WorldWideScience

Sample records for grounding line retreat

  1. Grounding line retreat of Pope, Smith, and Kohler Glaciers, West Antarctica, measured with Sentinel-1a radar interferometry data

    Science.gov (United States)

    Scheuchl, B.; Mouginot, J.; Rignot, E.; Morlighem, M.; Khazendar, A.

    2016-08-01

    We employ Sentinel-1a C band satellite radar interferometry data in Terrain Observation with Progressive Scans mode to map the grounding line and ice velocity of Pope, Smith, and Kohler glaciers, in West Antarctica, for the years 2014-2016 and compare the results with those obtained using Earth Remote Sensing Satellites (ERS-1/2) in 1992, 1996, and 2011. We observe an ongoing, rapid grounding line retreat of Smith at 2 km/yr (40 km since 1996), an 11 km retreat of Pope (0.5 km/yr), and a 2 km readvance of Kohler since 2011. The variability in glacier retreat is consistent with the distribution of basal slopes, i.e., fast along retrograde beds and slow along prograde beds. We find that several pinning points holding Dotson and Crosson ice shelves disappeared since 1996 due to ice shelf thinning, which signal the ongoing weakening of these ice shelves. Overall, the results indicate that ice shelf and glacier retreat in this sector remain unabated.

  2. Magnetic reconnection by a self-retreating X line.

    Science.gov (United States)

    Oka, M; Fujimoto, M; Nakamura, T K M; Shinohara, I; Nishikawa, K-I

    2008-11-14

    Particle-in-cell simulations of collisionless magnetic reconnection are performed to study asymmetric reconnection in which an outflow is blocked by a hard wall while leaving sufficiently large room for the outflow of the opposite direction. This condition leads to a slow, roughly constant motion of the diffusion region away from the wall, the so-called "X-line retreat." The typical retreat speed is approximately 0.1 times the Alfvén speed. At the diffusion region, ion flow pattern shows strong asymmetry and the ion stagnation point and the X line are not collocated. A surprise, however, is that the reconnection rate remains the same unaffected by the retreat motion.

  3. Magnetic Reconnection by a Self-Retreating X-Line

    CERN Document Server

    Oka, M; Nakamura, T K M; Shinohara, I; Nishikawa, K -I

    2008-01-01

    Particle-in-cell (PIC) simulations of collisionless magnetic reconnection are performed to study asymmetric reconnection in which an outflow is blocked by a hard wall while leaving sufficiently large room for the outflow of the opposite direction. This condition leads to a slow, roughly constant motion of the diffusion region away from the wall, the so-called `X-line retreat'. The typical retreat speed is ~0.1 times the Alfven speed. At the diffusion region, ion flow pattern shows strong asymmetry and the ion stagnation point and the X-line are not collocated. A surprise, however, is that the reconnection rate remains the same unaffected by the retreat motion.

  4. Structure and form of grounding lines of modern ice sheets

    Science.gov (United States)

    Tinto, K. J.; Bell, R. E.; Cochran, J. R.; Boghosian, A.; Porter, D. F.

    2015-12-01

    The form of the bed at the grounding line of a glacier and the character of the underlying rock can be critical to the stability of the glacier. Aerogravity measurements offer a unique insight in to the character of the grounding line environment. By combining depth measurements from further onshore radar and geological information from magnetic surveys, gravity-based models can reveal both the depth and slope of the bed at the grounding line. Where bed elevation is known at the grounding line, gravity models can show the density structure of the underlying rock. Operation IceBridge has flown coincident radar, lidar, photography, gravity and magnetic airborne surveys along fjords and over ice shelves in both Greenland and Antarctica. Aerogravity measurements have been used extensively to model the bathymetry of the sea floor in front of the grounding line, and to identify the depth of the grounding line in areas where radar measurements have proven challenging. These models have also been used to reveal the range of conditions at present day grounding lines, as well as those experienced in the past and predicted for future grounding line positions. In some regions, we have identified low-density sediment accumulations, at both present day grounding lines and within fjords, that we interpret to be terminal moraines deposited by the glacier itself during hiatuses in retreat. In other regions, we find that the present day grounding line is stalled on a ridge of high-density rock. Ridges such as these remain in the same position through many cycles of advance and retreat of the glacier. Our synthesis of gravity data from a wide range of glacial environments can be used to identify likely drivers of change at the grounding line, whether this is the depth, the slope, or the geological character of the glacier bed.

  5. Hydrostatic grounding line parameterization in ice sheet models

    Directory of Open Access Journals (Sweden)

    H. Seroussi

    2014-06-01

    Full Text Available Modeling of grounding line migration is essential to simulate accurately the behavior of marine ice sheets and investigate their stability. Here, we assess the sensitivity of numerical models to the parameterization of the grounding line position. We run the MISMIP3D benchmark experiments using a two-dimensional shelfy-stream approximation (SSA model with different mesh resolutions and different sub-element parameterizations of grounding line position. Results show that different grounding line parameterizations lead to different steady state grounding line positions as well as different retreat/advance rates. Our simulations explain why some vertically depth-averaged model simulations exhibited behaviors similar to full-Stokes models in the MISMIP3D benchmark, while the vast majority of simulations based on SSA showed results deviating significantly from full-Stokes results. The results reveal that differences between simulations performed with and without sub-element parameterization are as large as those performed with different approximations of the stress balance equations and that the reversibility test can be passed at much lower resolutions than the steady-state grounding line position. We conclude that fixed grid models that do not employ such a parameterization should be avoided, as they do not provide accurate estimates of grounding line dynamics, even at high spatial resolution. For models that include sub-element grounding line parameterization, a mesh resolution lower than 2 km should be employed.

  6. Resistive magnetohydrodynamic simulations of X-line retreat during magnetic reconnection

    CERN Document Server

    Murphy, N A

    2010-01-01

    To investigate the impact of current sheet motion on the reconnection process, we perform resistive magnetohydrodynamic (MHD) simulations of two closely located reconnection sites which move apart from each other as reconnection develops. This simulation develops less quickly than an otherwise equivalent single perturbation simulation but eventually exhibits a higher reconnection rate. The unobstructed outflow jets are faster and longer than the outflow jets directed towards the magnetic island that forms between the two current sheets. The X-line and flow stagnation point are located near the trailing end of each current sheet very close to the obstructed exit. The speed of X-line retreat ranges from ~0.02-0.06 while the speed of stagnation point retreat ranges from ~0.03-0.07, in units of the initial upstream Alfven velocity. Early in time, the flow stagnation point is located closer to the center of the current sheet than the X-line, but later on the relative positions of these two points switch. Consequen...

  7. Continued retreat of Thwaites Glacier, West Antarctica, controlled by bed topography and ocean circulation

    Science.gov (United States)

    Seroussi, H.; Nakayama, Y.; Larour, E.; Menemenlis, D.; Morlighem, M.; Rignot, E.; Khazendar, A.

    2017-06-01

    The Amundsen Sea sector is experiencing the largest mass loss, glacier acceleration, and grounding line retreat in Antarctica. Enhanced intrusion of Circumpolar Deep Water onto the continental shelf has been proposed as the primary forcing mechanism for the retreat. Here we investigate the dynamics and evolution of Thwaites Glacier with a novel, fully coupled, ice-ocean numerical model. We obtain a significantly improved agreement with the observed pattern of glacial retreat using the coupled model. Coupled simulations over the coming decades indicate a continued mass loss at a sustained rate. Uncoupled simulations using a depth-dependent parameterization of sub-ice-shelf melt significantly overestimate the rate of grounding line retreat compared to the coupled model, as the parameterization does not capture the complexity of the ocean circulation associated with the formation of confined cavities during the retreat. Bed topography controls the pattern of grounding line retreat, while oceanic thermal forcing impacts the rate of grounding line retreat. The importance of oceanic forcing increases with time as Thwaites grounding line retreats farther inland.

  8. Retreat, Hell!

    Science.gov (United States)

    Sims, Wil

    1978-01-01

    Describes an annual fall retreat for junior college newspaper staffs, which involves a program of workshops and discussions about problems, goals, and staff members' roles; offers advice on planning such a retreat. (GW)

  9. New Gravity-Derived Grounding Line Depths Highlight Role Bathymetry Plays in Ongoing Greenland Ice Sheet Change

    Science.gov (United States)

    Boghosian, A.; Porter, D. F.; Tinto, K. J.; Bell, R. E.; Cochran, J. R.; Csatho, B. M.

    2014-12-01

    Bathymetry has been a missing piece in understanding ice-ocean interactions of marine-terminating glaciers in Greenland. As bathymetry in fjords often controls the flow of warm water to the terminus of the glacier, and the grounding line depth of the glacier can modulate the effect of this warm water on the glacier. Study of Tracy and Heilprin Glaciers, a pair of neighboring glaciers in northwest Greenland, has indicated that when exposed to similar external forcings, the glacier with the deeper grounding line will retreat more rapidly. The new comprehensive mapping of grounding line depths with Operation IceBridge gravity inversions provides the basis for examining this question for all of Greenland's glaciers. We consider 54 distinct glaciers in our analysis. Grounding line depths for these 54 come from data collected by Operation IceBridge from 2010-2012. New grounding line depths for 36 glaciers are derived from gravity measurements in locations where radar is unable to retrieve grounding line depths. 18 grounding line depths come from CReSIS Multichannel Coherent Depth Sounder radar data. Offshore bathymetry in all 54 fjords is gravity-derived. The gravity-derived bathymetry is always constrained onshore by radar, and when possible pinned offshore to acoustic bathymetric measurements.Here we present the gravity-derived grounding line depths along with recent glacier behavior, including surface lowering and terminus retreat, of these 54 glaciers. In general, the glaciers with deeper grounding lines are experiencing greater mass loss. This relationship between grounding line depth and mass balance extends to much of Greenland. We systematically discuss this relationship in the different major regions of Greenland, and note that the relationship is strongest in the southeast, and weakest in the north.

  10. Full-Stokes modeling of grounding line dynamics, ice melt and iceberg calving for Thwaites Glacier, West Antarctica

    OpenAIRE

    Yu, Hongju; Rignot, Eric; Morlighem, Mathieu; Seroussi, Helene

    2016-01-01

    Thwaites Glacier (TG), West Antarctica, has been losing mass and retreating rapidly in the past three decades. Here we present a two-dimensional, Full-Stokes (FS) modeling study of the grounding line dynamics and iceberg calving of TG. First, we compare FS with two simplified models, the higher-order (HO) model and the shallow-shelf approximation (SSA) model, to determine the impact of changes in ice shelf basal melt rate on grounding line dynamics. Second, we combine FS with the Linear Elast...

  11. Ground Loop Impedance of Long EHV Cable Lines

    DEFF Research Database (Denmark)

    Ohno, Teruo; Bak, Claus Leth; Sørensen, Thomas K.

    2012-01-01

    The distance protection scheme without communication is often applied to the backup protection of EHV cable lines. For a reliable operation of a ground distance relay, the ground loop impedance of EHV cable lines needs to have a linear relationship to the distance from the relay location to the f...

  12. Ground Fault Line Selection with Improved Residual Flow Incremental Method

    Directory of Open Access Journals (Sweden)

    Wenhong Li

    2013-08-01

    Full Text Available According to the shortcoming of single-phase ground fault line selection method in the resonant grounded system such as the uncertainty of its device by fast compensation with the automatic compensation equipment, an arc suppression and residual flow incremental method is proposed to effectively choose the earth fault line. Firstly, when the single-phase ground fault occurs, the arc suppression coil parameters are adjusted to realize compensation and arc suppression. Then the arc suppression coil inductance values are modulated to make the zero-sequence current of fault line changed, at the same time, the zero-sequence current value is detected and its change will be captured to select the fault line. The simulation experiments prove that the arc grounding over voltage damage can be effectively reduced by arc suppression coil full compensation and fault line can be effectively selected by arc suppression and residual flow increment method.

  13. Multi-temporal retreat rates along the eastern Mediterranean coastal cliff

    Science.gov (United States)

    Katz, O.; Mushkin, A.

    2012-12-01

    The Israeli coastal cliff extends about 50 km along the eastern Mediterranean shores. The cliff is comprised of late Quaternary eolianites and paleosols and reaches heights of up to 50 meters. In places, time-averaged inland cliff-top retreat rates of up to a few tens of centimeters per year have been measured usually by comparing aerial photos from the last decades. Commonly, these locally constrained retreat rates have been: 1) extrapolated as representative of the entire cliff length, and 2) adopted by hazard-mitigation and planning authorities. Here, we re-evaluate the current understanding of coastal-retreat patterns and rates along Israel's Mediterranean cliff line using a suite of field observations, aerial photography and recently obtained airborne and ground based high resolution LiDAR measurement of cliff morphologies. First, we constrain the decadal-scale retreat rates along the coastal-cliff by comparing the cliff-top location in 1945 and 2004 using aerial photos. We find a statistically significant spatial correlation between: 1) calculated low retreat rates (less than 0.1 m/yr) and field-based criteria indicating overall stability: slope angle of 45 deg. and talus cover along the lower part of the cliff and developed vegetation cover, and 2) high retreat rates and field criteria indicating recent instability: fresh landslide scars and 'hanging' valleys, which provides independent support for the calculated retreat rates. Calculated 60 years average cliff-top retreat rates of less than 0.1, 0.2 and 0.3 m/yr along 58%, 77% and 85% of the cliff length, respectively, reveal that extended stretches of the cliff line did not experience detectable retreat in the past 60 years, thus implying relative stability of 50% of Israel's costal cliffs during this time period. Second, we constrain the annual retreat rates using repeat high-resolution ground based LiDAR surveys before and after an extreme winter storm that occurred in Dec. 2010. Locally, storm induced

  14. Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier.

    Science.gov (United States)

    Smith, J A; Andersen, T J; Shortt, M; Gaffney, A M; Truffer, M; Stanton, T P; Bindschadler, R; Dutrieux, P; Jenkins, A; Hillenbrand, C-D; Ehrmann, W; Corr, H F J; Farley, N; Crowhurst, S; Vaughan, D G

    2017-01-05

    The West Antarctic Ice Sheet is one of the largest potential sources of rising sea levels. Over the past 40 years, glaciers flowing into the Amundsen Sea sector of the ice sheet have thinned at an accelerating rate, and several numerical models suggest that unstable and irreversible retreat of the grounding line-which marks the boundary between grounded ice and floating ice shelf-is underway. Understanding this recent retreat requires a detailed knowledge of grounding-line history, but the locations of the grounding line before the advent of satellite monitoring in the 1990s are poorly dated. In particular, a history of grounding-line retreat is required to understand the relative roles of contemporaneous ocean-forced change and of ongoing glacier response to an earlier perturbation in driving ice-sheet loss. Here we show that the present thinning and retreat of Pine Island Glacier in West Antarctica is part of a climatically forced trend that was triggered in the 1940s. Our conclusions arise from analysis of sediment cores recovered beneath the floating Pine Island Glacier ice shelf, and constrain the date at which the grounding line retreated from a prominent seafloor ridge. We find that incursion of marine water beyond the crest of this ridge, forming an ocean cavity beneath the ice shelf, occurred in 1945 (±12 years); final ungrounding of the ice shelf from the ridge occurred in 1970 (±4 years). The initial opening of this ocean cavity followed a period of strong warming of West Antarctica, associated with El Niño activity. Thus our results suggest that, even when climate forcing weakened, ice-sheet retreat continued.

  15. Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier

    Science.gov (United States)

    Smith, J. A.; Andersen, T. J.; Shortt, M.; Gaffney, A. M.; Truffer, M.; Stanton, T. P.; Bindschadler, R.; Dutrieux, P.; Jenkins, A.; Hillenbrand, C.-D.; Ehrmann, W.; Corr, H. F. J.; Farley, N.; Crowhurst, S.; Vaughan, D. G.

    2016-11-01

    The West Antarctic Ice Sheet is one of the largest potential sources of rising sea levels. Over the past 40 years, glaciers flowing into the Amundsen Sea sector of the ice sheet have thinned at an accelerating rate, and several numerical models suggest that unstable and irreversible retreat of the grounding line—which marks the boundary between grounded ice and floating ice shelf—is underway. Understanding this recent retreat requires a detailed knowledge of grounding-line history, but the locations of the grounding line before the advent of satellite monitoring in the 1990s are poorly dated. In particular, a history of grounding-line retreat is required to understand the relative roles of contemporaneous ocean-forced change and of ongoing glacier response to an earlier perturbation in driving ice-sheet loss. Here we show that the present thinning and retreat of Pine Island Glacier in West Antarctica is part of a climatically forced trend that was triggered in the 1940s. Our conclusions arise from analysis of sediment cores recovered beneath the floating Pine Island Glacier ice shelf, and constrain the date at which the grounding line retreated from a prominent seafloor ridge. We find that incursion of marine water beyond the crest of this ridge, forming an ocean cavity beneath the ice shelf, occurred in 1945 (±12 years); final ungrounding of the ice shelf from the ridge occurred in 1970 (±4 years). The initial opening of this ocean cavity followed a period of strong warming of West Antarctica, associated with El Niño activity. Thus our results suggest that, even when climate forcing weakened, ice-sheet retreat continued.

  16. Stable Delay of Microstrip Line with Side Grounded Conductors

    Directory of Open Access Journals (Sweden)

    T. R. Gazizov

    2017-01-01

    Full Text Available Characteristics of transmission lines are addressed. Wave impedance and per-unit-length delay of the microstrip structure with grounded side conductors on three layers are calculated under different parameters of the structure. A line which provides the desired value of wave impedance and constant per-unit-length delay, at the expense of correction of the gaps on different layers, is proposed.

  17. Post-LGM grounding line and calving front translations of the West Antarctic Ice Sheet in the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica

    Science.gov (United States)

    McGlannan, A. J.; Bart, P. J.; Chow, J.

    2016-12-01

    A large-area (2500 km2) multibeam survey of the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica was acquired during NBP1502B. This sector of the continental shelf is important as it was covered by grounded and floating ice, which drained the central part of an expanded West Antarctic Ice Sheet (WAIS) during the last glacial cycle. The seafloor geomorphology shows a well-defined cluster of four back stepping grounding zone wedges (GZWs) that were deposited in a partly overlapping fashion on the middle continental shelf during WAIS retreat. These observations permit two end-member possibilities for how the WAIS grounding line and calving front vacated the trough. In the first scenario, each GZW represents successive landward shifts of the grounding line and calving front. In the second scenario, each GZW represents a large-scale retreat and re-advance of grounded and floating ice. To determine which of these two end-member scenarios most accurately describes WAIS retreat from this sector of Ross Sea, we evaluated a grid of kasten and piston cores. The core stations were selected on the basis of backstepping GZWs along the trough axis. Our core data analyses included an integration of visual core descriptions, x-ray images, grain size, water content, total organic carbon, shear strengths, and diatom assemblage data. Core data reveal a single transgressive succession from proximal diamict overlain by sub-ice-shelf and/or open-marine sediments. These data strongly support the first scenario, suggesting that an ice shelf remained continuously intact during the time that the grounding line successively moved from the shelf edge to the middle shelf by small-scale landward translations until the end of the fourth grounding event. Sedimentologic and diatom-assemblage data from the inner shelf show that only the last middle shelf grounding event ended with a long-distance retreat of grounded and then floating ice to south of the modern calving front.

  18. AMS Ground Truth Measurements: Calibration and Test Lines

    Energy Technology Data Exchange (ETDEWEB)

    Wasiolek, P. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States)

    2013-11-01

    Airborne gamma spectrometry is one of the primary techniques used to define the extent of ground contamination after a radiological incident. Its usefulness was demonstrated extensively during the response to the Fukushima nuclear power plant (NPP) accident in March-May 2011. To map ground contamination a set of scintillation detectors is mounted on an airborne platform (airplane or helicopter) and flown over contaminated areas. The acquisition system collects spectral information together with the aircraft position and altitude every second. To provide useful information to decision makers, the count rate data expressed in counts per second (cps) needs to be converted to the terrestrial component of the exposure rate 1 m above ground, or surface activity of isotopes of concern. This is done using conversion coefficients derived from calibration flights. During a large scale radiological event, multiple flights may be necessary and may require use of assets from different agencies. However, as the production of a single, consistent map product depicting the ground contamination is the primary goal, it is critical to establish very early into the event a common calibration line. Such a line should be flown periodically in order to normalize data collected from different aerial acquisition systems and potentially flown at different flight altitudes and speeds. In order to verify and validate individual aerial systems, the calibration line needs to be characterized in terms of ground truth measurements. This is especially important if the contamination is due to short-lived radionuclides. The process of establishing such a line, as well as necessary ground truth measurements, is described in this document.

  19. Comb-Line Filter with Coupling Capacitor in Ground Plane

    Directory of Open Access Journals (Sweden)

    Toshiaki Kitamura

    2011-01-01

    Full Text Available A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

  20. Fast retreat of Zachariæ Isstrøm, northeast Greenland.

    Science.gov (United States)

    Mouginot, J; Rignot, E; Scheuchl, B; Fenty, I; Khazendar, A; Morlighem, M; Buzzi, A; Paden, J

    2015-12-11

    After 8 years of decay of its ice shelf, Zachariæ Isstrøm, a major glacier of northeast Greenland that holds a 0.5-meter sea-level rise equivalent, entered a phase of accelerated retreat in fall 2012. The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. Its equal-ice-volume neighbor, Nioghalvfjerdsfjorden, is also melting rapidly but retreating slowly along an upward-sloping bed. The destabilization of this marine-based sector will increase sea-level rise from the Greenland Ice Sheet for decades to come.

  1. Geometric Calibration of ZIYUAN-3 Three-Line Cameras Combining Ground Control Points and Lines

    Science.gov (United States)

    Cao, Jinshan; Yuan, Xiuxiao; Gong, Jianya

    2016-06-01

    Due to the large biases between the laboratory-calibrated values of the orientation parameters and their in-orbit true values, the initial direct georeferencing accuracy of the Ziyuan-3 (ZY-3) three-line camera (TLC) images can only reach the kilometre level. In this paper, a point-based geometric calibration model of the ZY-3 TLCs is firstly established by using the collinearity constraint, and then a line-based geometric calibration model is established by using the coplanarity constraint. With the help of both the point-based and the line-based models, a feasible in-orbit geometric calibration approach for the ZY-3 TLCs combining ground control points (GCPs) and ground control lines (GCLs) is presented. Experimental results show that like GCPs, GCLs can also provide effective ground control information for the geometric calibration of the ZY-3 TLCs. The calibration accuracy of the look angles of charge-coupled device (CCD) detectors achieved by using the presented approach reached up to about 1.0''. After the geometric calibration, the direct georeferencing accuracy of the ZY-3 TLC images without ground controls was significantly improved from the kilometre level to better than 11 m in planimetry and 9 m in height. A more satisfactory georeferencing accuracy of better than 3.5 m in planimetry and 3.0 m in height was achieved after the block adjustment with four GCPs.

  2. Decreasing costs of ground data processing system development using a software product line

    Science.gov (United States)

    Chaffin, Brian

    2005-01-01

    In this paper, I describe software product lines and why a Ground Data Processing System should use one. I also describe how to develop a software product line, using examples from an imaginary Ground Data Processing System.

  3. West Antarctic Ice Sheet Grounding-Line Positions in the Whales Deep Paleo-Ice-Stream Trough of Eastern Ross Sea Inferred From New Multibeam bBathymetry and Seismic Stratigraphy

    Science.gov (United States)

    Bart, P. J.; DeCesare, M.; McGlannan, A. J.; Krogmeier, B.; Danielson, M.

    2016-12-01

    Regional dip-oriented seismic lines and a large-area (2500 km2) multibeam bathymetric survey were acquired during expedition NBP1502B in the Whales Deep paleo-ice-stream trough of eastern Ross Sea. This outer-shelf trough is the downstream continuation of the Bindschadler Ice Stream. The new data provide a more detailed 3D view of the time-transgressive erosional and depositional seafloor features formed during West Antarctic Ice Sheet (WAIS) advance and retreat than was possible to reconstruct with previous reconnaissance-level multibeam and seismic data. The multibeam survey also provides the opportunity to conduct a more detailed analysis of core sedimentology and stratigraphy (McGlannan et al.) that can ultimately be used to investigate grounding-event chronology (DeCesare et al.). The geophysical data show that the WAIS occupied at least four grounding-line positions as it retreated 40 km from the shelf edge to the middle shelf. After the fourth grounding event at the middle shelf, grounded ice retreated abruptly by >200 km to an area/zone south of the modern calving front - where it may have pinned at Roosevelt Island.

  4. First-line anti-tubercular drug resistance of mycobacterial strains from re-treatment cases that were smear-positive at 4th month onwards under the Revised National Tuberculosis Control Program

    OpenAIRE

    Surajit Lahiri; Abhijit Mukherjee; Supabitra Hazra; Pulak Jana; Sandip Roy; Brojo Kishore Saha

    2015-01-01

    Background: Programmatic management of drug-resistant TB (PMDT) under the RNTCP is being implemented in West Bengal in a phased manner since 2011. During the initial years MDR-TB cases were identified based on criteria A. This study examines the first line anti-tubercular drug resistance pattern of mycobacteria cultured from sputum samples of MDR suspects who were retreatment cases smear positive from 4 th month onwards. Materials and Methods: In the following retrospective record based study...

  5. Ocean forcing drives glacier retreat sometimes

    Science.gov (United States)

    Bassis, J. N.; Ultee, E.; Ma, Y.

    2015-12-01

    Observations show that marine-terminating glaciers respond to climate forcing nonlinearly, with periods of slow or negligible glacier advance punctuated by abrupt, rapid retreat. Once glacier retreat has initiated, glaciers can quickly stabilize with a new terminus position. Alternatively, retreat can be sustained for decades (or longer), as is the case for Columbia Glacier, Alaska where retreat initiated ~1984 and continues to this day. Surprisingly, patterns of glacier retreat show ambiguous or even contradictory correlations with atmospheric temperature and glacier surface mass balance. Despite these puzzles, observations increasingly show that intrusion of warm subsurface ocean water into fjords can lead to glacier erosion rates that can account for a substantial portion of the total mass lost from glaciers. Here we use a simplified flowline model to show that even relatively modest submarine melt rates (~100 m/a) near the terminus of grounded glaciers can trigger large increases in iceberg calving leading to rapid glacier retreat. However, the strength of the coupling between submarine melt and calving is a strong function of the geometry of the glacier (bed topography, ice thickness and glacier width). This can lead to irreversible retreat when the terminus is thick and grounded deeply beneath sea level or result in little change when the glacier is relatively thin, grounded in shallow water or pinned in a narrow fjord. Because of the strong dependence on glacier geometry, small perturbations in submarine melting can trigger glaciers in their most advanced—and geometrically precarious—state to undergo sudden retreat followed by much slower re-advance. Although many details remain speculative, our model hints that some glaciers are more sensitive than others to ocean forcing and that some of the nonlinearities of glacier response to climate change may be attributable to variations in difficult-to-detect subsurface water temperatures that need to be better

  6. Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica.

    Science.gov (United States)

    Rebesco, M; Domack, E; Zgur, F; Lavoie, C; Leventer, A; Brachfeld, S; Willmott, V; Halverson, G; Truffer, M; Scambos, T; Smith, J; Pettit, E

    2014-09-12

    Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf.

  7. Evaluation of Fibre Lifetime in Optical Ground Wire Transmission Lines

    Science.gov (United States)

    Grunvalds, R.; Ciekurs, A.; Porins, J.; Supe, A.

    2017-06-01

    In the research, measurements of polarisation mode dispersion of two OPGWs (optical ground wire transmission lines), in total four fibres, have been carried out, and the expected lifetime of the infrastructure has been assessed on the basis of these measurements. The cables under consideration were installed in 1995 and 2011, respectively. Measurements have shown that polarisation mode dispersion values for cable installed in 1995 are four times higher than that for cable installed in 2011, which could mainly be explained by technological differences in fibre production and lower fibre polarisation mode dispersion requirements in 1995 due to lack of high-speed (over 10 Gbit/s) optical transmission systems. The calculation methodology of non-refusal work and refusal probabilities, using the measured polarisation mode dispersion parameters, is proposed in the paper. Based on reliability calculations, the expected lifetime is then predicted, showing that all measured fibres most likely will be operational within minimum theoretical service life of 25 years accepted by the industry.

  8. Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

    Science.gov (United States)

    Halberstadt, Anna Ruth W.; Simkins, Lauren M.; Greenwood, Sarah L.; Anderson, John B.

    2016-05-01

    Studying the history of ice-sheet behaviour in the Ross Sea, Antarctica's largest drainage basin can improve our understanding of patterns and controls on marine-based ice-sheet dynamics and provide constraints for numerical ice-sheet models. Newly collected high-resolution multibeam bathymetry data, combined with two decades of legacy multibeam and seismic data, are used to map glacial landforms and reconstruct palaeo ice-sheet drainage. During the Last Glacial Maximum, grounded ice reached the continental shelf edge in the eastern but not western Ross Sea. Recessional geomorphic features in the western Ross Sea indicate virtually continuous back-stepping of the ice-sheet grounding line. In the eastern Ross Sea, well-preserved linear features and a lack of small-scale recessional landforms signify rapid lift-off of grounded ice from the bed. Physiography exerted a first-order control on regional ice behaviour, while sea floor geology played an important subsidiary role. Previously published deglacial scenarios for Ross Sea are based on low-spatial-resolution marine data or terrestrial observations; however, this study uses high-resolution basin-wide geomorphology to constrain grounding-line retreat on the continental shelf. Our analysis of retreat patterns suggests that (1) retreat from the western Ross Sea was complex due to strong physiographic controls on ice-sheet drainage; (2) retreat was asynchronous across the Ross Sea and between troughs; (3) the eastern Ross Sea largely deglaciated prior to the western Ross Sea following the formation of a large grounding-line embayment over Whales Deep; and (4) our glacial geomorphic reconstruction converges with recent numerical models that call for significant and complex East Antarctic ice sheet and West Antarctic ice sheet contributions to the ice flow in the Ross Sea.

  9. A Comparative Parametric Analysis of the Ground Fault Current Distribution on Overhead Transmission Lines

    OpenAIRE

    VINTAN, M.

    2016-01-01

    The ground fault current distribution in an effectively grounded power network is affected by various factors, such as: tower footing impedances, spans lengths, configuration and parameters of overhead ground wires and power conductors, soil resistivity etc. In this paper, we comparatively analyze, using different models, the ground fault current distribution in a single circuit transmission line with one ground wire. A parametric comparative analysis was done in order to stud...

  10. Modeling Antarctic Ice Sheet retreat in warm climates: a historical perspective.

    Science.gov (United States)

    Pollard, D.; Deconto, R. M.; Gasson, E.

    2016-12-01

    Early modeling of Antarctic Ice Sheet size vs. climate focused on asymmetry between retreat and growth, with much greater warming needed to cause retreat from full ice cover, due to Height Mass Balance Feedback and albedo feedback. This led to a long-standing model-data conflict, with models needing 1000 to2000 ppmv atmospheric CO2 to produce retreat from full size, vs. proxy data of large ice fluctuations despite much lower CO2 since the Miocene.Subsequent modeling with marine ice physics found that the West Antarctic Ice Sheet could undergo repeated warm-period collapses with realistic past forcing. However, that yields only 3 to 7 m equivalent sea-level rise above modern, compared to 10 to 20 m or more suggested by some geologic data. Large subglacial basins in East Antarctica could be vulnerable to the same processes,but did not retreat in most models due to narrower and shallower sills.After recent modifications, some ice sheet models were able to produce warm-period collapse of major East Antarctic basins, with sea-level rise of up to 15 m. The modifications are (i) hydrofracturing by surface melt, and structural failure of ice cliffs, or (ii) numerical treatment at the grounding line. In these models, large retreat occurs both for past warmintervals, and also for future business-as-usual scenarios.Some interpretations of data in the late Oligocene and Miocene suggest yet larger fluctuations, between 50 to 100% of modern Antarctic size. That would require surface-melt driven retreat of some terrestrial East Antarctic ice, despite the hysteresis issue raised above. A recent study using a coupled climate-ice sheet model found that with a finer climate gridand more frequent coupling exchange, substantial retreat of terrestrial Antarctica can occur with 500 to 840 ppmv CO2, much lower than in earlier models. This will allow meaningful interactions between modeling and deeper-time geologic interpretations since the late Oligocene.

  11. First-line anti-tubercular drug resistance of mycobacterial strains from re-treatment cases that were smear-positive at 4 th month onwards under the Revised National Tuberculosis Control Program

    Directory of Open Access Journals (Sweden)

    Surajit Lahiri

    2015-01-01

    Full Text Available Background: Programmatic management of drug-resistant TB (PMDT under the RNTCP is being implemented in West Bengal in a phased manner since 2011. During the initial years MDR-TB cases were identified based on criteria A. This study examines the first line anti-tubercular drug resistance pattern of mycobacteria cultured from sputum samples of MDR suspects who were retreatment cases smear positive from 4 th month onwards. Materials and Methods: In the following retrospective record based study, data on Drug Sensitivity Testing (DST of sputum samples of MDR suspects between September 2011 and August 2012 were collected from the IRL Kolkata and analysed. Sputum samples, collected in the districts maintaining adequate aseptic containment measures, were decontaminated and centrifuged and the sediment inoculated on LJ medium. Probable M. tuberculosis colonies were identified by typical colony characteristics and Ziehl-Neelsen (ZN staining. Sensitivity of the four 1 st line drugs (Streptomycin, Isoniazid, Ethambutol and Rifampicin was deduced by the economic variant of the proportion method. Results: Of all the 917 MDR suspects whose sputum was examined, 64 mycobacteria culture positive strains (6.98% were mono-resistant to any of the four first line anti-tubercular drugs. Among the mono-resistant strains 43 (4.69% were resistant to Rifampicin while 12 (1.31% were resistant to INH. There were a total 78 (8.51% poly drug-resistant strains. MDR-TB strains were seen in 741 (80.81% samples. Conclusion: The magnitude of drug resistance were very high among retreatment patients that were smear positive from 4 th months onwards probably because of repeated courses of anti-tubercular drugs prior to drug sensitivity testing (DST. The decision of the PMDT to enlist all retreatment patients as MDR suspects at initiation will result in early identification and treatment of MDR-TB patients.

  12. Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion.

    Science.gov (United States)

    Aitken, A R A; Roberts, J L; van Ommen, T D; Young, D A; Golledge, N R; Greenbaum, J S; Blankenship, D D; Siegert, M J

    2016-05-19

    Climate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion-enough to expose basement rocks-has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today's grounding line; and deep within the Sabrina Subglacial Basin, 350-550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the 'modern-scale' ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200-250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat-advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration.

  13. Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion

    Science.gov (United States)

    Aitken, A. R. A.; Roberts, J. L.; Ommen, T. D. Van; Young, D. A.; Golledge, N. R.; Greenbaum, J. S.; Blankenship, D. D.; Siegert, M. J.

    2016-05-01

    Climate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion—enough to expose basement rocks—has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today’s grounding line; and deep within the Sabrina Subglacial Basin, 350-550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the ‘modern-scale’ ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200-250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat-advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration.

  14. Simulating LGM retreat of the Uummannaq Ice Stream and Rinks Isbrae, Western Greenland using a 1-D ice-stream model constrained by a suite of marine and terrestrial data

    Science.gov (United States)

    Jamieson, Stewart; Roberts, Dave; Rea, Brice; Lane, Timothy; Vieli, Andreas; Cofaigh, Colm Ó.

    2014-05-01

    We aim to understand what controlled the retreat pattern of the Uummannaq Ice Stream (UIS) during the last deglaciation. Evidence for the pattern of retreat is found in both the marine and terrestrial realms, but because the evidence is temporally and spatially discontinuous, it is challenging to coherently reconstruct both grounding-line retreat and ice-surface thinning such that they are in agreement. Marine stratigraphic and geophysical evidence indicates that the ice stream was grounded close to the continental shelf edge at the Last Glacial Maximum, and retreated rapidly and nonlinearly after 14.8 ka. Cosmogenic nuclide exposure dating on Ubekendt Island at the convergence zone of multiple feeder ice streams show that the ice surface thinned progressively and that the island became ice-free by ca. 12.4 ka. The ice stream then collapsed over the next 1-1.6 kyrs and the ice stream separated into a series of distinct inland arms. In the northernmost Rinks system, there is a 'staircase' of evidence showing ice surface thinning over time, but it is unclear where the grounding line was located during this phase of thinning. Furthermore, it is currently unclear what controlled the nonlinear retreat pattern identified in the Uummannaq system. We develop a numerical model of ice-stream retreat using the marine geophysical data and measurements of sediment strength on the continental shelf to control the boundary conditions. The model has the capability to dynamically and robustly simulate grounding line-retreat behaviour over millennial timescales. We simulate the retreat of the UIS grounding line into the northernmost Rinks system in response to enhanced ocean warming, rising sea level and warming climate. We compare the simulated dynamic behaviour of the UIS against the geomorphological and cosmogenic exposure evidence for ice surface thinning onshore and against dated marine grounding line positions. Our model results enable us to match grounding-line positions in

  15. Pliocene retreat of Greenland and Antarctic Ice Sheet margins (Invited)

    Science.gov (United States)

    Deconto, R. M.; Pollard, D.

    2013-12-01

    The middle Pliocene epoch (~3 million years ago) is often considered an analogue for future global climatic conditions, because global mean temperatures were comparable to projections of future climate at the end of this century. Importantly, some estimates of mid-Pliocene sea level are >20 m higher than today, implying the potential for significant retreat of the East Antarctic Ice Sheet (EAIS), in addition to the loss of the Greenland and West Antarctic Ice Sheets (WAIS). Here, we use a hybrid ice sheet-shelf model with freely migrating grounding lines coupled to a high-resolution regional climate model to test the potential for both West and East Antarctic Ice Sheet retreat during the warm Pliocene and in long-term future scenarios with elevated CO2. In these simulations we apply new treatments of i) ice shelf calving (accounting for the effects of divergent ice flow and surface melt water on crevassing), ii) ice-cliff mechanics at the grounding line, iii) improved sub-glacial bathymetry using BEDMAP2, and iv) a range of plausible ocean warming scenarios based on offline ocean modeling. In warm Pliocene simulations, the combination of improved bathymetric detail and more physically based model treatments of floating and grounded calving fronts substantially increases the rates and magnitudes of ice sheet retreat into over-deepened subglacial basins in both in West and East Antarctica. These new results imply the EAIS margin did indeed contribute to elevated (and orbitally paced) Pliocene sea levels, with Antarctica contributing up to ~20m equivalent sea level during the warmest intervals. In long-term (10^3-4-yr) future simulations using the same model physics, we find these new mechanisms produce a much more sensitive and vulnerable ice sheet than previously considered, with the potential for substantial future retreat of both WAIS and parts of the East Antarctic margin in response to the combined effects of increased surface melt on ice shelf surfaces and

  16. A Comparative Parametric Analysis of the Ground Fault Current Distribution on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    VINTAN, M.

    2016-02-01

    Full Text Available The ground fault current distribution in an effectively grounded power network is affected by various factors, such as: tower footing impedances, spans lengths, configuration and parameters of overhead ground wires and power conductors, soil resistivity etc. In this paper, we comparatively analyze, using different models, the ground fault current distribution in a single circuit transmission line with one ground wire. A parametric comparative analysis was done in order to study the effects of the non-uniformity of the towers footing impedances, number of power lines spans, soil resistivity, grounding systems resistances of the terminal substations etc., on the ground fault current distribution. There are presented some useful qualitative and quantitative results obtained through a complex dedicated developed MATLAB 7.0 program.

  17. Murdoch Retreats from China

    Institute of Scientific and Technical Information of China (English)

    Jessy Zhang

    2006-01-01

    @@ News Corp's Asian flagship enterprise Star Group announced in early June it would sell a 19.9 percent stake in Phoenix Satellite Television to China Mobile. This move is widely interpreted as a signal that Rudolf Murdoch, the helmsman of News Corp,might have lost his patience and could eventually retreat from the Chinese media market.

  18. Coupling Between Microstrip Lines and Finite Ground Coplanar Lines Embedded in Polyimide Layers for 3D-MMICs on Silicon

    Science.gov (United States)

    Ponchak, G. E.; Bushyager, N.; Papapolymerou, J.; Tentzeris, E. M.; Laskar, J.

    2002-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/mm-wave integrated circuits on CMOS (low resistivity) Si wafers. It is expected that these circuits will replace the ones fabricated on GaAs and reduce the overall system cost. However, the closely spaced transmission lines that are required for a high-density circuit environment are susceptible to high levels of cross-coupling, which degrades the overall circuit performance. In this paper, theoretical and experimental results on coupling and ways to reduce it are presented for two types of transmission lines: a) the microstrip line and b) the Finite Ground Coplanar (FGC) line. For microstrip lines it is shown that a fence of metalized via-holes can significantly reduce coupling, especially in the case when both lines are on the same polyimide layer or when the shielding structure extends through several polyimide layers. For closely spaced microstrip lines, coupling is lower for a metal filled trench shield than a via-hole fence. Coupling amongst microstrip lines is dependent on the ratio of line separation to polyimide thickness and is primarily due to magnetic fields. For FGC lines it is shown that they have in general low coupling that can be reduced significantly when there is even a small gap between the ground planes of each line. FGC lines have approximately 8 dB lower coupling than coupled coplanar waveguides (CPW). In addition, forward and backward characteristics of the FGC lines do not resemble those of other transmission lines such as microstrip. Therefore, the coupling mechanism of the FGC lines is different compared to thin film microstrip lines.

  19. Bathymetric Controls On Observed Tidewater Glacier Retreat In Northwest Greenland

    Science.gov (United States)

    Porter, D. F.; Tinto, K. J.; Boghosian, A.; Cochran, J. R.; Bell, R. E.

    2013-12-01

    Although many of the largest glaciers in Greenland are losing mass, the large variability in observed mass wastage of the remaining glaciers clouds interpretation of the proposed external forcings, such as warming of the ocean or atmosphere. Some glaciers are accelerating and thinning while other nearby glaciers advance and gain mass. Recent efforts suggest that increased ocean temperatures may be responsible for the observed glacial retreat in Greenland and Antarctica through increased basal melting beneath floating ice tongues and vertical ice faces of tidewater glaciers. Basal melting may contribute significantly to calving and thinning, and to an eventual speeding up of the glacier, resulting in thinning further inland. Knowledge of fjord geometry is crucial for ice-ocean interaction because the availability of ocean heat to the ice will be restricted by narrow sills and shallow grounding lines. We investigate whether the variability in observed changes among Greenland glaciers can be partially explained by variation in fjord geometry. Some features of a fjord that could influence the ice-ocean system include the depth of the grounding line, the presence of sills, sloping bed, and the water cavity shape beneath floating ice. New estimates of fjord bathymetries in northwest Greenland, using airborne gravimetry measurements from NASA Operation IceBridge flights, are compared to estimates of ice acceleration and mass wastage of neighboring glaciers. We investigate the correlation between fjord geometry features and several glacier parameters, such as surface velocity and elevation changes. We determine that the geometry of glacial fjords play a large role in determining the stability of outlet glaciers. Deep sills and deep terminus grounding lines will allow greater interaction with the deep and warm Atlantic water off the shelf break. For two neighboring glaciers in northwest Greenland, we find that the glacier with a deeper grounding line, and presumably in

  20. Structural responses of secondary lining of high-speed railway tunnel excavated in loess ground

    OpenAIRE

    Zhang, Dingli; Fang, Qian; Li, Pengfei; Wong, Louis

    2013-01-01

    To systematically study the mechanical properties and structural responses of the secondary lining for high-speed railway tunnels excavated in loess ground, on-site monitoring was performed to measure the contact pressure between the primary lining and secondary lining. It is found that the contact pressure reaches its first peak value when the tunnel formwork carriage is removed. The load acting on secondary lining is in the form of deformation pressure, which is different from the loose pre...

  1. Detection of Rockfall on a Tunnel Concrete Lining with Ground-Penetrating Radar (GPR)

    Science.gov (United States)

    Lalagüe, Anne; Lebens, Matthew A.; Hoff, Inge; Grøv, Eivind

    2016-07-01

    Experiments were conducted using Ground-Penetrating Radar (GPR). The performance of six GPR systems was assessed in terms of: (1) remotely mapping cavities behind concrete linings, (2) detecting rockfall from the tunnel roof onto an inner lining comprising, for example, precast concrete segments. Studies conducted in Norway and the United States demonstrate that the GPR technique is a simple and reliable method that can assist stability inspection in existing Norwegian tunnels. The ground-coupled GPR systems represent a step forward in the remote detection of rockfall on tunnel concrete linings, and are particularly suited to self-standing inner linings. The analysis of the data is relatively straightforward and reasonably accurate.

  2. The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets

    OpenAIRE

    Cooper, Scott T.; Richters, Karl E.; Melin, Travis E.; Liu, Zhi-Jian; Hordyk, Peter J.; Benrud, Ryan R.; Geiser, Lauren R.; Cash, Steve E.; Simon Shelley, C.; Howard, David R.; Ereth, Mark H.; Sola-Visner, Martha C.

    2012-01-01

    Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4–8°C and 3–5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4–8°C wer...

  3. Ocean forcing of Ice Sheet retreat in central west Greenland from LGM to the early Holocene

    Science.gov (United States)

    Jennings, Anne E.; Andrews, John T.; Ó Cofaigh, Colm; Onge, Guillaume St.; Sheldon, Christina; Belt, Simon T.; Cabedo-Sanz, Patricia; Hillaire-Marcel, Claude

    2017-08-01

    Three radiocarbon dated sediment cores from trough mouth fans on the central west Greenland continental slope were studied to determine the timing and processes of Greenland Ice Sheet (GIS) retreat from the shelf edge during the last deglaciation and to test the role of ocean forcing (i.e. warm ocean water) thereon. Analyses of lithofacies, quantitative x-ray diffraction mineralogy, benthic foraminiferal assemblages, the sea-ice biomarker IP25, and δ18 O of the planktonic foraminifera Neogloboquadrina pachyderma sinistral from sediments in the interval from 17.5-10.8 cal ka BP provide consistent evidence for ocean and ice sheet interactions during central west Greenland (CWG) deglaciation. The Disko and Uummannaq ice streams both retreated from the shelf edge after the last glacial maximum (LGM) under the influence of subsurface, warm Atlantic Water. The warm subsurface water was limited to depths below the ice stream grounding lines during the LGM, when the GIS terminated as a floating ice shelf in a sea-ice covered Baffin Bay. The deeper Uummannaq ice stream retreated first (ca. 17.1 cal ka BP), while the shallower Disko ice stream retreated at ca. 16.2 cal ka BP. The grounding lines were protected from accelerating mass loss (calving) by a buttressing ice shelf and by landward shallowing bathymetry on the outer shelf. Calving retreat was delayed until ca. 15.3 cal ka BP in the Uummannaq Trough and until 15.1 cal ka BP in the Disko Trough, during another interval of ocean warming. Instabilities in the Laurentide, Innuitian and Greenland ice sheets with outlets draining into northern Baffin Bay periodically released cold, fresh water that enhanced sea ice formation and slowed GIS melt. During the Younger Dryas, the CWG records document strong cooling, lack of GIS meltwater, and an increase in iceberg rafted material from northern Baffin Bay. The ice sheet remained in the cross-shelf troughs until the early Holocene, when it retreated rapidly by calving and strong

  4. Ground-Wave Propagation Effects on Transmission Lines through Error Images

    Directory of Open Access Journals (Sweden)

    Uribe-Campos Felipe Alejandro

    2014-07-01

    Full Text Available Electromagnetic transient calculation of overhead transmission lines is strongly influenced by the natural resistivity of the ground. This varies from 1-10K (Ω·m depending on several media factors and on the physical composition of the ground. The accuracy on the calculation of a system transient response depends in part in the ground return model, which should consider the line geometry, the electrical resistivity and the frequency dependence of the power source. Up to date, there are only a few reports on the specialized literature about analyzing the effects produced by the presence of an imperfectly conducting ground of transmission lines in a transient state. A broad range analysis of three of the most often used ground-return models for calculating electromagnetic transients of overhead transmission lines is performed in this paper. The behavior of modal propagation in ground is analyzed here into effects of first and second order. Finally, a numerical tool based on relative error images is proposed in this paper as an aid for the analyst engineer to estimate the incurred error by using approximate ground-return models when calculating transients of overhead transmission lines.

  5. Development Ground Fault Detecting System for D.C Voltage Line

    Energy Technology Data Exchange (ETDEWEB)

    Kim Taek Soo; Song Ung Il; Gwon, Young Dong; Lee Hyoung Kee [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1996-12-31

    It is necessary to keep the security of reliability and to maximize the efficiency of maintenance by prompt detection of a D.C feeder ground fault point at the built ed or a building power plants. At present, the most of the power plants are set up the ground fault indicator lamp in the monitor room. If a ground fault occurs on DC voltage feeder, a current through the ground fault relay is adjusted and the lamps have brightened while the current flows the relay coil. In order to develop such a system, it is analyzed a D.C feeder ground circuit theoretically and studied a principles which can determine ground fault point or a polarity discrimination and a phase discrimination of the line. So, the developed system through this principles can compute a resistance ground fault current and a capacitive ground fault current. It shows that the system can defect a ground fault point or a bad insulated line by measuring a power plant D.C feeder insulation resistance at the un interruptible power status, and therefore the power plant could protect an unexpected service interruption . (author). 18 refs., figs.

  6. Experimental study on sliding shaft lining mechanical mechanisms under ground subsidence conditions

    Institute of Scientific and Technical Information of China (English)

    姚直书; 杨俊杰; 孙文若

    2003-01-01

    Aimed at more than 60 shaft linings damaged in Huaibei, Datun, Xuzhou and Yanzhou mine areas, this paper presents a new type of sliding shaft lining with asphalt blocks sliding layer. By model test, it is obtained that the deformation characteristics and the mechanical mechanisms of the sliding shaft lining under the condition of ground subsidence. The research results provide a testing basis for the sliding shaft lining design. By now, this kind of sliding shaft lining had been applied in 9 shafts in China and Bangladesh.

  7. Modeling Drastic Ice Retreat in Antarctic Subglacial Basins

    Science.gov (United States)

    Pollard, D.; Deconto, R. M.

    2013-12-01

    Various data indicate that global mean sea level has fluctuated on O(10,000 to 100,000) year time scales during the last ~25 million years, reaching 20 m or more above modern. If correct, this implies substantial variations in the size of the East Antarctic Ice Sheet (EAIS). However, climate and ice-sheet models have not been able to simulate significant EAIS retreat from continental size, given low proxy atmospheric CO2 levels during this time. Here, we use a new mechanism involving a maximum vertical ice cliff size of ~100 m above the ocean at the grounding line beyond which structural failure occurs, triggered by the complete melting of floating shelves that normally prevent this configuration in large embayments. This is tested in a 3-D ice-sheet model by applying oceanic and climatic warming representing past warm periods, which attacks floating ice shelves by basal melting and by increased calving due to surface melt or rain draining into crevasses. In addition to accelerating the expected collapse of West Antarctic ice, the new mechanisms cause drastic retreat into 3 major East Antarctic subglacial basins, causing ~20 m global sea-level rise within a few thousand years that takes more than 10,000 years to recover. This offers a resolution of the past sea level model-data conflict, but suggests that Antarctica may be more vulnerable to future warming than previously realized.

  8. Influence of damage and basal friction on the grounding line dynamics

    Science.gov (United States)

    Brondex, Julien; Gagliardini, Olivier; Gillet-Chaulet, Fabien; Durand, Gael

    2016-04-01

    The understanding of grounding line dynamics is a major issue in the prediction of future sea level rise due to ice released from polar ice sheets into the ocean. This dynamics is complex and significantly affected by several physical processes not always adequately accounted for in current ice flow models. Among those processes, our study focuses on ice damage and evolving basal friction conditions. Softening of the ice due to damaging processes is known to have a strong impact on its rheology by reducing its viscosity and therefore promoting flow acceleration. Damage creates where shear stresses are high enough which is usually the case at shear margins and in the vicinity of pinning points in contact with ice-shelves. Those areas are known to have a buttressing effect on ice shelves contributing to stabilize the grounding line. We aim at evaluating the extent to which this stabilizing effect is hampered by damaging processes. Several friction laws have been proposed by various author to model the contact between grounded-ice and bedrock. Among them, Coulomb-type friction laws enable to account for reduced friction related to low effective pressure (the ice pressure minus the water pressure). Combining such a friction law to a parametrization of the effective pressure accounting for the fact that the area upstream the grounded line is connected to the ocean, is expected to have a significant impact on the grounding line dynamics. Using the finite-element code Elmer/Ice within which both the Coulomb-type friction law, the effective pressure parametrization and the damage model have been implemented, the goal of this study is to investigate the sensitivity of the grounding line dynamics to damage and to an evolving basal friction. The relative importance between those two processes on the grounding line dynamics is addressed as well.

  9. Polar Cap Retreat

    Science.gov (United States)

    2004-01-01

    13 August 2004 This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of the retreating seasonal south polar cap in the most recent spring in late 2003. Bright areas are covered with frost, dark areas are those from which the solid carbon dioxide has sublimed away. The center of this image is located near 76.5oS, 28.2oW. The scene is large; it covers an area about 250 km (155 mi) across. The scene is illuminated by sunlight from the upper left.

  10. Grounding line variability and subglacial lake drainage on Pine Island Glacier, Antarctica

    Science.gov (United States)

    Joughin, Ian; Shean, David E.; Smith, Ben E.; Dutrieux, P.

    2016-09-01

    We produced a 6 year time series of differential tidal displacement for Pine Island Ice Shelf, Antarctica, using speckle-tracking methods applied to fine-resolution TerraSAR-X data. These results reveal that the main grounding line has maintained a relatively steady position over the last 6 years, following the speedup that terminated in ~2009. In the middle of the shelf, there are grounded spots that migrate downstream over the 6 year record. Examination of high-resolution digital elevation models reveals that these grounded spots form where deep keels (thickness anomalies) advect over an approximately flow-parallel bathymetric high, maintaining intermittent contact with the bed. These data sets also reveal several subsidence and uplift events associated with subglacial lake drainages in the fast-flowing region above the grounding line. Although these drainages approximately double the rate of subglacial water flow over periods of a few weeks, they have no discernible effect on horizontal flow speed.

  11. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line.

    Science.gov (United States)

    Drews, R; Pattyn, F; Hewitt, I J; Ng, F S L; Berger, S; Matsuoka, K; Helm, V; Bergeot, N; Favier, L; Neckel, N

    2017-05-09

    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  12. Coupling Between Microstrip Lines With Finite Width Ground Plane Embedded in Thin Film Circuits

    Science.gov (United States)

    Ponchak, George E.; Dalton, Edan; Tentzeris, Manos M.; Papapolymerou, John

    2003-01-01

    Three-dimensional (3D) interconnects built upon multiple layers of polyimide are required for constructing 3D circuits on CMOS (low resistivity) Si wafers, GaAs, and ceramic substrates. Thin film microstrip lines (TFMS) with finite width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS lines a r e susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and experimental measurements a r e used to show that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions. Furthermore, it is shown that coupled microstrip lines establish a slotline type mode between the two ground planes and a dielectric waveguide type mode, and that the via holes recommended here eliminate these two modes.

  13. IMPROVING SOLUTIONS OF EQUIPMENT’S RELIABILITY FOR DETECTION OF GROUNDING LINES

    Directory of Open Access Journals (Sweden)

    PĂCUREANU I.

    2015-12-01

    Full Text Available The paper has three parts, in the first one, is presented the theoretical concepts that refer on the grounding lines fault, the treating mode, and implemented solutions for their detection in electric stations. In the second part is presented the result of the operational reliability analyse in period of 2011 – 2015, as in the final part of the paper are given the conclusions and identified solutions regarding the improving of operational reliability of the protection equipment of detection of grounding lines.

  14. ProTaper机用锉行后牙根管再治疗时的护理研究%Nursing Research ProTaper Rotary File Line after Root Canal Re-treatment

    Institute of Scientific and Technical Information of China (English)

    邹亚清; 张建珍; 于玲; 吴云暖

    2016-01-01

    目的:分析ProTaper机用锉行后牙根管再治疗期间护理干预的方法与应用价值。方法方便选取2013年1月—2016年1月期间该院收治的80例ProTaper机用锉行后牙根管再治疗患者作为研究对象,按照数字随机表方法进行分组,对照组、观察组中分别纳入40例患者。对照组患者实施常规护理,观察组患者实施术前、术中、术后全方位护理配合。对比观察两组患者在不同护理方法干预下根管治疗后疼痛情况以及并发症发生率的差异。结果观察组、对照组患者经ProTaper机用锉行后牙根管再治疗后均成功疏通根管,根管治疗完成后相关症状均明显缓解或完全消失。观察组患者行ProTaper机用锉行后牙根管再治疗期间并发症总发生率为5.00%(2/40),显著低于对照组27.50%(11/40)(P﹤0.05)。观察组患者行ProTaper机用锉行后牙根管再治疗期间急性反应发生率为5.00%(2/40),显著低于对照组25.00%(10/40)(P﹤0.05)。结论在ProTaper机用锉行后牙根管再治疗期间,加强术前、术中、术后全方位护理配合,能够确保患者根管疏通效果,对降低各类并发症发生率以及急性反应发生率均有确切意义。%Objective Analysis and Application Value ProTaper rotary file row during root canal after retreatment nursing interventions. Methods Convenient selection in the period from January 2013 to January 2016 in our hospital 80 cases of ProTaper rotary file line after root canal re-treatment of patients as research subjects, according to the random numbers table method group and control group, the observation group were It included 40 patients. Routine care for patients in the control group, the observation group for patients with preoperative, intraoperative and postoperative care-round cooperation. Comparative intervention were observed as well as differences in the incidence of complications after root canal treatment of pain in

  15. Holocene Glacial Retreat at Walgreen Coast, West Antarctica

    Science.gov (United States)

    Lindow, J.; Johnson, J.; Castex, M.; Wittmann, H.; Smith, J.; Lisker, F.; Gohl, K.; Spiegel, C.

    2012-12-01

    The Walgreen Coast of West Antarctica represents one of the most rapidly changing sectors of the West Antarctic Ice Sheet (WAIS). With the fastest ice streams in the whole Antarctic, the WAIS is characterised by rapid thinning and grounding line retreat. Airborne and satellite-based short-term observations show a doubling of the negative net mass balance between 1996-2006 (Rignot et al., 2008). Furthermore, because the WAIS is largely grounded below sea level, continued inland thinning and grounding line retreat could result in rapid ice sheet collapse, which would raise global sea level by between 3-5 m. However, due to remoteness and challenging accessibility, onshore data is limited to a few isolated nunataks making it difficult to assess the long-term evolution of the glacial dynamics along Walgreen Coast. To address this we present new data from two key areas of the Walgreen Coast; the Kohler Range and the Pine Island Bay. Our 10Be surface exposure ages from erratic boulders in the Kohler Range are the first and reveal that this area became ice-free between 8.3 and 12.3 ka. This implies a long-term thinning rate of 3.3 cm/yr and agrees with similar data published from glaciers eastward. Our ages are also consistent with recent deglaciation models which suggest strong thinning after 15 ka and off-shore sediments shows a concurrent lateral ice-shelf front retreat. Our results suggest an ice-cover at least 300 m thicker in the Kohler Range during the early Holocene and that subsequent average thinning occurred on rates one order of magnitude slower than recent satellite measurements show. This implies that the recent trend in ice-sheet thinning results from a recent dynamic changes rather than a response to long-term thinning. To further constrain the lateral deglaciation history along the eastern Walgreen Coast, namely the Pine Island Glacier, we collected additional samples from a chain of islands, located flow-parallel and downstream of the ice-shelf front. We

  16. On-line, proximate analysis of ground beef directly at a meat grinder outlet.

    Science.gov (United States)

    Isaksson, T; Nilsen, B N; Tøgersen, G; Hammond, R P; Hildrum, K I

    1996-07-01

    The fat, moisture and protein contents of ground beef were determined on-line by a diffuse reflectance near infrared (NIR) spectroscopy instrument at the outlet of a meat grinder. Beef samples in the range of 6.2-21.7% fat, 59.6-72.9% moisture and 18.1-20.7% protein were studied. Calibrations from samples ground with hole diameters of 4, 8, 13 or 19 mm in the grinder plate were validated. In addition, calibrations of combinations of these samples from the different hole diameters were validated. Prediction errors, expressed as root mean square error of cross validation of the beef samples, were 0.73-1.50% for fat, 0.75-1.33% for moisture and 0.23-0.32% for protein, depending on the hole diameter of the grinder plate. Calibrations from samples ground with the smallest hole diameters gave lowest prediction errors. The present prediction error results are only slightly higher compared to reported prediction error results using conventional at- and off-line NIR instruments. It is concluded that the on-line NIR prediction results were acceptable for samples ground with grinder plates of 4, 8 or 13 mm hole diameter.

  17. West Antarctic Ice Sheet retreat from Pine Island Bay during the Holocene: New insights into forcing mechanisms

    Science.gov (United States)

    Hillenbrand, Claus-Dieter; Smith, James; Kuhn, Gerhard; Poole, Chris; Hodell, David; Elderfield, Harry; Kender, Sev; Williams, Mark; Peck, Victoria; Larter, Robert; Klages, Johann; Graham, Alastair; Forwick, Matthias; Gohl, Karsten

    2013-04-01

    The Amundsen Sea sector of the largely marine-based and therefore conditionally unstable West Antarctic Ice Sheet (WAIS) contains enough ice to raise global sea level by ca. 1.5 metres. At present, ice streams draining this sector into the Southern Ocean, especially glaciers flowing into Pine Island Bay in the eastern Amundsen Sea embayment, are undergoing considerable mass loss characterised by major thinning, flow acceleration and rapid grounding-line retreat. Sub-ice shelf melting by relatively warm Circumpolar Deep Water (CDW) upwelling onto the continental shelf is held responsible for these dynamical changes but atmospheric warming in West Antarctica may also have contributed to them. In contrast to the modern situation, the long-term history of the Amundsen Sea sector and the mechanisms forcing its deglaciation during the Holocene are only poorly constrained. We will present new palaeoenvironmenal data obtained from marine sediment cores collected in Pine Island Bay. The cores targeted shallow sites on the inner continental shelf and successfully recovered sedimentary sequences bearing calcareous microfossils. Radiocarbon ages on these microfossils demonstrate that the grounding line of the WAIS retreated to within ~100 km of its modern position before ca. 10 kyr BP (thousand years before present), which is consistent with an early WAIS retreat from near-coastal locations in the western Amundsen Sea embayment. Currently, there is no evidence that the grounding line had retreated landward of its modern position during the Holocene. Therefore, the chronological constraints may imply that during the last 10 kyr any episodes of fast grounding-line retreat similar to those observed today were short-lived and rare. Preliminary geochemical data from benthic and planktonic foraminifera tests in the cores from Pine Island Bay reveals that intense CDW upwelling coincided with and may have forced the deglaciation of the inner continental shelf. Furthermore, we observe

  18. Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration

    Science.gov (United States)

    Goldberg, D. N.; Heimbach, P.; Joughin, I.; Smith, B.

    2015-12-01

    A glacial flow model of Smith, Pope and Kohler Glaciers is calibrated by means of control methods against time varying, annually resolved observations of ice height and velocities, covering the period 2002 to 2011. The inversion - termed "transient calibration" - produces an optimal set of time-mean, spatially varying parameters together with a time-evolving state that accounts for the transient nature of observations and the model dynamics. Serving as an optimal initial condition, the estimated state for 2011 is used, with no additional forcing, for predicting grounded ice volume loss and grounding line retreat over the ensuing 30 years. The transiently calibrated model predicts a near-steady loss of grounded ice volume of approximately 21 km3 a-1 over this period, as well as loss of 33 km2 a-1 grounded area. We contrast this prediction with one obtained following a commonly used "snapshot" or steady-state inversion, which does not consider time dependence and assumes all observations to be contemporaneous. Transient calibration is shown to achieve a better fit with observations of thinning and grounding line retreat histories, and yields a quantitatively different projection with respect to ice volume loss and ungrounding. Sensitivity studies suggest large near-future levels of unforced, i.e., committed sea level contribution from these ice streams under reasonable assumptions regarding uncertainties of the unknown parameters.

  19. Syrtis in Retreat

    Science.gov (United States)

    2003-01-01

    [figure removed for brevity, see original site] Released 30 June 2003Lava flows from the broad shield volcano Syrtis Major have poured into the Isidis Basin to the east. The transition between these great provinces is marked by broken slabs of accumulated volcanic material that is retreating from its position on the floor of the basin. A jagged scarp a half a kilometer high is the result.Image information: VIS instrument. Latitude 13.7, Longitude 79.4 East (280.6 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Characteristic Impedance of a Microstrip-Like Interconnect Line in Presence of Ground Plane Aperture

    Directory of Open Access Journals (Sweden)

    Rohit Sharma

    2007-01-01

    Full Text Available We propose new empirical expressions for the characteristic impedance of a microstrip-like interconnect line in presence of ground plane aperture. The existing characteristic impedance expressions are modified so as to include the effect of the ground plane aperture. The variation in the characteristic impedance vis-à-vis the aperture size is established. The proposed expressions are general and valid for a range of dielectric materials concerning MICs, RFICs, and PCBs. The results are validated by measurements performed on a vector network analyzer.

  1. Single Phase-to-Ground Fault Line Identification and Section Location Method for Non-Effectively Grounded Distribution Systems Based on Signal Injection

    Institute of Scientific and Technical Information of China (English)

    PAN Zhencun; WANG Chengshan; CONG Wei; ZHANG Fan

    2008-01-01

    A diagnostic signal current trace detecting based single phase-to-ground fault line identifica- tion and section location method for non-effectively grounded distribution systems is presented in thisi oaper. A special diagnostic signal current is injected into the fault distribution system, and then it is de- tected at the outlet terminals to identify the fault line and at the sectionalizing or branching point along the fault line to locate the fault section. The method has been put into application in actual distribution network and field experience shows that it can identify the fault line and locate the fault section correctly and effectively.

  2. Analysis of overvoltages in overhead ground wires of extra high voltage (EHV) power transmission line under single-phase-to-ground faults

    NARCIS (Netherlands)

    Dudurych, [No Value; Rosolowski, E

    2000-01-01

    Overhead ground wires (GW) of extra high voltage (EHV) power transmission lines, apart from lightning-induced overvoltage protection are frequently used for carrier-current communication. In this case the ground wires are suspended on insulators, the dielectric strength of which should be sufficient

  3. Fault Line Selection Method Considering Grounding Fault Angle for Distribution Network

    Institute of Scientific and Technical Information of China (English)

    Li Si-bo; Zhao Yu-lin; Li Ji-chang; Sui Tao

    2015-01-01

    In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.

  4. Tips for a Successful Leadership Retreat

    Science.gov (United States)

    Bonstingl, John Jay

    2005-01-01

    This article focuses on planning a retreat for board, leadership team, or community and business partners. The author provides 10 suggestions for effective retreat planning: (1) Plan one's retreat with a clear purpose in mind; (2) Make retreat more relevant; (3) Build on current and past successes; (4) Make sure the right people are invited and…

  5. Seismic Response of Power Transmission Tower-Line System Subjected to Spatially Varying Ground Motions

    Directory of Open Access Journals (Sweden)

    Li Tian

    2010-01-01

    Full Text Available The behavior of power transmission tower-line system subjected to spatially varying base excitations is studied in this paper. The transmission towers are modeled by beam elements while the transmission lines are modeled by cable elements that account for the nonlinear geometry of the cables. The real multistation data from SMART-1 are used to analyze the system response subjected to spatially varying ground motions. The seismic input waves for vertical and horizontal ground motions are also generated based on the Code for Design of Seismic of Electrical Installations. Both the incoherency of seismic waves and wave travel effects are accounted for. The nonlinear time history analytical method is used in the analysis. The effects of boundary conditions, ground motion spatial variations, the incident angle of the seismic wave, coherency loss, and wave travel on the system are investigated. The results show that the uniform ground motion at all supports of system does not provide the most critical case for the response calculations.

  6. The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets.

    Science.gov (United States)

    Cooper, Scott T; Richters, Karl E; Melin, Travis E; Liu, Zhi-jian; Hordyk, Peter J; Benrud, Ryan R; Geiser, Lauren R; Cash, Steve E; Simon Shelley, C; Howard, David R; Ereth, Mark H; Sola-Visner, Martha C

    2012-05-15

    Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.

  7. Signatures of ice flow, retreat and meltwater delivery in the Gulf of Bothnia

    Science.gov (United States)

    Greenwood, Sarah; Clason, Caroline; Nyberg, Johan; Hell, Benjamin; Öiås, Hans; Holmlund, Per; Jakobsson, Martin

    2014-05-01

    The Gulf of Bothnia has variably played host to the main ice divide of the Fennoscandian ice sheet, ice stream onset, trunk and retreat zones, marine ice sheet decay into the large proglacial Baltic Ice Lake, and the subsequent development of an 'inland' marine basin. It is likely to have acted as both source and depocentre for the delivery of ice, water and sediment in both subglacial and ice-marginal domains. These domains and dynamics have been largely inferred from terrestrial, peripheral evidence. The submerged terrain has been little investigated and its glacial geological archives are virtually unknown. In recent years large swathes of high resolution multibeam echo-sounding data (5-10 metre grid cells) from the Baltic Sea and Gulf of Bothnia have been collected for the Swedish Maritime Administration. These data reveal, with unprecedented clarity, glacial landforms associated with the flow and retreat of ice in these basins. Multiple generations of glacial lineations associated with Baltic and Finnish ice streams are resolved, and indicate their shifting geometry and evolving dynamics. Grounding line deposits at a variety of scales allow us to characterise the style and possible rates of retreat. Our data further offer a detailed view of a dynamic subglacial hydrological system on a sediment substrate: its locally varying patterns of incision and sediment deposition, the extent and connectivity of channelised networks, and the intimate relationship between meltwater landforms, ice-marginal deposits and subglacial bedforms. Here we present these data and explore some of their implications for processes of landform creation, large-scale sediment redistribution in the Bothnian and Baltic basins, the coupling between the glacial hydrological system and ice flow/retreat dynamics, and the regional palaeo-ice sheet history.

  8. Hydrologically-induced slow-down as a mechanism for tidewater glacier retreat

    Science.gov (United States)

    Hewitt, Ian

    2017-04-01

    Outlet glaciers flowing into the ocean often terminate at a calving front, whose position is sensitively determined by the balance between ice discharge and calving/terminus-melting. Rapid retreat of tidewater glaciers can be initiated when the front is perturbed from a preferred pinning point, particularly when the glacier sits in an overdeepened trough. This is believed to make certain areas of ice sheets particularly vulnerable to ice loss. A number of factors may cause a previously stable front position to become unstable, including changes in buttressing provided by an ice shelf, and changes in ocean temperature. Another possibility is that initial retreat is induced by a reduction in the supply of ice from the interior of the ice sheet. Such a reduction can naturally arise from an increase in surface melting and runoff (in the absence of accumulation changes), and this may be amplified if more efficient meltwater routing reduces basal lubrication, as has been observed in some areas of the Greenland ice sheet. Since the initiation of rapid retreat often results in an increase of ice discharge at the front (due to increased ice thickness), such a process may not be easy to detect. In this study, I employ a simplified model of an outlet glacier and its frontal behaviour to examine the extent to which hydrologically induced slow-down of the feeding ice sheet may induce (or help to induce) calving front retreat. The model builds on earlier parameterisations of grounding line fluxes, and assumes that calving occurs according to a criterion that keeps the front close to the flotation thickness. The glacier bed is assumed to be plastic. This allows for a transparent identification of the different forcing terms affecting margin position. We conclude that hydrologically-induced slow-down of ice sheets is likely to have a more significant effect on mass loss than hydrologically-induced speed-up.

  9. Analysis of ground fault current distribution along nonuniform multi-section lines

    Energy Technology Data Exchange (ETDEWEB)

    Buccheri, P.L.; Mangione, S. [Department of Electrical, Electronic and Telecommunication Engineering, Universita degli Studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

    2008-09-15

    In case of a substation supplied by a combined overhead-cable line, most of the ground fault current flows through the cable sheaths and discharges into the soil surrounding the point of discontinuity, where cables are connected to the overhead line. In the paper a new method is presented for computing the ground fault current distribution in case of feeding line consisting of two or more different sections, i.e. part overhead and part underground cable. Besides the calculation of the earth current at the fault location, the leakage current at the transit/transition stations as well as at the overhead line towers can be evaluated, in order to ensure proper safety conditions. Based on the two-port theory, the method allows to take into account all the relevant conductively and inductively coupled parameters which take part to the fault current distribution. A computer program based on the proposed method has been developed and some application examples are reported. (author)

  10. Reconciling marine and terrestrial evidence for post LGM ice sheet retreat in southern McMurdo Sound, Antarctica

    Science.gov (United States)

    Anderson, Jacob T. H.; Wilson, Gary S.; Fink, David; Lilly, Kat; Levy, Richard H.; Townsend, Dougal

    2017-02-01

    Retreat of the Antarctic ice sheets since the Last Glacial Maximum (LGM) contributed to sea-level rise, but the location, amount, and timing of ice mass loss has been controversial. This paper presents new 10Be exposure ages from glacially transported erratics which record post LGM retreat of grounded ice in the western Ross Sea. Ice elevation in southern McMurdo Sound was ≥520 m above present day sea level on the eastern side of Mount Discovery during the LGM, and the onset of major deglaciation in the region was after 14 ka. The ice surface lowered from ∼520 to 234 m above present day sea level between 14.0 ka and 10.3 ka and from 234 m to ∼30 m between 10.3 ka and 7.4 ka. This late-glacial and Holocene deglaciation chronology from southern McMurdo Sound is consistent with other records on the margins of the Ross Embayment, and implies that the western margins of the Ross Sea Ice Sheet (RSIS) experienced most mass loss during the early to middle Holocene. These 10Be exposure ages coupled with sediment provenance define a two-stage ice flow scenario for McMurdo Sound subdividing differing reconstructions into an early and late phase. Prior to Termination I, an expanded Koettlitz Glacier flowed north and northeast between Brown Peninsula and Mount Discovery and coalesced with northward flowing ice fed from the Skelton and Mulock Glaciers. Thinning and retreat of the Koettlitz Glacier and perhaps other outlet glaciers flowing through the Royal Society Range allowed ice grounded in the Ross Sea to flow westward and northward, north of Brown Peninsula. Grounding-line recession in the Ross Sea during the late-glacial and Holocene was likely driven by Southern Ocean warming and sea-level rise from the retreat of the Northern Hemisphere ice sheets and the outer margins of the Antarctic ice sheets.

  11. The on-line electric vehicle wireless electric ground transportation systems

    CERN Document Server

    Cho, Dong

    2017-01-01

    This book details the design and technology of the on-line electric vehicle (OLEV) system and its enabling wireless power-transfer technology, the “shaped magnetic field in resonance” (SMFIR). The text shows how OLEV systems can achieve their three linked important goals: reduction of CO2 produced by ground transportation; improved energy efficiency of ground transportation; and contribution to the amelioration or prevention of climate change and global warming. SMFIR provides power to the OLEV by wireless transmission from underground cables using an alternating magnetic field and the reader learns how this is done. This cable network will in future be part of any local smart grid for energy supply and use thereby exploiting local and renewable energy generation to further its aims. In addition to the technical details involved with design and realization of a fleet of vehicles combined with extensive subsurface charging infrastructure, practical issues such as those involved with pedestrian safety are c...

  12. Ice stream reorganization and glacial retreat on the northwest Greenland shelf

    Science.gov (United States)

    Newton, A. M. W.; Knutz, P. C.; Huuse, M.; Gannon, P.; Brocklehurst, S. H.; Clausen, O. R.; Gong, Y.

    2017-08-01

    Understanding conditions at the grounding-line of marine-based ice sheets is essential for understanding ice sheet evolution. Offshore northwest Greenland, knowledge of the Last Glacial Maximum (LGM) ice sheet extent in Melville Bugt was previously based on sparse geological evidence. This study uses multibeam bathymetry, combined with 2-D and 3-D seismic reflection data, to present a detailed landform record from Melville Bugt. Seabed landforms include mega-scale glacial lineations, grounding-zone wedges, iceberg scours, and a lateral shear margin moraine, formed during the last glacial cycle. The geomorphology indicates that the LGM ice sheet reached the shelf edge before undergoing flow reorganization. After retreat of 80 km across the outer shelf, the margin stabilized in a mid-shelf position, possibly during the Younger Dryas (12.9-11.7 ka). The ice sheet then decoupled from the seafloor and retreated to a coast-proximal position. This landform record provides an important constraint on deglaciation history offshore northwest Greenland.

  13. USEPA PATHOGEN EQUIVALENCY COMMITTEE RETREAT

    Science.gov (United States)

    The Pathogen Equivalency Committee held its retreat from September 20-21, 2005 at Hueston Woods State Park in College Corner, Ohio. This presentation will update the PEC’s membership on emerging pathogens, analytical methods, disinfection techniques, risk analysis, preparat...

  14. Ground-based observation of emission lines from the corona of a red-dwarf star.

    Science.gov (United States)

    Schmitt, J H; Wichmann, R

    2001-08-02

    All 'solar-like' stars are surrounded by coronae, which contain magnetically confined plasma at temperatures above 106 K. (Until now, only the Sun's corona could be observed in the optical-as a shimmering envelope during a total solar eclipse.) As the underlying stellar 'surfaces'-the photospheres-are much cooler, some non-radiative process must be responsible for heating the coronae. The heating mechanism is generally thought to be magnetic in origin, but is not yet understood even for the case of the Sun. Ultraviolet emission lines first led to the discovery of the enormous temperature of the Sun's corona, but thermal emission from the coronae of other stars has hitherto been detectable only from space, at X-ray wavelengths. Here we report the detection of emission from highly ionized iron (Fe XIII at 3,388.1 A) in the corona of the red-dwarf star CN Leonis, using a ground-based telescope. The X-ray flux inferred from our data is consistent with previously measured X-ray fluxes, and the non-thermal line width of 18.4 km s-1 indicates great similarities between solar and stellar coronal heating mechanisms. The accessibility and spectral resolution (45,000) of the ground-based instrument are much better than those of X-ray satellites, so a new window to the study of stellar coronae has been opened.

  15. Evidence of transverse magnetospheric field line oscillations as observed from Cluster and ground magnetometers

    Directory of Open Access Journals (Sweden)

    A. K. Sinha

    2005-03-01

    Full Text Available The dynamic spectrum of ULF waves from magnetic field data obtained by the elliptically orbiting Cluster satellites (with an apogee of 119000km, perigee of 19000km and the orbital period of 57h have been prepared in the frequency range 0 to 120mHz when the satellite was near its perigee. The existence of field line oscillations, with increasing frequency in the inbound sector and decreasing frequency in the outbound sector, is seen in the transverse components, indicating the presence of independently oscillating local magnetic flux tubes in the form of transverse standing Alfvén waves. The results show that toroidal and poloidal modes are excited simultaneously. The analysis of simultaneous ground magnetometer data at the footprint of the satellite suggests that these modes are also excited due to coupling to magnetospheric waveguide modes. The clear signature of a resonant fundamental mode is seen in the ground data whereas Cluster detects a harmonic of this frequency. Lower frequency modes indicative of waveguide oscillations are seen in both the ground data and the compressional field at Cluster.

  16. Response of a transmission tower-line system at a canyon site to spatially varying ground motions

    Institute of Scientific and Technical Information of China (English)

    Hong-nan LI; Feng-long BAI; Li TIAN; Hong HAO

    2011-01-01

    Collapses of transmission towers were often observed in previous large earthquakes such as the Chi-Chi earthquake in Taiwan and Wenchuan earthquake in Sichuan, China. These collapses were partially caused by the pulling forces from the transmission lines generated from out-of-phase responses of the adjacent towers owing to spatially varying earthquake ground motions. In this paper, a 3D finite element model of the transmission tower-line system is established considering the geometric nonlinearity of transmission lines. The nonlinear responses of the structural system at a canyon site are analyzed subjected to spatially varying ground motions. The spatial variations of ground motion associated with the wave passage, coherency loss, and local site effects are given. The spatially varying ground motions are simulated stochastically based on an empirical coherency loss function and a filtered Tajimi-Kanai power spectral density function. The site effect is considered by a transfer function derived from ID wave propagation theory. Compared with structural responses calculated using the uniform ground motion and delayed excitations, numerical results indicate that seismic responses of transmission towers and power lines are amplified when considering spatially varying ground motions including site effects. Each factor of ground motion spatial variations has a significant effect on the seismic response of the structure, especially for the local site effect. Therefore, neglecting the earthquake ground motion spatial variations may lead to a substantial underestimation of the response of transmission tower-line system during strong earthquakes. Each effect of ground motion spatial variations should be incorporated in seismic analysis of the structural system.

  17. Line Strengths of Rovibrational and Rotational Transitions in the X$^2\\Pi$ Ground State of OH

    CERN Document Server

    Brooke, James S A; Western, Colin M; Sneden, Christopher; Afşar, Melike; Li, Gang; Gordon, Iouli E

    2015-01-01

    A new line list including positions and absolute intensities (in the form of Einstein $A$ values and oscillator strengths) has been produced for the OH ground X\\DP\\ state rovibrational (Meinel system) and pure rotational transitions. All possible transitions are included with v$\\primed$ and v$\\Dprimed$ up to 13, and $J$ up to between 9.5 and 59.5, depending on the band. An updated fit to determine molecular constants has been performed, which includes some new rotational data and a simultaneous fitting of all molecular constants. The absolute line intensities are based on a new dipole moment function, which is a combination of two high level ab initio calculations. The calculations show good agreement with an experimental v=1 lifetime, experimental $\\mu_\\mathrm{v}$ values, and $\\Delta$v=2 line intensity ratios from an observed spectrum. To achieve this good agreement, an alteration in the method of converting matrix elements from Hund's case (b) to (a) was made. Partitions sums have been calculated using the ...

  18. The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    Egamnazarov Georgiy

    2016-12-01

    Full Text Available Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires. Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

  19. General Fault Admittance Method Line-To-Line-To-Ground Faults In Reference And Odd Phases J.D. Sakala, J.S.J. Daka

    Directory of Open Access Journals (Sweden)

    J.D. Sakala,

    2014-02-01

    Full Text Available Line-to-line-to-ground faults are usually analysed using connection of symmetrical component networks at the fault point. As a first step, a reference phase is chosen which results in the simplest connection of the symmetrical component sequence networks for the fault. The simplest connection of symmetrical component sequence networks is a parallel one of the positive, negative and zero sequence networks when phase a of an abc phase sequence is the reference phase and the fault is taken to be between the b and c phases and ground. Putting the fault on an odd phase, say between the a and c phases and ground results in a parallel connection of the positive, negative and zero sequence networks that involve phase shifts, and the solution is more demanding. In practice, the results for the line-to-line-to-ground fault for the reference phase a may be translated to a fault on odd phases by appropriate substitution of phases. In this approach, the solution proceeds by assuming that the fault is in phases b and c and ground and that the symmetrical sequence networks are connected in parallel. The solution of the fault on b and c phases and ground is then translated to apply to the fault on odd phases, say either between phases c and a and ground or between phases a and b and ground. Alternatively, the parallel connection of the sequence networks at the fault point for the odd phases fault is solved for the symmetrical component currents and voltages.

  20. Ground-to-air flow visualization using Solar Calcium-K line Background-Oriented Schlieren

    Science.gov (United States)

    Hill, Michael A.; Haering, Edward A.

    2017-01-01

    The Calcium-K Eclipse Background-Oriented Schlieren experiment was performed as a proof of concept test to evaluate the effectiveness of using the solar disk as a background to perform the Background-Oriented Schlieren (BOS) method of flow visualization. A ground-based imaging system was equipped with a Calcium-K line optical etalon filter to enable the use of the chromosphere of the sun as the irregular background to be used for BOS. A US Air Force T-38 aircraft performed three supersonic runs which eclipsed the sun as viewed from the imaging system. The images were successfully post-processed using optical flow methods to qualitatively reveal the density gradients in the flow around the aircraft.

  1. High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Marsh, Oliver J.; Fricker, Helen A.; Siegfried, Matthew R.; Christianson, Knut; Nicholls, Keith W.; Corr, Hugh F. J.; Catania, Ginny

    2016-01-01

    Antarctica's ice shelves are thinning at an increasing rate, affecting their buttressing ability. Channels in the ice shelf base unevenly distribute melting, and their evolution provides insight into changing subglacial and oceanic conditions. Here we used phase-sensitive radar measurements to estimate basal melt rates in a channel beneath the currently stable Ross Ice Shelf. Melt rates of 22.2 ± 0.2 m a-1 (>2500% the overall background rate) were observed 1.7 km seaward of Mercer/Whillans Ice Stream grounding line, close to where subglacial water discharge is expected. Laser altimetry shows a corresponding, steadily deepening surface channel. Two relict channels to the north suggest recent subglacial drainage reorganization beneath Whillans Ice Stream approximately coincident with the shutdown of Kamb Ice Stream. This rapid channel formation implies that shifts in subglacial hydrology may impact ice shelf stability.

  2. Autonomous Inspection Robot for Power Transmission Lines Maintenance While Operating on the Overhead Ground Wires

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2011-01-01

    Full Text Available This paper describes the development of a mobile robot capable of clearing such obstacles as counterweights, anchor clamps, and torsion tower. The mobile robot walks on overhead ground wires in 500KV power tower. Its ultimate purpose is to automate to inspect the defect of power transmission line. The robot with 13 motors is composed of two arms, two wheels, two claws, two wrists, etc. Each arm has 4 degree of freedom. Claws are also mounted on the arms. An embedded computer based on PC/104 is chosen as the core of control system. Visible light and thermal infrared cameras are installed to obtain the video and temperature information, and the communication system is based on wireless LAN TCP/IP protocol. A prototype robot was developed with careful considerations of mobility. The new sensor configuration is used for the claw to grasp the overhead ground wires. The bridge is installed in the torsion tower for the robot easy to cross obstacles. The new posture plan is proposed for obstacles cleaning in the torsion tower. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  3. High-resolution absorption spectroscopy of the OH 2Pi 3/2 ground state line

    CERN Document Server

    Wiesemeyer, Helmut; Heyminck, Stefan; Karl, Jacobs; Menten, Karl; Neufeld, David; Requena-Torres, Miguel Angel; Stutzki, Jürgen; 10.1051/0004-6361/201218915

    2012-01-01

    The chemical composition of the interstellar medium is determined by gas phase chemistry, assisted by grain surface reactions, and by shock chemistry. The aim of this study is to measure the abundance of the hydroxyl radical (OH) in diffuse spiral arm clouds as a contribution to our understanding of the underlying network of chemical reactions. Owing to their high critical density, the ground states of light hydrides provide a tool to directly estimate column densities by means of absorption spectroscopy against bright background sources. We observed onboard the SOFIA observatory the 2Pi3/2, J = 5/2 3/2 2.5 THz line of ground-state OH in the diffuse clouds of the Carina-Sagittarius spiral arm. OH column densities in the spiral arm clouds along the sightlines to W49N, W51 and G34.26+0.15 were found to be of the order of 10^14 cm^-2, which corresponds to a fractional abundance of 10^-7 to 10^-8, which is comparable to that of H_2O. The absorption spectra of both species have similar velocity components, and the...

  4. Autonomous Inspection Robot for Power Transmission Lines Maintenance While Operating on the Overhead Ground Wires

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2010-12-01

    Full Text Available This paper describes the development of a mobile robot capable of clearing such obstacles as counterweights, anchor clamps, and torsion tower. The mobile robot walks on overhead ground wires in 500KV power tower. Its ultimate purpose is to automate to inspect the defect of power transmission line. The robot with 13 motors is composed of two arms, two wheels, two claws, two wrists, etc. Each arm has 4 degree of freedom. Claws are also mounted on the arms. An embedded computer based on PC/104 is chosen as the core of control system. Visible light and thermal infrared cameras are installed to obtain the video and temperature information, and the communication system is based on wireless LAN TCP/IP protocol. A prototype robot was developed with careful considerations of mobility. The new sensor configuration is used for the claw to grasp the overhead ground wires. The bridge is installed in the torsion tower for the robot easy to cross obstacles. The new posture plan is proposed for obstacles cleaning in the torsion tower. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  5. Coupling Between Microstrip Lines with Finite Width Ground Plane Embedded in Polyimide Layers for 3D-MMICs on Si

    Science.gov (United States)

    Ponchak, George E.; Dalton, Edan; Tentzeris, Emmanouil M.; Papapolymerou, John; Williams, W. Dan (Technical Monitor)

    2001-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/millimeter-wave integrated circuits on complementary metal oxide semiconductor (CMOS) (low resistivity) Si wafers. Thin film microstrip lines (TFMS) with finite width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and experimental measurements are used to show that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions.

  6. New fault location system for power transmission lines using composite fiber-optic overhead ground wire (OPGW)

    Energy Technology Data Exchange (ETDEWEB)

    Urasawa, K. (Tokyo Electric Power Co., Inc. (Japan)); Kanemaru, K.; Toyota, S.; Sugiyama, K. (Hitachi Cable, Ltd., Tokyo (Japan))

    1989-10-01

    A new fault location (FL) method using composite fiber-optic overhead ground wires (OPGWs) is developed to find out where electrical faults occur on overhead power transmission lines. This method locates the fault section by detecting the current induced in the ground wire (GW), i.e. OPGW in this system. Since detected fault information is essentially uncertain, the new FL method treats the fault information oas a current distribution pattern throughout the power line, and applies Fuzzy Theory to realize the human-like manner of fault location used by electrical power engineers. It was confirmed by computer simulations that the fault section can be accurately located using this method under various conditions. This FL system has already been applied to several commercial power transmission lines and successfully located the sections where electrical faults occurred on actual power transmission lines.

  7. Pseudo-field line resonances in ground Pc5 pulsation events

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    2005-02-01

    Full Text Available In this work we study four representative cases of Pc5 ground pulsation events with discrete and remarkably stable frequencies extended at least in a high-latitude range of ~20°; a feature that erroneously gives the impression for an oscillation mode with "one resonant field line". Additionally, the presented events show characteristic changes in polarization sense, for a meridian chain of stations from the IMAGE array, and maximize their amplitude at or close to the supposed resonant magnetic field shell, much like the typical FLR. Nevertheless, they are not authentic FLRs, but pseudo-FLRs, as they are called. These structures are produced by repetitive and tilted twin-vortex structures caused by magnetopause surface waves, which are probably imposed by solar wind pressure waves. The latter is confirmed with in-situ measurements obtained by the Cluster satellites, as well as the Geotail, Wind, ACE, and LANL 1994-084 satellites. This research effort is largely based on two recent works: first, Sarafopoulos (2004a has observationally established that a solar wind pressure pulse (stepwise pressure variation produces a twin-vortex (single vortex current system over the ionosphere; second, Sarafopoulos (2004b has studied ground events with characteristic dispersive latitude-dependent structures and showed that these are associated with twin-vortex ionosphere current systems. In this work, we show that each pseudo-FLR event is associated with successive and tilted large-scale twin-vortex current systems corresponding to a magnetopause surface wave with wavelength 10-20RE. We infer that between an authentic FLR, which is a spatially localized structure with an extent 0.5RE in the magnetospheric equatorial plane, and the magnetopause surface wavelength, there is a scale factor of 20-40. A chief observational finding, in this work, is that there are Pc5 ground pulsation events showing two gradual and latitude

  8. The resident retreat for future academicians.

    Science.gov (United States)

    Culton, Donna A; Rubenstein, David S; Diaz, Luis A

    2010-07-01

    The first Resident Retreat for Future Academicians was held in 2001 with the goal of recruiting and encouraging talented residents interested in careers in academia. In this issue of the JID, Hill et al. present findings to suggest that the retreat has indeed fulfilled its goal. It is our hope that the retreat, which is now in its tenth year, will continue to enlist the future leaders of our specialty.

  9. The Connemara Fan: a major glacial grounding line fan west of Ireland

    Science.gov (United States)

    McCarron, Stephen; Praeg, Daniel; Monteys, Xavier; Scott, Gill

    2014-05-01

    Glacigenic topography on the mid-shelf (~130-350 m water depth) west of Galway, Ireland appears to have the morphological form, internal architecture and sediments associated with a large glacial grounding-line fan. Seismic data collected in 2009 and 2012 (during the GLAMAR and GATEWAYS 1 campaigns) reveal that the broad, arcuate ridges of the 'Olex moraine' form the landward part of a fan system which prograded beyond the mid-shelf break (defining the outer margin of the 'Clare Platform') westwards into the Porcupine Seabight. The topography is comparable to larger shelf-edge trough-mouth fans found further north along the same margin, however no discernible 'trough' has been identified on the Clare Platform. The ridge and fan topographic assemblage is renamed the 'Connemara Fan' in its entirety, based on its genetic relations and geographic location due west of Connemara, western Ireland. A macrofossil recovered from within a debris flow on the outer fan slope comprised of remobilised plumites dates to ~ 20 ka Cal B.P., indicating sediment reworking downslope following deglacial sediment input to at least that time. The Connemara Fan is the most southerly glacigenic fan identified along the north-east Atlantic margin. Its identification also adds to our knowledge of possibly multiple generations of ice sheets feeding onto the Irish shelf from west-central Ireland and the occurrence of ice sheet geometries and dynamics that evacuated ice, melt-water and sediment (ice streams?) westwards across the Clare Platform during past glaciations.

  10. Impaired skeletal muscle regeneration in the absence of fibrosis during hibernation in 13-lined ground squirrels.

    Directory of Open Access Journals (Sweden)

    Eva Andres-Mateos

    Full Text Available Skeletal muscle atrophy can occur as a consequence of immobilization and/or starvation in the majority of vertebrates studied. In contrast, hibernating mammals are protected against the loss of muscle mass despite long periods of inactivity and lack of food intake. Resident muscle-specific stem cells (satellite cells are known to be activated by muscle injury and their activation contributes to the regeneration of muscle, but whether satellite cells play a role in hibernation is unknown. In the hibernating 13-lined ground squirrel we show that muscles ablated of satellite cells were still protected against atrophy, demonstrating that satellite cells are not involved in the maintenance of skeletal muscle during hibernation. Additionally, hibernating skeletal muscle showed extremely slow regeneration in response to injury, due to repression of satellite cell activation and myoblast differentiation caused by a fine-tuned interplay of p21, myostatin, MAPK, and Wnt signaling pathways. Interestingly, despite long periods of inflammation and lack of efficient regeneration, injured skeletal muscle from hibernating animals did not develop fibrosis and was capable of complete recovery when animals emerged naturally from hibernation. We propose that hibernating squirrels represent a new model system that permits evaluation of impaired skeletal muscle remodeling in the absence of formation of tissue fibrosis.

  11. ATOMIC DATA FOR ABSORPTION-LINES FROM THE GROUND-LEVEL AT WAVELENGTHS GREATER-THAN-228-ANGSTROM

    NARCIS (Netherlands)

    VERNER, DA; BARTHEL, PD; TYTLER, D

    1994-01-01

    We list wavelengths, statistical weigths and oscillator strengths for 2249 spectral lines arising from the ground states of atoms and ions. The compilation covers all wavelengths longward of the HeII Lyman limit at 227.838 Angstrom and all the ion states of all elements from hydrogen to bismuth (Z =

  12. Greenland ice sheet retreat history in the northeast Baffin Bay based on high-resolution bathymetry

    Science.gov (United States)

    Slabon, Patricia; Dorschel, Boris; Jokat, Wilfried; Myklebust, Reidun; Hebbeln, Dierk; Gebhardt, Catalina

    2016-12-01

    New swath-bathymetric data acquired in 2010 and 2015 indicate a variety of glacial landforms in cross-shelf troughs of the Melville Bay (northeast Baffin Bay). These landforms reveal that, at their maximum extent, ice streams in the troughs crossed the shelf all the way to the shelf edge. Moraines, grounding-zone wedges (GZWs) and subglacial till lobes on the continental shelf define a pattern of variable ice stream retreat in the individual troughs. On the outer shelf, in the northern cross-shelf trough, ice-stream retreat was slow compared to more episodic retreat in the central (at least one stabilization on the outer shelf) and southern cross-shelf trough (re-advances at the shelf edge and fast retreat thereafter). Large GZWs on the mid-to inner shelf of the troughs indicate periods of grounding-zone stabilization. According to glacial landforms, the final retreat across the inner shelf (before 8.41 ka BP) was episodic to slow. Furthermore, evidence has been found for localized ice domes with minor ice-streams on inter-trough banks. The glacial landforms in Melville Bay, thus, indicate the varying and discontinuous ice sheet retreat history across the Northwest Greenland continental shelf.

  13. Method of Calculation of Current of the Ground Faults in the Parallel Overhead Transmission Lines 110-220 Kv

    Directory of Open Access Journals (Sweden)

    Ukraintsev Alexandr V.

    2017-01-01

    Full Text Available The mutual induction between the phase wires of the different overhead lines which situate close to each other cause unbalanced redistribution of currents in the line wires. This leads to emergence of the outof-balance zero sequence current which affects negatively on the sensitivity of the zero-sequence current protection. It is impossible to estimate such out-ofbalance current by the means of the typical calculation programs for short circuit currents. This paper describes the method of “virtual” lines for an extra correction of the values of zero-sequence currents during the current ground faults happening in the overhead lines 110-220 kV. There is an example of using this method for three parallel overhead lines 220 kV passing close to each other.

  14. Kinematic first-order calving law implies potential for abrupt ice-shelf retreat

    Science.gov (United States)

    Levermann, A.; Albrecht, T.; Winkelmann, R.; Martin, M. A.; Haseloff, M.; Joughin, I. R.

    2012-12-01

    Recently observed large-scale disintegration of Antarctic ice shelves has moved their fronts closer towards grounded ice. In response, ice-sheet discharge into the ocean has accelerated, contributing to global sea-level rise and emphasizing the importance of calving-front dynamics. The position of the ice front strongly influences the stress field within the entire sheet-shelf-system and thereby the mass flow across the grounding line. While theories for an advance of the ice-front are readily available, no general rule exists for its retreat, making it difficult to incorporate the retreat in predictive models. Here we extract the first-order large-scale kinematic contribution to calving which is consistent with large-scale observation. We emphasize that the proposed equation does not constitute a comprehensive calving law but represents the first-order kinematic contribution which can and should be complemented by higher order contributions as well as the influence of potentially heterogeneous material properties of the ice. When applied as a calving law, the equation naturally incorporates the stabilizing effect of pinning points and inhibits ice shelf growth outside of embayments. It depends only on local ice properties which are, however, determined by the full topography of the ice shelf. In numerical simulations the parameterization reproduces multiple stable fronts as observed for the Larsen A and B Ice Shelves including abrupt transitions between them which may be caused by localized ice weaknesses. We also find multiple stable states of the Ross Ice Shelf at the gateway of the West Antarctic Ice Sheet with back stresses onto the sheet reduced by up to 90% compared to the present state. Eigencalving: Universal kinematic contribution to iceberg calving of ice shelves. Calving rate C is proportional to the eigenvalues of the horizontal spreading rate tensor.

  15. Impact of SSSC on Measured Impedance in Single Phase to Ground Fault Condition on 220 kV Transmission Line

    Directory of Open Access Journals (Sweden)

    Mohamed ZELLAGUI

    2012-08-01

    Full Text Available This paper presents and compares the impact of SSSC on measured impedance for single phase to ground fault condition. The presence of Static Synchronous SSSC on a transmission line has a great influence on the ZRelay in distance protection. The protection of the high voltage 220 kV single circuit transmission line in eastern Algerian electrical transmission networks is affected in the case with resistance fault RF. The paper investigate the effect of Static Synchronous Series Compensator (SSSC on the measured impedance (Relay taking into account the distance fault point (n and fault resistance (RF. The resultants simulation is performed in MATLAB software environment.

  16. Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity

    Science.gov (United States)

    Fagre, D. B.

    2008-12-01

    Mountain glaciers continue to retreat rapidly over most of the globe. In North America, at Glacier National Park, Montana, recent research results from Sperry Glacier (2005-2007) indicate negative mass balances are now 3-4 times greater than in the 1950s. A geospatial model of glacier retreat in the Blackfoot-Jackson basin suggested all glaciers would be gone by 2030 but has proved too conservative. Accelerated glacier shrinkage since the model was developed has mirrored an increase in actual annual temperature that is almost twice the rate used in the model. The glaciers in Glacier National Park are likely to be gone well before 2030. A variety of media, curricula, and educational strategies have been employed to communicate the disappearance of the glaciers as a consequence of global warming. These have included everything from print media and television coverage to podcasts and wayside exhibits along roads in the park. However, a new thrust is to partner with artists to communicate climate change issues to new audiences and through different channels. A scientist-artist retreat was convened to explore the tension between keeping artistic products grounded in factually-based reality while providing for freedom to express artistic creativity. Individual artists and scientists have worked to create aesthetic and emotional images, using painting, poetry, music and photography, to convey core messages from research on mountain ecosystems. Finally, a traveling art exhibit was developed to highlight the photography that systematically documents glacier change through time. The aim was to select photographs that provide the most compelling visual experience for an art-oriented viewer and also accurately reflect the research on glacier retreat. The exhibit opens on January 11, 2009

  17. LINES

    Directory of Open Access Journals (Sweden)

    Minas Bakalchev

    2015-10-01

    Full Text Available The perception of elements in a system often creates their interdependence, interconditionality, and suppression. The lines from a basic geometrical element have become the model of a reductive world based on isolation according to certain criteria such as function, structure, and social organization. Their traces are experienced in the contemporary world as fragments or ruins of a system of domination of an assumed hierarchical unity. How can one release oneself from such dependence or determinism? How can the lines become less “systematic” and forms more autonomous, and less reductive? How is a form released from modernistic determinism on the new controversial ground? How can these elements or forms of representation become forms of action in the present complex world? In this paper, the meaning of lines through the ideas of Le Corbusier, Leonidov, Picasso, and Hitchcock is presented. Spatial research was made through a series of examples arising from the projects of the architectural studio “Residential Transformations”, which was a backbone for mapping the possibilities ranging from playfulness to exactness, as tactics of transformation in the different contexts of the contemporary world.

  18. Glacial Retreat in Chilean Patagonia

    Science.gov (United States)

    2002-01-01

    The San Quintin Glacier is the largest outflow glacier of the Northern Patagonian Ice Field in southern Chile. Its terminus is a piedmont lobe just short of the Golfo de Penas on the Pacific Ocean and just north of 47oS. Like many glaciers worldwide during the twentieth century, San Quintin appears to be losing mass and possibly retreating. Such a change is evident in these two photographs taken by astronauts only seven years apart. The first was taken by the crew of STS-068 in October1994 and the second by the Increment 4 crew of the International Space Station in February 2002. Even with the reversal of season and different lighting conditions of these two acquisitions, a loss of mass and change of structure, particularly in the lobe, are strikingly evident in these comparative photos. Glaciers are one of the special topics identified as scientific objectives for monitoring with photography from the International Space Station. Astronaut photography is a complimentary source of remote sensing data available for use with other sensor systems being used to monitor and study glaciers (see an ASTER image of the San Quintin Glacier). They also provide strong, visual context information on glacier environments and processes using a familiar medium, the camera. Images STS068-260-73 and ISS004-E-7267 were provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  19. Transition and verification of ground fault protection method in Hokuriku Shinkansen line

    Directory of Open Access Journals (Sweden)

    Michiteru Koyanagi

    2016-01-01

    Full Text Available The electrical discharge gaps called S type horn are applied to the ground fault detection and protection in AC traction power supply system for high speed railway called Shinkansen. In this method, the earth resistance of the steel pipe pillar is an important factor for the ground fault protection by the electrical discharge. In this study, the analyses of the transient characteristics of grounding fault are carried out by using EMTP, and the ground resistance value required to trigger discharge at S type horn was calculated. Moreover, the protection effect of a discharge gap called GP the substation equipment that is a discharge gap which is inserted between rails and substation mesh is evaluated.

  20. Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica

    OpenAIRE

    Rebesco, M.; Domack, E.; Zgur, F.; Lavoie, C.; Leventer, A.; Brachfeld, S.; Willmott, V.; Halverson, G.; M. Truffer; Scambos, T; Smith, J.; E. Pettit

    2014-01-01

    Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the ...

  1. Retroceso de la línea de costa en las Grütas, provincia de Río Negro Retreat of the line of coast in Las Grutas, Río Negro province

    Directory of Open Access Journals (Sweden)

    Roberto R Kokot

    2012-03-01

    Full Text Available La localidad de Las Grutas, ubicada en la provincia de Río Negro, presenta una costa acantilada con una extensa plataforma litoral. Estas geoformas están constituidas por sedimentitas paleógenas correspondientes a la Formación Gran Bajo del Gualicho. Sobre las mismas se apoyan en discordancia erosiva depósitos de cordones litorales pleistocenos y la secuencia culmina con depósitos de dunas holocenos. Mediante la comparación de fotografías aéreas e imágenes satelitales, se determinó el grado de erosión entre los años 1969 y 2008. El retroceso fue estudiado a través de la comparación de fotografías aéreas e imágenes satelitales georreferenciadas. Los resultados muestran una tendencia a la reducción de los campos de dunas, al retroceso de las plataformas litorales y de la línea de costa. Esta última presenta una tasa de erosión media de 1,50 m en el lapso de 39 años. Sin embargo, los sectores céntricos y septentrionales fueron más afectados alcanzando hasta 3 m de retroceso en ese período. La erosión y los consecuentes procesos de remoción en masa responden principalmente a la intensa acción del oleaje sobre los afloramientos costeros, especialmente en los sectores de costa más expuestos a las rompientes, así como a los condicionantes geológico/estructurales de los afloramientos expuestos. El escenario de peligrosidad es acentuado por la acción antrópica que contribuye con la aceleración de los procesos naturales.The town of Las Grutas, province of Río Negro, has a cliffed coastline with an extensive coastal platform. Mentioned land-forms are formed above Paleogene sedimentary rocks for the Gran Bajo del Gualicho Formation. Rely on them in erosive unconformity Pleistocene beach ridges deposits and the sequence ends with Holocene dune deposits. By comparing aerial photographs and satellite images, it was determined that the coast was eroded from 1969 to nowadays. The retreat was studied by comparing aerial

  2. The retreatment: Indications, technique and results

    Energy Technology Data Exchange (ETDEWEB)

    Islak, Civan, E-mail: cislak@istanbul.edu.tr [Istanbul University, Cerrahpasa Medical Faculty, Department of Radiology, Division of Neuroradiology, Kocamustafapasa, Istanbul 34098 (Turkey)

    2013-10-01

    Durability of endovascular treatment of intracranial aneurysms has always been an issue and a very strong point of criticism. Although studies on long-term results have made it clear that endovascular treatment safe and effective they, nonetheless showed retreatment after endovascular treatment is nearly 5–10 times more frequent than surgical clipping. Risk factors predisposing high probability of retreatment are aneurysm with dissecting nature, incomplete coiling, sac size larger than 10 mm and localization at the bifurcations such as basilar tip. The indications for retreatment after endovascular treatment are not clear yet, although certain morphologic criteria can be used. Retreatment appears not to negate the initial advantage of endovascular treatment over surgical treatment and can be performed very small morbi-mortality numbers.

  3. Cooperative Spatial Retreat for Resilient Drone Networks.

    Science.gov (United States)

    Kang, Jin-Hyeok; Kwon, Young-Min; Park, Kyung-Joon

    2017-05-03

    Drones are broadening their scope to various applications such as networking, package delivery, agriculture, rescue, and many more. For proper operation of drones, reliable communication should be guaranteed because drones are remotely controlled. When drones experience communication failure due to bad channel condition, interference, or jamming in a certain area, one existing solution is to exploit mobility or so-called spatial retreat to evacuate them from the communication failure area. However, the conventional spatial retreat scheme moves drones in random directions, which results in inefficient movement with significant evacuation time and waste of battery lifetime. In this paper, we propose a novel spatial retreat technique that takes advantage of cooperation between drones for resilient networking, which is called cooperative spatial retreat (CSR). Our performance evaluation shows that the proposed CSR significantly outperforms existing schemes.

  4. Management of multidrug-resistant tuberculosis and patients in retreatment.

    Science.gov (United States)

    Caminero, J A

    2005-05-01

    Retreatment of tuberculosis involves the management of entities as diverse as relapse, failure, treatment after default, and poor patient adherence to the previous treatment. The emergence of conditions for selection of resistance (failure and partial abandonment) is a matter of great concern. The development of a retreatment regimen for tuberculosis requires consideration of certain basic premises. The importance of a comprehensive and directed history of drugs taken in the past, and the limited reliability of susceptibility tests to many of these drugs, should be kept in mind. Taking this into account, and possessing a thorough knowledge of all anti-tuberculosis medications, it is possible to cure almost all patients with an appropriate retreatment regimen including a minimum of three or four drugs not previously used. Nonetheless, the treatment of these patients is so complex that it should only be carried out by experienced staff. Concern about treating tuberculosis patients with drug resistance varies greatly depending on the available resources. High-income countries should provide individual treatment regimens adapted to each patient; however, in other settings, restricted resources could justify the implementation of standardised therapeutic guidelines with second-line drugs in order to facilitate management and reduce costs.

  5. Potential of the solid-Earth response for limiting long-term West Antarctic Ice Sheet retreat

    Science.gov (United States)

    Konrad, Hannes; Sasgen, Ingo; Pollard, David; Klemann, Volker

    2016-04-01

    The West Antarctic Ice Sheet (WAIS) is assumed to be inherently unstable because it is grounded below sea level in a large part, where the bedrock deepens from today's grounding line towards the interior of the ice sheet. Idealized simulations have shown that bedrock uplift due to isostatic adjustment of the solid Earth and the associated sea-level fall may stop the retreat of such a marine-based ice sheet (Gomez et al., 2012). Here, we employ a coupled model for ice-sheet dynamics and solid-Earth dynamics, including a gravitationally consistent description of sea level, to investigate the influence of the viscoelastic Earth structure on the WAIS' future stability (Konrad et al. 2015). For this, we start from a steady-state condition for the Antarctic Ice Sheet close to present-day observations and apply atmospheric and oceanic forcing of different strength to initiate the retreat of the WAIS and investigate the effect of the viscoelastic deformation on the ice evolution for a range of solid-Earth rheologies. We find that the climate forcing is the primary control on the occurrence of the WAIS collapse. However, for moderate climate forcing and a weak solid-Earth rheology associated with the West Antarctic rift system (asthenosphere viscosities of 3x10^19 Pa s or less), we find that the combined effect of bedrock uplift and gravitational sea-level fall limits the retreat to the Amundsen Sea embayment on millennial time scales. In contrast, a stiffer Earth rheology yields a collapse under these conditions. Under a stronger climate forcing, weak Earth structures do not prevent the WAIS collapse; however, they produce a delay of up to 5000 years in comparison to a stiffer solid-Earth rheology. In an additional experiment, we test the impact of sea-level rise from an assumed fast deglaciation of the Greenland Ice Sheet. In cases when the climatic forcing is too weak to force WAIS collapse by itself, the additional rise in sea-level leads to disintegration of the WAIS

  6. Himalayan glacier retreat delayed by debris cover

    Science.gov (United States)

    Scherler, D.; Bookhagen, B.; Strecker, M. R.

    2010-12-01

    Variable retreat rates and paucity of mass-balance data complicate a coherent picture of the current state and future fate of Himalayan glaciers. We report frontal changes and remotely-sensed surface velocities from >250 glaciers in the greater Himalayan realm (Hindu Kush, Karakoram, Himalaya, West Kunlun Shan) between 2000 and 2008 that provide evidence for widespread meltdown, which is obscured by debris cover. While debris-free glaciers in Tibet and other low-relief areas have been mainly retreating, debris-covered glaciers in high-relief areas, such as the central Himalaya, were mostly stagnating and in-situ down wasting but not retreating. Only Karakoram glaciers show no signs of stagnation or appreciable retreat, despite high debris cover, suggesting no recent mass loss. Our study shows that regional differences in topographic relief account for substantial differences in debris cover and thus retreat behaviour that need to be considered when comparing glacier retreat rates. The combination of melt rates lowered by debris cover and healthier glaciers in the strongly glaciated Karakoram slows down current glacier wastage in High Asia. Predictions of future water availability and global sea level have so far neglected the effect of debris cover on glacier melt rates and thus likely overestimate the speed of glacier meltdown in the Himalaya and other steep mountain ranges where debris covered glaciers are common.

  7. Facies and depositional architecture according to a jet efflux model of a late Paleozoic tidewater grounding-line system from the Itararé Group (Paraná Basin), southern Brazil

    Science.gov (United States)

    Aquino, Carolina Danielski; Buso, Victoria Valdez; Faccini, Ubiratan Ferrucio; Milana, Juan Pablo; Paim, Paulo Sergio Gomes

    2016-04-01

    During the Late Paleozoic, the Gondwana supercontinent was affected by multiple glacial and deglacial episodes known as "The Late Paleozoic Ice Age" (LPIA). In Brazil, the evidence of this episode is recorded mainly by widespread glacial deposits preserved in the Paraná Basin that contain the most extensive record of glaciation (Itararé Group) in Gondwana. The Pennsylvanian to early Permian glaciogenic deposits of the Itararé Group (Paraná Basin) are widely known and cover an extensive area in southern Brazil. In the Doutor Pedrinho area (Santa Catarina state, southern Brazil), three glacial cycles of glacier advance and retreat were described. The focus of this article is to detail the base of the second glacial episodes or Sequence II. The entire sequence records a deglacial system tract that is represented by a proximal glacial grounding-line system covered by marine mudstones and shales associated with a rapid flooding of the proglacial area. This study deals with the ice proximal grounding-line systems herein interpreted according to lab model named plane-wall jet with jump. Detailed facies analysis allowed the identification of several facies ranging from boulder-rich conglomerates to fine-grained sandstones. No fine-grained deposits such as siltstone or shale were recorded. According to this model, the deposits are a product of a supercritical plane-wall outflow jet that changes to a subcritical jet downflow from a hydraulic jump. The hydraulic jump forms an important energy boundary that is indicated by an abrupt change in grain size and cut-and-fill structures that occur at the middle-fan. The sedimentary facies and facies associations show a downflow trend that can be subdivided into three distinct stages of flow development: (1) a zone of flow establishment (ZFE), (2) a zone of transition (ZFT), and (3) an established zone (ZEF). The proximal discharge is characterized by hyperconcentrated-to-concentrated flow due to the high energy and sediment

  8. Towards the development of integrated monitoring system for retreat mining operations

    Institute of Scientific and Technical Information of China (English)

    HAMID Maleki

    2008-01-01

    Through cooperative research between the government, the private sector,mining companies and equipment manufacturers, considerable progress had been madeduring the last decade in studying the mechanics of strata failure and acquiring the know-ledge needed to develop an integrated monitoring system for assessing local roof stability.Because of higher geotechnical risks in retreat mining operations, it was both important todevelop panel layout designs that control convergence and stress and to monitor groundresponse during operations to verify designs and provide warning of impending stabilityproblems. For detecting both localized roof stability problems and global overburden col-lapse mechanisms, the proposes an integrated panel-wide monitoring system which com-bines the capabilities of load rate monitoring of mobile roof supports (MRSs) with deforma-tion measurements using an extensive array of sensors located near the mining face andthroughout the panel. Two monitoring methods for the detection of localized roof stabilityproblems have been evaluated on the basis of mine measurements and numerical model-ing considerations. These are load rate monitoring of the hydraulic cylinders of mobile roofsupport (MRS) and re mote monitoring of roof movements. Analyses of field data in retreatsections show that roof instabilities are influenced by: (1) pillar failure, (2) pillar yielding, (3)mine seismicity (bumps), (4) geologic structures, and (5) panel layout designs and practice.Pillar yielding and unloading can be conveniently monitored by the load rate monitoringdevice, but to detect impending localized roof falls, additional ground deformation meas-urements are needed near the mining face. By increasing the number of deformationmeasurements in the entire panel, additional safeguards can be achieved for detectingoverburden collapse mechanisms while continuously monitoring local roof stability close tothe retreat line.

  9. The effect of a power-law mantle viscosity on trench retreat rate

    Science.gov (United States)

    Holt, Adam F.; Becker, Thorsten W.

    2017-01-01

    The subduction of lithospheric plates is partitioned between subducting plate motion and lateral slab migration (i.e. trench retreat and advance). We use 3-D, dynamic models of subduction to address the role of a power-law mantle viscosity on subduction dynamics and, in particular, rates of trench retreat. For all numerical models tested, we find that a power-law rheology results in reduced rates of trench retreat, and elevated slab dip angles, relative to the equivalent isoviscous mantle model. We analyse the asthenospheric pressure distribution and the style of mantle flow, which exhibits only limited variability as a function of mantle rheology, in order to compute estimates of the mantle forces associated with subduction. The inclusion of a power-law rheology reduces the mantle shear force (which resists subducting plate motion) to a greater degree than it reduces the dynamic pressure gradient across the slab (which resists trench retreat). Therefore, the inclusion of a power-law mantle rheology favours a shift towards a subduction mode with a reduced trench retreat component, typically a relative reduction of order 25 per cent in our 3-D models. We suggest that this mechanism may be of importance for reducing the high trench retreat rates observed in many previous models to levels more in line with the average subduction partitioning observed on Earth at present (i.e. trench velocity ≤ plate velocity), for most absolute plate motion reference frames.

  10. Reliable Refuge: Two Sky Island Scorpion Species Select Larger, Thermally Stable Retreat Sites.

    Science.gov (United States)

    Becker, Jamie E; Brown, Christopher A

    2016-01-01

    Sky island scorpions shelter under rocks and other surface debris, but, as with other scorpions, it is unclear whether these species select retreat sites randomly. Furthermore, little is known about the thermal preferences of scorpions, and no research has been done to identify whether reproductive condition might influence retreat site selection. The objectives were to (1) identify physical or thermal characteristics for retreat sites occupied by two sky island scorpions (Vaejovis cashi Graham 2007 and V. electrum Hughes 2011) and those not occupied; (2) determine whether retreat site selection differs between the two study species; and (3) identify whether thermal selection differs between species and between gravid and non-gravid females of the same species. Within each scorpion's habitat, maximum dimensions of rocks along a transect line were measured and compared to occupied rocks to determine whether retreat site selection occurred randomly. Temperature loggers were placed under a subset of occupied and unoccupied rocks for 48 hours to compare the thermal characteristics of these rocks. Thermal gradient trials were conducted before parturition and after dispersal of young in order to identify whether gravidity influences thermal preference. Vaejovis cashi and V. electrum both selected larger retreat sites that had more stable thermal profiles. Neither species appeared to have thermal preferences influenced by reproductive condition. However, while thermal selection did not differ among non-gravid individuals, gravid V. electrum selected warmer temperatures than its gravid congener. Sky island scorpions appear to select large retreat sites to maintain thermal stability, although biotic factors (e.g., competition) could also be involved in this choice. Future studies should focus on identifying the various biotic or abiotic factors that could influence retreat site selection in scorpions, as well as determining whether reproductive condition affects thermal

  11. Successful alemtuzumab retreatment in progressive B-cell chronic lymphocytic leukemia: a multicenter survey in 30 patients.

    Science.gov (United States)

    Fiegl, Michael; Falkner, Florian; Steurer, Michael; Zojer, Niklas; Hopfinger, Georg; Haslbauer, Ferdinand; Winder, Guntram; Voskova, Daniela; Andel, Johannes; Lang, Alois; Brychtova, Yvona; Mayer, Jiri; Greil, Richard; Gastl, Günther

    2011-09-01

    Although retreatment with alemtuzumab in relapsing B-cell chronic lymphocytic leukemia (CLL) may be beneficial, there has thus far been no thorough analysis available on this topic. Data were collected from 30 chemotherapy-pretreated patients with progressive CLL who had received alemtuzumab twice in consecutive, distinct therapy lines. The median dose of alemtuzumab retreatment was 402 mg (range, 43-1,090 mg). Retreatment with alemtuzumab induced an overall response rate of 47%. From the start of alemtuzumab retreatment, median progression-free survival (PFS) and overall survival (OS) were 6.3 and 20.0 months, respectively. Response rates, PFS and OS upon alemtuzumab retreatment were correlated with response to initial alemtuzumab treatment, the time interval between the initial course of alemtuzumab and start of retreatment, and the hemoglobin concentration prior to retreatment. Reported toxicities from 24 cases included infections (50%), febrile reactions upon alemtuzumab administration (38%), exanthema (21%), and grade 4 neutropenia (13%) and thrombocytopenia (17%). We conclude that alemtuzumab retreatment represents an effective and tolerable therapeutic option for selected patients with CLL.

  12. Hillslope failure and paraglacial reworking of sediments in response to glacier retreat, Fox Valley, New Zealand.

    Science.gov (United States)

    McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie

    2017-04-01

    Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley

  13. Measuring galaxy [OII] emission line doublet with future ground-based wide-field spectroscopic surveys

    CERN Document Server

    Comparat, Johan; Bacon, Roland; Mostek, Nick J; Newman, Jeffrey A; Schlegel, David J; Yèche, Christophe

    2013-01-01

    The next generation of wide-field spectroscopic redshift surveys will map the large-scale galaxy distribution in the redshift range 0.7< z<2 to measure baryonic acoustic oscillations (BAO). The primary optical signature used in this redshift range comes from the [OII] emission line doublet, which provides a unique redshift identification that can minimize confusion with other single emission lines. To derive the required spectrograph resolution for these redshift surveys, we simulate observations of the [OII] (3727,3729) doublet for various instrument resolutions, and line velocities. We foresee two strategies about the choice of the resolution for future spectrographs for BAO surveys. For bright [OII] emitter surveys ([OII] flux ~30.10^{-17} erg /cm2/s like SDSS-IV/eBOSS), a resolution of R~3300 allows the separation of 90 percent of the doublets. The impact of the sky lines on the completeness in redshift is less than 6 percent. For faint [OII] emitter surveys ([OII] flux ~10.10^{-17} erg /cm2/s like ...

  14. Two independent methods for mapping the grounding line of an outlet glacier – example from the Astrolabe Glacier, Terre Adélie, Antarctica

    Directory of Open Access Journals (Sweden)

    E. Le Meur

    2013-08-01

    Full Text Available The grounding line is a key element acting on the dynamics of coastal outlet glaciers. Knowing its position accurately is fundamental for both modelling the glacier dynamics and establishing a benchmark to which one can later refer in case of change. Here we map the grounding line of the Astrolabe Glacier in East Antarctica (66°41´ S; 140°05´ E, using hydrostatic and tidal methods. The first method is based on new surface and ice thickness data from which the line of buoyant flotation is found. We compare this hydrostatic map with kinematic GPS measurements of the tidal response of the ice surface. By detecting the transitions where the ice starts to move vertically in response to the tidal forcing we find control points for the grounding line position along GPS profiles. %If it can be shown that the long-term viscous mechanical behaviour of the ice slab validates the hydrostatic approach, mapping the grounding line from the ice supper surface displacements conversely requires correcting for the rigid elastic slab effect that dominates at tidal frequencies. With the help of a 2-dimensional elastic plate model, rigid elastic deviations are computed and applied to these control points. Once the extent of the grounding zone, the kinematic approach is consistent with the hydrostatic map. These two approaches lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates from those obtained so far from satellite imagery.

  15. Summary of the RHIC Retreat 2007

    Energy Technology Data Exchange (ETDEWEB)

    Pilat,F.; Gardner, C.; Montag, C.; Roser, T.

    2008-08-01

    The RHIC Retreat 2007 took place on July 16-17 2007 at the Foxwoods Resort in CT, about 3 weeks after the end of the RHIC Run-7. The goal of the Retreat is traditionally to plan the upcoming run in the light of the results from the previous one, by providing a snapshot of the present understanding of the machine and a forum for free and frank discussion. A particular attention was paid to the challenge of increasing the time at store, and the related issue of system reliability. An interesting Session covered all new developments aimed to improve the machine performance and luminosity. In Section 2 we summarize the results from Run-7 for RHIC and the injectors and discuss the present objectives of the RHIC program and performance. Sections 3-6 are summaries of the Retreat sessions focused on preparation for deuteron gold and polarized protons, respectively, machine availability and new developments.

  16. Ice stream retreat following the LGM and onset of the west Greenland current in Uummannaq Trough, west Greenland

    Science.gov (United States)

    Sheldon, Christina; Jennings, Anne; Andrews, John T.; Ó Cofaigh, Colm; Hogan, Kelly; Dowdeswell, Julian A.; Seidenkrantz, Marit-Solveig

    2016-09-01

    The deglacial history and oceanography of Uummannaq Trough, central West Greenland continental shelf, was investigated using foraminiferal, sedimentological, and bathymetric records together with a radiocarbon chronology, providing a timeline for the retreat of glacial ice after the Last Glacial Maximum (LGM). To map ice stream retreat, data were collected from cores from the outer (JR175-VC45 and JR175-VC43) and inner (JR175-VC42) Uummannaq Trough. A large ice stream, fed by confluent glaciers draining the interior of the Greenland Ice Sheet, extended across the outer shelf during the LGM and was in retreat by 15.0 cal kyr BP. Foraminiferal data indicate that the 'warm' West Greenland Current (WGC) was established prior to 14.0 cal kyr BP, which is the hitherto earliest record of Atlantic Water found on the West Greenland shelf. For each of the cores, foraminifera indicate that ice sheet retreat was followed quickly by incursion of the WGC, suggesting that the warm water may have enhanced ice retreat. Prior to the Younger Dryas cold event, the radiocarbon chronology indicates that the ice sheet retreated to the mid-shelf, where it subsequently stabilised and formed a large grounding-zone wedge (GZW). After the Younger Dryas, around 11.5 cal kyr BP, the ice retreated rapidly from the GZW and into the fjords.

  17. Analysis of the grounding system for a mobile communication site placed on HV power line mast

    Science.gov (United States)

    Bîrsan, I.; Munteanu, C.; Horgoș, M.; Ilut, T.

    2016-08-01

    This paper aims to analyze the potential distribution on the soil surface or potential variation on the main directions inside computing mobile site. I want to study a system made the earth a mobile communications site, antennas operator and the system of which the earth is placed on a High Voltage Power Line Mast (LEA 110 KV). I made direct measurements and I use a 3D software for analyze the results and simulating some possible solutions.

  18. Capacitance sensor for automatic soil retreat measurements

    Institute of Scientific and Technical Information of China (English)

    GU Jun; YANG Juan; YIN Wu-liang; WANG Chao; WANG Hua-xiang; LIU Ze; CHENG Su-sen

    2008-01-01

    To continuously monitor the soil retreat due to erosion in field, provide valuable information about the erosion processes and overcome the disadvantages of inefficiency, high time-consumption and labor-intensity of existing methods, this paper describes a novel capacitance sensor for measuring the soil retreat. A capaci-tance sensor based probe is proposed, which can measure the depth of the soil around it automatically and the data can be recorded by a data logger. Experimental results in the lab verify its usefulness.

  19. Orthograde retreatment and apexification after unsuccessful endodontic treatment, retreatment and apicectomy.

    Science.gov (United States)

    Sedgley, C M; Wagner, R

    2003-11-01

    To describe a case where a second orthograde retreatment was successful in the management of an infected mandibular right first molar that previously had received both orthograde and retrograde treatments. Periapical surgery is unlikely to be successful unless the root canal system has been adequately debrided and sealed. A case is described where orthograde endodontic treatment, retreatment and apicectomy were unsuccessful in the management of and infected mandibular right first molar. The periapical radiolucency eventually disappeared following a second orthograde retreatment. Teh second retreatment included 12 months of intracanal calcium hydroxide placement to promote apexification, thus allowing subsequent controlled obturation with gutta percha and AH26. At a 5-year review following completion of treatment, the tooth remained asymptomatic and was in normal function. Orthograde retreatment is a treatment option to manage refractory lesions in teeth that have previously received endodontic treatment, retreatment and apicectomy. Orthograde retreatment using long-term intracanal calcium hydroxide can help promote root-end closure of a resected apex.

  20. Damage to root dentin during retreatment procedures

    NARCIS (Netherlands)

    Shemesh, H.; Roeleveld, A.C.; Wesselink, P.R.; Wu, M.K.

    2011-01-01

    Introduction: The aim of this study was to explore the influence of retreatment procedures on the appearance of defects on the root canal walls. Methods: Two hundred mandibular premolars were divided into 4 groups. One group was left unprepared. The rest of the teeth were prepared with ProTaper file

  1. Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru

    Science.gov (United States)

    López-Moreno, J. I.; Fontaneda, S.; Bazo, J.; Revuelto, J.; Azorin-Molina, C.; Valero-Garcés, B.; Morán-Tejeda, E.; Vicente-Serrano, S. M.; Zubieta, R.; Alejo-Cochachín, J.

    2014-01-01

    We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers are the main source of water for the surrounding lowlands, and melting of these glaciers has triggered several outburst floods. During the 28-year study period, there was a 55% decrease in the surface covered by glaciers and the snowline moved upward in different regions by 93 to 157 m. Moreover, several new lakes formed in the recently deglaciated areas. There was an increase in precipitation during the wet season (October-April) over the 28-year study period. The significant increase in maximum temperatures may be related to the significant glacier retreat in the study area. There were significant differences in the wet season temperatures during El Niño (warmer) and La Niña (colder) years. Although La Niña years were generally more humid than El Niño years, these differences were not statistically significant. Thus, glaciers tended to retreat at a high rate during El Niño years, but tended to be stable or increase during La Niña years, although there were some notable deviations from this general pattern. Climate simulations for 2021 to 2050, based on the most optimistic assumptions of greenhouse gas concentrations, forecast a continuation of climate warming at the same rate as documented here. Such changes in temperature might lead to a critical situation for the glaciers of the Cordillera Huaytapallana, and may significantly impact the water resources, ecology, and natural hazards of the surrounding areas.

  2. Cytoskeletal regulation dominates temperature-sensitive proteomic changes of hibernation in forebrain of 13-lined ground squirrels.

    Directory of Open Access Journals (Sweden)

    Allyson G Hindle

    Full Text Available 13-lined ground squirrels, Ictidomys tridecemlineatus, are obligate hibernators that transition annually between summer homeothermy and winter heterothermy - wherein they exploit episodic torpor bouts. Despite cerebral ischemia during torpor and rapid reperfusion during arousal, hibernator brains resist damage and the animals emerge neurologically intact each spring. We hypothesized that protein changes in the brain underlie winter neuroprotection. To identify candidate proteins, we applied a sensitive 2D gel electrophoresis method to quantify protein differences among forebrain extracts prepared from ground squirrels in two summer, four winter and fall transition states. Proteins that differed among groups were identified using LC-MS/MS. Only 84 protein spots varied significantly among the defined states of hibernation. Protein changes in the forebrain proteome fell largely into two reciprocal patterns with a strong body temperature dependence. The importance of body temperature was tested in animals from the fall; these fall animals use torpor sporadically with body temperatures mirroring ambient temperatures between 4 and 21°C as they navigate the transition between summer homeothermy and winter heterothermy. Unlike cold-torpid fall ground squirrels, warm-torpid individuals strongly resembled the homeotherms, indicating that the changes observed in torpid hibernators are defined by body temperature, not torpor per se. Metabolic enzymes were largely unchanged despite varied metabolic activity across annual and torpor-arousal cycles. Instead, the majority of the observed changes were cytoskeletal proteins and their regulators. While cytoskeletal structural proteins tended to differ seasonally, i.e., between summer homeothermy and winter heterothermy, their regulatory proteins were more strongly affected by body temperature. Changes in the abundance of various isoforms of the microtubule assembly and disassembly regulatory proteins

  3. Up-regulation of Long Non-coding RNA TUG1 in Hibernating Thirteen-lined Ground Squirrels

    Directory of Open Access Journals (Sweden)

    Jacques J. Frigault

    2016-04-01

    Full Text Available Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs (lncRNAs, a group of non-coding transcripts with diverse functions, are differentially expressed during hibernation. In this study, expression levels of lncRNAs H19 and TUG1 were assessed via qRT-PCR in liver, heart, and skeletal muscle tissues of the hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus. TUG1 transcript levels were significantly elevated 1.94-fold in skeletal muscle of hibernating animals when compared with euthermic animals. Furthermore, transcript levels of HSF2 also increased 2.44-fold in the skeletal muscle in hibernating animals. HSF2 encodes a transcription factor that can be negatively regulated by TUG1 levels and that influences heat shock protein expression. Thus, these observations support the differential expression of the TUG1–HSF2 axis during hibernation. To our knowledge, this study provides the first evidence for differential expression of lncRNAs in torpid ground squirrels, adding lncRNAs as another group of transcripts modulated in this mammalian species during hibernation.

  4. Up-regulation of Long Non-coding RNA TUG1 in Hibernating Thirteen-lined Ground Squirrels

    Institute of Scientific and Technical Information of China (English)

    Jacques J. Frigault; Daneck Lang-Ouellette; Pier Morin Jr.

    2016-01-01

    Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs (lncRNAs), a group of non-coding transcripts with diverse functions, are differ-entially expressed during hibernation. In this study, expression levels of lncRNAs H19 and TUG1 were assessed via qRT-PCR in liver, heart, and skeletal muscle tissues of the hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus). TUG1 transcript levels were signifi-cantly elevated 1.94-fold in skeletal muscle of hibernating animals when compared with euthermic animals. Furthermore, transcript levels of HSF2 also increased 2.44-fold in the skeletal muscle in hibernating animals. HSF2 encodes a transcription factor that can be negatively regulated by TUG1 levels and that influences heat shock protein expression. Thus, these observations support the differential expression of the TUG1–HSF2 axis during hibernation. To our knowledge, this study provides the first evidence for differential expression of lncRNAs in torpid ground squirrels, adding lncRNAs as another group of transcripts modulated in this mammalian species during hibernation.

  5. An ANN-Based Synthesis Model for Parallel Coupled Microstrip Lines with Floating Ground-Plane Conductor and Its Applications

    Directory of Open Access Journals (Sweden)

    Yuan Cao

    2016-01-01

    Full Text Available To directly obtain physical dimensions of parallel coupled microstrip lines with a floating ground-plane conductor (PCMLFGPC, an accurate synthesis model based on an artificial neural network (ANN is proposed. The synthesis model is validated by using the conformal mapping technique (CMT analysis contours. Using the synthesis model and the CMT analysis, the PCMLFGPC having equal even- and odd-mode phase velocities can be obtained by adjusting the width of the floating ground-plane conductor. Applying the method, a 7 dB coupler with the measured isolation better than 27 dB across a wide bandwidth (more than 120%, a 90° Schiffman phase shifter with phase deviation ±2.5° and return loss more than 17.5 dB covering 63.4% bandwidth, and a bandpass filter with completely eliminated second-order spurious band are implemented. The performances of the current designs are superior to those of the previous components configured with the PCMLFGPC.

  6. A three-dimensional full Stokes model of the grounding line dynamics: effect of a pinning point beneath the ice shelf

    Directory of Open Access Journals (Sweden)

    L. Favier

    2012-01-01

    Full Text Available The West Antarctic ice sheet is confined by a large area of ice shelves, fed by inland ice through fast flowing ice streams. The dynamics of the grounding line, which is the line-boundary between grounded ice and the downstream ice shelf, has a major influence on the dynamics of the whole ice sheet. However, most ice sheet models use simplifications of the flow equations, as they do not include all the stress components, and are known to fail in their representation of the grounding line dynamics. Here, we present a 3-D full Stokes model of a marine ice sheet, in which the flow problem is coupled with the evolution of the upper and lower free surfaces, and the position of the grounding line is determined by solving a contact problem between the shelf/sheet lower surface and the bedrock. Simulations are performed using the open-source finite-element code Elmer/Ice within a parallel environment. The model's ability to cope with a curved grounding line and the effect of a pinning point beneath the ice shelf are investigated through prognostic simulations. Starting from a steady state, the sea level is slightly decreased to create a contact point between a seamount and the ice shelf. The model predicts a dramatic decrease of the shelf velocities, leading to an advance of the grounding line until both grounded zones merge together, during which an ice rumple forms above the contact area at the pinning point. Finally, we show that once the contact is created, increasing the sea level to its initial value does not release the pinning point and has no effect on the ice dynamics, indicating a stabilising effect of pinning points.

  7. Deriving mechanisms and thresholds for cliff retreat in soft-rock cliffs under changing climates: Rapidly retreating cliffs of the Suffolk coast, UK

    Science.gov (United States)

    Brooks, S. M.; Spencer, T.; Boreham, S.

    2012-06-01

    Understanding changing thresholds and mechanisms for retreat in soft rock cliffs is important under changing climates. This can be achieved through combining detailed field observation, long-term process and morphological monitoring and numerical modelling. The cliffs of the Suffolk coast, southern North Sea have exhibited long-term (1883-2010) recession rates of 3.5 m a- 1, rising to 4.7 m a- 1 in the period 1993-2010. Annual to biannual ground survey data, and the application of GIS techniques to digitised records of changing shoreline position from historic maps and aerial photography, reveal considerable decadal-scale variations in cliff recession, within which are nested inter-annual fluctuations in rates of retreat. Archival datasets on significant periods of onshore winds and their interaction with high water levels (including the incidence of storm surges) and rainstorm events are used to determine thresholds for cliff base erosion and its propagation upwards through the cliff profile. In addition, the ‘GEO-Slope' dynamic coupled hydrology-stability model is used to establish thresholds for cliff face failures driven by variations in rainfall inputs. Retreat mechanisms are complex, governed by cliff geology, both as a primary control on suction loss and through its interaction with basal marine conditions. The study allows a general model of cliff retreat for soft rock cliffs to be put forward, whereby a resistant basal platform is overlain by more erodible, weakly and moderately cemented sands and gravels. In this model, the varying balance between marine and terrestrial forcing factors are reflected in low ( 7 m a- 1) modes of cliff retreat.

  8. Retreatments after multifocal intraocular lens implantation: an analysis

    Science.gov (United States)

    Gundersen, Kjell Gunnar; Makari, Sarah; Ostenstad, Steffen; Potvin, Rick

    2016-01-01

    Purpose To determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL) implantation and to evaluate the methods and clinical outcomes of retreatment. Patients and methods A retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients. Results The multifocal retreatment rate was 10.8% (45/416 eyes). The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01). The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152) and bilateral trifocal (6.9%, 14/202) IOLs, was not statistically significantly different (P=0.12). In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time. Conclusion Complaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option. PMID:27041983

  9. Retreatments after multifocal intraocular lens implantation: an analysis

    Directory of Open Access Journals (Sweden)

    Gundersen KG

    2016-03-01

    Full Text Available Kjell Gunnar Gundersen,1 Sarah Makari,2 Steffen Ostenstad,1 Rick Potvin2 1Ifocus Eye Clinic, Haugesund, Norway; 2Science in Vision, Akron, NY, USA Purpose: To determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL implantation and to evaluate the methods and clinical outcomes of retreatment.Patients and methods: A retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients.Results: The multifocal retreatment rate was 10.8% (45/416 eyes. The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01. The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152 and bilateral trifocal (6.9%, 14/202 IOLs, was not statistically significantly different (P=0.12. In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time.Conclusion: Complaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option. Keywords: piggyback IOL, Sulcoflex, toric, STAAR, symptoms, astigmatism

  10. Brief Analysis on the Theory of Fault Line Selection of Single Phase Grounding in Small Current Neutral Grounding System%浅析小电流接地系统单相接地故障选线原理

    Institute of Scientific and Technical Information of China (English)

    邢威

    2015-01-01

    文章纵观小电流接地选线的发展历史,简要概括了小电流接地系统发生单相接故障时系统基本特征,分析了几种选线原理的特点,提出了尚需解决的问题,最后给出了分析结论。%In the view of the history of small current grounding fault line selection, the basic features of small current grounding system when single phase grounding failure occurs were briefly summarized, and several characteristics of fault line selection were analyzed, the problems need to be solved were proposed, and the analysis of ifndings was given.

  11. Detecting the single line to ground short circuit fault in the submarine’s power system using the artificial neural network

    Directory of Open Access Journals (Sweden)

    Behniafar Ali

    2013-01-01

    Full Text Available The electric marine instruments are newly inserted in the trade and industry, for which the existence of an equipped and reliable power system is necessitated. One of the features of such a power system is that it cannot have an earth system causing the protection relays not to be able to detect the single line to ground short circuit fault. While on the other hand, the occurrence of another similar fault at the same time can lead to the double line fault and thereby the tripping of relays and shortening of vital loads. This in turn endangers the personals' security and causes the loss of military plans. From the above considerations, it is inferred that detecting the single line to ground fault in the marine instruments is of a special importance. In this way, this paper intends to detect the single line to ground fault in the power systems of the marine instruments using the wavelet transform and Multi-Layer Perceptron (MLP neural network. In the numerical analysis, several different types of short circuit faults are simulated on several marine power systems and the proposed approach is applied to detect the single line to ground fault. The results are of a high quality and preciseness and perfectly demonstrate the effectiveness of the proposed approach.

  12. One clinician's journey - a retreat from 'the front line'.

    Science.gov (United States)

    Murchie, B

    2017-01-27

    Whether the clinician has recently qualified or graduation day is a distant memory, it is important for him/her to be aware of the alternative options available outside of the general practice setting as these are not always fully explained. It is essential that one enjoys their career choice when even a brief consideration is given to the length of time that one will spend at work and thinking about work, including the additional hours spent in the workplace for countless other reasons. The author worked as a general dental practitioner for several years at different practices. However, dissatisfaction with the daily routine eventually led to a crossroads and a new chapter of his professional career blossomed at a later stage in life. This article is aimed at undergraduates and postgraduates alike, so that others can learn from the author's unconventional career pathway.

  13. Glacial retreat in the Amundsen Sea sector, West Antarctica - first cosmogenic evidence from central Pine Island Bay and the Kohler Range

    Science.gov (United States)

    Lindow, Julia; Castex, Marion; Wittmann, Hella; Johnson, Joanne S.; Lisker, Frank; Gohl, Karsten; Spiegel, Cornelia

    2014-08-01

    The Amundsen Sea Embayment of West Antarctica hosts one of the most rapidly changing sectors of the West Antarctic Ice Sheet. With the fastest-flowing ice streams in Antarctica, the region around Pine Island Bay is characterized by rapid ice-sheet thinning and grounding-line retreat. Published surface-exposure data are limited to a few isolated nunataks making it difficult to assess the long-term deglacial history of the area. To address this, we correlate existing records of lateral ice-stream retreat from marine sediment cores with onshore glacial thinning in two key areas of eastern Marie Byrd Land: the Kohler Range and Pine Island Bay. Our 10Be surface-exposure ages are the first from the isolated Kohler Range and show that the nunataks there became ice-free between 8.6 and 12.6 ka. This implies a minimum long-term average thinning rate of 3.3 ± 0.3 cm/yr, which is one order of magnitude lower than recent rates based on satellite data. We also present pre- to early Holocene 10Be surface-exposure ages from two islands located approximately 80 km downstream of the Pine Island Glacier ice-shelf front to constrain the lateral deglacial history in the Pine Island Bay area. This study provides insight into the significance of local ice sheet variations and suggests that the post-LGM history in the Amundsen Sea sector was characterized by glacial thinning as well as lateral retreat in pre- to early Holocene times.

  14. FISHING GROUND, CACTH COMPOSITION, HOOK RATE AND LENGTH DISTRIBUTION OF BILLFISHES CAUGHT BY TUNA LONG LINE IN INDIAN OCEAN

    Directory of Open Access Journals (Sweden)

    Fathur Rochman

    2013-12-01

    Full Text Available Billfishes area by cacth of tuna long line vessels in Indian Ocean. Billfish are consist of swordfish Xiphias gladius, black marlin Makaira indica, indo facific blue marlin Makaira mazara, stripe marlin Tetrapturus audax, indo facific sailfish Istiophorus platypterus and shortbill spearfish Tetrapturus angustirostris. Besides that, billfishes also have important economic value compared with tuna as an exsported species such as swordfish and marlin. To optimize the catch of billfishes in Indian Ocean, data and information of potential fishing ground, size and catch composition of this species are needed. The billfishes cacth composition collected in 2011 were dominated by 45% swordfish, 20% black marlin, 19% blue marlin,9% short bill spearfish, 6% sailfish and 1%stripe marlin. The billfishes size range which were caught between 60 - 280 cm LJFL (Lower Jaw Fork Length. The sword fish average length was 150 cm, blue marlin 197 cm, black Marlin 189 cm, sailfish 150cm ,short bill spearfish 144 cm and stripe marlin159 cm. From this observation, it was found that most of billfishes caught were in mature.

  15. A Novel Protection Method for Single Line-to-Ground Faults in Ungrounded Low-Inertia Microgrids

    Directory of Open Access Journals (Sweden)

    Liuming Jing

    2016-06-01

    Full Text Available This paper proposes a novel protection method for single line-to-ground (SLG faults in ungrounded low-inertia microgrids. The proposed method includes microgrid interface protection and unit protection. The microgrid interface protection is based on the difference between the zero-sequence voltage angle and the zero-sequence current angle at the microgrid interconnection transformer for fast selection of the faulty feeder. The microgrid unit protection is based on a comparison of the three zero-sequence current phase directions at each junction point of load or distributed energy resources. Methods are also included to locate the minimum fault section. The fault section location technology operates according to the coordination of microgrid unit protection. The proposed method responds to SLG faults that may occur in both the grid and the microgrid. Simulations of an ungrounded low-inertia microgrid with a relay model were carried out using Power System Computer Aided Design (PSCAD/Electromagnetic Transients including DC (EMTDC.

  16. On the resonance effects due to ground wires in transmission lines with non-uniform soil conductivity and non-uniform tower resistances

    Energy Technology Data Exchange (ETDEWEB)

    Faria, J.A. B. (Centro de Electrotecnia da Univ. Tecnica de Lisboa, Dept. of Electrical Engineering, Inst. Superior Tecnico, 1096 Lisboa Codex (PT))

    1992-01-01

    High frequency resonance effects due to shield wires grounding may affect carrier transmission performance at the vicinity of certain critical frequencies. In this paper the authors investigate if non-uniformities in soil conductivity and in tower footing resistances along the power line may lead to the suppression of such resonance effects. The simulation results the authors have obtained point towards a negative conclusion.

  17. Sedimentology and chronology of the advance and retreat of the last British-Irish Ice Sheet on the continental shelf west of Ireland

    Science.gov (United States)

    Peters, Jared L.; Benetti, Sara; Dunlop, Paul; Ó Cofaigh, Colm; Moreton, Steven G.; Wheeler, Andrew J.; Clark, Christopher D.

    2016-05-01

    The last British-Irish Ice Sheet (BIIS) had extensive marine-terminating margins and was drained by multiple large ice streams and is thus a useful analogue for marine-based areas of modern ice sheets. However, despite recent advances from investigating the offshore record of the BIIS, the dynamic history of its marine margins, which would have been sensitive to external forcing(s), remain inadequately understood. This study is the first reconstruction of the retreat dynamics and chronology of the western, marine-terminating, margin of the last (Late Midlandian) BIIS. Analyses of shelf geomorphology and core sedimentology and chronology enable a reconstruction of the Late Midlandian history of the BIIS west of Ireland, from initial advance to final retreat onshore. Five AMS radiocarbon dates from marine cores constrain the timing of retreat and associated readvances during deglaciation. The BIIS advanced without streaming or surging, depositing a bed of highly consolidated subglacial traction till, and reached to within ˜20 km of the shelf break by ˜24,000 Cal BP. Ice margin retreat was likely preceded by thinning, grounding zone retreat and ice shelf formation on the outer shelf by ˜22,000 Cal BP. This ice shelf persisted for ≤2500 years, while retreating at a minimum rate of ˜24 m/yr and buttressing a >150-km long, 20-km wide, bathymetrically-controlled grounding zone. A large (˜150 km long), arcuate, flat-topped grounding-zone wedge, termed here the Galway Lobe Grounding-Zone Wedge (GLGZW), was deposited below this ice shelf and records a significant stillstand in BIIS retreat. Geomorphic relationships indicate that the BIIS experienced continued thinning during its retreat across the shelf, which led to increased topographic influence on its flow dynamics following ice shelf break up and grounding zone retreat past the GLGZW. At this stage of retreat the western BIIS was comprised of several discrete, asynchronous lobes that underwent several readvances

  18. Semantics versus statistics in the retreat from locative overgeneralization errors.

    Science.gov (United States)

    Ambridge, Ben; Pine, Julian M; Rowland, Caroline F

    2012-05-01

    The present study investigated how children learn that some verbs may appear in the figure-locative but not the ground-locative construction (e.g., Lisa poured water into the cup; *Lisa poured the cup with water), with some showing the opposite pattern (e.g., *Bart filled water into the cup; Bart filled the cup with water), and others appearing in both (Lisa sprayed water onto the flowers; Lisa sprayed the flowers with water). Grammatical acceptability judgments were obtained for the use of each of 142 locative verbs (60 for children) in each sentence type. Overall, and for each age group individually, the judgment data were best explained by a model that included ratings of the extent to which each verb exhibits both the broad- and narrow-range semantic properties of the figure- and ground-locative constructions (relating mainly to manner and end-state respectively; Pinker, 1989) and the statistical-learning measure of overall verb frequency (entrenchment; Braine & Brooks, 1995). A second statistical-learning measure, frequency in each of the two locative constructions (pre-emption; Goldberg, 1995), was found to have no additional dissociable effect. We conclude by drawing together various theoretical proposals to arrive at a possible account of how semantics and statistics interact in the retreat from overgeneralization.

  19. A Novel High-Frequency Voltage Standing-Wave Ratio-Based Grounding Electrode Line Fault Supervision in Ultra-High Voltage DC Transmission Systems

    Directory of Open Access Journals (Sweden)

    Yufei Teng

    2017-03-01

    Full Text Available In order to improve the fault monitoring performance of grounding electrode lines in ultra-high voltage DC (UHVDC transmission systems, a novel fault monitoring approach based on the high-frequency voltage standing-wave ratio (VSWR is proposed in this paper. The VSWR is defined considering a lossless transmission line, and the characteristics of the VSWR under different conditions are analyzed. It is shown that the VSWR equals 1 when the terminal resistance completely matches the characteristic impedance of the line, and when a short circuit fault occurs on the grounding electrode line, the VSWR will be greater than 1. The VSWR will approach positive infinity under metallic earth fault conditions, whereas the VSWR in non-metallic earth faults will be smaller. Based on these analytical results, a fault supervision criterion is formulated. The effectiveness of the proposed VSWR-based fault supervision technique is verified with a typical UHVDC project established in Power Systems Computer Aided Design/Electromagnetic Transients including DC(PSCAD/EMTDC. Simulation results indicate that the proposed strategy can reliably identify the grounding electrode line fault and has strong anti-fault resistance capability.

  20. Summary of the RHIC Retreat 2008

    Energy Technology Data Exchange (ETDEWEB)

    Pilat,F.; Brennan, M.; Brown, K.; Fischer, W.; Montag, C.

    2008-08-01

    The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE.

  1. Retreat mining with integrated dirt stowing

    Energy Technology Data Exchange (ETDEWEB)

    Round, C.

    1979-12-01

    The circumstances that led ultimately to the design and development of the integrated stowing techniques on retreat faces at Park Mill Colliery in the Barnsley Area of the National Coal Board are discussed. The problems met during the design and implementation stages are dealt with in some detail, as are associated activities such as truss roof bolting which has enabled the system to be an unqualified success. Results achieved so far and an indication of the benefits that have accrued from the working of the system at Park Mill are given with implications for wider use in the mining industry.

  2. Development of Speed Car Crossing the Obstacle on the Ground Line%过障碍物地线飞车的研制

    Institute of Scientific and Technical Information of China (English)

    朱理宏

    2015-01-01

    The transmission line maintenance repair work is an important constituent part of the line oper-ation and maintenance work , it is essential to eliminate the line defects and ensure safe and stable opera-tion for the line .When the defect occurs on the ground line , how to cross the obstacles on the ground line in time to eliminate the defects has been one of the major research topics for every company of operation and maintenance for lines .This article describes the principle , the development process and the key technology of speed car crossing the obstacles on the ground line , and it has great value for the elimina-tion of similar defects in the future .%输电线路检修工作是线路运维工作的一个重要工作组成部分,对于消除线路缺陷,确保线路安全稳定运行至关重要。当缺陷出现在地线上的时候,如何跨越地线上的障碍物及时消缺一直是各线路运行维护单位主要的研究课题之一。文章介绍了过障碍物地线飞车研制的原理、研制过程及关键技术,对以后类似缺陷的消除具有比较好的应用价值。

  3. Development of the Spring-Hook Grounding Line of EHV/UHV Transmission Line%超(特)高压线路弹压式钩型接地线的研制

    Institute of Scientific and Technical Information of China (English)

    晏节晋; 张振威

    2015-01-01

    An important measure is that to hang grounding lines to protect electric operators from electric shock injury in the interruption maintenance of transmission lines .There are some difficulties and security risks in the process of the use of common grounding lines , especially even worse in EHV/UHV transmis-sion line .But this spring-hook grounding line is more simple and convenient , more efficient and safer in the process of hanging and removing .%输电线路停电检修时,一项重要保护措施就是挂设接地线,以保证检修人员在检修过程中免遭触电伤害。而比较常见的接地线在使用过程中存在一定的困难和安全隐患,特别是在超(特)高压输电线路上,尤为明显,而研制的弹压式钩型接地线在挂设、拆除过程中简单方便、工作效率较高、安全性大大提高。

  4. Asbestos fibres in the lungs of an American mechanic who drilled, riveted, and ground brake linings: a case report and discussion.

    Science.gov (United States)

    Finkelstein, Murray M

    2015-05-01

    In North America and Europe, the use of asbestos in friction products was discontinued before the end of the 20th century. In the developing world, the use of asbestos-containing friction products continues. In 2010, Cely-Garcia and colleagues (Cely-Garcia et al., 2012) sampled three brake repair shops located in Bogota, Colombia. Both asbestos and non-asbestos containing brake linings were sold separately or attached to a shoe. When brake linings are sold separated from the shoe, they must be manipulated to attach them to the shoe before installation. The process starts with the removal of the old brake shoe from the vehicle's brake drum. If the existing brake shoe is to be reused, the old lining needs to be removed and the old shoe must be ground to prepare it for a new lining. Riveting requires drilling holes in the linings and shoes and before installing rivets, the lining must be countersunk. The borders of the lining are bevelled. On some occasions, the entire exposed surface of the lining is ground to make it thinner. Once attached to the shoe, the edges of brake linings may extend beyond the shoe. In this case, it is necessary to cut or grind the edges to match the lining to the shoe before bevelling or grinding. The authors reported that 'the sampling results indicate that the brake mechanics sampled are exposed to extremely high asbestos concentrations (i.e. based on transmission electron microscopy counts), suggesting that this occupational group could be at excess risk of asbestos-related diseases'.

  5. Factors contributing to the surgical retreatment of mandibular fractures

    Directory of Open Access Journals (Sweden)

    João Gualberto de Cerqueira Luz

    2013-06-01

    Full Text Available The purpose of this retrospective study was to evaluate contributing factors in patients requiring surgical retreatment of mandibular fractures. Of all the patients with mandibular fractures who were treated using internal fixation at a trauma hospital over a seven-year period, 20 patients (4.7% required a second surgery and thus composed the “reoperated” group. The control group comprised 42 consecutive patients with mandibular fractures who were treated at the same clinic and who healed without complications. Medical charts were reviewed for gender, age, substance abuse history, dental condition, etiology, location of fracture, degree of fragmentation, fracture exposure, teeth in the fracture line, associated facial fractures, polytrauma, time elapsed between trauma and initial treatment, surgical approach and fixation system. Statistical analyses were performed using the Statistical Package for Social Sciences (SPSS version 20.0; descriptive statistics and the chi-squared test were used to determine differences between groups. Significant differences in substance abuse (p = 0.006, dental condition (p < 0.001, location of fracture (p = 0.010, degree of fragmentation (p = 0.003 and fracture exposure (p < 0.001 were found. With regard to age and time elapsed between trauma and initial treatment, older patients (31.4 years, SD = 11.1 and a delay in fracture repair (19.1 days, SD = 18.7 were more likely to be associated with reoperation. It was concluded that substance abuse, age, dental condition, location of fracture, degree of fragmentation, fracture exposure and the time between trauma and initial treatment should be considered contributing factors to the occurrence of complications that require surgical retreatment of mandibular fractures.

  6. Selective mobilization of saturated fatty acids in isolated adipocytes of hibernating 13-lined ground squirrels Ictidomys tridecemlineatus.

    Science.gov (United States)

    Price, Edwin R; Armstrong, Christopher; Guglielmo, Christopher G; Staples, James F

    2013-01-01

    Fatty acids are not mobilized from adipocyte triacylglycerols uniformly but rather some are preferentially mobilized while others are preferentially retained. In many vertebrate species, the pattern of differential mobilization is determined by the physical and chemical properties of each fatty acid. Fatty acids with shorter chains and more double bonds tend to be more readily mobilized than others, a pattern observed both in whole-animal studies and in isolated adipocytes. Several hibernating species seem to break this pattern, however, and retain 18:2ω6 (linoleic acid) while mobilizing saturated fatty acids such as 18:0. We sought to confirm this pattern in adipocytes of a hibernator, the 13-lined ground squirrel Ictidomys tridecemlineatus, and to investigate mobilization patterns for the first time at hibernation temperature. We isolated adipocytes from summer active and winter torpid squirrels and incubated them with 1 μM norepinephrine at 4°C (7 h) and 37°C (90 min). We measured the proportion of each fatty acid in the adipose tissue and in the buffer at the end of incubation. Patterns of mobilization were similar in both seasons and incubation temperatures. Saturated fatty acids (18:0 and 16:0) were highly mobilized relative to the average, while some unsaturated fatty acids (notably, 18:1ω9 and 18:2ω6) were retained. We conclude that hibernators have unique mechanisms at the level of adipose tissue that preferentially mobilize saturated fatty acids. Additionally, we found that adipocytes from hibernating squirrels produced more glycerol than those from summer squirrels (regardless of temperature), indicating a higher lipolytic capacity in hibernating squirrels.

  7. GPCR Retreat 2012: timing is everything.

    Science.gov (United States)

    Chidiac, Peter; Hébert, Terence E

    2013-06-01

    In London, Ontario, the 13th Annual Joint meeting of the Great Lakes GPCR Retreat and the Club des Récepteurs à Sept Domaines Transmembranaires (known simply as the GPCR Retreat) was held on 17-19 October 2012, organized by Steve Ferguson and Peter Chidiac. This meeting gathered together a core group of investigators from Michigan, Ontario and Québec and has steadily increased its attendance in both the eastern (Europe) and western (USA, Canada) directions. This year's buzz naturally centered around the Nobel Prize in Chemistry, which was won the week before by Brian Kobilka and Robert Lefkowitz for their work on receptor structure and function. Michel Bouvier provided a heartfelt tribute to one of the attendees, Marc Caron, a pioneer in the GPCR field, has made many contributions to the work that led to this year's Nobel Prize. The meeting featured interesting sessions on the physiological roles of GPCRs in the nervous system, circadian biology and cancer, dealing at the cellular and molecular level with GPCR, G protein and effector structure and function, regulation and trafficking--with an overall focus on how to move molecular pharmacology in vivo.

  8. Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period.

    Science.gov (United States)

    Klages, Johann P; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Smith, James A; Graham, Alastair G C; Nitsche, Frank O; Frederichs, Thomas; Jernas, Patrycja E; Gohl, Karsten; Wacker, Lukas

    2017-01-01

    Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5-19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2-3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period.

  9. Slowing down the retreat of the Morteratsch glacier, Switzerland, by artificially produced summer snow

    Science.gov (United States)

    Oerlemans, Johannes; Keller, Felix; Haag, Martin

    2017-04-01

    Many large valley glaciers in the world are retreating at historically unprecedented rates. Also in the Alps, where warming over the past decades has been more than twice as large as the global mean, all major glaciers have retreated over distances of several kilometers over the past hundred years. The Morteratsch Glacier, Pontresina, Switzerland, is a major touristic attraction. Due to strong retreat the lowest part of the glacier is getting out of sight from the gravel road that provided direct access to the glacier front. The Community of Pontresina has commissioned a preparatory study to find out if it is possible to slow down the retreat of the Morteratsch Glacier in an environmentally friendly way. In this article we report on the outcome of such a study, based on a modelling approach. Our analysis is based on a 20- year weather station record from the lower part of the glacier, combined with calculations with an ice flow model. This model has been carefully calibrated against the historical glacier length record, to ensure an optimal initial state for projections into the future. We arrive at the conclusion that producing summer snow in the ablation zone over a larger area (typically 0.5 to 1 km ^2) is the best option, and may have a significant effect on the rate of retreat on a timescale of decades. We consider three scenarios of climate change: (i) no change, (ii) a rise of the Equilibrium Line Altitude (ELA) by 1 m/yr, and (iii) a rise of the ELA by 2 m/yr. Projections of glacier length are done until the year 2100. It takes about 10 years before snow deposition in the higher ablation zone starts to affect the position of the glacier snout. The difference in glacier length between the snow and no-snow experiments becomes 400 to 500 m within two decades.

  10. Academic Writing Retreat: A Time for Rejuvenated and Focused Writing

    Science.gov (United States)

    Swaggerty, Elizabeth A.; Atkinson, Terry S.; Faulconer, Johna L.; Griffith, Robin R.

    2011-01-01

    The purpose of this article is to describe the impact of a three-day academic writing retreat on the writing lives of four female university faculty members. Goals of the retreat included rejuvenating their writing lives, focusing their research agendas, improving their writing, and engaging in concentrated blocks of writing and collaborative…

  11. Writing Retreat as Structured Intervention: Margin or Mainstream?

    Science.gov (United States)

    Murray, Rowena; Newton, Mary

    2009-01-01

    Academics across the world face increasing pressure to publish. Research shows that writing retreats have helped by creating dedicated writing time and building collegiality. A new form of "structured" writing retreat was created to increase its impact by taking a community of practice approach. This paper reports on an evaluation, funded by the…

  12. Academic Writing Retreat: A Time for Rejuvenated and Focused Writing

    Science.gov (United States)

    Swaggerty, Elizabeth A.; Atkinson, Terry S.; Faulconer, Johna L.; Griffith, Robin R.

    2011-01-01

    The purpose of this article is to describe the impact of a three-day academic writing retreat on the writing lives of four female university faculty members. Goals of the retreat included rejuvenating their writing lives, focusing their research agendas, improving their writing, and engaging in concentrated blocks of writing and collaborative…

  13. Modelling Waterfall Retreat in Heterogenous Bedrock

    Science.gov (United States)

    Attal, M.; Hodge, R. A.; Williams, R.; Baynes, E.

    2016-12-01

    Bedrock rivers are the mediators of environmental change through mountainous landscapes. In response to an increase in uplift rate for example, a "knickpoint" (often materialised as a waterfall) will propagate upstream, separating a domain downstream where the river and its adjacent hillslopes have steepened in response to the change from a "relict" domain upstream which is adjusted to the conditions before the change (Crosby and Whipple 2006). Many studies assume that knickpoint propagation rate scales with drainage area, based on the stream power theory. However, recent studies in a range of locations have found no obvious relationship between knickpoint retreat rate and drainage area, potentially resulting from the stream power law neglecting (i) the influence of sediment on the processes associated with waterfall migration and (ii) thresholds for bedrock detachment (Cook et al. 2013; Mackey et al. 2014; DiBiase et al. 2015; Baynes et al. 2015; Brocard et al. 2016). In this study, we develop a 1D model of waterfall retreat in horizontally bedded bedrock with varying joint spacing. In the model, knickpoint migration is based on two rules: a waterfall will start migrating once the threshold flow depth (a function of knickpoint height and joint spacing) has been exceeded (Lamb and Dietrich 2009), and the migration rate will then be a function of the water-depth-to-waterfall-height ratio, based on experimental results by Baynes (2015). Using a hydrograph based on a Poisson rectangular pulse rainfall simulator (Tucker and Bras 2001), we demonstrate the importance of structure in controlling the speed at which waterfalls migrate but also their number and the length over which they are distributed (Fig. 1). The model is applied to the Jökulsá á Fjöllum, NE Iceland, where rapid migration of waterfalls as a result of discrete events has been identified (Baynes et al. 2015), using new constraints on joint spacing derived from high resolution lidar survey of the gorge

  14. Moisture Analysis of a Squall Line Case Based on Precipitable Water Vapor Data from a Ground-Based GPS Network in the Yangtze River Delta

    Institute of Scientific and Technical Information of China (English)

    DING Jincai; YANG Yinming; YE Qixin; HUANG Yan; MA Xiaoxing; MA Leiming; Y.R.GUO

    2007-01-01

    A squall line swept eastward across the area of the Yangtze River Delta and produced gusty winds and heavy rain from the afternoon to the evening of 24 August 2002. In this paper, the roles of moisture in the genesis and development of the squall line were studied. Based on the precipitable water vapor (PWV) data from a ground-based GPS network over the Yangtze River Delta in China, plus data from a Pennsylvania State University/National Atmospheric Center (PSU/NCAR) mesoscale model (MM5) simulation, initialized by three-dimensional variational (3D-VAR) assimilation of the PWV data, some interesting features are revealed. During the 12 hours prior to the squall line arriving in the Shanghai area, a significant increase in PWV indicates a favorable moist environment for a squall line to develop. The vertical profile of the moisture illustrates that it mainly increased in the middle levels of the troposphere, and not at the surface. Temporal variation in PWV is a better precursor for squall line development than other surface meteorological parameters. The characteristics of the horizontal distribution of PWV not only indicated a favorable moist environment, but also evolved a cyclonic wind field for a squall line genesis and development. The "+2 mm" contours of the three-hourly PWV variation can be used successfully to predict the location of the squall line two hours later.

  15. Stepped Fault Line Selection Method Based on Spectral Kurtosis and Relative Energy Entropy of Small Current to Ground System

    Directory of Open Access Journals (Sweden)

    Xiaowei Wang

    2014-01-01

    Full Text Available This paper proposes a stepped selection method based on spectral kurtosis relative energy entropy. Firstly, the length and type of window function are set; then when fault occurs, enter step 1: the polarity of first half-wave extremes is analyzed; if the ratios of extremes between neighboring lines are positive, the bus bar is the fault line, else, the SK relative energy entropies are calculated, and then enter step 2: if the obtained entropy multiple is bigger than the threshold or equal to the threshold, the overhead line of max entropy corresponding is the fault line, if not, enter step 3: the line of max entropy corresponding is the fault line. At last, the applicability of the proposed algorithm is presented, and the comparison results are discussed.

  16. Engineering Calculation Method of Electromagnetic Effect on Oil/Gas Pipelines from 1 000 kV AC Transmission Line Having Single-phase Ground Fault

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wenliang; JIANG Jun; GUO Jian; LU Jiayu

    2012-01-01

    There will be more and more AC transmission lines near oil/gas pipelines in the future.So in order to determine the safe distance between them,simple and effective methods are required for engineers to efficiently evaluate the electromagnetic effect on oil/gas pipelines due to faults of AC transmission lines.In this paper,an easily handled fitting formula is obtained based on multiple calculation results,which is the maximum voltage on the pipeline anticorrosive coating produced by 1 000 kV AC transmission line under single phase ground fault.Although the calculation results obtained from the fitting formula differ from those gained by precise calculation with softwares,the verification of the formula shows that it is applicable for engineering calculation.This research could be applied to evaluate the electromagnetic effect of 1 000 kV AC transmission line under single-phase ground fault on nearby pipelines,as well as to determine the safe distance or the maximum parallel length.

  17. Student Leadership Retreat Focusing on a Commitment to Excellence

    Science.gov (United States)

    Traynor, Andrew P.; Sorensen, Todd D.

    2009-01-01

    Objective To design and evaluate a student leadership retreat focused on: leadership regardless of position or title, the need for passionate commitment to excellence, the importance of teamwork, and the value of self-reflection. Design Students in their second, third, and fourth year of a doctor of pharmacy (PharmD) program were invited to participate in an off-campus leadership retreat that combined organized learning activities and social/networking opportunities. Retreat content utilized didactic, experiential, and self-directed learning activities. Assessment Forty-two students participated in the retreat and were surveyed pre- and post-retreat. A student-led group evaluation and course evaluations were also utilized. Responses on the post-retreat evaluation suggested an increased belief in their ability to influence change and an enhanced awareness of the role of self-reflection in creating excellence in the profession. Conclusion An off-campus overnight retreat has value in challenging student perceptions about leadership and promoting reflection on their personal role in leading change within the profession Continued exploration and development of this format is warranted for commitment to excellence programming and also for additional leadership topics and audiences. PMID:19564991

  18. Dissecting the Power Sources of Low-Luminosity Emission-Line Galaxy Nuclei via Comparison of HST-STIS and Ground-Based Spectra

    Science.gov (United States)

    Constantin, Anca; Shields, Joseph C.; Ho, Luis C.; Barth, Aaron J.; Filippenko, Alexei V.; Castillo, Christopher A.

    2015-12-01

    Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ≈ 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  19. DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, Anca; Castillo, Christopher A. [Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22807 (United States); Shields, Joseph C. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Barth, Aaron J. [Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

    2015-12-01

    Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ≈ 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude.

  20. Pressure-Induced Shifts of R, R', and B Line-Groups and Ground-State Zero-Field-Splitting of Ruby

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; CHEN Ju-Rong

    2005-01-01

    By means of improved ligand-field theory, the "pure electronic" presure-induced shifts (PS's) and the PS's due to electron-phonon interaction (EPI) of the R1, R2, B1, B2, B3, and R'3 lines and the ground-state zero-field-splitting of ruby have been uniformly calculated. The calculation results are in very good agreement with all the experimental data. At normal pressure, ruby is a crystal with very strong crystal field. Thus, the admixture of |t22 (3T1)e4T2> and |t3 2 2 E> bases in the wavefunction of R1 level of ruby is small at normal pressure, and it gradually decreases with increasing pressure, which causes the R1-line PS of ruby to monotonously red shift with approximate linearity. The combined effect of the pure electronic PS of R1 line and the PS of R1 line due to EPI gives rise to the total PS of R1 line. The analyses and comparisons among the features of R1-line PS's of three laser crystals (ruby, GSGG:Cr3+ and GGG:Cr3+ ) have been made, and the origin of their difference has been revealed.

  1. Climate Change, Glacier Retreat and Sediment Waves: Evidences from Fans in the Fox Glacial valley (New Zealand) and Analogical Modeling

    Science.gov (United States)

    Gomez, C. A.; Purdie, H.

    2015-12-01

    As global climate continues warm, mountain environments are changing, and rates of glacial retreat are unprecedented. The hydrologic implications of this rapid ice retreat and changing climate conditions have been the focus of numerous studies, but the consequent effects on the sediment cascade in valleys and tributaries has received considerably less attention. In the present study, we investigated the role of glacial recession on sediment mobilization and deposition in a mountain valley catchment at Fox Glacier, New Zealand. In particular, we analyze the role of glacier recession on the formation of sediment fans in the main valley. Emphasis was put on the role of sediment, impounded by the glacier in side tributaries, becoming rapidly available for remobilization as the glacier retreats. The method is based on field observations, and measurements using high resolution GNSS (Trimble R8 survey grade differential GNSS) and photogrammetric methods using Structure from Motion based on ground-, helicopter- and UAV- photographs. Field observations were conducted in the period 2014 - 2015, and have been complimented with analogic modeling in the laboratory, in order to comprehend the processes driving rapid fan formation. The analogic model reproduced the retreat of the glacier and the response of a tributary, with simulations for both glaciated and de-glaciated conditions. For similar hydrologic and slope parameters, the fans created after glacial retreat have shown an acceleration in their formation of up to 12 times compared to fanes created without glacial influence. Field observations within the period 2013 - 2015 of Straight Creek Fan (Fox Valley, New Zealand) have confirmed laboratory simulations, with the fan growing to a radius superior to 200 m and a valley-long width superior to 450 m. As glaciers continue to retreat, it can be expected that sediment surges will occur in affected valleys, without the requirements of other forcing like earthquake or extreme

  2. Paludification and forest retreat in northern oceanic environments.

    Science.gov (United States)

    Crawford, R M M; Jeffree, C E; Rees, W G

    2003-01-01

    Examination of temperature variations over the past century for Europe and the Arctic from northern Norway to Siberia suggests that variations in the North Atlantic Oscillation are associated with an increase in oceanicity in certain maritime regions. A southward depression of the tree line in favour of wet heaths, bogs and wetland tundra communities is also observed in northern oceanic environments. The physiological basis for this change in ecological succession from forest to bog is discussed in relation to the long-term effects of flooding on tree survival. The heightened values currently detected in the North Atlantic Oscillation Index, together with rising winter temperatures, and increased rainfall in many areas in northern Europe, presents an increasing risk of paludification with adverse consequences for forest regeneration, particularly in areas with oceanic climates. Climatic warming in oceanic areas may increase the area covered by bogs and, contrary to general expectations, lead to a retreat rather than an advance in the northern limit of the boreal forest. High water-table levels are not automatically detrimental to forest survival as can be seen in swamp, bottom land and mangrove forests. Consequently, the inhibitory effects of flooding on tree survival and regeneration in northern regions should not be uncritically accepted as merely due to high water levels. Evidence is discussed which suggests that physiological and ecological factors may interact to inhibit forest regeneration in habitats where there is a risk of prolonged winter-flooding combined with warmer winters and cool moist summers.

  3. Corporate Litigation and the Majority Rule: Retreating from the Precipice

    Directory of Open Access Journals (Sweden)

    Aderibigbe , O. I.

    2012-12-01

    Full Text Available Corporate litigation is one of the methods of resolving both internal and external corporate disputes; however Company Laws all over the world establishe a number of different forums for the resolution of internal corporate disputes that occur between directors inter se, shareholders inter se, or between shareholders and directors. However the Majority rule seems to undermine the rights of the minority share holders to seek redress for wrongs committed against the company. Thus the need to protect the minority members of the company and retreat from the precipice of the Majority rule. To enhance the protection of the minority, the Supreme Court's decision in Edokpolo & Company Ltd v. Sem - Edo Wire Industries Ltd1, which added an exception to the list of exceptions to the majority rule stating that the rule in Foss v. Harbottle will not apply when the interest of justice requires it, should be included to the statutory exceptions under CAMA. Consequently, judicial authorities suggest that the law is closing gradually on the rule in Foss v. Harbottle with a demolishing hammer; therefore I would recommend in line with the tide of informed opinion, that sections like section 2992 should be reviewed appropriately to meet the changing faces of law because "the reason of law is the soul of law; ratio legis est anima legis".

  4. Retreatment of silicon slurry by membrane processes

    Energy Technology Data Exchange (ETDEWEB)

    Testa, F. [Universite Paul Cezanne Aix Marseille, Laboratoire de Mecanique, Modelisation et Procedes Propres (M2P2 - UMR-CNRS 6181), Europole de l' Arbois, BP. 80, Batiment Laennec, Hall C, 13545 Aix en Provence Cedex 04 (France); KEMESYS, 125 ZA Verdalai, 13790 Peynier (France); Coetsier, C.; Carretier, E. [Universite Paul Cezanne Aix Marseille, Laboratoire de Mecanique, Modelisation et Procedes Propres (M2P2 - UMR-CNRS 6181), Europole de l' Arbois, BP. 80, Batiment Laennec, Hall C, 13545 Aix en Provence Cedex 04 (France); Ennahali, M.; Laborie, B. [KEMESYS, 125 ZA Verdalai, 13790 Peynier (France); Serafino, C.; Bulgarelli, F. [Rockwood Wafer reclaim France, ZI des Pradeaux, 13850 Greasque (France); Moulin, P., E-mail: philippe.moulin@univ-cezanne.fr [Universite Paul Cezanne Aix Marseille, Laboratoire de Mecanique, Modelisation et Procedes Propres (M2P2 - UMR-CNRS 6181), Europole de l' Arbois, BP. 80, Batiment Laennec, Hall C, 13545 Aix en Provence Cedex 04 (France)

    2011-08-30

    Highlights: {yields} Membrane processes were used to regenerate Silicon CMP slurry effluent {yields} A two-step ultrafiltration process was performed at laboratory and industrial scales {yields} A new hybrid process (membrane ultrafiltration and chemical addition) is developed {yields} A ratio of 0.65 of dissolved chemicals allows RR and TTV to be within specifications {yields} At industrial scale, the hybrid process enables the reuse of electronic effluents. - Abstract: The purpose of the present study is to develop a process to regenerate the polish liquid used in Chemical and Mechanical Polishing (CMP), called 'slurry', and more specifically Silicon CMP slurry. Physico-chemical analyses show a considerable dilution of slurry through washing waters used in polishing. Thus, this effluent has been characterised for a better identification of the deviations from the slurry of reference (Point Of Use). Hence, the principle is to regenerate this effluent by membrane processes. The ultrafiltration results obtained at laboratory scale have led to the development of an industrial prototype. An optimal utilisation of this treatment allows completing a two-step process: the reconcentration by ultrafiltration and a chemical adjustment by addition of concentrated slurry. A stable behaviour of the slurry at the different steps of the process has been observed. Polishing results are similar with retreated and POU slurries. Furthermore, the functioning at industrial scale permits to maintain the performances obtained on the laboratory pilot.

  5. Seaweed communities in retreat from ocean warming.

    Science.gov (United States)

    Wernberg, Thomas; Russell, Bayden D; Thomsen, Mads S; Gurgel, C Frederico D; Bradshaw, Corey J A; Poloczanska, Elvira S; Connell, Sean D

    2011-11-08

    In recent decades, global climate change [1] has caused profound biological changes across the planet [2-6]. However, there is a great disparity in the strength of evidence among different ecosystems and between hemispheres: changes on land have been well documented through long-term studies, but similar direct evidence for impacts of warming is virtually absent from the oceans [3, 7], where only a few studies on individual species of intertidal invertebrates, plankton, and commercially important fish in the North Atlantic and North Pacific exist. This disparity of evidence is precarious for biological conservation because of the critical role of the marine realm in regulating the Earth's environmental and ecological functions, and the associated socioeconomic well-being of humans [8]. We interrogated a database of >20,000 herbarium records of macroalgae collected in Australia since the 1940s and documented changes in communities and geographical distribution limits in both the Indian and Pacific Oceans, consistent with rapid warming over the past five decades [9, 10]. We show that continued warming might drive potentially hundreds of species toward and beyond the edge of the Australian continent where sustained retreat is impossible. The potential for global extinctions is profound considering the many endemic seaweeds and seaweed-dependent marine organisms in temperate Australia.

  6. Calculating lunar retreat rates using tidal rhythmites

    Science.gov (United States)

    Kvale, E.P.; Johnson, H.W.; Sonett, C.P.; Archer, A.W.; Zawistoski, A.N.N.

    1999-01-01

    Tidal rhythmites are small-scale sedimenta??r}- structures that can preserve a hierarchy of astronomically induced tidal periods. They can also preserve a record of periodic nontidal sedimentation. If properly interpreted and understood, tidal rhjthmites can be an important component of paleoastronomy and can be used to extract information on ancient lunar orbital dynamics including changes in Earth-Moon distance through geologic time. Herein we present techniques that can be used to calculate ancient Earth-Moon distances. Each of these techniques, when used on a modern high-tide data set, results in calculated estimates of lunar orbital periods and an EarthMoon distance that fall well within 1 percent of the actual values. Comparisons to results from modern tidal data indicate that ancient tidal rhythmite data as short as 4 months can provide suitable estimates of lunar orbital periods if these tidal records are complete. An understanding of basic tidal theory allows for the evaluation of completeness of the ancient tidal record as derived from an analysis of tidal rhythmites. Utilizing the techniques presented herein, it appears from the rock record that lunar orbital retreat slowed sometime during the midPaleozoic. Copyright ??1999, SEPM (Society for Sedimentary Geology).

  7. Numerical modelling of ground vibration caused by elevated high-speed railway lines considering structure-soil-structure interaction

    DEFF Research Database (Denmark)

    Bucinskas, Paulius; Andersen, Lars Vabbersgaard; Persson, Kent

    2016-01-01

    Construction of high speed railway lines has been an increasing trend in recent years. Countries like Denmark and Sweden plan to expand and upgrade their railways to accommodate high-speed traffic. To benefit from the full potential of the reduced commuting times, these lines must pass through...... densely populated urban areas with the collateral effect of increased noise and vibrations levels. This paper aims to quantify the vibrations levels in the area surrounding an elevated railway line built as a multi-span bridge structure. The proposed model employs finite-element analysis to model...

  8. Simultaneous Determination of Averaged cross Sections for the Formation of Ground and Metastable State when Using Reactor Neutrons as Bombarding Particles the straight line method

    CERN Document Server

    Ribeiro Guevara, S

    2001-01-01

    determine, by this method, the production cross section for the ground state even in those cases where the assumption that one of the states has decayed completely, cannot be warranted.In cases where the ground state half life is much longer than that of the isomeric state, when employing direct methods, it is only possible to determine the sum cross section for the production of both states; therefore, if the metastable production cross section is known, then it is possible to determine, by subtraction, the ground state production cross section.When using the straight-line method, both cross sections can be determined separately.The main limitation of the method is the need to measure the g emission associated to the ground state decay at different time intervals.A parametric analysis of the equations associated to the method shows that under certain conditions it is not possible to apply the method, while under other conditions the method delivers optimum results.The method was applied to the study of four ...

  9. Application of RAMAC Ground Probing Radar in Detection of Tunnel Lining%RAMAC地质雷达在隧道衬砌检测中的应用

    Institute of Scientific and Technical Information of China (English)

    牛连超; 高永涛; 吴顺川

    2011-01-01

    隧道衬砌属隐蔽工程施工.常规检查手段多以钻孔验证为主,带有随机性、有损性,且较盲目.地质雷达是利用高频脉冲电磁波探测地下介质分布的一种地球物理勘探方法.以北京-化稍营高速公路黄羊山隧道初衬检测为例,阐述地质雷达的原理和工作方式,并通过雷达图像的解析,得出钢拱架、初衬等的图像特点,为同类工程的研究提供参考.%Tunnel lining belongs to concealed work construction. Conventional detection measures are mainly-based on drilling for verification, with randomness, prejudice and blindness. Ground probing radar is a method of geophysical exploration to detect the distribution of underground medium using high frequency impulse electromagnetic wave. Taking the detection of Beijtng-Huashaoying Highway Huangyangshan tunnel lining for example, this paper describes the principle and working method of ground probing radar, and obtains the image characteristics of steel arch and initial lining through analysis of radar image, which provides a reference for research of (he similar engineering.

  10. 2D ground motion at a soft viscoelastic layer/hard substratum site in response to SH cylindrical seismic waves radiated by deep and shallow line sources

    CERN Document Server

    Wirgin, A; Wirgin, Armand

    2004-01-01

    We show, essentially by theoretical means, that for a site with the chosen simple geometry and mechanical properties (horizontal, homogeneous, soft viscoelastic layer of infinite lateral extent overlying, and in welded contact with, a homogeneous, hard elastic substratum of half-infinite radial extent, shear-horizontal motion): 1) coupling to Love modes is all the weaker the farther the seismic source (modeled as a line, assumed to lie in the substratum) is from the lower boundary of the soft layer, 2) for a line source close to the lower boundary of the soft layer, the ground response is characterized by possible beating phenomena, and is of significantly-longer duration than for excitation by cylindrical waves radiated by deep sources. Numerical applications of the theory show, for instance, that a line source, located 40m below the lower boundary of a 60m thick soft layer in a hypothetical Mexico City-like site, radiating a SH pulse of 4s duration, produces substantial ground motion during 200s, with marke...

  11. 小电流接地电网故障选线方法的研究%Research on Low Current Grounding Electric Network Fault Line Selection

    Institute of Scientific and Technical Information of China (English)

    何金朋; 聂赫; 刘颖

    2011-01-01

    The 35 kV or below power distribution network in China and small current grounding system single phase occurs single grounding,there is less difference between normal lines and fault line transient zero sequence current,which affects the precision of line selection.In view of this,one kind of digital filter is designed.The pure fault component of zero sequence current is extracted and the data is being analyzed,combined with substation automation generatrix insulate monitoring device and automation reclose device,the fault line is selected.The theoretical analysis and Matlab simulation experiment indicates the accuracy and reliability of line selection method has improved significantly.%针对我国35 kV及以下配电网小电流接地系统发生单相接地时,健全线路与故障线路暂态零序电流相差不大,影响了选线的精度等状况,设计了一种数字滤波器。它可提取零序电流的纯故障分量,对数据进行相关分析,结合变电站自动化母线绝缘监视装置以及自动重合闸装置,选出故障线路。通过理论分析和Matlab实验仿真表明,这种选线方法,其准确性、可靠性有明显提高。

  12. Dissecting the Power Sources of Low-Luminosity Emission-Line Galaxy Nuclei via Comparison of HST-STIS and Ground-Based Spectra

    CERN Document Server

    Constantin, Anca; Ho, Luis C; Barth, Aaron J; Filippenko, Alexei V; Castillo, Christopher A

    2015-01-01

    Using a sample of ~100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of H_alpha and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which Transition Objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at <10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The Transition Objects show a threefold increase in the incidence of broad H_...

  13. 输电线路杆塔接地电阻测量方法%Transmission Line Tower Grounding Resistance Measurement Method

    Institute of Scientific and Technical Information of China (English)

    范大鹏

    2015-01-01

    According to the transmission line tower grounding resistance equipment with the measured transmission lines are there any direct electrical connection,it can be divided into contact measurement and non-contact measurement method,has carried on the detailed introduction of its theory.Combining with the advantages and disadvantages of contact measurement and non-contact measurement method,the initial test contact measurement method may be used for the early stage of the transmission line tower grounding resistance of the layout of satisfy the lightning protection security requirements,such as late for transmission line tower guard,can be used in a non-contact method of measurement,can quickly find problems and in a timely manner.Regular testing of transmission line tower grounding resistance is also important to ensure the safe operation of the transmission line maintenance.%根据输电线路杆塔接地电阻设备与被测输电线路有无直接电气的连接,可将其划分为接触式测量方法和非接触式测量方法,对其原理进行了翔实介绍。结合接触式测量方法和非接触式测量方法的优缺点,初期的测试可以采用接触式测量方法进行前期输电线路杆塔的接地电阻的布置,使其满足防雷等安全要求,后期对输电线路杆塔进行巡防时,可以采用非接触式测量方法,能较快地发现问题并及时进行防护。定期检测输电线路杆塔的接地电阻也是维护输电线路安全运行的重要保证。

  14. Rituximab Retreatment for Low-Tumor Burden Follicular Lymphoma

    Science.gov (United States)

    A summary of results from a randomized clinical trial of patients with low–tumor burden follicular lymphoma that compared maintenance therapy with rituximab versus retreatment with rituximab only when there was evidence of disease progression.

  15. Managed retreat as a response to natural hazard risk

    Science.gov (United States)

    Hino, Miyuki; Field, Christopher B.; Mach, Katharine J.

    2017-03-01

    Managed retreat is a potentially important climate change adaptation option, providing an alternative to structural protection or accommodation measures to manage natural hazard risk. However, its application faces challenges given the projected scale of climate-induced displacement and the difficulties of resettlement. We evaluate the drivers, barriers and outcomes of 27 recent cases of managed retreat that have resettled approximately 1.3 million people. A conceptual model based on two key factors--who benefits from retreat and who initiates it--organizes the diverse set of cases into four quadrants. Different sociopolitical dimensions emerge as particularly influential in each quadrant. The model establishes a foundation for understanding and anticipating case-specific complexities. It can be used to unpack the landscape of managed retreat and evaluate its potential future applications.

  16. Centennial glacier retreat as categorical evidence of regional climate change

    Science.gov (United States)

    Roe, Gerard H.; Baker, Marcia B.; Herla, Florian

    2016-12-01

    The near-global retreat of glaciers over the last century provides some of the most iconic imagery for communicating the reality of anthropogenic climate change to the public. Surprisingly, however, there has not been a quantitative foundation for attributing the retreats to climate change, except in the global aggregate. This gap, between public perception and scientific basis, is due to uncertainties in numerical modelling and the short length of glacier mass-balance records. Here we present a method for assessing individual glacier change based on the signal-to-noise ratio, a robust metric that is insensitive to uncertainties in glacier dynamics. Using only meteorological and glacier observations, and the characteristic decadal response time of glaciers, we demonstrate that observed retreats of individual glaciers represent some of the highest signal-to-noise ratios of climate change yet documented. Therefore, in many places, the centennial-scale retreat of the local glaciers does indeed constitute categorical evidence of climate change.

  17. Monastic retreat and pastoral care in the Dutch Reformed tradition

    Directory of Open Access Journals (Sweden)

    C.H. (Kaaiman Schutte

    2006-10-01

    Full Text Available Of late, there has been a growing interest in retreat among clergy and members of congregations in the Dutch Reformed tradition in South Africa. The article investigates the relevance of the monastic traditions for this growing interest in Reformed circles. It focuses on aspects of retreat such as the role of holy places in the monastic traditions (e.g., monasteries, cathedrals, retreat centers and the experience of silence, solitude, regeneration, divine presence and spiritual formation. Proceeding from an epistemological reflection on the subject as described in a previous article, the aim of this article is to explore the “action of retreat” as a narrative research journey and pilgrimage in order to investigate the relevance of the Benedictine, Franciscan and Taizé monastic-mystic traditions (seen as an associative/mystic spirituality for retreat in the Dutch Reformed tradition (which is seen as a disassociative/rational/ dogmatic spirituality.

  18. Cooperative Spatial Retreat for Resilient Drone Networks †

    Science.gov (United States)

    Kang, Jin-Hyeok; Kwon, Young-Min; Park, Kyung-Joon

    2017-01-01

    Drones are broadening their scope to various applications such as networking, package delivery, agriculture, rescue, and many more. For proper operation of drones, reliable communication should be guaranteed because drones are remotely controlled. When drones experience communication failure due to bad channel condition, interference, or jamming in a certain area, one existing solution is to exploit mobility or so-called spatial retreat to evacuate them from the communication failure area. However, the conventional spatial retreat scheme moves drones in random directions, which results in inefficient movement with significant evacuation time and waste of battery lifetime. In this paper, we propose a novel spatial retreat technique that takes advantage of cooperation between drones for resilient networking, which is called cooperative spatial retreat (CSR). Our performance evaluation shows that the proposed CSR significantly outperforms existing schemes. PMID:28467390

  19. Climate indices, rainfall onset and retreat, and malaria in Nigeri

    Directory of Open Access Journals (Sweden)

    A.J. Thomso

    2010-12-01

    Full Text Available Background & objectives: Rainfall in western sub-Saharan Africa is related to seasonal shifts ofthe Inter-tropical Convergence Zone, which moves northward early in the year, retreating in thesecond half of the year. The objective of the present study was to determine significant relationshipsbetween onset and retreat timing and climate indices. The relationship between timing and malariacase reporting was then evaluated.Methods: Relationships between published rainfall onset and retreat dates for Nigeria from 1971–2000 were evaluated in relation to pairs of climate indices using response surface analysis. Graphicalrepresentation of the response surface in relation to the underlying data was used to identify instancesof overfitting. Association of onset and retreat timing with published case reporting records wasevaluated using graphical and correlation analysis.Results: Onset timing and rate of advance were related to ENSO (El Niño-Southern Oscillation,in combination with the Northern Annular Mode (NAM, while retreat timing was related to NAO(North Atlantic Oscillation, in combination with the East Pacific (EP or West Pacific (WPindex, depending on location. Later onset was associated with faster northward progression ofonset. Retreat date at Kano, the most northerly of the study locations, increased over the period1990–2000, with higher case reporting for Nigeria as a whole being associated with the last threeyears of that period.Interpretation & conclusion: Rainfall retreat occurs much faster than onset, with onset and retreattiming and rate of onset advance being related to combinations of climate indices rather than to asingle index. Threshold for determining a “rainy” day would influence results. The increase innational case reporting with delayed retreat at Kano may be related to the extension of the shorttransmission period in the north.

  20. Population density of tropical forest frogs: relation to retreat sites.

    Science.gov (United States)

    Stewart, M M; Pough, F H

    1983-08-05

    The forest frog Eleutherodactylus coqui defends specific sites for retreats and nests in the Luquillo Forest, Puerto Rico. The hypothesis that shortages of nest and retreat sites limit population size was tested by placing 100 bamboo frog houses in plots measuring 100 square meters in areas of high frog density. These new sites were readily adopted by adult frogs. After one year, experimental plots had significantly more nests and frogs of all sizes than did control plots.

  1. Method Study Based on Ground Line Current Division Achieve Grounding Fault Location of DC Transmission Lines%基于地线分流实现直流输电线路接地故障区段定位的方法

    Institute of Scientific and Technical Information of China (English)

    王法; 曾东; 许金明; 张勇

    2012-01-01

    本文针对直流输电线路地线与杆塔非绝缘连接的特点,分析线路发生不同类型的接地故障时在各杆塔某一根地线上的故障电流分流特征。通过采集输电线路地线上故障电流的方向实现故障定位,从而为故障情况下不同的输电线路运维单位辅助决策服务。%In this article, according to DC transmission lines are non-isolated connected with tower, when different types of ground fault occur,we analyze the characteristics of fault current division through ground line of different towders. By collecting the direction of fault current in the ground line to achieve fault location. As a result, it supports decision service for the units of operation and maintenance of transmission lines when faults accur.

  2. Effect of retreatment on the end-stage sudden deafness.

    Science.gov (United States)

    Suoqiang, Zhai; Ning, Yu; Guiliang, Zheng; Yuhua, Zhu; He, Qin

    2012-03-01

    Microcirculatory disturbance of inner ear is probably one of the important etiological factors of sudden deafness. The purpose of this study was to evaluate the effect of retreatment on the end-stage sudden deafness. For this purpose, the patients who met with the criteria for sudden deafness and showed poor response to conventional therapy over 2 months were assigned randomly to the retreatment group. Pure tone audiometry was conducted before and after retreatment among the 103 patients (112 ears). Sodium bicarbonate and dexamethasone were injected by intravenous drip for 2 days and batroxobin 5BU for 6 days. Data were analyzed using analysis of variance and t test to determine the efficacy of retreatment. These data show that the efficacy rate in retreatment group was 46.43% and the difference between before and after retreatment was significant (P sudden deafness could improve the audition of the patients and should be valuable in clinics. In this regard, the combination of sodium bicarbonate and dexamethasone proved a rational therapeutic regimen for the end-stage sudden deafness. However, further large-size multicenter studies will be required for independent validation of these findings.

  3. Retreatment with Epidermal Growth Factor Receptor Inhibitor After Initial Failure in Advanced Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Tongtong AN

    2011-03-01

    Full Text Available Background and objective The epidermal growth factor receptor tyrosine kinase inhibitor (EGFRTKI shows favorable antitumor activity against chemorefractory non-small cell lung cancer (NSCLC. However, patients with advanced NSCLC have limited treatment options available if they are refractory to EGFR-TKI. To study the influence of the retreatment EGFR-TKI after failure of first-line TKI, we carried out this retrospective study. Methods Total 71 patients were analyzed who experienced treatment failure from their initial use of EGFR-TKI. After a period of time, they were retreated with TKI as tumor progression was observed. Results Of the 71 patients who received retreatment TKI, it was observed in 7% in partial response (PR, 36.6% in stable disease (SD, 56.3% in progressive disease (PD. Disease control rate (DCR was 43.7%. Twenty-six (36.6% patients were well controlled by retreatment with TKI monotherapy for not less than 3 months. Five (7.0% patients had partial response. Exon 21 mutation, PFS not less than 6 months during initial treatment TKI, and the interval not less than 3 months between initial treatment, and retreatment with TKI was associated with a good progression free survival based on univariate COX analysis (P=0.034; P=0.013; P=0.046. Conclusion It has been shown the possibility that retreatment with TKI might be useful when (1 Exon 21 has active mutation, (2 initial treatment shows a favorable PFS (≥ 6 months, and (3 there has been a period of time (≥3 months following the termination of the initial TKI treatment.

  4. Quick ice mass loss and abrupt retreat of the maritime glaciers in the Kangri Karpo Mountains, southeast Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YANG Wei; YAO TanDong; XU BaiQing; WU GuangJian; MA LingLong; XIN XiaoDong

    2008-01-01

    The maritime glaciers are sensitive to climate change because of high annual precipitation and high air temperature in the region.A combined comprehensive study was carried out based on glacier mass balance observation,GPS-based glacier terminus position survey,glacier Ground Penetrating Radar,topography maps and RS satellite images in the Kangri Karpo Mountains,Southeast Tibet.The study revealed a strong ice mass loss and quick glacier retreat since the 1970s.Ata Glacier,one glacier from the south slope of the Kangri Karpo Mountains,has formed a 6-km-long terminal moraine zone at the end of the glacier since the 1970s,and the accelerating retreat is largely due to the strong glacier sur-face melting.Mass balance study on the other four glaciers on the northern side of the Kangri Karpo Mountains shows that they are in large negative mass balance and the glaciers had retreated 15-19 m from May 2006 to May 2007.The in-situ glacier observation also shows that the glacier retreat is more obvious in small glaciers.The enhanced ice mass deficit caused by climate warming and the ongoing extinction of many small glaciers in this region could seriously affect the water resources,environ-ments,local climate and regional sustainable development in the near future.

  5. Numerical modelling of ground vibration caused by elevated high-speed railway lines considering structure-soil-structure interaction

    DEFF Research Database (Denmark)

    Bucinskas, Paulius; Andersen, Lars Vabbersgaard; Persson, Kent

    2016-01-01

    the bridge structure, including a multi-degree-of-freedom vehicle model and accounting for the track unevenness via a nonlinear contact model. The foundations are implemented as rigid footings resting on the ground surface, while the soil is modelled utilizing Green’s function for a horizontally layered half......-space. The paper analyses the effects of structure-soil-structure interaction on the dynamic behaviour of the surrounding soil surface. The effects of different soil stratification and material properties as well as different train speeds are assessed. Finally, the drawbacks of simplifying the numerical model...

  6. Optimal Design of Transmission Lines Pole Tower Grounding Down Lead%输电线路铁塔接地引下线优化设计

    Institute of Scientific and Technical Information of China (English)

    代鑫波; 崔勇; 陈湘华

    2013-01-01

    针对传统接地引下线存在的易腐蚀和材料质地太硬的缺陷,提出将接地引下线的制作材料用镀锌钢绞线代替,同时制定了钢绞线接地引下线的安装方法,并通过热稳定计算确定了钢绞线截面积.实例应用结果表明,该优化设计方法安装简单、方便,成本小,同时在减少输电线路维护工作量、运行成本和延长接地引下线使用寿命等方面均具有很强的实用性.%Traditional grounding down lead has defects of corrosion easily and too hard material texture. This paper presents the grounding wire galvanized steel strand for instead of round steel and designs installation process. And then the steel wire cross-sectional area is determined by thermal stability calculation. Example results show that the optimized design scheme has advantages of simple installation and low cost. At the same time, it has practicability of reducing the transmission line maintenance workload, operation cost and prolonging the service life of grounding down lead.

  7. Knickpoint Retreat: the Role of Channel Self-Organisation

    Science.gov (United States)

    Baynes, E.; Lague, D.; Attal, M.

    2016-12-01

    Landscape connectivity occurs through the valley network, and the action of rivers within these valleys controls both landscape morphology, and landscape response to tectonic or climatic change. Such response to transient forcing is manifested in bedrock river profiles through migrating `knickzones' or `knickpoints', that separate a downstream reach, broadly in equilibrium with the new conditions and an upstream reach which is yet to adjust. Knickpoints therefore mark a dynamic boundary location within mountain landscapes, yet the complexities of the mechanisms of knickpoint retreat are often ignored in studies of landscape evolution. We carried out a series of box flume experiments (65 cm long, 30 cm wide), to explore the importance of mean discharge and substrate strength on the form and migration of knickpoints in a cohesive homogenous substrate. The retreat rate of knickpoints is independent of mean discharge, with knickpoints retreating faster through a weaker substrate. Despite an order of magnitude increase in discharge during our experiments, the bed shear stress remains almost constant due to a self-regulatory response of channel width to higher discharge, leading to no change in the upstream retreat rate of the waterfalls. These experiments challenge the established assumption in models of landscape evolution that a simple relationship exists between knickpoint retreat and discharge/drainage area, and we hypothesise that the correlation between knickpoint retreat and drainage area identified in some landscapes is caused by increasing bedload flux (the `tools' for erosion) with drainage area. Knickpoint retreat modelling approaches should therefore be re-evaluated, and greater attention paid to the role of bedload flux and connectivity between river channels and hillslopes.

  8. Glacier retreat in New Zealand during the Younger Dryas stadial.

    Science.gov (United States)

    Kaplan, Michael R; Schaefer, Joerg M; Denton, George H; Barrell, David J A; Chinn, Trevor J H; Putnam, Aaron E; Andersen, Bjørn G; Finkel, Robert C; Schwartz, Roseanne; Doughty, Alice M

    2010-09-09

    Millennial-scale cold reversals in the high latitudes of both hemispheres interrupted the last transition from full glacial to interglacial climate conditions. The presence of the Younger Dryas stadial (approximately 12.9 to approximately 11.7 kyr ago) is established throughout much of the Northern Hemisphere, but the global timing, nature and extent of the event are not well established. Evidence in mid to low latitudes of the Southern Hemisphere, in particular, has remained perplexing. The debate has in part focused on the behaviour of mountain glaciers in New Zealand, where previous research has found equivocal evidence for the precise timing of increased or reduced ice extent. The interhemispheric behaviour of the climate system during the Younger Dryas thus remains an open question, fundamentally limiting our ability to formulate realistic models of global climate dynamics for this time period. Here we show that New Zealand's glaciers retreated after approximately 13 kyr bp, at the onset of the Younger Dryas, and in general over the subsequent approximately 1.5-kyr period. Our evidence is based on detailed landform mapping, a high-precision (10)Be chronology and reconstruction of former ice extents and snow lines from well-preserved cirque moraines. Our late-glacial glacier chronology matches climatic trends in Antarctica, Southern Ocean behaviour and variations in atmospheric CO(2). The evidence points to a distinct warming of the southern mid-latitude atmosphere during the Younger Dryas and a close coupling between New Zealand's cryosphere and southern high-latitude climate. These findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the North Atlantic led to a strong interhemispheric thermal gradient during late-glacial times, in turn leading to increased upwelling and CO(2) release from the Southern Ocean, thereby triggering Southern Hemisphere warming during the northern Younger Dryas.

  9. ROVIBRATIONAL LINE LISTS FOR NINE ISOTOPOLOGUES OF THE CO MOLECULE IN THE X {sup 1}Σ{sup +} GROUND ELECTRONIC STATE

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang; Gordon, Iouli E.; Rothman, Laurence S. [Harvard-Smithsonian Center for Astrophysics, Atomic and Molecular Physics Division, Cambridge, MA 02138 (United States); Tan, Yan; Hu, Shui-Ming [Hefei National Laboratory for Sciences at Microscale, University of Science and Technology of China, 230026 Hefei (China); Kassi, Samir; Campargue, Alain [Laboratoire Interdisciplinaire de Physique, CNRS UMR 5588, Université Joseph Fourier de Grenoble, B.P. 87, F-38402 Saint-Martin-d' Hères Cedex (France); Medvedev, Emile S., E-mail: igordon@cfa.harvard.edu [The Institute of Problems of Chemical Physics, Russian Academy of Science, Prospect Akademika Semenova 1, 142432 Chernogolovka (Russian Federation)

    2015-01-01

    Extensive rovibrational line lists were computed for nine isotopologues of the CO molecule, namely, {sup 12}C{sup 16}O, {sup 12}C{sup 17}O, {sup 12}C{sup 18}O, {sup 13}C{sup 16}O, {sup 13}C{sup 17}O, {sup 13}C{sup 18}O, {sup 14}C{sup 16}O, {sup 14}C{sup 17}O, and {sup 14}C{sup 18}O in the ground electronic state with v ≤ 41, Δv ≤ 11, and J ≤ 150. The line intensity and position calculations were carried out using a newly determined piece-wise dipole moment function (DMF) in conjunction with the wavefunctions calculated from an experimentally determined potential energy function from Coxon and Hajigeorgiou. A direct-fit method that simultaneously fits all the reliable experimental rovibrational matrix elements has been used to construct the dipole moment function near equilibrium internuclear distance. In order to extend the amount and quality of input experimental parameters, new Cavity Ring Down Spectroscopy experiments were carried out to enable measurements of the lines in the 4-0 band with low uncertainty as well as the first measurements of lines in the 6-0 band. A new high-level ab initio DMF, derived from a finite field approach has been calculated to cover internuclear distances far from equilibrium. Accurate partition sums have been derived for temperatures up to 9000 K. In addition to air- and self-induced broadening and shift parameters, those induced by CO{sub 2} and H{sub 2} are now provided for planetary applications. A complete set of broadening and shift parameters was calculated based on sophisticated extrapolation of high-quality measured data. The line lists, which follow HITRAN formalism, are provided as supplementary material.

  10. Forecasting Stability or Retreat in Emerging Democratic Regimes

    Directory of Open Access Journals (Sweden)

    Snigdha Dewal

    2013-05-01

    Full Text Available Drawing on the literatures on elite transitions, factionalism and the new institutionalism, this paper hypothesizes that the stability of partially democratic and emerging democratic regimes is dependent on the willingness of elites to make credible commitments to cooperate and comply with democratic rules. That willingness (or lack thereof can be signaled by the presence of cooperative or conflict-precipitating events and actions in the periods around elections. We identify and analyze a variety of intra-elite interactions and demonstrate that conflict-precipitating events significantly increase the odds of a democratic retreat in the months before or just after an election, while cooperative events can balance them and prevent retreat. Using event data collected from 40 low- and middle-income countries for two-year periods around national elections between 1991 and 2007 we show that the imbalance of conflict-precipitating over cooperative events is far greater in cases of retreat from democracy. Furthermore, international intervention and pressure had a negative relationship with democratic stability. A logistic regression model accurately identified democratic retreat in 79 percent of the cases examined. Factor analysis revealed several common patterns of intra-elite conflict that can lead to democratic retreat, or conversely, patterns of cooperative events that bolster democratic consolidation. Finally, the data strongly argues for a model of democratic development that depends on open-ended elite maneuvering and the emergence of elite agreements, rather than a model where strong prior institutional constraints determine elite actions.

  11. Forecasting Stability or Retreat in Emerging Democratic Regimes

    Directory of Open Access Journals (Sweden)

    Snigdha Dewal

    2013-05-01

    Full Text Available Drawing on the literatures on elite transitions, factionalism and the new institutionalism, this paper hypothesizes that the stability of partially democratic and emerging democratic regimes is dependent on the willingness of elites to make credible commitments to cooperate and comply with democratic rules. That willingness (or lack thereof can be signaled by the presence of cooperative or conflict-precipitating events and actions in the periods around elections. We identify and analyze a variety of intra-elite interactions and demonstrate that conflict-precipitating events significantly increase the odds of a democratic retreat in the months before or just after an election, while cooperative events can balance them and prevent retreat. Using event data collected from 40 low- and middle-income countries for two-year periods around national elections between 1991 and 2007 we show that the imbalance of conflict-precipitating over cooperative events is far greater in cases of retreat from democracy. Furthermore, international intervention and pressure had a negative relationship with democratic stability. A logistic regression model accurately identified democratic retreat in 79 percent of the cases examined. Factor analysis revealed several common patterns of intra-elite conflict that can lead to democratic retreat, or conversely, patterns of cooperative events that bolster democratic consolidation. Finally, the data strongly argues for a model of democratic development that depends on open-ended elite maneuvering and the emergence of elite agreements, rather than a model where strong prior institutional constraints determine elite actions.

  12. Special requisites for ground switch operation of parallel circuits of strongly connected transmission lines; Requisitos especiais de manobra para chaves de terra de circuitos paralelos de linhas de transmissao fortemente acoplados

    Energy Technology Data Exchange (ETDEWEB)

    Amon Filho, J.; Kastrup Filho, O.; Franca, W.J. [FURNAS, Rio de Janeiro, RJ (Brazil)

    1993-12-31

    This work aims to present results of a qualitative and quantitative analysis of the problem concerning the ground switch turn off operation of transmission lines parallel circuits involving computer simulations and field tests, being such tests compared to standards and constant criteria of the technical specifications of such ground switches. The so far achieved conclusions indicate that the arc resistors installed in the ground switches have been satisfactory solving the problem of the interruption of induced currents by those ground switches. 7 refs., 2 figs., 3 tabs.

  13. Ocean forcing of glacier retreat in the western Antarctic Peninsula.

    Science.gov (United States)

    Cook, A J; Holland, P R; Meredith, M P; Murray, T; Luckman, A; Vaughan, D G

    2016-07-15

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region.

  14. Comparison of the amount of apical debris extrusion associated with different retreatment systems and supplementary file application during retreatment process

    Science.gov (United States)

    Çiçek, Ersan; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can

    2016-01-01

    Background: The type of instrument affects the amount of debris extruded. The aim of this study was to compare the effect of retreatment systems and supplementary file application on the amount of apical debris extrusion. Materials and Methods: Forty-eight extracted mandibular premolars with a single canal and similar length were selected. The root canals were prepared with the ProTaper Universal system with a torque-controlled engine. The root canals were dried and were obturated using Gutta-percha and sealer. The specimens were randomly divided into four equal groups according to the retreatment procedures (Group 1, Mtwo retreatment files; Group 2, Mtwo retreatment files + Mtwo rotary file #30 supplementary file; Group 3, ProTaper Universal retreatment (PTUR) files; and Group 4, PTUR files + ProTaper F3 supplementary file). The extruded debris during instrumentation were collected into preweighed Eppendorf tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. Three consecutive weights were obtained for each tube. Results: No statistically significant difference was found in the amount of apically extruded debris between Groups 1 and 3 (P = 0.590). A significant difference was observed between Groups 1 and 2 (P < 0.05), and between Groups 3 and 4 (P < 0.05). Conclusions: The use of supplementary file significantly increased the amount of apically extruded debris. PMID:27563185

  15. The Timing of Arctic Sea Ice Advance and Retreat as an Indicator of Ice-Dependent Marine Mammal Habitat

    Science.gov (United States)

    Stern, H. L.; Laidre, K. L.

    2013-12-01

    The Arctic is widely recognized as the front line of climate change. Arctic air temperature is rising at twice the global average rate, and the sea-ice cover is shrinking and thinning, with total disappearance of summer sea ice projected to occur in a matter of decades. Arctic marine mammals such as polar bears, seals, walruses, belugas, narwhals, and bowhead whales depend on the sea-ice cover as an integral part of their existence. While the downward trend in sea-ice extent in a given month is an often-used metric for quantifying physical changes in the ice cover, it is not the most relevant measure for characterizing changes in the sea-ice habitat of marine mammals. Species that depend on sea ice are behaviorally tied to the annual retreat of sea ice in the spring and advance in the fall. Changes in the timing of the spring retreat and the fall advance are more relevant to Arctic marine species than changes in the areal sea-ice coverage in a particular month of the year. Many ecologically important regions of the Arctic are essentially ice-covered in winter and ice-free in summer, and will probably remain so for a long time into the future. But the dates of sea-ice retreat in spring and advance in fall are key indicators of climate change for ice-dependent marine mammals. We use daily sea-ice concentration data derived from satellite passive microwave sensors to calculate the dates of sea-ice retreat in spring and advance in fall in 12 regions of the Arctic for each year from 1979 through 2013. The regions include the peripheral seas around the Arctic Ocean (Beaufort, Chukchi, East Siberian, Laptev, Kara, Barents), the Canadian Arctic Archipelago, and the marginal seas (Okhotsk, Bering, East Greenland, Baffin Bay, Hudson Bay). We find that in 11 of the 12 regions (all except the Bering Sea), sea ice is retreating earlier in spring and advancing later in fall. Rates of spring retreat range from -5 to -8 days/decade, and rates of fall advance range from +5 to +9

  16. Retreat history of the last glacial maximum ice sheet in Ross Sea, Antarctica

    Science.gov (United States)

    Shipp, Stephanie Staples

    High-resolution geophysical and geologic data were acquired in western and central Ross Sea, Antarctica, to determine the: (1) maximum extent and configuration of the ice sheet during the Last Glacial Maximum (LGM); (2) conditions and processes at the base of the expanded ice sheet and their role in ice stream activity; and (3) relative retreat history of the ice sheet. This information can provide geologic constraints for modeling of ice-sheet retreat. The research formed the basis for development of a public Web site (http://www.glacier.rice.edu) and for middle-school earth-science instructional materials. Based on identification of isolated grounding-zone wedges and consistency of mega-scale glacial lineations, the LGM ice edge reached the Coulman Island region in western Ross Sea. The maximum extent in central Ross Sea occurred at the continental-shelf edge, based on the presence of mega-scale glacial lineations, glacio-tectonic features, and shelf-edge gullies. Streaming ice, overlying a deforming bed typically catastrophic collapse of the ice sheet.

  17. Promoting Writing for Research: The "Writing Retreat" Model

    Science.gov (United States)

    Singh, R. J.

    2012-01-01

    Research papers take a long time to write and in an academic environment where the "publish or perish" clause applies, writing retreats are a way of creating time and space to write academic articles in a concentrated period of time. This article examines ways in which academics can write more articles for publication. In particular it…

  18. Exploring the Effectiveness of a Retreat Method for Extension Staff

    Science.gov (United States)

    Worker, Steven M.; Hill, Russell D.; Miller, JoLynn C.; Go, Charles G.; Boyes, Rita J.

    2015-01-01

    The California 4-H Association hosted two retreats to support its members with goals of balancing professional development with intentional relationship building. Evaluations demonstrated that staff found the intentional balance of time spent in unstructured, semi-structured, and structured time offered opportunities to grow professionally while…

  19. Scientists Discover New Possibilities at Scientific Investigators Retreat | Poster

    Science.gov (United States)

    By Nancy Parrish, Staff Writer; photos by Richard Frederickson, Staff Photographer Scientists who attended the 2015 NCI Intramural Scientific Investigators Retreat on Jan. 13 had a chance to discuss research results with other investigators from across the National Cancer Institute. And this year, they could also explore new possibilities for the future of their research.

  20. Incidence of apical crack initiation and propagation during the removal of root canal filling material with ProTaper and Mtwo rotary nickel-titanium retreatment instruments and hand files.

    Science.gov (United States)

    Topçuoğlu, Hüseyin Sinan; Düzgün, Salih; Kesim, Bertan; Tuncay, Oznur

    2014-07-01

    The aim of this study was to determine the incidence of crack initiation and propagation in apical root dentin after retreatment procedures performed by using 2 rotary retreatment systems and hand files with additional instrumentation. Eighty extracted mandibular premolars with single canals were selected. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the control group, and no preparation was performed. The remaining 60 teeth were prepared to size 35 with rotary files and filled with gutta-percha and AH Plus sealer. Specimens were then divided into 3 groups (n = 20), and retreatment procedures were performed with the following devices and techniques: ProTaper Universal retreatment files, Mtwo retreatment files, and hand files. After retreatment, the additional instrumentation was performed by using size 40 ProTaper, Mtwo, and hand files. Digital images of the apical root surface were recorded before preparation, after instrumentation, after filling, after retreatment, and after additional instrumentation. The images were then inspected for the presence of any new apical cracks and propagation. Data were analyzed with the logistic regression and Fisher exact tests. All experimental groups caused crack initiation and propagation after use of retreatment instruments. The ProTaper and Mtwo retreatment groups caused greater crack initiation and propagation than the hand instrument group (P propagation, whereas hand files caused neither crack initiation nor propagation (P propagation in apical dentin. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  1. Outcomes of nonsurgical retreatment and endodontic surgery: a systematic review.

    Science.gov (United States)

    Torabinejad, Mahmoud; Corr, Robert; Handysides, Robert; Shabahang, Shahrokh

    2009-07-01

    The purpose of this systematic review was to compare the clinical and radiographic outcomes of nonsurgical retreatment with those of endodontic surgery to determine which modality offers more favorable outcomes. The study began with targeted electronic searches of MEDLINE, PubMed, and Cochrane databases, followed with exhaustive hand searching and citation mining for all articles reporting clinical and/or radiographic outcomes for at least a mean follow-up of 2 years for these procedures. Pooled and weighted success rates were determined from a meta-analysis of the data abstracted from the articles. A significantly higher success rate was found for endodontic surgery at 2-4 years (77.8%) compared with nonsurgical retreatment for the same follow-up period (70.9%; P < .05). At 4-6 years, however, this relationship was reversed, with nonsurgical retreatment showing a higher success rate of 83.0% compared with 71.8% for endodontic surgery (P < .05). Insufficient numbers of articles were available to make comparisons after 6 years of follow-up period. Endodontic surgery studies showed a statistically significant decrease in success with each increasing follow-up interval (P < .05). The weighted success for 2-4 years was 77.8%, which declined at 4-6 years to 71.8% and further declined at 6+ years to 62.9% (P < .05). Conversely, the nonsurgical retreatment success rates demonstrated a statistically significant increase in weighted success from 2-4 years (70.9%) to 4-6 years (83.0%; P < .05). On the basis of these results it appears that endodontic surgery offers more favorable initial success, but nonsurgical retreatment offers a more favorable long-term outcome.

  2. Large ensemble modeling of the last deglacial retreat of the West Antarctic Ice Sheet: comparison of simple and advanced statistical techniques

    Science.gov (United States)

    Pollard, David; Chang, Won; Haran, Murali; Applegate, Patrick; DeConto, Robert

    2016-05-01

    A 3-D hybrid ice-sheet model is applied to the last deglacial retreat of the West Antarctic Ice Sheet over the last ˜ 20 000 yr. A large ensemble of 625 model runs is used to calibrate the model to modern and geologic data, including reconstructed grounding lines, relative sea-level records, elevation-age data and uplift rates, with an aggregate score computed for each run that measures overall model-data misfit. Two types of statistical methods are used to analyze the large-ensemble results: simple averaging weighted by the aggregate score, and more advanced Bayesian techniques involving Gaussian process-based emulation and calibration, and Markov chain Monte Carlo. The analyses provide sea-level-rise envelopes with well-defined parametric uncertainty bounds, but the simple averaging method only provides robust results with full-factorial parameter sampling in the large ensemble. Results for best-fit parameter ranges and envelopes of equivalent sea-level rise with the simple averaging method agree well with the more advanced techniques. Best-fit parameter ranges confirm earlier values expected from prior model tuning, including large basal sliding coefficients on modern ocean beds.

  3. Self-healing of single-phase grounding fault for power distribution lines%配电线路单相接地故障自愈方案

    Institute of Scientific and Technical Information of China (English)

    施慎行; 董新洲; 吴家华; 沈冬

    2012-01-01

    A self-healing scheme is presented for the single-phase grounding fault of distribution lines,which consists of four parts:fault detection, faulty feeder selection, faulty section identification and faulty feeder isolation. The fault detection is based on the open-delta-side voltages of PT. A single-phase grounding fault is identified when the measured voltage is greater than the setting value. The faulty feeder selection is based on the current traveling waves. The feeder with different traveling wave polarity is selected as the faulty one. The faulty section identification is based on the synthesized results of faulty feeder selection. After the faulty feeder is selected,close the interconnection switch at the load side first,then open its incoming switch and isolate the power source side of faulty. Simulative results show that the scheme realizes the automatic quick isolation of single-phase grounding fault without power loss of load.%针对配电线路的单相接地故障,提出了故障自愈方案.方案包括单相接地故障检测、故障选线、故障区段识别和接地线路隔离4个部分.故障检测基于母线上的电压互感器开口三角侧电压,当测量电压大于整定值时,判断系统中发生了单相接地故障;故障选线基于线路上的电流行波,极性与众不同的电流行波所在线路为接地线路;故障区段识别基于故障选线的综合结果;选出故障母线后,先闭合接地线路负荷侧的联络开关,再打开接地线路负荷侧进线开关,最后隔离接地线路电源侧.仿真结果表明,所提自愈方案可实现单相接地故障自动快速隔离,故障隔离过程中负荷不失电.

  4. Holocene warming in western continental Eurasia driven by glacial retreat and greenhouse forcing

    Science.gov (United States)

    Baker, Jonathan L.; Lachniet, Matthew S.; Chervyatsova, Olga; Asmerom, Yemane; Polyak, Victor J.

    2017-06-01

    The global temperature evolution during the Holocene is poorly known. Whereas proxy data suggest that warm conditions prevailed in the Early to mid-Holocene with subsequent cooling, model reconstructions show long-term warming associated with ice-sheet retreat and rising greenhouse gas concentrations. One reason for this contradiction could be the under-representation of indicators for winter climate in current global proxy reconstructions. Here we present records of carbon and oxygen isotopes from two U-Th-dated stalagmites from Kinderlinskaya Cave in the southern Ural Mountains that document warming during the winter season from 11,700 years ago to the present. Our data are in line with the global Holocene temperature evolution reconstructed from transient model simulations. We interpret Eurasian winter warming during the Holocene as a response to the retreat of Northern Hemisphere ice sheets until about 7,000 years ago, and to rising atmospheric greenhouse gas concentrations and winter insolation thereafter. We attribute negative δ18O anomalies 11,000 and 8,200 years ago to enhanced meltwater forcing of North Atlantic Ocean circulation, and a rapid decline of δ13C during the Early Holocene with stabilization after about 10,000 years ago to afforestation at our study site. We conclude that winter climate dynamics dominated Holocene temperature evolution in the continental interior of Eurasia, in contrast to regions more proximal to the ocean.

  5. Rate and style of ice stream retreat constrained by new surface-exposure ages: The Minch, NW Scotland

    Science.gov (United States)

    Bradwell, Tom; Small, David; Fabel, Derek; Dove, Dayton; Cofaigh, Colm O.; Clark, Chris; Consortium, Britice-Chrono

    2016-04-01

    Chronologically constrained studies of former ice-sheet extents and dynamics are important for understanding past cryospheric responses and modelling future ice-sheet and sea-level change. As part of the BRITICE-CHRONO project, we present new geomorphological and chronological data from a marine-terminating ice stream system in NW Europe that operated during the Late Weichselian Glaciation. A suite of 51 cosmogenic-nuclide exposure ages from ice sheet moraines and glacially transported boulders constrain the maximum extent of the ice sheet on the continental shelf (~28 ka BP) and its subsequent retreat, between ~27 and 16 ka BP, into a large marine embayment (ca. 7000 km2; the Minch, NW Scotland). Recently acquired swath bathymetry and acoustic sub-bottom profiler data reveal several large transverse grounding-zone wedges up to 40 m thick and 5 km wide with diagnostic acoustic-facies architecture. These seabed sediment wedges mark former quasi-stable positions of grounded marine-terminating ice-stream fronts; their size and thickness suggest long-lived stillstands of the order of centuries. Statistically significant clusters of exposure ages from glacial deposits on islands and intervening headlands shed important new light on the age of these marine grounding-zone wedges and, by inference, the rate and timing of Minch palaeo-ice stream retreat. We find strong evidence for episodic ice stream retreat on the continental shelf between ~28-24 ka BP, in the outer Minch between ~24-22 ka BP, and in the central Minch between 22-18.5 ka BP. In contrast, final ice stream deglaciation (probably rapid and uninterrupted - with the ice sheet margin at or close to the present-day coastline in NW Scotland by 16.1 ka BP. It is hoped that these results will form the empirical basis for future ice-sheet modelling of this dynamically sensitive sector of the British-Irish Ice Sheet.

  6. Investigating Tidewater Glacier Advance/Retreat Cycles Using a Multi-year Dataset Hubbard Glacier, Southeast Alaska

    Science.gov (United States)

    Gadomski, P.; Finnegan, D. C.; Lawson, D. E.; Hanlon, G.

    2009-12-01

    Quantitative high-resolution, multi-year datasets on tidewater glacier terminus activity are difficult and expensive to obtain and few in number. Furthermore, numerous factors influence terminus dynamics, thus requiring a holistic approach to data gathering to understand such activity. This paper describes ongoing research at Hubbard Glacier in Southeast Alaska and how these efforts are improving our understanding of an actively advancing tidewater margin. Hubbard Glacier, the largest tidewater glacier in North America, flows ~125 km from Mt Logan (5959 m) in the St. Elias Mountains to sea level where its terminus continues to thicken, widen and advance at an average rate of 32m/yr. Continued advance of the Hubbard Glacier may dam the channel linking Russell Fiord with Disenchantment Bay and potentially result in flooding of the Situk River destroying a fishery that provides the economic base for the community of Yakutat. As part of a multi-year investigation to monitor and assess the risk of dam formation by Hubbard Glacier, near real-time meteorological and terminus motion data are being monitored, while detailed field and remote sensing investigations quantify glacier activity. These investigations have included bathymetric mapping and hydrographic surveys, aerial and ground-based LiDAR topographic surveys, time-lapse photography and recurring satellite imagery of the glacier since 2005. Over the approximate three years of continuous near-realtime field-based monitoring the duration, patterns and daily rates of terminus advance and retreat are proving to be similar from year to year. These patterns suggest that the onset of advance and retreat may be linked to climate and extreme variations in the tidal cycle are influential in slowing terminus advance and causing periods of retreat to be superimposed onto longer durations of advance. These results when linked to time-lapse photography provide insight into ice marginal mechanisms of calving, while the results of

  7. 500 kV 直流地线融冰方法%Research on the Implementation of DC Ground Wire Ice-melting for 500 kV Niu-Cong Transmission Line

    Institute of Scientific and Technical Information of China (English)

    张锐; 曹双全

    2014-01-01

    介绍输电线路抗冰改造、加装融冰装置及增加覆冰在线监测装置等措施,在线路覆冰初期,启动融冰装置对覆冰导线、地线进行融冰,有效地保护了输电线路的安全。%took many measures such as transmission lines resisting ice, increasing melting ice device and measure of the icing on-line monitoring device, At the beginning of transmission lines iced, starting melting ice device to melt ice for iced conductor lines and grounding lines, taking these measures can protect the safety of the transmission lines effectively.

  8. Research on the Implementation of DC Ground Wire Ice-melting for 500 kV Niu-Cong Transmission Line%500kV直流地线融冰方法

    Institute of Scientific and Technical Information of China (English)

    张锐; 曹双全

    2014-01-01

    介绍输电线路抗冰改造、加装融冰装置及增加覆冰在线监测装置等措施,在线路覆冰初期,启动融冰装置对覆冰导线、地线进行融冰,有效地保护了输电线路的安全。%took many measures such as transmission lines resisting ice, increasing melting ice device and measure of the icing on-line monitoring device, At the beginning of transmission lines iced, starting melting ice device to melt ice for iced conductor lines and grounding lines, taking these measures can protect the safety of the transmission lines effectively.

  9. Sloped Ground Lines - USACE IENC

    Data.gov (United States)

    Department of Homeland Security — These inland electronic Navigational charts (IENCs) were developed from available data used in maintenance of Navigation channels. Users of these IENCs should be...

  10. Technical note: Sensitivity of instrumental line shape monitoring for the ground-based high-resolution FTIR spectrometer with respect to different optical attenuators

    Science.gov (United States)

    Sun, Youwen; Palm, Mathias; Weinzierl, Christine; Petri, Christof; Notholt, Justus; Wang, Yuting; Liu, Cheng

    2017-03-01

    The TCCON (Total Carbon Column Observing Network) and most NDACC (Network for Detection of Atmospheric Composition Change) sites assume an ideal ILS (instrumental line shape) for analysis of the spectra. In order to adapt the radiant energy received by the detector, an attenuator or different sizes of field stop can be inserted in the light path. These processes may alter the alignment of a high-resolution FTIR (Fourier transform infrared) spectrometer, and may result in bias due to ILS drift. In this paper, we first investigated the sensitivity of the ILS monitoring with respect to application of different kinds of attenuators for ground-based high-resolution FTIR spectrometers within the TCCON and NDACC networks. Both lamp and sun cell measurements were conducted after the insertion of five different attenuators in front of and behind the interferometer. The ILS characteristics derived from lamp and sun spectra are in good agreement. ILSs deduced from all lamp cell measurements were compared. As a result, the disturbances to the ILS of a high-resolution FTIR spectrometer with respect to the insertion of different attenuators at different positions were quantified. A potential strategy to adapt the incident intensity of a detector was finally deduced.

  11. Pathological organizations and psychic retreats in eating disorders.

    Science.gov (United States)

    Kadish, Yael Adira

    2012-04-01

    A set of characteristic symptoms allow for the relatively straightforward diagnosis of eating disorders. Simultaneously and paradoxically, underlying the eating disorders are a wide variety of personality organizations/disorders, stretching from the neurotic to the borderline and narcissistic, and even to conditions approaching psychosis. This paper will argue that the inherent commonalities can be ascribed to pathological organizations of a similar nature and quality, operational across the spectrum of eating disorders and functioning in a particular, sadomasochistic way. The typical forms that eating disorders take are based on the specific ways that food and the body are used, that is, symptom manifestation. These distinctive symptom manifestations appear to be related to Steiner's (1982, 1993) notion of a psychic retreat. Pathological organizations and psychic retreats are latent until called upon either sporadically or continuously. When activated, these defensive structures operate like a complex psychic skeleton around which the unique psychodynamics of each patient become rearranged and thereby transformed.

  12. Improved instrumental line shape monitoring for the ground-based, high-resolution FTIR spectrometers of the Network for the Detection of Atmospheric Composition Change

    Directory of Open Access Journals (Sweden)

    F. Hase

    2012-03-01

    Full Text Available We propose an improved monitoring scheme for the instrumental line shape (ILS of high-resolution, ground-based FTIR (Fourier Transform InfraRed spectrometers used for chemical monitoring of the atmosphere by the Network for Detection of Atmospheric Composition Change (NDACC. Good ILS knowledge is required for the analysis of the recorded mid-infrared spectra. The new method applies a sequence of measurements using different gas cells instead of a single calibration cell. Three cells are used: cell C1 is a refillable cell offering 200 mm path length and equipped with a pressure gauge (filled with 100 Pa N2O, cells C2 and C3 are sealed cells offering 75 mm path length. C2 is filled with 5 Pa of pure N2O. Cell C3 is filled with 16 Pa N2O in 200 hPa technical air, so provides pressure-broadened N2O lines. We demonstrate that an ILS retrieval using C1 improves significantly the sensitivity of the ILS retrieval over the current calibration cells used in the network, because this cell provides narrow fully saturated N2O lines. The N2O columns derived from C2 and C3 allow the performance of a highly valuable closure experiment: adopting the ILS retrieved from C1, the N2O columns of C2 and C3 are derived. Because N2O is an inert gas, both columns should be constant on long timescales. Apparent changes in the columns would immediately attract attention and indicate either inconsistent ILS results or instrumental problems of other origin. Two different cells are applied for the closure experiment, because the NDACC spectrometers observe both stratospheric and tropospheric gases: C2 mimics signatures of stratospheric gases, whereas C3 mimics signatures of tropospheric gases.

  13. Aircraft Ground Operation, Servicing, Fluid Lines and Fittings, Mechanics Privileges and Limitations, and Maintenance Publications, Forms and Records (Course Outline), Aviation Mechanics 1 (Power and Frame): 9073.02.

    Science.gov (United States)

    Dade County Public Schools, Miami, FL.

    The course outline consists of five instructional blocks of several units each: (1) Aircraft Ground Operation and Servicing; (2) Fluid Lines and Fittings; (3) Mechanics Requirements, Privileges and Limitations; (4) Maintenance Publications; and, (5) Maintenance forms and Records. It is a basic course of knowledge and skills necessary to any…

  14. Scientific Investigators Retreat Brings Like Minds Together | Poster

    Science.gov (United States)

    Scientists throughout NCI gathered at the 2016 Intramural Scientific Investigators Retreat on Jan. 12, at the Ronald Reagan Building and International Trade Center, to discuss the results of their research with fellow investigators. Several researchers who have made significant advances toward the goal of eliminating the threat of cancer spoke to a packed auditorium of like-minded experts. Speaker topics included the role genetics play in the risk of breast cancer, using fiberglass to...

  15. Glacial Delineation and Ice Retreat on Pico de Orizaba, Mexico

    Science.gov (United States)

    Colby, A. E.; Weissling, B.; Xie, H.

    2011-12-01

    Pico de Orizaba, a dormant stratovolcano at the eastern end of the Trans-Mexican Volcanic Belt at approximately 19 degrees of latitude and the third largest peak in North America (5636 m), hosts what is likely the last significant tropical zone glacier (Jamapa Glacier) in the Northern Hemisphere. Not since the International Geophysical Year of 1957-58 has Pico's glacial environment been studied with any focused effort, perhaps due to the general innaccessibility, high altitude, and steep slopes. As are most glaciers around the world, the Jamapa Glacier is retreating, with a remarkable loss of ice in the past 2 decades. The rate and pattern of retreat is important to understanding climate change forcing as well as understanding environmental and water supply impacts to a substantial human population who live along the base of the volcano. Through the use of satellite imagery (LandSat, ASTER, IKONOS), legacy hand-drawn maps, aerial photographs, and first-hand accounts from climber's expeditions, a reasonably accurate map of almost 60 years of glacial retreat has been produced. Legacy hand-drawn maps of the ice edge, that pre-date the satellite era, did not fit perfectly with modern images when layered in ArcGIS. Oblique perspectives in Google Earth and various aerial and surface-based photographs of the mountain were used to help fit the ice edge to the actual topography. The disparity of satellite image pixel resolution (from 1 m IKONOS to 60 m LandSat) was addressed using various imagery analysis tools (eg. edge detection convolution filters and pixel unmixing) in order to delineate an approximate ice edge for the respective image date. The final map shows the nature of ice edge retreat on Pico de Orizaba from 1945 up until the present (Feb 2011).

  16. Retreatment Predictions in Odontology by means of CBR Systems.

    Science.gov (United States)

    Campo, Livia; Aliaga, Ignacio J; De Paz, Juan F; García, Alvaro Enrique; Bajo, Javier; Villarubia, Gabriel; Corchado, Juan M

    2016-01-01

    The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising.

  17. Retreatment Predictions in Odontology by means of CBR Systems

    Directory of Open Access Journals (Sweden)

    Livia Campo

    2016-01-01

    Full Text Available The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising.

  18. Research on Special Maintenance Tool of Straight Line Tower Ground and OPGW Cable in Overhead Transmission Line%线路直线塔地线及光缆金具维护

    Institute of Scientific and Technical Information of China (English)

    杨军

    2014-01-01

    本文在对架空输电线路直线塔地线支架和地线、 OPGW光缆金具组装方式及杆塔荷载的分析计算基础上,结合机械设计基础理论,确定了初步的专用工具研制方案。通过自行购买材料、零部件,在加工、装配和试用过程中不断完善后,成功研制出一套地线、 OPGW光缆金具维护的专用工具。该专用工具通过在不同电压等级线路、荷载情况下的4次现场试用,完全满足对35 kV~500 kV线路通用通用直线塔地线、 OPGW光缆金具的维护工作,而且与传统的作业方法相比明显提高了作业安全性和工作效率。%Based on the basis of the calculation,combining with the basic mechanical design theory, and analysis of straight wire bracket and a ground wire,OPGW cable for overhead power transmission line and tower load, the special maintenance tool is pre-liminary designed. Through the purchase of materials, parts, continuous improvement in processing, assembly and trial process,successfully developed a set of wire,OPGW cable maintenance special tool. The special tool is through the field test for 4 times in different voltage grade line,load conditions,to meet the needs of 35 kV-500 kV line general linear tower wire,OPGW cable main-tenance work,and compared with the traditional operating method significantly improves the operation safety and efficiency.

  19. Evaluation of Dentin Defect Formation during Retreatment with Hand and Rotary Instruments: A Micro-CT Study

    Directory of Open Access Journals (Sweden)

    Ayca Yilmaz

    2017-01-01

    Full Text Available The purpose of this study was to compare the incidence and longitudinal propagation of dentin defects after gutta-percha removal with hand and rotary instruments using microcomputed tomography. Twenty mandibular incisors were prepared using the balanced-force technique and scanned in a 19.9 μm resolution. Following filling with the lateral compaction technique, gutta-percha was removed with ProTaper Universal Retreatment (PTUR or hand instruments. After rescanning, a total of 24,120 cross-sectional images were analyzed. The numbers, types, and longitudinal length changes of defects were recorded. Defects were observed in 36.90% of the cross sections. A total of 73 defects were comprised of 87.67% craze lines, 2.73% partial cracks, and 9.58% fractures. No significant difference in terms of new defect formation was detected between the retreatment groups. The apical and middle portions of the roots had more dentin defects than the coronal portions. Defects in three roots of the PTUR instrument group increased in length. Under the conditions of this in vitro study, gutta-percha removal seemed to not increase the incidence of dentin defect formation, but the longitudinal defect propagation finding suggests possible cumulative dentinal damage due to additional endodontic procedures. Hand and rotary instrumentation techniques caused similar dentin defect formation during root canal retreatment.

  20. Retreatment with direct-acting antivirals of genotypes 1-3-4 hepatitis C patients who failed an anti-NS5A regimen in real world.

    Science.gov (United States)

    Halfon, Philippe; Scholtès, Caroline; Izopet, Jacques; Larrat, Sylvie; Trimoulet, Pascale; Zoulim, Fabien; Alric, Laurent; Métivier, Sophie; Leroy, Vincent; Ouzan, Denis; de Lédinghen, Victor; Mohamed, Sofiane; Pénaranda, Guillaume; Khiri, Hacène; Thélu, Marie-Ange; Plauzolles, Anne; Chiche, Laurent; Bourlière, Marc; Abravanel, Florence

    2017-10-04

    The aim was to study retreatment according to baseline nonstructural protein 5A (NS5A) resistance-associated substitutions (RASs) after the failure of first-line DAA-based treatment. From January 2014 to March 2016, 2995 HCV-infected patients were treated with NS5A inhibitors in six French liver referral centers; 80 (2.7%) patients relapsed. This "real-world" study included 24 of those 80 patients who had failed to achieve sustained virological response (SVR) on previous NS5A-based therapy. These 24 patients were re-treated with different regimen combinations. Antiviral efficacy was evaluated using the primary endpoints of SVR at weeks 4 and 12 post-treatment (SVR4, SVR12). The presence of NS5A RASs/polymorphisms was found in 20 (80%) patients at baseline of retreatment. All patients achieved SVR with HCV RNA below the lower limit of quantification (<15 IU/mL) by the end of treatment. SVR4 and SVR12 were achieved in 23/24 patients (96%), and the remaining patient relapsed four weeks post-treatment. Based on these results, retreatment of patients after the failure of a first-line NS5A regimen is effective (96% SVR). In the future, either dual or triple therapy regimens may have similar results with shorter treatment duration. Copyright © 2017. Published by Elsevier B.V.

  1. Line parameter study of ozone at 5 and 10 μm using atmospheric FTIR spectra from the ground: A spectroscopic database and wavelength region comparison

    Science.gov (United States)

    Janssen, Christof; Boursier, Corinne; Jeseck, Pascal; Té, Yao

    2016-08-01

    Atmospheric ozone concentration measurements mostly depend on spectroscopic methods that cover different spectral regions. Despite long years of measurement efforts, the uncertainty goal of 1% in absolute line intensities has not yet been reached. Multispectral inter-comparisons using both laboratory and atmospheric studies reveal that important discrepancies exist when ozone columns are retrieved from different spectral regions. Here, we use ground based FTIR to study the sensitivity of ozone columns on different spectroscopic parameters as a function of individual bands for identifying necessary improvements of the spectroscopic databases. In particular, we examine the degree of consistency that can be reached in ozone retrievals using spectral windows in the 5 and 10 μm bands of ozone. Based on the atmospheric spectra, a detailed database inter-comparison between HITRAN (version 2012), GEISA (version 2011) and S&MPO (as retrieved from the website at the end of 2015) is made. Data from the 10 μm window are consistent to better than 1%, but there are larger differences when the windows at 5 μm are included. The 5 μm results agree with the results from 10 μm within ±2% for all databases. Recent S&MPO data are even more consistent with the desired level of 1%, but spectroscopic data from HITRAN give about 4% higher ozone columns than those from GEISA. If four sub-windows in the 5 μm band are checked for consistency, retrievals using GEISA or S&MPO parameters show less dispersion than those using HITRAN, where one window in the P-branch of the ν1 + ν3 band gives about 2% lower results than the other three. The atmospheric observations are corroborated by a direct comparison of the spectroscopic databases, using a simple statistical analysis based on intensity weighted spectroscopic parameters. The bias introduced by the weighted average approach is investigated and it is negligible if relative differences between databases do not correlate with line

  2. The hydro- and multi-isotope geochemistry of iron-rich ground waters emerging at the southern Baltic Sea coast line

    Science.gov (United States)

    Lipka, Marko; Wu, Zijun; Escher, Peter; Struck, Ulrich; Dellwig, Olaf; Schafmeister, Maria; Böttcher*, Michael E.

    2013-04-01

    Iron-rich groundwater springs emerging at the shore zone of the southern Baltic Sea (BS; Site Meschendorf) were examined on a seasonal base for a period of about two years. Besides major, minor, and trace elements, stable isotopes of water (H-2, O-18), dissolved inorganic carbon (DIC; C-13), and sulfate (S-34) were analyzed. The stream bed sediment was extracted for the geochemistry of the newly formed precipitates and further characterized via SEM-EDAX. Subsequently, the hydrogeochemical results were subjected to a thermodynamic analysis via the PHREEQC speciation model. The springs emerge from small pits (about 60 cm diameter; up to 15cm depth). Surrounding sediments are sandy with gravels found at depth and corresponding high permeabilities. The positions of different springs on the shore zone were stable during the investigation period while the shape of the pits and the stream beds may vary due to wind- and wave-driven forces. Selected measurements of spring yield discharges close to 10 L/min. The H-2 and O-18 contents of the spring waters indicate the ground water to originate from relatively young mixed meteoric waters. The hydrochemistry of the springs was similar and showed some variability in between which indicates that the genetic processes for the ground water before reaching the surface may slightly differ. The springs are characterized by dissolved Ca, Mg, Na, DIC and sulfate, mainly reflecting the interaction with soils and bedrocks in the recharge area that is dominated by marly till. The oxygen-free ground water is rich in Fe, P, and DIC. Iron and dissolved sulfate originate from the oxidation of pyrite, as further confirmed by the 34-S signature of sulfate. The carbon isotope signature of DIC indicates a mixture of biogenic CO2 from the soil zone with some water-rock interaction with carbonate minerals. The streams flow towards the BS and, in contact with the atmosphere, outgas carbon dioxide and takes up oxygen. Upon CO2-degassing, C-12 is

  3. The regulation of troponins I, C and ANP by GATA4 and Nkx2-5 in heart of hibernating thirteen-lined ground squirrels, Ictidomys tridecemlineatus.

    Directory of Open Access Journals (Sweden)

    Bryan E Luu

    Full Text Available Hibernation is an adaptive strategy used by various mammals to survive the winter under situations of low ambient temperatures and limited or no food availability. The heart of hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus has the remarkable ability to descend to low, near 0°C temperatures without falling into cardiac arrest. We hypothesized that the transcription factors GATA4 and Nkx2-5 may play a role in cardioprotection by facilitating the expression of key downstream targets such as troponin I, troponin C, and ANP (atrial natriuretic peptide. This study measured relative changes in transcript levels, protein levels, protein post-translational modifications, and transcription factor binding over six stages: euthermic control (EC, entrance into torpor (EN, early torpor (ET, late torpor (LT, early arousal (EA, and interbout arousal (IA. We found differential regulation of GATA4 whereby transcript/protein expression, post-translational modification (phosphorylation of serine 261, and DNA binding were enhanced during the transitory phases (entrance and arousal of hibernation. Activation of GATA4 was paired with increases in cardiac troponin I, troponin C and ANP protein levels during entrance, while increases in p-GATA4 DNA binding during early arousal was paired with decreases in troponin I and no changes in troponin C and ANP protein levels. Unlike its binding partner, the relative mRNA/protein expression and DNA binding of Nkx2-5 did not change during hibernation. This suggests that either Nkx2-5 does not play a substantial role or other regulatory mechanisms not presently studied (e.g. posttranslational modifications are important during hibernation. The data suggest a significant role for GATA4-mediated gene transcription in the differential regulation of genes which aid cardiac-specific challenges associated with torpor-arousal.

  4. Hibernation alters the diversity and composition of mucosa-associated bacteria while enhancing antimicrobial defence in the gut of 13-lined ground squirrels.

    Science.gov (United States)

    Dill-McFarland, Kimberly A; Neil, Katie L; Zeng, Austin; Sprenger, Ryan J; Kurtz, Courtney C; Suen, Garret; Carey, Hannah V

    2014-09-01

    The gut microbiota plays important roles in animal nutrition and health. This relationship is particularly dynamic in hibernating mammals where fasting drives the gut community to rely on host-derived nutrients instead of exogenous substrates. We used 16S rRNA pyrosequencing and caecal tissue protein analysis to investigate the effects of hibernation on the mucosa-associated bacterial microbiota and host responses in 13-lined ground squirrels. The mucosal microbiota was less diverse in winter hibernators than in actively feeding spring and summer squirrels. UniFrac analysis revealed distinct summer and late winter microbiota clusters, while spring and early winter clusters overlapped slightly, consistent with their transitional structures. Communities in all seasons were dominated by Firmicutes and Bacteroidetes, with lesser contributions from Proteobacteria, Verrucomicrobia, Tenericutes and Actinobacteria. Hibernators had lower relative abundances of Firmicutes, which include genera that prefer plant polysaccharides, and higher abundances of Bacteroidetes and Verrucomicrobia, some of which can survive solely on host-derived mucins. A core mucosal assemblage of nine operational taxonomic units shared among all individuals was identified with an average total sequence abundance of 60.2%. This core community, together with moderate shifts in specific taxa, indicates that the mucosal microbiota remains relatively stable over the annual cycle yet responds to substrate changes while potentially serving as a pool for 'seeding' the microbiota once exogenous substrates return in spring. Relative to summer, hibernation reduced caecal crypt length and increased MUC2 expression in early winter and spring. Hibernation also decreased caecal TLR4 and increased TLR5 expression, suggesting a protective response that minimizes inflammation.

  5. Characterization of the SIRT family of NAD+-dependent protein deacetylases in the context of a mammalian model of hibernation, the thirteen-lined ground squirrel.

    Science.gov (United States)

    Rouble, Andrew N; Storey, Kenneth B

    2015-10-01

    Hibernating mammals employ strong metabolic rate depression to survive the winter, thereby avoiding the high energy costs of maintaining a euthermic lifestyle in the face of low seasonal temperatures and limited food resources. Characteristics of this natural torpor include a significant reduction in body temperature, a shift to a lipid-based metabolism, global suppression of ATP-expensive activities, and the upregulation of selected genes that mediate biochemical reorganization and cytoprotection. Sirtuin (SIRT) proteins, an evolutionarily conserved family of NAD(+)-dependent protein deacetylases, have been shown to play important roles in the post-translational regulation of many metabolic and cytoprotective processes, suggesting a potential function for these enzymes in the control of hibernation. To assess this possibility, protein levels of the seven mammalian SIRTs (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7), total SIRT activity, and the acetylation status of two downstream SIRT targets (SOD2K68 and NF-κB p65K310) were measured in skeletal muscle, liver, brown adipose and white adipose tissues of the hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus) over the course of the torpor-arousal cycle. The analysis revealed tissue-specific responses of different SIRTs at various points throughout hibernation, including a potentially interesting correlation between increased levels of SIRT3 protein, heightened total SIRT activity, and decreased acetylation of SIRT3 downstream target SOD2K68 in skeletal muscle during late torpor. These results provide evidence to suggest a possible role for the SIRT family of protein deacetylases in the regulation of the metabolic and cellular protective pathways that mediate the process of mammalian hibernation.

  6. Step-change in retreat rates on Novaya Zemlya outlet glaciers

    Science.gov (United States)

    Carr, Rachel; Bell, Heather; Killick, Rebecca; Holt, Tom

    2017-04-01

    Arctic ice masses have rapidly lost ice from the mid-1990s, through a combination of negative surface mass balance and accelerated ice discharge from marine-terminating outlet glaciers. In the past decade, substantial mass deficits have been identified on Novaya Zemlya (NVZ), Russian High Arctic, and its outlet glaciers began to retreat rapidly, from 2000 onwards. However, little is known about longer-term glacier behaviour on NVZ, meaning we have limited context for their recent acceleration in retreat. Here, we greatly extend the available record of glacier retreat, and assess multi-decadal glacier response to forcing between 1976 and 2015, using remotely sensed data. Using statistical changepoint analysis, we demonstrate a significant change in retreat rates for many glaciers, during the early 2000s. We also show that retreat slowed on numerous outlets from 2013 onwards, and that some glaciers even began to advance. NVZ glaciers have previously shown step-like changes in retreat rates, so we cannot determine whether this represents a longer-term trend or short-term slow-down, but it warrants future monitoring. We also assessed spatial patterns of retreat and found no significant differences in retreat rates according to coast or ice mass. Instead, the rate and temporal pattern of retreat were strongly dependant on terminus type: outlets terminating in lakes or the ocean retreated significantly faster than those ending on land. Interestingly, retreat rates on marine- and lake-terminating glaciers were not significantly different. However, the lake-terminating glaciers showed very little variation in retreat rates between glacier or over time, whereas the variability was very large on ocean-terminating glaciers. In terms of climatic controls, significant changes in Jul-Sep sea ice on both coasts of NVZ coincide with the onset of more rapid retreat, but there is large internnual variability in the data.

  7. Insights into the Thwaites Glacier grounding zone from Operation IceBridge aerogravity

    Science.gov (United States)

    Tinto, K. J.; Bell, R. E.; Cochran, J. R.; Elieff, S.; Frearson, N.

    2010-12-01

    modeled bathymetry. A good understanding of the bathymetry at and around the grounding line of the major outlet glaciers of West Antarctica is essential to the understanding of their grounding history, the access of sea water to the grounding zone and the distribution of the flow of the ice. These data also provide vital constraints for models of the future of the West Antarctic ice sheet. Jenkins, A, Dutrieux, P, Jacobs, SS, McPhail, SD, Perrett, JR, Webb, AT and White, D (2010). Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat. Nature Geoscience, 3, 468-472.

  8. South Georgia glaciers through periods of fast and slow retreat

    Science.gov (United States)

    Paasche, O.; Bakke, J.; Schaefer, J. M.

    2013-12-01

    Along the Antarctic Peninsula and across the sub-Antarctic islands most glaciers, regardless of size and configuration, are in a state of demise and have been so for several decades. An emerging question is: how unique is this modern retreat when compared to glacier activity in this region during the last 10 000 years, if at all and to what extent? And also, how is this pattern different from the Northern Hemisphere where glaciers generally were small or even absent during the Holocene Optimum (9000-6000 years ago) and expanding after the onset of the Neoglacial (4000 years ago), with a typical late maximum around the Little Ice age (1400-1800 AD)? Here we address these questions in an effort to further our understanding of natural environmental variability in the Southern Hemisphere on time scales, and with a resolution, high enough to capture glacier trends on multi-decadal to centennial time scales. This is accomplished by acquiring and analyzing new terrestrial glacier records from the remote island South Georgia (54-55°S, 36-38°W) covering at least the last 13 000 years. Results from downstream lake sediment archives together with cosmogenic nuclide dating of a complete moraine sequence add new insight to the glacier history of South Georgia. The Hodges cirque glacier, which was mapped and investigated intermittently by the British Antarctic Survey between 1955-1982, was according to our observations present during the entire Holocene, but smaller advances were superimposed on a long-term pattern of retreat. The Hodges, as one of the first glaciers on South Georgia, had completely melted away by 2008, which indicate a retreat of circa 900 meter since early Holocene.

  9. Particularism and the retreat from theory in the archaeology of agricultural origins.

    Science.gov (United States)

    Gremillion, Kristen J; Barton, Loukas; Piperno, Dolores R

    2014-04-29

    The introduction of new analytic methods and expansion of research into previously untapped regions have greatly increased the scale and resolution of data relevant to the origins of agriculture (OA). As a result, the recognition of varied historical pathways to agriculture and the continuum of management strategies have complicated the search for general explanations for the transition to food production. In this environment, higher-level theoretical frameworks are sometimes rejected on the grounds that they force conclusions that are incompatible with real-world variability. Some of those who take this position argue instead that OA should be explained in terms of local and historically contingent factors. This retreat from theory in favor of particularism is based on the faulty beliefs that complex phenomena such as agricultural origins demand equally complex explanations and that explanation is possible in the absence of theoretically based assumptions. The same scholars who are suspicious of generalization are reluctant to embrace evolutionary approaches to human behavior on the grounds that they are ahistorical, overly simplistic, and dismissive of agency and intent. We argue that these criticisms are misplaced and explain why a coherent theory of human behavior that acknowledges its evolutionary history is essential to advancing understanding of OA. Continued progress depends on the integration of human behavior and culture into the emerging synthesis of evolutionary developmental biology that informs contemporary research into plant and animal domestication.

  10. The retreat from locative overgeneralisation errors: a novel verb grammaticality judgment study.

    Science.gov (United States)

    Bidgood, Amy; Ambridge, Ben; Pine, Julian M; Rowland, Caroline F

    2014-01-01

    Whilst some locative verbs alternate between the ground- and figure-locative constructions (e.g. Lisa sprayed the flowers with water/Lisa sprayed water onto the flowers), others are restricted to one construction or the other (e.g. *Lisa filled water into the cup/*Lisa poured the cup with water). The present study investigated two proposals for how learners (aged 5-6, 9-10 and adults) acquire this restriction, using a novel-verb-learning grammaticality-judgment paradigm. In support of the semantic verb class hypothesis, participants in all age groups used the semantic properties of novel verbs to determine the locative constructions (ground/figure/both) in which they could and could not appear. In support of the frequency hypothesis, participants' tolerance of overgeneralisation errors decreased with each increasing level of verb frequency (novel/low/high). These results underline the need to develop an integrated account of the roles of semantics and frequency in the retreat from argument structure overgeneralisation.

  11. The retreat from locative overgeneralisation errors: a novel verb grammaticality judgment study.

    Directory of Open Access Journals (Sweden)

    Amy Bidgood

    Full Text Available Whilst some locative verbs alternate between the ground- and figure-locative constructions (e.g. Lisa sprayed the flowers with water/Lisa sprayed water onto the flowers, others are restricted to one construction or the other (e.g. *Lisa filled water into the cup/*Lisa poured the cup with water. The present study investigated two proposals for how learners (aged 5-6, 9-10 and adults acquire this restriction, using a novel-verb-learning grammaticality-judgment paradigm. In support of the semantic verb class hypothesis, participants in all age groups used the semantic properties of novel verbs to determine the locative constructions (ground/figure/both in which they could and could not appear. In support of the frequency hypothesis, participants' tolerance of overgeneralisation errors decreased with each increasing level of verb frequency (novel/low/high. These results underline the need to develop an integrated account of the roles of semantics and frequency in the retreat from argument structure overgeneralisation.

  12. Using a professional writing retreat to enhance professional publications, presentations, and research development with staff nurses.

    Science.gov (United States)

    Horstman, Patricia; Theeke, Laurie

    2012-01-01

    This article presents the outcomes of a structured writing retreat used with a group of professional nurses from a Magnet-designated hospital. The purpose of the retreat was to enhance nurses' ability to prepare poster presentations, develop manuscripts for peer-reviewed journal submissions, and design new research studies. This staff development retreat can serve as an exemplar for other hospitals desiring to increase dissemination of best practice.

  13. Comparison of ProTaper and Mtwo retreatment systems in the removal of resin-based root canal obturation materials during retreatment.

    Science.gov (United States)

    Iriboz, Emre; Sazak Öveçoğlu, Hesna

    2014-04-01

    To evaluate the effectiveness of the ProTaper and Mtwo retreatment systems for removal of resin-based obturation techniques during retreatment. A total of 160 maxillary anterior teeth were enlarged to size 30 using ProTaper and Mtwo rotary instruments. Teeth were randomly divided into eight groups. Resilon + Epiphany, gutta-percha + Epiphany, gutta-percha + AH Plus and gutta-percha + Kerr Pulp Canal Sealer (PCS) combinations were used for obturation. ProTaper and Mtwo retreatment files were used for removal of root canal treatments. After clearing the roots, the teeth were split vertically into halves, and the cleanliness of the canal walls was determined by scanning electron microscopy. Specimens obturated with gutta-percha and Kerr PCS displayed significantly more remnant obturation material than did specimens filled with resin-based obturation materials. Teeth prepared with Mtwo instruments contained significantly more remnant filling material than did teeth prepared with ProTaper. ProTaper files were significantly faster than Mtwo instruments in terms of the mean time of retreatment and time required to reach working length. The Resilon + Epiphany and AH Plus + gutta-percha obturation materials were removed more easily than were the Epiphany + gutta-percha and Kerr PCS + gutta-percha obturation materials. Although ProTaper retreatment files worked faster than did Mtwo retreatment files in terms of removing root canal obturation materials, both retreatment systems are effective, reliable and fast.

  14. Scientific retreats with 'speed dating': networking to stimulate new interdisciplinary translational research collaborations and team science.

    Science.gov (United States)

    Ranwala, Damayanthi; Alberg, Anthony J; Brady, Kathleen T; Obeid, Jihad S; Davis, Randal; Halushka, Perry V

    2017-02-01

    To stimulate the formation of new interdisciplinary translational research teams and innovative pilot projects, the South Carolina Clinical and Translational Research (SCTR) Institute (South Carolina Clinical and Translational Science Award, CTSA) initiated biannual scientific retreats with 'speed dating' networking sessions. Retreat themes were prioritized based on the following criteria; cross-cutting topic, unmet medical need, generation of novel technologies and methodologies. Each retreat begins with an external keynote speaker followed by a series of brief research presentations by local researchers focused on the retreat theme, articulating potential areas for new collaborations. After each session of presentations, there is a 30 min scientific 'speed dating' period during which the presenters meet with interested attendees to exchange ideas and discuss collaborations. Retreat attendees are eligible to compete for pilot project funds on the topic of the retreat theme. The 10 retreats held have had a total of 1004 participants, resulted in 61 pilot projects with new interdisciplinary teams, and 14 funded projects. The retreat format has been a successful mechanism to stimulate novel interdisciplinary research teams and innovative translational research projects. Future retreats will continue to target topics of cross-cutting importance to biomedical and public health research. Copyright © 2016 American Federation for Medical Research.

  15. The 22nd annual prostate cancer foundation scientific retreat report.

    Science.gov (United States)

    Miyahira, Andrea K; Simons, Jonathan W; Soule, Howard R

    2016-09-01

    The 22nd Annual Prostate Cancer Foundation (PCF) Scientific Retreat was convened in Washington, D.C. from October 8 to 10, 2015. This event is the foremost scientific conference in the world focusing on basic, translational, and clinical prostate cancer research with the highest potential for accelerating the understanding of prostate cancer biology and improving the lives and outcomes of prostate cancer patients. Topics highlighted during the 2015 Retreat included: (i) new strategies and treatments for localized high-risk, hormone-naïve, oligometastatic, castrate-resistant, and treatment-refractory prostate cancer settings; (ii) the biology and genomics of tumor heterogeneity and tumor evolution; (iii) new understandings on the mechanisms and targeting of oncogenic drivers of prostate cancer; (iv) bioengineering of novel therapies and drug delivery methods; (v) innovative approaches to tumor immunotherapy; (vi) emerging molecular imaging technologies with improved sensitivity and specificity; and (vii) advancements in prognostic and predictive biomarkers and precision medicine strategies. Prostate 76:1037-1052, 2016. © 2016 Wiley Periodicals, Inc.

  16. A Palaeohydrological Shift during Neogene East Antarctic Ice Sheet Retreat

    Science.gov (United States)

    Rees-Owen, R. L.; Newton, R.; Ivanovic, R. F.; Francis, J.; Tindall, J. C.; Riding, J. B.

    2015-12-01

    The East Antarctic Ice Sheet is an important driver of global climate, playing a particular role in governing albedo and atmospheric circulation (eg. Singh et al., 2013). Recent evidence from marine sediment and terrestrial glaciovolcanic sequences suggests that the EAIS underwent periodic retreat and collapse in response to warmer climates during the late Neogene (14 to 3 million years ago). Mummified prostrate trees recovered from palaeosols at Oliver Bluffs in the Beardmore Glacier region, Transantarctic Mountains (85° S), represent a rare insight into the terrestrial palaeoclimate during one of these periods of retreat. Prostrate trees are an understudied but useful tool for interrogating endmember (e.g. periglacial) environments at high altitudes and latitudes. We present exciting new palaeoclimate data from the sequence at Oliver Bluffs. δ18O analysis of tree ring cellulose suggests that Antarctic summer palaeoprecipitation was enriched relative to today (-25 to -5‰ for ancient, -35 to -20‰ for modern); consistent with our isotope-enabled general circulation model simulations. The MBT/CBT palaeothermometer gives a summer temperature of 3-6ºC, consistent with other palaeobotanical climate indices. These geological and model data have wide-ranging implications for our understanding of the hydrological cycle during this time period. We present data suggesting that changes in moisture recycling and source region indicate a markedly different hydrological cycle.

  17. Evaluation of surface alterations in different retreatment nickel-titanium files: AFM and SEM study.

    Science.gov (United States)

    Can Sağlam, Baran; Görgül, Güliz

    2015-05-01

    The aim of this study was to evaluate the surface changes of nickel titanium (Ni-Ti) rotary retreatment files after three and five uses. Furthermore, the effects of 2% sodium hypochlorite and chloroform solutions and sterilization procedures on the NiTi rotary retreatment surfaces were investigated. ProTaper Retreatment files, R-endo files, and Mtwo retreatment files were used for this study. The palatinal roots of maxillary molar teeth were obturated with gutta percha and Ah26. Retreatment procedures were performed with these retreatment file systems. The surface changes of untreated NiTi rotary files that were used three and five times, immersed in NaOCl and chloroform and subjected to sterilization procedures were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The RMS values, three dimensional images and SEM images at various magnifications were obtained. RMS values showed that all three NiTi rotary retreatment file systems showed significant deteriorations after three and five uses. Cracks, damages and spiral construction deteriorations were detected in the SEM images after three and five uses. Furthermore, the Mtwo 15 file was broken off after five uses. AFM data indicated that 2% NaOCl caused significant surface deteriorations on NiTi rotary files and both AFM and SEM evaluation showed that chloroform solution and sterilization procedures did not cause significant surface deteriorations. In conclusion, ProTaper retreatment, R-endo, and Mtwo retreatment files showed surface damages depending on retreatment procedures. Clinicians have to consider that retreatment files always have a tendency to break off after the third time they have been used.

  18. The writing retreat: a high-yield clinical faculty development opportunity in academic writing.

    Science.gov (United States)

    Cable, Christian T; Boyer, Debra; Colbert, Colleen Y; Boyer, Edward W

    2013-06-01

    The need for consistent academic productivity challenges junior clinician-scholars, who often lack the aptitude to ensure efficient production of manuscripts. To solve this problem, an academic division of a major medical center developed an off-site writing retreat. The purpose of the retreat was not to teach writing skills, but to offer senior mentor assistance with a focus on the elements of manuscript writing. The retreat paired senior faculty members with junior staff. Senior faculty identified manuscript topics and provided real-time writing and editing supervision. Team-building exercises, midcourse corrections, and debriefing interviews were built into the retreat. The number of manuscripts and grant proposals generated during the 2008-2011 retreats was recorded, and the program was evaluated by using unstructured debriefing interviews. An average of 6 to 7 faculty members and fellows participated in each retreat. During the past 4 years, participants produced an average of 3 grant proposals and 7 manuscripts per retreat. After the writing retreat, each fellow and junior faculty member produced an average of 4 scholarly products per year, compared to fewer than 2 for prior years' retreats. Participant feedback indicated the success of the retreat resulted from protected time, direct mentorship by the scholars involved, and pairing of authors, which allows for rapid production of manuscripts and accelerated the editing process. More than 80% of mentors returned each year to participate. The writing retreat is a feasible, effective strategy to increase scholarship among faculty, acceptable to mentees and mentors, and sustainable over time.

  19. 110 kV双回线路管型复合材料杆避雷线架设与接地方案研究%Erection Scheme of Overhead Grounding Wire on Composite Material Pole and Its Grounding for 110 kV Double Circuit Overhead Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    李志军; 陈维江; 戴敏; 李志政; 李汉明; 邓世聪

    2014-01-01

    我国学者尝试在雷电活动强烈、污秽严重地区的110 kV架空线路应用复合材料绝缘杆,以提高相对地空气间隙距离和爬电距离。然而绝缘水平的提高,复合材料杆还是否需要架设避雷线以及避雷线接地引下线,是防雷面临的关键技术问题之一。针对典型110 kV复合材料杆,对比研究未架设避雷线的复合材料杆与架设避雷线的同电压等级、相同导线高度铁塔线路的雷电性能,考虑2种杆塔线路引雷能力、雷电冲击绝缘强度以及建弧率等因素的差异,发现:2种杆塔线路引雷能力间的差异可以忽略;未架设避雷线的复合材料杆雷电冲击绝缘强度是铁塔的3.5倍,建弧率为铁塔的53%,但是反击耐雷水平仅为24.5 kA,雷击跳闸率高达1.13次/(100 km⋅a),均明显劣于铁塔。据此,推荐110 kV复合材料杆架设避雷线。然后,对比估算避雷线不同接地方案下雷电性能的差异发现:避雷线若不经引下线接地,则复合材料杆雷电性能明显劣于铁塔,但若经引下线逐杆接地,则雷电性能显著优于铁塔。因此,提出避雷线应逐杆接地。综上所述,110 kV 复合材料杆线路防雷接地方案应当采用架设避雷线,且通过金属引下线逐杆接地的设计。%It is attempted for Chinese scholars to apply insulation pole composed of composite material in the erection of 110 kV overhead transmission lines located at the regions with strong lightning activity and/or serious pollution to enhance the phase-to-ground air gap distance and creepage distance effectively. However, with the enhancement of insulation level whether the overhead ground wire should be erected on the composite material pole as well as its grounding downlead should be equipped are key problems that the lightning protection technology has to be faced with. As to the composite material pole for 110 kV transmission lines, the lightning

  20. Testing geographical and climatic controls on glacier retreat

    Science.gov (United States)

    Freudiger, Daphné; Stahl, Kerstin; Weiler, Markus

    2015-04-01

    Glacier melt provides an important part of the summer discharge in many mountainous basins. The understanding of the processes behind the glacier mass losses and glacier retreats observed during the last century is therefore relevant for a sustainable management of the water resources and reliable models for the prediction of future changes. The changes in glacier area of 49 sub-basins of the Rhine River in the Alps were analyzed for the time period 1900-2010 by comparing the glacier areas of Siegfried maps for the years 1900 and 1940 with satellite derived glacier areas for the years 1973, 2003 and 2010. The aim was to empirically investigate the controls of glacier retreat and its regional differences. All glaciers in the glacierized basins retreated over the last 110 years with some variations in the sub-periods. However, the relative changes in glacier area compared to 1900 differed for every sub-basin and some glaciers decreased much faster than others. These observed differences were related to a variety of different potential controls derived from different sources, including mean annual solar radiation on the glacier surface, average slope, mean glacier elevation, initial glacier area, average precipitation (summer and winter), and the precipitation catchment area of the glacier. We fitted a generalized linear model (GLM) and selected predictors that were significant to assess the individual effects of the potential controls. The fitted model explains more than 60% of the observed variance of the relative change in glacier area with the initial area alone only explaining a small proportion. Some interesting patterns emerge with higher average elevation resulting in higher area changes, but steeper slopes or solar radiation resulting in lower relative glacier area changes. Further controls that will be tested include snow transport by wind or avalanches as they play an important role for the glacier mass balance and potentially reduce the changes in glacier

  1. Probabilistic estimation of dune retreat on the Gold Coast, Australia

    Science.gov (United States)

    Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.

    2014-01-01

    Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and

  2. Modeling the Retreat Processes of Salt Marsh Edge

    Science.gov (United States)

    Bendoni, M.; Cappietti, L.; Francalanci, S.; Rinaldi, M.; Solari, L.

    2012-12-01

    Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide coastal areas are being lost. In order to address this problem, experimental observations in a laboratory flume and field measurements in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat, with a focus on the erosion mechanisms caused by the action of wind and tidal waves. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves were generated according to a given wave spectrum. The physical model was constructed with the original soil and plants taken in a marsh of the lagoon of Venice, while the wave climate was reproduced according to field measurements. The experiments were conducted in the case of both unvegetated and vegetated bank: a first set of experiments was carried out considering only tidal wave; in the second, bank models experienced the effect of wind waves superimposed to the tide. The following data were collected during the experiments: wave climate interacting with the bank, flow velocity measurements in the eroded quasi-equilibrium configuration, pressure distribution along bank edge and internal pressure fluctuation and damping due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Subsequent to laboratory activity wave climate was measured close to a marsh edge in the Lagoon of Venice with the aim at identifying wave forcing on the bank surface during a moderate wind event and comparing results with the wave stress experienced by bank models in laboratory tests. Several pressure transducers installed close to the bed were used to collect wave height and wave direction with respect to the edge of the marsh. Laboratory data and field measurement

  3. Writing Retreat Increases Productivity And Community For Women Geoscientists

    Science.gov (United States)

    O'Connell, S.; Holmes, M.

    2011-12-01

    Five, weeklong geoscientist writing retreats have been completed with an NSF ADANCE PAID grant. During the five nights and four and a half days, eight to twenty-four academics have gathered in a rural setting outside of Boston to get to focus on writing papers and proposals while getting to know each other. Participants range in age and experience from graduate students to emeritus professors. Over twenty papers and proposals acknowledge their production, in part to this writing retreat. Impact extends beyond papers as informal mentoring and discussions at meals and in the evenings centers on succeeding in academia. Research and teaching are foremost in the conversation. Post-docs learn strategies for applying for jobs and grants, and senior professors discuss strategies for working with academic administrations, running departments and mentoring students. They also learn new technologies and perspectives from younger participants. Particularly helpful are discussions on work-life balance. Networking opportunities extend beyond the retreat as participants join each other at their home institutions to give seminars, develop research projects and mentor each other's students. All weeks follow the same format. Participants arrive Sunday and meet during an evening welcome reception. Monday is devoted to writing. Tuesday a writing coach is available. In the morning, using examples from the scientific literature, she discusses strategies and techniques for writing clearly at a group session. During the afternoon, participants work with the coach individually or in small groups to improve their own writing projects. Wednesday evening a skill session is offered on a topic of interest. These have included undergraduate research, NSF funding, productive techniques for dealing with conflict, and generational characteristics and attitudes, which can hamper communication. A Thursday evening wrap-up session prepares participants for Friday's departure. We believe that this model

  4. Natural entrainment without dawn and dusk : The case of the European ground squirrel (Spermophilus citellus)

    NARCIS (Netherlands)

    Hut, RA; van Oort, BEH; Daan, S; Oort, Bob E.H. van

    Observational data collected in the field and in enclosures show that diurnal, burrow-dwelling European ground squirrels (Spermophilus citellus) never were above ground during twilight at dawn or at dusk. The animals emerged on average 4.02 h (SD = 0.45) after civil twilight at dawn and retreated in

  5. Natural entrainment without dawn and dusk : The case of the European ground squirrel (Spermophilus citellus)

    NARCIS (Netherlands)

    Hut, RA; van Oort, BEH; Daan, S; Oort, Bob E.H. van

    1999-01-01

    Observational data collected in the field and in enclosures show that diurnal, burrow-dwelling European ground squirrels (Spermophilus citellus) never were above ground during twilight at dawn or at dusk. The animals emerged on average 4.02 h (SD = 0.45) after civil twilight at dawn and retreated in

  6. Efficacy of two rotary retreatment systems in removing Gutta-percha and sealer during endodontic retreatment with or without solvent: A comparative in vitro study.

    Science.gov (United States)

    Bhagavaldas, Moushmi Chalakkarayil; Diwan, Abhinav; Kusumvalli, S; Pasha, Shiraz; Devale, Madhuri; Chava, Deepak Chowdary

    2017-01-01

    The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in the removal of Gutta-percha (GP) and sealer from the root canal walls with or without solvent. Forty-eight extracted human mandibular first premolars were prepared and obturated with GP and AH Plus sealer. Samples were then randomly divided into four groups. Group I was retreated with MtwoR rotary system without solvent, Group II was retreated with MtwoR rotary system with Endosolv R as the solvent, Group III with D-RaCe rotary system without solvent, and Group IV with D-RaCe rotary system and Endosolv R solvent. The cleanliness of canal walls was determined by stereomicroscope (×20) and AutoCAD software. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the data. Results showed that none of the retreatment systems used in this study was able to completely remove the root canal filling material. D-RaCe with or without solvent showed significantly (P > 0.05) less filling material at all levels compared to MtwoR with/without solvent. Within the limitation of the current study, D-RaCe rotary retreatment system is more effective in removing filling material from root canal walls when compared to MtwoR rotary retreatment system.

  7. Comparative evaluation of debris extruded apically by using, Protaper retreatment file, K3 file and H-file with solvent in endodontic retreatment

    Directory of Open Access Journals (Sweden)

    Chetna Arora

    2012-01-01

    Full Text Available Aim: The aim of this study was to evaluate the apical extrusion of debris comparing 2 engine driven systems and hand instrumentation technique during root canal retreatment. Materials and Methods: Forty five human permanent mandibular premolars were prepared using the step-back technique, obturated with gutta-percha/zinc oxide eugenol sealer and cold lateral condensation technique. The teeth were divided into three groups: Group A: Protaper retreatment file, Group B: K3, file Group C: H-file with tetrachloroethylene. All the canals were irrigated with 20ml distilled water during instrumentation. Debris extruded along with the irrigating solution during retreatment procedure was carefully collected in preweighed Eppendorf tubes. The tubes were stored in an incubator for 5 days, placed in a desiccator and then re-weighed. Weight of dry debris was calculated by subtracting the weight of the tube before instrumentation and from the weight of the tube after instrumentation. Data was analyzed using Two Way ANOVA and Post Hoc test. Results : There was statistically significant difference in the apical extrusion of debris between hand instrumentation and protaper retreatment file and K3 file. The amount of extruded debris caused by protaper retreatment file and K3 file instrumentation technique was not statistically significant. All the three instrumentation techniques produced apically extruded debris and irrigant. Conclusion: The best way to minimize the extrusion of debris is by adapting crown down technique therefore the use of rotary technique (Protaper retreatment file, K3 file is recommended.

  8. Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea.

    Science.gov (United States)

    Renner, Martin; Salo, Sigrid; Eisner, Lisa B; Ressler, Patrick H; Ladd, Carol; Kuletz, Kathy J; Santora, Jarrod A; Piatt, John F; Drew, Gary S; Hunt, George L

    2016-09-01

    Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea.

  9. Patients' perceptions, treatment need, and complexity of orthodontic re-treatment

    NARCIS (Netherlands)

    Ren, Yijin; Boxum, Christo; Sandham, John

    2009-01-01

    The aim of the present study was to investigate the subjective perception and objective treatment need and complexity of patients seeking orthodontic re-treatment. One hundred subjects (66 females, 34 males, age 26.7+/-8.2 years) seeking re-treatment were asked to complete a questionnaire which was

  10. GPCR Retreat 2014: a good view leads to many discoveries!

    Science.gov (United States)

    Chidiac, Peter; Hébert, Terence E

    2015-06-01

    The GPCR gods smiled on us last year as the 15th Annual GPCR Retreat was held last October 2nd-4th in Bromont, Québec. The fall colors were at their peak and the meeting attendees were also in fine form. The program was one of the best we have seen at any GPCR-related meeting in years and there was a great deal of excitement about new methodological approaches to understanding receptor biology, new concepts in GPCR signaling and a continued emphasis on translation of these discoveries. This year was also the first year we opened the meeting with a short course on biased agonism and how to measure and analyze it.

  11. Windblown Pliocene diatoms and East Antarctic Ice Sheet retreat.

    Science.gov (United States)

    Scherer, Reed P; DeConto, Robert M; Pollard, David; Alley, Richard B

    2016-09-20

    Marine diatoms in tillites along the Transantarctic Mountains (TAMs) have been used to suggest a diminished East Antarctic Ice Sheet (EAIS) during Pliocene warm periods. Updated ice-sheet modelling shows significant Pliocene EAIS retreat, creating marine embayments into the Wilkes and Aurora basins that were conducive to high diatom productivity and rapid accumulation of diatomaceous sediments. Here we show that subsequent isostatic uplift exposed accumulated unconsolidated marine deposits to wind erosion. We report new atmospheric modelling utilizing Pliocene climate and derived Antarctic landscapes indicating that prevailing mid-altitude winds transported diatoms towards the TAMs, dominantly from extensive emerged coastal deposits of the Aurora Basin. This result unifies leading ideas from competing sides of a contentious debate about the origin of the diatoms in the TAMs and their link to EAIS history, supporting the view that parts of the EAIS are vulnerable to relatively modest warming, with possible implications for future sea-level rise.

  12. The 21st Annual Prostate Cancer Foundation Scientific Retreat report.

    Science.gov (United States)

    Miyahira, Andrea K; Simons, Jonathan W; Soule, Howard R

    2015-08-01

    The 21st Annual Prostate Cancer Foundation (PCF) Scientific Retreat was held from October 23-25, 2014, in Carlsbad, CA. This event is the world's foremost scientific meeting focusing on prostate cancer and brings together leading basic, translational and clinical researchers in prostate cancer and other diverse disciplines to discuss the newest findings most likely to advance the understanding of prostate cancer and the clinical care of prostate cancer patients. This year's meeting highlighted themes including: (i) research integrity and standards for scientific reproducibility; (ii) prostate cancer disparities; (iii) mechanisms and models of prostate cancer progression and dormancy; (iv) mechanisms of therapeutic resistance; and (v) advancements in precision medicine treatments, treatment models, and predictive and prognostic biomarkers.

  13. North Atlantic warming and the retreat of Greenland's outlet glaciers.

    Science.gov (United States)

    Straneo, Fiammetta; Heimbach, Patrick

    2013-12-05

    Mass loss from the Greenland ice sheet quadrupled over the past two decades, contributing a quarter of the observed global sea-level rise. Increased submarine melting is thought to have triggered the retreat of Greenland's outlet glaciers, which is partly responsible for the ice loss. However, the chain of events and physical processes remain elusive. Recent evidence suggests that an anomalous inflow of subtropical waters driven by atmospheric changes, multidecadal natural ocean variability and a long-term increase in the North Atlantic's upper ocean heat content since the 1950s all contributed to a warming of the subpolar North Atlantic. This led, in conjunction with increased runoff, to enhanced submarine glacier melting. Future climate projections raise the potential for continued increases in warming and ice-mass loss, with implications for sea level and climate.

  14. Cleaning and retreatment protocol for a debonded ceramic restoration

    Science.gov (United States)

    Alonso-Pérez-Barquero, Jorge; Bruguera-Álvarez, August; Agustín-Panadero, Rubén; Fons-Font, Antonio

    2015-01-01

    Objectives: The aim of this article is to propose a resin cement cleaning protocol for use before recementing a debonded restoration. Study Design: Ceramic samples were fabricated from IPS d.sign® and IPS e.max Press® and were treated with hydrofluoric acid etching (HF), or HF+silane (S), or HF+S+adhesive or HF+S+A+resin cement. All samples were placed in a furnace at 650º for one minute in order to attempt to pyrolyze the composite. Each step was examined under scanning electron microscopy (SEM). Results: When the cleaning protocol had been performed, it left a clean and retentive surface. Conclusions: If the restoration is placed in a furnace at 650º for one minute, the composite cement will burn or pyrolyze and disappear, allowing conventional retreatment of the ceramic before rebonding. Key words:Ceramic, debond, surface treatment. PMID:25810843

  15. Susceptibility tests to second line drugs and re-treatment of tuberculosis: Revisiting Early Experiences Las pruebas de sensibilidad a drogas de segunda línea y el re-tratamiento de la tuberculosis: Visión retrospectiva de tres estudios

    Directory of Open Access Journals (Sweden)

    Isabel N. De Kantor

    2007-06-01

    Full Text Available The value of susceptibility tests in guiding antituberculous therapy with second-line drugs remains controversial. We reanalyzed three reports regarding the relationship between in vitro susceptibility of Mycobacterium tuberculosis and the clinical outcome of in-patients treated with these drugs at the Muñiz Hospital, Buenos Aires, during the sixties. These patients had been irregularly treated with a standard regimen consisting of isoniazid, streptomycin and PAS; they developed resistance to at least the first two drugs and persisted culture-positive. Susceptibility testing to ethionamide, cycloserine and kanamycin were performed by the proportion method on Löwenstein Jensen medium. Some level of resistance was detected among isolates from patients not previously treated with these drugs, that could be due to cross resistance with previously administered first line structural analogs. However, the studies evidenced significant association between resistance to ethionamide and cycloserine and prior treatment with these drugs. Increased resistanceto all three drugs was detected within the first three months of treatment. In vitro resistance to ethionamide emerged earlier and was the most frequent followed by resistance to cycloserine and kanamycin. The low frequency of resistance to kanamycin could be related to the low dosage of this drug used at that time. Simultaneous resistance to the three agents, but not to two or one drug, appeared to be a marker of treatment failure. An apparent reversion of drug resistance was observed in near 6% of patients, for whom susceptibility tests were repeated on subsequent isolates, indicating this percentage of inconsistency in reproducibility of test results.La correlación entre resultados de pruebas de sensibilidad a drogas antituberculosas de segunda línea y evolución de los pacientes en tratamiento, aún es discutida. Se reanalizan aquí tres estudios realizados en la década del 60, sobre la relaci

  16. Retrievals of ethane from ground-based high-resolution FTIR solar observations with updated line parameters: determination of the optimum strategy for the Jungfraujoch station.

    Science.gov (United States)

    Bader, W.; Perrin, A.; Jacquemart, D.; Sudo, K.; Yashiro, H.; Gauss, M.; Demoulin, P.; Servais, C.; Mahieu, E.

    2012-04-01

    Ethane (C2H6) is the most abundant Non-Methane HydroCarbon (NMHC) in the Earth's atmosphere, with a lifetime of approximately 2 months. C2H6 has both anthropogenic and natural emission sources such as biomass burning, natural gas loss and biofuel consumption. Oxidation by the hydroxyl radical is by far the major C2H6 sink as the seasonally changing OH concentration controls the strong modulation of the ethane abundance throughout the year. Ethane lowers Cl atom concentrations in the lower stratosphere and is a major source of peroxyacetyl nitrate (PAN) and carbon monoxide (by reaction with OH). Involved in the formation of tropospheric ozone and in the destruction of atmospheric methane through changes in OH, C2H6 is a non-direct greenhouse gas with a net-global warming potential (100-yr horizon) of 5.5. The retrieval of ethane from ground-based infrared (IR) spectra is challenging. Indeed, the fitting of the ethane features is complicated by numerous interferences by strong water vapor, ozone and methane absorptions. Moreover, ethane has a complicated spectrum with many interacting vibrational modes and the current state of ethane parameters in HITRAN (e.g. : Rothman et al., 2009, see http://www.hitran.com) was rather unsatisfactory in the 3 μm region. In fact, PQ branches outside the 2973-3001 cm-1 range are not included in HITRAN, and most P and R structures are missing. New ethane absorption cross sections recorded at the Molecular Spectroscopy Facility of the Rutherford Appleton Laboratory (Harrison et al., 2010) are used in our retrievals. They were calibrated in intensity by using reference low-resolution spectra from the Pacific Northwest National Laboratory (PNNL) IR database. Pseudoline parameters fitted to these ethane spectra have been combined with HITRAN 2004 line parameters (including all the 2006 updates) for all other species encompassed in the selected microwindows. Also, the improvement brought by the update of the line positions and intensities

  17. SEISMIC RESPONSE OF LARGE CROSSING TRANSMISSION TOWER-LINE SYSTEM SUBJECTED TO NEAR-FAULT GROUND MOTIONS%大跨越输电塔-线体系的近场脉冲型地震反应分析

    Institute of Scientific and Technical Information of China (English)

    武钢; 翟长海; 李爽; 谢礼立

    2013-01-01

    分析了大跨越输电塔-线体系的动力特性,对比了大跨越输电塔-线体系的近-远场地震反应,研究了大跨越塔-线体系的近场脉冲地震反应规律.结果表明在同幅值的近场脉冲型地震动作用下,大跨越输电塔-线体系的动力反应远大于其在一般地震动下的反应,大跨越输电塔-线体系的近场脉冲型地震反应幅值随地震动脉冲周期增大而增大.将等效脉冲模型引入大跨越输电塔-线体系近场响应分析,结果表明:塔-线体系在等效脉冲作用下的响应与实际地震动相近,将等效脉冲用于分析大跨越输电塔-线体系的地震响应能够弥补实际近场脉冲型地震动数目过少的不足.%Dynamic characteristics of a large crossing transmission tower-line system (LCTTL) are analyzed.The seismic responses of a large crossing transmission tower-line system subjected to near-fault pulse-like ground motions and ordinary ground motions are compared.The characteristics of responses caused by near-fault pulse-like ground motions are presented.It is shown that the seismic responses of LCTL induced by near-fault pulse-like ground motions are severer than the responses subjected to ordinary ground motions.The amplitude of seismic responses increases with the pulse period of near-fault pulse-like ground motions.An equivalent pulse model is introduced to seismic response evaluation of LCTL.The results demonstrate that the equivalent pulse model can capture the important response characteristics of the near-fault records.The application of equivalent pulse model in seismic responses analysis of LCTL can augment the number of near-fault record set.

  18. Do rapidly retreating valley glaciers increase catchment sediment export rates?

    Science.gov (United States)

    Lane, Stuart; Bakker, Maarten; Gabbud, Chrystelle; Micheletti, Natan; Saugy, Jean-Noël

    2016-04-01

    In the face of rapid climate warming, rapid glacier recession should lead to a marked increase in the spatial extent of paraglacial processes operating in glaciated drainage basins. The paraglacial phase has been well established to be transient but there are very few studies of this transient response and what it means for sediment export. There is good reason to expect that glacier recession could increase basin-scale sediment connectivity as: sediment becomes less dependent on glacier surface transport; proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport; and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity. By using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment (sand and gravel) export from a basin with a rapidly retreating valley glacier, the Haut Glacier d'Arolla, from 1977 to 2014. Modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity. Indeed, there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area. More recently, it was possible to show possible temperature control on sediment export, which may only have become apparent because of the progressive development of better sediment connectivity. However, whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet, the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached. We identify two examples of why. First, gullying was also accompanied by the sediment accumulation at the base of moraines

  19. The unsteady nature of sea cliff retreat due to mechanical abrasion, failure and comminution feedbacks

    Science.gov (United States)

    Kline, Shaun W.; Adams, Peter N.; Limber, Patrick W.

    2014-08-01

    Sea cliff retreat is often linked to large waves, heavy precipitation and seismic events, but the specific operative mechanics have not been well constrained. In particular, what is the role of mechanical abrasion by beach sediments in cliff/platform evolution and how does it relate to the episodic nature of cliff retreat observed at certain locations? Here we present a simple, numerical model of sea cliff retreat that incorporates mechanical abrasion of a basal notch, threshold-controlled failure of the cantilevered block, and a feedback mechanism wherein retreat is dependent on the rate of sediment comminution within the surf zone. Using shore platform and cliff characteristics found in two coastal settings (the central California coast and the English North Sea coast), the model produces retreat rates comparable to those observed via field measurements. The highest retreat rates coincide with the steepest shore platforms and increasing wave height. Steeper platforms promote wave access to the cliff toe and, correspondingly, the receding cliff face produces additional accommodation space for the platform beach, preserving the erosive efficacy of the beach sediments. When exposed to energetic wave forcing, the slope of the inner platform segment controls retreat rates for concave platforms, whereas the slope of the outer platform segment exerts greater control for convex platforms. Platform beaches approached a long-term dynamic equilibrium on the concave profiles, leading to more consistent and steady retreat. Platform beaches were ephemeral on convex profiles, mirroring observed sand wave (Ord) migration on the Holderness coast, UK. These findings agree with previous field observations and support mechanical abrasion as a viable cause of temporal heterogeneity in cliff retreat rate for both coastlines.

  20. A Calculation Method of Grounding-Distance Protection Setting for Transmission Lines with Double-Branched Structure%双分叉线路的接地距离保护整定计算

    Institute of Scientific and Technical Information of China (English)

    文安; 王聪; 李建设; 于芮技; 莫天文; 魏承志; 寻斌斌; 李银红

    2014-01-01

    双分叉线路是输电线路增容改建工程中产生的一种特殊结构线路。可以增大线路输送容量,提高走廊利用率,并且节约建设投资,缩短工期,停电时间较短。从双分叉线路结构特点和保护原理入手,分析了双分叉结构对继电保护整定计算的影响。分析表明,对于双分叉线路,采用改建后线路的实际测量参数,或根据原线路参数计算得到的修正参数,及时调整零序补偿系数中的相应一次值,然后按简单线路整定方法进行整定即可,不会造成保护玉段超越误动。为继电保护整定计算工作提供了依据。%Double-branched transmission line is a special structure in the extension and reconstruction of transmission lines.It can be used to increase the capacity of transmission lines, improve transmission corridors' use efficiency, save cost, shorten construction pe-riod and outage time.A model for double-branched lines has been established based on its structure, and on this basis, effect of the double branched structure to selectivity of ground distance protection has been discussed.The analysis shows that, for transmission lines with double-branched structure, it only needs to calculate zero-sequence compensating coefficient with the correct actual meas-ured value of the newly structured lines or the adjusted parameters, that can get reasonable setting values in the light of the original setting calculation method for usual lines.It provides more reasonable principles when determining the grounding distance protection settings.

  1. Attenuation of ground-borne vibration affecting residents near railway. Lines Deliverable 2.1: Exposure response relationships and factors influencing these relationships (Work Package WP1)

    NARCIS (Netherlands)

    Janssen, S.A.; Vos, H.; Koopman, A.

    2014-01-01

    The objective of the present deliverable is to describe and assess reported health impacts of vibration among residents living near railway lines, in particular the response to freight trains. To this end, first a state of the art overview is given of the results from all field studies reported so f

  2. Extinction and ecological retreat in a community of primates

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, B. E.; Godfrey, L. R.; Guilderson, T. P.; Zermeno, P.; Koch, P. L.; Dominy, N. J.

    2012-05-23

    The lemurs of Madagascar represent a prodigious adaptive radiation. At least 17 species ranging from 11 to 160 kg have become extinct during the past 2000 years. The effect of this loss on contemporary lemurs is unknown. The concept of competitive release favours the expansion of living species into vacant niches. Alternatively, factors that triggered the extinction of some species could have also reduced community-wide niche breadth. Here, we use radiocarbon and stable isotope data to examine temporal shifts in the niches of extant lemur species following the extinction of eight large-bodied species. We focus on southwestern Madagascar and report profound isotopic shifts, both from the time when now-extinct lemurs abounded and from the time immediately following their decline to the present. Unexpectedly, the past environments exploited by lemurs were drier than the protected (albeit often degraded) riparian habitats assumed to be ideal for lemurs today. Neither competitive release nor niche contraction can explain these observed trends. We develop an alternative hypothesis: ecological retreat, which suggests that factors surrounding extinction may force surviving species into marginal or previously unfilled niches.

  3. The 20th Annual Prostate Cancer Foundation Scientific Retreat report.

    Science.gov (United States)

    Miyahira, Andrea K; Simons, Jonathan W; Soule, Howard R

    2014-06-01

    The 20th Annual Prostate Cancer Foundation (PCF) Scientific Retreat was held from October 24 to 26, 2013, in National Harbor, Maryland. This event is held annually for the purpose of convening a diverse group of leading experimental and clinical researchers from academia, industry, and government to present and discuss critical and emerging topics relevant to prostate cancer (PCa) biology, and the diagnosis, prognosis, and treatment of PCa patients, with a focus on results that will lend to treatments for the most life-threatening stages of this disease. The themes that were highlighted at this year's event included: (i) mechanisms of PCa initiation and progression: cellular origins, neurons and neuroendocrine PCa, long non-coding RNAs, epigenetics, tumor cell metabolism, tumor-immune interactions, and novel molecular mechanisms; (ii) advancements in precision medicine strategies and predictive biomarkers of progression, survival, and drug sensitivities, including the analysis of circulating tumor cells and cell-free tumor DNA-new methods for liquid biopsies; (iii) new treatments including epigenomic therapy and immunotherapy, discovery of new treatment targets, and defining and targeting mechanisms of resistance to androgen-axis therapeutics; and (iv) new experimental and clinical epidemiology methods and techniques, including PCa population studies using patho-epidemiology.

  4. In Review (Geology): Alpine Landscape Evolution Dominated by Cirque Retreat

    Science.gov (United States)

    Oskin, Michael; Burbank, Doug

    2005-01-01

    Despite the abundance in alpine terrain of glacially dissected landscapes, the magnitude and geometry of glacial erosion can rarely be defined. In the eastern Kyrgyz Range, a widespread unconformity exhumed as a geomorphic surface provides a regional datum with which to calibrate erosion. As tectonically driven surface uplift has progressively pushed this surface into the zone of ice accumulation, glacial erosion has overprinted the landscape. With as little as 500 m of incision into rocks underlying the unconformity, distinctive glacial valleys display their deepest incision adjacent to cirque headwalls. The expansion of north-facing glacial cirques at the expense of south-facing valleys has driven the drainage divide southwards at rates up to 2 to 3 times the rate of valley incision. Existing ice-flux-based glacial erosion rules incompletely model expansion of glacial valleys via cirque retreat into the low-gradient unconformity remnants. Local processes that either directly sap cirque headwalls or inhibit erosion down-glacier appear to control, at least initially, alpine landscape evolution.

  5. Historical analysis and visualization of the retreat of Findelengletscher, Switzerland, 1859-2010

    Science.gov (United States)

    Rastner, P.; Joerg, P. C.; Huss, M.; Zemp, M.

    2016-10-01

    Since the end of the Little Ice Age around 1850, glaciers in Europe have strongly retreated. Thanks to early topographic surveys in Switzerland, accurate maps are available, which enable us to trace glacier changes back in time. The earliest map for all of Switzerland that is usable for a detailed analysis is the Dufour map from around 1850 with subsequent topographic maps on a ~ 20 year interval. Despite the large public and scientific interest in glacier changes through time, this historic dataset has not yet been fully utilized for topographic change assessment or visualization of historic glacier extents. In this study, we use eleven historical topographic maps and more recent digital datasets for the region of Zermatt to analyze geometric changes (length, area and volume) of Findelengletscher as well as for creating animations of glacier evolution through time for use in public communication. All maps were georeferenced, the contour lines digitized, and digital elevation models (DEMs) created and co-registered. Additional digital data like the SRTM X-band DEM and high resolution laser scanning data were used to extend the analysis until 2010. Moreover, one independent DEM from aerial photogrammetry was used for comparison. During the period 1859-2010, Findelengletscher lost 3.5 km of its length (6.9 km in 2010), 4.42 ± 0.13 km2 of its area (15.05 ± 0.45 km2 in 2010) and 1.32 ± 0.52 km3 of its volume. The average rate of thickness loss is 0.45 ± 0.042 m yr- 1 for the 151 years period. Four periods with high thickness change from - 0.56 m ± 0.28 yr- 1 (1859-1881), - 0.40 ± 0.08 m yr- 1 (1937-1965), - 0.90 ± 0.31 m yr- 1 (1995-2000) and - 1.18 ± 0.02 m yr- 1 (2000-2005) have been identified. Small positive thickness changes were found for the periods 1890-1909 (+ 0.09 ± 0.46 m yr- 1) and 1988-1995 (+ 0.05 ± 0.24 m yr- 1). During its retreat with intermittent periods of advance, the glacier separated into three parts. The above changes are demonstrated

  6. Simulation study for measurement of horizontal wind profiles in the polar stratosphere and mesosphere using ground-based observations of ozone and carbon monoxide lines in the 230-250 GHz region

    Science.gov (United States)

    Newnham, David A.; Ford, George P.; Moffat-Griffin, Tracy; Pumphrey, Hugh C.

    2016-07-01

    Meteorological and atmospheric models are being extended up to 80 km altitude but there are very few observing techniques that can measure stratospheric-mesospheric winds at altitudes between 20 and 80 km to verify model datasets. Here we demonstrate the feasibility of horizontal wind profile measurements using ground-based passive millimetre-wave spectroradiometric observations of ozone lines centred at 231.28, 249.79, and 249.96 GHz. Vertical profiles of horizontal winds are retrieved from forward and inverse modelling simulations of the line-of-sight Doppler-shifted atmospheric emission lines above Halley station (75°37' S, 26°14' W), Antarctica. For a radiometer with a system temperature of 1400 K and 30 kHz spectral resolution observing the ozone 231.28 GHz line we estimate that 12 h zonal and meridional wind profiles could be determined over the altitude range 25-74 km in winter, and 28-66 km in summer. Height-dependent measurement uncertainties are in the range 3-8 m s-1 and vertical resolution ˜ 8-16 km. Under optimum observing conditions at Halley a temporal resolution of 1.5 h for measuring either zonal or meridional winds is possible, reducing to 0.5 h for a radiometer with a 700 K system temperature. Combining observations of the 231.28 GHz ozone line and the 230.54 GHz carbon monoxide line gives additional altitude coverage at 85 ± 12 km. The effects of clear-sky seasonal mean winter/summer conditions, zenith angle of the received atmospheric emission, and spectrometer frequency resolution on the altitude coverage, measurement uncertainty, and height and time resolution of the retrieved wind profiles have been determined.

  7. Comparison of protaper and mtwo retreatment systems for working time in the removal of resin-based root canal obturation materials during retreatment

    OpenAIRE

    İriboz, Emre; Sazak Öveçoğlu, Hesna

    2013-01-01

    Objective: The aim of this study is to evaluate the working time of ProTaper and Mtwo retreatment systems for removal of three different resin-based filling materials during simulated retreatment. Methods: 160 extracted maxillary anterior teeth were enlarged using two different rotary systems; ProTaper and Mtwo. The teeth were randomly divided into 8 groups of 20 specimens each. Six groups were filled with 3 different resin-based obturation materials, two groups were filled with an eugenol-ba...

  8. The 20th century retreat of ice caps in Iceland derived from airborne SAR

    DEFF Research Database (Denmark)

    Magnússon, Eyjólfur; Björnsson, Helgi; Dall, Jørgen

    2005-01-01

    they had all recently surged in 1998 as was presumably the case when the outermost moraines were formed. The major contributor to the area decrease is therefore climate changes in the 20th century even though the glacier retreat has been interrupted by short-lived surges. Moraines associated with most...... of the surges in W-Vatnajokull in the 20th century are observed in the SAR data including the most recent surges in the 1990s. Interestingly no push moraines were observed in front of the surge advance, but the moraines appear when the glaciers start retreating. We estimate that the collective decrease...... of the outlets of western Vatnajokull since maximum Neoglacial extent of each outlet, is log km(2) (6.7%) corresponding to an average retreat of 850 in over a 130 km long margin. In the same period the outlet Slettjokull, in N-Myrdalsjokull, has decreased by 33 km(2) (20%) corresponding to an average retreat...

  9. Contributions of a retreat weekend to the healing and coping of cancer patients' relatives.

    Science.gov (United States)

    Arnaert, Antonia; Gabos, Theresa; Ballenas, Vincent; Rutledge, Robert D H

    2010-02-01

    Relatives play a key role in the daily support and care of cancer patients. This role, however, can negatively affect relatives physically, psychologically, emotionally, and spiritually, challenging their health and well-being. Consequently, this could inhibit relatives' abilities to continue in their roles as caregivers. Although various studies have examined different interventions for the relatives of cancer patients, no formal research has been published on the role that retreat weekends play in their cancer journeys. In this qualitative study we used semistructured interviews to explore the experiences of 8 relatives who attended a "Skills for Healing Retreat Weekend" in Ontario, Canada. The findings indicate that the retreat, in bringing people together to partake in discussions and activities, fostered a sense of community among the participants. The retreat also had enduring effects, contributing to relatives' ongoing processes of healing as well as providing them with strategies for coping in their roles as caregivers.

  10. The St. Ignatius Jesuit Retreat and Training Centre: Cultivating Ecological Awareness and Connection with the Earth

    Science.gov (United States)

    Groen, Janet

    2017-01-01

    This chapter focuses on the role of religiously based spirituality in cultivating environmental awareness and citizenship by examining an adult environmental education program offered at the Ignatius Jesuit Centre, a religious retreat center in Guelph, Canada.

  11. The retreat of multiculturalism in the liberal state: theory and policy.

    Science.gov (United States)

    Joppke, Christian

    2004-06-01

    This article discusses a recent retreat of multiculturalism in the liberal state. This retreat has occurred both at the level of theory and policy. With the help of some recent liberal critiques of multiculturalism, the first part maps out some shortcomings of the notion of minority integration through cultural recognition, particularly with respect to immigrants. The second part discusses a retreat from multiculturalism policies in three states that had been prominently committed to them: Australia, the Netherlands, and Britain. This practical retreat of multiculturalism is due to a variety of factors, their importance differing across cases: the chronic lack of public support for multiculturalism policies; inherent deficits and failures of multiculturalism policies, especially in socio-economic respect; and a new assertiveness of the liberal state to impose liberal principles.

  12. Efficacy of passive ultrasonic irrigation in removing root filling material during endodontic retreatment

    National Research Council Canada - National Science Library

    Carina MICHELON; Marina FRIGHETTO; Pauline Mastella LANG; Mariana De Carlo BELLO; Rafael PILLAR; Geraldo Fagundes SERPA; Carlos Alexandre Souza BIER

    Abstract Introduction The aim of endodontic retreatment is to remove the previous root filling materials completely to allow for the subsequent steps of cleaning, canal shaping and filling replacement...

  13. A regional approach for modeling cliff retreat rate: The Makhteshim Country, Israel

    Science.gov (United States)

    Finzi, Yaron; Harlev, Noam

    2016-10-01

    Cliff retreat rate significantly affect the evolution of landforms and cliff stability. Cliff retreat studies also provide intriguing clues regarding past geomorphic conditions and environmental changes. We hereby present a model to calculate cliff retreat rate based on spatial data of cliff structure and morphology. The model is applied to numerous cliffs in the arid Makhteshim Country, Israel, and results are calibrated using published rates of two local cliffs. The calculated retreat rates confirm previous assertions that the crater cliffs are receding very slowly, but reveal that the rates vary significantly along the cliffs (1-18 cm ky- 1). Results also provide first estimates of retreat rates of other major cliffs in the region including fast retreat rates at the Sede Zin cliff (300-600 cm ky- 1). The proposed model provides a robust analysis to account for local cliff-talus morphology and yields rate estimates representative of current conditions rather than a long-term (geologic) average rate. Results presented constitute important new insights into regional geomorphic processes and on the stability of specific cliff sections within the study area.

  14. Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain.

    Science.gov (United States)

    Hurst, Martin D; Rood, Dylan H; Ellis, Michael A; Anderson, Robert S; Dornbusch, Uwe

    2016-11-22

    Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured (10)Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The (10)Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cm⋅y(-1)) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cm⋅y(-1)). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.

  15. Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

    Science.gov (United States)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.; Anderson, Robert S.; Dornbusch, Uwe

    2016-11-01

    Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured 10Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The 10Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cmṡy-1) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cmṡy-1). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.

  16. Irradiation and Bevacizumab in High-Grade Glioma Retreatment Settings

    Energy Technology Data Exchange (ETDEWEB)

    Niyazi, Maximilian; Ganswindt, Ute; Schwarz, Silke Birgit [Department of Radiation Oncology, Ludwig-Maximilians-University Munich, Munich (Germany); Kreth, Friedrich-Wilhelm; Tonn, Joerg-Christian [Department of Neurosurgery, Ludwig-Maximilians-University Munich, Munich (Germany); Geisler, Julia; Fougere, Christian la [Department of Nuclear Medicine, Ludwig-Maximilians-University Munich, Munich (Germany); Ertl, Lorenz; Linn, Jennifer [Department of Neuroradiology, Ludwig-Maximilians-University Munich, Munich (Germany); Siefert, Axel [Department of Radiation Oncology, Ludwig-Maximilians-University Munich, Munich (Germany); Belka, Claus, E-mail: claus.belka@med.uni-muenchen.de [Department of Radiation Oncology, Ludwig-Maximilians-University Munich, Munich (Germany)

    2012-01-01

    Purpose: Reirradiation is a treatment option for recurrent high-grade glioma with proven but limited effectiveness. Therapies directed against vascular endothelial growth factor have been shown to exert certain efficacy in combination with chemotherapy and have been safely tested in combination with radiotherapy in a small cohort of patients. To study the feasibility of reirradiation combined with bevacizumab treatment, the toxicity and treatment outcomes of this approach were analyzed retrospectively. Patients and Methods: After previous treatment with standard radiotherapy (with or without temozolomide) patients with recurrent malignant glioma received bevacizumab (10 mg/kg intravenous) on Day 1 and Day 15 during radiotherapy. Maintenance therapy was selected based on individual considerations, and mainly bevacizumab-containing regimens were chosen. Patients received 36 Gy in 18 fractions. Results: The data of the medical charts of the 30 patients were analyzed retrospectively. All were irradiated in a single institution and received either bevacizumab (n = 20), no additional substance (n = 7), or temozolomide (n = 3). Reirradiation was tolerated well, regardless of the added drug. In 1 patient treated with bevacizumab, a wound dehiscence occurred. Overall survival was significantly better in patients receiving bevacizumab (p = 0.03, log-rank test). In a multivariate proportional hazards Cox model, bevacizumab, Karnovsky performance status, and World Health Organization grade at relapse turned out to be the most important predictors for overall survival. Conclusion: Reirradiation with bevacizumab is a feasible and effective treatment for patients with recurrent high-grade gliomas. A randomized trial is warranted to finally answer the question whether bevacizumab adds substantial benefit to a radiotherapeutic retreatment setting.

  17. Why is there no Universal Law for Rock Wall Retreat?

    Science.gov (United States)

    Krautblatter, Michael; Moore, Jeffrey

    2016-04-01

    Comparing studies of rock slope erosion and soil slope erosion, we find no governing equation similar to the universal soil loss equation for rock slopes. Rock masses in contact with the atmosphere are affected by a suite of physical, chemical and biological processes which degrade intact rock, creating new fractures and extending existing flaws. Complex feedbacks must be explored between changing slope boundary conditions, stress redistribution and fracturing, and weathering by external mechanisms. Rock slope systems are distinguished from soil slope systems by the fundamental nonlinear properties of rock masses. Rock masses represent discontinuous, inhomogeneous, anisotropic, and nonlinearly elastic materials, and contain a record of millions of years of thermal, hydrological, mechanical and chemical (THMC) processes. The origin and evolution of rock mass strength over time can significantly affect bedrock erodibility and engineering performance, the study of which represents a major chance and challenge for the geoscience community. The imprint of THMC processes on rock properties begins with the geological genesis of rocks; however, a significant degree of material behaviour evolves coincidently with the exhumation and evolution of topography. Thus, fracture generation has been investigated as the result of the environmental stress history in geology and geomorphology, partly modulated by incision and topographic stress evolution. Resultant fracture patterns control the degree of discontinuity heterogeneity, anisotropy, and nonlinear mechanical behaviour over millions of years. Here we discuss important novel conceptual approaches to temporally and spatially decipher nonlinear effects on rock slope erosion including incision-related topographic stresses, rock fatigue, paraglacial and paracratering effects etc. and how they could contribute to a more uniform understanding of rockwall retreat.

  18. Mangrove Retreat with Rising Sea-level, Bermuda

    Science.gov (United States)

    Ellison, Joanna C.

    1993-07-01

    Low island mangroves keep up with slow sea-level rise by peat accumulation. Holocene stratigraphic records show that they maintain the same pace as sea-level rise at rates up to 9 cm/100 years. Tide gauge records from Bermuda since 1932 show sea-level rise at a rate of 28 cm/100 years. The largest mangrove area (6·26 acres) at Hungry Bay has for the last 2000 years been building peat at a rate of 8·5 to 10·6 cm/100 years. Retreat of the seaward edge has caused loss of 2·24 acres of mangroves, commencing in the last few hundred years, with a second dieback between 1900 and 1947, and a third dieback in the last decade. The substrate elevation of the seaward margin of mangroves is below mean sea-level, the normal lower limit for mangroves. Present dieback shows problems of erosion indicating that the Bruun Rule of beach erosion with sea-level rise is also appropriate for mangrove swamps. Stratigraphy shows that before 4000 BP sea-level rose at a rate of 25 cm/100 years, from 4000 to 1000 years BP the rate of sea-level rise declined to 6 cm/100 years during which time mangroves established, and in the last 1000 years there was an increase to 14·3 cm/100 years, during which time the mangroves died back. This study indicates that low island mangroves will experience problems with the rates of sea-level rise predicted for the next 50 years.

  19. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 8: An intensive HST, IUE, and ground-based study of NGC 5548

    Science.gov (United States)

    Korista, K.; Alloin, D.; Barr, P.; Clavel, J.; Cohen, R. D.; Crenshaw, D. M.; Evans, I. N.; Horne, K.; Koratkar, A. P.; Kriss, G. A.

    1994-01-01

    We present the data and initial results from a combined HST/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988-89. IUE spectra were obtained once every two days for a period of 74 days beginning on 14 March 1993. During the last 39 days of this campaign, spectroscopic observations were also made with the HST Faint Object Spectrograph (FOS) on a daily basis. Ground-based observations, consisting of 165 optical spectra and 77 photometric observations (both CCD imaging and aperture photometry), are reported for the period 1992 October to 1993 September, although much of the data are concentrated around the time of the satellite-based program. These data constitute a fifth year of intensive optical monitoring of this galaxy. In this contribution, we describe the acquisition and reduction of all of the satellite and ground-based data obtained in this program. We describe in detail various photometric problems with the FOS and explain how we identified and corrected for various anomalies. During the HST portion of the monitoring campaign, the 1350 A continuum flux is found to have varied by nearly a factor of two. In other wavebands, the continuum shows nearly identical behavior, except that the amplitude of variability is larger at shorter wavelengths, and the continuum light curves appear to show more short time-scale variability at shorter wavelengths. The broad emission lines also vary in flux, with amplitudes that are slightly smaller than the UV continuum variations and with a small time delay relative to the UV continuum. On the basis of simple time-series analysis of the UV and optical continuum and emission line light curves, we find (1) that the ultraviolet and optical continuum variations are virtually simultaneous

  20. 单档距走廊法架设高压输电线路对地闪的影响%The Influence on Ground Flash from the HV Transmission Lines Erected with Statistical Method of Single-span Corridor

    Institute of Scientific and Technical Information of China (English)

    黎志锋; 张耀宇; 刘刚; 唐军

    2011-01-01

    基于引雷空间理论及珠三角地区已有输电线路参数,建立了单档距走廊法统计模型,对不同地形环境下输电线路走廊区域的地闪定位数据进行了筛选,分析了输电线路架设前后雷电活动及地闪幅值概率分布规律,并基于有限元-模拟电荷法,对雷云先导与大地均匀静电场在置入输电杆塔前后的电场进行了计算及模拟仿真,分析了输电线路的架设时于地闪分布规律影响.结果表明:在不同地形环境下输电线路所产生的对于雷击落点的吸引效应是不同的,在山地环境下最为明显.%Based on the theory of attractive volume of lightning and the parameters of existing transmission lines of the Pearl River Delta region, the statistical method of single-span corridor is established in this paper. Selecting the lightning location data of the corridor area of transmission line in various terrain environments, the paper analyzes the probability distribution of lightning activity and lightning current amplitude before and after the erection of HV transmission lines, and makes calculation and simulation on the electrostatic fields of lightning leader and ground for the both cases based on finite element-charge simulation method to analyze the influence on ground flash from the HV transmission lines erected with statistical method of single-span corridor. The results show that the attractive effect from the transmission line is different in various terrain environments, and is greater in mountainous area.

  1. Grounded theory.

    Science.gov (United States)

    Harris, Tina

    2015-04-29

    Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.

  2. Fracture Resistance of Endodontically Retreated Roots After Retreatment Using Self-Adjusting File, Passive Ultrasonic Irrigation, Photon-Induced Photoacoustic Streaming, or Laser.

    Science.gov (United States)

    Kamalak, Aliye; Uzun, Ismail; Arslan, Hakan; Keleş, Ali; Doğanay, Ezgi; Keskin, Cangül; Akçay, Merve

    2016-10-01

    Additional cleaning techniques and devices are required to remove maximum amount of residual filling material, which might limit disinfection of root canal system during retreatment. This study aimed to compare fracture resistance of roots when self-adjusting file (SAF), photon-induced photoacoustic streaming (PIPS), passive ultrasonic irrigation (PUI), erbium-doped yttrium aluminum garnet (Er:YAG), or neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers are applied following the use of retreatment files in endodontics. A total of 117 human mandibular canine teeth of similar dimensions were selected and divided into nine groups (n = 13). Aside from control, instrumented, and only-prepared groups, 91 teeth were remaining, of which 13 were assigned to the only-filling group and final 78 to retreatment, thus R-Endo file, R-Endo+SAF, R-Endo+PUI, R-Endo+Er:YAG laser, R-Endo+Nd:YAG laser, and R-Endo+PIPS. The fracture strengths of the retreatment groups were lower than control, instrumented, and only-filling groups (p  0.05). Further cleaning methods using SAF, PIPS, Er:YAG laser, Nd:YAG laser, or PUI did not decrease the fracture resistance when compared with the R-Endo group.

  3. Collision induced broadening of ν1 band and ground state spectral lines of sulfur dioxide perturbed by N2 and O2

    Science.gov (United States)

    Ceselin, Giorgia; Tasinato, Nicola; Puzzarini, Cristina; Charmet, Andrea Pietropolli; Stoppa, Paolo; Giorgianni, Santi

    2017-09-01

    To monitor the constituents and trace pollutants of Earth atmosphere and understand its evolution, accurate spectroscopic parameters are fundamental information. SO2 is produced by both natural and anthropogenic sources and it is one of the principal causes of acid rains as well as an important component of fine aerosol particles, once oxidized to sulfate. The present work aims at determining SO2 broadening parameters using N2 and O2 as atmospherically relevant damping gases. Measurements are carried out in the infrared (IR) and mm-/sub-mm wave regions, around 8.8 μm and in the 104 GHz-1.1 THz interval, respectively. IR ro-vibrational transitions are recorded by using a tunable diode laser spectrometer, whereas the microwave spectra are recorded by using a frequency-modulated millimeter-/submillimeter-wave spectrometer. SO2-N2 and SO2-O2 collisional cross sections are retrieved for several ν1 band ro-vibrational transitions of 32S16O2, for some transitions belonging to either ν1 + ν2 - ν2 of 32S16O2 or ν1 of 34S16O2 as well as for about 20 pure rotational transitions in the vibrational ground state of the main isotopic species. From N2- and O2- broadening coefficients the broadening parameters of SO2 in air are derived. The work is completed with the study of the dependence of foreign broadening coefficients on the rotational quantum numbers.

  4. Glacier retreat of the Tian Shan and its impact on the urban growth and environment evaluated from satellite remote sensing data

    Science.gov (United States)

    Fu, B. H.; Guo, Q.; Yan, F.; Zhang, J.; Shi, P. L.; Ayinuer, M.; Xue, G. L.

    2017-07-01

    The retreat of mountain glaciers, notably in high Asia, provides evidence for the rise of global temperature. The mass balance is vital for the health of a glacier. If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice loss due to melting or lies in the ablation zone, the glacier will advance. Conversely, if the accumulation is less than the ablation, the glacier will retreat. Glaciers in retreat will have negative mass balances, and if they do not reach an equilibrium between accumulation and ablation, will eventually disappear. Long-term changes of the mountain glaciers in the Tian Shan, Central Asia, are not well constrained. Analyses of satellite remote sensing data combined with the ground observations reveal a 37.5% decline of glaciered area from 1989 to 2014 in No.1 Glacier, the headwaters of the Urumqi River basin, Chinese Tian Shan, which could be linked to increased summer melting. The results show that the area of glaciers was reduced from 31.55 km2 in 18 August 1989 to 28.66 km2 in 24 August 1994 and 19.74 km2 in 31 August 2014. The glacier area was reduced by 0.47 km2/per year in recent 25 years since 1989, and the annual reduction was 1.5%. Meanwhile, the urban area of Urumqi, the biggest city of Xinjiang Uygur Autonomous Region, increased from 156 km2 in 1989 to 555 km2 in 2014. Correspondingly, the population of permanent residents increased from 1.06 million in 1989 to 3.53 million in 2014. We suggest that the decline of glacier area is driven primarily by summer melting and, possibly, linked to the combined effects of the global rise in temperatures and black carbon/CO2 emission from coal-fired power plants, cement plants and petroleum chemical plants from the nearby Urumqi and surrounding regions. The continuing retreat of glaciers will have a number of different quantitative impacts. Populations in the arid Central Asia regions are heavily dependent on snow and glacier melt for their irrigation and

  5. 探地雷达法在水工输水隧洞衬砌混凝土检测中的应用%Application of ground-penetrating radar method in detection of lining concrete in hydraulic tunnel

    Institute of Scientific and Technical Information of China (English)

    汪魁峰

    2014-01-01

    The non-destructive test of concrete structure is the importent problem in civil engineering field and is regarded as the key to ensure safety and durability of large concrete construction .Based on the in-troduction of rule and method of non-destructive test on ground-penetrating radar , the paper took hydrau-lic tunnel lining concrete as the measured object , and applied ground-penetrating radar method to test and verify concrete thickness , internal rebar distribution and internal defect .Through the comparison between the detection results by ground-penetrating radar and that by drilling core ,it analyzed the precision and deviation of ground-penetrating radar method .The research shows the results of non-destructive test by ground-penetrating radar method are reliable and can meet the requirement of quality control in construc -tion of engineering , the application of non-destructive test in water conservancy engineering is feasible .%混凝土结构的无损检测是工程界普遍重视的问题,也是保证结构安全的关键。在介绍探地雷达法无损检测原理方法基础上,以水工输水隧洞衬砌混凝土为被测对象,应用探地雷达法对衬砌混凝土厚度、内置钢筋分布、内部缺陷等进行测试、标识,并与钻芯法取芯检测结果比较,分析探地雷达法无损检测数据的精确度和偏差程度。结果表明:探地雷达法无损检测结果可信度高,能满足工程建设质量控制的要求,其在水利工程无损检测的应用是可行的。

  6. Semantics versus Statistics in the Retreat from Locative Overgeneralization Errors

    Science.gov (United States)

    Ambridge, Ben; Pine, Julian M.; Rowland, Caroline F.

    2012-01-01

    The present study investigated how children learn that some verbs may appear in the figure-locative but not the ground-locative construction (e.g., "Lisa poured water into the cup"; "*Lisa poured the cup with water"), with some showing the opposite pattern (e.g., "*Bart filled water into the cup"; "Bart filled the cup with water"), and others…

  7. Psychological effects of a one-month meditation retreat on experienced meditators: the role of nonattachment

    Directory of Open Access Journals (Sweden)

    Jesus Montero-Marin

    2016-12-01

    Full Text Available Background. There are few studies devoted to assessing the impact of meditation-intensive retreats on the well-being, positive psychology and personality of experienced meditators. We aimed to assess whether a 1-month Vipassana retreat: a would increase mindfulness and well-being; b would increase prosocial personality traits; and c whether psychological changes would be mediated and/or moderated by non-attachment.Method. A controlled, non-randomized, pre-post-intervention trial was used. The intervention group was a convenience sample (n=19 of experienced meditators who participated in a 1-month Vipassana meditation retreat. The control group (n=19 comprised matched experienced meditators who did not take part in the retreat. During the retreat, the mean duration of daily practice was 8-9 hours, the diet was vegetarian and silence was compulsory. The Experiences Questionnaire (EQ, Non-Attachment Scale (NAS, Positive and Negative Affect Schedule (PANAS, Satisfaction With Life Scale (SWLS, Temperament Character Inventory Revised (TCI-R-67, Five Facets Mindfulness Questionnaire (FFMQ, Self-Other Four Immeasurables (SOFI and the MINDSENS Composite Index were administered. ANCOVAs and linear regression models were used to assess pre-post changes and mediation/moderation effects.Results. Compared to controls, retreatants showed increases in non-attachment, observing, MINDSENS, positive-affect, balance-affect and cooperativeness; and decreases in describing, negative-others, reward-dependence and self-directedness. Non-attachment had a mediating role in decentring, acting aware, non-reactivity, negative-affect, balance-affect and self-directedness; and a moderating role in describing and positive others, with both mediating and moderating effects on satisfaction with life.Conclusions. A 1-month Vipassana meditation retreat seems to yield improvements in mindfulness, well-being and personality, even in experienced meditators. Non-attachment might

  8. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

    Science.gov (United States)

    Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

    2015-01-01

    The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

  9. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

    Directory of Open Access Journals (Sweden)

    Francesca Pasotti

    Full Text Available The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands, a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii over time driving the benthic assemblages into a more compact trophic structure with

  10. Testing of SIR (a transformable robotic submarine) in Lake Tahoe for future deployment at West Antarctic Ice Sheet grounding lines of Siple Coast

    Science.gov (United States)

    Powell, R. D.; Scherer, R. P.; Griffiths, I.; Taylor, L.; Winans, J.; Mankoff, K. D.

    2011-12-01

    A remotely operated vehicle (ROV) has been custom-designed and built by DOER Marine to meet scientific requirements for exploring subglacial water cavities. This sub-ice rover (SIR) will explore and quantitatively document the grounding zone areas of the Ross Ice Shelf cavity using a 3km-long umbilical tether by deployment through an 800m-long ice borehole in a torpedo shape, which is also its default mode if operational failure occurs. Once in the ocean cavity it transforms via a diamond-shaped geometry into a rectangular form when all of its instruments come alive in its flight mode. Instrumentation includes 4 cameras (one forward-looking HD), a vertical scanning sonar (long-range imaging for spatial orientation and navigation), Doppler current meter (determine water current velocities), multi-beam sonar (image and swath map bottom topography), sub-bottom profiler (profile sub-sea-floor sediment for geological history), CTD (determine salinity, temperature and depth), DO meter (determine dissolved oxygen content in water), transmissometer (determine suspended particulate concentrations in water), laser particle-size analyzer (determine sizes of particles in water), triple laser-beams (determine size and volume of objects), thermistor probe (measure in situ temperatures of ice and sediment), shear vane probe (determine in situ strength of sediment), manipulator arm (deploy instrumentation packages, collect samples), shallow ice corer (collect ice samples and glacial debris), water sampler (determine sea water/freshwater composition, calibrate real-time sensors, sample microbes), shallow sediment corer (sample sea floor, in-ice and subglacial sediment for stratigraphy, facies, particle size, composition, structure, fabric, microbes). A sophisticated array of data handling, storing and displaying will allow real-time observations and environmental assessments to be made. This robotic submarine and other instruments will be tested in Lake Tahoe in September, 2011 and

  11. 大庆地区地面变形对哈齐客专的影响研究%Study on Influence of Ground Deformation in Daqing Region on Harbin-Qiqihaer Passenger Dedicated Line

    Institute of Scientific and Technical Information of China (English)

    甄庆廷

    2013-01-01

    研究目的:哈尔滨至齐齐哈尔客运专线穿过的大庆油田由于高强度注水采油和工业、生活超量开采地下水,致使在油田采区及地下水下降漏斗区产生了不同程度的地面隆起和沉降变形,不均匀地面变形会对高速行驶的列车安全产生一定程度的影响,因此,查明和研究地面变形发生的范围、速率、变形量及对客运专线的影响程度,为设计采取必要的措施提供依据是非常必要的.研究结论:(1)为准确了解大庆地区地面变形规律,应建立地面变形动态监测系统,监测第四系沉降变形和白垩系隆起变形特征.(2)多采用化学驱油方式,控制注水压力,尽量保持压力场的平衡,并对靠近线路的采油井和注水井进行适当迁改.(3)在动态监测的基础上,建立地下水开采、采油注水、地面变形的耦合模型,预测地面变形发生、发展趋势,为铁路工程提供准确的预报预警.通过分析得出随着采油工艺的改进、地下水减采和动态监测系统的建立,大庆地区地面变形会得到有效控制和缓解,不会对哈齐客运专线工程造成较大影响.%Research purposes: The Harbin - Qiqihaer Passenger Dedicated Line passes through the Daqing oilfield in where the ground rises or settles in the oil extraction area and the underground water dropping area because of the high -pressure waterflooding for oil extraction and the over exploitation of groundwater for production and living. The uneven ground deformation maybe influences the safety of high -speed railway. Thus, it is necessary to find out and study the range, speed and deformation volume of the ground deformation and their influence on the passenger dedicated line for providing the reference to the railway design. Research conclusions: (1) For accurately knowing the regulation of the ground deformation of the Daqing area, the dynamic monitoring system for the ground deformation should be established to monitor

  12. Grounded cognition.

    Science.gov (United States)

    Barsalou, Lawrence W

    2008-01-01

    Grounded cognition rejects traditional views that cognition is computation on amodal symbols in a modular system, independent of the brain's modal systems for perception, action, and introspection. Instead, grounded cognition proposes that modal simulations, bodily states, and situated action underlie cognition. Accumulating behavioral and neural evidence supporting this view is reviewed from research on perception, memory, knowledge, language, thought, social cognition, and development. Theories of grounded cognition are also reviewed, as are origins of the area and common misperceptions of it. Theoretical, empirical, and methodological issues are raised whose future treatment is likely to affect the growth and impact of grounded cognition.

  13. Recent glacial retreat in High Asia in China and its impact on water resource in Northwest China

    Institute of Scientific and Technical Information of China (English)

    YAO; Tandong; WANG; Youqing; LIU; Shiying; PU; Jianchen; S

    2004-01-01

    Under the impact of climatic warming, the glaciers in the High Asia in China have been retreating continuously with negative glacial mass balance in recent several decades. The retreat became more intensive in the past 10 years. The spatial pattern of the glacial retreat in the High Asia in China is that the smallest magnitude of retreat is in the inland of the Tibetan Plateau, the magnitude increases from the inland to the margin of the Tibetan Plateau, and the largest magnitude at the margin of the Tibetan Plateau. The glacial retreat in the High Asia in China has an important impact on the water resource of the arid regions in Northwest China. This study shows that the glacial retreat in the 1990s has caused an increase of 5.5% in river runoff in Northwest China. In the Tarim River basin, the increase of river runoff is higher than 5.5%.

  14. Localizing Ground-Penetrating Radar

    Science.gov (United States)

    2014-11-01

    ing Ground-Penetrating Radar (LGPR) uses very high frequency (VHF) radar reflections of underground features to generate base- line maps and then...Innovative ground- penetrating radar that maps underground geological features provides autonomous vehicles with real-time localization. Localizing...NOV 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Localizing Ground-Penetrating Radar 5a. CONTRACT NUMBER

  15. Ground Attenuation of Railroad Noise

    DEFF Research Database (Denmark)

    Makarewicz, R.; Rasmussen, Karsten Bo; Kokowski, P.

    1996-01-01

    The influence of ground effect on railroad noise is described using the concept of the peak A-weighted sound exposure level, and A-weighted sound exposure level. The train is modelled by a continuous line of incoherent point sources that have a cosine directivity. The ground effect is included by...

  16. Age Estimates of Holocene Glacial Retreat in Lapeyrère Bay, Anvers Island, Antarctica

    Science.gov (United States)

    Mead, K. A.; Wellner, J. S.; Rosenheim, B. E.

    2011-12-01

    Lapeyrère Bay is a fjord on the eastern side of Anvers Island, located off the Western Antarctic Peninsula. Anvers island has a maximum elevation of 2400m (comprised of ice overlaying bedrock), and experiences colder temperatures and more precipitation than the South Shetlands, which are ~230km to the north. Two glaciers enter Lapeyrère Bay, one large and vulnerable to avalanching, the Iliad Glacier, and one smaller glacier confined to a northern unnamed cove. Though several research cruises have visited Lapeyrère Bay, very little has been published on the fjord's glacial retreat history or sediment flux. The primary purpose of this study is to reconstruct the glacial retreat and sediment flux histories of Lapeyrère Bay using a SHALDRIL core and standard piston cores for chronology and sedimentary facies analysis, and multibeam swath bathymetry data for identifying seafloor morphological features. Preliminary core data from the proximal northern flank of Lapeyrère Bay show greenish grey sandy mud with scattered pebble and sand lens lithology. A core taken in the distal-most part of the fjord is largely diatomaceous sediment grading into grey silty mud with thin sandy turbidites. Multibeam data has exposed seafloor features including a grounding zone wedge at the entrance of the unnamed cove of northern Lapeyrère Bay, drumlins, glacial lineations, and a glacial outwash fan near the ocean-termination of the Iliad glacier. Additionally, this study seeks to assess the effectiveness of a novel 14C method of dating sediment lacking sufficient calcareous material for carbonate 14C dating. The method being tested is ramped pyrolysis radiocarbon analysis, which dates individual fractions of organic material. It is hypothesized that ramped pyrolysis will improve upon bulk acid insoluble organic material (AIOM) dating, as AIOM can include both autochthonous syndepositionally aged carbon and allochthonous pre-aged carbon, resulting in 14C ages inherently older than the

  17. The Fate of Failed Bank Material and Implications for Lateral Retreat: Lake Tahoe Basin

    Science.gov (United States)

    Simon, A.; Thomas, R. E.

    2009-12-01

    (10 - 30 Pa) than the non root-permeated materials (0.3 - 1.7 Pa). This effect is particularly enhanced along the top surface of the block where the highest critical shear stresses obtained. This is also the location where the above-ground biomass impacts flow resistance, causing a reduction in the shear stress applied to the block. Entrainment of entire blocks does occur, requiring shear stresses from 50 to 120 Pa, using a modified Shields criteria. Based on measurements of block dimensions taken in the summers of 2008 and 2009 along the UTR study reach, although the number of blocks doubled from 13 to 26, hydraulic erosion resulted in a 32% reduction in median block size and a 20% reduction in total block volume. The field experiments conducted here illustrate root-permeated blocks provide for greater hydraulic resistance than in situ bank-toe materials. With bank-toe erosion playing a vital role in streambank stability, these blocks tend to reduce lateral retreat of the bank. Further field tests are being conducted in other regions along with flume studies of the impact of blocks on flow acceleration and shear-stress generation landward of the failed block.

  18. Evaluation of a team-building retreat to promote nursing faculty cohesion and job satisfaction.

    Science.gov (United States)

    Birx, Ellen; Lasala, Kathleen B; Wagstaff, Mark

    2011-01-01

    With the growing global shortage of nursing faculty, there is increased need to develop and evaluate strategies to promote nursing faculty job satisfaction. Using quantitative and qualitative research methods, a team-building faculty retreat including challenge course activities was evaluated to determine its effects on group cohesion and job satisfaction. Mean Job in General scores for the sample (n = 29) at the start of the study were comparable with national norms for employees with graduate degrees. There were statistically significant increases in Job in General scores and group cohesion scores from pretest to posttest on the day of the retreat. However, the positive changes were not maintained at the end of the semester when follow-up data were gathered. Content analysis of the retreat day reflections revealed the following themes: getting to know each other better, seeing commonalities and differences, spending time together, developing trust, and working as a group. Several themes were identified in the end of the semester reflections: getting to know each other, feeling closer as a group, setting a friendlier tone for the semester, and that the retreat was a positive experience. Based on these findings, we recommend the use of a faculty retreat with challenge course activities to promote nursing faculty cohesion and job satisfaction. However, follow-up activities are recommended to maintain positive results over time.

  19. Little Ice Age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia

    Science.gov (United States)

    Rivera, A.; Koppes, M.; Bravo, C.; Aravena, J. C.

    2012-03-01

    Glaciar Jorge Montt (48°20' S/73°30' W), one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI), has experienced the greatest terminal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This retreat has revealed trees laying subglacially until 2003. These trees were dated using radiocarbon, yielding burial ages between 460 and 250 cal yrs BP. The presence of old growth forest during those dates indicates that Glaciar Jorge Montt was upvalley of its present position before the commonly recognized Little Ice Age (LIA) period in Patagonia. The post-LIA retreat was most likely triggered by climatically induced changes during the 20th century; however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a 19.5 km long fjord since 1898, which reaches depths in excess of 390 m. The bathymetry is well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

  20. Effectiveness of traditional meditation retreats: A systematic review and meta-analysis.

    Science.gov (United States)

    Khoury, Bassam; Knäuper, Bärbel; Schlosser, Marco; Carrière, Kimberly; Chiesa, Alberto

    2017-01-01

    An increasing number of studies are investigating traditional meditation retreats. Very little, however, is known about their effectiveness. To evaluate the effectiveness of meditation retreats on improving psychological outcomes in general population. A systematic review of studies published in journals or as dissertations in PSYCINFO, PUBMED, CINAHL or Web of Science from the first available date until October 22, 2016. A total of 20 papers (21 studies, N=2912) were included. Effect-size estimates of outcomes combined suggested that traditional meditation retreats are moderately effective in pre-post analyses (n=19; Hedge's g=0.45; 95% CI [0.35, 0.54], pmeditation styles. Results suggested large effects on measures of anxiety, depression and stress, and moderate effects on measures of emotional regulation and quality of life. As to potential mechanisms of actions, results showed large effects on measures of mindfulness and compassion, and moderate effects on measures of acceptance. In addition, changes in mindfulness levels strongly moderated clinical effect sizes. However, heterogeneity was significant among trials, probably due to differences in study designs, types and duration of the retreats and assessed outcomes, limiting therefore the implications of the results. Meditation retreats are moderately to largely effective in reducing depression, anxiety, stress and in ameliorating the quality of life of participants. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Historical aerial imagery reveals rapid frontal retreat following the 1920's warming in southeast Greenland

    Science.gov (United States)

    Bjork, A. A.; Kjaer, K. H.; Korsgaard, N. J.; Khan, S. A.; Kjeldsen, K. K.; Andresen, C. S.

    2011-12-01

    The Greenland ice sheet (GIS) is undergoing massive changes in its frontal positions, velocity structure, and overall mass balance. Since 2000, marine and terrestrial terminating glaciers in southeast Greenland have experienced dramatic frontal retreat and dynamic thinning in response to increased sea surface and air temperatures. However, little is known about the long term glacier history prior to the satellite era. Here we show a unique record of the frontal history of 132 glaciers in southeast Greenland based on historical aerial and satellite imagery from 1933 to 2010. Our results demonstrate decadal sensitivity to temperature changes with rapid retreat following the early century warming (1919-1932) and glacial advance during a minor, but profound mid century cooling (1955-1972) succeeded by the present warming again leading to massive retreat. One significant finding lies in the similarity of the retreat following the early century warming and the latest decade, with a majority of the 132 glaciers exhibiting larger retreat rates in the early period. Furthermore, during the mid century cooling glaciers in southeast Greenland showed a surprisingly rapid response to the cooling, indicating that stabilization and subsequent advance can occur with a short cooling period. Marine terminating glaciers originating from the GIS experienced the largest frontal fluctuations often out of sync with local glaciers and ice caps indicating a larger coherence with ocean temperatures, whereas local glaciers and ice caps and GIS terrestrial terminating glaciers shows frontal fluctuations closely related to the air temperature.

  2. Orthograde endodontic retreatment of teeth with individual cast posts: Report of two cases

    Directory of Open Access Journals (Sweden)

    Ramić Bojana

    2012-01-01

    Full Text Available Introduction. The failure of primary endodontic treatment is manifested by various clinical symptoms following endodontic therapy or, more frequently, by the development of chronic inflammatory process in the apex region without any subjective symptoms. In case of unfavorable outcome of the primary endodontic treatment, orthograde endodontic retreatment is the method of choice for a prolonged therapy. Outline of Cases. Two female patients, 47 and 44 years old, were presented at the Dental Clinic of Vojvodina for endodontic retreatment of teeth 22, 23 and 13, within the repeated prosthetic restoration. Intraradicular individual cast posts were removed using ultrasonic instruments. Remains of gutta-percha were removed by engine driven rotary re-treatment files, root canals were shaped and cleaned using the crown-down technique, and obturated with gutta-percha and epoxy-resin-based sealer using the lateral compaction technique. Conclusion. When there are metal posts or broken instruments in the root canal, the use of ultrasonic instruments is considered a safe method characterized by negligible tooth substance loss and minimal root damage causing fractures and perforations, and the entire procedure is effective and predictable. Non-surgical orthograde endodontic retreatment, when properly performed in accessible and penetrable root canals, achieves a high cure rate, good and lasting results and eliminates the need for radical procedures, such as apical surgery or tooth extraction. When nonsurgical endodontic retreatment is done, treated teeth must be restored by full coronal coverage as soon as possible, to prevent coronal leakage or fracture.

  3. Influence of solvents on the bond strength of resin sealer to intraradicular dentin after retreatment

    Directory of Open Access Journals (Sweden)

    Marcelo PALHAIS

    Full Text Available Abstract This study evaluated the removal of filling material with ProTaper Universal Rotary Retreatment system (PTR combined with solvents and the influence of solvents on the bond strength (PBS of sealer to intraradicular dentin after canal reobturation. Roots were endodontically treated and distributed to five groups (n = 12. The control group was not retreated. In the four experimental groups, canals were retreated with PTR alone or in combination with xylol, orange oil, and eucalyptol. After filling material removal, two specimens of each group were analysed by SEM and µCT to verify the presence of filling remnants on root canal walls. The other roots were reobturated and sectioned in 1-mm-thick dentin slices that were subjected to the push-out test. Data were analysed by two-way ANOVA and Tukey’s test (α = 0.05. SEM and µCT analysis revealed that all retreatment techniques left filling remnants on canal walls. The control group (3.47 ± 1.21 presented significantly higher (p 0.05, and differed significantly from the group with eucalyptol (1.89 ± 0.63. The solvents reduced the PBS of the sealer to dentin and no retreatment technique promoted complete removal of filling material.

  4. Development and Application of A New Type of Grounding Clamper for Transmission Lines%输电线路新型接地线夹的研制和应用

    Institute of Scientific and Technical Information of China (English)

    洪行军; 方玉群; 赵俊杰

    2015-01-01

    针对高压输电线路检修中存在的接地线导线夹挂设不便、易意外脱落等问题,从结构上进行创新,设计出新型接地线导线夹并简要介绍其结构和使用方法。型式检验和现场试用表明,该导线夹具有挂设简便快速、意外脱落率低、安全可靠等优点,效果显著,具有良好的应用前景。%According to the defect of current ground clamper for high voltage transmission lines such as hook inconvenience and accidental shedding, this paper designs a new type of wire clamper for transmission lines and introduces the structure and application method. Type test and field test show that this clamper is simple and rapid in hooking, low in accidental shedding, safe and reliable, significantly effective and has a good application prospect.

  5. Characterized Fault Model of Scenario Earthquake Caused by the Itoigawa-Shizuoka Tectonic Line Fault Zone in Central Japan and Strong Ground Motion Prediction

    Science.gov (United States)

    Sato, T.; Dan, K.; Irikura, K.; Furumura, M.

    2001-12-01

    Based on the existing ideas on characterizing complex fault rupture process, we constructed four different characterized fault models for predicting strong motions from the most likely scenario earthquake along the active fault zone of the Itoigawa-Shizuoka Tectonic Line in central Japan. The Headquarters for Earthquake Research Promotion in Japanese government (2001) estimated that the earthquake (8 +/- 0.5) has the total fault length of 112 km with four segments. We assumed that the characterized fault model consisted of two regions: asperity and background (Somerville et al., 1999; Irikura, 2000; Dan et al., 2000). The main differences in the four fault models were 1) how to determine a seismic moment Mo from a fault rupture area S, 2) number of asperities N, 3) how to determine a stress parameter σ , and 4) fmax. We calculated broadband strong motions at three stations near the fault by a hybrid method of the semi-empirical and theoretical approaches. A comparison between the results from the hybrid method and those from empirical attenuation relations showed that the hybrid method using the characterized fault model could evaluate near-fault rupture directivity effects more reliably than the empirical attenuation relations. We also discussed the characterized fault models and the strong motion characteristics. The Mo extrapolated from the empirical Mo-S relation by Somerville et al. (1999) was a half of that determined from the mean value of the Wells and Coppersmith (1994) data. The latter Mo was consistent with that for the 1891 Nobi, Japan, earthquake whose fault length was almost the same as the length of the target earthquake. In addition, the fault model using the latter Mo produced a slip amount of about 6 m on the largest asperity, which was consistent with the displacement of 6 m to 9 m per event obtained from a trench survey. High-frequency strong motions were greatly influenced by the σ for the asperities (188 bars, 246 bars, 108 bars, and 134

  6. The high resolution topographic evolution of an active retrogressive thaw slump compiled from a decade of photography, ground surveys, laser scans and satellite imagery

    Science.gov (United States)

    Crosby, B. T.; Barnhart, T. B.; Rowland, J. C.

    2015-12-01

    Remote sensing imagery has enables the temporal reconstruction of thermal erosion features including lakes, shorelines and hillslope failures in remote Arctic locations, yet these planar data limit analysis to lines and areas. This study explores the application of varying techniques to reconstruct the three dimensional evolution of a single thermal erosion feature using a mixture of opportunistic oblique photos, ground surveys and satellite imagery. At the Selawik River retrogressive thaw slump in northwest Alaska, a bush plane collected oblique aerial photos when the feature was first discovered in 2004 and in subsequent years. These images were recently processed via Structure from Motion to generate georeferenced point clouds for the years prior to the initiation of our research. High resolution ground surveys in 2007, 2009 and 2010 were completed using robotic total station. Terrestrial laser scans (TLS) were collected in the summers of 2011 and 2012. Analysis of stereo satellite imagery from 2012 and 2015 enable continued monitoring of the feature after ground campaigns ended. As accurate coregistraion between point clouds is vital to topographic change detection, all prior and subsequent datasets were georeferenced to stable features observed in the 2012 TLS scan. Though this coregistration introduces uncertainty into each image, the magnitudes of uncertainty are significantly smaller than the topographic changes detected. Upslope retreat of the slump headwall generally decreases over time as the slump floor progresses from a highly dissected gully topography to a low relief, earthflow dominated depositional plane. The decreasing slope of the slump floor diminishes transport capacity, resulting in the progressive burial of the slump headwall, thus decreasing headwall retreat rates. This self-regulation of slump size based on feature relief and transport capacity suggests a capacity to predict the maximum size a given feature can expand to before

  7. The ninth annual Ion Channel Retreat, Vancouver, Canada, June 27-29, 2011.

    Science.gov (United States)

    Brugger, Saranna; Garate, Marco; Papaianni, Gina; Volnoukhin, Maria; Zhan, Chris; Gill, Sikander; Liang, Sophia; Liang, Dong

    2011-12-01

    Nine years ago Aurora Biomed Inc. (Vancouver, Canada) committed to gathering the brightest minds and the most innovative research companies at one conference. The Ion Channel Retreat provides a podium for scientific discourse spanning a wide range of ion channel disciplines. This conference has consistently provided a venue for people to share knowledge, exchange ideas, and establish partnerships. This conference continues to expand and grow each year, demonstrating the value of such a conference. Attendees at the 2011 Ion Channel retreat presented ion channel research from 12 different countries, representing research groups located on 5 of the 7 continents. Aurora Biomed's 2011 Retreat covered a variety of topics including Ion Channels as Disease Targets, Ion Channels as Pain Targets, TRP-channels, Ion Channel Screening Technologies, Cardiac Function and Pharmacology, Cardiac Safety and Toxicology, and Structure and Function of Ion Channels.

  8. Skillful seasonal forecasts of Arctic sea ice retreat and advance dates in a dynamical forecast system

    Science.gov (United States)

    Sigmond, M.; Reader, M. C.; Flato, G. M.; Merryfield, W. J.; Tivy, A.

    2016-12-01

    The need for skillful seasonal forecasts of Arctic sea ice is rapidly increasing. Technology to perform such forecasts with coupled atmosphere-ocean-sea ice systems has only recently become available, with previous skill evaluations mainly limited to area-integrated quantities. Here we show, based on a large set of retrospective ensemble model forecasts, that a dynamical forecast system produces skillful seasonal forecasts of local sea ice retreat and advance dates - variables that are of great interest to a wide range of end users. Advance dates can generally be skillfully predicted at longer lead times ( 5 months on average) than retreat dates ( 3 months). The skill of retreat date forecasts mainly stems from persistence of initial sea ice anomalies, whereas advance date forecasts benefit from longer time scale and more predictable variability in ocean temperatures. These results suggest that further investments in the development of dynamical seasonal forecast systems may result in significant socioeconomic benefits.

  9. Patellofemoral pain: proximal, distal, and local factors, 2nd International Research Retreat.

    Science.gov (United States)

    Powers, Christopher M; Bolgla, Lori A; Callaghan, Michael J; Collins, Natalie; Sheehan, Francis T

    2012-06-01

    Patellofemoral pain (PFP) is one of the most common lower extremity conditions seen in orthopaedic practice. The mission of the second International Patellofemoral Pain Research Retreat was to bring together scientists and clinicians from around the world who are conducting research aimed at understanding the factors that contribute to the development and, consequently, the treatment of PFP. The format of the 2.5-day retreat included 2 keynote presentations, interspersed with 6 podium and 4 poster sessions. An important element of the retreat was the development of consensus statements that summarized the state of the research in each of the 4 presentation categories. In this supplement, you will find the consensus documents from the meeting, as well as the keynote addresses, schedule, and platform and poster presentation abstracts.

  10. Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse.

    Science.gov (United States)

    Holloway, Max D; Sime, Louise C; Singarayer, Joy S; Tindall, Julia C; Bunch, Pete; Valdes, Paul J

    2016-08-16

    Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming.

  11. Short-term sea cliff failure events accumulate into long-term cliff retreat signals

    Science.gov (United States)

    Limber, Patrick; Palaseanu-Lovejoy, Monica; Danielson, Jeffrey; Barnard, Patrick

    2017-04-01

    Sea cliff retreat is an episodic process, where sudden landslide events punctuate longer periods of relative cliff stability. Understanding sea cliff behavior is key to defining coastal hazard zones or projecting future retreat due to sea level rise (SLR), when present. But, predicting when a particular landslide will occur, or how large it will be, is exceptionally difficult. As a result, rates of sea cliff retreat are often time-averaged over many individual landslides during a given time interval. Time averaging of episodic processes like cliff retreat has several drawbacks, however. For one, the mean erosion or retreat rate can be heavily biased by the time interval over which it is measured, especially over short time scales (e.g. immediate loss of information about the short-term, seemingly random processes (i.e. landslides) that give rise to them. Is a mean long-term (multiple decades or longer) retreat rate caused by the accumulation of a few large landslides, or many smaller landslides? Or, consider the corollary: can observations of landslide size and frequency be used to infer long-term cliff retreat rates? Fortunately the relationship between landslide area and frequency follows a predictable pattern in which landslide frequency (or probability) is a negative power law function of landslide area. Using on landslide frequency-area relationships determined using cliff edges extracted from 18 LiDAR surveys over a 12-year period in California (USA), we developed a simple cellular automata model of probabilistic cliff failure in order to link long-term and short-term cliff behavior. During a model time step, each alongshore cell on the cliff edge has a failure probability primarily determined by 1) a prescribed landslide frequency-area distribution and 2) beach width, so that the failure probability is lessened for wide beaches and vice versa. Beach width at each cell is determined by relative rates of cliff and beach erosion, driven by, for example, SLR or

  12. Effects of L-Aspartic acid on the step retreat kinetics of calcite

    Science.gov (United States)

    Yoshino, Toru; Kagi, Hiroyuki

    2012-01-01

    Effects of L-Aspartic acid (L-Asp) on step retreat kinetics in the dissolution of calcite were investigated. The step retreat velocities under surface-controlled kinetics were determined from in-situ atomic force microscopic observations using an improved flow-through system. Comparison of the present results with those obtained under a mixed kinetics condition revealed that the addition of L-Asp promotes the transport process in the calcite dissolution through acid-base and/or complex forming reactions in the diffusion boundary layer. Additionally, promotion of the acute and obtuse step retreats by the L-Asp additive was observed under surface-controlled kinetics. This report is the first to clarify that L-Asp promotes surface processes in the dissolution of calcite.

  13. Efficacy of interferon retreatment on interferon-resistant patients with chronic hepatitis C.

    Directory of Open Access Journals (Sweden)

    Egusa K

    2003-06-01

    Full Text Available Chronic Hepatitis C can progress to end-stage liver cirrhosis or hepatocellular carcinoma. Interferon (IFN therapy is effective in clearing the hepatitis C virus and in improving liver histology, however, few patients maintain a sustained response (SR after IFN withdrawal. Immediate retreatment with IFN is therefore considered to be both effective and necessary, especially for patients who do not respond to the initial course of IFN therapy. All 145 patients included in the present study underwent liver biopsy, followed by a first treatment course with various IFNs (alpha2a, alpha2b, alpha, OIF or beta. If hepatitis C virus (HCV RNA was positive after the first treatment, the patient was assigned to one of 3 groups, depending on whether his or her alanine transaminase (ALTlevel was normalized (incomplete response, IR, partially responsive(PR, or non-responsive (NR. After an observational interval of 6 to 76 months, a second IFN treatment was initiated with a higher dose or the same dose of the same IFN for the IR group, and with a different IFN for the PR and NR groups. At 6 months after retreatment with IFN, the overall efficacy of the retreatment was 29.7.% In the case of the IR group, who received the same IFN, the overall efficacy was 45.2%. In patients identified as non-SR after the first treatment, who received a different type of IFN for retreatment, the overall efficacy was 18.6%. Anti-IFN antibody was not detected in most of the breakthrough cases. For some IR patients, retreatment with the same IFN was effective. Anti-IFN antibody was mostly negative, indicating that the same IFN can be used in both the first treatment and retreatment to obtain an SR. Switching to a different IFN was effective for some PR and NR patients, suggesting that changing IFN for such cases is a good therapeutic choice.

  14. The influence of previous non-surgical re-treatment on the outcome of endodontic surgery.

    Science.gov (United States)

    Taschieri, S; Machtou, P; Rosano, G; Weinstein, T; Del Fabbro, M

    2010-01-01

    The aim of this study was to evaluate retrospectively if the outcome of periradicular surgery at four year follow-up can be affected by a previous orthograde re-treatment. Eighty-one patients with 118 endodontically treated teeth who underwent surgical retreatment were divided in three groups. In group OA endodontic re-treatment was feasible and was attempted but, owing to the persistence of clinical symptoms and radiographic lesion, apical surgery was performed 4.8 ± 3.5 months later. In group OF endodontic re-treatment was feasible but was not performed, with subsequent apical surgery. In group ONF endodontic re-treatment was unfeasible, and apical surgery was performed. The treatment outcome was assessed four years postsurgery according to clinical and radiographic criteria. Seventy-six patients (112 teeth) could be evaluated at four years. In the ONF group five anterior maxillary teeth, belonging to three female patients, failed to heal. Three failures in three patients occurred in the OF group. No failure was recorded in the OA group. Three teeth in three patients were classified as uncertain healing in each group. The outcome of group OA resulted significantly better than the other treatment groups for both tooth-based and patient-based analysis. No significant effect was found as related to jaw, tooth type, presence of a post. A significant relation was found with gender (P=0.04). A negative correlation was found between outcome and age (Pearson's coefficient=-0.09), suggesting that the probability of failure increases with age. Orthograde re-treatment prior to apical surgery could be considered a valid alternative to tooth extraction and not an over-treatment.

  15. Monsoon-influenced glacier retreat in the Ladakh Range, Jammu and Kashmir

    Science.gov (United States)

    Chudley, Tom; Miles, Evan; Willis, Ian

    2016-04-01

    While the majority of glaciers in the Himalaya-Karakoram mountain chain are receding in response to climate change, stability and even growth is observed in the Karakoram, where glaciers also exhibit widespread surge-type behaviour. Changes in the accumulation regime driven by mid-latitude westerlies could explain such stability relative to the monsoon-fed glaciers of the Himalaya, but a lack of detailed meteorological records presents a challenge for climatological analyses. We therefore analyse glacier changes for an intermediate zone of the HKH to characterise the transition between the substantial retreat of Himalayan glaciers and the surging stability of Karakoram glaciers. Using Landsat imagery, we assess changes in glacier area and length from 1991-2014 across a ˜140 km section of the Ladakh Range, Jammu and Kashmir. Bordering the surging, stable portion of the Karakoram to the north and the Western Himalaya to the southeast, the Ladakh Range represents an important transitional zone to identify the potential role of climatic forcing in explaining differing glacier behaviour across the region. A total of 878 glaciers are semi-automatically identified in 1991, 2002, and 2014 using NDSI (thresholds chosen between 0.30 and 0.45) before being manually corrected. Ice divides and centrelines are automatically derived using an established routine. Total glacier area for the study region is in line with that Randolph Glacier Inventory (RGI) and ˜25% larger than the GLIMS Glacier Database, which is apparently more conservative in assigning ice cover in the accumulation zone. However, the RGI appears notably less successful in identifying glacier termini. Preliminary analysis of glaciers in our study area suggest an overall areal decline of -17.21±7.50% between 1991-2014., a figure more similar to the Zanskar ranges to the south than the Karakoram to the north. No evidence of surge-type behaviour is observed in the study area over this period. Glaciers tend to be

  16. Opportunities for epilepsy: Outcomes of the Milken Institute State of the Science Retreat.

    Science.gov (United States)

    Dumanis, Sonya B; Riley, Ekemini A U; Briggs, LaTese; Kim, YooRi; Lontok, Erik; Salka, Danielle; Stevens, Melissa

    2017-03-01

    The Milken Institute Center for Strategic Philanthropy has launched a Giving Smarter Program in Epilepsy to inform philanthropists on the state of the science for the epilepsy field, key challenges, and solutions to address them. As part of the program, the Milken Institute Center for Strategic Philanthropy hosted a retreat to identify strategic investments that would accelerate epilepsy research to ultimately improve care. The top three prioritized opportunities from the retreat were to 1) invest in data standards and analytical tool development, 2) support young investigators, and 3) promote cross-sector collaborations especially between basic scientists, preclinical researchers, clinicians, and patients.

  17. Rift in Antarctic Glacier: a Unique Chance to Study Ice Shelf Retreat

    Science.gov (United States)

    Howat, Ian M.; Jezek, Ken; Studinger, Michael; Macgregor, Joseph A.; Paden, John; Floricioiu, Dana; Russell, Rob; Linkswiler, Matt; Dominguez, Roseanne T.

    2012-01-01

    It happened again, but this time it was caught in the act. During the last week of September 2011 a large transverse rift developed across thefloating terminus of West Antarcticas PineIsland Glacier, less than 5 years after its lastlarge calving event, in 2007 (Figure 1). PineIsland Glaciers retreat has accelerated substantiallyin the past 2 decades, and it is nowlosing 50 gigatons of ice per year, or roughly 25 of Antarcticas total annual contributionto sea level rise [Rignot et al., 2008]. The glaciers recent accelerated retreat is likely triggered by ocean warming and increased submarine melting. As such, it is of significant interest to glaciologists and of heightened societal relevance.

  18. The allegheny general modification of the Harvard Breast Cosmesis Scale for the retreated breast.

    Science.gov (United States)

    Trombetta, Mark; Julian, Thomas B; Kim, Yongbok; Werts, E Day; Parda, David

    2009-10-01

    The use of brachytherapy--and to a lesser extent, external-beam radiotherapy--in the management of locally recurrent breast cancer following ipsilateral breast tumor recurrence (IBTR) followed by repeat breast-conservation surgery and irradiation is currently an area of intense study. The current cosmetic scoring system is inadequate to score the outcome resulting from retreatment because it does not account for the cosmetic effect of the initial treatment. We propose a modification of the scale for patients who undergo retreatment--the Allegheny General Modification of the Harvard/NSABP/RTOG scoring scale.

  19. Contrasting evidence of Holocene ice margin retreat, south-western Greenland

    DEFF Research Database (Denmark)

    Levy, L. B.; Larsen, N. K.; Davidson, T. A.

    2017-01-01

    Constraining the Greenland Ice Sheet's (GrIS) response to Holocene climate change provides calibrations for ice sheet models that hindcast past ice margin fluctuations. Ice sheet models predict enhanced ice retreat in south-western Greenland during the middle Holocene; however, few geological...... observations corroborating the extensive retreat are available. We present new data from lake sediment cores from the Isua region, south-western Greenland, which provide constraints on Holocene fluctuations of the GrIS margins. Our data indicate that the main GrIS margin was 30 km west of its present...

  20. In vitro evaluation of efficacy of different rotary instrument systems for gutta percha removal during root canal retreatment

    Science.gov (United States)

    Joseph, Mercy; Malhotra, Amit; Rao, Murali; Sharma, Abhimanyu; Talwar, Sangeeta

    2016-01-01

    Background Complete removal of old filling material during root canal retreatment is fundamental for predictable cleaning and shaping of canal anatomy. Most of the retreatment methods tested in earlier studies have shown inability to achieve complete removal of root canal filling. Therefore the aim of this investigation was to assess the efficacy of three different rotary nickel titanium retreatment systems and Hedstrom files in removing filling material from root canals. Material and Methods Sixty extracted mandibular premolars were decoronated to leave 15 mm root. Specimen were hand instrumented and obturated using gutta percha and AH plus root canal sealer. After storage period of two weeks, roots were retreated with three (Protaper retreatment files, Mtwo retreatment files, NRT GPR) rotary retreatment instrument systems and Hedstroem files. Subsequently, samples were sectioned longitudinally and examined under stereomicroscope. Digital images were recorded and evaluated using Digital Image Analysing Software. The retreatment time was recorded for each tooth using a stopwatch. The area of canal and the residual filling material was recorded in mm2 and the percentage of remaining filling material on canal walls was calculated. Data was analysed using ANOVA test. Results Significantly less amount of residual filling material was present in protaper and Mtwo instrumented teeth (p Protaper instruments also required lesser time during removal of filling material followed by Mtwo instruments, NRT GPR files and Hedstrom files. Conclusions None of the instruments were able to remove the filling material completely from root canal. Protaper universal retreatment system and Mtwo retreatment files were more efficient and faster compared to NRT GPR fles and Hedstrom files. Key words:Gutta-percha removal, nickel titanium, root canal retreatment, rotary instruments. PMID:27703601

  1. Impact of Arctic sea-ice retreat on the recent change in cloud-base height during autumn

    Science.gov (United States)

    Sato, K.; Inoue, J.; Kodama, Y.; Overland, J. E.

    2012-12-01

    Cloud-base observations over the ice-free Chukchi and Beaufort Seas in autumn were conducted using a shipboard ceilometer and radiosondes during the 1999-2010 cruises of the Japanese R/V Mirai. To understand the recent change in cloud base height over the Arctic Ocean, these cloud-base height data were compared with the observation data under ice-covered situation during SHEBA (the Surface Heat Budget of the Arctic Ocean project in 1998). Our ice-free results showed a 30 % decrease (increase) in the frequency of low clouds with a ceiling below (above) 500 m. Temperature profiles revealed that the boundary layer was well developed over the ice-free ocean in the 2000s, whereas a stable layer dominated during the ice-covered period in 1998. The change in surface boundary conditions likely resulted in the difference in cloud-base height, although it had little impact on air temperatures in the mid- and upper troposphere. Data from the 2010 R/V Mirai cruise were investigated in detail in terms of air-sea temperature difference. This suggests that stratus cloud over the sea ice has been replaced as stratocumulus clouds with low cloud fraction due to the decrease in static stability induced by the sea-ice retreat. The relationship between cloud-base height and air-sea temperature difference (SST-Ts) was analyzed in detail using special section data during 2010 cruise data. Stratus clouds near the sea surface were predominant under a warm advection situation, whereas stratocumulus clouds with a cloud-free layer were significant under a cold advection situation. The threshold temperature difference between sea surface and air temperatures for distinguishing the dominant cloud types was 3 K. Anomalous upward turbulent heat fluxes associated with the sea-ice retreat have likely contributed to warming of the lower troposphere. Frequency distribution of the cloud-base height (km) detected by a ceilometer/lidar (black bars) and radiosondes (gray bars), and profiles of potential

  2. Ground Wars

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    Political campaigns today are won or lost in the so-called ground war--the strategic deployment of teams of staffers, volunteers, and paid part-timers who work the phones and canvass block by block, house by house, voter by voter. Ground Wars provides an in-depth ethnographic portrait of two...... infrastructures that utilize large databases with detailed individual-level information for targeting voters, and armies of dedicated volunteers and paid part-timers. Nielsen challenges the notion that political communication in America must be tightly scripted, controlled, and conducted by a select coterie...... of professionals. Yet he also quashes the romantic idea that canvassing is a purer form of grassroots politics. In today's political ground wars, Nielsen demonstrates, even the most ordinary-seeming volunteer knocking at your door is backed up by high-tech targeting technologies and party expertise. Ground Wars...

  3. 7 CFR 1755.402 - Ground resistance measurements.

    Science.gov (United States)

    2010-01-01

    ... ground resistance of electronic equipment such as span line repeaters, carrier terminal equipment... Protection Grounding Fundamentals,” for a comprehensive discussion of ground resistance measurements. (d... electronic equipment, the ground resistance shall not exceed 25 ohms. Where the measured ground...

  4. The retreat of the world's mountain glaciers during recent decades; Le retrait des glaciers de montagne dans le monde au cours des dernieres decennies

    Energy Technology Data Exchange (ETDEWEB)

    Francou, B. [Institut de Recherche pour le Developpement (IRD), Mission de Quito, Equateur - LTHE, 38 - Grenoble (France); Vincent, Ch. [Centre National de la Recherche Scientifique (CNRS), UJF, LGGE, 38 - Grenoble (France)

    2009-08-15

    Glaciers have become essential tools for measuring changes in the global environment. Here, we analyze glacier evolution during the last few decades and we wonder whether the observed retreat remains in the range of glacier fluctuations since the mid-Holocene. The main fluctuations experienced by glaciers during the last millenniums, and particularly during the Little Ice Age (-1300 A.D. to {approx}1860 A.D.), are presented succinctly. The recent 1960-2005 period, well documented both by ground and remote sensing observations, shows important disparities between different massifs concerning the timing and the magnitude of glacier fluctuations, which depend on regional climatic conditions. The links between glacier mass balance evolution and climate is clear when approached from an energy balance but the variables commonly considered are only temperature and precipitation. The strong correlation existing between these variables and the mass balance evolution makes it possible to simulate glaciers in the future in function of distinct climatic scenarios. Modeling glacier retreat for the 21. century is an important goal because it will allow the impacts on water resource and sea level to be assessed. (authors)

  5. Historical aerial imagery reveals rapid frontal retreat following the 1920’s warming in southeast Greenland

    DEFF Research Database (Denmark)

    Bjørk, Anders Anker; Kjær, Kurt H.; Korsgaard, Niels Jákup

    The Greenland ice sheet (GIS) is undergoing massive changes in its frontal positions, velocity structure, and overall mass balance. Since 2000, marine and terrestrial terminating glaciers in southeast Greenland have experienced dramatic frontal retreat and dynamic thinning in response to increased...... demonstrate decadal sensitivity to temperature changes with rapid retreat following the early century warming (1919-1932) and glacial advance during a minor, but profound mid century cooling (1955-1972) succeeded by the present warming again leading to massive retreat. One significant finding lies...... in the similarity of the retreat following the early century warming and the latest decade, with a majority of the 132 glaciers exhibiting larger retreat rates in the early period. Furthermore, during the mid century cooling glaciers in southeast Greenland showed a surprisingly rapid response to the cooling...

  6. Iceland rising: Solid Earth response to ice retreat inferred from satellite radar interferometry and visocelastic modeling

    NARCIS (Netherlands)

    Auriac, A.; Spaans, K.H.; Sigmundsson, F.; Hooper, A.; Schmidt, P.; Lund, B.

    2013-01-01

    A broad uplift occurs in Iceland in response to the retreat of ice caps, which began circa 1890. Until now, this deformation signal has been measured primarily using GPS at points some distance away from the ice caps. Here, for the first time we use satellite radar interferometry (interferometric sy

  7. Climate Driven Retreat of Mount Baker Glaciers and Changing Water Resources

    Directory of Open Access Journals (Sweden)

    Tristram Irvine-Fynn

    2016-08-01

    Full Text Available Reviewed: Climate Driven Retreat of Mount Baker Glaciers and Changing Water Resources By Mauri Pelto. Cham, Switzerland: Springer, 2015. x + 107 pp. Softcover: US$ 54.99, ISBN 978-3-319-22604-0. E-book: US$ 39.99, ISBN 978-3-319-22605-7.

  8. Modeling the retreat of the Jakobshavn Glacier from the LIA and into the future

    Science.gov (United States)

    Steiger, Nadine; Hestnes Nisancioglu, Kerim; Åkesson, Henning; Maghami Nick, Faezeh

    2017-04-01

    Many marine-terminating glaciers on Greenland have experienced rapid retreat and acceleration during the last decades, coinciding with increased air and ocean temperatures. Destabilized marine-terminating glaciers have been capable of discharging vast amounts of ice into the ocean, contributing significantly to sea-level rise. In order to conduct prospective simulations of the glaciers' development and their future contribution to sea-level rise, it is crucial to understand the dynamics and triggers of the past retreat, as well as the relative importance of the external forcing versus fjord geometry. Using an idealized numerical flowband model1,2, we are able to reproduce the documented retreat of the Jakobshavn Glacier, western Greenland, since the Little Ice Age (LIA). Based on the results from the hindcast experiments, we investigate the relative role of climate forcing and fjord geometry on glacier stability and assess the potential for non-linear retreat in the coming 200 years. References: [1] Nick et al. 2009, Nature Geoscience, doi:10.1038/ngeo394. [2] Nick et al. 2013, Nature, doi:10.1038/nature12068

  9. Linking Tarim Basin sea retreat (west China) and Asian aridification in the late Eocene

    NARCIS (Netherlands)

    Bosboom, R.; Dupont-Nivet, G.; Grothe, A.; Brinkhuis, H.; Villa, G.; Mandic, O.; Stoica, M.; Huang, W.; Yang, W.; Guo, Z.; Krijgsman, W.

    2014-01-01

    The Tarim Basin in western China formed the easternmost margin of a shallow epicontinental sea that extended across Eurasia and was well connected to the western Tethys during the Paleogene. Climate modelling studies suggest that the westward retreat of this sea from Central Asia may have been as im

  10. ASPIRE: Formation of Pre-Service Teachers through Leadership, Community Engagement and Retreat Training

    Science.gov (United States)

    Hackett, Chris; Lavery, Shane

    2010-01-01

    This article explores the experiences of pre-service teachers who are involved in a program promoting leadership, community engagement and retreat training. It initially presents a review of the literature on the significant links between teacher commitment and quality teaching. It then describes how four significant dispositions: care,…

  11. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    Science.gov (United States)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  12. Gully head retreat in the sub humid northwestern Ethiopian highlands: the Ene-Chilala catchment

    Science.gov (United States)

    In the northern highlands of Ethiopia, gully erosion is severe. Despite many efforts to implement gully prevention measures, controlling gully erosion remains a challenge. The objective is to better understand the regional gully erosion processes and to prevent gully head retreat. The study was cond...

  13. The Role of Adherence and Retreatment in De Novo Emergence of MDR-TB.

    Science.gov (United States)

    Cadosch, Dominique; Abel Zur Wiesch, Pia; Kouyos, Roger; Bonhoeffer, Sebastian

    2016-03-01

    Treatment failure after therapy of pulmonary tuberculosis (TB) infections is an important challenge, especially when it coincides with de novo emergence of multi-drug-resistant TB (MDR-TB). We seek to explore possible causes why MDR-TB has been found to occur much more often in patients with a history of previous treatment. We develop a mathematical model of the replication of Mycobacterium tuberculosis within a patient reflecting the compartments of macrophages, granulomas, and open cavities as well as parameterizing the effects of drugs on the pathogen dynamics in these compartments. We use this model to study the influence of patient adherence to therapy and of common retreatment regimens on treatment outcome. As expected, the simulations show that treatment success increases with increasing adherence. However, treatment occasionally fails even under perfect adherence due to interpatient variability in pharmacological parameters. The risk of generating MDR de novo is highest between 40% and 80% adherence. Importantly, our simulations highlight the double-edged effect of retreatment: On the one hand, the recommended retreatment regimen increases the overall success rate compared to re-treating with the initial regimen. On the other hand, it increases the probability to accumulate more resistant genotypes. We conclude that treatment adherence is a key factor for a positive outcome, and that screening for resistant strains is advisable after treatment failure or relapse.

  14. 交流线路与+800 kV直流线路同走廊时的地面混合电场研究%Study on the Hybrid Electric Field Over the Ground Surface Under AC Lines and ±800 kV DC Lines in the Same Corridor

    Institute of Scientific and Technical Information of China (English)

    杨勇; 陆家榆; 鞠勇

    2009-01-01

    交流线路与±800 kV直流线路共用走廊的情况将在我困出现,因此需要研究该种线路地面混合电场的计算方法,以满足工程设计和环境保护需要.在分析同走廊架设的交流线路与±800 kV直流线路相互影响的基础上,提出了一种计算该类线路地面混合电场的方法.通过对比使用该方法得到的计算结果与不考虑两种线路相互影响时的计算结果,得到如下结论:相对于忽略交直流线路的相互影响,当考虑其相互影响时,在同走廊交直流线路中心附近,地面混合电场的瞬时最大值横向分布有波动;两种计算方法得到的地面混合电场有效值分布曲线基本重合;在一个交流周期内,同走廊线路地面混合电场的最大值与单独±800 kV直流线路地面合成电场的最大值差别很小.%Parallel adjacent erection of AC transmission lines and ±800 kV DC transmission lines in the same corridor will occur in China, so the calculation method for the hybrid electric field over the ground under this type of lines should be studied so as to satisfy the requirements of engineering design and environmental protection. Based on the analysis of mutual influences between AC transmission lines and ±800 kV DC transmission lines in the same corridor, a calculation method is proposed. Through the comparison between the calculation results achieved with this method and the corresponding calculation results obtained when the mutual influences between AC transmission lines and ±800 kV DC transmission lines are neglected, some conclusions can be drawn as follows: compared with the calculation results obtained when the mutual influences are neglected, near the center of AC transmission lines and ±800 kV DC transmission lines in the same corridor, the lateral distribution of the instantaneous maximal values of the hybrid electric field obtained with the proposed method fluctuates;the lateral distributions of the virtual values of the

  15. Reasons for Retreatment of Amalgam and Composite Restorations among the Patients Referring to Tabriz Faculty of Dentistry

    Directory of Open Access Journals (Sweden)

    Siavash Savadi Oskoee

    2007-06-01

    Full Text Available

    Background and aims. Retreatment of existing restorations not only requires a lot of money and time but also there is a danger of weakening tooth structure and irritating the pulp. Since awareness of the reasons for the retreatment of teeth will save the teeth from possible future failure, the aim of this study was to assess the reasons for retreatment of amalgam and composite restorations in patients referring to Tabriz Faculty of Dentistry.

    Materials and methods. In this descriptive study, the subjects had previously received an amalgam or a composite restoration in the Operative Department by dental students and were judged to need retreatment in their second visit. A total of 300 defective teeth were selected by simple random sampling method. The data was collected through examination and questionnaires and analyzed using chi-square test.

    Results. There was a statistically significant association between the type of the restorative material and the reason for retreatment (p=0.001.

    Conclusion. Although the reasons for the retreatment of amalgam and composite restorations were different, recurrent caries was the main reason for the retreatment for both restorative materials.

  16. Habitat selection in a rocky landscape: experimentally decoupling the influence of retreat site attributes from that of landscape features.

    Science.gov (United States)

    Croak, Benjamin M; Pike, David A; Webb, Jonathan K; Shine, Richard

    2012-01-01

    Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often correlate with their proximity to landscape features). Disentangling this co-variation may facilitate the restoration or conservation of threatened systems. To experimentally examine the role of landscape attributes in determining retreat-site quality for saxicolous ectotherms, we deployed 198 identical artificial rocks in open (sun-exposed) sites on sandstone outcrops in southeastern Australia, and recorded faunal usage of those retreat sites over the next 29 months. Several landscape-scale attributes were associated with occupancy of experimental rocks, but different features were important for different species. For example, endangered broad-headed snakes (Hoplocephalus bungaroides) preferred retreat sites close to cliff edges, flat rock spiders (Hemicloea major) preferred small outcrops, and velvet geckos (Oedura lesueurii) preferred rocks close to the cliff edge with higher-than-average sun exposure. Standardized retreat sites can provide robust experimental data on the effects of landscape-scale attributes on retreat site selection, revealing interspecific divergences among sympatric taxa that use similar habitats.

  17. 客运专线铁路与普通铁路地面信号显示标准的兼容性研究%Research on Compatibility of Ground Signal Indication Criterions between Dedicated Passenger Line and Conventional Railway Line

    Institute of Scientific and Technical Information of China (English)

    石先明

    2016-01-01

    Dedicated passenger line ( DPL ) and conventional railway line are using different technical specifications for ground signal setting and signal indication. When DPL joints conventional railway lines of CTCS2/3 , compatibility problem exists in the junction station and the section in perspective of signal setting and signal indication, which poses threat to normal traffic. The suggested solution is that the starting signal of the junction station uses the starting signal and the normal red-aspect specified for conventional railways, and signal indication criterions for dedicated railway and conventional railway are implemented respectively after the outgoing route is opened. Moreover, the paper studies and presents other programs to improve the compatibility.%目前我国客运专线铁路和普通铁路的地面信号机设置及其信号显示方式分别采用不同的技术标准。当客运专线铁路与CTCS-2/3级普通铁路交汇衔接时,接轨站及其区间的地面信号机设置及其显示方式存在兼容性问题,给铁路运输造成安全隐患。推荐的解决方案是:接轨站出站信号机采用普通铁路标准的出站信号机机构和常态点红灯方式,开放发车进路后分别执行普通铁路和客运专线铁路的信号显示标准。另外,文中还研究提出了可进一步完善兼容性的其他改进方案。

  18. Transmission Lines or Poles, Electric, Electricity Transmission Lines; electran; Major above ground high voltage electrical transmission lines as shown on USGS 7.5 minute topo quads and/or as confirmed through identification of visible right of way cuts on digital orthophotgraphy., Published in 2001, 1:4800 (1in=400ft) scale, State of Rhode Island and Providence Plantations.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Transmission Lines or Poles, Electric dataset, published at 1:4800 (1in=400ft) scale, was produced all or in part from Orthoimagery information as of 2001. It...

  19. Retreatment and outcomes of recurrent intracranial vertebral artery dissecting aneurysms after stent assisted coiling: a single center experience.

    Directory of Open Access Journals (Sweden)

    Ying Song

    Full Text Available The retreatment of recurrent intracranial vertebral artery dissecting aneurysms (VADAs after stent assisted coiling (SAC has not yet been studied. The purpose of this study was to evaluate the strategies and outcomes for retreatment of recurrent VADAs after SAC.Between September 2009 and November 2013, six consecutive patients presenting with recurrent intracranial VADAs after SAC were enrolled in this study. They were all male with age ranging from 29 to 54 years (mean age, 46.2 years. The procedures of treatments and angiographic and clinical follow-up were reviewed retrospectively. Retreatment modalities were selected individually according to the characteristics of recurrence. The outcomes of retreatment were evaluated by angiographic and clinical follow-up.Six patients with recurrent intracranial VADAs after SAC were retreated, with second SAC in three patients, coil embolization, double overlapping stents placement and endovascular occlusion with aneurysm trapping in one patient, respectively. Immediate angiographic outcomes of retreatment were: complete occlusion in three patients, nearly complete occlusion in two patients, and contrast medium retention in dissecting aneurysm in one patient. All cases were technically successful. No complications related to endovascular procedures occurred. Angiographic follow-up was available in all five patients treated with second SAC or double overlapping stents, which was complete occlusion in four patients, obliteration of parent artery in one patient, showing no recurrence at 4-11 months (mean: 8.6 months. Clinical follow-up was performed in all six patients at 11-51 months after initial endovascular treatment and at 9-43 months after retreatment. The mRS of last clinical follow-up was excellent in five patients and mild disability in only one patient.Endovascular retreatment is feasible and effective for recurrent intracranial VADAs after SAC. Individualized strategies of retreatment should be

  20. Re-treatment after full-course radiotherapy: is it a viable option?

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, F.A. [Netherlands Cancer Inst., Amsterdam (Netherlands). Div. of Experimental Therapy

    1999-07-01

    Re-irradiation of previously treated areas may become necessary for recurrent cancer, new primary tumours (common in head and neck cancer patients), or nodal and metastatic disease. Factors that should be taken into account in the decision to re-treat include: (1) Previously treated volume (how much overlap is there with new treatment fields) and dose fractionation schedule; (2) which critical tissues or organs are at risk; (3) how much time has elapsed since first treatment; (4) whether there are any practical alternatives to re-irradiation? Rapidly proliferating tissues generally recover well from the initial radiotherapy and will tolerate re-irradiation to almost full doses. Some slowly proliferating tissues are also capable of partial proliferative and functional recovery, although this takes several months and some residual damage remains. Preclinical data demonstrate that re-irradiation with reduced doses is possible in lung and spinal cord after intervals of 3-6 months. Other slowly proliferating organs, e.g. the kidneys, do not appear to be capable of recovery, even after low, subtolerance doses. The largest clinical experience of re-irradiation is for head and neck cancers. A review of this literature reveals that the most frequent normal tissue complication seen is trismus (lockjaw), which occurs in 16 to 30% of re-treated cases, with lower incidences of soft tissue or bone necrosis and fibrosis. Myelitis is rarely reported, even in the re-treatment situation. In general the highest incidence of local control for the lowest incidence of serious complications is achieved for combinations of external beam and brachytherapy, and for small, well-differentiated, new primary tumours rather than recurrent disease. Re-treatment with total doses <55 Gy gives very poor local control rates. Re-treatment schedules with curative intent require a high re-treatment dose, which is accompanied by an increased risk of normal tissue damage. To minimize serious complications

  1. Evaluating transmission towers potentials during ground faults

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    During ground faults on transmission lines, a number of towers near the fault are likely to acquire high potentials to ground. These tower voltages, if excessive, may present a hazard to humans and animals. This paper presents analytical methods in order to determine the transmission towers potentials during ground faults, for long and short lines. The author developed a global systematic approach to calculate these voltages, which are dependent of a number of factors. Some of the most important factors are: magnitudes of fault currents, fault location with respect to the line terminals, conductor arrangement on the tower and the location of the faulted phase, the ground resistance of the faulted tower, soil resistivity, number, material and size of ground wires. The effects of these factors on the faulted tower voltages have been also examined for different types of power lines.

  2. Contemporary glacier retreat triggers a rapid landslide response, Great Aletsch Glacier, Switzerland

    Science.gov (United States)

    Kos, Andrew; Amann, Florian; Strozzi, Tazio; Delaloye, Reynald; Ruette, Jonas; Springman, Sarah

    2016-12-01

    The destabilization and catastrophic failure of landslides triggered by retreating glaciers is an expected outcome of global climate change and poses a significant threat to inhabitants of glaciated mountain valleys around the globe. Of particular importance are the formation of landslide-dammed lakes, outburst floods, and related sediment entrainment. Based on field observations and remote sensing of a deep-seated landslide, located at the present-day terminus of the Great Aletsch Glacier, we show that the spatiotemporal response of the landslide to glacier retreat is rapid, occurring within a decade. Our observations uniquely capture the critical period of increase in slope deformations, onset of failure, and show that measured displacements at the crown and toe regions of the landslide demonstrate a feedback mechanism between glacier ice reduction and response of the entire landslide body. These observations shed new light on the geomorphological processes of landslide response in paraglacial environments, which were previously understood to occur over significantly longer time periods.

  3. The tenth annual Ion Channel Retreat, Vancouver, Canada, June 25-27, 2012.

    Science.gov (United States)

    Kimlicka, Lynn; Jamieson, Ashley Lauren; Liang, Sophia; Brugger, Saranna; Liang, Dong

    2013-05-01

    Ten years after Aurora Biomed (Vancouver, British Columbia, Canada) hosted the inaugural Ion Channel Retreat, this event is recognized as a leading conference for ion channel researchers. Held annually in Vancouver, this meeting consistently provides an outlet for researchers to share their findings while learning about new concepts, methods, and technologies. Researchers use this forum to discuss and debate a spectrum of topics from ion channel research and technology to drug discovery and safety. The Retreat covered key subjects in the ion channel industry, including ion channels as disease targets, transient receptor protein channels as pain and disease targets, ion channels as pain targets, ion channel structure and function, ion channel screening technologies, cardiac safety and toxicology, and cardiac function and pharmacology.

  4. A pilot study of a weekend retreat intervention for family survivors of homicide.

    Science.gov (United States)

    Tuck, Inez; Baliko, Beverly; Schubert, Christine M; Anderson, Lorraine

    2012-10-01

    Homicide causes negative unintended consequences for family survivors. Family survivors face complicated grief and overwhelming loss with minimal support from others. The authors offered a retreat intervention as a way to ameliorate the effects of the homicidal death for family survivors of homicide. An exploratory longitudinal pilot study examined the feasibility and acceptability of the intervention and explored the impact of the TOZI© Healing intervention on participants' distress symptoms. Eight family members participated in the 2-day retreat and completed surveys at five time intervals over 30 months. Descriptive statistics and correlations were used to analyze the data. Although sample sizes were too small to achieve statistical significance, changes on selected holistic health outcomes, supported by overwhelmingly positive focus group responses to the intervention, affirm the need for further study.

  5. Glacial Retreat and Associated Glacial Lake Hazards in the High Tien Shan

    Science.gov (United States)

    Smith, T. T.

    2013-12-01

    A number of studies have identified glacial retreat throughout the greater Himalayan region over the past few decades, but the Karakorum region remains an anomaly with large stagnating or advancing glaciers. The glacial behavior in the Tien Shan is still unclear, as few studies have investigated mass balances in the region. This study focuses on the highest peaks of the Tien Shan mountain range, in the region of Jengish Chokusu along the Kyrgyzstan-China-Kazakhstan border. In a first step, a 30-year time series of Landsat imagery (n=27) and ASTER imagery (n=10) was developed to track glacial growth and retreat in the region. Using a combination of spectral and topographic information, glacial outlines are automatically delineated. As several important glaciers in the study region contain medium to high levels of debris cover, our algorithm also improves upon current methods of detecting debris-covered glaciers by using topography, distance weighting methods, river networks, and additional spectral data. Linked to glacial retreat are glacial lake outburst floods (GLOFs) that have become increasingly common in High Mountain Asia over the last few decades. As glaciers retreat, their melt water is often trapped by weakly bonded moraines. These moraines have been known to fail due to overtopping caused by surge waves created by avalanches, rockslides, or glacial calving. A suite of studies throughout High Mountain Asia have used remotely-sensed data to monitor the formation and growth of glacial lakes. In a second step of the work, lake-area changes over the past 15 years were tracked monthly and seasonally using dense Landsat/ASTER coverage (n=30) with an automatic procedure based on spectral and topographic information. Previous work has identified GLOFs as a significant process for infrastructural damage in the southern Tien Shan/northern Pamir, as well as in the better studied Himalaya region. Lake identification and quantification of lake-growth rates is a valuable

  6. Building a rheumatology education academy: insights from assessment of needs during a rheumatology division retreat.

    Science.gov (United States)

    Berman, Jessica R; Aizer, Juliet; Bass, Anne R; Cats-Baril, William L; Parrish, Edward J; Robbins, Laura; Salmon, Jane E; Paget, Stephen A

    2012-06-01

    To implement a rheumatology department education retreat to systematically identify and address the key factors necessary to improve medical education in our division in preparation for developing a rheumatology academy. The Hospital for Special Surgery organized a retreat for the Rheumatology Department aimed at (1) providing formal didactics and (2) assessing participants' self-reported skills and interest in education with the goal of directing this information toward formalizing improvement. In a mixed-methods study design, faculty and fellows in the Division of Rheumatology were surveyed online pre- and post-retreat regarding various aspects of the current education program, their teaching abilities, interest and time spent in teaching, divisional resources allocated, and how education is valued. Enthusiasm for teaching was high before and rose further after the retreat. Confidence in abilities was higher than expected before but fell afterward. Many noted that the lack of specific feedback on teaching skills and useful metrics to assess performance prevented the achievement of educational excellence. Most responding felt lack of time, knowledge of how to teach well, and resources prevented them from making greater commitments to educational endeavors and participating fully and effectively in the department's teaching activities. While most rheumatology faculty members want to improve as teachers, they know neither where their educational strengths and weaknesses lie nor where or how to begin to change their teaching abilities. The key elements for an academy would thus be an educational environment that elevates the quality of teaching throughout the division and promotes teaching careers and education research, and raises the importance and quality of teaching to equivalence with clinical care and research.

  7. A week-long meditation retreat decouples behavioral measures of the alerting and executive attention networks.

    Science.gov (United States)

    Elliott, James C; Wallace, B Alan; Giesbrecht, Barry

    2014-01-01

    PREVIOUS STUDIES HAVE EXAMINED THE INFLUENCE OF MEDITATION ON THREE FUNCTIONALLY DIFFERENT COMPONENTS OF ATTENTION: executive control, alerting, and orienting. These studies have consistently found that meditation training improves both executive attention and alerting, but there has not been a consistent and clear effect of meditation training on orienting. In addition, while previous studies have shown that the functional coupling of the alerting and executive networks increases the processing of task irrelevant stimuli, it is unknown if participating in a meditation retreat can decouple these components of attention and lead to improved performance. The current study investigated the influence of a week-long intensive meditation retreat on three components of attention by randomly assigning participants to either pre- or postretreat testing groups. A modified attention network test (ANT) was used. Executive attention was measured as the difference in response time (RT) between congruent and incongruent task irrelevant flankers (conflict effect). Reflexive and volitional orienting were measured by manipulating cue validity and stimulus onset asynchrony (SOA). The coupling of executive attention and alerting was measured by examining flanker interference as a function of the SOA of an alerting cue. The meditation retreat improved task based indices of executive attention, but not reflexive or volitional orienting. There was clear behavioral evidence of coupling between executive attention and alerting in the preretreat group, as the conflict effect peaked when an alerting cue was presented 300 ms before the target. Importantly, there was no increase in the conflict effect for the postretreat group. This is consistent with the notion that the retreat decoupled the executive and alerting networks. These results suggest that previously reported improvements in the executive and alerting networks after meditation training might be mediated by the same underlying

  8. On optimal retreat distance for the equivalent source method-based nearfield acoustical holography.

    Science.gov (United States)

    Bai, Mingsian R; Chen, Ching-Cheng; Lin, Jia-Hong

    2011-03-01

    As a basic form of the equivalent source method (ESM) that is used to nearfield acoustical holography (NAH) problems, discrete monopoles are utilized to represent the sound field of interest. When setting up the virtual source distribution, it is vital to maintain a "retreat distance" between the virtual sources and the actual source surface such that reconstruction would not suffer from singularity problems. However, one cannot increase the distance without bound because of the ill-posedness inherent in the reconstruction process with large distance. In prior research, 1-2 times lattice spacing, or the inter-element distance of microphones, is generally recommended as retreat distance in using the ESM-based NAH. While this rule has shown to yield good results in many cases, the optimal choice is a complicated issue that depends on frequency, geometry of the physical source, content of evanescent waves, distribution of sensors and virtual sources, etc. This paper deals about attaining the best compromise between the reconstruction errors induced by the point source singularity; the reconstruction ill-posedness is an interesting problem in its own right. The paper revisits this issue, with the aid of an optimization algorithm based on the golden section search and parabolic interpolation. Numerical simulations were conducted for a baffled planar piston source and a spherically baffled piston source. The results revealed that the retreat distance appropriate for the ESM ranged from 0.4 to 0.5 times the spacing for the planar piston, while from 0.8 to 1.7 times average spacing for the spherical piston. Experiments carried out for a vibrating aluminum plate also revealed that the retreat distance with 0.5 times the spacing yielded better reconstructed velocity than those with 1/20 and 1 times the spacing.

  9. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming.

    Science.gov (United States)

    Jomelli, Vincent; Khodri, Myriam; Favier, Vincent; Brunstein, Daniel; Ledru, Marie-Pierre; Wagnon, Patrick; Blard, Pierre-Henri; Sicart, Jean-Emmanuel; Braucher, Régis; Grancher, Delphine; Bourlès, Didier Louis; Braconnot, Pascale; Vuille, Mathias

    2011-06-08

    The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8 ± 0.9 to 8.5 ± 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 ± 0.8 °C cooler at 11 kyr ago and remained -2.1 ± 0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics.

  10. Calving Theory and the Thinning, Retreat, and Disarticulation of Bear Glacier, Alaska

    Science.gov (United States)

    Molnia, B. F.

    2007-12-01

    Bear Glacier, with an area of ~225 km2, is a 25-km long valley glacier located in the southern Kenai Mountains. When first mapped in 1909, it had a piedmont lobe with an area of >30 km2. By the mid- 1980s, the terminus had retreated from 1-3 km, thinned by >150 m, and was actively calving small icebergs into an ice-marginal lake. Through the end of the 20th century, the piedmont lobe continued to thin and narrow. Active calving decreased and then ceased as the thickness of the thinning glacier approached Tnb, the thickness of neutral buoyancy (the floatation thickness). As thinning continued, much of the terminus began to float. Passive calving, characterized by the release of large tabular icebergs from Bear's low gradient, low elevation terminus, became the dominant retreat process. Between 2000 and 2007, part of the terminus retreated about 3.6 km. Now, 0.5 km-long icebergs frequently separate from Bear's western terminus. An August 2006 bathymetric survey identified many locations with depths >75 m in Bear Glacier's ice-marginal lake. Calving theory can be used to explain much of Bear's observed behavior. Current calving theory suggests that active calving is initiated when a glacier terminus thins to a critical thickness, (i.e. Tnb plus an additional but limited thickness of ice such as 50 m [Tnb+ 50 m]). The thinning of Bear Glacier during much of the 20th century resulted in it approaching this thickness. In a freshwater lake with a depth of ~75 m, active calving would be initiated when Tnb + 50 m was about 120 m, continuing as the glacier thinned to icebergs began to be produced through passive calving (disarticulation), generally separating along former crevasse scars and fractures. These are the condition that resulted in the catastrophic retreat that characterizes Bear Glacier's 21st century behavior.

  11. Panretinal photocoagulation versus intravitreal injection retreatment pain in high-risk proliferative diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Célia Regina Farias de Araújo Lucena

    2013-02-01

    Full Text Available PURPOSE: To compare pain related to intravitreal injection and panretinal photocoagulation in the management of patients with high-risk proliferative diabetic retinopathy. METHODS: Prospective study including patients with high-risk proliferative diabetic retinopathy and no prior laser treatment randomly assigned to receive panretinal photocoagulation (PRP group or panretinal photocoagulation plus intravitreal ranibizumab (PRPplus group. In all patients, panretinal photocoagulation was administered in two sessions (weeks 0 and 2, and intravitreal ranibizumab was administered at the end of the first laser session in the PRPplus group. Retreatment was performed at weeks 16 and 32 if active new vessels were detected at fluorescein angiography. Patients in the PRPplus group received intravitreal ranibizumab and patients in the PRP group received 500-µm additional spots per quadrant of active new vessels. After the end of retreatment, a 100-degree Visual Analog Scale was used for pain score estimation. The patient was asked about the intensity of pain during the whole procedure (retinal photocoagulation session or intravitreal ranibizumab injection. Statistics for pain score comparison were performed using a non-parametric test (Wilcoxon rank sums. RESULTS: Seventeen patients from PRPplus and 14 from PRP group were evaluated for pain scores. There were no significant differences between both groups regarding gender, glycosylated hemoglobin and disease duration. Mean intravitreal injection pain (±SEM was 4.7 ± 2.1 and was significantly lower (p<0.0001 than mean panretinal photocoagulation pain (60.8 ± 7.8. Twelve out of 17 patients from the PRPplus group referred intensity pain score of zero, while the minimal score found in PRP group was found in one patient with 10.5. CONCLUSION: In patients with high-risk proliferative diabetic retinopathy who needed retreatment for persistent new vessels, there was more comfort for the patient when retreatment

  12. Infliximab as the First Retreatment in Patients with Kawasaki Disease Resistant to Initial Intravenous Immunoglobulin.

    Science.gov (United States)

    Youn, Youngmin; Kim, Jisoo; Hong, Young Mi; Sohn, Sejung

    2016-04-01

    Forty-three patients with Kawasaki disease who were resistant to initial intravenous immunoglobulin (IVIG) were randomized to receive either a second dose of IVIG (n = 32) or an infliximab (n = 11). With IVIG retreatment 21 patients (65.6%) responded, and with infliximab 10 patients (90.9%) responded. The infliximab group had shorter duration of fever and fewer days of hospitalization. Coronary artery outcomes and adverse events were similar.

  13. The Tenth Annual Ion Channel Retreat, Vancouver, Canada, June 25–27, 2012

    OpenAIRE

    Kimlicka, Lynn; Jamieson, Ashley Lauren; Liang, Sophia; Brugger, Saranna; Liang, Dong

    2013-01-01

    Ten years after Aurora Biomed (Vancouver, British Columbia, Canada) hosted the inaugural Ion Channel Retreat, this event is recognized as a leading conference for ion channel researchers. Held annually in Vancouver, this meeting consistently provides an outlet for researchers to share their findings while learning about new concepts, methods, and technologies. Researchers use this forum to discuss and debate a spectrum of topics from ion channel research and technology to drug discovery and s...

  14. A complex deglacial retreat history of the Anvers Island Trough paleo-ice stream

    Science.gov (United States)

    Shevenell, A.; Ishman, S. E.; Domack, E. W.; Leventer, A.; Rosenheim, B. E.; Vadman, K. J.

    2015-12-01

    Marine-terminating ice regulates the mass balance and stability of Antarctica's ice sheets and, ultimately, global sea level. However, predictions of future ice sheet response to climate change are limited by short observational time-series and the complexity of associated forcings and feedbacks. Here, we present new chronologic and multiproxy data from 7 marine sediment records from the outer to inner shelf down the axis of the Anvers Island Trough and into Palmer Deep that better constrain the timing and rate of ice retreat and improve understanding of the mechanisms driving deglaciation of this hypothesized paleo-ice stream. The retreat chronology is based on 16 CaCO3 (foraminifer and mollusk) and 45 ramped pyrolysis (acid-insoluble organic matter) AMS 14C dates. Radiocarbon dates from the laminated diatom ooze and mud facies immediately above the glacial diamicton indicate that deglaciation of the mid-Anvers Island Trough post-dated the Palmer Deep deglaciation by ~2000 uncorrected 14C years and that collapse of the mid-shelf system was rapid, if not instantaneous. The laminated facies, present throughout the suite of cores, is consistent with the calving bay reentrant model for deglaciation. However, this facies is limited (~15 couplets) on the mid-shelf and expanded (~127 couplets) on the inner-shelf, suggesting regional differences in calving bay duration. Planktic and benthic foraminifer isotopes, together with foraminifer and diatom assemblages, and biogeochemical data provide evidence for the presence of warmer nutrient-rich modified Circumpolar Deep Water throughout the Anvers Island Trough during deglaciation. The observed retreat complexity may relate to a hypothesized mid-shelf ice-dome system and requires additional geological and geophysical data to understand ice retreat patterns south and west of Palmer Deep. Such data will provide important new constraints for ice sheet models.

  15. The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss

    OpenAIRE

    Notz, Dirk

    2009-01-01

    We discuss the existence of cryospheric “tipping points” in the Earth's climate system. Such critical thresholds have been suggested to exist for the disappearance of Arctic sea ice and the retreat of ice sheets: Once these ice masses have shrunk below an anticipated critical extent, the ice–albedo feedback might lead to the irreversible and unstoppable loss of the remaining ice. We here give an overview of our current understanding of such threshold behavior. By using conceptual arguments, w...

  16. Plasticity of visual attention in Isha yoga meditation practitioners before and after a 3-month retreat

    Directory of Open Access Journals (Sweden)

    Claire eBraboszcz

    2013-12-01

    Full Text Available Meditation has lately received considerable interest from cognitive neuroscience. Studies suggest that daily meditation leads to long lasting attentional and neuronal plasticity. We present changes related to the attentional systems before and after a 3 month intensive meditation retreat. We used 3 behavioral psychophysical tests - a Stroop task, an attentional blink task, and a global-local letter task - to assess the effect of Isha yoga meditation on attentional resource allocation. 82 Isha yoga practitioners were tested at the beginning and at the end of the retreat. Our results showed an increase in correct responses specific to incongruent stimuli in the Stroop task. Congruently, a positive correlation between previous meditation experience and accuracy to incongruent Stroop stimuli was also observed at baseline. We also observed a reduction of the attentional blink. Unexpectedly, a negative correlation between previous meditation experience and attentional blink performance at baseline was observed. Regarding spatial attention orientation as assessed using the global-local letter task, participants showed a bias toward local processing. Only slight differences in performance were found pre- vs. post- meditation retreat. Previous meditation experience influenced the Stroop and attentional blink tasks in opposite directions – for the Stroop task congruent with the improvements seen after the retreat whereas for the attentional blink previous experience correlated negatively with performance. Biasing towards the local stimuli in the global-local task and negative correlation of previous meditation experience with attentional blink performance is consistent with Isha practices being more focused-attention practices. Given the relatively small effect sizes and the absence of a control group, our results do not allow clear support nor rejection of the hypothesis of meditation-driven neuronal plasticity in the attentional system for Isha yoga

  17. Satellite Observations of Glacier Advances and Retreat in the Western Karakoram

    Science.gov (United States)

    Haritashya, U. K.; Bishop, M. P.; Shroder, J. F.; Bulley, H. N.

    2007-12-01

    Debris-covered alpine glaciers around the world have been retreating and downwasting. This suggests glacier response to atmospheric warming. Recent studies in the eastern Himalaya have shown systematic retreat for many glaciers. In the western Himalaya, however, systematic and quantitative data are not yet available to determine glacier sensitivity and mass balance trend. Given the paucity of bench-mark glaciers in the Himalaya, remote-sensing-based studies are required to obtain baseline information and produce estimates of advance and retreat rates. Consequently, our objectives were to assess glacier fluctuations in the western Karakoram of Pakistan as a part of the Global Land Ice Measurements from Space (GLIMS) project. Specifically, we used multi- temporal satellite data (ASTER 09/13/2004, Landsat TM 10/15/1992, and Landsat MSS 07/15/1992) to quantitatively assess terminus fluctuations. Results indicate that more than 50 percent of the sampled large and large-medium sized glaciers are advancing, and/or exhibit similar terminus positions to past positions. For example, Bualtar Glacier is advancing at the rate of 11 m/yr. On the other hand, most of the small-medium to small glaciers, such as Mani Glacier are retreating (15 m/yr). Some of these glaciers have also shown strong downwasting characteristics in the form of increased frequency and size of supraglacial lakes. Collectively, our results indicate that these glaciers may be responding differently to the current climatic conditions than in the eastern Himalaya (east of the Karakoram) and Wakhan Pamir region (northwest of the Karakoram). These quantitative results from remote-sensing studies also indicate that glacier fluctuations in this region are spatially and temporally complex. These complexities may be governed by multi-scaled topographic effects, as well as by variations in winter precipitation and decreases in summer temperature from increased cloudiness, as suggested by others.

  18. Experimental observations on the retreat of non-cohesive river banks

    Science.gov (United States)

    Solari, L.; Nardi, L.; Rinaldi, M.

    2009-12-01

    The topic of bank retreat is of particular relevance in the hydro-morphodynamic models devoted to study the planform evolution of rivers. This notwithstanding, in many models bank retreat is evaluated through over-simplified algorithms based, for instance, on the knowledge of the near bank flow velocity and some erodibility coefficient which does not have an explicit physical meaning. In the literature, the majority of studies on the modelling of bank processes are about cohesive banks composed by fine sediments; the retreat of these type of banks has been related to the stability and mass wasting processes through algorithms originally developed in the geotechnical field. In gravel-bed rivers, banks are often composite with a basal layer of gravel and an upper cohesive layer, or, sometime, completely composed by granular, relatively coarse sediments (gravel and cobbles). The mechanisms of bank retreat in relatively coarse riverbanks (mainly composed by gravel) represent an area that needs further investigation, as numerous physical mechanisms are still not understood. This research aims at gaining a better comprehension of the basic processes occurring in relatively coarse bank sediments; in particular, it focuses on the mass instability mechanisms due to the oscillations of free surface water level. The fluvial erosion of the streambank due to the boundary shear stresses is not taken into account. A physical model of a bank composed by granular relatively coarse sediments has been reproduced in a static tank. The main characteristics of the bank; such as geometry, sediment distribution and degree of packing, were set on the basis of the field observations of the riverbanks in the Cecina River (Tuscany). A first set of experiments simulating the behavior of the bank during a hydrograph has been carried out. Several sensors inserted into the bank allow monitoring the seepage flow and pore water pressures. Preliminary results are here reported, with a discussion of

  19. Title: Climate-glacier Relationship of Retreating Alaskan Glaciers Author: Elliott Mazur and Umesh K. Haritashya

    Science.gov (United States)

    Mazur, E. M.

    2012-12-01

    Portage, Whittier, Eklutna, as well as many other well-known "tourism glaciers" in the vicinity of Anchorage, Alaska are known to have retreated in the past 20 years. This begs the question, "what of the other lesser-known glaciers? Do they follow the same patterns and minimal glacier models?" Glaciers such as Byron, Leonard, Matanuska, Raven and Spencer may fit a minimal model. Information on Byron and Leonard is sparse, as both have become hanging glaciers. Other glaciers, such as Raven, are small enough to be deemed insignificant, yet may have information to give. Consequently our objective is to study five Alaskan glaciers and determine wide-ranging variability to changing regional climate. To do this we obtained field geo-location data and characterized glaciers based on the satellite imagery and climate reevaluation. Our result shows that glaciers are retreating and thinning irrespective of their aspects, location and altitudinal variability. Moreover, our presentation establishes the strong climate-glacier relationship and defines retreating snowline patterns over the last few decades.

  20. Debate: single-fraction treatment should be standard in the retreatment of uncomplicated bone metastases.

    Science.gov (United States)

    Tsang, Derek S; Yau, Vivian; Raziee, Hamid; Niglas, Mark; Soliman, Hany; Chow, Edward; Tsao, May

    2015-10-01

    There is controversy surrounding the optimal radiotherapy dose-fractionation for retreatment of painful bone metastases. Two commonly used regimens are 8 Gy in a single-fraction or 20 Gy in five or eight fractions. Randomized evidence, including the NCIC SC.20 randomized clinical trial, has failed to standardize clinical practice. Practitioners who use single-fraction regimens cite patient convenience, fewer acute adverse effects, and better cost-effectiveness. Practitioners who prefer multiple fractions raise questions about the interpretation of data that justifies single-fraction treatment, and the possibility that single-fraction treatment may provide inferior pain relief. Given this clinical controversy, should single-fraction irradiation be standard in retreatment of uncomplicated bone metastases? In this article, two teams debate both sides of the argument with commentary to summarize the relevant issues. The conclusion from the debate is that the "standard" treatment should be individualized to the patient with shared-decision making between the oncologist, patient and family members. In a cancer patient with poor performance status and short life expectancy, single-fraction repeat radiotherapy may be preferred; in a patient with a prolonged disease course, perhaps multiple fraction retreatments would be preferred. The choice between different fractionation schemes depends on an assessment of individual patient factors, tumour factors and unique patient circumstances.

  1. Plasticity of visual attention in Isha yoga meditation practitioners before and after a 3-month retreat.

    Science.gov (United States)

    Braboszcz, Claire; Cahn, B Rael; Balakrishnan, Bhavani; Maturi, Raj K; Grandchamp, Romain; Delorme, Arnaud

    2013-01-01

    Meditation has lately received considerable interest from cognitive neuroscience. Studies suggest that daily meditation leads to long lasting attentional and neuronal plasticity. We present changes related to the attentional systems before and after a 3 month intensive meditation retreat. We used three behavioral psychophysical tests - a Stroop task, an attentional blink task, and a global-local letter task-to assess the effect of Isha yoga meditation on attentional resource allocation. 82 Isha yoga practitioners were tested at the beginning and at the end of the retreat. Our results showed an increase in correct responses specific to incongruent stimuli in the Stroop task. Congruently, a positive correlation between previous meditation experience and accuracy to incongruent Stroop stimuli was also observed at baseline. We also observed a reduction of the attentional blink. Unexpectedly, a negative correlation between previous meditation experience and attentional blink performance at baseline was observed. Regarding spatial attention orientation as assessed using the global-local letter task, participants showed a bias toward local processing. Only slight differences in performance were found pre- vs. post- meditation retreat. Biasing toward the local stimuli in the global-local task and negative correlation of previous meditation experience with attentional blink performance is consistent with Isha practices being focused-attention practices. Given the relatively small effect sizes and the absence of a control group, our results do not allow clear support nor rejection of the hypothesis of meditation-driven neuronal plasticity in the attentional system for Isha yoga practice.

  2. Skin-deep diagnosis: affective bias and zebra retreat complicating the diagnosis of systemic sclerosis.

    Science.gov (United States)

    Miller, Chad S

    2013-01-01

    Nearly half of medical errors can be attributed to an error of clinical reasoning or decision making. It is estimated that the correct diagnosis is missed or delayed in between 5% and 14% of acute hospital admissions. Through understanding why and how physicians make these errors, it is hoped that strategies can be developed to decrease the number of these errors. In the present case, a patient presented with dyspnea, gastrointestinal symptoms and weight loss; the diagnosis was initially missed when the treating physicians took mental short cuts and used heuristics as in this case. Heuristics have an inherent bias that can lead to faulty reasoning or conclusions, especially in complex or difficult cases. Affective bias, which is the overinvolvement of emotion in clinical decision making, limited the available information for diagnosis because of the hesitancy to acquire a full history and perform a complete physical examination in this patient. Zebra retreat, another type of bias, is when a rare diagnosis figures prominently on the differential diagnosis but the physician retreats for various reasons. Zebra retreat also factored in the delayed diagnosis. Through the description of these clinical reasoning errors in an actual case, it is hoped that future errors can be prevented or inspiration for additional research in this area will develop.

  3. Ecosystem response to a temporary sea ice retreat in the Bering Sea: Winter 2009

    Science.gov (United States)

    Miksis-Olds, Jennifer L.; Stabeno, Phyllis J.; Napp, Jeffery M.; Pinchuk, Alexei I.; Nystuen, Jeffrey A.; Warren, Joseph D.; Denes, Samuel L.

    2013-04-01

    Adding acoustic systems onto ocean moorings and observatories provides additional data to more fully document ecosystem responses to environmental perturbations. A passive acoustic recorder and three-frequency echosounder system were integrated into a biophysical mooring on the central eastern Bering Sea continental shelf. An unexpected, transient, mid-winter retreat of the seasonal sea ice was observed over the mooring for a 2-week period in March 2009. Interpretation of the passive acoustic data provided information about sea ice conditions and included the detection and identification of vocalizing marine mammals, while the acoustic backscatter provided information on relative zooplankton and fish abundance before, during, and after the retreat. Hydrographic data confirmed the acoustic signal was associated with changing surface ice conditions, and the combined information from the biophysical mooring sensors revealed changes in winter trophic level dynamics during the retreat, which would have otherwise been undetected by traditional ship-based observations. Changes in the acoustic environment, zooplankton dynamics, and acoustic detection of marine mammals were observed amidst a physically stable and uniform water column with no indication of a phytoplankton bloom. These data demonstrate the value of acoustic technologies to monitor changing ecosystems dynamics in remote and hazardous locations.

  4. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    Science.gov (United States)

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP.

  5. The recent retreat of Mexican glaciers on Citlaltépetl Volcano detected using ASTER data

    Science.gov (United States)

    Cortés-Ramos, J.; Delgado-Granados, H.

    2012-08-01

    Satellite imagery and net radiation data collected between 2001 and 2007 for Citlaltépetl Volcano confirm the dramatic shrinkage of Glaciar Norte and the elimination of Jamapa and Chichimeco glacier tongues. The Glaciar Norte rapidly retreated between 2001 and 2002 while for 2007 this retreat decreases considerably. Jamapa and Chichimeco tongues disappeared by 2001 as compared to the geometry shown for 1958. The Glaciar Norte lost about 72% of its surface area between 1958 and 2007. Recently, the ice loss appears to be accelerating as evidenced by the 33% areal loss in just 6 yr between 2001 and 2007. At this shrinkage rate the glaciers would be gone from the volcano by the year 2020, which is decades earlier than previously estimated. The net radiation from ASTER images and the energy fluxes calculated via the meteorological data at the glacial surface show the close relationship between glacial shrinkage and surface energy balance. The magnitude of changes in the net radiation balance allows improved understanding of glacial retreat in Mexico.

  6. Prevalence of multidrug resistance among retreatment pulmonary tuberculosis cases in a tertiary care hospital, Hyderabad, India

    Directory of Open Access Journals (Sweden)

    Subhakar Kandi

    2013-01-01

    Full Text Available Background: India is one of the high tuberculosis (TB burden countries in the world. India ranks second in harboring multi drug resistant (MDR-TB cases. About 50,000 of MDR cases are recorded in retreatment pulmonary TB cases. This study was conducted in a tertiary care facility (Government General and Chest Hospital in Hyderabad, India. Objectives: Toassess: Proportion of the TB patients having MDR-TB at the initiation of retreatment regimen; the prevalence of isoniazid (INH resistance in this geographical area. Materials and Methods: An analytical, observational, prospective cohort study of patients attending the out-patient department from December 2010 to March 2011. Results: Sputum samples from 100 patients were subjected to acid fast bacilli (AFB culture and drug sensitivity testing. Of these, 28 (28% were MDR-TB, 42 (42% were non-MDR-TB and 39% being INH resistance. Conclusions: In conclusion, one third of the retreatment pulmonary TB cases attending a tertiary care institute for TB will be MDR-TB at the initiation of treatment and there is a need to include ethambutol in the continuation phase of new TB case treatment in view of high INH resistance.

  7. Diachronous retreat of the Greenland ice sheet during the last deglaciation

    Science.gov (United States)

    Sinclair, G.; Carlson, A. E.; Mix, A. C.; Lecavalier, B. S.; Milne, G.; Mathias, A.; Buizert, C.; DeConto, R.

    2016-08-01

    The last deglaciation is the most recent interval of large-scale climate change that drove the Greenland ice sheet from continental shelf to within its present extent. Here, we use a database of 645 published 10Be ages from Greenland to document the spatial and temporal patterns of retreat of the Greenland ice sheet during the last deglaciation. Following initial retreat of its marine margins, most land-based deglaciation occurred in Greenland following the end of the Younger Dryas cold period (12.9-11.7 ka). However, deglaciation in east Greenland peaked significantly earlier (13.0-11.5 ka) than that in south Greenland (11.0-10 ka) or west Greenland (10.5-7.0 ka). The terrestrial deglaciation of east and south Greenland coincide with adjacent ocean warming. 14C ages and a recent ice-sheet model reconstruction do not capture this progression of terrestrial deglacial ages from east to west Greenland, showing deglaciation occurring later than observed in 10Be ages. This model-data misfit likely reflects the absence of realistic ice-ocean interactions. We suggest that oceanic changes may have played an important role in driving the spatial-temporal ice-retreat pattern evident in the 10Be data.

  8. Micro-CT Evaluation of Root Filling Removal after Three Stages of Retreatment Procedure.

    Science.gov (United States)

    Da Rosa, Ricardo Abreu; Santini, Manuela Favarin; Cavenago, Bruno Cavalini; Pereira, Jefferson Ricardo; Duarte, Marco Antônio Húngaro; Só, Marcus Vinícius Reis

    2015-01-01

    The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunn's post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.

  9. Flotation and retreat of a lake-calving terminus, Mendenhall Glacier, southeast Alaska, USA

    Science.gov (United States)

    Boyce, Eleanor S.; Motyka, Roman J.; Truffer, Martin

    Mendenhall Glacier is a lake-calving glacier in southeastern Alaska, USA, that is experiencing substantial thinning and increasingly rapid recession. Long-term mass wastage linked to climatic trends is responsible for thinning of the lower glacier and leaving the terminus vulnerable to buoyancy-driven calving and accelerated retreat. Bedrock topography has played a major role in stabilizing the terminus between periods of rapid calving and retreat. Lake-terminating glaciers form a population distinct from both tidewater glaciers and polar ice tongues, with some similarities to both groups. Lacustrine termini experience fewer perturbations (e.g. tidal flexure, high subaqueous melt rates) and are therefore inherently more stable than tidewater termini. At Mendenhall, rapid thinning and simultaneous retreat into a deeper basin led to flotation conditions along approximately 50% of the calving front. This unstable terminus geometry lasted for approximately 2 years and culminated in large-scale calving and terminus collapse during summer 2004. Buoyancy-driven calving events and terminus break-up can result from small, rapidly applied perturbations in lake level.

  10. Glacier Retreat in the Cordillera Quimza Cruz (Tres Cruces), Bolivia from 1975 to present

    Science.gov (United States)

    Klein, A. G.; Kincaid, J. L.; Brooks, R. M.

    2008-12-01

    The glaciers in the Cordillera Quimza Cruz (Tres Cruces) and two smaller Bolivian massifs represent the southernmost tropical glaciers found along the eastern margin of the Andes. Their marginal location makes them of particular interest. The extent of glaciers in the mid 1970s was determined though digitization of the published glacier inventory of Bolivia. In 1975, extent of glaciers in the Tres Cruces region was approximately 55.4 square kilometers. More recent extents were determined from Landsat and ASTER satellite images. Cloud-free Landsat images from 1986, 1992 and 2000 were georegistered and surface reflectances were computed. Normalized Difference Snow Index (NDSI) images were then computed and thresholded to create binary maps of snow- and glacier-covered pixels. From 1975 through 2000, the Tres Cruces Region lost a significant amount of its glacier area. Of the area identified as being glacier covered in 1975 only 27.4 square kilometers (49%) were identified as containing snow and ice in Landsat images from 2000. The glacier retreat time series is being updated as part of an ongoing undergraduate research program. More recent retreat mapped from multiple ASTER images from 2000-2006 indicates that glacier recession is continuing. Changes in glacier hypsometries indicate that much of the areal loss has occurred at lower altitudes. The influence of aspect on glacier retreat is the next area of investigation.

  11. High space-time resolution analysis of ice motion at a rapidly retreating tidewater glacier (Invited)

    Science.gov (United States)

    Oneel, S.; Joughin, I. R.; March, R. S.; Burgess, E. W.; Welty, E.; Pfeffer, W. T.; Larsen, C. F.

    2013-12-01

    Rapid changes to rates of sea level rise are forced in large part by tidewater glacier dynamics. Alaska's Columbia Glacier is an iconic example; in recent years, calving losses account for roughly 20% of the net mass loss from the entire Alaska region. In turn, the Alaska region accounts for ~20% of global new-water sea-level rise. To better understand the mechanics of rapid tidewater glacier mass loss, we present and analyze surface elevation and velocity data acquired at high time resolution since fall 2011. Strong seasonality in flow speed exists, with more than a doubling of near-terminus speed occurring between summer and winter. The imagery provides unprecedented spatial coverage, demonstrating spatial coherence in flow variability across most, but not all, tributaries. Preliminary calculations of ice flux also show strong seasonality, with variable year-to-year timing of peak discharge. Compared to previous estimates, the average flux in this most recent interval is reduced by ~30-40%. An additional overdeepening is located upstream from the present-day terminus, indicating another episode of increased flux is possible. However, total glacier volume has been reduced by ~50% during the retreat, and peak discharge from Columbia has likely already occurred. Our analysis suggests that, as the Columbia Glacier retreat comes to a conclusion, rates of mass loss from the Alaska region will decrease in the near-future, unless another tidewater glacier enters rapid retreat.

  12. Cost-effectiveness of retreatment with varenicline after failure with or relapse after initial treatment for smoking cessation

    Directory of Open Access Journals (Sweden)

    Lieven Annemans

    2015-01-01

    Conclusion: This analysis suggests that in the long term, varenicline retreatment is a dominant intervention, meaning both greater health gains and greater costs saved, over other possible interventions and therefore should be considered as a standard option.

  13. Call for papers: SAJHE special issue 'Re-imagining writing retreats for academic staff in higher education'

    Directory of Open Access Journals (Sweden)

    Guest Editors

    2016-06-01

    Full Text Available Call for papers for an upcoming special issue of the South African Journal of Higher Education (SAJHE in 2016: ‘Re-imagining writing retreats for academic staff in higher education’.

  14. Retarded deglaciation of north-Spitsbergen fjords during the last glacial - an example of bathymetric controls on the dynamics of retreating glaciers

    Science.gov (United States)

    Forwick, M.; Vorren, T. O.; Hass, H.; Vogt, C. M.

    2012-12-01

    North and west Spitsbergen fjords acted as pathways for fast-flowing ice streams during the last glacial (e.g. Ottesen et al., 2005). The deglaciation of west Spitsbergen fjords occurred stepwise and the ice retreat terminated around 11,200 cal. years BP (calendar years before the present; e.g. Forwick & Vorren, 2009, 2011, and references therein; Baeten et al., 2010). However, the deglaciation dynamics and chronology of north Spitsbergen fjords still remain poorly understood. We present swath-bathymetry, high-resolution seismic data and two sediment cores from the approx. 110 km long, N-S oriented Wijdefjorden-Austfjorden fjord system, the largest fjord system on northern Spitsbergen. The data indicate that - as in the fjords on west Spitsbergen - multiple halts and/or readvances interrupted the retreat of the ice front during the final phase of the last glacial. However, even though the study area and several west Spitsbergen fjords are fed by the same glacier source (the ice field Lomonosovfonna), the final deglaciation of Wijdefjorden-Austfjorden took place after 9300 cal. years BP, i.e. at least approx. 2000 years later than in the west. We assume that the retarded deglaciation in the north is mainly related to the fjord bathymetry, i.e. a more than 35 km wide and up to 60 m high area in the central parts of the study area (approx. 45 km beyond the present fjord head) that acted as pinning point for the grounded glacier. Multiple, relatively large and partly stacked moraine ridges and sediment wedges are suggested to reflected that the ice front retreated slowly across this shallow area and that repeated readvances interrupted this retreat. The absence of larger sediment wedges in the deeper parts between the shallow area and the fjord head may indicate that the final retreat occurred relatively rapid. References: Baeten, N.J., Forwick, M., Vogt, C. & Vorren, T.O., 2010. Late Weichselian and Holocene sedimentary environments and glacial activity in

  15. 'Grounded' Politics

    DEFF Research Database (Denmark)

    Schmidt, Garbi

    2012-01-01

    play within one particular neighbourhood: Nørrebro in the Danish capital, Copenhagen. The article introduces the concept of grounded politics to analyse how groups of Muslim immigrants in Nørrebro use the space, relationships and history of the neighbourhood for identity political statements....... The article further describes how national political debates over the Muslim presence in Denmark affect identity political manifestations within Nørrebro. By using Duncan Bell’s concept of mythscape (Bell, 2003), the article shows how some political actors idealize Nørrebro’s past to contest the present...

  16. Cavity lining after excavating caries lesions

    DEFF Research Database (Denmark)

    Schwendicke, Falk; Göstemeyer, Gerd; Gluud, Christian

    2015-01-01

    OBJECTIVES: After removal of dentin caries lesions, cavity lining has been advocated. Non-clinical data support this approach, but clinical data are sparse and ambiguous. We aimed at evaluating the benefits and harms of cavity lining using meta-analysis and Trial Sequential Analysis. DATA: We...... included randomized clinical trials comparing restorations without versus with cavity lining for treating primary caries lesions. Only trials reporting failure (defined as need to re-retreat) after ≥1 year follow-up were included. Trial selection, data extraction, and risk of bias assessment were conducted....... STUDY SELECTION: From 128 studies, three randomized trials (89/130 patients or teeth), all treating primary teeth, were included. The trials had high risk of bias. All trials compared no lining versus calcium hydroxide lining after selective caries removal followed by adhesive restoration. Follow...

  17. Navigated macular laser decreases retreatment rate for diabetic macular edema: a comparison with conventional macular laser

    Directory of Open Access Journals (Sweden)

    Neubauer AS

    2013-01-01

    Full Text Available Aljoscha S Neubauer,1,* Julian Langer,1,* Raffael Liegl,1 Christos Haritoglou,1 Armin Wolf,1 Igor Kozak,2 Florian Seidensticker,1 Michael Ulbig,1 William R Freeman,2 Anselm Kampik,1 Marcus Kernt,1 1Ludwig-Maximilians University, Department of Ophthalmology, Munich, Germany; 2Jacobs Retina Center, University of California San Diego, La Jolla, CA, USA*These authors contributed equally to this workBackground: The purpose of this study was to evaluate and compare clinical outcomes and retreatment rates using navigated macular laser versus conventional laser for the treatment of diabetic macular edema (DME.Methods: In this prospective, interventional pilot study, 46 eyes from 46 consecutive patients with DME were allocated to receive macular laser photocoagulation using navigated laser. Best corrected visual acuity and retreatment rate were evaluated for up to 12 months after treatment. The control group was drawn based on chart review of 119 patients treated by conventional laser at the same institutions during the same time period. Propensity score matching was performed with Stata, based on the nearest-neighbor method.Results: Propensity score matching for age, gender, baseline visual acuity, and number of laser spots yielded 28 matched patients for the control group. Visual acuity after navigated macular laser improved from a mean 0.48 ± 0.37 logMAR by a mean +2.9 letters after 3 months, while the control group showed a mean −4.0 letters (P = 0.03. After 6 months, navigated laser maintained a mean visual gain of +3.3 letters, and the conventional laser group showed a slower mean increase to +1.9 letters versus baseline. Using Kaplan-Meier analysis, the laser retreatment rate showed separation of the survival curves after 2 months, with fewer retreatments in the navigated group than in the conventional laser group during the first 8 months (18% versus 31%, respectively, P = 0.02.Conclusion: The short-term results of this pilot study suggest

  18. Near Realtime Monitoring of Tidewater Glacier Advance and Retreat: Hubbard Glacier, Southeast Alaska

    Science.gov (United States)

    Finnegan, D. C.; Lawson, D. E.; Hanlon, G.; Kalli, G.

    2007-12-01

    Tidewater glaciers advance and retreat seasonally as part of the well-documented tidewater glacier cycle. Quantitative factors that influence tidewater glacier activity are often difficult to capture. The accurate collection of such data is a key to better understanding this cycle. In this paper, we describe the results of current research at Hubbard Glacier to quantify realtime glacier terminus activity using high-resolution ranging measurements and local meteorologic conditions. Hubbard Glacier is the largest non-polar tidewater glacier in the world. It encompasses an area of 3500 sq km and flows 120 km from the flanks of Mt Logan (5959 m) in the Wrangell St. Elias Mountains (Canada) to sea level where its terminus widens to ~11.5 km. In contrast to most glaciers in Southeast Alaska, Hubbard Glacier continues to advance and thicken and is predicted to continue for the foreseeable future. Our data provide unique, high-resolution (4 times daily) measurements of ice margin motion along a section of the terminus near Gilbert Point. Gilbert Point is the location of past ice dams formed by Hubbard Glacier (1986, 2002) both of which failed and generated massive outburst floods. This location is critical to understanding the potential for future ice dam formation by Hubbard Glacier. Preliminary results of monitoring since late 2006 indicate variable rates in ice motion within periods of overall advance and retreat. A seasonal advance of the glacier occurred from March to mid-June 2007, advancing 280 m in 98 days at an average of 2.85 m/day, but with daily average rates occasionally as high as 10 m/day. A period of retreat began in mid-June with a large calving event that removed 60 m of ice from the terminus in less than a day. This seasonal retreat has continued with retreat rates varying from 1.11 m/day in the first 45 days to 2.39 m/day between August 1st and 30th, 2007.

  19. Observations of historical sea cliff retreat rates exceed long-term estimates derived from cosmogenic 10Be

    Science.gov (United States)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.; Anderson, Robert S.

    2015-04-01

    Historical observation of coastal retreat are limited to relatively short timescales (change may be accelerated in the face of anticipated stormier climates and rising sea level, yet there is little knowledge of rates of coastal change prior to the relatively brief historical records. In order to make predictions about potential future coastal change it is important to establish baseline conditions averaged over longer time periods. Here we present analysis of sea cliff retreat throughout the Holocene averaged for chalk cliffs in south-east England using cosmogenic isotopes. We determine long-term rates of sea cliff erosion from 10Be measured from in-situ flint samples collected from three transects across coastal platforms in East Sussex. A numerical model of 10Be accumulation on an evolving coastal profile allows estimation of cliff retreat rate during the Holocene. The model accounts for variation in 10Be accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. We find that cliff retreat rates during the Holocene were significantly slower (2-6 cm yr-1) than those derived from recent historical observations (15-25 cm yr-1). Modelled accumulation of 10Be requires retreat rates that increase rapidly in recent times, potentially reflecting human modification of the coastal sediment budget through construction of sea defences, flood defenses and aggregate extraction. Therefore knowledge of past human activity at the coastline may be important in anticipating future rates of coastal retreat.

  20. Deglacial to Holocene history of ice-sheet retreat and bottom current strength on the western Barents Sea shelf

    Science.gov (United States)

    Lantzsch, Hendrik; Hanebuth, Till J. J.; Horry, Jan; Grave, Marina; Rebesco, Michele; Schwenk, Tilmann

    2017-10-01

    High-resolution sediment echosounder data combined with radiocarbon-dated sediment cores allowed us to reconstruct the Late Quaternary stratigraphic architecture of the Kveithola Trough and surrounding Spitsbergenbanken. The deposits display the successive deglacial retreat of the Svalbard-Barents Sea Ice Sheet. Basal subglacial till indicates that the grounded ice sheet covered both bank and trough during the Late Weichselian. A glaciomarine blanket inside the trough coinciding with laminated plumites on the bank formed during the initial ice-melting phase from at least 16.1 to 13.5 cal ka BP in close proximity to the ice margin. After the establishment of open-marine conditions at around 13.5 cal ka BP, a sediment drift developed in the confined setting of the Kveithola Trough, contemporary with crudely laminated mud, an overlying lag deposit, and modern bioclastic-rich sand on Spitsbergenbanken. The Kveithola Drift shows a remarkable grain-size coarsening from the moat towards the southern flank of the trough. This trend contradicts the concept of a separated drift (which would imply coarser grain sizes in proximity of the moat) and indicates that the southern bank is the main sediment source for the coarse material building up the Kveithola Drift. This depocenter represents, therefore, a yet undescribed combination of off-bank wedge and confined drift. Although the deposits inside Kveithola Trough and on Spitsbergenbanken display different depocenter geometries, time-equivalent grain-size changes imply a region-wide sediment-dynamic connection. We thus relate a phase of coarsest sediment supply (8.8-6.3 cal ka BP) to an increase in bottom current strength, which might be related to a stronger Atlantic Water inflow from the Southeast across the bank leading to winnowing and off-bank export of sandy sediments.

  1. Spectroscopic Parameters for Ozone and its Isotopes: Current Status, Prospects for Improvement, and the Identification of 16O16O17O and O-16O-16O-17 and O-16O-17O-16 Lines in Infrared Ground-Based and Stratospheric Solar Absorption Spectra

    Science.gov (United States)

    Rinsland, C. P.; Flaud, J.-M.; Goldman, A.; Perrin, A.; Camy-Peyret, C.; Smith, M. A. H.; Devi, V. Malathy; Benner, D. C.; Barbe, A.; Stephens, T. M.; hide

    1998-01-01

    We describe the updates to the spectroscopic parameters of ozone and its isotopes in the 1996 HITRAN compilation. Recent published studies not included in HITRAN are also summarized. Finally, we report the identification of infrared lines of the v(sub 3) bands of O-16O-16O-17 and O-16O-17O-16 in high-resolution solar spectra recorded by stratospheric balloon-borne and ground-based Fourier transform spectrometers.

  2. Effects of ground motion spatial variation on seismic response of a power transmission tower-line system%地震动空间变化对高压输电塔线体系地震反应的影响

    Institute of Scientific and Technical Information of China (English)

    田利; 李宏男; 王文明

    2013-01-01

    Here, effects of ground motion spatial variation on seismic response of a power transmission tower-line system were studied with numerical simulations. A three-dimensional finite element model for the power transmission tower-line coupled system considering the geometric nonlinearity of transmission line was established. Based on wave passage effect, coherency loss effect, different local site effect and multi-dimensional nature of ground motion, spatially varying ground motion time histories were simulated according to power spectral density function, coherency loss function and Code for Design of Seismic of Electrical Installations. The effects of wave passage, coherency loss and different local site effect on the seismic response of the transmission tower-line system were investigated, respectively. The results showed that the effects of ground motion spatial variation have significant influence on the seismic response of the transmission tower-line system; neglecting these effects may underestimate the response of the structure; the effects of ground motion spatial variation should be considered in seismic design of transmission line practical engineering.%通过数值模拟研究了地震动空间变化对高压输电塔线体系地震反应的影响.建立了输电塔线耦联体系三维有限元模型,考虑了输电线的几何非线性特征;在考虑地震动的行波效应、部分相干效应和局部场地效应以及多维性基础上,依据功率谱密度函数、相干函数和《电力设施抗震设计规范》模拟了空间变化地震动时程;分别研究了地震动空间变化的行波效应、部分相干效应和局部场地效应对输电塔线体系地震反应的影响.研究结果表明,地震动空间变化对输电塔线体系地震反应影响显著,忽略这些因素将会低估结构的反应.因此对于输电线路实际工程的抗震设计,需要考虑地震动空间变化效应的影响.

  3. Scholarly Retreat

    Science.gov (United States)

    Boyle, Robert R.; Pellegrini, Barbara J.; McGrew, Jean B.

    2003-01-01

    Advanced placement teachers around Chicago find their own intellectual stimulation reinvigorates their teaching and benefits their students. Through a consortium, these teachers group together to explore content-based topics using a rich variety of community resources, including a top library, university and museum resources. "This is my…

  4. Mapping the Tidewater Submarine and Ice-Marginal Environment Using Interferometric Bathymetry, Ground-Based LiDAR and Current Velocities; Hubbard Glacier, Alaska

    Science.gov (United States)

    Finnegan, D. C.; Lawson, D. E.; Butler, W.; Waller, T.; Pratt, T.

    2009-12-01

    The seasonal advance and retreat of tidewater glaciers is a relatively well-documented phenomenon. But our understanding of the processes and conditions within the ice-marginal submarine environment that drive or result from this activity is limited. Capturing holistic information within this environment such as bathymetric topography, hydrographic measurements and geospatial information about the terminus itself is often limited to discrete measurements far from the terminus grounding line or lack the detail and scale necessary to identify features that may be indicative of process. To understand these processes, it is essential to accurately obtain data at resolutions that are sufficient to understand the geologic and marine environment. This paper describes the results of a first-of-its-kind survey of the submarine and ice-marginal terrestrial environment of the Hubbard Glacier tidewater terminus. Hubbard Glacier is the largest non-polar tidewater glacier in the world. It encompasses an area of 3500 sq km and flows 120 km from the flanks of Mt Logan (5959 m) in the Wrangell St. Elias Mountains (Canada) to sea level where its terminus widens to ~13 km. In contrast to most glaciers in Southeast Alaska, Hubbard Glacier continues to advance and thicken and is predicted to continue for the foreseeable future. We utilize a multi-sensor fusion approach that integrates high-resolution interferometric (swath-based) multibeam bathymetry with high-resolution ground-based LiDAR topography and current velocity profiles to provide a detailed look at the section of the glacier where significant ice advance and potential ice-damming occurs. Through simultaneous collection of these data we are able to precisely map the topography of the sea floor adjacent to and at the grounding line of the ice terminus while simultaneously mapping the ice terminus and surrounding terrain to create a complete 3D topographic model of the aerial and submarine environment. These data allow for

  5. Psychological Effects of a 1-Month Meditation Retreat on Experienced Meditators: The Role of Non-attachment

    Science.gov (United States)

    Montero-Marin, Jesus; Puebla-Guedea, Marta; Herrera-Mercadal, Paola; Cebolla, Ausias; Soler, Joaquim; Demarzo, Marcelo; Vazquez, Carmelo; Rodríguez-Bornaetxea, Fernando; García-Campayo, Javier

    2016-01-01

    Background: There are few studies devoted to assessing the impact of meditation-intensive retreats on the well-being, positive psychology, and personality of experienced meditators. We aimed to assess whether a 1-month Vipassana retreat: (a) would increase mindfulness and well-being; (b) would increase prosocial personality traits; and (c) whether psychological changes would be mediated and/or moderated by non-attachment. Method: A controlled, non-randomized, pre-post-intervention trial was used. The intervention group was a convenience sample (n = 19) of experienced meditators who participated in a 1-month Vipassana meditation retreat. The control group (n = 19) comprised matched experienced meditators who did not take part in the retreat. During the retreat, the mean duration of daily practice was 8–9 h, the diet was vegetarian and silence was compulsory. The Experiences Questionnaire (EQ), Non-attachment Scale (NAS), Positive and Negative Affect Schedule (PANAS), Satisfaction With Life Scale (SWLS), Temperament Character Inventory Revised (TCI-R-67), Five Facets Mindfulness Questionnaire (FFMQ), Self-Other Four Immeasurables (SOFI) and the MINDSENS Composite Index were administered. ANCOVAs and linear regression models were used to assess pre-post changes and mediation/moderation effects. Results: Compared to controls, retreatants showed increases in non-attachment, observing, MINDSENS, positive-affect, balance-affect, and cooperativeness; and decreases in describing, negative-others, reward-dependence and self-directedness. Non-attachment had a mediating role in decentring, acting aware, non-reactivity, negative-affect, balance-affect and self-directedness; and a moderating role in describing and positive others, with both mediating and moderating effects on satisfaction with life. Conclusions: A 1-month Vipassana meditation retreat seems to yield improvements in mindfulness, well-being, and personality, even in experienced meditators. Non-attachment might

  6. Exploring tidewater glacier retreat using past and current observations at Columbia Glacier, Alaska. (Invited)

    Science.gov (United States)

    O'Neel, S.; Pfeffer, W. T.; Howat, I. M.; Conway, H.; Columbia Glacier Consortium

    2010-12-01

    Since fulfilling Austin Post’s prediction of impending retreat in the late 1970s, Columbia Glacier has repeatedly surprised both casual and careful observers with its ability for rapid change. Over the last three decades, Columbia Glacier has lost approximately 18 km of its original 66 km length, while thinning by approximately 50% at the present terminus. The total ice volume lost to the Gulf of Alaska Estimates upwards of 120 km3 constrain the total ice volume lost to the Gulf of Alaska. Recently, the terminus supported a ~1.5 km long floating tongue for over than a year, contradicting the common assumption that the mechanical properties of temperate ice prohibit flotation over sustained time intervals. The rich history of study offers an opportunity to better understand tidewater glacier retreat, and a valuable analog to the dynamic instability underway at several ice sheet outlet glaciers. Current research aims to improve processing resolution of existing aerial photographic data, while complimenting the 30-year photogrammetric record with a suite of field observations. Recent instrumentation includes: oblique time lapse and still imagery, semi-permanent GPS, airborne radar, mass balance, passive seismology and LiDAR. This presentation will focus on innovative methods developed in recent field seasons, sharing insight each has provided into the retreat process . 1The Columbia Glacier Consortium consists of: Fabian Walter (SIO), Kenichi Matsuoka (NPI), Ben Smith (UW), Ethan Welty (CU-Boulder), Chris Larsen (UAF), Dave Finnegan (CRREL), Dan McNamara (USGS), Yushin Ahn (OSU), Julie Markus (OSU), Adam LeWinter (EIS).

  7. Modeling the cliff retreat response to base-level change in layered rocks, Colorado Plateau, USA

    Science.gov (United States)

    Ward, D.; Sheehan, C.

    2015-12-01

    The retreat of cliffs is an important mode of erosion in layered rocks of variable strength. For example, the iconic Colorado Plateau landscapes of Grand Canyon, Canyonlands, and Monument Valley owe their unique forms to this process. These landscapes are the end result of incision by trunk streams followed by cliff retreat. Local interactions between stochastic rockfall and first-order channels draining a cliff regulate the cliff retreat response to a base-level fall. However, nonlinear transport dynamics, steep slopes, and variable rock strength challenge the modeling of landscape evolution in these settings. Here, we employ structure-from-motion photogrammetry to generate high-resolution DTMs of a natural experiment site on the Colorado Plateau. The site features a simple, sandstone-over-shale stratigraphy with a continuous gradient in cliffband height and evidence for an ongoing transient response to base level fall. The terrain data inform a high-resolution (dx=5 m), 2D numerical model of cliffband erosion. The model simulates the interaction of three primary processes: fluvial erosion and sediment transport; hillslope transport of regolith, including shallow landsliding; and rockfall from resistant units. Crucially, the model allows us to modify stratigraphy arbitrarily to examine the landscape response to parameters such as thickness, spacing, and dip of resistant units. Results indicate that the contrast in fluvial erodibility sets the pattern of emergence of cliffs as a resistant layer is exhumed, while the difference in weathering rates across rock types sets the rate at which cliffs emerge. Once rockfall begins, erosion rates are modified by the thickness of the resistant layer, which sets the volume of rockfall debris reaching the channels below the cliff. The modeling highlights the need for process-based understanding of the conditions for cliff failure by rockfall and redistribution of the debris in very steep, rapidly-eroding landscapes.

  8. Risk factors for treatment default among re-treatment tuberculosis patients in India, 2006.

    Directory of Open Access Journals (Sweden)

    Ugra Mohan Jha

    Full Text Available SETTING: Under India's Revised National Tuberculosis Control Programme (RNTCP, >15% of previously-treated patients in the reported 2006 patient cohort defaulted from anti-tuberculosis treatment. OBJECTIVE: To assess the timing, characteristics, and risk factors for default amongst re-treatment TB patients. METHODOLOGY: For this case-control study, in 90 randomly-selected programme units treatment records were abstracted from all 2006 defaulters from the RNTCP re-treatment regimen (cases, with one consecutively-selected non-defaulter per case. Patients who interrupted anti-tuberculosis treatment for >2 months were classified as defaulters. RESULTS: 1,141 defaulters and 1,189 non-defaulters were included. The median duration of treatment prior to default was 81 days (25%-75% interquartile range 44-117 days and documented retrieval efforts after treatment interruption were inadequate. Defaulters were more likely to have been male (adjusted odds ratio [aOR] 1.4, 95% confidence interval [CI] 1.2-1.7, have previously defaulted anti-tuberculosis treatment (aOR 1.3 95%CI 1.1-1.6], have previous treatment from non-RNTCP providers (AOR 1.3, 95%CI 1.0-1.6], or have public health facility-based treatment observation (aOR 1.3, 95%CI 1.1-1.6. CONCLUSIONS: Amongst the large number of re-treatment patients in India, default occurs early and often. Improved pre-treatment counseling and community-based treatment provision may reduce default rates. Efforts to retrieve treatment interrupters prior to default require strengthening.

  9. Contributions of culture and antimicrobial susceptibility tests to the retreatment of patients with pulmonary tuberculosis

    Directory of Open Access Journals (Sweden)

    Bruno Horta Andrade

    2013-08-01

    Full Text Available Introduction This study evaluated the efficacy of retreatment of pulmonary tuberculosis (TB with regard to treatment outcomes and antimicrobial susceptibility testing (ST profiles. Methods This retrospective cohort study analyzed 144 patients treated at a referral hospital in Brazil. All of them had undergone prior treatment, were smear-positive for TB and received a standardized retreatment regimen. Fisher's 2-tailed exact test and the χ2 test were used; RRs and 95% CIs were calculated using univariate and multivariate binary logistic regression. Results The patients were cured in 84 (58.3% cases. Failure was associated with relapsed treatment and abandonment (n=34. Culture tests were obtained for 103 (71.5% cases; 70 (48.6% had positive results. ST results were available for 67 (46.5% cases; the prevalence of acquired resistance was 53.7%. There were no significant differences between those who achieved or not therapeutic success (p=0.988, despite being sensitive or resistant to 1 or more drugs. Rifampicin resistance was independently associated with therapeutic failure (OR: 4.4, 95% CI:1.12-17.37, p=0.034. For those cases in which cultures were unavailable, a 2nd model without this information was built. In this, return after abandonment was significantly associated with retreatment failure (OR: 3.59, 95% CI:1.17-11.06, p=0.026. Conclusions In this cohort, the general resistance profile appeared to have no influence on treatment outcome, except in cases of rifampicin resistance. The form of reentry was another independent predictor of failure. The use of bacterial culture identification and ST in TB management must be re-evaluated. The recommendations for different susceptibility profiles must also be improved.

  10. Glacier Retreat in the Southern Peruvian Andes: Climate Change, Environmental Impacts, Human Perception and Social Response

    Science.gov (United States)

    Orlove, B.

    2007-12-01

    This paper presents results from recent environmental and anthropological research near glacierized areas in the department of Cusco, Peru, home to the well-known Quelccaya Ice Cap and to the peak of Ausangate (6384 m). Glaciers in the region are in negative mass balance, losing volume and area, with upslope movement of the glacier fronts. Somewhat paradoxically, flows in many streams close to the glaciers are reduced, particularly in the dry season, due to a shift in the seasonal distribution of melting, to increased evaporation and to increased percolation into newly-exposed sands and gravels. Associated with this reduction in flow is a desiccation of some anthropogenic and natural wetlands, reducing the availability of dry season forage to wild (vicuna) and domesticated (alpaca, llama) ruminants. Interviews and ethnographic observations with local populations of Quechua-speaking herders at elevations of 4500-5200 meters provide detailed comments on these changes. They have an extensive vocabulary of terms for glacial features associated with retreat. They link this treat with environmental factors (higher temperatures, greater winds that deposit dust on lower portions of glaciers) and with religious factors (divine punishment for human wrong-doing, failure of humans to respect mountain spirits). They describe a variety of economic and extra-economic impacts of this retreat on different spatial, social and temporal scales. Though they face other issues as well (threats of pollution from new mining projects, inadequacy of government services), glacier retreat is their principal concern. Many herders express extreme distress over this unprecedented threat to their livelihoods and communities, though a few propose responses - out-migration, the formation of an association of neighboring communities, development of irrigation works - that could serve as adaptations.

  11. Early ice retreat and ocean warming may induce copepod biogeographic boundary shifts in the Arctic Ocean

    Science.gov (United States)

    Feng, Zhixuan; Ji, Rubao; Campbell, Robert G.; Ashjian, Carin J.; Zhang, Jinlun

    2016-08-01

    Early ice retreat and ocean warming are changing various facets of the Arctic marine ecosystem, including the biogeographic distribution of marine organisms. Here an endemic copepod species, Calanus glacialis, was used as a model organism, to understand how and why Arctic marine environmental changes may induce biogeographic boundary shifts. A copepod individual-based model was coupled to an ice-ocean-ecosystem model to simulate temperature- and food-dependent copepod life history development. Numerical experiments were conducted for two contrasting years: a relatively cold and normal sea ice year (2001) and a well-known warm year with early ice retreat (2007). Model results agreed with commonly known biogeographic distributions of C. glacialis, which is a shelf/slope species and cannot colonize the vast majority of the central Arctic basins. Individuals along the northern boundaries of this species' distribution were most susceptible to reproduction timing and early food availability (released sea ice algae). In the Beaufort, Chukchi, East Siberian, and Laptev Seas where severe ocean warming and loss of sea ice occurred in summer 2007, relatively early ice retreat, elevated ocean temperature (about 1-2°C higher than 2001), increased phytoplankton food, and prolonged growth season created favorable conditions for C. glacialis development and caused a remarkable poleward expansion of its distribution. From a pan-Arctic perspective, despite the great heterogeneity in the temperature and food regimes, common biogeographic zones were identified from model simulations, thus allowing a better characterization of habitats and prediction of potential future biogeographic boundary shifts.

  12. Autocyclic Formation, Retreat, and Destruction of Waterfalls in an Experimental Bedrock Channel

    Science.gov (United States)

    Scheingross, J. S.; Fuller, B. M.; Lamb, M. P.

    2015-12-01

    Waterfalls are ubiquitous in steep landscapes and have been documented to retreat upstream at rates far outpacing standard fluvial incision into bedrock. While the formation of waterfalls following changes in climate and base-level lowering have been well-documented, little work has explored the formation of waterfalls via the internal dynamics from interacting flow hydraulics, sediment flux, and evolving channel morphology. Distinguishing between waterfalls formed via external versus internal forcing is important, as waterfall formation and retreat rate is often applied in inverse to determine the timing of external forcing. Here, we present results from a laboratory experiment designed to explore channel incision and waterfall formation. We fed water and sediment at constant rates over an initially planar surface at 19.5% slope. A channel rapidly incised into the artificial bedrock substrate, and small-wavelength variations in erosion rate created steps and pools which grew in amplitude. As pools deepened, erosion was focused on the upstream pool faces creating steep segments in the channel bed. At the topographic breaks between these steep segments and their upstream treads, water detached from the bed forming ventilated waterfall jets which impacted the plunge pools below. Continued pool deepening led to sediment deposition on the pool floors, locally inhibiting vertical incision while the upstream and downstream surfaces were free to erode. Amplified erosion at the waterfall lip incised a new pool into the bedrock previously composing the waterfall face while simultaneous lowering of the downstream pool lip resulted in the destruction of the original pool. Repetition of this process in our experiment suggests that interactions between bedrock erosion and sediment cover can result in the formation of a series of plunge pools which retreat upstream, and that care must be taken to distinguish between autocyclic versus allocyclic waterfall formation in studies

  13. Tectonic, lithologic and climatic controls on knickpoint retreat rates and landscape response times

    Science.gov (United States)

    Whittaker, Alexander; Boulton, Sarah; Kent, Emiko; Alçiçek, Cihat

    2016-04-01

    The plan-view and vertical rates at which transient knickpoints propagate through a landscape fundamentally controls geomorphic response times to tectonic and climatic perturbations. Here we present knickpoint retreat rates upstream of active faults for bedrock catchments in the Gediz graben of Turkey where past climate is well documented but where the history of faulting is not fully constrained. The rivers upstream of the normal fault-bounded graben each contain a non-lithologic knickpoint, including those that drain through inferred fault segment boundaries. Knickpoint heights measured vertically from the fault scale with footwall relief and documented fault throw (vertical displacement). Consequently, we deduce these knickpoints were initiated by an increase in slip rate on the basin-bounding fault, driven by linkage of the three main fault segments of the high-angle graben-bounding fault array. Fault interaction theory and ratios of channel steepness suggest that the slip rate enhancement factor on linkage was a factor of 3. We combine this information with geomorphic and structural constraints to estimate that linkage took place between 0.6 Ma and 1 Ma. Calculated pre- and post- linkage throw rates are 0.6 and 2 mm/yr respectively. Maximum plan-view knickpoint retreat rates upstream of the faults range from 4.5 to 28 mm/yr, and when normalised by drainage area, they are 2-7 times faster than for similar catchments upstream of normal faults in the Central Apennines of Italy and the Hatay Graben of Turkey. These knickpoint retreat rates imply a fluvial response time to fault growth and interaction of 1.6 to 2.7 My. However, marked along-strike disparities in retreat rates exist. We demonstrate that climate differences may explain the variation in rates between these study areas, but not within the Gediz graben itself. Consequently, we evaluate the extent to which measureable differences in bedrock lithology and erodibility modulate the propagation of

  14. Oncology Nurse Retreat: A Strength-Based Approach to Self-Care and Personal Resilience
.

    Science.gov (United States)

    Kuglin Jones, Ann

    2017-04-01

    Oncology nurses are at high risk for burnout and compassion fatigue. Self-care is an essential element that oncology nurses should incorporate into their daily lives but, instead, is often deprioritized. As a result, nurses do not seek out educational opportunities that focus on self-care or personal growth. This article describes the curriculum that was developed for an oncology nurse retreat that promoted self-care and building personal resilience using tools that could be adapted for use with patients and families.
.

  15. Investigators Retreat: A Forum to Bridge Frederick and Bethesda Cancer Research | Poster

    Science.gov (United States)

    By Andrea Frydl, Contributing Writer Nearly 700 researchers, scientists, and laboratory technicians convened in the Ronald Reagan Building and International Trade Center in Washington, DC, for the 2014 NCI Intramural Scientific Investigators Retreat on Jan. 14. The event featured presentations and posters exploring topics in cancer research from KRAS signaling to animal care. One of the highlights of the event was a presentation made by Valerie Beral, Ph.D., from University of Oxford, discussing “Rosalind Franklin and Cancer in Women.” 

  16. Two-Day Curriculum Retreat: An Innovative Response to the Call for Reform.

    Science.gov (United States)

    Lane, Adrianne J; Mitchell, Claudia G

    2015-01-01

    This article outlines processes followed during a two-day offsite retreat for nurse faculty planned for the purpose of curricular redesign and content mapping. Faculty identified and leveled content for all baccalaureate clinical courses and engaged in dialogue specific to promoting student connections between didactic and clinical outcomes. Faculty developed two core simulation scenarios for every clinical course and leveled learning outcomes for each. Faculty defined where within the curriculum key concepts were introduced and planned depth of knowledge, application, and synthesis from sophomore through senior levels. Evaluation revealed the process led faculty to a stronger overall understanding of the curriculum.

  17. Spatial and Temporal Changes in Bank Retreat Rates in a Small Headwater Stream

    Science.gov (United States)

    Utley, B. C.; Wynn, T. M.

    2008-12-01

    Streambank retreat varies both spatially and temporally within any given system due to natural variability in both soil characteristics and hydraulic flow patterns. This study analyzes one year of monthly erosion pin data for Stroubles Creek, a small, urban, headwater stream in southwestern Virginia near the town of Blacksburg. The 400-m long study reach has 250 erosion pins installed on actively eroding streambanks. The pins are spaced every 10 m along the stream length, with 2-m spacing on more active section. Vertical pin spacing is 30 cm, starting at the bank toe. Streambank retreat rates were measured monthly from August 2005 to May 2007. The retreat data were evaluated for significant spatial patterns and correlation to climatic factors using Shapiro-Wilk test for normality and Kruskal-Wallis test for difference between groups. While spatial differences in retreat rates were not statistically significant, temporal variation was (p=0.0007): the highest erosion occurred during winter months of 2006 and 2007. The only exception to this trend occurred in July 2006, when a large, out-of-bank storm event occurred. Monthly erosion rates were calculated by two methods. The volume of bank eroded is often calculated from erosion pin data by averaging the measurements from several pins over a bank area then multiplying the average by the rough area of that bank. This study compared the results of the averaging method to a spatial interpolation and integration method computed with the computer program SURFER. The surfer analysis compared two surfaces, a surface of change to a plane with a value of zero. Theoretically, the spatial interpolation/integration technique allows more of the natural variability of system to be recognized and included in the calculations. The significant difference between volume calculation techniques is interesting, for 12 of 15 bank areas the averaging method estimated more erosion during the study period than the interpolation technique

  18. Nutrient biogeochemistry of the eastern Arabian Sea during the southwest monsoon retreat

    Digital Repository Service at National Institute of Oceanography (India)

    George; Muraleedharan, K.R.; Martin, G.D.; Sabu, P.; Gerson, V.J.; Dineshkumar, P.K.; Nair, S.M.; Chandramohanakumar, N.; Nair, K.K.C.

    ARTICLE Nutrient biogeochemistry of the eastern Arabian Sea during the southwest monsoon retreat Rejomon George • K. R. Muraleedharan • G. D. Martin • P. Sabu • Vijay John Gerson • P. K. Dineshkumar • S. M. Nair • N. Chandramohanakumar • K. K. C. Nair... monsoon between 8�N and 21�N, when the surface currents are southward and the subsurface R. George � K. R. Muraleedharan � G. D. Martin � P. Sabu � V. J. Gerson � P. K. Dineshkumar � K. K. C. Nair National Institute of Oceanography, Council of Scientific...

  19. Surgical management of an endodontic retreatment failure of a mandibular first molar

    Directory of Open Access Journals (Sweden)

    Kinjal M Gathani

    2016-01-01

    Full Text Available One of the common endodontic iatrogenic mishaps is the extrusion of obturation material which has a negative effect on the long-term prognosis of the tooth. Surgical endodontics has enabled us to save teeth with persistent infections and extrusions when orthograde treatment has been unsuccessful. Apicoectomy of the molars is not frequently performed even though its success rate can reach that of anteriors and premolars. This case report describes the orthograde and surgical management of a mandibular first molar with external root resorption, instrument separation in the canal, and extruded obturation material, which had been unresponsive to endodontic retreatment.

  20. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    Science.gov (United States)

    Coupel, P.; Jin, H. Y.; Ruiz-Pino, D.; Chen, J. F.; Lee, S. H.; Li, H. L.; Rafizadeh, M.; Garçon, V.; Gascard, J. C.

    2011-07-01

    A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA) ocean during a year of exceptional ice retreat (August-September 2008). This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC) and taxonomy (microscopy) acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N) to extreme high latitudes over the Alpha Ridge (86° N) encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin. Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1-5 mg m-3) dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (poverty (Canadian Basin) and the richness (Chukchi shelf) of the WA, we explore the role of the nutrient-rich Pacific Waters, the bathymetry and two characteristics linked to the intense ice retreat: the stratification and the Surface Freshwater Layer (SFL). The freshwater accumulation induced a strong stratification limiting the nutrient input from the subsurface Pacific waters. This results in a biomass impoverishment of the well-lit layer and compels the phytoplankton to grow in subsurface. The phytoplankton distribution in the Chukchi Borderland and north Canadian Basin, during the summer of exceptional ice retreat (2008), suggested when compared to in-situ data from a more ice covered year (1994), recent changes with a decrease of the phytoplankton abundance while averaged biomass was similar. The 2008 obtained phytoplankton data in the WA provided a state of the ecosystem which

  1. Analysis on Zero Sequence Current Distribution Characteristic of Grounding Faults Occurred in Double-Circuit Transmission Lines on The Same Tower%同塔双回线路接地故障零序电流分布特性分析

    Institute of Scientific and Technical Information of China (English)

    曾耿晖; 蔡泽祥; 陈桥平; 刘为雄

    2011-01-01

    The distribution regularity of zero-sequence current, which appears during external and internal grounding faults occurred in double-circuit transmission lines on the same tower under different operation modes, different zero-sequence mutual inductance and different fault locations, is analyzed. For external grounding faults, the impact of different zero-sequence impedance of double-circuit transmission lines on the same tower is mainly considered; for internal grounding faults, the impacts of zero-sequence mutual inductances and fault locations under following conditions are considered: parallel operation of both transmission lines; one transmission line is energized and in the stand-by state while the other one is artificially grounded for the maintenance. The effects of "zero-sequence magnetic assist" and "zero-sequence degaussing", which are caused by the flowing of zero-sequence currents of both transmission lines on the same tower in the same direction and by those in the opposite direction respectively, lead to variation of distribution regularity of zero-sequence currents, and in extreme circumstance the out-of-limit of the first zone of zero-sequence over-current protection may occur. Based on practical calculation examples of Guangdong power grid, the setting measures are put forward to avoid the out-of-limit of the first zone of zero-sequence over-current protection for double-circuit transmission lines on the same tower. It is also proposed that in the setting of the first zone of zero-sequence over-current protection for double-circuit transmission lines on the same tower, the comprehensive effects of operation modes of double-circuit transmission lines on the same tower, the extent of zero-sequence mutual induction and fault locations should be taken into account to avoid the malfunction of the first zone of zero-sequence over-current protection of adjacent healthy transmission lines due to the affect of mutual induction while grounding

  2. Little ice age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia, recorded in maps, air photographs and dendrochronology

    Directory of Open Access Journals (Sweden)

    A. Rivera

    2011-10-01

    Full Text Available Glaciar Jorge Montt (48°20' S/73°30' W, one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI, has experienced the fastest frontal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This record retreat uncovered trees overridden during the Little Ice Age (LIA advance of the glacier. Samples of these trees were dated using radiocarbon methods, yielding burial ages between 460 and 250 cal yr BP. The dendrochronology and maps indicate that Glaciar Jorge Montt was at its present position before the beginning of the LIA, in concert with several other glaciers in Southern Patagonia, and reached its maximum advance position between 1650 and 1750 AD. The post-LIA retreat is most likely triggered by climatically induced changes during the 20th century, however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a new fjord 19.5 km long, and up to 391 m deep, with a varied bathymetry well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

  3. Relation between etch-pit morphology and step retreat velocity on a calcite surface in aspartic acid solution

    Science.gov (United States)

    Yoshino, Toru; Kagi, Hiroyuki; Kamiya, Natsumi; Kokawa, Ryohei

    2010-04-01

    Effects of L-aspartic acid ( L-Asp) on dissolution of calcite were investigated. The step retreat velocity and dissolution rate of calcite were measured simultaneously using an AFM flow-through system. The etch-pit morphology of calcite was observed using confocal laser scanning microscopy. Results show that the etch-pit morphologies changed drastically depending on the L-Asp concentration ([ L-Asp]) in the order of rhomboidal, pentagonal, and triangular (not perfectly, but retaining an extra step). The change in obtuse step directions and appearance of the [0 1 0] step triggered these morphological changes. Addition of L-Asp accelerated all step retreats at [ L-Asp]0.01 M, L-Asp inhibited the retreats of obtuse steps and [0 1 0] step, although the retreat velocities of acute steps were constant irrespective of [ L-Asp]. These results suggest that the directional changes and the inhibition of retreat velocities of obtuse steps were attributed to the generation of [ 4 1 1] and [4 5 1] steps caused by L-Asp. Moreover, we confirmed the preferential effects of L-Asp on the [4 8 1] + to [ 4 4 1] ± step edge, and proposed the preferential effects of L-Asp on the [ 4 1 1] to [4 5 1] step edge.

  4. A team-based approach to qualitative inquiry: the collaborative retreat.

    Science.gov (United States)

    Lordly, Daphne; Maclellan, Debbie; Gingras, Jacqui; Brady, Jennifer

    2012-01-01

    A team of researchers undertook a collaborative qualitative study to explore beginning dietitians' life experiences and the meaning ascribed to those experiences in the context of dietetic practice. Data were collected using Seidman's three-step in-depth phenomenological interviewing method with 12 beginning dietitians who were graduates of the three participating dietetic programs. We outline the collaborative research process and highlight a writing and data analysis technique described as the collaborative retreat, a face-to-face, two-day gathering that facilitated the researchers' collective decision-making and organization, discussion, and analysis of this complex qualitative data set. Use of a listening guide aided researchers' understanding and interpretation of participant voices. Researchers concluded that the overall collaborative qualitative research process was positive and self-fulfilling, and that it resulted in multiple benefits for them individually and the research project collectively. Researchers were able to work through methodological and theoretical issues as these arose, with the assistance of technology, writing, listening, and dialogue. Relationship building and relationship maintenance emerged as factors critical to the success of the research process. Collaborative research teams that are committed to listening, writing, and dialogue will find that the collaborative retreat can be a productive site of knowledge generation and mentorship.

  5. A plastic network approach to model calving glacier advance and retreat

    Science.gov (United States)

    Ultee, Lizz; Bassis, Jeremy N.

    2017-03-01

    Calving glaciers contribute substantially to sea level rise, but they are challenging to represent in models. Fine resolution is required for continental-scale models to accurately resolve calving dynamics and in many cases glacier geometry is too complicated to be adequately reflected by more simplified models. Flowline models are able to resolve flow along the main branch of a glacier, but many of those in current use either ignore tributaries entirely or parameterize their effect using a measure of “equivalent width”. Here we present a simple method to simulate terminus advance and retreat for an interacting network of glacier branches, based on a model extending Nye’s 1953 perfect plastic flow approximation to calving glaciers. We apply the method to case studies of four marine-terminating glaciers: Jakobshavn Isbræ and Helheim Glacier of Greenland, and Columbia and Hubbard Glaciers of Alaska. Given bed topography and upstream elevation history, our method reproduces observed patterns of terminus advance and retreat in all cases, as well as centerline profiles for all branches.

  6. Regenerative Endodontic Treatment as a Retreatment Option for a Tooth with Open Apex - A Case Report.

    Science.gov (United States)

    Miltiadous, Maria-Elpida A; Floratos, Spyros G

    2015-10-01

    Treatment of non-vital immature teeth with apical periodontitis has always been a challenge in Endodontics. Regenerative endodontic treatment (RET) has been successfully used for the management of these cases. The aim of this study is to present a case of RET used for the retreatment of a previously endodontically treated permanent tooth with an open apex. A 14-year-old boy with a poor endodontic treatment done on his maxillary right central incisor developed symptomatic apical periodontitis. Radiographically, incomplete root development with thin dentinal walls and an open apex were evident. After accessing and removing previous filling materials, the canal was copiously irrigated with 2.5% sodium hypochlorite. A triple antibiotic paste was placed inside the canal and left for 15 days. After removal of the antibiotic mixture, bleeding was induced into the canal by passing a hand file out of the apex. A collagen membrane barrier was placed over the blood clot, followed by sealing with mineral trioxide aggregate. Access was sealed with permanent filling materials. Clinical examination at 12, 24 and 36 months revealed no symptoms. Radiographic examination showed resolution of the periapical lesion and apical closure. Sensitivity tests with cold and an electric pulp test elicited a negative response at all recall periods. On the basis of long-term results, RET may be an effective option for the retreatment of an immature permanent tooth with a failed previous treatment and periapical periodontitis.

  7. Differential timing of C4 plant decline and grassland retreat during the penultimate deglaciation

    Science.gov (United States)

    He, Juan; Jia, Guodong; Li, Li; Wang, Pinxian

    2017-09-01

    Compound-specific stable carbon isotope composition of terrestrial leaf wax n-alkyl lipids (δ13Calk) was measured in sediments from the northern South China Sea (SCS), allowing assessment of vegetation change in the source area within the penultimate glacial cycle during 60-160 kyr. Our δ13Calk record suggested a prominent vegetation contrast between the glacial and the interglacial, with more C4 plant developing during the glaciation and a rapid decline during the glacial termination. This deglacial change in δ13Calk was attributed to an increase in humidity caused by the enhancement of the East Asian Summer Monsoon (EASM). However, the inferred deglacial C4 decline lagged by 4 kyr behind the grass retreat inferred from published pollen record. We argue that the time discrepancy in the two terrestrial plant proxies may have resulted from their differential responses to regional climate change, with grass community structure more sensitive to temperature rise and plant photosynthetic pathway more sensitive to humidity increase. Therefore, an earlier penultimate deglacial warming relative to humidity increase can be inferred from the lead of grass retreat relative to C4 decline, which implies that EASM may be delayed during the deglacial warming.

  8. The future of ice sheets and sea ice: between reversible retreat and unstoppable loss.

    Science.gov (United States)

    Notz, Dirk

    2009-12-08

    We discuss the existence of cryospheric "tipping points" in the Earth's climate system. Such critical thresholds have been suggested to exist for the disappearance of Arctic sea ice and the retreat of ice sheets: Once these ice masses have shrunk below an anticipated critical extent, the ice-albedo feedback might lead to the irreversible and unstoppable loss of the remaining ice. We here give an overview of our current understanding of such threshold behavior. By using conceptual arguments, we review the recent findings that such a tipping point probably does not exist for the loss of Arctic summer sea ice. Hence, in a cooler climate, sea ice could recover rapidly from the loss it has experienced in recent years. In addition, we discuss why this recent rapid retreat of Arctic summer sea ice might largely be a consequence of a slow shift in ice-thickness distribution, which will lead to strongly increased year-to-year variability of the Arctic summer sea-ice extent. This variability will render seasonal forecasts of the Arctic summer sea-ice extent increasingly difficult. We also discuss why, in contrast to Arctic summer sea ice, a tipping point is more likely to exist for the loss of the Greenland ice sheet and the West Antarctic ice sheet.

  9. River piracy and drainage basin reorganization led by climate-driven glacier retreat

    Science.gov (United States)

    Shugar, Daniel H.; Clague, John J.; Best, James L.; Schoof, Christian; Willis, Michael J.; Copland, Luke; Roe, Gerard H.

    2017-04-01

    River piracy--the diversion of the headwaters of one stream into another one--can dramatically change the routing of water and sediment, with a profound effect on landscape evolution. Stream piracy has been investigated in glacial environments, but so far it has mainly been studied over Quaternary or longer timescales. Here we document how retreat of Kaskawulsh Glacier--one of Canada's largest glaciers--abruptly and radically altered the regional drainage pattern in spring 2016. We use a combination of hydrological measurements and drone-generated digital elevation models to show that in late May 2016, meltwater from the glacier was re-routed from discharge in a northward direction into the Bering Sea, to southward into the Pacific Ocean. Based on satellite image analysis and a signal-to-noise ratio as a metric of glacier retreat, we conclude that this instance of river piracy was due to post-industrial climate change. Rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems, sediment and carbon budgets, and downstream communities that rely on a stable and sustained discharge. We suggest that the planforms of Slims and Kaskawulsh rivers will adjust in response to altered flows, and the future Kaskawulsh watershed will extend into the now-abandoned headwaters of Slims River and eventually capture the Kluane Lake drainage.

  10. Retreat of glaciers on Puncak Jaya, Irian Jaya, determined from 2000 and 2002 IKONOS satellite images

    Science.gov (United States)

    Klein, Andrew G.; Kincaid, Joni L.

    Puncak Jaya, Irian Jaya, Indonesia, contains the only remaining tropical glaciers in East Asia. The extent of the ice masses on Puncak Jaya has been mapped from high-resolution IKONOS satellite images acquired on 8 June 2000 and 11 June 2002. Exclusive of Southwall Hanging Glacier, the ice extent on Puncak Jaya was 2.326 km2 and 2.152 km2 in 2000 and 2002, respectively. From 2000 to 2002, the Puncak Jaya glaciers lost a surface area of 0.174 km2 or 7.48% of their 2000 ice extent. Comparison of the IKONOS-based glacier extents with previous glacier extents demonstrates a continuing reduction of ice area on Puncak Jaya. By 2000, ice extent on Puncak Jaya had reduced by 88% of its maximum neoglacial extent. Between 1992 and 2000 Meren Glacier disappeared entirely. All remaining ice masses on Puncak Jaya continue their retreat from their neoglacial maxima. Comparison of 2000/2002 ice extents with previous extents suggests that these glaciers have not experienced accelerating rates of retreat during the last half of the 20th century. If the recession rates observed from 2000 to 2002 continue, the remaining ice masses on Puncak Jaya will melt within 50 years.

  11. Sea-ice retreat controls timing of summer plankton blooms in the Eastern Arctic Ocean

    Science.gov (United States)

    Janout, Markus A.; Hölemann, Jens; Waite, Anya M.; Krumpen, Thomas; Appen, Wilken-Jon; Martynov, Fedor

    2016-12-01

    Two full-year mooring records of sea-ice, physical, and bio-optical parameters illuminate tight temporal coupling between the retreating seasonal ice edge and the summer phytoplankton bloom on the Laptev Sea shelf. Our records showed no sign of pelagic under-ice blooms despite available nutrients and thinning sea ice in early summer, presumably because stratification had not yet developed. Chlorophyll blooms were detected immediately after the ice retreated in late May 2014 and late July 2015. Despite radically different timing, the blooms were similar in both magnitude and length, interpreted as community-level nutrient limitation. Acoustic backscatter records suggest the delayed 2015 bloom resulted in lower zooplankton abundance, perhaps due to a timing mismatch between ice algal and pelagic blooms and unfavorable thermal conditions. Our observations provide classical examples of ice-edge blooms and further emphasize the complexity of high-latitude shelves and the need to understand vertical mixing processes important for stratification and nutrient fluxes.

  12. Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming

    Science.gov (United States)

    Abe, Manabu; Nozawa, Toru; Ogura, Tomoo; Takata, Kumiko

    2016-11-01

    This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere-ocean general circulation model MIROC5. Arctic sea ice has been substantially retreating since the 1980s, particularly in September, under simulated global warming conditions. The simulated sea ice reduction is consistent with satellite observations. On the other hand, Arctic cloud cover has been increasing in October, with about a 1-month lag behind the sea ice reduction. The delayed response leads to extensive sea ice reductions because the heat and moisture fluxes from the underlying open ocean into the atmosphere are enhanced. Sensitivity experiments with the atmospheric part of MIROC5 clearly show that sea ice reduction causes increases in cloud cover. Arctic cloud cover increases primarily in the lower troposphere, but it decreases in the near-surface layers just above the ocean; predominant temperature rises in these near-surface layers cause drying (i.e., decreases in relative humidity), despite increasing moisture flux. Cloud radiative forcing due to increases in cloud cover in autumn brings an increase in the surface downward longwave radiation (DLR) by approximately 40-60 % compared to changes in clear-sky surface DLR in fall. These results suggest that an increase in Arctic cloud cover as a result of reduced sea ice coverage may bring further sea ice retreat and enhance the feedback processes of Arctic warming.

  13. Reversability of arctic sea ice retreat - A conceptual multi-scale modeling approach

    Science.gov (United States)

    Mueller-Stoffels, Marc

    The ice-albedo feedback has been identified as an important factor in the decay of the Arctic sea ice cover in a warming climate. Mechanisms of transition from perennial ice cover to seasonal ice cover are discussed in the literature; the existence of a tipping point is disputed. A newly developed regular network model for energy exchange and phase transition of an ice covered ocean mixed layer is introduced. The existence of bistability, a key ingredient for irreversibility, on local and regional scales is explored. It is shown in a spatially confined model that the asymptotic behavior and the existence of a parameter region of bistability strongly depend on the albedo parametrization. The spatial dynamics of sea ice retreat are studied for a high resolution latitudinal model of the ocean mixed layer. This regional model suggests that sea ice retreat is reversible. It is shown that laterally driven melt of thick multi-year sea ice, and thus, ice-albedo feedback, is an important mechanism in the transition from perennial to seasonal ice cover at the pole. Results are used to interpret observed changes in the recent ice extent and ice volume record. It is shown that the effectiveness of ice-albedo feedback strongly depends on the existence of lateral heat transfer mechanisms in the ocean.

  14. Using timing of ice retreat to predict timing of fall freeze-up in the Arctic

    Science.gov (United States)

    Stroeve, Julienne C.; Crawford, Alex D.; Stammerjohn, Sharon

    2016-06-01

    Reliable forecasts of the timing of sea ice advance are needed in order to reduce risks associated with operating in the Arctic as well as planning of human and environmental emergencies. This study investigates the use of a simple statistical model relating the timing of ice retreat to the timing of ice advance, taking advantage of the inherent predictive power supplied by the seasonal ice-albedo feedback and ocean heat uptake. Results show that using the last retreat date to predict the first advance date is applicable in some regions, such as Baffin Bay and the Laptev and East Siberian seas, where a predictive skill is found even after accounting for the long-term trend in both variables. Elsewhere, in the Arctic, there is some predictive skills depending on the year (e.g., Kara and Beaufort seas), but none in regions such as the Barents and Bering seas or the Sea of Okhotsk. While there is some suggestion that the relationship is strengthening over time, this may reflect that higher correlations are expected during periods when the underlying trend is strong.

  15. Apical extrusion of debris by supplementary files used for retreatment: An ex vivo comparative study

    Directory of Open Access Journals (Sweden)

    Ajinkya M Pawar

    2016-01-01

    Full Text Available Aim: This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs increased the debris extrusion apically. Materials and Methods: Eighty mandibular premolars with single root and canal were instrumented with ProTaper Universal rotary system (SX-F3 and obturated. The samples were divided randomly into four groups (n = 20. Group 1 served as a control; only ProTaper Universal RFs D1-D3 were used, and the extruded debris was weighed. Groups 2, 3, and 4 were the experimental groups, receiving a twofold retreatment protocol: Removal of the bulk, followed by the use of supplementary files. The bulk was removed by RFs, followed by the use of ProTaper NEXT (PTN, WaveOne (WO, and Self-Adjusting File (SAF for removal of the remaining root filling residues. Debris extruded apically were weighed and compared to the control group. Statistical analysis was performed using one-way analysis of variance (ANOVA and post hoc Tukey′s test. Results: All the three experimental groups presented significant difference (P < .01. The post hoc Tukey′s test confirmed that Group 4 (SAF exhibited significantly less (P < .01 debris extrusion between the three groups tested. Conclusion: SAF results in less extrusion of debris when used as supplementary file to remove root-filling residues, compared to WO and PTN.

  16. Magnetic bearing optical delay line

    NARCIS (Netherlands)

    Dool, T.C. van den; Kamphues, F.G.; Fouss, B.; Henrioulle, K.; Hogenhuis, H.

    2004-01-01

    TNO TPD, in close cooperation with Micromega-Dynamics and Dutch Space, has developed an advanced Optical Delay Line (ODL) for use in PRIMA, GENIE and other ground based interferometers. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task.

  17. Grounded coplanar waveguide defected ground structure enabled mulitlayered passive circuits

    Science.gov (United States)

    Schlieter, Daniel Benjamin

    Passive circuits are essential to microwave and millimeter-wave (mm-wave) frequency design, especially as new commercial applications emerge for complementary metal-oxide semiconductor (CMOS) integrated circuits. However, it is challenging to design distributed passive circuits for CMOS due to the substrate loss and thin dielectric layers of the back-end-of-line (BEOL). Furthermore, distributed passive circuits need to be adapted for compactness and integration while overcoming these challenges and maintaining high performance. Grounded coplanar waveguide defected ground structures meet this need for compact and integrable passive circuits by utilizing the top and bottom ground planes of the transmission line to implement circuit elements. Defected ground structures (DGS) are distributed elements realized by etching specific patterns into the ground planes of transmission lines. These structures can be used in conjunction with the center conductor of planar transmission lines to reduce circuit size and/or improve performance. By implementing DGS in grounded coplanar waveguide (GCPW) multiple resonances and higher impedances can be achieved. The resonant-based GCPW DGS are more compact than their microstrip and CPW counterparts and fit well into the vertical technology of back-end-of-line CMOS. This research demonstrates up to 80% size reduction at 5.8GHz by realizing spiral-shaped DGS in GCPW and applying the resulting GCPW DGS unit cell to a dual-behavior band-pass filter. The filter has been scaled to 60GHz and realized in a 130nm CMOS process by using floating metal strips to reduce the impact of the lossy silicon substrate. The impedance-based GCPW DGS, called EG-GCPW, have up to a 20:1 impedance ratio on Rogers RT/DuroidRTM 5880 and an impedance ratio of 15:1 on a benzocyclobutene post-CMOS process. These high impedance ratios increased the power division ratio of an unequal Wilkinson power divider to 7:1 and reduced the size of a stepped impedance low

  18. New cosmogenic exposure dates from Sermilik Fjord, southeast Greenland document rapid early Holocene retreat of Helheim Glacier

    Science.gov (United States)

    Hughes, A. L.; Rainsley, E.; Murray, T.; Fogwill, C. J.

    2010-12-01

    Marine-terminating glaciers are currently the dominant route for mass loss from the Greenland Ice Sheet (GrIS). Over the last decade Helheim Glacier, in concert with the majority of marine-terminating glaciers of the southeast sector of the GrIS, has exhibited dramatic changes in speed, thinning and retreat rates. The Holocene retreat history of the outlet glaciers of southeast Greenland is, however, largely unconstrained. Without detailed records of retreat over longer-time scales recent changes cannot be placed in context, nor is there sufficient evidence to constrain ice sheet models for improved estimates of future sea level rise. We present the first direct chronological constraint on the retreat of ice from Sermilik Fjord in southeast Greenland, the former drainage route of Helheim Glacier. Samples spanning the full length of the 80 km fjord were collected from erratics and streamlined bedrock in July 2009-10 and analysed for terrestrial cosmogenic nuclide (10Be) dating. Overlapping exposure ages indicate rapid evacuation of ice from much of the fjord at around 10.5 ka BP. Such substantial early Holocene retreat coincides with establishment of the local marine limit at c. 11 ka BP (Long et al. 2008). The new dates extend and confirm results from a tributary valley close to the fjord mouth that placed retreat from the present day coastline at c. 11.5 ka (Roberts et al. 2008). References: Roberts, D.H., Long, A.J., Schnabel, C., Freeman, S. and Simpson, M.J.R. 2008. The deglacial history of southeast sector of the Greenland Ice Sheet during the Last Glacial Maximum. Quaternary Science Reviews, 27, 1505-1516. Long, A.J., Roberts, R.H., Simpson, M.J.R., Dawson, S., Milne, G.A. and Huybrechts, P. 2008. Late Weichselian relative sea-level changes and ice sheet history in southeast Greenland. Earth and Planetary Science Letters, 272, 8-18.

  19. Incidence and risk factors of retreatment after three-monthly aflibercept therapy for exudative age-related macular degeneration

    Science.gov (United States)

    Kikushima, Wataru; Sakurada, Yoichi; Yoneyama, Seigo; Sugiyama, Atsushi; Tanabe, Naohiko; Kume, Atsuki; Mabuchi, Fumihiko; Iijima, Hiroyuki

    2017-01-01

    Though anti-vascular endothelial growth factor therapy has become the standard treatment for exudative age-related macular degeneration (AMD), retreatment after the initial loading injection is inevitable in most eyes with residual or recurrent exudative changes. In the present study, we studied 140 treatment naïve eyes with typical neovascular AMD (n = 71) or polypoidal choroidal vasculopathy (PCV) (n = 69) and investigated the incidence and risk factors of retreatment after 3-monthly intravitreal aflibercept injection for exudative AMD during the 12-month period. At 12 months, best-corrected visual acuity (BCVA) improved significantly from 0.45 ± 0.39 to 0.26 ± 0.33 (P = 4.1 × 10−11). Multiple regression analysis revealed that better baseline BCVA (P = 3.6 × 10−14) and thicker subfoveal choroidal thickness (P = 0.039) were associated with better BCVA at 12-months. Retreatment was required in 94 out of 140 (67.1%) eyes. Multivariate logistic regression analysis revealed that older age (P = 7.2 × 10−3) and T-allele of ARMS2 A69S (rs10490924) variants (P = 1.9 × 10−3) were associated with retreatment. Cox-regression analysis revealed that older age (P = 1.0 × 10−2) and T-allele of the ARMS2 gene (P = 6.0 × 10−3) were associated with retreatment-free period. The number of retreatment episodes was significantly different among the ARMS2 genotypes (P = 8.1 × 10−4). These findings might be helpful for physicians when considering the optimal treatment regimen for exudative AMD. PMID:28266609

  20. The cycle of instability: stress release and fissure flow as controls on gully head retreat

    Science.gov (United States)

    Collison, A. J. C.

    2001-01-01

    Gully head and wall retreat has commonly been attributed to fluvial scour and head collapse as a result of soil saturation, sapping or piping. The empirical evidence to substantiate these conceptual models is sparse, however, and often contradictory. This paper explores the hydrological and mechanical controls on gully head and wall stability by modelling the hydrology, stability and elastic deformation of a marl gully complex in Granada Province, south-east Spain. The hydrological and slope-stability simulations show that saturated conditions can be reached only where preferential fissure flow channels water from tension cracks into the base of the gully head, and that vertical or subvertical heads will be stable unless saturation is achieved. Owing to the high unsaturated strengths of marl measured in this research, failure in unsaturated conditions is possible only where the gully head wall is significantly undercut. Head retreat thus requires the formation of either a tension crack or an undercut hollow. Finite-element stress analysis of eroding slopes reveals a build up of shear stress at the gully head base, and a second stress anomaly just upslope of the head wall. Although tension cracks on gully heads have often been attributed to slope unloading, this research provides strong evidence that the so called sapping hollow commonly found in the gully headwall base is also a function of stress release. Although further research is needed, it seems possible that pop out failures in river channels may be caused by the same process. The hydrological analysis shows that, once a tension crack has developed, throughflow velocity in the gully headwall will increase by an order of magnitude, promoting piping and enlargement of this weakened area. It is, therefore, possible to envisage a cycle of gully expansion in which erosion, channel incision or human action unloads the slope below a gully head, leading to stress patterns that account for the tension crack and a

  1. Steps toward determination of the size and structure of the broad-line region in active galatic nuclei. 8: An intensive HST, IUE, and ground-based study of NGC 5548

    Science.gov (United States)

    Korista, K. T.; Alloin, D.; Barr, P.; Clavel, J.; Cohen, R. D.; Crenshaw, D. M.; Evans, I. N.; Horne, K.; Koratkar, A. P.; Kriss, G. A.

    1995-01-01

    We present the data and initial results from a combined Hubble Space Telescope (HST)/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988-1989. IUE spectra were obtained once every 2 days for a period of 74 days beginning on 1993 March 14. During the last 39 days of this campaign, spectroscopic observations were also made with the HST Faint Object Spectrograph (FOS) on a daily basis. Ground-based observations, consisting of 165 optical spectra and 77 photometric observations (both CCD imaging and aperture photometry), are reported for the period 1992 October-1993 September, although many of the data are concentrated around the time of the satellite-based program. These data constitute a fifth year of intensive optical monitoring of this galaxy. In this contribution we describe the acquisition and reduction of all of the satellite and ground-based data obtained in this program. We describe in detail various photometric problems with the FOS and explain how we identified and corrected for various anomalies.

  2. Discerning Robert Frost’s Life Philosophy from Some of His Poems--Roaming on the Margin of Retreat and Regress

    Institute of Scientific and Technical Information of China (English)

    余仕鹏; 刘丹丹; 温晓兰

    2014-01-01

    As a giant figure of American literature,Robert Frost has been receiving world-wide concerns and studies in literati.On retreat and regress,it intends to discern Robert Frost's life philosophy--“roaming on the margin of retreat and regress”from some of his poems from humanism approach.

  3. A comparative evaluation of efficacy of protaper universal rotary retreatment system for gutta-percha removal with or without a solvent

    Directory of Open Access Journals (Sweden)

    M Sita Ram Kumar

    2012-01-01

    Full Text Available Aim: The aim was to evaluate and compare the efficacy of ProTaper Universal rotary retreatment system with or without solvent and stainless steel hand files for endodontic filling removal from root canals and also to compare retreatment time for each system. Materials and Methods: Thirty extracted mandibular premolars with single straight canals were endodontically treated. Teeth were divided into three major groups, having 10 specimens each. Removal of obturating material in group 1 by stainless steel hand files with RC Solve, group 2 by ProTaper Universal retreatment instruments and group 3 by ProTaper Universal retreatment instruments along with RC solve was done. Retreatment was considered complete for all groups when no filling material was observed on the instruments. The retreatment time was recorded for each tooth. All specimens were grooved longitudinally in a buccolingual direction. The split halves were examined under a stereomicroscope and images were captured and analyzed. The remaining filling debris area ratios were considered for statistical analysis. Results: With ANOVA test, statistical analysis showed that there was statistically no significant difference regarding the amount of filling remnants between the groups (P < 0.05. Differences between the means of groups are statistically significant regarding the retreatment time. Conclusion: Irrespective of the technique used, all the specimens had some remnants on the root canal wall. ProTaper Universal retreatment system files alone proved to be faster than the other experimental groups.

  4. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    Directory of Open Access Journals (Sweden)

    P. Coupel

    2011-07-01

    Full Text Available A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA ocean during a year of exceptional ice retreat (August–September 2008. This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC and taxonomy (microscopy acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N to extreme high latitudes over the Alpha Ridge (86° N encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin.

    Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1–5 mg m−3 dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (<0.1 mg m−3 and algal assemblages were dominated by haptophytes and diatoms while higher biomasses (~0.4 mg m−3 related to a deep Subsurface Chlorophyll Maximum (SCM are associated to small-sized (nano and pico phytoplankton. The ice melting onset allows to point out three different zones over the open basin: (i the ice free condition characterized by deep and unproductive phytoplankton communities dominated by nanoplankton, (ii an extended (78°–83° N Active Melting Zone (AMZ where light penetration associated to the stratification start off and enough nutrient availability drives to the highest biomass and primary production due to both diatoms and large flagellates, (iii heavy ice conditions found north to 83° N allowing light limitation and consequently low biomass and primary production associated to pico

  5. Retreatment of failed regenerative endodontic of orthodontically treated immature permanent maxillary central incisor: a case report

    Directory of Open Access Journals (Sweden)

    Musaed Fahad Al-Tammami

    2017-02-01

    Full Text Available A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

  6. Impacts of Aerosols on the Retreat of the Sierra Nevada Glaciers in California

    Science.gov (United States)

    El-Askary, H. M.; Li, J.; Ta, T. N.; Jong, A.; Zhang, X.

    2015-12-01

    Natural dust aerosol is an active component of the climate system and plays multiple roles in physical climate and bio-geo-chemical exchanges between the atmosphere, land surface and ocean. Aerosol deposition on snow is amongst the different causes of glacier retreat around the world as well as the reduction of snow albedo. We have observed a long range transport of dust and pollution aerosols from China to the U.S. In this paper we compared summer and winter seasons glacier changes between 2000 and 2013, and how the dust aerosol change over this 13 years. Multiple images, acquired from Landsat-5 TM, Landsat-7 ETM+ and Landsat-8 OLI were used in the study. The change detection analysis was employed to identify the glacier changes for two seasons. The results suggest that the glacier decreased dramatically over 13 years in both seasons.

  7. Attempts to retreat from a dead-ended long capillary by backward swimming in Paramecium.

    Science.gov (United States)

    Kunita, Itsuki; Kuroda, Shigeru; Ohki, Kaito; Nakagaki, Toshiyuki

    2014-01-01

    We have observed how the ciliate Paramecium attempts to retreat from the dead-end of a long capillary that is too narrow for turning. After many trial-and-error episodes of short-term backward swimming (SBS), which is the conventional avoidance behavior exhibited in free swimming when an obstacle is faced, long-term backward swimming (LBS) that lasted five to ten times longer was developed. LBS may have a beneficial effect for complete withdrawal from the capillary space, although in our experiment it was impossible for the organism to do so due to the capillary length. In order to identify a physically possible mechanism for LBS, we propose model equations for the membrane potential of Hodgkin-Huxley type, which describe the control of ciliary movement. The physiological implications and physical mechanism of the development of LBS are discussed.

  8. Predicting Land-Ice Retreat and Sea-Level Rise with the Community Earth System Model

    Energy Technology Data Exchange (ETDEWEB)

    Lipscomb, William [Los Alamos National Laboratory

    2012-06-19

    Coastal stakeholders need defensible predictions of 21st century sea-level rise (SLR). IPCC assessments suggest 21st century SLR of {approx}0.5 m under aggressive emission scenarios. Semi-empirical models project SLR of {approx}1 m or more by 2100. Although some sea-level contributions are fairly well constrained by models, others are highly uncertain. Recent studies suggest a potential large contribution ({approx}0.5 m/century) from the marine-based West Antarctic Ice Sheet, linked to changes in Southern Ocean wind stress. To assess the likelihood of fast retreat of marine ice sheets, we need coupled ice-sheet/ocean models that do not yet exist (but are well under way). CESM is uniquely positioned to provide integrated, physics based sea-level predictions.

  9. [Endodontic re-treatment or apical surgery, is an evidence-based choice possible?].

    Science.gov (United States)

    de Lange, J

    2016-02-01

    Treatment of a recurrence after an initial endodontic treatment can consist of endodontic re-treatment or apical surgery. The literature reports comparable success rates for these two options. However, randomised controlled trials that are truly comparable to each other are unavailable as a result of which comparison and an informed choice are not really possible. In addition to the treatment outcome, consideration also has to be given to cost-effectiveness and other patient-related factors, such as pain, swelling and medication. Regarding these considerations, too, little reliable information can be found in the literature. Moreover, factors relating to insurance play an important role in the Netherlands, where only apical surgery is covered by the basic healthcare insurance. In conclusion, all of these factors should be carefully considered before proceeding to an individual treatment strategy.

  10. Retreatment of failed regenerative endodontic of orthodontically treated immature permanent maxillary central incisor: a case report.

    Science.gov (United States)

    Al-Tammami, Musaed Fahad; Al-Nazhan, Saad A

    2017-02-01

    A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

  11. Retreatment of failed regenerative endodontic of orthodontically treated immature permanent maxillary central incisor: a case report

    Science.gov (United States)

    Al-Tammami, Musaed Fahad

    2017-01-01

    A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation. PMID:28194367

  12. Late proterozoic and paleozoic tides, retreat of the moon, and rotation of the earth

    Science.gov (United States)

    Sonett, C.P.; Kvale, E.P.; Zakharian, A.; Chan, M.A.; Demko, T.M.

    1996-01-01

    The tidal rhythmites in the Proterozoic Big Cottonwood Formation (Utah, United States), the Neoproterozoic Elatina Formation of the Flinders Range (southern Australia), and the Lower Pennsylvanian Pottsville Formation (Alabama, United States) and Mansfield Formation (Indiana, United States) indicate that the rate of retreat of the lunar orbit is d??/dt k2 sin(2??) (where ?? is the Earth-moon radius vector, k2 is the tidal Love number, and ?? is the tidal lag angle) and that this rate has been approximately constant since the late Precambrian. When the contribution to tidal friction from the sun is taken into account, these data imply that the length of the terrestrial day 900 million years ago was -18 hours.

  13. Attempts to retreat from a dead-ended long capillary by backward swimming in Paramecium

    Directory of Open Access Journals (Sweden)

    Itsuki eKunita

    2014-06-01

    Full Text Available We have observed how the ciliate Paramecium attempts to retreat from the dead-end of a long capillary that is too narrow for turning. After many trial-and-error episodes of short-term backward swimming (SBS, which is the conventional avoidance behavior exhibited in free swimming when an obstacle is faced, long-term backward swimming (LBS that lasted five to ten times longer was developed. LBS may have a beneficial effect for complete withdrawal from the capillary space, although in our experiment it was impossible for the organism to do so due to the capillary length. In order to identify a physically possible mechanism for LBS, we propose model equations for the membrane potential of Hodgkin-Huxley type, which describe the control of ciliary movement. The physiological implications and physical mechanism of the development of LBS are discussed.

  14. Detailed ice loss pattern in the northern Antarctic Peninsula: widespread decline driven by ice front retreats

    Directory of Open Access Journals (Sweden)

    T. A. Scambos

    2014-06-01

    Full Text Available The northern Antarctic Peninsula (nAP, 3 a−1 and 24.9 ± 7.8 Gt a−1. This mass loss is compatible with recent gravimetric assessments, but it implies that almost all the gravimetry-inferred loss lies in the nAP sector. Mass loss is highest for eastern glaciers affected by major ice shelf collapses in 1995 and 2002, where twelve glaciers account for 60% of the total imbalance. However, losses at smaller rates occur throughout the nAP, and at high and low elevation, despite increased snow accumulation along the western coast and at high elevations. We interpret the widespread mass loss to be driven by decades of ice front retreats on both sides of the nAP, and by the propagation of kinematic waves triggered at the fronts into the interior.

  15. The Role of Regional Conferences in Research Resident Career Development: The California Psychiatry Research Resident Retreat.

    Science.gov (United States)

    Besterman, Aaron D; Williams, Jody K; Reus, Victor I; Pato, Michele T; Voglmaier, Susan M; Mathews, Carol A

    2017-04-01

    For psychiatry research resident career development, there is a recognized need for improved cross-institutional mentoring and networking opportunities. One method to address this need is via regional conferences, open to current and recently graduated research residents and their mentors. With this in mind, we developed the biennial California Psychiatry Research Resident Retreat (CPRRR) and collected feedback from participants to 1) Assess resident satisfaction, 2) Determine the utility of the retreat as a networking and mentorship tool, and 3) Identify areas for improvement. We gathered survey data from resident attendees at the two first CPRRRs. We analyzed the data to look for trends in satisfaction as well as areas that need improvement. Thirty-two residents from five California training programs attended the CPRRR in 2013 while 33 attended from six programs in 2015. The residents were from all years of training, but concentrated in their second and third years. Approximately 41% and 49% of the attendees were female and 53% and 39% had an MD/PhD in 2013 and 2015, respectively. Twenty-four and 32 residents provided anonymous feedback in 2013 and 2015, respectively. Mean feedback scores were very high (> 4/5) for overall satisfaction, peer- and faculty-networking, the keynote speaker and the flash talks for both years. Mean feedback scores for the ethics debates and mentoring sessions were somewhat lower (≤ 4/5), however, both showed significant improvement from 2013 to 2015. The CPRRRs appear to be an effective mechanism for providing psychiatry research residents with a meaningful cross-institutional opportunity for networking and mentorship. Feedback-driven changes to the CPRRRs improved participant satisfaction for several components of the conference. Future efforts will be aimed at broadening mentorship and networking opportunities, optimizing teaching approaches for research ethics, and considering different feedback-gathering approaches to allow for

  16. Faster Arctic Sea Ice Retreat in CMIP5 than in CMIP3 due to Volcanoes

    Science.gov (United States)

    Rosenblum, Erica; Eisenman, Ian

    2016-12-01

    The downward trend in Arctic sea ice extent is one of the most dramatic signals of climate change during recent decades. Comprehensive climate models have struggled to reproduce this, typically simulating a slower rate of sea ice retreat than has been observed. However, this bias has been widely noted to have decreased in models participating in the most recent phase of the Coupled Model Intercomparison Project (CMIP5) compared with the previous generation of models (CMIP3). Here we examine simulations from both CMIP3 and CMIP5. We find that simulated historical sea ice trends are influenced by volcanic forcing, which was included in all of the CMIP5 models but in only about half of the CMIP3 models. The volcanic forcing causes temporary simulated cooling in the 1980s and 1990s, which contributes to raising the simulated 1979-2013 global-mean surface temperature trends to values substantially larger than observed. We show that this warming bias is accompanied by an enhanced rate of Arctic sea ice retreat and hence a simulated sea ice trend that is closer to the observed value, which is consistent with previous findings of an approximately linear relationship between sea ice extent and global-mean surface temperature. We find that both generations of climate models simulate Arctic sea ice that is substantially less sensitive to global warming than has been observed. The results imply that the much of the difference in Arctic sea ice trends between CMIP3 and CMIP5 occurred due to the inclusion of volcanic forcing, rather than improved sea ice physics or model resolution.

  17. Cohort trends in premarital first births: what role for the retreat from marriage?

    Science.gov (United States)

    England, Paula; Wu, Lawrence L; Shafer, Emily Fitzgibbons

    2013-12-01

    We examine cohort trends in premarital first births for U.S. women born between 1920 and 1964. The rise in premarital first births is often argued to be a consequence of the retreat from marriage, with later ages at first marriage resulting in more years of exposure to the risk of a premarital first birth. However, cohort trends in premarital first births may also reflect trends in premarital sexual activity, premarital conceptions, and how premarital conceptions are resolved. We decompose observed cohort trends in premarital first births into components reflecting cohort trends in (1) the age-specific risk of a premarital conception taken to term; (2) the age-specific risk of first marriages not preceded by such a conception, which will influence women's years of exposure to the risk of a premarital conception; and (3) whether a premarital conception is resolved by entering a first marriage before the resulting first birth (a "shotgun marriage"). For women born between 1920-1924 and 1945-1949, increases in premarital first births were primarily attributable to increases in premarital conceptions. For women born between 1945-1949 and 1960-1964, increases in premarital first births were primarily attributable to declines in responding to premarital conceptions by marrying before the birth. Trends in premarital first births were affected only modestly by the retreat from marriages not preceded by conceptions-a finding that holds for both whites and blacks. These results cast doubt on hypotheses concerning "marriageable" men and instead suggest that increases in premarital first births resulted initially from increases in premarital sex and then later from decreases in responding to a conception by marrying before a first birth.

  18. Selective embolization of unruptured intracranial aneurysms is associated with low retreatment rate

    Energy Technology Data Exchange (ETDEWEB)

    Bandeira, Alexandra; Raphaeli, Guy [Erasme University Hospital, Department of Radiology, Neuroradiology Section, Brussels (Belgium); Erasme University Hospital, Interventional Neuroradiology Fellows, Brussels (Belgium); Baleriaux, Danielle [Erasme University Hospital, Department of Radiology, Neuroradiology Section, Brussels (Belgium); Bruneau, Michael; Witte, Olivier De [Erasme University Hospital, Neurosurgery, Brussels (Belgium); Lubicz, Boris [Erasme University Hospital, Department of Radiology, Neuroradiology Section, Brussels (Belgium); Hopital Erasme, Service de Radiologie, Brussels (Belgium)

    2010-02-15

    To report long-term imaging findings of 101 patients with 129 unruptured intracranial aneurysms (UIA) treated by embolization. A retrospective review of our prospectively maintained database identified all patients with an UIA treated by embolization with coils only and with a minimal 12-month imaging follow-up. The clinical charts, procedural data, and angiographic results were reviewed. Between March 2004 and June 2009, 101 patients with 129 UIA were identified (71 women/30 men, mean age = 51.4 years). Ninety-four aneurysms (73%) were large (10-25 mm), and 35 (27%) were small (<10 mm). Aneurysms mean size was 10.7 mm (median, 9 mm; range 3-22 mm); 87 UIA (67.5%) had a small neck (<4 mm or neck/sac ratio < 0.7), and 42 (32.5%) had a wide neck ({>=}4 mm or neck/sac ratio {>=} 0.7). Selective coiling with bare/coated coils was performed in 125 cases and four cases, respectively. The balloon-assisted technique was used in 47 cases (36.4%). Only one patient experienced a symptomatic complication (thromboembolism) and kept a slight hemiparesis. Immediate results included 77 complete occlusions (59.7%), 45 neck remnants (34.9%), and 7 incomplete occlusions (5.4%). Mean imaging follow-up of 32 months showed 104 stable occlusions (80.6%), 12 further thrombosis (9.3%), 7 major recanalizations (5.4%), and 6 minor recanalizations (4.7%). Retreatment was required in seven wide-necked and/or large aneurysms including four treated with coated coils. No bleeding occurred during follow-up. Selective embolization of UIA is associated with stable long-term anatomical results and low retreatment rate. (orig.)

  19. Future increases in Arctic precipitation linked to local evaporation and sea ice retreat

    Science.gov (United States)

    Bintanja, Richard; Selten, Frank

    2016-04-01

    Projected end-of-the-21st-century precipitation trends show an increase of over 50% in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate model output in standardised forcing simulations to quantify 21st-century trends in the Arctic moisture budget, revealing that the projected increase in Arctic precipitation (peaking in late fall and winter) is in fact due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree to enhanced moisture inflow from lower latitudes (maximum in late summer/fall). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea ice decline. As a result, the Arctic mean precipitation sensitivity (4.5% increase per degree temperature warming) is much larger than the global value (1.6 - 1.9%/K). The associated seasonally varying increase in Arctic precipitation will reinforce river discharge, enhance ice sheet mass balance and thereby affect global sea level, and may even impact global climate through Arctic Ocean freshening and subsequent modulations of the Atlantic Meridional Overturning Circulation. Bintanja, R. and F.M. Selten, 2014: Future increases in Arctic precipitation linked to local evaporation and sea ice retreat. Nature, 509, 479-482, doi:10.1038/nature13259.

  20. Stability assessment of rock surrounding an I-beam supported retreating roadway

    Institute of Scientific and Technical Information of China (English)

    严红; 张吉雄; 李林玥; 冯锐敏

    2015-01-01

    The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the surrounding rock, a mechanical model was developed for the stability of the roadway support and surrounding rock. Analysis of the bearing capacity of the roof back-wall guard-board and modelling of the equations for the maximum deflection and the maximum compressive stress of the top and side beams of the I-shaped steel support were undertaken. Simultaneously, the model was used to calculate and analyse the stability of the top and side beams of the I-shaped steel support structure and analyse the criteria for their stability. The results provide a reliable theoretical basis for the judgment of the stability of the surrounding rock and support structure. The theoretical evaluation results are consistent with field data. Finally, the key support parameters of the top and side beams of the I-shaped steel support structure and the variation of the maximum deflection and the maximum compressive stress as affected by the influence of the guard-board length were investigated. It is concluded that, as the back-board length increases, the maximum compressive stress in the top beam of the I-shaped steel support increases while the compressive stress in the side beam decreases. The results show that the accuracy of judgment of the stability of a supported retreating roadway is improved, providing guidance for the design of such typical I-shaped steel support and back-board structures.

  1. Geomorphic response of rivers to glacial retreat and increasing peak flows downstream from Mount Rainier, Washington

    Science.gov (United States)

    Czuba, J. A.; Barnas, C. R.; Magirl, C. S.; Voss, F. D.

    2010-12-01

    On Mount Rainier, Washington, the National Park Service has documented widespread aggradation of as much as 10 m since the early 20th century, of rivers draining the glaciated stratovolcano. This rapid sedimentation appears to be related to glacial retreat and also may be a function of the increased magnitude and timing of peak flows that mobilize and transport sediment. We are conducting an assessment of the Puget Lowland rivers that drain Mount Rainier, 25-100 km downstream from the park boundary, to document the geomorphic response of the downstream reaches given the widespread aggradation upstream. These downstream reaches provide critical aquatic habitat for spawning and rearing of several species of salmonids, including endangered Chinook salmon and steelhead. Fluvial sedimentation can have both deleterious and beneficial effects on aquatic habitat depending on sediment particle size, river slope and width, and river management. To date, our work shows sedimentation of as much as 2 m between 1984 and 2009 in these lowland rivers. Aggradation rates that were calculated by comparing channel change at 156 cross sections, ranged between 4.8 and 9.1 cm/yr in reaches where rivers exit the mountain front and enter the lowland. Analysis of streamflow-gaging station data from throughout the watersheds draining Mount Rainier show rapid incision and aggradation, suggesting pulses of coarse-grained bedload may be moving down the mountainous rivers as kinetic waves. Preliminary results, however, seem to indicate that the rivers in the Puget Lowland have not yet experienced significant widespread sedimentation directly related to glacial retreat. Estimating the time of arrival of mobilized alluvium is a critical need for resource managers given the potential effects of sedimentation on river flood-conveyance capacity, fish habitat, and estuarine wetlands.

  2. Evaluating the effectiveness of enhancing resilience in human service professionals using a retreat-based Mindfulness with Metta Training Program: a randomised control trial.

    Science.gov (United States)

    Pidgeon, Aileen M; Ford, Lucas; Klaassen, Frances

    2014-01-01

    This paper explores the feasibility of a brief Mindfulness with Metta Training Program (MMTP), targeting the enhancement of mindfulness and self-compassion in a retreat format, as a means of increasing resilience in human services professionals. In this randomised control trial, 44 human services professionals were randomly allocated either to a MMTP retreat group or to a control group. Following the MMTP intervention, no significant differences between the retreat and control groups were found on resilience, mindfulness and self-compassion variables. However, significant improvements were observed over time for the retreat group for mindfulness and self-compassion at one and four months and for resilience at four-months post MMTP intervention. The results of this pilot study show that MMTP in a retreat format is a promising method of increasing resilience, mindfulness and self-compassion in human services professionals.

  3. Hypofractionated external beam radiotherapy as retreatment for symptomatic non-small-cell lung carcinoma: an effective treatment?

    NARCIS (Netherlands)

    Kramer, G.W.P.M.; Gans, S.; Ullmann, E.F.; Meerbeeck, J.P. van; Legrand, C.; Leer, J.W.H.

    2004-01-01

    PURPOSE: To evaluate prospectively the efficacy, toxicity, and duration of the palliative effect of retreatment with external beam radiotherapy in symptomatic patients with recurrent non-small-cell lung cancer. METHODS AND MATERIALS: Twenty-eight symptomatic patients with local recurrence of

  4. Creating a specialist protein resource network: a meeting report for the protein bioinformatics and community resources retreat

    DEFF Research Database (Denmark)

    Babbitt, Patricia C.; Bagos, Pantelis G.; Bairoch, Amos

    2015-01-01

    During 11–12 August 2014, a Protein Bioinformatics and Community Resources Retreat was held at the Wellcome Trust Genome Campus in Hinxton, UK. This meeting brought together the principal investigators of several specialized protein resources (such as CAZy, TCDB and MEROPS) as well as those from ...

  5. Differences in the clinical-epidemiological profile between new cases of tuberculosis and retreatment cases after default

    Directory of Open Access Journals (Sweden)

    Aylana de Souza Belchior

    Full Text Available Abstract OBJECTIVE To identify the socioeconomic and clinical-epidemiological factors related to tuberculosis in new cases and retreatment cases. METHOD Comparative study with 126 patients, of which 42 were retreatment cases after default attended in a reference center, and 84 were new cases completing the first treatment and treated in Basic Health Units. The collection of primary data was through interview, and of secondary data by records of the Notifiable Diseases Information System. Comparative analysis between the two groups. RESULTS The new cases differ from retreatment cases regarding educational level. The clinical-epidemiological profile shows a significant difference in relation to performance of the tuberculin skin test, and the HIV test result (positive in favor of new cases. In relation to performance of sputum culture and the result (positive of the first sputum smear of the first and second samples, in favor of retreatment cases. CONCLUSION The two groups are significantly different in clinical and epidemiological characteristics that show the access to exams.

  6. In vitro evaluation of the ability of three apex locators to determine the working length during retreatment.

    Science.gov (United States)

    Goldberg, Fernando; Marroquín, Benjamín Briseño; Frajlich, Santiago; Dreyer, Cristian

    2005-09-01

    The purpose of this in vitro study was to evaluate the accuracy of three apex locators in determining the working length during the retreatment process. Twenty extracted single-rooted human teeth with mature apices were used in this study. The root canal length of each tooth was measured placing a #15 file until the tip was visible at the apical foramen. The direct visual measurement was reduced by 0.5 mm and recorded. The root canals were instrumented and filled to the direct visual measurement using lateral compaction technique. After 7 days the teeth were retreated using three apex locators: ProPex, NovApex, and Root ZX, for determining the retreatment working length. Afterward, comparison between the visual working length and the retreatment working length were made. ProPex, NovApex, and Root ZX were accurate within 0.5 mm 80, 85, and 95% of the time, and within 1 mm 95, 95, and 100%, respectively. No significant differences were detected between the three apex locators (p > 0.05).

  7. Creating a specialist protein resource network: a meeting report for the protein bioinformatics and community resources retreat

    DEFF Research Database (Denmark)

    Babbitt, Patricia C.; Bagos, Pantelis G.; Bairoch, Amos;

    2015-01-01

    protein databases from the large Bioinformatics centres (including UniProt and RefSeq). The retreat was divided into five sessions: (1) key challenges, (2) the databases represented, (3) best practices for maintenance and curation, (4) information flow to and from large data centers and (5) communication...

  8. A new approach to river bank retreat and advance in 2D numerical models of fluvial morphodynamics

    NARCIS (Netherlands)

    Spruyt, A.; Mosselman, E.; Jagers, B.

    2011-01-01

    River bank retreat and advance are modes of morphological evolution in addition to bed level changes and changes in bed sediment composition. They produce planform changes such as width adjustment and meander bend migration. However, their reproduction in a 2D numerical model still remains a challen

  9. Creating a specialist protein resource network: a meeting report for the protein bioinformatics and community resources retreat

    NARCIS (Netherlands)

    Babbitt, P.C.; Bagos, P.G.; Bairoch, A.; Bateman, A.; Chatonnet, A.; Chen, M.J.; Craik, D.J.; Finn, R.D.; Gloriam, D.; Haft, D.H.; Henrissat, B.; Holliday, G.L.; Isberg, V.; Kaas, Q.; Landsman, D.; Lenfant, N.; Manning, G.; Nagano, N.; Srinivasan, N.; O'Donovan, C.; Pruitt, K.D.; Sowdhamini, R.; Rawlings, N.D.; Saier, M.H., Jr.; Sharman, J.L.; Spedding, M.; Tsirigos, K.D.; Vastermark, A.; Vriend, G.

    2015-01-01

    During 11-12 August 2014, a Protein Bioinformatics and Community Resources Retreat was held at the Wellcome Trust Genome Campus in Hinxton, UK. This meeting brought together the principal investigators of several specialized protein resources (such as CAZy, TCDB and MEROPS) as well as those from pro

  10. Glacier retreat and associated sediment dynamics in proglacial areas: a case study from the Silvretta Alps, Austria

    Science.gov (United States)

    Felbauer, Lucia; Pöppl, Ronald

    2016-04-01

    Global warming results in an ongoing retreat of glaciers in the Alps, leaving behind large amounts of easily erodible sediments. In addition, the debuttressing of rock-walls and the decay of permafrost in the high mountain regions facilitates mass movements of potential disastrous consequences, such as rock falls, landslides and debris flows. Therefore, it is highly important to quantify the amount of sediments that are supplied from the different compartments and to investigate how glacial retreat influences sediment dynamics in proglacial areas. In the presented work glacier retreat and associated sediment dynamics were investigated in the Kromer valley (Silvretta Alps, Austria) by analyzing remote sensing data. Glacial retreat from the period of 1950 to 2012 was documented by interpreting aerial photographs. By digitizing the different stages of the glaciers for six time frames, changes in glacier area and length were mapped and quantified. In order to identify, characterize and quantify sediment dynamics in the proglacial areas a high resolution DEM of difference (DoD) between 2007 and 2012 was created and analyzed, further differentiating between different zones (e.g. valley bottom, hillslope) and types of geomorphic processes (e.g. fluvial, gravitational). First results will be presented at the EGU General Assembly 2016.

  11. Peeking Under the Ice… Literally: Records of Arctic Climate Change from Radiocarbon Dating Moss Emerging from Beneath Retreating Glaciers

    Science.gov (United States)

    Briner, J. P.; Schweinsberg, A.; Miller, G. H.; Lifton, N. A.; Beel, C. R.; Bennike, O.

    2014-12-01

    Dramatic changes are taking place throughout the Arctic. Many glaciers have already melted away completely, and most others are well on their way as rising snowline elevations promise continued glacier retreat. Emerging from beneath retreating glacier margins is a landscape rich in information about past climate and glacier changes. Within newly exposed bedrock is an inventory of cosmogenic nuclides that archive past ice cover timing and duration. Lake basins re-appearing due to retreating ice preserve sediment archives that tell of cooling climate and advancing ice. And ancient surfaces vegetated with tundra communities that have long been entombed beneath frozen-bedded ice caps are now being revealed for the first time in millennia. This presentation will focus on the climate and glacier record derived from radiocarbon dating of in situ moss recently exhumed from retreating local ice cap margins on western Greenland. Dozens of radiocarbon ages from moss group into several distinct modes, which are interpreted as discrete times of persistent summer cooling and resultant glacier expansion. The data reveal a pattern of glacier expansion beginning ~5000 years ago, followed by periods of glacier growth around 3500 and 1500 years ago. Because these times of glacier expansion are recorded at many sites in western Greenland and elsewhere in the Arctic, they are interpreted as times of step-wise summer cooling events during the Holocene. These non-linear climate changes may be a result of feedbacks that amplify linear insolation forcing of Holocene climate. In addition to these insights into the Arctic climate system, the antiquity of many radiocarbon ages of ice-killed moss indicate that many arctic surfaces are being re-exposed for the first time in millennia due to retreating ice, emphasizing the unprecedented nature of current summer warming.

  12. The landslide response of alpine basins to post-Little Ice Age glacial thinning and retreat in southwestern British Columbia

    Science.gov (United States)

    Holm, Kris; Bovis, Michael; Jakob, Matthias

    2004-02-01

    The role of post-Little Ice Age (LIA) Neoglacial retreat on landslide activity is investigated in 19 alpine basins along the upper Lillooet River Valley, British Columbia. We examine how Neoglacial scouring and glacial recession have modified hillslope form and slope stability, and construct a decision-making flowchart to identify landslide hazards associated with glacial retreat. This work is based on field mapping, GIS analysis, statistical associations between landslides and terrain attributes, and a comparison between Neoglaciated and non-Neoglaciated terrain within each basin. The bedrock landslide response to glacial retreat varies appreciably according to lithology and the extent of glacial scour below the LIA trimline. Valleys carved in weak Quaternary volcanics show significant erosional oversteepening and contain deep-seated slope movement features, active rock fall, rock slides, and rock avalanches near glacial trimlines. Basins in stronger granitic rock rarely show increased bedrock instability resulting from post-LIA retreat, except for shallow-seated rock slides along some trimlines and failures on previously unstable slopes. In surficial materials, landslides associated with post-LIA retreat originate in till or colluvium, as debris slides or debris avalanches, and are concentrated along lateral moraines or glacial trimlines. Significant spatial association was also observed between recent catastrophic failures, gravitational slope deformation, and slopes that were oversteepened then debuttressed by glacial erosion. Eight out of nine catastrophic rock slope failures occurred just above glacial trimlines and all occurred in areas with a previous history of deep-seated gravitational slope movement, implying that this type of deformation is a precursor to catastrophic detachment.

  13. Correlation of the asymmetrical retreat of the south polar cap and the polar layered terrain on Mars

    Science.gov (United States)

    Narumi, Y.; Iwasaki, K.

    2005-08-01

    During the southern springtime, the south polar cap retreats more rapidly in the polar region between longitudes 150W and 300W, compared with the other part of the southern polar region. The reason for this rapid retreat has remained enigmatic for a long time. Recently, Colaprete et al. (2005) proposed that the asymmetrical behavior of the south polar cap is caused by topographic forcing of atmospheric dynamics by the large basins, Argyre and Hellas. These results calculated by the Mars General Circulation Model (MGCM) may be correct on the large-scale phenomena of Mars. However, we would like to point out that this region of rapid retreat is almost coincident with the extent of the southern polar layered terrain, and propose that the polar layered terrain would play some distinct role in the asymmetrical retreat of the south polar cap. The north and south polar layered terrains are characterized by about 3 km of relief and are believed to be composed primarily of water ice mixed with dust. Because of the abundant amount of water ice, the thermal inertia of the polar layered terrain may be higher than the usual surface soil on Mars. Our preliminary model calculation shows that a higher value of thermal inertia results in less precipitation of the surface carbon dioxide ice. We expect that a higher value of thermal inertia for the polar layered terrain could explain the asymmetric retreat of the south polar cap, with its reduced quantity and delayed carbon dioxide ice deposit during winter, and earlier evaporation of ice in the southern springtime.

  14. Development and application of mechanical calculation and drawing software for conducting wire and ground wire of power transmission line%送电线路导地线力学计算绘图软件的开发与应用

    Institute of Scientific and Technical Information of China (English)

    梁世党

    2012-01-01

      以开发“送电线路导地线力学计算绘图”软件为例,介绍了如何在Excel 2007中利用Visual Basic语言开发一个能快速绘制各种设计气象条件、不同导地线型号的送电线路导地线应力弧垂计算及绘图的应用程序,供工程设计人员在Excel 2007二次开发中作为参考,从而提高绘图效率。%  Taking the development of mechanical calculation and drawing software for conducting wire and ground wire of power transmission line as example, the author presented how to use Excel 2007 and Visual Basic language to develop an application software which permits rapid stress sag calculation and drawing for different types of con⁃ducting wire and ground wire of power transmission line under various meteorological conditions, aiming to provide reference for secondary development of Excel 2007 and higher drawing efficiency.

  15. Characterizing the atomic mass surface beyond the proton drip line via a-decay measurements of the s1/2 ground state of 165Re and the h11/2 isomer in 161Ta

    CERN Document Server

    O'Donnell, D; Scholey, C; Bianco, L; Capponi, L; Carroll, R J; Darby, I G; Donosa, L; Drummond, M; Ertugral, F; Greenlees, P T; Grahn, T; Hauschild, K; Herzan, A; Jakobsson, U; Jones, P; Joss, D T; Julin, R; Juutinen, S; Ketelhut, S; Labiche, M; Leino, M; Lopez-Martens, A; Mullholland, K; Nieminen, P; Peura, P; Rahkila, P; Rinta-Antila, S; Ruotsalainen, P; Sandzelius, M; Saren, J; Saygi, B; Simpson, J; Sorri, J; Thornthwaite, A; Uusitalo, J; 10.1103/PhysRevC.86.064315

    2012-01-01

    The a-decay chains originating from the s1/2 and h11/2 states in 173Au have been investigated following fusion-evaporation reactions. Four generations of a radioactivities have been correlated with 173Aum leading to a measurement of the a decay of 161Tam. It has been found that the known a decay of 161Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt g rays feeding the ground state of 173Au. This prompt radiation was used to aid the study of the a-decay chain originating from the s1/2 state in 173Au. Three generations of a decays have been correlated with this state leading to the observation of a previously unreported activity which is assigned as the decay of 165Reg. This work also reports the excitation energy of an a-decaying isomer in 161Ta and the Q-value of the decay of 161Tag.

  16. Comprehensive Analysis of Lightning Performance of Overhead Power Distribution Line with Varied Ground Obliquity%不同地形条件下架空配电线路的防雷分析

    Institute of Scientific and Technical Information of China (English)

    刘靖; 刘明光; 屈志坚; 刘铁

    2011-01-01

    In order to take lightning problem into consideration comprehensively, we introduced a new model for calculating the lightning outage rate of overhead power distribution line due to direct and indirect lightning strokes. By establishing an improved EGM model of overhead distribution line based on striking distance theory, combining with probability density function of lightning current, we solved the attract range of overhead line, which possesses a nonlinear relationship with line height for different district. Taking the Rusck's formula into consideration, basing on Generalized Integral method, we put forward a new arithmetic for calculating the lightning outage rate which includes indirect lightning. By calculation of two real 10 kV power distribution line, the new method is practical and accurate. The results show that indirect strokes are the main cause of lightning trip out, and for analyzing the lightning performance of overhead power distribution lines, the indirect lightning must be taken into consideration.%雷电活动直接影响到架空电力线路的安全稳定运行,为全面分析架空配电线路的雷害问题,提出了一种计入地形条件影响的分析新方法.先基于雷电的击距理论建立架空配电线路的引雷模型,结合雷电流的概率密度函数,求出了线路在不同高度和不同地形条件下的引雷范围与线路高度呈非线性关系;在确定线路引雷范围的基础上,分别计算了我国不同地域的架空线路直接雷击跳闸率;在对Rusck感应雷过电压研究成果分析的基础上,利用广义积分法得出了不同地形和地域的感应雷击跳闸率计算公式,而且架空配电线路中感应雷击跳闸次数占总雷击跳闸次数能达到83%,在架空线路的防雷分析中应该计入感应雷击的影响.2条10 kV架空线路算例与实际运行情况的对比验证了该计算方法的正确性.

  17. 零序电流比例增量法在小电流接地故障选线中的应用%Application of the zero sequence current incremental ratio method in small current grounding fault line identification

    Institute of Scientific and Technical Information of China (English)

    王新超; 张玉海

    2011-01-01

    通过对小电流接地系统电路特点的深入研究发现,故障后在各条支路上流动的零序电容电流只决定于系统的零序电压与支路的对地电容,而不决定于故障发生在哪条支路上,且故障发生前后的支路对地电容几乎不变.非故障支路上流动的是零序电容电流,故障支路上流动着的是零序电容电流与接地电流的叠加.正是基于这一分析结果提出了一种零序电流比例增量法,定义了基准零序电流比例系数序列和参考基准电流分度系数等中间参量.其工作特点是可以剥离各支路的零序电容电流,并通过比较剥离后各支路增量的最大者,即故障支路.进一步的仿真表明该法稳定可靠,具有良好的适应能力.该法对其他判别法提高判别精度也有帮助.%Intensive studying on the characteristics of small current grounding system circuit finds that the zero sequence capacitive current in each powerline depends merely on the system's zero-sequence voltage and powerline-to-ground capacitances when a single-phase grounding failure happens, and does not depend on that the failure occurrs in which powerline, and the powerline-to-ground capacitances are almost unchanged before or after the failure. Non-fault powerline currents are zero sequence capacitive currents, but fault powerline current is the zero sequence capacitance current plus the grounding current. Based on the results of this analysis a zero sequence current proportion incremental method is given, which defines some medium-parameters such as the zero sequence current ratio standard coefficient array and reference current gauge coefficient. Characteristics of the method is that zero-sequence capacitive currents are stripped, and the maximum increment of the powerline is found, which is the fault one. Further simulations show that the method is stable and reliable, with good adaptability. The method can also improve identification accuracy of other

  18. Ground water and energy

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    This national workshop on ground water and energy was conceived by the US Department of Energy's Office of Environmental Assessments. Generally, OEA needed to know what data are available on ground water, what information is still needed, and how DOE can best utilize what has already been learned. The workshop focussed on three areas: (1) ground water supply; (2) conflicts and barriers to ground water use; and (3) alternatives or solutions to the various issues relating to ground water. (ACR)

  19. Microwave transmission-line impedance data

    CERN Document Server

    Gunston, M A R

    1996-01-01

    A compendium of data for computing the characteristic impedance of transmission lines based on physical dimensions. Covers both conventional structures and unusual geometries, including coaxial, eccentric and elliptic coaxial, twin-wire, wire-above-ground, microstrip and derivatives, stripline, slabline and trough line. Also details numerous configurations of coupled lines.

  20. 49 CFR 192.375 - Service lines: Plastic.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the...

  1. Measure Lines

    Science.gov (United States)

    Crissman, Sally

    2011-01-01

    One tool for enhancing students' work with data in the science classroom is the measure line. As a coteacher and curriculum developer for The Inquiry Project, the author has seen how measure lines--a number line in which the numbers refer to units of measure--help students not only represent data but also analyze it in ways that generate…

  2. Analysis of retreated medicine in dispensary for outpatients%门诊药房退药情况及原因分析

    Institute of Scientific and Technical Information of China (English)

    雷国强

    2011-01-01

    Objective: To analyze the retreated medicine situation in dispensary for outpatients in our hospital, so as to provide references for the reduction and standardization of retreated medicine. Methods: The retreated medicine datas in dispensary for outpatients from Jun to Dec in 2010 in our hospital were analyzed. Results: The retreated medicine in dispensary for outpatients was mainly resulted from the duty of doctors and the adverse drug reaction. The variety of retreated medicine was priority to antibiotic medicines; the retreated medicine occurred frequently in department of internal medicine.Conclusion: It should be strengthen the rational use of drugs, and pay attention to the guidance of adverse drug reaction,as to reduce the occurrence of retreated medicine.%目的:分析门诊退药情况,为减少和规范退药提供参考.方法:对我院门诊药房2010年6月~12月的患者退药情况进行统计分析.结果:门诊药房退药的主要原因为医师的责任和药物不良反应;退药品种以抗菌素为主;内科发生退药情况较频繁.结论:应加强合理用药指导,重视药品不良反应,进一步减少退药的发生.

  3. Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

    Science.gov (United States)

    Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

    2014-01-01

    It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

  4. Peptide receptor radionuclide therapy (PRRT): clinical significance of re-treatment?

    Energy Technology Data Exchange (ETDEWEB)

    Virgolini, Irene [Medical University Innsbruck, Department of Nuclear Medicine, Innsbruck (Austria); Collaboration: The Innsbruck Team

    2015-12-15

    PRRT appears to be the most effective therapeutic option in the management of inoperable or metastasized NET patients with limited side effects if dose limits are respected. In patients with relapse after a first treatment period with {sup 90}Y-DOTATOC, multiple re-treatment cycles with {sup 177}Lu-DOTATATE are feasible, safe and efficacious. Quantitative imaging by dosimetry adds to formulate personalized and evidence-based treatment protocols. However, despite the large body of evidence regarding efficacy and safety of PRRT, the absence of prospective randomized controlled trials questions the utility of PRRT in the community. Furthermore, the growing number of pharmacological or liver-directed therapeutic options competes with the confusion based on the variety of somatostatin analogues to determine the optimal choice and sequencing of PRRT in the individual patient. However, the efficacy of PRRT should not be questioned rather than it should be explored as to when PRRT might be optimally applied in the sequence of available therapy modalities. The results of the present study by the Italian group [5] emphasizes that radiopharmaceuticals are still underused. Despite the huge potential of PRRT the non-availability of PRRT in many countries still limits its widespread use. After acquiring the exclusive rights for {sup 177}Lu-DOTATATE with granted orphan designation, the company Advanced Accelerator Applications (AAA) is currently running a phase III study comparing treatment with {sup 177}Lu-DOTATATE to Octreotide LAR in patients with inoperable, progressive, somatostatin receptor-positive, midgut carcinoid tumours with the aim of registering the radiopharmaceutical under the commercial name of Lutathera. Together with orphan designation also to other somatostatin-based radiopharmaceuticals, such as {sup 90}Y-DOTATOC, {sup 177}Lu-DOTATOC and the {sup 68}Ga-labelled somatostatin antagonist OPS202, these developments promote the advancement of PRRT and PET imaging

  5. Beryllium-10 dating the last retreat of the Norwegian Channel Ice Stream at Utsira, western Norway

    Science.gov (United States)

    Briner, J. P.; Goehring, B. M.; Svendsen, J. I.; Mangerud, J.

    2016-12-01

    Knowing the age of the Last Glacial Maximum (LGM) extent of ice sheets is fundamental to ice age theory, but methods available for constraining maximum ice extent during the LGM are limited. Cosmogenic-nuclide exposure dating (e.g., 10Be dating) has emerged in the past two decades as a useful tool for dating LGM terminal moraine boulders. Cosmogenic-nuclide exposure dating has allowed many additional chronologies of LGM terminal moraines to arise from locations otherwise difficult to date. In some cases, however, cosmogenic-nuclide exposure ages might be skewed towards being too old due to the deep accumulation of 10Be from muon production. Svendsen et al. (2015, QSR v. 107, 231-242) used 10Be dating of erratic boulders on the island of Utsira to constrain the initial retreat of the Norwegian Channel Ice Stream (a major artery of the southern Scandinavian Ice Sheet) from its maximum LGM extent. The 10Be chronology, indicating retreat of the outer ice stream 20.2 ka, is at odds with radiocarbon constraints indicating that ice sheet recession initiated 18.5 ka. Commonly discussed factors such as uncertainty in the 10Be production rate, isotopic inheritance from neutron-produced 10Be, or problematic radiocarbon ages do not satisfactorily explain the disagreement. Although inheritance affects the 10Be age of some erratics, and one bedrock sample from the island has obvious inheritance, the strong cluster of 10Be ages from Utsira, which are identical in age to erratics from a nearby island, is not the typical age pattern reflecting inheritance. We attempt to reconcile the age offset by suggesting that all of the 10Be ages are influenced by the deep accumulation of muon-produced 10Be, making them too old. Using the latest knowledge in production of 10Be from muons in the Earth's crust, we show that muogenic 10Be is significant at depths of 5-10 m. In ice sheet distal landscapes, where there is commonly >100,000 years of exposure between glacial overriding events (like

  6. Late Burdigalian sea retreat from the North Alpine Foreland Basin: new magnetostratigraphic age constraints

    Science.gov (United States)

    Sant, K.; Kirscher, U.; Reichenbacher, B.; Pippèrr, M.; Jung, D.; Doppler, G.; Krijgsman, W.

    2017-05-01

    Accurate reconstruction of the final sea retreat from the North Alpine Foreland Basin (NAFB) during the Burdigalian (Early Miocene) is hampered by a lack of reliable age constraints. In this high resolution magnetostratigraphic study we try to solve a significant age bias for the onset of the Upper Freshwater Molasse (OSM) deposition in the neighboring S-German and Swiss Molasse Basins. We measured > 550 samples from eleven drill cores covering the transition from marine to brackish to freshwater environments in the S-German Molasse Basin. Based on combined bio-, litho- and magnetostratigraphic constraints, the composite magnetostratigraphic pattern of these cores provides two reasonable age correlation options (model 1 and 2). In model 1, the base of the brackish succession lies within Chron C5Cr ( 16.7-17.2 Ma), and the onset of OSM deposition has an age of 16.5 Ma. Correlation model 2 suggests the transition to brackish conditions to be within C5Dr.1r ( 17.7-17.5 Ma), and yields an age around 16.7 Ma for the shift to the OSM. Most importantly, both models confirm a much younger age for the OSM base in the study area than previously suggested. Our results demonstrate a possible coincidence of the last transgressive phase (Kirchberg Fm) with the Miocene Climatic Optimum (model 1), or with the onset of this global warming event (model 2). In contrast, the final retreat of the sea from the study area is apparently not controlled by climate change. Supplementary material B. Profiles of the eleven studied drill cores including lithologies, all magnetostratigraphic data (inclinations), interpreted polarity pattern (this study and Reichenbacher et al., 2013) and magnetic susceptibility (this study). Legend for graphs on page 1. Samples without a stable direction above 200 °C or 20 mT are depicted as +-signs and plotted at 0° inclination. The interpreted normal (black), reversed (white) and uncertain (grey) polarity zones in the polarity columns are based on at least

  7. A millennial-scale record of tidewater glacier advance and retreat, SW Greenland.

    Science.gov (United States)

    Pearce, Danni; Mair, Doug; Rea, Brice; Schofield, Ed; Lea, James; Barr, Iestyn; Kamenos, Nick; Schoenrock, Kate

    2017-04-01

    Tidewater glaciers (TWGs) exert a major control on the short- and long-term mass balance of the Greenland Ice Sheet (GrIS) and have experienced widespread retreat over the last century. However, in many cases inferences on their dynamics, prior to this, are poorly constrained due to a lack of observations and paucity of mapped or mappable deglacial geomorphology. Especially lacking is evidence associated with TWG advance during the Little Ice Age (LIA, AD c. 1300 to 1850). Such data are crucial for numerical model calibration and validation in order to more confidently forward model ice sheet dynamics and projection future sea-level rise. Therefore, empirical data constraints from the palaeo-record, that span such timescales (decadal to millennial), are essential. Kangiata Nunaata Sermia (KNS) is the most dynamic TWG in SW Greenland, located c. 100 km inland from Nuuk, at the head of Godthabsfjord. KNS has received considerable research attention over the last decade but glacial geomorphological and numerical dating investigations have been limited. However, the adjacent topography and geomorphology presents a unique opportunity to reconstruct the advance and retreat dynamics over the LIA. We present detailed glacial geomorphological mapping for KNS, which followed a morphostratigraphic approach, using a combination of aerial photos, Landsat, a DEM and field mapping. This identified a three landsystems, which are associated with the LIA, pre-LIA and neoglacial. From the mapping inferences on rapid changes in meltwater routing have been inferred. When KNS reached its LIA maximum (c. 1761), the calving front was c. >22 km further along the fjord than present and a number of ice-dammed lakes were formed. We present new 14C dating from peat underlying lake sediments associated with an ice-dammed lake and buried palaeosols resulting from meltwater re-routing over topographic spillways. The ages support an early and rapid LIA advance phase, with advance rates being

  8. Kame deltas provide evidence for a new glacial lake and suggest early glacial retreat from central Lower Michigan, USA

    Science.gov (United States)

    Schaetzl, Randall J.; Lepper, Kenneth; Thomas, Sarah E.; Grove, Leslie; Treiber, Emma; Farmer, Alison; Fillmore, Austin; Lee, Jordan; Dickerson, Bethany; Alme, Kayleigh

    2017-03-01

    In association with an undergraduate Honors Seminar at Michigan State University, we studied two small kame deltas in north-central Lower Michigan. These recently identified deltas provide clear evidence for a previously unknown proglacial lake (Glacial Lake Roscommon) in this large basin located in an interlobate upland. Our first goal was to document and characterize the geomorphology of these deltas. Because both deltas are tied to ice-contact ridges that mark the former position of the retreating ice margin within the lake, our second goal was to establish the age of one of the deltas, thereby constraining the timing of ice retreat in this part of Michigan, for which little information currently exists. Both deltas are composed of well-sorted fine and medium sands with little gravel, and have broad, nearly flat surfaces and comparatively steep fronts. Samples taken from the upper 1.5 m of the deltas show little spatial variation in texture, aside from a general fining toward their outer margins. Gullies on the outer margins of both deltas probably postdate the formation of the deltas proper; we suggest that they formed by runoff during a permafrost period, subsequent to lake drawdown. We named the ice lobe that once covered this area the Mackinac Lobe, because it had likely advanced into the region across the Mackinac Straits area. Five of six optically stimulated luminescence (OSL) ages from one of the deltas had minimal scatter and were within ± 1000 years of one another, with a mean age of 23.1 ± 0.4 ka. These ages suggest that the Mackinac Lobe had started to retreat from the region considerably earlier than previously thought, even while ice was near its maximum extent in Illinois and Indiana, and the remainder of Michigan was ice-covered. This early retreat, which appears to coincide with a short-lived warm period indicated from the Greenland ice core, formed an "opening" that was at least occasionally flooded. Thick and deep, fine-textured deposits

  9. Role of ground water in geomorphology, geology, and paleoclimate of the Southern High Plains, USA.

    Science.gov (United States)

    Wood, Warren W

    2002-01-01

    Study of ground water in the Southern High Plains is central to an understanding of the geomorphology, deposition of economic minerals, and climate change record in the area. Ground water has controlled the course of the Canadian and Pecos rivers that isolated the Southern High Plains from the Great Plains and has contributed significantly to the continuing retreat of the westward escarpment. Evaporative and dissolution processes are responsible for current plateau topography and the development of the signature 20,000 small playa basins and 40 to 50 large saline lake basins in the area. In conjunction with eolian processes, ground water transport controls the mineralogy of commercially valuable mineral deposits and sets up the distribution of fine efflorescent salts that adversely affect water quality. As the water table rises and retreats, lunette and tufa formation provides valuable paleoclimate data for the Southern High Plains. In all these cases, an understanding of ground water processes contributes valuable information to a broad range of geological topics, well beyond traditional interest in water supply and environmental issues.

  10. Hydrostatic pressure effect on micro air bubbles deposited on surfaces with a retreating tip.

    Science.gov (United States)

    Huynh, So Hung; Wang, Jingming; Yu, Yang; Ng, Tuck Wah

    2014-06-01

    The effect of hydrostatic pressure on 6 μL air bubbles formed on micropillar structured PDMS and silicone surfaces using a 2 mm diameter stainless steel tip retreated at 1 mm/s was investigated. Dimensional analysis of the tip retraction process showed the experiments to be conducted in the condition where fluid inertial forces are comparable in magnitude with surface tension forces, while viscous forces were lower. Larger bubbles could be left behind on the structured PDMS surface. For hydrostatic pressures in excess of 20 mm H2O (196 Pa), the volume of bubble deposited was found to decrease progressively with pressure increase. The differences in width of the deposited bubbles (in contact with the substrate) were significant at any particular pressure but marginal in height. The attainable height before rupture reduced with pressure increase, thereby accounting for the reducing dispensed volume characteristic. On structured PDMS, the gaseous bridge width (in contact with the substrate) was invariant with tip retraction, while on silicone it was initially reducing before becoming invariant in the lead up to rupture. With silicone, hence, reductions in the contact width and height were both responsible for reduced volumes with pressure increase. Increased hydrostatic pressure was also found to restrict the growth in contact width on silicone during the stage when air was injected in through the tip. The ability to effect bubble size in such a simple manner may already be harnessed in nature and suggests possibilities in technological applications.

  11. X-rays from Magnetically Confined Wind Shocks: Effect of Cooling-Regulated Shock Retreat

    CERN Document Server

    ud-Doula, Asif; Townsend, Richard; Petit, Veronique; Cohen, David

    2014-01-01

    We use 2D MHD simulations to examine the effects of radiative cooling and inverse Compton (IC) cooling on X-ray emission from magnetically confined wind shocks (MCWS) in magnetic massive stars with radiatively driven stellar winds. For the standard dependence of mass loss rate on luminosity $\\Mdot \\sim L^{1.7} $, the scaling of IC cooling with $L$ and radiative cooling with $\\Mdot$ means that IC cooling become formally more important for lower luminosity stars. However, because the sense of the trends is similar, we find the overall effect of including IC cooling is quite modest. More significantly, for stars with high enough mass loss to keep the shocks radiative, the MHD simulations indicate a linear scaling of X-ray luminosity with mass loss rate; but for lower luminosity stars with weak winds, X-ray emission is reduced and softened by a {\\em shock retreat} resulting from the larger post-shock cooling length, which within the fixed length of a closed magnetic loop forces the shock back to lower pre-shock w...

  12. Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves.

    Science.gov (United States)

    Liu, Yan; Moore, John C; Cheng, Xiao; Gladstone, Rupert M; Bassis, Jeremy N; Liu, Hongxing; Wen, Jiahong; Hui, Fengming

    2015-03-17

    Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.

  13. A connectionist model of the retreat from verb argument structure overgeneralization.

    Science.gov (United States)

    Ambridge, Ben; Blything, Ryan P

    2016-11-01

    A central question in language acquisition is how children build linguistic representations that allow them to generalize verbs from one construction to another (e.g., The boy gave a present to the girl → The boy gave the girl a present), whilst appropriately constraining those generalizations to avoid non-adultlike errors (e.g., I said no to her → *I said her no). Although a consensus is emerging that learners solve this problem using both statistical and semantics-based learning procedures (e.g., entrenchment, pre-emption, and semantic verb class formation), there currently exist few - if any - proposals for a learning model that combines these mechanisms. The present study used a connectionist model to test an account that argues for competition between constructions based on (a) verb-in construction frequency, (b) relevance of constructions for the speaker's intended message, and (c) fit between the fine-grained semantic properties of individual verbs and individual constructions. The model was able not only (a) to simulate the overall pattern of overgeneralization-then-retreat, but also (b) to use the semantics of novel verbs to predict their argument structure privileges (just as real learners do), and

  14. Influence of Glacier Retreat On The Water Yield From High Mountain Areas, Comparison Alps - Central Asia

    Science.gov (United States)

    Hagg, W.; Braun, L.

    The main objective of the study is the investigation of the link between glacier retreat and discharge in selected catchments in Central Asia and the comparison of these results with conditions in the Alps. For this purpose, the conceptual runoff model HBV-ETH has been applied in three glacierized basins in Kazakhstan, Kyrgyztan and China, which represent regions of different continentality. Operating only with air temperature and precipitation data, the model calculates discharge and other water balance components in a daily timestep. To evaluate the reaction of the simulated hydrograph to climate change, the meteorological model input has been modified, according to the results of regional climate modeling under the assumption of doubling of atmospheric CO2. These runoff scenarios were made for three different stages of deglacierization. The first results show a similar pattern as observed in the Alps in previous studies: under a present-day glacier extent the water yield rises drastically during the melting period, after a reduction of the glacierized area by 50 % the flood peaks are reduced to presently observed values, and after a complete disappearance of the glaciers the calculated runoff indicates a strong reduction of runoff during summer months, which would have a significant effect on the availability of water resources in these dry regions of Asia.

  15. The complex response of Arctic cloud condensation nuclei to sea-ice retreat

    Directory of Open Access Journals (Sweden)

    J. Browse

    2013-06-01

    Full Text Available Loss of summertime Arctic sea ice will lead to a large increase in the emission of aerosols and precursor gases from the ocean surface. It has been suggested that these enhanced emissions will exert substantial aerosol radiative forcings, dominated by the indirect effect of aerosol on clouds. Here, we investigate the potential for these indirect forcings using a global aerosol microphysics model evaluated against aerosol observations from the ASCOS campaign to examine the response of Arctic cloud condensation nuclei (CCN to sea-ice retreat. In response to a complete loss of summer ice, we find that north of 70° N emission fluxes of sea-salt, marine primary organic aerosol (OA and dimethyl sulphide increase by a factor of ~10, ~4 and ~15, respectively. However, the CCN response is weak, with negative changes over the central Arctic ocean. The weak response is due to the efficient scavenging of aerosol by extensive drizzling stratocumulus clouds. In the scavenging-dominated Arctic environment, the production of condensable vapour from oxidation of dimethyl sulphide grows particles to sizes where they can be scavenged. This loss is not sufficiently compensated by new particle formation, due to the suppression of nucleation by the large condensation sink resulting from sea-salt and primary OA emissions. Thus, our results suggest that increased aerosol emissions will not cause a climate feedback through changes in cloud microphysical and radiative properties.

  16. Retreatment efficacy and predictors of ledipasvir plus sofosbuvir to HCV genotype 1 in Japan.

    Science.gov (United States)

    Akuta, Norio; Sezaki, Hitomi; Suzuki, Fumitaka; Fujiyama, Shunichiro; Kawamura, Yusuke; Hosaka, Tetsuya; Kobayashi, Masahiro; Kobayashi, Mariko; Saitoh, Satoshi; Suzuki, Yoshiyuki; Arase, Yasuji; Ikeda, Kenji; Kumada, Hiromitsu

    2017-02-01

    Predictors of treatment efficacy with ledipasvir plus sofosbuvir as direct-acting antiviral (DAA) regimen for HCV infection are still unclear. Retreatment efficacy of ledipasvir plus sofosbuvir for failures to prior DAA regimens, including NS5A inhibitors, are also unknown because resistance-associated variants (RAVs) in NS5A have been shown to persist up to the long-term of post-treatment. One hundred seventy-five patients with chronic HCV genotype 1 infection, without decompensated liver cirrhosis and hepatocellular carcinoma, were evaluated SVR12 by ledipasvir 90 mg plus sofosbuvir 400 mg once-daily for 12 weeks. Overall, SVR12 were 92%, based on intention to treat analysis. In failures to daclatasvir plus asunaprevir, SVR12 were 71%. The study using ultra-deep sequencing showed that ledipasvir plus sofosbuvir was effective to one case of failures to daclatasvir plus asunaprevir with multidrug RAVs (triple mutation in NS3-D168/NS5A-L31/NS5A-Y93). Multivariate analysis identified FIB4 index (plus sofosbuvir for HCV genotype 1 infection, including multidrug RAVs in Japan. Treatment efficacy could be predicted by the combination of viral and host factors. J. Med. Virol. 89:284-290, 2017. © 2016 Wiley Periodicals, Inc.

  17. Growing educational differentials in the retreat from marriage among Korean men.

    Science.gov (United States)

    Park, Hyunjoon; Lee, Jae Kyung

    2017-08-01

    Applying discrete-time hazard models to person-year data constructed from 1% microdata sample of 2010 Korean Census, we explore how men's education affects their transition to first marriage, and how the relationship between education and marriage has changed across three 10-year birth cohorts of Korean men born from 1946 to 1975. Drawing on Oppenheimer's theory of marriage and review of changing educational and economic contexts of Korean men, we develop a hypothesis on growing educational differentials in marriage. We find that the high educated delay marriage until later ages but catch up to the extent to which they are eventually more likely to marry than the low educated. There is a continued trend across cohorts toward the delay and avoidance of marriage at all educational levels. However, the trend of retreat from marriage has been more substantial for men with high school or less education compared to men with a university degree, leading to growing educational gaps over time in marriage. Among the three cohorts, the youngest cohort, among which low educated men's economic prospects have particularly deteriorated due to rapid educational expansion and economic crisis, shows most pronounced decline in marriage. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Future increases in Arctic precipitation linked to local evaporation and sea-ice retreat.

    Science.gov (United States)

    Bintanja, R; Selten, F M

    2014-05-22

    Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation.

  19. Retreatment and surgical repair of the apical third perforation and osseous defect using mineral trioxide aggregate

    Directory of Open Access Journals (Sweden)

    A Savitha

    2013-01-01

    Full Text Available One of the causes of non-healing periapical pathosis in endodontically treated tooth is root perforation. This can occur pathologically by resorption and caries, iatrogenically during endodontic therapy (zip, strip, furcal perforations. Root perforation results in bacterial contamination, periradicular tissue injury, inflammation, and bone resorption. The purpose of this case report is to describe endodontic retreatment and surgical management of a longstanding periapical lesion on maxillary lateral incisor, associated with perforation and osseous defects using mineral trioxide aggregate (MTA. Although the majority of bone support and root dentin was damaged, an attempt was made to repair the defect and restore the tooth. After the surgical intervention and root canal treatment, the perforation was subsequently sealed with MTA. Later, the root was reinforced with composites and the tooth was restored with direct veneer. Conclusion: Four-and-a-half year (54 months recall examination showed no evidence of periodontal breakdown, no symptoms of further deterioration, and complete healing of periradicular lesions when examined by radiography. This case report presents a treatment strategy that could improve the healing process and beneficial outcomes for patients with perforation and osseous defect.

  20. West Antarctic Ice Sheet retreat driven by Holocene warm water incursions

    Science.gov (United States)

    Hillenbrand, Claus-Dieter; Smith, James A.; Hodell, David A.; Greaves, Mervyn; Poole, Christopher R.; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E.; Elderfield, Henry; Klages, Johan