neutron and photon streaming through the slots between the segments. This work studies these effects on the nuclear responses in the TF coils and introduces design solutions to reduce the impact on the reactor design.

  5. Hot-Spot Fatigue and Impact Damage Detection on a Helicopter Tailboom

    DTIC Science & Technology

    2011-09-01

    technology, a thin dielectric film with an array of durable , networked piezoelectric sensors, monitors the integrity of the composite and metal...Crack Monitoring There were a total of 28 PZT disks that were mounted on the tailboom for testing: 14 of them were used as actuators, while the...other 14 PZT disks were used as sensors. Among the 28 PZT disks, 16 PZT disks were placed in the two fatigue hot-spot areas to detect cracks initiated

  6. Hot-Spot Avoidance With Multi-Pathing Over Infiniband: An MPI Perspective

    SciTech Connect

    Vishnu, A; Koop, M; Moody, A; Mamidala, A R; Narravula, S; Panda, D K

    2007-03-06

    Large scale InfiniBand clusters are becoming increasingly popular, as reflected by the TOP 500 Supercomputer rankings. At the same time, fat tree has become a popular interconnection topology for these clusters, since it allows multiple paths to be available in between a pair of nodes. However, even with fat tree, hot-spots may occur in the network depending upon the route configuration between end nodes and communication pattern(s) in the application. To make matters worse, the deterministic routing nature of InfiniBand limits the application from effective use of multiple paths transparently and avoid the hot-spots in the network. Simulation based studies for switches and adapters to implement congestion control have been proposed in the literature. However, these studies have focused on providing congestion control for the communication path, and not on utilizing multiple paths in the network for hot-spot avoidance. In this paper, we design an MPI functionality, which provides hot-spot avoidance for different communications, without a priori knowledge of the pattern. We leverage LMC (LID Mask Count) mechanism of InfiniBand to create multiple paths in the network and present the design issues (scheduling policies, selecting number of paths, scalability aspects) of our design. We implement our design and evaluate it with Pallas collective communication and MPI applications. On an InfiniBand cluster with 48 processes, collective operations like MPI All-to-all Personalized and MPI Reduce Scatter show an improvement of 27% and 19% respectively. Our evaluation with MPI applications like NAS Parallel Benchmarks and PSTSWM on 64 processes shows significant improvement in execution time with this functionality.

  7. Aquatic Ecosystem Exposure Associated with Atmospheric Mercury Deposition: Importance of Watershed and Water Body Hot Spots and Hot Moments

    NASA Astrophysics Data System (ADS)

    Knightes, C. D.; Golden, H. E.

    2008-12-01

    Atmospheric deposition of divalent mercury (Hg(II)) is the often the primary driving force for mercury contamination in fish tissue, resulting in mercury exposure to wildlife and humans. In lake systems associated with small watersheds, direct deposition to the water surface is typically the dominant mercury loading source; however, in lake systems with large watersheds and river systems, these inputs may be relatively small compared to loadings from the watershed via erosion and surface runoff. Within each system, transformation of the deposited mercury into the environmentally relevant form, methylmercury (MeHg), proceeds at different rates largely regulated by physical characteristics such as watershed land use types and water body hydraulic residence times, as water body chemistry, such as pH and trophic status Therefore, to fully represent mercury exposure in aquatic ecosystems, we must couple watershed models with water body models and explore where, why, and when hot spots and hot moments of transformation and transport occur. Here we link the simulated atmospheric mercury deposition results from the Community Multi-Scale Air Quality (CMAQ) model, a spatially distributed grid-based watershed mercury (Hg) model (GBMM), and the Water Quality Analysis Simulation Program (WASP). We use this multi-media modeling framework to simulate mercury species cycling over time for the different river reaches and watersheds within the Cape Fear River Basin, North Carolina. Through these simulations we investigate the importance of specific watershed and surface water system characteristics in simulating MeHg exposure concentrations. Because GBMM is a spatially-distributed model we are able to investigate the importance of such factors (i.e., watershed area, land-use types, and land-use percentages) in transporting and transforming deposited mercury. We present how particular land-use types and land-use change influence total loading and total mercury concentrations, how

  8. Characterizing Denitrification Hot Spots and Hot Moments to Improve Understanding in a Mass Balance Approach to the Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Morris, C. K.; Barclay, J. R.; Anderson, T. R.; Walter, M. T.

    2013-12-01

    Several transformation processes of the nitrogen cycle control the availability of this primary nutrient to living organisms. Understanding the multiple processes that take place in the vadose zone is critical to developing management strategies, predicting air and aquatic impacts, and maximizing functionality of landscapes. The mass balance approach to studying the nitrogen cycle is useful in quantifying rates of these processes. In combination with field measurements, hypotheses about the rates of difficult-to-measure processes such as denitrification (DN), can be tested. In this study we extend the mass balance approach to investigate the significance of DN hot spots and hot moments on aggregate DN. Often in nitrogen balance approaches, DN is treated as the residual difference of the outputs and inputs derived from field measurements and farm management records. However, this provides little information about when and where DN occurs and assumes the remainder nitrogen is associated with this process. In this project we compare two methods of calculating DN as part of a farm nitrogen balance study. Method one uses an empirical relationship derived from in-situ DN measurements related to a soil topographic index. Method two characterizes the process with a model that tracks temperature, carbon availability, and soil moisture and is calibrated with in-situ DN measurements. When the nitrogen output by DN was calculated, both methods were successful in coming closer to closing the farm nitrogen balance. Results from method one identify annual hot spots of denitrification, while method two improves characterization of the daily hot moments of denitrification.

  9. Electron distribution functions and transport in laser-produced hot spots

    NASA Astrophysics Data System (ADS)

    Rozmus, Wojciech; Batishchev, Oleg; Brantov, A. V.; Bychenkov, V. Yu.; Capjack, C. E.; Sydora, R.

    2002-11-01

    The geometry of a laser hot spot is fundamental to the randomized laser beams and several single beam interaction experiments. Localized inverse Bremsstrahlung (IB) heating of the plasma and heat transport away from a hot spot produce nonequilibrium electron distribution functions (EDF) [1,2]. We have performed series of Fokker-Planck (FP) simulations and analytical studies to characterize EDF for a wide range of laser intensities and hot spot sizes. The FP code includes variations on the fast time scale of electromagnetic wave oscillations, self-consistent ambipolar electric field, nonlinear electron-electron and electron-ion collisions. Plasma inhomogeneity is described in one spatial dimension. Nonequilibrium EDF evolve due to competing effects of IB heating which flattens the bulk of the EDF, electron-electron collisions which drive the system towards equilibrium and nonlocal spatial transport which enhances high energy tails in the EDF. We have investigated anisotropy of EDF and threshold conditions for the excitation of return current ion wave instability. [1] S. Brunner and E. Valeo, Phys. Plasmas 9, 923 (2002). [2] O. V. Batishchev, et al. Phys. Plasmas 9, 2302 (2002).

  10. Acoustic timescale characterisation of a one-dimensional model hot spot

    NASA Astrophysics Data System (ADS)

    Kurtz, Michael D.; Regele, Jonathan D.

    2014-09-01

    Hot spots have been shown to be the autoignition centre in reactive mixtures. Linear temperature gradients and thermal stratification are used to characterise their behaviour. In this work, a model hot spot is considered by combining a linear temperature gradient with a constant temperature plateau. This approach retains the simplicity of a linear temperature gradient, but captures the effects of a local temperature maximum of finite size. A one-step Arrhenius reaction for H2-air is used to model the reactive mixture. Plateaus of three different initial sizes spanning two orders of magnitude are simulated. Each length corresponds to a different ratio of excitation time to acoustic time. It is shown that ratios less than unity react at nearly isochoric conditions while ratios greater than unity react at nearly isobaric conditions. Furthermore, it is demonstrated that the gasdynamic response is characterised by the a priori prescribed hot spot acoustic timescale ratio. Based upon the prescribed timescale ratio, it is shown that the plateau can have either a substantial or negligible impact on the reaction of a surrounding temperature gradient. This is explored further as the slope of the temperature gradient is varied. Based upon the heating-to-acoustic timescale ratio, plateaus of a particular size are shown to facilitate detonation formation inside gradients that would otherwise not detonate.

  11. The Canary and Cape Verde hot spots: morphological and geological links

    NASA Astrophysics Data System (ADS)

    Patriat, M.; Olivet, J. L.; Sahabi, M.; Aslanian, D.; Géli, L.

    2003-04-01

    The Canary and Cape-Verde achipelagoes are two groups of volcanic islands, 1400 km apart, located along the African margin of the Central Atlantic Ocean. They are often cited as case examples of the surface expression of two distinct hot-spot plumes. Their distribution, which does not define a line as much oceanic islands of the Pacific Ocean do, but a cluster, is considered as an indication of the steadiness of the African plate in the hot spots reference frame. From a bibliographic review and an examination of existing seismic profiles we emphasize the similarities existing between these two archipelagoes. - A continuous morphological basement ridge does exist along the margin that links the two archipelagoes. - An almost synchronous geological evolution is deduced from the stratigraphy of Fuerteventura island (Canary), Maio island (Cape-Verde), and the few DSDP holes in the area. The stratigraphic record evidences a Late Cretaceous/early Tertiary uplift following the classical oceanic subsidence but pre-dating the Tertiary volcanism that made the islands, or at least their aerial part. These geological arguments induces us to contest the relevance to put two distinct hot spot plumes forward to explain the evolution of such closely related geological structures.

  12. Weak shock loadings induce potential hot spots formation around an intergranular pore

    NASA Astrophysics Data System (ADS)

    Ma, Xiao; Li, Xinguo; Zheng, Xianxu; Guo, Wencan; Li, Jianling

    2017-03-01

    The weak shock loading plays the leading role in the unexpected explosion accidents of condensed-phase explosives. Under the weak shock loading conditions, the shear localization is the main factor affecting the formation of hot spots. When a planar stress wave crosses over a pore in the polymeric binder of the polymer bonded explosive (called intergranular pore), the shear localization comes out around the pore, which may induce potential hot spots formation in the polymeric binder and cause the chemical reaction of the nearby energetic crystal granules. In the present work, a novel experiment system consisting of time-resolved shadowgraph and laser-driven compressions was used to record the interactions between the planar stress wave and the intergranular pore. Then, a two-dimensional numerical simulation was performed to calculate the shear localization and the temperature rise around the intergranular pore. The simulation results were in good agreement with the experiments. Finally, the locations of the potential hot spots were determined, and the variations of the locations with the impulse width of incident stress wave were discussed.

  13. Hot Spot Electron Temperature from X-Ray Continuum Measurements on the NIF

    NASA Astrophysics Data System (ADS)

    Jarrott, Leonard; Chen, Hui; Izumi, Nobuhiko; Khan, Shahab; Ma, Tammy; Nagel, Sabrina; Pak, Arthur; Patel, Pravesh; Schneider, Marilyn; Scott, Howard

    2015-11-01

    We report on direct measurements of the electron temperature within the hot spot of inertially confined, layered, spherical implosions on the National Ignition Facility using a new differential filtering diagnostic. Measurements of the DT and DD ion temperatures using neutron time-of-flight detectors are complicated by the contribution of hot spot motion to the peak width, which may produce an apparent temperature higher than the thermal temperature. The electron temperature is not sensitive to this non-thermal velocity and is thus a valuable input to interpreting the stagnated hot spot conditions. Here we discuss a new electron temperature measurement using the high energy (>15 keV) emitted continuum from the hotspot that can escape with minimal attenuation from the compressed fuel/shell. We will discuss the physics considerations for design of this new large-pinhole, hard x-ray imaging technique, and show preliminary data acquired from symcaps and DT-layered implosions. Validation of this technique against simulations and other diagnostics is performed to estimate the accuracy of the measurement. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  14. DNA methylation epigenetically silences crossover hot spots and controls chromosomal domains of meiotic recombination in Arabidopsis.

    PubMed

    Yelina, Nataliya E; Lambing, Christophe; Hardcastle, Thomas J; Zhao, Xiaohui; Santos, Bruno; Henderson, Ian R

    2015-10-15

    During meiosis, homologous chromosomes undergo crossover recombination, which is typically concentrated in narrow hot spots that are controlled by genetic and epigenetic information. Arabidopsis chromosomes are highly DNA methylated in the repetitive centromeres, which are also crossover-suppressed. Here we demonstrate that RNA-directed DNA methylation is sufficient to locally silence Arabidopsis euchromatic crossover hot spots and is associated with increased nucleosome density and H3K9me2. However, loss of CG DNA methylation maintenance in met1 triggers epigenetic crossover remodeling at the chromosome scale, with pericentromeric decreases and euchromatic increases in recombination. We used recombination mutants that alter interfering and noninterfering crossover repair pathways (fancm and zip4) to demonstrate that remodeling primarily involves redistribution of interfering crossovers. Using whole-genome bisulfite sequencing, we show that crossover remodeling is driven by loss of CG methylation within the centromeric regions. Using cytogenetics, we profiled meiotic DNA double-strand break (DSB) foci in met1 and found them unchanged relative to wild type. We propose that met1 chromosome structure is altered, causing centromere-proximal DSBs to be inhibited from maturation into interfering crossovers. These data demonstrate that DNA methylation is sufficient to silence crossover hot spots and plays a key role in establishing domains of meiotic recombination along chromosomes.

  15. Hot-spot heating susceptibility due to reverse bias operating conditions

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.

    1985-01-01

    Because of field experience (indicating that cell and module degradation could occur as a result of hot spot heating), a laboratory test was developed at JPL to determine hot spot susceptibility of modules. The initial hot spot testing work at JPL formed a foundation for the test development. Test parameters are selected as follows. For high shunt resistance cells, the applied back bias test current is set equal to the test cell current at maximum power. For low shunt resistance cells, the test current is set equal to the cell short circuit current. The shadow level is selected to conform to that which would lead to maximum back bias voltage under the appropriate test current level. The test voltage is determined by the bypass diode frequency. The test conditions are meant to simulate the thermal boundary conditions for 100 mW/sq cm, 40C ambient environment. The test lasts 100 hours. A key assumption made during the development of the test is that no current imbalance results from the connecting of multiparallel cell strings. Therefore, the test as originally developed was applicable for single string case only.

  16. In Situ Hot-Spot Assembly as a General Strategy for Probing Single Biomolecules.

    PubMed

    Liu, Huiqiao; Li, Qiang; Li, Mingmin; Ma, Sisi; Liu, Dingbin

    2017-05-02

    Single-molecule detection using surface-enhanced Raman spectroscopy (SERS) has attracted increasing attention in chemical and biomedical analysis. However, it remains a major challenge to probe single biomolecules by means of SERS hot spots owing to the small volume of hot spots and their random distribution on substrates. We here report an in situ hot-spot assembly method as a general strategy for probing single biomolecules. As a proof-of-concept, this proposed strategy was successfully used for the detection of single microRNA-21 (miRNA-21, a potential cancer biomarker) at the single-cell level, showing great capability in differentiating the expression of miRNA-21 in single cancer cells from normal cells. This approach was further extended to single-protein detection. The versatility of the strategy opens an exciting avenue for single-molecule detection of biomarkers of interest and thus holds great promise in a variety of biological and biomedical applications.

  17. Hot spot activity and tectonic settings near Amsterdam-St. Paul plateau (Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Janin, M.; HéMond, C.; Guillou, H.; Maia, M.; Johnson, K. T. M.; Bollinger, C.; Liorzou, C.; Mudholkar, A.

    2011-05-01

    The Amsterdam-St. Paul (ASP) plateau is located in the central part of the Indian Ocean and results from the interaction between the ASP hot spot and the Southeast Indian Ridge (SEIR). It is located near the diffuse boundary between the Capricorn and Australian plates. The seamount chain of the Dead Poets (CDP) is northeast of the ASP plateau and may represent older volcanism related to the ASP hot spot; this chain consists of two groups of seamounts: (1) large flat-topped seamounts formed 8-10 Ma and (2) smaller conical seamounts formed during the last 2 Myr. The ASP hot spot has produced two pulses of magmatism that have been ponded under the ASP plateau and erupted along the divergent boundary between the Capricorn and Australian plates. The N65° orientation of the CDP as well as the seamount's elongated shapes support an opening motion between the Capricorn and Australian plates along a suture oriented in the N155° direction. This motion compared to the Antarctic plate amounts to an apparent velocity of 7.7 cm/yr northeastward for the Capricorn-Australian block. This motion does not fit with a fixed plume model. We suggest, therefore, that the ASP plume experienced a motion of about 1-2 cm/yr to the SW, which is opposite to the asthenospheric flow in this region and suggests a deep-seated plume.

  18. Resolving hot spot microstructure using x-ray penumbral imaging (invited)

    SciTech Connect

    Bachmann, B. Field, J.; Masters, N.; Pardini, T.; Rygg, J. R.; Benedetti, L. R.; Döppner, T.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L.; Hilsabeck, T.; Reed, C.; Alexander, N.; Forsman, A.

    2016-11-15

    We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

  19. The FTMap family of web servers for determining and characterizing ligand binding hot spots of proteins

    PubMed Central

    Kozakov, Dima; Grove, Laurie E.; Hall, David R.; Bohnuud, Tanggis; Mottarella, Scott; Luo, Lingqi; Xia, Bing; Beglov, Dmitri; Vajda, Sandor

    2016-01-01

    FTMap is a computational mapping server that identifies binding hot spots of macromolecules, i.e., regions of the surface with major contributions to the ligand binding free energy. To use FTMap, users submit a protein, DNA, or RNA structure in PDB format. FTMap samples billions of positions of small organic molecules used as probes and scores the probe poses using a detailed energy expression. Regions that bind clusters of multiple probe types identify the binding hot spots, in good agreement with experimental data. FTMap serves as basis for other servers, namely FTSite to predict ligand binding sites, FTFlex to account for side chain flexibility, FTMap/param to parameterize additional probes, and FTDyn to map ensembles of protein structures. Applications include determining druggability of proteins, identifying ligand moieties that are most important for binding, finding the most bound-like conformation in ensembles of unliganded protein structures, and providing input for fragment based drug design. FTMap is more accurate than classical mapping methods such as GRID and MCSS, and is much faster than the more recent approaches to protein mapping based on mixed molecular dynamics. Using 16 probe molecules, the FTMap server finds the hot spots of an average size protein in less than an hour. Since FTFlex performs mapping for all low energy conformers of side chains in the binding site, its completion time is proportionately longer. PMID:25855957

  20. Hot spots created at skin-air interfaces during ultrasound hyperthermia.

    PubMed

    Hynynen, K

    1990-01-01

    It is well known that ultrasound beams will be completely reflected at a soft-tissue-gas interface. The reflected beam is contributing to the power absorption at the tissue interface and may cause a hot spot which could prevent therapeutic temperatures at the treatment volume. In this study the temperature elevation caused by a reflected ultrasound beam at the skin surface has been investigated in dogs' thighs in vivo. The magnitude of the hot spot was quantified and the effect of entrance angle was also investigated. In addition, the possibility of eliminating the hot spot by coupling the beam out of the tissue was studied. The results showed that the temperature elevation can be up to four times larger at the skin-air surface than in resting muscle under similar exposure. The geometry of the reflecting surface had a significant effect on the temperature distribution. When the sound was coupled out of the tissue the magnitude of the temperature elevation at the skin reduced to less than half (depending on the geometry) but was still larger than temperatures measured in muscle. These results suggest the need for computerized treatment planning for scanned focused ultrasound treatments.

  1. Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering

    NASA Astrophysics Data System (ADS)

    Koshelev, A. E.

    2016-09-01

    Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. We explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect ("hot spots" or "hot lines"). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behavior of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. We discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.

  2. The topographic wetness index as a predictor for hot spots of DOC export from catchments

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Oosterwoud, Marieke; Tittel, Jörg; Selle, Benny; Fleckenstein, Jan H.

    2015-04-01

    Dissolved organic carbon (DOC) concentrations in the discharge of many catchments in Europe and North America are rising. This increase is of concern for the drinking water supply from reservoirs since high DOC concentrations cause additional costs in water treatment and potentially the formation of harmful disinfection by-products. A prerequisite for understanding this increase is the knowledge on the spatial distribution of dominant soil DOC sources within catchments and on mobilization as well as transfer processes to the surface water. A number of studies identified wetland soils as the dominant source with fast mobilization and short transit times to the receiving surface water. However, most studies have either focussed on smaller, hillslope and single catchment or on larger scale multi-catchment assessments. Moreover, information on the distribution of soil types in catchments is not always readily available. This study brings together both types of assessment in a data-driven top-down approach: (i) a detailed survey on DOC concentration and loads over the course of one year within two paired data-rich catchments discharging into a large drinking water reservoir in central Germany and (ii) a database of hydrochemistry and physio-geographic characteristics of 113 catchments draining into 58 reservoirs across Germany over the course of 16 years. The objective is to define hot spots of DOC export within the catchments for both types of assessments (i, ii) and to test the suitability of the topographic wetness index (TWI) as a proxy for well-connected wetland soils at various spatial scales. In the sub-catchments of assessment (i) the spatial variability of concentrations and loads was much smaller than expected. None of the studied sub-catchments was a predominant producer of the total DOC loads exported from the catchments. We found the mean concentrations and loads to be positively correlated with the share of groundwater-dominated soils in the sub

  3. Wood ant nests as hot spots of carbon dioxide production and cold spots of methane oxidation in temperate forests

    NASA Astrophysics Data System (ADS)

    Jilkova, Veronika; Picek, Tomas; Cajthaml, Tomas; Frouz, Jan

    2016-04-01

    Wood ant nests are known as hot spots of carbon dioxide (CO2) production and are also thought to affect methane (CH4) flux. Stable high temperatures are maintained in ant nests even in cold environments. Here we focused on quantification of CO2 and CH4 flux in wood ant nests, contribution of ants and microbes to CO2 production, properties of nest material that affect CO2 production and the role of ants and microbes in the maintenance of nest temperature. The research was conducted in temperate and boreal forests inhabited by wood ants (Formica s. str.). Gas fluxes were measured either by an infrared gas analyser or a static chamber technique. Ants and nest materials were also incubated in a laboratory. Material properties potentially influencing CO2 flux, such as moisture, nutrient content or temperature were determined. According to the results, CH4 oxidation was lower in wood ant nests than in the surrounding forest soil suggesting that some characteristics of ant nests hinder CH4 oxidation or promote CH4 production. These characteristics were mainly available carbon and nitrogen contents. Wood ant nests clearly are hot spots of CO2 production in temperate forests originating mainly from ant and also from microbial metabolism. Most important properties positively affecting CO2 production were found to be moisture, nutrient content and temperature. Nest temperature is maintained by ant and microbial metabolism; nests from colder environments produce more metabolic heat to maintain similar temperature as nests from warmer environments. In conclusion, as the abundance of wood ant nests in some forests can be very high, ant nests may largely increase heterogeneity in greenhouse gas fluxes in forest ecosystems.

  4. Visualization and detection of spatio-temporal hot-spot and cluster for dengue in Petaling district, Malaysia

    NASA Astrophysics Data System (ADS)

    Rizwan, M.; Dass, Sarat C.; Sagayan, Vijanth

    2016-11-01

    Hot-spot and cluster detection is a part of disease surveillance to find out which regions are effected most by the disease. Analysis of these clusters of disease used for longer periods of time can lead to future prediction of disease outbreaks. Dengue is one of the most important arboviral disease in Malaysia which needs proper surveillance and control strategies. Our current study presents hot-spot and cluster detection of dengue outbreaks in the district of Petaling, Selangor in Malaysia during the year 2014 using the registered cases of dengue in the district. Detected hot-spot from this spatio-temporal analysis of registered dengue could provide a trend for the future dengue outbreak predictions. Use of dengue registered cases for the future prediction could be more effective then using land use variables and climate data. R software is used for the hot-spots detection. Custom clustering definition is considered for the analysis.

  5. Preliminary results on the composition of Jupiter's troposphere in hot spot regions from the JIRAM/Juno instrument

    NASA Astrophysics Data System (ADS)

    Grassi, D.; Adriani, A.; Mura, A.; Dinelli, B. M.; Sindoni, G.; Turrini, D.; Filacchione, G.; Migliorini, A.; Moriconi, M. L.; Tosi, F.; Noschese, R.; Cicchetti, A.; Altieri, F.; Fabiano, F.; Piccioni, G.; Stefani, S.; Atreya, S.; Lunine, J.; Orton, G.; Ingersoll, A.; Bolton, S.; Levin, S.; Connerney, J.; Olivieri, A.; Amoroso, M.

    2017-05-01

    The Jupiter InfraRed Auroral Mapper (JIRAM) instrument on board the Juno spacecraft performed observations of two bright Jupiter hot spots around the time of the first Juno pericenter passage on 27 August 2016. The spectra acquired in the 4-5 µm spectral range were analyzed to infer the residual opacities of the uppermost cloud deck as well as the mean mixing ratios of water, ammonia, and phosphine at the approximate level of few bars. Our results support the current view of hot spots as regions of prevailing descending vertical motions in the atmosphere but extend this view suggesting that upwelling may occur at the southern boundaries of these structures. Comparison with the global ammonia abundance measured by Juno Microwave Radiometer suggests also that hot spots may represent sites of local enrichment of this gas. JIRAM also identifies similar spatial patterns in water and phosphine contents in the two hot spots.

  6. Characterization of hot spots for natural chloroform formation: Relevance for groundwater quality

    NASA Astrophysics Data System (ADS)

    Jacobsen, Ole S.; Albers, Christian N.; Laier, Troels

    2015-04-01

    Chloroform soil hot spot may deteriorate groundwater quality and may even result in chloroform concentration exceeding the Danish maximum limit of 1 µg/L in groundwater for potable use. In order to characterize the soil properties important for the chloroform production, various ecosystems were examined with respect to soil air chloroform and soil organic matter type and content. Coniferous forest areas, responsible for highest chloroform concentrations, were examined on widely different scales from km to cm scale. Furthermore, regular soil gas measurements including chloroform were performed during 4 seasons at various depths, together with various meteorological measurements and soil temperature recordings. Laboratory incubation experiments were also performed on undisturbed soil samples in order to examine the role of various microbiota, fungi and bacteria. To identify hot spots responsible for the natural contamination we have measured the production of chloroform in the upper soil from different terrestrial systems. Field measurements of chloroform in top soil air were used as production indicators. The production was however not evenly distributed at any scale. The ecosystems seem to have quite different net-productions of chloroform from very low in grassland to very high in some coniferous forests. Within the forest ecosystem we found large variation in chloroform concentrations depending on vegetation. In beech forest we found the lowest values, somewhat higher in an open pine forest, but the highest concentrations were detected in spruce forest without any vegetation beneath. Within this ecotype, it appeared that the variation was also large; hot spots with 2-4 decades higher production than the surrounding area. These hot spots were not in any way visually different from the surroundings and were of variable size from 3 to 20 meters in diameter. Besides this, measurements within a seemingly homogenous hot spot showed that there was still high

  7. Hot spots

    NASA Astrophysics Data System (ADS)

    Government officials in Montserrat and in Nicaragua spent the first week of December trying to usher residents out of their homes and away from simmering volcanoes in each of those nations. Some people cooperated, others decided to take their chances. On the tiny Caribbean island of Montserrat, about 3,500 people were ordered to vacate their homes for the second time in three months, as a lava dome in the Chances Peak volcano grew and threatened to erupt. In Leon, Nicaragua, at least a third of the 12,000 people ordered to evacuate their homes refused, choosing to protect their homes from looters rather than flee the gurgling Cerro Negro. The Nicaraguan volcano spewed ash and lava 900 m into the air on Dec. 2; the eruption was visible from Managua, 120 km to the southeast.

  8. Fossil hot spot-ridge interaction in the Musicians Seamount Province: Geophysical investigations of hot spot volcanism at volcanic elongated ridges

    NASA Astrophysics Data System (ADS)

    Kopp, H.; Kopp, C.; Phipps Morgan, J.; Flueh, E. R.; Weinrebe, W.; Morgan, W. J.

    2003-03-01

    The Musicians Seamount Province is a group of volcanic elongated ridges (VERs) and single seamounts located north of the Hawaiian Chain. A 327° trending seamount chain defines the western part of the province and has been interpreted as the expression of a Cretaceous hot spot beneath the northward moving Pacific Plate. To the east, elongated E-W striking ridges dominate the morphology. In 1999, wide-angle seismic data were collected across two 400 km long VERs. We present tomographic images of the volcanic edifices, which indicate that crustal thickening occurs in oceanic layer 2 rather than in layer 3. This extrusive style of volcanism appears to strongly contrast with the formation processes of aseismic ridges, where crustal thickening is mostly accommodated by intrusive underplating. High-resolution bathymetry was also collected, which yields a detailed image of the morphology of the VERs. From the occurrence of flat-top guyots and from the unique geomorphologic setting, two independent age constraints for the Pacific crust during the Cretaceous "quiet" zone are obtained, allowing a tectonic reconstruction for the formation of the Musicians VERs. Hot spot-ridge interaction leads to asthenosphere channeling from the plume to the nearby spreading center over a maximum distance of 400 km. The Musicians VERs were formed by mainly extrusive volcanism on top of this melt-generating channel. The proposed formation model may be applicable to a number of observed volcanic ridges in the Pacific, including the Tuamotu Isles, the eastern portion of the Foundation chain, and the western termination of the Salas y Gomez seamount chain.

  9. Role of microstructure and thermal transport in determining the rate of hot spot growth in aluminized PBX

    NASA Astrophysics Data System (ADS)

    Joshi, Kaushik; Chaudhuri, Santanu

    The mechanisms of initiation and propagation of a hot spot in non-ideal explosives with aluminum additives are poorly understood due to greater complexity introduced by the different thermal and mechanical behavior of the components. In aluminized composites such as PBXN-109, the binder, RDX and Aluminum phases have been studied separately. However, not much is known about deflection of hot spots in the microstructured composite. Especially, the role of adhesion, debonding and thermal conductivity of binder phase is critical in moderating the sensitivity of such interfaces. Using reactive molecular dynamics simulations, the primary binder interfaces in PBXN-109 was investigated. Depending on the temperature of the growing hot spot reaching an RDX or Al/Al2O3 grain, the thermal conductivity and viscoplastic behavior of the binder interface determine the attenuation of reaction front and thermal shock leading the hot spot. Different mechanisms like melt-dispersion and failure of oxide layer for the release of Al in the hot spot regions remain underexplored to connect the chemistry to the microstructure. Although Al/Al2O3/RDX and Al/Al2O3/HTPB interfaces are chemically stable, the hot spot melts the AlxOy layers and create shear bands in aluminum domain due to thermomechanical strain created due to different thermal environment. In a shock-compressed microstructure without voids, the cohesive interaction and chemical composition of such interfaces for different phases of RDX will be presented.

  10. Large-volume hot spots in gold spiky nanoparticle dimers for high-performance surface-enhanced spectroscopy.

    PubMed

    Li, Anran; Li, Shuzhou

    2014-11-07

    Hot spots with a large electric field enhancement usually come in small volumes, limiting their applications in surface-enhanced spectroscopy. Using a finite-difference time-domain method, we demonstrate that spiky nanoparticle dimers (SNPD) can provide hot spots with both large electric field enhancement and large volumes because of the pronounced lightning rod effect of spiky nanoparticles. We find that the strongest electric fields lie in the gap region when SNPD is in a tip-to-tip (T-T) configuration. The enhancement of electric fields (|E|(2)/|E0|(2)) in T-T SNPD with a 2 nm gap can be as large as 1.21 × 10(6). And the hot spot volume in T-T SNPD is almost 7 times and 5 times larger than those in the spike dimer and sphere dimer with the same gap size of 2 nm, respectively. The hot spot volume in SNPD can be further improved by manipulating the arrangements of spiky nanoparticles, where crossed T-T SNPD provides the largest hot spot volume, which is 1.5 times that of T-T SNPD. Our results provide a strategy to obtain hot spots with both intense electric fields and large volume by adding a bulky core at one end of the spindly building block in dimers.

  11. Hot spot mitigation in microprocessors by application of single phase microchannel heat sink and microprocessor floor planning

    NASA Astrophysics Data System (ADS)

    Chauhan, Anjali

    Poor thermal management in high frequency microprocessors results in thermal and mechanical stresses in the chip due to leakage losses, occurrence of hot spots and large temperature gradients. A micro-fluidics based cooling scheme of single phase microchannel heat sinks is found to be most promising cooling solution. Microchannel heat sinks have high cooling capability because of its high surface area to volume ratio and high heat transfer coefficient. Besides the fluid flow, heat transfer mechanism in microchannel heat sinks is affected by its installation on the microprocessor chip. Since microchannel heat sinks are capable of reducing only the average temperature rise of the microprocessor chip, technique of microprocessor floor planning can be applied to reduce hot spot temperature, mitigate multiple hot spots and reduce large temperature gradients on the surface of microprocessor chip. In this study, adequate installation of the microchannel heat sink on the processor chip has been proposed to extract maximum heat from the device. Microprocessor floor planning has also been explored to obtain an optimum chip floor plan on grounds of low performance penalty, low hot spot temperature and minimum number hot spots. The dependence of maximum hot spot temperature of the chip on pressure gradient across the microchannels has also been discussed.

  12. Water, ammonia, and H 2S mixing ratios in Jupiter's five-micron hot spots: A dynamical model

    NASA Astrophysics Data System (ADS)

    Friedson, A. James

    2005-09-01

    The Galileo probe entered the jovian atmosphere at the southern edge of a 5-micron hot spot, one of typically 8-10 quasi-evenly-spaced longitudinal areas of anomalously high 5-micron IR emission that reside in a narrow latitude band centered on +7.5 degrees. These hot spots are characterized primarily by a low abundance of the cloud particles that dominate the 5-micron opacity at other locations on the planet, and by significant desiccation of ammonia, water and hydrogen sulfide in the upper layers of the troposphere. Ortiz et al. [1998. Evolution and persistence of 5-micron hot spots at the Galileo probe entry latitude. J. Geophys. Res. 103, 23,051-23,069] found that the latitude and drift rate of the hot spots could be explained if they are formed by an equatorially trapped Rossby wave of meridional degree 1 moving with a phase speed between 99 and 103 m s -1 relative to System III. Here we model additional properties of the hot spots in terms of the amplitude saturation of such a wave propagating in the weakly stratified deep troposphere. We identify the hot spots with locations where the wave plus mean thermal stratification becomes marginally stable. In these locations, potential temperature isotherms stretch downward to very deep levels in the troposphere. Since fluid parcels follow these isotherms under adiabatic flow conditions, the parcels dive downward when they enter the portion of the wave associated with the hot spot and soar upward upon leaving the spot. We show that this model can account for the anomalous vertical profiles of NH 3, H 2O, and H 2S mixing ratio measured by the Galileo probe. Pressures vary by as much as 20 bar over potential temperature isotherms in solutions that produce sufficient desiccation of water and H 2S in hot spots. Approximately 6×10 of Jupiter's internal heat flux must be tapped to maintain the wave over the mean hot spot lifetime of 10 7 s. The results suggest that the phenomenon that causes hot spots may occur widely

  13. Identification of environmental anomaly hot spots in West Africa from time series of NDVI and rainfall

    NASA Astrophysics Data System (ADS)

    Boschetti, Mirco; Nutini, Francesco; Brivio, Pietro Alessandro; Bartholomé, Etienne; Stroppiana, Daniela; Hoscilo, Agata

    2013-04-01

    Studies of the impact of human activity on vegetation dynamics of the Sahelian belt of Africa have been recently re-invigorated by new scientific findings that highlighted the primary role of climate in the drought crises of the 1970s-1980s. Time series of satellite observations revealed a re-greening of the Sahelian belt that indicates no noteworthy human effect on vegetation dynamics at sub continental scale from the 1980s to late 1990s. However, several regional/local crises related to natural resources occurred in the last decades despite the re-greening thus underlying that more detailed studies are needed. In this study we used time-series (1998-2010) of SPOT-VGT NDVI and FEWS-RFE rainfall estimates to analyse vegetation - rainfall correlation and to map areas of local environmental anomalies where significant vegetation variations (increase/decrease) are not fully explained by seasonal changes of rainfall. Some of these anomalous zones (hot spots) were further analysed with higher resolution images Landsat TM/ETM+ to evaluate the reliability of the identified anomalous behaviour and to provide an interpretation of some example hot spots. The frequency distribution of the hot spots among the land cover classes of the GlobCover map shows that increase in vegetation greenness is mainly located in the more humid southern part and close to inland water bodies where it is likely to be related to the expansion/intensification of irrigated agricultural activities. On the contrary, a decrease in vegetation greenness occurs mainly in the northern part (12°-15°N) in correspondence with herbaceous vegetation covers where pastoral and cropping practices are often critical due to low and very unpredictable rainfall. The results of this study show that even if a general positive re-greening due to increased rainfall is evident for the entire Sahel, some local anomalous hot spots exist and can be explained by human factors such as population growth whose level reaches the

  14. Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering

    DOE PAGES

    Koshelev, A. E.

    2016-09-30

    Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. In this paper, we explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect (“hot spots” or “hot lines”). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behaviormore » of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. Finally, we discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.« less

  15. Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering

    SciTech Connect

    Koshelev, A. E.

    2016-09-30

    Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. In this paper, we explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect (“hot spots” or “hot lines”). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behavior of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. Finally, we discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.

  16. Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer

    DOE PAGES

    Jewell, Talia N. M.; Karaoz, Ulas; Bill, Markus; ...

    2017-01-25

    Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed andmore » incubated under anaerobic conditions in serum bottles with an initial N2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO2 fixation, H2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly

  17. Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer

    PubMed Central

    Jewell, Talia N. M.; Karaoz, Ulas; Bill, Markus; Chakraborty, Romy; Brodie, Eoin L.; Williams, Kenneth H.; Beller, Harry R.

    2017-01-01

    Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed and incubated under anaerobic conditions in serum bottles with an initial N2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO2 fixation, H2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed

  18. Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer.

    PubMed

    Jewell, Talia N M; Karaoz, Ulas; Bill, Markus; Chakraborty, Romy; Brodie, Eoin L; Williams, Kenneth H; Beller, Harry R

    2017-01-01

    Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed and incubated under anaerobic conditions in serum bottles with an initial N2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO2 fixation, H2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed

  19. Friction Stir Spot Welding of DP780 and Hot-Stamp Boron Steels

    SciTech Connect

    Santella, Michael L.; Frederick, Alan; Hovanski, Yuri; Grant, Glenn J.

    2008-05-16

    Friction stir spot welds were made in two high-strength steels: DP780, and a hot-stamp-boron steel with tensile strength of 1500 MPa. The spot welds were made at either 800 or 1600 rpm using either of two polycrystalline boron nitride tools. One stir tool, BN77, had the relatively common pin-tool shape. The second tool, BN46, had a convex rather than a concave shoulder profile and a much wider and shorter pin. The tools were plunged to preprogrammed depths either at a continuous rate (1-step schedule) or in two segments consisting of a relatively high rate followed by a slower rate. In all cases, the welds were completed in 4s. The range of lap-shear values were compared to values required for resistance spot welds on the same steels. The minimum value of 10.3 kN was exceeded for friction stir spot welding of DP780 using a 2-step schedule and either the BN77- or the BN46-type stir tool. The respective minimum value of 12 kN was also exceeded for the HSB steel using the 2-step process and the BN46 stir tool.

  20. Friction Stir Spot Welding of DP780 and Hot-Stamp Boron Steels

    SciTech Connect

    Santella, Michael L; Frederick, David Alan; Hovanski, Yuri; Grant, Glenn J

    2008-01-01

    Friction stir spot welds were made in two high-strength steels: DP780, and a hot-stamp-boron steel with tensile strength of 1500 MPa. The spot welds were made at either 800 or 1600 rpm using either of two polycrystalline boron nitride tools. One stir tool, BN77, had the relatively common pin-tool shape. The second tool, BN46, had a convex rather than a concave shoulder profile and a much wider and shorter pin. The tools were plunged to preprogrammed depths either at a continuous rate (1-step schedule) or in two segments consisting of a relatively high rate followed by a slower rate. In all cases, the welds were completed in 4s. The range of lap-shear values were compared to values required for resistance spot welds on the same steels. The minimum value of 10.3 kN was exceeded for friction stir spot welding of DP780 using a 2-step schedule and either the BN77- or the BN46-type stir tool. The respective minimum value of 12 kN was also exceeded for the HSB steel using the 2-step process and the BN46 stir tool.

  1. A healthcare utilization analysis framework for hot spotting and contextual anomaly detection.

    PubMed

    Hu, Jianying; Wang, Fei; Sun, Jimeng; Sorrentino, Robert; Ebadollahi, Shahram

    2012-01-01

    Patient medical records today contain vast amount of information regarding patient conditions along with treatment and procedure records. Systematic healthcare resource utilization analysis leveraging such observational data can provide critical insights to guide resource planning and improve the quality of care delivery while reducing cost. Of particular interest to providers are hot spotting: the ability to identify in a timely manner heavy users of the systems and their patterns of utilization so that targeted intervention programs can be instituted, and anomaly detection: the ability to identify anomalous utilization cases where the patients incurred levels of utilization that are unexpected given their clinical characteristics which may require corrective actions. Past work on medical utilization pattern analysis has focused on disease specific studies. We present a framework for utilization analysis that can be easily applied to any patient population. The framework includes two main components: utilization profiling and hot spotting, where we use a vector space model to represent patient utilization profiles, and apply clustering techniques to identify utilization groups within a given population and isolate high utilizers of different types; and contextual anomaly detection for utilization, where models that map patient's clinical characteristics to the utilization level are built in order to quantify the deviation between the expected and actual utilization levels and identify anomalies. We demonstrate the effectiveness of the framework using claims data collected from a population of 7667 diabetes patients. Our analysis demonstrates the usefulness of the proposed approaches in identifying clinically meaningful instances for both hot spotting and anomaly detection. In future work we plan to incorporate additional sources of observational data including EMRs and disease registries, and develop analytics models to leverage temporal relationships among

  2. A Healthcare Utilization Analysis Framework for Hot Spotting and Contextual Anomaly Detection

    PubMed Central

    Hu, Jianying; Wang, Fei; Sun, Jimeng; Sorrentino, Robert; Ebadollahi, Shahram

    2012-01-01

    Patient medical records today contain vast amount of information regarding patient conditions along with treatment and procedure records. Systematic healthcare resource utilization analysis leveraging such observational data can provide critical insights to guide resource planning and improve the quality of care delivery while reducing cost. Of particular interest to providers are hot spotting: the ability to identify in a timely manner heavy users of the systems and their patterns of utilization so that targeted intervention programs can be instituted, and anomaly detection: the ability to identify anomalous utilization cases where the patients incurred levels of utilization that are unexpected given their clinical characteristics which may require corrective actions. Past work on medical utilization pattern analysis has focused on disease specific studies. We present a framework for utilization analysis that can be easily applied to any patient population. The framework includes two main components: utilization profiling and hot spotting, where we use a vector space model to represent patient utilization profiles, and apply clustering techniques to identify utilization groups within a given population and isolate high utilizers of different types; and contextual anomaly detection for utilization, where models that map patient’s clinical characteristics to the utilization level are built in order to quantify the deviation between the expected and actual utilization levels and identify anomalies. We demonstrate the effectiveness of the framework using claims data collected from a population of 7667 diabetes patients. Our analysis demonstrates the usefulness of the proposed approaches in identifying clinically meaningful instances for both hot spotting and anomaly detection. In future work we plan to incorporate additional sources of observational data including EMRs and disease registries, and develop analytics models to leverage temporal relationships among

  3. TERT promoter hot spot mutations are frequent in Indian cervical and oral squamous cell carcinomas.

    PubMed

    Vinothkumar, Vilvanathan; Arunkumar, Ganesan; Revathidevi, Sundaramoorthy; Arun, Kanagaraj; Manikandan, Mayakannan; Rao, Arunagiri Kuha Deva Magendhra; Rajkumar, Kottayasamy Seenivasagam; Ajay, Chandrasekar; Rajaraman, Ramamurthy; Ramani, Rajendren; Murugan, Avaniyapuram Kannan; Munirajan, Arasambattu Kannan

    2016-06-01

    Squamous cell carcinoma (SCC) of the uterine cervix and oral cavity are most common cancers in India. Telomerase reverse transcriptase (TERT) overexpression is one of the hallmarks for cancer, and activation through promoter mutation C228T and C250T has been reported in variety of tumors and often shown to be associated with aggressive tumors. In the present study, we analyzed these two hot spot mutations in 181 primary tumors of the uterine cervix and oral cavity by direct DNA sequencing and correlated with patient's clinicopathological characteristics. We found relatively high frequency of TERT hot spot mutations in both cervical [21.4 % (30/140)] and oral [31.7 % (13/41)] squamous cell carcinomas. In cervical cancer, TERT promoter mutations were more prevalent (25 %) in human papilloma virus (HPV)-negative cases compared to HPV-positive cases (20.6 %), and both TERT promoter mutation and HPV infection were more commonly observed in advanced stage tumors (77 %). Similarly, the poor and moderately differentiated tumors of the uterine cervix had both the TERT hot spot mutations and HPV (16 and 18) at higher frequency (95.7 %). Interestingly, we observed eight homozygous mutations (six 228TT and two 250TT) only in cervical tumors, and all of them were found to be positive for high-risk HPV. To the best of our knowledge, this is the first study from India reporting high prevalence of TERT promoter mutations in primary tumors of the uterine cervix and oral cavity. Our results suggest that TERT reactivation through promoter mutation either alone or in association with the HPV oncogenes (E6 and E7) could play an important role in the carcinogenesis of cervical and oral cancers.

  4. Multiple modes of chromatin configuration at natural meiotic recombination hot spots in fission yeast.

    PubMed

    Hirota, Kouji; Steiner, Walter W; Shibata, Takehiko; Ohta, Kunihiro

    2007-11-01

    The ade6-M26 meiotic recombination hot spot of fission yeast is defined by a cyclic AMP-responsive element (CRE)-like heptanucleotide sequence, 5'-ATGACGT-3', which acts as a binding site for the Atf1/Pcr1 heterodimeric transcription factor required for hot spot activation. We previously demonstrated that the local chromatin around the M26 sequence motif alters to exhibit higher sensitivity to micrococcal nuclease before the initiation of meiotic recombination. In this study, we have examined whether or not such alterations in chromatin occur at natural meiotic DNA double-strand break (DSB) sites in Schizosaccharomyces pombe. At one of the most prominent DSB sites, mbs1 (meiotic break site 1), the chromatin structure has a constitutively accessible configuration at or near the DSB sites. The establishment of the open chromatin state and DSB formation are independent of the CRE-binding transcription factor, Atf1. Analysis of the chromatin configuration at CRE-dependent DSB sites revealed both differences from and similarities to mbs1. For example, the tdh1+ locus, which harbors a CRE consensus sequence near the DSB site, shows a meiotically induced open chromatin configuration, similar to ade6-M26. In contrast, the cds1+ locus is similar to mbs1 in that it exhibits a constitutive open configuration. Importantly, Atf1 is required for the open chromatin formation in both tdh1+ and cds1+. These results suggest that CRE-dependent meiotic chromatin changes are intrinsic processes related to DSB formation in fission yeast meiosis. In addition, the results suggest that the chromatin configuration in natural meiotic recombination hot spots can be classified into at least three distinct categories: (i) an Atf1-CRE-independent constitutively open chromatin configuration, (ii) an Atf1-CRE-dependent meiotically induced open chromatin configuration, and (iii) an Atf1-CRE-dependent constitutively open chromatin configuration.

  5. Using spatial statistics to identify emerging hot spots of forest loss

    NASA Astrophysics Data System (ADS)

    Harris, Nancy L.; Goldman, Elizabeth; Gabris, Christopher; Nordling, Jon; Minnemeyer, Susan; Ansari, Stephen; Lippmann, Michael; Bennett, Lauren; Raad, Mansour; Hansen, Matthew; Potapov, Peter

    2017-02-01

    As sources of data for global forest monitoring grow larger, more complex and numerous, data analysis and interpretation become critical bottlenecks for effectively using them to inform land use policy discussions. Here in this paper, we present a method that combines big data analytical tools with Emerging Hot Spot Analysis (ArcGIS) to identify statistically significant spatiotemporal trends of forest loss in Brazil, Indonesia and the Democratic Republic of Congo (DRC) between 2000 and 2014. Results indicate that while the overall rate of forest loss in Brazil declined over the 14-year time period, spatiotemporal patterns of loss shifted, with forest loss significantly diminishing within the Amazonian states of Mato Grosso and Rondônia and intensifying within the cerrado biome. In Indonesia, forest loss intensified in Riau province in Sumatra and in Sukamara and West Kotawaringin regencies in Central Kalimantan. Substantial portions of West Kalimantan became new and statistically significant hot spots of forest loss in the years 2013 and 2014. Similarly, vast areas of DRC emerged as significant new hot spots of forest loss, with intensified loss radiating out from city centers such as Beni and Kisangani. While our results focus on identifying significant trends at the national scale, we also demonstrate the scalability of our approach to smaller or larger regions depending on the area of interest and specific research question involved. When combined with other contextual information, these statistical data models can help isolate the most significant clusters of loss occurring over dynamic forest landscapes and provide more coherent guidance for the allocation of resources for forest monitoring and enforcement efforts.

  6. Multi-point fibre optic hot-spot network integrated into a high power transformer

    NASA Astrophysics Data System (ADS)

    Lobo Ribeiro, A. B.; Eira, N.; Sousa, J. M.; Guerreiro, P. T.; Salcedo, J. A. R.

    2007-07-01

    A multi-point fibre optic temperature sensor network integrated inside a power transformer for continuous monitoring of hot-spots on windings, cellulose insulations and oil, is demonstrated and tested. The temperature sensors are based on proprietary encapsulated fibre Bragg grating (FBG) sensors and the optical interrogation unit uses a special designed narrowband high power broadband fibre source. The fibre optic sensing network is integrated into a 440 MVA power transformer having 12 temperature sensing points, distributed over several physical locations inside de transformer (windings, cellulose insulators, magnetic circuit and cooling oil entrance and exit).

  7. Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules

    SciTech Connect

    Sanz, J.; Garnier, J.; Cherfils, C.; Canaud, B.; Masse, L.; Temporal, M.

    2005-11-15

    In the context of the French Laser-Megajoule fusion-research program, the hydrodynamic stability of the baseline direct-drive target is investigated at the hot spot surface during the deceleration phase by means of modeling and simulations. Using the convergence of the flow towards a self-similar solution, a closed system of ordinary differential equations is derived for the main hydrodynamic variables. An exact linear stability analysis is performed to compute the Rayleigh-Taylor growths. All theoretical predictions are compared to one-dimensional and two-dimensional single-mode detailed numerical results.

  8. Developing the Quantitative Histopathology Image Ontology (QHIO): A case study using the hot spot detection problem.

    PubMed

    Gurcan, Metin N; Tomaszewski, John; Overton, James A; Doyle, Scott; Ruttenberg, Alan; Smith, Barry

    2017-02-01

    Interoperability across data sets is a key challenge for quantitative histopathological imaging. There is a need for an ontology that can support effective merging of pathological image data with associated clinical and demographic data. To foster organized, cross-disciplinary, information-driven collaborations in the pathological imaging field, we propose to develop an ontology to represent imaging data and methods used in pathological imaging and analysis, and call it Quantitative Histopathological Imaging Ontology - QHIO. We apply QHIO to breast cancer hot-spot detection with the goal of enhancing reliability of detection by promoting the sharing of data between image analysts.

  9. Hot spot abundance, ridge subduction and the evolution of greenstone belts

    NASA Technical Reports Server (NTRS)

    Abbott, D.; Hoffman, S.

    1986-01-01

    A number of plate tectonic hypotheses have been proposed to explain the origin of Archaean and Phanerozoic greenstone/ophiolite terranes. In these models, ophiolites or greenstone belts represent the remnants of one or more of the following: island arcs, rifted continental margins, oceanic crustal sections, and hot spot volcanic products. If plate tectonics has been active since the creation of the Earth, it is logical to suppose that the same types of tectonic processes which form present day ophiolites also formed Archaean greenstone belts. However, the relative importance of the various tectonic processes may well have been different and are discussed.

  10. Detection of spatial hot spots and variation for the neon flying squid Ommastrephes bartramii resources in the northwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Feng, Yongjiu; Chen, Xinjun; Liu, Yan

    2016-08-01

    With the increasing effects of global climate change and fishing activities, the spatial distribution of the neon flying squid (Ommastrephes bartramii) is changing in the traditional fishing ground of 150°-160°E and 38°-45°N in the northwest Pacific Ocean. This research aims to identify the spatial hot and cold spots (i.e. spatial clusters) of O. bartramii to reveal its spatial structure using commercial fishery data from 2007 to 2010 collected by Chinese mainland squid-jigging fleets. A relatively strongly-clustered distribution for O. bartramii was observed using an exploratory spatial data analysis (ESDA) method. The results show two hot spots and one cold spot in 2007 while only one hot and one cold spots were identified each year from 2008 to 2010. The hot and cold spots in 2007 occupied 8.2% and 5.6% of the study area, respectively; these percentages for hot and cold spot areas were 5.8% and 3.1% in 2008, 10.2% and 2.9% in 2009, and 16.4% and 11.9% in 2010, respectively. Nearly half (>45%) of the squid from 2007 to 2009 reported by Chinese fleets were caught in hot spot areas while this percentage reached its peak at 68.8% in 2010, indicating that the hot spot areas are central fishing grounds. A further change analysis shows the area centered at 156°E/43.5°N was persistent as a hot spot over the whole period from 2007 to 2010. Furthermore, the hot spots were mainly identified in areas with sea surface temperature (SST) in the range of 15-20°C around warm Kuroshio Currents as well as with the chlorophyll-a (chl-a) concentration above 0.3 mg/m3. The outcome of this research improves our understanding of spatiotemporal hotspots and its variation for O. bartramii and is useful for sustainable exploitation, assessment, and management of this squid.

  11. Detection of spatial hot spots and variation for the neon flying squid Ommastrephes bartramii resources in the northwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Feng, Yongjiu; Chen, Xinjun; Liu, Yan

    2017-07-01

    With the increasing effects of global climate change and fishing activities, the spatial distribution of the neon flying squid ( Ommastrephes bartramii) is changing in the traditional fishing ground of 150°-160°E and 38°-45°N in the northwest Pacific Ocean. This research aims to identify the spatial hot and cold spots (i.e. spatial clusters) of O. bartramii to reveal its spatial structure using commercial fishery data from 2007 to 2010 collected by Chinese mainland squid-jigging fleets. A relatively strongly-clustered distribution for O. bartramii was observed using an exploratory spatial data analysis (ESDA) method. The results show two hot spots and one cold spot in 2007 while only one hot and one cold spots were identified each year from 2008 to 2010. The hot and cold spots in 2007 occupied 8.2% and 5.6% of the study area, respectively; these percentages for hot and cold spot areas were 5.8% and 3.1% in 2008, 10.2% and 2.9% in 2009, and 16.4% and 11.9% in 2010, respectively. Nearly half (>45%) of the squid from 2007 to 2009 reported by Chinese fleets were caught in hot spot areas while this percentage reached its peak at 68.8% in 2010, indicating that the hot spot areas are central fishing grounds. A further change analysis shows the area centered at 156°E/43.5°N was persistent as a hot spot over the whole period from 2007 to 2010. Furthermore, the hot spots were mainly identified in areas with sea surface temperature (SST) in the range of 15-20°C around warm Kuroshio Currents as well as with the chlorophyll- a (chl- a) concentration above 0.3 mg/m3. The outcome of this research improves our understanding of spatiotemporal hotspots and its variation for O. bartramii and is useful for sustainable exploitation, assessment, and management of this squid.

  12. A novel X-ray spectrometer for plasma hot spot diagnosis

    NASA Astrophysics Data System (ADS)

    Shi, Jun; Guo, Yongchao; Xiao, Shali; Yang, Zuhua; Qian, Feng; Cao, LeiFeng; Gu, Yuqiu

    2017-09-01

    A novel X-ray spectrometer is designed to diagnose the different conditions in plasmas. It can provide both X-ray spectroscopy and plasma image information simultaneously. Two pairs of elliptical crystal analyzers are used to measure the X-ray spectroscopy in the range of 2-20 keV. The pinhole imaging system coupled with gated micro-channel plate(MCP) detectors are developed, which allows 20 images to be collected in a single individual experiment. The experiments of measuring spectra were conducted at ;Shenguang-II upgraded laser; in China Academy of Engineering Physics to demonstrate the utility of the spectrometer. The X-ray spectroscopy information was obtained by the image plate(IP). The hot spot imaging experiments were carried out at ;Shenguang-III prototype facility;. We have obtained the hot sport images with the spectrometer, and the signal to noise ratio of 30 ∼ 40 is observed.

  13. Sensitivity of inertial confinement fusion hot spot properties to the deuterium-tritium fuel adiabat

    NASA Astrophysics Data System (ADS)

    Melvin, J.; Lim, H.; Rana, V.; Cheng, B.; Glimm, J.; Sharp, D. H.; Wilson, D. C.

    2015-02-01

    We determine the dependence of key Inertial Confinement Fusion (ICF) hot spot simulation properties on the deuterium-tritium fuel adiabat, here modified by addition of energy to the cold shell. Variation of this parameter reduces the simulation to experiment discrepancy in some, but not all, experimentally inferred quantities. Using simulations with radiation drives tuned to match experimental shots N120321 and N120405 from the National Ignition Campaign (NIC), we carry out sets of simulations with varying amounts of added entropy and examine the sensitivities of important experimental quantities. Neutron yields, burn widths, hot spot densities, and pressures follow a trend approaching their experimentally inferred quantities. Ion temperatures and areal densities are sensitive to the adiabat changes, but do not necessarily converge to their experimental quantities with the added entropy. This suggests that a modification to the simulation adiabat is one of, but not the only explanation of the observed simulation to experiment discrepancies. In addition, we use a theoretical model to predict 3D mix and observe a slight trend toward less mixing as the entropy is enhanced. Instantaneous quantities are assessed at the time of maximum neutron production, determined dynamically within each simulation. These trends contribute to ICF science, as an effort to understand the NIC simulation to experiment discrepancy, and in their relation to the high foot experiments, which features a higher adiabat in the experimental design and an improved neutron yield in the experimental results.

  14. A physically-based Mie–Gruneisen equation of state to determine hot spot temperature distributions

    DOE PAGES

    Kittell, David Erik; Yarrington, Cole Davis

    2016-07-14

    Here, a physically-based form of the Mie–Grüneisen equation of state (EOS) is derived for calculating 1d planar shock temperatures, as well as hot spot temperature distributions from heterogeneous impact simulations. This form utilises a multi-term Einstein oscillator model for specific heat, and is completely algebraic in terms of temperature, volume, an integrating factor, and the cold curve energy. Moreover, any empirical relation for the reference pressure and energy may be substituted into the equations via the use of a generalised reference function. The complete EOS is then applied to calculations of the Hugoniot temperature and simulation of hydrodynamic pore collapsemore » using data for the secondary explosive, hexanitrostilbene (HNS). From these results, it is shown that the choice of EOS is even more significant for determining hot spot temperature distributions than planar shock states. The complete EOS is also compared to an alternative derivation assuming that specific heat is a function of temperature alone, i.e. cv(T). Temperature discrepancies on the order of 100–600 K were observed corresponding to the shock pressures required to initiate HNS (near 10 GPa). Overall, the results of this work will improve confidence in temperature predictions. By adopting this EOS, future work may be able to assign physical meaning to other thermally sensitive constitutive model parameters necessary to predict the shock initiation and detonation of heterogeneous explosives.« less

  15. Computational Study of 3-D Hot-Spot Initiation in Shocked Insensitive High-Explosive

    NASA Astrophysics Data System (ADS)

    Najjar, F. M.; Howard, W. M.; Fried, L. E.

    2011-06-01

    High explosive shock sensitivity is controlled by a combination of mechanical response, thermal properties, and chemical properties. The interplay of these physical phenomena in realistic condensed energetic materials is currently lacking. A multiscale computational framework is developed investigating hot spot (void) ignition in a single crystal of an insensitive HE, TATB. Atomistic MD simulations are performed to provide the key chemical reactions and these reaction rates are used in 3-D multiphysics simulations. The multiphysics code, ALE3D, is linked to the chemistry software, Cheetah, and a three-way coupled approach is pursued including hydrodynamics, thermal and chemical analyses. A single spherical air bubble is embedded in the insensitive HE and its collapse due to shock initiation is evolved numerically in time; while the ignition processes due chemical reactions are studied. Our current predictions showcase several interesting features regarding hot spot dynamics including the formation of a ``secondary'' jet. Results obtained with hydro-thermo-chemical processes leading to ignition growth will be discussed for various pore sizes and different shock pressures. LLNL-ABS-471438. This work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  16. Identification of Hot Spots in Protein Structures Using Gaussian Network Model and Gaussian Naive Bayes

    PubMed Central

    Jiang, Tao; Shan, Guogen

    2016-01-01

    Residue fluctuations in protein structures have been shown to be highly associated with various protein functions. Gaussian network model (GNM), a simple representative coarse-grained model, was widely adopted to reveal function-related protein dynamics. We directly utilized the high frequency modes generated by GNM and further performed Gaussian Naive Bayes (GNB) to identify hot spot residues. Two coding schemes about the feature vectors were implemented with varying distance cutoffs for GNM and sliding window sizes for GNB based on tenfold cross validations: one by using only a single high mode and the other by combining multiple modes with the highest frequency. Our proposed methods outperformed the previous work that did not directly utilize the high frequency modes generated by GNM, with regard to overall performance evaluated using F1 measure. Moreover, we found that inclusion of more high frequency modes for a GNB classifier can significantly improve the sensitivity. The present study provided additional valuable insights into the relation between the hot spots and the residue fluctuations. PMID:27882325

  17. Hot spots and future directions of research on the neuroprotective effects of nimodipine

    PubMed Central

    Li, Runhui

    2014-01-01

    Calcium antagonists are widely used in the clinical treatment of ischemic cerebrovascular disease because of their vascular and neuroprotective effects. Nimodipine, a typical calcium antagonist, can cross the blood-brain barrier and act selectively at neurons and blood vessels of target tissues, thus exerting neuroprotective effects. The aim of the present study was to explore the hot spots and future trends of research on the neuroprotective effects of nimodipine. We retrieved 425 articles on the neuroprotective effects of nimodipine that were indexed in the Web of the Science database between 2000 and 2014. The retrieved articles were analyzed using document analysis reporting and the derived information function in the Web of Science, and the information visualization software CiteSpace III. The reference co-citation network was plotted, and the high frequency key words in these publications were used to analyze the research fronts and development trends for nimodipine neuroprotection. According to these co-citation clusters, the research front of nimodipine neuroprotection is the use of randomized controlled trials to study nimodipine intervention of subarachnoid hemorrhage. Using time zone view analysis on hot spots labeled with a key word, the areas of interest in the field of nimodipine neuroprotection are nimodipine pharmacology and therapeutics, blood-brain barrier, trials, and anti-angiospasm. PMID:25558246

  18. "Atomic Force Masking" Induced Formation of Effective Hot Spots along Grain Boundaries of Metal Thin Films.

    PubMed

    Kim, Kwang Hyun; Chae, Soo Sang; Jang, Seunghun; Choi, Won Jin; Chang, Hyunju; Lee, Jeong-O; Lee, Tae Il

    2016-11-30

    We present an interesting phenomenon, "atomic force masking", which is the deposition of a few-nanometer-thick gold film on ultrathin low-molecular-weight (LMW) polydimethylsiloxane (PDMS) engineered on a polycrystalline gold thin film, and demonstrated the formation of hot spot based on SERS. The essential principle of this atomic force masking phenomenon is that an LMW PDMS layer on a single crystalline grain of gold thin film would repel gold atoms approaching this region during a second cycle of evaporation, whereas new nucleation and growth of gold atoms would occur on LMW PDMS deposited on grain boundary regions. The nanostructure formed by the atomic force masking, denoted here as "hot spots on grain boundaries" (HOGs), which is consistent with finite-difference time-domain (FDTD) simulation, and the mechanism of atomic force masking were investigated by carrying out systematic experiments, and density functional theory (DFT) calculations were made to carefully explain the related fundamental physics. Also, to highlight the manufacturing advantages of the proposed method, we demonstrated the simple synthesis of a flexible HOG SERS, and we used this substrate in a swabbing test to detect a common pesticide placed on the surface of an apple.

  19. Cross-correlation search for a hot spot of gravitational waves

    SciTech Connect

    Dhurandhar, Sanjeev; Tagoshi, Hideyuki; Okada, Yuta; Kanda, Nobuyuki; Takahashi, Hirotaka

    2011-10-15

    The cross-correlation search has been previously applied to map the gravitational wave (GW) stochastic background in the sky and also to target GW from rotating neutron stars/pulsars. Here we investigate how the cross-correlation method can be used to target a small region in the sky spanning at most a few pixels, where a pixel in the sky is determined by the diffraction limit which depends on the (i) baseline joining a pair of detectors and (ii) detector bandwidth. Here as one of the promising targets, we consider the Virgo cluster--a ''hot spot'' spanning few pixels--which could contain, as estimates suggest {approx}10{sup 11} neutron stars, of which a small fraction would continuously emit GW in the bandwidth of the detectors. For the detector baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET, etc. Our results show that sufficient signal to noise can be accumulated with integration times of the order of a year if the ellipticity of neutron stars is larger than 10{sup -6}. The results improve for the multibaseline search. This analysis could as well be applied to other likely hot spots in the sky and other possible pairs of detectors.

  20. A review of algorithms for detecting volcanic hot spots in satellite infrared data

    NASA Astrophysics Data System (ADS)

    Steffke, Andrea M.; Harris, Andrew J. L.

    2011-11-01

    Since the 1980s, application of thermal infrared satellite data for volcano monitoring has rapidly evolved to become a proven operational tool. Due to the large quantities of data provided by sensors in polar and geostationary orbits, as well as the sheer number of active volcanoes on earth, processing and managing such data sets requires an enormous amount of workforce. A number of algorithms have been developed to facilitate detection, location, and tracking of hot spots of active volcanoes. A collation and review of hot spot detection algorithms developed and applied by the volcanological community reveals three main types which have been applied to date: contextual, fixed threshold, and temporal. The founding algorithms for these three classes are VAST, MODVOLC, and RST, respectively. Through comparison with manually based detections, the performance of each algorithm was tested for sustained lava flows (Etna and Stromboli), strombolian activity (Stromboli), lava dome growth and collapse (Augustine), and fumarole fields (Vulcano). It is shown that, as the number of correctly identified anomalies increases, so too does the number of false positives. Although each of the algorithms operates well within the limits and criteria of their design requirements and application, under current data restraints, no algorithm can be expected to perform perfectly.

  1. Passenger transgenes reveal intrinsic specificity of the antibody hypermutation mechanism: clustering, polarity, and specific hot spots.

    PubMed Central

    Betz, A G; Rada, C; Pannell, R; Milstein, C; Neuberger, M S

    1993-01-01

    We have analyzed somatic hypermutation in mice carrying an immunoglobulin kappa transgene in order to discriminate mutations that reflect the intrinsic specificity of the hypermutation mechanism from those highlighted by antigenic selection. We have immunized animals with three different immunogens. With one immunogen, the antigen-specific B cells express a transgenic kappa chain, which does not form part of the antibody; the transgene is a passenger free to accumulate unselected mutations. With the other two immunogens, the transgenic kappa chain constitutes the light chain of the expressed antibody. A comparison of the transgene mutations obtained under these different circumstances allows us to identify common features that we attribute to the intrinsic specificity of the hypermutation process. In particular, it yields only base substitutions and leads to hot spots occurring in individual positions (e.g., the second base of the Ser-31 codon). The mutations preferentially accumulate around the first complementarity-determining region. The process exhibits specific base substitution preferences with transitions being favored over transversions. We propose that these substitution preferences can be used to discriminate intrinsic from antigen-selected hot spots. We also note that hypermutation distinguishes between the coding and noncoding strands since pyrimidines (particularly thymidines) mutate less frequently than purines. PMID:8460148

  2. TRIPAS: A triapplicator system with relocatable 'hot spot' at tissue depth

    SciTech Connect

    Bicher, H.I.; Afuwape, S.A.; Wolfstein, R.S.; Bruley, D.F.; Reesman, K. )

    1990-01-01

    Solving the problem of heat focusing and standardization of the clinical application of hyperthermia requires a mathematical prediction model. The model should include the medium constitutive parameter, and be able to predict positioning of the microwave applicators to optimize treatment planning and provide for reproducible treatment set-up. We present a configuration of 3 applicators subtended by an equilateral triangle in order to target and relocate a 'hot spot' for improved treatment of deep tumors. A simple geometric analysis is illustrated. The microwave beam absorption profile, from the three power sources, was obtained from phantom studies depicting the radiative heat pattern for the triapplicator system (TRIPAS). A complex mathematical model was developed to demonstrate interaction of the beams in the medium. It was observed empirically that under coherent propagation in the near field electromagnetic (EM) waves tend to add at the center, while varying the propagation axial focal length caused a relocation of the summing focal points. Mathematical prediction correlated very well with the phantom studies. SAR values above 100 W/kg were achieved at 12.5 cm phantom depth, creating a relocatable 'hot spot' at the concentric foci of the 3 air cooled horn microwave applicators operating at 300 MHz.

  3. Cortical hot spots and labyrinths: why cortical neuromodulation for episodic migraine with aura should be personalized

    PubMed Central

    Dahlem, Markus A.; Schmidt, Bernd; Bojak, Ingo; Boie, Sebastian; Kneer, Frederike; Hadjikhani, Nouchine; Kurths, Jürgen

    2015-01-01

    Stimulation protocols for medical devices should be rationally designed. For episodic migraine with aura we outline model-based design strategies toward preventive and acute therapies using stereotactic cortical neuromodulation. To this end, we regard a localized spreading depression (SD) wave segment as a central element in migraine pathophysiology. To describe nucleation and propagation features of the SD wave segment, we define the new concepts of cortical hot spots and labyrinths, respectively. In particular, we firstly focus exclusively on curvature-induced dynamical properties by studying a generic reaction-diffusion model of SD on the folded cortical surface. This surface is described with increasing level of details, including finally personalized simulations using patient's magnetic resonance imaging (MRI) scanner readings. At this stage, the only relevant factor that can modulate nucleation and propagation paths is the Gaussian curvature, which has the advantage of being rather readily accessible by MRI. We conclude with discussing further anatomical factors, such as areal, laminar, and cellular heterogeneity, that in addition to and in relation to Gaussian curvature determine the generalized concept of cortical hot spots and labyrinths as target structures for neuromodulation. Our numerical simulations suggest that these target structures are like fingerprints, they are individual features of each migraine sufferer. The goal in the future will be to provide individualized neural tissue simulations. These simulations should predict the clinical data and therefore can also serve as a test bed for exploring stereotactic cortical neuromodulation. PMID:25798103

  4. Lack of Mutational Hot Spots during Decitabine-Mediated HIV-1 Mutagenesis

    PubMed Central

    Rawson, Jonathan M. O.; Landman, Sean R.; Reilly, Cavan S.; Bonnac, Laurent; Patterson, Steven E.

    2015-01-01

    Decitabine has previously been shown to induce lethal mutagenesis of human immunodeficiency virus type 1 (HIV-1). However, the factors that determine the susceptibilities of individual sequence positions in HIV-1 to decitabine have not yet been defined. To investigate this, we performed Illumina high-throughput sequencing of multiple amplicons prepared from proviral DNA that was recovered from decitabine-treated cells infected with HIV-1. We found that decitabine induced an ≈4.1-fold increase in the total mutation frequency of HIV-1, primarily due to a striking ≈155-fold increase in the G-to-C transversion frequency. Intriguingly, decitabine also led to an ≈29-fold increase in the C-to-G transversion frequency. G-to-C frequencies varied substantially (up to ≈80-fold) depending upon sequence position, but surprisingly, mutational hot spots (defined as upper outliers within the mutation frequency distribution) were not observed. We further found that every single guanine position examined was significantly susceptible to the mutagenic effects of decitabine. Taken together, these observations demonstrate for the first time that decitabine-mediated HIV-1 mutagenesis is promiscuous and occurs in the absence of a clear bias for mutational hot spots. These data imply that decitabine-mediated G-to-C mutagenesis is a highly effective antiviral mechanism for extinguishing HIV-1 infectivity. PMID:26282416

  5. Magnetohydrodynamic solution for a Z pinch showing the production of a hot spot

    NASA Astrophysics Data System (ADS)

    Maxon, S.; Hammer, J. H.; Eddleman, J. L.; Tabak, M.; Zimmerman, G. B.; Alley, W. E.; Estabrook, K. G.; Harte, J. A.; Nash, T. J.; Sanford, T. W. L.; De Groot, J. S.

    1996-05-01

    Two-dimensional LASNEX [National Technical Information Service Document No. DE 81026329 (Zimmerman, Report No. UCRL-74811, 1973)] calculations are made for a Z pinch on Saturn, the low-impedance, low-inductance electron accelerator at the Sandia National Laboratories [D. D. Bloomquist et al. Proceedings of the Sixth IEEE Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (Institute of Electronics and Electrical Engineers, New York, 1987), p. 310]. The experiment is characterized by a current of 6 MA with a tungsten wire load (4 mg) at 2 mm. Two-dimensional calculations show the evolution of the Rayleigh-Taylor instability to the bubble and spike phase, causing high-density islands to form in the pinch opposite the bubbles. The two-dimensional energy flow causes a ``hot spot'' to evolve, which is shown to agree in its size and brightness with pinhole camera measurements. This is the first explicit calculation of a hot spot in two dimensions employing the full magnetohydrodynamic equations.

  6. Magnetohydrodynamic solution for a Z pinch showing the production of a hot spot

    SciTech Connect

    Maxon, S.; Hammer, J.H.; Eddleman, J.L.; Tabak, M.; Zimmerman, G.B.; Alley, W.E.; Estabrook, K.G.; Harte, J.A.; Nash, T.J.; Sanford, T.W.; De Groot, J.S.

    1996-05-01

    Two-dimensional LASNEX [National Technical Information Service Document No. DE 81026329 (Zimmerman, Report No. UCRL-74811, 1973)] calculations are made for a Z pinch on Saturn, the low-impedance, low-inductance electron accelerator at the Sandia National Laboratories [D. D. Bloomquist {ital et} {ital al}. {ital Proceedings} {ital of} {ital the} {ital Sixth} {ital IEEE} {ital Pulsed} {ital Power} {ital Conference}, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (Institute of Electronics and Electrical Engineers, New York, 1987), p. 310]. The experiment is characterized by a current of 6 MA with a tungsten wire load (4 mg) at 2 mm. Two-dimensional calculations show the evolution of the Rayleigh{endash}Taylor instability to the bubble and spike phase, causing high-density islands to form in the pinch opposite the bubbles. The two-dimensional energy flow causes a {open_quote}{open_quote}hot spot{close_quote}{close_quote} to evolve, which is shown to agree in its size and brightness with pinhole camera measurements. This is the first explicit calculation of a hot spot in two dimensions employing the full magnetohydrodynamic equations. {copyright} {ital 1996 American Institute of Physics.}

  7. Self-assembled large Au nanoparticle arrays with regular hot spots for SERS.

    SciTech Connect

    Chen, A.; DePrince III, A. E.; Demortiere, A.; Joshi-Imre, A.; Shevchenko, E. V.; Gray, S.K.; Welp, U.; Vlasko-Vlasov, V. K.

    2011-08-22

    The cost-effective self-assembly of 80 nm Au nanoparticles (NPs) into large-domain, hexagonally close-packed arrays for high-sensitivity and high-fidelity surface-enhanced Raman spectroscopy (SERS) is demonstrated. These arrays exhibit specific optical resonances due to strong interparticle coupling, which are well reproduced by finite-difference time-domain (FDTD) simulations. The gaps between NPs form a regular lattice of hot spots that enable a large amplification of both photoluminescence and Raman signals. At smaller wavelengths the hot spots are extended away from the minimum-gap positions, which allows SERS of larger analytes that do not fit into small gaps. Using CdSe quantum dots (QDs) a 3-5 times larger photoluminescence enhancement than previously reported is experimentally demonstrated and an unambiguous estimate of the electromagnetic SERS enhancement factor of {approx}10{sup 4} is obtained by direct scanning electron microscopy imaging of QDs responsible for the Raman signal. Much stronger enhancement of {approx}10{sup 8} is obtained at larger wavelengths for benzenethiol molecules penetrating the NP gaps.

  8. Surface plasmon delocalization in silver nanoparticle aggregates revealed by subdiffraction supercontinuum hot spots

    PubMed Central

    Borys, Nicholas J.; Shafran, Eyal; Lupton, John M.

    2013-01-01

    The plasmonic resonances of nanostructured silver films produce exceptional surface enhancement, enabling reproducible single-molecule Raman scattering measurements. Supporting a broad range of plasmonic resonances, these disordered systems are difficult to investigate with conventional far-field spectroscopy. Here, we use nonlinear excitation spectroscopy and polarization anisotropy of single optical hot spots of supercontinuum generation to track the transformation of these plasmon modes as the mesoscopic structure is tuned from a film of discrete nanoparticles to a semicontinuous layer of aggregated particles. We demonstrate how hot spot formation from diffractively-coupled nanoparticles with broad spectral resonances transitions to that from spatially delocalized surface plasmon excitations, exhibiting multiple excitation resonances as narrow as 13 meV. Photon-localization microscopy reveals that the delocalized plasmons are capable of focusing multiple narrow radiation bands over a broadband range to the same spatial region within 6 nm, underscoring the existence of novel plasmonic nanoresonators embedded in highly disordered systems. PMID:23807624

  9. Confining hot spots in 3C 196 - Implications for QSO-companion galaxies

    NASA Technical Reports Server (NTRS)

    Brown, R. L.; Broderick, J. J.; Mitchell, K. J.

    1986-01-01

    VLBI observations of the extremely compact hot spot in the northern radio lobe of the QSO 3C 196 reveal the angular size of its smallest substructure to be 0.065 arcsec x 0.045 arcsec or about 300 pc at the redshift distance. The morphology of the hot spot and its orientation relative to the more diffuse radio emission suggest that it is formed by an oblique interaction between the nuclear QSO jet and circum-QSO cloud. The inferred density in this cloud, together with its apparent size, imply that the cloud contains a galactic mass, greater than a billion solar masses of gas. The effect of the jet will be to hasten gravitational collapse of the cloud. If many QSOs such as 3C 196 are formed or found in gas-rich environments, the QSO radio phase may commonly stimulate the metamorphosis of circum-QSO gas to QSO-companion galaxies or it may play a significant part in catalyzing star formation in existing companions.

  10. Confining hot spots in 3C 196 - implications for QSO-companion galaxies

    SciTech Connect

    Brown, R.L.; Broderick, J.J.; Mitchell, K.J.

    1986-07-01

    VLBI observations of the extremely compact hot spot in the northern radio lobe of the QSO 3C 196 reveal the angular size of its smallest substructure to be 0.065 arcsec x 0.045 arcsec or about 300 pc at the redshift distance. The morphology of the hot spot and its orientation relative to the more diffuse radio emission suggest that it is formed by an oblique interaction between the nuclear QSO jet and circum-QSO cloud. The inferred density in this cloud, together with its apparent size, imply that the cloud contains a galactic mass, greater than a billion solar masses of gas. The effect of the jet will be to hasten gravitational collapse of the cloud. If many QSOs such as 3C 196 are formed or found in gas-rich environments, the QSO radio phase may commonly stimulate the metamorphosis of circum-QSO gas to QSO-companion galaxies or it may play a significant part in catalyzing star formation in existing companions. 30 references.

  11. Hot-spot tectonics of Eistla Regio, Venus: Results from Magellan images and Pioneer Venus gravity

    NASA Astrophysics Data System (ADS)

    Grimm, Robert E.; Phillips, Roger J.

    1991-06-01

    Eistla Regio (ER) is a broad, low, discontinuous topographic rise striking roughly EW at low northern latitudes of Venus. Some 2000 x 7000 km in dimensions, it is the third largest rise in planform on Venus after Aphrodite Terra and Beta Phoebe Regiones. These rises are the key physiographic elements in a hot spot model of global tectonics including transient plume behavior. Since ER is the first such rise viewed by Magellan and the latitude is very favorable for Pioneer Venus gravity studies, some of the predictions of a time dependent hot spot model are tested. Western ER is defined as the rise including Gula and Sif Mons and central ER as that including Sappho Patera. Superior conjunction prevented Magellan from returning data on eastern ER (Pavlova) during the first mapping cycle. It is concluded that the western and central portions of ER, while part of the same broad topographic rise and tectonic framework, have distinctly different surface ages and gravity signatures. The western rise, including Gula and Sif Mons, is the expression of deep seated uplift with volcanism limited to the individual large shields. The eastern portion has been widely resurfaced more recently by thermal anomalies in the mantle.

  12. Hot-spot tectonics of Eistla Regio, Venus: Results from Magellan images and Pioneer Venus gravity

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.; Phillips, Roger J.

    1991-01-01

    Eistla Regio (ER) is a broad, low, discontinuous topographic rise striking roughly EW at low northern latitudes of Venus. Some 2000 x 7000 km in dimensions, it is the third largest rise in planform on Venus after Aphrodite Terra and Beta Phoebe Regiones. These rises are the key physiographic elements in a hot spot model of global tectonics including transient plume behavior. Since ER is the first such rise viewed by Magellan and the latitude is very favorable for Pioneer Venus gravity studies, some of the predictions of a time dependent hot spot model are tested. Western ER is defined as the rise including Gula and Sif Mons and central ER as that including Sappho Patera. Superior conjunction prevented Magellan from returning data on eastern ER (Pavlova) during the first mapping cycle. It is concluded that the western and central portions of ER, while part of the same broad topographic rise and tectonic framework, have distinctly different surface ages and gravity signatures. The western rise, including Gula and Sif Mons, is the expression of deep seated uplift with volcanism limited to the individual large shields. The eastern portion has been widely resurfaced more recently by thermal anomalies in the mantle.

  13. The radio sources CTA 21 and OF+247: The hot spots of radio galaxies

    NASA Astrophysics Data System (ADS)

    Artyukh, V. S.; Tyul'bashev, S. A.; Chernikov, P. A.

    2013-06-01

    The physical conditions in the radio sources CTA 21 and OF+247 are studied assuming that the low-frequency spectral turnovers are due to synchrotron self-absorption. The physical parameters of the radio sources are estimated using a technique based on a nonuniform synchrotron source model. It is shown that the magnetic-field distributions in the dominant compact components of these radio sources are strongly inhomogeneous. The magnetic fields at the center of the sources are B ˜ 10-1 G, and the fields are two to three orders of magnitude weaker at the periphery. The magnetic field averaged over the compact component is B ˜ 10-3 G, and the density of relativistic electrons is n e ˜ 10-3 cm-3. Assuming that there is equipartition of the energies of the magnetic field and relativistic particles, averaged over the source, < E H > = < E e > ˜ 10-7-10-6 erg cm-3. The energy density of the magnetic field exceeds that of the relativistic electrons at the centers of the radio sources. The derived parameters of CTA 21 and OF+247 are close to those of the hot spots in the radio galaxy Cygnus A. On this basis, it is suggested that CTA 21 and OF+247 are radio galaxies at an early stage of their evolution, when the hot spots (dominant compact radio components) have appeared, and the radio lobes (weak extended components) are still being formed.

  14. Deep-sea hydrothermal vents: potential hot spots for natural products discovery?

    PubMed

    Thornburg, Christopher C; Zabriskie, T Mark; McPhail, Kerry L

    2010-03-26

    Deep-sea hydrothermal vents are among the most extreme and dynamic environments on Earth. However, islands of highly dense and biologically diverse communities exist in the immediate vicinity of hydrothermal vent flows, in stark contrast to the surrounding bare seafloor. These communities comprise organisms with distinct metabolisms based on chemosynthesis and growth rates comparable to those from shallow water tropical environments, which have been rich sources of biologically active natural products. The geological setting and geochemical nature of deep-sea vents that impact the biogeography of vent organisms, chemosynthesis, and the known biological and metabolic diversity of Eukarya, Bacteria, and Archaea, including the handful of natural products isolated to date from deep-sea vent organisms, are considered here in an assessment of deep-sea hydrothermal vents as potential hot spots for natural products investigations. Of critical importance too are the logistics of collecting deep vent organisms, opportunities for re-collection considering the stability and longevity of vent sites, and the ability to culture natural product-producing deep vent organisms in the laboratory. New cost-effective technologies in deep-sea research and more advanced molecular techniques aimed at screening a more inclusive genetic assembly are poised to accelerate natural product discoveries from these microbial diversity hot spots.

  15. Sensitivity of inertial confinement fusion hot spot properties to the deuterium-tritium fuel adiabat

    SciTech Connect

    Melvin, J.; Lim, H.; Rana, V.; Glimm, J.; Cheng, B.; Sharp, D. H.; Wilson, D. C.

    2015-02-15

    We determine the dependence of key Inertial Confinement Fusion (ICF) hot spot simulation properties on the deuterium-tritium fuel adiabat, here modified by addition of energy to the cold shell. Variation of this parameter reduces the simulation to experiment discrepancy in some, but not all, experimentally inferred quantities. Using simulations with radiation drives tuned to match experimental shots N120321 and N120405 from the National Ignition Campaign (NIC), we carry out sets of simulations with varying amounts of added entropy and examine the sensitivities of important experimental quantities. Neutron yields, burn widths, hot spot densities, and pressures follow a trend approaching their experimentally inferred quantities. Ion temperatures and areal densities are sensitive to the adiabat changes, but do not necessarily converge to their experimental quantities with the added entropy. This suggests that a modification to the simulation adiabat is one of, but not the only explanation of the observed simulation to experiment discrepancies. In addition, we use a theoretical model to predict 3D mix and observe a slight trend toward less mixing as the entropy is enhanced. Instantaneous quantities are assessed at the time of maximum neutron production, determined dynamically within each simulation. These trends contribute to ICF science, as an effort to understand the NIC simulation to experiment discrepancy, and in their relation to the high foot experiments, which features a higher adiabat in the experimental design and an improved neutron yield in the experimental results.

  16. An ancient retrovirus-like element contains hot spots for SINE insertion.

    PubMed Central

    Cantrell, M A; Filanoski, B J; Ingermann, A R; Olsson, K; DiLuglio, N; Lister, Z; Wichman, H A

    2001-01-01

    Vertebrate retrotransposons have been used extensively for phylogenetic analyses and studies of molecular evolution. Information can be obtained from specific inserts either by comparing sequence differences that have accumulated over time in orthologous copies of that insert or by determining the presence or absence of that specific element at a particular site. The presence of specific copies has been deemed to be an essentially homoplasy-free phylogenetic character because the probability of multiple independent insertions into any one site has been believed to be nil. Mys elements are a type of LTR-containing retrotransposon present in Sigmodontine rodents. In this study we have shown that one particular insert, mys-9, is an extremely old insert present in multiple species of the genus Peromyscus. We have found that different copies of this insert show a surprising range of sizes, due primarily to a continuing series of SINE (short interspersed element) insertions into this locus. We have identified two hot spots for SINE insertion within mys-9 and at each hot spot have found that two independent SINE insertions have occurred at identical sites. These results have major repercussions for phylogenetic analyses based on SINE insertions, indicating the need for caution when one concludes that the existence of a SINE at a specific locus in multiple individuals is indicative of common ancestry. Although independent insertions at the same locus may be rare, SINE insertions are not homoplasy-free phylogenetic markers. PMID:11404340

  17. Wood ant nests as hot spots of microbial activity in forest ecosystems

    NASA Astrophysics Data System (ADS)

    Jilkova, Veronika; Frouz, Jan

    2015-04-01

    Wood ants build large and long-lasting nests from organic materials and mineral soil which have a very special structure. Nests are well-aerated due to numerous chambers and galleries and stable temperature and moisture are maintained there thanks to ant activities. These conditions together with the constant input of easily available nutrients from food of ants support microbial activity. Due to respiration of ants and microbes, wood ant nests are known as hot spots of CO2 production in forest ecosystems. Although the main source of CO2 is represented by ant respiration, a significant amount of CO2 originates also from microbial decomposition of organic materials. Several conditions affect microbial respiration, such as moisture of nest material, changes in temperatures or food input. As mineral nutrients are released from organic materials, wood ant nests represent hot spots of mineral nutrients in forest ecosystems which can be exploited by other organisms, such as roots of trees, and can also cause heterogeneity in species abundance and composition.

  18. Cortical hot spots and labyrinths: why cortical neuromodulation for episodic migraine with aura should be personalized.

    PubMed

    Dahlem, Markus A; Schmidt, Bernd; Bojak, Ingo; Boie, Sebastian; Kneer, Frederike; Hadjikhani, Nouchine; Kurths, Jürgen

    2015-01-01

    Stimulation protocols for medical devices should be rationally designed. For episodic migraine with aura we outline model-based design strategies toward preventive and acute therapies using stereotactic cortical neuromodulation. To this end, we regard a localized spreading depression (SD) wave segment as a central element in migraine pathophysiology. To describe nucleation and propagation features of the SD wave segment, we define the new concepts of cortical hot spots and labyrinths, respectively. In particular, we firstly focus exclusively on curvature-induced dynamical properties by studying a generic reaction-diffusion model of SD on the folded cortical surface. This surface is described with increasing level of details, including finally personalized simulations using patient's magnetic resonance imaging (MRI) scanner readings. At this stage, the only relevant factor that can modulate nucleation and propagation paths is the Gaussian curvature, which has the advantage of being rather readily accessible by MRI. We conclude with discussing further anatomical factors, such as areal, laminar, and cellular heterogeneity, that in addition to and in relation to Gaussian curvature determine the generalized concept of cortical hot spots and labyrinths as target structures for neuromodulation. Our numerical simulations suggest that these target structures are like fingerprints, they are individual features of each migraine sufferer. The goal in the future will be to provide individualized neural tissue simulations. These simulations should predict the clinical data and therefore can also serve as a test bed for exploring stereotactic cortical neuromodulation.

  19. Identifying geographic hot spots of reassortment in a multipartite plant virus

    PubMed Central

    Savory, Fiona R; Varma, Varun; Ramakrishnan, Uma

    2014-01-01

    Reassortment between different species or strains plays a key role in the evolution of multipartite plant viruses and can have important epidemiological implications. Identifying geographic locations where reassortant lineages are most likely to emerge could be a valuable strategy for informing disease management and surveillance efforts. We developed a predictive framework to identify potential geographic hot spots of reassortment based upon spatially explicit analyses of genome constellation diversity. To demonstrate the utility of this approach, we examined spatial variation in the potential for reassortment among Cardamom bushy dwarf virus (CBDV; Nanoviridae, Babuvirus) isolates in Northeast India. Using sequence data corresponding to six discrete genome components for 163 CBDV isolates, a quantitative measure of genome constellation diversity was obtained for locations across the sampling region. Two key areas were identified where viruses with highly distinct genome constellations cocirculate, and these locations were designated as possible geographic hot spots of reassortment, where novel reassortant lineages could emerge. Our study demonstrates that the potential for reassortment can be spatially dependent in multipartite plant viruses and highlights the use of evolutionary analyses to identify locations which could be actively managed to facilitate the prevention of outbreaks involving novel reassortant strains. PMID:24944570

  20. Non-local Lateral electron heat transport from one or more hot spots.

    NASA Astrophysics Data System (ADS)

    Matte, Jean-Pierre; Alouani-Bibi, Fathallah

    2000-10-01

    Fokker-Planck simulations of collisional absorption and transport in long scale length, preformed, underdense plasmas heated by intense and narrow laser hot spots, as in certain recent LANL experiments [1], are presented. The temperature profiles compared with those obtained from flux limited or delocalized heat flow models. For the former, the temperature peaks can be matched only if a very low flux limiter is used, and even then, the scale length of the temperature profile is always overestimated. The electron distribution function will be characterized, and compared to the "DLM" shape, exp(-(v/u)^m), [2] and the best fit for m will be compared to older formulas for uniform plasmas [2]. Hydrodynamic effects are also addressed with simulations which include ion motion; both with and without the ponderomotive force. The enhancement of sound velocity due to the "DLM" shape [3] inside the hot spot will be quantified. [1] J.A. Cobble et al., Phys. Plasmas, 7, 323 (2000) [2] J.P. Matte et al., Plasma Phys. and Contr. Fusion, 30, 1665, (1988) [3] B. B. Afeyan et al., PRL 81, 2322 (1998).

  1. Biofilm models for the food industry: hot spots for plasmid transfer?

    PubMed

    Van Meervenne, Eva; De Weirdt, Rosemarie; Van Coillie, Els; Devlieghere, Frank; Herman, Lieve; Boon, Nico

    2014-04-01

    Biofilms represent a substantial problem in the food industry, with food spoilage, equipment failure, and public health aspects to consider. Besides, biofilms may be a hot spot for plasmid transfer, by which antibiotic resistance can be disseminated to potential foodborne pathogens. This study investigated biomass and plasmid transfer in dual-species (Pseudomonas putida and Escherichia coli) biofilm models relevant to the food industry. Two different configurations (flow-through and drip-flow) and two different inoculation procedures (donor-recipient and recipient-donor) were tested. The drip-flow configuration integrated stainless steel coupons in the setup while the flow-through configuration included a glass flow cell and silicone tubing. The highest biomass density [10 log (cells cm-²)] was obtained in the silicone tubing when first the recipient strain was inoculated. High plasmid transfer ratios, up to 1/10 (transconjugants/total bacteria), were found. Depending on the order of inoculation, a difference in transfer efficiency between the biofilm models could be found. The ease by which the multiresistance plasmid was transferred highlights the importance of biofilms in the food industry as hot spots for the acquisition of multiresistance plasmids. This can impede the treatment of foodborne illnesses if pathogens acquire this multiresistance in or from the biofilm.

  2. A conserved TLR5 binding and activation hot spot on flagellin

    PubMed Central

    Song, Wan Seok; Jeon, Ye Ji; Namgung, Byeol; Hong, Minsun; Yoon, Sung-il

    2017-01-01

    Flagellin is a bacterial protein that polymerizes into the flagellar filament and is essential for bacterial motility. When flagellated bacteria invade the host, flagellin is recognized by Toll-like receptor 5 (TLR5) as a pathogen invasion signal and eventually evokes the innate immune response. Here, we provide a conserved structural mechanism by which flagellins from Gram-negative γ-proteobacteria and Gram-positive Firmicutes bacteria bind and activate TLR5. The comparative structural analysis using our crystal structure of a complex between Bacillus subtilis flagellin (bsflagellin) and TLR5 at 2.1 Å resolution, combined with the alanine scanning analysis of the binding interface, reveals a common hot spot in flagellin for TLR5 activation. An arginine residue (bsflagellin R89) of the flagellin D1 domain and its adjacent residues (bsflagellin E114 and L93) constitute a hot spot that provides shape and chemical complementarity to a cavity generated by the loop of leucine-rich repeat 9 in TLR5. In addition to the flagellin D1 domain, the D0 domain also contributes to TLR5 activity through structurally dispersed regions, but not a single focal area. These results establish the groundwork for the future design of flagellin-based therapeutics. PMID:28106112

  3. Superconductivity mediated by quantum critical antiferromagnetic fluctuations: The rise and fall of hot spots

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoyu; Schattner, Yoni; Berg, Erez; Fernandes, Rafael M.

    2017-05-01

    In several unconventional superconductors, the highest superconducting transition temperature Tc is found in a region of the phase diagram where the antiferromagnetic transition temperature extrapolates to zero, signaling a putative quantum critical point. The elucidation of the interplay between these two phenomena—high-Tc superconductivity and magnetic quantum criticality—remains an important piece of the complex puzzle of unconventional superconductivity. In this paper, we combine sign-problem-free quantum Monte Carlo simulations and field-theoretical analytical calculations to unveil the microscopic mechanism responsible for the superconducting instability of a general low-energy model, called the spin-fermion model. In this approach, low-energy electronic states interact with each other via the exchange of quantum critical magnetic fluctuations. We find that even in the regime of moderately strong interactions, both the superconducting transition temperature and the pairing susceptibility are governed not by the properties of the entire Fermi surface, but instead by the properties of small portions of the Fermi surface called hot spots. Moreover, Tc increases with increasing interaction strength, until it starts to saturate at the crossover from hot-spots-dominated to Fermi-surface-dominated pairing. Our work provides not only invaluable insights into the system parameters that most strongly affect Tc, but also important benchmarks to assess the origin of superconductivity in both microscopic models and actual materials.

  4. A physically-based Mie–Gruneisen equation of state to determine hot spot temperature distributions

    SciTech Connect

    Kittell, David Erik; Yarrington, Cole Davis

    2016-07-14

    Here, a physically-based form of the Mie–Grüneisen equation of state (EOS) is derived for calculating 1d planar shock temperatures, as well as hot spot temperature distributions from heterogeneous impact simulations. This form utilises a multi-term Einstein oscillator model for specific heat, and is completely algebraic in terms of temperature, volume, an integrating factor, and the cold curve energy. Moreover, any empirical relation for the reference pressure and energy may be substituted into the equations via the use of a generalised reference function. The complete EOS is then applied to calculations of the Hugoniot temperature and simulation of hydrodynamic pore collapse using data for the secondary explosive, hexanitrostilbene (HNS). From these results, it is shown that the choice of EOS is even more significant for determining hot spot temperature distributions than planar shock states. The complete EOS is also compared to an alternative derivation assuming that specific heat is a function of temperature alone, i.e. cv(T). Temperature discrepancies on the order of 100–600 K were observed corresponding to the shock pressures required to initiate HNS (near 10 GPa). Overall, the results of this work will improve confidence in temperature predictions. By adopting this EOS, future work may be able to assign physical meaning to other thermally sensitive constitutive model parameters necessary to predict the shock initiation and detonation of heterogeneous explosives.

  5. Grain-Scale Simulations of Hot-Spot Initiation for Shocked TATB

    SciTech Connect

    Najjar, F; Howard, W; Fried, L

    2009-07-31

    High-explosive (HE) material consists of large-sized grains with micron-sized embedded impurities and pores. Under various mechanical/thermal insults, these pores collapse generating high-temperature regions leading to ignition. A computational study has been performed to investigate the mechanisms of pore collapse and hot spot initiation in TATB crystals, employing the thermohydrodynamics arbitrary-Lagrange-Eulerian code ALE3D. This initial study includes non-reactive dynamics to isolate the thermal and hydrodynamical effects. Two-dimensional high-resolution large-scale meso-scale simulations have been undertaken. We study an axisymmetric configuration for pore radii ranging from 0.5 to 2{micro}m, with initial shock pressures in the range from 3 to 11 GPa. A Mie-Gruneisen Equation of State (EOS) model is used for TATB, and includes a constant yield strength and shear modulus; while the air in the pore invokes a Livermore Equation of State (LEOS) model. The parameter space is systematically studied by considering various shock strengths, pore diameters and material properties. We find that thermal diffusion from the collapsed pores has an important effect in generating high-temperature hot spots in the TATB.

  6. Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

    NASA Astrophysics Data System (ADS)

    Juang, Jia-Yang; Zheng, Jinglin

    2016-10-01

    Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

  7. Ignition conditions relaxation for central hot-spot ignition with an ion-electron non-equilibrium model

    NASA Astrophysics Data System (ADS)

    Fan, Zhengfeng; Liu, Jie

    2016-10-01

    We present an ion-electron non-equilibrium model, in which the hot-spot ion temperature is higher than its electron temperature so that the hot-spot nuclear reactions are enhanced while energy leaks are considerably reduced. Theoretical analysis shows that the ignition region would be significantly enlarged in the hot-spot rhoR-T space as compared with the commonly used equilibrium model. Simulations show that shocks could be utilized to create and maintain non-equilibrium conditions within the hot spot, and the hot-spot rhoR requirement is remarkably reduced for achieving self-heating. In NIF high-foot implosions, it is observed that the x-ray enhancement factors are less than unity, which is not self-consistent and is caused by assuming Te =Ti. And from this non-consistency, we could infer that ion-electron non-equilibrium exists in the high-foot implosions and the ion temperature could be 9% larger than the equilibrium temperature.

  8. Effects of Long- and Intermediate-Wavelength Nonuniformities on Hot-Spot Energetics of Hydrodynamic Equivalent Targets

    NASA Astrophysics Data System (ADS)

    Bose, A.; Betti, R.; Woo, K. M.; Christopherson, A. R.; Shvarts, D.

    2015-11-01

    The impact of intermediate- and low-mode nonuniformities on the performance of inertial confinement fusion (ICF) implosions is investigated by a detailed study of hot-spot energetics. It is found that low- (1 ~ 2) and intermediate-mode (1 >= 10) asymmetries affect the hot-spot hydrodynamics in very different ways. It is observed that for low-mode asymmetries, the fusion yield decreases because of a significant reduction in hot-spot pressure while the neutron-averaged hot-spot volume remains comparable to that of unperturbed (clean) simulations. On the other hand, implosions with moderate-amplitude, intermediate-wavelength modes, which are amplified by the Rayleigh-Taylor instability (RTI), exhibit a fusion-yield degradation primarily caused by a reduction in the burn volume without significant degradation of the pressure. For very large amplitudes, the intermediate modes show a ``secondary piston effect,'' where the converging RTI spikes compress a much smaller volume, allowing for a secondary conversion of the shell's kinetic energy to internal energy at a central region. Understanding the effects of nonuniformities on the hot-spot energetics provides valuable insight in determining the causes of performance degradation in current ICF experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

  9. Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice

    PubMed Central

    de Boer, Esther; Jasin, Maria; Keeney, Scott

    2015-01-01

    Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. PMID:26251527

  10. Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice.

    PubMed

    de Boer, Esther; Jasin, Maria; Keeney, Scott

    2015-08-15

    Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency.

  11. HotSpot Wizard 2.0: automated design of site-specific mutations and smart libraries in protein engineering.

    PubMed

    Bendl, Jaroslav; Stourac, Jan; Sebestova, Eva; Vavra, Ondrej; Musil, Milos; Brezovsky, Jan; Damborsky, Jiri

    2016-07-08

    HotSpot Wizard 2.0 is a web server for automated identification of hot spots and design of smart libraries for engineering proteins' stability, catalytic activity, substrate specificity and enantioselectivity. The server integrates sequence, structural and evolutionary information obtained from 3 databases and 20 computational tools. Users are guided through the processes of selecting hot spots using four different protein engineering strategies and optimizing the resulting library's size by narrowing down a set of substitutions at individual randomized positions. The only required input is a query protein structure. The results of the calculations are mapped onto the protein's structure and visualized with a JSmol applet. HotSpot Wizard lists annotated residues suitable for mutagenesis and can automatically design appropriate codons for each implemented strategy. Overall, HotSpot Wizard provides comprehensive annotations of protein structures and assists protein engineers with the rational design of site-specific mutations and focused libraries. It is freely available at http://loschmidt.chemi.muni.cz/hotspotwizard. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  12. Presence of a thermoregulatory hot spot in the prothorax of the large carpenter bee and the bumble bee.

    PubMed

    Volynchik, Stanislav; Plotkin, Marian; Ermakov, Natalya Y; Bergman, David J; Ishay, Jacob S

    2006-11-01

    In both the large carpenter bee (Xylocopa pubescens) and the bumblebee (Bombus terrestris), a hot spot was detected in the center of the prothorax on its dorsal-external aspect. In both cases, the temperature in this hot spot was found to be greater than the ambient temperature and that at the tip of the gaster. In B. terrestris, it was higher by 9-10 degrees C from that at the gaster tip and by 15-16 degrees C from the ambient temperature, while in X. pubescens the corresponding differences were 11-20 degrees C and 18-19 degrees C, respectively. The recorded thermal differences were not fixed but were rather variable, temporally as well as individually, but invariably all individuals measured showed these temperature differences. Furthermore, in none of the studied specimens was a hot spot detected in any part of the body other than the prothorax. From this hot spot in the prothorax, there is a cascade of temperatures in both directions, that is, anteriorly towards the head and posteriorly towards the gaster, with a graded drop in temperature in either direction. This article discusses possible reasons for the existence of such a hot spot in this particular location (the prothorax), its role or function, and its mode of operation. The authors speculate that it is a thermoregulatory center (for heating or cooling) that might be present in possibly all Hymenoptera that spend a considerable part of their life flying, regardless of whether they are social, parasocial, or solitary.

  13. HotSpot Wizard 2.0: automated design of site-specific mutations and smart libraries in protein engineering

    PubMed Central

    Bendl, Jaroslav; Stourac, Jan; Sebestova, Eva; Vavra, Ondrej; Musil, Milos; Brezovsky, Jan; Damborsky, Jiri

    2016-01-01

    HotSpot Wizard 2.0 is a web server for automated identification of hot spots and design of smart libraries for engineering proteins’ stability, catalytic activity, substrate specificity and enantioselectivity. The server integrates sequence, structural and evolutionary information obtained from 3 databases and 20 computational tools. Users are guided through the processes of selecting hot spots using four different protein engineering strategies and optimizing the resulting library's size by narrowing down a set of substitutions at individual randomized positions. The only required input is a query protein structure. The results of the calculations are mapped onto the protein's structure and visualized with a JSmol applet. HotSpot Wizard lists annotated residues suitable for mutagenesis and can automatically design appropriate codons for each implemented strategy. Overall, HotSpot Wizard provides comprehensive annotations of protein structures and assists protein engineers with the rational design of site-specific mutations and focused libraries. It is freely available at http://loschmidt.chemi.muni.cz/hotspotwizard. PMID:27174934

  14. Solar hot water system installed at Mobile, Alabama. Final report

    SciTech Connect

    1980-10-01

    This final report describes the solar energy hot water system installed at LaQuinta Motor Inn Inc., at Mobile, Alabama. The building is a 122 unit motel. The system consists of six rows of ten collectors and three rows of eleven collectors (1990 square feet) mounted on the roof. Griswald flow control valves were installed to regulate the flow to each row. Two Heliotrope electronic thermometers with a combined capability of measuring the temperatures of 22 different locations were installed for monitoring purposes. Engineering drawings, component specifications, and operator instructions are included.

  15. KFC2: a knowledge-based hot spot prediction method based on interface solvation, atomic density, and plasticity features.

    PubMed

    Zhu, Xiaolei; Mitchell, Julie C

    2011-09-01

    Hot spots constitute a small fraction of protein-protein interface residues, yet they account for a large fraction of the binding affinity. Based on our previous method (KFC), we present two new methods (KFC2a and KFC2b) that outperform other methods at hot spot prediction. A number of improvements were made in developing these new methods. First, we created a training data set that contained a similar number of hot spot and non-hot spot residues. In addition, we generated 47 different features, and different numbers of features were used to train the models to avoid over-fitting. Finally, two feature combinations were selected: One (used in KFC2a) is composed of eight features that are mainly related to solvent accessible surface area and local plasticity; the other (KFC2b) is composed of seven features, only two of which are identical to those used in KFC2a. The two models were built using support vector machines (SVM). The two KFC2 models were then tested on a mixed independent test set, and compared with other methods such as Robetta, FOLDEF, HotPoint, MINERVA, and KFC. KFC2a showed the highest predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.85); however, the false positive rate was somewhat higher than for other models. KFC2b showed the best predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.62) among all methods other than KFC2a, and the False Positive Rate (FPR = 0.15) was comparable with other highly predictive methods. Copyright © 2011 Wiley-Liss, Inc.

  16. Detection of direct and indirect noise generated by synthetic hot spots in a duct

    NASA Astrophysics Data System (ADS)

    De Domenico, Francesca; Rolland, Erwan O.; Hochgreb, Simone

    2017-04-01

    Sound waves in a combustor are generated from fluctuations in the heat release rate (direct noise) or the acceleration of entropy, vorticity or compositional perturbations through nozzles or turbine guide vanes (indirect or entropy noise). These sound waves are transmitted downstream as well as reflected upstream of the acceleration point, contributing to the overall noise emissions, or triggering combustion instabilities. Previous experiments attempted to isolate indirect noise by generating thermoacoustic hot spots electrically and measuring the transmitted acoustic waves, yet there are no measurements on the backward propagating entropy and acoustic waves. This work presents the first measurements which clearly separate the direct and indirect noise contributions to pressure fluctuations upstream of the acceleration point. Synthetic entropy spots are produced by unsteady electrical heating of a grid of thin wires located in a tube. Compression waves (direct noise) are generated from this heating process. The hot spots are then advected with the mean flow and finally accelerated through an orifice plate located at the end of the tube, producing a strong acoustic signature which propagates upstream (indirect noise). The convective time is selected to be longer than the heating pulse length, in order to obtain a clear time separation between direct and indirect noise in the overall pressure trace. The contribution of indirect noise to the overall noise is shown to be non-negligible either in subsonic or sonic throat conditions. However, the absolute amplitude of direct noise is larger than the corresponding fraction of indirect noise, explaining the difficulty in clearly identifying the two contributions when they are merged. Further, the work shows the importance of using appropriate pressure transducer instrumentation and correcting for the respective transfer functions in order to account for low frequency effects in the determination of pressure fluctuations.

  17. Imaging of spatially extended hot spots with coded apertures for intra-operative nuclear medicine applications

    NASA Astrophysics Data System (ADS)

    Kaissas, I.; Papadimitropoulos, C.; Potiriadis, C.; Karafasoulis, K.; Loukas, D.; Lambropoulos, C. P.

    2017-01-01

    Coded aperture imaging transcends planar imaging with conventional collimators in efficiency and Field of View (FOV). We present experimental results for the detection of 141 keV and 122 keV γ-photons emitted by uniformly extended 99mTc and 57Co hot-spots along with simulations of uniformly and normally extended 99mTc hot-spots. These results prove that the method can be used for intra-operative imaging of radio-traced sentinel nodes and thyroid remnants. The study is performed using a setup of two gamma cameras, each consisting of a coded-aperture (or mask) of Modified Uniformly Redundant Array (MURA) of rank 19 positioned on top of a CdTe detector. The detector pixel pitch is 350 μm and its active area is 4.4 × 4.4 cm2, while the mask element size is 1.7 mm. The detectable photon energy ranges from 15 keV up to 200 keV with an energy resolution of 3-4 keV FWHM. Triangulation is exploited to estimate the 3D spatial coordinates of the radioactive spots within the system FOV. Two extended sources, with uniform distributed activity (11 and 24 mm in diameter, respectively), positioned at 16 cm from the system and with 3 cm distance between their centers, can be resolved and localized with accuracy better than 5%. The results indicate that the estimated positions of spatially extended sources lay within their volume size and that neighboring sources, even with a low level of radioactivity, such as 30 MBq, can be clearly distinguished with an acquisition time about 3 seconds.

  18. The Cause of the Hot Spot in Vegetation Canopies and Soils: Shadow-Hiding Versus Coherent Backscatter

    NASA Technical Reports Server (NTRS)

    Hapke, Bruce; DiMucci, Dominick; Nelson, Robert; Smythe, William

    1996-01-01

    Two different mechanisms, shadow-hiding and coherent backscatter, can cause a hot spot, or opposition effect, in the bidirectional reflectance of vegetation and soils. Because the two mechanisms sample different properties, it is important to know which one is primarily responsible in a given medium. This question can be answered by measuring the bidirectional reflectance in circularly polarized light. If the results of the limited experiments reported here can be extrapolated to a wider range of materials, it appears that the primary cause of the hot spot in most vegetation canopies and in moist, clumpy soils is shadow-hiding. However, in vegetation with large numbers of wavelength-sized structures, such as mosses, and in dry, fine-grained soils, the hot spot is dominated by coherent backscatter.

  19. A reactive burn model for shock initiation in a PBX: scaling and separability based on the hot spot concept

    SciTech Connect

    Show, Milton S; Menikoff, Ralph

    2010-01-01

    In the formulation of a reactive burn model for shock initiation, we endeavor to incorporate a number of effects based on the underlying physical concept of hot spot ignition followed by the growth of reaction due to diverging deflagration fronts. The passage of a shock front sets the initial condition for reaction, leading to a fraction of the hot spots that completely burn while others will quench. The form of the rate model is chosen to incorporate approximations based on the physical picture. In particular, the approximations imply scaling relations that are then used to mathematically separate various contributions. That is, the model is modular and refinements can be applied separately without changing the other contributions. For example, the effect of initial temperature, porosity, etc. predominantly enter the characterization of the non-quenching hot spot distribution. A large collection of velocity gauge data is shown to be well represented by the model with a very small number of parameters.

  20. Detection of ligand binding hot spots on protein surfaces via fragment-based methods: application to DJ-1 and glucocerebrosidase

    SciTech Connect

    Landon, Melissa R.; Lieberman, Raquel L.; Hoang, Quyen Q.; Ju, Shulin; Caaveiro, Jose M.M.; Orwig, Susan D.; Kozakov, Dima; Brenke, Ryan; Chuang, Gwo-Yu; Beglov, Dmitry; Vajda, Sandor; Petsko, Gregory A.; Ringe, Dagmar

    2010-08-04

    The identification of hot spots, i.e., binding regions that contribute substantially to the free energy of ligand binding, is a critical step for structure-based drug design. Here we present the application of two fragment-based methods to the detection of hot spots for DJ-1 and glucocerebrosidase (GCase), targets for the development of therapeutics for Parkinson's and Gaucher's diseases, respectively. While the structures of these two proteins are known, binding information is lacking. In this study we employ the experimental multiple solvent crystal structures (MSCS) method and computational fragment mapping (FTMap) to identify regions suitable for the development of pharmacological chaperones for DJ-1 and GCase. Comparison of data derived via MSCS and FTMap also shows that FTMap, a computational method for the identification of fragment binding hot spots, is an accurate and robust alternative to the performance of expensive and difficult crystallographic experiments.

  1. How Similar Are Protein Folding and Protein Binding Nuclei? Examination of Vibrational Motions of Energy Hot Spots and Conserved Residues

    PubMed Central

    Haliloglu, Turkan; Keskin, Ozlem; Ma, Buyong; Nussinov, Ruth

    2005-01-01

    The underlying physico-chemical principles of the interactions between domains in protein folding are similar to those between protein molecules in binding. Here we show that conserved residues and experimental hot spots at intermolecular binding interfaces overlap residues that vibrate with high frequencies. Similarly, conserved residues and hot spots are found in protein cores and are also observed to vibrate with high frequencies. In both cases, these residues contribute significantly to the stability. Hence, these observations validate the proposition that binding and folding are similar processes. In both packing plays a critical role, rationalizing the residue conservation and the experimental alanine scanning hot spots. We further show that high-frequency vibrating residues distinguish between protein binding sites and the remainder of the protein surface. PMID:15596504

  2. Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data

    PubMed Central

    Kim, Sung-Min; Choi, Yosoon

    2017-01-01

    To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z-score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z-scores: high content with a high z-score (HH), high content with a low z-score (HL), low content with a high z-score (LH), and low content with a low z-score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1–4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required. PMID:28629168

  3. Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data.

    PubMed

    Kim, Sung-Min; Choi, Yosoon

    2017-06-18

    To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z-score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z-scores: high content with a high z-score (HH), high content with a low z-score (HL), low content with a high z-score (LH), and low content with a low z-score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1-4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required.

  4. Deep structure under Yellowstone National Park U.S.A.: A continental "hot spot"

    USGS Publications Warehouse

    Iyer, H.M.

    1979-01-01

    In order to understand the origin of long-lived loci of volcanism (sometimes called "hot spots") and their possible role in global tectonic processes, it is essential to know their deep structure. Even though some work has been done on the crustal, upper-mantle, and deep-mantle structure under some of these "hot spots", the picture is far from clear. In an attempt to study the structure under the Yellowstone National Park U.S.A., which is considered to be such a "hot spot", we recorded teleseisms using 26 telemetered seismic stations and three groups of portable stations. The network was operated within a 150 km radius centered on the Yellowstone caldera, the major, Quaternary volcanic feature of the Yellowstone region. Teleseismic delays of about 1.5 sec are found inside the caldera, and the delays remain high over a 100 km wide area around the caldera. The spatial distribution and magnitude of the delays indicate the presence of a large body of low-velocity material with horizontal dimensions corresponding approximately to the caldera size (40 km ?? 80 km) near the surface and extending to a depth of 200-250 km under the caldera. Using ray-tracing and inversion techniques, it is estimated that the compressional velocity inside the anomalous body is lower than in the surrounding rock by about 15% in the upper crust and by 5% in the lower crust and upper mantle. It is postulated that the body is partly composed of molten rock with a high degree of partial melting at shallow depths and is responsible for the observed Yellowstone volcanism. The large size of the partially molten body, taken together with its location at the head of a 350 km zone of volcanic propagation along the axis of the Snake River Plain, indicates that the volcanism associated with Yellowstone has its origin below the lithosphere and is relatively stationary with respect to plate motion. Using our techniques, we are unable to detect any measurable velocity contrast in the mantle beneath the low

  5. Ion-microprobe dating of zircon from quartz-graphite veins at the Bristol, New Hampshire, metamorphic hot spot

    SciTech Connect

    Zeitler, P.K. ); Barreiro, B.; Chamberlain, C.P. ); Rumble, D. III )

    1990-07-01

    Detrital zircons entrained in hydrothermal quartz-graphite-rutile veins found near the Bristol, New Hampshire, metamorphic hot spot are overgrown by thin rims. Ion-microprobe analyses of these rims date their growth at 408 {plus minus} 6 Ma. These measurements quantitatively confirm textural evidence that the graphite veins were emplaced during peak metamorphism associated with the Acadian orogeny, and they provide a direct positive test of the hypothesis, based on petrological and stable-isotope evidence, that the hydrothermal systems responsible for the quartz-graphite veins were also responsible for the hot-spot metamorphism.

  6. African hot spot volcanism: small-scale convection in the upper mantle beneath cratons.

    PubMed

    King, S D; Ritsema, J

    2000-11-10

    Numerical models demonstrate that small-scale convection develops in the upper mantle beneath the transition of thick cratonic lithosphere and thin oceanic lithosphere. These models explain the location and geochemical characteristics of intraplate volcanos on the African and South American plates. They also explain the presence of relatively high seismic shear wave velocities (cold downwellings) in the mantle transition zone beneath the western margin of African cratons and the eastern margin of South American cratons. Small-scale, edge-driven convection is an alternative to plumes for explaining intraplate African and South American hot spot volcanism, and small-scale convection is consistent with mantle downwellings beneath the African and South American lithosphere.

  7. Computational study of 3-D hot-spot initiation in shocked insensitive high-explosive

    NASA Astrophysics Data System (ADS)

    Najjar, F. M.; Howard, W. M.; Fried, L. E.; Manaa, M. R.; Nichols, A., III; Levesque, G.

    2012-03-01

    High-explosive (HE) material consists of large-sized grains with micron-sized embedded impurities and pores. Under various mechanical/thermal insults, these pores collapse generating hightemperature regions leading to ignition. A hydrodynamic study has been performed to investigate the mechanisms of pore collapse and hot spot initiation in TATB crystals, employing a multiphysics code, ALE3D, coupled to the chemistry module, Cheetah. This computational study includes reactive dynamics. Two-dimensional high-resolution large-scale meso-scale simulations have been performed. The parameter space is systematically studied by considering various shock strengths, pore diameters and multiple pore configurations. Preliminary 3-D simulations are undertaken to quantify the 3-D dynamics.

  8. Probing plasmonic hot spots on single gold nanowires using combined near-field techniques

    NASA Astrophysics Data System (ADS)

    Hsia, Patrick; Douillard, Ludovic; Charra, Fabrice; Marguet, Sylvie; Kostcheev, Sergei; Bachelot, Renaud J. B.; Fiorini-Debuisschert, Céline

    2015-08-01

    The plasmonic properties of individual gold nanowires (NW) have been investigated using both two-photon luminescence (2PL) coupled to atomic force microscopy (AFM) and photoemission electron microscopy (PEEM) associated to low-energy electron microscopy (LEEM) measurements. Using these complementary near-field characterization techniques, comparative studies between wires made either by colloidal chemistry (CC) or by e-beam lithography (EBL) have been undertaken towards a better understanding of the role of the wires crystallinity regarding its optical properties. Considering comparable excitation conditions, we show that wires made by colloidal synthesis exhibits quite similar field enhancement effects ("hot spots") as EBL NW, however their 2PL emission spectrum clearly reveals their crystalline properties.

  9. Hot spot and temperature analysis of shocked hydrocarbon polymer foams using molecular dynamics simulation

    SciTech Connect

    Lane, J. Matthew D.; Grest, Gary S.; Mattsson, Thomas R.

    2013-11-01

    Hydrocarbon polymers, foams and nanocomposites are increasingly being subjected to extreme environments. Molecular scale modeling of these materials offers insight into failure mechanisms and complex response. Prior classical molecular dynamics (MD) simulations of the principal shock Hugoniot for two hydrocarbon polymers, polyethylene (PE) and poly (4-methyl-1-pentene) (PMP) have shown good agreement with density functional theory (DFT) calculations and experiments conducted at Sandia National Laboratories. We extended these results to include low-density polymer foams using nonequilibrium MD techniques and found good quantitative agreement with experiment. Here, we have measured the local temperature during void collapse to investigate the formation of hot spots and their relationship to polymer dissociation in foams.

  10. Mutational hot spots in Ig V region genes of human follicular lymphomas

    PubMed Central

    1988-01-01

    The genes coding for the Ig light chains expressed in two cases of human follicular lymphoma were cloned and sequenced. In each case, multiple independent isolates of the tumor population were compared. Although each tumor represented a single clone of B cells with a unique V/J joint, different cells within each tumor had accumulated multiple point mutations in the V gene during clonal expansion. Most of the mutations observed were silent, but some resulted in amino acid replacements. Identical silent mutations were often observed in independent isolates of each tumor. By combining the current data with VH sequences obtained previously from the same cells, it was apparent that the repetitive silent mutations could not be explained solely by a genealogic tree. Such mutations could represent hot spots whose tendency to mutate may be influenced by neighboring DNA sequences or by the methylation of specific cytosine residues. PMID:3045247

  11. From electroconvective vortices to current hot spots on ion selective membranes subject to concentration polarization

    NASA Astrophysics Data System (ADS)

    Wang, Karen; Mani, Ali

    2016-11-01

    Electroconvective instabilities near ion-selective surfaces have been shown to greatly enhance ion transport and play a significant role in a wide range of applications in electrochemistry. When the driving voltage exceeds a threshold, electroconvection becomes chaotic and leads to intermittent spikes of current density on the ion-selective surface. We present an investigation of this phenomenon by considering a canonical setting consisting of a symmetric binary electrolyte next to a flat, ion-selective membrane subject to an external driving voltage. By tracking individual rolls of vortices, we reveal the common mechanism under which the three-way coupled fluid dynamics, ion transport, and electrostatic effects lead to advective displacement of ion concentration field, sustained vortices and vortex migration, and current hot spots on the membrane.

  12. Anatomy of a Venusian hot spot - Geology, gravity, and mantle dynamics of Eistla Regio

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.; Phillips, Roger J.

    1992-01-01

    Results of a study of the western and central portions of the Venusian hot spot Eistla Regio are presented. Magellan radar images were mapped to elucidate the general geologic history of the region. Radial fracture systems both on the rises and volcanoes indicate that uplift and associated faulting accompanied volcanic construction. Prominent fracture zones strike WNW to NW, parallel to the long axis of the highlands. The largest of these, Guor Linea, exhibits a progressive deformation history that may include minor clockwise rotation in addition to bulk NNE-SSW extension. Pioneer Venus line-of-sight accelerations were inverted for vertical gravity which, when combined with topography, were used to solve for mass anomalies on the crust-mantle boundary and in the upper levels of the mantle convective system.

  13. Whole-genome sequencing in autism identifies hot spots for de novo germline mutation.

    PubMed

    Michaelson, Jacob J; Shi, Yujian; Gujral, Madhusudan; Zheng, Hancheng; Malhotra, Dheeraj; Jin, Xin; Jian, Minghan; Liu, Guangming; Greer, Douglas; Bhandari, Abhishek; Wu, Wenting; Corominas, Roser; Peoples, Aine; Koren, Amnon; Gore, Athurva; Kang, Shuli; Lin, Guan Ning; Estabillo, Jasper; Gadomski, Therese; Singh, Balvindar; Zhang, Kun; Akshoomoff, Natacha; Corsello, Christina; McCarroll, Steven; Iakoucheva, Lilia M; Li, Yingrui; Wang, Jun; Sebat, Jonathan

    2012-12-21

    De novo mutation plays an important role in autism spectrum disorders (ASDs). Notably, pathogenic copy number variants (CNVs) are characterized by high mutation rates. We hypothesize that hypermutability is a property of ASD genes and may also include nucleotide-substitution hot spots. We investigated global patterns of germline mutation by whole-genome sequencing of monozygotic twins concordant for ASD and their parents. Mutation rates varied widely throughout the genome (by 100-fold) and could be explained by intrinsic characteristics of DNA sequence and chromatin structure. Dense clusters of mutations within individual genomes were attributable to compound mutation or gene conversion. Hypermutability was a characteristic of genes involved in ASD and other diseases. In addition, genes impacted by mutations in this study were associated with ASD in independent exome-sequencing data sets. Our findings suggest that regional hypermutation is a significant factor shaping patterns of genetic variation and disease risk in humans.

  14. Simulation of the radiation from the hot spot of an X-pinch

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.; Artyomov, A. P.; Chaikovsky, S. A.; Oreshkin, E. V.; Rousskikh, A. G.

    2017-01-01

    The results of X-pinch experiments performed using a small-sized pulse generator are analyzed. The generator, capable of producing a 200-kA, 180-ns current, was loaded with an X-pinch made of four 35-μm-diameter aluminum wires. The analysis consists of a one-dimensional radiation magnetohydrodynamic simulation of the formation of a hot spot in an X-pinch, taking into account the outflow of material from the neck region. The radiation loss and the ion species composition of the pinch plasma are calculated based on a stationary collisional-radiative model, including balance equations for the populations of individual levels. With this model, good agreement between simulation predictions and experimental data has been achieved: the experimental and the calculated radiation power and pulse duration differ by no more than twofold. It has been shown that the x-ray pulse is formed in the radiative collapse region, near its boundary.

  15. Particle accelerators in the hot spots of radio galaxy 3C 445, imaged with the VLT.

    PubMed

    Prieto, M Almudena; Brunetti, Gianfranco; Mack, Karl-Heinz

    2002-10-04

    Hot spots (HSs) are regions of enhanced radio emission produced by supersonic jets at the tip of the radio lobes of powerful radio sources. Obtained with the Very Large Telescope (VLT), images of the HSs in the radio galaxy 3C 445 show bright knots embedded in diffuse optical emission distributed along the post-shock region created by the impact of the jet into the intergalactic medium. The observations reported here confirm that relativistic electrons are accelerated by Fermi-I acceleration processes in HSs. Furthermore, both the diffuse emission tracing the rims of the front shock and the multiple knots demonstrate the presence of additional continuous re-acceleration processes of electrons (Fermi-II).

  16. Shear-strain Sensitivity of Energetic Crystals and the Origin of Hot-spots

    NASA Astrophysics Data System (ADS)

    Kuklja, Maija; Rashkeev, Sergey

    2007-06-01

    Simulation of shear-induced chemical reactions of decomposition of crystalline FOX-7 and TATB is performed by means of Density Functional Theory and First Principles Molecular Dynamics. It is shown that the shear-strain deformation plays a crucial role in defining the sensitivity of explosive crystals to initiation and strongly depends on the shape of crystalline layers constituting the materials. Energetic barriers for FOX-7 decomposition are found to decrease due to shear while those for TATB are not affected by this deformation. We discuss possible mechanisms of chemistry in hot spots, associated with the local shear-strain deformation. This work made possible to provide specific recommendations for synthesis of insensitive energetic materials.

  17. The Role of Water Occlusion for the Definition of a Protein Binding Hot-Spot.

    PubMed

    Moreira, Irina S

    2015-01-01

    Biological systems rely on the establishment of interactions between biomolecules, which take place in the aqueous environment of the cell. It was already demonstrated that a small set of residues at the interface, Hot-Spots(HS), contributes significantly to the binding free energy. However, these energetic determinants of affinity and specificity are still not fully understood. Moreover, the contribution of water to their HS character is also poorly characterized. In this review, we have focused on the structural data available that support the occlusion of HS from solvent, and therefore the "O-ring theory"not only on protein-protein but also on protein-DNA complexes. We also emphasized the use of Solvent Accessible Surface Area (SASA) features in a variety of machine-learning approaches that aim to detect binding HS.

  18. Current hot spot in the spin-valley blockade in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Széchenyi, Gábor; Pályi, András

    2013-12-01

    We present a theoretical study of the spin-valley blockade transport effect in a double quantum dot defined in a straight carbon nanotube. We find that intervalley scattering due to short-range impurities completely lifts the spin-valley blockade and induces a large leakage current in a certain confined range of the external magnetic field vector. This current hot spot emerges due to different effective magnetic fields acting on the spin-valley qubit states of the two quantum dots. Our predictions are compared to a recent measurement [F. Pei , Nat. Nanotech.1748-338710.1038/nnano.2012.160 7, 630 (2012)]. We discuss the implications for blockade-based schemes for qubit initialization/readout and motion sensing of nanotube-based mechanical resonators.

  19. Hot spots in mortality from drug poisoning in the United States, 2007-2009.

    PubMed

    Rossen, Lauren M; Khan, Diba; Warner, Margaret

    2014-03-01

    Over the past several years, the death rate associated with drug poisoning has increased by over 300% in the U.S. Drug poisoning mortality varies widely by state, but geographic variation at the substate level has largely not been explored. National mortality data (2007-2009) and small area estimation methods were used to predict age-adjusted death rates due to drug poisoning at the county level, which were then mapped in order to explore: whether drug poisoning mortality clusters by county, and where hot and cold spots occur (i.e., groups of counties that evidence extremely high or low age-adjusted death rates due to drug poisoning). Results highlight several regions of the U.S. where the burden of drug poisoning mortality is especially high. Findings may help inform efforts to address the growing problem of drug poisoning mortality by indicating where the epidemic is concentrated geographically.

  20. Anatomy of a Venusian hot spot - Geology, gravity, and mantle dynamics of Eistla Regio

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.; Phillips, Roger J.

    1992-01-01

    Results of a study of the western and central portions of the Venusian hot spot Eistla Regio are presented. Magellan radar images were mapped to elucidate the general geologic history of the region. Radial fracture systems both on the rises and volcanoes indicate that uplift and associated faulting accompanied volcanic construction. Prominent fracture zones strike WNW to NW, parallel to the long axis of the highlands. The largest of these, Guor Linea, exhibits a progressive deformation history that may include minor clockwise rotation in addition to bulk NNE-SSW extension. Pioneer Venus line-of-sight accelerations were inverted for vertical gravity which, when combined with topography, were used to solve for mass anomalies on the crust-mantle boundary and in the upper levels of the mantle convective system.

  1. The influences of particle number on hot spots in strongly coupled metal nanoparticles chain

    NASA Astrophysics Data System (ADS)

    Wang, Z. B.; Luk'yanchuk, B. S.; Guo, W.; Edwardson, S. P.; Whitehead, D. J.; Li, L.; Liu, Z.; Watkins, K. G.

    2008-03-01

    In understanding of the hot spot phenomenon in single-molecule surface enhanced Raman scattering (SM-SERS), the electromagnetic field within the gaps of dimers (i.e., two particle systems) has attracted much interest as it provides significant field amplification over single isolated nanoparticles. In addition to the existing understanding of the dimer systems, we show in this paper that field enhancement within the gaps of a particle chain could maximize at a particle number N>2, due to the near-field coupled plasmon resonance of the chain. This particle number effect was theoretically observed for the gold (Au) nanoparticles chain but not for the silver (Ag) chain. We attribute the reason to the different behaviors of the dissipative damping of gold and silver in the visible wavelength range. The reported effect can be utilized to design effective gold substrate for SM-SERS applications.

  2. Treatability studies on F/H Area ``hot spot`` groundwater composite. Revision 1

    SciTech Connect

    Bibler, J.P.

    1993-08-30

    The data found in this report were collected from laboratory experiments that were conducted to characterize the ``hot spot`` groundwater before and after pH adjustment, to describe the settling behavior and particle size of the precipitates resulting from pH adjustment, and to compare several methods of pH adjustment. Although Decontamination Factors (DFs) for all precipitating agents are similar, the best settling characteristics and most manageable precipitate were produced when 25 ppM Al{sup 3+} was introduced as Al{sub 2}(SO{sub 4}){sub 3} and pH adjustment was made from 6--8 with NaOH. The resulting precipitate will not be a hazardous secondary waste.

  3. Integrative Analysis of Hot Spot Conditions in MagLIF Experiments

    NASA Astrophysics Data System (ADS)

    Knapp, Patrick; Gomez, Matthew; Harding, Eric; Hansen, Stephanie; Hahn, Kelly; Geissel, Matthias; Chandler, Gordon; Smith, Ian; Slutz, Steve; Jennings, Chris; Martin, Matthew; Schmit, Paul; Peterson, Kyle; Rochau, Gregory; McBride, Ryan; Sinars, Daniel

    2016-10-01

    A large data set incorporating all available neutron and x-ray data is used to analyze a broad range of Magnetized Liner Inertial Fusion (MagLIF) experiments conducted on the Z machine at Sandia National Laboratories over the past two years. Electron and ion temperatures, electron density, mix fraction, burn volume and duration, and neutron and x-ray yields are all measured on each experiment; several through multiple independent methods. Complementary methods are used to infer the hot spot energy and pressure, and trends are analyzed. The results are placed in the context of accepted performance metrics for Magneto-Inertial Fusion. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE.

  4. Recyclable molecular trapping and SERS detection in silver-loaded agarose gels with dynamic hot spots.

    PubMed

    Aldeanueva-Potel, Paula; Faoucher, Erwan; Alvarez-Puebla, Ramón A; Liz-Marzán, Luis M; Brust, Mathias

    2009-11-15

    We describe the design and fabrication of composite agarose gels, highly loaded with silver nanoparticles. Because the gel can collapse upon drying and recover when rehydrated, it can be foreseen as an excellent mechanical molecular trap that additionally gives rise to dynamic hot spots as the network volume decreases and the silver particles get close to each other, thereby generating the high electromagnetic fields that are needed for ultradetection. Additionally, as silver nanoparticles are physically trapped inside the polymer network, analytes can be washed out by dialysis when immersed in a washing solution, so that recycling can be achieved. Finally, the use of SERS for ultradetection of dichlorodiphenyl-trichloroethane (DDT) is reported for the first time, demonstrating the ability of this novel nanocomposite material to reversibly sequester nonconventional SERS analytes.

  5. Hot spot analysis applied to identify ecosystem services potential in Lithuania

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Depellegrin, Daniel; Misiune, Ieva

    2016-04-01

    Hot spot analysis are very useful to identify areas with similar characteristics. This is important for a sustainable use of the territory, since we can identify areas that need to be protected, or restored. This is a great advantage in terms of land use planning and management, since we can allocate resources, reduce the economical costs and do a better intervention in the landscape. Ecosystem services (ES) are different according land use. Since landscape is very heterogeneous, it is of major importance understand their spatial pattern and where are located the areas that provide better ES and the others that provide less services. The objective of this work is to use hot-spot analysis to identify areas with the most valuable ES in Lithuania. CORINE land-cover (CLC) of 2006 was used as the main spatial information. This classification uses a grid of 100 m resolution and extracted a total of 31 land use types. ES ranking was carried out based on expert knowledge. They were asked to evaluate the ES potential of each different CLC from 0 (no potential) to 5 (very high potential). Hot spot analysis were evaluated using the Getis-ord test, which identifies cluster analysis available in ArcGIS toolbox. This tool identifies areas with significantly high low values and significant high values at a p level of 0.05. In this work we used hot spot analysis to assess the distribution of providing, regulating cultural and total (sum of the previous 3) ES. The Z value calculated from Getis-ord was used to statistical analysis to access the clusters of providing, regulating cultural and total ES. ES with high Z value show that they have a high number of cluster areas with high potential of ES. The results showed that the Z-score was significantly different among services (Kruskal Wallis ANOVA =834. 607, p<0.001). The Z score of providing services (0.096±2.239) were significantly higher than the total (0.093±2.045), cultural (0.080±1.979) and regulating (0.076±1.961). These

  6. Enhancement of electron hot spot relaxation in photoexcited plasmonic structures by thermal diffusion

    NASA Astrophysics Data System (ADS)

    Spitzer, F.; Glavin, B. A.; Belotelov, V. I.; Vondran, J.; Akimov, I. A.; Kasture, S.; Achanta, V. G.; Yakovlev, D. R.; Bayer, M.

    2016-11-01

    We demonstrate that in confined plasmonic metal structures subject to ultrafast laser excitation, electron thermal diffusion (ETD) can provide spatial redistribution of excess energy faster than its transfer to the lattice. This relaxation occurs after the excitation of nanometer-sized hot spots in the confined structure, changing sensitively the optical parameters in these regions. The changes become essential when the plasmonic resonance condition is met for both excitation and detection, as evidenced by a pump-probe experiment on plasmonic gold lattices: Subpicosecond relaxation with characteristic times well described by a two-temperature model involving ETD is observed. The results suggest that the dynamical optical response in plasmonic structures can be tuned by the selection of the structural geometry as well as the choice of wavelength and polarization of the excitation and detection light.

  7. Rett syndrome in females with CTS hot spot deletions: a disorder profile.

    PubMed

    Smeets, E; Terhal, P; Casaer, P; Peters, A; Midro, A; Schollen, E; van Roozendaal, K; Moog, U; Matthijs, G; Herbergs, J; Smeets, H; Curfs, L; Schrander-Stumpel, C; Fryns, J P

    2005-01-15

    From a series of 107 females with Rett syndrome (RTT), we describe the long-term history of ten females with a deletion in the C-terminus of the MECP2 gene. We observed that their disorder profile is clinically recognizable with time and different from other atypical and milder RTT phenotypes. In females with hot spot deletions in the C-terminus, dystonia is present from childhood and results in a serious spine deformation in spite of preventive measures. Their adaptive behavior is surprisingly better preserved and in contrast with the typical decline in motor functioning. The delineation of disorder profiles by long-term clinical observation can teach us about genotype/phenotype relationships and eventually about the effect of epigenetic phenomena on the final phenotype.

  8. VLBI OBSERVATIONS OF 10 COMPACT SYMMETRIC OBJECT CANDIDATES: EXPANSION VELOCITIES OF HOT SPOTS

    SciTech Connect

    An Tao; Wu Fang; Hong Xiaoyu; Wang Weihua; Chen Xi; Yang Jun; Taylor, Gregory B.; Baan, Willem A.; Liu Xiang; Wang Min; Hao Longfei; Cui Lang E-mail: an@astron.nl

    2012-01-01

    Observations of 10 Compact Symmetric Object (CSO) candidates have been made with the Very Long Baseline Array (VLBA) at 8.4 GHz in 2005 and with a combined Chinese and European Very Long Baseline Interferometry (VLBI) array at 8.4 GHz in 2009. The 2009 observations incorporate for the first time the two new Chinese telescopes at Miyun and Kunming for international astrophysical observations. The observational data, in combination with archival VLBA data from previous epochs, have been used to derive the proper motions of the VLBI components. Because of the long time baseline of {approx}16 years of the VLBI data sets, the expansion velocities of the hot spots can be measured at an accuracy as high as {approx}1.3 {mu}as yr{sup -1}. Six of the ten sources are identified as CSOs with a typical double or triple morphology on the basis of both spectral index maps and their mirror symmetry of proper motions of the terminal hot spots. The compact double source J1324+4048 is also identified as a CSO candidate. Among the three remaining sources, J1756+5748 and J2312+3847 are identified as core-jet sources with proper motions of their jet components relating to systemic source expansion. The third source J0017+5312 is likely also a core-jet source, but a robust detection of a core is needed for an unambiguous identification. The kinematic ages of the CSOs derived from proper motions range from 300 to 2500 years. The kinematic age distribution of the CSOs confirm an overabundance of compact young CSOs with ages less than 500 years. CSOs with known kinematic ages may be used to study the dynamical evolution of extragalactic radio sources at early stages.

  9. Causes of hot-spot wetland loss in the Mississippi delta plain

    USGS Publications Warehouse

    Morton, R.A.; Tiling, G.; Ferina, N.F.

    2003-01-01

    Field surveys and sediment cores were used to estimate marsh erosion and land subsidence at Madison Bay, a well-known wetland loss hot spot in coastal Louisiana. Former marshes of Madison Bay are under about 1 m of water. Nearly two-thirds of the permanent flooding was caused by rapid subsidence in the late 1960s, whereas the other third was caused by subsequent erosion. Subsidence rates near Madison Bay since the 1960s (???20 mm/yr) are an order of magnitude greater than deltaic subsidence rates averaged for the past 400-4000 yr (???2 mm/yr). The rapid acceleration and unexpected decline in wetland losses in the Mississippi delta plain are difficult to explain on the basis of most physical and biogeochemical processes. There are, however, close temporal and spatial correlations among regional wetland loss, high subsidence rates, and large-volume fluid production from nearby hydrocarbon fields. The decreased rates of wetland loss since the 1970s may be related to decreased rates of subsidence caused by significantly decreased rates of subsurface fluid withdrawal. Annual fluid production from the Lapeyrouse, Lirette, and Bay Baptiste fields that encompass Madison Bay accelerated in the 1960s, peaked about 1970, and then declined abruptly. Large decreases in pore pressure in the Lapeyrouse field have likely altered subsurface stresses and reactivated a major fault that coincides with the wetland loss hot spot. Therefore, wetland losses at Madison Bay can be closely linked to rapid subsidence and possible fault reactivation induced by long-term, large-volume hydrocarbon production. ?? 2003. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  10. Cooling off health security hot spots: getting on top of it down under.

    PubMed

    Murray, Kris A; Skerratt, Lee F; Speare, Rick; Ritchie, Scott; Smout, Felicity; Hedlefs, Robert; Lee, Jonathan

    2012-11-01

    Australia is free of many diseases, pests and weeds found elsewhere in the world due to its geographical isolation and relatively good health security practices. However, its health security is under increasing pressure due to a number of ecological, climatic, demographic and behavioural changes occurring globally. North Queensland is a high risk area (a health security hot spot) for Australia, due in part to its connection to neighbouring countries via the Torres Strait and the Indo-Papuan conduit, its high diversity of wildlife reservoirs and its environmental characteristics. Major outbreaks of exotic diseases, pests and weeds in Australia can cost in excess of $1 billion; however, most expenditure on health security is reactive apart from preventive measures undertaken for a few high profile diseases, pests and weeds. Large gains in health security could therefore be made by spending more on pre-emptive approaches to reduce the risk of outbreaks, invasion/spread and establishment, despite these gains being difficult to quantify. Although biosecurity threats may initially have regional impacts (e.g. Hendra virus), a break down in security in health security hot spots can have national and international consequences, as has been seen recently in other regions with the emergence of SARS and pandemic avian influenza. Novel approaches should be driven by building research and management capacity, particularly in the regions where threats arise, a model that is applicable both in Australia and in other regions of the world that value and therefore aim to improve their strategies for maintaining health security. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Bioavailable dissolved organic matter and biological hot spots during austral winter in Antarctic waters

    NASA Astrophysics Data System (ADS)

    Shen, Yuan; Benner, Ronald; Murray, Alison E.; Gimpel, Carla; Greg Mitchell, B.; Weiss, Elliot L.; Reiss, Christian

    2017-01-01

    Primary production and heterotrophic bacterial activity in the Antarctic Ocean are generally low during the austral winter. Organic carbon is considered to be a major factor limiting bacterial metabolism, but few studies have investigated the bioavailability of organic matter during winter. Herein, the chemical composition and bioavailability of dissolved organic matter (DOM) were investigated in surface (5-100 m) and mesopelagic (200-750 m) waters off the northwestern Antarctic Peninsula during August 2012. Concentrations of dissolved organic carbon (DOC) were low (42 ± 4 µmol L-1) and showed no apparent spatial patterns. By contrast, the composition of DOM exhibited significant spatial trends that reflected varying ecosystem productivity and water masses. Surface distributions of chlorophyll-a and particulate organic carbon depicted a southward decline in primary productivity from open waters (60.0°S-61.5°S) to ice-covered regions (61.5°S-62.5°S). This trend was evident from concentrations and DOC-normalized yields of dissolved amino acids in the surface waters, indicating decreasing DOM bioavailability with increasing latitude. A different pattern of DOM bioavailability was observed in the mesopelagic water masses, where amino acids indicated highly altered DOM in the Circumpolar Deep Water and bioavailable DOM in the Transitional Weddell Water. Depth distributions of amino acid yields and compositions revealed hot spots of elevated bioavailable DOM at ˜75 m relative to surrounding waters at most ice-free stations. Relatively low mole percentages of bacterially derived D-amino acids in hot spots were consistent with an algal source of bioavailable DOM. Overall, these results reveal the occurrence and spatial heterogeneity of bioavailable substrates in Antarctic waters during winter.

  12. Is the Juan Fernandez Ridge (nazca Plate) a Deep-Mantle Hot SPOT Trail?

    NASA Astrophysics Data System (ADS)

    Lara, L. E.; Selles, D.; Díaz, A.; Piña-Gauthier, M.

    2011-12-01

    The Juan Fernández Ridge on the oceanic Nazca plate is thought to be a classic hot spot trail because of the apparent westward rejuvenation of the eruptive ages. Geochronological data is still scarce to prove this is the case, and other hypothesis should be taken into account. There are a few constrains, like the ca. 9 Ma Ar-Ar age of the O'Higgins seamount (115 km from the Chile-Perú trench), published K-Ar ages of ca. 3-4 Ma in Robinson Crusoe island (580 km from the trench) and ca. 1 Ma in Alejandro Selkirk (180 km further west). New reconnaissance K-Ar ages in Robinson Crusoe yield ca. 1-3 Ma, which partially overlap with the age of Alejandro Selkirk, breaking the expected age progression given that the Nazca plate moves eastwards at ca. 6-8 cm/yr. New geological mapping also shows a sharp unconformity between the older, strongly altered sequences and more recent, post-erosional volcanic piles, where only the vent facies have disappeared. A fixed deep-mantle plume origin for Pacific hot spots has been widely debated and concurrent phenomena arose as a possible explanation for non-linear age progressions and/or long-lived volcanic activity. In fact, intraplate regional tectonics, plume displacement, and mantle heterogeneities could be the main factor of the ridge architecture or the mask for a first-order linear trend. An ongoing mapping and dating effort is aimed to understand the evolution of the Juan Fernández Ridge, testing the main hypothesis. Fondecyt grant 110966 is acknowledged for financial support.

  13. Nuclear Star Formation in the Hot-Spot Galaxy NGC 2903

    NASA Technical Reports Server (NTRS)

    Alonso-Herrero, A.; Ryder, S. D.; Knapen, J. H.

    1994-01-01

    We present high-resolution near-infrared imaging obtained using adaptive optics and HST/NICMOS and ground-based spectroscopy of the hot-spot galaxy NGC 2903. Our near-infrared resolution imaging enables us to resolve the infrared hot spots into individual young stellar clusters or groups of these. The spatial distribution of the stellar clusters is not coincident with that of the bright H II regions, as revealed by the HST/NICMOS Pace image. Overall, the circumnuclear star formation in NGC 2903 shows a ring-like morphology with an approximate diameter of 625 pc. The SF properties of the stellar clusters and H II regions have been studied using the photometric and spectroscopic information in conjunction with evolutionary synthesis models. The population of bright stellar clusters shows a very narrow range of ages, 4 to 7 x 10(exp 6) yr after the peak of star formation, or absolute ages 6.5 to 9.5 x 10(exp 6) yr (for the assumed short-duration Gaussian bursts), and luminosities similar to the clusters found in the Antennae interacting galaxy. This population of young stellar clusters accounts for some 7 - 12% of the total stellar mass in the central 625 pc of NGC 2903. The H II regions in the ring of star formation have luminosities close to that of the super-giant H II region 30 Doradus, they are younger than the stellar clusters, and will probably evolve into bright infrared stellar clusters similar to those observed today. We find that the star formation efficiency in the central regions of NGC 2903 is higher than in normal galaxies, approaching the lower end of infrared luminous galaxies.

  14. Wafer hot spot identification through advanced photomask characterization techniques: part 2

    NASA Astrophysics Data System (ADS)

    Choi, Yohan; Green, Michael; Cho, Young; Ham, Young; Lin, Howard; Lan, Andy; Yang, Richer; Lung, Mike

    2017-03-01

    Historically, 1D metrics such as Mean to Target (MTT) and CD Uniformity (CDU) have been adequate for mask end users to evaluate and predict the mask impact on the wafer process. However, the wafer lithographer's process margin is shrinking at advanced nodes to a point that classical mask CD metrics are no longer adequate to gauge the mask contribution to wafer process error. For example, wafer CDU error at advanced nodes is impacted by mask factors such as 3-dimensional (3D) effects and mask pattern fidelity on sub-resolution assist features (SRAFs) used in Optical Proximity Correction (OPC) models of ever-increasing complexity. To overcome the limitation of 1D metrics, there are numerous on-going industry efforts to better define wafer-predictive metrics through both standard mask metrology and aerial CD methods. Even with these improvements, the industry continues to struggle to define useful correlative metrics that link the mask to final device performance. In part 1 of this work, we utilized advanced mask pattern characterization techniques to extract potential hot spots on the mask and link them, theoretically, to issues with final wafer performance. In this paper, part 2, we complete the work by verifying these techniques at wafer level. The test vehicle (TV) that was used for hot spot detection on the mask in part 1 will be used to expose wafers. The results will be used to verify the mask-level predictions. Finally, wafer performance with predicted and verified mask/wafer condition will be shown as the result of advanced mask characterization. The goal is to maximize mask end user yield through mask-wafer technology harmonization. This harmonization will provide the necessary feedback to determine optimum design, mask specifications, and mask-making conditions for optimal wafer process margin.

  15. Coherent Terahertz Emission of Intrinsic Josephson Junction Stacks in the Hot Spot Regime

    NASA Astrophysics Data System (ADS)

    Kleiner, Reinhold

    2011-03-01

    Having small sized active and tunable devices operating at frequencies up to the Terahertz (THz) range is one of the goals of modern electronics. However, there is still a lack of good active or passive devices, often referred to as the ``Terahertz gap.'' Intrinsic Josephson junctions formed by the layered crystal structure of high temperature superconductors such as Bi 2 Sr 2 CaCu 2 O8 have the potential to operate in this regime. While for a long time the research on THz generation with this type of junctions was carried out with perhaps only modest success, recently synchronous emission, with an estimated output power in the μ W range, of stacks consisting of several hundred intrinsic Josephson junctions was achieved. We report on the investigation of THz electromagnetic wave generation in intrinsic junction stacks (mesas) of different geometries, using a combination of transport measurement, direct electromagnetic wave detection and Low Temperature Scanning Laser Microscopy [2,3]. At high enough input power a hot spot (a region heated to above the superconducting transition temperature) coexists with regions being still in the superconducting state. In the ``cold'' regions cavity resonances can occur, synchronizing the ac Josephson currents and giving rise to strong and stable coherent THz emission. We discuss possible scenarios of the hot spot/wave interaction and its relation to the generation of coherent THz radiation. In collaboration with S. Guenon, B. Gross, M. Gruenzweig, D. Koelle, H. B. Wang, J. Yuan, A. Iishi, T. Hatano, Z. Jiang, Y. Zhong, P.H. Wu.

  16. Downscaling Future Changes of the Global Warming Hot Spots in the Western Boundary Current Systems

    NASA Astrophysics Data System (ADS)

    Zhang, X.

    2016-02-01

    Ocean warming most obvious in the upper 200-300 m due to extra heat being absorbed is an important manifestation of anthropogenic climate change. Global mean sea surface temperature (SST) warming is projected to be between 0.8 and 3.1 oC over 2081-2100 relative to 1986-2005, as reported in the Fifth Assessment Report of IPCC based on Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models. However, SST changes are not expected to be geographically uniform, and there are several hot spots with much faster warming than the global mean, especially in the western boundary currents (WBCs) and their extension regions. However, with coarse resolution ( 1o in the ocean component), CMIP5 climate models cannot resolve these WBCs and their eddy field very well. Here we use a near-global eddy-resolving (0.1o resolution) ocean general circulation model (OGCM) to downscale future climate changes over the 21st century, by applying atmospheric anomaly fields derived from the ensemble mean of 17 CMIP5 models under the Representative Concentration Pathway 8.5. Localized strong upper ocean warming ( 5 oC), not only in the surface layer but often extending down to several hundred of meters, can be found in all WBCs and their extensions (namely, Kuroshio, Gulf Stream, Agulhas Current, East Australian Current and Brazil Current). Through examining changes of ocean fields (velocity, temperature and salinity), mean and eddy kinetic energy and upper ocean heat budget, we study those warming hot spots in detail and find that they can be explained to the first order by the poleward expansion and/or intensification of subtropical ocean gyres. With embedded biogeochemical fields in the OGCM, we further investigate how the WBCs and associated eddy activity changes affect nutrient supply, biogeochemical response and primary productivity.

  17. Juno-JIRAM: Overview of Preliminary Results in the Study of Jupiter Hot-Spots

    NASA Astrophysics Data System (ADS)

    Adriani, A.; Grassi, D.; Sindoni, G.; Mura, A.; Noschese, R.; Cicchetti, A.; Altieri, F.; Dinelli, B. M.; Moriconi, M. L.; Fabiano, F.; Migliorini, A.; Filacchione, G.; Tosi, F.; Piccioni, G.; Turrini, D.; Bolton, S. J.; Levin, S.; Connerney, J. E. P.; Olivieri, A.

    2016-12-01

    The JIRAM instrument on board of the Juno spacecraft includes a spectrometer channel that operates in the range 2-5 μm with a spectral resolution of about 14 nm.Data from this channel are particularly valuable in the study of the hot-spots, regions of the Jupiter atmosphere where the upper cloud decks are relatively thin and the thermal radiation emitted at pressures down to 3-4 bars can be measured by infrared remote-sensing instruments. Previous studies on NIMS-Galileo [1] and VIMS-Cassini [2] data, as well as a specific assessment for the JIRAM instrument [3], have demonstrated the possibility to constraints the content of H2O, NH3 and PH3 from moderate-resolution spectra of hot spots covering the CH4 transparency window at 5 μm.This talk reviews the first results on the retrieval of these species from the JIRAM observations acquired around the first Juno pericenter after the orbit insertion. The specific characteristics of the orbit have made possible a fairly complete latitudinal and longitudinal coverage of the thermal emissions at low emission angles over large portions of the Jupiter disk. Maps of gas content are compared against the previous results derived from NIMS, VIMS and ISO spectra.[1] Irwin et al., 1998, doi:10.1029/98JE00948[2] Giles et al., 2015, doi:10.1016/j.icarus.2015.05.030[3] Grassi et al., 2010, doi:10.1016/j.pss.2010.05.003

  18. Identification of interacting hot spots in the beta3 integrin stalk using comprehensive interface design.

    PubMed

    Donald, Jason E; Zhu, Hua; Litvinov, Rustem I; DeGrado, William F; Bennett, Joel S

    2010-12-03

    Protein-protein interfaces are usually large and complementary surfaces, but specific side chains, representing energetic "hot spots," often contribute disproportionately to binding free energy. We used a computational method, comprehensive interface design, to identify hot spots in the interface between the stalk regions of the β3 and the complementary αIIb and αv integrin subunits. Using the Rosetta alanine-scanning and design algorithms to predict destabilizing, stabilizing, and neutral mutations in the β3 region extending from residues Lys(532) through Gly(690), we predicted eight alanine mutations that would destabilize the αIIbβ3 interface as well as nine predicted to destabilize the αvβ3 interface, by at least 0.3 kcal/mol. The mutations were widely and unevenly distributed, with four between residues 552 and 563 and five between 590 and 610, but none between 565 and 589, and 611 and 655. Further, mutations destabilizing the αvβ3 and αIIbβ3 interfaces were not identical. The predictions were then tested by introducing selected mutations into the full-length integrins expressed in Chinese hamster ovary cells. Five mutations predicted to destabilize αIIb and β3 caused fibrinogen binding to αIIbβ3, whereas three of four predicted to be neutral or stabilizing did not. Conversely, a mutation predicted to destabilize αvβ3, but not αIIbβ3 (D552A), caused osteopontin binding to αvβ3, but not fibrinogen binding to αIIbβ3. These results indicate that stability of the distal stalk interface is involved in constraining integrins in stable, inactive conformations. Further, they demonstrate the ability of comprehensive interface design to identify functionally significant integrin mutations.

  19. Probing the Hawaiian Hot Spot With New Broadband Ocean Bottom Instruments

    NASA Astrophysics Data System (ADS)

    Laske, Gabi; Collins, John A.; Wolfe, Cecily J.; Solomon, Sean C.; Detrick, Robert S.; Orcutt, John A.; Bercovici, David; Hauri, Erik H.

    2009-10-01

    The Hawaiian hot spot is regarded as the textbook example of the product of a deep-rooted mantle plume [Wilson, 1963; Morgan, 1971]. Its isolated location, far from any plate boundary, should provide an opportunity to test most basic hypotheses on the nature of plume-plate interaction and related magmatism [e.g., Ribe and Christensen, 1999]. Yet the lack of crucial geophysical data has sustained a debate about whether Hawaii's volcanism is plume-related or is instead the consequence of more shallow processes, such as the progressive fracturing of the plate in response to extensional stresses [Turcotte and Oxburgh, 1973]. In the plume model for Hawaii's volcanism, hot material is expected to ascend near vertically within the more viscous surrounding mantle before ponding and spreading laterally beneath the rigid lithosphere. Mantle convection in general, and the fast moving Pacific plate in particular, shear and tilt the rising plume. The plume top is dragged downstream by the plate, and this dragged material may give rise to an elongated bathymetric swell [Davies, 1988; Olson, 1990; Sleep, 1990; Phipps Morgan et al., 1995]. However, identifying the dominant cause of the swell remains elusive, and proposed mechanisms include thermal rejuvenation, dynamic support, compositional buoyancy, and mechanical erosion (see Li et al. [2004] for a summary). There is also considerable debate about the continuity of the plume within the mantle, how discrete islands are formed, and how a deep-rooted plume interacts with the mantle transition zone [e.g., van Keken and Gable, 1995].

  20. Nanopatterning and Hot Spot Modeling of YBCO Ultrathin Film Constrictions for THz Mixers

    NASA Astrophysics Data System (ADS)

    Ladret, Romain G.; Degardin, Annick F.; Kreisler, Alain J.

    2013-06-01

    High-TC hot electron bolometers (HEB) are promising THz mixers due to their expected wide bandwidth, large mixing gain, and low intrinsic noise. To achieve this goal, 0.6-μm-size constrictions were patterned on YBaCuO-based, 10-40-nm-thick films grown on (100) MgO substrates, which as previously reported, exhibited good DC superconducting properties. In this paper, we have simulated the DC and mixer characteristics of YBaCuO HEBs with a hot spot model usually dedicated to low-TC devices. For a 100 nm × 100 nm × 10 nm constriction, the expected double sideband noise temperature TN is 2000 K for 5 μW local oscillator (LO) power (G = -13.5 dB conversion gain). For a larger (but more realistic according to YBaCuO aging effects) 600 nm × 1000 nm × 35 nm constriction, TN = 1300 K at 200 μW LO power (G = -12 dB). This approach is expected to allow optimizing the operation of the HEB constriction coupled to a THz planar antenna.

  1. High Resolution Spectroscopy of the GRS and NEB Hot Spots of Jupiter Following Galileo Observations

    NASA Astrophysics Data System (ADS)

    Drossart, P.; Maillard, J.-P.; Bezard, B.; Roos-Serote, M.; Lellouch, E.; Encrenaz, Th.

    1996-09-01

    High resolution spectra of Jupiter at 5 mu m (resolving power of 10,000) have been obtained with the Fourier Transform Spectrometer at Canada-France-Hawaii Telescope during the nights of July 29--31, 1996. The following regions have been observed with a 2.5-arcsec aperture: the Great Red Spot and vicinity, three different 5-mu m hot spots of the North Equatorial Belt at 6.5deg N, and the Northern latitudes at 60deg N. The GRS and one of the hot spots were the targets of the Galileo/NIMS observations in the first orbit (Carlson et al., DPS-96), and the combination of the NIMS high spatial resolution spectral images with the FTS high spectral resolution observations will give important constraints on the tropospheric structure and composition of Jupiter. The 5-mu m spectrum of Jupiter is sensitive to the deep (2--8 bars) atmospheric structure, in particular to an intermediate cloud located between 1.5 and 2 bars, (Drossart et al., Icarus, 1982), probably the cloud observed by the Galileo Probe nephelometer at 1.55 bar (Ragent et al., Science, 1996). The domain from 4.59 to 4.81 mu m which has been covered, includes the spectral tropospheric absorption features of GeH_4, PH_3, AsH_3 and CH_3D. The atmospheric and cloud structures are both affecting the shape of the spectrum, and these observations give some constraints on the structure of the atmosphere in the observed atmospheric features. In the Northern latitudes, the absorption by AsH_3 is stongly enhanced, more than can be accounted for by emission angle dependence, which suggests an enhancement of AsH_3 in the high latitudes. A similar enhancement in phosphine had been observed in the Northern latitudes (Drossart et al., Icarus, 1990). Such variations could be due to deep convection latitudinal variability, or to a lower photochemical destruction of these compounds at high latitudes. (*) Visiting Astronomer at the Canada-France-Hawaii Telescope, which is operated by the Canadian National Research Council, the

  2. 40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Procedures for determining localized CO... Transit Laws § 93.123 Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis). (a) CO hot-spot analysis. (1) The demonstrations required by § 93.116 (“Localized CO, PM10,...

  3. Searching for biogeochemical hot spots in three dimensions: soil C and N cycling in hydropedologic settings in a northern hardwood forest

    Treesearch

    J.L. Morse; S.F. Werner; C.P. Gillin; C.L. Goodale; S.W. Bailey; K.J. McGuire; P.M. Groffman

    2014-01-01

    Understanding and predicting the extent, location, and function of biogeochemical hot spots at the watershed scale is a frontier in environmental science. We applied a hydropedologic approach to identify (1) biogeochemical differences among morphologically distinct hydropedologic settings and (2) hot spots of microbial carbon (C) and nitrogen (N) cycling activity in a...

  4. Measurement of the hot spot electron temperature in NIF ICF implosions using Krypton x-ray emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, T.; Chen, H.; Patel, P. K.; Schneider, M.; Barrios, M.; Berzak Hopkins, L.; Casey, D.; Chung, H.-K.; Hammel, B.; Jarrott, C.; Nora, R.; Pak, A.; Scott, H.; Spears, B.; Weber, C.

    2015-11-01

    The inference of ion temperature from neutron spectral measurements in indirect-drive ICF implosions is known to be sensitive to non-thermal velocity distributions in the fuel. The electron temperature (Te) inferred from dopant line ratios should not be sensitive to these bulk motions and hence may be a better measure of the thermal temperature of the hot spot. Here we describe a series of experiments to be conducted on the NIF where a small concentration of a mid-Z dopant (Krypton) is added to the fuel gas. The x-ray spectra is measured and the electron temperature is inferred from Kr line ratios. We also quantify the level of radiative cooling in the hot spot due to this mid-Z dopant. These experiments represent the first direct measurement of hot spot Te using spectroscopy, and we will describe the considerations for applying x-ray spectroscopy in such dense and non-uniform hot spots. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. The Cobb hot spot: HIMU-DMM mixing and melting controlled by a progressively thinning lithospheric lid

    NASA Astrophysics Data System (ADS)

    Chadwick, John; Keller, Randall; Kamenov, George; Yogodzinski, Gene; Lupton, John

    2014-08-01

    Cobb Seamount Chain in the northeast Pacific basin records the composition of the Cobb hot spot for the past 33 Myr, as the migrating Juan de Fuca Ridge approached and ultimately overran it ca. 0.5 Myr ago. In this first comprehensive geochemical study of the Cobb chain, major and trace element compositions and Sr, Nd, Pb, and Hf isotopic ratios were measured for whole-rock samples from throughout the chain, and He isotopes were acquired for olivine phenocrysts from one seamount. Trace element modeling indicates increased melting along the chain over time, with progressively more depleted lavas as the ridge approached the hot spot. The isotopic data reveal the first evidence of the high µ (µ = 238U/204Pb) (HIMU) mantle component in the north Pacific basin and are consistent with a progressively decreasing mixing proportion of HIMU melts relative to those from depleted mid-ocean ridge basalt mantle (DMM) in the chain over time. Decreasing lithospheric thickness over the Cobb hot spot due to the approach of the migrating Juan de Fuca ridge allowed adiabatic melting to continue to shallower depths, leading to increased melt fractions of the refractory DMM component in the hot spot and more depleted and MORB-like lavas in the younger Cobb seamounts.

  6. INVESTIGATION OF "HOT-SPOTS" AS A FUNCTION OF MATERIAL REMOVAL IN A LARGE-GRAIN NIOBIUM CAVITY

    SciTech Connect

    Gianluigi Ciovati; Peter Kneisel

    2006-08-21

    Poster - The performance of a single-cell cavity made of RRR > 200 large-grain niobium has been investigated as a function of material removal by buffered chemical polishing. Temperature maps of the cavity surface at 1.7 and 2.0 K were taken for each step of chemical etching and revealed several 'hot-spots', which contribute to the degradation of the cavity quality factor as a function of the RF surface field, mostly at high field levels. It was found that the number of 'hot-spots' decreased for larger material removal. Interestingly, the losses of the 'hot-spots' at different locations evolved differently for successive material removal. The cavity achieved peak surface magnetic fields of about of 130 mT and was limited mostly by thermal quench. By measuring the temperature dependence of the surface resistance at low field between 4.2 K and 1.7 K, the variation of niobium material parameters as a function of material removal could also be investigated. This contribution shows the results of the RF tests along with the temperature maps and the analysis of the losses caused by the 'hot-spots'.

  7. Proposed NIF Experiments to Explore Convergence Ratio and Robustness of Hot Spot Formation in DT Liquid Layer HDC Capsules

    NASA Astrophysics Data System (ADS)

    Olson, R.; Leeper, R.; Grim, G.; Kline, J.; Peterson, R.; Berzak Hopkins, L.; Hamza, A.; Ho, D.; Jones, O.; Lepape, S.; MacKinnon, A.; Meezan, N.; Robey, H.

    2014-10-01

    DT Liquid Layer ICF capsules allow for flexibility in hot spot convergence ratio via the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. High Density Carbon (HDC) is a leading candidate as an ablator material for ICF capsules, and a technique has been developed for lining the inner surface of a HDC shell with an ultra-low-density hydrocarbon foam that will survive wetting with liquid hydrogen. In this presentation, we propose a series of NIF experiments using liquid DT layer (wetted foam) HDC capsules to test the hypothesis that our predictive capability of hot spot formation is robust for a relatively low convergence ratio hot spot, but will become more difficult as vapor pressure is reduced and hot spot convergence ratio is increased. The proposed liquid DT layer HDC capsule ``sub-scale'' experiments utilize near-vacuum hohlraums with NIF laser pulse energies of about 1 MJ, but larger scale experiments are also considered. This work was performed under the auspices of the U. S. DOE by LANL under Contract DE-AC52-06NA25396, and by LLNL under Contract DE-AC52-07NA27344.

  8. Hot Environment Assessment Tool (HEAT) User’s Guide for Apple Mobile Devices

    DTIC Science & Technology

    2015-07-01

    ARL-TR-7347 ● JULY 2015 US Army Research Laboratory Hot Environment Assessment Tool (HEAT) User’s Guide for Apple Mobile...longer needed. Do not return it to the originator. ARL-TR-7347 ● JULY 2015 US Army Research Laboratory Hot Environment Assessment...4. TITLE AND SUBTITLE Hot Environment Assessment Tool (HEAT) User’s Guide for Apple Mobile Devices 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  9. Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

    NASA Astrophysics Data System (ADS)

    Springer, H. K.; Tarver, C. M.; Bastea, S.

    2017-01-01

    The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

  10. Hot spot formation of chloroform in forest soils caused pollution of groundwater

    NASA Astrophysics Data System (ADS)

    Jacobsen, Ole S.; Albers, Christian N.; Laier, Troels; Hunkeler, Daniel

    2015-04-01

    High concentration of chloroform in groundwater is usually attributed to anthropogenic input, but we have found that the groundwater beneath some pristine areas contained chloroform from 1 - 10 µg/L. Groundwater containing chloroform that exceeds 1 µg/L could not be used for drinking water according to Danish regulations. The strict demands on groundwater quality may have to be taken into account when decisions are made regarding the change of land use in order to protect major recharge areas from pollution with nitrate and pesticides resulting from high-yield agriculture production. The terrestrial environment and especially hot spots in forest soils seem to be important contributors to apparent pollution of groundwater with chloroform. We performed a field study to investigate concentration and fluxes of chloroform to the groundwater from in four coniferous forests in order to increase knowledge on the hot spot formation and fate of natural chloroform. We investigated four stations over a period of several years in order to measure the net-formation of chloroform. Field measurements soil air concentrations of chloroform were monitored in five soil profiles down to the groundwater table. Meteorological data were recorded at all stations In the hotspots up to 120 ppbv was found in soil air under the spruce forest, to be compared to an ambient atmospheric concentration of 0.02 ppbv. The concentration of chloroform in soil air showed seasonal variation with a maximum in August-September. The chloroform concentration decreased with depth in all profiles during the summer half-year to about 20 % of concentration in the production layer. However, the concentration is still high enough to give an equilibrium concentration in the upper groundwater of 1-10 µg/L. Stable carbon isotopic analyses of chloroform from the uppermost groundwater in different parts of the forests and from soil water showed values from δ13C = -13 ‰ to -27 ‰, corresponding to the ratio in

  11. Investigation of sources of atmospheric aerosol at a hot spot area in Dhaka, Bangladesh.

    PubMed

    Begum, Bilkis A; Biswas, Swapan K; Kim, Eugene; Hopke, Philip K; Khaliquzzaman, Mohammed

    2005-02-01

    Samples of fine and coarse fractions of airborne particulate matter were collected at the Farm Gate area in Dhaka from July 2001 to March 2002. Dhaka is a hot spot area with very high pollutant concentrations because of the proximity of major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0- to 2.2-microm and 2.2- to 10-microm sizes. The samples were analyzed for elemental concentrations by particle-induced X-ray excitation (PIXE) and for black carbon by reflectivity methods, respectively. The data were analyzed by positive matrix factorization (PMF) to identify the possible sources of atmospheric aerosols in this area. Six sources were found for both the coarse and fine PM fractions. The data sets were also analyzed by an expanded model to explore additional sources. Seven and six factors were obtained for coarse and fine PM fractions, respectively, in these analyses. The identified sources are motor vehicle, soil dust, emissions from construction activities, sea salt, biomass burning/brick kiln, resuspended/fugitive Pb, and two-stroke engines. From the expanded modeling, approximately 50% of the total PM2.2 mass can be attributed to motor vehicles, including two-stroke engine vehicle in this hot spot in Dhaka, whereas the PMF modeling indicates that 45% of the total PM2.2 mass is from motor vehicles. The PMF2 and expanded models could resolve approximately 4% and 3% of the total PM2.2 mass as resuspended/fugitive Pb, respectively. Although, Pb has been eliminated from gasoline in Bangladesh since July 1999, there still may be substantial amounts of accumulated lead in the dust near roadways as well as fugitive Pb emissions from battery reclaimation and other industries. Soil dust is the largest component of the coarse particle fraction (PM2.2-10) accounting for approximately 71% of the total PM2.2-10 mass in the expanded model, whereas from the PMF modeling, the dust (undifferentiated) contribution is approximately 49%.

  12. Spin-up and hot spots can drive mass out of a binary

    NASA Astrophysics Data System (ADS)

    van Rensbergen, W.; De Greve, J. P.; De Loore, C.; Mennekens, N.

    2008-09-01

    Context: The observed distribution of orbital periods of Algols with a B-type primary at birth agrees fairly well with the prediction from conservative theory. Conservative evolution fails, however, to produce the rather large fraction of Algols observed with a high mass-ratio, especially: q in [0.4-0.6]. Aims: In order to keep Algols for a longer time with a higher mass-ratio without disturbing the distribution of orbital periods too much, interacting binaries have to lose a significant fraction of their total mass without losing much angular momentum before or during Algolism. We propose a mechanism that meets both requirements. Methods: In the case of direct impact the gainer spins up: sometimes up to critical velocity. Equatorial material on the gainer is therefore less bound. A similar statement applies to material located at the edge of an accretion disc. The incoming material moreover creates a hot spot in the area of impact. The sum of the rotational and radiative energy of hot spot material depends on the mass-transfer-rate. The sum of both energies overcomes the binding energy at a well defined critical value of the mass-transfer-rate. As long as the transfer-rate is smaller than this critical value RLOF happens conservatively. But as soon as the critical rate is exceeded the gainer will acquire no more than the critical value and RLOF runs into a liberal era. Results: Low-mass binaries never achieve mass-transfer-rates larger than the critical value. Intermediate-mass binaries evolve mainly conservatively but mass will be blown away from the system during the short era of rapid mass-transfer soon after the onset of RLOF. We have calculated the evolution of binaries with a 9 M⊙ primary and a 5.4 M⊙ companion over a range of initial orbital periods, covering case-A RLOF. Mass-loss from the system is achieved during direct impact only. Conclusions: We find systems that show Algolism for more than ten million years. RLOF occurs almost always

  13. The critical spot eraser—a method to interactively control the correction of local hot and cold spots in IMRT planning

    NASA Astrophysics Data System (ADS)

    Süss, Philipp; Bortz, Michael; Küfer, Karl-Heinz; Thieke, Christian

    2013-03-01

    Common problems in inverse radiotherapy planning are localized dose insufficiencies like hot spots in organs at risk or cold spots inside targets. These are hard to correct since the optimization is based on global evaluations like maximum/minimum doses, equivalent uniform doses or dose-volume constraints for whole structures. In this work, we present a new approach to locally correct the dose of any given treatment plan. Once a treatment plan has been found that is acceptable in general but requires local corrections, these areas are marked by the planner. Then the system generates new plans that fulfil the local dose goals. Consequently, it is possible to interactively explore all plans between the locally corrected plans and the original treatment plan, allowing one to exactly adjust the degree of local correction and how the plan changes overall. Both the amount (in Gy) and the size of the local dose change can be navigated. The method is introduced formally as a new mathematical optimization setting, and is evaluated using a clinical example of a meningioma at the base of the skull. It was possible to eliminate a hot spot outside the target volume while controlling the dose changes to all other parts of the treatment plan. The proposed method has the potential to become the final standard step of inverse treatment planning. For more information on this article, see medicalphysicsweb.org

  14. Seismic structure of Cocos and Malpelo Volcanic Ridges and implications for hot spot-ridge interaction

    NASA Astrophysics Data System (ADS)

    SallarèS, Valentí; Charvis, Philippe; Flueh, Ernst R.; Bialas, Joerg

    2003-12-01

    The Cocos and Malpelo Volcanic Ridges are blocks of thickened oceanic crust thought to be the result of the interaction between the Galapagos hot spot and the Cocos-Nazca Spreading Center during the last 20 m.y. In this work we investigate the seismic structure of these two aseismic ridges along three wide-angle transects acquired during the Panama basin and Galapagos plume—New Investigations of Intraplate magmatism (PAGANINI)-1999 experiment. A two-dimensional velocity field with the Moho geometry is obtained using joint refraction/reflection travel time tomography, and the uncertainty and robustness of the results are estimated by performing a Monte Carlo-type analysis. Our results show that the maximum crustal thickness along these profiles ranges from ˜16.5 km (southern Cocos) to ˜19 km (northern Cocos and Malpelo). Oceanic layer 2 thickness is quite uniform regardless of total crustal thickness variations; crustal thickening is mainly accommodated by layer 3. These observations are shown to be consistent with gravity data. The variation of layer 3 velocities is similar along all profiles, being lower where crust is thicker. This leads to an overall anticorrelation between crustal thickness and bulk lower crustal velocity. Since this anticorrelation is contrary to crustal thickening resulting from passive upwelling of abnormally hot mantle, it is necessary to consider active upwelling components and/or some compositional heterogeneities in the mantle source. The NW limit of the Malpelo Ridge shows a dramatic crustal thinning and displays high lower crustal velocities and a poorly defined crust-mantle boundary, suggesting that differential motion along the Coiba transform fault probably separated Regina and Malpelo Ridges.

  15. The structure of HIV-1 genomic RNA in the gp120 gene determines a recombination hot spot in vivo.

    PubMed

    Galetto, Román; Moumen, Abdeladim; Giacomoni, Véronique; Véron, Michel; Charneau, Pierre; Negroni, Matteo

    2004-08-27

    By frequently rearranging large regions of the genome, genetic recombination is a major determinant in the plasticity of the human immunodeficiency virus type I (HIV-1) population. In retroviruses, recombination mostly occurs by template switching during reverse transcription. The generation of retroviral vectors provides a means to study this process after a single cycle of infection of cells in culture. Using HIV-1-derived vectors, we present here the first characterization and estimate of the strength of a recombination hot spot in HIV-1 in vivo. In the hot spot region, located within the C2 portion of the gp120 envelope gene, the rate of recombination is up to ten times higher than in the surrounding regions. The hot region corresponds to a previously identified RNA hairpin structure. Although recombination breakpoints in vivo cluster in the top portion of the hairpin, the bias for template switching in this same region appears less marked in a cell-free system. By modulating the stability of this hairpin we were able to affect the local recombination rate both in vitro and in infected cells, indicating that the local folding of the genomic RNA is a major parameter in the recombination process. This characterization of reverse transcription products generated after a single cycle of infection provides insights in the understanding of the mechanism of recombination in vivo and suggests that specific regions of the genome might be prompted to yield different rates of evolution due to the presence of circumscribed recombination hot spots.

  16. Mapping publication trends and identifying hot spots of research on Internet health information seeking behavior: a quantitative and co-word biclustering analysis.

    PubMed

    Li, Fan; Li, Min; Guan, Peng; Ma, Shuang; Cui, Lei

    2015-03-25

    The Internet has become an established source of health information for people seeking health information. In recent years, research on the health information seeking behavior of Internet users has become an increasingly important scholarly focus. However, there have been no long-term bibliometric studies to date on Internet health information seeking behavior. The purpose of this study was to map publication trends and explore research hot spots of Internet health information seeking behavior. A bibliometric analysis based on PubMed was conducted to investigate the publication trends of research on Internet health information seeking behavior. For the included publications, the annual publication number, the distribution of countries, authors, languages, journals, and annual distribution of highly frequent major MeSH (Medical Subject Headings) terms were determined. Furthermore, co-word biclustering analysis of highly frequent major MeSH terms was utilized to detect the hot spots in this field. A total of 533 publications were included. The research output was gradually increasing. There were five authors who published four or more articles individually. A total of 271 included publications (50.8%) were written by authors from the United States, and 516 of the 533 articles (96.8%) were published in English. The eight most active journals published 34.1% (182/533) of the publications on this topic. Ten research hot spots were found: (1) behavior of Internet health information seeking about HIV infection or sexually transmitted diseases, (2) Internet health information seeking behavior of students, (3) behavior of Internet health information seeking via mobile phone and its apps, (4) physicians' utilization of Internet medical resources, (5) utilization of social media by parents, (6) Internet health information seeking behavior of patients with cancer (mainly breast cancer), (7) trust in or satisfaction with Web-based health information by consumers, (8

  17. Mapping Publication Trends and Identifying Hot Spots of Research on Internet Health Information Seeking Behavior: A Quantitative and Co-Word Biclustering Analysis

    PubMed Central

    Li, Fan; Li, Min; Guan, Peng; Ma, Shuang

    2015-01-01

    Background The Internet has become an established source of health information for people seeking health information. In recent years, research on the health information seeking behavior of Internet users has become an increasingly important scholarly focus. However, there have been no long-term bibliometric studies to date on Internet health information seeking behavior. Objective The purpose of this study was to map publication trends and explore research hot spots of Internet health information seeking behavior. Methods A bibliometric analysis based on PubMed was conducted to investigate the publication trends of research on Internet health information seeking behavior. For the included publications, the annual publication number, the distribution of countries, authors, languages, journals, and annual distribution of highly frequent major MeSH (Medical Subject Headings) terms were determined. Furthermore, co-word biclustering analysis of highly frequent major MeSH terms was utilized to detect the hot spots in this field. Results A total of 533 publications were included. The research output was gradually increasing. There were five authors who published four or more articles individually. A total of 271 included publications (50.8%) were written by authors from the United States, and 516 of the 533 articles (96.8%) were published in English. The eight most active journals published 34.1% (182/533) of the publications on this topic. Ten research hot spots were found: (1) behavior of Internet health information seeking about HIV infection or sexually transmitted diseases, (2) Internet health information seeking behavior of students, (3) behavior of Internet health information seeking via mobile phone and its apps, (4) physicians’ utilization of Internet medical resources, (5) utilization of social media by parents, (6) Internet health information seeking behavior of patients with cancer (mainly breast cancer), (7) trust in or satisfaction with Web-based health

  18. Volcanic hot spot detection from optical multispectral remote sensing data using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Lombardo, Valerio

    2014-03-01

    This paper describes an application of artificial neural networks for the recognition of volcanic lava flow hot spots using remote sensing data. Satellite remote sensing is a very effective and safe way to monitor volcanic eruptions in order to safeguard the environment and the people affected by such natural hazards. Neural networks are an effective and well-established technique for the classification of satellite images. In addition, once well trained, they prove to be very fast in the application stage. In our study a back propagation neural network was used for the recognition of thermal anomalies affecting hot lava pixels. The network was trained using the three thermal channels of the Advanced Very High Resolution Radiometer (AVHRR) sensor as inputs and the corresponding values of heat flux, estimated using a two thermal component model, as reference outputs. As a case study the volcano Etna (Eastern Sicily, Italy) was chosen, and in particular the effusive eruption which took place during the month of 2006 July. The neural network was trained with a time-series of 15 images (12 nighttime images and 3 daytime images) and validated on three independent data sets of AVHRR images of the same eruption and on two relative to an eruption occurred the following month. While for both nighttime and daytime validation images the neural network identified the image pixels affected by hot lava with a 100 per cent success rate, for the daytime images also adjacent pixels were included, apparently not interested by lava flow. Despite these performance differences under different illumination conditions, the proposed method can be considered effective both in terms of classification accuracy and generalization capability. In particular our approach proved to be robust in the rejection of false positives, often corresponding to noisy or cloudy pixels, whose presence in multispectral images can often undermine the performance of traditional classification algorithms. Future

  19. Mutation hot spots in yeast caused by long-range clustering of homopolymeric sequences.

    PubMed

    Ma, Xin; Rogacheva, Maria V; Nishant, K T; Zanders, Sarah; Bustamante, Carlos D; Alani, Eric

    2012-01-26

    Evolutionary theory assumes that mutations occur randomly in the genome; however, studies performed in a variety of organisms indicate the existence of context-dependent mutation biases. Sources of mutagenesis variation across large genomic contexts (e.g., hundreds of bases) have not been identified. Here, we use high-coverage whole-genome sequencing of a conditional mismatch repair mutant line of diploid yeast to identify mutations that accumulated after 160 generations of growth. The vast majority of the mutations accumulated as insertion/deletions (in/dels) in homopolymeric [poly(dA:dT)] and repetitive DNA tracts. Surprisingly, the likelihood of an in/del mutation in a given poly(dA:dT) tract is increased by the presence of nearby poly(dA:dT) tracts in up to a 1,000 bp region centered on the given tract. Our work suggests that specific mutation hot spots can contribute disproportionately to the genetic variation that is introduced into populations and provides long-range genomic sequence context that contributes to mutagenesis. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.

  20. The short arm of chromosome 11 is a hot spot for hypermethylation in human neoplasia

    SciTech Connect

    De Bustros, A.; Nelkin, B.D.; Silverman, A.; Ehrlich, G.; Poiesz, B.; Baylin S.B. )

    1988-08-01

    Inactivation of normally expressed genes may play a role in the formation and/or progression of human cancers. Methylation of cytosine in DNA could potentially participate in such alterations of gene expression. Abnormalities in DNA methylation are a consistent feature of human neoplasms, and the authors now show that these include not only previously recognized widespread genomic hypomethylation, but also regional increases in gene methylation. A hot spot for abnormal methylation of C + G-rich areas has been detected on the short arm of chromosome 11 in an area known to harbor tumor suppressor genes. This change occurs consistently in common forms of human cancer and appears early during the transformation of cells with viruses including members of the human T-cell leukemia (HTLV) family. Furthermore, in one chromosome 11 gene examined, calcitonin, the increased methylation in somatic tumor cells coincides with the presence of an inactive chromatin pattern in the transcriptional regulatory area. The increased regional DNA methylation demonstrated may then participate in or mark chromosomal changes associated with gene inactivation events that are central to the genesis and/or progression of human cancers.

  1. Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark ocean

    PubMed Central

    Mattes, Timothy E; Nunn, Brook L; Marshall, Katharine T; Proskurowski, Giora; Kelley, Deborah S; Kawka, Orest E; Goodlett, David R; Hansell, Dennis A; Morris, Robert M

    2013-01-01

    Bacteria and archaea in the dark ocean (>200 m) comprise 0.3–1.3 billion tons of actively cycled marine carbon. Many of these microorganisms have the genetic potential to fix inorganic carbon (autotrophs) or assimilate single-carbon compounds (methylotrophs). We identified the functions of autotrophic and methylotrophic microorganisms in a vent plume at Axial Seamount, where hydrothermal activity provides a biogeochemical hot spot for carbon fixation in the dark ocean. Free-living members of the SUP05/Arctic96BD-19 clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout the northeastern Pacific Ocean and dominated hydrothermal plume waters at Axial Seamount. Marine GSOs expressed proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system), dissimilatory sulfite reductase and ATP sulfurylase), carbon fixation (ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO)), aerobic respiration (cytochrome c oxidase) and nitrogen regulation (PII). Methylotrophs and iron oxidizers were also active in plume waters and expressed key proteins for methane oxidation and inorganic carbon fixation (particulate methane monooxygenase/methanol dehydrogenase and RuBisCO, respectively). Proteomic data suggest that free-living sulfur oxidizers and methylotrophs are among the dominant primary producers in vent plume waters in the northeastern Pacific Ocean. PMID:23842654

  2. Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark ocean.

    PubMed

    Mattes, Timothy E; Nunn, Brook L; Marshall, Katharine T; Proskurowski, Giora; Kelley, Deborah S; Kawka, Orest E; Goodlett, David R; Hansell, Dennis A; Morris, Robert M

    2013-12-01

    Bacteria and archaea in the dark ocean (>200 m) comprise 0.3-1.3 billion tons of actively cycled marine carbon. Many of these microorganisms have the genetic potential to fix inorganic carbon (autotrophs) or assimilate single-carbon compounds (methylotrophs). We identified the functions of autotrophic and methylotrophic microorganisms in a vent plume at Axial Seamount, where hydrothermal activity provides a biogeochemical hot spot for carbon fixation in the dark ocean. Free-living members of the SUP05/Arctic96BD-19 clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout the northeastern Pacific Ocean and dominated hydrothermal plume waters at Axial Seamount. Marine GSOs expressed proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system), dissimilatory sulfite reductase and ATP sulfurylase), carbon fixation (ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO)), aerobic respiration (cytochrome c oxidase) and nitrogen regulation (PII). Methylotrophs and iron oxidizers were also active in plume waters and expressed key proteins for methane oxidation and inorganic carbon fixation (particulate methane monooxygenase/methanol dehydrogenase and RuBisCO, respectively). Proteomic data suggest that free-living sulfur oxidizers and methylotrophs are among the dominant primary producers in vent plume waters in the northeastern Pacific Ocean.

  3. Hot spot-mediated non-dissipative and ultrafast plasmon passage.

    PubMed

    Roller, Eva-Maria; Besteiro, Lucas V; Pupp, Claudia; Khorashad, Larousse Khosravi; Govorov, Alexander O; Liedl, Tim

    2017-08-01

    Plasmonic nanoparticles hold great promise as photon handling elements and as channels for coherent transfer of energy and information in future all-optical computing devices.1-5 Coherent energy oscillations between two spatially separated plasmonic entities via a virtual middle state exemplify electron-based population transfer, but their realization requires precise nanoscale positioning of heterogeneous particles.6-10 Here, we show the assembly and optical analysis of a triple particle system consisting of two gold nanoparticles with an inter-spaced silver island. We observe strong plasmonic coupling between the spatially separated gold particles mediated by the connecting silver particle with almost no dissipation of energy. As the excitation energy of the silver island exceeds that of the gold particles, only quasi-occupation of the silver transfer channel is possible. We describe this effect both with exact classical electrodynamic modeling and qualitative quantum-mechanical calculations. We identify the formation of strong hot spots between all particles as the main mechanism for the loss-less coupling and thus coherent ultra-fast energy transfer between the remote partners. Our findings could prove useful for quantum gate operations, but also for classical charge and information transfer processes.

  4. Breakdown into nanoscale of graphene oxide: Confined hot spot atomic reduction and fragmentation

    PubMed Central

    Gonçalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andrés, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Luís D.; Grácio, José; Marques, Paula A. A. P.

    2014-01-01

    Nano-graphene oxide (nano-GO) is a new class of carbon based materials being proposed for biomedical applications due to its small size, intrinsic optical properties, large specific surface area, and easy to functionalize. To fully exploit nano-GO properties, a reproducible method for its production is of utmost importance. Herein we report, the study of the sequential fracture of GO sheets onto nano-GO with controllable lateral width, by a simple, and reproducible method based on a mechanism that we describe as a confined hot spot atomic fragmentation/reduction of GO promoted by ultrasonication. The chemical and structural changes on GO structure during the breakage were monitored by XPS, FTIR, Raman and HRTEM. We found that GO sheets starts breaking from the defects region and in a second phase through the disruption of carbon bonds while still maintaining crystalline carbon domains. The breaking of GO is accompanied by its own reduction, essentially by the elimination of carboxylic and carbonyl functional groups. Photoluminescence and photothermal studies using this nano-GO are also presented highlighting the potential of this nanomaterial as a unique imaging/therapy platform. PMID:25339424

  5. Fermi surface topology and hot spot distribution in the Kondo lattice system CeB6

    DOE PAGES

    Neupane, Madhab; Alidoust, Nasser; Belopolski, Ilya; ...

    2015-09-18

    Rare-earth hexaborides have attracted considerable attention recently in connection to a variety of correlated phenomena including heavy fermions, superconductivity, and low-temperature magnetic phases. Here, we present high-resolution angle-resolved photoemission spectroscopy studies of trivalent CeB6 and divalent BaB6 rare-earth hexaborides. Here we find that the Fermi surface electronic structure of CeB6 consists of large oval-shaped pockets around the X points of the Brillouin zone, whereas the states around the zone center Γ point are strongly renormalized. Our first-principles calculations agree with our experimental results around the X points but not around the Γ point, indicating areas of strong renormalization located nearmore » Γ. The Ce quasiparticle states participate in the formation of hot spots at the Fermi surface, whereas the incoherent f states hybridize and lead to the emergence of dispersive features absent in the non-$f$ counterpart BaB6. Lastly, our results provide an understanding of the electronic structure in rare-earth hexaborides, which will be useful in elucidating the nature of the exotic low-temperature phases in these materials.« less

  6. A Machine Learning Approach for Hot-Spot Detection at Protein-Protein Interfaces

    PubMed Central

    Melo, Rita; Fieldhouse, Robert; Melo, André; Correia, João D. G.; Cordeiro, Maria Natália D. S.; Gümüş, Zeynep H.; Costa, Joaquim; Bonvin, Alexandre M. J. J.; Moreira, Irina S.

    2016-01-01

    Understanding protein-protein interactions is a key challenge in biochemistry. In this work, we describe a more accurate methodology to predict Hot-Spots (HS) in protein-protein interfaces from their native complex structure compared to previous published Machine Learning (ML) techniques. Our model is trained on a large number of complexes and on a significantly larger number of different structural- and evolutionary sequence-based features. In particular, we added interface size, type of interaction between residues at the interface of the complex, number of different types of residues at the interface and the Position-Specific Scoring Matrix (PSSM), for a total of 79 features. We used twenty-seven algorithms from a simple linear-based function to support-vector machine models with different cost functions. The best model was achieved by the use of the conditional inference random forest (c-forest) algorithm with a dataset pre-processed by the normalization of features and with up-sampling of the minor class. The method has an overall accuracy of 0.80, an F1-score of 0.73, a sensitivity of 0.76 and a specificity of 0.82 for the independent test set. PMID:27472327

  7. Hydrothermal Plume Activity at Teahitia Seamount: Re-Awakening of the Society Islands Hot-Spot?

    NASA Astrophysics Data System (ADS)

    German, C. R.; Xu, G.; Yeo, I. A.; Walker, S. L.; Moffett, J.; Cutter, G. A.; Devey, C. W.; Hyvernaud, O.; Reymond, D.; Resing, J. A.

    2016-12-01

    We report results from a combined mapping and CTD-rosette investigation of the summit of Teahitia Seamount, Society Islands hot-spot, that indicates that high temperature venting may have been present by late 2013 at a site that only hosted low-temperature vents ( 30°C) when previously visited by submersible, 25 years earlier. In 2013, a non-buoyant hydrothermal plume containing high concentrations (>100nmol/L) of both dissolved and total dissolvable Fe was observed at an apparent rise-height of 110-140m above a seafloor source at 1500-1530m water depth, implying a heat-flux for the underlying venting of 13-35MW. From a comparison to the past evolution of venting at Loihi seamount (Hawaii), coupled with an examination of recent seismicity detected by the Polynesian Seismic Network, we hypothesize that venting at Teahitia may have undergone perturbation only recently and that this, in turn, may be linked to a re-awakening of the Society Islands hotspot.

  8. Mehetia Island, South Pacific: geology and petrology of the emerged part of the Society hot spot

    NASA Astrophysics Data System (ADS)

    Binard, N.; Maury, R. C.; Guille, G.; Talandier, J.; Gillot, P. Y.; Cotten, J.

    1993-03-01

    Mehetia is the youngest island of the Society hot-spot chain, representing the summit of a large submarine volcanic edifice (4035 m in height). Its conical shape results from strombolian-type eruptions. Mehetia comprises two major volcanic formations. The "old edifice" made up of interbedded pyroclastic rocks and lava flows, forms the main part of the island. The base of its stratigraphic pile is dated at 70,000-75,000 yr B.P. by K/Ar. Younger events (⩽ 31,000 yr B.P.) have built up a volcanic cone, with a summit hydromagmatic crater, and emplaced lava flows extending south of the island where they overlie coral reef limestones. Between the two eruptive periods, an erosional phase caused the partial destruction of the old edifice. Six successive stages of construction of the island are described from stratigraphic relations. Mehetia does not show any indication of present-day volcanic or fumarolic activity but should be considered as an active volcano as evidenced by the 1981 volcanoseismic crisis. Mehetia lavas include oceanites, primitive and evolved alkali basalts and basanites together with rare hawaiites and mugearites. Two main petrogenetic processes (i.e. accumulation and crystal fractionation) are inferred from bulk-rock composition and microprobe data on phenocrysts. Oceanites are derived from basalts through accumulation of olivine and clinopyroxene. Major and trace elements trends suggest evolution through crystal fractionation processes involving olivine, clinopyroxene, and Fe-Ti oxides.

  9. Coincident ruddy turnstone migration and horseshoe crab spawning creates an ecological 'hot spot' for influenza viruses.

    PubMed

    Krauss, Scott; Stallknecht, David E; Negovetich, Nicholas J; Niles, Lawrence J; Webby, Richard J; Webster, Robert G

    2010-11-22

    Since 1985, avian influenza virus surveillance has been conducted annually from mid-May to early June in charadriiform species from the families Scolopacidae and Laridae (shorebirds and gulls) at Delaware Bay in the northeast United States. The mass migrations of shorebirds, gulls and horseshoe crabs (Limulus polyphemus) coincide at that time, and large numbers of migrating birds pause at Delaware Bay to feed on horseshoe crab eggs deposited at the high-tide line. Influenza viruses are consistently isolated from charadriiform birds at Delaware Bay, at an overall rate approximately 17 times the combined rate of isolation at all other surveillance sites worldwide (490 isolates/9474 samples, 5.2% versus 49 isolates per 15,848 samples, 0.3%, respectively; Proportion test, p < 0.0001). The likelihood of isolating influenza viruses at Delaware Bay is dependent on the presence of ruddy turnstone (Arenaria interpres) at the sampling site (G-test of independence, p < 0.001). The convergence of host factors and environmental factors results in a unique ecological 'hot spot' for influenza viruses in Charadriiformes.

  10. Western U.S. Infrasonic Catalog: Illuminating infrasonic hot spots with the USArray

    NASA Astrophysics Data System (ADS)

    Walker, Kristoffer T.; Shelby, Richard; Hedlin, Michael A. H.; de Groot-Hedlin, Catherine; Vernon, Frank

    2011-12-01

    In this study reverse time migration is applied to signals recorded by the 2007-08 USArray, presumably due to acoustic-to-seismic coupling, to detect and locate in two-dimensional space and time 901 sources of atmospheric infrasound, defining the Western United States Infrasonic Catalog (WUSIC). The detections are visually inspected and ranked. Uncertainties are estimated using a bootstrap technique. The method correctly locates most rocket motor detonations in Utah and a bolide explosion in Oregon with an average spatial accuracy of 50 km and 25 km, respectively. The origin time statistics for 2007 and 2008 events are nearly identical and suggest a predominant human origin. The event locations illuminate repeating sources of infrasound, or "infrasonic hot spots," in Nevada, Utah, and Idaho that are spatially associated with active military areas. The infrasonic arrivals comprise several branches that are observed to a range between 200 and 1500 km to the east and west of the epicenter in the winter and summer, respectively. The optimum group velocities are Gaussian distributed and centered at 295 m/s. A seasonal variation in optimum group velocities exhibits good correlation with atmospheric temperature. The results show that relatively dense seismic networks fill in the gaps between sparsely located infrasound arrays and provide valuable information for regional infrasonic source location and propagation studies. Specifically, the catalogs presented here can be used to statistically validate and improve propagation models, especially above the middle stratosphere where winds are not directly measured by ground-based weather stations or meteorological satellites.

  11. Hot spot detection and spatio-temporal dynamics of dengue in Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Naish, S.; Tong, S.

    2014-11-01

    Dengue has been a major public health concern in Australia since it re-emerged in Queensland in 1992-1993. This study explored spatio-temporal distribution and clustering of locally-acquired dengue cases in Queensland State, Australia and identified target areas for effective interventions. A computerised locally-acquired dengue case dataset was collected from Queensland Health for Queensland from 1993 to 2012. Descriptive spatial and temporal analyses were conducted using geographic information system tools and geostatistical techniques. Dengue hot spots were detected using SatScan method. Descriptive spatial analysis showed that a total of 2,398 locally-acquired dengue cases were recorded in central and northern regions of tropical Queensland. A seasonal pattern was observed with most of the cases occurring in autumn. Spatial and temporal variation of dengue cases was observed in the geographic areas affected by dengue over time. Tropical areas are potential high-risk areas for mosquito-borne diseases such as dengue. This study demonstrated that the locally-acquired dengue cases have exhibited a spatial and temporal variation over the past twenty years in tropical Queensland, Australia. There is a clear evidence for the existence of statistically significant clusters of dengue and these clusters varied over time. These findings enabled us to detect and target dengue clusters suggesting that the use of geospatial information can assist the health authority in planning dengue control activities and it would allow for better design and implementation of dengue management programs.

  12. Models of lithosphere and asthenosphere anisotropic structure of the Yellowstone hot spot from shear wave splitting

    NASA Astrophysics Data System (ADS)

    Waite, Gregory P.; Schutt, Derek L.; Smith, Robert B.

    2005-11-01

    Teleseismic shear wave splitting measured at 56 continuous and temporary seismographs deployed in a 500 km by 600 km area around the Yellowstone hot spot indicates that fast anisotropy in the mantle is parallel to the direction of plate motion under most of the array. The average split time from all stations of 0.9 s is typical of continental stations. There is little evidence for plume-induced radial strain, suggesting that any contribution of gravitationally spreading plume material is undetectably small with respect to the plate motion velocity. Two stations within Yellowstone have splitting measurements indicating the apparent fast anisotropy direction (ϕ) is nearly perpendicular to plate motion. These stations are ˜30 km from stations with ϕ parallel to plate motion. The 70° rotation over 30 km suggests a shallow source of anisotropy; however, split times for these stations are more than 2 s. We suggest melt-filled, stress-oriented cracks in the lithosphere are responsible for the anomalous ϕ orientations within Yellowstone. Stations southeast of Yellowstone have measurements of ϕ oriented NNW to WNW at high angles to the plate motion direction. The Archean lithosphere beneath these stations may have significant anisotropy capable of producing the observed splitting.

  13. DIESEL TRUCK IDLING EMISSIONS - MEASUREMENTS AT A PM2.5 HOT SPOT

    SciTech Connect

    Parks, II, James E; Miller, Terry L.; Storey, John Morse; Fu, Joshua S.; Hromis, Boris

    2007-01-01

    The University of Tennessee and Oak Ridge National Laboratory conducted a 5-month long air monitoring study at the Watt Road interchange on I-40 in Knoxville Tennessee where there are 20,000 heavy-duty trucks per day traveling the interstate. In addition, there are 3 large truck stops at this interchange where as many as 400 trucks idle engines at night. As a result, high levels of PM2.5 were measured near the interchange often exceeding National Ambient Air Quality Standards. This paper presents the results of the air monitoring study illustrating the hourly, day-of-week, and seasonal patterns of PM2.5 resulting from diesel truck emissions on the interstate and at the truck stops. Surprisingly, most of the PM2.5 concentrations occurred during the night when the largest contribution of emissions was from idling trucks rather than trucks on the interstate. A nearby background air monitoring site was used to identify the contribution of regional PM2.5 emissions which also contribute significantly to the concentrations measured at the site. The relative contributions of regional background, local truck idling and trucks on the interstate to local PM2.5 concentrations are presented and discussed in the paper. The results indicate the potential significance of diesel truck idling emissions to the occurrence of hot-spots of high PM2.5 concentrations near large truck stops, ports or border crossings.

  14. Simulated impact of self-generated magnetic fields in the hot-spot of NIF implosions

    NASA Astrophysics Data System (ADS)

    Partha, M. A.; Haan, S. W.; Koning, J.; Marinak, M. M.; Weber, C. R.; Clark, D. S.

    2016-10-01

    Deviations from sphericity in an imploded hot-spot result in magnetic fields generated by the Biermann battery effect. The magnetic field can reduce thermal conductivity, affect α transport, change instability growth, and cause magnetic pressure. Previous estimates of these effects have indicated that they are not of great consequence, but have suggested that they could plausibly affect NIF observables such as yield and ion temperature by 5-25%. Using the MHD capability in the Hydra code, we evaluated the impact of these processes in a post-shot model for a typical NIF implosion. Various implosion asymmetries were implemented, with the goal of surveying plausible implosion configurations to find the geometry in which the MHD effects were the most significant. Magnetic fields are estimated to approach 104 Tesla, and to affect conductivity locally by more than 50%, but global impact on observables is small in most cases. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  15. Description of spatial patterns of radionuclide deposition by lognormal distribution and hot spots.

    PubMed

    Grubich, Andry; Makarevich, V I; Zhukova, O M

    2013-12-01

    Spatial distributions of activity density (kBq/m(2)) and activity concentration (Bq/kg) are studied on sites with non-cultivated soils. Fitting datasets with lognormal, Weibull and normal distributions with sampling size n ≥ 60 showed that radionuclide deposition ((90)Sr, (137)Cs, (238)Pu, (239+240)Pu, (241)Am) due to Chernobyl fallout no more than in 10% of cases are described by Weibull distribution, and in the rest of the cases--by lognormal distribution. However asymptotics of "righthand tail" of empirical (sample) distribution quite often differs from the right-hand tail asymptotics of lognormal distribution. Thereby lognormal distribution is only an approximate statistical model of radionuclides' spatial pattern. Estimates of site surface area with "hot spots" are considered. Also distributions of (137)Cs and (134)Cs activity concentration on the territory contaminated by Fukushima fallout are reviewed. Characteristics of activity concentration for Fukushima and Chernobyl fallouts are collated. The results obtained make it possible to suggest that in both cases spatial contaminations of soil are described by approximately the same statistical models. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. A Machine Learning Approach for Hot-Spot Detection at Protein-Protein Interfaces.

    PubMed

    Melo, Rita; Fieldhouse, Robert; Melo, André; Correia, João D G; Cordeiro, Maria Natália D S; Gümüş, Zeynep H; Costa, Joaquim; Bonvin, Alexandre M J J; Moreira, Irina S

    2016-07-27

    Understanding protein-protein interactions is a key challenge in biochemistry. In this work, we describe a more accurate methodology to predict Hot-Spots (HS) in protein-protein interfaces from their native complex structure compared to previous published Machine Learning (ML) techniques. Our model is trained on a large number of complexes and on a significantly larger number of different structural- and evolutionary sequence-based features. In particular, we added interface size, type of interaction between residues at the interface of the complex, number of different types of residues at the interface and the Position-Specific Scoring Matrix (PSSM), for a total of 79 features. We used twenty-seven algorithms from a simple linear-based function to support-vector machine models with different cost functions. The best model was achieved by the use of the conditional inference random forest (c-forest) algorithm with a dataset pre-processed by the normalization of features and with up-sampling of the minor class. The method has an overall accuracy of 0.80, an F1-score of 0.73, a sensitivity of 0.76 and a specificity of 0.82 for the independent test set.

  17. CROI 2016: Hot Spots in HIV Infection and Advances in HIV Prevention.