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Sample records for mackenzie delta nwt

  1. Oceanic storm surges in the outer Mackenzie Delta, NWT Canada: Remote Sensing of tundra disturbance and restoration from saline intrusion

    NASA Astrophysics Data System (ADS)

    Lapka, Stephanie D.

    As the Circumpolar Arctic continues to undergo strong environmental change - such as increased annual temperatures and decreased sea ice cover - natural disturbances are occurring at frequencies and magnitudes never before recorded (Chapin et al. 2000; Manson and Solomon 2007; Shaver and Kummerow 1992). Coastlines and low-lying terrain have been predicted to be among the environments most susceptible to disturbance events, especially within the western Canadian Arctic (Forbes 2011; Lantuit et al. 2011). In September 1999, an oceanic storm surge occurred over the alluvial islands of the outer Mackenzie Delta, NWT Canada. The salt water incursion killed more than 250 km 2 of freshwater tundra. Over a decade later, dead vegetation remains the dominant land cover for more than one quarter of the impacted region. Dynamic retrospective studies such as the one conducted here are important tools for properly monitoring current processes and forecasting future impacts within Arctic landscapes (Hilbert 2006). Landsat imagery has provided the data needed to perform an ecological assessment distinctive from almost all vegetation-based studies conducted within the Circumpolar Arctic to date. Completed within this thesis is a land cover map time series with close to annual coverage between 1972 and 2010 of the alluvial islands in the outer Mackenzie Delta, as well as the first landscape-level vegetation recovery assessment of the area from the largest oceanic storm surge event to have occurred there in the past 1,000 years.

  2. The impacts of thawing permafrost on tundra lakes, Mackenzie Delta region, NWT, Canada. (Invited)

    NASA Astrophysics Data System (ADS)

    Kokelj, S.; Thompson, M. S.; Lantz, T.; Thienpont, J.; Pisaric, M. F.; Smol, J. P.; Blais, J.; Zajdlik, B.

    2009-12-01

    Many arctic regions with abundant lakes and ponds are characterized by ice-rich terrain sensitive to thermokarst disturbance. In the Mackenzie Delta region, retrogressive thaw slumps commonly develop adjacent to tundra lakes and may impact several hectares of terrain. The numbers, size and growth rates of slumps have increased significantly since the 1970s with rising air and permafrost temperatures. To examine the chemical effects of thawing permafrost on lake water quality we assessed water chemistry for large number of slump-disturbed and undisturbed lakes across tundra uplands in the Mackenzie Delta region. The environmental factors typically evoked to explain variation in tundra lake water quality, including surficial geology and proximity to the treeline or to the coast, were subordinate to the main driver, permafrost degradation. Thaw slump-affected lakes had elevated ionic concentrations and water clarity in comparison with undisturbed lakes. The strength of the ionic impact was positively associated with the proportion of catchment affected by slumping and inversely related to disturbance age. We also found that fire-induced active-layer deepening had a detectable influence on lake water ionic strength. Preliminary evidence suggests sedimentary diatom assemblages track the changes in chemical and physical limnology coincident with the timing of thermokarst slumping, and thus, may prove a valuable tool for inferring changes at the base of the aquatic food web in these lakes. In a warming arctic, we can anticipate that thermokarst processes will increase in importance as a driver of ionic chemistry and optical properties of small lakes and ponds with potential to alter aquatic food webs.

  3. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  4. Passive acoustic derived bubble flux and applications to natural gas seepage in the Mackenzie Delta, NWT, Canada and Coal Oil Point, CA

    NASA Astrophysics Data System (ADS)

    Culling, D.; Leifer, I.; Dallimore, S.; Alcala, K.

    2012-12-01

    Minnaert equation predicts. Furthermore, bubbles from a cohesive media escaped in pulses of multiple bubbles, which caused significant inter-bubble acoustic coupling and mud-bubble interaction. The acoustic signature of subsurface bubble migration and concurrent sediment movements, including bubble pinch off, presented additional complexities. Use of passive acoustic derived flux was applied to natural gas seepage in the Mackenzie Delta in the North West Territories, Canada as well as offshore Coal Oil Point (COP), CA. Video data were used to calibrate the COP acoustic observations and showed a strong current impact for non-cohesive sediments. Seepage flux in the delta (cohesive sediments) was calibrated using a custom turbine tent that directly measured flux. Further applications of passive acoustic-derived seep fluxes include monitoring of marine pipelines for leaks, and studying biogenic wetlands ebullition as well as thermogenic and hydrate seepage.

  5. Overview of the science activities for the 2002 Mallik gas hydrate production research well program, Mackenzie Delta, N.W.T., Canada

    NASA Astrophysics Data System (ADS)

    Dallimore, S. R.; Collett, T. S.; Uchida, T.; Weber, M.

    2003-04-01

    With the completion of scientific studies undertaken as part of the 1998 Mallik 2L-38 gas hydrate research well, an international research site was established for the study of Arctic natural gas hydrates in the Mackenzie Delta of northwestern Canada. Quantitative well log analysis and core studies reveal multiple gas hydrate layers from 890 m to 1106 m depth, exceeding 110 m in total thickness. High gas hydrate saturation values, which in some cases exceed 80% of the pore volume, establish the Mallik gas hydrate field as one of the most concentrated gas hydrate reservoirs in the world. Beginning in December 2001 and continuing to the middle of March 2002, two 1188 m deep science observation wells were drilled and instrumented and a 1166 m deep production research well program was carried out. The program participants include 8 partners; The Geological Survey of Canada (GSC), The Japan National Oil Corporation (JNOC), GeoForschungsZentrum Potsdam (GFZ), United States Geological Survey (USGS), United States Department of the Energy (USDOE), India Ministry of Petroleum and Natural Gas (MOPNG)/Gas Authority of India (GAIL) and the Chevron-BP-Burlington joint venture group. In addition the project has been accepted as part of the International Scientific Continental Drilling Program. The Geological Survey of Canada is coordinating the science program for the project and JAPEX Canada Ltd. acted as the designated operator for the fieldwork. Primary objectives of the research program are to advance fundamental geological, geophysical and geochemical studies of the Mallik gas hydrate field and to undertake advanced production testing of a concentrated gas hydrate reservoir. Full-scale field experiments in the production well monitored the physical behavior of the hydrate deposits in response to depressurization and thermal stimulation. The observation wells facilitated cross-hole tomography and vertical seismic profile experiments (before and after production) as well as

  6. Proterozoic Carbonate Lithofacies Control the Distribution of Sulphides at the Gayna River Zn-Pb Camp, Mackenzie Mountains, NWT

    NASA Astrophysics Data System (ADS)

    Turner, E. C.

    2009-05-01

    Zn-Pb deposits at Gayna River, NWT are predominantly concentrated in the informal 'Grainstone formation', a dolostone of the early Neoproterozoic Little Dal Group (Mackenzie Mountains Supergroup). Previous work showed that the mineralisation (inferred 50 Mt combined from numerous zones; 5 percent combined Zn+Pb) is fracture-controlled and spatially associated with giant stromatolite reefs (500 m thick) of the underlying formation. The rheologically brittle, uncompactable and hydrologically tight reef masses are enclosed by coeval, compacted shale and deep-water limestone. A long and complex history of reef growth controlled by sea-level change resulted in a distinctive reef morphology that includes a sharp right-angle at all reef-top margins, where heterogeneous, off-reef limestone, shale and dolostone abut the rigid, lithologically homogeneous reefs. These zones of abrupt lateral facies change, between uncompactable reef and ductile, layered off-reef strata, represent the structurally weakest points in the system, where, during even subtle later tectonic events, stress would be preferentially accommodated. Brittle deformation of competent carbonate layers in this inflection zone in response to stress produced fracture haloes around reef-tops, which were then occluded by Zn-Pb sulphides. Abrupt competence contrasts appear to be necessary for the production of fractures that control the locations of sulphides at Gayna River. The dominant fractures in the Gayna River camp are those associated with reef- tops. The plan shape and location of buried reef-tops are probably the most critical controls on the distribution of hitherto undiscovered sulphide masses in the subsurface. Careful mapping of those depositional lithofacies that are characteristic of near-reef environments and of subtle, compaction-related dips in appropriate stratigraphic levels may provide vectors to as-yet unrecognised subsurface reef-margin zones favourable for Zn-Pb mineralisation. Structures and

  7. Mackenzie River Delta morphological change based on Landsat time series

    NASA Astrophysics Data System (ADS)

    Vesakoski, Jenni-Mari; Alho, Petteri; Gustafsson, David; Arheimer, Berit; Isberg, Kristina

    2015-04-01

    Arctic rivers are sensitive and yet quite unexplored river systems to which the climate change will impact on. Research has not focused in detail on the fluvial geomorphology of the Arctic rivers mainly due to the remoteness and wideness of the watersheds, problems with data availability and difficult accessibility. Nowadays wide collaborative spatial databases in hydrology as well as extensive remote sensing datasets over the Arctic are available and they enable improved investigation of the Arctic watersheds. Thereby, it is also important to develop and improve methods that enable detecting the fluvio-morphological processes based on the available data. Furthermore, it is essential to reconstruct and improve the understanding of the past fluvial processes in order to better understand prevailing and future fluvial processes. In this study we sum up the fluvial geomorphological change in the Mackenzie River Delta during the last ~30 years. The Mackenzie River Delta (~13 000 km2) is situated in the North Western Territories, Canada where the Mackenzie River enters to the Beaufort Sea, Arctic Ocean near the city of Inuvik. Mackenzie River Delta is lake-rich, productive ecosystem and ecologically sensitive environment. Research objective is achieved through two sub-objectives: 1) Interpretation of the deltaic river channel planform change by applying Landsat time series. 2) Definition of the variables that have impacted the most on detected changes by applying statistics and long hydrological time series derived from Arctic-HYPE model (HYdrologic Predictions for Environment) developed by Swedish Meteorological and Hydrological Institute. According to our satellite interpretation, field observations and statistical analyses, notable spatio-temporal changes have occurred in the morphology of the river channel and delta during the past 30 years. For example, the channels have been developing in braiding and sinuosity. In addition, various linkages between the studied

  8. Assessment of undiscovered oil and gas resources of the Mackenzie Delta province, North America, 2004

    USGS Publications Warehouse

    Henry, Mitchell E.; Ahlbrandt, Thomas S.; Charpentier, Ronald R.; Gautier, Donald L.; Klett, Timothy R.; Pollastro, Richard M.; Schenk, Christopher J.; Ulmishek, Gregory F.

    2006-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 40 trillion cubic feet of undiscovered nonassociated gas, a mean of 10.5 billion barrels of undiscovered oil (with 46.6 trillion cubic feet of associated gas), and a mean of 4.0 billion barrels of undiscovered natural gas liquids in the Mackenzie Delta Province of North America, exclusive of the unassessed deep-water portion of the province.

  9. Origin of polycyclic aromatic hydrocarbons in lake sediments of the Mackenzie Delta.

    PubMed

    Headley, John V; Marsh, Philip; Akre, Christine J; Peru, Kerry M; Lesack, Lance

    2002-08-01

    The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) were assessed in sediment cores from among 14 lakes from three regions comprising a transect across the central Mackenzie Delta. PAHs were consistently found in the lake sediments, with parent concentrations in the 20-200 ng/g range. Concentrations were generally independent of depth in the sediment cores and this pattern was similar among the 3 regions of the delta. Concentrations increased in a westerly direction among the regions. For some lakes, the concentration of PAHs decreased with decreasing flooding frequency, and decreasing sedimentation rates. For the latter, maximum concentrations occurred at shallower depths within the sediment cores as flooding frequency among the lakes decreased. The distributions of C0-C4 alkylated 2- and 3- ring PAHs were consistent with a petrogenic origin, while the corresponding distribution of 4-ring PAHs appears to be more consistent with a biogenic or pyrogenic origin. Based on relative contributions to the overall PAH budget, a petrogenic source appears to be dominant. However, the pyrene/fluoranthene ratio is more consistent with a source derived from peat. The alkylated PAH profiles are inconsistent with those in the Athabasca River system, and supports a previously published hypothesis that the contribution of PAHs from the Athabasca oil sands to the lower Mackenzie River is minimal. A double ratio plot of chrysene vs dibenzothiophene, diagnostic of weathering, suggests most weathering occurred before the sediments were deposited in the lakes, while a double ratio plot of dibenzothiophene vs phenanthrene suggests a common source of PAHs across the delta, despite differing water sources from east to west across the delta. PAH inputs to the delta appear to mirror sediment inputs documented in previous work, where high sediment input from the Mackenzie mainstem during high floods dominates the delta sediment influx and masks any influence of the

  10. Source and composition of sediments and organic carbon delivered to the Mackenzie River delta

    NASA Astrophysics Data System (ADS)

    Vonk, J. E.; Blusztajn, J.; Giosan, L.; Montlucon, D. B.; Graf-Pannatier, E.; Eglinton, T. I.

    2012-12-01

    The Mackenzie River is believed to represent the largest fluvial sediment flux to the Arctic Ocean (124 Mt/yr), delivering as much sediment as all other major Arctic Rivers combined. This flux is based on river inflow prior to its entry into the delta, and consists of Mackenzie River mainstem sediments (103 Mt/yr; including Arctic Red River) entering the delta from the southeast, and Peel River sediments (21 Mt/yr) entering from the southwest. The Mackenzie River delta, the second largest river delta in the world, is covered with thousands of small, shallow lakes. In-lake sedimentation, in addition to overbank and point bar sedimentation, is substantial and estimated to be around 102 Mt/yr. Erosion of banks and channels may account for approximately half of this flux, so the "true" offshore sediment flux might be lower than is typically reported. Improved estimates are required for the flux and provenance of fluvial sediment delivered to the delta, and to the adjacent Beaufort Sea, to be able to increase our understanding of Arctic deltas, particularly in the light of ongoing and future climatic change. Here we investigate the source and composition of sediments in the Mackenzie delta and near-coastal zone, based on a blend of sedimentological (grain size, mineral surface area), organic (%TOC, %TN, δ13C, δ15N, Δ14C) and inorganic (major/trace elements, Nd/Sr isotopes) properties of suspended river particulates (n=6), bank sediments (n=8), lake sediments (n=21), and shelf sediments (n=9). Bank and shelf sediments showed fairly constant bulk %TOC contents and δ13C values (1.0±0.3%, and -26.7±0.3‰; 1.3±0.3%, and -25.5±0.7‰, respectively) whereas lake sediments revealed greater spatial variability (2.2±1.2%, and -26.8±1.3‰). The variability in Nd isotopes of the detrital sediment component is significant (ɛNd of suspended matter -12.7 to -13.9; banks -12.4 to -14.5; lakes -11.4 to -14.5; and shelf -12.5 to -13.0). This suggests strong variations in

  11. Geogenic Sources Strongly Contribute to the Mackenzie River Delta's Methane Emissions Derived From Airborne Flux Data

    NASA Astrophysics Data System (ADS)

    Kohnert, K.; Serafimovich, A.; Metzger, S.; Hartmann, J.; Sachs, T.

    2015-12-01

    Arctic permafrost-associated wetlands and thawing permafrost emit the greenhouse gas methane (CH4), either as a product of recent microbial activity in the active layer or taliks, or from deeper geogenic sources where pathways through the permafrost exist. Current emission estimates vary strongly between different models and there is still disagreement between bottom-up estimates from local field studies and top-down estimates from atmospheric measurements. We use airborne flux data from two campaigns in the Mackenzie River Delta, Canada, in July 2012 and 2013 to directly quantify permafrost CH4 emissions on the regional scale, to analyse the regional pattern of CH4 fluxes and to estimate the contribution of geogenic emissions to the overall CH4 budget of the delta. CH4 fluxes were calculated with a time-frequency resolved version of the eddy covariance technique, resulting in a gridded 100 m x 100 m resolution flux map within the footprints of the flight tracks. We distinguish geogenic gas seeps from biogenic sources by their strength and show that they contribute strongly to the annual CH4 budget of the delta. Our study provides the first estimate of annual CH4 release from the Mackenzie River Delta and the adjacent coastal plain. We show that one percent of the covered area contains the strongest geogenic seeps which contribute disproportionately to the annual emission estimate. Our results show that geogenic CH4 emissions might need more attention, especially in areas where permafrost is vulnerable to thawing sufficiently to create pathways for geogenic gas migration. The presented map can be used as a baseline for future CH4 flux studies in the Mackenzie River Delta.

  12. Investigating the spatial distribution of water levels in the Mackenzie Delta using airborne LiDAR

    USGS Publications Warehouse

    Hopkinson, C.; Crasto, N.; Marsh, P.; Forbes, D.; Lesack, L.

    2011-01-01

    Airborne light detection and ranging (LiDAR) data were used to map water level (WL) and hydraulic gradients (??H/??x) in the Mackenzie Delta. The LiDAR WL data were validated against eight independent hydrometric gauge measurements and demonstrated mean offsets from - 0??22 to + 0??04 m (??< 0??11). LiDAR-based WL gradients could be estimated with confidence over channel lengths exceeding 5-10 km where the WL change exceeded local noise levels in the LiDAR data. For the entire Delta, the LiDAR sample coverage indicated a rate of change in longitudinal gradient (??2H/??x) of 5??5 ?? 10-10 m m-2; therefore offering a potential means to estimate average flood stage hydraulic gradient for areas of the Delta not sampled or monitored. In the Outer Delta, within-channel and terrain gradient measurements all returned a consistent estimate of - 1 ?? 10-5 m m-1, suggesting that this is a typical hydraulic gradient for the downstream end of the Delta. For short reaches (<10 km) of the Peel and Middle Channels in the middle of the Delta, significant and consistent hydraulic gradient estimates of - 5 ?? 10-5 m m-1 were observed. Evidence that hydraulic gradients can vary over short distances, however, was observed in the Peel Channel immediately upstream of Aklavik. A positive elevation anomaly (bulge) of > 0??1 m was observed at a channel constriction entering a meander bend, suggesting a localized modification of the channel hydraulics. Furthermore, water levels in the anabranch channels of the Peel River were almost 1 m higher than in Middle Channel of the Mackenzie River. This suggests: (i) the channels are elevated and have shallower bank heights in this part of the delta, leading to increased cross-delta and along-channel hydraulic gradients; and/or (ii) a proportion of the Peel River flow is lost to Middle Channel due to drainage across the delta through anastamosing channels. This study has demonstrated that airborne LiDAR data contain valuable information describing

  13. Hydrocarbon gases associated with permafrost in the Mackenzie Delta, Northwest Territories, Canada

    USGS Publications Warehouse

    Collett, T.S.; Dallimore, S.R.

    1999-01-01

    Molecular and isotopic analyses of core gas samples from 3 permafrost research core holes (92GSCTAGLU, 92GSCKUMAK, 92GSCUNIPKAT; sample core depths ranging from 0.36 to 413.82 m) in the Mackenzie Delta of the Northwest Territories of Canada reveal the presence of hydrocarbon gases from both microbial and thermogenic sources. Analyses of most headspace and blended gas samples from the ice-bonded permafrost portion of the core holes yielded C1/(C2 + C3) hydrocarbon gas ratios and CH4-C isotopic compositions (??13C CH4) indicative of microbially sourced CH4 gas. However, near the base of ice-bonded permafrost and into the underlying non-frozen stratigraphic section, an increase in ethane (C2) concentrations, decreases in C1/(C2 + C3) hydrocarbon gas ratios, and CH4-C isotopic (??13C CH4) data indicate the presence of hydrocarbon gases derived from a thermogenic source. The thermogenic gas below permafrost in the Mackenzie Delta likely migrated from deeper hydrocarbon accumulations and/or directly from thermally mature hydrocarbon source rocks.

  14. Sharing Remote and Local Information for Tracking Spring Breakup in the Mackenzie Delta and Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Forbes, D. L.; Whalen, D.; Fraser, P.

    2015-12-01

    The Mackenzie Delta is the second largest on the Arctic Ocean, covering 13 000 km2. The annual flood regime in the delta is dominated by the spring snowmelt freshet and associated ice breakup, as water from the south arrives in the ice-covered delta and spreads over bottomfast and adjacent floating sea ice at the delta front. The complex processes of water-ice interaction, flow partitioning, and overbank flooding to replenish waters in 43 000 delta lakes threaten community, transportation, subsistence, and energy infrastructure in the delta. The annual breakup season is a time of rejuvenation, excitement, and anxiety for delta residents and stakeholders. To track the progress of breakup and meet the need for knowledge dissemination to the local communities, a Mackenzie-Beaufort breakup newsletter has been produced by Natural Resources Canada on a quasi-daily basis during the May-June spring flood season for 10 years, and distributed to an e-mail list that grew to over 300 subscribers. This provides near real-time tracking of water levels and breakup using on-line gauges (Environment Canada), daily MODIS satellite imagery (NASA), Landsat imagery (USGS) and intermittent radar imagery (various sources). In earlier years, information was also supplied from field programs operating in the delta during breakup, but changing priorities and funding have reduced the number of outside researchers present during these critical weeks. Meanwhile the number of local contributors has grown, providing observations and photographs to share with the local, regional and global readership. In this way the newsletter evolved into a two-way communication tool and community portal. The newsletter is a chronicle of each breakup season and a key resource for territorial and municipal managers, subsistence organizations, and emergency response agencies, with routine requests for specific imagery in areas of concern. With the completion of 10 years under the present model, we are exploring

  15. Spatial variations in geochemical characteristics of the modern Mackenzie Delta sedimentary system

    NASA Astrophysics Data System (ADS)

    Vonk, Jorien E.; Giosan, Liviu; Blusztajn, Jerzy; Montlucon, Daniel; Graf Pannatier, Elisabeth; McIntyre, Cameron; Wacker, Lukas; Macdonald, Robie W.; Yunker, Mark B.; Eglinton, Timothy I.

    2015-12-01

    The Mackenzie River in Canada is by far the largest riverine source of sediment and organic carbon (OC) to the Arctic Ocean. Therefore the transport, degradation and burial of OC along the land-to-ocean continuum for this riverine system is important to study both regionally and as a dominant representative of Arctic rivers. Here, we apply sedimentological (grain size, mineral surface area), and organic and inorganic geochemical techniques (%OC, δ13C-OC and Δ14C-OC, 143Nd/144Nd, δ2H and δ18O, major and trace elements) on particulate, bank, channel and lake surface sediments from the Mackenzie Delta, as well as on surface sediments from the Mackenzie shelf in the Beaufort Sea. Our data show a hydrodynamic sorting effect resulting in the accumulation of finer-grained sediments in lake and shelf deposits. A general decrease in organic carbon (OC) to mineral surface area ratios from river-to-sea furthermore suggests a loss of mineral-bound terrestrial OC during transport through the delta and deposition on the shelf. The net isotopic value of the terrestrial OC that is lost en route, derived from relationships between δ13C, OC and surface area, is -28.5‰ for δ13C and -417‰ for Δ14C. We calculated that OC burial efficiencies are around 55%, which are higher (∼20%) than other large river systems such as the Amazon. Old sedimentary OC ages, up to 12 14C-ky, suggest the delivery of both a petrogenic OC source (with an estimated contribution of 19 ± 9%) as well as a pre-aged terrestrial OC source. We calculated the 14C-age of this pre-aged, biogenic, component to be about 6100 yrs, or -501‰, which illustrates that terrestrial OC in the watershed can reside for millennia in soils before being released into the river. Surface sediments in lakes across the delta (n = 20) showed large variability in %OC (0.92-5.7%) and δ13C (-30.7‰ to -23.5‰). High-closure lakes, flooding only at exceptionally high water levels, hold high sedimentary OC contents (>2.5%) and

  16. Functional Carbon Processing and Its Linkage to Hydrology in Lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Lesack, L.; Tank, S. E.; Gareis, J.; Chateauvert, C. A.; Squires, M.; Marsh, P.

    2011-12-01

    The circumpolar arctic contains a number of large river deltas that are lake-rich because of thermokarst effects. The Mackenzie Delta is the second largest, containing 45,000 lakes within a floodplain area 1/3rd the size of Switzerland. A 20-year case study has placed the biogeochemistry of these lakes into context via analysis of 40 years of water level records, river-to-lake connectivities, and estimates of annual river-water renewal. The lakes collectively represent gradients from turbid waters to transparent, high dissolved-nutrients to low, low total dissolved organic matter (DOM) to high, high chromophoric-DOM (CDOM) to low, high inorganic content of lake sediments to high organic sediment, and low under-water ultraviolet-irradiance to higher irradiances. Super imposed on these are biotic community production gradients respectively ranging from low production of aquatic bacteria to high, low macrophytes to high, low epiphyton to high, high phytoplankton and epipelon at intermediate flooding-frequencies, low small-bodied zooplankton to high large-bodied, high fish to no fish, and moderate aquatic birds to high. All the above correspond with a gradient of lake flooding regimes with average river-to-lake connection times ranging from >150 days per year in the lowest elevation lakes maintaining near continuous connection with the river over the open-water period to <4.5 days per year in the highest elevation lakes with long and variable disconnection periods from the river. Thermokarst lakes and lake-chain systems represent special cases where lake behaviors may depart from patterns otherwise strongly linked to river-to-lake connection times. Based on work in this system thus far, we propose a new conceptual model of overall carbon processing based on functional groups of organisms and abiotic processes that govern the overall balance between recycling of carbon to the atmosphere as CO2 or CH4, or the accumulation and storage of carbon in lake biomasses, and

  17. Abundance and patterns of transparent exopolymer particles (TEP) in Arctic floodplain lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Chateauvert, C. Adam; Lesack, Lance F. W.; Bothwell, Max L.

    2012-12-01

    The Mackenzie River Delta is a lake-rich arctic floodplain that receives high inputs of dissolved organic matter (DOM) and suspended particulates from allochthonous and autochthonous sources, and may transfer carbon from dissolved to particulate phase via in situ formation of transparent exopolymer particles (TEP). TEP provides food for grazers, surfaces for bacteria, and increased potential for aggregation and sedimentation of organic matter. During open water 2006, we tracked TEP abundances in three Delta lakes representing gradients that include declining river-to-lake connection times, increasing levels of dissolved organic carbon (DOC), and declining chromophoric-DOM (CDOM). Unexpectedly, TEP abundances were highest immediately after the flood, when autochthonous autotrophic production was at a seasonal low and CDOM a seasonal high. Moreover, the lake with the strongest riverine influence and lowest levels of autochthonous autotrophic production had the highest mean TEP-carbon (TEP-C) concentrations among the lakes. The mean proportion of particulate organic carbon (POC) represented by TEP-C increased with increasing river connection time, and appears to represent a substantial proportion of POC in Mackenzie Delta Lakes. Unexpectedly, the TEP gradient was most strongly related to CDOM (river water source) rather than overall DOC. Variations in CDOM accounted for 53% of TEP-C variation among the lakes, indicating allochthonous matter was the most important source of TEP. DOC release from in situ macrophytes during periods of high photosynthesis may contribute to TEP formation in the lake with lowest riverine influence, but pH levels >9.5 driven by the high photosynthetic rates complicate the interpretation of results from this lake.

  18. Combining Geological, Geodetic, and Tide-Gauge Data to Estimate Coastal Subsidence and Flooding Hazards in the Mackenzie Delta, Western Arctic Canada

    NASA Astrophysics Data System (ADS)

    Forbes, D. L.; Craymer, M.; Henton, J.; Herron, T.; Kokelj, S.; Lapelle, E.; Manson, G. K.; Marsh, P.; Mazzotti, S.; Piraszewski, M.; Solomon, S. M.; Whalen, D.

    2007-12-01

    Relative sea-level trends across the Canadian Arctic are highly variable, in part because of the strong imprint of postglacial isostatic adjustment. In many parts of the central Arctic, ongoing uplift exceeds the rate of regional sea-level rise, resulting in continued coastal emergence. In peripheral areas such as the western Arctic coastal plain, models and geological evidence point to ongoing subsidence, adding to relative sea-level (RSL) rise in the Beaufort-Mackenzie region. Additional sources of subsidence in the Mackenzie Delta include long-term sediment loading and sediment compaction, as well as thaw subsidence where thermal changes such as deeper seasonal thaw lead to melting of excess ground ice. Compaction is reduced in ice-bonded sediments and the thickness of ice bonding varies with the depth of permafrost, which ranges from 0 to 100 m in the main body of the Holocene delta and >500 m in areas outside the main valley fill. Ice-bonding is reduced or absent in thaw taliks beneath deep lakes and channels. Differential subsidence rates may play a role in maintaining or expanding lake area on the delta plain and in promoting delta-front erosion. Beginning in 2001, we have established an Arctic network of continuous GPS (CGPS) stations, including CGPS co-located with tide gauges at Tuktoyaktuk and Ulukhaktok. Fixed monuments for episodic GPS observations have been established and occupied repeatedly in the Mackenzie Delta and we are currently developing a network of fixed reflectors for persistent-scatterer InSAR. Velocities from the North American Reference Frame Working Group (consistent with rates from JPL and SOPAC) indicate positive values (uplift) at all CGPS stations, even in the Beaufort-Mackenzie region. However, the long-term tide-gauge record at Tuktoyaktuk shows a 45-year rising RSL trend (1961-2006) of +3.5±1.3 mm/a. If sea-level rise in the Beaufort Sea has been comparable to the global mean trend during this interval, the implied motion at

  19. Spring-Summer Temperatures Since AD 1780 Reconstructed from Stable Oxygen Isotope Ratios in White Spruce Tree-Rings from the Mackenzie Delta, Northwestern Canada

    NASA Technical Reports Server (NTRS)

    Porter, Trevor J.; Pisaric, Michael F. J.; Field, Robert D.; Kokelj, Steven V.; Edwards, Thomas W. D.; deMontigny, Peter; Healy, Richard; LeGrande, Allegra N.

    2013-01-01

    High-latitude delta(exp 18)O archives deriving from meteoric water (e.g., tree-rings and ice-cores) can provide valuable information on past temperature variability, but stationarity of temperature signals in these archives depends on the stability of moisture source/trajectory and precipitation seasonality, both of which can be affected by atmospheric circulation changes. A tree-ring delta(exp 18)O record (AD 1780-2003) from the Mackenzie Delta is evaluated as a temperature proxy based on linear regression diagnostics. The primary source of moisture for this region is the North Pacific and, thus, North Pacific atmospheric circulation variability could potentially affect the tree-ring delta(exp 18)O-temperature signal. Over the instrumental period (AD 1892-2003), tree-ring delta(exp 18)O explained 29% of interannual variability in April-July minimum temperatures, and the explained variability increases substantially at lower-frequencies. A split-period calibration/verification analysis found the delta(exp 18)O-temperature relation was time-stable, which supported a temperature reconstruction back to AD 1780. The stability of the delta(exp 18)O-temperature signal indirectly implies the study region is insensitive to North Pacific circulation effects, since North Pacific circulation was not constant over the calibration period. Simulations from the NASA-GISS ModelE isotope-enabled general circulation model confirm that meteoric delta(exp 18)O and precipitation seasonality in the study region are likely insensitive to North Pacific circulation effects, highlighting the paleoclimatic value of tree-ring and possibly other delta(exp 18)O records from this region. Our delta(exp 18)O-based temperature reconstruction is the first of its kind in northwestern North America, and one of few worldwide, and provides a long-term context for evaluating recent climate warming in the Mackenzie Delta region.

  20. Relationship of gas hydrate concentration to porosity and reflection amplitude in a research well, Mackenzie Delta, Canada

    USGS Publications Warehouse

    Jin, Y.K.; Lee, M.W.; Collett, T.S.

    2002-01-01

    Well logs acquired at the Mallik 2L-38 gas hydrate research well. Mackenzie Delta, Canada, reveal a distinct trend showing that the resistivity of gas-hydrate-bearing sediments increases with increases in density porosities. This trend, opposite to the general trend of decrease in resistivity with porosity, implies that gas hydrates are more concentrated in the higher porosity. Using the Mallik 2L-38 well data, a proportional gas hydrate concentration (PGHC) model, which states that the gas hydrate concentration in the sediment's pore space is linearly proportional to porosity, is proposed for the general habitat of gas hydrate in sediments. Anomalous data (less than 6% of the total data) outside the dominant observed trend can be explained by local geological characteristics. The anomalous data analysis indicates that highly concentrated gas-hydrate-bearing layers would be expected where sediments have high proportions of gravel and coarse sand. Using the parameters in the PGHC model determined from resistivity-porosity logs, it is possible to qualitatively predict the degree of reflection amplitude variations in seismic profiles. Moderate-to-strong reflections are expected for the Mallik 2L-38 well. ?? 2002 Elsevier Science Ltd. All rights reserved.

  1. Numerical studies of gas production from several CH4 hydrate zones at the Mallik site, Mackenzie Delta, Canada

    USGS Publications Warehouse

    Moridis, G.J.; Collett, T.S.; Dallimore, S.R.; Satoh, T.; Hancock, S.; Weatherill, B.

    2004-01-01

    The Mallik site represents an onshore permafrost-associated gas hydrate accumulation in the Mackenzie Delta, Northwest Territories, Canada. A gas hydrate research well was drilled at the site in 1998. The objective of this study is the analysis of various gas production scenarios from five methane hydrate-bearing zones at the Mallik site. In Zone #1, numerical simulations using the EOSHYDR2 model indicated that gas production from hydrates at the Mallik site was possible by depressurizing a thin free gas zone at the base of the hydrate stability field. Horizontal wells appeared to have a slight advantage over vertical wells, while multiwell systems involving a combination of depressurization and thermal stimulation offered superior performance, especially when a hot noncondensible gas was injected. Zone #2, which involved a gas hydrate layer with an underlying aquifer, could yield significant amounts of gas originating entirely from gas hydrates, the volumes of which increased with the production rate. However, large amounts of water were also produced. Zones #3, #4 and #5 were lithologically isolated gas hydrate-bearing deposits with no underlying zones of mobile gas or water. In these zones, thermal stimulation by circulating hot water in the well was used to induce dissociation. Sensitivity studies indicated that the methane release from the hydrate accumulations increased with the gas hydrate saturation, the initial formation temperature, the temperature of the circulating water in the well, and the formation thermal conductivity. Methane production appears to be less sensitive to the specific heat of the rock and of the hydrate, and to the permeability of the formation. ?? 2004 Published by Elsevier B.V.

  2. Seismic Characterization and Continuity Analysis of Gas Hydrate Horizons Near the Mallik Research Wells, Mackenzie Delta, Canada

    NASA Astrophysics Data System (ADS)

    Bellefleur, G.; Riedel, M.; Brent, T.

    2005-12-01

    Gas hydrate deposits in arctic environment generally lack the BSR signature diagnostic of their presence in marine seismic data. The absence of the BSR signature complicates the estimation of the resources within or below the permafrost and the determination of their potential impact on future energy supplies, geohazard and climate change. We present results from a detailed seismic characterization of three gas hydrate horizons (A, B and C) intersected below the permafrost in five wells of the Mallik gas hydrate field located in the Mackenzie delta (Northwest Territories, Canada). The detailed seismic characterization included attribute analyses, synthetic modeling and acoustic impedance inversion and allowed estimation of the lateral continuity of the three horizons in the vicinity of the wells. Vertical Seismic Profiling (VSP) data, 3D and 2D industry seismic data and the 5L/2L-38 geophysical logs (density, P-wave sonic velocity) were used for this study. Synthetic modeling using the sonic and density logs reveals that the base of the lower gas hydrate horizons B and C can be identified on the industry 3D and 2D seismic sections as prominent isolated reflections. The uppermost gas hydrate occurrence (horizon A) and potentially other additional smaller-scale layers are identified only on the higher-resolution VSP data. The 3D industry seismic data set processed to preserve the relative true-amplitudes was used for attribute calculations and acoustic impedance inversion. The attribute maps defined areas of continuous reflectivity for horizons B and C and structural features disrupting them. Results from impedance inversion indicate that such continuous reflectivity around the wells is most likely attributable to gas hydrates. The middle gas hydrate occurrence (horizon B) covers an area of approximately 25 000m2. Horizon C, which marks the base of gas hydrate occurrence zone, extends over a larger area of approximately 120 000m2.

  3. Neural network analysis of crosshole tomographic images: The seismic signature of gas hydrate bearing sediments in the Mackenzie Delta (NW Canada)

    NASA Astrophysics Data System (ADS)

    Bauer, K.; Pratt, R. G.; Haberland, C.; Weber, M.

    2008-10-01

    Crosshole seismic experiments were conducted to study the in-situ properties of gas hydrate bearing sediments (GHBS) in the Mackenzie Delta (NW Canada). Seismic tomography provided images of P velocity, anisotropy, and attenuation. Self-organizing maps (SOM) are powerful neural network techniques to classify and interpret multi-attribute data sets. The coincident tomographic images are translated to a set of data vectors in order to train a Kohonen layer. The total gradient of the model vectors is determined for the trained SOM and a watershed segmentation algorithm is used to visualize and map the lithological clusters with well-defined seismic signatures. Application to the Mallik data reveals four major litho-types: (1) GHBS, (2) sands, (3) shale/coal interlayering, and (4) silt. The signature of seismic P wave characteristics distinguished for the GHBS (high velocities, strong anisotropy and attenuation) is new and can be used for new exploration strategies to map and quantify gas hydrates.

  4. The effect of hydrate content on seismic attenuation: A case study for Mallik 2L-38 well data, Mackenzie delta, Canada

    NASA Astrophysics Data System (ADS)

    Chand, Shyam; Minshull, Tim A.

    2004-07-01

    Observations of velocities in sediments containing gas hydrates show that the strength of sediments increases with hydrate saturation. Hence it is expected that the attenuation of these sediments will decrease with increasing hydrate saturation. However, sonic log measurements in the Mallik 2L-38 well and cross hole tomography measurements in the Mallik field have shown that attenuation increases with hydrate saturation. We studied a range of mechanisms by which increasing hydrate saturation could cause increased attenuation. We found that a difference in permeability between the host sediment and the newly formed hydrate can produce the observed effect. We modelled attenuation in terms of Biot and squirt flow mechanisms in composite media. We have used our model to predict observed attenuations in the Mallik 2L-38 well, Mackenzie Delta, Canada.

  5. Measuring the thicknesses of the freshwater-layer plume and sea ice in the land-fast ice region of the Mackenzie Delta using helicopter-borne sensors

    NASA Astrophysics Data System (ADS)

    Prinsenberg, S. J.; Peterson, I. K.; Holladay, J. S.

    2008-12-01

    Helicopter-borne sensors have been used since the early 1990s to monitor ice properties in support of winter marine transportation along the east coast of Canada. The observations are used in ice chart production and to validate ice hazard identification algorithms using satellite advanced synthetic aperture radar (ASAR) imagery. In this study we evaluated the sensors' additional capability to monitor the freshwater plume characteristic beneath land-fast ice. During the Canadian Arctic Shelf Exchange Study (CASES) data were collected over the Mackenzie Delta in the southern Beaufort Sea where a buoyant river plume exists. Results showed that the electromagnetic-laser system could describe not only the ice properties but also the horizontal distribution of the freshwater plume depths that decreased in depth stepwise offshore as the flow of the buoyant plume was restricted by a series of ridge-rubble fields running parallel to the coast. Relative to the 2 m mean ice thickness, the plume layer depth varied from zero under mobile offshore pack ice to 3 m inshore of the third set of ridge-rubble fields.

  6. Response to Mackenzie

    ERIC Educational Resources Information Center

    Peers, Chris

    2014-01-01

    Chris Peers begins his response to Jim Mackenzie's article, "Peers on Socrates and Plato" by asking "What is the 'masculine imaginary?'" Peers defines the term "imaginary" as it is applied in his article, "Freud, Plato and Irigaray: A Morpho-Logic of Teaching and Learning" (2012) and draws…

  7. Interactions of polychlorinated biphenyls and organochlorine pesticides with sedimentary organic matter of retrogressive thaw slump-affected lakes in the tundra uplands adjacent to the Mackenzie Delta, NT, Canada

    NASA Astrophysics Data System (ADS)

    Eickmeyer, David C.; Kimpe, Linda E.; Kokelj, Steve V.; Pisaric, Michael F. J.; Smol, John P.; Sanei, Hamed; Thienpont, Joshua R.; Blais, Jules M.

    2016-02-01

    Using a comparative spatial analysis of sediment cores from eight lakes in tundra uplands adjacent to the Mackenzie Delta, NT, we examined how the presence of retrogressive thaw slumps on lake shores affected persistent organic pollutant (POPs, including polychlorinated biphenyls and organochlorine pesticides) accumulation in lake sediments. Sediments of slump-affected lakes contained higher total organic carbon (TOC)-normalized POP concentrations than nearby reference lakes that were unaffected by thaw slumps. Mean focus-corrected inorganic sedimentation rates were positively related to TOC-normalized contaminant concentrations, explaining 58-94% of the variation in POP concentrations in sediment, suggesting that reduced organic carbon in slump-affected lake water results in higher concentrations of POPs on sedimentary organic matter. This explanation was corroborated by an inverse relationship between sedimentary POP concentrations and TOC content of the lake water. Inferred chlorophyll a, S2, and S3 carbon fluxes to sediment were not significantly correlated to POP fluxes. Higher POP concentrations observed in sediment of slump-affected lakes are best explained by simple solvent switching processes of hydrophobic organic contaminants onto a smaller pool of available organic carbon when compared to neighboring lakes unaffected by thaw slump development.

  8. Effects of Mackenzie River Discharge and Bathymetry on Sea Ice in the Beaufort Sea

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Hall, D. K.; Rigor, I. G; Li, P.; Neumann, G.

    2014-01-01

    Mackenzie River discharge and bathymetry effects on sea ice in the Beaufort Sea are examined in 2012 when Arctic sea ice extent hit a record low. Satellite-derived sea surface temperature revealed warmer waters closer to river mouths. By 5 July 2012, Mackenzie warm waters occupied most of an open water area about 316,000 sq km. Surface temperature in a common open water area increased by 6.5 C between 14 June and 5 July 2012, before and after the river waters broke through a recurrent landfast ice barrier formed over the shallow seafloor offshore the Mackenzie Delta. In 2012, melting by warm river waters was especially effective when the strong Beaufort Gyre fragmented sea ice into unconsolidated floes. The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean, constituting a stark contrast to the Antarctic that has no such rivers to affect sea ice.

  9. Against "Ressentiment": Response to Mackenzie

    ERIC Educational Resources Information Center

    Dahlbeck, Johan

    2016-01-01

    Johan Dahlbeck works as senior lecturer at Malmo University. His research interest is in the philosophy of education, focusing especially on ethics and the pedagogical implications of Spinoza's philosophy. In this article, he responds to Jim Mackenzie's "Dahlbeck and Pure Ontology" (EJ1105980), which was written in reply to his…

  10. MODFLOW-NWT, A Newton formulation for MODFLOW-2005

    USGS Publications Warehouse

    Niswonger, Richard G.; Panday, Sorab; Ibaraki, Motomu

    2011-01-01

    This report documents a Newton formulation of MODFLOW-2005, called MODFLOW-NWT. MODFLOW-NWT is a standalone program that is intended for solving problems involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation. MODFLOW-NWT must be used with the Upstream-Weighting (UPW) Package for calculating intercell conductances in a different manner than is done in the Block-Centered Flow (BCF), Layer Property Flow (LPF), or Hydrogeologic-Unit Flow (HUF; Anderman and Hill, 2000) Packages. The UPW Package treats nonlinearities of cell drying and rewetting by use of a continuous function of groundwater head, rather than the discrete approach of drying and rewetting that is used by the BCF, LPF, and HUF Packages. This further enables application of the Newton formulation for unconfined groundwater-flow problems because conductance derivatives required by the Newton method are smooth over the full range of head for a model cell. The NWT linearization approach generates an asymmetric matrix, which is different from the standard MODFLOW formulation that generates a symmetric matrix. Because all linear solvers presently available for use with MODFLOW-2005 solve only symmetric matrices, MODFLOW-NWT includes two previously developed asymmetric matrix-solver options. The matrix-solver options include a generalized-minimum-residual (GMRES) Solver and an Orthomin / stabilized conjugate-gradient (CGSTAB) Solver. The GMRES Solver is documented in a previously published report, such that only a brief description and input instructions are provided in this report. However, the CGSTAB Solver (called XMD) is documented in this report. Flow-property input for the UPW Package is designed based on the LPF Package and material-property input is identical to that for the LPF Package except that the rewetting and vertical-conductance correction options of the LPF Package are not available with the UPW Package. Input files constructed for the LPF Package can be used

  11. DELTAE

    SciTech Connect

    Ward, W.C.; Swift, G.W. )

    1993-11-01

    In thermoacoustic engines and refrigerators, and in many simple acoustic systems, a one dimensional wave equation determines the spatial dependence of the acoustic pressure and velocity. DELTAE numerically integrates such wave equations in the acoustic approximation, in gases or liquids, in user-defined geometries. Boundary conditions can include conventional acoustic boundary conditions of geometry and impedance, as well as temperature and thermal power in thermoacoustic systems. DELTAE can be used easily for apparatus ranging from simple duct networks and resonators to thermoacoustic engines refrigerators and combinations thereof. It can predict how a given apparatus will perform, or can allow the user to design an apparatus to achieve desired performance. DELTAE views systems as a series of segments; twenty segment types are supported. The purely acoustic segments include ducts and cones, and lumped impedances including compliances, series impedances, and endcaps. Electroacoustics tranducer segments can be defined using either frequency-independent coefficients or the conventional parameters of loudspeaker-style drivers: mass, spring constant, magnetic field strength, etc. Tranducers can be current driven, voltage driven, or connected to an electrical load impedance. Thermoacoustic segment geometries include parallel plates, circular and rectangular pores, and pin arrays. Side branches can be defined with fixed impedances, frequency-dependent radiation impedances, or as an auxiliary series of segments of any types. The user can select working fluids from among air, helium, neon, argon, hydrogen, deuterium, carbon dioxide, nitrogen, helium-argon mixtures, helium-xenon mixtures, liquid sodium, and eutectic sodium-potassium. Additional fluids and solids can be defined by the user.

  12. Q-Manifolds and Mackenzie Theory

    NASA Astrophysics Data System (ADS)

    Voronov, Theodore Th.

    2012-10-01

    Double Lie algebroids were discovered by Kirill Mackenzie from the study of double Lie groupoids and were defined in terms of rather complicated conditions making use of duality theory for Lie algebroids and double vector bundles. In this paper we establish a simple alternative characterization of double Lie algebroids in a supermanifold language. Namely, we show that a double Lie algebroid in Mackenzie's sense is equivalent to a double vector bundle endowed with a pair of commuting homological vector fields of appropriate weights. Our approach helps to simplify and elucidate Mackenzie's original definition; we show how it fits into a bigger picture of equivalent structures on `neighbor' double vector bundles. It also opens ways for extending the theory to multiple Lie algebroids, which we introduce here.

  13. The Legacy of R. F. Mackenzie.

    ERIC Educational Resources Information Center

    Gordon, David

    1988-01-01

    Reviews the life and work of R.F. Mackenzie, radical and child centered educator. Assesses his views of Scottish education as the protector of the Establishment and of schools as loveless agents of control with no respect for the individual, his criticisms of the curriculum, and his rejection of the examination system. (SV)

  14. Mackenzie obstruction for the existence of a transitive Lie algebroid

    NASA Astrophysics Data System (ADS)

    Yu, L. X.; Mishchenko, A. S.; Gasimov, V.

    2014-10-01

    Let g be a finite-dimensional Lie algebra and L be a Lie algebra bundle (LAB). A given coupling Ξ between the LAB L and the tangent bundle TM of a manifold M generates the so-called Mackenzie obstruction Obs(Ξ) ∈ H 3 ( M; ZL) to the existence of a transitive Lie algebroid (K. Mackenzie, General Theory of Lie Groupoids and Lie Algebroids, 2005, p. 279). We present two cases of evaluating the Mackenzie obstruction. In the case of a commutative algebra g, the group Aut(g) δ is isomorphic to the group of all matrices GL(g) with the discrete topology. We show that the Mackenzie obstruction for coupling Obs(Ξ) vanishes. The other case describes the Mackenzie obstruction for simply connected manifolds. We prove that, for simply connected manifolds, the Mackenzie obstruction is also trivial, i.e. Obs(Ξ) = 0 ∈ H 3( M; ZL; ∇ Z ).

  15. Crustal-scale geological and thermal models of the Beaufort-Mackenzie Basin, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Kröger, Karsten; Lewerenz, Björn

    2010-05-01

    of Tertiary deltaic sequences, AAPG Bulletin, 92(2): 225-247. Kroeger, K.F., di Primio, R. and Horsfield, B., (2009). Hydrocarbon flow modeling in complex structures (Mackenzie Basin, Canada), AAPG Bulletin, 93(9): 1-25. O'Leary, D.M., Ellis, R.M., Stephenson, R.A., Lane, L.S. and Zelt, C.A., 1995. Crustal structure of the northern Yukon and Mackenzie Delta, northwestern Canada, Journal of Geophysical Research 100(B7): 9905-9920. Stephenson, R.A., Coflin, K.C., Lane, L.S. and Dietrich, J.R., 1994. Crustal structure and tectonics of the southeastern Beaufort Sea continental margin, Tectonics, 13(2): 389-400.

  16. Offshore Beaufort-Mackenzie basin and Amauligak oil discovery

    SciTech Connect

    Sharpe, R.J.; Gurba, G.J.; Sleumer, B.H.G.

    1988-01-01

    A variety of complex structural styles and depositional environments host hydrocarbon accumulations in the offshore Beaufort-Mackenzie basin. At present, only one of these, the Amauligak field, appears large enough to serve as a lead project to spur commercial development of the area. All offshore Beaufort discoveries to date occur in sandstones ranging from Paleocene to Oligocene in age. All occur in deltaic or delta-derived sediments ranging from delta-plain deposits to submarine fan/turbidites. In the western Beaufort, sediments are deformed into a series of linear diapiric features interpreted to be thrusted anticlines, possible associated with strike-slip faulting. Similarly, the Tarsiut area immediately to the east is dominated by diapiric anticlines crosscut by a major east-west-trending fault, also possibly a strike-slip fault. In contrast, the central and eastern portions of the offshore Beaufort, where Amauligak is located, are characterized by growth faulting in the sand-rich Oligocene depocenter. To the north, in a basinward direction, unfaulted diapiric anticlines are draped by submarine fans. These structures may in part be related to the gravitational faults to the south. The Amauligak field is located in the growth fault province. It is contained with a large, south-dipping, simple fault-bounded structure in which hydrocarbons are trapped against the north-bounding listric fault. Sediments penetrated at Amauligak include more than 1,500 m of interbedded Oligocene sandstones and shales, the sandstones representing primarily delta-front deposits. Distinctive shale markers are the probable result of the switching of major deltaic lobes.

  17. The Mackenzie GEWEX Study: a Hydrological Overview

    NASA Astrophysics Data System (ADS)

    Woo, M.

    2004-05-01

    Canada participates in the Global Energy and Water Cycle Experiment (GEWEX) of the World Climate Research Program through the Mackenzie GEWEX Study (MAGS). The overall objectives are to understand and model the response of energy and water cycles in northern Canada to climate variability and change, and to apply our predictive capabilities to climatic, water resource and environmental issues. The study comprises an atmospheric and a hydrological component, the latter being the focus of this presentation. In the cold region, snowmelt dominates streamflow generation and frost plays a major role in flow delivery. River ice exaggerates spring flood events while lake storage can seriously affect flow routing. The tundra, mountain and Shield landscapes add variations to the hydrological regimes. Results from the process studies are being incorporated into a hierarchy of models, including a coupled model that combines a regional climate model with a hydrological model through the Canadian land surface scheme. These models will be used to investigate the effects of climate variability and climate change on the atmospheric and hydrological dynamics. Our modelling capability will also be applied to practical issues that includes aviation weather forecasting, impacts of river ice, forest fire and pipeline on the human and natural environments. Knowledge gained from the Mackenzie basin study will be compared with findings from other Continental Scale Experiments and transferred to cold regions within and outside of Canada.

  18. Low-Altitude and Land-Based Infrared Thermography to Identify Types of Groundwater Discharge in NWT Streams

    NASA Astrophysics Data System (ADS)

    Conant, B.; Mochnacz, N. J.

    2009-05-01

    In tributaries of the Mackenzie River in the Northwest Territories (NWT), Canada, groundwater discharge provides critical fish habitat for Dolly Varden and bull trout populations by maintaining base flows, creating thermal refugia in winter, and providing stable riverbed temperatures for spawning. Where temperature contrasts exist between surface water and groundwater, infrared thermography can use heat as a tracer to locate groundwater discharge areas. Thermal images acquired from satellites and high altitude airplanes tend to be expensive, lack the resolution necessary to identify small discharge locations, and do not allow real time decisions to investigate and ground truth identified temperature anomalies. Therefore, a system was developed using a handheld FLIR ThermaCam P25 infrared camera, visual video camera, infrared video capture system, and GPS in a low flying helicopter and on the ground. The advantage of the system was its ability to inexpensively and efficiently characterize several kilometer long reaches of river and identify springs and seeps on a sub-meter scale and in real time. The different types of groundwater discharge that can occur in these streams include: deep geothermally heated groundwater; shallow groundwater; and active zone water, but differentiating them can be difficult because observed thermal anomalies can be non-unique functions of the initial groundwater temperature, magnitude of discharge, air and surface water temperatures, and temporal variations. Work performed in March and September easily detected spring and seeps of deep groundwater (8 to 13 ° C) at Smith Creek, Gibson Creek, Gayna River, and Little Fish Creek. Shallow groundwater discharge was detected (1 to 3 ° C) at White Sand Creek, Canyon Creek, and Fish Creek, but was more difficult to identify. Subtle variations from surrounding temperatures (<1 ° C) at some sites suggested seeps from the hyporheic zone or possibly the active zone. The limitations of infrared

  19. Assessing the Intellectual Ability of Indian and Metis Pupils at Ft. Simpson, N.W.T.

    ERIC Educational Resources Information Center

    MacArthur, R.S.

    The study assessed the general intellectual ability of Indian and Metis pupils of the Northwest Territory (N.W.T.), Canada. While minimizing cultural bias, an attempt was made to identify economical tests for this cultural group which would demonstrate (1) minimal loading on verbal and other culture-bound factors, (2) moderate relationship to…

  20. The Reform Ideas of William Lyon Mackenzie: Jacksonian or Arcadian in Impulse?

    ERIC Educational Resources Information Center

    Bennett, Paul W.

    1987-01-01

    Explores the influence of Jacksonian democracy upon the ideas and activities of William Lyon Mackenzie, a reformer who sparked the 1837 Yonge Rebellion in upper Canada. Examines similarities in several original documents written by Mackenzie and Jackson. (RKM)

  1. Introduction of the 2007-2008 JOGMEC/NRCan/Aurora Mallik Gas Hydrate Production Research Program, NWT, Canada

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Dallimore, S. R.; Numasawa, M.; Yasuda, M.; Fujii, T.; Fujii, K.; Wright, J.; Nixon, F.

    2007-12-01

    Japan Oil, Gas and Metals National Corporation (JOGMEC) and Natural Resource Canada (NRCan) have embarked on a new research program to study the production potential of gas hydrates. The program is being carried out at the Mallik gas hydrate field in the Mackenzie Delta, a location where two previous scientific investigations have been carried in 1998 and 2002. In the 2002 program that was undertaken by seven partners from five countries, 468m3 of gas flow was measured during 124 hours of thermal stimulation using hot warm fluid. Small-scale pressure drawdown tests were also carried out using Schlumberger's Modular Dynamics Tester (MDT) wireline tool, gas flow was observed and the inferred formation permeabilities suggested the possible effectiveness of the simple depressurization method. While the testing undertaken in 2002 can be cited as the first well constrained gas production from a gas hydrate deposit, the results fell short of that required to fully calibrate reservoir simulation models or indeed establish the technical viability of long term production from gas hydrates. The objectives of the current JOGMEC/NRCan/Aurora Mallik production research program are to undertake longer term production testing to further constrain the scientific unknowns and to demonstrate the technical feasibility of sustained gas hydrate production using the depressurization method. A key priority is to accurately measure water and gas production using state-of-art production technologies. The primary production test well was established during the 2007 field season with the re-entry and deepening of JAPEX/JNOC/GSC Mallik 2L-38 well, originally drilled in 1998. Production testing was carried out in April of 2007 under a relatively low drawdown pressure condition. Flow of methane gas was measured from a 12m perforated interval of gas-hydrate-saturated sands from 1093 to 1105m. The results establish the potential of the depressurization method and provide a basis for future

  2. Monitoring ice break-up on the Mackenzie River using MODIS data

    NASA Astrophysics Data System (ADS)

    Muhammad, P.; Duguay, C.; Kang, K.-K.

    2016-03-01

    The aim of this study was to develop an approach for estimating ice break-up dates on the Mackenzie River (MR) using more than a decade of MODIS Level 3 500 m snow products (MOD/MYD10A1), complemented with 250 m Level 1B radiance products (MOD/MYD02QKM) from the Terra and Aqua satellite platforms. The analysis showed break-up began on average between days of year (DOYs) 115 and 125 and ended between DOYs 145 and 155 over 13 ice seasons (2001-2013), resulting in an average melt duration of ca. 30-40 days. Thermal processes were more important in driving ice break-up south of the MR confluence with the Liard River, while dynamically driven break-up was more important north of the Liard. A comparison of the timing of ice disappearance with snow disappearance from surrounding land areas of the MR with MODIS Level 3 snow products showed varying relationships along the river. Ice-off and snow-off timing were in sync north of the MR-Liard River confluence and over sections of the MR before it enters the Mackenzie Delta, but ice disappeared much later than snow on land in regions where thermal ice break-up processes dominated. MODIS observations revealed that channel morphology is a more important control of ice break-up patterns than previously believed with ice runs on the MR strongly influenced by channel morphology (islands and bars, confluences and channel constriction). Ice velocity estimates from feature tracking were able to be made in 2008 and 2010 and yielded 3-4-day average ice velocities of 1.21 and 1.84 m s-1 respectively, which is in agreement with estimates from previous studies. These preliminary results confirm the utility of daily MODIS data for monitoring ice break-up processes along the Mackenzie River. The addition of optical and synthetic aperture radar data from recent and upcoming satellite missions (e.g. Sentinel-1/2/3 and RADARSAT Constellation) would improve the monitoring of ice break-up in narrower sections of the MR.

  3. AmeriFlux US-NR1 Niwot Ridge Forest (LTER NWT1)

    SciTech Connect

    Blanken, Peter

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-NR1 Niwot Ridge Forest (LTER NWT1). Site Description - The Niwot Ridge AmeriFlux site is located in a subalpine forest ecosystem just below the Continental Divide near Nederland, CO. The site is located at 3050 m elevation, within 600m of the NOAA C1 long-term monitoring station, approximately 8 km east of the Continental Divide. The surrounding subalpine forest is ~97 years old and in a state of aggradation, having recovered from early twentieth century logging (Monson, et al. Global Change Biology (2002), 8 459-478).

  4. Hydrological projections of climate change scenarios in the Lena and the Mackenzie basins: modeling and uncertainty issues

    NASA Astrophysics Data System (ADS)

    Gelfan, Alexander; Gustafsson, David; Motovilov, Yury; Arheimer, Berit; Kalugin, Andrei; Krylenko, Inna; Lavrenov, Alexander

    2016-04-01

    The ECOMAG and the HYPE regional hydrological models were setup to assess possible impacts of climate change on the hydrological regime of two pan-Arctic great drainage basins: the Lena and the Mackenzie rivers. We firstly assessed the reliability of the hydrological models to reproduce the historical streamflow series and analyse the hydrological projections from the climate change scenarios. The impacts were assessed in three 30-year periods: early- (2006-2035), mid- (2036-2065) and end-century (2070-2099) using an ensemble of five GCMs and four Representative Concentration Pathways (RCP) scenarios. Results show, particularly, that the basins react with multi-year delay to changes in the RCP2.6 mitigation (peak-and-decline) scenario, and consequently to the potential mitigation measures. Then we assessed the hydrological projections' uncertainty, which is caused by the GCM's and RCP's variabilities, and indicated that the uncertainty rises with the time horizon of the projection and, generally, the uncertainty interval is wider for Mackenzie than for Lena. We finally compare the potential future hydrological impacts predicted based on the GCM-scenario ensemble approach and the delta-change transformation method of the historical observations. We found that the latter method can produce useful information about the climate change impact in the great Arctic rivers, at least for the nearest decades.

  5. Geology and hydrocarbon potential of Mackenzie Valley, Northwest Territories

    SciTech Connect

    Hawkings, T.J.; Bowen, D.

    1988-01-01

    In 1921, the first hole drilled for oil in the Mackenzie Valley, Northwest Territories, located on a natural seep at Norman Wells, made a major discovery in the Kee Scarp Limestone. Since then, in this remove 200,000 km/sup 2/ area, stretching from the Alberta border north to the Artic Circle, a further 500 exploratory wells have been drilled, and there has been one other commercial discovery. In the course of this exploration, however, hydrocarbon shows have been recorded in all the major sequences, ranging in age from Cambrian to Cretaceous. Deposition of Cambrian sands and evaporates was controlled by a series of linear arches that persisted until the Middle Devonian. In the Colville Hills area, a significant gas show has been found in basal sandstones overlain by evaporites. Throughout the Ordovician and Silurian, thick sequences of evaporities and carbonates were laid down. These sequences are generally nonprospective except in the southwest where a commercial gas field, Kotaneelee, is developed in fractured shoal carbonates. The Middle Devonian Hume and Kee Scarp formations represent periods of reef growth. The Kee Scarp has been extensively explored in the Mackenzie Valley, ad to date, Norman Wells has been the only success. The Hume formation has been less well explored and has potential in pinnacle reefs growing on a shoal carbonate bank. These Paleozoic sequences constitute the primary prospective zones in the Northwest Territories. The Mississippian is only locally preserved. Exploration in the Cretaceous will be primarily stratigraphic as structures have been complexly affected by the Laramide orogeny. In this relatively undrilled area, ongoing exploration has the potential to lead to major discoveries in the Mackenzie Valley.

  6. Chemical quality of water and suspended sediment from the Slave River, NWT, 1990--1994

    SciTech Connect

    Stephens, G.R.; Peddle, J.; McCarthy, L.H.; Williams, T.G.; Robertson, K.; Gregor, D.J.

    1995-12-31

    The Slave River basin, straddling the Alberta-Northwest Territories (NWT) border, faces potential contamination from industrial development and agricultural practices. The Slave River Environmental Monitoring Program was established in 1990 to assess the water and suspended sediment quality in the territorial portion of the river at Fort Smith, NWT. The number of ``above detect`` data for polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated phenolics (CPs) in water was small, while concentrations of those compounds above analytical detection limits were very low. No pesticides were detected in the water during the five-year monitoring period; however, levels of metals were often observed in measurable concentrations, frequently above water quality guidelines. While concentrations were relatively high, the metals were probably not due to anthropogenic activity. Concentrations of polynuclear aromatic hydrocarbons in suspended sediment often exceeded the ``Lowest Effect Level`` guideline established for bottom sediment by the Ontario Ministry of the Environment, but were always well below the ``Severe Effect Level``. Metal levels in suspended sediment varied over the monitoring period and no trends were discernible. The low number of ``above detect`` data for pesticides and chlorinated phenolics in the suspended sediment suggest little potential adverse impact. Concentrations of dioxins and furans were measured, but the levels were very small and the contributing homologues had minimal toxic potential. No detectable levels of 2,3,7,8-TCDD were observed. It was concluded from the extensive data collected during the five-year program that impact from upstream industrial and agricultural sources is, at the present time, negligible.

  7. From Natural to Design River Deltas

    NASA Astrophysics Data System (ADS)

    Giosan, Liviu

    2016-04-01

    Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

  8. Optical Characterisation of Suspended Particles in the Mackenzie River Plume (Canadian Arctic Ocean) and Implications for Ocean Colour Remote Sensing

    NASA Technical Reports Server (NTRS)

    Doxaran, D.; Ehn, J.; Belanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

    2012-01-01

    Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future

  9. A 50% increase in the amount of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Devred, E.; Babin, M.

    2015-01-01

    Global warming has a significant impact at the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitations along the drainage basins of Arctic Rivers. It has also directly impacted land and seawater temperatures with the consequence of melting the permafrost and sea-ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which was sequestered as frozen since the last glacial maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean-colour satellite data and field observations collected in 2009 to estimate the amount of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

  10. A 50 % increase in the mass of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

    NASA Astrophysics Data System (ADS)

    Doxaran, D.; Devred, E.; Babin, M.

    2015-06-01

    Global warming has a significant impact on the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitation along the drainage basins of Arctic rivers. It has also directly impacted land and seawater temperatures with the consequence of melting permafrost and sea ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which has been sequestered in a frozen state since the Last Glacial Maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean color satellite data and field observations collected in 2009 to estimate the mass of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period, the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

  11. Microsomal enzyme activities in beluga whales from the Mackenzie River Delta, Northwest Territories, Canada

    SciTech Connect

    Lockhart, L.; Metner, D.; Muir, D.; Delorme, P.; Dahlke, L.

    1995-12-31

    On two occasions the authors have obtained samples of liver from freshly killed beluga whales harvested by Inuit hunters. The first samples were obtained from whales trapped in the Husky Lakes; with the onset of winter, ice restricted these whales to small breathing holes where they were taken by hunters. They were found to be starving, with body weights about 200 kg less than those expected for whales of their length. Liver mixed-function oxygenase activities, ethoxyresorufin-O-deethylase and aryl hydrocarbon hydroxylase, correlated closely with blubber residues of polychlorinated biphenyls. A second group of whales was taken in the summer hunt in Kugmallit Bay and showed no sign of starvation. The enzyme activities in these whales had weaker statistical relationships to PCB residues. These observations suggested that mobilization of blubber by the starving whales may have released PCBs to act pharmacologically. The authors could not test this hypothesis directly on whales, but an experiment was carried out on laboratory fish to try to examine it. Arctic char were given low dosages of PCB congener 126 and then maintained on diets of full normal ration, half-ration and quarter-ration over a period of 48 weeks, with sub-sampling at intervals. Fish receiving less than maintenance rations responded with decreases in body fat and increases in EROD activities. These laboratory results suggest that correlations between enzymatic activities and PCBs in the starving whales may indeed have been the result of the loss of blubber and concomitant release of PCBs.

  12. Implication of seismic attenuation for gas hydrate resource characterization, Mallik, Mackenzie Delta, Canada

    NASA Astrophysics Data System (ADS)

    Bellefleur, G.; Riedel, M.; Brent, T.; Wright, F.; Dallimore, S. R.

    2007-10-01

    Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate-bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors estimated from zero-offset Vertical Seismic Profiling data acquired at Mallik, Northwest Territories, Canada, demonstrate significant wave attenuation for hydrate-bearing sediments. These results are in agreement with previous attenuation estimates obtained from sonic logs and crosshole data at different frequency intervals. The application of an inverse Q-filter to compensate attenuation effects of permafrost and hydrate-bearing sediments improved the resolution of surface 3D seismic data and its correlation with log data, particularly for the shallowest gas hydrate interval. Compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone. Our results show that characterization of the Mallik gas hydrates with seismic data not corrected for attenuation would tend to overestimate thicknesses and lateral extent of hydrate-bearing strata and hence, the volume of hydrates in place.

  13. Body burden contaminants in whole fish tissue and livers from the Slave River (NWT)

    SciTech Connect

    McCarthy, L.H.; Stephens, G.R.; Peddle, J.; Lafontaine, C.; Whittle, D.M.; Harbicht, S.

    1995-12-31

    The Slave River Environmental Monitoring Program was established in 1990 to assess whether the commercial and subsistence fisheries in the region were being impacted by downstream transport and subsequent bioaccumulation of contaminants in the fish. Lake whitefish (Coregonus clupeaformis), northern pike (Esox lucius), burbot (Lota lota), walleye (Stizostedion vitreum), and longnose suckers (Catostomus catostomus) were collected in the Slave River at Fort Smith (NWT) and whole fish tissue was evaluated for contaminant accumulation. Due to their high lipid concentration and their importance as food source, burbot livers were also analyzed. A broad organochlorine scan was conducted for selected dioxins and furans, total PCB concentrations and individual congeners, pesticide residues such as DDT and its metabolites, dieldrin, lindane, mirex, and toxaphene. Also, PAHs, and various chlorinated phenolics such as chlorophenols, chlorocatechols, and chloroguaiacols were also examined. Although contaminants were detected in the fish, concentrations generally were minimal. Levels of total PCBs in whole fish tissue ranged from 0.006 to 0.08 mg/kg, while average concentrations in burbot livers were 0.23 mg/kg. The toxic dioxin isomer 2,3,7,8-TCDD was detected once in whole fish tissue (walleye) at levels of 0.86 pg/g, while concentrations in burbot livers ranged from 1.2 to 9.96 pg/g. Higher levels of TCDD (11.4 pg/g) were noted in fish caught at the reference site Chitty/Alexie Lake, although this body of water has no known sources of dioxins and furans. The presence of these compounds indicates a long-range transport and deposition mechanism. Toxaphene concentrations in fish averaged 0.3 mg/kg, while concentrations of p,p{prime}-DDE ranged from 0.001 to 0.008 mg/kg over the monitoring period. Levels of PAHs and chlorinated phenolics were generally below analytical detection limits, as were most of the pesticide residues.

  14. Alkane, terpene and polycyclic aromatic hydrocarbon geochemistry of the Mackenzie River and Mackenzie shelf: Riverine contributions to Beaufort Sea coastal sediment

    NASA Astrophysics Data System (ADS)

    Yunker, Mark B.; Macdonald, Robie W.; Cretney, Walter J.; Fowler, Brian R.; McLaughlin, Fiona A.

    1993-07-01

    To study the largest source of river sediment to the Arctic Ocean, we have collected suspended particulates from the Mackenzie River in all seasons and sediments from the Mackenzie shelf between the river mouth and the shelf edge. These samples have been analyzed for alkanes, triterpenes and polycyclic aromatic hydrocarbons (PAHs). We found that naturally occurring hydrocarbons predominate in the river and on the shelf. These hydrocarbons include biogenic alkanes and triterpenes with a higher plant/peat origin, diagenetic PAHs from peat and plant detritus, petrogenic alkanes, triterpenes and PAHs from oil seeps and/or bitumens and combustion PAHs that are likely relict in peat deposits. Because these components vary independently, the season is found to strongly influence the concentration and composition of hydrocarbons in the Mackenzie River. While essentially the same pattern of alkanes, diagenetic hopanes and alkyl PAHs is observed in all river and most shelf sediment samples, alkane and triterpene concentration variations are strongly linked to the relative amount of higher plant/peat material. Polycyclic aromatic hydrocarbon molecular-mass profiles also appear to be tied primarily to varying proportions of peat, with an additional petrogenic component which is most likely associated with lithic material mobilized by the Mackenzie River at freshet. Consistent with the general lack of alkyl PAHs in peat, the higher PAHs found in the river are probably derived from forest and tundra fires. A few anthropogenic/pyrogenic compounds are manifest only at the shelf edge, probably due to a weakening of the river influence. We take this observation of pyrogenic PAHs and the pronounced source differences between two sediment samples collected at the shelf edge as evidence of a transition from dominance by the Mackenzie River to the geochemistry prevalent in Arctic regions far removed from major rivers.

  15. Nile Delta

    Atmospheric Science Data Center

    2013-04-15

    article title:  The Nile River Delta     View Larger Image ... of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids ...

  16. The Influence of Volcanological and Sedimentological Processes on Diamond Grade Distribution: Examples From the Ekati Diamond Mine, NWT, Canada

    NASA Astrophysics Data System (ADS)

    Porritt, L. A.; Cas, R. A.; Ailleres, L.; Oshust, P.

    2009-05-01

    The study of the diamond distribution within two kimberlite pipes, Fox and Koala, from the Ekati Diamond Mine, NWT, Canada, in conjunction with detailed facies models has shown several distinct relationships of deposit type and grade distribution. In both pipes the lithological facies represent grade units which can be distinguished from each other in terms of relative size and abundance of diamonds. Positive correlation of olivine grain size and abundance with diamond grade is seen, indicating that density sorting of fragmental kimberlites occurs both in pyroclastic and resedimented deposits. Though surface geological processes do not control the diamond potential of the erupting magma, they can be responsible for concentrating diamonds into economically significant proportions. A good understanding of the eruption, transport and depositional processes responsible for the individual lithological units and the diamond distribution within them is important for successful resource estimation and may lead to recognition of areas suitable for selective mining, making a marginal deposit economic.

  17. Behaviour of lithium and its isotopes during weathering in the Mackenzie Basin, Canada

    NASA Astrophysics Data System (ADS)

    Millot, Romain; Vigier, Nathalie; Gaillardet, Jérôme

    2010-07-01

    We report Li isotopic compositions, for river waters and suspended sediments, of about 40 rivers sampled within the Mackenzie River Basin in northwestern Canada. The aim of this study is to characterize the behaviour of Li and its isotopes during weathering at the scale of a large mixed lithology basin. The Mackenzie River waters display systematically heavier Li isotopic compositions relative to source rocks and suspended sediments. The range in δ 7Li is larger in dissolved load (from +9.3‰ to +29.0‰) compared to suspended sediments (from -1.7‰ to +3.2‰), which are not significantly different from δ 7Li values in bedrocks. Our study shows that dissolved Li is essentially derived from the weathering of silicates and that its isotopic composition in the dissolved load is inversely correlated with its relative mobility when compared to Na. The highest enrichment of 7Li in the dissolved load is reported when Li is not or poorly incorporated in secondary phases after its release into solution by mineral dissolution. This counterintuitive observation is interpreted by the mixing of water types derived from two different weathering regimes producing different Li isotopic compositions within the Mackenzie River Basin. The incipient weathering regime characterizing the Rocky Mountains and the Shield areas produces 7Li enrichment in the fluid phase that is most simply explained by the precipitation of oxyhydroxide phases fractionating Li isotopes. The second weathering regime is found in the lowland area and produces the lower δ 7Li waters (but still enriched in 7Li compared to bedrocks) and the most Li-depleted waters (compared to Na). Fractionation factors suggest that the incorporation of Li in clay minerals is the mechanism that explains the isotopic composition of the lowland rivers. The correlation of boron and lithium concentrations found in the dissolved load of the Mackenzie Rivers suggests that precipitation of clay minerals is favoured by the

  18. Sir James Mackenzie: from auricular paralysis and nodal rhythm to auricular fibrillation.

    PubMed

    Lippi, Donatella; Mascia, Giuseppe; Padeletti, Luigi

    2011-09-01

    The aim of this paper is to underline the role of Sir James Mackenzie in stating that atrial fibrillation is a distinct and clinically important arrhythmia and that it is a common condition in patients with cardiac disease. Around 1900, a few clinical researchers were dealing with cardiac arrhythmias with the use of arterial and venous pulse tracings. Sir James Mackenzie, who has been one of the fathers of modern cardiology, introduced registration of the venous pulse at the bedside using the clinical polygraph he had invented. He applied the results of his experimental and clinical discoveries to the explanation of many kinds of arrhythmias before ECG introduction. In our paper, we have especially considered the three steps of his approach to atrial fibrillation, the first two developed in the pre-ECG era. The invention of an instrument of precision, the electrocardiograph, revolutionized the diagnosis of heart disease and catalyzed the formation of cardiology as a specialty. PMID:21476085

  19. The Aoraki Mackenzie International Dark Sky Reserve and light pollution issues in New Zealand

    NASA Astrophysics Data System (ADS)

    Hearnshaw, John

    2015-08-01

    I will discuss the Aoraki Mackenzie International Dark Sky Reserve, recognized by IDA in 2012, and how the reserve is managed and promoted to the public to make them aware of light pollution issues and in order to promote star-gazing and astro-tourism. AMIDSR is the world's largest Dark Sky Reserve recognized by IDA and has gold tier status. We will have a Starlight festival in October to promote the Reserve to the public.

  20. Mackenzie's puzzle--the cornerstone of teaching and research in general practice.

    PubMed

    Murdoch, J C

    1997-10-01

    The new-found popularity of generalism as a political force has emphasized the need to clarify the essential philosophy that underpins its practice, teaching, and research. Drawing on the example of Sir James Mackenzie, the author seeks to clarify certain essential issues that need to be emphasized if we are to promote and develop general practice as a distinct academic discipline. Dissatisfaction, uncertainty about our role, and continuing contact with real people seems to be essential to continuing creativity. PMID:9474833

  1. Mackenzie's puzzle--the cornerstone of teaching and research in general practice.

    PubMed Central

    Murdoch, J C

    1997-01-01

    The new-found popularity of generalism as a political force has emphasized the need to clarify the essential philosophy that underpins its practice, teaching, and research. Drawing on the example of Sir James Mackenzie, the author seeks to clarify certain essential issues that need to be emphasized if we are to promote and develop general practice as a distinct academic discipline. Dissatisfaction, uncertainty about our role, and continuing contact with real people seems to be essential to continuing creativity. PMID:9474833

  2. Northern latitude chemical weathering rates: clues from the Mackenzie River Basin, Canada

    NASA Astrophysics Data System (ADS)

    Millot, Romain; Gaillardet, J. érôme; Dupré, Bernard; Allègre, Claude Jean

    2003-04-01

    The main scope of this study is to investigate parameters controlling chemical weathering rates for a large river system submitted to subarctic climate. More than 110 river water samples from the Mackenzie River system (northern Canada) have been sampled and analyzed for major and trace elements and Sr isotopic ratios in the dissolved phase. The three main morphological units are reflected in water chemistry. Rivers from the Canadian Shield are very dilute, dominated by silicate weathering (Millot et al., 2002), whereas the rivers of the Rocky and Mackenzie Mountains as well as the rivers of the sedimentary Interior Platform are dominated by carbonate weathering and are SO 4 rich. Compared to the rivers of the Mackenzie and Rocky Mountains, the rivers of the interior plains are organic, silica, and Na rich and constitute the dominant input term to the Mackenzie River mainstream. Rivers of the Canadian Shield area do not significantly contribute to the Mackenzie River system. Using elemental ratios and Sr isotopic ratios, a mathematical inversion procedure is presented that distinguishes between solutes derived from silicate weathering and solutes derived from carbonate weathering. Carbonate weathering rates are mostly controlled by runoff, which is higher in the mountainous part of the Mackenzie basin. These rates are comparable to the carbonate weathering rates of warmer areas of the world. It is possible that part of the carbonate weathering is controlled by sulfide oxidative weathering, but its extent remains difficult to assess. Conversely to what was stated by Edmond and Huh (1997), overall silicate weathering rates in the Mackenzie basin are low, ranging from 0.13 to 4.3 tons/km 2/yr (Na + K + Ca + Mg), and confirm the negative action of temperature on silicate weathering rates for river basins in cold climates. In contrast to what has been observed in other large river systems such as the Amazon and Ganges Rivers, silicate weathering rates appear 3 to 4

  3. Genetics, recruitment, and migration patterns of Arctic Cisco (Coregonus autumnalis) in the Colville River, Alaska and Mackenzie River, Canada

    USGS Publications Warehouse

    Zimmerman, Christian E.; Ramey, Andy M.; Turner, S.; Mueter, Franz J.; Murphy, S.; Nielsen, Jennifer L.

    2013-01-01

    Arctic cisco Coregonus autumnalis have a complex anadromous life history, many aspects of which remain poorly understood. Some life history traits of Arctic cisco from the Colville River, Alaska, and Mackenzie River basin, Canada, were investigated using molecular genetics, harvest data, and otolith microchemistry. The Mackenzie hypothesis, which suggests that Arctic cisco found in Alaskan waters originate from the Mackenzie River system, was tested using 11 microsatellite loci and a single mitochondrial DNA gene. No genetic differentiation was found among sample collections from the Colville River and the Mackenzie River system using molecular markers (P > 0.19 in all comparisons). Model-based clustering methods also supported genetic admixture between sample collections from the Colville River and Mackenzie River basin. A reanalysis of recruitment patterns to Alaska, which included data from recent warm periods and suspected changes in atmospheric circulation patterns, still finds that recruitment is correlated to wind conditions. Otolith microchemistry (Sr/Ca ratios) confirmed repeated, annual movements of Arctic cisco between low-salinity habitats in winter and marine waters in summer.

  4. Sulfur Isotopes in the Rivers of the Mackenzie River Basin: Implication for CO2 Consumption

    NASA Astrophysics Data System (ADS)

    Calmels, D.; Gaillardet, J.; Brenot, A.; France-Lanord, C.

    2004-12-01

    Mass budgets of chemical weathering in hydro-systems usually assume that the dissolution of CO2 in rain and soil waters provides most of the protons that attack rock minerals. However, the oxidative weathering of reduced species containing sulfur, such as pyrite, can be a significant source of protons. On a global scale, the origin of sulfate in rivers is still unclear. At least three possibilities can be envisaged: sulfate from sedimentary gypsum, atmospheric pollution and oxidative weathering of sulfide. As shown by previous studies, S and O isotopes of the sulfate molecule can allow deciphering between the different sources. In the aim of constraining the origin of sulfate delivered to the ocean by rivers and to refine CO2 consumption budgets for chemical weathering reactions, we have started to measure S and O isotopes in the largest river systems. Among them, the Mackenzie River basin is an ideal case, because it has been recognized by geologists to contain both gypsum and reduced sediments, mainly black-shales, rich in pyrite. The O and S isotopes of the sulfate molecule do show large discrepancies between the two main geomorphic units of the Mackenzie River basin: the Rocky-Mackenzie Mountains to the West and the interior platform to the East. For example, river samples from the lowlands are characterized by values of δ 34S ranging from \\ -3.25‰ to \\ -18.47‰ and those from the mountains varying between 2.06\\permil and 9.87\\permil. We interpret these values and the relationships between isotopic composition of sulfate and major elements as showing the dominant contribution of sulfide oxidation in the lowlands and gypsum dissolution in the mountains. The details of our mixing model, e.g. end-member choices, will be discussed in detail; but based on our data we calculate that 54 to 96% and 18 to 40% of dissolved sulfate come from sulfide oxidation in lowland rivers and mountain rivers, respectively. The mean value obtained for the Mackenzie River Basin

  5. Results of exploratory drilling at Point MacKenzie, Alaska, 1981

    USGS Publications Warehouse

    Patrick, Leslie

    1981-01-01

    The Matanuska-Susitna Borough anticipates industrial development near Point MacKenzie, Alaska. Because little hydrologic information is available for the area, the Borough contracted for the drilling of two test wells. It was found that: Both wells penetrated unconsolidated stratified clay, silt, sand, and gravel; each well penetrated a shallow unconfined and deeper confined aquifers; the water levels in the wells rise and fall with the tide; the chemical analyses indicate that the water quality meets the Alaska Drinking Water Standards, except for slightly high levels of manganese and pH; and the potential for saltwater intrusion should be evaluated as part of future studies. (USGS)

  6. Relation between gas hydrate and physical properties at the Mallik 2L-38 research well in the Mackenzie delta

    USGS Publications Warehouse

    Winters, W.J.; Dallimore, S.R.; Collett, T.S.; Jenner, K.A.; Katsube, J.T.; Cranston, R.E.; Wright, J.F.; Nixon, F.M.; Uchida, T.

    2000-01-01

    As part of an interdisciplinary field program, a 1150-m deep well was drilled in the Canadian Arctic to determine, among other goals, the location, characteristics, and properties of gas hydrate. Numerous physical properties of the host sediment were measured in the laboratory and are presented in relation to the lithology and quantity of in situ gas hydrate. Profiles of measured and derived properties presented from that investigation include: sediment wet bulk density, water content, porosity, grain density, salinity, gas hydrate content (percent occupancy of non-sediment grain void space), grain size, porosity, and post-recovery core temperature. The greatest concentration of gas hydrate is located within sand and gravel deposits between 897 and 922 m. Silty sediment between 926 and 952 m contained substantially less, or no, gas hydrate perhaps because of smaller pore size.

  7. Integrated regional assessment of global climatic change: lessons from the Mackenzie Basin Impact Study (MBIS)

    NASA Astrophysics Data System (ADS)

    Cohen, Stewart J.

    1996-04-01

    This paper outlines the potential role integrated regional assessments of global climatic change scenarios could play in building better links between science and related policy concerns. The concept is illustrated through description of an ongoing case study from Canada—the Mackenzie Basin Impact Study (MBIS). As part of the Government of Canada's Green Plan, the Global Warming Science Program includes a study of regional impacts of global warming scenarios in the Mackenzie Basin, located in northwestern Canada. The MBIS is a six-year program focussing on potential climate-induced changes in the land and water resource base, and the implications of four scenarios of global climatic change on land use and economic policies in this region. These policy issues include interjurisdictional water management, sustainability of native lifestyles, economic development opportunities (agriculture, forestry, tourism, etc.), sustainability of ecosystems and infrastructure maintenance. MBIS is due to be completed in 1997. MBIS represents an attempt to address regional impacts by incorporating a "family of integrators" into the study framework, and by directly involving stakeholders in planning and research activities. The experience in organizing and carrying out this project may provide some lessons for others interested in organizing regional or country studies.

  8. Derivation of Lake Areas and Elevations for the Mackenzie Basin Using Satellite Remote Sensing

    NASA Technical Reports Server (NTRS)

    Birkett, Charon; Kite, Geoff

    1997-01-01

    Modelling hydrological processes in large watersheds flowing to the Arctic ocean is one step towards larger-scale modelling of the global water and energy cycles. Models of the Mackenzie River Basin (Northern Canada) are currently available but omit explicit routing of river flows through the three main lakes - Athabasca, Great Slave Lake and Great Bear Lake (Kite et al, 1994). These lakes occupy an area of 65,000 sq km but little gauge information is available. The levels of the lakes are only measured at a few points on the circumferences and river flows are only measured downstream. The hydraulic relationships between level/discharge and level/area/volume are uncertain. It has been previously shown that satellite remote sensing can be utilised in providing measurements of both lake surface area using imaging techniques and lake level using radar altimetry (Birkett, 1994). Here, we explore the application of these techniques to derive the lake levels and areas for the Mackenzie Basin lakes.

  9. The brucellosis and tuberculosis status of wood bison in the Mackenzie Bison Sanctuary, Northwest Territories, Canada.

    PubMed

    Tessaro, S V; Gates, C C; Forbes, L B

    1993-10-01

    Postmortem examinations were done on 51 wood bison (Bison bison athabascae) killed as part of a multidisciplinary research project in the Mackenzie Bison Sanctuary, Northwest Territories, Canada, between 1986 and 1988. There was no gross, histological or bacteriological evidence of brucellosis or tuberculosis in these bison. Traumatic lesions were seen in one calf that had been attacked by wolves and a second calf that had been gored. Antibody titers to Brucella abortus were not found in sera from these 51 animals or an additional 112 wood bison that were chemically-immobilized or killed in the Sanctuary between 1986 and 1990. The combined prevalence of the diseases in the population could not have exceeded 5.95% for the necropsy survey to have missed finding at least one infected animal, and the prevalence of brucellosis in the population would have had to be less than 1.95% for the broader serological survey to have failed to find at least one reactor animal on the battery of tests. These results, and the cumulative epidemiological information on brucellosis and tuberculosis in bison, indicate that bovine brucellosis and tuberculosis are not enzootic in the wood bison population in and around the Mackenzie Bison Sanctuary, and suggest that the population is free of these diseases. However, this expanding population is at risk of contracting both diseases from the infected bison population in and around nearby Wood Buffalo National Park. PMID:8269360

  10. A crust-scale 3D structural model of the Beaufort-Mackenzie Basin (Arctic Canada)

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Lewerenz, Björn; Kroeger, Karsten Friedrich

    2013-04-01

    The Beaufort-Mackenzie Basin was initiated in the Early Jurassic as part of an Arctic rifted passive continental margin which soon after became overprinted by Cordilleran foreland tectonics. Decades of industrial exploration and scientific research in this petroliferous region have produced a wide spectrum of geological and geophysical data as well as geoscientific knowledge. We have integrated available grids of sedimentary horizons, well data, seismic reflection and refraction data, and the observed regional gravity field into the first crust-scale 3D structural model of the Beaufort-Mackenzie Basin. Many characteristics of this model reflect the complex geodynamic and tectonostratigraphic history of the basin. The Mesozoic-Cenozoic sedimentary part of the model comprises seven clastic units (predominantly sandy shales) of which the modelled thickness distributions allow to retrace the well-established history of the basin comprising a gradual north(east)ward shift of the main depocentres as well as diverse phases of localised erosion. As a result of this development, the present-day configuration of the basin reveals that the sedimentary units tend to be younger, more porous, and thus less dense towards the north at a constant depth level. By integrating three refraction seismic profiles and performing combined isostatic and 3D gravity modelling, we have modelled the sub-sedimentary basement of the Beaufort-Mackenzie Basin. The continental basement spans from unstretched domains (as thick as about 42 km) in the south to extremely thinned domains (of less than 5 km thickness) in the north where it probably represents transitional crust attached to the oceanic crust of the Canada Basin. The uppermost parts of the continental crust are less dense (ρ = 2710 kg/m3) and most probably made up by pre-Mesozoic meta-sediments overlying a heavier igneous and metamorphic crust (ρ = 2850 kg/m3). The presented crust-scale 3D structural model shows that the greatest

  11. Mississippi Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The streamers of clouds draped over the Gulf of Mexico in this true-color MODIS image from February 27, 2002, suggest that a cold, dry wind was blowing southward over the United States and began to pick up moisture over the Gulf, causing these strips of clouds. That the clouds didn't pick up until some distance from the coastline allowed MODIS to get a perfect view of the dynamic Gulf Coast environment spanning (left to right) Texas, Louisiana, Mississippi, Alabama, and Florida's Western Panhandle. The Mississippi River runs roughly down the center of the image, and is joined in Louisiana by the Red River coming in from the northwest. Over the past 7000 years, the actual delta, where the main river channel empties into the Gulf, has wandered around what we now think of as the Louisiana coast. Considering all the sediment visible in this image, it's not hard to imagine that the river carries about 2.4 billion kilograms of sediment into the Gulf each year. Deposition of some of this sediment has been building up the current delta, called the Birdfoot Delta, for obvious reasons, for about 700 years. The coastal waters are alive with microscopic organisms called phytoplankton, which contain colorful pigments, including chlorophyll, for harvesting sunlight. Beyond the sediment plume off Louisiana, the waters are very dark, which could indicate that a large amount of chlorophyll is present, absorbing lots of sunlight and causing the water to appear dark. Farther south, the waters appear bright blue, which could be a signature of coccolithophores, which use highly reflective calcium carbonate to build scaly coverings for themselves. The brighter offshore waters could also be caused by a blue-green algae called Trichodesmium, an organism that can not only harness carbon dioxide for photosynthesis, but can also take nitrogen from the air and turn it into a form that can be used by living organisms. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  12. From rebellious palpitations to the discovery of auricular fibrillation: contributions of Mackenzie, Lewis and Einthoven.

    PubMed

    Silverman, M E

    1994-02-15

    An irregular pulse, referred to as rebellious palpitations, delirium cordis and pulsus irregularis perpetuus, was a cause of speculation by physicians since early times. It was James Mackenzie, a Scottish general practitioner in Burnley, England, utilizing an ink-writing polygraph to record and label jugular venous pulses, who would pioneer in deciphering normal and abnormal cardiac rhythms. His key observation that the jugular "A wave" was lost in a patient who went from a normal to an irregular rhythm provided the first insight into the mechanism of auricular fibrillation. Similar jugular venous and arterial pulse findings were discovered by Cushny, Edmunds and Lewis in directly observed experimental auricular fibrillation. In 1909 Lewis in England and Rothberger and Winterberg in Vienna, taking advantage of Einthoven's newly developed string galvanometer, were the first to establish electrocardiographically that auricular fibrillation was the cause of pulsus irregularis perpetuus. PMID:8109554

  13. Brodsky-Lepage-Mackenzie optimal renormalization scale setting for semihard processes

    NASA Astrophysics Data System (ADS)

    Caporale, F.; Ivanov, D. Yu.; Murdaca, B.; Papa, A.

    2015-06-01

    The Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach for the investigation of semihard processes is plagued by large next-to-leading corrections, both in the kernel of the universal BFKL Green's function and in the process-dependent impact factors, as well as by large uncertainties in the renormalization scale setting. All that calls for an optimization procedure of the perturbative series. In this respect, one of the most common methods is the Brodsky-Lepage-Mackenzie (BLM) one, which eliminates the renormalization scale ambiguity by absorbing the nonconformal β0 terms into the running coupling. In this paper, we apply the BLM scale setting procedure directly to the amplitudes (cross sections) of several semihard processes. We show that, due to the presence of β0 terms in the next-to-leading expressions for the impact factors, the optimal renormalization scale is not universal but depends both on the energy and on the type of process in question.

  14. Monitoring ice break-up on the Mackenzie River, Canada, from MODIS Aqua and Terra observations

    NASA Astrophysics Data System (ADS)

    Muhammad, P.; Duguay, C. R.; Kang, K.

    2013-12-01

    Monitoring the response of river ice phenology to variability and changes in high-latitude climate conditions is critical for improving our understanding of northern hydrology and related impacts on geochemical and biological processes. Shorter ice cover duration, thinner ice, and earlier break-up also influence the winter road season, thereby influencing industrial development and the delivery of goods to northern communities. Increased upstream temperatures over the Mackenzie River Basin have caused shorter ice cover seasons, consequently changing the timing and severity of river ice flow in this high-latitude region. This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 3 500-m snow products (Aqua and Terra), complemented with 250-m Level 1b data, to monitor ice cover during the break-up period on the Mackenzie River over the 2001-2013 period. Results from the analysis of 10 ice seasons (2003-2012) show that first day ice-off was observed between day of year (DY) 115-125 and ended between DY 145-155, resulting in average melt durations of about 30-40 days. Additional ice-on and ice-off days observed during 2003-2012 resulted from northern flowing entrained river ice that extended the break-up season until DY 155-163. Floating ice flowing northbound could therefore generate multiple periods of ice-cover and ice-free days at the same geographic location. During the ice break-up seasons from 2003-2012, ice melt was initiated by in situ melt over drainage basin (thermodynamic), especially between 61-62o N. However, ice break-up above the 62o N was more dynamically driven. In addition, ice jams were found to be largely controlled by river morphology.

  15. Basin-Scale Exports vs. Coastal Delivery of Carbon, Nutrients and Particulates Above and Below Arctic River Deltas

    NASA Astrophysics Data System (ADS)

    Striegl, R. G.; Tank, S. E.; Weeks, G.; Holmes, R. M.; McClelland, J. W.

    2014-12-01

    Recent studies have substantially improved our understanding of water, sediment and materials exports by arctic rivers. Seasonality of exports, particularly during the spring freshet, is better quantified, as are the inland sources of water and sediment discharge and the source and chemical character of other material exports, including carbon and nutrients. Measurements on small rivers discharging directly to the Arctic Ocean and lacking complex deltas can accurately quantify local inputs to coastal regions. However, the majority of hydrologic inputs to the Arctic Ocean derive from 6 major Eurasian and North American rivers. Water, sediment, and chemical exports from these rivers are typically measured above head of tide, far inland, and commonly above large river deltas. These deltas settle particles and provide favorable environments for deposition, storage, and biogeochemical consumption, production, and transformation of aquatic carbon and nutrients. Consequently, basin exports measured above river deltas likely misrepresent actual delivery to coastal regions. In addition to accumulating sediment, observed and modeled arctic delta effects include enrichment of the organic content of suspended solids, increased dissolved organic carbon and nitrogen (DOC; DON) concentration, decreased inorganic nutrient concentration, and settling and likely increased bioavailability of particle associated contaminants, such as mercury. Increased DOC concentration in the Mackenzie River delta has also been associated with a change in DOC quality, with increased potential for biodegradation of DOC and decreased potential for photodegradation of DOC from head of tide to within the delta. For the most part, assessments of differences between head of tide basin exports and coastal delivery tend to be qualitative rather than quantitative, largely because of difficulties quantifying tidally affected flow. This points to the need to resolve data gaps, improve quantitative assessments

  16. Stability Zone of Natural Gas Hydrates in a Permafrost-Bearing Region of the Beaufort-Mackenzie Basin: Study of a Feasible Energy Source (Geological Survey of Canada Contribution No.1999275)

    SciTech Connect

    Majorowicz, J. A. Hannigan, P. K.

    2000-03-15

    Analysis of geological and geophysical data from 150 wells in the Beaufort-Mackenzie region(study area between 68 deg. 30'-70 deg. 00'N and 131 deg. -39 deg. W) led to reinterpretation of the depth of methane hydrate stability and construction of the first contour maps displaying thickness of hydrate stability zones as well as hydrate stability zone thicknesses below permafrost. Calculations were based on construction of temperature-depth profiles incorporating regional heat-flow values, temperature at the base of ice-bearing permafrost, and models relating thermal conductivity with depth. Data analysis indicates the presence and extent of the methane hydrate stability zone is related mainly to the history of permafrost development and less so by the relatively small regional variations of temperature gradients. Analysis of well logs and other indicators in conjunction with knowledge of the hydrate stability zone allows reevaluation of the location of possible gas hydrate occurrences. Log analysis indicates that in the onshore and shallow sea area of the Beaufort-Mackenzie Basin, methane hydrate occurs in 27 wells. Fifteen of these locations coincides with underlying conventional hydrocarbon occurrences. Previous analyses place some of the hydrate occurrences at greater depths than proposed for the methane hydrate stability zone described in this study. Interpretation of geological cross sections reveals that hydrates are related mainly to sandy deltaic and delta-plain deposits in Iperk, Kugmallit, and Reindeer sequences although additional hydrate picks have been inferred in other sequences, such as Richards. Overlying permafrost may act as seal for hydrate accumulations; however, the thickness of permafrost and its related hydrate stability zone fluctuated during geological time. It is interpreted that only in the last tens of thousand of years (i.e., Sangamonian to Holocene), conditions for hydrates changed from nonstable to stable. During Early and Late

  17. Development and application of a groundwater/surface-water flow model using MODFLOW-NWT for the Upper Fox River Basin, southeastern Wisconsin

    USGS Publications Warehouse

    Feinstein, D.T.; Fienen, M.N.; Kennedy, J.L.; Buchwald, C.A.; Greenwood, M.M.

    2012-01-01

    The Fox River is a 199-mile-long tributary to the Illinois River within the Mississippi River Basin in the states of Wisconsin and Illinois. For the purposes of this study the Upper Fox River Basin is defined as the topographic basin that extends from the upstream boundary of the Fox River Basin to a large wetland complex in south-central Waukesha County called the Vernon Marsh. The objectives for the study are to (1) develop a baseline study of groundwater conditions and groundwater/surface-water interactions in the shallow aquifer system of the Upper Fox River Basin, (2) develop a tool for evaluating possible alternative water-supply options for communities in Waukesha County, and (3) contribute to the methodology of groundwater-flow modeling by applying the recently published U.S. Geological Survey MODFLOW-NWT computer code, (a Newton formulation of MODFLOW-2005 intended for solving difficulties involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation) to overcome computational problems connected with fine-scaled simulation of shallow aquifer systems by means of thin model layers. To simulate groundwater conditions, a MODFLOW grid is constructed with thin layers and small cell dimensions (125 feet per side). This nonlinear unconfined problem incorporates the streamflow/lake (SFR/LAK) packages to represent groundwater/surface-water interactions, which yields an unstable solution sensitive to initial conditions when solved using the Picard-based preconditioned-gradient (PCG2) solver. A particular problem is the presence of many isolated wet water-table cells over dry cells, causing the simulated water table to assume unrealistically high values. Attempts to work around the problem by converting to confined conditions or converting active to inactive cells introduce unacceptable bias. Application of MODFLOW-NWT overcomes numerical problem by smoothing the transition from wet to dry cells and keeps all cells active. The simulation is

  18. Mississippi Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Mississippi River delta teems with sediment deposited by the river as it flows into the Gulf of Mexico in this true-color image captured by MODIS on October 15, 2001. The sediment, which is marked by brown swirls in the Gulf, provides nutrients for the bloom of phytoplankton visible as blue-green swirls off the coastline. In the high-resolution image the city of Memphis can be seen in the southwest corner of Tennessee, which is just to left of center at the top of the image. The brown coloration that encompasses Memphis and either side of the river, as flows north to south along the left side of the image, is the river's flood plain. Also visible, in the upper-right hand corner of the image is the southern end of the Appalachian Mountains.

  19. Origin of the Mackenzie large igneous province and sourcing of flood basalts from layered intrusions

    NASA Astrophysics Data System (ADS)

    Day, J. M.; Pearson, D.

    2013-12-01

    The 1.27 Ga Coppermine continental flood basalt (CFB) in northern Canada represents the extrusive manifestation of the Mackenzie large igneous province (LIP) that includes the Mackenzie dyke swarm and the Muskox layered intrusion. New Re-Os isotope and highly siderophile element (HSE: Re, Pd, Pt, Ru, Ir, Os) abundance data are reported together with whole-rock major- and trace-element abundances and Nd isotopes to examine the behaviour of the HSE during magmatic differentiation and to place constraints on the extent of crustal interaction with mantle-derived melts. Mineral-chemical data are also reported for an unusual andesite glass flow (4.9 wt.% MgO) found in proximity to newly recognised picrites (>20 wt.% MgO) in the lowermost stratigraphy of the Coppermine CFB. Compositions of mineral phases in the andesite are similar to equivalent phases found in Muskox Intrusion chromitites and the melt composition is identical to Muskox chromite melt inclusions. Elevated HSE contents (e.g., 3.8 ppb Os) and the mantle-like initial Os isotope composition of this andesitic glass contrast strongly with oxygen isotope and lithophile element evidence for extensive crustal contamination. These signatures implicate an origin for the glass as a magma mingling product formed within the Muskox Intrusion during chromitite genesis. The combination of crust and mantle signatures define roles for both these reservoirs in chromitite genesis, but the HSE appear to be dominantly mantle-sourced. Combined with Nd isotope data that places the feeder for lower Coppermine CFB picrites and basalts within the Muskox Intrusion, this provides the strongest evidence yet for direct processing of some CFB within upper-crustal magma chambers. Modeling of absolute and relative HSE abundances in CFB reveal that HSE concentrations decrease with increasing fractionation for melts with <8×1 wt.% MgO in the Coppermine CFB, with picrites (>13.5wt.% MgO) from CFB having higher Os abundances than ocean island

  20. Delta III—an evolutionary delta growth

    NASA Astrophysics Data System (ADS)

    Arvesen, R. J.; Simpson, J. S.

    1996-03-01

    In order to remain competitive in the future and expand the McDonnell Douglas Aerospace market share, MDA has developed an expendable launch system strategy that devices cost-effective launch systems from the Delta II with a growth vehicle configuration called Delta III. The Delta III evolves from the Delta II launch system through development of a larger payload fairing (4-meter diameter), new cryogenically propelled upper stage, new first stage fuel tank, and larger strap-on solid rocket motors. We are developing the Delta III using Integrated Product Development Teams that capitalize on the experience base that has led us to a world record breaking mission success of 49 consecutive Delta II missions. The Delta III first-launch capability is currently planned for the spring of 1998 in support of our first spacecraft customer, Hughes Space and Communications International.

  1. An Intercomparison of Model Performance and Uncertainty in Forcing Data for the Mackenzie River Basin

    NASA Astrophysics Data System (ADS)

    Sapriza Azuri, G.; Pedinotti, V.; Chun, K. P.; Davison, B.; Pietroniro, A.; Wheater, H. S.

    2014-12-01

    The Mackenzie River Basin (MRB) in Canada has been the focus of many large scale hydrological models. Significant modelling challenges arise, due to the complexities of the cold region hydrology and the current manifestations of climate warming, including permafrost thaw, increased streamflow, tundra shrub expansion, among other processes. Robust large-scale predictive models are necessary for regional and global impacts assessment, along with proper validation and uncertainty estimation of model structure and forcing data. We present an intercomparison of global model performance on the MRB and analysis of the impact of uncertainty in forcing data. With that purpose, we have implemented for the MRB a large-scale model using the Modélisation Environmentale Communautaire - Surface and Hydrology (MESH) model driven with several gridded forcing data sets. We compare the model performance with the Joint UK Land Environment Simulator (JULES), the Weather Research and Forecasting (WRF) and the Variable Infiltration Capacity (VIC) models. Results will be presented to illustrate the comparative performance of water balance components and streamflow simulations. As for the uncertainty in forcing data, precipitation has the major impact, especially the rainfall spatial variability.

  2. Marine heat flow measurements across subsea permafrost limit in the eastern Mackenzie Trough, Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Kim, Y. G.; Hong, J. K.; Jin, Y. K.; Riedel, M.; Melling, H.; Kang, S. G.; Dallimore, S.

    2015-12-01

    Marine heat flow measurements using a 5 m-long Ewing-type heat probe were made during Korean icebreaker R/V Araon's Arctic expeditions (ARA04C in 2013 and ARA05B in 2014) to better know the shallow subsurface thermal structure in the eastern slope of Mackenzie Trough, the Canadian Beaufort Sea, in which associative geological processes of permafrost degradation and gas hydrate dissociation occur because of long-term warming since the Last Glacial Maximum. Heat flow in the continental slope was collected for the first time and is rather higher than those from deep boreholes (up to a few km below the seafloor) in the continental shelf. However, the smaller geothermal gradient and thermal conductivity were observed from sites along a transect line across permafrost limit on the eastern slope of the trough. It is noted that geothermal gradients are relatively constant in the vicinity of permafrost limit but are much smaller (even minus) only at deeper depths with positive bottom water temperature. Reason for such distribution is unclear yet. Based on observed geothermal gradient and bottom water temperature, permafrost table shown in subbottom profile seems to be controlled not by temperature. On the other hand, our finding of permafrost evidence on the other subbottom profile located landward may support that permafrost limit in the trough is along with ~100 m isobath.

  3. The Effect of Vegetation Changes on Precipitation Recycling in the Mackenzie River Basin

    NASA Astrophysics Data System (ADS)

    Snyder, P. K.

    2009-12-01

    Northern Hemisphere high latitude land areas have warmed at rates greater than what can be explained by the atmospheric rise in greenhouse gases alone. Changes in the albedo of the ocean and land, whether from the loss of Arctic Ocean sea ice, changes in land cover, or changes in winter precipitation patterns account for much of the amplified warming. In addition, the development of sea ice is strongly influenced by the discharge of freshwater to the Arctic Ocean and therefore, highlights the importance of the hydrologic cycle in amplifying high-latitude warming. While changes in river discharge can be related to precipitation, snow and ice melt, and human modification of the landscape, natural vegetation changes due to warming are also altering the land surface hydrologic cycle and changing the flux of freshwater to the Arctic Ocean. Analysis of vegetation greenness from satellite imagery shows a strong positive trend as vegetation migration and the introduction of new species respond to climate change. These land surface changes not only affect the surface and lower-tropospheric energy budget, but they also influence the hydrologic cycle through altering the partitioning of transpiration and plant-soil evaporation. This contributes to changes in precipitation recycling and runoff, which can ultimately affect the discharge of freshwater to the Arctic Ocean. To illustrate this mechanism and the role of the land surface in the hydrologic cycle, results of a land cover change and precipitation-recycling analysis using North American Regional Reanalysis data will be presented for the Mackenzie Basin in North America. The precipitation recycling approach presented allows for analysis at a variety of temporal scales, from daily to longer, and produces higher recycling ratios than other approaches that tend to underestimate recycling rates. Additionally, results from a dynamic global vegetation model will be presented to evaluate the potential consequences of continued

  4. delta-Hexachlorocyclohexane (delta-HCH)

    Integrated Risk Information System (IRIS)

    delta - Hexachlorocyclohexane ( delta - HCH ) ; CASRN 319 - 86 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Ass

  5. The influence of volcanological and sedimentological processes on diamond grade distribution in kimberlites: examples from the EKATI Diamond Mine, NWT, Canada

    NASA Astrophysics Data System (ADS)

    Porritt, Lucy A.; Cas, R. A. F.; Ailleres, L.; Oshust, P.

    2011-10-01

    The distribution of diamonds within individual kimberlite pipes is poorly documented in the public domain due to the proprietary nature of the data. The study of the diamond distribution within two pipes, Fox and Koala, from the EKATI Diamond Mine, NWT, Canada, in conjunction with detailed facies models has shown several distinct relationships of deposit type and grade distribution. In both pipes, the lithological facies represent grade units which can be distinguished from each other in terms of relative size and abundance of diamonds. A positive relationship between olivine grain size and abundance with diamond size and abundance is observed, indicating that sorting of fragmental kimberlites influences diamond distribution. Though surface geological processes do not control the diamond potential of the erupting magma, they can be responsible for concentrating diamonds into economically significant proportions. A good understanding of the eruption, transport and depositional processes responsible for the individual lithological units and the diamond distribution within them is important for successful resource estimation. This may lead to recognition of areas suitable for selective mining, making a marginal deposit economic.

  6. Multi-decadal increases in dissolved organic carbon and alkalinity flux from the Mackenzie drainage basin to the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tank, Suzanne E.; Striegl, Robert G.; McClelland, James W.; Kokelj, Steven V.

    2016-05-01

    Riverine exports of organic and inorganic carbon (OC, IC) to oceans are intricately linked to processes occurring on land. Across high latitudes, thawing permafrost, alteration of hydrologic flow paths, and changes in vegetation may all affect this flux, with subsequent implications for regional and global carbon (C) budgets. Using a unique, multi-decadal dataset of continuous discharge coupled with water chemistry measurements for the Mackenzie River, we show major increases in dissolved OC (DOC) and IC (as alkalinity) fluxes since the early 1970s, for a watershed that covers 1.8 M km2 of northwestern Canada, and provides substantial inputs of freshwater and biogeochemical constituents to the Arctic Ocean. Over a 39-year period of record, DOC flux at the Mackenzie mouth increased by 39.3% (44.5 ± 22.6 Gmol), while alkalinity flux increased by 12.5% (61.5 ± 60.1 Gmol). Isotopic analyses and substantial increases in sulfate flux indicate that increases in alkalinity are driven by accelerating sulfide oxidation, a process that liberates IC from rock and soils in the absence of CO2 consumption. Seasonal and sub-catchment trends suggest that permafrost thaw plays an important role in the observed increases in DOC and alkalinity: sub-catchment increases for all constituents are confined to northern, permafrost-affected regions, while observed increases in autumn to winter are consistent with documented landscape-scale changes that have resulted from changing thaw dynamics. This increase in DOC and sulfide-derived alkalinity represents a substantial intensification of land-to-ocean C mobilization, at a level that is significant within the regional C budget. The change we observe, for example, is similar to current and projected future rates of CO2 consumption by weathering in the Mackenzie basin.

  7. Generalization of the Brodsky-Lepage-Mackenzie optimization within the {β }-expansion and the principle of maximal conformality

    NASA Astrophysics Data System (ADS)

    Kataev, A. L.; Mikhailov, S. V.

    2015-01-01

    We discuss generalizations of the Brodsky-Lepage-Mackenzie optimization procedure for renormalization group invariant quantities. In this respect, we discuss in detail the features and construction of the {β } -expansion presentation instead of the standard perturbative series with regard to the Adler D function and Bjorken polarized sum rules obtained in the order of O (αs4) . Based on the {β } expansion, we analyze different schemes of optimization, including the corrected principle of maximal conformality, numerically illustrating their results. We suggest our scheme for the series optimization and apply it to both the above quantities.

  8. Completing the calculation of Brodsky-Lepage-Mackenzie corrections to B{yields}X{sub s}{gamma}

    SciTech Connect

    Misiak, Mikolaj; Poradzinski, Michal

    2011-01-01

    Perturbative O({alpha}{sub s}{sup 2}) corrections to B(B{yields}X{sub s}{gamma}) in the Brodsky-Lepage-Mackenzie approximation receive contributions from two-, three-, and four-body final states. While all the two-body results are well established by now, the other ones have remained incomplete for several years. Here, we calculate the last contribution that has been missing to date, namely, the one originating from interference of the current-current and gluonic dipole operators (K{sub 18}{sup (2){beta}}{sub 0} and K{sub 28}{sup (2){beta}}{sub 0}). Moreover, we confirm all the previously known results for Brodsky-Lepage-Mackenzie corrections to the photon energy spectrum that involve the current-current operators (e.g., K{sub 22}{sup (2){beta}}{sub 0} and K{sub 27}{sup (2){beta}}{sub 0}). Finally, we also confirm the recent findings of Ferroglia and Haisch on self-interference of the gluonic dipole operator (K{sub 88}{sup (2){beta}}{sub 0}).

  9. Sensitivity of Arctic Permafrost Carbon in the Mackenzie River Basin: A substrate addition and incubation experiment

    NASA Astrophysics Data System (ADS)

    Hedgpeth, A.; Beilman, D.; Crow, S. E.

    2014-12-01

    Arctic soil organic matter (SOM) mineralization processes are fundamental to the functioning of high latitude soils in relation to nutrients, stability, and feedbacks to atmospheric CO2 and climate. The arctic permafrost zone covers 25% of the northern hemisphere and contains 1672Pg of soil carbon (C). 88% of this C currently resides in frozen soils that are vulnerable to environmental change. For instance, arctic growing seasons may be lengthened, resulting in an increase in plant productivity and rate of below ground labile C inputs as root exudates. Understanding controls on Arctic SOM dynamics requires recognition that labile C inputs have the potential to significantly affect mineralization of previously stable SOM, also known as 'priming effects'. We conducted a substrate addition incubation experiment to quantify and compare respiration in highly organic (42-48 %C) permafrost soils along a north-south transect in western Canada. Near surface soils (10-20 cm) were collected from permafrost peatland sites in the Mackenzie River Basin from 69.2-62.6°N. The surface soils are fairly young (Δ14C values > -140.0) and can be assumed to contain relatively reactive soil carbon. To assess whether addition of labile substrate alters SOM decomposition dynamics, 4.77-11.75 g of permafrost soil were spiked with 0.5 mg D-glucose g-1 soil and incubated at 5°C. A mass balance approach was used to determin substrate-induced respiration and preliminary results suggest a potential for positive priming in these C-rich soils. Baseline respiration rates from the three sites were similar (0.067-0.263 mg CO2 g-1 soil C) yet show some site-specific trends. The rate at which added substrate was utilized within these soils suggests that other factors besides temperature and soil C content are controlling substrate consumption and its effect on SOM decomposition. Microbial activity can be stimulated by substrate addition to such an extent that SOM turnover is enhanced, suggesting that

  10. Paleolimnological assessment of riverine and atmospheric pathways and sources of metal deposition at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    MacDonald, Lauren A; Wiklund, Johan A; Elmes, Matthew C; Wolfe, Brent B; Hall, Roland I

    2016-02-15

    Growth of natural resource development in northern Canada has raised concerns about the effects on downstream aquatic ecosystems, but insufficient knowledge of pre-industrial baseline conditions continues to undermine ability of monitoring programs to distinguish industrial-derived contaminants from those supplied by natural processes. Here, we apply a novel paleolimnological approach to define pre-industrial baseline concentrations of 13 priority pollutant metals and vanadium and assess temporal changes, pathways and sources of these metals at a flood-prone lake (SD2) in the Slave River Delta (NWT, Canada) located ~500 km north of Alberta's oil sands development and ~140 km south of a former gold mine at Yellowknife, NWT. Results identify that metal concentrations, normalized to lithium concentration, are not elevated in sediments deposited during intervals of high flood influence or low flood influence since onset of oil sands development (post-1967) relative to the 1920-1967 baseline established at SD2. When compared to a previously defined baseline for the upstream Athabasca River, several metal-Li relations (Cd, Cr, Ni, Zn, V) in post-1967 sediments delivered by floodwaters appear to plot along a different trajectory, suggesting that the Peace and Slave River watersheds are important natural sources of metal deposition at the Slave River Delta. However, analysis revealed unusually high concentrations of As deposited during the 1950s, an interval of very low flood influence at SD2, which corresponded closely with emission history of the Giant Mine gold smelter indicating a legacy of far-field atmospheric pollution. Our study demonstrates the potential for paleolimnological characterization of baseline conditions and detection of pollution from multiple pathways in floodplain ecosystems, but that knowledge of paleohydrological conditions is essential for interpretation of contaminant profiles. PMID:26688053

  11. The Current Tectonics of the Yukon and Adjacent Area

    NASA Astrophysics Data System (ADS)

    Hyndman, R. D.; Leonard, L. J.

    2014-12-01

    The current tectonics across the Yukon and adjacent areas of western Northwest Territories (NWT) and northern British Columbia appear to be driven primarily by the Yakutat Terrane collision, an "indenter" in the corner of the Gulf of Alaska. GPS data show 1-10 mm/yr northward and eastward, decreasing inland. The rates from earthquake statistics are similar although there are important discrepancies. The eastern Cordillera earthquake mechanisms are mainly thrust in the Mackenzie Mountains of southwestern NWT where the Cordillera upper crust is overthrusting the craton. To the north, the mechanisms are mainly strike-slip in the Richardson Mountains that appear to lie along the edge of the craton. The deformation appears to be limited to the hot and weak Cordillera with the strong craton providing an irregular eastern boundary. For example, there is an eastward bow in the craton edge and the deformation in the Mackenzie Mountains. On the Beaufort Sea margin in the region of the Mackenzie Delta there appears to be a type of "subduction zone" with the continent very slowly overthrusting the oceanic plate, a process that has continued since at least the Cretaceous. A northward moving continental margin block is bounded by left lateral faulting in the west (Canning Displacement Zone of eastern Alaska) and right lateral faulting in the east (Richardson Mountains in eastern Yukon). There is almost no seismicity on this thrust belt but as for some other subduction zones such as Cascadia there is the potential for very infrequent great earthquakes.

  12. Simulation of Water Sources and Precipitation Recycling for the MacKenzie, Mississippi and Amazon River Basins

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Chern, Jiun-Dar

    2005-01-01

    An atmospheric general circulation model simulation for 1948-1997 of the water budgets for the MacKenzie, Mississippi and Amazon River basins is presented. In addition to the water budget, we include passive tracers to identify the geographic sources of water for the basins, and the analysis focuses on the mechanisms contributing to precipitation recycling in each basin. While each basin s precipitation recycling has a strong dependency on evaporation during the mean annual cycle, the interannual variability of the recycling shows important relationships with the atmospheric circulation. The MacKenzie River basin has only a weak interannual dependency on evaporation, where the variations in zonal moisture transport from the Pacific Ocean can affect the basin water cycle. On the other hand, the Mississippi River basin has strong interannual dependencies on evaporation. While the precipitation recycling weakens with increased low level jet intensity, the evaporation variations exert stronger influence in providing water vapor for convective precipitation at the convective cloud base. High precipitation recycling is also found to be partly connected to warm SSTs in the tropical Pacific Ocean. The Amazon River basin evaporation exhibits small interannual variations, so that the interannual variations of precipitation recycling are related to atmospheric moisture transport from the tropical south Atlantic Ocean. Increasing SSTs over the 50-year period are causing increased easterly transport across the basin. As moisture transport increases, the Amazon precipitation recycling decreases (without real time varying vegetation changes). In addition, precipitation recycling from a bulk diagnostic method is compared to the passive tracer method used in the analysis. While the mean values are different, the interannual variations are comparable between each method. The methods also exhibit similar relationships to the terms of the basin scale water budgets.

  13. Pen Branch delta expansion

    SciTech Connect

    Nelson, E.A.; Christensen, E.J.; Mackey, H.E.; Sharitz, R.R.; Jensen, J.R.; Hodgson, M.E.

    1984-02-01

    Since 1954, cooling water discharges from K Reactor ({anti X} = 370 cfs {at} 59 C) to Pen Branch have altered vegetation and deposited sediment in the Savannah River Swamp forming the Pen Branch delta. Currently, the delta covers over 300 acres and continues to expand at a rate of about 16 acres/yr. Examination of delta expansion can provide important information on environmental impacts to wetlands exposed to elevated temperature and flow conditions. To assess the current status and predict future expansion of the Pen Branch delta, historic aerial photographs were analyzed using both basic photo interpretation and computer techniques to provide the following information: (1) past and current expansion rates; (2) location and changes of impacted areas; (3) total acreage presently affected. Delta acreage changes were then compared to historic reactor discharge temperature and flow data to see if expansion rate variations could be related to reactor operations.

  14. Delta hepatitis in Malaysia.

    PubMed

    Sinniah, M; Dimitrakakis, M; Tan, D S

    1986-06-01

    Sera from one hundred and fifty nine Malaysian individuals were screened for the prevalence of delta markers. These included 15 HBsAg positive homosexuals, 16 acute hepatitis B cases, 9 chronic hepatitis B patients, 13 healthy HBsAg carriers and 106 intravenous (i.v.) drug abusers, of whom 27 were positive for HBsAg only and the rest were anti-HBc IgG positive but HBsAg negative. The prevalence of delta markers in the homosexuals was found to be 6.7%, in the HBsAg positive drug abusers 17.8%, in acute hepatitis B cases 12.5%. No evidence of delta infection was detected in healthy HBsAg carriers, chronic hepatitis B cases and HBsAg negative i.v. drug abusers. With reference to i.v. drug abusers, the prevalence of delta markers was higher in Malays (23%) than in Chinese (7%) although the latter had a higher HBsAg carrier rate. Although the HBsAg carrier rate in the homosexuals was high, their delta prevalence rate was low as compared to drug abusers. In Malaysia, as in other non-endemic regions, hepatitis delta virus transmission appeared to occur mainly via the parenteral and sexual routes. This is the first time in Malaysia that a reservoir of delta infection has been demonstrated in certain groups of the population at high risk for hepatitis B. PMID:3787309

  15. Delta Scuti stars: Theory

    SciTech Connect

    Guzik, J.A.

    1998-03-01

    The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one`s understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying {delta} Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for {delta} Scuti stars, using FG Vir, {delta} Scuti, and CD-24{degree} 7599 as examples.

  16. The Delta Clipper dream

    NASA Astrophysics Data System (ADS)

    Furniss, Tim

    1992-04-01

    A conceptual development status evaluation is presented for the SDIO's projected VTOL SSTOV, dubbed the 'Delta Clipper', which is envisioned as an alternative to the slowly developing NASP and the next-generation National Launch System. Delta Clipper program managers believe that the lightweight materials and structures entailed by the requisite empty/gross-weight ratio for an SSTOV are now available, precluding the airbreathing propulsion of such alternatives as HOTOL. The Delta Clipper could operate with a crew of two, or entirely unmanned. The 8-12 LH2/LOX engines employed are derived from the RL-10 engines of the Centaur launcher.

  17. Modeling river delta formation.

    PubMed

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  18. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  19. Nile Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Nile Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population of 57 million. The capital city of Cairo is at the apex of the delta in the middle of the scene. Across the river from Cairo can be seen the three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  20. Modeling river delta formation

    PubMed Central

    Seybold, Hansjörg; Andrade, José S.; Herrmann, Hans J.

    2007-01-01

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  1. Ecological recovery in an Arctic delta following widespread saline incursion.

    PubMed

    Lantz, Trevor C; Kokelj, Steve V; Fraser, Robert H

    2015-01-01

    Arctic ecosystems are vulnerable to the combined effects of climate change and a range of other anthropogenic perturbations. Predicting the cumulative impact of these stressors requires an improved understanding of the factors affecting ecological resilience. In September of 1999, a severe storm surge in the Mackenzie Delta flooded alluvial surfaces up to 30 km inland from the coast with saline waters, driving environmental impacts unprecedented in the last millennium. In this study we combined field monitoring of permanent sampling plots with an analysis of the Landsat archive (1986-2011) to explore the factors affecting the recovery of ecosystems to this disturbance. Soil salinization following the 1999 storm caused the abrupt dieback of more than 30,000 ha of tundra vegetation. Vegetation cover and soil chemistry show that recovery is occurring, but the rate and spatial extent are strongly dependent on vegetation type, with graminoid- and upright shrub-dominated areas showing recovery after a decade, but dwarf shrub tundra exhibiting little to no recovery over this period. Our analyses suggest that recovery from salinization has been strongly influenced by vegetation type and the frequency of freshwater flooding following the storm. With increased ocean storm activity, rising sea levels, and reduced sea ice cover, Arctic coastal ecosystems will be more likely to experience similar disturbances in the future, highlighting the importance of combining field sampling with regional-scale remote sensing in efforts to detect, understand, and anticipate environmental change. PMID:26255366

  2. Impacts of a recent storm surge on an Arctic delta ecosystem examined in the context of the last millennium.

    PubMed

    Pisaric, Michael F J; Thienpont, Joshua R; Kokelj, Steven V; Nesbitt, Holly; Lantz, Trevor C; Solomon, Steven; Smol, John P

    2011-05-31

    One of the most ominous predictions related to recent climatic warming is that low-lying coastal environments will be inundated by higher sea levels. The threat is especially acute in polar regions because reductions in extent and duration of sea ice cover increase the risk of storm surge occurrence. The Mackenzie Delta of northwest Canada is an ecologically significant ecosystem adapted to freshwater flooding during spring breakup. Marine storm surges during the open-water season, which move saltwater into the delta, can have major impacts on terrestrial and aquatic systems. We examined growth rings of alder shrubs (Alnus viridis subsp. fruticosa) and diatoms preserved in dated lake sediment cores to show that a recent marine storm surge in 1999 caused widespread ecological changes across a broad extent of the outer Mackenzie Delta. For example, diatom assemblages record a striking shift from freshwater to brackish species following the inundation event. What is of particular significance is that the magnitude of this recent ecological impact is unmatched over the > 1,000-year history of this lake ecosystem. We infer that no biological recovery has occurred in this lake, while large areas of terrestrial vegetation remain dramatically altered over a decade later, suggesting that these systems may be on a new ecological trajectory. As climate continues to warm and sea ice declines, similar changes will likely be repeated in other coastal areas of the circumpolar Arctic. Given the magnitude of ecological changes recorded in this study, such impacts may prove to be long lasting or possibly irreversible. PMID:21576496

  3. Man made deltas.

    PubMed

    Maselli, Vittorio; Trincardi, Fabio

    2013-01-01

    The review of geochronological and historical data documents that the largest southern European deltas formed almost synchronously during two short intervals of enhanced anthropic pressure on landscapes, respectively during the Roman Empire and the Little Ice Age. These growth phases, that occurred under contrasting climatic regimes, were both followed by generalized delta retreat, driven by two markedly different reasons: after the Romans, the fall of the population and new afforestation let soil erosion in river catchments return to natural background levels; since the industrial revolution, instead, flow regulation through river dams overkill a still increasing sediment production in catchment basins. In this second case, furthermore, the effect of a reduced sediment flux to the coasts is amplified by the sinking of modern deltas, due to land subsidence and sea level rise, that hampers delta outbuilding and increases the vulnerability of coastal zone to marine erosion and flooding. PMID:23722597

  4. Man made deltas

    PubMed Central

    Maselli, Vittorio; Trincardi, Fabio

    2013-01-01

    The review of geochronological and historical data documents that the largest southern European deltas formed almost synchronously during two short intervals of enhanced anthropic pressure on landscapes, respectively during the Roman Empire and the Little Ice Age. These growth phases, that occurred under contrasting climatic regimes, were both followed by generalized delta retreat, driven by two markedly different reasons: after the Romans, the fall of the population and new afforestation let soil erosion in river catchments return to natural background levels; since the industrial revolution, instead, flow regulation through river dams overkill a still increasing sediment production in catchment basins. In this second case, furthermore, the effect of a reduced sediment flux to the coasts is amplified by the sinking of modern deltas, due to land subsidence and sea level rise, that hampers delta outbuilding and increases the vulnerability of coastal zone to marine erosion and flooding. PMID:23722597

  5. Federal Funding in the Delta.

    ERIC Educational Resources Information Center

    Reeder, Richard J.; Calhoun, Samuel D.

    2002-01-01

    The Lower Mississippi Delta region, especially the rural Delta, faces many economic challenges. The rural Delta has received much federal aid in basic income support and funding for human resource development, but less for community resource programs, which are important for economic development. Federal aid to the Delta is analyzed in terms of…

  6. Man made deltas?

    NASA Astrophysics Data System (ADS)

    Maselli, V.; Trincardi, F.

    2014-12-01

    During the last few millennia, southern European fluvio-deltaic systems have evolved in response to changes in the hydrological cycle, mostly driven by high-frequency climate oscillations and increasing anthropic pressure on natural landscapes. The review of geochronological and historical data documents that the bulk of the four largest northern Mediterranean and Black Sea deltas (Ebro, Rhone, Po and Danube) formed during two short and synchronous intervals during which anthropogenic land cover change was the main driver for enhanced sediment production. These two major growth phases occurred under contrasting climatic regimes and were both followed by generalized delta retreat, supporting the hypothesis of human-driven delta progradation. Delta retreat, in particular, was the consequence of reduced soil erosion for renewed afforestation after the fall of the Roman Empire, and of river dams construction that overkilled the still increasing sediment production in catchment basins since the Industrial Era. In this second case, in particular, the effect of a reduced sediment flux to the coasts is amplified by the sinking of modern deltas, due to land subsidence and sea level rise, that hampers delta outbuilding and increases the vulnerability of coastal zone to marine erosion and flooding.

  7. Deep versus shallow controlling factors of the regional thermal field in the Beaufort-Mackenzie Basin (Arctic Canada)

    NASA Astrophysics Data System (ADS)

    Scheck-Wenderoth, M.; Sippel, J.; Lewerenz, B.

    2011-12-01

    The present-day temperature distribution of the Beaufort-Mackenzie Basin as observed in boreholes indicates large-scale thermal anomalies which have been related to specific tectonic domains and heat transported by convection along major discontinuities (Chen et al., 2008). We have integrated seismic and well data into a crust-scale 3D structural model of the basin, which we have additionally constrained by 3D gravity modelling. This structural model is composed of seven Mesozoic-Cenozoic tectonostratigraphic units which - as a result of a complex foreland depositional and erosional history - tend to be younger, less compacted, and thus less thermally conductive towards the north. The underlying continental crust comprises a low-density upper part (2720 kg/m3 ) and a moderately dense lower part (2850 kg/m3), and it thins considerably towards the north where it passes over to oceanic crust (2900 kg/m2 ). We use the structural model to calculate the 3D conductive thermal field of the basin based on a Finite-Element method, thereby taking one step further towards a quantification of heat transporting processes in this petroliferous region. For the validation of the modelling results, we make use of public domain temperature data from more than 230 wells reaching depths of up to 5000 m. Thermal conductivities are assigned to the different units according to available data sets including also the observed lithology-dependent relationship between conductivity and porosity in the region. The upper boundary condition for the thermal calculations is provided by the well-known depth distribution of the base of permafrost (0 °C isotherm). Assuming a constant heat flow of 30 mW/m2 at the Moho, we find that the modelled temperatures are widely consistent with the observed temperatures in most parts of the basin. Only where large tectonic discontinuities structure the margins of the basin, the misfits are considerable, thus indicating convective heat transport to be an

  8. Delta II Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Final preparations for lift off of the DELTA II Mars Pathfinder Rocket are shown. Activities include loading the liquid oxygen, completing the construction of the Rover, and placing the Rover into the Lander. After the countdown, important visual events include the launch of the Delta Rocket, burnout and separation of the three Solid Rocket Boosters, and the main engine cutoff. The cutoff of the main engine marks the beginning of the second stage engine. After the completion of the second stage, the third stage engine ignites and then cuts off. Once the third stage engine cuts off spacecraft separation occurs.

  9. Lessons from KIPP Delta

    ERIC Educational Resources Information Center

    Maranto, Robert; Shuls, James V.

    2011-01-01

    KIPP Delta succeeds at its stated mission, probably because of its careful attention to culture building. What distinguishes this KIPP school is thoughtful work linking the daily processes of schooling to the goals of schooling, in this case success in college. Day to day tactics reflect broader themes: having a clear mission and hiring staff who…

  10. Delta Airlines LOFT training

    NASA Technical Reports Server (NTRS)

    Whitehead, J.

    1981-01-01

    A LOFT program was developed as part of the DC-9 training program which serves as a prototype for much of Delta's other aircraft training programs. The LOFT used differs little from the ideology presented in the Advisory Circular. Difficulty and experienced concerns regarding the effectiveness of LOFT as a complete training vehicle are explored.

  11. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  12. Using delta-front bathymetry to understand river delta progradation

    NASA Astrophysics Data System (ADS)

    Shaw, J. B.; Mohrig, D. C.

    2010-12-01

    We investigate the delta-front bathymetry of the Wax Lake Delta in Louisiana, USA; a sand rich river delta prograding quickly (~100 m/yr) into a shallow (~2.5 m) basin. The delta-front is the zone separating the bottomset from the topset of the delta. Bottomset sedimentation covers the bed evenly whereas topset sediment transport is focused by flow through distributary channels. The delta front connects these two disparate transport regimes and has a profound effect on channel-network evolution and sedimentary structure of river deltas. Predictions of delta-front topography made by models of delta progradation have rarely been compared to the bathymetry of field-scale deltas. We have mapped 60 km2 of delta front bathymetry immediately seaward of two sub-aerial distributary channels. Subaqueous channels extend up to 2 km seaward of their subaerial portions. These channels lose definition at their distal ends through a combination of channel-bed shoaling and loss of bank relief. Little bathymetric relief is observed at the fronts of the subaqueous channels, calling into question the role of channel-mouth bars in generating the bifurcations observed in this delta-channel network. Near the subaerial to subaqueous transition, steep and eroding sidewalls transition to constructional banks with gentle grades. Grab samples of bed material have been collected throughout the study area in order to detect proximal to distal fining and to constrain the shear stresses connected with delta-front sedimentation. A better understanding of sediment transport in the delta front and its affiliated patterns of erosion and deposition is essential for progress in understanding how river deltas prograde and fill their basins.

  13. The Devil's in the Delta

    ERIC Educational Resources Information Center

    Luyben, William L.

    2007-01-01

    Students frequently confuse and incorrectly apply the several "deltas" that are used in chemical engineering. The deltas come in three different flavors: "out minus in", "big minus little" and "now versus then." The first applies to a change in a stream property as the stream flows through a process. For example, the "[delta]H" in an energy…

  14. Origins of subcalcic garnets and their relation to diamond forming fluids—Case studies from Ekati (NWT-Canada) and Murowa (Zimbabwe)

    NASA Astrophysics Data System (ADS)

    Klein-BenDavid, Ofra; Graham Pearson, D.

    2009-02-01

    Subcalcic, high-Cr (G10) garnets are found as inclusions within diamonds and in peridotitic xenoliths. The strong spatial associations between G10 garnets and diamond make them an important tool in the investigation of diamond genesis. We present an integrated study of the major and trace element composition and oxygen-Sr-Nd-Hf isotopic ratios of eight G10 garnets from the Ekati mine (NWT-Canada) and four from the Murowa mine (Zimbabwe) in an attempt to determine their petrogenetic evolution and to further examine a possible relationship between the metasomatic agents responsible for G10 garnet signatures and diamond forming fluids. All garnets display sinusoidal to mildly sinusoidal REE patterns and have negative Ti, Sr and positive U anomalies. They have variably radiogenic 87Sr/ 86Sr (0.703261-0.731191) and non-radiogenic ɛNd values (-8.1 to -27.1), except for one sample from Murowa that has a positive ɛNd of 2.5. One Ekati sample has an extremely low ɛHf value of -61.6. The Ekati garnets we have studied all appear to come from a single depth in the Slave lithospheric mantle. On the base of Cr-Ca relations they have crystallized at 4.9 GPa and display dunitic Ca intercept values. Their δ 18O values range between +5.23‰ and +5.42‰. The Ekati G10 garnets record a complex, multi-stage metasomatic history involving the interaction of several components during their genesis. One metasomatic agent was enriched in HFSE, LREE, Sr, and depleted in Nb. This agent had the least radiogenic Sr. Another metasomatic agent had highly radiogenic Sr, and was enriched in LREE, Sr, Nb, Th and U. The G10 garnets have very low ɛNd and ɛHf values combined with radiogenic Sr, thus, they require an early lithospheric mantle enrichment event at some stage during their genesis or during the evolution of any precursor material that they formed from. The only Hf isotope composition measurable from the Ekati suite is so unradiogenic ( ɛHf = -61) that it yields a Lu/Hf model age of

  15. Changing Cold Regions: Addressing Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada

    NASA Astrophysics Data System (ADS)

    Pomeroy, J. W.; Wheater, H. S.; Quinton, W. L.; Stewart, R. E.

    2013-05-01

    The cold interior region of Western Canada east of the Continental Divide from the US border to the Arctic Ocean has one of the world's most extreme and variable climates and is experiencing rapid environmental change. Climate warming and precipitation change have resulted in altered patterns of snowfall and snowmelt, conversion of snowfall to rainfall, loss of glaciated area and thawing of permafrost. Effects of these changes on terrestrial ecosystems include changing alpine and arctic treelines, extreme variability in Prairie wetland extent and storage of subsurface water in soil and groundwater, "browning" of the boreal forest and prairie aspen woodlands, forest conversion to wetlands in areas of permafrost loss, increased tundra shrub height and coverage, with associated impacts on snow accumulation and melt and ground thaw regimes. These atmospheric, cryospheric and ecological changes have produced changes to water storage and cycling with lower, earlier and more variable streamflow from the Western Cordillera, earlier and more variable Prairie streamflow, more variable agricultural soil moisture, substantially earlier and sometimes higher streamflows with greater winter baseflows in the North, and indications of changes in extreme precipitation events and resulting flooding and drought. The recently formed Changing Cold Regions Network (CCRN) will investigate the integrated response of mountain, boreal forest, prairie and sub-arctic biomes to climate change at the scales of the Saskatchewan and Mackenzie River Basins and the regional climate system. The multi-prong approach will first inventory and evaluate observable recent change in the Earth system state, fluxes and variability, and then explore the complex interrelationships of changing Earth system processes through the development of improved models and their application in diagnosis and prediction at multiple scales, from small headwater basins to large river basins, major biomes and the regional

  16. DELTAS: A new Global Delta Sustainability Initiative (Invited)

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.

    2013-12-01

    Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

  17. Martian deltas: Morphology and distribution

    NASA Technical Reports Server (NTRS)

    Rice, J. W., Jr.; Scott, D. H.

    1993-01-01

    Recent detailed mapping has revealed numerous examples of Martian deltas. The location and morphology of these deltas are described. Factors that contribute to delta morphology are river regime, coastal processes, structural stability, and climate. The largest delta systems on Mars are located near the mouths of Maja, Maumee, Vedra, Ma'adim, Kasei, and Brazos Valles. There are also several smaller-scale deltas emplaced near channel mouths situated in Ismenius Lacus, Memnonia, and Arabia. Delta morphology was used to reconstruct type, quantity, and sediment load size transported by the debouching channel systems. Methods initially developed for terrestrial systems were used to gain information on the relationships between Martian delta morphology, river regime, and coastal processes.

  18. Understanding pesticides in California's Delta

    USGS Publications Warehouse

    Kuivila, Kathryn M.; Orlando, James L.

    2012-01-01

    The Sacramento-San Joaquin River Delta (Delta) is the hub of California’s water system and also an important habitat for imperiled fish and wildlife. Aquatic organisms are exposed to mixtures of pesticides that flow through the maze of Delta water channels from sources including agricultural, landscape, and urban pest-control applications. While we do not know all of the effects pesticides have on the ecosystem, there is evidence that they cause some damage to organisms in the Delta. Decades of USGS research have provided a good understanding of when, where, and how pesticides enter the Delta. However, pesticide use is continually changing. New field studies and methods are needed so that scientists can analyze which pesticides are present in the Delta, and at what concentrations, enabling them to estimate exposure and ultimate effects on organisms. Continuing research will provide resource managers and stakeholders with crucial information to manage the Delta wisely.

  19. Mississippi River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As the Mississippi 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. 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 stripe running northwest to southeast.

    This image was acquired on May 24, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping

  20. Natural processes in delta restoration: application to the Mississippi Delta.

    PubMed

    Paola, Chris; Twilley, Robert R; Edmonds, Douglas A; Kim, Wonsuck; Mohrig, David; Parker, Gary; Viparelli, Enrica; Voller, Vaughan R

    2011-01-01

    Restoration of river deltas involves diverting sediment and water from major channels into adjoining drowned areas, where the sediment can build new land and provide a platform for regenerating wetland ecosystems. Except for local engineered structures at the points of diversion, restoration mainly relies on natural delta-building processes. Present understanding of such processes is sufficient to provide a basis for determining the feasibility of restoration projects through quantitative estimates of land-building rates and sustainable wetland area under different scenarios of sediment supply, subsidence, and sea-level rise. We are not yet to the point of being able to predict the evolution of a restored delta in detail. Predictions of delta evolution are based on field studies of active deltas, deltas in mine-tailings ponds, experimental deltas, and countless natural experiments contained in the stratigraphic record. These studies provide input for a variety of mechanistic delta models, ranging from radially averaged formulations to more detailed models that can resolve channels, topography, and ecosystem processes. Especially exciting areas for future research include understanding the mechanisms by which deltaic channel networks self-organize, grow, and distribute sediment and nutrients over the delta surface and coupling these to ecosystem processes, especially the interplay of topography, network geometry, and ecosystem dynamics. PMID:21329199

  1. The Beaver River structure: A cross-strike discontinuity of possible crustal dimensions in the southern Mackenzie Fold Belt, Yukon and Northwest territories, Canada

    USGS Publications Warehouse

    Morrow, D.W.; Miles, W.C.

    2000-01-01

    A significant cross-strike structural discontinuity, the Beaver River Structure, has been recognized near the boundary between the north-central part of the Mackenzie Fold Belt and its southern part, the Liard Plateau. The Beaver River Structure is the northeast continuation of the Beaver Fault toward the confluence of the South Nahanni and Liard rivers and into the Interior Platform. It is oriented sub-parallel with the Liard Line farther south. Cumulative Laramide-aged dextral movement of 10 to 20 kilometres is inferred to have occurred along the Beaver River Structure. Small dextral offsets occur along the Beaver Fault, a possible surface manifestation of the Beaver River Structure and large, dominantly north-south oriented Laramide-aged folds and faults, such as the Kotaneelee and Liard synclines and the Nahanni Thrust Fault appear to have been locally rotated in a manner consistent with dextral strike-slip of at least 10 to 20 kilometres. The absence of Permian and Triassic strata in the Mackenzie Fold Belt north of the Beaver River Structure may indicate that uplift and erosion occurred north of the Beaver River Structure during the Early Cretaceous Columbian Orogeny. It is likely that the Beaver River Structure is an ancient, possibly Precambrian, structure that has been reactivated several times throughout Phanerozoic time.

  2. Cadmium and other elements in tissues from four ungulate species from the Mackenzie Mountain region of the Northwest Territories, Canada.

    PubMed

    Larter, N C; Macdonald, C R; Elkin, B T; Wang, X; Harms, N J; Gamberg, M; Muir, D C G

    2016-10-01

    Tissue samples from four ungulate species from the south Mackenzie Mountain region of the Northwest Territories (NT), Canada, were analysed for stable and radioactive elements and (15)N and (13)C stable isotopes. Elevated Cd concentrations in moose (Alces americanus) kidney have been observed in the region and are a health care concern for consumers of traditional foods. This study examined the factors associated with, and potential renal effects from, the accumulation of cadmium, and interactions with other elements in four sympatric ungulate species. Mean renal Cd concentration was highest in moose (48.3mg/kg ww), followed by mountain caribou (Rangifer tarandus caribou) (13.9mg/kg ww) and mountain goat (Oreamnos americanus) (5.78mg/kg ww). No local sources of Cd were evident and the elevated levels in moose are considered to be natural in origin. Conversely, total Hg concentration was significantly higher in mountain caribou kidney (0.21mg/kg ww) than in moose (0.011mg/kg ww). (134)Cs (t½=2.1 y) in mountain goat and Dall's sheep (Ovis dalli) muscle is evidence of deposition from the Fukushima reactor accident in 2011. (137)Cs (t½=30.2 y) in all four ungulates is primarily a remnant of the nuclear weapons tests of the 1960s. The levels of both nuclides are low and the risk to the animals and people consuming them is negligible. Stable isotope δ(15)N and δ(13)C signatures in muscle showed a separation between the mountain caribou, with a lichen-dominated diet, and moose, which browse shrubs and forbs. Isotope signatures for mountain goat and Dall's sheep showed generalist feeding patterns. Differences in elemental and radionuclide levels between species were attributed to relative levels of metal accumulation in the different food items in the diets of the respective species. Kidneys from each species showed minor histological changes in the proximal tubule and glomerulus, although glomerular changes were rare and all changes were rare in mountain goat kidney

  3. Pioneer Launch on Delta Vehicle

    NASA Technical Reports Server (NTRS)

    1969-01-01

    NASA launches the last in the series of interplanetary Pioneer spacecraft, Pioneer 10 from Cape Kennedy, Florida. The long-tank Delta launch vehicle placed the spacecraft in a solar orbit along the path of Earth's orbit. The spacecraft then passed inside and outside Earth's orbit, alternately speeding up and slowing down relative to Earth. The Delta launch vehicle family started development in 1959. The Delta was composed of parts from the Thor, an intermediate-range ballistic missile, as its first stage, and the Vanguard as its second. The first Delta was launched from Cape Canaveral on May 13, 1960 and was powerful enough to deliver a 100-pound spacecraft into geostationary transfer orbit. Delta has been used to launch civil, commercial, and military satellites into orbit. For more information about Delta, please see Chapter 3 in Roger Launius and Dennis Jenkins' book To Reach the High Frontier published by The University Press of Kentucky in 2002.

  4. Delta in Eberswalde

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This HiRISE image covers a portion of a delta that partially fills Eberswalde crater in Margaritifer Sinus. The delta was first recognized and mapped using MOC images that revealed various features whose presence required sustained flow and deposition into a lake that once occupied the crater. The HiRISE image resolves meter-scale features that record the migration of channels and delta distributaries as the delta grew over time. Differences in grain-size of sediments within the environments on the delta enable differential erosion of the deposits. As a result, coarser channel deposits are slightly more resistant and stand in relief relative to finer-grained over-bank and more easily eroded distal delta deposits. Close examination of the relict channel deposits confirms the presence of some meter-size blocks that were likely too coarse to have been transported by water flowing within the channels. These blocks may be formed of the sand and gravel that more likely moved along the channels that was lithified and eroded. Numerous meter-scale polygonal structures are common on many surfaces, but mostly those associated with more quiescent depositional environments removed from the channels. The polygons could be the result of deposition of fine-grained sediments that were either exposed and desiccated (dried out), rich in clays that shrunk when the water was removed, turned into rock and then fractured and eroded, or some combination of these processes.

    Image PSP_001336_1560 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 8, 2006. The complete image is centered at -23.8 degrees latitude, 326.4 degrees East longitude. The range to the target site was 256.3 km (160.2 miles). At this distance the image scale is 25.6 cm/pixel (with 1 x 1 binning) so objects 77 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel and north is up. The image was

  5. Late Pleistocene ice margin fluctuations in the Nahanni National Park-UNESCO World Heritage Site and their impact on glacial lake formation and architecture of drainage systems across the Yukon-NWT continental divide

    NASA Astrophysics Data System (ADS)

    Duk-Rodkin, A.; Barendregt, R. W.

    2009-12-01

    In the late Pleistocene the southern Mackenzie region was glaciated by ice masses from a Cordilleran and continental source (Laurentide). Stratigraphic and geomorphologic evidence indicate that the two glaciers occupied this region at different times during the Late Pleistocene. The continental ice sheet advanced over the foothills and up major valleys reaching its maximum extent, ca. 30 ka. B. P. This took place when Cordilleran glaciers were in their initial stages of development. The Laurentide Ice Sheet blocked the drainage of the South Nahanni River near Virginia Falls, forming a glacial lake which inundated an area of approximately 900 km2 at its maximum stand, and had an outlet to the southwest, across the continental divide into the Yukon Territory and eventually into the Pacific Ocean. Lacustrine sediments at various sites reach thicknesses ranging from 110 to 120 metres, at an elevation of around 700 m. Cordilleran glaciers advanced eastward and approximately 5000 years later blocked this southwestward drainage, rerouting it to the east and north along the Mackenzie Mountain front. The drainage was confined between the mountains and continental ice margin where it incised major canyons into the limestone bedrock, and produced a spectacular karst landscape, which today forms part of the Nahanni National Park. During the retreat of the Laurentide and advance of Cordilleran glaciers, glacial Lake Nahanni cut an outlet to the east at First Canyon. This outlet drained into a continuous northbound network of marginal meltwater channels joining the north-flowing drainage that eventually reached the Arctic Ocean, and during further retreat of the ice sheet established the Mackenzie River in its modern location. The presence of Laurentide ice in this region is evidenced by large granite boulders carried from the Canadian Shield. Erratics are found up to 100 km west of the mountain front. Neotectonic activity in the area is interpreted from exposures such as those

  6. Lift force of delta wings

    SciTech Connect

    Lee, M.; Ho, Chihming )

    1990-09-01

    On a delta wing, the separation vortices can be stationary due to the balance of the vorticity surface flux and the axial convection along the swept leading edge. These stationary vortices keep the wing from losing lift. A highly swept delta wing reaches the maximum lift at an angle of attack of about 40, which is more than twice as high as that of a two-dimensional airfoil. In this paper, the experimental results of lift forces for delta wings are reviewed from the perspective of fundamental vorticity balance. The effects of different operational and geometrical parameters on the performance of delta wings are surveyed.

  7. Holden Crater Delta

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03694 Holden Crater Delta

    This fan-shaped delta deposit is located in Holden Crater.

    Image information: VIS instrument. Latitude -27.3N, Longitude 324.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Shanghai Delta Complex

    SciTech Connect

    Hart, R.E.; Hoffman, P.F.; Parker, R.W.

    1988-01-01

    The upper Eocene Yegua Formation expands dramatically across a regional system of growth faults into an area generally 12-15 km wide, extending at least from the western edge of the Houston sale dome basin to the San Marcos arch. Within this area, the expanded Yegua trend has yielded, since 1982, at least seven noteworthy discoveries: Toro Grande and Lost Bridge fields in Jackson County, and Black Owl, Shanghai, Shanghai East, El Campo, and Phase Four fields in Wharton County. During each of several postulated Yegua sea level drops, this flexure became a focal point for deltaic deposition of excellent reservoir-quality sands. Shanghai, Shanghai East, and El Campo fields are located within what the writers have labeled the ''Shanghai delta complex.'' Integration of seismic and well data in this vicinity shows a marked increase in the expansion indices of growth faults, and moderately thick progradational sand sequences have accumulated immediately downthrow. This structural-stratigraphic pattern, as well as internal bedding characteristics and other lithologic data observed, is believed typical of deltas deposited along the Yegua shelf margin.

  9. Thermostatted delta f

    SciTech Connect

    Krommes, J.A.

    2000-01-18

    The delta f simulation method is revisited. Statistical coarse-graining is used to rigorously derive the equation for the fluctuation delta f in the particle distribution. It is argued that completely collisionless simulation is incompatible with the achievement of true statistically steady states with nonzero turbulent fluxes because the variance of the particle weights w grows with time. To ensure such steady states, it is shown that for dynamically collisionless situations a generalized thermostat or W-stat may be used in lieu of a full collision operator to absorb the flow of entropy to unresolved fine scales in velocity space. The simplest W-stat can be implemented as a self-consistently determined, time-dependent damping applied to w. A precise kinematic analogy to thermostatted nonequilibrium molecular dynamics (NEMD) is pointed out, and the justification of W-stats for simulations of turbulence is discussed. An extrapolation procedure is proposed such that the long-time, steady-state, collisionless flux can be deduced from several short W-statted runs with large effective collisionality, and a numerical demonstration is given.

  10. Delta Electroproduction in 12-C

    SciTech Connect

    Steven McLauchlan

    2003-01-31

    The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4(pie) acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the delta mass was only observed in the exclusive measurements indicating that the delta-nucleus potential is affected by the momentum of the delta.

  11. Inferred gas hydrate and permafrost stability history models linked to climate change in the Beaufort-Mackenzie Basin, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Majorowicz, J.; Safanda, J.; Osadetz, K.

    2012-03-01

    Atmospheric methane from episodic gas hydrate (GH) destabilization, the "clathrate gun" hypothesis, is proposed to affect past climates, possibly since the Phanerozoic began or earlier. In the terrestrial Beaufort-Mackenzie Basin (BMB), GHs occur commonly below thick ice-bearing permafrost (IBP), but they are rare within it. Two end-member GH models, where gas is either trapped conventionally (Case 1) or where it is trapped dynamically by GH formation (Case 2), were simulated using profile (1-D) models and a 14 Myr ground surface temperature (GST) history based on marine isotopic data, adjusted to the study setting, constrained by deep heat flow, sedimentary succession conductivity, and observed IBP and Type I GH contacts in Mallik wells. Models consider latent heat effects throughout the IBP and GH intervals. Case 1 GHs formed at ~0.9 km depth only ~1 Myr ago by in situ transformation of conventionally trapped natural gas. Case 2 GHs begin to form at ~290-300 m ~6 Myr ago in the absence of lithological migration barriers. During glacial intervals Case 2 GH layers expand both downward and upward as the permafrost grows downward through and intercalated with GHs. The distinctive model results suggest that most BMB GHs resemble Case 1 models, based on the observed distinct and separate occurrences of GHs and IBP and the lack of observed GH intercalations in IBP. Case 2 GHs formed >255 m, below a persistent ice-filled permafrost layer that is as effective a seal to upward methane migration as are Case 1 lithological seals. All models respond to GST variations, but in a delayed and muted manner such that GH layers continue to grow even as the GST begins to increase. The models show that the GH stability zone history is buffered strongly by IBP during the interglacials. Thick IBP and GHs could have persisted since ~1.0 Myr ago and ~4.0 Myr ago for Cases 1 and 2, respectively. Offshore BMB IBP and GHs formed terrestrially during Pleistocene sea level low stands. Where

  12. The Changing Cold Regions Network: Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada (Invited)

    NASA Astrophysics Data System (ADS)

    Wheater, H. S.; DeBeer, C.

    2013-12-01

    The cold interior of Northwestern Canada has one of the world's most extreme and varied climates and, as with other regions across the Arctic, is experiencing rapid environmental change. The Changing Cold Regions Network (CCRN) is a new Canadian research network devoted to addressing key challenges and globally-important issues facing the Arctic by improving the understanding of past and ongoing changes in climate, land, vegetation, and water, and predicting their future integrated responses, with a geographic focus on the Saskatchewan and Mackenzie River Basins. The network is funded for 5 years (2013-18) by the Natural Sciences and Engineering Research Council of Canada, and combines the unique expertise of 36 Canadian scientists representing 8 universities and 4 Federal government agencies, as well as 15 international researchers from the United States, China, Australia, the UK, France, and Germany. The network will also involve the World Climate Research Programme, NASA, the Canadian Space Agency, and the National Center for Atmospheric Research. CCRN will integrate existing and new experimental data with modelling and remote sensing products to understand, diagnose and predict changing land, water and climate, and their interactions and feedbacks, for Northwestern Canada's cold interior. It will use a network of world class observatories to study the detailed connections among changing climate, ecosystems and water in the permafrost regions of the Sub-arctic, the Boreal Forest, the Western Cordillera, and the Prairies. Specifically, the network will: 1. Document and evaluate observed Earth system change, including hydrological, ecological, cryospheric and atmospheric components over a range of scales from local observatories to biome and regional scales; 2. Improve understanding and diagnosis of local-scale change by developing new and integrative knowledge of Earth system processes, incorporating these processes into a suite of process-based integrative

  13. Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Colorado River ends its 2330 km journey in the Gulf of Mexico in Baja California. The heavy use of the river as an irrigation source for the Imperial Valley has dessicated the lower course of the river in Mexico such that it no longer consistently reaches the sea. Prior to the mid 20th century, the Colorado River Delta provided a rich estuarine marshland that is now essentially desiccated, but nonetheless is an important ecological resource.

    The image was acquired May 29, 2006, covers an area of 44.3 x 57.5 km, and is located at 32.1 degrees north latitude, 115.1 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  14. The influence of the Mackenzie River plume on distribution and diversity of marine larval fish assemblages on the Canadian Beaufort Shelf

    NASA Astrophysics Data System (ADS)

    Wong, Sally; Walkusz, Wojciech; Hanson, Mark; Papst, Michael H.

    2013-11-01

    In the Beaufort Sea, freshwater input from the Mackenzie River creates a relatively warm and turbid plume across the coastal shelf region. To determine the influence of this plume on marine larval fish abundance, distribution, and assemblages, we sampled larval fish during July and August of 2007 using 500 μm bongo nets on transects across the plume gradient at three sampling stations per transect, along with oceanographic measurements. Three larval fish assemblages were identified within three distinct oceanographic zones: intense plume, diffuse plume and oceanic. The intense plume assemblage was dominated by Saffron cod (Eleginus gracilis) and Pacific herring (Clupea pallasii); the diffuse plume assemblage was dominated by the Pricklebacks (sub-family Lumpeninae); and the oceanic assemblage was dominated by Arctic cod (Boreogadus saida). Even though there were differences in relative abundance of particular species among these areas, no significant differences in total abundances of larval fish were found.

  15. Zircon (U-Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Powell, Jeremy; Schneider, David; Stockli, Daniel; Fallas, Karen

    2016-03-01

    Sedimentary strata of the Neoproterozoic Mackenzie Mountains Supergroup (MMSG) and Windermere Supergroup (WSG) occupy the cores of anticlines in the Mackenzie Mountains of the Canadian Cordilleran Foreland Belt. Stratigraphic and structural evidence suggest that these rocks have undergone several episodes of burial and unroofing relatively intact. We report single-grain detrital muscovite 40Ar/39Ar and zircon (U-Th)/He (ZHe) data from a suite of samples across the fold-thrust belt and the Neoproterozoic stratigraphic record. The strata have not reached high enough temperatures to reset the muscovite 40Ar/39Ar system, and instead our detrital muscovite data refine Tonian-Cryogenian depositional ages. Single-crystal ZHe dates range from 432 ± 35 to 46 ± 4 Ma, indicating that MMSG and WSG strata have not been heated sufficiently to fully reset the ZHe system. These factors make the Neoproterozoic strata an attractive natural laboratory to test the utility of the zircon radiation damage and annealing model on the quantification of thermal histories from detrital zircon populations that have accumulated radiation damage over long geologic timescales. Thermal modeling reveals that (1) a substantial sedimentary package was deposited following the Devonian and removed during Permo-Triassic cooling, and (2) the Cordilleran deformation front propagated through the study area from the Albian to the Paleocene, with a moderate increase in cooling rates between 75-67 Ma in the southwest and 60-55 Ma at the deformation front. Ultimately, relationships between radiation damage and helium diffusion kinetics in zircon explain substantial ZHe date dispersion and elucidate the temperature-time history of the northern Canadian Cordillera.

  16. Artificial delta growth

    NASA Astrophysics Data System (ADS)

    Mikeš, Daniel

    2010-05-01

    A deltaic sedimentary system has a point source; sediment is carried over the delta plain by distributary channels away from the point source and deposited at the delta front by distributary mouth bars. The established methods to describe such a sedimentary system are "bedding analysis", "facies analysis", and "basin analysis". We shall call the ambient conditions "input" and the rock record "output". There exist a number of methods to deduce input from output, e.g. "Sequence stratigraphy" (a.o. Vail et al. 1977, Catuneanu et al. 2009), "Shoreline trajectory" (a.o. Helland-Hansen & Martinsen 1996, Helland-Hansen & Hampson 2009) on the one hand and the complex use of established techniques on the other (a.o. Miall & Miall 2001, Miall & Miall 2002). None of these deductive methods seems to be sufficient. I claim that the common errors in all these attempts are the following: (1) a sedimentary system is four-dimensional (3+1) and a lesser dimensional analysis is insufficient; (2) a sedimentary system is complex and any empirical/deductive analysis is non-unique. The proper approach to the problem is therefore the theoretical/inductive analysis. To that end we performed six scenarios of a scaled version of a passive margin delta in a flume tank. The scenarios have identical stepwise tectonic subsidence and semi-cyclic sealevel, but different supply curves, i.e. supply is: constant, highly-frequent, proportional to sealevel, inversely proportional to sealevel, lagging to sealevel, ahead of sealevel. The preliminary results are indicative. Lobe-switching occurs frequently and hence locally sedimentation occurs shortly and hiatuses are substantial; therefore events in 2D (+1) cross-sections don't correlate temporally. The number of sedimentary cycles disequals the number of sealevel cycles. Lobe-switching and stepwise tectonic subsidence cause onlap/transgression. Erosional unconformities are local diachronous events, whereas maximum flooding surfaces are regional

  17. Delta spots and great flares

    NASA Technical Reports Server (NTRS)

    Zirin, Harold; Liggett, Margaret A.

    1987-01-01

    The development of delta spots and the great flares they produce are reviewed based on 18 years of observations. Delta groups are found to develop in three ways: (1) by the eruption of a single complex active region formed below the surface; (2) by the eruption of large satellite spots near a large older spot; and (3) by the collision of spots of opposite polarity from different dipoles. It is shown that the present sample of 21 delta spots never separate once they lock together, and that the driving force for the shear is spot motion. Indicators for the prediction of the occurrence of great flares are identified.

  18. Delta-9 desaturase from sharpshooters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomic analyses of several leafhoppers identified the first leafhopper delta-9 desaturase. Identification of important gene transcripts within insect pests permits them to be targeted with RNA interference, RNAi, strategies. The glassy-winged sharpshooter, GWSS (Hemiptera: Cicadellidae; Homalodis...

  19. Supersonic aerodynamics of delta wings

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.

    1988-01-01

    Through the empirical correlation of experimental data and theoretical analysis, a set of graphs has been developed which summarize the inviscid aerodynamics of delta wings at supersonic speeds. The various graphs which detail the aerodynamic performance of delta wings at both zero-lift and lifting conditions were then employed to define a preliminary wing design approach in which both the low-lift and high-lift design criteria were combined to define a feasible design space.

  20. Highly siderophile element behaviour during flood basalt genesis and evidence for melts from intrusive chromitite formation in the Mackenzie large igneous province

    NASA Astrophysics Data System (ADS)

    Day, James M. D.; Pearson, D. Graham; Hulbert, Larry J.

    2013-12-01

    The 1.27 Ga Coppermine continental flood basalt (CFB) province in northern Canada represents the extrusive manifestation of the 2.7 Mkm2 Mackenzie large igneous province (LIP) that includes the Mackenzie dyke swarm and the Muskox layered intrusion. New Re-Os isotope and highly siderophile element (HSE: Re, Pd, Pt, Ru, Ir, Os) abundance data are reported together with whole-rock major- and trace-element abundances and Nd isotopes to examine the behaviour of the HSE during magmatic differentiation and to place constraints on the extent of crustal interaction with mantle-derived melts. Mineral chemistry and petrography are also reported for an unusual andesite glass flow (CM19; 4.9 wt.% MgO) found in close proximity to newly recognised picrites (> 20 wt.% MgO) in the lowermost stratigraphy of the Coppermine CFB. Compositions of mineral phases in CM19 are similar to the same phases found in Muskox Intrusion chromitites and the melt composition is equivalent to inclusions trapped within Muskox chromites. The apparently conflicting elevated HSE contents (e.g., 3.8 ppb Os) and mantle-like initial 187Os/188Os (γOs = + 2.2), versus stable isotope (δ18O = + 12‰) and lithophile element evidence (εNdi = - 12.8) for extensive crustal contamination, implicate an origin for CM19 as a magma mingling product formed within the Muskox Intrusion during chromitite genesis. Combined with Nd isotope data that places the feeder for lower Coppermine CFB picrites and basalts within the Muskox Intrusion, this result provides compelling evidence for direct processing of some CFB within upper-crustal magma chambers. The Coppermine CFB defines a 187Re-187Os isochron with an age of 1263 + 16/- 20 Ma and initial γOs = + 2.2 ± 0.8. The initial Os isotope composition for the Coppermine CFB is slightly higher than the near-primitive-mantle initial 187Os/188Os for the Muskox Intrusion (γOs = + 1.2 ± 0.3). This result is interpreted to reflect greater crustal contamination in extrusive CFB

  1. The DELTA Synchrotron Light Interferometer

    SciTech Connect

    Berges, U.

    2004-05-12

    Synchrotron radiation sources like DELTA, the Dortmund Electron Accelerator, a third generation synchrotron light source, need an optical monitoring system to measure the beam size at different points of the ring with high resolution and accuracy. These measurements also allow an investigation of the emittance of the storage ring, an important working parameter for the efficiency of working beamlines with experiments using the synchrotron radiation. The resolution limits of the different types of optical synchrotron light monitors at DELTA are investigated. The minimum measurable beamsize with the normal synchrotron light monitor using visible light at DELTA is about 80 {mu}m. Due to this a synchrotron light interferometer was built up and tested at DELTA. The interferometer uses the same beamline in the visible range. The minimum measurable beamsize is with about 8 {mu}m one order of magnitude smaller. This resolution is sufficient for the expected small vertical beamsizes at DELTA. The electron beamsize and emittance were measured with both systems at different electron beam energies of the storage ring. The theoretical values of the present optics are smaller than the measured emittance. So possible reasons for beam movements are investigated.

  2. Understanding Nearshore Processes Of a Large Arctic Delta Using Combined Seabed Mapping, In Situ Observations, Remote Sensing and Modeling

    NASA Astrophysics Data System (ADS)

    Solomon, S. M.; Couture, N. J.; Forbes, D. L.; Hoque, A.; Jenner, K. A.; Lintern, G.; Mulligan, R. P.; Perrie, W. A.; Stevens, C. W.; Toulany, B.; Whalen, D.

    2009-12-01

    The Mackenzie River Delta and the adjacent continental shelf in the southeastern Beaufort Sea are known to host significant quantities of hydrocarbons. Recent environmental reviews of proposed hydrocarbon development have highlighted the need for a better understanding of the processes that control sediment transport and coastal stability. Over the past several years field surveys have been undertaken in winter, spring and summer to acquire data on seabed morphology, sediment properties, sea ice, river-ocean interaction and nearshore oceanography. These data are being used to improve conceptual models of nearshore processes and to develop and validate numerical models of waves, circulation and sediment transport. The timing and location of sediment erosion, transport and deposition is complex, driven by a combination of open water season storms and spring floods. Unlike temperate counterparts, the interaction between the Mackenzie River and the Beaufort Sea during spring freshet is mediated by the presence of ice cover. Increasing discharge exceeds the under-ice flow capacity leading to flooding of the ice surface, followed by vortex drainage through the ice and scour of the seabed below (“strudel” drainage and scour). During winter months, nearshore circulation slows beneath a thickening ice canopy. Recent surveys have shown that the low gradient inner shelf is composed of extensive shoals where ice freezes to the seabed and intervening zones which are slightly deeper than the ice is thick. The duration of ice contact with the bed determines the thermal characteristics of the seabed. Analysis of cores shows that the silts comprising the shoals are up to 6 m thick. The predominantly well sorted and cross-laminated nature of the silts at the top of the cores suggests an active delta front environment. Measurements of waves, currents, conductivity, temperature and sediment concentration during spring and late summer have been acquired. During moderate August

  3. Soil Organic Carbon Stocks in Arctic Deltaic Sediments: Investigations in the Lena River Delta.

    NASA Astrophysics Data System (ADS)

    Zubrzycki, S.; Kutzbach, L.; Desyatkin, A.; Pfeiffer, E.-M.

    2012-04-01

    The soil organic carbon stock (SSOC) of deltaic sediments in arctic permafrost regions is known to be significant but is insufficiently investigated so far. Previous SSOC studies were conducted mainly in the comparatively well studied Mackenzie River Delta (area: 13,000 km2) in Canada. The few studies from other arctic delta regions report only the gravimetric carbon (C) contents and are limited to the active layer depth at the time of sampling. Since C deposits in permafrost regions are likely to become a future C source, more detailed investigations of the presently frozen likely carbon-rich sediment and soil layers in other arctic delta regions are of importance. Our investigations were performed on Samoylov Island in the southern-central part of the Lena River Delta (32,000 km2) which is the largest arctic delta and the fifth largest delta worldwide. Samoylov Island is representative for the Lena River Delta's first terrace and the active floodplains. Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE) auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 37) distributed over all known soil and vegetation units. These cores are analyzed for bulk contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC including the rarely investigated currently permanently frozen layers up to 1 m depth on Samoylov Island. Our study provides evidence for high SSOC for a depth of 1 m for the investigated area ranging between 6 kg m2 and 54 kg m2. Considering the spatial extent of different soil units on the two geomorphological units of Samoylov Island, the area-weighted average SSOC were 31 kg m2 (n = 31) for the first terrace and 15 kg m2 (n = 6) for the active floodplain. For the correspondent soil units of Turbels and Orthels in circumpolar permafrost regions, Tarnocai et al. 2009 reported a mean SSOC of 27 kg m2 (min: 0.1 kg m2, max: 126 kg m2) for a depth of 1 m. For up

  4. The Mackenzie River magnetic anomaly, Yukon and Northwest Territories, Canada-Evidence for Early Proterozoic magmatic arc crust at the edge of the North American craton

    USGS Publications Warehouse

    Pilkington, M.; Saltus, R.W.

    2009-01-01

    We characterize the nature of the source of the high-amplitude, long-wavelength, Mackenzie River magnetic anomaly (MRA), Yukon and Northwest Territories, Canada, based on magnetic field data collected at three different altitudes: 300??m, 3.5??km and 400??km. The MRA is the largest amplitude (13??nT) satellite magnetic anomaly over Canada. Within the extent of the MRA, source depth estimates (8-12??km) from Euler deconvolution of low-altitude aeromagnetic data show coincidence with basement depths interpreted from reflection seismic data. Inversion of high-altitude (3.5??km) aeromagnetic data produces an average magnetization of 2.5??A/m within a 15- to 35-km deep layer, a value typical of magmatic arc complexes. Early Proterozoic magmatic arc rocks have been sampled to the southeast of the MRA, within the Fort Simpson magnetic anomaly. The MRA is one of several broad-scale magnetic highs that occur along the inboard margin of the Cordillera in Canada and Alaska, which are coincident with geometric changes in the thrust front transition from the mobile belt to stable cratonic North America. The inferred early Proterozoic magmatic arc complex along the western edge of the North American craton likely influenced later tectonic evolution, by acting as a buttress along the inboard margin of the Cordilleran fold-and-thrust belt. Crown Copyright ?? 2008.

  5. Delta launch vehicle inertial guidance system (DIGS)

    NASA Technical Reports Server (NTRS)

    Duck, K. I.

    1973-01-01

    The Delta inertial guidance system, part of the Delta launch vehicle improvement effort, has been flown on three launches and was found to perform as expected for a variety of mission profiles and vehicle configurations.

  6. Delta Revival: Restoring a California Ecosystem

    USGS Publications Warehouse

    U.S. Geological Survey; California Bay Delta Authority

    2003-01-01

    'Delta Revival: Restoring a California Ecosystem' shows scientists from many disciplines working together to guide the unprecendented restoration of the Sacramento- San Joaquin Delta east of San Francisco Bay.

  7. Spongeplant Spreading in the Delta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive, exotic aquatic plants impact a range of important economic and ecological functions in the Sacramento-San Joaquin Delta of California, and the state now spends over $5 million to control water hyacinth and Brazilian waterweed. In 2007, a new exotic floating plant South American Spongeplan...

  8. Delta-ALA urine test

    MedlinePlus

    ... increased level of urinary delta-ALA may indicate: Lead poisoning Porphyria (several types) A decreased level may occur ... A.M. Editorial team. Related MedlinePlus Health Topics Lead Poisoning Porphyria Browse the Encyclopedia A.D.A.M., ...

  9. Delta launch vehicle accident investigation

    NASA Astrophysics Data System (ADS)

    1986-03-01

    The text of the testimony given by several witnesses during the House hearings on the Delta launch vehicle accident of May 3, 1986 is given. Pre-launch procedures, failure analysis, the possibility of sabotage, and design and testing are among the topics discussed.

  10. N-{Delta} weak transition

    SciTech Connect

    Graczyk, Krzysztof M.

    2011-11-23

    A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-{Delta}(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.

  11. Phytoplankton fuels Delta food web

    USGS Publications Warehouse

    Jassby, Alan D.; Cloern, James E.; Muller-Solger, A. B.

    2003-01-01

    Populations of certain fishes and invertebrates in the Sacramento-San Joaquin Delta have declined in abundance in recent decades and there is evidence that food supply is partly responsible. While many sources of organic matter in the Delta could be supporting fish populations indirectly through the food web (including aquatic vegetation and decaying organic matter from agricultural drainage), a careful accounting shows that phytoplankton is the dominant food source. Phytoplankton, communities of microscopic free-floating algae, are the most important food source on a Delta-wide scale when both food quantity and quality are taken into account. These microscopic algae have declined since the late 1960s. Fertilizer and pesticide runoff do not appear to be playing a direct role in long-term phytoplankton changes; rather, species invasions, increasing water transparency and fluctuations in water transport are responsible. Although the potential toxicity of herbicides and pesticides to plank- ton in the Delta is well documented, the ecological significance remains speculative. Nutrient inputs from agricultural runoff at current levels, in combination with increasing transparency, could result in harmful al- gal blooms. 

  12. Revisiting double Dirac delta potential

    NASA Astrophysics Data System (ADS)

    Ahmed, Zafar; Kumar, Sachin; Sharma, Mayank; Sharma, Vibhu

    2016-07-01

    We study a general double Dirac delta potential to show that this is the simplest yet still versatile solvable potential to introduce double wells, avoided crossings, resonances and perfect transmission (T = 1). Perfect transmission energies turn out to be the critical property of symmetric and anti-symmetric cases wherein these discrete energies are found to correspond to the eigenvalues of a Dirac delta potential placed symmetrically between two rigid walls. For well(s) or barrier(s), perfect transmission (or zero reflectivity, R(E)) at energy E=0 is non-intuitive. However, this has been found earlier and called the ‘threshold anomaly’. Here we show that it is a critical phenomenon and we can have 0≤slant R(0)\\lt 1 when the parameters of the double delta potential satisfy an interesting condition. We also invoke a zero-energy and zero curvature eigenstate (\\psi (x)={Ax}+B) of the delta well between two symmetric rigid walls for R(0)=0. We resolve that the resonant energies and the perfect transmission energies are different and they arise differently.

  13. Maintenance of large deltas through channelization

    NASA Astrophysics Data System (ADS)

    Giosan, L.; Constatinescu, S.; Filip, F.

    2013-12-01

    A new paradigm for delta restoration is currently taking shape using primarily Mississippi delta examples. Here we propose an alternative for delta maintenance primarily envisioned for wave-influenced deltas based on Danube delta experiences. Over the last half century, while the total sediment load of the Danube dramatically decreased due to dam construction on tributaries and its mainstem, a grand experiment was inadvertently run in the Danube delta: the construction of a dense network of canals, which almost tripled the water discharge toward the interior of the delta plain. We use core-based and chart-based sedimentation rates and patterns to explore the delta transition from the natural to an anthropogenic regime, to understand the effects of far-field damming and near-field channelization, and to construct a conceptual model for delta development as a function sediment partition between the delta plain and the delta coastal fringe. We show that sediment fluxes increased to the delta plain due to channelization, counteracting sea level rise. In turn, the delta coastal fringe was most impacted by the Danube's sediment load collapse. Furthermore, we show that morphodynamic feedbacks at the river mouth are crucial in trapping sediment near the coast and constructing wave-dominated deltas or lobes or delaying their destruction. As a general conclusion, we suggest that increased channelization that mimics and enhances natural processes may provide a simple solution for keeping delta plains above sea level and that abandonment of wave-dominated lobes may be the most long term efficient solution for protecting the internal fluvial regions of deltas and provide new coastal growth downcoast.

  14. Assessment of Delta Nitrogen Losses (Delta NL) at the Field Level

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We defined a new concept of field-level delta nitrogen (N) losses (Delta NL) as a comparison between management scenarios. We defined delta nitrogen losses (Delta NL) as a function of improved N use efficiencies of field management scenarios that reduce the average N inputs and/or modify other manag...

  15. The calculation of T{sub {delta}} and V{sub {delta}} in austenitic steel

    SciTech Connect

    Dai Qixun; Yang Ruzeng

    1997-03-01

    The relation between the {gamma}/{gamma} + {delta} boundary temperature, T{sub {delta}}, of austenitic steels and the equivalent weights, [Cr] and [Ni], has been studied, as has the law of variation of the {delta} phase volume, V{sub {delta}}, with temperature. With the aid of a computer, the following regression expressions have been derived from the experimental results: T{sub {delta}} ({degree}C) =- T{sub 4} {minus} 21.2[Cr] + 15.8[Ni] {minus} 223; V{sub {delta}} (%) = 0.715 exp [0.015(T {minus} T{sub {delta}})]. Satisfactory results have been obtained by using these regression expressions.

  16. The Changing Cold Regions Network: Improving the Understanding and Prediction of Changing Land, Water, and Climate in the Mackenzie and Saskatchewan River Basins, Canada

    NASA Astrophysics Data System (ADS)

    DeBeer, C. M.; Wheater, H. S.; Chun, K. P.; Shook, K.; Whitfield, P. H.

    2014-12-01

    Within the cold interior of western and northern Canada, rapid and widespread environmental changes are taking place, which are of serious concern for society and have a range of implications from local to regional and global scales. From a scientific standpoint there is an urgent need to understand the changes and develop improved diagnostic and predictive modelling tools to deal with the uncertainty faced in the future. The Changing Cold Regions Network (CCRN) is a research consortium of over 50 Canadian university and government scientists and international researchers aimed at addressing these issues within the geographic domain of the Mackenzie and Saskatchewan River Basins. CCRN's primary focus is to integrate existing and new experimental data with modelling and remote sensing products to understand, diagnose and predict changing land, water and climate, and their interactions and feedbacks. To support these activities, the network utilizes a suite of 14 world-class water, ecosystem, cryosphere and climate (WECC) observatories across this region that provide exceptional opportunities to observe change, investigate processes and their dynamics, and develop and test environmental models. This talk will briefly describe the CCRN thematic components and WECC observatories, and will then describe some of the observed environmental changes and their linkages across the northern and mountainous parts of the network study domain. In particular, this will include changes in permafrost, terrestrial vegetation, snowcover, glaciers, and river discharge in relation to observed climatic changes across the region. The observations draw on a wide range of literature sources and statistical analyses of federal and provincial regional monitoring network data, while more detailed observations at some of the WECC observatories help to show how these regional changes are manifested at local scales and vice versa. A coordinated special observation and analysis period across all

  17. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J.-F.

    2012-12-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea, Canadian Arctic Ocean, with a particular focus on free-living vs. particle-attached communities. Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between particle-attached (PA) and free-living (FL) bacterial communities in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (proxy of DOC and CDOM), suspended particles, amino acids and chlorophyll a. 16S rRNA genes pyrosequencing of selected samples confirmed these significant differences from river to sea and also between PA and FL fractions only in open sea samples, and PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, the coast and river samples, both PA and FL fractions, were dominated by Betaproteobacteria, Alphaproteobacteria and Actinobacteria. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a~basis to predict further changes in bacterial communities should climate change lead to further

  18. Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J. F.

    2013-04-01

    We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean, with a particular focus on free-living (FL) vs. particle-attached (PA) communities. Capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Pyrosequencing of 16S rRNA genes from selected samples confirmed significant differences between river, coastal and sea samples. The PA fraction was only different (15.7% similarity) from the FL one in the open sea sample. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, for the coast and river samples and both PA and FL fractions, Betaproteobacteria, Alphaproteobacteria and Actinobacteria were dominant. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also

  19. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    SciTech Connect

    Zhang, H.Y.; Zhang, S.H.; Cheng, M.; Li, Z.X.

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  20. The delta (delta) gap: an approach to mixed acid-base disorders.

    PubMed

    Wrenn, K

    1990-11-01

    The anion gap (AG) is a helpful, yet underused, clinical tool. Not only does the presence of a high AG suggest a certain differential, but knowledge of the relationship between the rise in AG (delta AG) and the fall in bicarbonate (delta HCO3) is important in understanding mixed acid-based disorders. Simple arithmetic converts this relationship into a numerical value, the delta gap (delta gap). The delta gap = delta AG - delta HCO3. If the delta gap is significantly positive (greater than +6), a metabolic alkalosis is usually present because the rise in AG is more than the fall in HCO3. Conversely, if the delta gap is significantly negative (less than -6), then a hyperchloremic acidosis is usually present because the rise in AG is less than the fall in HCO3. Familarity with the relationship between the changes in AG and HCO3 can be useful in unmasking occult metabolic disorders. PMID:2240729

  1. Future Deltas Utrecht University research focus area: towards sustainable management of sinking deltas

    NASA Astrophysics Data System (ADS)

    Stouthamer, E.; van Asselen, S.

    2015-11-01

    Deltas are increasingly under pressure from human impact and climate change. To deal with these pressures that threat future delta functioning, we need to understand interactions between physical, biological, chemical and social processes in deltas. This requires an integrated approach, in which knowledge on natural system functioning is combined with knowledge on spatial planning, land and water governance and legislative frameworks. In the research focus area Future Deltas of Utrecht University an interdisciplinary team from different research groups therefore works together. This allows developing integrated sustainable and resilient delta management strategies, which is urgently needed to prevent loss of vital delta services.

  2. Using open hole and cased-hole resistivity logs to monitor gas hydrate dissociation during a thermal test in the mallik 5L-38 research well, Mackenzie Delta, Canada

    USGS Publications Warehouse

    Anderson, B.I.; Collett, T.S.; Lewis, R.E.; Dubourg, I.

    2008-01-01

    Gas hydrates, which are naturally occurring ice-like combinations of gas and water, have the potential to provide vast amounts of natural gas from the world's oceans and polar regions. However, producing gas economically from hydrates entails major technical challenges. Proposed recovery methods such as dissociating or melting gas hydrates by heating or depressurization are currently being tested. One such test was conducted in northern Canada by the partners in the Mallik 2002 Gas Hydrate Production Research Well Program. This paper describes how resistivity logs were used to determine the size of the annular region of gas hydrate dissociation that occurred around the wellbore during the thermal test in the Mallik 5L-38 well. An open-hole logging suite, run prior to the thermal test, included array induction, array laterolog, nuclear magnetic resonance and 1.1-GHz electromagnetic propagation logs. The reservoir saturation tool was run both before and after the thermal test to monitor formation changes. A cased-hole formation resistivity log was run after the test.Baseline resistivity values in each formation layer (Rt) were established from the deep laterolog data. The resistivity in the region of gas hydrate dissociation near the wellbore (Rxo) was determined from electromagnetic propagation and reservoir saturation tool measurements. The radius of hydrate dissociation as a function of depth was then determined by means of iterative forward modeling of cased-hole formation resistivity tool response. The solution was obtained by varying the modeled dissociation radius until the modeled log overlaid the field log. Pretest gas hydrate production computer simulations had predicted that dissociation would take place at a uniform radius over the 13-ft test interval. However, the post-test resistivity modeling showed that this was not the case. The resistivity-derived dissociation radius was greatest near the outlet of the pipe that circulated hot water in the wellbore, where the highest temperatures were recorded. The radius was smallest near the center of the test interval, where a conglomerate section with low values of porosity and permeability inhibited dissociation. The free gas volume calculated from the resistivity-derived dissociation radii yielded a value within 20 per cent of surface gauge measurements. These results show that the inversion of resistivity measurements holds promise for use in future gas hydrate monitoring. ?? 2008 Society of Petrophysicists and Well Log Analysts. All rights reserved.

  3. COMMD1 regulates the delta epithelial sodium channel ({delta}ENaC) through trafficking and ubiquitination

    SciTech Connect

    Chang, Tina; Ke, Ying; Ly, Kevin; McDonald, Fiona J.

    2011-08-05

    Highlights: {yields} The COMM domain of COMMD1 mediates binding to {delta}ENaC. {yields} COMMD1 reduces the cell surface population of {delta}ENaC. {yields} COMMD1 increases the population of {delta}ENaC-ubiquitin. {yields} Both endogenous and transfected {delta}ENaC localize with COMMD1 and transferrin suggesting they are located in early/recycling endosomes. -- Abstract: The delta subunit of the epithelial sodium channel ({delta}ENaC) is a member of the ENaC/degenerin family of ion channels. {delta}ENaC is distinct from the related {alpha}-, {beta}- and {gamma}ENaC subunits, known for their role in sodium homeostasis and blood pressure control, as {delta}ENaC is expressed in brain neurons and activated by external protons. COMMD1 (copper metabolism Murr1 domain 1) was previously found to associate with and downregulate {delta}ENaC activity. Here, we show that COMMD1 interacts with {delta}ENaC through its COMM domain. Co-expression of {delta}ENaC with COMMD1 significantly reduced {delta}ENaC surface expression, and led to an increase in {delta}ENaC ubiquitination. Immunocytochemical and confocal microscopy studies show that COMMD1 promoted localization of {delta}ENaC to the early/recycling endosomal pool where the two proteins were localized together. These results suggest that COMMD1 downregulates {delta}ENaC activity by reducing {delta}ENaC surface expression through promoting internalization of surface {delta}ENaC to an intracellular recycling pool, possibly via enhanced ubiquitination.

  4. Navigational Use of Cassini Delta V Telemetry

    NASA Technical Reports Server (NTRS)

    Roth, Duane C.; Antreasian, Peter G.; Ardalan, Shadan M.; Criddle, Kevin E.; Goodson, Troy; Ionasescu, Rodica; Jones, Jeremy B.; Parcher, Daniel W.; Pelletier, Frederic J.; Thompson, Paul F.; Vaughan, Andrew T.

    2008-01-01

    Telemetry data are used to improve navigation of the Saturn orbiting Cassini spacecraft. Thrust induced delta V's are computed on-board the spacecraft, recorded in telemetry, and downlinked to Earth. This paper discusses how and why the Cassini Navigation team utilizes spacecraft delta V telemetry. Operational changes making this information attractive to the Navigation Team will be briefly discussed, as will spacecraft hardware and software algorithms responsible for the on-board computation. An analysis of past delta V telemetry, providing calibrations and accuracies that can be applied to the estimation of future delta V activity, is described.

  5. Comments on the slip factor and the relation Delta phi = -h Delta theta

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2009-09-01

    The definition of the slip factor can be obtained from the phase equation. However, a derivation using the relation {Delta}{phi} = -h{Delta}{theta} leads to a different slip-factor definition. This apparent paradox is examined in detail and resolved. Here {Delta}{phi} is the rf phase difference and {Delta}{theta} is the azimuthal phase difference around the accelerator ring between an off-momentum particle and the synchronous particle, while h is the rf harmonic.

  6. Resilience of Arctic Permafrost Carbon in Mackenzie River Basin: An Incubation Experiment to Observe Priming Potentials and Biodegradability of Arctic Permafrost Peatlands

    NASA Astrophysics Data System (ADS)

    Hedgpeth, A.; Beilman, D.; Crow, S. E.

    2015-12-01

    Arctic permafrost zones cover 25% of the Northern Hemisphere and hold 1672Pg of soil carbon (C) with 277Pg in Arctic permafrost peatlands, which is 1/3 of the CO2 in the atmosphere. This currently protected C is a potential source for increased emissions in a warmer climate. Longer growing seasons resulting in increased plant productivity above and below ground may create new labile C inputs with the potential to affect mineralization of previously stable SOM, known as the priming effect. This study examined the response of soil respiration to labile substrate addition in carbon-rich (42-48 %C) permafrost peatland soils along a N-S transect in the central Mackenzie River Basin (69.2-62.6°N). Active layer and near surface soils (surface Δ14C values > -140.0) were collected from four sites between -10.5 and -5.2 MAT. Soils were spiked with 0.5 mg D-glucose g-1soil, and incubated at 10°C for 23 days to determine potential, short term (i.e., apparent) priming effects. On average glucose addition increased respiration in all samples. One site showed priming evidence in active layer soils despite one-way ANOVA not illustrating statistically significant differences between control and treated final cumulative CO2. Apparent priming effects were seen in two near surface permafrost samples, however cumulative increases in CO2 were not identified as significant. When all results from all sites and depths were considered, the addition of glucose showed no significant effect on total CO2 production relative to controls (p=0.957), suggesting that these sites may be resilient to increased inputs in that little priming evidence was observed. To test the idea that the soils that showed priming effects are of poorer quality, we conducted an additional incubation experiment to explore the biodegradability of these permafrost peatland soils. Soils from these four sites were inoculated and incubated for 17 days. The two sites with observed priming showed the highest biodegradability

  7. Setting the renormalization scale in perturbative QCD: Comparisons of the principle of maximum conformality with the sequential extended Brodsky-Lepage-Mackenzie approach

    NASA Astrophysics Data System (ADS)

    Ma, Hong-Hao; Wu, Xing-Gang; Ma, Yang; Brodsky, Stanley J.; Mojaza, Matin

    2015-05-01

    A key problem in making precise perturbative QCD (pQCD) predictions is how to set the renormalization scale of the running coupling unambiguously at each finite order. The elimination of the uncertainty in setting the renormalization scale in pQCD will greatly increase the precision of collider tests of the Standard Model and the sensitivity to new phenomena. Renormalization group invariance requires that predictions for observables must also be independent on the choice of the renormalization scheme. The well-known Brodsky-Lepage-Mackenzie (BLM) approach cannot be easily extended beyond next-to-next-to-leading order of pQCD. Several suggestions have been proposed to extend the BLM approach to all orders. In this paper we discuss two distinct methods. One is based on the "Principle of Maximum Conformality" (PMC), which provides a systematic all-orders method to eliminate the scale and scheme ambiguities of pQCD. The PMC extends the BLM procedure to all orders using renormalization group methods; as an outcome, it significantly improves the pQCD convergence by eliminating renormalon divergences. An alternative method is the "sequential extended BLM" (seBLM) approach, which has been primarily designed to improve the convergence of pQCD series. The seBLM, as originally proposed, introduces auxiliary fields and follows the pattern of the β0 -expansion to fix the renormalization scale. However, the seBLM requires a recomputation of pQCD amplitudes including the auxiliary fields; due to the limited availability of calculations using these auxiliary fields, the seBLM has only been applied to a few processes at low orders. In order to avoid the complications of adding extra fields, we propose a modified version of seBLM which allows us to apply this method to higher orders. We then perform detailed numerical comparisons of the two alternative scale-setting approaches by investigating their predictions for the annihilation cross section ratio Re+e- at four-loop order in pQCD.

  8. Setting the renormalization scale in pQCD: Comparisons of the principle of maximum conformality with the sequential extended Brodsky-Lepage-Mackenzie approach

    SciTech Connect

    Ma, Hong -Hao; Wu, Xing -Gang; Ma, Yang; Brodsky, Stanley J.; Mojaza, Matin

    2015-05-26

    A key problem in making precise perturbative QCD (pQCD) predictions is how to set the renormalization scale of the running coupling unambiguously at each finite order. The elimination of the uncertainty in setting the renormalization scale in pQCD will greatly increase the precision of collider tests of the Standard Model and the sensitivity to new phenomena. Renormalization group invariance requires that predictions for observables must also be independent on the choice of the renormalization scheme. The well-known Brodsky-Lepage-Mackenzie (BLM) approach cannot be easily extended beyond next-to-next-to-leading order of pQCD. Several suggestions have been proposed to extend the BLM approach to all orders. In this paper we discuss two distinct methods. One is based on the “Principle of Maximum Conformality” (PMC), which provides a systematic all-orders method to eliminate the scale and scheme ambiguities of pQCD. The PMC extends the BLM procedure to all orders using renormalization group methods; as an outcome, it significantly improves the pQCD convergence by eliminating renormalon divergences. An alternative method is the “sequential extended BLM” (seBLM) approach, which has been primarily designed to improve the convergence of pQCD series. The seBLM, as originally proposed, introduces auxiliary fields and follows the pattern of the β0-expansion to fix the renormalization scale. However, the seBLM requires a recomputation of pQCD amplitudes including the auxiliary fields; due to the limited availability of calculations using these auxiliary fields, the seBLM has only been applied to a few processes at low orders. In order to avoid the complications of adding extra fields, we propose a modified version of seBLM which allows us to apply this method to higher orders. As a result, we then perform detailed numerical comparisons of the two alternative scale-setting approaches by investigating their predictions for the annihilation cross section ratio R

  9. Determination de l'humidite du sol dans le Bassin Versant du Mackenzie a partir des donnees satellitaires AMSR-E

    NASA Astrophysics Data System (ADS)

    Chaouch, Naira

    The present project focuses on the retrieval of surface soil moisture using multi-satellite data from microwave, visible and infrared measurements over the Mackenzie River Basin, a large northern basin located in Canada. The work is subdivided in two major steps. The first step aims to estimate soil moisture and to monitor its change using AMSR-E 6.9 GHz passive microwave data. To reach the objective of this work, a major issue to be resolved is the lack of in situ measurements. Therefore, "external" ancillary data were used as a surrogate for in situ data in retrieving soil moisture by inverting a microwave radiative transfer model. Based on the sensitivity of the emitted microwave signal to soil roughness and to vegetation parameters, a sequential method was applied to calibrate the model. The values of the roughness parameter, vegetation parameters and soil moisture were adjusted iteratively to minimize the sum of the squared difference between the measured AMSR-E brightness temperature and the modelled brightness temperatures using the radiative transfert model. Qualitatively, it was found that the variations of the estimated soil moisture compared well with the soil moisture values imported from the NARR database, and a satisfactory agreement was also obtained between soil moisture estimates and precipitation data. Quantitatively, comparing the estimated soil moisture with the NARR data, a departure is observed for high values of soil moisture. The AMSR-E soil moisture products are underestimated as compared to the NARR estimates. In the second step, an approach is proposed for disaggregating the near surface soil moisture estimated from AMSR-E using combined multispectral and multiresolution remote sensing data. The approach combines the 56 km resolution AMSR-E multipolarization brightness temperatures and the 1 km resolution MODIS Normalized Difference Vegetation index (NDVI) and MODIS surface temperature data. The methodology is based on the correlation

  10. Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

    NASA Astrophysics Data System (ADS)

    Forest, A.; Babin, M.; Stemmann, L.; Picheral, M.; Sampei, M.; Fortier, L.; Gratton, Y.; Bélanger, S.; Devred, E.; Sahlin, J.; Doxaran, D.; Joux, F.; Ortega-Retuerta, E.; Jeffrey, W. H.; Martín, J.; Gasser, B.; Miquel, J. C.

    2012-08-01

    A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here, we combine mooring times-series, ship-based measurements and remote-sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their biophysical determinants in summer. Flux data were obtained with sediment traps and via a regional empirical algorithm applied to particle size-distributions (17 classes from 0.08-4.2 mm) measured by an Underwater Vision Profiler 5. Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e. principal coordinates of neighbor matrices, PCNM), were conducted to partition the variation of POC flux size-classes. Flux variability was explained at 69.5 % by the addition of a linear temporal trend, 7 significant PCNM and 9 biophysical variables. The interaction of all these factors explained 27.8 % of the variability. The first PCNM canonical axis (44.4 % of spatial variance) reflected a shelf-basin gradient controlled by bottom depth and ice concentration (p < 0.01), but a complex assemblage of fine-to-broad scale patterns was also identified. Among biophysical parameters, bacterial production and northeasterly wind (upwelling-favorable) were the two strongest explanatory variables (r2 cum. = 0.37), suggesting that bacteria were associated with sinking material, which was itself partly linked to upwelling-induced productivity. The second most important spatial structure corresponded actually to the two areas where shelf break upwelling is known to occur under easterlies. Copepod biomass was negatively correlated (p < 0.05) with vertical POC fluxes, implying that metazoans played a significant role in the regulation of export fluxes. The low fractal dimension of settling particles (1

  11. BAY DELTA CROSS CHANNEL OPERATIONAL STUDIES

    EPA Science Inventory

    The Delta Cross Channel was constructed in 1953 to deliver low-salinity water from the Sacramento River in Northern California to the South Delta where it is pumped to the San Francisco Bay Area and other parts of the State for public consumption and to the San Joaquin Valley for...

  12. The hepatitis delta virus and its infection

    SciTech Connect

    Rizzeto, M.; Gerin, J.L.; Purcell, R.H.

    1987-01-01

    This book contains over 50 papers. Some of the titles are: Structure and Replication of the Genome of Hepatitis Delta Virus; Clinical Significance of HDV RNA in HDV Disease; HBV DNA in Delta Chronic Carriers; Prevalance of HBV-DNA Among Anti-Hd Positive Patients; and Characterization of LKM/sub 1/ and LKM/sub 2/ Antigens.

  13. Electromagnetic excitation of the Delta(1232) resonance

    SciTech Connect

    V. Pascalutsa; M. Vanderhaeghen; Shin Nan Yang

    2006-09-05

    We review the description of the lowest-energy nucleon excitation--the Delta(1232)-resonance. Much of the recent effort has been focused on the precision measurements of the nucleon to Delta transition by means of electromagnetic probes. We review the results of those measurements and confront them with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice QCD, and QCD-inspired models. Some of the theoretical approaches are reviewed in detail. In particular, we describe the chiral EFT of QCD in the energy domain of the Delta-resonance, and its applications to the electromagnetic nucleon-to-Delta transition (gamma N Delta). We also describe the recent dynamical and unitary-isobar models of pion electroproduction which are extensively used in the extraction of the gamma* N Delta form factors from experiment. Furthermore, we discuss the link of the gamma* N Delta form factors to generalized parton distributions (GPDs), as well as the predictions of perturbative QCD for these transition form factors. The present status of understanding the Delta-resonance properties and the nature of its excitation is summarized.

  14. 27 CFR 9.96 - Mississippi Delta.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Mississippi Delta. 9.96 Section 9.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.96 Mississippi Delta. (a) Name. The name of...

  15. Delta Blues Scholarship and Imperialist Nostalgia.

    ERIC Educational Resources Information Center

    Nye, William P.

    When Delta blues are considered to be "folk music," the genre is inextricably tied to the neocolonial, sharecropping system of cotton production characteristic of the Mississippi Delta region between the Civil War and World War II. "Imperialist nostalgia," then, arises in accounts which pay primary and positive tribute to blues performances…

  16. Delta hepatitis: another concern for dentistry.

    PubMed

    Cottone, J A

    1986-01-01

    Delta hepatitis is a defective virus dependent on hepatitis B virus for replication and transmission. Delta hepatitis infection is becoming more prevalent in the United States, especially in parenteral drug abusers; several outbreaks have occurred. Infection control procedures and the hepatitis B vaccine can protect the dental staff from infection and transmission. PMID:3455994

  17. Delta connected resonant snubber circuit

    DOEpatents

    Lai, J.S.; Peng, F.Z.; Young, R.W. Sr.; Ott, G.W. Jr.

    1998-01-20

    A delta connected, resonant snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the dc supply voltage through the main inverter switches and the auxiliary switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 36 figs.

  18. Delta connected resonant snubber circuit

    DOEpatents

    Lai, Jih-Sheng; Peng, Fang Zheng; Young, Sr., Robert W.; Ott, Jr., George W.

    1998-01-01

    A delta connected, resonant snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the dc supply voltage through the main inverter switches and the auxiliary switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

  19. 78 FR 53127 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ...; ] DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. Date change. SUMMARY: The Delta-Bienville Resource Advisory...

  20. Influence of different organic fertilizers on quality parameters and the delta(15)N, delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of orange fruit (Citrus sinensis L. Osbeck).

    PubMed

    Rapisarda, Paolo; Camin, Federica; Fabroni, Simona; Perini, Matteo; Torrisi, Biagio; Intrigliolo, Francesco

    2010-03-24

    To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the delta(15)N, delta(13)C, delta(2)H, delta (34)S, and delta(18)O values of citrus fruit, a study was performed on the orange fruit cv. 'Valencia late' (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The delta(15)N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, delta(15)N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic fertilizers are of different origins, the natural abundance of (15)N in organic citrus fruit remains higher than in conventional ones. These treatments also did not effect differences in the delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of fruit. PMID:20184327

  1. Particulate Organic Carbon Transport and Burial in the Colville River Delta, Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Bianchi, T. S.; Schreiner, K. M.; Rosenheim, B. E.; Allison, M.

    2013-12-01

    Terrestrial particulate organic carbon (tPOC) delivery to nearshore deltaic regions is an important mechanism of OC storage and burial, and river deltas and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. The Arctic Ocean has the greatest percentage of continental shelf area as a proportion of total ocean basin area of any of the world's oceans, and receives freshwater and sediment from numerous large river systems. Increasing warming in the Arctic is leading to an acceleration of the hydrologic cycle, warming and breakdown of permafrost, and broad shifts in vegetation. All of these changes are likely to affect the delivery and burial of tPOC in nearshore regions. However, to date, most studies of tPOC delivery from North America to the Arctic Ocean have focused on large Arctic rivers like the Mackenzie and Yukon, and a significant portion of the watersheds of those rivers lie in sub-Arctic latitudes, indicating that their tPOC delivery is likely not representative of the high Arctic tundra. This study focuses on tPOC delivery by the Colville River, the largest North American river (in terms of both freshwater delivery and sediment load) with a watershed that does not include sub-Arctic latitudes. Sediment samples from the river delta and nearby Simpson's Lagoon were taken in August of 2010 and subsequently fractionated by density, in order to study the delivery of both discrete and sediment-sorbed tPOC. Samples were analyzed for stable carbon isotopes, bulk radiocarbon, terrestrial biomarkers (including lignin-phenols and non-lignin phenols, specifically those that are indicative of peat input), and aquatic biomarkers (algal pigments), and additionally a subset of the samples were analyzed by ramped pyrolysis-14C. Results show that tPOC delivery is concentrated near the river mouth sourced from coastal plain tundra, with additional delivery of tPOC from peat released into the lagoon from the seaward limit of the

  2. Online high-precision delta(2)H and delta(18)O analysis in water by pyrolysis.

    PubMed

    Lu, Feng H

    2009-10-01

    A method for online simultaneous delta(2)H and delta(18)O analysis in water by high-temperature conversion is presented. Water is injected by using a syringe into a high-temperature carbon reactor and converted into H(2) and CO, which are separated by gas chromatography (GC) and carried by helium to the isotope ratio mass spectrometer for hydrogen and oxygen isotope analysis. A series of experiments was conducted to evaluate several issues such as sample size, temperature and memory effects. The delta(2)H and delta(18)O values in multiple water standards changed consistently as the reactor temperature increased from 1150 to 1480 degrees C. The delta(18)O in water can be measured at a lower temperature (e.g. 1150 degrees C) although the precision was relatively poor at temperatures <1300 degrees C. Memory effects exist for delta(2)H and delta(18)O between two waters, and can be reduced (to <1%) with proper measures. The injection of different amounts of water may affect the isotope ratio results. For example, in contrast to small injections (100 nL or less) from small syringes (e.g. 1.2 microL), large injections (1 microL or more) from larger syringes (e.g. 10 microL) with dilution produced asymmetric peaks and shifts of isotope ratios, e.g. 4 per thousand for delta(2)H and 0.4 per thousand for delta(18)O, probably resulting from isotope fractionation during dilution via the ConFlo interface. This method can be used to analyze nanoliter samples of water (e.g. 30 nL) with good precision of 0.5 per thousand for delta(2)H and 0.1 per thousand for delta(18)O. This is important for geosciences; for instance, fluid inclusions in ancient minerals may be analyzed for delta(2)H and delta(18)O to help understand the formation environments. PMID:19714707

  3. Identifying hazards associated with lava deltas

    USGS Publications Warehouse

    Poland, Michael P.; Orr, Tim R.

    2014-01-01

    Lava deltas, formed where lava enters the ocean and builds a shelf of new land extending from the coastline, represent a significant local hazard, especially on populated ocean island volcanoes. Such structures are unstable and prone to collapse—events that are often accompanied by small explosions that can deposit boulders and cobbles hundreds of meters inland. Explosions that coincide with collapses of the East Lae ‘Apuki lava delta at Kīlauea Volcano, Hawai‘i, during 2005–2007 followed an evolutionary progression mirroring that of the delta itself. A collapse that occurred when the lava–ocean entry was active was associated with a blast of lithic blocks and dispersal of spatter and fine, glassy tephra. Shortly after delta growth ceased, a collapse exposed hot rock to cold ocean water, resulting in an explosion composed entirely of lithic blocks and lapilli. Further collapse of the delta after several months of inactivity, by which time it had cooled significantly, resulted in no recognizable explosion deposit. Seaward displacement and subsidence of the coastline immediately inland of the delta was measured by both satellite and ground-based sensors and occurred at rates of several centimeters per month even after the lava–ocean entry had ceased. The anomalous deformation ended only after complete collapse of the delta. Monitoring of ground deformation may therefore provide an indication of the potential for delta collapse, while the hazard associated with collapse can be inferred from the level of activity, or the time since the last activity, on the delta.

  4. Identifying hazards associated with lava deltas

    NASA Astrophysics Data System (ADS)

    Poland, Michael P.; Orr, Tim R.

    2014-12-01

    Lava deltas, formed where lava enters the ocean and builds a shelf of new land extending from the coastline, represent a significant local hazard, especially on populated ocean island volcanoes. Such structures are unstable and prone to collapse—events that are often accompanied by small explosions that can deposit boulders and cobbles hundreds of meters inland. Explosions that coincide with collapses of the East Lae `Apuki lava delta at Kīlauea Volcano, Hawai`i, during 2005-2007 followed an evolutionary progression mirroring that of the delta itself. A collapse that occurred when the lava-ocean entry was active was associated with a blast of lithic blocks and dispersal of spatter and fine, glassy tephra. Shortly after delta growth ceased, a collapse exposed hot rock to cold ocean water, resulting in an explosion composed entirely of lithic blocks and lapilli. Further collapse of the delta after several months of inactivity, by which time it had cooled significantly, resulted in no recognizable explosion deposit. Seaward displacement and subsidence of the coastline immediately inland of the delta was measured by both satellite and ground-based sensors and occurred at rates of several centimeters per month even after the lava-ocean entry had ceased. The anomalous deformation ended only after complete collapse of the delta. Monitoring of ground deformation may therefore provide an indication of the potential for delta collapse, while the hazard associated with collapse can be inferred from the level of activity, or the time since the last activity, on the delta.

  5. Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

    NASA Astrophysics Data System (ADS)

    Forest, A.; Babin, M.; Stemmann, L.; Picheral, M.; Sampei, M.; Fortier, L.; Gratton, Y.; Bélanger, S.; Devred, E.; Sahlin, J.; Doxaran, D.; Joux, F.; Ortega-Retuerta, E.; Martín, J.; Jeffrey, W. H.; Gasser, B.; Miquel, J. Carlos

    2013-05-01

    A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here we combine mooring times series, ship-based measurements and remote sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their determinants in summer. Flux data were obtained with sediment traps moored around 125 m and via a regional empirical algorithm applied to particle size distributions (17 classes from 0.08-4.2 mm) measured by an Underwater Vision Profiler 5. The low fractal dimension (i.e., porous, fluffy particles) derived from the algorithm (1.26 ± 0.34) and the dominance (~ 77%) of rapidly sinking small aggregates (< 0.5 mm) in total fluxes suggested that settling material was the product of recent aggregation processes between marine detritus, gel-like substances, and ballast minerals. Modeled settling velocity of small and large aggregates was, respectively, higher and lower than in previous studies within which a high fractal dimension (i.e., more compact particles) was consequential of deep-trap collection (~400-1300 m). Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e., principal coordinates of neighbor matrices, PCNM) were conducted to partition the variation of the 17 POC flux size classes. Flux variability was explained at 69.5% by the addition of a temporal trend, 7 significant PCNM, and 9 biophysical variables. The first PCNM canonical axis (44.5% of spatial variance) reflected the total magnitude of POC fluxes through a shelf-basin gradient controlled by bottom depth and sea ice concentration (p < 0.01). The second most important spatial structure (5.0%) corresponded to areas where shelf break upwelling is known to occur under easterlies and where phytoplankton was

  6. N and. delta. resonances: an experimental review

    SciTech Connect

    Kelly, R.L.

    1980-07-01

    Experimental progress in N and ..delta.. resonances since the Oxford baryon conference is reviewed. The review concentrates on hadronic channels, and on developments of the last one or two years. The topics reviewed include the antiproton lifetime; the ..delta../sup + +/ magnetic moment; measurements of ..pi..N elastic and charge-exchange scattering in the ..delta.. region, the eta n threshold region, and the high-mass region; partial wave analyses of ..pi..N ..-->.. ..pi..N; measurements of two-body inelastic ..pi..N scattering; and isobar analyses of ..pi..N ..-->.. ..pi pi..N. 75 references, 3 figures, 4 tables.

  7. Niger Delta play types, Nigeria

    SciTech Connect

    Akinpelu, A.O.

    1995-08-01

    Exploration databases can be more valuable when sorted by play type. Play specific databases provide a system to organize E & P data used in evaluating the range of values of parameters for reserve estimation and risk assessment. It is important both in focusing the knowledge base and in orienting research effort. A play in this context is any unique combination of trap, reservoir and source properties with the right dynamics of migration and preservation that results in hydrocarbon accumulation. This definitions helps us to discriminate the subtle differences found with these accumulation settings. About 20 play types were identified around the Niger Delta oil province in Nigeria. These are grouped into three parts: (1) The proven plays-constituting the bulk of exploration prospects in Nigeria today. (2) The unproven or semi-proven plays usually with some successes recorded in a few tries but where knowledge is still inadequate. (3) The unproven or analogous play concept. These are untested but geologically sound ideas which may or may not have been tried elsewhere. With classification and sub grouping of these play types into specific databases, intrinsic attributes and uniqueness of each of them with respect to the four major risk elements and the eight parameters for reserve estimation can be better understood.

  8. Upper Wilcox Rosita delta system of south Texas: growth-faulted shelf-edge deltas

    SciTech Connect

    Edwards, M.B.

    1981-01-01

    The Rosita delta system, a heretofore unrecognized, major depositional system preserved in the deep upper Wilcox of south Texas, was delineated by detailed correlation of approximately 500 well logs. The Rosita delta system comprises at least three delta complexes, each of which can be traced up to tens of miles along strike and up to approximately 15 mi (24 km) downdip. Basinward, across the growth-fault zone, each delta complex thickens from about 600 ft (180 m) to more than 3000 ft (900 m). The growth faults were activated by progradation of deltas over unstable prodelta-slope muds at the contemporary shelf margin. The three upper Wilcox delta complexes studied in detail are, from oldest to youngest, the Duval, Zapata, and Live Oak deltas, named for the counties in which they are centered. Each complex consists of several lobes, some of which can be traced across the deep zones where the thickness increases by as much as tenfold owing to progradation over active growth faults. Characteristic coarsening-upward progradational units are interpreted from electric log patterns to include prodelta shales, delta-front sandstones, distributary channel and channel-mouth bar sandstones, and interdistributary shales and sandstones. Appreciable variability in sandstone distribution in the deltas may reflect changing importance of fluvial versus marine currents in distributing sediment along the delta front. However, all of the deltas prograded abruptly toward the shelf margin. The gulfward extent of these delta complexes is unknown, and it is concluded that appreciable quantities of sandstone remain to be explored in the deep subsurface of the trend.

  9. Damped Oscillator with Delta-Kicked Frequency

    NASA Technical Reports Server (NTRS)

    Manko, O. V.

    1996-01-01

    Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.

  10. [The return of the hepatitis delta virus].

    PubMed

    Zoutendijk, R; de Jonge, P J F; de Man, R A

    2016-01-01

    - There are several regions worldwide with a high prevalence of infection with the hepatitis delta virus (HDV) in hepatitis B virus (HBV) carriers.- Chronic HDV infection is occurring with increasing frequency due to increased immigration.- HDV transmission can take place through the same routes as HBV by simultaneous infection with both viruses (co-infection) or infection of an HBV carrier with HDV (superinfection).- Delta hepatitis is considered as the most severe form of viral hepatitis with a high risk of progression to cirrhosis and hepatocellular carcinoma.- Chronic delta hepatitis is exclusively observed in patients who are HBV carriers.- Pegylated interferon is currently the only registered therapy for patients with delta hepatitis, but leads to a persistent virological response in only a minority of them, and rarely leads to a complete cure.- New antivirals, such as viral entry blockers, prenylation inhibitors and anti-sense oligonucleotides are promising and currently being investigated in phase 2 trials. PMID:27405575

  11. Delta-nucleus dynamics: proceedings of symposium

    SciTech Connect

    Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P.

    1983-10-01

    The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta ..delta..(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe ..delta..-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented. (WHK)

  12. Delta XTE Launch Activities (Scrub #2)

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This NASA Kennedy Space Center video presents Delta XTE (X-Ray Timing Explorer) launch activities on 12/11/95. The launch was rescheduled for next weekend due to out of limit upper level wind conditions.

  13. Migration in Vulnerable Deltas: A Research Strategy

    NASA Astrophysics Data System (ADS)

    Hutton, C.; Nicholls, R. J.; Allan, A.

    2015-12-01

    C. Hutton1, & R. J. Nicholls1, , 1 University of Southampton, University Road, Southampton, Hampshire, United Kingdom, SO17 1BJ. cwh@geodata. soton.ac.ukAbstractGlobally, deltas contain 500 million people and with rising sea levels often linked to large number of forced migrants are expected in the coming century. However, migration is already a major process in deltas, such as the growth of major cities such as Dhaka and Kolkata. Climate and environmental change interacts with a range of catchment and delta level drivers, which encompass a nexus of sea-level rise, storms, freshwater and sediment supply from the catchment, land degradation, subsidence, agricultural loss and socio-economic stresses. DECCMA (Deltas, Vulnerability and Climate Change: Migration and Adaptation/CARRIA) is investigating migration in the Ganges-Brahmaputra-Meghna (GBM), Mahanadi and Volta Deltas, including the influence of climate change. The research will explore migration from a range of perspectives including governance and stakeholder analysis, demographic analysis, household surveys of sending and receiving areas, macro-economic analysis, and hazards and hotspot analysis both historically and into the future. Migration under climate change will depend on other adaptation in the deltas and this will be examined. Collectively, integrated analysis will be developed to examine migration, other adaptation and development pathways with a particular focus on the implications for the poorest. This will require the development of input scenarios, including expert-derived exogenous scenarios (e.g., climate change) and endogenous scenarios of the delta developed in a participatory manner. This applied research will facilitate decision support methods for the development of deltas under climate change, with a focus on migration and other adaptation strategies.

  14. Beteigeuze (Alpha Orionis) und Mintaka (Delta Orionis)

    NASA Astrophysics Data System (ADS)

    Vollmann, Wolfgang

    2013-02-01

    Magnitude measures transformed to Johnson V of Alpha Orionis (Betelgeuse) and Delta Orionis with a wide-angle lens and DSLR are presented and discussed. Alpha Orionis light changes are shown clearly. The primary and secondary eclipses of Delta Orionis with amplitudes of 0.12 and 0.05 mag respectively are clearly recorded. They occur near phase 0.00 and 0.50 respectively of current elements from VSX (2).

  15. Preparing Nimbus E on Delta Vehicle

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Nimbus E, the sixth spacecraft in the Nimbus series, is shown preparing for launch on December 12, 1972 from the Western Test Range (WTR), Space Launch Complex SLC-2, West, by the Thrust- Augmented Delta vehicle. The satellite was placed in an 1100-kilometer run-synchronous nearly circular polar orbit. The spacecraft was designated Nimbus 5 upon confirmation that it had achieved successful orbit. The Delta launch vehicle family started development in 1959. The Delta is composed of parts from the Thor, an intermediate-range ballistic missile, as its first stage, and the Vanguard as its second. The first Delta was launched from Cape Canaveral on May 13, 1960 and was powerful enough to deliver a 100-pound spacecraft into geostationary transfer orbit. Delta has been used to launch civil, commercial, and military satellites into orbit. For more information about Delta, please see Chapter 3 in Roger Launius and Dennis Jenkins' book To Reach the High Frontier published by The University Press of Kentucky in 2002.

  16. Lena River delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2015-01-01

    The Lena River delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging; rather, they accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases, the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8000-6000 BP (years before present), 4500-4000, 2500-1500, and 400-200 BP) and decreasing (5000, 3000, and 500 BP) Laptev Sea levels to be distinguished in the Lena Delta area.

  17. Lena River Delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2014-03-01

    The Lena River Delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of Delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging, but accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River Delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8-6 Ka, 4.5-4 Ka, 2.5-1.5 Ka, 0.4-0.2 Ka) and decreasing (5 Ka, 3 Ka, 0.5 Ka) Laptev Sea levels to be distinguished in the Lena Delta area.

  18. Delta's role in reaching the fourth environment

    NASA Technical Reports Server (NTRS)

    Grimes, D. W.; Ganoung, J. K.

    1981-01-01

    The Delta launch vehicle has played a significant role in spaceand airborne studies since its first launch in 1960, and a high volume period of service is planned for the 1980s. The historical role played by Delta in launching satellites from 1960 to the present is discussed, and vehicle modifications made during this period are summarized. It is shown that out of 154 launches, 143 proved successful for an overall reliability of 93%. The forecasted launch schedule through 1985 is also presented. Various modifications are now under way to provide spacecraft interchangeability with the Shuttle: a Payload Assist Module (PAM) is proposed to provide an orderly transition from the Delta expendable vehicle to the Shuttle reusable vehicle; the new Delta 3920 Improved Second Stage is the result of a need for improved Delta performance to meet 3910 payload capabilities; the firing sequence of the solid rocket motors was altered from five at liftoff and four during ascent to a sequence of six and three, thereby increasing spacecraft weight in geosynchronous transfer orbit. Potential future improvements discussed include the Delta 4920, 9-ft-diam fairing, booster engine performance, PAM solid motor performance, a universal second stage, a hydrogen-oxygen second stage, and large strap-on solids.

  19. River deltas: channelizing sandpiles with memory

    NASA Astrophysics Data System (ADS)

    Jerolmack, Douglas; Reitz, Meredith

    2013-03-01

    River deltas are wedges of sediment that are built via the lateral migration of self-channelizing rivers, but the timescale of this process is prohibitively long to observe in nature. Here we present laboratory results that allow us to examine how channels form and fill space to create a delta. Flow collapses into a single channel whose dimensions adjust to threshold transport conditions for the imposed sediment load. This channelization causes localized shoreline growth until the slope drops below a threshold value for sediment transport. This leads to deposition within the channel, with an upstream-migrating step akin to a stopping front in granular flows, which causes widespread flooding and the selection of a new (steeper) channel path. This cycle is remarkably periodic; delta slope oscillates between two thresholds - entrainment and distrainment - analogous to static and dynamic angles of repose. Selection of a new flow path is inherently stochastic, but previously abandoned channels act as significant attractors for the flow. Once a critical density of flow paths has been established, the flow oscillates among the same 3-5 channels indefinitely. These dynamics result in self-similar (quasi-)radial growth of delta lobes, which can be described using a simple geometric model. Despite its simplicity, the experimental system agrees well with what can be measured from natural deltas Thus, temporal and spatial patterns of deltas appear to be a robust result of mass conservation and transport thresholds.

  20. A novel mouse PKC{delta} splice variant, PKC{delta}IX, inhibits etoposide-induced apoptosis

    SciTech Connect

    Kim, Jung D.; Seo, Kwang W.; Lee, Eun A.; Quang, Nguyen N.; Cho, Hong R.; Kwon, Byungsuk

    2011-07-01

    Highlights: {yields} A novel PKC{delta} isoform, named PKC{delta}IX, that lacks the C1 domain and the ATP-binding site is ubiquitously expressed. {yields} PKC{delta}IX inhibits etoposide-induced apoptosis. {yields} PKC{delta}IX may function as an endogenous dominant negative isoform for PKC{delta}. -- Abstract: Protein kinase C (PKC) {delta} plays an important role in cellular proliferation and apoptosis. The catalytic fragment of PKC{delta} generated by caspase-dependent cleavage is essential for the initiation of etoposide-induced apoptosis. In this study, we identified a novel mouse PKC{delta} isoform named PKC{delta}IX (Genebank Accession No. (HQ840432)). PKC{delta}IX is generated by alternative splicing and is ubiquitously expressed, as seen in its full-length PKC{delta}. PKC{delta}IX lacks the C1 domain, the caspase 3 cleavage site, and the ATP binding site but preserves an almost intact c-terminal catalytic domain and a nuclear localization signal (NLS). The structural characteristics of PKC{delta}IX provided a possibility that this PKC{delta} isozyme functions as a novel dominant-negative form for PKC{delta} due to its lack of the ATP-binding domain that is required for the kinase activity of PKC{delta}. Indeed, overexpression of PKC{delta}IX significantly inhibited etoposide-induced apoptosis in NIH3T3 cells. In addition, an in vitro kinase assay showed that recombinant PKC{delta}IX protein could competitively inhibit the kinase activity of PKC{delta}. We conclude that PKC{delta}IX can function as a natural dominant-negative inhibitor of PKC{delta}in vivo.

  1. The Okavango: Whose Delta is it?

    NASA Astrophysics Data System (ADS)

    Magole, Lapologang; Magole, Lefatshe Innocent

    The Okavango Delta is amongst the largest Ramsar sites ( http://www.ramsar.org/sitelist.pdf) in the world and an important wetland for community livelihoods, conservation and tourism in Botswana. Over the years, the utilization of the delta has shifted from communal use to state control, with an increased use for conservation and tourism. This increased use for conservation and tourism has manifested in the physical expansion of the conservation area - Moremi Game Reserve and the formation of Wildlife Management Areas (WMAs) around the reserve, whose primary land use is wildlife utilization. The expansion of the conservation area has translated into several practical matters, including expansion of the area for non-hunting activities or photographic areas. The livelihoods of local communities of the Okavango delta who depended on fishing, hunter-gathering, livestock rearing, rain-fed agriculture and flood recession farming have been negatively affected by the expansion of conservation and tourism in the delta. The livelihoods alternatives in the form of Community Based Natural Resource Management (CBNRM) and tourism have not provided substitutes for the people as the communities are still reliant on the same old livelihood sources as in the past, albeit within smaller and restricted areas. This paper explores the ownership of the natural resources within the Okavango Delta. It asks and attempts to answer the following questions: Who owns and controls the use of the land? Who has access to other resources there in? Who makes the decisions on how the delta resources should be managed and used? Who benefits from the delta resources? We argue firstly that ownership of the delta as defined by legal parameters and demonstrated in natural resource management practice is vested on government. Secondly, government, after assuming ownership of the delta continues to sell its stake to the international community, at the expense of local ownership and access to resources. We

  2. A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

    SciTech Connect

    G. Ramalho, K. Tsushima

    2010-10-01

    A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.

  3. Model for the {Delta}(1600) resonance and {gamma}N{yields}{Delta}(1600) transition

    SciTech Connect

    Ramalho, G.; Tsushima, K.

    2010-10-01

    A covariant spectator constituent quark model is applied to study the {gamma}N{yields}{Delta}(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the {Delta}(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming {Delta}(1600) as the first radial excitation of {Delta}(1232), the pion cloud contributions are estimated based on an analogy with the {gamma}N{yields}{Delta}(1232) transition. To estimate the pion cloud contributions in the {gamma}N{yields}{Delta}(1600) transition, we include the relevant intermediate states, {pi}N, {pi}{Delta}, {pi}N(1440) and {pi}{Delta}(1600). Dependence on the four-momentum transfer squared, Q{sup 2}, is predicted for the magnetic dipole transition form factor, G{sub M}*(Q{sup 2}), as well as the helicity amplitudes, A{sub 1/2}(Q{sup 2}) and A{sub 3/2}(Q{sup 2}). The results at Q{sup 2}=0 are compared with the existing data.

  4. Sources and Reactivity of Terrestrial Organic Carbon to the Colville River Delta, Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Bianchi, T. S.; Rosenheim, B. E.

    2014-12-01

    Terrestrial particulate organic carbon (tPOC) delivery to nearshore deltaic regions is an important mechanism of OC storage and burial, and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. Increasing warming in the Arctic is leading to an acceleration of the hydrologic cycle, warming of permafrost, and broad shifts in vegetation. All of these changes are likely to affect the delivery, reactivity, and burial of tPOC in nearshore Arctic regions, making the Arctic an ideal place to study the effects of climate change on tPOC delivery. However, to date, most studies of tPOC delivery from North America to the Arctic Ocean have focused on large Arctic rivers like the Mackenzie and Yukon, and a significant portion of those watersheds lie in sub-Arctic latitudes, meaning that their tPOC delivery is likely not uniquely representative of the high Arctic tundra. Here, we focus on tPOC delivery by the Colville River, the largest North American river with a watershed that does not include sub-Arctic latitudes. Sediment samples from the river delta and nearby Simpson's Lagoon were taken in August of 2010 and subsequently fractionated by density, in order to study the delivery of both discrete and sediment-sorbed tPOC. Samples were analyzed for stable carbon isotopes, bulk radiocarbon, terrestrial biomarkers (including lignin-phenols, and other CuO reaction products), and aquatic biomarkers (algal pigments), and additionally a subset of the samples were analyzed by ramped pyrolysis-14C. Results show that tPOC delivery near the river mouth is sourced from coastal plain tundra, with additional delivery of tPOC from peat released into the lagoon from the seaward limit of the tundra by coastal erosion. Ramped pyrolysis-14C analysis also shows a clear differentiation between tPOC delivered by the river and tPOC delivered by coastal retreat in the lagoon. Additionally, a significant portion of the OC released by the Colville River is

  5. The DELTA MONSTER: An RPV designed to investigate the aerodynamics of a delta wing platform

    NASA Technical Reports Server (NTRS)

    Connolly, Kristen; Flynn, Mike; Gallagher, Randy; Greek, Chris; Kozlowski, Marc; Mcdonald, Brian; Mckenna, Matt; Sellar, Rich; Shearon, Andy

    1989-01-01

    The mission requirements for the performance of aerodynamic tests on a delta wind planform posed some problems, these include aerodynamic interference; structural support; data acquisition and transmission instrumentation; aircraft stability and control; and propulsion implementation. To eliminate the problems of wall interference, free stream turbulence, and the difficulty of achieving dynamic similarity between the test and actual flight aircraft that are associated with aerodynamic testing in wind tunnels, the concept of the remotely piloted vehicle which can perform a basic aerodynamic study on a delta wing was the main objective for the Green Mission - the Delta Monster. The basic aerodynamic studies were performed on a delta wing with a sweep angle greater than 45 degrees. These tests were performed at various angles of attack and Reynolds numbers. The delta wing was instrumented to determine the primary leading edge vortex formation and location, using pressure measurements and/or flow visualization. A data acquisition system was provided to collect all necessary data.

  6. Holocene evolution of a wave-dominated fan-delta: Godavari delta, India

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Nageswara Rao, K.; Nagakumar, K.; Demudu, G.; Rajawat, A.; Kubo, S.; Li, Z.

    2013-12-01

    The Godavari delta is one of the world's largest wave-dominated deltas. The Godavari River arises in the Western Ghats near the west coast of India and drains an area of about 3.1x10^5 km^2, flowing about 1465 km southeast across the Indian peninsula to the Bay of Bengal. The Godavari delta consists of a gentle seaward slope from its apex (12 m elevation) at Rajahmundry and a coastal beach-ridge plain over a distance of about 75 km and covers ~5200 km^2 as a delta plain. The river splits into two major distributary channels, the Gautami and the Vasishta, at a barrage constructed in the mid-1800s. The coastal environment of the deltaic coast is microtidal (~1 m mean tidal range) and wave-dominated (~1.5 m mean wave height in the June-September SW monsoon season, ~0.8 m in the NE monsoon season). Models of the Holocene evolution of the Godavari delta have changed from a zonal progradation model (e.g. Nageswara Rao & Sadakata, 1993) to a truncated cuspate delta model (Nageswara Rao et al., 2005, 2012). Twelve borehole cores (340 m total length), taken in the coastal delta plain during 2010-2013, yielded more than 100 C-14 dates. Sediment facies and C-14 dates from these and previous cores and remote-sensing data support a new delta evolution model. The Holocene coastal delta plain is divided into two parts by a set of linear beach ridges 12-14 km landward from the present shoreline in the central part of the delta. The location of the main depocenter (lobe) has shifted during the Holocene from 1) the center to 2) the west, 3) east, 4) center, 5) west, and 6) east. The linear beach ridges separate the first three from the last three stages. These lobe shifts are controlled by river channel shifts near the apex. Just as the current linear shoreline of the central part of the delta and the concave-up nearshore topography are the result of coastal erosion of a cuspate delta, the linear beach ridges indicate a former eroded shoreline. An unconformity within the deltaic

  7. Tracking Nile Delta vulnerability to Holocene change.

    PubMed

    Marriner, Nick; Flaux, Clément; Morhange, Christophe; Stanley, Jean-Daniel

    2013-01-01

    Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile's deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan 'depeopling', reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction. PMID:23922692

  8. {delta}-mediated pion production in nuclei

    SciTech Connect

    Praet, C.; Lalakulich, O.; Jachowicz, N.; Ryckebusch, J.

    2009-04-15

    We present a fully relativistic formalism for describing neutrino-induced {delta}-mediated single-pion production in nuclei. We assess the ambiguities stemming from the {delta} interactions and quantify the uncertainties in the axial form-factor parameters by comparing with the available bubble-chamber neutrino-scattering data. To include nuclear effects, we turn to a relativistic plane-wave impulse approximation (RPWIA) using realistic bound-state wave functions derived in the Hartree approximation to the {sigma}-{omega} Walecka model. For neutrino energies larger than 1 GeV, we show that a relativistic Fermi-gas model with appropriate binding-energy correction produces results that are comparable to the RPWIA that naturally includes Fermi motion, nuclear-binding effects, and the Pauli exclusion principle. Including {delta} medium modifications roughly halves the RPWIA cross section. Calculations for primary (prior to undergoing final-state interactions) pion production are presented for both electron- and neutrino-induced processes, and a comparison with electron-scattering data and other theoretical approaches is included. We infer that the total {delta}-production strength is underestimated by about 20 to 25%, a fraction that is due to the pionless decay modes of the {delta} in a medium. The model presented in this work can be naturally extended to include the effect of final-state interactions in a relativistic and quantum-mechanical way.

  9. Delta Coherence Protocols: The Home Update Protocol

    SciTech Connect

    Williams, C.; Reynolds, P.F.; de Supinoki, B.

    2000-07-21

    We describe a new class of directory coherence protocols called delta coherence protocols that use network guarantees to support a new and highly concurrent approach to maintain a consistent shared memory. Delta coherence protocols are more concurrent than other coherence protocols in that they allow processes to pipeline memory accesses without violating sequential consistency; support multiple concurrent readers and writers to the same cache block; and allow processes to access multiple shared variables atomically without invalidating the copies held by other processes or otherwise obtaining exclusive access to the referenced variables. Delta protocols include both update and invalidate protocols. In this paper we describe the simplest, most basic delta protocol, an update protocol called the home update protocol. Delta protocols are based on isotach network guarantees. An isotach network maintains a logical time system that allows each process to predict and control the logical time at which its messages are received. Processes use isotach guarantees to control the logical time at which their requests on shared memory appear to be executed. We prove the home update protocol is correct using logical time to reason about the order in which requests are executed.

  10. NATO-3C/Delta launch

    NASA Technical Reports Server (NTRS)

    1978-01-01

    NATO-3C, the third in a series of NATO defense-related communication satellites, is scheduled to be launched on a delta vehicle from the Eastern Test Range no earlier than November 15, 1978. NATO-3A and -3B were successfully launched by Delta vehicles in April 1976 and January 1977, respectively. The NATO-3C spacecraft will be capable of transmitting voice, data, facsimile, and telex messages among military ground stations. The launch vehicle for the NATO-3C mission will be the Delta 2914 configuration. The launch vehicle is to place the spacecraft in a synchronous transfer orbit. The spacecraft Apogee Kick motor is to be fired at fifth transfer orbit apogee to circularize its orbit at geosynchronous altitude of 35,900 km(22,260 miles) above the equator over the Atlantic Ocean somewhere between 45 and 50 degrees W longitude.

  11. Delta receptors in the rat vas deferens.

    PubMed

    Smith, C F; Carter, A

    1986-12-01

    The effects of the delta-selective antagonist ICI 174864 and naltrexone on the dose-response curves to the mu-selective agonist RX 783006 and D-ala-D-leucine enkephalin (DADL) have been investigated in the rat isolated vas deferens preparation (RVD) set up in Krebs solution containing half the normal Ca++ concentration. The results obtained provide very strong evidence for the existence of both mu- and delta-receptors in this preparation. The Ke values of a number of opioid antagonists v. DADL in the RVD have been determined and compared to the Ke values obtained in the mouse vas deferens assay (MVD). The very good correlation (slope = 1.01, r = 0.98) obtained between the Ke values from the 2 preparations confirms the presence of a delta-receptor in the RVD. PMID:3030209

  12. Delta capability for launch of communications satellites

    NASA Technical Reports Server (NTRS)

    Grimes, D. W.; Russell, W. A., Jr.; Kraft, J. D.

    1982-01-01

    The evolution of capabilities and the current performance levels of the Delta launch vehicle are outlined. The first payload was the Echo I passive communications satellite, weighing 179 lb, and placed in GEO in 1960. Emphasis since then has been to use off-the-shelf hardware where feasible. The latest version in the 3924 first stage, 3920 second stage, and Pam D apogee kick motor third stage. The Delta is presently equipped to place 2800 lb in GEO, as was proven with the 2717 lb Anik-D1 satellite. The GEO payload placement performance matches the Shuttle's, and work is therefore under way to enhance the Delta performance to handle more massive payloads. Installation of the Castor-IV solid motor separation system, thereby saving mass by utilizing compressed nitrogen, rather than mechanical thrusters to remove the strap-on boosters, is indicated, together with use of a higher performance propellant and a wider nose fairing.

  13. Mutagenesis of the borage Delta(6) fatty acid desaturase.

    PubMed

    Sayanova, O; Beaudoin, F; Libisch, B; Shewry, P; Napier, J

    2000-12-01

    The consensus sequence of the third histidine box of a range of Delta(5), Delta(6), Delta(8) and sphingolipid desaturases differs from that of the membrane-bound non-fusion Delta(12) and Delta(15) desaturases in the presence of glutamine instead of histidine. We have used site-directed mutagenesis to determine the importance of glutamine and other residues of the third histidine box and created a chimaeric enzyme to determine the ability of the Cyt b(5) fusion domain from the plant sphingolipid desaturase to substitute for the endogenous domain of the Delta(6) desaturase. PMID:11171152

  14. The Delta Launch Vehicle Model 2914 Series

    NASA Technical Reports Server (NTRS)

    Gunn, C. R.

    1973-01-01

    The newest Delta launch vehicle configuration, Model 2914 is described for potential users together with recent flight results. A functional description of the vehicle, its performance, flight profile, flight environment, injection accuracy, spacecraft integration requirements, user organizational interfaces, launch operations, costs and reimbursable users payment plan are provided. The versatile, relatively low cost Delta has a flight demonstrated reliability record of 92 percent that has been established in 96 launches over twelve years while concurrently undergoing ten major upratings to keep pace with the ever increasing performance and reliability requirements of its users. At least 40 more launches are scheduled over the next three years from the Eastern and Western Test Ranges.

  15. All optical binary delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  16. How Deltas Die - a Case Study of the End of Sedimentation in Two Giant Deltas

    NASA Astrophysics Data System (ADS)

    Macdonald, D.; Robinson, P.; Nicholson, U.

    2013-12-01

    Most well-studied deltas are on passive margins (e.g. Mississippi, Rhone, Ebro), where the main tectonic control on accommodation space is thermal subsidence. As long as the main river in the sediment routing system keeps flowing, there is no particular reason for sedimentation to end, and some deltas have a history extending more than 100 Ma (e.g. Niger at 130 Ma). However, some very large deltas can build out over active margins. For example, the Amur, Orinoco, and Colorado (US) deltas all straddle strike-slip plate boundaries and are much less long-lived than their passive margin counterparts. This paper looks in detail at the end of the deltaic sedimentation in the Pliocene deltas of the Amur River on the island of Sakhalin, and the Colorado River in the Fish Creek-Vallecito Basin of southern California. In both cases the deltas are sand-rich with distant provenances in East Asia and the Colorado Plateau respectively; also they both coexist with locally derived clastic sedimentation. Despite these similarities, there are significant differences between the two deltas as a direct result of the differences in plate boundary movement rates and tectonic state. On Sakhalin, the plate boundary has moved at about 1.95 mm a-1 during the Pliocene and has been in a transpressional state. Primary deltaic sedimentation ended by a three main mechanisms: uplift of the island along the transpressional plate boundary detached the delta from the trunk stream; growth of anticlines over strands of the plate boundary disrupted the consequent delta-top drainage; and late sedimentation involved reworking of the far-travelled deltaic material. In California, where the plate boundary has moved at about 50 mm a-1 in the Pliocene, deltaic sedimentation ceased by translation of the receiving basin from the river mouth. New field and mineralogical data suggest that Colorado River sedimentation waned over a period of about 1 Ma in the Late Pliocene, and was gradually overwhelmed by locally

  17. Modeling delta growth and channel geometry on Wax Lake Delta, Louisiana. Preliminary results

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Czapiga, M. J.; Li, C.; Shaw, J. B.; Parker, G.

    2013-12-01

    A numerical model of delta growth, in which the distributary channels are assumed to have self-constructed their cross sections, is validated on Wax Lake Delta, Louisiana. As in previous laterally averaged models of delta growth, the delta is divided in a low slope delta top, a steep delta front and a low slope basement. The flow on the delta top is assumed steady, and a backwater formulation is implemented. Since one or more channels can actively transport water and sediment on the delta top during floods, we simplify the problem by assuming that the bed material is transported in one rectangular channel, with width and depth roughly equal to the sum of the active channel widths, and to the average depth of the active channels. The problem is characterized by one equation (i.e. the backwater equation) in two unknowns, the channel width and depth. Another equation is thus needed to close the problem. Under the assumptions that 1) the system is at bankfull flow, and 2) the Shields number in the channels is equal to its channel formative value, our closure relation is a channel-formative criterion. In particular, a recently derived relation to estimate the formative (bankfull) Shields number as a function of the friction slope is implemented. Recent field work on Wax Lake Delta shows that the distributary channels are incising into a relatively stiff basement. In our model we do not attempt to directly model channel incision, but we implicitly account for it with a modified formulation to compute the shoreline migration rate. In this formulation the bed material at the shoreline is trapped in the non-channelized portion of the delta front only. Measured and numerical shoreline migration rates, longitudinal profiles of delta elevation, and channel geometry, i.e. width and depth, are compared. In the relatively near future we plan to 1) use our model to estimate land-building potential of engineered diversions of the Mississippi River, and 2) couple the present model

  18. Susceptibility of Naegleria fowleri to delta 9-tetrahydrocannabinol.

    PubMed Central

    Pringle, H L; Bradley, S G; Harris, L S

    1979-01-01

    Growth of the pathogenic amoeboflagellate Naegleria fowleri is inhibited by delta 9-tetrahydrocannabinol (delta 9-THC). delta 9-THC is amoebostatic at 5 to 50 micrograms/ml. delta 9-THC prevents enflagellation and encystment, but does not impair amoeboid movement. Calf serum at 10 and 20% (vol/vol) reduces the antiamoeba activity of delta 9-THC. Only 1-methoxy delta 8-tetrahydrocannabinol, of 17 cannabinoids tested, failed to inhibit growth of N. fowleri. Antinaeglerial activity was not markedly altered by opening the pyran ring, by converting the cyclohexyl ring to an aromatic ring, or by reversing the hydroxyl and pentyl groups on the benzene ring. delta 9-THC prevented the cytopathic effect of N. fowleri on African green monkey (Vero) cells and human epithelioma (HEp-2) cells in culture. delta 9-THC afforded modest protection to mice infected with N. fowleri. Images PMID:526010

  19. Depositional history of the Lagniappe Delta, northern Gulf of Mexico

    USGS Publications Warehouse

    Kindinger, J.L.

    1989-01-01

    The northern Gulf of Mexico continental shelf is characterized by superimposing deltas. One such delta, informally named Lagniappe, extends east of the Mississippi Delta from mid-shelf to the continental slope. This late Wisconsinan delta is adjacent to, but not associated with the Mississippi Delta complex: the fluvial source was probably the ancient Pearl and/or Mobile Rivers. The fluvially dominated Lagniappe Delta is characterized by complex sigmoid-oblique seismic-reflection patterns, indicating delta switching of high-energy sand-prone facies to low-energy facies. The areal distribution and sediment thickness of the delta were partially controlled by two diapirs. ?? 1989 Springer-Verlag New York Inc.

  20. Applications of Dirac's Delta Function in Statistics

    ERIC Educational Resources Information Center

    Khuri, Andre

    2004-01-01

    The Dirac delta function has been used successfully in mathematical physics for many years. The purpose of this article is to bring attention to several useful applications of this function in mathematical statistics. Some of these applications include a unified representation of the distribution of a function (or functions) of one or several…

  1. Ribonucleoprotein complexes of hepatitis delta virus.

    PubMed Central

    Ryu, W S; Netter, H J; Bayer, M; Taylor, J

    1993-01-01

    Human hepatitis delta virus (HDV) is a subviral satellite agent of hepatitis B virus (HBV). The envelope proteins of HDV are provided by the helper virus, HBV, but very little is known about the internal structure of HDV. The particles contain multiple copies of the delta antigen and an unusual RNA genome that is small, about 1,700 nucleotides in length, single stranded, and circular. By using UV cross-linking, equilibrium density centrifugation, and immunoprecipitation, we obtained evidence consistent with the interpretation that delta antigen and genomic RNA form a stable ribonucleoprotein (RNP) complex within the virion. Furthermore, electron-microscopic examination of the purified viral RNP revealed a roughly spherical core-like structure with a diameter of 18.7 +/- 2.5 nm. We also isolated HDV-specific RNP structures from the nuclei of cells undergoing HDV genome replication; both the genome and antigenome (a complement of the genome) of HDV were found to be in such complexes. From the equilibrium density analyses of the viral and nuclear RNPs, we were able to deduce the number of molecules of delta antigen per molecule of HDV RNA. For virions, this number was predominantly ca. 70, which was larger than for the nuclear RNPs, which were more heterogeneous, with an average value of ca. 30. Images PMID:8497052

  2. Assembly of hepatitis delta virus particles.

    PubMed Central

    Ryu, W S; Bayer, M; Taylor, J

    1992-01-01

    Hepatitis delta virus (HDV) is a subviral satellite of hepatitis B virus (HBV). Since the RNA genome of HDV can replicate in cultured cells in the absence of HBV, it has been suggested that the only helper function of HBV is to supply HBV coat proteins in the assembly process of HDV particles. To examine the factors involved in such virion assembly, we transiently cotransfected cells with various hepadnavirus constructs and cDNAs of HDV and analyzed the particles released into the medium. We report that the HDV genomic RNA and the delta antigen can be packaged by coat proteins of either HBV or the related hepadnavirus woodchuck hepatitis virus (WHV). Among the three co-carboxy-terminal coat proteins of WHV, the smallest form was sufficient to package the HDV genome; even in the absence of HDV RNA, the delta antigen could be packaged by this WHV coat protein. Also, of the two co-amino-terminal forms of the delta antigen, only the larger form was essential for packaging. Images PMID:1548764

  3. Spectroscopic Survey Of Delta Scuti Stars

    NASA Astrophysics Data System (ADS)

    Kahraman Alicavus, Filiz; Niemczura, Ewa; Polinska, Magdalena; Helminiak, Krzysztof G.; Lampens, Patricia; Molenda-Zakowicz, Joanna; Ukita, Nobuharu; Kambe, Eiji

    2016-07-01

    We present the results of a spectroscopic study of pulsating stars of Delta Scuti type. The spectral types and luminosity classes, fundamental atmospheric parameters (the effective temperature, surface gravity, microturbulent velocity), detailed chemical composition and projected rotational velocities of a significant number of Delta Scuti-type stars were derived. The spectral classification was performed by comparing the spectra of our targets with the spectra of standard stars. The atmospheric parameters were determined by using different methods. The initial atmospheric parameters were derived from the analysis of photometric indices, the spectral energy distribution and the hydrogen lines, while the final atmospheric parameters were obtained from the analysis of iron lines. The spectrum synthesis method was used to determine chemical compositions of the investigated stars. As a result, we derived accurate atmospheric parameters, the projected rotational velocities and the abundance patterns of analysed sample. These results allow us to examine the position of Delta Scuti-type stars in the H-R diagram, and to investigate the effect of the rotational velocity on pulsation properties and a chemical difference between the Delta Scuti-type stars and the Gamma Doradus and A-F type hybrid stars.

  4. Backwater controls of avulsion location on deltas

    NASA Astrophysics Data System (ADS)

    Chatanantavet, Phairot; Lamb, Michael P.; Nittrouer, Jeffrey A.

    2012-01-01

    River delta complexes are built in part through repeated river-channel avulsions, which often occur about a persistent spatial node creating delta lobes that form a fan-like morphology. Predicting the location of avulsions is poorly understood, but it is essential for wetland restoration, hazard mitigation, reservoir characterization, and delta morphodynamics. Following previous work, we show that the upstream distance from the river mouth where avulsions occur is coincident with the backwater length, i.e., the upstream extent of river flow that is affected by hydrodynamic processes in the receiving basin. To explain this observation we formulate a fluvial morphodynamic model that is coupled to an offshore spreading river plume and subject it to a range of river discharges. Results show that avulsion is less likely in the downstream portion of the backwater zone because, during high-flow events, the water surface is drawn down near the river mouth to match that of the offshore plume, resulting in river-bed scour and a reduced likelihood of overbank flow. Furthermore, during low-discharge events, flow deceleration near the upstream extent of backwater causes enhanced deposition locally and a reduced channel-fill timescale there. Both mechanisms favor preferential avulsion in the upstream part of the backwater zone. These dynamics are fundamentally due to variable river discharges and a coupled offshore river plume, with implications for predicting delta response to climate and sea level change, and fluvio-deltaic stratigraphy.

  5. The Delta Team: Empowering Adolescent Girls.

    ERIC Educational Resources Information Center

    Hood, Marian White

    1994-01-01

    In response to adolescent girls' concerns about teen violence, rumors, grooming, careers, and equity, four women teachers and a woman administrator at a Maryland middle school developed the Delta Program. The program provides positive learning experiences, teaches social skills and conflict management techniques, empowers girls through mentoring…

  6. Delta Scorpii unusual brightening to first magnitude

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino

    2016-01-01

    The Be star delta Scorpii with a range of variability between 2.35 and 1.65 in visible light is having an unusual brightening to magnitude mV=0.8, as measured on 31 Jan 2016 at 3:56 UT and 5:36 UT from Lanciano, Italy.

  7. Definition of the {delta} mass and width

    SciTech Connect

    Djukanovic, D.; Scherer, S.; Gegelia, J.

    2007-08-01

    In the framework of effective field theory we show that, at two-loop order, the mass and width of the {delta} resonance defined via the (relativistic) Breit-Wigner parametrization both depend on the choice of field variables. In contrast, the complex-valued position of the pole of the propagator is independent of this choice.

  8. Scott on Slope of Hadley Delta

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Astronaut David R. Scott, mission commander, with tongs and gnomon in hand, studies a boulder on the slope of Hadley Delta during the Apollo 15 lunar surface extravehicular activity. The Lunar Roving Vehicle (LRV) or Rover is in right foreground. View is looking slightly south of west. 'Bennett Hill' is at extreme right. Astronaut James B. Irwin, lunar module pilot, took this photograph.

  9. Phi Delta Kappa at the Threshold

    ERIC Educational Resources Information Center

    Walling, Donovan R.

    2006-01-01

    Since its fraternal origins a century ago, Phi Delta Kappa (PDK) International has been foremost a society of individuals joined together in professional collegiality and dedicated to tenets of leadership, service, and research in education. As PDK crosses the threshold into its second century, that early spirit of association lit in 1906, like…

  10. Faculty Salaries at Delta College. Research Report.

    ERIC Educational Resources Information Center

    Evans, John W.

    In 1989, a study was conducted of faculty salaries at California's San Joaquin Delta Community College (SJDCC). Salary results were compared with community college districts in the State of California, with two specially selected subgroups of colleges comparable to SJDCC, and with all of California's major public and private four-year…

  11. San Joaquin Delta College Student Athlete Study.

    ERIC Educational Resources Information Center

    Lewis, Merrilee R.; Marcopulos, Ernest

    In spring 1988, a study was conducted of students who participated in college athletics at San Joaquin Delta College (SJDC) between 1983-84 and 1987-88. Data collected on each student athlete included ethnicity, sport, place of residence, initial and current reading level, total grade point average (GPA), GPA in athletics and physical education…

  12. 21 CFR 184.1318 - Glucono delta-lactone.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Glucono delta-lactone. 184.1318 Section 184.1318... Listing of Specific Substances Affirmed as GRAS § 184.1318 Glucono delta-lactone. (a) Glucono delta-lactone (C6H10O6, CAS Reg. No. 90-80-2), also called D-gluconic acid delta-lactone or...

  13. 21 CFR 184.1318 - Glucono delta-lactone.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glucono delta-lactone. 184.1318 Section 184.1318... GRAS § 184.1318 Glucono delta-lactone. (a) Glucono delta-lactone (C6H10O6, CAS Reg. No. 90-80-2), also called D-gluconic acid delta-lactone or D-glucono-1,5-lactone, is the cyclic 1,5-intramolecular ester...

  14. Hard breakup of the deuteron into two {Delta} isobars

    SciTech Connect

    Granados, Carlos G.; Sargsian, Misak M.

    2011-05-15

    We study high-energy photodisintegration of the deuteron into two {Delta} isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn{yields}{Delta}{Delta} scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn{yields}{Delta}{Delta} scattering. We predict that the cross section of the deuteron breakup to {Delta}{sup ++}{Delta}{sup -} is 4-5 times larger than that of the breakup to the {Delta}{sup +}{Delta}{sup 0} channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard {Delta} isobars are the result of the disintegration of the preexisting {Delta}{Delta} components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both {Delta}{sup ++}{Delta}{sup -} and {Delta}{sup +}{Delta}{sup 0} channels to be similar.

  15. 21 CFR 184.1318 - Glucono delta-lactone.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Glucono delta-lactone. 184.1318 Section 184.1318... Listing of Specific Substances Affirmed as GRAS § 184.1318 Glucono delta-lactone. (a) Glucono delta-lactone (C6H10O6, CAS Reg. No. 90-80-2), also called D-gluconic acid delta-lactone or...

  16. {Delta}G and {Delta}q-bar measurements at PHENIX

    SciTech Connect

    Okada, Kensuke; Collaboration: PHENIX Collaboration

    2011-12-14

    RHIC provides a unique opportunity to address the components of the proton spin. In comparison to deep inelastic scattering experiments, the gluon is the main player in proton-proton collisions. PHENIX has measured double spin asymmetries of various processes. Those contain the information of the gluon spin component ({Delta}G). In addition high energy collisions open the unique channel to access flavor dependent information of quark polarization through the real W boson production. Because of the feature of weak interaction, the parity violating process defines the helicity of quarks in the interaction. The single spin asymmetry is the observable. It is especially interesting to probe anti-quark components ({Delta}q-bar). In this article, we report the recent progress of {Delta}G and {Delta}q-bar measurements at PHENIX.

  17. SDO Delta H Mode Design and Analysis

    NASA Technical Reports Server (NTRS)

    Mason, Paul A.; Starin, Scott R.

    2007-01-01

    While on orbit, disturbance torques on a three axis stabilized spacecraft tend to increase the system momentum, which is stored in the reaction wheels. Upon reaching the predefined momentum capacity (or maximum wheel speed) of the reaction wheel, an external torque must be used to unload the momentum. The purpose of the Delta H mode is to manage the system momentum. This is accomplished by driving the reaction wheels to a target momentum state while the attitude thrusters, which provide an external torque, are used to maintain the attitude. The Delta H mode is designed to meet the mission requirements and implement the momentum management plan. Changes in the requirements or the momentum management plan can lead to design changes in the mode. The momentum management plan defines the expected momentum buildup trend, the desired momentum state and how often the system is driven to the desired momentum state (unloaded). The desired momentum state is chosen based on wheel capacity, wheel configuration, thruster layout and thruster sizing. For the Solar Dynamics Observatory mission, the predefined wheel momentum capacity is a function of the jitter requirements, power, and maximum momentum capacity. Changes in jitter requirements or power limits can lead to changes in the desired momentum state. These changes propagate into the changes in the momentum management plan and therefore the Delta H mode design. This paper presents the analysis and design performed for the Solar Dynamics Observatory Delta H mode. In particular, the mode logic and processing needed to meet requirements is described along with the momentum distribution formulation. The Delta H mode design is validated using the Solar Dynamics Observatory High Fidelity simulator. Finally, a summary of the design is provided along with concluding remarks.

  18. Tracking Nile Delta Vulnerability to Holocene Change

    PubMed Central

    Marriner, Nick; Flaux, Clément; Morhange, Christophe; Stanley, Jean-Daniel

    2013-01-01

    Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the ‘monsoon pacemaker’, attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile’s deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan ‘depeopling’, reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world’s deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction. PMID:23922692

  19. 78 FR 45592 - DeltaPoint Capital IV, LP;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... ADMINISTRATION DeltaPoint Capital IV, LP; Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that DeltaPoint Capital IV, L.P., 45 East Avenue... Business Administration (``SBA'') Rules and Regulations (13 CFR 107.730). DeltaPoint Capital IV,...

  20. De-Mystifying the Dirac [delta]-Function

    ERIC Educational Resources Information Center

    Lutzer, Carl V.

    2007-01-01

    In this article, we discuss an alternative method of teaching students about the Dirac [delta]-function. The method provides students with the mechanical tools they need in order to work with the [delta]-function in practice, while also fostering a sense of cohesion in the calculus curriculum by presenting the [delta]-function as an evolution of…

  1. Genetics Home Reference: activated PI3K-delta syndrome

    MedlinePlus

    ... Health Conditions activated PI3K-delta syndrome activated PI3K-delta syndrome Enable Javascript to view the expand/collapse ... PDF Open All Close All Description Activated PI3K-delta syndrome is a disorder that impairs the immune ...

  2. The Niger Delta petroleum system; Niger Delta Province, Nigeria, Cameroon, and equatorial Guinea, Africa

    USGS Publications Warehouse

    Tuttle, Michele L.W.; Charpentier, Ronald R.; Brownfield, Michael E.

    1999-01-01

    In the Niger Delta province, we have identified one petroleum system--the Tertiary Niger Delta (Akata-Agbada) petroleum system. The delta formed at the site of a rift triple junction related to the opening of the southern Atlantic starting in the Late Jurassic and continuing into the Cretaceous. The delta proper began developing in the Eocene, accumulating sediments that now are over 10 kilometers thick. The primary source rock is the upper Akata Formation, the marine-shale facies of the delta, with possibly contribution from interbedded marine shale of the lowermost Agbada Formation. Oil is produced from sandstone facies within the Agbada Formation, however, turbidite sand in the upper Akata Formation is a potential target in deep water offshore and possibly beneath currently producing intervals onshore. Known oil and gas resources of the Niger Delta rank the province as the twelfth largest in the world. To date, 34.5 billion barrels of recoverable oil and 93.8 trillion cubic feet of recoverable gas have been discovered. In 1997, Nigeria was the fifth largest crude oil supplier to the United States, supplying 689,000 barrels/day of crude.

  3. Geophysical Investigations of Ground Ice in the Arctic: Considerations for Mars

    NASA Astrophysics Data System (ADS)

    Williams, K. K.; de Pascale, G. P.; Grant, J. A.; Pollard, W. H.

    2007-12-01

    Our understanding of Mars has been advanced with the continuing successes of MARSIS and SHARAD. As we move forward with studying ice deposits on Mars, it is important to consider how to efficiently collect data with available (or future) instrument resources. Although a suite of instruments are currently operating at Mars, little is known about the shallow subsurface, up to depths of several meters, except where outcrops can be extrapolated into the subsurface. When considering deposits of ground ice that are most accessible, it will be those encountered within a few meters of the surface that require the least amount of energy and effort to sample or mine, whether by robots or humans. The only planned mission that will investigate the top meters of Mars is the ESA ExoMars rover which includes the WISDOM ground penetrating radar (GPR). In order to understand how to quickly and efficiently detect potential resources of ground ice, field studies in the Mackenzie Delta, NWT, Canada, were undertaken using a combination of ground penetrating radar and capacitive-coupled resistivity (CCR) measurements. We will present survey data collected along coincident transects with commercial GPR and CCR systems at a variety of locations and ground ice settings throughout the Mackenzie Delta. In addition, we will show data collected with the Strata Mars GPR prototype antenna which produced data comparable to (and sometimes indistinguishable from) the commercial GPR antennas. Part of the motivation for using these two geophysical techniques was to demonstrate the capabilities of combined measurements to provide information about ice content and distribution beyond what could be accomplished using either technique alone. In addition to showing that combined GPR and CCR geophysical surveys have the ability to map massive ground ice, ice-rich sediments, ice wedges, thermokarst, and basic stratigraphic relationships, field measurements also reaffirmed that these geophysical measurements

  4. 78 FR 21491 - DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ... ADMINISTRATION DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption... that DeltaPoint Capital IV, L.P. and DeltaPoint Capital IV (New York), L.P., 45 East Avenue, 6th Floor... Business Administration (``SBA'') Rules and Regulations (13 CFR 107.730). DeltaPoint Capital IV,...

  5. On the 'delta-equations' for vortex sheet evolution

    NASA Technical Reports Server (NTRS)

    Rottman, James W.; Stansby, Peter K.

    1993-01-01

    We use a set of equations, sometimes referred to as the 'delta-equations', to approximate the two-dimensional inviscid motion of an initially circular vortex sheet released from rest in a cross-flow. We present numerical solutions of these equations for the case with delta-square = 0 (for which the equations are exact) and for delta-square greater than 0. For small values of the smoothing parameter delta, a spectral filter must be used to eliminate spurious instabilities due to round-off error. Two singularities appear simultaneously in the vortex sheet when delta-square = 0 at a critical time t(c). After t(c), the solutions do not converge as the computational mesh is refined. With delta-square greater than 0, converged solutions were found for all values of delta-square when t is less than t(c), and for all but the two smallest values of delta-square used when t is greater than t(c). Our results show that, when delta-square is greater than 0, the vortex sheet deforms into two doubly branched spirals some time after t(c). The limiting solution as delta approaching 0 clearly exists and equals the delta = 0 solution when t is less than t(c).

  6. Clostridium perfringens Delta-Toxin Induces Rapid Cell Necrosis

    PubMed Central

    Seike, Soshi; Miyamoto, Kazuaki; Kobayashi, Keiko; Takehara, Masaya; Nagahama, Masahiro

    2016-01-01

    Clostridium perfringens delta-toxin is a β-pore-forming toxin and a putative pathogenic agent of C. perfringens types B and C. However, the mechanism of cytotoxicity of delta-toxin remains unclear. Here, we investigated the mechanisms of cell death induced by delta-toxin in five cell lines (A549, A431, MDCK, Vero, and Caco-2). All cell lines were susceptible to delta-toxin. The toxin caused rapid ATP depletion and swelling of the cells. Delta-toxin bound and formed oligomers predominantly in plasma membrane lipid rafts. Destruction of the lipid rafts with methyl β-cyclodextrin inhibited delta-toxin-induced cytotoxicity and ATP depletion. Delta-toxin caused the release of carboxyfluorescein from sphingomyelin-cholesterol liposomes and formed oligomers; toxin binding to the liposomes declined with decreasing cholesterol content in the liposomes. Flow cytometric assays with annexin V and propidium iodide revealed that delta-toxin treatment induced an elevation in the population of annexin V-negative and propidium iodide-positive cells. Delta-toxin did not cause the fragmentation of DNA or caspase-3 activation. Furthermore, delta-toxin caused damage to mitochondrial membrane permeability and cytochrome c release. In the present study, we demonstrate that delta-toxin produces cytotoxic activity through necrosis. PMID:26807591

  7. Isomerization of delta-9-THC to delta-8-THC when tested as trifluoroacetyl-, pentafluoropropionyl-, or heptafluorobutyryl- derivatives.

    PubMed

    Holler, Justin M; Smith, Michael L; Paul, Shom N; Past, Marilyn R; Paul, Buddha D

    2008-05-01

    For GC-MS analysis of delta-9-tetrahydrocannabinol (delta-9-THC), perfluoroacid anhydrides in combination with perfluoroalcohols are commonly used for derivatization. This reagent mixture is preferred because it allows simultaneous derivatization of delta-9-THC and its acid metabolite, 11-nor-delta-9-THC-9-carboxylic acid present in biological samples. When delta-9-THC was derivatized by trifluoroacetic anhydride/hexafluoroisopropanol (TFAA/HFIPOH) and analyzed by GC-MS using full scan mode (50-550 amu), two peaks (P1 and P2) with an identical molecular mass of 410 amu were observed. On the basis of the total ion chromatogram (TIC), P1 with a shorter retention time (RT) was the major peak (TIC 84%). To identify the peaks, delta-8-THC was also tested under the same conditions. The RT and spectra of the major peak (TIC 95%) were identical with that of P1 for delta-9-THC. A minor peak (5%) present also correlated well with the latter peak (P2) for the delta-9-THC derivative. The fragmentation pathway of P1 was primarily demethylation followed by retro Diels-Alder fragmentation (M - 15-68, base peak 100%) indicating P1 as a delta-8-THC-trifluoroacetyl compound. This indicated that delta-9-THC isomerized to delta-8-THC during derivatization with TFAA/HFIPOH. Similar results were also observed when delta-9-THC was derivatized with pentafluoropropionic anhydride/pentafluoropropanol or heptafluorobutyric anhydride/heptafluorobutanol. No isomerization was observed when chloroform was used in derivatization with TFAA. In this reaction, the peaks of delta-8-THC-TFA and delta-9-THC-TFA had retention times and mass spectra matching with P1 and P2, respectively. Because of isomerization, perfluoroacid anhydrides/perfluoroalcohols are not suitable derivatizing agents for analysis of delta-9-THC; whereas the TFAA in chloroform is suitable for the analysis. PMID:18205240

  8. On regularizations of the Dirac delta distribution

    NASA Astrophysics Data System (ADS)

    Hosseini, Bamdad; Nigam, Nilima; Stockie, John M.

    2016-01-01

    In this article we consider regularizations of the Dirac delta distribution with applications to prototypical elliptic and hyperbolic partial differential equations (PDEs). We study the convergence of a sequence of distributions SH to a singular term S as a parameter H (associated with the support size of SH) shrinks to zero. We characterize this convergence in both the weak-* topology of distributions and a weighted Sobolev norm. These notions motivate a framework for constructing regularizations of the delta distribution that includes a large class of existing methods in the literature. This framework allows different regularizations to be compared. The convergence of solutions of PDEs with these regularized source terms is then studied in various topologies such as pointwise convergence on a deleted neighborhood and weighted Sobolev norms. We also examine the lack of symmetry in tensor product regularizations and effects of dissipative error in hyperbolic problems.

  9. Space Radar Image of Mississippi Delta

    NASA Technical Reports Server (NTRS)

    1999-01-01

    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. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars

  10. Effect of carbonitride dissolution on T{sub {delta}} and V{sub {delta}} of austenitic steels

    SciTech Connect

    Yang Ruzeng; Dai Qixun

    1997-03-01

    The authors deal with the effect of carbide dissolution on the {gamma}/{gamma}+{delta} boundary temperature, T{sub {delta}}, and the {delta} phase volume, V{sub {delta}}, as well as the equilibrium relation between the alloying elements at the {gamma}/{gamma}+{delta} boundary of austenitic steels at high temperature, and study the variation of the ferrite volume with temperature in {alpha}+{gamma} dual phase steel. The relevant expressions are derived from many experimental results, which may provide a basis for quantitative calculation, the design of compositions, the determination of working processes and prediction of the mechanical properties and microstructure of the austenitic steels.

  11. An asteroseismological analysis of Delta Scuti

    NASA Astrophysics Data System (ADS)

    Templeton, M. R.; McNamara, B. J.

    1996-10-01

    One of us (BJM) observed Delta Scuti during the period of June 1983 to September 1988; observations in 1983-85 were conducted at the Tortugas Moutain observatory, New Mexico; in 1987 were conducted in a multisite campaign from New Mexico (by S. Barch), CTIO (by BJM), and SAAO (by K. Sekiguchi); and in 1988 were conducted at CTIO. We have 6515 Stromgren y differential magnitudes spanning a total of 1928.6 days with a sigma per point of approx. 7 mmag.

  12. Adaptive Delta Management: cultural aspects of dealing with uncertainty

    NASA Astrophysics Data System (ADS)

    Timmermans, Jos; Haasnoot, Marjolijn; Hermans, Leon; Kwakkel, Jan

    2016-04-01

    Deltas are generally recognized as vulnerable to climate change and therefore a salient topic in adaptation science. Deltas are also highly dynamic systems viewed from physical (erosion, sedimentation, subsidence), social (demographic), economic (trade), infrastructures (transport, energy, metropolization) and cultural (multi-ethnic) perspectives. This multi-faceted dynamic character of delta areas warrants the emergence of a branch of applied adaptation science, Adaptive Delta Management, which explicitly focuses on climate adaptation of such highly dynamic and deeply uncertain systems. The application of Adaptive Delta Management in the Dutch Delta Program and its active international dissemination by Dutch professionals results in the rapid dissemination of Adaptive Delta Management to deltas worldwide. This global dissemination raises concerns among professionals in delta management on its applicability in deltas with cultural conditions and historical developments quite different from those found in the Netherlands and the United Kingdom where the practices now labelled as Adaptive Delta Management first emerged. This research develops an approach and gives a first analysis of the interaction between the characteristics of different approaches in Adaptive Delta Management and their alignment with the cultural conditions encountered in various delta's globally. In this analysis, first different management theories underlying approaches to Adaptive Delta Management as encountered in both scientific and professional publications are identified and characterized on three dimensions: The characteristics dimensions used are: orientation on today, orientation on the future, and decision making (Timmermans, 2015). The different underlying management theories encountered are policy analysis, strategic management, transition management, and adaptive management. These four management theories underlying different approaches in Adaptive Delta Management are connected to

  13. Calibration issues in delta alpha /alpha .

    NASA Astrophysics Data System (ADS)

    Molaro, Paolo; Centurión, Miriam; Levshakov, Sergei

    Laser Comb Wavelength calibration shows that the ThAr one is locally unreliable with possible deviations of up to 100 {m s}-1 within one order range, while delivering an overall 1 {m s}-1 accuracy (Wilken et al 2009). Such deviation corresponds to delta alpha /alpha ≈ 7* 10-6 for a Fe II-Mg II pair. Comparison of line shifts among the 5 Fe II lines, with almost identical sensitivity to fine structure constant changes, offers a clean way to directly test the presence of possible local wavelength calibration errors of whatever origin. We analyzed 5 absorption systems, with zabs ranging from 1.15 to 2.19 towards 3 bright QSOs. The results show that while some lines are aligned within 20 {m s}-1, others reveal large deviations reaching 200 {m s}-1 or higher and corresponding to a delta alpha /alpha > 10-5 level. The origin of these deviations is not clearly identified but could be related to the adaptation of wavelength calibration to CCD manufacturing irregularities. These results suggest that to draw conclusions from delta alpha /alpha analysis based on one or only few lines must be done with extreme care.

  14. WESTAR-V launch on delta

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The WESTAR-V, the second in a series of second-generation, large, 24-transponder communications satellites developed for the Space Communications Company is discussed. It is scheduled to be launched on a Delta vehicle from the Eastern Space and Missile Center no earlier than June 8, 1982. The launch support for this mission will be provided by NASA, on a reimbursable basis, to the Space Communications Company for a fixed price of $25.OM. The launch vehicle for the WESTAR-V mission will be the Delta 3910 configuration which incorporates an extended long tank Thor booster, nine Castor IV strap-on motors, a TR-201 second stage, and an 8-foot fairing. The Delta launch vehicle will place the spacecraft along a suborbital trajectory. The PAM-D stage will then thrust it to a synchronous transfer orbit. Three days after launch, the spacecraft apogee kick motor will be fired to circularize its orbit at geosynchronous altitude of 19,300 NM above the equator at approxmately 75 degrees west longitude.

  15. Upper Devonian Catskill delta of West Virginia

    SciTech Connect

    Donaldson, A.C.; Lewis, J.S.; Mumcuoglu, C.; Boswell, R.; Peace, K.; Jewell, G.

    1984-12-01

    Oil and gas reservoir rocks of the Upper Devonian of West Virginia were deposited as shoreline sands along a coastal plain characterized by marine-dominant deltas (Catskill delta complex). These sandstones exhibit facies relationships between red beds and interbedded sandstones and shales that shift westward and eastward with offlap and onlap. Outcrop equivalents at Elkins, West Virginia, are correlated with the interval of Balltown to Fourth sands. Subsurface correlation indicates that maximum westward progradation occurred during deposition of the Gordon and Gordon Stray sands, and that transgression mainly characterized the younger Devonian sands of the Thirty-foot, Fifty-foot and Gantz. Regional correlations suggest that the Bradford-Balltown and Speechly (B sands of Pennsylvania Geological Survey) sands are better developed in northwestern Pennsylvania, whereas the Bayard through Gantz (D sands of Pennsylvania Geological Survey) sands are better developed in northern and central West Virginia, decreasing also in buildup toward southeastern West Virginia. The oil-bearing sandstones occur in strike trend (north-south) in north-central West Virginia connected by feeder channel sandstones with dip trends (east-west). The interpreted fluvial and tidal channels combine to represent distributary channels that supplied the sands to the barrier islands and delta front. Shoreline shifts, with regression and transgression of the ancient sea, caused corresponding changes in distal-fan accumulations with time.

  16. Proglumide exhibits delta opioid agonist properties.

    PubMed

    Rezvani, A; Stokes, K B; Rhoads, D L; Way, E L

    1987-01-01

    Recently, it was reported that proglumide, a cholecystokinin (CCK) antagonist, potentiates the analgetic effects of morphine and endogenous opioid peptides and reverses morphine tolerance by antagonizing the CCK system in the central nervous system of the rat. In order to provide additional insight into the mode of action of this agent, we assessed the effect of proglumide in the isolated guinea pig ileum and the mouse, rat and rabbit vas deferens. Furthermore, we studied the in vitro binding affinity of this substance to mouse brain synaptosomes. Our results show that proglumide inhibits, dose dependently, the electrically stimulated twitches in the mouse vas deferens and guinea pig ileum, but not in the rat or rabbit vas deferens. The inhibitory action of proglumide on the mouse vas deferens, but not on the guinea pig ileum, is antagonized by naloxone and by the selective delta-antagonist, ICI 174,864, in a competitive fashion. Other CCK antagonists were found to be devoid of such activity on the mouse vas deferens. In vitro binding studies showed that proglumide displaces D-ala-D-[leucine]5-enkephalin (DADLE), a delta agonist, but not ethylketocyclazocine (EKC), a preferentially selective kappa agonist. The effect of proglumide appeared to be elicited presynaptically since it did not alter the norepinephrine-induced contractions of the mouse vas deferens. Our results suggest that proglumide might exert its opiate-like effects by activation of delta-opioid receptors. PMID:3030338

  17. Delta: Data Reduction for Integrated Application Workflows.

    SciTech Connect

    Lofstead, Gerald Fredrick; Jean-Baptiste, Gregory; Oldfield, Ron A.

    2015-06-01

    Integrated Application Workflows (IAWs) run multiple simulation workflow components con- currently on an HPC resource connecting these components using compute area resources and compensating for any performance or data processing rate mismatches. These IAWs require high frequency and high volume data transfers between compute nodes and staging area nodes during the lifetime of a large parallel computation. The available network band- width between the two areas may not be enough to efficiently support the data movement. As the processing power available to compute resources increases, the requirements for this data transfer will become more difficult to satisfy and perhaps will not be satisfiable at all since network capabilities are not expanding at a comparable rate. Furthermore, energy consumption in HPC environments is expected to grow by an order of magnitude as exas- cale systems become a reality. The energy cost of moving large amounts of data frequently will contribute to this issue. It is necessary to reduce the volume of data without reducing the quality of data when it is being processed and analyzed. Delta resolves the issue by addressing the lifetime data transfer operations. Delta removes subsequent identical copies of already transmitted data during transfers and restores those copies once the data has reached the destination. Delta is able to identify duplicated information and determine the most space efficient way to represent it. Initial tests show about 50% reduction in data movement while maintaining the same data quality and transmission frequency.

  18. Quantitative expression patterns of peroxisome proliferator-activated receptor-{beta}/{delta} (PPAR{beta}/{delta}) protein in mice

    SciTech Connect

    Girroir, Elizabeth E.; Hollingshead, Holly E.; He Pengfei; Zhu Bokai; Perdew, Gary H.; Peters, Jeffrey M.

    2008-07-04

    The expression patterns of PPAR{beta}/{delta} have been described, but the majority of these data are based on mRNA data. To date, there are no reports that have quantitatively examined the expression of PPAR{beta}/{delta} protein in mouse tissues. In the present study, a highly specific PPAR{beta}/{delta} antibody was developed, characterized, and used to examine tissue expression patterns of PPAR{beta}/{delta}. As compared to commercially available anti-PPAR{beta}/{delta} antibodies, one of six polyclonal anti-PPAR{beta}/{delta} antibodies developed was significantly more effective for immunoprecipitation of in vitro-translated PPAR{beta}/{delta}. This antibody was used for quantitative Western blot analysis using radioactive detection methods. Expression of PPAR{beta}/{delta} was highest in colon, small intestine, liver, and keratinocytes as compared to other tissues including heart, spleen, skeletal muscle, lung, brain, and thymus. Interestingly, PPAR{beta}/{delta} expression was localized in the nucleus and RXR{alpha} can be co-immunoprecipitated with nuclear PPAR{beta}/{delta}. Results from these studies demonstrate that PPAR{beta}/{delta} expression is highest in intestinal epithelium, liver, and keratinocytes, consistent with significant biological roles in these tissues.

  19. Explanation of the {delta}{sub 5/2{sup -}}(1930) as a {rho}{delta} bound state

    SciTech Connect

    Gonzalez, P.; Oset, E.; Vijande, J.

    2009-02-15

    We use the {rho}{delta} interaction in the hidden gauge formalism to dynamically generate N* and {delta}* resonances. We show, through a comparison of the results from this analysis and from a quark model study with data, that the {delta}{sub 5/2{sup -}}(1930), {delta}{sub 3/2{sup -}}(1940), and {delta}{sub 1/2{sup -}}(1900) resonances can be assigned to {rho}{delta} bound states. More precisely the {delta}{sub 5/2{sup -}}(1930) can be interpreted as a {rho}{delta} bound state whereas the {delta}{sub 3/2{sup -}}(1940) and {delta}{sub 1/2{sup -}}(1900) may contain an important {rho}{delta} component. This interpretation allows for a solution of a long-standing puzzle concerning the description of these resonances in constituent quark models. In addition we also obtain degenerate J{sup P}=1/2{sup -},3/2{sup -},5/2{sup -} N* states but their assignment to experimental resonances is more uncertain.

  20. Treatment of Tourette syndrome with delta-9-tetrahydrocannabinol (delta 9-THC): no influence on neuropsychological performance.

    PubMed

    Müller-Vahl, Kirsten R; Prevedel, Heidrun; Theloe, Karen; Kolbe, Hans; Emrich, Hinderk M; Schneider, Udo

    2003-02-01

    Previous studies provide evidence that marijuana (Cannabis sativa) and delta-9-tetrahydrocannabinol (Delta(9)-THC), the major psychoactive ingredient of marijuana, respectively, are effective in the treatment of tics and behavioral problems in Tourette syndrome (TS). It, therefore, has been speculated that the central cannabinoid receptor system might be involved in TS pathology. However, in healthy marijuana users there is an ongoing debate as to whether the use of cannabis causes acute and/or long-term cognitive deficits. In this randomized double-blind placebo-controlled study, we investigated the effect of a treatment with up to 10 mg Delta(9)-THC over a 6-week period on neuropsychological performance in 24 patients suffering from TS. During medication and immediately as well as 5-6 weeks after withdrawal of Delta(9)-THC treatment, no detrimental effect was seen on learning curve, interference, recall and recognition of word lists, immediate visual memory span, and divided attention. Measuring immediate verbal memory span, we even found a trend towards a significant improvement during and after treatment. Results from this study corroborate previous data suggesting that in patients suffering from TS, treatment with Delta(9)-THC causes neither acute nor long-term cognitive deficits. Larger and longer-duration controlled studies are recommended to provide more information on the adverse effect profile of THC in patients suffering from TS. PMID:12589392

  1. Structural and magnetic properties of Nd{sub 2}Fe{sub 17-{delta}}Ga{sub {delta}} ({delta}{<=}2)

    SciTech Connect

    Girt, E.; Guillot, M.; Krishnan, Kannan M.; Altounian, Z.; Thomas, G.

    2000-05-01

    Magnetization measurements of Nd{sub 2}Fe{sub 17-{delta}}Ga{sub {delta}} ({delta}=0-2) show that the saturation magnetization, M{sub s}, decreases with an increase in Ga content from 40.4 {mu}{sub B}/f.u. for Nd{sub 2}Fe{sub 17} to 36.1 {mu}{sub B}/f.u. for Nd{sub 2}Fe{sub 15}Ga{sub 2} at 4.2 K. Neutron diffraction data at 25 K show that the magnetic moment of Fe depends on its crystallographic site and decreases in the order Fe(6c)>Fe(18f){>=}Fe(18h){>=}Fe(9d). The magnetic moments of Fe(9d), Fe(18f), and Fe(18h) are found to be practically independent of the Ga content. However, the magnetic moment of Fe(6c) decreases from 2.81(9) {mu}{sub B} in Nd{sub 2}Fe{sub 17} to 2.14(9) {mu}{sub B} in Nd{sub 2}Fe{sub 15}Ga{sub 2}. The decrease of the Fe(6c) moment clearly reduces the exchange interaction between Fe(6c)-Fe(6c) dumbbell pairs which explains the decrease in the anomalous thermal expansion with an increase in Ga concentration. The reduced Fe(6c)-Fe(6c) exchange interaction may also play an important role in increasing the Curie temperature, T{sub C}, with Ga content; T{sub C} increases from 327 K in Nd{sub 2}Fe{sub 17} to 535 K in Nd{sub 2}Fe{sub 15}Ga{sub 2}. (c) 2000 American Institute of Physics.

  2. Analysis, testing, and evaluation of faulted and unfaulted Wye, Delta, and open Delta connected electromechanical actuators

    NASA Technical Reports Server (NTRS)

    Nehl, T. W.; Demerdash, N. A.

    1983-01-01

    Mathematical models capable of simulating the transient, steady state, and faulted performance characteristics of various brushless dc machine-PSA (power switching assembly) configurations were developed. These systems are intended for possible future use as primemovers in EMAs (electromechanical actuators) for flight control applications. These machine-PSA configurations include wye, delta, and open-delta connected systems. The research performed under this contract was initially broken down into the following six tasks: development of mathematical models for various machine-PSA configurations; experimental validation of the model for failure modes; experimental validation of the mathematical model for shorted turn-failure modes; tradeoff study; and documentation of results and methodology.

  3. Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition

    SciTech Connect

    Xu, R; Wong, J; Zshack, P; Hong, H; Chiang, T

    2007-09-13

    Plutonium and its alloys exhibit complex phase diagrams that imply anomalous lattice dynamics near phase stability boundaries. Specifically, the TA [111] phonon branch in Ga-stabilized {delta}-Pu at room temperature shows a pronounced soft mode at the zone boundary, which suggests a possible connection to the martensitic transformation from the fcc {delta}-phase to the monoclinic {alpha}{prime}-phase at low temperatures. This work is a study of the lattice dynamics of this system by x-ray thermal diffuse scattering. The results reveal little temperature dependence of the phonon frequencies, thus indicating that kinetic phonon softening is not responsible for this phase transition.

  4. Development of rules for single-line fault diagnosis in delta-delta connected distribution systems

    SciTech Connect

    Momoh, J.A.; Dias, L.G.; Thor, T.; Laird, D.N.

    1994-12-31

    Single-line fault diagnosis in delta-delta connected distribution systems suffers due to the low fault currents associated with such faults. Simulation tests on this type of system reveals that rule based decision support can be used of such diagnosis. This paper describes the development of rules for single-line fault diagnosis utilizing simulation test results. The key parameters used are the voltage magnitude of each phase at the bus bar and the currents on the feeders including their sequence components.

  5. Dual regulation of the {delta}Np63 transcriptional activity by {delta}Np63 in human nasopharyngeal carcinoma cell

    SciTech Connect

    Chu, W.-K.; Lee, K.-C.; Chow, S.-E.; Chen, J.-K. . E-mail: jkc508@mail.cgu.edu.tw

    2006-04-21

    p63 splicing variants lacking NH{sub 2}-terminal transactivating domain, known as {delta}Np63, are thought to antagonize p53 and p63 functions and are suggested to play roles in keratinocyte differentiation. Here, we show that {delta}Np63 has a dual-regulatory effect on the activity of its own promoter in NPC-076 cell. Down-regulation of the transcriptional activity is observed when {delta}Np63 is present in low levels. In contrast, up-regulation of {delta}Np63 transcriptional activity is observed when {delta}Np63 is expressed at higher levels. The down-regulation effect is abolished when the p53-binding site of the {delta}Np63 promoter is mutated. In sharp contrast, similar mutation does not affect the up-regulation of the {delta}Np63 transcriptional activity under the same experimental conditions. Further study shows that the up-regulation is correlated with the activation of the STAT3, as the blockade of STAT3 nuclear translocation abolishes the up-regulation by {delta}Np63. Thus, {delta}Np63 exerts a bidirectional regulation of the {delta}Np63 transcriptional activity in NPC-076 cell.

  6. Measuring Delta Progradation Using Delta Front Flow Patterns: A New Method of Remote Imagery Analysis on the Wax Lake Delta, Louisiana, U.S.A.

    NASA Astrophysics Data System (ADS)

    Estep, J. D.; Shaw, J.; Edmonds, D. A.

    2015-12-01

    Quantifying the progradation of the Wax Lake Delta (WLD), a sub-delta of the Mississippi River Delta, can lend valuable insight into coastal land-building patterns. Previous studies of WLD progradation have relied on subaerially-exposed land for indicating delta extent, but an inherent problem with this method lies in the high variability of exposed land due to vegetative, hydrologic, and atmospheric fluctuations. By mapping water surface films observed in remote imagery which form streaklines along flow paths in the delta, we show that the shallow delta front flow patterns are relatively unaffected by short term water level changes and can be used to evaluate WLD progradation over time. Remotely sensed imagery from multiple sources (infrared aerial photography, SPOT, UAVSAR) spanning from 1988 to 2015 was used to map streaklines from which we calculate a flow direction divergence field across the delta. Measuring the translation of this field through time, such as areas containing extreme divergence values along the delta front, quantifies the progradation over the time elapsed. Preliminary measurements of WLD progradation were subdivided into the eastern, southern, and western thirds of the delta. The eastern third prograded at 110 ±20m/yr from 1988 - 1997, 100 ±40m/yr from 1997 - 2002, and then remained relatively constant to 2015. The southern third prograded at 130 ±20m/yr from 1988 - 1997, 200 ±40m/yr from 1997 - 2002, and remained relatively constant to 2015. The western third prograded at 130 ±30m/yr from 1988 - 1997, 220 ±60 m from 1997 - 2002, and then remained relatively constant from 2002 - 2015. Also of note is the retrogradation on the average of 700 ±400m observed from January to August, 1992 which we interpret as being caused by the impact of Hurricane Andrew. The streakline methodology of evaluating WLD progradation could provide new methods for analysis of land change in other deltas around the world.

  7. LABORATORY EVALUATION OF THE DELTA Q TEST FOR DUCT LEAKAGE

    SciTech Connect

    ANDREWS,J.W.

    2003-05-01

    Using a residential-size duct system in a controlled laboratory setting, the repeatability and accuracy of the Delta Q test for air leakage in residential duct systems have been measured. More than 100 Delta Q tests were performed. These were compared with results using fan pressurization and also with results of a procedure (Delta Q Plus) that uses leakage hole-size information to select the leakage pressures to be used in the Delta Q algorithm. The average error in supply or return leakage for the fan-pressurization test was 6.4% of system fan flow. For the Delta Q test it was 3.4% of fan flow, while for Delta Q Plus it was 1.9% of fan flow.

  8. Tidal river dynamics: Implications for deltas

    NASA Astrophysics Data System (ADS)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  9. On \\delta-derivations of n-ary algebras

    NASA Astrophysics Data System (ADS)

    Kaygorodov, Ivan B.

    2012-12-01

    We give a description of \\delta-derivations of (n+1)-dimensional n-ary Filippov algebras and, as a consequence, of simple finite-dimensional Filippov algebras over an algebraically closed field of characteristic zero. We also give new examples of non-trivial \\delta-derivations of Filippov algebras and show that there are no non-trivial \\delta-derivations of the simple ternary Mal'tsev algebra M_8.

  10. Delta Doping High Purity CCDs and CMOS for LSST

    NASA Technical Reports Server (NTRS)

    Blacksberg, Jordana; Nikzad, Shouleh; Hoenk, Michael; Elliott, S. Tom; Bebek, Chris; Holland, Steve; Kolbe, Bill

    2006-01-01

    A viewgraph presentation describing delta doping high purity CCD's and CMOS for LSST is shown. The topics include: 1) Overview of JPL s versatile back-surface process for CCDs and CMOS; 2) Application to SNAP and ORION missions; 3) Delta doping as a back-surface electrode for fully depleted LBNL CCDs; 4) Delta doping high purity CCDs for SNAP and ORION; 5) JPL CMP thinning process development; and 6) Antireflection coating process development.

  11. Identification and characterization of Delta12, Delta6, and Delta5 Desaturases from the green microalga Parietochloris incisa.

    PubMed

    Iskandarov, Umidjon; Khozin-Goldberg, Inna; Cohen, Zvi

    2010-06-01

    The freshwater microalga Parietochloris incisa accumulates, under nitrogen starvation, large amounts of triacylglycerols containing approximately 60% of the omega6 very long-chain polyunsaturated fatty acid (VLC-PUFA), arachidonic acid. Based on sequence homology, we isolated three cDNA sequences from P. incisa, designated PiDesD12, PiDesD6, PiDesD5. The deduced amino acid sequences of the three genes contained three conserved histidine motifs; the front-end desaturases, PiDes6 and PiDes5, contained a fused N-terminal cytochrome b5 domain. By functional characterization in the yeast Saccharomyces cerevisiae, we confirmed that PiDesD6, PiDesD5 cDNA encode membrane bound desaturases with Delta6, and Delta5 activity, respectively. Both PiDes6 and PiDes5 can indiscriminately desaturate both omega6 and omega3 substrates. A phylogenetic analysis showed that the three genes were homologous to the corresponding desaturases from green microalgae and lower plants that were functionally characterized. Quantitative real-time PCR revealed the concerted expression pattern of all three genes in P. incisa cells subjected to nitrogen starvation, featuring maximum expression level on day 3 of starvation, corresponding to the sharpest increase in the share of arachidonic acid. PMID:20467827

  12. INSAT-1A launch on Delta

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The INSAT-1A, the first in a series of 12 transponder communications satellites developed for India, is described as well as the launch plans. The launch vehicle will be the Delta 3910 configuration which incorporates an extended long tank Thor booster, nine Castor IV strap-on motors, a TR-201 second stage, and an 8 foot fairing. The satellite will be placed in a suborbital trajectory. A DAM-D stage will then thrust it into a synchronous transfer orbit. An apogee kick motor will be fired to circularize its orbit at a geosynchronous altitude of 19,300 nautical miles.

  13. Shoreface morphodynamics along the Danube Delta coast

    NASA Astrophysics Data System (ADS)

    Tatui, Florin; Vespremeanu-Stroe, Alfred

    2015-04-01

    The shoreface has an important long-term contribution to the coastal sediment budget as it behaves as either a sink or source of sediment from/to the active zone (Hinton and Nicholls, 2007). Hence, it modulates the long-term shoreline movement. However, the shoreface behaviour remains poorly understood and such studies are scarce especially because of the lack of extensive long-term good-quality data. The objective of this study is to examine and explain the shoreface morphodynamics along the Danube Delta coast. The shoreface morphodynamics has been investigated over the medium- and large-scales (decades to centuries). This is a wave-dominated, low-lying coastline interrupted by river mouths and, sometimes, by engineering structures (jetties). This work uses historical and modern maps (since 1856) and bathymetrical measurements (2008 and 2014) extending along the whole Danube Delta coast (both Romanian and Ukrainian sectors) to water depths of approximately 20 m; sectorial seasonal and annual bathymetries of the upper shoreface (2003 - 2014); LIDAR data (2011), recent high resolution satellite images, ortophotos and GPS surveys for shoreline extraction, which were comparatively analysed (volume changes, profile to profile evolution) by means of GIS techniques in order to explain the morphological and volumetric evolution of the shoreface. The large scale coastal behaviour of Danube Delta coast (expressed in terms of shoreface sediment volume and spatial distribution pattern of cells) is linked to climatic forcings (storminess), Danube river sediment supply changes, longshore sediment transport distribution and impact of hard coastal engineering structures. Significant increase of shoreface volume in the last century is related to active deltaic lobes (Chilia) or developing barrier islands (Sacalin), while decreasing shoreface volumes are related to the presence of Sulina jetties which blocked the longshore sediment transport and induced severe erosion downdrift. In

  14. International Year of Deltas 2013: A proposal

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, Efi; Syvitski, James; Paola, Chris; Hoanh, Chu Thai; Tuong, Phuc; Vörösmarty, Charles; Kremer, Hartwig; Brondizio, Eduardo; Saito, Yoshiki; Twilley, Robert

    2011-10-01

    Marine and lacustrine deltas around the world are economic and environmental hot spots. They occupy approximately 1% of the Earth's land area but are home to more than 500 million people—a population density more than 10 times the world average [Ericson et al., 2006]—all within 5 meters of sea level [Overeem and Syvitski, 2009]. This high density is supported by high productivity, rich biodiversity, and transport along a network of waterways. Yet deltaic systems are some of the world's most delicate and vulnerable natural systems, residing at the boundary between land and water, and are subject to upstream human control, local resource exploration, and climatic impacts.

  15. Delta Alerts: Changing Outcomes in Geriatric Trauma.

    PubMed

    Wiles, Lynn L; Day, Mark D; Harris, LeAnna

    2016-01-01

    Geriatric trauma patients (GTPs) suffering minor injuries have suboptimal outcomes compared with younger populations. Patients 65 years or older account for 10% of all traumas but 28% of all trauma deaths. This trauma center established a third tier trauma alert specifically targeting GTPs at risk for poor outcomes. A Delta Alert is activated when GTPs suffer injuries that fall outside traditional trauma alert guidelines. Early identification and treatment of injuries and expedited referral to specialty groups have improved our GTPs' outcomes including decreased mortality and length of stay and increased percentage of GTPs who are discharged home. PMID:27414140

  16. Delta-92 Telesat-A operations summary

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Telesat-A, which is the first of the Canadian Telesat satellites to be launched for the domestic satellite communications system is described. The launch vehicle, designated Delta-92 consists of a DSV 3p-11 extended long tank first stage with an MB-3 engine, augmented by low-drag Castor 2 solid motors. The spacecraft has a spin-stabilized electronic system powered by 23,000 solar cells, with sufficient on-board battery capability to provide full capacity power during eclipse of the solar cells. A 60-inch wide circular directional antenna which remains constantly aimed at Canada is included.

  17. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A Boeing Delta 7326 rocket with two solid rocket boosters attached sits on Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. Delta's origins go back to the Thor intermediate-range ballistic missile, which was developed in the mid-1950s for the U.S. Air Force. The Thor -- a single-stage, liquid-fueled rocket -- later was modified to become the Delta launch vehicle. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Final assembly takes place at the Boeing facility in Pueblo, Colo. The Delta 7236, which has three solid rocket boosters and a Star 37 upper stage, will launch Deep Space 1, the first flight in NASA's New Millennium Program. It is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  18. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    - A solid rocket booster is maneuvered into place for installation on the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. Delta's origins go back to the Thor intermediate-range ballistic missile, which was developed in the mid-1950s for the U.S. Air Force. The Thor -- a single-stage, liquid-fueled rocket -- later was modified to become the Delta launch vehicle. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Final assembly takes place at the Boeing facility in Pueblo, Colo. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  19. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    (Left) A solid rocket booster is lifted for installation onto the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. Delta's origins go back to the Thor intermediate-range ballistic missile, which was developed in the mid-1950s for the U.S. Air Force. The Thor -- a single-stage, liquid-fueled rocket -- later was modified to become the Delta launch vehicle. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Final assembly takes place at the Boeing facility in Pueblo, Colo. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  20. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A solid rocket booster (left) is raised for installation onto the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. Delta's origins go back to the Thor intermediate-range ballistic missile, which was developed in the mid-1950s for the U.S. Air Force. The Thor -- a single-stage, liquid-fueled rocket -- later was modified to become the Delta launch vehicle. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Final assembly takes place at the Boeing facility in Pueblo, Colo. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  1. Upper-division student difficulties with the Dirac delta function

    NASA Astrophysics Data System (ADS)

    Wilcox, Bethany R.; Pollock, Steven J.

    2015-06-01

    The Dirac delta function is a standard mathematical tool that appears repeatedly in the undergraduate physics curriculum in multiple topical areas including electrostatics, and quantum mechanics. While Dirac delta functions are often introduced in order to simplify a problem mathematically, students still struggle to manipulate and interpret them. To characterize student difficulties with the delta function at the upper-division level, we examined students' responses to traditional exam questions and a standardized conceptual assessment, and conducted think-aloud interviews. Our analysis was guided by an analytical framework that focuses on how students activate, construct, execute, and reflect on the Dirac delta function in the context of problem solving in physics. Here, we focus on student difficulties using the delta function to express charge distributions in the context of junior-level electrostatics. Common challenges included invoking the delta function spontaneously, translating a description of a charge distribution into a mathematical expression using delta functions, integrating 3D or non-Cartesian delta function expressions, and recognizing that the delta function can have units. We also briefly discuss implications of these difficulties for instruction.

  2. Investigation of television transmission using adaptive delta modulation principles

    NASA Technical Reports Server (NTRS)

    Schilling, D. L.

    1976-01-01

    The results are presented of a study on the use of the delta modulator as a digital encoder of television signals. The computer simulation of different delta modulators was studied in order to find a satisfactory delta modulator. After finding a suitable delta modulator algorithm via computer simulation, the results were analyzed and then implemented in hardware to study its ability to encode real time motion pictures from an NTSC format television camera. The effects of channel errors on the delta modulated video signal were tested along with several error correction algorithms via computer simulation. A very high speed delta modulator was built (out of ECL logic), incorporating the most promising of the correction schemes, so that it could be tested on real time motion pictures. Delta modulators were investigated which could achieve significant bandwidth reduction without regard to complexity or speed. The first scheme investigated was a real time frame to frame encoding scheme which required the assembly of fourteen, 131,000 bit long shift registers as well as a high speed delta modulator. The other schemes involved the computer simulation of two dimensional delta modulator algorithms.

  3. The effect of interference on delta modulation encoded video signals

    NASA Technical Reports Server (NTRS)

    Schilling, D. L.

    1979-01-01

    The results of a study on the use of the delta modulator as a digital encoder of television signals are presented. The computer simulation was studied of different delta modulators in order to find a satisfactory delta modulator. After finding a suitable delta modulator algorithm via computer simulation, the results are analyzed and then implemented in hardware to study the ability to encode real time motion pictures from an NTSC format television camera. The effects were investigated of channel errors on the delta modulated video signal and several error correction algorithms were tested via computer simulation. A very high speed delta modulator was built (out of ECL logic), incorporating the most promising of the correction schemes, so that it could be tested on real time motion pictures. The final area of investigation concerned itself with finding delta modulators which could achieve significant bandwidth reduction without regard to complexity or speed. The first such scheme to be investigated was a real time frame to frame encoding scheme which required the assembly of fourteen, 131,000 bit long shift registers as well as a high speed delta modulator. The other schemes involved two dimensional delta modulator algorithms.

  4. Elwha River Delta: Geomorphology of a Mixed-Sediment Beach

    NASA Astrophysics Data System (ADS)

    George, D. A.; Warrick, J. J.

    2007-12-01

    The Elwha River drains the Olympic Peninsula of Washington and forms a mixed grain-size delta in the Strait of Juan de Fuca. The Elwha River has been dammed for almost a century, and a pending dam removal project is expected to reconnect upstream sediment sources to the river mouth. Topographic and grain-size mapping of the delta during 1939-2007 is synthesized and the geomorphology and shoreline changes of this system are described. Data sources include historical aerial photographs, airborne LIDAR, semiannual RTK DGPS topographic surveys and grain-size analyses from digital photographs. The delta is divided into three geomorphic regions: west delta, river mouth and east delta. The river mouth is the most complex region due to the river channel movement, side-channels, and bars immediately offshore of the mouth. The east and west delta differ in beach profile and shoreline change rates. The west delta is steep, cuspate and lacks a low-tide terrace. Further, the west delta has exhibited little semi-annual or inter-annual shoreline change. In contrast, the east delta has a steep foreshore, flat low tide terrace that is dominated by cobble, and a consistent trend of erosion during the surveys. These observations can be used to track coastal changes following dam removal on the Elwha River..

  5. Inferring heterogeneity in aquitards using high-resolution deltaD and delta18O profiles.

    PubMed

    Hendry, M Jim; Wassenaar, L I

    2009-01-01

    Vertical depth profiles of pore water isotopes (deltaD and delta18O) in clay-rich aquitards have been used to show that solute transport is dominated by molecular diffusion, to define the timing of geologic events, and to estimate vertical hydraulic conductivity. The interpretation of the isotopic profiles in these studies was based on pore water samples collected from piezometers installed in nests (typically 4 to 15 piezometers) over depths of 10 to 80 m. Data from piezometer nests generally have poor vertical resolution (meters), raising questions about their capacity to reveal the impact of finer scale heterogeneities such as permeable sand bodies or fractured till zones on solute transport. Here, we used high-resolution (30-cm) depth profiles of deltaD and delta18O from two continuously cored boreholes in a till aquitard to provide new insights into the effects of sand bodies on solute transport. High-resolution core-derived profiles indicate that such heterogeneities can cause major deviations from one-dimensional diffusion profiles. Further, comparison of piezometer-measured values with best-fit diffusion trends shows subtle deviations, suggesting the presence of heterogeneities that should not be ignored. High-resolution profiles also more clearly defined the contact between the highly fractured oxidized zone and the underlying unoxidized zone than the piezometers. PMID:19735307

  6. Validating methods for measuring delta18O and delta13C in otoliths from freshwater fish.

    PubMed

    Guiguer, K R R A; Drimmie, R; Power, M

    2003-01-01

    The ability of the phosphoric acid digestion technique to extract carbon dioxide from biogenic carbonates and reliably reproduce delta(18)O and delta(13)C signatures from standard reference materials (NBS-18, NBS-19) was tested and shown to produce accurate, unbiased measurements of non-biologic materials. The effects of roasting preparation methods commonly reported when analyzing biogenic carbonates were also tested in a series of experiments using reference standards and otoliths obtained from aquacultured Arctic charr and rainbow trout. Roasting had no effect on the isotope measurement of reference standards. No significant differences between mean oxygen isotope signatures from paired experiments with roasted and non-roasted fish otoliths were found. However, otolith oxygen isotope measurements were significantly enriched in comparison to rearing water-based measurements for both species. Agreement between expected isotopic equilibrium and measured otolith delta(18)O values varied as a function of roasting temperature and between species. Criteria for the selection of appropriate roasting temperatures are suggested and favour 350 degrees C in freshwater fish where unbiased estimates of average rearing water temperatures and known differences in rearing temperatures were obtained. Carbon isotopic disequilibria were observed for both species. A mixing model analysis established differences in the percentage of metabolically derived carbon in studied otoliths, with Arctic charr deriving a greater proportion of otolith delta(13)C from metabolism as a result of higher metabolic rates. PMID:12590395

  7. Hydraulic Geometry of a tidally influenced delta channel network: the Mahakam Delta, East Kalimantan, Indonesia

    NASA Astrophysics Data System (ADS)

    Sassi, M.; Hoitink, A.; de Brye, B.; Deleersnijder, E.

    2011-12-01

    Hydraulic Geometry (HG) refers to relations between the characteristics of channels in a network, including mean depth, width, and bed slope, and the discharge conveyed by the channel during bank-full conditions. HG relations are of fundamental importance to water management in channel networks, and they bear an interesting relation with geomorphology. River delta channel networks typically scale according to HG relations such as log(A) ~ p*log(Q), where A is channel cross sectional area, Q water discharge, and the exponent p is in between 0.8 and 1.2. In tidal networks, the tidal prism or tidal discharge can be used, instead of a discharge with a constant frequency of occurrence. In the tidal case, the exponent often shows the same range of variation. Tidal rivers are intrinsically complex, as tidal propagation is influenced by river discharge and vice-versa. Consequently, channel geometry in tidally influenced river deltas may show a mixed scaling behavior of river and tidal channel networks, as the channel forming discharges may both be of river and tidal origin. In tidal regions, the tidal dynamics may lead to a cyclic variation in water discharge distribution at bifurcations, readily affecting HG relations. We present results from the Mahakam delta channel network in Indonesia, a tide-river dominated delta which has been prograding for 60 km over the last 5000 years. Bathymetric surveys were conducted over the distributary network and connected tidal channels. Based on a geomorphic analysis of the present distributary network, we show that channel geometry of the fluvial distributary network scales with bifurcation order. The bifurcation order does not feature a clear relation with bifurcate branch length or bifurcate width ratio, as in the case of river deltas. HG relations of the area of selected cross-sections are well represented by the tidal prism or by the river discharge, when scaled with the bifurcation order. Numerical simulations show that river

  8. Squeaking and microcracks in a delta-delta ceramic coupling: pin-on-disc study.

    PubMed

    Fukui, Kiyokazu; Kaneuji, Ayumi; Matsumoto, Tadami; Shintani, Kazuhiro

    2016-04-01

    There is a rising concern about squeaking in ceramic-on-ceramic total hip arthroplasty (THA). In pin-on-disc testing of a delta-delta coupling, we reproduced squeaking and observed microcracks on worn surfaces. We used a pin-on-disc machine and made discs and pins by cutting delta ceramic to a diameter of 40 mm (D-D). Cross-linked polyethylene was used for a comparison disc (D-P). We performed the same test using another D-D coupling specimen to confirm reproducibility. Squeaking in the D-D specimen was reproduced in wet conditions, though it was not found in the D-P specimen. Fast Fourier transform analysis showed a peak frequency for squeaking of 2794 Hz. The noise occurred at about 6.6 km of sliding distance. Scanning electron microscopy revealed that the worn surface of the pin in D-D at 10.8 km of sliding distance had some microcracks. However, there was no obvious damage to the worn surface of the pin in D-P at the same sliding distance. We confirmed the reproducibility of these findings, obtaining similar results, including squeaking, from another D-D coupling specimen. Our findings show that squeaking may occur in THA using delta ceramic bearings even if implants are placed to avoid extra-articular impingement of the femoral neck. Although the clinical relevance of microcracks is unknown, they may affect long-term outcomes in THA using delta ceramic bearings. PMID:26971327

  9. Do river deltas in east India retreat? A case of the Krishna Delta

    NASA Astrophysics Data System (ADS)

    Gamage, Nilantha; Smakhtin, Vladimir

    2009-02-01

    The construction of multiple dams and barrages in many Indian River basins over the last few decades significantly reduced river flow to the sea and affected the sediment regime. More reservoir construction is planned through the proposed National River Linking Project (NRLP), which will transfer massive amounts of water from the North to the South of India. The impacts of these developments on fertile and ecologically sensitive deltaic environments are poorly understood and quantified at present. In this paper an attempt is made to identify, locate and quantify coastal erosion and deposition processes in one of the major river basins in India—the Krishna—using a time series of Landsat images for 1977, 1990 and 2001 with a spatial resolution ranging from 57.0 m to 28.5 m. The dynamics of these processes are analyzed together with the time series of river flow, sediment discharge and sediment storage in the basin. Comparisons are made with similar processes identified and quantified earlier in the delta of a neighboring similarly large river basin—the Godavari. The results suggest that coastal erosion in the Krishna Delta progressed over the last 25 years at the average rate of 77.6 ha yr - 1 , dominating the entire delta coastline and exceeding the deposition rate threefold. The retreat of the Krishna Delta may be explained primarily by the reduced river inflow to the delta (which is three times less at present than 50 years ago) and the associated reduction of sediment load. Both are invariably related to upstream reservoir storage development.

  10. Status Of The Synchrotron Light Source DELTA

    SciTech Connect

    Berges, U.; Friedl, J.; Hartmann, P.; Schirmer, D.; Schmidt, G.; Sternemann, C.; Tolan, M.; Weis, T.; Westphal, C.; Wille, K.

    2004-05-12

    The Dortmund Electron Accelerator DELTA, located at the University of Dortmund, changed its scope during the last years into a 1.5 GeV synchrotron light source. DELTA is now operated for 3000 h per year including 2000 h dedicated beam time for synchrotron radiation use and 1000 h for machine physics, optimization and maintenance. The status of the accelerator complex is presented together with the beam operation, the installation and commissioning of beamlines and insertion devices. To serve user demands of photon energies up to more than 10 keV a 5.3 T superconducting asymmetric multipole wiggler (SAW) with a critical energy of 7.9 keV has been installed serving three beamlines in the hard X-ray regime with also circular polarization. Two undulator beamlines for photon energies between 5 and 400 eV (U250) and between 55 and 1500 eV (U55) and several dipole beamlines up to 200 eV are under operation. The construction and operation of the different beamlines is done by various universities and laboratories in Nordrhein-Westfalen.

  11. Niger delta deepwater region petroleum potential assessment

    SciTech Connect

    Thomas, D.

    1995-12-18

    On behalf of the Nigerian Ministry of Petroleum and Natural Resources some 23,000 km of high quality 192 channel, 96 fold seismic, and associated gravity and magnetic data were acquired by TGSI-Mabon Geophysical Co. and made available to the industry in 1991. These data were collected over all deepwater blocks in conjunction with the planned 1993 license round. Later, during 1993 and 1994 TGSI with Mabon Ltd. and Stratum Petroleum Services extended the program onto the shelf (7,000 km) and into the ultra deepwater areas (6,400 km), making possible modern studies of the entire offshore delta complex. In assessing the petroleum potential of an undrilled region, it is useful to refer to analogous basins or provinces already with histories of hydrocarbon exploration and discovery. With this in mind, and using limited data from the already drilled areas of Nigeria offshore, the adjacent West Africa salt basin and Brazil in particular, an attempt is made to discuss the hydrocarbon habitat of the undrilled Niger delta deepwater offshore sedimentary sequences.

  12. Multidecadal Fluvial Sediment Fluxes to Deltas under Environmental Change Scenarios

    NASA Astrophysics Data System (ADS)

    Dunn, Frances; Darby, Stephen; Nicholls, Robert

    2016-04-01

    Sediment delivery is vital to sustain delta environments on which over half a billion people live worldwide. Due to factors such as subsidence and sea level rise, deltas sink relative to sea level if sediment is not delivered to and retained on their surfaces. Deltas which sink relative to sea level experience flooding, land degradation and loss, which endangers anthropogenic activities and populations. The future of fluvial sediment fluxes, a key mechanism for sediment delivery to deltas, is uncertain due to complex environmental changes which are predicted to occur over the coming decades. This research investigates fluvial sediment fluxes under environmental changes in order to assess the sustainability of delta environments under potential future scenarios up to 2100. Global datasets of climate change, reservoir construction, and population and GDP as proxies for anthropogenic influence through land use changes are used to drive the catchment numerical model WBMsed, which is being used to investigate the effects of these environmental changes on fluvial sediment delivery. This process produces fluvial sediment fluxes under multiple future scenarios which will be used to assess the future sustainability of a selection of 8 vulnerable deltas, although the approach can be applied to deltas worldwide. By modelling potential future scenarios of fluvial sediment flux, this research contributes to the prognosis for delta environments. The future scenarios will inform management at multiple temporal scales, and indicate the potential consequences for deltas of various anthropogenic activities. This research will both forewarn managers of potentially unsustainable deltas and indicate those anthropogenic activities which encourage or hinder the creation of sustainable delta environments.

  13. 78 FR 21491 - DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ... ADMINISTRATION DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that DeltaPoint Capital IV, L.P. and DeltaPoint Capital IV (New York), L.P., 45 East Avenue, 6th...

  14. The Concentration Dependence of the (Delta)s Term in the Gibbs Free Energy Function: Application to Reversible Reactions in Biochemistry

    ERIC Educational Resources Information Center

    Gary, Ronald K.

    2004-01-01

    The concentration dependence of (delta)S term in the Gibbs free energy function is described in relation to its application to reversible reactions in biochemistry. An intuitive and non-mathematical argument for the concentration dependence of the (delta)S term in the Gibbs free energy equation is derived and the applicability of the equation to…

  15. Emerging leadership from communities in the Lower Mississippi Delta (LMD)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Delta NIRI (Nutrition Intervention Research Initiative) team has conducted several research studies in the Lower Mississippi Delta (LMD) region employing the community-based participatory research (CBPR) model. Our collaborative work in the LMD focuses on interventions conducted in each of our c...

  16. Upper-Division Student Difficulties with the Dirac Delta Function

    ERIC Educational Resources Information Center

    Wilcox, Bethany R.; Pollock, Steven J.

    2015-01-01

    The Dirac delta function is a standard mathematical tool that appears repeatedly in the undergraduate physics curriculum in multiple topical areas including electrostatics, and quantum mechanics. While Dirac delta functions are often introduced in order to simplify a problem mathematically, students still struggle to manipulate and interpret them.…

  17. Delta: the First Pion Nucleon Resonance - Its Discovery and Applications

    DOE R&D Accomplishments Database

    Nagle, D. E.

    1984-07-01

    It is attempted to recapture some of the fun and excitement of the pion-scattering work that led to the discovery of what is now called the delta particle. How significant this discovery was became apparent only gradually. That the delta is alive today and thriving at Los Alamos (as well as other places) is described.

  18. 1. Launch facility, delta 6, approach road and gate, pole ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Launch facility, delta 6, approach road and gate, pole marking the hardened intersite cable system in right center, commercial power pole outside fence in left center, view towards south - Ellsworth Air Force Base, Delta Flight, Launch Facility D-6, 4 miles north of Badlands National Park Headquarters, 4.5 miles east of Jackson County line on county road, Interior, Jackson County, SD

  19. The [delta]f algorithm for beam dynamics

    SciTech Connect

    Koga, J.; Tajima, T.

    1993-05-01

    An algorithm is developed to study particle dynamics of beams including collective interaction with high accuracy and low noise. Particle dynamics with collective interactions is treated through particle simulation, where the main or average distribution f[sub 0] and the deviation away from it [delta]f are separately followed. The main distribution f[sub 0] is handled by an analytic equilibrium solution and the perturbation away from it [delta]f is followed by the method of characteristics. We call this the [delta]f algorithm. We specifically model a synchrotron collider which includes the collision section where collective effects of collisions are simulated by this [delta]f algorithm and the rest of the collider where single particle dynamics are treated by simple harmonic transport. The most important target of this simulation is to understand and predict the long-time behavior of the beam luminosity and lifetime. The [delta]f method allows the study the effect of small perturbations over long timescales on beam lifetime by eliminating the numerical noise problem inherent in Particle-in-Cell techniques. In the [delta]f code using the reference parameters of the SSC (Superconducting Super Collider), beam blow-up near resonances and oscillations in the tune shift, [Delta][nu], far from resonances are observed. In studying long timescale particle diffusion in the phase space of the beams away from resonances, the [delta]f code performance is compared with a tracking code which does not incorporate collective interaction.

  20. The {delta}f algorithm for beam dynamics

    SciTech Connect

    Koga, J.; Tajima, T.

    1993-05-01

    An algorithm is developed to study particle dynamics of beams including collective interaction with high accuracy and low noise. Particle dynamics with collective interactions is treated through particle simulation, where the main or average distribution f{sub 0} and the deviation away from it {delta}f are separately followed. The main distribution f{sub 0} is handled by an analytic equilibrium solution and the perturbation away from it {delta}f is followed by the method of characteristics. We call this the {delta}f algorithm. We specifically model a synchrotron collider which includes the collision section where collective effects of collisions are simulated by this {delta}f algorithm and the rest of the collider where single particle dynamics are treated by simple harmonic transport. The most important target of this simulation is to understand and predict the long-time behavior of the beam luminosity and lifetime. The {delta}f method allows the study the effect of small perturbations over long timescales on beam lifetime by eliminating the numerical noise problem inherent in Particle-in-Cell techniques. In the {delta}f code using the reference parameters of the SSC (Superconducting Super Collider), beam blow-up near resonances and oscillations in the tune shift, {Delta}{nu}, far from resonances are observed. In studying long timescale particle diffusion in the phase space of the beams away from resonances, the {delta}f code performance is compared with a tracking code which does not incorporate collective interaction.

  1. Gene sharing by delta-crystallin and argininosuccinate lyase.

    PubMed Central

    Piatigorsky, J; O'Brien, W E; Norman, B L; Kalumuck, K; Wistow, G J; Borras, T; Nickerson, J M; Wawrousek, E F

    1988-01-01

    The lens structural protein delta-crystallin and the metabolic enzyme argininosuccinate lyase (ASL; L-argininosuccinate arginine-lyase, EC 4.3.2.1) have striking sequence similarity. We have demonstrated that duck delta-crystallin has enormously high ASL activity, while chicken delta-crystallin has lower but significant activity. The lenses of these birds had much greater ASL activity than other tissues, suggesting that ASL is being expressed at unusually high levels as a structural component. In Southern blots of human genomic DNA, chicken delta 1-crystallin cDNA hybridized only to the human ASL gene; moreover, the two chicken delta-crystallin genes accounted for all the sequences in the chicken genome able to cross-hybridize with a human ASL cDNA, with preferential hybridization to the delta 2 gene. Correlations of enzymatic activity and recent data on mRNA levels in the chicken lens suggest that ASL activity depends on expression of the delta 2-crystallin gene. The data indicate that the same gene, at least in ducks, encodes two different functions, an enzyme (ASL) and a structural protein (delta-crystallin), although in chickens specialization and separation of functions may have occurred. Images PMID:3368457

  2. Antinociceptive activity of Delta9-tetrahydrocannabinol non-ionic microemulsions.

    PubMed

    Lazzari, P; Fadda, P; Marchese, G; Casu, G L; Pani, L

    2010-06-30

    Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent of Cannabis sativa L., has been widely studied for its potential pharmaceutical application in the treatment of various diseases and disturbs. This sparingly soluble terpeno-phenolic compound is not easy to handle and to be formulated in pharmaceutical preparations. The aim of this work was to develop a stable aqueous Delta(9)-THC formulation acceptable for different ways of administration, and to evaluate the therapeutic properties of the new Delta(9)-THC based preparation for pain treatment. Due to the thermodynamic stability and advantages of microemulsion based systems, the study was focused on the identification of aqueous microemulsion based systems containing Delta(9)-THC. Oil in water Delta(9)-THC microemulsions were individuated through phase diagrams construction, using the non-ionic surfactant Solutol HS15, being this surfactant acceptable for parenteral administration in human. A selected microemulsion samples containing 0.2 wt% of Delta(9)-THC, stable up to 52 degrees C, was successfully assayed on animal models of pain. Significant antinociceptive activity has been detected by both intraperitoneal and intragastric administration of the new Delta(9)-THC pharmaceutical preparation. The effect has been highlighted in shorter time if compared to a preparation of the same active principle based on previously reported conventional preparation. PMID:20399844

  3. California's BAY-DELTA: USGS Science Supports Decision Making

    USGS Publications Warehouse

    Nickles, James; Taylor, Kimberly; Fujii, Roger

    2010-01-01

    U.S. Geological Survey (USGS) scientists are in the forefront of the effort to understand what causes changes in the hydrology, the ecology and the water quality of the Sacramento-San Joaquin River Delta and the San Francisco Bay estuary. Their scientific findings play a crucial role in how agencies manage the Bay-Delta on a daily basis.

  4. Delta-Isobar magnetic form factor in QCD

    SciTech Connect

    Belyaev, Vladimir

    1993-01-01

    We consider the QCD sum rules approach for Delta-isobar magnetic form factor in the infra-red region $0Delta-isobar magnetic moment.

  5. Exploration gaps exist in Nigeria`s prolific delta

    SciTech Connect

    Thomas, D.

    1995-10-30

    The Niger delta region of the Republic of Nigeria is Africa`s largest oil producing area. It is clear that Nigeria will continue to contribute significantly to world petroleum production well into the 21st century: with increases in recoverable oil reserves in the Niger delta onshore and offshore; the promising potential of the Niger delta deepwater region; and a lesser but not insignificant contribution from the unexplored onshore Benue trough, part of the mid-African rift system, which has already proved to hold substantial oil reserves in the Doba basin of neighboring Chad. This is the first of five parts on Nigeria`s oil and gas potential. The later articles deal with Niger delta oil reserves and production, Niger delta gas reserves, the delta`s deepwater region, and the Benue trough and onshore cretaceous rift basins. This article deals with the geologic setting of the Niger delta-Benue trough region, the synrift deposits, marine sedimentation, margin evolution, geologic strata and reservoirs, reservoir character, structure and traps, hydrocarbon types, geotemperatures, and source rock quality.

  6. Deborah Partridge Wolfe: Biography of a Kappa Delta Pi Laureate

    ERIC Educational Resources Information Center

    van Hover, Stephanie

    2005-01-01

    In 1988, Kappa Delta Pi selected Dr. Deborah Partridge Wolfe for membership in its Laureate Chapter. Wolfe, a prominent African-American social educator, dedicated her career in education to living and promoting the key ideals of Kappa Delta Pi's mission: scholarship, excellence, diversity, inquiry, reflection, and fellowship. This biography of…

  7. Delta: the first pion nucleon resonance - its discovery and applications

    SciTech Connect

    Nagle, D.E.

    1984-07-01

    It is attempted to recapture some of the fun and excitement of the pion-scattering work that led to the discovery of what is now called the delta particle. How significant this discovery was became apparent only gradually. That the delta is alive today and thriving at Los Alamos (as well as other places) is described.

  8. Apple delta 13 discrimination is related to shoot ash content

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant ash content has been highly correlated with plant water use efficiency (WUE), and delta 13 in field crops and grassland species, and proposed as selection criteria for WUE. Delta 18 has also been correlated with transpiration in herbaceous plants. The objectives of the study were to 1) evalu...

  9. Assessments of Water Quality in Mississippi Delta Lake Watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper summarizes watershed scale research by USDA-ARS National Sedimentation Laboratory scientists on the effects of conservation management on water quality and ecology in oxbow lakes of the Mississippi Delta Region, USA. The Mississippi Delta Region is located in the central portion of the U...

  10. 76 FR 28211 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  11. 76 FR 17105 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  12. 76 FR 12017 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  13. 75 FR 67079 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  14. 78 FR 48647 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  15. 76 FR 23970 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  16. 77 FR 53841 - Delta-Bienville Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Delta-Bienville Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Delta-Bienville Resource Advisory Committee will meet in Forest,...

  17. The evolution of a subaqueous delta in the Anthropocene: A stratigraphic investigation of the Brazos River delta, TX USA

    NASA Astrophysics Data System (ADS)

    Carlin, Joseph A.; Dellapenna, Timothy M.

    2015-12-01

    Globally, deltas are increasingly threatened by anthropogenic activities. As a result, deltas now evolve through the combined effects of natural and human-induced processes occurring throughout the fluvial-deltaic system. The Brazos River delta, located along the Texas coast in the northwestern Gulf of Mexico, and its watershed have been impacted by direct and indirect human activities since the late 19th century. This provides an opportunity to investigate how such alterations have shaped the evolution of a delta in the Anthropocene, a time when humans are drivers of geological change. Historic alteration to the delta and watershed include extensive agricultural activity, jetty construction at the mouth in the late 1890s, mouth diversion ~10 km to the southwest in 1929, and reservoir construction throughout the early and mid 20th Century. Three subaerial deltaic geometries provided the framework to connect subaerial deltaic responses, to the anthropogenic alterations, to the resulting stratigraphic characteristics observed in the subaqueous delta. This study utilized high-resolution geophysical data (swath bathymetry, side scan sonar, CHIRP subbottom profiling) on the subaqueous delta to investigate the subaqueous delta stratigraphy and infer the processes that shaped the deltaic record over time. The results showed distinct areas across the subaqueous delta that were dominated by erosion and deposition. Erosional areas corresponded to earlier growth phase depocenters being exposed at the surface, while the depositional areas corresponded to areas with the most recent growth phase depocenter overlying the earlier depocenters. These results highlight that the subaqueous depocenter has migrated westward over time, consistent with the observed changes to the subaerial delta. Additionally, the data showed that evidence for these past growth phases and depocenters may be preserved within the subaqueous delta, even after subaerial portions of the delta returned to pre

  18. Hydrologic Modeling of a Tropical River Delta by Applying Remote Sensing Data: the Niger Delta and its Distributaries.

    NASA Astrophysics Data System (ADS)

    Hannon, M. T.; Syvitski, J. P.; Kettner, A. J.

    2008-12-01

    Delta regions offer rich resources to coastal human populations with their large upstream freshwater sources. Tropical deltas such as the Niger, Nigeria, whose drainage basin incorporates arid regions, receive a significant portion of their runoff from precipitation falling directly on the delta. Between 1970 and 2006, the Niger discharged (Lokoja station) 5000 ± 890 m3/s into upper delta. Here we apply Tropical Rainfall Measurement Mission (TRMM) based precipitation estimates (SB42), with a 0.25° x 0.25° spatial resolution (~100 grid points across the Niger Delta at 3 hourly intervals 1998-2008), and MODIS evapotranspiration (ET) estimates (MOD16), to determine the impact of massive local precipitation events on the routing of water and sediment flux through the Niger Delta's distributaries. The Niger delta receives 2275 mm/y ± 264 mm/y of rainfall with the SE area exceeding 3500 mm/y. The delta's ET varies seasonally between 45 and 65 mm/mo. The in situ generated hydrological runoff is 1675 mm/y, or an equivalent of a discharge 73% the size of the river flux entering the delta. With maximum annual daily discharge from the Niger often exceeding 15,000 m3/s, in combination with the significant in situ runoff, much of the delta's surface is seasonally under floodwaters. LandSat7 imagery indicates delta distributaries that are disconnected from the Niger River, and only drain local precipitation events. This disconnection plays into the discharge and sediment fluxes of these distributaries.

  19. The RCA-F/Delta launch

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Delta 3924 launch vehicle configuration which incorporates the extended long tank Thor booster, nine Castor 4 strap-on motors, the AJ-118 second stage and the TE 364-4 third stage is to place into a synchronous transfer orbit, the second in a series of high-traffic capacity, 24 transponder communications satellites. Three days after launch, the satellite's apogee kick motor circularizes the orbit at geosynchronous altitude of 19,300 NM above the equator at approximately 128 degrees W longitude. The satellite can service commercial and government voice, digital and video communications requirements between Alaska and CONUS. The communications payload, mission requirements and spacecraft systems and subsystems are described.

  20. Method for dissolving delta-phase plutonium

    DOEpatents

    Karraker, David G.

    1992-01-01

    A process for dissolving plutonium, and in particular, delta-phase plutonium. The process includes heating a mixture of nitric acid, hydroxylammonium nitrate (HAN) and potassium fluoride to a temperature between 40.degree. and 70.degree. C., then immersing the metal in the mixture. Preferably, the nitric acid has a concentration of not more than 2M, the HAN approximately 0.66M, and the potassium fluoride 0.1M. Additionally, a small amount of sulfamic acid, such as 0.1M can be added to assure stability of the HAN in the presence of nitric acid. The oxide layer that forms on plutonium metal may be removed with a non-oxidizing acid as a pre-treatment step.

  1. Future capabilities of the Delta launch vehicle

    NASA Technical Reports Server (NTRS)

    Grimes, D. W.; Kraft, J. D.

    1982-01-01

    Design features and payload delivery capabilities of the Delta 3920 launch vehicle are presented. The 3920 is the 14th iteration in a series that was first launched in 1960 and has in recent years surpassed a 97 percent success rate. Capacity is 2800 lb to GEO. The second stage has a propellant capacity of 13,244 lb and a specific impulse of 319.2 sec and produces 9443 lb thrust. The first mission is the Landsat-D satellite and 27 more launches are scheduled through 1985, some associated with different upper stage configurations. The 3924 configuration delivers payload to GEO at a cost of $7500/lb. A fairing has been designed to provide back-up for Shuttle payloads, although the larger size reduces the GEO payload to 2715 lb. Performance enhancements may, however, be gained through pneumatic thrusters for the Castor IV engine separation, higher Castor IV thrust levels, increased booster thrust, and a cryogenic second stage.

  2. Delta method, an empirical drag buildup technique

    NASA Technical Reports Server (NTRS)

    Feagin, R. C.; Morrison, W. D.

    1978-01-01

    An empirical drag correlation technique was developed from analysis of 19 subsonic and supersonic military aircraft and 15 advanced or supercritical airfoil configurations which can be applied in conceptual and advanced aircraft design activities. The Delta Method may be used for estimating the clean wing drag polar for cruise and maneuver conditions up to buffet onset, and to approximately Mach 2.0. This technique incorporates a unique capability of predicting the off-design performance of advanced or supercritical airfoil sections. The buffet onset limit may also be estimated. The method is applicable to wind tunnel models as well as to full scale configurations. This technique has been converted into a computer code for use on the IBM 360 and CDC 7600 computer facilities at NASA AMES. Results obtained using this method to predict known aircraft characteristics are good and agreement can be obtained within a degree of accuracy judged to be sufficient for the initial processes of preliminary design.

  3. Quantitative metrics that describe river deltas and their channel networks

    NASA Astrophysics Data System (ADS)

    Edmonds, Douglas A.; Paola, Chris; Hoyal, David C. J. D.; Sheets, Ben A.

    2011-12-01

    Densely populated river deltas are losing land at an alarming rate and to successfully restore these environments we must understand the details of their morphology. Toward this end we present a set of five metrics that describe delta morphology: (1) the fractal dimension, (2) the distribution of island sizes, (3) the nearest-edge distance, (4) a synthetic distribution of sediment fluxes at the shoreline, and (5) the nourishment area. The nearest-edge distance is the shortest distance to channelized or unchannelized water from a given location on the delta and is analogous to the inverse of drainage density in tributary networks. The nourishment area is the downstream delta area supplied by the sediment coming through a given channel cross section and is analogous to catchment area in tributary networks. As a first step, we apply these metrics to four relatively simple, fluvially dominated delta networks. For all these deltas, the average nearest-edge distances are remarkably constant moving down delta suggesting that the network organizes itself to maintain a consistent distance to the nearest channel. Nourishment area distributions can be predicted from a river mouth bar model of delta growth, and also scale with the width of the channel and with the length of the longest channel, analogous to Hack's law for drainage basins. The four delta channel networks are fractal, but power laws and scale invariance appear to be less pervasive than in tributary networks. Thus, deltas may occupy an advantageous middle ground between complete similarity and complete dissimilarity, where morphologic differences indicate different behavior.

  4. Multimode delta-E effect magnetic field sensors with adapted electrodes

    NASA Astrophysics Data System (ADS)

    Zabel, Sebastian; Reermann, Jens; Fichtner, Simon; Kirchhof, Christine; Quandt, Eckhard; Wagner, Bernhard; Schmidt, Gerhard; Faupel, Franz

    2016-05-01

    We present an analytical and experimental study on low-noise piezoelectric thin film resonators that utilize the delta-E effect of a magnetostrictive layer to measure magnetic fields at low frequencies. Calculations from a physical model of the electromechanical resonator enable electrode designs to efficiently operate in the first and second transversal bending modes. As predicted by our calculations, the adapted electrode design improves the sensitivity by a factor of 6 and reduces the dynamic range of the sensor output by 16 dB, which significantly eases the requirements on readout electronics. Magnetic measurements show a bandwidth of 100 Hz at a noise level of about 100 pTHz-0.5.

  5. Radioactive mineral springs in Delta County, Colorado

    USGS Publications Warehouse

    Cadigan, Robert A.; Rosholt, John N.; Felmlee, J. Karen

    1976-01-01

    The system of springs in Delta County, Colo., contains geochemical clues to the nature and location of buried uranium-mineralized rock. The springs, which occur along the Gunnison River and a principal tributary between Delta and Paonia, are regarded as evidence of a still-functioning hydrothermal system. Associated with the springs are hydrogen sulfide and sulfur dioxide gas seeps, carbon dioxide gas-powered geysers, thick travertine deposits including radioactive travertine, and a flowing warm-water (41?C) radioactive well. Geochemical study of the springs is based on surface observations, on-site water-property measurements, and sampling of water, travertine, soft precipitates, and mud. The spring deposits are mostly carbonates, sulfates, sulfides, and chlorides that locally contain notable amounts of some elements, such as arsenic, barium, lithium, and radium. Samples from five localities have somewhat different trace element assemblages even though they are related to the same hydrothermal system. All the spring waters but one are dominated by sodium chloride or sodium bicarbonate. The exception is an acid sulfate water with a pH of 2.9, which contains high concentrations of aluminum and iron. Most of the detectable radioactivity is due to the presence of radium-226, a uranium daughter product, but at least one spring precipitate contains abundant radium-228, a thorium daughter product. The 5:1 ratio of radium-228 to radium-226 suggests the proximity of a vein-type deposit as a source for the radium. The proposed locus of a thorium-uranium mineral deposit is believed to lie in the vicinity of Paonia, Colo. Exact direction and depth are not determinable from data now available.

  6. 78 FR 22911 - Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Seatac, WA; Delta Air...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-17

    ... Notice of determination was published in the Federal Register on February 8, 2013 (78 FR 8591). Based on... Employment and Training Administration Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Seatac, WA; Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Sioux City,...

  7. Computer-Assisted Instruction in the N.W.T.

    ERIC Educational Resources Information Center

    Garraway, Tom

    For the past seven years, the Division of Educational Research Services at the University of Alberta has been operating an IBM 1500 CAI system. This paper describes demonstration projects set up in anticipation of the establishment of remote CAI in the North West Territories. These include a moon landing simulation program; a diagnostic program in…

  8. Identification and quantitation of 11-nor-delta9-tetrahydrocannabivarin-9-carboxylic acid, a major metabolite of delta9-tetrahydrocannabivarin.

    PubMed

    ElSohly, M A; Feng, S; Murphy, T P; Warrington, A W; Ross, S; Nimrod, A; Mehmedic, Z; Fortner, N

    2001-09-01

    After incubation of delta9-tetrahydrocannabivarin with human hepatocytes, a major metabolic product was detected by gas chromatography-mass spectrometry that showed identical retention time and mass spectrum to the synthetic 11-nor-delta9-tetrahydrocannabivarin-9-carboxylic acid (11-nor-delta9-THCV-9-COOH). Analysis of human urine specimens from marijuana users and plasma samples from Marinol users showed that 11-nor-delta9-THCV-9-COOH was only present in urine specimens of marijuana users. These results supported the conclusion that identification of 11-nor-delta9-THCV-9-COOH in a donor's urine specimen indicates the use or ingestion of cannabis-related product(s) and would not explain the sole use of Marinol. PMID:11550824

  9. Potential exposure of larval and juvenile delta smelt to dissolved pesticides in the Sacramento-San Joaquin Delta, California

    USGS Publications Warehouse

    Kuivila, K.M.; Moon, G.E.

    2004-01-01

    The San Francisco Estuary is critical habitat for delta smelt Hypomesus transpacificus, a fish whose abundance has declined greatly since 1983 and is now listed as threatened. In addition, the estuary receives drainage from the Central Valley, an urban and agricultural region with intense and diverse pesticide usage. One possible factor of the delta smelt population decline is pesticide toxicity during vulnerable larval and juvenile stages, but pesticide concentrations are not well characterized in delta smelt spawning and nursery habitat. The objective of this study was to estimate the potential exposure of delta smelt during their early life stages to dissolved pesticides. For 3 years (1998-2000), water samples from the Sacramento-San Joaquin Delta were collected during April-June in coordination with the California Department of Fish and Game's delta smelt early life stage monitoring program. Samples were analyzed for pesticides using solid-phase extraction and gas chromatography/mass spectrometry. Water samples contained multiple pesticides, ranging from 2 to 14 pesticides in each sample. In both 1999 and 2000, elevated concentrations of pesticides overlapped in time and space with peak densities of larval and juvenile delta smelt. In contrast, high spring outflows in 1998 transported delta smelt away from the pesticide sampling sites so that exposure could not be estimated. During 2 years, larval and juvenile delta smelt were potentially exposed to a complex mixture of pesticides for a minimum of 2-3 weeks. Although the measured concentrations were well below short-term (96-h) LC50 values for individual pesticides, the combination of multiple pesticides and lengthy exposure duration could potentially have lethal or sublethal effects on delta smelt, especially during early larval development.

  10. Flow patterns and morphology of a prograding river delta

    NASA Astrophysics Data System (ADS)

    Shaw, John B.; Mohrig, David; Wagner, R. Wayne

    2016-02-01

    The transition of flow between laterally confined channels and the unchannelized delta front controls the morphodynamic evolution of river deltas but has rarely been measured at the field scale. We quantify flow patterns and bathymetry that define the evolution of the subaqueous delta front on the Wax Lake Delta, a rapidly prograding delta in coastal Louisiana. A significant portion of flow (˜59%) departs the channel network over lateral channel margins as opposed to the downstream channel tips. Bathymetric surveys and remotely sensed estimates of flow direction allow spatial changes in flow velocity to be quantified and patterns of erosion and deposition to be estimated. Shallowing along channel margins produces spatial acceleration and erosion. Lateral spreading, deceleration, and deposition occur within three to eight channel widths outside of the channel margins. In interdistributary bays, the shape of each flow path is constrained by "nourishment boundaries" that separate the outflows from neighboring channels. Deposit elevation decreases with a basinward slope of 2.4 × 10-4 with distance from a channel margin along any flow path, regardless of the channel or location that flow departed the network. Bathymetric depressions called "interdistributary troughs" form along nourishment boundaries where flow paths are the longest and deposit elevation is correspondingly low. We conclude that the deposit morphology exerts a strong control on bathymetric evolution and that interaction between neighboring channels and even neighboring deltas can influence delta front morphology.

  11. Alkaloid delta agonist BW373U86 increases hypoxic tolerance.

    PubMed

    Bofetiado, D M; Mayfield, K P; D'Alecy, L G

    1996-06-01

    Activation of delta opioid receptors increases survival time during acute, lethal hypoxia in mice. delta Agonists therefore present a promising avenue for therapeutic application to reduce the morbidity and mortality associated with clinical hypoxia in settings such as drowning, head injury apnea, and complicated childbirths. However, most delta agonists now available are peptides, and may have limited clinical utility. In the present study, we evaluate the neuroprotective ability of an alkaloid delta agonist, BW373U86. Alkaloid compounds, due to increased stability and increased systemic distribution, may be more favorable for clinical use. We found that BW373U86, like the peptide delta agonist, DPDPE ([D-Pen2, D-Pen5]-enkephalin), increases survival time of mice during lethal hypoxia. The mechanism of neuroprotection induced by delta receptor activation appears to involve decreasing body temperature. Further, using selective opioid receptor antagonists, it appears that BW373U86 exerts these neuroprotective effects by acting at delta-opioid receptors. PMID:8638797

  12. The Mississippi Delta Region: Past, Present, and Future

    NASA Astrophysics Data System (ADS)

    Blum, Michael D.; Roberts, Harry H.

    2012-05-01

    The Mississippi delta region of south Louisiana houses a wealth of resources within a dynamic, subsiding landscape. Foundations for the delta region reflect Neogene evolution of the depocenter, whereas details of the modern landscape reflect late Pleistocene to Holocene evolution of the alluvial-deltaic plain. The Holocene delta plain was constructed by cyclical growth of deltaic headlands, followed by avulsion and relocation of the fluvial sediment source. Abandoned headlands were then submerged and reworked while a new headland was created at the site of active fluvial sediment input. Historic-period levees have decoupled the delta plain from its fluvial sediment source at the same time global sea-level rise was accelerating, which has accelerated delta-plain submergence. Diversions of Mississippi River water and sediment are necessary to achieve delta plain sustainability, but upstream dams trap ˜50% of the total sediment load, and there is not enough supply to keep pace with subsidence and accelerated sea-level rise. The future delta region will not resemble the recent past, and significant drowning is inevitable.

  13. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A booster is lifted for installation onto the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  14. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A booster is raised off a truck bed and prepared for lifting to the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  15. Human gamma delta T-cell recognition of Yersinia enterocolitica.

    PubMed Central

    Young, J L; Goodall, J C; Beacock-Sharp, H; Gaston, J S

    1997-01-01

    We have studied the human gamma delta T-cell response to Yersinia enterocolitica, a facultative intracellular bacterium which causes gastroenteritis and, particularly in human leucocyte antigen (HLA)-B27+ individuals, reactive arthritis (ReA). A marked proliferation of that cytotoxic gamma delta T cells is seen when Yersinia-infected lymphoblastoid cell lines or fixed intact Yersinia are added to cultures of mononuclear cells derived from the synovial fluid of ReA patients or from the peripheral blood of healthy donors. In contrast, heat-inactivated Yersinia fail to stimulate the gamma delta T-cell response. The gamma delta T-cell lines generated killed both autologous and allogeneic infected cell lines. Interestingly, a T-cell line generated from synovial fluid mononuclear cells (SFMC) killed infected autologous cell lines and a cell line matched for HLA-B27 less well than infected allogeneic target cells. gamma delta T-cell clones isolated from this line were found to express V gamma 9V delta 2 T-cell receptor (TCR) and also killed infected mismatched cells more efficiently than autologous targets. Moreover, from experiments using major histocompatability complex (MHC)-deficient cell lines, it was apparent that target cell recognition was MHC independent. Our results suggest that gamma delta T cells can be involved in immunity to Yersinia enterocolitica and should be taken into account when considering immunopathological mechanisms leading to reactive arthritis. PMID:9378487

  16. Delta II rocket prepared for launch of Deep Space 1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A booster is lifted off a truck for installation onto the Boeing Delta 7326 rocket that will launch Deep Space 1 at Launch Pad 17A, Cape Canaveral Air Station. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches. The Delta 7236 has three solid rocket boosters and a Star 37 upper stage. Delta IIs are manufactured in Huntington Beach, Calif. Rocketdyne, a division of The Boeing Company, builds Delta II's main engine in Canoga Park, Calif. Deep Space 1, the first flight in NASA's New Millennium Program, is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999.

  17. Dual antigenic recognition by cloned human gamma delta T cells.

    PubMed Central

    Holoshitz, J; Vila, L M; Keroack, B J; McKinley, D R; Bayne, N K

    1992-01-01

    The function of gamma delta T cells is still elusive. The nature of the antigens that they recognize and the mode of presentation of these antigens are largely unknown. The majority of human peripheral gamma delta T cells bear a V gamma 9/V delta 2 T cell receptor, and display nonclonal reactivity to mycobacteria, without restriction by MHC. It is unknown whether these cells have clonal antigenic specificity as well. Here we describe rheumatoid arthritis-derived V gamma 9/V delta 2 T cell clones, displaying dual antigenic recognition: a nonclonal, MHC-unrestricted recognition of mycobacteria, and a clonal recognition of a short tetanus toxin peptide presented by HLA-DRw53, a nonpolymorphic class II MHC molecule associated with susceptibility to rheumatoid arthritis. This is the first evidence that V gamma 9/V delta 2 T cells can recognize nominal antigenic peptides presented by class II MHC molecules. These results suggest that much like alpha beta T cells, V gamma 9/V delta 2 cells may contribute to the immune response against foreign antigens in an antigen-specific and MHC-restricted manner. The reactivity of these gamma delta T cells to mycobacteria may represent a superantigen-like phenomenon. PMID:1345917

  18. Ancient deltas on Mars: outstanding targets for martian habitability?

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Fawdon, P.; Grindrod, P. M.; Balme, M. R.; Hauber, E.; Warner, N. H.; Muller, J. P.

    2014-12-01

    The identification of putative ancient deltaic sedimentary systems on Mars has been both exciting and controversial. Our excitement is elicted by the potential provided by deltas as evidence for standing bodies of water associated with the deltas, and the resulting implications for both the ancient climate of Mars and ancient habitability. The controversy stems from how confident can we be in the identification of ancient deltaic systems from orbital data, and how robust are our assertions about the habitability potential of such settings. Delta systems in particular are key astrobiological targets because at their distal toes fine-grained sediment (ie., clays) settle from suspension in a lower energy setting and they are commonly characterised by high rates of sedimentation. This leads to high preservation potential of biosignatures. Targeting of future Mars rovers to investigate deltaic landing sites requires better understanding of these issues to reduce exploration risk. In this presentation, we describe the key criteria that enable us to make robust interpretations of deltaic stratigraphy and constrain delta evolution for martian systems. In particular, the past 10 years has seen in a revolution in our process understanding of terrestrial delta systems through a combination of field, experimental and numerical modelling studies. Analysis of martian deltas has much to gain from these results. We go on to consider why deltaic systems offer potential as astrobiological target paleoenvironments. We use the exhumed delta system (Hypanis delta system) at the termination of Hypanis Vallis, 11.8°N, 314.96°E as a case example. This system, situated in Xanthe Terra, comprises layered sedimentary rocks with an overall multi-lobate geometry and associated inverted channel networks. The Hypanis 'delta' is a proposed landing site for the ExoMars rover and also for the NASA 2020 mission.

  19. Verification of Software Product Lines with Delta-Oriented Slicing

    NASA Astrophysics Data System (ADS)

    Bruns, Daniel; Klebanov, Vladimir; Schaefer, Ina

    Software product line (SPL) engineering is a well-known approach to develop industry-size adaptable software systems. SPL are often used in domains where high-quality software is desirable; the overwhelming product diversity, however, remains a challenge for assuring correctness. In this paper, we present delta-oriented slicing, an approach to reduce the deductive verification effort across an SPL where individual products are Java programs and their relations are described by deltas. On the specification side, we extend the delta language to deal with formal specifications. On the verification side, we combine proof slicing and similarity-guided proof reuse to ease the verification process.

  20. Late quaternary evolution of the Orinoco Delta, Venezuela

    USGS Publications Warehouse

    Warne, A.G.; Guevara, E.H.; Aslan, A.

    2002-01-01

    The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel from incising as deeply as many other major river systems. Shallow seismic data indicate that the late Pleistocene Orinoco incised into the present continental shelf, where it formed a braided-river complex that transported sediment to a series of shelf-edge deltas. As sea level rose from 16,000 to 9,500 yrs BP, the Orinoco shoreline shifted rapidly landward, causing shallow-marine waves and currents to form a widespread transgressive sand unit. Decelerating sea-level rise and a warmer, wetter climate during the early Holocene (9,500 to 6,000 yrs BP) induced delta development within the relatively quiet-water environment of the EVB embayment. Sea level approached its present stand in the middle Holocene (6,000 to 3,000 yrs BP), and the Orinoco coast prograded, broadening the delta plain and infilling the EVB embayment. Significant quantities of Amazon sediment began to be transported to the Orinoco coast by littoral currents. Continued progradation in the late Holocene caused the constriction at Boca de Serpientes to alter nearshore and shelf hydrodynamics and subdivide the submarine delta into two distinct areas: the Atlantic shelf and the Gulf of Paria. The increased influence of littoral currents along the coast promoted mudcape development. Because most of the water and sediment were transported across the delta plain through the Rio Grande distributary in the southern delta, much of the central and northwestern delta plain became sediment starved, promoting widespread accumulation of peat deposits. Human impacts on the delta are mostly associated with the Volca??n Dam on Can??o Manamo. However, human activities have had relatively little effect on the

  1. Holocene evolution of the western Orinoco Delta, Venezuela

    USGS Publications Warehouse

    Aslan, A.; White, W.A.; Warne, A.G.; Guevara, E.H.

    2003-01-01

    The pristine nature of the Orinoco Delta of eastern Venezuela provides unique opportunities to study the geologic processes and environments of a major tropical delta. Remote-sensing images, shallow cores, and radiocarbon-dating of organic remains form the basis for describing deltaic environments and interpreting the Holocene history of the delta. The Orinoco Delta can be subdivided into two major sectors. The southeast sector is dominated by the Rio Grande-the principal distributary-and complex networks of anastomosing fluvial and tidal channels. The abundance of siliciclastic deposits suggests that fluvial processes such as over-bank flooding strongly influence this part of the delta. In contrast, the northwest sector is represented by few major distributaries, and overbank sedimentation is less widespread relative to the southeast sector. Peat is abundant and occurs in herbaceous and forested swamps that are individually up to 200 km2 in area. Northwest-directed littoral currents transport large volumes of suspended sediment and produce prominent mudcapes along the northwest coast. Mapping of surface sediments, vegetation, and major landforms identified four principal geomorphic systems within the western delta plain: (1) distributary channels, (2) interdistributary flood basins, (3) fluvial-marine transitional environments, and (4) marine-influenced coastal environments. Coring and radiocarbon dating of deltaic deposits show that the northern delta shoreline has prograded 20-30 km during the late Holocene sea-level highstand. Progradation has been accomplished by a combination of distributary avulsion and mudcape progradation. This style of deltaic progradation differs markedly from other deltas such as the Mississippi where distributary avulsion leads to coastal land loss, rather than shoreline progradation. The key difference is that the Orinoco Delta coastal zone receives prodigious amounts of sediment from northwest-moving littoral currents that transport

  2. Including the {delta}(1232) resonance in baryon chiral perturbation theory

    SciTech Connect

    Hacker, C.; Wies, N.; Scherer, S.; Gegelia, J.

    2005-11-01

    Baryon chiral perturbation theory with explicit {delta}(1232) degrees of freedom is considered. The most general interactions of pions, nucleons, and {delta} consistent with all underlying symmetries as well as with the constraint structure of higher-spin fields are constructed. By use of the extended on-mass-shell renormalization scheme, a manifestly Lorentz-invariant effective-field theory with a systematic power counting is obtained. As applications, we discuss the mass of the nucleon, the pion-nucleon {sigma} term, and the pole of the {delta} propagator.

  3. Delta to alpha prime transformation of plutonium during microhardness testing

    SciTech Connect

    Pereyra, Ramiro A.

    2008-11-15

    Metallic plutonium is a complex material that can exist in six allotropic phases at ambient pressures; and under stress, it can transform martensitically from the ductile face centered cubic delta phase to the brittle monoclinic alpha prime phase. This investigation found that the pressures generated during microhardness indentation are sufficient for the transformation to occur. Micrographs showing the transformation as well as pressure calculations are presented in support for this finding. Also, based upon the amount of material displaced by the indenter, it was determined that there is at least a 16% error in published hardness values of the delta phase that can be attributed to the delta to alpha prime transformation.

  4. Altamaha River Delta, Georgia Sea Islands

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The history of sea islands in the Altamaha River delta on the coast of Georgia is revealed in this image produced from data acquired by the Airborne Synthetic Aperture Radar (AIRSAR), developed and operated by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The outlines of long-lost plantation rice fields, canals, dikes and other inlets are clearly defined. Salt marshes are shown in red, while dense cypress and live oak tree canopies are seen in yellow-greens.

    Agricultural development of the Altamaha delta began soon after the founding of the Georgia Colony in 1733. About 25 plantations were located on the low-lying islands and shores by the 19th century, taking advantage of the rich alluvial flow and annual inundation of water required by some crops. The first major crop was indigo; when demand for that faded, rice and cotton took its place. A major storm in 1824 destroyed much of the town of Darien (upper right) and put many of the islands under 20 feet of water. The Civil War ended the plantation system, and many of the island plantations disappeared under heavy brush and new growth pine forests. Some were used as tree farms for paper and pulp industries, while the Butler Island (center left) plantation became a wildlife conservation site growing wild sea rice for migrating ducks and other waterfowl. Margaret Mitchell is reputed to have used the former owner of the Butler Plantation as a basis for the Rhett Butler character in her novel 'Gone With The Wind,' taking the first name from Rhett's Island (lower right).

    These data were obtained during a 1994-95 campaign along the Georgia coast. AIRSAR's ability to detect vegetation canopy density, hydrological features and other topographic characteristics is a useful tool in landscape archaeology. AIRSAR flies aboard a NASA DC-8 based at NASA's Dryden Flight Research Center, Edwards, Calif. The analysis on the data shown was accomplished by Dr. Gary Mckay, Department of Archaeology and Geography, and Ian

  5. Volga Delta and the Caspian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Russia's Volga River is the largest river system in Europe, draining over 1.3 million square kilometers of catchment area into the Caspian Sea. The brackish Caspian is Earth's largest landlocked water body, and its isolation from the world's oceans has enabled the preservation of several unique animal and plant species. The Volga provides most of the Caspian's fresh water and nutrients, and also discharges large amounts of sediment and industrial waste into the relatively shallow northern part of the sea. These images of the region were captured by the Multi-angle Imaging SpectroRadiometer on October 5, 2001, during Terra orbit 9567. Each image represents an area of approximately 275 kilometers x 376 kilometers.

    The left-hand image is from MISR's nadir (vertical-viewing) camera, and shows how light is reflected at red, green, and blue wavelengths. The right-hand image is a false color composite of red-band imagery from MISR's 60-degree backward, nadir, and 60-degree forward-viewing cameras, displayed as red, green, and blue, respectively. Here, color variations indicate how light is reflected at different angles of view. Water appears blue in the right-hand image, for example, because sun glitter makes smooth, wet surfaces look brighter at the forward camera's view angle. The rougher-textured vegetated wetlands near the coast exhibit preferential backscattering, and consequently appear reddish. A small cloud near the center of the delta separates into red, green, and blue components due to geometric parallax associated with its elevation above the surface.

    Other notable features within the images include several linear features located near the Volga Delta shoreline. These long, thin lines are artificially maintained shipping channels, dredged to depths of at least 2 meters. The crescent-shaped Kulaly Island, also known as Seal Island, is visible near the right-hand edge of the images.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory

  6. The primary structure of Plasmodium falciparum DNA polymerase delta is similar to drug sensitive delta-like viral DNA polymerases.

    PubMed

    Fox, B A; Bzik, D J

    1991-12-01

    We report the isolation and sequencing of genomic DNA clones that encode the 1094-amino acid catalytic subunit of DNA polymerase delta from the human malaria parasite Plasmodium falciparum. Protein sequence comparison to other DNA polymerases revealed the presence of six highly conserved regions found in alpha-like DNA polymerases from different prokaryotic, viral, and eukaryotic sources. Five additional regions of amino acid sequence similarity that are only conserved in delta and delta-like DNA polymerases, so far, were present in P. falciparum DNA polymerase delta. P. falciparum DNA polymerase delta was highly similar to both Saccharomyces cerevisiae DNA polymerase delta (DNA polymerase III; CDC2) and Epstein-Barr virus DNA polymerase at the amino acid sequence, and the predicted protein secondary structure levels. The gene that encodes DNA polymerase delta resides as a single copy on chromosome 10, and is expressed as a 4.5-kb mRNA during the trophozoite and schizont stages when parasite chromosomal DNA synthesis is active. PMID:1775172

  7. Birds' tails do act like delta wings but delta-wing theory does not always predict the forces they generate.

    PubMed Central

    Evans, Matthew R

    2003-01-01

    Delta-wing theory, which predicts the aerodynamics of aircraft like the Concorde, is the conventional explanation for the way in which a bird's tail operates in flight. Recently, doubt has been cast on the validity of applying a theory devised for supersonic aircraft to the small tails of slow-flying birds. By testing delta-wing models and birds' tails behind bodies with wings, I empirically show that the tails of birds produce lift in a very similar way to conventional delta-wing models. Both Perspex and birds' tail models produce lift similar to that predicted by delta-wing theory when narrowly spread and at low angles of attack. However, when widely spread and at high angles of attack, both tails and Perspex models produce much less lift than predicted, owing to vortex breakdown after which the assumptions of delta-wing theory are violated. These results indicate that birds' tails can be regarded as delta wings but that the theory predicting the forces produced by delta wings can only be applied within acceptable limits (i.e. tails spread less than 60 degrees and at angles of attack of less than 20 degrees). PMID:12965029

  8. Delta Morphodynamics Matters! Ecosystem Services, Poverty and Morphodynamic Change in the Ganges-Brahmaputra Mega-Delta

    NASA Astrophysics Data System (ADS)

    Nicholls, R. J.; Adger, N.; Allan, A.; Darby, S. E.; Hutton, C.; Matthews, Z.; Rahman, M.; Whitehead, P. G.; Wolf, J.

    2013-12-01

    The world's deltas are probably the most vulnerable type of coastal environment, and they face multiple stresses in the coming decades. These stresses include, amongst others, local drivers due to land subsidence, population growth and urbanisation within the deltas, regional drivers due to changes in catchment management (e.g. upstream land use and dam construction), as well as global climate change impacts such as sea-level rise. At the same time, the ecosystem services of river deltas support high population densities, with around 14% of the global population inhabiting deltas. A large proportion of these people experience extremes of poverty and they are therefore severely exposed to vulnerability from environmental and ecological stress and degradation. In areas close to or below the poverty boundary, both subsistence and cash elements of the economy tend to rely disproportionately heavily on ecosystem services which underpin livelihoods. Therefore, to sustainably manage delta environments they must be viewed as complex social-environmental systems where change is only partially driven by physical drivers such as sea level rise and climate change, and human-induced development activities are also critical. Here we outline a new conceptual framework for the development of methods to understand and characterise the key drivers of change in ecosystem services that affect the environment and economic status of populous deltas, focusing specifically on the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The GBM delta is characterised by densely populated coastal lowlands with significant poverty, with livelihoods supported to a large extent by natural ecosystems such as the Sunderbahns (the largest mangrove forest in the world). However, the GBM delta is under severe development pressure due to many growing cities. At present the importance of ecosystems services to poverty and livelihoods is poorly understood. This is due to due to the complexity of interactions

  9. BSM Delta Qualification 2, volume 2

    NASA Astrophysics Data System (ADS)

    1994-11-01

    This report, presented in three volumes, provides the results of a two-motor Delta Qualification 2 program conducted in 1993 to certify the following enhancements for incorporation into booster separation motor (BSM) flight hardware: vulcanized-in-place nozzle aft closure insulation; new iso-static ATJ bulk graphite throat insert material; adhesive EA 9394 for bonding the nozzle throat, igniter grain rod/centering insert/igniter case; deletion of the igniter adapter insulator ring; deletion of the igniter adapter/igniter case interface RTV; and deletion of loctite from igniter retainer plate threads. The enhancements above directly resulted from (1) the BSM total quality management (TQM) team initiatives to enhance the BSM producibility, and (2) the necessity to qualify new throat insert and adhesive systems to replace existing materials that will not be available. Testing was completed at both the component and motor levels. Component testing was accomplished to screen candidate materials (e.g., throat materials, adhesive systems) and to optimize processes (e.g., aft closure insulator vulcanization approach) prior to their incorporation into the test motors. Motor tests -- consisting of two motors, randomly selected by USBI's on-site quality personnel from production lot AAY, which were modified to accept the enhancements -- were completed to provide the final qualification of the enhancements for incorporation into flight hardware. Volume 2 details the environmental testing (vibration and shock) conducted at Marshall Space Flight Center (MSFC) to which the motors were subjected prior to static tests.

  10. Forests fuel fish growth in freshwater deltas

    PubMed Central

    Tanentzap, Andrew J.; Szkokan-Emilson, Erik J.; Kielstra, Brian W.; Arts, Michael T.; Yan, Norman D.; Gunn, John M.

    2014-01-01

    Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish. PMID:24915965

  11. Delta Haptic Device as a nanomanipulator

    NASA Astrophysics Data System (ADS)

    Grange, Sebastien; Conti, Francois; Helmer, Patrick; Rouiller, Patrice; Baur, Charles

    2001-10-01

    At the EPFL, we have developed a force-feedback device and control architecture for high-end research and industrial applications. The Delta Haptic Device (DHD) consists of a 6 degrees-of-freedom (DOF) mecatronic device driven by a PC. Several experiments have been carried out in the fields of manipulation and simulation to assess the dramatic improvement haptic information brings to manipulation. This system is particularly well suited for scaled manipulation such as micro-, nano- and biomanipulation. Not only can it perform geometric and force scaling, but it can also include fairly complex physical models into the control loop to assist manipulation and enhance human understanding of the environment. To demonstrate this ability, we are currently interfacing our DHD with an atomic force microscope (AFM). In a first stage, we will be able to feel in real-time the topology of a given sample while visualizing it in 3D. The aim of the project is to make manipulation of carbon nanotubes possible by including physical models of such nanotubes behavior into the control loop, thus allowing humans to control complex structures. In this paper, we give a brief description of our device and present preliminary results of its interfacing with the AFM.

  12. Status of the Synchrotron Light Source DELTA

    SciTech Connect

    Berges, U.; Sternemann, C.; Tolan, M.; Westphal, C.; Weis, T.; Wille, K.

    2007-01-19

    The Dortmund Electron Accelerator DELTA, a 1.5 GeV synchrotron light source located at University of Dortmund, is operated for 3000 h per year including 2000 h beam time for synchrotron radiation use and 1000 h for machine physics, optimisation and maintenance. The status of the synchrotron light source is presented with emphasis on the operation, commissioning and installation of beamlines and insertion devices. The soft X-ray undulator beamlines provide photon energies between 5 to 400 eV (U250) and 55 and 1500 eV (U55), respectively. One dipole beamline covers soft X-rays between 6 to 200 eV, and a second dipole beamline is used without a monochromator at 2.2 keV critical energy of the dipole spectrum. For photons in the hard X-ray regime, a superconducting asymmetric wiggler (SAW) with a field of 5.3 T and 7.9 keV critical energy was installed, providing circularly polarized X-rays in the range of 2 to 30 keV. Due to its broad radiation fan, three beamlines are simultaneously served. The first SAW-beamline with an energy range between 4 to 30 keV is in full operation, the second is under commissioning, serving the energy range between 2 to 30 keV. The third SAW beamline is near completion, additional dipole beamlines are under construction.

  13. The ISAS Synchrotron Microprobe at DELTA

    SciTech Connect

    Bohlen, Alex von; Kraemer, Markus; Hergenroeder, Roland; Berges, Ulf

    2007-01-19

    Since 2004 ISAS operates a dipole beamline at the synchrotron radiation facility DELTA at University of Dortmund. Synchrotron radiation is used at this beamline as an excellent excitation source for X-ray fluorescence spectrometry (XRF). Among others, the high brilliance of the synchrotron radiation in contrast to conventional X-ray tubes, the strong polarization of the synchrotron radiation and the low divergence of the electron beam can be applied to XRF offering several advantages for spectroscopy. These outstanding features encouraged us to develop and operate a synchrotron radiation induced X-ray micro fluorescence probe connected to a wavelength dispersive spectrometer (SR-WDXRF). A relevant characteristic of such a device, namely, good lateral resolution at high spectral resolution can be applied for single spot-, line-scan and area map analyses of a variety of objects. The instrumentation of the SR-WDXRF and the performed experiments will be presented. Main task is the detection of light elements by their fluorescence K-lines and the specification of element compounds.

  14. Theoretical studies on flapped delta wings

    NASA Technical Reports Server (NTRS)

    Oh, S.; Tavella, D.; Roberts, L.

    1988-01-01

    The effects of leading edge flaps on the aerodynamic characteristics of a low aspect-ratio delta wing are studied theoretically. As an extension of the classical crossflow plane analysis and in order to include separated shear layers, an analogy between three dimensional steady conical and two dimensional unsteady self-similar flows is explored. This analogy provides a simple steady-unsteady relationship. The criteria for the validity of the steady-unsteady analogy are also examined. Two different theoretical techniques are used to represent the separated shear layers based on the steady-unsteady analogy, neglecting the trailing edge effect. In the first approach, each vortex system is represented by a pair of concentrated vortices connected to the separation points by straight feeding sheets. In the second approach, the vortex cloud method is adopted for simulating the flow field in the crossflow plane. The separated shear layers are replaced with a cloud of discrete vortices and the boundary element method is employed to represent the wing trace by a vorticity distribution. A simple merging scheme is used to model the core region of the vortical flow as a single vortex by imposing a restriction on the shear layer rotation angle. The results are compared with experiments and with results from 3-D panel calculations.

  15. Delta 2 Explosion Plume Analysis Report

    NASA Technical Reports Server (NTRS)

    Evans, Randolph J.

    2000-01-01

    A Delta II rocket exploded seconds after liftoff from Cape Canaveral Air Force Station (CCAFS) on 17 January 1997. The cloud produced by the explosion provided an opportunity to evaluate the models which are used to track potentially toxic dispersing plumes and clouds at CCAFS. The primary goal of this project was to conduct a case study of the dispersing cloud and the models used to predict the dispersion resulting from the explosion. The case study was conducted by comparing mesoscale and dispersion model results with available meteorological and plume observations. This study was funded by KSC under Applied Meteorology Unit (AMU) option hours. The models used in the study are part of the Eastern Range Dispersion Assessment System (ERDAS) and include the Regional Atmospheric Modeling System (RAMS), HYbrid Particle And Concentration Transport (HYPACT), and Rocket Exhaust Effluent Dispersion Model (REEDM). The primary observations used for explosion cloud verification of the study were from the National Weather Service's Weather Surveillance Radar 1988-Doppler (WSR-88D). Radar reflectivity measurements of the resulting cloud provided good estimates of the location and dimensions of the cloud over a four-hour period after the explosion. The results indicated that RAMS and HYPACT models performed reasonably well. Future upgrades to ERDAS are recommended.

  16. BSM Delta qualification 2, volume 1

    NASA Astrophysics Data System (ADS)

    1994-11-01

    This report, presented in three volumes, provides the results of a two-motor Delta Qualification 2 program conducted in 1993 to certify the following enhancements for incorporation into Booster Separation Motor (BSM) flight hardware: (1) vulcanized-in-place nozzle aft closure insulation; (2) new isostatic ATJ bulk graphite throat insert material; (3) adhesive EA 9394 for bonding the nozzle throat, igniter grain rod/centering insert/igniter case; (4) deletion of the igniter adapter insulator ring; (5) deletion of igniter adapter/igniter case interface RTV; and (6) deletion of Loctite from igniter retainer plate threads. The enhancements above directly resulted from (1) the BSM Total Quality Management (TQM) Team initiatives to enhance the BSM producibility, and (2) the necessity to qualify new throat insert and adhesive systems to replace existing materials that will not be available. Testing was completed at both the component and motor levels. Component testing was accomplished to screen candidate materials (e.g., throat materials, adhesive systems) and to optimize processes (e.g., aft closure insulator vulcanization approach) prior to their incorporation into the test motors. Motor testing - consisting of two motors, randomly selected by USBI's onsite quality personnel from production lot AAY, which were modified to accept the enhancements - were completed to provide the final qualification of the enhancements for incorporation into flight hardware. It is concluded that all of the enhancements herein tested are qualified to be incorporated into flight hardware for the BSM.

  17. The hepatitis delta virus: Replication and pathogenesis.

    PubMed

    Sureau, Camille; Negro, Francesco

    2016-04-01

    Hepatitis delta virus (HDV) is a defective virus and a satellite of the hepatitis B virus (HBV). Its RNA genome is unique among animal viruses, but it shares common features with some plant viroids, including a replication mechanism that uses a host RNA polymerase. In infected cells, HDV genome replication and formation of a nucleocapsid-like ribonucleoprotein (RNP) are independent of HBV. But the RNP cannot exit, and therefore propagate, in the absence of HBV, as the latter supplies the propagation mechanism, from coating the HDV RNP with the HBV envelope proteins for cell egress to delivery of the HDV virions to the human hepatocyte target. HDV is therefore an obligate satellite of HBV; it infects humans either concomitantly with HBV or after HBV infection. HDV affects an estimated 15 to 20 million individuals worldwide, and the clinical significance of HDV infection is more severe forms of viral hepatitis--acute or chronic--, and a higher risk of developing cirrhosis and hepatocellular carcinoma in comparison to HBV monoinfection. This review covers molecular aspects of HDV replication cycle, including its interaction with the helper HBV and the pathogenesis of infection in humans. PMID:27084031

  18. Forests fuel fish growth in freshwater deltas.

    PubMed

    Tanentzap, Andrew J; Szkokan-Emilson, Erik J; Kielstra, Brian W; Arts, Michael T; Yan, Norman D; Gunn, John M

    2014-01-01

    Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish. PMID:24915965

  19. BSM Delta qualification 2, volume 1

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This report, presented in three volumes, provides the results of a two-motor Delta Qualification 2 program conducted in 1993 to certify the following enhancements for incorporation into Booster Separation Motor (BSM) flight hardware: (1) vulcanized-in-place nozzle aft closure insulation; (2) new isostatic ATJ bulk graphite throat insert material; (3) adhesive EA 9394 for bonding the nozzle throat, igniter grain rod/centering insert/igniter case; (4) deletion of the igniter adapter insulator ring; (5) deletion of igniter adapter/igniter case interface RTV; and (6) deletion of Loctite from igniter retainer plate threads. The enhancements above directly resulted from (1) the BSM Total Quality Management (TQM) Team initiatives to enhance the BSM producibility, and (2) the necessity to qualify new throat insert and adhesive systems to replace existing materials that will not be available. Testing was completed at both the component and motor levels. Component testing was accomplished to screen candidate materials (e.g., throat materials, adhesive systems) and to optimize processes (e.g., aft closure insulator vulcanization approach) prior to their incorporation into the test motors. Motor testing - consisting of two motors, randomly selected by USBI's onsite quality personnel from production lot AAY, which were modified to accept the enhancements - were completed to provide the final qualification of the enhancements for incorporation into flight hardware. It is concluded that all of the enhancements herein tested are qualified to be incorporated into flight hardware for the BSM.

  20. BSM Delta Qualification 2, volume 2

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This report, presented in three volumes, provides the results of a two-motor Delta Qualification 2 program conducted in 1993 to certify the following enhancements for incorporation into booster separation motor (BSM) flight hardware: vulcanized-in-place nozzle aft closure insulation; new iso-static ATJ bulk graphite throat insert material; adhesive EA 9394 for bonding the nozzle throat, igniter grain rod/centering insert/igniter case; deletion of the igniter adapter insulator ring; deletion of the igniter adapter/igniter case interface RTV; and deletion of loctite from igniter retainer plate threads. The enhancements above directly resulted from (1) the BSM total quality management (TQM) team initiatives to enhance the BSM producibility, and (2) the necessity to qualify new throat insert and adhesive systems to replace existing materials that will not be available. Testing was completed at both the component and motor levels. Component testing was accomplished to screen candidate materials (e.g., throat materials, adhesive systems) and to optimize processes (e.g., aft closure insulator vulcanization approach) prior to their incorporation into the test motors. Motor tests -- consisting of two motors, randomly selected by USBI's on-site quality personnel from production lot AAY, which were modified to accept the enhancements -- were completed to provide the final qualification of the enhancements for incorporation into flight hardware. Volume 2 details the environmental testing (vibration and shock) conducted at Marshall Space Flight Center (MSFC) to which the motors were subjected prior to static tests.

  1. Morphologic and stratigraphic evolution of muddy ebb-tidal deltas along a subsiding coast: Barataria Bay, Mississippi River delta

    USGS Publications Warehouse

    FitzGerald, D.M.; Kulp, M.; Penland, S.; Flocks, J.; Kindinger, J.

    2004-01-01

    The Barataria barrier coast formed between two major distributaries of the Mississippi River delta: the Plaquemines deltaic headland to the east and the Lafourche deltaic headland to the west. Rapid relative sea-level rise (1??03 cm year-1) and other erosional processes within Barataria Bay have led to substantial increases in the area of open water (> 775 km2 since 1956) and the attendant bay tidal prism. Historically, the increase in tidal discharge at inlets has produced larger channel cross-sections and prograding ebb-tidal deltas. For example, the ebb delta at Barataria Pass has built seaward > 2??2 km since the 1880s. Shoreline erosion and an increasing bay tidal prism also facilitated the formation of new inlets. Four major lithofacies characterize the Barataria coast ebb-tidal deltas and associated sedimentary environments. These include a proximal delta facies composed of massive to laminated, fine grey-brown to pale yellow sand and a distal delta facies consisting of thinly laminated, grey to pale yellow sand and silty sand with mud layers. The higher energy proximal delta deposits contain a greater percentage of sand (75-100%) compared with the distal delta sediments (60-80%). Associated sedimentary units include a nearshore facies consisting of horizontally laminated, fine to very fine grey sand with mud layers and an offshore facies that is composed of grey to dark grey, laminated sandy silt to silty clay. All facies coarsen upwards except the offshore facies, which fines upwards. An evolutionary model is presented for the stratigraphic development of the ebb-tidal deltas in a regime of increasing tidal energy resulting from coastal land loss and tidal prism growth. Ebb-tidal delta facies prograde over nearshore sediments, which interfinger with offshore facies. The seaward decrease in tidal current velocity of the ebb discharge produces a gradational contact between proximal and distal tidal delta facies. As the tidal discharge increases and the inlet

  2. The late-Holocene progradation of the Mahakam Delta, Indonesia - A case study of tidal, tropical deltas

    NASA Astrophysics Data System (ADS)

    Dalman, R.; Ranawijaya, D.; Missiaen, T.; Kroonenberg, S.; Storms, J.

    2011-12-01

    The Mahakam Delta is an oft-cited example of a mixed fluvial-tidally influenced delta. Yet the distinct separation of the tide-dominated delta plain and the fluvial distributaries make the delta unique amongst tidally influenced deltas. The delta prograded an average of 60 km over the last 5000 years. Most sediment transport is induced by tidal currents and fluvial discharge, which resulted in a distinct, dense network of distributary and tidal channels. In order to characterize the Holocene sedimentary architecture we describe a dataset of 10 new cores and a large survey of very high-resolution, shallow seismics. The seismics are recorded using an echosounder with a novel parametric source, allowing subsurface penetration in excess of 15 m while achieving a vertical resolution of 0.2 m. Distinct sedimentary facies are described in detail for delta plain, delta front, distributary and mouthbar deposits. A notable difference in stratal pattern has been observed between the inner and outer tide-dominated delta plain facies. The inner tidal channels cut deeply into the underlying deltafront deposits and form a distinct heterogenic laterally accreting and intercutting facies. Whereas the outer tide-dominated delta plain deposits accrete conformably on the marine deltafront facies and show a much more homogenous sedimentary architecture. The continual reworking of the inner tide-dominated delta plain results in a patchwork of deposits greatly varying in thickness and age albeit with a similar silty clay lithology. The area of the present-day delta was largely flooded after the early to mid-Holocene transgression, our data indicate that a small branch of fluvial distributaries was active on the current delta plain around 5 ka. Subsequently, the northernmost fluvial distributary built out rapidly over a period of 3 kyrs. The southern distributaries built out later, from 2 ka to the present. The mouthbar deposits in the south are significantly thicker than in the northern

  3. Profiling risk and sustainability in coastal deltas of the world

    NASA Astrophysics Data System (ADS)

    Tessler, Z. D.; Vörösmarty, C. J.; Grossberg, M.; Gladkova, I.; Aizenman, H.; Syvitski, J. P. M.; Foufoula-Georgiou, E.

    2015-08-01

    Deltas are highly sensitive to increasing risks arising from local human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. We quantified changing flood risk due to extreme events using an integrated set of global environmental, geophysical, and social indicators. Although risks are distributed across all levels of economic development, wealthy countries effectively limit their present-day threat by gross domestic product-enabled infrastructure and coastal defense investments. In an energy-constrained future, such protections will probably prove to be unsustainable, raising relative risks by four to eight times in the Mississippi and Rhine deltas and by one-and-a-half to four times in the Chao Phraya and Yangtze deltas. The current emphasis on short-term solutions for the world’s deltas will greatly constrain options for designing sustainable solutions in the long term.

  4. HD 106426, a new multiperiodic delta Scuti variable

    NASA Astrophysics Data System (ADS)

    Honkova, K.; Jurysek, J.; Masek, M.; Paunzen, E.; Zejda, M.

    2014-06-01

    We present the time series analysis of CCD photometry from FRAM telescope at the Pierre Auger Observatory (PAO, Argentina) for HD 106426. In addition, we analysed the data from ASAS. HD 106426 is a new multiperiodic delta Scuti variable.

  5. On the origin of delta spots. [on sun

    NASA Technical Reports Server (NTRS)

    Tang, F.

    1983-01-01

    Mount Wilson sunspot drawings from 1966 through 1980 were used in conjunction with H-alpha filtergrams from Big Bear Solar Observatory to examine the origin of delta spots, spots with bipolar umbrae within one penumbra. Of the six cases studied, five were formed by the union of non-paired spots. They are either shoved into one another by two neighboring growing bipoles or by a new spot borne piggy-back style on an existing spot of opposite polarity. Proper motions of the growing spots take on curvilinear paths around one another to avoid a collision. This is the shear motion observed in delta spots (Tanaka, 1979). In the remaining case, the delta spot was formed by spots that emerged as a pair. The findings indicate no intrinsic differences in the formation or the behavior between delta spots and spots of normal magnetic configuration.

  6. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, provides many ecosystem services to the people of the area, including food, fuel, transportation, climate regulation, water purificati...

  7. A variable-step-size robust delta modulator.

    NASA Technical Reports Server (NTRS)

    Song, C. L.; Garodnick, J.; Schilling, D. L.

    1971-01-01

    Description of an analytically obtained optimum adaptive delta modulator-demodulator configuration. The device utilizes two past samples to obtain a step size which minimizes the mean square error for a Markov-Gaussian source. The optimum system is compared, using computer simulations, with a linear delta modulator and an enhanced Abate delta modulator. In addition, the performance is compared to the rate distortion bound for a Markov source. It is shown that the optimum delta modulator is neither quantization nor slope-overload limited. The highly nonlinear equations obtained for the optimum transmitter and receiver are approximated by piecewise-linear equations in order to obtain system equations which can be transformed into hardware. The derivation of the experimental system is presented.

  8. Characterization of a delta-electroencephalogram (-sleep)-inducing peptide.

    PubMed

    Schoenenberger, G A; Monnier, M

    1977-03-01

    A peptide that induces slow-wave (delta) and spindles electroencephalogram enhancement after intraventricular (brain) infusion has been isolated from rabbits and given the name delta-sleep-inducing peptide (DSIP). Amino acid seqeunce: Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. This compound, five possible metabolic products (containing residues 1--8, 2--9, 2--8, 1--4, and 5--9), two nonapeptide analogues with two amino acids exchanged, and a related tripeptide (Trp-Ser-Glu) were synthesized. All nine synthetic peptides were infused intraventricularly in rabbits under double-blind conditions. A total of 58 rabbits including controls were evaluated. The electroencephalogram leads from the neocortex and the archicortex were directly fast-Fourier transformed and analyzed by a Univac 1108 computer system. Only the delta-sleep-inducing peptide (snythetic) showed significant and specific enhancement/induction of delta and spindle electroencephalogram patterns. PMID:265572

  9. Establishment report: Reforestation of the Pen Branch corridor and delta

    SciTech Connect

    Nelson, E.A.; Dulohery, N.J.; Bunton, C.S.; Trettin, C.C.; McKee, W.H. Jr.

    1995-12-01

    This report documents the role of the USDA Forest Service in the reforestation of the Pen Branch floodplain and delta. The report focuses upon the reforestation activities and monitoring to characterize the sites.

  10. 31 CFR 1010.655 - Special measures against Banco Delta Asia.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Special measures against Banco Delta... Delta Asia. (a) Definitions. For purposes of this section: (1) Banco Delta Asia means all branches, offices, and subsidiaries of Banco Delta Asia operating in any jurisdiction, including its...

  11. 31 CFR 1010.655 - Special measures against Banco Delta Asia.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Special measures against Banco Delta... Delta Asia. (a) Definitions. For purposes of this section: (1) Banco Delta Asia means all branches, offices, and subsidiaries of Banco Delta Asia operating in any jurisdiction, including its...

  12. 31 CFR 1010.655 - Special measures against Banco Delta Asia.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Special measures against Banco Delta... Delta Asia. (a) Definitions. For purposes of this section: (1) Banco Delta Asia means all branches, offices, and subsidiaries of Banco Delta Asia operating in any jurisdiction, including its...

  13. 76 FR 37643 - Safety Zone; Delta Independence Day Foundation Celebration, Mandeville Island, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-28

    ... SECURITY Coast Guard 33 CFR Part 165 Docket No. USCG-2011-0395] RIN 1625-AA00 Safety Zone; Delta... Delta Independence Day Fireworks Foundation Celebration. This temporary safety zone is established to... Purpose The Delta Independence Day Foundation will sponsor the Delta Independence Day...

  14. 31 CFR 1010.655 - Special measures against Banco Delta Asia.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Special measures against Banco Delta... Delta Asia. (a) Definitions. For purposes of this section: (1) Banco Delta Asia means all branches, offices, and subsidiaries of Banco Delta Asia operating in any jurisdiction, including its...

  15. Earthshots: Satellite images of environmental change – Ayeyarwady Delta, Myanmar

    USGS Publications Warehouse

    Adamson, Thomas

    2013-01-01

    The Ayeyarwady Delta—also called the Irrawaddy Delta—is a vast alluvial floodplain. The delta spans over 35,000 km2 (13,500 mi2) and was once home to an extensive tract of mangrove forests, but deforestation has changed the landscape. One scientific study estimated that the delta lost 1,685 km2 (651 mi2) from 1978 to 2011. This 40-year sequence of Landsat images shows the relatively rapid loss of mangrove forest.

  16. Chiral Effective Field Theory in the $\\Delta$-resonance region

    SciTech Connect

    Vladimir Pascalutsa

    2006-09-18

    I discuss the problem of constructing an effective low-energy theory in the vicinity of a resonance or a bound state. The focus is on the example of the $\\Delta(1232)$, the lightest resonance in the nucleon sector. Recent developments of the chiral effective-field theory in the $\\Delta$-resonance region are briefly reviewed. I conclude with a comment on the merits of the manifestly covariant formulation of chiral EFT in the baryon sector.

  17. Multifunction audio digitizer. [producing direct delta and pulse code modulation

    NASA Technical Reports Server (NTRS)

    Monford, L. G., Jr. (Inventor)

    1974-01-01

    An illustrative embodiment of the invention includes apparatus which simultaneously produces both direct delta modulation and pulse code modulation. An input signal, after amplification, is supplied to a window comparator which supplies a polarity control signal to gate the output of a clock to the appropriate input of a binary up-down counter. The control signals provide direct delta modulation while the up-down counter output provides pulse code modulation.

  18. Parallel (delta + 1) coloring of constant-degree graphs

    SciTech Connect

    Goldberg, A.V.; Plotkin, S.A.

    1986-12-01

    This paper presents parallel algorithms for coloring a constant-degree graph with a maximum degree of delta in (delta + 1) colors and for finding a maximal independent set in a constant-degree graph. Given a graph with n vertices, the algorithms run in O (lg*n) time on EREW PRAM with O(n) processors. The algorithms use only local communication and achieve the same complexity bounds when implemented in the distributed model of parallel computation.

  19. Temperature independent quantum well FET with delta channel doping

    NASA Technical Reports Server (NTRS)

    Young, P. G.; Mena, R. A.; Alterovitz, S. A.; Schacham, S. E.; Haugland, E. J.

    1992-01-01

    A temperature independent device is presented which uses a quantum well structure and delta doping within the channel. The device requires a high delta doping concentration within the channel to achieve a constant Hall mobility and carrier concentration across the temperature range 300-1.4 K. Transistors were RF tested using on-wafer probing and a constant G sub max and F sub max were measured over the temperature range 300-70 K.

  20. Analog Delta-Back-Propagation Neural-Network Circuitry

    NASA Technical Reports Server (NTRS)

    Eberhart, Silvio

    1990-01-01

    Changes in synapse weights due to circuit drifts suppressed. Proposed fully parallel analog version of electronic neural-network processor based on delta-back-propagation algorithm. Processor able to "learn" when provided with suitable combinations of inputs and enforced outputs. Includes programmable resistive memory elements (corresponding to synapses), conductances (synapse weights) adjusted during learning. Buffer amplifiers, summing circuits, and sample-and-hold circuits arranged in layers of electronic neurons in accordance with delta-back-propagation algorithm.

  1. Delta mission planning in the Shuttle transition era

    NASA Technical Reports Server (NTRS)

    Grimes, D. W.

    1982-01-01

    Delta mission planning is aimed at providing Shuttle transition era user support which is flexible, dependable, and reliable. The flexibility of support is being enhanced by the development of a new Delta vehicle model, the 3920, capable of providing backup compatible performance for Shuttle SSUS-D (solid spinning upper stage) users. Reliable interfaces, flexible scheduling policies, and new launch facilities will help satisfy increased user demand.

  2. The Great Diversion: Danube Delta under Human Control (Invited)

    NASA Astrophysics Data System (ADS)

    Giosan, L.

    2009-12-01

    Many deltas around the world are suffering from sediment deficits that render them unstable to current and predicted rates of sea level rise. One solution proposed to alleviate the complete or partial drowning of such deltas is the use of river diversions to increase the quantity of sediment supplied to the delta plain to support marsh accretion. We examine the results of a half century old program of diversion in the Danube delta that led to the creation of an extensive diversion channel network akin in scope and size to a natural deltaic network. Danube’s importance as a shipping route increased after the Crimean War in the 1850s; the European Danube Commission was charged with maintaining the Sulina distributary as a shipping channel until 1940s. In the same period, several canals were dug to aid fishing in lakes and bring freshwater to brackish lagoons. After World War II, Communist authorities dramatically increased the number of canals for fishing, fish-farming and reed harvesting. New data on sedimentation rates and estimates of sediment fluxes suggest that the intensive canalization in the second half of the 20th Century led to increased sediment deposition that compensated the decreasing sediment discharge linked to damming within the internal fluvial part of the delta; however, the external marine delta has become increasingly sediment starved during the same interval. We emphasize the similarities and contrasts between the “human-controlled” and natural deltaic channel networks of the Danube delta and discuss the sustainability of the delta as a sediment budget problem within a sea level rise context.

  3. What controls {delta}{sup 13}C(CH{sub 4}) and {delta}D(CH{sub 4}) of peat gases?

    SciTech Connect

    Waldron, S.; Fallick, A.E.; Hall, A.J.

    1996-10-01

    {delta}{sup 13}C(CH{sub 4}), {delta}{sup 13}C(CO{sub 2}) and {delta}D(CH{sub 4}) of bacteriogenic CH{sub 4} and CO{sub 2} from Ellergower Moss, a raised peat bog in S.W. Scotland were measured from gas samples collected in situ, from two profiles, at 1 m intervals, from the surface to a depth of 5 m. {delta}{sup 13}C(CH{sub 4}) had a mean of -76{plus_minus}3{per_thousand}, {delta}{sup 13}C(CO{sub 2}) had a mean of 3.8{plus_minus}5.3{per_thousand}, {delta}D(CH{sub 4}) had a mean of -294{plus_minus}39{per_thousand}. In each profile {delta}{sup 13}C(CH{sub 4}), {delta}{sup 13}C(CO{sub 2}) arid {delta}D(CH{sub 4}) showed a general gradation from isotopically heavy at 5 m depth to isotopically light at the surface. {delta}D(CH{sub 4}) suggested the presence of a boundary between 2-3 m as the measured values from 3-5 m were 52{plus_minus}18{per_thousand} heavier than samples from 0-2 m. Such a difference was also observed with {delta}{sup 13}C(CH{sub 4}) and {delta}{sup 13}C(CO{sub 2}) measurements. One possibility is that the observed differences in isotopic profiles within the bog were substrate controlled. However {delta}{sup 13}C and {delta}D measurements of peat and porewater reveal this to be unlikely. Rather {delta}{sup 13}C(CH{sub 4}), {delta}{sup 13}C(CO{sub 2}) and {delta}D(CH{sub 4}) may be controlled by gas storage and release mechanisms within the bog.

  4. A delta T-cell receptor deleting element transgenic reporter construct is rearranged in alpha beta but not gamma delta T-cell lineages.

    PubMed Central

    Shutter, J; Cain, J A; Ledbetter, S; Rogers, M D; Hockett, R D

    1995-01-01

    T cells can be divided into two groups on the basis of the expression of either alpha beta or gamma delta T-cell receptors (TCRs). Because the TCR delta chain locus lies within the larger TCR alpha chain locus, control of the utilization of these two receptors is important in T-cell development, specifically for determination of T-cell type: rearrangement of the alpha locus results in deletion of the delta coding segments and commitment to the alpha beta lineage. In the developing thymus, a relative site-specific recombination occurs by which the TCR delta chain gene segments are deleted. This deletion removes all D delta, J delta, and C delta genes and occurs on both alleles. This delta deletional mechanism is evolutionarily conserved between mice and humans. Transgenic mice which contain the human delta deleting elements and as much internal TCR delta chain coding sequence as possible without allowing the formation of a complete delta chain gene were developed. Several transgenic lines showing recombinations between deleting elements within the transgene were developed. These lines demonstrate that utilization of the delta deleting elements occurs in alpha beta T cells of the spleen and thymus. These recombinations are rare in the gamma delta population, indicating that the machinery for utilization of delta deleting elements is functional in alpha beta T cells but absent in gamma delta T cells. Furthermore, a discrete population of early thymocytes containing delta deleting element recombinations but not V alpha-to-J alpha rearrangements has been identified. These data are consistent with a model in which delta deletion contributes to the implementation of a signal by which the TCR alpha chain locus is rearranged and expressed and thus becomes an alpha beta T cell. PMID:8524269

  5. An integrated assessment framework for land subsidence in delta cities

    NASA Astrophysics Data System (ADS)

    Bucx, T. H. M.; van Ruiten, C. J. M.; Erkens, G.; de Lange, G.

    2015-11-01

    In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten by excessive groundwater extraction related to rapid urbanization and population growth. Without change, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other delta (and coastal) cities will sink below sea level. Increased flooding and also other widespread impacts of land subsidence result already in damage of billions of dollars per year. In order to gain insight in the complex, multi-sectoral aspects of subsidence, to raise awareness and to support decision making on appropriate adaptation strategies and measures, an Integrated Assessment Framework (IAF) for subsidence is introduced, illustrated by several (delta) case studies. Based on that a list of 10 generic key issues and possible solutions is presented in order to further develop and support a (generic) approach how to deal with subsidence in current and future subsidence-prone areas. For exchange of experiences and knowledge development.on subsidence in deltas the Delta Alliance, a knowledge network of deltas worldwide, can be supportive.

  6. Electronic Structure Calculations of delta-Pu Based Alloys

    SciTech Connect

    Landa, A; Soderlind, P; Ruban, A

    2003-11-13

    First-principles methods are employed to study the ground-state properties of {delta}-Pu-based alloys. The calculations show that an alloy component larger than {delta}-Pu has a stabilizing effect. Detailed calculations have been performed for the {delta}-Pu{sub 1-c}Am{sub c} system. Calculated density of Pu-Am alloys agrees well with the experimental data. The paramagnetic {yields} antiferromagnetic transition temperature (T{sub c}) of {delta}-Pu{sub 1-c}Am{sub c} alloys is calculated by a Monte-Carlo technique. By introducing Am into the system, one could lower T{sub c} from 548 K (pure Pu) to 372 K (Pu{sub 70}Am{sub 30}). We also found that, contrary to pure Pu where this transition destabilizes {delta}-phase, Pu{sub 3}Am compound remains stable in the antiferromagnetic phase that correlates with the recent discovery of a Curie-Weiss behavior of {delta}-Pu{sub 1-c}Am{sub c} at c {approx} 24 at. %.

  7. Sigma-delta cellular neural network for 2D modulation.

    PubMed

    Aomori, Hisashi; Otake, Tsuyoshi; Takahashi, Nobuaki; Tanaka, Mamoru

    2008-01-01

    Although sigma-delta modulation is widely used for analog-to-digital (A/D) converters, sigma-delta concepts are only for 1D signals. Signal processing in the digital domain is extremely useful for 2D signals such as used in image processing, medical imaging, ultrasound imaging, and so on. The intricate task that provides true 2D sigma-delta modulation is feasible in the spatial domain sigma-delta modulation using the discrete-time cellular neural network (DT-CNN) with a C-template. In the proposed architecture, the A-template is used for a digital-to-analog converter (DAC), the C-template works as an integrator, and the nonlinear output function is used for the bilevel output. In addition, due to the cellular neural network (CNN) characteristics, each pixel of an image corresponds to a cell of a CNN, and each cell is connected spatially by the A-template. Therefore, the proposed system can be thought of as a very large-scale and super-parallel sigma-delta modulator. Moreover, the spatio-temporal dynamics is designed to obtain an optimal reconstruction signal. The experimental results show the excellent reconstruction performance and capabilities of the CNN as a sigma-delta modulator. PMID:18215502

  8. Structure of the [delta]-opioid receptor bound to naltrindole

    SciTech Connect

    Granier, Sébastien; Manglik, Aashish; Kruse, Andrew C.; Kobilka, Tong Sun; Thian, Foon Sun; Weis, William I.; Kobilka, Brian K.

    2012-07-11

    The opioid receptor family comprises three members, the {mu}-, {delta}- and {kappa}-opioid receptors, which respond to classical opioid alkaloids such as morphine and heroin as well as to endogenous peptide ligands like endorphins. They belong to the G-protein-coupled receptor (GPCR) superfamily, and are excellent therapeutic targets for pain control. The {delta}-opioid receptor ({delta}-OR) has a role in analgesia, as well as in other neurological functions that remain poorly understood. The structures of the {mu}-OR and {kappa}-OR have recently been solved. Here we report the crystal structure of the mouse {delta}-OR, bound to the subtype-selective antagonist naltrindole. Together with the structures of the {mu}-OR and {kappa}-OR, the {delta}-OR structure provides insights into conserved elements of opioid ligand recognition while also revealing structural features associated with ligand-subtype selectivity. The binding pocket of opioid receptors can be divided into two distinct regions. Whereas the lower part of this pocket is highly conserved among opioid receptors, the upper part contains divergent residues that confer subtype selectivity. This provides a structural explanation and validation for the 'message-address' model of opioid receptor pharmacology, in which distinct 'message' (efficacy) and 'address' (selectivity) determinants are contained within a single ligand. Comparison of the address region of the {delta}-OR with other GPCRs reveals that this structural organization may be a more general phenomenon, extending to other GPCR families as well.

  9. Loss of organic matter from riverine particles in deltas

    SciTech Connect

    Keil, R.G.; Quay, P.D.; Richey, J.E.

    1997-04-01

    In order to examine the transport and burial of terrigenous organic matter along the coastal zones of large river systems, we assessed organic matter dynamics in coupled river/delta systems using mineral surface area as a conservative tracer for discharged riverine particulate organic matter (POM). Most POM in the rivers studied (n = 6) is tightly associated with suspended mineral materiaL e.g., it is sorbed to mineral surfaces. Average organic loadings in the Amazon River (0.67 - 0.14 Mg C m{sup -2}), the river for which we have the largest dataset, are approximately twice that of sedimentary minerals from the Amazon Delta (-0.35 mg C m{sup -2}). Stable carbon isotope analysis indicate that approximately two-thirds of the total carbon on the deltaic particles is terrestrial. The combined surface-normalized, isotope-distinguished estimate is that >70% of the Amazon fluvial POM is not buried in the delta consistent with other independent evidence. Losses of terrestrial POM have also been quantified for the river/delta systems of Columbia in the USA, Fly in New Guinea. and Huange-He in China. If the losses of riverine POM observed in these river/delta systems are representative of rivers worldwide, then the surface-constrained analyses point toward a global loss of fluvial POM in delta regions of {approximately}0.1 x 10{sup 15} g C y{sup -1}. 28 refs., 2 figs., 1 tab.

  10. The delta envelope: A technique for dose distribution comparison

    SciTech Connect

    Blanpain, Baptiste; Mercier, David

    2009-03-15

    The {gamma} index is a tool that compares a dose distribution with a reference distribution by combining dose-difference and distance-to-agreement criteria. It has been widely used for ten years despite its high computational cost. This cost is due to both a search process for each reference point and the necessity to remove overestimations caused by the discrete nature of dose grids. The method proposed in this paper is much faster since it avoids both these problems. It consists in computing the {delta} envelope formed by the {gamma} ellipsoids around the points of the reference distribution. This {delta} envelope provides dose-difference tolerances that are then used to create new indices, called the {delta} indices, that provide useful information to interpret the deviations. Applied to both 1D and 2D test cases and compared to the {gamma} index, the {delta} indices proved to be very accurate and intuitive. Their computational efficiency was evaluated on a 3D case: the {delta} envelope can be computed in 8 s on a 250x250x50 grid. Moreover it can be precomputed if the reference dose is known in advance. Then the {delta} indices are obtained in less than 2 s.

  11. High-Pressure Behavior of Perovskite: FeTiO[subscript 3] Dissociation into (Fe[subscript 1-delta]Ti[subscript delta])O and Fe[subscript 1+delta]Ti[subscript 2-delta]O[subscript 5

    SciTech Connect

    Wu, X.; Steinle-Neumann, G.; Narygina, O.; Kantor, I.; McCammon, C.; Prakapenka, V.; Swamy, V.; Dubrovinsky, L.

    2009-09-15

    The stability of perovskite-structured materials at high pressure and temperature is of fundamental interest in solid-state physics, chemistry, and the geosciences. As an alternative to decomposition into oxides or transformation of the CaIrO{sub 3} postperovskite structure, we observe in situ the breakdown of FeTiO{sub 3} perovskite into a (Fe{sub 1-{delta}},Ti{sub {delta}})O+Fe{sub 1+{delta}}Ti{sub 2-{delta}}O{sub 5} assemblage beyond 53 GPa and 2000 K. The high-pressure high-temperature phase of Fe{sub 1+{delta}}Ti{sub 2-{delta}}O{sub 5} with a new structure (space group C2/c) could be preserved on decompression to 9 GPa, and amorphizes under further pressure release. Our study demonstrates that perovskite-structured materials can undergo chemical changes and form complex oxides with new structures, rather than only transform to denser polymorphs or decompose to simple oxides.

  12. Isotope ratio mass spectrometry: delta13C and delta15 N analysis for tracing the origin of illicit drugs.

    PubMed

    Galimov, E M; Sevastyanov, V S; Kulbachevskaya, E V; Golyavin, A A

    2005-01-01

    Gas chromatography/combustion/mass spectrometry (GC-C-MS) and elemental analysis/mass spectrometry (EA-MS) techniques are proposed to estimate delta(13)C and delta(15)N values in heroin, morphine, cocaine and hemp leaves, for the purposes of tracing the geographical origins of seized drugs. The values of isotope ratios for pure drugs and drugs with impurities were compared. It was demonstrated that large samples (up to 3 x 10(-6) g C) were combusted completely, so that the results obtained were valid. The data are considered to be an essential supplement to a wide-scale database designed specifically for the delta(13)C and delta(15)N values of drugs. The potential forensic and academic significance of the results is discussed. PMID:15832288

  13. Recent morphodynamics of the Indus delta shore and shelf

    NASA Astrophysics Data System (ADS)

    Giosan, Liviu; Constantinescu, Stefan; Clift, Peter D.; Tabrez, Ali R.; Danish, Muhammed; Inam, Asif

    2006-09-01

    In natural conditions, the Indus River had one of the largest sediment loads in the world, building an extensive delta on the high-energy coast of the Arabian Sea. However, water and sediment discharge have been drastically altered in the Indus since the early 1960s, when several barrages were built along the river to feed the world's largest irrigation system. A digital terrain model based on detailed 19th century surveys has been constructed to assess the morphology of the Indus shelf. Comparison of the digital terrain model to a 1950s Pakistani bathymetric survey allowed an estimation of the natural sedimentation regime before extensive human-induced changes. Digital analysis of the Indus delta coastline based on satellite imagery was used to explore the effects of the drastic decrease in sediment delivery following extensive dam building. The Indus Canyon is a dominant feature of the region dissecting the shelf to within 20 m water depth and 3.5 km of the coast. Theoretical considerations based on estimates of the relative importance of wave energy vs. fluvial sediment delivery suggest that the Indus delta should develop a mid-shelf subaqueous clinoform. Instead, the Indus shelf exhibits a compound clinoform morphology. A shallow delta front clinoform extends along the entire delta coast from the shoreline to the 10-25 m water depth. A mid-shelf clinoform developed probably as a prodelta clinoform between ˜30 and 90 m water depth. The advanced position of the mid-shelf clinoform east of the Indus Canyon might reflect either a prolonged sediment delivery from the Indus River in that area compared to the shelf west of the canyon or the presence of a relict pre-Holocene mid-shelf delta. A distinct lobe of the mid-shelf clinoform developed along the Kutch (Kachchh) coast probably as sediment advected alongshore was redeposited on the mid-shelf by strong offshore-directed tidal currents at the Gulf of Kutch mouth. Accumulation and erosion between 1895/96 and 1952

  14. Opposite role of delta 1- and delta 2-opioid receptors activated by endogenous or exogenous opioid agonists on the endogenous cholecystokinin system: further evidence for delta-opioid receptor heterogeneity.

    PubMed

    Noble, F; Fournie-Zaluski, M C; Roques, B P

    1996-12-01

    Using the mouse caudate-putamen, where delta-opioid receptor subtypes have been shown to regulate adenylyl cyclase activity, we show in this study that endogenous enkephalins inhibit enzyme activity through activation of delta 1- and delta 2-opioid receptors. Thus, naltriben or 7-benzylidenenaltrexone as well as the delta-selective antagonist naltrindole (mixed delta 1 and delta 2 antagonist) antagonized inhibition of adenylyl cyclase activity induced by methionine- or leucine-enkephalin, while the micro-antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) was without effect. Furthermore, we have previously shown that activation of delta-opioid receptors increases cholecystokinin release in the central nervous system, resulting in a potentiation of micro-opioid antinociceptive responses, and the respective role of delta 1- and delta 2-opioid receptors in this facilitatory effect has now been evaluated. Activation of delta 2-opioid receptors, either by endogenous enkephalins protected from catabolism by the complete enkephalin-degrading enzyme inhibitor N-((R,S)-2-benzyl-3((S)(2-amino-4-methyl-thio) butyldithio)-1-oxopropyl)-L-phenyl-alanine benzyl ester (RB 101), or by the delta 2-selective agonist Tyr-D-Ser(O-tert-butyl)-Gly-Phe-Leu-Thr(O-tert-butyl) (BUBU), potentiated micro-opioid antinociceptive responses in the hot-plate test in mice. This effect was antagonized by a selective cholecystokinin-A antagonist. Activation of delta 1-opioid receptors by endogenous opioid peptides decreased the micro-opioid responses. These results suggest that stimulation of delta 2-opioid receptors potentiates micro-opioid analgesia in the hot-plate test in mice through an increase in endogenous cholecystokinin release, while activation of delta 1-opioid receptors could decrease it. Thus, the pre-existing physiological balance between opioid and cholecystokinin systems seems to be modulated in opposite directions depending on whether delta 1- or delta 2-opioid receptors are

  15. Chimeras of Delta6-fatty acid and Delta8-sphingolipid desaturases.

    PubMed

    Libisch, B; Michaelson, L V; Lewis, M J; Shewry, P R; Napier, J A

    2000-12-29

    The Borago officinalis Delta6 fatty acid desaturase (Boofd6) shares 58% identity in its amino acid sequence with Boofd8, a Delta8 sphingolipid desaturase from the same plant species. In order to localise the distinct catalytic properties of Boofd6 and Boofd8 to individual regions within them, a set of chimeras of these two enzymes were constructed and expressed in yeast. Chimera 2 is different from the other chimeras and Boofd6 in that it did not have any detectable desaturase activity on 18 carbon fatty acids. However, it desaturated C16 palmitoleic and C14 myristoleic acid, and the conversion rate for the later one was more than three times higher than that of Boofd6. These results suggest that the predicted membrane helices 1 and 2 of Boofd6 are involved in forming the substrate-binding site. This site appears to place constraints on the chain length of fatty acid substrates, which is similar to hydrophobic substrate binding pockets. PMID:11162428

  16. Phase modulated magnetoelectric delta-E effect sensor for sub-nano tesla magnetic fields

    NASA Astrophysics Data System (ADS)

    Zabel, S.; Kirchhof, C.; Yarar, E.; Meyners, D.; Quandt, E.; Faupel, F.

    2015-10-01

    We present a resonant micromechanical magnetic field sensor, which utilizes the magnetically induced change in elastic modulus, i.e., the delta-E effect. The sensor is based on magnetoelectric thin film composites, resulting in high sensitivity at room temperature and at low frequencies. The cantilever is electrically excited and read out by a 2 μm AlN piezoelectric layer. Depending on its magnetization, the 2 μm thin film of amorphous (Fe90Co10)78Si12B10 changes its elasticity, which results in a shift of the cantilever's resonance frequency. The sensor is operated in the first or second transversal bending mode at 7.6 kHz or 47.4 kHz. With a limit of detection of 140 pTHz-0.5 at 20 Hz under a magnetic bias field and 1 nTHz-0.5 without external bias field, this sensor exceeds all comparable designs by one order of magnitude.

  17. Correlation of magnetoelectric and delta-E effects in ferromagnetic-piezoelectric layered composites

    NASA Astrophysics Data System (ADS)

    Laletin, V. M.; Srinivasan, G.; Bichurin, M. I.

    2005-03-01

    Magnetoelectric (ME) coupling and its dependence on delta-E-effect have been studied in trilayers of ferromagnetic metals and lead zirconate titanate (PZT). Measurements on samples with PZT and Fe, Co, Ni or permendur (an alloy of Co-Fe-V) show evidence for strong ME interactions. Our theoretical model for bias magnetic field H dependence of ME effect predicts contributions due to two mechanisms: variation of piezomagnetic and compliance coefficients with H. The individual contributions from the two sources can be measured in the electromechanical resonance (EMR) region for the composite. Data on frequency dependence of ME coefficient reveal a giant coupling at electromechanical resonance (EMR), at 200-300 kHz for radial modes and at ˜2.7 MHz for thickness modes. Variation of compliance coefficients with H (delta-E-effect) results in a frequency shift of peak ME voltage coefficient. Theoretical profiles of ME coefficient vs. frequency agree with the data. These results are of importance for the design of signal processing devices that requires fine tuning. 1. M. I. Bichurin, D.A. Filippov, V. M. Petrov, V. M. Laletin, N. Paddubnaya, and G. Srinivasan, Phys. Rev. B 68, 132408 (2003). - supported by grants from the Russian Ministry of Education (Å02-3.4-278), the Universities of Russia Foundation (UNR 01.01.026) and the National Science Foundation (DMR-0302254).

  18. Harding Iceland spar: a new delta 18O-delta 13C carbonate standard for hydrothermal minerals.

    USGS Publications Warehouse

    Landis, G.P.

    1983-01-01

    An isotopically homogenous calcite, Iceland spar from the Iceberg claim, near the Harding pegmatite of N New Mexico, has delta 18O +11.78 + or - 0.07per mille (=+22.15per mille for CO2) and delta 13C -4.80 + or - 0.02per mille and has been prepared in quantities suitable for use as a working standard in MS.-R.A.H.

  19. A Conceptual Framework for Analyzing Deltas as Coupled Social-Ecological Systems: An example from the Amazon Delta

    NASA Astrophysics Data System (ADS)

    Brondizio, E.; Vogt, N. D.; Hetrick, S.; da Costa, S. M. F.; Anthony, E.

    2015-12-01

    At the nexus of watersheds, land, coastal areas, oceans, and human settlements, river delta regions pose specific challenges to environmental governance and sustainability. Using the Amazon Delta (AD) as our focus we reflect on the challenges created by the high degree of functional interdependencies shaping social-ecological dynamics of delta regions. The article introduces the initial design of an integrated conceptual framework to analyze delta regions as coupled social-ecological systems (SES). The first component of the framework is used to provide integrated definitions of delta regions according to a problem and/or collective action dilemma. Five different systematic components are suggested: social-economic systems, governance systems, ecosystems-resource systems, topographic-hydrological systems, and oceanic-climate systems. The second component of the framework presents a strategy for nested social ecological analysis to examine collective action situations in delta regions from local to regional and basin levels. The article provides illustrative applications of the framework to the Amazon Delta. First, it is used to define the AD region as a coupled, multi-level SES. We further proposed a definition of what we call the core SES of the AD. We then utilize the framework to diagnose an example collective action problem related to the impacts of urban growth and pollution on small-scale fishing resources. We argue that the functional interdependencies characteristic of delta regions require new approaches to understand, diagnose, and evaluate the current and future impact of social and environmental changes and potential solutions to the sustainability dilemmas characteristic of these regions.

  20. Architecture of a Coarse-Grained Upper Middle Cambrian Alluvial Delta Dominated by Braidplain and Gilbert-Style Delta Components

    NASA Astrophysics Data System (ADS)

    Pound, K. S.

    2014-12-01

    The ~500-m thick upper Middle Cambrian Lockett Conglomerate was deposited as part of an alluvial delta that includes Gilbert-type mega-crossbeds as well as braidplain conglomerates, and was constructed across an accretionary prism. Internal Lockett Conglomerate architecture indicates at least three phases of progradation are recorded by Gilbert-type, delta-front deposits that are separated by delta-top distributaries and/or braidplain deposits, all of which form discontinuous sheets and lenses, and record aggradation. Evaluation of sedimentary features (particle size and organization, bedding features) allows identification of eight facies within the Lockett Conglomerate; sedimentary features were used to infer transportational and depositional mechanisms. Conglomerate facies HL-1 - HL-8 were assigned to one or more of the following depositional associations: Beachface/shoreface, Deltafront, Alluvial fan, Braidplain (fluvial, unchannelized), Delta-top distributaries, and Mouth-bars. A series of Depositional Packages was identified, and mapped; integration with measured sections allowed development of a facies model for an alluvial delta in which the subaerial component is dominated by the braidplain association, and the subaqueous component by the (Gilbert-type) deltafront association as well as the delta-top distributary and mouthbar associations. Locally, the beachface association marks the transition between the subaqueous and subaerial components of the alluvial delta. Alluvial fan deposits are absent, but the rounded pebbles, cobbles and boulders with a new and distinctive provenance signature indicate derivation from a newly exposed igneous and metamorphic basement, and abrasion during transport through the fluvial (braidplain) system prior to deposition as part of the alluvial delta.

  1. Purification and Properties of Staphylococcal Delta Hemolysin

    PubMed Central

    Kreger, Arnold S.; Kim, Kwang-Shin; Zaboretzky, Frank; Bernheimer, Alan W.

    1971-01-01

    Large amounts (200 mg per liter of culture supernatant fluid) of highly purified staphylococcal soluble delta hemolysin were obtained by adsorption to and selective elution from hydroxyapatite followed by exhaustive dialysis against water, concentration by polyvinylpyrrolidone or polyethylene glycol 20,000 dialysis, and a final water dialysis. No carbohydrate, phosphorus, or inactive 280-nm absorbing material was detected in the preparation; however, analysis by density gradient centrifugation, gel filtration, analytical ultracentrifugation, carboxymethyl cellulose chromatography, polyacrylamide disc gel electrophoresis, isoelectric focusing, and electron microscopy revealed that the lysin was molecularly heterogeneous. The preparation contained an acidic fibrous lysin (S20,w of 11.9) and a basic lysin component composed of a population of granular aggregates of various sizes, with a maximum S20,w of approximately 4.9. No other staphylococcal products were detected in the preparation. The lysin was active against erythrocytes from many animal species and acted synergistically with staphylococcal beta hemolysin against sheep erythrocytes. It was soluble in chloroform-methanol (2:1), was inactivated by various phospholipids, normal sera, and proteolytic enzymes, but was partially resistant to heat inactivation. Activity was not affected by Ca2+, Mg2+, citrate, ethylenediaminetetraacetic acid, or cysteine. The lysin preparation also disrupted bacterial protoplasts and spheroplasts, erythrocyte membranes, lysosomes, and lipid spherules, was growth-inhibitory for certain bacteria, and clarified egg yolk-agar. Large amounts produced dermonecrosis in rabbits and guinea pigs. The minimum lethal intravenous dose for mice and guinea pigs was approximately 110 and 30 mg/kg, respectively. Images PMID:16557995

  2. Recombinative events of the T cell antigen receptor delta gene in peripheral T cell lymphomas.

    PubMed Central

    Kanavaros, P; Farcet, J P; Gaulard, P; Haioun, C; Divine, M; Le Couedic, J P; Lefranc, M P; Reyes, F

    1991-01-01

    Recombinative events of the T cell antigen receptor (TCR) delta-chain gene were studied in 37 cases of peripheral T cell lymphoma (PTCL) and related to their clinical presentation and the expression of the alpha beta or gamma delta heterodimers as determined by immunostaining of frozen tissue samples. There were 22 cases of alpha beta, 5 cases of gamma delta, and 10 cases of silent TCR expressing neither the alpha beta nor gamma delta TCR. 5 different probes were used to examine the delta locus. The 22 cases of alpha beta PTCL displayed biallelic and monoallelic deletions; a monoallelic V delta 1 J delta 1 rearrangement was observed in 1 case and a monoallelic germ line configuration in 7 cases. The 5 cases of gamma delta PTCL displayed biallelic rearrangements: the productive rearrangements could be ascribed to V delta 1J delta 1 joining in 3 cases and VJ delta 1 joining in 2 cases according to the combined pattern of DNA hybridization with the appropriate probes and of cell reactivity with the TCR delta-1, delta TCS-1, and anti-V delta 2 monoclonal antibodies. In the VJ delta 1 joining, the rearranged V segments were located between V delta 1 and V delta 2. Interestingly, in the third group of 10 cases of silent PTCL, 5 cases were found to have a TCR gene configuration identical to that in the TCR alpha beta PTCL, as demonstrated by biallelic delta gene deletion. These 5 cases were CD3 positive. The 5 remaining cases showed a monoallelic delta gene rearrangement with a monoallelic germ line configuration in 4 and a monoallelic deletion in 1. Four of these cases were CD3 negative, which was consistent with an immature genotype the TCR commitent of which could not be ascertained. Finally, TCR gamma delta PTCL consisted of a distinct clinical morphological and molecular entity whereas TCR alpha beta and silent PTCL had a similar presentation. Images PMID:1991851

  3. Assessment of Factors Contributing to Health Outcomes in the Eight States of the Mississippi Delta Region

    PubMed Central

    Jovaag, Amanda; Catlin, Bridget B.; Rodock, Matthew; Park, Hyojun

    2016-01-01

    Introduction The objective of this observational study was to examine the key contributors to health outcomes and to better understand the health disparities between Delta and non-Delta counties in 8 states in the Mississippi River Delta Region. We hypothesized that a unique set of contributors to health outcomes in the Delta counties could explain the disparities between Delta and non-Delta counties. Methods Data were from the 2014 County Health Rankings for counties in 8 states (Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee). We used the Delta Regional Authority definition to identify the 252 Delta counties and 468 non-Delta counties or county equivalents. Information on health factors (eg, health behaviors, clinical care) and outcomes (eg, mortality) were derived from 38 measures from the 2014 County Health Rankings. The contributions of health factors to health outcomes in Delta and non-Delta counties were examined using path analysis. Results We found similarities between Delta counties and non-Delta counties in the health factors (eg, tobacco use, diet and exercise) that significantly predicted the health outcomes of self-rated health and low birthweight. The most variation was seen in predictors of mortality; however, Delta counties shared 2 of the 3 significant predictors (ie, community safety and income) of mortality with non-Delta counties. On average across all measures, values in the Delta were 16% worse than in the non-Delta and 22% worse than in the rest of the United States. Conclusion The health status of Delta counties is poorer than that of non-Delta counties because the health factors that contribute to health outcomes in the entire region are worse in the Delta counties, not because of a unique set of health predictors. PMID:26940300

  4. Quantifying the signature of sediment composition on the topologic and dynamic complexity of river delta channel networks and inferences toward delta classification

    NASA Astrophysics Data System (ADS)

    Tejedor, Alejandro; Longjas, Anthony; Caldwell, Rebecca; Edmonds, Douglas A.; Zaliapin, Ilya; Foufoula-Georgiou, Efi

    2016-04-01

    Deltas contain complex self-organizing channel networks that nourish the surface with sediment and nutrients. Developing a quantitative understanding of how controlling physical mechanisms of delta formation relate to the channel networks they imprint on the landscape remains an open problem, hindering further progress on quantitative delta classification and understanding process from form. Here we isolate the effect of sediment composition on network structure by analyzing Delft3D river-dominated deltas within the recently introduced graph-theoretic framework for quantifying complexity of delta channel networks. We demonstrate that deltas with coarser incoming sediment tend to be more complex topologically (increased number of pathways) but simpler dynamically (reduced flux exchange between subnetworks) and that once a morphodynamic steady state is reached, complexity also achieves a steady state. By positioning simulated deltas on the so-called TopoDynamic complexity space and comparing with field deltas, we propose a quantitative framework for exploring complexity toward systematic inference and classification.

  5. Plasticity and grain boundary structure of {delta}{sub 1k} and {delta}{sub 1p} intermetallic phases in the Fe-Zn system

    SciTech Connect

    Hong, M.H.; Saka, H.

    1997-10-01

    Two polycrystalline specimens of single phase with composition of 87.6 at.% Zn({delta}{sub 1k}) and 90.6 at.% Zn({delta}{sub 1p} phase) in the Fe-Zn system have been prepared and deformed in compression between 200 C and 650 C. Below 350 C the {delta}{sub 1k} phase is brittle, but above 400 C it is ductile. By contrast, the {delta}{sub 1p} phase never showed plasticity at any deformation temperature and strain rate. The microstructures of {delta}{sub 1k} and {delta}{sub 1p} phases were studied by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technique and correlated with the difference in plasticity. The difference in grain boundary structure between {delta}{sub 1k} and {delta}{sub 1p} phases was found to be the primary reason for the observed difference in plasticity.

  6. Investigation of leading-edge flap performance on delta and double-delta wings at supersonic speeds

    NASA Technical Reports Server (NTRS)

    Covell, Peter F.; Wood, Richard M.; Miller, David S.

    1987-01-01

    An investigation of the aerodynamic performance of leading-edge flaps on three clipped delta and three clipped double-delta wing planforms with aspect ratios of 1.75, 2.11, and 2.50 was conducted in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.60, 1.90, and 2.16. A primary set of fullspan leading-edge flaps with similar root and tip chords were investigated on each wing, and several alternate flap planforms were investigated on the aspect-ratio-1.75 wings. All leading-edge flap geometries were effective in reducing the drag at lifting conditions over the range of wing aspect ratios and Mach numbers tested. Application of a primary flap resulted in better flap performance with the double-delta planform than with the delta planform. The primary flap geometry generally yielded better performance than the alternate flap geometries tested. Trim drag due to flap-induced pitching moments was found to reduce the leading-edge flap performance more for the delta planform than for the double-delta planform. Flow-visualization techniques showed that leading-edge flap deflection reduces crossflow shock-induced separation effects. Finally, it was found that modified linear theory consistently predicts only the effects of leading-edge flap deflection as related to pitching moment and lift trends.

  7. Anadromous salmonids in the Delta: New science 2006–2016

    USGS Publications Warehouse

    Perry, Russell W.; Buchanan, Rebecca A.; Brandes, Patricia L.; Burau, Jon R.; Israel, Joshua A

    2016-01-01

    As juvenile salmon enter the Sacramento–SanJoaquin River Delta (“the Delta”) they disperse among its complex channel network where they are subject to channel-specific processes that affect their rate of migration, vulnerability to predation, feeding success, growth rates, and ultimately, survival. In the decades before 2006, tools available to quantify growth, dispersal, and survival of juvenile salmon in this complex channel network were limited.Fortunately, thanks to technological advances such as acoustic telemetry and chemical and structural otolith analysis, much has been learned over the past decade about the role of the Delta in the life cycle of juvenile salmon. Here, we review new science between 2006and 2016 that sheds light on how different life stages and runs of juvenile salmon grow, move, and survive in the complex channel network of the Delta. One of the most important advances during the past decade has been the widespread adoption of acoustic telemetry techniques. Use of telemetry has shed light on how survival varies among alternative migration routes and the proportion of fish that use each migration route. Chemical and structural analysis of otoliths has provided insights about when juveniles left their natal river and provided evidence of extended rearing in the brackish or saltwater regions of the Delta. New advancements in genetics now allow individuals captured by trawls to be assigned to specific runs. Detailed information about movement and survival in the Delta has spurred development of agent-based models of juvenile salmon that are coupled to hydrodynamic models. Although much has been learned, knowledge gaps remain about how very small juvenile salmon (fry and parr) use the Delta. Understanding how all life stages of juvenile salmon grow, rear, and survive in the Delta is critical for devising management strategies that support a diversity of life history strategies.

  8. Delta CK-MB outperforms delta troponin I at 2 hours during the ED rule out of acute myocardial infarction.

    PubMed

    Fesmire, F M

    2000-01-01

    It has been shown that a rise in creatine kinase MB bank (CK-MB) of > or = + 1.6 ng/mL in 2 hours is more sensitive and equally specific for detection of acute myocardial infarction (AMI) as compared with a 2-hour CK-MB > or = 6 ng/mL during the emergency department (ED) evaluation of chest pain. Because cardiac specific troponin I (cTnI) is thought to have similar early release kinetics as compared with CK-MB mass, we undertook a retrospective cohort study in 578 chest pain patients whose baseline CK-MB and cTnI was less than two times the hospital's upper limits of normal and who underwent a 2-hour CK-MB and cTnI to compare sensitivities and specificities of the 2-hour delta CK-MB (deltaCK-MB) and delta cTnI (delta cTnI) for AMI and 30-day Adverse Outcome (AO). Thirty day AO was defined as AMI, life-threatening complication, death, or percutaneous transluminal coronary angioplasty (PTCA)/coronary artery bypass graft (CABG) within 30 days of ED presentation. Optimum delta values were determined by choosing the smallest cutoff value greater than the assay precision where the deltaCK-MB and delta cTnI had a positive likelihood ratio for 30-day AO of > or = 15. A deltaCK-MB > or = +1.5 ng/mL was more sensitive than a deltaTnI > or = +0.2 ng/mL for AMI (87.7% versus 61.4%; P < .0005) and 30-day AO (56.7% versus 42.3%; P < .005). There were no differences in specificities for AMI and 30-day AO. Combining the two tests (MBdelta > or = +1.5 ng/mL and/or a deltaTnI > or = +0.2 ng/mL) resulted in an incremental increase in sensitivity of 89.5% for AMI and 61.9% for AO (P < .005). Patients with either a rise in CK-MB of > or = +1.5 ng/mL or rise in cTnI of > or = +0.2 ng/mL in 2 hours should receive consideration for aggressive antiischemic therapy and further diagnostic testing before making an exclusionary diagnosis of nonischemic chest pain. PMID:10674522

  9. Winds and accretion in delta Sagittae

    NASA Astrophysics Data System (ADS)

    Eaton, Joel A.; Hartkopf, William I.; McAlister, Harold A.; Mason, Brian D.

    1995-04-01

    The ten-year binary delta Sge (M2 Ib-II+B9.5 V) is a zeta Aur binary containing an abnormally cool component. Combining our analysis of the system as a visual binary with Batten's radial-velocity solution leads to the following properties: i = 40 deg, a = 51 mas = 8.83 A.U. = 1893 solar radius, hence d = 173 pc; MB = 2.9 solar mass and MM = 3.8 solar mass; and RB = 2.6 solar radius and RM = 152 solar radius. This interpretation of the orbit places the M supergiant on the asymptotic giant branch. We have collected ultraviolet spectra throughout the star's 1980-90 orbit, concentrated around the conjuction of 1990. The wind of the M giant appears in these as narrow shell lines of singly ionized metals, chiefly Fe II, with P-Cyg profiles at many phases, which show the slow variation in strength expected for the orbit but no pronounced atmospheric eclipse. The terminal velocity of the wind is 16-18 km/s, and its excitation temperature is approximately 10,000 K. Most of the broadening of the wind lines is caused by differential expansion of the atmosphere, with (unmeasurably) low turbulent velocities. Nontheless, the mass loss rate (1.1 +/- 0.4 X 10 -8 solar mas/yr) is almost the same as found previously by Reimers and Schroder for very different assumptions about the velocity structure. Also seen in the spectrum throughout the orbit are the effects of a variable, high-speed wind as well as evidence for accretion onto the B9.5 star. This high-speed wind absorbs in species of all ionization stages observed, e. g., C II, Mg II, Al III, SI IV, C IV, and has a terminaal velocity in the range 200-450 km/s. We presume this wind originates at the B dwarf, not the M supergiant, and speculate that it comes from an accretion disk, as suggested by recent models of magnetically moderated accretion. Evidence for accretion is redshifted absorption in the same transitions formed in the high-speed wind, as well as broad emission lines of singly ionized metals. This emission seems to be

  10. Winds and accretion in delta Sagittae

    NASA Technical Reports Server (NTRS)

    Eaton, Joel A.; Hartkopf, William I.; Mcalister, Harold A.; Mason, Brian D.

    1995-01-01

    The ten-year binary delta Sge (M2 Ib-II+B9.5 V) is a zeta Aur binary containing an abnormally cool component. Combining our analysis of the system as a visual binary with Batten's radial-velocity solution leads to the following properties: i = 40 deg, a = 51 mas = 8.83 A.U. = 1893 solar radius, hence d = 173 pc; M(sub B) = 2.9 solar mass and M(sub M) = 3.8 solar mass; and R(sub B) = 2.6 solar radius and R(sub M) = 152 solar radius. This interpretation of the orbit places the M supergiant on the asymptotic giant branch. We have collected ultraviolet spectra throughout the star's 1980-90 orbit, concentrated around the conjuction of 1990. The wind of the M giant appears in these as narrow shell lines of singly ionized metals, chiefly Fe II, with P-Cyg profiles at many phases, which show the slow variation in strength expected for the orbit but no pronounced atmospheric eclipse. The terminal velocity of the wind is 16-18 km/s, and its excitation temperature is approximately 10,000 K. Most of the broadening of the wind lines is caused by differential expansion of the atmosphere, with (unmeasurably) low turbulent velocities. Nontheless, the mass loss rate (1.1 +/- 0.4 X 10 (exp -8) solar mas/yr) is almost the same as found previously by Reimers and Schroder for very different assumptions about the velocity structure. Also seen in the spectrum throughout the orbit are the effects of a variable, high-speed wind as well as evidence for accretion onto the B9.5 star. This high-speed wind absorbs in species of all ionization stages observed, e. g., C II, Mg II, Al III, SI IV, C IV, and has a terminaal velocity in the range 200-450 km/s. We presume this wind originates at the B dwarf, not the M supergiant, and speculate that it comes from an accretion disk, as suggested by recent models of magnetically moderated accretion. Evidence for accretion is redshifted absorption in the same transitions formed in the high-speed wind, as well as broad emission lines of singly ionized

  11. Remote Sensing Study of The Volga Delta Flooding Dynamics

    NASA Astrophysics Data System (ADS)

    Tsitsenko, K. V.; Shalygin, A. L.

    The Volga Delta is the lowest part of the Volga basin where the river divides to hun- dreds of branches of different scales, forming a great amount of islands and permanent or temporary lakes. Considerable part of these islands can be covered temporarily by the river water during the spring-flood, or for a long time by the Caspian Sea water during the high Sea level stages. The main part of the Volga runoff losses (in average about 10 km3/year) takes place in the Delta. These losses depend on the proportion of land and water areas, depending in its turn on the Caspian Sea level and on the Volga river flow phase. The rice irrigation, which requires great amounts of water, causes considerable anthropogenic runoff losses in the Delta. Remote sensing study of the Volga Delta was carried out to define the following: - The Sea border of the Delta and its dynamics depending on the Sea level; - Water surface area dynamics in the Delta depending on the Volga hydrological phase and the spring flood volume; - The inter-year and long-term landuse dynamics in the Delta. 13 digital satellite images of the Delta from 1970s - 1990s were used for realization of the study: 3 Landsat-MSS (USA, 4 spectral bands), 4 Landsat-TM (USA, 7 bands) and 6 Resource-01 (Russia, 2-4 bands), chosen on a principle of scope both all amplitude of the Sea level and various phases of the Volga hydrological regime. Classification of the images was car- ried out by means of the GIS-system ILWIS, using both original spectral bands and calculated artificial bands, such as NDVI, SWCI, LWCI, etc. From 4 to 5 bands with the least correlation were used for classification of each image. Analysis of classifica- tion results has shown that water surface in the Delta during low-flow period occupied 5-7% of the area, sharply growing (to 50%) during the spring high water. The area of half-submerged reeds, located along the Sea coast, reduced from 34% in 1970s to 20- 24% in 1980s, and by 1995 the significant part of

  12. Preparing the Dutch delta for future droughts: model based support in the national Delta Programme

    NASA Astrophysics Data System (ADS)

    ter Maat, Judith; Haasnoot, Marjolijn; van der Vat, Marnix; Hunink, Joachim; Prinsen, Geert; Visser, Martijn

    2014-05-01

    Keywords: uncertainty, policymaking, adaptive policies, fresh water management, droughts, Netherlands, Dutch Deltaprogramme, physically-based complex model, theory-motivated meta-model To prepare the Dutch Delta for future droughts and water scarcity, a nation-wide 4-year project, called Delta Programme, is established to assess impacts of climate scenarios and socio-economic developments and to explore policy options. The results should contribute to a national adaptive plan that is able to adapt to future uncertain conditions, if necessary. For this purpose, we followed a model-based step-wise approach, wherein both physically-based complex models and theory-motivated meta-models were used. First step (2010-2011) was to make a quantitative problem description. This involved a sensitivity analysis of the water system for drought situations under current and future conditions. The comprehensive Dutch national hydrological instrument was used for this purpose and further developed. Secondly (2011-2012) our main focus was on making an inventory of potential actions together with stakeholders. We assessed efficacy, sell-by date of actions, and reassessed vulnerabilities and opportunities for the future water supply system if actions were (not) taken. A rapid assessment meta-model was made based on the complex model. The effects of all potential measures were included in the tool. Thirdly (2012-2013), with support of the rapid assessment model, we assessed the efficacy of policy actions over time for an ensemble of possible futures including sea level rise and climate and land use change. Last step (2013-2014) involves the selection of preferred actions from a set of promising actions that meet the defined objectives. These actions are all modeled and evaluated using the complex model. The outcome of the process will be an adaptive management plan. The adaptive plan describes a set of preferred policy pathways - sequences of policy actions - to achieve targets under

  13. DeltaA/DeltaD regulate multiple and temporally distinct phases of notch signaling during dopaminergic neurogenesis in zebrafish.

    PubMed

    Mahler, Julia; Filippi, Alida; Driever, Wolfgang

    2010-12-01

    Dopaminergic neurons develop at distinct anatomical sites to form some of the major neuromodulatory systems in the vertebrate brain. Despite their relevance in neurodegenerative diseases and the interests in reconstitutive therapies from stem cells, mechanisms of the neurogenic switch from precursor populations to dopaminergic neurons are not well understood. Here, we investigated neurogenesis of different dopaminergic and noradrenergic neuron populations in the zebrafish embryo. Birth-dating analysis by EdU (5-ethynyl-2'-deoxyuridine) incorporation revealed temporal dynamics of catecholaminergic neurogenesis. Analysis of Notch signaling mutants and stage-specific pharmacological inhibition of Notch processing revealed that dopaminergic neurons form by temporally distinct mechanisms: dopaminergic neurons of the posterior tuberculum derive directly from neural plate cells during primary neurogenesis, whereas other dopaminergic groups form in continuous or wavelike neurogenesis phases from proliferating precursor pools. Systematic analysis of Notch ligands revealed that the two zebrafish co-orthologs of mammalian Delta1, DeltaA and DeltaD, control the neurogenic switch of all early developing dopaminergic neurons in a partially redundant manner. DeltaA/D may also be involved in maintenance of dopaminergic precursor pools, as olig2 expression in ventral diencephalic dopaminergic precursors is affected in dla/dld mutants. DeltaA/D act upstream of sim1a and otpa during dopaminergic specification. However, despite the fact that both dopaminergic and corticotropin-releasing hormone neurons derive from sim1a- and otpa-expressing precursors, DeltaA/D does not act as a lineage switch between these two neuronal types. Rather, DeltaA/D limits the size of the sim1a- and otpa-expressing precursor pool from which dopaminergic neurons differentiate. PMID:21148001

  14. ThemeDelta: Dynamic Segmentations over Temporal Topic Models.

    PubMed

    Gad, Samah; Javed, Waqas; Ghani, Sohaib; Elmqvist, Niklas; Ewing, Tom; Hampton, Keith N; Ramakrishnan, Naren

    2015-05-01

    We present ThemeDelta, a visual analytics system for extracting and visualizing temporal trends, clustering, and reorganization in time-indexed textual datasets. ThemeDelta is supported by a dynamic temporal segmentation algorithm that integrates with topic modeling algorithms to identify change points where significant shifts in topics occur. This algorithm detects not only the clustering and associations of keywords in a time period, but also their convergence into topics (groups of keywords) that may later diverge into new groups. The visual representation of ThemeDelta uses sinuous, variable-width lines to show this evolution on a timeline, utilizing color for categories, and line width for keyword strength. We demonstrate how interaction with ThemeDelta helps capture the rise and fall of topics by analyzing archives of historical newspapers, of U.S. presidential campaign speeches, and of social messages collected through iNeighbors, a web-based social website. ThemeDelta is evaluated using a qualitative expert user study involving three researchers from rhetoric and history using the historical newspapers corpus. PMID:26357213

  15. Prenatal lead exposure, delta-aminolevulinic acid, and schizophrenia.

    PubMed Central

    Opler, Mark G A; Brown, Alan S; Graziano, Joseph; Desai, Manisha; Zheng, Wei; Schaefer, Catherine; Factor-Litvak, Pamela; Susser, Ezra S

    2004-01-01

    Schizophrenia is a severe mental disorder of unknown etiology. Recent reports suggest that a number of environmental factors during prenatal development may be associated with schizophrenia. We tested the hypothesis that environmental lead exposure may be associated with schizophrenia using archived serum samples from a cohort of live births enrolled between 1959 and 1966 in Oakland, California. Cases of schizophrenia spectrum disorder were identified and matched to controls. A biologic marker of lead exposure, delta-aminolevulinic acid (delta-ALA), was determined in second-trimester serum samples of 44 cases and 75 controls. delta-ALA was stratified into high and low categories, yielding 66 subjects in the high category, corresponding to a blood lead level (BPb) greater than or equal to 15 micro g/dL, and 53 in the low category, corresponding to BPb less than 15 micro g/dL. Using logistic regression, the odds ratio (OR) for schizophrenia associated with higher delta-ALA was 1.83 [95% confidence interval (CI), 0.87-3.87; p = 0.1]. Adjusting for covariates gave an OR of 2.43 (95% CI, 0.99-5.96; p = 0.051). This finding suggests that the effects of prenatal exposure to lead and/or elevated delta-ALA may extend into later life and must be further investigated as risk factors for adult psychiatric diseases. PMID:15064159

  16. Transmembrane topography of the nicotinic acetylcholine receptor delta subunit.

    PubMed

    McCrea, P D; Popot, J L; Engelman, D M

    1987-12-01

    Current folding models for the nicotinic acetylcholine receptor (AChR) predict either four or five transmembrane segments per subunit. The N-terminus of each subunit is almost certainly extracellular. We have tested folding models by determining biochemically the cellular location of an intermolecular disulfide bridge thought to lie at the delta subunit C-terminus. Dimers of AChR linked through the delta-delta bridge were prepared from Torpedo marmorata and T.californica electric organ. The disulfide's accessibility to hydrophilic reductants was tested in a reconstituted vesicle system. In right-side-out vesicles (greater than 95% ACh binding sites outwards), the bridge was equally accessible whether or not vesicles had been disrupted by freeze--thawing or by detergents. Control experiments based on the rate of reduction of entrapped diphtheria toxin and measurements of radioactive reductant efflux demonstrated that the vesicles provide an adequate permeability barrier. In reconstituted vesicles containing AChR dimers in scrambled orientations, right-side-out dimers were reduced to monomers three times more rapidly than inside-out dimers, consistent with the measured rate of reductant permeation. These observations indicate that in reconstituted vesicles the delta-delta disulfide bridge lies in the same aqueous space as the ACh binding sites. They are most easily reconciled with folding models that propose an even number of transmembrane crossing per subunit. PMID:3428268

  17. The petroleum systems of the Ogooue Delta, Offshore Gabon

    SciTech Connect

    Katz, B.J.; Dawson, W.C.; Liro, L.M.; Robison, V.D.; Stone-Braker, J.D.

    1996-08-01

    An analysis of the petroleum geology of the Ogooue Delta region reveals the presence of two independent petroleum systems. The first system appears to have been generated from a pre-Cenomanian restricted marine source. These oils are largely reservoired in Batanga Formation sandstones (Maastrichtian) and are deposited principally along the southern margin of the delta. The second system appears to have been generated from the Azile and Anguille Formations (Senonian). These Upper Cretaceous oils are reservoired principally within Anguille reservoirs. These accumulations appear geographically less restricted, but appear most concentrated within the northern portion of the delta. The geographic distribution of the two systems appears to be controlled by several factors including the distribution of the oil-prone source, the nature of migration network, and the level of thermal maturity. The pre-Cenomanian system appears to have a more effective mechanism for vertical migration than the Azile-Anguille sourced system. It is unclear as to why differences in the migration network should exist within a single delta complex. Although the two systems have different source rocks they both share one major controlling factor. In both cases the areal limit of the petroleum system is constrained by thermal maturation. The overburden associated with the delta complex provided for the appropriate levels of thermal maturation. Modeling results suggest that the pre-Cenomanian system began generating liquid hydrocarbons during the Oligocene. The Senonian system began generating hydrocarbons during the Miocene. Both systems are still actively generating hydro- carbons.

  18. Delta hepatitis: molecular biology and clinical and epidemiological features.

    PubMed Central

    Polish, L B; Gallagher, M; Fields, H A; Hadler, S C

    1993-01-01

    Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection. PMID:8358704

  19. Bifurcations and delta planform stability: the role of substrate cohesion

    NASA Astrophysics Data System (ADS)

    Royce, J.; Parsons, D. R.; Best, J.; Edmonds, D. A.; Slingerland, R. L.

    2013-12-01

    The stability of channel bifurcations is central to controlling the planform evolution of deltas and determining the split of flow and sediment discharge between the distributary channels. Recent research has examined the role of grain size in influencing delta planform morphology and shown radically different planform geometries being produced in finer grain sizes. Deltas also frequently expand through channel progradation into underlying pro-deltaic deposits that are often finer grained, and more cohesive, than the sediment within the distributary channels. Here, we display data from multibeam echo sounder surveys of the Wax Lake delta, LO, USA, that shown incision at the major bifurcations into underlying cohesive material. These cohesive deposits develop an array of erosive sedimentary bedforms, including flutes and longitudinal scours. The morphology of these erosive features will be examined in relation to past work on erosive bedforms in muds and bedrock. These bifurcations also appear stable in their location and this suggests such incision may provide a way to pin these morphological nodes that become fixed in their position and then distribute sediment from these points. Incision into such underlying sediments may thus be key in the planform evolution of such deltas.

  20. Martian stepped-delta formation by rapid water release.

    PubMed

    Kraal, Erin R; van Dijk, Maurits; Postma, George; Kleinhans, Maarten G

    2008-02-21

    Deltas and alluvial fans preserved on the surface of Mars provide an important record of surface water flow. Understanding how surface water flow could have produced the observed morphology is fundamental to understanding the history of water on Mars. To date, morphological studies have provided only minimum time estimates for the longevity of martian hydrologic events, which range from decades to millions of years. Here we use sand flume studies to show that the distinct morphology of martian stepped (terraced) deltas could only have originated from a single basin-filling event on a timescale of tens of years. Stepped deltas therefore provide a minimum and maximum constraint on the duration and magnitude of some surface flows on Mars. We estimate that the amount of water required to fill the basin and deposit the delta is comparable to the amount of water discharged by large terrestrial rivers, such as the Mississippi. The massive discharge, short timescale, and the associated short canyon lengths favour the hypothesis that stepped fans are terraced delta deposits draped over an alluvial fan and formed by water released suddenly from subsurface storage. PMID:18288190

  1. On the precipitation of delta phase in ALLVAC® 718Plus

    NASA Astrophysics Data System (ADS)

    Messé, O. M.; Barnard, J. S.; Pickering, E. J.; Midgley, P. A.; Rae, C. M. F.

    2014-04-01

    ALLVAC 718Plus is a new commercial superalloy derived from Inconel 718, but possessing a higher temperature capability whilst employing the same philosophy regarding the microstructure. Many articles have been published describing various heat treatments exploiting the precipitation of intermetallic phases at grain boundaries to optimize the mechanical properties over a range of testing conditions. The requirement to further improve the mechanical properties of this alloy drives our interest in the precipitation mechanism of the delta and eta phases found in this alloy. We report the presence of finely layered structures composed of two phases, delta and eta, with distinct structures and chemistries. Possible pathways to explain this precipitation in 718Plus are considered as follows: (i) the sequential formation of the delta from eta phase and (ii) the simultaneous precipitation of both eta and delta facilitated via solute rejection. Both can result in the formation of those small delta layers observed in HRSTEM. We discuss which is most likely by comparing the relative alignment of the phases by image processing and the analysis of the HRSTEM images, and propose formation mechanisms consistent with the distinctive dislocation structures observed at the interface.

  2. Transmembrane topography of the nicotinic acetylcholine receptor delta subunit.

    PubMed Central

    McCrea, P D; Popot, J L; Engelman, D M

    1987-01-01

    Current folding models for the nicotinic acetylcholine receptor (AChR) predict either four or five transmembrane segments per subunit. The N-terminus of each subunit is almost certainly extracellular. We have tested folding models by determining biochemically the cellular location of an intermolecular disulfide bridge thought to lie at the delta subunit C-terminus. Dimers of AChR linked through the delta-delta bridge were prepared from Torpedo marmorata and T.californica electric organ. The disulfide's accessibility to hydrophilic reductants was tested in a reconstituted vesicle system. In right-side-out vesicles (greater than 95% ACh binding sites outwards), the bridge was equally accessible whether or not vesicles had been disrupted by freeze--thawing or by detergents. Control experiments based on the rate of reduction of entrapped diphtheria toxin and measurements of radioactive reductant efflux demonstrated that the vesicles provide an adequate permeability barrier. In reconstituted vesicles containing AChR dimers in scrambled orientations, right-side-out dimers were reduced to monomers three times more rapidly than inside-out dimers, consistent with the measured rate of reductant permeation. These observations indicate that in reconstituted vesicles the delta-delta disulfide bridge lies in the same aqueous space as the ACh binding sites. They are most easily reconciled with folding models that propose an even number of transmembrane crossing per subunit. PMID:3428268

  3. STATISTICAL PROPERTIES OF GALACTIC {delta} SCUTI STARS: REVISITED

    SciTech Connect

    Chang, S.-W.; Kim, D.-W.; Byun, Y.-I.; Protopapas, P. E-mail: kim@mpia-hd.mpg.de

    2013-05-15

    We present statistical characteristics of 1578 {delta} Scuti stars including nearby field stars and cluster member stars within the Milky Way. We obtained 46% of these stars (718 stars) from work by Rodriguez and collected the remaining 54% of stars (860 stars) from other literature. We updated the entries with the latest information of sky coordinates, color, rotational velocity, spectral type, period, amplitude, and binarity. The majority of our sample is well characterized in terms of typical period range (0.02-0.25 days), pulsation amplitudes (<0.5 mag), and spectral types (A-F type). Given this list of {delta} Scuti stars, we examined relations between their physical properties (i.e., periods, amplitudes, spectral types, and rotational velocities) for field stars and cluster members, and confirmed that the correlations of properties are not significantly different from those reported in Rodriguez's work. All the {delta} Scuti stars are cross-matched with several X-ray and UV catalogs, resulting in 27 X-ray and 41 UV-only counterparts. These counterparts are interesting targets for further study because of their uniqueness in showing {delta} Scuti-type variability and X-ray/UV emission at the same time. The compiled catalog can be accessed through the Web interface http://stardb.yonsei.ac.kr/DeltaScuti.

  4. Ancient Martian Deltas: Evidence for Shallow and Deep Standing Bodies of Water

    NASA Astrophysics Data System (ADS)

    Jew, C. L.; Kim, W.; Lim, Y.; Piliouras, A.

    2015-12-01

    Ancient deltas on Mars are indicative of a geologic history composed of complex fluvio-deltaic deposits. We focus on two morphologically different deltas preserved on Mars, one located in the Jezero crater and the other in the Shalbatana Valles canyon. The Jezero delta, formed during the Noachian age, is a large fluvial delta with strong channelization and a rigid shoreline resembling a terrestrial delta. In contrast, the Shalbatana Delta is a smaller scaled more briefly lived delta system, developed during the Hesperian, that is characterized by its smooth and simple planform. Evidence from previous studies on these Martian deltas such as the base level, mechanism to build sediment cohesion, estimated discharge, and time of formation offer support to ultimately discover why one delta drastically differs from the other. Based upon the observations from these two locations, we investigate through our physical experiments the conditions required to create these prograding deltas. We use carbonate precipitation in our experiments as a mechanism to increase bank stability, an alternative for any chemically driven precipitated deposits that potentially improve cohesion as vegetation does for terrestrial deltas. We found that there are differences in floodplain thickness, channelization, shoreline rugosity, and delta shape in the carbonate verse non-carbonate runs. Additionally, we conducted runs for isolating the influence that shallow and deep standing bodies of water have on prograding deltas. The experimental results suggested that the highly channelized delta (e.g., Jezero delta) rapidly prograded into a shallow body of water, covering a broader surface area and is dependent on a cohesive force for channel organization. On the contrary, Gilbert-type delta (e.g., Shalbatana delta) was best replicated when prograding into a deep standing body of water. Investigation using the experimental carbonate deltas suggests that cohesion results in better channelization (more

  5. Nile delta: recent geological evolution and human impact.

    PubMed

    Stanley, D J; Warne, A G

    1993-04-30

    Few countries in the world are as dependent on water from a single source as Egypt. The natural Nile cycle of flow and sediment discharge has been disrupted by human intervention, including closure of the High Aswan Dam; this intervention has resulted in a series of responses that now threaten the northern Nile delta. Erosion, salinization, and pollution are inducing a marked decline in agricultural productivity and loss of land and coastal lagoons at a time when the population is expanding exponentially. Geological analyses of radiocarbon-dated cores across the northern delta are used to interpret the interaction of sea-level changes, climatic oscillations, subsidence, and transport processes during the past 35,000 years. Recognition of long-term trends of these natural factors provides a basis to evaluate the profound impact of human activity and to assess future changes in the Nile delta ecosystem. PMID:17812219

  6. Morphology of river deltas on Titan and Earth

    NASA Astrophysics Data System (ADS)

    Witek, Piotr; Czechowski, Leszek

    2016-07-01

    The Cassini-Huygens mission is entering its final phase. The landing of Huygens on Titan and flybys performed by the Cassini probe during the last ten years revolutionized our knowledge about that moon, revealing a complex fluvio-lacustrine environment. Despite significant differences in composition, temperature and gravity, the processes of sediment transport and deposition are similar on Earth and Titan. We performed numerical simulations of development of river deltas in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. We found that evolution of deltaic deposits is more rapid on Titan due to higher efficiency of transport, but the flat, lobate river deltas may form in narrower range of parameters than on Earth. Our results help in understanding the evolution of sedimentary deposits and may partially explain the paucity of river deltas in Titan's lakes.

  7. Mekong Delta at the crossroads: more control or adaptation?

    PubMed

    Käkönen, Mira

    2008-05-01

    Development in the Mekong Delta of Vietnam has been very dynamic in the recent past, and currently it stands at an interesting crossroads. On one hand, agricultural production has developed successfully, and economic growth has been very rapid, but on the other hand, intensifying agriculture and large-scale water-control structures have challenged the environmental sustainability and social equity. The development plans have included a strong belief in the human mastery over the nature and waters of the Mekong Delta. In many cases, water resources planners have underestimated the complexity and integrated nature of the ecology and livelihoods of the Mekong Delta. This article examines cases where development efforts, while successful in some dimensions, have also contributed to create new risks for, especially, the poorest groups. The current situation calls for a more sustainable future route that would require examination of more adaptive measures in relation to the changing water flows of the Mekong River. PMID:18595276

  8. Hepatitis delta virus: A fascinating and neglected pathogen

    PubMed Central

    Cunha, Celso; Tavanez, João Paulo; Gudima, Severin

    2015-01-01

    Hepatitis delta virus (HDV) is the etiologic agent of the most severe form of virus hepatitis in humans. Sharing some structural and functional properties with plant viroids, the HDV RNA contains a single open reading frame coding for the only virus protein, the Delta antigen. A number of unique features, including ribozyme activity, RNA editing, rolling-circle RNA replication, and redirection for a RNA template of host DNA-dependent RNA polymerase II, make this small pathogen an excellent model to study virus-cell interactions and RNA biology. Treatment options for chronic hepatitis Delta are scarce and ineffective. The disease burden is perhaps largely underestimated making the search for new, specific drugs, targets, and treatment strategies an important public health challenge. In this review we address the main features of virus structure, replication, and interaction with the host. Virus pathogenicity and current treatment options are discussed in the light of recent developments. PMID:26568914

  9. Hepatitis delta virus: A fascinating and neglected pathogen.

    PubMed

    Cunha, Celso; Tavanez, João Paulo; Gudima, Severin

    2015-11-12

    Hepatitis delta virus (HDV) is the etiologic agent of the most severe form of virus hepatitis in humans. Sharing some structural and functional properties with plant viroids, the HDV RNA contains a single open reading frame coding for the only virus protein, the Delta antigen. A number of unique features, including ribozyme activity, RNA editing, rolling-circle RNA replication, and redirection for a RNA template of host DNA-dependent RNA polymerase II, make this small pathogen an excellent model to study virus-cell interactions and RNA biology. Treatment options for chronic hepatitis Delta are scarce and ineffective. The disease burden is perhaps largely underestimated making the search for new, specific drugs, targets, and treatment strategies an important public health challenge. In this review we address the main features of virus structure, replication, and interaction with the host. Virus pathogenicity and current treatment options are discussed in the light of recent developments. PMID:26568914

  10. Dynamical instabilities of warm npe matter: {delta} meson effects

    SciTech Connect

    Pais, Helena; Santos, Alexandre; Providencia, Constanca

    2009-10-15

    The effects of {delta} mesons on the dynamical instabilities of cold and warm nuclear and stellar matter at subsaturation densities are studied in the framework of relativistic mean-field hadron models (NL3, NL{rho}, and NL{rho}{delta}) with the inclusion of the electromagnetic field. The distillation effect and the spinodals for all the models considered are discussed. The crust-core transition density and pressure are obtained as a function of temperature for {beta}-equilibrium matter with and without neutrino trapping. An estimation of the size of the clusters formed in the nonhomogeneous phase and the corresponding growth rates are made. It is shown that cluster sizes increase with temperature. The effects of the {delta} meson on the instability region are larger for low temperatures, very asymmetric matter, and densities close to the spinodal surface. It increases the distillation effect above {approx}0.4{rho}{sub 0} and has the opposite effect below that density.

  11. Pen Branch stream corridor and Delta Wetlands change assessment

    SciTech Connect

    Blohm, J.D.

    1995-06-01

    Airborne multispectral scanner data from 1987 to 1991 covering the Pen Branch corridor and delta at SRS were utilized to provide a detailed change detection analysis. The multispectral data were geo-referenced to a Universal Transverse Mercator projection using finite element registration. Each year was then classified into eleven different landcover categories, and the yearly changes in each landcover category were analyzed. The decrease in operations of K Reactor in 1988 has resulted in drying of the corridor and delta. This has led to the decline of nonpersistent vegetation and the increase of persistent vegetation. Cattails, willow, and bottomland hardwoods, in particular, have grown to dominate the corridor and most of the delta.

  12. Monitoring the urbanization of the Nile Delta, Egypt.

    SciTech Connect

    Sultan, M.; Fiske, M.; Stein, T.; Gamal, M.; El Araby, H.; Madani, A.; Mehanee, S.; Becker, R.; Environmental Research; Washington Univ.; Cairo Univ. Center for Environmental Hazard Mitigation

    1999-11-01

    Comparisons of satellite images of the Nile Delta, acquired in 1972, 1984 and 1990, indicate that urban growth is endangering Egypt's agricultural productivity. Urban areas occupied a minimum of 3.6%, 4.7% and 5.7% of the Delta in 1972, 1984 and 1990, respectively, an increase of 58% in 18 years. Approximately half of this increase occurred between 1984 and 1990. If this trend continues, Egypt could lose 12% of its total agricultural area to urbanization by 2010. Despite the fact that growth is pronounced around the cities, it is the growth around the thousands of small villages that poses the largest threat to the agricultural productivity of the Nile Delta. The cumulative growth rate for the cities and large villages between 1972 and 1990 is 37%, and that for the small villages is 77% for the same time period.

  13. The Delta IV launch table begins transfer to CCAFS

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A launch table, fabricated by Jered Industries in Georgia for Boeing, moves away from the turn basin and the barge that brought it to the turn basin in KSC's Launch Complex 39 Area. In the background is the Vehicle Assembly Building. The table was built in support of the Delta Evolved Expendable Launch Vehicle (EELV) program, known as Delta IV. It was floated on the barge down the Intercoastal Waterway, through the Barge Canal to the turn basin. The table is approximately 70 feet long, 40 feet wide and 50 feet high, and weighs about 600,000 pounds. It is being transferred to Launch Complex 37B, Cape Canaveral Air Force Station, the Delta IV launch site. Accompanying the launch table on the barge are flame deflectors, which are also to be erected on pad 37B.

  14. The Delta IV launch table is transferred to CCAFS

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Looking somewhat like a medieval building, this launch table was built in support of the Delta Evolved Expendable Launch Vehicle (EELV) program, known as Delta IV. Fabricated by Jered Industries in Georgia, it was floated on a barge down the Intercoastal Waterway, through the Barge Canal to the turn basin in the Launch Complex 39 Area. In the background is the Vehicle Assembly Building. The table is approximately 70 feet long, 40 feet wide and 50 feet high, and weighs about 600,000 pounds. It is being transferred to Launch Complex 37B, Cape Canaveral Air Force Station, the site of the Delta IV launch complex under construction. Accompanying the launch table on the barge are flame deflectors, which are also to be erected on pad 37B.

  15. Theory for the curvature dependence of delta front progradation

    NASA Astrophysics Data System (ADS)

    Ke, Wun-Tao; Capart, Hervé

    2015-12-01

    When Gilbert-type deltas respond to uneven sediment supply or advance over irregular basin bathymetry, they develop curved, creased fronts prograding at speeds that vary with location along the shoreline. Relations governing the progradation rate, however, have so far been proposed only for simple special cases. In this paper, we exploit the special properties of solutions to the eikonal equation to derive a general progradation relation, applicable to delta fronts of finite angle of repose and arbitrary shoreline planform. In these circumstances, the theory explicitly relates the progradation rate to the local shoreline curvature. We illustrate the resulting morphodynamics with numerical and analytical solutions for a sinuous delta front. The proposed relation can be used to model deltaic evolution or deduce spanwise distributions of sediment supply rates from observations of foreset evolution.

  16. delta. sigma/sub L//(pp) and jet physics

    SciTech Connect

    Richards, D.G.

    1988-01-01

    We show that there is a positive contribution to ..delta..sigma/sub L/(pp; s) = sigma /sub tot/(p(+)p(+); s) /minus/ sigma/sub tot/(p(+)p(/minus/); s) (where the +- refer to proton helicities) associated with the pointlike scattering of fundamental constituents. Simple arguments imply that this positive contribution would, at very high s, be larger in absolute value than the negative contribution to ..delta..sigma/sub L/ predicted from the exchange of the A/sub 1/ reggeon, and furthermore may provide important insight into the shape of the spin weighted quark and gluon distributions. Measurements of ..delta..sigma/sub L/ in the energy range ..sqrt..s = 18 /minus/ 30 GeV also should help clarify theoretical ideas associated with the observations of ''minijets'' and could aid in the prediction of event structure at future high energy colliders. 24 refs. 6 figs.

  17. Delta K measurements with synthetic aperture radar data. [micirowavelength difference values

    NASA Technical Reports Server (NTRS)

    Larson, R. W.; Jackson, P. L.; Klooster, A.

    1985-01-01

    Delta K measurements are obtained from the interference of two electromagnetic waves of different frequencies. Constructive interference occurs when 2pi phase differences between the two frequencies correspond to a surface wavelength. Previous Delta K measurements have used two discrete frequencies for this purpose. Range pulses and Doppler signatures of a synthetic aperture radar system were filtered to obtain a sequence of Delta K values. Those Delta K values which correspond to the wavelengths of known surfaces show maximum constructive interference. SAR data can therefore be used for Delta K measurements, indicating the possibility of selective Delta K filtering during data gathering.

  18. Mississippi Delta, Radar Image with Colored Height

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for the animation

    About the animation: This simulated view of the potential effects of storm surge flooding on Lake Pontchartrain and the New Orleans area was generated with data from the Shuttle Radar Topography Mission. Although it is protected by levees and sea walls against storm surges of 18 to 20 feet, much of the city is below sea level, and flooding due to storm surges caused by major hurricanes is a concern. The animation shows regions that, if unprotected, would be inundated with water. The animation depicts flooding in one-meter increments.

    About the image: The geography of the New Orleans and Mississippi delta region is well shown in this radar image from the Shuttle Radar Topography Mission. In this image, bright areas show regions of high radar reflectivity, such as from urban areas, and elevations have been coded in color using height data also from the mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

    New Orleans is situated along the southern shore of Lake Pontchartrain, the large, roughly circular lake near the center of the image. The line spanning the lake is the Lake Pontchartrain Causeway, the world's longest over water highway bridge. Major portions of the city of New Orleans are below sea level, and although it is protected by levees and sea walls, flooding during storm surges associated with major hurricanes is a significant concern.

    Data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data

  19. Stable isotope deltas: tiny, yet robust signatures in nature.

    PubMed

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

  20. Salinity Impacts on Agriculture and Groundwater in Delta Regions

    NASA Astrophysics Data System (ADS)

    Clarke, D.; Salehin, M.; Jairuddin, M.; Saleh, A. F. M.; Rahman, M. M.; Parks, K. E.; Haque, M. A.; Lázár, A. N.; Payo, A.

    2015-12-01

    Delta regions are attractive for high intensity agriculture due to the availability of rich sedimentary soils and of fresh water. Many of the world's tropical deltas support high population densities which are reliant on irrigated agriculture. However environmental changes such as sea level rise, tidal inundation and reduced river flows have reduced the quantity and quality of water available for successful agriculture. Additionally, anthropogenic influences such as the over abstraction of ground water and the increased use of low quality water from river inlets has resulted in the accumulation of salts in the soils which diminishes crop productivity. Communities based in these regions are usually reliant on the same water for drinking and cooking because surface water is frequently contaminated by commercial and urban pollution. The expansion of shallow tube well systems for drinking water and agricultural use over the last few decades has resulted in mobilisation of salinity in the coastal and estuarine fringes. Sustainable development in delta regions is becoming constrained by water salinity. However salinity is often studied as an independent issue by specialists working in the fields of agriculture, community water supply and groundwater. The lack of interaction between these disciplines often results in corrective actions being applied to one sector without fully assessing the effects of these actions on other sectors. This paper describes a framework for indentifying the causes and impacts of salinity in delta regions based on the source-pathway-receptor framework. It uses examples and scenarios from the Ganges-Brahmaputra-Meghna delta in Bangladesh together with field measurements and observations made in vulnerable coastal communities. The paper demonstrates the importance of creating an holistic understanding of the development and management of water resources to reduce the impact of salinity in fresh water in delta regions.

  1. Stable isotope deltas: Tiny, yet robust signatures in nature

    USGS Publications Warehouse

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

  2. The sequence stratigraphy of Upper Carboniferous deltas, western Ireland

    SciTech Connect

    Elliott, T. ); Pulham, A. )

    1991-03-01

    Upper Carboniferous deltaic cyclothems across northern Europe are defined by distinctive faunal concentrate horizons termed 'marine bands' that represent widespread transgressions. Cyclothems in the Namurian Clare basin are approximately 200 m in thickness and comprise an initial thick (up to 150 m) progradational deep-water delta front overlain by smaller scale (5-10 m) bay fills and thick (30-70 m), composite fluvial channels, capped by small to moderate scale (5-35 m) shoreline and/or shallow-water delta fronts. Sand bodies in the delta fronts include isolate, 2-3 km wide mouth-bars, implying that distributary channels were narrow and widely spaced. This contradicts the evidence of the fluvial channel complexes, which are widespread, multilateral bodies up to 25 km wide. In view of these contrasts, the fluvial channels are interpreted as incised valley fills resulting from a relative fall in sea level. The bases of these complexes are interpreted as sequence boundaries; the fluvial channels as lowstand wedges; the overlying shorelines and shallow-water deltas as transgressive systems tracts; and the marine bands as maximum flooding surfaces. Subdivision of the thicker delta fronts into highstand and lowstand components can be made in several ways. Interpretations are dependent on the significance attached to various facies surfaces in these deep-water, possibly shelf-edge delta fronts. The recognition of lowstand, Type 1 sequence boundaries extends the traditional view of the cyclothems as being defined by Frazier-Galloway type flooding surfaces and argues that erosional phases, nondepositional interfluves, and lowstand deep basin deposits should be sought throughout these Upper Carboniferous successions.

  3. Estimating Natural Flows into the California's Sacramento - San Joaquin Delta

    NASA Astrophysics Data System (ADS)

    Huang, G.; Kadir, T.; Chung, F. I.

    2014-12-01

    Natural flows into the California's Sacramento - San Joaquin Delta under predevelopment vegetative conditions, if and when reconstructed, can serve as a useful guide to establish minimum stream flows, restoration targets, and a basis for assessing impacts of global warming in the Bay-Delta System. Daily simulations of natural Delta flows for the period 1922-2009 were obtained using precipitation-snowmelt-runoff models for the upper watersheds that are tributaries to the California's Central Valley, and then routing the water through the Central Valley floor area using a modified version of the California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM) for water years 1922 through 2009. Daily stream inflows from all major upper watersheds were simulated using 23 Soil Water Assessment Tool (SWAT) models. Historical precipitation and reference evapotranspiration data were extracted from the SIMETAW2 with the 4km gridded meteorological data. The Historical natural and riparian vegetation distributions were compiled from several pre-1900 historical vegetation maps of the Central Valley. Wetlands were dynamically simulated using interconnected lakes. Flows overtopping natural levees were simulated using flow rating curves. New estimates of potential evapotranspiration from different vegetative classes under natural conditions were also used. Sensitivity simulations demonstrate that evapotranspiration estimates, native vegetation distribution, surface-groundwater interaction parameters, extinction depth for groundwater uptake, and other physical processes play a key role in the magnitude and timing of upstream flows arriving at the Delta. Findings contradict a common misconception that the magnitude of inflows to the Delta under natural vegetative conditions is greater than those under the historical agricultural and urban land use development. The developed models also enable to study the impacts of global warming by modifying meteorological and

  4. On the meaning of [Delta]T/T

    SciTech Connect

    Stebbins, A.

    1993-02-01

    One of the most interesting aspects of the discovery of Microwave Background Radiation (MBR) anisotropy by the COBE satellite is the ability to compare these anisotropies with the amplitude of density inhomogeneities we measure. Combining these two, we can get a unified'' view of the inhomogeneities present in our universe on a broad range of scales. To make this comparison we must be able to translate [Delta]T/T into [delta]p/[bar p], the mass overdensity. This latter quantity we may try to determine from the distribution of galaxies and their velocities.

  5. 65 Degree Delta Wing in the LTPT-Test 360

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This 65-degree delta wing model test is part of an experimental and computational effort aimed at isolating the effects of Reynolds number, Mach number, and leading-edge radius on partial leading-edge vortex separation. Surface pressure measurments were taken in the Low-Turbulence Pressure Tunnel (LTPT) for a Reynolds number range from 1.5 to 12 Million over an angle of attack range from -2 to 30 degrees at Mach numbers of 0.2 and 0.4. This model is a 3/4-scale version of another 65-degree delta wing tested to full-scale Reynolds numbers in the National Transonic Facility.

  6. Holocene highstand shoreline of the Chao Phraya delta, Thailand

    NASA Astrophysics Data System (ADS)

    Somboon, J. R. P.; Thiramongkol, N.

    The Holocene highstand shoreline of the Chao Phraya delta is deciphered using the combined techniques of geomophology, palynology, stratigraphy, and C-14 dating of the basal peat. The results of such studies have indicated that at the height of Holocene transgression the sea covered most of the present Chao Phraya delta to as far as north of Ayuthaya city around 6500-7300 yr B.P. The paleoenvironment of the low-lying areas of Holocene sea was generally similar to that of the modern tidal-deltaic environments.

  7. The Delta IV launch table waits for transfer to CCAFS

    NASA Technical Reports Server (NTRS)

    2000-01-01

    In the turn basin near the Vehicle Assembly Building (left) a launch table is docked, waiting for transfer to Launch Complex 37B, Cape Canaveral Air Force Station. The table was fabricated by Jered Industries in Georgia in support of the Delta Evolved Expendable Launch Vehicle (EELV) program, known as Delta IV. It was floated on a barge down the Intercoastal Waterway, through the Barge Canal to the turn basin. The table is approximately 70 feet long, 40 feet wide and 50 feet high, and weighs about 600,000 pounds. Accompanying the launch table on the barge are flame deflectors, which are also to be erected on pad 37B.

  8. Mesospheric ionization and O2 1Delta(g) depletion

    NASA Technical Reports Server (NTRS)

    Spear, K. A.; Solomon, S.

    1987-01-01

    Observations of O2 1Delta(g) emission during solar proton events reveal large depletions below 80 and near 90 km. The lower-altitude depletions are believed to be due to odd hydrogen production and associated depletion of ozone, but the mechanism producing the depletion near 90 km has not yet been established. In this paper, it is proposed that an exothermic charge exchange reaction between O2(+) and O2 1Delta(g) is likely to be responsible for these high-altitude depletions. In particular, it is shown that the vertical structure of the observed change in airglow emission is consistent with this mechanism.

  9. Delta-baryon mass in a covariant Faddeev approach

    SciTech Connect

    Nicmorus, D.; Eichmann, G.; Krassnigg, A.; Alkofer, R.

    2009-09-01

    We present a calculation of the three-quark core contribution to the mass of the {delta} resonance in a Poincare-covariant Faddeev framework. A consistent setup for the dressed-quark propagator, the quark-quark and quark-'diquark' interactions is used, where all the ingredients are solutions of their respective Dyson-Schwinger or Bethe-Salpeter equations in rainbow-ladder truncation. We discuss the evolution of the {delta} mass with the current-quark mass and compare to the previously obtained mass of the nucleon.

  10. Transmission of the hepatitis B virus-associated delta agent to the eastern woodchuck.

    PubMed Central

    Ponzetto, A; Cote, P J; Popper, H; Hoyer, B H; London, W T; Ford, E C; Bonino, F; Purcell, R H; Gerin, J L

    1984-01-01

    delta agent of human origin was inoculated into four woodchucks chronically infected with woodchuck hepatitis virus (WHV). The animals developed delta infections with serologic patterns similar to those previously observed in human and chimpanzee infections. delta antigen was detected transiently in serum and liver and was followed by seroconversion to anti-delta antibody. Analogous to the chimpanzee model of delta infection, serum and hepatocyte markers of WHV were suppressed in the woodchuck during acute delta infection. The suppression of WHV DNA in serum was evident only during the time of delta-antigen positivity, while the inhibition of other WHV markers was more protracted. The delta antigen in woodchuck sera circulated as an internal component of a particle similar in size to the human delta particle (36-nm diameter) and was encapsidated by the woodchuck hepatitis virus surface antigen; delta antigen from infected woodchuck and chimpanzee livers had similar biophysical properties. Histologic analysis showed that experimental delta infection is associated with a transient acute hepatitis in woodchucks and loss of hepatocytes carrying WHV antigens. The lesions differed from the conspicuous hepatitis associated with reappearance of WHV replication. Hepatitis B-like viruses, therefore, appear to provide the requisite helper functions for delta replication and the woodchuck represents a useful model for study of the virology and pathology of the delta agent. Images PMID:6585793

  11. Identification of E2F1 as a positive transcriptional regulator for {delta}-catenin

    SciTech Connect

    Kim, Kwonseop; Oh, Minsoo; Ki, Hyunkyoung; Wang Tao; Bareiss, Sonja; Fini, M. Elizabeth.; Li Dawei; Lu Qun

    2008-05-02

    {delta}-Catenin is upregulated in human carcinomas. However, little is known about the potential transcriptional factors that regulate {delta}-catenin expression in cancer. Using a human {delta}-catenin reporter system, we have screened several nuclear signaling modulators to test whether they can affect {delta}-catenin transcription. Among {beta}-catenin/LEF-1, Notch1, and E2F1, E2F1 dramatically increased {delta}-catenin-luciferase activities while {beta}-catenin/LEF-1 induced only a marginal increase. Rb suppressed the upregulation of {delta}-catenin-luciferase activities induced by E2F1 but did not interact with {delta}-catenin. RT-PCR and Western blot analyses in 4 different prostate cancer cell lines revealed that regulation of {delta}-catenin expression is controlled mainly at the transcriptional level. Interestingly, the effects of E2F1 on {delta}-catenin expression were observed only in human cancer cells expressing abundant endogenous {delta}-catenin. These studies identify E2F1 as a positive transcriptional regulator for {delta}-catenin, but further suggest the presence of strong negative regulator(s) for {delta}-catenin in prostate cancer cells with minimal endogenous {delta}-catenin expression.

  12. Sediment Mixture Controls on Morphodynamics of Experimental Deltas

    NASA Astrophysics Data System (ADS)

    Cheshier, N. R.; van de Lageweg, W. I.; van Dijk, W. M.; Hoyal, D. C.; Kleinhans, M. G.; Postma, G.

    2010-12-01

    The creation of small scale deltas in the laboratory has proven challenging but significant progress has been made in several labs in recent years. Various types of river and fan deltas have been created, ranging from fine- to coarse-grained, non-cohesive to cohesive sediment, and from sheet flow dominated to strongly channelised. These experiments have elucidated a number of important factors and autogenic behaviours under constant boundary conditions, such as channelisation and mouth bar formation and backsedimentation leading to avulsion. However, there has been very little systematic investigation of scale effects (Kleinhans et al., this conference) and of experimental parameter space, particularly the link between the sediment mixture and autogenic delta behaviour. Here we describe systematic pilot experiments designed to investigate the link between sediment mixture properties, such as grain size, sorting, addition of fines or polymers, and delta morphodynamics, described by channel dimensions, network pattern, planform delta shape, and bifurcation mechanisms. These experiments were designed to be small, fast and repeatable, so that large quantities of data can be collected for different mixtures. They are run in conjunction with other small-scale tests on the same sediment mixtures to quantify the link between the mechanical properties of delta substrate, such as bank erodibility, and delta organisation. Discharge and sediment feed rate were kept constant and the same in all experiments. Delta evolution was recorded by high-resolution time-lapse photography, emphasising the channels by coloured flow and showing sorting patterns in cases with sediment mixtures. Topography was measured at sub-mm resolution at a few time steps for each delta. For sediment we used various combinations of well-sorted fine sand or poorly sorted sand with some fine gravel, and silica flour and/or polymer with benthonite. The uniform fine sand invariably exhibited sheet flow or

  13. Integrating Delta Building Physics & Economics: Optimizing the Scale of Engineered Avulsions in the Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Kenney, M. A.; Mohrig, D.; Hobbs, B. F.; Parker, G.

    2011-12-01

    Land loss in the Mississippi River Delta caused by subsidence and erosion has resulted in habitat loss, interference with human activities, and increased exposure of New Orleans and other settled areas to storm surge risks. Prior to dam and levee building and oil and gas production in the 20th century, the long term rates of land building roughly balanced land loss through subsidence. Now, however, sediment is being deposited at dramatically lower rates in shallow areas in and adjacent to the Delta, with much of the remaining sediment borne by the Mississippi being lost to the deep areas of the Gulf of Mexico. A few projects have been built in order to divert sediment from the river to areas where land can be built, and many more are under consideration as part of State of Louisiana and Federal planning processes. Most are small scale, although there have been some proposals for large engineered avulsions that would divert a significant fraction of the remaining available sediment (W. Kim, et al. 2009, EOS). However, there is debate over whether small or large diversions are the economically optimally and socially most acceptable size of such land building projects. From an economic point of view, the optimal size involves tradeoffs between scale economies in civil work construction, the relationship between depth of diversion and sediment concentration in river water, effects on navigation, and possible diminishing returns to land building at a single location as the edge of built land progresses into deeper waters. Because land building efforts could potentially involve billions of dollars of investment, it is important to gain as much benefit as possible from those expenditures. We present the result of a general analysis of scale economies in land building from engineered avulsions. The analysis addresses the question: how many projects of what size should be built at what time in order to maximize the amount of land built by a particular time? The analysis

  14. Investigations into the \\delta 15N and \\delta 13C of POM, Primary Producers, and Filter Feeders in the Florida Keys Coral Reef Tract

    NASA Astrophysics Data System (ADS)

    Lamb, K. A.; Swart, P. K.

    2004-12-01

    In order to examine the possible influences of anthropogenic wastes on the Florida Keys coral reef tract, water column particulate organic matter \\(POM\\), primary producers, and filter feeders were sampled from within the coastal waters of the reef tract, and analyzed for \\delta 15N and \\delta 13C isotopic composition. The POM was found to have a mean \\delta 15N value of +4.13\\permil (\\pm 1.03\\permil\\) and a mean \\delta 13C value of -19.93\\permil (\\pm 0.58\\permil). The \\delta 13C values for POM across the entire reef tract were heavier inshore \\(avg \\delta 13C = -18.29\\permil \\(\\pm 1.04\\permil\\)\\) and became lighter offshore \\(avg \\delta 13C = -21.41\\permil \\(\\pm 0.89\\permil\\)\\), which is consistent with influences from benthic algae/seagrass closer to shore in contrast to open-marine influences offshore. The \\delta 15N values for POM were neither temporally nor spatially interrelated, as the data showed no clear trend moving in either the inshore or offshore direction. Instead, our \\delta 15N values for POM reflect a combined influence from nitrogen fixation \\(\\approx0\\permil\\), zooplankton and other suspended particles, and not anthropogenic wastes \\(>+10\\permil\\), as other authors claim. The mean isotopic composition of various primary producers suggests a nitrogen fixation source of nutrients to the reef system (Halimeda sp. (\\delta 15N = 2.43\\permil; \\delta 13C = -18.04\\permill), Dictyota sp. (\\delta 15N = +2.86\\permil; \\delta 13C = -16.30\\permil), Thalassia sp. (\\delta 15N = 2.39\\permil; \\delta 13C = -10.32\\permil)), while filter feeders were found to have a mean isotopic composition more similar to POM values (sponge \\delta 15N = 4.95\\permil; \\delta 13C = -18.02\\permil). Our data simply do not appear to show evidence of anthropogenic influence on the Florida Keys reef tract. Further more, we suggest that \\delta 15N values of +4\\permil, which have recently been suggested to indicate anthropogenic

  15. Unraveling the Effect of Thermomechanical Treatment on the Dissolution of Delta Ferrite in Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Rezayat, Mohammad; Mirzadeh, Hamed; Namdar, Masih; Parsa, Mohammad Habibi

    2016-02-01

    Considering the detrimental effects of delta ferrite stringers in austenitic stainless steels and the industrial considerations regarding energy consumption, investigating, and optimizing the kinetics of delta ferrite removal is of vital importance. In the current study, a model alloy prone to the formation of austenite/delta ferrite dual phase microstructure was subjected to thermomechanical treatment using the wedge rolling test aiming to dissolve delta ferrite. The effect of introducing lattice defects and occurrence of dynamic recrystallization (DRX) were investigated. It was revealed that pipe diffusion is responsible for delta ferrite removal during thermomechanical process, whereas when the DRX is dominant, the kinetics of delta ferrite dissolution tends toward that of the static homogenization treatment for delta ferrite removal that is based on the lattice diffusion of Cr and Ni in austenite. It was concluded that the optimum condition for dissolution of delta ferrite can be defined by the highest rolling temperature and strain in which DRX is not pronounced.

  16. 75 FR 20598 - Public Buildings Service; Prospect Island, Sacramento Delta, Solano County, CA; Transfer of Property

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... From the Federal Register Online via the Government Publishing Office GENERAL SERVICES ADMINISTRATION Public Buildings Service; Prospect Island, Sacramento Delta, Solano County, CA; Transfer of... identified as Prospect Island, Sacramento Delta, Solano County, California to the State of...

  17. 78 FR 71634 - 60-Day Notice of Proposed Information Collection: Delta Community Capital Initiative Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT 60-Day Notice of Proposed Information Collection: Delta Community Capital Initiative... Collection Title of Information Collection: Delta Community Capital Initiative. OMB Approval Number:...

  18. 76 FR 62055 - Mississippi Delta Energy Agency, Clarksdale Public Utilities Commission, Public Service...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-06

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Mississippi Delta Energy Agency, Clarksdale Public Utilities Commission... Practice and Procedures, and the applicable Tariff on file with the Commission, Mississippi Delta...

  19. A bifunctional Delta12,Delta15-desaturase from Acanthamoeba castellanii directs the synthesis of highly unusual n-1 series unsaturated fatty acids.

    PubMed

    Sayanova, Olga; Haslam, Richard; Guschina, Irina; Lloyd, David; Christie, William W; Harwood, John L; Napier, Johnathan A

    2006-12-01

    The free-living soil protozoon Acanthamoeba castellanii synthesizes a range of polyunsaturated fatty acids, the balance of which can be altered by environmental changes. We have isolated and functionally characterized in yeast a microsomal desaturase from A. castellanii, which catalyzes the sequential conversion of C(16) and C(18) Delta9-monounsaturated fatty acids to di- and tri-unsaturated forms. In the case of C(16) substrates, this bifunctional A. castellanii Delta12,Delta15-desaturase generated a highly unusual fatty acid, hexadecatrienoic acid (16:3Delta(9,12,15)(n-1)). The identification of a desaturase, which can catalyze the insertion of a double bond between the terminal two carbons of a fatty acid represents a new addition to desaturase functionality and plasticity. We have also co-expressed in yeast the A. castellanii bifunctional Delta12,Delta15-desaturase with a microsomal Delta6-desaturase, resulting in the synthesis of the highly unsaturated C(16) fatty acid hexadecatetraenoic acid (16:4Delta(6,9,12,15)(n-1)), previously only reported in marine microorganisms. Our work therefore demonstrates the feasibility of the heterologous synthesis of polyunsaturated fatty acids of the n-1 series. The presence of a bifunctional Delta12,Delta15-desaturase in A. castellanii is also considered with reference to the evolution of desaturases and the lineage of this protist. PMID:16950768

  20. Evolution of an Anthropocene Delta: Understanding the Interplay of Natural and Anthropogenic Forces That Shaped the Brazos River Subaqueous Delta, USA

    NASA Astrophysics Data System (ADS)

    Carlin, J. A.; Dellapenna, T. M.

    2014-12-01

    Deltas are unique environments that are rich in natural resources and human populations. As a result, human activities directly to the delta and indirectly to the watershed in the Anthropocene have led to changes within the deltaic system as a response to these natural and anthropogenic forces. Understanding the response of deltas to these new forcings will be critical to assess the vulnerability of deltas to global climate change and expanding human populations. The Brazos River Delta, located in the northwestern Gulf of Mexico, served as an ideal study area to investigate the effect of human activities on a delta. Historical alterations to the system include agricultural activity, jetty construction, an engineered mouth diversion, and reservoir construction throughout the early and mid 20th Century. Three subaerial deltaic growth phases were identified based on historic shoreline configurations, and combined with high-resolution geophysical data (swath bathymetry, side scan sonar, CHIRP subbottom profiling) from the subaqueous delta to investigate the subaqueous delta changes over time. Evidence from these alternating progradational and retrogradational periods are preserved within the subaqueous delta. The data showed that as the growth of the subaerial delta changed over time, the subaqueous clinoform was subjected to regions of progradation or abandonment. The abandoned clinoform sections were characterized by a thinning modern clinoform sequence downslope from an erosional scarp. High side scan sonar backscatter features are believed to distinguish exposed erosional surfaces throughout the subaqueous delta demarcating the abandoned sections at the seabed. Prograding clinoform areas lack these high backscatter features. In these areas the modern clinoform was relatively thicker and does not exhibit the upslope erosional scarps. This noticeable asymmetry across the subaqueous delta shows that the Brazos Delta has migrated southwestward resulting from shifts in

  1. Changes in the areal extents of the Athabasca River, Birch River, and Cree Creek Deltas, 1950-2014, Peace-Athabasca Delta, Canada

    NASA Astrophysics Data System (ADS)

    Timoney, Kevin; Lee, Peter

    2016-04-01

    Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.

  2. Geohydrology of the Delta-Clearwater area, Alaska

    USGS Publications Warehouse

    Wilcox, Dorothy E.

    1980-01-01

    The alluvial aquifer in the Delta-Clearwater area, Alaska, is composed of lenticular, interbedded deposits of silt, sand, and gravel. Ground water occurs under both confined and unconfined conditions in the area. The potentiometric surface slopes approximately northward at gradients ranging from about 1 to 25 feet per mile. The aquifer is recharge by seepage through the streambeds of rivers and creeks and by infiltration of precipitation. Water is discharged from the aquifer into the Clearwater Creek network and Clearwater Lake, which are almost entirely spring-fed, at the mouth of the Delta River, and into the Tanana River along the northern boundary of the study area. Year-round ground-water discharge from the aquifer is estimated to exceed 1,200 cubic feet per second. The following ground-water flow system is hypothesized: Channel losses from the Gerstle River, several small creeks draining the Alaska Range, and the Tanana River to the east of Clearwater Creek recharge the sections of the aquifer discharging at the Clearwater Creek network. Channel losses from the Delta River and Jarvis Creek are the main source of recharge to the sections of the aquifer discharging in the vicinity of Clearwater Lake and Big Delta. Additional work is needed to verify these hypotheses. (USGS)

  3. Martensitic nature of {delta} {yields} {gamma} allotropic transformation in plutonium

    SciTech Connect

    Lopez, P.C.; Cost, J.R.; Axler, K.M.

    1996-09-01

    Isothermal and isoplethal studies using differential scanning calorimetry have been conducted to characterize the allotropic transformations of plutonium. The {delta}-{gamma} transformation (upon cooling) was observed to have a classic martensitic nature. The work described herein is the first quantitative study of this phenomena in plutonium.

  4. Validity and reliability of the Delta Healthy Eating Attitudes Scale

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate psychometric properties of an instrument developed to measure psychosocial factors related to the Dietary Guidelines for Americans for a nutrition intervention in the Lower Mississippi Delta (LMD). Social Cognitive Theory constructs social support (SS), s...

  5. Final Narrative Report on Nursing Ethics at Delta College.

    ERIC Educational Resources Information Center

    Pfeiffer, Raymond S.

    This four-part report describes a project undertaken by Delta College to implement two required bioethics courses for nursing students: an introductory course in ethical theories and an advanced course in applications of these theories in nursing. After Part I relates how funding for the project was secured and used, Part II delineates the…

  6. Lee side flow for slender delta wings of finite thickness

    NASA Technical Reports Server (NTRS)

    Szodruch, J. G.

    1980-01-01

    An experimental and theoretical investigation carried out to determine the lee side flow field over delta wings at supersonic speeds is presented. A theoretical method to described the flow field is described, where boundary conditions as a result of the experimental study are needed. The computed flow field with shock induced separation is satisfactory.

  7. Delta FUSE Fairing Installation at Launch Complex 17A

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This NASA Kennedy Space Center (KSC) video release presents footage of the June 19, 1999 installation of the fairing around the Far Ultraviolet Spectroscopic Explorer (FUSE) spacecraft. The spacecraft was previously mated to the Boeing Delta II rocket. Installation took place on Pad A of Launch Complex 17.

  8. 75 FR 56094 - Delta-Mendota Canal Intertie Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ... Area Power Administration Delta-Mendota Canal Intertie Project AGENCY: Western Area Power... fiber optic cable for delivery of project use power as part of the Department of the Interior, Bureau of... (Intertie) project. The Intertie, including the interconnection to Western's system and transmission...

  9. Quadrupolar, Triple [Delta]-Function Potential in One Dimension

    ERIC Educational Resources Information Center

    Patil, S. H.

    2009-01-01

    The energy and parity eigenstates for quadrupolar, triple [delta]-function potential are analysed. Using the analytical solutions in specific domains, simple expressions are obtained for even- and odd-parity bound-state energies. The Heisenberg uncertainty product is observed to have a minimum for a specific strength of the potential. The…

  10. Communication performance of the Intel Touchstone DELTA mesh

    SciTech Connect

    Dunigan, T.H.

    1992-01-01

    The communication performance of the i860-based Intel DELTA mesh supercomputer is compared with the Intel iPSC/860 hypercube and the Ncube 6400 hypercube. Single and multiple hop communication bandwidth and latencies are measured. Concurrent communication speeds and speed under network load are also measured. File I/O performance of the mesh-attached Concurrent File System is measured.

  11. Recent measurement of {delta}G/G at COMPASS

    SciTech Connect

    Bernet, C

    2005-10-06

    We present a preliminary measurement of the gluon polarization {delta}G/G in the nucleon, based on the spin asymmetry of quasi-real photoproduction events for which a pair of large transverse momentum hadrons is produced. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a large polarized 6LiD target. The preliminary helicity asymmetry for the selected events is A{sub paralle}Ll /D = 0.002 {+-} 0.019(stat.) {+-} 0.003(exp.syst.). From this value, a leading order analysis based on the model of PYTHIA leads to the gluon polarization in the nucleon {delta}G/G(xg = 0.095, {mu}2 = 3 GeV2) = 0.024 {+-} 0.089(stat.) {+-} 0.057(syst.). This value is consistent with parameterizations obtained from QCD fits to the g1 data, with a first moment {delta}G {identical_to} {integral}{sub 0}{sup 1} {delta}G(x)dx {approx_equal} 0.5, at the same scale.

  12. {delta}-kick cooling using the Ioffe-Pritchard potential

    SciTech Connect

    Aoki, T.; Kato, T.; Tanami, Y.; Nakamatsu, H.

    2006-06-15

    We demonstrated {delta}-kick cooling of sodium atoms with a three-dimensional anisotropic harmonic potential. The radius and temperature of the atomic cloud oscillated with kick time, indicating that the elongated atomic distribution in phase space rotates in the Ioffe-Pritchard potential. The temperature of kicked atoms was reduced to below the recoil temperature.

  13. Flutter analysis of highly swept delta wings by conventional methods

    NASA Technical Reports Server (NTRS)

    Gibbons, M. D.; Soistmann, D. L.; Bennett, R. M.

    1988-01-01

    The flutter boundaries of six thin highly-swept delta-platform wings have been calculated. Comparisons are made between experimental data and results using several aerodynamic methods. The aerodynamic methods used include a subsonic and supersonic kernel function, second order piston theory, and a transonic small disturbance code. The dynamic equations of motion are solved using analytically calculated mode shapes and frequencies.

  14. Self-reported health of residents of the Mississippi Delta.

    PubMed

    2004-11-01

    The rural Lower Mississippi Delta of Arkansas, Louisiana, and Mississippi has a large economically and socially disadvantaged population at high risk for health problems. Their health status is poorly understood as they are not well represented in national health surveys. A random-digit-dialing telephone survey was conducted in 2000, with 2,236 respondents representing residents of 36 counties along the Mississippi River. Self-reported chronic conditions, health status, and obesity (derived from weight and height) were compared with the nationally representative Continuing Survey of Food Intake of Individuals. High cholesterol, diabetes, and hypertension were significantly higher than in the national sample. Obesity was strikingly higher in Delta children (27.9% versus 16.2%) of all ages and in Delta adults (33.9% versus 17.3%). Controlling for age, income, and gender, African Americans were at particular risk for obesity, hypertension, and diabetes. A public health crisis appears to exist in the Delta given the high prevalence health problems. PMID:15531821

  15. Delta XTE Spacecraft Arrives at CCAS Skid Strip

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Footage shows the U.S Air Force Aircraft "Air Mobility Command" approaching, and landing at the Cape Canaveral Air Station Skid Strip (CCAS). The truck carrying the Delta XTE Spacecraft is also shown as it leaves the Air Mobility Command.

  16. Interplay between river discharge and tides in a delta distributary

    NASA Astrophysics Data System (ADS)

    Leonardi, Nicoletta; Kolker, Alexander S.; Fagherazzi, Sergio

    2015-06-01

    The hydrodynamics of distributary channels has tremendous impact on nutrient and dissolved oxygen circulation, transport of sediments, and delta formation and evolution; yet many processes acting at the river-marine interface of a delta are poorly understood. This paper investigates the combined effect of river hydrograph and micro-tides on the hydrodynamics of a delta distributary. As the ratio between river flow to tidal flow increases, tidal flood duration at the distributary mouth decreases, up to the point when flow reversal is absent. Field measurements in a distributary of the Apalachicola Delta, Florida, USA, reveal that, once the flow becomes unidirectional, high-discharge events magnify tidal velocity amplitudes. On the contrary, while the flow is bidirectional, increasing fluvial discharge decreases tidal velocity amplitudes down to a minimum value, reached at the limit between bidirectional and unidirectional flow. Due to the different response of the system to tides, the transition from a bidirectional to a unidirectional flow triggers a change in phase lag between high water and high water slack. In the presence of high riverine flow, tidal dynamics also promote seaward directed Eulerian residual currents. During discharge peaks, these residual currents almost double mean velocity values. Our results show that, even in micro-tidal environments, tides strongly impact distributary hydrodynamics during both high and low fluvial discharge regimes.

  17. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, is a valued area that can provide a range of services. We conducted a meta-analysis of existing studies done on the region to identify...

  18. Dermal absorption of the insecticide lindane (1 delta, 2 delta, 3 beta, 4 delta, 5 delta, 6 beta-hexachlorocyclohexane) in rats and rhesus monkeys: Effect of anatomical site

    SciTech Connect

    Moody, R.P.; Ritter, L. )

    1989-01-01

    Dermal absorption of the insecticide lindane (1 delta, 2 delta, 3 beta, 4 delta, 5 delta, 6 beta-hexachlorocyclohexane) was determined in rats and rhesus monkeys. Lindane is in widespread use as a 1% cream or lotion scabicide formulation and as a 1% miticide shampoo for body lice control in humans. Results obtained following our in vivo dermal absorption procedure demonstrated that 18 +/- 4.1%, 34 +/- 5.2%, and 54 +/- 26.3% of the applied dose was absorbed following topical applications at a rate of 1.5 micrograms/cm2 (6.2 micrograms/100 microliters of acetone) of the 14C-labeled pesticide to 4.2-cm2 regions of the forearm (n = 8), forehead (n = 7), and palm (n = 4) of rhesus monkeys, respectively. Dose sites were washed with soapy water 24 h posttreatment. Comparative studies in rats (n = 5) dosed middorsally demonstrated 31 +/- 9.5% absorption. Statistical analysis of the 14C excretion kinetics demonstrated slower clearance of lindane from rats than monkey forearm, forehead, or palm. Intramuscular (im) injections of 14C-lindane gave 52 +/- 7.1% recovery in monkey (n = 8) and 64 +/- 5.9% in rats (n = 5), suggesting body storage of this lipophilic chemical.

  19. "Delta Plots"--A New Way to Visualize Electronic Excitation.

    ERIC Educational Resources Information Center

    Morrison, Harry; And Others

    1985-01-01

    Presents procedures for obtaining and examples of delta plots (a way of illustrating electron density changes associated with electronic excitation). These plots are pedagogically useful for visualizing simple and complex transitions and provide a way of "seeing" the origin of highest occupied molecular orbital (HOMO)-dictated carbonyl…

  20. Upper Devonian deposystems of Catskill delta, West Virginia

    SciTech Connect

    Donaldson, A.C.; Lewis, J.S.; Mumcuoglu, C.; Boswell, R.; Peace, K.; Jewell. G.

    1984-12-01

    The oil and gas reservoir rocks of the Upper Devonian of West Virginia were deposited as shoreline sands along a coastal plain characterized by marine-dominant deltas (Catskill delta complex). The oil-bearing sandstones occur in strike trend (north-south) in north-central West Virginia connected by feeder channel sandstones with dip trends (east-west). In outcrop, the strike-trending sanstones contain occasional marine fossils, are well sorted, and exhibit sedimentary structures that suggest depositional environments ranging from shoreface to tidal delta and back barrier. Channel sandstones with herringbone bedding suggest tidal influence. These beds change to cross-bedding of unidirectional paleoflow origin in upstream fluvial counterparts of red-bed facies. The interpreted fluvial and tidal channels combine to represent distributary channels that supplied the sands to the barrier islands and delta front. Isolith maps show anastomosing belts trending east-west with both vertical and offset stacking. Stream avulsion and stream piracy probably account for lateral shifting of tidally influenced river distributaries. Gridlike patterns of sandstone belts result from the dynamic interference of tidal-fluvial channels with wave-constructed shoreline barrier islands and bars, complicated by onlap and offlap cycles. Subsurface informally named oil and gas sands generally are multiple sandstones.

  1. Water quality and ecology research in the Mississippi Delta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research by the USDA Agricultural Research Service (ARS) National Sedimentation Laboratory includes long-term and comprehensive evaluations of conservation practices and assessment of their influence on the water quality and biological health of watersheds in the Mississippi Delta alluvial plain, wi...

  2. Review: Advances in delta-subsidence research using satellite methods

    NASA Astrophysics Data System (ADS)

    Higgins, Stephanie A.

    2016-05-01

    Most of the world's major river deltas are sinking relative to local sea level. The effects of subsidence can include aquifer salinization, infrastructure damage, increased vulnerability to flooding and storm surges, and permanent inundation of low-lying land. Consequently, determining the relative importance of natural vs. anthropogenic pressures in driving delta subsidence is a topic of ongoing research. This article presents a review of knowledge with respect to delta surface-elevation loss. The field is rapidly advancing due to applications of space-based techniques: InSAR (interferometric synthetic aperture radar), GPS (global positioning system), and satellite ocean altimetry. These techniques have shed new light on a variety of subsidence processes, including tectonics, isostatic adjustment, and the spatial and temporal variability of sediment compaction. They also confirm that subsidence associated with fluid extraction can outpace sea-level rise by up to two orders of magnitude, resulting in effective sea-level rise that is one-hundred times faster than the global average rate. In coming years, space-based and airborne instruments will be critical in providing near-real-time monitoring to facilitate management decisions in sinking deltas. However, ground-based observations continue to be necessary for generating complete measurements of surface-elevation change. Numerical modeling should seek to simulate couplings between subsidence processes for greater predictive power.

  3. A vortex entrainment model applied to slender delta wings

    NASA Technical Reports Server (NTRS)

    Coe, P. L., Jr.

    1974-01-01

    A mathematical model of the vortex flow over a slender sharp-edged delta wing is proposed, and is shown to provide good agreement with the experiment. Although the technique requires experimental data in the form of the vortex core locations, it does account for the previously ignored mass entrainment of the vortex core.

  4. Obesity and Health Risk of Children in the Mississippi Delta

    ERIC Educational Resources Information Center

    Gamble, Abigail; Waddell, Dwight; Ford, M. Allison; Bentley, John P.; Woodyard, Catherine D.; Hallam, Jeffrey S.

    2012-01-01

    Background: Mississippi (MS) Delta adults and youth report obesity rates far exceeding those of the state and nation. State law requires in-school physical activity and nutrition practices to address childhood obesity but does not require evaluation of outcomes, specifically the impact on weight-related outcomes. This paper offers 3 things: (1)…

  5. Climbing Walls and Climbing Tuitions. A Delta Perspective

    ERIC Educational Resources Information Center

    Kirshstein, Rita J.; Kadamus, James A.

    2012-01-01

    High-end amenities like rock climbing walls on college campuses have become an easy target for those attempting to explain rising tuitions. This Delta Perspective looks beyond the media attention surrounding these "frills" to examine more serious questions about spending on campus facilities, college spending in general, and the real drivers of…

  6. Force Measurement on the GLAST Delta II Flight

    NASA Technical Reports Server (NTRS)

    Gordon, Scott; Kaufman, Daniel

    2009-01-01

    This viewgraph presentation reviews the interface force measurement at spacecraft separation of GLAST Delta II. The contents include: 1) Flight Force Measurement (FFM) Background; 2) Team Members; 3) GLAST Mission Overview; 4) Methodology Development; 5) Ground Test Validation; 6) Flight Data; 7) Coupled Loads Simulation (VCLA & Reconstruction); 8) Basedrive Simulation; 9) Findings; and 10) Summary and Conclusions.

  7. Overcoming the Education Challenge of Poverty in the Mississippi Delta

    ERIC Educational Resources Information Center

    Rutherford, Angela S.; Hillmer, Tamara; Parker, Ashley

    2011-01-01

    Tunica County, Mississippi, in the heart of the delta, has been home to stagnant academic achievement even as federal and state funds increased. A teacher-focused professional development program through the University of Mississippi helped yield higher scores and national recognition for an elementary school. It also revealed some learnings:…

  8. Population ecology of Aspergillus flavus associated with Mississippi Delta Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the source of Aspergillus flavus is required to effectively manage within-field aflatoxin contamination of maize (Zea mays L.). Studies assessed the density of A. flavus propagules and other soil microflora (Fusarium spp., total fungi) associated with Mississippi Delta soils, and corr...

  9. Evaluation Report: San Joaquin Delta College. Accreditation Report.

    ERIC Educational Resources Information Center

    San Joaquin Delta Coll., Stockton, CA.

    This report represents the findings of the evaluation team that visited San Joaquin Delta College on March 25-28, 1996 for the purpose of validating the college's application for reaffirmation of accreditation. Overall, the team was impressed with the high level of quality inherent throughout the college. However, the team identified a number of…

  10. Planning for the Future at San Joaquin Delta College.

    ERIC Educational Resources Information Center

    San Joaquin Delta Coll., Stockton, CA.

    This planning document provides data on current operations as of January 1994 and goals for the future at San Joaquin Delta College, in California. Section I, presents the context for planning at the college, describing the following major factors shaping the college's future: (1) the population is rapidly expanding; (2) fee increases and…

  11. Three Dimensional Morphodynamic and Vegetation Modeling of Wax Lake Delta

    NASA Astrophysics Data System (ADS)

    Khadka, A. K.; Meselhe, E. A.; Sadid, K. M.

    2013-12-01

    The Wax Lake Delta (WLD) is located at the downstream end of the Wax Lake outlet, approximately 13 miles upstream from Morgan City, Louisiana. In 1942 the United States Army Corps of Engineer (USACE) dredged Wax Lake Outlet channel from lower Atchafalaya River to reduce flood stages at Morgan City. The channel diverts 50% of Atchafalaya River water and sediment to WLD. Since 1942, the WLD has been building seaward due to the deposition of sediment at the channel mouth. Growth of this delta supports the concept of land building via river diversions. A process based morphodynamic model (Delft3D) with the ability to predict evolution of river-dominated deltas is used in this study to further our understanding of land-building and delta growth processes. Initial model bathymetry is prepared based on USACE hydrographic survey of 1998 along with LIDAR survey data for over bank areas. Two continuous gauges at Wax Lake outlet near Calumet and Atchafalaya Bay near Eugene Island are used to assign upstream inflow and outflow boundary conditions, respectively. The model is calibrated and validated for Hydrodynamics and Sediment transport through two sets of field observations for flooded and average conditions. Vertical velocity and suspended sediment profiles made in the channels of the WLD in 2000 and 2001 are used for the model calibration and validation. More comprehensive field observations are being gathered as part of an ongoing study funded by the National Science Foundation (FESD-Delta Dynamics Collaboratory). Data include mutli-beam bathymetric data, velocities, sediment, and nutrient concentrations in the channels as well as on top of the islands. The Delft3D morphodynamic model for WLD provides quantitative information regarding water and sediment distribution among the inter-connected channel bifurcations, the exchange of sediment and nutrients between the channels and islands. The model is being used to investigate the rate of land building and delta growth from

  12. The transmission of low frequency medical data using delta modulation techniques.

    NASA Technical Reports Server (NTRS)

    Arndt, G. D.; Dawson, C. T.

    1972-01-01

    The transmission of low-frequency medical data using delta modulation techniques is described. The delta modulators are used to distribute the low-frequency data into the passband of the telephone lines. Both adaptive and linear delta modulators are considered. Optimum bit rates to minimize distortion and intersymbol interference are discussed. Vibrocardiographic waves are analyzed as a function of bit rate and delta modulator configuration to determine their reproducibility for medical evaluation.

  13. Reducing Uncertainty for the DeltaQ Duct Leakage Test

    SciTech Connect

    Walker, Iain S.; Sherman, Max H.; Dickerhoff, Darryl J.

    2004-05-01

    The thermal distribution system couples the HVAC components to the building envelope, and shares many properties of the buildings envelope including moisture, conduction and most especially air leakage performance. Duct leakage has a strong influence on air flow rates through building envelopes (usually resulting in much greater flows than those due to natural infiltration) because unbalanced duct air flows and leaks result in building pressurization and depressurization. As a tool to estimate this effect, the DeltaQ duct leakage test has been developed over the past several years as an improvement to existing duct pressurization tests. It focuses on measuring the air leakage flows to outside at operating conditions that are required for envelope infiltration impacts and energy loss calculations for duct systems. The DeltaQ test builds on the standard envelope tightness blower door measurement techniques by repeating the tests with the system air handler off and on. The DeltaQ test requires several assumptions to be made about duct leakage and its interaction with the duct system and building envelope in order to convert the blower door results into duct leakage at system operating conditions. This study examined improvements to the DeltaQ test that account for some of these assumptions using a duct system and building envelope in a test laboratory. The laboratory measurements used a purpose-built test chamber coupled to a duct system typical of forced air systems in US homes. Special duct leaks with controlled air-flow were designed and installed into an airtight duct system. This test apparatus allowed the systematic variation of the duct and envelope leakage and accurate measurement of the duct leakage flows for comparison to DeltaQ test results. This paper will discuss the laboratory test apparatus design, construction and operation, the various analysis techniques applied to the calculation procedure and present estimates of uncertainty in measured duct

  14. Underground and Previously Undiscovered Rivers in the Mississippi Delta

    NASA Astrophysics Data System (ADS)

    Kolker, A.; Breaux, A.; Coleman, D.; Inniss, L. V.; Telfeyan, K.; Kim, J.; Schneider, A.; Allison, M. A.; Cable, J. E.; Johannesson, K. H.

    2013-12-01

    In this study we show that there are large, and previously undiscovered, groundwater pathways by which water from the Mississippi River is transported to the wetlands and estuaries of the Mississippi River Delta. Results from multiple methodologies suggest that the total flux of groundwater to the coastal zone in the Mississippi River Delta averages 1,000 m3 s-1, and can reach 5,000 m3 s-1 at high flow. We suggest that flow preferentially occurs through paleo-crevasse channels, relict bayous, and other buried deposits of permeable and coarse grained material. These conduits were formed during the present and previous stages of the delta cycle, which occurred in historical (102 y) and late Holocene(103 y) times, respectively. Flow is driven by the hydrological head difference between the river and the estuary, which is seasonally variable in magnitudeand can reach 5-8 m during peak river floods. This talk will present data from hydrological budgets that show a missing fraction in the Mississippi River water budget, and a missing source of fresh water to a large estuary. We will show that water levels in wells in New Orleans fluctuate with the stage of the Mississippi River. Data of Rn concentration indicate advective submarine groundwater flow, whereas Ba concentrations suggest geochemical leachates are entering the estuary. Furthermore, seismic data indicate the prevalence of paleochannels and other buried features that could carry flow. Given the importance of deltas to global geochemical budgets, we suggest that these results may be generalizable: submarine groundwater discharge in deltas may prove to be an important but understudied pathway by which dissolved materials are transported from the continents to the ocean.

  15. The functional significance of delta oscillations in cognitive processing

    PubMed Central

    Harmony, Thalía

    2013-01-01

    Ample evidence suggests that electroencephalographic (EEG) oscillatory activity is linked to a broad variety of perceptual, sensorimotor, and cognitive operations. However, few studies have investigated the delta band (0.5–3.5 Hz) during different cognitive processes. The aim of this review is to present data and propose the hypothesis that sustained delta oscillations inhibit interferences that may affect the performance of mental tasks, possibly by modulating the activity of those networks that should be inactive to accomplish the task. It is clear that two functionally distinct and potentially competing brain networks can be broadly distinguished by their contrasting roles in attention to the external world vs. the internally directed mentation or concentration. During concentration, EEG delta (1–3.5 Hz) activity increases mainly in frontal leads in different tasks: mental calculation, semantic tasks, and the Sternberg paradigm. This last task is considered a working memory task, but in neural, as well as phenomenological, terms, working memory can be best understood as attention focused on an internal representation. In the Sternberg task, increases in power in the frequencies from 1 to 3.90 Hz in frontal regions are reported. In a Go/No-Go task, power increases at 1 Hz in both conditions were observed during 100–300 ms in central, parietal and temporal regions. However, in the No-Go condition, power increases were also observed in frontal regions, suggesting its participation in the inhibition of the motor response. Increases in delta power were also reported during semantic tasks in children. In conclusion, the results suggest that power increases of delta frequencies during mental tasks are associated with functional cortical deafferentation, or inhibition of the sensory afferences that interfere with internal concentration. These inhibitory oscillations would modulate the activity of those networks that should be inactive to accomplish the task. PMID

  16. Aqueous Alteration at a Delta in Eastern Libya Montes

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Tirsch, Daniela; Tornabene, Livio L.; Seelos, Frank P.; Erkeling, Gino; Hiesinger, Harald; Jaumann, Ralf

    2015-04-01

    Libya Montes hosts ancient Noachian basalt altered by hydrothermal action from the Isidis impact, olivine- and pyroxene-bearing lavas from the Syrtis volcanic outflows, multiple craters that have excavated these geologic units, and numerous Hesperian-Amazonian-aged fluvial features that carved channels across the surface and may have transported material downward towards Isidis. Mineralogical analyses of a delta region in Eastern Libya Montes using recently available MTR3 CRISM images have revealed the presence of carbonate in additional to Al-, Fe-, and Mg-bearing phyllosilicates. We are investigating the origins of these aqueous components through stratigraphical and morphological analyses. We hypothesize that the carbonate and Fe/Mg-phyllosilicates are alteration products of the ancient basalt and that the Al-smectite formed as a result of the delta and more recent lacustrine or fluvial processes. The Al-smectite spectral features are most consistent with beidellite, which forms at elevated temperatures compared to montmorillonite. We seek to determine if the beidellite likely formed in warm delta waters or if it may have formed via burial diagenesis and was then excavated by the delta. Newly developed CRISM parameters are being utilized for analysis of the MTR3 versions of CRISM images FRT0000B0CB and FRT0001E2F2 in the fan and delta region of eastern Libya Montes. The MTR3 images feature joined short-wavelength and long-wavelength images and improved spectral signals through new atmospheric separation and noise removal techniques. This enables better detection of spectral signatures from small outcrops of aqueous components. We have placed these new CRISM mineral maps over HRSC stereo images to evaluate the stratigraphy of the aqueous components in relation to the ancient basalt and Syrtis lavas as in previous analyses of the central Libya Montes region. Coordinated CRISM-HiRISE views are expected to provide insights into the morphologies of the aqueous units

  17. Differential Entrainment of Neuroelectric Delta Oscillations in Developmental Dyslexia

    PubMed Central

    Soltész, Fruzsina; Szűcs, Denes; Leong, Victoria; White, Sonia; Goswami, Usha

    2013-01-01

    Oscillatory entrainment to the speech signal is important for language processing, but has not yet been studied in developmental disorders of language. Developmental dyslexia, a difficulty in acquiring efficient reading skills linked to difficulties with phonology (the sound structure of language), has been associated with behavioural entrainment deficits. It has been proposed that the phonological ‘deficit’ that characterises dyslexia across languages is related to impaired auditory entrainment to speech at lower frequencies via neuroelectric oscillations (<10 Hz, ‘temporal sampling theory’). Impaired entrainment to temporal modulations at lower frequencies would affect the recovery of the prosodic and syllabic structure of speech. Here we investigated event-related oscillatory EEG activity and contingent negative variation (CNV) to auditory rhythmic tone streams delivered at frequencies within the delta band (2 Hz, 1.5 Hz), relevant to sampling stressed syllables in speech. Given prior behavioural entrainment findings at these rates, we predicted functionally atypical entrainment of delta oscillations in dyslexia. Participants performed a rhythmic expectancy task, detecting occasional white noise targets interspersed with tones occurring regularly at rates of 2 Hz or 1.5 Hz. Both groups showed significant entrainment of delta oscillations to the rhythmic stimulus stream, however the strength of inter-trial delta phase coherence (ITC, ‘phase locking’) and the CNV were both significantly weaker in dyslexics, suggestive of weaker entrainment and less preparatory brain activity. Both ITC strength and CNV amplitude were significantly related to individual differences in language processing and reading. Additionally, the instantaneous phase of prestimulus delta oscillation predicted behavioural responding (response time) for control participants only. PMID:24204644

  18. Differential ontogeny of multiple opioid receptors (mu, delta, and kappa)

    SciTech Connect

    Spain, J.W.; Roth, B.L.; Coscia, C.J.

    1985-03-01

    We investigated the postnatal ontogeny of opioid receptors in rat brain under assay conditions which, when combined with computerized analysis, effectively reflect the developmental profile of high affinity binding to mu, delta, and kappa subpopulations. Concentrations of mu sites were assessed with the selective ligand /sup 3/H-(D-ala2,mePhe4,gly-ol5)enkephalin (DAGO). The other two sites were analyzed in binding assays with less selective radioligands but in the presence of specific unlabeled ligands which suppress cross-reactivity. We utilized /sup 3/H-(D-ala2,D-leu5)enkephalin (DADL) in the presence of 10 nM DAGO to label delta sites and /sup 3/H-ethylketocyclazocine (EKC) in the presence of 100 nM DADL + 100 nM (D-ala2,mePhe4,Met(0)ol5)enkephalin to detect kappa receptors. After birth, the density (femtomoles per milligram of wet weight) of mu sites declined for several days and then rose sharply over the next 2 weeks, increasing 2-fold by adulthood. Delta (delta) sites appeared in the second week postnatal and increased more than 8-fold in the next 2 weeks. Levels of kappa receptors were relatively low at birth and increased slowly (2-fold, overall). Computerized analyses of binding data revealed that DAGO and DADL were binding to single populations of sites throughout the postnatal period. DAGO and EKC affinities did not fluctuate in this period, whereas DADL affinities were low for the first week and then rose to adult levels. In summary, mu, kappa, and delta receptors exhibit differential postnatal developmental profiles. The former two are present at birth, whereas the latter appears in the second week. The postnatal increase for all three sites appear to be preceded by the previously demonstrated emergence of opioid peptides.

  19. 75 FR 34624 - Revocation of Class D and E Airspace; Big Delta, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-18

    ... airspace at Big Delta, AK (75 FR 17322). Controlled airspace serving Allen Army Airfield was revised in... TRANSPORTATION Federal Aviation Administration 14 CFR Part 71 Revocation of Class D and E Airspace; Big Delta, AK... Class D and E airspace at Big Delta, AK, to eliminate duplicated controlled airspace serving Allen...

  20. Constant sediment budget of Mekong delta shorelines: implications from long-term shoreline changes

    NASA Astrophysics Data System (ADS)

    Tamura, T.; Saito, Y.; Nguyen, V. L.; Ta, T. K. O.

    2015-12-01

    The sustainability of delta shorelines requires the sufficient sediment supply that is equal to or more than the sediment removal by tides and waves. The Mekong River delta, southern Vietnam, is a mixed-energy, complicated system with multiple delta plain shorelines that share the sediment supply from the river. We reconstructed the long-term shoreline changes of the Mekong delta over the last 2500 years based on the architecture and chronology of beach ridges on three delta plain in Ben Tre (North, Central, and South Ben Tre), and a delta plain in Tra Vinh to consider the sediment flux and its contribution to the growth of individual delta plains. While each delta plain shows temporal changes in growth rate, the sum of these four plains is nearly constant. This implies that the net sediment supply to the shorelines is constant, and that the geomorphological changes at distributary branches cause changes in sediment supply to each shoreline compartment. The distributary between North and Central Ben Tre was choked sometime between 500 and 1000 years ago, causing the rapid and stagnant shoreline progradation in North and Central Ben Tre, respectively. The shoreline of Central Ben Tre however has prograded slowly even after the choking, suggesting the beach sand can be supplied beyond the distributary or onshore from the delta front. Pre-industrial changes in delta geomorphology, based on geological records, improve the understanding of the delta systems and when compared with historical changes, diagnose the post-industrial state of delta.