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Sample records for shelf water cascading

  1. Major consequences of an intense dense shelf water cascading event on deep-sea benthic trophic conditions and meiofaunal biodiversity

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    A. Pusceddu

    2013-04-01

    Full Text Available Numerous submarine canyons around the world are preferential conduits for episodic dense shelf water cascading (DSWC, which quickly modifies physical and chemical ambient conditions while transporting large amounts of material towards the base of slope and basin. Observations conducted during the last 20 yr in the Lacaze-Duthiers and Cap de Creus canyons (Gulf of Lion, NW Mediterranean Sea report several intense DSWC events. The effects of DSWC on deep-sea ecosystems are almost unknown. To investigate the effects of these episodic events, we analysed changes in the meiofaunal biodiversity inside and outside the canyon. Sediment samples were collected at depths varying from ca. 1000 to > 2100 m in May 2004 (before a major event, April 2005 (during a major cascading event and in October 2005, August 2006, April 2008 and April 2009 (after a major event. We report here that the late winter–early spring 2005 cascading led to a reduction of the organic matter contents in canyon floor sediments down to 1800 m depth, whereas surface sediments at about 2200 m depth showed an increase. Our findings suggest that the nutritional material removed from the shallower continental shelf, canyon floor and flanks, and also the adjacent open slope was rapidly transported to the deep margin. During the cascading event the meiofaunal abundance and biodiversity in the studied deep-sea sediments were significantly lower than after the event. Benthic assemblages during the cascading were significantly different from those in all other sampling periods in both the canyon and deep margin. After only six months from the cessation of the cascading, benthic assemblages in the impacted sediments were again similar to those observed in other sampling periods, thus illustrating a quick recovery. Since the present climate change is expected to increase the intensity and frequency of these episodic events, we anticipate that they will increasingly affect benthic bathyal

  2. Dense shelf water cascading in the northwestern Mediterranean during the cold winter 2005: Quantification of the export through the Gulf of Lion and the Catalan margin

    NARCIS (Netherlands)

    Ulses, C.; Estournel, C.; Puig, P.; Durrieu de Madron, X.; Marsaleix, P.

    2008-01-01

    Dense shelf water cascading in the northwestern Mediterranean Sea during winter 2005, which was shown to cause large erosion in the canyons and to influence deep benthic ecosystem, was investigated using numerical modeling validated with temperature and current observations. Intense dense water

  3. Cascading off the West Greenland Shelf: A numerical perspective

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    Marson, Juliana M.; Myers, Paul G.; Hu, Xianmin; Petrie, Brian; Azetsu-Scott, Kumiko; Lee, Craig M.

    2017-07-01

    Cascading of dense water from the shelf to deeper layers of the adjacent ocean basin has been observed in several locations around the world. The West Greenland Shelf (WGS), however, is a region where this process has never been documented. In this study, we use a numerical model with a 1/4° resolution to determine (i) if cascading could happen from the WGS; (ii) where and when it could take place; (iii) the forcings that induce or halt this process; and (iv) the path of the dense plume. Results show cascading happening off the WGS at Davis Strait. Dense waters form there due to brine rejection and slide down the slope during spring. Once the dense plume leaves the shelf, it gradually mixes with waters of similar density and moves northward into Baffin Bay. Our simulation showed events happening between 2003-2006 and during 2014; but no plume was observed in the simulation between 2007 and 2013. We suggest that the reason why cascading was halted in this period is related to: the increased freshwater transport from the Arctic Ocean through Fram Strait; the additional sea ice melting in the region; and the reduced presence of Irminger Water at Davis Strait during fall/early winter. Although observations at Davis Strait show that our simulation usually overestimates the seasonal range of temperature and salinity, they agree with the overall variability captured by the model. This suggests that cascades have the potential to develop on the WGS, albeit less dense than the ones estimated by the simulation.

  4. Sediment transport processes at the head of Halibut Canyon, Eastern Canada margin: An interplay between internal tides and dense shelf water cascading.

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    Puig, Pere; Greenan, Blair J. W.; Li, Michael Z.; Prescott, Robert H.; Piper, David J. W.

    2013-04-01

    To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008-2009. Two main sediment transport processes were identified throughout the deployment. Firstly, periodic increases of near-bottom suspended-sediment concentrations (SSC) were recorded associated with the up-canyon propagation of the semidiurnal internal tidal bore along the canyon axis, carrying fine sediment particles resuspended from deeper canyon regions. The recorded SSC peaks, lasting less than one hour, were observed sporadically and were linked to bottom intensified up-canyon flows concomitant with sharp drops in temperature. Secondly, sediment transport was also observed during events of intensified down-canyon current velocities that occurred during periods of sustained heat loss from surface waters, but were not associated with large storms. High-resolution velocity profiles throughout the water column during these events revealed that the highest current speeds (~1 m s-1) were centered several meters above the sea floor and corresponded to the region of maximum velocities of a gravity flow. Such flows had associated low SSC and cold water temperatures and have been interpreted as dense shelf water cascading events channelized along the canyon axis. Sediment transport during these events was largely restricted to bedload and saltation, producing winnowing of sands and fine sediments around larger gravel particles. Analysis of historical hydrographic data suggests that the origin of such gravity flows is not related to the formation of coastal dense waters advected towards the canyon head. Rather, the dense shelf waters appear to be generated around the outer shelf, where convection during winter is able to reach the sea floor and generate a pool of near-bottom dense water that cascades into the canyon

  5. Water masses of Visakhapatnam shelf

    Digital Repository Service at National Institute of Oceanography (India)

    RamaRaju, V.S.; Sarma, V.V.; Rao, B.P.; Rao, V.S.

    The T-S relationships of shelf waters off Visakhapatnam in the Bay of Bengal are studied for the different seasons with the data collected during February 1979 to January 1981. The T-S relationships indicate distinct characteristics of the water...

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

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    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.

  7. Trace metal fronts in European shelf waters

    International Nuclear Information System (INIS)

    Kremling, K.

    1983-01-01

    The Hebrides shelf edge area is characterized by strong horizontal salinity gradients (fronts) which mark the boundary between Scottish coastal and oceanic waters. The results presented here, obtained in summer 1981 on a transect between the open north Atlantic and the German Bight, confirm that the hydrographical front is accompanied by dramatic increases in inorganic nutrients (phosphate, silicate) and dissolved trace elements such as Cd, Cu, Mn, and 226 Ra. These data (together with measurements from North Sea regions) suggest that the trace metals are mobilized from partly reduced (organic-rich) sediments and vertically mixed into the surface waters. The regional variations evident from the transect are interpreted as being the result of the hydrography prevailing in waters around the British Isles. (author)

  8. Cyclonic entrainment of preconditioned shelf waters into a frontal eddy

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    Everett, J. D.; Macdonald, H.; Baird, M. E.; Humphries, J.; Roughan, M.; Suthers, I. M.

    2015-02-01

    The volume transport of nutrient-rich continental shelf water into a cyclonic frontal eddy (entrainment) was examined from satellite observations, a Slocum glider and numerical simulation outputs. Within the frontal eddy, parcels of water with temperature/salinity signatures of the continental shelf (18-19°C and >35.5, respectively) were recorded. The distribution of patches of shelf water observed within the eddy was consistent with the spiral pattern shown within the numerical simulations. A numerical dye tracer experiment showed that the surface waters (≤50 m depth) of the frontal eddy are almost entirely (≥95%) shelf waters. Particle tracking experiments showed that water was drawn into the eddy from over 4° of latitude (30-34.5°S). Consistent with the glider observations, the modeled particles entrained into the eddy sunk relative to their initial position. Particles released south of 33°S, where the waters are cooler and denser, sunk 34 m deeper than their release position. Distance to the shelf was a critical factor in determining the volume of shelf water entrained into the eddy. Entrainment reduced to 0.23 Sv when the eddy was furthest from the shelf, compared to 0.61 Sv when the eddy was within 10 km of the shelf. From a biological perspective, quantifying the entrainment of shelf water into frontal eddies is important, as it is thought to play a significant role in providing an offshore nursery habitat for coastally spawned larval fish.

  9. Formation waters of the Norwegian Continental Shelf

    Energy Technology Data Exchange (ETDEWEB)

    McCartney, R. A.; Rein, E.

    2006-03-15

    New and previously published analyses of formation waters for the Norwegian Continental Shelf (NCS) have been evaluated and interpreted to determine the compositional distribution of formation waters in the region and factors controlling their compositions, and also to obtain information on subsurface fluid flow. Formation waters in the region are Na-Cl and Na-Ca-Cl-type waters that display a wide range of salinity (2500-212000 mg/kg Cl). Generally, the concentrations of most dissolved constituents are positively correlated with Cl so that their distribution in formation waters largely reflects the variations shown by salinity. Exceptions are SO4 which is generally low (less than 40 mg/l) regardless of Cl, and HCO3 and in-situ pH which are negatively correlated with Cl. The main factors determining the compositions of the formation waters are mixing of meteoric water (probably late-Jurassic to Eocene), ancient seawater and primary brine together with diagenetic reactions that have affected each of these components individually as well as mixtures of them. Evaluation of the distribution of salinity has helped us identify where vertical and/or lateral migration of brine from the evaporites has occurred. This has in turn provided us with information on the presence of leak-points and vertical mixing, although further investigation of the location of evaporites and basin palaeohydrogeology are required to determine whether regional lateral advection has occurred in the past. The results of this study may benefit oil exploration and production activities in the NCS including constraint of hydrocarbon migration models, economic evaluation of undrilled prospects, scale management and compartmentalisation studies. (Author)

  10. Climatology and decadal variability of the Ross Sea shelf waters

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    A. Russo

    2011-06-01

    Full Text Available The World Ocean Database 2001 data located in the Ross Sea (named WOD01 and containing data in this region since 1928 are merged with recent data collected by the Italian expeditions (CLIMA dataset in the period November 1994-February 2004 in the same area. From this extended dataset, austral summer climatologies of the main Ross Sea subsurface, intermediate and bottom water masses: High Salinity Shelf Water (HSSW, Low Salinity Shelf Water (LSSW, Ice Shelf Water (ISW and Modified Circumpolar Deep Water (MCDW have been drawn. The comparison between the WOD01_1994 climatologies (a subset of the WOD01 dataset until April 1994 and the CLIMA ones for the period 1994/95-2003/04 showed significant changes occurred during the decade. The freshening of the Ross Sea shelf waters which occurred during the period 1960-2000, was confirmed by our analysis in all the main water masses, even though with a spatially varying intensity. Relevant variations were found for the MCDW masses, which appeared to reduce their presence and to deepen; this can be ascribed to the very limited freshening of the MCDW core, which allowed an increased density with respect to the surrounding waters. Variations in the MCDW properties and extension could have relevant consequences, e.g. a decreased Ross Ice Shelf basal melting or a reduced supply of nutrients, and may also be indicative of a reduced thermohaline circulation within the Ross Sea. Shelf Waters (SW having neutral density γn > 28.7 Kg m-3, which contribute to form the densest Antarctic Bottom Waters (AABW, showed a large volumetric decrease in the 1994/95-2003/04 decade, most likely as a consequence of the SW freshening.

  11. Identification of cascade water tanks using a PWARX model

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    Mattsson, Per; Zachariah, Dave; Stoica, Petre

    2018-06-01

    In this paper we consider the identification of a discrete-time nonlinear dynamical model for a cascade water tank process. The proposed method starts with a nominal linear dynamical model of the system, and proceeds to model its prediction errors using a model that is piecewise affine in the data. As data is observed, the nominal model is refined into a piecewise ARX model which can capture a wide range of nonlinearities, such as the saturation in the cascade tanks. The proposed method uses a likelihood-based methodology which adaptively penalizes model complexity and directly leads to a computationally efficient implementation.

  12. Strontium 90 in silts of the Dnieper cascade water reservoirs

    International Nuclear Information System (INIS)

    Romanenko, V.D.; Kuz'menko, M.I.; Matvienko, L.P.; Klenus, V.G.; Nasvit, O.I.

    1989-01-01

    The change of strontium-90 content in water and silts of the Dnieper cascade water reservoirs was analyzed. It was shown, that decrease of strontium-90 content in water in time connected basically with ion exchange adsorption of strontium-90 by residues. A high sorption ability of residues made it possible for radioisotopes to reduce sharply their concentration along depth of soils. The highest concentration of radioisotopes was in the upper layers, enriched by silt. It was ascertained, that strontium-90 migration along depth of residues took place rapidly in the Kiev's water reservoir. Down the cascade strontium-90 content reduced in lower layers of residues as well as in upper layers. 4 tabs

  13. Node vulnerability of water distribution networks under cascading failures

    International Nuclear Information System (INIS)

    Shuang, Qing; Zhang, Mingyuan; Yuan, Yongbo

    2014-01-01

    Water distribution networks (WDNs) are important in modern lifeline system. Its stability and reliability are critical for guaranteeing high living quality and continuous operation of urban functions. The aim of this paper is to evaluate the nodal vulnerability of WDNs under cascading failures. Vulnerability is defined to analyze the effects of the consequent failures. A cascading failure is a step-by-step process which is quantitatively investigated by numerical simulation with intentional attack. Monitored pressures in different nodes and flows in different pipes have been used to estimate the network topological structure and the consequences of nodal failure. Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. A load variation function is established to record the nodal failure reason and describe the relative differences between the load and the capacity. The proposed method is validated by an illustrative example. The results revealed that the network vulnerability should be evaluated with the consideration of hydraulic analysis and network topology. In the case study, 70.59% of the node failures trigger the cascading failures with different failure processes. It is shown that the cascading failures result in severe consequences in WDNs. - Highlights: • The aim of this paper is to evaluate the nodal vulnerability of water distribution networks under cascading failures. • Monitored pressures and flows have been used to estimate the network topological structure and the consequences of nodal failure. • Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. • A load variation function is established to record the failure reason and describe the relative differences between load and capacity. • The results show that 70.59% of the node failures trigger the cascading failures with different failure processes

  14. The relationship between phytoplankton distribution and water column characteristics in North West European shelf sea waters.

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    Fehling, Johanna; Davidson, Keith; Bolch, Christopher J S; Brand, Tim D; Narayanaswamy, Bhavani E

    2012-01-01

    Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf seas are poorly understood. To begin to address this in North Western European waters, the phytoplankton community composition was assessed in light of measured physical and chemical drivers during the "Ellett Line" cruise of autumn 2001 across the Scottish Continental shelf and into adjacent open Atlantic waters. Spatial variability existed in both phytoplankton and environmental conditions, with clear differences not only between on and off shelf stations but also between different on shelf locations. Temperature/salinity plots demonstrated different water masses existed in the region. In turn, principal component analysis (PCA), of the measured environmental conditions (temperature, salinity, water density and inorganic nutrient concentrations) clearly discriminated between shelf and oceanic stations on the basis of DIN:DSi ratio that was correlated with both salinity and temperature. Discrimination between shelf stations was also related to this ratio, but also the concentration of DIN and DSi. The phytoplankton community was diatom dominated, with multidimensional scaling (MDS) demonstrating spatial variability in its composition. Redundancy analysis (RDA) was used to investigate the link between environment and the phytoplankton community. This demonstrated a significant relationship between community composition and water mass as indexed by salinity (whole community), and both salinity and DIN:DSi (diatoms alone). Diatoms of the Pseudo-nitzschia seriata group occurred at densities potentially harmful to shellfish aquaculture, with the potential for toxicity being elevated by the likelihood of DSi limitation of

  15. The relationship between phytoplankton distribution and water column characteristics in North West European shelf sea waters.

    Directory of Open Access Journals (Sweden)

    Johanna Fehling

    Full Text Available Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf seas are poorly understood. To begin to address this in North Western European waters, the phytoplankton community composition was assessed in light of measured physical and chemical drivers during the "Ellett Line" cruise of autumn 2001 across the Scottish Continental shelf and into adjacent open Atlantic waters. Spatial variability existed in both phytoplankton and environmental conditions, with clear differences not only between on and off shelf stations but also between different on shelf locations. Temperature/salinity plots demonstrated different water masses existed in the region. In turn, principal component analysis (PCA, of the measured environmental conditions (temperature, salinity, water density and inorganic nutrient concentrations clearly discriminated between shelf and oceanic stations on the basis of DIN:DSi ratio that was correlated with both salinity and temperature. Discrimination between shelf stations was also related to this ratio, but also the concentration of DIN and DSi. The phytoplankton community was diatom dominated, with multidimensional scaling (MDS demonstrating spatial variability in its composition. Redundancy analysis (RDA was used to investigate the link between environment and the phytoplankton community. This demonstrated a significant relationship between community composition and water mass as indexed by salinity (whole community, and both salinity and DIN:DSi (diatoms alone. Diatoms of the Pseudo-nitzschia seriata group occurred at densities potentially harmful to shellfish aquaculture, with the potential for toxicity being elevated by the likelihood of DSi

  16. Imprudent fishing harvests and consequent trophic cascades on the West Florida shelf over the last half century: A harbinger of increased human deaths from paralytic shellfish poisoning along the southeastern United States, in response to oligotrophication?

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    Walsh, J. J.; Tomas, C. R.; Steidinger, K. A.; Lenes, J. M.; Chen, F. R.; Weisberg, R. H.; Zheng, L.; Landsberg, J. H.; Vargo, G. A.; Heil, C. A.

    2011-06-01

    Within the context of ubiquitous overfishing of piscivores, recent consequent increments of jellyfish and clupeids have occurred at the zooplanktivore trophic level in the eastern Gulf of Mexico (GOM), after overfishing of one of their predators, i.e. red snapper. Initiation of a local trophic cascade thence led to declines of herbivore stocks, documented here on the West Florida shelf. These exacerbating world-wide trophic cascades have resulted in larger harmful algal blooms (HABs), already present at the base of most coastal food webs. Impacts on human health have thus far been minimal within nutrient-rich coastal regions. To provide a setting for past morbidities, consideration is given to chronologies of other trophic cascades within eutrophic, cold water marine ecosystems of the Scotian Sea, in the Gulf of Alaska, off Southwest Africa, within the Barents, White, and Black Seas, in the Gulf of Maine, and finally in the North Sea. Next, comparison is now made here of recent ten-fold increments within Florida waters of both relatively benign and saxitoxic HABs, some of which are fatal to humans. These events are placed in a perspective of other warm shelf systems of the South China and Caribbean Seas to assess prior and possible future poison toxicities of oligotrophic coastal habitats. Past wide-spread kills of fishes and sea urchins over the Caribbean Sea and the downstream GOM are examined in relation to the potential transmission of dinoflagellate saxitoxin and other epizootic poison vectors by western boundary currents over larger "commons" than local embayments. Furthermore, since some HABs produce more potent saxitoxins upon nutrient depletion, recent decisions to ban seasonal fertilizer applications to Florida lawns may have unintended consequences. In the future, human-killing phytoplankton, rather than relatively benign fish-killing HABs of the past, may be dispersed along the southeastern United States seaboard.

  17. Cascading of high salinity bottom waters from the Arabian/Persian Gulf to the northern Arabian Sea

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    Shapiro, Georgy; Wobus, Fred; Solovyev, Vladimir; Francis, Xavier; Hyder, Patrick; Chen, Feng; Asif, Muhammad

    2017-04-01

    Cascading (aka shelf convection) is a specific type of buoyancy driven current in which dense water is formed over the continental shelf and then descends down the slope to a greater depth. The cascades of dense water down continental slopes provide a mechanism for shelf-ocean exchange in many parts of the world's oceans (Shapiro et al, 2003). Dense water is formed on the shelf by a number of processes, with high evaporation, limited river discharge and low precipitation being the major processes in warm climates (Ivanov et al, 2004). The formation and outflow of high salinity waters in the near-bottom layer of the Arabian/Persian Gulf is an example of dense water cascading (Bower et al 2000). Despite of its importance for the self-cleaning and the state of the marine ecosystem in the Arabian/Persian Gulf, the properties of the outflow have so far mainly been analysed using climatologically averaged data or observations of a limited set of parameters (mainly temperature), see (Bower et al 2000). In this paper we study the dynamics of the flow using a comprehensive set of observational data (temperature, salinity velocity and turbidity profiles) obtained during the GRASP (Gulf Reconnaissance And Selective Profiling) observational campaign in the Gulf of Oman, which are complemented by the results of numerical modelling of the area using a number of 3D ocean models, and some ARGO T/S profiles. The GRASP measurements were carried out using an Aqualog climbing moored profiler, which was equipped with a Seabird CTD sensor, a Nortek Aquadopp current meter and a Seapoint turbidity meter. The Ocean circulation models used in the study include PGM4 and IND12 (UK Met Office); and AS20 and AG60 (University of Plymouth). All models are based on NEMO (Nucleus for European Modelling of the Ocean) codebase with a resolution from 9 km down to 1.8 km. The models were calibrated and validated against ARGO float profiles in the area. The study revealed the mesoscale and sub

  18. DECREASING OF WATER TROPHY IN CASCADE SYSTEMS, ON EXAMPLE OF THE SOŁA RIVER DAM CASCADE (SOUTHERN POLAND

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    Ewa Jachniak

    2014-10-01

    Full Text Available In this thesis the subject of water self-purification in cascade systems of water reservoirs was engaged. The results of hydrobiological research of three dam reservoirs (Tresna, Porąbka and Czaniec, creating the Soła river dam cascade were presented. The trophic status of these reservoirs was defined on the grounds of the concentration of chlorophyll a, biomass of phytoplankton and occurrence of indicating species of planktonic algae. The results of research indicated on decreasing of water trophy in the layout from the highest into the lowest reservoir of the cascade. The average concentrations of chlorophyll a amounted appropriately 19,99 μg·dm-3, 8,74 μg·dm-3 and 4,29 μg·dm-3, instead the average biomass of phytoplankton amounted appropriately 4,1 mg·dm-3, 3,4 mg·dm-3 and 0,1 mg·dm-3. The observed species of algae confirmed occurrence of differences between reservoirs. In Tresna reservoir more species of phytoplankton indicating for eutrophy were thrived, instead in Porąbka and Czaniec reservoirs the species occurring in oligomesotrophic water thrived. Water self-purification in the Soła river dam cascade expressed decreasing of their fertility is important for water management of the region, because the Czaniec reservoir fulfill a function of water-supply reservoir.

  19. Transport and transfer rates in the waters of the continental shelf and slope: SEEP

    International Nuclear Information System (INIS)

    Biscaye, P.E.; Anderson, R.F.

    1993-01-01

    The overall Shelf Edge Exchange Processes (SEEP) Program, which began in 1980 or 1981, had as its goal the testing of a hypothesis with respect to the fate of particulate matter formed in and introduced into the waters of the continental shelf adjacent to the northern east coast of the US, i.e., the MAB. The original hypothesis was that a large proportion of the particles in general, and of the particulate organic carbon (POC) in particular, was exported from the shelf, across the shelf/slope break and front, into the waters of, and, to some degree, deposited in the sediments of the continental slope. This hypothesis was based on budgets of organic carbon and lead-210 that did not account for a large proportion of those species in the waters or sediments of the shelf, and on a carbon-rich band of sediments centered on the slope at ∼1,000 m water depth. The results of the first SEEP experiment, south of New England and Long Island (SEEP-1) suggested, but did not prove, that there was only a relatively small proportion of the carbon which was exported from the shelf to the slope. The objective of the second experiment -- SEEP-2 -- done under the subject grant, was to tighten the experiment in terms of the kinds of data collected, and to focus it more on the shelf and only the upper slope, where shelf-derived particles were thought to be deposited

  20. Short term variation in particulate matter in the shelf waters of the Princess Astrid Coast, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.; Bhosle, N.B.

    Particulate matter collected at a single station in the shelf waters of Princess Astrid coast (70 degrees S, 11 degrees E) Antarctica, during the austral summer (Jan.-Feb. 1986) was analysed for phytoplankton biomass (Chl @ia@@), living carbon (ATP...

  1. The effects of sub-ice-shelf melting on dense shelf water formation and export in idealized simulations of Antarctic margins

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    Marques, Gustavo; Stern, Alon; Harrison, Matthew; Sergienko, Olga; Hallberg, Robert

    2017-04-01

    Dense shelf water (DSW) is formed in coastal polynyas around Antarctica as a result of intense cooling and brine rejection. A fraction of this water reaches ice shelves cavities and is modified due to interactions with sub-ice-shelf melt water. This modified water mass contributes to the formation of Antarctic Bottom Water, and consequently, influences the large-scale ocean circulation. Here, we investigate the role of sub-ice-shelf melting in the formation and export of DSW using idealized simulations with an isopycnal ocean model (MOM6) coupled with a sea ice model (SIS2) and a thermodynamic active ice shelf. A set of experiments is conducted with variable horizontal grid resolutions (0.5, 1.0 and 2.0 km), ice shelf geometries and atmospheric forcing. In all simulations DSW is spontaneously formed in coastal polynyas due to the combined effect of the imposed atmospheric forcing and the ocean state. Our results show that sub-ice-shelf melting can significantly change the rate of dense shelf water outflows, highlighting the importance of this process to correctly represent bottom water formation.

  2. Seasonal cycle of circulation in the Antarctic Peninsula and the off-shelf transport of shelf waters into southern Drake Passage and Scotia Sea

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    Jiang, Mingshun; Charette, Matthew A.; Measures, Christopher I.; Zhu, Yiwu; Zhou, Meng

    2013-06-01

    The seasonal cycle of circulation and transport in the Antarctic Peninsula shelf region is investigated using a high-resolution (˜2 km) regional model based on the Regional Oceanic Modeling System (ROMS). The model also includes a naturally occurring tracer with a strong source over the shelf (radium isotope 228Ra, t1/2=5.8 years) to investigate the sediment Fe input and its transport. The model is spun-up for three years using climatological boundary and surface forcing and then run for the 2004-2006 period using realistic forcing. Model results suggest a persistent and coherent circulation system throughout the year consisting of several major components that converge water masses from various sources toward Elephant Island. These currents are largely in geostrophic balance, driven by surface winds, topographic steering, and large-scale forcing. Strong off-shelf transport of the Fe-rich shelf waters takes place over the northeastern shelf/slope of Elephant Island, driven by a combination of topographic steering, extension of shelf currents, and strong horizontal mixing between the ACC and shelf waters. These results are generally consistent with recent and historical observational studies. Both the shelf circulation and off-shelf transport show a significant seasonality, mainly due to the seasonal changes of surface winds and large-scale circulation. Modeled and observed distributions of 228Ra suggest that a majority of Fe-rich upper layer waters exported off-shelf around Elephant Island are carried by the shelfbreak current and the Bransfield Strait Current from the shallow sills between Gerlache Strait and Livingston Island, and northern shelf of the South Shetland Islands, where strong winter mixing supplies much of the sediment derived nutrients (including Fe) input to the surface layer.

  3. Circumpolar Deep Water transport and current structure at the Amundsen Sea shelf break

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    Assmann, Karen M.; Wåhlin, Anna K.; Heywood, Karen J.; Jenkins, Adrian; Kim, Tae Wan; Lee, Sang Hoon

    2017-04-01

    The West Antarctic Ice Sheet has been losing mass at an increasing rate over the past decades. Ocean heat transport to the ice-ocean interface has been identified as an important contributor to this mass loss and the role it plays in ice sheet stability makes it crucial to understand its drivers in order to make accurate future projections of global sea level. While processes closer to the ice-ocean interface modulate this heat transport, its ultimate source is located in the deep basin off the continental shelf as a core of relatively warm, salty water underlying a colder, fresher shallow surface layer. To reach the marine terminating glaciers and the base of floating ice shelves, this warm, salty water mass must cross the bathymetric obstacle of the shelf break. Glacial troughs that intersect the Amundsen shelf break and deepen southwards towards the ice shelf fronts have been shown to play an important role in transporting warm, salty Circumpolar Deep Water (CDW) towards the ice shelves. North of the shelf break, circulation in the Amundsen Sea occupies an intermediate regime between the eastward Antarctic Circumpolar Current that impinges on the shelf break in the Bellingshausen Sea and the westward southern limb of the Ross Gyre that follows the shelf break in the Ross Sea. Hydrographic and mooring observations and numerical model results at the mouth of the central shelf break trough leading to Pine Island and Thwaites Glaciers show a westward wind-driven shelf break current overlying an eastward undercurrent that turns onto the shelf in the trough. It is thought that the existence of the latter feature facilitates the on-shelf transport of CDW. A less clearly defined shelf break depression further west acts as the main pathway for CDW to Dotson and eastern Getz Ice shelves. Model results indicate that a similar eastward undercurrent exists here driving the on-shelf transport of CDW. Two moorings on the upper slope east of the trough entrance show a

  4. On the dense water cascading in the Southern Adriatic Sea during 2012: Setup of a Rapid Environmental Assessment

    Science.gov (United States)

    Langone, Leonardo

    2013-04-01

    In the North Adriatic, Dense Shelf Water (DSW) forms during cold and dry winters by cooling and evaporation. DSW spreads southward along the western shelf reaching the southern Adriatic basin (1200 m deep) after 1-2 months, where sinks through cascading events. In February 2012, a large Siberian High caused blocking of the Atlantic flow and a westward flow of dry and cold air masses from eastern Russia toward Europe. The North Adriatic experienced a cold spell with large decrease of surface temperature (3° -6° C) associated to severe cold and dry Bora wind. The result was the formation of extremely dense shelf water, further made possible by the very limited discharge of the Po river in the preceding autumn. As contribution to the Italian research programme RITMARE (Italian Research for the Sea), CNR-ISMAR set up a Rapid Environmental Assessment (REA) experiment to study the occurrence, amount, timing and properties of the newly formed DSW. Setting up REA strategies is crucial for several scientific and practical reasons: (i) capturing extreme events to improve our understanding of natural systems in a global-change scenario; (ii) to evaluate their impact on marine systems and the biota; (iii) to address issues related to fluctuating fish stocks as well as (iv) C export and sequestration in the deep sea. The experiment was designed with an integrated approach, including modeling simulations, mooring deployments and quick-response oceanographic cruises. Based on numerical model ensemble, the arrival time of the DSW at the Gargano Cape was forecasted likely starting after March 15, 2012, thus moorings were deployed few days before. Five moorings were deployed in sites selected on the basis of modelling predictions and geology-driven inferences defining areas where the passage of dense shelf water is most likely to occur. Moorings were equipped with down-looking ADCPs, automatic sediment traps, temperature loggers, recorders of temperature, conductivity and

  5. Carbon dioxide degassing in fresh and saline water I: Degassing performance of a cascade column

    DEFF Research Database (Denmark)

    Moran, Damian

    2010-01-01

    A study was undertaken to measure carbon dioxide degassing in a cascade column operating with both fresh (0‰) and saline water (35‰ NaCl) at 15 °C. The cascade column contained bio-block type packing material, was 1.7 m long in each dimension, and was tested both with and without countercurrent a...

  6. Amazon water lenses and the influence of the North Brazil Current on the continental shelf

    Science.gov (United States)

    Prestes, Yuri O.; Silva, Alex Costa da; Jeandel, Catherine

    2018-05-01

    The exchange processes on the Amazon continental shelf in northern Brazil are subject to complex interactions that involve forcings derived from distinct sources. The Amazon shelf is a unique and highly dynamic environment in which considerable discharge of freshwater enters the Atlantic Ocean, producing extensive Amazon Water Lenses (AWL). In addition to the presence of the AWL, the shelf is influenced by the semidiurnal oscillations of the tides and the strong North Brazil Current (NBC), a boundary current of the western Atlantic. The present study was based primarily on the influence of the freshwater input and the NBC on the shelf and the Amazon Shelf Break (ASB) off the mouth of the Pará River. For this purpose, hydrographic and hydrodynamic data were obtained by moorings of the AMANDES Project (April-July 2008), located on the Amazon shelf and the ASB. Spectral analysis and the continuous wavelet transform were applied to define tidal (high frequency/short period) and subtidal (low frequency/long period) signals. The results indicated that on both the shelf and the break, the semidiurnal tides are responsible for the residual landward transport and are predominantly across-shelf. Low-frequency motions in the synoptic bands and the AWL are related to spatial changes in the velocity field, mainly on the ASB in the along-shelf direction. The flow of the NBC can be interpreted as an along-shelf low-frequency oscillation capable of altering the spatial configuration of the velocity field, although its influence is perceived only in the absence of the AWL.

  7. Seasonal and inter-annual temperature variability in the bottom waters over the Black Sea shelf

    Science.gov (United States)

    Shapiro, G. I.; Wobus, F.; Aleynik, D. L.

    2011-02-01

    Long-term changes in the state of the Bottom Shelf Water (BSW) on the Western shelf of the Black Sea are assessed using analysis of intra- and inter-annual variations of temperature as well as their relations to physical parameters of both shelf and deep-sea waters. First, large data sets of in-situ observations over the 20th century are compiled into high-resolution monthly climatology at different depth levels. Then, the temperature anomalies from the climatic mean are calculated and aggregated into spatial compartments and seasonal bins to reveal temporal evolution of the BSW. For the purpose of this study the BSW is defined as such shelf water body between the seabed and the upper mixed layer (bounded by the σθ = 14.2 isopycnal) which has limited ability to mix vertically with oxygen-rich surface waters during the warm season (May-November) due to the formation of a seasonal pycnocline. The effects of atmospheric processes at the surface on the BSW are hence suppressed as well as the action of the "biological pump". The vertical extent of the near- bottom waters is determined based on energy considerations and the structure of the seasonal pycnocline, whilst the horizontal extent is controlled by the shelf break, where strong along-slope currents hinder exchanges with the deep sea. The BSW is shown to occupy nearly half of the area of the shelf during the summer stratification period. The potential of the BSW to ventilate horizontally during the warm season with the deep-sea waters is assessed using isopycnic analysis of temperature variations. A long-term time series of temperature anomalies in the BSW is constructed from observations during the May-November period for the 2nd half of the 20th century. The results reveal a warm phase in the 1960s/70s, followed by cooling of the BSW during 1980-2001. The transition between the warm and cold periods coincides with a regime shift in the Black Sea ecosystem. While it was confirmed that the memory of winter

  8. Cascades for natural water enrichment in deuterium and oxygen-18 using membrane permeation

    International Nuclear Information System (INIS)

    Chmielewski, A.G.; Matuszak, A.; Zakrzewska-Trznadel, G.; Van Hook, A.

    1991-01-01

    The enrichment of water in heavy isotopes by permeation through a hydrophobic membrane is described. Simple counter - current cascades are of no practical interest because of their high energy demand. A better solution is to employ a double counter - current cascade re-utilizing part of the heat of condensation. Currently employed methods of natural water enrichment in heavy isotopes are compared to the proposed membrane process. (author). 18 refs, 14 tabs, 21 figs

  9. Transport and transfer rates in the waters of the continental shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.

    1980-09-01

    The goal of govern project is to understand and quantify the processes that the transport and dispersal of energy-related pollutants introduced to the waters of the continental shelf and slope. The report is divided into sections dealing with processes associated with suspended solids; processes associated with sediments sinks for radionuclides and other pollutants; and spreading of water characteristics and species in solution

  10. The European water framework directive: A challenge for nearshore, coastal and continental shelf research

    Science.gov (United States)

    Borja, Ángel

    2005-09-01

    The European Water Framework Directive (WFD) establishes a framework for the protection of groundwater, inland surface waters, estuarine waters, and coastal waters. The WFD constitutes a new view of the water resources management in Europe because, for the first time, water management is: (i) based mainly upon biological and ecological elements, with ecosystems being at the centre of the management decisions; (ii) applied to European water bodies, as a whole; and (iii) based upon the whole river basin, including also the adjacent coastal area. Although the marine water bodies affected by the WFD relate to only 19.8% of the whole of the European continental shelf, its application constitutes a challenge and an opportunity in nearshore, coastal and continental shelf research. This contribution highlights some of the main tasks and the research to be undertaken in the coming years, proposing investigations into: typologies; physico-chemical processes; indicator species; reference conditions; integration of the quality assessment; methodologies in determining ecological status, etc.

  11. 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.

  12. Distribution of Upper Circumpolar Deep Water on the warming continental shelf of the West Antarctic Peninsula

    Science.gov (United States)

    Couto, Nicole; Martinson, Douglas G.; Kohut, Josh; Schofield, Oscar

    2017-07-01

    We use autonomous underwater vehicles to characterize the spatial distribution of Upper Circumpolar Deep Water (UCDW) on the continental shelf of the West Antarctic Peninsula (WAP) and present the first near-synoptic measurements of mesoscale features (eddies) containing UCDW on the WAP. Thirty-three subsurface eddies with widths on the order of 10 km were detected during four glider deployments. Each eddy contributed an average of 5.8 × 1016 J to the subpycnocline waters, where a cross-shelf heat flux of 1.37 × 1019 J yr-1 is required to balance the diffusive loss of heat to overlying winter water and to the near-coastal waters. Approximately two-thirds of the heat coming onto the shelf diffuses across the pycnocline and one-third diffuses to the coastal waters; long-term warming of the subpycnocline waters is a small residual of this balance. Sixty percent of the profiles that contained UCDW were part of a coherent eddy. Between 20% and 53% of the lateral onshore heat flux to the WAP can be attributed to eddies entering Marguerite Trough, a feature in the southern part of the shelf which is known to be an important conduit for UCDW. A northern trough is identified as additional important location for eddy intrusion.

  13. Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

  14. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Directory of Open Access Journals (Sweden)

    Luis Carlos Pinto de Macedo-Soares

    Full Text Available Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  15. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  16. 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.

  17. Advanced electrolytic cascade process for tritium recovery from irradiated heavy water moderator (Preprint No. PD-15)

    International Nuclear Information System (INIS)

    Ragunathan, P.; Mitra, S.K.; Jain, D.K.; Nayar, M.G.; Ramani, M.P.S.

    1989-04-01

    The paper briefly describes a design study of an electrolytic cascade process plant for enrichment and recovery of tritium from irradiated heavy water moderators from Rajasthan Atomic Power Station Reactors. In direct multistage electrolysis process, tritiated heavy water from the reactor units is fed to the electrolytic cell modules arranged in the form of a cascade where it is enriched and decomposed into O 2 gas stream and D 2 /DT gas stream. The direct electrolysis of tritiated heavy water allows tritium to be concentrated in the aqueous phase. Several stages are used to achieve the necessary enrichment. The cascade plant incorporates the advanced electrolyser technology developed in Bhabha Atomic Research Centre (Bombay) using porous nickel electrodes, capable o f high current density operation at reduced energy consumption for electrolysis. (author). 3 tabs

  18. Transport and transfer rates in the waters of the continental shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.; Broecker, W.S.; Feely, H.W.; Gerard, R.D.

    1976-04-01

    The report is to the Energy Research and Development Administration on accomplishments of the Lamont-Doherty Geological Observatory geochemistry and physical oceanography groups during the 1975-1976 funding period on grant E(11-1)2185. Goals are to obtain detailed, quantitative knowledge of the rates of mixing within coastal waters of the New York Bight and across the continental slope and the exchange of water masses and species transported within them between shelf and Atlantic Ocean waters. The research is aimed at understanding the chemical, physical, and biological processes which control the origin, dispersal, and fate of particulate matter and trace metals, and to ultimately model the impact of energy related pollutants on the continental shelf

  19. Atlantic water variability on the SE Greenland continental shelf and its relationship to SST

    Science.gov (United States)

    Sutherland, D. A.; Straneo, F.; Rosing-Asvid, A.; Stenson, G.; Davidson, F. J.; Hammill, M.

    2012-12-01

    Interaction of warm, Atlantic-origin water (AW) and colder, polar origin water (PW) advecting southward in the East Greenland Current (EGC) influences the heat content of water entering Greenland's outlet glacial fjords. Here we use depth and temperature data derived from deep-diving seals to map out water mass variability across the continental shelf and to augment existing bathymetric products. We find two dominant modes in the vertical temperature structure: a cold mode, with the typical AW/PW layering observed in the EGC, and a warm mode, where AW is present throughout the water column. The prevalence of these modes varies seasonally and spatially across the continental shelf, implying distinct AW pathways. In addition, we find that satellite sea surface temperatures (SST) correlate significantly with temperatures in the upper 50 m (R=0.54), but this correlation decreases with depth (R=0.22 at 200 m), and becomes insignificant below 250 m. Thus, care must be taken in using SST as a proxy for heat content, as AW mainly resides in these deeper layers. Regional map showing the location of all seal tracks originating from Canada and Greenland (stars). Tracks passing inside (red) or outside (blue) the SE Greenland region (black) were subdivided into continental shelf regions (green boxes) near Sermilik Fjord (SF), Cape Farewell (CF) and Kangerdlugssuaq Fjord (KG). GEBCO bathymetry is contoured at 200, 1000, 2000, and 3000 m.

  20. Food supply mechanisms for cold-water corals along a continental shelf edge

    Science.gov (United States)

    Thiem, Øyvind; Ravagnan, Elisa; Fosså, Jan Helge; Berntsen, Jarle

    2006-05-01

    In recent years it has been documented that deep-water coral reefs of the species Lophelia pertusa are a major benthic habitat in Norwegian waters. However, basic information about the biology and ecology of this species is still unknown. Lophelia live and thrive under special environmental conditions of which factors such as temperature, water depth, water movement and food supply are important. The present work explores the hypothesis that Lophelia forms reefs in places where the encounter rate of food particles is sufficiently high and stable over long periods of time for continuous growth. This is done by relating the distribution of reefs with the results of numerical ocean modelling. Numerical simulations have been performed with an idealized bottom topography similar to what is found outside parts of the Norwegian coast. In the simulations the model is first forced with an along slope jet and then with an idealized atmospheric low pressure. The model results show that the encounter rates between the particles and the water layer near the seabed are particularly high close to the shelf break. This may indicate that many Lophelia reefs are located along the shelf edges because the supply of food is particularly good in these areas. A sensitivity study of the particle supply in the area close to the seabed for increasing latitude has also been done. This shows that the Ekman transport in the benthic layer tends to create a steady supply of food for benthic organisms near the shelf edge away from the equator.

  1. Fluorescent dissolved organic matter in the continental shelf waters ...

    Indian Academy of Sciences (India)

    Fluorescent dissolved organic matter (FDOM) of southwestern Bay of Bengal surface water during southwest monsoon consisted five fluorophores, three humic-like and two protein-like. The humification index (HIX) and humic fluorophores, viz., visible (C), marine (M) and UV (A) humic-likes indicated, better than ...

  2. PARAMETRIC STUDY OF ENERGY, EXERGY AND THERMOECONOMIC ANALYSES ON VAPOR-COMPRESSION SYSTEM CASCADED WITH LIBR/WATER AND NH3/WATER ABSORBTION CASCADE REFRIGERATION CYCLE

    Directory of Open Access Journals (Sweden)

    ahmet selim dalkilic

    2017-03-01

    Full Text Available Energy savings on cooling systems can be performed by using novel refrigeration cycles. For this aim, vapour compression-vapour absorption cascade refrigeration systems can be considered as substitute to single-stage vapour compression refrigeration systems. Renewable energy sources of geothermal and solar heat, waste heat of processes have been used by these cycles to provide cooling and they also require less electrical energy than vapour compression cycles having alternative refrigerants. In this study, a vapour compression (VC and vapour absorption (VA cascade systems are analysed with the second law analysis for varied cooling capacities. While lithium bromide-water and NH3/H2O are the working fluids in VA part, various refrigerants are used in VC section. The refrigerants of R134a and R600a, R410A and R407C are tested as drop in alternatives for R12 and R22, respectively. The effects of alteration in cooling capacity, superheating and sub cooling in VC part, temperature in the generator and absorber, and degree of overlap in cascade condenser in VA part on the coefficient of system performance are studied. Validation of the results have been performed by the values given in the literature. Improvement in COP of VC, VA and cascade system are obtained separately. According to the analyses, cascade systems’ COP values increase with increasing the temperatures of generator and evaporator and they also increase with decreasing the condenser and absorber temperatures. Moreover, the generator has the highest exergy destruction rates, second and third one were the condenser and absorber, respectively. Electricity consumption and payback period are also determined considering the various parameters of the study.

  3. Radium variability produced by shelf-water transport and mixing in the western Gulf of Mexico

    International Nuclear Information System (INIS)

    Reid, D.F.

    1984-01-01

    226 Ra and 228 Ra exhibit significant temporal and spatial variability in the near-surface western Gulf of Mexico. Concentrations of both isotopes during March 1976 were approx. 22 to 26% greater than those observed during February 1973. It is shown that analytical differences cannot account for this increase. Consideration of radium levels in the western Caribbean Sea indicates that there must be an internal source of radium that has a significant but temporally variable influence on near-surface radium concentrations in the western Gulf. Comparisons of radium, salinity, and temperature data from 1973 and 1976 provide evidence that advective transport and mixing of radium-rich shelf water with the interior water column of the western basin is responsible for the variability. By plotting 228 Ra vs 226 Ra from this region, estimates of the apparent shelf-water component in the upper water column can be made. The results indicate 36% over the northern slope, 10 to 18% in the central western Gulf, and 3 to 7% over Campeche Bank. In addition to explaining observed short-term variations of radium in this region, this information should be useful for environmental impact assessments concerned with industrial discharges on the northern shelf. (author)

  4. Installation package for a sunspot cascade solar water heating system

    Science.gov (United States)

    1980-01-01

    Solar water heating systems installed at Tempe, Arizona and San Diego, California are described. The systems consist of the following: collector, collector-tank water loop, solar tank, conventional tank, and controls. General guidelines which may be utilized in development of detailed installation plans and specifications are provided along with instruction on operation, maintenance, and installation of solar hot water systems.

  5. Surface-water radon-222 distribution along the west-central Florida shelf

    Science.gov (United States)

    Smith, C.G.; Robbins, L.L.

    2012-01-01

    In February 2009 and August 2009, the spatial distribution of radon-222 in surface water was mapped along the west-central Florida shelf as collaboration between the Response of Florida Shelf Ecosystems to Climate Change project and a U.S. Geological Survey Mendenhall Research Fellowship project. This report summarizes the surface distribution of radon-222 from two cruises and evaluates potential physical controls on radon-222 fluxes. Radon-222 is an inert gas produced overwhelmingly in sediment and has a short half-life of 3.8 days; activities in surface water ranged between 30 and 170 becquerels per cubic meter. Overall, radon-222 activities were enriched in nearshore surface waters relative to offshore waters. Dilution in offshore waters is expected to be the cause of the low offshore activities. While thermal stratification of the water column during the August survey may explain higher radon-222 activities relative to the February survey, radon-222 activity and integrated surface-water inventories decreased exponentially from the shoreline during both cruises. By estimating radon-222 evasion by wind from nearby buoy data and accounting for internal production from dissolved radium-226, its radiogenic long-lived parent, a simple one-dimensional model was implemented to determine the role that offshore mixing, benthic influx, and decay have on the distribution of excess radon-222 inventories along the west Florida shelf. For multiple statistically based boundary condition scenarios (first quartile, median, third quartile, and maximum radon-222 inshore of 5 kilometers), the cross-shelf mixing rates and average nearshore submarine groundwater discharge (SGD) rates varied from 100.38 to 10-3.4 square kilometers per day and 0.00 to 1.70 centimeters per day, respectively. This dataset and modeling provide the first attempt to assess cross-shelf mixing and SGD on such a large spatial scale. Such estimates help scale up SGD rates that are often made at 1- to 10-meter

  6. Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA

    Science.gov (United States)

    Noble, Marlene A.; Burt Jones,; Peter Hamilton,; Xu, Jingping; George Robertson,; Rosenfeld, Leslie; John Largier,

    2009-01-01

    In the summer of 2001, a coastal ocean measurement program in the southeastern portion of San Pedro Bay, CA, was designed and carried out. One aim of the program was to determine the strength and effectiveness of local cross-shelf transport processes. A particular objective was to assess the ability of semidiurnal internal tidal currents to move suspended material a net distance across the shelf. Hence, a dense array of moorings was deployed across the shelf to monitor the transport patterns associated with fluctuations in currents, temperature and salinity. An associated hydrographic program periodically monitored synoptic changes in the spatial patterns of temperature, salinity, nutrients and bacteria. This set of measurements show that a series of energetic internal tides can, but do not always, transport subthermocline water, dissolved and suspended material from the middle of the shelf into the surfzone. Effective cross-shelf transport occurs only when (1) internal tides at the shelf break are strong and (2) subtidal currents flow strongly downcoast. The subtidal downcoast flow causes isotherms to tilt upward toward the coast, which allows energetic, nonlinear internal tidal currents to carry subthermocline waters into the surfzone. During these events, which may last for several days, the transported water remains in the surfzone until the internal tidal current pulses and/or the downcoast subtidal currents disappear. This nonlinear internal tide cross-shelf transport process was capable of carrying water and the associated suspended or dissolved material from the mid-shelf into the surfzone, but there were no observation of transport from the shelf break into the surfzone. Dissolved nutrients and suspended particulates (such as phytoplankton) transported from the mid-shelf into the nearshore region by nonlinear internal tides may contribute to nearshore algal blooms, including harmful algal blooms that occur off local beaches.

  7. Distribution of nutrients in the shelf waters of the Arabian sea along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, C.V.G.; Sankaranarayanan, V.N.

    The paper presents a descriptive account of the distribution of phosphates, silicates and nitrates in the shelf waters of Arabian Sea along the West Coast of India including a brief mention about the hydrographical features and their relationship...

  8. Carbon and oxygen dynamics on the Louisiana continental shelf: role of water column primary production and respiration

    Science.gov (United States)

    We conducted a multi-year study of the Louisiana continental shelf (LCS) to better understand the linkages between water column net metabolism and the formation of hypoxia (dissolved oxygen respiration (R) and primary p...

  9. Radon-222 and radium-226 in southeastern Bering Sea shelf waters and sediment

    International Nuclear Information System (INIS)

    Glover, D.M.; Reeburgh, W.S.

    1987-01-01

    Radon-222 and 226 Ra activities were measured in the waters and sediment of the southeastern Bering Sea shelf to evaluate the use of radon as a tracer of gas exchange, water column mixing and sediment-water exchange. Cross-shelf distributions of 222 Rn and 226 Ra are presented. Gas transfer coefficients were estimated using near-surface 222 Rn deficiency measurements. A statistically significant linear relationship between averaged wind speed and transfer coefficient was found. Vertical eddy diffusivities were evaluated by applying a one-dimensional model to near-bottom excess 222 Rn distributions; these diffusivities were compared to independently determined values. The one-dimensional model applied to the near-bottom 222 Rn data was found to be inadequate and a two-dimensional model was applied to improve the fit between model and data. Exchange across the sediment-water interface was computed from the deficiency of 222 Rn measured in sediment cores, standing crop estimates of excess 222 Rn in the water column and 222 Rn production rates of sediment surface grab samples. Biological irrigation of the sediments appeared to be the primary exchange mechanism between the sediment and water columns. Distributions in the water column showed finestructure reported previously and suggested biological removal of 226 Ra. (author)

  10. Serviceability Assessment for Cascading Failures in Water Distribution Network under Seismic Scenario

    Directory of Open Access Journals (Sweden)

    Qing Shuang

    2016-01-01

    Full Text Available The stability of water service is a hot point in industrial production, public safety, and academic research. The paper establishes a service evaluation model for the water distribution network (WDN. The serviceability is measured in three aspects: (1 the functionality of structural components under disaster environment; (2 the recognition of cascading failure process; and (3 the calculation of system reliability. The node and edge failures in WDN are interrelated under seismic excitations. The cascading failure process is provided with the balance of water supply and demand. The matrix-based system reliability (MSR method is used to represent the system events and calculate the nonfailure probability. An example is used to illustrate the proposed method. The cascading failure processes with different node failures are simulated. The serviceability is analyzed. The critical node can be identified. The result shows that the aged network has a greater influence on the system service under seismic scenario. The maintenance could improve the antidisaster ability of WDN. Priority should be given to controlling the time between the initial failure and the first secondary failure, for taking postdisaster emergency measures within this time period can largely cut down the spread of cascade effect in the whole WDN.

  11. Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay)

    KAUST Repository

    Álvarez, E

    2015-12-09

    © Inter-Research 2016. Shelf waters of the Cantabrian Sea (southern Bay of Biscay) are productive ecosystems with a marked seasonality. We present the results from 1 yr of monthly monitoring of the phytoplankton community together with an intensive sampling carried out in 2 contrasting scenarios during the summer and autumn in a mid-shelf area. Stratification was apparent on the shelf in summer, while the water column was comparatively well mixed in autumn. The size structure of the photoautotrophic community, from pico-to micro-phytoplankton, was tightly coupled with the meteo-climatic and hydrographical conditions. Over the short term, variations in the size structure and chlorophyll content of phytoplankton cells were related to changes in the physico-chemical environment, through changes in the availability of nutrients and light. Uncoupling between the dynamics of carbon biomass and chlorophyll resulted in chlorophyll to carbon ratios dependent on body size. The slope of the size dependence of chlorophyll content increased with increasing irradiance, reflecting different photoacclimation plasticity from pico-to micro-phytoplankton. The results have important implications for the productivity and the fate of biogenic carbon in this region, since the size dependence of photosynthetic rates is directly related to the size scaling of chlorophyll content.

  12. Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay)

    KAUST Repository

    Á lvarez, E; Moran, Xose Anxelu G.; Ló pez-Urrutia, Á ; Nogueira, E

    2015-01-01

    © Inter-Research 2016. Shelf waters of the Cantabrian Sea (southern Bay of Biscay) are productive ecosystems with a marked seasonality. We present the results from 1 yr of monthly monitoring of the phytoplankton community together with an intensive sampling carried out in 2 contrasting scenarios during the summer and autumn in a mid-shelf area. Stratification was apparent on the shelf in summer, while the water column was comparatively well mixed in autumn. The size structure of the photoautotrophic community, from pico-to micro-phytoplankton, was tightly coupled with the meteo-climatic and hydrographical conditions. Over the short term, variations in the size structure and chlorophyll content of phytoplankton cells were related to changes in the physico-chemical environment, through changes in the availability of nutrients and light. Uncoupling between the dynamics of carbon biomass and chlorophyll resulted in chlorophyll to carbon ratios dependent on body size. The slope of the size dependence of chlorophyll content increased with increasing irradiance, reflecting different photoacclimation plasticity from pico-to micro-phytoplankton. The results have important implications for the productivity and the fate of biogenic carbon in this region, since the size dependence of photosynthetic rates is directly related to the size scaling of chlorophyll content.

  13. Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

    Science.gov (United States)

    Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

    2018-01-01

    In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

  14. Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015

    Science.gov (United States)

    Li, Denghui; Zhou, Meng; Zhang, Zhaoru; Zhong, Yisen; Zhu, Yiwu; Yang, Chenghao; Xu, Mingquan; Xu, Dongfeng; Hu, Ziyuan

    2018-06-01

    The northern slope region of the South China Sea (SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by cross-shelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55-m water masses on the SCS northern slope and thereby elucidate the cross-slope transport of shelf water (SHW) and the intrusions of Kuroshio water (KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water (SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong cross-slope current with speeds greater than 50 cm s-1 to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area.

  15. Transport and transfer rates in the waters of the Continental Shelf. Annual report

    International Nuclear Information System (INIS)

    Biscaye, P.E.

    1978-07-01

    The present contract year has been one of transition from an emphasis on field work and sample gathering to the predominance of sample and data analysis and the formulation of testable hypotheses concerning specific processes in the New York Bight. We have begun to understand the seasonal transition in the role of phytoplankton vs. grazing zooplankton in forming the particles on which some reactive pollutants are removed. Using natural radioactive tracers we have estimated the removal rates of reactive metals from the surface waters and these range over an order of magnitude from most rapid nearshore to least rapid over the upper continental slope. Once removed nearshore, however, these tracers, and the pollutants for which they proxy, do not remain permanently in the sediments but appear to be remobilized (probably by oxidation) during the winter and are reintroduced into the water column. Work on transport and mixing processes of pollutants which are or behave like those in solution has continued along several fronts. Hydrographic data on the structure of the water column continues to give a description of the system that is crucial to understanding geochemical and biological processes which affect pollutants. Hydrographic characterization of water masses from the data sets of cruises has resulted in hypotheses concerning the renewal of shelf water by direct exchange between shelf and upper slope water

  16. Oil, gas potential in shallow water: Peru`s continental shelf basins

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Rivero, F.; Keeling, J.A.; Hay-Roe, H. [BPZ and Associates Inc., Houston, TX (United States)

    1998-11-16

    This third article of a series highlights the three sedimentary basins that underlie the 16 million acres of continental shelf adjacent to a 650-mile stretch of Peruvian coastline. This area lies roughly between the ports of Chiclayo and Pisco. These basins offer a variety of reservoirs, traps, and source-rock potential in water depths of less than 1,000 ft. They are characterized by a thick sequence of Neogene strata, underlain by Paleogene, Mesozoic, and Upper Paleozoic sediments down to as much as 7 sec two-way time on modern seismic records. In some places the sedimentary section may reach an aggregate thickness in excess of 50,000 ft. From north to south these contiguous shelf basins are the Sechura-Salaverry, Huacho, and Pisco basins. All three basins are described.

  17. Export of Ice-Cavity Water from Pine Island Ice Shelf, West Antarctica

    Science.gov (United States)

    Thurnherr, Andreas; Jacobs, Stanley; Dutrieux, Pierre

    2013-04-01

    Stability of the West Antarctic Ice Sheet is sensitive to changes in melting at the bottom of floating ice shelves that form the seaward extensions of Antarctic glaciers flowing into the ocean. Not least because observations in the cavities beneath ice shelves are difficult, heat fluxes and melt rates have been inferred from oceanographic measurements obtained near the ice edge (calving fronts). Here, we report on a set of hydrographic and velocity data collected in early 2009 near the calving front of the Amundsen Sea's fast-moving and (until recently) accelerating Pine Island Glacier and its associated ice shelf. CTD profiles collected along the southern half of the meridionally-trending ice front show clear evidence for export of ice-cavity water. That water was carried in the upper ocean along the ice front by a southward current that is possibly related to a striking clockwise gyre that dominated the (summertime) upper-ocean circulation in Pine Island Bay. Signatures of ice-cavity water appear unrelated to current direction along most of the ice front, suggesting that cross-frontal exchange is dominated by temporal variability. However, repeated hydrographic and velocity measurements in a small "ice cove" at the southern end of the calving front show a persistent strong (mean velocity peaking near 0.5 ms-1) outflow of ice-cavity water in the upper 500 m. While surface features (boils) suggested upwelling from deep below the ice shelf, vertical velocity measurements reveal 1) that the mean upwelling within the confines of the cove was too weak to feed the observed outflow, and 2) that large high-frequency internal waves dominated the vertical motion of water inside the cove. These observations indicate that water exchange between the Pine Island Ice Shelf cavity and the Amundsen sea is strongly asymmetric with weak broad inflow at depth and concentrated surface-intensified outflow of melt-laden deep water at the southern edge of the calving front. The lack of

  18. Modeling elephant-mediated cascading effects of water point closure

    NARCIS (Netherlands)

    Hilbers, J.P.; Langevelde, van F.; Prins, H.H.T.; Grant, C.C.; Peel, M.; Coughenour, M.B.; Knegt, de H.J.; Slotow, R.; Smit, I.; Kiker, G.A.; Boer, de W.F.

    2015-01-01

    Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are however alternative ways to control wildlife densities, such as opening or closing water points. The

  19. 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.

  20. Multi-Tracer Approach for Shelf Water Mixing Studies in Brazilian Regions under Different Climates

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, L. D.; Marins, R. V.; Dias, F. J.S. [Instituto de Ciencias do Mar, Universidate Federal do Ceara, Fortaleza, CE (Brazil); Godoy, M. L.D.P. [Instituto de Radioprotecao e Dosimetria, Comissao Nacional de Energia Nuclear, Rio de Janeiro, RJ (Brazil); Godoy, J. M.; Souza, T. A. [Departamento de Quimica, Pontificia Universidade Catolica, Rio de Janeiro, RJ (Brazil); Rezende, C. E. [Centro de Biociencias e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ (Brazil)

    2013-07-15

    Fresh water and sediment supply at estuary and plume regions has dramatically changed due to land use changes, mostly damming, in river basins. The resulting impact, however, may vary significantly depending on climate and hydrology. The seasonal differences in shelf, plume, estuarine and river waters of two watersheds located under contrasting climates in the Brazilian coast are reported using a multi-tracer approach (salinity, barium, silica, uranium, deuterium and {sup 18}O) to characterize the mixing processes. At the Paraiba do Sul River, SE Brazil, in a wet tropical coast, all results showed similarity between dry and wet seasons; at the Jaguaribe river under semi arid climate in NE Brazil, the results showed a moving freshwater plume depending on season, with freshwater at the estuary in the rainy season and shelf water intrusion upstream in the estuary in the dry season. Most tracers used were able to consistently characterize water masses even in the wide range of latitudes studied, confirming their importance as a tool for modelling mixing processes at the continent-ocean boundary. Barium, however, still needs better studies on its seashore chemistry, since in the semi arid site, Ba distribution could not be directly related to conservative mixing behaviour, at least during the rainy season. (author)

  1. Modeling elephant-mediated cascading effects of water point closure.

    Science.gov (United States)

    Hilbers, Jelle P; Van Langevelde, Frank; Prins, Herbert H T; Grant, C C; Peel, Mike J S; Coughenour, Michael B; De Knegt, Henrik J; Slotow, Rob; Smit, Izak P J; Kiker, Greg A; De Boer, Willem F

    2015-03-01

    Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are, however, alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested in order to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in availability of artificial WPs; levels of natural water; and elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of meso-mixed feeders, meso-browsers, and some meso-grazers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Under dry conditions, the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years, and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically

  2. Trophic Ecology and Movement Patters of Tiger Sharks (Galeocerdo Cuvier) off the Western North Atlantic Coastal and Continental Shelf Waters

    Science.gov (United States)

    Sancho, G.; Edman, R.; Frazier, B.; Bubley, W.

    2016-02-01

    Understanding the trophic dynamics and habitat utilization of apex predators is central to inferring their influence on different marine landscapes and to help design effective management plans for these animals. Tiger sharks (Galeocerdo cuvier) are abundant in shelf and offshore Gulf Stream waters of the western North Atlantic Ocean, and based on movements from individuals captured in Florida and Bahamas, seem to avoid coastal and shelf waters off South Carolina and Georgia. This contradicts reports of tiger sharks regularly being caught nearshore by anglers in these states, indicating that separate sub-populations may exist in the western North Atlantic. In the present study we captured Tiger Sharks in coastal waters off South Carolina in 2014 and 2015 in order to describe their movement patterns through acoustic and satellite tagging, and trophic dynamics through stable isotope analyses. Movement data show that these tiger sharks repeatedly visit particular inshore areas and mainly travel over the continental shelf, but rarely venture offshore beyond the continental shelf edge. Ongoing C and N stable isotope analyses of muscle, blood and skin tissues from adult and juvenile tiger sharks, as well as from potential prey species and primary producers, will help determine if their diets are based on inshore, shelf or offshore based food webs. Tiger sharks exploiting nearshore environments and shelf waters have much higher probabilities of interacting with humans than individuals occupying far offshore Gulf Stream habitats.

  3. Molecular Gut Content Profiling to Investigate the In Situ Grazing and Selectivity of Dolioletta gegenbauri in Summer Continental Shelf Intrusion Waters of the South Atlantic Bight, USA

    Science.gov (United States)

    Walters, T. L.; Frazier, L.; Gibson, D. M.; Paffenhofer, G. A.; Frischer, M. E.

    2016-02-01

    Gelatinous metazooplankton play a crucial role in marine planktonic food webs and it has been suggested that they may become increasingly important in the Future Ocean. However, largely due to methodological challenges and reliance on laboratory cultivation approaches, the in situ diet of zooplankton with complex life histories and diverse prey choices remains poorly investigated. This is particularly true for the gelatinous zooplankton including the pelagic tunicate, Dolioletta gegenbauri that form large blooms in productive subtropical continental shelf environments. To investigate the diet of D. gegenbauri we developed a molecular gut profiling approach based on the use of a Peptide Nucleic Acid (PNA) PCR blocker. Using a doliolid-specific PNA blocker, it was possible to enrich the amplification of prey and parasite DNA from whole animal DNA extracts of doliolids. Gut contents from the water column, wild and captive-fed doliolids were profiled after PNA-PCR by denaturing HPLC (dHPLC), clone library and next generation sequencing (NGS) approaches. Studies were conducted during 5 summer cruises in the mid-shelf of the South Atlantic Bight. Comparison of gut profiles to available prey in the water column revealed evidence of prey selection towards larger prey species, including diatoms, dinoflagelletes and also metazoan prey that were likely captured as larvae and eggs. Wild-caught doliolids contained significantly more metazoan sequences than did the captive-fed doliolids. Ingestion of metazoan prey suggests that metazoans may contribute both the nutrition of doliolids and the potential role of doliolids as trophic cascade agents in continental shelf pelagic food webs.

  4. Observed vulnerability of Filchner-Ronne Ice Shelf to wind-driven inflow of warm deep water

    Science.gov (United States)

    Darelius, E.; Fer, I.; Nicholls, K. W.

    2016-01-01

    The average rate of melting at the base of the large Filchner-Ronne Ice Shelf in the southern Weddell Sea is currently low, but projected to increase dramatically within the next century. In a model study, melt rates increase as changing ice conditions cause a redirection of a coastal current, bringing warm water of open ocean origin through the Filchner Depression and into the Filchner Ice Shelf cavity. Here we present observations from near Filchner Ice Shelf and from the Filchner Depression, which show that pulses of warm water already arrive as far south as the ice front. This southward heat transport follows the eastern flank of the Filchner Depression and is found to be directly linked to the strength of a wind-driven coastal current. Our observations emphasize the potential sensitivity of Filchner-Ronne Ice Shelf melt rates to changes in wind forcing. PMID:27481659

  5. Cascade air stripping: Techno-economic evaluation of a new ground water treatment process

    International Nuclear Information System (INIS)

    Nirmalakhandan, N.; Peace, G.L.; Shanbhag, A.R.; Speece, R.E.

    1992-01-01

    A simple modification of the conventional air-stripping process introduced as cascade air stripping is proposed for efficient and economical removal of semivolatile and low volatility contaminants from ground water. The technical feasibility and economic viability of this process are evaluated using field test results and cost model simulations. The field tests enabled the process model to be verified at various water flow rates ranging from 150 gpm to 400 gpm. The field study also demonstrated the feasibility of the proposed system at a near full-scale level. Cost models were used to compare the proposed process to conventional air stripping and granular-activated carbon adsorption in removing a range of contaminants. This analysis showed that the treatment cost (cents/1,000 gal) of cascade air stripping is about 15% lower than conventional air stripping and about 40% lower than granular-activated carbon adsorption

  6. Water, Ice, and Meteorological Measurements at South Cascade Glacier, Washington, Balance Years 2004 and 2005

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2007-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance years 2004 and 2005. The North Cascade Range in the vicinity of South Cascade Glacier accumulated smaller than normal winter snowpacks during water years 2004 and 2005. Correspondingly, the balance years 2004 and 2005 maximum winter snow balances of South Cascade Glacier, 2.08 and 1.97 meters water equivalent, respectively, were smaller than the average of such balances since 1959. The 2004 glacier summer balance (-3.73 meters water equivalent) was the eleventh most negative during 1959 to 2005 and the 2005 glacier summer balance (-4.42 meters water equivalent) was the third most negative. The relatively small winter snow balances and unusually negative summer balances of 2004 and 2005 led to an overall loss of glacier mass. The 2004 and 2005 glacier net balances, -1.65 and -2.45 meters water equivalent, respectively, were the seventh and second most negative during 1953 to 2005. For both balance years, the accumulation area ratio was less than 0.05 and the equilibrium line altitude was higher than the glacier. The unusually negative 2004 and 2005 glacier net balances, combined with a negative balance previously reported for 2003, resulted in a cumulative 3-year net balance of -6.20 meters water equivalent. No equal or greater 3-year mass loss has occurred previously during the more than 4 decades of U.S. Geological Survey mass-balance measurements at South Cascade Glacier. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The terminus retreated at a rate of about 17 meters per year during balance year 2004 and 15 meters per year during balance year 2005. Glacier area near the end of balance years 2004 and 2005 was 1.82 and 1.75 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was

  7. Arctic Ocean outflow and glacier-ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland)

    DEFF Research Database (Denmark)

    Dmitrenko, Igor A.; Kirillov, Sergey A.; Rudels, Bert

    2017-01-01

    The first-ever conductivity-temperature-depth (CTD) observations on the Wandel Sea shelf in northeastern Greenland were collected in April-May 2015. They were complemented by CTDs taken along the continental slope during the Norwegian FRAM 2014-2015 drift. The CTD profiles are used to reveal...... the origin of water masses and interactions with ambient water from the continental slope and the tidewater glacier outlet. The subsurface water is associated with the Pacific water outflow from the Arctic Ocean. The underlying halocline separates the Pacific water from a deeper layer of polar water that has...... interacted with the warm Atlantic water outflow through the Fram Strait, recorded below 140 m. Over the outer shelf, the halocline shows numerous cold density-compensated intrusions indicating lateral interaction with an ambient polar water mass across the continental slope. At the front of the tidewater...

  8. Sup(210)Pb and 210Po distributions and disequilibrium in the coastal and shelf waters of the southern North Sea

    International Nuclear Information System (INIS)

    Zhizheng, Zuo; Eisma, Doeke

    1993-01-01

    Concentration profiles of 210 Pb and 210 Po were measured at 10 stations in the coastal and shelf areas of the southern North Sea. Scavenging processes in this study area are revealed by 210 Po/ 210 Pb disequilibrium and their distributions in the water column. Results for 210 Po show strong excess, relative to 210 Pb, in both dissolved and particulate forms, indicating an additional flux of 210 Po from the coastal and shelf sediment. A significant maximum of the dissolved 210 Po and 210 Pb over the fine grained depositional area (Oyster Ground) was observed to correspond with resuspension of the underlying muddy sediments. A comparison of the data between the water and sediment columns shows that the excess of 210 Po found in the water body could be balanced by only a small amount of deficit of 210 Po in the sediment, due to the characteristics of this continental shelf area. (author)

  9. Eddy-induced cross-shelf export of high Chl-a coastal waters in the SE Bay of Biscay

    KAUST Repository

    Rubio, Anna

    2017-12-08

    Different remote sensing data were combined to characterise a winter anticyclonic eddy in the southeastern Bay of Biscay and to infer its effects on cross-shelf exchanges, in a period when typical along shelf-slope currents depict a cyclonic pattern. While the joint analysis of available satellite data (infrared, visible and altimetry) permitted the characterisation and tracking of the anticyclone properties and path, data from a coastal high-frequency radar system enabled a quantitative analysis of the surface cross-shelf transports associated with this anticyclone. The warm core anticyclone had a diameter of around 50km, maximum azimuthal velocities near 50cms−1 and a relative vorticity of up to −0.45f. The eddy generation occurred after the relaxation of a cyclonic wind-driven current regime over the shelf-slope; then, the eddy remained stationary for several weeks until it started to drift northwards along the shelf break. The surface signature of this eddy was observed by means of high-frequency radar data for 20 consecutive days, providing a unique opportunity to characterise and quantify, from a Lagrangian perspective, the associated transport and its effect on the Chl-a surface distribution. We observed the presence of mesoscale structures with similar characteristics in the area during different winters within the period 2011–2014. Our results suggest that the eddy-induced recurrent cross-shelf export is an effective mechanism for the expansion of coastal productive waters into the adjacent oligotrophic ocean basin.

  10. Seasonal and inter-annual temperature variability in the bottom waters over the western Black Sea shelf

    Directory of Open Access Journals (Sweden)

    G. I. Shapiro

    2011-09-01

    Full Text Available Long-term changes in the state of the Bottom Shelf Water (BSW on the Western shelf of the Black Sea are assessed using analysis of intra-seasonal and inter-annual temperature variations. For the purpose of this study the BSW is defined as such shelf water mass between the seabed and the upper mixed layer (bounded by the σθ = 14.2 isopycnal which has limited ability to mix vertically with oxygen-rich surface waters during the warm season due to formation of a seasonal pycnocline. A long-term time series of temperature anomalies in the BSW is constructed from in-situ observations taken over the 2nd half of the 20th century. The BSW is shown to occupy nearly half of the shelf area during the summer stratification period (May–November.The results reveal a warm phase in the 1960s/70s, followed by a cold phase between 1985 and 1995 and a further warming after 1995. The transition between the warm and cold periods coincides with a regime shift in the Black Sea ecosystem. While it was confirmed that the memory of winter convection is well preserved over the following months in the deep sea, the signal of winter cooling in the BSW significantly reduces during the warm season. The potential of the BSW to ventilate horizontally during the warm season with the deep-sea waters is assessed using isopycnic analysis of temperature variations. It is shown that temperature in the BSW is stronger correlated with the temperature of Cold Intermediate Waters (CIW in the deep sea than with the severity of the previous winters, thus indicating that the isopycnal exchanges with the deep sea are more important for inter-annual/inter-decadal variability of the BSW on the western Black Sea shelf than effects of winter convection on the shelf itself.

  11. Influence of cross-shelf water transport on nutrients and phytoplankton in the East China Sea: a model study

    Directory of Open Access Journals (Sweden)

    L. Zhao

    2011-01-01

    Full Text Available A three dimensional coupled biophysical model was used to examine the supply of oceanic nutrients to the shelf of the East China Sea (ECS and its role in primary production over the shelf. The model consisted of two parts: the hydrodynamic module was based on a nested model with a horizontal resolution of 1/18 degree, whereas the biological module was a lower trophic level ecosystem model including two types of phytoplankton, three elements of nutrients, and biogenic organic material. The model results suggested that seasonal variations occurred in the distribution of nutrients and chlorophyll a over the shelf of the ECS. After comparison with available observed nutrients and chlorophyll a data, the model results were used to calculate volume and nutrients fluxes across the shelf break. The annual mean total fluxes were 1.53 Sv for volume, 9.4 kmol s−1 for DIN, 0.7 kmol s−1 for DIP, and 18.2 kmol s−1 for silicate. Two areas, northeast of Taiwan and southwest of Kyushu, were found to be major source regions of oceanic nutrients to the shelf. Although the onshore fluxes of nutrients and volume both had apparent seasonal variations, the seasonal variation of the onshore nutrient flux did not exactly follow that of the onshore volume flux. Additional calculations in which the concentration of nutrients in Kuroshio water was artificially increased suggested that the oceanic nutrients were distributed in the bottom layer from the shelf break to the region offshore of the Changjiang estuary from spring to summer and appeared in the surface layer from autumn to winter. The calculations also implied that the supply of oceanic nutrients to the shelf can change the consumption of pre-existing nutrients from rivers. The response of primary production over the shelf to the oceanic nutrients was confirmed not only in the surface layer (mainly at the outer shelf and shelf break in winter and in the region

  12. Nitrogen and phosphorus in cascade multi-system tropical reservoirs: water and sediment

    Directory of Open Access Journals (Sweden)

    Pompêo Marcelo

    2017-09-01

    Full Text Available The aim of this research was to analyze the horizontal spatial heterogeneity of both water and superficial sediment quality among and within the reservoirs of the Cantareira System (CS, focusing on concentrations of N and P, attributed to the dumping of raw domestic sewage into water bodies, which is the main cause of water pollution in São Paulo State (Brazil. The CS is a multi-system complex composed of five interconnected reservoirs, with water transported by gravity through 48 km of tunnels and channels. From the last reservoir of the CS, with an output of 33 m3 s−1, the water is conducted to a water treatment plant, producing half of the water consumed by 19 million people inhabiting São Paulo city. The upstream reservoirs are more eutrophic than the downstream ones. Data also suggest that the low phytoplankton biomass (ranging from 0.9 to 14.4 μg dm−3 is regulated by the low nutrient availability, mainly of phosphorus (TP ranging from below the detection limit, <9.0 μg dm−3, to 47.3 μg dm−3. For water, the DIN/TP ratios values range from 19 to 380. The upstream reservoirs function as nutrient accumulators and the sediment is the main compartment in which P and N are stored. Although the reservoirs are located in different river basins and are not in sequence along the same river, the results suggest a marked gradient between the reservoirs, with features similar to those of cascade reservoirs. The large volumes flowing through the canals and tunnels could explain the observed pattern. The CS reservoirs can therefore be considered multi-system reservoirs in cascade, constituting a particular case of multi-system reservoirs.

  13. Eddy-induced cross-shelf export of high Chl-a coastal waters in the SE Bay of Biscay

    KAUST Repository

    Rubio, Anna; Caballero, Ainhoa; Orfila, Alejandro; Herná ndez-Carrasco, Ismael; Ferrer, Luis; Gonzá lez, Manuel; Solabarrieta, Lohitzune; Mader, Julien

    2017-01-01

    with similar characteristics in the area during different winters within the period 2011–2014. Our results suggest that the eddy-induced recurrent cross-shelf export is an effective mechanism for the expansion of coastal productive waters into the adjacent

  14. Abundant plankton-sized microplastic particles in shelf waters of the northern Gulf of Mexico.

    Science.gov (United States)

    Di Mauro, Rosana; Kupchik, Matthew J; Benfield, Mark C

    2017-11-01

    Accumulation of marine debris is a global problem that affects the oceans on multiple scales. The majority of floating marine debris is composed of microplastics: plastic particles up to 5 mm in diameter. With similar sizes and appearances to natural food items, these small fragments pose potential risks to many marine organisms including zooplankton and zooplanktivores. Semi-enclosed seas are reported to have high concentrations of microplastics, however, the distribution and concentration of microplastics in one such system, the Gulf of Mexico, remains unknown. Our study documented and characterized microplastics in continental shelf waters off the Louisiana coast in the northern Gulf of Mexico, using bongo nets, neuston nets, and Niskin bottles. Additionally, we compared the size distributions of microplastics and zooplankton collected using the nets. Plastics were manually sorted from the samples, documented, and measured using digital microscopy. Confirmation of putative plastics was carried out by hydrofluoric acid digestion and a subsample was analyzed using FTIR microscopy. Estimated concentrations of microplastics collected on the inner continental shelf during this study are among the highest reported globally. Total microplastic concentrations ranged from 4.8 to 8.2 particles m -3 and 5.0-18.4 particles m -3 for the bongo and neuston samples, respectively. Niskin bottles collected smaller plastic particles than the nets and indicated total microplastic concentrations (primarily fibers) from 6.0E4 - 15.7E4 particles m -3 . Microplastic concentrations were greater than the abundances of all but four of the five most abundant taxa from bongo nets and were not statistically different from the abundances of any of the most numerous taxa from neuston nets. Sizes of microplastics and zooplankton partially or completely overlapped, suggesting the potential for confusion with natural prey. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Water Mass Classification on a Highly Variable Arctic Shelf Region: Origin of Laptev Sea Water Masses and Implications for the Nutrient Budget

    Science.gov (United States)

    Bauch, D.; Cherniavskaia, E.

    2018-03-01

    Large gradients and inter annual variations on the Laptev Sea shelf prevent the use of uniform property ranges for a classification of major water masses. The central Laptev Sea is dominated by predominantly marine waters, locally formed polynya waters and riverine summer surface waters. Marine waters enter the central Laptev Sea from the northwestern Laptev Sea shelf and originate from the Kara Sea or the Arctic Ocean halocline. Local polynya waters are formed in the Laptev Sea coastal polynyas. Riverine summer surface waters are formed from Lena river discharge and local melt. We use a principal component analysis (PCA) in order to assess the distribution and importance of water masses within the Laptev Sea. This mathematical method is applied to hydro-chemical summer data sets from the Laptev Sea from five years and allows to define water types based on objective and statistically significant criteria. We argue that the PCA-derived water types are consistent with the Laptev Sea hydrography and indeed represent the major water masses on the central Laptev Sea shelf. Budgets estimated for the thus defined major Laptev Sea water masses indicate that freshwater inflow from the western Laptev Sea is about half or in the same order of magnitude as freshwater stored in locally formed polynya waters. Imported water dominates the nutrient budget in the central Laptev Sea; and only in years with enhanced local polynya activity is the nutrient budget of the locally formed water in the same order as imported nutrients.

  16. Restoration of parameters of high-energy cascades in Cherenkov water calorimeter with a dense array of quasispherical modules

    International Nuclear Information System (INIS)

    Khomyakov, V. A.; Bogdanov, A. G.; Kindin, V. V.; Kokoulin, R. P.; Petrukhin, A. A.; Khokhlov, S. S.; Shutenko, V. V.; Yashin, I. I.

    2015-01-01

    A problem concerning the restoration of the parameters of a cascade shower with an unknown axis originating by muons in a Cherenkov water calorimeter is considered. A method for estimating the direction and geometric position of the cascade’s axis, which is based on the analysis of responses of quasispherical modules, and the criteria of selection of the events with cascades among the events with a large energy liberation are proposed. The method and the criteria are tested on events with cascades generated by near-horizontal muons of high energies detected by a DECOR coordinate-track detector. The preliminary results of measurements of the energy spectrum of cascade showers are presented

  17. Intense Undular Bores on the Autumn Pycnocline of Shelf Waters of the Peter the Great Bay (Sea of Japan)

    Science.gov (United States)

    Dolgikh, G. I.; Novotryasov, V. V.; Yaroshchuk, I. O.; Permyakov, M. S.

    2018-03-01

    The results of field observations of an internal undular bore that were performed in a coastal zone of constant depth in the Sea of Japan are presented. A hydrodynamic model of undular bores is discussed according to which the recorded disturbances of the water medium are an experimental prototype of strongly nonlinear (intense) internal undular bores on the pycnocline of shelf waters of Peter the Great Bay with an intensity close to the limit.

  18. Salt stabilizer for preventing chlorine depletion and increasing shelf-life of potable water - A concept

    Science.gov (United States)

    Copeland, E. J.; Edgerley, R. H.

    1971-01-01

    Proposed concept, based on law of mass action uses addition of salt to increase chlorine ions produced in sodium hydrochlorite solutions, thereby increasing solution shelf-life. This technique is not costly. Usefulness will be determined by acceptability of salt in product undergoing long shelf-life.

  19. Sup(239,240)Pu in estuarine and shelf waters of the north-eastern United States

    International Nuclear Information System (INIS)

    Sholkovitz, E.R.; Mann, D.R.

    1987-01-01

    The distribution of sup(239,240)Pu between dissolved and particulate forms has been measured in four estuaries on the north-east coast of the United States (Connecticut River, Delaware Bay, Chesapeake Bay, and Mullica River). The data cover the whole salinity range from freshwater input to shelf waters at 3.5% and includes one profile from a nearly anoxic basin in the Chesapeake Bay. In the organic-rich Mullica River estuary, large-scale removal of riverine dissolved sup(239,240)Pu occurs at low salinities due to salt-induced coagulation, a mechanism analogous to that for iron and humic acids. Within the 0 to 2.5-3.5% zone in the other three estuaries, the activity of dissolved sup(239,240)Pu increases almost conservatively. The activities of particulate sup(239,240)Pu are highest in the more turbid waters of low salinity regime (0-1.5%), but become increasingly insignificant with respect to dissolved sup(239,240)Pu as salinities increase. At higher salinities corresponding to shelf water, there is a sharp increase in dissolved sup(239,240)Pu activity. The dissolved sup(239,240)Pu activity within each estuary appears to be inversely related to the flushing time of water. The sharp decrease in dissolved sup(239,240)Pu activities between shelf and estuarine waters appears to be driven by removal within the estuaries themselves rather than on the shelf. Dissolved sup(239,240)Pu activities are lower in the nearly-anoxic bottom waters of Chesapeake Bay indicating enhanced removal by redox transformation of Pu [i.e., Pu(V) to Pu(IV)]. (author)

  20. Summertime calcium carbonate undersaturation in shelf waters of the western Arctic Ocean – how biological processes exacerbate the impact of ocean acidification

    OpenAIRE

    N. R. Bates; M. I. Orchowska; R. Garley; J. T. Mathis

    2013-01-01

    The Arctic Ocean accounts for only 4% of the global ocean area, but it contributes significantly to the global carbon cycle. Recent observations of seawater CO2-carbonate chemistry in shelf waters of the western Arctic Ocean, primarily in the Chukchi Sea, from 2009 to 2011 indicate that bottom waters are seasonally undersaturated with respect to calcium carbonate (CaCO3) minerals, particularly aragonite. Nearly 40% of sampled bottom waters on the shelf have saturation states...

  1. Water, ice, and meteorological measurements at South Cascade glacier, Washington, balance year 2003

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2005-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance year 2003. The 2003 glacier-average maximum winter snow balance was 2.66 meters water equivalent, which was about equal to the average of such balances for the glacier since balance year 1959. The 2003 glacier summer balance (-4.76 meters water equivalent) was the most negative reported for the glacier, and the 2003 net balance (-2.10 meters water equivalent), was the second-most negative reported. The glacier 2003 annual (water year) balance was -1.89 meters water equivalent. The area of the glacier near the end of the balance year was 1.89 square kilometers, a decrease of 0.03 square kilometer from the previous year. The equilibrium-line altitude was higher than any part of the glacier; however, because snow remained along part of one side of the upper glacier, the accumulation-area ratio was 0.07. During September 13, 2002-September 13, 2003, the glacier terminus retreated at a rate of about 15 meters per year. Average speed of surface ice, computed using a series of vertical aerial photographs dating back to 2001, ranged from 2.2 to 21.8 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin was gaged during part of water year 2003. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed, and incoming solar radiation were measured at selected locations on and near the glacier. Summer 2003 at the glacier was among the warmest for which data are available.

  2. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, balance year 2002

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2004-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance year 2002. The 2002 glacier-average maximum winter snow balance was 4.02 meters, the second largest since 1959. The 2002 glacier summer, net, and annual (water year) balances were -3.47, 0.55, and 0.54 meters, respectively. The area of the glacier near the end of the balance year was 1.92 square kilometers, and the equilibrium-line altitude and the accumulation area ratio were 1,820 meters and 0.84, respectively. During September 20, 2001 to September 13, 2002, the terminus retreated 4 meters, and computed average ice speeds in the ablation area ranged from 7.8 to 20.7 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin were measured during part of the 2002 water year. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed and incoming solar radiation were measured at selected locations near the glacier.

  3. Dissolved iron in the Arctic shelf seas and surface waters of the central Arctic Ocean : Impact of Arctic river water and ice-melt

    NARCIS (Netherlands)

    Klunder, M. B.; Bauch, D.; Laan, P.; de Baar, H. J. W.; van Heuven, S.; Ober, S.

    2012-01-01

    Concentrations of dissolved (10 nM) in the bottom waters of the Laptev Sea shelf may be attributed to either sediment resuspension, sinking of brine or regeneration of DFe in the lower layers. A significant correlation (R-2 = 0.60) between salinity and DFe is observed. Using delta O-18, salinity,

  4. Forecasting water demand using back propagation networks in the operation of reservoirs in the citarum cascade, west java, indonesia

    Directory of Open Access Journals (Sweden)

    Mulya R. Mashudi

    2017-11-01

    Full Text Available This study investigates the use of Neural Networks (NN as a potential means of more accurately forecasting water demand in the Citarum River basin cascade. Neural Networks have the ability to recognise nonlinear patterns when sufficiently trained with historical data. The study constructs a NN model of the cascade, based on Back Propagation Networks (BPN. Data representing physical characteristics and meteorological conditions in the Citarum River basin from 1989 through 1995 were used to train the BPN. Nonlinear activation functions (sigmoid, tangent, and gaussian functions and hidden layers in the BPN were chosen for the study.

  5. Cascading water underneath Wilkes Land, East Antarctic ice sheet, observed using altimetry and digital elevation models

    Science.gov (United States)

    Flament, T.; Berthier, E.; Rémy, F.

    2014-04-01

    We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyse the event, we combined altimetry data from several sources and subglacial topography. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM) derived from ASTER and SPOT5 stereo imagery acquired in January 2006 and February 2012. At 5.2 ± 1.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry spanning 2003-2009 and the SPOT5 DEM indicate that the discharge started in November 2006 and lasted approximately 2 years. A 13 m uplift of the surface, corresponding to a refilling of about 0.6 ± 0.3 km3, was observed between the end of the discharge in October 2008 and February 2012. Using the 35-day temporal resolution of Envisat radar altimetry, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream of CookE2. The total volume of water traveling within the theoretical 500-km-long flow paths computed with the BEDMAP2 data set is similar to the volume that drained from Lake CookE2, and our observations suggest that most of the water released from Lake CookE2 did not reach the coast but remained trapped underneath the ice sheet. Our study illustrates how combining multiple remote sensing techniques allows monitoring of the timing and magnitude of subglacial water flow beneath the East Antarctic ice sheet.

  6. Arctic Ocean outflow and glacier–ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland

    Directory of Open Access Journals (Sweden)

    I. A. Dmitrenko

    2017-12-01

    Full Text Available The first-ever conductivity–temperature–depth (CTD observations on the Wandel Sea shelf in northeastern Greenland were collected in April–May 2015. They were complemented by CTDs taken along the continental slope during the Norwegian FRAM 2014–2015 drift. The CTD profiles are used to reveal the origin of water masses and interactions with ambient water from the continental slope and the tidewater glacier outlet. The subsurface water is associated with the Pacific water outflow from the Arctic Ocean. The underlying halocline separates the Pacific water from a deeper layer of polar water that has interacted with the warm Atlantic water outflow through the Fram Strait, recorded below 140 m. Over the outer shelf, the halocline shows numerous cold density-compensated intrusions indicating lateral interaction with an ambient polar water mass across the continental slope. At the front of the tidewater glacier outlet, colder and turbid water intrusions were observed at the base of the halocline. On the temperature–salinity plots these stations indicate a mixing line that is different from the ambient water and seems to be conditioned by the ocean–glacier interaction. Our observations of Pacific water are set within the context of upstream observations in the Beaufort Sea and downstream observations from the Northeast Water Polynya, and clearly show the modification of Pacific water during its advection across the Arctic Ocean. Moreover, ambient water over the Wandel Sea slope shows different thermohaline structures indicating the different origin and pathways of the on-shore and off-shore branches of the Arctic Ocean outflow through the western Fram Strait.

  7. Arctic Ocean outflow and glacier-ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland)

    Science.gov (United States)

    Dmitrenko, Igor A.; Kirillov, Sergey A.; Rudels, Bert; Babb, David G.; Toudal Pedersen, Leif; Rysgaard, Søren; Kristoffersen, Yngve; Barber, David G.

    2017-12-01

    The first-ever conductivity-temperature-depth (CTD) observations on the Wandel Sea shelf in northeastern Greenland were collected in April-May 2015. They were complemented by CTDs taken along the continental slope during the Norwegian FRAM 2014-2015 drift. The CTD profiles are used to reveal the origin of water masses and interactions with ambient water from the continental slope and the tidewater glacier outlet. The subsurface water is associated with the Pacific water outflow from the Arctic Ocean. The underlying halocline separates the Pacific water from a deeper layer of polar water that has interacted with the warm Atlantic water outflow through the Fram Strait, recorded below 140 m. Over the outer shelf, the halocline shows numerous cold density-compensated intrusions indicating lateral interaction with an ambient polar water mass across the continental slope. At the front of the tidewater glacier outlet, colder and turbid water intrusions were observed at the base of the halocline. On the temperature-salinity plots these stations indicate a mixing line that is different from the ambient water and seems to be conditioned by the ocean-glacier interaction. Our observations of Pacific water are set within the context of upstream observations in the Beaufort Sea and downstream observations from the Northeast Water Polynya, and clearly show the modification of Pacific water during its advection across the Arctic Ocean. Moreover, ambient water over the Wandel Sea slope shows different thermohaline structures indicating the different origin and pathways of the on-shore and off-shore branches of the Arctic Ocean outflow through the western Fram Strait.

  8. The Effect of Alongcoast Advection on Pacific Northwest Shelf and Slope Water Properties in Relation to Upwelling Variability

    Science.gov (United States)

    Stone, Hally B.; Banas, Neil S.; MacCready, Parker

    2018-01-01

    The Northern California Current System experiences highly variable seasonal upwelling in addition to larger basin-scale variability, both of which can significantly affect its water chemistry. Salinity and temperature fields from a 7 year ROMS hindcast model of this region (43°N-50°N), along with extensive particle tracking, were used to study interannual variability in water properties over both the upper slope and the midshelf bottom. Variation in slope water properties was an order of magnitude smaller than on the shelf. Furthermore, the primary relationship between temperature and salinity anomalies in midshelf bottom water consisted of variation in density (cold/salty versus warm/fresh), nearly orthogonal to the anomalies along density levels (cold/fresh versus warm/salty) observed on the upper slope. These midshelf anomalies were well-explained (R2 = 0.6) by the combination of interannual variability in local and remote alongshore wind stress, and depth of the California Undercurrent (CUC) core. Lagrangian analysis of upper slope and midshelf bottom water shows that both are affected simultaneously by large-scale alongcoast advection of water through the northern and southern boundaries. The amplitude of anomalies in bottom oxygen and dissolved inorganic carbon (DIC) on the shelf associated with upwelling variability are larger than those associated with typical variation in alongcoast advection, and are comparable to observed anomalies in this region. However, a large northern intrusion event in 2004 illustrates that particular, large-scale alongcoast advection anomalies can be just as effective as upwelling variability in changing shelf water properties on the interannual scale.

  9. Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

    Science.gov (United States)

    Aurin, Dirk Alexander; Mannino, Antonio; Franz, Bryan

    2013-01-01

    Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with

  10. Phytoplankton absorption predicts patterns in primary productivity in Australian coastal shelf waters

    Science.gov (United States)

    Robinson, C. M.; Cherukuru, N.; Hardman-Mountford, N. J.; Everett, J. D.; McLaughlin, M. J.; Davies, K. P.; Van Dongen-Vogels, V.; Ralph, P. J.; Doblin, M. A.

    2017-06-01

    The phytoplankton absorption coefficient (aPHY) has been suggested as a suitable alternate first order predictor of net primary productivity (NPP). We compiled a dataset of surface bio-optical properties and phytoplankton NPP measurements in coastal waters around Australia to examine the utility of an in-situ absorption model to estimate NPP. The magnitude of surface NPP (0.20-19.3 mmol C m-3 d-1) across sites was largely driven by phytoplankton biomass, with higher rates being attributed to the microplankton (>20 μm) size class. The phytoplankton absorption coefficient aPHY for PAR (photosynthetically active radiation; āPHY)) ranged from 0.003 to 0.073 m-1, influenced by changes in phytoplankton community composition, physiology and environmental conditions. The aPHY coefficient also reflected changes in NPP and the absorption model-derived NPP could explain 73% of the variability in measured surface NPP (n = 41; RMSE = 2.49). The absorption model was applied to two contrasting coastal locations to examine NPP dynamics: a high chlorophyll-high variation (HCHV; Port Hacking National Reference Station) and moderate chlorophyll-low variation (MCLV; Yongala National Reference Station) location in eastern Australia using the GIOP-DC satellite aPHY product. Mean daily NPP rates between 2003 and 2015 were higher at the HCHV site (1.71 ± 0.03 mmol C m-3 d-1) with the annual maximum NPP occurring during the austral winter. In contrast, the MCLV site annual NPP peak occurred during the austral wet season and had lower mean daily NPP (1.43 ± 0.03 mmol C m-3 d-1) across the time-series. An absorption-based model to estimate NPP is a promising approach for exploring the spatio-temporal dynamics in phytoplankton NPP around the Australian continental shelf.

  11. Effects of the bottom boundary condition in numerical investigations of dense water cascading on a slope

    Science.gov (United States)

    Berntsen, Jarle; Alendal, Guttorm; Avlesen, Helge; Thiem, Øyvind

    2018-05-01

    The flow of dense water along continental slopes is considered. There is a large literature on the topic based on observations and laboratory experiments. In addition, there are many analytical and numerical studies of dense water flows. In particular, there is a sequence of numerical investigations using the dynamics of overflow mixing and entrainment (DOME) setup. In these papers, the sensitivity of the solutions to numerical parameters such as grid size and numerical viscosity coefficients and to the choices of methods and models is investigated. In earlier DOME studies, three different bottom boundary conditions and a range of vertical grid sizes are applied. In other parts of the literature on numerical studies of oceanic gravity currents, there are statements that appear to contradict choices made on bottom boundary conditions in some of the DOME papers. In the present study, we therefore address the effects of the bottom boundary condition and vertical resolution in numerical investigations of dense water cascading on a slope. The main finding of the present paper is that it is feasible to capture the bottom Ekman layer dynamics adequately and cost efficiently by using a terrain-following model system using a quadratic drag law with a drag coefficient computed to give near-bottom velocity profiles in agreement with the logarithmic law of the wall. Many studies of dense water flows are performed with a quadratic bottom drag law and a constant drag coefficient. It is shown that when using this bottom boundary condition, Ekman drainage will not be adequately represented. In other studies of gravity flow, a no-slip bottom boundary condition is applied. With no-slip and a very fine resolution near the seabed, the solutions are essentially equal to the solutions obtained with a quadratic drag law and a drag coefficient computed to produce velocity profiles matching the logarithmic law of the wall. However, with coarser resolution near the seabed, there may be a

  12. Fire and water: volcanology, geomorphology, and hydrogeology of the Cascade Range, central Oregon

    Science.gov (United States)

    Katharine V. Cashman; Natalia I. Deligne; Marshall W. Gannett; Gordon E. Grant; Anne. Jefferson

    2009-01-01

    This field trip guide explores the interactions among the geologic evolution, hydrology, and fluvial geomorphology of the central Oregon Cascade Range. Key topics include the geologic control of hydrologic regimes on both the wet and dry sides of the Cascade Range crest, groundwater dynamics and interaction between surface and groundwater in young volcanic arcs, and...

  13. Complex vertical migration of larvae of the ghost shrimp, Nihonotrypaea harmandi, in inner shelf waters of western Kyushu, Japan

    Science.gov (United States)

    Tamaki, Akio; Mandal, Sumit; Agata, Yoshihiro; Aoki, Ikumi; Suzuki, Toshikazu; Kanehara, Hisao; Aoshima, Takashi; Fukuda, Yasushi; Tsukamoto, Hideshi; Yanagi, Tetsuo

    2010-01-01

    The position of meroplanktonic larvae in the water column with depth-dependent current velocities determines horizontal transport trajectories. For those larvae occurring in inner shelf waters, little is known about how combined diel and tidally-synchronized vertical migration patterns shift ontogenetically. The vertical migration of larvae of Nihonotrypaea harmandi (Decapoda: Thalassinidea: Callianassidae) was investigated in mesotidal, inner shelf waters of western Kyushu, Japan in July-August 2006. The larval sampling at seven depth layers down to 60 m was conducted every 3 h for 36 h in a 68.5-m deep area 10 km off a major coastal adult habitat. Within a 61-65-m deep area 5-7.5 km off the adult habitat, water temperature, salinity, chlorophyll a concentration, and photon flux density were measured, and water currents there were characterized from harmonic analysis of current meter data collected in 2008. The water column was stratified, with pycnocline, chlorophyll a concentration maximum, and 2% of photon flux density at 2 m, recorded at around 22-24 m. The stratified residual currents were detected in their north component, directed offshore and onshore in the upper and lower mixed layers, respectively. More than 87% of larvae occurred between 20 m and 60 m, producing a net onshore transport of approximately 1.3 km d -1. At the sunset flooding tide, all zoeal-stage larvae ascended, which could further promote retention (1.4-km potential onshore transport in 3 h). The actual onshore transport of larvae was detected by observing their occurrence pattern in a shallow embayment area with the adult habitat for 24 h in October 1994. However, ontogenetic differences in the vertical migration pattern in inner shelf waters were also apparent, with the maximum mean positions of zoeae deepening with increasing stages. Zoeae I and II performed a reverse diel migration, with their minimum and maximum depths being reached around noon and midnight, respectively. Zoeae IV

  14. 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

  15. Comparison of grey water treatment performance by a cascading sand filter and a constructed wetland.

    Science.gov (United States)

    Kadewa, W W; Le Corre, K; Pidou, M; Jeffrey, P J; Jefferson, B

    2010-01-01

    A novel unplanted vertical flow subsurface constructed wetland technology comprising three shallow beds (0.6 m length, 0.45 m width and 0.2 m depth) arranged in a cascading series and a standard single-pass Vertical Flow Planted Constructed Wetland (VFPCW, 6 m² and 0.7 m depth) were tested for grey water treatment. Particular focus was on meeting consent for published wastewater reuse parameters and removal of anionic surfactants. Treatment performance at two hydraulic loading rates (HLR) of 0.08, and 0.17 m³ m⁻² d⁻¹ were compared. Both technologies effectively removed more than 90% turbidity and more than 96% for organics with the prototype meeting the most stringent reuse standard of < 2 NTU and <10 mg/L. However, surfactant removal in the VFPCW was higher (76-85%) than in the prototype which only achieved more than 50% removal at higher loading rate. Generally, the prototype performed consistently better than the VFPCW except for surfactant removal. However, at higher loading rates, both systems did not meet the reuse standard of <1 mg L⁻¹ for anionic surfactants. This observation confirms that shallow beds provide a more oxidised environment leading to higher BOD₅ and COD removals. Presence of plants in the VFPCW led to higher anionic surfactant removal, through increased microbial and sorption processes.

  16. Pliocene Te Aute limestones, New Zealand : expanding concepts for cool-water shelf carbonates

    International Nuclear Information System (INIS)

    Nelson, C.S.; Winefield, P.R.; Hood, S.D.; Caron, V.; Pallentin, A.; Kamp, P.J.J.

    2003-01-01

    Acceptance of a spectrum of warm- through cold-water shallow-marine carbonate facies has become of fundamental importance for correctly interpreting the origin and significance of all ancient platform limestones. Among other attributes, properties that have become a hallmark for characterising many Cenozoic non-tropical occurrences include: (1) the presence of common bryozoan and epifaunal bivalve skeletons; (2) a calcite-dominated mineralogy; (3) relatively thin deposits exhibiting low rates of sediment accumulation; (4) an overall destructive early diagenetic regime; and (5) that major porosity destruction and lithification occur mainly in response to chemical compaction of calcitic skeletons during moderate to deep burial. The Pliocene Te Aute limestones are non-tropical skeletal carbonates formed at paleolatitudes near 40-42 degrees S under the influence of commonly strong tidal flows along the margins of an actively deforming and differentially uplifting forearc basin seaway, immediately inboard of the convergent Pacific-Australian plate boundary off eastern North Island, New Zealand. This dynamic depositional and tectonic setting strongly influenced both the style and subsequent diagenetic evolution of the limestones. Some of the Te Aute limestones exhibit the above kinds of 'normal' non-tropical characteristics, but others do not. For example, many are barnacle and/or bivalve dominated, and several include attributes that at least superficially resemble properties of certain tropical carbonates. In this regard, a number of the limestones are infaunal bivalve rich and dominated by an aragonite over a calcite primary mineralogy, with consequently relatively high diagenetic potential. Individual limestone units are also often rather thick (e.g., up to 50-300 m), with accumulation rates from 0.2 to 0.5 m/ka, and locally as high as 1 m/ka. Moreover, there can be a remarkable array of diagenetic features in the limestones, involving grain alteration and

  17. Acoustic Estimates of Distribution and Biomass of Different Acoustic Scattering Types Between the New England Shelf Break and Slope Waters

    KAUST Repository

    McLaren, Alexander

    2011-11-01

    Due to their great ecological significance, mesopelagic fishes are attracting a wider audience on account of the large biomass they represent. Data from the National Marine Fisheries Service (NMFS) provided the opportunity to explore an unknown region of the North-West Atlantic, adjacent to one of the most productive fisheries in the world. Acoustic data collected during the cruise required the identification of acoustically distinct scattering types to make inferences on the migrations, distributions and biomass of mesopelagic scattering layers. Six scattering types were identified by the proposed method in our data and traces their migrations and distributions in the top 200m of the water column. This method was able to detect and trace the movements of three scattering types to 1000m depth, two of which can be further subdivided. This process of identification enabled the development of three physically-derived target-strength models adapted to traceable acoustic scattering types for the analysis of biomass and length distribution to 1000m depth. The abundance and distribution of acoustic targets varied closely in relation to varying physical environments associated with a warm core ring in the New England continental Shelf break region. The continental shelf break produces biomass density estimates that are twice as high as the warm core ring and the surrounding continental slope waters are an order of magnitude lower than either estimate. Biomass associated with distinct layers is assessed and any benefits brought about by upwelling at the edge of the warm core ring are shown not to result in higher abundance of deepwater species. Finally, asymmetric diurnal migrations in shelf break waters contrasts markedly with the symmetry of migrating layers within the warm ring, both in structure and density estimates, supporting a theory of predatorial and nutritional constraints to migrating pelagic species.

  18. Assessment of MODIS-Aqua chlorophyll-a algorithms in coastal and shelf waters of the eastern Arabian Sea

    Science.gov (United States)

    Tilstone, Gavin H.; Lotliker, Aneesh A.; Miller, Peter I.; Ashraf, P. Muhamed; Kumar, T. Srinivasa; Suresh, T.; Ragavan, B. R.; Menon, Harilal B.

    2013-08-01

    The use of ocean colour remote sensing to facilitate the monitoring of phytoplankton biomass in coastal waters is hampered by the high variability in absorption and scattering from substances other than phytoplankton. The eastern Arabian Sea coastal shelf is influenced by river run-off, winter convection and monsoon upwelling. Bio-optical parameters were measured along this coast from March 2009 to June 2011, to characterise the optical water type and validate three Chlorophyll-a (Chla) algorithms applied to Moderate Resolution Imaging Spectroradiometer on Aqua (MODIS-Aqua) data against in situ measurements. Ocean Colour 3 band ratio (OC3M), Garver-Siegel-Maritorena Model (GSM) and Generalized Inherent Optical Property (GIOP) Chla algorithms were evaluated. OC3M performed better than GSM and GIOP in all regions and overall, was within 11% of in situ Chla. GSM was within 24% of in situ Chla and GIOP on average was 55% lower. OC3M was less affected by errors in remote sensing reflectance Rrs(λ) and by spectral variations in absorption coefficient (aCDOM(λ)) of coloured dissolved organic material (CDOM) and total suspended matter (TSM) compared to the other algorithms. A nine year Chla time series from 2002 to 2011 was generated to assess regional differences between OC3M and GSM. This showed that in the north eastern shelf, maximum Chla occurred during the winter monsoon from December to February, where GSM consistently gave higher Chla compared to OC3M. In the south eastern shelf, maximum Chla occurred in June to July during the summer monsoon upwelling, and OC3M yielded higher Chla compared to GSM. OC3M currently provides the most accurate Chla estimates for the eastern Arabian Sea coastal waters.

  19. Hydrocarbon production forecast for committed assets in the shallow water Outer Continental Shelf of the Gulf of Mexico

    International Nuclear Information System (INIS)

    Kaiser, Mark J.

    2009-01-01

    In 2007, the federal waters of the Gulf of Mexico averaged daily production of 1.3 million barrels of oil and 7.6 billion cubic feet of natural gas. The majority of oil is produced from deepwater fields in water depth greater than 1000 ft, while most gas production is extracted from the shelf. The Outer Continental Shelf is a mature province with over 3800 fixed structures and 6500 producing wells connected into an integrated pipeline network more than 30,000 miles in length. The purpose of this paper is to develop a methodology to forecast oil and gas production in the shallow water Gulf of Mexico. Structures are categorized according to age and production characteristics, and forecast procedures for each asset class are described and illustrated. The methodology is implemented using the inventory of committed assets circa December 2006. The expected amount of hydrocarbon production arising from the inventory of committed assets under stable reservoir and investment conditions is estimated to be 1056 MMbbl oil and 13.3 Tcf gas valued between $85 and 150 billion. The results of generalized regression models are presented with a discussion of the limitations of analysis. (author)

  20. Effects of electron beam irradiation combined with hot water immersion treatment for shelf life extension of bananas

    International Nuclear Information System (INIS)

    Russly Abdul Rahman

    1996-01-01

    A study of the effects of minimal processing treatments, both individually or in combinations, was carried out in order to extend the shelf life and to improve the quality of bananas. Pre climacteric bananas at light full three-quarter grade, were either treated with hot water immersion for 1-30 min at 45-55 degree C, or irradiated with electron beams (2.0 MeV, Van de Graaff accelerator), to a dose of 0.1-1.5 kGy. All fruit was stored at 21 ± 1 degree C and relative humidity of 85-95 %. There was no significant delay in ripening of fruit treated with hot water immersion at the above temperatures. Some damage to fruit particularly peel scalding at ends occurred at the higher temperatures (>50 degree C). The 50 degree C, 5 minutes immersion was selected for further study. Irradiation to 0.1-0.3 kGy delayed the ripening (up to 3 days) without affecting fruit quality. Doses greater than 0.4 kGy resulted in extensive discoloration and fruit splitting. No significant differences could be detected organoleptically between bananas irradiated at 0.15 kGy and the control. Results of the physico-chemical attributes of the bananas were reported for fruits at colour stage 5 and after 10 and 15 days of storage. The combination treatment of hot water immersion and irradiation at the above settings further extended the shelf life of the banana fruits

  1. Benthic iron and phosphorus release from river dominated shelf sediments under varying bottom water O2 concentrations.

    Science.gov (United States)

    Ghaisas, N. A.; Maiti, K.; White, J. R.

    2017-12-01

    Phosphorus (P) cycling in coastal ocean is predominantly controlled by river discharge and biogeochemistry of the sediments. In coastal Louisiana, sediment biogeochemistry is strongly influenced by seasonally fluctuating bottom water O2, which, in turn transitions the shelf sediments from being a sink to source of P. Sediment P-fluxes were 9.73 ± 0.76 mg / m2 /d and 0.67±0.16 mg/m2/d under anaerobic and aerobic conditions respectively, indicating a 14 times higher P-efflux from oxygen deprived sediments. A high sedimentary oxygen consumption rate of 889 ± 33.6 mg/m2/d was due to organic matter re-mineralization and resulted in progressively decreasing the water column dissolved O2 , coincident with a P-flux of 7.2 ± 5.5 mg/m2/d from the sediment. Corresponding water column flux of Fe total was 19.7 ± 7.80 mg/m2/d and the sediment-TP decreased from 545 mg/Kg to 513 mg/Kg. A simultaneous increase in pore water Fe and P concentrations in tandem with a 34.6% loss in sedimentary Fe-bound P underscores the importance of O2 on coupled Fe- P biogeochemistry. This study suggests that from a 14,025 sq. km hypoxia area, Louisiana shelf sediments can supply 1.33x105 kg P/day into the water column compared to 0.094 x 105 kg P/day during the fully aerobic water column conditions.

  2. The Deposition and Accumulation of Microplastics in Marine Sediments and Bottom Water from the Irish Continental Shelf.

    Science.gov (United States)

    Martin, Jake; Lusher, Amy; Thompson, Richard C; Morley, Audrey

    2017-09-07

    Microplastics are widely dispersed throughout the marine environment. An understanding of the distribution and accumulation of this form of pollution is crucial for gauging environmental risk. Presented here is the first record of plastic contamination, in the 5 mm-250 μm size range, of Irish continental shelf sediments. Sixty-two microplastics were recovered from 10 of 11 stations using box cores. 97% of recovered microplastics were found to reside shallower than 2.5 cm sediment depth, with the area of highest microplastic concentration being the water-sediment interface and top 0.5 cm of sediments (66%). Microplastics were not found deeper than 3.5 ± 0.5 cm. These findings demonstrate that microplastic contamination is ubiquitous within superficial sediments and bottom water along the western Irish continental shelf. Results highlight that cores need to be at least 4-5 cm deep to quantify the standing stock of microplastics within marine sediments. All recovered microplastics were classified as secondary microplastics as they appear to be remnants of larger items; fibres being the principal form of microplastic pollution (85%), followed by broken fragments (15%). The range of polymer types, colours and physical forms recovered suggests a variety of sources. Further research is needed to understand the mechanisms influencing microplastic transport, deposition, resuspension and subsequent interactions with biota.

  3. Does Arctic sea ice reduction foster shelf-basin exchange?

    Science.gov (United States)

    Ivanov, Vladimir; Watanabe, Eiji

    2013-12-01

    The recent shift in Arctic ice conditions from prevailing multi-year ice to first-year ice will presumably intensify fall-winter sea ice freezing and the associated salt flux to the underlying water column. Here, we conduct a dual modeling study whose results suggest that the predicted catastrophic consequences for the global thermohaline circulation (THC), as a result of the disappearance of Arctic sea ice, may not necessarily occur. In a warmer climate, the substantial fraction of dense water feeding the Greenland-Scotland overflow may form on Arctic shelves and cascade to the deep basin, thus replenishing dense water, which currently forms through open ocean convection in the sub-Arctic seas. We have used a simplified model for estimating how increased ice production influences shelf-basin exchange associated with dense water cascading. We have carried out case studies in two regions of the Arctic Ocean where cascading was observed in the past. The baseline range of buoyancy-forcing derived from the columnar ice formation was calculated as part of a 30-year experiment of the pan-Arctic coupled ice-ocean general circulation model (GCM). The GCM results indicate that mechanical sea ice divergence associated with lateral advection accounts for a significant part of the interannual variations in sea ice thermal production in the coastal polynya regions. This forcing was then rectified by taking into account sub-grid processes and used in a regional model with analytically prescribed bottom topography and vertical stratification in order to examine specific cascading conditions in the Pacific and Atlantic sectors of the Arctic Ocean. Our results demonstrate that the consequences of enhanced ice formation depend on geographical location and shelf-basin bathymetry. In the Pacific sector, strong density stratification in slope waters impedes noticeable deepening of shelf-origin water, even for the strongest forcing applied. In the Atlantic sector, a 1.5x increase of

  4. Changes in water mass exchange between the NW shelf areas and the North Atlantic and their impact on nutrient/carbon cycling

    Science.gov (United States)

    Gröger, Matthias; Maier-Reimer, Ernst; Mikolajewicz, Uwe; Segschneider, Joachim; Sein, Dimitry

    2010-05-01

    Despite their comparatively small extension on a global scale, shelf areas are of interest for several economic reasons and climatic processes related to nutrient cycling, sea food supply, and biological productivity. Moreover, they constitute an important interface for nutrients, pollutants and freshwater on their pathway from the continents to the open ocean. This modelling study aims to investigate the spatial and temporal variability of water mass exchange between the North Atlantic and the NW European shelf and their impact on nutrient/carbon cycling and biological productivity. For this, a new modeling approach has been set up which bridges the gap between pure shelf models where water mass transports across the model domain too strongly depend on the formulation of open boundaries and global models suffering under their too coarse resolution in shelf regions. The new model consists of the global ocean and carbon cycle model MPIOM/HAMOCC with strongly increased resolution in the North Sea and the North Atlantic coupled to the regional atmosphere model REMO. The model takes the full luni-solar tides into account. It includes further a 12 layer sediment module with the relevant pore water chemistry. The main focus lies on the governing mechanisms of water mass exchange across the shelf break and the imprint on shelf biogeochemistry. For this, artificial tracers with a prescribed decay rate have been implemented to distinguish waters arriving from polar and shelf regions and those that originate from the tropics. Experiments were carried out for the years 1948 - 2007. The relationship to larger scale circulation patterns like the position and variability of the subtropical and subpolar gyres is analyzed. The water mass exchange is analyzed with respect to the nutrient concentration and productivity on the European shelf areas. The implementation of tides leads to an enhanced vertical mixing which causes lower sea surface temperatures compared to simulations

  5. Morphology and sediment dynamics of the northern Catalan continental shelf, northwestern Mediterranean Sea

    Science.gov (United States)

    Durán, Ruth; Canals, Miquel; Sanz, José Luis; Lastras, Galderic; Amblas, David; Micallef, Aaron

    2014-01-01

    The northern Catalan continental shelf, in the northwestern Mediterranean Sea, extends along 200 km from the Cap de Creus submarine canyon to the Llobregat Delta, in the vicinity of the city of Barcelona. In this paper we present the results of a systematic investigation of this area by means of very high-resolution multibeam bathymetry to fully assess its morphological variability. The causative factors and processes determining such variability are subsequently interpreted. The shelf is divided in three segments by two prominent submarine canyons: the northernmost Roses Shelf is separated from the intermediate La Planassa Shelf by the La Fonera Canyon, while the boundary between the La Planassa Shelf and the southernmost Barcelona Shelf is marked by the Blanes Canyon. These two canyons are deeply incised in the continental margin, with their heads located at only 0.8 and 5 km from the shore, respectively. The seafloor character reflects the influence of external controlling factors on the geomorphology and sediment dynamics of the northern continental shelf of Catalonia. These factors are the geological setting, the volume and nature of sediment input, and the type and characteristics of processes leading to sediment redistribution, such as dense shelf water cascading (DSWC) and eastern storms. The interaction of all these factors determines sediment dynamics and allows subdividing the northern Catalan continental shelf into three segments: the erosional-depositional Roses Shelf to the north, the non-depositional La Planassa Shelf in the middle, and the depositional Barcelona Shelf to the south. Erosional features off the Cap de Creus Peninsula and an along-shelf subdued channel in the outer shelf illustrate prevailing sediment dynamics in the Roses segment, which is dominated by erosional processes, local sediment accumulations and the southward bypass of sediment. The rocky character of the seafloor immediately north of the Blanes Canyon head demonstrates that

  6. Animal water balance drives top-down effects in a riparian forest-implications for terrestrial trophic cascades.

    Science.gov (United States)

    McCluney, Kevin E; Sabo, John L

    2016-08-17

    Despite the clear importance of water balance to the evolution of terrestrial life, much remains unknown about the effects of animal water balance on food webs. Based on recent research suggesting animal water imbalance can increase trophic interaction strengths in cages, we hypothesized that water availability could drive top-down effects in open environments, influencing the occurrence of trophic cascades. We manipulated large spider abundance and water availability in 20 × 20 m open-air plots in a streamside forest in Arizona, USA, and measured changes in cricket and small spider abundance and leaf damage. As expected, large spiders reduced both cricket abundance and herbivory under ambient, dry conditions, but not where free water was added. When water was added (free or within moist leaves), cricket abundance was unaffected by large spiders, but spiders still altered herbivory, suggesting behavioural effects. Moreover, we found threshold-type increases in herbivory at moderately low soil moisture (between 5.5% and 7% by volume), suggesting the possibility that water balance may commonly influence top-down effects. Overall, our results point towards animal water balance as an important driver of direct and indirect species interactions and food web dynamics in terrestrial ecosystems. © 2016 The Author(s).

  7. Exchanges between the shelf and the deep Black Sea: an integrated analysis of physical mechanisms

    Science.gov (United States)

    Shapiro, Georgy; Wobus, Fred; Zatsepin, Andrei; Akivis, Tatiana; Zhou, Feng

    2017-04-01

    This study provides an integrated analysis of exchanges of water, salt and heat between the north-western Black Sea shelf and the deep basin. Three contributing physical mechanisms are quantified, namely: Ekman drift, transport by mesoscale eddies at the edge of the NW Black Sea shelf and non-local cascading assisted by the rim current and mesoscale eddies. The semi-enclosed nature of the Black Sea together with its unique combination of an extensive shelf area in the North West and the deep central part make it sensitive to natural variations of fluxes, including the fluxes between the biologically productive shelf and predominantly anoxic deep sea. Exchanges between the shelf and deep sea play an important role in forming the balance of waters, nutrients and pollution within the coastal areas, and hence the level of human-induced eutrophication of coastal waters (MSFD Descriptor 5). In this study we analyse physical mechanisms and quantify shelf-deep sea exchange processes in the Black Sea sector using the NEMO ocean circulation model. The model is configured and optimized taking into account specific features of the Black Sea, and validated against in-situ and satellite observations. The study uses NEMO-BLS24 numerical model which is based on the NEMO codebase v3.2.1 with amendments introduced by the UK Met Office. The model has a horizontal resolution of 1/24×1/24° and a hybrid s-on-top-of-z vertical coordinate system with a total of 33 layers. The horizontal viscosity/diffusivity operator is rotated to reduce the contamination of vertical diffusion/viscosity by large values of their horizontal counterparts. The bathymetry is processed from ETOPO5 and capped to 1550m. Atmospheric forcing for the period 1989-2012 is given by the Drakkar Forcing Set v5.2. For comparison, the NCEP atmospheric forcing also used for 2005. The climatological runoff from 8 major rivers is included. We run the model individually for 24 calendar years without data assimilation. For

  8. The assessment of optimal MERIS ocean colour products in the shelf waters of the KwaZulu-Natal Bight, South Africa

    CSIR Research Space (South Africa)

    Smith, ME

    2013-10-01

    Full Text Available The KwaZulu-Natal Bight is a highly variable bio-optical environment, where waters over the shelf can change from the oligotrophic case 1 conditions of the Agulhas Current to the case 2 inshore environment influenced by upwelling and riverine influx...

  9. Hydrography, phytoplankton biomass and photosynthesis in shelf and oceanic waters off southeastern Brazil during autumn (may/june, 1983

    Directory of Open Access Journals (Sweden)

    Frederico Pereira Brandini

    1988-01-01

    Full Text Available Spatial distribution of chlorophyll-a, phytoplankton photosynthesis and nutrients were studied in relation to the hydrographic environment of the southeastern Brazil from May 3 to June 31 of 1983 during an oceanographia cruise conducted by the R/V "Almirante Saldanha" of the Brazilian Navy. Temperature and salinity at 5 meters depth ranged from 21 to 25º C and from 33.00 to 37.11, respectively. The concentration of nutrients varied, nitrate + nitrite-N from 1.0-3.0 µg-at/l, phosphate-P 0.1-0.9 µg-at/l and silicate-Si 5-25 µg-at/l. The chlorophyll-a concentrations along the coast varied from 0.35 to 1.48 mg/m³ with maxima in front of Paranaguá Bay (PR and over the southern shelf of Santa Catarina State. Low concentrations around 0.20 mg/m³ of uniform distribution were observed in shelf and off-shelf areas. Comparatively high concentrations were measured over the shelf break zone in front of Paranaguá Bay indicationg the occurrence of shelf break upwelling of deep nutrient rich waters. The pattern of vertical distribution was stratified and irregular in coastal stations and uniform in shelf and oceanic waters although some subsurface peaks were sometimes detected. The integrated chlorophyll values within the euphotic layer varied between 2.70 and 28.06 mg/m². The surface photo synthetic capacity varied from 0.4 to 7.7 mgC/mgChl.a/hr with higher values obtained in coastal areas.. The vertical distributions were variable in coastal areas and more uniform in mid-shelf stations. Sub-surface maxima of photosynthesis were detected in both nearshore and off-shore stations, and surface inhibition was not observed.Os padrões de distribuição espacial de parâmetros hidrográficos, clorofila-a e fotossíntese do fitoplancton são estudados em relação ao regime oceanográfico da região sueste do Brasil nos meses de maio e junho de 1983. A região oceânica foi totalmente dominada pela Agua Tropical da Corrente do Brasil (AT com caracter

  10. A cascade of warming impacts brings bluefin tuna to Greenland waters

    DEFF Research Database (Denmark)

    MacKenzie, Brian; Payne, Mark; Boje, Jesper

    Rising ocean temperatures are causing marine fish species to shift spatial distributions and ranges, and are altering predator-prey dynamics in food-webs. Most documented cases of species shifts so far involve relatively small species at lower trophic levels, and consider individual species...... since 1985, when temperatures began to rise. The presence of bluefin tuna in this region is likely due to a combination of warm temperatures that are physiologically more tolerable and immigration of an important prey species into the region. We conclude that a cascade of climate change impacts...

  11. Effect of water and gluten on physico-chemical properties and stability of ready to eat shelf-stable pasta.

    Science.gov (United States)

    Diantom, Agoura; Carini, Eleonora; Curti, Elena; Cassotta, Fabrizio; D'Alessandro, Alessandro; Vittadini, Elena

    2016-03-15

    A multi-analytical and multi-dimensional approach was used to investigate the effect of moisture and gluten on physico-chemical properties of shelf-stable ready to eat (RTE) pasta. Moisture and frozen water contents were not affected by formulation nor storage time. Hardness and retrograded amylopectin significantly increased during storage in all samples, more markedly in pasta with the lowest moisture content. Higher amounts of water and gluten reduced pasta hardening and contributed to control RTE pasta quality. (1)H FID became steeper in all samples during storage, but no effect of high moisture and gluten levels was observed on the mobility of these protons. Three proton T2 populations were observed (population C, population D and population E). Population C and D were not resolved during all storage. (1)H T2 relaxation time of the most abundant population (population E) shifted to shorter times and the amount of protons increased during storage, more importantly in the samples with lower moisture and gluten content. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Bacterial biomass and heterotrophic potential in the waters of the Chesapeake Bay plume and contiguous continental shelf

    Science.gov (United States)

    Kator, H. I.; Zubkoff, P. L.

    1981-01-01

    Seasonal baseline data on bacterial biomass and heterotrophic uptake in the Chesapeake Bay plume and contiguous Atlantic Ocean shelf waters are discussed. Viable count bacterial numbers in surface water samples collected during June 1980 ranged from a maximum of 190,000 MPN (most probable number)/ml at the Bay mouth to a minimum of 7900 MPN/ml offshore. Similarly, direct count densities ranged from 1,800,000 BU (bacterial units)/ml to 24,000 BU/ml. Heterotrophic potential (V max) was largest at the Bay mouth and lowest offshore. Biomass and V max values usually decreased with depth although subsurface maxima were occasionally observed at inshore stations. Correlation of biomass and heterotrophic potential data with selected hydrographic variables was determind with a nonparametric statistic. Results indicate viable counts are positively and significantly correlated with total chlorophyll, temperature, direct count and V max during June 1980; significant negative correlations are obtained with salinity and depth. Calculations of bacterial standing crop are discussed.

  13. Performance and Health Risk Assessment of Commercial Off-the-Shelf Individual Water Purifiers

    National Research Council Canada - National Science Library

    Bettin, William; Lundquist, Arthur; Clarke, Steven; Richards, Steven

    2006-01-01

    .... This project had three discrete objectives: (1) Develop a military-use specific protocol for testing the efficiency and functionality of IWPs in producing microbiologically safe drinking water; (2...

  14. Front-Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross-Shelf Exchange of Diatom Taxa in the Shelf-Slope Area off Concepción (˜36-37°S)

    Science.gov (United States)

    Morales, Carmen E.; Anabalón, Valeria; Bento, Joaquim P.; Hormazabal, Samuel; Cornejo, Marcela; Correa-Ramírez, Marco A.; Silva, Nelson

    2017-11-01

    In eastern boundary current systems (EBCSs), submesoscale to mesocale variability contributes to cross-shore exchanges of water properties, nutrients, and plankton. Data from a short-term summer survey and satellite time series (January-February 2014) were used to characterize submesoscale variability in oceanographic conditions and phytoplankton distribution across the coastal upwelling and coastal transition zones north of Punta Lavapié, and to explore cross-shelf exchanges of diatom taxa. A thermohaline front (FRN-1) flanked by a mesoscale anticyclonic intrathermocline eddy (ITE-1), or mode-water eddy, persisted during the time series and the survey was undertaken during a wind relaxation event. At the survey time, ITE-1 contributed to an onshore intrusion of warm oceanic waters (southern section) and an offshore advection of cold coastal waters (northern section), with the latter forming a cold, high chlorophyll-a filament. In situ phytoplankton and diatom biomasses were highest at the surface in FRN-1 and at the subsurface in ITE-1, whereas values in the coastal zone were lower and dominated by smaller cells. Diatom species typical of the coastal zone and species dominant in oceanic waters were both found in the FRN-1 and ITE-1 interaction area, suggesting that this mixture was the result of both offshore and onshore advection. Overall, front-eddy interactions in EBCSs could enhance cross-shelf exchanges of coastal and oceanic plankton, as well as sustain phytoplankton growth in the slope area through localized upward injections of nutrients in the frontal zone, combined with ITE-induced advection and vertical nutrient inputs to the surface layer.

  15. Particulate organic matter in shelf waters of Prinsesse Asrid Kyst, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.; Bhosle, N.B.

    In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l-1 and from 0.28 to 5.24 mg l-1 and particulate phosphorus (PP) varied from 0.71 to 5.18 mu g l-1 and from 0.78 to 20.34 mu g l-1, respectively...

  16. Leucine, starch and bicarbonate utilization by specific bacterial groups in surface shelf waters off Galicia (NW Spain).

    Science.gov (United States)

    Teira, E; Hernando-Morales, V; Guerrero-Feijóo, E; Varela, M M

    2017-06-01

    The capability of different bacterial populations to degrade abundant polymers, such as algal-derived polysaccharides, or to utilize preferentially polymers over monomers, remains largely unknown. In this study, microautoradiography was combined with fluorescence in situ hybridization (MAR-FISH) to evaluate the ability of Bacteroidetes, SAR11, Roseobacter spp., Gammaproteobacteria and SAR86 cells to use bicarbonate, leucine and starch under natural light conditions at two locations in shelf surface waters off NW Spain. The percentage of cells incorporating bicarbonate was relatively high (mean 32% ± 4%) and was positively correlated with the intensity of solar radiation. The proportion of cells using starch (mean 56% ± 4%) or leucine (mean 47% ± 4%) was significantly higher than that using bicarbonate. On average, SAR11, Roseobacter spp. and Gammaproteobacteria showed a similarly high percentage of cells using leucine (47%-65% of hybridized cells) than using starch (51%-64% of hybridized cells), while Bacteroidetes and SAR86 cells preferentially used starch (53% of hybridized cells) over leucine (34%-40% of hybridized cells). We suggest that the great percentage of bacteria using starch is related to a high ambient availability of polymers associated to algal cell lysis, which, in turn, weakens the short-term coupling between phytoplankton release and bacterial production. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

    Directory of Open Access Journals (Sweden)

    L. M. Wehrmann

    2009-04-01

    Full Text Available Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC production, combined with sulfate reduction rates not exceeding 3 nmol S cm−3 d−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH2O groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23–18 GC indicated diagenetic carbonate precipitation. This was

  18. Physical (Hydrography), chemical (CTD), and biological (Water Quality) processes of the Texas-Louisiana continental shelf, 2013 (NCEI Accession 0162440)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Two sets of CTD data were taken during the 2013 Shelfwide Hypoxia cruise off the Louisiana continental shelf. Hydrographic data were obtained with the LUMCON SeaBird...

  19. Water limitations on forest carbon cycling and conifer traits along a steep climatic gradient in the Cascade Mountains, Oregon

    Science.gov (United States)

    Berner, L. T.; Law, B. E.

    2015-11-01

    Severe droughts occurred in the western United States during recent decades, and continued human greenhouse gas emissions are expected to exacerbate warming and drying in this region. We investigated the role of water availability in shaping forest carbon cycling and morphological traits in the eastern Cascade Mountains, Oregon, focusing on the transition from low-elevation, dry western juniper (Juniperus occidentalis) woodlands to higher-elevation, wetter ponderosa pine (Pinus ponderosa) and grand fir (Abies grandis) forests. We examined 12 sites in mature forests that spanned a 1300 mm yr-1 gradient in mean growing-year climate moisture index (CMIgy ), computed annually (1964 to 2013) as monthly precipitation minus reference evapotranspiration and summed October to September. Maximum leaf area, annual aboveground productivity, and aboveground live tree biomass increased with CMIgy (r2 = 0.67-0.88, P gy (r2 = 0.53, P gy and extensive insect outbreak. Traits of stress-tolerant juniper included short stature, high wood density for cavitation resistance, and high investment in water transport relative to leaf area. Species occupying wetter areas invested more resources in height growth in response to competition for light relative to investment in hydraulic architecture. Consequently, maximum tree height, leaf area : sapwood area ratio, and stem wood density were all correlated with CMIgy . The tight coupling of forest carbon cycling and species traits with water availability suggests that warmer and drier conditions projected for the 21st century could have significant biogeochemical, ecological, and social consequences in the Pacific Northwest.

  20. Parameterization of light scattering for solving the inverse problem of determining the concentrations of the principal light scattering and absorbing admixtures in shelf waters

    Directory of Open Access Journals (Sweden)

    Vadim N. Pelevin

    2001-12-01

    Full Text Available A method for estimating the water backscattering coefficient was put forward on the basis of experimental data of diffuse attenuation coefficient for downwelling irradiance and irradiance reflectance. Calculations were carried out for open sea waters of different types and the spectral dependencies were found ("anomalous" spectra and explained. On this basis, a new model of light backscattering on particles in the sea is proposed. This model may be useful for modelling remote sensing reflectance spectra in order to solve the inverse problems of estimating the concentration of natural admixtures in shelf waters.

  1. The assemblage composition and structure of swimming crabs (Portunoidea) in continental shelf waters of southeastern Brazil

    Science.gov (United States)

    Andrade, L. S.; Frameschi, I. F.; Costa, R. C.; Castilho, A. L.; Fransozo, A.

    2015-02-01

    Three regions along the Brazilian coast characterized by the occurrence of contrasting natural phenomena, such as upwellings and continental input, were surveyed to determine the composition and structure of the assemblage of swimming crabs. Twelve monthly collections were undertaken (July 2010 to June 2011) in Macaé, Rio de Janeiro (MAC); Ubatuba, São Paulo (UBA); and São Francisco do Sul, Santa Catarina (SFS). The lowest values ​​of the phi sediment grain size measure, bottom temperature and the highest values of organic matter and salinity were measured in MAC. In all, 10,686 individuals were collected, belonging to six species of Portunoidea: Arenaeus cribrarius, Callinectes danae, Callinectes ornatus, Callinectes sapidus, Achelous spinicarpus and Achelous spinimanus. A Multiple Response Permutation Procedure (MRPP) test indicated that the species composition differed significantly among the sampling sites, showing substantial heterogeneity in the composition and abundance of species among regions. The results suggest that C. danae was more abundant in waters with lower salinity and lower organic matter content. In contrast, A. spinimanus is positively correlated with these factors, showing a greater abundance under the opposite conditions. Callinectes ornatus appeared not to show strong selectivity for particular habitat characteristics. We conclude from these findings that areas affected by different phenomena produce changes in the composition and abundance of the assemblage of Portunoidea. Although the strength of eutrophication differs between UBA and MAC, the substantial continental inflow affecting SFS favors the development of species that complete their life cycle in the estuary.

  2. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Integration with Models of Other Water Recovery Subsystems

    Science.gov (United States)

    Perry, Bruce; Anderson, Molly

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station (ISS) Water Processor Assembly (WPA) to form a complete Water Recovery System (WRS) for future missions. Independent chemical process simulations with varying levels of detail have previously been developed using Aspen Custom Modeler (ACM) to aid in the analysis of the CDS and several WPA components. The existing CDS simulation could not model behavior during thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. The first part of this paper describes modifications to the ACM model of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version of the model can accurately predict behavior during thermal startup for both NaCl solution and pretreated urine feeds. The model is used to predict how changing operating parameters and design features of the CDS affects its performance, and conclusions from these predictions are discussed. The second part of this paper describes the integration of the modified CDS model and the existing WPA component models into a single WRS model. The integrated model is used to demonstrate the effects that changes to one component can have on the dynamic behavior of the system as a whole.

  3. Dynamics of microalgal communities in the water-column/sediment interface of the inner shelf off Parana State, Southern Brazil

    Directory of Open Access Journals (Sweden)

    Ricardo Luiz Queiroz

    2004-12-01

    Full Text Available The composition and biomass of the microalgal community at the water-column/sediment interface on the continental shelf off Parana State (Brazil were studied every 2 months during 1999. Samples for cell identification and determination of chlorophyll a were taken from the interface layer and at discrete depths up to 4 m above the sediment. Results showed a community mainly formed by benthic and planktonic diatoms >30 µm, benthic diatoms 30 µm, which accounted for most of the pigment biomass, were resuspended from the interface after turbulent periods, and may take advantage of calm periods to stay and grow at the interface. Small benthic diatoms were more susceptible to wind-induced turbulence occurring in higher densities in the water column just above the water-sediment interface. A cyanobacterial bloom (Trichodesmiun was observed at these bottom layers in the spring-summer periods.A composição geral e a biomassa da comunidade microalgal da interface sedimento/água da plataforma do Estado do Paraná (Brasil foram estudadas em 1999 em relação ao regime de ventos. A cada dois meses foram coletadas amostras para a identificação de organismos e determinação de clorofila a, na interface água-sedimento e em profundidades discretas, ao longo da coluna d'água, até 4m acima do sedimento. Os resultados obtidos revelaram uma comunidade constituída principalmente por diatomáceas planctônicas e bentônicas maiores que 30 µm, diatomáceas bentônicas menores que 30 µm, e cianobactérias coloniais. As densidades celulares foram geralmente mais altas na interface. Eventos de mistura e sedimentação parecem ser determinantes na regulação da composição e biomassa de tais comunidades. Formas menores, mais susceptíveis à turbulência, dominaram a comunidade de água de fundo na maioria das ocasiões, e foram as mais abundantes na interface apenas em períodos de extrema estabilidade. Células maiores, aparentemente contendo a maior parte

  4. Temporal and vertical variability in optical properties of New England shelf waters during late summer and spring

    Science.gov (United States)

    Sosik, Heidi M.; Green, Rebecca E.; Pegau, W. Scott; Roesler, Collin S.

    2001-05-01

    Relationships between optical and physical properties were examined on the basis of intensive sampling at a site on the New England continental shelf during late summer 1996 and spring 1997. During both seasons, particles were found to be the primary source of temporal and vertical variability in optical properties since light absorption by dissolved material, though significant in magnitude, was relatively constant. Within the particle pool, changes in phytoplankton were responsible for much of the observed optical variability. Physical processes associated with characteristic seasonal patterns in stratification and mixing contributed to optical variability mostly through effects on phytoplankton. An exception to this generalization occurred during summer as the passage of a hurricane led to a breakdown in stratification and substantial resuspension of nonphytoplankton particulate material. Prior to the hurricane, conditions in summer were highly stratified with subsurface maxima in absorption and scattering coefficients. In spring, stratification was much weaker but increased over the sampling period, and a modest phytoplankton bloom caused surface layer maxima in absorption and scattering coefficients. These seasonal differences in the vertical distribution of inherent optical properties were evident in surface reflectance spectra, which were elevated and shifted toward blue wavelengths in the summer. Some seasonal differences in optical properties, including reflectance spectra, suggest that a significant shift toward a smaller particle size distribution occurred in summer. Shorter timescale optical variability was consistent with a variety of influences including episodic events such as the hurricane, physical processes associated with shelfbreak frontal dynamics, biological processes such as phytoplankton growth, and horizontal patchiness combined with water mass advection.

  5. Refrigerated Shelf Life of a Coconut Water-Oatmeal Mix and the Viability of Lactobacillus Plantarum Lp 115-400B.

    Science.gov (United States)

    Dharmasena, Muthu; Barron, Felix; Fraser, Angela; Jiang, Xiuping

    2015-08-10

    Non-dairy probiotic products have the advantage of being lactose-free and can be manufactured to sustain the growth of probiotics. In this study, coconut water and oatmeal were used with the probiotic, Lactobacillus plantarum Lp 115-400B ( L. plantarum ) as a starter culture. Two separate treatments were carried out probiotic (P) and probiotic and prebiotic (PP) added. In both treatments, oatmeal-coconut water matrix was inoculated with 7 log CFU/g of L. plantarum and fermented at 27 °C for 10 h. For the PP treatment, 1 g of inulin/100 mL of the product was added additionally. The fermented products were then refrigerated (4 °C) and the viability of L. plantarum , pH, total acidity, and apparent viscosity of the matrix were monitored at selected time intervals. The shelf life to reach was defined by maintenance of L. plantarum count of 7 log CFU/g product. Refrigerated shelf life was determined to be seven-weeks for the P treatment and five-weeks for PP treatment. A significant reduction of pH was observed at the end of the considered shelf life; conversely, the apparent viscosity of the product did not change significantly.

  6. Refrigerated Shelf Life of a Coconut Water-Oatmeal Mix and the Viability of Lactobacillus Plantarum Lp 115-400B

    Directory of Open Access Journals (Sweden)

    Muthu Dharmasena

    2015-08-01

    Full Text Available Non-dairy probiotic products have the advantage of being lactose-free and can be manufactured to sustain the growth of probiotics. In this study, coconut water and oatmeal were used with the probiotic, Lactobacillus plantarum Lp 115-400B (L. plantarum as a starter culture. Two separate treatments were carried out probiotic (P and probiotic and prebiotic (PP added. In both treatments, oatmeal-coconut water matrix was inoculated with 7 log CFU/g of L. plantarum and fermented at 27 °C for 10 h. For the PP treatment, 1 g of inulin/100 mL of the product was added additionally. The fermented products were then refrigerated (4 °C and the viability of L. plantarum, pH, total acidity, and apparent viscosity of the matrix were monitored at selected time intervals. The shelf life to reach was defined by maintenance of L. plantarum count of 7 log CFU/g product. Refrigerated shelf life was determined to be seven-weeks for the P treatment and five-weeks for PP treatment. A significant reduction of pH was observed at the end of the considered shelf life; conversely, the apparent viscosity of the product did not change significantly.

  7. EFFECT OF TROUT PRODUCTION IN CONCRETE PONDS WITH A CASCADING FLOW OF WATER ON PHYSICAL AND CHEMICAL PROPERTY OF WATER

    Directory of Open Access Journals (Sweden)

    Marcin Sidoruk

    2014-10-01

    Full Text Available Fish rearing causes changes in water quality due to the use of feed, mineral and organic fertilizers, pharmaceuticals and disinfectants. Rational fishery management aims to maintain or restore the quality of water in natural ecosystems. Cultures produce a certain amount of waste and pollutants released into the environment with waters departing from ponds, but their harmfulness depends on the conditions and type of farming. Studies on the assessment of the effects of rearing trout on physical and chemical properties of surface water were carried out in 2010-2012. Were chosen trout farm located in the Pomeranian province about 36 miles southeast of Słupsk. Water samples for physical and chemical analysis were collected every two months (a total of 12 sets samples collected and labeled them: temperature [°C], dissolved oxygen [mg · dm-3], oxygen saturation [%] electrolytic conductivity [S · cm-1], pH, redox potential [mV] and BOD5 and CODCr. The study showed that the water used to supply breeding facilities meet the requirements to be met which are inland water salmonid habitat. Only periodically for BOD5 standards have been slightly exceeded. After passing through the joints deterioration of water quality did not cause a change in the quality of the class, if only temporarily BOD5 ratio were lower in its quality from the first to the third class.

  8. A cascade of warming impacts brings bluefin tuna to Greenland waters

    DEFF Research Database (Denmark)

    MacKenzie, Brian R.; Payne, Mark R.; Boje, Jesper

    2014-01-01

    Rising ocean temperatures are causing marine fish species to shift spatial distributions and ranges, and are altering predator-prey dynamics in food webs. Most documented cases of species shifts so far involve relatively small species at lower trophic levels, and consider individual species in ec...... impacts is restructuring the food web in east Greenland waters.......Rising ocean temperatures are causing marine fish species to shift spatial distributions and ranges, and are altering predator-prey dynamics in food webs. Most documented cases of species shifts so far involve relatively small species at lower trophic levels, and consider individual species...

  9. Arctic Ocean outflow and glacier-ocean interactions modify water over the Wandel Sea shelf (northeastern Greenland)

    DEFF Research Database (Denmark)

    Dmitrenko, Igor A.; Kirillov, Sergey A.; Rudels, Bert

    2017-01-01

    The first-ever conductivity-temperature-depth (CTD) observations on the Wandel Sea shelf in northeastern Greenland were collected in April-May 2015. They were complemented by CTDs taken along the continental slope during the Norwegian FRAM 2014-2015 drift. The CTD profiles are used to reveal...

  10. Physical (Hydrography), chemical (CTD), and biological (Water Quality) processes of the Texas-Louisiana continental shelf, 2012 (NCEI Accession 0162101)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Two sets of CTD data were taken during the 2012 surveys of the Louisiana continental shelf—Transect C off Terrebonne Bay and Transect F off Atchafalaya Bay and the...

  11. Efficacy evaluation of a new water sanitizer for increasing the shelf life of Southern Australian King George Whiting and Tasmanian Atlantic Salmon fillets.

    Science.gov (United States)

    Khazandi, Manouchehr; Deo, Permal; Ferro, Sergio; Venter, Henrietta; Pi, Hongfei; Crabb, Simon; Amorico, Tony; Ogunniyi, Abiodun D; Trott, Darren J

    2017-12-01

    The bacterial species and specific spoilage organisms associated with the Southern Australian King George Whiting (KGW) and Tasmanian Atlantic Salmon (TAS), and the efficacy of a HOCl-containing water-based sanitization product (Electro-Chemically Activated Solution, by ECAS4) in extending the shelf life of KGW and TAS fillets were evaluated. Fillets were washed with an ECAS4 solution containing either 45 ppm or 150 ppm of free chlorine and bacterial species enumerated on selective and non-selective media, followed by identification of pure isolates by 16 S rRNA gene sequencing. The dominant spoilage microbiota in KGW and TAS fillets stored at 4 ± 1 °C were Pseudomonas spp. and Shewanella spp. At either concentration, ECAS4 significantly reduced total bacterial load and specific spoilage organisms on KGW and TAS fillets (approx. 1-2 log colony-forming units) during storage and significantly extended the shelf life of the fillets by 2 and 4 days, respectively. The significant increase in shelf life and quality of fillets was corroborated by raw and cooked sensory evaluation. ECAS4 sanitization could have a significant impact on the overall food industry, translating into health and economic benefits through reduction of food spoilage bacteria and potentially, foodborne pathogens without many of the disadvantages of currently approved biocides. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Diagenesis and reservoir quality evolution of palaeocene deep-water, marine sandstones, the Shetland-Faroes Basin, British continental shelf

    Energy Technology Data Exchange (ETDEWEB)

    Mansurbeg, H. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Morad, S. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Department of Petroleum Geosciences, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Salem, A. [Faculty of Education at Kafr El-Sheikh, Tanta University, Kafr El-Sheikh (Egypt); Marfil, R.; Caja, M.A. [Departmento Petrologia y Geoquimica, Facultad de Geologia, UCM, 28040 Madrid (Spain); El-ghali, M.A.K. (Geology Department, Al-Fateh University, P.O. Box 13696, Libya); Nystuen, J.P. [Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, NO-0316 Oslo (Norway); Amorosi, A. [Department of Earth Sciences, University of Bologna, Via Zamboni 67, 40127 Bologna (Italy); Garcia, D. [Centre SPIN, Department GENERIC, Ecole Nationale Superieure des Mines de Saint Etienne 158, Cours Fauriel 42023, Saint-Etienne (France); La Iglesia, A. [Instituto de Geologia Economica (CSIC-UCM), Facultad de Geologia, UCM, 28040 Madrid (Spain)

    2008-06-15

    The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-10.9 permille and -3.8 permille), trace amounts of non-ferroan dolomite, siderite ({delta}{sup 18}O{sub V-PDB}=-14.4 permille to -0.6 permille), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-12.9 permille to -7.8 permille) and Fe-dolomite/ankerite ({delta}{sup 18}O{sub V-PDB}=-12.1 permille to -6.3 permille) at temperatures of 50-140 and 60-140 C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive

  13. Algorithm Development and Validation of CDOM Properties for Estuarine and Continental Shelf Waters Along the Northeastern U.S. Coast

    Science.gov (United States)

    Mannino, Antonio; Novak, Michael G.; Hooker, Stanford B.; Hyde, Kimberly; Aurin, Dick

    2014-01-01

    An extensive set of field measurements have been collected throughout the continental margin of the northeastern U.S. from 2004 to 2011 to develop and validate ocean color satellite algorithms for the retrieval of the absorption coefficient of chromophoric dissolved organic matter (aCDOM) and CDOM spectral slopes for the 275:295 nm and 300:600 nm spectral range (S275:295 and S300:600). Remote sensing reflectance (Rrs) measurements computed from in-water radiometry profiles along with aCDOM() data are applied to develop several types of algorithms for the SeaWiFS and MODIS-Aqua ocean color satellite sensors, which involve least squares linear regression of aCDOM() with (1) Rrs band ratios, (2) quasi-analytical algorithm-based (QAA based) products of total absorption coefficients, (3) multiple Rrs bands within a multiple linear regression (MLR) analysis, and (4) diffuse attenuation coefficient (Kd). The relative error (mean absolute percent difference; MAPD) for the MLR retrievals of aCDOM(275), aCDOM(355), aCDOM(380), aCDOM(412) and aCDOM(443) for our study region range from 20.4-23.9 for MODIS-Aqua and 27.3-30 for SeaWiFS. Because of the narrower range of CDOM spectral slope values, the MAPD for the MLR S275:295 and QAA-based S300:600 algorithms are much lower ranging from 9.9 and 8.3 for SeaWiFS, respectively, and 8.7 and 6.3 for MODIS, respectively. Seasonal and spatial MODIS-Aqua and SeaWiFS distributions of aCDOM, S275:295 and S300:600 processed with these algorithms are consistent with field measurements and the processes that impact CDOM levels along the continental shelf of the northeastern U.S. Several satellite data processing factors correlate with higher uncertainty in satellite retrievals of aCDOM, S275:295 and S300:600 within the coastal ocean, including solar zenith angle, sensor viewing angle, and atmospheric products applied for atmospheric corrections. Algorithms that include ultraviolet Rrs bands provide a better fit to field measurements than

  14. A Cascade Disaster Caused by Geological and Coupled Hydro-Mechanical Factors—Water Inrush Mechanism from Karst Collapse Column under Confining Pressure

    Directory of Open Access Journals (Sweden)

    Hao Li

    2017-11-01

    Full Text Available The water inrush from karst collapse column (KCC is a cascading, vicious cycle disaster caused by geological and mining activities, that can cause serious casualties and property losses. The key to preventing this risk is to study the mechanism of water inrush under confining pressure. Aiming at the investigationg the characteristics of the KCC named X1 in Chensilou mine, a series of methods, including connectivity experiments, water pressure monitoring tests in two side-walls, and numerical simulations based on plastic damage-seepage (PD-S theory have been developed. The methods are used to test the security of the 2519 mining area, the damage thickness, pore water pressure, and seepage vector in the X1. The results indicate that the X1 has a certain water blocking capacity. In addition, with the decrease of confining pressure and increase of shear stress, deviatoric stress could cause the increase of permeability, the reduction of strength, and the reduction of pore water pressure in KCC. Therefore the increased effective stress in the rock will force the rock to become more fractured. Conversely, the broken rock could cause the change of stress, and further initiate new plastic strains, damage and pore water pressure until a new equilibrium is reached. This cascading water inrush mechanism will contribute to the exploitation of deep coal resources in complex geological and hydrogeological conditions.

  15. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  16. Habitat characteristics of the shelf distribution of the harbour porpoise (Phocoena phocoena in the waters around the Faroe Islands during summer

    Directory of Open Access Journals (Sweden)

    Henrik Skov

    2003-07-01

    Full Text Available Observations from a large number of seabird line-transect surveys conducted in Faroese waters are used to derive some general conclusions regarding the distribution of harbour porpoises (Phocoena phocoena in the region using estimates of encounter rates (no./km-1 in different meso-scale habitats around the Faroes during the breeding season (May-September. Based on a sub-set of the data collected during calm conditions (sea states below Beaufort 3 we analysed the distribution of harbour porpoises in relation to 5 potentially important physical parameters: water depth, distance to shore, slope of the ocean floor, distance to tidal front and Beaufort sea state. These parameters were determined from data collected during the surveys, the literature as well as from the new bathymetry established for the Faroese shelf. In order to link the differently scaled physical parameters with the encounter rates and sea states recorded during the surveys we used a suite of geo-statistical and raster-based GIS techniques based on a uniform grid resolution of 1 km in UTM zone 29 N projection. After removing parameters with insignificant effects a model of main effects was produced with sea state and distance to the tidal front having a significant negative effect on the rate of encountering harbour porpoises during both sets of cruises analysed (August 1997 and other surveys. During both sets of cruises the distance to the tidal front had a larger effect on the distribution of the animals than sea state. The strong relationship between harbour porpoise distribution and the average position of the tidal front around the Faroes strongly suggests that the species concentrates near the quasi-stationary circular shelf front separating mixed from stratified waters around the Faroes. However, the importance of shelf fronts for the distribution of harbour porpoises needs to be studied in detail in order to establish the proportionof the populations associated with these

  17. 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.

  18. Transport of plutonium in surface and sub-surface waters from the Arctic shelf to the North Pole via the Lomonosov Ridge

    International Nuclear Information System (INIS)

    Leon Vintro, L.; McMahon, C.A.; Mitchell, P.I.; Josefsson, D.; Holm, E.; Roos, P.

    2002-01-01

    New data on the levels and long-range transport of plutonium in the Arctic Ocean, recorded in the course of two expeditions to this zone in 1994 and 1996, are discussed in this paper. Specifically, approximately 100 plutonium measurements in surface and sub-surface water sampled at 58 separate stations throughout the Kara, Laptev and East Siberian Seas, as well as along latitudinal transects across the Lomonosov Ridge, are reported and interpreted in terms of the circulation pathways responsible for the transport of this element from the North Atlantic to the Arctic Shelf and into the Arctic interior. In addition, the behaviour of plutonium in its transit through the vast Arctic shelf seas to open waters under extreme environmental conditions is discussed in terms of the partitioning of plutonium between filtered (<0.45 μm) seawater and suspended particulate, and its association with colloidal matter. Finally, limited evidence of the presence of a colloidal plutonium component in Arctic waters subject to direct riverine input is adduced

  19. Summertime calcium carbonate undersaturation in shelf waters of the western Arctic Ocean – how biological processes exacerbate the impact of ocean acidification

    Directory of Open Access Journals (Sweden)

    N. R. Bates

    2013-08-01

    Full Text Available The Arctic Ocean accounts for only 4% of the global ocean area, but it contributes significantly to the global carbon cycle. Recent observations of seawater CO2-carbonate chemistry in shelf waters of the western Arctic Ocean, primarily in the Chukchi Sea, from 2009 to 2011 indicate that bottom waters are seasonally undersaturated with respect to calcium carbonate (CaCO3 minerals, particularly aragonite. Nearly 40% of sampled bottom waters on the shelf have saturation states less than one for aragonite (i.e., Ωaragonite 3-secreting organisms, while 80% of bottom waters present had Ωaragonite values less than 1.5. Our observations indicate seasonal reduction of saturation states (Ω for calcite (Ωcalcite and aragonite (Ωaragonite in the subsurface in the western Arctic by as much as 0.8 and 0.5, respectively. Such data indicate that bottom waters of the western Arctic shelves were already potentially corrosive for biogenic and sedimentary CaCO3 for several months each year. Seasonal changes in Ω are imparted by a variety of factors such as phytoplankton photosynthesis, respiration/remineralization of organic matter and air–sea gas exchange of CO2. Combined, these processes either increase or enhance in surface and subsurface waters, respectively. These seasonal physical and biological processes also act to mitigate or enhance the impact of Anthropocene ocean acidification (OA on Ω in surface and subsurface waters, respectively. Future monitoring of the western Arctic shelves is warranted to assess the present and future impact of ocean acidification and seasonal physico-biogeochemical processes on Ω values and Arctic marine ecosystems.

  20. Recent trends in the abundance of plaice Pleuronectes platessa and cod Gadus morhua in shallow coastal waters of the Northeastern Atlantic continental shelf – a review

    DEFF Research Database (Denmark)

    Dutz, Jörg; Støttrup, Josianne Gatt; Stenberg, Claus

    2016-01-01

    of the southern distribution boundary in the Bay of Biscay and deepening of stocks in the North Sea. In contrast, no trend in shallow water abundance of plaice similar to a decline in deep-water stocks during the 1970s and their slow recovery during the 2000s is apparent in the Skagerrak/Kattegat. Although......Shallow, near-shore water habitats on the continental shelf of the Northeast Atlantic have been productive fishing areas in the past. Here, we review the present knowledge about (i) recent trends in the abundance of plaice and cod in these habitats and (ii) hypotheses regarding the factors...... responsible for any trends. At present, only a few studies exist on the trends of abundance of plaice or cod, namely from the Bay of Biscay, the North Sea and the Skagerrak/Kattegat. They suggest a declining abundance in coastal, shallow areas and – at least for plaice – a latitudinal gradient with an erosion...

  1. Combined effects of thermosonication and slightly acidic electrolyzed water on the microbial quality and shelf life extension of fresh-cut kale during refrigeration storage.

    Science.gov (United States)

    Mansur, Ahmad Rois; Oh, Deog-Hwan

    2015-10-01

    This study evaluated the efficacy of thermosonication combined with slightly acidic electrolyzed water (SAcEW) on the shelf life extension of fresh-cut kale during storage at 4 and 7 °C. Each kale (10 ± 0.2 g) was inoculated to contain approximately 6 log CFU/g of Listeria monocytogenes. Each inoculated or uninoculated samples was dip treated at 40 °C for 3 min with deionized water, thermosonication (400 W/L), SAcEW (5 mg/L), sodium chlorite (SC; 100 mg/L), sodium hypochlorite (SH; 100 mg/L), and thermosonication combined with SAcEW, SC, and SH (TS + SAcEW, TS + SC, and TS + SH, respectively). Growths of L. monocytogenes and spoilage microorganisms and changes in sensory (overall visual quality, browning, and off-odour) were evaluated. The results show that lag time and specific growth rate of each microorganism were not significantly (P > 0.05) affected by treatment and storage temperature. Exceeding the unacceptable counts of spoilage microorganisms did not always result in adverse effects on sensory attributes. This study suggests that TS + SAcEW was the most effective method to prolong the shelf life of kale with an extension of around 4 and 6 days at 4 and 7 °C, respectively, and seems to be a promising method for the shelf life extension of fresh produce. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Sonograph patterns of the central western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.

    knolls. A transition zone with tonal variations is present between 40 and 60 m water depth. Ground-truth data sediment and rock distribution maps indicate depositional (inner shelf), nondepositional or erosional (outer shelf) environments and a...

  3. Vulnerability of water supply from the Oregon Cascades to changing climate: linking science to users and policy

    Science.gov (United States)

    Kathleen A. Farley; Christina Tague; Gordon E. Grant

    2011-01-01

    Despite improvements in understanding biophysical response to climate change, a better understanding of how such changes will affect societies is still needed. We evaluated effects of climate change on the coupled human-environmental system of the McKenzie River watershed in the Oregon Cascades in order to assess its vulnerability. Published empirical and modeling...

  4. Synchronous response of sedimentary organic carbon accumulation on the inner shelf of the East China Sea to the water impoundment of Three Gorges and Gezhouba Dams

    Science.gov (United States)

    Lin, Jia; Zhu, Qing; Hong, Yuehui; Yuan, Lirong; Liu, Jinzhong; Xu, Xiaoming; Wang, Jianghai

    2018-01-01

    Coastal seas, located between continents and the open ocean, are an important active carbon pool. The sedimentary total organic carbon (TOC) in these areas is a mixture of terrestrial and marine sources, and can be a powerful proxy for tracing natural processes and human activities. In this study, one fine-grained sediment core (DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon (BC) contents and TOC stable carbon isotope ratios (δ13C). By combining these data with 210Pb dating, an improved carbon correction model and a two end-member mixing model, we reconstructed century-scale high-resolution sequences of corrected TOC, terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record. The two events, shown as two minima in the TOC profiles, correspond temporally to 1985-1987 AD and 2003-2006 AD, which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam, respectively. In addition, the variations in TOC contents and δ13C values before, during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River. The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological effects on the inner shelf of the East China Sea to the water impoundment of the dams. These new TOC records reflect the interaction between natural and anthropogenic processes and, accordingly, provide a deep insight and important references for assessing marine ecological effects resulting from water impoundment of largescale dams.

  5. Climatology of the oceanography in the northern South China Sea Shelf-sea (NoSoCS) and adjacent waters: Observations from satellite remote sensing

    Science.gov (United States)

    Pan, X.; Wong, G. T.; Tai, J.; Ho, T.

    2013-12-01

    By using the observations from multiple satellite sensors, the climatology of the oceanography, including the surface wind vector, sea surface temperature (SST), surface chlorophyll a concentration (Chl_a), and vertically integrated net primary production (PPeu), in the northern South China Sea Shelf-sea (NoSoCS) and adjacent waters is evaluated. Regional and sub-regional mechanisms in driving the coastal processes, which influence the spatial and temporal distributional patterns in water component, are assessed. Seasonal vertical convective mixing by wind and surface heating/cooling is the primary force in driving the annual changes in SST and Chl_a in the open South China Sea (SCS), in which highly negative correlation coefficients between Chl_a and SST and moderately positive correlation coefficients between Chl_a and wind speed are found. Together, the seasonal variations in SST and wind speed account for about 80% of the seasonal variation in Chl_a. In the NoSoCS as a whole, however, the contribution is reduced to about 40%, primarily due to the effect of the Pearl River plume. A tongue of water extending eastward from the mouth of the River into the middle shelf with positive correlation coefficients between Chl_a and SST and around zero or slightly negative correlation coefficients between Chl_a and wind is the most striking feature in the NoSoCS. The westward and eastward propagations of the Pearl River plume are both very small during the northeast monsoonal season, driven primarily by the Coriolis effect. The abrupt increase in the areal coverage of the River plume, which is much more pronounced in the eastward propagation, between June and August can be attributed to the prevailing southwest monsoon as well as the annual peak of the river flow. Coastal upwelling is another sub-regional phenomenon in the NoSoCS. The upwelling at the shelf edge off the Taiwan Bank may be characterized by its elevated Chl_a. Its areal coverage and average Chl_a do not vary

  6. Assessing the quality of bottom water temperatures from the Finite-Volume Community Ocean Model (FVCOM) in the Northwest Atlantic Shelf region

    Science.gov (United States)

    Li, Bai; Tanaka, Kisei R.; Chen, Yong; Brady, Damian C.; Thomas, Andrew C.

    2017-09-01

    The Finite-Volume Community Ocean Model (FVCOM) is an advanced coastal circulation model widely utilized for its ability to simulate spatially and temporally evolving three-dimensional geophysical conditions of complex and dynamic coastal regions. While a body of literature evaluates model skill in surface fields, independent studies validating model skill in bottom fields over large spatial and temporal scales are scarce because these fields cannot be remotely sensed. In this study, an evaluation of FVCOM skill in modeling bottom water temperature was conducted by comparison to hourly in situ observed bottom temperatures recorded by the Environmental Monitors on Lobster Traps (eMOLT), a program that attached thermistors to commercial lobster traps from 2001 to 2013. Over 2 × 106 pairs of FVCOM-eMOLT records were evaluated by a series of statistical measures to quantify accuracy and precision of the modeled data across the Northwest Atlantic Shelf region. The overall comparison between modeled and observed data indicates reliable skill of FVCOM (r2 = 0.72; root mean squared error = 2.28 °C). Seasonally, the average absolute errors show higher model skill in spring, fall and winter than summer. We speculate that this is due to the increased difficulty of modeling high frequency variability in the exact position of the thermocline and frontal zones. The spatial patterns of the residuals suggest that there is improved similarity between modeled and observed data at higher latitudes. We speculate that this is due to increased tidal mixing at higher latitudes in our study area that reduces stratification in winter, allowing improved model accuracy. Modeled bottom water temperatures around Cape Cod, the continental shelf edges, and at one location at the entrance to Penobscot Bay were characterized by relatively high errors. Constraints for future uses of FVCOM bottom water temperature are provided based on the uncertainties in temporal-spatial patterns. This study is

  7. Rift systems of the Russian Eastern Arctic shelf and Arctic deep water basins: link between geological history and geodynamics

    Directory of Open Access Journals (Sweden)

    A. M. Nikishin

    2017-01-01

    Full Text Available In our study, we have developed a new tectonic scheme of the Arctic Ocean, which is based mainly on seismic profiles obtained in the Arctic-2011, Arctic-2012 and Arctic-2014 Projects implemented in Russia. Having interpreted many seismic profiles, we propose a new seismic stratigraphy of the Arctic Ocean. Our main conclusions are drawn from the interpretation of the seismic profiles and the analysis of the regional geological data. The results of our study show that rift systems within the Laptev, the East Siberian and the Chukchi Seas were formed not earlier than Aptian. The geological structure of the Eurasian, Podvodnikov, Toll and Makarov Basins is described in this paper. Having synthesized all the available data on the study area, we propose the following model of the geological history of the Arctic Ocean: 1. The Canada Basin formed till the Aptian (probably, during Hauterivian-Barremian time. 2. During the Aptian-Albian, large-scale tectonic and magmatic events took place, including plume magmatism in the area of the De Long Islands, Mendeleev Ridge and other regions. Continental rifting started after the completion of the Verkhoyansk-Chukotka orogenу, and rifting occurred on the shelf of the Laptev, East Siberian, North Chukchi and South Chukchi basins, and the Chukchi Plateau; simultaneously, continental rifting started in the Podvodnikov and Toll basins. 3. Perhaps the Late Cretaceous rifting continued in the Podvodnikov and Toll basins. 4. At the end of the Late Cretaceous and Paleocene, the Makarov basin was formed by rifting, although local spreading of oceanic crust during its formation cannot be excluded. 5. The Eurasian Basin started to open in the Early Eocene. We, of course, accept that our model of the geological history of the Arctic Ocean, being preliminary and debatable, may need further refining. In this paper, we have shown a link between the continental rift systems on the shelf and the formation history of the Arctic

  8. Endmembers of Ice Shelf Melt

    Science.gov (United States)

    Boghosian, A.; Child, S. F.; Kingslake, J.; Tedesco, M.; Bell, R. E.; Alexandrov, O.; McMichael, S.

    2017-12-01

    Studies of surface melt on ice shelves have defined a spectrum of meltwater behavior. On one end the storage of meltwater in persistent surface ponds can trigger ice shelf collapse as in the 2002 event leading to the disintegration of the Larsen B Ice Shelf. On the other, meltwater export by rivers can stabilize an ice shelf as was recently shown on the Nansen Ice Shelf. We explore this dichotomy by quantifying the partitioning between stored and transported water on two glaciers adjacent to floating ice shelves, Nimrod (Antarctica) and Peterman (Greenland). We analyze optical satellite imagery (LANDSAT, WorldView), airborne imagery (Operation IceBridge, Trimetrogon Aerial Phototography), satellite radar (Sentinel-1), and digital elevation models (DEMs) to categorize surface meltwater fate and map the evolution of ice shelf hydrology and topographic features through time. On the floating Peterman Glacier tongue a sizable river exports water to the ocean. The surface hydrology of Nimrod Glacier, geometrically similar to Peterman but with ten times shallower surface slope, is dominated by storage in surface lakes. In contrast, the Nansen has the same surface slope as Nimrod but transports water through surface rivers. Slope alone is not the sole control on ice shelf hydrology. It is essential to track the storage and transport volumes for each of these systems. To estimate water storage and transport we analyze high resolution (40 cm - 2 m) modern and historical DEMs. We produce historical (1957 onwards) DEMs with structure-from-motion photogrammetry. The DEMs are used to constrain water storage potential estimates of observed basins and water routing/transport potential. We quantify the total volume of water stored seasonally and interannually. We use the normalize difference water index to map meltwater extent, and estimate lake water depth from optical data. We also consider the role of stored water in subsurface aquifers in recharging surface water after

  9. Modeled and measured glacier change and related glaciological, hydrological, and meteorological conditions at South Cascade Glacier, Washington, balance and water years 2006 and 2007

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2010-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance years 2006 and 2007. Mass balances were computed with assistance from a new model that was based on the works of other glacier researchers. The model, which was developed for mass balance practitioners, coupled selected meteorological and glaciological data to systematically estimate daily mass balance at selected glacier sites. The North Cascade Range in the vicinity of South Cascade Glacier accumulated approximately average to above average winter snow packs during 2006 and 2007. Correspondingly, the balance years 2006 and 2007 maximum winter snow mass balances of South Cascade Glacier, 2.61 and 3.41 meters water equivalent, respectively, were approximately equal to or more positive (larger) than the average of such balances since 1959. The 2006 glacier summer balance, -4.20 meters water equivalent, was among the four most negative since 1959. The 2007 glacier summer balance, -3.63 meters water equivalent, was among the 14 most negative since 1959. The glacier continued to lose mass during 2006 and 2007, as it commonly has since 1953, but the loss was much smaller during 2007 than during 2006. The 2006 glacier net balance, -1.59 meters water equivalent, was 1.02 meters water equivalent more negative (smaller) than the average during 1953-2005. The 2007 glacier net balance, -0.22 meters water equivalent, was 0.37 meters water equivalent less negative (larger) than the average during 1953-2006. The 2006 accumulation area ratio was less than 0.10, owing to isolated patches of accumulated snow that endured the 2006 summer season. The 2006 equilibrium line altitude was higher than the glacier. The 2007 accumulation area ratio and equilibrium line altitude were 0.60 and 1,880 meters, respectively. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The

  10. Evaluating trophic cascades as drivers of regime shifts in different ocean ecosystems

    Science.gov (United States)

    Pershing, Andrew J.; Mills, Katherine E.; Record, Nicholas R.; Stamieszkin, Karen; Wurtzell, Katharine V.; Byron, Carrie J.; Fitzpatrick, Dominic; Golet, Walter J.; Koob, Elise

    2015-01-01

    In ecosystems that are strongly structured by predation, reducing top predator abundance can alter several lower trophic levels—a process known as a trophic cascade. A persistent trophic cascade also fits the definition of a regime shift. Such ‘trophic cascade regime shifts' have been reported in a few pelagic marine systems—notably the Black Sea, Baltic Sea and eastern Scotian Shelf—raising the question of how common this phenomenon is in the marine environment. We provide a general methodology for distinguishing top-down and bottom-up effects and apply this methodology to time series from these three ecosystems. We found evidence for top-down forcing in the Black Sea due primarily to gelatinous zooplankton. Changes in the Baltic Sea are primarily bottom-up, strongly structured by salinity, but top-down forcing related to changes in cod abundance also shapes the ecosystem. Changes in the eastern Scotian Shelf that were originally attributed to declines in groundfish are better explained by changes in stratification. Our review suggests that trophic cascade regime shifts are rare in open ocean ecosystems and that their likelihood increases as the residence time of water in the system increases. Our work challenges the assumption that negative correlation between consecutive trophic levels implies top-down forcing.

  11. The effects of washing with Tamarind (Tamarindus indica L. water solution on shelf life of silver carp (Hypophthalmichthys molitrix fillet during refrigerator storage

    Directory of Open Access Journals (Sweden)

    Eshagh Zakipour Rahimabadi

    2016-01-01

    Full Text Available This study evaluated the antibacterial and antioxidant effects of tamarind water solution on shelf life of silver carp (Hypophthalmicthys molitrix fillet during refrigerator storage. Treatments of this study were unwashed samples (control, and samples washed with 1% and 2% tamarind water solution. Microbial, physicochemical and sensory analysis including total viable count (TVC, peroxide value (PV, thiobarbituric acid (TBA, total volatile base (TVB-N and pH were measured during 15 day storage at refrigerator (with 3 days intervals. Proximate analysis of samples also measured at day 0. TVC content was 0.93, 0.50 and 0.10 log CFU/g for control and treatments 1% and 2%, respectively and reached to 6.24, 5.82 and 5.21 log CFU/g at the end of storage period. At the end of storage period, the PV, TBA and TVB-N content were 8.4, 4.3, and 3.0 meq O2/Kg for control, 2.75, 1.35, and 0.50 mg/100g for 1% treatment, and 33.17, 23.90, and 22.10 mg N/100g for 2% treatment, respectively. This results showed the positive effect of tamarind to inhibit and delay fish fillet spoilage. According to sensory evaluation, the density of 1% tamarind was selected as the best density.

  12. Accumulation of 210Po by spiny dogfish (Squalus acanthias), elephant fish (Callorhinchus milii) and red gurnard (Chelodonichthys kumu) in New Zealand shelf waters

    International Nuclear Information System (INIS)

    Bellamy, P.; Hunter, K.A.

    1997-01-01

    Concentrations of the natural radionuclide 210 Po in the livers of 81 individual specimens of three fish species collected from waters of the Otago continental shelf, New Zealand, have been measured: spiny dogfish (Squalus acanthias), 4.2 ± 1.8 Bq kg -1 wet weight (mean ± standard deviation, n=48); elephant fish (Callorhinchus milii), 136 ± 39 Bq kg -1 (n = 7); and red gurnard (Chelodonichthys kumu), 38 ± 13 Bq kg -1 (n = 26). Separate measurements showed that only a negligible fraction of the 210 Po was supported by decay of the 210 Pb parent ( 210 Po/ 210 Pb activity ratios were 15, 134 and 5.9 respectively for the three species), indicating that direct uptake of 210 Po into the liver balances losses from excretion and radioactive decay. The radiation dose from 210 Po in the livers accounted for between 88% and 99% of the total internal absorbed dose received by the fish species. The activity of 210 Po in sea water from the study area was 0.9-2.2 mBq L -1 , yielding concentration factors for 210 Po in liver tissue in the range 3 x 103 to 100 x 103. No significant monophasic relationships were observed between the 210 Po results and the measured concentrations of the elements Cd, Cu, Fe, Mn, Zn and Pb, except that Pb and 210 Po were correlated (r = 0.511 ) in C. kumu. Copyright (1997) CSIRO Publishing

  13. Accumulation of 210 Po by spiny dogfish (Squalus acanthias), elephant fish (Callorhinchus milii) and red gurnard (Chelodonichthys kumu) in New Zealand shelf waters

    International Nuclear Information System (INIS)

    Peter Bellamy, P.; Hunter, K.A.

    1997-01-01

    Concentrations of the natural radionuclide 210 Po in the livers of 81 individual specimens of three fish species collected from waters of the Otago continental shelf, New Zealand, have been measured: spiny dogfish (Squalus acanthias), 4.2 ± 1.8 Bq kg -1 wet weight (mean ± standard deviation, n = 48); elephant fish (Callorhinchus milii), 136 ± 39 Bq kg -1 (n = 7); and red gurnard (Chelodonichthys kumu), 38 ± 13 Bq kg -1 (n = 26). Separate measurements showed that only a negligible fraction of the 210 Po was supported by decay of the 210 Pb parent ( 210 Po/ 210 Pb activity ratios were 15, 134 and 5.9 respectively for the three species), indicating that direct uptake of 210 Po into the liver balances losses from excretion and radioactive decay. The radiation dose from 210 Po in the livers accounted for between 88% and 99% of the total internal absorbed dose received by the fish species. The activity of 210 Po in sea water from the study area was 0.9-2.2 mBq L -1 , yielding concentration factors for 210 Po in liver tissue in the range 3 x 103 to 100 x 103. No significant monophasic relationships were observed between the 210 Po results and the measured concentrations of the elements Cd, Cu, Fe, Mn, Zn and Pb, except that Pb and 210 Po were correlated (r = 0.511) in C. kumu. 33 refs., 4 tabs., 1 fig

  14. Integrated fate modeling for exposure assessment of produced water on the Sable Island Bank (Scotian shelf, Canada).

    Science.gov (United States)

    Berry, Jody A; Wells, Peter G

    2004-10-01

    Produced water is the largest waste discharge from the production phase of oil and gas wells. Produced water is a mixture of reservoir formation water and production chemicals from the separation process. This creates a chemical mixture that has several components of toxic concern, ranging from heavy metals to soluble hydrocarbons. Analysis of potential environmental effects from produced water in the Sable Island Bank region (NS, Canada) was conducted using an integrated modeling approach according to the ecological risk assessment framework. A hydrodynamic dispersion model was used to describe the wastewater plume. A second fugacity-based model was used to describe the likely plume partitioning in the local environmental media of water, suspended sediment, biota, and sediment. Results from the integrated modeling showed that the soluble benzene and naphthalene components reach chronic no-effect concentration levels at a distance of 1.0 m from the discharge point. The partition modeling indicated that low persistence was expected because of advection forces caused by tidal currents for the Sable Island Bank system. The exposure assessment for the two soluble hydrocarbon components suggests that the risks of adverse environmental effects from produced water on Sable Island Bank are low.

  15. The seasonal evolution of shelf water masses around Bouvetøya, a sub-Antarctic island in the mid-Atlantic sector of the Southern Ocean, determined from an instrumented southern elephant seal

    Directory of Open Access Journals (Sweden)

    Andrew D. Lowther

    2016-10-01

    Full Text Available Our study makes use of a fortuitous oceanographic data set collected around the remote sub-Antarctic island of Bouvetøya by a conductivity–temperature–depth recorder (CTD integrated with a satellite-relayed data logger deployed on an adult female southern elephant seal (Mirounga leonina to describe the seasonal evolution of the western shelf waters. The instrumented seal remained in waters over the shelf for 259 days, collecting an average of 2.6 (±0.06 CTD profiles per day, providing hydrographic data encompassing the late austral summer and the entire winter. These data document the thermal stratification of the upper water layer due to summer surface heating of the previous year's Antarctic Surface Water, giving way to a cold subsurface layer at about 100 m as the austral winter progressed, with a concomitant increase in salinity of the upper layer. Upper Circumpolar Deep Water was detected at a depth of approximately 200 m along the western shelf of Bouvetøya throughout the year. These oceanographic data represent the only seasonal time series for this region and the second such animal–instrument oceanographic time series in the sub-Antarctic domain of the Southern Ocean.

  16. The Myanmar continental shelf

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Rao, P.S.

    reveal a minimum of 18 m thick strata of modern muds (Fig. 2g). At the outer boundary of the Gulf of Myanmar Continental Shelf 8 Martaban (15oN Latitude), brown muds overlie coarse sands indicating that modern deltaic sediments... on the Myeik Bank (Rodolfo, 1969a). Modern sediments on the Ayeyarwady shelf General composition, Texture and Grain-size: The distribution and sediment texture on the Ayeyarwady shelf shows fine-grained sediments comprising silty-clay and clayey...

  17. Water masses and mesoscale control on latitudinal and cross-shelf variations in larval fish assemblages off NW Africa

    Science.gov (United States)

    Olivar, M. Pilar; Sabatés, Ana; Pastor, Maria V.; Pelegrí, Josep L.

    2016-11-01

    We explore the associations between larval fish assemblages and oceanographic conditions in the upper ocean (top 200 m) along the African slope, from tropical (15°N) to subtropical (35°N) latitudes, during a period of intense upwelling. In this extensive region, the northward Mauritanian Current and Poleward Undercurrent carry South Atlantic Central Waters (SACW) while the southward Canary Upwelling Current transports North Atlantic Central Waters (NACW). South of Cape Blanc we only find SACW, and north of Cape Blanc there is NACW far offshore and a combination of NACW and SACW nearshore, separated by the Canary Upwelling Front (CUF). The larvae of different myctophid species serve as indicators of the water masses, e.g. S. veranyi and M. punctatum were found in some coastal stations that were dominated by NACW, while the tropical mesopelagic B. argyrogaster, H. macrochir, M. affine and S. kreffti were associated to the SACW. The along-slope offshore convergence of NACW and SACW takes place at the Cape Verde Frontal Zone (CVFZ), representing a region of extensive offshore export for larvae of coastal species, S. pilchardus and E. encrasicolus, far from their nearshore spawning area. The large-scale frontal systems (CVFZ and CUF) and mesoscale eddies contribute to retain larvae within productive waters, influencing both coastal and oceanic species.

  18. Deciphering complex dynamics of water counteraction around secondary structural elements of allosteric protein complex: Case study of SAP-SLAM system in signal transduction cascade.

    Science.gov (United States)

    Samanta, Sudipta; Mukherjee, Sanchita

    2018-01-28

    The first hydration shell of a protein exhibits heterogeneous behavior owing to several attributes, majorly local polarity and structural flexibility as revealed by solvation dynamics of secondary structural elements. We attempt to recognize the change in complex water counteraction generated due to substantial alteration in flexibility during protein complex formation. The investigation is carried out with the signaling lymphocytic activation molecule (SLAM) family of receptors, expressed by an array of immune cells, and interacting with SLAM-associated protein (SAP), composed of one SH2 domain. All atom molecular dynamics simulations are employed to the aqueous solutions of free SAP and SLAM-peptide bound SAP. We observed that water dynamics around different secondary structural elements became highly affected as well as nicely correlated with the SLAM-peptide induced change in structural rigidity obtained by thermodynamic quantification. A few instances of contradictory dynamic features of water to the change in structural flexibility are explained by means of occluded polar residues by the peptide. For βD, EFloop, and BGloop, both structural flexibility and solvent accessibility of the residues confirm the obvious contribution. Most importantly, we have quantified enhanced restriction in water dynamics around the second Fyn-binding site of the SAP due to SAP-SLAM complexation, even prior to the presence of Fyn. This observation leads to a novel argument that SLAM induced more restricted water molecules could offer more water entropic contribution during the subsequent Fyn binding and provide enhanced stability to the SAP-Fyn complex in the signaling cascade. Finally, SLAM induced water counteraction around the second binding site of the SAP sheds light on the allosteric property of the SAP, which becomes an integral part of the underlying signal transduction mechanism.

  19. Deciphering complex dynamics of water counteraction around secondary structural elements of allosteric protein complex: Case study of SAP-SLAM system in signal transduction cascade

    Science.gov (United States)

    Samanta, Sudipta; Mukherjee, Sanchita

    2018-01-01

    The first hydration shell of a protein exhibits heterogeneous behavior owing to several attributes, majorly local polarity and structural flexibility as revealed by solvation dynamics of secondary structural elements. We attempt to recognize the change in complex water counteraction generated due to substantial alteration in flexibility during protein complex formation. The investigation is carried out with the signaling lymphocytic activation molecule (SLAM) family of receptors, expressed by an array of immune cells, and interacting with SLAM-associated protein (SAP), composed of one SH2 domain. All atom molecular dynamics simulations are employed to the aqueous solutions of free SAP and SLAM-peptide bound SAP. We observed that water dynamics around different secondary structural elements became highly affected as well as nicely correlated with the SLAM-peptide induced change in structural rigidity obtained by thermodynamic quantification. A few instances of contradictory dynamic features of water to the change in structural flexibility are explained by means of occluded polar residues by the peptide. For βD, EFloop, and BGloop, both structural flexibility and solvent accessibility of the residues confirm the obvious contribution. Most importantly, we have quantified enhanced restriction in water dynamics around the second Fyn-binding site of the SAP due to SAP-SLAM complexation, even prior to the presence of Fyn. This observation leads to a novel argument that SLAM induced more restricted water molecules could offer more water entropic contribution during the subsequent Fyn binding and provide enhanced stability to the SAP-Fyn complex in the signaling cascade. Finally, SLAM induced water counteraction around the second binding site of the SAP sheds light on the allosteric property of the SAP, which becomes an integral part of the underlying signal transduction mechanism.

  20. Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Volume 2. Bering Sea. Revision

    Science.gov (United States)

    1988-01-01

    Joe D. Elms , for their editorial evaluation of the vironmental Assessmant Program. Additional depends to a large extent on weather condi- isopleth...waves, icing rates are open waters and coastal sectionsofAlaska.The temperatures less than 8°C, winds of 25 knots lower. icing causes slippery decks...thereby bias the oceanic climatology towards fair weather. A recent study by Elms (1986), in which he compared the Volunteer Observing Ship (VOS) data

  1. Modified, Packaged Tortillas Have Long Shelf Life

    Science.gov (United States)

    Bourland, Charles; Glaus-Late, Kimberly

    1995-01-01

    Tortillas made from modified recipe and sealed in low-pressure nitrogen in foil pouches in effort to increase their shelf life at room temperature. Preliminary tests show that shelf life of these tortillas at least five months; in contrast, commercial tortillas last only few days. Part of water in recipe replaced with glycerin. Particularly necessary to avoid Clostridium botulinum, which grows in anaerobic environments and produces deadly toxin that causes botulism.

  2. Turkish Straits System and Southern Black Sea: Exchange. Mixing and Shelf / Canyon Interactions

    Science.gov (United States)

    Özsoy, Emin; Gürses, Özgür; Tutsak, Ersin

    2015-04-01

    Based largely on an experiment employing high-resolution measurements carried out in June-July 2013 and re-interpretation of past experiments, the oceanographic variability of the exchange through the Turkish Straits System (TSS) and the interactions with the southern Black Sea are revealed through CTD, ADCP, oxygen and light transmission measurements. The exchange flow is primarily governed by the complex topography spanning two narrow straits, wide continental shelf regions, steep slopes and numerous canyons connecting deep basins. Water properties and currents in the high energy environment depends on the mosaic of fine-scale processes and pathways. The TSS, often approximated as a two-layer system has a hydraulically controlled, upper ocean and straits intensified regime, leading to surface jets and bottom plumes participating in mixing and renewal processes. The exit of the 'Mediterranean effluent' onto the Black Sea past a sill overflow from the Bosphorus passes through two subsequent hydraulic jumps and proceeds along a narrow canyon that veers to the west clear of the greater Bosphorus Canyon finally cascading down the few small canyons. A diffusive spread from the bottom vein of salty water reforms to the east and spills down the Bosphorus Canyon. The suspended particulate signature of the cascade, as well as its influence in hydrography is traced over the shelf and slope waters and through the numerous canyons into deep water where the reformed flow is found to sustain signatures of the past evolution of intrusive waters. An evaluation of the processes is given with reference to model development carried out in parallel to the analyses of the measurements.

  3. Community structure and ecological function of deep-water sponge grounds in the Traenadypet MPA—Northern Norwegian continental shelf

    Science.gov (United States)

    Kutti, Tina; Bannister, Raymond John; Fosså, Jan Helge

    2013-10-01

    Sponges within the 300 km2 Trænadypet coral MPA (Marine Protected Area) were mapped using photographic techniques. Three types of sponge communities were identified. The eastern side of the central circular depression was dominated by fan-shaped Phakellia ventilabrum sponges and further characterized by Mycale lingua and Oceanapia spp. sponges. Phakellia ventilabrum abundance (0.34 ind m-2) was positively correlated with the number of drop stones found. The western side of the depression was dominated by Geodia barretti, G. macandrewii and G. atlantica with an estimated average abundance of 0.40 ind m-2 and a biomass of 2.4 kg WW m-2. A third type of sponge community was found on both sides of the depression (in between the small scattered cold-water coral reefs constituting the MPA), which was characterized by Mycale lingua (0.20 ind m-2) and Oceanapia spp. (0.10 ind m-2), and which supported a high average Geodiidea biomass (1.6 kg WW m-2). The two last communities were both of the boreal ostur type and seemed to form continuous belts along the 2 km transects surveyed only interrupted by a few 15-30 m long empty patches. Within the MPA the average overall biomass of Geodiidea sponges was 1.8 kg WW m-2 and the overall sponge abundance was 1 ind m-2. Water pumping rates and respiration of Geodia barretti were measured, equating to 3000 l kg-1 DW day-1 and 1.5 μmol O2 g-1 DW h-1, respectively. Up-scaling this to the MPA as a whole suggests that the population of G. barretti alone could filter approximately 250 million m3 of water and consume 60 t of carbon daily. This demonstrates the important ecological function of sponges as nutrient vectors and points out the MPA as an ecologically significant area that should be carefully managed and monitored.

  4. Combination treatment of alkaline electrolyzed water and citric acid with mild heat to ensure microbial safety, shelf-life and sensory quality of shredded carrots.

    Science.gov (United States)

    Rahman, S M E; Jin, Yong-Guo; Oh, Deog-Hwan

    2011-05-01

    The objective of this study was to determine the synergistic effect of alkaline electrolyzed water and citric acid with mild heat against background and pathogenic microorganisms on carrots. Shredded carrots were inoculated with approximately 6-7 log CFU/g of Escherichia coli O157:H7 (932, and 933) and Listeria monocytogenes (ATCC 19116, and 19111) and then dip treated with alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaOCl), deionized water (DaIW), or 1% citric acid (CA) alone or with combinations of AlEW and 1% CA (AlEW + CA). The populations of spoilage bacteria on the carrots were investigated after various exposure times (1, 3, and 5 min) and treatment at different dipping temperatures (1, 20, 40, and 50 °C) and then optimal condition (3 min at 50 °C) was applied against foodborne pathogens on the carrots. When compared to the untreated control, treatment AcEW most effectively reduced the numbers of total bacteria, yeast and fungi, followed by AlEW and 100 ppm NaOCl. Exposure to all treatments for 3 min significantly reduced the numbers of total bacteria, yeast and fungi on the carrots. As the dipping temperature increased from 1 °C to 50 °C, the reductions of total bacteria, yeast and fungi increased significantly from 0.22 to 2.67 log CFU/g during the wash treatment (p ≤ 0.05). The combined 1% citric acid and AlEW treatment at 50 °C showed a reduction of the total bacterial count and the yeast and fungi of around 3.7 log CFU/g, as well as effective reduction of L. monocytogenes (3.97 log CFU/g), and E. Coli O157:H7 (4 log CFU/g). Combinations of alkaline electrolyzed water and citric acid better maintained the sensory and microbial quality of the fresh-cut carrots and enhanced the overall shelf-life of the produce. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Accumulation of {sup 210} Po by spiny dogfish (Squalus acanthias), elephant fish (Callorhinchus milii) and red gurnard (Chelodonichthys kumu) in New Zealand shelf waters

    Energy Technology Data Exchange (ETDEWEB)

    Peter Bellamy, P.; Hunter, K.A. [Department of Chemistry, University of Otago, Dunedin, (New Zealand)

    1997-09-01

    Concentrations of the natural radionuclide {sup 210} Po in the livers of 81 individual specimens of three fish species collected from waters of the Otago continental shelf, New Zealand, have been measured: spiny dogfish (Squalus acanthias), 4.2 {+-} 1.8 Bq kg {sup -1} wet weight (mean {+-} standard deviation, n = 48); elephant fish (Callorhinchus milii), 136 {+-} 39 Bq kg {sup -1} (n = 7); and red gurnard (Chelodonichthys kumu), 38 {+-} 13 Bq kg {sup -1} (n = 26). Separate measurements showed that only a negligible fraction of the {sup 210} Po was supported by decay of the {sup 210} Pb parent ( {sup 210} Po/{sup 210} Pb activity ratios were 15, 134 and 5.9 respectively for the three species), indicating that direct uptake of {sup 210} Po into the liver balances losses from excretion and radioactive decay. The radiation dose from {sup 210} Po in the livers accounted for between 88% and 99% of the total internal absorbed dose received by the fish species. The activity of {sup 210} Po in sea water from the study area was 0.9-2.2 mBq L {sup -1} , yielding concentration factors for {sup 210} Po in liver tissue in the range 3 x 103 to 100 x 103. No significant monophasic relationships were observed between the {sup 210} Po results and the measured concentrations of the elements Cd, Cu, Fe, Mn, Zn and Pb, except that Pb and {sup 210} Po were correlated (r = 0.511) in C. kumu. 33 refs., 4 tabs., 1 fig.

  6. Export of a Winter Shelf Phytoplankton Bloom at the Shelf Margin of Long Bay (South Atlantic Bight, USA)

    Science.gov (United States)

    Nelson, J.; Seim, H.; Edwards, C. R.; Lockhart, S.; Moore, T.; Robertson, C. Y.; Amft, J.

    2016-02-01

    A winter 2012 field study off Long Bay (seaward of Myrtle Beach, South Carolina) investigated exchange processes along the shelf margin. Topics addressed included mechanisms of nutrient input (upper slope to outer shelf), phytoplankton blooms and community characteristics (mid-to-outer shelf), and possible export of shelf bloom material (transport to and across the shelf break to the upper slope). Observations utilized three moorings (mid-shelf, shelf break, upper slope), two gliders and ship operations (repeat cruises with profiling, water sampling and towed body surveys) along with satellite SST and ocean color imagery and near-by NOAA buoy records. Here we focus on the late January to early February period, when a mid-shelf bloom of Phaeocystis globosa (which forms large gelatinous colonies) was transported to the shelf break. The presence of Phaeocystis colonies resulted in strong spiking in chlorophyll (chl) fluorescence profiles. A partitioning approach was adapted to estimate chl in colonies (spikes) and small forms (baseline signal) and to account for an apparent difference in measured in vivo fluorescence per unit chl (lower in colonies). Up to 40-50% of chl in the bloom (surface to bottom on the mid-shelf) was estimated to be in the colonies. In late January, there a pronounced seaward slumping of relatively dense mid-shelf water along the bottom under warmer surface water derived from the inshore edge of a broad jet of Gulf Stream water flowing southwestward along the upper slope. We describe the evolution of this event and the conditions which set up this mechanism for episodic near-bed transport of fresh bloom material produced on the shelf to the upper slope off Long Bay. Down-slope transport may have been enhanced in this case by the high phytoplankton biomass in gelatinous colonies, which appeared to be settling in the water column on the shelf prior to the transport event.

  7. Thermostable Shelf Life Study

    Science.gov (United States)

    Perchonok, M. H.; Antonini, D. K.

    2008-01-01

    The objective of this project is to determine the shelf life end-point of various food items by means of actual measurement or mathematical projection. The primary goal of the Advanced Food Technology Project in these long duration exploratory missions is to provide the crew with a palatable, nutritious and safe food system while minimizing volume, mass, and waste. The Mars missions could be as long as 2.5 years with the potential of the food being positioned prior to the crew arrival. Therefore, it is anticipated that foods that are used during the Mars missions will require a 5 year shelf life. Shelf life criteria are safety, nutrition, and acceptability. Any of these criteria can be the limiting factor in determining the food's shelf life. Due to the heat sterilization process used for the thermostabilized food items, safety will be preserved as long as the integrity of the package is maintained. Nutrition and acceptability will change over time. Since the food can be the sole source of nutrition to the crew, a significant loss in nutrition may determine when the shelf life endpoint has occurred. Shelf life can be defined when the food item is no longer acceptable. Acceptability can be defined in terms of appearance, flavor, texture, or aroma. Results from shelf life studies of the thermostabilized food items suggest that the shelf life of the foods range from 0 months to 8 years, depending on formulation.

  8. Thermostabilized Shelf Life Study

    Science.gov (United States)

    Perchonok, Michele H.; Catauro, Patricia M.

    2009-01-01

    The objective of this project is to determine the shelf life end-point of various food items by means of actual measurement or mathematical projection. The primary goal of the Advanced Food Technology Project in these long duration exploratory missions is to provide the crew with a palatable, nutritious and safe food system while minimizing volume, mass, and waste. The Mars missions could be as long as 2.5 years with the potential of the food being positioned prior to the crew arrival. Therefore, it is anticipated that foods that are used during the Mars missions will require a 5 year shelf life. Shelf life criteria are safety, nutrition, and acceptability. Any of these criteria can be the limiting factor in determining the food's shelf life. Due to the heat sterilization process used for the thermostabilized food items, safety will be preserved as long as the integrity of the package is maintained. Nutrition and acceptability will change over time. Since the food can be the sole source of nutrition to the crew, a significant loss in nutrition may determine when the shelf life endpoint has occurred. Shelf life can be defined when the food item is no longer acceptable. Acceptability can be defined in terms of appearance, flavor, texture, or aroma. Results from shelf life studies of the thermostabilized food items suggest that the shelf life of the foods range from 0 months to 8 years, depending on formulation.

  9. Cascade annealing: an overview

    International Nuclear Information System (INIS)

    Doran, D.G.; Schiffgens, J.O.

    1976-04-01

    Concepts and an overview of radiation displacement damage modeling and annealing kinetics are presented. Short-term annealing methodology is described and results of annealing simulations performed on damage cascades generated using the Marlowe and Cascade programs are included. Observations concerning the inconsistencies and inadequacies of current methods are presented along with simulation of high energy cascades and simulation of longer-term annealing

  10. MAPK cascades in guard cell signal transduction

    Directory of Open Access Journals (Sweden)

    Yuree eLee

    2016-02-01

    Full Text Available Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

  11. Downscaling, 2-way Nesting, and Data Assimilative Modeling in Coastal and Shelf Waters of the U.S. Mid-Atlantic Bight and Gulf of Maine

    Science.gov (United States)

    Wilkin, J.; Levin, J.; Lopez, A.; Arango, H.

    2016-02-01

    Coastal ocean models that downscale output from basin and global scale models are widely used to study regional circulation at enhanced resolution and locally important ecosystem, biogeochemical, and geomorphologic processes. When operated as now-cast or forecast systems, these models offer predictions that assist decision-making for numerous maritime applications. We describe such a system for shelf waters of the Mid-Atlantic Bight (MAB) and Gulf of Maine (GoM) where the MARACOOS and NERACOOS associations of U.S. IOOS operate coastal ocean observing systems that deliver a dense observation set using CODAR HF-radar, autonomous underwater glider vehicles (AUGV), telemetering moorings, and drifting buoys. Other U.S. national and global observing systems deliver further sustained observations from moorings, ships, profiling floats, and a constellation of satellites. Our MAB and GoM re-analysis and forecast system uses the Regional Ocean Modeling System (ROMS; myroms.org) with 4-dimensional Variational (4D-Var) data assimilation to adjust initial conditions, boundary conditions, and surface forcing in each analysis cycle. Data routinely assimilated include CODAR velocities, altimeter satellite sea surface height (with coastal corrections), satellite temperature, in situ CTD data from AUGV and ships (NMFS Ecosystem Monitoring voyages), and all in situ data reported via the WMO GTS network. A climatological data assimilative analysis of hydrographic and long-term mean velocity observations specifies the regional Mean Dynamic Topography that augments altimeter sea level anomaly data and is also used to adjust boundary condition biases that would otherwise be introduced in the process of downscaling from global models. System performance is described with respect to the impact of satellite, CODAR and in situ observations on analysis skill. Results from a 2-way nested modeling system that adds enhanced resolution over the NSF OOI Pioneer Array in the central MAB are also

  12. The Influence of Slope and Shelf Contour Currents On The Growth Pattern of A Cold-water Coral Mound Population Along The Margins of The Rockall Trough

    Science.gov (United States)

    Readman, P. W.; O'Reilly, B. M.; Shannon, P. M.; Jacob, A. W. B.

    The importance of bottom currents along the shelf and slope regions of northeast At- lantic basin margins in controlling sediment transport patterns and the development of carbonate mound ecosystems is now well recognised. The detailed structure of one such large carbonate mound population has been resolved along the western margin of the Porupine Bank west of Ireland with deep-tow (TOBI) sidescan. The mounds which comprise the population are circular to elliptical in shape, 50 - 850 m across and up to about 200 m high. Large scale sedimentary bedforms at 800 m water depth are inferred from backscatter zonation produced by strong NE-flowing contour currents. Streamlining effects control the shape of the mounds as they become more elliptical as their size increases. The frequency distribution follows a general power law which is determined by the biological growth rate of the mounds and the rate at which they colonise the substrate. At first bottom currents aid mound growth until they become so large that hydraulic drag forces retard their growth. In the recent past (late Pleistocene to present) if the number of mounds colonising the slope has increased exponentially with time while their growth rate slowed in response to fluid form drag forces, the observed population curve can be recovered. A model for evolution of the population predicts that these increased forces slow biological growth and cause a sharp fall-off in the number of mounds, also in agreement with observation. Correlation with late Pleistocene and Holocene climatic change suggests that the population is either very robust and relatively insensitive to major environmental change along the continental slope such as a change in current regime, or that the factors controlling its develop- ment were stable over large time intervals. This project was undertaken on behalf of the Irish Petroleum Infrastructure Programme.

  13. Optimization Design of Cascade Water Price for Rural Drinking Water Security Project%农村饮水安全工程阶梯水价优化设计

    Institute of Scientific and Technical Information of China (English)

    孔珂; 徐征和; 田守岗

    2011-01-01

    Rational water price necessitates to guarantee the smooth running of water supply project and to realize the sustainable security of rural drinking water. It is put forward that the two-stage cascade water price, which consists of survival water amount and living water amount, is suitable for current rural conditions. Such problems as the return of rural water supplier's cost, the water demand of customers, the definition of survival water amount, and the affordable ability of water price are analyzed, which provides fundamental for the establishment of the optimization model. The water price scheme of a rural water plant in Linqing of Shangdong is calculated as an example, and the result shows that this price scheme has positive practical value.%合理的水价是保障供水工程健康发展,实现可持续的农村饮水安全的必要条件.提出由生存水量和生活水量构成的2级阶梯水价是适合农村现状的水价模式;分析了农村供水工程的成本回收、用水户的用水需求、生存水量的核定,以及水价承受能力问题,在此基础上建立了阶梯水价优化模型;以山东临清某农村水厂为例进行了实例测算,结果表明该方案有积极的实施价值.

  14. Effect of incorporation of natural chemicals in water ice-glazing on freshness and shelf-life of Pacific saury (Cololabis saira) during -18 °C frozen storage.

    Science.gov (United States)

    Luo, Haibo; Wang, Weihua; Chen, Wei; Tang, Haiqing; Jiang, Li; Yu, Zhifang

    2017-12-14

    Microbial spoilage and lipid oxidation are two major factors causing freshness deterioration of Pacific saury (Cololabis saira) during frozen storage. To provide a remedy, the effects of several natural chemicals incorporated alone or in combination in traditional water ice-glazing on the freshness and shelf-life of Pacific saury during frozen storage at -18 °C were investigated. Pacific sauries were subjected to individual quick freezing followed immediately by dipping into cold tap water (control) or solutions containing nisin, chitosan, phytic acid (single-factor experiment) or their combinations ((L 9 (3 4 ) orthogonal experiment) for 10 s at 1 °C and then packaged in polypropylene bags before frozen storage at -18 °C. The storage duration tested was up to 12 months. All ice-glazing treatments with individual chemicals could significantly (P shelf-life of Pacific saury could be extended up to 12 months at -18 °C. The study indicated that the combination treatment with natural chemicals could be commercially utilized to maintain the freshness and prolong the shelf-life of Pacific saury. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  15. Assessment of the Water Quality of Jatiluhur Reservoir, the Downstream of Citarum Cascade River, Using Selected Physico-Chemical Parameters

    Directory of Open Access Journals (Sweden)

    Lieza Corsita

    2014-06-01

    Full Text Available Physico-chemistry and biological data were investigated  from  October 2010 until April 2011 of Jatiluhur reservoir. A total of six sampling stations were selected for this study. The discharge and hidrological data were obtained from Perum Jasa Tirta II Jatiluhur. The results showed that the hydrological regime in the reservoir Jatiluhur was affected by global phenomenon La Nina events in 2010 and early in 2011. Stream flows were determined during sampling to range from 78  to 482.5 m3/s. The water quality findings were as follows: pH (6.93-8.81, temperature (26.37-30.6°C, dissolved oxygen (0.733-5.2 mg/l, conductivity (2.45-233µmhos/cm, COD (7.36-96.9 mg/l, turbidity (4.063-65.6 NTU, total phosphate (0.002-0.324 mg/l, total nitrogen (0.99-5.96 mg/l, chlorophyl (2.237-43.37 mg/m3, visibility (30-160 cm. The eutrophication was pronounced at Jatiluhur reservoir. Canonical Correspendence Analysis found that some water quality parameters correlated positively with the discharge and the water level.

  16. Cascade Utilization of Energy in Solar Photovoltaic Hot Water System%太阳能光伏热水系统的能量梯级利用

    Institute of Scientific and Technical Information of China (English)

    关欣; 王艳迪; 向勇涛; 郭志波

    2012-01-01

    为了实现太阳能光伏发电系统中用于冷却太阳能电池的低品位热能利用,本文提出了太阳能光伏热水系统。通过对单体光伏光热系统(PV/T)的实验研究表明,在单体PV/T放置角度为30°,流量为200 L/h时,集热效率可达到最大值65.6%,系统的平均发电效率为14.3%,瞬时综合效率最大为83%,达到了能量的梯级利用。%To realize the use of low-grade thermal energy after cooling solar cells in solar photovoltaic systems,this paper puts forward a solar photovoltaic hot water system(PV/T).The experiment of the PV/T system shows,at the condition that inclination is 30°,and flow rate is 200 L/h,the maximum heat-collecting efficiency can be achieved at 65.6%and the average power generation efficiency is 14.3%, the maximum instantaneous overall efficiency is 83%,which realize the cascade utilization of energy.

  17. Infaunal macrobenthic community of soft bottom sediment in a tropical shelf

    Digital Repository Service at National Institute of Oceanography (India)

    Jayaraj, K.A.; Jacob, J.; DineshKumar, P.K.

    Studies of benthic communities in tropical shelf waters are limited. In this study, we deal with the infaunal benthic community of soft bottom sediment of the tropical eastern Arabian Sea shelf. Benthic macroinfauna was sampled with a Smith...

  18. Shelf life prediction of apple brownies using accelerated method

    Science.gov (United States)

    Pulungan, M. H.; Sukmana, A. D.; Dewi, I. A.

    2018-03-01

    The aim of this research was to determine shelf life of apple brownies. Shelf life was determined with Accelerated Shelf Life Testing method and Arrhenius equation. Experiment was conducted at 25, 35, and 45°C for 30 days. Every five days, the sample was analysed for free fatty acid (FFA), water activity (Aw), and organoleptic acceptance (flavour, aroma, and texture). The shelf life of the apple brownies based on FFA were 110, 54, and 28 days at temperature of 25, 35, and 45°C, respectively.

  19. Mean Lagrangian drift in continental shelf waves

    Science.gov (United States)

    Drivdal, M.; Weber, J. E. H.

    2012-04-01

    The time- and depth-averaged mean drift induced by barotropic continental shelf waves (CSW's) is studied theoretically for idealized shelf topography by calculating the mean volume fluxes to second order in wave amplitude. The waves suffer weak spatial damping due to bottom friction, which leads to radiation stress forcing of the mean fluxes. In terms of the total wave energy density E¯ over the shelf region, the radiation stress tensor component S¯11 for CSW's is found to be different from that of shallow water surface waves in a non-rotating ocean. For CSW's, the ratio ¯S11/¯E depends strongly on the wave number. The mean Lagrangian flow forced by the radiation stress can be subdivided into a Stokes drift and a mean Eulerian drift current. The magnitude of the latter depends on the ratio between the radiation stress and the bottom stress acting on the mean flow. When the effect of bottom friction acts equally strong on the waves and the mean current, calculations for short CSW's show that the Stokes drift and the friction-dependent wave-induced mean Eulerian current varies approximately in anti-phase over the shelf, and that the latter is numerically the largest. For long CSW's they are approximately in phase. In both cases the mean Lagrangian current, which is responsible for the net particle drift, has its largest numerical value at the coast on the shallow part of the shelf. Enhancing the effect of bottom friction on the Eulerian mean flow, results in a general current speed reduction, as well as a change in spatial structure for long waves. Applying realistic physical parameters for the continental shelf west of Norway, calculations yield along-shelf mean drift velocities for short CSW's that may be important for the transport of biological material, neutral tracers, and underwater plumes of dissolved oil from deep water drilling accidents.

  20. Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea.

    Science.gov (United States)

    Siemering, Beatrix; Bresnan, Eileen; Painter, Stuart C; Daniels, Chris J; Inall, Mark; Davidson, Keith

    2016-01-01

    The edge of the North West European Shelf (NWES) is characterised by a steep continental slope and a northward flowing slope current. These topographic/hydrographic features separate oceanic water and shelf water masses hence potentially separate phytoplankton communities. The slope current may facilitate the advective transport of phytoplankton, with mixing at the shelf edge supporting nutrient supply and therefore phytoplankton production. On the west Scottish shelf in particular, little is known about the phytoplankton communities in and around the shelf break and adjacent waters. Hence, to improve our understanding of environmental drivers of phytoplankton communities, biological and environmental data were collected on seven cross-shelf transects across the Malin and Hebridean Shelves during autumn 2014. Density profiles indicated that shelf break and oceanic stations had a 100 m deep mixed surface layer while stations on the shelf were generally well mixed. Analysis of similarity and multidimensional scaling of phytoplankton counts revealed that phytoplankton communities on the shelf were significantly different to those found at the shelf break and at oceanic stations. Shelf stations were dominated by dinoflagellates, with diatoms contributing a maximum of 37% of cells. Shelf break and oceanic stations were also dinoflagellate dominated but displayed a lower species diversity. Significant difference between shelf and shelf break stations suggested that the continental slope limited cross shelf phytoplankton exchange. Northern and southern phytoplankton communities on the shelf were approximately 15% dissimilar while there was no latitudinal gradient for stations along the slope current, suggesting this current provided south to north connectivity. Fitting environmental data to phytoplankton ordination showed a significant relationship between phytoplankton community dissimilarities and nutrient concentrations and light availability on the shelf compared to

  1. ANALISIS KADAR AIR DAN AKTIFITAS AIR KRITIKAL PRODUK SATA DARI MALAYSIA DAN IMPLIKASINYA PADA SIFAT-SIFAT PRODUK DAN UMUR SIMPANNYA [Analysis of Critical Moisture and Water Activity of Malaysian Sata and Its Implication to Product Characteristics and Shelf Life

    Directory of Open Access Journals (Sweden)

    Rita Hayati1

    2005-12-01

    Full Text Available Critical moisture and water activity of Sata. a Malaysian traditional food made of fish and young coconut meats, were analyzed for the first and second critical points of transition among the primary, secondary and tertiary bound water fractions in the Sata. It was found out that the first critical points of moisture content and water activity were M, of 5.09 % db (4.73 % wb and ar of 0.44 respectively. The second critical points were water content M5 of 19.38 % db(15.2 % wb and water activity as of 79 % respectively. The upper limit of he tertiary bound water (Mt was 75.3 % db (43.0 % wb. Sate sample in the primary bound water fraction (represented by moisture content at 5.0 % rib / 4.73 % wb, was stable in color and appearance, but slightly rancid due to molecular mobility of the liquid oil content The sample in the secondary bound water fraction (represented by moisture content of 15.0% db / 13.0% wb, has a color change to darker brown: and in the tertiary bound water fraction (represented by moisture of 30.5 % db / 23.4 % wb, mold growth appeared on the 10th day storage. The characteristics of the Malaysian Sate indicated an intermediate moisture food (IMF with water content of 37.5% wb, water activity of 0.9 and limited shelf tile to, few days at room temperature.

  2. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  3. Mechanisms of cascade collapse

    International Nuclear Information System (INIS)

    Diaz de la Rubia, T.; Smalinskas, K.; Averback, R.S.; Robertson, I.M.; Hseih, H.; Benedek, R.

    1988-12-01

    The spontaneous collapse of energetic displacement cascades in metals into vacancy dislocation loops has been investigated by molecular dynamics (MD) computer simulation and transmission electron microscopy (TEM). Simulations of 5 keV recoil events in Cu and Ni provide the following scenario of cascade collapse: atoms are ejected from the central region of the cascade by replacement collision sequences; the central region subsequently melts; vacancies are driven to the center of the cascade during resolidification where they may collapse into loops. Whether or not collapse occurs depends critically on the melting temperature of the metal and the energy density and total energy in the cascade. Results of TEM are presented in support of this mechanism. 14 refs., 4 figs., 1 tab

  4. Intra-annual variability of carbon and nitrogen stable isotopes in suspended organic matter in waters of the western continental shelf of India

    Directory of Open Access Journals (Sweden)

    M. V. Maya

    2011-11-01

    Full Text Available Intra-annual variations of δ13C and δ15N of water-column suspended particulate organic matter (SPOM have been investigated to understand the biogeochemical cycling of C and N in the Western Continental Shelf of India (WCSI. The key issues being addressed are: how the δ15N of SPOM is affected by seasonally varying processes of organic matter production and respiration and how it relates to the δ15N of sedimentary organic matter that appears to show a decreasing trend despite an apparent intensification of seasonal oxygen deficiency over the past few decades? A secondary objective was to evaluate the sources of organic carbon. Elemental carbon and nitrogen concentrations, C/N ratios in SPOM, along with ancillary chemical and biological variables including phytoplankton pigment abundance were also determined on a seasonal basis (from March 2007 to September 2008, with the partial exception of the southwest (SW monsoon period. The results reveal significant shifts in isotopic signatures, especially δ15N, of SPOM before and after the onset of SW monsoon. Very low δ15N values, reaching a minimum of −4.17 ‰, are found during the pre-monsoon period. Our results provide the first direct evidence for the addition of substantial amounts of isotopically light nitrogen by the diazotrophs, especially Trichodesmium, in the region. The δ15N of SPOM is generally lower than the mean value (7.38 ‰ for surficial sediments, presumably because of diagenetic enrichment. The results support the view that sedimentary δ15N may not necessarily reflect denitrification intensity in the overlying waters due to diverse sources of nitrogen and variability of its isotopic composition. The observed intra-annual variability of δ13C of SPOM during the pre-monsoon and post-monsoon periods is generally small. Phytoplankton production and probably species

  5. Outer Continental Shelf Lands Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data represents geographic terms used within the Outer Continental Shelf Lands Act (OCSLA or Act). The Act defines the United States outer continental shelf...

  6. Cascade energy amplifier

    International Nuclear Information System (INIS)

    Barzilov, A.P.; Gulevich, A.V.; Kukharchuk, O.F.

    2000-01-01

    The technical problem of long-life fission product and minor actinide incineration and production of plutonium fuel in the prospective nuclear systems will arise at significant scales of nuclear power industry development. Subcritical nuclear reactors driven by extemal neutron sources (energy amplifiers) are considered as incinerators of toxicity of complete nuclear industry. In the frames of this concept, the subcritical reactor part consisting of two coupled blanket regions (inner fast neutron spectrum core and outer thermal core) driven by extemal neutron source is discussed. Two types of source are studied: spallation target and 14-MeV fusion bum of micropellets. Liquid metal Pb-Bi is considered as target material and coolant of inner fast core. Thermal core is a heavy-water subcritical reactor of the Candu-type. The fast core is protected from thermal neutrons influence with the boron shield. All reactor technologies used in this concept are tested during years of operation and commercially available. Thus, the cascade energy amplifiers have a set of advantages in comparison with traditional concepts: in energy production, in transmutation efficiency, and in economics. (authors)

  7. Conjugation of cascades

    International Nuclear Information System (INIS)

    San Martin, Jesus; Rodriguez-Perez, Daniel

    2009-01-01

    Presented in this work are some results relative to sequences found in the logistic equation bifurcation diagram, which is the unimodal quadratic map prototype. All of the different saddle-node bifurcation cascades, associated with every last appearance p-periodic orbit (p=3,4,5,...), can also be generated from the very Feigenbaum cascade. In this way it is evidenced the relationship between both cascades. The orbits of every saddle-node bifurcation cascade, mentioned above, are located in different chaotic bands, and this determines a sequence of orbits converging to every band-merging Misiurewicz point. In turn, these accumulation points form a sequence whose accumulation point is the Myrberg-Feigenbaum point. It is also proven that the first appearance orbits in the n-chaotic band converge to the same point as the last appearance orbits of the (n + 1)-chaotic band. The symbolic sequences of band-merging Misiurewicz points are computed for any window.

  8. Learning optimal embedded cascades.

    Science.gov (United States)

    Saberian, Mohammad Javad; Vasconcelos, Nuno

    2012-10-01

    The problem of automatic and optimal design of embedded object detector cascades is considered. Two main challenges are identified: optimization of the cascade configuration and optimization of individual cascade stages, so as to achieve the best tradeoff between classification accuracy and speed, under a detection rate constraint. Two novel boosting algorithms are proposed to address these problems. The first, RCBoost, formulates boosting as a constrained optimization problem which is solved with a barrier penalty method. The constraint is the target detection rate, which is met at all iterations of the boosting process. This enables the design of embedded cascades of known configuration without extensive cross validation or heuristics. The second, ECBoost, searches over cascade configurations to achieve the optimal tradeoff between classification risk and speed. The two algorithms are combined into an overall boosting procedure, RCECBoost, which optimizes both the cascade configuration and its stages under a detection rate constraint, in a fully automated manner. Extensive experiments in face, car, pedestrian, and panda detection show that the resulting detectors achieve an accuracy versus speed tradeoff superior to those of previous methods.

  9. Nutrient Dynamics in the Northern South China Sea Shelf-sea (NoSoCS)

    Science.gov (United States)

    Wong, G. T.; Guo, X.

    2011-12-01

    The Northern South China Sea Shelf-sea (NoSoCS) is situated in the sub-tropics along the southern Chinese coast between the southern end of the Taiwan Strait and the Hainan Island. Samples were collected in four cross-shelf transects in summer, 2010 and two cross-shelf transects in winter, 2011 in this Shelf-sea. The shelf may be sub-divided into the inner shelf (1 μM in NO3- and >0.1 μM in soluble reactive phosphate) stretched across the shelf at least to the middle shelf. Thus, vertical mixing, even to relatively shallow depths, on the shelf may supply nutrients to and play a critical role in determining the primary production in the mixed layer. At least three such processes were observed. Through the year, internal waves of various strengths generated at the Luzon Strait propagated westward along the bottom of the mixed layer and dissipated along the middle and outer shelf. The effects of these waves were especially conspicuous north of the Dongsha Atoll and their action enhances vertical mixing. In the summer, upwelling occurred in the inner/middle shelf off Dongshan in response to the along shore southwest monsoon and the topographic forcing by the ridge extending offshore from Dongshan to the Taiwan Bank. In the winter, surface cooling and the strong northeast monsoon led to complete overturn in the shelf. The maximum density, reaching 24.6, in the surface waters was found offshore in the inner and middle shelf. This density was equivalent to the density of the water at >100 m offshore. As a result, this dense water also appeared as a layer of bottom water that extended across the shelf to the shelf edge.

  10. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  11. Energy cascades in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Hayden, A. C.; Brown, T. D.

    1979-03-15

    Combining energy uses in a cascade can result in significant overall reductions in fuel requirements. The simplest applications for a cascade are in the recovery of waste heat from existing processes using special boilers or turbines. Specific applications of more-complex energy cascades for Canada are discussed. A combined-cycle plant at a chemical refinery in Ontario is world leader in energy efficiency. Total-energy systems for commercial buildings, such as one installed in a school in Western Canada, offer attractive energy and operating cost benefits. A cogeneration plant proposed for the National Capital Region, generating electricity as well as steam for district heating, allows the use of a low-grade fossil fuel (coal), greatly improves energy-transformation efficiency, and also utilizes an effectively renewable resource (municipal garbage). Despite the widespread availability of equipment and technology of energy cascades, the sale of steam and electricity across plant boundaries presents a barrier. More widespread use of cascades will require increased cooperation among industry, electric utilities and the various levels of government if Canada is to realize the high levels of energy efficiency potential available.

  12. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.; Barlier, Vincent S.; Chin, Stephanie W.; Whited, Matthew T.; McAnally, R. Eric; Forrest, Stephen R.; Thompson, Mark E.

    2011-01-01

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  13. The exchange of inorganic carbon on the Canadian Beaufort Shelf

    Science.gov (United States)

    Mol, Jacoba; Thomas, Helmuth; Hu, Xianmin; Myers, Paul G.

    2017-04-01

    The Mackenzie Shelf in the southeastern Beaufort Sea is an area that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds and resulting cross-shelf Ekman transport. Downwelling carries inorganic carbon and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world oceans. Upwelling carries water high in dissolved inorganic carbon (DIC) and nutrients from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of inorganic carbon on the Mackenzie Shelf. The along-shore and cross-shelf transport of inorganic carbon is quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) model. A strong upwelling event prior to sampling on the Mackenzie Shelf is analyzed and the resulting influence on the carbonate system, including the saturation state of aragonite and pH levels, is investigated. TA and δ18O are used to examine water mass distributions in the study area and analyze the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of CO2 in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key in order to quantify the importance of Arctic shelf regions to the global carbon cycle and to provide a basis for understanding how its role will respond to the aforementioned changes in the regional marine system.

  14. Hadron cascades produced by electromagnetic cascades

    International Nuclear Information System (INIS)

    Nelson, W.R.; Jenkins, T.M.; Ranft, J.

    1986-12-01

    A method for calculating high energy hadron cascades induced by multi-GeV electron and photon beams is described. Using the EGS4 computer program, high energy photons in the EM shower are allowed to interact hadronically according to the vector meson dominance (VMD) model, facilitated by a Monte Carlo version of the dual multistring fragmentation model which is used in the hadron cascade code FLUKA. The results of this calculation compare very favorably with experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets (i.e., yields in secondary particle beam lines). Electron beam induced hadron star density contours are also presented and are compared with those produced by proton beams. This FLUKA-EGS4 coupling technique could find use in the design of secondary beams, in the determination high energy hadron source terms for shielding purposes, and in the estimation of induced radioactivity in targets, collimators and beam dumps

  15. Uncovering the glacial history of the Irish continental shelf (Invited)

    Science.gov (United States)

    Dunlop, P.; Benetti, S.; OCofaigh, C.

    2013-12-01

    In 1999 the Irish Government initiated a €32 million survey of its territorial waters known as the Irish National Seabed Survey (INSS). The INSS is amongst the largest marine mapping programmes ever undertaken anywhere in the world and provides high-resolution multibeam, backscatter and seismic data of the seabed around Ireland. These data have been used to provide the first clear evidence for extensive glaciation of the continental shelf west and northwest of Ireland. Streamlined drumlins on the mid to outer shelf record former offshore-directed ice flow towards the shelf edge and show that the ice sheet was grounded in a zone of confluence where ice flowing onto the shelf from northwest Ireland merged with ice flowing across the Malin Shelf from southwest Scotland. The major glacial features on the shelf are well developed nested arcuate moraine systems that mark the position of the ice sheet margin and confirm that the former British Irish Ice Sheet was grounded as far as the shelf edge around 100 km offshore of west Donegal at the last glacial maximum. Distal to the moraines, on the outermost shelf, prominent zones of iceberg plough marks give way to the Barra/Donegal fan and a well developed system of gullies and canyons which incise the continental slope. Since 2008 several scientific cruises have retrieved cores from the shelf and slope to help build a more detailed understanding of glacial events in this region. This presentation will provide an overview of the glacial history of the Irish shelf and will discuss ongoing research programmes that are building on the initial research findings to produce a better understanding of the nature and timing of ice sheet events in this region.

  16. Cascade reactor: introduction

    International Nuclear Information System (INIS)

    Pitts, J.H.

    1985-01-01

    Cascade is a concept for an ultrasafe, highly efficient, easily built reactor to convert inertial-confinement fusion energy into electrical power. The Cascade design includes a rotating double-cone-shaped chamber in which a moving, 1-m-thick ceramic granular blanket is held against the reactor wall by centrifugal action. The granular material absorbs energy from the fusion reactions. Accomplishments this year associated with Cascade included improvements to simplify chamber design and lower activation. The authors switched from a steel chamber wall to one made from silicon-carbide (SiC) panels held in compression by SiC-fiber/Al-composite tendons that gird the chamber both circumferentially and axially. The authors studies a number of heat-exchanger designs and selected a gravity-flow cascade design with a vacuum on the primary side. This design allows granules leaving the chamber to be transported to the heat exchangers using their own peripheral speed. The granules transfer their thermal energy and return to the chamber gravitationally: no vacuum locks or conveyors are needed

  17. Stability of cascade search

    Energy Technology Data Exchange (ETDEWEB)

    Fomenko, Tatiana N [M. V. Lomonosov Moscow State University, Faculty of Computational Mathematics and Cybernetics, Moscow (Russian Federation)

    2010-10-22

    We find sufficient conditions on a searching multi-cascade for a modification of the set of limit points of the cascade that satisfy an assessing inequality for the distance from each of these points to the initial point to be small, provided that the modifications of the initial point and the initial set-valued functionals or maps used to construct the multi-cascade are small. Using this result, we prove the stability (in the above sense) of the cascade search for the set of common pre-images of a closed subspace under the action of n set-valued maps, n{>=}1 (in particular, for the set of common roots of these maps and for the set of their coincidences). For n=2 we obtain generalizations of some results of A. V. Arutyunov; the very statement of the problem comes from a recent paper of his devoted to the study of the stability of the subset of coincidences of a Lipschitz map and a covering map.

  18. Hadronic cascade processes

    International Nuclear Information System (INIS)

    Ilgenfritz, E.M.; Kripfganz, J.; Moehring, H.J.

    1977-01-01

    The analytical treatment of hadronic decay cascades within the framework of the statistical bootstrap model is demonstrated on the basis of a simple variant. Selected problems for a more comprehensive formulation of the model such as angular momentum conservation, quantum statistical effects, and the immediate applicability to particle production processes at high energies are discussed in detail

  19. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  20. New Jersey shallow shelf

    DEFF Research Database (Denmark)

    Expedition 313 Scientists; Bjerrum, Christian J.

    2009-01-01

    to key horizons in wells drilled into the adjacent coastal plain suggest the clinoform structures investigated during Expedition 313 were deposited during times of oscillations in global sea level; however, this needs to be determined with much greater certainty. The age, lithofacies, and core-log......Integrated Ocean Drilling Program (IODP) Expedition 313 to the New Jersey Shallow Shelf off the east coast of the United States is the third IODP expedition to use a mission-specific platform. It was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO......) between 30 April and 17 July 2009, with additional support from the International Continental Scientific Drilling Program (ICDP). There were three objectives: (1) date late Paleogene–Neogene depositional sequences and compare ages of unconformable surfaces that divide these sequences with times of sea...

  1. Understanding Ice Shelf Basal Melting Using Convergent ICEPOD Data Sets: ROSETTA-Ice Study of Ross Ice Shelf

    Science.gov (United States)

    Bell, R. E.; Frearson, N.; Tinto, K. J.; Das, I.; Fricker, H. A.; Siddoway, C. S.; Padman, L.

    2017-12-01

    The future stability of the ice shelves surrounding Antarctica will be susceptible to increases in both surface and basal melt as the atmosphere and ocean warm. The ROSETTA-Ice program is targeted at using the ICEPOD airborne technology to produce new constraints on Ross Ice Shelf, the underlying ocean, bathymetry, and geologic setting, using radar sounding, gravimetry and laser altimetry. This convergent approach to studying the ice-shelf and basal processes enables us to develop an understanding of the fundamental controls on ice-shelf evolution. This work leverages the stratigraphy of the ice shelf, which is detected as individual reflectors by the shallow-ice radar and is often associated with surface scour, form close to the grounding line or pinning points on the ice shelf. Surface accumulation on the ice shelf buries these reflectors as the ice flows towards the calving front. This distinctive stratigraphy can be traced across the ice shelf for the major East Antarctic outlet glaciers and West Antarctic ice streams. Changes in the ice thickness below these reflectors are a result of strain and basal melting and freezing. Correcting the estimated thickness changes for strain using RIGGS strain measurements, we can develop decadal-resolution flowline distributions of basal melt. Close to East Antarctica elevated melt-rates (>1 m/yr) are found 60-100 km from the calving front. On the West Antarctic side high melt rates primarily develop within 10 km of the calving front. The East Antarctic side of Ross Ice Shelf is dominated by melt driven by saline water masses that develop in Ross Sea polynyas, while the melting on the West Antarctic side next to Hayes Bank is associated with modified Continental Deep Water transported along the continental shelf. The two sides of Ross Ice Shelf experience differing basal melt in part due to the duality in the underlying geologic structure: the East Antarctic side consists of relatively dense crust, with low amplitude

  2. Information cascade on networks

    Science.gov (United States)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  3. Cascade ICF power reactor

    International Nuclear Information System (INIS)

    Hogan, W.J.; Pitts, J.H.

    1986-01-01

    The double-cone-shaped Cascade reaction chamber rotates at 50 rpm to keep a blanket of ceramic granules in place against the wall as they slide from the poles to the exit slots at the equator. The 1 m-thick blanket consists of layers of carbon, beryllium oxide, and lithium aluminate granules about 1 mm in diameter. The x rays and debris are stopped in the carbon granules; the neutrons are multiplied and moderated in the BeO and breed tritium in the LiAlO 2 . The chamber wall is made up of SiO tiles held in compression by a network of composite SiC/Al tendons. Cascade operates at a 5 Hz pulse rate with 300 MJ in each pulse. The temperature in the blanket reaches 1600 K on the inner surface and 1350 K at the outer edge. The granules are automatically thrown into three separate vacuum heat exchangers where they give up their energy to high pressure helium. The helium is used in a Brayton cycle to obtain a thermal-to-electric conversion efficiency of 55%. Studies have been done on neutron activation, debris recovery, vaporization and recondensation of blanket material, tritium control and recovery, fire safety, and cost. These studies indicate that Cascade appears to be a promising ICF reactor candidate from all standpoints. At the 1000 MWe size, electricity could be made for about the same cost as in a future fission reactor

  4. Surficial sediments of the continental shelf off Karnataka

    Digital Repository Service at National Institute of Oceanography (India)

    Hashimi, N.H.; Nair, R.R.

    sediments occur betweenthe water depths of 15 to 50m corresponding to a distance of about 40 km from the coast. Beyond 50 m to the shelf edge are calcareous sands. Non-carbonate components of these deep water sands are essentially quartz, many of which...

  5. An approach to estimate the freshwater contribution from glacial melt and precipitation in East Greenland shelf waters using colored dissolved organic matter (CDOM)

    DEFF Research Database (Denmark)

    Stedmon, Colin; Granskog, Mats A.; Dodd, Paul A.

    2015-01-01

    Changes in the supply and storage of freshwater in the Arctic Ocean and its subsequent export to the North Atlantic can potentially influence ocean circulation and climate. In order to understand how the Arctic freshwater budget is changing and the potential impacts, it is important to develop......, and precipitation) and sea ice melt. We develop this approach further and investigate the use of an additional tracer, colored dissolved organic matter (CDOM), which is largely specific to freshwater originating from Arctic rivers. A robust relationship between the freshwater contribution from meteoric water...... processes (riverine input and sea ice formation), while previously, these waters where thought to be derived from open sea processes (cooling and sea ice formation) in the northern Barents and Kara Seas. In Greenlandic coastal waters the meteoric water contribution is influenced by Greenland ice sheet...

  6. Isotopic evidence for dead fish maintenance of Florida red tides, with implications for coastal fisheries over both source regions of the West Florida shelf and within downstream waters of the South Atlantic Bight

    Science.gov (United States)

    Walsh, J. J.; Weisberg, R. H.; Lenes, J. M.; Chen, F. R.; Dieterle, D. A.; Zheng, L.; Carder, K. L.; Vargo, G. A.; Havens, J. A.; Peebles, E.; Hollander, D. J.; He, R.; Heil, C. A.; Mahmoudi, B.; Landsberg, J. H.

    2009-01-01

    Toxic Florida red tides of the dinoflagellate Kareniabrevis have downstream consequences of 500-1000 km spatial extent. Fish stocks, shellfish beds, and harmful algal blooms of similar species occupy the same continental shelf waters of the southeastern United States, amounting to economic losses of more than 25 million dollars in some years. Under the aegis of the Center for Prediction of Red tides, we are now developing coupled biophysical models of the conditions that lead to red tides and impacted coastal fisheries, from the Florida Panhandle to Cape Hatteras. Here, a nitrogen isotope budget of the coastal food web of the West Florida shelf (WFS) and the downstream South Atlantic Bight (SAB) reaffirms that diazotrophs are the initial nutrient source for onset of red tides and now identifies clupeid fish as the major recycled nutrient source for their maintenance. The recent isotope budget of WFS and SAB coastal waters during 1998-2001 indicates that since prehistoric times of Timacua Indian settlements along the Georgia coast during 1075, ∼50% of the nutrients required for large red tides of >1 μg chl l -1 of K.brevis have been derived from nitrogen-fixers, with the other half from decomposing dead sardines and herrings. During 2001, >90% of the harvest of WFS clupeids was by large ichthyotoxic red tides of >10 μg chl l -1 of K.brevis, rather than by fishermen. After onset of the usual red tides in summer of 2006 and 2007, the simulated subsequent fall exports of Florida red tides in September 2007 to North Carolina shelf waters replicate observations of just ∼1 μg chl l -1 on the WFS that year. In contrast, the earlier red tides of >10 μg chl l -1 left behind off West Florida during 2006, with less physical export, are instead 10-fold larger than those of 2007. Earlier, 55 fish kills were associated with these coastal red tides during September 2006, between Tampa and Naples. Yet, only six fish kills were reported there in September 2007. With little

  7. Criticality safety study of shutdown diffusion cascade coolers

    International Nuclear Information System (INIS)

    Paschal, L.S.; Basoglu, B.; Bentley, C.L.; Dunn, M.E.

    1996-01-01

    Gaseous diffusion plants use cascade coolers in the production of highly enriched uranium (HEU) to remove heat from the enriched stream of UF 6 . The cascade coolers operate like shell and tube heat exchangers with the UF 6 on the shell side and Freon on the tube side. Recirculating cooling water (RCW) in condensers is used to cool the Freon. A criticality safety analysis was previously performed for cascade coolers during normal operation. The purpose of this paper is to evaluate several different hypothetical accidents regarding RCW ingress into the cooler to determine whether criticality safety concerns exist

  8. Oahutanais makalii, a new genus and species of colletteid tanaidacean (Crustacea, Peracarida) from shelf-waters off Hawaii, with a taxonomic key

    DEFF Research Database (Denmark)

    Morales-Núñz, Andrés G.; Larsen, Kim; Cooke, William J.

    2016-01-01

    A new colletteid tanaidacean, Oahutanais makalii gen. et sp. n., is described from Hawaiian coastal waters at depths ranging from 19 to 102 m. The new taxon is tentatively designated as a new genus, although it displays many features in common with the genus Leptognathiella. The new species is di...

  9. Cascading Corruption News

    DEFF Research Database (Denmark)

    Damgaard, Mads

    2018-01-01

    Through a content analysis of 8,800 news items and six months of front pages in three Brazilian newspapers, all dealing with corruption and political transgression, this article documents the remarkable skew of media attention to corruption scandals. The bias is examined as an information...... phenomenon, arising from systemic and commercial factors of Brazil’s news media: An information cascade of news on corruption formed, destabilizing the governing coalition and legitimizing the impeachment process of Dilma Rousseff. As this process gained momentum, questions of accountability were disregarded...

  10. Cascading Corruption News

    DEFF Research Database (Denmark)

    Damgaard, Mads

    2018-01-01

    Through a content analysis of 8,800 news items and six months of front pages in three Brazilian newspapers, all dealing with corruption and political transgression, this article documents the remarkable skew of media attention to corruption scandals. The bias is examined as an information...... phenomenon, arising from systemic and commercial factors of Brazil’s news media: An information cascade of news on corruption formed, destabilizing the governing coalition and legitimizing the impeachment process of Dilma Rousseff. As this process gained momentum, questions of accountability were disregarded...... by the media, with harmful effects on democracy....

  11. Geochemistry of sediments of the western Canadian continental shelf

    Science.gov (United States)

    Macdonald, R. W.; Pedersen, T. F.

    1991-08-01

    Few chemical data exist for the sedimentary environment off the Canadian west coast. Here we define the chemical nature of the shelf sediments by examining the important sources of material (natural and anthropogenic) to the region and processes relevant to diagenesis. Slightly more data exist for the continental shelf to the south (Washington) and north (Alaska), however it is clear that the sedimentary environment of these neighbouring shelves differs importantly from the Canadian portion. The British Columbia shelf receives little modern terrigenous detritus due mainly to isolation from terrestrial sediment sources by fiords, inland seas, or bypassing by shelf canyons. The chemical state of the sediments depends on the rate of supply of material, the energy of the depositional or erosional environment and the organic and inorganic composition of the material. These features in concert with bottom water characteristics control the redox state. Although no basins hosting continuous depositional records for the Holocene on the open British Columbia shelf have been identified or studied in a manner described by BUCKLEY ( Continental Shelf Research, 11, 1099-1122), some coastal embayments and fiords provide valuable historical records of post-glacial sedimentation. Such environments will prove to be increasingly useful in future studies of changes in regional climate and in establishing the chronology of natural disasters and anthropogenic impacts. Recommendations are given for a variety of research projects that would help us to understand better both chemical interactions at the seabed and Late Quaternary depositional history.

  12. Low-dose gamma irradiation following hot water immersion of papaya (Carica papaya linn.) fruits provides additional control of postharvest fungal infection to extend shelf life

    International Nuclear Information System (INIS)

    Rashid, M.H.A.; Grout, B.W.W.; Continella, A.; Mahmud, T.M.M.

    2015-01-01

    Low-dose gamma irradiation (0.08 kGy over 10 min), a level significantly below that required to satisfy the majority of international quarantine regulations, has been employed to provide a significant reduction in visible fungal infection on papaya fruit surfaces. This is appropriate for local and national markets in producer countries where levels of commercial acceptability can be retained despite surface lesions due to fungal infection. Irradiation alone and in combination with hot-water immersion (50 °C for 10 min) has been applied to papaya (Carica papaya L.) fruits at both the mature green and 1/3 yellow stages of maturity. The incidence and severity of surface fungal infections, including anthracnose, were significantly reduced by the combined treatment compared to irradiation or hot water treatment alone, extending storage at 11 °C by 13 days and retaining commercial acceptability. The combined treatment had no significant, negative impact on ripening, with quality characteristics such as surface and internal colour change, firmness, soluble solids, acidity and vitamin C maintained at acceptable levels. - Highlights: • Storage of papaya extended to 28 days whilst retaining commercial quality. • Additive effect of low gamma irradiation (0.08 kGy over 10 min) and hot-water treatment. • Significant reduction in surface fungal lesions. • No significant impact on colour change or flesh quality during storage

  13. Exchange across the shelf break at high southern latitudes

    Directory of Open Access Journals (Sweden)

    J. M. Klinck

    2010-05-01

    Full Text Available Exchange of water across the Antarctic shelf break has considerable scientific and societal importance due to its effects on circulation and biology of the region, conversion of water masses as part of the global overturning circulation and basal melt of glacial ice and the consequent effect on sea level rise. The focus in this paper is the onshore transport of warm, oceanic Circumpolar Deep Water (CDW; export of dense water from these shelves is equally important, but has been the focus of other recent papers and will not be considered here. A variety of physical mechanisms are described which could play a role in this onshore flux. The relative importance of some processes are evaluated by simple calculations. A numerical model for the Ross Sea continental shelf is used as an example of a more comprehensive evaluation of the details of cross-shelf break exchange. In order for an ocean circulation model to simulate these processes at high southern latitudes, it needs to have high spatial resolution, realistic geometry and bathymetry. Grid spacing smaller than the first baroclinic radius of deformation (a few km is required to adequately represent the circulation. Because of flow-topography interactions, bathymetry needs to be represented at these same small scales. Atmospheric conditions used to force these circulation models also need to be known at a similar small spatial resolution (a few km in order to represent orographically controlled winds (coastal jets and katabatic winds. Significantly, time variability of surface winds strongly influences the structure of the mixed layer. Daily, if not more frequent, surface fluxes must be imposed for a realistic surface mixed layer. Sea ice and ice shelves are important components of the coastal circulation. Ice isolates the ocean from exchange with the atmosphere, especially in the winter. Melting and freezing of both sea ice and glacial ice influence salinity and thereby the character of shelf

  14. The Faroe shelf circulation and its potential impact on the primary production

    Science.gov (United States)

    Rasmussen, Till A. S.; Olsen, Steffen M.; Hansen, Bogi; Hátún, Hjálmar; Larsen, Karin M. H.

    2014-10-01

    The ecosystem on the Faroe shelf has been shown to be tightly controlled by the primary production. It has been suggested that the primary production is governed by the physical processes controlling this water mass. The objective of this study is to identify the physical control mechanisms that control this water mass, link these to the interannual variability of the chlorophyll content on the Faroe shelf and through this discuss the influence on the primary production. In order to achieve this, a 10 year hindcast (2000-2009) with a regional ocean circulation model has been set up for the focus area. Results are compared with measurements on the Faroe shelf. The model reproduces the clockwise residual circulation around the Faroe Islands. The vertical velocity profile is validated using observations at a location west of the Islands. Observations show a logarithmic profile in the entire water column indicating a fully developed boundary layer. The modeled profile matches the observations in the bottom part of the water column, however the thickness of the bottom boundary layer is underestimated, which results in a constant profile in the upper part of the water column. As a consequence, the modeled velocity in the upper part of the water column is up to 20% lower than the observed velocity. The direction of the modeled velocity profile compares well with observations. The model realistically forms the partly isolated unique shelf water mass. Years with anomalously early and persistent modeled spring stratification correspond with years with a high on-shelf chlorophyll concentration. An integration of the exchange across the 120 m isobath shows intense water mass exchange across this depth contour. The major part of this includes tidal shifting of the front between on-shelf and off-shelf waters and is associated with little effective water mass exchange. The result is a shelf water mass that is relatively isolated. The modeled net exchange is constituted by an on-shelf

  15. Low-dose gamma irradiation following hot Water immersion of Papaya (Carica Papaya linn.) fruits provides additional control of postharvest fungal infection to extend shelf life

    DEFF Research Database (Denmark)

    Rashid, M.H.A.; Grout, Brian William Wilson; Continella, A.

    2015-01-01

    Low-dose gamma irradiation (0.08 kGy over 10 min), a level significantly below that required to satisfy the majority of international quarantine regulations, has been employed to provide a significant reduction in visible fungal infection on papaya fruit surfaces. This is appropriate for local an....... The combined treatment had no significant, negative impact on ripening, with quality characteristics such as surface and internal colour change, firmness, soluble solids, acidity and vitamin C maintained at acceptable levels....... and national markets in producer countries where levels of commercial acceptability can be retained despite surface lesions due to fungal infection. Irradiation alone and in combination with hot-water immersion (50 °C for 10 min) has been applied to papaya (Carica papaya L.) fruits at both the mature green...... and 1/3 yellow stages of maturity. The incidence and severity of surface fungal infections, including anthracnose, were significantly reduced by the combined treatment compared to irradiation or hot water treatment alone, extending storage at 11 °C by 13 days and retaining commercial acceptability...

  16. Dynamics of tidal and non-tidal currents along the southwest continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Aruna, C.; Ravichandran, C.; Srinivas, K.; Rasheed, P.A.A.; Lekshmi, S.

    are predominantly mixed, semidiurnal in nature. Motion over any continental shelf is governed by the tide-driven oscillatory flow. In this paper, tidal and non-tidal characteristics of the waters of Southwest continental shelf of India are assessed using...

  17. Unique 'man-made' object: reservoirs B10 and B11 of Techa cascade and means for in-situ measurement of its contamination - Water, soil, bottom sediments

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Oleg; Potapov, Victor; Stepanov, Vyacheslav; Smirnov, Sergey; Volkovich, Anatoly [National Research Centre - Kurchatov Institute, 1 Kurchatov Sq., Moscow (Russian Federation)

    2014-07-01

    Contamination of natural objects - alarm fallout zones and flood plains near production sites (the result of technological accidents and resource extraction) occupy large areas. Large area and volume of pollution, moderate activity facilities (at low and medium-level rad-wastes) to make such objects specific types of radioactive waste. These objects exist for a long time, now they are characterized by a bound state of nuclides with the matrix. There are no cost-effective ways to remove these rad-wastes, the only solution for the rehabilitation of such areas is their isolation and regular monitoring through direct and indirect measurements. The task of mapping and subsequent monitoring of pollution is very complex. Most of the complexity of the laboratory measurement techniques, as well as high levels of contamination (to 10{sup 9} Bk/m{sup 2}) for radionuclides Cs-137 and Sr-90 require for mapping pollution field physical methods of measurement of the specific activity of radionuclides directly on the ground. The set of instruments for in-situ contamination measurements: a portable spectrometric collimated detector, collimated borehole spectrometric detector, underwater spectrometric detector, spectrometer for field measurements of the specific activity of Sr-90, connected to a portable MCA. The complex was used in Bryansk region, on the Techa river and Yenisei river. We present measurements of contamination in and around the reservoir No. 10 of Techa cascade containing a huge amount of radioactive waste. Measurements are performed in the framework of international expeditions in 2008, 2011 and 2012. To develop plans and programs for the rehabilitation of non-standard large-size objects containing radioactive waste precise and detailed measurement data are necessary and very often there is not enough of such data. Measurements of contaminated water, soil and bottom sediments in area of water reservoirs of Techa cascade have shown that unique system of detectors and

  18. Cascade Error Projection Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.

    1995-01-01

    A detailed mathematical analysis is presented for a new learning algorithm termed cascade error projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters.

  19. Two new species of calcareous sponges (Porifera: Calcarea) from the deep Antarctic Eckström Shelf and a revised list of species found in Antarctic waters

    DEFF Research Database (Denmark)

    Rapp, Hans Tore; Göcke, Christian; Tendal, Ole Secher

    2013-01-01

    The paper reports on two new species of calcareous sponges (Porifera, Calcarea) from the Antarctic Weddell Sea, Clathrina brandtae sp. nov. and Leucetta delicata sp. nov., collected at 600 m depth during the ANT XXIV/2-SYSTCO expedition in January 2008. The new species are described based...... on a combination of morphological and molecular data. With these new additions the number of species of calcareous sponges reported from south of 50 degrees S (similar to south of the Polar Front) reaches 50 species. We report an exceptionally high degree of endemism within the group, and as many as 44 out...... of the 50 species of calcareous sponges are solely confined to Antarctic waters. An updated list of species of calcareous sponges from the area is provided....

  20. UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Directory of Open Access Journals (Sweden)

    J. Para

    2013-04-01

    Full Text Available Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC, and optical characteristics including UV (ultraviolet radiation and PAR (photosynthetically active radiation diffuse attenuation (Kd, and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM as part of the MALINA field campaign (30 July to 27 August. Spectral absorption coefficients (aCDOM (350 nm (m−1 were significantly correlated to both diffuse attenuation coefficients (Kd in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1–C3 were identified by fluorescence excitation/emission matrix spectroscopy (EEMS and parallel factor (PARAFAC analysis. Our results showed an aquatic dissolved organic matter (DOM component (C1, probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2 in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

  1. UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Science.gov (United States)

    Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

    2013-04-01

    Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV (ultraviolet) radiation and PAR (photosynthetically active radiation) diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM) by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence excitation/emission matrix spectroscopy (EEMS) and parallel factor (PARAFAC) analysis. Our results showed an aquatic dissolved organic matter (DOM) component (C1), probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

  2. UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Science.gov (United States)

    Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

    2012-11-01

    Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV and PAR diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m-2 for UV-B (305 nm), UV-A (380 nm) and PAR, respectively), we report significant light penetration with 10% irradiance depths (Z10% (λ)) reaching 9.5 m for 340 nm (UV-A) radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS) and PARAFAC analysis. Our results showed an in-situ biological component (C1) that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta sector, whereas the protein-like (C3) component dominated in the saltiest waters of the North East sector.

  3. Interband cascade lasers

    International Nuclear Information System (INIS)

    Vurgaftman, I; Meyer, J R; Canedy, C L; Kim, C S; Bewley, W W; Merritt, C D; Abell, J; Weih, R; Kamp, M; Kim, M; Höfling, S

    2015-01-01

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron–hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3–6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm −2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT. (topical review)

  4. Biological, physical and chemical properties at the Subtropical Shelf Front Zone in the SW Atlantic Continental Shelf

    Science.gov (United States)

    Muelbert, José H.; Acha, Marcelo; Mianzan, Hermes; Guerrero, Raúl; Reta, Raúl; Braga, Elisabete S.; Garcia, Virginia M. T.; Berasategui, Alejandro; Gomez-Erache, Mónica; Ramírez, Fernando

    2008-07-01

    The physical aspects of the Subtropical Shelf Front (STSF) for the Southwest Atlantic Continental Shelf were previously described. However, only scarce data on the biology of the front is available in the literature. The main goal of this paper is to describe the physical, chemical and biological properties of the STSF found in winter 2003 and summer 2004. A cross-section was established at the historically determined location of the STSF. Nine stations were sampled in winter and seven in summer. Each section included a series of conductivity-temperature-depth (CTD) stations where water samples from selected depths were filtered for nutrient determination. Surface samples were taken for chlorophyll a (Chl- a) determination and plankton net tows carried out above and below the pycnocline. Results revealed that winter was marked by an inner-shelf salinity front and that the STSF was located on the mid-shelf. The low salinity waters in the inner-shelf indicated a strong influence of freshwater, with high silicate (72 μM), suspended matter (45 mg l -1), phosphate (2.70 μM) and low nitrate (1.0 μM) levels. Total dissolved nitrogen was relatively high (22.98 μM), probably due to the elevated levels of organic compound contribution close to the continental margin. Surface Chl -a concentration decreased from coastal well-mixed waters, where values up to 8.0 mg m -3 were registered, to offshore waters. Towards the open ocean, high subsurface nutrients values were observed, probably associated to South Atlantic Central Waters (SACW). Zooplankton and ichthyoplankton abundance followed the same trend; three different groups associated to the inner-, mid- and outer-shelf region were identified. During summer, diluted waters extended over the shelf to join the STSF in the upper layer; the concentration of inorganic nutrients decreased in shallow waters; however, high values were observed between 40 and 60 m and in deep offshore waters. Surface Chl -a ranged 0.07-1.5 mg m -3

  5. ANTHROPOGENIC EUTROPHICATION IN THE RESERVOIR CASCADE OF THE MIDDLE PART OF KURA RIVER AS A RESULT OF WATER POLLUTION WITHIN GEORGIA

    Directory of Open Access Journals (Sweden)

    M. A. Salmanov

    2016-01-01

    Full Text Available Aim. Environmental effects of long-term fixed-pressure on ecosystem of the middle course of stability Kur in within Georgia it was noted by us 50 years ago in the first of the 4 reservoirs - Mingachevir, created in 1956. In 1959-1960. We noted the rapid development of phyto-bacterial, in the waters mouth of the rr. Kura Alazan (Ganikh and Iora (Gabyrry and later (after 9-11 years, in the area of the water. In the same time, anthropogenic eutrophication in the Shamkir reservoir which established upstream, occurred in the first years of the filling.Methods. To find out the reasons, causing intense phytoplankton, increasing the biological oxygen demand of water have been used methods determining the concentration of nutrient, the floristic composition of the dominant forms of phytoplankton, the value of its primary products, the degree of oxygen consumption in the form of the daily BOD.Results. Many years of research have shown, in all the reservoirs 4 causes of anthropogenic eutrophication are biostok of Kura River and increasing concentrations of allochthonous organic matter, which are the source of the waste water of cities and towns, industries located in the catchment area in Georgia.Conclusions. A result of receipt the river water, nutrients wore the stationary character, easily mineralized allochthonous origin of organic matter reservoir contributes to the generation of phyto-bacterial. This, adequately strengthened oxygen consumption of water microbiota, arise processes of hypoxia, which in coastal, relatively quiet areas leads to sustainable anaerobios.

  6. Radiation stress and mean drift in continental shelf waves

    Science.gov (United States)

    Weber, Jan Erik H.; Drivdal, Magnus

    2012-03-01

    The time- and depth-averaged mean drift induced by barotropic continental shelf waves (CSW's) is studied theoretically for idealized shelf topography by calculating the mean volume fluxes to second order in wave amplitude. The waves suffer weak spatial damping due to bottom friction, which leads to radiation stress forcing of the mean fluxes. In terms of the total wave energy density E̅̅ over the shelf region, the radiation stress tensor component S̅11 for CSW's is found to be different from that of shallow water surface waves in a non-rotating ocean. For CSW's, the ratio S̅11/E̅ depends strongly on the wave number. The mean Lagrangian flow forced by the radiation stress can be subdivided into a Stokes drift and a mean Eulerian drift current. The magnitude of latter depends on ratio between the radiation stress and the bottom stress acting on the mean flow. When the effect of bottom friction acts equally strong on the waves and the mean current, calculations for short CSW's show that the Stokes drift and the friction-dependent wave-induced mean Eulerian current varies approximately in anti-phase over the shelf, and that the latter is numerically the largest. For long CSW's they are approximately in phase. In both cases the mean Lagrangian current, which is responsible for the net particle drift, has its largest numerical value at the coast on the shallow part of the shelf. Enhancing the effect of bottom friction on the Eulerian mean flow, results in a general current speed reduction, as well as a change in spatial structure for long waves. Applying realistic physical parameters for the continental shelf west of Norway, calculations yield along-shelf mean drift velocities for short CSW's that may be important for the transport of biological material, neutral tracers, and underwater plumes of dissolved oil from deepwater drilling accidents.

  7. How fast is the Patagonian shelf-break acidifying?

    Science.gov (United States)

    Orselli, Iole B. M.; Kerr, Rodrigo; Ito, Rosane G.; Tavano, Virginia M.; Mendes, Carlos Rafael B.; Garcia, Carlos A. E.

    2018-02-01

    Anthropogenic carbon (Cant) concentration is determined according to the TrOCA method, from carbonate system data and hydrographic parameters collected during two consecutive spring cruises (2007 and 2008) in the Argentinean Patagonian shelf-break zone between 36°S and 50°S. Cant has intruded the water column until intermediate depths, with no Cant below 1000 m, in the deeper waters (i.e., North Atlantic Deep Water and Antarctic Bottom Water) of the Northern sector of the study area (i.e., North of 38°S). The higher Cant concentration is observed in Subantarctic Shelf Water in the Southern region, whereas in the Northern sector both Tropical Water and South Atlantic Central Water are equally affected by Cant intrusion. The Antarctic Intermediate Water represents the depth-limit achieved by Cant penetration, reinforcing the role that this water mass plays as an important vehicle to transport Cant to the oceans interior. The estimated Cant average (± method precision) is 46.6 ± 5.3 μmol kg- 1, considering the full depth of the water column. The ocean acidification state (ΔpH) shows an average (± standard deviation) of - 0.11 ± 0.05, thus, indicating an annual pH reduction of - 0.0010 yr- 1 since the Industrial Revolution (c.a. 1750). The degree of aragonite saturation is lowered towards undersaturation levels of calcite. The Patagonian shelf and shelf-break zones-a strong CO2 sink region in the global ocean-are likely a key area for Cant intrusion in the southwestern South Atlantic Ocean.

  8. Inferring network structure from cascades

    Science.gov (United States)

    Ghonge, Sushrut; Vural, Dervis Can

    2017-07-01

    Many physical, biological, and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we offer three topological methods to infer the structure of any directed network given a set of cascade arrival times. Our formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for several different cascade models.

  9. Reconstructing the trophic history of the Black Sea shelf

    Science.gov (United States)

    Yunev, Oleg; Velikova, Violeta; Carstensen, Jacob

    2017-11-01

    In the last 50 years the Black Sea has undergone large changes driven by increasing anthropogenic pressures. We estimated the integrated annual primary production (APP) for different shelf regions during the early eutrophication phase (1963-1976) using chlorophyll a and winter nitrate concentrations as proxy observations of primary production to describe its seasonal variation. For comparison, APP was estimated during the period when eutrophication peaked (1985-1992). In the early eutrophication period APP was estimated at 64-89 g C m-2 yr-1 for most part of the shelf, except the shelf part influenced by the Danube River (the shallow waters off the Romanian and Bulgarian coasts) where APP was ∼126 g C m-2 yr-1. In these two different shelf parts, APP increased to 138-190 and 266-318 g C m-2 yr-1 during the peak eutrophication period. These spatial differences are attributed to the large nutrient inputs from the Danube River. The APP estimates provide new insight into the eutrophication history of the Black Sea shelf, documenting stronger signs of eutrophiction than observed in other enclosed seas such as the Baltic Sea. Since the peak eutrophication period APP is estimated to have decreased by approximately 15-20%.

  10. Development and testing of a snow interceptometer to quantify canopy water storage and interception processes in the rain/snow transition zone of the North Cascades, Washington, USA

    Science.gov (United States)

    Martin, Kael A.; Van Stan, John T.; Dickerson-Lange, Susan E.; Lutz, James A.; Berman, Jeffrey W.; Gersonde, Rolf; Lundquist, Jessica D.

    2013-06-01

    Tree canopy snow interception is a significant hydrological process, capable of removing up to 60% of snow from the ground snowpack. Our understanding of canopy interception has been limited by our ability to measure whole canopy water storage in an undisturbed forest setting. This study presents a relatively inexpensive technique for directly measuring snow canopy water storage using an interceptometer, adapted from Friesen et al. (2008). The interceptometer is composed of four linear motion position sensors distributed evenly around the tree trunk. We incorporate a trunk laser-mapping installation method for precise sensor placement to reduce signal error due to sensor misalignment. Through calibration techniques, the amount of canopy snow required to produce the measured displacements can be calculated. We demonstrate instrument performance on a western hemlock (Tsuga heterophylla) for a snow interception event in November 2011. We find a snow capture efficiency of 83 ± 15% of accumulated ground snowfall with a maximum storage capacity of 50 ± 8 mm snow water equivalent (SWE). The observed interception event is compared to simulated interception, represented by the variable infiltration capacity (VIC) hydrologic model. The model generally underreported interception magnitude by 33% using a leaf area index (LAI) of 5 and 16% using an LAI of 10. The interceptometer captured intrastorm accumulation and melt rates up to 3 and 0.75 mm SWE h-1, respectively, which the model failed to represent. While further implementation and validation is necessary, our preliminary results indicate that forest interception magnitude may be underestimated in maritime areas.

  11. Analysis of the influence of reservoirs utilization to water quality profiles in Indonesia (Saguling - Jatiluhur) and Malaysia (Temengor - Chenderoh) with special references to cascade reservoirs

    Science.gov (United States)

    Subehi, Luki; Norasikin Ismail, Siti; Ridwansyah, Iwan; Hamid, Muzzalifah Abd; Mansor, Mashhor

    2018-02-01

    Tropical reservoir is the one ecosystem which is functioning in both ecological and economical services. As the settling of water volume, it harbors many species of fish. The objective of this study is to analyze the utilization and management of reservoirs related to their water quality conditions, represent by tropical reservoirs from Indonesia and Malaysia. Survey at Jatiluhur and Saguling (Indonesia) was conducted in March 2014 and September 2015, respectively while in Temengor and Chenderoh (Malaysia), the survey was done in January 2014 and April 2017, respectively. Based on elevation, Saguling and Temengor are upstream reservoirs. On the contrary, Jatiluhur and Chenderoh are downstream reservoirs. The results of the surveys in Jatiluhur and Saguling reservoirs showed that the average depths are 32.9m and 17.9m, respectively. On the other hand, Temengor and Chenderoh reservoirs are 100m and 16.2m, respectively. All of them play multi-functional roles including as a source of power plant, fisheries and tourism, as well as water sources for irrigation. In addition, Saguling and Temengor reservoirs are relatively dendritic in shape. In Indonesia, there are three consecutive reservoirs along Citarum River, whereas in Malaysia there are four consecutive reservoirs along Perak River. The results showed the potential impact of fish cages as pollutant, especially at Indonesian reservoirs. In addition, these tropical reservoirs have become famous tourism getaway. The capabilities of economic values of these reservoirs and ecosystem should be balanced. Basic ecological information is necessary for the next study.

  12. Coordination: southeast continental shelf studies. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, D.W.

    1981-02-01

    The objectives are to identify important physical, chemical and biological processes which affect the transfer of materials on the southeast continental shelf, determine important parameters which govern observed temporal and spatial varibility on the continental shelf, determine the extent and modes of coupling between events at the shelf break and nearshore, and determine physical, chemical and biological exchange rates on the inner shelf. Progress in meeting these research objectives is presented. (ACR)

  13. Ultrarelativistic cascades and strangeness production

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, D.E. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

    1998-08-24

    A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies {radical}(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.) 26 refs.

  14. Ultrarelativistic cascades and strangeness production

    International Nuclear Information System (INIS)

    Kahana, D.E.; Kahana, S.H.

    1998-01-01

    A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies √(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.)

  15. Ultrarelativistic cascades and strangeness production

    International Nuclear Information System (INIS)

    Kahana, D.E.; Kahana, S.H.

    1998-02-01

    A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy Ion-Ion collisions is applied to the production of strangeness at SPS energies. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS

  16. Cascade redox flow battery systems

    Science.gov (United States)

    Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

    2014-07-22

    A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

  17. Suspended particulate layers and internal waves over the southern Monterey Bay continental shelf: an important control on shelf mud belts?

    Science.gov (United States)

    Cheriton, Olivia M.; McPhee-Shaw, Erika E.; Shaw, William J.; Stanton, Timothy P.; Bellingham, James G.; Storlazzi, Curt D.

    2014-01-01

    Physical and optical measurements taken over the mud belt on the southern continental shelf of Monterey Bay, California documented the frequent occurrence of suspended particulate matter features, the majority of which were detached from the seafloor, centered 9–33 m above the bed. In fall 2011, an automated profiling mooring and fixed instrumentation, including a thermistor chain and upward-looking acoustic Doppler current profiler, were deployed at 70 m depth for 5 weeks, and from 12 to 16 October a long-range autonomous underwater vehicle performed across-shelf transects. Individual SPM events were uncorrelated with local bed shear stress caused by surface waves and bottom currents. Nearly half of all observed SPM layers occurred during 1 week of the study, 9–16 October 2011, and were advected past the fixed profiling mooring by the onshore phase of semidiurnal internal tide bottom currents. At the start of the 9–16 October period, we observed intense near-bed vertical velocities capable of lifting particulates into the middle of the water column. This “updraft” event appears to have been associated with nonlinear adjustment of high-amplitude internal tides over the mid and outer shelf. These findings suggest that nonlinear internal tidal motions can erode material over the outer shelf and that, once suspended, this SPM can then be transported shoreward to the middle and shallow sections of the mud belt. This represents a fundamental broadening of our understanding of how shelf mud belts may be built up and sustained.

  18. Impacts of a weather event on shelf circulation and CO2 and O2 dynamics on the Louisiana shelf during summer 2009

    Science.gov (United States)

    Huang, W.-J.; Cai, W.-J.; Wang, Y.; Hopkinson, C. S.

    2013-12-01

    While much is known about the physics of coastal currents, much less is known about the biogeochemical effects of surface currents on shelf carbon dioxide (CO2) and oxygen distribution and dynamics. The Mississippi and Atchafalaya River plume is usually observed along the Louisiana shelf with easterly winds. Such a typical pattern was observed in August 2007, i.e. a plume of low salinity and low partial pressure of CO2 (pCO2), indicating high biological production on the inner shelf; and higher salinity and pCO2 on the outer shelf. This high biological production induced by riverine nitrogen flux thus provided major organic matter sources for the shelf-wide hypoxia (dissolved oxygen [DO] hypoxic area. Furthermore, DIC concentration in bottom waters was higher than those predicted by the Redfield ratio, most likely because of much rapid O2 compensation than CO2 loss during air-sea exchange. Numerical models indicate such relocation of plume was mostly affected by the shelf circulation dominated by southerly and southwesterly winds. Consequently, we conclude that wind-forcing and shelf circulation are critical factors that influence the plume trajectories and the associated biogeochemical properties in coastal waters.

  19. Stochastic background of atmospheric cascades

    International Nuclear Information System (INIS)

    Wilk, G.; Wlodarczyk, Z.

    1993-01-01

    Fluctuations in the atmospheric cascades developing during the propagation of very high energy cosmic rays through the atmosphere are investigated using stochastic branching model of pure birth process with immigration. In particular, we show that the multiplicity distributions of secondaries emerging from gamma families are much narrower than those resulting from hadronic families. We argue that the strong intermittent like behaviour found recently in atmospheric families results from the fluctuations in the cascades themselves and are insensitive to the details of elementary interactions

  20. Computation of inverse magnetic cascades

    International Nuclear Information System (INIS)

    Montgomery, D.

    1981-10-01

    Inverse cascades of magnetic quantities for turbulent incompressible magnetohydrodynamics are reviewed, for two and three dimensions. The theory is extended to the Strauss equations, a description intermediate between two and three dimensions appropriate to tokamak magnetofluids. Consideration of the absolute equilibrium Gibbs ensemble for the system leads to a prediction of an inverse cascade of magnetic helicity, which may manifest itself as a major disruption. An agenda for computational investigation of this conjecture is proposed

  1. Mining of phosphorite resources from the Indian continental shelf will help food production

    Digital Repository Service at National Institute of Oceanography (India)

    Qasim, S.Z.; Nair, R.R.

    of phosphorite deposits would depend on several technical and economic factors Phosphorites occur in water depths upto 200 meters of the western continental shelf of India These are the areas associated with upwelling The relationship between phosphorite deposits...

  2. Impact of Savannah Harbor Deep Draft Navigation Project on Tybee Island Shelf and Shoreline

    National Research Council Canada - National Science Library

    Smith, Jane M; Stauble, Donald K; Williams, Brian P; Wutkowski, Michael J

    2008-01-01

    ... (including sand lost from the beach and the Tybee shelf). The study methodology includes numerical modeling of waves, currents, water levels, and sediment transport rates and sediment budgets analysis for pre-project and post- project conditions...

  3. Comparison of the Northeast Arctic cod year class strength (at the age of 3+) with the SST anomalies in main spawning ground (the Norwegian Shelf Waters) by results of analysis satellite monitoring data during last years.

    Science.gov (United States)

    Vanyushin, George

    2015-04-01

    Continuous long-term database (1998-2014) on the sea surface temperature (SST) comprising results of regional satellite monitoring (the Norwegian and the Barents seas) is used to resolve several applied problems. Authors have analyzed indirect influence the SST (the NOAA satellite data) on modern cod total stock biomass (abundance of the Northeast Arctic cod at age 3+). In this study, we went on the consideration of the relationship between the SST anomalies for March-April in the main spawning ground of the cod off the Lofoten islands in the Norwegian Shelf Waters and forecasting assessment of future cod generation success and its future abundance of 3 year old. Mean monthly SST and SST anomalies are computed for the selected area on the basis of the weekly SST maps which made by using the NOAA satellites data for the period 1998-2014. Comparison of the SST anomalies in the main spawning ground with abundance of the cod year class at age 3+ shows that survival of the cod generations was inhibited on the whole as negative (below -0,1C) well as positive SST anomalies (above +1,3C) during March and April. Finally, the results indicate that poor and low middle generations of cod at age 3+ (2002, 2004, 2010) occurred in years with negative or extremely high positive the SST anomalies in the spawning area. The SST anomalies in years which were close to normal significances provide conditions for appearance middle or strong generations of cod (2001-2003, 2005-2009, 2011-2013). So, the SST and SST anomalies (by the NOAA satellite data) characterize of increase in input of warm Atlantic waters which form numerous eddies along the main stream thus creating favorable conditions for spawning and development of the cod larvae and fry and provide them with food stock, finally direct influence on forming total stock biomass of cod and helping its population forecast. Key words: satellite monitoring of SST, the Northeast Arctic cod, spawning ground, forecast of the cod year class

  4. Atmospheric deposition, water-quality, and sediment data for selected lakes in Mount Rainer, North Cascades, and Olympic National Parks, Washington, 2008-10

    Science.gov (United States)

    Sheibley, Rich W.; Foreman, James R.; Moran, Patrick W.; Swarzenski, Peter W.

    2012-01-01

    To evaluate the potential effect from atmospheric deposition of nitrogen to high-elevation lakes, the U.S. Geological Survey partnered with the National Park Service to develop a "critical load" of nitrogen for sediment diatoms. A critical load is defined as the level of a given pollutant (in this case, nitrogen) at which detrimental effects to a target endpoint (sediment diatoms) result. Because sediment diatoms are considered one of the "first responders" to ecosystem changes from nitrogen, they are a sensitive indicator for nitrogen deposition changes in natural areas. This report presents atmospheric deposition, water quality, sediment geochronology, and sediment diatom data collected from July 2008 through August 2010 in support of this effort.

  5. Cascade Distiller System Performance Testing Interim Results

    Science.gov (United States)

    Callahan, Michael R.; Pensinger, Stuart; Sargusingh, Miriam J.

    2014-01-01

    The Cascade Distillation System (CDS) is a rotary distillation system with potential for greater reliability and lower energy costs than existing distillation systems. Based upon the results of the 2009 distillation comparison test (DCT) and recommendations of the expert panel, the Advanced Exploration Systems (AES) Water Recovery Project (WRP) project advanced the technology by increasing reliability of the system through redesign of bearing assemblies and improved rotor dynamics. In addition, the project improved the CDS power efficiency by optimizing the thermoelectric heat pump (TeHP) and heat exchanger design. Testing at the NASA-JSC Advanced Exploration System Water Laboratory (AES Water Lab) using a prototype Cascade Distillation Subsystem (CDS) wastewater processor (Honeywell d International, Torrance, Calif.) with test support equipment and control system developed by Johnson Space Center was performed to evaluate performance of the system with the upgrades as compared to previous system performance. The system was challenged with Solution 1 from the NASA Exploration Life Support (ELS) distillation comparison testing performed in 2009. Solution 1 consisted of a mixed stream containing human-generated urine and humidity condensate. A secondary objective of this testing is to evaluate the performance of the CDS as compared to the state of the art Distillation Assembly (DA) used in the ISS Urine Processor Assembly (UPA). This was done by challenging the system with ISS analog waste streams. This paper details the results of the AES WRP CDS performance testing.

  6. The Rocky Mountain Epidemic of Bark Beetles and Blue Stain Fungi Cause Cascading Effects on Coupled Water, C and N cycles

    Science.gov (United States)

    Ewers, B. E.; Pendall, E.; Norton, U.; Reed, D.; Franks, J.; Aston, T.; Whitehouse, F.; Barnard, H. R.; Brooks, P. D.; Angstmann, J.; Massman, W. J.; Williams, D. G.; Harpold, A. A.; Biederman, J.; Edburg, S. L.; Meddens, A. J.; Gochis, D. J.; Hicke, J. A.

    2010-12-01

    The ongoing epidemic of bark beetles and their associated xylem blocking blue-stain fungi is unprecedented in Rocky Mountain subalpine forests. As this epidemic continues, we seek to improve our predictive understanding of coupled water, C and N cycles by quantifying how these cycles may become uncoupled in response to the outbreak. Our specific questions are 1) how does the rapid drop in individual tree transpiration impact the temporal and spatial extent of evapotranspiration and 2) how does the subsequent increase in soil moisture and lower C inputs and N uptake impact soil C and N fluxes? We address these questions in two forest ecosystems using eddy covariance, sap flux, leaf gas exchange, plant hydraulic conductance, vegetation characteristics and soil trace gas measurements. We applied two sampling designs 1) subdivide the lodgepole pine forest spatially into varying degrees of bark beetle and blue stain infection and 2) follow the fluxes as the outbreak continues at a point in space encompassing the range of spatial variability in mortality. The first order impact of the bark beetle and blue stain fungi is dramatic in all tree species with a greater than 50% reduction in transpiration per tree within a month of infection. This change occurs even before the characteristic red tinge occurs in the needles or before the sapwood is stained blue. Leaf stomatal conductance declines more than either the biochemical or light harvesting components of photosynthesis immediately after infestation. The annual C sink at the spruce/fir forest has declined from -2.88 to -0.57 Mg C ha-1 yr-1 from 2006 to 2009. Annual evapotranspiration (ET) over the last five years at the spruce/fir forest now has an inverse relationship with precipitation because the last two years have seen a dramatic decrease (from 73 to 59 cm/year) in ET while precipitation has increased (from ~100 to 140 cm/year). Soil moisture in both forests has increased up to 100% within one growing season in

  7. Decadal variability on the Northwest European continental shelf

    Science.gov (United States)

    Jones, Sam; Cottier, Finlo; Inall, Mark; Griffiths, Colin

    2018-02-01

    Decadal scale time series of the shelf seas are important for understanding both climate and process studies. Despite numerous investigations of long-term temperature variability in the shelf seas, studies of salinity variability are few. Salt is a more conservative tracer than temperature in shallow seas, and it can reveal changes in local hydrographic conditions as well as transmitted basin-scale changes. Here, new inter-annual salinity time series on the northwest European shelf are developed and a 13 year high resolution salinity record from a coastal mooring in western Scotland is presented and analysed. We find strong temporal variability in coastal salinity on timescales ranging from tidal to inter-annual, with the magnitude of variability greatest during winter months. There is little seasonality and no significant decadal trend in the coastal time series of salinity. We propose 4 hydrographic states to explain salinity variance in the shelf area west of Scotland based on the interaction between a baroclinic coastal current and wind-forced barotropic flow: while wind forcing is important, we find that changes in the buoyancy-driven flow are more likely to influence long-term salinity observations. We calculate that during prevailing westerly wind conditions, surface waters in the Sea of the Hebrides receive a mix of 62% Atlantic origin water to 38% coastal sources. This contrasts with easterly wind conditions, during which the mix is 6% Atlantic to 94% coastal sources on average. This 'switching' between hydrographic states is expected to impact nutrient transport and therefore modify the level of primary productivity on the shelf. This strong local variability in salinity is roughly an order of magnitude greater than changes in the adjacent ocean basin, and we infer from this that Scottish coastal waters are likely to be resilient to decadal changes in ocean climate.

  8. The Cascade Drift Module: a GIS-based study on regional pesticide deposition

    NARCIS (Netherlands)

    Holterman, H.J.; Zande, van de J.C.

    2008-01-01

    The Cascade Project describes the modelling of spray drift and pesticide fate for a network of interconnected water bodies in a rural area. The present study concerns the first part of the proj ect, the Cascade Drift Module, which models the spatial and temporal distribution of deposits of spray

  9. Heat cascading regenerative sorption heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1995-01-01

    A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

  10. Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

    Science.gov (United States)

    Mol, Jacoba; Thomas, Helmuth; Myers, Paul G.; Hu, Xianmin; Mucci, Alfonso

    2018-02-01

    The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries dissolved inorganic carbon (DIC) and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world's oceans. Upwelling carries DIC and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of DIC are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf took place, bringing CO2-rich (elevated pCO2) water from the UHL onto the shelf bottom. The maximum on-shelf DIC flux was estimated at 16.9×103 mol C d-1 m-2 during the event. The maximum on-shelf transport of DIC through the upwelling event was found to be 65±15×10-3 Tg C d-1. TA and the oxygen isotope ratio of water (δ18O-H2O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will

  11. Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

    Directory of Open Access Journals (Sweden)

    J. Mol

    2018-02-01

    Full Text Available The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries dissolved inorganic carbon (DIC and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world's oceans. Upwelling carries DIC and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL onto the shelf. Profiles of DIC and total alkalinity (TA taken in August and September of 2014 are used to investigate the cycling of carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of DIC are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4 configuration of the Nucleus of European Modelling of the Ocean (NEMO framework. A strong upwelling event prior to sampling on the Mackenzie Shelf took place, bringing CO2-rich (elevated pCO2 water from the UHL onto the shelf bottom. The maximum on-shelf DIC flux was estimated at 16.9×103 mol C d−1 m−2 during the event. The maximum on-shelf transport of DIC through the upwelling event was found to be 65±15×10−3 Tg C d−1. TA and the oxygen isotope ratio of water (δ18O-H2O are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air–sea fluxes of carbon dioxide (CO2 in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis

  12. Time structure of cascade showers

    International Nuclear Information System (INIS)

    Nakatsuka, Takao

    1984-01-01

    Interesting results have been reported on the time structure of the electromagnetic components of air showers which have been obtained by using recent fast electronic circuit technology. However, these analyses and explanations seem not very persuasive. One of the reasons is that there is not satisfactory theoretical calculation yet to explain the delay of electromagnetic components in cascade processes which are the object of direct observation. Therefore, Monte Carlo calculation was attempted for examining the relationship between the altitude at which high energy γ-ray is generated up in the air and the time structure of cascade showers at the level of observation. The investigation of a dominant factor over the delay of electromagnetic components indicated that the delay due to the multiple scattering of electrons was essential. The author used the analytical solution found by himself of C. N. Yang's equation for the study on the delay due to multiple scattering. The results were as follows: The average delay time and the spread of distribution of electromagnetic cascades were approximately in linear relationship with the mass of a material having passed in a thin uniform medium; the rise time of arrival time distribution for electromagnetic cascade showers was very steep under the condition that they were generated up in the air and observed on the ground; the subpeaks delayed by tens of ns in arrival time may sometimes appear due to the perturbation in electromagnetic cascade processes. (Wakatsuki, Y.)

  13. Seabed geology of the Canadian eastern continental shelf

    Science.gov (United States)

    Piper, David J. W.

    1991-08-01

    The physiography of the continental shelf off eastern Canada is irregular, developed by glacial erosion of a previously fluvially-dominated landscape. Northern shelves are deeper than southern shelves. Most surficial sediments on the shelf are relict or palimpsest. The principal modern source of sediment to the northern shelves is ice rafting and iceberg scour reworking of Quaternary sediments. Southern shelves receive sediment through erosion of Quaternary sediments; only small amounts of fine-grained sediment derived from coastal erosion and rivers escape from the coastal zone. Regional maps of sediment texture, carbonate content and heavy mineralogy consequently show differences between the northern and southern shelves. Large areas of the shelf show little net deposition. On the northern shelves, there is a surface veneer up to 0.5 m thick derived from ice rafting and iceberg turbation of underlying Quaternary sediment, modified by south-flowing currents [ WOODWORTH-LYNASet al. (this issue) Continental Shelf Research, 11, 939-961]. The overall effects of former iceberg turbation may extend to a depth of 10 m sub-bottom. On the southern shelves, bioturbation and perhaps storm-related currents rework exposed Quaternary sediments more slowly. Muds accumulate in deep basins on the shelves at rates of about 0.5 m per 1000 years; this accumulation is probably episodic and related to major storms reworking sediment from the surface sediment veneer in shallower areas of little net deposition. In water depths less than 110 m sand and gravel have formed as a result of reworking in the coastal zone during the post-glacial transgression. Over large areas of Georges Bank, the eastern Scotian Shelf and the Grand Banks of Newfoundland, such sands are mobilized during storms to form a wide suite of bedforms [ AMOS and JUDGE (this issue) Continental Shelf Research, 11, 1037-1068]. Elsewhere, particularly in deeper water, sandy surfaces appear moribund or inactive and large

  14. Brown, C.A., D. Sharp, and T. Mochon Collura. 2016. Effect of Climate Change on Water Temperature and Attainment of Water Temperature Criteria in the Yaquina Estuary, Oregon (USA). Estuarine, Coastal and Shelf Science. 169:136-146.

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains the research described in the following publication: Brown, C.A., D. Sharp, and T. Mochon Collura. 2016. Effect of Climate Change on Water...

  15. Rescuing Ecosystems from Extinction Cascades

    Science.gov (United States)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  16. Planning of cascade stations on the Maotiao He detailed

    Energy Technology Data Exchange (ETDEWEB)

    Guan, W

    1984-09-20

    Details of the hydroelectric power stations on the Maotiao He cascades and examples of how some problems were resolved begin with a description of the river basin survey for topographical features, hydrometeorological conditions, and geological conditions. The river characteristics survey was the basis for planning the cascade power stations and the selection of installed capacity at each station. The review also covers discharge and flood control planning based on rainfall data and the composition of flood areas. The overall development program emphasizes power generation, but also includes irrigation, industrial water supply, and tourism. 2 figures, 1 table.

  17. Cascade: a high-efficiency ICF power reactor

    International Nuclear Information System (INIS)

    Pitts, J.H.

    1985-01-01

    Cascade attains a net power-plant efficiency of 49% and its cost is competitive with high-temperature gas-cooled reactor, pressurized-water reactor, and coal-fired power plants. The Cascade reactor and blanket are made of ceramic materials and activation is 6 times less than that of the MARS Tandem Mirror Reactor operating at comparable power. Hands-on maintenance of the heat exchangers is possible one day after shutdown. Essentially all tritium is recovered in the vacuum system, with the remainder recovered from the helium power conversion loop. Tritium leakage external to the vacuum system and power conversion loop is only 0.03 Ci/d

  18. Ice-Shelf Tidal Flexure and Subglacial Pressure Variations

    Science.gov (United States)

    Walker, Ryan T.; Parizek, Byron R.; Alley, Richard B.; Anandakrishnan, Sridhar; Riverman, Kiya L.; Christianson, Knut

    2013-01-01

    We develop a model of an ice shelf-ice stream system as a viscoelastic beam partially supported by an elastic foundation. When bed rock near the grounding line acts as a fulcrum, leverage from the ice shelf dropping at low tide can cause significant (approx 1 cm) uplift in the first few kilometers of grounded ice.This uplift and the corresponding depression at high tide lead to basal pressure variations of sufficient magnitude to influence subglacial hydrology.Tidal flexure may thus affect basal lubrication, sediment flow, and till strength, all of which are significant factors in ice-stream dynamics and grounding-line stability. Under certain circumstances, our results suggest the possibility of seawater being drawn into the subglacial water system. The presence of sea water beneath grounded ice would significantly change the radar reflectivity of the grounding zone and complicate the interpretation of grounded versus floating ice based on ice-penetrating radar observations.

  19. Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer

    Directory of Open Access Journals (Sweden)

    C. Wegner

    2013-02-01

    Full Text Available Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic. To study the interannual variability of suspended particulate matter (SPM dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea shelf, detailed oceanographic, optical (turbidity and Ocean Color satellite data, and hydrochemical (nutrients, SPM, stable oxygen isotopes process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented.

    The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the southeastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the central and northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore winds and northward transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf, whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport, in both the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during the open water season. A continuing trend toward

  20. The weeding handbook a shelf-by-shelf guide

    CERN Document Server

    Vnuk, Rebecca

    2015-01-01

    "No! We can't rid of that!" Vnuk, author of the popular "Weeding Tips" column on Booklist Online, is here to show you that yes, you can. A library is an ever-changing organism; when done the right way, weeding helps a library thrive by focusing its resources on those parts of the collection that are the most useful to its users. Her handbook takes the guesswork out of this delicate but necessary process, giving public and school library staff the knowledge and the confidence to effectively weed any collection, of any size. Going through the proverbial stacks shelf by shelf, Vnuk: Explains why weeding is important for a healthy library, demonstrating that a vibrant collection leads to robust circulation, which in turn affects library budgets Walks readers through a library's shelves by Dewey area, with recommended weeding criteria and call-outs in each area for the different considerations of large collections and smaller collections Features a chapter addressing reference, media, magazines and newspapers, e-b...

  1. Variability of Basal Melt Beneath the Pine Island Glacier Ice Shelf, West Antarctica

    Science.gov (United States)

    Bindschadler, Robert; Vaughan, David G.; Vornberger, Patricia

    2011-01-01

    Observations from satellite and airborne platforms are combined with model calculations to infer the nature and efficiency of basal melting of the Pine Island Glacier ice shelf, West Antarctica, by ocean waters. Satellite imagery shows surface features that suggest ice-shelf-wide changes to the ocean s influence on the ice shelf as the grounding line retreated. Longitudinal profiles of ice surface and bottom elevations are analyzed to reveal a spatially dependent pattern of basal melt with an annual melt flux of 40.5 Gt/a. One profile captures a persistent set of surface waves that correlates with quasi-annual variations of atmospheric forcing of Amundsen Sea circulation patterns, establishing a direct connection between atmospheric variability and sub-ice-shelf melting. Ice surface troughs are hydrostatically compensated by ice-bottom voids up to 150m deep. Voids form dynamically at the grounding line, triggered by enhanced melting when warmer-than-average water arrives. Subsequent enlargement of the voids is thermally inefficient (4% or less) compared with an overall melting efficiency beneath the ice shelf of 22%. Residual warm water is believed to cause three persistent polynyas at the ice-shelf front seen in Landsat imagery. Landsat thermal imagery confirms the occurrence of warm water at the same locations.

  2. Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer.

    Science.gov (United States)

    Henley, Sian F; Jones, Elizabeth M; Venables, Hugh J; Meredith, Michael P; Firing, Yvonne L; Dittrich, Ribanna; Heiser, Sabrina; Stefels, Jacqueline; Dougans, Julie

    2018-06-28

    The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Authors.

  3. On the shelf life of pharmaceutical products.

    Science.gov (United States)

    Capen, Robert; Christopher, David; Forenzo, Patrick; Ireland, Charles; Liu, Oscar; Lyapustina, Svetlana; O'Neill, John; Patterson, Nate; Quinlan, Michelle; Sandell, Dennis; Schwenke, James; Stroup, Walter; Tougas, Terrence

    2012-09-01

    This article proposes new terminology that distinguishes between different concepts involved in the discussion of the shelf life of pharmaceutical products. Such comprehensive and common language is currently lacking from various guidelines, which confuses implementation and impedes comparisons of different methodologies. The five new terms that are necessary for a coherent discussion of shelf life are: true shelf life, estimated shelf life, supported shelf life, maximum shelf life, and labeled shelf life. These concepts are already in use, but not named as such. The article discusses various levels of "product" on which different stakeholders tend to focus (e.g., a single-dosage unit, a batch, a production process, etc.). The article also highlights a key missing element in the discussion of shelf life-a Quality Statement, which defines the quality standard for all key stakeholders. Arguments are presented that for regulatory and statistical reasons the true product shelf life should be defined in terms of a suitably small quantile (e.g., fifth) of the distribution of batch shelf lives. The choice of quantile translates to an upper bound on the probability that a randomly selected batch will be nonconforming when tested at the storage time defined by the labeled shelf life. For this strategy, a random-batch model is required. This approach, unlike a fixed-batch model, allows estimation of both within- and between-batch variability, and allows inferences to be made about the entire production process. This work was conducted by the Stability Shelf Life Working Group of the Product Quality Research Institute.

  4. Swell propagation across a wide continental shelf

    OpenAIRE

    Hendrickson, Eric J.

    1996-01-01

    The effects of wave refraction and damping on swell propagation across a wide continental shelf were examined with data from a transect of bottom pressure recorders extending from the beach to the shelf break near Duck, North Carolina. The observations generally show weak variations in swell energy across the shelf during benign conditions, in qualitative agreement with predictions of a spectral refraction model. Although the predicted ray trajectories are quite sensitive to the irregular she...

  5. Whither the UK Continental Shelf?

    International Nuclear Information System (INIS)

    Kemp, A.G.

    1999-01-01

    The development of the oil and gas fields on the United Kingdom continental shelf has been carried out with remarkable success. However, low oil prices now threaten fresh investment and make it likely that both oil and gas output will start to fall in about 2001. The impact of a number of different price scenarios on further development is assessed. It is concluded that continuing technological improvements and the provision of adequate incentives by government should ensure a long productive future for the province. (UK)

  6. INCAS: an analytical model to describe displacement cascades

    Energy Technology Data Exchange (ETDEWEB)

    Jumel, Stephanie E-mail: stephanie.jumel@edf.fr; Claude Van-Duysen, Jean E-mail: jean-claude.van-duysen@edf.fr

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  7. INCAS: an analytical model to describe displacement cascades

    Science.gov (United States)

    Jumel, Stéphanie; Claude Van-Duysen, Jean

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  8. INCAS: an analytical model to describe displacement cascades

    International Nuclear Information System (INIS)

    Jumel, Stephanie; Claude Van-Duysen, Jean

    2004-01-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory

  9. Shelf life of electronic/electrical devices

    International Nuclear Information System (INIS)

    Polanco, S.; Behera, A.K.

    1993-01-01

    This paper discusses inconsistencies which exist between various industry practices regarding the determination of shelf life for electrical and electronic components. New methodologies developed to evaluate the shelf life of electrical and electronic components are described and numerous tests performed at Commonwealth Edison Company's Central Receiving Inspection and Testing (CRIT) Facility are presented. Based upon testing and analysis using the Arrhenius methodology and typical materials used in the manufacturing of electrical and electronic components, shelf life of these devices was determined to be indefinite. Various recommendations to achieve an indefinite. Various recommendations to achieve an indefinite shelf life are presented to ultimately reduce inventory and operating costs at nuclear power plants

  10. Multiplicity distributions in QCD cascades

    International Nuclear Information System (INIS)

    Gustafson, G.

    1992-03-01

    Multiplicity distributions for hadrons and for jets are studied in QCD parton cascades. The colour dipole formalism is used and earlier results in the double log approximation are generalized to include terms which are suppressed by colour factors or factors of ln s. The result is a set of coupled differential equations, together with appropriate boundary conditions

  11. Exchanges between the open Black Sea and its North West shelf

    Science.gov (United States)

    Shapiro, Georgy; Wobus, Fred; Zhou, Feng

    2014-05-01

    Exchanges between the vast NW shelf and the deep basin of the Black Sea play a significant role in maintaining the balance of nutrients, heat content and salinity of the shelf waters. Nearly 87 % of the Black Sea is entirely anoxic below 70 to 200m and contains high levels of hydrogen sulphide (Zaitsev et al, 2001), and this makes the shelf waters particularly valuable for maintaining the Black Sea ecosystem in good health. The increase in salinity of shelf waters occurs partially due to exchanges with more saline open sea waters and represents a threat to relics and endemic species. The shelf-break is commonly considered the bottle-neck of the shelf-deep sea exchanges (e.g. (Huthnance, 1995, Ivanov et al, 1997). Due to conservation of potential vorticity, the geostrophic currents flow along the contours of constant depth. However the ageostrophic flows (Ekman drift, mesoscale eddies, filaments, internal waves) are not subject to the same constraints. It has been shown that during the winter well mixed cold waters formed on the North West shelf propagate into the deep sea, providing an important mechanism for the replenishment of the Cold Intermediate Layer ( Staneva and Stanev, 1997). However, much less is known about exchanges in the warm season. In this study, the transports of water, heat and salt between the northwestern shelf and the adjacent deep basin of the Black Sea are investigated using a high-resolution three-dimensional primitive equation model, NEMO-SHELF-BLS (Shapiro et al, 2013). It is shown that during the period from April to August, 2005, both onshore and offshore cross-shelf break transports in the top 20 m were as high as 0.24 Sv on average, which was equivalent to the replacement of 60% of the volume of surface shelf waters (0 - 20 m) per month. Two main exchange mechanisms are studied: (i) Ekman transport, and (ii) transport by mesoscale eddies and associated meanders of the Rim Current. The Ekman drift causes nearly uniform onshore or

  12. A comparison of methods for cascade prediction

    OpenAIRE

    Guo, Ruocheng; Shakarian, Paulo

    2016-01-01

    Information cascades exist in a wide variety of platforms on Internet. A very important real-world problem is to identify which information cascades can go viral. A system addressing this problem can be used in a variety of applications including public health, marketing and counter-terrorism. As a cascade can be considered as compound of the social network and the time series. However, in related literature where methods for solving the cascade prediction problem were proposed, the experimen...

  13. Computer simulation of displacement cascades in copper

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1983-06-01

    More than 500 displacement cascades in copper have been generated with the computer simulation code MARLOWE over an energy range pertinent to both fission and fusion neutron spectra. Three-dimensional graphical depictions of selected cascades, as well as quantitative analysis of cascade shapes and sizes and defect densities, illustrate cascade behavior as a function of energy. With increasing energy, the transition from production of single compact damage regions to widely spaced multiple damage regions is clearly demonstrated

  14. The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations.

    Science.gov (United States)

    Guerrero, Raul A; Piola, Alberto R; Fenco, Harold; Matano, Ricardo P; Combes, Vincent; Chao, Yi; James, Corinne; Palma, Elbio D; Saraceno, Martin; Strub, P Ted

    2014-11-01

    Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. In spring and summer, low-salinity waters over the shelf expand offshore and are transferred to the open ocean primarily southeast of the river mouth (from 36°S to 37°30'S). In contrast, in fall and winter, low-salinity waters extend along a coastal plume and the export path to the open ocean distributes along the offshore edge of the plume. The strong seasonal SSS pattern is modulated by the seasonality of the along-shelf component of the wind stress over the shelf. However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that the precise location of the export of shelf waters depends on offshore circulation patterns, such as the location of the Brazil Malvinas Confluence and mesoscale eddies and meanders of the Brazil Current. The satellite data indicate that in summer, mixtures of low-salinity shelf waters are swiftly driven toward the ocean interior along the axis of the Brazil/Malvinas Confluence. In winter, episodic wind reversals force the low-salinity coastal plume offshore where they mix with tropical waters within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean. Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

  15. Dynamics robustness of cascading systems.

    Directory of Open Access Journals (Sweden)

    Jonathan T Young

    2017-03-01

    Full Text Available A most important property of biochemical systems is robustness. Static robustness, e.g., homeostasis, is the insensitivity of a state against perturbations, whereas dynamics robustness, e.g., homeorhesis, is the insensitivity of a dynamic process. In contrast to the extensively studied static robustness, dynamics robustness, i.e., how a system creates an invariant temporal profile against perturbations, is little explored despite transient dynamics being crucial for cellular fates and are reported to be robust experimentally. For example, the duration of a stimulus elicits different phenotypic responses, and signaling networks process and encode temporal information. Hence, robustness in time courses will be necessary for functional biochemical networks. Based on dynamical systems theory, we uncovered a general mechanism to achieve dynamics robustness. Using a three-stage linear signaling cascade as an example, we found that the temporal profiles and response duration post-stimulus is robust to perturbations against certain parameters. Then analyzing the linearized model, we elucidated the criteria of when signaling cascades will display dynamics robustness. We found that changes in the upstream modules are masked in the cascade, and that the response duration is mainly controlled by the rate-limiting module and organization of the cascade's kinetics. Specifically, we found two necessary conditions for dynamics robustness in signaling cascades: 1 Constraint on the rate-limiting process: The phosphatase activity in the perturbed module is not the slowest. 2 Constraints on the initial conditions: The kinase activity needs to be fast enough such that each module is saturated even with fast phosphatase activity and upstream changes are attenuated. We discussed the relevance of such robustness to several biological examples and the validity of the above conditions therein. Given the applicability of dynamics robustness to a variety of systems, it

  16. Connections between the growth of Arctica islandica and phytoplankton dynamics on the Faroe Shelf

    Science.gov (United States)

    Bonitz, Fabian; Andersson, Carin; Trofimova, Tamara

    2017-04-01

    In this study we use molluscan sclerochronological techniques in order to obtain closer insights into environmental and ecological dynamics of Faroe Shelf waters. The Faroe Shelf represents a special ecosystem with rich benthic and neritic communities, which also have great importance for many economically relevant fish stocks. Thus, a better understanding of seasonal and year-to-year phytoplankton and stratification dynamics would be useful because they also have implications for higher trophic levels. The water masses of the Faroe Shelf are fairly homogenous and isolated from off-shelf waters but at a certain depth, which is referred to as transition zone, seasonal stratification and horizontal exchange occur. Systematic observations and phytoplankton dynamic investigations have only been performed during the last 29 years but longer records are missing. Thus, we use the growth increment variability in long-lived Arctica islandica shells from the transition zone of the eastern Faroe Shelf to evaluate its potential to estimate on-shelf phytoplankton and stratification dynamics since previous studies have shown that the growth of A. islandica is highly dependent on food availability. We have built a shell-based master-chronology reaching back to the 17th century. Comparisons between the growth indices of our chronology and fluorescence data reveal significant positive relationships. In combination with an index that accounts for stratification even stronger correlations are obtained. This indicates that the growth of A. islandica is largely influenced by a combination of how much phytoplankton is produced and how much actually reaches the bottom, i.e. how well-mixed the water column is. Further significant positive correlations can also be found between the growth indices and other primary productivity data from the Faroe Shelf. In conclusion, our results suggest that the growth indices can be related to year-to-year changes in phytoplankton production and

  17. Surface and Subsurface Meltwater Ponding and Refreezing on the Bach Ice Shelf, Antarctic Peninsula

    Science.gov (United States)

    Willis, I.; Haggard, E.; Benedek, C. L.; MacAyeal, D. R.; Banwell, A. F.

    2017-12-01

    There is growing concern about the stability and fate of Antarctic ice shelves, as four major ice shelves on the Antarctic Peninsula have completely disintegrated since the 1950s. Their collapse has been linked to the southward movement of the -9 oC mean annual temperature isotherm. The proximal causes of ice shelf instability are not fully known, but an increase in surface melting leading to water ponding and ice flexure, fracture and calving has been implicated. Close to the recently collapsed Wilkins Ice Shelf, the Bach Ice Shelf (72°S 72°W) may be at risk from break up in the near future. Here, we document the changing surface hydrology of the Bach Ice Shelf between 2001 and 2017 using Landsat 7 & 8 imagery. Extensive surface water is identified across the Bach Ice Shelf and its tributary glaciers. Two types of drainage system are observed, drainage into firn via simple stream networks and drainage into the ocean via more complex networks. There are differences between the surface hydrology on the ice shelf and the tributary glaciers, as well as variations within and between summer seasons linked to surface air temperature fluctuations. We also document the changing subsurface hydrology of the ice shelf between 2014 and 2017 using Sentinel 1 A/B SAR imagery. Forty-five subsurface features are identified and analysed for their patterns and temporal evolution. Fourteen of the features show similar characteristics to previously-identified buried lakes and some occur in areas associated with surface lakes in previous years. The buried lakes show seasonal variability in area and surface backscatter, which varies with surface air temperature, and are consistent with the presence, enlargement and contraction of liquid water bodies. Buried lakes are an overlooked source of water loading on ice shelves, which may contribute to ice shelf flexure and potential fracture.

  18. Paleocene Wilcox cross-shelf channel-belt history and shelf-margin growth: Key to Gulf of Mexico sediment delivery

    Science.gov (United States)

    Zhang, Jinyu; Steel, Ronald; Ambrose, William

    2017-12-01

    Shelf margins prograde and aggrade by the incremental addition of deltaic sediments supplied from river channel belts and by stored shoreline sediment. This paper documents the shelf-edge trajectory and coeval channel belts for a segment of Paleocene Lower Wilcox Group in the northern Gulf of Mexico based on 400 wireline logs and 300 m of whole cores. By quantitatively analyzing these data and comparing them with global databases, we demonstrate how varying sediment supply impacted the Wilcox shelf-margin growth and deep-water sediment dispersal under greenhouse eustatic conditions. The coastal plain to marine topset and uppermost continental slope succession of the Lower Wilcox shelf-margin sediment prism is divided into eighteen high-frequency ( 300 ky duration) stratigraphic sequences, and further grouped into 5 sequence sets (labeled as A-E from bottom to top). Sequence Set A is dominantly muddy slope deposits. The shelf edge of Sequence Sets B and C prograded rapidly (> 10 km/Ma) and aggraded modestly ( 80 m/Ma) characterizes Sequence Sets D and E, which is associated with smaller (9-10 m thick on average) and isolated channel belts. This stratigraphic trend is likely due to an upward decreasing sediment supply indicated by the shelf-edge progradation rate and channel size, as well as an upward increasing shelf accommodation indicated by the shelf-edge aggradation rate. The rapid shelf-edge progradation and large rivers in Sequence Sets B and C confirm earlier suggestions that it was the early phase of Lower Wilcox dispersal that brought the largest deep-water sediment volumes into the Gulf of Mexico. Key factors in this Lower Wilcox stratigraphic trend are likely to have been a very high initial sediment flux to the Gulf because of the high initial release of sediment from Laramide catchments to the north and northwest, possibly aided by modest eustatic sea-level fall on the Texas shelf, which is suggested by the early, flat shelf-edge trajectory, high

  19. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  20. The effect of hydropower on fish stocks: comparison between cascade and non-cascade reservoirs

    Czech Academy of Sciences Publication Activity Database

    Draštík, Vladislav; Kubečka, Jan; Tušer, Michal; Čech, Martin; Frouzová, Jaroslava; Jarolím, Oldřich; Prchalová, Marie

    2008-01-01

    Roč. 609, č. 1 (2008), s. 25-36 ISSN 0018-8158. [EIFAC Symposium on hydropower , flood control and water abstraction: implications for fish and fisheries. Mondsee, 14.06.2006-17.06.2006] R&D Projects: GA ČR(CZ) GA206/06/1371; GA ČR(CZ) GA206/02/0520; GA ČR(CZ) GA206/07/1392; GA AV ČR(CZ) 1QS600170504 Institutional research plan: CEZ:AV0Z60170517 Keywords : abundance * biomass * longitudinal gradient * vertical and horizontal distribution * cascade Subject RIV: EH - Ecology, Behaviour Impact factor: 1.449, year: 2008

  1. Shelf life stability of lactobacilli encapsulated in raspberry powder: insights into non-dairy probiotics.

    Science.gov (United States)

    Anekella, Kartheek; Orsat, Valérie

    2014-06-01

    Study the shelf-life quality changes in raspberry juice with encapsulated lactobacilli (Lactobacillus rhamnosus NRRL B-4495 and Lactobacillus acidophilus NRRL B-442) obtained by spray drying and understand the various factors involved. Raspberry powder was obtained from spray drying lactobacilli and raspberry juice with maltodextrin as an additive. Shelf life of the powder was analyzed over a period of 30 d. Acid and bile tolerance and antibiotic resistance was compared before and after spray drying. Water activity, survival, and scanning electron microscope images were also measured during the shelf life. A combination of processing conditions: inlet temperature (°C), maltodextrin to juice solids ratio and inlet feed rate (ml/min) during spray drying had a significant role on the survival of lactobacilli during shelf life. Refrigerated storage provided a higher shelf-life stability with regards to CFU/g (as high as 84% on day 0 and 98% retention by the end of 30 d) compared to room temperature storage. Probiotic properties during shelf life are affected by the processing conditions and encapsulated food matrix. Thus, understanding these aspects in vitro during shelf life gives us a brief insight into the future of non-dairy probiotics.

  2. Flexural-response of the McMurdo Ice Shelf to surface lake filling and drainage

    Science.gov (United States)

    Banwell, A. F.; MacAyeal, D. R.; Willis, I.; Macdonald, G. J.; Goodsell, B.

    2017-12-01

    Antarctic ice-shelf instability and break-up, as exhibited by the Larsen B ice shelf in 2002, remains one of the most difficult glaciological processes to observe directly. It is, however, vital to do so because ice-shelf breakup has the potential to influence the buttressing controls on inland ice discharge, and thus to affect sea level. Several mechanisms enabling Larsen B style breakup have previously been proposed, including the ability of surface lakes to introduce ice-shelf fractures when they fill and drain. During the austral summer of 2016/2017, we monitored the filling and draining of four surface lakes on the McMurdo Ice Shelf, Antarctica, and the effect of these processes on ice-shelf flexure. Water-depth data from pressure sensors reveal that two lakes filled to >2 m in depth and subsequently drained over multiple week timescales, which had a simultaneous effect on vertical ice deflection in the area. Differential GPS data from 12 receivers over three months show that vertical deflection varies as a function of distance from the maximum load change (i.e. at the lake centre). Using remote sensing techniques applied to both Landsat 8 and Worldview imagery, we also quantify the meltwater volume in these two lakes through the melt season, which, together with the vertical deflection data, are used to constrain key flexural parameter values in numerical models of ice-shelf flexure.

  3. Geometric controls of the flexural gravity waves on the Ross Ice Shelf

    Science.gov (United States)

    Sergienko, O. V.

    2017-12-01

    Long-period ocean waves, formed locally or at distant sources, can reach sub-ice-shelf cavities and excite coupled motion in the cavity and the ice shelf - flexural gravity waves. Three-dimensional numerical simulations of the flexural gravity waves on the Ross Ice Shelf show that propagation of these waves is strongly controlled by the geometry of the system - the cavity shape, its water-column thickness and the ice-shelf thickness. The results of numerical simulations demonstrate that propagation of the waves is spatially organized in beams, whose orientation is determined by the direction of the of the open ocean waves incident on the ice-shelf front. As a result, depending on the beams orientation, parts of the Ross Ice Shelf experience significantly larger flexural stresses compared to other parts where the flexural gravity beams do not propagate. Very long-period waves can propagate farther away from the ice-shelf front exciting flexural stresses in the vicinity of the grounding line.

  4. Explicit representation and parametrised impacts of under ice shelf seas in the z∗ coordinate ocean model NEMO 3.6

    Directory of Open Access Journals (Sweden)

    P. Mathiot

    2017-07-01

    Full Text Available Ice-shelf–ocean interactions are a major source of freshwater on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean–sea ice model NEMO (Nucleus for European Modelling of the Ocean currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface, inclusion of open sub-ice-shelf cavities leads to a decrease in sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of high-salinity shelf water on the Ross and Weddell sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the overturning circulation under the ice shelves by introducing a prescribed meltwater flux over the depth range of the ice shelf base, rather than at the surface, is also assessed. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf to those from the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely used three equation ice shelf melting formulation, which enables an interactive computation of melting, is tested. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for the Amery, Getz and George VI ice shelves are considerably overestimated.

  5. Atom-atom collision cascades localization

    International Nuclear Information System (INIS)

    Kirsanov, V.V.

    1980-01-01

    The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

  6. Cascade Chaotic System With Applications.

    Science.gov (United States)

    Zhou, Yicong; Hua, Zhongyun; Pun, Chi-Man; Chen, C L Philip

    2015-09-01

    Chaotic maps are widely used in different applications. Motivated by the cascade structure in electronic circuits, this paper introduces a general chaotic framework called the cascade chaotic system (CCS). Using two 1-D chaotic maps as seed maps, CCS is able to generate a huge number of new chaotic maps. Examples and evaluations show the CCS's robustness. Compared with corresponding seed maps, newly generated chaotic maps are more unpredictable and have better chaotic performance, more parameters, and complex chaotic properties. To investigate applications of CCS, we introduce a pseudo-random number generator (PRNG) and a data encryption system using a chaotic map generated by CCS. Simulation and analysis demonstrate that the proposed PRNG has high quality of randomness and that the data encryption system is able to protect different types of data with a high-security level.

  7. Cascade reactor: granule fabrication processes

    International Nuclear Information System (INIS)

    Erlandson, O.D.; Winkler, E.O.; Maya, I.; Pitts, J.H.

    1985-01-01

    A key feature of Cascade is the granular blanket. Of the many blanket material options open to Cascade, fabrication of Li 2 O granules was felt to offer the greatest challenge. The authors explored available methods for initial Li 2 O granule fabrication. They identified three cost-effective processes for fabricating Li 2 O granules: the VSM drop-melt furnace process, which is based on melting and spheroidizing irregularly shaped Li 2 O feed granules; the LiOH process, which spheroidizes liquefied LiOH and uses GA Technologies' sphere-forming procedures; and the Li 2 CO 3 sol-gel process, used for making spherical fuel particles for the high-temperature gas-cooled reactor (HTGR). Each process is described below

  8. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  9. Experimental study of R134a/R410A cascade cycle for variable refrigerant flow heat pump systems

    International Nuclear Information System (INIS)

    Kim, Jeong Hun; Lee, Jae Wan; Park, Warn Gyu; Choi, Hwan Jong; Lee, Sang Hun; Oh, Sai Kee

    2015-01-01

    Cascade cycle is widely applied to heat pumps operating at low ambient temperature to overcome problems such as low heating capacity and Coefficient of performance (COP) deterioration A number of researches have been conducted on cascade cycle heat pumps, but most of those studies were focused on system optimization to determine optimal intermediate temperature in air-to-water heat pumps. However, experimental optimization in regard to air and water heating simultaneously using a cascade cycle has been an understudied area. Therefore, we focused on experimental analysis for a cascade system with Variable refrigerant flow (VRF) heat pumps. Experiments were conducted under a variety of operating conditions, such as ambient and water inlet temperature. COP increased up to 16% when water inlet temperature decreased. COP of VRF heat pumps with cascade cycle is three-times higher compared with conventional boilers as well as 17% higher compared to single heat pumps

  10. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  11. Dissolved inorganic nutrients and chlorophyll on the narrow continental shelf of Eastern Brazil

    Directory of Open Access Journals (Sweden)

    Gilmara Fernandes Eça

    2014-03-01

    Full Text Available The eastern Brazilian continental shelf is narrow and subject to the influence of a western boundary current system, presenting lower biological productivity than other regions. In this study, the distribution of water masses, dissolved inorganic nutrients, chlorophyll-a and total suspended solids (TSS on the inner shelf (< 35 m depth, between Itacaré and Canavieiras, eastern Brazil, is presented. Sampling surveys were carried out in March and August 2006 and March 2007. Tropical water (TW prevailed during March 2006 and August 2007 with the lower salinity waters (< 36 found in most samples taken in March 2007, reflecting the influence of continental outflow and rain in coastal waters. Low concentrations of dissolved inorganic nutrients and Chl-a found were typical of TW and results suggested that the inner shelf waters were depleted in dissolved inorganic nitrogen in August 2006 and March 2007, and in phosphate in March 2006, potentially affecting phytoplankton growth. Stratification of the water column was observed due to differences in dissolved nutrient concentrations, chlorophyll-a and TSS when comparing surface and bottom samples, possibly the result of a colder water intrusion and mixing on the bottom shelf and a deep chlorophyll maximum and/or sediment resuspension effect. Despite this stratification, oceanographic processes such as lateral mixing driven by the Brazil Current as well as a northward alongshore drift driven by winds and tides transporting Coastal Water can lead to an enhanced mixing of these waters promoting some heterogeneity in this oligotrophic environment.

  12. The evolution of a coupled ice shelf-ocean system under different climate states

    Science.gov (United States)

    Grosfeld, Klaus; Sandhäger, Henner

    2004-07-01

    Based on a new approach for coupled applications of an ice shelf model and an ocean general circulation model, we investigate the evolution of an ice shelf-ocean system and its sensitivity to changed climatic boundary conditions. Combining established 3D models into a coupled model system enabled us to study the reaction and feedbacks of each component to changes at their interface, the ice shelf base. After calculating the dynamics for prescribed initial ice shelf and bathymetric geometries, the basal mass balance determines the system evolution. In order to explore possible developments for given boundary conditions, an idealized geometry has been chosen, reflecting basic features of the Filchner-Ronne Ice Shelf, Antarctica. The model system is found to be especially sensitive in regions where high ablation or accretion rates occur. Ice Shelf Water formation as well as the build up of a marine ice body, resulting from accretion of marine ice, is simulated, indicating strong interaction processes. To improve consistency between modeled and observed ice shelf behavior, we incorporate the typical cycle of steady ice front advance and sudden retreat due to tabular iceberg calving in our time-dependent simulations. Our basic hypothesis is that iceberg break off is associated with abrupt crack propagation along elongated anomalies of the inherent stress field of the ice body. This new concept yields glaciologically plausible results and represents an auspicious basis for the development of a thorough calving criterion. Experiments under different climatic conditions (ocean warming of 0.2 and 0.5 °C and doubled surface accumulation rates) show the coupled model system to be sensitive especially to ocean warming. Increased basal melt rates of 100% for the 0.5 °C ocean warming scenario and an asymmetric development of ice shelf thicknesses suggest a high vulnerability of ice shelf regions, which represent pivotal areas between the Antarctic Ice Sheet and the Southern

  13. Nutrient regeneration and oxygen demand in Bering Sea continental shelf sediments

    Science.gov (United States)

    Rowe, Gilbert T.; Phoel, William C.

    1992-04-01

    Measurements of seabed oxygen demand and nutrient regeneration were made on continental shelf sediments in the southeast Bering Sea from 1 to 15 June 1981. The mean seabed oxygen demand was relatively modest (267 μM O 2 m -2 h -1), equivalent to a utilization of 60 mg organic carbon m -2 day -1. The seasonal build up of ammonium over the mid-shelf domain was generated at least in part by the bottom biota, as previously suggested ( WHITLEDGEet al., 1986 , Continental Shelf Research, 5, 109-132), but on the outer shelf nitrate replaced ammonium as the dominant inorganic nitrogen compound that was regenerated from the sediments. Comparison of oxygen consumption with the organic matter in sedimenting particulate matter (sampled with sediment traps) could imply that benthic processes were not accounting for the fate of considerable quantities of organic matter. Benthic oxygen demand rates, however, probably lag behind the input of the spring bloom to the bottom, thus extending the remineralization process out over time. Consumption by small microheterotrophs in the water column was also a likely sink, although shelf export and advective transport north were possible as well. Estimated nitrification rates in surface sediments could account for only a small fraction of the abrupt increase in nitrate observed in the water column over the shelf just prior to the spring bloom.

  14. West Florida shelf circulation and temperature budget for the 1998 fall transition

    Science.gov (United States)

    He, Ruoying; Weisberg, Robert H.

    2003-05-01

    Mid-latitude continental shelves undergo a fall transition as the net heat flux changes from warming to cooling. Using in situ data and a numerical model we investigate the circulation on the west Florida shelf (WFS) for the fall transition of 1998. The model is a regional adaptation of the primitive equation, Princeton Ocean Model forced by NCEP reanalysis wind, air pressure, and heat flux fields, plus river inflows. After comparison with observations the model is used to draw inferences on the seasonal and synoptic scale features of the shelf circulation. By running twin experiments, one without and the other with an idealized Loop Current (LC), we explore the relative importance of local versus deep-ocean forcing. We find that local forcing largely controls the inner-shelf circulation, including changes from the Florida Panhandle in the north to regions farther south. The effects of the LC in fall 1998 are to reinforce the mid-shelf currents and to increase the across-shelf transports in the bottom Ekman layer, thereby accentuating the shoreward transport of cold, nutrient rich water of deep-ocean origin. A three-dimensional analysis of the temperature budget reveals that surface heat flux largely controls both the seasonal and synoptic scale temperature variations. Surface cooling leads to convective mixing that rapidly alters temperature gradients. One interesting consequence is that upwelling can result in near-shore warming as warmer offshore waters are advected landward. The temperature balances on the shelf are complex and fully three-dimensional.

  15. Ocean stratification reduces melt rates at the grounding zone of the Ross Ice Shelf

    Science.gov (United States)

    Begeman, C. B.; Tulaczyk, S. M.; Marsh, O.; Mikucki, J.; Stanton, T. P.; Hodson, T. O.; Siegfried, M. R.; Powell, R. D.; Christianson, K. A.; King, M. A.

    2017-12-01

    Ocean-driven melting of ice shelves is often invoked as the primary mechanism for triggering ice loss from Antarctica. However, due to the difficulty in accessing the sub-ice-shelf ocean cavity, the relationship between ice-shelf melt rates and ocean conditions is poorly understood, particularly near the transition from grounded to floating ice, known as the grounding zone. Here we present the first borehole oceanographic observations from the grounding zone of Antarctica's largest ice shelf. Contrary to predictions that tidal currents near grounding zones should mix the water column, driving high ice-shelf melt rates, we find a stratified sub-ice-shelf water column. The vertical salinity gradient dominates stratification over a weakly unstable vertical temperature gradient; thus, stratification takes the form of a double-diffusive staircase. These conditions limit vertical heat fluxes and lead to low melt rates in the ice-shelf grounding zone. While modern grounding zone melt rates may presently be overestimated in models that assume efficient tidal mixing, the high sensitivity of double-diffusive staircases to ocean freshening and warming suggests future melt rates may be underestimated, biasing projections of global sea-level rise.

  16. Plankton community respiration, net ecosystem metabolism, and oxygen dynamics on the Louisiana continental shelf: implications for hypoxia

    Science.gov (United States)

    We conducted a multi-year study of the Louisiana continental shelf (LCS) to better understand the linkages between water column metabolism and the formation of hypoxia (dissolved oxygen respiration rates (WR) were measured on 10 cr...

  17. 77 FR 10711 - Safety Zone; KULLUK, Outer Continental Shelf Mobile Offshore Drilling Unit (MODU), Beaufort Sea, AK

    Science.gov (United States)

    2012-02-23

    ... environment given the sensitivity of the environmental and subsistence importance to the indigenous population... Shelf and its distance from both land and safety fairways. Vessels traversing waters near the proposed...

  18. Modern shelf ice, equatorial Aeolis Quadrangle, Mars

    Science.gov (United States)

    Brakenridge, G. R.

    1993-01-01

    As part of a detailed study of the geological and geomorphological evolution of Aeolis Quadrangle, I have encountered evidence suggesting that near surface ice exists at low latitudes and was formed by partial or complete freezing of an inland sea. The area of interest is centered at approximately -2 deg, 196 deg. As seen in a suite of Viking Orbiter frames obtained at a range of approximately 600 km, the plains surface at this location is very lightly cratered or uncratered, and it is thus of late Amazonian age. Extant topographic data indicate that the Amazonian plains at this location occupy a trough whose surface lies at least 1000 m below the Mars datum. A reasonable hypothesis is that quite recent surface water releases, perhaps associated with final evolution of large 'outflow chasms' to the south, but possibly from other source areas, filled this trough, that ice floes formed almost immediately, and that either grounded ice or an ice-covered sea still persists. A reasonable hypothesis is that quite recent surface water releases, perhaps associated with final evolution of large 'outflow chasms' to the south, but possibly from other source areas, filled this trough, that ice floes formed almost immediately, and that either grounded ice or an ice-covered sea still persists. In either case, the thin (a few meters at most) high albedo, low thermal inertia cover of aeolian materials was instrumental in allowing ice preservation, and at least the lower portions of this dust cover may be cemented by water ice. Detailed mapping using Viking stereopairs and quantitative comparisons to terrestrial shelf ice geometries are underway.

  19. Impacts of Suspended Sediment and Estuarine - Shelf Exchange Pathways on Shelf Ecosystem Dynamics in the Northern Gulf of Mexico

    Science.gov (United States)

    Wiggert, J. D.; Pan, C.; Dinniman, M. S.; Lau, Y.; Fitzpatrick, P. J.; O'Brien, S. J.; Bouchard, C.; Quas, L. M.; Miles, T. N.; Cambazoglu, M. K.; Dykstra, S. L.; Dzwonkowski, B.; Jacobs, G. A.; Church, I.; Hofmann, E. E.

    2017-12-01

    A circulation model based on the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System, with coupled biogeochemical and sediment transport modules, has been implemented for Mississippi Sound and the adjacent continental shelf region. The model has 400-m horizontal resolution, 24 vertical layers, and includes wetting/drying capability to resolve shallow inshore regions. The circulation model was spun-up using oceanographic initial and lateral boundary conditions provided by a 1-km resolution regional implementation of the Navy Coastal Ocean Model (NCOM) in the Gulf of Mexico. The biogeochemical module includes multiple size classes of phytoplankton, zooplankton and detritus, a fish larvae compartment, and explicitly tracks dissolved oxygen with benthic cycling interaction. The sediment transport model is implemented based on benthic mapping data that provides bottom sediment type distributions and spatio-temporal validation. A regionally specific atmospheric forcing product that provides improved spatial and temporal resolution, including diurnal sea breeze impacts, has been developed and applied. Model experiments focus on periods when comprehensive ship-based sampling was deployed by the CONCORDE (Consortium for Coastal River-Dominated Ecosystems) research program, which was established to investigate the complex fine-scale biological, chemical and physical interactions in a marine system controlled by pulsed-river plume dynamics. Biophysical interactions and biogeochemical variability associated with estuarine - shelf exchanges between nearshore lagoonal estuarine waters and the continental shelf revealed by the model provide new insight into how seasonal variation of hydrological forcing conditions influence ecological and biogeochemical processes in the highly productive Northern Gulf region. Application of the COAWST-based model system with and without inclusion of the sediment transport module demonstrates how suspended sediment in the

  20. Effects of energy-related activities on the Atlantic Continental Shelf

    Energy Technology Data Exchange (ETDEWEB)

    Manowitz, B [ed.

    1975-01-01

    Sixteen papers were presented and are announced separately. Coastal waters, continental shelf geology and aquatic ecosystems are studied for modelling basic data for assessment of possible environmental impacts from offshore energy development. Sediment transport and wave phenomena are modelled for understanding water pollution transport and diffusion. (PCS)

  1. Uranium geochemistry on the Amazon shelf: Evidence for uranium release from bottom sediments

    International Nuclear Information System (INIS)

    McKee, B.A.; DeMaster, D.J.; Nittrouer, C.A.

    1987-01-01

    In Amazon-shelf waters, as salinity increases to 36.5 x 10 -3 , dissolved uranium activities increase to a maximum of 4.60 dpm 1 -1 . This value is much higher than the open-ocean value (2.50 dpm 1 -1 ), indicating a source of dissolved uranium to shelf waters in addition to that supplied from open-ocean and riverine waters. Uranium activities are much lower for surface sediments in the Amazon-shelf sea bed (mean: 0.69 ± .09 dpm g -1 ) than for suspended sediments in the Amazon river (1.82 dpm g -1 ). Data suggest that the loss of particulate uranium from riverine sediments is probably the result of uranium desorption from the ferric-oxyhydroxide coatings on sediment particles, and/or uranium release by mobilization of the ferric oxyhydroxides. The total flux of dissolved 238 U from the Amazon shelf (about 1.2 x 10 15 dpm yr -1 ) constitutes about 15% of uranium input to the world ocean, commensurate to the Amazon River's contribution to world river-water discharge. Measurement of only the riverine flux of dissolved 238 U underestimates, by a factor of about 5, the flux of dissolved 238 U from the Amazon shelf to the open ocean

  2. Cryolithozone of Western Arctic shelf of Russia

    Science.gov (United States)

    Kholmyanskii, Mikhail; Vladimirov, Maksim; Snopova, Ekaterina; Kartashev, Aleksandr

    2017-04-01

    We propose a new original version of the structure of the cryolithozone of west Arctic seas of Russia. In contrast to variants of construction of sections and maps based on thermodynamic modeling, the authors have used electrometric, seismic, and thermal data including their own profile measurements by near-field transient electromagnetic technique and seismic profile observations by reflection method. As a result, we defined the spatial characteristics of cryolithozone and managed to differentiate it to several layers, different both in structure and formation time. We confirmed once again that the spatial boundary of cryolithozone, type and thickness of permafrost, chilled rocks and thawed ground are primarily determined by tectonic and oceanographic regimes of the Arctic Ocean and adjacent land in different geological epochs. Permafrost formed on the land in times of cold weather, turn to submarine during flooding and overlap, in the case of the sea transgression, by marine sediments accumulating in the period of warming. We have been able to establish a clear link between the permafrost thickness and the geomorphological structure of the area. This can be explained by the distribution of thermodynamic flows that change the temperature state of previously formed permafrost rocks. Formation in the outer parts of the shelf which took place at ancient conversion stage can be characterized by the structure: • permafrost table - consists of rocks, where the sea water with a temperature below 0 °C has replaced the melted ice; • middle horizon - composed of undisturbed rocks, and the rocks chilled through the lower sieving underlay; As a result of the interpretation and analysis of all the available data, the authors created a map of types of cryolithozone of the Western Arctic shelf of Russia. The following distribution areas are marked on the map: • single-layer cryolithozone (composed of sediments upper Pleistocene and Holocene); • monosyllabic relict

  3. Abnormal cascading failure spreading on complex networks

    International Nuclear Information System (INIS)

    Wang, Jianwei; Sun, Enhui; Xu, Bo; Li, Peng; Ni, Chengzhang

    2016-01-01

    Applying the mechanism of the preferential selection of the flow destination, we develop a new method to quantify the initial load on an edge, of which the flow is transported along the path with the shortest edge weight between two nodes. Considering the node weight, we propose a cascading model on the edge and investigate cascading dynamics induced by the removal of the edge with the largest load. We perform simulated attacks on four types of constructed networks and two actual networks and observe an interesting and counterintuitive phenomenon of the cascading spreading, i.e., gradually improving the capacity of nodes does not lead to the monotonous increase in the robustness of these networks against cascading failures. The non monotonous behavior of cascading dynamics is well explained by the analysis on a simple graph. We additionally study the effect of the parameter of the node weight on cascading dynamics and evaluate the network robustness by a new metric.

  4. Aplicação do diagrama T-S estatístico: volumétrico à análise das massas de água da plataforma continental do Rio Grande do Sul The statistical volumetric T-S diagram applied to the analysis of water masses of Rio Grande do Sul continental shelf

    Directory of Open Access Journals (Sweden)

    Luiz Bruner de Miranda

    1979-06-01

    Full Text Available The general characteristics of the seasonal variation of the thermohaline properties of the continental shelf water off Rio Grande do Sul, under non-conservative and quasi-synoptic conditions were analysed. The method applied - volumetric statistical T-S analysis allows the computation of the water masses budget from the knowledge of their temperature and salinity ranges. The data of 194 hydrographic stations from six oceanographic cruises between April 1968 and March 1969, were used. Water of Tropical and Subtropical origin (47,5% and 64% of the total volume during the winter and summer, respectively was always present during the observation period. Subantarctic water has its maximum and minimum influences during the winter (15% and summer (<3%, respectively. The average minimum and maximum temperature and salinity values of the water masses in the investigated region were observed in June (16,85ºC and 34,72‰, December (35,58‰ and March (20,82ºC.

  5. Groundwater quality in the Cascade Range and Modoc Plateau, California

    Science.gov (United States)

    Fram, Miranda S.; Shelton, Jennifer L.

    2015-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The Cascade Range and Modoc Plateau area constitutes one of the study units being evaluated.

  6. The width of electron-photon cascades in air

    International Nuclear Information System (INIS)

    Allan, H.R.; Crannell, C.J.; Hough, J.H.; Shutie, P.F.; Sun, M.P.

    1975-01-01

    A new Monte-Carlo simulation of electron-photon cascade development is shown to give results in agreement with a) the calculations of Nordheim et al, b) simulations using the Berger-Seltzer electron photon transport programme and c) experimental measurements in water. However, the lateral spread is much narrower than that given by the Nishimura-Kamata functions or the Messel-Crawford tabulations. (orig.) [de

  7. Disaster Mythology and Availability Cascades

    Directory of Open Access Journals (Sweden)

    Lisa Grow Sun

    2013-04-01

    Full Text Available Sociological research conducted in the aftermath of natural disasters has uncovered a number of “disaster myths” – widely shared misconceptions about typical post-disaster human behavior. This paper discusses the possibility that perpetuation of disaster mythology reflects an “availability cascade,” defined in prior scholarship as a “self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse.” (Kuran and Sunstein 1999. Framing the spread of disaster mythology as an availability cascade suggests that certain tools may be useful in halting the myths’ continued perpetuation. These tools include changing the legal and social incentives of so-called “availability entrepreneurs” – those principally responsible for beginning and perpetuating the cascade, as well as insulating decision-makers from political pressures generated by the availability cascade. This paper evaluates the potential effectiveness of these and other solutions for countering disaster mythology. Las investigaciones sociológicas realizadas tras los desastres naturales han hecho evidentes una serie de “mitos del desastre”, conceptos erróneos ampliamente compartidos sobre el comportamiento humano típico tras un desastre. Este artículo analiza la posibilidad de que la perpetuación de los mitos del desastre refleje una “cascada de disponibilidad”, definida en estudios anteriores como un “proceso de auto-refuerzo de la formación de una creencia colectiva, a través del que una percepción expresada produce una reacción en cadena que hace que la percepción sea cada vez más verosímil, a través de una mayor presencia en el discurso público” (Kuran y Sunstein 1999. Enmarcar la propagación de los mitos del desastre como una cascada de disponibilidad sugiere que ciertas herramientas pueden ser

  8. Ion-implantation dense cascade data

    International Nuclear Information System (INIS)

    Winterbon, K.B.

    1983-04-01

    A tabulation is given of data useful in estimating various aspects of ion-implantation cascades in the nuclear stopping regime, particularly with respect to nonlinearity of the cascade at high energy densities. The tabulation is restricted to self-ion implantation. Besides power-cross-section cascade dimensions, various material properties are included. Scaling of derived quantities with input data is noted, so one is not limited to the values assumed by the author

  9. Influence of estuaries on shelf foraminiferal species

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    Dabhol-bhatkal stretch of the west coast of India is marked by a number of estuaries. Cavarotalia annectens is selected to monitor the influence of these estuaries on the inner shelf foraminiferal fauna. The percentage distribution of this species...

  10. Southwest Florida Shelf Ecosystems Analysis Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Southwest Florida Shelf Ecosystems Analysis Study produced grain size analyses in the historic 073 format for 299 sea floor samples collected from October 25,...

  11. The shelf life of dyed polymethylmethacrylate dosimeters

    International Nuclear Information System (INIS)

    Bett, R.; Watts, M.F.; Plested, M.E.

    2002-01-01

    The long-term stability of the radiation response of Harwell Red 4034 and Amber 3042 Perspex Dosimeters has been monitored for more than 15 years, and the resulting data used in the justification of their shelf-life specifications

  12. Tidal Mixing at the Shelf Break

    National Research Council Canada - National Science Library

    Hogg, Nelson; Legg, Sonya

    2005-01-01

    The aim of this project was to study mixing forced by tidal flow over sudden changes in topographic slope such as near the shelf-break, using high-resolution nonhydrostatic numerical simulations employing the MIT gem...

  13. A non-conventional isotope separation cascade without any mixing: net cascade

    International Nuclear Information System (INIS)

    Zeng Shi; Jiang Dongjun; Ying Zhengen

    2012-01-01

    A component has different concentrations in the incoming flows at a confluent point in all existing isotope separations cascades for multi-component isotope separation and mixing is inevitable, which results in deterioration of separation performance of the separation cascade. However, realization of no-mixing at a confluent point is impossible with a conventional cascade. A non-conventional isotope separation cascade, net cascade, is found to be able to realize no mixings for all components at confluent points, and its concept is further developed here. No-mixing is fulfilled by requiring symmetrical separation of two specified key components at every stage, and the procedure of realizing no-mixing is presented in detail. Some properties of net cascade are investigated preliminarily, and the results demonstrated the no-mixing property is indeed realized. Net cascade is the only separation cascade that so far possesses the no-mixing property. (authors)

  14. Evolution of Meltwater on the McMurdo Ice Shelf, Antarctica During Two Summer Melt Seasons

    Science.gov (United States)

    Macdonald, G. J.; Banwell, A. F.; Willis, I.; Mayer, D. P.; Hansen, E. K.; MacAyeal, D. R.

    2017-12-01

    Ice shelves surround > 50% of Antarctica's coast and their response to climate change is key to the ice sheet's future and global sea-level rise. Observations of the development and drainage of 2750 lakes prior to the collapse of the Larsen B Ice Shelf, combined with our understanding of ice-shelf flexure/fracture, suggest that surface meltwater plays a key role in ice-shelf stability, although the present state of knowledge remains limited. Here, we report results of an investigation into the seasonal evolution of meltwater on the McMurdo Ice Shelf (MIS) during the 2015/16 and 2016/17 austral summers using satellite remote sensing, complemented by ground survey. Although the MIS is relatively far south (78° S), it experiences relatively high ablation rates in the west due to adiabatically warmed winds, making it a useful example of how meltwater could evolve on more southerly ice shelves in a warming climate. We calculate the areas and depths of ponded surface meltwater on the ice shelf at different stages of the two melt seasons using a modified NDWI approach and water-depth algorithm applied to both Landsat 8 and Worldview imagery. Data from two automatic weather stations on the ice shelf are used to drive a positive degree-day model to compare our observations of surface water volumes with modelled meltwater production. Results suggest that the spatial and temporal variations in surface meltwater coverage on the ice shelf vary not only with climatic conditions but also in response to other important processes. First, a rift that widens and propagates between the two melt seasons intercepts meltwater streams, redirecting flow and facilitating ponding elsewhere. Second, some lakes from previous years remain frozen over and become pedestalled, causing streams to divert around their perimeter. Third, surface debris conditions also cause large-scale spatial variation in melt rates and the flow and storage of water.

  15. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  16. Radurisation of broilers for shelf life extension

    International Nuclear Information System (INIS)

    Bok, H.E.; Holzapfel, W.H.; Van der Linde, H.J.

    1982-01-01

    Radurization is discussed as a method for the shelf life extension of refrigerated chicken carcasses. One of the advantages is that radurization eliminates potential food pathogenic bacteria like Salmonella in the chicken carcasses. Materials and methods for the radurization of chicken are discussed. The objective of the investigation was to determine the influence of different irradiation doses and storage conditions on the microbiological shelf life and organoleptic quality of fresh broilers

  17. How ice shelf morphology controls basal melting

    Science.gov (United States)

    Little, Christopher M.; Gnanadesikan, Anand; Oppenheimer, Michael

    2009-12-01

    The response of ice shelf basal melting to climate is a function of ocean temperature, circulation, and mixing in the open ocean and the coupling of this external forcing to the sub-ice shelf circulation. Because slope strongly influences the properties of buoyancy-driven flow near the ice shelf base, ice shelf morphology plays a critical role in linking external, subsurface heat sources to the ice. In this paper, the slope-driven dynamic control of local and area-integrated melting rates is examined under a wide range of ocean temperatures and ice shelf shapes, with an emphasis on smaller, steeper ice shelves. A 3-D numerical ocean model is used to simulate the circulation underneath five idealized ice shelves, forced with subsurface ocean temperatures ranging from -2.0°C to 1.5°C. In the sub-ice shelf mixed layer, three spatially distinct dynamic regimes are present. Entrainment of heat occurs predominately under deeper sections of the ice shelf; local and area-integrated melting rates are most sensitive to changes in slope in this "initiation" region. Some entrained heat is advected upslope and used to melt ice in the "maintenance" region; however, flow convergence in the "outflow" region limits heat loss in flatter portions of the ice shelf. Heat flux to the ice exhibits (1) a spatially nonuniform, superlinear dependence on slope and (2) a shape- and temperature-dependent, internally controlled efficiency. Because the efficiency of heat flux through the mixed layer decreases with increasing ocean temperature, numerical simulations diverge from a simple quadratic scaling law.

  18. Circulation in the SAV, Shelf of Veracruz, Mexico

    Science.gov (United States)

    Zavala-Hidalgo, J.; Martinez-Lopez, B.; Fernandez-Eguiarte, A.; de Buen, R.; Rojas, J.

    2007-05-01

    Data from current meter, hydrographic measurements, and numerical modeling are analyzed to determine the circulation patterns in the Sistema Arrecifal Veracruzano (SAV), Veracruz, Mexico, region. Results show that the main forcing in the region is the along-coast wind stress component. Tides contribute with one order of magnitude less energy, during the fall-winter period. Two main regimes are identified: one between the coast and the 20 m isobath, with waters of large turbidity and small influence from rivers, and the other between the 20 m isobath and the external shelf, with clearer waters. Stratified water column with low temperature upwelled waters near the bottom are observed when southeasterly winds are present. Downwelling and southeastward currents are associated with northerly winds linked with northers.

  19. Antarctic Ice Shelf Potentially Stabilized by Export of Meltwater in Surface River

    Science.gov (United States)

    Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

    2017-01-01

    Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks-interconnected streams, ponds and rivers-on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf's meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica-contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

  20. Mixing processes at the subsurface layer in the Amundsen Sea shelf region

    Science.gov (United States)

    Mojica, J.; Djoumna, G.; Francis, D. K.; Holland, D.

    2017-12-01

    In the Amundsen Sea shelf region, mixing processes promote an upward transport of diapycnal fluxes of heat and salt from the subsurface to the surface mixing layer. Here we estimate the diapycnal mixing rates on the Amundsen shelf from a multi-year mooring cluster and five research cruises. By applying fine-scale parameterizations, the mixing rates obtained were higher near the southern end of Pine Island glacier front and exceeded 10-2 m2s-1. The eddy diffusivity increased near the critical latitude (74o 28' S) for semi-diurnal M2 tides, which coincided with near-critical topography on the shelf. This condition favored the generation of internal waves of M2 frequency. The semi-diurnal dynamic enhanced the mixing that potentially affected the heat budget and the circulation of the modified Circumpolar Deep Water. This can be observed in the characteristics of water exchange both below the ice shelves and between the continental shelf and the ice shelf cavities. The location of the critical latitude and critical topography provided favorable conditions for the generation of internal waves. KEYWORDS: Mixing processes, diapycnal fluxes, critical latitude, Circumpolar Deep Water.

  1. Evaluating Current Practices in Shelf Life Estimation.

    Science.gov (United States)

    Capen, Robert; Christopher, David; Forenzo, Patrick; Huynh-Ba, Kim; LeBlond, David; Liu, Oscar; O'Neill, John; Patterson, Nate; Quinlan, Michelle; Rajagopalan, Radhika; Schwenke, James; Stroup, Walter

    2018-02-01

    The current International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) methods for determining the supported shelf life of a drug product, described in ICH guidance documents Q1A and Q1E, are evaluated in this paper. To support this evaluation, an industry data set is used which is comprised of 26 individual stability batches of a common drug product where most batches are measured over a 24 month storage period. Using randomly sampled sets of 3 or 6 batches from the industry data set, the current ICH methods are assessed from three perspectives. First, the distributional properties of the supported shelf lives are summarized and compared to the distributional properties of the true shelf lives associated with the industry data set, assuming the industry data set represents a finite population of drug product batches for discussion purposes. Second, the results of the ICH "poolability" tests for model selection are summarized and the separate shelf life distributions from the possible alternative models are compared. Finally, the ICH methods are evaluated in terms of their ability to manage risk. Shelf life estimates that are too long result in an unacceptable percentage of nonconforming batches at expiry while those that are too short put the manufacturer at risk of possibly having to prematurely discard safe and efficacious drug product. Based on the analysis of the industry data set, the ICH-recommended approach did not produce supported shelf lives that effectively managed risk. Alternative approaches are required.

  2. A Semisupervised Cascade Classification Algorithm

    Directory of Open Access Journals (Sweden)

    Stamatis Karlos

    2016-01-01

    Full Text Available Classification is one of the most important tasks of data mining techniques, which have been adopted by several modern applications. The shortage of enough labeled data in the majority of these applications has shifted the interest towards using semisupervised methods. Under such schemes, the use of collected unlabeled data combined with a clearly smaller set of labeled examples leads to similar or even better classification accuracy against supervised algorithms, which use labeled examples exclusively during the training phase. A novel approach for increasing semisupervised classification using Cascade Classifier technique is presented in this paper. The main characteristic of Cascade Classifier strategy is the use of a base classifier for increasing the feature space by adding either the predicted class or the probability class distribution of the initial data. The classifier of the second level is supplied with the new dataset and extracts the decision for each instance. In this work, a self-trained NB∇C4.5 classifier algorithm is presented, which combines the characteristics of Naive Bayes as a base classifier and the speed of C4.5 for final classification. We performed an in-depth comparison with other well-known semisupervised classification methods on standard benchmark datasets and we finally reached to the point that the presented technique has better accuracy in most cases.

  3. Honeywell Cascade Distiller System Performance Testing Interim Results

    Science.gov (United States)

    Callahan, Michael R.; Sargusingh, Miriam

    2014-01-01

    The ability to recover and purify water through physiochemical processes is crucial for realizing long-term human space missions, including both planetary habitation and space travel. Because of their robust nature, distillation systems have been actively pursued as one of the technologies for water recovery. The Cascade Distillation System (CDS) is a vacuum rotary distillation system with potential for greater reliability and lower energy costs than existing distillation systems. The CDS was previously under development through Honeywell and NASA. In 2009, an assessment was performed to collect data to support down-selection and development of a primary distillation technology for application in a lunar outpost water recovery system. Based on the results of this testing, an expert panel concluded that the CDS showed adequate development maturity, TRL-4, together with the best product water quality and competitive weight and power estimates to warrant further development. The Advanced Exploration Systems (AES) Water Recovery Project (WRP) worked to address weaknesses identified by The Panel; namely bearing design and heat pump power efficiency. Testing at the NASA-JSC Advanced Exploration System Water Laboratory (AES Water Lab) using a prototype Cascade Distillation Subsystem (CDS) wastewater processor (Honeywell International, Torrance, Calif.) with test support equipment and control system developed by Johnson Space Center was performed to evaluate performance of the system with the upgrades. The CDS will also have been challenged with ISS analog waste streams and a subset of those being considered for Exploration architectures. This paper details interim results of the AES WRP CDS performance testing.

  4. Influence of oceanographic features on the spatial and seasonal patterns of mesozooplankton in the southern Patagonian shelf (Argentina, SW Atlantic)

    Science.gov (United States)

    Sabatini, M. E.; Reta, R.; Lutz, V. A.; Segura, V.; Daponte, C.

    2016-05-01

    Surveys conducted during spring, summer and late winter in 2005-2006 over the southern Patagonian shelf have allowed the seasonal distribution of mesozooplankton communities in relation to water masses and circulation to be investigated. In this system, most of the shelf is dominated by a distinct low salinity plume that is related to the runoff from the Magellan Strait (MSW), while the outer shelf is highly influenced by the cold and salty Subantarctic water (SAW) of the boundary Malvinas Current. Separating these two, the Subantarctic Shelf water mass (SASW) extends over the middle shelf. Correspondingly, the structure of the MSW and SAW mesozooplankton communities was found to be clearly different, while the former and the SASW assemblages were barely separable. This relatively fresh water mass is actually a variant of Subantarctic water that enters into the region from the south and the shelf-break, and hence its mesozooplankton community was not significantly different from that of the SAW water mass. Dissimilar species abundance, in turn associated with different life histories and population development, was more important than species composition in defining the assemblages. Total mesozooplankton abundance increased about 2.5-fold from the beginning of spring to late summer, and then decreased at least two orders of magnitude in winter. Across all seasons copepods represented > 70-80% of total mesozooplankton over most of the shelf. Copepod species best represented through all seasons, in terms of both relative abundance and occurrence, were Drepanopus forcipatus and Oithona helgolandica. Although seasonal differences in abundance were striking, the spatial distribution of mesozooplankton was largely similar across seasons, with relatively higher concentrations occurring mainly in Grande Bay and surroundings. The well defined spatial patterns of mesozooplankton that appear from our results in conjunction with the southward wide extension of the shelf and

  5. 41 CFR 101-27.205 - Shelf-life codes.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Shelf-life codes. 101-27...-Management of Shelf-Life Materials § 101-27.205 Shelf-life codes. Shelf-life items shall be identified by use of a one-digit code to provide for uniform coding of shelf-life materials by all agencies. (a) The...

  6. Dynamics of internal waves on the Southeast Florida shelf: Implications for cross-shelf exchange and turbulent mixing on a barrier reef system

    Science.gov (United States)

    Davis, Kristen Alexis

    The dynamics of internal waves shoaling on the Southeast Florida shelf and the resulting stratified turbulence in the shelf bottom boundary layer are investigated using observational studies completed during the summers of 2003-2005. This work is driven by a desire to understand the effects of internal wave-driven flow and the shoreward transport of cool, nutrient-rich water masses on cross-shelf exchange, vertical mixing, and mass transfer to benthic reef organisms. Shelf sea internal wave fields are typically highly variable and dominated by wind and tidal forces. However, this is not necessarily true for outer shelf regions or very narrow shelves where remote physical processes originating over the slope or deep ocean may exert a strong influence on the internal wave climate. During the summers of 2003 and 2004 observational studies were conducted to examine the effects of a western boundary current (the Florida Current), tides, and wind on the mean currents and internal wave field on the outer Southeast Florida shelf. We present evidence that suggests that the Florida Current plays as large a role in the determination of the high frequency internal wave field as tidal forces. These observations and analyses show that it is necessary to include the forcing from the Florida Current meanders and instabilities in order to predict accurately the episodic nature of the internal wave field on the Southeast Florida shelf. Deep ocean and continental shelf processes intersect at the shelf edge and influence the exchange of water masses and their associated characteristics including heat, nutrients, sediment, and larvae across the shelf. Thus, the dynamics of cross-shelf circulation have important consequences for organisms living on the shelf. In the second phase of this work, we investigate physical mechanisms controlling the exchange of water masses during the summer season across the Southeast Florida shelf. A time series of cross-shelf transport from May to August

  7. Controls on reef development and the terrigenous-carbonate interface on a shallow shelf, Nicaragua (Central America)

    Science.gov (United States)

    Roberts, H. H.; Murray, S. P.

    1983-06-01

    Marine geology and physical oceanographic data collected during two field projects (˜4 months) on the Caribbean shelf of Nicaragua indicate a surprising dominance of carbonate deposition and reef growth on a shelf that is receiving an abnormally large volume of terrigenous sediments. High rainfall rates (˜400 500 cm/year), coupled with a warm tropical climate, encourage rapid denudation of the country's central volcanic highland and transport of large volumes of terrigenous sediment and fresh water to the coast. Estimates suggest that three times more fresh water and fifteen times more sediment are introduced per unit length of coastline than on the east coast of the United States. Distribution of the terrigenous facies, development of carbonate sediment suites, and the location and quality of viable reefs are strongly controlled by the dynamic interaction near the coasts of highly turbid fresh to brackish water effluents from thirteen rivers with clear marine waters of the shelf. Oceanic water from the central Caribbean drift current intersects the shelf and moves slowely in a dominant northwest direction toward the Yucatan Channel. A sluggish secondary gyre moves to the south toward Costa Rica. In contrast, the turbid coastal water is deflected to the south in response to density gradients, surface water slopes, and momentum supplied by the steady northeast trade winds. A distinct two-layered flow is commonly present in the sediment-rich coastal boundary zone, which is typically 10 20 km wide. The low-salinity upper layer is frictionally uncoupled from the ambient shelf water and therefore can expand out of the normally coherent coastal boundary zone during periods of abnormal flooding or times when instability is introduced into the northeast trades. Reef distribution, abruptness of the terrigenous-carbonate interface, and general shelf morphology reflect the long-term dynamic structure of the shelf waters. A smooth-bottomed ramp of siliciclastic sands to

  8. Cold shock treatment extends shelf life of naturally ripened or ethylene-ripened avocado fruits.

    Science.gov (United States)

    Chen, Jiao; Liu, Xixia; Li, Fenfang; Li, Yixing; Yuan, Debao

    2017-01-01

    Avocado is an important tropical fruit with high commercial value, but has a relatively short storage life. In this study, the effects of cold shock treatment (CST) on shelf life of naturally ripened and ethylene-ripened avocado fruits were investigated. Fruits were immersed in ice water for 30 min, then subjected to natural or ethylene-induced ripening. Fruit color; firmness; respiration rate; ethylene production; and the activities of polygalacturonase (PG), pectin methylesterase (PME), and endo-β-1,4-glucanase were measured. Immersion in ice water for 30 min effectively delayed ripening-associated processes, including peel discoloration, pulp softening, respiration rate, and ethylene production during shelf life. The delay in fruit softening by CST was associated with decreased PG and endo-β-1,4-glucanase activities, but not PME activity. This method could potentially be a useful postharvest technology to extend shelf life of avocado fruits.

  9. Design concept of Hydro cascade control system

    International Nuclear Information System (INIS)

    Fustik, Vangel; Kiteva, Nevenka

    2006-01-01

    In this paper a design concept of the comple hydro cascade scheme is presented with the design parameters of the main technical features. The cascade control system architecture is designed considering up-to-date communication and information technology. The control algorithm is based on Pond Level Control and Economic Load Allocation concepts.

  10. Centrifugal separator cascade connected in zigzag manner

    International Nuclear Information System (INIS)

    Kai, Tsunetoshi; Inoue, Yoshiya; Oya, Akio; Nagakura, Masaaki.

    1974-01-01

    Object: To effectively accommodate centrifugal separators of the entire cascade within the available space in a plant by freely selecting perpendicular direction of connection of the centrifugal separator. Structure: Centrifugal separators are connected in zigzag fashion by using a single header for each stage so that in a rectangular shape the entire cascade is arranged. (Kamimura, M.)

  11. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  12. Cascading costs: an economic nitrogen cycle.

    Science.gov (United States)

    Moomaw, William R; Birch, Melissa B L

    2005-09-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N(2). We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single ton of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a ton of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that ton would cascade. The analysis reveals that it is most cost effective to remove a ton of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  13. Interaction Between Shelf Layout and Marketing Effectiveness and Its Impact On Optimizing Shelf Arrangements

    NARCIS (Netherlands)

    J.E.M. van Nierop; D. Fok (Dennis); Ph.H.B.F. Franses (Philip Hans)

    2006-01-01

    textabstractAllocating the proper amount of shelf space to stock keeping units [SKUs] is an increasingly relevant and difficult topic for managers. Shelf space is a scarce resource and it has to be distributed across a larger and larger number of items. It is in particular important because the

  14. Interaction Between Shelf Layout and Marketing Effectiveness and Its Impact on Optimizing Shelf Arrangements

    NARCIS (Netherlands)

    van Nierop, Erjen; Fok, Dennis; Franses, Philip Hans

    2008-01-01

    In this paper, we propose and operationalize a new method for optimizing shelf arrangements. We show that there are important dependencies between the layout of the shelf and stock-keeping unit (SKU) sales and marketing effectiveness. The importance of these dependencies is further shown by the

  15. Cascade Error Projection: An Efficient Hardware Learning Algorithm

    Science.gov (United States)

    Duong, T. A.

    1995-01-01

    A new learning algorithm termed cascade error projection (CEP) is presented. CEP is an adaption of a constructive architecture from cascade correlation and the dynamical stepsize of A/D conversion from the cascade back propagation algorithm.

  16. Frozen waterfall (or ice cascade) growth and decay: a thermodynamic approach

    Science.gov (United States)

    Gauthier, Francis; Montagnat, Maurine; Weiss, Jérôme; Allard, Michel; Hétu, Bernard

    2013-04-01

    The ice volume evolution of an ice cascade was studied using a thermodynamic model. The model was developed from meteorological data collected in the vicinity of the waterfall and validated from ice volume measurements estimated from terrestrial LiDAR images. The ice cascade forms over a 45 m high rockwall located in northern Gaspésie, Québec, Canada. Two stages of formation were identified. During the first stage, the growth is mainly controlled by air convection around the flowing and freefalling water. The ice cascade growth rate increases with the decreasing air temperature below 0°C and when the water flow reaches its lowest level. During the second stage, the ice cascade covers the entire rockwall surface, water flow is isolated from the outside environment and ice volume increases asymptotically. Heat is evacuated from the water flow through the ice cover by conduction. The growth is mainly controlled by the radiation energy balance but more specifically by the longwave radiation emitted at the ice surface during the night. In spring, melting of the ice cascade is clearly dependant on the sensible heat carried by the increasing water flow and the diffuse solar radiation received at the ice surface during the day.

  17. Oceanic hydraulic structures for developing a shelf. Issledovaniye morskikh gidrotekhnicheskikh sooruzheniy dlya osvoyenia sel'fa

    Energy Technology Data Exchange (ETDEWEB)

    Simakov, G.B.

    1980-01-01

    The anthology is devoted to practical problems of oceanic hydraulic engineering which arise during design and construction of specialized oceanic hydraulic structures to be erected and used in the shelf zones of seas and oceans. Most of the articles deal with studying the external effect of rough waters, impacts from ships and ice floes on floating and stationary hydraulic structures for developing a shelf. A great deal of attention is also given to the hydrodynamic and anchoring of floating hydraulic structures. The information reflects the current status of the problems of designing and building production facilities for developing a continental shelf.

  18. Displacement cascades in diatomic materials

    International Nuclear Information System (INIS)

    Parkin, D.M.; Coulter, C.A.

    1981-01-01

    A new function, the specified-projectile displacement function p/sub ijk/ (E), is introduced to describe displacement cascades in polyatomic materials. This function describes the specific collision events that produce displacements and hence adds new information not previously available. Calculations of p/sub ijk/ (E) for MgO, Al 2 O 3 and TaO are presented and discussed. Results show that the parameters that have the largest effect on displacement collision events are the PKA energy and the mass ratio of the atom types in the material. It is further shown that the microscopic nature of the displacement events changes over the entire recoil energy range relevant to fusion neutron spectra and that these changes are different in materials whose mass ratio is near one than in those where it is far from one

  19. The Geant4 Bertini Cascade

    Energy Technology Data Exchange (ETDEWEB)

    Wright, D.H.; Kelsey, M.H.

    2015-12-21

    One of the medium energy hadron–nucleus interaction models in the GEANT4 simulation toolkit is based partly on the Bertini intranuclear cascade model. Since its initial appearance in the toolkit, this model has been largely re-written in order to extend its physics capabilities and to reduce its memory footprint. Physics improvements include extensions in applicable energy range and incident particle types, and improved hadron–nucleon cross-sections and angular distributions. Interfaces have also been developed which allow the model to be coupled with other GEANT4 models at lower and higher energies. The inevitable speed reductions due to enhanced physics have been mitigated by memory and CPU efficiency improvements. Details of these improvements, along with selected comparisons of the model to data, are discussed.

  20. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2014-01-01

    attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption......In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  1. Shelf Life Prediction for Canned Gudeg using Accelerated Shelf Life Testing (ASLT) Based on Arrhenius Method

    Science.gov (United States)

    Nurhayati, R.; Rahayu NH, E.; Susanto, A.; Khasanah, Y.

    2017-04-01

    Gudeg is traditional food from Yogyakarta. It is consist of jackfruit, chicken, egg and coconut milk. Gudeg generally have a short shelf life. Canning or commercial sterilization is one way to extend the shelf life of gudeg. This aims of this research is to predict the shelf life of Andrawinaloka canned gudeg with Accelerated Shelf Life Test methods, Arrhenius model. Canned gudeg stored at three different temperature, there are 37, 50 and 60°C for two months. Measuring the number of Thio Barbituric Acid (TBA), as a critical aspect, were tested every 7 days. Arrhenius model approach is done with the equation order 0 and order 1. The analysis showed that the equation of order 0 can be used as an approach to estimating the shelf life of canned gudeg. The storage of Andrawinaloka canned gudeg at 30°C is predicted untill 21 months and 24 months for 25°C.

  2. Experimental study of flow through compressor Cascade

    Directory of Open Access Journals (Sweden)

    Satyam Panchal

    2017-09-01

    Full Text Available The objective of this research work is to study the behaviour of flow at the inlet, within the blade passage and at the exit of a compressor cascade. For this purpose, a cascade with six numbers of aerofoil blades was designed and constructed. The cascade was fitted on the cascade test tunnel. Out of six blades two were instrumented for measuring the pressure distribution on the pressure and suction surface. The blades had a parabolic camber line, with a maximum camber position at 40% of the chord from the leading edge of the blade. The profile of the blade was C4, height of the blade was 160 mm, chord length was 80 mm, camber angle was 45° and stagger angle was 30°. Similarly, the length of the cascade was 300 mm, span was 160 mm, pitch was 60 mm, the actual chord of the cascade was 80 mm, the axial chord of the cascade was 70 mm, the stagger angle of the cascade was 30° and the pitch-chord ratio was 0.75. The data was taken and analyzed at −500% of the axial chord before the cascade, −25% of the axial chord before the leading edge, 25%, 50%, 75% and 150% of the axial chord from the leading edge of the blade. The readings were taken from the cascade wall to the mid span position along the pitch wise direction. The angle of incidence was also changed during the experiment and varied from i=−50°, −30°, −10° to 5°.

  3. [Impacts of hydroelectric cascade exploitation on river ecosystem and landscape: a review].

    Science.gov (United States)

    Yang, Kun; Deng, Xi; Li, Xue-Ling; Wen, Ping

    2011-05-01

    Hydroelectric cascade exploitation, one of the major ways for exploiting water resources and developing hydropower, not only satisfies the needs of various national economic sectors, but also promotes the socio-economic sustainable development of river basin. unavoidable anthropogenic impacts on the entire basin ecosystem. Based on the process of hydroelectric cascade exploitation and the ecological characteristics of river basins, this paper reviewed the major impacts of hydroelectric cascade exploitation on dam-area ecosystems, river reservoirs micro-climate, riparian ecosystems, river aquatic ecosystems, wetlands, and river landscapes. Some prospects for future research were offered, e.g., strengthening the research of chain reactions and cumulative effects of ecological factors affected by hydroelectric cascade exploitation, intensifying the study of positive and negative ecological effects under the dam networks and their joint operations, and improving the research of successional development and stability of basin ecosystems at different temporal and spatial scales.

  4. Hydrography and chlorophyll a in a transect from the coast to the shelf-break in the Argentinian Sea

    Science.gov (United States)

    Carreto, JoséI.; Lutz, Vivian A.; Carignan, Marco O.; Cucchi Colleoni, Angel D.; De Marco, Silvia G.

    1995-03-01

    On the basis of data obtained during eight research cruises from a section of the Buenos Aires province shelf, three systems are characterized: (1) coastal system; (2) subantarctic shelf waters system; and (3) Malvinas system. These domains are frequently separated by two quasipermanent fronts: (1) the coastal front; and (2) the shelf-break front. The patterns of seasonal variation of phytoplankton biomass in these systems are strongly related to changes in vertical stability, that controls the availability of nutrients and light energy. In the coastal system, the mixing produced by winds and tides gives homogenenous waters all year round, having the lowest nitrate concentration and the lowest N:P ratio. The amplitude of the seasonal variation of chlorophyll was relatively small, although the highest concetrations were detected in spring and autumn. The subantarctic shelf waters system is characterized by the typical development and breakdown cycle of the seasonal thermocline. Two well defined chlorophyll a maxima are observed: the main peak during spring and the secondary one during autumn. Geographical differences occur in the timing of the development and breakdown of the thermocline. Another factor of variability is the advection of low salinity waters from the coastal region of the Rio de la Plata during spring. During winter, when nutrient concentration is the highest, an increasing nitrate gradient from the coastal front to the shelf-break region is observed. During summer, surface nitrate concentration is low over the whole continental shelf, and the highest chlorophyll a concentrations are associated with the depth of the pycnocline. However, associated with the surface nitrate maximum, chlorophyll a values higher than 2 mg m -3 are recorded at the shelf-break front. The observed surface maxima are thought to be related to physical processes associated with the slope, where the enhanced mixing results in nutrient renewal and subsequent phytoplankton growth

  5. Risk evaluation for federally listed (roseate tern, piping plover) or candidate (red knot) bird species in offshore waters: A first step for managing the potential impacts of wind facility development on the Atlantic Outer Continental Shelf

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Joanna [Division of Life Sciences, Rutgers University, Piscataway, NJ 08854-8082 (United States); Conserve Wildlife, 516 Farnsworth Avenue, Bordentown, NJ 08505 (United States); Gordon, Caleb; Newman, James; Forcey, Greg [Pandion Systems, Inc. 102 NE 10th Ave, Gainesville, FL 32601 (United States); Lawrence, J. [Conserve Wildlife, 516 Farnsworth Avenue, Bordentown, NJ 08505 (United States); Vlietstra, Lucy [Department of Science, US Coast Guard Academy, 27 Mohegan Drive, New London, CT 06320 (United States)

    2011-01-15

    With a worldwide increase in attention toward developing a reliance on renewable energy, there is a need to evaluate the effects of these facilities (solar, wind, hydropower) on ecosystems. We conduct a hazard and risk evaluation for three species of birds that are listed, or candidates for listing, as federally threatened or endangered in the US, and that might occur offshore on the Atlantic Outer Continental Shelf (AOCS) where wind power facilities could be developed. Our objectives were to: 1) provide conceptual models for exposure for each species, and 2) examine potential exposure and hazards of roseate tern (Sterna dougallii) and piping plover (Charadrius melodus, both federally endangered in the US) and red knot (Calidris canutus rufa, candidate species) in the AOCS. We used a weight-of-evidence approach to evaluate information from a review of technical literature. We developed conceptual models to examine the relative vulnerability of each species as a function of life stage and cycle (breeding, staging, migratory, wintering). These methods are useful for conducting environmental assessments when empirical data are insufficient for a full risk assessment. We determined that 1) Roseate terns are likely to be exposed to risk during the migratory and breeding season when they occur in the AOCS, as well as while staging. 2) Piping plovers are not likely to be at risk during the breeding season, but may be at risk during spring or fall migrations. Risk to this species is likely to be low from turbines located far from land as this species migrates mainly along the coast. 3) Red knots are potentially exposed to some risk during migration, especially long-distance migrants whose migratory routes take them over the AOCS. More information is required on exact spatio-temporal migration routes, flight altitudes (especially during ascent and descent), and behavioral avoidance of turbines by birds to ascertain their risk. (author)

  6. Genetic algorithm based separation cascade optimization

    International Nuclear Information System (INIS)

    Mahendra, A.K.; Sanyal, A.; Gouthaman, G.; Bera, T.K.

    2008-01-01

    The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

  7. Microbiological quality of soft, semi-hard and hard cheeses during the shelf-life

    Directory of Open Access Journals (Sweden)

    Josip Vrdoljak

    2016-03-01

    Full Text Available Cheeses as ready-to-eat food should be considered as a potential source of foodborne pathogens, primarily Listeria monocytogenes. The aim of present study was to determine the microbiological quality of soft, semi-hard and hard cheeses during the shelf-life, with particular reference to L. monocytogenes. Five types of cheeses were sampled at different timepoints during the cold storage and analyzed for presence of Salmonella and L. monocytogenes, as well as lactic acid bacteria, Escherichia coli, coagulase-positive staphylococci, yeasts, molds, sulfite-reducing clostridia and L. monocytogenes counts. Water activity, pH and NaCl content were monitored in order to evaluate the possibility of L. monocytogenes growth. Challenge test for L. monocytogenes was performed in soft whey cheese, to determine the growth potential of pathogen during the shelf-life of product. All analyzed cheeses were compliant with microbiological criteria during the shelf-life. In soft cheeses, lactic acid bacteria increased in the course of the shelf-life period (1.2-2.6 log increase, while in semi-hard and hard cheeses it decreased (1.6 and 5.2 log decrease, respectively. Soft cheeses support the growth of L. monocytogenes according to determined pH values (5.8-6.5, water activity (0.99-0.94, and NaCl content (0.3-1.2%. Challenge test showed that L. monocytogenes growth potential in selected soft cheese was 0.43 log10 cfu/g during 8 days at 4°C. Water activity in semi-hard and hard cheeses was a limiting factor for Listeria growth during the shelf-life. Soft, semi-hard and hard cheeses were microbiologically stable during their defined shelf-life. Good manufacturing and hygienic practices must be strictly followed in the production of soft cheeses as Listeria-supporting food and be focused on preventing (recontamination.

  8. Physico-chemical shelf-life indicators of meat from broilers given ...

    African Journals Online (AJOL)

    The objective of the study was to determine the effect of using Moringa oleifera leaf meal (MOLM) as an additive on physico-chemical shelf life indicators of meat from broilers. A total of 432 1-day-old chicks were randomly allocated to four treatments (TRT's). Water and feed was provided ad libitum. The feeding phases were ...

  9. Zooplankton from the shelf watrs off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Peter, G.

    Zooplankton in the shelf waters of India from Dabhol to Tuticorin was studied during the 17th cruise of R.V. Gaveshani in March 1977. Biomass values were relatively high in the central zone between Mangalore and Alleppey. In the region between...

  10. Holocene submarine terraces on the western continental shelf of India; implications for sea-level changes

    Digital Repository Service at National Institute of Oceanography (India)

    Wagle, B.G.; Vora, K.H.; Karisiddaiah, S.M.; Veerayya, M.; Almeida, F.

    and the shelf break, being more common between 11~' and 20~'N. The terraces are prominent between water depths of 50 and 115 m and occur at six distinct levels: (1) 55-60 m, (2) 65-70 m, (3) 75-80 m, (4) 85-90 m, (5) 95-100 m and (6) 110-115 m...

  11. Seasonal and interannual cross-shelf transport over the Texas and Louisiana continental shelf

    Science.gov (United States)

    Thyng, Kristen M.; Hetland, Robert D.

    2018-05-01

    Numerical drifters are tracked in a hydrodynamic simulation of circulation over the Texas-Louisiana shelf to analyze patterns in cross-shelf transport of materials. While the important forcing mechanisms in the region (wind, river, and deep eddies) and associated flow patterns are known, the resultant material transport is less well understood. The primary metric used in the calculations is the percent of drifters released within a region that cross the 100 m isobath. Results of the analysis indicate that, averaged over the eleven years of the simulation, there are two regions on the shelf - over the Texas shelf during winter, and over the Louisiana shelf in summer - with increased seasonal probability for offshore transport. Among the two other distinct regions, the big bend region in Texas has increased probability for onshore transport, and the Mississippi Delta region has an increase in offshore transport, for both seasons. Some of these regions of offshore transport have marked interannual variability. This interannual variability is correlated to interannual changes in forcing conditions. Winter transport off of the Texas shelf is correlated with winter mean wind direction, with more northerly winds enhancing offshore transport; summer transport off the Louisiana shelf is correlated with Mississippi River discharge.

  12. 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.

  13. SOFT COMPUTING SINGLE HIDDEN LAYER MODELS FOR SHELF LIFE PREDICTION OF BURFI

    Directory of Open Access Journals (Sweden)

    Sumit Goyal

    2012-05-01

    Full Text Available Burfi is an extremely popular sweetmeat, which is prepared by desiccating the standardized water buffalo milk. Soft computing feedforward single layer models were developed for predicting the shelf life of burfi stored at 30g.C. The data of the product relating to moisture, titratable acidity, free fatty acids, tyrosine, and peroxide value were used as input variables, and the overall acceptability score as output variable. The results showed excellent agreement between the experimental and the predicted data, suggesting that the developed soft computing model can alternatively be used for predicting the shelf life of burfi.

  14. Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment

    Directory of Open Access Journals (Sweden)

    V. Brüchert

    2018-01-01

    Full Text Available The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organic-carbon-rich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O2 microelectrode profiling; intact sediment core incubations; 35S-sulfate tracer experiments; pore-water dissolved inorganic carbon (DIC; δ13CDIC; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84 % of the depth-integrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC ∕ NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual end-member calculations, the terrestrial organic carbon contribution varied between 32 and 36 %, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope end-member apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr−1 is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3

  15. Aspects of the QCD cascade

    International Nuclear Information System (INIS)

    Olsson, Magnus.

    1993-02-01

    A model is proposed for the production of transverse jets from diffractively excited protons. We propose that transverse jets can be obtained from gluonic bremsstrahlung in a way similar to the emission in DIS. Qualitative agreement is obtained between the model and the uncorrected data published by the UA8 collaboration. Perturbative QCD in the MLLA approximation is applied to multiple jet production in e + e - -annihilation. We propose modified evolution equations for deriving the jet cross sections, defined in the 'k t ' or 'Durham' algorithm. The mean number of jets as a function of the jet resolution is studied, and analytical predictions are compared to the results of MC simulations. We also study a set of differential-difference equations for multiplicity distributions in e + e - -annihilations, supplemented with appropriate boundary conditions. These equations take into account nonsingular terms in the GLAP splitting functions as well as kinematical constraints related to recoil effects. The presence of retarded terms imply that the cascade develops more slowly and reduces the fluctuations. The solutions agree well with MC simulations and experimental data. (authors)

  16. Water physical and chemical data from current meter and bottle casts from the COLUMBUS ISELIN as part of the Ocean Continental Shelf - Mid Atlantic (OCS - Mid Atlantic) project, 1975-10-27 to 1975-11-06 (NODC Accession 7700454)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water physical and chemical data were collected using current meter and bottle casts from the COLUMBUS ISELIN from October 27, 1975 to November 6, 1975. Data were...

  17. Water physical and chemical data from current meter and bottle casts from the GILLISS as part of the Ocean Continental Shelf - Mid Atlantic (OCS - Mid Atlantic) project, 1976-02-04 to 1976-09-14 (NODC Accession 7700477)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water physical and chemical data were collected using current meter and bottle casts from the GILLISS and other platforms from February 4, 1976 to September 14,...

  18. Bottom-mounted water level recorder data in the Gulf of Alaska as part of the Inner Shelf Transport and Recycling (ISHTAR) project from 05 July 1985 to 09 October 1988 (NODC Accession 0000349)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Depth, pressure, and water temperature data were collected at fixed platforms in the Gulf of Alaska from July 5, 1985 to October 9, 1988. These data were submitted...

  19. Summer Drivers of Atmospheric Variability Affecting Ice Shelf Thinning in the Amundsen Sea Embayment, West Antarctica

    Science.gov (United States)

    Deb, Pranab; Orr, Andrew; Bromwich, David H.; Nicolas, Julien P.; Turner, John; Hosking, J. Scott

    2018-05-01

    Satellite data and a 35-year hindcast of the Amundsen Sea Embayment summer climate using the Weather Research and Forecasting model are used to understand how regional and large-scale atmospheric variability affects thinning of ice shelves in this sector of West Antarctica by melting from above and below (linked to intrusions of warm water caused by anomalous westerlies over the continental shelf edge). El Niño episodes are associated with an increase in surface melt but do not have a statistically significant impact on westerly winds over the continental shelf edge. The location of the Amundsen Sea Low and the polarity of the Southern Annular Mode (SAM) have negligible impact on surface melting, although a positive SAM and eastward shift of the Amundsen Sea Low cause anomalous westerlies over the continental shelf edge. The projected future increase in El Niño episodes and positive SAM could therefore increase the risk of disintegration of West Antarctic ice shelves.

  20. Modelling shelf-ocean exchange and its biogeochemical consequences in coastal upwelling systems

    DEFF Research Database (Denmark)

    Muchamad, Al Azhar

    margin bathymetry, and 3) what processes determine the observed variability of total organic carbon (TOC) content in shelf sediments underlying the upwelling system, with implications for the formation of petroleum source rocks. Here, a numerical ocean modeling approach is used in this thesis to explore...... processes and the development of anoxia/euxinia under the present day or past geological conditions. Thirdly and last, processes controlling distribution of total organic carbon (TOC) content in sediments across the continental margin is evaluated by application of the model to the Benguela upwelling system....... In the model, biological primary production and shelf bottom-water anoxia result in enhanced sedimentary TOC concentrations on the mid shelf and upper slope. The simulated TOCs implicate that bottom lateral transport only has a significant effect on increasing the deposition of the organic carbon on the mid...

  1. Chronicling ice shelf history in the sediments left behind

    Science.gov (United States)

    Rosenheim, B. E.; Subt, C.; Shevenell, A.; Guitard, M.; Vadman, K. J.; DeCesare, M.; Wellner, J. S.; Bart, P. J.; Lee, J. I.; Domack, E. W.; Yoo, K. C.; Hayes, J. M.

    2017-12-01

    Collapsing and retreating ice shelves leave unmistakable sediment sequences on the Antarctic margin. These sequences tell unequivocal stories of collapse or retreat through a typical progression of sub-ice shelf diamicton (marking the past positions of grounding lines), sequentially overlain by a granulated facies from beneath the ice shelf, ice rafted debris from the calving line, and finally open marine sediment. The timelines to these stories, however, are troublesome. Difficulties in chronicling these stories recorded in sediment have betrayed their importance to our understanding of a warming world in many cases. The difficulties involve the concerted lack of preservation/production of calcium carbonate tests from the water column above and admixture of relict organic material from older sources of carbon. Here, we summarize our advances in the last decade of overcoming difficulties associated with the paucity of carbonate and creating chronologies of ice shelf retreat into the deglacial history of Antarctica by exploiting the range of thermochemical stability in organic matter (Ramped PyrOx) from these sediment sequences. We describe our success in comparing Ramped PyrOx 14C dates with foraminiferal dates, the relationship between sediment facies and radiocarbon age spectrum, and our ability to push limits of dating sediments deposited underneath ice shelves. With attention to the caveats of recent dating developments, we summarize expectations that geologist should have when coring the Antarctic margins to discern deglacial history. Perhaps most important among these expectations is the ability to design coring expeditions without regard to our ability to date calcium carbonate microfossils within the cores, in essence removing suspense of knowing whether cores taken from crucial paleo ice channels and other bathymetric features will ultimately yield a robust chronology for its sedimentary sequence.

  2. Holocene sea levels of Visakhapatnam shelf, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.M.; Rao, T.C.S.

    The Holocene sea level changes in the shelf areas off Visakhapatnam was studied from sediment distribution pattern and shallow seismic profiling. Morphological features on the shelf indicate a Late Pleistocene regression down to about -130 m below...

  3. Food packaging and shelf life: a practical guide

    National Research Council Canada - National Science Library

    Robertson, Gordon L

    2010-01-01

    .... Food Packaging and Shelf Life: A Practical Guide provides package developers with the information they need to specify just the right amount of protective packaging to maintain food quality and maximize shelf life...

  4. Seabottom backscatter studies in the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Pathak, D.

    The study is initiated to observe the interaction effects of the sound signal with three different sediment bottoms in the shelf area between Cochin and Mangalore in the western continental shelf of India. An echo signal acquisition system has been...

  5. 75 FR 1076 - Outer Continental Shelf Civil Penalties

    Science.gov (United States)

    2010-01-08

    ... initiate civil penalty proceedings; however, violations that cause injury, death, or environmental damage... DEPARTMENT OF THE INTERIOR Minerals Management Service Outer Continental Shelf Civil Penalties... daily civil penalty assessment. SUMMARY: The Outer Continental Shelf Lands Act requires the MMS to...

  6. Magnetic surveys of the continental shelf off Visakhapatnam

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, T.C.S.; Murthy, K.S.R.

    shelf. Quantitative estimates made for the anomalies over the inner shelf using the graphical method and by computing the analytical signal suggest the existence of a fault in the nearshore region and a possible zone of heavy mineral concentration off...

  7. Bursting behaviours in cascaded stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov—Maxwell system. A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma. It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light, as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction. The bursting time in the reflectivity is found to be less than half the ion acoustic period. The ion temperature can affect the stimulated Brillouin scattering cascade, which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures. For stimulated Brillouin scattering saturation, higher-harmonic generation and wave—wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter. In addition, stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light. (physics of gases, plasmas, and electric discharges)

  8. Defect accumulation under cascade damage conditions

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, B.N.; Woo, C.H.

    1994-01-01

    in terms of this reaction kinetics taking into account cluster production, dissociation, migration and annihilation at extended sinks. Microstructural features which are characteristic of cascade damage and cannot be explained in terms of the conventional single defect reaction kinetics are emphasized......There is now ample evidence from both experimental and computer simulation studies that in displacement cascades not only intense recombination takes place but also efficient clustering of both self-interstitial atoms (SIAs) and vacancies. The size distributions of the two types of defects produced...... reactions kinetics associated with the specific features of cascade damage is described, with emphasis on asymmetries between SIA and vacancy type defects concerning their production, stability, mobility and interactions with other defects. Defect accumulation under cascade damage conditions is discussed...

  9. Cascade theory in isotopic separation processes

    International Nuclear Information System (INIS)

    Agostini, J.P.

    1994-06-01

    Three main areas are developed within the scope of this work: - the first one is devoted to fundamentals: separative power, value function, ideal cascade and square cascade. Applications to two main cases are carried out, namely: Study of binary isotopic mix, Study of processes with a small enrichment coefficient. - The second one is devoted to cascade coupling -high-flux coupling (more widely used and better known) as well as low-flux coupling are presented and compared to one another. - The third one is an outlook on problems linked to cascade transients. Those problem are somewhat intricate and their interest lies mainly into two areas: economics where the start-up time may have a large influence on the interests paid during the construction and start-up period, military productions where the start-up time has a direct bearing on the production schedule. (author). 50 figs. 3 annexes. 12 refs. 6 tabs

  10. τ polarization in SUSY cascade decays

    International Nuclear Information System (INIS)

    Choi, S.Y.; Hagiwara, K.; Kim, Y.G.

    2006-12-01

    τ leptons emitted in cascade decays of supersymmetric particles are polarized. The polarization may be exploited to determine spin and mixing properties of the neutralinos and stau particles involved. (orig.)

  11. MAP kinase cascades in Arabidopsis innate immunity

    DEFF Research Database (Denmark)

    Rasmussen, Magnus Wohlfahrt; Roux, Milena Edna; Petersen, Morten

    2012-01-01

    Plant mitogen-activated protein kinase (MAPK) cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs) by host transmembrane pattern recognition receptors which trigger MAPK-dependent innate ...

  12. Cascade processes in kaonic and muonic atoms

    International Nuclear Information System (INIS)

    Faifman, M.P.; Men'shikov, L.I.

    2003-01-01

    Cascade processes in exotic (kaonic and muonic) hydrogen/deuterium have been studied with the quantum-classical Monte Carlo code (QCMC) developed for 'ab initio' - calculations. It has been shown that the majority of kaonic hydrogen atoms during cascade are accelerated to high energies E ∼ 100 eV, which leads to a much lower value for the calculated yields Y of x-rays than predicted by the 'standard cascade model'. The modified QCMC scheme has been applied to the study of the cascade in μp and μd muonic atoms. A comparison of the calculated yields for K-series x-rays with experimental data directly indicates that the molecular structure of the hydrogen target and new types of non-radiative transitions are essential for the light muonic atoms, while they are negligible for heavy (kaonic) atoms. These processes have been considered and estimates of their probabilities are presented. (author)

  13. Cascade Error Projection: A New Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.; Thakoor, A. P.

    1995-01-01

    A new neural network architecture and a hardware implementable learning algorithm is proposed. The algorithm, called cascade error projection (CEP), handles lack of precision and circuit noise better than existing algorithms.

  14. Plankton community respiration, net ecosystem metabolism, and oxygen dynamics on the Louisiana continental shelf: Implications for hypoxia

    Science.gov (United States)

    Murrell, Michael C.; Stanley, Roman S.; Lehrter, John C.; Hagy, James D.

    2013-01-01

    We conducted a multi-year study of the Louisiana continental shelf (LCS) to better understand the linkages between water column metabolism and the formation of hypoxia (dissolved oxygen Continental Shelf Research, 29: 1861-1872) to estimate net water column metabolism. There was consistent evidence of net heterotrophy, particularly in western transects, and in deeper waters (>40 m depth), indicating a net organic carbon deficit on the LCS. We offer a simple scale argument to suggest that riverine and inshore coastal waters may be significant sources of organic carbon to account for this deficit. This study provided unprecedented, continental shelf scale coverage of heterotrophic metabolism, which is useful for constraining models of oxygen, carbon, and nutrient dynamics along the LCS.

  15. Influence of estuaries on shelf sediment texture

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, R.R.; Hashimi, N.H.

    on the coast. Offshore from regions where there are a large number of estuaries, the inner shelf sediments are fine grained (average mean size 5.02 phi, 0.03 mm), rich in organic matter ( 2%) and low in calcium carbonate ( 25%). In contrast, in regions...

  16. Cosmetics Safety Q&A: Shelf Life

    Science.gov (United States)

    ... of cosmetics? The shelf life for eye-area cosmetics is more limited than for other products. Because of repeated microbial exposure during use by the consumer and the risk of eye infections, some industry experts recommend replacing mascara 3 months after purchase. ...

  17. Coordination: Southeast Continental Shelf studies. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, D.W.

    1981-02-01

    An overview of the Oceanograhic Program of Skidaway Institute of Oceanograhy is presented. Included are the current five year plan for studies of the Southeast Continental Shelf, a summary of research accomplishments, proposed research for 1981-1982, current status of the Savannah Navigational Light Tower, and a list of publications. (ACR)

  18. Inter-annual variability of exchange processes at the outer Black Sea shelf

    Science.gov (United States)

    Shapiro, Georgy; Wobus, Fred; Yuan, Dongliang; Wang, Zheng

    2014-05-01

    The advection of cold water below the surface mixed layer has a significant role in shaping the properties of the Cold Intermediate Layer (CIL) in the Black Sea, and thus the horizontal redistribution of nutrients. The minimal temperature of the CIL in the southwest deep region of the sea in summer was shown to be lower than the winter surface temperature at the same location, indicating the horizontal advective nature of CIL formation in the area (Kolesnikov, 1953). In addition to advection in the deep area of the sea, the transport of cold waters from the northwest Black Sea shelf across the shelf break in winter was shown to contribute to the formation of the CIL (Filippov, 1968; Staneva and Stanev, 1997). However less is known of the exchanges between the CIL waters and the outer shelf areas in summer, when a surface mixed layer and the underlying seasonal thermocline are formed. Ivanov et al. (1997) suggested that the cross frontal exchange within the CIL is strongly inhibited, so that CIL waters formed in the deep sea (i.e. offshore of the Rim Current) do not replenish the CIL waters onshore of the Rim Current (also known as near-bottom shelf waters, or BSW), due to strong cross frontal gradients in potential vorticity (PV). To the contrary, Shapiro et al. (2011) analysed in-situ observations over the period of 1950-2001 and showed a high correlation between the CIL temperatures in the open sea and outer shelf. However, the statistical methods alone were not able to clearly establish the relation between the cause and the consequences. In this study we use a 3D numerical model of the Black Sea (NEMO-SHELF-BLS) to quantify the exchange of CIL waters between the open sea and the outer northwest Black Sea shelf and to assess its significance for the replenishment of BSW on the outer shelf. The model has a resolution of 1/16º latitude × 1/12º longitude and 33 levels in the vertical. In order to represent near-bottom processes better, the model uses a hybrid

  19. Simulation of concentration spikes in cascades

    International Nuclear Information System (INIS)

    Wood, H.G.

    2006-01-01

    Research has been conducted to investigate the maximum possible enrichment that might be temporarily achieved in a facility that is producing enriched uranium for fuel for nuclear power reactors. The purpose is to provide information to evaluate if uranium enrichment facilities are producing 235 U enriched within declared limits appropriate for power reactors or if the facilities are actually producing more highly enriched uranium. The correlation between feed rate and separation factor in a gas centrifuge cascade shows that as flow decreases, the separation factor increases, thereby, creating small amounts of higher enriched uranium than would be found under optimum design operating conditions. The research uses a number of cascade enrichment programs to model the phenomenon and determine the maximum enrichment possible during the time transient of a gas centrifuge cascade. During cascade start-up, the flow through the centrifuges begins at lower than centrifuge design stage flow rates. Steady-state cascade models have been used to study the maximum 235 U concentrations that would be predicted in the cascade. These calculations should produce an upper bound of product concentrations expected during the transient phase of start-up. Due to the fact that there are different ways in which to start a cascade, several methods are used to determine the maximum enrichment during the time transient. Model cascades were created for gas centrifuges with several product to .feed assay separation factors. With this information, the models were defined and the equilibrium programs were used to determine the maximum enrichment level during the time transient. The calculations predict in a cascade with separation factor 1.254 designed to produce enriched uranium for the purpose of supplying reactor fuel, it would not be unreasonable to see some 235 U in the range of 12-15%. Higher assays produced during the start-up period might lead inspectors to believe the cascade is being

  20. Designing the Cascade inertial confinement fusion reactor

    International Nuclear Information System (INIS)

    Pitts, J.H.

    1987-01-01

    The primary goal in designing inertial confinement fusion (ICF) reactors is to produce electrical power as inexpensively as possible, with minimum activation and without compromising safety. This paper discusses a method for designing the Cascade rotating ceramic-granule-blanket reactor (Pitts, 1985) and its associated power plant (Pitts and Maya, 1985). Although focus is on the cascade reactor, the design method and issues presented are applicable to most other ICF reactors

  1. High energy evolution of soft gluon cascades

    International Nuclear Information System (INIS)

    Shuvaev, A.; Wallon, S.

    2006-01-01

    In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)

  2. High energy evolution of soft gluon cascades

    Energy Technology Data Exchange (ETDEWEB)

    Shuvaev, A. [St. Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg district (Russian Federation); Wallon, S. [Universite Paris XI, Laboratoire de Physique Theorique, Orsay Cedex (France)

    2006-04-15

    In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)

  3. Cascade of links in complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yeqian; Sun, Bihui [Department of Management Science, School of Government, Beijing Normal University, 100875 Beijing (China); Zeng, An, E-mail: anzeng@bnu.edu.cn [School of Systems Science, Beijing Normal University, 100875 Beijing (China)

    2017-01-30

    Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

  4. Cascade of links in complex networks

    International Nuclear Information System (INIS)

    Feng, Yeqian; Sun, Bihui; Zeng, An

    2017-01-01

    Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

  5. Defect production in simulated cascades: Cascade quenching and short-term annealing

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1983-01-01

    Defect production in displacement cascades in copper has been modeled using the MARLOWE code to generate cascades and the stochastic annealing code ALSOME to simulate cascade quenching and short-term annealing of isolated cascades. Quenching is accomplished by using exaggerated values for defect mobilities and for critical reaction distances in ALSOME for a very short time. The quenched cascades are then short-term annealed with normal parameter values. The quenching parameter values were empirically determined by comparison with results of resistivity measurements. Throughout the collisional, quenching and short-term annealing phases of cascade development, the high energy cascades continue to behave as a collection of independent lower energy lobes. For recoils above about 30 keV the total number of defects and the numbers of free defects scale with the damage energy. As the energy decreases from 30 keV, defect production varies with the changing nature of the cascade configuration, resulting in more defects per unit damage energy. The simulated annealing of a low fluence of interacting cascades revealed an interstitial shielding effect on depleted zones during Stage I recovery. (orig.)

  6. Research on Cascade Reservoirs’ Short-Term Optimal Operation under the Effect of Reverse Regulation

    Directory of Open Access Journals (Sweden)

    Changming Ji

    2018-06-01

    Full Text Available Currently research on joint operation of a large reservoir and its re-regulating reservoir focuses on either water quantity regulation or water head regulation. The accuracy of relevant models is in need of improvement if the influence of factors such as water flow hysteresis and the aftereffect of tail water level variation are taken into consideration. In this paper, given the actual production of Pankou-Xiaoxuan cascade hydropower stations that combines two operation modes (‘electricity to water’ and ‘water to electricity’, a coupling model of their short-term optimal operation is developed, which considers Xiaoxuan reservoir’s regulating effect on Pankou reservoir’s outflow volume and water head. Factors such as water flow hysteresis and the aftereffect of tail water level variation are also considered to enhance the model’s accuracy. The Backward Propagation (BP neural network is employed for precise calculation of the downstream reservoir’s inflow and the upstream reservoir’s tail water level. Besides, we put forth Accompanying Progressive Optimality Algorithm (APOA to solve the coupling model with aftereffect. An example is given to verify the scientificity of the proposed model and the advantages of APOA. Through analysis of the model calculation results, the optimal operation rules of the cascade reservoirs are obtained in terms of water quantity regulation and water head regulation, which can provide scientific reference for cascade reservoirs’ optimal operation.

  7. Cascade system using both trough system and dish system for power generation

    International Nuclear Information System (INIS)

    Zhang, Cheng; Zhang, Yanping; Arauzo, Inmaculada; Gao, Wei; Zou, Chongzhe

    2017-01-01

    Highlights: • A novel solar cascade system using both trough and dish collectors is proposed. • Heat rejected by the Stirling engines is collected by the condensed water. • The directions to increase the efficiency improvement has been pointed out • Influence of flow type of heating/cooling fluids of Stirling engines is considered. - Abstract: This paper represents a novel solar thermal cascade system using both trough and dish systems for power generation. An effective structure using the condensed fluid of Rankine cycle to cool the Stirling engines to use the heat released by Stirling engines was proposed. The cascade system model with different fluid circuits was developed. The models of some important components of the system, such as dish collector, trough collector and Stirling engine array, are presented with detail explanation in this paper. Corresponding stand-alone systems were also developed for comparison. Simulations were conducted with the models to find out efficiency difference between cascade system and corresponding stand-alone systems. The directions to increase the efficiency difference were also considered. Results show that the cascade system can achieve a higher efficiency with a high solar irradiance (>550 W/m"2). The flow type of fluids between heating and cooling Stirling engine array is also required to concern on designing a cascade system with Stirling engine array.

  8. Formalism of continual integrals for cascade processes with particle fusion

    International Nuclear Information System (INIS)

    Gedalin, Eh.V.

    1987-01-01

    Formalism of continuous integrals for description of cascade processes, in which besides cascade particle reproduction, their synthesis and coalescence take place, is used. Account of cascade particle coalescence leads to the fact that the development of some cascade branches cannot be independent and main equations of the cascade process become functional instead of integral. The method of continuous intagrals permits to construct in the closed form producing functionals for the cascade process and to obtain the rules of their calculation using diagrams. Analytical expressions in the form of continuous integrals for producing functionals describing cascade development are obtained

  9. Experimental and theoretical study of cascade solar stills in Iran

    International Nuclear Information System (INIS)

    Tabrizi, F.F.; Sharak, A.Z.

    2009-01-01

    Due to low annual rainfall, most of Iran is dominated by arid and semi-arid areas. The solar radiation intensity is extremely high in most of the country. The need to produce fresh water from brackish water is considerably high, especially in dry regions. Desalination of brackish water may become a competitive potential water resource to meet potable water demand, and as the price of oil goes higher, using solar energy for water desalinisation becomes more economical. This paper presented a study that involved mathematical modeling of the first solar still in Iran. The cumulative fresh water production and water temperature were calculated as a function of time. The obtained results were verified by one month daily-based experimental data. The paper also provided background information on the Koshk village, situated in the south part of Iran near Badar Abbas city. Various investigations regarding meteorological conditions, economical considerations, and technical and operational appropriateness demonstrated that the cascade solar still is suitable for desalination of brackish water. 100 solar stills were installed at the site to provide potable water for a nearby village. It was concluded that the model could be used to simulate and optimize the effective design parameters in future studies. 6 refs., 7 figs

  10. Shelf life prediction of canned fried-rice using accelerated shelf life testing (ASLT) arrhenius method

    Science.gov (United States)

    Kurniadi, M.; Bintang, R.; Kusumaningrum, A.; Nursiwi, A.; Nurhikmat, A.; Susanto, A.; Angwar, M.; Triwiyono; Frediansyah, A.

    2017-12-01

    Research on shelf-life prediction of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius model has been conducted. The aim of this research to predict shelf life of canned-fried rice products. Lethality value of 121°C for 15 and 20 minutes and Total Plate count methods are used to determine time and temperatures of sterilization process.Various storage temperatures of ASLT Arrhenius method were 35, 45 and 55°C during 35days. Rancidity is one of the derivation quality of canned fried rice. In this research, sample of canned fried rice is tested using rancidity value (TBA). TBA value was used as parameter which be measured once a week periodically. The use of can for fried rice without any chemical preservative is one of the advantage of the product, additionaly the use of physicalproperties such as temperature and pressure during its process can extend the shelf life and reduce the microbial contamination. The same research has never done before for fried rice as ready to eat meal. The result showed that the optimum conditions of sterilization process were 121°C,15 minutes with total plate count number of 9,3 × 101 CFU/ml. Lethality value of canned fried rice at 121°C,15 minutes was 3.63 minutes. The calculated Shelf-life of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius method was 10.3 months.

  11. Geologic Map of the Cascade Head Area, Northwestern Oregon Coast Range (Neskiwin, Nestucca Bay, Hebo, and Dolph 7.5 minute Quadrangles)

    Science.gov (United States)

    Snavely, Parke D.; Niem, Alan; Wong, Florence L.; MacLeod, Norman S.; Calhoun, Tracy K.; Minasian, Diane L.; Niem, Wendy

    1996-01-01

    The geology of the Cascade Head area bridges the geology in the Tillamook Highlands to the north (Wells and others, 1994; 1995) with that of the Newport Embayment on the south (Snavely and others, 1976 a,b,c). The four 7.5-minute quadrangles (Neskowin, Nestucca Bay, Hebo, and Dolph) which comprise the Cascade Head area include significant stratigraphic, structural, and igneous data that are essential in unraveling the geology of the northern and central part of the Oregon Coast Range and of the adjacent continental shelfEarlier studies (Snavely and Vokes, 1949) were of a broad reconnaissance nature because of limited access in this rugged, densely forested part of the Siuslaw National Forest. Also, numerous thick sills of late middle Eocene diabase and middle Miocene basalt mask the Eocene stratigraphic relationships. Previous mapping was hampered by a lack of precise biostratigraphic data. However, recent advances in biostratigraphy and radiometric age dating and geochemistry have provided the necessary tools to decipher stratigraphic and structural relationships in the Eocene sedimentary and volcanic rock sequences (W.W. Rau, personal communication, 1978 to 1988; Bukry and Snavely, 1988). Many important stratigraphic and igneous relationships are displayed within the Casacde Head area: (1) turbidite sandstone of the middle Eocene Tyee Formation, which is widespread in the central and southern part of the Oregon Coast Range (Snavely and others, 1964), was not deposited in the western part of the Cascade Head, and is of limited extent north of the map area (Wells and others, 1994); (2) the late middle Eocene Yamhill Formation, which crops out along the west and east flank of the Oregon Coast Range, overlaps older strata and overlies an erosional unconformity on the lower Eocene Siletz River Volcanics (Snavely and others, 1990; 1991); (3) thick sills of late middle Eocene diabase (43 Ma) are widespread in the Cascade Head area and also form much of the eastern

  12. Sediment transport on the Palos Verdes shelf, California

    Science.gov (United States)

    Ferre, B.; Sherwood, C.R.; Wiberg, P.L.

    2010-01-01

    rates (???5 mm yr-1), but do not preclude higher localized rates near abrupt transitions in sediment characteristics. However, low particle settling velocities and strong currents result in transport length-scales that are long relative to the narrow width of the PV shelf, which combined with the significant offshore component in transport, means that transport of resuspended sediment towards deep water is as likely as transport along the axis of the effluent-affected deposit.

  13. Signatures of Late Quaternary sea-level changes and Neo-tectonic activity over Visakhapatnam - Gopalpur shelf, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.M.; Reddy, N.P.C; PremKumar, M.K.; Raju, Y.S.N.; Venkateswarlu, K.; Murthy, K.S.R.

    High-resolution shallow seismic and echo sounding profiles of the continental shelf between Visakhapatnam and Gopalpur reveal prominent morphological features like terraces, reefs and pinnacles at different water depths of 80-100 m, 50-30 m...

  14. Uranium geochemistry on the Amazon shelf: Chemical phase partitioning and cycling across a salinity gradient

    International Nuclear Information System (INIS)

    Swarzenski, P.W.; McKee, B.A.; Booth, J.G.

    1995-01-01

    The size distribution of U was examined in surface waters of the Amazon shelf. Water samples were collected during a low discharge river stage across a broad salinity gradient (0.3-35.4%) and fractionated by planar filtration and tangential-flow ultrafiltration into (1) solution (U s , c , 10,000 MW-0.4 μm), (3) dissolved (U d p >0.4 μm) phases. Concentrations of colloidal U comprise up to 92% of the dissolved U fraction at the river mouth and attain highest values (∼0.45 μg/L) in the productive, biogenic region of the Amazon shelf (salinities above ∼20%). U d and U c distributions are highly nonconservative relative to ideal dilution of river water and seawater, indicating extensive removal at salinities below ∼10%. The distribution of U s also shows some nonconservative behavior, yet removal, if any, is minimal. Saltwater-induced precipitation and aggregation of riverine colloidal material is most likely the dominant mechanism of U removal in the low salinity, terrigenous region of the Amazon shelf. There is evident of a substantial colloidal U input (∼245% of the riverine U c flux) into surface waters above 5%. Such U c enrichment most likely is the result of colloidal U-rich porewater diffusion/advection from the seabed and fluid muds or shelf-wide particle-colloid disaggregation. Removal of solution and dissolved phase U via a colloidal intermediate and U c aggregation in terms of coagulation phase U via a colloidal intermediate and U c aggregation was examined in terms of coagulation theory. The high reactive nature of all U phases on the Amazon shelf suggests that remobilization and fractionation of U may also occur in other river-influenced coastal environments

  15. Fun at Antarctic grounding lines: Ice-shelf channels and sediment transport

    Science.gov (United States)

    Drews, Reinhard; Mayer, Christoph; Eisen, Olaf; Helm, Veit; Ehlers, Todd A.; Pattyn, Frank; Berger, Sophie; Favier, Lionel; Hewitt, Ian H.; Ng, Felix; Fürst, Johannes J.; Gillet-Chaulet, Fabien; Bergeot, Nicolas; Matsuoka, Kenichi

    2017-04-01

    Meltwater beneath the polar ice sheets drains, in part, through subglacial conduits. Landforms created by such drainages are abundant in areas formerly covered by ice sheets during the last glacial maximum. However, observations of subglacial conduit dynamics under a contemporary ice sheet are lacking. We present results from ice-penetrating radar to infer the existence of subglacial conduits upstream of the grounding line of Roi Baudouin Ice Shelf, Antarctica. The conduits are aligned with ice-shelf channels, and underlain by esker ridges formed from sediment deposition due to reduced water outflow speed near the grounding line. In turn, the eskers modify local ice flow to initiate the bottom topography of the ice-shelf channels, and create small surface ridges extending onto the shelf. Relict features on the shelf are interpreted to indicate a history of these interactions and variability of past subglacial drainages. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation, and ice-shelf stability. To investigate the role of sediment transport beneath ice sheets further, we model the sheet-shelf system of the Ekstömisen catchment, Antarctica. A 3D finite element model (Elmer/ICE) is used to solve the transients full Stokes equation for isotropic, isothermal ice with a dynamic grounding line. We initialize the model with surface topography from the TanDEM-X satellites and by inverting simultaneously for ice viscosity and basal drag using present-day surface velocities. Results produce a flow field which is consitent with sattelite and on-site observations. Solving the age-depth relationship allows comparison with radar isochrones from airborne data, and gives information about the atmospheric/dynamic history of this sector. The flow field will eventually be used to identify potential sediment sources and sinks which we compare with more than 400 km of

  16. Mobile Bay river plume mixing in the inner shelf

    Science.gov (United States)

    Parra, S. M.; Book, J. W.; Warner, S. J.; Moum, J.

    2017-12-01

    The microtidal region (0.5 m spring tides) of the inner shelf outside Mobile Bay presented a complex circulation pattern driven by the pulsed river discharge and winds. Currents, salinity, temperature, and turbulence profiles were measured for up to three weeks in April 2016 at six moorings outside Mobile Bay. Currents varied between locations and with depth. During neap and spring tides the currents were reliably >0.4 and 0.5 m/s) and toward deeper waters, concurrent with the strongest stratification. The possible flow drivers considered include tides, winds, inertial oscillations, waves, and stratification. Turbulent kinetic energy production and dissipation were calculated with multiple methods using data from bottom-mounted, upward-looking acoustic Doppler current profilers sampling at 1 Hz, and using data from line-moored chi-pod turbulent temperature microstructure instruments sampling at 100 Hz. This work explores different forcing mechanisms involved in modulating the circulation and turbulence in a multi-layered pulsed-river inner shelf region in the Gulf of Mexico.

  17. Seasonal Dynamics of Dissolved Organic Carbon Under Complex Circulation Schemes on a Large Continental Shelf: The Northern South China Sea

    Science.gov (United States)

    Meng, Feifei; Dai, Minhan; Cao, Zhimian; Wu, Kai; Zhao, Xiaozheng; Li, Xiaolin; Chen, Junhui; Gan, Jianping

    2017-12-01

    We examined the distribution and seasonality of dissolved organic carbon (DOC) based on a large data set collected from the northern South China Sea (NSCS) shelf under complex circulation schemes influenced by river plume, coastal upwelling, and downwelling. The highest surface values of ˜117 μmol L-1 were observed nearshore in summer suggesting high DOC supplies from the river inputs, whereas the lowest surface values of ˜62 μmol L-1 were on the outer shelf in winter due to entrainment of DOC-poor subsurface water under strengthened vertical mixing. While the summer coastal upwelling brought lower DOC from offshore depth to the nearshore surface, the winter coastal downwelling delivered higher surface DOC to the midshelf deep waters from the inner shelf fueled by the China Coastal Current (CCC) transporting relatively high DOC from the East China Sea to the NSCS. The intensified winter downwelling generated a cross-shelf DOC transport of 3.1 × 1012 g C over a large shelf area, which induced a significant depression of the NSCS DOC inventory in winter relative to in autumn. In addition to the variable physical controls, net biological production of DOC was semiquantified in both the river plume (2.8 ± 3.0 μmol L-1) and coastal upwelling (3.1 ± 1.3 μmol L-1) in summer. We demonstrated that the NSCS shelf had various origins of DOC including riverine inputs, inter-shelf transport and in situ production. Via cross-shelf transport, the accumulated DOC would be exported to and stored in the deep ocean, suggesting that continental shelves are a potentially effective carbon sink.

  18. Zooplankton and ichthyoplankton distribution on the southern Brazilian shelf: an overview

    Directory of Open Access Journals (Sweden)

    Rubens M. Lopes

    2006-06-01

    Full Text Available The southern Brazilian coast is the major fishery ground for the Brazilian sardine (Sardinella brasiliensis, a species responsible for up to 40% of marine fish catches in the region. Fish spawning and recruitment are locally influenced by seasonal advection of nutrient-rich waters from both inshore and offshore sources. Plankton communities are otherwise controlled by regenerative processes related to the oligotrophic nature of the Tropical Water from the Brazil Current. As recorded in other continental margins, zooplankton species diversity increases towards outer shelf and open ocean waters. Peaks of zooplankton biomass and ichthyoplankton abundance are frequent on the inner shelf, either at upwelling sites or off large estuarine systems. However, meandering features of the Brazil Current provide an additional mechanism of upward motion of the cold and nutrient-rich South Atlantic Central Water, increasing phyto- and zooplankton biomass and production on mid- and outer shelves. Cold neritic waters originating off Argentina, and subtropical waters from the Subtropical Convergence exert a strong seasonal influence on zooplankton and ichthyoplankton distribution towards more southern areas. This brief review highlights the need for further experimental studies on zooplankton life cycle strategies in order to understand the major processes controlling food web dynamics in this shelf ecosystem.

  19. Habitat specialization in tropical continental shelf demersal fish assemblages.

    Directory of Open Access Journals (Sweden)

    Ben M Fitzpatrick

    Full Text Available The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304 collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1-10 m depth, down the fore reef slope to the reef base (10-30 m depth then across the adjacent continental shelf (30-110 m depth. Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of

  20. Defect production in simulated cascades: cascade quenching and short-term annealing

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1982-01-01

    Defect production in high energy displacement cascades has been modeled using the computer code MARLOWE to generate the cascades and the stochastic computer code ALSOME to simulate the cascade quenching and short-term annealing of isolated cascades. The quenching is accomplished by using ALSOME with exaggerated values for defect mobilities and critical reaction distanes for recombination and clustering, which are in effect until the number of defect pairs is equal to the value determined from resistivity experiments at 4K. Then normal mobilities and reaction distances are used during short-term annealing to a point representative of Stage III recovery. Effects of cascade interactions at low fluences are also being investigated. The quenching parameter values were empirically determined for 30 keV cascades. The results agree well with experimental information throughout the range from 1 keV to 100 keV. Even after quenching and short-term annealing the high energy cascades behave as a collection of lower energy subcascades and lobes. Cascades generated in a crystal having thermal displacements were found to be in better agreement with experiments after quenching and annealing than those generated in a non-thermal crystal

  1. Community cascades in a marine pelagic food web controlled by the non-visual apex predator Mnemiopsis leidyi

    DEFF Research Database (Denmark)

    Tiselius, Peter; Møller, Lene Friis

    2017-01-01

    Trophic cascades are a ubiquitous feature of many terrestrial and fresh-water food webs, but have been difficult to demonstrate in marine systems with multispecies trophic levels. Here we describe significant trophic cascades in an open coastal planktonic ecosystem exposed to an introduced top...... predator. The ctenophore Mnemiopsis leidyi was monitored for an 8-year period concurrent with measures of the food web structure of the plankton and strong trophic cascades were evident. In the 5 years when M. leidyi were found, their target prey (grazing copepods) were reduced 5-fold and the primary...

  2. Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment

    Directory of Open Access Journals (Sweden)

    O. D. Shishkina

    2013-10-01

    Full Text Available An interaction of internal solitary waves with the shelf edge in the time periods related to the presence of a pronounced seasonal pycnocline in the Red Sea and in the Alboran Sea is analysed via satellite photos and SAR images. Laboratory data on transformation of a solitary wave of depression while passing along the transverse bottom step were obtained in a tank with a two-layer stratified fluid. The certain difference between two characteristic types of hydrophysical phenomena was revealed both in the field observations and in experiments. The hydrological conditions for these two processes were named the "deep" and the "shallow" shelf respectively. The first one provides the generation of the secondary periodic short internal waves – "runaway" edge waves – due to change in the polarity of a part of a soliton approaching the shelf normally. Another one causes a periodic shear flow in the upper quasi-homogeneous water layer with the period of incident solitary wave. The strength of the revealed mechanisms depends on the thickness of the water layer between the pycnocline and the shelf bottom as well as on the amplitude of the incident solitary wave.

  3. Mean hydrography on the continental shelf from 26 repeat glider deployments along Southeastern Australia

    Science.gov (United States)

    Schaeffer, Amandine; Roughan, Moninya; Austin, Tim; Everett, Jason D.; Griffin, David; Hollings, Ben; King, Edward; Mantovanelli, Alessandra; Milburn, Stuart; Pasquer, Benedicte; Pattiaratchi, Charitha; Robertson, Robin; Stanley, Dennis; Suthers, Iain; White, Dana

    2016-08-01

    Since 2008, 26 glider missions have been undertaken along the continental shelf of southeastern Australia. Typically these missions have spanned the continental shelf on the inshore edge of the East Australian Current from 29.5-33.5°S. This comprehensive dataset of over 33,600 CTD profiles from the surface to within 10 m of the bottom in water depths ranging 25-200 m provides new and unprecedented high resolution observations of the properties of the continental shelf waters adjacent to a western boundary current, straddling the region where it separates from the coast. The region is both physically and biologically significant, and is also in a hotspot of ocean warming. We present gridded mean fields for temperature, salinity and density, but also dissolved oxygen and chlorophyll-a fluorescence indicative of phytoplankton biomass. This data will be invaluable for understanding shelf stratification, circulation, biophysical and bio-geochemical interactions, as well as for the validation of high-resolution ocean models or serving as teaching material.

  4. Microgreens: Production, shelf life, and bioactive components.

    Science.gov (United States)

    Mir, Shabir Ahmad; Shah, Manzoor Ahmad; Mir, Mohammad Maqbool

    2017-08-13

    Microgreens are emerging specialty food products which are gaining popularity and increased attention nowadays. They are young and tender cotyledonary leafy greens that are found in a pleasing palette of colors, textures, and flavors. Microgreens are a new class of edible vegetables harvested when first leaves have fully expanded and before true leaves have emerged. They are gaining popularity as a new culinary ingredient. They are used to enhance salads or as edible garnishes to embellish a wide variety of other dishes. Common microgreens are grown mainly from mustard, cabbage, radish, buckwheat, lettuce, spinach, etc. The consumption of microgreens has nowadays increased due to higher concentrations of bioactive components such as vitamins, minerals, and antioxidants than mature greens, which are important for human health. However, they typically have a short shelf life due to rapid product deterioration. This review aimed to evaluate the postharvest quality, potential bioactive compounds, and shelf life of microgreens for proper management of this specialty produce.

  5. Links between phytoplankton dynamics and shell growth of Arctica islandica on the Faroe Shelf

    Science.gov (United States)

    Bonitz, Fabian Georg Wulf; Andersson, Carin; Trofimova, Tamara; Hátún, Hjálmar

    2018-03-01

    The phytoplankton dynamics on the Faroe Shelf are strongly connected to higher trophic levels, and their inter-annual variability has great importance for many organisms, including the principal fish stocks. Hence, information on the marked phytoplankton variability is scientifically and economically valuable. We show here that the shell growth variability in Arctica islandica shells has the potential to identify periods of increased and decreased phytoplankton concentrations on the Faroe Shelf and in the wider Faroese region in previous centuries. The growth of A. islandica has often been linked to changes in phytoplankton concentrations, i.e., food availability. By cross-matching life-collected and sub-fossil A. islandica shells from two separate locations on the Faroe Shelf, we have built a master chronology, which reaches back to the 17th century. This master chronology correlates well with a Primary Production index for the Faroe Shelf (r = 0.65; p phytoplankton concentrations over the wider Faroese Channel Region, as represented in the Continuous Plankton Recorder surveys, especially for the months June-September (r = 0.39; p < 0.01). In addition, an inverse relationship is observed between the master chronology and on-shelf water temperatures from June-September (r = - 0.29; p < 0.01), which is likely associated with a previously reported inverse relationship between temperatures and the on-shelf primary production. An analysis of the δ18O in the shells shows that the main growing season of the shells presumably occurs during the spring and summer months, which concurs with the main spring bloom.

  6. Relationships between Charpy impact shelf energies and upper shelf Ksub(IC) values for reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Witt, F.J.

    1983-01-01

    Charpy shelf data and lower bound estimates of Ksub(IC) shelf data for the same steels and test temperatures are given. Included are some typical reactor pressure vessel steels as well as some less tough or degraded steels. The data were evaluated with shelf estimates of Ksub(IC) up to and exceeding 550 MPa√m. It is shown that the high shelf fracture toughness representative of tough reactor pressure vessel steels may be obtained from a knowledge of the Charpy shelf energies. The toughness transition may be obtained either by testing small fracture toughness specimens or by Charpy energy indexing. (U.K.)

  7. 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.

  8. Nature of the observed oscillatory flows in shelf waters of the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Antony, M.K.; Sundar, D.

    of internal waves with frequencies close to semidiurnal period (internal tide) controlling the flow structure. The temperature records at these levels together with the B.T. time series data collected in the vicinity of mooring site supported the presence...

  9. Regional geochemical baselines for Portuguese shelf sediments

    International Nuclear Information System (INIS)

    Mil-Homens, M.; Stevens, R.L.; Cato, I.; Abrantes, F.

    2007-01-01

    Metal concentrations (Al, Cr, Cu, Ni, Pb and Zn) from the DGM-INETI archive data set have been examined for sediments collected during the 1970s from 267 sites on the Portuguese shelf. Due to the differences in the oceanographic and sedimentological settings between western and Algarve coasts, the archive data set is split in two segments. For both shelf segments, regional geochemical baselines (RGB) are defined using aluminium as a reference element. Seabed samples recovered in 2002 from four distinct areas of the Portuguese shelf are superimposed on these models to identify and compare possible metal enrichments relative to the natural distribution. Metal enrichments associated with anthropogenic influences are identified in three samples collected nearby the Tejo River and are characterised by the highest enrichment factors (EF; EF Pb Zn < 4). EF values close to 1 suggest a largely natural origin for metal distributions in sediments from the other areas included in the study. - Background metal concentrations and their natural variability must be established before assessing anthropogenic impacts

  10. Water

    Science.gov (United States)

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  11. Propagation of inertial-gravity waves on an island shelf

    Science.gov (United States)

    Bondur, V. G.; Sabinin, K. D.; Grebenyuk, Yu. V.

    2015-09-01

    The propagation of inertial-gravity waves (IGV) at the boundary of the Pacific shelf near the island of Oahu (Hawaii), whose generation was studied in the first part of this work [1], is analyzed. It is shown that a significant role there is played by the plane oblique waves; whose characteristics were identified by the method of estimating 3D wave parameters for the cases when the measurements are available only for two verticals. It is established that along with the descending propagation of energy that is typical of IGVs, wave packets ascend from the bottom to the upper layers, which is caused by the emission of waves from intense jets of discharged waters flowing out of a diffusor located at the bottom.

  12. Influence of volcanic history on groundwater patterns on the west slope of the Oregon High Cascades.

    Science.gov (United States)

    A. Jefferson; G. Grant; T. Rose

    2006-01-01

    Spring systems on the west slope of the Oregon High Cascades exhibit complex relationships among modern topography, lava flow geometries, and groundwater flow patterns. Seven cold springs were continuously monitored for discharge and temperature in the 2004 water year, and they were periodically sampled for ?18O, ?D, tritium, and dissolved noble gases. Anomalously high...

  13. Calculations of physical and chemical reactions with DNA in aqueous solution from Auger cascades

    International Nuclear Information System (INIS)

    Wright, H.A.; Hamm, R.N.; Turner, J.E.; Howell, R.W.; Rao, D.V.; Sastry, K.S.R.

    1989-01-01

    Monte Carlo calculations are performed of the physical and chemical interactions in liquid water by electrons produced during Auger cascades resulting from the decay of various radionuclides. Estimates are also made of the number of direct physical and indirect chemical interactions that would be produced on DNA located near the decay site. 13 refs., 8 figs

  14. Numerical routine for magnetic heat pump cascading

    DEFF Research Database (Denmark)

    Filonenko, Konstantin; Lei, Tian; Engelbrecht, Kurt

    Heat pumps use low-temperature heat absorbed from the energy source to create temperature gradient (TG) across the energy sink. Magnetic heat pumps (MHP) can perform this function through operating active magnetic regeneration (AMR) cycle. For building heating, TGs of up to a few K might...... and 3 K. Changing the number of MHPs, we optimized input parameters to achieve maximum heating powers. We have found that both maximum heating power and COP decrease together with number of heat pumps, but the TGs and the temperature span can be largely increased. References [1] M. Tahavori et al., “A...... be necessary, which is hardly achievable with a single MHP and such techniques as cascading are required. Series and parallel cascading increase the AMR span and heating power, respectively, but do not change TG. Therefore, the intermediate type of cascading was proposed with individual MHPs separately...

  15. Non-spill control squared cascade

    International Nuclear Information System (INIS)

    Kai, Tsunetoshi; Inoue, Yoshiya; Oya, Akio; Suemori, Nobuo.

    1974-01-01

    Object: To reduce a mixed loss thus enhancing separating efficiency by the provision of a simple arrangement wherein a reflux portion in a conventional spill control squared cascade is replaced by a special stage including centrifugal separators. Structure: Steps in the form of a square cascade, in which a plurality of centrifugal separators are connected by pipe lines, are accumulated in multistage fashion to form a squared cascade. Between the adjoining steps is disposed a special stage including a centrifugal separator which receives both lean flow from the upper step and rich flow from the lower step. The centrifugal separator in the special stage has its rich side connected to the upper step and its lean side connected to the lower step. Special stages are each disposed at the upper side of the uppermost step and at the lower side of the lowermost step. (Kamimura, M.)

  16. Sample Selection for Training Cascade Detectors.

    Science.gov (United States)

    Vállez, Noelia; Deniz, Oscar; Bueno, Gloria

    2015-01-01

    Automatic detection systems usually require large and representative training datasets in order to obtain good detection and false positive rates. Training datasets are such that the positive set has few samples and/or the negative set should represent anything except the object of interest. In this respect, the negative set typically contains orders of magnitude more images than the positive set. However, imbalanced training databases lead to biased classifiers. In this paper, we focus our attention on a negative sample selection method to properly balance the training data for cascade detectors. The method is based on the selection of the most informative false positive samples generated in one stage to feed the next stage. The results show that the proposed cascade detector with sample selection obtains on average better partial AUC and smaller standard deviation than the other compared cascade detectors.

  17. Sample Selection for Training Cascade Detectors.

    Directory of Open Access Journals (Sweden)

    Noelia Vállez

    Full Text Available Automatic detection systems usually require large and representative training datasets in order to obtain good detection and false positive rates. Training datasets are such that the positive set has few samples and/or the negative set should represent anything except the object of interest. In this respect, the negative set typically contains orders of magnitude more images than the positive set. However, imbalanced training databases lead to biased classifiers. In this paper, we focus our attention on a negative sample selection method to properly balance the training data for cascade detectors. The method is based on the selection of the most informative false positive samples generated in one stage to feed the next stage. The results show that the proposed cascade detector with sample selection obtains on average better partial AUC and smaller standard deviation than the other compared cascade detectors.

  18. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim

    2002-01-01

    In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage......-source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3 p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to 4 levels and low dv/dt, balanced operation of the inverter modules, each supplying a third...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...

  19. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Differential use of the Argentine shelf by wintering adults and juveniles southern giant petrels, Macronectes giganteus, from Patagonia

    Science.gov (United States)

    Blanco, Gabriela S.; Quintana, Flavio

    2014-08-01

    To study habitat use and at-sea movements of southern giant petrels (SGP) during non-breeding period, we deployed 15 satellite transmitters (six adults, nine juveniles) at Isla Arce and Isla Gran Robredo colonies in Patagonia, Argentina. Birds were instrumented during 81.4 ± 37 days. Adult birds used 74% of the Argentine shelf concentrating mainly at the shelf break, middle shelf waters, and the surroundings of the colony. After fledging, juveniles spread to the Argentine, Uruguayan and Brazilian shelves within the South Atlantic. Adults alternated at-sea excursions (12 ± 5 days) with periods at the colony of 3 ± 0.3 days. Contrarily, juveniles moved first to the shelf break and then traveled northwards reaching the south of Brazil. There was some spatial overlap between age classes, but only during the first 30 days after juveniles had fledged; thereafter there was not overlap between the areas used by both age classes. The Argentine shelf is widely used by different species offering a suitable environment for foraging; this may be why adults SGP from Patagonian colonies spend all year-round within the Argentine shelf. The identification of used areas of non-breeding SGP fills a gap in the species knowledge contributing not only to the preservation the species, but also to the management of marine areas globally recognized as important for many other Procellariiformes.

  1. Acoustic Doppler Current Profiler observations in the southern Caspian Sea: shelf currents and flow field off Feridoonkenar Bay, Iran

    Directory of Open Access Journals (Sweden)

    P. Ghaffari

    2010-07-01

    Full Text Available The results of offshore bottom-mounted ADCP measurements and wind records carried out from August to September 2003 in the coastal waters off Feridoon-kenar Bay (FB in the south Caspian Sea (CS are examined in order to characterize the shelf motion, the steady current field and to determine the main driving forces of currents on the study area. Owing to closed basin and absence of the astronomical tide, the atmospheric forcing plays an important role in the flow field of the CS. The lasting regular sea breeze system is present almost throughout the year. This system performs the forcing in diurnal and semi-diurnal bands similar to tides in other regions. In general, current field in the continental shelf could be separated into two distinguishable schemes, which in cross-shelf direction is dominated by high frequencies (1 cpd and higher frequencies, and in along-shelf orientation mostly proportional to lower frequencies in synoptic weather bands. Long-period wave currents, whose velocities are much greater than those of direct wind-induced currents, dominates the current field in the continental shelf off FB. The propagation of the latter could be described in terms of shore-controlled waves that are remotely generated and travel across the shelf in the southern CS. It has also been shown that long term displacements in this area follow the classic cyclonic, circulation pattern in the southern CS.

  2. A laboratory scale model of abrupt ice-shelf disintegration

    Science.gov (United States)

    Macayeal, D. R.; Boghosian, A.; Styron, D. D.; Burton, J. C.; Amundson, J. M.; Cathles, L. M.; Abbot, D. S.

    2010-12-01

    An important mode of Earth’s disappearing cryosphere is the abrupt disintegration of ice shelves along the Peninsula of Antarctica. This disintegration process may be triggered by climate change, however the work needed to produce the spectacular, explosive results witnessed with the Larsen B and Wilkins ice-shelf events of the last decade comes from the large potential energy release associated with iceberg capsize and fragmentation. To gain further insight into the underlying exchanges of energy involved in massed iceberg movements, we have constructed a laboratory-scale model designed to explore the physical and hydrodynamic interactions between icebergs in a confined channel of water. The experimental apparatus consists of a 2-meter water tank that is 30 cm wide. Within the tank, we introduce fresh water and approximately 20-100 rectangular plastic ‘icebergs’ having the appropriate density contrast with water to mimic ice. The blocks are initially deployed in a tight pack, with all blocks arranged in a manner to represent the initial state of an integrated ice shelf or ice tongue. The system is allowed to evolve through time under the driving forces associated with iceberg hydrodynamics. Digitized videography is used to quantify how the system of plastic icebergs evolves between states of quiescence to states of mobilization. Initial experiments show that, after a single ‘agitator’ iceberg begins to capsize, an ‘avalanche’ of capsizing icebergs ensues which drives horizontal expansion of the massed icebergs across the water surface, and which stimulates other icebergs to capsize. A surprise initially evident in the experiments is the fact that the kinetic energy of the expanding mass of icebergs is only a small fraction of the net potential energy released by the rearrangement of mass via capsize. Approximately 85 - 90 % of the energy released by the system goes into water motion modes, including a pervasive, easily observed seich mode of the tank

  3. Conditions Affecting Shelf-Life of Inoculated Legume Seed

    Directory of Open Access Journals (Sweden)

    Greg Gemell

    2012-02-01

    Full Text Available Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and soil but seed inoculation is the most economical technique. Large quantities of pasture seed in Australia are inoculated by commercial seed coating companies, but the long-term survival of seed-applied inoculum is variable and monitoring of viability requires specialist microbiology skills and facilities. The aim of our research was to define optimum storage conditions for survival of rhizobia on legume seed and evaluate water activity as a means of monitoring shelf-life. The relationship between survival and water activity varied according to seed species, inoculum preparation, coating ingredients, initial water activity and time suggesting that storage conditions would need to be defined for each different combination. Although drying seeds after coating significantly reduced viable numbers of rhizobia, survival of rhizobia on dried commercially coated lucerne seed after 11 weeks was less variable than seeds that had not been dried. The highest numbers were maintained when seeds remained dry with water activities of between 0.47 and 0.38. The quality of inoculated seed could be improved by reducing the death rate of inoculum during preparation and providing optimum storage conditions for long-term survival.

  4. Cascade Processes in Muonic Hydrogen Atoms

    International Nuclear Information System (INIS)

    Faifman, M. P.; Men'Shikov, L. I.

    2001-01-01

    The QCMC scheme created earlier for cascade calculations in heavy hadronic atoms of hydrogen isotopes has been modified and applied to the study of cascade processes in the μp muonic hydrogen atoms. The distribution of μp atoms over kinetic energies has been obtained and the yields of K-series X-rays per one stopped muon have been calculated.Comparison with experimental data indicated directly that for muonic and pionic atoms new types of non-radiative transitions are essential, while they are negligible for heavy (kaonic, antiprotonic, etc.) atoms. These processes have been considered and their probabilities have been estimated.

  5. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Benjamin

    2017-01-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  6. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael P.; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Ben

    2017-08-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  7. Interferometric modulation of quantum cascade interactions

    Science.gov (United States)

    Cusumano, Stefano; Mari, Andrea; Giovannetti, Vittorio

    2018-05-01

    We consider many-body quantum systems dissipatively coupled by a cascade network, i.e., a setup in which interactions are mediated by unidirectional environmental modes propagating through a linear optical interferometer. In particular we are interested in the possibility of inducing different effective interactions by properly engineering an external dissipative network of beam splitters and phase shifters. In this work we first derive the general structure of the master equation for a symmetric class of translation-invariant cascade networks. Then we show how, by tuning the parameters of the interferometer, one can exploit interference effects to tailor a large variety of many-body interactions.

  8. Inverse energy cascade and emergence of large coherent vortices in turbulence driven by Faraday waves.

    Science.gov (United States)

    Francois, N; Xia, H; Punzmann, H; Shats, M

    2013-05-10

    We report the generation of large coherent vortices via inverse energy cascade in Faraday wave driven turbulence. The motion of floaters in the Faraday waves is three dimensional, but its horizontal velocity fluctuations show unexpected similarity with two-dimensional turbulence. The inverse cascade is detected by measuring frequency spectra of the Lagrangian velocity, and it is confirmed by computing the third moment of the horizontal velocity fluctuations. This is observed in deep water in a broad range of wavelengths and vertical accelerations. The results broaden the scope of recent findings on Faraday waves in thin layers [A. von Kameke et al., Phys. Rev. Lett. 107, 074502 (2011)].

  9. The Columbia River plume as cross-shelf exporter and along-coast barrier

    Science.gov (United States)

    Banas, N. S.; MacCready, P.; Hickey, B. M.

    2009-01-01

    An intensive Lagrangian particle-tracking analysis of the July 2004 upwelling period was conducted in a hindcast model of the US Pacific Northwest coast, in order to determine the effect of the Columbia River plume on the fate of upwelled water. The model, implemented using Regional Ocean Modeling System (ROMS), includes variable wind and atmospheric forcing, variable Columbia river flow, realistic boundary conditions from Navy Coastal Ocean Model (NCOM), and 10 tidal constituents. Model skill has been demonstrated in detail elsewhere [MacCready, P., Banas, N.S., Hickey, B.M., Dever, E.P., Liu, Y., 2008. A model study of tide- and wind-induced mixing in the Columbia River estuary and plume. Continental Shelf Research, this issue, doi:10.1016/j.csr.2008.03.015]. Particles were released in the Columbia estuary, along the Washington coastal wall, and along the model's northern boundary at 48°N. Particles were tracked in three dimensions, using both velocities from ROMS and a vertical random displacement representing turbulent mixing. When 25 h of upwelling flow is looped and particles tracked for 12 d, their trajectories highlight a field of transient eddies and recirculations on scales from 5 to 50 km both north and south of the Columbia. Not all of these features are caused by plume dynamics, but the presence of the plume increases the entrainment of inner-shelf water into them. The cumulative effect of the plume's interaction with these transient features is to increase cross-shelf dispersion: 25% more water is transported laterally past the 100 m isobath when river and estuarine effects are included than when they are omitted. This cross-shelf dispersion also disrupts the southward transport of water along the inner shelf that occurs in the model when the Columbia River is omitted. This second effect—increased retention of upwelled water on the Washington shelf—may be partly responsible for the regional-scale alongcoast gradient in chlorophyll biomass

  10. Flux of energy and essential elements through the continental shelf ecosystem. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Pomeroy, L.R.

    1981-11-30

    There are three distinct but not mutually exclusive areas of research in this contract, studies of intrusions of the west wall of the Gulf Stream onto the outer continental shelf, studies of the flux of materials across nearshore density fronts, and advances in understanding of the planktonic food web of the continental shelf. Studies of frontal events on the outer and inner continental shelf involve distinctive physical and chemical regimes and have proven to require distinctive biological approaches. The studies of the food web run through our work on both of the frontal regimes, but certain aspects have become subjects in their own right. We have developed a simulation model of the flux of energy through the continental shelf food web which we believe to be more realistic than previous ones of its type. We have examined several of the many roles of dissolved organic compounds in sea water which originate either from release by phytoplankton, digestive processes or metabolites of zooplankton, or extracellular digestion of microorganisms. Methods have been developed under this contract to measure both the chelating capacity of naturally occurring organic materials and the copper concentration in the water. It has been possible to characterize the effects, both toxic and stimulatory, of copper on photosynthesis of naturally occurring phytoplankton populations. It is possible to characterize in considerable detail the course of biological events associated with meanders of the Gulf Stream. We are now in a position to explain the limits to biological productivity of the outer continental shelf of the southeastern US and the reasons why that biological production moves through the food web in the characteristic way that it does.

  11. Probabilistic study of cascading failures in complex interdependent lifeline systems

    International Nuclear Information System (INIS)

    Hernandez-Fajardo, Isaac; Dueñas-Osorio, Leonardo

    2013-01-01

    The internal complexity of lifeline systems and their standing interdependencies can operate in conjunction to amplify the negative effects of external disruptions. This paper introduces a simulation-based methodology to evaluate the joint impact of interdependence, component fragilities, and cascading failures in systemic fragility estimates. The proposed strategy uses a graph model of interdependent networks, an enhanced betweenness centrality for cascading failures approximation, and an interdependence model accounting for coupling uncertainty in the simulation of damage propagation for probabilistic performance assessment. This methodology is illustrated through its application to a realistic set of power and water networks subjected to earthquake scenarios and random failures. Test case results reveal two key insights: (1) the intensity of a perturbation influences interdependent systemic fragility by shaping the magnitudes of initial component damage and, sometimes counter-intuitively, the subsequent interdependence effects and (2) increasing local redundancy mitigates the effects of interdependence on systemic performance, but such intervention is incapable of eliminating interdependent effects completely. The previous insights provide basic guidelines for the design of systemic retrofitting policies. Additionally, the limitations of local capacity redundancy as a fragility control measure highlight the need for a critical assessment of intervention strategies in distributed infrastructure networks. Future work will assess the fragility-reduction efficiency of strategies involving informed manipulation of individual systemic topologies and the interdependence interfaces connecting them. - Highlights: ► An new simulation methodology effectively produces interdependent fragility assessments, IFAs. ► IFAs include perturbation action, cascading failures, and interdependent effects. ► Method tested using coupled networks exposed to earthquake and random

  12. Tracing river runoff and DOC over the East Siberian Shelf using in situ CDOM measurements

    Science.gov (United States)

    Pugach, Svetlana; Semiletov, Igor; Pipko, Irina

    2010-05-01

    The Great Siberian Rivers integrate meteorological and hydrological changes in their watersheds and play a significant role in the physical and biogeochemical regime of the Arctic Ocean through transport of fresh water (FW) and carbon into the sea. Since 1994, the Laboratory of Arctic Research POI in cooperation with the IARC UAF investigate the fresh water and carbon fluxes in the Siberian Arctic land-shelf system with the special emphasize in the East Siberian Arctic shelf (ESAS) which represents the widest and shallowest continental shelf in the World Ocean, yet it is still poorly explored. The East Siberian Sea is influenced by water exchange from the eastern Laptev Sea (where local shelf waters are diluted mostly by Lena River discharge) and by inflow of Pacific waters from the Chukchi Sea. This region is characterized by the highest rate of coastal erosion and significant volume of the riverine discharge and exhibits the largest gradients in all oceanographic parameters observed for the entire Arctic Ocean. Here we demonstrate a connection among Chromophoric (or Colored) Dissolved Organic Matter (CDOM) which represents the colored fraction of Dissolved Organic Carbon (DOC), salinity, and pCO2. Our data have documented strong linear correlations between salinity and CDOM in the near shore zone strongly influenced by riverine runoff. Correlation coefficient between CDOM and salinity in surface waters was equal to -0.94, -0.94 and -0.95 for surface water stations in September of 2003, 2004, and 2005, respectively. Combined analysis of CDOM and DOC data demonstrated a high degree of correlation between these parameters (r=0.96). Such close connection between these characteristics of waters in this region makes it possible to restore the distribution of DOC according to our original CDOM data of the profiling systems, such as CTD-Seabird equipped by WETStar CDOM fluorimeter. It is shown that the CDOM can be used as a conservative tracer to follow the transport and

  13. Ice-Shelf Melt Response to Changing Winds and Glacier Dynamics in the Amundsen Sea Sector, Antarctica

    Science.gov (United States)

    Donat-Magnin, Marion; Jourdain, Nicolas C.; Spence, Paul; Le Sommer, Julien; Gallée, Hubert; Durand, Gaël.

    2017-12-01

    It has been suggested that the coastal Southern Ocean subsurface may warm over the 21st century in response to strengthening and poleward shifting winds, with potential adverse effects on West Antarctic glaciers. However, using a 1/12° ocean regional model that includes ice-shelf cavities, we find a more complex response to changing winds in the Amundsen Sea. Simulated offshore subsurface waters get colder under strengthened and poleward shifted winds representative of the SAM projected trend. The buoyancy-driven circulation induced by ice-shelf melt transports this cold offshore anomaly onto the continental shelf, leading to cooling and decreased melt below 450 m. In the vicinity of ice-shelf fronts, Ekman pumping contributes to raise the isotherms in response to changing winds. This effect overwhelms the horizontal transport of colder offshore waters at intermediate depths (between 200 and 450 m), and therefore increases melt rates in the upper part of the ice-shelf cavities, which reinforces the buoyancy-driven circulation and further contributes to raise the isotherms. Then, prescribing an extreme grounding line retreat projected for 2100, the total melt rates simulated underneath Thwaites and Pine Island are multiplied by 2.5. Such increase is explained by a larger ocean/ice interface exposed to CDW, which is then amplified by a stronger melt-induced circulation along the ice draft. Our main conclusions are that (1) outputs from ocean models that do not represent ice shelf cavities (e.g., CMIP5 models) should not be directly used to predict the thermal forcing of future ice shelf cavities; (2) coupled ocean/ice sheet models with a velocity-dependent melt formulation are needed for future projections of glaciers experiencing a significant grounding line retreat.

  14. Evaluation of Power Generation Efficiency of Cascade Hydropower Plants: A Case Study

    Directory of Open Access Journals (Sweden)

    Jiahua Wei

    2013-02-01

    Full Text Available Effective utilization of scarce water resources has presented a significant challenge to respond to the needs created by rapid economic growth in China. In this study, the efficiency of the joint operation of the Three Gorges and Gezhouba cascade hydropower plants in terms of power generation was evaluated on the basis of a precise simulation-optimization technique. The joint operation conditions of the Three Gorges and Gezhouba hydropower plants between 2004 and 2010 were utilized in this research in order to investigate the major factors that could affect power output of the cascade complex. The results showed that the current power output of the Three Gorges and Gezhouba cascade complex had already reached around 90% of the maximum theoretical value. Compared to other influencing factors evaluated in this study, the accuracy of hydrological forecasts and flood control levels can have significant impact on the power generating efficiency, whereas the navigation has a minor influence. This research provides a solid quantitative-based methodology to assess the operation efficiency of cascade hydropower plants, and more importantly, proposes potential methods that could improve the operation efficiency of cascade hydropower plants.

  15. Shelf life extension of whole-wheat breadsticks: Formulation and packaging strategies.

    Science.gov (United States)

    Alamprese, Cristina; Cappa, Carola; Ratti, Simona; Limbo, Sara; Signorelli, Marco; Fessas, Dimitrios; Lucisano, Mara

    2017-09-01

    The aim of this study was the shelf life extension of whole-wheat breadsticks through the addition of a rosemary extract and packaging under nitrogen. Shelf life was studied at four temperatures (20, 27, 35, 48°C) for up to 200 storage days. The minimal changes observed in moisture, water activity and texture of the samples, coupled with the high peroxide values (13-539meqO 2 /kg fat ) measured at the end of storage, and the exponential increase of hexanal concentrations (up to 13-34mg/kg) confirmed that quality decay of whole-wheat breadsticks is mainly associated to lipid oxidation. The kinetic study of oxidation development and the consumer sensory acceptance determined by the survival analysis demonstrated that the rosemary extract addition yields a 42% shelf life extension, higher than that observed using nitrogen in the package (24-29%). The combination of the formulation and packaging strategies gave the best result (83% shelf life extension at 25°C). Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. NW Iberia Shelf Dynamics. Study of the Douro River Plume.

    Directory of Open Access Journals (Sweden)

    Isabel Iglesias

    2014-06-01

    Full Text Available River plumes are one of the most important mechanisms that transport the terrestrial materials to the coast and the ocean. Some examples of those materials are pollutants, essential nutrients, which enhance the phytoplankton productivity or sediments, which settle on the seabed producing modifications on the bathymetry affecting the navigation channels. The mixing between the riverine and the oceanic waters can induce instabilities, which might generate bulges, filaments, and buoyant currents over the continental shelf. Offshore, the buoyant riverine water could form a front with the oceanic waters often related with the occurrence of current-jets, eddies and strong mixing. The study and modelling of the river plumes is a key factor for the complete understanding of sediment transport mechanisms and patterns, and of coastal physics and dynamic processes. On this study the Douro River plume will be simulated. The Douro River is located on the north-west Iberian coast and its daily averaged freshwater discharge can range values from 0 to 13000 m3/s. This variability impacts the formation of the river plumes and its dispersion along the continental shelf. This study builds on the long-term objective of generate a Douro River plume forecasting system as part of the RAIA and RAIA.co projects. Satellite imagery was analyzed showing that the river Douro is one of the main sources of suspended particles, dissolved material and chlorophyll in the NW Iberian Shelf. The Regional Oceanic Modeling System (ROMS model was selected to reproduce scenarios of plume generation, retention and dispersion. Whit this model, three types of simulations were performed: (i schematic winds simulations with prescribed river flow, wind speed and direction; (ii multi-year climatological simulation, with river flow and temperature change for each month; (iii extreme case simulation, based on the Entre-os-Rios accident situation. The schematic wind case-studies suggest that the

  17. Direct observations of American eels migrating across the continental shelf to the Sargasso Sea.

    Science.gov (United States)

    Béguer-Pon, Mélanie; Castonguay, Martin; Shan, Shiliang; Benchetrit, José; Dodson, Julian J

    2015-10-27

    Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues.

  18. Physico-chemical properties of ready to eat, shelf-stable pasta during storage.

    Science.gov (United States)

    Carini, E; Curti, E; Cassotta, F; Najm, N E O; Vittadini, E

    2014-02-01

    The changes in physico-chemical properties of RTE shelf stable pasta were studied during storage with a multianalytical and multidimensional approach (with special focus on water status) to understand the ageing process in this product. Pasta hardness and amylopectin recrystallisation increased, macroscopic water status indicators and proton molecular translational mobility remained constant, and significant changes were measured in the proton rotational molecular mobility indicators ((1)H FID, (1)H T2) during storage. Since the main changes observed in RTE pasta during storage were similar to those observed in other cereal-based products, it would be interesting to verify the effect of the anti-staling methods commonly used in the cereal processing industry in improving RTE pasta shelf-stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Cascade reservoir flood control operation based on risk grading and warning in the Upper Yellow River

    Science.gov (United States)

    Xuejiao, M.; Chang, J.; Wang, Y.

    2017-12-01

    Flood risk reduction with non-engineering measures has become the main idea for flood management. It is more effective for flood risk management to take various non-engineering measures. In this paper, a flood control operation model for cascade reservoirs in the Upper Yellow River was proposed to lower the flood risk of the water system with multi-reservoir by combining the reservoir flood control operation (RFCO) and flood early warning together. Specifically, a discharge control chart was employed to build the joint RFCO simulation model for cascade reservoirs in the Upper Yellow River. And entropy-weighted fuzzy comprehensive evaluation method was adopted to establish a multi-factorial risk assessment model for flood warning grade. Furthermore, after determining the implementing mode of countermeasures with future inflow, an intelligent optimization algorithm was used to solve the optimization model for applicable water release scheme. In addition, another model without any countermeasure was set to be a comparative experiment. The results show that the model developed in this paper can further decrease the flood risk of water system with cascade reservoirs. It provides a new approach to flood risk management by coupling flood control operation and flood early warning of cascade reservoirs.

  20. Deuterium values from volcanic glass: A paleoelevation proxy for Oregon's Cascade Range

    Science.gov (United States)

    Carlson, T. B.; Bershaw, J. T.

    2016-12-01

    Hydrated volcanic glass has been used as a proxy to constrain Cenozoic paleoclimate across many of the world's mountain ranges. However, there are concerns that volcanic glass may not preserve the isotopic composition of syndepositional meteoric water. The Cascades are an excellent location to study the validity of hydrated volcanic glass as a paleoenvironmental proxy for several reasons. Moisture is derived from a single oceanic source and falls as orographic precipitation in the Cascades, leading to a characteristic altitude effect, or inverse relationship between elevation and the isotopic composition of meteoric water (δD). In addition, past studies have inferred uplift of the Cascades and an increase in the rain shadow effect since the Eocene through independent methods such as changing fossil assemblages, and other isotopic proxies including carbonates and fossil teeth. In this study, δD values of two hydrated tuff samples are compared: one prior to ( 29 Ma) and one following ( 5 Ma) the onset of High Cascade volcanism. The isotopic composition of these samples are interpreted in the context of modern water across the range to understand the potential of volcanic glass as a proxy for paleoelevation in the Pacific Northwest.

  1. Cascading effects of overfishing marine systems

    NARCIS (Netherlands)

    Scheffer, M.; Carpenter, S.; Young, de B.

    2005-01-01

    Profound indirect ecosystem effects of overfishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food

  2. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie; Danquah, Agyemang; Zé licourt, Axel de; Hirt, Heribert; Colcombet, Jean

    2015-01-01

    rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests

  3. Computer simulation of high energy displacement cascades

    International Nuclear Information System (INIS)

    Heinisch, H.L.

    1990-01-01

    A methodology developed for modeling many aspects of high energy displacement cascades with molecular level computer simulations is reviewed. The initial damage state is modeled in the binary collision approximation (using the MARLOWE computer code), and the subsequent disposition of the defects within a cascade is modeled with a Monte Carlo annealing simulation (the ALSOME code). There are few adjustable parameters, and none are set to physically unreasonable values. The basic configurations of the simulated high energy cascades in copper, i.e., the number, size and shape of damage regions, compare well with observations, as do the measured numbers of residual defects and the fractions of freely migrating defects. The success of these simulations is somewhat remarkable, given the relatively simple models of defects and their interactions that are employed. The reason for this success is that the behavior of the defects is very strongly influenced by their initial spatial distributions, which the binary collision approximation adequately models. The MARLOWE/ALSOME system, with input from molecular dynamics and experiments, provides a framework for investigating the influence of high energy cascades on microstructure evolution. (author)

  4. Energy Cascade in Fermi-Pasta Models

    Science.gov (United States)

    Ponno, A.; Bambusi, D.

    We show that, for long-wavelength initial conditions, the FPU dynamics is described, up to a certain time, by two KdV-like equations, which represent the resonant Hamiltonian normal form of the system. The energy cascade taking place in the system is then quantitatively characterized by arguments of dimensional analysis based on such equations.

  5. Molecular dynamics studies of displacement cascades

    International Nuclear Information System (INIS)

    Averback, R.S.; Hsieh, Horngming; Diaz de la Rubia, T.

    1990-02-01

    Molecular-dynamics simulations of cascades in Cu and Ni with primary-knock-on energies up to 5 keV and lattice temperatures in the range 0 K--700 K are described. Interatomic forces were represented by either the Gibson II (Cu) or Johnson-Erginsoy (Ni) potentials in most of this work, although some simulations using ''Embedded Atom Method'' potentials, e.g., for threshold events in Ni 3 Al, are also presented. The results indicate that the primary state of damage produced by displacement cascades is controlled by two phenomena, replacement collision sequences during the collisional phase of the cascade and local melting during the thermal spike. As expected, the collisional phase is rather similar in Cu and Ni, however, the thermal spike is of longer duration and has a more pronounced influence in Cu than Ni. When the ambient temperature of the lattice is increased, the melt zones are observed to both increase in size and cool more slowly. This has the effect of reducing defect production and enhancing atomic mixing and disordering. The implications of these results for defect production, cascade collapse, atomic disordering will be discussed. 34 refs., 7 figs., 2 tabs

  6. Impedance interactions in bidirectional cascaded converter

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Chen, Zhe

    2016-01-01

    A cascaded converter is built by connecting one elementary converter to another. Output impedance of one converter will therefore interact with input impedance of the other converter. This interaction will change when power flow reverses. To compare this difference, an investigation is performed...

  7. Forecasting Social Unrest Using Activity Cascades.

    Science.gov (United States)

    Cadena, Jose; Korkmaz, Gizem; Kuhlman, Chris J; Marathe, Achla; Ramakrishnan, Naren; Vullikanti, Anil

    2015-01-01

    Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011) to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach.

  8. Forecasting Social Unrest Using Activity Cascades.

    Directory of Open Access Journals (Sweden)

    Jose Cadena

    Full Text Available Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011 to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach.

  9. Gene regulation by MAP kinase cascades

    DEFF Research Database (Denmark)

    Fiil, Berthe Katrine; Petersen, Klaus; Petersen, Morten

    2009-01-01

    Mitogen-activated protein kinase (MAPK) cascades are signaling modules that transduce extracellular stimuli to a range of cellular responses. Research in yeast and metazoans has shown that MAPK-mediated phosphorylation directly or indirectly regulates the activity of transcription factors. Plant ...

  10. The Attention Cascade Model and Attentional Blink

    Science.gov (United States)

    Shih, Shui-I

    2008-01-01

    An attention cascade model is proposed to account for attentional blinks in rapid serial visual presentation (RSVP) of stimuli. Data were collected using single characters in a single RSVP stream at 10 Hz [Shih, S., & Reeves, A. (2007). "Attentional capture in rapid serial visual presentation." "Spatial Vision", 20(4), 301-315], and single words,…

  11. Cascaded FSO-VLC Communication System

    KAUST Repository

    Gupta, Akash; Sharma, Nikhil; Garg, Parul; Alouini, Mohamed-Slim

    2017-01-01

    The proposed cascaded free space optics (FSO)-visible light communication (VLC) system consists of multiple VLC access points which caters the end users connected via a decode and forward (DF) relay to the FSO backhaul link. The FSO link is assumed

  12. A simple method for potential flow simulation of cascades

    Indian Academy of Sciences (India)

    vortex panel method to simulate potential flow in cascades is presented. The cascade ... The fluid loading on the blades, such as the normal force and pitching moment, may ... of such discrete infinite array singularities along the blade surface.

  13. Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

    Directory of Open Access Journals (Sweden)

    J. T. Mathis

    2010-05-01

    Full Text Available In order to assess the current state of net community production (NCP in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmoles kg−1 over the inner shelf to ~2400 μmoles kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt, terrestrial inputs, and primary production. Concentrations were found to be as low ~1800 μmoles kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmoles kg−1 in the upper 30 m of the water column due to primary production and calcium carbonate formation between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of NCP on the inner, middle, and outer shelf averaged 28 ± 9 mmoles C m−2 d−1. However, higher rates of NCP (40–47 mmoles C m−2 d−1 were observed in the "Green Belt" where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total NCP across the shelf was on the order of ~96 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

  14. Glacial morphology and depositional sequences of the Antarctic Continental Shelf

    Science.gov (United States)

    ten Brink, Uri S.; Schneider, Christopher

    1995-01-01

    Proposes a simple model for the unusual depositional sequences and morphology of the Antarctic continental shelf. It considers the regional stratal geometry and the reversed morphology to be principally the results of time-integrated effects of glacial erosion and sedimentation related to the location of the ice grounding line. The model offers several guidelines for stratigraphic interpretation of the Antarctic shelf and a Northern Hemisphere shelf, both of which were subject to many glacial advances and retreats. -Authors

  15. 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

  16. Cascade theory in isotopic separation processes; Theorie des cascades en separation isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, J P

    1994-06-01

    Three main areas are developed within the scope of this work: - the first one is devoted to fundamentals: separative power, value function, ideal cascade and square cascade. Applications to two main cases are carried out, namely: Study of binary isotopic mix, Study of processes with a small enrichment coefficient. - The second one is devoted to cascade coupling -high-flux coupling (more widely used and better known) as well as low-flux coupling are presented and compared to one another. - The third one is an outlook on problems linked to cascade transients. Those problem are somewhat intricate and their interest lies mainly into two areas: economics where the start-up time may have a large influence on the interests paid during the construction and start-up period, military productions where the start-up time has a direct bearing on the production schedule. (author). 50 figs. 3 annexes. 12 refs. 6 tabs.

  17. Ecological and taphonomical influences on coccoliths in surface sediments in the shelf of the Yellow and East China Seas

    Science.gov (United States)

    Jin, Xiaobo; Liu, Chuanlian

    2017-05-01

    Coccoliths, combined with sediment grain size, carbonate calcium and organic matters content, were analyzed to assess the ecological and taphonomical influences on coccolith distribution patterns in surface sediments in the continental shelf of the Yellow and East China Seas. Coccolith abundances ranged from 0 to 2.08×109 coccoliths g-1 sediment. The increasing abundance from the coastal inner shelf to the seaward middle shelf generally reflects the ecological fact that living coccolithophores are more abundant in the mesotrophic shelf waters than in the eutrophic coastal waters, although their deposits are still controlled by taphonomical effects, such as bottom (tidal) currents and calcite preservation conditions. Most abundant coccoliths are found in the fine-grained sediments of southwestern Cheju Island, where both ecology and taphonomy favor coccolith preservation. Still, large densities of coccoliths (>108 coccoliths g-1 sediment) are also found in coarse-grained relict sediments in the middle shelf. Coccolith assemblages were predominated by Gephyrocapsa oceanica and Emiliania huxleyi. The relative abundance of E. huxleyi, in addition to ecological reasons, may relate to selective post-mortem dissolution, since small E. huxleyi coccoliths are more susceptible to dissolution. Coccolith calcite has minor contributions (<1% to 12%) to total sediment CaCO3, and the main parts are attributed to terrigenous CaCO3 debris and relict shell fragments.

  18. Particle fluxes in atomic collision cascades

    International Nuclear Information System (INIS)

    Sckerl, B.W.; Sigmund, P.; Vicanek, M.

    1996-01-01

    The flux of recoil atoms in atomic collision cascades induced by an ion beam or another source of energetic particles in a material is known to approach isotropy at kinetic energies far below the beam energy. A variety of irradiation effects can be explained satisfactorily on the basis of an isotropic particle flux, but significant deviations from this simple behavior are known to exist. While numerous examples have been studied by numerical simulation of cascade processes, the systematics is, by and large, unknown. The present study aims at general scaling properties and estimates of the magnitude of moderate deviations from isotropy and their spatial dependence for a wide range of beam and material parameters. Anisotropies introduced by crystal structure are ignored. Although it is well established that cascade anisotropy is related to the momentum of beam particles, previous attempts to quantify this relation have failed. We have found that there are two leading correction terms to the isotropic particle flux, a well-known term centered around the beam direction as a symmetry axis and a new term proportional to the gradient of the deposited-energy density. As a general rule the two contributions are either both significant or both negligible. Specific situations in which the gradient term dominates are, however, of considerable interest in applications. The parameters which characterize the anisotropy of collision cascades also determine the deposition of momentum, but the connection is less straightforward than asserted hitherto. General principles are first illustrated on the specific case of elastic-collision cascades under self-bombardment which contains the essentials. Thereafter several generalizations are made, including atomic binding forces and inelasticity as well as allowance for multicomponent materials. Application areas in mixing and sputtering are outlined. (au) 58 refs

  19. Cascading Generative Adversarial Networks for Targeted

    KAUST Repository

    Hamdi, Abdullah

    2018-01-01

    Abundance of labelled data played a crucial role in the recent developments in computer vision, but that faces problems like scalability and transferability to the wild. One alternative approach is to utilize the data without labels, i.e. unsupervised learning, in learning valuable information and put it in use to tackle vision problems. Generative Adversarial Networks (GANs) have gained momentum for their ability to model image distributions in unsupervised manner. They learn to emulate the training set and that enables sampling from that domain and using the knowledge learned for useful applications. Several methods proposed enhancing GANs, including regularizing the loss with some feature matching. We seek to push GANs beyond the data in the training and try to explore unseen territory in the image manifold. We first propose a new regularizer for GAN based on K-Nearest Neighbor (K-NN) selective feature matching to a target set Y in high-level feature space, during the adversarial training of GAN on the base set X, and we call this novel model K-GAN. We show that minimizing the added term follows from cross-entropy minimization between the distributions of GAN and set Y. Then, we introduce a cascaded framework for GANs that try to address the task of imagining a new distribution that combines the base set X and target set Y by cascading sampling GANs with translation GANs, and we dub the cascade of such GANs as the Imaginative Adversarial Network (IAN). Several cascades are trained on a collected dataset Zoo-Faces and generated innovative samples are shown, including from K-GAN cascade. We conduct an objective and subjective evaluation for different IAN setups in the addressed task of generating innovative samples and we show the effect of regularizing GAN on different scores. We conclude with some useful applications for these IANs, like multi-domain manifold traversing.

  20. Cascading Generative Adversarial Networks for Targeted

    KAUST Repository

    Hamdi, Abdullah

    2018-04-09

    Abundance of labelled data played a crucial role in the recent developments in computer vision, but that faces problems like scalability and transferability to the wild. One alternative approach is to utilize the data without labels, i.e. unsupervised learning, in learning valuable information and put it in use to tackle vision problems. Generative Adversarial Networks (GANs) have gained momentum for their ability to model image distributions in unsupervised manner. They learn to emulate the training set and that enables sampling from that domain and using the knowledge learned for useful applications. Several methods proposed enhancing GANs, including regularizing the loss with some feature matching. We seek to push GANs beyond the data in the training and try to explore unseen territory in the image manifold. We first propose a new regularizer for GAN based on K-Nearest Neighbor (K-NN) selective feature matching to a target set Y in high-level feature space, during the adversarial training of GAN on the base set X, and we call this novel model K-GAN. We show that minimizing the added term follows from cross-entropy minimization between the distributions of GAN and set Y. Then, we introduce a cascaded framework for GANs that try to address the task of imagining a new distribution that combines the base set X and target set Y by cascading sampling GANs with translation GANs, and we dub the cascade of such GANs as the Imaginative Adversarial Network (IAN). Several cascades are trained on a collected dataset Zoo-Faces and generated innovative samples are shown, including from K-GAN cascade. We conduct an objective and subjective evaluation for different IAN setups in the addressed task of generating innovative samples and we show the effect of regularizing GAN on different scores. We conclude with some useful applications for these IANs, like multi-domain manifold traversing.

  1. The potential for satellite and marginal field developments on the Norwegian continental shelf

    International Nuclear Information System (INIS)

    Raustein, O.; Abrahamsen, L.E.; Einang, G.

    1994-01-01

    Norway is faced with decreasing field sizes in hostile waters. On the other hand, approximately 620 billion 1993-NOK have been invested in field installations and transport systems. These installations will have significant available processing and transport capacity in the future, and thus represent a valuable infrastructure. This paper describes the resource situation and the installed infrastructure on the Norwegian Continental Shelf. Then the potential of still maintaining a high activity level in field developments is outlined

  2. Shelf-life and quality evaluation of clementine following a combined treatment with γ-irradiation

    International Nuclear Information System (INIS)

    Mahrouz, M.; Lacroix, M.; D'Aprano, G.; Oufedjikh, H.; Boubekri, C.

    2004-01-01

    In order to enhance the shelf-life of a late variety of Moroccan Citrus clementina (Nour), ionizing treatments were applied at 0.3 kGy, as well as washing (cold water) and waxing treatments. It has been found that, despite the irradiation treatment, the washing and waxing treatment do not improve the quality of C. clementina, but rather result in peel injury. Finally, sensory evaluation confirmed that irradiation had no detrimental effect on the quality of clementines

  3. Clay mineral distribution on tropical shelf: an example from the western shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Hashimi, N.H.; Nair, R.R.

    Seventy-five sediment samples collected from the Kerala continental shelf and slope during the 17th and 71st Cruises of RV Gaveshani were analysed by X-ray diffraction for clay mineral content. The distribution of total clay ( 4 mu fraction...

  4. Experimental study of a cascade solar still coupled with a humidification–dehumidification system

    International Nuclear Information System (INIS)

    Farshchi Tabrizi, Farshad; Khosravi, Meisam; Shirzaei Sani, Iman

    2016-01-01

    Graphical abstract: In this study, coupling of a cascade solar still with a humidification–dehumidification system investigated experimentally. In addition, the effects of different operating conditions and configurations on thermal performance and productivity of the under investigation solar system were studied. - Highlights: • We investigate coupling of a cascade solar still with a humidification–dehumidification system. • The effects of different operating conditions on thermal performance were studied. • Temperature and flow rate of feed water as well as air process flow rate had undeniable effects on the productivity. • Coupling several CSS systems with just one HD system to maximize the productivity. • Enhancing daily productivity of coupling system from 28% to 141% for 40–150 ml/min flow rates, respectively. - Abstract: In this study, coupling of a cascade solar still with a humidification–dehumidification system was investigated experimentally under the climatological conditions of Zahedan (Latitude: 29.49, Longitude: 60.87), Iran. The inclined solar stills produce distillated and hot water simultaneously. In addition, the effects of different operating conditions and configurations on thermal performance and productivity of the solar system were studied. The effect of feed water and air flow rates on the daily productivity of HD system in different conditions such as feed water temperature has been investigated. The daily productivity of cascade solar still with and without HD system at different flow rates is investigated. Moreover, the end result of assembling the HD system with a cascade solar still was studied. The daily productivity of the system increases from 28% to 141% in the presence of humidification–dehumidification system. It also improves the thermal efficiency from 9% to 20% after using 40–150 ml/min of flow rate, respectively. The maximum productivity and efficiency were 5.4 kg/m"2 day and 39% for minimum flow rate.

  5. Has spring snowpack declined in the Washington Cascades?

    Directory of Open Access Journals (Sweden)

    P. Mote

    2008-02-01

    Full Text Available Our best estimates of 1 April snow water equivalent (SWE in the Cascade Mountains of Washington State indicate a substantial (roughly 15–35% decline from mid-century to 2006, with larger declines at low elevations and smaller declines or increases at high elevations. This range of values includes estimates from observations and hydrologic modeling, reflects a range of starting points between about 1930 and 1970 and also reflects uncertainties about sampling. The most important sampling issue springs from the fact that half the 1 April SWE in the Cascades is found below about 1240 m, altitudes at which sampling was poor before 1945. Separating the influences of temperature and precipitation on 1 April SWE in several ways, it is clear that long-term trends are dominated by trends in temperature, whereas variability in precipitation adds "noise" to the time series. Consideration of spatial and temporal patterns of change rules out natural variations like the Pacific Decadal Oscillation as the sole cause of the decline. Regional warming has clearly played a role, but it is not yet possible to quantify how much of that regional warming is related to greenhouse gas emissions.

  6. Criticality safety concerns of uranium deposits in cascade equipment

    International Nuclear Information System (INIS)

    Plaster, M.J.

    1996-01-01

    The Paducah and Portsmouth Gaseous Diffusion Plants enrich uranium in the 235 U isotope by diffusing gaseous uranium hexafluoride (UF 6 ) through a porous barrier. The UF 6 gaseous diffusion cascade utilized several thousand open-quotes stagesclose quotes of barrier to produce highly enriched uranium (HEU). Historically, Portsmouth has enriched the Paducah Gaseous Diffusion Plant's product (typically 1.8 wt% 235 U) as well as natural enrichment feed stock up to 97 wt%. Due to the chemical reactivity of UF 6 , particularly with water, the formation of solid uranium deposits occur at a gaseous diffusion plant. Much of the equipment operates below atmospheric pressure, and deposits are formed when atmospheric air enters the cascade. Deposits may also be formed from UF 6 reactions with oil, UF 6 reactions with the metallic surfaces of equipment, and desublimation of UF 6 . The major deposits form as a result of moist air in leakage due to failure of compressor casing flanges, blow-off plates, seals, expansion joint convolutions, and instrument lines. This report describes criticality concerns and deposit disposition

  7. Using aerogravity and seismic data to model the bathymetry and upper crustal structure beneath the Pine Island Glacier ice shelf, West Antarctica

    Science.gov (United States)

    Muto, A.; Peters, L. E.; Anandakrishnan, S.; Alley, R. B.; Riverman, K. L.

    2013-12-01

    Recent estimates indicate that ice shelves along the Amundsen Sea coast in West Antarctica are losing substantial mass through sub-ice-shelf melting and contributing to the accelerating mass loss of the grounded ice buttressed by them. For Pine Island Glacier (PIG), relatively warm Circumpolar Deep Water has been identified as the key driver of the sub-ice-shelf melting although poor constraints on PIG sub-ice shelf have restricted thorough understanding of these ice-ocean interactions. Aerogravity data from NASA's Operation IceBridge (OIB) have been useful in identifying large-scale (on the order of ten kilometers) features but the results have relatively large uncertainties due to the inherent non-uniqueness of the gravity inversion. Seismic methods offer the most direct means of providing water thickness and upper crustal geological constraints, but availability of such data sets over the PIG ice shelf has been limited due to logistical constraints. Here we present a comparative analysis of the bathymetry and upper crustal structure beneath the ice shelf of PIG through joint inversion of OIB aerogravity data and in situ active-source seismic measurements collected in the 2012-13 austral summer. Preliminary results indicate improved resolution of the ocean cavity, particularly in the interior and sides of the PIG ice shelf, and sedimentary drape across the region. Seismically derived variations in ice and ocean water densities are also applied to the gravity inversion to produce a more robust model of PIG sub-ice shelf structure, as opposed to commonly used single ice and water densities across the entire study region. Misfits between the seismically-constrained gravity inversion and that estimated previously from aerogravity alone provide insights on the sensitivity of gravity measurements to model perturbations and highlight the limitations of employing gravity data to model ice shelf environments when no other sub-ice constraints are available.

  8. Seaweed culture and continental shelf protection

    Energy Technology Data Exchange (ETDEWEB)

    Przhemenetskaya, V F

    1985-07-01

    The initial impression that the resources of the oceans were limitless has been replaced by a more rational appreciation that everything has its limits, including the seemingly infinite resources of marine plant life. In addition, experience in California, Australia, China, Japan and Korea has demonstrated that depletion of seaweed resources for commercial utilization has a deleterious effect on the biocenotic status of the continental shelf. In view of this, many countries, such as Japan, China, Korea, the Philippines and the USSR, have embarked on aquaculture programs, in which seaweeds are cultivated on marine plantations. Successful developments in this direction should go a long way to preserving the natural ecologic balance on the continental shelf, and yet provide mankind with the resources of the deep. Many difficulties remain to be resolved before aquaculture programs become fully cost effective, one of which deals with the susceptibility of a monoculture to a given predator or disease. To that end, such programs necessitate the creation of well balanced systems that would support a variety of marine plant and animal life without an adverse effect on the desired crop. 4 references, 6 figures.

  9. MILK CANDIES WITH INCREASED SHELF LIFE

    Directory of Open Access Journals (Sweden)

    G. O. Magomedov

    2014-01-01

    Full Text Available Summary. Technology for producing milk candies on molasses with increased shelf-life, molded by "extrusion" with a vacuum syringe of continuous action used in the meat industry, into metallized film like "flow-pack" is considered. Rheological characteristics of candy mass: strength, toughness, organoleptic, physical and chemical quality are determined. While increasing the temperature of milk mass the colour, texture, mass fraction of reducing substances and solids change. It was found out that molasses based milk mass is easily molded at a moisture content of 10-11 % and temperature of 60 ºС. The advantages of the new method of forming products are: manufactured products have individual package, which increases the shelf life and improves the quality of products, extend the range of use, the technological equipment has a high productivity, it is compact and reliable. According to the consumer qualities the product surpasses all known analogs. Possibility of using a single-piece product while gathering dinners and breakfasts in public catering, establishments and transport. The technological process is simplified. Energy value of products on molasses in comparison with the control samples on sugar is calculated. It is 51 kcal less than in the control sample on sugar. Thus, the technology of functional milk candies with reduced sugar content is developed. The products will be useful for anyone who leads a healthy lifestyle.

  10. Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

    Directory of Open Access Journals (Sweden)

    A. Randelhoff

    2018-04-01

    Full Text Available The future of Arctic marine ecosystems has received increasing attention in recent years as the extent of the sea ice cover is dwindling. Although the Pacific and Atlantic inflows both import huge quantities of nutrients and plankton, they feed into the Arctic Ocean in quite diverse regions. The strongly stratified Pacific sector has a historically heavy ice cover, a shallow shelf and dominant upwelling-favourable winds, while the Atlantic sector is weakly stratified, with a dynamic ice edge and a complex bathymetry. We argue that shelf break upwelling is likely not a universal but rather a regional, albeit recurring, feature of the new Arctic. It is the regional oceanography that decides its importance through a range of diverse factors such as stratification, bathymetry and wind forcing. Teasing apart their individual contributions in different regions can only be achieved by spatially resolved time series and dedicated modelling efforts. The Northern Barents Sea shelf is an example of a region where shelf break upwelling likely does not play a dominant role, in contrast to the shallower shelves north of Alaska where ample evidence for its importance has already accumulated. Still, other factors can contribute to marked future increases in biological productivity along the Arctic shelf break. A warming inflow of nutrient-rich Atlantic Water feeds plankton at the same time as it melts the sea ice, permitting increased photosynthesis. Concurrent changes in sea ice cover and zooplankton communities advected with the boundary currents make for a complex mosaic of regulating factors that do not allow for Arctic-wide generalizations.

  11. Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

    Science.gov (United States)

    Randelhoff, Achim; Sundfjord, Arild

    2018-04-01

    The future of Arctic marine ecosystems has received increasing attention in recent years as the extent of the sea ice cover is dwindling. Although the Pacific and Atlantic inflows both import huge quantities of nutrients and plankton, they feed into the Arctic Ocean in quite diverse regions. The strongly stratified Pacific sector has a historically heavy ice cover, a shallow shelf and dominant upwelling-favourable winds, while the Atlantic sector is weakly stratified, with a dynamic ice edge and a complex bathymetry. We argue that shelf break upwelling is likely not a universal but rather a regional, albeit recurring, feature of the new Arctic. It is the regional oceanography that decides its importance through a range of diverse factors such as stratification, bathymetry and wind forcing. Teasing apart their individual contributions in different regions can only be achieved by spatially resolved time series and dedicated modelling efforts. The Northern Barents Sea shelf is an example of a region where shelf break upwelling likely does not play a dominant role, in contrast to the shallower shelves north of Alaska where ample evidence for its importance has already accumulated. Still, other factors can contribute to marked future increases in biological productivity along the Arctic shelf break. A warming inflow of nutrient-rich Atlantic Water feeds plankton at the same time as it melts the sea ice, permitting increased photosynthesis. Concurrent changes in sea ice cover and zooplankton communities advected with the boundary currents make for a complex mosaic of regulating factors that do not allow for Arctic-wide generalizations.

  12. Eddy-resolving simulations of the Fimbul Ice Shelf cavity circulation: Basal melting and exchange with open ocean

    Science.gov (United States)

    Hattermann, T.; Smedsrud, L. H.; Nøst, O. A.; Lilly, J. M.; Galton-Fenzi, B. K.

    2014-10-01

    Melting at the base of floating ice shelves is a dominant term in the overall Antarctic mass budget. This study applies a high-resolution regional ice shelf/ocean model, constrained by observations, to (i) quantify present basal mass loss at the Fimbul Ice Shelf (FIS); and (ii) investigate the oceanic mechanisms that govern the heat supply to ice shelves in the Eastern Weddell Sea. The simulations confirm the low melt rates suggested by observations and show that melting is primarily determined by the depth of the coastal thermocline, regulating deep ocean heat fluxes towards the ice. Furthermore, the uneven distribution of ice shelf area at different depths modulates the melting response to oceanic forcing, causing the existence of two distinct states of melting at the FIS. In the simulated present-day state, only small amounts of Modified Warm Deep Water enter the continental shelf, and ocean temperatures beneath the ice are close to the surface freezing point. The basal mass loss in this so-called state of "shallow melting" is mainly controlled by the seasonal inflow of solar-heated surface water affecting large areas of shallow ice in the upper part of the cavity. This is in contrast to a state of "deep melting", in which the thermocline rises above the shelf break depth, establishing a continuous inflow of Warm Deep Water towards the deep ice. The transition between the two states is found to be determined by a complex response of the Antarctic Slope Front overturning circulation to varying climate forcings. A proper representation of these frontal dynamics in climate models will therefore be crucial when assessing the evolution of ice shelf basal melting along this sector of Antarctica.

  13. Clay sediment accumulation rates on the monsoon-dominated western continental shelf and slope region of India

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    Clay accumulation rates shown in sediment cores from the nearshore to outer continental shelf and slope regions in water depths of 10-1246 m on the western continental margins of India were determined by the 210Pb dating technique. The 210Pb excess...

  14. Quantum Cascade Lasers Modulation and Applications

    Science.gov (United States)

    Luzhansky, Edward

    The mid-wave IR (MWIR) spectral band, extending from 3 to 5 microns, is considered to be a low loss atmospheric window. There are several spectral sub-bands with relatively low atmospheric attenuation in this region making it popular for various commercial and military applications. Relatively low thermal and solar background emissions, effective penetration through the natural and anthropogenic obscurants and eye safety add to the long list of advantages of MWIR wavelengths. Quantum Cascade Lasers are compact semiconductor devices capable of operating in MWIR spectrum. They are based on inter-subband transitions in a multiple-quantum-well (QW) hetero-structure, designed by means of band-structure engineering. The inter-subband nature of the optical transition has several key advantages. First, the emission wavelength is primarily a function of the QW thickness. This characteristic allows choosing well-understood and reliable semiconductors for the generation of light in a wavelength range of interest. Second, a cascade process in which tens of photons are generated per injected electron. This cascading process is behind the intrinsic high-power capabilities of QCLs. This dissertation is focused on modulation properties of Quantum Cascade Lasers. Both amplitude and phase/frequency modulations were studied including modulation bandwidth, modulation efficiency and chirp linearity. Research was consisted of the two major parts. In the first part we describe the theory of frequency modulation (FM) response of Distributed Feedback Quantum Cascade Lasers (DFB QCL). It includes cascading effect on the QCL's maximum modulation frequency. The "gain levering" effect for the maximum FM response of the two section QCLs was studied as well. In the second part of research we concentrated on the Pulse Position Amplitude Modulation of a single section QCL. The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept is

  15. Geoarchaeological response to landscape changes of the Greek continental shelf since the Last Glacial Maximum

    Science.gov (United States)

    Kapsimalis, Vasilios; Pavlopoulos, Kosmas; Panagiotopoulos, Ioannis

    2010-05-01

    ) archaeological data coming from, nowadays, coastal prehistoric sites; and (a) mythological references. At the Last Gracial Maximum, Palaeolithic human dispersed on the subaerially-exposed Greek shelf searching for places with mild climates, drinking water and food. When the sea-lever started to rise (ca. 18 kyr B.P.), people moved inland following some main migration routes on the North Aegean shelf, Thermaikos Gulf, Pagasitikos/North Evvoikos Gulf, Saronikos Gulf, Argolikos Gulf, Patrakos/Corinthian Gulf, and north Ionian shelf. Frequently, at the landward end of these routes, there are Mesolithic or Neolithic sites established when the sea level reached approximately its present position and preserved because coastal or marine processes did not destroyed them. Furthermore, the long-standing migration could be recorded in the social memory like a landward escapement from a destructive flood.

  16. The Cross Surfzone/Inner-shelf Dye Exchange (CSIDE) Experiment Overview: Binational Dye Tracer Releases to Study Pollution Transport and Dilution.

    Science.gov (United States)

    Feddersen, F.; Giddings, S. N.; Kumar, N.; Grimes, D. J.; Pawlak, G. R.; Rivas, D.; Diaz, M.

    2016-02-01

    Per square km, the surfzone and inner-shelf are by far the most economically and ecologically important ocean regions, vital for recreation, food, and ecosystem services. Despite the importance of clean coastal waters to our economy and well-being, declining water quality threatens coastal ecosystem and human health worldwide. Healthy coasts are a significant priority to federal agencies, local government, and NGOs. In particular the San Diego US and Tijuana Mexico border region have unique and persistent water quality issues due to a range of pollution sources. Cross-shore exchange of tracers (e.g., pathogens, anthropogenic nutrients, harmful algal blooms - HABs, larvae) between the well-mixed surfzone and stratified inner-shelf is poorly understood. The surfzone, inner- and mid-shelf span drastically different dynamical regimes, with varying cross-shelf exchange mechanisms due to wave, wind, buoyancy, and tidal processes and intrinsic variability. The NSF funded CSIDE (Cross Surfzone/Inner-shelf Dye Exchange) experiment (Sept & Oct 2015) aims to increase our understanding of cross-shelf material exchange by performing 3 shoreline dye release experiments that are tracked for up to 20 km alongshore and over 48+ hrs. One dye release will be performed in Mexico and the dye transport tracked across the border. The dye will be tracked via a broad range of binational instrumentation. In this presentation, we present an overview of the CSIDE experiment, in particular the binational aspects of the study,

  17. Outlet Glacier-Ice Shelf-Ocean Interactions: Is the Tail Wagging the Dog?

    Science.gov (United States)

    Parizek, B. R.; Walker, R. T.; Rinehart, S. K.

    2009-12-01

    While the massive interior regions of the Antarctic and Greenland Ice Sheets are presently ``resting quietly", the lower elevations of many outlet glaciers are experiencing dramatic adjustments due to changes in ice dynamics and/or surface mass balance. Oceanic and/or atmospheric forcing in these marginal regions often leads to mass deficits for entire outlet basins. Therefore, coupling the wagging tail of ice-ocean interactions with the vast ice-sheet reservoirs is imperative for accurate assessments of future sea-level rise. To study ice-ocean dynamic processes, we couple an ocean-plume model that simulates ice-shelf basal melting rates based on temperature and salinity profiles combined with plume dynamics associated with the geometry of the ice-shelf cavity (following Jenkins, 1991 and Holland and Jenkins, 1999) with a two-dimensional, isothermal model of outlet glacier-ice shelf flow (as used in Alley et al., 2007; Walker et al., 2008; Parizek et al., in review). Depending on the assigned temperature and salinity profiles, the ocean model can simulate both water-mass end-members: either cold High Salinity Shelf Water (HSSW) or relatively warm Circumpolar Deep Water (CDW), as well as between-member conditions. Notably, the coupled system exhibits sensitivity to the initial conditions. In particular, melting concentrated near the grounding line has the greatest effect in forcing grounding-line retreat. Retreat is further enhanced by a positive feedback between the ocean and ice, as the focused melt near the grounding line leads to an increase in the local slope of the basal ice, thereby enhancing buoyancy-driven plume flow and subsequent melt rates.

  18. Scheduling of head-sensitive cascaded hydro systems : a comparison based on numerical simulation results

    Energy Technology Data Exchange (ETDEWEB)

    Catalao, J.P.S.; Mariano, S.J.P.S. [Beira Interior Univ., Covilha (Portugal). Dept. of Electromechanical Engineering; Mendes, V.M.F. [Superior Engineering Inst. of Lisbon, Lisbon (Portugal). Dept. of Electrical Engineering and Automation; Ferreira, L.A.F.M. [Technical Univ. of Lisbon, Superior Technical Inst., Lisbon (Portugal). Dept. of Electrical Engineering and Computers

    2008-07-01

    The electric power sector in Portugal and Spain has shifted from a traditional monopoly to a deregulated, competitive energy market. As such, hydroelectric facilities face the optimal challenge of how to make a profit by managing water resources without compromising future potential profit. As such, hydro scheduling is a key activity for hydroelectric power utilities because of its significant economic impact. It involves the optimal management of water inflows and storage in reservoirs. This paper considered the problem of short-term hydro scheduling, concerning head-sensitive cascaded reservoirs, and the algorithmic aspects of its solution. The authors proposed and compared optimization methods based on dynamic programming, and linear and nonlinear network programming. The comparison revealed a negligible extra computational effort in a realistic cascaded hydro system where the head depended on the stored water volume. 17 refs., 3 tabs., 7 figs.

  19. Scheduling of head-sensitive cascaded hydro systems : a comparison based on numerical simulation results

    International Nuclear Information System (INIS)

    Catalao, J.P.S.; Mariano, S.J.P.S.; Mendes, V.M.F.; Ferreira, L.A.F.M.

    2008-01-01

    The electric power sector in Portugal and Spain has shifted from a traditional monopoly to a deregulated, competitive energy market. As such, hydroelectric facilities face the optimal challenge of how to make a profit by managing water resources without compromising future potential profit. As such, hydro scheduling is a key activity for hydroelectric power utilities because of its significant economic impact. It involves the optimal management of water inflows and storage in reservoirs. This paper considered the problem of short-term hydro scheduling, concerning head-sensitive cascaded reservoirs, and the algorithmic aspects of its solution. The authors proposed and compared optimization methods based on dynamic programming, and linear and nonlinear network programming. The comparison revealed a negligible extra computational effort in a realistic cascaded hydro system where the head depended on the stored water volume. 17 refs., 3 tabs., 7 figs

  20. Study on shelf life extension of papayas irradiated by /sup 60/Co gamma-rays

    Energy Technology Data Exchange (ETDEWEB)

    Chang, M.S.; Chen, M.D.; Lin, C.T.; Fu, Y.K.

    1984-11-01

    Papayas are one of the main fresh fruits in Taiwan area. Papaya fruits were treated with hot water to pasteurize peels followed by /sup 60/Co gamma-ray irradiation to extend the ripening time. The purpose of synergetic methods is to extend the shelf life of papaya fruits. This experiment was carried out by seven treatments, which were: (1) control group, (2) hot water treatment only, (3) hot water treatment with a 25 krad ..gamma..-irradiation, (4) hot water treatment with a 50 krad ..gamma..-irradiation, (5) hot water treatment with a 75 krad ..gamma..-irradiation, (6) 75 krad ..gamma..-irradiation only, and (7) hot water treatment with a 100 krad ..gamma..-irradiation. The items of observation were: surface yellowing, surface decaying, quality of texture, and length of period lasted after irradiation for 50% marketable papayas. The results of this study showed that a shelf-life extension of six days could be obtained for papayas subjected to hot water (50 to 55/sup 0/C) treatment and a 100 krad irradiation. 3 refs., 2 figs., 2 tabs.

  1. Chemotrophic Ecosystem Beneath the Larsen Ice Shelf, Antarctica

    Science.gov (United States)

    Leventer, A.; Domack, E.; Ishman, S.; Sylva, S.; Willmott, V.; Huber, B.; Padman, L.

    2005-12-01

    The first living chemotrophic ecosystem in the Southern Ocean was discovered in a region of the seafloor previously occupied by the Larsen-B Ice Shelf. A towed video survey documents an ecosystem characterized by a bottom-draping white mat that appears similar to mats of Begiattoa, hydrogen sulfide oxidizing bacteria, and bivalves, 20-30 cm large, similar to vesicomyid clams commonly found at cold seeps. The carbon source is unknown; three potential sources are hypothesized. First, thermogenically-produced methane may occur as the marine shales of this region are similar to hydrocarbon-bearing rocks to the north in Patagonia. The site occurs in an 850 m deep glacially eroded trough located along the contact between Mesozoic-Tertiary crystalline basement and Cretaceous-Tertiary marine rocks; decreased overburden could have induced upward fluid flow. Also possible is the dissociation of methane hydrates, a process that might have occurred as a result of warming oceanic bottom waters. This possibility will be discussed in light of the distribution of early diagenetic ikaite in the region. Third, the possibility of a biogenic methane source will be discussed. A microstratigraphic model for the features observed at the vent sites will be presented; the system is comprised of mud mounds with central vents and surrounding mud flow channels. A series of still image mosaics record the dynamic behavior of the system, which appears to demonstrate episodic venting. These images show the spatial relationship between more and less active sites, as reflected in the superposition of several episodes of mud flow activity and the formation of mud channels. In addition, detailed microscale features of the bathymetry of the site will be presented, placing the community within the context of glacial geomorphologic features. The Larsen-B Ice Shelf persisted through the entire Holocene, limiting carbon influx from a photosynthetic source. Tidal modeling of both pre and post breakup

  2. An Altimetry-Derived Index of the Offshore Forcing on the "Pressure Point" of the West Florida Shelf: Anomalous Upwelling and Its Influence on Harmful Algal Blooms

    Science.gov (United States)

    Liu, Y.; Weisberg, R. H.; Lenes, J. M.; Zheng, L.; Hubbard, K.; Walsh, J. J.

    2017-12-01

    Gulf of Mexico Loop Current (LC) interactions with the West Florida Shelf (WFS) slope play an important role in shelf ecology through the upwelling of new inorganic nutrients across the shelf break. This is particularly the case when the LC impinges upon the shelf slope in the southwest portion of the WFS near the Dry Tortugas. By contacting shallow water isobaths at this "pressure point" the LC forcing sets the entire shelf into motion. Characteristic patterns of LC interactions with the WFS and their occurrences are identified from altimetry data using unsupervised neural network, self-organizing map. The duration of the occurrences of such LC patterns is used as an indicator of offshore forcing of anomalous upwelling. Consistency is found between the altimetry-derived offshore forcing and the occurrence and severity of WFS coastal blooms of the toxic dinoflagellate, Karenia brevis: years without major blooms tend to have prolonged LC contact at the "pressure point," whereas years with major blooms tend not to have prolonged offshore forcing. Resetting the nutrient state of the shelf by the coastal ocean circulation in response to deep-ocean forcing demonstrates the importance of physical oceanography in shelf ecology. A satellite altimetry-derived seasonal predictor for major K. brevis blooms is also proposed.

  3. Cascading failure in the wireless sensor scale-free networks

    Science.gov (United States)

    Liu, Hao-Ran; Dong, Ming-Ru; Yin, Rong-Rong; Han, Li

    2015-05-01

    In the practical wireless sensor networks (WSNs), the cascading failure caused by a failure node has serious impact on the network performance. In this paper, we deeply research the cascading failure of scale-free topology in WSNs. Firstly, a cascading failure model for scale-free topology in WSNs is studied. Through analyzing the influence of the node load on cascading failure, the critical load triggering large-scale cascading failure is obtained. Then based on the critical load, a control method for cascading failure is presented. In addition, the simulation experiments are performed to validate the effectiveness of the control method. The results show that the control method can effectively prevent cascading failure. Project supported by the Natural Science Foundation of Hebei Province, China (Grant No. F2014203239), the Autonomous Research Fund of Young Teacher in Yanshan University (Grant No. 14LGB017) and Yanshan University Doctoral Foundation, China (Grant No. B867).

  4. Layered mixing on the New England Shelf in summer

    Science.gov (United States)

    Wang, Jianing; Greenan, Blair J. W.; Lu, Youyu; Oakey, Neil S.; Shaw, William J.

    2014-09-01

    The layered structure of stratification and mixing on the New England Shelf (NES) in summer is examined by analyzing a comprehensive set of observations of hydrography, currents and turbulence. A clear distinction in mixing characteristics between the midcolumn water (consisting of subsurface stratification, middepth weak stratification and lower-layer stratification) and a well-mixed bottom boundary layer (BBL) is revealed. The combination of subtidal Ekman onshore bottom transport and cross-shore density gradient created a lower-layer stratification that inhibited the upward extension of the BBL turbulence. The BBL mixing was related to strong shear generated by bottom stress, and the magnitude and periodic variation of BBL mixing was determined by both the tidal and subtidal flows. Mixing in the midcolumn water occurred under stably stratified conditions and showed correspondence with the occurrence of near-inertial and semidiurnal internal waves. Positive correlations between buoyancy frequency squared (N2) and shear variance (S2), S2 and dissipation rate (ɛ), N2 and ɛ are established in the midcolumn, but not in the BBL. The midcolumn ɛ was reasonably described by a slightly modified MacKinnon-Gregg (MG) model.

  5. Invariant mass distributions in cascade decays

    CERN Document Server

    Miller, D J; Raklev, A R

    2006-01-01

    We derive analytical expressions for the shape of the invariant mass distributions of massless Standard Model endproducts in cascade decays involving massive New Physics (NP) particles, D -> Cc -> Bbc -> Aabc, where the final NP particle A in the cascade is unobserved and where two of the particles a, b, c may be indistinguishable. Knowledge of these expressions can improve the determination of NP parameters at the LHC. The shape formulas are composite, but contain nothing more complicated than logarithms of simple expressions. We study the effects of cuts, final state radiation and detector effects on the distributions through Monte Carlo simulations, using a supersymmetric model as an example. We also consider how one can deal with the width of NP particles and with combinatorics from the misidentification of final state particles. The possible mismeasurements of NP masses through `feet' in the distributions are discussed. Finally, we demonstrate how the effects of different spin configurations can be inclu...

  6. Invariant mass distributions in cascade decays

    International Nuclear Information System (INIS)

    Miller, David J.; Osland, Per; Raklev, Are R.

    2006-01-01

    We derive analytical expressions for the shape of the invariant mass distributions of massless Standard Model endproducts in cascade decays involving massive New Physics (NP) particles, D→Cc→Bbc→Aabc, where the final NP particle A in the cascade is unobserved and where two of the particles a, b, c may be indistinguishable. Knowledge of these expressions can improve the determination of NP parameters at the LHC. The shape formulas are composite, but contain nothing more complicated than logarithms of simple expressions. We study the effects of cuts, final state radiation and detector effects on the distributions through Monte Carlo simulations, using a supersymmetric model as an example. We also consider how one can deal with the width of NP particles and with combinatorics from the misidentification of final state particles. The possible mismeasurements of NP masses through 'feet' in the distributions are discussed. Finally, we demonstrate how the effects of different spin configurations can be included in the distributions

  7. Cascade-based attacks on complex networks

    Science.gov (United States)

    Motter, Adilson E.; Lai, Ying-Cheng

    2002-12-01

    We live in a modern world supported by large, complex networks. Examples range from financial markets to communication and transportation systems. In many realistic situations the flow of physical quantities in the network, as characterized by the loads on nodes, is important. We show that for such networks where loads can redistribute among the nodes, intentional attacks can lead to a cascade of overload failures, which can in turn cause the entire or a substantial part of the network to collapse. This is relevant for real-world networks that possess a highly heterogeneous distribution of loads, such as the Internet and power grids. We demonstrate that the heterogeneity of these networks makes them particularly vulnerable to attacks in that a large-scale cascade may be triggered by disabling a single key node. This brings obvious concerns on the security of such systems.

  8. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mattheis, L. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kunkle, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Howard, L. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lubliner, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  9. DECISION SUPPORT TOOL FOR RETAIL SHELF SPACE OPTIMIZATION

    OpenAIRE

    B. RAMASESHAN; N. R. ACHUTHAN; R. COLLINSON

    2008-01-01

    Efficient allocation of shelf space and product assortment can significantly improve a retailer's profitability. This paper addresses the problem from the perspective of an independent franchise retailer. A Category Management Decision Support Tool (CMDST) is proposed that efficiently generates optimal shelf space allocations and product assortments by using the existing scarce resources, resulting in increased profitability. CMDST utilizes two practical integrated category management models ...

  10. Environmental controls on micro fracture processes in shelf ice

    Science.gov (United States)

    Sammonds, Peter

    2013-04-01

    The recent retreat and collapse of the ice shelves on the Antarctic Peninsula has been associated with regional atmospheric warming, oceanic warming, increased summer melt and shelf flexure. Although the cause of collapse is a matter of active discussion, the process is that of fracture of a creep-brittle material, close to its melting point. The environmental controls on how fracturing initiates, at a micro-scale, strongly determine the macroscopic disintegration of ice shelves. In particular the shelf temperature profile controls the plasticity of the ice shelf; the densification of shelf ice due to melting and re-freezing affects the crack tip stress intensity; the accretion of marine ice at the bottom of the shelf imposes a thermal/mechanical discontinuity; saline environments control crack tip stress corrosion; cyclic loading promotes sub-critical crack propagation. These strong environmental controls on shelf ice fracture means that assessing shelf stability is a non-deterministic problem. How these factors may be parameterized in ice shelf models, through the use of fracture mechanisms maps, is discussed. The findings are discussed in relation to the stability of Larsen C.

  11. The Statoil/Hydro fusion in a continental shelf perspective

    International Nuclear Information System (INIS)

    Osmundsen, Petter

    2007-01-01

    The article analysis the consequences of the Statoil/Hydro merger on the development on the Norwegian continental shelf. Various indicators of results of the market power the merger are presented and the effects of reduced competition on the markets are discussed. The advantages of the merger on the activities on the shelf are analyzed. (tk)

  12. Damage reduces shelf-life of sweetpotato during marketing | Mtunda ...

    African Journals Online (AJOL)

    Damage reduces shelf-life of sweetpotato during marketing. ... K. Mtunda, D. Chilosa, E. Rwiza, M. Kilima, H. Kiozya, R. Munisi, R. Kapinga, D. Rees. Abstract. Although sweetpotato is primarily grown for home consumption, marketing is becoming increasingly important, and in this case, short shelf-life of the roots is a major ...

  13. State of the soft bottoms of the continental shelf

    International Nuclear Information System (INIS)

    Guzman Alvis, Angela I; Solano, Oscar David

    2002-01-01

    The presented information, it is based on studies carried out on the continental shelf of the Colombian Caribbean, mainly in the Gulf of Morrosquillo and the Magdalena and Guajira departments in the last ten years. A diagnostic is done of the soft bottoms of the Colombian continental shelf

  14. Geochemistry of sediments of the eastern continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.; Paropkari, A.L.; Murty, P.S.N.

    The bulk and partition geochemistry of Al, Fe, Ti, Mn, Zn, and Cu have been investigated in sediments of the eastern continental shelf of India. The results show that (1) the bulk geochemistry varies from one shelf unit to the other, (2) all...

  15. Shelf-life dating of shelf-stable strawberry juice based on survival analysis of consumer acceptance information.

    Science.gov (United States)

    Buvé, Carolien; Van Bedts, Tine; Haenen, Annelien; Kebede, Biniam; Braekers, Roel; Hendrickx, Marc; Van Loey, Ann; Grauwet, Tara

    2018-07-01

    Accurate shelf-life dating of food products is crucial for consumers and industries. Therefore, in this study we applied a science-based approach for shelf-life assessment, including accelerated shelf-life testing (ASLT), acceptability testing and the screening of analytical attributes for fast shelf-life predictions. Shelf-stable strawberry juice was selected as a case study. Ambient storage (20 °C) had no effect on the aroma-based acceptance of strawberry juice. The colour-based acceptability decreased during storage under ambient and accelerated (28-42 °C) conditions. The application of survival analysis showed that the colour-based shelf-life was reached in the early stages of storage (≤11 weeks) and that the shelf-life was shortened at higher temperatures. None of the selected attributes (a * and ΔE * value, anthocyanin and ascorbic acid content) is an ideal analytical marker for shelf-life predictions in the investigated temperature range (20-42 °C). Nevertheless, an overall analytical cut-off value over the whole temperature range can be selected. Colour changes of strawberry juice during storage are shelf-life limiting. Combining ASLT with acceptability testing allowed to gain faster insight into the change in colour-based acceptability and to perform shelf-life predictions relying on scientific data. An analytical marker is a convenient tool for shelf-life predictions in the context of ASLT. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  16. Fluorescent dissolved organic matter in the continental shelf waters ...

    Indian Academy of Sciences (India)

    Ocean and receives a large freshwater influx ca. 1600 km3 yr ... oceanic surface area of 1.13%, this influx consti- ... the Bay. The export flux of total organic carbon ..... Cycles 20. GB2006. Benner R 2002 Chemical composition and reactivity;.

  17. Dynamic behavior and control of product enrichment in a centrifuge cascade

    International Nuclear Information System (INIS)

    Okamoto, Tsuyoshi; Suzuki, Atsuyuki; Nishimura, Hideo.

    1989-05-01

    It was agreed as a conclusion of the HEXAPARTITE project that a limited frequency unannounced access (LFUA) inspection should be carried out in a centrifuge type enrichment plant as a basic safeguards approach. It might be adopted at a large scale, future commercial enrichment plant, too. Application of the LFUA approach to such a plant, however, should be fully investigated because the plant will have not only a larger capability of enriching uranium 235 but also a more sensitive information to be protected from the commercial and non-proliferation viewpoint. As a part of a design study on the safeguards approach for a model commercial plant, a study of process simulation of the plant has been carried out. This report describes a result of the study. When a commercial uranium enrichment plant is constructed, a nuisance problem arises; What kind of products should be produced from the plant in order to match a wide range of nuclear fuel enrichment requirements for light-water power reactors. In this report, a reasonable solution to such a problem is investigated. At first, a transient analysis of start-up for a model centrifuge cascade is made by using the dynamic equations, which were so developed as to be able to accurately compute interstage flow rates and enrichment in a transient state. Then it is investigated how wide in its acceptable range the product enrichment can be controlled by regulating cascade<