Evidence of zooplankton vertical migration from continuous Southern Adriatic buoy current-meter records (E2-M3A)

NASA Astrophysics Data System (ADS)

Ursella, Laura; Cardin, Vanessa; Batistić, Mirna

2017-04-01

The E2-M3A Station is deployed in the southern Adriatic Sea, at about 1200 m depth, in the center of the cyclonic gyre where deep convection process takes place, involving both the atmosphere and the ocean dynamics and forming new dense and oxygenated waters, thus triggering the solubility and the biological pump. In particular, the E2M3A is equipped with an upward looking 150 kHz RDI-Acoustic Doppler Current Profiler (ADCP) positioned between 265 and 320 m depth, with a vertical resolution of 5 m and a range of 250-300 m. The mooring line has been in water since November 2006, with an interruption from September 2010 until May 2011. ADCP backscattering signal is very useful in determining zooplankton distribution and variability at various time scales, including seasonal/annual behavior and diel vertical migration (DVM). From ADCP backscattering signal, backscattering strength (Sv) was calculated for the entire dataset. Sv permits to quantify qualitatively the scatters present in the water, i.e. the particulate and/or the phyto/zoo-plankton. Zooplankton distribution is dependent on phytoplankton presence and blooms, which on its own depend on nutrients availability (related to wind-induced vertical mixing), but also on sunlight. The variation in time of Sv together with vertical velocity allows for measuring DVM of zooplankton and its variability with seasons and years. Alternation of high and low values for Sv are present all year long with differences in intensities in particular in the surface layer. Quite high values for Sv are found in spring and summer; in spring they are found along a large part of the water column, while in summer they are detected prevalently in the upper part of the measurement range. This behavior is related to the conditions of the water column, i.e. mixing and nutrients availability, which influence phytoplankton blooms and therefore zooplankton growing and movements. Correlating Net Primary Production obtained from model and Mixed Layer Depth, a delay of two months in the bloom of phytoplankton with respect to deepest mixing is found. Power Spectra of Sv show a major peak at 24 h that corresponds to the classical nocturnal-diurnal migration, and a secondary important peak at the period of 12 hours that indicates a different type of DVM pattern, the twilight migration. The ultimate factor behind DVM seems to be the minimization of the risk of predation from fishes and other carnivorous groups. Calculating the monthly mean daily cycle of the Sv, it is evident that there is a decrease in Sv at sunrise, while it increases at sunset. The highest values in the derivative of Sv, as well as highest values in the vertical velocity (w), coincide in time with sunset and sunrise. In particular, w is negative (downward movement) at sunrise while it is positive (upward movement) at sunset, and in some cases absolute value of w (|w|) reaches 5 cm/s. The hour of occurrence of |w| greater than 4.5 cm/s follows the curves in time of the hours of sunset and sunrise, which are changing throughout the year.

Larval biology of the crab Rhithropanopeus harrisii (Gould): a synthesis.

PubMed

Forward, Richard B

2009-06-01

This synthesis reviews the physiological ecology and behavior of larvae of the benthic crab Rhithropanopeus harrisii, which occurs in low-salinity areas of estuaries. Larvae are released rhythmically around the time of high tide in tidal estuaries and in the 2-h interval after sunset in nontidal estuaries. As in most subtidal crustaceans, the timing of larval release is controlled by the developing embryos, which release peptide pheromones that stimulate larval release behavior by the female to synchronize the time of egg hatching. Larvae pass through four zoeal stages and a postlarval or megalopal stage that are planktonic before metamorphosis. They are retained near the adult population by means of an endogenous tidal rhythm in vertical migration. Larvae have several safeguards against predation: they undergo nocturnal diel vertical migration (DVM) and have a shadow response to avoid encountering predators, and they bear long spines as a deterrent. Photoresponses during DVM and the shadow response are enhanced by exposure to chemical cues from the mucus of predator fishes and ctenophores. The primary visual pigment has a spectral sensitivity maximum at about 500 nm, which is typical for zooplankton and matches the ambient spectrum at twilight. Larvae can detect vertical gradients in temperature, salinity, and hydrostatic pressure, which are used for depth regulation and avoidance of adverse environmental conditions. Characteristics that are related to the larval habitat and are common to other crab larval species are considered.

The diel vertical migration patterns and individual swimming behavior of overwintering sprat Sprattus sprattus

NASA Astrophysics Data System (ADS)

Solberg, Ingrid; Kaartvedt, Stein

2017-02-01

We addressed the behavioral patterns and DVM dynamics of sprat overwintering in a Norwegian fjord (150 m) with increasing hypoxia by depth. An upward-facing echosounder deployed at the bottom and cabled to shore provided 4 months of continuous acoustic data. This enabled detailed studies of individual behavior, specifically allowing assessment of individual vertical migrations at dusk and dawn in relation to light, analysis of so-called rise-and-sink swimming, and investigation of the sprat' swimming activity and behavior in severely hypoxic waters. Field campaigns supplemented the acoustic studies. The acoustic records showed that the main habitat for sprat was the upper ∼65 m where oxygen concentrations were ⩾0.7 mL O2 L-1. The sprat schooled at ∼50 m during daytime and initiated an upward migration about 1 h prior to sunset. While some sprat migrated to surface waters, other individuals interrupted the ascent when at ∼20-30 m, and returned to deeper waters ∼20-50 min after sunset. Sprat at depth was on average larger, yet individuals made excursions to- and from upper layers. Sprat were swimming in a "rise and sink" pattern at depth, likely related to negative buoyancy. Short-term dives into waters with less than 0.45 mL O2 L-1 were interpreted as feeding forays for abundant overwintering Calanus spp. The deep group of sprat initiated a dawn ascent less than 1 h before sunrise, ending at 20-30 m where they formed schools. They subsequently returned to deeper waters about ∼20 min prior to sunrise. Measurements of surface light intensities indicated that the sprat experienced lower light levels in upper waters at dawn than at dusk. The vertical swimming speed varied significantly between the behavioral tasks. The mixed DVM patterns and dynamic nocturnal behavior of sprat persisted throughout winter, likely shaped by individual strategies involving optimized feeding and predator avoidance, as well as relating to temperature, hypoxia and negative buoyancy.

Bio-mixing due to Diel Vertical Migration of Daphnia spp. in a Small Lake

NASA Astrophysics Data System (ADS)

Simoncelli, Stefano; Wain, Danielle; Thackeray, Stephen

2016-04-01

Bio-turbulence or bio-mixing refers to the contribution of living organisms towards the mixing of waters in oceans and lakes. Experimental measurements in an unstratified tank by Wilhelmus & Dabiri (2014) show that zooplankton can trigger fluid instabilities through collective motions and that energy is imparted to scales bigger than organism's size of few mm. Length scales analysis, for low-Reynolds-number organisms in stratified water by Leshansky & Pismen (2010) and Kunze (2011), estimate eddy diffusivity up two orders of magnitude larger than the molecular thermal diffusivity. Very recently, Wand & Ardekani (2015) showed a maximum diffusivity of 10-5 m2/s for millimetre-sized organisms from numerical simulations in the intermediate Reynolds number regime. Here we focus our attention on turbulence generated by the vertical migration of zooplankton in a small lake, mostly populated by Daphnia spp. This very common species, belonging to Cladocera order, is engaged in a vertical migration (DVM) at sunset, with many organisms crossing the thermocline despite the density stratification. During the ascension they may create hydrodynamic disturbances in the lake interior where the stratification usually suppresses the vertical diffusion. We have conducted five turbulence experiments in Vobster Quay, a small (area ˜ 59,000 m2), deep (40m) man-made basin with small wind fetch and steep sides, located in the South West UK. Turbulence was measured with a temperature microstructure profiler. To asses the zooplankton vertical concentration we used a 100 μm mesh net, by collecting and analyzing samples in 8 layers of the lake. A bottom-mounted acoustic Doppler current profiler was also employed to track their concentration and migration with the measured backscatter strength. Measured dissipation rates ɛ during the day showed low turbulence level (<= 10-8 W/Kg) in the thermocline and in the zooplankton layer. Turbulence, during the DVM in two different days, is highest on the surface, likely due to surface processes. Peaks of 10-6.5 W/kg were measured within the migrating zooplankton layer with respect to profiles before sunset and estimated eddy diffusivity was as much as 10-5 m2/s. Before and after the time series there was no wind and penetrative convection associated with night-time cooling wasn't active during the experiments. Given the uncertainty in measuring the length scales of turbulence associated with small zooplankton and the presence of turbulence patches outside the migrating layer, further datasets are needed for definitive conclusions.

Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter.

PubMed

Last, Kim S; Hobbs, Laura; Berge, Jørgen; Brierley, Andrew S; Cottier, Finlo

2016-01-25

In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological migration have historically been considered non-existent [1]. However, diel vertical migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as yet, unexplained. Here, we present evidence of an unexpected uniform behavior across the entire Arctic, in fjord, shelf, slope and open sea, where vertical migrations of zooplankton are driven by lunar illumination. A shift from solar-day (24-hr period) to lunar-day (24.8-hr period) vertical migration takes place in winter when the moon rises above the horizon. Further, mass sinking of zooplankton from the surface waters and accumulation at a depth of ∼50 m occurs every 29.5 days in winter, coincident with the periods of full moon. Moonlight may enable predation of zooplankton by carnivorous zooplankters, fish, and birds now known to feed during the polar night [4]. Although primary production is almost nil at this time, lunar vertical migration (LVM) may facilitate monthly pulses of carbon remineralization, as they occur continuously in illuminated mesopelagic systems [5], due to community respiration of carnivorous and detritivorous zooplankton. The extent of LVM during the winter suggests that the behavior is highly conserved and adaptive and therefore needs to be considered as "baseline" zooplankton activity in a changing Arctic ocean [6-9]. VIDEO ABSTRACT. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Deep-pelagic (0-3000 m) fish assemblage structure over the Mid-Atlantic Ridge in the area of the Charlie-Gibbs Fracture Zone

NASA Astrophysics Data System (ADS)

Cook, April B.; Sutton, Tracey T.; Galbraith, John K.; Vecchione, Michael

2013-12-01

Only a miniscule fraction of the world’s largest volume of living space, the ocean’s midwater biome, has ever been sampled. As part of the International Census of Marine Life field project on Mid-Atlantic Ridge ecosystems (MAR-ECO), a discrete-depth trawling survey was conducted in 2009 aboard the NOAA FSV Henry B. Bigelow to examine the pelagic faunal assemblage structure and distribution over the Charlie-Gibbs Fracture Zone (CGFZ) of the northern Mid-Atlantic Ridge. Day/night sampling at closely spaced stations allowed the first characterization of diel vertical migration of pelagic nekton over the MAR-ECO study area. Discrete-depth sampling from 0-3000 m was conducted using a Norwegian “Krill” trawl with five codends that were opened and closed via a pre-programmed timer. Seventy-five species of fish were collected, with a maximum diversity and biomass observed between depths of 700-1900 m. A gradient in sea-surface temperature and underlying watermasses, from northwest to southeast, was mirrored by a similar gradient in ichthyofaunal diversity. Using multivariate analyses, eight deep-pelagic fish assemblages were identified, with depth as the primary discriminatory variable. Strong diel vertical migration (DVM) of the mesopelagic fauna was a prevalent feature of the study area, though the numerically dominant fish, Cyclothone microdon (Gonostomatidae), exhibited a broad (0-3000 m) vertical distribution and did not appear to migrate on a diel basis. Three patterns of vertical distribution were observed in the study area: (a) DVM of mesopelagic, and possibly bathypelagic, taxa; (b) broad vertical distribution spanning meso- and bathypelagic depths; and (c) discrete vertical distribution within a limited depth range. Overall species composition and rank order of abundance of fish species agreed with two previous expeditions to the CGFZ (1982-1983 and 2004), suggesting some long-term consistency in the ichthyofaunal composition of the study area, at least in the summer. Frequent captures of putative bathypelagic fishes, shrimps, and cephalopods in the epipelagic zone (0-200 m) were confirmed. The results of this expedition reveal distributional patterns unlike those previously reported for open-ocean ecosystems, with the implication of increased transfer efficiency of surface production to great depths in the mid-North Atlantic.

Diel variations of the bathymetric distribution of zooplankton groups and biomass in Cap-Ferret Canyon, France

NASA Astrophysics Data System (ADS)

Maycas, Encarna Ribera; Bourdillon, André; Macquart-Moulin, Claude; Passelaigue, Françoise; Patriti, Gilbert

1999-10-01

The bathymetric distribution, abundance and diel vertical migrations (DVM) of zooplankton were investigated along the axis of the Cap-Ferret Canyon (Bay of Biscay, French Atlantic coast) by a consecutive series of synchronous net hauls that sampled the whole water column (0-2000 m in depth) during a diel cycle. The distribution of appendicularians (maximum 189 individuals m -3), cladocerans (maximum 287 individuals m -3), copepods (copepods<4 mm, maximum 773 individuals m -3, copepods>4 mm, maximum 13 individuals m -3), ostracods (maximum 8 individuals m -3), siphonophores (maximum >2 individuals m -3) and peracarids (maximum >600 individuals 1000 m -3) were analysed and represented by isoline diagrams. The biomass of total zooplankton (maximum 18419 μg C m -3, 3780 μg N m -3) and large copepods (>4 mm maximum 2256 μg C m -3, 425 μg N m -3) also were determined. Vertical migration was absent or affected only the epipelagic zone for appendicularians, cladocerans, small copepods and siphonophores. Average amplitude of vertical migration was about 400-500 m for ostracods, some hyperiids and mysids, and large copepods, which were often present in the epipelagic, mesopelagic, and bathypelagic zones. Large copepods can constitute more than 80% of the biomass corresponding to total zooplankton. They may play an important role in the active vertical transfer of carbon and nitrogen.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, R.; Hauss, H.; Buchholz, F.; Melzner, F.

2015-10-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs.

Pulsed remineralisation in the northwestern Mediterranean Sea: a hypothesis

NASA Astrophysics Data System (ADS)

Denis, Michel; Martin, Valérie; Momzikoff, André; Gondry, Geneviève; Stemmann, Lars; Demers, Serge; Gorsky, Gaby; Andersen, Valérie

2003-02-01

A general study of biogeochemical processes (DYNAPROC cruise) was conducted in May 1995 at a time-series station in the open northwestern Mediterranean Sea where horizontal advection was weak. Short-term variations of the vertical distributions of pico- and nanophytoplankton were investigated over four 36-h cycles, along with parallel determinations of metabolic CO 2 production rates and amino acid-containing colloid (AACC) concentrations at the chlorophyll maximum depth. The vertical (0-1000-m depth) distributions of (i) AACC, (ii) suspended particles and (iii) metabolic CO 2 production rate were documented during the initial and final stages of these 36-h cycles. This study was concerned with diel vertical migration (DVM) of zooplankton, which provided periodic perturbations. Accordingly, the time scale of the experimental work varied from a few hours to a few days. Although all distributions exhibited a periodic behaviour, AACC distributions were generally not linked to diel vertical migrations. In the subsurface layer, Synechococcus made the most abundant population and large variations in concentration were observed both at day and at night. The corresponding integrated (over the upper 90 m) losses of Synechococcus during one night pointed to a potential source of exported organic matter amounting to 534 mg C m -2. This study stresses the potential importance of organic matter export from the euphotic zone through the daily grazing activity of vertically migrating organisms, which would not be accounted for by measurements at longer time scales. The metabolic CO 2 production exhibited a peak of activity below 500 m that was shifted downward, apparently in a recurrent way and independently of the vertical distributions of AACC or of suspended particulate material. To account for this phenomenon, a «sustained wave train» hypothesis is proposed that combines the effect of the diel superficial faecal pellet production by swarming migrators and the repackaging activity of the nonmigrating midwater populations. Our results confirm the recent finding that the particulate compartment is not the major source of the observed instantaneous remineralisation rate and shed a new light on the fate of organic matter in the aphotic zone.

At-sea behavior varies with lunar phase in a nocturnal pelagic seabird, the swallow-tailed gull

USGS Publications Warehouse

Cruz, Sebastian M.; Hooten, Mevin; Huyvaert, Kathryn P.; Proaño, Carolina B.; Anderson, David J.; Afanasyev, Vsevolod; Wikelski, Martin

2013-01-01

Strong and predictable environmental variability can reward flexible behaviors among animals. We used long-term records of activity data that cover several lunar cycles to investigate whether behavior at-sea of swallow-tailed gulls Creagrus furcatus, a nocturnal pelagic seabird, varied with lunar phase in the Galápagos Islands. A Bayesian hierarchical model showed that nighttime at-sea activity of 37 breeding swallow-tailed gulls was clearly associated with changes in moon phase. Proportion of nighttime spent on water was highest during darker periods of the lunar cycle, coinciding with the cycle of the diel vertical migration (DVM) that brings prey to the sea surface at night. Our data show that at-sea behavior of a tropical seabird can vary with environmental changes, including lunar phase.

At-sea behavior varies with lunar phase in a nocturnal pelagic seabird, the swallow-tailed gull.

PubMed

Cruz, Sebastian M; Hooten, Mevin; Huyvaert, Kathryn P; Proaño, Carolina B; Anderson, David J; Afanasyev, Vsevolod; Wikelski, Martin

2013-01-01

Strong and predictable environmental variability can reward flexible behaviors among animals. We used long-term records of activity data that cover several lunar cycles to investigate whether behavior at-sea of swallow-tailed gulls Creagrus furcatus, a nocturnal pelagic seabird, varied with lunar phase in the Galápagos Islands. A Bayesian hierarchical model showed that nighttime at-sea activity of 37 breeding swallow-tailed gulls was clearly associated with changes in moon phase. Proportion of nighttime spent on water was highest during darker periods of the lunar cycle, coinciding with the cycle of the diel vertical migration (DVM) that brings prey to the sea surface at night. Our data show that at-sea behavior of a tropical seabird can vary with environmental changes, including lunar phase.

Migrant biomass and respiratory carbon flux by zooplankton and micronekton in the subtropical northeast Atlantic Ocean (Canary Islands)

NASA Astrophysics Data System (ADS)

Ariza, A.; Garijo, J. C.; Landeira, J. M.; Bordes, F.; Hernández-León, S.

2015-05-01

Diel Vertical Migration (DVM) in marine ecosystems is performed by zooplankton and micronekton, promoting a poorly accounted export of carbon to the deep ocean. Major efforts have been made to estimate carbon export due to gravitational flux and to a lesser extent, to migrant zooplankton. However, migratory flux by micronekton has been largely neglected in this context, due to its time-consuming and difficult sampling. In this paper, we evaluated gravitational and migratory flux due to the respiration of zooplankton and micronekton in the northeast subtropical Atlantic Ocean (Canary Islands). Migratory flux was addressed by calculating the biomass of migrating components and measuring the electron transfer system (ETS) activity in zooplankton and dominant species representing micronekton (Euphausia gibboides, Sergia splendens and Lobianchia dofleini). Our results showed similar biomass in both components. The main taxa contributing to DVM within zooplankton were juvenile euphausiids, whereas micronekton were mainly dominated by fish, followed by adult euphausiids and decapods. The contribution to respiratory flux of zooplankton (3.4 ± 1.9 mg C m-2 d-1) was similar to that of micronekton (2.9 ± 1.0 mg C m-2 d-1). In summary, respiratory flux accounted for 53% (range 23-71) of the gravitational flux measured at 150 m depth (11.9 ± 5.8 mg C m-2 d-1). However, based on larger migratory ranges and gut clearance rates, micronekton are expected to be the dominant component that contributes to carbon export in deeper waters. Micronekton estimates in this paper as well as those in existing literature, although variable due to regional differences and difficulties in calculating their biomass, suggest that carbon fluxes driven by this community are important for future models of the biological carbon pump.

Spatial Dynamics and Expanded Vertical Niche of Blue Sharks in Oceanographic Fronts Reveal Habitat Targets for Conservation

PubMed Central

Queiroz, Nuno; Humphries, Nicolas E.; Noble, Leslie R.; Santos, António M.; Sims, David W.

2012-01-01

Dramatic population declines among species of pelagic shark as a result of overfishing have been reported, with some species now at a fraction of their historical biomass. Advanced telemetry techniques enable tracking of spatial dynamics and behaviour, providing fundamental information on habitat preferences of threatened species to aid conservation. We tracked movements of the highest pelagic fisheries by-catch species, the blue shark Prionace glauca, in the North-east Atlantic using pop-off satellite-linked archival tags to determine the degree of space use linked to habitat and to examine vertical niche. Overall, blue sharks moved south-west of tagging sites (English Channel; southern Portugal), exhibiting pronounced site fidelity correlated with localized productive frontal areas, with estimated space-use patterns being significantly different from that of random walks. Tracked female sharks displayed behavioural variability in diel depth preferences, both within and between individuals. Diel depth use ranged from normal DVM (nDVM; dawn descent, dusk ascent), to reverse DVM (rDVM; dawn ascent, dusk descent), to behavioural patterns where no diel differences were apparent. Results showed that blue sharks occupy some of the most productive marine zones for extended periods and structure diel activity patterns across multiple spatio-temporal scales in response to particular habitat types. In so doing, sharks occupied an extraordinarily broad vertical depth range for their size (1.0–2.0 m fork length), from the surface into the bathypelagic realm (max. dive depth, 1160 m). The space-use patterns of blue sharks indicated they spend much of the time in areas where pelagic longlining activities are often highest, and in depth zones where these fisheries particularly target other species, which could account for the rapid declines recently reported for blue sharks in many parts of the world's oceans. Our results provide habitat targets for blue shark conservation that may also be relevant to other pelagic species. PMID:22393403

At–Sea Behavior Varies with Lunar Phase in a Nocturnal Pelagic Seabird, the Swallow-Tailed Gull

PubMed Central

Cruz, Sebastian M.; Hooten, Mevin; Huyvaert, Kathryn P.; Proaño, Carolina B.; Anderson, David J.; Afanasyev, Vsevolod; Wikelski, Martin

2013-01-01

Strong and predictable environmental variability can reward flexible behaviors among animals. We used long-term records of activity data that cover several lunar cycles to investigate whether behavior at-sea of swallow-tailed gulls Creagrus furcatus, a nocturnal pelagic seabird, varied with lunar phase in the Galápagos Islands. A Bayesian hierarchical model showed that nighttime at-sea activity of 37 breeding swallow-tailed gulls was clearly associated with changes in moon phase. Proportion of nighttime spent on water was highest during darker periods of the lunar cycle, coinciding with the cycle of the diel vertical migration (DVM) that brings prey to the sea surface at night. Our data show that at-sea behavior of a tropical seabird can vary with environmental changes, including lunar phase. PMID:23468889

Distributions of larval and juvenile/adult stages of the Antarctic myctophid fish, Electrona antarctica, off Wilkes Land in East Antarctica

NASA Astrophysics Data System (ADS)

Moteki, Masato; Fujii, Kentaro; Amakasu, Kazuo; Shimada, Keishi; Tanimura, Atsushi; Odate, Tsuneo

2017-06-01

Myctophid fish are an important component of the Southern Ocean food web because of their very high biomass. This study investigated the spatial distributions of larval and juvenile/adult stages of the Antarctic myctophid Electrona antarctica. Fish were sampled in January 2011 and 2012 on a transect along 140°E and in January 2013 along 110°E using two different opening/closing net systems. In total, 1075 specimens of E. antarctica were collected: 948 larvae, 127 juveniles/adults, and 2 in the transformation stage. Most larvae were collected at 5-200 m depth, with diel vertical migration (DVM) not apparent. Larvae were mainly distributed in the Modified Circumpolar Deep Water (-1.5 °C-2.0 °C). By contrast, an analysis of the echogram at 38 kHz and discrete depth samples implied that juveniles/adults undertook DVM except in the continental slope area (65.5°S). As the distribution of krill is limited to the cold water mass (<-1.5 °C) along the continental slope, E. antarctica and krill populations are spatially separated off Wilkes Land during summer. According to the previously estimated larval period of 30-47 days, E. antarctica may spawn in late November to December in the marginal ice zone or near the sea ice edge. This study suggests that the environment related to sea ice provides a nursery ground for early stage larvae of E. antarctica.

Vertical distribution, composition and migratory patterns of acoustic scattering layers in the Canary Islands

NASA Astrophysics Data System (ADS)

Ariza, A.; Landeira, J. M.; Escánez, A.; Wienerroither, R.; Aguilar de Soto, N.; Røstad, A.; Kaartvedt, S.; Hernández-León, S.

2016-05-01

Diel vertical migration (DVM) facilitates biogeochemical exchanges between shallow waters and the deep ocean. An effective way of monitoring the migrant biota is by acoustic observations although the interpretation of the scattering layers poses challenges. Here we combine results from acoustic observations at 18 and 38 kHz with limited net sampling in order to unveil the origin of acoustic phenomena around the Canary Islands, subtropical northeast Atlantic Ocean. Trawling data revealed a high diversity of fishes, decapods and cephalopods (152 species), although few dominant species likely were responsible for most of the sound scattering in the region. We identified four different acoustic scattering layers in the mesopelagic realm: (1) at 400-500 m depth, a swimbladder resonance phenomenon at 18 kHz produced by gas-bearing migrant fish such as Vinciguerria spp. and Lobianchia dofleini, (2) at 500-600 m depth, a dense 38 kHz layer resulting primarily from the gas-bearing and non-migrant fish Cyclothone braueri, and to a lesser extent, from fluid-like migrant fauna also inhabiting these depths, (3) between 600 and 800 m depth, a weak signal at both 18 and 38 kHz ascribed either to migrant fish or decapods, and (4) below 800 m depth, a weak non-migrant layer at 18 kHz which was not sampled. All the dielly migrating layers reached the epipelagic zone at night, with the shorter-range migrations moving at 4.6 ± 2.6 cm s - 1 and the long-range ones at 11.5 ± 3.8 cm s - 1. This work reduces uncertainties interpreting standard frequencies in mesopelagic studies, while enhances the potential of acoustics for future research and monitoring of the deep pelagic fauna in the Canary Islands.

Dead zone or oasis in the open ocean? Zooplankton distribution and migration in low-oxygen modewater eddies

NASA Astrophysics Data System (ADS)

Hauss, H.; Christiansen, S.; Schütte, F.; Kiko, R.; Edvam Lima, M.; Rodrigues, E.; Karstensen, J.; Löscher, C. R.; Körtzinger, A.; Fiedler, B.

2015-11-01

The eastern tropical North Atlantic (ETNA) features a mesopelagic oxygen minimum zone (OMZ) at approximately 300-600 m depth. Here, oxygen concentrations rarely fall below 40 μmol O2 kg-1, but are thought to decline in the course of climate change. The recent discovery of mesoscale eddies that harbour a shallow suboxic (< 5 μmol O2 kg-1) OMZ just below the mixed layer could serve to identify zooplankton groups that may be negatively or positively affected by on-going ocean deoxygenation. In spring 2014, a detailed survey of a suboxic anticyclonic modewater eddy (ACME) was carried out near the Cape Verde Ocean Observatory (CVOO), combining acoustic and optical profiling methods with stratified multinet hauls and hydrography. The multinet data revealed that the eddy was characterized by an approximately 1.5-fold increase in total area-integrated zooplankton abundance. A marked reduction in acoustic target strength (derived from shipboard ADCP, 75kHz) within the shallow OMZ at nighttime was evident. Acoustic scatterers were avoiding the depth range between about 85 to 120 m, where oxygen concentrations were lower than approximately 20 μmol O2 kg-1, indicating habitat compression to the oxygenated surface layer. This observation is confirmed by time-series observations of a moored ADCP (upward looking, 300 kHz) during an ACME transit at the CVOO mooring in 2010. Nevertheless, part of the diurnal vertical migration (DVM) from the surface layer to the mesopelagic continued through the shallow OMZ. Based upon vertically stratified multinet hauls, Underwater Vision Profiler (UVP5) and ADCP data, four strategies have been identified followed by zooplankton in response to the eddy OMZ: (i) shallow OMZ avoidance and compression at the surface (e.g. most calanoid copepods, euphausiids), (ii) migration to the shallow OMZ core during daytime, but paying O2 debt at the surface at nighttime (e.g. siphonophores, Oncaea spp., eucalanoid copepods), (iii) residing in the shallow OMZ day and night (e.g. ostracods, polychaetes), and iv) DVM through the shallow OMZ from deeper oxygenated depths to the surface and back. For strategy (i), (ii) and (iv), compression of the habitable volume in the surface may increase prey-predator encounter rates, rendering zooplankton more vulnerable to predation and potentially making the eddy surface a foraging hotspot for higher trophic levels. With respect to long-term effects of ocean deoxygenation, we expect zooplankton avoidance of the mesopelagic OMZ to set in if oxygen levels decline below approximately 20 μmol O2 kg-1. This may result in a positive feedback on the OMZ oxygen consumption rates, since zooplankton respiration within the OMZ as well as active flux of dissolved and particulate organic matter into the OMZ will decline.

Dead zone or oasis in the open ocean? Zooplankton distribution and migration in low-oxygen modewater eddies

NASA Astrophysics Data System (ADS)

Hauss, Helena; Christiansen, Svenja; Schütte, Florian; Kiko, Rainer; Edvam Lima, Miryam; Rodrigues, Elizandro; Karstensen, Johannes; Löscher, Carolin R.; Körtzinger, Arne; Fiedler, Björn

2016-04-01

The eastern tropical North Atlantic (ETNA) features a mesopelagic oxygen minimum zone (OMZ) at approximately 300-600 m depth. Here, oxygen concentrations rarely fall below 40 µmol O2 kg-1, but are expected to decline under future projections of global warming. The recent discovery of mesoscale eddies that harbour a shallow suboxic (< 5 µmol O2 kg-1) OMZ just below the mixed layer could serve to identify zooplankton groups that may be negatively or positively affected by ongoing ocean deoxygenation. In spring 2014, a detailed survey of a suboxic anticyclonic modewater eddy (ACME) was carried out near the Cape Verde Ocean Observatory (CVOO), combining acoustic and optical profiling methods with stratified multinet hauls and hydrography. The multinet data revealed that the eddy was characterized by an approximately 1.5-fold increase in total area-integrated zooplankton abundance. At nighttime, when a large proportion of acoustic scatterers is ascending into the upper 150 m, a drastic reduction in mean volume backscattering (Sv) at 75 kHz (shipboard acoustic Doppler current profiler, ADCP) within the shallow OMZ of the eddy was evident compared to the nighttime distribution outside the eddy. Acoustic scatterers avoided the depth range between approximately 85 to 120 m, where oxygen concentrations were lower than approximately 20 µmol O2 kg-1, indicating habitat compression to the oxygenated surface layer. This observation is confirmed by time series observations of a moored ADCP (upward looking, 300 kHz) during an ACME transit at the CVOO mooring in 2010. Nevertheless, part of the diurnal vertical migration (DVM) from the surface layer to the mesopelagic continued through the shallow OMZ. Based upon vertically stratified multinet hauls, Underwater Vision Profiler (UVP5) and ADCP data, four strategies followed by zooplankton in response to in response to the eddy OMZ have been identified: (i) shallow OMZ avoidance and compression at the surface (e.g. most calanoid copepods, euphausiids); (ii) migration to the shallow OMZ core during daytime, but paying O2 debt at the surface at nighttime (e.g. siphonophores, Oncaea spp., eucalanoid copepods); (iii) residing in the shallow OMZ day and night (e.g. ostracods, polychaetes); and (iv) DVM through the shallow OMZ from deeper oxygenated depths to the surface and back. For strategy (i), (ii) and (iv), compression of the habitable volume in the surface may increase prey-predator encounter rates, rendering zooplankton and micronekton more vulnerable to predation and potentially making the eddy surface a foraging hotspot for higher trophic levels. With respect to long-term effects of ocean deoxygenation, we expect avoidance of the mesopelagic OMZ to set in if oxygen levels decline below approximately 20 µmol O2 kg-1. This may result in a positive feedback on the OMZ oxygen consumption rates, since zooplankton and micronekton respiration within the OMZ as well as active flux of dissolved and particulate organic matter into the OMZ will decline.

Changes in zooplankton habitat, behavior, and acoustic scattering characteristics across glider-resolved fronts in the Southern California Current System

NASA Astrophysics Data System (ADS)

Powell, Jesse R.; Ohman, Mark D.

2015-05-01

We report cross-frontal changes in the characteristics of plankton proxy variables measured by autonomous Spray ocean gliders operating within the Southern California Current System (SCCS). A comparison of conditions across the 154 positive frontal gradients (i.e., where density of the surface layer decreased in the offshore direction) identified from six years of continuous measurements showed that waters on the denser side of the fronts typically showed higher Chl-a fluorescence, shallower euphotic zones, and higher acoustic backscatter than waters on the less dense side. Transitions between these regions were relatively abrupt. For positive fronts the amplitude of Diel Vertical Migration (DVM), inferred from a 3-beam 750 kHz acoustic Doppler profiler, increased offshore of fronts and covaried with optical transparency of the water column. Average interbeam variability in acoustic backscatter also changed across many positive fronts within 3 depth strata (0-150 m, 150-400 m, and 400-500 m), revealing a front-related change in the acoustic scattering characteristics of the assemblages. The extent of vertical stratification of distinct scattering assemblages was also more pronounced offshore of positive fronts. Depth-stratified zooplankton samples collected by Mocness nets corroborated the autonomous measurements, showing copepod-dominated assemblages and decreased zooplankton body sizes offshore and euphausiid-dominated assemblages with larger median body sizes inshore of major frontal features.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

2016-04-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

Genome-wide profiling of 24 hr diel rhythmicity in the water flea, Daphnia pulex: network analysis reveals rhythmic gene expression and enhances functional gene annotation.

PubMed

Rund, Samuel S C; Yoo, Boyoung; Alam, Camille; Green, Taryn; Stephens, Melissa T; Zeng, Erliang; George, Gary F; Sheppard, Aaron D; Duffield, Giles E; Milenković, Tijana; Pfrender, Michael E

2016-08-18

Marine and freshwater zooplankton exhibit daily rhythmic patterns of behavior and physiology which may be regulated directly by the light:dark (LD) cycle and/or a molecular circadian clock. One of the best-studied zooplankton taxa, the freshwater crustacean Daphnia, has a 24 h diel vertical migration (DVM) behavior whereby the organism travels up and down through the water column daily. DVM plays a critical role in resource tracking and the behavioral avoidance of predators and damaging ultraviolet radiation. However, there is little information at the transcriptional level linking the expression patterns of genes to the rhythmic physiology/behavior of Daphnia. Here we analyzed genome-wide temporal transcriptional patterns from Daphnia pulex collected over a 44 h time period under a 12:12 LD cycle (diel) conditions using a cosine-fitting algorithm. We used a comprehensive network modeling and analysis approach to identify novel co-regulated rhythmic genes that have similar network topological properties and functional annotations as rhythmic genes identified by the cosine-fitting analyses. Furthermore, we used the network approach to predict with high accuracy novel gene-function associations, thus enhancing current functional annotations available for genes in this ecologically relevant model species. Our results reveal that genes in many functional groupings exhibit 24 h rhythms in their expression patterns under diel conditions. We highlight the rhythmic expression of immunity, oxidative detoxification, and sensory process genes. We discuss differences in the chronobiology of D. pulex from other well-characterized terrestrial arthropods. This research adds to a growing body of literature suggesting the genetic mechanisms governing rhythmicity in crustaceans may be divergent from other arthropod lineages including insects. Lastly, these results highlight the power of using a network analysis approach to identify differential gene expression and provide novel functional annotation.

Impact of collaborative care on survival time for dogs with congestive heart failure and revenue for attending primary care veterinarians.

PubMed

Lefbom, Bonnie K; Peckens, Neal K

2016-07-01

OBJECTIVE To assess the effects of in-person collaborative care by primary care veterinarians (pcDVMs) and board-certified veterinary cardiologists (BCVCs) on survival time of dogs after onset of congestive heart failure (CHF) and on associated revenue for the attending pcDVMs. DESIGN Retrospective cohort study. ANIMALS 26 small-breed dogs treated for naturally occurring CHF secondary to myxomatous mitral valve disease at a multilocation primary care veterinary hospital between 2008 and 2013. PROCEDURES Electronic medical records were reviewed to identify dogs with confirmed CHF secondary to myxomatous mitral valve disease and collect information on patient care, survival time, and pcDVM revenue. Data were compared between dogs that received collaborative care from the pcDVM and a BCVC and dogs that received care from the pcDVM alone. RESULTS Dogs that received collaborative care had a longer median survival time (254 days) than did dogs that received care from the pcDVM alone (146 days). A significant positive correlation was identified between pcDVM revenue and survival time for dogs that received collaborative care (ie, the longer the dog survived, the greater the pcDVM revenue generated from caring for that patient). CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that collaborative care provided to small-breed dogs with CHF by a BCVC and pcDVM could result in survival benefits for affected dogs and increased revenue for pcDVMs, compared with care provided by a pcDVM alone.

Initialization and simulation of a landfalling typhoon using a variational bogus mapped data assimilation (BMDA)

NASA Astrophysics Data System (ADS)

Zhao, Y.; Wang, B.; Wang, Y.

2007-12-01

Recently, a new data assimilation method called “3-dimensional variational data assimilation of mapped observation (3DVM)” has been developed by the authors. We have shown that the new method is very efficient and inexpensive compared with its counterpart 4-dimensional variational data assimilation (4DVar). The new method has been implemented into the Penn State/NCAR mesoscale model MM5V1 (MM5_3DVM). In this study, we apply the new method to the bogus data assimilation (BDA) available in the original MM5 with the 4DVar. By the new approach, a specified sea-level pressure (SLP) field (bogus data) is incorporated into MM5 through the 3DVM (for convenient, we call it variational bogus mapped data assimilation - BMDA) instead of the original 4DVar data assimilation. To demonstrate the effectiveness of the new 3DVM method, initialization and simulation of a landfalling typhoon - typhoon Dan (1999) over the western North Pacific with the new method are compared with that with its counterpart 4DVar in MM5. Results show that the initial structure and the simulated intensity and track are improved more significantly using 3DVM than 4DVar. Sensitivity experiments also show that the simulated typhoon track and intensity are more sensitive to the size of the assimilation window in the 4DVar than that in the 3DVM. Meanwhile, 3DVM takes much less computing cost than its counterpart 4DVar for a given time window.

SU-E-J-87: Building Deformation Error Histogram and Quality Assurance of Deformable Image Registration.

PubMed

Park, S B; Kim, H; Yao, M; Ellis, R; Machtay, M; Sohn, J W

2012-06-01

To quantify the systematic error of a Deformable Image Registration (DIR) system and establish Quality Assurance (QA) procedure. To address the shortfall of landmark approach which it is only available at the significant visible feature points, we adapted a Deformation Vector Map (DVM) comparison approach. We used two CT image sets (R and T image sets) taken for the same patient at different time and generated a DVM, which includes the DIR systematic error. The DVM was calculated using fine-tuned B-Spline DIR and L-BFGS optimizer. By utilizing this DVM we generated R' image set to eliminate the systematic error in DVM,. Thus, we have truth data set, R' and T image sets, and the truth DVM. To test a DIR system, we use R' and T image sets to a DIR system. We compare the test DVM to the truth DVM. If there is no systematic error, they should be identical. We built Deformation Error Histogram (DEH) for quantitative analysis. The test registration was performed with an in-house B-Spline DIR system using a stochastic gradient descent optimizer. Our example data set was generated with a head and neck patient case. We also tested CT to CBCT deformable registration. We found skin regions which interface with the air has relatively larger errors. Also mobile joints such as shoulders had larger errors. Average error for ROIs were as follows; CTV: 0.4mm, Brain stem: 1.4mm, Shoulders: 1.6mm, and Normal tissues: 0.7mm. We succeeded to build DEH approach to quantify the DVM uncertainty. Our data sets are available for testing other systems in our web page. Utilizing DEH, users can decide how much systematic error they would accept. DEH and our data can be a tool for an AAPM task group to compose a DIR system QA guideline. This project is partially supported by the Agency for Healthcare Research and Quality (AHRQ) grant 1R18HS017424-01A2. © 2012 American Association of Physicists in Medicine.

Open Wound Drainage Versus Wound Excision on the Modern Battlefield

DTIC Science & Technology

1988-02-01

Trepical Medicine Marseille, France "DTICS ELECTE R 2 21988 Febnruy 1988 LETTERMAN ARMY INSTITUTE OF RESEARCH PRESIDIO OF SAN FRANCISCO, CALIFORNIA...PERSONALAUTHOR(S)M.L Fackler, MD, JPL Breteau, DVM, LJ Courbil, MD, R . Taxit, DVM, J. Glas, DVM, and J.P. Fievet. MD Il3. TYPE OF REPORT 13b. TIME COVERED 14...Distribution/ AvallabilltY CedeI Aý v Ikv ll 1a nd/o r Dist Special 4L lMOM Fackler et al.--l The body’s reaction to local injury results in

Influence of marine current on vertical migration of Pb in marine bay

NASA Astrophysics Data System (ADS)

Yu, Chen; Hong, Ai; Danfeng, Yang; Huijuan, Zhao; Dongfang, Yang

2018-02-01

This paper analyzed that vertical migration of Pb contents waters in Jiaozhou Bay, and revealed the influence of marine current on vertical migration process. Results showed that Pb contents in bottom waters of Jiaozhou Bay in April and July 1988 were 1.49-18.53 μg L-1 and 12.68/-27.64 μg L-1, respectively. The pollution level of Pb in bottom waters was moderate to heavy, and were showing temporal variations and spatial heterogeneity. The vertical migration process of Pb in April 1988 included a drifting process from the southwest to the north by means of the marine current was rapid in this region. The vertical migration process of Pb in July 1988 in the open waters included no drifting process since the flow rate of marine current was relative low in this region. The vertical migration process of Pb was jointly determined by vertical water’s effect, source input and water exchange, and the influence of marine current on the vertical migration of Pb in marine bay was significant.

The dual DVM/MPH degree at the University of Wisconsin--Madison: a uniquely interdisciplinary collaboration.

PubMed

Olsen, Christopher W; Remington, Patrick L

2008-01-01

The University of Wisconsin-Madison (UWM) launched a new Master of Public Health (MPH) degree program in 2005. This 42-credit MPH degree consists of 18 core and 14 elective course credits, two seminar credits, and eight field project/culminating experience credits. Unique strengths of the program include its strongly interdisciplinary philosophy, encompassing both health science (human medicine, veterinary medicine, pharmacy, nursing) and social science units on campus, and its emphasis on service learning through instructional and field project ties to the public-health community of the state and beyond. To date, the program has admitted 87 students, including full-time students as well as part-time students who continue to work in the health care and/or public-health sectors. The program is currently proceeding with the process for accreditation through the Council for Education in Public Health. In 2007, a formal dual DVM/MPH program was approved to allow students to integrate DVM and MPH training and complete both degrees in a total of five years. Nine MPH students over the first three years of admissions have been individuals affiliated with veterinary medicine (five DVM students and four post-graduate veterinarians).

Turbulence Scale Effects on Heat Transfer in a Linear Turbine Cascade

DTIC Science & Technology

1989-12-01

it. 0.," ," VDI -r’orchungsh,416: 1-2.1 (19.12). hlinze, 1959. Ilinze, J. 0.. Turbilence, an Inhyhtlctim to its Mcchanism and Thcory. New York...0ŕ) CALL IBWRT(dvnjZ, IISPER IOE-611) CALL IBWRT(dvmY., "PRESCAN 2048 ;POSTSCAN 0ŕ) CALL IBWRT(dvm%, "CLWRITE SENSE.321-322;ASCAN ON;SCTRIG SGLŕ

Pressure as a limit to bloater (Coregonus hoyi) vertical migration

USGS Publications Warehouse

TeWinkel, Leslie M.; Fleischer, Guy W.

1998-01-01

Observations of bloater vertical migration showed a limit to the vertical depth changes that bloater experience. In this paper, we conducted an analysis of maximum differences in pressure encountered by bloater during vertical migration. Throughout the bottom depths studied, bloater experienced maximum reductions in swim bladder volume equal to approximately 50-60% of the volume in midwater. The analysis indicated that the limit in vertical depth change may be related to a maximum level of positive or negative buoyancy for which bloater can compensate using alternative mechanisms such as hydrodynamic lift. Bloater may be limited in the extent of migration by either their depth of neutral buoyancy or the distance above the depth of neutral buoyancy at which they can still maintain their position in the water column. Although a migration limit for the bloater population was evident, individual distances of migration varied at each site. These variations in migration distances may indicate differences in depths of neutral buoyancy within the population. However, in spite of these variations, the strong correlation between shallowest depths of migration and swim bladder volume reduction across depths provides evidence that hydrostatic pressure limits the extent of daily vertical movement in bloater.

An Outcome-Based Action Study on Changes in Fitness, Blood Lipids, and Exercise Adherence, Using the Disconnected Values (Intervention) Model

ERIC Educational Resources Information Center

Anshel, Mark H.; Kang, Minsoo

2007-01-01

The authors' purpose in this action study was to examine the effect of a 10-week intervention, using the Disconnected Values Model (DVM), on changes in selected measures of fitness, blood lipids, and exercise adherence among 51 university faculty (10 men and 41 women) from a school in the southeastern United States. The DVM is an intervention…

Vertical migration of municipal wastewater in deep injection well systems, South Florida, USA

NASA Astrophysics Data System (ADS)

Maliva, Robert G.; Guo, Weixing; Missimer, Thomas

2007-11-01

Deep well injection is widely used in South Florida, USA for wastewater disposal largely because of the presence of an injection zone (“boulder zone” of Floridan Aquifer System) that is capable of accepting very large quantities of fluids, in some wells over 75,000 m3/day. The greatest potential risk to public health associated with deep injection wells in South Florida is vertical migration of wastewater, containing pathogenic microorganisms and pollutants, into brackish-water aquifer zones that are being used for alternative water-supply projects such as aquifer storage and recovery. Upwards migration of municipal wastewater has occurred in a minority of South Florida injection systems. The results of solute-transport modeling using the SEAWAT program indicate that the measured vertical hydraulic conductivities of the rock matrix would allow for only minimal vertical migration. Fracturing at some sites increased the equivalent average vertical hydraulic conductivity of confining zone strata by approximately four orders of magnitude and allowed for vertical migration rates of up 80 m/year. Even where vertical migration was rapid, the documented transit times are likely long enough for the inactivation of pathogenic microorganisms.

Dissipation Rate of Turbulent Kinetic Energy in Diel Vertical Migrations: Comparison of ANSYS Fluent Model to Measurements

NASA Astrophysics Data System (ADS)

Dean, Cayla; Soloviev, Alexander; Hirons, Amy; Frank, Tamara; Wood, Jon

2015-04-01

Recent studies suggest that diel vertical migrations of zooplankton may have an impact on ocean mixing, though details are not completely clear. A strong sound scattering layer of zooplankton undergoing diel vertical migrations was observed in Saanich Inlet, British Colombia, Canada by Kunze et al. (2006). In this study, a shipboard 200-kHz echosounder was used to track vertical motion of the sound scattering layer, and microstructure profiles were collected to observe turbulence. An increase of dissipation rate of turbulent kinetic energy by four to five orders of magnitude was measured during diel vertical migrations of zooplankton in one case (but not observed during other cases). A strong sound scattering layer undergoing diel vertical migration was also observed in the Straits of Florida via a bottom mounted acoustic Doppler current profiler at 244 m isobath. A 3-D non-hydrostatic computational fluid dynamics model with Lagrangian particle injections (a proxy for migrating zooplankton) via a discrete phase model was used to simulate the effect of diel vertical migrations on the turbulence for both Saanich Inlet and the Straits of Florida. The model was initialized with idealized (but based on observation) density and velocity profiles. Particles, with buoyancy adjusted to serve as a proxy for vertically swimming zooplankton, were injected to simulate diel vertical migration cycles. Results of models run with extreme concentrations of particles showed an increase in dissipation rate of turbulent kinetic energy of approximately five orders of magnitude over background turbulence during migration of particles in both Saanich Inlet and the Straits of Florida cases (though direct relation of the turbulence produced by buoyant particles and swimming organisms isn't straightforward). This increase was quantitatively consistent, with turbulence measurements by Kunze et al. (2006). When 10 times fewer particles were injected into the model, the effect on dissipation rate of turbulent kinetic energy was an order of magnitude smaller than that from the extreme concentration. At a concentration of particles 100 times smaller than the extreme concentration, there was no longer an observable effect. In the Straits of Florida, direct turbulence measurements were not available to make a quantitative comparison. However, a small, but statistically significant decrease in northward current velocity profiles during migration times were observed after averaging these profiles over 11 months. A small decrease of current velocity connected to the vertical migrations of particles was reproduced in the Straits of Florida model case. The deviations in the velocity profiles can be explained by the increase in turbulent mixing during vertical migration periods.

The disconnected values model improves mental well-being and fitness in an employee wellness program.

PubMed

Anshel, Mark H; Brinthaupt, Thomas M; Kang, Minsoo

2010-01-01

This study examined the effect of a 10-week wellness program on changes in physical fitness and mental well-being. The conceptual framework for this study was the Disconnected Values Model (DVM). According to the DVM, detecting the inconsistencies between negative habits and values (e.g., health, family, faith, character) and concluding that these "disconnects" are unacceptable promotes the need for health behavior change. Participants were 164 full-time employees at a university in the southeastern U.S. The program included fitness coaching and a 90-minute orientation based on the DVM. Multivariate Mixed Model analyses indicated significantly improved scores from pre- to post-intervention on selected measures of physical fitness and mental well-being. The results suggest that the Disconnected Values Model provides an effective cognitive-behavioral approach to generating health behavior change in a 10-week workplace wellness program.

Trophic transfer of microcystins through the lake pelagic food web: evidence for the role of zooplankton as a vector in fish contamination.

PubMed

Sotton, Benoît; Guillard, Jean; Anneville, Orlane; Maréchal, Marjorie; Savichtcheva, Olga; Domaizon, Isabelle

2014-01-01

An in situ study was performed to investigate the role of zooplankton as a vector of microcystins (MCs) from Planktothrix rubescens filaments to fish during a metalimnic bloom of P. rubescens in Lake Hallwil (Switzerland). The concentrations of MCs in P. rubescens and various zooplanktonic taxa (filter-feeders and predators) were assessed in different water strata (epi-, meta- and hypolimnion) using replicated sampling over a 24-hour survey. The presence of P. rubescens in the gut content of various zooplanktonic taxa (Daphnia, Bosmina and Chaoborus) was verified by targeting the cyanobacterial nucleic acids (DNA). These results highlighted that cyanobacterial cells constitute a part of food resource for herbivorous zooplanktonic taxa during metalimnic bloom periods. Furthermore, presence of MCs in Chaoborus larvae highlighted the trophic transfer of MCs between herbivorous zooplankton and their invertebrate predators. Our results suggest that zooplanktonic herbivores by diel vertical migration (DVM) act as vectors of MCs by encapsulating grazed cyanobacteria. As a consequence, they largely contribute to the contamination of zooplanktonic predators, and in fine of zooplanktivorous whitefish. Indeed, we estimated the relative contribution of three preys of the whitefish (i.e. Daphnia, Bosmina and Chaoborus) to diet contamination. We showed that Chaoborus and Daphnia were the highest contributor as MC vectors in the whitefish diet (74.6 and 20.5% of MC-LR equivalent concentrations, respectively). The transfer of MCs across the different trophic compartments follows complex trophic pathways involving various trophic levels whose relative importance in fish contamination might vary at daily and seasonal scale. © 2013.

Delayed visual attention caused by high myopic refractive error.

PubMed

Winges, Kimberly M; Zarpellon, Ursula; Hou, Chuan; Good, William V

2005-06-01

Delayed visual maturation (DVM) is usually a retrospective diagnosis given to infants who are born with no or poor visually-directed behavior, despite normal acuity on objective testing, but who recover months later. This condition can be organized into several types based on associated neurodevelopmental or ocular findings, but the etiology of DVM is probably complex and involves multiple possible origins. Here we report two infants who presented with delayed visual maturation (attention). They were visually unresponsive at birth but were later found to have high myopic errors. Patient 1 had -4 D right eye, -5 D left eye. Patient 2 had -9 D o.u. Upon spectacle correction at 5 and 4 months, respectively, both infants immediately displayed visually-directed behavior, suggesting that a high refractive error was the cause of inattention in these patients. These findings could add to knowledge surrounding DVM and the diagnosis of apparently blind infants. Findings presented here also indicate the importance of prompt refractive error measurement in such cases.

Magnetosensitive neurons mediate geomagnetic orientation in Caenorhabditis elegans

PubMed Central

Vidal-Gadea, Andrés; Ward, Kristi; Beron, Celia; Ghorashian, Navid; Gokce, Sertan; Russell, Joshua; Truong, Nicholas; Parikh, Adhishri; Gadea, Otilia; Ben-Yakar, Adela; Pierce-Shimomura, Jonathan

2015-01-01

Many organisms spanning from bacteria to mammals orient to the earth's magnetic field. For a few animals, central neurons responsive to earth-strength magnetic fields have been identified; however, magnetosensory neurons have yet to be identified in any animal. We show that the nematode Caenorhabditis elegans orients to the earth's magnetic field during vertical burrowing migrations. Well-fed worms migrated up, while starved worms migrated down. Populations isolated from around the world, migrated at angles to the magnetic vector that would optimize vertical translation in their native soil, with northern- and southern-hemisphere worms displaying opposite migratory preferences. Magnetic orientation and vertical migrations required the TAX-4 cyclic nucleotide-gated ion channel in the AFD sensory neuron pair. Calcium imaging showed that these neurons respond to magnetic fields even without synaptic input. C. elegans may have adapted magnetic orientation to simplify their vertical burrowing migration by reducing the orientation task from three dimensions to one. DOI: http://dx.doi.org/10.7554/eLife.07493.001 PMID:26083711

A Centralized Source of Information for the Military Working Dog Program

DTIC Science & Technology

1990-06-01

USA B.S., Purdue University, 1975 MS., Oklahoma State University, 1978 D TIC D.V.M., Colorado State University, 1982 NOV2 6 1990 SI D Fort...FROST, MAJ, USA D A"C "BU~n ancno un ced i B.S., Purdue University, 1975 aUsti c tio M.S., Oklahoma State University, 1978 - D.V.M., Colorado State...19-35: 2, 11-27; Thorton). Narcotic Detector Dog - A MWD trained specifically to detect the presence of marijuana and its derivatives. They are also

Vertical migration and nighttime distribution of adult bloaters in Lake Michigan

USGS Publications Warehouse

TeWinkel, Leslie M.; Fleischer, Guy W.

1999-01-01

The vertical migration and nighttime vertical distribution of adult bloaters Coregonus hoyi were investigated during late summer in Lake Michigan using acoustics simultaneously with either midwater or bottom trawling. Bloaters remained on or near bottom during the day. At night, bloaters were distributed throughout 30-65 m of water, depending on bottom depth. Shallowest depths of migration were not related to water temperature or incident light. Maximum distances of migration increased with increasing bottom depth. Nighttime midwater densities ranged from 0.00 to 6.61 fish/1,000 mA? and decreased with increasing bottom depth. Comparisons of length distributions showed that migrating and nonmigrating bloaters did not differ in size. However, at most sites, daytime bottom catches collected a greater proportion of larger individuals compared with nighttime midwater or bottom catches. Mean target strengths by 5-m strata indicated that migrating bloaters did not stratify by size in the water column at night. Overall, patterns in frequency of empty stomachs and mean digestive state of prey indicated that a portion of the bloater population fed in the water column at night. Bloater diet composition indicated both midwater feeding and bottom feeding. In sum, although a portion of the bloater population fed in the water column at night, bloaters were not limited to feeding at this time. This research confirmed that bloaters are opportunistic feeders and did not fully support the previously proposed hypothesis that bloater vertical migration is driven by the vertically migrating macroinvertebrate the opossom shrimp Mysis relicta.

Do Daphnia use metalimnetic organic matter in a north temperate lake? An analysis of vertical migration

USGS Publications Warehouse

Brosseau, Chase Julian; Cline, Timothy J.; Cole, Jonathan J.; Hodgson, James R.; Pace, Michael L.; Weidel, Brian C.

2012-01-01

Diel vertical migration of zooplankton is influenced by a variety of factors including predation, food, and temperature. Research has recently shifted from a focus on factors influencing migration to how migration affects nutrient cycling and habitat coupling. Here we evaluate the potential for Daphnia migrations to incorporate metalimnetic productivity in a well-studied northern Wisconsin lake. We use prior studies conducted between 1985 and 1990 and current diel migration data (2008) to compare day and night Daphnia vertical distributions with the depth of the metalimnion (between the thermocline and 1% light depth). Daphnia migrate from a daytime mean residence depth of between about 1.7 and 2.5 m to a nighttime mean residence depth of between 0 and 2.0 m. These migrations are consistent between the prior period and current measurements. Daytime residence depths of Daphnia are rarely deep enough to reach the metalimnion; hence, metalimnetic primary production is unlikely to be an important resource for Daphnia in this system.

Fine Scale Baleen Whale Behavior Observed via Tagging Over Daily Time Scales

DTIC Science & Technology

2012-09-30

right whales and sei whales) and the diel vertical migration behavior of their copepod prey. I hypothesize that (1) right whales track the diel...vertical migration of copepods by feeding near the bottom during the day and at the surface at night, and (2) sei whales are unable to feed on copepods at...depth during the day, and are therefore restricted to feeding on copepods at the surface only. Because copepod diel vertical migration is variable

Fine Scale Baleen Whale Behavior Observed via Tagging Over Daily Time Scales

DTIC Science & Technology

2013-09-30

sei whales) and the diel vertical migration behavior of their copepod prey. I hypothesize that (1) right whales track the diel vertical migration of... copepods by feeding near the bottom during the day and at the surface at night, and (2) sei whales are unable to feed on copepods at depth during the...day, and are therefore restricted to feeding on copepods at the surface only. Because copepod diel vertical migration is variable over time (days to

An analysis of numerical convergence in discrete velocity gas dynamics for internal flows

NASA Astrophysics Data System (ADS)

Sekaran, Aarthi; Varghese, Philip; Goldstein, David

2018-07-01

The Discrete Velocity Method (DVM) for solving the Boltzmann equation has significant advantages in the modeling of non-equilibrium and near equilibrium flows as compared to other methods in terms of reduced statistical noise, faster solutions and the ability to handle transient flows. Yet the DVM performance for rarefied flow in complex, small-scale geometries, in microelectromechanical (MEMS) devices for instance, is yet to be studied in detail. The present study focuses on the performance of the DVM for locally large Knudsen number flows of argon around sharp corners and other sources for discontinuities in the distribution function. Our analysis details the nature of the solution for some benchmark cases and introduces the concept of solution convergence for the transport terms in the discrete velocity Boltzmann equation. The limiting effects of the velocity space discretization are also investigated and the constraints on obtaining a robust, consistent solution are derived. We propose techniques to maintain solution convergence and demonstrate the implementation of a specific strategy and its effect on the fidelity of the solution for some benchmark cases.

Measurements of fluid transport by controllable vertical migrations of plankton

NASA Astrophysics Data System (ADS)

Houghton, Isabel A.; Dabiri, John O.

2016-11-01

Diel vertical migration of zooplankton has been proposed to be a significant contributor to local and possibly large-scale fluid transport in the ocean. However, studies of this problem to date have been limited to order-of-magnitude estimates based on first principles and a small number of field observations. In this work, we leverage the phototactic behavior of zooplankton to stimulate controllable vertical migrations in the laboratory and to study the associated fluid transport and mixing. Building upon a previous prototype system, a laser guidance system induces vertical swimming of brine shrimp (Artemia salina) in a 2.1 meter tall, density-stratified water tank. The animal swimming speed and spacing during the controlled vertical migration is characterized with video analysis. A schlieren imaging system is utilized to visualize density perturbations to a stable stratification for quantification of fluid displacement length scales and restratification timescales. These experiments can add to our understanding of the dynamics of active particles in stratified flows. NSF and US-Israel Binational Science Foundation.

Reverse time migration in tilted transversely isotropic media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Linbing; Rector III, James W.; Hoversten, G. Michael

2004-07-01

This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength inmore » the vertical direction and 1.5 wavelength in the lateral direction.« less

An implicit scheme with memory reduction technique for steady state solutions of DVBE in all flow regimes

NASA Astrophysics Data System (ADS)

Yang, L. M.; Shu, C.; Yang, W. M.; Wu, J.

2018-04-01

High consumption of memory and computational effort is the major barrier to prevent the widespread use of the discrete velocity method (DVM) in the simulation of flows in all flow regimes. To overcome this drawback, an implicit DVM with a memory reduction technique for solving a steady discrete velocity Boltzmann equation (DVBE) is presented in this work. In the method, the distribution functions in the whole discrete velocity space do not need to be stored, and they are calculated from the macroscopic flow variables. As a result, its memory requirement is in the same order as the conventional Euler/Navier-Stokes solver. In the meantime, it is more efficient than the explicit DVM for the simulation of various flows. To make the method efficient for solving flow problems in all flow regimes, a prediction step is introduced to estimate the local equilibrium state of the DVBE. In the prediction step, the distribution function at the cell interface is calculated by the local solution of DVBE. For the flow simulation, when the cell size is less than the mean free path, the prediction step has almost no effect on the solution. However, when the cell size is much larger than the mean free path, the prediction step dominates the solution so as to provide reasonable results in such a flow regime. In addition, to further improve the computational efficiency of the developed scheme in the continuum flow regime, the implicit technique is also introduced into the prediction step. Numerical results showed that the proposed implicit scheme can provide reasonable results in all flow regimes and increase significantly the computational efficiency in the continuum flow regime as compared with the existing DVM solvers.

Seasonally dynamic diel vertical migrations of Mysis diluviana, coregonine fishes, and siscowet lake trout in the pelagia of western Lake Superior

USGS Publications Warehouse

Ahrenstorff, Tyler D.; Hrabik, Thomas R.; Stockwell, Jason D.; Yule, Daniel L.; Sass, Greg G.

2011-01-01

Diel vertical migrations are common among many aquatic species and are often associated with changing light levels. The underlying mechanisms are generally attributed to optimizing foraging efficiency or growth rates and avoiding predation risk (μ). The objectives of this study were to (1) assess seasonal and interannual changes in vertical migration patterns of three trophic levels in the Lake Superior pelagic food web and (2) examine the mechanisms underlying the observed variability by using models of foraging, growth, and μ. Our results suggest that the opossum shrimp Mysis diluviana, kiyi Coregonus kiyi, and siscowet lake trout Salvelinus namaycush migrate concurrently during each season, but spring migrations are less extensive than summer and fall migrations. In comparison with M. diluviana, kiyis, and siscowets, the migrations by ciscoes C. artedi were not as deep in the water column during the day, regardless of season. Foraging potential and μ probably drive the movement patterns of M. diluviana, while our modeling results indicate that movements by kiyis and ciscoes are related to foraging opportunity and growth potential and receive a lesser influence from μ. The siscowet is an abundant apex predator in the pelagia of Lake Superior and probably undertakes vertical migrations in the water column to optimize foraging efficiency and growth. The concurrent vertical movement patterns of most species are likely to facilitate nutrient transport in this exceedingly oligotrophic ecosystem, and they demonstrate strong linkages between predators and prey. Fishery management strategies should use an ecosystem approach and should consider how altering the densities of long-lived top predators produces cascading effects on the nutrient cycling and energy flow in lower trophic levels.

The Investigation of the Fundamental Limits of Heterodyne Holographic Interferometry with the Application of Imaging Laser Generated Lamb Waves

DTIC Science & Technology

1989-04-01

character*25 msg,echol,echo2,msgl character* 12 fname,vel,stepl,step2 character dvm(15),decl,dec2 integer numl,num2,row,col, icheck ,fig real data C fig...flg) linex = ’ send step2 error’ if (flg.ne.0) goto 8000 write (*,610) step2,echol c c 200 icheck = 0 c c ENTER FILE NAME c write (*,’(A/)’)’ Specify...dvm, data) write (*,660) i, icheck write (*,600) data write (3,640) data c c Increment Horizontal Position c msg - ’I1"’ call send855 (msg,echo 1,flg

An improved cost-effective, reproducible method for evaluation of bone loss in a rodent model.

PubMed

Fine, Daniel H; Schreiner, Helen; Nasri-Heir, Cibele; Greenberg, Barbara; Jiang, Shuying; Markowitz, Kenneth; Furgang, David

2009-02-01

This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis. Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased. Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p<0.05). The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.

Observation method to predict meander migration and vertical degradation of rivers.

DOT National Transportation Integrated Search

2014-05-01

Meander migration and vertical degradation of river bed are processes that have been studied for years. : Different methods have been proposed to make predictions of the behavior of rivers with respect to these : processes. These two erosion controll...

Vertical migration of Karenia brevis in the northeastern Gulf of Mexico observed from glider measurements.

PubMed

Hu, Chuanmin; Barnes, Brian B; Qi, Lin; Lembke, Chad; English, David

2016-09-01

The toxic marine dinoflagellate, Karenia brevis (the species responsible for most of red tides or harmful algal blooms in the Gulf of Mexico), is known to be able to swim vertically to adapt to the light and nutrient environments, nearly all such observations have been made through controlled experiments using cultures. Here, using continuous 3-dimensional measurements by an ocean glider across a K. brevis bloom in the northeastern Gulf of Mexico between 1 and 8 August 2014, we show the vertical migration behavior of K. brevis. Within the bloom where K. brevis concentration is between 100,000 and 1,000,000cellsL -1 , the stratified water shows a two-layer system with the depth of pycnocline ranging between 14-20m and salinity and temperature in the surface layer being <34.8 and >28°C, respectively. The bottom layer shows the salinity of >36 and temperature of <26°C. The low salinity is apparently due to coastal runoff, as the top layer also shows high amount of colored dissolved organic matter (CDOM). Within the top layer, chlorophyll-a fluorescence shows clear diel changes in the vertical structure, an indication of K. brevis vertical migration at a mean speed of 0.5-1mh -1 . The upward migration appears to start at sunrise at a depth of 8-10m, while the downward migration appears to start at sunset (or when surface light approaches 0) at a depth of ∼2m. These vertical migrations are believed to be a result of the need of K. brevis cells for light and nutrients in a stable, stratified, and CDOM-rich environment. Copyright © 2016 Elsevier B.V. All rights reserved.

The Dynamics of Vertical Migration in the Oceanic Gulf of Mexico after Deepwater Horizon: Active Linkage of Large Vertebrates and Deep-Pelagic Nekton

NASA Astrophysics Data System (ADS)

Sutton, T.; Cook, A.; Frank, T. M.; Boswell, K. M.; Vecchione, M.; Judkins, H.; Romero, I.

2016-02-01

Toothed whales, smaller cetaceans, seabirds, and epipelagic gamefishes rely on deep-pelagic (meso- and bathypelagic) nekton as primary or secondary prey. This trophic interaction is mediated by downward and upward vertical movements (e.g., sperm whale diving and lanternfishes migration, respectively). This interaction also links particle-feeding lower trophic levels with top predators in a manner that spans the gamut of depth domains. This is particularly important with respect to a whole-water column disturbance such as the Deepwater Horizon oil spill (DWHOS). Here we present highly resolved vertical distribution and migration data collected during a large-scale, NOAA-supported, deep-pelagic (0-1500 m) survey in 2011, along with data collected during ongoing GoMRI-supported DEEPEND consortium surveys. The deep-pelagic nekton community of the Gulf of Mexico is a complex mixture of migrating, non-migrating, and partially migrating assemblages that connect surface waters with depths in excess of 1000 m. Major patterns of vertical distribution for 400+ species of fishes, cephalopods, and macrocrustaceans, the primary prey of many important species of oceanic vertebrates living near-surface, will be summarized and quantified with the goal of highlighting potential vectors of anthropogenic contamination transfer in the deep-pelagial, the Gulf's largest ecosystem.

Vertical migration of motile phytoplankton chains through turbulence

NASA Astrophysics Data System (ADS)

Climent, Eric; Lovecchio, Salvatore; Durham, William; Stocker, Roman

2017-11-01

Daily, phytoplankton needs to migrate vertically from and towards the ocean surface to find nutrients such as dissolved oxygen. To travel through the water column they need to fight against gravity (by swimming) and fluid turbulence which can make their journey longer. It is often observed that cells migrate across the water column as chains. The first benefit to form chains is that micro-organisms sum up their thrust while reducing their drag. Therefore, upwards swimming is faster for chains in a quiescent fluid with steady vertical orientation. However, as chain length increases their tendency to periodically tumble in turbulent structures increases which reduces orientation stability and limits their capacity to swim upwards. The purpose of our study is to elaborate on this apparent contradiction. We carried out direct numerical simulations and physical analysis of the coupled system of homogeneous isotropic turbulence and chain trajectories through Lagrangian tracking. Formation of chains is indeed favorable for vertical migration through the upper layer of the ocean.

Buoyancy characteristics of the bloater (Coregonus hoyi) in relation to patterns of vertical migration and acoustic backscattering

USGS Publications Warehouse

Fleischer, Guy W.; TeWinkel, Leslie M.

1998-01-01

Acoustic studies in Lake Michigan found that bloaters (Coregonus hoyi) were less reflective per size than the other major pelagic species. This difference in in situ acoustic backscattering could indicate that the deep-water bloaters have compressed swimbladders for much of their vertical range with related implications on buoyancy. To test this hypothesis, the buoyancy characteristics of bloaters were determined with fish placed in a cage that was lowered to bottom and monitored with an underwater camera. We found bloaters were positively buoyant near surface, neutrally buoyant at intermediate strata, and negatively buoyant near bottom. This pattern was consistent for the range of depths bloaters occur. The depth of neutral buoyancy (near the 50-n strata) corresponds with the maximum extent of vertical migration for bloaters observed in acoustic surveys. Fish below this depth would be negatively buoyant which supports our contention that bloaters deeper in the water column have compressed swimbladders. Understanding the buoyancy characteristics of pelagic fishes will help to predict the effects of vertical migration on target strength measurement and confirms the use of acoustics as a tool to identify and quantify the ecological phenomenon of vertical migration.

On the ultrafast charge migration and subsequent charge directed reactivity in Cl⋯N halogen-bonded clusters following vertical ionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandra, Sankhabrata; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in; Periyasamy, Ganga

2015-06-28

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH{sub 2}, CF{sub 3}, and COOH substituents) molecules paired with NH{sub 3} (referred as ACl:NH{sub 3} complex): these complexes exhibit halogen bonds. To the best of our knowledge, this ismore » the first report on purely electron correlation- and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31 + G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl⋯NH{sub 3} complex, the hole is predicted to migrate from the NH{sub 3}-end to the ClCN-end of the NCCl⋯NH{sub 3} complex in approximately 0.5 fs on the D{sub 0} cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H{sub 2}NCl:NH{sub 3}, F{sub 3}CCl:NH{sub 3}, and HOOCCl:NH{sub 3}, exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH{sub 3} and HOCl:NH{sub 3} complexes do not exhibit any charge migration following vertical ionization to the D{sub 0} cation state, pointing to interesting halogen bond strength-dependent charge migration.« less

Delayed visual maturation in infants: a disorder of figure-ground separation?

PubMed

Harris, C M; Kriss, A; Shawkat, F; Taylor, D; Russell-Eggitt, I

1996-01-01

Delayed visual maturation (DVM) is characterised by visual unresponsiveness in early infancy, which subsequently improves spontaneously to normal levels. We studied the optokinetic response and recorded pattern reversal VEPs in six infants with DVM (aged 2-4 months) when they were at the stage of complete visual unresponsiveness. Although no saccades or visual tracking with the eyes or head could be elicited to visual objects, a normal full-field rapid buildup OKN response occurred when viewing biocularly or during monocular stimulation in the temporo-nasal direction of the viewing eye. Almost no monocular OKN could be elicited in the naso-temporal direction, which was significantly poorer than normal age-matched infants. No OKN quick phases were missed, and there were no other signs of "ocular motor apraxia." VEPs were normal in amplitude and latency for age. It appears, therefore, that infants with DVM are delayed in orienting to local regions of the visual field, but can respond to full-field motion. The presence of normal OKN quick-phases and slow-phases suggests normal brain stem function, and the presence of normal pattern VEPs suggests a normal retino-geniculo-striate pathway. These oculomotor and electrophysiological findings suggest delayed development of extra-striate cortical structures, possibly involving either an abnormality in figure-ground segregation or in attentional pathways.

Cellular behavior controlled by bio-inspired and geometry-tunable nanohairs.

PubMed

Heo, Chaejeong; Jeong, Chanho; Im, Hyeon Seong; Kim, Jong Uk; Woo, Juhyun; Lee, Ji Yeon; Park, Byeonghak; Suh, Minah; Kim, Tae-Il

2017-11-23

A cicada wing has a biocidal feature of rupturing the membrane of cells, while the cactus spine can transmit a water drop to the stem of the plant. Both of these properties have evolved from their respective unique structures. Here, we endeavor to develop geometry-controllable nanohairs that mimic the cicada's wing-like vertical hairs and the cactus spine-like stooped hairs, and to quantitatively characterize the cell migration behavior of the hairy structures. It was found that the neuroblastoma cells are highly sensitive to the variation of surfaces: flat, vertical, and stooped nanohairs (100 nm diameter and 900 nm height). The cells on the vertical hairs showed significantly decreased proliferation. It was found that the behavior of cells cultured on stooped nanohairs is strongly influenced by the direction of the stooped pattern of hairs when we quantitatively measured the migration of cells on flat, vertical, and stooped structures. However, the cells on the flat structures showed random movement and the cells on the vertical nanohairs restricted the nanohair movement. Cells on the stooped structure showed higher forward migration preference compared to that of the other structures. Furthermore, we found that these cellular behaviors on the different patterns of nanohairs were affected by intracellular actin flament change. Consistent with these results, the vertical and stooped structures can facilitate the control of cell viability and guide directional migration for biomedical applications such as organogenesis.

Twenty-year follow-up study of radiocesium migration in soil.

PubMed

Clouvas, A; Xanthos, S; Takoudis, G; Antonopoulos-Domis, M; Zinoviadis, G; Vidmar, T; Likar, A

2007-01-01

The profile of (137)Cs present in undisturbed soil due to the Chernobyl accident was measured repeatedly for approximately 20 y. The vertical migration of (137)Cs in soil is a very slow process. The mean vertical migration velocity is estimated at approximately 0.1-0.2 cm y(-1). A method based on in situ gamma spectrometry measurements and Monte Carlo computations, aimed at estimating the profile of (137)Cs without performing any soil sampling, is investigated.

Abundance, biomass, vertical migration and estimated development rate of the copepod Calanus finmarchicus in the southern Gulf of Maine during late spring

NASA Astrophysics Data System (ADS)

Durbin, Edward G.; Gilman, Sharon L.; Campbell, Robert G.; Durbin, Ann G.

Abundance, biomass, diel vertical migration and estimated in situ development in the copepod Calanus finmarchicus were investigated during late spring in 1988 and 1989 in the southern Gulf of Maine. This region is an important feeding ground for the planktivorous right whale, Eubalaena glacialis. The 1988 study took place during the declining spring bloom, with phytoplankton biomass variable, but relatively high. The 1989 study occurred after seasonal stratification, and phytoplankton biomass was low. During the 1988 cruise the dominant stage in C. finmarchicus shifted from C1-C2 to C4-C5. Stage durations during 1988 (4.0 days for C3 and 6.6 days for C4), estimated from the temporal change in stage distribution, were similar to maximal values observed in the laboratory. In contrast, during 1989 stages C4 and C5 were dominant throughout the study period and development rate was slow (estimated C4 stage duration about 24 days). Diel vertical migration patterns changed, from an absence of migration at the first two 1988 stations where younger stages predominated (C1-C3), to a very strong diel vertical migration at the later 1988 stations where stages C3-C3 predominated. This was not a simple ontogenetic change in migratory behavior since all copepodite stages at each station showed similar patterns. During 1989 dense aggregations of C. finmarchicus remained in the surface layer both day and night, and no diel vertical migration was observed. A small, nonmigratory population of late-stage C. finmarchicus was found at depth. Individual body size of these copepods was considerably greater than those found at the surface. Differences in development rate between years reflect differences in the food environment, brought about by seasonal hydrographic changes and the development of more intense stratification. Diel vertical migration patterns, however, did not show a simple relation with food availability, and it is suggested that predation may play an important role in regulating the behavior of the copepods.

VIIRS captures phytoplankton vertical migration in the NE Gulf of Mexico.

PubMed

Qi, Lin; Hu, Chuanmin; Barnes, Brian B; Lee, Zhongping

2017-06-01

In summer 2014, a toxic Karenia brevis bloom (red tide) occurred in the NE Gulf of Mexico, during which vertical migration of K. brevis has been observed from glider measurements. The current study shows that satellite observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) can capture changes in surface reflectance and chlorophyll concentration occurring within 2h, which may be attributed this K. brevis vertical migration. The argument is supported by earlier glider measurements in the same bloom, by the dramatic changes in the VIIRS-derived surface chlorophyll, and by the consistency between the short-term reflectance changes and those reported earlier from field-measured K. brevis vertical migration. Estimates using the quasi-analytical algorithm also indicate significant increases in both total absorption coefficient and backscattering coefficient in two hours. The two observations in a day from a single polar-orbiting satellite sensor are thus shown to be able to infer phytoplankton vertical movement within a short timeframe, a phenomenon difficult to capture with other sensors as each sensor can provide at most one observation per day, and cross-sensor inconsistency may make interpretation of merged-sensor data difficult. These findings strongly support geostationary satellite missions to study short-term bloom dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling the transport of common sole larvae in the southern North Sea: Influence of hydrodynamics and larval vertical movements

NASA Astrophysics Data System (ADS)

Savina, Marie; Lacroix, Geneviève; Ruddick, Kevin

2010-04-01

In the present work we used a particle-tracking model coupled to a 3D hydrodynamic model to study the combined effect of hydrodynamic variability and active vertical movements on the transport of sole larvae in the southern North Sea. Larval transport from the 6 main spawning grounds was simulated during 40 day periods starting on 2 plausible spawning dates, the 15/04 and the 01/05, during 2 years, 1995 and 1996. In addition to a "passive" behaviour, 3 types of active vertical movements inspired from previous studies have been tested: (1) Eggs and early larvae float in the surface waters, late larvae migrate toward the bottom and stay there until the end of the simulation; (2 and 3) Eggs float in the surface waters, early larvae perform diel vertical migrations in the surface waters, and (2) Late larvae perform diel vertical migrations in the bottom waters until the end of the simulation; or (3) Late larvae perform tidally synchronised vertical migrations in the bottom waters until the end of the simulation. These behaviours have been implemented in the model with vertical migration rates, positive or negative, which can account for buoyancy or real swimming activity. Variations in larval transport were analysed in terms of mean trajectories, final larvae distribution, larval retention above nurseries, and connectivity. Results suggest that the variations in larval retention above nurseries due to the varying hydrodynamic conditions are not consistent in space i.e. not the same for all the spawning sites. The effect of active vertical movements on larval transport is also not consistent in space: Effects of active vertical movements include decreased retention above nurseries, decreased transport and/or decreased horizontal dispersion of larvae through reduced vertical shear (depending on the zone). The variability in larval retention due to hydrodynamic variability is higher than variability due to differences in the behaviour of larvae. In terms of connectivity, exchanges of larvae between the 6 areas considered are moderate: 10 connections happened out of the 30 possible, and the amount of larvae exchanged is much lower than the amount of larvae retained except in a few cases. This is not incompatible with the possible existence of subpopulations of sole in the Eastern Channel and southern North Sea.

Experimental comparison of icing cloud instruments

NASA Technical Reports Server (NTRS)

Olsen, W.; Takeuchi, D. M.; Adams, K.

1983-01-01

Icing cloud instruments were tested in the spray cloud Icing Research Tunnel (IRT) in order to determine their relative accuracy and their limitations over a broad range of conditions. It was found that the average of the readings from each of the liquid water content (LWC) instruments tested agreed closely with each other and with the IRT calibration; but all have a data scatter (+ or - one standard deviation) of about + or - 20 percent. The effect of this + or - 20 percent uncertainty is probably acceptable in aero-penalty and deicer experiments. Existing laser spectrometers proved to be too inaccurate for LWC measurements. The error due to water runoff was the same for all ice accretion LWC instruments. Any given laser spectrometer proved to be highly repeatable in its indications of volume median drop size (DVM), LWC and drop size distribution. However, there was a significant disagreement between different spectrometers of the same model, even after careful standard calibration and data analysis. The scatter about the mean of the DVM data from five Axial Scattering Spectrometer Probes was + or - 20 percent (+ or - one standard deviation) and the average was 20 percent higher than the old IRT calibration. The + or - 20 percent uncertainty in DVM can cause an unacceptable variation in the drag coefficient of an airfoil with ice; however, the variation in a deicer performance test may be acceptable.

Vertical distributions and diel migrations of Euthecosomata in the northwest Sargasso Sea

NASA Astrophysics Data System (ADS)

Wormuth, John H.

1981-12-01

Vertical distributions and seasonal variations in abundance of nine abundant or frequent pteropod species or subspecies in the northwest Sargasso Sea are described. Factor analyses yielded two groups, diel migrators and non-migrators. In terms of water column abundances, tows taken in August and November are similar, as are tows in December and April. Most species show significant within-species agreement in depth distribution over the year but high variability in abundance. Regression analyses using environmental parameters as independent variables show significant correlations of species abundances with temperature.

Species-specific patterns of diel migration into the Oxygen Minimum Zone by euphausiids in the Humboldt Current Ecosystem

NASA Astrophysics Data System (ADS)

Antezana, Tarsicio

2009-12-01

A series of stratified bongo net samples taken over a 2 day period at ca. 18°S, about 20 nm off the coast of Peru, South America, suggest species-specific patterns of diel vertical migration into the Oxygen Minimum Zone (OMZ) of the Humboldt Current Ecosystem (HCE). The OMZ was the most dramatic feature of the water column and seemed to determine the extent of migration: Stylocheiron affine migrated only to the shallow oxycline; whereas Euphausia mucronata, Euphausia eximia, Euphausia distinguenda and Euphausia tenera migrated to the core of the OMZ; and Nematoscelis gracilis to beneath the core of the OMZ. Some differences were also found in the timing and duration of the ascent and descent, and residence times in shallow and deep layers. E. mucronata, N. gracilis and E. distinguenda displayed a normal descent during sunrise, and ascent during sunset. E. eximia and E. tenera also descended during sunrise but seemed to begin their ascent earlier in the afternoon and consequently shortened their deep residence times. S. affine showed the most extended residence times at the shallow layer and the shortest vertical displacement. Day and night vertical stratification and differences in the timing of migration into and out of the OMZ of the HCE suggest a community structure based on habitat partitioning whereby species avoided co-occurrence in time and space. Species-specific patterns of vertical stratification and migratory chronology are examined with regard to body and gill sizes, feeding adaptations of euphausiids, and potential food resources at the OMZ.

Wide-angle Marine Seismic Refraction Imaging of Vertical Faults: Pre-Stack Turning Wave Migrations of Synthetic Data and Implications for Survey Design

NASA Astrophysics Data System (ADS)

Miller, N. C.; Lizarralde, D.; McGuire, J.; Hole, J. A.

2006-12-01

We consider methodologies, including survey design and processing algorithms, which are best suited to imaging vertical reflectors in oceanic crust using marine seismic techniques. The ability to image the reflectivity structure of transform faults as a function of depth, for example, may provide new insights into what controls seismicity along these plate boundaries. Turning-wave migration has been used with success to image vertical faults on land. With synthetic datasets we find that this approach has unique difficulties in the deep ocean. The fault-reflected crustal refraction phase (Pg-r) typically used in pre-stack migrations is difficult to isolate in marine seismic data. An "imagable" Pg-r is only observed in a time window between the first arrivals and arrivals from the sediments and the thick, slow water layer at offsets beyond ~25 km. Ocean- bottom seismometers (OBSs), as opposed to a long surface streamer, must be used to acquire data suitable for crustal-scale vertical imaging. The critical distance for Moho reflections (PmP) in oceanic crust is also ~25 km, thus Pg-r and PmP-r are observed with very little separation, and the fault-reflected mantle refraction (Pn-r) arrives prior to Pg-r as the observation window opens with increased OBS-to-fault distance. This situation presents difficulties for "first-arrival" based Kirchoff migration approaches and suggests that wave- equation approaches, which in theory can image all three phases simultaneously, may be more suitable for vertical imaging in oceanic crust. We will present a comparison of these approaches as applied to a synthetic dataset generated from realistic, stochastic velocity models. We will assess their suitability, the migration artifacts unique to the deep ocean, and the ideal instrument layout for such an experiment.

Estuarine retention of larvae of the crab Rhithropanopeus harrisii

NASA Astrophysics Data System (ADS)

Cronin, Thomas W.

1982-08-01

Larvae of estuarine organisms continually face possible export from the parent estuary. Retention of larvae of the estuarine crab Rhithropanopeus harrisii was investigated in the upper Newport River estuary, North Carolina. All of the developmental stages occurred in the same area of the estuary with similar horizontal distributions, and the concentrations of intermediate and late stages were not greatly reduced from those of the first larval stage. This was strong evidence for the continuous retention of larvae in the upper estuary. To determine mechanisms by which retention might be effected, field studies of the vertical distributions and migrations of these larvae were made. The four zoeal stages had similar but complex vertical migration patterns, which varied from study to study. These migrations centered on the depth of no net flow, reducing longitudinal transport during development. Cross-spectral analysis of the larval migrations and the environmental cycles of light, salinity and current speed revealed that each of these external cycles affected larval depth. Megalopae of R. harrisii also migrated vertically, but they were present in much lower concentrations than the zoeal stages, an indication of a change to benthic existence in this final larval form.

Method of remediation of contaminants in porous media through minimization of bouyancy effects

DOEpatents

Shook, G. Michael; Pope, Gary A.

1999-01-01

A method for controlling vertical migration of contaminants in an aquifer includes introduction of a solubilizing solution having a surfactant and an alcohol or other light co-solvent. The surfactant is selected to solubilize the contaminant. The alcohol or other solvent is selected to provide the microemulsion with a substantially neutral buoyancy with respect to groundwater. The neutral buoyancy of the microemulsion prevents the normal downward movement which is typical of the solubilized dense non-aqueous phase liquid in surfactant-enhanced aquifer remediation. Thus, the risk that any significant amount of the solubilized dense non-aqueous contaminants will migrate vertically can be controlled. The relative tendency for vertical migration may also be reduced by increasing the injection rate or injected fluid viscosity (by adding polymer), or by reducing the well spacing.

Origin and migration of hydrocarbon gases and carbon dioxide, Bekes Basin, southeastern Hungary

USGS Publications Warehouse

Clayton, J.L.; Spencer, C.W.; Koncz, I.; Szalay, A.

1990-01-01

The Bekes Basin is a sub-basin within the Pannonian Basin, containing about 7000 m of post-Cretaceous sedimentary rocks. Natural gases are produced from reservoirs (Precambrian to Tertiary in age) located on structural highs around the margins of the basin. Gas composition and stable carbon isotopic data indicate that most of the flammable gases were derived from humic kerogen contained in source rocks located in the deep basin. The depth of gas generation and vertical migration distances were estimated using quantitative source rock maturity-carbon isotope relationships for methane compared to known Neogene source rock maturity-depth relationships in the basin. These calculations indicate that as much as 3500 m of vertical migration has occured in some cases. Isotopically heavy (> - 7 > 0) CO2 is the predominant species present in some shallow reservoirs located on basin-margin structural highs and has probably been derived via long-distance vertical and lateral migration from thermal decompositon of carbonate minerals in Mesozoic and older rocks in the deepest parts of the basin. A few shallow reservoirs (< 2000m) contain isotopically light (-50 to -60%0) methane with only minor amounts of C2+ homologs (< 3% v/v). This methane is probably mostly microbial in origin. Above-normal pressures, occuring at depths greater than 1800 m, are believed to be the principal driving force for lateral and vertical gas migration. These pressures are caused in part by active hydrocarbon generation, undercompaction, and thermal decomposition of carbonates. 

7 CFR 3431.9 - Eligibility to apply.

Code of Federal Regulations, 2011 CFR

2011-01-01

... applicant must: (1) Have a degree of Doctor of Veterinary Medicine (DVM), or the equivalent, from a college...; and (4) Provide certifications and verifications in accordance with § 3431.16. (b) Non-eligibility...

Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-9 Trench at the Hanford Site

NASA Astrophysics Data System (ADS)

Oostrom, M.; Rockhold, M.; Truex, M.; Thorne, P.; Last, G.; Rohay, V.

2006-12-01

Three-dimensional modeling was conducted with layered and heterogeneous models to enhance the conceptual model of CT distribution in the vertical and lateral direction beneath the 216-Z-9 trench and to investigate the effects of soil vapor extraction (SVE). This work supports the U.S. Department of Energy's (DOE's) efforts to characterize the nature and distribution of CT in the 200 West Area and subsequently select an appropriate final remedy. Simulations targeted migration of dense, nonaqueous phase liquid (DNAPL) consisting of CT and co-disposed organics in the subsurface beneath the 216-Z-9 trench as a function of the properties and distribution of subsurface sediments and of the properties and disposal history of the waste. Simulations of CT migration were conducted using the Subsurface Transport Over Multiple Phases (STOMP) simulator. Simulation results support a conceptual model for CT distribution where CT in the DNAPL phase is expected to have migrated primarily in a vertical direction below the disposal trench. Presence of small-scale heterogeneities tends to limit the extent of vertical migration of CT DNAPL due to enhanced retention of DNAPL compared to more homogeneous conditions, but migration is still predominantly in the vertical direction. Results also show that the Cold Creek units retain more CT DNAPL within the vadose zone than other hydrologic unit during SVE. A considerable amount of the disposed CT DNAPL may have partitioned to the vapor and subsequently water and sorbed phases. Presence of small-scale heterogeneities tends to increase the amount of volatilization. Any continued migration of CT from the vadose zone to the groundwater is likely through interaction of vapor phase CT with the groundwater and not through continued DNAPL migration. The results indicated that SVE appears to be an effective technology for vadose zone remediation, but additional effort is needed to improve simulation of the SVE process.

Theories on migration processes of Cd in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Li, Haixia; Wang, Qi; Ding, Jun; Zhang, Longlei

2018-03-01

Understanding the migration progress is essential to pollution control, while developing theories for the migration progress is the scientific basis. This paper further developed five key theories on migration processes of Cd including homogeneous theory, environmental dynamic theory, horizontal loss theory, migration trend theory and vertical migration theory, respectively. The performance and practical values of these theories were demonstrated in the application of these on analyzing the migration process of Cd in Jiaozhou Bay. Results these theory helpful to better understand the migration progress of pollutants in marine bay.

Know the Risks of Feeding Raw Food to Your Pets

MedlinePlus

... More sharing options Linkedin Pin it Email Print Dogs and cats aren’t exempt from the dangers ... food to contain organisms that can make your dog or cat sick, says William J. Burkholder, DVM, ...

Continuous flow measurements using fixed ultrasonic meters

USGS Publications Warehouse

Oltmann, Rick

1993-01-01

USGS has or soon will be installing four continuous flow-monitoring stations in the delta that will use ultrasonic velocity meters (DVM). Funding for the stations has been provided by USGS, DWR, USBR, and Contra Costa Water District.

Vertical ascending electrophoresis of cells with a minimal stabilizing medium

NASA Technical Reports Server (NTRS)

Omenyi, S. N.; Snyder, R. S.

1983-01-01

Vertical fractionation of a mixture of fixed horse and human red blood cells layered over a stabilizing support medium was done to give a valid comparison with proposed space experiments. In particular, the effects of sample thickness and concentration on zone migration rate were investigated. Electrophoretic mobilities of horse and human cells calculated from zone migration rates were compatible with those obtained by microelectrophoresis. Complete cell separation was observed when low power and effective cooling were employed.

Migration and diving behavior of Centrophorus squamosus in the NE Atlantic. Combining electronic tagging and Argo hydrography to infer deep ocean trajectories

NASA Astrophysics Data System (ADS)

Rodríguez-Cabello, Cristina; González-Pola, Cesar; Sánchez, Francisco

2016-09-01

A total of nine leafscale gulper sharks Centrophorus squamosus (Bonnaterre, 1788), were tagged with pop-up, satellite, archival, transmitting tags (PSAT) in the Marine Protected Area (MPA) of El Cachucho (Le Danois Bank) located in waters to the north of Spain, (NE Atlantic). Tags provided data on time, pressure and temperature that were used to examine movement patterns and diving behavior. Data collected from Argo floats in the study area have been used to devise a simple geolocation algorithm to infer the probable routes followed by this species. Tag release points revealed that C. squamosus moved both to the west (Galician waters) and to the north (Porcupine Bank) from the tagging area, suggesting well defined preferred pathways. The inferred trajectories indicated that sharks alternate periods constrained to specific geographical regions with quick and prompt movements covering large distances. Two sharks made conspicuous diurnal vertical migrations being at shallower depths around midnight and at maximum depths at midday, while other sharks did not make vertical migrations. Vertical movements were done smoothly and independently of the fish swimming long-distances or resting in the area. Overall results confirm that this species is highly migratory, supporting speeds of 20 nautical miles.day-1 and well capable to swim and make vertical migrations well above the abyssal plain.

Behavioral responses of Atlantic cod to sea temperature changes.

PubMed

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-05-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30-80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species.

Behavioral responses of Atlantic cod to sea temperature changes

PubMed Central

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-01-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30–80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species. PMID:26045957

Oxygen and Temperature Effects on Vertically Migrating Animals in Oxygen Minimum Zones

NASA Astrophysics Data System (ADS)

Seibel, B.

2016-02-01

Large populations of oceanic nekton and zooplankton undergo daily migrations from shallow water at night to depths greater than 200 m during the daytime. In some regions, these migrations cross extreme gradients of temperature, oxygen and carbon dioxide. Oxygen minimum zones (OMZs) are extensive and characterized by deep-water (100-800 m) oxygen partial pressures that would be lethal to most marine organisms, yet are tolerated by vertical migrators. Climate change is predicted to further deplete oxygen, and measurable reductions in oxygen have already been documented in some regions. Increases in shallow water temperature and carbon dioxide are occurring simultaneously. Oxygen levels and temperature are important drivers of biodiversity and distribution, and documented changes in community structure and function are reportedly associated with OMZ expansion and warming. Here I answer fundamental questions concerning zooplankton distributions, adaptations, and functions in oxygen minimum zones. In particular I report that metabolic suppression is a common strategy that facilitates diel occupancy of extreme hypoxia in many oceanic taxa. Anaerobic metabolic pathways play a minimal role in compensating for reduced aerobic ATP production. Numerous epigenetic mechanisms lead to reductions in energetically costly cellular processes, such as transcription and translation. Total metabolism is reduced by 50% or more during exposure to levels of hypoxia that characterize the daytime habitat for most vertically-migrating zooplankton. I further show that many migrators approach their upper thermal maximum in shallow water at night. Thus expanding OMZs and global warming may together compress the habitable depth range for many species.

Cross-shelf transport of pink shrimp larvae: Interactions of tidal currents, larval vertical migrations and internal tides

USGS Publications Warehouse

Criales, Maria M.; Browder, Joan A.; Mooers, C.N.K.; Robblee, M.B.; Cardenas, H.; Jackson, Thomas L.

2007-01-01

Transport and behavior of pink shrimp Farfantepenaeus duorarum larvae were investigated on the southwestern Florida (SWF) shelf of the Gulf of Mexico between the Dry Tortugas spawning grounds and Florida Bay nursery grounds. Stratified plankton samples and hydrographic data were collected at 2 h intervals at 3 stations located on a cross-shelf transect. At the Marquesas station, midway between Dry Tortugas and Florida Bay, internal tides were recognized by anomalously cool water, a shallow thermocline with strong density gradients, strong current shear, and a high concentration of pink shrimp larvae at the shallow thermocline. Low Richardson numbers occurred at the pycnocline depth, indicating vertical shear instability and possible turbulent transport from the lower to the upper layer where myses and postlarvae were concentrated. Analysis of vertically stratified plankton suggested that larvae perform vertical migrations and the specific behavior changes ontogenetically; protozoeae were found deeper than myses, and myses deeper than postlarvae. Relative concentrations of protozoea in the upper, middle and bottom layers were consistent with a diel vertical migration, whereas that of postlarvae and myses were consistent with the semidiurnal tides in phase with the flood tide. Postlarvae, the shallowest dwellers that migrate with a semidiurnal periodicity, experienced the largest net onshore flux and larval concentrations were highly correlated with the cross-shelf current. These results provide the first evidence of an onshore tidal transport (a type of selective tidal stream transport, STST), in decapod larvae migrating in continental shelf waters offshore, ca. 100 km from the coast and at a depth of 20 m, while approaching the coastal nursery grounds. Longer time series would be necessary to establish whether internal tides play any role in the larval onshore transport of this species and determine if the STST is the dominant onshore transport mechanism.

Generalized migration in frequency-wavenumber domain (MGF-K) in anisotropic media

NASA Astrophysics Data System (ADS)

Kostecki, Andrzej; Półchłopek, Anna

2013-06-01

In this paper, the background of MGF-K migration in dual domain (wavenumber-frequency K-F and space-time) in anisotropic media is presented. Algorithms for poststack (zero-offset) and prestack migration are based on downward extrapolation of acoustic wavefield by shift-phase with correction filter for lateral variability of medium's parameters. In anisotropic media, the vertical wavenumber was determined from full elastic wavefield equations for two dimensional (2D) tilted transverse isotropy (TTI) model. The method was tested on a synthetic wavefield for TTI anticlinal model (zero-offset section) and on strongly inhomogeneous vertical transverse isotropy (VTI) Marmousi model. In both cases, the proper imaging of assumed media was obtained.

Inventory and vertical migration of ¹³⁷Cs in Spanish mainland soils.

PubMed

Legarda, F; Romero, L M; Herranz, M; Barrera, M; Idoeta, R; Valiño, F; Olondo, C; Caro, A

2011-06-01

In this study the total activity of (137)Cs deposited per unit area over the Spanish peninsular territory was analysed using a 150 × 150 km(2) mesh grid, with samples taken from 29 points. The deposited activities ranged between 251 and 6074 Bq/m(2). A linear relationship was obtained between these values and the mean annual rainfall at each sampling point which allowed a map to be drawn, using GIS software, which shows the distribution of total deposited (137)Cs activity across the Spanish mainland. At twelve of these sampling points the vertical migration profile of (137)Cs was obtained. These profiles are separated into two groups with different behaviour, one of which includes clay and loam soils and the other containing sandy soils. For both groups of profiles the parameters of the convective-diffusive model, which describes the vertical migration of (137)Cs in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) were calculated. Copyright © 2011 Elsevier Ltd. All rights reserved.

Geographic differences in vertical connectivity in the Caribbean coral Montastraea cavernosa despite high levels of horizontal connectivity at shallow depths.

PubMed

Serrano, X; Baums, I B; O'Reilly, K; Smith, T B; Jones, R J; Shearer, T L; Nunes, F L D; Baker, A C

2014-09-01

The deep reef refugia hypothesis proposes that deep reefs can act as local recruitment sources for shallow reefs following disturbance. To test this hypothesis, nine polymorphic DNA microsatellite loci were developed and used to assess vertical connectivity in 583 coral colonies of the Caribbean depth-generalist coral Montastraea cavernosa. Samples were collected from three depth zones (≤10, 15-20 and ≥25 m) at sites in Florida (within the Upper Keys, Lower Keys and Dry Tortugas), Bermuda, and the U.S. Virgin Islands. Migration rates were estimated to determine the probability of coral larval migration from shallow to deep and from deep to shallow. Finally, algal symbiont (Symbiodinium spp.) diversity and distribution were assessed in a subset of corals to test whether symbiont depth zonation might indicate limited vertical connectivity. Overall, analyses revealed significant genetic differentiation by depth in Florida, but not in Bermuda or the U.S. Virgin Islands, despite high levels of horizontal connectivity between these geographic locations at shallow depths. Within Florida, greater vertical connectivity was observed in the Dry Tortugas compared to the Lower or Upper Keys. However, at all sites, and regardless of the extent of vertical connectivity, migration occurred asymmetrically, with greater likelihood of migration from shallow to intermediate/deep habitats. Finally, most colonies hosted a single Symbiodinium type (C3), ruling out symbiont depth zonation of the dominant symbiont type as a structuring factor. Together, these findings suggest that the potential for shallow reefs to recover from deep-water refugia in M. cavernosa is location-specific, varying among and within geographic locations likely as a consequence of local hydrology. © 2014 John Wiley & Sons Ltd.

Diel changes in the near-surface biomass of zooplankton and the carbon content of vertical migrants

NASA Astrophysics Data System (ADS)

Hays, Graeme C.; Harris, Roger P.; Head, Robert N.

Zooplankton biomass and the carbon content of vertical migrants were measured in the NE Atlantic (36.5°N, 19.2°W) between 11 and 18 July 1996 as part of the Plankton Reactivity in the Marine Environment (PRIME) programme. The increase in zooplankton biomass near the surface (0-100 m) at night compared to during the day suggested that diel vertical migration was an important feature at this site. For three species of vertically migrant copepods, Pleuromamma pisekii, P. gracilis and P. abdominalis, the carbon content of individuals collected at dusk was significantly less than for individuals collected at dawn, with this reduction being 6.2, 7.3 and 14.8%, respectively. This dawn-dusk reduction in carbon content is consistent with the diel pattern of feeding and fasting exhibited by vertical migrants and supports the suggestion that migrating zooplankton will cause an active export of carbon from the surface layers.

Astronaut David Wolf draws blood from Martin Fettman for SLS-2 investigations

NASA Technical Reports Server (NTRS)

1993-01-01

Inside the science module aboard the Earth-orbiting Space Shuttle Columbia, Astronaut David A. Wolf draws blood from payload specialists Martin J. Fettman, DVM. Blood samples from crew members are critical to several Spacelab Life Sciences (SLS-2) investigations.

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

NASA Astrophysics Data System (ADS)

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 and V descended continuously. Zoeae III had behaviors that were intermediate to those of the earlier- and later-stage zoeae. Postlarvae underwent a normal diel migration (nocturnal ascent) regardless of tides, with the deepest position (below 60 m and/or on the bottom) during the day. These findings give a new perspective towards how complex vertical migration patterns in meroplanktonic larvae enable their retention in inner shelf waters before the final entry of postlarvae into their natal populations.

Imaging tilted transversely isotropic media with a generalised screen propagator

NASA Astrophysics Data System (ADS)

Shin, Sung-Il; Byun, Joongmoo; Seol, Soon Jee

2015-01-01

One-way wave equation migration is computationally efficient compared with reverse time migration, and it provides a better subsurface image than ray-based migration algorithms when imaging complex structures. Among many one-way wave-based migration algorithms, we adopted the generalised screen propagator (GSP) to build the migration algorithm. When the wavefield propagates through the large velocity variation in lateral or steeply dipping structures, GSP increases the accuracy of the wavefield in wide angle by adopting higher-order terms induced from expansion of the vertical slowness in Taylor series with each perturbation term. To apply the migration algorithm to a more realistic geological structure, we considered tilted transversely isotropic (TTI) media. The new GSP, which contains the tilting angle as a symmetric axis of the anisotropic media, was derived by modifying the GSP designed for vertical transversely isotropic (VTI) media. To verify the developed TTI-GSP, we analysed the accuracy of wave propagation, especially for the new perturbation parameters and the tilting angle; the results clearly showed that the perturbation term of the tilting angle in TTI media has considerable effects on proper propagation. In addition, through numerical tests, we demonstrated that the developed TTI-GS migration algorithm could successfully image a steeply dipping salt flank with high velocity variation around anisotropic layers.

Control of Subsurface Contaminant Migration by Vertical Engineered Barriers

EPA Science Inventory

This Fact Sheet is intended to provide remedial project managers (RPMs), on-scene coordinators (OSCs), contractors, and other remediation stakeholders with a basic overview of hazardous waste containment systems constructed to prevent or limit the migration of contamination in gr...

A flexible approach to training veterinarians in public health: an overview and early assessment of the DVM/MPH dual-degree program at the University of Minnesota.

PubMed

Minicucci, Larissa A; Hanson, Kate A; Olson, Debra K; Hueston, William D

2008-01-01

As a result of the growing need for public-health veterinarians, novel educational programs are essential to train future public-health professionals. The University of Minnesota School of Public Health, in collaboration with the College of Veterinary Medicine, initiated a dual DVM/MPH program in 2002. This program provides flexibility by combining distance learning and on-campus courses offered through a summer public-health institute. MPH requirements are completed through core courses, elective courses in a focus area, and an MPH project and field experience. Currently, more than 100 students representing 13 veterinary schools are enrolled in the program. The majority of initial program graduates have pursued public-practice careers upon completion of the program. Strengths of the Minnesota program design include accessibility and an environment to support multidisciplinary training. Continued assessment of program graduates will allow for evaluation and adjustment of the program in the coming years.

Large eddy simulation of spanwise rotating turbulent channel flow with dynamic variants of eddy viscosity model

NASA Astrophysics Data System (ADS)

Jiang, Zhou; Xia, Zhenhua; Shi, Yipeng; Chen, Shiyi

2018-04-01

A fully developed spanwise rotating turbulent channel flow has been numerically investigated utilizing large-eddy simulation. Our focus is to assess the performances of the dynamic variants of eddy viscosity models, including dynamic Vreman's model (DVM), dynamic wall adapting local eddy viscosity (DWALE) model, dynamic σ (Dσ ) model, and the dynamic volumetric strain-stretching (DVSS) model, in this canonical flow. The results with dynamic Smagorinsky model (DSM) and direct numerical simulations (DNS) are used as references. Our results show that the DVM has a wrong asymptotic behavior in the near wall region, while the other three models can correctly predict it. In the high rotation case, the DWALE can get reliable mean velocity profile, but the turbulence intensities in the wall-normal and spanwise directions show clear deviations from DNS data. DVSS exhibits poor predictions on both the mean velocity profile and turbulence intensities. In all three cases, Dσ performs the best.

Effects of particle migration on the features of their transport by tidal currents in a region of freshwater influence

NASA Astrophysics Data System (ADS)

Korotenko, K. A.; Sentchev, A. V.

2008-10-01

Using a combined model that couples a three-dimensional ocean circulation model, a model for tidal currents, and a model for particle transport, the structure of the velocity field of the tidal current and the transport of particles migrating over the vertical were studied in the zone of the influence of the riverine runoff in the eastern part of the English Channel. It was found that the interaction between the tidal current and the baroclinic flow formed by the riverine runoff off the northeastern coast of France generates a steady-state intensive (˜0.3 m/s) residual current in the zone of the effect of the riverine runoff. In order to assess the influence of different types of particle migration (which simulate ichthyoplankton) on the processes of their transport in the region under consideration, we performed numerical experiments with particle clusters, for which parameterization of their migration was implemented on the basis of the field observations over the proper vertical movements of different types of ichthyoplankton. The experiments showed that the distribution of the fields of the particle concentrations and the velocities of their movements depend not only on the background hydrophysical conditions but also on the character of the vertical migration of the particles. In this paper, a comparison between the results of the modeling and those of the field observations in the region under consideration are presented.

Validating proposed migration equation and parameters' values as a tool to reproduce and predict 137Cs vertical migration activity in Spanish soils.

PubMed

Olondo, C; Legarda, F; Herranz, M; Idoeta, R

2017-04-01

This paper shows the procedure performed to validate the migration equation and the migration parameters' values presented in a previous paper (Legarda et al., 2011) regarding the migration of 137 Cs in Spanish mainland soils. In this paper, this model validation has been carried out checking experimentally obtained activity concentration values against those predicted by the model. This experimental data come from the measured vertical activity profiles of 8 new sampling points which are located in northern Spain. Before testing predicted values of the model, the uncertainty of those values has been assessed with the appropriate uncertainty analysis. Once establishing the uncertainty of the model, both activity concentration values, experimental versus model predicted ones, have been compared. Model validation has been performed analyzing its accuracy, studying it as a whole and also at different depth intervals. As a result, this model has been validated as a tool to predict 137 Cs behaviour in a Mediterranean environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Do predators influence the distribution of age-0 kokanee in a Colorado Reservoir?

USGS Publications Warehouse

Hardiman, J.M.; Johnson, B.M.; Martinez, P.J.

2004-01-01

Seasonal changes in reservoir conditions such as productivity, light, and temperature create spatiotemporal variation in habitat that may segregate or aggregate predators and prey, producing implications for the distribution, growth, and survival of fishes. We used hydroacoustics to document the diel vertical distribution of age-0 kokanee Oncorhynchus nerka relative to environmental gradients at Blue Mesa Reservoir, Colorado, during May-August of 2002. Temperature, light, and zooplankton density profiles were examined relative to foraging conditions for kokanee and their primary predator, lake trout Salvelinus namaycush. Age-0 kokanee displayed large diel vertical migrations in May despite the lack of an energetic advantage before reservoir stratification. Age-0 kokanee minimized near-surface foraging at this time, perhaps to avoid predation by visual predators, such as lake trout, in the well-lit surface waters. Strong reservoir stratification in midsummer appeared to provide a thermal refuge from lake trout that the kokanee exploited. By August vertical migrations were shallow and most kokanee remained in the epilimnion throughout the day. Although the energetic implications of the late-summer strategy are unclear, it appears that kokanee were responding to changes in their predator environment. A robust model for kokanee diel vertical migration across a range of systems should include a predator avoidance component.

Migration of the Cratering Flow-Field Center with Implications for Scaling Oblique Impacts

NASA Technical Reports Server (NTRS)

Anderson, J. L. B.; Schultz, P. H.; Heineck, J. T.

2004-01-01

Crater-scaling relationships are used to predict many cratering phenomena such as final crater diameter and ejection speeds. Such nondimensional relationships are commonly determined from experimental impact and explosion data. Almost without exception, these crater-scaling relationships have used data from vertical impacts (90 deg. to the horizontal). The majority of impact craters, however, form by impacts at angles near 45 deg. to the horizontal. While even low impact angles result in relatively circular craters in sand targets, the effects of impact angle have been shown to extend well into the excavation stage of crater growth. Thus, the scaling of oblique impacts needs to be investigated more thoroughly in order to quantify fully how impact angle affects ejection speed and angle. In this study, ejection parameters from vertical (90 deg.) and 30 deg. oblique impacts are measured using three-dimensional particle image velocimetry (3D PIV) at the NASA Ames Vertical Gun Range (AVGR). The primary goal is to determine the horizontal migration of the cratering flow-field center (FFC). The location of the FFC at the time of ejection controls the scaling of oblique impacts. For vertical impacts the FFC coincides with the impact point (IP) and the crater center (CC). Oblique impacts reflect a more complex, horizontally migrating flow-field. A single, stationary point-source model cannot be used accurately to describe the evolution of the ejection angles from oblique impacts. The ejection speeds for oblique impacts also do not follow standard scaling relationships. The migration of the FFC needs to be understood and incorporated into any revised scaling relationships.

Vertical patterns of ichthyoplankton at the interface between a temperate estuary and adjacent coastal waters: Seasonal relation to diel and tidal cycles

NASA Astrophysics Data System (ADS)

Primo, Ana Lígia; Azeiteiro, Ulisses M.; Marques, Sónia C.; Ré, Pedro; Pardal, Miguel A.

2012-07-01

Vertical distribution and migration pattern of ichthyoplankton assemblage in the Mondego estuary were investigated in relation to diel and tidal cycle. Summer and winter communities were sampled, at surface and bottom, over a diel cycle during spring and neap tides at a fixed station at the mouth of the estuary. Summer presented higher larvae density mainly of Pomatoschistus spp., Gobius niger and Parablennius pilicornis. Main species in winter assemblages were Pomatoschistus spp. and Sardina pilchardus. There were no differences between depth stratums across diel or tide cycle. Nevertheless, main species larval densities showed significant periodic variation associated with tide (M2) and diel (K1) cycles presenting generally, higher density at night and around low tide. Conversely, vertical patterns observed could not be related with diel or tidal cycle. Tough, main species presented some extent of vertical migration. Vertical patterns observed appear to be related to seasonal stratification and river flow, increasing amplitude during periods of less stratification and lower water currents. Present study provides a better understanding of ichthyoplankton vertical movement patterns and of small scale dynamics at the interface of two coastal European systems.

78 FR 13363 - Center for Scientific Review; Notice of Closed Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

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... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Center for Scientific Review... personal privacy. Name of Committee: Center for Scientific Review Special Emphasis Panel; Small Business...). Contact Person: Bukhtiar H Shah, DVM, Ph.D., Scientific Review Officer, Center for Scientific Review...

INTERPRETING SPONTANEOUS RENAL LESIONS IN SAFETY AND RISK ASSESSMENT

EPA Science Inventory

Interpreting Spontaneous Renal Lesions in Safety and Risk Assessment
Douglas C. Wolf, D.V.M., Ph.D.

Introduction

Risk assessment is a process whereby the potential adverse health effects from exposure to a xenobiotic are predicted after evaluation of the availab...

A laboratory animal science pioneer.

PubMed

Kostomitsopoulos, Nikolaos

2014-11-01

Nikolaos Kostomitsopoulos, DVM, PhD, is Head of Laboratory Animal Facilities and Designated Veterinarian, Center of Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece. Dr. Kostomitsopoulos discusses his successes in implementing laboratory animal science legislation and fostering collaboration among scientists in Greece.

INFLUENCE OF STRATIGRAPHY ON A DIVING MTBE PLUME AND ITS CHARACTERIZATION: A CASE STUDY

EPA Science Inventory

Conventional conceptual models applied at petroleum release sites are often based on assumptions of vertical contaminant migration through the vadose zone followed by horizontal, downgradient transport at the water table with limited, if any, additional downward migration. Howev...

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 2

EPA Science Inventory

As contaminant ground water flows downgradient from a release point, its movement is dictated by site geological conditions and hydraulics that may result in significant perpendicular contamination migration. This vertical migration pattern has been termed 'plume diving'. Under ...

The Application of Depth Migration for Processing GPR Data

NASA Astrophysics Data System (ADS)

Hoai Trung, Dang; Van Giang, Nguyen; Thanh Van, Nguyen

2018-03-01

Migration methods play a significant role in processing ground penetrating radar data. Beside recovering the true image of subsurface structures from the prior designed velocity model and the raw GPR data, the migration algorithm could be an effective tool in bulding real environmental velocity model. In this paper, we have proposed one technique using energy diagram extracted from migrated data as a criterion of looking for the correct velocity. Split Step Fourier migration, a depth migration, is chosen for facing the challenge where the velocity varies laterally and vertically. Some results verified on field data on Vietnam show that migrated sections with calculated velocity from energy diagram have the best quality.

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Dynamic modelling of future land use change under urbanization and climate change pressures: application to a case study in central Belgium

NASA Astrophysics Data System (ADS)

Jacquemin, I.; Fontaine, C. M.; Dendoncker, N.; François, L.; De Vreese, R.; Marek, A.; Mortelmans, D.; Van Herzele, A.; Devillet, G.

2012-04-01

Projecting the future of the evolution of socio-ecological systems to analyse their sustainability under climate or other environmental changes is not straightforward. Current projections usually use process-oriented models describing the complex interactions within the physical/biological systems (ecosystems), while the socio-economic constraints are represented with the help of scenarios. However, the actual evolution can be expected to be much more complex, because of the mutual interactions between ecological and socio-economic systems. To represent these interactions, models must integrate the complex process of human decision at individual or society levels. Moreover, models must be spatially explicit, defining elementary spatial units on which can act both the physical factors and the human decision process. These spatial units (e.g., farm fields) must be described not only in terms of energy, water, carbon and nutrient flows, but also in terms of the flow of ecosystem goods and services (EGS) they provide to the society together with the management costs required to sustain them. The provision of EGS may be altered in the future in response to changes in the climate system and the environment, but also through various human pressures on the landscape such as urbanization, as well as through the reaction of human societies to these changes in EGS provision. In the VOTES ("Valuation Of Terrestrial Ecosystem Services in a multifunctional peri-urban space") project, we attempt to model this coupled socio-ecological system by combining a dynamic vegetation model (DVM) with an agent-based model (ABM). The DVM (CARAIB; Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) model describes the evolution of physical and biological processes in the ecosystems, i.e. the impact of climate change and land management on the energy, water and carbon budgets, as well as the productivity of each simulated plant species present on each land unit. The original version of the model developed for natural vegetation has been upgraded to include crop systems and pastures. The ABM (Murray-Rust, Journal of Land Use Science, 6(2-3):83-99, 2011) describes the management choices (e.g., crop rotation, intensive agriculture or organic farming, etc) for each land plot, as well as the possible change in their affectation (e.g., conversion of farm fields to residential areas in response to urbanization), under different socio-economic contexts described in the storyline of three scenarios depicting general societal orientations (business-as-usual; market oriented; sustainability oriented). As a result, the ABM produces a dynamic evolution of land use and management options to be passed on to the DVM for further analysis. The outputs from the DVM allow evaluating quantitatively the provision of EGS by each land plot. This DVM-ABM modelling tool is thus able to describe the future evolution of land use and land cover, as well as of EGS production, in the context of socio-economic scenarios. The model is applied to a case study area covering four municipalities located in central Belgium close to Brussels and Leuven. The area is mostly composed of agricultural fields (crops and meadows), residential areas and a large protected forest (Meerdaalbos) and is subject to intense urbanization pressure due to the proximity to Brussels.

Seismic patterns and migration history of submarine fan channels in deep-water area, Niger Delta, West Africa

NASA Astrophysics Data System (ADS)

Zhang, Guotao; Zhang, Shangfeng; Li, Yuan

2015-04-01

The channels of deep-water submarine fan under Niger delta slope are characterized by large dimensions special deposition positions and complex formation processes, its geographical location and sedimentary environment also hinder the research and exploration development. According to the strata slicing, RMS amplitude attribute and other techniques, we exhibit the platforms patterns of channels at different period, and based on the analysis of internal architecture and deformation history of channel-leveed systems, migration and evolution process of channel systems could be understood accurately. A great quantity of isolated channels develop in middle Miocene and aggrading streams in late Miocene, which generating because of large scale of turbidity caused by the drop of second order sea-level, which characterized by vertical accretion at smooth channel, while vertical accretion and lateral migration at bend. Evolution of channel systems can be divided into three stages: the initial erosion, erosion and filling alternately, and abandoned stage. With these three stages, the sinuosity of channel change from moderate to high, then decrease. Incision and filling of channels, being during the three development phases, is the driving force of meander-loops migration, which promote three kinds of migration patterns: lateral, down-system and combination migration. The research provides theoretical basis for high-precision prediction and evaluation of deep-water reservoir.

Wrenching and oil migration, Mervine field, Kay County, Oklahoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, H.G.

1985-02-01

Since 1913, Mervine field (T27N, R3E) has produced oil from 11 Mississippian and Pennsylvanian zones, and gas from 2 Permian zones. The field exhibits an impressive asymmetric surface anticline, with the steeper flank dipping 30/sup 0/E maximum. A nearly vertical, basement-involved fault develops immediately beneath the steeper flank of the surface anticline. Three periods of left-lateral wrench faulting account for 93% of all structural growth: 24% in post-Mississippian-pre-Desmoinesian time, 21% in Virgilian time, and 48% in post-Wolfcampian time. In Mesozoic through early Cenozoic times, the Devonian Woodford Shale (and possibly the Desmoinesian Cherokee shales) locally generated oil, which should havemore » been structurally trapped in the Ordovician Bromide sandstone. This oil may have joined oil already trapped in the Bromide, which had migrated to the Mervine area in the Early Pennsylvanian from a distant source. Intense post-Wolfcampian movement(s) fractured the competent pre-Pennsylvanian rocks, allowing Bromide brine and entrained oil to migrate vertically up the master fault, finally accumulating in younger reservoirs. Pressure, temperature, and salinity anomalies attest to vertical fluid migration continuing at the present time at Mervine field. Consequently, pressure, temperature, and salinity mapping should be considered as valuable supplements to structural and lithologic mapping when prospecting for structural hydrocarbon accumulations in epicratonic provinces.« less

Application of an automatic approach to calibrate the NEMURO nutrient-phytoplankton-zooplankton food web model in the Oyashio region

NASA Astrophysics Data System (ADS)

Ito, Shin-ichi; Yoshie, Naoki; Okunishi, Takeshi; Ono, Tsuneo; Okazaki, Yuji; Kuwata, Akira; Hashioka, Taketo; Rose, Kenneth A.; Megrey, Bernard A.; Kishi, Michio J.; Nakamachi, Miwa; Shimizu, Yugo; Kakehi, Shigeho; Saito, Hiroaki; Takahashi, Kazutaka; Tadokoro, Kazuaki; Kusaka, Akira; Kasai, Hiromi

2010-10-01

The Oyashio region in the western North Pacific supports high biological productivity and has been well monitored. We applied the NEMURO (North Pacific Ecosystem Model for Understanding Regional Oceanography) model to simulate the nutrients, phytoplankton, and zooplankton dynamics. Determination of parameters values is very important, yet ad hoc calibration methods are often used. We used the automatic calibration software PEST (model-independent Parameter ESTimation), which has been used previously with NEMURO but in a system without ontogenetic vertical migration of the large zooplankton functional group. Determining the performance of PEST with vertical migration, and obtaining a set of realistic parameter values for the Oyashio, will likely be useful in future applications of NEMURO. Five identical twin simulation experiments were performed with the one-box version of NEMURO. The experiments differed in whether monthly snapshot or averaged state variables were used, in whether state variables were model functional groups or were aggregated (total phytoplankton, small plus large zooplankton), and in whether vertical migration of large zooplankton was included or not. We then applied NEMURO to monthly climatological field data covering 1 year for the Oyashio, and compared model fits and parameter values between PEST-determined estimates and values used in previous applications to the Oyashio region that relied on ad hoc calibration. We substituted the PEST and ad hoc calibrated parameter values into a 3-D version of NEMURO for the western North Pacific, and compared the two sets of spatial maps of chlorophyll- a with satellite-derived data. The identical twin experiments demonstrated that PEST could recover the known model parameter values when vertical migration was included, and that over-fitting can occur as a result of slight differences in the values of the state variables. PEST recovered known parameter values when using monthly snapshots of aggregated state variables, but estimated a different set of parameters with monthly averaged values. Both sets of parameters resulted in good fits of the model to the simulated data. Disaggregating the variables provided to PEST into functional groups did not solve the over-fitting problem, and including vertical migration seemed to amplify the problem. When we used the climatological field data, simulated values with PEST-estimated parameters were closer to these field data than with the previously determined ad hoc set of parameter values. When these same PEST and ad hoc sets of parameter values were substituted into 3-D-NEMURO (without vertical migration), the PEST-estimated parameter values generated spatial maps that were similar to the satellite data for the Kuroshio Extension during January and March and for the subarctic ocean from May to November. With non-linear problems, such as vertical migration, PEST should be used with caution because parameter estimates can be sensitive to how the data are prepared and to the values used for the searching parameters of PEST. We recommend the usage of PEST, or other parameter optimization methods, to generate first-order parameter estimates for simulating specific systems and for insertion into 2-D and 3-D models. The parameter estimates that are generated are useful, and the inconsistencies between simulated values and the available field data provide valuable information on model behavior and the dynamics of the ecosystem.

Spatial distribution and vertical migrations of fish larvae communities off Northwestern Iberia sampled with LHPR and Bongo nets

NASA Astrophysics Data System (ADS)

Garrido, Susana; Santos, A. Miguel P.; dos Santos, Antonina; Ré, Pedro

2009-10-01

The spatial distribution and diel vertical migration of fish larvae were studied in relation to the environmental conditions off NW Iberia during May 2002. Larvae from 23 families were identified, the most abundant were the Clupeidae, Gobiidae, Callionymidae, Blenniidae, Sparidae and Labridae. Sardina pilchardus was the most abundant species, mean concentrations 1 order of magnitude higher than the other fish larvae species. Larval horizontal distribution was mainly related to upwelling-driven circulation, resulting in an offshore increase of larval abundance while the vertical distribution was closely associated to the Western Iberia Buoyant Plume. Despite this general trend, taxon-specific relationships between the distribution of larvae and environmental variables were observed, and temperature was an important regressor explaining the distribution of most taxa. A comparison between ichthyoplankton samples collected alternatively with the LHPR and Bongo nets resulted in captures of larvae ≈1 order of magnitude higher for the LHPR, probably related to its higher towing speed. The spatial distribution and relative composition of larvae were also different for both nets, although the most frequent/abundant groups were the same. A fixed station sampled for 69-h showed diel vertical migrations performed by the larvae, with the highest larval concentrations occurring at surface layers during the night and most larvae being found in the neuston layer only during that period.

Light and lunar cycle as cues to diel migration of a sound-scattering layer

NASA Astrophysics Data System (ADS)

Benoit-Bird, Kelly J.; Au, Whitlow W. L.

2001-05-01

The Hawaiian mesopelagic boundary community is an island-associated midwater scattering layer comprised of small fishes, shrimps, and squids that undergoes diel vertical as well as horizontal migrations. It has been hypothesized that light levels are an important cue or trigger for vertical migration and presumably, horizontal migration. The migration pattern of the scattering layer was measured over complete lunar cycles while the incident light levels were recorded. Due to differences in the rise and set times of the moon and cloud cover, light and lunar cycle were not completely coupled, allowing separation of the light effects of moon phase and other cues associated with lunar cycle. Four calibrated echosounder moorings were deployed with approximately even spacing, perpendicular to the leeward coast of Oahu. Moorings were deployed for one complete lunar cycle at each of three locations, recording 10 echoes every 15 min. Light sensors measured the nocturnal light intensity at 30-s intervals. Statistical analysis revealed significant effects of both light and other lunar cycle cues. Overall, the effect size was very low considering the light transmission characteristics of the subtropical Pacific, making measurement from stationary acoustic platforms critical.

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining.

PubMed

Zhang, Xu; Yang, Huanhuan; Cui, Zhaojie

2017-10-01

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.

Heavy metal migration in soils and rocks at historical smelting sites.

PubMed

Maskall, J; Whitehead, K; Thornton, I

1995-09-01

The vertical migration of metals through soils and rocks was investigated at five historical lead smelting sites ranging in age between 220 and 1900 years. Core samples were taken through metal-contaminated soils and the underlying strata. Concentration profiles of lead and zinc are presented from which values for the distances and rates of migration have been derived. Slag-rich soil horizons contain highly elevated metal concentrations and some contamination of underlying strata has occurred at all sites. However, the amounts of lead and zinc that have migrated from soils and been retained at greater depths are comparatively low. This low metal mobility in contaminated soils is partly attributed to the elevation of soil pH by the presence of calcium and carbonate originating from slag wastes and perhaps gangue minerals. Distances and rates of vertical migration were higher at those sites with soils underlain by sandstone than at those with soils underlain by clay. For sites with the same parent material, metal mobility appears to be increased at lower soil pH. The mean migration rates for lead and zinc reach maxima of 0.75 and 0.46 cm yr(-1) respectively in sandstone at Bole A where the elements have moved mean distances of 4.3 and 2.6 m respectively. There is some evidence that metal transport in the sandstone underlying Bole A and Cupola B occurs preferentially along rock fractures. The migration of lead and zinc is attenuated by subsurface clays leading to relatively low mean migration rates which range from 0.03 to 0.31 cm yr(-1) with many values typical of migration solely by diffusion. However, enhanced metal migration in clays at Cupola A suggest a preferential transport mechanism possibly in cracks or biopores.

Phosphorus vertical migration in aquic brown soil and light chernozem under different phosphorous application rate: a soil column leaching experiment.

PubMed

Zhao, Muqiu; Chen, Xin; Shi, Yi; Zhou, Quanlai; Lu, Caiyan

2009-01-01

A soil column leaching experiment was conducted to study the vertical migration of phosphorus in aquic brown soil and light chernozem under different phosphorus fertilization rates. The results showed that total dissolved phosphorus concentration in the leachates from the two soils was nearly the same, but dissolved inorganic phosphorus concentration was obviously different. In all fertilization treatments, aquic brown soil had a higher content of phosphorus in calcium chloride extracts compared with light chernozem. But Olsen phosphorus content was higher at the soil depth beneath 0-20 cm, and increased with increasing phosphorus application rate.

Inventory and vertical migration of 90Sr fallout and 137Cs/90Sr ratio in Spanish mainland soils.

PubMed

Herranz, M; Romero, L M; Idoeta, R; Olondo, C; Valiño, F; Legarda, F

2011-11-01

In this paper the inventory of (90)Sr in 34 points distributed along the Spanish peninsular territory is presented. Obtained values range between 173 Bq/m(2) and 2047 Bq/m(2). From these data set and those (137)Cs data obtained in a previous work the (137)Cs/(90)Sr activity ratio has been established, laying this value between 0.9 and 3.6. Also the migration depth of both radionuclides has been analysed obtaining for (137)Cs an average value 57% lower than that obtained for (90)Sr. Additionally, this paper presents the results obtained in 11 sampling points in which the activity vertical profile has been measured. These profiles have been analysed to state the behaviour of strontium in soils and after, by using a convective-diffusive model, the parameters of the model which governs the vertical migration of (90)Sr in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) have been evaluated. Mean values obtained are 0.20 cm/year and 3.67 cm(2)/year, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

Asad Umar, DVM, PhD | Division of Cancer Prevention

Cancer.gov

The Division of Cancer Prevention (DCP) conducts and supports research to determine a person's risk of cancer and to find ways to reduce the risk. This knowledge is critical to making progress against cancer because risk varies over the lifespan as genetic and epigenetic changes can transform healthy tissue into invasive cancer.

Asad Umar, DVM, PhD | Division of Cancer Prevention

Cancer.gov

Dr. Asad Umar received his PhD in Biochemistry and Immunology at the Johns Hopkins University in Baltimore, MD, in 1993. He conducted his postdoctoral training in the laboratories of Patricia Gearhart in Baltimore, MD and Thomas Kunkel at the National Institutes of Environmental Health Sciences in Research Triangle Park, NC. Dr. |

Blocking and guiding adult sea lamprey with pulsed direct current from vertical electrodes

USGS Publications Warehouse

Johnson, Nicholas S.; Thompson, Henry T.; Holbrook, Christopher M.; Tix, John A.

2014-01-01

Controlling the invasion front of aquatic nuisance species is of high importance to resource managers. We tested the hypothesis that adult sea lamprey (Petromyzon marinus), a destructive invasive species in the Laurentian Great Lakes, would exhibit behavioral avoidance to dual-frequency pulsed direct current generated by vertical electrodes and that the electric field would not injure or kill sea lamprey or non-target fish. Laboratory and in-stream experiments demonstrated that the electric field blocked sea lamprey migration and directed sea lamprey into traps. Rainbow trout (Oncorhynchus mykiss) and white sucker (Catostomus commersoni), species that migrate sympatrically with sea lamprey, avoided the electric field and had minimal injuries when subjected to it. Vertical electrodes are advantageous for fish guidance because (1) the electric field produced varies minimally with depth, (2) the electric field is not grounded, reducing power consumption to where portable and remote deployments powered by solar, wind, hydro, or a small generator are feasible, and (3) vertical electrodes can be quickly deployed without significant stream modification allowing rapid responses to new invasions. Similar dual-frequency pulsed direct current fields produced from vertical electrodes may be advantageous for blocking or trapping other invasive fish or for guiding valued fish around dams.

Vertical distribution of Eucalanoid copepods within the Costa Rica Dome area of the Eastern Tropical Pacific

PubMed Central

Jackson, Melanie L.; Smith, Sharon L.

2016-01-01

A variety of ecological strategies for tolerance of low-oxygen conditions within the Costa Rica Dome (CRD) area of the Eastern Tropical Pacific are documented for the copepod family Eucalanidae. During the summer of 2010, we compared the ecological strategies used by the Eucalanidae inside and outside the central CRD region. We compared the vertical and horizontal distributions of five species, Eucalanus inermis, Subeucalanus subtenuis, Subeucalanus subcrassus, Subeucalanus pileatus and Pareucalanus attenuatus together with Rhincalanus species, in the epipelagic (upper 200 m) among four locations, which we grouped into a section roughly crossing the core CRD area (inside–outside core CRD). The coastal area outside the CRD supported the most diverse assemblage, whereas overall abundance of Eucalanidae in the central CRD was 2-fold greater than outside and dominated by E. inermis (>60%). Eucalanidae in the central CRD had a shallow depth distribution, closely associated with the shallow thermocline (10–20 m). There was no evidence of daily vertical migration in the central CRD, but E. inermis demonstrated vertical migration outside the CRD. The vertical abundance patterns of Eucalanidae in the CRD region reflect complex interactions between subtle physical–chemical differences and food resources. PMID:27275032

A model for migration and accumulation of hydrocarbons in the Thamama and Arab reservoirs in Abu Dhabi, U.A.E.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawas, M.F.; Takezaki, H.

1995-08-01

The distribution of hydrocarbons in the Lower Cretaceous Thamama Group and Upper Jurassic Arab Formation in Abu Dhabi is influenced by the development of the intervening Hith anhydrites. The geochemical analysis of Thamama and Arab hydrocarbons indicate that they were generated from a common source rock: the Upper Jurassic Diyab Formation. Studies carried out on the Miocene sabkha anhydrites in the coastal flat west of Abu Dhabi supported a model for vertical migration through the Hith anhydrites under certain conditions. The established model implies that the Diyab oil and gas had migrated essentially vertically and individually which means that themore » oil migrated prior to the gas and their distribution is controlled by the differential sealing potential of the anhydrites at each migration phase: a Hith anhydrite bed of more than 30 feet (ft.) thick was a perfect seal for hydrocarbon migration into the Arab reservoirs. In this case, oils could not break through to the overlying Thamama group. But where the anhydride bed thicknesses dropped below 30 ft. thick, this permitted oil migration through to the overlying Thamama reservoirs during the oil generation phase in the Turonian time. At a later stage, with additional depth of burial and progressive diagenesis anhydrite beds as thin as 8 ft. thick became effective seals. These controlled the distribution of the gas during the gas generation phase in the Eocene time.« less

Mechanism of saline groundwater migration under the influence of deep groundwater exploitation in the North China Plain

NASA Astrophysics Data System (ADS)

Han, D.; Cao, G.; Currell, M. J.

2016-12-01

Understanding the mechanism of salt water transport in response to the exploitation of deep freshwater has long been one of the major regional environmental hydrogeological problems and scientific challenges in the North China Plain. It is also the key to a correct understanding of the sources of deep groundwater pumpage. This study will look at the Hengshui - Cangzhou region as a region with typical vertical salt water distribution, and high levels of groundwater exploitation, integrating a variety of techniques in geology, hydrogeology, geophysics, hydrodynamics, and hydrochemistry - stable isotopes. Information about the problem will be determined using multiple lines of evidence, including field surveys of drilling and water sampling, as well as laboratory experiments and physical and numerical simulations. The project will characterize and depict the migration characteristics of salt water bodies and their relationship with the geological structure and deep ground water resources. The work will reveal the freshwater-saltwater interface shape; determine the mode and mechanism of hydrodynamic transport and salt transport; estimate the vertical migration time of salt water in a thick aquitard; and develop accurate hydrogeological conceptual models. This work will utilize groundwater variable density flow- solute transport numerical models to simulate the water and salt transport processes in vertical one-dimensional (typical bore) and two-dimensional (typical cross-section) space. Both inversion of the downward movement of saltwater caused by groundwater exploitation through history, and examining future saltwater migration trends under groundwater exploitation scenarios will be conducted, to quantitatively evaluate the impact of salt water migration to the deep groundwater body in the North China Plain. The research results will provide a scientific basis for the sustainable utilization of deep groundwater resources in this area.

Shark predation on migrating adult American eels (Anguilla rostrata) in the Gulf of St. Lawrence.

PubMed

Béguer-Pon, Mélanie; Benchetrit, José; Castonguay, Martin; Aarestrup, Kim; Campana, Steven E; Stokesbury, Michael J W; Dodson, Julian J

2012-01-01

In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C-too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for porbeagle sharks.

Vertical migration of plutonium-239 + -240, americium-241 and caesium-137 fallout in a forest soil under spruce.

PubMed

Bunzl, K; Kracke, W; Schimmack, W

1992-03-01

The vertical activity distributions of fallout 238Pu, 239+240Pu, 241Am, 134Cs and 137Cs in a forest soil (Hapludult) were determined at several locations in a spruce stand separately according to their origin (global fallout or Chernobyl fallout). To determine the rate of migration of these radionuclides in each soil horizon, the observed depth profiles of the radionuclides were evaluated with a compartment model. In the top organic horizons (LOf1 and Of2), the migration rates for all radionuclides from both sources were above 0.5 cm per year. In the Oh horizon the migration rates observed for global fallout Pu, Am and Cs were similar (0.2-0.4 cm per year). Compared with Pu, however, the mobility of Am is slightly, but statistically significantly, enhanced. The highest rate in this layer was found for Chernobyl-derived radiocaesium (2 cm per year). In the layers of the mineral horizon (depth 0-2, 2-5 and 5-10 cm) the observed migration rates were very similar for global fallout Pu (0.08-0.7 cm per year) and Am (0.1-2 cm per year). In comparison, the migration rate of global fallout radiocaesium was about half in each layer. The highest rate was observed again for Chernobyl-derived radiocaesium (0.5-3 cm per year).

Movement patterns and trajectories of ovigerous blue crabs Callinectes sapidus during the spawning migration

NASA Astrophysics Data System (ADS)

Carr, Sarah D.; Tankersley, Richard A.; Hench, James L.; Forward, Richard B.; Luettich, Richard A.

2004-08-01

Female blue crabs ( Callinectes sapidus Rathbun) migrate from low salinity estuarine regions to high salinity regions near the ocean to release larvae. During this migration, ovigerous females use ebb-tide transport, a vertical migratory behavior in which they ascend into the water column during ebb tides, to move seaward to larval release areas. In order to determine the relationship of ebb-tide vertical migrations to local currents and the influence of these vertical migrations on the horizontal transport of blue crabs in the estuary, ovigerous females with mature embryos (˜1-3 days from hatching) were tracked near Beaufort Inlet, North Carolina (USA), in July and August 2001 and 2002. Crabs were tagged and tracked using ultrasonic telemetry, and currents near the crabs were measured simultaneously with a shipboard acoustic Doppler current profiler. During the two seasons, eight crabs were successfully tracked for periods ranging from 3.9-37.0 h and for distances ranging from 1.9-10.6 km. All crabs migrated seaward during the tracking periods. Crabs moved episodically during all tidal phases with periods of movement on the order of minutes to an hour. They moved with local currents in terms of both speed and direction during ebb tides, consistent with ebb-tide transport, and moved down-estuary (seaward) in opposition to local currents during flood tides. The percentage of time that crabs were active was higher during night ebb tides than during day ebb tides or flood tides and increased with increasing ebb-tide current speed. Mean migratory speeds were 0.11, 0.04, 0.08 and 0.02 m s -1 during night ebb, night flood, day ebb and day flood tides, respectively, and net migratory speeds were on the order of 5 km day -1. Due to the episodic nature of the crabs' movements, the total distances that crabs traveled during ebb tides ranged from 10-40% of the distances that passive particles could have traveled under the same conditions.

Where have all the females gone? Male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) in alpine lakes

NASA Astrophysics Data System (ADS)

Žibrat, U.; Brancelj, A.

2009-04-01

In populations with both males and females sex-ratio is one of the driving forces of population dynamics. It influences fecundity, inbreeding and social interactions. Sex-ratio is affected by several biotic and abiotic factors, either by selective killing of one sex or by inducing migrations. In alpine lakes of Triglav National Park, Slovenia, an extremely male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) was regularly observed since 1992. We analysed population dynamics and sex-ratio of A. alpinus in three alpine lakes (Jezero v Ledvicah, Rjavo jezero and Zgornje Kriško jezero) from Triglav National Park in Slovenia. In addition to seasonal dynamics we also researched long-term changes in sex-ratio (in a period of 11 years from autumn samples) as a result of increased air-temperature, and zooplankton diurnal vertical migrations. Adults of both sexes were found to appear at the same time in the water collumn with males prevailing throughout the season. A similar trend was found in copepodites CV. The percent of adult females began increasing in late summer, when there were no more copepodites and recrutation from copepodites CV to adults stopped, while male mortality increased. All cohorts of A. alpinus were found to perform diurnal vertical migrations. Both adult and CV females remained close to the bottom during the day and migrated vertically during the night. Results of the long-term study show no changes in sex-ratio in autumn.

Seasonal migration and environmental conditions of Pacific halibut Hippoglossus stenolepis, elucidated from pop-up archival transmitting (PAT) tags

USGS Publications Warehouse

Loher, Timothy; Seitz, Andrew C.

2006-01-01

Pop-up archival transmitting (PAT) tags were used to study the fall migration of halibut in the Gulf of Alaska (GOA). We tagged 6 Pacific halibut Hippoglossus stenolepis on summer feeding grounds in the eastern GOA and another 6 in the western GOA from June 13 to August 6, 2002. The tags were programed to be released from the fish on January 15, 2003, at the height of the winter spawning season: 10 tags successfully detached, transmitted archived environmental data (depth and temperature), and generated accurate latitude–longitude coordinates shortly after pop-up; 2 tags deployed off SE Alaska were lost. The tags revealed that 6 fish had moved a considerable distance (>200 km) between tagging and pop-up, and all of these had moved northward to some extent. The longest of the observed migrations was from the southern Alaska Peninsula to Yakutat Bay, a linear displacement of 1153 km; 4 fish showed little evidence of geographic displacement, exhibiting migrations that ranged only from 30 to 69 km. Although 2 fish had moved inshore by the end of the tagging period, all other fish had moved offshore regardless of their overall migration distance. The precise timing of offshore movements varied, beginning as early as August and as late as January. These observations generally corroborate conventional tagging, indicating migration of halibut toward winter spawning grounds in the northern GOA, and movement of fish to deep water in fall. However, no single stereotypic migration behavior was apparent, and a variety of vertical movement patterns and temperature profiles were observed. Halibut spent most time in waters of 5 to 7°C, but experienced temperatures ranging from 2.6 to 11.6°C. Depth observations ranged from 0 to 736 m, with summertime activity concentrated in depths from 0 to 400 m, and halibut that exhibited offshore movement were typically observed at 300 to 700 m by mid-winter. Vertical movement (short-period changes in depth) varied among fish and over time, with some fish displaying little vertical activity, others displaying short periods of activity, and still others displaying considerable activity throughout their time at liberty.

75 FR 22736 - Notice of Request for Applications for the Veterinary Medicine Loan Repayment Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-30

... (RFA) at http://www.nifa.usda.gov/vmlrp . DATES: The FY 2010 Veterinary Medicine Loan Repayment Program (VMLRP) application package has been made available at http://www.nifa.usda.gov/vmlrp and applications... http://www.nslds.ed.gov . Individuals who consolidated their DVM loans with non-educational loans or...

STS-58 crewmembers participate in baseline data collection

NASA Image and Video Library

1993-09-29

S93-45371 (29 Sept 1993) --- Astride the bicycle ergometer, Martin J. (Marty) Fettman, DVM, breathes quietly into the cardiovascular re-breathing unit during the resting phase of an experiment. The payload specialist for the Spacelab Life Sciences (SLS-2) mission was participating with six NASA astronauts, also assigned to STS-58, for data collection and training.

78 FR 63408 - Petition To Amend Animal Welfare Act Regulations To Prohibit Public Contact With Big Cats, Bears...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

... Regulations To Prohibit Public Contact With Big Cats, Bears, and Nonhuman Primates AGENCY: Animal and Plant... into direct or physical contact with big cats, bears, or nonhuman primates of any age, to define the... coming. FOR FURTHER INFORMATION CONTACT: Dr. Barbara Kohn, DVM, Senior Staff Officer, USDA, APHIS, Animal...

Horizontal and vertical movements of Caribbean reef sharks (Carcharhinus perezi): conservation implications of limited migration in a marine sanctuary

PubMed Central

Howey, Lucy A.; Tolentino, Emily R.; Jordan, Lance K. B.; Ruppert, Jonathan L. W.; Brooks, Edward J.

2017-01-01

Despite the ecological and economic importance of the Caribbean reef shark (Carcharhinus perezi), little data exist regarding the movements and habitat use of this predator across its range. We deployed 11 pop-up satellite archival tags on Caribbean reef sharks captured in the northeast Exuma Sound, The Bahamas, to assess their horizontal and vertical movements throughout the water column. Sharks showed high site fidelity to The Bahamas suggesting Bahamian subpopulations remain protected within the Bahamian Shark Sanctuary. Depth data indicate that Caribbean reef sharks spent a significant proportion (72–91%) of their time above 50 m in narrow vertical depth bands, which varied considerably on an individual basis. This may be indicative of high site fidelity to specific bathymetric features. Animals exhibited three broadly categorized sporadic off-bank excursions (more than 50 m excursions) down to a depth of 436.1 m, which were more frequent during the night. These deeper excursions during night may be indicative of foraging in relation to prey on mesophotic reefs, as well as diel-vertically migrating prey from the deeper meso- and bathypelagic zones. These vertical movements suggest that Caribbean reef sharks can be significant vectors of ecosystem connectivity further warranting holistic multi-system management and conservation approaches. PMID:28386422

Three-dimensional modelling of leachate recirculation using vertical wells in bioreactor landfills.

PubMed

Feng, Shi-Jin; Chen, Zheng-Wei; Cao, Ben-Yi

2016-12-01

Bioreactor landfills use leachate recirculation to enhance the biodegradation of municipal solid waste and accelerate landfill stabilisation, which can provide significant environmental and economic benefits. Vertical wells are operated as a major method for leachate recirculation systems. The objectives of this article are to analyse the leachate migration in bioreactor landfills using vertical wells and to offer theoretical basis for the design of leachate recirculation systems. A three-dimensional numerical model was built using FLAC-3D, and this model can consider the saturated and unsaturated flow of leachate within anisotropic waste to reflect the actual conditions. First, main influence factors of leachate migration were analysed, including the vertical well height, hydraulic conductivity, and anisotropic coefficient, in a single-well recirculation system. Then, the effects of different configurations of a group-well system were studied and the optimal well spacing was obtained. Some key design parameters (e.g. the recirculation flow rate, volume of impact zone, radius of impact zone and time to reach steady state) were also evaluated. The results show that the hydraulic conductivity has a great impact on the optimal height of vertical wells and uniform configuration is the best option in terms of both volume of impact zone and time to reach steady state. © The Author(s) 2016.

Horizontal and vertical movements of Caribbean reef sharks (Carcharhinus perezi): conservation implications of limited migration in a marine sanctuary.

PubMed

Shipley, Oliver N; Howey, Lucy A; Tolentino, Emily R; Jordan, Lance K B; Ruppert, Jonathan L W; Brooks, Edward J

2017-02-01

Despite the ecological and economic importance of the Caribbean reef shark ( Carcharhinus perezi ), little data exist regarding the movements and habitat use of this predator across its range. We deployed 11 pop-up satellite archival tags on Caribbean reef sharks captured in the northeast Exuma Sound, The Bahamas, to assess their horizontal and vertical movements throughout the water column. Sharks showed high site fidelity to The Bahamas suggesting Bahamian subpopulations remain protected within the Bahamian Shark Sanctuary. Depth data indicate that Caribbean reef sharks spent a significant proportion (72-91%) of their time above 50 m in narrow vertical depth bands, which varied considerably on an individual basis. This may be indicative of high site fidelity to specific bathymetric features. Animals exhibited three broadly categorized sporadic off-bank excursions (more than 50 m excursions) down to a depth of 436.1 m, which were more frequent during the night. These deeper excursions during night may be indicative of foraging in relation to prey on mesophotic reefs, as well as diel-vertically migrating prey from the deeper meso- and bathypelagic zones. These vertical movements suggest that Caribbean reef sharks can be significant vectors of ecosystem connectivity further warranting holistic multi-system management and conservation approaches.

Vertical migrations of a deep-sea fish and its prey.

PubMed

Afonso, Pedro; McGinty, Niall; Graça, Gonçalo; Fontes, Jorge; Inácio, Mónica; Totland, Atle; Menezes, Gui

2014-01-01

It has been speculated that some deep-sea fishes can display large vertical migrations and likely doing so to explore the full suite of benthopelagic food resources, especially the pelagic organisms of the deep scattering layer (DSL). This would help explain the success of fishes residing at seamounts and the increased biodiversity found in these features of the open ocean. We combined active plus passive acoustic telemetry of blackspot seabream with in situ environmental and biological (backscattering) data collection at a seamount to verify if its behaviour is dominated by vertical movements as a response to temporal changes in environmental conditions and pelagic prey availability. We found that seabream extensively migrate up and down the water column, that these patterns are cyclic both in short-term (tidal, diel) as well as long-term (seasonal) scales, and that they partially match the availability of potential DSL prey components. Furthermore, the emerging pattern points to a more complex spatial behaviour than previously anticipated, suggesting a seasonal switch in the diel behaviour mode (benthic vs. pelagic) of seabream, which may reflect an adaptation to differences in prey availability. This study is the first to document the fine scale three-dimensional behaviour of a deep-sea fish residing at seamounts.

High Altitude Bird Migration at Temperate Latitudes: A Synoptic Perspective on Wind Assistance

PubMed Central

Dokter, Adriaan M.; Shamoun-Baranes, Judy; Kemp, Michael U.; Tijm, Sander; Holleman, Iwan

2013-01-01

At temperate latitudes the synoptic patterns of bird migration are strongly structured by the presence of cyclones and anticyclones, both in the horizontal and altitudinal dimensions. In certain synoptic conditions, birds may efficiently cross regions with opposing surface wind by choosing a higher flight altitude with more favourable wind. We observed migratory passerines at mid-latitudes that selected high altitude wind optima on particular nights, leading to the formation of structured migration layers at varying altitude up to 3 km. Using long-term vertical profiling of bird migration by C-band Doppler radar in the Netherlands, we find that such migration layers occur nearly exclusively during spring migration in the presence of a high-pressure system. A conceptual analytic framework providing insight into the synoptic patterns of wind assistance for migrants that includes the altitudinal dimension has so far been lacking. We present a simple model for a baroclinic atmosphere that relates vertical profiles of wind assistance to the pressure and temperature patterns occurring at temperate latitudes. We show how the magnitude and direction of the large scale horizontal temperature gradient affects the relative gain in wind assistance that migrants obtain through ascending. Temperature gradients typical for northerly high-pressure systems in spring are shown to cause high altitude wind optima in the easterly sectors of anticyclones, thereby explaining the frequent observations of high altitude migration in these synoptic conditions. Given the recurring synoptic arrangements of pressure systems across temperate continents, the opportunities for exploiting high altitude wind will differ between flyways, for example between easterly and westerly oceanic coasts. PMID:23300969

High altitude bird migration at temperate latitudes: a synoptic perspective on wind assistance.

PubMed

Dokter, Adriaan M; Shamoun-Baranes, Judy; Kemp, Michael U; Tijm, Sander; Holleman, Iwan

2013-01-01

At temperate latitudes the synoptic patterns of bird migration are strongly structured by the presence of cyclones and anticyclones, both in the horizontal and altitudinal dimensions. In certain synoptic conditions, birds may efficiently cross regions with opposing surface wind by choosing a higher flight altitude with more favourable wind. We observed migratory passerines at mid-latitudes that selected high altitude wind optima on particular nights, leading to the formation of structured migration layers at varying altitude up to 3 km. Using long-term vertical profiling of bird migration by C-band Doppler radar in the Netherlands, we find that such migration layers occur nearly exclusively during spring migration in the presence of a high-pressure system. A conceptual analytic framework providing insight into the synoptic patterns of wind assistance for migrants that includes the altitudinal dimension has so far been lacking. We present a simple model for a baroclinic atmosphere that relates vertical profiles of wind assistance to the pressure and temperature patterns occurring at temperate latitudes. We show how the magnitude and direction of the large scale horizontal temperature gradient affects the relative gain in wind assistance that migrants obtain through ascending. Temperature gradients typical for northerly high-pressure systems in spring are shown to cause high altitude wind optima in the easterly sectors of anticyclones, thereby explaining the frequent observations of high altitude migration in these synoptic conditions. Given the recurring synoptic arrangements of pressure systems across temperate continents, the opportunities for exploiting high altitude wind will differ between flyways, for example between easterly and westerly oceanic coasts.

Cross-correlation least-squares reverse time migration in the pseudo-time domain

NASA Astrophysics Data System (ADS)

Li, Qingyang; Huang, Jianping; Li, Zhenchun

2017-08-01

The least-squares reverse time migration (LSRTM) method with higher image resolution and amplitude is becoming increasingly popular. However, the LSRTM is not widely used in field land data processing because of its sensitivity to the initial migration velocity model, large computational cost and mismatch of amplitudes between the synthetic and observed data. To overcome the shortcomings of the conventional LSRTM, we propose a cross-correlation least-squares reverse time migration algorithm in pseudo-time domain (PTCLSRTM). Our algorithm not only reduces the depth/velocity ambiguities, but also reduces the effect of velocity error on the imaging results. It relieves the accuracy requirements on the migration velocity model of least-squares migration (LSM). The pseudo-time domain algorithm eliminates the irregular wavelength sampling in the vertical direction, thus it can reduce the vertical grid points and memory requirements used during computation, which makes our method more computationally efficient than the standard implementation. Besides, for field data applications, matching the recorded amplitudes is a very difficult task because of the viscoelastic nature of the Earth and inaccuracies in the estimation of the source wavelet. To relax the requirement for strong amplitude matching of LSM, we extend the normalized cross-correlation objective function to the pseudo-time domain. Our method is only sensitive to the similarity between the predicted and the observed data. Numerical tests on synthetic and land field data confirm the effectiveness of our method and its adaptability for complex models.

Deep scattering layer migration and composition: observations from a diving saucer.

PubMed

Barham, E G

1966-03-18

The distribution of a myctophid fish and physonect siphonophores observed during dives in the Soucoupe off Baja California closely correlates with scattering layers recorded simultaneously with a 12-kcy/sec echo sounder. These organisms were observed while they were migrating vertically, and at their night and daytime levels. They are capable of rapid, extensive changes in depth.

The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain.

PubMed

Wood, Curtis R; Chapman, Jason W; Reynolds, Donald R; Barlow, Janet F; Smith, Alan D; Woiwod, Ian P

2006-03-01

Insects migrating at high altitude over southern Britain have been continuously monitored by automatically operating, vertical-looking radars over a period of several years. During some occasions in the summer months, the migrants were observed to form well-defined layer concentrations, typically at heights of 200-400 m, in the stable night-time atmosphere. Under these conditions, insects are likely to have control over their vertical movements and are selecting flight heights that are favourable for long-range migration. We therefore investigated the factors influencing the formation of these insect layers by comparing radar measurements of the vertical distribution of insect density with meteorological profiles generated by the UK Meteorological Office's (UKMO) Unified Model (UM). Radar-derived measurements of mass and displacement speed, along with data from Rothamsted Insect Survey light traps, provided information on the identity of the migrants. We present here three case studies where noctuid and pyralid moths contributed substantially to the observed layers. The major meteorological factors influencing the layer concentrations appeared to be: (a) the altitude of the warmest air, (b) heights corresponding to temperature preferences or thresholds for sustained migration and (c) on nights when air temperatures are relatively high, wind-speed maxima associated with the nocturnal jet. Back-trajectories indicated that layer duration may have been determined by the distance to the coast. Overall, the unique combination of meteorological data from the UM and insect data from entomological radar described here show considerable promise for systematic studies of high-altitude insect layering.

Numerical modeling of fracking fluid migration through fault zones and fractures in the North German Basin

NASA Astrophysics Data System (ADS)

Pfunt, Helena; Houben, Georg; Himmelsbach, Thomas

2016-09-01

Gas production from shale formations by hydraulic fracturing has raised concerns about the effects on the quality of fresh groundwater. The migration of injected fracking fluids towards the surface was investigated in the North German Basin, based on the known standard lithology. This included cases with natural preferential pathways such as permeable fault zones and fracture networks. Conservative assumptions were applied in the simulation of flow and mass transport triggered by a high pressure boundary of up to 50 MPa excess pressure. The results show no significant fluid migration for a case with undisturbed cap rocks and a maximum of 41 m vertical transport within a permeable fault zone during the pressurization. Open fractures, if present, strongly control the flow field and migration; here vertical transport of fracking fluids reaches up to 200 m during hydraulic fracturing simulation. Long-term transport of the injected water was simulated for 300 years. The fracking fluid rises vertically within the fault zone up to 485 m due to buoyancy. Progressively, it is transported horizontally into sandstone layers, following the natural groundwater flow direction. In the long-term, the injected fluids are diluted to minor concentrations. Despite the presence of permeable pathways, the injected fracking fluids in the reported model did not reach near-surface aquifers, either during the hydraulic fracturing or in the long term. Therefore, the probability of impacts on shallow groundwater by the rise of fracking fluids from a deep shale-gas formation through the geological underground to the surface is small.

Migration of 137Cs in the soil of sloping semi-natural ecosystems in Northern Greece.

PubMed

Arapis, G D; Karandinos, M G

2004-01-01

In the present study, the 137Cs concentration in the soil of sloping semi-natural ecosystems at four different regions of Western Macedonia in Greece was measured 10 years after the Chernobyl accident. These regions were highly polluted due to the deposition of radionuclides escaped during the accident. The concentrations of 137Cs measured were found to differ significantly among the four regions. The rates of both horizontal and vertical migration in the soil were also evaluated. The vertical migration velocity of 137Cs was found to range from 0.1 to 0.3 cm per year, in the most contaminated areas. Consequently, 10 years following the Chernobyl accident, the bulk of 137Cs deposited over the surface of the studied areas in Greece was found to be restricted in the upper 5 cm layer of soil. Regarding the horizontal migration, in most of the sampling sites, we did not detect any displacement or trend to movement of radiocaesium on the surface from the upper to the lower levels of the slopes. Instead, we recorded decreased concentrations of 137Cs with the decrease of altitude.

Effect of plant trichomes on the vertical migration of Haemonchus contortus infective larvae on five tropical forages.

PubMed

Oliveira, Aruaque L F; Costa, Ciniro; Rodella, Roberto A; Silva, Bruna F; Amarante, Alessandro F T

2009-06-01

The influence of trichomes on vertical migration and survival of Haemonchus contortus infective larvae (L3) on different forages was investigated. Four different forages showing different distributions of trichomes (Brachiaria brizantha cv. Marandu, Brachiaria brizantha cv. Xaraes, Andropogon gayanus, and Stylosanthes spp.), and one forage species without trichomes (Panicum maximum cv. Tanzania), were used. Forages cut at the post-grazing height were contaminated with faeces containing L3. Samples of different grass strata (0-10, 10-20, >20 cm) and faeces were collected for L3 quantification once per week over four weeks. In all forages studied, the highest L3 recovery occurred seven days after contamination, with the lowest recovery on A. gayanus. In general, larvae were found on all forages' strata. However, most of the larvae were at the lower stratum. There was no influence of trichomes on migration and survival of H. contortus L3 on the forages.

78 FR 78983 - Office of the Director, National Institutes of Health; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-27

... in sections 552b(c)(4), and 552b(c)(6), Title 5 U.S.C., as amended. The grant applications and the... 20892. Contact Person: Franziska Grieder, DVM, Ph.D., Executive Secretary, Director, Office of Research... example, a government-issued photo ID, driver's license, or passport) and to state the purpose of their...

Neuro-Immune Mechanisms in Response to Venezuelan Equine Encephalitis Virus Infection

DTIC Science & Technology

2000-01-01

iii ABSTRACT NEURO-IMMUNE MECHANISMS IN RESPONSE TO VENEZUELAN EQUINE ENCEPHALITIS VIRUS INFECTION Major Bruce A. Schoneboom directed by Franziska B...Grieder, DVM, Ph.D., Assistant Professor of Microbiology and Immunology, Molecular and Cellular Biology, and Neuroscience Venezuelan equine ...3. DATES COVERED - 4. TITLE AND SUBTITLE NEURO-IMMUNE MECHANISMS IN RESPONSE TO VENEZUELAN EQUINE ENCEPHALITIS VIRUS INFECTION 5a. CONTRACT

Overview of hydro-acoustic current-measurement applications by the U.S. geological survey in Indiana

USGS Publications Warehouse

Morlock, Scott E.; Stewart, James A.

1999-01-01

The U.S. Geological Survey (USGS) maintains a network of 170 streamflow-gaging stations in Indiana to collect data from which continuous records of river discharges are produced. Traditionally, the discharge record from a station is produced by recording river stage and making periodic discharge measurements through a range of stage, then developing a relation between stage and discharge. Techniques that promise to increase data collection accuracy and efficiency include the use of hydro-acoustic instrumentation to measure river velocities. The velocity measurements are used to compute river discharge. In-situ applications of hydro-acoustic instruments by the USGS in Indiana include acoustic velocity meters (AVM's) at six streamflow-gaging stations and newly developed Doppler velocity meters (DVM's) at two stations. AVM's use reciprocal travel times of acoustic signals to measure average water velocities along acoustic paths, whereas DVM's use the Doppler shift of backscattered acoustic signals to compute water velocities. In addition to the in-situ applications, three acoustic Doppler current profilers (ADCP's) are used to make river-discharge measurements from moving boats at streamflow-gaging stations in Indiana. The USGS has designed and is testing an innovative unmanned platform from which to make ADCP discharge measurements.

Exploring Shyness among Veterinary Medical Students: Implications for Mental and Social Wellness.

PubMed

Royal, Kenneth; Hedgpeth, Mari-Wells; Flammer, Keven

2018-06-15

Shyness is defined as "the tendency to feel awkward, worried or tense during social encounters, especially with unfamiliar people." While shyness is not necessarily a social disorder, extreme cases of shyness may classify as a social phobia and require medical treatment. Extant research has noted shyness may be correlated with social problems that could be detrimental to one's health, career, and social relationships. This exploratory study examined the prevalence, source, and nature of shyness among incoming Doctor of Veterinary Medicine (DVM) program students at one veterinary medical school. One hundred first-year DVM program students were administered a modified version of the Survey on Shyness. Results indicate most students (85%) self-identified as at least a little shy, a figure that is believed to be significantly higher than national population norms in the United States. Students attributed the primary source of shyness to personal fears and insecurities. Students reported frequent feelings of shyness and generally perceived shyness as an undesirable quality. Students reported that strangers, acquaintances, authority figures, and classmates often make them feel shy. Given the high prevalence of self-reported shyness among veterinary medical students, institutions may wish to include strategies to address shyness as part of a comprehensive wellness program.

Vertically migrating swimmers generate aggregation-scale eddies in a stratified column.

PubMed

Houghton, Isabel A; Koseff, Jeffrey R; Monismith, Stephen G; Dabiri, John O

2018-04-01

Biologically generated turbulence has been proposed as an important contributor to nutrient transport and ocean mixing 1-3 . However, to produce non-negligible transport and mixing, such turbulence must produce eddies at scales comparable to the length scales of stratification in the ocean. It has previously been argued that biologically generated turbulence is limited to the scale of the individual animals involved 4 , which would make turbulence created by highly abundant centimetre-scale zooplankton such as krill irrelevant to ocean mixing. Their small size notwithstanding, zooplankton form dense aggregations tens of metres in vertical extent as they undergo diurnal vertical migration over hundreds of metres 3,5,6 . This behaviour potentially introduces additional length scales-such as the scale of the aggregation-that are of relevance to animal interactions with the surrounding water column. Here we show that the collective vertical migration of centimetre-scale swimmers-as represented by the brine shrimp Artemia salina-generates aggregation-scale eddies that mix a stable density stratification, resulting in an effective turbulent diffusivity up to three orders of magnitude larger than the molecular diffusivity of salt. These observed large-scale mixing eddies are the result of flow in the wakes of the individual organisms coalescing to form a large-scale downward jet during upward swimming, even in the presence of a strong density stratification relative to typical values observed in the ocean. The results illustrate the potential for marine zooplankton to considerably alter the physical and biogeochemical structure of the water column, with potentially widespread effects owing to their high abundance in climatically important regions of the ocean 7 .

Age-specific light preferences and vertical migration patterns of a Great Lakes invasive invertebrate, Hemimysis anomala

USGS Publications Warehouse

Boscarino, Brent T.; Halpin, Kathleen E.; Rudstam, Lars G.; Walsh, Maureen G.; Lantry, Brian F.

2012-01-01

We use a combination of spectral sensitivity analyses, laboratory behavioral observations and field distributions of a vertically migrating invertebrate, Hemimysis anomala (a recent invasive species to the Laurentian Great Lakes of North America), to determine if light preference and timing of emergence has an ontogenetic component. Juvenile Hemimysis (−3.4 and 10−2.4 mylux— a Hemimysis-specific unit of brightness derived from visual pigment analyses (wavelength of maximum absorbance = 500 nm; 1 mylux ~ 159 lx). These preferred light levels are equivalent to those present during nautical twilight on the Earth's surface and were several orders of magnitude brighter than those most preferred by adults (> 4.5 mm) in the laboratory (10−6.4 to 10−7.4 mylux). Both size classes completely avoided light levels of 10−0.4 mylux and greater, which are representative of daytime light levels at the Earth's surface. Net hauls taken at ~ 20-min intervals from sunset to the end of nautical twilight on two sampling occasions on Seneca Lake, New York (sampling depth = 2 m) revealed that juveniles emerged into the water column during civil twilight. Adult Hemimysis emerged later during nautical twilight when juveniles had already reached their maximum abundance in the water column. Laboratory-derived light preferences successfully predicted the timing of emergence and time of maximal abundance of both size classes on both sampling occasions. This study is one of the first to demonstrate that Hemimysis diel vertical migration has an ontogenetic component and to report the specific light levels likely to initiate and limit vertical movements.

A comparison of mesopelagic mesozooplankton community structure in the subtropical and subarctic North Pacific Ocean

NASA Astrophysics Data System (ADS)

Steinberg, Deborah K.; Cope, Joseph S.; Wilson, Stephanie E.; Kobari, T.

2008-07-01

Mesopelagic mesozooplankton communities of an oligotrophic (Hawaii Ocean Time series-HOT station ALOHA) and a mesotrophic (Japanese time-series station K2) environment in the North Pacific Ocean are compared as part of a research program investigating the factors that control the efficiency of particle export to the deep sea (VERtical Transport In the Global Ocean—VERTIGO). We analyzed zooplankton (>350 μm) collected from net tows taken between 0 and 1000 m at each site to investigate the biomass size structure and the abundance of the major taxonomic groups in discrete depth intervals throughout the water column. Biomass of zooplankton at K2 over all depths was approximately an order of a magnitude higher than at ALOHA, with a significantly higher proportion of the biomass at K2 in the larger (>2 mm) size classes. This difference was mostly due to the abundance at K2 of the large calanoid copepods Neocalanus spp. and Eucalanus bungii, which undergo ontogenetic (seasonal) vertical migration. The overall strength of diel vertical migration was higher at K2, with a mean night:day biomass ratio in the upper 150 m of 2.5, vs. a ratio of 1.7 at ALOHA. However, the amplitude of the diel migration (change in weighted mean depth between day and night) was higher at ALOHA for all biomass size classes, perhaps due to deeper light penetration causing deeper migration to avoid visual predators. A number of taxa known to feed on suspended or sinking detritus showed distinct peaks in the mesopelagic zone, which affects particle transport efficiency at both sites. These taxa include calanoid and poecilostomatoid (e.g., Oncaea spp.) copepods, salps, polychaetes, and phaeodarian radiolaria at K2, harpacticoid copepods at ALOHA, and ostracods at both sites. We found distinct layers of carnivores (mainly gelatinous zooplankton) in the mesopelagic at K2 including chaetognaths, hydrozoan medusae, polychaetes, and gymnosome pteropods, and, in the upper mesopelagic zone, of ctenophores and siphonophores; at both sites a mesopelagic layer of hyperiid amphipods was found. The large population of ontogenetically migrating calanoid copepods is likely supporting large carnivorous populations at depth at K2. The contrasting zooplankton taxonomic structure at the two sites helps explain the higher efficiency of the biological pump at K2. Factors responsible for increased transport efficiency at K2 include rapid transport of POC via larger fecal pellets produced by zooplankton at K2, and enhanced active carbon export at K2 vs. ALOHA, due to the greater strength of diel vertical migration and to additional ontogenetic migration at K2.

Regional-scale brine migration along vertical pathways due to CO2 injection - Part 1: The participatory modeling approach

NASA Astrophysics Data System (ADS)

Scheer, Dirk; Konrad, Wilfried; Class, Holger; Kissinger, Alexander; Knopf, Stefan; Noack, Vera

2017-06-01

Saltwater intrusion into potential drinking water aquifers due to the injection of CO2 into deep saline aquifers is one of the potential hazards associated with the geological storage of CO2. Thus, in a site selection process, models for predicting the fate of the displaced brine are required, for example, for a risk assessment or the optimization of pressure management concepts. From the very beginning, this research on brine migration aimed at involving expert and stakeholder knowledge and assessment in simulating the impacts of injecting CO2 into deep saline aquifers by means of a participatory modeling process. The involvement exercise made use of two approaches. First, guideline-based interviews were carried out, aiming at eliciting expert and stakeholder knowledge and assessments of geological structures and mechanisms affecting CO2-induced brine migration. Second, a stakeholder workshop including the World Café format yielded evaluations and judgments of the numerical modeling approach, scenario selection, and preliminary simulation results. The participatory modeling approach gained several results covering brine migration in general, the geological model sketch, scenario development, and the review of the preliminary simulation results. These results were included in revised versions of both the geological model and the numerical model, helping to improve the analysis of regional-scale brine migration along vertical pathways due to CO2 injection.

Vertical distribution of hydraulic characteristics and water quality in three boreholes in the Galena-Platteville Aquifer at the Parson's Casket Hardware Superfund site, Belvidere, Illinois, 1990

USGS Publications Warehouse

Mills, P.C.

1993-01-01

The U.S. Geological Survey investigated contaminant migration in the Galena-Platteville aquifer at the Parson's Casket Hardware site in Belvidere, Ill. This report presents the results of the first phase of the investigation, from August through December 1990. A packer assembly was used to isolate various depth intervals in three 150-foot-deep boreholes in the dolomite aquifer. Aquifer-test data include vertical distributions of vertical hydraulic gradient, horizontal hydraulic conductivity (K), and response of water levels in observation wells to borehole pumping. Water-quality data include vertical distributions of field-measured properties and laboratory determinations of concentrations of volatile organic compounds (VOC's). vertical hydraulic gradients in the aquifer were downward. The downward gradients ranged from less than 0.01 to 0.37 foot/foot. The largest gradient was associated with an elevated-K interval at 115 to 125 feet below land surface. The hydraulic characteristics of strata within the aquifer seem to be generally consistent across the site. The strata can be subdivided into five hydraulic units with the following approximate depth ranges-and K's : (1) a 1- to 5-foot-thick weathered surface at about 35 feet below land surface, 1-200 ft/d (feet per day); (2) 35-80 feet, 0.05-0.5 ft/d; (3) 80-115 feet, 0.5 ft/d; (4) 115-125 feet, 0.5-10 ft/d; and (5) 125-150 feet, 0.5 ft/d. Water-level drawdowns were detected in one shallow bedrock observation well during pumping of some of the packed intervals in a nearby borehole, indicating that the degree of vertical connection between some intervals in the aquifer may be greater than that between others. During development pumping of one borehole, drawdowns were detected in a nearby well screened in the lower part of the overlying glacial-drift deposits, indicating hydraulic connection between the glacial drift aquifer and the bedrock aquifer. VOC's were detected throughout the upper half (about 150 feet ) of the bedrock aquifer beneath the site. The detected compounds were predominantly chlorinated ethenes and ethanes (maximum concentration was 570 ppb (parts per billion) of trichloroethylene. There was a positive correlation between concentrations of VOC's, specific conductance, and K. The distribution of VOC concentrations indicate that the low-K dolomite beds in the Galena-Platteville aquifer may impede the downward migration of the VOC's and that the high-K beds and fissures may provide pathways for the lateral migration of VOC's through the aquifer. Contaminant migration is possibly affected by ground-water flow through vertical fractures that connect shallow beds with deeper beds in the aquifer, thus explaining the detections of some VOC species at intermittent depths.

Development and Calibration of a Variable-Density Numerical Model of a Deep-well Injection Site near the Southeastern Florida Coast

NASA Astrophysics Data System (ADS)

Dausman, A.; Langevin, C.; Sukop, M.; Walsh, V.

2006-12-01

The South District Wastewater Treatment Plant (SDWWTP), located in southeastern Miami-Dade County about 1 mi west of the Biscayne Bay coastline, is the largest capacity deep-well injection plant in the United States. Currently, about 100 Mgal/d of partially treated, essentially fresh (less than 1000 mg/L total dissolved solids) effluent is injected through 17 wells (each approximately 2500 ft below land surface) into the highly transmissive, lower-temperature, saline Boulder Zone composed of highly fractured dolomite. A thin confining unit called the Delray Dolomite, which is 8-16 ft thick, overlies the intended injection zone at the site. Although the Delray Dolomite has a vertical hydraulic conductivity estimated between 0.001 and 0.00001 ft/d, well casings for 10 of the 17 wells do not extend beneath the unit. A 700-ft-thick middle confining unit, with estimated vertical hydraulic conductivities between 0.1 and 28 ft/d, overlies the Delray Dolomite and separates it from the Upper Floridan aquifer. Protected by the Safe Drinking Water Act (SDWA), the Upper Floridan aquifer contains water that is less than 10,000 mg/L total dissolved solids. In southern Florida, this aquifer is used for reverse osmosis, blending with other waters, and as a reservoir for aquifer storage and recovery. At the SDWWTP, ammonia concentrations that exceed background conditions have been observed in monitoring wells open in and above the middle confining unit, indicating upward vertical migration of effluent, possibly toward the Upper Floridan aquifer. The U.S. Geological Survey currently is developing a variable-density groundwater flow and solute transport model for the Floridan aquifer system in Miami-Dade County. This model includes the injection of treated wastewater at the SDWWTP. The developed numerical model uses SEAWAT, a code that calculates variable- density flow as a function of salinity, to capture the buoyancy effects at the site and along the coast. Simulation efforts have been designed to determine likely mechanisms for vertical fluid migration as well as predict future movement of the effluent. Two alternative mechanisms for upward fluid migration are being tested with the model: (1) site-wide, diffuse upward movement through the Delray Dolomite and middle confining unit with all 17 injection wells; and (2) localized upward movement from the shallow casing depths at 10 of the 17 wells. The parameter estimation program, PEST, has estimated two different hydraulic conductivity configurations for the Delray Dolomite, middle confining unit, and other layers under these two possible conditions. The different parameter sets have yielded two satisfactory model calibrations. Results of these calibrations indicate that vertical effluent migration potentially is occurring either from (1) the 10 wells open above the Delray Dolomite, with virtually no effluent migration through the Delray Dolomite; or (2) all 17 wells open above and below the Delray Dolomite, with effluent migration through the Delray Dolomite.

Imaging Faults in Carbonate Reservoir using Full Waveform Inversion and Reverse Time Migration of Walkaway VSP Data

NASA Astrophysics Data System (ADS)

Takam Takougang, E. M.; Bouzidi, Y.

2016-12-01

Multi-offset Vertical Seismic Profile (walkaway VSP) data were collected in an oil field located in a shallow water environment dominated by carbonate rocks, offshore the United Arab Emirates. The purpose of the survey was to provide structural information of the reservoir, around and away from the borehole. Five parallel lines were collected using an air gun at 25 m shot interval and 4 m source depth. A typical recording tool with 20 receivers spaced every 15.1 m, and located in a deviated borehole with an angle varying between 0 and 24 degree from the vertical direction, was used to record the data. The recording tool was deployed at different depths for each line, from 521 m to 2742 m depth. Smaller offsets were used for shallow receivers and larger offsets for deeper receivers. The lines merged to form the input dataset for waveform tomography. The total length of the combined lines was 9 km, containing 1344 shots and 100 receivers in the borehole located half-way down. Acoustic full waveform inversion was applied in the frequency domain to derive a high resolution velocity model. The final velocity model derived after the inversion using the frequencies 5-40 Hz, showed good correlation with velocities estimated from vertical incidence VSP and sonic log, confirming the success of the inversion. The velocity model showed anomalous low values in areas that correlate with known location of hydrocarbon reservoir. Pre-stack depth Reverse time migration was then applied using the final velocity model from waveform inversion and the up-going wavefield from the input data. The final estimated source signature from waveform inversion was used as input source for reverse time migration. To save computational memory and time, every 3 shots were used during reverse time migration and the data were low-pass filtered to 30 Hz. Migration artifacts were attenuated using a second order derivative filter. The final migration image shows a good correlation with the waveform tomography velocity model, and highlights a complex network of faults in the reservoir, that could be useful in understanding fluid and hydrocarbon movements. This study shows that the combination of full waveform tomography and reverse time migration can provide high resolution images that can enhance interpretation and characterization of oil reservoirs.

Vertical Migration of Radionuclides in Soils on the Chernobyl Nuclear Power Plant (ChNPP) Exclusion Zone (1987-2007)

NASA Astrophysics Data System (ADS)

Jannik, G. T.; Ivanov, Y. A.; Kashparov, V. A.; Levchuk, S. E.; Bondarkov, M. D.; Maksymenko, A. M.; Farfan, E. B.; Marra, J. C.

2009-12-01

In 1986-1987, a set of experimental sites for studies of vertical migration of radionuclides released from the ChNPP was established in the ChNPP Exclusion Zone for various fallout plumes. The sites were selected considering local terrain and geo-chemical conditions, as well as physical and chemical characteristics of the fallout. The experimental sites included grasslands, and pre-Chernobyl cultivated meadows and croplands. Vertical migration of radionuclides in the ChNPP Exclusion Zone grasslands was evaluated. Parameters of 137Cs, 90Sr, and 239,240Pu transfer were calculated and the periods during which these radionuclides reach their ecological half-life in the upper 5 cm soil layer were estimated. Migration capabilities of these radionuclides in the grassland soils tend to decrease as follows: 90Sr >137Cs ≥ 239,240Pu. A significant retardation of the 137Cs vertical migration was shown in the grasslands long after the Chernobyl accident. During the 21st year after the fallout, average Tecol values for 137Cs (the period of time it takes in the environment for 137Cs to reach half the value of its original concentration in the upper 5 cm soil layer, regardless of physical decay) are as follows: 180 - 320 years for grassland containing automorphous mineral soils of a light granulometric composition; and 90 - 100 years for grassland containing hydromorphous organogenic soils. These values are significantly higher than those estimated for the period of 6-9 years after the fallout: 60 - 150 years and 11 - 20 years, respectively. The absolute 137Cs Tecol values are by factors of 3-7 higher than 137Cs radiological decay values long after the accident. Changes in the exposure dose resulting from the soil deposited 137Cs only depend on its radiological decay. This factor should necessarily be considered for development of predictive assessments, including dose exposures for the hypothetical population in case of their re-evacuation to the exclusion areas. The obtained results have to be considered for predictive assessments, including those for dose exposures for the hypothetical population in case of their re-evacuation to the exclusion areas if implementation and/or planning of remediation activities at the ChNPP Exclusion Zone are considered reasonable and appropriate.

Vertical distribution of 137Cs in grassland soils disturbed by moles (Talpa europaea L.).

PubMed

Ramzaev, V; Barkovsky, A

2018-04-01

Activity of biota is one of the factors influencing vertical migration of radionuclides deposited from the atmosphere onto the ground surface. The goal of this work was to study the vertical distribution of 137 Cs in grassland soils disturbed by moles (Talpa europaea L.) in comparison with undisturbed grassland soils. Field observations and soil sampling were carried out in the areas of eight settlements in the Klintsovskiy, Krasnogorskiy and Novozybkovskiy districts of the Bryansk region, Russia in six years during the period 1999-2016. The study sites had been heavily contaminated by Chernobyl fallout in 1986. Activity of 137 Cs in soil samples was determined by γ-ray spectrometry. 137 Cs surface ground contamination levels at the studied plots (n = 17) ranged from 327 kBq m -2 to 2360 kBq m -2 with a mean of 1000 kBq m -2 and a median of 700 kBq m -2 . The position of the 137 Cs migration centre in the soil in 2010-2016 was significantly (the Mann-Whitney U test, P < .01) deeper at mole-disturbed plots (median = 5.99 cm or 6.64 g cm -2 , n = 6) compared to the undisturbed ones (median = 2.48 cm or 2.35 g cm -2 , n = 6). The 137 Cs migration rate at mole-disturbed plots (median = 0.26 g cm -2  y -1 , mean = 0.31 g cm -2  y -1 ) was significantly higher (by a factor of 3) than at undisturbed plots (median = 0.08 g cm -2  y -1 , mean = 0.10 g cm -2  y -1 ). The difference in the migration rates between the mole-disturbed and undisturbed plots (median = 0.18 g cm -2  y -1 , mean = 0.21 g cm -2  y -1 ) reasonably corresponded to the mass of soil that might be ejected by moles per unit area per year. The results of this study indicate that the burrowing activity of moles has increased vertical migration of Chernobyl-derived radiocaesium in the grassland soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Migration without migraines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lines, L.; Burton, A.; Lu, H.X.

Accurate velocity models are a necessity for reliable migration results. Velocity analysis generally involves the use of methods such as normal moveout analysis (NMO), seismic traveltime tomography, or iterative prestack migration. These techniques can be effective, and each has its own advantage or disadvantage. Conventional NMO methods are relatively inexpensive but basically require simplifying assumptions about geology. Tomography is a more general method but requires traveltime interpretation of prestack data. Iterative prestack depth migration is very general but is computationally expensive. In some cases, there is the opportunity to estimate vertical velocities by use of well information. The well informationmore » can be used to optimize poststack migrations, thereby eliminating some of the time and expense of iterative prestack migration. The optimized poststack migration procedure defined here computes the velocity model which minimizes the depth differences between seismic images and formation depths at the well by using a least squares inversion method. The optimization methods described in this paper will hopefully produce ``migrations without migraines.``« less

Acute Oral Toxicity of Nitroguanidine in Male and Female Rats

DTIC Science & Technology

1988-03-01

results place nitroguanidlne in the practically nontoxic category based on the toxicity classification system of Hodge and Sterner. 20 DISTRIBUTION...nose and mouth. These results place nitroguanidine in the practically nontoxic category based on the toxicity classification system of Hodge and...O. Lollini, DVM, VC, Diplomate, American College of Veterinary Pathologists DATA MANAGERS: Carolyn M. Lewis, MS, Yvonne C. Le Tellier , BS REPORT

National Biocontainment Training Center

DTIC Science & Technology

2016-10-01

and the high containment capabilities of the Galveston National Laboratory. U.S. Food and Drug Administration Training – Marisa Hickey, D.V.M., MPH...in the Netherlands focused specifically on “healthy food and healthy environment.” The CVI is the national reference laboratory that is focused on...the health of both animals and humans. They provide research for government and commercial entities on animal diseases that threaten the food supply

2008 Homeland Security S and T Stakeholders Conference West. Volume 4. Wednesday

DTIC Science & Technology

2008-01-16

www.npia.police.uk Polonium 210 Interoperability - lessons Major Incident - CBRN Images courtesy of BBC www.npia.police.uk Boscastle 2007...Washington Training Session 37: Preparing First Responders for Food Systems Disasters Jerry Gillespie, DVM, PhD Director, Western Institute for... Food Safety and Security Training Session 39: Technology Adoption & Innovation 1 Dr. Neal Thornberry, Innovation Chair Graduate School of

Neuro-Immune Mechanisms in Response to Venezuelan equine encephalitis Virus Infection

DTIC Science & Technology

2000-05-01

horses . They were subsequently shown to be previously unrecognized viral agents of severe equine encephalitis (Smith et al., 1997). One member of...iii ABSTRACT NEURO-IMMUNE MECHANISMS IN RESPONSE TO VENEZUELAN EQUINE ENCEPHALITIS VIRUS INFECTION Major Bruce A. Schoneboom directed by Franziska B...Grieder, DVM, Ph.D., Assistant Professor of Microbiology and Immunology, Molecular and Cellular Biology, and Neuroscience Venezuelan equine

Tidal and seasonal effects on transport of pink shrimp postlarvae

USGS Publications Warehouse

Criales, Maria M.; Wang, Jingyuan; Browder, Joan A.; Robblee, M.B.

2005-01-01

Transport simulations were conducted to investigate a large seasonal peak in postlarvae of the pink shrimp Farfantepenaeus duorarum that occurs every summer on the northwestern border of Florida Bay. Daily vertical migration, a known behavior in pink shrimp postlarvae, was assumed in all scenarios investigated. A Lagrangian trajectory model was developed using a current field derived from a 3 yr ADCP (Acoustic Doppler Current Profiler) time series. To fit the estimated planktonic development time of pink shrimp, the model simulated larvae traveling at night over a 30 d period. We investigated 2 types of effects: (1) the effect of mismatch periodicity between tidal constituents and daily migration, and (2) the effect of seasonal changes in night length. The maximum eastward displacement with the semidiurnal lunar tidal constituent (M2) was 4 km, with periods of enhanced transport in both summer and winter. In contrast, eastward displacement with the semidiurnal solar tidal constituent (S2) and the lunisolar diurnal K1 was 65 km and the period of maximum distance occurred in summer every year. Because the periods of S2 and K1 are so close to the 24 h vertical migration period, and the eastward current (flood) of these constituents matches the diel cycle over extended intervals, they can induce strong horizontal transport during summer. Thus, diel vertical migration can interact with the S2 and the K1 tidal constituents and with the annual cycle of night length to produce a distinct annual cycle that may enhance transport of pink shrimp and other coastal species during summer in shallow areas of the Gulf of Mexico. ?? Inter-Research 2005.

Natural attenuation of Fukushima-derived radiocesium in soils due to its vertical and lateral migration.

PubMed

Konoplev, A; Golosov, V; Wakiyama, Y; Takase, T; Yoschenko, V; Yoshihara, T; Parenyuk, O; Cresswell, A; Ivanov, M; Carradine, M; Nanba, K; Onda, Y

2018-06-01

Processes of vertical and lateral migration lead to gradual reduction in contamination of catchment soil, particularly its top layer. The reduction can be considered as natural attenuation. This, in turn, results in a gradual decrease of radiocesium activity concentrations in the surface runoff and river water, in both dissolved and particulate forms. The purpose of this research is to study the dynamics of Fukushima-derived radiocesium in undisturbed soils and floodplain deposits exposed to erosion and sedimentation during floods. Combined observations of radiocesium vertical distribution in soil and sediment deposition on artificial lawn-grass mats on the Niida River floodplain allowed us to estimate both annual mean sediment accumulation rates and maximum sedimentation rates corresponding to an extreme flood event during Tropical Storm Etau, 6-11 September 2015. Dose rates were reduced considerably for floodplain sections with high sedimentation because the top soil layer with high radionuclide contamination was eroded and/or buried under cleaner fresh sediments produced mostly due to bank erosion and sediments movements. Rate constants of natural attenuation on the sites of the Takase River and floodplain of Niida River was found to be in range 0.2-0.4 year -1 . For the site in the lower reach of the Niida River, collimated shield dose readings from soil surfaces slightly increased during the period of observation from February to July 2016. Generally, due to more precipitation, steeper slopes, higher temperatures and increased biological activities in soils, self-purification of radioactive contamination in Fukushima associated with vertical and lateral radionuclide migration is faster than in Chernobyl. In many cases, monitored natural attenuation along with appropriate restrictions seems to be optimal option for water remediation in Fukushima contaminated areas. Copyright © 2017. Published by Elsevier Ltd.

Investigation of water seepage through porous media using X-ray imaging technique

NASA Astrophysics Data System (ADS)

Jung, Sung Yong; Lim, Seungmin; Lee, Sang Joon

2012-07-01

SummaryDynamic movement of wetting front and variation of water contents through three different porous media were investigated using X-ray radiography. Water and natural sand particles were used as liquid and porous media in this study. To minimize the effects of minor X-ray attenuation and uneven illumination, the flat field correction (FFC) was applied before determining the position of wetting front. In addition, the thickness-averaged (in the direction of the X-ray penetration) water content was obtained by employing the Beer-Lambert law. The initial inertia of water droplet influences more strongly on the vertical migration, compared to the horizontal migration. The effect of initial inertia on the horizontal migration is enhanced as sand size decreases. The pattern of water transport is observed to be significantly affected by the initial water contents. As the initial water contents increases, the bulb-type transport pattern is shifted to a trapezoidal shape. With increasing surface temperature, water droplets are easily broken on the sand surface. This consequently decreases the length of the initial inertia region. Different from the wetting front migration, the water contents at the initial stage clearly exhibit a preferential flow along the vertical direction. The water transport becomes nearly uniform in all directions beyond the saturation state.

Preparative electrophoresis of cultured human cells: Effect of cell cycle phase

NASA Technical Reports Server (NTRS)

Kunze, M. E.; Todd, P. W.; Goolsby, C. L.; Walker, J. T.

1985-01-01

Human epithelioid T-1E cells were cultured in suspension and subjected to density gradient electrophoresis upward in a vertical column. It is indicated that the most rapidly migrating cells were at the beginning of the cell cycle and the most slowly migrating cells were at the end of the cell cycle. The fastest migrating cells divided 24 hr later than the slowest migrating cells. Colonies developing from slowly migrating cells had twice as many cells during exponential growth as did the most rapidly migrating cells, and the numbers of cells per colony at any time was inversely related to the electrophoretic migration rate. The DNA measurements by fluorescence flow cytometry indicates that the slowest migrating cell populations are enriched in cells that have twice as much DNA as the fastest migrating cells. It is concluded that electrophoretic mobility of these cultured human cells declines steadily through the cell cycle and that the mobility is lowest at the end of G sub 2 phase and highest at the beginning of G sub 1 phase.

Behavioral tradeoff in estuarine larvae favors seaward migration over minimizing visibility to predators

PubMed Central

Morgan, Steven G.; Anastasia, Jean R.

2008-01-01

The ability of microscopic larvae to control their fate and replenish populations in dynamic marine environments has been a long-running topic of debate of central importance to understanding the ecology and evolution of life in the sea and managing resources in a changing global environment. After decades of research documenting behaviors that keep larvae close to natal populations, it is becoming apparent that larval behaviors in a broader spectrum of species promote long-distance migrations to offshore nursery grounds. Larvae must exert considerable control over their movements. We now show that larval emigration from estuaries is favored even over minimizing visibility to predators. An endogenous tidal vertical migration that would expedite seaward migration of Uca pugilator larvae was maintained experimentally across two tidal regimes. The periodicity of the rhythm doubled to match the local tidal regime, but larvae ascended to the surface during the daytime rather than at night. This process would conserve larval emigration but increase the visibility to predators across part of the species range. The periodicity of tidal vertical migration by Sesarma cinereum larvae failed to double and was inappropriately timed relative to both environmental cycles in the absence of a diel cycle. The timing system regulating tidally timed behaviors in these two species of crabs evidently differed. Phenotypic plasticity can conserve larval transport of both species when tidal and diel cycles are present. It may be widespread in the sea where diverse habitats are encountered across extensive species ranges. PMID:18172217

Behavioral tradeoff in estuarine larvae favors seaward migration over minimizing visibility to predators.

PubMed

Morgan, Steven G; Anastasia, Jean R

2008-01-08

The ability of microscopic larvae to control their fate and replenish populations in dynamic marine environments has been a long-running topic of debate of central importance to understanding the ecology and evolution of life in the sea and managing resources in a changing global environment. After decades of research documenting behaviors that keep larvae close to natal populations, it is becoming apparent that larval behaviors in a broader spectrum of species promote long-distance migrations to offshore nursery grounds. Larvae must exert considerable control over their movements. We now show that larval emigration from estuaries is favored even over minimizing visibility to predators. An endogenous tidal vertical migration that would expedite seaward migration of Uca pugilator larvae was maintained experimentally across two tidal regimes. The periodicity of the rhythm doubled to match the local tidal regime, but larvae ascended to the surface during the daytime rather than at night. This process would conserve larval emigration but increase the visibility to predators across part of the species range. The periodicity of tidal vertical migration by Sesarma cinereum larvae failed to double and was inappropriately timed relative to both environmental cycles in the absence of a diel cycle. The timing system regulating tidally timed behaviors in these two species of crabs evidently differed. Phenotypic plasticity can conserve larval transport of both species when tidal and diel cycles are present. It may be widespread in the sea where diverse habitats are encountered across extensive species ranges.

Guiding out-migrating juvenile sea lamprey (Petromyzon marinus) with pulsed direct current

USGS Publications Warehouse

Johnson, Nicholas S.; Miehls, Scott M.

2014-01-01

Non-physical stimuli can deter or guide fish without affecting water flow or navigation and therefore have been investigated to improve fish passage at anthropogenic barriers and to control movement of invasive fish. Upstream fish migration can be blocked or guided without physical structure by electrifying the water, but directional downstream fish guidance with electricity has received little attention. We tested two non-uniform pulsed direct current electric systems, each having different electrode orientations (vertical versus horizontal), to determine their ability to guide out-migrating juvenile sea lamprey (Petromyzon marinus) and rainbow trout (Oncorhynchus mykiss). Both systems guided significantly more juvenile sea lamprey to a specific location in our experimental raceway when activated than when deactivated, but guidance efficiency decreased at the highest water velocities tested. At the electric field setting that effectively guided sea lamprey, rainbow trout were guided by the vertical electrode system, but most were blocked by the horizontal electrode system. Additional research should characterize the response of other species to non-uniform fields of pulsed DC and develop electrode configurations that guide fish over a range of water velocity.

Study on cyclic injection gas override in condensate gas reservoir

NASA Astrophysics Data System (ADS)

Sun, Yan; Zhu, Weiyao; Xia, Jing; Li, Baozhu

2018-02-01

Cyclic injection gas override in condensate gas reservoirs for the large density difference between injection gas and condensate gas has been studied, but no relevant mathematical models have been built. In this paper, a mathematical model of cyclic injection gas override in condensate gas reservoir is established, considering density difference between the injected gas and the remaining condensate gas in the formation. The vertical flow ratio and override degree are used to reflect the override law of injected dry gas. Combined with the actual data of Tarim gas condensate reservoir, the parameters of injected dry gas override are calculated and analysed. The results show that the radial pressure rises or falls rapidly and the pressure gradient varies greatly in the near wells. The radial pressure varies slowly and the pressure gradient changes little in the reservoir which is within a certain distance from the wells. In the near injection well, the injected dry gas mainly migrates along the radial direction, and the vertical migration is relatively not obvious. With the distance from the injection well, the vertical flow ratio and override degree of injected dry gas increases, and the vertical flow ratio reaches the maximum in the middle of the injection well and the production well.

Prior Health Care Utilization as a Potential Determinant of Enrollment in a 21-Year Prospective Study, the Millennium Cohort Study

DTIC Science & Technology

2008-01-10

studies Military medicine Military personnel Response bias Veterans Abbreviations CI Confidence interval ICD-9- CM International...DVM, MPH and Tomoko I Hooper, MD MPH (Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences...hospitalization. In contrast, the decision to seek outpatient care may be a personal decision to seek con- sultation, preventive medicine , or medical

MYOCARDIAL INJURY FROM INHALED COMBUSTION PARTICLES: IS THERE A ROLE FOR ZINC?

EPA Science Inventory

Myocardial injury from inhaled combustion particles: Is there a role for zinc?
U.P.Kodavanti, PhD 1, C.F.Moyer, PhD, DVM 2, A.D.Ledbetter, BS 1, M.C.Schladweiler, BS
1, P.S.Gilmour, PhD 1, R.Hauser, ScD, MPH 3, D.C.Christiani, MPH, MS 3, D.L.Costa, ScD
1 and A.Ny...

Integrated Hydrogeological Model of the General Separations Area, Vol. 2, Rev. 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

FLACH, GREGORYK.

1999-04-01

The 15 mi2 General Separations Area (GSA) contains more than 35 RCRA and CERCLA waste units, and is the focus of numerous ongoing and anticipated contaminant migration and remedial alternatives studies. To meet the analysis needs of GSA remediation programs, a groundwater flow model of the area based on the FACT code was developed. The model is consistent with detailed characterization and monitoring data through 1996. Model preprocessing has been automated so that future updates and modifications can be performed quickly and efficiently. Most remedial action scenarios can be explicitly simulated, including vertical recirculation wells, vertical barriers, surface caps, pumpingmore » wells at arbitrary locations, specified drawdown within well casings (instead of flowrate), and wetland impacts of remedial actions. The model has a fine scale vertical mesh and heterogeneous conductivity field, and includes the vadose zone. Therefore, the model is well suited to support subsequent contaminant transport simulations. the model can provide a common framework for analyzing groundwater flow, contaminant migration, and remedial alternatives across Environmental Restoration programs within the GSA.« less

Vertical structure of larval fish assemblages during diel cycles in summer and winter in the southern part of Bahía de La Paz, México

NASA Astrophysics Data System (ADS)

Aceves-Medina, Gerardo; Saldierna-Martínez, Ricardo; Hinojosa-Medina, Alejandro; Jiménez-Rosenberg, Sylvia P. A.; Hernández-Rivas, Martín E.; Morales-Ávila, Raúl

2008-03-01

The effect of environmental variables on the vertical structure of larval fish assemblages in a tropical coastal lagoon was analyzed. Ichthyoplankton samples were collected from the near-bottom and surface strata near the mouth of a subtropical lagoon during contrasting seasonal conditions of temperature, photoperiod, light intensity, and tidal heights. During summer, larval fish assemblages had high species richness ( R) and were dominated by tropical species. During winter, assemblages had lower R values and were dominated by subtropical and temperate species. Vertical distribution patterns of the taxa were determined by the interaction of environmental variables and behavior of each species to maintain their position in a stratum in the water column, or to achieve vertical migrations induced by environmental stimuli that, in this case, were thermal gradient, column water stratification, and intensity of light. Depth position and vertical migration of fish larvae, coupled with the flood and ebb tide conditions, played an important role in their retention and displacement toward the lagoon. Fish larvae with distribution restricted to the inner part of the inlet, such as Achirus mazatlanus, Etropus sp., and several gobies, were more abundant in the near-bottom stratum during the ebb tide, allowing them to avoid exportation, whereas those that could spawn outside, but depended on the inlet as a nursery area, were more abundant near the surface during flood tide, such as Abudefduf troschelii and Stegastes rectifraenum.

A tidal explanation for the sunrise/sunset anomaly in HALOE low-latitude nitric oxide observations

NASA Astrophysics Data System (ADS)

Marsh, Daniel R.; Russell, James M., III

2000-10-01

The difference in sunrise and sunset low-latitude nitric oxide (NO) mixing ratios in the mesosphere and lower thermosphere (MLT) is shown to be consistent with a perturbation induced by the migrating diurnal tide. The vertical wind of the tide can induce factor of 2 changes over 12 hours at the equator. The vertical, latitudinal and temporal structure of NO perturbations closely matches the structure of vertical winds from a tidal model. In addition, previous observations of the seasonal and interannual variation in the tidal wind appear to correlate with NO variations.

Arroyo channel head evolution in a flash-flood-dominated discontinuous ephemeral stream system

USGS Publications Warehouse

DeLong, Stephen B.; Johnson, Joel P.L.; Whipple, Kelin X.

2014-01-01

We study whether arroyo channel head retreat in dryland discontinuous ephemeral streams is driven by surface runoff, seepage erosion, mass wasting, or some combination of these hydrogeomorphic processes. We monitored precipitation, overland flow, soil moisture, and headcut migration over several seasonal cycles at two adjacent rangeland channel heads in southern Arizona. Erosion occurred by headward retreat of vertical to overhanging faces, driven dominantly by surface runoff. No evidence exists for erosion caused by shallow-groundwater–related processes, even though similar theater-headed morphologies are sometimes attributed to seepage erosion by emerging groundwater. At our field site, vertical variation in soil shear strength influenced the persistence of the characteristic theater-head form. The dominant processes of erosion included removal of grains and soil aggregates during even very shallow (1–3 cm) overland flow events by runoff on vertical to overhanging channel headwalls, plunge-pool erosion during higher-discharge runoff events, immediate postrunoff wet mass wasting, and minor intra-event dry mass wasting on soil tension fractures developing subparallel to the headwall. Multiple stepwise linear regression indicates that the migration rate is most strongly correlated with flow duration and total precipitation and is poorly correlated with peak flow depth or time-integrated flow depth. The studied channel heads migrated upslope with a self-similar morphologic form under a wide range of hydrological conditions, and the most powerful flash floods were not always responsible for the largest changes in landscape form in this environment. 

Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles.

PubMed

Seibel, Brad A; Schneider, Jillian L; Kaartvedt, Stein; Wishner, Karen F; Daly, Kendra L

2016-10-01

The effects of regional variations in oxygen and temperature levels with depth were assessed for the metabolism and hypoxia tolerance of dominant euphausiid species. The physiological strategies employed by these species facilitate prediction of changing vertical distributions with expanding oxygen minimum zones and inform estimates of the contribution of vertically migrating species to biogeochemical cycles. The migrating species from the Eastern Tropical Pacific (ETP), Euphausia eximia and Nematoscelis gracilis, tolerate a Partial Pressure (PO2) of 0.8 kPa at 10 °C (∼15 µM O2) for at least 12 h without mortality, while the California Current species, Nematoscelis difficilis, is incapable of surviving even 2.4 kPa PO2 (∼32 µM O2) for more than 3 h at that temperature. Euphausia diomedeae from the Red Sea migrates into an intermediate oxygen minimum zone, but one in which the temperature at depth remains near 22 °C. Euphausia diomedeae survived 1.6 kPa PO2 (∼22 µM O2) at 22 °C for the duration of six hour respiration experiments. Critical oxygen partial pressures were estimated for each species, and, for E. eximia, measured via oxygen consumption (2.1 kPa, 10 °C, n = 2) and lactate accumulation (1.1 kPa, 10 °C). A primary mechanism facilitating low oxygen tolerance is an ability to dramatically reduce energy expenditure during daytime forays into low oxygen waters. The ETP and Red Sea species reduced aerobic metabolism by more than 50% during exposure to hypoxia. Anaerobic glycolytic energy production, as indicated by whole-animal lactate accumulation, contributed only modestly to the energy deficit. Thus, the total metabolic rate was suppressed by ∼49-64%. Metabolic suppression during diel migrations to depth reduces the metabolic contribution of these species to vertical carbon and nitrogen flux (i.e., the biological pump) by an equivalent amount. Growing evidence suggests that metabolic suppression is a widespread strategy among migrating zooplankton in oxygen minimum zones and may have important implications for the economy and ecology of the oceans. The interacting effects of oxygen and temperature on the metabolism of oceanic species facilitate predictions of changing vertical distribution with climate change. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Vertically-integrated Approaches for Carbon Sequestration Modeling

NASA Astrophysics Data System (ADS)

Bandilla, K.; Celia, M. A.; Guo, B.

2015-12-01

Carbon capture and sequestration (CCS) is being considered as an approach to mitigate anthropogenic CO2 emissions from large stationary sources such as coal fired power plants and natural gas processing plants. Computer modeling is an essential tool for site design and operational planning as it allows prediction of the pressure response as well as the migration of both CO2 and brine in the subsurface. Many processes, such as buoyancy, hysteresis, geomechanics and geochemistry, can have important impacts on the system. While all of the processes can be taken into account simultaneously, the resulting models are computationally very expensive and require large numbers of parameters which are often uncertain or unknown. In many cases of practical interest, the computational and data requirements can be reduced by choosing a smaller domain and/or by neglecting or simplifying certain processes. This leads to a series of models with different complexity, ranging from coupled multi-physics, multi-phase three-dimensional models to semi-analytical single-phase models. Under certain conditions the three-dimensional equations can be integrated in the vertical direction, leading to a suite of two-dimensional multi-phase models, termed vertically-integrated models. These models are either solved numerically or simplified further (e.g., assumption of vertical equilibrium) to allow analytical or semi-analytical solutions. This presentation focuses on how different vertically-integrated models have been applied to the simulation of CO2 and brine migration during CCS projects. Several example sites, such as the Illinois Basin and the Wabamun Lake region of the Alberta Basin, are discussed to show how vertically-integrated models can be used to gain understanding of CCS operations.

Remembering Joseph Mayo and His Contributions to Animal Science | Poster

Cancer.gov

By Carolynne Keenan, Guest Writer In the 1990s, when Joseph Mayo, D.V.M, ran out of gas leading coworkers home from a meeting in Bethesda, he pulled over to the side of the road on I-270 and waited for help. He didn’t have to wait long; within a few minutes a passing motorist took pity on the group of scientists and offered them a lift back to Fort Detrick.

State and Local Policy Considerations for Implementing the National Response Plan

DTIC Science & Technology

2005-03-01

has actually increased the vulnerability of cattle, swine, sheep , and some wildlife and zoo animals because the various species have lost any resistance...The virus affects cloven-hoofed animals including cattle, sheep , goats, and swine. An outbreak of FMD represents a threat not only to domesticated...filled with clear fluid) from infected 15 Dr. Radford Davis, DVM, MPH, DACVPM and multiple other sources, although FMD is zoonotic , there have only

Experimental Proteus mirabilis Burn Surface Infection

DTIC Science & Technology

1982-02-01

Reprinted from the Achie of Surgery ECTE February 1982, Volume 117 Copyright 19 2. American Medical Association MAY 2 8 1982 V0A Experimental Proteus ... mirabilis Burn Surface Infection Albert T. McManus, PhD; Charles G. McLeod, Jr, DVM; Arthur D. Mason, Jr, MD * We established a human burn Isolate of... Proteus mirabills as have examined human burn isolates from the genera an experimental pathogen. Infliction of a nonfatal scald injury Enterobacter

Novel Influenza A (H1N1) Outbreak at the U.S. Air Force Academy: Epidemiology and Viral Shedding Duration (American Journal of Preventive Medicine, Volume 20, Number 10, 2009)

DTIC Science & Technology

2009-01-01

and Viral Shedding Duration atherine Takacs Witkop, MD, MPH, Mark R. Duffy, DVM, MPH, Elizabeth A. Macias, PhD, homas F. Gibbons, PhD, James D. Escobar...oseltami- ir two times daily for 5 days if the patients indicated onset of ymptoms no more than 72 hours prior to presentation. pper-class cadets

Integrative Lifecourse and Genetic Analysis of Military Working Dogs

DTIC Science & Technology

2013-10-01

Working Dogs 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-11-2-0225 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) C. Guillermo Couto, DVM, Diplomate...protocol for the collection of biological samples and Lackland veterinary approval was granted ; and final Lackland AFB oversight approval was granted and...those documents were submitted to DoD CDMRP grant administration. Currently, there is one final approval from ACURO pending (and expected

Inactive supply wells as conduits for flow and contaminant migration: conditions of occurrence and suggestions for management

NASA Astrophysics Data System (ADS)

Gailey, Robert M.

2017-11-01

Water supply wells can act as conduits for vertical flow and contaminant migration between water-bearing strata under common hydrogeologic and well construction conditions. While recognized by some for decades, there is little published data on the magnitude of flows and extent of resulting water quality impacts. Consequently, the issue may not be acknowledged widely enough and the need for better management persists. This is especially true for unconsolidated alluvial groundwater basins that are hydrologically stressed by agricultural activities. Theoretical and practical considerations indicate that significant water volumes can migrate vertically through wells. The flow is often downward, with shallow groundwater, usually poorer in quality, migrating through conduit wells to degrade deeper water quality. Field data from locations in California, USA, are presented in combination with modeling results to illustrate both the prevalence of conditions conducive to intraborehole flow and the resulting impacts to water quality. Suggestions for management of planned wells include better enforcement of current regulations and more detailed consideration of hydrogeologic conditions during design and installation. A potentially greater management challenge is presented by the large number of existing wells. Monitoring for evidence of conduit flow and solute transport in areas of high well density is recommended to identify wells that pose greater risks to water quality. Conduit wells that are discovered may be addressed through approaches that include structural modification and changes in operations.

Aquifer susceptibility to perchlorate contamination in a highly urbanized environment

USGS Publications Warehouse

Woolfenden, Linda R.; Trefly, Michael G.

2007-01-01

Perchlorate contamination from anthropogenic sources has been released into the Rialto-Colton, California, USA, groundwater flow system since the 1940s during its production, distribution, storage, and use. Preliminary analysis of lithological, geophysical, and water-chemistry data provided new understanding of the pathways of perchlorate migration that aid in assessing the susceptibility of drinking-water supplies to contamination within the Rialto-Colton basin. Vertical migration of perchlorate into the main water-producing aquifers is restricted by an areally extensive old soil surface; however, perchlorate data indicate contamination below this soil surface. Possible pathways for the downward migration of the contaminated water include wellbore flow and discontinuities in the old soil surface. Horizontal migration of perchlorate is influenced by lithology and faults within the basin. The basin fill is a heterogeneous mixture of boulders, gravel, sand, silt, and clay, and internal faults may restrict perchlorate migration in some areas.

Modeling dissolution and volatilization of LNAPL sources migrating on the groundwater table.

PubMed

Kim, Jeongkon; Corapcioglu, M Yavuz

2003-08-01

A vertically averaged two-dimensional model was developed to describe areal spreading and migration of light nonaqueous-phase liquids (LNAPLs) introduced into the subsurface by spills or leaks from underground storage tanks. The NAPL transport model was coupled with two-dimensional contaminant transport models to predict contamination of soil gas and groundwater resulting from a LNAPL migrating on the water table. Numerical solutions were obtained by using the finite-difference method. Simulations and sensitivity analyses were conducted with a LNAPL of pure benzene to study LNAPL migration and groundwater contamination. The model was applied to subsurface contamination by jet fuel. Results indicated that LNAPL migration were affected mostly by volatilization. The generation and movement of the dissolved plume was affected by the geology of the site and the free-product plume. Most of the spilled mass remained as a free LNAPL phase 20 years after the spill. The migration of LNAPL for such a long period resulted in the contamination of both groundwater and a large volume of soil.

Barriers to and opportunities for landward migration of coastal wetlands with sea-level rise

USGS Publications Warehouse

Enwright, Nicholas M.; Griffith, Kereen T.; Osland, Michael J.

2016-01-01

In the 21st century, accelerated sea-level rise and continued coastal development are expected to greatly alter coastal landscapes across the globe. Historically, many coastal ecosystems have responded to sea-level fluctuations via horizontal and vertical movement on the landscape. However, anthropogenic activities, including urbanization and the construction of flood-prevention infrastructure, can produce barriers that impede ecosystem migration. Here we show where tidal saline wetlands have the potential to migrate landward along the northern Gulf of Mexico coast, one of the most sea-level rise sensitive and wetland-rich regions of the world. Our findings can be used to identify migration corridors and develop sea-level rise adaptation strategies to help ensure the continued availability of wetland-associated ecosystem goods and services.

Multiple Deltas Built Out Over Time

NASA Image and Video Library

2014-12-08

This diagram depicts a vertical cross section through geological layers deposited by rivers, deltas and lakes. Deposits from a series of successive deltas build out increasingly high in elevation as they migrate toward the center of the basin.

Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile.

PubMed

Garavelli, Lysel; Colas, François; Verley, Philippe; Kaplan, David Michael; Yannicelli, Beatriz; Lett, Christophe

2016-01-01

In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient results from the combination of current direction and intensity, seawater temperature, and available habitat. From our simulated connectivity patterns we then identify subpopulations of loco along the Chilean coast, which could serve as a basis for spatial management of this resource in the future.

Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile

PubMed Central

Garavelli, Lysel; Colas, François; Verley, Philippe; Kaplan, David Michael; Yannicelli, Beatriz; Lett, Christophe

2016-01-01

In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient results from the combination of current direction and intensity, seawater temperature, and available habitat. From our simulated connectivity patterns we then identify subpopulations of loco along the Chilean coast, which could serve as a basis for spatial management of this resource in the future. PMID:26751574

[On the effect of partial flooding on 137Cs and 90Sr in forest biogeocenosis].

PubMed

Perevolotskaia, T V; Bulavik, I M; Perevolotskiĭ, A N

2009-01-01

The analysis was made on 137Cs and 90Sr distribution oak, pine and hornbeam plantations depending on different under soil water levels. Intensity of 137Cs and of 90Sr migration along the vertical layers of soils is determined by under soil water level at a specific sampling site. The closer under soil water to the surface of the soil, the lowest radionuclide contamination is in the upper soil levels and the highest radionuclide contamination is in the deeper layers. The "fast" and "slow" quasi diffusion coefficients for 137Cs and for 90Sr and their contribution to the total migration of radionuclide through vertical soil levels were determined. A decrease in 137Cs and increase in 90Sr transfer factors to the elements of overground phytomass as a result of under soil water level lowering was established.

Behavioral and physiological changes around estrus events identified using multiple automated monitoring technologies.

PubMed

Dolecheck, K A; Silvia, W J; Heersche, G; Chang, Y M; Ray, D L; Stone, A E; Wadsworth, B A; Bewley, J M

2015-12-01

This study included 2 objectives. The first objective was to describe estrus-related changes in parameters automatically recorded by the CowManager SensOor (Agis Automatisering, Harmelen, the Netherlands), DVM bolus (DVM Systems LLC, Greeley, CO), HR Tag (SCR Engineers Ltd., Netanya, Israel), IceQube (IceRobotics Ltd., Edinburgh, UK), and Track a Cow (Animart Inc., Beaver Dam, WI). This objective was accomplished using 35 cows in 3 groups between January and June 2013 at the University of Kentucky Coldstream Dairy. We used a modified Ovsynch with G7G protocol to partially synchronize ovulation, ending after the last PGF2α injection (d 0) to allow estrus expression. Visual observation for standing estrus was conducted for four 30-min periods at 0330, 1000, 1430, and 2200h on d 2, 3, 4, and 5. Eighteen of the 35 cows stood to be mounted at least once during the observation period. These cows were used to compare differences between the 6h before and after the first standing event (estrus) and the 2wk preceding that period (nonestrus) for all technology parameters. Differences between estrus and nonestrus were observed for CowManager SensOor minutes feeding per hour, minutes of high ear activity per hour, and minutes ruminating per hour; twice daily DVM bolus reticulorumen temperature; HR Tag neck activity per 2h and minutes ruminating per 2h; IceQube lying bouts per hour, minutes lying per hour, and number of steps per hour; and Track a Cow leg activity per hour and minutes lying per hour. No difference between estrus and nonestrus was observed for CowManager SensOor ear surface temperature per hour. The second objective of this study was to explore the estrus detection potential of machine-learning techniques using automatically collected data. Three machine-learning techniques (random forest, linear discriminant analysis, and neural network) were applied to automatically collected parameter data from the 18 cows observed in standing estrus. Machine learning accuracy for all technologies ranged from 91.0 to 100.0%. When we compared visual observation with progesterone profiles of all 32 cows, we found 65.6% accuracy. Based on these results, machine-learning techniques have potential to be applied to automatically collected technology data for estrus detection. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Using a dynamic vegetation model for future projections of crop yields: application to Belgium in the framework of the VOTES and MASC projects

NASA Astrophysics Data System (ADS)

Jacquemin, Ingrid; Henrot, Alexandra-Jane; Fontaine, Corentin M.; Dendoncker, Nicolas; Beckers, Veronique; Debusscher, Bos; Tychon, Bernard; Hambuckers, Alain; François, Louis

2016-04-01

Dynamic vegetation models (DVM) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil, to study the role of the vegetation in the carbon cycle. These models are now directly coupled with climate models in order to evaluate feedbacks between vegetation and climate. But DVM characteristics allow numerous other applications, leading to amelioration of some of their modules (e.g., evaluating sensitivity of the hydrological module to land surface changes) and developments (e.g., coupling with other models like agent-based models), to be used in ecosystem management and land use planning studies. It is in this dynamic context about DVMs that we have adapted the CARAIB (CARbon Assimilation In the Biosphere) model. One of the main improvements is the implementation of a crop module, allowing the assessment of climate change impacts on crop yields. We try to validate this module at different scales: - from the plot level, with the use of eddy-covariance data from agricultural sites in the FLUXNET network, such as Lonzée (Belgium) or other Western European sites (Grignon, Dijkgraaf,…), - to the country level, for which we compare the crop yield calculated by CARAIB to the crop yield statistics for Belgium and for different agricultural regions of the country. Another challenge for the CARAIB DVM was to deal with the landscape dynamics, which is not directly possible due to the lack of consideration of anthropogenic factors in the system. In the framework of the VOTES and the MASC projects, CARAIB is coupled with an agent-based model (ABM), representing the societal component of the system. This coupled module allows the use of climate and socio-economic scenarios, particularly interesting for studies which aim at ensuring a sustainable approach. This module has particularly been exploited in the VOTES project, where the objective was to provide a social, biophysical and economic assessment of the ecosystem services in four municipalities under urban pressure in the center of Belgium. The biophysical valuation was carried out with the coupled module, allowing a quantitative evaluation of key ecosystem services as a function of three climatic and socio-economic scenarios.

The innate origin of radial and vertical gradients in a simulated galaxy disc

NASA Astrophysics Data System (ADS)

Navarro, Julio F.; Yozin, Cameron; Loewen, Nic; Benítez-Llambay, Alejandro; Fattahi, Azadeh; Frenk, Carlos S.; Oman, Kyle A.; Schaye, Joop; Theuns, Tom

2018-05-01

We examine the origin of radial and vertical gradients in the age/metallicity of the stellar component of a galaxy disc formed in the APOSTLE cosmological hydrodynamical simulations. Some of these gradients resemble those in the Milky Way, where they have sometimes been interpreted as due to internal evolution, such as scattering off giant molecular clouds, radial migration driven by spiral patterns, or orbital resonances with a bar. Secular processes play a minor role in the simulated galaxy, which lacks strong spiral or bar patterns, and where such gradients arise as a result of the gradual enrichment of a gaseous disc that is born thick but thins as it turns into stars and settles into centrifugal equilibrium. The settling is controlled by the feedback of young stars; which links the star formation, enrichment, and equilibration time-scales, inducing radial and vertical gradients in the gaseous disc and its descendent stars. The kinematics of coeval stars evolve little after birth and provide a faithful snapshot of the gaseous disc structure at the time of their formation. In this interpretation, the age-velocity dispersion relation would reflect the gradual thinning of the disc rather than the importance of secular orbit scattering; the outward flaring of stars would result from the gas disc flare rather than from radial migration; and vertical gradients would arise because the gas disc gradually thinned as it enriched. Such radial and vertical trends might just reflect the evolving properties of the parent gaseous disc, and are not necessarily the result of secular evolutionary processes.

Tidally oriented vertical migration and position maintenance of zooplankton in a temperate estuary

USGS Publications Warehouse

Kimmerer, W.J.; Burau, J.R.; Bennett, W.A.

1998-01-01

In many estuaries, maxima in turbidity and abundance of several common species of zooplankton occur in the low salinity zone (LSZ) in the range of 0.5-6 practical salinity units (psu). Analysis of zooplankton abundance from monitoring in 1972-1987 revealed that historical maxima in abundance of the copepod Eurytemora affinis and the mysid Neomysis mercedis, and in turbidity as determined from Secchi disk data, were close to the estimated position of 2 psu bottom salinity. The copepod Sinocalanus doerrii had a maximum slightly landward of that of E. affinis. After 1987 these maxima decreased and shifted to a lower salinity, presumably because of the effects of grazing by the introduced clam Potamocorbula amurensis. At the same time, the copepod Pseudodiaptomus forbesi, the mysid Acanthomysis sp., and amphipods became abundant with peaks at salinity around 0.2-0.5 psu. Plausible mechanisms for maintenance of these persistent abundance peaks include interactions between variation in flow and abundance, either in the vertical or horizontal plane, or higher net population growth rate in the peaks than seaward of the peaks. In spring of 1994, a dry year, we sampled in and near the LSZ using a Lagrangian sampling scheme to follow selected isohalines while sampling over several complete tidal cycles. Acoustic Doppler current profilers were used to provide detailed velocity distributions to enable us to estimate longitudinal fluxes of organisms. Stratification was weak and gravitational circulation nearly absent in the LSZ. All of the common species of zooplankton migrated vertically in response to the tides, with abundance higher in the water column on the flood than on the ebb. Migration of mysids and amphipods was sufficient to override net seaward flow to produce a net landward flux of organisms. Migration of copepods, however, was insufficient to reverse or even greatly diminish the net seaward flux of organisms, implying alternative mechanisms of position maintenance.

Periodic swarms of the salp Salpa aspera in the Slope Water off the NE United States: Biovolume, vertical migration, grazing, and vertical flux

NASA Astrophysics Data System (ADS)

Madin, L. P.; Kremer, P.; Wiebe, P. H.; Purcell, J. E.; Horgan, E. H.; Nemazie, D. A.

2006-05-01

Sampling during four summers over a twenty-seven year period has documented dense populations of Salpa aspera in the Slope Water south of New England, northeastern United States. The salps demonstrated a strong pattern of diel vertical migration, moving to depth (mostly 600-800 m) during the day and aggregating in the epipelagic (<100m) at night. Filtration rates determined from both gut pigment analysis and direct feeding experiments indicated that both the aggregate and solitary stages filtered water at rates ranging from 0.5 to 6lh-1ml-1 biovolume. Maximum displacement volumes of salps measured were 5.7lm-2 in 1986 and 1.6lm-2 in 1993. Depending on the year, the sampled salp populations were calculated to clear between 8 and 74% of the upper 50 m during each 8 h night. Total fecal output for the same populations was estimated to be between 5 and 91mgCm-2night-1. These results, and other observations, suggest this region is a salp "hot spot", with swarms of S. aspera developing seasonally on a frequent basis.

Does a ‘turbophoretic’ effect account for layer concentrations of insects migrating in the stable night-time atmosphere?

PubMed Central

Reynolds, A.M; Reynolds, D.R; Riley, J.R

2008-01-01

Large migrating insects, such as noctuid moths and acridoid grasshoppers, flying within the stable nocturnal boundary layer commonly become concentrated into horizontal layers. These layers frequently occur near the top of the surface temperature inversion where warm fast-moving airflows provide good conditions for downwind migration. On some occasions, a layer may coincide with a higher altitude temperature maximum such as a subsidence inversion, while on others, it may seem unrelated to any obvious feature in the vertical profile of meteorological variables. Insects within the layers are frequently orientated, either downwind or at an angle to the wind, but the mechanisms involved in both layer formation and common orientation have remained elusive. Here, we show through the results of numerical simulations that if insects are treated as neutrally buoyant particles, they tend to be advected by vertical gusts (through the ‘turbophoretic’ mechanism) into layers in the atmosphere where the turbulent kinetic energy has local minima. These locations typically coincide with local maxima in the wind speed and/or air temperature, and they may also provide cues for orientation. However, the degree of layering predicted by this model is very much weaker than that observed in the field. We have therefore hypothesized that insects behave in a way that amplifies the turbophoretic effect by initiating climbs or descents in response to vertical gusts. New simulations incorporating this behaviour demonstrated the formation of layers that closely mimic field observations, both in the degree of concentration in layers and the rate at which they form. PMID:18611845

Unexpected Positive Buoyancy in Deep Sea Sharks, Hexanchus griseus, and a Echinorhinus cookei

PubMed Central

Nakamura, Itsumi; Meyer, Carl G.; Sato, Katsufumi

2015-01-01

We do not expect non air-breathing aquatic animals to exhibit positive buoyancy. Sharks, for example, rely on oil-filled livers instead of gas-filled swim bladders to increase their buoyancy, but are nonetheless ubiquitously regarded as either negatively or neutrally buoyant. Deep-sea sharks have particularly large, oil-filled livers, and are believed to be neutrally buoyant in their natural habitat, but this has never been confirmed. To empirically determine the buoyancy status of two species of deep-sea sharks (bluntnose sixgill sharks, Hexanchus griseus, and a prickly shark, Echinorhinus cookei) in their natural habitat, we used accelerometer-magnetometer data loggers to measure their swimming performance. Both species of deep-sea sharks showed similar diel vertical migrations: they swam at depths of 200–300 m at night and deeper than 500 m during the day. Ambient water temperature was around 15°C at 200–300 m but below 7°C at depths greater than 500 m. During vertical movements, all deep-sea sharks showed higher swimming efforts during descent than ascent to maintain a given swimming speed, and were able to glide uphill for extended periods (several minutes), indicating that these deep-sea sharks are in fact positively buoyant in their natural habitats. This positive buoyancy may adaptive for stealthy hunting (i.e. upward gliding to surprise prey from underneath) or may facilitate evening upward migrations when muscle temperatures are coolest, and swimming most sluggish, after spending the day in deep, cold water. Positive buoyancy could potentially be widespread in fish conducting daily vertical migration in deep-sea habitats. PMID:26061525

Does a 'turbophoretic' effect account for layer concentrations of insects migrating in the stable night-time atmosphere?

PubMed

Reynolds, A M; Reynolds, D R; Riley, J R

2009-01-06

Large migrating insects, such as noctuid moths and acridoid grasshoppers, flying within the stable nocturnal boundary layer commonly become concentrated into horizontal layers. These layers frequently occur near the top of the surface temperature inversion where warm fast-moving airflows provide good conditions for downwind migration. On some occasions, a layer may coincide with a higher altitude temperature maximum such as a subsidence inversion, while on others, it may seem unrelated to any obvious feature in the vertical profile of meteorological variables. Insects within the layers are frequently orientated, either downwind or at an angle to the wind, but the mechanisms involved in both layer formation and common orientation have remained elusive. Here, we show through the results of numerical simulations that if insects are treated as neutrally buoyant particles, they tend to be advected by vertical gusts (through the 'turbophoretic' mechanism) into layers in the atmosphere where the turbulent kinetic energy has local minima. These locations typically coincide with local maxima in the wind speed and/or air temperature, and they may also provide cues for orientation. However, the degree of layering predicted by this model is very much weaker than that observed in the field. We have therefore hypothesized that insects behave in a way that amplifies the turbophoretic effect by initiating climbs or descents in response to vertical gusts. New simulations incorporating this behaviour demonstrated the formation of layers that closely mimic field observations, both in the degree of concentration in layers and the rate at which they form.

Unexpected Positive Buoyancy in Deep Sea Sharks, Hexanchus griseus, and a Echinorhinus cookei.

PubMed

Nakamura, Itsumi; Meyer, Carl G; Sato, Katsufumi

2015-01-01

We do not expect non air-breathing aquatic animals to exhibit positive buoyancy. Sharks, for example, rely on oil-filled livers instead of gas-filled swim bladders to increase their buoyancy, but are nonetheless ubiquitously regarded as either negatively or neutrally buoyant. Deep-sea sharks have particularly large, oil-filled livers, and are believed to be neutrally buoyant in their natural habitat, but this has never been confirmed. To empirically determine the buoyancy status of two species of deep-sea sharks (bluntnose sixgill sharks, Hexanchus griseus, and a prickly shark, Echinorhinus cookei) in their natural habitat, we used accelerometer-magnetometer data loggers to measure their swimming performance. Both species of deep-sea sharks showed similar diel vertical migrations: they swam at depths of 200-300 m at night and deeper than 500 m during the day. Ambient water temperature was around 15°C at 200-300 m but below 7°C at depths greater than 500 m. During vertical movements, all deep-sea sharks showed higher swimming efforts during descent than ascent to maintain a given swimming speed, and were able to glide uphill for extended periods (several minutes), indicating that these deep-sea sharks are in fact positively buoyant in their natural habitats. This positive buoyancy may adaptive for stealthy hunting (i.e. upward gliding to surprise prey from underneath) or may facilitate evening upward migrations when muscle temperatures are coolest, and swimming most sluggish, after spending the day in deep, cold water. Positive buoyancy could potentially be widespread in fish conducting daily vertical migration in deep-sea habitats.

Migration characteristics and early clinical results of the NANOS® short-stem hip arthroplasty.

PubMed

Kaipel, Martin; Grabowiecki, Phillip; Sinz, Katrina; Farr, Sebastian; Sinz, Günter

2015-05-01

Femoral short stems promise essential advantages in total hip arthroplasty. Up to now, only short- and midterm clinical studies exist. Data on early stem migration that could predict later aseptic loosening at an early stage are rare. The purpose of this study was to assess migration patterns and clinical outcome 2 years after hip replacement by a metaphyseal anchored cementless short stem. Migration data and clinical results were prospectively assessed in 49 patients. Clinical outcome was measured using the Harris Hip Score (HHS). Migration analyses were performed using the computer-assisted Einzel-Bild-Roentgen-Analyse (EBRA) system. At 2 years after surgery, none of the implants needed revision, and HHS increased from 47.9 up to 98.1. Of 49 patients, 5 (10%) showed increased vertical stem migration (1.5 mm/2a) that might predict late aseptic loosening. Of 49 stems, 44 (90%) showed stable migration patterns indicating a beneficial long-term outcome. Results of this study confirm the excellent clinical data of previous works. Migration patterns strongly suggest that short-stem arthroplasty is not only an innovative but also a reliable strategy in total hip replacement.

In Vivo Testing of Chemopreventive Agents Using the Dog Model of Spontaneous Prostate Carcinogenesis

DTIC Science & Technology

2003-03-01

Carcinogenesis 6. AUTHOR(S) David J. Waters, Ph.D., DVM 7. PERFORMING ORGANIZATION NAME (S) AND ADDRESS(ES) S. PERFORMING ORGANIZATION Purdue Research...Foundation REPORT NUMBER West Lafayette, IN 47907-1021 E-Mail: waters@vet .purdue .edu 9. SPONSORING / MONITORING 10. SPONSORING I MONITORING AGENCY NAME (S...commercial organizations and trade names in this report do not constitute an official Department of Army endorsement or approval of the products or services

A new method of carboxyhaemoglobin determination.

PubMed Central

Sanderson, J H; Sotheran, M F; Stattersfield, J P

1978-01-01

A quick and accurate method of determining the concentration of carboxyhaemoglobin (COHb) in blood has been developed. The method uses a dual wavelength double beam spectrophotometer in the 1st derivative mode, linked to a digital voltmeter (DVM), with the two beams set 3 nm apart around an isobestic point of reduced haemoglobin (Hbred) and carboxyhaemoglobin at 579 nm. The 1st derivative mode measures the slope, and this slope is proportional to the concentration of COHb. PMID:629892

Organizing vertical layout environments: a forward-looking development strategy for high-rise building projects

NASA Astrophysics Data System (ADS)

Magay, A. A.; Bulgakova, E. A.; Zabelina, S. A.

2018-03-01

The article highlights issues surrounding development of high rise buildings. With the rapid increase of the global population there has been a trend for people to migrate into megacities and has caused the expansion of big city territories. This trend, coupled with the desire for a comfortable living environment, has resulted in numerous problems plaguing the megacity. This article proposes that a viable solution to the problems facing megacities is to create vertical layout environments. Potential options for creating vertical layout environments are set out below including the construction of buildings with atriums. Further, the article puts forth suggested spatial organization of the environment as well as optimal landscaping of high-rise buildings and constructions for the creation of vertical layout environments. Finally, the persuasive reasons for the adoption of vertical layout environments is that it will decrease the amount of developed urban areas, decrease traffic and increase environmental sustainability.

Enhanced Seismic Imaging of Turbidite Deposits in Chicontepec Basin, Mexico

NASA Astrophysics Data System (ADS)

Chavez-Perez, S.; Vargas-Meleza, L.

2007-05-01

We test, as postprocessing tools, a combination of migration deconvolution and geometric attributes to attack the complex problems of reflector resolution and detection in migrated seismic volumes. Migration deconvolution has been empirically shown to be an effective approach for enhancing the illumination of migrated images, which are blurred versions of the subsurface reflectivity distribution, by decreasing imaging artifacts, improving spatial resolution, and alleviating acquisition footprint problems. We utilize migration deconvolution as a means to improve the quality and resolution of 3D prestack time migrated results from Chicontepec basin, Mexico, a very relevant portion of the producing onshore sector of Pemex, the Mexican petroleum company. Seismic data covers the Agua Fria, Coapechaca, and Tajin fields. It exhibits acquisition footprint problems, migration artifacts and a severe lack of resolution in the target area, where turbidite deposits need to be characterized between major erosional surfaces. Vertical resolution is about 35 m and the main hydrocarbon plays are turbidite beds no more than 60 m thick. We also employ geometric attributes (e.g., coherent energy and curvature), computed after migration deconvolution, to detect and map out depositional features, and help design development wells in the area. Results of this workflow show imaging enhancement and allow us to identify meandering channels and individual sand bodies, previously undistinguishable in the original seismic migrated images.

Linearized inversion of multiple scattering seismic energy

NASA Astrophysics Data System (ADS)

Aldawood, Ali; Hoteit, Ibrahim; Zuberi, Mohammad

2014-05-01

Internal multiples deteriorate the quality of the migrated image obtained conventionally by imaging single scattering energy. So, imaging seismic data with the single-scattering assumption does not locate multiple bounces events in their actual subsurface positions. However, imaging internal multiples properly has the potential to enhance the migrated image because they illuminate zones in the subsurface that are poorly illuminated by single scattering energy such as nearly vertical faults. Standard migration of these multiples provides subsurface reflectivity distributions with low spatial resolution and migration artifacts due to the limited recording aperture, coarse sources and receivers sampling, and the band-limited nature of the source wavelet. The resultant image obtained by the adjoint operator is a smoothed depiction of the true subsurface reflectivity model and is heavily masked by migration artifacts and the source wavelet fingerprint that needs to be properly deconvolved. Hence, we proposed a linearized least-square inversion scheme to mitigate the effect of the migration artifacts, enhance the spatial resolution, and provide more accurate amplitude information when imaging internal multiples. The proposed algorithm uses the least-square image based on single-scattering assumption as a constraint to invert for the part of the image that is illuminated by internal scattering energy. Then, we posed the problem of imaging double-scattering energy as a least-square minimization problem that requires solving the normal equation of the following form: GTGv = GTd, (1) where G is a linearized forward modeling operator that predicts double-scattered seismic data. Also, GT is a linearized adjoint operator that image double-scattered seismic data. Gradient-based optimization algorithms solve this linear system. Hence, we used a quasi-Newton optimization technique to find the least-square minimizer. In this approach, an estimate of the Hessian matrix that contains curvature information is modified at every iteration by a low-rank update based on gradient changes at every step. At each iteration, the data residual is imaged using GT to determine the model update. Application of the linearized inversion to synthetic data to image a vertical fault plane demonstrate the effectiveness of this methodology to properly delineate the vertical fault plane and give better amplitude information than the standard migrated image using the adjoint operator that takes into account internal multiples. Thus, least-square imaging of multiple scattering enhances the spatial resolution of the events illuminated by internal scattering energy. It also deconvolves the source signature and helps remove the fingerprint of the acquisition geometry. The final image is obtained by the superposition of the least-square solution based on single scattering assumption and the least-square solution based on double scattering assumption.

Steep-dip seismic imaging of the shallow San Andreas Fault near Parkfield

USGS Publications Warehouse

Hole, J.A.; Catchings, R.D.; St. Clair, K.C.; Rymer, M.J.; Okaya, D.A.; Carney, B.J.

2001-01-01

Seismic reflection and refraction images illuminate the San Andreas Fault to a depth of 1 kilometer. The prestack depth-migrated reflection image contains near-vertical reflections aligned with the active fault trace. The fault is vertical in the upper 0.5 kilometer, then dips about 70° to the southwest to at least 1 kilometer subsurface. This dip reconciles the difference between the computed locations of earthquakes and the surface fault trace. The seismic velocity cross section shows strong lateral variations. Relatively low velocity (10 to 30%), high electrical conductivity, and low density indicate a 1-kilometer-wide vertical wedge of porous sediment or fractured rock immediately southwest of the active fault trace.

STS-58 crewmembers participate in baseline data collection

NASA Image and Video Library

1993-09-29

S93-45369 (29 Sept 1993) --- Training on the pre-breathing assembly, Martin J. (Marty) Fettman, DVM, inhales a predetermined gas composition. A gas analyzer mass spectrometer determines the composition of the gases he exhales. The re-breathing assembly and gas analyzer system are part of an investigation that explores how lung function is altered in space flight. The payload specialist for the Spacelab Life Sciences (SLS-2) mission was participating with six NASA astronauts, also assigned to STS-58, for data collection and training.

KSC-98pc578

NASA Image and Video Library

1998-05-03

STS-90 Mission Specialists Dafydd (Dave) Williams, M.D., with the Canadian Space Agency (left) and Richard Linnehan, D.V.M., inspect the orbiter Columbia's tires in the evening after their midday arrival on May 3, ending their nearly 16-day Neurolab mission. The 90th Shuttle mission was Columbia's 13th landing at the space center and the 43rd KSC landing in the history of the Space Shuttle program. During the mission, the crew conducted research to contribute to a better understanding of the human nervous system

KSC-98pc512

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- STS-90 Mission Specialist Richard Linnehan, D.V.M., is assisted by NASA and United Space Alliance closeout crew members immediately preceding launch for the nearly 17-day Neurolab mission. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. Linnehan and six fellow crew members will shortly enter the orbiter at KSC's Launch Pad 39B, where the Space Shuttle Columbia will lift off during a launch window that opens at 2:19 p.m. EDT, April 17

Prospective Study of Respiratory Infections at the U.S. Naval Academy

DTIC Science & Technology

2001-09-01

conducting the .findings were significant in demonstrating infection cause and study at the U.S. Naval Academy: Tomoko Hooper, MD MPH; Richard Jhe large...leven M, Ursi D, Van Bever H, Quint W, Niesters HG, Goossens H: Detection of disease. J Infect Dis 1992; 166: 365-73. Mycoplasmapneumoniaeby two...6. AUTHORS 5d. Project Number: Gregory C. Gray, MD, MPH; Robert G. Schultz, MD; Gary D. Gackstetter, DVM, 5e. Task Number: PhD; Richard Thomas, MD

Distribution, abundance, and feeding ecology of decapods in the Arabian Sea, with implications for vertical flux

NASA Astrophysics Data System (ADS)

Mincks, Sarah L.; Bollens, Stephen M.; Madin, Laurence P.; Horgan, Erich; Butler, Mari; Kremer, Patricia M.; Craddock, James E.

Macrozooplankton and micronekton samples were collected on two cruises in the Arabian Sea conducted during the Spring Intermonsoon period (May) and the SW Monsoon period (August) of 1995. Discrete depth samples were collected down to depths of 1000-1500 m. Quantitative gut content analyses were performed on four species of decapod shrimps, Gennadas sordidus, Sergia filictum, Sergia creber, and Eupasiphae gilesii, as well as on the pelagic crab Charybdis smithii. Of the shrimps, only S. filictum and S. creber increased significantly in abundance between the Spring Intermonsoon and SW Monsoon seasons. These four species were found at all depths sampled, and most did not appear to be strong vertical migrators. G. sordidus and S. filictum did appear to spread upward at night, especially during the SW Monsoon, but this movement did not include the entire population. S. creber showed signs of diel vertical migration only in some areas. All four shrimp species except, to some degree, S. creber lived almost exclusively within the oxygen minimum zone (150-1000 m), and are likely to have respiratory adaptations that allow them to persist under such conditions. Feeding occurred at all depths throughout these species' ranges, but only modest feeding occurred in the surface layer (0-150 m). G. sordidus appeared to feed continuously throughout the day and night. Estimated contribution of fecal material to vertical flux ranged from <0.01-2.1% of particulate flux at 1000 m for the shrimps and 1.8-3.0% for C. smithii.

Habitat Parameters for Oxygen Minimum Zone Copepods from the Eastern Tropical North Pacific

NASA Astrophysics Data System (ADS)

Wishner, K. F.; Outram, D.; Grassian, B.

2016-02-01

Oxygen minimum zones (OMZs) affect zooplankton distributions and may be expanding in worldwide spatial and vertical extent from climate change. We studied zooplankton (especially copepod) distributions in the Eastern Tropical North Pacific (ETNP) OMZ, using day-night vertically-stratified MOCNESS tows (0-1000m). Habitat parameters (temperature, oxygen, depth) were defined for abundant copepod species and groups. Zooplankton layers, with a unique suite of species, occurred at upper and lower OMZ oxyclines. At the mesopelagic lower oxycline, there was a layer with a characteristic species assemblage and a sharp 10X biomass increase compared to nearby depths. The lower oxycline layer occurred within a narrow very low oxygen concentration (2µM). At two stations with different OMZ vertical extents, the lower oxycline layer depth changed with OMZ thickness, remaining at the same oxygen concentration but different temperature. Life history habitat (diapause depth, temperature) of the copepod Eucalanus inermis was also affected. In the upper water column at the two stations, large diel vertical migrators (fish, euphausiids) descended to taxon-specific daytime depths in the mid OMZ, regardless of oxygen level, but copepod species distributions showed more variability and sensitivity to habitat parameters. We predict that, with moderate OMZ expansion, the lower oxycline community will likely shift depth, thus re-distributing midwater biomass, species, and processes. In the upper water column, large vertical migrator distributions may be less affected, while smaller taxa (copepods) will likely be sensitive to habitat changes. At some point, the ability to withstand these changes may be exceeded for particular taxa, with consequences for assemblages, trophic webs, and export. In keeping with the session theme, we hope to compare our oceanic findings with others' results from coastal hypoxic situations.

Sea level driven marsh expansion in a coupled model of marsh erosion and migration

USGS Publications Warehouse

Kirwan, Matthew L.; Walters, David C.; Reay, William G.; Carr, Joel

2016-01-01

Coastal wetlands are among the most valuable ecosystems on Earth, where ecosystem services such as flood protection depend nonlinearly on wetland size and are threatened by sea level rise and coastal development. Here we propose a simple model of marsh migration into adjacent uplands and couple it with existing models of seaward edge erosion and vertical soil accretion to explore how ecosystem connectivity influences marsh size and response to sea level rise. We find that marsh loss is nearly inevitable where topographic and anthropogenic barriers limit migration. Where unconstrained by barriers, however, rates of marsh migration are much more sensitive to accelerated sea level rise than rates of edge erosion. This behavior suggests a counterintuitive, natural tendency for marsh expansion with sea level rise and emphasizes the disparity between coastal response to climate change with and without human intervention.

The migration law of overlay rock and coal in deeply inclined coal seam with fully mechanized top coal caving.

PubMed

Liu, Jian; Chen, Shan-Le; Wang, Hua-Jun; Li, Yu-Cheng; Geng, Xiaowei

2015-07-01

In a mine area, some environment geotechnics problems always occure, induced by mined-out region such as the subsidence and cracks at ground level, deformation and destruction of buildings, landslides destruction of water resources and the ecological environment. In order to research the migration of surrounding rock and coal in steeply inclined super high seams which used fully mechanized top coal caving, a working face of a certain mine was made as an example, analyzed the migration law of the overlay rock and coal under different caving ratio of fully mechanized top coal caving with numerical simulation analysis. The results suggest that the laws of overlay rock deformation caused by deeply inclined coal seam were different from horizontal coal seam. On the inclined direction, with an increase of dip angle and caving ratio, the vertical displacement of overlay rock and coal became greater, the asymmetric phenomenon of vertical displacement became obvious. On the trend direction, active region and transition region in goaf became smaller along with the increase of mining and caving ratio. On the contrary, the stable region area became greater. Therefore, there was an essential difference between the mechanism of surface movement deformation with deeply inclined coal seam and that with horizontal coal seam.

Ecological differences influence the thermal sensitivity of swimming performance in two co-occurring mysid shrimp species with climate change implications.

PubMed

Ober, Gordon T; Thornber, Carol; Grear, Jason; Kolbe, Jason J

2017-02-01

Temperature strongly affects performance in ectotherms. As ocean warming continues, performance of marine species will be impacted. Many studies have focused on how warming will impact physiology, life history, and behavior, but few studies have investigated how ecological and behavioral traits of organisms will affect their response to changing thermal environments. Here, we assessed the thermal tolerances and thermal sensitivity of swimming performance of two sympatric mysid shrimp species of the Northwest Atlantic. Neomysis americana and Heteromysis formosa overlap in habitat and many aspects of their ecological niche, but only N. americana exhibits vertical migration. In temperate coastal ecosystems, temperature stratification of the water column exposes vertical migrators to a wider range of temperatures on a daily basis. We found that N. americana had a significantly lower critical thermal minimum (CT min ) and critical thermal maximum (CT max ). However, both mysid species had a buffer of at least 4°C between their CT max and the 100-year projection for mean summer water temperatures of 28°C. Swimming performance of the vertically migrating species was more sensitive to temperature variation, and this species exhibited faster burst swimming speeds. The generalist performance curve of H. formosa and specialist curve of N. americana are consistent with predictions based on the exposure of each species to temperature variation such that higher within-generation variability promotes specialization. However, these species violate the assumption of the specialist-generalist tradeoff in that the area under their performance curves is not constant. Our results highlight the importance of incorporating species-specific responses to temperature based on the ecology and behavior of organisms into climate change prediction models. Copyright © 2016. Published by Elsevier Ltd.

Apparatus for magnetic separation of paramagnetic and diamagnetic material

DOEpatents

Doctor, Richard D.

1988-01-01

The present invention relates to methods and apparatus for segregating paramagnetic from diamagnetic particles in particulate material and, in particular, to the open gradient magnetic separation of ash producing components and pyritic sulfur from coal. The apparatus includes a vertical cylinder and a rotatable vertical screw positioned within the cylinder, the screw having a helical blade angled downwardly and outwardly from the axis. Rotation of the vertical screw causes denser particles, which in the case of coal include pyritic sulfur and ash, which are paramagnetic, to migrate to the outside of the screw, and less dense particles, such as the low sulfur organic portion of the coal, which are diamagnetic, to migrate towards the center of the screw. A vibration mechanism attached to the screw causes the screw to vibrate during rotation, agitating and thereby accommodating further segregation of the particles. An open gradient magnetic field is applied circumferentially along the entire length of the screw by a superconducting quadropole magnet. The open gradient magnetic field further segregates the paramagnetic particles from the diamagnetic particles. The paramagnetic particles may then be directed from the cylinder into a first storage bin, and the diamagnetic particles, which are suitable for relatively clean combustion, may be directed into a second storage bin.

Apparatus for magnetic separation of paramagnetic and diamagnetic material

DOEpatents

Doctor, R.D.

1988-10-18

The present invention relates to methods and apparatus for segregating paramagnetic from diamagnetic particles in particulate material and, in particular, to the open gradient magnetic separation of ash producing components and pyritic sulfur from coal. The apparatus includes a vertical cylinder and a rotatable vertical screw positioned within the cylinder, the screw having a helical blade angled downwardly and outwardly from the axis. Rotation of the vertical screw causes denser particles, which in the case of coal include pyritic sulfur and ash, which are paramagnetic, to migrate to the outside of the screw, and less dense particles, such as the low sulfur organic portion of the coal, which are diamagnetic, to migrate towards the center of the screw. A vibration mechanism attached to the screw causes the screw to vibrate during rotation, agitating and thereby accommodating further segregation of the particles. An open gradient magnetic field is applied circumferentially along the entire length of the screw by a superconducting quadrupole magnet. The open gradient magnetic field further segregates the paramagnetic particles from the diamagnetic particles. The paramagnetic particles may then be directed from the cylinder into a first storage bin, and the diamagnetic particles, which are suitable for relatively clean combustion, may be directed into a second storage bin. 5 figs.

Apparatus for magnetic separation of paramagnetic and diamagnetic material

DOEpatents

Doctor, R.D.

1986-07-24

The present invention relates to methods and apparatus for segregating paramagnetic from diamagnetic particles in particulate material and, in particular, to the open gradient magnetic separation of ash producing components and pyritic sulfur from coal. The apparatus includes a vertical cylinder and a rotatable vertical screw positioned within the cylinder, the screw having a helical blade angled downwardly and outwardly from the axis. Rotation of the vertical screw causes denser particles, which in the case of coal include pyritic sulfur and ash, which are paramagnetic, to migrate to the outside of the screw, and less dense particles, such as the low sulfur organic portion of the coal, which are diamagnetic, to migrate towards the center of the screw. A vibration mechanism attached to the screw causes the screw to vibrate during rotation, agitating and thereby accommodating further segregation of the particles. An open gradient magnetic field is applied circumferentially along the entire length of the screw by a superconducting quadrupole magnet. The open gradient magnetic field further segregates the paramagnetic-particles from the diamagnetic particles. The paramagnetic particles may then be directed from the cylinder into a first storage bin, and the diamagnetic particles, which are suitable for relatively clean combustion, may be directed into a second storage bin. 5 figs.

Lipid Class, Carotenoid, and Toxin Dynamics of Karenia Brevis (Dinophyceae) During Diel Vertical Migration

EPA Science Inventory

Karenia brevis’ (Hansen and Moestrup) internal lipid, carotenoid, and toxin concentrations are influenced by its ability to use ambient light and nutrients for growth and reproduction. This project investigated changes of K. brevis toxicity, lipid class and carotenoid concentrat...

Environmental Influences on Diel Calling Behavior in Baleen Whales

DTIC Science & Technology

2012-09-30

small copepods (e.g., Oithona spp.) to large euphausiids (e.g., Meganyctiphanes norvegica). Sampling will occur during both day and night to assess...vocalization rates and the vertical migration of their copepod prey observed from ocean gliders. Limnology and Oceanography 53:2197-2209

Do swimming animals mix the ocean?

NASA Astrophysics Data System (ADS)

Dabiri, John

2013-11-01

Perhaps. The oceans are teeming with billions of swimming organisms, from bacteria to blue whales. Current research efforts in biological oceanography typically focus on the impact of the marine environment on the organisms within. We ask the opposite question: can organisms in the ocean, especially those that migrate vertically every day and regionally every year, change the physical structure of the water column? The answer has potentially important implications for ecological models at local scale and climate modeling at global scales. This talk will introduce the still-controversial prospect of biogenic ocean mixing, beginning with evidence from measurements in the field. More recent laboratory-scale experiments, in which we create controlled vertical migrations of plankton aggregations using laser signaling, provide initial clues toward a mechanism to achieve efficient mixing at scales larger than the individual organisms. These results are compared and contrasted with theoretical models, and they highlight promising avenues for future research in this area. Funding from the Office of Naval Research and the National Science Foundation is gratefully acknowledged.

Diel horizontal migration in streams: juvenile fish exploit spatial heterogeneity in thermal and trophic resources

USGS Publications Warehouse

Armstrong, Jonathan B.; Schindler, Daniel E.; Ruff, Casey P.; Brooks, Gabriel T.; Bentley, Kale E.; Torgersen, Christian E.

2013-01-01

Vertical heterogeneity in the physical characteristics of lakes and oceans is ecologically salient and exploited by a wide range of taxa through diel vertical migration to enhance their growth and survival. Whether analogous behaviors exploit horizontal habitat heterogeneity in streams is largely unknown. We investigated fish movement behavior at daily timescales to explore how individuals integrated across spatial variation in food abundance and water temperature. Juvenile coho salmon made feeding forays into cold habitats with abundant food, and then moved long distances (350–1300 m) to warmer habitats that accelerated their metabolism and increased their assimilative capacity. This behavioral thermoregulation enabled fish to mitigate trade-offs between trophic and thermal resources by exploiting thermal heterogeneity. Fish that exploited thermal heterogeneity grew at substantially faster rates than did individuals that assumed other behaviors. Our results provide empirical support for the importance of thermal diversity in lotic systems, and emphasize the importance of considering interactions between animal behavior and habitat heterogeneity when managing and restoring ecosystems.

COLD TRAP

DOEpatents

Milleron, N.

1963-03-12

An improved linear-flow cold trap is designed for highvacuum applications such as mitigating back migration of diffusion pump oil moiecules. A central pot of liquid nitrogen is nested within and supported by a surrounding, vertical, helical coil of metai sheet, all enveloped by a larger, upright, cylindrical, vacuum vessel. The vertical interstices between successive turns of the coil afford lineal, axial, high-vacuum passages between open mouths at top and bottom of said vessel, while the coil, being cold by virtue of thermal contact of its innermost turn with the nitrogen pot, affords expansive proximate condensation surfaces. (AEC)

Empirical observations of the spawning migration of European eels: The long and dangerous road to the Sargasso Sea.

PubMed

Righton, David; Westerberg, Håkan; Feunteun, Eric; Økland, Finn; Gargan, Patrick; Amilhat, Elsa; Metcalfe, Julian; Lobon-Cervia, Javier; Sjöberg, Niklas; Simon, Janek; Acou, Anthony; Vedor, Marisa; Walker, Alan; Trancart, Thomas; Brämick, Uwe; Aarestrup, Kim

2016-10-01

The spawning migration of the European eel ( Anguilla anguilla L.) to the Sargasso Sea is one of the greatest animal migrations. However, the duration and route of the migration remain uncertain. Using fishery data from 20 rivers across Europe, we show that most eels begin their oceanic migration between August and December. We used electronic tagging techniques to map the oceanic migration from eels released from four regions in Europe. Of 707 eels tagged, we received 206 data sets. Many migrations ended soon after release because of predation events, but we were able to reconstruct in detail the migration routes of >80 eels. The route extended from western mainland Europe to the Azores region, more than 5000 km toward the Sargasso Sea. All eels exhibited diel vertical migrations, moving from deeper water during the day into shallower water at night. The range of migration speeds was 3 to 47 km day -1 . Using data from larval surveys in the Sargasso Sea, we show that spawning likely begins in December and peaks in February. Synthesizing these results, we show that the timing of autumn escapement and the rate of migration are inconsistent with the century-long held assumption that eels spawn as a single reproductive cohort in the springtime following their escapement. Instead, we suggest that European eels adopt a mixed migratory strategy, with some individuals able to achieve a rapid migration, whereas others arrive only in time for the following spawning season. Our results have consequences for eel management.

Migration Pathways, Behavioural Thermoregulation and Overwintering Grounds of Blue Sharks in the Northwest Atlantic

PubMed Central

Campana, Steven E.; Dorey, Anna; Fowler, Mark; Joyce, Warren; Wang, Zeliang; Yashayaev, Igor

2011-01-01

The blue shark Prionace glauca is the most abundant large pelagic shark in the Atlantic Ocean. Although recaptures of tagged sharks have shown that the species is highly migratory, migration pathways towards the overwintering grounds remain poorly understood. We used archival satellite pop-up tags to track 23 blue sharks over a mean period of 88 days as they departed the coastal waters of North America in the autumn. Within 1–2 days of entering the Gulf Stream (median date of 21 Oct), all sharks initiated a striking diel vertical migration, taking them from a mean nighttime depth of 74 m to a mean depth of 412 m during the day as they appeared to pursue vertically migrating squid and fish prey. Although functionally blind at depth, calculations suggest that there would be a ∼2.5-fold thermoregulatory advantage to swimming and feeding in the markedly cooler deep waters, even if there was any reduced foraging success associated with the extreme depth. Noting that the Gulf Stream current speeds are reduced at depth, we used a detailed circulation model of the North Atlantic to examine the influence of the diving behaviour on the advection experienced by the sharks. However, there was no indication that the shark diving resulted in a significant modification of their net migratory pathway. The relative abundance of deep-diving sharks, swordfish, and sperm whales in the Gulf Stream and adjacent waters suggests that it may serve as a key winter feeding ground for large pelagic predators in the North Atlantic. PMID:21373198

Response of a veterinary college to career development needs identified in the KPMG LLP study and the executive summary of the Brakke study: a combined MBA/DVM program, business certificate program, and curricular modifications.

PubMed

Kogan, Lori R; McConnell, Sherry L; Schoenfeld-Tacher, Regina

2005-04-01

In the present market, veterinarians with a strong background in career development, practice management, and business skills have a clear advantage in achieving financial success. Although there is ample evidence that the scientific and clinical skills of veterinary college graduates are high, there are also data that suggest that additional capabilities in the business realm may promote greater economic success. As noted in the KPMG executive summary, the field of veterinary medicine must make changes in its "current business practices and attitudes" to be successful in the future. Furthermore, the KPMG study found that 36% of industry employers reported that some jobs within their companies had specific job requirements that were not met by a veterinarian with only a veterinary medical degree. The areas of additional training most often cited included business, administration, personnel management, sales and marketing, and financial skills. Yet, Lewis and Klausner found that veterinarians reported challenges in the business realm, such as "how business works and how business goals are translated into action. This challenge held true for veterinarians in industry, academia, government, and private practice." The present gender trends in the field of veterinary medicine provide additional impetus to make career development and business skills training more prevalent. Presently, women comprise >65% of the veterinary student population and approximately 45% of all practicing veterinarians. In some areas of practice, the rate is much higher. For example, in 2002, women comprised 48.2% of all small animal exclusive private practitioners. Unfortunately, the KPMG study found that female veterinarians in private practice report lower self-evaluation of business management and financial skills, compared with their male cohorts. Female veterinarians in nonprivate practice report lower self-evaluation in communication, personnel management, business management, and marketing skills than that reported by males. As a result of these pressing needs, CSU CVMBS has undertaken a major initiative to improve the veterinary practice management and business skills training of veterinary students by offering a variety of options to gain this knowledge: a combined MBA/DVM degree program, a Business Certificate Program for Health Professions, and core curriculum courses. In this way, students can select the amount of focus they want to place on career development and business skills as they earn their DVM degree, to best ensure that they become successful veterinarians.

A Pseudo-Vertical Equilibrium Model for Slow Gravity Drainage Dynamics

NASA Astrophysics Data System (ADS)

Becker, Beatrix; Guo, Bo; Bandilla, Karl; Celia, Michael A.; Flemisch, Bernd; Helmig, Rainer

2017-12-01

Vertical equilibrium (VE) models are computationally efficient and have been widely used for modeling fluid migration in the subsurface. However, they rely on the assumption of instant gravity segregation of the two fluid phases which may not be valid especially for systems that have very slow drainage at low wetting phase saturations. In these cases, the time scale for the wetting phase to reach vertical equilibrium can be several orders of magnitude larger than the time scale of interest, rendering conventional VE models unsuitable. Here we present a pseudo-VE model that relaxes the assumption of instant segregation of the two fluid phases by applying a pseudo-residual saturation inside the plume of the injected fluid that declines over time due to slow vertical drainage. This pseudo-VE model is cast in a multiscale framework for vertically integrated models with the vertical drainage solved as a fine-scale problem. Two types of fine-scale models are developed for the vertical drainage, which lead to two pseudo-VE models. Comparisons with a conventional VE model and a full multidimensional model show that the pseudo-VE models have much wider applicability than the conventional VE model while maintaining the computational benefit of the conventional VE model.

EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011: Well Integrity Case Study by Lloyd H. Hetrick

EPA Pesticide Factsheets

This case study defines well integrity by the prevention of vertical migration of fluids to protect drinking water resources. A generic shale development well is presented, including design, construction, operational phase, and its plug and abandonment.

Assessment of the effects of regional channel stability and sediment transport on roadway hydraulic structures : final report.

DOT National Transportation Integrated Search

2014-06-01

Rivers and streams evolve all the time. As a result, no stream channel is absolutely stable. Channels evolve at various speeds both vertically (degradation/aggradation) and horizontally (meander : migration). They also respond to man-made changes ran...

Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

NASA Astrophysics Data System (ADS)

Liu, H.; Richmond, A. D.

2013-12-01

In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

Partial diel migration: A facultative migration underpinned by long-term inter-individual variation.

PubMed

Harrison, Philip M; Gutowsky, Lee F G; Martins, Eduardo G; Patterson, David A; Cooke, Steven J; Power, Michael

2017-09-01

The variations in migration that comprise partial diel migrations, putatively occur entirely as a consequence of behavioural flexibility. However, seasonal partial migrations are increasingly recognised to be mediated by a combination of reversible plasticity in response to environmental variation and individual variation due to genetic and environmental effects. Here, we test the hypothesis that while partial diel migration heterogeneity occurs primarily due to short-term within-individual flexibility in behaviour, long-term individual differences in migratory behaviour also underpin this migration variation. Specifically, we use a hierarchical behavioural reaction norm approach to partition within- and among-individual variation in depth use and diel plasticity in depth use, across short- and long-term time-scales, in a group of 47 burbot (Lota lota) tagged with depth-sensing acoustic telemetry transmitters. We found that within-individual variation at the among-dates-within-seasons and among-seasons scale, explained the dominant proportion of phenotypic variation. However, individuals also repeatedly differed in their expression of migration behaviour over the 2 year study duration. These results reveal that diel migration variation occurs primarily due to short-term within-individual flexibility in depth use and diel migration behaviour. However, repeatable individual differences also played a key role in mediating partial diel migration. These findings represent a significant advancement of our understanding of the mechanisms generating the important, yet poorly understood phenomena of partial diel migration. Moreover, given the pervasive occurrence of diel migrations across aquatic taxa, these findings indicate that individual differences have an important, yet previously unacknowledged role in structuring the temporal and vertical dynamics of aquatic ecosystems. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Seismic imaging of the Waltham Canyon fault, California: comparison of ray‐theoretical and Fresnel volume prestack depth migration

USGS Publications Warehouse

Bauer, Klaus; Ryberg, Trond; Fuis, Gary S.; Lüth, Stefan

2013-01-01

Near‐vertical faults can be imaged using reflected refractions identified in controlled‐source seismic data. Often theses phases are observed on a few neighboring shot or receiver gathers, resulting in a low‐fold data set. Imaging can be carried out with Kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data. Fresnel volume migration can be used for low‐fold data without severe migration noise, as the smearing along isochrones is limited to the first Fresnel zone around the reflection point. We developed a modified Fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases. The modifications include target‐oriented filters to separate reflected refractions from steep‐dipping faults and reflections with hyperbolic moveout. Undesired phases like multiple reflections, mode conversions, direct P and S waves, and surface waves are suppressed by these filters. As an alternative approach, we developed a new prestack line‐drawing migration method, which can be considered as a proxy to an infinite frequency approximation of the Fresnel volume migration. The line‐drawing migration is not considering waveform information but requires significantly shorter computational time. Target‐oriented filters were extended by dip filters in the line‐drawing migration method. The migration methods were tested with synthetic data and applied to real data from the Waltham Canyon fault, California. The two techniques are applied best in combination, to design filters and to generate complementary images of steep faults.

Experimental Research on Thermocapillary-Buoyancy Migration Interaction of Axisymmetric Two Drops by Using Digital Holographic Interferometry

NASA Astrophysics Data System (ADS)

Zhang, Shuoting; Duan, Li; Kang, Qi

2018-05-01

The migration and interaction of axisymmetric two drops in a vertical temperature gradient is investigated experimentally on the ground. A silicon oil is used as the continuous phase, and a water-ethanol mixture is used as the drop phase, respectively. The migration and interaction of two drops, under the combined effects of buoyancy and thermocapillary, is recorded by a digital holographic interferometry measurement in the experiment to analyse the velocities and temperature distribution of the drops. As a result, when two drops migrate together, the drop affects the other drop by perturbing the temperature field around itself. For the leading drop, the velocity is faster than the one of the isolated drop, and the maximum of the interfacial temperature distribution is larger than the one of the isolated drop. For the trailing drop, the velocity is slower than the one of the isolated drop, and the maximum of the interfacial temperature distribution is less than the one of the isolated drop. The influence of the dimensionless initial distance between the drop centres to the drop migration is discussed in detail in this study.

Tracking Topographic Changes from Multitemporal Stereo Images, Application to the Nili Patera Dune Field

NASA Astrophysics Data System (ADS)

Avouac, J.; Ayoub, F.; Bridges, N. T.; Leprince, S.; Lucas, A.

2012-12-01

The High Resolution Imaging Science Experiment (HiRISE) in orbit around Mars provides images with a nominal ground resolution of 25cm. Its agility allows imaging a same scene with stereo view angles thus allowing for for Digital elevation Model (DEM) extraction through stereo-photogrammetry. This dataset thus offers an exceptional opportunity to measure the topography with high precision and track its eventual evolution with time. In this presentation, we will discuss how multi-temporal acquisitions of HiRISE images of the Nili Patera dune field allow tracking ripples migration, assess sand fluxes and dunes activity. We investigated in particular the use of multi-temporal DEMs to monitor the migration and morphologic evolution of the dune field. We present here the methodology used and the various challenges that must be overcome to best exploit the multi-temporal images. Two DEMs were extracted from two stereo images pairs acquired 390 earth days apart in 2010-2011 using SOCET SET photogrammetry software, with a 1m post-spacing and a vertical accuracy of few tens of centimeters. Prior to comparison the DEMs registration, which was not precise enough out of SOCET-SET, was improved by wrapping the second DEM onto the first one using the bedrock only as a support for registration. The vertical registration residual was estimated at around 40cm RMSE and is mostly due to CCD misalignment and uncorrected spacecraft attitudes. Changes of elevation over time are usually determined from DEMs differentiation: provided that DEMs are perfectly registered and sampled on the same grid, this approach readily quantifies erosion and deposition processes. As the dunes have moved horizontally, they are not physically aligned anymore in the DEMs, and their morphologic evolution cannot be recovered easily from differentiating the DEMs. In this particular setting the topographic evolution is best recovered from correlation of the DEMs. We measure that the fastest dunes have migrated by up to 1meter per Earth year as a result of lee front deposition and stoss slope erosion. DEMs differentiation, after correction for horizontal migration, provides and additional information on dune morphology evolution. Some dunes show a vertical growth over the 390 days spanning the 2 DEMs, but we cannot exclude a bias due to the acquisition parameters. Indeed, the images of the two stereo pairs were acquired 22 and 5 days apart, respectively. During that time, the ripples laying on the dune surface have probably migrated. As the DEMs extraction is based on feature tracking and parallax, this difference in DEMs elevation may be only, or in part, due to the ripple migration between the acquisition times that biased the actual dune elevations.

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas.

PubMed

Villareal, Tracy A; Pilskaln, Cynthia H; Montoya, Joseph P; Dennett, Mark

2014-01-01

In oceanic subtropical gyres, primary producers are numerically dominated by small (1-5 µm diameter) pro- and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen (N) to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and N2-fixation. This input of new N to balance export losses (the biological pump) is a fundamental aspect of N cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed N budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80-100 m) into the surface layer (∼0-40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown. In these seas, vertical migration by the very largest (10(2)-10(3) µm diameter) phytoplankton is common as a survival strategy to obtain N from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward N transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to show that migrating diatom (Rhizosolenia) mats are widespread in the N. Pacific Ocean from 140°W to 175°E and together with other migrating phytoplankton (Ethmodiscus, Halosphaera, Pyrocystis, and solitary Rhizosolenia) can mediate time-averaged transport of N (235 µmol N m(-2) d(-1)) equivalent to eddy nitrate injections (242 µmol NO3 (-) m(-2) d(-1)). This upward biotic transport can close N budgets in the upper 250 m of the central Pacific Ocean and together with diazotrophy creates a surface zone where biological nutrient inputs rather than physical processes dominate the new N flux. In addition to these numerically rare large migrators, there is evidence in the literature of ascending behavior in small phytoplankton that could contribute to upward flux as well. Although passive downward movement has dominated models of phytoplankton flux, there is now sufficient evidence to require a rethinking of this paradigm. Quantifying these fluxes is a challenge for the future and requires a reexamination of individual phytoplankton sinking rates as well as methods for capturing and enumerating ascending phytoplankton in the sea.

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

PubMed Central

Pilskaln, Cynthia H.; Montoya, Joseph P.; Dennett, Mark

2014-01-01

In oceanic subtropical gyres, primary producers are numerically dominated by small (1–5 µm diameter) pro- and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen (N) to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and N2-fixation. This input of new N to balance export losses (the biological pump) is a fundamental aspect of N cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed N budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80–100 m) into the surface layer (∼0–40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown. In these seas, vertical migration by the very largest (102–103 µm diameter) phytoplankton is common as a survival strategy to obtain N from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward N transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to show that migrating diatom (Rhizosolenia) mats are widespread in the N. Pacific Ocean from 140°W to 175°E and together with other migrating phytoplankton (Ethmodiscus, Halosphaera, Pyrocystis, and solitary Rhizosolenia) can mediate time-averaged transport of N (235 µmol N m-2 d-1) equivalent to eddy nitrate injections (242 µmol NO3− m-2 d-1). This upward biotic transport can close N budgets in the upper 250 m of the central Pacific Ocean and together with diazotrophy creates a surface zone where biological nutrient inputs rather than physical processes dominate the new N flux. In addition to these numerically rare large migrators, there is evidence in the literature of ascending behavior in small phytoplankton that could contribute to upward flux as well. Although passive downward movement has dominated models of phytoplankton flux, there is now sufficient evidence to require a rethinking of this paradigm. Quantifying these fluxes is a challenge for the future and requires a reexamination of individual phytoplankton sinking rates as well as methods for capturing and enumerating ascending phytoplankton in the sea. PMID:24688877

Sub-slab vs. Near-slab Soil Vapor Profiles at a Chlorinated Solvent Site

EPA Science Inventory

A critical issue in assessing the vapor intrusion pathway is the distribution and migration of VOCs from the subsurface source to the near surface environment. Therefore, EPA/ORD funded a research project with the primary goal of comparing vertical profiles of soil gas concentrat...

Boundary shear stress along rigid trapezoidal bends

Treesearch

Christopher I. Thornton; Kyung-Seop Sin; Paul Sclafani; Steven R. Abt

2012-01-01

The migration of alluvial channels through the geologic landform is an outcome of the natural erosive processes. Mankind continually attempts to stabilize channel meandering processes, both vertically and horizontally, to reduce sediment discharge, provide boundary definition, and enable economic development along the river's edge. A critical component in the...

Primary Dermal Irritation Potential of Components of the M-258A-1 Decontamination Kit (Study 3).

DTIC Science & Technology

1981-09-01

PROJECT: Medical Defense Against Chemical Agents 612772.875. GLP STUDY NUMBER: 81019 STUDY DIRECTOR: LTC (P) John T. Fruin, DVM, PhD, VC, Diplomate...hereby certify that in relation to LAIR GLP study 81019 the following inspections were made: 11 June 1981 15 June 1981 16 June 1981 18 June 1981...gryI___________- APPENDIX A-3 Suiu:c ria of Prir-ary SkiT: Irritation Test Data GLP St Jv No. 81019 Chemica1 ;lanme Conr Solvent :Amt AoI ied Date of

Lateral and vertical distribution of downstream migrating juvenile sea lamprey

USGS Publications Warehouse

Sotola, V. Alex; Miehls, Scott M.; Simard, Lee G.; Marsden, J. Ellen

2018-01-01

Sea lamprey is considered an invasive and nuisance species in the Laurentian Great Lakes, Lake Champlain, and the Finger Lakes of New York and is a major focus of control efforts. Currently, management practices focus on limiting the area of infestation using barriers to block migratory adults, and lampricides to kill ammocoetes in infested tributaries. No control efforts currently target the downstream-migrating post-metamorphic life stage which could provide another management opportunity. In order to apply control methods to this life stage, a better understanding of their downstream movement patterns is needed. To quantify spatial distribution of downstream migrants, we deployed fyke and drift nets laterally and vertically across the stream channel in two tributaries of Lake Champlain. Sea lamprey was not randomly distributed across the stream width and lateral distribution showed a significant association with discharge. Results indicated that juvenile sea lamprey is most likely to be present in the thalweg and at midwater depths of the stream channel. Further, a majority of the catch occurred during high flow events, suggesting an increase in downstream movement activity when water levels are higher than base flow. Discharge and flow are strong predictors of the distribution of out-migrating sea lamprey, thus managers will need to either target capture efforts in high discharge areas of streams or develop means to guide sea lamprey away from these areas.

Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Bin; Li, Huiying; Du, Xiaoming

2016-02-01

During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significantmore » positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.« less

Feasibility of the Scalable, Automated, Semipermanent Seismic Array (SASSA) to Monitor Possible Carbon Dioxide Migration

NASA Astrophysics Data System (ADS)

Livers, A. J.; Burnison, S. A.; Salako, O.; Barajas-Olalde, C.; Hamling, J. A.; Gorecki, C. D.

2016-12-01

The feasibility of monitoring potential carbon dioxide (CO2) migration in a reservoir using a sparse seismic array is being evaluated by the Energy & Environmental Research Center (EERC) at the Denbury Onshore LLC-operated Bell Creek oil field in Montana, which is undergoing commercial CO2 enhanced oil recovery (EOR). This new method may provide an economical means of continuously monitoring the CO2 plume edge and the CO2 reservoir boundaries and/or to interpret vertical or lateral out-of-reservoir CO2 migration. A 96-station scalable, automated, semipermanent seismic array (SASSA) was deployed in October 2015 to detect and track CO2 plume migration not by imaging, but by monitoring discrete source-receiver midpoints. Midpoints were strategically located within and around four injector-producer patterns covering approximately one square mile. Three-dimensional (3-D) geophysical ray tracing was used to determine surface receiver locations. Receivers used were FairfieldNodal Zland three-component, autonomous, battery-powered nodes. A GISCO ESS850 accelerated weight drop source located in a secure structure was remotely fired on a weekly basis for one calendar year, including a two-month period prior to initiation of CO2 injection to establish a baseline. Fifty shots were fired one day each week to facilitate increased signal-to-noise through novel receiver domain processing and vertical stacking. Receiver domain processing allowed for individualization of processing parameters to maximize signal enhancement and noise attenuation. Reflection events in the processed SASSA data correlate well to 3-D surface survey data collected in the field. Preliminary time-lapse data results for several individual SASSA receivers show a phase shift in the reflection events below the reservoir after injection, suggesting possible migration of the CO2 in the reservoir to the corresponding midpoint locations. This work is supported by the U.S. Department of Energy National Energy Technology Laboratory under Award No. FE0012665.

The Comparison Study of gas source between two hydrate expeditions in ShenHu area, SCS

NASA Astrophysics Data System (ADS)

Cong, X. R.

2016-12-01

Two gas hydrate expeditions (GMGS 01&03) were conducted in the Pearl River Mouth Basin, SCS, which were organized by Guangzhou Marine Geological Survey in 2007 and 2015, respectively. Compared with the drilling results of "mixed bio-thermogenic gas and generally dominated by biogenic gas" in 2007, hydrocarbon component measurements revealed a higher content of ethane and propane in 2015 drilling, providing direct evidence that deep thermogenic gas was the source for shallow hydrate formation. According to the geochemical analyses of the results obtained from the industrial boreholes in Baiyun sag, the deep hydrocarbon gas obviously leaked from the reservoir as escape caused by Dongsha movement in the late Miocene, as a result thermogenic gas from Wenchang, Enping and Zhuhai hydrocarbon source rocks migrated to late Miocene shallow strata through faults, diapirs and gas chimney vertically migration. In this paper we report the differences in fluid migration channel types and discuss their effect in fluid vertical migration efficiency in the two Shenhu hydrate drilling areas. For the drilling area in 2007,when the limited deep thermogenic gas experienced long distance migration process from bottom to up along inefficient energy channel, the gas composition might have changed and the carbon isotope fractionation might have happened, which were reflected in the results of higher C1/C2 ratios and lighter carbon isotope in gas hydrate bearing sediments. As a result the gas is with more "biogenic gas" features. It means thermogenic gases in the deep to contributed the formation of shallow gas hydrate indirectly in 2007 Shenhu drill area. On another hand, the gases were transported to the shallow sediment layers efficiently, where gas hydrate formed, through faults and fractures from deep hydrocarbon reservoirs, and as the result they experienced less changes in both components and isotopes in 2015 drilling site.

LONG-TERM DYNAMICS OF RADIONUCLIDE VERTICAL MIGRATION IN SOILS OF THE CHERNOBYL NUCLEAR POWER PLANT EXCLUSION ZONE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farfan, E

2009-11-19

The radioactive fallout from the Chernobyl Nuclear Power Plant (ChNPP) accident consisted of fuel and condensation components. An important radioecological task associated with the late phase of the accident is to evaluate the dynamics of radionuclide mobility in soils. Identification of the variability (or invariability) in the radionuclide transfer parameters makes it possible to (1) accurately predict migration patterns and biological availability of radionuclides and (2) evaluate long-term exposure trends for the population who may reoccupy the remediated abandoned areas. In 1986-1987, a number of experimental plots were established within various tracts of the fallout plume to assist with themore » determination of the long-term dynamics of radionuclide vertical migration in the soils. The transfer parameters for {sup 137}Cs, {sup 90}Sr, and {sup 239,240}Pu in the soil profile, as well as their ecological half-time of the radionuclide residence (T{sub 1/2}{sup ecol}) values in the upper 5-cm thick soil layers of different grasslands were estimated at various times since the accident. Migration characteristics in the grassland soils tend to decrease as follows: {sup 90}Sr > {sup 137}Cs {ge} {sup 239,240}Pu. It was found that the {sup 137}Cs absolute T{sub 1/2}{sup ecol} values are 3-7 times higher than its radioactive decay half-life value. Therefore, changes in the exposure dose resulting from the soil deposited {sup 137}Cs now depend only on its radioactive decay. The {sup 90}Sr T{sub 1/2}{sup ecol} values for the 21st year after the fallout tend to decrease, indicating an intensification of its migration capabilities. This trend appears consistent with a pool of mobile {sup 90}Sr forms that grows over time due to destruction of the fuel particles.« less

Modelling larval transport in a axial convergence front

NASA Astrophysics Data System (ADS)

Robins, P.

2010-12-01

Marine larvae exhibit different vertical swimming behaviours, synchronised by factors such as tidal currents and daylight, in order to aid retention near the parent populations and hence promote production, avoid predation, or to stimulate digestion. This paper explores two types of larval migration in an estuarine axial convergent front which is an important circulatory mechanism in many coastal regions where larvae are concentrated. A parallelised, three-dimensional, ocean model was applied to an idealised estuarine channel which was parameterised from observations of an axial convergent front which occurs in the Conwy Estuary, U.K. (Nunes and Simpson, 1985). The model successfully simulates the bilateral cross-sectional recirculation of an axial convergent front, which has been attributed to lateral density gradients established by the interaction of the lateral shear of the longitudinal currents with the axial salinity gradients. On the flood tide, there is surface axial convergence whereas on the ebb tide, there is (weaker) surface divergence. Further simulations with increased/decreased tidal velocities and with stronger/weaker axial salinity gradients are planned so that the effects of a changing climate on the secondary flow can be understood. Three-dimensional Lagrangian Particle Tracking Models (PTMs) have been developed which use the simulated velocity fields to track larvae in the estuarine channel. The PTMs take into account the vertical migrations of two shellfish species that are commonly found in the Conwy Estuary: (i) tidal migration of the common shore crab (Carcinus maenas) and (ii), diel (daily) migration of the Great scallop (Pecten maximus). These migration behaviours are perhaps the most widespread amongst shellfish larvae and have been compared with passive (drifting) particles in order to assess their relative importance in terms of larval transport. Preliminary results suggest that the net along-estuary dispersal over a typical larval period of 28 days of both passive and daily synchronised larvae will follow the asymmetry of the tide (i.e. for a symmetrical tide, the net dispersal is likely to be zero). For tidally synchronised larvae, there is an up-estuary migration as the larvae swim upwards to the stronger surface currents during the flood tide.

Multi-parameter Full-waveform Inversion for Acoustic VTI Medium with Surface Seismic Data

NASA Astrophysics Data System (ADS)

Cheng, X.; Jiao, K.; Sun, D.; Huang, W.; Vigh, D.

2013-12-01

Full-waveform Inversion (FWI) attracts wide attention recently in oil and gas industry as a new promising tool for high resolution subsurface velocity model building. While the traditional common image point gather based tomography method aims to focus post-migrated data in depth domain, FWI aims to directly fit the observed seismic waveform in either time or frequency domain. The inversion is performed iteratively by updating the velocity fields to reduce the difference between the observed and the simulated data. It has been shown the inversion is very sensitive to the starting velocity fields, and data with long offsets and low frequencies is crucial for the success of FWI to overcome this sensitivity. Considering the importance of data with long offsets and low frequencies, in most geologic environment, anisotropy is an unavoidable topic for FWI especially at long offsets, since anisotropy tends to have more pronounced effects on waves traveled for a great distance. In VTI medium, this means more horizontal velocity will be registered in middle-to-long offset data, while more vertical velocity will be registered in near-to-middle offset data. Up to date, most of real world applications of FWI still remain in isotropic medium, and only a few studies have been shown to account for anisotropy. And most of those studies only account for anisotropy in waveform simulation, but not invert for those anisotropy fields. Multi-parameter inversion for anisotropy fields, even in VTI medium, remains as a hot topic in the field. In this study, we develop a strategy for multi-parameter FWI for acoustic VTI medium with surface seismic data. Because surface seismic data is insensitivity to the delta fields, we decide to hold the delta fields unchanged during our inversion, and invert only for vertical velocity and epsilon fields. Through parameterization analysis and synthetic tests, we find that it is more feasible to invert for the parameterization as vertical and horizontal velocities instead of inverting for the parameterization as vertical velocity and epsilon fields. We develop a hierarchical approach to invert for vertical velocity first but hold epsilon unchanged and only switch to simultaneous inversion when vertical velocity inversion are approaching convergence. During simultaneous inversion, we observe significant acceleration in the convergence when incorporates second order information and preconditioning into inversion. We demonstrate the success of our strategy for VTI FWI using synthetic and real data examples from the Gulf of Mexico. Our results show that incorporation of VTI FWI improves migration of large offset acquisition data, and produces better focused migration images to be used in exploration, production and development of oil fields.

Vertical distribution and daily migrations of hyperiid amphipods in the northern Benguela in relation to water column stratification

NASA Astrophysics Data System (ADS)

Cornet, Carme; Gili, Josep-Maria

1993-11-01

The vertical distribution and migratory behaviour of hyperiid amphipods were studied in a series of tows carried out during a 48-h sampling period at an oceanic station at the northern edge of the Benguela System during a major penetration by Angola Current waters. A total of 49 species of hyperiid amphipods were collected; of these, Tetrathyrus forcipatus was the most abundant, with densities greater than two individuals per 10 m 3. Vibilia armata, Lestrigonus latissimus, L. bengalensis and Paratyphis promontorii were also highly abundant. During the sampling period most species were concentrated in the uppermost 40 m of the water column, though in other regions the vertical distribution of these same species has been reported to be broader. Only a few species were able to migrate through the thermocline. We hypothesize that both the non-migratory behaviour and the aggregation of individuals and species were caused by two primary factors: the existence of a strong thermocline, which hindered the transit of species to deeper layers, and abundant concentrations of gelatinous zooplankton above the thermocline. Hyperiids and the gelatinous zooplankton, particularly medusae and siphonophores, exhibited a close association during the sampling period, suggesting that hyperiids are able to partition their habitat by using the different medusan and siphonophoran species as specific substrates, thereby reducing interspecific competition.

Gas-controlled seafloor doming on Opouawe Bank, offshore New Zealand

NASA Astrophysics Data System (ADS)

Koch, Stephanie; Berndt, Christian; Bialas, Joerg; Haeckel, Matthias; Crutchley, Gareth; Papenberg, Cord; Klaeschen, Dirk; Greinert, Jens

2015-04-01

The process of gas accumulation and subsequent sediment doming appears to be a precursory process in the development of methane seep sites on Opouawe Bank and might be a common characteristic for gas seeps in general. Seabed domes appear as unimpressive topographic highs with diameters ranging from 10-1000 m and exhibit small vertical displacements and layer thickness in comparison to their width. The dome-like uplift of the sediments results from an increase in pore pressure caused by gas accumulation in near-seabed sediments. In this context sediment doming is widely discussed to be a precursor of pockmark formation. Our results suggest that by breaching of domed seafloor sediments a new seep site can develop and contrary to ongoing discussion does not necessarily lead to the formation of pockmarks. There are clear differences in individual gas migration structures that indicate a progression through different evolutionary stages, which range from channeled gas flow and associated seismic blanking, to gas trapping beneath relatively low-permeability horizons, and finally overpressure accumulation and doming. We present high resolution sub-bottom profiler (Parasound) and 2D multichannel seismic data from Opouawe Bank, an accretionary ridge at the Hikurangi Margin, offshore New Zealand's North Island. Beneath this bank, methane migrates along stratigraphic pathways from a maximum source depth of 1500-2100 mbsf (meter below seafloor) towards active cold seeps at the seafloor. We show that, in the shallow sediment of the upper 100 mbsf, this primary migration mechanism changes into a process of gas accumulation leading to sediment doming. Modeling the height of the gas column necessary to create different dome geometries, shows that doming due to gas accumulation is feasible and consistent with field observations. The well-stratified, sub-horizontal strata that exist beneath Opouawe Bank provide favorable conditions for this type of seep development because shallow sub-vertical gas migration is forced to traverse sedimentary layering in the absence of faults that might otherwise have provided more efficient gas migration pathways. Thus, gas has to generate its own migration pathways through the progressive process of doming and breaking through the strata. The data from offshore New Zealand document that shallow sediment doming does not have to be associated with seafloor pockmarks and that models in which fluid migration through soft sediments necessarily culminates in pockmark formations are not applicable everywhere.

Assessment of ground-water contamination near Lantana landfill, Southeast Florida

USGS Publications Warehouse

Russell, G.M.; Higer, A.L.

1988-01-01

The Lantana landfill located in Palm Beach County rises 40 to 50 feet above normal ground level and consists of about 250 acres of compacted garbage and trash, some below the water table. Surface-resistivity measurements and water-quality analyses indicate a contaminant plume along the eastern perimeter of the landfill that has migrated about 300 feet eastward toward an adjacent lake. Concentrations of chloride, ammonia, and nitrate were elevated within the plume. The surficial aquifer consists primarily of sand from 0 to about 68 feet, and sand interbedded with sandstone and limestone from 68 to 220 feet. A slight hydraulic gradient exists, indicating ground-water movement from the landfill toward a lake to the east. Analyses of geoelectric, lithologic, and water-quality data indicate that surface geophysical techniques were successful in determining the areal and vertical extent of leachate migration at this location.The Lantana landfill located in Palm Beach County rises 40 to 50 feet above normal ground level and consists of about 250 acres of compacted garbage and trash, some below the water table. Surface-resistivity measurements and water-quality analyses indicate a contaminant plume along the eastern perimeter of the landfill that has migrated about 300 feet eastward toward an adjacent lake. Concentrations of chloride, ammonia, and nitrate were elevated within the plume. The surficial aquifer consists primarily of sand from 0 to about 68 feet, and sand interbedded with sandstone and limestone from 68 to 220 feet. A slight hydraulic gradient exists, indicating ground-water movement from the landfill toward a lake to the east. Analyses of geoelectric, lithologic, and water-quality data indicate that surface geophysical techniques were successful in determining the areal and vertical extent of leachate migration at this location.

Imaging and quantification of spreading and trapping of carbon dioxide in saline aquifers using meter-scale laboratory experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trevisan, Luca; Pini, Ronny; Cihan, Abdullah

The role of capillary forces during buoyant migration of CO 2 is critical toward plume immobilization within the postinjection phase of a geological carbon sequestration operation. However, the inherent heterogeneity of the subsurface makes it very challenging to evaluate the effects of capillary forces on the storage capacity of these formations and to assess in situ plume evolution. To overcome the lack of accurate and continuous observations at the field scale and to mimic vertical migration and entrapment of realistic CO 2 plumes in the presence of a background hydraulic gradient, we conducted two unique long-term experiments in a 2.44more » m × 0.5 m tank. X-ray attenuation allowed measuring the evolution of a CO 2 -surrogate fluid saturation, thus providing direct insight into capillarity-dominated and buoyancy-dominated flow processes occurring under successive drainage and imbibition conditions. The comparison of saturation distributions between two experimental campaigns suggests that layered-type heterogeneity plays an important role on nonwetting phase (NWP) migration and trapping, because it leads to (i) longer displacement times (3.6 months versus 24 days) to reach stable trapping conditions, (ii) limited vertical migration of the plume (with center of mass at 39% versus 55% of aquifer thickness), and (iii) immobilization of a larger fraction of injected NWP mass (67.2% versus 51.5% of injected volume) as compared to the homogenous scenario. Finally, while these observations confirm once more the role of geological heterogeneity in controlling buoyant flows in the subsurface, they also highlight the importance of characterizing it at scales that are below seismic resolution (1–10 m).« less

Imaging and quantification of spreading and trapping of carbon dioxide in saline aquifers using meter-scale laboratory experiments

DOE PAGES

Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; ...

2016-12-27

The role of capillary forces during buoyant migration of CO 2 is critical toward plume immobilization within the postinjection phase of a geological carbon sequestration operation. However, the inherent heterogeneity of the subsurface makes it very challenging to evaluate the effects of capillary forces on the storage capacity of these formations and to assess in situ plume evolution. To overcome the lack of accurate and continuous observations at the field scale and to mimic vertical migration and entrapment of realistic CO 2 plumes in the presence of a background hydraulic gradient, we conducted two unique long-term experiments in a 2.44more » m × 0.5 m tank. X-ray attenuation allowed measuring the evolution of a CO 2 -surrogate fluid saturation, thus providing direct insight into capillarity-dominated and buoyancy-dominated flow processes occurring under successive drainage and imbibition conditions. The comparison of saturation distributions between two experimental campaigns suggests that layered-type heterogeneity plays an important role on nonwetting phase (NWP) migration and trapping, because it leads to (i) longer displacement times (3.6 months versus 24 days) to reach stable trapping conditions, (ii) limited vertical migration of the plume (with center of mass at 39% versus 55% of aquifer thickness), and (iii) immobilization of a larger fraction of injected NWP mass (67.2% versus 51.5% of injected volume) as compared to the homogenous scenario. Finally, while these observations confirm once more the role of geological heterogeneity in controlling buoyant flows in the subsurface, they also highlight the importance of characterizing it at scales that are below seismic resolution (1–10 m).« less

Imaging and quantification of spreading and trapping of carbon dioxide in saline aquifers using meter-scale laboratory experiments

NASA Astrophysics Data System (ADS)

Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; González-Nicolás, Ana; Illangasekare, Tissa H.

2017-01-01

The role of capillary forces during buoyant migration of CO2 is critical toward plume immobilization within the postinjection phase of a geological carbon sequestration operation. However, the inherent heterogeneity of the subsurface makes it very challenging to evaluate the effects of capillary forces on the storage capacity of these formations and to assess in situ plume evolution. To overcome the lack of accurate and continuous observations at the field scale and to mimic vertical migration and entrapment of realistic CO2 plumes in the presence of a background hydraulic gradient, we conducted two unique long-term experiments in a 2.44 m × 0.5 m tank. X-ray attenuation allowed measuring the evolution of a CO2-surrogate fluid saturation, thus providing direct insight into capillarity-dominated and buoyancy-dominated flow processes occurring under successive drainage and imbibition conditions. The comparison of saturation distributions between two experimental campaigns suggests that layered-type heterogeneity plays an important role on nonwetting phase (NWP) migration and trapping, because it leads to (i) longer displacement times (3.6 months versus 24 days) to reach stable trapping conditions, (ii) limited vertical migration of the plume (with center of mass at 39% versus 55% of aquifer thickness), and (iii) immobilization of a larger fraction of injected NWP mass (67.2% versus 51.5% of injected volume) as compared to the homogenous scenario. While these observations confirm once more the role of geological heterogeneity in controlling buoyant flows in the subsurface, they also highlight the importance of characterizing it at scales that are below seismic resolution (1-10 m).

Vertical Motion Changes Related to North-East Brazil Rainfall Variability: a GCM Simulation

NASA Astrophysics Data System (ADS)

Roucou, Pascal; Oribe Rocha de Aragão, José; Harzallah, Ali; Fontaine, Bernard; Janicot, Serge

1996-08-01

The atmospheric structure over north-east Brazil during anomalous rainfall years is studied in the 11 levels of the outputs of the Laboratoire de Météorologie Dynamique atmospheric general circulation model (LMD AGCM). Seven 19-year simulations were performed using observed sea-surface temperature (SST) corresponding to the period 1970- 1988. The ensemble mean is calculated for each month of the period, leading to an ensemble-averaged simulation. The simulated March-April rainfall is in good agreement with observations. Correlations of simulated rainfall and three SST indices relative to the equatorial Pacific and northern and southern parts of the Atlantic Ocean exhibit stronger relationships in the simulation than in the observations. This is particularly true with the SST gradient in the Atlantic (Atlantic dipole). Analyses on 200 ;hPa velocity potential, vertical velocity, and vertical integral of the zonal component of mass flux are performed for years of abnormal rainfall and positive/negative SST anomalies in the Pacific and Atlantic oceans in March-April during the rainy season over the Nordeste region. The results at 200 hPa show a convergence anomaly over Nordeste and a divergence anomaly over the Pacific concomitant with dry seasons associated with warm SST anomalies in the Pacific and warm (cold) waters in the North (South) Atlantic. During drought years convection inside the ITCZ indicated by the vertical velocity exhibits a displacement of the convection zone corresponding to a northward migration of the ITCZ. The east-west circulation depicted by the zonal divergent mass flux shows subsiding motion over Nordeste and ascending motion over the Pacific in drought years, accompanied by warm waters in the eastern Pacific and warm/cold waters in northern/southern Atlantic. Rainfall variability of the Nordeste rainfall is linked mainly to vertical motion and SST variability through the migration of the ITCZ and the east-west circulation.

Nonlinear Boltzmann equation for the homogeneous isotropic case: Some improvements to deterministic methods and applications to relaxation towards local equilibrium

NASA Astrophysics Data System (ADS)

Asinari, P.

2011-03-01

Boltzmann equation is one the most powerful paradigms for explaining transport phenomena in fluids. Since early fifties, it received a lot of attention due to aerodynamic requirements for high altitude vehicles, vacuum technology requirements and nowadays, micro-electro-mechanical systems (MEMs). Because of the intrinsic mathematical complexity of the problem, Boltzmann himself started his work by considering first the case when the distribution function does not depend on space (homogeneous case), but only on time and the magnitude of the molecular velocity (isotropic collisional integral). The interest with regards to the homogeneous isotropic Boltzmann equation goes beyond simple dilute gases. In the so-called econophysics, a Boltzmann type model is sometimes introduced for studying the distribution of wealth in a simple market. Another recent application of the homogeneous isotropic Boltzmann equation is given by opinion formation modeling in quantitative sociology, also called socio-dynamics or sociophysics. The present work [1] aims to improve the deterministic method for solving homogenous isotropic Boltzmann equation proposed by Aristov [2] by two ideas: (a) the homogeneous isotropic problem is reformulated first in terms of particle kinetic energy (this allows one to ensure exact particle number and energy conservation during microscopic collisions) and (b) a DVM-like correction (where DVM stands for Discrete Velocity Model) is adopted for improving the relaxation rates (this allows one to satisfy exactly the conservation laws at macroscopic level, which is particularly important for describing the late dynamics in the relaxation towards the equilibrium).

Diel and seasonal movement pattern of the dusky grouper Epinephelus marginatus inside a marine reserve.

PubMed

Koeck, Barbara; Pastor, Jérémy; Saragoni, Gilles; Dalias, Nicolas; Payrot, Jérôme; Lenfant, Philippe

2014-03-01

Temporal movement patterns and spawning behaviour of the dusky grouper Epinephelus marginatus were investigated using depth and temperature sensors combined to acoustic telemetry. Results showed that these fish are year-round resident, remaining inside the fully protected area of the marine reserve of Cerbère-Banyuls (65 ha) and display a diurnal activity pattern. Records from depth sensors revealed that groupers range inside small, distinct, and individual territories. Individual variations in habitat depth are only visible on a seasonal scale, i.e., between the spawning season and the rest of the year. In fact, during summer months when the seawater temperature exceeded 20 °C, tagged groupers made vertical spawning migrations of 4-8 m in amplitude. These vertical migrations are characteristic of the reproductive behaviour of dusky groupers, during which they release their gametes. The results are notable for the implementation of management rules in marine protected areas, such as reduced navigation speed, boating or attendance during spawning season. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vertical-cavity surface-emitting laser sources for gigahertz-bandwidth, multiwavelength frequency-domain photon migration

NASA Astrophysics Data System (ADS)

O'Sullivan, Thomas D.; No, Keunsik; Matlock, Alex; Warren, Robert V.; Hill, Brian; Cerussi, Albert E.; Tromberg, Bruce J.

2017-10-01

Frequency-domain photon migration (FDPM) uses modulated laser light to measure the bulk optical properties of turbid media and is increasingly applied for noninvasive functional medical imaging in the near-infrared. Although semiconductor edge-emitting laser diodes have been traditionally used as miniature light sources for this application, we show that vertical-cavity surface-emitting lasers (VCSELs) exhibit output power and modulation performance characteristics suitable for FDPM measurements of tissue optical properties at modulation frequencies exceeding 1 GHz. We also show that an array of multiple VCSEL devices can be coherently modulated at frequencies suitable for FDPM and can improve optical power. In addition, their small size and simple packaging make them an attractive choice as components in wearable sensors and clinical FDPM-based optical spectroscopy systems. We demonstrate the benefits of VCSEL technology by fabricating and testing a unique, compact VCSEL-based optical probe with an integrated avalanche photodiode. We demonstrate sensitivity of the VCSEL-based probe to subcutaneous tissue hemodynamics that was induced during an arterial cuff occlusion of the upper arm in a human subject.

An underwater robo-leader for collective motion studies

NASA Astrophysics Data System (ADS)

Sanchez, Yair; Wilhelmus, Monica M.

2016-11-01

A wide range of aquatic species, from bacteria to large tuna, exhibits collective behavior. It has long been hypothesized that the formation of complex configurations brings an energetic advantage to the members of a group as well as protection against larger predators or harmful agents. Lately, however, laboratory experiments have suggested that both the physics and the behavioral aspects of collective motion yield more complexity than previously attributed. With the goal to understand the fluid mechanical implications behind collective motion in a laboratory setting, we have developed a new device to induce this behavior on demand. Following recent studies of lab-induced vertical migration of Artemia salina, we have designed and constructed a remotely controlled underwater robotic swimmer that acts as a leader for groups of phototactic organisms. Preliminary quantitative flow visualizations done during vertical migration of brine shrimp show that this new instrument does induce collective motion in the laboratory. With this setup, we can address the hydrodynamic effect of having different swarm configurations, a variable that so far has been challenging to study in a controllable and reproducible manner.

Vertical nitrogen flux from the oceanic photic zone by diel migrant zooplankton and nekton

NASA Astrophysics Data System (ADS)

Longhurst, Alan R.; Glen Harrison, W.

1988-06-01

Where the photic zone is a biological steady-state, the downward flux of organic material across the pycnocline to the interior of the ocean is thought to be balanced by upward turbulent flux of inorganic nitrogen across the nutricline. This model ignores a significant downward dissolved nitrogen flux caused by the diel vertical migration of interzonal zooplankton and nekton that feed in the photic zone at night and excrete nitrogenous compounds at depth by day. In the oligotrophic ocean this flux can be equivalent to the flux of particulate organic nitrogen from the photic zone in the form of faecal pellets and organic flocculates. Where nitrogen is the limiting plant nutrient, and the flux by diel migration of interzonal plankton is significant compared to other nitrogen exports from the photic zone, there must be an upward revision of previous estimates for the ratio of new to total primary production in the photic zone if a nutrient balance is to be maintained. This upward revision is of the order 5-100% depending on the oceanographic regime.

[Effects of irrigation of untreated livestock farm wastewater on accumulation and vertical mig- ration of nitrogen and phosphorus in paddy soil].

PubMed

Zhang, Ming-kui; Ahmed Elgodah; Bao, Chen-yan

2014-12-01

Although a series of process techniques for treating wastewater from livestock and poultry breeding have been developed in China and overseas, it is still common in China's rural areas for utilization of the untreated wastewater to irrigate farmland directly because of economic reasons. The impact of untreated wastewater irrigation on accumulation and vertical migration of nitrogen and phosphorus in paddy soil is concerned. Consequently, four representative paddy fields with different histories of livestock farm wastewater irrigation (0, 4, 7, 13 years) were selected for collecting profile soil samples to study the effects of long-term irrigation of untreated livestock farm wastewater on various forms of nitrogen and phosphorus in the soils at different vertical depths. As compared with control field without any irrigation of wastewater, long-term irrigation of untreated livestock farm wastewater significantly increased the accumulation of N and P in the soils with increasing the irrigation year, and the increment of total P in the soil was greater than that of total N. Total P content in surface soil from fields with 4, 7, and 13 years irrigation was increased by 43.6%, 95.2%, and 148.4%, while total N increased by 7.6%, 16.9%, and 28.4%, respectively. Different forms of soil N were increased in order of NH4+ -N, NO3- -N > acid hydrolyzable N > non-acid hydrolyzable N, and soil available P changed much more than total P. Long-term irrigation of untreated livestock farm wastewater could promote vertical migration of soil nitrogen and phosphorus, and increase the pollution risk for groundwater.

Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analysis

NASA Astrophysics Data System (ADS)

Caudron, Corentin; Taisne, Benoit; Kugaenko, Yulia; Saltykov, Vadim

2015-12-01

In contrast of the 1975-76 Tolbachik eruption, the 2012-13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

Is the poleward migration of tropical cyclone maximum intensity associated with a poleward migration of tropical cyclone genesis?

NASA Astrophysics Data System (ADS)

Daloz, Anne Sophie; Camargo, Suzana J.

2018-01-01

A recent study showed that the global average latitude where tropical cyclones achieve their lifetime-maximum intensity has been migrating poleward at a rate of about one-half degree of latitude per decade over the last 30 years in each hemisphere. However, it does not answer a critical question: is the poleward migration of tropical cyclone lifetime-maximum intensity associated with a poleward migration of tropical cyclone genesis? In this study we will examine this question. First we analyze changes in the environmental variables associated with tropical cyclone genesis, namely entropy deficit, potential intensity, vertical wind shear, vorticity, skin temperature and specific humidity at 500 hPa in reanalysis datasets between 1980 and 2013. Then, a selection of these variables is combined into two tropical cyclone genesis indices that empirically relate tropical cyclone genesis to large-scale variables. We find a shift toward greater (smaller) average potential number of genesis at higher (lower) latitudes over most regions of the Pacific Ocean, which is consistent with a migration of tropical cyclone genesis towards higher latitudes. We then examine the global best track archive and find coherent and significant poleward shifts in mean genesis position over the Pacific Ocean basins.

Fluid inclusions in calcite filled opening fractures of the Serra Alta Formation reveal paleotemperatures and composition of diagenetic fluids percolating Permian shales of the Paraná Basin

NASA Astrophysics Data System (ADS)

Teixeira, C. A. S.; Sawakuchi, A. O.; Bello, R. M. S.; Nomura, S. F.; Bertassoli, D. J.; Chamani, M. A. C.

2018-07-01

The thermal and diagenetic evolution of shale units has received renewed focus because of their emergence as unconventional hydrocarbon reservoirs. The Serra Alta Formation (SAF) is a Permian shale unit of the Paraná Basin, which is the largest South American cratonic basin. The SAF stands out as a pathway for aqueous fluids and hydrocarbon migration from the Irati organic-rich shales to the Pirambóia fluvial-eolian sandstone reservoirs. Vertical NNW and NNE opening fractures would be the main pathways for the migration of buried pore waters and aqueous fluids, besides the input of meteoric water. These fractures would be associated to the reactivation of basement discontinuities such as the Jacutinga (NE) and Guapiara (NW) faults. Thus, vertical NNE and NNW associated fractures would represent the main pathways for fluid migration in the studied area. The vertical calcite filled opening fractures from SAF record moderately low salinity (0-4.5 wt % of NaCl eq.) aqueous fluids, suggesting the input of meteoric water in the buried fracture system. Eutectic melting temperatures at -52±5 °C indicate an H2O + NaCl + CaCl2 system with CaCl2 or MgCl2 in solution. Homogenization temperatures recorded in fluid inclusion assemblages (FIAs) of calcite filled opening fractures indicate that the SAF in the studied area reached temperatures above 200 °C, suitable for generation of gaseous hydrocarbons. The recorded paleotemperatures point to a thermal peak associated with Serra Geral volcanic event during the Early Cretaceous, with the thermal effect of volcanic rock cap possibly overcoming the effect of intrusive igneous bodies. The detection of methane in SAF shale pores indicates conditions for hydrocarbon generation. However, additionally studies are necessary to confirm the thermogenic and/or biogenic origin of the methane within the SAF.

Comparison of tracer methods to quantify hydrodynamic exchange within the hyporheic zone

NASA Astrophysics Data System (ADS)

Engelhardt, I.; Piepenbrink, M.; Trauth, N.; Stadler, S.; Kludt, C.; Schulz, M.; Schüth, C.; Ternes, T. A.

2011-03-01

SummaryHydrodynamic exchange between surface-water and groundwater was studied at a river located within the Rhine Valley in Germany. Piezometric pressure heads and environmental tracers such as temperature, stable isotopes, chloride, X-ray contrast media, and artificial sweetener were investigated within the hyporheic zone and river water plume. Vertical profiles of environmental tracers were collected using multi-level wells within the neutral up-gradient zone, beneath the river bed, and within the horizontal proximal and distal down-gradient zone. Infiltration velocities were calculated from pressure heads, temperature fluctuations and gradients. The amount of river water within groundwater was estimated from vertical profiles of chloride, stable isotopes, and persistent pharmaceuticals. Profiles of stable isotopes and chloride reveal the existence of down-welling within the shallow hyporheic zone that is generated by river bed irregularities. Due to down-welling an above-average migration of river water into the hyporheic zone establishes even under upward hydraulic pressure gradients. The investigated environmental tracers could not distinctively display short-time-infiltration velocities representative for flood waves, while average infiltration velocities calculated over several months are uniform displayed. Based on vertical temperature profiles the down-gradient migration of the river water plume could be observed even after long periods of effluent conditions and over a distance of 200 m from the river bank. X-ray contrast media and artificial sweeteners were observed in high concentrations within the proximal zone, but were not detected at a distance of 200 m from the river bank. Using temperature as environmental tracer within the hyporheic zone may result in overestimating the migration of pollutants within the river water plume as the process of natural attenuation will be neglected. Furthermore, temperature was not able to display the effect of down-welling. Stable isotopes and chloride were found to be suitable environmental tracers to forecast the release and fate of organic contaminants within the hyporheic zone.

Short-chain chlorinated paraffins in the soils of two different Chinese cities: Occurrence, homologue patterns and vertical migration.

PubMed

Huang, Yumei; Chen, Laiguo; Feng, Yongbin; Ye, Zhixiang; He, Qiusheng; Feng, Qianhua; Qing, Xian; Liu, Ming; Gao, Bo

2016-07-01

Short-chain chlorinated paraffins (SCCPs) are candidate persistent organic pollutants (POPs) that are under review by the Stockholm Convention. China is currently the largest producer and consumer of chlorinated paraffins (CPs). To study the environmental behavior and fate of SCCPs in the soils of urban and suburban regions, the SCCP concentrations in 88 topsoils and 15 soil columns from land of different use types (e.g., woodland, vegetable field, paddy field and greenbelt) from Guangzhou and Chengdu have been determined. The SCCP concentrations in topsoils from Guangzhou (range: 1.45-25.5ngg(-1) dry weight (dw), average: 10.3ngg(-1) dw) were much higher than those from Chengdu (range: 0.218-3.26ngg(-1) dw, average: 1.43ngg(-1) dw). When compared to previously reported SCCP levels for topsoils from other areas, the SCCP concentrations measured in the present work were quite low. Much higher SCCP concentrations were observed in the greenbelt topsoils from Chengdu relative to the values measured from woodlands and vegetable and paddy fields. The composition profiles suggest that C10Cl6-10 and C11-13Cl6-8 were the major groups of SCCPs in topsoils from the woodlands and vegetable and paddy fields in Guangzhou and Chengdu. Vertical variations of the SCCP concentrations in the soil columns suggest that less chlorinated SCCPs (Cl5-6-SCCPs) are more capable of migrating to the deeper-layer soils than more chlorinated ones (Cl9-10-SCCPs). The SCCP concentrations displayed little dependence on organic matter (OM) for most topsoils (p>0.05), indicating that OM is not the controlling factor in the distribution of SCCPs in the soils. This study analyzed the occurrence, homologue patterns and vertical migration of SCCPs in the topsoils of two Chinese cities with different industrial structures and climate conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Integrated Information Support System (IISS). Volume 8. User Interface Subsystem. Part 14. Virtual Terminal Unit Test Plan

DTIC Science & Technology

1990-09-30

Dynamics Research Corporation: Jones, L.. Glandorf, F. 3a. TYPE OF REPORT 113b. TIME COVERED 114. DATE OF REPORT (Yr.,Mo..Day) 15. PAGE COUNT Final...specific software modules written for each type of real terminal supported. Virtual Terminal Interface: the callable interface to the Virtual Terminal...2000;60000;2;0;100;100;5000;0;0;0;0;0;10 "v-Testing2- DVF - View Fill Area: <ESC>[5;1;2000;50000;20000;30000;20000;50000; 2000;30000&v DVM - View Markers: <ESC

Porcine Burn Shock - Development of a Reliable Model and Response to Sodium, Water, and Plasma Loads Administered for Resuscitation

DTIC Science & Technology

1973-06-01

nm.ddt. inital, Diet n*Mf) Thomas L. Wachtel, M.D. G. R. McCahan, Jr., D.V.M. 0 REPORT CATS 70. TOTAL No. Or PAGE Nb O. or mrs June 1973 - w 78 0. CON...observations of caloric uptake of pigskin, rise in temperature at the dermis-fat interface as a function of both time and skin surface temperature and an...of Iso-, Hypo - and Hypertonic Sodium Solutions in the Treatment of Burn Shock in Mice," Surgery, 57: 698-704, May 1965. 24. Rosenthal, S. M

U.S. Pacific coastal wetland resilience and vulnerability to sea-level rise

USGS Publications Warehouse

Thorne, Karen M.; MacDonald, Glen M.; Guntenspergen, Glenn R.; Ambrose, Richard F.; Buffington, Kevin J.; Dugger, Bruce D.; Freeman, Chase; Janousek, Christopher; Brown, Lauren N.; Rosencranz, Jordan A.; Homquist, James; Smol, John P.; Hargan, Kathryn; Takekawa, John Y.

2018-01-01

We used a first-of-its-kind comprehensive scenario approach to evaluate both the vertical and horizontal response of tidal wetlands to projected changes in the rate of sea-level rise (SLR) across 14 estuaries along the Pacific coast of the continental United States. Throughout the U.S. Pacific region, we found that tidal wetlands are highly vulnerable to end-of-century submergence, with resulting extensive loss of habitat. Using higher-range SLR scenarios, all high and middle marsh habitats were lost, with 83% of current tidal wetlands transitioning to unvegetated habitats by 2110. The wetland area lost was greater in California and Oregon (100%) but still severe in Washington, with 68% submerged by the end of the century. The only wetland habitat remaining at the end of the century was low marsh under higher-range SLR rates. Tidal wetland loss was also likely under more conservative SLR scenarios, including loss of 95% of high marsh and 60% of middle marsh habitats by the end of the century. Horizontal migration of most wetlands was constrained by coastal development or steep topography, with just two wetland sites having sufficient upland space for migration and the possibility for nearly 1:1 replacement, making SLR threats particularly high in this region and generally undocumented. With low vertical accretion rates and little upland migration space, Pacific coast tidal wetlands are at imminent risk of submergence with projected rates of rapid SLR.

Pollution characteristics and environmental risk assessment of typical veterinary antibiotics in livestock farms in Southeastern China.

PubMed

Wang, Na; Guo, Xinyan; Xu, Jing; Kong, Xiangji; Gao, Shixiang; Shan, Zhengjun

2014-01-01

Scientific interest in pollution from antibiotics in animal husbandry has increased during recent years. However, there have been few studies on the vertical exposure characteristics of typical veterinary antibiotics in different exposure matrices from different livestock farms. This study explores the distribution and migration of antibiotics from feed to manure, from manure to soil, and from soil to vegetables, by investigating the exposure level of typical antibiotics in feed, manure, soil, vegetables, water, fish, and pork in livestock farms. A screening environmental risk assessment was conducted to identify the hazardous potential of veterinary antibiotics from livestock farms in southeast China. The results show that adding antibiotics to drinking water as well as the excessive use of antibiotic feed additives may become the major source of antibiotics pollution in livestock farms. Physical and chemical properties significantly affect the distribution and migration of various antibiotics from manure to soil and from soil to plant. Simple migration models can predict the accumulation of antibiotics in soil and plants. The environmental risk assessment results show that more attention should be paid to the terrestrial eco-risk of sulfadiazine, sulfamethazine, sulfamethoxazole, tetracycline, oxytetracycline, chlorotetracycline, ciprofloxacin, and enrofloxacin, and to the aquatic eco-risk of chlorotetracycline, ciprofloxacin, and enrofloxacin. This is the first systematic analysis of the vertical pollution characteristics of typical veterinary antibiotics in livestock farms in southeast China. It also identifies the ecological and human health risk of veterinary antibiotics.

U.S. Pacific coastal wetland resilience and vulnerability to sea-level rise

PubMed Central

Thorne, Karen; MacDonald, Glen; Guntenspergen, Glenn; Ambrose, Richard; Buffington, Kevin; Dugger, Bruce; Freeman, Chase; Janousek, Christopher; Brown, Lauren; Rosencranz, Jordan; Holmquist, James; Smol, John; Hargan, Kathryn; Takekawa, John

2018-01-01

We used a first-of-its-kind comprehensive scenario approach to evaluate both the vertical and horizontal response of tidal wetlands to projected changes in the rate of sea-level rise (SLR) across 14 estuaries along the Pacific coast of the continental United States. Throughout the U.S. Pacific region, we found that tidal wetlands are highly vulnerable to end-of-century submergence, with resulting extensive loss of habitat. Using higher-range SLR scenarios, all high and middle marsh habitats were lost, with 83% of current tidal wetlands transitioning to unvegetated habitats by 2110. The wetland area lost was greater in California and Oregon (100%) but still severe in Washington, with 68% submerged by the end of the century. The only wetland habitat remaining at the end of the century was low marsh under higher-range SLR rates. Tidal wetland loss was also likely under more conservative SLR scenarios, including loss of 95% of high marsh and 60% of middle marsh habitats by the end of the century. Horizontal migration of most wetlands was constrained by coastal development or steep topography, with just two wetland sites having sufficient upland space for migration and the possibility for nearly 1:1 replacement, making SLR threats particularly high in this region and generally undocumented. With low vertical accretion rates and little upland migration space, Pacific coast tidal wetlands are at imminent risk of submergence with projected rates of rapid SLR. PMID:29507876

Short-term variability in the ionosphere due to the nonlinear interaction between the 6 day wave and migrating tides

NASA Astrophysics Data System (ADS)

Gan, Quan; Oberheide, Jens; Yue, Jia; Wang, Wenbin

2017-08-01

Using the thermosphere-ionosphere-mesosphere electrodynamics general circulation model simulations, we investigate the short-term ionospheric variability due to the child waves and altered tides produced by the nonlinear interaction between the 6 day wave and migrating tides. Via the Fourier spectral diagnostics and least squares fittings, the [21 h, W2] and [13 h, W1] child waves, generated by the interaction of the 6 day wave with the DW1 and SW2, respectively, are found to play the leading roles on the subdiurnal variability (e.g., ±10 m/s in the ion drift and 50% in the NmF2) in the F region vertical ion drift changes through the dynamo modulation induced by the low-latitude zonal wind and the meridional wind at higher latitudes. The relatively minor contribution of the [11 h, W3] child wave is explicit as well. Although the [29 h, W0] child wave has the largest magnitude in the E region, its effect is totally absent in the vertical ion drift due to the zonally uniform structure. But the [29 h, W0] child wave shows up in the NmF2. It is found that the NmF2 short-term variability is attributed to the wave modulations on both E region dynamo and in situ F region composition. Also, the altered migrating tides due to the interaction will not contribute to the ionospheric changes significantly.

The use of satellite tags to redefine movement patterns of spiny dogfish (Squalus acanthias) along the U.S. east coast: implications for fisheries management.

PubMed

Carlson, Amy E; Hoffmayer, Eric R; Tribuzio, Cindy A; Sulikowski, James A

2014-01-01

Spiny dogfish (Squalus acanthias) are assumed to be a highly migratory species, making habitual north-south migrations throughout their northwestern Atlantic United States (U.S.) range. Also assumed to be a benthic species, spiny dogfish stock structure is estimated through Northeast Fisheries Science Center (NEFSC) bottom-trawl surveys. Recent anomalies in population trends, including a recent four-fold increase in estimated spawning stock biomass, suggest alternative movement patterns could exist for this shark species. To obtain a better understanding of the horizontal and vertical movement dynamics of this species, Microwave Telemetry pop-up satellite archival X-Tags were attached to forty adult spiny dogfish at the northern (Gulf of Maine) and southern (North Carolina) extents of their core U.S. geographic range. Reconstructed geolocation tracks ranging in lengths from two to 12 months suggest that the seasonal migration patterns appear to be local in nature to each respective northern and southern deployment site, differing from previously published migration paradigms. Differences in distance and direction traveled between seasonal geolocations possibly indicate separate migratory patterns between groups. Kernel utilization distribution models also suggest strong separate core home ranges. Significant differences in seasonal temperature and depths between the two regions further substantiate the possibility of separate regional movement patterns between the two groups. Vertical utilization also suggests distinct diel patterns and that this species may not utilize the benthos as previously thought, potentially decreasing availability to benthic gear.

The Use of Satellite Tags to Redefine Movement Patterns of Spiny Dogfish (Squalus acanthias) along the U.S. East Coast: Implications for Fisheries Management

PubMed Central

Carlson, Amy E.; Hoffmayer, Eric R.; Tribuzio, Cindy A.; Sulikowski, James A.

2014-01-01

Spiny dogfish (Squalus acanthias) are assumed to be a highly migratory species, making habitual north-south migrations throughout their northwestern Atlantic United States (U.S.) range. Also assumed to be a benthic species, spiny dogfish stock structure is estimated through Northeast Fisheries Science Center (NEFSC) bottom-trawl surveys. Recent anomalies in population trends, including a recent four-fold increase in estimated spawning stock biomass, suggest alternative movement patterns could exist for this shark species. To obtain a better understanding of the horizontal and vertical movement dynamics of this species, Microwave Telemetry pop-up satellite archival X-Tags were attached to forty adult spiny dogfish at the northern (Gulf of Maine) and southern (North Carolina) extents of their core U.S. geographic range. Reconstructed geolocation tracks ranging in lengths from two to 12 months suggest that the seasonal migration patterns appear to be local in nature to each respective northern and southern deployment site, differing from previously published migration paradigms. Differences in distance and direction traveled between seasonal geolocations possibly indicate separate migratory patterns between groups. Kernel utilization distribution models also suggest strong separate core home ranges. Significant differences in seasonal temperature and depths between the two regions further substantiate the possibility of separate regional movement patterns between the two groups. Vertical utilization also suggests distinct diel patterns and that this species may not utilize the benthos as previously thought, potentially decreasing availability to benthic gear. PMID:25068584

Vertical Migration Potential of Metal Contaminants at Small Arms Firing Ranges, Camp Edwards Military Reservation, Massachusetts.

DTIC Science & Technology

1998-03-01

halloysite on lead concentration in solution 57 Figure 41. Solubility of lead carbonate as a function of pH for a total activity aH2C03...Effects of adsorption by halloysite (a clay) on lead concentration in solution. Contours are equilibrium lead concentrations at different clay

Engineered Models of Confined Cell Migration

PubMed Central

Paul, Colin D.; Hung, Wei-Chien; Wirtz, Denis; Konstantopoulos, Konstantinos

2017-01-01

Cells in the body are physically confined by neighboring cells, tissues, and the extracellular matrix. Although physical confinement modulates intracellular signaling and the underlying mechanisms of cell migration, it is difficult to study in vivo. Furthermore, traditional two-dimensional cell migration assays do not recapitulate the complex topographies found in the body. Therefore, a number of experimental in vitro models that confine and impose forces on cells in well-defined microenvironments have been engineered. We describe the design and use of microfluidic microchannel devices, grooved substrates, micropatterned lines, vertical confinement devices, patterned hydrogels, and micropipette aspiration assays for studying cell responses to confinement. Use of these devices has enabled the delineation of changes in cytoskeletal reorganization, cell–substrate adhesions, intracellular signaling, nuclear shape, and gene expression that result from physical confinement. These assays and the physiologically relevant signaling pathways that have been elucidated are beginning to have a translational and clinical impact. PMID:27420571

Energy cost and putative benefits of cellular mechanisms modulating buoyancy in aflagellate marine phytoplankton.

PubMed

Lavoie, Michel; Raven, John A; Levasseur, Maurice

2016-04-01

Little information is available on the energetics of buoyancy modulation in aflagellate phytoplankton, which comprises the majority of autotrophic cells found in the ocean. Here, we computed for three aflagellate species of marine phytoplankton (Emiliania huxleyi, Thalassiosira pseudonana, and Ethmodiscus rex) the theoretical minimum energy cost as photons absorbed and nitrogen resource required of the key physiological mechanisms (i.e., replacement of quaternary ammonium by dimethyl-sulfoniopropionate, storage of polysaccharides, and cell wall biosynthesis) affecting the cell's vertical movement as a function of nitrogen (N) availability. These energy costs were also normalized to the capacity of each buoyancy mechanism to modulate sinking or rising rates based on Stokes' law. The three physiological mechanisms could act as ballast in the three species tested in conditions of low N availability at a low fraction (<12%) of the total photon energy cost for growth. Cell wall formation in E. huxleyi was the least costly ballast strategy, whereas in T. pseudonana, the photon energy cost of the three ballast strategies was similar. In E. rex, carbohydrate storage and mobilization appear to be energetically cheaper than modulations in organic solute synthesis to achieve vertical migration. This supports the carbohydrate-ballast strategy for vertical migration for this species, but argues against the theory of replacement of low- or high-density organic solutes. This study brings new insights into the energy cost and potential selective advantages of several strategies modulating the buoyancy of aflagellate marine phytoplankton. © 2016 Phycological Society of America.

Ontogenetic behavior and migration of Volga River Russian sturgeon, Acipenser gueldenstaedtii, with a note on adaptive significance of body color

USGS Publications Warehouse

Kynard, B.; Zhuang, P.; Zhang, L.; Zhang, T.; Zhang, Z.

2002-01-01

We conducted laboratory experiments with Volga River Russian sturgeon, Acipenser gueldenstaedtii, to develop a conceptual model of early behavior. We daily observed fish from day-0 (embryos, first life interval after hatching) to day-29 feeding larvae for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Hatchling embryos initiated a downstream migration, which suggests that predation risk of embryos at spawning sites is high. Migration peaked on days 0-5 and ceased on day 7 (8-day migration). Migrants preferred bright, open habitat and early migrants swam-up far above the bottom (maximum daily median, 140 cm) in a vertical swim tube. Post-migrant embryos did not prefer bright illumination but continued to prefer white substrate, increased use of cover habitat, and swam on the bottom. Larvae initiated feeding on day 10 after 170.6 cumulative temperature degree-days. Larvae did not migrate, weakly preferred bright illumination, preferred white substrate and open habitat, and swam near the bottom (daily median 5-78 cm). The lack of a strong preference by larvae for bright illumination suggests foraging relies more on olfaction than vision for locating prey. A short migration by embryos would disperse wild sturgeon from a spawning area, but larvae did not migrate, so a second later migration by juveniles disperses young sturgeon to the sea (2-step migration). Embryo and larva body color was light tan and tail color was black. The migration, behavior, and light body color of Russian sturgeon embryos was similar to species of Acipenser and Scaphirhynchus in North America and to Acipenser in Asia that migrate after hatching as embryos. The similarity in migration style and body color among species with diverse phylogenies likely reflects convergence for common adaptations across biogeographic regions. ?? 2002 Kluwer Academic Publishers.

Lateral migration of a microdroplet under optical forces in a uniform flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Hyunjun; Chang, Cheong Bong; Jung, Jin Ho

2014-12-15

The behavior of a microdroplet in a uniform flow and subjected to a vertical optical force applied by a loosely focused Gaussian laser beam was studied numerically. The lattice Boltzmann method was applied to obtain the two-phase flow field, and the dynamic ray tracing method was adopted to calculate the optical force. The optical forces acting on the spherical droplets agreed well with the analytical values. The numerically predicted droplet migration distances agreed well with the experimentally obtained values. Simulations of the various flow and optical parameters showed that the droplet migration distance nondimensionalized by the droplet radius is proportionalmore » to the S number (z{sub d}/r{sub p} = 0.377S), which is the ratio of the optical force to the viscous drag. The effect of the surface tension was also examined. These results indicated that the surface tension influenced the droplet migration distance to a lesser degree than the flow and optical parameters. The results of the present work hold for the refractive indices of the mean fluid and the droplet being 1.33 and 1.59, respectively.« less

Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analyses

NASA Astrophysics Data System (ADS)

Taisne, B.; Caudron, C.; Kugaenko, Y.; Saltykov, V.

2015-12-01

In contrast of the 1975-76 Tolbachik eruption, the 2012-2013 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma transfer prior to this important eruption. We highlighted a clear migration of the source of the microseismicity within the seismic swarm, starting 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava extrusion, was recorded (at ~11:00 UTC, 27 November 2012). In order to get a first order approximation of the location of the magma, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest a migration toward the eruptive vent. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano that would interact at shallower depth with an intermediate storage region and initiate the lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

Seasonal effects of wind conditions on migration patterns of soaring American white pelican.

PubMed

Gutierrez Illan, Javier; Wang, Guiming; Cunningham, Fred L; King, D Tommy

2017-01-01

Energy and time expenditures are determinants of bird migration strategies. Soaring birds have developed migration strategies to minimize these costs, optimizing the use of all the available resources to facilitate their displacement. We analysed the effects of different wind factors (tailwind, turbulence, vertical updrafts) on the migratory flying strategies adopted by 24 satellite-tracked American white pelicans (Pelecanus erythrorhynchos) throughout spring and autumn in North America. We hypothesize that different wind conditions encountered along migration routes between spring and autumn induce pelicans to adopt different flying strategies and use of these wind resources. Using quantile regression and fine-scale atmospheric data, we found that the pelicans optimized the use of available wind resources, flying faster and more direct routes in spring than in autumn. They actively selected tailwinds in both spring and autumn displacements but relied on available updrafts predominantly in their spring migration, when they needed to arrive at the breeding regions. These effects varied depending on the flying speed of the pelicans. We found significant directional correlations between the pelican migration flights and wind direction. In light of our results, we suggest plasticity of migratory flight strategies by pelicans is likely to enhance their ability to cope with the effects of ongoing climate change and the alteration of wind regimes. Here, we also demonstrate the usefulness and applicability of quantile regression techniques to investigate complex ecological processes such as variable effects of atmospheric conditions on soaring migration.

Seasonal effects of wind conditions on migration patterns of soaring American white pelican

PubMed Central

Wang, Guiming; Cunningham, Fred L.; King, D. Tommy

2017-01-01

Energy and time expenditures are determinants of bird migration strategies. Soaring birds have developed migration strategies to minimize these costs, optimizing the use of all the available resources to facilitate their displacement. We analysed the effects of different wind factors (tailwind, turbulence, vertical updrafts) on the migratory flying strategies adopted by 24 satellite-tracked American white pelicans (Pelecanus erythrorhynchos) throughout spring and autumn in North America. We hypothesize that different wind conditions encountered along migration routes between spring and autumn induce pelicans to adopt different flying strategies and use of these wind resources. Using quantile regression and fine-scale atmospheric data, we found that the pelicans optimized the use of available wind resources, flying faster and more direct routes in spring than in autumn. They actively selected tailwinds in both spring and autumn displacements but relied on available updrafts predominantly in their spring migration, when they needed to arrive at the breeding regions. These effects varied depending on the flying speed of the pelicans. We found significant directional correlations between the pelican migration flights and wind direction. In light of our results, we suggest plasticity of migratory flight strategies by pelicans is likely to enhance their ability to cope with the effects of ongoing climate change and the alteration of wind regimes. Here, we also demonstrate the usefulness and applicability of quantile regression techniques to investigate complex ecological processes such as variable effects of atmospheric conditions on soaring migration. PMID:29065188

Seasonal changes in the vertical distribution of two types of multicellular magnetotactic prokaryotes in the sediment of Lake Yuehu, China.

PubMed

Liu, Jia; Zhang, Wenyan; Du, Haijian; Leng, Xiaoyun; Li, Jin-Hua; Pan, Hongmiao; Xu, Jianhong; Wu, Long-Fei; Xiao, Tian

2018-04-24

There are two genetically distinct morphological types of multicellular magnetotactic prokaryotes (MMPs) in the intertidal zone of Lake Yuehu (China): ellipsoidal MMPs (eMMPs) and spherical MMPs (sMMPs). We studied the vertical distribution of both types of MMPs in the sediment at Lake Yuehu during 1 year. Both types of MMPs were observed at sediment depths ranging from 1 to 34 cm, depending on the seasons. The eMMPs distributed at depths of 2-34 cm during spring, 1-11 cm during summer, 2-21 cm during autumn and 9-32 cm during winter. The eMMP species Candidatus Magnetananas rongchenensis, with magnetite magnetosomes, dominated at all distribution depths. These results suggested that Ca. M. rongchenensis migrated vertically during four seasons. The vertical profiles of oxidation-reduction potential (ORP) in Lake Yuehu changed seasonally, and these changes coincided with the seasonal distribution of MMPs, suggesting that the ORP affected the vertical distribution of MMPs. In addition, high concentrations of ammonium and silicate were associated with low abundances of MMPs. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Modeling biophysical/biogeochemical/ecological/ocean/atmosphere two-way interactions using NCEP CFS/SSiB5/TRIFFID/DAYCENT: challenge and promising

NASA Astrophysics Data System (ADS)

Xue, Y.; Liu, Y.; Cox, P. M.; De Sales, F.; Lee, J.; Marx, L.; Hartman, M. D.; Yang, R.; Parton, W. J.; Qiu, B.; Ek, M. B.

2016-12-01

Evaluations of several dynamic vegetation models' (DVM) performances in the offline experiments and in the CMIP5 simulations suggest that most of the DVMs substantially overestimate leaf area index (LAI) and length of the growing season, which contribute to overestimation in their coupled models' precipitation. These results suggest important deficiencies in today's DVMs but also show the importance of proper ecological processes in the Earth System Modeling. We have developed a water-carbon-energy balance-based ecosystem model (SSiB4/TRIFFID) and verified it with field and satellite measurement at seasonal to decadal and longer scales. In the global offline tests, the model was integrated from 1950 to 2010 driven by observed meteorological forcing. The simulated trend and decadal variabilities in surface ecosystem conditions (e.g., Plant functional types, LAI, GPP), and surface water and energy balances are analyzed; further experiments and analyses are carried to isolate the contribution due to elevated atmospheric carbon concentration, global warming, soil moisture, and climate variability. How nitrogen processes simulated by the DayCent model Climate Forecast System (CFS) model, which has consistently shown improvements in simulated atmospheric & ocean conditions compared with those runs with specified vegetation conditions. In an experiment, two parametrizations that calculate the mean water potential in soil layers, which affect transpiration and plants' mortality, are tested. It shows that these two methods have substantial impact on global decadal variability of precipitation and surface temperature, with even opposite signs over some regions in the worlds. These results show the uncertainty in DVM modeling with significant implication for the future prediction. It is imperative to evaluate DVMs with comprehensive observational data.

The disconnected values (intervention) model for promoting healthy habits in religious institutions.

PubMed

Anshel, Mark H

2010-03-01

The purpose of this article is to provide an intervention model that can be used by religious leaders for changing health behavior among practicing members of religious communities. The intervention does not require extensive training or licensure in counseling psychology. At the heart of this model is the acknowledgement that a person's negative habits (e.g., lack of exercise, poor nutrition) and his or her deepest values and beliefs (e.g., faith, health, family) are often misaligned, or disconnected. In addition, the unhealthy outcomes from these habits are contrary to the scriptural traditions of the world religions and thus are especially relevant to individuals who practice their religious beliefs. The Sacred Scriptures of Judaism and Christianity, for example, are replete with teachings that extol the virtues of practicing habits that promote good health and energy. In addition, evidence is mounting in the existing health intervention literature that adopting permanent and desirable changes in health behavior have not been successful, and that adherence to desirable habits such as exercise and proper nutrition is short-lived. The Disconnected Values Model (DVM) provides a novel approach for enhancing health behavior change within the context of the mission of most religious institutions. The model is compatible with skills presented by religious leaders, who possess more credibility and influence in changing the behavior of members and service attendees of their respective religious institutions. The religious leader's role is to provide the client with faith-based incentives to initiate and maintain changes in their health behaviors, and perhaps to provide resources for the individual to pursue an action plan. A case study is described in which the DVM intervention was used successfully with an individual of strong faith.

Accurate prediction of protein-protein interactions by integrating potential evolutionary information embedded in PSSM profile and discriminative vector machine classifier.

PubMed

Li, Zheng-Wei; You, Zhu-Hong; Chen, Xing; Li, Li-Ping; Huang, De-Shuang; Yan, Gui-Ying; Nie, Ru; Huang, Yu-An

2017-04-04

Identification of protein-protein interactions (PPIs) is of critical importance for deciphering the underlying mechanisms of almost all biological processes of cell and providing great insight into the study of human disease. Although much effort has been devoted to identifying PPIs from various organisms, existing high-throughput biological techniques are time-consuming, expensive, and have high false positive and negative results. Thus it is highly urgent to develop in silico methods to predict PPIs efficiently and accurately in this post genomic era. In this article, we report a novel computational model combining our newly developed discriminative vector machine classifier (DVM) and an improved Weber local descriptor (IWLD) for the prediction of PPIs. Two components, differential excitation and orientation, are exploited to build evolutionary features for each protein sequence. The main characteristics of the proposed method lies in introducing an effective feature descriptor IWLD which can capture highly discriminative evolutionary information from position-specific scoring matrixes (PSSM) of protein data, and employing the powerful and robust DVM classifier. When applying the proposed method to Yeast and H. pylori data sets, we obtained excellent prediction accuracies as high as 96.52% and 91.80%, respectively, which are significantly better than the previous methods. Extensive experiments were then performed for predicting cross-species PPIs and the predictive results were also pretty promising. To further validate the performance of the proposed method, we compared it with the state-of-the-art support vector machine (SVM) classifier on Human data set. The experimental results obtained indicate that our method is highly effective for PPIs prediction and can be taken as a supplementary tool for future proteomics research.

Paleoclimate reconstruction through Bayesian data assimilation

NASA Astrophysics Data System (ADS)

Fer, I.; Raiho, A.; Rollinson, C.; Dietze, M.

2017-12-01

Methods of paleoclimate reconstruction from plant-based proxy data rely on assumptions of static vegetation-climate link which is often established between modern climate and vegetation. This approach might result in biased climate constructions as it does not account for vegetation dynamics. Predictive tools such as process-based dynamic vegetation models (DVM) and their Bayesian inversion could be used to construct the link between plant-based proxy data and palaeoclimate more realistically. In other words, given the proxy data, it is possible to infer the climate that could result in that particular vegetation composition, by comparing the DVM outputs to the proxy data within a Bayesian state data assimilation framework. In this study, using fossil pollen data from five sites across the northern hardwood region of the US, we assimilate fractional composition and aboveground biomass into dynamic vegetation models, LINKAGES, LPJ-GUESS and ED2. To do this, starting from 4 Global Climate Model outputs, we generate an ensemble of downscaled meteorological drivers for the period 850-2015. Then, as a first pass, we weigh these ensembles based on their fidelity with independent paleoclimate proxies. Next, we run the models with this ensemble of drivers, and comparing the ensemble model output to the vegetation data, adjust the model state estimates towards the data. At each iteration, we also reweight the climate values that make the model and data consistent, producing a reconstructed climate time-series dataset. We validated the method using present-day datasets, as well as a synthetic dataset, and then assessed the consistency of results across ecosystem models. Our method allows the combination of multiple data types to reconstruct the paleoclimate, with associated uncertainty estimates, based on ecophysiological and ecological processes rather than phenomenological correlations with proxy data.

Vertical nanopillars for in situ probing of nuclear mechanics in adherent cells

PubMed Central

Hanson, Lindsey; Zhao, Wenting; Lou, Hsin-Ya; Lin, Ziliang Carter; Lee, Seok Woo; Chowdary, Praveen; Cui, Yi; Cui, Bianxiao

2016-01-01

The mechanical stability and deformability of the cell nucleus are crucial to many biological processes, including migration, proliferation and polarization. In vivo, the cell nucleus is frequently subjected to deformation on a variety of length and time scales, but current techniques for studying nuclear mechanics do not provide access to subnuclear deformation in live functioning cells. Here we introduce arrays of vertical nanopillars as a new method for the in situ study of nuclear deformability and the mechanical coupling between the cell membrane and the nucleus in live cells. Our measurements show that nanopillar-induced nuclear deformation is determined by nuclear stiffness, as well as opposing effects from actin and intermediate filaments. Furthermore, the depth, width and curvature of nuclear deformation can be controlled by varying the geometry of the nanopillar array. Overall, vertical nanopillar arrays constitute a novel approach for non-invasive, subcellular perturbation of nuclear mechanics and mechanotransduction in live cells. PMID:25984833

Theories of transporting processes of Cu in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Su, Chunhua; Zhu, Sixi; Wu, Yunjie; Zhou, Wei

2018-02-01

Many marine bays have been polluted along with the rapid development of industry and population size, and understanding the transporting progresses of pollutants is essential to pollution control. In order to better understanding the transporting progresses of pollutants in marine, this paper carried on a comprehensive research of the theories of transporting processes of Cu in Jiaozhou Bay. Results showed that the transporting processes of Cu in this bay could be summarized into seven key theories including homogeneous theory, environmental dynamic theory, horizontal loss theory, source to waters transporting theory, sedimentation transporting theory, migration trend theory and vertical transporting theory, respectively. These theories helpful to better understand the migration progress of pollutants in marine bay.

The diel migrations and distributions within a mesopelagic community in the North East Atlantic. 7. Siphonophores

NASA Astrophysics Data System (ADS)

Pugh, P. R.

Siphonophores are by far the dominant macroplanktonic-micronektonic taxon of animals present in the 48 hr series of samples as a whole. A total of 35 species were identified, with four of these making up over 90% of the total numbers. Details of how the siphonophore population was estimated are discussed, but few species underwent clear cut diel vertical migration although there was considerable variability in their distributions over the sampling periods. The hydrography of the sampling area was investigated in relation to its possible effects on the faunal assemblages, and the important role of siphonophores as carnivores in the planktonic food chain was discussed.

Downward migration of radiocesium in an abandoned paddy soil after the Fukushima Dai-ichi Nuclear Power Plant accident.

PubMed

Takahashi, Junko; Wakabayashi, Shokichi; Tamura, Kenji; Onda, Yuichi

2018-02-01

After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, continuous monitoring of the detailed vertical distribution of radiocesium in soil is required to evaluate the fate of radiocesium and establish strategies for remediation and management of the contaminated land. It is especially important to investigate paddy soil because little knowledge has been accumulated for paddy soil and wetland rice is a major staple in Japan. Therefore, we monitored the vertical distribution of 137 Cs in abandoned paddy soil in a planned evacuation zone from June 2011 to March 2016. The decontamination works (i.e., 5 cm of surface soil removal and re-covering with uncontaminated soil) were conducted by the government in 2015. As a result of monitoring, the 137 Cs gradually migrated downward with time and the 137 Cs concentration in the 0-10 cm soil was almost homogenous in October 2014, although it was non-cultivated. The liner relationship was obtained between the median depth, which is the thickness of a soil layer containing half of the total 137 Cs inventory, and the time after the accident, indicating the migration rate was constant (1.3 cm y -1 ) before the decontamination works. After the decontamination works, the 137 Cs concentration in the uppermost surface layer was reduced by 90%, however the total 137 Cs inventory was reduced by only 50-70%. It was shown that the efficiency of 137 Cs removal by the decontamination works decrease linearly over time in fields like the studied paddy, in which the homogenization of 137 Cs concentration occurred. Conversely, the downward migration of 137 Cs to subsurface layers deeper than 10 cm (i.e., plowpan layer) with low permeability rarely occurred. It is expected that these unique trends in distribution and migration of 137 Cs would be found in abandoned paddy soils with properties similar to the studied soil, sandy loam but poorly drained because of the low permeable plowpan layer, although further validation is necessary. Copyright © 2017 Elsevier Ltd. All rights reserved.

Present and past ground-water conditions in the Morrison Formation in southwestern Colorado and southeastern Utah

USGS Publications Warehouse

Phoenix, D.A.

1952-01-01

Whatever mode of origin is used to explain the deposits, geologists almost without exception, agree that the metals were transported by solutions that have migrated through the sediments for considerable distances. For this reason, a study of the horizontal and vertical transmissibility characteristics of all exposed sedimentary formations on the Colorado Plateau is planned.

VERTICAL MIGRATION OF RADIONUCLIDES IN THE VICINITY OF THE CHERNOBYL CONFINEMENT SHELTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farfan, E.; Jannik, T.; Marra, J.

2011-10-01

Studies on vertical migration of Chernobyl-origin radionuclides in the 5-km zone of the Chernobyl Nuclear Power Plant (ChNPP) in the area of the Red Forest experimental site were completed. Measurements were made by gamma spectrometric methods using high purity germanium (HPGe) detectors with beryllium windows. Alpha-emitting isotopes of plutonium were determined by the measurement of the x-rays from their uranium progeny. The presence of {sup 60}Co, {sup 134,137}Cs, {sup 154,155}Eu, and {sup 241}Am in all soil layers down to a depth of 30 cm was observed. The presence of {sup 137}Cs and {sup 241}Am were noted in the area containingmore » automorphous soils to a depth of 60 cm. In addition, the upper soil layers at the test site were found to contain {sup 243}Am and {sup 243}Cm. Over the past ten years, the {sup 241}Am/{sup 137}Cs ratio in soil at the experimental site has increased by a factor of 3.4, nearly twice as much as would be predicted based solely on radioactive decay. This may be due to 'fresh' fallout emanating from the ChNPP Confinement Shelter.« less

Diurnal vertical migration of Cochlodinium polykrikoides during the red tide in Korean coastal sea waters.

PubMed

Kim, Young Sug; Jeong, Chang Su; Seong, Gi Tak; Han, In Sung; Lee, Young Sik

2010-09-01

The diurnal vertical migration of Cochlodinium polykrikoides (C. polykrikoides), which caused a red tide in the Korean coastal waters of the East Sea/Sea of Japan in September 2003, was examined by determining the time-dependent changes in the density of living cells in relation to the depth of the water column. The ascent of this species into the surface layer (depth of water 2 m) occurred during 1400-1500. The descent started at 1600 and a high distribution rate (86%) at 15-20 m was observed at 0300. During the ascent, the cells were widely distributed at each depth level from 0600 hr and at 0800-1100, the cells were primarily distributed in the middle layer (0-6 m). The concentration of dissolved inorganic nitrogen was generally < or = 2.86 micromol l(-1), but at 1400-1500, the concentration in the surface layer reduced to < or = 0.14 micromol l(-1). Moreover, the concentration gradually increased as the depth increased to > or = 5 m. These results showed that the nutrient-consumption rate associated with the proliferation of C. polykrikoides during a red tide is more influenced by the inorganic-nitrogen resources ratherthan the inorganic-phosphorus compounds.

Ecology of an estuarine mysid shrimp in the Columbia River (USA)

USGS Publications Warehouse

Haskell, C.A.; Stanford, J.A.

2006-01-01

The estuarine mysid, Neomysis mercedis, has colonized John Day and other run-of-the-river Reservoirs of the Columbia River, over 400 km from the estuary. In John Day Reservoir N. mercedis numbers peaked (2 m-3) in August in areas near the dam in association with lower water velocity and softer bottom than at the upstream sampling sites. Neomysis broods were primarily released in late spring and early fall. Gut content analysis showed that Neomysis feeds mostly on cladoceran zooplankton and rotifers in John Day Reservoir. Diel vertical migration was documented, with daytime distribution restricted to the bottom and preferentially to the soft-textured sediments in the deepest areas. Common pelagic fishes in the reservoir, especially juvenile American shad (Alosa sapidissima) and chinook salmon (Oncorhynchus tshawytscha), are daytime zooplankton feeders that cannot prey on Neomysis owing to mysid diel vertical migration. Thus, Neomysis has become an important food web component in John Day Reservoir. We also collected N. mercedis further upstream in Lower Granite Reservoir, where another estuarine crustacean, Corophium salmonis, also is reported, underscoring the need to better understand the role of these estuarine invertebrates in the trophic ecology of the Columbia River. Copyright ?? 2006 John Wiley & Sons, Ltd.

Coastal wetland adaptation to sea level rise: Quantifying potential for landward migration and coastal squeeze

USGS Publications Warehouse

Borchert, Sinéad M.; Osland, Michael J.; Enwright, Nicholas M.; Griffith, Kereen

2018-01-01

Coastal wetland ecosystems are expected to migrate landwards in response to rising seas. However, due to differences in topography and coastal urbanization, estuaries vary in their ability to accommodate migration. Low‐lying urban areas can constrain migration and lead to wetland loss (i.e. coastal squeeze), especially where existing wetlands cannot keep pace with rising seas via vertical adjustments. In many estuaries, there is a pressing need to identify landward migration corridors and better quantify the potential for landward migration and coastal squeeze.We quantified and compared the area available for landward migration of tidal saline wetlands and the area where urban development is expected to prevent migration for 39 estuaries along the wetland‐rich USA Gulf of Mexico coast. We did so under three sea level rise scenarios (0.5, 1.0, and 1.5 m by 2100).Within the region, the potential for wetland migration is highest within certain estuaries in Louisiana and southern Florida (e.g. Atchafalaya/Vermilion Bays, Mermentau River, Barataria Bay, and the North and South Ten Thousand Islands estuaries).The potential for coastal squeeze is highest in estuaries containing major metropolitan areas that extend into low‐lying lands. The Charlotte Harbor, Tampa Bay, and Crystal‐Pithlachascotee estuaries (Florida) have the highest amounts of urban land expected to constrain wetland migration. Urban barriers to migration are also high in the Galveston Bay (Texas) and Atchafalaya/Vermilion Bays (Louisiana) estuaries.Synthesis and applications. Coastal wetlands provide many ecosystem services that benefit human health and well‐being, including shoreline protection and fish and wildlife habitat. As the rate of sea level rise accelerates in response to climate change, coastal wetland resources could be lost in areas that lack space for landward migration. Migration corridors are particularly important in highly urbanized estuaries where, due to low‐lying coastal development, there is not space for wetlands to move and adapt to sea level rise. Future‐focused landscape conservation plans that incorporate the protection of wetland migration corridors can increase the adaptive capacity of these valuable ecosystems and simultaneously decrease the vulnerability of coastal human communities to the harmful effects of rising seas.

Esthetic evaluation of dental and gingival asymmetries.

PubMed

Fernandes, Liliana; Pinho, Teresa

2015-06-01

The aim of this study was to determine which smile asymmetries were less esthetic, dental or gingival. Laypeople (297), generalists (223), prosthodontists (50) and orthodontists (49), evaluated the esthetics of digitally-modified images taken from the same frontal intra-oral photograph, using the same lips, simulating upper maxillary midline shift, occlusal plane inclination, asymmetric incisal edge and asymmetric gingival migration. The images were later paired into 3 groups. The only ones considered esthetic were the asymmetric incisal edge of the 0.5 mm shorter upper central incisor and the asymmetric gingival migration (2 mm) of the upper central incisor. In the paired images, upper maxillary midline shift vs. occlusal plane inclination, the former was rated less esthetic, while in the asymmetric incisal edge vs. asymmetric gingival migration pair, the latter was considered to be less esthetic. Laypeople and generalists consider smiles more attractive. The only images considered esthetic were the asymmetric incisal edge of the central incisor shorter by 0.5 mm and the 2 mm asymmetric gingival migration of the upper central incisor. In the horizontal plane (maxillary midline shift vs. occlusal plane cant), the dental asymmetries were considered less esthetic than the gingival asymmetries. However, in the vertical plane (asymmetric incisal edge vs. asymmetric gingival migration) the opposite was recorded. Copyright © 2015 CEO. Published by Elsevier Masson SAS. All rights reserved.

Pressure solution and microfracturing in primary oil migration, Upper Cretaceous Austin Chalk, Texas Gulf Coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chanchani, J.; Berg, R.R.; Lee, C.I.

1996-09-01

The Upper Cretaceous Austin Chalk is a well known source rock and fractured reservoir in the Gulf Coast. Production is mainly from tectonic fractures, and the mechanism by which oil migrated from the matrix into the fractures is poorly understood. Microfracturing due to oil generation offers a possible explanation for the mechanism of the primary migration of oil in the Austin Chalk. Petrographic study shows that the major components of the primary migration system are the solution seams and the associated microfractures. Pressure solution is manifest as centimeter to millimeter-scale solution seams and smaller microseams. The solution seams are compositesmore » formed by the superposition of the smaller microseams. A significant amount of organic matter was concentrated in the seams along with other insoluble residue. Swarms of horizontal microfractures, many of them filled with calcite and other residue, are associated with the seams. Vertical, tectonic fractures that constitute the reservoir porosity, intersect the solution seams. Pressure solution concentrated organic matter within the solution seams and oil was generated there. It is postulated that the accompanying increase in fluid volume raised the pore pressures and fractured the rock. The newly created microfractures were avenues for migration of fluids from the seams, perhaps by microfracture propagation.« less

Disruption of vertical motility by shear triggers formation of thin phytoplankton layers.

PubMed

Durham, William M; Kessler, John O; Stocker, Roman

2009-02-20

Thin layers of phytoplankton are important hotspots of ecological activity that are found in the coastal ocean, meters beneath the surface, and contain cell concentrations up to two orders of magnitude above ambient concentrations. Current interpretations of their formation favor abiotic processes, yet many phytoplankton species found in these layers are motile. We demonstrated that layers formed when the vertical migration of phytoplankton was disrupted by hydrodynamic shear. This mechanism, which we call gyrotactic trapping, can be responsible for the thin layers of phytoplankton commonly observed in the ocean. These results reveal that the coupling between active microorganism motility and ambient fluid motion can shape the macroscopic features of the marine ecological landscape.

1.3 μm wavelength vertical cavity surface emitting laser fabricated by orientation-mismatched wafer bonding: A prospect for polarization control

NASA Astrophysics Data System (ADS)

Okuno, Yae L.; Geske, Jon; Gan, Kian-Giap; Chiu, Yi-Jen; DenBaars, Steven P.; Bowers, John E.

2003-04-01

We propose and demonstrate a long-wavelength vertical cavity surface emitting laser (VCSEL) which consists of a (311)B InP-based active region and (100) GaAs-based distributed Bragg reflectors (DBRs), with an aim to control the in-plane polarization of output power. Crystal growth on (311)B InP substrates was performed under low-migration conditions to achieve good crystalline quality. The VCSEL was fabricated by wafer bonding, which enables us to combine different materials regardless of their lattice and orientation mismatch without degrading their quality. The VCSEL was polarized with a power extinction ratio of 31 dB.

A Test of Maxwell's Z Model Using Inverse Modeling

NASA Technical Reports Server (NTRS)

Anderson, J. L. B.; Schultz, P. H.; Heineck, T.

2003-01-01

In modeling impact craters a small region of energy and momentum deposition, commonly called a "point source", is often assumed. This assumption implies that an impact is the same as an explosion at some depth below the surface. Maxwell's Z Model, an empirical point-source model derived from explosion cratering, has previously been compared with numerical impact craters with vertical incidence angles, leading to two main inferences. First, the flowfield center of the Z Model must be placed below the target surface in order to replicate numerical impact craters. Second, for vertical impacts, the flow-field center cannot be stationary if the value of Z is held constant; rather, the flow-field center migrates downward as the crater grows. The work presented here evaluates the utility of the Z Model for reproducing both vertical and oblique experimental impact data obtained at the NASA Ames Vertical Gun Range (AVGR). Specifically, ejection angle data obtained through Three-Dimensional Particle Image Velocimetry (3D PIV) are used to constrain the parameters of Maxwell's Z Model, including the value of Z and the depth and position of the flow-field center via inverse modeling.

The influence of land use on the concentration and vertical distribution of PBDEs in soils of an e-waste recycling region of South China.

PubMed

Cheng, Zhineng; Wang, Yan; Wang, Shaorui; Luo, Chunling; Li, Jun; Chaemfa, Chakra; Jiang, Haoyu; Zhang, Gan

2014-08-01

The vertical distribution of polybrominated diphenyl ethers (PBDEs) in soil at four sites within an e-waste recycling region of South China was investigated. PBDE concentrations in soil ranged from 1.38 to 765 ng/g. There was a trend of decreasing PBDE concentration with soil depth, especially in the paddy field. However, high concentrations of BDE-209 were found in deeper soils indicating a highly preferential migration. There was a stronger correlation between PBDEs and total organic carbon (TOC), compared to dissolved organic carbon (DOC), which suggests that the association between non-dissolved organic carbon (NDOC) and PBDEs is stronger than for DOC. Different land use types, in particular differences in farming activities, significantly influenced the vertical distribution of PBDEs in soils. PBDEs displayed a higher leaching tendency in moist paddy soil than in drier soils. The frequent flooding condition in paddy field may facilitate the vertical transfer of PBDEs to the deeper soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

Prior exposure influences the behavioural avoidance by an intertidal gastropod, Bembicium auratum, of acidified waters

NASA Astrophysics Data System (ADS)

Amaral, Valter; Cabral, Henrique N.; Bishop, Melanie J.

2014-01-01

Phenotypic plasticity may be critical to the maintenance of viable populations under future environmental change. Here we examined the role of behavioural avoidance of sub-optimal conditions in enabling the intertidal gastropod, Bembicium auratum, to persist in mangrove forests affected by the low pH runoff from acid sulphate soils (ASS). Behaviourally, the gastropod may be able to avoid periods of particularly high acidity by using pneumatophores and/or mangrove trunks to vertically migrate above the water line or by retreating into its shell. We hypothesised that (1) B. auratum would display greater and more rapid vertical migration out of acidified than reference estuarine waters, and (2) responses would be more pronounced in gastropods collected from acidified than reference sites. Gastropods from acidified sites showed significantly higher activity in and more rapid migration out of acidified waters of pH 6.2-7.0, than reference waters or waters of pH < 5.0. Gastropods from reference locations showed a significantly weaker response to acidified water than those from acidified waters, and which did not significantly differ from their response to reference water. At extremely low pHs, <5.0, a higher proportion of both acidified and reference gastropods retreated into their shell than at higher pHs. Both the migration of gastropods out of acidified waters and retraction into their shells serves to reduce exposure time to acidified waters and may reduce the impact of this stressor on their populations. The stronger response to acidification of gastropods from populations previously exposed to this stressor suggests that the response may be learned, inherited or induced over multiple exposures. Our study adds to growing evidence that estuarine organisms may exhibit considerable physiological and behaviour adaptive capacity to acidification. The potential for such adaptive capacity should be incorporated into studies seeking to forecast impacts to marine organisms of environmental change.

The Genesis of the Milky Way's Thick Disk via Stellar Migration

NASA Astrophysics Data System (ADS)

Loebman, Sarah; Roskar, R.; Debattista, V. P.; Ivezic, Z.; Quinn, T. R.; Wadsley, J.

2011-01-01

The separation of the Milky Way disk into a thin and thick component is supported by differences in kinematics and metallicity. These differences have lead to the predominant view that the thick disk formed early via a cataclysmic event and constitutes fossil evidence of the hierarchical growth of the Milky Way. We show here, using N-body simulations, how a double vertical structure, with stellar populations displaying similar dichotomies can arise purely through internal evolution. Stars migrate radially, while retaining nearly circular orbits, as described by Sellwood & Binney (2002). As stars move outwards their vertical motions carry them to larger heights above the mid-plane, populating a thickened component. Such stars found at present time in the solar neighborhood formed early in the disk’s history at smaller radii where stars are more metal-poor and α-enhanced, leading to exactly the properties observed for thick disk stars. Classifying stars as members of the thin or thick disk by either velocity or metallicity leads to an apparent separation in the other property as observed. This scenario is supported by the SDSS observation that stars in the transition region do not show any correlation between rotation and metallicity. Such a correlation is present in young stars and arises because of epicyclic motions but migration radially mixes stars, washing out the correlation. Using the Geneva Copenhagen Survey, we indeed find a velocity-metallicity correlation in the younger stars and none in the older stars. We predict a similar result when separating stars by [α/Fe]. The good qualitative agreement between our simulation and observations are remarkable because the simulation was not tuned to reproduce the Milky Way, hinting that the thick disk may be dominated by stellar migration. Nonetheless, we cannot exclude that some fraction of the thick disk is a fossil of a past more violent history.

Impacts of hypoxia on the structure and processes in the pelagic community (zooplankton, macro-invertebrates and fish)

NASA Astrophysics Data System (ADS)

Ekau, W.; Auel, H.; Pörtner, H.-O.; Gilbert, D.

2009-05-01

Dissolved oxygen (DO) concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 ml L-1 and show impact on growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 ml L-1. A change in the average or the minimum or maximum DO in an area may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity. Evidence of the deleterious effects of oxygen depletion on species of the pelagic realm is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with different DOs and find adaptive mechanisms, nektonic species may avoid areas of inconvenient DO and develop adapted migrational strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ). In shallow areas only the surface layer can serve as a refuge, in deep waters many organisms have developed vertical migration strategies to use, pass and cope with the OMZ. This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity.

Vertical migration of fine-grained sediments from interior to surface of seabed driven by seepage flows-`sub-bottom sediment pump action'

NASA Astrophysics Data System (ADS)

Zhang, Shaotong; Jia, Yonggang; Wen, Mingzheng; Wang, Zhenhao; Zhang, Yaqi; Zhu, Chaoqi; Li, Bowen; Liu, Xiaolei

2017-02-01

A scientific hypothesis is proposed and preliminarily verified in this paper: under the driving of seepage flows, there might be a vertical migration of fine-grained soil particles from interior to surface of seabed, which is defined as `sub-bottom sediment pump action' in this paper. Field experiments were performed twice on the intertidal flat of the Yellow River delta to study this process via both trapping the pumped materials and recording the pore pressures in the substrate. Experimental results are quite interesting as we did observe yellow slurry which is mainly composed of fine-grained soil particles appearing on the seabed surface; seepage gradients were also detected in the intertidal flat, under the action of tides and small wind waves. Preliminary conclusions are that `sediment pump' occurs when seepage force exceeds a certain threshold: firstly, it is big enough to disconnect the soil particles from the soil skeleton; secondly, the degree of seabed fluidization or bioturbation is big enough to provide preferred paths for the detached materials to migrate upwards. Then they would be firstly pumped from interior to the surface of seabed and then easily re-suspended into overlying water column. Influential factors of `sediment pump' are determined as hydrodynamics (wave energy), degree of consolidation, index of bioturbation (permeability) and content of fine-grained materials (sedimentary age). This new perspective of `sediment pump' may provide some implications for the mechanism interpretation of several unclear geological phenomena in the Yellow River delta area.

The influence of spatially and temporally varying oceanographic conditions on meroplanktonic metapopulations

NASA Astrophysics Data System (ADS)

Botsford, L. W.; Moloney, C. L.; Hastings, A.; Largier, J. L.; Powell, T. M.; Higgins, K.; Quinn, J. F.

We synthesize the results of several modelling studies that address the influence of variability in larval transport and survival on the dynamics of marine metapopulations distributed along a coast. Two important benthic invertebrates in the California Current System (CCS), the Dungeness crab and the red sea urchin, are used as examples of the way in which physical oceanographic conditions can influence stability, synchrony and persistence of meroplanktonic metapopulations. We first explore population dynamics of subpopulations and metapopulations. Even without environmental forcing, isolated local subpopulations with density-dependence can vary on time scales roughly twice the generation time at high adult survival, shifting to annual time scales at low survivals. The high frequency behavior is not seen in models of the Dungeness crab, because of their high adult survival rates. Metapopulations with density-dependent recruitment and deterministic larval dispersal fluctuate in an asynchronous fashion. Along the coast, abundance varies on spatial scales which increase with dispersal distance. Coastwide, synchronous, random environmental variability tends to synchronize these metapopulations. Climate change could cause a long-term increase or decrease in mean larval survival, which in this model leads to greater synchrony or extinction respectively. Spatially managed metapopulations of red sea urchins go extinct when distances between harvest refugia become greater than the scale of larval dispersal. All assessments of population dynamics indicate that metapopulation behavior in general dependes critically on the temporal and spatial nature of larval dispersal, which is largely determined by physical oceanographic conditions. We therfore explore physical influences on larval dispersal patterns. Observed trends in temperature and salinity applied to laboratory-determined responses indicate that natural variability in temperature and salinity can lead to variability in larval development period on interannual (50%), intra-annual (20%) and latitudinal (200%) scales. Variability in development period significantly influences larval survival and, thus, net transport. Larval drifters that undertake diel vertical migration in a primitive equation model of coastal circulation (SPEM) demonstrate the importance of vertical migration in determining horizontal transport. Empirically derived estimates of the effects of wind forcing on larval transport of vertically migrating larvae (wind drift when near the surface and Ekman transport below the surface) match cross-shelf distributions in 4 years of existing larval data. We use a one-dimensional advection-diffusion model, which includes intra-annual timing of cross-shelf flows in the CCS, to explore the combined effects on settlement: (1) temperature- and salinity-dependent development and survival rates and (2) possible horizontal transport due to vertical migration of crab larvae. Natural variability in temperature, wind forcing, and the timing of the spring transition can cause the observed variability in recruitment. We conclude that understanding the dynamics of coastally distributed metapopulations in response to physically-induced variability in larval dispersal will be a critical step in assessing the effects of climate change on marine populations.

KSC-98pc505

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system.

KSC-98PC501

NASA Image and Video Library

1998-04-17

Framed by native Floridian foliage, the Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98dc496

NASA Image and Video Library

1998-04-17

The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc506

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia lifts off from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc508

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- STS-90 Mission Specialist Dafydd (Dave) Williams, M.D., with the Canadian Space Agency is assisted by NASA and United Space Alliance closeout crew members immediately preceding launch for the nearly 17-day Neurolab mission. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. Seen behind Williams also in an orange launch and re-entry suit is Mission Specialist Richard Linnehan, D.V.M. Williams and six fellow crew members will shortly enter the orbiter at KSC's Launch Pad 39B, where the Space Shuttle Columbia will lift off during a launch window that opens at 2:19 p.m. EDT, April 17

KSC-98pc499

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc516

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc502

NASA Image and Video Library

1998-04-17

Framed by native Floridian foliage, the Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc491

NASA Image and Video Library

1998-04-17

STS-90 Mission Specialist Richard Linnehan, D.V.M., sits in a chair during suitup activities in the Operations and Checkout Building. Linnehan and the rest of the STS-90 crew will shortly depart for Launch Pad 39B, where the Space Shuttle Columbia awaits a second liftoff attempt at 2:19 p.m. EDT. His second trip into space, Linnehan is participating in a life sciences research flight that will focus on the most complex and least understood part of the human body the nervous system. Neurolab will examine the effects of spaceflight on the brain, spinal cord, peripheral nerves and sensory organs in the human body

KSC-98pc498

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98dc497

NASA Image and Video Library

1998-04-17

The Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

Use of alumni and employer surveys for internal quality assurance of the DVM program at the University of Montreal.

PubMed

Doucet, Michèle Y; Vrins, André

2010-01-01

Annual alumni and employer surveys, initially designed as outcomes assessment tools, were integrated into a new internal quality assurance strategy to improve the doctor of veterinary medicine program at the University of Montreal's Faculté de Médecine Vétérinaire. Data collected annually from the classes of 2004-2007 indicated that alumni and their employers were generally satisfied with their level of preparation after one year of professional activity. Specific weaknesses were found in non-technical skills such as communication and resource management. These data were used in support of other forms of feedback to guide curricular reform.

From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part II Benthopelagic fishes

NASA Astrophysics Data System (ADS)

Denda, Anneke; Stefanowitsch, Benjamin; Christiansen, Bernd

2017-12-01

Specific mechanisms, driving trophic interactions between seamount associated fishes and the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure and the main prey of benthopelagic fishes from the summit and slope regions of Ampère and Senghor, two shallow seamounts in the subtropical and tropical NE Atlantic, and the adjacent deep-sea plains. For the identification of food sources and nutritional links to the pelagic realm a combination of stomach content and stable isotope ratio (δ13C and δ15N) analyses was used. δ13C ranged from -22.2‰ to -15.4‰ and δ15N covered a total range of 8.0-15.9‰. Feeding types of fish species comprised mainly zooplanktivores and mixed feeders, but also benthivores, piscivores, and predator-scavengers. Based on epipelagic particulate organic matter, they occupied trophic positions between the 2nd and 4th trophic level. Differences in stomach contents and stable isotope signatures indicate a resource partitioning among the benthopelagic fish fauna through distinct habitat choice, vertical feeding positions and prey selection. Topographic trapping of vertically migrating zooplankton on the summit seemed to be of minor importance for food supply of the resident near-bottom fishes, rather horizontal current-driven advection of the planktonic prey was assumed as major factor. Vertically migrating micronekton and mesopelagic fishes show up as key players within the food webs at Ampère and Senghor Seamounts and the adjacent deep-sea plains.

Effects of seasonal operation on the quality of water produced by public-supply wells

USGS Publications Warehouse

Bexfield, Laura M.; Jurgens, Bryant C.

2014-01-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.

Effects of Seasonal Operation on the Quality of Water Produced by Public-Supply Wells

PubMed Central

Bexfield, Laura M; Jurgens, Bryant C

2014-01-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin. PMID:24593780

Modeling Studies to Constrain Fluid and Gas Migration Associated with Hydraulic Fracturing Operations

NASA Astrophysics Data System (ADS)

Rajaram, H.; Birdsell, D.; Lackey, G.; Karra, S.; Viswanathan, H. S.; Dempsey, D.

2015-12-01

The dramatic increase in the extraction of unconventional oil and gas resources using horizontal wells and hydraulic fracturing (fracking) technologies has raised concerns about potential environmental impacts. Large volumes of hydraulic fracturing fluids are injected during fracking. Incidents of stray gas occurrence in shallow aquifers overlying shale gas reservoirs have been reported; whether these are in any way related to fracking continues to be debated. Computational models serve as useful tools for evaluating potential environmental impacts. We present modeling studies of hydraulic fracturing fluid and gas migration during the various stages of well operation, production, and subsequent plugging. The fluid migration models account for overpressure in the gas reservoir, density contrast between injected fluids and brine, imbibition into partially saturated shale, and well operations. Our results highlight the importance of representing the different stages of well operation consistently. Most importantly, well suction and imbibition both play a significant role in limiting upward migration of injected fluids, even in the presence of permeable connecting pathways. In an overall assessment, our fluid migration simulations suggest very low risk to groundwater aquifers when the vertical separation from a shale gas reservoir is of the order of 1000' or more. Multi-phase models of gas migration were developed to couple flow and transport in compromised wellbores and subsurface formations. These models are useful for evaluating both short-term and long-term scenarios of stray methane release. We present simulation results to evaluate mechanisms controlling stray gas migration, and explore relationships between bradenhead pressures and the likelihood of methane release and transport.

Acoustics Reveals the Presence of a Macrozooplankton Biocline in the Bay of Biscay in Response to Hydrological Conditions and Predator-Prey Relationships

PubMed Central

Lezama-Ochoa, Ainhoa; Irigoien, Xabier; Chaigneau, Alexis; Quiroz, Zaida; Lebourges-Dhaussy, Anne; Bertrand, Arnaud

2014-01-01

Bifrequency acoustic data, hydrological measurements and satellite data were used to study the vertical distribution of macrozooplankton in the Bay of Biscay in relation to the hydrological conditions and fish distribution during spring 2009. The most noticeable result was the observation of a ‘biocline’ during the day i.e., the interface where zooplankton biomass changes more rapidly with depth than it does in the layers above or below. The biocline separated the surface layer, almost devoid of macrozooplankton, from the macrozooplankton-rich deeper layers. It is a specific vertical feature which ties in with the classic diel vertical migration pattern. Spatiotemporal correlations between macrozooplankton and environmental variables (photic depth, thermohaline vertical structure, stratification index and chlorophyll-a) indicate that no single factor explains the macrozooplankton vertical distribution. Rather a set of factors, the respective influence of which varies from region to region depending on the habitat characteristics and the progress of the spring stratification, jointly influence the distribution. In this context, the macrozooplankton biocline is potentially a biophysical response to the search for a particular depth range where light attenuation, thermohaline vertical structure and stratification conditions together provide a suitable alternative to the need for expending energy in reaching deeper water without the risk of being eaten. PMID:24505374

Robbing Peter to Pay Paul: Modeling the Dynamic Evolution of the Coastal Carbon Sink Across Multiple Landforms

NASA Astrophysics Data System (ADS)

Herbert, E. R.; Walters, D.; Windham-Myers, L.; Kirwan, M. L.

2016-12-01

Evaluating the strength and long-term stability of the coastal carbon sink requires a consideration of the spatial evolution of coastal landscapes in both the horizontal and vertical dimensions. We present a model of the transformation and burial of carbon along a bay-marsh-upland forest complex to explore the response of the coastal carbon sink to sea level rise (SLR) and anthropogenic activity. We establish a carbon mass-balance by coupling dynamic biogeochemically-based models of soil carbon burial in aquatic, intertidal, and upland environments with a physically-based model of marsh edge erosion, vertical growth and migration into adjacent uplands. The modeled increase in marsh vertical growth and carbon burial at moderate rates of sea level rise (3-10 mm/yr) is consistent with a synthesis of 219 field measurements of marsh carbon accumulation that show a significant (p<0.0001) positive correlation with local SLR rates. The model suggests that at moderate SLR rates in low topographic relief landscapes, net marsh expansion into upland forest concomitant with increased carbon burial rates are sufficient to mitigate the associated loss of forest carbon stocks. Coastlines with high relief or barriers to wetland migration can become sources of carbon through the erosion of buried carbon stocks, but we show that the recapture of eroded carbon through vertical growth can be an important mechanism for reducing carbon loss. Overall, we show that the coastal carbon balance must be evaluated in a landscape context to account for changes in the size and magnitude of both the stocks and sinks of marsh carbon and for the transfers of carbon between coastal habitats. These results may help inform current efforts to appraise coastal carbon sinks that are beset by issues of landscape heterogeneity and the provenance of buried carbon.

Diel feeding behavior and ingestion rate in the copepod Calanus finmarchicus in the southern Gulf of Maine during late spring

NASA Astrophysics Data System (ADS)

Durbin, Edward G.; Campbell, Robert G.; Gilman, Sharon L.; Durbin, Ann G.

In situ feeding was measured on late stage Calanus finmarchicus in the southern Gulf of Maine during late spring 1988 and 1989. The region is a spring feeding ground for the planktivorous right whale, Eubalaena glacialis. Measurements in 1988 were made during the declining spring bloom, when phytoplankton showed considerable spatial variability. 1989 observations were made after summer stratification had become established, when phytoplankton biomass was low and dominated by the <7 μm size fraction. In situ ingestion rates of C. finmarchicus reflected these differences in food, and ranged from 30.2% body C day -1 at a spring bloom station to 0.6% body C day -1 after stratification. These values compare with a maximum ingestion rate of 44.3% body C day -1 measured in a shipboard grazing experiment using cultured algae as food, and indicate that C. finmarchicus became food limited in the southern Gulf of Maine after stratification. Calanus finmarchicus diet feeding behavior and diet vertical migration patterns changed during the seasonal progression from spring bloom to summer stratification. Diet feeding rhythms and vertical migration were absent during the bloom, but developed as the bloom declined. During the post-bloom stratified conditions, diet feeding rhythms continued but vertical migration ceased. Most of the C. finmarchicus population remained near the surface, while a small population of nonmigratory individuals resided at depth and appeared to be feeding upon sedimented spring bloom diatoms. At the spring bloom station C. finmarchicus ingested only a small proportion of the phytoplankton standing stock in the > 7 μm size fraction (2.9% day -1), reflecting the high biomass of phytoplankton and the stage composition of the C. finmarchicus population, dominated by early copepodite stages with low biomass. In contrast, at the post-bloom stations in 1989, the dense surface aggregations of C. finmarchicus populations were dominated by late copepodite stages whose total biomass was comparable to that of the phytoplankton, and C. finmarchicus consumed a significantly larger fraction of the > 7 μm phytoplankton standing crop (up to 62.5% day -1.

[Distribution and seasonal dynamics of meiofauna in intertidal zone of Qingdao sandy beaches, Shandong Province of East China].

PubMed

Li, Ha; Hua, Er; Zhang, Zhi-Nan

2012-12-01

An investigation was conducted on the abundance, group composition, and distribution of meiofauna at the Second Beach of Taiping Bay and the Shilaoren Beach in Qingdao in January, April, July, and October 2008, aimed to analyze the distribution and seasonal dynamics of meiofauna in the intertidal zone of Qingdao sandy beaches. The measurements of environmental factors, including sediment grain size, interstitial water salinity, interstitial water temperature, organic matter content (TOC), and chlorophyll a (Chl a) content, were made simultaneously. There existed obvious seasonal differences in the environment factors, which could be clustered into two groups, i. e. , spring-winter group (January and April) and summer-autumn group (July and October). At the Second Beach of Taiping Bay, the mean annual abundance of meiofauna was (1167.3 +/- 768.3) ind x 10 cm(-2), and the most dominant group was Nematoda, accounting for 91% of the total. The meiofaunal group composition and abundance at the Second Beach differed horizontally, with the abundance ranked as high tide zone < middle tide zone < low tide zone. The meiofaunal group composition and abundance also varied seasonally, with high values in spring/winter and low values in summer/autumn (spring > winter > autumn > summer). The vertical distribution of the meiofauna in the high and middle tide zones of the Second Beach varied seasonally too. The meiofauna migrated downward with increasing temperature, concentrated in surface layer in winter and migrated downward in summer. At the Shilaoren Beach, the mean annual abundance of meiofauna was (1130.2 +/- 1419.1) ind x 10 cm(-2), and Nematoda accounted for 85% of the total. There was a great similarity of the environmental factors in the middle tide zone of the Second Beach and Shilaoren Beach, which led to no differences in the meiofaunal group composition and abundance. However, the vertical distribution of the meiofauna differed between the two beaches. When the temperature decreased, the meiofauna at Shilaoren Beach migrated downward. The ANOVA and BIOENV analyses showed that the TOC and MD phi were most responsible for the distribution of meiofauna among the tidal zones, the interstitial water temperature, MD phi, and TOC were the main causes of the seasonal variation of meiofaunal group composition and abundance, whereas the sediment Chl a affected the vertical migration of meiofauna. Tourism-induced sediment variation was another factor affecting the meiofaunal abundance, group composition, and distribution.

Geochemical study of the organic matter from Querecual formation, Anzoategui State, Venezuela

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garban, G.; Lopez, L.; Lo Monaco, S.

1996-08-01

Kerogen and bitumen fractions extracted from twenty-one limestone samples from kind section of Querecual formation (Querecual River, Anzoategui State, Venezuela) were analyzed for their content of Co, Cr, Fe, Mn, Mo, Ni, S, Sr, V and Zn. S and trace-metals content from the kerogen fraction were used to obtain information about paleoenvironmental sedimentation conditions of the Querecual formation. Based on these data, and especially on the V and S content variations plus V/Ni, VIV+Ni and Mo/Mo+Cr ratios, we confirm an ancient-reducer condition on this region according with a sulfur-reducer environment. Trace-metals content variations from the bitumen fraction along the studymore » section were used as possible primary migration indicators. V and Ni were the only elements showing a clear tendency to be used as primary migration indicators. The observed tendency allows us to postulate a vertical migration of the bitumen, from center to the extremes of the section.« less

Oil prospects of Cuba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marrero-Faz, M.; Hernandezperez, G.

The Cuban Archipelago is an Early Tertiary thrust belt derived from the Collision of the Cretaceous volcanic arc from the South with the North American continental margin (Jurassic- Cretaceous). The main characteristics of the hydrocarbon potential of Cuba are: (1) Widespread existence of Jurassic-Cretaceous source rocks and active process of generation of different types of oils; (2) Hydrocarbons are reservoired in a wide range of rock types most commonly in thrusted, fractured carbonates of Jurassic to Cretaceous age. This kind of reservoir is the most important in Cuba; (3) High density in area of different types of traps, being themore » most important hinterland dipping thrust sheet play; and (4) Migration and trapping of hydrocarbons mainly in Eocene. Migration is supposed to be mostly lateral. Vertical migration is not excluded in the South and also in some part of the North Province. There still remains a significant number of untested, apparently valid exploration plays in both on- and offshore areas of Cuba.« less

Influence of local capillary trapping on containment system effectiveness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, Steven

2014-03-31

Immobilization of CO 2 injected into deep subsurface storage reservoirs is a critical component of risk assessment for geologic CO 2 storage (GCS). Local capillary trapping (LCT) is a recently established mode of immobilization that arises when CO 2 migrates due to buoyancy through heterogeneous storage reservoirs. This project sought to assess the amount and extent of LCT expected in storage formations under a range of injection conditions, and to confirm the persistence of LCT if the seal overlying the reservoir were to lose its integrity. Numerical simulation using commercial reservoir simulation software was conducted to assess the influence ofmore » injection. Laboratory experiments, modeling and numerical simulation were conducted to assess the effect of compromised seal integrity. Bench-scale (0.6 m by 0.6 m by 0.03 m) experiments with surrogate fluids provided the first empirical confirmation of the key concepts underlying LCT: accumulation of buoyant nonwetting phase at above residual saturations beneath capillary barriers in a variety of structures, which remains immobile under normal capillary pressure gradients. Immobilization of above-residual saturations is a critical distinction between LCT and the more familiar “residual saturation trapping.” To estimate the possible extent of LCT in a storage reservoir an algorithm was developed to identify all potential local traps, given the spatial distribution of capillary entry pressure in the reservoir. The algorithm assumes that the driving force for CO 2 migration can be represented as a single value of “critical capillary entry pressure” P c,entry crit, such that cells with capillary entry pressure greater/less than P c,entry crit act as barriers/potential traps during CO 2 migration. At intermediate values of P c,entry crit, the barrier regions become more laterally extensive in the reservoir, approaching a percolation threshold while non-barrier regions remain numerous. The maximum possible extent of LCT thus occurs at P c,entry crit near this threshold. Testing predictions of this simple algorithm against full-physics simulations of buoyancy-driven CO 2 migration support the concept of critical capillary entry pressure. However, further research is needed to determine whether a single value of critical capillary entry pressure always applies and how that value can be determined a priori. Simulations of injection into high-resolution (cells 0.3 m on a side) 2D and 3D heterogeneous domains show two characteristic behaviors. At small gravity numbers (vertical flow velocity much less than horizontal flow velocity) the CO 2 fills local traps as well as regions that would act as local barriers if CO 2 were moving only due to buoyancy. When injection ceases, the CO 2 migrates vertically to establish large saturations within local traps and residual saturation elsewhere. At large gravity numbers, the CO 2 invades a smaller portion of the perforated interval. Within this smaller swept zone the local barriers are not invaded, but local traps are filled to large saturation during injection and remain during post-injection gravity-driven migration. The small gravity number behavior is expected in the region within 100 m of a vertical injection well at anticipated rates of injection for commercial GCS. Simulations of leakage scenarios (through-going region of large permeability imposed in overlying seal) indicate that LCT persists (i.e. CO 2 remains held in a large fraction of the local iv traps) and the persistence is independent of injection rate during storage. Simulations of leakage for the limiting case of CO 2 migrating vertically from an areally extensive emplacement in the lower portion of a reservoir showed similar strong persistence of LCT. This research has two broad implications for GCS. The first is that LCT can retain a significant fraction of the CO 2 stored in a reservoir – above and beyond the residual saturation -- if the overlying seal were to fail. Thus frameworks for risk assessment should be extended to account for LCT. The second implication is that compared to pressure driven flow in reservoirs, CO 2 migration and trapping behave in a qualitatively different manner in heterogeneous reservoirs when buoyancy is the dominant driving force for flow. Thus simulations of GCS that neglect capillary heterogeneity will fail to capture important features of the CO 2 plume. While commercial reservoir simulation software can account for fine scale capillary heterogeneity, it has not been designed to work efficiently with such domains, and no simulators can handle fine-scale resolution throughout the reservoir. A possible way to upscale the migration and trapping is to apply an “effective residual saturation” to coarse-scale grids. While the extent of overall immobilization can be correlated in this way, all coarser grids failed to capture the distance traveled by the migrating CO 2 for large gravity number. Thus it remains unclear how best to account for LCT in the routine simulation work-flow that will be needed for large-scale GCS. Alternatives meriting investigation include streamline methods, reduced-physics proxies (e.g. particle tracking), and biased invasion percolation algorithms, which are based on precisely the capillary heterogeneity essential for LCT.« less

Synthetic seismic monitoring using reverse-time migration and Kirchhoff migration for CO2 sequestration in Korea

NASA Astrophysics Data System (ADS)

Kim, W.; Kim, Y.; Min, D.; Oh, J.; Huh, C.; Kang, S.

2012-12-01

During last two decades, CO2 sequestration in the subsurface has been extensively studied and progressed as a direct tool to reduce CO2 emission. Commercial projects such as Sleipner, In Salah and Weyburn that inject more than one million tons of CO2 per year are operated actively as well as test projects such as Ketzin to study the behavior of CO2 and the monitoring techniques. Korea also began the CCS (CO2 capture and storage) project. One of the prospects for CO2 sequestration in Korea is the southwestern continental margin of Ulleung basin. To monitor the behavior of CO2 underground for the evaluation of stability and safety, several geophysical monitoring techniques should be applied. Among various geophysical monitoring techniques, seismic survey is considered as the most effective tool. To verify CO2 migration in the subsurface more effectively, seismic numerical simulation is an essential process. Furthermore, the efficiency of the seismic migration techniques should be investigated for various cases because numerical seismic simulation and migration test help us accurately interpret CO2 migration. In this study, we apply the reverse-time migration and Kirchhoff migration to synthetic seismic monitoring data generated for the simplified model based on the geological structures of Ulleung basin in Korea. Synthetic seismic monitoring data are generated for various cases of CO2 migration in the subsurface. From the seismic migration images, we can investigate CO2 diffusion patterns indirectly. From seismic monitoring simulation, it is noted that while the reverse-time migration generates clear subsurface images when subsurface structures are steeply dipping, Kirchhoff migration has an advantage in imaging horizontal-layered structures such as depositional sediments appearing in the continental shelf. The reverse-time migration and Kirchhoff migration present reliable subsurface images for the potential site characterized by stratigraphical traps. In case of vertical CO2 migration at injection point, the reverse time migration yields better images than Kirchhoff migration does. On the other hand, Kirchhoff migration images horizontal CO2 migration clearer than the reverse time migration does. From these results, we can conclude that the reverse-time migration and Kirchhoff migration can complement with each other to describe the behavior of CO2 in the subsurface. Acknowledgement This work was financially supported by the Brain Korea 21 project of Energy Systems Engineering, the "Development of Technology for CO2 Marine Geological Storage" program funded by the Ministry of Land, Transport and Maritime Affairs (MLTM) of Korea and the Korea CCS R&D Center (KCRC) grant funded by the Korea government (Ministry of Education, Science and Technology) (No. 2012-0008926).

Spatial Dynamics of the Blue Crab Spawning Stock in the Gulf of Mexico: Local Processes Driving Regional Patterns.

NASA Astrophysics Data System (ADS)

Darnell, M. Z.

2016-02-01

Female blue crabs undertake a critical spawning migration seaward, migrating from low-salinity mating habitat to high-salinity waters of the lower estuaries and coastal ocean, where larval survival is highest. This migration occurs primarily through ebb tide transport, driven by an endogenous circatidal rhythm in vertical swimming that is modulated by behavioral responses to environmental cues. Blue crabs are typically considered an estuarine species and fisheries are managed on a state-by-state basis. Yet recent evidence from state and regional fishery independent survey programs suggests that the spawning migration can take females substantial distances offshore (>150 km), and that offshore waters are important spawning grounds for female blue crabs in the Gulf of Mexico. This is especially true in areas where freshwater inflow is high, resulting in low estuarine and coastal salinities. In low-salinity, high-inflow areas (e.g., Louisiana), spawning occurs further offshore while in high-salinity, low-inflow areas (e.g., South Texas), spawning takes place primarily within the estuary. Regional patterns in spawning locations both inshore and offshore are driven by interactions between behavioral mechanisms and local oceanographic conditions during the spawning migration. These environmentally driven differences in spawning locations have implications for larval survival and population connectivity, and emphasize the need for interjurisdictional assessment and management of the blue crab spawning stock.

The poleward migration of the location of tropical cyclone maximum intensity.

PubMed

Kossin, James P; Emanuel, Kerry A; Vecchi, Gabriel A

2014-05-15

Temporally inconsistent and potentially unreliable global historical data hinder the detection of trends in tropical cyclone activity. This limits our confidence in evaluating proposed linkages between observed trends in tropical cyclones and in the environment. Here we mitigate this difficulty by focusing on a metric that is comparatively insensitive to past data uncertainty, and identify a pronounced poleward migration in the average latitude at which tropical cyclones have achieved their lifetime-maximum intensity over the past 30 years. The poleward trends are evident in the global historical data in both the Northern and the Southern hemispheres, with rates of 53 and 62 kilometres per decade, respectively, and are statistically significant. When considered together, the trends in each hemisphere depict a global-average migration of tropical cyclone activity away from the tropics at a rate of about one degree of latitude per decade, which lies within the range of estimates of the observed expansion of the tropics over the same period. The global migration remains evident and statistically significant under a formal data homogenization procedure, and is unlikely to be a data artefact. The migration away from the tropics is apparently linked to marked changes in the mean meridional structure of environmental vertical wind shear and potential intensity, and can plausibly be linked to tropical expansion, which is thought to have anthropogenic contributions.

Deformation and Oil Migration Along the Active Newport-Inglewood Fault Zone, Southern California, USA

NASA Astrophysics Data System (ADS)

Sample, J. C.

2006-12-01

Deformation bands occur in an outcrop of a petroleum-bearing, sandstone-rich unit of the Monterey Formation along the active Newport-Inglewood fault zone (NIFZ), near Corona del Mar, California. The deformation bands likely developed in a damage zone associated with a strand of the NIFZ. The bands appear to have formed in poorly lithified sandstone. They are relatively oil-free whereas the matrix sandstone contains oil in pore space. The deformation bands acted as baffles to flow, but continuing deformation likely breached permeability barriers over time. Thus the bands did not completely isolate compartments from oil migration, but similar structures in the subsurface would likely slow the rate of production in reservoirs. The network of bands at Corona del Mar forms a mesh with band intersection lines lying parallel to the trend of the NIFZ (northwest). This geometry formed as continuing deformation in the NIFZ rotated early bands into unfavorable orientations for continuing deformation, and new bands formed at high angles to the first set. Permeability in this setting is likely to have been anisotropic, higher parallel to strike of the NIFZ and lower vertically and perpendicular to the strike of the fault zone. One unique type of deformation band found here formed by dilation and early oil migration along fractures, and consequent carbonate cementation along fracture margins. These are thin, planar zones of oil 1 - 2 mm thick sandwiched between parallel, carbonate-cemented, positively weathering ribs. These bands appear to represent early oil migration by hydrofracture. Based on crosscutting relationships between structures and cements, there are three distinct phases of oil migration: early migration along discrete hydrofractures; dominant pore migration associated with periodic breaching of deformation bands; and late migration along open fractures, some several centimeters in width. This sequence may be representative of migration histories along the NIFZ in the Los Angeles basin.

Nonlinear Boltzmann equation for the homogeneous isotropic case: Minimal deterministic Matlab program

NASA Astrophysics Data System (ADS)

Asinari, Pietro

2010-10-01

The homogeneous isotropic Boltzmann equation (HIBE) is a fundamental dynamic model for many applications in thermodynamics, econophysics and sociodynamics. Despite recent hardware improvements, the solution of the Boltzmann equation remains extremely challenging from the computational point of view, in particular by deterministic methods (free of stochastic noise). This work aims to improve a deterministic direct method recently proposed [V.V. Aristov, Kluwer Academic Publishers, 2001] for solving the HIBE with a generic collisional kernel and, in particular, for taking care of the late dynamics of the relaxation towards the equilibrium. Essentially (a) the original problem is reformulated in terms of particle kinetic energy (exact particle number and energy conservation during microscopic collisions) and (b) the computation of the relaxation rates is improved by the DVM-like correction, where DVM stands for Discrete Velocity Model (ensuring that the macroscopic conservation laws are exactly satisfied). Both these corrections make possible to derive very accurate reference solutions for this test case. Moreover this work aims to distribute an open-source program (called HOMISBOLTZ), which can be redistributed and/or modified for dealing with different applications, under the terms of the GNU General Public License. The program has been purposely designed in order to be minimal, not only with regards to the reduced number of lines (less than 1000), but also with regards to the coding style (as simple as possible). Program summaryProgram title: HOMISBOLTZ Catalogue identifier: AEGN_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGN_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License No. of lines in distributed program, including test data, etc.: 23 340 No. of bytes in distributed program, including test data, etc.: 7 635 236 Distribution format: tar.gz Programming language: Tested with Matlab version ⩽6.5. However, in principle, any recent version of Matlab or Octave should work Computer: All supporting Matlab or Octave Operating system: All supporting Matlab or Octave RAM: 300 MBytes Classification: 23 Nature of problem: The problem consists in integrating the homogeneous Boltzmann equation for a generic collisional kernel in case of isotropic symmetry, by a deterministic direct method. Difficulties arise from the multi-dimensionality of the collisional operator and from satisfying the conservation of particle number and energy (momentum is trivial for this test case) as accurately as possible, in order to preserve the late dynamics. Solution method: The solution is based on the method proposed by Aristov (2001) [1], but with two substantial improvements: (a) the original problem is reformulated in terms of particle kinetic energy (this allows one to ensure exact particle number and energy conservation during microscopic collisions) and (b) a DVM-like correction (where DVM stands for Discrete Velocity Model) is adopted for improving the relaxation rates (this allows one to satisfy exactly the conservation laws at macroscopic level, which is particularly important for describing the late dynamics in the relaxation towards the equilibrium). Both these corrections make possible to derive very accurate reference solutions for this test case. Restrictions: The nonlinear Boltzmann equation is extremely challenging from the computational point of view, in particular for deterministic methods, despite the increased computational power of recent hardware. In this work, only the homogeneous isotropic case is considered, for making possible the development of a minimal program (by a simple scripting language) and allowing the user to check the advantages of the proposed improvements beyond Aristov's (2001) method [1]. The initial conditions are supposed parameterized according to a fixed analytical expression, but this can be easily modified. Running time: From minutes to hours (depending on the adopted discretization of the kinetic energy space). For example, on a 64 bit workstation with Intel CoreTM i7-820Q Quad Core CPU at 1.73 GHz and 8 MBytes of RAM, the provided test run (with the corresponding binary data file storing the pre-computed relaxation rates) requires 154 seconds. References:V.V. Aristov, Direct Methods for Solving the Boltzmann Equation and Study of Nonequilibrium Flows, Kluwer Academic Publishers, 2001.

LOCO: Characterization of Phytoplankton in Thin Optical Layers

DTIC Science & Technology

2010-09-30

NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND...ADDRESS(ES) University of Rhode Island,Graduate School of Oceanography,South Ferry Road,Narragansett,RI,02882-1197 8. PERFORMING ORGANIZATION REPORT...population was superimposed on a diverse background of other planktonic organisms , some of which also underwent vertical migration, and others (e.g

Can Vertical Migrations of Dinoflagellates Explain Observed Bioluminescence Patterns During an Upwelling Event in Monterey Bay, California?

DTIC Science & Technology

2012-01-25

concentration of their population , physical con- ditions (currents, temperature, strength of stratification , mixed layer depth etc.), light...REPORT DOCUMENTATION PAGE Form Approved OMB No. 07040188 The public reporting burden for this collection of information is estimated to average 1...completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of

Open Burn/Open Detonation (OBOD) Area Management Using Lime For Explosives Transformation And Metals Immobilization

DTIC Science & Technology

2012-01-01

14 Figure 7. The column study used to test treatment options and longevity by tracking pH in the leachate from the APG OD soil...during baseline characterization of the APG OD site. ............................................................. 39 Table 8. Runoff water and leachate ...et al. 2006). Off-site migration of explosives from OBOD area soils is possible through horizon- tal transport in surface water and vertical leachate

Vertical redistribution of zooplankton in an oligotrophic lake associated with reduction in ultraviolet radiation by wildfire smoke

NASA Astrophysics Data System (ADS)

Urmy, Samuel S.; Williamson, Craig E.; Leach, Taylor H.; Schladow, S. Geoffrey; Overholt, Erin P.; Warren, Joseph D.

2016-04-01

We used a natural experiment to test whether wildfire smoke induced changes in the vertical distribution of zooplankton in Lake Tahoe by decreasing incident ultraviolet radiation (UV). Fires have a variety of effects on aquatic ecosystems, but these impacts are poorly understood and have rarely been observed directly. UV is an important driver of zooplankton vertical migration, and wildfires may alter it over large spatial scales. We measured UV irradiance and the distribution of zooplankton on two successive days. On one day, smoke haze from a nearby wildfire reduced incident UV radiation by up to 9%, but not irradiance in the visible spectrum. Zooplankton responded by positioning themselves, on average, 4.1 m shallower in the lake. While a limited data set such as this requires cautious interpretation, our results suggest that smoke from wildfires can change the UV environment and distribution of zooplankton. This process may be important in drought-prone regions with increasingly frequent wildfires, and globally due to widespread biomass burning.

Apparatus for electrophoresis separation

DOEpatents

Anderson, Norman L.

1978-01-01

An apparatus is disclosed for simultaneously performing electrophoresis separations on a plurality of slab gels containing samples of protein, protein subunits or nucleic acids. A reservoir of buffer solution is divided into three compartments by two parallel partitions having vertical slots spaced along their length. A sheet of flexible, electrically insulative material is attached to each partition and is provided with vertical slits aligned with the slots. Slab-gel holders are received within the slots with the flexible material folded outwardly as flaps from the slits to overlay portions of the holder surfaces and thereby act as electrical and liquid seals. An elongated, spaghetti-like gel containing a sample of specimen that was previously separated by isoelectric focusing techniques is vertically positioned along a marginal edge portion of the slab gel. On application of an electrical potential between the two outer chambers of buffer solution, a second dimensional electrophoresis separation in accordance with molecular weight occurs as the specimen molecules migrate across the slab gel.

Hydraulic properties of three types of glacial deposits in Ohio

USGS Publications Warehouse

Strobel, M.L.

1993-01-01

The effects of thickness, grain size, fractures, weathering, and atmosphericconditions on vertical ground-water flow in glacial deposits were studied at three sites that represent ground moraine, end moraine, and lacustrine depositional environments. Vertical hydraulic conductivities computed from pumped-well tests were 3.24 x 10-1 to 6.47 x 10-1 ft/d (feet per day) at the site representing end moraine and 1.17 ft/d at the site representing lacustrine deposits. Analysis of test data for the ground moraine site did not yield estimates of hydraulic conductivities, but did indicate that ground water flows through the total thickness of deposits in response to discharge from a lower gravel unit. Vertical hydraulic conductivities computed from pumped-well tests of nested wells and data from drill-core analyses indicate that fractures affect the migration of ground water downward through the glacial deposits at these sites. Flow through glacial deposits is complex; it is controlled by fractures, gram-size distribution, clay content, thickness, and degree of weathering, and atmospheric conditions.

Tracking the Subsurface Signal of Decadal Climate Warming to Quantify Vertical Groundwater Flow Rates

NASA Astrophysics Data System (ADS)

Bense, V. F.; Kurylyk, B. L.

2017-12-01

Sustained ground surface warming on a decadal time scale leads to an inversion of thermal gradients in the upper tens of meters. The magnitude and direction of vertical groundwater flow should influence the propagation of this warming signal, but direct field observations of this phenomenon are rare. Comparison of temperature-depth profiles in boreholes in the Veluwe area, Netherlands, collected in 1978-1982 and 2016 provided such direct measurement. We used these repeated profiles to track the downward propagation rate of the depth at which the thermal gradient is zero. Numerical modeling of the migration of this thermal gradient "inflection point" yielded estimates of downward groundwater flow rates (0-0.24 m a-1) that generally concurred with known hydrogeological conditions in the area. We conclude that analysis of inflection point depths in temperature-depth profiles impacted by surface warming provides a largely untapped opportunity to inform sustainable groundwater management plans that rely on accurate estimates of long-term vertical groundwater fluxes.

Project VeSElkA: results of abundance analysis for HD 53929 and HD 63975

NASA Astrophysics Data System (ADS)

Ndiaye, M. L.; LeBlanc, F.; Khalack, V.

2018-03-01

Project VeSElkA (Vertical Stratification of Element Abundances) has been initiated with the aim to detect and study the vertical stratification of element abundances in the atmosphere of chemically peculiar stars. Abundance stratification occurs in hydrodynamically stable stellar atmospheres due to the migration of the elements caused by atomic diffusion. Two HgMn stars, HD 53929 and HD 63975 were selected from the VeSElkA sample and analysed with the aim to detect some abundance peculiarities employing the ZEEMAN2 code. We present the results of abundance analysis of HD 53929 and HD 63975 observed recently with the spectropolarimeter ESPaDOnS at Canada-France-Hawaii Telescope. Evidence of phosphorus vertical stratification was detected in the atmosphere of these two stars. In both cases, phosphorus abundance increases strongly towards the superficial layers. The strong overabundance of Mn found in stellar atmosphere of both stars confirms that they are HgMn type stars.

Landsat-based Analysis of Mountain Forest-tundra Ecotone Response to Climate Trends in Sayan Mountains

NASA Technical Reports Server (NTRS)

Kharuk, Viatcheslav I.; Im, Sergey T.; Ranson, K. Jon

2007-01-01

observations of temperatures Siberia has shown a several degree warming over the past 30 years. It is expected that forest will respond to warming at high latitudes through increased tree growth and northward or upward slope migration. migration. Tree response to climate trends is most likely observable in the forest-tundra ecotone, where temperature mainly limits tree growth. Making repeated satellite observations over several decades provides an opportunity to track vegetation response to climate change. Based on Landsat data of the Sayan Mountains, Siberia, there was an increase in forest stand crown closure and an upward tree-line shift in the of the forest-tundra ecotone during the last quarter of the 2oth century,. On-ground observations, supporting these results, also showed regeneration of Siberian pine in the alpine tundra, and the transformation of prostrate Siberian pine and fir into arboreal (upright) forms. During this time period sparse stands transformed into closed stands, with existing closed stands increasing in area at a rate of approx. 1 %/yr, and advancing their upper border at a vertical rate of approx. 1.0 m/yr. In addition, the vertical rate of regeneration propagation is approx. 5 m/yr. It was also found that these changes correlated positively with temperature trends

Control of Diapause by Acidic pH and Ammonium Accumulation in the Hemolymph of Antarctic Copepods

PubMed Central

Schründer, Sabine; Schnack-Schiel, Sigrid B.; Auel, Holger; Sartoris, Franz Josef

2013-01-01

Life-cycles of polar herbivorous copepods are characterised by seasonal/ontogenetic vertical migrations and diapause to survive periods of food shortage during the long winter season. However, the triggers of vertical migration and diapause are still far from being understood. In this study, we test the hypothesis that acidic pH and the accumulation of ammonium (NH4 +) in the hemolymph contribute to the control of diapause in certain Antarctic copepod species. In a recent study, it was already hypothesized that the replacement of heavy ions by ammonium is necessary for diapausing copepods to achieve neutral buoyancy at overwintering depth. The current article extends the hypothesis of ammonium-aided buoyancy by highlighting recent findings of low pH values in the hemolymph of diapausing copepods with elevated ammonium concentrations. Since ammonia (NH3) is toxic to most organisms, a low hemolymph pH is required to maintain ammonium in the less toxic ionized form (NH4 +). Recognizing that low pH values are a relevant factor reducing metabolic rate in other marine invertebrates, the low pH values found in overwintering copepods might not only be a precondition for ammonium accumulation, but in addition, it may insure metabolic depression throughout diapause. PMID:24143238

Primary cilia maintain corneal epithelial homeostasis by regulation of the Notch signaling pathway

PubMed Central

Grisanti, Laura; Revenkova, Ekaterina; Gordon, Ronald E.

2016-01-01

Primary cilia have been linked to signaling pathways involved in cell proliferation, cell motility and cell polarity. Defects in ciliary function result in developmental abnormalities and multiple ciliopathies. Patients affected by severe ciliopathies, such as Meckel syndrome, present several ocular surface disease conditions of unclear pathogenesis. Here, we show that primary cilia are predominantly present on basal cells of the mouse corneal epithelium (CE) throughout development and in the adult. Conditional ablation of cilia in the CE leads to an increase in proliferation and vertical migration of basal corneal epithelial cells (CECs). A consequent increase in cell density of suprabasal layers results in a thicker than normal CE. Surprisingly, in cilia-deficient CE, cilia-mediated signaling pathways, including Hh and Wnt pathways, were not affected but the intensity of Notch signaling was severely diminished. Although Notch1 and Notch2 receptors were expressed normally, nuclear Notch1 intracellular domain (N1ICD) expression was severely reduced. Postnatal development analysis revealed that in cilia-deficient CECs downregulation of the Notch pathway precedes cell proliferation defects. Thus, we have uncovered a function of the primary cilium in maintaining homeostasis of the CE by balancing proliferation and vertical migration of basal CECs through modulation of Notch signaling. PMID:27122169

Modeled Tradeoffs between Developed Land Protection and Tidal Habitat Maintenance during Rising Sea Levels

PubMed Central

Cadol, Daniel; Elmore, Andrew J.; Guinn, Steven M.; Engelhardt, Katharina A. M.; Sanders, Geoffrey

2016-01-01

Tidal habitats host a diversity of species and provide hydrological services such as shoreline protection and nutrient attenuation. Accretion of sediment and biomass enables tidal marshes and swamps to grow vertically, providing a degree of resilience to rising sea levels. Even if accelerating sea level rise overcomes this vertical resilience, tidal habitats have the potential to migrate inland as they continue to occupy land that falls within the new tide range elevations. The existence of developed land inland of tidal habitats, however, may prevent this migration as efforts are often made to dyke and protect developments. To test the importance of inland migration to maintaining tidal habitat abundance under a range of potential rates of sea level rise, we developed a spatially explicit elevation tracking and habitat switching model, dubbed the Marsh Accretion and Inundation Model (MAIM), which incorporates elevation-dependent net land surface elevation gain functions. We applied the model to the metropolitan Washington, DC region, finding that the abundance of small National Park Service units and other public open space along the tidal Potomac River system provides a refuge to which tidal habitats may retreat to maintain total habitat area even under moderate sea level rise scenarios (0.7 m and 1.1 m rise by 2100). Under a severe sea level rise scenario associated with ice sheet collapse (1.7 m by 2100) habitat area is maintained only if no development is protected from rising water. If all existing development is protected, then 5%, 10%, and 40% of the total tidal habitat area is lost by 2100 for the three sea level rise scenarios tested. PMID:27788209

Modeled Tradeoffs between Developed Land Protection and Tidal Habitat Maintenance during Rising Sea Levels.

PubMed

Cadol, Daniel; Elmore, Andrew J; Guinn, Steven M; Engelhardt, Katharina A M; Sanders, Geoffrey

2016-01-01

Tidal habitats host a diversity of species and provide hydrological services such as shoreline protection and nutrient attenuation. Accretion of sediment and biomass enables tidal marshes and swamps to grow vertically, providing a degree of resilience to rising sea levels. Even if accelerating sea level rise overcomes this vertical resilience, tidal habitats have the potential to migrate inland as they continue to occupy land that falls within the new tide range elevations. The existence of developed land inland of tidal habitats, however, may prevent this migration as efforts are often made to dyke and protect developments. To test the importance of inland migration to maintaining tidal habitat abundance under a range of potential rates of sea level rise, we developed a spatially explicit elevation tracking and habitat switching model, dubbed the Marsh Accretion and Inundation Model (MAIM), which incorporates elevation-dependent net land surface elevation gain functions. We applied the model to the metropolitan Washington, DC region, finding that the abundance of small National Park Service units and other public open space along the tidal Potomac River system provides a refuge to which tidal habitats may retreat to maintain total habitat area even under moderate sea level rise scenarios (0.7 m and 1.1 m rise by 2100). Under a severe sea level rise scenario associated with ice sheet collapse (1.7 m by 2100) habitat area is maintained only if no development is protected from rising water. If all existing development is protected, then 5%, 10%, and 40% of the total tidal habitat area is lost by 2100 for the three sea level rise scenarios tested.

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

NASA Astrophysics Data System (ADS)

Ekau, W.; Auel, H.; Pörtner, H.-O.; Gilbert, D.

2010-05-01

Dissolved oxygen (DO) concentration in the water column is an environmental parameter that is crucial for the successful development of many pelagic organisms. Hypoxia tolerance and threshold values are species- and stage-specific and can vary enormously. While some fish species may suffer from oxygen values of less than 3 mL O2 L-1 through impacted growth, development and behaviour, other organisms such as euphausiids may survive DO levels as low as 0.1 mL O2 L-1. A change in the average or the range of DO may have significant impacts on the survival of certain species and hence on the species composition in the ecosystem with consequent changes in trophic pathways and productivity. Evidence for the deleterious effects of oxygen depletion on pelagic species is scarce, particularly in terms of the effect of low oxygen on development, recruitment and patterns of migration and distribution. While planktonic organisms have to cope with variable DOs and exploit adaptive mechanisms, nektonic species may avoid areas of unfavourable DO and develop adapted migration strategies. Planktonic organisms may only be able to escape vertically, above or beneath the Oxygen Minimum Zone (OMZ). In shallow areas only the surface layer can serve as a refuge, but in deep waters many organisms have developed vertical migration strategies to use, pass through and cope with the OMZ. This paper elucidates the role of DO for different taxa in the pelagic realm and the consequences of low oxygen for foodweb structure and system productivity. We describe processes in two contrasting systems, the semi-enclosed Baltic Sea and the coastal upwelling system of the Benguela Current to demonstrate the consequences of increasing hypoxia on ecosystem functioning and services.

Combining Bioenergetic Responses of Fish to Thermal Regimes and Productivity in Reservoirs: Implications for Conservation and Re-Introduction of Anadromous Salmonids

NASA Astrophysics Data System (ADS)

Beauchamp, D.

2014-12-01

Temperature, food availability, and predation risk form vertical gradients determining growth and survival for fish in lakes and reservoirs. These gradients change on inter-annual, seasonal, and diel temporal scales and are strongly influenced by climatic variability, conflicting water demands and management. Temperatures associated with optimal growth and energy loss vary both among life stages and species of fish, but the quantity and quality of available food resources can significantly alter these thermal responses. Greater understanding of how water management affects the timing, magnitude, and duration of thermal stratification, and how key species and their supporting aquatic resources respond can improve strategies for development and operation of water storage facilities within the context of localized environmental and ecological constraints. An emerging trend for coldwater reservoirs in the Pacific Northwest has been to re-introduce anadromous salmon above historically impassable dams. Thermal regimes and the existing ecological communities in the reservoirs and tributary habitats above these dams will determine the seasonal importance of lotic and lentic habitats for rearing or migration corridors. The feasibility of reservoir rearing and migration can be evaluated by combining mass- and species-specific thermal growth response curves with temporal dynamics in the vertical and longitudinal thermal structure of reservoirs and associated distribution of food resources (primarily zooplankton). The value of reservoirs as rearing habitats or migration corridors could be compared with coincident tributary conditions to predict the likely temporal-spatial distribution of optimal conditions for growth and survival of different species or life stages of salmonids within the watershed and how these conditions might change under different climatic or water management scenarios.

Assessment of brine migration along vertical pathways due to CO2 injection

NASA Astrophysics Data System (ADS)

Kissinger, Alexander; Class, Holger

2016-04-01

Global climate change, shortage of resources and the growing usage of renewable energy sources has lead to a growing demand for the utilization of subsurface systems which may create conflicts with essential public interests such as water supply from aquifers. For example, brine migration into potential drinking water aquifers due to the injection of CO2 into deep saline aquifers is perceived as a potential threat resulting from the Carbon Capture and Storage Technology (CCS). In this work, we focus on the large scale impacts of CO2 storage on brine migration but the methodology and the obtained results may also apply to other fields like waste water disposal, where large amounts of fluid are injected into the subsurface. We consider a realistic (but not real) on-shore site in the North German Basin with characteristic geological features. In contrast to modeling on the reservoir scale, the spatial scale in this work is much larger in both vertical and lateral direction, since the regional hydrogeology is considered as well. Structures such as fault zones, hydrogeological windows in the Rupelian clay or salt wall flanks are considered as potential pathways for displaced fluids into shallow systems and their influence needs to be taken into account. Simulations on this scale always require a compromise between the accuracy of the description of the relevant physical processes, data availability and computational resources. Therefore, we test different model simplifications and discuss them with respect to the relevant physical processes and the expected data availability. The simplifications in the models are concerned with the role of salt-induced density differences on the flow, with injection of brine (into brine) instead of CO2 into brine, and with simplifying the geometry of the site.

Late Miocene uplift in the Romagnan Apennines and the detachment of subducted lithosphere

NASA Astrophysics Data System (ADS)

van der Meulen, M. J.; Kouwenhoven, T. J.; van der Zwaan, G. J.; Meulenkamp, J. E.; Wortel, M. J. R.

1999-12-01

We report part of a test of the hypothesis that detachment of subducted lithosphere may be a process of lateral propagation of a horizontal tear [Wortel and Spakman, Proc. Kon. Ned. Akad. Wetensch., 95 (1992) 325-347]. We have used the Apennines as a test area. The test procedure consists of the comparison of hypothetical vertical motions, predicted from the expected redistribution of slab pull forces, with observed vertical motions. We demonstrate that a Late Miocene depocentre migration from the Northern towards the Central Apennines is associated with uplift of (the fore-arc of) the Northern Apennines. Such a combination of a depocentre shift and uplift is thought to be diagnostic for lateral migration of slab detachment. The depocentre migration was identified in earlier work [van der Meulen et al., Earth Planet. Sci. Lett., 154 (1998) 203-219]. This contribution focuses on uplift, which has primarily been identified through the geohistory analysis of the Monte del Casino Section (Romagnan Apennines, Northern Italy). Owing to methodological problems, the start and duration of the uplift phase could not be constrained, and only a minimum estimate of the total amount of uplift (483±180 m) is obtained. The data do allow for an estimate of the uplift rate: 163±61 cm/ky. A review of regional data results in better constraints on the timing of the above lateral reorganisation of the fore-arc, and on the spatial extent of the uplifted area. Depocentre development in the Central Apennines began between 8.6 and 8.3 Ma B.P. Uplift started between 9 and 8 Ma B.P., and affected the entire northernmost Apennines.

DDT Vertical Migration and Formation of Accumulation Layer in Pesticide-Producing Sites.

PubMed

Liu, Li; Bai, Liping; Man, Changgeng; Liang, Wuhong; Li, Fasheng; Meng, Xiaoguang

2015-08-04

Soil samples were collected at various depths (0.5-21.5 m) from ten boreholes that were drilled with a SH-30 Model Rig, four of which were at a dicofol production site while six were at a dichlorodiphenyltrichloroethane (DDT) production site. In industrial sites, the shallow soils at depths of 0-2 m were mostly backfill soils, which cannot represent the contamination situation of the sites. The contaminated levels in the deep original soil can represent the situation in contaminated sites. All the soil samples investigated at the DDT and dicofol production sites were found to be seriously polluted. The contents of both DDT (0.6-6071 mg/kg) and dicofol (0.5-1440 mg/kg) were much higher at the dicofol production site than at the DDT production site (DDTs, 0.01-664.6 mg/kg; dicofol, <0.1 mg/kg), even in the deep soil. DDTs had a different distribution in the soil of the pesticide production site from that in the soil outside the sites and that in agricultural soils. The results of the investigation revealed that DDTs were easily enriched in cohesive soil and in the bottom zone of aquifers, where the concentration was higher than in above the layers. DDTs were found to be hard to degrade, and their degradation speed was slower than their vertical migration, despite the fact that hydrophobic DDTs did not migrate easily in soils. In the dicofol production site, the value of DDE/DDD cannot indicate the degradation condition of DDTs, nor can the value of (DDE + DDD)/DDT identify how long DDTs have remained in the soil. It is debatable that the half-life of DDT inputted to soils is about 20-30 years, maybe longer than the generally recognized time.

Causes of the longitudinal differences in the equatorial vertical E × B drift during the 2013 SSW period as simulated by the TIME-GCM

NASA Astrophysics Data System (ADS)

Maute, A.; Hagan, M. E.; Yudin, V.; Liu, H.-L.; Yizengaw, E.

2015-06-01

During stratospheric sudden warming (SSW) periods large changes in the low-latitude vertical drift have been observed at Jicamarca as well as in other longitudinal sectors. In general, a strengthening of the daytime maximum vertical drift with a shift from prenoon to the afternoon is observed. During the January 2013 stratospheric warming significant longitudinal differences in the equatorial vertical drift were observed. At Jicamarca the previously reported SSW behavior prevails; however, no shift of the daytime maximum drift was exhibited in the African sector. Using the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) the possible causes for the longitudinal difference are examined. The timing of the strong SSW effect in the vertical drift (15-20 January) coincides with moderate geomagnetic activity. The simulation indicates that approximately half of the daytime vertical drift increase in the American sector may be related to the moderate geophysical conditions (Kp = 4) with the effect being negligible in the African sector. The simulation suggests that the wind dynamo accounts for approximately 50% of the daytime vertical drift in the American sector and almost 100% in the African sector. The simulation agrees with previous findings that the migrating solar tides and the semidiurnal westward propagating tide with zonal wave number 1 (SW1) mainly contribute to the daytime wind dynamo and vertical drift. Numerical experiments suggest that the neutral wind and the geomagnetic main field contribute to the presence (absence) of a local time shift in the daytime maximum drift in the American (African) sector.

Geodynamic modeling of the capture and release of a plume conduit by a migrating mid-ocean ridge

NASA Astrophysics Data System (ADS)

Hall, P. S.

2011-12-01

plates over the relatively stationary, long-lived conduits of mantle plumes. However, paleomagnetic data from the Hawaii-Emperor Seamount Chain suggests that the Hawaiian hotspot moved rapidly (~40 mm/yr) between 81 - 47 Ma [Tarduno et al., 2003]. Recently, Tarduno et al. [2009] suggested that this period of rapid motion might be the surface expression of a plume conduit returning to a largely vertical orientation after having been captured and tilted as the result of being "run over" by migrating mid-ocean ridge. I report on a series of analog geodynamic experiments designed to characterize the evolution of a plume conduit as a mid-ocean ridge migrates over. Experiments were conducted in a clear acrylic tank (100 cm x 70 cm x 50 cm) filled with commercial grade high-fructose corn syrup. Plate-driven flow is modeled by dragging two sheets of Mylar film (driven by independent DC motors) in opposite directions over the surface of the fluid. Ridge migration is achieved by moving the point at which the mylar sheets diverge using a separate motor drive. Buoyant plume flow is generated using a small electrical heater placed at the bottom of the tank. Plate velocities and ridge migration rate are controlled and plume temperature monitored using LabView software. Experiments are recorded using digital video which is then analyzed using digital image analysis software to track the position and shape of the plume conduit throughout the course of the experiment. The intersection of the plume conduit with the surface of the fluid is taken as an analog for the locus of hotspot volcanism and tracked as a function of time to obtain a hotspot migration rate. Results show that the plume conduit experiences significant tilting immediately following the passage of the migrating ridge.

Simulating the Oceanic Migration of Silver Japanese Eels

PubMed Central

Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

2016-01-01

The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s−1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s−1 for true navigation, 0.12 m s−1 for constant compass heading, and 0.35 m s−1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s−1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity. PMID:26982484

Simulating the Oceanic Migration of Silver Japanese Eels.

PubMed

Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

2016-01-01

The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s-1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s-1 for true navigation, 0.12 m s-1 for constant compass heading, and 0.35 m s-1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s-1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity.

Hydrocarbon Migration from the Micro to Macro Scale in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Johansen, C.; Marty, E.; Silva, M.; Natter, M.; Shedd, W. W.; Hill, J. C.; Viso, R. F.; Lobodin, V.; Krajewski, L.; Abrams, M.; MacDonald, I. R.

2016-02-01

In the Northern Gulf of Mexico (GoM) at GC600, ECOGIG has been investigating the processes involved in hydrocarbon migration from deep reservoirs to sea surface. We studied two individual vents, Birthday Candles (BC) and Mega-Plume (MP), which are separated by 1km on a salt supported ridge trending from NW-SE. Seismic data depicts two faults, also separated by 1km, feeding into the surface gas hydrate region. BC and MP comprise the range between oily, mixed, and gaseous-type vents. In both cases bubbles are observed escaping from gas hydrate out crops at the sea floor and supporting chemosynthetic communities. Fluid flow is indicated by features on the sea floor such as hydrate mounds, authigenic carbonates, brine pools, mud volcanoes, and biology. We propose a model to describe the upward flow of hydrocarbons from three vertical scales, each dominated by different factors: 1) macro (capillary failure in overlying cap rocks causing reservoir leakage), 2) meso (buoyancy driven fault migration), and 3) micro (hydrate formation and chemosynthetic activity). At the macro scale we use high reflectivity in seismic data and sediment pore throat radii to determine the formation of fractures in leaky reservoirs. Once oil and gas leave the reservoir through fractures in the cap rock they migrate in separate phases. At the meso scale we use seismic data to locate faults and salt diapirs that form conduits for buoyant hydrocarbons follow. This connects the path to the micro scale where we used video data to observe bubble release from individual vents for extended periods of time (3h-26d), and developed an image processing program to quantify bubble release rates. At mixed vents gaseous bubbles are observed escaping hydrate outcrops with a coating of oil varying in thickness. Bubble oil and gas ratios are estimated using average bubble size and release rates. The relative vent age can be described by carbonate hard ground cover, biological activity, and hydrate mound formation as these features progress with persistent hydrocarbon influx. Bottom features along with seismic data, bubble release rates and bubble composition (oily vs gaseous), are implemented into our model to describe the relative vent age and dynamic mechanisms of hydrocarbon migration at three vertical spatial scales of oily and gaseous natural seeps in the GoM.

Nonlinear Analysis of Two-phase Circumferential Motion in the Ablation Circumstance

NASA Astrophysics Data System (ADS)

Xiao-liang, Xu; Hai-ming, Huang; Zi-mao, Zhang

2010-05-01

In aerospace craft reentry and solid rocket propellant nozzle, thermal chemistry ablation is a complex process coupling with convection, heat transfer, mass transfer and chemical reaction. Based on discrete vortex method (DVM), thermal chemical ablation model and particle kinetic model, a computational module dealing with the two-phase circumferential motion in ablation circumstance is designed, the ablation velocity and circumferential field can be thus calculated. The calculated nonlinear time series are analyzed in chaotic identification method: relative chaotic characters such as correlation dimension and the maximum Lyapunov exponent are calculated, fractal dimension of vortex bulbs and particles distributions are also obtained, thus the nonlinear ablation process can be judged as a spatiotemporal chaotic process.

KSC-98pc504

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- Framed by native Floridian foliage, the Space Shuttle Columbia soars from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc579

NASA Image and Video Library

1998-05-03

Some of the STS-90 crew members pose at the Shuttle Landing Facility hours after arrival on May 3, ending their nearly 16-day Neurolab mission. Shown left to right are Mission Specialist Richard Linnehan, D.V.M.; Payload Specialist Jay Buckey, M.D.; and Mission Specialists Dafydd (Dave) Williams, M.D., with the Canadian Space Agency and Kathryn (Kay) Hire holding a sign that states "Proud to be at KSC." The 90th Shuttle mission was Columbia's 13th landing at the space center and the 43rd KSC landing in the history of the Space Shuttle program. During the mission, the crew conducted research to contribute to a better understanding of the human nervous system

KSC-98pc503

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia surges skyward from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. The launch was delayed 24 hours due to difficulty with a network signal processor, which was replaced Apr. 16, on the orbiter. The crew members on-board include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

KSC-98pc507

NASA Image and Video Library

1998-04-17

KENNEDY SPACE CENTER, FLA. -- The Space Shuttle Columbia lifts off from Launch Pad 39B at 2:19 p.m. EDT Apr. 17 to begin the nearly 17-day STS-90 Neurolab mission. A torrent of water is seen flowing onto the mobile launcher platform as several large quench nozzles, or "rainbirds," mounted on platform's surface operate as a sound suppression system. The crew members are Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., with the Canadian Space Agency, and Kathryn (Kay) Hire; and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system

Development of Vertical Cable Seismic System for Hydrothermal Deposit Survey (2) - Feasibility Study

NASA Astrophysics Data System (ADS)

Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Mikada, H.; Takekawa, J.; Shimura, T.

2010-12-01

In 2009, Ministry of Education, Culture, Sports, Science and Technology(MEXT) started the survey system development for Hydrothermal deposit. We proposed the Vertical Cable Seismic (VCS), the reflection seismic survey with vertical cable above seabottom. VCS has the following advantages for hydrothermal deposit survey. . (1) VCS is an effective high-resolution 3D seismic survey within limited area. (2) It achieves high-resolution image because the sensors are closely located to the target. (3) It avoids the coupling problems between sensor and seabottom that cause serious damage of seismic data quality. (4) Various types of marine source are applicable with VCS such as sea-surface source (air gun, water gun etc.) , deep-towed or ocean bottom sources. (5) Autonomous recording system. Our first experiment of 2D/3D VCS surveys has been carried out in Lake Biwa, JAPAN. in November 2009. The 2D VCS data processing follows the walk-away VSP, including wave field separation and depth migration. The result gives clearer image than the conventional surface seismic. Prestack depth migration is applied to 3D data to obtain good quality 3D depth volume. Uncertainty of the source/receiver poisons in water causes the serious problem of the imaging. We used several transducer/transponder to estimate these positions. The VCS seismic records themselves can also provide sensor position using the first break of each trace and we calibrate the positions. We are currently developing the autonomous recording VCS system and planning the trial experiment in actual ocean to establish the way of deployment/recovery and the examine the position through the current flow in November, 2010. The second VCS survey will planned over the actual hydrothermal deposit with deep-towed source in February, 2011.

Effects of seasonal operation on the quality of water produced by public-supply wells.

PubMed

Bexfield, Laura M; Jurgens, Bryant C

2014-09-01

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

Pleistocene vertical motions of the Costa Rican outer forearc from subducting topography and a migrating fracture zone triple junction

USGS Publications Warehouse

Edwards, Joel H.; Kluesner, Jared W.; Silver, Eli A.; Bangs, Nathan L.

2018-01-01

Understanding the links between subducting slabs and upper-plate deformation is a longstanding goal in the field of tectonics. New 3D seismic sequence stratigraphy, mapped within the Costa Rica Seismogenesis Project (CRISP) seismic-reflection volume offshore southern Costa Rica, spatiotemporally constrains several Pleistocene outer forearc processes and provides clearer connections to subducting plate dynamics. Three significant shelf and/or slope erosional events at ca. 2.5–2.3 Ma, 1.95–1.78 Ma, and 1.78–1.19 Ma, each with notable differences in spatial extent, volume removed, and subsequent margin response, caused abrupt shifts in sedimentation patterns and rates. These shifts, coupled with observed deformation, suggest three primary mechanisms for Pleistocene shelf and slope vertical motions: (1) regional subaerial erosion and rapid subsidence linked to the southeastward Panama Fracture Zone triple-junction migration, with associated abrupt bathymetric variations and plate kinematic changes; (2) transient, kilometer-scale uplift and subsidence due to inferred subducting plate topography; and (3) progressive outer wedge shortening accommodated by landward- and seaward-dipping thrust faults and fold development due to the impinging Cocos Ridge. Furthermore, we find that the present-day wedge geometry (to within ∼3 km along strike) has been maintained through the Pleistocene, in contrast to modeled landward margin retreat. We also observe that deformation, i.e., extension and shortening, is decoupled from net margin subsidence. Our findings do not require basal erosion, and they suggest that the vertical motions of the Costa Rican outer forearc are not the result of a particular continuous process, but rather are a summation of plate to plate changes (e.g., passage of a fracture zone triple junction) and episodic events (e.g., subducting plate topography).

Electrolyte matrix in a molten carbonate fuel cell stack

DOEpatents

Reiser, C.A.; Maricle, D.L.

1987-04-21

A fuel cell stack is disclosed with modified electrolyte matrices for limiting the electrolytic pumping and electrolyte migration along the stack external surfaces. Each of the matrices includes marginal portions at the stack face of substantially greater pore size than that of the central body of the matrix. Consequently, these marginal portions have insufficient electrolyte fill to support pumping or wicking of electrolyte from the center of the stack of the face surfaces in contact with the vertical seals. Various configurations of the marginal portions include a complete perimeter, opposite edge portions corresponding to the air plenums and tab size portions corresponding to the manifold seal locations. These margins will substantially limit the migration of electrolyte to and along the porous manifold seals during operation of the electrochemical cell stack. 6 figs.

Electrolyte matrix in a molten carbonate fuel cell stack

DOEpatents

Reiser, Carl A.; Maricle, Donald L.

1987-04-21

A fuel cell stack is disclosed with modified electrolyte matrices for limiting the electrolytic pumping and electrolyte migration along the stack external surfaces. Each of the matrices includes marginal portions at the stack face of substantially greater pore size than that of the central body of the matrix. Consequently, these marginal portions have insufficient electrolyte fill to support pumping or wicking of electrolyte from the center of the stack of the face surfaces in contact with the vertical seals. Various configurations of the marginal portions include a complete perimeter, opposite edge portions corresponding to the air plenums and tab size portions corresponding to the manifold seal locations. These margins will substantially limit the migration of electrolyte to and along the porous manifold seals during operation of the electrochemical cell stack.

Chemical Evidence for Vertical Transport from Magma Chambers to the Surface During Mid-Ocean Ridge Volcanic Eruptions

NASA Astrophysics Data System (ADS)

Sinton, J. M.; Rubin, K. H.

2009-12-01

Many mid-ocean ridge eruptions show significant internal chemical heterogeneity; in general, the amount of chemical heterogeneity within eruptions scales with erupted volume. These variations reflect magmatic processes occurring in magma reservoirs prior to or possibly during eruption. For example, systematic variations in Mg# with along-axis distance in the early 90’s Aldo-Kihi (S. EPR near 17.5°S), 1996 N. Gorda, 1993 Co-Axial (Juan de Fuca Ridge), and 1991-2 and 2005-6 9°50’N EPR eruptions is unlikely to be related to fractionation during emplacement, and rather reflects variations in sub-axial magma reservoirs prior to eruption. Such variations are inconsistent with well-mixed sub-axial reservoirs and, in some cases, require relatively long-lived, systematic variations in reservoir temperatures along axis. Chemical heterogeneity within the Aldo-Kihi eruption preserves spatial variations in mantle-derived isotopic and trace element ratios with implications for the temporal and spatial scales of magma injections to the crust and along-axis mixing within shallow reservoirs. These spatial variations are difficult to reconcile with significant (> ~1 km) along-axis magma transport, as are striking correlations of chemical compositions with surface geological discontinuities or seismically imaged sub-axial magma chamber reflectors in the S. Hump (S. EPR), 9°50’N EPR, N. Gorda and 1975-1984 Krafla (N. Iceland) eruptive units. Rather, spatial correlations between surface lava compositions and sub-axial magma chamber properties or long-lived axial morphology suggest that most of the erupted magma was transported nearly vertically from the underlying reservoirs to the surface during these eruptions. In the case of the Krafla eruption, coincident deformation suggests a component of lateral melt migration at depth, despite chemical evidence for vertical transport of erupted lava from more than one chemical reservoir. In addition, along-ridge movement of earthquake epicenters during the 1992 Co-Axial and 1996 Gorda eruptions implies migration of stress release during these eruptions, even though vertical transport better explains chemical patterns. The nature of transport for most eruptions is unclear because of lack of systematic chemical patterns; this presentation emphasizes those cases where vertical transport appears to be required.

New hydrologic model of fluid migration in deep porous media

NASA Astrophysics Data System (ADS)

Dmitrievsky, A.; Balanyuk, I.

2009-04-01

The authors present a new hydrological model of mantle processes that effect on formation of oil-and-gas bearing basins, fault tectonics and thermal convection. Any fluid migration is initially induced by lateral stresses in the crust and lithosphere which result from global geodynamic processes related to the mantle convection. The global processes are further transformed into regional movements in weakness zones. Model of porous media in deep fractured zones and idea of self-oscillation processes in mantle layers and fractured zones of the crust at different depths was used as the basis for developed concept. The content of these notions resides in the fact that there are conditions of dynamic balance in mantle layers originating as a result of combination and alternate actions of compaction and dilatance mechanisms. These mechanisms can be manifested in different combinations and under different conditions as well as can be complemented by other processes influencing on regime of fluid migration. They can act under condition of passive margin, ocean rift and ocean subduction zones as well as in consolidated platform and sheet. Self-oscillation regime, sub vertical direction of fluid flows, anomalously high layer pressure, and high level of anomalies of various geophysical fields are common for them. A certain class of fluid dynamic models describing consolidation of sedimentary basins, free oscillation processes slow and quick (at the final stage) fluid dynamic processes of the evolution of a sedimentary basin in subduction zones is considered for the first time. The last model of quick fluid dynamic processes reflects the process of formation of hydrocarbon deposits in the zones of collision of lithosphere plates. The results of numerical simulation and diagrams reflecting consecutive stages of the gas-fluid dynamic front propagation are assessed of the Pri-Caspian depression as the example. Calculations with this model will simultaneously be carried out for the sedimentary basins of Timan-Pechora region, Barents Sea, Volga-Ural area, etc. Hydrologic model of deep porous media and the idea of self-oscillation processes in fractured layers of the crust at different depths were used as the basis for developed concept. The content of these notions resides in the fact that there are conditions of dynamic balance in fractured layers originating as a result of combination and alternate actions of compaction and dilatance mechanisms. These mechanisms can be manifested in different combinations and under different conditions as well as can be complemented by other processes influencing on regime of fluid migration. They can act under condition of passive margin, rift and subduction zones as well as in consolidated platform and sheet. Self-oscillation regime, sub vertical direction of fluid flows, anomalously high layer pressure, and high level of anomalies of various geophysical fields are common for them. Specific manifestations of these mechanisms can vary in dependence on geological settings and geodynamic situations. In particular, periods of self-oscillations and depths of fractured layers can be various. Orientation of layers can be not only horizontal, but vertical as well, that is, self-oscillations can occur not only in deep porous media, but in faults and impaired fractured zones as well. Predominating vertical fluid migration can be accompanied by horizontal migration along crust waveguide. A set of fluid dynamic models is considered. Mathematical modeling of geodynamic and fluid dynamic processes in these zones seems very promising. Combined consideration of geodynamic and fluid dynamic aspects in a model of lithosphere plates collision enables to understand the influence of P-T conditions and shear deformations on the mechanism of hydrocarbon generation and to look after their migration and to explain these processes, but also to predict some features essential for the search and exploration of hydrocarbon fields in these regions and their classification. In terms of compaction models, multiphase filtration in a piezo-conduction mode and models of deep porous media major stages of fluid evolution under the conditions of developing passive margins and in the zones of collision of plates are described. In particular, compaction models of one of the stages of fluid mode evolution within a sedimentary basin and fluid migration from the convergence zones toward the upper layers are considered. In the final part of work, computation of fluid transfer of hydrocarbons in a pulse mode described by the equation of piezo-conductivity is presented for a mature oil-bearing sedimentary basin over individual sections for short periods of a few hundreds of years. These calculations were executed on the basis of a new mathematical method TEKON and computer programs for quantitative analysis of fluid migration and formation of hydrocarbon deposits with account taken for actual geometrical and lithological properties of the layers. On the basis of the specified numerical calculations the scales, form, and routes of fluid movement were disclosed, as well as the formation of zones of anomalously high rock pressure and non-traditional hydrocarbon deposits.

The relation between isotopic composition of argon and carbon in natural gases

NASA Technical Reports Server (NTRS)

Gavrilov, Y. Y.; Zhurov, Y. A.; Teplinskiy, G. I.

1977-01-01

The methods and results of determination of the argon and carbon isotope compositions of hydrocarbon gases of Mezozoic complexes of Western Siberia are presented. Based on the Ar-36, Ar-40, C-12, C-13 content of the various deposits and on the presumed mechanisms of entry of these isotopes into the deposits, it is concluded that formation of natural gas in some deposits included vertical migration from a lower complex.

Diel Variation in Beaked Whale Diving Behavior

DTIC Science & Technology

2008-01-01

While our results are only from a single study area and our sample size is small, diving patterns of these two species appear very stereotypic ...sharks of the genus Isistius (McSweeney et al. 2007). Cookie-cutter sharks are thought to exhibit diel vertical migrations, spending time near the...Mar. Mamm. Sci. 23: 666-687. 17 Mead, J.G. 1989. Beaked whales of the genus Mesoplodon. Pages 349-430 In S.H. Ridgway and R. Harrison

Large-Scale Crustal-Block-Extrusion During Late Alpine Collision.

PubMed

Herwegh, Marco; Berger, Alfons; Baumberger, Roland; Wehrens, Philip; Kissling, Edi

2017-03-24

The crustal-scale geometry of the European Alps has been explained by a classical subduction-scenario comprising thrust-and-fold-related compressional wedge tectonics and isostatic rebound. However, massive blocks of crystalline basement (External Crystalline Massifs) vertically disrupt the upper-crustal wedge. In the case of the Aar massif, top basement vertically rises for >12 km and peak metamorphic temperatures increase along an orogen-perpendicular direction from 250 °C-450 °C over horizontal distances of only <15 km (Innertkirchen-Grimselpass), suggesting exhumation of midcrustal rocks with increasing uplift component along steep vertical shear zones. Here we demonstrate that delamination of European lower crust during lithosphere mantle rollback migrates northward in time. Simultaneously, the Aar massif as giant upper crustal block extrudes by buoyancy forces, while substantial volumes of lower crust accumulate underneath. Buoyancy-driven deformation generates dense networks of steep reverse faults as major structures interconnected by secondary branches with normal fault component, dissecting the entire crust up to the surface. Owing to rollback fading, the component of vertical motion reduces and is replaced by a late stage of orogenic compression as manifest by north-directed thrusting. Buoyancy-driven vertical tectonics and modest late shortening, combined with surface erosion, result in typical topographic and metamorphic gradients, which might represent general indicators for final stages of continent-continent collisions.

Rural-urban migration including formal and informal workers in the urban sector: an agent-based numerical simulation study

NASA Astrophysics Data System (ADS)

Branco, Nilton; Oliveira, Tharnier; Silveira, Jaylson

2012-02-01

The goal of this work is to study rural-urban migration in the early stages of industrialization. We use an agent-based model and take into account the existence of informal and formal workers on the urban sector and possible migration movements, dependent on the agents' social and private utilities. Our agents are place on vertices of a square lattice, such that each vertex has only one agent. Rural, urban informal and urban formal workers are represented by different states of a three-state Ising model. At every step, a fraction a of the agents may change sectors or migrate. The total utility of a given agent is then calculated and compared to a random utility, in order to check if this agent turns into an actual migrant or changes sector. The dynamics is carried out until an equilibrium state is reached and equilibrium variables are then calculated and compared to available data. We find that a generalized Harris-Todaro condition is satisfied [1] on these equilibrium regimes, i.e, the ratio between expected wages between any pair of sectors reach a constant value. [4pt] [1] J. J. Silveira, A. L. Esp'indola and T. J. Penna, Physica A, 364, 445 (2006).

Benchmarking of vertically-integrated CO2 flow simulations at the Sleipner Field, North Sea

NASA Astrophysics Data System (ADS)

Cowton, L. R.; Neufeld, J. A.; White, N. J.; Bickle, M. J.; Williams, G. A.; White, J. C.; Chadwick, R. A.

2018-06-01

Numerical modeling plays an essential role in both identifying and assessing sub-surface reservoirs that might be suitable for future carbon capture and storage projects. Accuracy of flow simulations is tested by benchmarking against historic observations from on-going CO2 injection sites. At the Sleipner project located in the North Sea, a suite of time-lapse seismic reflection surveys enables the three-dimensional distribution of CO2 at the top of the reservoir to be determined as a function of time. Previous attempts have used Darcy flow simulators to model CO2 migration throughout this layer, given the volume of injection with time and the location of the injection point. Due primarily to computational limitations preventing adequate exploration of model parameter space, these simulations usually fail to match the observed distribution of CO2 as a function of space and time. To circumvent these limitations, we develop a vertically-integrated fluid flow simulator that is based upon the theory of topographically controlled, porous gravity currents. This computationally efficient scheme can be used to invert for the spatial distribution of reservoir permeability required to minimize differences between the observed and calculated CO2 distributions. When a uniform reservoir permeability is assumed, inverse modeling is unable to adequately match the migration of CO2 at the top of the reservoir. If, however, the width and permeability of a mapped channel deposit are allowed to independently vary, a satisfactory match between the observed and calculated CO2 distributions is obtained. Finally, the ability of this algorithm to forecast the flow of CO2 at the top of the reservoir is assessed. By dividing the complete set of seismic reflection surveys into training and validation subsets, we find that the spatial pattern of permeability required to match the training subset can successfully predict CO2 migration for the validation subset. This ability suggests that it might be feasible to forecast migration patterns into the future with a degree of confidence. Nevertheless, our analysis highlights the difficulty in estimating reservoir parameters away from the region swept by CO2 without additional observational constraints.

Metabolic physiology of the Humboldt squid, Dosidicus gigas: Implications for vertical migration in a pronounced oxygen minimum zone

NASA Astrophysics Data System (ADS)

Rosa, Rui; Seibel, Brad A.

2010-07-01

The Humboldt (or jumbo) squid, Dosidicus gigas, is an active predator endemic to the Eastern Pacific that undergoes diel vertical migrations into a pronounced oxygen minimum layer (OML). Here, we investigate the physiological mechanisms that facilitate these migrations and assess the associated costs and benefits. Exposure to hypoxic conditions equivalent to those found in the OML (∼10 μM O 2 at 10 °C) led to a significant reduction in the squid’s routine metabolic rate (RMR), from 8.9 to 1.6 μmol O 2 g -1 h -1 ( p < 0.05), and a concomitant increase in mantle muscle octopine levels (from 0.50 to 5.24 μmol g -1 tissue, p < 0.05). Enhanced glycolitic ATP production accounted for only 7.0% and 2.8% at 10 °C and 20 °C, respectively, of the energy deficit that resulted from the decline in aerobic respiration. The observed metabolic suppression presumably extends survival time in the OML by conserving the finite stores of fermentable substrate and avoiding the accumulation of the deleterious anaerobic end products in the tissues. RMR increased significantly with temperature ( p < 0.05), from 8.9 (at 10 °C) to 49.85 μmol O 2 g -1 h -1 (at 25 °C) which yielded a Q10 of 2.0 between 10 and 20 °C and 7.9 between 20 and 25 °C ( p < 0.05). These results suggest that 25 °C, although within the normal surface temperature range in the Gulf of California, is outside this species’ normal temperature range. By following the scattering layer into oxygen-enriched shallow water at night, D. gigas may repay any oxygen debt accumulated during the daytime. The dive to deeper water may minimize exposure to stressful surface temperatures when most prey have migrated to depth during the daytime. The physiological and ecological strategies demonstrated here may have facilitated the recent range expansion of this species into northern waters where expanding hypoxic zones prohibit competing top predators.

Vestibular Migraine in Children and Adolescents: Clinical Findings and Laboratory Tests

PubMed Central

Langhagen, Thyra; Lehrer, Nicole; Borggraefe, Ingo; Heinen, Florian; Jahn, Klaus

2015-01-01

Introduction: Vestibular migraine (VM) is the most common cause of episodic vertigo in children. We summarize the clinical findings and laboratory test results in a cohort of children and adolescents with VM. We discuss the limitations of current classification criteria for dizzy children. Methods: A retrospective chart analysis was performed on 118 children with migraine related vertigo at a tertiary care center. Patients were grouped in the following categories: (1) definite vestibular migraine (dVM); (2) probable vestibular migraine (pVM); (3) suspected vestibular migraine (sVM); (4) benign paroxysmal vertigo (BPV); and (5) migraine with/without aura (oM) plus vertigo/dizziness according to the International Classification of Headache Disorders, 3rd edition (beta version). Results: The mean age of all patients was 12 ± 3 years (range 3–18 years, 70 females). 36 patients (30%) fulfilled criteria for dVM, 33 (28%) for pVM, 34 (29%) for sVM, 7 (6%) for BPV, and 8 (7%) for oM. Somatoform vertigo (SV) co-occurred in 27% of patients. Episodic syndromes were reported in 8%; the family history of migraine was positive in 65%. Mild central ocular motor signs were found in 24% (most frequently horizontal saccadic pursuit). Laboratory tests showed that about 20% had pathological function of the horizontal vestibulo-ocular reflex, and almost 50% had abnormal postural sway patterns. Conclusion: Patients with definite, probable, and suspected VM do not differ in the frequency of ocular motor, vestibular, or postural abnormalities. VM is the best explanation for their symptoms. It is essential to establish diagnostic criteria in clinical studies. In clinical practice, however, the most reasonable diagnosis should be made in order to begin treatment. Such a procedure also minimizes the fear of the parents and children, reduces the need to interrupt leisure time and school activities, and prevents the development of SV. PMID:25674076

Lunar cycles in diel prey migrations exert a stronger effect on the diving of juveniles than adult Galápagos fur seals.

PubMed Central

Horning, M; Trillmich, F

1999-01-01

In our study of the development of diving in Galápagos fur seals, we analysed changes in diving activity and body mass trends over the lunar cycle. Based on previously observed lunar cycles in colony attendance patterns, we hypothesized a greater impact of prey migrations of deep scattering layer organisms on younger fur seals. Using electronic dive recorders, we determined that seals dived less and deeper on moonlit nights than at new moon, and incurred body mass losses. These changes in foraging over the lunar cycle correlate with the suppression of the vertical migration of prey by lunar light. All effects were more pronounced in juveniles than adult females, with greater relative mass loss during full moon, which must (i) negatively affect long-term juvenile growth rates, (ii) lengthen periods of maternal dependence, and (iii) contribute to the lowest reproductive rate reported for seals. This underlines the importance of studying ontogeny in order to understand life histories, and for determining the susceptibility of animal populations to fluctuations in food availability. PMID:10406130

Zooplankton and the oceanography of the eastern tropical Pacific: A review

NASA Astrophysics Data System (ADS)

Fernández-Álamo, María Ana; Färber-Lorda, Jaime

2006-05-01

We review the spatial and temporal patterns of zooplankton in the eastern tropical Pacific Ocean and relationships with oceanographic factors that affect zooplankton distribution, abundance and trophic relationships. Large-scale spatial patterns of some zooplankton groups show broad coincidence with surface water masses, circulation, and upwelling regions, in agreement with an ecological and dynamic partitioning of the pelagic ecosystem. The papers reviewed and a new compilation of zooplankton volume data at large-scale show that abundance patterns of zooplankton biomass have their highest values in the upwelling regions, including the Gulf of Tehuantepec, the Costa Rica Dome, the equatorial cold tongue, and the coast of Peru. Some of the first studies of zooplankton vertical distribution were done in this region, and a general review of the topic is presented. The possible physiological implications of vertical migration in zooplankton and the main hypotheses are described, with remarks on the importance of the oxygen minimum zone (OMZ) as a barrier to both the vertical distribution and migration of zooplankton in the region. Recent results, using multiple-net gear, show that vertical distribution is more complex than previously thought. There are some well-adapted species that do live and migrate within the OMZ. Temporal patterns are reviewed and summarized with historical data. Seasonal variations in zooplankton biomass follow productivity cycles in upwelling areas. No zooplankton time series exist to resolve ENSO effects in oceanic regions, but some El Niño events have had effects in the Peru Current ecosystem. Multidecadal periods of up to 50 years show a shift from a warm sardine regime with a low zooplankton biomass to a cool anchovy regime in the eastern Pacific with higher zooplankton biomasses. However, zooplankton volume off Peru has remained at low values since the 1972 El Niño, a trend opposite to that of anchoveta biomass since 1984. Studies of trophic relations emphasize the difference in the productivity cycle in the eastern tropical Pacific compared to temperate or polar ecosystems, with no particular peaks in the stocks of either zooplankton or phytoplankton. Productivity is more dependent on local events like coastal upwelling or water circulation, especially in the equatorial countercurrent and around the equatorial cool-tongue. Micrograzers are very important in the tropics as are predatory mesozooplankton. Up to 70% of the daily primary productivity is consumed by microzooplankton, which thus regulates the phytoplankton stocks. Micrograzers are an important link between primary producers, including bacteria, and mesozooplankton, constituting up to 80% of mesozooplankton food. Oceanography affects zooplankton trophic relationships through spatial-temporal effects on primary productivity and on the distributions of metabolic factors, food organisms, and predators. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific.

The biological pump: Profiles of plankton production and consumption in the upper ocean

NASA Astrophysics Data System (ADS)

Longhurst, Alan R.; Glen Harrison, W.

The ‘biological pump’ mediates flux of carbon to the interior of the ocean by interctions between the components of the vertically-structured pelagic ecosystem of the photic zone. Chlorophyll profiles are not a simple indicator of autotrophic biomass or production, because of non-linearities in the physiology of cells and preferential vertical distribution of taxa. Profiles of numbers or biomass of heterotrophs do not correspond with profiles of consumption, because of depth-selection (taxa, seasons) for reasons unconnected with feeding. Depths of highest plant biomass, chlorophyll and growth rate coincide when these depths are shallow, but become progressively separated in profiles where they are deeper - so that highest growth rate lies progressively shallower than the chloropyll maximum. It is still uncertain how plant biomass is distributed in deep profiles. Depths of greatest heterotroph biomass (mesozooplankton) are usually close to depths of fastest plant growth rate, and thus lie shallower than the chlorophyll maximum in profiles where this itself is deep. This correlation is functional, and relates to the role of heterotrophs in excreting metabolic wastes (especially ammonia), which may fuel a significant component of integrated algal production, especially in the oligotrophic ocean. Some, but not all faecal material from mesozooplankton of the photic zone appears in vertical flux below the pycnocine, depending on the size of the source organisms, and the degree of vertical mixing above the pycnocline. Diel, but probably not seasonal, vertical migration is significant in the vertical flux of dissolved nitrogen. Regional generalisations of the vertical relations of the main components of the ‘biological pump’ now appear within reach, and an approach is suggested.

Short-Term Fidelity, Habitat Use and Vertical Movement Behavior of the Black Rockfish Sebastes schlegelii as Determined by Acoustic Telemetry

PubMed Central

Zhang, Yingqiu; Xu, Qiang; Alós, Josep; Liu, Hui; Xu, Qinzeng; Yang, Hongsheng

2015-01-01

The recent miniaturization of acoustic tracking devices has allowed fishery managers and scientists to collect spatial and temporal data for sustainable fishery management. The spatial and temporal dimensions of fish behavior (movement and/or vertical migrations) are particularly relevant for rockfishes (Sebastes spp.) because most rockfish species are long-lived and have high site fidelity, increasing their vulnerability to overexploitation. In this study, we describe the short-term (with a tracking period of up to 46 d) spatial behavior, as determined by acoustic tracking, of the black rockfish Sebastes schlegelii, a species subject to overexploitation in the Yellow Sea of China. The average residence index (the ratio of detected days to the total period from release to the last detection) in the study area was 0.92 ± 0.13, and most of the tagged fish were detected by only one region of the acoustic receiver array, suggesting relatively high site fidelity to the study area. Acoustic tracking also suggested that this species is more frequently detected during the day than at night in our study area. However, the diel detection periodicity (24 h) was only evident for certain periods of the tracking time, as revealed by a continuous wavelet transform. The habitat selection index of tagged S. schlegelii suggested that S. schlegelii preferred natural reefs, mixed sand/artificial reef bottoms and mixed bottoms of boulder, cobble, gravel and artificial reefs. The preference of this species for the artificial reefs that were recently deployed in the study area suggests that artificial seascapes may be effective management tools to attract individuals. The vertical movement of tagged S. schlegelii was mostly characterized by bottom dwelling behavior, and there was high individual variability in the vertical migration pattern. Our results have important implications for S. schlegelii catchability, the implementation of marine protected areas, and the identification of key species habitats, and our study provides novel information for future studies on the sustainability of this important marine resource in eastern China. PMID:26322604

Natural radionuclides in rocks and soils of the high-mountain regions of the Great Caucasus

NASA Astrophysics Data System (ADS)

Asvarova, T. A.; Abdulaeva, A. S.; Magomedov, M. A.

2012-06-01

The results of the radioecological survey in the high-mountain regions of the Great Caucasus at the heights from 2200 to 3800 m a.s.l. are considered. This survey encompassed the territories of Dagestan, Azerbaijan, Georgia, Chechnya, Northern Ossetia-Alania, Kabardino-Balkaria, Karachay-Cherkessia, and the Stavropol and Krasnodar regions. The natural γ background radiation in the studied regions is subjected to considerable fluctuations and varies from 6 to 40 μR/h. The major regularities of the migration of natural radionuclides 238U, 232Th, 226Ra, and 40K in soils in dependence on the particular environmental conditions (the initial concentration of the radionuclides in the parent material; the intensity of pedogenesis; the intensity of the vertical and horizontal migration; and the geographic, climatic, and landscape-geochemical factors) are discussed.

Continuing Investigations of the Relationship Between Fin Whales, Zooplankton Concentrations and Hydrothermal Venting on the Juan De Fuca Ridge

DTIC Science & Technology

2013-09-30

Fuca Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean...layer of increased acoustic backscatter near the 3 top of the hydrothermal plume (Thomson et al., 1991; Burd et al., 1992), leading to the...shallow species, which presumably migrate vertically between the upper ocean and the hydrothermal plume (Burd and Thomson, 1994, 1995). Our approach

Planar Laser Imaging of Scattering and Fluorescence of Zooplankton Feeding in Layers of Phytoplankton in situ

DTIC Science & Technology

2010-09-30

planktonic ecosystems. OBJECTIVES Our objectives in this work are to 1) visualize and quantify herbivorous copepod feeding in the laboratory...and 2) to apply these methods in the field to observe the dynamics of copepod feeding in situ. In particular we intend to test the “feeding sorties...hypothesis vs. the “in situ feeding” hypothesis regarding the location and timing of copepod feeding and vertical migration. APPROACH Previous

On the exposure history of the lunar regolith. [to cosmic rays

NASA Technical Reports Server (NTRS)

Gold, T.; Williams, G. J.

1974-01-01

The observed minimum and mean values of track densities in lunar grains are both found to exceed the values expected from exposure with redistribution by vertical mixing, and the percentage of the smaller grains showing very high track densities is too large by a factor of more than ten. Previous exposure of the material (in space before accretion onto the moon or in regions from which net migration has occurred) may be necessitated.

Generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis

PubMed Central

Giometto, Andrea; Altermatt, Florian; Maritan, Amos; Stocker, Roman; Rinaldo, Andrea

2015-01-01

Phototaxis, the process through which motile organisms direct their swimming toward or away from light, is implicated in key ecological phenomena (including algal blooms and diel vertical migration) that shape the distribution, diversity, and productivity of phytoplankton and thus energy transfer to higher trophic levels in aquatic ecosystems. Phototaxis also finds important applications in biofuel reactors and microbiopropellers and is argued to serve as a benchmark for the study of biological invasions in heterogeneous environments owing to the ease of generating stochastic light fields. Despite its ecological and technological relevance, an experimentally tested, general theoretical model of phototaxis seems unavailable to date. Here, we present accurate measurements of the behavior of the alga Euglena gracilis when exposed to controlled light fields. Analysis of E. gracilis’ phototactic accumulation dynamics over a broad range of light intensities proves that the classic Keller–Segel mathematical framework for taxis provides an accurate description of both positive and negative phototaxis only when phototactic sensitivity is modeled by a generalized “receptor law,” a specific nonlinear response function to light intensity that drives algae toward beneficial light conditions and away from harmful ones. The proposed phototactic model captures the temporal dynamics of both cells’ accumulation toward light sources and their dispersion upon light cessation. The model could thus be of use in integrating models of vertical phytoplankton migrations in marine and freshwater ecosystems, and in the design of bioreactors. PMID:25964338

Laboratory Experiments on Meandering Meltwater Channels

NASA Astrophysics Data System (ADS)

Fernandez, R.; Berens, J.; Parker, G.; Stark, C. P.

2017-12-01

Meandering channels of all scales and flowing over a wide variety of media have common planform patterns. Although the analogy in planform suggests there is a common underlying framework, the constitutive relations driving planform evolution through vertical incision/deposition and lateral migration differ from medium to medium. The driving processes in alluvial and mixed bedrock-alluvial meandering channels have been studied substantially over the last decades. However, this is not the case for meandering channels in other media such as ice or soluble rock. Here we present results from experiments conducted at the Ven Te Chow Hydrosystems Laboratory of the University of Illinois at Urbana-Champaign on meltwater meandering channels. A rivulet is carved into an ice block and water is allowed to flow at a constant discharge. Planform evolution is analyzed with time lapse imaging and complemented with rubber molds of the channel once the experiment is over. These molds give us the full 3D structure of the meandering, including incisional overhang. Vertical incision rates are measured throughout the run by taking elevations along the channel, and these measurements are complemented with analysis from the molds. We show examples of meandering of intense amplitude with deep overhangs. Features resembling scroll bars document cyclically punctuated melting. We report on lateral migration rates, incision rates, sinuosity, channel depths, channel widths, reach averaged velocities, bend wavelengths and amplitudes and compare them to values reported in the literature for alluvial rivers.

From immobilized cells to motile cells on a bed-of-nails: effects of vertical nanowire array density on cell behaviour

PubMed Central

Persson, Henrik; Li, Zhen; Tegenfeldt, Jonas O.; Oredsson, Stina; Prinz, Christelle N.

2015-01-01

The field of vertical nanowire array-based applications in cell biology is growing rapidly and an increasing number of applications are being explored. These applications almost invariably rely on the physical properties of the nanowire arrays, creating a need for a better understanding of how their physical properties affect cell behaviour. Here, we investigate the effects of nanowire density on cell migration, division and morphology for murine fibroblasts. Our results show that few nanowires are sufficient to immobilize cells, while a high nanowire spatial density enables a ”bed-of-nails” regime, where cells reside on top of the nanowires and are fully motile. The presence of nanowires decreases the cell proliferation rate, even in the “bed-of-nails” regime. We show that the cell morphology strongly depends on the nanowire density. Cells cultured on low (0.1 μm−2) and medium (1 μm−2) density substrates exhibit an increased number of multi-nucleated cells and micronuclei. These were not observed in cells cultured on high nanowire density substrates (4 μm−2). The results offer important guidelines to minimize cell-function perturbations on nanowire arrays. Moreover, these findings offer the possibility to tune cell proliferation and migration independently by adjusting the nanowire density, which may have applications in drug testing. PMID:26691936

Generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis.

PubMed

Giometto, Andrea; Altermatt, Florian; Maritan, Amos; Stocker, Roman; Rinaldo, Andrea

2015-06-02

Phototaxis, the process through which motile organisms direct their swimming toward or away from light, is implicated in key ecological phenomena (including algal blooms and diel vertical migration) that shape the distribution, diversity, and productivity of phytoplankton and thus energy transfer to higher trophic levels in aquatic ecosystems. Phototaxis also finds important applications in biofuel reactors and microbiopropellers and is argued to serve as a benchmark for the study of biological invasions in heterogeneous environments owing to the ease of generating stochastic light fields. Despite its ecological and technological relevance, an experimentally tested, general theoretical model of phototaxis seems unavailable to date. Here, we present accurate measurements of the behavior of the alga Euglena gracilis when exposed to controlled light fields. Analysis of E. gracilis' phototactic accumulation dynamics over a broad range of light intensities proves that the classic Keller-Segel mathematical framework for taxis provides an accurate description of both positive and negative phototaxis only when phototactic sensitivity is modeled by a generalized "receptor law," a specific nonlinear response function to light intensity that drives algae toward beneficial light conditions and away from harmful ones. The proposed phototactic model captures the temporal dynamics of both cells' accumulation toward light sources and their dispersion upon light cessation. The model could thus be of use in integrating models of vertical phytoplankton migrations in marine and freshwater ecosystems, and in the design of bioreactors.

Dual-vergence structure from multiple migration of widely spaced OBSs

NASA Astrophysics Data System (ADS)

Yelisetti, Subbarao; Spence, George D.; Scherwath, Martin; Riedel, Michael; Klaeschen, Dirk

2017-10-01

The detailed structure of the northern Cascadia basin and frontal ridge region was obtained using data from several widely spaced ocean bottom seismometers (OBSs). Mirror imaging was used in which the downgoing multiples (mirror signal) are migrated as they provide information about a much larger area than imaging with primary signal alone. Specifically, Kirchhoff time migration was applied to hydrophone and vertical geophone data. Our results indicate remarkable structures that were not observed on the northern Cascadia margin in previous single-channel or multi-channel seismic (MCS) data. Results show that, in these water depths (2.0-2.5 km), an OBS can image up to 5 km on either side of its position on the seafloor and hence an OBS spacing of 5 km is sufficient to provide a two-fold migration stack. Results also show the top of the igneous oceanic crust at 5-6 km beneath the seafloor using only a small airgun source (120 in.3). Specifically, OBS migration results clearly show the continuity of reflectors which enabled the identification of frontal thrusts and a main thrust fault. These faults indicate, for the first time on this margin, the presence of a dual-vergence structure. These kinds of structures have so far been observed in < 0.5% of modern convergent margins and could be related to horizontal compression associated with subduction and low basal shear stress resulting from over-pressure. Reanalysis of previous MCS data from this region augmented the OBS migration results and further suggests that the vergence switches from seaward to landward around central Vancouver Island. Furthermore, fault geometry analyses indicate that the total amount of shortening accommodated due to faulting and folding is about 3 km, which suggest that thrusting would have started at least ∼ 65 ky ago.

Petroleum generation and migration in the Mesopotamian Basin and Zagros fold belt of Iraq: Results from a basin-modeling study

USGS Publications Warehouse

Pitman, Janet K.; Steinshouer, D.; Lewan, M.D.

2004-01-01

A regional 3-D total petroleum-system model was developed to evaluate petroleum generation and migration histories in the Mesopotamian Basin and Zagros fold belt in Iraq. The modeling was undertaken in conjunction with Middle East petroleum assessment studies conducted by the USGS. Regional structure maps, isopach and facies maps, and thermal maturity data were used as input to the model. The oil-generation potential of Jurassic source-rocks, the principal known source of the petroleum in Jurassic, Cretaceous, and Tertiary reservoirs in these regions, was modeled using hydrous pyrolysis (Type II-S) kerogen kinetics. Results showed that oil generation in source rocks commenced in the Late Cretaceous in intrashelf basins, peak expulsion took place in the late Miocene and Pliocene when these depocenters had expanded along the Zagros foredeep trend, and generation ended in the Holocene when deposition in the foredeep ceased. The model indicates that, at present, the majority of Jurassic source rocks in Iraq have reached or exceeded peak oil generation and most rocks have completed oil generation and expulsion. Flow-path simulations demonstrate that virtually all oil and gas fields in the Mesopotamian Basin and Zagros fold belt overlie mature Jurassic source rocks (vertical migration dominated) and are situated on, or close to, modeled migration pathways. Fields closest to modeled pathways associated with source rocks in local intrashelf basins were charged earliest from Late Cretaceous through the middle Miocene, and other fields filled later when compression-related traps were being formed. Model results confirm petroleum migration along major, northwest-trending folds and faults, and oil migration loss at the surface.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

NASA Astrophysics Data System (ADS)

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g-1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g-1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g-1) and high energy density (98.1 Wh kg-1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes.

PubMed

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-08

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g -1 , which is 6 times higher than disordered CNTs in HClO 4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g -1 ), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g -1 ) and high energy density (98.1 Wh kg -1 ) in EMIBF 4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

PubMed Central

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-01-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g−1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g−1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g−1) and high energy density (98.1 Wh kg−1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation. PMID:28272474

Study of Flapping Flight Using Discrete Vortex Method Based Simulations

NASA Astrophysics Data System (ADS)

Devranjan, S.; Jalikop, Shreyas V.; Sreenivas, K. R.

2013-12-01

In recent times, research in the area of flapping flight has attracted renewed interest with an endeavor to use this mechanism in Micro Air vehicles (MAVs). For a sustained and high-endurance flight, having larger payload carrying capacity we need to identify a simple and efficient flapping-kinematics. In this paper, we have used flow visualizations and Discrete Vortex Method (DVM) based simulations for the study of flapping flight. Our results highlight that simple flapping kinematics with down-stroke period (tD) shorter than the upstroke period (tU) would produce a sustained lift. We have identified optimal asymmetry ratio (Ar = tD/tU), for which flapping-wings will produce maximum lift and find that introducing optimal wing flexibility will further enhances the lift.

Preferred negative geotactic orientation in mobile cells: Tetrahymena results.

PubMed Central

Noever, D A; Cronise, R; Matsos, H C

1994-01-01

For the protozoan species Tetrahymena a series of airplane experiments are reported, which varied gravity as an active laboratory parameter and tested for corresponding changes in geotaxic orientation of single cells. The airplane achieved alternating periods of low (0.01 g) and high (1.8 g; g = 980 cm/s) gravity by flying repeated Keplerian parabolas. The experimental design was undertaken to clearly distinguish gravity from competing aerodynamic and chemical gradients. In this way, each culture served as its own control, with gravity level alone determining the orientational changes. On average, 6.3% of the Tetrahymena oriented vertically in low gravity, while 27% oriented vertically in high-gravity phases. Simplified physical models are explored for describing these cell trajectories as a function of gravity, aerodynamic drag, and lift. The notable effect of gravity on turning behavior is emphasized as the biophysical cause of the observed negative geotaxis in Tetrahymena. A fundamental investigation of the biological gravity receptor (if it exists) and improved modeling for vertical migration in important types of ocean plankton motivate the present research. Images FIGURE 1 PMID:7858146

Preferred Negative Geotactic Orientation in Mobile Cells: Tetrahymena Results

NASA Technical Reports Server (NTRS)

Noever, David A.; Cronise, Raymond; Matsos, Helen C.

1994-01-01

For the protozoan species Tetrahymena a series of airplane experiments are reported, which varied gravity as an active laboratory parameter and tested for corresponding changes in geotaxic orientation of single cells. The airplane achieved altemating periods of low (0.01 g) and high (1.8 g, g = 980 cm/s) gravity by flying repeated Keplerian parabolas. The experimental design was undertaken to clearly distinguish gravity from competing aerodynamic and chemical gradients. In this way, each culture served as its own control, with gravity level alone determining the orientational changes. On average, 6.3% of the Tetrahymena oriented vertically in low gravity, while 27% oriented vertically in high-gravity phases. Simplified physical models are explored for describing these cell trajectores as a function of gravity, aerodynamic drag, and lift. The notable effect of gravity on turning behavior is emphasized as the biophysical cause of the observed negative geotaxis in Tetrahymena. A fundamental investigation of the biological gravity receptor (it it exists) and improved modeling for vertical migration in important types of ocean plankton motivate the present research.

Transform migration and vertical tectonics at the Romanche fracture zone, equatorial Atlantic

NASA Astrophysics Data System (ADS)

Bonatti, E.; Ligi, M.; Gasperini, L.; Peyve, A.; Raznitsin, Y.; Chen, Y. J.

1994-11-01

The Romanche transform offsets the Mid-Atlantic Ridge (MAR) axis by about 950 km in the equatorial Atlantic. Multibeam and high-resolution multichannel seismic reflection surveys as well as rock sampling were carried out on the eastern part of the transform with the R/V Akademik Strakhov as part of the Russian-Italian Mid-Atlantic Ridge Project (PRIMAR). Morphobathymetric data show the existence on the northern side of the transform of a major 800-km-long aseismic valley oriented 10 deg to 15 deg from the active valley; it disappears about 150 km from the western MAR segment. The aseismic valley marks probably the former location of the Romanche transform ('PaleoRomanche') that was active up to roughly 8-10 Ma, when the transform boundary migrated to its present position. A temporary microplate developed during the migration and reorientation of the transform. This microplate changed its sense of motion as it was transferred from the South American to the African plate. Evaluation of the seismic reflection data as well as study of samples of carbonates, ventifact basaltic pebbles and gabbroic, peridotitic and basaltic rocks recovered at different sites on the transverse ridge, suggest that (1) the summit of the transverse ridge was above sea level at and before about 5 Ma; (2) the transverse ridge subsided since then at an average rate 1 order of magnitude faster than the predicted thermal contraction rate; its summit was flattened by erosion at sea level during subsidence; (3) the transverse ridge is an uplifted sliver of lithosphere and not a volcanic constructional feature; and (4) transtensional and transpressional tectonics have affected the transverse ridge. Uplift may have been caused primarily by thrust faulting induced by transpression related to the oblique impact of the lithospheric plate against the former (PaleoRomanche) and the younger transform boundaries, before and during the transition to the present boundary. After migration of the transform boundary to its present position, transpression was replaced by transtension and by subsidence of the transverse ridge. An aseismic axial rift valley impacting against the transform valley about 80 km west of the present RTI suggests eastward ridge jumping and probably followed transform migration. Localized transtension or transpression due to bends in the orientation of the transform may have caused intense although localized vertical movements, such as those that formed an ultradeep (greater than 7800 m) pull-apart basin along the transform valley.

Radially Magnetized Protoplanetary Disk: Vertical Profile

NASA Astrophysics Data System (ADS)

Russo, Matthew; Thompson, Christopher

2015-11-01

This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field Br ˜ (10-4-10-2)(r/ AU)-2 G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ˜1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10-8 M⊙ yr-1 are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper.

Preliminary Paleomagnetically Determined Vertical-Axis Rotations and their Relationship to Extensional Events of the Southern Walker Lane

NASA Astrophysics Data System (ADS)

Johnson, S.; Geissman, J. W.; Katopody, D. T.; Kerstetter, S. R.; Oldow, J. S.

2016-12-01

The northern part of the southern Walker Lane experienced three extensional events from the late Oligocene to the Holocene: 1) late Oligocene to early Miocene WNW and ENE trending half-grabens, 2) Late Miocene to early Pliocene high-magnitude extension on a low-angle normal fault, and 3) contemporary transtensional deformation that initiated at 4 Ma. Each of the extensional events controlled deposition of synextensional strata. What is less understood is the timing and magnitude of vertical axis rotation and its relationship to each of the three extensional events. As part of a recent and ongoing multidisciplinary study to better understand the complex nature and history of these extensional events we present preliminary paleomagnetic data from 55 sites in Miocene extrusive igneous rocks which record that clockwise vertical-axis rotation played a significant role in accommodating displacement in these systems. Recently refined stratigraphic, geochronologic, and structural controls have allowed the detailed paleomagnetic sampling required for this study. We seek to provide better constraints on timing, areal extent, and distribution of vertical axis rotation to answer how vertical axis rotation interacted with these extensional events. Consistent with past studies, we have recognized 20-30 degrees of clockwise vertical-axis rotation distributed heterogeneously throughout the study area. However, clockwise vertical-axis rotations are no longer occurring in this region as evidenced by modern geodetic velocity fields. The accommodation of displacement by vertical axis rotations in this region likely ceased by early Pliocene to late Miocene when the structural step-over migrated to the northwest to its present day manifestation in the Mina Deflection. Anisotropy of magnetic susceptibility (AMS), used as a proxy for flow direction in igneous extrusive rocks, provides evidence that at least one late Oligocene-early Miocene half-grabens acted as near-source depositional centers concurrent with extension.

Enhanced migration of polychlorodibenzo-p-dioxins and furans in the presence of pentachlorophenol-treated oil in soil around utility poles: screening model validation.

PubMed

Bulle, Cécile; Samson, Réjean; Deschênes, Louise

2010-03-01

Field samples were collected around six pentachlorophenol (PCP)-treated wooden poles (in clay, organic soil, and sand) to evaluate the vertical migration of polychlorodibenzo-p-dioxins and furans (PCDD/Fs). Soils were characterized, PCDD/Fs, C(10)-C(50), and PCP were analyzed for seven composite samples located at a depth from 0 to 100 cm and at a distance from 0 to 50 cm from each pole. Concentrations of PCDD/Fs measured in organic soils were the highest (maximum 1.2E + 05 pg toxic equivalent TEQ/g soil), followed by clay (maximum 3.8E + 04 pg TEQ/g soil) and sand (maximum 1.8E + 04 pg TEQ/g soil). Model predictions, including the influence of wood treatment oil, were validated using measured concentration values in soils around poles. The model predicts a migration of PCDD/Fs due to the migration of oil, which differs depending on the type of soil: in clay, 90% of PCDD/Fs are predicted to remain in the first 29 cm, whereas in sand, 80 to 90% of the emitted PCDD/Fs are predicted to migrate deeper than 185 cm. For the organic soil, the predicted migration depth varies from 90 to 155 cm. This screening model allows evaluating the danger of microcontaminated sites around PCP-treated wooden poles: from a risk assessment perspective, in the case of organic soil and clay, no PCDD/F contamination is to be expected below the pole, but high levels of PCDD/Fs can be found in the first 2 m below the surface. For sand, however, significantly lower levels of PCDD/Fs were predicted in the surface soil, while the migration depth remains elevated, posing an inherent danger of aquifer contamination under the pole.

Cadmium removal from urban stormwater runoff via bioretention technology and effluent risk assessment for discharge to surface water.

PubMed

Wang, Jianlong; Zhang, Pingping; Yang, Liqiong; Huang, Tao

2016-01-01

Bioretention technology, a low-impact development stormwater management measure, was evaluated for its ability to remove heavy metals (specifically cadmium, Cd) from urban stormwater runoff. Fine sand, zeolite, sand and quartz sand were selected as composite bioretention media. The effects of these materials on the removal efficiency, chemical forms, and accumulation and migration characteristics of Cd were examined in laboratory scale bioretention columns. Heretofore, few studies have examined the removal of Cd by bioretention. A five-step sequential extraction method, a single-contamination index method, and an empirical migration equation were used in the experiments. The average Cd removal efficiency of quartz sand approached 99%, and removal by the other media all exceeded 90%. The media types markedly affected the forms of Cd found in the columns as well as its vertical migration rate. The Cd accumulated in the four media was mainly in residual form; moreover, accumulation of Cd occurred mainly in the surface layer of the bioretention column. The migration depth of Cd in the four media increased with elapsed time, in the following sequence: zeolite>quartz sand>fine sand>sand. In contrast, the migration rate decreased with elapsed time, and the migration rate of Cd was lowest in sand (0.015 m per annum over the first ten years). The comprehensive risk index analysis indicated that the risk arising from Cd discharge to surface water was "intermediate", and that the degree of risk was lowest in sand, then quartz sand, zeolite, and fine sand in sequence. These results indicate that the adsorption and accumulation of Cd in the four media are more significant than the migration of Cd. In addition, the results of Cd risk assessment for the effluent indicate that each of the four media can serve as long-term adsorption material in a bioretention facility for purifying stormwater runoff. Copyright © 2016 Elsevier B.V. All rights reserved.

Surrogate Indicators of Radionuclide Migration at the Amargosa Desert Research Site, Nye County, Nevada

NASA Astrophysics Data System (ADS)

Stonestrom, D. A.; Andraski, B. J.; Baker, R. J.; Luo, W.; Michel, R. L.

2005-05-01

Contaminant-transport processes are being investigated at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS), adjacent to the Nation's first commercial disposal facility for low-level radioactive waste. Gases containing tritium and radiocarbon are migrating through a 110-m thick unsaturated zone from unlined trenches that received waste from 1962 to 1992. Information on plume dynamics comes from an array of shallow (<2 m) and two vertical arrays of deep (5-109 m) gas-sampling ports, plus ground-water monitoring wells. Migration is dominated by lateral transport in the upper 50 m of sediments. Radiological analyses require ex-situ wet-chemical techniques, because in-situ sensors for the radionuclides of interest do not exist. As at other LLRW-disposal facilities, radionuclides at the ADRS are mixed with varying amounts of volatile organic compounds (VOCs) and other substances. Halogenated-methanes, -ethanes, and -ethenes dominate the complex mixture of VOCs migrating from the disposal area. These compounds and their degradates provide a distinctive "fingerprint" of contamination originating from low-level radioactive waste. Carbon-dioxide and VOC anomalies provide indicator proxies for radionuclide contamination. Spatial and temporal patterns of co-disposed and byproduct constituents provide field-scale information about physical and biochemical processes involved in transport. Processes include reduction and biorespiration within trenches, and largely non-reactive, barometrically dispersed diffusion away from trenches.

Radioactive Contamination of Alluvial Soils in the Taiga Landscapes of Yakutia with 137Cs, 226Ra, and 238U

NASA Astrophysics Data System (ADS)

Chevychelov, A. P.; Sobakin, P. I.

2017-12-01

The concentrations and distribution of 137Cs in alluvial soils (Fluvisols) of the upper and middle reaches of the Markha River in the northwest of Yakutia and 226Ra and 238U in alluvial soils within the El'kon uranium ore deposit in the south of Yakutia have been studied. It is shown that the migration of radiocesium in the permafrost-affected soils of Yakutia owing to alluviation processes extends to more than 600 km from the source of the radioactive contamination. The migration of 137Cs with water flows is accompanied by its deposition in the buried horizons of alluvial soils during extremely high floods caused by ice jams. In the technogenic landscapes of southern Yakutia, active water migration of 238U and 226Ra from radioactive dump rocks. The leaching of 238U with surface waters from the rocks is more intense than the leaching of 226Ra. The vertical distribution patterns of 238U and 226Ra in the profiles of alluvial soils are complex. Uranium tends to accumulate in the surface humus horizon and in the buried soil horizons, whereas radium does not display any definite regularities of its distribution in the soil profiles. At present, the migration of 238U and 226Ra with river water and their accumulation in the alluvial soils extend to about 30 km from the source.

Investigating the Relationship Between Fin and Blue Whale Locations, Zooplankton Concentrations and Hydrothermal Venting on the Juan de Fuca Ridge

DTIC Science & Technology

2008-01-01

such correlations in terms of the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean. OBJECTIVES We are...in a 100-m-thick layer of increased acoustic backscatter near the top of the hydrothermal plume at 1.9 km depth (Thomson et al., 1991, Burd et al...zooplankton migrate vertically between the upper ocean and the hydrothermal plume (Burd & Thomson, 1994). This interpretation is consistent with a

Continuing Investigations of the Relationship between Fin Whales, Zooplankton Concentrations and Hydrothermal Venting on the Juan de Fuca Ridge

DTIC Science & Technology

2012-09-30

Fuca Ridge. Our goal is to understand the influences of globally distributed hydrothermal plumes on the trophic ecology of the deep ocean...a layer of increased acoustic backscatter near the top of the hydrothermal plume (Thomson et al., 1991; Burd et al., 1992), leading to the inference...shallow species which presumably migrate vertically between the upper ocean and the hydrothermal plume (Burd and Thomson, 1994, 1995). Our approach is

Physiological preparedness and performance of Atlantic salmon Salmo salar smolts in relation to behavioural salinity preferences and thresholds

USGS Publications Warehouse

Stich, D.S.; Zydlewski, G.B.; Zydlewski, Joseph D.

2015-01-01

This study investigated the relationships between behavioural responses of Atlantic salmon Salmo salarsmolts to saltwater (SW) exposure and physiological characteristics of smolts in laboratory experiments. It concurrently described the behaviour of acoustically tagged smolts with respect to SW and tidal cycles during estuary migration. Salmo salar smolts increased their use of SW relative to fresh water (FW) from April to June in laboratory experiments. Mean preference for SW never exceeded 50% of time in any group. Preference for SW increased throughout the course of smolt development. Maximum continuous time spent in SW was positively related to gill Na+, K+-ATPase (NKA) activity and osmoregulatory performance in full-strength SW (measured as change in gill NKA activity and plasma osmolality). Smolts decreased depth upon reaching areas of the Penobscot Estuary where SW was present, and all fish became more surface oriented during passage from head of tide to the ocean. Acoustically tagged, migrating smolts with low gill NKA activity moved faster in FW reaches of the estuary than those with higher gill NKA activity. There was no difference in movement rate through SW reaches of the estuary based on gill NKA activity. Migrating fish moved with tidal flow during the passage of the lower estuary based on the observed patterns in both vertical and horizontal movements. The results indicate that smolts select low-salinity water during estuary migration and use tidal currents to minimize energetic investment in seaward migration. Seasonal changes in osmoregulatory ability highlight the importance of the timing of stocking and estuary arrival.

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction.

PubMed

Cohen, Daniel J; Gloerich, Martijn; Nelson, W James

2016-12-20

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell-cell adhesions and reorganize from the front-rear polarity characteristic of cell migration to the apical-basal polarity of an epithelium. However, identifying the "stop signal" that induces colliding tissues to cease migrating and heal remains an open question. Epithelial cells form integrin-based adhesions to the basal extracellular matrix (ECM) and E-cadherin-mediated cell-cell adhesions on the orthogonal, lateral surfaces between cells. Current biological tools have been unable to probe this multicellular 3D interface to determine the stop signal. We addressed this problem by developing a unique biointerface that mimicked the 3D organization of epithelial cell adhesions. This "minimal tissue mimic" (MTM) comprised a basal ECM substrate and a vertical surface coated with purified extracellular domain of E-cadherin, and was designed for collision with the healing edge of an epithelial monolayer. Three-dimensional imaging showed that adhesions formed between cells, and the E-cadherin-coated MTM resembled the morphology and dynamics of native epithelial cell-cell junctions and induced the same polarity transition that occurs during epithelial self-healing. These results indicate that E-cadherin presented in the proper 3D context constitutes a minimum essential stop signal to induce self-healing. That the Ecad:Fc MTM stably integrated into an epithelial tissue and reduced migration at the interface suggests that this biointerface is a complimentary approach to existing tissue-material interfaces.

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction

PubMed Central

Cohen, Daniel J.; Gloerich, Martijn; Nelson, W. James

2016-01-01

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell–cell adhesions and reorganize from the front-rear polarity characteristic of cell migration to the apical-basal polarity of an epithelium. However, identifying the "stop signal" that induces colliding tissues to cease migrating and heal remains an open question. Epithelial cells form integrin-based adhesions to the basal extracellular matrix (ECM) and E-cadherin–mediated cell–cell adhesions on the orthogonal, lateral surfaces between cells. Current biological tools have been unable to probe this multicellular 3D interface to determine the stop signal. We addressed this problem by developing a unique biointerface that mimicked the 3D organization of epithelial cell adhesions. This "minimal tissue mimic" (MTM) comprised a basal ECM substrate and a vertical surface coated with purified extracellular domain of E-cadherin, and was designed for collision with the healing edge of an epithelial monolayer. Three-dimensional imaging showed that adhesions formed between cells, and the E-cadherin-coated MTM resembled the morphology and dynamics of native epithelial cell–cell junctions and induced the same polarity transition that occurs during epithelial self-healing. These results indicate that E-cadherin presented in the proper 3D context constitutes a minimum essential stop signal to induce self-healing. That the Ecad:Fc MTM stably integrated into an epithelial tissue and reduced migration at the interface suggests that this biointerface is a complimentary approach to existing tissue–material interfaces. PMID:27930308

Complex behaviour in complex terrain - Modelling bird migration in a high resolution wind field across mountainous terrain to simulate observed patterns.

PubMed

Aurbach, Annika; Schmid, Baptiste; Liechti, Felix; Chokani, Ndaona; Abhari, Reza

2018-06-03

Crossing of large ecological barriers, such as mountains, is in terms of energy considered to be a demanding and critical step during bird migration. Besides forming a geographical barrier, mountains have a profound impact on the resulting wind flow. We use a novel framework of mathematical models to investigate the influences of wind and topography on nocturnal passerine bird behaviour, and to assess the energy costs for different flight strategies for crossing the Jura Mountains. The mathematical models include three biological models of bird behaviour: i) wind drift compensation; ii) adaptation of flight height for favourable winds; and, iii) avoidance of obstacles (cross over and/or circumvention of an obstacle following a minimum energy expenditure strategy), which are assessed separately and in combination. Further, we use a mesoscale weather model for high-resolution predictions of the wind fields. We simulate the broad front nocturnal passerine migration for autumn nights with peak migration intensities. The bird densities retrieved from a weather radar are used as the initial intensities and to specify the vertical distributions of the simulated birds. It is shown that migration over complex terrain represents the most expensive flight option in terms of energy expenditure, and wind is seen to be the main factor that influences the energy expenditure in the bird's preferred flight direction. Further, the combined effects of wind and orography lead to a high concentration of migratory birds within the favourable wind conditions of the Swiss lowlands and north of the Jura Mountains. Copyright © 2018 Elsevier Ltd. All rights reserved.

Excitation mechanism of non-migrating tides

NASA Astrophysics Data System (ADS)

Miyoshi, Yasunobu; Pancheva, Dora; Mukhtarov, Plamen; Jin, Hidekatsu; Fujiwara, Hitoshi; Shinagawa, Hiroyuki

2017-04-01

Using an atmosphere-ionosphere coupled model, the excitation source and temporal (seasonal and interannual) variations in non-migrating tides are investigated in this study. We first focus our attention on temporal variations in eastward moving diurnal tide with zonal wavenumber 3 (DE3), which is the largest of all the non-migrating tides in the mesosphere and lower thermosphere (MLT). Our simulation results indicate that upward propagation of the DE3 excited in the troposphere is sensitive to the zonal mean zonal wind in the stratosphere and mesosphere. The DE3 amplitude is enhanced in the region where the vertical shear of the zonal mean zonal wind is positive (westerly shear). Quasi-2-year variation in the DE3 amplitude in the MLT region is generated by quasi-2-year variation in the zonal mean zonal wind between 40 and 70 km, which is modulated by the stratospheric QBO. The excitation mechanisms of SW3 (westward moving semidiurnal tide with zonal wavenumber 3) and SW1 (westward moving semidiurnal tide with zonal wavenumber 1) are also investigated. During equinoxes, the SW3 and SW1 are excited by tropospheric heating (latent heat release and solar radiative heating) associated with cumulus convection in the tropics, and propagate upward into the MLT region. On the other hand, during solstices, SW3 and SW1 are generated in the winter stratosphere and mesosphere through the nonlinear interaction between the stationary planetary wave and migrating semidiurnal tide, and propagate upward to the lower thermosphere. The excitation sources of other non-migrating tides are also discussed.

Analysis of CO2 trapping capacities and long-term migration for geological formations in the Norwegian North Sea using MRST-co2lab

NASA Astrophysics Data System (ADS)

Møll Nilsen, Halvor; Lie, Knut-Andreas; Andersen, Odd

2015-06-01

MRST-co2lab is a collection of open-source computational tools for modeling large-scale and long-time migration of CO2 in conductive aquifers, combining ideas from basin modeling, computational geometry, hydrology, and reservoir simulation. Herein, we employ the methods of MRST-co2lab to study long-term CO2 storage on the scale of hundreds of megatonnes. We consider public data sets of two aquifers from the Norwegian North Sea and use geometrical methods for identifying structural traps, percolation-type methods for identifying potential spill paths, and vertical-equilibrium methods for efficient simulation of structural, residual, and solubility trapping in a thousand-year perspective. In particular, we investigate how data resolution affects estimates of storage capacity and discuss workflows for identifying good injection sites and optimizing injection strategies.

Westward migration of tropical cyclone rapid-intensification over the Northwestern Pacific during short duration El Niño.

PubMed

Guo, Yi-Peng; Tan, Zhe-Min

2018-04-17

The El Niño-Southern Oscillation (ENSO) can significantly affect the rapid intensification of tropical cyclones over the western North Pacific (WNP). However, ENSO events have various durations, which can lead to different atmospheric and oceanic conditions. Here we show that during short duration El Niño events, the WNP tropical cyclone rapid-intensification mean occurrence position migrates westward by ~8.0° longitude, which is caused by reduced vertical wind shear, increased mid-tropospheric humidity, and enhanced tropical cyclone heat potential over the westernmost WNP. The changes in these factors are caused by westward advected upper ocean heat during the decaying phase of a short duration El Niño. As super El Niño events tend to have short durations and their frequency is projected to increase under global warming, our findings have important implications for future projections of WNP tropical cyclone activity.

Survival and behavioral effects of exposure to a hydrokinetic turbine on juvenile Atlantic salmon and adult American shad

USGS Publications Warehouse

Castro-Santos, Theodore R.; Haro, Alex

2015-01-01

This paper describes a series of experiments designed to measure the effect of exposure to a full-scale, vertical axis hydrokinetic turbine on downstream migrating juvenile Atlantic salmon (N=75) and upstream migrating adult American shad (N=208). Controlled studies were performed in a large-scale, open-channel flume, and all individuals approached the turbine under volitional control. No injuries were observed, and there was no measurable increase in mortality associated with turbine passage. Exposure to the turbine elicited behavioral responses from both species, however, with salmon passing primarily over the downrunning blades. Shad movement was impeded by the device, as indicated by fewer attempts of shorter duration and reduced distance of ascent up the flume. More work should be performed in both laboratory and field conditions to determine to what extent these effects are likely to influence free-swimming fish.

Heating-induced phase transformation in zeolite brewsterite: new 4- and 5-coordinated (Si,Al) sites

NASA Astrophysics Data System (ADS)

Alberti, A.; Sacerdoti, M.; Quartieri, S.; Vezzalini, G.

The dehydration-rehydration processes and phase transformations of brewsterite (space group P21/m, ideal formula (Sr,Ba)Al2Si6O16.5H2O) were studied by single crystal X-ray diffraction on two samples heated in an evacuated capillary for 24 h at 280°C and 330°C, respectively, and then cooled to room temperature. After the data collection, the capillary of the crystal heated at 280°C was broken, the sample was kept at room conditions for one month, and diffraction data were recollected. Brewsterite heated in vacuum at 280°C shows a strong decrease of the unit cell volume (about 10%) and the statistical breaking of the T1-O7-T2 bridge of the 4-ring of the 4254 PBU. T1 cation, in 31% of cases, migrates to a new tetrahedral site, which shares three vertices with the previously occupied one; the fourth vertex is on the mirror plane, and joins two adjacent layers. T2 cation, in 20% of cases, migrates to a new site, which is characterized by a 5-fold coordination. This coordination polyhedron shares three vertices with the previously occupied tetrahedron; the fourth vertex is on the mirror plane, and joins two adjacent layers; the fifth one is unshared. The formation of these new T-O-T bridges prevents the re-expansion and rehydration of the heated brewsterite; as a consequence, the crystal brought back to room conditions does not show any noticeable structural difference with respect to that heated at 280°C. The exchangeable cations, which occupy only one extraframework site in the untreated brewsterite, spread over several sites. The sample heated at 330°C shows a further decrease in the unit cell volume of about 2% with respect to the sample heated at 280°C, and an increase in the migration percentage of T1 and T2 cations to the new sites.

Do larvae from deep-sea hydrothermal vents disperse in surface waters?

PubMed

Yahagi, Takuya; Kayama Watanabe, Hiromi; Kojima, Shigeaki; Kano, Yasunori

2017-06-01

Larval dispersal significantly contributes to the geographic distribution, population dynamics, and evolutionary processes of animals endemic to deep-sea hydrothermal vents. Little is known as to the extent that their larvae migrate vertically to shallower waters and experience stronger currents and richer food supplies. Here, we first provide evidence from early life-history traits and population genetics for the surface dispersal of a vent species. Planktotrophic larvae of a red blood limpet, Shinkailepas myojinensis (Gastropoda: Neritimorpha: Phenacolepadidae), were cultured to observe their swimming behavior and to evaluate the effects of temperature on survival and growth. In addition, the population structure was analyzed based on 1.2-kbp mitochondrial DNA sequences from 77 specimens that cover the geographic and bathymetric distributions of the species (northwest Pacific, 442-1,227 m in depth). Hatched larvae constantly swam upward at 16.6-44.2 mm/min depending on temperature. Vertical migration from hydrothermal vents to the surface, calculated to take ~4-43 d, is attainable given their lengthy survival time without feeding. Fed larvae best survived and grew at 25°C (followed by 20°C), which approximates the sea surface temperature in the geographic range of the species. Little or no growth was observed at the temperature of the vent habitat where adult limpets occur (≤15°C). Population genetic analyses showed no differentiation among localities that are <1,350 km apart. The larvae of S. myojinensis most likely migrate to the surface water, where high phytoplankton biomass and strong currents enable their growth and long distance dispersal over many months. Sea surface temperature may represent a critical factor in determining the geographic distribution of many vent endemic species with a planktotrophic early development, and in turn the faunal composition of individual vent sites and regions. © 2017 by the Ecological Society of America.

Pteropod Ecology and Physiology in Relation to Natural Variability in Carbonate Chemistry

NASA Astrophysics Data System (ADS)

Lawson, G. L.; Maas, A. E.; Wang, A. Z.; Bergan, A. J.; Wiebe, P. H.; Blanco-Bercial, L.; Lavery, A.; Copley, N. J.

2016-02-01

The thecosomatous pteropods are a group of aragonite-shelled zooplankton thought to be particularly vulnerable to ocean acidification. We seek to gain insight into both basic questions of pteropod biology and potential responses to ocean acidification by combining field sampling with shipboard experimental manipulations, capitalizing on natural spatial variability in modern-day carbonate chemistry between and within the Atlantic and Pacific Oceans. Two cruises were conducted, in 2011 and 2012, along open-ocean transects running between 35 and 50°N in the NW Atlantic and NE Pacific; strong differences in environmental conditions exist between these regions, as well as along the Pacific transect, notably in aragonite compensation and oxygen minimum depths. The transects overlapped with portions of WOCE/CLIVAR lines A20 and P17N and measurements of carbonate chemistry provided insight into rates of chemical change as well as information on the pteropods' chemical environment. The abundance and diversity of pteropods varied substantially within and between the study regions. Depth-stratified net sampling during day and night indicated that multiple pteropod species undertook the typical diel vertical migration employed by many zooplankton species as an anti-predation strategy; the amplitude of this migration differed among species as well as within sub-populations of certain cosmopolitan species found in both oceans. Shipboard experiments of short-duration (<18 hrs, intended to mimic the duration of diel vertical migrations to depth) exposing eight species of pteropod to high CO2 and low O2 found no effect of CO2 alone on metabolic rate and an effect of low O2 or interactive effect of CO2 and O2 only in two Atlantic species not known to naturally encounter low oxygen in their biogeographic range. The implications of these various findings to our understanding of the response of pteropods to environmental change will be discussed.

Contemporary Surface Seasonal Oscillation and Vertical Deformation in Tibetan Plateau and Nepal Derived from the GPS, Leveling and GRACE Data

NASA Astrophysics Data System (ADS)

Shen, W.; Pan, Y.; Hwang, C.; Ding, H.

2015-12-01

We use 168 Continuous Global Positioning System (CGPS) stations distributed in the Tibetan Plateau (TP) and Nepal from lengths of 2.5 to 14 years to estimate the present-day velocity field in this area, including the horizontal and vertical deformations under the frame ITRF2008. We estimate and remove common mode errors in regional GPS time series using the principal component analysis (PCA), obtaining a time series with high signal to noise ratio. Following the maximum estimation analysis, a power law plus white noise stochastic model are adopted to estimate the velocity field. The highlight of Tibetan region is the crust vertical deformation. GPS vertical time series present seasonal oscillations caused by temporal mass loads, hence GRACE data from CSR are used to study the mass loads change. After removing the mass load deformations from GPS vertical rates, the results are improved. Leveling data about 48 years in this region are also used to estimate the rates of vertical movements. Our study suggests that the boundary of south Nepal is still sinking due to the fact that the India plate is crashing into the Eurasian plate. The uplift rates from south to north of TP reduce gradually. Himalayas region and north Nepal uplift around 6 mm/yr in average. The uplift rate along East TP in Qinhai is around 2.7 mm/yr in average. In contrast, the southeast of Tibetan Plateau, south Yunnan and Tarim in Xinjiang sink with different magnitudes. Our observation results suggest complicated mechanism of the mass migration in TP. This study is supported by National 973 Project China (grant Nos. 2013CB733302 and 2013CB733305), NSFC (grant Nos. 41174011, 41429401, 41210006, 41128003, 41021061).

Characterizing seasonal and diel vertical movement and habitat use of lake whitefish (Coregonus clupeaformis) in Clear Lake, Maine

USGS Publications Warehouse

Zydlewski, Joseph D.; Gorsky, Dimitry; Balsey, David

2016-01-01

Seasonal and daily vertical activity of lake whitefish Coregonus clupeaformis was studied in Clear Lake, Maine (253 ha), using acoustic telemetry from November 2004 to June 2009. Twenty adult lake whitefish were tagged with acoustic tags that had either a depth sensor or both depth and temperature sensors to assess vertical habitat use at a seasonal and daily resolution. Vertical habitat selection varied seasonally and was strongly influenced by temperature. Between December and April, when the lake was covered with ice, surface temperature was below 2°C and tagged individuals occupied deep areas of the lake (∼15 m). After ice-out, fish ascended into shallow waters (∼5 m), responding to increased water temperature and possibly to greater foraging opportunity. When surface water temperatures exceeded 20°C, fish descended below the developing thermocline (∼9 m), where they remained until surface temperatures fell below 20°C; fish then ascended into shallower depths, presumably for feeding and spawning. Through the winter, fish remained in thermal habitats that were warmer than the surface temperatures; in the summer, they selected depths with thermal habitats below 15°C. Though the amplitude varied greatly across seasons, lake whitefish displayed a strong diurnal pattern of activity as measured by vertical velocities. Fish were twofold more active during spring, summer, and fall than during winter. Lake whitefish exhibited diel vertical migrations, rising in the water column during nighttime and occupying deeper waters during the day. This pattern was more pronounced in the spring and fall and far less prominent during winter and summer. The strong linkage between temperature and habitat use may limit the current range of lake whitefish and may be directly impacted by climatic change.

Volcanic signatures in time gravity variations during the volcanic unrest on El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Sainz-Maza Aparicio, S.; Arnoso Sampedro, J.; Gonzalez Montesinos, F.; Martí Molist, J.

2014-06-01

Gravity changes occurring during the initial stage of the 2011-2012 El Hierro submarine eruption are interpreted in terms of the preeruptive signatures during the episode of unrest. Continuous gravity measurements were made at two sites on the island using the relative spring gravimeter LaCoste and Romberg gPhone-054. On 15 September 2011, an observed gravity decrease of 45 μGal, associated with the southward migration of seismic epicenters, is consistent with a lateral magma migration that occurred beneath the volcanic edifice, an apparently clear precursor of the eruption that took place 25 days later on 10 October 2011. High-frequency gravity signals also appeared on 6-11 October 2011, pointing to an occurring interaction between a magmatic intrusion and the ocean floor. These important gravity changes, with amplitudes varying from 10 to -90 μGal, during the first 3 days following the onset of the eruption are consistent with the northward migration of the eruptive focus along an active eruptive fissure. An apparent correlation of gravity variations with body tide vertical strain was also noted, which could indicate that concurrent tidal triggering occurred during the initial stage of the eruption.

Shaping Disk Galaxy Stellar Populations via Internal and External Processes

NASA Astrophysics Data System (ADS)

Roškar, Rok

2015-03-01

In recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

The role of the US Great Plains low-level jet in nocturnal migrant behavior

NASA Astrophysics Data System (ADS)

Wainwright, Charlotte E.; Stepanian, Phillip M.; Horton, Kyle G.

2016-10-01

The movements of aerial animals are under the constant influence of atmospheric flows spanning a range of spatiotemporal scales. The Great Plains nocturnal low-level jet is a large-scale atmospheric phenomenon that provides frequent strong southerly winds through a shallow layer of the airspace. The jet can provide substantial tailwind assistance to spring migrants moving northward, while hindering southward migration during autumn. This atmospheric feature has been suspected to play a prominent role in defining migratory routes, but the flight strategies used with respect to these winds are yet to be examined. Using collocated vertically pointing radar and lidar, we investigate the altitudinal selection behavior of migrants over Oklahoma during two spring and two autumn migration seasons. In general, migrants choose to fly within the jet in spring, often concentrating in the favorable wind speed maximum. Autumn migrants typically fly below the jet, although some will rapidly climb to reach altitudes above the inhibiting winds. The intensity of migration was relatively constant throughout the spring due to the predominantly favorable southerly jet winds. Conversely, autumn migrants were more apt to delay departure to wait for the relatively infrequent northerly winds.

Leachate Properties and Cadmium Migration Through Freeze-thaw Treated Soil Columns.

PubMed

Xu, Meng; Zheng, Yue; Chen, Weiwei; Mao, Na; Guo, Ping

2017-01-01

Soil column leaching experiments were conducted to study the effects of multiple freeze-thaw cycles on the vertical migration of cadmium (Cd). Three Cd-spiked leaching solutions of different properties were derived from snowmelt, sludge, and straw, designated as B, W and J, respectively. The leaching solutions varied in dissolved organic matter (DOM) concentrations in the order of J > W > B. Changes in leachate properties and Cd concentration were observed. The results showed that pH values of all the leachate solutions through freeze-thaw treated soil columns were higher than those of leachates through unfrozen soils. However, electrical conductivity (EC) values decreased compared with leachates in unfrozen treated soil columns. Although the concentrations of DOM in leachate solutions had no evident differences between the freeze-thaw and unfrozen treated soil columns, the concentrations of DOM in the leachate solutions B, W and J were different. Freeze-thaw cycles resulted in increased concentrations of Cd in the leachate solutions in the order J > W > B, and promoted a deeper migration of Cd in the soil columns. Thus, it was shown that freeze-thaw cycles may increase the risk of groundwater pollution by Cd.

A Numerical Modeling Study of Mesodinium Bloom Formation and Retention in a River-Dominated Mesotidal Estuary

NASA Astrophysics Data System (ADS)

Spitz, Y. H.; Cervantes, B.

2016-02-01

The Columbia River estuary experiences extensive seasonal red-colored blooms caused by a mixotrophic ciliate of the genus Mesodinium. Although the blooms are non-toxic, they have a significant influence on the levels of nutrients, light and oxygen in the estuary. Mesodinium spp. displays very particular physiology that makes it one of few planktonic species able to thrive in a highly flushed system: a high growth rate due to its ability to photosynthesize using the photosynthetic organelles of its preys, and complex vertical migration patterns. Knowledge of the migration pattern is based on limited observations of Mesodinium behavior in culture and recent in-situ measurements collected in the Columbia River estuary. A more comprehensive understanding is needed of the mechanisms allowing Mesodinium spp. to be retained and experience rapid growth. To this end, we extended the finite element circulation model SELFE to include a 5-component behavioral model that simulates the relationships between nutrients, detritus, Mesodinium spp. and its cryptophyte prey. We then used the model to investigate various migration patterns and growth scenarios to determine their role in the formation and retention of the Mesodinium spp. bloom in the brackish water of the estuary.

Late Quaternary river channel migrations of the Kura River in Transcaucasia - tectonic versus climatic causes

NASA Astrophysics Data System (ADS)

von Suchodoletz, Hans; Gärtner, Andreas; Hoth, Silvan; Umlauft, Josefine; Godoladze, Tea; Faust, Dominik

2015-04-01

Large-scale river channel migrations either in the form of avulsions or combing, i.e. progressive lateral migrations, are global phenomena during the Late Quaternary. Such channel migrations were triggered by tectonics, climate change, human activity or a combination of those factors. River channel migrations have the potential to cause significant human and economic losses. Thus, a more thorough knowledge about underlying causes and process rates is essential. Furthermore, such studies will elucidate the sensitivity or robustness of rivers to different external and internal forcing-agents, i.e. they help to identify the dominant drivers of regional landscape evolution. The Caucasus region is part of the active collision zone between the Africa-Arabian and the Eurasian plates, and is characterized by high current tectonic activity. Furthermore, significant environmental changes took place during the Late Quaternary, i.e. the shrinking or even disappearance of glaciers in the Greater and Lesser Caucasus or fundamental changes of the vegetation cover varying between woodland and grassland-dominated vegetation. The Kura River is the main gaining stream of the Transcaucasian Depression located between the Greater Caucasus Mountains in the north and the Lesser Caucasus Mountains in the south, and receives several tributaries from both mountain ranges. This study focusses on the middle course of the Kura River in eastern Georgia, SE of the city of Tbilisi. Integration of fluvial geomorphology, geochronology, heavy mineral analyses and seismo-tectonic analyses demonstrates that this part of the Kura River underwent large-scale channel migrations up to >10 km during Late Pleistocene and Holocene. It is interpreted that these movements followed both tectonic and climatic triggers: Whereas SW-ward migrations were caused by tectonic uplift in and SW-directed advance of the Kura fold and thrust belt as part of the Greater Caucasus, NE-ward migrations occurred during cold glacial periods with intensive sediment supply and strong vertical sedimentation of tributaries originating from a westerly direction. Thus, the middle course of the Kura River shows a dynamic equilibrium between competing tectonic and climatic processes.

Imaging Fracking Zones by Microseismic Reverse Time Migration for Downhole Microseismic Monitoring

NASA Astrophysics Data System (ADS)

Lin, Y.; Zhang, H.

2015-12-01

Hydraulic fracturing is an engineering tool to create fractures in order to better recover oil and gas from low permeability reservoirs. Because microseismic events are generally associated with fracturing development, microseismic monitoring has been used to evaluate the fracking process. Microseismic monitoring generally relies on locating microseismic events to understand the spatial distribution of fractures. For the multi-stage fracturing treatment, fractures created in former stages are strong scatterers in the medium and can induce strong scattering waves on the waveforms for microseismic events induced during later stages. In this study, we propose to take advantage of microseismic scattering waves to image fracking zones by using seismic reverse time migration method. For downhole microseismic monitoring that involves installing a string of seismic sensors in a borehole near the injection well, the observation geometry is actually similar to the VSP (vertical seismic profile) system. For this reason, we adapt the VSP migration method for the common shot gather to the common event gather. Microseismic reverse-time migration method involves solving wave equation both forward and backward in time for each microseismic event. At current stage, the microseismic RTM is based on 2D acoustic wave equation (Zhang and Sun, 2008), solved by the finite-difference method with PML absorbing boundary condition applied to suppress the reflections of artificial boundaries. Additionally, we use local wavefield decomposition instead of cross-correlation imaging condition to suppress the imaging noise. For testing the method, we create a synthetic dataset for a downhole microseismic monitoring system with multiple fracking stages. It shows that microseismic migration using individual event is able to clearly reveal the fracture zone. The shorter distance between fractures and the microseismic event the clearer the migration image is. By summing migration images for many events, it can better reveal the fracture development during the hydraulic fracturing treatment. The synthetic test shows that microseismic migration is able to characterize the fracturing zone along with microseismic events. We will extend the method from 2D to 3D as well as from acoustic to elastic and apply it to real microseismic data.

Dive patterns of tagged right whales in the Great South Channel

NASA Astrophysics Data System (ADS)

Winn, Howard E.; Goodyear, Jeffrey D.; Kenney, Robert D.; Petricig, Richard O.

Right whales were tagged in 1988 and 1989 with radio and sonic telemetry tags as part of a multidisciplinary investigation of right whales and their habitat in the Great South Channel region east of Cape Cod. The tags yielded data on the durations of 6456 dives and 6482 surfacings, as well as 23,538 measurements of the depth of a diving whale. Log-survivorship analysis of the 1988 data showed a clear separation between the durations of dives between blows within a single surfacing sequence or bout (intea-bout dives) and longer dives between surfacing sequences (interbout dives) at 27 s, which was also applied to the 1989 data. Inter-bout dives averaged 127.3 s, and were significantly longer in 1988 than in 1989. Inter-bout dives were significantly longer during the day than night in 1988, and longer at night in 1989. The average intea-bout dive duration was 11.8 s, with 1989 dives longer than those in 1988. Surface durations averaged 6.2 s, and were also significantly longer in 1989. Dive depths were recorded only in 1989. Mean dive depth was 7.3 m, and only 12 dives went deeper than 30 m. The typical right whale dive pattern in 1988 included relatively short surfacings, long dives during the day, and shorter dives at night. This correlated with strong diel vertical migration by the dense zooplankton patches on which they were presumed to be feeding based on indirect evidence-from near the surface at night to near the bottom during the day. The 1989 pattern included longer dives during the night, as well as some exceptionally long surfacings. Zooplankton in 1989 did not migrate vertically, and remained near the surface day and night in right whale feeding areas. Right whale dive patterns in the Great South Channel are closely correlated with the horizontal and vertical distributions and movements of dense patches of their zooplankton prey.

Diel variation in the vertical distribution of deep-water scattering layers in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

D'Elia, Marta; Warren, Joseph D.; Rodriguez-Pinto, Ivan; Sutton, Tracey T.; Cook, April; Boswell, Kevin M.

2016-09-01

Sound scattering layers (SSLs) are important components of oceanic ecosystems with ubiquitous distribution throughout the world's oceans. This vertical movement is an important mechanism for exchanging organic matter from the surface to the deep ocean, as many of the organisms comprising SSLs serve as prey resources for linking the lower trophic levels to larger predators. Variations in abundance and taxonomic composition of mesopelagic organisms were quantified using repeated discrete net sampling and acoustics over a 30-h survey, performed during 26-27 June 2011 at single site (27°28'51;N and 88°27'54;W) in the northern Gulf of Mexico. We acoustically classified the mesopelagic SSL into four broad taxonomic categories, crustacean and small non-swimbladdered fish (CSNSBF), large non-swimbladdered fish (LNSBF), swimbladdered fish (SBF) and unclassified and we quantified the abundance of mesopelagic organisms over three discrete depth intervals; epipelagic (0-200 m); upper mesopelagic (200-600 m) and lower mesopelagic (600-1000 m). Irrespective of the acoustic categories at dusk part of the acoustic energy redistributed from the mesopelagic into the upper epipelagic (shallower than 100 m) remaining however below the thermocline depth. At night higher variability in species composition was observed between 100 and 200 m suggested that a redistribution of organisms may also occur within the upper portion of the water column. Along the upper mesopelagic backscatter spectra from CSNSBF migrated between 400 and 460 m while spectra from the other categories moved to shallower depths (300 and 350 m), resulting in habitat separation from CSNSBF. Relatively small vertical changes in both acoustic backscatter and center of mass metrics of the deep mesopelagic were observed for CNSBF and LNSBF suggesting that these animals may be tightly connected to deeper (below 1000 m) mesopelagic habitats, and do not routinely migrate into the epipelagic.

Correlative velocity fluctuations over a gravel river bed

USGS Publications Warehouse

Dinehart, Randal L.

1999-01-01

Velocity fluctuations in a steep, coarse‐bedded river were measured in flow depths ranging from 0.8 to 2.2 m, with mean velocities at middepth from 1.1 to 3.1 m s−1. Analyses of synchronous velocity records for two and three points in the vertical showed a broad range of high coherence for wave periods from 10 to 100 s, centering around 10–30 s. Streamwise correlations over distances of 9 and 14 m showed convection velocities near mean velocity for the same wave periods. The range of coherent wave periods was a small multiple of predicted “boil” periods. Correlative fluctuations in synchronous velocity records in the vertical direction suggested the blending of short pulses into longer wave periods. The highest spectral densities were measured beyond the range of coherent wave periods and were probably induced by migration of low‐relief bed forms.

Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z-coordinate ocean model

NASA Astrophysics Data System (ADS)

Goldberg, D. N.; Snow, K.; Holland, P.; Jordan, J. R.; Campin, J.-M.; Heimbach, P.; Arthern, R.; Jenkins, A.

2018-05-01

Synchronous coupling is developed between an ice sheet model and a z-coordinate ocean model (the MITgcm). A previously-developed scheme to allow continuous vertical movement of the ice-ocean interface of a floating ice shelf ("vertical coupling") is built upon to allow continuous movement of the grounding line, or point of floatation of the ice sheet ("horizontal coupling"). Horizontal coupling is implemented through the maintenance of a thin layer of ocean ( ∼ 1 m) under grounded ice, which is inflated into the real ocean as the ice ungrounds. This is accomplished through a modification of the ocean model's nonlinear free surface evolution in a manner akin to a hydrological model in the presence of steep bathymetry. The coupled model is applied to a number of idealized geometries and shown to successfully represent ocean-forced marine ice sheet retreat while maintaining a continuous ocean circulation.

Evaluation of marsh development processes at Fire Island National Seashore: Recent and historic perspectives

USGS Publications Warehouse

Roman, C.T.; King, D.R.; Cahoon, D.R.; Lynch, J.C.; Appleby, P.G.

2007-01-01

Purpose and significance of the study: Salt marshes are dynamic environments, increasing in vertical elevation and migrating, often landward, as sea level rises. With sea level rise greater than marsh elevation increase, marshes can be submerged, marsh soils become waterlogged, and plant growth becomes stressed, often resulting in conversion of vegetation-dominated marsh to mudflat or open water habitat. Given that the rate of sea level rise is expected to accelerate over the next century and that some marshes in the northeast are becoming submerged (e.g., Jamaica Bay, NY), it is important to understand the processes that control marsh development. More specifically, the objectives of this project were to quantify vertical marsh elevation change in relation to recent rates of sea-level rise and to investigate factors or processes that are most influential in controlling the development and maintenance of Fire Island salt marshes.

Zooplankton Distribution in Four Western Norwegian Fjords

NASA Astrophysics Data System (ADS)

Gorsky, G.; Flood, P. R.; Youngbluth, M.; Picheral, M.; Grisoni, J.-M.

2000-01-01

A multi-instrumental array constructed in the Laboratoire d'Ecologie du Plancton Marin in Villefranche sur mer, France, named the Underwater Video Profiler (UVP), was used to investigate the vertical distribution of zooplankton in four western Norwegian fjords in the summer 1996. Six distinct zoological groups were monitored. The fauna included: (a) small crustaceans (mainly copepods), (b) ctenophores (mainly lobates), (c) siphonophores (mainly physonects), (d) a scyphomedusa Periphylla periphylla, (e) chaetognaths and (f) appendicularians. The use of the non-disturbing video technique demonstrated that the distribution of large zooplankton is heterogeneous vertically and geographically. Furthermore, the abundance of non-migrating filter feeders in the deep basins of the fjords indicates that there is enough food (living and non-living particulate organic matter) to support their dietary needs. This adaptation may be considered as a strategy for survival in fjords. Specifically, living in dark, deep water reduces visual predation and population loss encountered in the upper layer due to advective processes.

[Effects of fertilization method and nitrogen application rate on soil nitrogen vertical migration in a Populus xeuramericana cv. 'Guariento' plantation].

PubMed

Dai, Teng-fei; Xi, Ben-ye; Yan, Xiao-li; Jia, Li-ming

2015-06-01

A field experiment was conducted to investigate the effects of fertilization methods, i.e., drip (DF) and furrow fertilization (GF), and nitrogen (N) application rates (25, 50, 75 g N · plant(-1) · time(-1)) on the dynamics of soil N vertical migration in a Populus x euramericana cv. 'Guariento' plantation. The results showed that soil NH4(+)-N and NO3(-)-N contents decreased with the increasing soil depth under different fertilization methods and N application rates. In the DF treatment, soil NH4(+)-N and NO3(-)-N were mainly concentrated in the 0-40 cm soil layer, and their contents ascended firstly and then descended, reaching their maximum values at the 5th day (211.1 mg · kg(-1)) and 10th day (128.8 mg · kg(-1)) after fertilization, respectively. In the GF treatment, soil NH4(+)-N and NO3(-)-N were mainly concentrated in the 0-20 cm layer, and the content of soil NO3(-)-N rose gradually and reached its maximum at the 20th day (175.7 mg · kg(-1)) after fertilization, while the NH4(+)-N content did not change significantly after fertilization. Overall, N fertilizer had an effect within 20 days in the DF treatment, and more than 20 days in the GF treatment. In the DF treatment, the content and migration depth of soil NH4(+)-N and NO3(-)-N increased with the N application rate. In the GF treatment, the NO3(-)-N content increased with the N application rate, but the NH4(+)-N content was not influenced. Under the DF treatment, the hydrolysis rate, nitrification rate and migration depth of urea were higher or larger than that under the GF treatment, and more N accumulated in deep soil as the N application rate increased. Considering the distribution characteristics of fine roots and soil N, DF would be a better fertilization method in P. xeuramericana cv. 'Guariento' plantation, since it could supply N to larger distribution area of fine roots. When the N application rate was 50 g · tree(-1) each time, nitrogen mainly distributed in the zone of fine roots and had no risk of deep leaching, consequently improving the fertilizer utilization efficiency.

Flood Tide Transport of Blue Crab Postlarvae: Limitations in a Lagoonal Estuary

NASA Astrophysics Data System (ADS)

Cudaback, C.; Eggleston, D.

2005-05-01

Blue crabs, an important commercial species, spend much of their life in estuaries along the east coast. The larvae spawn at or near the ocean, but the juveniles mature in the lower salinity waters of the estuary. It is generally believed that blue crab postlarvae migrate into near surface waters on flood, possibly cued by increasing salinity, and return to the bottom on ebb. Over several tidal cycles, the postlarvae travel a significant distance up-estuary. This model applies quite well to Chesapeake Bay, which has a strong along-estuary salinity gradient and large tides, but may not apply as well to Pamlico Sound, where circulation and salinity are more wind-driven than tidal. A recently completed study (N. Reyns, PhD), indicates that postlarval blue crabs use flood tides and wind-driven currents to cross Pamlico Sound. This study was based on observations with good spatial coverage, but limited vertical and temporal resolution. We have recently completed a complementary study, sampling crab larvae around the clock at four depths at a single location. Preliminary results from the new study suggest that the crab postlarvae do swim all the way to the surface, on flood only, and that flood currents are strongest slightly below the surface. These observations suggest the utility of flood tide transport in this system. However, near bottom salinity does not seem to be driven by tides; at this point it is unclear what cue might trigger the vertical migration of the postlarvae.

Highly ordered vertical structure of Synechococcus populations within the one-millimeter-thick photic zone of a hot spring cyanobacterial mat

NASA Technical Reports Server (NTRS)

Ramsing, N. B.; Ferris, M. J.; Ward, D. M.

2000-01-01

A variety of contemporary techniques were used to investigate the vertical distribution of thermophilic unicellular cyanobacteria, Synechococcus spp., and their activity within the upper 1-mm-thick photic zone of the mat community found in an alkaline siliceous hot spring in Yellowstone National Park in Wyoming. Detailed measurements were made over a diel cycle at a 61 degrees C site. Net oxygenic photosynthesis measured with oxygen microelectrodes was highest within the uppermost 100- to 200-microm-thick layer until midmorning, but as the day progressed, the peak of net activity shifted to deeper layers, stabilizing at a depth of 300 microm from midday throughout the afternoon. Examination of vertical thin sections by bright-field and autofluorescence microscopy revealed the existence of different populations of Synechococcus which form discrete bands at different vertical positions. Denaturing gradient gel electrophoresis analysis of PCR-amplified 16S rRNA gene segments from horizontal cryosections obtained at 100-microm-thick vertical intervals also suggested vertical stratification of cyanobacterial, green sulfur bacterium-like, and green nonsulfur bacterium-like populations. There was no evidence of diel migration. However, image analysis of vertical thin sections revealed the presence of a narrow band of rod-shaped Synechococcus cells in which the cells assumed an upright position. These upright cells, located 400 to 800 microm below the surface, were observed only in mat samples obtained around noon. In mat samples obtained at other time points, the cells were randomly oriented throughout the mat. These combined observations reveal the existence of a highly ordered structure within the very thin photic zone of this hot spring microbial mat, consisting of morphologically similar Synechococcus populations that are likely to be differentially adapted, some co-occurring with green sulfur bacterium-like populations, and all overlying green nonsulfur bacterium-like populations.

Envisioning Urban Farming for Food Security during the Climate Change Era. Vertical Farm within Highly Urbanized Areas

NASA Astrophysics Data System (ADS)

Januszkiewicz, Krystyna; Jarmusz, Małgorzata

2017-10-01

Global climate change constitutes a serious threat to global security including food production in the following decades. This paper is focused on a new possibility and advisability of creating a systemic solution to resolve the problem of food security in highly-urbanized areas. The first part of the paper deal with historical development vertical farms ideas and defines the main environmental and spatial constrains also it indicates that vertical farms are going to be part of the future horticultural production. The second part presents results of the research program undertaken at West Pomeranian University of Technology in Szczecin by authors. The program goes on to attempt to solve the problem through architectural design. This study highlights an integrating large-scale horticultural production directly into the cities, where the most of the food consumption takes place. In conclusions emphasizes, that the design will force architects, engineers and urban planners to completely revise and redefine contemporary design process and understanding of the idea-fix of sustainable design. To successfully migrate food production from extensive rural areas to dense environment of city centres, a new holistic approach, integrating knowledge and advances of multiple fields of science, have to develop.

Maximizing oyster-reef growth supports green infrastructure with accelerating sea-level rise.

PubMed

Ridge, Justin T; Rodriguez, Antonio B; Joel Fodrie, F; Lindquist, Niels L; Brodeur, Michelle C; Coleman, Sara E; Grabowski, Jonathan H; Theuerkauf, Ethan J

2015-10-07

Within intertidal communities, aerial exposure (emergence during the tidal cycle) generates strong vertical zonation patterns with distinct growth boundaries regulated by physiological and external stressors. Forecasted accelerations in sea-level rise (SLR) will shift the position of these critical boundaries in ways we cannot yet fully predict, but landward migration will be impaired by coastal development, amplifying the importance of foundation species' ability to maintain their position relative to rising sea levels via vertical growth. Here we show the effects of emergence on vertical oyster-reef growth by determining the conditions at which intertidal reefs thrive and the sharp boundaries where reefs fail, which shift with changes in sea level. We found that oyster reef growth is unimodal relative to emergence, with greatest growth rates occurring between 20-40% exposure, and zero-growth boundaries at 10% and 55% exposures. Notably, along the lower growth boundary (10%), increased rates of SLR would outpace reef accretion, thereby reducing the depth range of substrate suitable for reef maintenance and formation, and exacerbating habitat loss along developed shorelines. Our results identify where, within intertidal areas, constructed or natural oyster reefs will persist and function best as green infrastructure to enhance coastal resiliency under conditions of accelerating SLR.

Light Modulation and Water Splitting Enhancement Using a Composite Porous GaN Structure.

PubMed

Yang, Chao; Xi, Xin; Yu, Zhiguo; Cao, Haicheng; Li, Jing; Lin, Shan; Ma, Zhanhong; Zhao, Lixia

2018-02-14

On the basis of the laterally porous GaN, we designed and fabricated a composite porous GaN structure with both well-ordered lateral and vertical holes. Compared to the plane GaN, the composite porous GaN structure with the combination of the vertical holes can help to reduce UV reflectance and increase the saturation photocurrent during water splitting by a factor of ∼4.5. Furthermore, we investigated the underlying mechanism for the enhancement of the water splitting performance using a finite-difference time-domain method. The results show that the well-ordered vertical holes can not only help to open the embedded pore channels to the electrolyte at both sides and reduce the migration distance of the gas bubbles during the water splitting reactions but also help to modulate the light field. Using this composite porous GaN structure, most of the incident light can be modulated and trapped into the nanoholes, and thus the electric fields localized in the lateral pores can increase dramatically as a result of the strong optical coupling. Our findings pave a new way to develop GaN photoelectrodes for highly efficient solar water splitting.

Spatial and vertical distribution of short chain chlorinated paraffins in soils from wastewater irrigated farmlands.

PubMed

Zeng, Lixi; Wang, Thanh; Han, Wenya; Yuan, Bo; Liu, Qian; Wang, Yawei; Jiang, Guibin

2011-03-15

Chlorinated paraffins (CPs) are one of the most complex groups of halogenated contaminants in the environment. However, studies of short chain CPs (SCCPs) in China are very scarce. In this study, the concentrations and distribution of SCCPs in farm soils from a wastewater irrigated area in China were investigated. SCCPs were detected in all topsoil samples, with the sum of the concentrations (ΣSCCPs) in the range of 159.9-1450 ng/g (dry weight, dw). A noticeable spatial trend and specific congener distribution were observed in the wastewater irrigated farmland. Soil vertical profiles showed that ΣSCCP concentrations below the plowed layer decreased exponentially and had a significant positive relationship (R(2) > 0.83) with total organic carbon in soil cores. Furthermore, soil vertical distributions indicated that lower chlorinated (Cl(5-6)) and shorter chain (C(10-12)) congeners are more prone to migrate to deeper soil layers compared to highly chlorinated and longer chain congeners. This work demonstrated that effluents from sewage treatment plants (STPs) could be a significant source of SCCPs to the ambient environment and wastewater irrigation can lead to higher accumulation of SCCPs in farm soils.

Variation in the diel vertical distributions of larvae and transforming stages of oceanic fishes across the tropical and equatorial Atlantic

NASA Astrophysics Data System (ADS)

Olivar, M. Pilar; Contreras, Tabit; Hulley, P. Alexander; Emelianov, Mikhail; López-Pérez, Cristina; Tuset, Víctor; Castellón, Arturo

2018-01-01

The vertical distributions of early developmental stages of oceanic fishes were investigated across the tropical and equatorial Atlantic, from oligotrophic waters close to the Brazilian coast to more productive waters close to the Mauritanian Upwelling Region. Stratification of the water column was observed throughout the study region. Fishes were caught with a MOCNESS-1 net with mouth area of 1 m2 at 11 stations. Each station was sampled both during the day and at night within a single 24-h period. The investigation covered both larvae and transforming stages from the surface to 800 m depth. Distribution patterns were analysed, and weighted mean depths for the larvae and transforming stages of each species were calculated for day and night conditions. Forty-seven different species were found. The highest number of species occurred in the three stations south of Cape Verde Islands, characterized by a mixture of South Atlantic Central Water (SACW) and Eastern North Atlantic Central Water (ENACW). There was a marked drop in species richness in the three stations closer to the African upwelling, dominated by ENACW. The highest abundances occurred in the families Myctophidae, Sternoptychidae, Gonostomatidae and Phosichthyidae. Day and night vertical distributions of larvae and transforming stages showed contrasting patterns, both in the depths of the main concentration layers in the water column, and in the diel migration patterns (where these were observed). Larvae generally showed a preference for the upper mixed layer (ca. 0-50 m) and upper thermocline (ca. 50-100 m), except for sternoptychids, which were also abundant in the lower thermocline layer (100-200 m) and even extended into the mesopelagic zone (down to 500 m). Transforming stages showed a more widespread distribution, with main concentrations in the mesopelagic zone (200-800 m). Larvae showed peak concentrations in the more illuminated and zooplankton-rich upper mixed layers during the day and a wider distribution through the upper 100 m during the night. For most species, transforming stages were concentrated in the mesopelagic layers both day and night, although in some species (Diaphus cf. vanhoeffeni and Vinciguerria nimbaria), the transforming stages displayed vertical migration into the upper 100 m at night, in a manner similar to their adult stages.

Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean.

PubMed

Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

2015-01-01

The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines-Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels ("v-eels") can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years.

Physiological preparedness and performance of Atlantic salmon Salmo salar smolts in relation to behavioural salinity preferences and thresholds.

PubMed

Stich, D S; Zydlewski, G B; Zydlewski, J D

2016-02-01

This study investigated the relationships between behavioural responses of Atlantic salmon Salmo salar smolts to saltwater (SW) exposure and physiological characteristics of smolts in laboratory experiments. It concurrently described the behaviour of acoustically tagged smolts with respect to SW and tidal cycles during estuary migration. Salmo salar smolts increased their use of SW relative to fresh water (FW) from April to June in laboratory experiments. Mean preference for SW never exceeded 50% of time in any group. Preference for SW increased throughout the course of smolt development. Maximum continuous time spent in SW was positively related to gill Na(+), K(+)-ATPase (NKA) activity and osmoregulatory performance in full-strength SW (measured as change in gill NKA activity and plasma osmolality). Smolts decreased depth upon reaching areas of the Penobscot Estuary where SW was present, and all fish became more surface oriented during passage from head of tide to the ocean. Acoustically tagged, migrating smolts with low gill NKA activity moved faster in FW reaches of the estuary than those with higher gill NKA activity. There was no difference in movement rate through SW reaches of the estuary based on gill NKA activity. Migrating fish moved with tidal flow during the passage of the lower estuary based on the observed patterns in both vertical and horizontal movements. The results indicate that smolts select low-salinity water during estuary migration and use tidal currents to minimize energetic investment in seaward migration. Seasonal changes in osmoregulatory ability highlight the importance of the timing of stocking and estuary arrival. © 2015 The Fisheries Society of the British Isles.

Migration of Amphitheater-Headed Valleys in Kauai Basalts: Wailua Falls as a Case Example

NASA Astrophysics Data System (ADS)

Pederson, D. T.; Blay, C.

2006-12-01

Amphitheater-headed valleys in Kauai basalts migrate upstream primarily because of weathering processes. Basalt weathering rates are enhanced by the presence of water and/or vegetation. When both weathering process are present, weathering rates are greater than the sum of the two processes. Because waterfalls can create an environment where vegetation growth is greatly inhibited by the impact of falling water, weathering rates may be much greater on each side of the falls where vegetation can grow. Sources of water for weathering include groundwater discharge, waterfall spray, and condensation of atmospheric water. Because basalts weather rapidly in tropical environments, streams require only the capability to transport smaller particle sizes to sustain amphitheater migration. It should be noted that most waterfalls occupy only a small fraction of the amphitheater head which further supports weathering as the principal agent in amphitheater development and migration. Lava flows building shield volcanos are usually episodic with crystallization and possible weathering occurring before the next flow. The rate of cooling of a flow determines the crystal size of minerals and in combination with the magma chemistry the susceptibility of a flow to weathering process as well as the strength of the rock. With time, soils and topography will develop on the now crystallized flow. Because clays are a product of basalt weathering, soils when buried by later flows, represent low permeability layers. Additionally, new flows may follow (and bury) surface drainage systems resulting in localized thicker flows that cool more slowly and have different properties then the adjacent thinner flows. Consequently, most amphitheater heads have significant heterogenieties, especially in a vertical section representing multiple basalt flows. Wailua Falls on Kauai will be used as a field example of amphitheater weathering processes and migration.

The diel migrations and distributions within a Mesopelagic community in the North East Atlantic. 1. Introduction and sampling procedures

NASA Astrophysics Data System (ADS)

Roe, H. S. J.; Angel, M. V.; Badcock, J.; Domanski, P.; James, P. T.; Pugh, P. R.; Thurston, M. H.

(i) This paper is an introduction to a series of papers describing the diel migrations and interrelationships of a mesopelagic community in the northeast Atlantic. (ii) The biological and physical background to the sampling area is described. (iii) There was little physical structure in the water column to a depth of 1000 m. (iv) The influence of Mediterranean water was detectable at varying depths between 550 and 800 m during the sampling programme. The possibility of mesoscale activity at these depths is discussed. (v) The sampling programme is described. Using the I.O.S. rectangular midwater trawl, the RMT 1 + 8, one hour samples were taken at 4 depth horizons, 100, 250, 450 and 600 m. Each depth was fished continuously for 48 hr. (vi) Additional non-quantitative surface samples, and surface light measurements were made throughout the RMT 1 + 8 sampling period. (vii) 97 hauls were made and the data for fish, decapod Crustacea, mysids, euphausiids, amphipods, copepods, ostracods, siphonophores, medusae, cteniphores and chaetognaths analysed. (viii) General results in terms of total numbers and numbers of species taken by the RMT 1 and the RMT 8 are described. (ix) The populations at 100 and 250 m showed more diel variation than those at 450 and 600 m, but the proportions of individual species and groups changed continuously at all depths. (x) These changes are due to diel vertical migrations. The migrations of most species only involved a part of their populations.

Gas hydrate reservoirs and gas migration mechanisms in the Terrebonne Basin, Gulf of Mexico

DOE PAGES

Hillman, Jess I. T.; Cook, Ann E.; Daigle, Hugh; ...

2017-07-27

Here, the interactions of microbial methane generation in fine-grained clay-rich sediments, methane migration, and gas hydrate accumulation in coarse-grained, sand-rich sediments are not yet fully understood. The Terrebonne Basin in the northern Gulf of Mexico provides an ideal setting to investigate the migration of methane resulting in the formation of hydrate in thin sand units interbedded with fractured muds. Using 3D seismic and well log data, we have identified several previously unidentified hydrate bearing units in the Terrebonne Basin. Two units are >100 m- thick fine-grained clay-rich units where gas hydrate occurs in near-vertical fractures. In some locations, these fine-grainedmore » units lack fracture features, and they contain 1-4-m thick hydrate bearing-sands. In addition, several other thin sand units were identified that contain gas hydrate, including one sand that was intersected by a well at the location of a discontinuous bottom-simulating reflector. Using correlation of well log data to seismic data, we have mapped and described these new units in detail across the extent of the available data, allowing us to determine the variation of seismic amplitudes and investigate the distribution of free gas and/or hydrate. We present several potential source-reservoir scenarios between the thick fractured mud units and thin hydrate bearing sands. We observe that hydrate preferentially forms within thin sand layers rather than fractures when sands are present in larger marine mud units. Based on regional mapping showing the patchy lateral extent of the thin sand layers, we propose that diffusive methane migration or short-migration of microbially generated methane from the marine mud units led to the formation of hydrate in these thin sands, as discontinuous sands would not be conducive to long-range migration of methane from deeper reservoirs.« less

Gas hydrate reservoirs and gas migration mechanisms in the Terrebonne Basin, Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillman, Jess I. T.; Cook, Ann E.; Daigle, Hugh

Here, the interactions of microbial methane generation in fine-grained clay-rich sediments, methane migration, and gas hydrate accumulation in coarse-grained, sand-rich sediments are not yet fully understood. The Terrebonne Basin in the northern Gulf of Mexico provides an ideal setting to investigate the migration of methane resulting in the formation of hydrate in thin sand units interbedded with fractured muds. Using 3D seismic and well log data, we have identified several previously unidentified hydrate bearing units in the Terrebonne Basin. Two units are >100 m- thick fine-grained clay-rich units where gas hydrate occurs in near-vertical fractures. In some locations, these fine-grainedmore » units lack fracture features, and they contain 1-4-m thick hydrate bearing-sands. In addition, several other thin sand units were identified that contain gas hydrate, including one sand that was intersected by a well at the location of a discontinuous bottom-simulating reflector. Using correlation of well log data to seismic data, we have mapped and described these new units in detail across the extent of the available data, allowing us to determine the variation of seismic amplitudes and investigate the distribution of free gas and/or hydrate. We present several potential source-reservoir scenarios between the thick fractured mud units and thin hydrate bearing sands. We observe that hydrate preferentially forms within thin sand layers rather than fractures when sands are present in larger marine mud units. Based on regional mapping showing the patchy lateral extent of the thin sand layers, we propose that diffusive methane migration or short-migration of microbially generated methane from the marine mud units led to the formation of hydrate in these thin sands, as discontinuous sands would not be conducive to long-range migration of methane from deeper reservoirs.« less

Occurrence and distribution of color and hydrogen sulfide in water of the principal artesian aquifers in the Valdosta area, Georgia

USGS Publications Warehouse

Krause, Richard E.

1976-01-01

Hydrogen sulfide and color occur in objectionable amounts in ground water from the principal artesian aquifer in the Valdosta , Ga., area. Generally, water from wells south of Valdosta is high in hydrogen sulfide; water from wells north of the city is high in color. Water with high sulfate is likely to be a problem in wells deeper than about 540 ft. Heavy pumpage concentrated in a small area may cause high-sulfate water to migrate vertically upward into shallower wells. (Woodard-USGS)

Walker Ranch 3D seismic images

DOE Data Explorer

Robert J. Mellors

2016-03-01

Amplitude images (both vertical and depth slices) extracted from 3D seismic reflection survey over area of Walker Ranch area (adjacent to Raft River). Crossline spacing of 660 feet and inline of 165 feet using a Vibroseis source. Processing included depth migration. Micro-earthquake hypocenters on images. Stratigraphic information and nearby well tracks added to images. Images are embedded in a Microsoft Word document with additional information. Exact location and depth restricted for proprietary reasons. Data collection and processing funded by Agua Caliente. Original data remains property of Agua Caliente.

Bioluminescence of Marine Dinoflagellates

PubMed Central

Seliger, H. H.; Fastie, W. G.; Taylor, W. R.; McElroy, W. D.

1962-01-01

Portable light-baffled underwater photometers have been designed for the measurement of dinoflagellate bioluminescence by day and night. Maximal light emission is obtained by mechanical stimulation in a defined volume. The pump which stimulates the dinoflagellates also constantly replenishes the sample volume so that continuous measurements are possible. Evidence for both diurnal variation and vertical migration is presented. Using luminous bacteria for calibration a single dinoflagellate has been found to emit of the order of 1010 light quanta per flash. The technique suggests that large scale mapping of bioluminescence is feasible. PMID:19873546

Siphonophores and the Deep Scattering Layer.

PubMed

Barham, E G

1963-05-17

Bathyscaphe dives in the San Diego Trough have revealed a close spatial relation between siphonophores and the deep scattering layer as recorded by precision depth recording echo-sounders. Measurements of gas bubbles within the flotation structures of Nanomia bijuga captured in a closing net in an ascended scattering layer indicate that these are very close to the resonant size for 12-kcy/sec sound. Because such organisms are capable of making prolonged vertical migrations, and are widespread geographically, they are very probably the major cause of stratified zones of scattering throughout the oceans of the world.

Migration of Chemotactic Bacteria Transverse to Flow in Response to a Benzoate Source Plume Created in a Saturated Sand-Packed Microcosm

NASA Astrophysics Data System (ADS)

Ford, R.; Boser, B.

2012-12-01

Bioremediation processes depend on contact between microbial populations and the groundwater contaminants that they biodegrade. Chemotaxis, the ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, can enhance the transport of bacteria toward contaminant sources that may not be readily accessible by advection and dispersion alone. A two-dimensional rectangular-shaped microcosm packed with quartz sand was used to quantify the effect of chemotaxis on the migration of bacteria within a saturated model aquifer system. Artificial groundwater was pumped through the microcosm at a rate of approximately 1 m/day. A plume of sodium benzoate was created by continuous injection into an upper port of the microcosm to generate a chemical gradient in the vertical direction transverse to flow. Chemotactic bacteria, Pseudomonas putida F1, or the nonchemotactic mutant, P. putida F1 CheA, were injected with a conservative tracer in a port several centimeters below the benzoate position. As the injectates traversed the one-meter length of the microcosm, samples were collected from a dozen effluent ports to determine vertical concentration distributions for the bacteria, benzoate and tracer. A moment analysis was implemented to estimate the center of mass, variance, and skewness of the concentration profiles. The transverse dispersion coefficient and the transverse dispersivity for chemotactic and nonchemotactic bacteria were also evaluated. Experiments performed with a continuous injection of bacteria showed that the center of mass for chemotactic bacteria was closer to the benzoate source on average than the nonchemotactic control (relative to the conservative tracer). These results demonstrated that chemotaxis can increase bacterial transport toward contaminants, potentially enhancing the effectiveness of in situ bioremediation. Experiments with 2 cm and 3 cm spacing between bacteria and benzoate injection locations were performed to explore the relationship between the exposure time of the bacteria to benzoate and the transverse migration of bacteria due to chemotaxis. Experimentally determined transport parameters were then used as input to a two-dimensional mathematical model for bacterial transport. Model results showed the shift in center of mass for chemotactic bacteria was greater for 2 cm and 3 cm spacing than for 4 cm spacing for a given chemotactic sensitivity coefficient value, which showed that an increase in the exposure time of the bacteria to the model contaminant benzoate increased the transverse migration of bacteria. Modeling was used to test the effects of changing the chemotactic sensitivity coefficient and the chemotaxis receptor constant at three different bacteria and benzoate separation distances: 2 cm, 3 cm, and 4 cm. Mathematical models from this work can be applied to future field-scale studies to select design parameters that maximize transverse migration of chemotactic bacteria.

Methanesulfonic acid (MSA) migration in polar ice: data synthesis and theory

NASA Astrophysics Data System (ADS)

Osman, Matthew; Das, Sarah B.; Marchal, Olivier; Evans, Matthew J.

2017-11-01

Methanesulfonic acid (MSA; CH3SO3H) in polar ice is a unique proxy of marine primary productivity, synoptic atmospheric transport, and regional sea-ice behavior. However, MSA can be mobile within the firn and ice matrix, a post-depositional process that is well known but poorly understood and documented, leading to uncertainties in the integrity of the MSA paleoclimatic signal. Here, we use a compilation of 22 ice core MSA records from Greenland and Antarctica and a model of soluble impurity transport in order to comprehensively investigate the vertical migration of MSA from summer layers, where MSA is originally deposited, to adjacent winter layers in polar ice. We find that the shallowest depth of MSA migration in our compilation varies over a wide range (˜ 2 to 400 m) and is positively correlated with snow accumulation rate and negatively correlated with ice concentration of Na+ (typically the most abundant marine cation). Although the considered soluble impurity transport model provides a useful mechanistic framework for studying MSA migration, it remains limited by inadequate constraints on key physico-chemical parameters - most notably, the diffusion coefficient of MSA in cold ice (DMS). We derive a simplified version of the model, which includes DMS as the sole parameter, in order to illuminate aspects of the migration process. Using this model, we show that the progressive phase alignment of MSA and Na+ concentration peaks observed along a high-resolution West Antarctic core is most consistent with 10-12 m2 s-1 < DMS < 10-11 m2 s-1, which is 1 order of magnitude greater than the DMS values previously estimated from laboratory studies. More generally, our data synthesis and model results suggest that (i) MSA migration may be fairly ubiquitous, particularly at coastal and (or) high-accumulation regions across Greenland and Antarctica; and (ii) can significantly change annual and multiyear MSA concentration averages. Thus, in most cases, caution should be exercised when interpreting polar ice core MSA records, although records that have undergone severe migration could still be useful for inferring decadal and lower-frequency climate variability.

Plume capture by a migrating ridge: Analog geodynamic experiments

NASA Astrophysics Data System (ADS)

Mendez, J. S.; Hall, P.

2010-12-01

Paleomagnetic data from the Hawaii-Emperor Seamount Chain (HESC) suggests that the Hawaiian hotspot moved rapidly (~40 mm/yr) between 81 - 47 Ma but has remained relatively stationary since that time. This implies that the iconic bend in the HESC may in fact reflect the transition from a period of rapid hotspot motion to a stationary state, rather than a change in motion of the Pacific plate. Tarduno et al. (2009) have suggested that this period of rapid hotspot motion might be the surface expression of a plume conduit returning to a largely vertical orientation after having been “captured” and tilted by a migrating mid-ocean ridge. We report on a series of analog fluid dynamic experiments designed to characterize the interaction between a migrating spreading center and a thermally buoyant mantle plume. Experiments were conducted in a clear acrylic tank (100 cm x 70 cm x 50 cm) filled with commercial grade high-fructose corn syrup. Plate-driven flow is modeled by dragging two sheets of Mylar film (driven by independent DC motors) in opposite directions over the surface of the fluid. Ridge migration is achieved by moving the point at which the mylar sheets diverge using a separate motor drive. Buoyant plume flow is modeled using corn syrup introduced into the bottom of the tank from an external, heated, pressurized reservoir. Small (~2 mm diameter), neutrally buoyant Delrin spheres are mixed into reservoir of plume material to aid in visualization. Plate velocities and ridge migration rate are controlled and plume temperature monitored using LabView software. Experiments are recorded using digital video which is then analyzed using digital image analysis software to track the position and shape of the plume conduit throughout the course of the experiment. The intersection of the plume conduit with the surface of the fluid is taken as an analog for the locus of hotspot volcanism and tracked as a function of time to obtain a hotspot migration rate. Experiments are scaled to the Earth's mantle through a combination of a Peclet number and a plume buoyancy number. A range of spreading rates, ridge migration rates, and plume excess temperatures representative of the Earth are considered.

Experimental analysis on viscoelasticity-induced migration of RBCs using digital holographic microscopy

NASA Astrophysics Data System (ADS)

Go, Taesik; Byeon, Hyeokjun; Lee, Sang Joon

2016-11-01

Migration of particles in viscoelastic fluids has recently received large attention, because the generated elastic forces in viscoelastic fluids give rise to a simple focusing pattern over a wide range of flow rates. In this study, the vertical focusing and alignment of rigid spherical particles, normal and hardened RBCs in a viscoelastic fluid were experimentally investigated by employing a digital in-line holographic microscopy (DIHM). By the elastic forces, the three different particles are pushed away from the walls and concentrated in the midplane of the rectangular microchannel. Furthermore, most of both RBCs maintain face-on orientation in the microchannel. The effects of deformability of RBC on the viscoelasticity-induced migration and orientation in the channel were also examined. In contrary to non-deformable particles, normal RBCs are dispersed as flow rate increases. In the region near side wall of the microchannel, normal RBCs have edge-on orientation with a large angle of inclination, compared to hardened RBCs. These findings have a strong potential in the design of microfluidic devices for deformability-based separation of cells in viscoelastic fluid flows and label-free diagnoses of certain hematological diseases. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2008-0061991).

Efficient anisotropic quasi-P wavefield extrapolation using an isotropic low-rank approximation

NASA Astrophysics Data System (ADS)

Zhang, Zhen-dong; Liu, Yike; Alkhalifah, Tariq; Wu, Zedong

2018-04-01

The computational cost of quasi-P wave extrapolation depends on the complexity of the medium, and specifically the anisotropy. Our effective-model method splits the anisotropic dispersion relation into an isotropic background and a correction factor to handle this dependency. The correction term depends on the slope (measured using the gradient) of current wavefields and the anisotropy. As a result, the computational cost is independent of the nature of anisotropy, which makes the extrapolation efficient. A dynamic implementation of this approach decomposes the original pseudo-differential operator into a Laplacian, handled using the low-rank approximation of the spectral operator, plus an angular dependent correction factor applied in the space domain to correct for anisotropy. We analyse the role played by the correction factor and propose a new spherical decomposition of the dispersion relation. The proposed method provides accurate wavefields in phase and more balanced amplitudes than a previous spherical decomposition. Also, it is free of SV-wave artefacts. Applications to a simple homogeneous transverse isotropic medium with a vertical symmetry axis (VTI) and a modified Hess VTI model demonstrate the effectiveness of the approach. The Reverse Time Migration applied to a modified BP VTI model reveals that the anisotropic migration using the proposed modelling engine performs better than an isotropic migration.

Numerical Simulation of Potential Groundwater Contaminant Pathways from Hydraulically Fractured Oil Shale in the Nevada Basin and Range Province

NASA Astrophysics Data System (ADS)

Rybarski, S.; Pohll, G.; Pohlmann, K.; Plume, R.

2014-12-01

In recent years, hydraulic fracturing (fracking) has become an increasingly popular method for extraction of oil and natural gas from tight formations. Concerns have been raised over a number of environmental risks associated with fracking, including contamination of groundwater by fracking fluids, upwelling of deep subsurface brines, and methane migration. Given the potentially long time scale for contaminant transport associated with hydraulic fracturing, numerical modeling remains the best practice for risk assessment. Oil shale in the Humboldt basin of northeastern Nevada has now become a target for hydraulic fracturing operations. Analysis of regional and shallow groundwater flow is used to assess several potential migration pathways specific to the geology and hydrogeology of this basin. The model domain in all simulations is defined by the geologic structure of the basin as determined by deep oil and gas well bores and formation outcrops. Vertical transport of gaseous methane along a density gradient is simulated in TOUGH2, while fluid transport along faults and/or hydraulic fractures and lateral flow through more permeable units adjacent to the targeted shale are modeled in FEFLOW. Sensitivity analysis considers basin, fault, and hydraulic fracturing parameters, and results highlight key processes that control fracking fluid and methane migration and time scales under which it might occur.

KSC-98pc411

NASA Image and Video Library

1998-03-11

KENNEDY SPACE CENTER, FLA. -- Swordtail fish (Xiphophorus helleri), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, are shown in their holding tanks in the Operations and Checkout Building. The fish will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D

KSC-98pc409

NASA Image and Video Library

1998-03-11

KENNEDY SPACE CENTER, FLA. -- A water snail (Biomphalaria glabrata), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, is held up for inspection in the Operations and Checkout Building. The snails will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, includes Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D

KSC-98pc412

NASA Image and Video Library

1998-03-11

KENNEDY SPACE CENTER, FLA. -- Swordtail fish (Xiphophorus helleri), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, are shown in their holding tank in the Operations and Checkout Building. The fish will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D

KSC-98pc408

NASA Image and Video Library

1998-03-11

KENNEDY SPACE CENTER, FLA. -- Swordtail fish (Xiphophorus helleri), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, are shown in their holding tank in the Operations and Checkout Building. The fish will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D.

Swordtail fish fly on STS-90 as part of Neurolab

NASA Technical Reports Server (NTRS)

1998-01-01

Swordtail fish (Xiphophorus helleri), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, are shown in their holding tank in the Operations and Checkout Building. The fish will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D.

Swordtail fish fly on STS-90 as part of Neurolab

NASA Technical Reports Server (NTRS)

1998-01-01

Swordtail fish (Xiphophorus helleri), like those that are part of the Neurolab payload on Space Shuttle Mission STS-90, are shown in their holding tanks in the Operations and Checkout Building. The fish will fly in the Closed Equilibrated Biological Aquatic System (CEBAS) Minimodule, a middeck locker-sized fresh water habitat, designed to allow the controlled incubation of aquatic species in a self-stabilizing, artifical ecosystem for up to three weeks under space conditions. Investigations during the Neurolab mission will focus on the effects of microgravity on the nervous system. The crew of STS-90, slated for launch April 16 at 2:19 p.m. EDT, include Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Richard Linnehan, D.V.M., Dafydd (Dave) Williams, M.D., and Kathryn (Kay) Hire, and Payload Specialists Jay Buckey, M.D., and James Pawelczyk, Ph.D.

Stratigraphic architecture of hydromagmatic volcanoes that have undergone vent migration: a review of Korean case studies

NASA Astrophysics Data System (ADS)

Sohn, Y.

2011-12-01

Recent studies show that the architecture of hydromagmatic volcanoes is far more complex than formerly expected. A number of external factors, such as paleohydrology and tectonics, in addition to magmatic processes are thought to play a role in controlling the overall characteristics and architecture of these volcanoes. One of the main consequences of these controls is the migration of the active vent during eruption. Case studies of hydromagmatic volcanoes in Korea show that those volcanoes that have undergone vent migration are characterized by superposition or juxtaposition of multiple rim deposits of partial tuff rings and/or tuff cones that have contrasting lithofacies characteristics, bed attitudes, and paleoflow directions. Various causes of vent migration are inferred from these volcanoes. Large-scale collapse of fragile substrate is interpreted to have caused vent migration in the Early Pleistocene volcanoes of Jeju Island, which were built upon still unconsolidated continental shelf sediments. Late Pleistocene to Holocene volcanoes, which were built upon a stack of rigid, shield-forming lava flows, lack features due to large-scale substrate collapse and have generally simple and circular morphologies either of a tuff ring or of a tuff cone. However, ~600 m shift of the eruptive center is inferred from one of these volcanoes (Ilchulbong tuff cone). The vent migration in this volcano is interpreted to have occurred because the eruption was sourced by multiple magma batches with significant eruptive pauses in between. The Yangpori diatreme in a Miocene terrestrial half-graben basin in SE Korea is interpreted to be a subsurface equivalent of a hydromagmatic volcano that has undergone vent migration. The vent migration here is inferred to have had both vertical and lateral components and have been caused by an abrupt tectonic activity near the basin margin. In all these cases, rimbeds or diatreme fills derived from different source vents are bounded by either prominent or subtle, commonly laterally extensive truncation surfaces or stratigraphic discontinuities. Careful documentation of these surfaces and discontinuities thus appears vital to proper interpretation of eruption history, morphologic evolution, and even deep-seated magmatic processes of a hydromagmatic volcano. In this respect, the technique known as 'allostratigraphy' appears useful in mapping, correlation, and interpretation of many hydrovolcanic edifices and sequences.

3D Tensorial Elastodynamics for Isotropic Media on Vertically Deformed Meshes

NASA Astrophysics Data System (ADS)

Shragge, J. C.

2017-12-01

Solutions of the 3D elastodynamic wave equation are sometimes required in industrial and academic applications of elastic reverse-time migration (E-RTM) and full waveform inversion (E-FWI) that involve vertically deformed meshes. Examples include incorporating irregular free-surface topography and handling internal boundaries (e.g., water bottom) directly into the computational meshes. In 3D E-RTM and E-FWI applications, the number of forward modeling simulations can number in the tens of thousands (per iteration), which necessitates the development of stable, accurate and efficient 3D elastodynamics solvers. For topographic scenarios, most finite-difference solution approaches use a change-of-variable strategy that has a number of associated computational challenges, including difficulties in handling of the free-surface boundary condition. In this study, I follow a tensorial approach and use a generalized family of analytic transforms to develop a set of analytic equations for 3D elastodynamics that directly incorporates vertical grid deformations. Importantly, this analytic approach allows for the specification of an analytic free-surface boundary condition appropriate for vertically deformed meshes. These equations are both straightforward and efficient to solve using a velocity-stress formulation with finite-difference (MFD) operators implemented on a fully staggered grid. Moreover, I demonstrate that the use of mimetic finite difference (MFD) methods allows stable, accurate, and efficient numerical solutions to be simulated for typical topographic scenarios. Examples demonstrate that high-quality elastic wavefields can be generated for topographic surfaces exhibiting significant topographic relief.

Novel techniques and insights into the deployment of pop-up satellite archival tags on a small-bodied deep-water chondrichthyan

NASA Astrophysics Data System (ADS)

Shipley, Oliver N.; Howey, Lucy A.; Tolentino, Emily R.; Jordan, Lance K. B.; Brooks, Edward J.

2017-01-01

Acquiring movement data for small-bodied, deep-water chondrichthyans is challenged by extreme effects of capture and handling stress, and post-release predation, however, it is urgently required to examine important fisheries interactions and assess the ecological role of these species within deep-water food webs. Here we suggest a novel release-cage mechanism to deploy pop-up satellite archival tags, as well as present vertical habitat data for a data-deficient, small-bodied, deep-water bycatch species, the Cuban dogfish (Squalus cubensis). Data were gathered from seven of eight High Rate X-Tags deployed on mature Cuban dogfish in the Exuma Sound, The Bahamas. Recovery periods appeared variable between individuals and are likely driven by capture-and-handling stress and tag burden. Application of the cross-correlation function to time-series depth and temperature data indicated three of the seven individuals suffered mortality through predation, which occurred during daytime, and suggests Cuban dogfish may constitute a proportion of deep-water apex predator diet in the Exuma Sound. Two animals were successfully released via a novel release-cage mechanism and displayed either no, or rapid (<15 mins) vertically stationary recovery periods and were not consumed by predators; data for these individuals were recorded for the entire deployment duration (14 days). Vertical habitat data suggests Cuban dogfish are diel-vertical migrators, similar to other deep-water taxa, and exhibit a relatively broad temperature and depth range, which may be driven by preference for specific bathymetric structures. These techniques provide an important first step into acquiring and presenting vertical habitat data for small-bodied, deep-water chondrichthyans, which can be directly applied to fisheries and ecosystem-based management approaches.

Transport and retention of vertically migrating adult mysid and decapod shrimp in the tidal front on Georges Bank

USGS Publications Warehouse

Lough, R. Gregory; Aretxabaleta, Alfredo L.

2014-01-01

Vertical profiles of the adult epibenthic shrimp Neomysis americana and Crangon septemspinosus obtained during June 1985 were used to simulate possible rates of ascent from bottom (40 to 50 m) to near surface at night and return by day, and the consequence of these rates on their horizontal distribution. Numerical particles were released at the sampling site using archived model current fields with specified vertical rates (from no swim behavior to 20 mm s(-1)) and tracked for up to 30 d. The best match between observed and modeled vertical profiles was with a vertical swimming speed of 10 mm s(-1) for N. americana and 2 mm s(-1) for C. septemspinosus. Whereas N. americana rapidly swims towards the surface at dusk and descends to bottom by dawn, C. septemspinosus tends to only swim up to the middle of the water column at night. After 16 d, the simulation with 10 mm s(-1) swim speed showed most particles were concentrated in an area centered around the 60 m isobath, where the tidal front was located. At 2 mm s(-1) swim speed particles were concentrated more shoalward onto the western end of Georges Bank. N. americana are expected to be more closely associated with the tidal front, since they spend more time near the front surface convergence, but are more likely to be transported off the bank due to the south-westward-flowing surface tidal jet, whereas C. septemspinosus would be retained primarily on the bank, since they are found deeper in the water column during both day and night.

RADIALLY MAGNETIZED PROTOPLANETARY DISK: VERTICAL PROFILE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russo, Matthew; Thompson, Christopher

2015-11-10

This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiencesmore » the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field B{sub r} ∼ (10{sup −4}–10{sup −2})(r/ AU){sup −2} G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ∼1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10{sup −8} M{sub ⊙} yr{sup −1} are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper.« less

Altitudinal patterns in breeding bird species richness and density in relation to climate, habitat heterogeneity, and migration influence in a temperate montane forest (South Korea).

PubMed

Kim, Jin-Yong; Lee, Sanghun; Shin, Man-Seok; Lee, Chang-Hoon; Seo, Changwan; Eo, Soo Hyung

2018-01-01

Altitudinal patterns in the population ecology of mountain bird species are useful for predicting species occurrence and behavior. Numerous hypotheses about the complex interactions among environmental factors have been proposed; however, these still remain controversial. This study aimed to identify the altitudinal patterns in breeding bird species richness or density and to test the hypotheses that climate, habitat heterogeneity (horizontal and vertical), and heterospecific attraction in a temperate forest, South Korea. We conducted a field survey of 142 plots at altitudes between 200 and 1,400 m a.s.l in the breeding season. A total of 2,771 individuals from 53 breeding bird species were recorded. Altitudinal patterns of species richness and density showed a hump-shaped pattern, indicating that the highest richness and density could be observed at moderate altitudes. Models constructed with 13 combinations of six variables demonstrated that species richness was positively correlated with vertical and horizontal habitat heterogeneity. Density was positively correlated with vertical, but not horizontal habitat heterogeneity, and negatively correlated with migratory bird ratio. No significant relationships were found between spring temperature and species richness or density. Therefore, the observed patterns in species richness support the hypothesis that habitat heterogeneity, rather than climate, is the main driver of species richness. Also, neither habitat heterogeneity nor climate hypotheses fully explains the observed patterns in density. However, vertical habitat heterogeneity does likely help explain observed patterns in density. The heterospecific attraction hypothesis did not apply to the distribution of birds along the altitudinal gradient. Appropriate management of vertical habitat heterogeneity, such as vegetation cover, should be maintained for the conservation of bird diversity in this area.

Diel Vertical Dynamics of Gelatinous Zooplankton (Cnidaria, Ctenophora and Thaliacea) in a Subtropical Stratified Ecosystem (South Brazilian Bight)

PubMed Central

Nogueira Júnior, Miodeli; Brandini, Frederico Pereira; Codina, Juan Carlos Ugaz

2015-01-01

The diel vertical dynamics of gelatinous zooplankton in physically stratified conditions over the 100-m isobath (~110 km offshore) in the South Brazilian Bight (26°45’S; 47°33’W) and the relationship to hydrography and food availability were analyzed by sampling every six hours over two consecutive days. Zooplankton samples were taken in three depth strata, following the vertical structure of the water column, with cold waters between 17 and 13.1°C, influenced by the South Atlantic Central Water (SACW) in the lower layer (>70 m); warm (>20°C) Tropical Water in the upper 40 m; and an intermediate thermocline with a deep chlorophyll-a maximum layer (0.3–0.6 mg m-3). Two distinct general patterns were observed, emphasizing the role of (i) physical and (ii) biological processes: (i) a strong influence of the vertical stratification, with most zooplankton absent or little abundant in the lower layer. The influence of the cold SACW on the bottom layer apparently restricted the vertical occupation of most species, which typically inhabit epipelagic warm waters. Even among migratory species, only a few (Aglaura hemistoma, Abylopsis tetragona eudoxids, Beroe sp., Thalia democratica, Salpa fusiformis) crossed the thermocline and reached the bottom layer. (ii) A general tendency of partial migrations, with variable intensity depending on the different species and developmental stages; populations tended to be more widely distributed through the water column during daylight, and to become more aggregated in the upper layer during the night, which can be explained based on the idea of the “hunger-satiation hypothesis”, maximizing feeding and minimizing the chances of being predated. PMID:26637179

Diel Vertical Dynamics of Gelatinous Zooplankton (Cnidaria, Ctenophora and Thaliacea) in a Subtropical Stratified Ecosystem (South Brazilian Bight).

PubMed

Nogueira Júnior, Miodeli; Brandini, Frederico Pereira; Codina, Juan Carlos Ugaz

2015-01-01

The diel vertical dynamics of gelatinous zooplankton in physically stratified conditions over the 100-m isobath (~110 km offshore) in the South Brazilian Bight (26°45'S; 47°33'W) and the relationship to hydrography and food availability were analyzed by sampling every six hours over two consecutive days. Zooplankton samples were taken in three depth strata, following the vertical structure of the water column, with cold waters between 17 and 13.1°C, influenced by the South Atlantic Central Water (SACW) in the lower layer (>70 m); warm (>20°C) Tropical Water in the upper 40 m; and an intermediate thermocline with a deep chlorophyll-a maximum layer (0.3-0.6 mg m-3). Two distinct general patterns were observed, emphasizing the role of (i) physical and (ii) biological processes: (i) a strong influence of the vertical stratification, with most zooplankton absent or little abundant in the lower layer. The influence of the cold SACW on the bottom layer apparently restricted the vertical occupation of most species, which typically inhabit epipelagic warm waters. Even among migratory species, only a few (Aglaura hemistoma, Abylopsis tetragona eudoxids, Beroe sp., Thalia democratica, Salpa fusiformis) crossed the thermocline and reached the bottom layer. (ii) A general tendency of partial migrations, with variable intensity depending on the different species and developmental stages; populations tended to be more widely distributed through the water column during daylight, and to become more aggregated in the upper layer during the night, which can be explained based on the idea of the "hunger-satiation hypothesis", maximizing feeding and minimizing the chances of being predated.

Stirring Up the Biological Pump: Vertical Mixing and Carbon Export in the Southern Ocean

NASA Astrophysics Data System (ADS)

Stukel, Michael R.; Ducklow, Hugh W.

2017-09-01

The biological carbon pump (BCP) transports organic carbon from the surface to the ocean's interior via sinking particles, vertically migrating organisms, and passive transport of organic matter by advection and diffusion. While many studies have quantified sinking particles, the magnitude of passive transport remains poorly constrained. In the Southern Ocean weak thermal stratification, strong vertical gradients in particulate organic matter, and weak vertical nitrate gradients suggest that passive transport from the euphotic zone may be particularly important. We compile data from seasonal time series at a coastal site near Palmer Station, annual regional cruises in the Western Antarctic Peninsula (WAP), cruises throughout the broader Southern Ocean, and SOCCOM (Southern Ocean Carbon and Climate Observations and Modeling) autonomous profiling floats to estimate spatial and temporal patterns in vertical gradients of nitrate, particulate nitrogen (PN), and dissolved organic carbon. Under a steady state approximation, the ratio of ∂PN/∂z to ∂NO3-/∂z suggests that passive transport of PN may be responsible for removing 46% (37%-58%) of the nitrate introduced into the surface ocean of the WAP (with dissolved organic matter contributing an additional 3-6%) and for 23% (19%-28%) of the BCP in the broader Southern Ocean. A simple model parameterized with in situ nitrate, PN, and primary production data suggested that passive transport was responsible for 54% of the magnitude of the BCP in the WAP. Our results highlight the potential importance of passive transport (by advection and diffusion) of organic matter in the Southern Ocean but should only be considered indicative of high passive transport (rather than conclusive evidence) due to our steady state assumptions.

The vertical structure of gaseous galaxy discs in cold dark matter haloes

NASA Astrophysics Data System (ADS)

Benítez-Llambay, Alejandro; Navarro, Julio F.; Frenk, Carlos S.; Ludlow, Aaron D.

2018-01-01

We study the vertical structure of polytropic centrifugally supported gaseous discs embedded in cold dark matter (CDM) haloes. At fixed radius, R, the shape of the vertical density profile depends weakly on whether the disc is self-gravitating (SG) or non-self-gravitating (NSG). The disc 'characteristic' thickness, zH, set by the midplane sound speed and circular velocity, zNSG = (cs/Vc)R, in the NSG case, and by the sound speed and surface density, z_SG = c_s^2/GΣ, in SG discs, is smaller than zSG and zNSG. SG discs are typically Toomre unstable, NSG discs are stable. Exponential discs in CDM haloes with roughly flat circular velocity curves 'flare' outwards. Flares in mono abundance or coeval populations in galaxies like the Milky Way are thus not necessarily due to radial migration. For the polytropic equation of state of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulations, discs that match observational constraints are NSG for Md < 3 × 109 M⊙ and SG at higher masses, if fully gaseous. We test these analytic results using a set of idealized smoothed particle hydrodynamic simulations and find excellent agreement. Our results clarify the role of the gravitational softening on the thickness of simulated discs, and on the onset of radial instabilities. EAGLE low-mass discs are NSG so the softening plays no role in their vertical structure. High-mass discs are expected to be SG and unstable, and may be artificially thickened and stabilized unless gravity is well resolved. Simulations with spatial resolution high enough to not compromise the vertical structure of a disc also resolve the onset of their instabilities, but the converse is not true.

The GALAH survey: properties of the Galactic disc(s) in the solar neighbourhood

NASA Astrophysics Data System (ADS)

Duong, L.; Freeman, K. C.; Asplund, M.; Casagrande, L.; Buder, S.; Lind, K.; Ness, M.; Bland-Hawthorn, J.; De Silva, G. M.; D'Orazi, V.; Kos, J.; Lewis, G. F.; Lin, J.; Martell, S. L.; Schlesinger, K.; Sharma, S.; Simpson, J. D.; Zucker, D. B.; Zwitter, T.; Anguiano, B.; Da Costa, G. S.; Hyde, E.; Horner, J.; Kafle, P. R.; Nataf, D. M.; Reid, W.; Stello, D.; Ting, Y.-S.; Wyse, R. F. G.

2018-06-01

Using data from the GALAH pilot survey, we determine properties of the Galactic thin and thick discs near the solar neighbourhood. The data cover a small range of Galactocentric radius (7.9 ≲ R_GC ≲ 9.5 kpc), but extend up to 4 kpc in height from the Galactic plane, and several kpc in the direction of Galactic anti-rotation (at longitude 260° ≤ ℓ ≤ 280°). This allows us to reliably measure the vertical density and abundance profiles of the chemically and kinematically defined `thick' and `thin' discs of the Galaxy. The thin disc (low-α population) exhibits a steep negative vertical metallicity gradient, at d[M/H]/dz = -0.18 ± 0.01 dex kpc-1, which is broadly consistent with previous studies. In contrast, its vertical α-abundance profile is almost flat, with a gradient of d[α/M]/dz = 0.008 ± 0.002 dex kpc-1. The steep vertical metallicity gradient of the low-α population is in agreement with models where radial migration has a major role in the evolution of the thin disc. The thick disc (high-α population) has a weaker vertical metallicity gradient d[M/H]/dz = -0.058 ± 0.003 dex kpc-1. The α-abundance of the thick disc is nearly constant with height, d[α/M]/dz = 0.007 ± 0.002 dex kpc-1. The negative gradient in metallicity and the small gradient in [α/M] indicate that the high-α population experienced a settling phase, but also formed prior to the onset of major Type Ia supernova enrichment. We explore the implications of the distinct α-enrichments and narrow [α/M] range of the sub-populations in the context of thick disc formation.

A new geodynamic model related to seismicity beneath the southeastern margin of the Tibetan Plateau revealed by regional tomography

NASA Astrophysics Data System (ADS)

Hua, Yujin; Zhang, Shuangxi; Li, Mengkui; Wu, Tengfei; Qin, Weibing; Wang, Fang; Zhang, Bo

2018-05-01

The southeastern margin of the Tibetan Plateau (SETP) presents the highest level of seismicity in mainland China. To understand the seismicity in this region, a new seismic experiment is carried out based on the tomographic inversion of P- and S-wave arrival times from the regional earthquakes recorded by 49 seismic stations in Yunnan Province of Southwest China. In this study, we reduce the extreme disproportionality of the data distribution using an events-combination method, and we use arrival times to construct the reference velocity model. Checkerboard tests and odd/even data tests are carried out to assess the reliability of the inversion results. The reliable P-wave velocity model reveals two low-velocity anomaly zones (LVAZs) bounded by major strike-slip faults. Almost all the large earthquakes in this region occurred in the two LVAZs and the trend of the two LVAZs is consistent with a GPS velocity field based on the Eurasia-fixed reference frame. We propose that the two LVAZs are material migration passageways in the SETP. In the vertical direction, the mechanically weak crustal materials are sliding southward with the rigid block, while the underlying mantle materials continue to be compressed by the collision. This vertical model is broadly consistent with the seismic anisotropy in the crust and lithospheric mantle from shear-wave splitting. The new regional geodynamic model gives a reasonable interpretation of the seismicity of the SETP, and we suggest that the material migration in the passageway zones plays an important role in the tectonic evolution of the SETP.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, Michael

Geomechanics Technologies has completed a detailed characterization study of the Wilmington Graben offshore Southern California area for large-scale CO₂ storage. This effort has included: an evaluation of existing wells in both State and Federal waters, field acquisition of about 175 km (109 mi) of new seismic data, new well drilling, development of integrated 3D geologic, geomechanics, and fluid flow models for the area. The geologic analysis indicates that more than 796 MMt of storage capacity is available within the Pliocene and Miocene formations in the Graben for midrange geologic estimates (P50). Geomechanical analyses indicate that injection can be conducted withoutmore » significant risk for surface deformation, induced stresses or fault activation. Numerical analysis of fluid migration indicates that injection into the Pliocene Formation at depths of 1525 m (5000 ft) would lead to undesirable vertical migration of the CO₂ plume. Recent well drilling however, indicates that deeper sand is present at depths exceeding 2135 m (7000 ft), which could be viable for large volume storage. For vertical containment, injection would need to be limited to about 250,000 metric tons per year per well, would need to be placed at depths greater than 7000ft, and would need to be placed in new wells located at least 1 mile from any existing offset wells. As a practical matter, this would likely limit storage operations in the Wilmington Graben to about 1 million tons per year or less. A quantitative risk analysis for the Wilmington Graben indicate that such large scale CO₂ storage in the area would represent higher risk than other similar size projects in the US and overseas.« less

Sardine (Sardina pilchardus) larval dispersal in the Iberian upwelling system, using coupled biophysical techniques

NASA Astrophysics Data System (ADS)

Santos, A. M. P.; Nieblas, A.-E.; Verley, P.; Teles-Machado, A.; Bonhommeau, S.; Lett, C.; Garrido, S.; Peliz, A.

2018-03-01

The European sardine (Sardina pilchardus) is the most important small pelagic fishery of the Western Iberia Upwelling Ecosystem (WIUE). Recently, recruitment of this species has declined due to changing environmental conditions. Furthermore, controversies exist regarding its population structure with barriers thought to exist between the Atlantic-Iberian Peninsula, Northern Africa, and the Mediterranean. Few studies have investigated the transport and dispersal of sardine eggs and larvae off Iberia and the subsequent impact on larval recruitment variability. Here, we examine these issues using a Regional Ocean Modeling System climatology (1989-2008) coupled to the Lagrangian transport model, Ichthyop. Using biological parameters from the literature, we conduct simulations that investigate the effects of spawning patchiness, diel vertical migration behaviors, and egg buoyancy on the transport and recruitment of virtual sardine ichthyoplankton on the continental shelf. We find that release area, release depth, and month of release all significantly affect recruitment. Patchiness has no effect and diel vertical migration causes slightly lower recruitment. Egg buoyancy effects are significant and act similarly to depth of release. As with other studies, we find that recruitment peaks vary by latitude, explained here by the seasonal variability of offshore transport. We find weak, continuous alongshore transport between release areas, though a large proportion of simulated ichthyoplankton transport north to the Cantabrian coast (up to 27%). We also show low level transport into Morocco (up to 1%) and the Mediterranean (up to 8%). The high proportion of local retention and low but consistent alongshore transport supports the idea of a series of metapopulations along this coast.

Sensitivity to ocean acidification parallels natural pCO2 gradients experienced by Arctic copepods under winter sea ice

PubMed Central

Lewis, Ceri N.; Brown, Kristina A.; Edwards, Laura A.; Cooper, Glenn; Findlay, Helen S.

2013-01-01

The Arctic Ocean already experiences areas of low pH and high CO2, and it is expected to be most rapidly affected by future ocean acidification (OA). Copepods comprise the dominant Arctic zooplankton; hence, their responses to OA have important implications for Arctic ecosystems, yet there is little data on their current under-ice winter ecology on which to base future monitoring or make predictions about climate-induced change. Here, we report results from Arctic under-ice investigations of copepod natural distributions associated with late-winter carbonate chemistry environmental data and their response to manipulated pCO2 conditions (OA exposures). Our data reveal that species and life stage sensitivities to manipulated OA conditions were correlated with their vertical migration behavior and with their natural exposures to different pCO2 ranges. Vertically migrating adult Calanus spp. crossed a pCO2 range of >140 μatm daily and showed only minor responses to manipulated high CO2. Oithona similis, which remained in the surface waters and experienced a pCO2 range of <75 μatm, showed significantly reduced adult and nauplii survival in high CO2 experiments. These results support the relatively untested hypothesis that the natural range of pCO2 experienced by an organism determines its sensitivity to future OA and highlight that the globally important copepod species, Oithona spp., may be more sensitive to future high pCO2 conditions compared with the more widely studied larger copepods. PMID:24297880

Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits' expression

NASA Astrophysics Data System (ADS)

Pacheco, Aldo S.; Uribe, Roberto A.; Thiel, Martin; Oliva, Marcelo E.; Riascos, Jose M.

2013-03-01

Post-larval dispersal along the sediment-water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits "small size, swimming, hard exoskeleton, free living and surface position" were associated to water column and bedload dispersal. This study highlights the importance of (i) the water-sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.

Use of an Autonomous Surface Vehicle reveals small-scale diel vertical migrations of zooplankton and susceptibility to light pollution under low solar irradiance.

PubMed

Ludvigsen, Martin; Berge, Jørgen; Geoffroy, Maxime; Cohen, Jonathan H; De La Torre, Pedro R; Nornes, Stein M; Singh, Hanumant; Sørensen, Asgeir J; Daase, Malin; Johnsen, Geir

2018-01-01

Light is a major cue for nearly all life on Earth. However, most of our knowledge concerning the importance of light is based on organisms' response to light during daytime, including the dusk and dawn phase. When it is dark, light is most often considered as pollution, with increasing appreciation of its negative ecological effects. Using an Autonomous Surface Vehicle fitted with a hyperspectral irradiance sensor and an acoustic profiler, we detected and quantified the behavior of zooplankton in an unpolluted light environment in the high Arctic polar night and compared the results with that from a light-polluted environment close to our research vessels. First, in environments free of light pollution, the zooplankton community is intimately connected to the ambient light regime and performs synchronized diel vertical migrations in the upper 30 m despite the sun never rising above the horizon. Second, the vast majority of the pelagic community exhibits a strong light-escape response in the presence of artificial light, observed down to 100 m. We conclude that artificial light from traditional sampling platforms affects the zooplankton community to a degree where it is impossible to examine its abundance and natural rhythms within the upper 100 m. This study underscores the need to adjust sampling platforms, particularly in dim-light conditions, to capture relevant physical and biological data for ecological studies. It also highlights a previously unchartered susceptibility to light pollution in a region destined to see significant changes in light climate due to a reduced ice cover and an increased anthropogenic activity.

Shallow Aquifer Vulnerability From Subsurface Fluid Injection at a Proposed Shale Gas Hydraulic Fracturing Site

NASA Astrophysics Data System (ADS)

Wilson, M. P.; Worrall, F.; Davies, R. J.; Hart, A.

2017-11-01

Groundwater flow resulting from a proposed hydraulic fracturing (fracking) operation was numerically modeled using 91 scenarios. Scenarios were chosen to be a combination of hydrogeological factors that a priori would control the long-term migration of fracking fluids to the shallow subsurface. These factors were induced fracture extent, cross-basin groundwater flow, deep low hydraulic conductivity strata, deep high hydraulic conductivity strata, fault hydraulic conductivity, and overpressure. The study considered the Bowland Basin, northwest England, with fracking of the Bowland Shale at ˜2,000 m depth and the shallow aquifer being the Sherwood Sandstone at ˜300-500 m depth. Of the 91 scenarios, 73 scenarios resulted in tracked particles not reaching the shallow aquifer within 10,000 years and 18 resulted in travel times less than 10,000 years. Four factors proved to have a statistically significant impact on reducing travel time to the aquifer: increased induced fracture extent, absence of deep high hydraulic conductivity strata, relatively low fault hydraulic conductivity, and magnitude of overpressure. Modeling suggests that high hydraulic conductivity formations can be more effective barriers to vertical flow than low hydraulic conductivity formations. Furthermore, low hydraulic conductivity faults can result in subsurface pressure compartmentalization, reducing horizontal groundwater flow, and encouraging vertical fluid migration. The modeled worst-case scenario, using unlikely geology and induced fracture lengths, maximum values for strata hydraulic conductivity and with conservative tracer behavior had a particle travel time of 130 years to the base of the shallow aquifer. This study has identified hydrogeological factors which lead to aquifer vulnerability from shale exploitation.

Seasonal cross-shelf distribution of major zooplankton taxa on the northern Gulf of Alaska shelf relative to water mass properties, species depth preferences and vertical migration behavior

NASA Astrophysics Data System (ADS)

Coyle, Kenneth O.; Pinchuk, Alexei I.

2005-01-01

The cross-shelf distribution of major zooplankton species was examined on the northern Gulf of Alaska (GOA) shelf during the production season for four years, between October 1997 and October 2001. The zooplankton community on the northern GOA shelf consisted of oceanic and neritic species of the North Pacific subarctic species complex. Cross-shelf distribution of the major zooplankton species was influenced by their depth preferences, vertical migration behavior, salinity-temperature preferences, and by cross-shelf water-mass distribution and movement. The neritic community, dominated by Pseudocalanus spp., Metridia pacifica and Calanus marshallae, had highest abundances on the inner shelf, in the Alaska Coastal Current, and in the adjacent fjords in late spring and early summer. The oceanic community, which contained primarily Neocalanus cristatus and Eucalanus bungii, was observed in the Alaskan Stream and adjacent waters near the shelf break. A mid-shelf transition zone contained a mixture of oceanic and neritic species. Prince William Sound (PWS) contained a unique species complex of large mesopelagic copepods, amphipods and shrimp. Neocalanus flemingeri and Oithona similis were abundant in all four regions during spring and early summer. The transition zone commonly crossed much of the shelf between the shelf break and the ACC, but satellite images and CTD data indicate that occasionally a narrow shelf-break front can form, in which case distinct zooplankton species groups are observed on either side of the front. Satellite data also revealed numerous large and small eddies, which probably contribute to cross-shelf mixing in the transition zone.

Eleven quick tips for architecting biomedical informatics workflows with cloud computing.

PubMed

Cole, Brian S; Moore, Jason H

2018-03-01

Cloud computing has revolutionized the development and operations of hardware and software across diverse technological arenas, yet academic biomedical research has lagged behind despite the numerous and weighty advantages that cloud computing offers. Biomedical researchers who embrace cloud computing can reap rewards in cost reduction, decreased development and maintenance workload, increased reproducibility, ease of sharing data and software, enhanced security, horizontal and vertical scalability, high availability, a thriving technology partner ecosystem, and much more. Despite these advantages that cloud-based workflows offer, the majority of scientific software developed in academia does not utilize cloud computing and must be migrated to the cloud by the user. In this article, we present 11 quick tips for architecting biomedical informatics workflows on compute clouds, distilling knowledge gained from experience developing, operating, maintaining, and distributing software and virtualized appliances on the world's largest cloud. Researchers who follow these tips stand to benefit immediately by migrating their workflows to cloud computing and embracing the paradigm of abstraction.

Model Simulation of Diurnal Vertical Migration Patterns of Different-Sized Colonies of Microcystis Employing a Particle Trajectory Approach.

PubMed

Chien, Yu Ching; Wu, Shian Chee; Chen, Wan Ching; Chou, Chih Chung

2013-04-01

Microcystis , a genus of potentially harmful cyanobacteria, is known to proliferate in stratified freshwaters due to its capability to change cell density and regulate buoyancy. In this study, a trajectory model was developed to simulate the cell density change and spatial distribution of Microcystis cells with nonuniform colony sizes. Simulations showed that larger colonies migrate to the near-surface water layer during the night to effectively capture irradiation and become heavy enough to sink during daytime. Smaller-sized colonies instead took a longer time to get to the surface. Simulation of the diurnally varying Microcystis population profile matched the observed pattern in the field when the radii of the multisized colonies were in a beta distribution. This modeling approach is able to take into account the history of cells by keeping track of their positions and properties, such as cell density and the sizes of colonies. It also serves as the basis for further developmental modeling of phytoplanktons that are forming colonies and changing buoyancy.

Eleven quick tips for architecting biomedical informatics workflows with cloud computing

PubMed Central

Moore, Jason H.

2018-01-01

Cloud computing has revolutionized the development and operations of hardware and software across diverse technological arenas, yet academic biomedical research has lagged behind despite the numerous and weighty advantages that cloud computing offers. Biomedical researchers who embrace cloud computing can reap rewards in cost reduction, decreased development and maintenance workload, increased reproducibility, ease of sharing data and software, enhanced security, horizontal and vertical scalability, high availability, a thriving technology partner ecosystem, and much more. Despite these advantages that cloud-based workflows offer, the majority of scientific software developed in academia does not utilize cloud computing and must be migrated to the cloud by the user. In this article, we present 11 quick tips for architecting biomedical informatics workflows on compute clouds, distilling knowledge gained from experience developing, operating, maintaining, and distributing software and virtualized appliances on the world’s largest cloud. Researchers who follow these tips stand to benefit immediately by migrating their workflows to cloud computing and embracing the paradigm of abstraction. PMID:29596416

Space Radar Image of Mississippi Delta

NASA Image and Video Library

1999-04-15

This is a radar image of the Mississippi River Delta where the river enters into the Gulf of Mexico along the coast of Louisiana. This multi-frequency image demonstrates the capability of the radar to distinguish different types of wetlands surfaces in river deltas. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 2, 1995. The image is centered on latitude 29.3 degrees North latitude and 89.28 degrees West longitude. The area shown is approximately 63 kilometers by 43 kilometers (39 miles by 26 miles). North is towards the upper right of the image. As the river enters the Gulf of Mexico, it loses energy and dumps its load of sediment that it has carried on its journey through the mid-continent. This pile of sediment, or mud, accumulates over the years building up the delta front. As one part of the delta becomes clogged with sediment, the delta front will migrate in search of new areas to grow. The area shown on this image is the currently active delta front of the Mississippi. The migratory nature of the delta forms natural traps for oil and the numerous bright spots along the outside of the delta are drilling platforms. Most of the land in the image consists of mud flats and marsh lands. There is little human settlement in this area due to the instability of the sediments. The main shipping channel of the Mississippi River is the broad red stripe running northwest to southeast down the left side of the image. The bright spots within the channel are ships. The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vertically received; blue is X-band vertically transmitted, vertically received. http://photojournal.jpl.nasa.gov/catalog/PIA01784

Lateral Erosion Encourages Vertical Incision in a Bimodal Alluvial River

NASA Astrophysics Data System (ADS)

Gran, K. B.

2015-12-01

Sand can have a strong impact on gravel transport, increasing gravel transport rates by orders of magnitude as sand content increases. Recent experimental work by others indicates that adding sand to an armored bed can even cause armor to break-up and mobilize. These two elements together help explain observations from a bimodal sand and gravel-bedded river, where lateral migration into sand-rich alluvium breaks up the armor layer, encouraging further incision into the bed. Detailed bedload measurements were coupled with surface and subsurface grain size analyses and cross-sectional surveys in a seasonally-incised channel carved into the upper alluvial fan of the Pasig-Potrero River at Mount Pinatubo, Philippines. Pinatubo erupted in 1991, filling valleys draining the flanks of the volcano with primarily sand-sized pyroclastic flow debris. Twenty years after the eruption, sand-rich sediment inputs are strongly seasonal, with most sediment input to the channel during the rainy season. During the dry season, flow condenses from a wide braided planform to a single-thread channel in most of the upper basin, extending several km onto the alluvial fan. This change in planform creates similar unit discharge ranges in summer and winter. Lower sediment loads in the dry season drive vertical incision until the bed is sufficiently armored. Incision proceeds downstream in a wave, with increasing sediment transport rates and decreasing grain size with distance downstream, eventually reaching a gravel-sand transition and return to a braided planform. Incision depths in the gravel-bedded section exceeded 3 meters in parts of a 4 km-long study reach, a depth too great to be explained by predictions from simple winnowing during incision. Instead, lateral migration into sand-rich alluvium provides sufficient fine sediment to break up the armor surface, allowing incision to start anew and increasing the total depth of the seasonally-incised valley. Lateral migration is recorded in a series of inset terraces within the valley. The importance of sand on channel behavior thus extends beyond transport rates, affecting the depth of incision and volume of material excavated during a rainy to dry season transition.

A composite numerical model for assessing subsurface transport of oily wastes and chemical constituents

NASA Astrophysics Data System (ADS)

Panday, S.; Wu, Y. S.; Huyakorn, P. S.; Wade, S. C.; Saleem, Z. A.

1997-02-01

Subsurface fate and transport models are utilized to predict concentrations of chemicals leaching from wastes into downgradient receptor wells. The contaminant concentrations in groundwater provide a measure of the risk to human health and the environment. The level of potential risk is currently used by the U.S. Environmental Protection Agency to determine whether management of the wastes should conform to hazardous waste management standards. It is important that the transport and fate of contaminants is simulated realistically. Most models in common use are inappropriate for simulating the migration of wastes containing significant fractions of nonaqueous-phase liquids (NAPLs). The migration of NAPL and its dissolved constituents may not be reliably predicted using conventional aqueous-phase transport simulations. To overcome this deficiency, an efficient and robust regulatory assessment model incorporating multiphase flow and transport in the unsaturated and saturated zones of the subsurface environment has been developed. The proposed composite model takes into account all of the major transport processes including infiltration and ambient flow of NAPL, entrapment of residual NAPL, adsorption, volatilization, degradation, dissolution of chemical constituents, and transport by advection and hydrodynamic dispersion. Conceptually, the subsurface is treated as a composite unsaturated zone-saturated zone system. The composite simulator consists of three major interconnected computational modules representing the following components of the migration pathway: (1) vertical multiphase flow and transport in the unsaturated zone; (2) areal movement of the free-product lens in the saturated zone with vertical equilibrium; and (3) three-dimensional aqueous-phase transport of dissolved chemicals in ambient groundwater. Such a composite model configuration promotes computational efficiency and robustness (desirable for regulatory assessment applications). Two examples are presented to demonstrate the model verification and a site application. Simulation results obtained using the composite modeling approach are compared with a rigorous numerical solution and field observations of crude oil saturations and plume concentrations of total dissolved organic carbon at a spill site in Minnesota, U.S.A. These comparisons demonstrate the ability of the present model to provide realistic depiction of field-scale situations.