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Sample records for ross sea drift

  1. Victoria Land, Ross Sea, and Ross Ice Shelf, Antarctica

    Science.gov (United States)

    2002-01-01

    On December 19, 2001, MODIS acquired data that produced this image of Antarctica's Victoria Land, Ross Ice Shelf, and the Ross Sea. The coastline that runs up and down along the left side of the image denotes where Victoria Land (left) meets the Ross Ice Shelf (right). The Ross Ice Shelf is the world's largest floating body of ice, approximately the same size as France. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  2. Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

    Science.gov (United States)

    Comiso, Josefino; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

    2011-01-01

    Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

  3. The South Pole and the Ross Sea

    Science.gov (United States)

    2002-01-01

    This image shows a rare clear view of the South Pole (lower right) and the Ross Sea, Antarctica. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) acquired the scene on December 26, 2001. The geographic South Pole is located in the center of Antarctica, at an altitude of 2,900 meters (9,300 feet). It rests on a continent-wide ice sheet that is 2,870 m thick, with the underlying bedrock only 30 m (98 feet) above sea level. The ice underlying the South Pole is as much as 140,000 years old, and is currently accumulating at about 82 cm (32 inches) per year. Roughly 2,500 km (1,550 miles) away is the green water of the Ross Sea, which indicates the presence of large numbers of phytoplankton. This is a highly productive part of the world's oceans. Also note the ice gathered around McMurdo Sound, seen toward the lefthand shoreline of the Ross Sea, at the edge of the Ross Ice Shelf. According to National Science Foundation researchers, this ice is making it difficult for penguins to reach their food supply. Separating the continental Antarctic ice sheet from the Ross Sea are the Queen Maud Mountains and the Ross Ice Shelf. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  4. Phenolic compounds in Ross Sea water

    Science.gov (United States)

    Zangrando, Roberta; Barbaro, Elena; Gambaro, Andrea; Barbante, Carlo; Corami, Fabiana; Kehrwald, Natalie; Capodaglio, Gabriele

    2016-04-01

    Phenolic compounds are semi-volatile organic compounds produced during biomass burning and lignin degradation in water. In atmospheric and paleoclimatic ice cores studies, these compounds are used as biomarkers of wood combustion and supply information on the type of combusted biomass. Phenolic compounds are therefore indicators of paleoclimatic interest. Recent studies of Antarctic aerosols highlighted that phenolic compounds in Antarctica are not exclusively attributable to biomass burning but also derive from marine sources. In order to study the marine contribution to aerosols we developed an analytical method to determine the concentration of vanillic acid, vanillin, p-coumaric acid, syringic acid, isovanillic acid, homovanillic acid, syringaldehyde, acetosyringone and acetovanillone present in dissolved and particle phases in Sea Ross waters using HPLC-MS/MS. The analytical method was validated and used to quantify phenolic compounds in 28 sea water samples collected during a 2012 Ross Sea R/V cruise. The observed compounds were vanillic acid, vanillin, acetovanillone and p-coumaric acid with concentrations in the ng/L range. Higher concentrations of analytes were present in the dissolved phase than in the particle phase. Sample concentrations were greatest in the coastal, surficial and less saline Ross Sea waters near Victoria Land.

  5. Amphibian Seismological Studies in the Ross Sea, Antarctica

    Science.gov (United States)

    Schmidt-Aursch, Mechita; Kuk Hong, Jong; Lee, Won Sang; Geissler, Wolfram; Yun, Sukyoung; Gohl, Karsten; Park, Yongcheol; Yoo, Hyun Jae

    2016-04-01

    The Antarctic Ross Sea is one of the key regions for polar research activities. Research stations from several countries located at the coast are the base for inland expeditions. Even in the austral summer, the Ross Sea is party covered with drifting ice fields; this requires an icebreaker for all marine explorations. Therefore, large geophysical surveys in the Ross Sea are difficult. But the area is of special interest for seismologists: The Terror Rift in the western Ross Sea is a prominent neotectonic structure of the West Antarctic Rift System (WARS). It is located near the coast in the Victoria Land Basin and extends parallel to the Transantarctic Mountains. The rifting processes and the accompanying active onshore volcanism lead to increased seismicity in the region. The annual waxing and waning of the sea-ice and the dynamics of the large Ross Ice Shelf and nearby glaciers generate additional seismic signals. Investigation on seismological activities associated with the WARS and the cryogenic signals simultaneously would give us an unprecedented opportunity to have a better understanding of the Evolution of the WARS (EWARS) and the rapid change in the cryospheric environment nearby. The Korea Polar Research Institute (KOPRI) and the Alfred-Wegener-Institut (AWI) have conducted a pilot study off the Korean Jang Bogo research station in the Terra Nova Bay by developing a collaborative research program (EWARS) since 2011 to explore seismicity and seismic noise in this region. Four broadband ocean-bottom seismometers (OBS) from the German DEPAS pool were deployed in January 2012 with the Korean research icebreaker RV Araon. Three instruments could successfully be recovered after 13 months, the fourth OBS was not accessible due to local sea-ice coverage. We have successfully completed a second recovery operation in January 2014. All stations recorded data of good quality, one station stopped after 8 months due to a recorder error. The OBS recovered in 2014

  6. Western Ross Sea continental slope gravity currents

    Science.gov (United States)

    Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin

    2009-06-01

    Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ˜100 to ˜400 m on proceeding downslope from ˜600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ˜35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (-1.9 °C; 34.79) and approaching 1.5 m s -1 at descent angles as large as ˜60° relative to the isobaths. Such events were most common during November-May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real

  7. Decadal trends in air-sea CO2 exchange in the Ross Sea (Antarctica)

    Science.gov (United States)

    Tagliabue, Alessandro; Arrigo, Kevin R.

    2016-05-01

    Highly productive Antarctic shelf systems, like the Ross Sea, play important roles in regional carbon budgets, but the drivers of local variations are poorly quantified. We assess the variability in the Ross Sea carbon cycle using a regional physical-biogeochemical model. Regionally, total partial pressure of CO2 (pCO2) increases are largely controlled by the biological pump and broadly similar to those in the offshore Southern Ocean. However, this masks substantial local variability within the Ross Sea, where interannual fluctuations in total pCO2 are driven by the biological pump and alkalinity, whereas those for anthropogenic pCO2 are related to physical processes. Overall, the high degree of spatial variability in the Ross Sea carbon cycle causes extremes in aragonite saturation that can be as large as long-term trends. Therefore, Antarctic shelf polynya systems like the Ross Sea will be strongly affected by local processes in addition to larger-scale phenomena.

  8. Ross sea ice motion, area flux, and deformation

    Science.gov (United States)

    kwok, Ron

    2005-01-01

    The sea ice motion, area export, and deformation of the Ross Sea ice cover are examined with satellite passive microwave and RADARSAT observations. The record of high-resolution synthetic aperture radar (SAR) data, from 1998 and 2000, allows the estimation of the variability of ice deformation at the small scale (10 km) and to assess the quality of the longer record of passive microwave ice motion. Daily and subdaily deformation fields and RADARSAT imagery highlight the variability of motion and deformation in the Ross Sea. With the passive microwave ice motion, the area export at a flux gate positioned between Cape Adare and Land Bay is estimated. Between 1992 and 2003, a positive trend can be seen in the winter (March-November) ice area flux that has a mean of 990 x 103 km2 and ranges from a low of 600 x 103 km2 in 1992 to a peak of 1600 x 103 km2 in 2001. In the mean, the southern Ross Sea produces almost twice its own area of sea ice during the winter. Cross-gate sea level pressure (SLP) gradients explain 60% of the variance in the ice area flux. A positive trend in this gradient, from reanalysis products, suggests a 'spinup' of the Ross Sea Gyre over the past 12 yr. In both the NCEP-NCAR and ERA-40 surface pressure fields, longer-term trends in this gradient and mean SLP between 1979 and 2002 are explored along with positive anomalies in the monthly cross-gate SLP gradient associated with the positive phase of the Southern Hemisphere annular mode and the extrapolar Southern Oscillation.

  9. Note On The Ross Sea Shelf Water Downflow Processes (antarctica)

    Science.gov (United States)

    Bergamasco, A.; Defendi, V.; Spezie, G.; Budillon, G.; Carniel, S.

    In the framework of the CLIMA Project of the Italian National Program for Research in Antarctica, three different experimental data sets were acquired along the continental shelf break; two of them (in 1997 and 2001) close to Cape Adare, the 1998 one in the middle of the Ross Sea (i.e. 75 S, 177 W). The investigations were chosen in order to explore the downslope flow of the bottom waters produced in the Ross Sea, namely the High Salinity Shelf Water (HSSW, the densest water mass of the southern ocean coming from its formation site in the polynya region in Terra Nova bay), and the Ice Shelf Water (ISW, originated below the Ross Ice Shelf and outflowing northward). Both bottom waters spill over the shelf edge and mix with the Circumpolar Deep Water (CDW) contributing to the formation of the Antarctic Bottom Waters (AABW). Interpreting temperature, salinity and density maps in terms of cascading processes, both HSSW and ISW overflows are evidenced during, respectively, 1997 and 1998. During the 2001 acquisition there is no presence of HSSW along the shelf break, nevertheless distribution captures the evidence of a downslope flow process.

  10. Downslope flow across the Ross Sea shelf break (Antarctica)

    Science.gov (United States)

    Bergamasco, A.; Budillon, G.; Carniel, S.; Defendi, V.; Meloni, R.; Paschini, E.; Sclavo, M.; Spezie, G.

    2003-12-01

    The analysis of some high-resolution hydrological data sets acquired during the 1997, 1998, 2001 and 2003 austral summers across the Ross Sea continental shelf break are here presented. The main focus of these cruises carried out in the framework of the Italian National Antarctic Program was the investigation of the downslope flow of the dense waters originated inside the Ross Sea. Such dense waters, flow near the bottom and, reaching the continental shelf break, ventilate the deep ocean. Two Antarctic continental shelf mechanisms can originate dense and deep waters. The former mechanism involves the formation, along the Victoria Land coasts, of a dense and saline water mass, the High Salinity Shelf Water (HSSW). The HSSW formation is linked to the rejection of salt into the water column as sea ice freezes, especially during winter, in the polynya areas, where the ice is continuously pushed offshore by the strong katabatic winds. The latter one is responsible of the formation of a supercold water mass, the Ice Shelf Water (ISW). The salt supplied by the HSSW recirculated below the Ross Ice Shelf, the latent heat of melting and the heat sink provided by the Ross Ice Shelf give rise to plumes of ISW, characterized by temperatures below the sea-surface freezing point. The dense shelf waters migrate to the continental shelf-break, spill over the shelf edge and descend the continental slope as a shelf-break gravity current, subject to friction and possibly enhanced by topographic channelling. Friction, in particular, breaks the constraint of potential vorticity conservation, counteracting the geostrophic tendency for along slope flow. The density-driven downslope motion or cascading entrains ambient water, namely the lower layer of the CDW, reaches a depth where density is the same and spreads off-slope. In fact, the cascading event is inhibited by friction without entrainment. The downslope processes are important for the ocean and climate system because they play a

  11. Does temperature structure phytoplankton community composition in the Ross Sea, Antarctica?

    Science.gov (United States)

    The Ross Sea polynya experiences one of the largest phytoplankton blooms in the Southern Ocean. Energy flow potential within the Ross Sea food web is primarily set by diatoms and prymnesiophytes, the latter dominated by Phaeocystis antarctica. We investigated physical, chemical,...

  12. Atmospheric forcing of sea ice anomalies in the Ross Sea polynya region

    Science.gov (United States)

    Dale, Ethan R.; McDonald, Adrian J.; Coggins, Jack H. J.; Rack, Wolfgang

    2017-01-01

    We investigate the impacts of strong wind events on the sea ice concentration within the Ross Sea polynya (RSP), which may have consequences on sea ice formation. Bootstrap sea ice concentration (SIC) measurements derived from satellite SSM/I brightness temperatures are correlated with surface winds and temperatures from Ross Ice Shelf automatic weather stations (AWSs) and weather models (ERA-Interim). Daily data in the austral winter period were used to classify characteristic weather regimes based on the percentiles of wind speed. For each regime a composite of a SIC anomaly was formed for the entire Ross Sea region and we found that persistent weak winds near the edge of the Ross Ice Shelf are generally associated with positive SIC anomalies in the Ross Sea polynya and vice versa. By analyzing sea ice motion vectors derived from the SSM/I brightness temperatures we find significant sea ice motion anomalies throughout the Ross Sea during strong wind events, which persist for several days after a strong wind event has ended. Strong, negative correlations are found between SIC and AWS wind speed within the RSP indicating that strong winds cause significant advection of sea ice in the region. We were able to partially recreate these correlations using colocated, modeled ERA-Interim wind speeds. However, large AWS and model differences are observed in the vicinity of Ross Island, where ERA-Interim underestimates wind speeds by a factor of 1.7 resulting in a significant misrepresentation of RSP processes in this area based on model data. Thus, the cross-correlation functions produced by compositing based on ERA-Interim wind speeds differed significantly from those produced with AWS wind speeds. In general the rapid decrease in SIC during a strong wind event is followed by a more gradual recovery in SIC. The SIC recovery continues over a time period greater than the average persistence of strong wind events and sea ice motion anomalies. This suggests that sea ice

  13. Three artotrogids (Crustacea: Copepoda: Siphonostomatoida from the Ross Sea, Antarctica

    Directory of Open Access Journals (Sweden)

    Mercedes Conradi

    2014-12-01

    Full Text Available The Artotrogidae, one of the most primitive of siphonostomatoid families, consists currently of 117 species in 21 genera. Most of these species (65% are poorly or incompletely described since they have been rarely recorded in recent decades and, when encountered, have been found in very low numbers. During the 19th Italian Antarctic Expedition, with the RV Italica, to the Ross Sea in austral summer 2004, some artotrogid copepods were collected. This paper redescribes two species of artotrogid copepods, which are known only from the Southern Ocean, Neobradypontius neglectus and Cryptopontius latus, and describes for the first time a male of the genus Neobradypontius. Furthermore, a new species is described and added to Sestropontius, increasing the number of known species of this genus to three. The main discrepancies between the original descriptions and the specimens of the two species collected from the Ross Sea redescribed here were on the armature of the antennary exopod and leg 5. The new species, Sestropontius italicae, shares with its most similar congener, S. mckinnoni, the armature of the third endopodal segment of leg 1 and leg 2 and that of the third exopodal segment of leg 4. However, the segmentation of the antennae and the armature on the antennary exopod are different.

  14. The oceanography and ecology of the Ross Sea.

    Science.gov (United States)

    Smith, Walker O; Ainley, David G; Arrigo, Kevin R; Dinniman, Michael S

    2014-01-01

    The continental shelf of the Ross Sea exhibits substantial variations in physical forcing, ice cover, and biological processes on a variety of time and space scales. Its circulation is characterized by advective inputs from the east and exchanges with off-shelf regions via the troughs along the northern portions. Phytoplankton biomass is greater there than anywhere else in the Antarctic, although nitrate is rarely reduced to levels below 10 μmol L(-1). Overall growth is regulated by irradiance (via ice at the surface and by the depths of the mixed layers) and iron concentrations. Apex predators reach exceptional abundances, and the world's largest colonies of Adélie and emperor penguins are found there. Krill are represented by two species (Euphausia superba near the shelf break and Euphausia crystallorophias throughout the continental shelf region). Equally important and poorly known is the Antarctic silverfish (Pleuragramma antarcticum), which is also consumed by most upper-trophic-level predators. Future changes in the Ross Sea environment will have profound and unpredictable effects on the food web.

  15. The Satellite Passive-Microwave Record of Sea Ice in the Ross Sea Since Late 1978

    Science.gov (United States)

    Parkinson, Claire L.

    2009-01-01

    Satellites have provided us with a remarkable ability to monitor many aspects of the globe day-in and day-out and sea ice is one of numerous variables that by now have quite substantial satellite records. Passive-microwave data have been particularly valuable in sea ice monitoring, with a record that extends back to August 1987 on daily basis (for most of the period), to November 1970 on a less complete basis (again for most of the period), and to December 1972 on a less complete basis. For the period since November 1970, Ross Sea sea ice imagery is available at spatial resolution of approximately 25 km. This allows good depictions of the seasonal advance and retreat of the ice cover each year, along with its marked interannual variability. The Ross Sea ice extent typically reaches a minimum of approximately 0.7 x 10(exp 6) square kilometers in February, rising to a maximum of approximately 4.0 x 10(exp 6) square kilometers in September, with much variability among years for both those numbers. The Ross Sea images show clearly the day-by-day activity greatly from year to year. Animations of the data help to highlight the dynamic nature of the Ross Sea ice cover. The satellite data also allow calculation of trends in the ice cover over the period of the satellite record. Using linear least-squares fits, the Ross Sea ice extent increased at an average rate of 12,600 plus or minus 1,800 square kilometers per year between November 1978 and December 2007, with every month exhibiting increased ice extent and the rates of increase ranging from a low of 7,500 plus or minus 5,000 square kilometers per year for the February ice extents to a high of 20,300 plus or minus 6,100 kilometers per year for the October ice extents. On a yearly average basis, for 1979-2007 the Ross Sea ice extent increased at a rate of 4.8 plus or minus 1.6 % per decade. Placing the Ross Sea in the context of the Southern Ocean as a whole, over the November 1978-December 2007 period the Ross Sea had

  16. 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.

  17. Applicability of highly branched isoprenoids as a sea ice proxy in the Ross Sea

    Science.gov (United States)

    Kim, Jung-Hyun; Lee, Jae Il; Belt, Simon T.; Gal, Jong-Ku; Smik, Lukas; Shin, Kyung-Hoon

    2016-04-01

    Sea ice is an integral component of the polar climate system, constraining the effect of changing surface albedo, ocean-atmosphere heat exchanges, the formation of deep and intermediate waters that participate in driving the meridional overturning circulation and thus global climate. In recent years, a mono-unsaturated highly branched isoprenoid (HBI) alkene which is biosynthesised by certain sea ice diatoms during the spring bloom and, upon ice melt, deposited into underlying sediments, has been uniquely observed in Arctic sea ice and in Arctic sediments. Hence, the term IP25 (ice proxy with 25 carbon atoms) was proposed to distinguish this compound from other HBI isomers and has become an established proxy for the reconstruction of Arctic sea ice. In contrast, a monounsaturated HBI alkene, i.e. IP25, has not been observed in sea ice or sediments from the Antarctic. Hence, the application of diene and triene HBI concentrations and the resulting diene/triene (D/T) ratio was alternatively introduced as sea ice/open water indicators in the Southern Ocean. However, there is still lack of data covering the wide areas around the Antarctic, especially from the Ross Sea. Hence, we investigated surface sediment samples from the Ross Sea (n=14) collected during the R/V ARAON cruise in 2015 as well as from the Antarctic Peninsula (n=17) collected during several R/V ARAON cruises between 2001 and 2013. We will present our preliminary results and will discuss the applicability of the HBI in the Ross Sea.

  18. Ambient Seismic Signals Observed in Iceberg?Filled Waters of the Ross Sea, Antarctica.

    Science.gov (United States)

    Macayeal, D. R.; Okal, E. A.; Aster, R. C.

    2006-12-01

    A two-year seismometer deployment on various icebergs in the Ross Sea and on the Ross Ice Shelf (PASSCAL project SOUTHBERG) have produced an unusual seismological "tone poem" constituting a sample of ambient conditions in an iceberg-covered, coastal sea of Antarctica. The original motivation of the project was to investigate the source of signals seen as T-phases in the equatorial Pacific [e.g., Talandier et al., 2002]. During the periods of continuous seismometer operation (i.e., during the October - April periods of 2003-4 and 2004-5 when photovoltaic charging systems kept seismometers in operation) on icebergs B15A, C16 and Nascent Iceberg (a site not yet calved from the Ross Ice Shelf), about 1300 events were observed (roughly one event per day). These events are attributed to the icebergs, and are loosely referred to as "iceberg tremor" due to their long duration (many hours) and spectral structure (e.g., characterized by clearly preferential frequencies in the 1-3 Hz range, accompanied by multiple harmonics of a variable-pitch fundamental). The purpose of this presentation is to give a general qualitative overview of the various categories of iceberg tremor, and to describe their relationship to other variables observed (e.g., iceberg drift velocity, iceberg-on-iceberg collision, iceberg-on-seabed scraping). Speculation on the cause or causes of iceberg tremor will be postponed pending further study. Suggestions as to the relationship between the ambient tone poem of iceberg-covered waters and hydro-acoustic and seismic signals seen in the ocean beyond Antarctica will be offered.

  19. Atmospheric forcing of sea ice anomalies in the Ross Sea Polynya region

    Science.gov (United States)

    Dale, Ethan; McDonald, Adrian; Rack, Wolfgang

    2016-04-01

    Despite warming trends in global temperatures, sea ice extent in the southern hemisphere has shown an increasing trend over recent decades. Wind-driven sea ice export from coastal polynyas is an important source of sea ice production. Areas of major polynyas in the Ross Sea, the region with largest increase in sea ice extent, have been suggested to produce the vast amount of the sea ice in the region. We investigate the impacts of strong wind events on polynyas and the subsequent sea ice production. We utilize Bootstrap sea ice concentration (SIC) measurements derived from satellite based, Special Sensor Microwave Imager (SSM/I) brightness temperature images. These are compared with surface wind measurements made by automatic weather stations of the University of Wisconsin-Madison Antarctic Meteorology Program. Our analysis focusses on the winter period defined as 1st April to 1st November in this study. Wind data was used to classify each day into characteristic regimes based on the change of wind speed. For each regime, a composite of SIC anomaly was formed for the Ross Sea region. We found that persistent weak winds near the edge of the Ross Ice Shelf are generally associated with positive SIC anomalies in the Ross Sea polynya area (RSP). Conversely we found negative SIC anomalies in this area during persistent strong winds. By analyzing sea ice motion vectors derived from SSM/I brightness temperatures, we find significant sea ice motion anomalies throughout the Ross Sea during strong wind events. These anomalies persist for several days after the strong wing event. Strong, negative correlations are found between SIC within the RSP and wind speed indicating that strong winds cause significant advection of sea ice in the RSP. This rapid decrease in SIC is followed by a more gradual recovery in SIC. This increase occurs on a time scale greater than the average persistence of strong wind events and the resulting Sea ice motion anomalies, highlighting the production

  20. Correlated Energy Exchange in Drifting Sea Ice

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2011-01-01

    Full Text Available The ice floe speed variations were monitored at the research camp North Pole 35 established on the Arctic ice pack in 2008. A three-month time series of measured speed values was used for determining changes in the kinetic energy of the drifting ice floe. The constructed energy distributions were analyzed by methods of nonextensive statistical mechanics based on the Tsallis statistics for open nonequilibrium systems, such as tectonic formations and drifting sea ice. The nonextensivity means the nonadditivity of externally induced energy changes in multicomponent systems due to dynamic interrelation of components having no structural links. The Tsallis formalism gives one an opportunity to assess the correlation between ice floe motions through a specific parameter, the so-called parameter of nonextensivity. This formalistic assessment of the actual state of drifting pack allows one to forecast some important trends in sea ice behavior, because the level of correlated dynamics determines conditions for extended mechanical perturbations in ice pack. In this work, we revealed temporal fluctuations of the parameter of nonextensivity and observed its maximum value before a large-scale sea ice fragmentation (faulting of consolidated sea ice. The correlation was not detected in fragmented sea ice where long-range interactions are weakened.

  1. Multichannel Seismic Reflection Data - SCAR - Ross Sea 1987-1988, SDLS CD-ROM vol 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from six lines recorded during 1988 in the Ross Sea, Antarctica, by the Bundesanstalt fur...

  2. Multichannel Seismic Reflection Data - SCAR - Ross Sea 1980, SDLS, CD-ROM vol 5

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from eleven lines recorded during 1980 in the Ross Sea, Antarctica, by the Bundesanstalt fur...

  3. Multichannel Seismic Reflection Data - SCAR - Ross Sea 1982, SDLS CD-ROM vol 12

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from seven lines recorded during 1982 in the Ross Sea, Antarctica, by the Institut Francais du...

  4. Multichannel Seismic Reflection Data - SCAR - Ross Sea - 1987, SDLS CD-ROM vol 13

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during the 1987 field season in the Ross Sea, Antarctica, by SEVMORGEOLOGIA, RUSSIA. The...

  5. Multichannel Seismic Reflection Data - SCAR - Ross Sea - 1980, SDLS, CD-ROM vol 4

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from seven lines recorded during 1980 in the Ross Sea, Antarctica, by the Bundesanstalt fur...

  6. Multichannel Seismic Reflection Data - SCAR - Ross Sea - 1980, SDLS CD-ROM vol 3

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from four lines recorded during 1980 in the Ross Sea, Antarctica, by the Bundesanstalt fur...

  7. Multichannel Seismic Reflection Data - SCAR - Ross Sea - 1989, SDLS CD-ROM vol 14

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1989 field season in the Ross Sea, Antarctica, by the SEVMORGEOLOGIA, RUSSIS. The...

  8. Multichannel Seismic Reflection Data - SCAR, Ross Sea - 1982-1983, CD-ROM vol 9

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data from fourteen lines recorded during 1982 in the Ross Sea and Wilkes Island, Antarctica, by the...

  9. Neogene Development of the Terror Rift, western Ross Sea, Antarctica

    Science.gov (United States)

    Sauli, C.; Sorlien, C. C.; Busetti, M.; De Santis, L.; Wardell, N.; Henrys, S. A.; Geletti, R.; Wilson, T. J.; Luyendyk, B. P.

    2015-12-01

    Terror Rift is a >300 km-long, 50-70 km-wide, 14 km-deep sedimentary basin at the edge of the West Antarctic Rift System, adjacent to the Transantarctic Mountains. It is cut into the broader Victoria Land Basin (VLB). The VLB experienced 100 km of mid-Cenozoic extension associated with larger sea floor spreading farther north. The post-spreading (Neogene) development of Terror Rift is not well understood, in part because of past use of different stratigraphic age models. We use the new Rossmap seismic stratigraphy correlated to Cape Roberts and Andrill cores in the west and to DSDP cores in the distant East. This stratigraphy, and new fault interpretations, was developed using different resolutions of seismic reflection data included those available from the Seismic Data Library System. Depth conversion used a new 3D velocity model. A 29 Ma horizon is as deep as 8 km in the south, and a 19 Ma horizon is >5 km deep there and 4 km-deep 100 km farther north. There is a shallower northern part of Terror Rift misaligned with the southern basin across a 50 km right double bend. It is bounded by steep N-S faults down-dropping towards the basin axis. Between Cape Roberts and Ross Island, the Oligocene section is also progressively-tilted. This Oligocene section is not imaged within northern Terror Rift, but the simplest hypothesis is that some of the Terror Rift-bounding faults were active at least during Oligocene through Quaternary time. Many faults are normal separation, but some are locally vertical or even reverse-separation in the upper couple of km. However, much of the vertical relief of the strata is due to progressive tilting (horizontal axis rotation) and not by shallow faulting. Along the trend of the basin, the relief alternates between tilting and faulting, with a tilting margin facing a faulted margin across the Rift, forming asymmetric basins. Connecting faults across the basin form an accommodation zone similar to other oblique rifts. The Neogene basin is

  10. Changes in sea-ice cover and temperature in the Western Ross Sea during the Holocene

    Science.gov (United States)

    Fleury, Sophie; Kim, Jung-Hyun; Gal, Jong-Ku; Mezgec, Karin; Belt, Simon; Smik, Lukas; Stenni, Barbara; Melis, Romana; Crosta, Xavier; Shin, Kyung-Hoon

    2016-04-01

    Although changes in sea-ice cover contribute to global climatic variations, they are poorly constrained for periods earlier than the last decades. More records are especially required around Antarctica, where the formation of Antarctic Bottom Waters participates to global thermohaline circulation. However, this region provided only a few marine sediment cores spanning the entire Holocene, especially because of generally low sedimentation rates. This study focuses on marine sediment core ANTA99-CJ5 (73°49'S; 175°39'E), located in the open sea ice zone (OSIZ) of the western Ross Sea. We analyzed several lipid biomarkers: highly branched isoprenoids (HBIs), sterols, diols and GDGTs. The combination of several biomarkers and the comparison of these results with a diatom record previously published on the same core enabled us to trace past changes in temperatures as well as in sea-ice condition over the last 11,600 years.

  11. Ice core reconstruction of sea ice change in the Amundsen-Ross Seas since 1702 A.D.

    Science.gov (United States)

    Thomas, Elizabeth R.; Abram, Nerilie J.

    2016-05-01

    Antarctic sea ice has been increasing in recent decades, but with strong regional differences in the expression of sea ice change. Declining sea ice in the Bellingshausen Sea since 1979 (the satellite era) has been linked to the observed warming on the Antarctic Peninsula, while the Ross Sea sector has seen a marked increase in sea ice during this period. Here we present a 308 year record of methansulphonic acid from coastal West Antarctica, representing sea ice conditions in the Amundsen-Ross Sea. We demonstrate that the recent increase in sea ice in this region is part of a longer trend, with an estimated ~1° northward expansion in winter sea ice extent (SIE) during the twentieth century and a total expansion of ~1.3° since 1702. The greatest reconstructed SIE occurred during the mid-1990s, with five of the past 30 years considered exceptional in the context of the past three centuries.

  12. Paleobathymetric Reconstruction of Ross Sea: seismic data processing and regional reflectors mapping

    Science.gov (United States)

    Olivo, Elisabetta; De Santis, Laura; Wardell, Nigel; Geletti, Riccardo; Busetti, Martina; Sauli, Chiara; Bergamasco, Andrea; Colleoni, Florence; Vanzella, Walter; Sorlien, Christopher; Wilson, Doug; De Conto, Robert; Powell, Ross; Bart, Phil; Luyendyk, Bruce

    2017-04-01

    PURPOSE: New maps of some major unconformities of the Ross Sea have been reconstructed, by using seismic data grids, combined with the acoustic velocities from previous works, from new and reprocessed seismic profiles. This work is carried out with the support of PNRA and in the frame of the bilateral Italy-USA project GLAISS (Global Sea Level Rise & Antarctic Ice Sheet Stability predictions), funded by the Ministry of Foreign Affairs. Paleobathymetric maps of 30, 14 and 4 million years ago, three 'key moments' for the glacial history of the Antarctic Ice Sheet, coinciding with global climatic changes. The paleobathymetric maps will then be used for numeric simulations focused on the width and thickness of the Ross Sea Ice Sheet. PRELIMINARY RESULTS: The first step was to create TWT maps of three main unconformity (RSU6, RSU4, and RSU2) of Ross Sea, revisiting and updating the ANTOSTRAT maps, through the interpretation of sedimentary bodies and erosional features, used to infer active or old processes along the slope, we identified the main seismic unconformities. We used the HIS Kingdom academic license. The different groups contribution was on the analysis of the Eastern Ross Sea continental slope and rise (OGS), of the Central Basin (KOPRI) of the western and central Ross Sea (Univ. of Santa Barbara and OGS), where new drill sites and seismic profiles were collected after the publication of the ANTOSTRAT maps. Than we joined our interpretation with previous interpretations. We examined previous processing of several seismic lines and all the old acoustic velocity analysis. In addiction we reprocessed some lines in order to have a higher data coverage. Then, combining the TWT maps of the unconformity with the old and new speed data we created new depth maps of the study area. The new depth maps will then be used for reconstructing the paleobathymetry of the Ross Sea by applying backstripping technique.

  13. Increase of the Antarctic Sea Ice Extent is highly significant only in the Ross Sea

    Science.gov (United States)

    Yuan, Naiming; Ding, Minghu; Ludescher, Josef; Bunde, Armin

    2017-01-01

    In the context of global warming, the question of why Antarctic sea ice extent (SIE) has increased is one of the most fundamental unsolved mysteries. Although many mechanisms have been proposed, it is still unclear whether the increasing trend is anthropogenically originated or only caused by internal natural variability. In this study, we employ a new method where the underlying natural persistence in the Antarctic SIE can be correctly accounted for. We find that the Antarctic SIE is not simply short-term persistent as assumed in the standard significance analysis, but actually characterized by a combination of both short- and long-term persistence. By generating surrogate data with the same persistence properties, the SIE trends over Antarctica (as well as five sub-regions) are evaluated using Monte-Carlo simulations. It is found that the SIE trends over most sub-regions of Antarctica are not statistically significant. Only the SIE over Ross Sea has experienced a highly significant increasing trend (p = 0.008) which cannot be explained by natural variability. Influenced by the positive SIE trend over Ross Sea, the SIE over the entire Antarctica also increased over the past decades, but the trend is only at the edge of being significant (p = 0.034).

  14. Glacial geomorphology of the Victoria Valley System, Ross Sea Region, Antarctica

    Science.gov (United States)

    Bockheim, James G.; McLeod, Malcolm

    2013-07-01

    During the 2011-2012 austral summer, we had the opportunity to verify a surficial geology map prepared nearly 50 years ago for the Victoria Valley system (VVS), the largest of the McMurdo Dry Valleys. We used high-resolution landsat images and a digital elevation model to identify landforms and prepare detailed maps of each of the five valleys in the VVS, including lateral and end moraines, rock glaciers, gelifluction sheets, gravel ripples, and hummocky and ice-cored drifts. Our mapping suggests that the Bull drift is less extensive than previously thought, attains a maximum elevation of ~ 750 m in Balham and Barwick Valleys and the upper Bull Pass region, and does not occur in McKelvey Valley. We found Insel drift to 850 m elevation in eastern McKelvey Valley and upper Bull Pass and were able to trace Insel drift down Bull Pass where it becomes Peleus drift in Wright Valley. The Victoria Lower Glacier likely responded to grounding of ice in the Ross Embayment and was out-of-phase with alpine glaciers elsewhere in the VVS. We amplified and quantified Calkin's relative chronology and provide here our multiple-parameter relative chronology for the McMurdo Dry Valleys that is based on surface-boulder weathering, soil weathering, salt stage, degree of development of the desert pavement, and form of patterned ground. Except for Victoria Lower Valley, we correlate Packard drift with Taylor II drift (ca., 120 ka), Vida drift with Taylor III drift (ca., 300 ka), Bull drift with Taylor IVb drift (2.7-3.5 Ma, and Insel drift with Peleus drift (> 3.7 Ma, < 5.4 Ma). The lack of a strong correlation between soil salt stage and depth of visible salts with elevation leads us to question whether a high-level lake (ca., 200 m deep) existed in the VVS during the early Holocene.

  15. First stage of INTRAMAP: INtegrated Transantarctic Mountains and Ross Sea Area Magnetic Anomaly Project

    Directory of Open Access Journals (Sweden)

    D. Damaske

    1999-06-01

    Full Text Available INTRAMAP (INtegrated Transantarctic Mountains and Ross Sea Area Magnetic Anomaly Project is an international effort to merge the magnetic data acquired throughout the "Ross Sea Antarctic Sector" (south of 60°S between 135°-255°E including the Transantarctic Mountains (TAM, the Ross Sea, Marie Byrd Land, and the Pacific coast, and also to begin the compilation efforts for new data over the Wilkes Basin. This project is a component of the continental scale Antarctic Digital Magnetic Anomaly Project (ADMAP. The first stage of INTRAMAP addresses the analysis and merging of GITARA (1991-1994 and GANOVEX (1984 aeromagnetic surveys together with ground magnetic data (1984-1989. The combined data sets cover an area of approximately 30 km2 over Victoria Land and adjacent Ross Sea. Map and profile gridding were implemented to integrate the data sets. These approaches are studied for improving existing strategies to adopt for the whole magnetic compilation effort. The final microlevelled grid that we produce is a new tool for regional interpretation of the main tectonic and geologic features of this sector of Antarctica.

  16. Sources of iron in the Ross Sea Polynya in early summer

    NARCIS (Netherlands)

    Gerringa, L. J. A.; Laan, P.; van Dijken, G. L.; van Haren, H.; De Baar, H. J. W.; Arrigo, K. R.; Alderkamp, A. -C.

    2015-01-01

    Dissolved Fe (DFe) was measured in the Ross Sea Polynya (RSP), Antarctica, during a GEOTRACES cruise between 20 December 2013 and 5 January 2014. DFe was measured over the full water column with special emphasis on samples near the seafloor. In the upper mixed layer, DFe was very low everywhere (

  17. Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica

    Science.gov (United States)

    Ryan-Keogh, Thomas J.; DeLizo, Liza M.; Smith, Walker O.; Sedwick, Peter N.; McGillicuddy, Dennis J.; Moore, C. Mark; Bibby, Thomas S.

    2017-02-01

    The bioavailability of iron influences the distribution, biomass and productivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (> 24 h) and short-term (24 h) iron-addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December-February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (σPSII) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplankton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea.

  18. Sources of iron in the Ross Sea Polynya in early summer

    NARCIS (Netherlands)

    Gerringa, L.J.A.; Laan, P.; van Dijken, G.L.; van Haren, H.; de Baar, H.J.W.; Arrigo, K.R.; Alderkamp, A.-C.

    2015-01-01

    Dissolved Fe (DFe) was measured in the Ross Sea Polynya (RSP), Antarctica, during a GEOTRACES cruise between 20 December 2013 and 5 January 2014. DFe was measured over the full water column with special emphasis on samples near the seafloor. In the upper mixed layer, DFe was very low everywhere (< 0

  19. Sources of iron in the Ross Sea Polynya in early summer

    NARCIS (Netherlands)

    Gerringa, L. J. A.; Laan, P.; van Dijken, G. L.; van Haren, H.; De Baar, H. J. W.; Arrigo, K. R.; Alderkamp, A. -C.

    2015-01-01

    Dissolved Fe (DFe) was measured in the Ross Sea Polynya (RSP), Antarctica, during a GEOTRACES cruise between 20 December 2013 and 5 January 2014. DFe was measured over the full water column with special emphasis on samples near the seafloor. In the upper mixed layer, DFe was very low everywhere (

  20. Overflow dynamics and bottom water formation in the western Ross Sea: Influence of tides

    Science.gov (United States)

    Wang, Q.; Danilov, S.; Hellmer, H. H.; SchröTer, J.

    2010-10-01

    The tidal impact on overflow dynamics and bottom water production in the western Ross Sea is studied with the Finite Element Ocean Model, which allows embedding a mesh with 0.5 km resolution in a coarse resolution (30 km) setup without nesting. The simulated overflow properties inside and downstream of the western Ross Sea are described. The overflow exhibits pronounced variability at both daily and spring-neap tidal time scales in the western Ross Sea. Tides increase mixing over both the outer shelf and upper slope there. Plume jets are shaped by tidal currents at a bathymetric bend west of the Drygalski Trough mouth, descending rapidly and supplying the bottom water. A fraction of shelf water remains over the shelf and propagates westward from the Ross Sea, but it does not contribute significantly to bottom water formation because of energetic mixing over the upper slope. Compared to a simulation without tidal forcing, tides (with the major K1 and O1 constituents) increase the outflow rate over the continental slope off Cape Adare by about 70%. A set of sensitivity experiments show that the rate of bottom water production is not a monotonic function of the tidal currents amplitude. Tidal forcing with intermediate strength leads to the most efficient bottom water formation.

  1. Deuterium excess as a proxy for sea ice extent in the western Ross Sea, Antarctica, 1882-2006

    Science.gov (United States)

    Sinclair, K. E.; Bertler, N.; Zwartz, D.; Trompetter, B.; Millet, M.; Davy, P.

    2011-12-01

    Deuterium excess in a high-resolution ice core extracted from the Whitehall Glacier (WHG) is highly sensitive to sea ice extent since observations began in 1979. Seasonal sea ice extent has increased significantly in the Ross Sea since 1995, creating a dipole between the Ross Sea and the Amundsen and Bellinghausen Sea Coasts, which have experienced significant sea ice loss. The reasons for the spatial differences in sea ice anomalies is thought to be primarily related to the phase of the Southern Annular Mode (SAM), the primary climate driver in this sector of Antarctica, and the complex interactions of SAM with the El Niño-Southern Oscillation (ENSO). A positive phase of SAM leads to deeper low pressure anomalies in the Amundsen Sea; cooler and stronger southerly winds in the western Ross Sea, and wind-driven sea ice advance, particularly when it is reinforced by La Nina conditions. In the WHG ice core, deuterium excess has mean values of 9.5 per mil from 1979 until 1994 and 5.2 per mil after 1995. This ~5 per mil shift is concurrent with a change from negative to positive sea ice extent anomalies in the Ross Sea and a concurrent decrease in marine trace elements (Na, Mg, V, Rb). We argue that increased southerly winds since 1995 (related to a more positive SAM) have increased the area of the Ross Sea and Terra Nova Bay polynas resulting in increased sea ice extent. Because sea surface temperatures (SST) are very low over these polynas, particularly in the austral autumn and winter, the deuterium excess signal at the Whitehall Glacier is highly sensitive to the amount of local moisture input and the seasonality of this moisture contribution. Increased local moisture, with low SST, results in low deuterium excess and therefore an inverse relationship with sea ice extent. In the context of the 125-year span of the WHG record, (1882-2006), deuterium excess is markedly high (and sea ice coverage is therefore expected to have been anomalously low) in the 1950s, '60s

  2. Distribution and ventilation of water masses in the western Ross Sea inferred from CFC measurements

    Science.gov (United States)

    Rivaro, Paola; Ianni, Carmela; Magi, Emanuele; Massolo, Serena; Budillon, Giorgio; Smethie, William M.

    2015-03-01

    During the CLIMA Project (R.V. Italica cruise PNRA XVI, January-February 2001), hydrographic and chlorofluorocarbons (CFCs) observations were obtained, particularly in the western Ross Sea. Their distribution demonstrated water mass structure and ventilation processes in the investigated areas. In the surface waters (AASW) the CFC saturation levels varied spatially: CFCs were undersaturated in all the areas (range from 80 to 90%), with the exception of few stations sampled near Ross Island. In particular, the Terra Nova Bay polynya, where high salinity shelf water (HSSW) is produced, was a low-saturated surface area (74%) with respect to CFCs. Throughout most of the shelf area, the presence of modified circumpolar deep water (MCDW) was reflected in a mid-depth CFC concentration minima. Beneath the MCDW, CFC concentrations generally increased in the shelf waters towards the seafloor. We estimated that the corresponding CFCs saturation level in the source water region for HSSW was about 68-70%. Waters with high CFC concentrations were detected in the western Ross Sea on the down slope side of the Drygalski Trough, indicating that AABW was being supplied to the deep Antarctic Basin. Estimates of ventilation ages depend strongly on the saturation levels. We calculated ventilation ages using the saturation level calibrated tracer ratio, CFC11/CFC12. We deduced a mean residence time of the shelf waters of about 6-7 years between the western Ross Sea source and the shelf break.

  3. Physical, chemical, and biological data collected during two research cruises in the Ross Sea, Antarctica from December 2004 to January 2005 and October to November 2005 for Ross Sea Sulfur Dynamics study (NODC Accession 0117322)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains transect data from two research cruises to the Ross Sea, Antarctica, aboard the RV Nathaniel B. Palmer (NBP) in December 2004 to January 2005...

  4. Subglacial Lake Whillans, West Antarctica; Solute Dynamics and Fluxes to the Ross Sea

    Science.gov (United States)

    Skidmore, M. L.; Michaud, A. B.; Achberger, A.; Barbante, C.; Christner, B. C.; Mikucki, J.; Mitchell, A. C.; Priscu, J. C.; Purcell, A. M.; van Gelder, W.; Vick-Majors, T.

    2014-12-01

    Subglacial Lake Whillans is located beneath the Whillans Ice Stream in West Antarctica. The lake is situated beneath 800 m of ice and ~ 70 km upstream of the grounding line where Whillans Ice Stream terminates into the Ross Sea. Subglacial Lake Whillans is a shallow lake and a component of a complex subglacial hydrological system that may resemble a large wetland along the Siple Coast of West Antarctica. Subglacial Lake Whillans drains and refills on a sub-decadal time scale discharging water towards the Ross Sea. Water and sediment samples were recovered from the lake, using clean access drilling technologies, in January, 2013. Isotopic analysis of the lake waters indicates basal meltwater from the ice sheet as the dominant water source. Geochemical analysis of the lake water reveals it is freshwater with mineral weathering as a significant solute source, with a minor contribution from sea water likely from relict marine sediments. Subglacial hydrothermal activity upstream may also contribute solutes. Nutrients N and P are present at micromolar concentrations. Sediment porewaters from shallow cores (~ 40 cm depth) of the subglacial lake sediments indicate increasing solute concentration with depth, with up to ~ five times greater solute concentrations than in the lake water. The waters and sediment contain metabolically active organisms which are likely involved in elemental cycling within the lake system. Here we will discuss solute sources to the lake, solute dynamics within the lake waters and sediment, and the fluxes of solute and nutrients to the Ross Sea and their implications for these marine ecosystems.

  5. Temperature, salinity and oxygen data collected from the Oden in the Amundsen and Ross Seas, 2010 - 2011 (NODC Accession 0104260)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data were collected to investigate the physical oceanography of the Amundsen and Ross Seas. Funded under the following projects: Physical Oceanography of the...

  6. 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.

  7. On the dense water spreading off the Ross Sea shelf (Southern Ocean)

    Science.gov (United States)

    Budillon, G.; Gremes Cordero, S.; Salusti, E.

    2002-07-01

    In this study, current meter and hydrological data obtained during the X Italian Expedition in the Ross Sea (CLIMA Project) are analyzed. Our data show a nice agreement with previous data referring to the water masses present in this area and their dynamics. Here, they are used to further analyze the mixing and deepening processes of Deep Ice Shelf Water (DISW) over the northern shelf break of the Ross Sea. In more detail, our work is focused on the elementary mechanisms that are the most efficient in removing dense water from the shelf: either classical mixing effects or density currents that interact with some topographic irregularity in order to drop to deeper levels, or also the variability of the Antarctic Circumpolar Current (ACC) which, in its meandering, can push the dense water off the shelf, thus interrupting its geostrophic flow. We also discuss in detail the (partial) evidence of dramatic interactions of the dense water with bottom particulate, of geological or biological origin, thus generating impulsive or quasi-steady density-turbidity currents. This complex interaction allows one to consider bottom particular and dense water as a unique self-interacting system. In synthesis, this is a first tentative analysis of the effect of bottom particulate on the dense water dynamics in the Ross Sea.

  8. Collaborative Research and Education in the Ross Sea: A broader impact evaluation report

    Science.gov (United States)

    Parsons, C.; Kohut, J. T.; Lichtenwalner, C. S.; Clark, H.

    2010-12-01

    An interdisciplinary team of researchers will focus on describing the high productivity patchiness observed in phytoplankton blooms in the mid-to-late summer in the Ross Sea, Antarctica. They will use a novel sampling strategy that employs a remotely controlled glider (AUV) to locate and map circumpolar deep water in near real time and also to direct further ship-based sampling. This unusual coordination of a polar research vessel with AUVs provides an exciting opportunity to engage formal and informal educators in a research adventure. As part of this NSF-funded project’s Criterion 2 broader impact, joining the researchers virtually will be 30 New Jersey middle-school teachers and their students. This summer in New Jersey, in partnership with Liberty Science Center educators, COSEE-NOW (Centers for Ocean Sciences Education Excellence-Networked Ocean World) and Woods Hole Oceanographic Institution, the project team introduced teachers to the Ross Sea, the research, the science behind it and the AUV. The summer workshop and ongoing schoolyear support is providing the teachers with the tools they need to bring the excitement of the research into their classrooms in real time during the Ross Sea cruise at the end of this year. This presentation by Chris Parsons, the project evaluator, will summarize the evaluation plan for this broader impact project, which follows teachers and their classes for a year, and provide the latest evaluation results from this project.

  9. The effects of changing winds and temperatures on the oceanography of the Ross Sea in the 21st century

    Science.gov (United States)

    Smith, Walker O.; Dinniman, Michael S.; Hofmann, Eileen E.; Klinck, John M.

    2014-03-01

    The Ross Sea is critically important in regulating Antarctic sea ice and is biologically productive, which makes changes in the region's physical environment of global concern. We examined the effects of projected changes in atmospheric temperatures and winds on aspects of the ocean circulation likely important to primary production using a high-resolution sea ice-ocean-ice shelf model of the Ross Sea. The modeled summer sea-ice concentrations decreased by 56% by 2050 and 78% by 2100. The duration of shallow mixed layers over the continental shelf increased by 8.5 and 19.2 days in 2050 and 2100, and the mean summer mixed layer depths decreased by 12 and 44%. These results suggest that the annual phytoplankton production in the future will increase and become more diatomaceous. Other components of the Ross Sea food web will likely be severely disrupted, creating significant but unpredictable impacts on the ocean's most pristine ecosystem.

  10. Snow chemistry measurements on James Ross Island (Antarctic Peninsula) showing sea-salt aerosol modifications

    Energy Technology Data Exchange (ETDEWEB)

    Aristarain, A.J. [Instituto Antartico Argentino (Argentina). Lab. de Estratigrafia Glaciar y Geoquimica de la Nieve; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Mendoza (Argentina); Delmas, R.J. [Laboratoire de Glaciologie et Geophysique de l' Environnement du CNRS, St Martin d' Heres (France)

    2002-07-01

    The fractionation of atmospheric sea-salt has been investigated by glaciochemical analysis of the sea-salt deposited on the snow covering the small ice cap of James Ross Island, Antarctic Peninsula, at an elevation of 1640m. The data show that, generally, but not always, the sea-salt deposited at this location most likely originates directly from seawater, as is the case at lower latitudes. It is found that the original chemical composition of the sea-salt aerosol is significantly modified, in particular by the reaction of sea-salt particles in the atmosphere with acid species. A ternary diagram (sodium, chloride, sulfate) is used to enlighten the involved modification processes. The study points out the frequent formation of HCl in the regional atmosphere. (Author)

  11. Effects of physical constraints on the lability of POM during summer in the Ross Sea

    Science.gov (United States)

    Misic, Cristina; Covazzi Harriague, Anabella; Mangoni, Olga; Aulicino, Giuseppe; Castagno, Pasquale; Cotroneo, Yuri

    2017-02-01

    The 0-200 m surface layer of the Ross Sea was studied during summer 2014 to investigate the lability of the particulate organic matter (POM) in response to physical parameters. With the use of satellite information, we selected three zones, characterised by different physical setting: a northern offshore area, crossing the summer-polynya area of the Ross Sea (hereafter called ROME 1), a more coastal area next to the Terra Nova Bay polynya (ROME 2); a southern offshore area, towards the Ross Ice Shelf (ROME 3). Ice-maps showed that the seasonal ice retreat had already occurred in early December for most of the stations. Statistical analysis of the quantitative and qualitative characteristics of the POM pointed to significant differences between the stations, especially in the upper mixed layer (UML). A comparison with previous studies showed that the localised pulses of POM accumulation in the UML were similar to those recorded at the highly productive marginal ice zones, providing notable trophic support to the ecosystem. The UML, although rather thin and easily subjected to alterations, confirmed its pivotal role in the ecosystem dynamics. A POM quality favourable to consumers was highlighted at several stations in ROME 1 and ROME 3. Reduced trophic support was, instead, found in ROME 2. Limited POM consumption where deep-water formation takes place would increase the POM role in the transfer of C to the depths.

  12. Improved Bathymetry Resolution in the Ross Sea from Aerogravity and Magnetics: Examples from Operation IceBridge.

    Science.gov (United States)

    Tinto, K. J.; Cochran, J. R.; Bell, R. E.; Charles, K.; Burton, B.

    2014-12-01

    The Ross Ice Shelf, located in the embayment between East and West Antarctica, is one of the largest underexplored patches of ocean on the planet. Sediment cores show that the Ross Ice Shelf can disintegrate during some interglacial periods. The conditions required for sudden collapse are not well constrained. A key to understanding the dynamics and long-term stability of the Ross Ice Shelf system is having high-resolution constraints on its boundary conditions, including sea floor bathymetry. The sea floor under the Ross Ice Shelf has developed in response to both the tectonic development of the West Antarctic Rift and the glacial signature of the waxing and waning Antarctic Ice Sheets. A mixture of fabrics and orientations in its bathymetry reflect this complex development. However, present oceanographic models of water circulation under the ice are based on low-resolution bathymetric maps drawn from stations spaced 55 km apart obtained during the RIGGS project in the 1970s. In contrast, most of the bathymetry of the world's oceans has been mapped to approximately 15 km resolution from satellite altimetry and much higher resolution from acoustic surveys. Improvement of Ross Ice Shelf bathymetry can be achieved from combined analysis and inversion of gravity and magnetic data acquired from airborne surveys over the Ross Ice Shelf. Survey lines flown in 2013 by Operation IceBridge, with the Sander Geophysics Ltd AIRGrav system over the central and northern Ross Embayment provide a tenfold increase, to 5 km, of the along track resolution of bathymetry. Newly resolved bathymetric highs and lows have amplitudes of up to 200 km. Combining the gravity and magnetic surveys also reveals the differing geology across the embayment. Results from these surveys, including comparison with ship-based bathymetry data from the Ross Sea, demonstrate the value of gravity and magnetic surveys for mapping the bathymetry of the Ross Ice Shelf and the need for more comprehensive

  13. Acoustic monitoring in the Ross Sea, Antarctica, using hydrophone of the Ocean Bottom Seismometer

    Science.gov (United States)

    Yun, Sukyoung; Lee, Won Sang; Kuk Hong, Jong; Yoo, Hyun Jae; Park, Yongcheol; Schmidt-Aursch, Mechita; Geissler, Wolfram H.

    2016-04-01

    Although a number of active source seismic experiments have been conducted over the last few decades to investigate the crustal structure in the Ross Sea, Antarctica, long-term observation to monitor underwater tectonic activities and changes in the cryospheric environment still remains challenging due to existence of sea ice in the study region. Korea Polar Research Institute has accomplished successful deployment of ocean bottom seismometers (OBS) in the Ross Sea collaborating with Alfred Wegener Institute during the period of 2011-2012 and 2014 by Korean icebreaker RV Araon. The OBS system manufactured by K.U.M. contains a hydrophone sensor that allow us to monitor underwater acoustics generated by tectonic and ice-related events. We present spectrograms of the continuous hydroacoustic data and various types of signals, e.g. seismic T-waves, iceequakes, and tremors. There are periodic and harmonic tremors that might be related with tidal modulation, and the seasonal variation of the background noise seems to be related with sea ice concentration.

  14. Analyses on Origin of positive gravity anomalies of sedimentary basins of the Ross Sea

    Science.gov (United States)

    Gao, Jinyao; Yang, Chunguo; Ji, Fei; Wang, Wei; Shen, Zhongyan

    2017-04-01

    We have adopted gridded products describing surface elevation, ice-thickness and the sea floor and subglacial bed elevation south of 60◦ S from Bedmap2 and north of 60◦ S from JGP95E to calculate Bouguer and isostatic gravity anomaly of the Ross Sea region based on the DTU10 free-air gravity anomaly.Taking a view of the free-air, Bouguer and isostatic gravity anomalies, it is unusual that high values overlay the Victoria Land Basin, Central Trough, Northern Basin and Northern Central Trough while basement highs are associated with low value. A number of studies have attributed the high gravity anomalies across the depocenters to high-density volcanics deep within the basins or magmatic intrusions within the region of the thinned crust or upper mantle (e. g., Edwards et al., 1987). According to the conclusion from Karner et al. (2005), the anticorrelation of gravity anomalies with sediment basement can be reproduced if the flexural strength of the lithosphere during the late Cretaceous rifting is significantly lower than the flexural strength of the lithosphere at the Oligocene and Neogene time of sedimentation. We note that the isostatic gravity anomalies are higher than the free-air gravity anomalies adjacent to the Transantarctic Mountains, and vice versa away from the Transantarctic Mountains. We may ignore the constraints offered by the tranditional isostasy in the local gravity studies of the Ross Sea basins, especially advancing the concept of high density material in the lower crust or upper mantle. In particular, the modeled gravity does not laterally integrate to zero, due to the existence of unbalanced forces induced by mantle. Along the outer shelf uplift zone surrouding Antarctica, the positive gravity belt has higher values in free-air gravity anomalies than those in isostatic gravity anomalies. Meanwhile, the positive gravity belt of isostatic gravity anomalies almost disappears in the background anomalies of 20 mGal to 10 mGal facing the

  15. Influence of coupling on atmosphere, sea ice and ocean regional models in the Ross Sea sector, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Jourdain, Nicolas C. [LGGE, UMR 5183, CNRS-UJF, Grenoble (France); LEGI, UMR 5519, CNRS-UJF-INPG, Grenoble (France); Mathiot, Pierre; Barnier, Bernard [LEGI, UMR 5519, CNRS-UJF-INPG, Grenoble (France); Gallee, Hubert [LGGE, UMR 5183, CNRS-UJF, Grenoble (France)

    2011-04-15

    Air-sea ice-ocean interactions in the Ross Sea sector form dense waters that feed the global thermohaline circulation. In this paper, we develop the new limited-area ocean-sea ice-atmosphere coupled model TANGO to simulate the Ross Sea sector. TANGO is built up by coupling the atmospheric limited-area model MAR to a regional configuration of the ocean-sea ice model NEMO. A method is then developed to identify the mechanisms by which local coupling affects the simulations. TANGO is shown to simulate realistic sea ice properties and atmospheric surface temperatures. These skills are mostly related to the skills of the stand alone atmospheric and oceanic models used to build TANGO. Nonetheless, air temperatures over ocean and winter sea ice thickness are found to be slightly improved in coupled simulations as compared to standard stand alone ones. Local atmosphere ocean feedbacks over the open ocean are found to significantly influence ocean temperature and salinity. In a stand alone ocean configuration, the dry and cold air produces an ocean cooling through sensible and latent heat loss. In a coupled configuration, the atmosphere is in turn moistened and warmed by the ocean; sensible and latent heat loss is therefore reduced as compared to the stand alone simulations. The atmosphere is found to be less sensitive to local feedbacks than the ocean. Effects of local feedbacks are increased in the coastal area because of the presence of sea ice. It is suggested that slow heat conduction within sea ice could amplify the feedbacks. These local feedbacks result in less sea ice production in polynyas in coupled mode, with a subsequent reduction in deep water formation. (orig.)

  16. Distribution of total alkalinity and pH in the Ross Sea (Antarctica waters during austral summer 2008

    Directory of Open Access Journals (Sweden)

    Paola Rivaro

    2014-10-01

    Full Text Available Measurements of total alkalinity (AT and pH were made in the Ross Sea in January–February 2008 in order to characterize the carbonate system in the Ross Sea and to evaluate the variability associated with different water masses. The main water masses of the Ross Sea, Antarctic Surface Water, High Salinity Shelf Water (HSSW, Deep Ice Shelf Water, Circumpolar Deep Water (CDW and Antarctic Bottom Water, were identified on the basis of the physical and chemical data. In particular, the AT ranged between 2275 and 2374 µmol kg−1 with the lowest values in the surface waters (2275–2346 µmol kg−1, where the influence of the sea-ice melting and of the variability of the physical properties was significant. In the deep layers of the water column, the AT maxima were measured in correspondence to the preferential pathways of the spreading HSSW. The pH had variable values in the surface layer (7.890–8.033 with the highest values in Terra Nova Bay and Ross Sea polynyas. A low pH (7.969±0.025 traced the intrusion of the CDW in the Ross Sea shelf area. All samples revealed waters that were oversaturated with respect to both calcite and aragonite, but near corrosive levels of aragonite saturation state (Ω ca. 1.1–1.2 were associated with the entrainment of CDW over the slope. Aragonite undersaturation is of particular concern for the zooplankton species comprising to calcifying organisms such as pteropods. The partial pressure of CO2 at the sea surface was undersaturated with respect to the atmospheric value, particularly in Terra Nova Bay and the Ross Sea polynyas, but a large variability in the sea–air CO2 fluxes was observed associated with different responses in the strength of the biological and physical processes.

  17. New age control on a mid-shelf grounding event in Eastern Basin, Ross Sea

    Science.gov (United States)

    Cone, A. N.; Bart, P. J.

    2009-12-01

    It is widely accepted that the West Antarctic Ice Sheet (WAIS) was grounded at the continental shelf edge in the eastern Ross Sea during the Last Glacial Maximum (LGM), but the precise chronology is debated. Post-LGM ice retreat chronologies have been developed using radiocarbon dating, mainly of acid-insoluble organics (AIO). Foraminifer tests yield more accurate radiocarbon dates than AIO because forams are less likely to be contaminated by allochthonous carbon, but unfortunately forams are sparse in Antarctic marine sediment cores. Here we show four consistent radiocarbon dates from forams in cored intervals within the foreset of a mid-continental-shelf grounding-zone wedge in Eastern Basin, Ross Sea. Our new radiocarbon dates reveal that the WAIS was grounded on the mid continental shelf circa 32,000 14C yr B.P., suggesting that retreat from this position began more than 10,000 years prior to the maximum sea level fall and global cooling associated with LGM. The dates contradict previous studies, which concluded that the WAIS was at its maximum shelf edge extent during LGM.

  18. Climate change impacts on southern Ross Sea phytoplankton composition, productivity, and export

    Science.gov (United States)

    Kaufman, Daniel E.; Friedrichs, Marjorie A. M.; Smith, Walker O.; Hofmann, Eileen E.; Dinniman, Michael S.; Hemmings, John C. P.

    2017-03-01

    The Ross Sea, a highly productive region of the Southern Ocean, is expected to experience warming during the next century along with reduced summer sea ice concentrations and shallower mixed layers. This study investigates how these climatic changes may alter phytoplankton assemblage composition, primary productivity, and export. Glider measurements are used to force a one-dimensional biogeochemical model, which includes diatoms and both solitary and colonial forms of Phaeocystis antarctica. Model performance is evaluated with glider observations, and experiments are conducted using projections of physical drivers for mid-21st and late-21st century. These scenarios reveal a 5% increase in primary productivity by midcentury and 14% by late-century and a proportional increase in carbon export, which remains approximately 18% of primary production. In addition, scenario results indicate diatom biomass increases while P. antarctica biomass decreases in the first half of the 21st century. In the second half of the century, diatom biomass remains relatively constant and P. antarctica biomass increases. Additional scenarios examining the independent contributions of expected future changes (temperature, mixed layer depth, irradiance, and surface iron inputs from melting ice) demonstrate that earlier availability of low light due to reduction of sea ice early in the growing season is the primary driver of productivity increases over the next century; shallower mixed layer depths additionally contribute to changes of assemblage composition and export. This study further demonstrates how glider data can be effectively used to facilitate model development and simulation, and inform interpretation of biogeochemical observations in the context of climate change.Plain Language SummaryUnderstanding how the global ocean responds to climate change requires knowing the natural behavior of individual regions and anticipating how future changes will affect each region differently. It

  19. Diet and trophic niche of Antarctic silverfish Pleuragramma antarcticum in the Ross Sea, Antarctica.

    Science.gov (United States)

    Pinkerton, M H; Forman, J; Bury, S J; Brown, J; Horn, P; O'Driscoll, R L

    2013-01-01

    The diet of Antarctic silverfish Pleuragramma antarcticum was evaluated by examining stomach contents of specimens collected in the Ross Sea (71°-77° S; 165°-180° E) in January to March 2008. Pleuragramma antarcticum (50-236 mm standard length, L(S)) and prey items were analysed for stable-isotopic composition of carbon and nitrogen. According to index of relative importance (I(RI) ), which incorporates frequency of occurrence, mass and number of prey items, the most important prey items were copepods (81%I(RI) over all specimens), predominantly Metridia gerlachei and Paraeuchaeta sp., with krill and fishes having low I(RI) (2·2 and 5·6%I(RI) overall). According to mass of prey (M) in stomachs, however, fishes (P. antarcticum and myctophids) and krill dominated overall diet (48 and 22%M, respectively), with copepods being a relatively minor constituent of overall diet by mass (9·9%M). Piscivory by P. antarcticum occurred mainly in the extreme south-west of the region and near the continental slope. Krill identified to species level in P. antarcticum stomachs were predominantly Euphausia superba (14·1%M) with some Euphausia crystallophorias (4·8%M). Both DistLM modelling (PRIMER-permanova+) on stomach contents (by I(RI)) and stepwise generalized linear modelling on stable isotopes showed that L(S) and location were significant predictors of P. antarcticum diet. Postlarval P. antarcticum (50-89 mm L(S)) consumed exclusively copepods. Juvenile P. antarcticum (90-151 mm L(S)) consumed predominantly krill and copepods by mass (46 and 30%M, respectively). Small adult P. antarcticum (152-178 mm L(S)) consumed krill, fishes and copepods (37, 36 and 15%M, respectively). Large adult P. antarcticum (179-236 mm L(S)) consumed predominantly fishes and krill (55 and 17%M, respectively), especially in the north (near the Ross Sea slope) and in the SW Ross Sea. Amphipods were occasionally important prey items for P. antarcticum (western Ross Sea, 39%M). General

  20. The Xanthophyceae and Chlorophyceae of the Western Ross Sea, Victoria Land, Antarctica and Macquarie Island collected under the direction of Prof. Dr. J. S. Zaneveld (1963—1967)

    NARCIS (Netherlands)

    Wagner, H.P.; Zaneveld, J.S.

    1988-01-01

    During the austral summer seasons of 1963-1964 and 1964-1965, and during the austral winter season of 1967 Prof. Dr. J.S. Zaneveld made collection expeditions to the western Ross Sea. In 1965 collections were also made from the U.S.C.G. icebreaker ‘Glacier’, around the western Ross Sea and around th

  1. Skeletal and isotopic composition and paleoclimatic significance of late Pleistocene carbonates, Ross Sea, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Taviani, M. (Ist. per la Geologia Marina, Bologna (Italy)); Reid, D.E.; Anderson, J.B. (Rice Univ., Houston, TX (United States))

    1993-01-01

    Carbonates cover an extensive area of the northwestern Ross Sea continental shelf. Radiocarbon dates yield late Pleistocene (stage 3) ages for these deposits, hence the carbonates appear to be correlative with widespread tills and glacial marine deposits in the region. Four carbonate facies are recognized on the basis of skeletal composition: a barnacle/foraminifer facies, a muddy bryozoan facies, a bryozoan/barnacle/pelecypod/foraminifer facies, and a planktonic foraminiferal facies. These deposits occur on the shelf and upper slope, while carbonate turbidities derived from them occur on the adjacent continental slope and rise. Compositional analyses of Ross Sea carbonates lend support to previously recognized criteria for identifying cold water carbonates. These include: (1) the presence of an associated ice-rafted component (including dropstones); (2) a dominance of calcite relative to other carbonate minerals (the remaining fraction consists solely of aragonite); (3) allochems that are entirely skeletal; and (4) heavy oxygen isotopic compositions (in the range of +3.0 to +5.1% PDB).

  2. Krill distribution in relation to environmental parameters in mesoscale structures in the Ross Sea

    Science.gov (United States)

    Leonori, Iole; De Felice, Andrea; Canduci, Giovanni; Costantini, Ilaria; Biagiotti, Ilaria; Giuliani, Giordano; Budillon, Giorgio

    2017-02-01

    Krill, a key pelagic resource of the Antarctic food web, provides an important link between primary and secondary plankton production and top predators. Since krill abundance is a crucial factor in Antarctic ecosystem functioning, its monitoring supplies vital data. Acoustic surveys are an effective approach to estimating krill abundance. An acoustic survey was conducted in the western Ross Sea in January 2014-10 years after a similar survey by our team - to estimate krill abundance and biomass and monitor oceanographic conditions. Antarctic krill (Euphausia superba) was detected in the northern part of the western Ross Sea and dense swarms of ice krill (Euphausia crystallorophias) were found in its central coastal area. Data analysis revealed an inverse correlation between E. superba density and salinity in the water column, whereas a positive correlation was found between E. crystallorophias abundance and fluorescence; the latter relationship was confirmed in thematic maps of E. crystallorophias spatial distribution and fluorescence. Comparison of 2004 and 2014 biomass data showed a much greater abundance of both species in the more recent survey.

  3. Ross Sea oceanographic data, 1983-1987 : USCGC Glacier, January-February 1983; USCGC Polar Sea, January-February 1984; USCGC Polar Star, February 1985; USCGC Polar Sea, February 1987 (NODC Accession 8900108)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and chemical data were collected using CTD casts from USCGC POLAR SEA and other platforms in the Ross Sea from 19 December 1976 to 06 February...

  4. Arctic Ocean sea ice drift origin derived from artificial radionuclides.

    Science.gov (United States)

    Cámara-Mor, P; Masqué, P; Garcia-Orellana, J; Cochran, J K; Mas, J L; Chamizo, E; Hanfland, C

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of (137)Cs and (239,240)Pu activities and the (240)Pu/(239)Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The (240)Pu/(239)Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the (240)Pu/(239)Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the (137)Cs and (239,240)Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  5. Late Wisconsin and early holocene glacial history, inner Ross Embayment, Antarctica

    Science.gov (United States)

    Denton, George H.; Bockheim, James G.; Wilson, Scott C.; Stuiver, Minze

    1991-01-01

    Lateral drift sheets of outlet glaciers that pass through the Transantarctic Mountains constrain past changes of the huge Ross ice drainage system of the Antarctic Ice Sheet. Drift stratigraphy suggests correlation of Reedy III (Reedy Glacier), Beardmore, Britannia (Hatherton/Darwin Glaciers), Ross Sea (McMurdo Sound), and younger (Terra Nova Bay) drifts; radiocarbon dates place the outer limits of Ross Sea drift in late Wisconsin time at 24,000 to 13,000 yr B.P. Outlet glacier profiles from these drifts constrain late Wisconsin ice sheet surface elevations. Within these constraint, two extreme late Wisconsin reconstructions are given of the Ross ice drainage system. Both show little elevation change of the polar plateau coincident with extensive ice shelf grounding along the inner Ross Embayment. However, in the central Ross Embayment, one reconstruction shows floating shelf ice, where as the other shows a grounded ice sheet. Massive late Wisconsin/Holocene recession of grounded ice from the western Ross Embayment, which was underway at 13,040 yr B.P. and completed by 6600 to 6020 yr B.P., was accompanied by little change in plateau ice levels inland of the Transantarctic Mountains.

  6. Ross Sea Polynyas: Response of Ice Concentration Retrievals to Large Areas of Thin Ice

    Science.gov (United States)

    Kwok, R.; Comiso, J. C.; Martin, S.; Drucker, R.

    2007-01-01

    For a 3-month period between May and July of 2005, we examine the response of the Advanced Microwave Scanning Radiometer (AMSR-E) Enhanced NASA Team 2 (NT2) and AMSR-E Bootstrap (ABA) ice concentration algorithms to large areas of thin ice of the Ross Sea polynyas. Coincident Envisat Synthetic Aperture Radar (SAR) coverage of the region during this period offers a detailed look at the development of the polynyas within several hundred kilometers of the ice front. The high-resolution imagery and derived ice motion fields show bands of polynya ice, covering up to approximately 105 km(sup 2) of the Ross Sea, that are associated with wind-forced advection. In this study, ice thickness from AMSR-E 36 GHz polarization information serves as the basis for examination of the response. The quality of the thickness of newly formed sea ice (<10 cm) from AMSR-E is first assessed with thickness estimates derived from ice surface temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The effect of large areas of thin ice in lowering the ice concentration estimates from both NT2/ABA approaches is clearly demonstrated. Results show relatively robust relationships between retrieved ice concentrations and thin ice thickness estimates that differ between the two algorithms. These relationships define the approximate spatial coincidence of ice concentration and thickness isopleths. Using the 83% (ABA) and 91% (NT2) isopleths as polynya boundaries, we show that the computed coverage compares well with that using the estimated 10-cm thickness contour. The thin ice response characterized here suggests that in regions with polynyas, the retrieval results could be used to provide useful geophysical information, namely thickness and coverage.

  7. An examination of the role of colonial Phaeocystis antarctica in the microbial food web of the Ross Sea

    Science.gov (United States)

    The extensive buildup of phytoplankton biomass in the Ross Sea conflicts with the view that high rates of herbivory occur in all regions of the Southern Ocean. Nano- and microplanktonic consumers comprise a significant fraction of total plankton biomass; however, the importance o...

  8. Iron limitation of a springtime bacterial and phytoplankton community in the Ross Sea: implications for vitamin B12 nutrition

    Directory of Open Access Journals (Sweden)

    Erin M. Bertrand

    2011-08-01

    Full Text Available The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early season Ross Sea phytoplankton community. The lack of B12 limitation in this location is consistent with previous Ross Sea studies in the austral summer, wherein vitamin additions did not stimulate P. antarctica growth and B12 was limiting only when bacterial abundance was low. Bottle incubation experiments and a bacterial regrowth experiment also revealed that iron addition directly enhanced bacterial growth. B12 uptake measurements in natural water samples and in an iron fertilized bottle incubation demonstrated that bacteria serve not only as a source for vitamin B12, but also as a significant sink, and that iron additions enhanced B12 uptake rates in phytoplankton but not bacteria. Additionally, vitamin uptake rates did not become saturated upon the addition of up to 95 pM B12. A rapid B12 uptake rate was observed after 13 min, which then decreased to a slower constant uptake rate over the next 52 hours. Results from this study highlight the importance of iron availability in limiting early season Ross Sea phytoplankton growth and suggest that rates of vitamin B12 production and consumption may be impacted by iron availability.

  9. Influence of submarine morphology on bottom water flow across the western Ross Sea continental margin

    Science.gov (United States)

    Davey, F.J.; Jacobs, S.S.

    2007-01-01

    Multibeam sonar bathymetry documents a lack of significant channels crossing outer continental shelf and slope of the western Ross Sea. This indicates that movement of bottom water across the shelf break into the deep ocean in this area is mainly by laminar or sheet flow. Subtle, ~20 m deep and up to 1000 m wide channels extend down the continental slope, into tributary drainage patterns on the upper rise, and then major erosional submarine canyons. These down-slope channels may have been formed by episodic pulses of rapid down slope water flow, some recorded on bottom current meters, or by sub-ice melt water erosion from an icesheet grounded at the margin. Narrow, mostly linear furrows on the continental shelf thought to be caused by iceberg scouring are randomly oriented, have widths generally less than 400 m and depths less than 30m, and extend to water depths in excess of 600 m.

  10. Evidence for the Late Cenozoic Antarctic Ice Sheet evolution and bottom current dynamics in the central-western Ross Sea outer margin, Antarctica

    Science.gov (United States)

    Kim, Sookwan; De Santis, Laura; Kuk Hong, Jong; Cottlerle, Diego; Petronio, Lorenzo; Colizza, Ester; Bergamasco, Andrea; Kim, Young-Gyun; Kang, Seung-Goo; Kim, Hyoungjun; Kim, Suhwan; Wardell, Nigel; Geletti, Riccardo; McKay, Robert; Jin, Young Keun; Kang, Sung-Ho

    2016-04-01

    Sedimentary records in polar continental margins provide clues for understanding paleo-depositional environments, related to ice sheet evolution and bottom-water current dynamics, during times of past climate and global sea level changes. Previous seismostratigraphic studies of the Ross Sea embayment, Antarctica, illustrated its general stratigraphic framework and the distribution of glacial sedimentary features over the continental shelf, since the onset of Antarctic ice-sheets at the Eocene-Oligocene boundary (~34.0 Ma). In contrast, there are a fewer studies for the outer continental margin, where continuous sedimentary deposits generally preserve the record of past climate cycles with minimum hiatus, comparing to the inner- and mid-continental shelf, where grounding ice streams eroded most of the sediments. Here we present a seismostratigraphic analysis of 2-D multichannel seismic reflection profiles, from the Central Basin located in the central-western Ross Sea outer margin. A glacial prograding wedge developed at the mouth of the Joides Basin since early-middle Miocene times (RSU4: ~14.0 Ma). And the Central Basin was filled with stacked debris-flow deposits and turbidites. The sediment depocenter shifted from the Central Basin toward the slope in the Pliocene (after RSU2: ~3.3 Ma). Pliocene foreset beds are steep and pinch out at the base of the continental slope. Bottom current controlled sediment drifts well developed since the middle Miocene, along the western slope of the central Basin and on the basement highs These areas are far from the mouth of the Joides trough, where most of the glacial sediment is deposited, and they are also more elevated than the basinal areas, where gravity flow maximum thickness accumulated. Along the western slope of the central Basin and over the basement highs, the signature in the sediments of the action of bottom current reworking and shaping the sea floor can be then clearly recognized. We present the sediment drifts

  11. Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA

    Science.gov (United States)

    Rainsford, A.; Soave, K.; Costolo, R.; Kudler, J.; Emunah, M.; Hatfield, J.; Kiyasu, J.

    2015-12-01

    Alina Rainsford, Kathy Soave, Julia Kudler, Jane Hatfield, Melea Emunah, Rose Costelo, Jenna Kiyasu, Amy Dean and Sustainable Seas Monitoring Project, Branson School, Ross, CA, United States, Farallones Marine Sanctuary Association, San Francisco, CA, United StatesAbstract:The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Each fall student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within two permanent 200 m2 areas, in fall, winter, and late spring. Using data from the previous years, we will compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis, Anthopluera elegantissima, Cladophora sp. and Fucus sp.. Future analyses and investigations will include intertidal abiotic factors (including water temperature, pH and human foot-traffic) to enhance insights into the Duxbury Reef ecosystem, in particular, the high

  12. Temporal variability of the Circumpolar Deep Water inflow onto the Ross Sea continental shelf

    Science.gov (United States)

    Castagno, Pasquale; Falco, Pierpaolo; Dinniman, Michael S.; Spezie, Giancarlo; Budillon, Giorgio

    2017-02-01

    The intrusion of Circumpolar Deep Water (CDW) is the primary source of heat, salt and nutrients onto Antarctica's continental shelves and plays a major role in the shelf physical and biological processes. Different studies have analyzed the processes responsible for the transport of CDW across the Ross Sea shelf break, but until now, there are no continuous observations that investigate the timing of the intrusions. Also, few works have focused on the effect of the tides that control these intrusions. In the Ross Sea, the CDW intrudes onto the shelf in several locations, but mostly along the troughs. We use hydrographic observations and a mooring placed on the outer shelf in the middle of the Drygalski Trough in order to characterize the spatial and temporal variability of CDW inflow onto the shelf. Our data span from 2004 to the beginning of 2014. In the Drygalski Trough, the CDW enters as a 150 m thick layer between 250 and 400 m, and moves upward towards the south. At the mooring location, about 50 km from the shelf break, two main CDW cores can be observed: one on the east side of the trough spreading along the west slope of Mawson Bank from about 200 m to the bottom and the other one in the central-west side from 200 m to about 350 m depth. A signature of this lighter and relatively warm water is detected by the instruments on the mooring at bottom of the Drygalski Trough. High frequency periodic CDW intrusion at the bottom of the trough is related to the diurnal and spring/neap tidal cycles. At lower frequency, a seasonal variability of the CDW intrusion is noticed. A strong inflow of CDW is observed every year at the end of December, while the CDW inflow is at its seasonal minimum during the beginning of the austral fall. In addition an interannual variability is also evident. A change of the CDW intrusion before and after 2010 is observed.

  13. The nepheloid bottom layer and water masses at the shelf break of the western Ross Sea

    Science.gov (United States)

    Capello, Marco; Budillon, Giorgio; Cutroneo, Laura; Tucci, Sergio

    2009-06-01

    In the austral summers of 2000/2001 and 2002/2003 the Italian CLIMA Project carried out two oceanographic cruises along the northwestern margin of the Ross Sea, where the Antarctic Bottom Water forms. Here there is an interaction between the water masses on the sea floor of the outer shelf and slope with a consequent evolution of benthic nepheloid layers and an increase in total particulate matter. We observed three different situations: (a) the presence of triads (bottom structures characterized by a concomitant jump in turbidity, temperature, and salinity data) and high re-suspension phenomena related to the presence of the Circumpolar Deep Water and its mixing with cold, salty shelf waters associated with gravity currents; (b) the absence of triads with high re-suspension, implying that when the gravity currents are no longer active the benthic nepheloid layer may persist until the suspended particles settle to the sea floor, suggesting that the turbidity data can be used to study recent gravity current events; and (c) the absence of turbidity and sediment re-suspension phenomena supports the theory that a steady situation had been re-established and the current interaction no longer occurred or had finished sometime before.

  14. Cenozoic geodynamics of the Ross Sea region, Antarctica: Crustal extension, intraplate strike-slip faulting, and tectonic inheritance

    Science.gov (United States)

    Salvini, Francesco; Brancolini, Giuliano; Busetti, Martina; Storti, Fabrizio; Mazzarini, Francesco; Coren, Franco

    1997-11-01

    An integrated study of onshore and offshore geology of the Ross Sea region (namely, Victoria Land, north of Ross Island, and the Ross Sea, Antarctica) has revealed a complex, post-Eocene tectonic framework. Regional NW-SE right-lateral, strike-slip faults are the outstanding feature of this framework and overprint an older Mesozoic extensional event, responsible for formation of N-S basins in the Ross Sea. The Cenozoic framework includes kinematic deformation and reactivation along the NW-SE faults, including formation of pull-apart basins, both positive and negative flower structures, and push-up ridges. N-S extensional faults are well developed between NW-SE faults and indicate E-W extension during the Cenozoic, produced by the NW-SE right-lateral strike-slip motion together with regional crustal extension. NNW-SSE compression, induced by the right-lateral, strike-slip kinematics, is indicated by locally inverted NE-SW faults and basins. The evolution, geometry, and location of the Rennick Graben and the Lanterman Range fit well into this model. Variations in the deformational style across the region can be linked to corresponding variations in the bulk crustal rheology, from brittle behavior in the west, to ductile deformation (at subseismic-scale resolution) near the Eastern Basin. A semibrittle region that favors N-S clustering of Cenozoic magmatic activity lies in between. In this region, Cenozoic volcanoes develop at the intersections of the NW-SE and the major N-S faults. The NW-SE faults cut almost continually from the Ross Sea to East Antarctica through lithospheric sectors with different rheology and thickness. At least two of the NW-SE faults correspond to older Paleozoic terrane boundaries in northern Victoria Land. The NW-SE faults link in the Southern Ocean with major transform faults related to the plate motions of Australia, New Zealand, and Antarctica.

  15. Improved method for sea ice age computation based on combination of sea ice drift and concentration

    Science.gov (United States)

    Korosov, Anton; Rampal, Pierre; Lavergne, Thomas; Aaboe, Signe

    2017-04-01

    Sea Ice Age is one of the components of the Sea Ice ECV as defined by the Global Climate Observing System (GCOS) [WMO, 2015]. It is an important climate indicator describing the sea ice state in addition to sea ice concentration (SIC) and thickness (SIT). The amount of old/thick ice in the Arctic Ocean has been decreasing dramatically [Perovich et al. 2015]. Kwok et al. [2009] reported significant decline in the MYI share and consequent loss of thickness and therefore volume. Today, there is only one acknowledged sea ice age climate data record [Tschudi, et al. 2015], based on Maslanik et al. [2011] provided by National Snow and Ice Data Center (NSIDC) [http://nsidc.org/data/docs/daac/nsidc0611-sea-ice-age/]. The sea ice age algorithm [Fowler et al., 2004] is using satellite-derived ice drift for Lagrangian tracking of individual ice parcels (12-km grid cells) defined by areas of sea ice concentration > 15% [Maslanik et al., 2011], i.e. sea ice extent, according to the NASA Team algorithm [Cavalieri et al., 1984]. This approach has several drawbacks. (1) Using sea ice extent instead of sea ice concentration leads to overestimation of the amount of older ice. (2) The individual ice parcels are not advected uniformly over (long) time. This leads to undersampling in areas of consistent ice divergence. (3) The end product grid cells are assigned the age of the oldest ice parcel within that cell, and the frequency distribution of the ice age is not taken into account. In addition, the base sea ice drift product (https://nsidc.org/data/docs/daac/nsidc0116_icemotion.gd.html) is known to exhibit greatly reduced accuracy during the summer season [Sumata et al 2014, Szanyi, 2016] as it only relies on a combination of sea ice drifter trajectories and wind-driven "free-drift" motion during summer. This results in a significant overestimate of old-ice content, incorrect shape of the old-ice pack, and lack of information about the ice age distribution within the grid cells. We

  16. Arctic Ocean sea ice drift origin derived from artificial radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Camara-Mor, P., E-mail: patricia.camara@uab.es [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Masque, P. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Garcia-Orellana, J. [Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); Dpt. de Fisica, Universitat Autonoma de Barcelona, E-08193. Bellaterra (Spain); School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Cochran, J.K. [School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); Mas, J.L. [Dpto. de Fisica Aplicada, Universidad de Sevilla, 41012, Seville. Spain (Spain); Chamizo, E. [Centro Nacional de Aceleradores (CNA), Avd. Thomas Alva Edison 7, Isla de la Cartuja, E-41092, Seville (Spain); Hanfland, C. [Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven (Germany)

    2010-07-15

    Since the 1950s, nuclear weapon testing and releases from the nuclear industry have introduced anthropogenic radionuclides into the sea, and in many instances their ultimate fate are the bottom sediments. The Arctic Ocean is one of the most polluted in this respect, because, in addition to global fallout, it is impacted by regional fallout from nuclear weapon testing, and indirectly by releases from nuclear reprocessing facilities and nuclear accidents. Sea-ice formed in the shallow continental shelves incorporate sediments with variable concentrations of anthropogenic radionuclides that are transported through the Arctic Ocean and are finally released in the melting areas. In this work, we present the results of anthropogenic radionuclide analyses of sea-ice sediments (SIS) collected on five cruises from different Arctic regions and combine them with a database including prior measurements of these radionuclides in SIS. The distribution of {sup 137}Cs and {sup 239,240}Pu activities and the {sup 240}Pu/{sup 239}Pu atom ratio in SIS showed geographical differences, in agreement with the two main sea ice drift patterns derived from the mean field of sea-ice motion, the Transpolar Drift and Beaufort Gyre, with the Fram Strait as the main ablation area. A direct comparison of data measured in SIS samples against those reported for the potential source regions permits identification of the regions from which sea ice incorporates sediments. The {sup 240}Pu/{sup 239}Pu atom ratio in SIS may be used to discern the origin of sea ice from the Kara-Laptev Sea and the Alaskan shelf. However, if the {sup 240}Pu/{sup 239}Pu atom ratio is similar to global fallout, it does not provide a unique diagnostic indicator of the source area, and in such cases, the source of SIS can be constrained with a combination of the {sup 137}Cs and {sup 239,240}Pu activities. Therefore, these anthropogenic radionuclides can be used in many instances to determine the geographical source area of sea-ice.

  17. Miocene Antarctic ice dynamics in the Ross Embayment (Western Ross Sea, Antarctica): Insights from provenance analyses of sedimentary clasts in the AND-2A drill core

    Science.gov (United States)

    Cornamusini, Gianluca; Talarico, Franco M.

    2016-11-01

    A detailed study of gravel-size sedimentary clasts in the ANDRILL-2A (AND-2A) drill core reveals distinct changes in provenance and allows reconstructions to be produced of the paleo ice flow in the McMurdo Sound region (Ross Sea) from the Early Miocene to the Holocene. The sedimentary clasts in AND-2A are divided into seven distinct petrofacies. A comparison of these with potential source rocks from the Transantarctic Mountains and the coastal Southern Victoria Land suggests that the majority of the sedimentary clasts were derived from formations within the Devonian-Triassic Beacon Supergroup. The siliciclastic-carbonate petrofacies are similar to the fossiliferous erratics found in the Quaternary Moraine in the southern McMurdo Sound and were probably sourced from Eocene strata that are currently hidden beneath the Ross Ice Shelf. Intraformational clasts were almost certainly reworked from diamictite and mudstone sequences that were originally deposited proximal to the drill site. The distribution of sedimentary gravel clasts in AND-2A suggests that sedimentary sequences in the drill core were deposited under two main glacial scenarios: 1) a highly dynamic ice sheet that did not extend beyond the coastal margin and produced abundant debris-rich icebergs from outlet glaciers in the central Transantarctic Mountains and South Victoria Land; 2) and an ice sheet that extended well beyond the coastal margin and periodically advanced across the Ross Embayment. Glacial scenario 1 dominated the early to mid-Miocene (between ca. 1000 and 225 mbsf in AND-2A) and scenario 2 the early Miocene (between ca. 1138 and 1000 mbsf) and late Neogene to Holocene (above ca. 225 mbsf). This study augments previous research on the clast provenance and highlights the added value that sedimentary clasts offer in terms of reconstructing past glacial conditions from Antarctic drill core records.

  18. Water mass dynamics shape Ross Sea protist communities in mesopelagic and bathypelagic layers

    Science.gov (United States)

    Zoccarato, Luca; Pallavicini, Alberto; Cerino, Federica; Fonda Umani, Serena; Celussi, Mauro

    2016-12-01

    Deep-sea environments host the largest pool of microbes and represent the last largely unexplored and poorly known ecosystems on Earth. The Ross Sea is characterized by unique oceanographic dynamics and harbors several water masses deeply involved in cooling and ventilation of deep oceans. In this study the V9 region of the 18S rDNA was targeted and sequenced with the Ion Torrent high-throughput sequencing technology to unveil differences in protist communities (>2 μm) correlated with biogeochemical properties of the water masses. The analyzed samples were significantly different in terms of environmental parameters and community composition outlining significant structuring effects of temperature and salinity. Overall, Alveolata (especially Dinophyta), Stramenopiles and Excavata groups dominated mesopelagic and bathypelagic layers, and protist communities were shaped according to the biogeochemistry of the water masses (advection effect and mixing events). Newly-formed High Salinity Shelf Water (HSSW) was characterized by high relative abundance of phototrophic organisms that bloom at the surface during the austral summer. Oxygen-depleted Circumpolar Deep Water (CDW) showed higher abundance of Excavata, common bacterivores in deep water masses. At the shelf-break, Antarctic Bottom Water (AABW), formed by the entrainment of shelf waters in CDW, maintained the eukaryotic genetic signature typical of both parental water masses.

  19. A modelling study of the hydrographic structure of the Ross Sea

    Directory of Open Access Journals (Sweden)

    M. Tonelli

    2012-11-01

    Full Text Available Dense water formation around Antarctica is recognized as one of the most important processes to climate modulation, since that is where the linkage between the upper and lower limbs of Global Thermohaline Circulation takes place. Assessing whether these processes may be affected by rapid climate changes and all the related feedbacks may be crucial to fully understand the ocean heat transport and to provide future projections. Applying the Coordinated Ocean-Ice Reference (CORE normal year forcing we have run a 100-yr simulation using Regional Ocean Model System (ROMS with explicit sea-ice/ice-shelf thermodynamics. The normal year consists of single annual cycle of all the data that are representative of climatological conditions over decades and can be applied repeatedly for as many years of model integration as necessary. The experiment employed a circumpolar variable resolution (1/2° to 1/24° grid reaching less than 5 km over the inner continental shelf. With Optimum Parameter Analysis (OMP the main Ross Sea (RS water masses are identified: Antarctic surface water (AASW, circumpolar deep water (CDW, shelf water (SW and ice shelf water (ISW. Current configuration allows very realistic representation, where results compare extremely well to the observations.

  20. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica

    Directory of Open Access Journals (Sweden)

    Pietro Tedesco

    2016-04-01

    Full Text Available Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc. Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL and unreported antimicrobial activity against Bcc strains.

  1. Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica) †

    Science.gov (United States)

    Tedesco, Pietro; Maida, Isabel; Palma Esposito, Fortunato; Tortorella, Emiliana; Subko, Karolina; Ezeofor, Chidinma Christiana; Zhang, Ying; Tabudravu, Jioji; Jaspars, Marcel; Fani, Renato; de Pascale, Donatella

    2016-01-01

    Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains. PMID:27128927

  2. Preliminary data on formaldehyde content in seawater samples from Terra Nova Bay (Ross Sea - Antarctica)

    Science.gov (United States)

    Largiuni, O.; Becagli, S.; Traversi, R.; Udisti, R.

    2003-04-01

    Formaldehyde is a key reactive intermediate in the methane oxidation chain. To date, only a few measurements of HCHO in surface seawater have been reported, suggesting a net flux of HCHO from the atmosphere to the ocean surface. Ocean is considered as a sink for atmospheric HCHO, but it cannot be excluded that marine areas characterized by high biogenic activity constitute a source of HCHO to atmosphere. Indeed, laboratory experiments carried out on seawater microlayer show HCHO production by photo-oxidation of dissolved organic matter. To date no measurements on deep seawater samples were performed. A sensitive method for the formaldehyde determination in aqueous sample by Flow Injection Analysis has been applied to seawater samples analysis. The method has a detection limit of 55 ng/l and a reproducibility of 2.5% at 1 ug/l level (5 % in sea water samples). The detector response is linear in the range 0.1 - 3000 ug/l. In the framework of the Italian Research Programme in Antarctica (PNRA), 20 samples were collected in two stations in the Gerlache Inlet (Terra Nova Bay, Western Ross Sea) during the 2001/2002 field campaign (November 2001 to February 2002). The samples were collected through a hole in the sea-ice, along the water column, using a Go-Flo type bottle. Usually, just sub-pack and 30 and 50 m depth fractions were collected. For each depth profile, temperature, salinity and chlorophyll fluorescence signal were measured. Formaldehyde concentrations range from 4.5 to 40 ppb. The relationship between HCHO content and other measured parameters is discussed. The sampling repetition in time at the same sites allowed evaluating the seasonal changes in the formaldehyde concentration/depth profiles.

  3. Detrital dating on drill-core records from McMurdo Sound, Ross Sea (Antarctica)

    Science.gov (United States)

    Zattin, M.; Andreucci, B.; Balestrieri, M.; Olivetti, V.; Pace, D.; Reiners, P. W.; Rossetti, F.; Talarico, F.; Thomson, S. N.

    2012-12-01

    The influence of Antarctic ice sheets on the global climate system during the Cenozoic has been intensely investigated in the last years, especially after the successful drilling projects off-shore the western Ross Sea. While the role of the Western Ice Sheet (WAIS) during the Miocene it is not clear, the East Antarctic Ice Sheet (EAIS) has been suggested to be more or less stable and cold for the last 14 Ma. Records from drilling projects in syn-tectonic basins located on the continental shelf along the western margin of the West Antarctica Rift System (DSDP, CIROS, CRP and ANDRILL projects) may provide crucial information on the tectonic and paleo-climatic evolution of that region during Cenozoic. The drilled sedimentary records have been therefore investigated by detrital geochronology which, integrated by sandstone and gravel petrography, can provide valuable information on the dynamics of the ice sheets as provenance data are sensitive to variations in the ice-flow patterns. Apatite fission-track (AFT) data from ANDRILL and CRP records show multiple peaks in most of the samples. In the AND-2A well, whose stratigraphic record spans the last 20 Ma, the grain-age distributions are dominated by grains between 20 and 40 Ma. A young peak with a comparable age has been also episodically detected in CRP wells where conversely the most relevant population is made by grain ages between 45 and 70 Ma. Samples from Late Miocene-Pleistocene sediments of AND-1B well show a completely different AFT age distribution as a single peak is usually detected and ages are younger than 20 Ma. The AFT age range is well represented in bedrock data along the entire Transantarctic Mountains (TAM). The main denudation phase in the TAM began at 55-50 Ma but the occurrence of a young peak in the detrital data at ca. 35 Ma indicates the presence of an Oligocene pulse, as testified also by the small gap between AFT and some (U-Th-Sm)/He ages that have been detected on AND-2A samples. Such

  4. 40Ar-39Ar Age Constraints on Volcanism and Tectonism in the Terror Rift of the Ross Sea, Antarctica

    Science.gov (United States)

    2007-01-01

    Volcanic sills and dikes inferred from seismic reflection profiles and geophysical studies of the Ross Sea are thought to be related to the rift basins in the region, and their emplacement to be coeval with extension. However, lack of precise geochronology in the Terror Rift of the Ross Sea region has left these inferred relationships poorly constrained and has hindered neotectonic studies, because of the large temporal gaps between seismic reflectors of known ages. New 40Ar/39Ar geochronology presented here for submarine volcanic rocks provides better age constraints for neotectonic interpretations within the Terror Rift. Several samples from seamounts yielded young ages between 156 ± 21 and 122 ± 26 Ka. These ages support interpretations that extension within the Terror Rift was active at least through the Pleistocene. Three evenly spaced samples from the lowermost 100 m of Franklin Island range in age from 3.28 ± 0.04 to 3.73 ± 0.05 Ma. These age determinations demonstrate that construction of a small volcanic edifice such as Franklin Island took at least several hundred thousand years, and therefore that much larger ones in the Erebus Volcanic Province are likely to have taken considerably longer than previously inferred. This warrants caution in applying a limited number of age determinations to define the absolute ages of events in the Ross Sea region

  5. Biochemical and microbial features of shallow marine sediments along the Terra Nova Bay (Ross Sea, Antarctica)

    Science.gov (United States)

    Baldi, Franco; Marchetto, Davide; Pini, Francesco; Fani, Renato; Michaud, Luigi; Lo Giudice, Angelina; Berto, Daniela; Giani, Michele

    2010-09-01

    Shallow marine sediments were collected from seven stations (three of which located at Gerlache Inlet, two at Tethys Bay, one at Adelie Cove and one just beneath the Italian Research Base) along the Terra Nova Bay coast (Ross Sea, Antarctica). Their chemical, biochemical and microbiological properties were studied in order to provide further insights in the knowledge of this Antarctic benthic ecosystem. Overall, the organic carbon (OC) represented the major fraction of total carbon (TC) and displayed concentrations similar to or slightly lower than those previously measured in Antarctic bottom sediments. The biopolymeric carbon within OC ranged from 4.1% to 19.9% and showed a wide trophic range (65-834 μg g -1 d.w.). Proteins (PRT) represented on average the main biochemical class contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). The activity of aminopeptidase, β- D-glucosidase, alkaline phosphatase and esterase was checked, giving the highest values at Tethys Bay and at the deepest water sediments. The principal component analysis, which was computed considering physical, chemical (elemental and biochemical sedimentary composition) and microbiological parameters (including bacterial abundance, ectoenzymatic activities, T-RFs richness and diversity indices), allowed to obtain two main clusters ("Tethys Bay" and "other stations"). Based on data obtained, two representative 16S rRNA clone libraries using samples from Tethys Bay and Gerlache Inlet were constructed. The sequences of 171 clones were compared to those available in public databases to determine their approximate phylogenetic affiliations. Both aerobic and anaerobic bacteria were disclosed, with the majority of them affiliated with the Gamma- and Deltaproteobacteria, Bacteroidetes and Acidobacteria. The occurrence of strictly anaerobic bacteria suggests that sediments might also undergo anoxic conditions that, in turn, could favor the accumulation of PRT in respect

  6. Soluble Salt Accumulations in Taylor Valley, Antarctica: Implications for Paleolakes and Ross Sea Ice Sheet Dynamics

    Science.gov (United States)

    Toner, J. D.; Sletten, R. S.; Prentice, M. L.

    2012-12-01

    Soluble salt accumulations in Taylor Valley, Antarctica, provide a history of paleolakes and the advance of the Ross Sea Ice Sheet (RSIS). We measured soluble salts in 89 soils throughout Taylor Valley in soil-water extractions. In western Taylor Valley, soluble salt accumulations are relatively high and are comprised primarily of Na, Ca, Cl, and SO4. In eastern Taylor Valley, soluble salt accumulations are much lower and are comprised primarily of Na and HCO3. Salt compositions measured in soil-water extractions are highly influenced by the dissolution of sparingly soluble salts (e.g. calcite and gypsum) and cation exchange reactions. Furthermore, during soil-water extractions, Ca from calcite or gypsum dissolution exchanges with exchangeable Na, K, and Mg. These processes can strongly influence both the total salt content measured in soils and ionic ratios. Thus, it is important to consider the effects of these reactions when interpreting soluble salt accumulations measured in soil-water extractions. Calcite dissolution and cation exchange reactions also appear to have a widespread natural occurrence, resulting in the Na-HCO3 compositions of soils, streams, and lakes in eastern Taylor Valley. The soluble salt data supports the hypotheses that a lobe of the RSIS expanded into eastern Taylor Valley and dammed proglacial paleolakes. However, in contrast to previous studies, our findings indicate that the RSIS advanced deeper into Taylor Valley and that paleolakes were less extensive. By comparing soluble salt distributions across Taylor Valley, we conclude that a lobe of the RSIS filled all of eastern Taylor Valley and dammed paleolakes in western Taylor Valley up to 300 m elevation. Following ice retreat, smaller paleolakes formed in both western and eastern Taylor Valley up to about 120 m, with a prominent still stands at 80 m that was controlled by the elevation of a major valley threshold.

  7. West Antarctic Ice Sheet dynamics recorded in Plio-Pleistocene strata of the Ross Sea, Antarctica

    Science.gov (United States)

    Loth, A. S.; Bartek, L. R.; Luyendyk, B. P.; Wilson, D. S.

    2008-12-01

    Within the 100,000 square kilometer Eastern Basin of the Ross Sea, a 290 km section, oriented parallel to depostional dip along with 10 intersecting seismic sections that are oriented parallel to depositional strike were analyzed. Using Single-Channel Seismic (SCS) data from three different seismic surveys (NBP 0306, PD9022, and NBP 9308) 36 Plio-Pleistocene sequences were correlated across the basin from the modern ice shelf edge to the contemporary shelf break. Few of the sequences are continuous across the shelf, the majority of the sequences are of limited lateral extent. The facies within the sequences were analyzed to determine ice sheet behavior at the time of deposition. Three distinct depositional environments were interpreted based upon variations in the reflection attributes within the seismic data. Subglacial facies have a spectrum of reflection attributes from reflection-free to parallel, low-amplitude, discontinuous facies. The Grounding Line Zone facies are characterized by high amplitude, mildly discontinuous reflections. Proglacial environments are distinguished by parallel, high amplitude, continuous reflection packages. The facies distribution within many of the sequences consists of Subglacial facies in updip locales, Grounding Line Zone facies widely distributed across the shelf, and Proglacial facies present at downdip sites. The facies distribution within the sequences provides a record of the variation of the extent of the West Antarctic Ice Sheet (WAIS) throughout the Plio-Pleistocene. Not all sequences have a consecutive facies relationship, which may have resulted from several causes: 1) changes in the flow of the WAIS, 2) interplay between the East Antarctic Ice Sheet (EAIS) with the WAIS, or 3) additional grounding of the WAIS on paleobasin highs. Understanding the short-lived glacial events, whether they are a function of non-deposition or cannibalization of previous deposits, provides insight into the dynamics of marine based ice

  8. Radionuclides in ornithogenic sediments as evidence for recent warming in the Ross Sea region, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Yaguang [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei, Anhui 230031 (China); Xu, Liqiang [School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Liu, Xiaodong, E-mail: ycx@ustc.edu.cn [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Emslie, Steven D. [Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403 (United States)

    2016-07-01

    Radionuclides including {sup 210}Pb, {sup 226}Ra and {sup 137}Cs were analyzed in eight ornithogenic sediment profiles from McMurdo Sound, Ross Sea region, East Antarctica. Equilibration between {sup 210}Pb and {sup 226}Ra were reached in all eight profiles, enabling the determination of chronology within the past two centuries through the Constant Rate of Supply (CRS) model. Calculated fluxes of both {sup 210}Pb and {sup 137}Cs varied drastically among four of the profiles (MB4, MB6, CC and CL2), probably due to differences in their sedimentary environments. In addition, we found the flux data exhibiting a clear decreasing gradient in accordance with their average deposition rate, which was in turn related to the specific location of the profiles. We believe this phenomenon may correspond to global warming of the last century, since warming-induced surface runoff would bring more inflow water and detritus to the coring sites, thus enhancing the difference among the profiles. To verify this hypothesis, the deposition rate against age of the sediments was calculated based on their determined chronology, which showed ascending trends in all four profiles. The significant increase in deposition rates over the last century is probably attributable to recent warming, implying a potential utilization of radionuclides as environmental indicators in this region. - Highlights: • {sup 210}Pb, {sup 226}Ra and {sup 137}Cs were measured in ornithogenic sediment profiles. • Chronology within 200 years was determined through Constant Rate of Supply model. • Calculated nuclide fluxes decreased with average deposition rate and locations. • Deposition rate over time indicated warming which caused the flux gradient.

  9. Time-frequency analysis of migrating zooplankton in the Terra Nova Bay polynya (Ross Sea, Antarctica)

    Science.gov (United States)

    Picco, Paola; Schiano, M. Elisabetta; Pensieri, Sara; Bozzano, Roberto

    2017-02-01

    An upward-looking 150 kHz narrow-band Acoustic Doppler Current profiler was operated in Terra Nova Bay (Ross Sea, Antarctica) from 5 February 2000 to 16 January 2001 to monitor marine currents. The instrument sampled the upper 160 m of the water column with a time resolution of 1 h. Although the experimental setup was not specifically designed to assess zooplankton and fish distributions and behaviour, the Acoustic Doppler Current Profiler ancillary data provided useful information regarding the diel vertical migration of these acoustic targets. A time frequency analysis of the mean backscatter strength time series was conducted using a 240 h-wide window with a 1 day step. Assuming that the 24 h period peak is associated with zooplankton diel vertical migration, the amplitude of the power spectral energy on this band was extracted from each spectrum and the time series of amplitudes was analysed. The migration signal was very weak during summer, December to January, but was evident at the beginning and end of the polar night. Interestingly, the results indicated four "migratory blooms," the first at the end of August and the others approximately every three weeks subsequently, ending at the end of October. The daily migration was found to have a good relation with the solar cycle, while it was apparently uncorrelated with the moon phase. Migration patterns in the upper and the lower ocean layers displayed significant differences. Due to the lack of contemporary in-situ net samples, the results are more qualitative than quantitative; nonetheless, they demonstrate the validity of the method to extract relevant information even when applied to data obtained from a non-devoted low-resolution system. This may be of particular interest in polar areas where it is difficult to perform continuous biological monitoring but where a long time series of Acoustic Doppler Current profiler data is available.

  10. Photosynthesis-irradiance responses in the Ross Sea, Antarctica: a meta-analysis

    Science.gov (United States)

    Smith, W. O., Jr.; Donaldson, K.

    2015-06-01

    A meta-analysis of photosynthesis-irradiance measurements was completed using data from the Ross Sea, Antarctica, using a total of 417 independent measurements. PmB, the maximum, chlorophyll-specific, irradiance-saturated rate of photosynthesis, averaged 1.1 ± 0.06 μg C (μg Chl)-1 h-1. Light-limited, chlorophyll-specific photosynthetic rates (αB) averaged 0.030 ± 0.023 μg C (μg Chl)-1 h-1 (μmol quanta m-2 s-1)-1. Significant variations in PmB and αB were found as a function of season, with spring maximum photosynthetic rates being 60% greater than those in summer. Similarly, α values were 48% greater in spring. There was no detectable effect of sampling location on the photo-synthetic parameters, and temperature and macronutrient (NO3) concentrations also did not have an influence. However, irradiance and carbon dioxide concentrations, when altered under controlled conditions, exerted significant influences on photosynthetic parameters. Specifically, reduced irradiance resulted in significantly decreased PmB and increased αB values, and increased CO2 concentrations resulted in significantly increased PmB and αB values. Comparison of photosynthetic parameters derived at stations where iron concentrations were above and below 0.1 nM indicated that reduced iron levels were associated with significantly increased PmB values, confirming the importance of iron within the photosynthetic process. No significant difference was detected between stations dominated by diatoms and those dominated by the haptophyte Phaeocystis antarctica. The meta-analysis confirms the photosynthetic rates predicted from global analyses that are based solely on temperature and irradiance availability, but suggests that, for more accurate predictions of productivity in polar systems, a more detailed model that includes temporal effects of photosynthetic parameters will be required.

  11. Phytoplankton assemblages and lipid biomarkers indicate sea-surface warming and sea-ice decline in the Ross Sea during Marine Isotope sub-Stage 5e

    Science.gov (United States)

    Hartman, Julian D.; Sangiorgi, Francesca; Peterse, Francien; Barcena, Maria A.; Albertazzi, Sonia; Asioli, Alessandra; Giglio, Federico; Langone, Leonardo; Tateo, Fabio; Trincardi, Fabio

    2016-04-01

    The Marine Isotope sub-Stage 5e (~ 125 - 119 kyrs BP), the last interglacial period before the present, is believed to have been globally warmer (~ 2°C) than today. Studying this time interval might therefore provide insights into near future climate state given the ongoing climate change and global temperature increase. Of particular interest are the expected changes in polar ice cover. One important aspect of the cryosphere is sea-ice, which influences albedo, deep and surface water currents, and phytoplankton production, and thus affects the global climate system. To investigate whether changes in sea-ice cover occurred in the Southern Ocean close to Antarctica during Marine Isotope sub-Stage 5e dinoflagellate and diatom assemblages have been analyzed in core AS05-10, drilled in the continental slope off the Drygalski basin (Ross Sea) at a water depth of 2377 m. The core was drilled within the frame of the PNRA 2009/A2.01 project, an Italian project with a multidisciplinary approach, and covers the interval from Present to Marine Isotope Stage (MIS) 7. The core stratigraphy is based on diatom bioevents and on the climate cyclicity provided by the variations of the diatom assemblages. For this study we focused on the interval from MIS7 to MIS5. A strong reduction of sea-ice-loving diatom taxa with respect to open water-loving diatom taxa is observed during MIS5. In general the production of phytoplankton increases at the base of MIS5 and then slowly decreases. Dinoflagellate cysts, particularly heterotrophic species, are abundant during MIS5e only. The sea surface temperature reconstruction based on the TEX86L, a proxy based on lipid biomarkers produced by Thaumarcheota, shows a 4°C temperature increase from MIS6 to MIS5e. A slightly smaller temperature increase is observed at the onset of MIS7, but this stage is barren of heterotrophic dinoflagellates. All proxies together seem to indicate that the retreat of the summer sea-ice in the Ross Sea during MIS5e was

  12. Continuous and discrete measurements of atmospheric methane from an ice core from Roosevelt Island, East Ross Sea, Antarctica

    Science.gov (United States)

    Blunier, T.; Simonsen, M. F.; Brook, E.; Lee, J.; Vallelonga, P. T.; Bertler, N. A. N.

    2014-12-01

    A new ice core from Roosevelt Island was drilled for the Roosevelt Island Climate Evolution (RICE) project to establish the history of deglaciation of the Ross Sea. Evidence of glacial retreat in the Ross Sea Embayment shows that deglaciation happened in several stages of rapid collapse and persisted well after the melting of the Northern Hemisphere ice sheets was complete. The drill location on a small island surrounded by sea ice makes dating the core a challenge. We present a timescale for Roosevelt Island using mixing ratios of methane in air preserved within the ice core measured continuously with a Picarro laser spectrometer as well as in high-resolution with gas chromatography (GC). Discrete data from GC analysis over the top 400m of core replicate both the magnitude and variations from other high-resolution ice core records from WAIS Divide, Law Dome, GISP2 and NEEM S1. Both the continuous and discrete methane records of the RICE core were matched to these established records and provide an accurate and consistent depth-age relationship for the past 3.6kyr. The deeper part of the core was measured continuously in July 2014. First inspection of the data suggests that the oldest section of the core reaches into the previous interglacial (Eemian). We will present preliminary evaluated continuous methane data for the deeper part of the core together with a first time scale for the Roosevelt Island ice core.

  13. Predicting responses of the Adélie penguin population of Edmonson Point to future sea ice changes in the Ross Sea

    Directory of Open Access Journals (Sweden)

    Tosca eBallerini

    2015-02-01

    Full Text Available Atmosphere-Ocean General Circulation Models (AOGCMs predict changes in the sea ice environment and in atmospheric precipitations over larger areas of Antarctica. These changes are expected to affect the population dynamics of seabirds and marine mammals, but the extent of this influence is not clear. We investigated the future population trajectories of the colony of Adélie penguins at Edmonson Point, in the Ross Sea, from 2010 to 2100. To do so, we incorporated the relationship between sea ice and demographic parameters of the studied colony into a matrix population model. Specifically, we used sea ice projections from AOGCMs and a proxy for snowfall precipitation. Simulations of population persistence under future climate change scenarios showed that a reduction in sea ice extent and an increase in precipitation events during the breeding season will drive the population to extinction. However, the population growth rate estimated by the model was lower than the population growth rate observed during the last decades, suggesting that recruits from other colonies maintain the observed population dynamics at Edmonson Point. This local ‘rescue’ effect is consistent with a metapopulation dynamic for Adélie penguins in the Ross Sea, in which neighboring colonies might exhibit contrasting population trends and different density-dependent effects. In the hypothesis that connectivity with larger source colonies or that local recruitment would decrease, the sink colony at Edmonson Point is predicted to disappear.

  14. One new genus and three new species of deep-sea nematodes (Nematoda: Microlaimidae) from the Southwest Pacific Ocean and Ross Sea.

    Science.gov (United States)

    Leduc, Daniel

    2016-02-11

    New deep-sea nematodes of the family Microlaimidae are described from the Southwest Pacific Ocean and Ross Sea. Microlaimus korari n. sp. is characterised by annulated cuticle with longitudinal bars, round amphideal aperture slightly smaller than the cryptospiral amphideal fovea, spacious and heavily cuticularised buccal cavity with large dorsal tooth and right subventral tooth situated anteriorly relative to left subventral tooth, slender spicules 4.4 cloacal body diameters long, and gubernaculum 1.2 cloacal body diameters long with laterally curved distal end and swollen proximal end. Bolbolaimus tongaensis n. sp. is characterised by annulated cuticle with longitudinal bars, oval amphideal aperture and cryptocircular amphideal fovea situated between cephalic setae and only partially surrounded by cuticle annulations, and short spicules cuticularised along dorsal edge and at proximal end and with swollen portion near proximal end. Maragnopsia n. gen. is characterised by a minute, non-cuticularised mouth cavity without teeth, an elongated posterior pharyngeal bulb more than twice as long as it is wide, a single outstretched testis, and a conico-cylindrical tail 13-16 anal body diameters long. A list of all 83 valid Microlaimus species is provided. The present study provides the first microlaimid species records from deep-sea habitats (> 200 m depth) in the Southwest Pacific and Ross Sea. The presence of M. korari n. sp. on both the continental slope of New Zealand and Ross Sea abyssal plain suggests that this species has a wide geographical and depth distribution. However, molecular analyses will be required to confirm the identity of these two geographically disparate populations.

  15. Paleomagnetism of sedimentary cores from the Ross Sea outer shelf and continental slope (PNRA-ROSSLOPE II Project)

    Science.gov (United States)

    Macrì, Patrizia; Sagnotti, Leonardo; Caricchi, Chiara; Colizza, Ester

    2016-04-01

    We carried out a paleomagnetic and rock magnetic study of 4 gravity cores sampled in the Ross Sea continental slope of the area to the east of Pennell-Iselin banks. The cores (RS14-C1, C2, C3 and ANTA99-C20) consist of hemipelagic fine-grained (silty-clays) sediments with an IRD component. Rock magnetic and paleomagnetic measurements were carried out at 1-cm spacing on u-channel samples. The data indicate that the cored sediments carry a well-defined characteristic remanent magnetization (ChRM) and have a valuable potential to reconstruct dynamics and amplitude of the geomagnetic field variation at high southern latitudes (ca. 75°S) during the Holocene and the late Pleistocene. The paleomagnetic and rock magnetic data are integrated in a multidisciplinary context which includes previous geological, geophysical, oceanographic and morpho-bathimetric data obtained in the same area in the frame of the PNRA/ROSSLOPE (Past and present sedimentary dynamic in the ROSS Sea: a multidisciplinary approach to study the continental slope) Project. The main aim of the project is to investigate the relation between present and past water mass circulation and to provide a basis for paleoceanographic reconstructions and for the development of a depositional model of the modern processes active along the continental slope.

  16. Lithology and chronology of ice-sheet fluctuations (magnetic susceptibility of cores from the western Ross Sea)

    Science.gov (United States)

    Jennings, Anne E.

    1993-01-01

    The goals of the marine geology part of WAIS include reconstructing the chronology and areal extent of ice-sheet fluctuations and understanding the climatic and oceanographic influences on ice-sheet history. As an initial step toward attaining these goals, down-core volume magnetic susceptibility (MS) logs of piston cores from three N-S transects in the western Ross Sea are compared. The core transects are within separate petrographic provinces based on analyses of till composition. The provinces are thought to reflect the previous locations of ice streams on the shelf during the last glaciation. Magnetic susceptibility is a function of magnetic mineral composition, sediment texture, and sediment density. It is applied in the western Ross Sea for two purposes: (1) to determine whether MS data differentiates the three transects (i.e., flow lines), and thus can be used to make paleodrainage reconstructions of the late Wisconsinan ice sheet; and (2) to determine whether the MS data can aid in distinguishing basal till diamictons from diamictons of glacial-marine origin and thus, aid paleoenvironmental interpretations. A comparison of the combined data of cores in each transect is presented.

  17. MEASURING SEA ICE DRIFT VIA CROSS-CORRELATION OF RADAR ICE IMAGES

    Institute of Scientific and Technical Information of China (English)

    SUN He-quan; SHEN Yong-ming; Qiu Da-hong

    2004-01-01

    The motion of sea ice has a great effect on winter navigation, and oil field exploration in the Bohai Sea. It is very important to measure the ice drift accurately and efficiently. As a practical technique, radar imagery has been used for sea ice monitoring and forecasting for a long time. Combining with the radar imagery and cross-correlation technique, a new measurement method based on the cross-correlation of radar ice images is specified in this paper to obtain full field measurement of sea ice drift. The theory and fast implementation of cross-correlation are presented briefly in the paper, including the filtering method to modify the invalid vectors. To show deeply the validity of the present method, the velocity maps of sea ice drift are provided in the paper, which are calculated from the radar images grabbed in the Liaodong Gulf. The comparison with the traditional tracing method is also conducted.

  18. Pockmarks, Western Ross Sea, Antarctica and Mendeleev Ridge, Central Arctic Ocean: Recent and/or Prevalent?

    Science.gov (United States)

    Lawver, L. A.; Hornbach, M. J.; Davis, M. B.; Brumley, K.; Phillips, R. L.

    2008-12-01

    In 2004, the NBP-0401 cruise to the western Ross Sea, found a large field of pockmarks to the north and west of Franklin Island. The pockmarks ranged in size up to 300 m or more in diameter and are up to 30 m deep. The pockmarks are generally circular and are found in a partially surveyed 3,000 km2 region at water depths ranging from 450 m to 510 m. The pockmarks were most concentrated in an area of approximately 400 km2 where they cover as much as 20% of the seafloor. About 50 km to the west of the heavily pockmarked area, a series of seafloor constructions, up to 5 km in diameter and 120 m high were found in water depths of 490 m to 520 m. Again, ice conditions precluded a complete survey but it is believed the circular features may be carbonate mounds very similar in size and water depth to the ones found by Shannon et al. (2007) in the Porcupine Bight region, offshore Ireland. In 2006, the HLY-0602 cruise undertook a seismic refraction experiment along the Mendeleev Ridge in the Arctic ocean. In the course of the experiment, two to three multibeam lines were run approximately along the crest of the ridge from 76° 40'N to 78° 50'N. On HLY-0503, pockmarks were found in the vicinity of 78° 15'N including one extraordinary cluster of pockmarks at 78° 20'N which were cored on HLY-0602. Three gravity cores taken within pockmarks recovered a significant shell hash in the upper 1 cm but carbon analysis on the shells did not reveal any evidence of chemosynthetic origin for the mollusks. Cores taken along the ridge but away from pockmarks had at most a single shell in the upper 1 cm. Shells were not found below the surface of the cores. Pockmarks along the Mendeleev Ridge are found at depths from 820 m to an extraordinary feature at a depth of ~1420 M. This collapse? feature is 10 km by 5 km with a series of pockmarks in its deepest part. The major feature itself has a central depth of 1480 m but pockmarks withing the feature are as deep as 1520 m at their individual

  19. Trends in the breeding population of Adélie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

    Science.gov (United States)

    Lyver, Phil O'B; Barron, Mandy; Barton, Kerry J; Ainley, David G; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R

    2014-01-01

    Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then.

  20. Trends in the breeding population of Adelie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

    Directory of Open Access Journals (Sweden)

    Phil O'B Lyver

    Full Text Available Measurements of the size of Adélie penguin (Pygoscelis adeliae colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28% of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island. The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni, may explain the sharp increasing trend evident since then.

  1. Diatom-based correlation of early to mid-Pliocene drillcores from the southwestern Ross Sea, Antarctica

    Science.gov (United States)

    Winter, Diane; Sjunneskog, Charlotte; Scherer, Reed; Maffioli, Paola; Harwood, David

    2012-10-01

    The ANDRILL AND-1B drillcore in southern Victoria Land Basin, Antarctica recovered an upper Miocene to early Pleistocene continental shelf stratigraphic section, including a spectacular Pliocene and Pleistocene sequence of alternating diamictite and diatom-rich sediments. This punctuated sequence reflects variation between glacial sediments deposited by ice advance over the site and open-marine diatom productivity and sedimentation. An early Pliocene age for the base of diatom-rich sediment is constrained through integrated diatom biostratigraphy and magnetostratigraphy. The presence of marine diatom Shionodiscus tetraoestrupii from the top of the core to 583.64 mbsf indicates the lowest diatom-bearing sediments are younger than 5 Ma. This drillcore provides important new chronostratigraphic control for paleoenvironmental changes also recorded in three drillcores from the western coast of the McMurdo Sound area, DVDP-10 and -11 in Taylor Valley and CIROS-2 from the seaward edge of Ferrar Fjord. The refined continental shelf biostratigraphy developed from AND-1B provides a framework for regional correlation to understand better the timing and character of large paleoenvironmental changes in the western Ross Sea that involve the history of the West Antarctic Ice Sheet (WAIS). Multivariate analysis, along with traditional biostratigraphic approaches, enables the correlation and comparison of coeval intervals in these drillcores. A composite stratigraphic sequence from these four cores suggests the early and mid-Pliocene Ross Sea experienced extended intervals of open-marine conditions with minimal sea-ice cover and high diatom production and sedimentation. This new information provides important constraints on Antarctic paleoclimate and ice sheet history during an important interval when global climate was warmer than today. The history preserved in these four drillcores will be an important tool to guide and test future ice sheet and climate models.

  2. Dissolved iron transport pathways in the Ross Sea: Influence of tides and horizontal resolution in a regional ocean model

    Science.gov (United States)

    Mack, Stefanie L.; Dinniman, Michael S.; McGillicuddy, Dennis J.; Sedwick, Peter N.; Klinck, John M.

    2017-02-01

    Phytoplankton production in the Ross Sea is regulated by the availability of dissolved iron (dFe), a limiting micro-nutrient, whose sources include Circumpolar Deep Water, sea ice melt, glacial melt, and benthic sources (sediment efflux and remineralization). We employ a passive tracer dye to model the benthic dFe sources and track pathways from deep areas of the continental shelf to the surface mixed layer in simulations with and without tidal forcing, and at 5 and 1.5 km horizontal resolution. This, combined with dyes for each of the other dFe sources, provides an estimate of total dFe supply to surface waters. We find that tidal forcing increases the amount of benthic dye that covers the banks on the continental shelf. Calculations of mixed layer depth to define the surface ocean give similar average values over the shelf, but spatial patterns differ between simulations, particularly along the ice shelf front. Benthic dFe supply in simulations shows an increase with tidal forcing and a decrease with higher resolution. The changes in benthic dFe supply control the difference in total supply between simulations. Overall, the total dFe supply from simulations varies from 5.60 to 7.95 μmol m-2 year-1, with benthic supply comprising 32-50%, comparing well with recent data and model synthesis. We suggest that including tides and using high horizontal resolution is important, especially when considering spatial variability of iron supply on the Ross Sea shelf.

  3. The Pianosa Contourite Depositional System (Northern Tyrrhenian Sea): drift morphology and Plio-Quaternary stratigraphic evolution

    Science.gov (United States)

    Miramontes Garcia, Elda; Cattaneo, Antonio; Jouet, Gwenael; Thereau, Estelle; Thomas, Yannick; Rovere, Marzia; Cauquil, Eric; Trincardi, Fabio

    2016-04-01

    The Pianosa Contourite Depositional System (CDS) is located in the Corsica Trough (Northern Tyrrhenian Sea), a confined basin dominated by mass transport and contour currents in the eastern flank and by turbidity currents in the western flank. The morphologic and stratigraphic characterisation of the Pianosa CDS is based on multibeam bathymetry, seismic reflection data (multi-channel high resolution mini GI gun, single-channel sparker and CHIRP), sediment cores and ADCP data. The Pianosa CDS is located at shallow to intermediate water depths (170 to 850 m water depth) and is formed under the influence of the Levantine Intermediate Water (LIW). It is 120 km long, has a maximum width of 10 km and is composed of different types of muddy sediment drifts: plastered drift, separated mounded drift, sigmoid drift and multicrested drift. The reduced tectonic activity in the Corsica Trough since the early Pliocene permits to recover a sedimentary record of the contourite depositional system that is only influenced by climate fluctuations. Contourites started to develop in the Middle-Late Pliocene, but their growth was enhanced since the Middle Pleistocene Transition (0.7-0.9 Ma). Although the general circulation of the LIW, flowing northwards in the Corsica Trough, remained active all along the history of the system, contourite drift formation changed, controlled by sediment influx and bottom current velocity. During periods of sea level fall, fast bottom currents often eroded the drift crest in the middle and upper slope. At that time the proximity of the coast to the shelf edge favoured the formation of bioclastic sand deposits winnowed by bottom currents. Higher sediment accumulation of mud in the drifts occurred during periods of fast bottom currents and high sediment availability (i.e. high activity of turbidity currents), coincident with periods of sea level low-stands. Condensed sections were formed during sea level high-stands, when bottom currents were more sluggish

  4. The influence of short-term events on the hydrographic and biological structure of the southwestern Ross Sea

    Science.gov (United States)

    Jones, Randolph M.; Smith, Walker O.

    2017-02-01

    The Ross Sea continental shelf supports very high productivity and phytoplankton biomass. Conventional methods, including ship-based sampling, instrumented moorings, satellite imagery, and modelling, have illustrated the typical patterns of seasonal progression of the phytoplankton blooms. While variability in the Ross Sea is substantial over relatively large scales, our understanding of smaller scales of variability (on the order of a few hours or several kilometers) is limited. Utilizing data from an autonomous glider, we examined the mechanisms driving both the transitions between stages of the phytoplankton bloom and the short-term perturbations in chlorophyll concentrations. Three phases within the bloom were defined based on chlorophyll changes: an accumulation phase, a dissipation period, and a post-dissipation phase. Short-term perturbations in chlorophyll were repeatedly observed and correlated with wind speed. These chlorophyll perturbations were strongly influenced by the degree of temporal coupling between wind events and the depth of mixing, which varied among phases. Delays of 12-24 h between wind events and chlorophyll changes were observed during the accumulation phase, but shortened to 2-12 h in the dissipation phase. Furthermore, while physical factors contributed to the observed short-term reductions in biomass and the appearance of chlorophyll at depth throughout the study, we hypothesize that turbulence during the period of maximum biomass induced aggregate formation and led to rapid vertical flux. These results suggest that the small-scale, short-term physical perturbations may induce substantial vertical redistribution of biogenic material, which in turn can have significant biogeochemical impacts.

  5. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

    Science.gov (United States)

    Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-07-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

  6. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II:Electromagnetic backscattering model

    Institute of Scientific and Technical Information of China (English)

    谢涛; William Perrie; 赵尚卓; 方贺; 于文金; 何宜军

    2016-01-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface.

  7. Spatial analysis of trends in primary production and relationship with large-scale climate variability in the Ross Sea, Antarctica (1997-2013)

    Science.gov (United States)

    Schine, Casey M. S.; van Dijken, Gert; Arrigo, Kevin R.

    2016-01-01

    Recent studies have documented an increase in sea ice extent and the duration of the ice season in the Ross Sea, Antarctica. We conducted a satellite-based study to quantify changes in net primary production (NPP) and chlorophyll a (Chl a) in response to the observed changes in ice dynamics in the Ross Sea south of 60°S. Our study covers a 16 year time period (1997-2013) and incorporates both the shelf and off-shelf regions of the Ross Sea. We observed significant secular changes in NPP from 1997 to 2013 in the off-shelf region, with NPP increasing on the eastern side and decreasing on the western side of our study area. The changes we observed in NPP are consistent with the changes we observed in sea surface temperature (SST) and open water days (OWDs), decreasing (increasing) on the western (eastern) side of our study area. Finally, we examined the influence of the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO), on SST, OWDs, Chl a, and NPP in the Ross Sea and observed a significant relationship between the state of the SAM and ENSO and SST, OWDs, and NPP across the study region. The response of OWDs, SST, and NPP to atmospheric forcing by SAM and ENSO was opposite for the shelf and off-shelf regions, such that during a positive phase of SAM or negative phase of ENSO (La Niña), SST, OWDs, and NPP increased on the shelf and decreased in the off-shelf region.

  8. Drift in salinity data from Argo profiling floats in the Sea of Japan

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Bajish, C.C.; Behera, S.; Gopalakrishna, V.V.

    . The efficiency of this new method in finding out possible drift in the Argo salinity is demonstrated in the Sea of Japan (SOJ) by using the "near-linear" subsurface salinity structure of the SOJ. The new method is based on the time–space decorrelation scale...

  9. On the Detection of Drifting Sea Mines using Above- and Underwater Sensors

    NARCIS (Netherlands)

    Dol, H.S.; Sabel, J.C.; Lensen, H.A.; Beckers, A.L.D.

    2010-01-01

    Small drifting objects can be a big threat to surface ships, especially when the objects are explosion hazards like sea mines that have become detached from their moorings. Timely detection of such objects is crucial in order to be able to perform adequate evasive manoeuvres. However, the vertical p

  10. Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

    Science.gov (United States)

    Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

    2011-01-01

    We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

  11. An analytical model for wind-driven Arctic summer sea ice drift

    Directory of Open Access Journals (Sweden)

    H.-S. Park

    2015-03-01

    Full Text Available The authors present an approximate analytical model for wind-induced sea-ice drift that includes an ice–ocean boundary layer with an Ekman spiral in the ocean velocity. This model provides an analytically tractable solution that is most applicable to the marginal ice zone, where sea-ice concentration is substantially below 100%. The model closely reproduces the ice and upper-ocean velocities observed recently by the first ice-tethered profiler equipped with a velocity sensor (ITPV. The analytical tractability of our model allows efficient calculation of the sea-ice velocity provided that the surface wind field is known and that the ocean surface geostrophic velocity is relatively weak. The model is applied to estimate intraseasonal variations in Arctic sea ice cover due to short-timescale (around 1 week intensification of the southerly winds. Utilizing 10 m surface winds from ERA-Interim reanalysis, the wind-induced sea-ice velocity and the associated changes in sea-ice concentration are calculated and compared with satellite observations. The analytical model captures the observed reduction of Arctic sea-ice concentration associated with the strengthening of southerlies on intraseasonal time scales. Further analysis indicates that the wind-induced surface Ekman flow in the ocean increases the sea-ice drift speed by 50% in the Arctic summer. It is proposed that the southerly wind-induced sea-ice drift, enhanced by the ocean's surface Ekman transport, can lead to substantial reduction in sea-ice concentration over a timescale of one week.

  12. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE and NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 10 November 1997 to 12 December 1997 (NODC Accession 0000898)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  13. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE in the Ross Sea and Southern Oceans from 13 November 1996 to 26 November 1996 (NODC Accession 0000895)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE. Data were collected from 13...

  14. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE in the Ross Sea and Southern Oceans from 06 September 1996 to 12 September 1996 (NODC Accession 0000890)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from POLAR DUKE. Data were collected from 06 September...

  15. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE in the Ross Sea and Southern Oceans from 05 February 1992 to 28 February 1992 (NODC Accession 0000888)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE. Data were collected from 05...

  16. Temperature profile and nutrients data collected using bottle casts from the NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 16 December 1995 to 13 January 1996 (NODC Accession 0000889)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the NATHANIEL B. PALMER. Data were collected from...

  17. Temperature profile and nutrients data collected using bottle casts from the NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 09 November 1994 to 08 December 1994 (NODC Accession 0000899)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the NATHANIEL B. PALMER. Data were collected from...

  18. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE and NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 08 April 1997 to 05 May 1997 (NODC Accession 0000897)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  19. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE AND NATHANIEL B. PALMER in the Ross Sea and Southern Oceans from 12 January 1997 to 09 February 1997 (NODC Accession 0000896)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from the POLAR DUKE and NATHANIEL B. PALMER. Data were...

  20. Temperature profile and nutrients data collected using bottle casts from the POLAR DUKE in the Ross Sea and Southern Oceans from 08 October 1996 to 06 November 1996 (NODC Accession 0000894)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts in the Ross Sea and Southern Oceans from POLAR DUKE. Data were collected from 08 October...

  1. Drift data of the sea-gravity meter (SL-2) installed on the R/V Hakurei-maru; `Hakureimaru` senjo jurokei (SL-2) no drift ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Joshima, M. [Geological Survey of Japan, Tsukuba (Japan); Ishihara, T. [Japan National Oil Corp., Tokyo (Japan)

    1996-05-01

    This paper reports a rapid change in the drift of a sea-gravity meter SL-2 after 1987 and after its modification in 1993. In order to confirm the accuracy of the sea-gravity meter of the Hakurei-maru, changes in the lapse of time were summarized on the relative gravity value at the Funabashi base and on the drift rate in each voyage. The drift rates in the case of departing from and returning to Funabashi base were all less than 0.1mgal/day except the first year of 1987, which was presumably due to the growing stability of the gravimeter. The drift value of 1992 was 0.05mgal/day, producing an error of only 2mgal without drift compensation at the end of a 40 day voyage. The gravimeter after the total renewal of the control part in 1993 produced a large drift in the direction opposite to the conventional drift. The cause of these phenomena was supposed to be some kind of change in the spring property during the gap of one year; this large drift seemed to be settling down after the elapse of approximately one year. 4 refs., 8 figs., 2 tabs.

  2. Insect drift over the northern Arabian Sea in early summer

    Digital Repository Service at National Institute of Oceanography (India)

    Pathak, S.C.; Kulshrestha, V.; Choubey, A.K.; Parulekar, A.H.

    Air borne insects, mostly carried by wind currents, were trapped over the northern Arabian Sea (16 degrees to 20 degrees N; 68 degrees to 72 degrees E), in the course of cruise No. 111, ORV Sagar Kanya (March 14 to April 7, 1996). A total of 2...

  3. Multidisciplinary study of sediments deposited in the Ross Sea (Antarctica) during the last 50 ka: information on changes of ice extent during the glacial-interglacial transition

    Science.gov (United States)

    Del Carlo, Paola; Baneschi, Ilaria; Bertagnini, Antonella; Boschi, Chiara; Cascella, Antonio; Colizza, Ester; Di Roberto, Alessio; Di Vincenzo, Gianfranco; Finocchiaro, Furio; Landi, Patrizia; Lirer, Fabrizio; Pompilio, Massimo; Sagnotti, Leonardo; Sangiorgi, Francesca; Sprovieri, Mario; Wrinkler, Aldo

    2013-04-01

    In the Ross Sea (Antarctica), sedimentation is controlled by the dynamics of the ice shelves, fluctuations of the ice sheets extensions (Eastern and Western) and volcanic activity from several volcanic complex of the Victoria Land. Marine sediments consisting of alternated glacigenic, biogenic and volcanic deposits can be interpreted in terms of changes in paleoclimate and paleoenvironment conditions. In this project we present a multidisciplinary study (comprising tephrostratigraphy, petrology, paleomagnetism, rock magnetism, TIC/TOC geochemistry, Ar/Ar dating, palinology and integrated biostratigraphy of forams and calcareous nannoplankton) of the sediments recovered in selected cores from Ross Sea during 1999 and 2000 cruises and stored in the Italian archive at Museo Nazionale dell'Antartide (Trieste). Results provide new data on local and/or global changes of paleoclimate and paleoenvironmental conditions over the past 50 Ka. Furthermore, the study of the recovered volcanic deposits adds new information about the poorly known, recent volcanic activity in the Victoria Land area.

  4. A seasonal study of dissolved cobalt in the Ross Sea, Antarctica: micronutrient behavior, absence of scavenging, and relationships with Zn, Cd, and P

    Directory of Open Access Journals (Sweden)

    M. A. Saito

    2010-08-01

    Full Text Available We report the distribution of cobalt (Co in the Ross Sea polynya during austral summer 2005–2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo was similar to soluble reactive phosphate (PO43-, with dCo and PO43- showing a significant correlation throughout the water column (r2=0.87. A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from ~45–85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range of this seasonal variability (~30 pM dCo, with concentrations as low as 20 pM observed in some regions where PO43- was depleted to ~0.1 μM. Both complexed Co, defined as the fraction of dCo bound by strong organic ligands, and labile Co, defined as the fraction of dCo not bound by these ligands, were typically observed in significant concentrations throughout the water column. This contrasts the depletion of labile Co observed in the euphotic zone of other ocean regions, suggesting a much higher bioavailability for Co in the Ross Sea. An ecological stoichiometry of 37.6 μmol Co:mol−1 PO43- calculated from dissolved concentrations was similar to values observed in the subarctic Pacific, but approximately tenfold lower than values in the Eastern Tropical Pacific and Equatorial Atlantic. The ecological stoichiometries for dissolved Co and Zn suggest a greater overall use of Zn relative to Co in the shallow waters of the Ross Sea, with a Co:PO43-/Zn:PO43- ratio of 1:17. Comparison of these observed stoichiometries with values estimated in culture studies suggests that Zn is a key micronutrient that likely influences phytoplankton diversity in the Ross Sea. In contrast, the

  5. Influence of Ross Sea Bottom Water changes on the warming and freshening of the Antarctic Bottom Water in the Australian-Antarctic Basin

    Directory of Open Access Journals (Sweden)

    K. Shimada

    2012-07-01

    Full Text Available Changes to the properties of Antarctic Bottom Water in the Australian-Antarctic Basin (AA-AABW between the 1990s and 2000s are documented using data from the WOCE Hydrographic Program (WHP and repeated hydrographic surveys. Strong cooling and freshening are observed on isopycnal layers denser than γn = 28.30 kg m−3. Changes in the average salinity and potential temperature below this isopycnal correspond to a basin-wide warming of 1300 ± 200 GW and freshening of 24 ± 3 Gt year−1. Recent changes to dense shelf water in the source regions in the Ross Sea and George V Land can explain the freshening of AA-AABW but not its extensive warming. An alternative mechanism for this warming is a decrease in the supply of AABW from the Ross Sea (RSBW. Hydrographic profiles between the western Ross Sea and George V Land (171–158° E were analyzed with a simple advective-diffusive model to assess the causes of the observed changes. The model suggests that the warming of RSBW observed between the 1970s and 2000s can be explained by a 21 ± 23% reduction in RSBW transport and the enhancement of the vertical diffusion of heat resulting from a 30 ± 7% weakening of the abyssal stratification. The documented freshening of Ross Sea dense shelf water leads to a reduction in both salinity and density stratification. Therefore the direct freshening of RSBW at its source also produces an indirect warming of the RSBW. A simple box model suggests that the changes in RSBW properties and volume transport (a decrease of 6.7% is assumed between the year 1995 and 2005 can explain 51 ± 6% of the warming and 84 ± 10% of the freshening observed in AA-AABW.

  6. Wind-induced drift of objects at sea: the leeway field method

    CERN Document Server

    Breivik, Øyvind; Maisondieu, Christophe; Roth, Jens Christian; 10.1016/j.apor.2011.01.005

    2011-01-01

    A method for conducting leeway field experiments to establish the drift properties of small objects (0.1-25 m) is described. The objective is to define a standardized and unambiguous procedure for condensing the drift properties down to a set of coefficients that may be incorporated into existing stochastic trajectory forecast models for drifting objects of concern to search and rescue operations and other activities involving vessels lost at sea such as containers with hazardous material. An operational definition of the slip or wind and wave-induced motion of a drifting object relative to the ambient current is proposed. This definition taken together with a strict adherence to 10 m wind speed allows us to refer unambiguously to the leeway of a drifting object. We recommend that all objects if possible be studied using what we term the direct method, where the object's leeway is studied directly using an attached current meter. We divide drifting objects into four categories, depending on their size. For th...

  7. ON THE LATE OCCURRENCE OF DRIFT ICE RETREAT FROM THE HOKKAIDO COAST IN THE 1992/93 SEA ICE SEASON

    OpenAIRE

    トヨタ, タケノブ; カミヒラ, エツロウ; Takenobu, TOYOTA; Etsuro, KAMIHIRA

    1994-01-01

    The 1992/93 sea ice season in the Sea of Okhotsk was characterized by the record-breaking late appearance and late disappearance of drift ice off the Hokkaido coast. The 1992/93 winter season was rather warm and the arrival of drift ice off the Hokkaido coast was a few weeks later than normal. The averaged amount of drift ice in sight at Kitamiesashi, Omu, Mombetsu, and Abashiri was half of normal. Nevertheless the last dates of drift ice at the four observatories were all in early May, about...

  8. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JAMES CLARK ROSS in the North Greenland Sea and Norwegian Sea from 1996-07-20 to 1996-08-22 (NODC Accession 0113757)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113757 includes chemical, discrete sample, physical and profile data collected from JAMES CLARK ROSS in the North Greenland Sea and Norwegian Sea...

  9. Chemical evidence of the changes of the Antarctic Bottom Water ventilation in the western Ross Sea between 1997 and 2003

    Science.gov (United States)

    Rivaro, Paola; Massolo, Serena; Bergamasco, Andrea; Castagno, Pasquale; Budillon, Giorgio

    2010-05-01

    Data from three Italian CLIMA project cruises between 1997 and 2003 were used to obtain sections of the hydrographic and chemical properties of the main water masses across the shelf break off Cape Adare (western Ross Sea, Antarctica). Dissolved oxygen, nitrate and phosphate data were combined on the basis of the Redfield ratio to obtain the quasi-conservative tracers NO (9[NO 3]+[O 2]), PO (135[PO 4]+[O 2]) and phosphate star PO4* ( PO4*=[PO 4]+[O 2]/175-1.95). In 1997 and 2003 the presence of the High Salinity Shelf Water at the bottom depth near the sill was traced by both physical and chemical measurements. In 2001 the Modified Shelf Water, characterized by warmer temperature and by a lower dissolved oxygen content than High Salinity Shelf Water, was observed at the shelf edge. The distribution of the chemical tracers together with the hydrographic observations showed recently formed Antarctic Bottom Water on the continental slope during all of the cruises. These observations were confirmed by the extended optimum multiparameter analysis. The calculated thickness of the new Antarctic Bottom Water, as well as the tracer content, were variable in time and in space. The estimated volume of the new Antarctic Bottom Water and the export of dissolved oxygen and nutrient associated with the overflowing water were different over the examined period. In particular, a lower (˜55%) export was evidenced in 2001 compared to 1997.

  10. Mesoscale variability of the summer bloom over the northern Ross Sea shelf: A tale of two banks

    Science.gov (United States)

    Kohut, Josh T.; Kustka, Adam B.; R. Hiscock, Michael; Lam, Phoebe J.; Measures, Chris; Milligan, Allen; White, Angelicque; Carvalho, Filipa; Hatta, Mariko; Jones, Bethan M.; Ohnemus, Daniel C.; Swartz, John M.

    2017-02-01

    Multi-year satellite records indicate an asymmetric spatial pattern in the summer bloom in the Northern Ross Sea, with the largest blooms over the shallows of Pennell Bank compared to Mawson Bank. In 2010-2011, high-resolution spatiotemporal in situ sampling focused on these two banks to better understand factors contributing to this pattern. Dissolved and particulate Fe profiles suggested similar surface water depletion of dissolved Fe on both banks. The surface sediments and velocity observations indicate a more energetic water column over Mawson Bank. Consequently, the surface mixed layer over Pennell Bank was more homogeneous and shallower. Over Mawson Bank we observed a thicker more homogeneous bottom boundary layer resulting from stronger tidal and sub-tidal currents. These stronger currents scour the seafloor resulting in sediments less likely to release additional sedimentary iron. Estimates of the quantum yield of photosynthesis and the initial slope of the photosynthesis-irradiance response were lower over Mawson Bank, indicating higher iron stress over Mawson Bank. Overall, the apparent additional sedimentary source of iron to, and longer surface residence time over Pennell Bank, as well as the reduced fluxes from the more isolated bottom mixed layer over Mawson Bank, sustain the observed asymmetric pattern across both banks.

  11. Spring-time dynamics of diatom communities in landfast and underlying platelet ice in Terra Nova Bay, Ross Sea, Antarctica

    Science.gov (United States)

    Saggiomo, Maria; Poulin, Michel; Mangoni, Olga; Lazzara, Luigi; De Stefano, Mario; Sarno, Diana; Zingone, Adriana

    2017-02-01

    We investigated the composition of diatom communities in annual fast ice and their variations over time during the 1999 austral spring in Terra Nova Bay (Ross Sea, Antarctica). Diatoms varied along the ice core in both cell abundance and species composition, with a minimum in the lower layer and a peak in the platelet ice. Planktonic species constituted in total about 98% of the diatom assemblage in the surface layers of the ice core down to the thickness of 220 cm. In the bottom ice and the underlying platelet-ice layer, the contribution of planktonic diatoms was lower (60% and 65%, respectively) at the beginning of the sampling period, and then decreased further to reach 30% in the bottom ice, where a remarkable biomass increase over time was caused by in situ growth and accumulation of benthic species. By contrast in the platelet-ice layer only small changes were recorded in the composition of the diatom assemblage, which was mainly constituted by the bloom of Fragilariopsis nana. The benthic species are generally not found in the water column, while species in the platelet-ice layer presumably constitute the seed for the initial plankton bloom during the ice-free periods in Terra Nova Bay.

  12. Alf Ross

    DEFF Research Database (Denmark)

    Ryberg, Jesper

    En (overvejende) ny generation af akademikere møder og prøver Ross' tanker om emner som retfærdighed, demokrati, statsforfatningsret, ytringsfrihed, straf, erkendelsesteori, etik, logik, fri vilje og sygdom....

  13. Drifting buoy and other data from drifting platforms in the Bering Sea as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 17 January 1981 to 20 June 1981 (NODC Accession 8200120)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from drifting platforms in the Bering Sea by the Flow Research Company as part of the Outer Continental Shelf Environmental...

  14. Sedimentological evidence for a deforming bed in a late Pleistocene glacial sequence from ANDRILL AND-1B, Ross Sea, Antarctica

    Science.gov (United States)

    Cowan, E. A.; Powell, R. D.

    2009-12-01

    A 1,284.87m-long sediment core (AND-1B) was drilled from beneath the McMurdo Ice Shelf sector of the Ross Ice Shelf as part of the Antarctic geological drilling program, ANDRILL. Snapshots of diamictite depositional processes and paleoenvironmental conditions have been interpreted from a nested set of samples collected at overlapping scales of observation. Data used for detailed sedimentological analyses include cm-scale core logging based on x-radiographs of the archive halves in addition to the original core description, bulk samples, and oriented 45 x 70mm thin sections of diamictites for micromorphology analysis. The 5.8m-thick interval studied contains a complete glacial advance-retreat sequence that is bracketed by glacial surfaces of erosion (GSE) at 41.9 and 47.7mbsf recording glacial advance over the core site. 4.6m of subglacial till is deposited above the lower GSE represented by a sequence of thin muddy conglomerate with diverse pebble lithologies, massive clast-rich muddy diamicite, and stratified diamictite with clast-rich and clast-free beds. The sand size fraction of bulk samples and thin sections from the till are dominated by aggregate grains, termed till pellets following terminology used by sedimentologists in the Ross Sea. The core of the pellet may be a lithic grain or stiff till with additional clay plastered on the outside forming rounded grains from angular ones. Till pellets are rounded, spherical to prolate in form and are associated with turbate structures and aligned grains in till thin sections - evidence of rotational deformation. The area beneath an ice shelf in front of a grounding line is recorded by a thin bed of granular particles that transitions to silty claystone stratified with granules. Granular layers are thought to be from periodic winnowing by strong currents focused near the grounding line. The sub-ice shelf transition from proximal grounding line to distal is recorded by a gradational contact between stratified silty

  15. Physical and biological forcing of mesoscale variability in the carbonate system of the Ross Sea (Antarctica) during summer 2014

    Science.gov (United States)

    Rivaro, Paola; Ianni, Carmela; Langone, Leonardo; Ori, Carlo; Aulicino, Giuseppe; Cotroneo, Yuri; Saggiomo, Maria; Mangoni, Olga

    2017-02-01

    Water samples (0-200 m) were collected in a coastal area of the Ross Sea in January 2014 to evaluate the physical and biological forcing on the carbonate system at the mesoscale (distance between stations of 5-10 km). Remote sensing supported the determination of the sampling strategy and helped positioning each sampling station. Total alkalinity, pH, dissolved oxygen, phytoplankton pigments and composition were investigated in combination with measurements of temperature, salinity and current speed. Total inorganic carbon, sea water CO2 partial pressure and the saturation state (Ω) for calcite and aragonite were calculated from the measured total alkalinity and pH. In addition, continuous measurements of atmospheric CO2 concentration were completed. LADCP measurements revealed the presence of a significant change in current speed and direction that corresponded to a clearly defined front characterized by gradients in both temperature and salinity. Phytoplankton biomass was relatively high at all stations and the highest values of chlorophyll-a were found between 20 to 50 m, with the dominant taxonomic group being haptophyceae. The carbonate system properties in surface waters exhibited mesoscale variability with a horizontal length scale of about 10 km. Sea-ice melt, through the input of low salinity water, results in a dilution of the total alkalinity and inorganic carbon, but our observations suggest that phytoplankton activity was the major forcing of the distribution of the carbonate system variables. Higher CO3-, Ω and pH in the surface layer were found where the highest values of chlorophyll-a were observed. The calculated ΔpCO2 pattern follows both MODIS data and in situ chlorophyll-a measurements, and the estimated CO2 fluxes ranged from -0.5 ± 0.4 to -31.0 ± 6.4 mmol m- 2 d- 1. The large range observed in the fluxes is due to both the spatial variability of sea water pCO2 and to the episodic winds experienced.

  16. Introduction of parameterized sea ice drag coefficients into ice free-drift modeling

    Institute of Scientific and Technical Information of China (English)

    LU Peng; LI Zhijun; HAN Hongwei

    2016-01-01

    Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient (Ca) and oceanic drag coefficient (Cw). Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions. In the present study, the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model, and the wind factorα and the deflection angleθ between sea ice drift and wind velocity as well as the ratio ofCa toCw are studied to investigate their dependence on the impact factors such as local drag coefficients, floe and ridge geometry. The results reveal that in an idealized steady ocean,Ca/Cw increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone, while it remains at a steady level (0.2–0.25) for large floes in the central ice zone. The wind factorα increases rapidly at first and approaches a steady level of 0.018 whenA is greater than 20%. And the deflection angleθ drops rapidly from an initial value of approximate 80° and decreases slowly asA is greater than 20% without a steady level likeα. The values of these parameters agree well with the previously reported observations in Arctic. The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient (Cs’/Cs) and the ratio of ridge form drag coefficient (Cr’/Cr) to the value of Ca/Cw,α, andθ, because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces. Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.

  17. Mesoscale variability in intact and ghost colonies of Phaeocystis antarctica in the Ross Sea: Distribution and abundance

    Science.gov (United States)

    Smith, Walker O.; McGillicuddy, Dennis J.; Olson, Elise B.; Kosnyrev, Valery; Peacock, Emily E.; Sosik, Heidi M.

    2017-02-01

    Phaeocystis, a genus with a cosmopolitan distribution and a polymorphic life cycle, was observed during summer in the Ross Sea, Antarctica, where large blooms of this haptophyte regularly occur. The mesoscale vertical and horizontal distributions of colonies of Phaeocystis antarctica were assessed using a towed Video Plankton Recorder (VPR). The mean size of colonies was 1.20 mm, and mean abundances within the three VPR surveys were 4.86, 1.96, and 11.5 mL- 1. In addition to the typical spherical, transparent colonies, the VPR quantified an optically dissimilar form of colony that had a distinctive translucent appearance. It also measured the abundance of collapsed colonies, similar to those observed previously from cultures and mesocosms, which we called "ghost colonies". The translucent colonial form had a different distribution than the more common colonial form, and at times was more abundant. Relative to intact colonies, the ghost colonies occurred less frequently, with mean abundances in the three surveys being 0.01, 0.08, and 0.0004 mL- 1. Ghost colonies generally were found below the euphotic zone, where they often were in greater abundance than intact colonies. However, the relationship of ghost colonies to intact P. antarctica colonies was not direct or consistent, suggesting that the formation of ghost colonies from living colonies and their appearance within the water column were not tightly coupled. Given their relative scarcity and low carbon content, it is unlikely that ghost colonies contribute substantially to vertical flux; however, it is possible that we did not sample periods of major flux events, and as a result minimized the importance of ghost colonies to vertical flux. They do, however, represent a poorly documented feature of polar haptophyte life cycles.

  18. Holocene laminated biogenic mud in Wood Bay (western Ross Sea, Antarctica): geochemical data and preliminary paleoclimatic interpretation.

    Science.gov (United States)

    Colizza, Ester; Finocchiaro, Furio; Giglio, Federico; Kuhn, Gerhard; Langone, Leonardo; Presti, Massimo

    2010-05-01

    The study of LGM and Holocene marine sediments is an important goal in Antarctic research and needs high-resolution sequences to reconstruct paleoclimatic events in detail. Literature reports a large number of data coming from inner-shelf bays and fjords, especially around Antarctic peninsula, but also from western Ross Sea. In this note we discuss compositional data from a gravity core (BAY05-45c; 74° 09.7' S, 165° 57.7' E; water depth: 1058 m; core length: 445.5 cm) collected in 2005 during the Italian PNRA cruise into the inner part of Wood Bay, in front of the Aviator Ice tongue. Wood Bay sea floor morphology is charcterised by a narrow basin, deeper than 1,000 m, oriented WNW-ESE, and transversally connected, by a 800-m deep sill, to the Drygalski basin, streching NE-SW. Core sediment is composed by laminated biosiliecous mud, with a strong hydrogen sulphide odour and black in colour. Within a few days from core sampling, sediment became oxidized: laminae colour ranges from dark (from dark olive grey to black) to light (from olive grey to olive). Some lighter laminae have cotton-like texture. Data set include X-ray images, magnetic susceptibility, AMS 14C dating, organic carbon, biogenic silica, XRF-scan of major and minor elements. Discussion of the data will point out inferences about sedimentary processes, paleoproductivity and oceanographic conditions during the Holocene. The most apparent feature is the occurrence, down-core, of at least two intervals of increased productivity, characterised by higher organic carbon and biogenic silica. Within such intervals, a few cm-thick levels show peaks of biogenic silica, as well as of barium, which correspond to relatively lows in organic carbon contents. Organic carbon content is higher in darker laminae, whereas lighter and fluffy laminae display an increased percentage of biogenic silica. Such levels probably mark a rapid and not persistent change in phytoplankton assemblage compositions.

  19. Mapping of sea ice and measurement of its drift using aircraft synthetic aperture radar images

    Science.gov (United States)

    Leberl, F.; Bryan, M. L.; Elachi, C.; Farr, T.; Campbell, W.

    1979-01-01

    Side-looking radar images of Arctic sea ice were obtained as part of the Arctic Ice Dynamics Joint Experiment. Repetitive coverages of a test site in the Arctic were used to measure sea ice drift, employing single images and blocks of overlapping radar image strips; the images were used in conjunction with data from the aircraft inertial navigation and altimeter. Also, independently measured, accurate positions of a number of ground control points were available. Initial tests of the method were carried out with repeated coverages of a land area on the Alaska coast (Prudhoe). Absolute accuracies achieved were essentially limited by the accuracy of the inertial navigation data. Errors of drift measurements were found to be about + or - 2.5 km. Relative accuracy is higher; its limits are set by the radar image geometry and the definition of identical features in sequential images. The drift of adjacent ice features with respect to one another could be determined with errors of less than + or - 0.2 km.

  20. Corticosterone in relation to body mass in Adelie penguins (Pygoscelis adeliae) affected by unusual sea ice conditions at Ross Island, Antarctica.

    Science.gov (United States)

    Cockrem, J F; Potter, M A; Candy, E J

    2006-12-01

    Penguins naturally fast each year during breeding and again whilst moulting, and may lose more than 40% of body mass during a fast. Fasting in emperor (Aptenodytes forsteri) and king (Aptenodytes patagonicus) penguins has been divided into three phases, with phase III characterised by an increased rate of body mass loss, increased plasma corticosterone concentrations, and a change in behaviour leading to abandonment of the breeding attempt and return to sea to feed. Initial corticosterone concentrations and corticosterone responses to a handling stressor were measured in the current study to determine if they increase during phase III of fasting in Adelie penguins (Pygoscelis adeliae). The study was conducted in 2001 at the northern Cape Bird colony on Ross Island, Antarctica. Penguin breeding on Ross Island was disrupted in the 2001-2002 summer by a large iceberg (B15A) which stopped the normal movement of sea ice in the Ross Sea. Penguins departing from the Cape Bird colony were lighter than returning or incubating birds (3.39+/-0.10cf. 4.16+/-0.06 and 4.07+/-0.08kg). It is likely that the departing birds were males that had been lighter than normal when they arrived at the colony. Initial plasma corticosterone concentrations were higher in departing than returning or incubating penguins (6.89+/-1.69cf. 2.36+/-0.42 and 1.08+/-0.19ng/ml). Corticosterone responses to handling were also greater in departing penguins. Initial plasma corticosterone, concentrations at 30min and total and corrected integrated corticosterone responses were inversely related to body mass in departing penguins, whereas there were no relationships in arriving penguins. beta-hydroxybutyrate and uric acid concentrations were consistent with departing birds having entered phase III of fasting. The results indicate that corticosterone and corticosterone responses are elevated in phase III of fasting in the Adelie penguin.

  1. Were West Antarctic Ice Sheet grounding events in the Ross Sea a consequence of East Antarctic Ice Sheet expansion during the middle Miocene?

    Science.gov (United States)

    Bart, Philip J.

    2003-11-01

    Seismic correlation of glacial unconformities from the Ross Sea outer continental shelf to chronostratigraphic control at DSDP sites 272 and 273 indicates that at least two West Antarctic Ice Sheet (WAIS) expansions occurred during the early part of the middle Miocene (i.e. well before completion of continental-scale expansion of the East Antarctic Ice Sheet (EAIS) inferred from δ 18O and eustatic shifts). Therefore, if the volume of the EAIS was indeed relatively low, and if the Ross Sea age model is valid, then these WAIS expansions/contractions were not a direct consequence of EAIS expansion over the Transantarctic Mountains onto West Antarctica. An in-situ development of the WAIS during the middle Miocene suggests that either West Antarctic land elevations were above sea level and/or that air and water temperatures were sufficiently cold to support a marine-based ice sheet. Additional chronostratigraphic and lithologic data are needed from Antarctic margins to test these speculations.

  2. Early Miocene basement clasts in ANDRILL AND-2A core and their implications for paleoenvironmental changes in the McMurdo Sound region (western Ross Sea, Antarctica)

    Science.gov (United States)

    Talarico, Franco M.; Sandroni, Sonia

    2011-07-01

    A detailed provenance study of gravel-size clasts in the lowermost 438 m of the ANDRILL AND-2A core reveals a pattern of dynamic provenance variations which can be discussed for its implications for Early Miocene paleogeographical reconstructions and glaciological models in the McMurdo Sound region (Ross Sea). Clast distribution patterns and distribution of diagnostic basement clast assemblages indicative of three different provenance areas (Mulock-Skelton glacier, Carlyon-Darwin glacier and Koettlitz-Blue glacier regions) can be interpreted in terms of two distinctive ice dynamic scenarios: i) local fluctuations of outlet Transantarctic Mountains glaciers with dominant flows from W to E to the coast (documented in the lowermost core section, at ca. 20.2-20.1 Ma), and ii) larger volume of ice grounded at the regional scale in the Ross Embayment with flow lines running N-S close to the TAM front (in two periods, at ca. 19.7-19.7 Ma and at ca. 17.8-17.4 Ma). Moreover, in core sections including facies typical of open-marine to iceberg-influenced depositional environments, ice-rafted debris compositions reveal that during periods of glacial-minima setting sites of active calving processes dominantly occurred in areas including the present-day Blue-Koettlitz glacier coast, and subordinately in glacier tongues located further south in the Skelton-Mulock glacier area. Consistently with results of numerical modelling the reconstructed glaciological scenarios provide further constraints to paleogeographical reconstructions and glaciological models at the south-western tip of the Ross Sea during significant steps in Antarctic ice sheet evolution through the Early Miocene climatic events.

  3. Scaling aspects of the sea-ice-drift dynamics and pack fracture

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2007-05-01

    Full Text Available A study of the sea-ice dynamics in the periods of time prior to and during the cycles of basin-wide fragmentation of the ice cover in the Arctic Ocean is presented. The fractal geometry of the ice-sheets limited by leads and ridges was assessed using the satellite images, while the data on the correlated sea-ice motion were obtained in the research stations "North Pole 32" and "North Pole 33" established on the ice pack. The revealed decrease of the fractal dimension as a result of large-scale fragmentation is consistent with the localization of the fracture process (leads propagation. At the same time, the scaling properties of the distribution of amplitudes of ice-fields accelerations were insensitive to the event of sea-ice fragmentation. The temporal distribution of the accelerations was scale-invariant during "quiet" periods of sea-ice drift but disordered in the period of mechanical perturbation. The period of decorrelated (in time ice-field motion during the important fracture event was interpreted as an inter-level transition in the hierarchic dynamical system. The mechanism of the long-range correlations in the sea-ice cover, including the fracture process, is suggested to be in relation with the self-organized oscillation dynamics inherent in the ice pack.

  4. Scaling aspects of the sea-ice-drift dynamics and pack fracture

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2007-01-01

    Full Text Available A study of the sea-ice dynamics in the periods of time prior to and during the cycles of basin-wide fragmentation of the ice cover in the Arctic Ocean is presented. The fractal geometry of the ice-sheets limited by leads and ridges was assessed using the satellite images, while the data on the correlated sea-ice motion were obtained in the research stations "North Pole 32" and "North Pole 33" established on the ice pack. The revealed decrease of the fractal dimension as a result of large-scale fragmentation is consistent with the localization of the fracture process (leads propagation. At the same time, the scaling properties of the distribution of amplitudes of ice-fields accelerations were insensitive to the event of sea-ice fragmentation. The temporal distribution of the accelerations was scale-invariant during "quiet" periods of sea-ice drift but disordered in the period of mechanical perturbation. The period of decorrelated (in time ice-field motion during the important fracture event was interpreted as an inter-level transition in the hierarchic dynamical system. The mechanism of the long-range correlations in the sea-ice cover, including the fracture process, is suggested to be in relation with the self-organized oscillation dynamics inherent in the ice pack.

  5. The Sinking and Spreading of The Antarctic Deep Ice Shelf Water In The Ross Sea Studied By In Situ Observaions and Numerical Modeling

    Science.gov (United States)

    Rubino, A.; Budillon, G.; Pierini, S.; Spezie, G.

    The sinking and spreading of the Deep Ice Shelf Water (DISW) in the Ross Sea are analyzed using in situ observations and the results of a nonlinear, reduced-gravity, frontal layered numerical "plume" model which is able to simulate the motion of a bottom-arrested current over realistic topography. The model is forced by prescribing the thickness of the DISW vein as well as its density structure at the southern model boundary. The ambient temperature and salinity are imposed using hydrographic data acquired by the Italian PNRA-CLIMA project. In the model water of the quiescent ambient ocean is allowed to entrain in the active deep layer due to a simple param- eterization of turbulent mixing. The importance of forcing the model with a realistic ambient density is demonstrated by carrying out a numerical simulation in which the bottom active layer is forced using an idealized ambient density. In a more realis- tic simulation the path and the density structure of the DISW vein flowing over the Challenger Basin are obtained and are found to be in good agreement with data. The evolution of the deep current beyond the continental shelf is also simulated. It provides useful information on the water flow and mixing in a region of the Ross Sea where the paucity of experimental data does not allow for a detailed description of the deep ocean dynamics.

  6. A seasonal study of dissolved cobalt in the Ross Sea, Antarctica: micronutrient behavior, absence of scavenging, and relationships with Zn, Cd, and P

    Directory of Open Access Journals (Sweden)

    M. A. Saito

    2010-12-01

    Full Text Available We report the distribution of cobalt (Co in the Ross Sea polynya during austral summer 2005–2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo was similar to soluble reactive phosphate (PO43−, with dCo and PO43− showing a significant correlation throughout the water column (r2 = 0.87, 164 samples. A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from ~45–85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range of this seasonal variability (~30 pM dCo, with concentrations as low as 20 pM observed in some regions where PO43− was depleted to ~0.1 μM. Both complexed Co, defined as the fraction of dCo bound by strong organic ligands, and labile Co, defined as the fraction of dCo not bound by these ligands, were typically observed in significant concentrations throughout the water column. This contrasts the depletion of labile Co observed in the euphotic zone of other ocean regions, suggesting a much higher bioavailability for Co in the Ross Sea. An ecological stoichiometry of 37.6 μmol Co:mol−1 PO43− calculated from dissolved concentrations was similar to values observed in the subarctic Pacific, but approximately tenfold lower than values in the Eastern Tropical Pacific and Equatorial Atlantic. The ecological stoichiometries for dissolved Co and Zn suggest a greater overall use of Zn relative to Co in the shallow waters of the Ross Sea, with a Co:PO43−/Zn:PO43− ratio of 1:17. Comparison of these observed stoichiometries with values estimated in culture studies suggests that Zn is a key micronutrient that likely influences phytoplankton diversity in the Ross

  7. Variability of scaling time series in the Arctic sea-ice drift dynamics

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2010-02-01

    Full Text Available The motion of an individual ice floe in the Arctic Ocean was monitored at the Russian research station North Pole 35 established on the ice pack in 2008. The ice floe speed (V was found to be correlated with wind speed (v in main features, such as the positions of maxima and minima of V and v. However, the fine structure of the V-variation cannot be explained by the wind forcing alone. There were periods of time when the floe drift was affected by the interactions of ice floes between each other or by the periodical forcing due to either the Coriolis inertia effect or the tidal activity. These data were compared with the "waiting times" statistics that are the distributions of time intervals between subsequent, sufficiently strong changes in the kinetic energy of drifting ice floe. These distributions were measured in several time windows differing in the average wind speed and wind direction, and/or in the mechanical state of the ice pack. The distribution functions N (t>τ, where N is the number of successive events of energy change separated by the time interval t that exceeds τ, constructed in different time windows demonstrate fractal or a multifractal nature of the time series during motion in the consolidated ice pack but were truly random when the ice floe drifted in the highly fragmented sea ice. The latter result shows the existence of a relationship between the long-range mechanical interactions in the pack and long-term memory (time scaling behaviour of the sea-ice motion.

  8. Provenance of a prominent sediment drift on the northern slope of the South China Sea

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The sedimentation rate of the sediment drift in the southeast of Dongsha Islands is as high as 49 cm/ka in the last 1.05 Ma. Although the sedimentation rate changes with time, the con tents of rare elements of the sediments remain almost the same, indicating that the source area of the sediments has been constant with time. On the triangular diagrams of La-Th-Sc and Th-Sc-Zr/10, the samples from the southeast of Dongsha Islands fall within the continental island arc field, overlapping the samples from Taiwan, while the samples from the Pearl River, those from the west of the Philippines that contain volcanic material, are separated from them. This indicates that the sediments from the southeast of Dongsha Islands have a close relationship to those from Taiwan in terms of provenance. In fact, the sediments on the northern slope of the South China Sea were derived from northeast direction, as well as from Taiwan, most probably transported from Taiwan through Penghu channel into the South China Sea. The terrigenous part of the deep-sea sediments in the north of the South China Sea was provided by different sources.

  9. Antarctica - Ross Ice Shelf

    Science.gov (United States)

    1990-01-01

    This color picture of Antarctica is one part of a mosaic of pictures covering the entire polar continent taken during the hours following Galileo's historic first encounter with its home planet. The view shows the Ross Ice Shelf to the right and its border with the sea. An occasional mountain can be seen poking through the ice near the McMurdo Station. It is late spring in Antarctica, so the sun never sets on the frigid, icy continent. This picture was taken about 6:20 p.m. PST on December 8, 1990. From top to bottom, the frame looks across about half of Antarctica.

  10. Interactions between Arctic sea ice drift, concentration and thickness modeled by NEMO-LIM3 at different resolutions

    Science.gov (United States)

    Docquier, David; Massonnet, François; Raulier, Jonathan; Lecomte, Olivier; Fichefet, Thierry

    2016-04-01

    Sea ice concentration and thickness have substantially decreased in the Arctic since the beginning of the satellite era. As a result, mechanical strength has decreased allowing more fracturing and leading to increased sea ice drift. However, recent studies have highlighted that the interplay between sea ice thermodynamics and dynamics is poorly represented in contemporary global climate model (GCM) simulations. Thus, the considerable inter-model spread in terms of future sea ice extent projections could be reduced by better understanding the interactions between drift, concentration and thickness. This study focuses on the results coming from the global coupled ocean-sea ice model NEMO-LIM3 between 1979 and 2012. Three different simulations are forced by the Drakkar Forcing Set (DFS) 5.2 and run on the global tripolar ORCA grid at spatial resolutions of 0.25, 1° and 2°. The relation between modeled sea ice drift, concentration and thickness is further analyzed, compared to observations and discussed in the framework of the above-mentioned poor representation. It is proposed as a process-based metric for evaluating model performance. This study forms part of the EU Horizon 2020 PRIMAVERA project aiming at developing a new generation of advanced and well-evaluated high-resolution GCMs.

  11. Variations in the drift of larval cod ( Gadus morhua L.) in the Baltic Sea : combining field observations and modelling

    DEFF Research Database (Denmark)

    Voss, R.; Hinrichsen, H.H.; St. John, Michael

    1999-01-01

    Coupled three-dimensional (3-D) physical oceanographic modelling and field sampling programmes were carried out in May 1988 and August 1991 to investigate the potential drift of larval cod (Gadus morhua L.) in the Bornholm Basin of the Baltic Sea. The goals were to predict the transport of cod la...

  12. Modelling surface drifting of buoys during a rapidly-moving weather front in the Gulf of Finland, Baltic Sea

    Science.gov (United States)

    Gästgifvars, Maria; Lauri, Hannu; Sarkanen, Annakaisa; Myrberg, Kai; Andrejev, Oleg; Ambjörn, Cecilia

    2006-12-01

    The Gulf of Finland is an elongated estuary located in the north-eastern extremity of the Baltic Sea. This semi-enclosed sea-area is subject to heavy sea traffic, and is one of the main risk areas for oil accidents in the Baltic. The continuous development and validation of operational particle drift and oil-spill forecasting systems is thus seen to be essential for this sea-area. Here, the results of a three-day drift experiment in May 2003 are discussed. The field studies were performed using GPS-positioned surface floating buoys. The aim of this paper is to evaluate how well models can reproduce the drift of these buoys. Model simulations, both in forecast and hindcast modes, were carried out by three different 3D hydrodynamic models, the results of which are evaluated by comparing the calculated drifts with observations. These models were forced by HIRLAM (High Resolution Limited Area Model) and ECMWF (European Centre for Medium-Range Weather Forecasts) meteorological forecast fields. The simulated drift of the buoys showed a good agreement with observations even when, during the study period, a rapidly-changing wind situation was observed to affect the investigation area; in this situation the winds turned about 100 degrees in half an hour. In such a case it is a very complicated task to forecast the drifters' routes: there is a need to regularly update the meteorological forcing fields and to use these regularly-updated fields throughout the simulations. It is furthermore recommended that forecasts should be made using several circulation models and several meteorological forecasts, in order to get an overview of the accuracy of the forecasted drifts and related differences in between the forecasts.

  13. Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave-current coupled model

    Science.gov (United States)

    Tao, Xie; Shang-Zhuo, Zhao; William, Perrie; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-06-01

    To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave-current model is derived, based on the mechanism of wave-current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave-current interaction effect of the ocean current is much stronger than that of the nonlinear wave-wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service.

  14. Seeking an optimal algorithm for a new satellite-based Sea Ice Drift Climate Data Record : Motivations, plans and initial results from the ESA CCI Sea Ice project

    DEFF Research Database (Denmark)

    Lavergne, T.; Dybkjær, Gorm; Girard-Ardhuin, Fanny

    relevant satellite and “ground-truth” data, building the Round-Robin Data Package for testing the algorithms, and finally selection of the most promising algorithm(s) for processing of a new sea ice drift climate dataset. Specific efforts are dedicated to the definition of per-grid-cell uncertainties...

  15. Seeking an optimal algorithm for a new satellite-based Sea Ice Drift Climate Data Record : Motivations, plans and initial results from the ESA CCI Sea Ice project

    DEFF Research Database (Denmark)

    Lavergne, T.; Dybkjær, Gorm; Girard-Ardhuin, Fanny

    relevant satellite and “ground-truth” data, building the Round-Robin Data Package for testing the algorithms, and finally selection of the most promising algorithm(s) for processing of a new sea ice drift climate dataset. Specific efforts are dedicated to the definition of per-grid-cell uncertainties...

  16. New determinations of 40Ar/39Ar isotopic ages and flow volumes for Cenozoic volcanism in the Terror Rift, Ross Sea, Antarctica

    Science.gov (United States)

    Rilling, S.; Mukasa, S.; Wilson, T.; Lawver, L.; Hall, C.

    2009-12-01

    This study provides new determinations of 40Ar/39Ar isotopic ages and flow volumes for submarine and subaerial Neogene volcanism developed within the Terror Rift, Ross Sea, Antarctica, the youngest segment of the West Antarctic Rift System. The study is based on the first dredged samples from seven seamounts north of Ross Island, as well as new data from Franklin and Beaufort Islands. The sampled foidite and basanitic lavas range in age from Quaternary (90 ± 66 ka) on a small seamount ˜10 km north of Franklin Island to 6.80 ± 0.05 Ma on Beaufort Island. These ages are consistent with ages of volcanism in both the Melbourne and Erebus Volcanic Provinces and significantly expand the documented area of Neogene magmatism in Victoria Land. There is no geographic progression of volcanism through time, but volcanism was voluminous in the Pliocene and particularly widespread during the Pleistocene. Two of the dredges sampled edifices comprised of less than 0.2 km3 of volcanic materials. The largest seamount in the study area has 58.8 km3 of volcanic material and represents growth over a period of several thousand years. Estimated minimum eruption rates range from 2 × 10-4 km3 y-1 to 2 × 10-3 km3 y-1, consistent with rates proposed for other rift systems and nearby Mt. Erebus. Recent estimates of extension magnitude for the Terror Rift correspond to minimal decompression of only 0.10 to 0.22 GPa and therefore limited melt output of a typical peridotite source.

  17. Mesoscale and high-frequency variability of macroscopic particles (> 100 μm) in the Ross Sea and its relevance for late-season particulate carbon export

    Science.gov (United States)

    Bochdansky, Alexander B.; Clouse, Melissa A.; Hansell, Dennis A.

    2017-02-01

    The Ross Sea plays a major role in the transfer of organic carbon from the surface into the deep sea due to the combination of high seasonal productivity and Antarctic bottom water formation. Here we present a particle inventory of the Ross Sea based on a combined deployment of a video particle profiler (VPP) and a high-resolution digital holographic microscope (DIHM). Long-distance (100 s of kilometers) and short-distance (10 s of kilometers) sections showed high variability of particle distributions that co-varied with the density structure of the water column. Particle export was apparent at sites of locally weakened pycnoclines, likely an indirect effect of nutrient mixing into the surface layer and local blooms that lead to export. Particle volume abundances at 200-300 m depth were highly correlated with particle volume abundances in the upper mixed layer (export rather than lateral advection. Phaeocystis antarctica (Haptophyta) colonies that were initially retained in the mixed layer sank below the euphotic zone within a period of two weeks. Fine-scale analysis at a resolution < 1 m revealed a significantly overdispersed (i.e., highly patchy) environment in all casts. Patchiness, as determined by the Lloyd index of patchiness and the Index of Aggregation, increased in and below the pycnocline presumably due to aggregation of particles while accumulating on density gradients. In contrast, particles in the upper mixed layer and in the nepheloid layers were more randomly distributed. In 40 of the 84 VPP depth profiles, a periodicity of particle peaks ranged from 10 to 90 m with a mode of 30 m, which can be regarded as the "relevant scale" or "characteristic patch size" of the vertical distribution of particles. While chlorophyll fluorescence and particle mass determined by VPP were significantly correlated at higher particle abundances, the relationship changed from cast to cast, reflecting changes in the relative contribution of fresh phytoplankton to total

  18. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the JAMES CLARK ROSS in the Arctic Ocean, Barents Sea and others from 2012-11-15 to 2013-08-16 (NODC Accession 0115256)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115256 includes chemical, meteorological, physical and underway - surface data collected from JAMES CLARK ROSS in the Arctic Ocean, Barents Sea,...

  19. Sea ice drift from Sentinel-1 SAR imagery using open source feature tracking

    Science.gov (United States)

    Muckenhuber, Stefan; Korosov, Anton; Sandven, Stein

    2016-04-01

    A computational efficient, open source feature tracking algorithm, called ORB, is adopted and tuned for sea ice drift retrieval from Sentinel-1 SAR images. The best suitable setting and parameter values have been found using four representative Sentinel-1 image pairs. A new quality measure for feature tracking algorithms is introduced utilising the distribution of the resulting vector field. The performance of the algorithm is compared with two other feature tracking algorithms (SIFT and SURF). Applied on a test image pair acquired over Fram Strait, the tuned ORB algorithm produces the highest number of vectors (6920, SIFT: 1585 and SURF: 518) while being computational most efficient (66 s, SIFT: 182 s and SURF: 99 s using a 2,7 GHz processor with 8 GB memory). For validation purpose, 350 manually drawn vectors have been compared with the closest calculated vectors and the resulting root mean square distance is 609.9 m (equivalent to 7.5 pixel). All test image pairs show a significant better performance of the HV channel. On average, around 4 times more vectors have been found using HV polarisation. All software requirements necessary for applying the presented feature tracking algorithm are open source to ensure a free and easy implementation.

  20. Ross og demokratiet

    DEFF Research Database (Denmark)

    Svensson, Palle

    2006-01-01

    En kritisk analyse af Alf Ross' teori om demokrati på grundlag af Roberty A. Dahl's begrebsapparat.......En kritisk analyse af Alf Ross' teori om demokrati på grundlag af Roberty A. Dahl's begrebsapparat....

  1. 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.

  2. Ross - for altid?

    DEFF Research Database (Denmark)

    Blume, Peter Erik

    2011-01-01

    Med baggrund i Jens Ewalds bog om Alf Ross omtaler artiklen en række de problemstillinger, som bogen behandler, samt vurderer den betydning, Ross har haft og måske fortsat har. Afslutningsvis betones den juridiske biografis betydning.......Med baggrund i Jens Ewalds bog om Alf Ross omtaler artiklen en række de problemstillinger, som bogen behandler, samt vurderer den betydning, Ross har haft og måske fortsat har. Afslutningsvis betones den juridiske biografis betydning....

  3. A Possible Feedback Mechanism Involving the Arctic Freshwater,the Arctic Sea Ice, and the North Atlantic Drift

    Institute of Scientific and Technical Information of China (English)

    Odd Helge OTTER(A); Helge DRANGE

    2004-01-01

    Model studies point to enhanced warming and to increased freshwater fluxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined effect of increased freshwater input to the Arctic Ocean and Arctic warming--the latter manifested as a gradual melting of the Arctic sea ice--is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runoff, and a third more extreme case, where the river runoff is five times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5-2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift.Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensified Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.

  4. Fractionation distribution and preliminary ecological risk assessment of As, Hg and Cd in ornithogenic sediments from the Ross Sea region, East Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Chuangneng [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Liu, Xiaodong, E-mail: ycx@ustc.edu.cn [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Nie, Yaguang [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Emslie, Steven D. [Department of Biology and Marine Biology, University of North Carolina Wilmington, 601S. College Road, Wilmington, NC 28403 (United States)

    2015-12-15

    To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. Organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation. - Highlights: • Residual As holds a dominant position in ornithogenic sediments. • Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions. • Exchangeable Cd occupies a considerable proportion in ornithogenic sediments. • TOC is the main factor controlling the mobility of Hg and Cd in studied sediments.

  5. Persistent organic pollutants (POPs) in the atmosphere of coastal areas of the Ross Sea, Antarctica: Indications for long-term downward trends.

    Science.gov (United States)

    Pozo, Karla; Martellini, Tania; Corsolini, Simonetta; Harner, Tom; Estellano, Victor; Kukučka, Petr; Mulder, Marie D; Lammel, Gerhard; Cincinelli, Alessandra

    2017-07-01

    Passive air samplers were used to evaluate long-term trends and spatial distribution of trace organic compounds in Antarctica. Duplicate PUF disk samplers were deployed at six automatic weather stations in the coastal area of the Ross sea (East Antarctica), between December 2010 and January 2011, during the XXVI Italian Scientific Research Expedition. Among the investigated persistent organic compounds, Hexachlorobenzene was the most abundant, with air concentrations ranging from 0.8 to 50 pg m(-3). In general, the following decreasing concentration order was found for the air samples analyzed: HCB > PeCB > PCBs > DDTs > HCHs. While HCB concentrations were in the same range as those reported in the atmosphere of other Antarctic sampling areas and did not show a decline, HCHs and DDTs levels were lower or similar to those determined one or two decades ago. In general, the very low concentrations reflected the pristine state of the East Antarctica air. Backward trajectories indicated the prevalence of air masses coming from the Antarctic continent. Local contamination and volatilization from ice were suggested as potential sources for the presence of persistent organic pollutants in the atmosphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. The relative roles of modified circumpolar deep water and benthic sources in supplying iron to the recurrent phytoplankton blooms above Pennell and Mawson Banks, Ross Sea, Antarctica

    Science.gov (United States)

    Hatta, Mariko; Measures, Chris I.; Lam, Phoebe J.; Ohnemus, Daniel C.; Auro, Maureen E.; Grand, Maxime M.; Selph, Karen E.

    2017-02-01

    The role that dissolved iron (dFe) rich Circumpolar Deep Water (CDW) might play in sustaining the consistently observed discrete patches of high chlorophyll biomass over Pennell Bank (PB) and Mawson Bank (MB) in the Ross Sea, was investigated during January/February 2011. Over a 26-day period, hydrographic and trace metal clean water sampling was carried out adjacent to both of these banks, in some cases repeatedly. Particulate sampling was also accomplished at selected stations by in situ pumping. The results indicate that the dFe content of the CDW is in fact reduced by on-shelf mixing with Antarctic Surface Water as it transitions into modified CDW (MCDW). Our stations above PB, where the maximum bloom is encountered, show no evidence of MCDW presence. In contrast, above MB, where there is a smaller persistent bloom, MCDW was observed. Although both of these stations displayed the imprint of sedimentary Fe input connected to the strong tidal cycles above the banks, the stronger near-bottom density gradient that MCDW produces appears to contribute to reduced vertical mixing of the sedimentary source. Thus, ironically, the presence of MCDW may be hindering the Fe supply to the surface waters, rather than being the source, as originally hypothesized.

  7. Carbon fluxes and export in the northern and middle Atlantic Sea measured with drifting sediment traps

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, J-C; Fowler, S; Hamilton, T; Heilmann, J P; LaRosa, J; Carroll, M

    2000-07-26

    In July 1993 and June 1995 drifting sediment traps were deployed near the Po outflow, in the coastal zone and in the Jabuka Pit in order to obtain quantitative information on the vertical flux of particulate material and export of organic carbon in the Northern and Middle Adriatic Sea. During these periods and in July 1994, the standing stock of carbon and nitrogen in the water column were also estimated. Carbon and nitrogen concentrations were higher in the north with a mean of 266 {micro}g C l{sup -1} in surface waters as compared to 92 {micro}g C l{sup -1} in Middle Adriatic; maximum concentrations were associated to the less-saline surface-subsurface waters in the north and to the chlorophyll a maximum in the Middle Adriatic. Organic carbon flux was roughly five times higher near the Po than in the more oligotrophic waters of the central region, with overall values (0.8 to 11.5 mg m{sup -2} d{sup -1}) being low compared to the open Northwestern Mediterranean. Comparison with primary production measurements yielded estimates of carbon export (f-ratio) of 4.7 and 3.4% in the Po and Pit stations, respectively, in 1993 and of 1.6 and 3.6% in the central part of the Adriatic in 1995. These consistently low values suggest enhanced carbon recycling in the upper water column, even in regions characterized by different production and organic flux regimes. Zooplankton fecal pellets were important conveyors of organic carbon in this region; particularly those produced by fishes in the North and coastal sites.

  8. Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

    DEFF Research Database (Denmark)

    Munk, Peter; Hansen, Michael Møller; Maas, Gregory E.;

    2010-01-01

    and steering their drift. The majority of the more westerly distributed American eel larvae are likely to follow a westerly/northerly drift route entrained in the Antilles/Florida Currents. European eel larvae are generally believed to initially follow the same route, but their more easterly distribution close...

  9. Larval growth and drift pattern and the separation of herring spawning groups in the North Sea

    DEFF Research Database (Denmark)

    Munk, Peter; Christensen, Villy

    1990-01-01

    from west of Scotland and around the Orkney/Shetland Isles, whereas the relationship is reversed in the juveniles. In the investigated period, larval drift routes exhibited the same trends from year to year, the drift of the northerly spawned larvae being the most variable. Thus, changes...

  10. Observing Physical and Biological Drivers of pH and O2 in a Seasonal Ice Zone in the Ross Sea Using Profiling Float Data

    Science.gov (United States)

    Briggs, E.; Martz, T. R.; Talley, L. D.; Mazloff, M. R.

    2015-12-01

    Ice cover has strong influence over gas exchange, vertical stability, and biological production which are critical to understanding the Southern Ocean's central role in oceanic biogeochemical cycling and heat and carbon uptake under a changing climate. However the relative influence of physical versus biological processes in this hard-to-study region is poorly understood due to limited observations. Here we present new findings from a profiling float equipped with biogeochemical sensors in the seasonal ice zone of the Ross Sea capturing, for the first time, under-ice pH profile data over a two year timespan from 2014 to the present. The relative influence of physical (e.g. vertical mixing and air-sea gas exchange) and biological (e.g. production and respiration) drivers of pH and O2 within the mixed layer are explored during the phases of ice formation, ice cover, and ice melt over the two seasonal cycles. During the austral fall just prior to and during ice formation, O2 increases as expected due to surface-layer undersaturation and enhanced gas exchange. A small increase in pH is also observed during this phase, but without a biological signal in accompanying profiling float chlorophyll data, which goes against common reasoning from both a biological and physical standpoint. During the phase of ice cover, gas exchange is inhibited and a clear respiration signal is observed in pH and O2 data from which respiration rates are calculated. In the austral spring, ice melt gives rise to substantial ice edge phytoplankton blooms indicated by O2 supersaturation and corresponding increase in pH and large chlorophyll signal. The influence of the duration of ice cover and mixed layer depth on the magnitude of the ice edge blooms is explored between the two seasonal cycles.

  11. Poly-brominated diphenyl-ethers (PBDEs) and other persistent organic pollutants in blood of penguins from the Ross Sea (Antarctica)

    Energy Technology Data Exchange (ETDEWEB)

    Corsolini, S.; Ademollo, N.; Mariottini, M.; Focardi, S. [Universita degli Studi di Siena, Siena (Italy)

    2004-09-15

    Polychlorobiphenyls (PCBs), hexachlorobenzene (HCB), polybrominated diphenyl ethers (PBDEs) and dichlorodiphenyl-dichloro ethane (pp'-DDE) including its isomers and metabolites are known as POPs very well. POPs are particularly hazardous to wildlife not only because they are toxic but because they are persistent and distributed on global scale. Polybrominated diphenyl ethers (PBDEs) are a class of POPs used worldwide as flame retardants with an increasing trend in the market demand (67.4 ktons in 2001), but with some restrictions in their usage in Europe. PBDEs are hydrophobic, highly soluble in lipids, resistant to biodegradation and have similar behavior to polychlorinated biphenyls (PCBs) in aquatic and terrestrial ecosystems. Their bioaccumulation and biomagnification properties, as well their global increasing presence, have already been reported by many authors. PBDEs have been detected in remote Arctic regions10 that seem to be their final sink. PBDEs show acute toxicity and a prolonged exposure can affect the function of thyroid and cause neurodevelopmental disorders and estrogenic and hepatic effects. Furthermore, a synergic effect with dioxin-like compounds or other POPs cannot be excluded. The two aims of this study are: (1) to evaluate accumulation levels and patterns of PCBs, PBDEs and chlorinated pesticides in blood samples of the Adelie penguin, Pygoscelis adeliae, the Emperor penguin, Aptenodytes forsteri and the South Polar skua, Cataracta maccormicki from three sites in the Ross Sea (Antarctica); (2) to assess the suitability of blood for the detection of POP residues in supposedly low contaminated organisms that live in protected/ecologically sensitive areas.

  12. The impact of glacier retreat from the Ross Sea on local climate: Characterization of mineral dust in the Taylor Dome ice core, East Antarctica

    Science.gov (United States)

    Aarons, S. M.; Aciego, S. M.; Gabrielli, P.; Delmonte, B.; Koornneef, J. M.; Wegner, A.; Blakowski, M. A.

    2016-06-01

    Recent declines in ice shelf and sea ice extent experienced in polar regions highlight the importance of evaluating variations in local weather patterns in response to climate change. Airborne mineral particles (dust) transported through the atmosphere and deposited on ice sheets and glaciers in Antarctica and Greenland can provide a robust set of tools for resolving the evolution of climatic systems through time. Here we present the first high time resolution radiogenic isotope (strontium and neodymium) data for Holocene dust in a coastal East Antarctic ice core, accompanied by rare earth element composition, dust concentration, and particle size distribution during the last deglaciation. We aim to use these combined ice core data to determine dust provenance, with variations indicative of shifts in either dust production, sources, and/or transport pathways. We analyzed a series of 17 samples from the Taylor Dome (77°47‧47″S, 158°43‧26″E) ice core, 113-391 m in depth from 1.1-31.4 ka. Radiogenic isotopic and rare earth element compositions of dust during the last glacial period are in good agreement with previously measured East Antarctic ice core dust records. In contrast, the Holocene dust dataset displays a broad range in isotopic and rare earth element compositions, suggesting a shift from long-range transported dust to a more variable, local input that may be linked to the retreat of the Ross Ice Shelf during the last deglaciation. Observed changes in the dust cycle inferred from a coastal East Antarctic ice core can thus be used to infer an evolving local climate.

  13. China's first intermediate resolution multi-channel seismic survey in the northern Victoria Land Basin and Terror Rift, Ross Sea, Antarctica

    Science.gov (United States)

    Shen, Zhongyan; Gao, Jinyao; Zhang, Tao; Wang, Wei; Ding, Weifeng; Zhang, Sheng

    2017-04-01

    The West Antarctic Rift System (WARS) represents one of the largest active continental rift systems on Earth and is less well known than other rift systems because it is largely covered by thick ice. The Terror Rift (TR), superimposing on the Victoria Land Basin (VLB) in the western Ross Sea, is identified as the most recent deformational zone of the WARS, thus will provide knowledge of the active deformation process of the WARS. The structure and kinematics of the TR is under debate. Originally, the TR was thought to consist of two parts: the Discovery Graben and the magmatically-intruded Lee Arch. New denser seismic grid in the middle and southern segments of the TR revealed a different structure of the Lee Arch while the northern segment of the TR is not well studied. The glacial history of the VLB/TR region is another attractive issue to the geologists since this area records the behavior information of EAIS and WAIS. In the southern part of the VLB, especially in the McMurdo Sound, the framework of the glacial history is well established after several deep cores which recovery the whole stratigraphic sequences since the onset of the glaciation. However, the glacial history of the northern part of the VLB/TR is less well studied and here we emphasize its importance because the northern part of the VLB/TR is a link between the well-studied southern VLB and the sediment-well-preserved Northern Basin. During the 32nd Chinese National Antarctic Research Expedition, on the board of the RV XueLong, we collected intermediate resolution multi-channel seismic reflection data in the northern VLB/TR. These data will establish new constraints on the timing of deformation, structure and kinematics of the TR, and the history of the EAIS and WAIS.

  14. Method to characterize directional changes in Arctic sea ice drift and associated deformation due to synoptic atmospheric variations using Lagrangian dispersion statistics

    Science.gov (United States)

    Lukovich, Jennifer V.; Geiger, Cathleen A.; Barber, David G.

    2017-07-01

    A framework is developed to assess the directional changes in sea ice drift paths and associated deformation processes in response to atmospheric forcing. The framework is based on Lagrangian statistical analyses leveraging particle dispersion theory which tells us whether ice drift is in a subdiffusive, diffusive, ballistic, or superdiffusive dynamical regime using single-particle (absolute) dispersion statistics. In terms of sea ice deformation, the framework uses two- and three-particle dispersion to characterize along- and across-shear transport as well as differential kinematic parameters. The approach is tested with GPS beacons deployed in triplets on sea ice in the southern Beaufort Sea at varying distances from the coastline in fall of 2009 with eight individual events characterized. One transition in particular follows the sea level pressure (SLP) high on 8 October in 2009 while the sea ice drift was in a superdiffusive dynamic regime. In this case, the dispersion scaling exponent (which is a slope between single-particle absolute dispersion of sea ice drift and elapsed time) changed from superdiffusive (α ˜ 3) to ballistic (α ˜ 2) as the SLP was rounding its maximum pressure value. Following this shift between regimes, there was a loss in synchronicity between sea ice drift and atmospheric motion patterns. While this is only one case study, the outcomes suggest similar studies be conducted on more buoy arrays to test momentum transfer linkages between storms and sea ice responses as a function of dispersion regime states using scaling exponents. The tools and framework developed in this study provide a unique characterization technique to evaluate these states with respect to sea ice processes in general. Application of these techniques can aid ice hazard assessments and weather forecasting in support of marine transportation and indigenous use of near-shore Arctic areas.

  15. Ross Ice Shelf, Antarctic Ice and Clouds

    Science.gov (United States)

    1991-01-01

    In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

  16. Fast- and drift-ice communities in the Bothnian Bay and the impact of UVA radiation on the Baltic Sea ice ecology

    OpenAIRE

    Piiparinen, Jonna

    2011-01-01

    The aim of this thesis was to study ecology of Baltic Sea ice from two perspectives. In the first two studies, sea-ice ecology from riverine-influenced fast ice to drift ice in the Bothnian Bay was investigated, whereas the last two studies focus on the sensitivity of sea-ice bacteria and algae to UVA examined in situ. The seasonal sea ice cover is one of the main characteristics of the Baltic Sea, and despite the brackish parental water, the ice structure is similar to polar ice with sa...

  17. A method for assessing the physical recovery of Antarctic desert pavements following human-induced disturbances: a case study in the Ross Sea region of Antarctica.

    Science.gov (United States)

    O'Neill, Tanya A; Balks, Megan R; López-Martínez, Jerónimo; McWhirter, Judi L

    2012-12-15

    With increasing visitor numbers an understanding of the impacts of human activities in Antarctic terrestrial environments has become important. The objective of this study was to develop a means for assessing recovery of the ground surface desert pavement following physical disturbance. A set of 11 criteria were identified to assess desert pavement recovery. Assessed criteria were: embeddedness of surface clasts; impressions of removed clasts; degree of clast surface weathering; % overturned clasts; salt on underside of clasts; development of salt coatings; armouring per m(2); colour contrast; evidence of subsidence/melt out; accumulation of salt on cut surfaces; and evidence of patterned ground development. Recovery criteria were assigned a severity/extent rating on a scale from zero to four, zero being highly disturbed, and four being undisturbed. A relative % recovery for each criteria was calculated for each site by comparison with a nearby undisturbed control area, and an overall Mean Recovery Index (MRI) was assigned to each pavement surface. To test the method, 54 sites in the Ross Sea region of Antarctica were investigated including areas disturbed by: bulldozer scraping for road-fill, contouring for infrastructure, geotechnical investigations, and experimental treading trial sites. Disturbances had occurred at timescales ranging from one week to 50 years prior to assessment. The extent of desert pavement recovery at the sites investigated in this study was higher than anticipated. Fifty of the 54 sites investigated were in an intermediate, or higher, stage of desert pavement recovery, 30 sites were in an advanced stage of recovery, and four sites were indistinguishable from adjacent control sites (MRI = 100%). It was found that active surfaces, such as the gravel beach deposits at the Greenpeace World Park Base site at Cape Evans, the aeolian sand deposits at Bull Pass, and the alluvial fan deposits of the Loop Moraine field campsite, recovered relatively

  18. Ross og erkendelsesteorien

    DEFF Research Database (Denmark)

    Holtermann, Jakob von Holderstein

    2006-01-01

    Et argument for at den logiske positivismes notoriske problemer ikke - som almindeligt antaget - har gjort Alf Ross' retsfilosofi forældet. Mere konkret påvises det at Ross i virkeligheden passer bedre sammen med den empiriske erkendelsesteori der har rejst sig på den logiske positivismes ruiner....

  19. Open-source feature-tracking algorithm for sea ice drift retrieval from Sentinel-1 SAR imagery

    Science.gov (United States)

    Muckenhuber, Stefan; Andreevich Korosov, Anton; Sandven, Stein

    2016-04-01

    A computationally efficient, open-source feature-tracking algorithm, called ORB, is adopted and tuned for sea ice drift retrieval from Sentinel-1 SAR (Synthetic Aperture Radar) images. The most suitable setting and parameter values have been found using four Sentinel-1 image pairs representative of sea ice conditions between Greenland and Severnaya Zemlya during winter and spring. The performance of the algorithm is compared to two other feature-tracking algorithms, namely SIFT (Scale-Invariant Feature Transform) and SURF (Speeded-Up Robust Features). Having been applied to 43 test image pairs acquired over Fram Strait and the north-east of Greenland, the tuned ORB (Oriented FAST and Rotated BRIEF) algorithm produces the highest number of vectors (177 513, SIFT: 43 260 and SURF: 25 113), while being computationally most efficient (66 s, SIFT: 182 s and SURF: 99 s per image pair using a 2.7 GHz processor with 8 GB memory). For validation purposes, 314 manually drawn vectors have been compared with the closest calculated vectors, and the resulting root mean square error of ice drift is 563 m. All test image pairs show a significantly better performance of the HV (horizontal transmit, vertical receive) channel due to higher informativeness. On average, around four times as many vectors have been found using HV polarization. All software requirements necessary for applying the presented feature-tracking algorithm are open source to ensure a free and easy implementation.

  20. Stable Isotopic signatures of Adélie penguin remains provide long-term paleodietary records in Northern Victoria Land (Ross Sea, Antarctica)

    Science.gov (United States)

    Lorenzini, Sandra; Baroni, Carlo; Fallick, Anthony Edward; Baneschi, Ilaria; Salvatore, Maria Cristina; Zanchetta, Giovanni; Dallai, Luigi

    2010-05-01

    The stable isotopes geochemistry of carbon and nitrogen provides a powerful tools for investigating in animal dietary patterns and shifts during the past. The signature of C and N isotopes provide direct information about the diet of an individual and its dietary patterns, especially when the dietary sources consist of prey from different trophic levels (i.e. different C and N isotopic composition) (DeNiro and Epstein 1978, Minawaga and Wada 1984, Koch et al. 1994, Hobson 1995). By analyzing the isotopic composition of penguin remains, we present a new detailed Adélie penguin (Pygoscelis adeliae) paleodietary record for the area of Terra Nova Bay (Victoria Land, Ross Sea). Adélie penguins primarily feed on fish (mainly the silverfish Pleuragramma antarcticum) and krill (Euphausia superba, Euphausia cristallorophias) (Ainley 2002, Lorenzini et al. 2009) that belonging to two different trophic levels. Consequently, they are characterized by different isotopic signatures. Specifically, we analyzed 13C/12C and 15N/14N ratios of more than one thousand of modern and fossil Adélie penguin eggshell and guano samples collected from ornithogenic soils (penguin guano-formed) dated back to ≈7,200 years BP (Baroni and Orombelli 1994, Lambert et al. 2002, Baroni and Hall 2004, Hall et al. 2006). The expanded database of stable isotope values obtained from Adélie penguin remains define a detailed paleodietary record with an excellent temporal continuity over all the investigated time period. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7200 yrs BP to 2000 yrs BP, δ13C and δ15N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2000 yrs BP, when the δ13C values reveal a mixed diet based on fish and krill consumption. Modern

  1. Sea ice concentration and sea ice drift for the Arctic summer using C- and L-band SAR

    Science.gov (United States)

    Johansson, Malin; Berg, Anders; Eriksson, Leif

    2014-05-01

    The decreasing amount of sea ice and changes from multi-year ice to first year ice within the Arctic Ocean opens up for increased maritime activities. These activities include transportation, fishing and tourism. One of the major threats for the shipping is the presence of sea ice. Should an oil spill occur, the search and rescue is heavily dependent on constant updates of sea ice movements, both to enable a safer working environment and to potentially prevent the oil from reaching the sea ice. It is therefore necessary to have accurate and updated sea ice charts for the Arctic Ocean during the entire year. During the melt season that ice is subject to melting conditions making satellite observations of sea ice more difficult. This period coincides with the peak in marine shipping activities and therefore requires highly accurate sea ice concentration estimates. Synthetic Aperture Radar (SAR) are not hindered by clouds and do not require daylight. The continuous record and high temporal resolution makes C-band data preferable as input data for operational sea ice mapping. However, with C-band SAR it is sometimes difficult to distinguish between a wet sea ice surface and surrounding open water. L-band SAR has a larger penetration depth and has been shown to be less sensitive to less sensitive than C-band to the melt season. Inclusion of L-band data into sea chart estimates during the melt season in particular could therefore improve sea ice monitoring. We compare sea ice concentration melt season observations using Advanced Land Observing Satellite (ALOS) L-band images with Envisat ASAR C-band images. We evaluate if L-band images can be used to improve separation of wet surface ice from open water and compare with results for C-band.

  2. Open-source sea ice drift algorithm for Sentinel-1 SAR imagery using a combination of feature tracking and pattern matching

    Science.gov (United States)

    Muckenhuber, Stefan; Sandven, Stein

    2017-08-01

    An open-source sea ice drift algorithm for Sentinel-1 SAR imagery is introduced based on the combination of feature tracking and pattern matching. Feature tracking produces an initial drift estimate and limits the search area for the consecutive pattern matching, which provides small- to medium-scale drift adjustments and normalised cross-correlation values. The algorithm is designed to combine the two approaches in order to benefit from the respective advantages. The considered feature-tracking method allows for an efficient computation of the drift field and the resulting vectors show a high degree of independence in terms of position, length, direction and rotation. The considered pattern-matching method, on the other hand, allows better control over vector positioning and resolution. The preprocessing of the Sentinel-1 data has been adjusted to retrieve a feature distribution that depends less on SAR backscatter peak values. Applying the algorithm with the recommended parameter setting, sea ice drift retrieval with a vector spacing of 4 km on Sentinel-1 images covering 400 km × 400 km, takes about 4 min on a standard 2.7 GHz processor with 8 GB memory. The corresponding recommended patch size for the pattern-matching step that defines the final resolution of each drift vector is 34 × 34 pixels (2.7 × 2.7 km). To assess the potential performance after finding suitable search restrictions, calculated drift results from 246 Sentinel-1 image pairs have been compared to buoy GPS data, collected in 2015 between 15 January and 22 April and covering an area from 80.5 to 83.5° N and 12 to 27° E. We found a logarithmic normal distribution of the displacement difference with a median at 352.9 m using HV polarisation and 535.7 m using HH polarisation. All software requirements necessary for applying the presented sea ice drift algorithm are open-source to ensure free implementation and easy distribution.

  3. Modeling and Control for Dynamic Positioned Marine Vessels in Drifting Managed Sea Ice

    Directory of Open Access Journals (Sweden)

    Øyvind Kåre Kjerstad

    2014-10-01

    Full Text Available This paper presents a development framework for dynamic positioning control systems for marine vessels in managed ice. Due to the complexity of the vessel-ice and ice-ice interactions a configurable high fidelity numerical model simulating the vessel, the ice floes, the water, and the boundaries is applied. The numerical model is validated using experimental data and coupled with a control application incorporating sensor models, control systems, actuator models, and other external dynamics to form a closed loop development platform. The ice drift reversal is simulated by moving the positioning reference frame in an elliptic trajectory, rather than moving each individual ice floe. A control plant model is argued, and a control system for managed ice is proposed based on conventional open water design methods. A case study shows that dynamic positioning in managed ice is feasible for some moderate ice conditions.

  4. Ontogenetic development of migration: Lagrangian drift trajectories suggest a new paradigm for sea turtles

    DEFF Research Database (Denmark)

    Hays, Graeme C.; Fossette, Sabrina; Katselidis, Kostas A.

    2010-01-01

    Long distance migration occurs in a wide variety of taxa including birds, insects, fishes, mammals and reptiles. Here, we provide evidence for a new paradigm for the determinants of migration destination. As adults, sea turtles show fidelity to their natal nesting areas and then at the end...

  5. Bottom water production variability in the Ross Sea slope during the Late-Pleistocene-Holocene as revealed by benthic foraminifera and sediment geochemistry

    Science.gov (United States)

    Asioli, A.; Langone, L.; Tateo, F.; Giannossi, M. L.; Giglio, F.; Summa, V.; Piva, A.; Ridente, D.; Trincardi, F.

    2009-04-01

    The Antarctic area produces bottom waters that ventilate the vast majority of the deep basins in the rest of the world ocean. The rate of formation in the source area and the strength of these cold bottom waters affect their flow toward the equator and are key factors affecting the Global Thermohaline Circulation during modern and past climate conditions. We present the results of a multidisciplinary study carried out on a core collected in 2377m of water depth on the slope off the Drygalski Basin (Ross Sea), along the modern path of the bottom waters. The goal of this research is to detect a qualitative signal of possible changes in the rate of bottom water production during the Late Pleistocene-Holocene by integrating micropaleontological and geochemical proxies. The micropaleontological signal is represented by the quantitative and qualitative variations of the agglutinated benthic foraminifera assemblages, while the amount of TOC, nitrogen, δ13C, δ15N, biogenic silica, CaCO3 in the sediment, along with the bulk rock mineralogy, provide information on the paleoproductivity and allow reconstruction of changes in the paleocirculation. The chronology is supported by 14C AMS datings on organic matter. Although this study is still in progress, the results obtained allow the following observations: 1) the Holocene sequence includes a major turnover around 8-8.5 calib kyr BP, leading to reduced nutrient utilization, probably reflecting an increased nutrient supply induced by an enhanced Upper Circumpolar Deep Water upwelling; 2) within this general context, the total concentration of benthic foraminifera preserved in the fossil component records millennial scale cycles of variable amplitude after 8.5 calib kyr BP and to present time. This oscillatory trend is paralleled by other parameters, such as the magnetic susceptibility, the dry density, the sheet silicates and the δ15N; 3) minima in foraminifera concentration reflect relatively increased dissolution, weaker

  6. Evolution of a high-latitude sediment drift inside a glacially-carved trough based on high-resolution seismic stratigraphy (Kveithola, NW Barents Sea)

    Science.gov (United States)

    Rebesco, Michele; Özmaral, Asli; Urgeles, Roger; Accettella, Daniela; Lucchi, Renata G.; Rüther, Denise; Winsborrow, Monica; Llopart, Jaume; Caburlotto, Andrea; Lantzsch, Hendrik; Hanebuth, Till J. J.

    2016-09-01

    Kveithola is a glacially-carved, E-W trending trough located in the NW Barents Sea, an epicontinental shelf sea of the Arctic Ocean located off northern Norway and Russia. A set of confined sediment drifts (the "Kveithola Drift") is located in the inner part of the trough. In general, drift deposits are commonly characterized by high lateral continuity, restricted occurrence of hiatuses and relatively high accumulation rates, and thus represent excellent repositories of paleo-environmental information. We provide for the first time a detailed morphological and seismostratigraphic insight into this sediment drift, which is further supported by some preliminary lithological and sedimentological analyses. The complex morphology of the drift, imaged by combining all available multibeam data, includes a main and a minor drift body, two drift lenses in the outer part of the trough, more or less connected drift patches in the innermost part and small perched sediment patches in a structurally-controlled channel to the north. The seismic (PARASOUND) data show that the main and minor drift bodies are mainly well-stratified, characterized by sub-parallel reflections of moderate to high amplitude and good lateral continuity. The reflectors show an abrupt pinch-out on the northern edge where a distinct moat is present, and a gradual tapering to the south. Internally we identify the base of the drift and four internal horizons, which we correlate throughout the drift. Two units display high amplitude reflectors, marked lensoidal character and restricted lateral extent, suggesting the occurrence of more energetic sedimentary conditions. Facies typical for contourite deposition are found in the sediment cores, with strongly bioturbated sediments and abundant silty/sandy mottles that contain shell fragments. These characteristics, along with the morphological and seismic information, suggest a strong control by a bottom current flowing along the moat on the northern edge of the

  7. Provenance of a prominent sediment drift on the northern slope of the South China Sea

    Institute of Scientific and Technical Information of China (English)

    SHAO; Lei

    2001-01-01

    [1]Sarnthein, M., Pflaumann, U., Wang, P. X. et al., Preliminary report on Sonne-95 cruise “Monitor Monsoon“ to the South China Sea, Reports, Geol.-Palaont. Inst. Univ. Kiel, 68, 1994, 125.[2]Wang, L., Sarnthein, M., High-reso1ution paleoceanographic records during the last 4000 years from the northern slope of the South China Sea, Quaternary Sciences, 1999, 1:27-31.[3]Wang, P.X., Prell, W. L., Blum, P. et al., Proceedings of the Ocean Drilling Program, Initial Reports South China Sea,Volume 184, College Station TX (Ocean Drilling Program), 2000, 18-20.[4]Shao, L., Dong, W., Liu, Z. et al., Trace elements analysis of sediments from the South China Sea, Journal of Tong ji Uni versity, 1999, 27(supp.): 55-60.[5]Taylor, S. R., McLennan, S. M., The Continental Crust: Its Composition and Evolution, in An Examination of the Geo chemical Record Preserved in Sedimentary Rocks, Oxford: Blackwell Scientific Publication, 1985, 1-301.[6]McLennan, S. M., Rare earth elements in sedimentary rocks, Influence of provenance and sedimentary processes, in Geo chemistry and Mineralogy of Rare Earth Elements (ed. Lipin, B. R. et al.), Washington: The Mineralogical Society of America, 1989, 169-200.[7]McLennan, S. M., Hemming, S., McDaniel, M. J. et al., Geochemical approaches to sedimentation, provenance and tec tonics, in Processes Controlling the Composition of Clastic Sediments (ed. Jonhanson, M. J. et al.), Boulder: Geological Society of America, Special Paper 284, 1993, 21-40.[8]Rollinson, H. R., Using Geochemical Data: Evaluation, Presentation, Interpretation, London: Longman Scientific, Tech nical, 1993, 352.[9]Cullers, R. L., Basu, A., Suttner, L. J., Geochemical signature of provenance in sand-mixed material in soils and stream sediments near the Tobacco Root batholith, Montana, USA, Chem. Geol., 1988, 70: 335-348.[10]Bhatia, M. R., Crook, K. A. W., Trace element characteristics of graywackes and tectonic setting discrimination of

  8. Feeding habit of juvenile fishes associated with drifting seaweeds in the East China Sea with reference to oceanographic parameters

    OpenAIRE

    Hasegawa, Takamasa; Manda, Atsuyoshi; Takatsuki, Naoki; KAWABATA, YUUKI; NISHIHARA Gregory N.; Fujita, Shinji; Kawabe, Ryo; Yamada, Misato; Kinoshita, Tsukasa; Yamawaki, Nobuhiro; Morii, Yasuhiro; Sakakura, Yoshitaka

    2016-01-01

    Many commercially important fishes associate with drifting seaweeds in their juvenile stage, however, the ecological significance of drifting seaweeds for juvenile fishes is still unclear. We postulated that the following two hypotheses may be applicable for juvenile fishes associate with drifting seaweeds, the “concentration of food supply” hypothesis: juvenile fishes are attracted by phytal animals on the drifting seaweeds and the “indicator-log” hypothesis: fish use accumulations of drifti...

  9. Square-wave anodic-stripping voltammetric determination of Cd, Pb, and Cu in a hydrofluoric acid solution of siliceous spicules of marine sponges (from the Ligurian Sea, Italy, and the Ross Sea, Antarctica)

    Energy Technology Data Exchange (ETDEWEB)

    Truzzi, C.; Annibaldi, A.; Illuminati, S.; Bassotti, E.; Scarponi, G. [Polytechnic University of Marche, Ancona (Italy). Department of Marine Science

    2008-09-15

    Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead, and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution ({proportional_to}0.55 mol L{sup -1} HF, pH {proportional_to}1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc support was used. The optimum experimental conditions, evaluated also in terms of the signal-to-noise ratio, were as follows: deposition potential -1100 mV vs. Ag/AgCl, KCl 3 mol L{sup -1}, deposition time 3-10 min, electrode rotation 3000 rpm, SW scan from -1100 mV to +100 mV, SW pulse amplitude 25 mV, frequency 100 Hz, {delta}E{sub step} 8 mV, t{sub step} 100 ms, t{sub wait} 60 ms, t{sub delay} 2 ms, t{sub meas} 3 ms. Under these conditions the metal peak potentials were Cd -654{+-}1 mV, Pb -458 {+-} 1 mV, Cu -198{+-}1 mV. The electrochemical behaviour was reversible for Pb, quasi-reversible for Cd, and kinetically controlled (possibly following chemical reaction) for Cu. The linearity of the response with concentration was verified up to {proportional_to}4 {mu}g L{sup -1} for Cd and Pb and {proportional_to}20 {mu}g L{sup -1} for Cu. The detection limits were 5.8 ng L{sup -1}, 3.6 ng L{sup -1}, and 4.3 ng L{sup -1} for Cd, Pb, and Cu, respectively, with t{sub d}=5 min. The method was applied for determination of the metals in spicules of two specimens of marine sponges (Demosponges) from the Portofino natural reserve (Ligurian Sea, Italy, Petrosia ficiformis) and Terra Nova Bay (Ross Sea, Antarctica, Sphaerotylus antarcticus). The metal contents varied from tens of ng g{sup -1} to {proportional_to}1 {mu}g g{sup -1}, depending on the metal considered and with significant differences between the two sponge species. (orig.)

  10. Coupling survey data with drift model results suggests that local spawning is important for Calanus finmarchicus production in the Barents Sea

    Science.gov (United States)

    Kvile, Kristina Øie; Fiksen, Øyvind; Prokopchuk, Irina; Opdal, Anders Frugård

    2017-01-01

    The copepod Calanus finmarchicus is an important part of the diet for several large fish stocks feeding in the Atlantic waters of the Barents Sea. Determining the origin of the new generation copepodites present on the Barents Sea shelf in spring can shed light on the importance of local versus imported production of C. finmarchicus biomass in this region. In this study, we couple large-scale spatiotemporal survey data (> 30 years in both Norwegian Sea and Barents Sea areas) with drift trajectories from a hydrodynamic model to back-calculate and map the spatial distribution of C. finmarchicus from copepod to egg, allowing us to identify potential adult spawning areas. Assuming the adult stage emerges from overwintering in the Norwegian Sea, our results suggest that copepodites sampled at the Barents Sea entrance are a mix of locally spawned individuals and long-distance-travellers advected northwards along the Norwegian shelf edge. However, copepodites sampled farther east in the Barents Sea (33°30‧E) are most likely spawned on the Barents Sea shelf, potentially from females that have overwintered locally. Our results support that C. finmarchicus dynamics in the Barents Sea are not, at least in the short-term, solely driven by advection from the Norwegian Sea, but that local production may be more important than commonly believed.

  11. Drifting buoy and other data from the Beaufort Sea as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 05 November 1975 to 01 October 1976 (NODC Accession 7700019)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy and other data was collected from the Beaufort Sea by the University of Washington (UW) as part of the Outer Continental Shelf Environmental Assessment...

  12. Drifting buoy and other data from the Arctic Ocean and Beaufort Sea as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 04 November 1975 to 01 October 1976 (NODC Accession 7700114)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from the Arctic Ocean and Beaufort Sea by the University of Washington (UW) as part of the Outer Continental Shelf Environmental...

  13. Drifting buoy and other data from the Beaufort Sea and other locations as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 03 March 1977 to 05 April 1977 (NODC Accession 7700543)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from the Beaufort Sea and other locations by the University of Washington (UW) as part of the Outer Continental Shelf Environmental...

  14. Drifting buoy and other data from the Beaufort Sea and other locations as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 04 April 1977 to 03 July 1977 (NODC Accession 7700780)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from the Beaufort Sea by the University of Washington (UW) as part of the Outer Continental Shelf Environmental Assessment Program...

  15. Drifting buoy and other data from the Chukchi Sea as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 27 June 1977 to 07 November 1977 (NODC Accession 7800005)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from the Chukchi Sea by the University of Washington (UW) as part of the Outer Continental Shelf Environmental Assessment Program...

  16. Upper ocean currents and sea surface temperatures (SST) from Satellite-tracked drifting buoys (drifters) as part of the Global Drifter Program for Hawaii region 1980/02/01 - 2009/03/31 (NODC Accession 0063296)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite-tracked drifting buoys ("drifters") collect measurements of upper ocean currents and sea surface temperatures (SST) around the world as part of the Global...

  17. Drifting buoy and other data from the Bering Sea as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 27 May 1977 to 07 January 1978 (NODC Accession 7800692)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data was collected from the Bering Sea by the Atlantic Oceanographic and Meteorological Laboratory (AOML) as part of the Outer Continental Shelf...

  18. The ROSS Language Manual.

    Science.gov (United States)

    1982-09-01

    when receiving (Mary requests meeting) (tell Mary meet for lunch at Superfood ) (tell Eunice bring stock reports) (tell Secretary cancel other lunch...someone requests meeting) (if (equal ’stockbroker (ask !someone recall your occupation)) then (tell ?someone meet for lunch at Superfood ) (tell...meet for lunch at Superfood ). Several other prefixes commonly used when writing ROSS code, either to control evaluation or to dictate variables in

  19. OBLIQUE TOWING TEST AND MANEUVER SIMULATION AT LOW SPEED AND LARGE DRIFT ANGLE FOR DEEP SEA OPEN-FRAMED REMOTELY OPERATED VEHICLE

    Institute of Scientific and Technical Information of China (English)

    FAN Shi-bo; LIAN Lian; REN Ping; HUANG Guo-liang

    2012-01-01

    This article presents the newly designed oblique towing test in the horizontal plane for the scaled model of 4 500 m deep sea open-framed Remotely Operated Vehicle (ROV),which is being researched and developed by Shanghai Jiao Toug University.Accurate hydrodynamics coefficients measurement is significant for the maneuverability and control system design.The scaled model of ROV was constructed by 1∶1.6.Hydrodynamics tests of large drift angle were conducted through Large Amplitude Horizontal Planar Motion Mechanism (LAHPMM) under low speed.Multiple regression method is adopted to process the test data and obtain the related hydrodynamic coefficients.Simulations were designed for the horizontal plane motion of large drift angle to verify the coefficients calculated.And the results show that the data can satisfy with the design requirements of the ROV developed.

  20. Bandura, Ross, and Ross: Observational Learning and the Bobo Doll

    Science.gov (United States)

    Artino, Anthony R., Jr.

    2007-01-01

    Since the publication of their seminal article entitled, "Transmission of Aggression Through Imitation of Aggressive Models" (Bandura, Ross, & Ross, 1961), the work of Albert Bandura and his co-authors has had an immeasurable impact on the field of psychology, in general, and educational psychology, more specifically. The purpose of this report is…

  1. 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.

  2. Inter-annual and inter-specific differences in the drift of fish eggs and yolksac larvae in the North Sea: A biophysical modeling approach

    Directory of Open Access Journals (Sweden)

    Myron A. Peck

    2009-10-01

    Full Text Available We employed 3-D biophysical modeling and dispersion kernel analysis to explore inter-annual and inter-specific differences in the drift trajectories of eggs and yolksac larvae of plaice (Pleuronectes platessa, Atlantic cod (Gadus morhua, sprat (Sprattus sprattus and horse mackerel (Trachurus trachurus in the North Sea. In this region, these four species exhibit peak spawning during the boreal winter, late winter/early spring, late spring/early summer, and mid-summer respectively, but utilize the same spawning locations (our simulations included Dogger Bank, Southern Bight and the German Bight. Inter-annual differences in the temperature history, and an increase in the area of dispersion and final distribution at the end of the yolksac phase were more pronounced (and related to the North Atlantic Oscillation for winter- and early spring-spawners compared to late spring/summer spawners. The progeny of the latter experienced the largest (up to 10-fold inter-annual differences in drift distances, although absolute drift distances were modest (~2 to 30 km when compared to those of the former (~ 20 to 130 km. Our results highlight the complex interplay that exists between the specific life history strategies of the different species and the impacts of the variability in (climate-driven physical factors during the earliest life stages of marine fish.

  3. Long-distance dispersal by sea-drifted seeds has maintained the global distribution of Ipomoea pes-caprae subsp. brasiliensis (Convolvulaceae).

    Science.gov (United States)

    Miryeganeh, Matin; Takayama, Koji; Tateishi, Yoichi; Kajita, Tadashi

    2014-01-01

    Ipomoea pes-caprae (Convolvulaceae), a pantropical plant with sea-drifted seeds, is found globally in the littoral areas of tropical and subtropical regions. Unusual long-distance seed dispersal has been believed to be responsible for its extraordinarily wide distribution; however, the actual level of inter-population migration has never been studied. To clarify the level of migration among populations of I. pes-caprae across its range, we investigated nucleotide sequence variations by using seven low-copy nuclear markers and 272 samples collected from 34 populations that cover the range of the species. We applied coalescent-based approaches using Bayesian and maximum likelihood methods to assess migration rates, direction of migration, and genetic diversity among five regional populations. Our results showed a high number of migrants among the regional populations of I. pes-caprae subsp. brasiliensis, which suggests that migration among distant populations was maintained by long-distance seed dispersal across its global range. These results also provide strong evidence for recent trans-oceanic seed dispersal by ocean currents in all three oceanic regions. We also found migration crossing the American continents. Although this is an apparent land barrier for sea-dispersal, migration between populations of the East Pacific and West Atlantic regions was high, perhaps because of trans-isthmus migration via pollen dispersal. Therefore, the migration and gene flow among populations across the vast range of I. pes-caprae is maintained not only by seed dispersal by sea-drifted seeds, but also by pollen flow over the American continents. On the other hand, populations of subsp. pes-caprae that are restricted to only the northern part of the Indian Ocean region were highly differentiated from subsp. brasiliensis. Cryptic barriers that prevented migration by sea dispersal between the ranges of the two subspecies and/or historical differentiation that caused local adaptation

  4. Long-distance dispersal by sea-drifted seeds has maintained the global distribution of Ipomoea pes-caprae subsp. brasiliensis (Convolvulaceae.

    Directory of Open Access Journals (Sweden)

    Matin Miryeganeh

    Full Text Available Ipomoea pes-caprae (Convolvulaceae, a pantropical plant with sea-drifted seeds, is found globally in the littoral areas of tropical and subtropical regions. Unusual long-distance seed dispersal has been believed to be responsible for its extraordinarily wide distribution; however, the actual level of inter-population migration has never been studied. To clarify the level of migration among populations of I. pes-caprae across its range, we investigated nucleotide sequence variations by using seven low-copy nuclear markers and 272 samples collected from 34 populations that cover the range of the species. We applied coalescent-based approaches using Bayesian and maximum likelihood methods to assess migration rates, direction of migration, and genetic diversity among five regional populations. Our results showed a high number of migrants among the regional populations of I. pes-caprae subsp. brasiliensis, which suggests that migration among distant populations was maintained by long-distance seed dispersal across its global range. These results also provide strong evidence for recent trans-oceanic seed dispersal by ocean currents in all three oceanic regions. We also found migration crossing the American continents. Although this is an apparent land barrier for sea-dispersal, migration between populations of the East Pacific and West Atlantic regions was high, perhaps because of trans-isthmus migration via pollen dispersal. Therefore, the migration and gene flow among populations across the vast range of I. pes-caprae is maintained not only by seed dispersal by sea-drifted seeds, but also by pollen flow over the American continents. On the other hand, populations of subsp. pes-caprae that are restricted to only the northern part of the Indian Ocean region were highly differentiated from subsp. brasiliensis. Cryptic barriers that prevented migration by sea dispersal between the ranges of the two subspecies and/or historical differentiation that

  5. Changes in distribution patterns of 0-group bivalves in the Wadden Sea: Byssus-drifting releases juveniles from the constraints of hydrography

    Science.gov (United States)

    Armonies, W.

    1996-06-01

    grain size distribution and tidal level within the area studied. On a scale of hundreds of metres, there were no consistent correlations between juvenile abundance and sediment granulometry in any species. In summary, it seems that hydrography ruled the initial settlement of larvae to the sediment and strongly influenced the subsequent redistribution of juveniles caused by passive resuspension. The outcome of actively initiated migrations, on the other hand, was only weakly influenced by hydrography. Therefore it is suggested that hydrography plays a dominant role in the initial development of km-scale distributional patterns of just-settled bivalves in the Wadden Sea, while habitat selection is delayed to the byssus-drifting postlarvae phase.

  6. Testing the larval drift hypothesis in the Baltic Sea: retention versus dispersion caused by wind-driven circulation

    DEFF Research Database (Denmark)

    Hinrichsen, H.H.; St. John, Michael; Aro, E.;

    2001-01-01

    the west and south resulted in a rapid transport of larvae into shallow coastal regions. Based on the results obtained from these drift experiments and a wind data time series from the meteorological station Christiansoe a transport index has been developed, variations in annual retention/dispersal have...

  7. Short-term sea ice forecasting: An assessment of ice concentration and ice drift forecasts using the U.S. Navy's Arctic Cap Nowcast/Forecast System

    Science.gov (United States)

    Hebert, David A.; Allard, Richard A.; Metzger, E. Joseph; Posey, Pamela G.; Preller, Ruth H.; Wallcraft, Alan J.; Phelps, Michael W.; Smedstad, Ole Martin

    2015-12-01

    In this study the forecast skill of the U.S. Navy operational Arctic sea ice forecast system, the Arctic Cap Nowcast/Forecast System (ACNFS), is presented for the period February 2014 to June 2015. ACNFS is designed to provide short term, 1-7 day forecasts of Arctic sea ice and ocean conditions. Many quantities are forecast by ACNFS; the most commonly used include ice concentration, ice thickness, ice velocity, sea surface temperature, sea surface salinity, and sea surface velocities. Ice concentration forecast skill is compared to a persistent ice state and historical sea ice climatology. Skill scores are focused on areas where ice concentration changes by ±5% or more, and are therefore limited to primarily the marginal ice zone. We demonstrate that ACNFS forecasts are skilful compared to assuming a persistent ice state, especially beyond 24 h. ACNFS is also shown to be particularly skilful compared to a climatologic state for forecasts up to 102 h. Modeled ice drift velocity is compared to observed buoy data from the International Arctic Buoy Programme. A seasonal bias is shown where ACNFS is slower than IABP velocity in the summer months and faster in the winter months. In February 2015, ACNFS began to assimilate a blended ice concentration derived from Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Interactive Multisensor Snow and Ice Mapping System (IMS). Preliminary results show that assimilating AMSR2 blended with IMS improves the short-term forecast skill and ice edge location compared to the independently derived National Ice Center Ice Edge product.

  8. 北冰洋中心区海冰漂流与大气过程%Sea ice drifting and atmospheric processes over the central Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    卞林根; 王继志; 孙玉龙; 逯昌贵; 林祥; 李多

    2014-01-01

    利用北冰洋中心区漂流自动气象站(DAWS )2012年9月-2013年2月的观测数据,分析了北极点周围海冰漂流轨迹和速度及相关大气过程。结果显示,北冰洋中心区海冰具有不稳定漂流过程。2012年9月1日-2013年1月6日,DAWS 所在海冰从西向西北方向漂流,2013年1月6日以后稳定地向东南方向漂流,平均移速为0.06 m/s,最大达到0.4 m/s。海冰漂流方向的突变和加速与穿极气旋和急流的影响有关。净辐射常出现短期突变过程,导致海冰从大气吸收能量,减缓了海冰的辐射冷却。爆发性增温过程的最大幅度达到30℃,是由强穿极气旋和伴随的暖湿气流向北极中心区输送引起,这种现象在中低纬度十分罕见。增温过程的作用是高空大气向冰面输送热量,导致海冰破裂,海冰硬度的脆变,减缓海冰厚度的增长,这种过程可能是北极海冰面积和厚度减少重要过程。%Based on the data observed by drifting automatic weather station (DAWS )from August 2012 to February 2013 and NOAA re-analyzing data over the Arctic Centre,the track,movement velocity of drifting sea ice and the e-volution of temperature,humidity,radiation of drifting sea ice ,atmospheric processes,including the evolvement of flow pattern and temperature field and its relative dynamic and thermodynamic processes over the Arctic tropo-sphere in 500 and 1 000 hPa during period of autumn and winter around north polar are analyzed.The results show that,before 6 January 2013,sea ice moves mainly from the east to the northwest,and appearing the unstable trajec-tory of roundabout and turning process,then drifting towards to the south east.Its average drift velocity is 0.06 m/s,the maximum speed up to 0.4 m/s.The mutation and accelerated in the direction of polar sea ice drifting is associated with the activities of across the polar cyclone and jet stream in polar troposphere.Sea ice surface net ra

  9. An initial carbon export assessment in the Mediterranean Sea based on drifting sediment traps and the Underwater Vision Profiler data sets

    Science.gov (United States)

    Ramondenc, Simon; Madeleine, Goutx; Lombard, Fabien; Santinelli, Chiara; Stemmann, Lars; Gorsky, Gabriel; Guidi, Lionel

    2016-11-01

    During the SESAME EU FP6 project, all available particulate organic carbon (POC) data collected from drifting sediment trap and Underwater Vision Profiler deployments (INSU PROOF database, 1991-2011) were gathered in order to assess carbon export at the scale of the Mediterranean Sea. In this study, we observed that particle size, POC export, and the contribution of microphytoplankton to the phytoplankton community structure, all decreased following the west to east net primary production gradient. One the other hand, no clear longitudinal gradient was found regarding particle composition (C/N ratio or lipid content). The above longitudinal patterns were also observed at the seasonal scale from spring to summer in the northwestern sub-basin. These observations suggest that particle size rather than organic matter composition controls fluxes of POC in the Mediterranean Sea. The comparison between POC and dissolved organic carbon (DOC) fluxes highlights the different time-scale of physicals vertical mechanisms and suggests that DOC flux can play an underestimated role in the supply of fresh carbon to the deep waters Mediterranean Sea. Indeed, DOC supply to deeper layers can be one order of magnitude larger than particle carbon flux but occurs in pulses when stratification breaks due to (i) deep-water formation, or (ii) winter mixing. In contrast, the vertical export of POC occurs throughout the year bringing weak, but almost continuous, energy to meso- and bathypelagic organisms.

  10. Combined effects of hydrographic structure and iron and copper availability on the phytoplankton growth in Terra Nova Bay Polynya (Ross Sea, Antarctica)

    Science.gov (United States)

    Rivaro, Paola; Luisa Abelmoschi, Maria; Grotti, Marco; Ianni, Carmela; Magi, Emanuele; Margiotta, Francesca; Massolo, Serena; Saggiomo, Vincenzo

    2012-04-01

    Surface water (CLIMA) Project of the Programma Nazionale di Ricerca in Antartide activities. Dissolved oxygen, nutrients, phytoplankton pigments and concentration and complexation of dissolved trace metals were determined. Experimental data were elaborated by Principal Component Analysis (PCA). As a result of solar heating and freshwater inputs from melting sea-ice, the water column was strongly stratified with an Upper Mixed Layer 4-16 m deep. The integrated Chl a in the layer 0-100 m ranged from 60 mg m-2 to 235 mg m-2, with a mean value of 138 mg m-2. The pigment analysis showed that diatoms dominated the phytoplankton assemblage. Major nutrients were generally high, with the lowest concentration at the surface and they were never fully depleted. The Si:N drawdown ratio was close to the expected value of 1 for Fe-replete diatoms. We evaluated both the total and the labile dissolved fraction of Fe and Cu. The labile fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The total dissolved Fe ranged from 0.48 to 3.02 nM, while the total dissolved Cu from 3.68 to 6.84 nM. The dissolved labile Fe ranged from below the detection limit (0.15 nM) to 1.22 nM, and the dissolved labile Cu from 0.31 to 1.59 nM, respectively. The labile fractions measured at 20 m were significantly lower than values in 40-100 m samples. As two stations were re-sampled 5 days later, we evaluated the short-term variability of the physical and biogeochemical properties. In particular, in a re-sampled station at 20 m, the total dissolved Fe increased and the total dissolved Cu decreased, while their labile fraction was relatively steady. As a result of the increase in total Fe, the percentage of the labile Fe decreased. An increase of the Si:N, Si:P and Si:FUCO ratios was measured also in the re-sampled station. On this basis, we speculated that a switch from a Fe-replete to a Fe-deplete condition was occurring.

  11. Regional Changes in the Sea Ice Cover and Ice Production in the Antarctic

    Science.gov (United States)

    Comiso, Josefino C.

    2011-01-01

    Coastal polynyas around the Antarctic continent have been regarded as sea ice factories because of high ice production rates in these regions. The observation of a positive trend in the extent of Antarctic sea ice during the satellite era has been intriguing in light of the observed rapid decline of the ice extent in the Arctic. The results of analysis of the time series of passive microwave data indicate large regional variability with the trends being strongly positive in the Ross Sea, strongly negative in the Bellingshausen/Amundsen Seas and close to zero in the other regions. The atmospheric circulation in the Antarctic is controlled mainly by the Southern Annular Mode (SAM) and the marginal ice zone around the continent shows an alternating pattern of advance and retreat suggesting the presence of a propagating wave (called Antarctic Circumpolar Wave) around the circumpolar region. The results of analysis of the passive microwave data suggest that the positive trend in the Antarctic sea ice cover could be caused primarily by enhanced ice production in the Ross Sea that may be associated with more persistent and larger coastal polynyas in the region. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate-of-increase in the net ice export of about 30,000 km2 per year. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 km3/year, which is almost identical, within error bars, to our estimate of the trend in ice production. In addition to the possibility of changes in SAM, modeling studies have also indicated that the ozone hole may have a role in that it causes the deepening of the lows in the western Antarctic region thereby causing strong winds to occur offthe Ross-ice shelf.

  12. Verification of Geosat sea surface topography in the Gulf Stream extension with surface drifting buoys and hydrographic measurements

    Science.gov (United States)

    Willebrand, J.; KäSe, R. H.; Stammer, D.; Hinrichsen, H.-H.; Krauss, W.

    1990-03-01

    Altimeter data from Geosat have been analyzed in the Gulf Stream extension area. Horizontal maps of the sea surface height anomaly relative to an annual mean for various 17-day intervals were constructed using an objective mapping procedure. The mean sea level was approximated by the dynamic topography from climatological hydrographic data. Geostrophic surface velocities derived from the composite maps (mean plus anomaly) are significantly correlated with surface drifter velocities observed during an oceanographie experiment in the spring of 1987. The drifter velocities contain much energy on scales less than 100 km which are not resolved in the altimetric maps. It is shown that the composite sea surface height also agrees well with ground verification from hydrographic data along sections in a triangle between the Azores, Newfoundland, and Bermuda, except in regions of high mean gradients.

  13. Exposure to a putative alarm cue reduces downstream drift in larval sea lamprey Petromyzon marinus in the laboratory.

    Science.gov (United States)

    Wagner, C M; Kierczynski, K E; Hume, J B; Luhring, T M

    2016-09-01

    An experimental mesocosm study suggested larval sea lamprey Petromyzon marinus detect and respond to an alarm cue released by dead adult conspecifics. Larvae exhibited a reduced tendency to move downstream when exposed to the cue and were less likely to move under continuous v. pulsed exposure. These findings support the hypothesis that short-term exposure to the alarm cue would probably result in retraction into the burrow, consistent with the blind, cryptic lifestyle of the larval P. marinus.

  14. Estimation of annual heat flux balance at the sea surface from sst (NOAA-satellite and ships drift data off southeast Brazil

    Directory of Open Access Journals (Sweden)

    Yoshimine Ikeda

    1985-01-01

    Full Text Available The objective of this work is to study the possibility of estimating the heat flux balance at the sea surface from GOSSTCOMP (Global Ocean Sea Surface Temperature Computation developed by NOAA/NESS, USA, and sea surface current data based from ships drift information obtained from Pilot Charts, published by the Diretoria de Hidrografia e Navegação (DHN, Brazilian Navy. The annual mean value of the heat flux balance at the sea surface off southeast Brazil for 1977, is estimated from data on the balance between the heat transported by the currents and that transported by eddy diffusion for each volume defined as 2º x 2º (Lat. x Long. square with a constant depth equivalent to an oceanic mixed layer, 100 m thick. Results show several oceanic areas where there are net flows of heat from atmosphere towards the sea surface. In front of Rio de Janeiro the heat flow was downward and up to 70 ly day-1 and is probably related to the upwellirug phenomenon normally occurring in that area. Another coastal area between Lat. 25ºS to 28ºS indicated an downward flow up to 50 ly day-1; and for an area south of Lat. 27ºS, Long. 040ºW - 048ºW an downward flow up to 200 ly day-1, where the transfer was probably due to the cold water of a nortward flux from the Falkland (Malvinas Current. Results also show several oceanic areas where net flows of heat (of about -100 ly day-1 were toward the atmosphere. In the oceanic areas Lat. 19ºS - 23ºS and Lat. 24ºS - 30ºS, the flows were probably due to the warm water of a southward flux of the Brazil Current. The resulting fluxes from the warm waters of the Brazil Current when compared with those from warm waters of the Gulf Stream and Kuroshio, indicate that the Gulf Stream carries about 3.3 times and the Kuroshio 1.7 times more heat than the Brazil Current. These values agree with those of data available on the heat fluxes of the above mentioned Currents calculated by different methods (Budyko, 1974.

  15. Operation of a Hovercraft Scientific Platform Over Sea Ice in the Arctic Ocean Transpolar Drift (81 - 85N): The FRAM-2012 Experience

    Science.gov (United States)

    Hall, J. K.; Kristoffersen, Y.

    2013-12-01

    We have tested the feasibility of hovercraft travel through predominantly first year ice of the Transpolar Drift between 81°N - 85°N north of Svalbard. With 2-9 ridges per kilometer, our hovercraft (Griffon TD2000 Mark II), with an effective hover height of about 0.5 m, had to travel a distance 1.3 times the great circle distance between the point of origin and the final destination. Instantaneous speeds were mostly 5-7 knots. Two weeks later icebreaker Oden completed the same transit under conditions with no significant pressure in the ice at a speed mostly 1 knot higher than the hovercraft and travelled 1.2 times the great circle distance. The hovercraft spent 25 days monitoring micro-earthquake activity of the Arctic Mid-Ocean Ridge at a section of the spreading center where no seismicity has been recorded by the global seismograph network. More than ten small earthquake events per day were recorded. Visibility appears to be the most critical factor to hovercraft travel in polar pack ice. Improved control of hovercraft motion would substantially increase the potential usefulness of hovercraft in the sea ice environment. University of Bergen graduate student Gaute Hope emplacing one of the hydrophones in the triangular array used to locate small earthquakes over the Gakkel Ridge rift valley around 85N during FRAM-2012. The research hovercraft R/H SABVABAA is in the background.

  16. Earth - Ross Ice Shelf, Antarctica

    Science.gov (United States)

    1991-01-01

    This color picture of Antarctica is one part of a mosaic of pictures covering the entire Antarctic continent taken during the hours following Galileo's historic first encounter with its home planet. The view shows the Ross Ice Shelf. An occasional mountain can be seen poking through the ice. It is late spring in Antarctica, so the sun never sets on the frigid, icy continent. This picture was taken on December 8, 1990.

  17. Short-term changes in particulate fluxes measured by drifting sediment traps during end summer oligotrophic regime in the NW Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    J. C. Marty

    2009-05-01

    Full Text Available Short-term changes in the flux of particulate matter were determined in the central north western Mediterranean Sea (near DYFAMED site using drifting sediment traps at 200 m depth in the course of the DYNAPROC 2 cruise (14 September–17 October 2004. In this period of marked water column stratification, POC fluxes varied by an order of magnitude, in the range of 0.03–0.29 mgC m−2 h−1 over the month and showed very rapid and high variations. Particulate carbon export represented less than 5% of integrated primary production, suggesting that phytoplankton production was essentially sustained by internal recycling of organic matter and retained within the photic zone. While PON and POP fluxes paralleled one another, the elemental ratios POC/PON and POC/POP, varied widely over short-term periods. Values of these ratios generally higher than the conventional Redfield ratio, together with the very low chlorophyll a flux recorded in the traps (mean 0.017 μg m−2 h−1, and the high phaeopigment and acyl lipid hydrolysis metabolite concentrations of the settling material, indicated that the organic matter reaching 200 m depth was reworked (by grazing, fecal pellets production, degradation and that algal sinking, dominated by nano- and picoplankton, made a small contribution to the downward flux. Over time, the relative abundance of individual lipid classes in organic matter (OM changed from glycolipids-dominated to neutral (wax esters, triacylglycerols and phospholipids-dominated, suggesting ecosystem maturation as well as rapid and continual exchanges between dissolved, suspended and sinking pools. Our most striking result was documenting the rapid change in fluxes of the various measured parameters. In the situation encountered here, with dominant regenerated production, a decrease of fluxes was noticed during windy periods (possibly through reduction of grazing. But fluxes increased as soon as calm

  18. 3-dimensional Oil Drift Simulations

    Science.gov (United States)

    Wettre, C.; Reistad, M.; Hjøllo, B.Å.

    Simulation of oil drift has been an ongoing activity at the Norwegian Meteorological Institute since the 1970's. The Marine Forecasting Centre provides a 24-hour service for the Norwegian Pollution Control Authority and the oil companies operating in the Norwegian sector. The response time is 30 minutes. From 2002 the service is extended to simulation of oil drift from oil spills in deep water, using the DeepBlow model developed by SINTEF Applied Chemistry. The oil drift model can be applied both for instantaneous and continuous releases. The changes in the mass of oil and emulsion as a result of evaporation and emulsion are computed. For oil spill at deep water, hydrate formation and gas dissolution are taken into account. The properties of the oil depend on the oil type, and in the present version 64 different types of oil can be simulated. For accurate oil drift simulations it is important to have the best possible data on the atmospheric and oceanic conditions. The oil drift simulations at the Norwegian Meteorological Institute are always based on the most updated data from numerical models of the atmosphere and the ocean. The drift of the surface oil is computed from the vectorial sum of the surface current from the ocean model and the wave induced Stokes drift computed from wave energy spectra from the wave prediction model. In the new model the current distribution with depth is taken into account when calculating the drift of the dispersed oil droplets. Salinity and temperature profiles from the ocean model are needed in the DeepBlow model. The result of the oil drift simulations can be plotted on sea charts used for navigation, either as trajectory plots or particle plots showing the situation at a given time. The results can also be sent as data files to be included in the user's own GIS system.

  19. Ross Ice Shelf Seismic Survey and Future Drilling Recommendation

    Science.gov (United States)

    van Haastrecht, Laurine; Ohneiser, Christian; Gorman, Andrew; Hulbe, Christina

    2016-04-01

    The Ross Ice Shelf (RIS) is one of three gateways through which change in the ocean can be propagated into the interior of West Antarctica. Both the geologic record and ice sheet models indicate that it has experienced widespread retreat under past warm climates. But inland of the continental shelf, there are limited data available to validate the models. Understanding what controls the rate at which the ice shelf will respond to future climate change is central to making useful climate projections. Determining the retreat rate at the end of the last glacial maximum is one part of this challenge. In November 2015, four lines of multi-channel seismic data, totalling over 45 km, were collected on the Ross Ice Shelf, approximately 300 km south of Ross Island using a thumper seismic source and a 96 channel snow streamer. The seismic survey was undertaken under the New Zealand Antarctic Research Institute (NZARI) funded Aotearoa New Zealand Ross Ice Shelf Programme to resolve bathymetric details and to image sea floor sediments under a proposed drilling site on the ice shelf, at about 80.7 S and 174 E. The thumper, a purpose-built, trailer mounted, weight-drop seismic source was towed behind a Hägglund tracked vehicle to image the bathymetry and sediments underneath the RIS. Seismic data collection on an ice shelf has unique challenges, in particular strong attenuation of the seismic energy by snow and firn, and complex multiple ray paths. The thumper, which consists of a heavy weight (250kg) that is dropped on a large, ski mounted steel plate, produced a consistent, repeatable higher energy signal when compared to sledge hammer source and allowed for a greater geographic coverage and lower environmental impact than an explosive source survey. Our survey revealed that the seafloor is smooth and that there may be up to 100 m of layered sediments beneath the seafloor and possibly deeper, more complex structures. A multiple generated by internally reflected seismic energy

  20. Bathymetry--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetry and shaded-relief maps of the Offshore of Fort Ross map area, California. Raster data file is included in...

  1. Contours--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetric contours for several seafloor maps of the Offshore of Fort Ross map area, California. The vector data file is...

  2. Sir Donald Ross, pioneer aortic valve surgeon.

    Science.gov (United States)

    Wheatley, David

    2015-06-01

    Tribute to Sir Donald Ross by David Wheatley, as read by Robert Kleinloog, President, Society of Cardiothoracic Surgeons of South Africa at the Annual Congress of the South African Heart Association 19 October 2014.

  3. Bathymetry--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetry and shaded-relief maps of the Offshore of Fort Ross map area, California. Raster data file is included in...

  4. Habitat--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the habitat map of the seafloor of the Offshore of Fort Ross map area, California. The polygon shapefile is included in...

  5. Contours--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetric contours for several seafloor maps of the Offshore of Fort Ross map area, California. The vector data file is...

  6. Widespread collapse of the Ross Ice Shelf during the late Holocene.

    Science.gov (United States)

    Yokoyama, Yusuke; Anderson, John B; Yamane, Masako; Simkins, Lauren M; Miyairi, Yosuke; Yamazaki, Takahiro; Koizumi, Mamito; Suga, Hisami; Kusahara, Kazuya; Prothro, Lindsay; Hasumi, Hiroyasu; Southon, John R; Ohkouchi, Naohiko

    2016-03-01

    The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (-560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km. Runaway grounding line conditions culminated once the ice became pinned on shallow banks in the western Ross Sea. This early episode of ice-shelf collapse is not observed in the eastern Ross Sea, where more episodic grounding line retreat took place. More widespread (∼280,000 km(2)) retreat of the ancestral Ross Ice Shelf occurred during the late Holocene. This event is recorded in sediment cores by a shift from terrigenous glacimarine mud to diatomaceous open-marine sediment as well as an increase in radiogenic beryllium ((10)Be) concentrations. The timing of ice-shelf breakup is constrained by compound specific radiocarbon ages, the first application of this technique systematically applied to Antarctic marine sediments. Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf.

  7. WATER TEMPERATURE and Other Data from DRIFTING PLATFORM From Chukchi Sea - NW Coast of Alaska from 19811219 to 19820101 (NODC Accession 8500079)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data were collected by Flow Industries, Inc. under contract number 03-78-B01-61 to NOAA . The data are primarily from drifting ice buoys and were collected in...

  8. Third Field Test of Satellite-Tracked Surface Drifting Buoys for Simulating the Movement of Spilled Oil on the Sea Surface. Cruise Report

    Energy Technology Data Exchange (ETDEWEB)

    Reed, M.

    1995-12-18

    This report describes experiments with drifting buoys as potential simulators of drifting oil spills. Two drifter types were deployed to test how well they could follow oil slicks. One was a sphere of diameter 30 cm, the other was a flattened spheroid of 37 cm horizontal diameter and 20 cm vertical diameter. Both were equipped with ARGOS transmitters, and were ballasted to float at their equators. A third type, the CODE drifter, was deployed to track the motion of water in the top meter of the water column. The CODE drifters consisted of a central vertical cylinder one meter long, four inch diameter, with four vertical sails radiating at right angles to the central shaft. The spheres and the spheroids followed the surface oil movement very well. The movement of the thick portion of the drifting oil should therefore be very well represented by the mean ARGOS trajectories. The CODE drifters proved very useful as markers for the dispersed and dissolved hydrocarbon cloud, and should become a standard part of the sampling procedures. The drifters would be much more useful in real-time spill situations if they could use GPS-VHF for real-time mapping. The track evaluations were done by the U.S. Minerals Management Service. 13 refs., 2 figs., 1 table

  9. Competing connections between the Ross Ice Shelf with the Southern Ocean.

    Science.gov (United States)

    Jendersie, Stefan

    2016-04-01

    The stability of the Ross Ice Shelf (RIS) is critical to both the East Antarctic Ice Sheet, and the West Antarctic Ice Sheet. Results from a climatological ice shelf-ocean coupled numerical model (ROMS) suggest a new circulation mechanism associated with High Salinity Water (HSSW) production in the Ross Sea Polynya (RSP) that controls oceanic heat access to the RIS cavity. Within the RSP the dense water-saturated water column contracts during winter and causes a seasonal drop in Sea Surface Height (SSH) localised to a convection chimney under the RSP. The SSH gradients of up to 1.5 mm per km are sufficient to generate a barotropic pressure gradient that can counteract the wide scale horizontal baroclinic force and reverse the geostrophic circulation. In water depths between 600 and 800 m north of the western RIS the effect causes the seasonal occurrence of a cyclonic circulation cell with transports greater than 1Sv. Appearing with the beginning of winter sea ice formation in the RSP it significantly changes the dynamics at the ice shelf front. The new mechanism is described as one element in a framework of oceanographic processes that mitigate the exchange between the deep ocean and the ocean cavity under the RIS. Our study links local circulation features that are known from observation and previous model studies, and for the first time establishes a coherent system of responsible physical forcing processes in the Ross Sea.​

  10. STS-110 Crew Interview: Jerry Ross

    Science.gov (United States)

    2002-01-01

    STS-110 Mission Specialist Jerry Ross is seen during this preflight interview, where he gives a quick overview of the mission before answering questions about his inspiration to become an astronaut and his career path. Ross outlines his role in the mission in general, and specifically during the docking and extravehicular activities (EVAs). He describes the payload (S0 Truss and Mobile Transporter) and the dry run installation of the S0 truss that will take place the day before the EVA for the actual installation. Ross discusses the planned EVAs in detail and outlines what supplies will be left for the resident crew of the International Space Station (ISS). He ends with his thoughts on the most valuable aspect of the ISS.

  11. Seafloor character--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents the seafloor-character map Offshore of Fort Ross, California (raster data file is included in "SeafloorCharacter_OffshoreFortRoss.zip,"...

  12. Seafloor character--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents the seafloor-character map Offshore of Fort Ross, California (raster data file is included in "SeafloorCharacter_OffshoreFortRoss.zip,"...

  13. Does the geoid drift west?

    Science.gov (United States)

    Backus, G. E.; Parker, R. L.; Zumberge, M. A.

    1985-01-01

    In 1970 Hide and Malin noted a correlation of about 0.8 between the geoid and the geomagnetic potential at the Earth's surface when the latter is rotated eastward in longitude by about 160 degrees and the spherical harmonic expansions of both functions are truncated at degree 4. From a century of magnetic observatory data, Hide and Malin inferred an average magnetic westward drift rate of about 0.27 degrees/year. They attributed the magnetic-gravitational correlation to a core event at about 1350 A.D. which impressed the mantle's gravity pattern at long wavelengths onto the core motion and the resulting magnetic field. The impressed pattern was then carried westward 160 degrees by the nsuing magnetic westward drift. An alternative possibility is some sort of steady physical coupling between the magnetic and gravitational fields (perhaps migration of Hide's bumps on the core-mantle interface). This model predicts that the geoid will drift west at the magnetic rate. On a rigid earth, the resulting changes in sea level would be easily observed, but they could be masked by adjustment of the mantle if it has a shell with viscosity considerably less than 10 to the 21 poise. However, steady westward drift of the geoid also predicts secular changes in g, the local acceleration of gravity, at land stations. These changes are now ruled out by recent independent high-accuracy absolute measurements of g made by several workers at various locations in the Northern Hemisphere.

  14. Holocene glacier dynamics on James Ross Island, NE Antarctic Peninsula

    Science.gov (United States)

    Davies, B. J.; Glasser, N. F.; Hambrey, M.

    2013-12-01

    The northern Antarctic Peninsula is currently warming very rapidly, which has resulted in ice sheet thinning, ice-shelf collapse, and rapid and widespread glacier recession. These small mountain glaciers are predicted to make a large sea level contribution over the coming century. Reconstructing past rates, volumes and magnitudes of change, particularly with respect to the former configuration of former ice sheets and ice shelves, is vital to contextualise contemporary change and to improve predictions of future ice-sheet behaviour. The aim of this research is therefore to investigate the relationship of deglacial ice sheet thinning and Holocene glacier fluctuations around James Ross Island, northeast Antarctic Peninsula, with temperature changes recorded in the Mount Haddington Ice Core. We use a combination of geomorphological mapping, from field campaigns and remotely sensed images, cosmogenic nuclide ages on glacially transported boulders, and numerical modelling with a simple 1D flowline model. Prior to 18 ka, James Ross Island was inundated by a thick and mainly cold-based ice sheet, which scattered granite erratics across the island. Ice sheet thickness and the rate of thinning is constrained by granite erratics on Terrapin Hill (610 m a.s.l.), and from flat-topped mesas at 370 m a.s.l. on Ulu Peninsula. During deglaciation and a period of rapid warming and eustatic sea level rise, the area was drained by Prince Gustav Ice Stream. The ice sheet reached its current configuration by around 6 ka, with glacier readvances around 4-5 ka. At Boulder Valley, near Terrapin Hill on James Ross Island, a large glacial readvance reached the current shoreline. It pre-dated the Mid-Holocene sea level high-stand, and has shorelines imprinted upon its seaward face. After 5.3 cal. ka BP and post-dating the mid-Holocene sea level high-stand, there was a readvance of at least 7 km by glacier 'IJR-45' on Ulu Peninsula. Rapid glacier recession occurred during a period of

  15. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Ross Lake National Recreation... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... snowmobiles the following locations within the Ross Lake National Recreation Area: (1) State Highway 20,...

  16. Coastal-change and glaciological map of the Ross Island area, Antarctica

    Science.gov (United States)

    Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S.

    2010-01-01

    Reduction in the area and volume of Earth?s two polar ice sheets is intricately linked to changes in global climate and to the resulting rise in sea level. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council. On the basis of these recommendations, the U.S. Geological Survey used its archive of satellite images to document changes in the cryospheric coastline of Antarctica and analyze the glaciological features of the coastal regions. The Ross Island area map is bounded by long 141? E. and 175? E. and by lat 76? S. and 81? S. The map covers the part of southern Victoria Land that includes the northwestern Ross Ice Shelf, the McMurdo Ice Shelf, part of the polar plateau and Transantarctic Mountains, the McMurdo Dry Valleys, northernmost Shackleton Coast, Hillary Coast, the southern part of Scott Coast, and Ross Island. Little noticeable change has occurred in the ice fronts on the map, so the focus is on glaciological features. In the western part of the map area, the polar plateau of East Antarctica, once thought to be a featureless region, has subtle wavelike surface forms (megadunes) and flow traces of glaciers that originate far inland and extend to the coast or into the Ross Ice Shelf. There are numerous outlet glaciers. Glaciers drain into the McMurdo Dry Valleys, through the Transantarctic Mountains into the Ross Sea, or into the Ross Ice Shelf. Byrd Glacier is the largest. West of the Transantarctic Mountains are areas of blue ice, readily identifiable on Landsat images, that have been determined to be prime areas for finding meteorites. Three subglacial lakes have been identified in the map area. Because McMurdo Station, the main U.S. scientific research station in Antarctica, is located on Ross Island in the map area, many of these and other features in the area have been studied extensively. The paper version of this map is

  17. Modelling sea ice formation in the Terra Nova Bay polynya

    Science.gov (United States)

    Sansiviero, M.; Morales Maqueda, M. Á.; Fusco, G.; Aulicino, G.; Flocco, D.; Budillon, G.

    2017-02-01

    Antarctic sea ice is constantly exported from the shore by strong near surface winds that open leads and large polynyas in the pack ice. The latter, known as wind-driven polynyas, are responsible for significant water mass modification due to the high salt flux into the ocean associated with enhanced ice growth. In this article, we focus on the wind-driven Terra Nova Bay (TNB) polynya, in the western Ross Sea. Brine rejected during sea ice formation processes that occur in the TNB polynya densifies the water column leading to the formation of the most characteristic water mass of the Ross Sea, the High Salinity Shelf Water (HSSW). This water mass, in turn, takes part in the formation of Antarctic Bottom Water (AABW), the densest water mass of the world ocean, which plays a major role in the global meridional overturning circulation, thus affecting the global climate system. A simple coupled sea ice-ocean model has been developed to simulate the seasonal cycle of sea ice formation and export within a polynya. The sea ice model accounts for both thermal and mechanical ice processes. The oceanic circulation is described by a one-and-a-half layer, reduced gravity model. The domain resolution is 1 km × 1 km, which is sufficient to represent the salient features of the coastline geometry, notably the Drygalski Ice Tongue. The model is forced by a combination of Era Interim reanalysis and in-situ data from automatic weather stations, and also by a climatological oceanic dataset developed from in situ hydrographic observations. The sensitivity of the polynya to the atmospheric forcing is well reproduced by the model when atmospheric in situ measurements are combined with reanalysis data. Merging the two datasets allows us to capture in detail the strength and the spatial distribution of the katabatic winds that often drive the opening of the polynya. The model resolves fairly accurately the sea ice drift and sea ice production rates in the TNB polynya, leading to

  18. STS-88 Crew Interview: Jerry Ross

    Science.gov (United States)

    1998-01-01

    Jerry Ross discusses the seven-day mission that will be highlighted by the mating of the U.S.-built Node 1 station element to the Functional Energy Block (FGB) which will already be in orbit, and two spacewalks to connect power and data transmission cables between the Node and the FGB. Node 1 will be the first Space Station hardware delivered by the Space Shuttle. He also disscusses the assembly sequence. The crew will conduct a series of rendezvous maneuvers similar to those conducted on other Shuttle missions to reach the orbiting FGB. Once the two elements are docked, Ross and Newman will conduct two scheduled spacewalks to connect power and data cables between the Node, PMAs and the FGB. The day following the spacewalks, Endeavour will undock from the two components, completing the first Space Station assembly mission.

  19. Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

    Science.gov (United States)

    Brunt, Kelly M.; MacAyeal, Douglas R.

    2014-01-01

    Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

  20. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E. Gaffiney

    2004-11-23

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

  1. Deux lectures critiques d'Alf Ross

    OpenAIRE

    Millard, Eric

    2000-01-01

    Suivi de deux textes de Kelsen (Une théorie réaliste et la Théorie pure du droit ; notice HAL : http://halshs.archives-ouvertes.fr/halshs-00126308) et Hart (Sur le réalisme scandinave ; notice HAL : http://halshs.archives-ouvertes.fr/halshs-00126310); Présentation de deux textes d'Hans Kelsen et d'HLA Hart critiquant l'ouvrage On law and Justice de Ross

  2. Modeling concept drift

    DEFF Research Database (Denmark)

    Borchani, Hanen; Martinez, Ana Maria; Masegosa, Andrés R.

    2015-01-01

    An often used approach for detecting and adapting to concept drift when doing classification is to treat the data as i.i.d. and use changes in classification accuracy as an indication of concept drift. In this paper, we take a different perspective and propose a framework, based on probabilistic ...

  3. Abstraction of Drift Seepage

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Birkholzer

    2004-11-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package

  4. Ross to the Rescue! Rutgers' Ross Todd's Quest to Renew School Libraries

    Science.gov (United States)

    Kenney, Brian

    2006-01-01

    This article presents an interview with Ross Todd, director of research at Rutgers University's Center for International Scholarship in School Libraries. Todd talks about the impact of the Ohio study, based on student's evaluation of their media centers, and his quest to renew school libraries. He stresses that part of the renewal and continuous…

  5. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  6. Drift in Diffusion Gradients

    Directory of Open Access Journals (Sweden)

    Fabio Marchesoni

    2013-08-01

    Full Text Available The longstanding problem of Brownian transport in a heterogeneous quasi one-dimensional medium with space-dependent self-diffusion coefficient is addressed in the overdamped (zero mass limit. A satisfactory mesoscopic description is obtained in the Langevin equation formalism by introducing an appropriate drift term, which depends on the system macroscopic observables, namely the diffuser concentration and current. The drift term is related to the microscopic properties of the medium. The paradoxical existence of a finite drift at zero current suggests the possibility of designing a Maxwell demon operating between two equilibrium reservoirs at the same temperature.

  7. Elisabeth Kubler-Ross as a Religious Leader.

    Science.gov (United States)

    Klass, Dennis; Hutch, Richard A.

    1986-01-01

    Considers Elisabeth Kubler-Ross as a charismatic religious leader and examines the feminine quality of her message and leadership style. An examination of the prospects for an enduring cultural innovation based on Kubler-Ross's work concludes that her leadership does not conform to conditions necessary for institutionalization of her charismatic…

  8. Elisabeth Kubler-Ross as a Religious Leader.

    Science.gov (United States)

    Klass, Dennis; Hutch, Richard A.

    1986-01-01

    Considers Elisabeth Kubler-Ross as a charismatic religious leader and examines the feminine quality of her message and leadership style. An examination of the prospects for an enduring cultural innovation based on Kubler-Ross's work concludes that her leadership does not conform to conditions necessary for institutionalization of her charismatic…

  9. Structure of the central Terror Rift, western Ross Sea, Antarctica

    Science.gov (United States)

    Hall, Jerome; Wilson, Terry; Henrys, Stuart

    2007-01-01

    The Terror Rift is a zone of post-middle Miocene faulting and volcanism along the western margin of the West Antarctic Rift System. A new seismic data set from NSF geophysical cruise NBP04-01, integrated with the previous dataset to provide higher spatial resolution, has been interpreted in this study in order to improve understanding of the architecture and history of the Terror Rift. The Terror Rift contains two components, a structurally-controlled rollover anticlinal arch intruded by younger volcanic bodies and an associated synclinal basin. Offsets and trend changes in fault patterns have been identified, coincident with shifts in the location of depocenters that define rift sub-basins, indicating that the Terror Rift is segmented by transverse structures. Multiple phases of faulting all post-date 17 Ma, including faults cutting the seafloor surface, indicating Neogene rifting and possible modern activity.

  10. Mg/Casea surface temperatures during the Marine Isotope Stage 31 collapse of the Ross Ice Shelf

    Science.gov (United States)

    Dunbar, G. B.

    2012-04-01

    The recovery of the AND-1b and CRP-1 drill cores from the Southwest Ross Sea highlighted the potential instability in of the Ross Ice Shelf and the West Antarctic Ice Sheet it buttresses. Both cores recovered a few individuals of the planktonic foraminifera Neogloboquadrina pachyderma from marine isotope stage (MIS) 31. This interval is significant because it marks the youngest occurrence of open ocean diatom sediment at AND-1b, which is now situated under the McMurdo Ice Shelf, indicating a substantial retreat of the Ross Ice Shelf occurred during this interglacial. However, sediment deposited after MIS 31 at both sites is represented only by glacial-dominated sediment, suggesting a critical environmental threshold had been crossed enabling the Ross Ice Shelf to form and persist. Numerical modeling by Pollard and DeConto (Nature, 2009) suggested that sub-ice oceanic melting is a critical element in the stability of ice shelves and that "WAIS will begin to collapse when nearby ocean temperatures warm by roughly 5°C." Laser ablation ICPMS measurement of the Mg/Ca content of N. pachyderma shows that although there is considerable heterogeneity in the distribution of Mg in their tests the mean Mg/Ca of a sample population appears proportional to calcification temperature. By empirically calibrating Mg/Ca in CRP-1 N. pachyderma against values measured in modern populations collected from Ross Sea and Southern Ocean sites with SSTs ranging from 1.2°C to 14°C it is concluded that SST during MIS 31 was warmer than today by 5-9°C, consistent with model projections.

  11. Ross ice shelf cavity circulation, residence time, and melting: Results from a model of oceanic chlorofluorocarbons

    Science.gov (United States)

    Reddy, Tasha E.; Holland, David M.; Arrigo, Kevin R.

    2010-04-01

    Despite their harmful effects in the upper atmosphere, anthropogenic chlorofluorocarbons dissolved in seawater are extremely useful for studying ocean circulation and ventilation, particularly in remote locations. Because they behave as a passive tracer in seawater, and their atmospheric concentrations are well-mixed, well-known, and have changed over time, they are ideal for gaining insight into the oceanographic characteristics of the isolated cavities found under Antarctic ice shelves, where direct observations are difficult to obtain. Here we present results from a modeling study of air-sea chlorofluorocarbon exchange and ocean circulation in the Ross Sea, Antarctica. We compare our model estimates of oceanic CFC-12 concentrations along an ice shelf edge transect to field data collected during three cruises spanning 16 yr. Our model produces chlorofluorocarbon concentrations that are quite similar to those measured in the field, both in magnitude and distribution, showing high values near the surface, decreasing with depth, and increasing over time. After validating modeled circulation and air-sea gas exchange through comparison of modeled temperature, salinity, and chlorofluorocarbons with field data, we estimate that the residence time of water in the Ross Ice Shelf cavity is approximately 2.2 yr and that basal melt rates for the ice shelf average 10 cm yr -1. The model predicts a seasonal signature to basal melting, with highest melt rates in the spring and also the fall.

  12. Drift Scale THM Model

    Energy Technology Data Exchange (ETDEWEB)

    J. Rutqvist

    2004-10-07

    This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because

  13. 北冰洋浮冰和开阔海面上的能量平衡特征%CHARACTERISTICS OF ENERGY BALANCE OVER ARCTIC DRIFTING ICE AND OPEN SEA

    Institute of Scientific and Technical Information of China (English)

    张雅斌; 卞林根; 程彦杰; 陆龙骅

    2000-01-01

    利用中国首次北极考察队于1999年8月19日~24日在北冰洋浮冰区获得的大气近地 层垂直廓线和辐射等资料,依据相似理论方法,对比分析了北冰洋无冰海面和冰面上热平衡参 数的变化特征。结果表明,海面与大气和冰面与大气之间相互作用的边界层物理过程差异十分 明显。冰面吸收的净辐射仅为海面的6%左右,主要消耗于感热输送和冰面融化过程,不足部分 由水汽在冰面上凝结释放的潜热和冰中的热通量来补充。海面吸收的净辐射主要消耗于潜热输 送过程,占净辐射的50%,其余热量传向水体深层和用于感热输送,分别占净辐射的26%和 24%。由此可见,在北冰洋夏季,无冰海面有大量的水汽向大气输送,这对研究北冰洋地区大气 边界层的季节变化过程是至关重要的。%Characteristics of heat balance parameters of Arctic Ocean drifting ice and open sea are presented based on the profile-flux method and the data obtained by the First Chinese National Arctic Research Expedition during Aug. 19-24,1999. The result shows that the difference of interaction processes between ocean-air and ice-air is extremely obvious. Net radiation absorbed by ice surface only account for 6% of that absorbed by the sea surface and it is consumed mainly by the processes of sensible heat exchange and ice melting, deficit part of the heat is compensated from the latent heat released when water vapor is frozen on ice surface and heat stored in ice. Net radiation absorbed by sea surface is balanced most by the process of latent heat transport , accounting for 50% of total heat, and the rest part is conducted to deep water and transported as sensible heat to air, accounting for 26% and 24 % of total heat individually. It can be found that a great quantity of vapor is transported to atmosphere from Arctic Ocean open sea in summer, which is very important to concerns on

  14. Mass Balance and Structure of the Ross Ice Shelf

    Science.gov (United States)

    Das, I.; Padman, L.; Chu, W.; Fricker, H. A.; Becker, M. K.; Bell, R. E.; Tinto, K. J.; Millstein, J. D.

    2016-12-01

    Changes in ice shelf mass balance is key to the long term stability of the Antarctic ice sheet. Although the most extensive thinning occurs on the Amundsen Sea sector of West Antarctica, recent studies indicate that many other ice shelves are also experiencing widespread thinning. Here, we focus on the Ross Ice Self. An 18-year record (1994-2012) of satellite radar altimetry shows elevation change 1 m/yr across the shelf. Significant variability in ice shelf height on interannual time scales makes it difficult to detect a long-term mass budget trend of this ice shelf. Variability of radar signal penetration into the ice-shelf snow and firn layers further complicates assessment of mass changes. In this work, we investigate the Ross Ice Shelf mass balance using aerogeophyical data from the ROSETTA-ICE IcePod and NASA's Operation IceBridge. ROSSETTA-ICE is an aerogeophysical program planned to survey the ice shelf at a 10 km spacing over the course of two field seasons-2015 and 2016. This NSF/Moore Foundation supported multi-University collaborative project is designed to provide an integrated view of the ice shelf and the underlying bathymetry using the IcePod system including its ice-penetrating radars, laser altimetry, gravity meters and magnetometers. We present preliminary results from our ongoing efforts of quantifying the mass balance of the ice shelf using IcePod ice penetrating radars and laser altimetry along with satellite data. We will use internal layers traced from ice penetrating radars to outline the structure of the ice shelf. Airborne laser altimetry measurements from this IcePod survey and IceBridge will be used to study the elevation change of the ice shelf. Spatial variations of thickness of the internal layers in the first few meters of the ice shelf, particularly near the grounding line, will indicate the impact of wind-blown snow coming from the continent onto the ice shelf. In order to infer conditions of melt and freeze-on at the ice

  15. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  16. SAA drift: Experimental results

    Science.gov (United States)

    Grigoryan, O. R.; Romashova, V. V.; Petrov, A. N.

    According to the paleomagnetic analysis there are variations of Earth’s magnetic field connected with magnetic moment changing. These variations affect on the South Atlantic Anomaly (SAA) location. Indeed different observations approved the existence of the SAA westward drift rate (0.1 1.0 deg/year) and northward drift rate (approximately 0.1 deg/year). In this work, we present the analysis of experimental results obtained in Scobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU) onboard different Earth’s artificial satellites (1972 2003). The fluxes of protons with energy >50 MeV, gamma quanta with energy >500 keV and neutrons with energy 0.1 1.0 MeV in the SAA region have been analyzed. The mentioned above experimental data were obtained onboard the orbital stations Salut-6 (1979), MIR (1991, 1998) and ISS (2003) by the similar experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact that the SAA drifts westward. Moreover the analysis of fluxes of electrons with energy about hundreds keV (Cosmos-484 (1972) and Active (Interkosmos-24, 1991) satellites) verified not only the SAA westward drift but northward drift also.

  17. The Paediatric Cardiology Hall of Fame – Donald Nixon Ross.

    Science.gov (United States)

    Somerville, Jane

    2015-10-01

    Donald Nixon Ross, FRCS (4 October 1922 to 7 July 2014) was a South African-born British cardiothoracic surgeon, who developed the pulmonary autograft, known as the Ross procedure, for the treatment of aortic valve disease, and also performed the first heart transplant in the United Kingdom in 1968. This paper, written by Jane Somerville, Professor of Cardiology [Retired], Imperial College London, London, United Kingdom, provides the personal recollections about Donald Ross from Jane Somerville, and thus provides a unique snapshot of cardiac surgical history.

  18. Drifting organisms in the Precambrian sea

    Science.gov (United States)

    Milton, D.J.

    1966-01-01

    Drag marks in the Upper Precambrian Winnall Beds of central Australia were made by semibuoyant flexible objects at least 15 centimeters long, which presumably were algae. This find extends the range of such marks into the Precambrian era and supplements the discovery of microflora in the same sedimentary sequence.

  19. Histological comparison of layer media thickness of pulmonary arteroides between Cobb-Vantress and Ross broiler chicken exposed to hypoxia

    OpenAIRE

    Vásquez C., María; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú.; Cueva M., Sergio; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Ayón S., Milder; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú.; Lira M., Boris; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Chavera C., Alfonso; Laboratorio de Histología, Embriología y Patología Veterinaria, Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos, Lima; Angulo H., Pedro; Laboratorio de Farmacología y Toxicología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú; Falcón P., Néstor; Facultad de Veterinaria y Zootecnia, Universidad Peruana Cayetano Heredia, Lima

    2012-01-01

    The objective of the present study was to determine the development of the smooth muscle of pulmonary arterioles through the relationship of the smooth muscle layer of pulmonary arteriole/arteriolar diameter (CM/DA). Ninety Cobb-Vantress chicks and 90 Ross chicks were used. Of these, 10 birds were weighed and slaughtered at 1 day of age, and the others were randomly distributed in a group raised at sea level (n=40) and a group raised at 3320 m above the sea level (n=40). Ten birds per group w...

  20. Histological comparison of layer media thickness of pulmonary arteroides between Cobb-Vantress and Ross broiler chicken exposed to hypoxia

    OpenAIRE

    Vásquez C., María; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Cueva M., Sergio; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima; Ayón S., Milder; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima Perú.; Lira M., Boris; Laboratorio de Fisiología Animal, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima; Chavera C., Alfonso; Laboratorio de Histología, Embriología y Patología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos, Lima-Perú.; Angulo H., Pedro; Laboratorio de Farmacología y Toxicología Veterinaria, Facultad de Medicina Veterinaria, Universidad Nacional Mayor de San Marcos. Lima, Perú; Falcón P., Néstor; Facultad de Veterinaria y Zootecnia, Universidad Peruana Cayetano Heredia, Lima

    2012-01-01

    The objective of the present study was to determine the development of the smooth muscle of pulmonary arterioles through the relationship of the smooth muscle layer of pulmonary arteriole/arteriolar diameter (CM/DA). Ninety Cobb-Vantress chicks and 90 Ross chicks were used. Of these, 10 birds were weighed and slaughtered at 1 day of age, and the others were randomly distributed in a group raised at sea level (n=40) and a group raised at 3320 m above the sea level (n=40). Ten birds per group w...

  1. Minevikupärandit Häädemeestelt / Eevi Ross

    Index Scriptorium Estoniae

    Ross, Eevi, 1938-

    2012-01-01

    Raamatututvustus: Minevikupärandit Häädemeestelt : valimik korrespondentide murdetekste. VIII / Eesti Teaduste Akadeemia Emakeele Selts ; kogunud Marta Mäesalu ; koostanud ja toimetanud: Helju Kaal, Eevi Ross. Tallinn : Emakeele Selts, 2012

  2. Minevikupärandit Häädemeestelt / Eevi Ross

    Index Scriptorium Estoniae

    Ross, Eevi, 1938-

    2012-01-01

    Raamatututvustus: Minevikupärandit Häädemeestelt : valimik korrespondentide murdetekste. VIII / Eesti Teaduste Akadeemia Emakeele Selts ; kogunud Marta Mäesalu ; koostanud ja toimetanud: Helju Kaal, Eevi Ross. Tallinn : Emakeele Selts, 2012

  3. Folds--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for folds for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included...

  4. Faults--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for faults for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included...

  5. Backscatter A [8101]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  6. ROSS Skills, Knowledge, and Abilities Training Evaluation. Gaps and Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Ala, Maureen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gruidl, Jeremiah [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buddemeier, Brooke [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-30

    This document describes the development of the ROSS SKAs, the cross-mapping of the SKAs to the available training, identifies gaps in the SKA and training, and provides recommendations to address those gaps.

  7. Backscatter B [7125]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  8. Backscatter C [Swath]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  9. The Ross II procedure: pulmonary autograft in the mitral position.

    Science.gov (United States)

    Athanasiou, Thanos; Cherian, Ashok; Ross, Donald

    2004-10-01

    The surgical management of mitral valve disease in women of childbearing age, young patients, and children with congenital mitral valve defects is made difficult by the prospect of lifelong anticoagulation. We suggest the use of a pulmonary autograft in the mitral position (Ross II procedure) as an alternative surgical technique. We present a review of the literature, historical perspectives, indications, selection criteria, and surgical technique for the Ross II procedure. Our literature search identified 14 studies that reported results from the Ross II operation. Performed in 103 patients, the overall in-hospital mortality was 7 (6.7%), with a late mortality of 10 (9%). Although further research is needed, current evidence suggests the Ross II operation is a valuable alternative in low-risk young patients where valve durability and the complication rate from other procedures is unsatisfactory and anticoagulation not ideal.

  10. Backscatter A [8101]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  11. Bathymetry Hillshade--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetry and shaded-relief maps of the Offshore of Fort Ross map area, California. Raster data file is included in...

  12. Backscatter B [7125]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate...

  13. Backscatter C [Swath]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate...

  14. Backscatter A [8101]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate...

  15. Backscatter C [Swath]--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids...

  16. Bathymetry Hillshade--Offshore of Fort Ross, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the bathymetry and shaded-relief maps of the Offshore of Fort Ross map area, California. Raster data file is included in...

  17. Faults--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for faults for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included...

  18. Folds--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for folds for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included...

  19. Negative Drift in Populations

    DEFF Research Database (Denmark)

    Lehre, Per Kristian

    2011-01-01

    An important step in gaining a better understanding of the stochastic dynamics of evolving populations, is the development of appropriate analytical tools. We present a new drift theorem for populations that allows properties of their long-term behaviour, e.g. the runtime of evolutionary algorithms...

  20. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  1. Development of drifting buoys

    Digital Repository Service at National Institute of Oceanography (India)

    Nayak, M.R.; Peshwe, V.B.; Tengali, S.

    . Considerable potential exists for the use of drifting buoys if the cost of data acquisition and processing systems is held at a reasonable level. As yet it is in infancy and further development is required before system reliability and longevity are considered...

  2. Dike Propagation Near Drifts

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2002-03-04

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M&O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M&O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report.

  3. Style drift in private equity

    NARCIS (Netherlands)

    D. Cumming; G. Fleming; A. Schwienbacher

    2009-01-01

    We introduce the concept of style drift to private equity investment. We present theory and evidence pertaining to style drifts in terms of a fund manager's stated focus on particular stages of entrepreneurial development. We develop a model that derives conditions under which style drifts are less

  4. Remote sensing of sea ice: advances during the DAMOCLES project

    Directory of Open Access Journals (Sweden)

    G. Heygster

    2012-12-01

    Full Text Available In the Arctic, global warming is particularly pronounced so that we need to monitor its development continuously. On the other hand, the vast and hostile conditions make in situ observation difficult, so that available satellite observations should be exploited in the best possible way to extract geophysical information. Here, we give a résumé of the sea ice remote sensing efforts of the European Union's (EU project DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies. In order to better understand the seasonal variation of the microwave emission of sea ice observed from space, the monthly variations of the microwave emissivity of first-year and multi-year sea ice have been derived for the frequencies of the microwave imagers like AMSR-E (Advanced Microwave Scanning Radiometer on EOS and sounding frequencies of AMSU (Advanced Microwave Sounding Unit, and have been used to develop an optimal estimation method to retrieve sea ice and atmospheric parameters simultaneously. In addition, a sea ice microwave emissivity model has been used together with a thermodynamic model to establish relations between the emissivities from 6 GHz to 50 GHz. At the latter frequency, the emissivity is needed for assimilation into atmospheric circulation models, but is more difficult to observe directly. The size of the snow grains on top of the sea ice influences both its albedo and the microwave emission. A method to determine the effective size of the snow grains from observations in the visible range (MODIS is developed and demonstrated in an application on the Ross ice shelf. The bidirectional reflectivity distribution function (BRDF of snow, which is an essential input parameter to the retrieval, has been measured in situ on Svalbard during the DAMOCLES campaign, and a BRDF model assuming aspherical particles is developed. Sea ice drift and deformation is derived from satellite observations with the scatterometer

  5. Influence of the Southern Annular Mode on the sea ice-ocean system: the role of the thermal and mechanical forcing

    Directory of Open Access Journals (Sweden)

    W. Lefebvre

    2005-06-01

    Full Text Available The global sea ice-ocean model ORCA2-LIM is used to investigate the impact of the thermal and mechanical forcing associated to the Southern Annular Mode (SAM on the Antarctic sea ice-ocean system. To do so, the model is driven by idealized forcings based on regressions of the wind stress and the air temperature to SAM. The wind-stress component strongly affects the overall patterns of the ocean circulation with a northward surface drift, a downwelling at about 45° S and an upwelling in the vicinity of the Antarctic continent when SAM is positive. On the other hand, the thermal forcing has a negligible effect on the ocean currents. For sea ice, both the wind-stress (mechanical and the air temperature (thermal components have a significant impact. The mechanical part induces a decrease of the sea ice thickness close to the continent and a sharp decrease of the mean sea ice thickness in the Weddell sector. In general, the sea ice area also diminishes, with a maximum decrease in the Weddell Sea. On the contrary, the thermal part tends to increase the ice concentration in all sectors except in the Weddell Sea, where the ice area shrinks. This thermal effect is the strongest in autumn and in winter due to the larger temperature differences associated with SAM during these seasons. The sum of the thermal and mechaninal effects gives a dipole response of sea ice to the SAM, with a decrease of the ice area in the Weddell Sea and around the Antarctic Peninsula and an increase in the Ross and Amundsen Seas during high SAM years. This is in good agreement with the observed response of the ice cover to SAM.

  6. Drift-Diffusion Equation

    Directory of Open Access Journals (Sweden)

    K. Banoo

    1998-01-01

    equation in the discrete momentum space. This is shown to be similar to the conventional drift-diffusion equation except that it is a more rigorous solution to the Boltzmann equation because the current and carrier densities are resolved into M×1 vectors, where M is the number of modes in the discrete momentum space. The mobility and diffusion coefficient become M×M matrices which connect the M momentum space modes. This approach is demonstrated by simulating electron transport in bulk silicon.

  7. Climate variability and Ross River virus transmission.

    Science.gov (United States)

    Tong, S; Bi, P; Donald, K; McMichael, A J

    2002-08-01

    (1) To examine the feasibility to link climate data with monthly incidence of Ross River virus (RRv). (2) To assess the impact of climate variability on the RRv transmission. An ecological time series analysis was performed on the data collected between 1985 to 1996 in Queensland, Australia. Information on the notified RRv cases was obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. Spearman's rank correlation analyses were performed to examine the relation between climate variability and the monthly incidence of notified RRv infections. The autoregressive integrated moving average (ARIMA) model was used to perform a time series analysis. As maximum and minimum temperatures were highly correlated with each other (r(s)=0.75), two separate models were developed. For the eight major cities in Queensland, the climate-RRv correlation coefficients were in the range of 0.12 to 0.52 for maximum and minimum temperatures, -0.10 to 0.46 for rainfall, and 0.11 to 0.52 for relative humidity and high tide. For the whole State, rainfall (partial regression coefficient: 0.017 (95% confidence intervals 0.009 to 0.025) in Model I and 0.018 (0.010 to 0.026) in Model II), and high tidal level (0.030 (0.006 to 0.054) in Model I and 0.029 (0.005 to 0.053) in Model II) seemed to have played significant parts in the transmission of RRv in Queensland. Maximum temperature was also marginally significantly associated with the incidence of RRv infection. Rainfall, temperature, and tidal levels may be important environmental determinants in the transmission cycles of RRv disease.

  8. Investigations of the tropospheric halogen chemistry around Ross Island, Antarctica, during austral spring 2012

    Science.gov (United States)

    Zielcke, Johannes; Pöhler, Denis; Frieß, Udo; Hay, Tim; Kreher, Karin; Kalnajs, Lars; Platt, Ulrich

    2013-04-01

    A unique feature of the polar troposphere is the strong impact of halogen photochemistry, in which reactive halogen species (RHS) are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulphide. The source, however, as well as release and recycling mechanisms of these halogen species are far from being completely understood, especially the role of chlorine and iodine compounds. Reactive chlorine, bromine and iodine compounds are thought to be released from sea salt particles or produced by the photolysis of halocarbons and I2 emitted by the ocean. Here we present observations of halogen oxides, ozone and nitrogen dioxide conducted for three months during austral spring 2012 on Ross Island, Antarctica. Measurements were performed with a suite of remote sensing instruments. An active long-path differential optical absorption spectroscopy (LP-DOAS) system was set up, measuring several species (BrO, O3, NO2, OBrO, IO, OIO, I2, ClO, OClO, CHOCHO, HCHO, HONO) continuously for the whole period, with two light paths over first year sea ice. In addition, a passive MAX-DOAS as well as a new Cavity-Enhanced (CE)-DOAS system were used for mobile halogen oxide measurements on a variety of locations around Ross Island (sea ice, shelf ice, snow, coastal, etc.), with top surface layer pH measurements performed at the different measurement sites. First results show highly variable ozone concentrations including partial Ozone Depletion Events (ODEs), as well as concentrations of BrO up to 16ppt and NO2 up to 15ppb. Suprisingly, a high variation of ozone was observed without significant amounts of BrO, indicating already depleted air masses transported to the measurement site and/or NOx chemistry inhibiting halogen radical reactions.

  9. Radiological Operations Support Specialist (ROSS) Pilot Course Summary and Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Alai, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Askin, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buddemeier, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wogan, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Doshi, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tai, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-30

    In support of the Department of Homeland Security / Science and Technology Directorate’s (DHS/S&T) creation of a new position called the Radiological Operations Support Specialist (ROSS), Lawrence Livermore National Laboratory (LLNL) in Sub-task 1.1 and 1.2 has assisted in the development of the ROSS skills, knowledge, and abilities (SKAs); identified potentially relevant training; cross-mapped the training to the SKAs; and identified gaps in the training related to the SKAs, as well as their respective level of training knowledge - current versus desired. In the follow on task, Sub-task 1.3, a 5 day ROSS Pilot Training course was developed to fill the priority gaps identified in Sub-Task 1.2. Additionally, in Sub-Task 1.5, LLNL has performed a gap analysis of electronic tools, handbooks, and job-aides currently available to the ROSS and developed recommendations for additional and next generation tools to ensure the operational effectiveness of the ROSS position. This document summarizes the feedback received from the instructors and pilot course observers on what worked in the course and what could be improved as well as an assessment of the Pre- and Post-Test administered to the students.

  10. Adaptive Online Sequential ELM for Concept Drift Tackling.

    Science.gov (United States)

    Budiman, Arif; Fanany, Mohamad Ivan; Basaruddin, Chan

    2016-01-01

    A machine learning method needs to adapt to over time changes in the environment. Such changes are known as concept drift. In this paper, we propose concept drift tackling method as an enhancement of Online Sequential Extreme Learning Machine (OS-ELM) and Constructive Enhancement OS-ELM (CEOS-ELM) by adding adaptive capability for classification and regression problem. The scheme is named as adaptive OS-ELM (AOS-ELM). It is a single classifier scheme that works well to handle real drift, virtual drift, and hybrid drift. The AOS-ELM also works well for sudden drift and recurrent context change type. The scheme is a simple unified method implemented in simple lines of code. We evaluated AOS-ELM on regression and classification problem by using concept drift public data set (SEA and STAGGER) and other public data sets such as MNIST, USPS, and IDS. Experiments show that our method gives higher kappa value compared to the multiclassifier ELM ensemble. Even though AOS-ELM in practice does not need hidden nodes increase, we address some issues related to the increasing of the hidden nodes such as error condition and rank values. We propose taking the rank of the pseudoinverse matrix as an indicator parameter to detect "underfitting" condition.

  11. Adaptive Online Sequential ELM for Concept Drift Tackling

    Directory of Open Access Journals (Sweden)

    Arif Budiman

    2016-01-01

    Full Text Available A machine learning method needs to adapt to over time changes in the environment. Such changes are known as concept drift. In this paper, we propose concept drift tackling method as an enhancement of Online Sequential Extreme Learning Machine (OS-ELM and Constructive Enhancement OS-ELM (CEOS-ELM by adding adaptive capability for classification and regression problem. The scheme is named as adaptive OS-ELM (AOS-ELM. It is a single classifier scheme that works well to handle real drift, virtual drift, and hybrid drift. The AOS-ELM also works well for sudden drift and recurrent context change type. The scheme is a simple unified method implemented in simple lines of code. We evaluated AOS-ELM on regression and classification problem by using concept drift public data set (SEA and STAGGER and other public data sets such as MNIST, USPS, and IDS. Experiments show that our method gives higher kappa value compared to the multiclassifier ELM ensemble. Even though AOS-ELM in practice does not need hidden nodes increase, we address some issues related to the increasing of the hidden nodes such as error condition and rank values. We propose taking the rank of the pseudoinverse matrix as an indicator parameter to detect “underfitting” condition.

  12. A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled.

    Science.gov (United States)

    Nappi, Francesco; Spadaccio, Cristiano; Fraldi, Massimiliano; Montagnani, Stefania; Fouret, Pierre; Chachques, Juan Carlos; Acar, Christophe

    2016-01-01

    Use of resorbable external reinforcement of the pulmonary autograft during the Ross operation has been suggested, but the differential regional potential for dilation of the aorta, mainly regarding the neo-root and the neo-Valsalva sinuses, represents an unresolved issue. Auxetic materials could be useful in preventing dilation given their favorable mechanical properties. We designed a composite semiresorbable armoured bioprosthesis constituted by polydioxanone and expanded polytetrafluoroethylene and evaluated its effectiveness as a pulmonary autograft reinforcement device in an animal model of the Ross procedure. An experimental model of the Ross procedure was performed in 20 three-month-old growing lambs. The pulmonary autograft was alternatively nonreinforced (control group n = 10) or reinforced with composite bioprosthesis (reinforced group n = 10). Animals were followed up during growth for 6 months by angiography and echocardiography. Specific stainings for extracellular matrix and immunohistochemistry for metalloproteinase-9 were performed. Reference aortic diameter increased from 14 ± 1 mm to 19 ± 2 mm over 6 months of growth. In the control group, pulmonary autograft distension (28 ± 2 mm) was immediately noted, followed by aneurysm development at 6 months (40 ± 2 mm, P < .001 vs reference). In the reinforced group, an initial dilation to 18 ± 1 mm was detected and the final diameter was 27 ± 2 mm (42% increase). Two deaths due to pulmonary autograft rupture occurred in the control group. On histology, the control group showed medial disruption with connective fibrous replacement, whereas in the reinforced group compensatory intimal hyperplasia was present in the absence of intimal tears. The bioprosthesis promoted a positive matrix rearrangement process favoring neoarterialization and elastic remodeling as demonstrated on specific staining for elastin collagen and metalloproteinase-9. The device adapted and functionally compensated for the

  13. The relevance of buttressing for Filchner-Ronne and Ross Ice Shelf

    Science.gov (United States)

    Reese, Ronja; Gudmundsson, Hilmar; Levermann, Anders; Winkelmann, Ricarda

    2016-04-01

    Sub-shelf melting is an important component of Antarctica's mass budget. Although thinning of ice shelves does not directly contribute to sea-level rise, it may have a significant indirect impact through the potential of ice shelves to buttress their adjacent ice sheet. This is clearly seen in recent observations, e.g. in the Amundsen region (Pritchard et al., 2012) or at the Southern Antarctic Peninsula (Wouters et al, 2015) where increased ice loss of the adjacent upstream drainage basins is attributed to enhanced sub-shelf melting. In the extreme case, the complete disintegration of an ice shelf, e.g. during the calving events of Larsen A and B in 1995 and 2002, respectively, the adjacent ice streams subsequently accelerated significantly (Scambos et al., 2014). Here, we investigate the importance of buttressing using the finite-element, shallow-stream approximation numerical model Úa. We derive transfer functions for an idealized setup (Gudmundsson et al. 2012) and the Filchner-Ronne and Ross Ice Shelf. They allow for the computation of instantaneous changes in velocities to thickness perturbation patterns. Based on the transfer functions, we calculate the sensitivity of flux across the grounding line to regional varying melting patterns for the idealized setup and for Filchner-Ronne and Ross Ice Shelf. We find that the immediate response of velocities in the ice shelf-ice sheet system to changes in sub-shelf melting can be understood as the interaction of two effects: On the one hand, the spreading rate is a function of local ice thickness, indicating that a thinning of the ice shelf reduces velocities. On the other hand, ice shelf thinning weakens its ability to buttress, and thus enhances velocities. These two processes compete, leading to a complex pattern of velocity changes within the ice shelf. We find - both in the idealized setup and for Ross and Filchner-Ronne Ice Shelves - that the reduction in buttressing is dominating the velocity changes in the

  14. Fingermark ridge drift.

    Science.gov (United States)

    De Alcaraz-Fossoul, Josep; Roberts, Katherine A; Feixat, Carme Barrot; Hogrebe, Gregory G; Badia, Manel Gené

    2016-01-01

    Distortions of the fingermark topography are usually considered when comparing latent and exemplar fingerprints. These alterations are characterized as caused by an extrinsic action, which affects entire areas of the deposition and alters the overall flow of a series of contiguous ridges. Here we introduce a novel visual phenomenon that does not follow these principles, named fingermark ridge drift. An experiment was designed that included variables such as type of secretion (eccrine and sebaceous), substrate (glass and polystyrene), and degrees of exposure to natural light (darkness, shade, and direct light) indoors. Fingermarks were sequentially visualized with titanium dioxide powder, photographed and analyzed. The comparison between fresh and aged depositions revealed that under certain environmental conditions an individual ridge could randomly change its original position regardless of its unaltered adjacent ridges. The causes of the drift phenomenon are not well understood. We believe it is exclusively associated with intrinsic natural aging processes of latent fingermarks. This discovery will help explain the detection of certain dissimilarities at the minutiae/ridge level; determine more accurate "hits"; identify potentially erroneous corresponding points; and rethink identification protocols, especially the criteria of "no single minutiae discrepancy" for a positive identification.

  15. The CLEO III drift chamber

    CERN Document Server

    Peterson, D; Briere, R A; Chen, G; Cronin-Hennessy, D; Csorna, S; Dickson, M; Dombrowski, S V; Ecklund, K M; Lyon, A; Marka, S; Meyer, T O; Patterson, J R; Sadoff, A; Thies, P; Thorndike, E H; Urner, D

    2002-01-01

    The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to 79 cm, the new drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to 88 mu m (averaged over the full drift range).

  16. Wind tunnel observations of drifting snow

    Science.gov (United States)

    Paterna, Enrico; Crivelli, Philip; Lehning, Michael

    2016-04-01

    Drifting snow has a significant impact on snow redistribution in mountains, prairies as well as on glaciers, ice shelves, and sea ice. In all these environments, the local mass balance is highly influenced by drifting snow. Understanding the dynamic of snow saltation is crucial to the accurate description of the process. We applied digital shadowgraphy in a cold wind tunnel to measure drifting snow over natural snow covers. The acquisition and evaluation of time-resolved shadowgraphy images allowed us to resolve a large part of the saltation layer. The technique has been successfully compared to the measurements obtained from a Snow Particle Counter, considered the most robust technique for snow mass-flux measurements so far. The streamwise snow transport is dominated by large-scale events. The vertical snow transport has a more equal distribution of energy across the scales, similarly to what is observed for the flow turbulence velocities. It is hypothesized that the vertical snow transport is a quantity that reflects the local entrainment of the snow crystals into the saltation layer while the streamwise snow transport results from the streamwise development of the trajectories of the snow particles once entrained, and therefore is rather a non-local quantity.

  17. The DRIFT Dark Matter Experiments

    CERN Document Server

    Daw, E; Fox, J R; Gauvreau, J -L; Ghag, C; Harmon, L J; Harton, J L; Gold, M; Lee, E R; Loomba, D; Miller, E H; Murphy, A St J; Paling, S M; Landers, J M; Phan, N; Pipe, M; Pushkin, K; Robinson, M; Sadler, S W; Snowden-Ifft, D P; Spooner, N J C; Walker, D; Warner, D

    2011-01-01

    The current status of the DRIFT (Directional Recoil Identification From Tracks) experiment at Boulby Mine is presented, including the latest limits on the WIMP spin-dependent cross-section from 1.5 kg days of running with a mixture of CS2 and CF4. Planned upgrades to DRIFT IId are detailed, along with ongoing work towards DRIFT III, which aims to be the world's first 10 m3-scale directional Dark Matter detector.

  18. Antarctic sea ice increase consistent with intrinsic variability of the Amundsen Sea Low

    Science.gov (United States)

    Turner, John; Hosking, J. Scott; Marshall, Gareth J.; Phillips, Tony; Bracegirdle, Thomas J.

    2016-04-01

    We investigate the relationship between atmospheric circulation variability and the recent trends in Antarctic sea ice extent (SIE) using Coupled Model Intercomparison Project Phase 5 (CMIP5) atmospheric data, ECMWF Interim reanalysis fields and passive microwave satellite data processed with the Bootstrap version 2 algorithm. Over 1979-2013 the annual mean total Antarctic SIE increased at a rate of 195 × 103 km2 dec-1 (1.6 % dec-1), p 4.0 % dec-1) has been in the Ross Sea sector. Off West Antarctica there is a high correlation between trends in SIE and trends in the near-surface winds. The Ross Sea SIE seasonal trends are positive throughout the year, but largest in spring. The stronger meridional flow over the Ross Sea has been driven by a deepening of the Amundsen Sea Low (ASL). Pre-industrial control and historical simulations from CMIP5 indicate that the observed deepening of the ASL and stronger southerly flow over the Ross Sea are within the bounds of modeled intrinsic variability. The spring trend would need to continue for another 11 years for it to fall outside the 2 standard deviation range seen in 90 % of the simulations.

  19. Thermohaline circulation below the Ross Ice Shelf - A consequence of tidally induced vertical mixing and basal melting

    Science.gov (United States)

    Macayeal, D. R.

    1984-01-01

    The warmest water below parts of the Ross Ice Shelf resides in the lowest portion of the water column because of its high salinity. Vertical mixing caused by tidal stirring can thus induce ablation by lifting the warm but dense water into contact with the ice shelf. A numerical tidal simulation indicates that vertically well-mixed conditions predominate in the southeastern part of the sub-ice shelf cavity, where the water column thickness is small. Basal melting in this region is expected to be between 0.05 and 0.5 m/yr and will drive a thermohaline circulation having the following characteristics: high salinity shelf water (at - 1.8 C), formed by winter sea ice production in the open Ross Sea, flows along the seabed toward the tidal mixing fronts below the ice shelf; and meltwater (at -2.2 C), produced in the well-mixed region, flows out of the sub-ice shelf cavity along the ice shelf bottom. Sensitivity of this ablation process to climatic change is expected to be small because high salinity shelf water is constrained to have the sea surface freezing temperature.

  20. 76 FR 22338 - Proposed Fort Ross-Seaview Viticultural Area; Comment Period Reopening

    Science.gov (United States)

    2011-04-21

    ... Alcohol and Tobacco Tax and Trade Bureau 27 CFR Part 9 RIN 1513-AB44 Proposed Fort Ross-Seaview... the Fort Ross-Seaview viticultural area in western Sonoma County, California. Through this notice, TTB is soliciting comments on the establishment of the Fort Ross-Seaview viticultural area as proposed...

  1. 77 FR 56859 - Federal Register Notification of Redesignation of Potential Wilderness as Wilderness, Ross Lake...

    Science.gov (United States)

    2012-09-14

    ..., Ross Lake National Recreation Area, North Cascades National Park Service Complex, Washington AGENCY... acres of North Cascades National Park, Ross Lake National Recreation Area, and Lake Chelan National... also designated an additional 5,226 acres of potential wilderness within Ross Lake National...

  2. The KLOE drift chamber

    Energy Technology Data Exchange (ETDEWEB)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; Lucia, E. De; Robertis, G. De; Sangro, R. De; Simone, P. De; Zorzi, G. De; Dell' Agnello, S.; Denig, A.; Domenico, A. Di; Donato, C. Di; Falco, S. Di; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U.V.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P. E-mail: paolo.valente@lnf.infn.it; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y

    2001-04-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K{sub L} produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm{sup 2} in size in the 12 innermost layers and 3x3 cm{sup 2} in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented.

  3. High rate drift chambers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, D.C. (Fermilab, Batavia, IL 60510 (United States)); Berisso, M.C. (Fermilab, Batavia, IL 60510 (United States)); Gutierrez, G. (Fermilab, Batavia, IL 60510 (United States)); Holmes, S.D. (Fermilab, Batavia, IL 60510 (United States)); Wehmann, A. (Fermilab, Batavia, IL 60510 (United States)); Avilez, C. (Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico)); Felix, J. (Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico)); Moreno, G. (Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico)); Romero, M. (Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico)); Sosa, M. (Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico)); Forbush, M. (Department of Physics, Texas A and M University, College Station, TX 77843 (United States)); Huson, F.R. (Department of Physics, Texas A and M University, College Station, TX 77843 (United States)); Wightman, J.A. (Department of Physi

    1994-06-01

    Fermilab experiment 690, a study of target dissociation reactions pp[yields]pX using an 800 GeV/c proton beam and a liquid hydrogen target, collected data in late 1991. The incident beam and 600-800 GeV/c scattered protons were measured using a system of six 6 in.x4 in. and two 15 in.x8 in. pressurized drift chambers spaced over 260 m. These chambers provided precise measurements at rates above 10 MHz (2 MHz per cm of sense wire). The measurement resolution of the smaller chambers was 90 [mu]m, and the resolution of the larger chambers was 125 [mu]m. Construction details and performance results, including radiation damage, are presented. ((orig.))

  4. The KLOE drift chamber

    CERN Document Server

    Adinolfi, M; Ambrosino, F; Andryakov, A; Antonelli, A; Antonelli, M; Anulli, F; Bacci, C; Bankamp, A; Barbiellini, G; Bellini, F; Bencivenni, G; Bertolucci, Sergio; Bini, C; Bloise, C; Bocci, V; Bossi, F; Branchini, P; Bulychjov, S A; Cabibbo, G; Calcaterra, A; Caloi, R; Campana, P; Capon, G; Carboni, G; Cardini, A; Casarsa, M; Cataldi, G; Ceradini, F; Cervelli, F; Cevenini, F; Chiefari, G; Ciambrone, P; Conetti, S; Conticelli, S; Lucia, E D; Robertis, G D; Sangro, R D; Simone, P D; Zorzi, G D; Dell'Agnello, S; Denig, A; Domenico, A D; Donato, C D; Falco, S D; Doria, A; Drago, E; Elia, V; Erriquez, O; Farilla, A; Felici, G; Ferrari, A; Ferrer, M L; Finocchiaro, G; Forti, C; Franceschi, A; Franzini, P; Gao, M L; Gatti, C; Gauzzi, P; Giovannella, S; Golovatyuk, V; Gorini, E; Grancagnolo, F; Grandegger, W; Graziani, E; Guarnaccia, P; Von Hagel, U; Han, H G; Han, S W; Huang, X; Incagli, M; Ingrosso, L; Jang, Y Y; Kim, W; Kluge, W; Kulikov, V; Lacava, F; Lanfranchi, G; Lee-Franzini, J; Lomtadze, F; Luisi, C; Mao Chen Sheng; Martemyanov, M; Matsyuk, M; Mei, W; Merola, L; Messi, R; Miscetti, S; Moalem, A; Moccia, S; Moulson, M; Müller, S; Murtas, F; Napolitano, M; Nedosekin, A; Panareo, M; Pacciani, L; Pagès, P; Palutan, M; Paoluzi, L; Pasqualucci, E; Passalacqua, L; Passaseo, M; Passeri, A; Patera, V; Petrolo, E; Petrucci, Guido; Picca, D; Pirozzi, G; Pistillo, C; Pollack, M; Pontecorvo, L; Primavera, M; Ruggieri, F; Santangelo, P; Santovetti, E; Saracino, G; Schamberger, R D; Schwick, C; Sciascia, B; Sciubba, A; Scuri, F; Sfiligoi, I; Shan, J; Silano, P; Spadaro, T; Spagnolo, S; Spiriti, E; Stanescu, C; Tong, G L; Tortora, L; Valente, E; Valente, P; Valeriani, B; Venanzoni, G; Veneziano, Stefano; Wu, Y; Xie, Y G; Zhao, P P; Zhou, Y

    2001-01-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K sub L produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm sup 2 in size in the 12 innermost layers and 3x3 cm sup 2 in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented.

  5. Quaternary Contourite Drifts of the Western Spitsbergen Margin

    Science.gov (United States)

    Laberg, J. S.; Rebesco, M.; Wahlin, A.; Schauer, U.; Beszczynska-Möller, A.; Lucchi, R. G.; Noormets, R.; Accettella, D.; Zarayskaya, Y.; Diviacco, P.

    2014-12-01

    The study of contourite drifts is an increasingly used tool for understanding the climate history of the oceans. In this paper we analyse two contourite drifts along the continental margin west of Spitsbergen, just south of the Fram Strait where significant water mass exchanges impact the Arctic climate. We detail the internal geometry and the morphologic characteristics of the two drifts on the base of multichannel seismic reflection data, sub-bottom profiles and bathymetry. These mounded features, that we propose to name Isfjorden and Bellsund drifts, are located on the continental slope between 1200 and 1800 m depth, whereas the upper slope is characterized by reduced- or non-deposition. The more distinct Isfjorden Drift is about 25 km wide and 45 km long, and over 200 ms TWT thick. We revise the 13 years-long time series of velocity, temperature, and salinity obtained from a mooring array across the Fram Strait. Two distinct current cores are visible in the long-term average. The shallower current core has an average northward velocity of about 20 cm/s, while the deeper bottom current core at about 1450 m depth has an average northward velocity of about 9 cm/s. We consider Norwegian Sea Deep Water episodically ventilated by relatively dense and turbid shelf water from the Barents Sea responsible for the accumulation of the contourites. The onset of the drift growth west of Spitsbergen is inferred to be about 1.3 Ma and related to the Early Pleistocene glacial expansion recorded in the area. The lack of mounded contouritic deposits on the continental slope of the Storfjorden is related to consecutive erosion by glacigenic debris flows. The Isfjorden and Bellsund drifts are inferred to contain the record of the regional palaeoceanography and glacial history and may constitute an excellent target of future scientific drilling.

  6. Ross Ice Shelf and the Queen Maude Mounains, Antarctica

    Science.gov (United States)

    1991-01-01

    Part of the Ross Ice Shelf and the Queen Maude Mounains of Antarctica (55.5N, 178.0W) are in the background of this scene, oriented toward the south. Low stratocumulus clouds are predominant throughout most of the scene.

  7. Abundances in the metal poor dwarf Ross 451

    Science.gov (United States)

    Spiesman, William J.

    1990-01-01

    High dispersion echelle spectra of the high velocity subdwarf Ross 451 (= G236-080) were obtained using the 4-m telescope at Kitt Peak. Initial abundance determinations for six elements are presented, using absolute oscillator strengths and metal-poor stellar-atmosphere models.

  8. A time inhomogeneous Cox-Ingersoll-Ross diffusion with jumps

    CERN Document Server

    Hoepfner, Reinhard

    2009-01-01

    We consider a time inhomogeneous Cox-Ingersoll-Ross diffusion with positive jumps. We exploit a branching property to prove existence of a unique strong solution under a restrictive condition on the jump measure. We give Laplace transforms for the transition probabilities, with an interpretation in terms of limits of mixtures over Gamma laws.

  9. DRIFT EFFECTS IN HGCDTE DETECTORS

    Directory of Open Access Journals (Sweden)

    B. PAVAN KUMAR

    2013-08-01

    Full Text Available The characteristics of temporal drift in spectral responsivity of HgCdTe photodetectors is investigated and found to have an origin different from what has been reported in literature. Traditionally, the literature attributes the cause of drift due to the deposition of thin film of ice water on the active area of the cold detector. The source of drift as proposed in this paper is more critical owing to the difficulties in acquisition of infrared temperature measurements. A model explaining the drift phenomenon in HgCdTe detectors is described by considering the deep trapping of charge carriers and generation of radiation induced deep trap centers which are meta-stable in nature. A theoretical model is fitted to the experimental data. A comparison of the model with the experimental data shows that the radiation induced deep trap centers and charge trapping effects are mainly responsible for the drift phenomenon observed in HgCdTe detectors.

  10. Bouchaud walks with variable drift

    CERN Document Server

    Parra, Manuel Cabezas

    2010-01-01

    In this paper we study a sequence of Bouchaud trap models on $\\mathbb{Z}$ with drift. We analyze the possible scaling limits for a sequence of walks, where we make the drift decay to 0 as we rescale the walks. Depending on the speed of the decay of the drift we obtain three different scaling limits. If the drift decays slowly as we rescale the walks we obtain the inverse of an \\alpha$-stable subordinator as scaling limit. If the drift decays quickly as we rescale the walks, we obtain the F.I.N. diffusion as scaling limit. There is a critical speed of decay separating these two main regimes, where a new process appears as scaling limit. This critical speed is related to the index $\\alpha$ of the inhomogeneity of the environment.

  11. CTF Void Drift Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gosdin, Chris [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gergar, Marcus [Pennsylvania State Univ., University Park, PA (United States)

    2015-10-26

    This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

  12. A Hydrographic Survey of the Scotia Sea, 15 March 1999 to 22 April 1999 (NODC Accession 0000861)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD and chemical data were collected using CTD and bottle casts in the Drake Passage and Scotia Sea from the JAMES CLARK ROSS. Data were collected from 15 March 1999...

  13. Spatial-temporal characters of Antarctic sea ice variation

    Institute of Scientific and Technical Information of China (English)

    Ma Lijuan; Lu Longhua; Bian Lingen

    2004-01-01

    Using sea ice concentration dataset covering the period of 1968-2002 obtained from the Hadley Center of UK, this paper investigates characters of Antarctic sea ice variations .The finding demonstrates that the change of mean sea-ice extent is almost consistent with that of sea-ice area, so sea-ice extent can be chosen to go on this research. The maximum and the minimum of Antarctic sea ice appear in September and February respectively. The maximum and the maximal variation of sea ice appear in Weddell Sea and Ross Sea, while the minimum and the minimal variation of sea-ice appear in Antarctic Peninsula. In recent 35 years, as a whole, Antarctic sea ice decreased distinctly. Moreover, there are 5 subdivision characteristic regions considering their different variations. Hereinto, the sea-ice extent of Weddell Sea and Ross Sea regions extends and area increases, while the sea-ice extent of the other three regions contracts and area decreases. They are all of obvious 2-4 years and 5-7 years significant oscillation periods. It is of significance for further understanding the sea-ice-air interaction in Antarctica region and discussing the relationship between sea-ice variation and atmospheric circulation.

  14. Hemoglobin Drift after Cardiac Surgery

    Science.gov (United States)

    George, Timothy J.; Beaty, Claude A.; Kilic, Arman; Haggerty, Kara A.; Frank, Steven M.; Savage, William J.; Whitman, Glenn J.

    2013-01-01

    Introduction Recent literature suggests that a restrictive approach to red blood cell transfusions is associated with improved outcomes in cardiac surgery (CS) patients. Even in the absence of bleeding, intravascular fluid shifts cause hemoglobin levels to drift postoperatively, possibly confounding the decision to transfuse. We undertook this study to define the natural progression of hemoglobin levels in postoperative CS patients. Methods We included all CS patients from 10/10-03/11 who did not receive a postoperative transfusion. Primary stratification was by intraoperative transfusion status. Change in hemoglobin was evaluated relative to the initial postoperative hemoglobin. Maximal drift was defined as the maximum minus the minimum hemoglobin for a given hospitalization. Final drift was defined as the difference between initial and discharge hemoglobin. Results Our final cohort included 199 patients, 71(36%) received an intraoperative transfusion while 128(64%) did not. The average initial and final hemoglobin for all patients were 11.0±1.4g/dL and 9.9±1.3g/dL, respectively, an final drift of 1.1±1.4g/dL. The maximal drift was 1.8±1.1g/dL and was similar regardless of intraoperative transfusion status(p=0.9). Although all patients’ hemoglobin initially dropped, 79% of patients reached a nadir and experienced a mean recovery of 0.7±0.7g/dL by discharge. On multivariable analysis, increasing CPB time was significantly associated with total hemoglobin drift(Coefficient/hour: 0.3[0.1–0.5]g/dL, p=0.02). Conclusions In this first report of hemoglobin drift following CS, although all postoperative patients experienced downward hemoglobin drift, 79% of patients exhibited hemoglobin recovery prior to discharge. Physicians should consider the eventual upward hemoglobin drift prior to administering red cell transfusions. PMID:22609121

  15. Silicon Drift Detectors for ALICE

    CERN Document Server

    Navach, F; CERN. Geneva

    1992-01-01

    The Silicon Drift Detector (SDD) is a semiconductor, not yet extensively used in HEP experiment, which has an excellent spatial resolution and granularity about comparable to a pixel device requiring a number of readout channels two order of magnitude less.

  16. Isad ja tütred, isad ja pojad / Jüri Ross, Kristine Ross, Fjodor Berman ...[jt.] ; üles kirjutanud Jaana Liigand

    Index Scriptorium Estoniae

    2011-01-01

    Büroomaailma juht Jüri Ross ja turundusdirektor Kristine Ross, BLRT Grupi omanik Fjodor Berman ja BLRT Grupi tütarfirma Refonda tegevdirektor Mark Berman, Saaremaa Laevakompanii ja paljude firmade omanik Vjatšeslav Leedo ja Mosaiigi kohviku omanik Katrin Leedo ärist, juhtimisest ja omavahelistest suhetest

  17. Isad ja tütred, isad ja pojad / Jüri Ross, Kristine Ross, Fjodor Berman ...[jt.] ; üles kirjutanud Jaana Liigand

    Index Scriptorium Estoniae

    2011-01-01

    Büroomaailma juht Jüri Ross ja turundusdirektor Kristine Ross, BLRT Grupi omanik Fjodor Berman ja BLRT Grupi tütarfirma Refonda tegevdirektor Mark Berman, Saaremaa Laevakompanii ja paljude firmade omanik Vjatšeslav Leedo ja Mosaiigi kohviku omanik Katrin Leedo ärist, juhtimisest ja omavahelistest suhetest

  18. ROSS: An Object-Oriented Language for Constructing Simulations.

    Science.gov (United States)

    1984-12-01

    W. Giarla, S. Narain, E. Cesar , and S. Turner, R-3158-AF, October 1984. Fast Concurrent Simulation Using the Time Warp Mechanism, Part I: Local Contru... Villanueva , and H. M. Markowitz, The Simscript H Pmoramming Language, Prentice-Hall, Englewood Cliffs, New Jersey, 1968. Klahr, P., J. Ellis, W. Giarla, S...Narain, E. Cesar , and S. Turner, TWIRL Tactical Warfare in the ROSS Lanuage, The Rand Corporation, R.3158-AF, October 1984. Klahr, P., and W. S

  19. The Drifting Star

    Science.gov (United States)

    2008-04-01

    By studying in great detail the 'ringing' of a planet-harbouring star, a team of astronomers using ESO's 3.6-m telescope have shown that it must have drifted away from the metal-rich Hyades cluster. This discovery has implications for theories of star and planet formation, and for the dynamics of our Milky Way. ESO PR Photo 09a/08 ESO PR Photo 09a/08 Iota Horologii The yellow-orange star Iota Horologii, located 56 light-years away towards the southern Horologium ("The Clock") constellation, belongs to the so-called "Hyades stream", a large number of stars that move in the same direction. Previously, astronomers using an ESO telescope had shown that the star harbours a planet, more than 2 times as large as Jupiter and orbiting in 320 days (ESO 12/99). But until now, all studies were unable to pinpoint the exact characteristics of the star, and hence to understand its origin. A team of astronomers, led by Sylvie Vauclair from the University of Toulouse, France, therefore decided to use the technique of 'asteroseismology' to unlock the star's secrets. "In the same way as geologists monitor how seismic waves generated by earthquakes propagate through the Earth and learn about the inner structure of our planet, it is possible to study sound waves running through a star, which forms a sort of large, spherical bell," says Vauclair. The 'ringing' from this giant musical instrument provides astronomers with plenty of information about the physical conditions in the star's interior. And to 'listen to the music', the astronomers used one of the best instruments available. The observations were conducted in November 2006 during 8 consecutive nights with the state-of-the-art HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla. Up to 25 'notes' could be identified in the unique dataset, most of them corresponding to waves having a period of about 6.5 minutes. These observations allowed the astronomers to obtain a very precise portrait of Iota Horologii: its

  20. Unique manifestations of mixed-phase cloud microphysics over Ross Island and the Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Scott, Ryan C.; Lubin, Dan

    2016-03-01

    Spaceborne radar and lidar observations from the CloudSat and CALIPSO satellites are used to compare seasonal variations in the microphysical and radiative properties of clouds over Ross Island, Antarctica, with two contrasting Arctic atmospheric observatories located in Barrow, Alaska, and Summit, Greenland. At Ross Island, downstream from recurrent intrusions of marine air over the West Antarctic Ice Sheet and eastern Ross Ice Shelf, clouds exhibit a tendency toward the greatest geometrical thickness and coldest temperatures in summer, the largest average ice water content, IWC, at low altitude during summer and autumn, the most abundant IWC at cold mixed-phase temperatures (-40°C

  1. Cirurgia de Ross em crianças Ross procedure in children

    Directory of Open Access Journals (Sweden)

    Valdester Cavalcante PINTO Jr

    1999-04-01

    Full Text Available Objetivo: Os substitutos valvares atuais não preenchem os requisitos de uma prótese ideal. A técnica de Ross tenta oferecer, principalmente às crianças, um auto-enxerto em posição aórtica, livre de eventos tromboembólicos, hemólise e com excepcional durabilidade. O homoenxerto em posição pulmonar também tem mostrado bom desempenho a longo prazo. Nosso objetivo é demonstrar a viabilidade da técnica e os resultados da experiência inicial com o procedimento. Casuística e Métodos: Foram operados entre jan/97 e dez/98, 12 pacientes. Insuficiência aórtica - 5 casos, insuficiência aórtica e mitral - 3 casos, insuficiência aórtica e membrana subaórtica - 2 casos, estenose aórtica - 1 caso, reoperação de plastia da valva aórtica - 1 caso. O sexo predominante foi o masculino (75%. A idade variou de 8 a 15 anos (M = 12,17±2,04. A classe funcional III representou 58,3% e II 41,7%. A avaliação pré-operatória foi realizada com auxílio do ecocardiograma e pós-operatória com ecocardiograma e cateterismo cardíaco. Os homoenxertos utilizados foram mantidos em solução preservante antibiótica. Os procedimentos foram realizados com circulação extracorpórea e cardioplegia cristalóide gelada. Resultados: As intercorrências foram: febre 75%, insuficiência cardíaca congestiva (ICC 25%, hipertensão arterial sistêmica (HAS 33,3%, sangramento 8,33%, hipersecreção pulmonar 8,33% e isquemia miocárdica 8,33%. Ecocardiograma pós-operatório demonstrou insuficiência aórtica discreta em 4 casos. Angiocardiografia evidenciou ausência de insuficiência aórtica ou pulmonar, gradiente VE-Ao em 2 casos (16 mmHg e 9 mmHg e gradiente VD-TP em 2 casos (13,5 mmHg e 9,5 mmHg. Encontram-se em classe funcional I (91,6% e II (8,4%. Conclusões: A técnica é eficaz, reprodutível e de baixa mortalidade. É necessário maior tempo de acompanhamento para avaliação dos enxertos.Current prosthetic replacement for aortic valve disease

  2. Influence of the West Antarctic Ice Sheet and its collapse on the wind and precipitation regimes of the Ross Embayment

    Science.gov (United States)

    Seles, D.; Kowalewski, D. E.

    2015-12-01

    Marine Isotope Stage 31 (MIS 31) is a key analogue for current warming trends yet the extent of the East Antarctic Ice Sheet (EAIS) and the West Antarctic Ice Sheet (WAIS) during this interglacial remains unresolved. Inconsistencies persist between offshore records (suggesting the instability of WAIS) and McMurdo Dry Valley (MDV) terrestrial datasets (indicating long-term ice sheet stability). Here we use a high-resolution regional scale climate model (RegCM3_Polar) to reconstruct paleoclimate during MIS 31 (warm orbit, 400 ppm CO2) and assess changes in precipitation and winds (including katabatic) with WAIS present versus WAIS absent. The MIS 31 scenario with WAIS present resulted in minimal changes in wind magnitude compared with current climate conditions. With WAIS absent, the model predicts a decrease in coastal and highland monthly mean average wind velocities. The greatest rates of snowfall remain along the coast but shift towards higher latitudes with the interior continent remaining dry when WAIS is removed. Focusing on the Ross Embayment, this decreased monthly mean wind velocity and shift of winds to the east indicate a greater influence of offshore winds from the Ross Sea, enabling the increase of precipitation southward along the Transantarctic Mountains (TAM) (i.e. MDV). The apparent decrease of katabatic winds with no WAIS implies that offshore winds may be responsible for bringing the warmer, wetter air into the TAM. The change in wind and precipitation in the Ross Embayment and specifically the MDV highlights the impact of WAIS on Antarctic climate and its subsequent influence on the mass balance of peripheral EAIS domes (i.e. Taylor Dome). Modeling suggests that if WAIS was absent during MIS 31, we would expect (1) greater accumulation at such domes and (2) MDV terrestrial records that reflect a wetter climate, and (3) weaker winds suggesting possibly lower ablation/erosion rates compared to if WAIS was present.

  3. In-Drift Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    D. Jolley

    2000-11-09

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses.

  4. Modelling Southern Ocean iceberg drift and decay with FESOM-IB

    OpenAIRE

    Rackow, Thomas; Wesche, Christine; Timmermann, Ralph; Juricke, Stephan

    2013-01-01

    Icebergs are commonly ignored in current general circulation models despite their connections to ocean stratification, phytoplankton growth and redistribution of freshwater in the Southern Ocean. On the way to fully including icebergs in ocean circulation models, we present FESOM-IB, the high resolution Finite Element Sea Ice - Ocean Model (FESOM) enhanced by an IceBerg drift and decay module developed at AWI Bremerhaven. By solving the momentum equations for iceberg drift, ...

  5. Drift tubes of Linac 2

    CERN Multimedia

    1977-01-01

    With the advent of the 800 MeV PS Booster in 1972, the original injector of the PS, a 50 MeV Alvarez-type proton linac, had reached its limits, in terms of intensity and stability. In 1973 one therefore decided to build a new linac (Linac 2), also with a drift-tube Alvarez structure and an energy of 50 MeV. It had a new Cockcroft-Walton preinjector with 750 keV, instead of the previous one with 500 keV. Linac 2 was put into service in 1980. The old Linac 1 was then used for the study of, and later operation with, various types of ions. This picture shows Linac 2 drift-tubes, suspended on stems coming from the top, in contrast to Linac 1, where the drift-tubes stood on stems coming from the bottom.

  6. The CLAS drift chamber system

    CERN Document Server

    Mestayer, M D; Asavapibhop, B; Barbosa, F J; Bonneau, P; Christo, S B; Dodge, G E; Dooling, T; Duncan, W S; Dytman, S A; Feuerbach, R; Gilfoyle, G P; Gyurjyan, V; Hicks, K H; Hicks, R S; Hyde-Wright, C E; Jacobs, G; Klein, A; Klein, F J; Kossov, M; Kuhn, S E; Magahiz, R A; Major, R W; Martin, C; McGuckin, T; McNabb, J; Miskimen, R A; Müller, J A; Niczyporuk, B B; O'Meara, J E; Qin, L M; Raue, B A; Robb, J; Roudot, F; Schumacher, R A; Tedeschi, D J; Thompson, R A; Tilles, D; Tuzel, W; Vansyoc, K; Vineyard, M F; Weinstein, L B; Wilkin, G R; Yegneswaran, A; Yun, J

    2000-01-01

    Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on the toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

  7. Sentinel-1 provides ice drift observations for Copernicus Marine Environment Monitoring Service (CMEMS)

    DEFF Research Database (Denmark)

    Toudal Pedersen, Leif; Saldo, Roberto

    Sea ice drift information with an accuracy that allows also ice deformation (divergence, shear, vorticity) to be derived is being operationally generated in the Copernicus Marine Environment Monitoring Service (CMEMS).The method is based on 2-dimensional digital cross correlation where subsections...... are matched every month in the processing system.The quality of the ice drift vectors are routinely verified against GPS locations of drift buoys and the RMS difference between the baseline product available through the Copernicus Marine Environment Monitoring Service data portal and GPS drifters is ~500...

  8. Spatial-temporal assessment of climate model drifts

    Science.gov (United States)

    Zanchettin, Davide; Woldeyes Arisido, Maeregu; Gaetan, Carlo; Rubino, Angelo

    2016-04-01

    Decadal climate forecasts with full-field initialized coupled climate models are affected by a growing error signal that develops due to the adjustment of the simulations from the assimilated state consistent with observations to the state consistent with the biased model's climatology. Sea-surface temperature (SST) drifts and biases are a major concern due to the central role of SST properties for the dynamical coupling between the atmosphere and the ocean, and for the associated variability. Therefore, strong SST drifts complicate the initialization and assessment of decadal climate prediction experiments, and can be detrimental for their overall quality. We propose a dynamic linear model based on a state-space approach and developed within a Bayesian hierarchical framework for probabilistic assessment of spatial and temporal characteristics of SST drifts in ensemble climate simulations. The state-space approach uses unobservable state variables to directly model the processes generating the observed variability. The statistical model is based on a sequential definition of the process having a conditional dependency only on the previous time step, which therefore corresponds to the Kalman filter formulas. In our formulation, the statistical model distinguishes between seasonal and longer-term drift components, and between large-scale and local drifts. We apply the Bayesian method to make inferences on the variance components of the Gaussian errors in both the observation and system equations of the state-space model. To this purpose, we draw samples from their posterior distributions using a Monte Carlo Markov Chain simulation technique with a Gibbs sampler. In this contribution we illustrate a first application of the model using the MiKlip prototype system for decadal climate predictions. We focus on the tropical Atlantic Ocean - a region where climate models are typically affected by a severe warm SST bias - to demonstrate how our approach allows for a more

  9. Cryptoendolithic lichen and cyanobacterial communities of the Ross Desert, Antarctica

    Science.gov (United States)

    Friedmann, E. I.; Hua, M.; Ocampo-Friedmann, R.

    1988-01-01

    Cryptoendolithic microbial communities in the Ross Desert (McMurdo Dry Valleys) are characterized on the basis of photosynthetic microorganisms and fungi. Two eukaryotic communities (the lichen-dominated and Hemichloris communities) and three cyanobacterial communities (the red Gloeocapsa, Hormathonema-Gloeocapsa, and Chroococcidiopsis communities) are described. Eleven coccoid, one pleurocapsoid, and five filamentous cyanobacteria occurring in these communities are characterized and illustrated. The moisture grade of the rock substrate seems to affect pH, formation of primary iron stain, and the distribution of microbial communities.

  10. The Era of Newton, Herschel and Lord Rosse

    Science.gov (United States)

    Bennett, Jim

    2009-08-01

    In the eighteenth century England was dominant in building telescopes and instrumentation. This paper describes the contributions of the most important opticians and telescope builders, from Newton’s Opticks and the telescope design that bears his name, through various instrument makers who constructed ‘popular’ telescopes and published descriptions of mirror grinding (Smith, the Dollonds and their patent on achromatic lenses), to Herschel, who refined the description of his polishing procedures, and Lord Rosse, who attempted to communicate his through publication. The narrative of theory, practice and communication takes unexpected turns.

  11. Uma releitura da obra de Elisabeth Kubler-Ross

    OpenAIRE

    Afonso, Selene Bevil??qua Chaves; Minayo, Maria Cec??lia de Souza

    2013-01-01

    Este artigo apresenta uma releitura de parte da obra de Elizabeth Ross, uma das autoras mais citadas sobre a quest??o da terminalidade da vida, do luto e do morrer. Sua obra tem sido de grande contribui????o tanto para os profissionais de sa??de como para pais, m??es, filhos, parentes, leigos e religiosos que vivenciam o luto. Tamb??m tem sido alvo de controv??rsias relacionadas a quest??es ??ticas e quanto a seu rigor cient??fico. Os livros aqui comentados s??o: On...

  12. Jimmy, Sinclair, and Jim: on the biographical trail of James Sinclair Ross Jimmy, Sinclair, and Jim: on the biographical trail of James Sinclair Ross

    Directory of Open Access Journals (Sweden)

    John J. O'Connor

    2008-04-01

    Full Text Available The deaths of Earle Birney and Robertson Davies late in 1995 reminded readers of Canadian literature that the old order—those writers born before the First World War—was quickly passing. Of the major figures born in the early years of this century (Birney, Davies, Callaghan, MacLennan, Ross, only Ross was still living at the beginning of 1996, albeit in very poor health in a nursing home in Vancouver. The deaths of Earle Birney and Robertson Davies late in 1995 reminded readers of Canadian literature that the old order—those writers born before the First World War—was quickly passing. Of the major figures born in the early years of this century (Birney, Davies, Callaghan, MacLennan, Ross, only Ross was still living at the beginning of 1996, albeit in very poor health in a nursing home in Vancouver.

  13. 76 FR 55404 - Announcement of Funding Awards Resident Opportunity and Self-Sufficiency (ROSS)-Service...

    Science.gov (United States)

    2011-09-07

    ... URBAN DEVELOPMENT Announcement of Funding Awards Resident Opportunity and Self- Sufficiency (ROSS... Availability (NOFA) for the Resident Opportunity and Self-Sufficiency (ROSS)-Service Coordinators Program. This announcement contains the consolidated names and addresses of the award recipients for this year under the...

  14. 77 FR 30320 - General Management Plan/Environmental Impact Statement, Ross Lake National Recreation Area, North...

    Science.gov (United States)

    2012-05-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE INTERIOR National Park Service General Management Plan/Environmental Impact Statement, Ross Lake National Recreation... the Final Environmental Impact Statement for the new General Management Plan (GMP) for Ross...

  15. 75 FR 32802 - Certificate of Alternative Compliance for the Offshore Supply Vessel ROSS CANDIES

    Science.gov (United States)

    2010-06-09

    ... SECURITY Coast Guard Certificate of Alternative Compliance for the Offshore Supply Vessel ROSS CANDIES... Alternative Compliance was issued for the offshore supply vessel ROSS CANDIES as required by 33 U.S.C. 1605(c... Title 33, Code of Federal Regulation, part 81, has been issued for the offshore supply vessel...

  16. Giving to Excellence: Generating Philanthropic Support for UK Higher Education. Ross-CASE Report 2016

    Science.gov (United States)

    Jain, Yashraj

    2016-01-01

    This report presents findings from the 2016 Ross-CASE Survey of Philanthropic Giving to Universities in UK. The project was conducted by CASE Europe and funded by HEFCE and the Ross-Group. This year's survey comes at a time of great change for the UK charity sector. The historical trend data of previous surveys will be invaluable in helping…

  17. 75 FR 69432 - Ross Bachofer v. Calpine Corporation; Notice of Complaint

    Science.gov (United States)

    2010-11-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Ross Bachofer v. Calpine Corporation; Notice of Complaint November 4, 2010..., 18 CFR 385.206 and section 206 of the Federal Power Act, 16 U.S.C. 2824c, Ross Bachofer...

  18. Critiquing Research Methodology: Comments on Broader Concerns about Complex Statistical Studies. A Response to Ross

    Science.gov (United States)

    Stapleton, Paul

    2006-01-01

    Steven Ross's (2005) recent paper empirically measuring the efficacy of formative assessment compared to the summative variety found that the former produced positive effects on some aspects of language learning. In this critique, it is contended that Ross's study is flawed because his two groups of learners, one receiving summative assessment and…

  19. Against Raising Hope of Raising the Dead: Contra Moody and Kubler-Ross.

    Science.gov (United States)

    Vicchio, Stephen J.; And Others

    1979-01-01

    Kubler-Ross and Moody have made assertions about survival after death. They argued that the subjects were not dead, but in the process of dying. An alternative explanation to this "glimpse of the afterlife" approach is offered. Other theological objections are raised to the Moody/Kubler-Ross approach. (Author)

  20. Against Raising Hope of Raising the Dead: Contra Moody and Kubler-Ross.

    Science.gov (United States)

    Vicchio, Stephen J.; And Others

    1979-01-01

    Kubler-Ross and Moody have made assertions about survival after death. They argued that the subjects were not dead, but in the process of dying. An alternative explanation to this "glimpse of the afterlife" approach is offered. Other theological objections are raised to the Moody/Kubler-Ross approach. (Author)

  1. Approximate Stokes Drift Profiles and their use in Ocean Modelling

    Science.gov (United States)

    Breivik, Oyvind; Bidlot, Jea-Raymond; Janssen, Peter A. E. M.; Mogensen, Kristian

    2016-04-01

    Deep-water approximations to the Stokes drift velocity profile are explored as alternatives to the monochromatic profile. The alternative profiles investigated rely on the same two quantities required for the monochromatic profile, viz the Stokes transport and the surface Stokes drift velocity. Comparisons against parametric spectra and profiles under wave spectra from the ERA-Interim reanalysis and buoy observations reveal much better agreement than the monochromatic profile even for complex sea states. That the profiles give a closer match and a more correct shear has implications for ocean circulation models since the Coriolis-Stokes force depends on the magnitude and direction of the Stokes drift profile and Langmuir turbulence parameterizations depend sensitively on the shear of the profile. Of the two Stokes drift profiles explored here, the profile based on the Phillips spectrum is by far the best. In particular, the shear near the surface is almost identical to that influenced by the f-5 tail of spectral wave models. The NEMO general circulation ocean model was recently extended to incorporate the Stokes-Coriolis force along with two other wave-related effects. The ECWMF coupled atmosphere-wave-ocean ensemble forecast system now includes these wave effects in the ocean model component (NEMO).

  2. Shallow marine sedimentation within an active margin basin, James Ross Island, Antarctica

    Science.gov (United States)

    Pirrie, Duncan

    1989-06-01

    The Santa Marta Formation exposed on northern James Ross Island, Antarctica, represents shallow marine shelf sedimentation within an active margin basin. The formation is approximately 1000 m thick, is of uppermost Santonian to Campanian age and represents part of a 5000-6000 m thick sedimentary sequence forming the Larsen Basin. The Larsen Basin represents either a back-arc basin, or a half-graben basin, developed on the extending margin of the Weddell Sea. Twelve sedimentary facies have been recognised, which can be subdivided into two groups: those which are controlled by shelf processes and those which are related to active arc volcanism. Background shelf processes include fair-weather suspension sedimentation, storm sands and rare tidal current reworking. Active arc processes include direct settling of airfall detritus and rapid resedimentation of volcaniclastic detritus by sandy debris-flows and both high- and low-concentration turbidity currents. In addition sheet conglomerates represent debris flows that evolved from syn-sedimentary slumps. Two facies associations representing a mid to outer shelf and an inner shelf depositional setting respectively can be distinguished, with an apparent regression in the ?mid to late Campanian.

  3. 75 FR 31805 - Announcement of Funding Awards for the Resident Opportunity and Self-Sufficiency (ROSS)-Service...

    Science.gov (United States)

    2010-06-04

    ... URBAN DEVELOPMENT Announcement of Funding Awards for the Resident Opportunity and Self-Sufficiency (ROSS... Resident Opportunity and Self-Sufficiency (ROSS) Service Coordinators Program funding for Fiscal Year 2009... questions concerning the FY 2009 Resident Opportunity and Self-Sufficiency (ROSS) Service...

  4. Dispersal of invasive species by drifting

    NARCIS (Netherlands)

    Riel, van M.C.; Velde, van der G.; Vaate, bij de A.

    2011-01-01

    Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of

  5. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez laso, L.

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  6. Processes influencing formation of low-salinity high-biomass lenses near the edge of the Ross Ice Shelf

    Science.gov (United States)

    Li, Yizhen; McGillicuddy, Dennis J.; Dinniman, Michael S.; Klinck, John M.

    2017-02-01

    Both remotely sensed and in situ observations in austral summer of early 2012 in the Ross Sea suggest the presence of cold, low-salinity, and high-biomass eddies along the edge of the Ross Ice Shelf (RIS). Satellite measurements include sea surface temperature and ocean color, and shipboard data sets include hydrographic profiles, towed instrumentation, and underway acoustic Doppler current profilers. Idealized model simulations are utilized to examine the processes responsible for ice shelf eddy formation. 3-D model simulations produce similar cold and fresh eddies, although the simulated vertical lenses are quantitatively thinner than observed. Model sensitivity tests show that both basal melting underneath the ice shelf and irregularity of the ice shelf edge facilitate generation of cold and fresh eddies. 2-D model simulations further suggest that both basal melting and downwelling-favorable winds play crucial roles in forming a thick layer of low-salinity water observed along the edge of the RIS. These properties may have been entrained into the observed eddies, whereas that entrainment process was not captured in the specific eddy formation events studied in our 3-D model-which may explain the discrepancy between the simulated and observed eddies, at least in part. Additional sensitivity experiments imply that uncertainties associated with background stratification and wind stress may also explain why the model underestimates the thickness of the low-salinity lens in the eddy interiors. Our study highlights the importance of incorporating accurate wind forcing, basal melting, and ice shelf irregularity for simulating eddy formation near the RIS edge. The processes responsible for generating the high phytoplankton biomass inside these eddies remain to be elucidated.

  7. A Stokes drift approximation based on the Phillips spectrum

    CERN Document Server

    Breivik, Øyvind; Janssen, Peter A E M

    2016-01-01

    A new approximation to the Stokes drift velocity pro?le based on the exact solution for the Phillips spectrum is explored. The pro?file is compared with the monochromatic pro?file and the recently proposed exponential integral profi?le. ERA-Interim spectra and spectra from a wave buoy in the central North Sea are used to investigate the behaviour of the profi?le. It is found that the new profi?le has a much stronger gradient near the surface and lower normalized deviation from the pro?le computed from the spectra. Based on estimates from two open-ocean locations, an average value has been estimated for a key parameter of the profi?le. Given this parameter, the profi?le can be computed from the same two parameters as the monochromatic profi?le, namely the transport and the surface Stokes drift velocity.

  8. Nonlinear evolution of drift instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.W.; Krommes, J.A.; Oberman, C.R.; Smith, R.A.

    1984-01-01

    The nonlinear evolution of collisionless drift instabilities in a shear-free magnetic field has been studied by means of gyrokinetic particle simulation as well as numerical integration of model mode-coupling equations. The purpose of the investigation is to identify relevant nonlinear mechanisms responsible for the steady-state drift wave fluctuations. It is found that the saturation of the instability is mainly caused by the nonlinear E x B convection of the resonant electrons and their associated velocity space nonlinearity. The latter also induces energy exchange between the competing modes, which, in turn, gives rise to enhanced diffusion. The nonlinear E x B convection of the ions, which contributes to the nonlinear frequency shift, is also an important ingredient for the saturation.

  9. A Pascalian lateral drift sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, H., E-mail: hendrik.jansen@desy.de

    2016-09-21

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  10. A Pascalian lateral drift sensor

    Science.gov (United States)

    Jansen, H.

    2016-09-01

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  11. MPS II drift chamber system

    Energy Technology Data Exchange (ETDEWEB)

    Platner, E.D.

    1982-01-01

    The MPS II detectors are narrow drift space chambers designed for high position resolution in a magnetic field and in a very high particle flux environment. Central to this implementation was the development of 3 multi-channel custom IC's and one multi-channel hybrid. The system is deadtimeless and requires no corrections on an anode-to-anode basis. Operational experience and relevance to ISABELLE detectors is discussed.

  12. Antarctic sea ice variability and trends, 1979–2010

    Directory of Open Access Journals (Sweden)

    D. J. Cavalieri

    2012-08-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has (like the Arctic instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but the magnitudes of the two trends differ, and in some cases these differences allow inferences about the corresponding changes in sea ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  13. Shear wall ultimate drift limits

    Energy Technology Data Exchange (ETDEWEB)

    Duffey, T.A. [Duffy, (T.A.) Tijeras, NM (United States); Goldman, A. [Goldman, (A.), Sandia, Los Alamos, NM (United States); Farrar, C.R. [Los Alamos National Lab., NM (United States)

    1994-04-01

    Drift limits for reinforced-concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Drift values at ultimate are determined for walls with aspect ratios ranging up to a maximum of 3.53 and undergoing different types of lateral loading (cyclic static, monotonic static, and dynamic). Based on the geometry of actual nuclear power plant structures exclusive of containments and concerns regarding their response during seismic (i.e.,cyclic) loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which testing is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information. The statistical nature of the data is also investigated. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of statistics to estimate Probability of Failure for a shear wall structure is illustrated.

  14. Coccolithophores from the central Arabian Sea: Sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L.P.; Mohan, R.; Murty, V.S.N.; Guptha, M.V.S.; Sinha, D.K.

    in this region and result in the variability of coccolithophores as recorded in the sediment trap samples at greater depth. Maps of satellite derived Sea Surface Temperature (SST) and blended from buoys (moored and drift- ing) data, for the study period (November... of monthly mean satellite derived Sea Surface Temperature (SST) and blended from buoys (mooring and drifting) data in the Arabian Sea during (a) November 1993, (b) January 1994, (c) May 1994 and (d) July 1994. The sediment trap location is depicted...

  15. Dispersal of invasive species by drifting

    Directory of Open Access Journals (Sweden)

    M.C. VAN RIEL, G. VAN DER VELDE, A. BIJ DE VAATE

    2011-12-01

    Full Text Available Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium curvispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a dispersal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range [Current Zoology 57 (6: 818–827, 2011].

  16. Gaussian estimation for discretely observed Cox-Ingersoll-Ross model

    Science.gov (United States)

    Wei, Chao; Shu, Huisheng; Liu, Yurong

    2016-07-01

    This paper is concerned with the parameter estimation problem for Cox-Ingersoll-Ross model based on discrete observation. First, a new discretized process is built based on the Euler-Maruyama scheme. Then, the parameter estimators are obtained by employing the maximum likelihood method and the explicit expressions of the error of estimation are given. Subsequently, the consistency property of all parameter estimators are proved by applying the law of large numbers for martingales, Holder's inequality, B-D-G inequality and Cauchy-Schwarz inequality. Finally, a numerical simulation example for estimators and the absolute error between estimators and true values is presented to demonstrate the effectiveness of the estimation approach used in this paper.

  17. [A reappraisal of the works of Elisabeth Kubler-Ross].

    Science.gov (United States)

    Afonso, Selene Beviláqua Chaves; Minayo, Maria Cecília de Souza

    2013-09-01

    This article presents a reappraisal of part of the works of Elizabeth Kubler-Ross, one of the most quoted authors addressing the end of life process, mourning and dying. Her work has contributed to a clearer understanding of these issues by health professionals, families, religious and lay people who handle and/or experience mourning. She has also been the subject of controversy related to ethical issues and the scientific rigor of her work. The books analyzed in this article are: On death and dying (1969); Questions and answers on death and dying (1971); Living with death and dying (1981); On children and death(1983); On life after death (1991) and Life lessons (2000).

  18. Uma releitura da obra de Elisabeth Kubler-Ross

    OpenAIRE

    Selene Beviláqua Chaves Afonso; Maria Cecília de Souza Minayo

    2013-01-01

    Este artigo apresenta uma releitura de parte da obra de Elizabeth Ross, uma das autoras mais citadas sobre a questão da terminalidade da vida, do luto e do morrer. Sua obra tem sido de grande contribuição tanto para os profissionais de saúde como para pais, mães, filhos, parentes, leigos e religiosos que vivenciam o luto. Também tem sido alvo de controvérsias relacionadas a questões éticas e quanto a seu rigor científico. Os livros aqui comentados são: On death and dying (Sobre A morte e o mo...

  19. Antarctic Sea Ice Variability and Trends, 1979-2010

    Science.gov (United States)

    Parkinson, C. L.; Cavalieri, D. J.

    2012-01-01

    In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978 - December 2010 reveal an overall positive trend in ice extents of 17,100 +/- 2,300 square km/yr. Much of the increase, at 13,700 +/- 1,500 square km/yr, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of -8,200 +/- 1,200 square km/yr. When examined through the annual cycle over the 32-year period 1979-2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9,100 +/- 6,300 square km/yr in February to a high of 24,700 +/- 10,000 square km/yr in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  20. Antarctic sea ice variability and trends, 1979–2010

    Directory of Open Access Journals (Sweden)

    D. J. Cavalieri

    2012-03-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  1. A drifting trajectory prediction model based on object shape and stochastic mo-tion features

    Institute of Scientific and Technical Information of China (English)

    王胜正; 聂皓冰; 施朝健

    2014-01-01

    There is a huge demand to develop a method for marine search and rescue (SAR) operators automatically predicting the most probable searching area of the drifting object. This paper presents a novel drifting prediction model to improve the accuracy of the drifting trajectory computation of the sea-surface objects. First, a new drifting kinetic model based on the geometry characteristics of the objects is proposed that involves the effects of the object shape and stochastic motion features in addition to the traditional factors of wind and currents. Then, a computer simulation-based method is employed to analyze the stochastic motion features of the drifting objects, which is applied to estimate the uncertainty parameters of the stochastic factors of the drifting objects. Finally, the accuracy of the model is evaluated by comparison with the flume experimental results. It is shown that the proposed method can be used for various shape objects in the drifting trajectory prediction and the maritime search and rescue decision-making system.

  2. A case of Ross syndrome presented with Horner and chronic cough

    Directory of Open Access Journals (Sweden)

    Aslihan Baran

    2014-01-01

    Full Text Available Ross syndrome is a rare sweating disorder associated with Adie′s tonic pupil, decreased or diminished tendon reflex and unknown etiology. Although autonomic disturbances affecting sudomotor and vasomotor functions are seen commonly, they are rarely symptomatic. While Ross syndrome is typically characterized with dilated tonic pupil, it may be rarely manifested with miotic pupils (little old Adie′s pupil, which can make diagnosis difficult. In this article, we aim to specify the atypical clinical manifestations of syndrome by means of Ross syndrome manifested by autonomic symptoms, Horner syndrome, chronic cough together with bilateral little old Adie′s pupil.

  3. Stochastic modeling for trajectories drift in the ocean: Application of Density Clustering Algorithm

    CERN Document Server

    Shchekinova, E Y

    2015-01-01

    The aim of this study is to address the effects of wind-induced drift on a floating sea objects using high--resolution ocean forecast data and atmospheric data. Two applications of stochastic Leeway model for prediction of trajectories drift in the Mediterranean sea are presented: long-term simulation of sea drifters in the western Adriatic sea (21.06.2009-23.06.2009) and numerical reconstruction of the Elba accident (21.06.2009-23.06.2009). Long-term simulations in the western Adriatic sea are performed using wind data from the European Center for Medium-Range Weather Forecast (ECMWF) and currents from the Adriatic Forecasting System (AFS). An algorithm of spatial clustering is proposed to identify the most probable search areas with a high density of drifters. The results are compared for different simulation scenarios using different categories of drifters and forcing fields. The reconstruction of sea object drift near to the Elba Island is performed using surface currents from the Mediterranean Forecastin...

  4. Spiral biasing adaptor for use in Si drift detectors and Si drift detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zheng; Chen, Wei

    2016-07-05

    A drift detector array, preferably a silicon drift detector (SDD) array, that uses a low current biasing adaptor is disclosed. The biasing adaptor is customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front side and back side of the detector array.

  5. Geology and geomorphology--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included in...

  6. NIST Computer Scientist and Researcher Dr. Ron Ross Discusses Cybersecurity During Latest SGL

    OpenAIRE

    2010-01-01

    National Institute of Standards and Technology (NIST) senior computer scientist and information security researcher Dr. Ron Ross presented a lecture to students, staff and faculty on the new challenges in cybersecurity.

  7. In memoriam: Mr Donald Nixon Ross 4 October 1922 to 7 July 2014 (91 years).

    Science.gov (United States)

    Yankah, Charles

    2014-01-01

    We are deeply saddened by the loss of our great teacher Donald Ross, a truly global mentor in cardiac surgery, a friend, a respectful colleague, an admirer, and custodian of our profession, who passed away on July 7, 2014.

  8. Geology and geomorphology--Offshore of Fort Ross Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the geologic and geomorphic map of the Offshore of Fort Ross map area, California. The vector data file is included in...

  9. Parcels and Land Ownership, Published in unknown, Ross County Soil and Water Conservation District (SWCD).

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Parcels and Land Ownership dataset as of unknown. The extent of these data is generally Ross County, OH. This metadata was auto-generated through the Ramona GIS...

  10. Elisabeth Kubler-Ross and the Tradition of the Private Sphere: An Analysis of Symbols.

    Science.gov (United States)

    Klass, Dennis

    1981-01-01

    Shows how Kubler-Ross' schema functions as a symbol system. Analyzes the symbol "acceptance." Shows how that symbol is part of a strong American tradition of symbols of the private sphere. (Author/JAC)

  11. Limits to Drift Chamber Resolution

    CERN Document Server

    Riegler, Werner

    1998-01-01

    ATLAS (A Large Toroidal LHC Apparatus) will be a general-purpose experiment at the Large Hadron Collider that will be operational at CERN in the year 2004. The ATLAS muon spectrometer aims for a momentum resolution of 10% for a transverse momentum of pT=1TeV. The precision tracking devices in the muon system will be high pressure drift tubes (MDTs) with a single wire resolution of 1100 chambers covering an area of ≈ 2500m2. The high counting rates in the spectrometer as well as the aim for excellent spatial resolution and high efficiency put severe constraints on the MDT operating parameters. This work describes a detailed study of all the resolution limiting factors in the ATLAS environment. A ’full chain’ simulation of the MDT response to photons and charged particles as well as quantitative comparisons with measurements was performed. The good agreement between simulation and measurements resulted in a profound understanding of the drift chamber processes and the individual contributions to the spat...

  12. O ecocardiograma transesofágico na cirurgia de Ross

    Directory of Open Access Journals (Sweden)

    Marcello Fonseca Salgado Filho

    2011-06-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: Uma das cirurgias corretivas para a insuficiência aórtica congênita grave é a cirurgia de Ross. O ecocardiograma transesofágico intraoperatório é indispensável para uma boa avaliação cirúrgica. Além disso, é capaz de avaliar o perfil volêmico e a necessidade de se administrar drogas vasoativas ao longo da cirurgia. RELATO DO CASO: Adolescente de 15 anos apresentava insuficiência aórtica grave de origem congênita, programando-se correção cirúrgica pela técnica de Ross. No centro cirúrgico, o paciente foi monitorado com eletrocardiograma e oxímetro de pulso, recebendo pré-medicação com midazolam. Após a pré-medicação, puncionaram-se a artéria radial esquerda e a veia subclávia direita. A indução anestésica foi feita com etomidato, cisatracúrio e fentanil, e a manutenção anestésica com sevoflurano. A sonda do aparelho do ecocardiograma transesofágico foi introduzida imediatamente após a intubação traqueal e mostrava aumento do ventrículo esquerdo; insuficiência aórtica grave por falha de coaptação dos três folhetos; válvula pulmonar competente sem alterações anatômicas e fisiológicas. A cirurgia transcorreu sem intercorrências, com 120 minutos de circulação extracorpórea (CEC e 8 horas de cirurgia. Imediatamente após a saída de CEC, o ecocardiograma transesofágico mostrava bom funcionamento tanto do auto como do homoenxerto, porém o ventrículo direito encontrava-se hipocontrátil, o que foi corrigido com bolus de milrinona, seguido de infusão contínua. O paciente foi encaminhado ao pós-operatório intubado, estável hemodinamicamente, com infusão de milrinona e nitroprussiato de sódio. CONCLUSÕES: Uma das técnicas de correção da insuficiência aórtica congênita é a cirurgia de Ross, em que o ecocardiograma transesofágico intraoperatório orienta o cirurgião de maneira precisa sobre o status fisiológico e anatômico dos enxertos vasculares.

  13. Frank Ross's Early Direct Photographs of Venus and His Interpretation of Them

    Science.gov (United States)

    Osterbrock, Donald E.

    2006-09-01

    Frank Ross was an outstandingly creative astronomical "jack of many trades" (Monet) or "cat with nine astronomical lives". After joining the Yerkes Observatory faculty in 1924, at age 50, he took a long series of almost nightly direct photographs of Venus in 1927 with the Mount Wilson 60-inch and 100-inch reflectors as a guest observer. He published many of these images in the ApJ in 1928, with his conclusions on the nature of Venus. Ross discovered markings, seen only in the ultraviolet images, parallel "belts" indicating rotation. They changed rapidly. From these photographs he developed a tentative picture of a deep opaque atmosphere, with high pressure at the surface of the planet. The changes were due to "violent events" (winds or storms) in its atmosphere. From spectroscopic results of Slipher, Adams, StJohn, and Nicholson he took the rotation period to be long. But bolometric observations of Pettit, Nicholson, Coblentz, and Lampland, indicated little temperature change between the illuminated and dark parts of the disk, so it could not be too slow. Ross settled on a "compromise" rotation period of about 30 days based on the data he had. The spectroscopic measurements showed there was very little, if any, H2O or O2 in the atmosphere. Ross is best known today for his Ross wide-angle camera design, his Ross high-proper-motion stars, his Ross photometer, and his Ross correctors for large reflecting telescopes, but his foray into planetary astronomy, long before the era of radar or close-up imaging and spectroscopy from space vehicles, was an important first step toward understanding Venus. His years of experience in laboratory studies of the properties of photographic plates, developers, and mensuration were highly important for this work. Equally so were his cheerful, peppery personality and his close relations with many Mount Wilson and Lowell Observatory staff members.

  14. Donald Nixon Ross, BS, MB, ChB, FRCS: pioneering surgeon and true gentleman.

    Science.gov (United States)

    Chitwood, W Randolph

    2015-03-01

    Donald Nixon Ross, FRCS, was a master surgeon, a consummate scholar, and fine gentleman. Herein, are descriptions of his education, practice of cardiac surgery, and legacy contributions. He always will be known for developing and applying the aortic autograft "switch" procedure for aortic stenosis known in perpetuity as the Ross procedure. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  15. Drift chamber tracking with neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Lindsey, C.S.; Denby, B.; Haggerty, H.

    1992-10-01

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed.

  16. Snow Drift Management: Summit Station Greenland

    Science.gov (United States)

    2016-05-01

    ER D C/ CR RE L TR -1 6- 6 Engineering for Polar Operations, Logistics, and Research (EPOLAR) Snow Drift Management Summit Station...Drift Management Summit Station Greenland Robert B. Haehnel and Matthew F. Bigl U.S. Army Engineer Research and Development Center (ERDC) Cold...Engineering for Polar Operations, Logistics, and Research (EPOLAR) EP-ARC-15-33, “Monitoring and Managing Snow Drifting at Summit Station, Greenland” ERDC

  17. Landscapes of the Self: The Cinema of Ross McElwee / Paisajes del yo. El cine de Ross McElwee

    OpenAIRE

    E. Cuevas; García-Martínez, A.N. (Alejandro Néstor)

    2008-01-01

    Monografía sobre el documentalista Ross McElwee. Incluye 9 capítulos que estudian su obra, un texto suyo y una entrevista. El libro está en inglés y castellano. Este enlace incluye sólo el índice y la introducción A monography about the films of American documentary filmmaker Ross McElwee. It includes 9 chapters about his work, one text written by him, and an interview. The book is in English and Spanish. This link includes only the Table of Contents and the Introduction.

  18. The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC)

    Science.gov (United States)

    Sommerfeld, Anja; Rex, Markus; Shupe, Matthew; Dethloff, Klaus

    2017-04-01

    The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) is an international initiative under the umbrella of the International Arctic Science Committee (IASC) designed by an international consortium of leading polar research institutes. Rapid changes in the Arctic lead to an urgent need for reliable information about the state and evolution of the Arctic climate system. This requires more observations and improved modelling over various spatial and temporal scales, and across a wide variety of disciplines. MOSAiC will be the first year-around expedition into the central Arctic exploring the coupled climate system. The research vessel Polarstern will drift with the sea ice across the central Arctic during the years 2019 to 2020. The drift starts in the Siberian sector of the Arctic in thin sea ice conditions in late summer. A distributed regional network of observational sites will be established on the sea ice in an area of up to 50 km distance from Polarstern, representing a grid cell of climate models. The ship and the surrounding network will drift with the natural sea ice drift across the polar cap towards the Atlantic, while the sea ice thickens during the winter. The focus of MOSAiC lies on in-situ observations of the climate processes that couple atmosphere, ocean, sea ice, bio-geochemistry and ecosystem. These measurements will be supported by weather and sea ice predictions and remote sensing operations to make the expedition successful. The expedition includes aircraft operations and cruises by icebreakers from MOSAiC partners. All these observations will be used for the main scientific goals of MOSAiC, enhancing the understanding of the regional consequences of Arctic climate change and sea ice loss and improve weather forecast and climate models. More precisely, the results are needed to advance the data assimilation for numerical weather prediction models, sea ice forecasts and climate models and ground truth for satellite

  19. Redshift drift in a pressure gradient cosmology

    CERN Document Server

    Balcerzak, Adam

    2012-01-01

    We derive the redshift drift formula for the inhomogeneous pressure spherically symmetric Stephani universes which are complementary to inhomogeneous density Lema\\^itre-Tolman-Bondi (LTB) models. We show that there is a clear difference between the redshift drift predictions for these two models. The Stephani models have positive drift values at small redshift and behave qualitatively as the $\\Lambda$CDM models while the drift for LTB models is always negative. This prediction can be tested in future space experiments such as E-ELT, TMT, GMT or CODEX.

  20. THERMAL EVALUATION OF DIFFERENT DRIFT DIAMETER SIZES

    Energy Technology Data Exchange (ETDEWEB)

    H.M. Wade

    1999-01-04

    The purpose of this calculation is to estimate the thermal response of a repository-emplaced waste package and its corresponding drift wall surface temperature with different drift diameters. The case examined is that of a 21 pressurized water reactor (PWR) uncanistered fuel (UCF) waste package loaded with design basis spent nuclear fuel assemblies. This calculation evaluates a 3.5 meter to 6.5 meter drift diameter range in increments of 1.0 meters. The time-dependent temperatures of interest, as determined by this calculation, are the spent nuclear fuel cladding temperature, the waste package surface temperature, and the drift wall surface temperature.

  1. RF Breakdown in Drift Tube Linacs

    CERN Document Server

    Stovall, J; Lown, R

    2009-01-01

    The highest RF electric field in drift-tube linacs (DTLs) often occurs on the face of the first drift tube. Typically this drift tube contains a quadrupole focusing magnet whose fringing fields penetrate the face of the drift tube parallel to the RF electric fields in the accelerating gap. It has been shown that the threshold for RF breakdown in RF cavities may be reduced in the presence of a static magnetic field. This note offers a “rule of thumb” for picking the maximum “safe” surface electric field in DTLs based on these measurements.

  2. Ross, macdonald, and a theory for the dynamics and control of mosquito-transmitted pathogens.

    Science.gov (United States)

    Smith, David L; Battle, Katherine E; Hay, Simon I; Barker, Christopher M; Scott, Thomas W; McKenzie, F Ellis

    2012-01-01

    Ronald Ross and George Macdonald are credited with developing a mathematical model of mosquito-borne pathogen transmission. A systematic historical review suggests that several mathematicians and scientists contributed to development of the Ross-Macdonald model over a period of 70 years. Ross developed two different mathematical models, Macdonald a third, and various "Ross-Macdonald" mathematical models exist. Ross-Macdonald models are best defined by a consensus set of assumptions. The mathematical model is just one part of a theory for the dynamics and control of mosquito-transmitted pathogens that also includes epidemiological and entomological concepts and metrics for measuring transmission. All the basic elements of the theory had fallen into place by the end of the Global Malaria Eradication Programme (GMEP, 1955-1969) with the concept of vectorial capacity, methods for measuring key components of transmission by mosquitoes, and a quantitative theory of vector control. The Ross-Macdonald theory has since played a central role in development of research on mosquito-borne pathogen transmission and the development of strategies for mosquito-borne disease prevention.

  3. Quantifying fall migration of Ross's gulls (Rhodostethia rosea) past Point Barrow, Alaska

    Science.gov (United States)

    Uher-Koch, Brian D.; Davis, Shanti E.; Maftei, Mark; Gesmundo, Callie; Suydam, R.S.; Mallory, Mark L.

    2014-01-01

    The Ross's gull (Rhodostethia rosea) is a poorly known seabird of the circumpolar Arctic. The only place in the world where Ross's gulls are known to congregate is in the near-shore waters around Point Barrow, Alaska where they undertake an annual passage in late fall. Ross's gulls seen at Point Barrow are presumed to originate from nesting colonies in Siberia, but neither their origin nor their destination has been confirmed. Current estimates of the global population of Ross's gulls are based largely on expert opinion, and the only reliable population estimate is derived from extrapolations from previous counts conducted at Point Barrow, but these data are now over 25 years old. In order to update and clarify the status of this species in Alaska, our study quantified the timing, number, and flight direction of Ross's gulls passing Point Barrow in 2011. We recorded up to two-thirds of the estimated global population of Ross's gulls (≥ 27,000 individuals) over 39 days with numbers peaking on 16 October when we observed over 7,000 birds during a three-hour period.

  4. Fermilab drift tube Linac revisited

    Energy Technology Data Exchange (ETDEWEB)

    Milorad Popovic

    2004-05-12

    Using the PARMILA code running under PC-WINDOWS, the present performance of the Fermilab Drift Tube Linac has been analyzed in the light of new demands on the Linac/Booster complex (the Proton Source). The Fermilab Drift Tube Linac (DTL) was designed in the sixties as a proton linac with a final energy of 200 MeV and a peak current of 100mA. In the seventies, in order to enable multi-turn charge exchange injection into the Booster, the ion source was replaced by an H- source with a peak beam current of 25mA. Since then the peak beam current was steadily increased up to 55mA. In the early nineties, part of the drift tube structure was replaced with a side-coupled cavity structure in order to increase the final energy to 400 MeV. The original and still primary purpose of the linac is to serve as the injector for the Booster. As an added benefit, the Neutron Therapy Facility (NTF) was built in the middle seventies. It uses 66MeV protons from the Linac to produce neutrons for medical purposes. The Linac/Booster complex was designed to run at a fundamental cycling rate of 15Hz, but beam is accelerated on every cycle only when NTF is running. Until recently the demand from the High Energy Physics program resulted in an average linac beam repetition rate of order 1 Hz. With the MiniBoone experiment and the NuMI program, the demands on the Proton Source have changed, with emphasis on higher beam repetition rates up to 7.5Hz. Historically the beam losses in the linac were small, localized at one spot, so activation was not an important issue. With higher beam rate, this has the potential to become the dominant issue. Until today all tuning in the linac and Proton Source was governed by two goals: to maximize the peak beam current out of the linac and to minimize the beam losses in the linac. If maximal peak current from the linac is no longer a primary goal, then the linac quadrupoles can be adjusted differently to achieve different goals.

  5. Confirming and Improving Ross Variable Star RV Del

    Science.gov (United States)

    Linder, Tyler R.; Sanchez, Rick; Palser, Sage; Schultze, Kendra; Kenney, Jessica; Thompson, Briana; DeCoster, Richard; Mills, Frank; Osborn, Wayne; Hoette, Vivian L.; Skynet Junior Scholars; Stone Edge Observatory

    2017-01-01

    RV Del is an intrinsic pulsating variable star in the constellation Delphinus, discovered by Ross (1926). The AAVSO list RV Del as a RRAB type of variable star. RV Del has been found to have a magnitude that varies from 12.9 - 14.2 and a period of 11.9553 hours.The purpose of our research of RV Del is to confirm and improve previous results as well as explore different methods to engage middle school students in the scientific method and astronomy. The SKYNET network of telescopes allows students to request images from a group of international research class telescopes. The telescope request process allows students first-hand experience in astronomy while the data analysis allows students to understand advance software systems to produce publishable results. Data is being gathered using the SKYNET network and Stone Edge Observatory to gather photometry of RV Del and create a new light curve. Findings will be presented the January 2017 AAS.

  6. Ghost Stories: Review of Ross Gibson's The Summer Exercises

    Directory of Open Access Journals (Sweden)

    Deane Williams

    2010-03-01

    Full Text Available Back 
in 
1986, 
Ross 
Gibson
 was 
interviewed 
in
 Filmnews 
by
 Adrian
 Martin 
and
Tina
 Kaufman
 about
 his
 experimental
 short
 essay
 film
 Camera
 Natura
 (1984. Accompanying
 that
 interview
 was
 a
 photo
 of
 Gibson
 ‘on
 location’
 for
 his
 film,
 wearing
 a
 hat
 not
 unlike
 the
 one
 that
 features
 on
 the
 cover
 of
 his
 new
 book
 The
 Summer 
Exercises.
 Back 
then
 I
 understood
 the 
hat
 to 
be
 an
explorer’s,
 someone 
like
 Charles
 Sturt,
 someone
 whose
 willingness
 to
 learn
 from
 his
 environment
 had
 impressed
 Gibson
 in
 fashioning
 his
 own
 history
 of
 Australian
 landscape
 imaging.
 Now
 the
 hat
 looks
 like
 a
 detective’s
 or,
 rather,
 Marcel
 Duchamp’s
 rendering
 of
 a
 detective’s
 hat: 
on 
display,
 ready 
for
 our
 re‐consideration.

  7. Uma releitura da obra de Elisabeth Kubler-Ross

    Directory of Open Access Journals (Sweden)

    Selene Beviláqua Chaves Afonso

    2013-09-01

    Full Text Available Este artigo apresenta uma releitura de parte da obra de Elizabeth Ross, uma das autoras mais citadas sobre a questão da terminalidade da vida, do luto e do morrer. Sua obra tem sido de grande contribuição tanto para os profissionais de saúde como para pais, mães, filhos, parentes, leigos e religiosos que vivenciam o luto. Também tem sido alvo de controvérsias relacionadas a questões éticas e quanto a seu rigor científico. Os livros aqui comentados são: On death and dying (Sobre A morte e o morrer, de 1969; Questions and answers on death and dying (Perguntas e respostas sobre a morte e o morrer, de 1971; Living with death and dying(Vivendo com a morte e os moribundos, de 1981; On children and death (Sobre as crianças e a morte, de 1983; On life after death (Sobre a vida depois da morte, de 1991 e Life lessons (Lições de vida, de 2000.

  8. Silicon drift detectors with the drift field induced by pureB-coated trenches

    NARCIS (Netherlands)

    Nanver, Lis Karen; Kneževi´c, Tihomir; Suligoj, Tomislav

    2016-01-01

    Junction formation in deep trenches is proposed as a new means of creating a built-in drift field in silicon drift detectors (SDDs). The potential performance of this trenched drift detector (TDD) was investigated analytically and through simulations, and compared to simulations of conventional

  9. The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift

    Science.gov (United States)

    Price, Rebecca M.; Andrews, Tessa C.; McElhinny, Teresa L.; Mead, Louise S.; Abraham, Joel K.; Thanukos, Anna; Perez, Kathryn E.

    2014-01-01

    Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures…

  10. Autoresonant control of drift waves

    Science.gov (United States)

    Shagalov, A. G.; Rasmussen, J. Juul; Naulin, V.

    2017-03-01

    The control of nonlinear drift waves in a magnetized plasmas column has been investigated. The studies are based on the Hasegawa–Mima model, which is solved on a disk domain with radial inhomogeneity of the plasma density. The system is forced by a rotating potential with varying frequency defined on the boundary. To excite and control the waves we apply the autoresonant effect, taking place when the amplitude of the forcing exceeds a threshold value and the waves are phase-locked with the forcing. We demonstrate that the autoresonant approach is applicable for excitation of a range of steady nonlinear waves of the lowest azimuthal mode numbers and for controlling their amplitudes and phases. We also demonstrate the excitation of zonal flows (m = 0 modes), which are controlled via the forced modes.

  11. Autoresonant control of drift waves

    DEFF Research Database (Denmark)

    Shagalov, A.G.; Rasmussen, Jens Juul; Naulin, Volker

    2017-01-01

    The control of nonlinear drift waves in a magnetized plasmas column has been investigated. The studies are based on the Hasegawa–Mima model, which is solved on a disk domain with radial inhomogeneity of the plasma density. The system is forced by a rotating potential with varying frequency defined...... on the boundary. To excite and control the waves we apply the autoresonant effect, taking place when the amplitude of the forcing exceeds a threshold value and the waves are phase-locked with the forcing. We demonstrate that the autoresonant approach is applicable for excitation of a range of steady nonlinear...... waves of the lowest azimuthal mode numbers and for controlling their amplitudes and phases. We also demonstrate the excitation of zonal flows (m = 0 modes), which are controlled via the forced modes....

  12. The ARGUS microvertex drift chamber

    Science.gov (United States)

    Michel, E.; Schmidt-Parzefall, W.; Appuhn, R. D.; Buchmüller, J.; Kolanoski, H.; Kreimeier, B.; Lange, A.; Siegmund, T.; Walther, A.; Edwards, K. W.; Fernholz, R. C.; Kapitza, H.; MacFarlane, D. B.; O'Neill, M.; Parsons, J. A.; Prentice, J. D.; Seidel, S. C.; Tsipolitis, G.; Ball, S.; Babaev, A.; Danilov, M.; Tichomirov, I.

    1989-11-01

    The ARGUS collaboration is currently building a new microvertex drift chamber (μVDC) as an upgrade of their detector. The μVDC is optimized for B-meson physics at DORIS energies. Important design features are minimal multiple scattering for low-momentum particles and three-dimensional reconstruction of decay vertices with equal resolutions in r- φ and r- z. Vertex resolutions of 15-25 μm are expected. Prototypes of the μVDC have been tested with different gas mixtures at various pressures. Spatial resolutions as small as 20 μm were obtained using CO 2/propane at 4 bar and DME at 1 bar. New readout electronics have been developed for the μVDC aiming at low thresholds for the TDC measurements. Employing a novel idea for noise and cross-talk suppression, which is based on a discrimination against short pulses, very low threshold settings are possible.

  13. Exploring Arctic Transpolar Drift During Dramatic Sea Ice Retreat

    DEFF Research Database (Denmark)

    Gascard, J.C.; Festy, J.; le Goff, H.

    2008-01-01

    The Arctic is undergoing significant environmental changes due to climate warming. The most evident signal of this warming is the shrinking and thinning of the ice cover of the Arctic Ocean. If the warming continues, as global climate models predict, the Arctic Ocean will change from a perennially...

  14. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    Samiran Ghosh; Nikhil Chakrabarti; Manoranjan Khan; M R Gupta

    2013-02-01

    The conditions for the existence of low-frequency electrostatic drift wave in pair-ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  15. Resistive Drift Waves in a Bumpy Torus

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2004-01-12

    A computational study of resistive drift waves in the edge plasma of a bumpy torus is presented. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.

  16. Biology Undergraduates' Misconceptions about Genetic Drift

    Science.gov (United States)

    Andrews, T. M.; Price, R. M.; Mead, L. S.; McElhinny, T. L.; Thanukos, A.; Perez, K. E.; Herreid, C. F.; Terry, D. R.; Lemons, P. P.

    2012-01-01

    This study explores biology undergraduates' misconceptions about genetic drift. We use qualitative and quantitative methods to describe students' definitions, identify common misconceptions, and examine differences before and after instruction on genetic drift. We identify and describe five overarching categories that include 16 distinct…

  17. Do Arctic waders use adaptive wind drift?

    NARCIS (Netherlands)

    Green, M; Alerstam, T; Gudmundsson, GA; Hedenstrom, A; Piersma, T; Gudmundsson, Gudmundur A.; Hedenström, Anders

    2004-01-01

    We analysed five data sets of night directions of migrating arctic waders ill relation to,winds, recorded by tracking radar and optical range finder, in order to find out if these birds compensate for wind drift, or allow themselves to be drifted by winds. Our purpose was to investigate whether arct

  18. Learning under Concept Drift: an Overview

    CERN Document Server

    e, Indr\\ e Žliobait\\

    2010-01-01

    Concept drift refers to a non stationary learning problem over time. The training and the application data often mismatch in real life problems. In this report we present a context of concept drift problem 1. We focus on the issues relevant to adaptive training set formation. We present the framework and terminology, and formulate a global picture of concept drift learners design. We start with formalizing the framework for the concept drifting data in Section 1. In Section 2 we discuss the adaptivity mechanisms of the concept drift learners. In Section 3 we overview the principle mechanisms of concept drift learners. In this chapter we give a general picture of the available algorithms and categorize them based on their properties. Section 5 discusses the related research fields and Section 5 groups and presents major concept drift applications. This report is intended to give a bird's view of concept drift research field, provide a context of the research and position it within broad spectrum of research fi...

  19. Modeling the cod larvae drift in the Bornholm Basin in summer 1994

    DEFF Research Database (Denmark)

    Hinrichsen, H.H.; Lehmann, A.; St. John, Michael

    1997-01-01

    -dimensional eddy-resolving baroclinic model of the Baltic Sea based on the Bryan-Cox-Semtner code. Larval drift was simulated by the incorporation of a passive tracer into the model utilized to represent individual cod larvae. Additionally, simulated Lagrangian drift trajectories are presented. For model purposes...... with the baroclinic model forced by wind data for the whole Baltic taken from the Europa-Modell (EM) of the German weather service, Offenbach. Verification of simulations was performed by comparison with field measurements of hydrographic variables and ADCP derived current measurements taken during the surveys...

  20. Dissipative drift instability in dusty plasma

    Directory of Open Access Journals (Sweden)

    Nilakshi Das

    2012-03-01

    Full Text Available An investigation has been done on the very low-frequency electrostatic drift waves in a collisional dusty plasma. The dust density gradient is taken perpendicular to the magnetic field B0⃗, which causes the drift wave. In this case, low-frequency drift instabilities can be driven by E1⃗×B0⃗ and diamagnetic drifts, where E1⃗ is the perturbed electric field. Dust charge fluctuation is also taken into consideration for our study. The dust- neutral and ion-neutral collision terms have been included in equations of motion. It is seen that the low-frequency drift instability gets damped in such a system. Both dust charging and collision of plasma particles with the neutrals may be responsible for the damping of the wave. Both analytical and numerical techniques have been used while developing the theory.

  1. Ground Control for Emplacement Drifts for LA

    Energy Technology Data Exchange (ETDEWEB)

    Y. Sun

    2004-07-09

    The purpose of this calculation is to analyze the stability of repository emplacement drifts during the preclosure period, and to provide a final ground support method for emplacement drifts for the License Application (LA). The scope of the work includes determination of input parameter values and loads, selection of appropriate process and methods for the calculation, application of selected methods, such as empirical or analytical, to the calculation, development and execution of numerical models, and evaluation of results. Results from this calculation are limited to use for design of the emplacement drifts and the final ground support system installed in these drifts. The design of non-emplacement openings and their ground support systems is covered in the ''Ground Control for Non-Emplacement Drifts for LA'' (BSC 2004c).

  2. Field investigation of the drift shadow

    Energy Technology Data Exchange (ETDEWEB)

    Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

    2005-09-08

    A drift shadow is an area immediately beneath an undergroundvoidthat, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturatedrock predict the existence of a drift shadow, but field tests confirmingits existence have yet to be performed. Proving the existence of driftshadows and understanding their hydrologic and transport characteristicscould provide a better understanding of how contaminants move in thesubsurface if released from waste emplacement drifts such as the proposednuclear waste repository at Yucca Mountain, Nevada. We describe the fieldprogram that will be used to investigate the existence of a drift shadowand the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch,California. The location and configuration of this mine makes it anexcellent site to observe and measure drift shadow characteristics. Themine is located in a porous sandstone unit of the Domengine Formation, anapproximately 230 meter thick series of interbedded Eocene-age shales,coals, and massive-bedded sandstones. The mining method used at the minerequired the development of two parallel drifts, one above the other,driven along the strike of the mined sandstone stratum. Thisconfiguration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around theunderlying drift. The passive and active hydrologic tests to be performedare described. In the passive method, cores will be obtained in a radialpattern around a drift and will be sectioned and analyzed for in-situwater content and chemical constituents. With the active hydrologic test,water will be introduced into the upper drift of the two parallel driftsand the flow of the water will be tracked as it passes near the bottomdrift. Tensiometers, electrical resistance probes, neutron probes, andground penetrating radar may be

  3. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2011-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers. The differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest drift velocity monitoring results are discussed.

  4. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2010-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers because the drift velocity depends on it. Furthermore the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest pressure monitoring results are discussed.

  5. Photosynthesis–irradiance responses in the Ross Sea, Antarctica: a meta-analysis

    Directory of Open Access Journals (Sweden)

    W. O. Smith Jr.

    2014-12-01

    PsB and α values. No significant difference was detected between stations dominated by diatoms and those dominated by the haptophyte Phaeocystis antarctica. The meta-analysis generally confirms the photosynthetic rates predicted from global analyses that are based solely on temperature and irradiance availability, but suggests that for more accurate predictions of the productivity of polar systems a more detailed model that includes temporal effects of photosynthetic parameters will be required.

  6. Transport and deposition of heavy metals in the Ross Sea Region, Antarctica

    Science.gov (United States)

    Tuohy, Andrea; Bertler, Nancy; Neff, Peter; Edwards, Ross; Emanuelsson, Daniel; Beers, Thomas; Mayewski, Paul

    2015-10-01

    Emissions and long-range transport of toxic metals and metalloids pose a global threat to ecosystems and human health. Global industrialization occurring from the late nineteenth century releases large quantities of pollutants into the Earth's atmosphere. Despite international efforts to mitigate emissions, accumulation of metals is still observed in the most remote regions of the planet. New baseline studies are needed to determine (i) natural background concentration of pollutants, (ii) contributions of anthropogenic emissions, and (iii) potential remobilization of previously deposited metals. Constructing such records requires distinguishing source strength from transport efficiency to the recording site and accounting for local depositional effects. Here we investigate the sensitivity and representation of Southern Hemisphere atmospheric concentrations of heavy metals (Fe, Al, Mn, Pb, Tl, and As) in the Roosevelt Island Climate Evolution (RICE) ice core, a new coastal Antarctic ice core site. Concentration variability with precipitation is explored in daily surface snow samples collected over 70 days, while seasonal deposition is investigated through snow pit sampling. We find that snow sample concentrations increase with particular snow precipitation types (rime and fog) and enhanced meridional atmospheric transport to the site. Snow pit heavy metals peak in summer and also show variable intraannual peaks. Seasonal airmass modeling based on ERA Interim reanalysis data indicates a synoptic shift during the spring and summer months. We conclude that modern heavy metal concentrations are influenced by transport efficiency and scavenging behavior; and thus, time series records from RICE have the potential to provide representative data of regional changes in heavy metals.

  7. Modelling approach to the assessment of biogenic fluxes at a selected Ross Sea site, Antarctica

    Directory of Open Access Journals (Sweden)

    M. Vichi

    2009-07-01

    Full Text Available Several biogeochemical data have been collected in the last 10 years of Italian activity in Antarctica (ABIOCLEAR, ROSSMIZE, BIOSESO-I/II. A comprehensive 1-D biogeochemical model was implemented as a tool to link observations with processes and to investigate the mechanisms that regulate the flux of biogenic material through the water column. The model is ideally located at station B (175° E–74° S and was set up to reproduce the seasonal cycle of phytoplankton and organic matter fluxes as forced by the dominant water column physics over the period 1990–2001. Austral spring-summer bloom conditions are assessed by comparing simulated nutrient drawdown, primary production rates, bacterial respiration and biomass with the available observations. The simulated biogenic fluxes of carbon, nitrogen and silica have been compared with the fluxes derived from sediment traps data. The model reproduces the observed magnitude of the biogenic fluxes, especially those found in the bottom sediment trap, but the peaks are markedly delayed in time. Sensitivity experiments have shown that the characterization of detritus, the choice of the sinking velocity and the degradation rates are crucial for the timing and magnitude of the vertical fluxes. An increase of velocity leads to a shift towards observation but also to an overestimation of the deposition flux which can be counteracted by higher bacterial remineralization rates. Model results suggest that the timing of the observed fluxes depends first and foremost on the timing of surface production and on a combination of size-distribution and quality of the autochtonous biogenic material. It is hypothesized that the bottom sediment trap collects material originated from the rapid sinking of freshly-produced particles and also from the previous year's production period.

  8. Transcatheter Pulmonary Valve Replacement for Right Ventricular Outflow Tract Conduit Dysfunction After the Ross Procedure

    DEFF Research Database (Denmark)

    Gillespie, Matthew J; McElhinney, Doff B; Kreutzer, Jacqueline

    2015-01-01

    BACKGROUND: Right ventricular outflow tract (RVOT) conduit dysfunction is a limitation of the Ross procedure. Transcatheter pulmonary valve replacement (TPVR) could alter the impact of conduit dysfunction and the risk-benefit balance for the Ross procedure. METHODS: Retrospective review of databa...... early outcomes and durable valve function in the majority of Ross patients. Recurrent RVOT obstruction associated with stent fracture was the main reason for reintervention. Coronary compression is not uncommon in Ross patients and should be assessed prior to TPVR....... of databases from 3 prospective Melody TPV (Medtronic Inc, Minneapolis, MN) trials. RESULTS: Among 358 patients who were catheterized with the intent to implant a Melody TPV for RVOT conduit stenosis or regurgitation (PR) as part of 3 prospective multicenter studies, 67 (19%) had a prior Ross procedure....... Of these, 56 (84%) received a Melody valve; in 5 of the 11 patients who did not, the implant was aborted due to concern for coronary artery compression, and 1 implanted patient required emergent surgery for left coronary compression. The RVOT gradient decreased from a median 38 mm Hg to 13.5 mm Hg (p

  9. Solving the drift control problem

    Directory of Open Access Journals (Sweden)

    Melda Ormeci Matoglu

    2015-12-01

    Full Text Available We model the problem of managing capacity in a build-to-order environment as a Brownian drift control problem. We formulate a structured linear program that models a practical discretization of the problem and exploit a strong relationship between relative value functions and dual solutions to develop a functional lower bound for the continuous problem from a dual solution to the discrete problem. Refining the discretization proves a functional strong duality for the continuous problem. The linear programming formulation is so badly scaled, however, that solving it is beyond the capabilities of standard solvers. By demonstrating the equivalence between strongly feasible bases and deterministic unichain policies, we combinatorialize the pivoting process and by exploiting the relationship between dual solutions and relative value functions, develop a mechanism for solving the LP without ever computing its coefficients. Finally, we exploit the relationship between relative value functions and dual solutions to develop a scheme analogous to column generation for refining the discretization so as to drive the gap between the discrete approximation and the continuous problem to zero quickly while keeping the LP small. Computational studies show our scheme is much faster than simply solving a regular discretization of the problem both in terms of finding a policy with a low average cost and in terms of providing a lower bound on the optimal average cost.

  10. Genetic drift of HIV populations in culture.

    Directory of Open Access Journals (Sweden)

    Yegor Voronin

    2009-03-01

    Full Text Available Populations of Human Immunodeficiency Virus type 1 (HIV-1 undergo a surprisingly large amount of genetic drift in infected patients despite very large population sizes, which are predicted to be mostly deterministic. Several models have been proposed to explain this phenomenon, but all of them implicitly assume that the process of virus replication itself does not contribute to genetic drift. We developed an assay to measure the amount of genetic drift for HIV populations replicating in cell culture. The assay relies on creation of HIV populations of known size and measurements of variation in frequency of a neutral allele. Using this assay, we show that HIV undergoes approximately ten times more genetic drift than would be expected from its population size, which we defined as the number of infected cells in the culture. We showed that a large portion of the increase in genetic drift is due to non-synchronous infection of target cells. When infections are synchronized, genetic drift for the virus is only 3-fold higher than expected from its population size. Thus, the stochastic nature of biological processes involved in viral replication contributes to increased genetic drift in HIV populations. We propose that appreciation of these effects will allow better understanding of the evolutionary forces acting on HIV in infected patients.

  11. [Comparative analysis of sea-ice diatom species composition in the seas of Russian Arctic].

    Science.gov (United States)

    Il'iash, L V; Zhitina, L S

    2009-01-01

    Comparative analysis of species composition of ice diatom algae (IDA) of the White, Barents, Kara, Laptev, East Siberian, Chukchi Seas and the Basin of the Arctic Ocean was conducted on the basis of both original and published data. Species composition of IDA counts 567 taxa including 122 centric and 446 pennate diatoms. The freshwater algae composed about 18% of the total species number. In the White Sea, IDA were the most numerous (272 taxa), in the Kara Sea they are the least numerous (57 taxa). The species compositions in different seas differ significantly from each other. Similarity of IDA was consistent with the Arctic Ocean circulation and ice drift. IDA of Chukchi, East Siberian and Laptev Seas are the most similar, as are IDA of White and Kara Seas. Similarity of IDA of Chukchi Sea to those of other seas decrease in the west direction. IDA species differences between regions within one sea could be greater than those between different seas.

  12. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    A technique, the so-called Drift Strip Method (DSM), for improving the CdZnTe detector energy response to hard X-rays and gamma-rays was applied as a pixel geometry. First tests have confirmed that this detector type provides excellent energy resolution and imaging performance. We specifically...... report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  13. Collisional Drift Waves in Stellarator Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2003-10-07

    A computational study of resistive drift waves in the edge plasma of a stellarator with an helical magnetic axis is presented. Three coupled field equations, describing the collisional drift wave dynamics in the linear approximation, are solved as an initial-value problem along the magnetic field line. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.

  14. Current-driven electron drift solitons

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Ali, E-mail: aliahmad79@hotmail.com [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT) Islamabad (Pakistan); Saleem, H. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT) Islamabad (Pakistan)

    2013-12-09

    The soliton formation by the current-driven drift-like wave is investigated for heavier ion (such as barium) plasma experiments planned to be performed in future. It is pointed out that the sheared flow of electrons can give rise to short scale solitary structures in the presence of stationary heavier ions. The nonlinearity appears due to convective term in the parallel equation of motion and not because of temperature gradient unlike the case of low frequency usual drift wave soliton. This higher frequency drift-like wave requires sheared flow of electrons and not the density gradient to exist.

  15. Nonlinear Gyrokinetic Theory With Polarization Drift

    Energy Technology Data Exchange (ETDEWEB)

    L. Wang and T.S. Hahm

    2010-03-25

    A set of the electrostatic toroidal gyrokinetic Vlasov equation and the Poisson equation, which explicitly includes the polarization drift, is derived systematically by using Lie-transform method. The polarization drift is introduced in the gyrocenter equations of motion, and the corresponding polarization density is derived. Contrary to the wide-spread expectation, the inclusion of the polarization drift in the gyrocenter equations of motion does not affect the expression for the polarization density significantly. This is due to modification of the gyrocenter phase-space volume caused by the electrostatic potential [T. S. Hahm, Phys. Plasmas 3, 4658 (1996)] .

  16. Sea ice dynamics and the role of wind forcing over the Beaufort Sea

    Science.gov (United States)

    Petty, A.; Hutchings, J. K.; Farrell, S. L.; Richter-Menge, J.; Tschudi, M. A.

    2014-12-01

    Both the ocean circulation and overlying sea ice cover of the Beaufort and Chukchi seas have experienced significant change in recent decades. We use sea ice drift estimates from satellite feature tracking (NSIDC/CERSAT), wind forcing from atmospheric reanalysis products (NCEP-R2/ERA-I/JRA-55), and ice type information from satellite and direct ship-based observations (obtained during the Beaufort Gyre Exploration Project), to investigate the role of wind forcing and ice mechanics in driving these changes. An assessment of ice drift shows reasonable agreement across the different products, revealing interannual variability in the ice flux around the Beaufort Sea. However, clear uncertainties remain in determining the magnitude of these fluxes, especially in regions of low ice concentration. We find an increase in ice export out of the southern Beaufort Sea (into the Chukchi Sea) across all seasons. We find slight differences in the strength of the decadal (1980-2013) trends in the mean seasonal wind curl over the Beaufort Sea, although all reanalysis products indicate a strong and significant increase in anti-cyclonic winds in summer. Analysis of ice drift curl suggests increasing anti-cyclonic drift across all seasons, despite the wind curl showing a similar trend in summer only. The strongest trend in ice drift curl appears to be in autumn, however recent years have seen a strong reduction in this anti-cyclonic drift, likely due to a combination of changes in the wind forcing and sea ice state. The implication of this finding is an enhanced response of the ocean circulation to shifts in atmospheric circulation compared to that experienced prior to 2000.

  17. Recent wind driven high sea ice export in the Fram Strait contributes to Arctic sea ice decline

    Directory of Open Access Journals (Sweden)

    L. H. Smedsrud

    2011-05-01

    Full Text Available Arctic sea ice area decrease has been visible for two decades, and continues at a steady rate. Apart from melting, the southward drift through Fram Strait is the main loss. We present high resolution sea ice drift across 79° N from 2004 to 2010. The ice drift is based on radar satellite data and correspond well with variability in local geostrophic wind. The underlying current contributes with a constant southward speed close to 5 cm s−1, and drives about 33 % of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25 % larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice export likely has a significant influence on the summer sea ice variability and we find low values in the 60's, the late 80's and 90's, and particularly high values during 2005–2008. The study highlight the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice the last decades.

  18. Ice-Core Study of the Link between Sea-Salt Aerosol, Sea-Ice Cover and Climate in the Antarctic Peninsula Area

    Energy Technology Data Exchange (ETDEWEB)

    Aristarain, A.J. [Laboratorio de Estratigrafia Glaciar y Geoquimica del Agua y de la Nieve LEGAN, Instituto Antartico Argentino, Mendoza (Argentina); Delmas, R.J. [Laboratoire de Glaciologie et Geophysique de l' Environnement LGGE, Centre National de la Recherche Scientifique, BP 96, 38402 St. Martin d' Heres Cedex (France); Stievenard, M. [Laboratoire des Sciences du Climat et de l' Environnement LSCE, Centre d' Etudes de Saclay, 91191 Gif-sur-Yvette, Cedex (France)

    2004-11-01

    Three ice cores and a set of snow pit samples collected on James Ross Island, Antarctic Peninsula, in 1979, 1981 and 1991 have been analyzed for water stable isotope content D or 18O (isotopic temperature) and major chemical species. A reliable and detailed chronological scale has been established first for the upper 24.5 m of water equivalent (1990-1943) where various data sets can be compared, then extended down to 59.5 m of water equivalent (1847) with the aid of seasonal variations and the sulphate peak reflecting the 1883 Krakatoa volcanic eruption. At James Ross Island, sea-salt aerosol is generally produced by ice-free marine surfaces during the summer months, although some winter sea-salt events have been observed. For the upper part of the core (1990-1943), correlations (positive or negative) were calculated between isotopic temperature, chloride content (a sea-salt indicator), sea-ice extent, regional atmospheric temperature changes and atmospheric circulation. The D and chloride content correlation was then extended back to 1847, making it possible to estimate decadal sea-ice cover fluctuations over the study period. Our findings suggest that ice-core records from James Ross Island reflect the recent warming and sea-ice decrease trends observed in the Antarctic Peninsula area from the mid-1940s.

  19. Identifying the role of reactive oxygen species (ROSs) in Fusarium solani spores inactivation.

    Science.gov (United States)

    Du, Yilin; Xiong, Houfeng; Dong, Shuangshi; Zhang, Jun; Ma, Dongmei; Zhou, Dandan

    2016-12-01

    The inactivation mechanism of photocatalytic disinfectants on bacteria is well known. In contrast, the potential inactivation of fungal spores by visible-light induced photocatalysis has been recognized, but the inactivation mechanism is poorly understood. We hypothesize that photocatalytically generated reactive oxygen species (ROSs) are directly involved in this mechanism. To test this hypothesis, we identified the roles of ROSs in the inactivation of Fusarium solani spores. As the photocatalysts, we doped TiO2 with 3 typical dopants, forming Ag/TiO2, N/TiO2 and Er(3+):YAlO3/TiO2. The Ag/TiO2 photocatalysis was dominated by H2O2, with the longest lifetime among the investigated ROSs. Ag/TiO2 photocatalysis yielded almost 100 % inactivation efficiency and preserved the cell-wall shape of the spores, thus minimizing the biomolecule leakage. Er(3+):YAlO3/TiO2 was dominated by h(+) ROSs, yielding an inactivation efficiency of 91 %; however, the severe leakage released large numbers of molecular bio-products. Severe damage to the cell walls by the h(+) species was confirmed in micrograph observations. Subsequent to cell wall breakage, the Er(3+):YAlO3/TiO2 nanoparticles entered the spore cells and directly oxidized the intracellular material. The N/TiO2 photocatalysis, with •O2(-) dominated ROSs, delivered intermediate performance. In conclusion, photocatalysts that generate H2O2-dominated ROSs are most preferred for spore inactivation.

  20. Vacuum condensates and `ether-drift' experiments

    OpenAIRE

    Consoli, M.; Pagano, A.; Pappalardo, L.

    2003-01-01

    The idea of a `condensed' vacuum state is generally accepted in modern elementary particle physics. We argue that this should motivate a new generation of precise `ether-drift' experiments with present-day technology.

  1. An analytical model of iceberg drift

    CERN Document Server

    Wagner, Till J W; Eisenman, Ian

    2016-01-01

    Iceberg drift and decay and the associated freshwater release are increasingly seen as important processes in Earth's climate system, yet a detailed understanding of their dynamics has remained elusive. Here, an idealized model of iceberg drift is presented. The model is designed to include the most salient physical processes that determine iceberg motion while remaining sufficiently simple to facilitate physical insight into iceberg drift dynamics. We derive an analytical solution of the model, which helps build understanding and also enables the rapid computation of large numbers of iceberg trajectories. The long-standing empirical rule of thumb that icebergs drift at 2% of the wind velocity, relative to the ocean current, is derived here from physical first principles, and it is shown that this relation only holds in the limit of strong winds or small icebergs, which approximately applies for typical icebergs in the Arctic. It is demonstrated that the opposite limit of weak winds or large icebergs approxim...

  2. Stabilization Strategies for Drift Tube Linacs

    CERN Document Server

    AUTHOR|(CDS)2085420; Lamehi Rashti, Mohammad

    The average axial electric fields in drift tube linac cavities are known to be sensitive with respect to the perturbation errors. Postcoupler is a powerful stabilizer devices that is used to reduce this sensitivity of average axial field. Postcouplers are the cylindrical rod which is extended from cavity wall toward the drift tube without touching the drift tube surface. Postcouplers need to be adjusted to the right length to stabilize the average axial field. Although postcouplers are used successfully in many projects, there is no straightforward procedure for postcouplers adjustment and it has been done almost based on trial and errors. In this thesis, the physics and characteristics of postcouplers has been studied by using an equivalent circuit model and 3D finite element method calculations. Finally, a straightforward and accurate method to adjust postcouplers has been concluded. The method has been verified by using experimental measurements on CERN Linac4 drift tube linac cavities.

  3. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    S. Goodin

    1999-07-08

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches.

  4. The Electron Drift Instrument for MMS

    Science.gov (United States)

    Torbert, R. B.; Vaith, H.; Granoff, M.; Widholm, M.; Gaidos, J. A.; Briggs, B. H.; Dors, I. G.; Chutter, M. W.; Macri, J.; Argall, M.; Bodet, D.; Needell, J.; Steller, M. B.; Baumjohann, W.; Nakamura, R.; Plaschke, F.; Ottacher, H.; Hasiba, J.; Hofmann, K.; Kletzing, C. A.; Bounds, S. R.; Dvorsky, R. T.; Sigsbee, K.; Kooi, V.

    2016-03-01

    The Electron Drift Instrument (EDI) on the Magnetospheric Multiscale (MMS) mission measures the in-situ electric and magnetic fields using the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one or more gyrations. This drift is related to the electric field and, to a lesser extent, the gradient in the magnetic field. Although these two quantities can be determined separately by use of different electron energies, for MMS regions of interest the magnetic field gradient contribution is negligible. As a by-product of the drift determination, the magnetic field strength and constraints on its direction are also determined. The present paper describes the scientific objectives, the experimental method, and the technical realization of the various elements of the instrument on MMS.

  5. Nonlinear electrostatic drift Kelvin-Helmholtz instability

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1993-01-01

    Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves, and the nonlinear behavior is governed by the nonlinear Burger's equation.

  6. Self-shielding flex-circuit drift tube, drift tube assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Jones, David Alexander

    2016-04-26

    The present disclosure is directed to an ion mobility drift tube fabricated using flex-circuit technology in which every other drift electrode is on a different layer of the flex-circuit and each drift electrode partially overlaps the adjacent electrodes on the other layer. This results in a self-shielding effect where the drift electrodes themselves shield the interior of the drift tube from unwanted electro-magnetic noise. In addition, this drift tube can be manufactured with an integral flex-heater for temperature control. This design will significantly improve the noise immunity, size, weight, and power requirements of hand-held ion mobility systems such as those used for explosive detection.

  7. 78 FR 12357 - Brockway Mould, Inc., a Division of Ross International Ltd. Including Robert Lerch From BJR...

    Science.gov (United States)

    2013-02-22

    ... Employment and Training Administration Brockway Mould, Inc., a Division of Ross International Ltd. Including... Brockway Mould, Inc., a division of Ross International Ltd, Brockport, Pennsylvania (subject firm). The...,862 is hereby issued as follows: ``All workers from Brockway Mould, Inc., a division of...

  8. The Bipolar Quantum Drift-diffusion Model

    Institute of Scientific and Technical Information of China (English)

    Xiu Qing CHEN; Li CHEN

    2009-01-01

    A fourth order parabolic system, the bipolar quantum drift-diffusion model in semiconductor simulation, with physically motivated Dirichlet-Neumann boundary condition is studied in this paper. By semidiscretization in time and compactness argument, the global existence and semiclassical limit are obtained, in which semiclassical limit describes the relation between quantum and classical drift-diffusion models. Furthermore, in the case of constant doping, we prove the weak solution exponentially approaches its constant steady state as time increases to infinity.

  9. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  10. Strange Attractors in Drift Wave Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2003-04-25

    A multi-grid part-in-cell algorithm for a shearless slab drift wave model with kinetic electrons is presented. The algorithm, which is based on an exact separation of adiabatic and nonadiabatic electron responses, is used to investigate the presence of strange attractors in drift wave turbulence. Although the simulation model has a large number of degrees of freedom, it is found that the strange attractor is low-dimensional and that it is strongly affected by dissipative (collisional) effects.

  11. Thermodynamics Insights for the Redshift Drift

    Science.gov (United States)

    Zhang, Ming-Jian; Liu, Wen-Biao

    2015-01-01

    The secular redshift drift is a potential measurement to directly probe the cosmic expansion. Previous study on the redshift drift mainly focused on the model-dependent simulation. Apparently, the physical insights on the redshift drift are very necessary. So in this paper, it is investigated using thermodynamics on the apparent, Hubble and event horizons. Thermodynamics could analytically present the model-independent upper bounds of redshift drift. For specific assumption on the cosmological parameters, we find that the thermodynamics bounds are nearly one order of magnitude larger than the expectation in standard ΛCDM model. We then examine ten observed redshift drift from Green Bank Telescope at redshift 0.09 < z < 0.69, and find that these observational results are inconsistent with the thermodynamics. The size of the errorbars on these measurements is about three orders of magnitude larger than the effect of thermodynamical bounds for the redshift drift. Obviously, we have not yet hit any instrumental systematics at the shift level of 1m s-1 yr-1.

  12. Suppressing drift chamber diffusion without magnetic field

    CERN Document Server

    Martoff, C J; Ohnuki, T; Spooner, N J C; Lehner, M

    2000-01-01

    The spatial resolution in drift chamber detectors for ionizing radiation is limited by diffusion of the primary electrons. A strong magnetic field along the drift direction is often applied (Fancher et al., Nucl. Instr. and Meth. A 161 (1979) 383) because it suppresses the transverse diffusion, improving the resolution but at considerable increase in cost and complexity. Here we show that transverse track diffusion can be strongly suppressed without any magnetic field. This is achieved by using a gas additive which reversibly captures primary ionization electrons, forming negative ions. The ions drift with thermal energies even at very high drift fields and low pressures (E/P=28.5 V/cm torr), and the diffusion decreases with increasing drift field. Upon arrival at the avalanche region of the chamber the negative ions are efficiently stripped and ordinary avalanche gain is obtained. Using this technique, r.m.s. transverse diffusion less than 200 mu m has been achieved over a 15 cm drift path at 40 torr with ze...

  13. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

    INSPIRE-00165402; Khachatryan, V; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; 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    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  14. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

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Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  15. Remote sensing of seawater and drifting ice in Svalbard fjords by compact Raman LIDAR

    CERN Document Server

    Bunkin, Alexey F; Lednev, Vasily N; Lushnikov, Dmitry L; Marchenko, Aleksey V; Morozov, Eugene G; Pershin, Sergey M; Yulmetov, Renat N

    2013-01-01

    A compact Raman LIDAR system for remote sensing of sea and drifting ice was developed at the Wave Research Center at the Prokhorov General Physics Institute of the RAS. The developed system is based on a diode pumped solid state YVO4:Nd laser combined with compact spectrograph equipped with gated detector. The system exhibits high sensitivity and can be used for mapping or depth profiling of different parameters within many oceanographic problems. Light weight (~20 kg) and low power consumption (300 W) make possible to install the device on any vehicle including unmanned aircraft or submarine system. The Raman LIDAR presented was used for Svalbard fjords study and analysis of different influence of the open sea and glaciers on the water properties. Temperature, phytoplankton, and dissolved organic matter distributions in the seawater were studied in the Ice Fjord, Van Mijen Fjord and Rinders Fjord. Drifting ice and seawater in the Rinders Fjord were characterized by the Raman spectroscopy and fluorescence. It...

  16. Lesser snow geese and ross's geese form mixed flocks during winter but differ in family maintenance and social status

    Science.gov (United States)

    Jonsson, J.E.; Afton, A.D.

    2008-01-01

    Smaller species are less likely to maintain families (or other forms of social groups) than larger species and are more likely to be displaced in competition with larger species. We observed mixed-species flocks of geese in southwest Louisiana and compared frequencies of social groups and success in social encounters of Lesser Snow Geese (Chen caerulescens caerulescens; hereafter Snow Geese) with that of the smaller, closely- related Ross's Geese (C. rossii). Less than 7% of adult and social encounters and had higher odds of success against Ross's Geese than against individuals of their own species. The larger Snow Geese maintain families longer than Ross's Geese, which probably contributes to their dominance over Ross's Geese during winter. Predator vigilance probably is an important benefit of mixed flocking for both species. We suggest the long-standing association with Snow Geese (along with associated subordinate social status) has selected against family maintenance in Ross's Geese.

  17. Baleen whale spatial patterns in the Scotia Sea during January and February 2003

    OpenAIRE

    2006-01-01

    Different species of baleen whales display distinct spatial distribution patterns in the Scotia Sea during the austral summer. Passive acoustic and visual surveys for baleen whales were conducted aboard the RRS James Clark Ross in the Scotia Sea and around South Georgia in January and February 2003. Identified calls from four species were recorded during the acoustic survey including southern right (Eubalaena australis), blue (Balaenoptera musculus), fin (B. physalus) and humpback whales (Meg...

  18. Modeling the impact of Australian Plate drift on Southern Hemisphere climate and environment

    Institute of Scientific and Technical Information of China (English)

    ZHOU Botao; ZHAO Ping; JIAN Zhimin; HE Jinhai

    2005-01-01

    Using a global atmosphere-ocean coupled model with the present-day and 14 MaB.P. oceanic topography respectively, two experiments are implemented to investigate the effect of different locations of Australian Plate on the atmospheric circulation in middle-high latitudes of the Southern Hemisphere. The results show that when Australian Plate lay south at 14 MaB.P., both anticyclone circulations in the subtropical oceans and cyclone circulation around 60°-70°S are strengthened. Subtropical highs and circumpolar low pressure appear stronger, which results in much stronger Antarctic Oscillation and shorter period of Antarctic Oscillation Index (AOI) at 14 MaB.P. The rainfall and the surface air temperature also change correspondingly. The precipitation decreases around 40°S and increases around 60°-70°S, and the surface air temperature rises in high latitudes of the South Pacific and descends over the Weddell Sea and its north side. Besides, due to the changes of the temperatures and winds, Antarctic sea ice coverage also changes with its increasing in the Ross Sea and its west regions and decreasing in the Weddell Sea.

  19. Relationship between Antarctic sea ice and the climate in summer of China

    Institute of Scientific and Technical Information of China (English)

    Ma Lijuan; Lu Longhua; Bian Lingen

    2006-01-01

    The variations of sea ice are different in different regions in Antarctica,thus have different impacts on local atmospheric circulation and global climatic system. The relationships between the sea ice in Ross Sea and Weddell Sea regions and the synoptic climate in summer of China are investigated in this paper via diagnostic analysis methods by using global sea ice concentration gridded data covering Jan. 1968through Dec. 2002 obtained from Hadley Center, combined with Geopotential Height on 500hPa and 100hPa over North Hemisphere and monthly precipitation and air temperatures data covering the corresponding period over 160 meteorological stations in China obtained from CMA (China Meteorological Administration). Results disclose that both these two regions are of indicative meanings to the climate in summer of China. The Ross Sea Region is the key sea ice region to the precipitation in Northeast China in summer. More sea ice in this region in September will result in less precipitation in Northeast China in the following June. Weddell Sea Region is the key sea ice region to the air temperature in Northeast China in summer. More sea ice in this region in September will contribute to lower air temperature in Northeast China in the following June.

  20. On the design and construction of drifting-mine test targets for sonar, radar and electro-optical detection experiments

    NARCIS (Netherlands)

    Dol, H.S.

    2014-01-01

    The timely detection of small hazardous objects at the sea surface, such as drifting mines, is challenging for ship-mounted sensor systems, both for underwater sensor systems like sonar and above-water sensor systems like radar and electro-optics (lidar, infrared/visual cameras). This is due to the

  1. Concentrated Hitting Times of Randomized Search Heuristics with Variable Drift

    DEFF Research Database (Denmark)

    Lehre, Per Kristian; Witt, Carsten

    2014-01-01

    these results handle a position-dependent (variable) drift that was not covered by previous drift theorems with tail bounds. Moreover, our theorem can be specialized into virtually all existing drift theorems with drift towards the target from the literature. Finally, user-friendly specializations...

  2. Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004

    Science.gov (United States)

    Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S.

    2007-01-01

    Changes in the area and volume of polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level could severely impact the densely populated coastal regions on Earth. Melting of the West Antarctic part alone of the Antarctic ice sheet would cause a sea-level rise of approximately 6 meters (m). The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). The mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is highly complex, responding differently to different conditions in each region (Vaughan, 2005). In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic ice sheet is probably becoming thinner overall; although it is thickening in the west, it is thinning in the north. Thomas and others (2004), on the basis of aircraft and satellite laser altimetry surveys, believe the thinning may be accelerating. Joughin and Tulaczyk (2002), on the basis of analysis of ice-flow velocities derived from synthetic aperture radar, concluded that most of the Ross ice streams (ice streams on the east side of the Ross Ice Shelf) have a positive mass balance, whereas Rignot and others (2004) infer even larger negative mass balance for glaciers flowing northward into the Amundsen Sea, a trend suggested by Swithinbank and others (2003a,b; 2004). The mass balance of the East Antarctic ice sheet is thought by Davis and others (2005) to be strongly positive on the basis of the change in satellite altimetry measurements made between 1992 and 2003. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation?s (1990) Division of Polar

  3. Sea Surface Temperature Climate Data Record for the North Sea and Baltic Sea

    DEFF Research Database (Denmark)

    Høyer, Jacob L.; Karagali, Ioanna

    2016-01-01

    A 30-yr climate data record (CDR) of sea surface temperature (SST) has been produced with daily gap-free analysis fields for the North Sea and the Baltic Sea region from 1982 to 2012 by combining the Pathfinder AVHRR satellite data record with the Along-Track Scanning Radiometer (ATSR) Reprocessing...... observations on average. Validation against independent in situ observations shows a very stable performance of the data record, with a mean difference of -0.06 °C compared to moored buoys and a 0.46 °C standard deviation of the differences. The mean annual biases of the SST CDR are small for all years......, with a negligible temporal trend when compared against drifting and moored buoys. Analysis of the SST CDR reveals that the monthly anomalies for the North Sea, the Danish straits, and the central Baltic Sea regions show a high degree of correlation for interannual and decadal time scales, whereas the monthly...

  4. Floquet-Bloch vs. Nicolson-Ross-Weir Extraction for Magneto-Dielectric Bragg Stacks

    DEFF Research Database (Denmark)

    Clausen, Niels Christian Jerichau; Arslanagic, Samel; Breinbjerg, Olav

    2014-01-01

    We extract and compare the permittivity and permeability from a dielectric and a magnetodielectric Bragg stack with the Floquet-Bloch (FB) method for the infinite stack and the Nicolson-Ross- Weir (NRW) method for the finite stack. While the extracted propagation constants are identical, the wave...

  5. Ross procedure in a child with Aspergillus endocarditis and bicuspid aortic valve.

    Science.gov (United States)

    Mitropoulos, Fotios A; Kanakis, Meletios A; Contrafouris, Constantinos; Laskari, Cleo; Rammos, Spyridon; Apostolidis, Christos; Azariadis, Prodromos; Chatzis, Andrew C

    2014-08-23

    The case is presented of a previously healthy infant with a known asymptomatic bicuspid aortic valve who developed fungal endocarditis. The patient underwent aortic root replacement with a pulmonary autograft (Ross procedure). Cultured operative material revealed Aspergillus infection. The patient had an excellent recovery and remained well one year later.

  6. Ross river virus disease in two Dutch travelers returning from Australia, February to April 2015

    NARCIS (Netherlands)

    C.B.E.M. Reusken (Chantal); N.B. Cleton (Natalie); M.M. Melo (M. Medonça); C. Visser; C.G. Van Kessel (C. Geurts); P. Bloembergen; M.P.G. Koopmans D.V.M. (Marion); J. Schmidt-Chanasit (Jonas); P. van Genderen

    2015-01-01

    textabstractWe report two cases of Ross River virus (RRV) infection in Dutch travellers who visited Australia during February to April 2015. These cases coincided with the largest recorded outbreak of RRV disease in Australia since 1996. This report serves to create awareness among physicians to

  7. Ross River virus disease in two Dutch travellers returning from Australia, February to April 2015

    NARCIS (Netherlands)

    C.B.E.M. Reusken (Chantal); N.B. Cleton (Natalie); M. Medonça Melo; C. Visser; C.H. Geurts van Kessel (Corine); P. Bloembergen; M.P.G. Koopmans D.V.M. (Marion); J. Schmidt-Chanasit (Jonas); P. van Genderen

    2015-01-01

    textabstractWe report two cases of Ross River virus (RRV) infection in Dutch travellers who visited Australia during February to April 2015. These cases coincided with the largest recorded outbreak of RRV disease in Australia since 1996. This report serves to create awareness among physicians to

  8. TEST OF THE CHEN-ROLL-ROSS MACROECONOMIC FACTOR MODEL: EVIDENCE FROM CROATIAN STOCK MARKET

    Directory of Open Access Journals (Sweden)

    Denis Dolinar

    2015-12-01

    Full Text Available This paper empirically examines the well-known Chen-Roll-Ross model on the Croatian stock market. Modifications of definitions of the Chen-Roll-Ross model variables showed as necessary because of doubtful availability and quality of input data needed. Namely, some macroeconomic and market variables are not available in the originally defined form or do not exist. In that sense this paper gives some alternative definitions for some model variables. Also, in order to improve statistical analysis, in this paper we have modified Fama-MacBeth technique in the way that second-pass regression was substituted with panel regression analysis. Based on the two-pass regression analysis of returns of 34 Croatian stocks on 4 macroeconomic variables during the seven-and-half-year observation period the following conclusion is made. In contrast to the results of Chen, Roll and Ross (1986 for the U.S. stock market, their model is not successful when describing a risk-return relation of Croatian stocks. Nevertheless, one observed version of the Chen-RollRoss model showed certain statistical significance. Namely, two risk factors in that version of the model were statistically significant: default premium, measured as risk premium for the corporate short-term bank loan financing, and term structure premium, measured on short-run basis.

  9. STS-37 Mission Specialist (MS) Ross during simulation in JSC's FB-SMS

    Science.gov (United States)

    1991-01-01

    STS-37 Mission Specialist (MS) Jerry L. Ross 'borrows' the pilots station to rehearse some of his scheduled duties for his upcoming mission. He is on the flight deck of the fixed-based (FB) shuttle mission simulator (SMS) during this unsuited simulation. The SMS is part of JSC's Mission Simulation and Training Facility Bldg 5.

  10. Märten Ross sõnastas majanduskriisi õppetunnid / Argo Ideon

    Index Scriptorium Estoniae

    Ideon, Argo, 1966-

    2011-01-01

    Ajutiselt peaministri majandus- ja rahandusnõunikuna töötanud endine Eesti Panga asepresident Märten Ross kirjutas loetelu õppetundidest, mida Eesti majanduspoliitika peaks arvestama 2008.-2009. aasta kriisi põhjal. Rossi 10 punkti lühidalt. Rahandusminister Jürgen Ligi ning Eesti Panga rahapoliitika ja majandusuuringute osakonna asejuhataja Martin Lindpere arvamus

  11. A Helping Hand in the Frederick Community—Ross Smith | Poster

    Science.gov (United States)

    By day, Ross Smith is the compliance and security officer for Data Management Services, Inc., assigned to the National Cancer Institute (NCI) at Frederick. His role is to ensure the secure operation of in-house computer systems, servers, and network connections. But in his spare time, Smith is also a volunteer firefighter and emergency medical technician (EMT).

  12. Astronauts Ross and Helms at CAPCOM station during STS-61 simulations

    Science.gov (United States)

    1993-01-01

    Astronauts Jerry L. Ross and Susan J. Helms are pictured at the Spacecraft Communicators console during joint integrated simulations for the STS-61 mission. Astronauts assigned to extravehicular activity (EVA) tasks with the Hubble Space Telescope (HST) were simultaneously rehearsing in a neutral buoyancy tank at the Marshall Space Flight Center (MSFC) in Alabama.

  13. Photographer: Digital Telepresence: Dr Murial Ross's Virtual Reality Application for Neuroscience

    Science.gov (United States)

    1995-01-01

    Photographer: Digital Telepresence: Dr Murial Ross's Virtual Reality Application for Neuroscience Research Biocomputation. To study human disorders of balance and space motion sickness. Shown here is a 3D reconstruction of a nerve ending in inner ear, nature's wiring of balance organs.

  14. A Q-Methodological Study of the Kubler-Ross Stage Theory.

    Science.gov (United States)

    Metzger, Anne M.

    1979-01-01

    Investigated the correspondence between stage changes hypothesized by the Kubler-Ross theory and the perception of the course of illness by seriously ill patients and their spouses. Supported the use of Q-methodology as a research procedure for investigations of terminal illness. (Author)

  15. Assessing competition with the Panzar-Rosse model : the role of scale, costs, and equilibrium

    NARCIS (Netherlands)

    Bikker, Jacob A.; Shaffer, Sherrill; Spierdijk, Laura

    2012-01-01

    The Panzar-Rosse test has been widely applied to assess competitive conduct, often in specifications controlling for firm scale or using a price equation. We show that neither a price equation nor a scaled revenue function yields a valid measure for competitive conduct. Moreover, even an unscaled re

  16. Electron drift velocities in fast Argon and CF4 based drift gases

    CERN Document Server

    van Apeldoorn, G

    1998-01-01

    98-063 Electron drift velocities in gas mixtures were measured in a tabletop experiment using a nitrogen laser to create the primary electrons. The maximum drift times for electrons in a 5 mm (10 mm) honeycomb drift cell at 2200 V anode voltage were 28 ns (53 ns) and 21 ns (61 ns) for Ar-Cf4-CH4 (75/18/6) and Ar-CF4-CO2 (68/27/5), respectively. Changing the ratio of the latter mix did not change the drift velocity very much. The gains of the gases are ~10^4 for a single primary electron. CF4 causes electron attachment. The measured drift times agree well with GARFIELD simulations.

  17. Jet formation at the sea ice edge

    Science.gov (United States)

    Feltham, D. L.; Heorton, H. D.

    2014-12-01

    The sea ice edge presents a region of many feedback processes between the atmosphere, ocean and sea ice, which are inadequately represented in current climate models. Here we focus on on-ice atmospheric and oceanic flows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere flowing over, and ocean flowing under, a compacted sea ice edge. We have studied a dynamic sea ice edge responding to atmospheric and oceanic jet formation. The shape and strength of atmospheric and oceanic jets during on-ice flows is calculated from existing studies of the sea ice edge and prescribed to idealised models of the sea ice edge. An idealised analytical model of sea ice drift is developed and compared to a sea ice climate model (the CICE model) run on an idealised domain. The response of the CICE model to jet formation is tested at various resolutions. We find that the formation of atmospheric jets during on-ice winds at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The modelled sea ice edge jet is in agreement with an observed jet although more observations are needed for validation. The increase in ice drift speed is dependent upon the angle between the ice edge and wind and can result in a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation during on-ice currents and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

  18. Seabird drift as a proxy to estimate surface currents in the western Mediterranean?

    Science.gov (United States)

    Gomez-Navarro, Laura; Sánchez-Román, Antonio; Pascual, Ananda; Fablet, Ronan; Hernandez-Carrasco, Ismael; Mason, Evan; Arcos, José Manuel; Oro, Daniel

    2017-04-01

    Seabird trajectories can be used as proxies to investigate the dynamics of marine systems and their spatiotemporal evolution. Previous studies have mainly been based on analyses of long range flights, where birds are travelling at high velocities over long time periods. Such data have been used to study wind patterns, and areas of avian feeding and foraging have also been used to study oceanic fronts. Here we focus on "slow moving" periods (which we associate to when birds appear to be drifting on the sea surface), in order to investigate bird drift as a proxy for sea surface currents in the western Mediterranean Sea. We analyse trajectories corresponding to "slow moving" periods recorded by GPSs attached to individuals of the species Calonectris diomedea ( Scopoli's shearwater) from mid August to mid September 2012. The trajectories are compared with sea level anomaly (SLA), sea surface temperature (SST), Finite Size Lyapunov Exponents (FSLE), wind fields, and the outputs from an automated sea-surface-height based eddy tracker. The SLA and SST datasets were obtained from the Copernicus Marine Environment Monitoring Service (CMEMS) with a spatial resolution of 1/8 ̊ and 1/100 ̊ respectively while the FSLEs were computed from the SLA dataset. Finally, the wind data comes from the outputs of the CCMPv2 numerical model. This model has a global coverage with a spatial resolution of 1/4 ̊. Interesting relationships between the trajectories and SLA fields are found. According to the angle between the SLA gradient and the trajectories of birds, we classify drifts into three scenarios: perpendicular, parallel and other, which are associated with different driving forces. The first scenario implies that bird drift is driven by geostrophic sea surface currents. The second we associate with wind drag as the main driving force. This is validated through the wind dataset. Moreover, from the SST, FSLEs and the eddy tracker, we obtain supplementary information on the presence

  19. The KLOE drift chamber VCI 2001

    Energy Technology Data Exchange (ETDEWEB)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervell, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; De Lucia, E. E-mail: erika.delucia@roma1.infn.it; De Robertis, G.; De Sangro, R.; De Simone, P.; De Zorzi, G.; Dell' Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U. von.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y

    2002-02-01

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum K{sub L} ({lambda}{sub L}=3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged K{sub L} decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed.

  20. Epigenetic drift, epigenetic clocks and cancer risk.

    Science.gov (United States)

    Zheng, Shijie C; Widschwendter, Martin; Teschendorff, Andrew E

    2016-05-01

    It is well-established that the DNA methylation landscape of normal cells undergoes a gradual modification with age, termed as 'epigenetic drift'. Here, we review the current state of knowledge of epigenetic drift and its potential role in cancer etiology. We propose a new terminology to help distinguish the different components of epigenetic drift, with the aim of clarifying the role of the epigenetic clock, mitotic clocks and active changes, which accumulate in response to environmental disease risk factors. We further highlight the growing evidence that epigenetic changes associated with cancer risk factors may play an important causal role in cancer development, and that monitoring these molecular changes in normal cells may offer novel risk prediction and disease prevention strategies.

  1. The KLOE drift chamber VCI 2001

    CERN Document Server

    Adinolfi, M; Ambrosino, F; Andryakov, A; Antonelli, A; Antonelli, M; Anulli, F; Bacci, C; Bankamp, A; Barbiellini, G; Bellini, F; Bencivenni, G; Bertolucci, Sergio; Bini, C; Bloise, C; Bocci, V; Bossi, F; Branchini, P; Bulychjov, S A; Cabibbo, G; Calcaterra, A; Caloi, R; Campana, P; Capon, G; Carboni, G; Cardini, A; Casarsa, M; Cataldi, G; Ceradini, F; Cervell, F; Cevenini, F; Chiefari, G; Ciambrone, P; Conetti, S; Conticelli, S; De Lucia, E; De Robertis, G; De Simone, P; De Zorzi, G; De Sangro, R; Dell'Agnello, S; Denig, A; Di Domenico, A; Di Donato, C; Di Falco, S; Doria, A; Drago, E; Elia, V; Erriquez, O; Farilla, A; Felici, G; Ferrari, A; Ferrer, M L; Finocchiaro, G; Forti, C; Franceschi, A; Franzini, P; Gao, M L; Gatti, C; Gauzzi, P; Giovannella, S; Golovatyuk, V; Gorini, E; Grancagnolo, F; Grandegger, W; Graziani, E; Guarnaccia, P; Han, H G; Han, S W; Huang, X; Incagli, M; Ingrosso, L; Jang, Y Y; Kim, W; Kluge, W; Kulikov, V; Lacava, F; Lanfranchi, G; Lee-Franzini, J; Lomtadze, F; Luisi, C; Mao Chen Sheng; Martemyanov, M; Matsyuk, M; Mei, W; Merola, L; Messi, R; Miscetti, S; Moalem, A; Moccia, S; Moulson, M; Murtas, F; Müller, S; Napolitano, M; Nedosekin, A; Pacciani, L; Pagès, P; Palutan, M; Panareo, M; Paoluzi, L; Pasqualucci, E; Passalacqua, L; Passaseo, M; Passeri, A; Patera, V; Petrolo, E; Petrucci, Guido; Picca, D; Pirozzi, G; Pistillo, C; Pollack, M; Pontecorvo, L; Primavera, M; Ruggieri, F; Santangelo, P; Santovetti, E; Saracino, G; Schamberger, R D; Schwick, C; Sciascia, B; Sciubba, A; Scuri, F; Sfiligoi, I; Shan, J; Silano, P; Spadaro, T; Spagnolo, S; Spiriti, E; Stanescu, C; Tong, G L; Tortora, L; Valente, E; Valente, P; Valeriani, B; Venanzoni, G; Veneziano, Stefano; Von Hagel, U; Wu, Y; Xie, Y G; Zhao, P P; Zhou, Y

    2002-01-01

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum K sub L (lambda sub L =3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged K sub L decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed.

  2. Learning in the context of distribution drift

    Science.gov (United States)

    2017-05-09

    AFRL-AFOSR-JP-TR-2017-0039 Learning in the context of distribution drift Geoff Webb MONASH UNIVERSITY Final Report 05/09/2017 DISTRIBUTION A...Department of Defense, Executive Services, Directorate (0704-0188).   Respondents should be aware that notwithstanding any other provision of law, no person ...23 Apr 2015 to 22 Apr 2017 4.  TITLE AND SUBTITLE Learning in the context of distribution drift 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1

  3. Shock drift mechanism for Forbush decreases

    Science.gov (United States)

    Cheng, Andrew F.; Sarris, E. T.; Dodopoulos, C.

    1990-01-01

    Consideration is given to the way in which Forbush decreases can arise from variable drifts in nonuniform shocks, where the variation in shock strength along the shock front causes both the shock drift distance and the energy gain to become variable. More particles can then be transported out of a given region of space and energy interval than were transported in, so a spacecraft passing through this region can observe a Forbush decrease in this energy interval despite shock energization and compression. A simple example of how this can occur is presented.

  4. Ultra-low mass drift chambers

    Energy Technology Data Exchange (ETDEWEB)

    Assiro, R. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Cappelli, L. [Università di Cassino e del Lazio Meridionale (Italy); Cascella, M. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento Matematica e Fisica, Università del Salento (Italy); De Lorenzis, L. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Grancagnolo, F. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Ignatov, F. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); L' Erario, A.; Maffezzoli, A. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Miccoli, A. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Onorato, G. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Università G. Marconi, Roma (Italy); Perillo, M. [EnginSoft S.p.a., Trento (Italy); Piacentino, G. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Fermilab, Batavia, IL (United States); Università G. Marconi, Roma (Italy); Rella, S. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Rossetti, F. [EnginSoft S.p.a., Trento (Italy); Spedicato, M. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Tassielli, G., E-mail: giovanni.tassielli@le.infn.it [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Università G. Marconi, Roma (Italy); and others

    2013-08-01

    We present a novel low mass drift chamber concept, developed in order to fulfill the stringent requirements imposed by the experiments for extremely rare processes, which require high resolutions (order of 100–200 keV/c) for particle momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution. We describe a geometry optimization procedure and a new wiring strategy with a feed-through-less wire anchoring system developed and tested on a drift chamber prototype under completion at INFN-Lecce.

  5. Experiencia a largo plazo con la operación de Ross en pacientes pediátricos

    Directory of Open Access Journals (Sweden)

    José M. Caffarena Calvar

    2008-07-01

    Conclusions: The Ross and Ross-Konno operations have changed the prognosis of pediatric patients with complex disease of the valve and aortic root. There is growth of the neo-aortic root in young patients. Sinotubular dilatation of the autograft with neoaortic valve insufficiency has been detected in patients with previously dilated aortic root when root replacement technique was performed. The best results are obtained in the younger andlower weight patients with complex left ventricular outflow obstruction without root dilatation. A close follow-up of patients with aortic root dilatation is mandatory to definitely validate the Ross procedure over aortic prosthesis.

  6. Effects of water depth and spectral bandwidth on Stokes drift estimation based on short-term variation of wave conditions

    Science.gov (United States)

    Myrhaug, Dag; Wang, Hong; Holmedal, Lars Erik

    2016-04-01

    The Stokes drift represents an important transport component of ocean circulation models. Locally it is responsible for transport of e.g. contaminated ballast water from ships, oil spills, plankton and larvae. It also plays an important role in mixing processes across the interphase between the atmosphere and the ocean. The Stokes drift is the mean Lagrangian velocity obtained from the water particle trajectory in the wave propagation direction; it is maximum at the surface, decreasing rapidly with the depth below the surface. The total mean mass transport is obtained by integrating the Stokes drift over the water depth; this is also referred to as the volume Stokes transport. The paper provides a simple analytical method which can be used to give estimates of the Stokes drift in moderate intermediate water depth based on short-term variation of wave conditions. This is achieved by using a joint distribution of individual wave heights and wave periods together with an explicit solution of the wave dispersion equation. The mean values of the surface Stokes drift and the volume Stokes transport for individual random waves within a sea state are presented, and the effects of water depth and spectral bandwidth parameter are discussed. Furthermore, example of results corresponding to typical field conditions are presented to demonstrate the application of the method, including the Stokes drift profile in the water column beneath the surface. Thus, the present analytical method can be used to estimate the Stokes drift in moderate intermediate water depth for random waves within a sea state based on available wave statistics.

  7. Austral Summer Sea Ice Melt Revealed in Antarctic ERS-1/2 and NSCAT Scatterometer Data

    Science.gov (United States)

    Drinkwater, M.; Liu, X.

    1999-01-01

    The first in-situ field observations of Antarcic austral summer sea-ice melt were made in the Bellingshausen Sea by Arctowski (1908) on Belgica in 1899, and later by Wordie (1921) during the ill-fated drift of Endurance in the Weddell Sea from 1914-1916.

  8. Austral Summer Sea Ice Melt Revealed in Antarctic ERS-1/2 and NSCAT Scatterometer Data

    Science.gov (United States)

    Drinkwater, M.; Liu, X.

    1999-01-01

    The first in-situ field observations of Antarcic austral summer sea-ice melt were made in the Bellingshausen Sea by Arctowski (1908) on Belgica in 1899, and later by Wordie (1921) during the ill-fated drift of Endurance in the Weddell Sea from 1914-1916.

  9. Effects of male removal on female reproductive biology in Ross' and Lesser Snow Geese

    Science.gov (United States)

    Leschack, C.R.; Afton, A.D.; Alisauskas, R.T.

    1998-01-01

    We studied effects of mate removal on nesting and hatching success, incubation behavior, body mass, and post-hatch dispersal distance of female Ross' (Chen rossii) and Lesser Snow Geese (C. caerulescens caerulescens) at Karrak Lake. N.W.T., Canada. Male ge and widowed and paired control females were monitored through post-hatch dispersal. Nesting and hatching success did not differ between species or treatments (widowed vs paired) and averaged 77.5 ?? 3.8% and 64.0 ?? 3.6% (??SE), respectively. Paired females spent more time with their bills tucked (23.7 ?? 3.3% vs 9.1 ?? 4.0%) and less time alert (8.6 ?? 2.9% vs 22.9 ?? 3.5%) while on nests than did widowed females. Snow widowed females (31.1 ?? 4.7%) and Ross' widowed females (20.6 ?? 6.0%) generally spent more time each day in head-up alert than did Snow paired females (7.1 ?? 3.8%). Snow paired maleS (11.8 ?? 3.8%), Ross' paired females (9.4 ?? 3.6%), and Ross' paired males (7.9 ?? 3.6%). Body mass of paired and widowed female Ross' Geese did not differ at hatch or at time of post-hatch recapture; however, mean distance recaptured from the breeding colony was greater for paired (50.9 ?? 6.1 km) than for widowed females (27.3 ?? 6.6 km). Total mass gain (276 ?? 19 g) and rate of mass gain (8.4 ?? 0.5 g/day), from hatch until post-hatch recapture (33.1 ?? 1.2 days), were similar for widowed and paired female Ross' Geese. Male removal experiments in monogamous, precocial species generally have produced few effects on female nesting success or incubation behavior. We suggest that male parental care in arctic-nesting geese is more critical during laying and the post-hatch period than during incubation.

  10. Psychometric Consequences of Subpopulation Item Parameter Drift

    Science.gov (United States)

    Huggins-Manley, Anne Corinne

    2017-01-01

    This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…

  11. Low-drift micro flow sensors

    NARCIS (Netherlands)

    Dijkstra, Marcel

    2009-01-01

    The emerging fields of micro total-analysis systems (micro-TAS), micro-reactors and bio-MEMS drives the need for further miniaturisation of sensors measuring quantities such as pressure, temperature and flow. The research described in this thesis concerns the development of low-drift micro flow sens

  12. Experimental design for drifting buoy Lagrangian test

    Science.gov (United States)

    Saunders, P. M.

    1975-01-01

    A test of instrumentation fabricated to measure the performance of a free drifting buoy as a (Lagrangian) current meter is described. Specifically it is proposed to distinguish between the trajectory of a drogued buoy and the trajectory of the water at the level of the drogue by measuring the flow relative to the drogue.

  13. Psychometric Consequences of Subpopulation Item Parameter Drift

    Science.gov (United States)

    Huggins-Manley, Anne Corinne

    2017-01-01

    This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…

  14. Ion Landau Damping on Drift Tearing Modes

    CERN Document Server

    Connor, J W; Zocco, A

    2012-01-01

    The equations governing the ion Landau damping (ILD) layers for a drift tearing mode are derived and solved to provide a matching to ideal MHD solutions at large $x$ and to the drift tearing solution emerging from the ion kinetic region, $k\\rho_{i}\\sim1$, at small $x,$ the distance from the rational surface. The ILD layers lie on either side of the mode rational surface at locations defined by $k_{y}xV_{Ti}/L_{s}=\\omega_{*e}(1+0.73\\eta_{e})$ and have been ignored in many previous analyses of linear drift tearing stability. The effect of the ILD layer on the drift tearing mode is to introduce an additional stabilizing contribution, requiring even larger values of the stability index, $\\Delta^{\\prime}$ for instability, than predicted by Connor Hastie and Zocco [PPCF,54, 035003, (2012)] and Cowley, Kulsrud and Hahm [Phys. Fluids,29, 3230, (1986)]. The magnitude and scaling of the new stabilizing effect in slab geometry is discussed.

  15. Stable discrete representation of relativistically drifting plasmas

    CERN Document Server

    Kirchen, Manuel; Godfrey, Brendan B; Dornmair, Irene; Jalas, Soeren; Peters, Kevin; Vay, Jean-Luc; Maier, Andreas R

    2016-01-01

    Representing the electrodynamics of relativistically drifting particle ensembles in discrete, co-propagating Galilean coordinates enables the derivation of a Particle-in-Cell algorithm that is intrinsically free of the Numerical Cherenkov Instability, for plasmas flowing at a uniform velocity. Application of the method is shown by modeling plasma accelerators in a Lorentz-transformed optimal frame of reference.

  16. Plate Tectonics and Continental Drift: Classroom Ideas.

    Science.gov (United States)

    Stout, Prentice K.

    1983-01-01

    Suggests various classroom studies related to plate tectonics and continental drift, including comments on and sources of resource materials useful in teaching the topics. A complete list of magazine articles on the topics from the Sawyer Marine Resource Collection may be obtained by contacting the author. (JN)

  17. Learning drifting concepts with neural networks

    NARCIS (Netherlands)

    Biehl, Michael; Schwarze, Holm

    1993-01-01

    The learning of time-dependent concepts with a neural network is studied analytically and numerically. The linearly separable target rule is represented by an N-vector, whose time dependence is modelled by a random or deterministic drift process. A single-layer network is trained online using differ

  18. Mode selective control of drift wave turbulence

    DEFF Research Database (Denmark)

    Schröder, C.; Klinger, T.; Block, D.;

    2001-01-01

    Experiments on spatiotemporal open-loop synchronization of drift wave turbulence in a magnetized cylindrical plasma are reported. The synchronization effect is modeled by a rotating current profile with prescribed mode structure. Numerical simulations of an extended Hasegawa-Wakatani model show g...

  19. Visualizing CMS muon drift tubes’ currents

    CERN Document Server

    Hamarik, Lauri

    2015-01-01

    This report documents my work as a summer student in the CMS DT group at CERN in July and August of 2015. During that time, I have participated in relocating DT monitoring experiment to GIF++ site and creating software to analyze drift tubes’ wires current dependence on luminosity and radioactivity.

  20. Drift wave launching in a linear quadrupole

    Energy Technology Data Exchange (ETDEWEB)

    Tessema, G.Y.; Elliott, J.A.; Rusbridge, M.G. (Manchester Univ. (UK). Inst. of Science and Technology)

    1989-12-01

    Drift waves have been successfully launched from flag probes in a steady-state magnetized plasma, and the launching mechanism has been identified. Non-linear interactions are observed between launched and intrinsic waves. A wide range of further experimental studies is thus made possible, of fundamental relevance to plasma confinement. (author).

  1. A large acceptance cylindrical drift chamber detector

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, D.A. [Texas Univ., Austin, TX (United States); Bachman, M.G. [Texas Univ., Austin, TX (United States); Coffey, W.P. [Texas Univ., Austin, TX (United States); Glass, G. [Texas Univ., Austin, TX (United States); McNaughton, K.H. [Texas Univ., Austin, TX (United States); Riley, P.J. [Texas Univ., Austin, TX (United States); Adams, D.L. [Rice University, Houston, TX 77251 (United States); Gaussiran, T.L. [Rice University, Houston, TX 77251 (United States); Hungerford, E.V. [University of Houston, Houston, TX 77204 (United States); Lan, K.A. [University of Houston, Houston, TX 77204 (United States); Johnston, K. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); McNaughton, M.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Penttila, S.I. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Supek, I. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    1995-10-01

    This paper describes a large acceptance cylindrical drift chamber detector designed and built for the study of the np{yields}pp{pi}{sup -} reaction at neutron beam energies in the range 500-800 MeV. Details of construction, electronics, testing, and detection efficiencies and resolutions are presented. (orig.).

  2. Stochastic Evolution Equations with Adapted Drift

    NARCIS (Netherlands)

    Pronk, M.

    2013-01-01

    In this thesis we study stochastic evolution equations in Banach spaces. We restrict ourselves to the two following cases. First, we consider equations in which the drift is a closed linear operator that depends on time and is random. Such equations occur as mathematical models in for instance

  3. Effects of Drifting Macroalgae in Eelgrass Ecosystems

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Valdemarsen, Thomas Bruun; Kristensen, Erik

    2010-01-01

    and physical damage on eelgrass can occur when macroalgae are drifting as bedload. The ballistic effect of moving macroalgae on surface sediment was tested in the field as well as in a series of annular flume experiments, where simultaneous measurements of macroalgae transport and turbidity were measured...

  4. Effects of Drifting Macroalgae in Eelgrass Ecosystems

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Valdemarsen, Thomas Bruun; Kristensen, Erik

    2010-01-01

    It has been suggested that current-driven macroalge transport in shallow lagoons and estuaries may negatively impact eelgrass through increased turbidity and physical stress. Increased turbidity and lower light availability for eelgrass may result when drifting macroalgae erode surface sediment a...

  5. Generalization of the one dimensional modeling and design considerations of spiral Si drift detectors: Flat (straight) drift channels and constant drift fields

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Manwen, E-mail: mwliu1993@163.com; Li, Zheng, E-mail: zhengli58@gmail.com

    2016-07-11

    The one-dimensional design consideration for the spiral (cylindrical geometry) Si drift detector (SDD) has been modified and generalized for small drift distance (R) compatible to the detector thickness (d), i.e. for R–d, and for non uniform backside biasing situations. By applying a non uniform biasing voltage with a gradient similar (proportional) to the front side, one can increase the reach-through voltage, resulting in a large drift field for carriers. This can be important for large R (>3 mm). With a careful design of electric field profiles on both sides, one can obtain the optimum case of a spiral SDD with a straight (flat) drift channel and constant drift field throughout the carrier drift channel. The previous solution in the literature is an approximation of this work for R»d and with a curved drift channel.

  6. Generalization of the one dimensional modeling and design considerations of spiral Si drift detectors: Flat (straight) drift channels and constant drift fields

    Science.gov (United States)

    Liu, Manwen; Li, Zheng

    2016-07-01

    The one-dimensional design consideration for the spiral (cylindrical geometry) Si drift detector (SDD) has been modified and generalized for small drift distance (R) compatible to the detector thickness (d), i.e. for R-d, and for non uniform backside biasing situations. By applying a non uniform biasing voltage with a gradient similar (proportional) to the front side, one can increase the reach-through voltage, resulting in a large drift field for carriers. This can be important for large R (>3 mm). With a careful design of electric field profiles on both sides, one can obtain the optimum case of a spiral SDD with a straight (flat) drift channel and constant drift field throughout the carrier drift channel. The previous solution in the literature is an approximation of this work for R»d and with a curved drift channel.

  7. Antarctic sea-ice expansion between 2000 and 2014 driven by tropical Pacific decadal climate variability

    Science.gov (United States)

    Meehl, Gerald A.; Arblaster, Julie M.; Bitz, Cecilia M.; Chung, Christine T. Y.; Teng, Haiyan

    2016-08-01

    Antarctic sea-ice extent has been slowly increasing in the satellite record that began in 1979. Since the late 1990s, the increase has accelerated, but the average of all climate models shows a decline. Meanwhile, the Interdecadal Pacific Oscillation, an internally generated mode of climate variability, transitioned from positive to negative, with an average cooling of tropical Pacific sea surface temperatures, a slowdown of the global warming trend and a deepening of the Amundsen Sea Low near Antarctica that has contributed to regional circulation changes in the Ross Sea region and expansion of sea ice. Here we show that the negative phase of the Interdecadal Pacific Oscillation in global coupled climate models is characterized by anomalies similar to the observed sea-level pressure and near-surface 850 hPa wind changes near Antarctica since 2000 that are conducive to expanding Antarctic sea-ice extent, particularly in the Ross Sea region in all seasons, involving a deepening of the Amundsen Sea Low. These atmospheric circulation changes are shown to be mainly driven by precipitation and convective heating anomalies related to the Interdecadal Pacific Oscillation in the equatorial eastern Pacific, with additional contributions from convective heating anomalies in the South Pacific convergence zone and tropical Atlantic regions.

  8. High resolution modelling of the decreasing Arctic sea ice

    DEFF Research Database (Denmark)

    Madsen, K. S.; Rasmussen, T. A. S.; Blüthgen, Jonas

    2012-01-01

    The Arctic sea ice cover has been rapidly decreasing and thinning over the last decade, with minimum ice extent in 2007 and almost as low extent in 2011. This study investigates two aspects of the decreasing ice cover; first the large scale thinning and changing dynamics of the polar sea ice......, and secondly oceanic oil drift in ice affected conditions. Both investigations are made with the coupled ocean - sea ice model HYCOM-CICE at 10 km resolution, which is also used operationally at DMI and allows detailed studies of sea ice build-up, drift and melt. To investigate the sea ice decrease of the last...... and changing dynamics and discuss how they relate to satellite observations. The relation to the upper ocean heat content is also investigated. The decreasing sea ice has opened up for increased ship traffic and oil exploration in the polar oceans. To avoid damage on the pristine Arctic ecosystem...

  9. High resolution modelling of the decreasing Arctic sea ice

    DEFF Research Database (Denmark)

    Madsen, K. S.; Rasmussen, T. A. S.; Blüthgen, Jonas

    2012-01-01

    , and secondly oceanic oil drift in ice affected conditions. Both investigations are made with the coupled ocean - sea ice model HYCOM-CICE at 10 km resolution, which is also used operationally at DMI and allows detailed studies of sea ice build-up, drift and melt. To investigate the sea ice decrease of the last......The Arctic sea ice cover has been rapidly decreasing and thinning over the last decade, with minimum ice extent in 2007 and almost as low extent in 2011. This study investigates two aspects of the decreasing ice cover; first the large scale thinning and changing dynamics of the polar sea ice...... decade, we have performed a reanalysis simulation of the years 1990-2011, forced with ERA Interim atmospheric data. Thus, the simulation includes both the period before the recent sea ice decrease and the full period of decrease up till today. We will present our model results of the thinning...

  10. Drifting algal mats as an alternative habitat for benthic invertebrates: Species specific responses to a transient resource.

    Science.gov (United States)

    Norkko; Bonsdorff; Norkko

    2000-05-18

    Patchy occurrences of benthic drift algae (i.e. loose lying macroalgal mats) may increase habitat complexity on normally bare soft bottoms, but at the same time, extensive amounts of drifting algal mats are known to stress the benthic fauna. This paper presents results of the first detailed study of the fauna associated with drift algal mats in the northern Baltic Sea. In order to assess the importance of drifting algae as an alternative habitat for benthic fauna, benthic drift algal mats were sampled on shallow (2-9 m) sandy soft bottoms in the outer archipelago of the Åland Islands (Finland). Species composition, abundance and biomass of the macrofauna associated with algal mats were recorded. The results show that drifting algae at times can harbour very high abundances of invertebrates (up to 1116 individuals/g algal dryweight), surpassing invertebrate densities recorded in seagrass communities. The algal fauna varied between sites and over time, and factors such as ambient benthic fauna, exposure to wind-wave disturbance, depth, and algal coverage and condition influenced the invertebrate community composition of the algal mats. Abundance increased while individual biomass of the animals decreased over time (summer season; July-October). A series of laboratory experiments were conducted in order to test the ability of a few important benthic species to move up into, and survive in a drifting algal mat. Macoma balthica, Hydrobia spp., Nereis diversicolor and Bathyporeia pilosa were used in the experiments, and significant differences in their survival and mobility within drifting algae were recorded. This study shows that benthic species differ significantly in their ability to utilise the algal mats, with mainly opportunistic and mobile taxa such as Hydrobia spp., Chironomidae and Ostracoda benefiting from the algae, whereas infaunal species such as M. balthica and B. pilosa are negatively affected. The occurrence of eutrophication induced drifting macroalgal

  11. Competition and Concentration in Bangladeshi Banking Sector: An Application of Panzar-Rosse Model

    Directory of Open Access Journals (Sweden)

    Md. Anwar Hossain Repon

    2016-01-01

    Full Text Available The purpose of this paper is to investigate the market structure and degree of concentration of Bangladeshi banking industry. The study measured market concentration by using widely recognized measures like k-bank concentration ratio and Herfindahl-Hirchman Index (HHI. It evaluates market structure by applying Panzar-Rosse Model over 8 years period from 2006 to 2013. The result of concentration measures indicates a decreasing trend and low level of market concentration in Bangladeshi banking industry over the sample period. The panzer-Rosse “H-Statistic” suggests that banks in Bangladesh are operating under monopolistic competition. Present paper contributes to a burgeoning literature on banking competition that has evolved significantly over the past periods on a developing country perspective like Bangladesh.

  12. Percutaneous valved stent repair of a failed homograft: implications for the Ross procedure.

    Science.gov (United States)

    Pretorius, Victor; Jones, Alan; Taylor, Dylan; Coe, Yashu; Ross, David B

    2008-08-01

    A case of percutaneous pulmonary valve implantation following a failed homograft in the pulmonary position is reported. A 16-year-old boy developed infective endocarditis of his pulmonary homograft, which was implanted four years earlier during a Ross procedure for congenital aortic stenosis. Following successful medical therapy, the boy was symptomatic due to pulmonary stenosis and regurgitation. A 22 mm Melody valve (Medtronic, USA) was successfully implanted percutaneously. His symptoms resolved and he was discharged home one day after the procedure. Echocardiography at the six-month follow-up demonstrated a normally functioning pulmonary valve. Percutaneous pulmonary valve replacement may make the Ross procedure a more attractive option for patients with aortic stenosis, particularly in the pediatric population.

  13. ROSS Video:摄像机机器人云台隆重登场BIRTV

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    ROSS Video作为一家拥有40年历史的广播电视设备制造厂商,在2012年取得了令人振奋的突破性增长。随着全球市场占有率的不断提高,今年早些时候ROSS分别完成了对比利时FX—Motion和美国Cambotics两家机器人摄像机跟踪遥控系统公司的收购,并成立了全新的ROSS Robotics部门,进一步扩展了其原有产品体系,为客户带来更丰富、更完整的视频制作解决方案。

  14. A Battle of Words: "Dignity" and "Peace" in the Writings of Elisabeth Kübler-Ross.

    Science.gov (United States)

    Burnier, Daniel

    2017-01-01

    This article analyzes the writings of Elisabeth Kübler-Ross through the discursive lens of the phrase "dying with dignity." For her, the phrase meant allowing someone to die comfortably his/her own death. This phrase has to be understood in relationship with the final "stage of acceptance" of her model. Describing this key part of her well-known scientific output, she often used, in the early 1970s, the phrase "dying in peace and dignity." An evaluation of the evidence suggests that because the concept of dignity was co-opted by the pro-euthanasia movement during this decade, the language of dignity was little by little abandoned by her. In later years, only "peace" survived from her favorite expression. Although this concept of peace remains present to the end in all Kübler-Ross writings, the pro-euthanasia movement has also started to speak the language of peace.

  15. Barber's Point, Oahu, Hawaii Drift Card Study 2002-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drift cards were be released from Barber's Point, Oahu, approximately once a month during the two year span to get an idea of the distribution of card drift under...

  16. Exploring Genetic Drift and Natural Selection through a Simulation Activity.

    Science.gov (United States)

    Maret, Timothy J.; Rissing, Steven W.

    1998-01-01

    Reports on the development of a laboratory exercise that would allow students to explore the concept of genetic drift. Discusses the concept of genetic drift that is coincident with natural selection and that closely models the real world. (DDR)

  17. Drift-Scale THC Seepage Model

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Bryan

    2005-02-17

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral

  18. From warm to cold: migration of Adélie penguins within Cape Bird, Ross Island

    OpenAIRE

    Yaguang Nie; Liguang Sun; Xiaodong Liu; Emslie, Steven D.

    2015-01-01

    Due to their sensitivity to environmental change, penguins in Antarctica are widely used as bio-indicators in paleoclimatic research. On the basis of bio-element assemblages identified in four ornithogenic sediment profiles, we reconstructed the historical penguin population change at Cape Bird, Ross Island, for the past 1600 years. Clear succession of penguin population peaks were observed in different profiles at about 1400 AD, which suggested a high probability of migration within this reg...

  19. Ross syndrome with ANA positivity: A clue to possible autoimmune origin and treatment with intravenous immunoglobulin

    Directory of Open Access Journals (Sweden)

    Vasudevan Biju

    2010-01-01

    Full Text Available A 28-year-old serving soldier presented with patchy areas of absence of sweating and blurring of vision. On examination he was found to have segmental anhidrosis, right sided tonic pupil and absent ankle jerks. Investigations revealed ANA positivity with no other abnormalities. He was treated with Intravenous immunoglobulin. This case of Ross syndrome is reported for its rarity as well as a clue to its probable autoimmune origin and treatment option with intravenous immunoglobulins.

  20. Climate variation and incidence of Ross river virus in Cairns, Australia: a time-series analysis.

    OpenAIRE

    Tong, S; Hu, W.

    2001-01-01

    In this study we assessed the impact of climate variability on the Ross River virus (RRv) transmission and validated an epidemic-forecasting model in Cairns, Australia. Data on the RRv cases recorded between 1985 and 1996 were obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. The cross-correlation function (CCF) showed that maximum temperature in the curren...