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Sample records for bay impact structure

  1. Chesapeake Bay impact structure: A blast from the past

    Science.gov (United States)

    Powars, David S.; Edwards, Lucy E.; Gohn, Gregory S.; Horton, Jr., J. Wright

    2015-10-28

    About 35 million years ago, a 2-mile-wide meteorite smashed into Earth in what is now the lower Chesapeake Bay in Virginia. The oceanic impact vaporized, melted, fractured, and displaced rocks and sediments and sent billions of tons of water, sediments, and rocks into the air. Glassy particles of solidified melt rock rained down as far away as Texas and the Caribbean. Large tsunamis affected most of the North Atlantic basin. The resulting impact structure is more than 53 miles wide and has a 23-mile-wide, filled central crater surrounded by collapsed sediments. Now buried by hundreds of feet of younger sediments, the Chesapeake Bay impact structure is among the 20 largest known impact structures on Earth.

  2. Deep drilling in the Chesapeake Bay impact structure - An overview

    Science.gov (United States)

    Gohn, G.S.; Koeberl, C.; Miller, K.G.; Reimold, W.U.

    2009-01-01

    The late Eocene Chesapeake Bay impact structure lies buried at moderate depths below Chesapeake Bay and surrounding landmasses in southeastern Virginia, USA. Numerous characteristics made this impact structure an inviting target for scientific drilling, including the location of the impact on the Eocene continental shelf, its threelayer target structure, its large size (??85 km diameter), its status as the source of the North American tektite strewn field, its temporal association with other late Eocene terrestrial impacts, its documented effects on the regional groundwater system, and its previously unstudied effects on the deep microbial biosphere. The Chesapeake Bay Impact Structure Deep Drilling Project was designed to drill a deep, continuously cored test hole into the central part of the structure. A project workshop, funding proposals, and the acceptance of those proposals occurred during 2003-2005. Initial drilling funds were provided by the International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS). Supplementary funds were provided by the National Aeronautics and Space Administration (NASA) Science Mission Directorate, ICDP, and USGS. Field operations were conducted at Eyreville Farm, Northampton County, Virginia, by Drilling, Observation, and Sampling of the Earth's Continental Crust (DOSECC) and the project staff during September-December 2005, resulting in two continuously cored, deep holes. The USGS and Rutgers University cored a shallow hole to 140 m in April-May 2006 to complete the recovered section from land surface to 1766 m depth. The recovered section consists of 1322 m of crater materials and 444 m of overlying postimpact Eocene to Pleistocene sediments. The crater section consists of, from base to top: basement-derived blocks of crystalline rocks (215 m); a section of suevite, impact melt rock, lithic impact breccia, and cataclasites (154 m); a thin interval of quartz sand and lithic blocks (26 m); a

  3. Chesapeake Bay Impact Structure Deep Drilling Project Completes Coring

    Directory of Open Access Journals (Sweden)

    the Scientific Staff of the Chesapeake Bay Impact Structure Deep Drilling Project

    2006-09-01

    Full Text Available The Chesapeake Bay Impact Structure Deep Drilling Project (CBIS Project completed its coring operations during September–December 2005 and April–May 2006. Cores were collected continuously to a total depth of 1766 m. The recovered section consists of 1322 m of impactites beneath 444 m of post-impact continental shelf sediments.The CBIS Project is a joint venture of the International Continental Scientifi c Drilling Program (ICDP and the U.S. Geological Survey (USGS. Project activities began with a planning workshop in September 2003 attended by sixtythree scientists from ten countries. Field operations began with site preparation in July 2005, and coring began in September 2005. Drilling, Observation and Sampling of theEarth’s Continental Crust (DOSECC was the general contractor for the drilling operations throughout 2005.

  4. Chesapeake Bay impact structure: Morphology, crater fill, and relevance for impact structures on Mars

    Science.gov (United States)

    Horton, J.W.; Ormo, J.; Powars, D.S.; Gohn, G.S.

    2006-01-01

    The late Eocene Chesapeake Bay impact structure (CBIS) on the Atlantic margin of Virginia is one of the largest and best-preserved "wet-target" craters on Earth. It provides an accessible analog for studying impact processes in layered and wet targets on volatile-rich planets. The CBIS formed in a layered target of water, weak clastic sediments, and hard crystalline rock. The buried structure consists of a deep, filled central crater, 38 km in width, surrounded by a shallower brim known as the annular trough. The annular trough formed partly by collapse of weak sediments, which expanded the structure to ???85 km in diameter. Such extensive collapse, in addition to excavation processes, can explain the "inverted sombrero" morphology observed at some craters in layered targets. The distribution of crater-fill materials i n the CBIS is related to the morphology. Suevitic breccia, including pre-resurge fallback deposits, is found in the central crater. Impact-modified sediments, formed by fluidization and collapse of water-saturated sand and silt-clay, occur in the annular trough. Allogenic sediment-clast breccia, interpreted as ocean-resurge deposits, overlies the other impactites and covers the entire crater beneath a blanket of postimpact sediments. The formation of chaotic terrains on Mars is attributed to collapse due to the release of volatiles from thick layered deposits. Some flat-floored rimless depressions with chaotic infill in these terrains are impact craters that expanded by collapse farther than expected for similar-sized complex craters in solid targets. Studies of crater materials in the CBIS provide insights into processes of crater expansion on Mars and their links to volatiles. ?? The Meteoritical Society, 2006.

  5. Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

    Science.gov (United States)

    Declercq, J.; Dypvik, H.; Aagaard, P.; Jahren, J.; Ferrell, R.E.; Horton, J. Wright

    2009-01-01

    The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

  6. Monoclinic tridymite in clast-rich impact melt rock from the Chesapeake Bay impact structure

    Science.gov (United States)

    Jackson, J.C.; Horton, J.W.; Chou, I.-Ming; Belkin, H.E.

    2011-01-01

    X-ray diffraction and Raman spectroscopy confirm a rare terrestrial occurrence of monoclinic tridymite in clast-rich impact melt rock from the Eyreville B drill core in the Chesapeake Bay impact structure. The monoclinic tridymite occurs with quartz paramorphs after tridymite and K-feldspar in a microcrystalline groundmass of devitrified glass and Fe-rich smectite. Electron-microprobe analyses revealed that the tridymite and quartz paramorphs after tridymite contain different amounts of chemical impurities. Inspection by SEM showed that the tridymite crystal surfaces are smooth, whereas the quartz paramorphs contain irregular tabular voids. These voids may represent microporosity formed by volume decrease in the presence of fluid during transformation from tridymite to quartz, or skeletal growth in the original tridymite. Cristobalite locally rims spherulites within the same drill core interval. The occurrences of tridymite and cristobalite appear to be restricted to the thickest clast-rich impact melt body in the core at 1402.02-1407.49 m depth. Their formation and preservation in an alkali-rich, high-silica melt rock suggest initially high temperatures followed by rapid cooling.

  7. Impact of predation by Ostracion immaculatus (Pisces: Ostraciidae) on the macrofouling community structure in Kanayama Bay, Kii Peninsula (Japan)

    Digital Repository Service at National Institute of Oceanography (India)

    Raveendran, T.V.; Harada, E.

    An investigation on the impact of predation by Ostracion immaculatus on fouling community structure in Kanayama Bay, Kii Peninsula, Japan was undertaken from April 1994 to February 1995. Caging experiments with three size groups of O. immaculatus...

  8. Societal Implications of an Impact Crater - Chesapeake Bay Impact Structure, Virginia

    Science.gov (United States)

    Emry, S.; McFarland, R.; Powars, D.

    2002-05-01

    Ground water plays an important role in the economy and quality of life in the Coastal Plain of Virginia. In 1990, the aquifers in the Coastal Plain supplied over 100 million gallons of water per day to the citizens, businesses, and industries of Virginia. In southeastern Virginia, the thirteen public water utilities serve approximately 1.5 million people in the Hampton Roads area. The role of ground water resources in sustaining this area is more critical than ever due to the relatively low relief of the Coastal Plain Province, providing few new surface water sources to meet the growing population and expanding economy and the increased regulatory obstacles to obtaining a permit to build new reservoirs. A zone of salty ground water, referred to as the "inland salt water wedge," is well known to ground water resource planners and scientists, but until recently the phenomenon has not been satisfactorily explained. In 1996, the directors of the water utilities in Hampton Roads were introduced to the most dramatic geological event that ever took place in the Chesapeake Bay region. Geologists from the U.S. Geological Survey provided evidence of a meteor impact that formed a crater over 35 million years ago. The contours of the inland saltwater wedge conform well to the shape of the crater's outer rim. Prior to the discovery of the impact crater, it was presumed that the ground water flow in the Coastal Plain aquifer system was a relatively simple system described as "alternating layers of aquifers and confining units gradually dipping and thickening from the west to the east." With the discovery of the impact crater, the rules changed. In 1997, the USGS and the Hampton Roads Planning District Commission, representing the sixteen member jurisdictions, teamed up in a cooperative effort to redefine the hydrogeology of southeastern Virginia. In 1999, the Virginia Department of Environmental Quality and the Virginia Department of Mines, Minerals, and Energy joined the team

  9. Anatomy of the Chesapeake Bay impact structure revealed by seismic imaging, Delmarva Peninsula, Virginia, USA

    Science.gov (United States)

    Catchings, R.D.; Powars, D.S.; Gohn, G.S.; Horton, J.W.; Goldman, M.R.; Hole, J.A.

    2008-01-01

    A 30-km-long, radial seismic reflection and refraction survey completed across the northern part of the late Eocene Chesapeake Bay impact structure (CBIS) on the Delmarva Peninsula, Virginia, USA, confirms that the CBIS is a complex central-peak crater. We used a tomographic P wave velocity model and low-fold reflection images, constrained by data from two deep boreholes located on the profile, to interpret the structure and composition of the upper 5 km of crust. The seismic images exhibit well-defined structural features, including (with increasing radial distance) a collapsed central uplift, a breccia-filled moat, and a collapsed transient-crater margin (which collectively constitute a ???40-km-wide collapsed transient crater), and a shallowly deformed annular trough. These seismic images are the first to resolve the deep structure of the crater (>1 km) and the boundaries between the central uplift, moat, and annular trough. Several distinct seismic signatures distinguish breccia units from each other and from more coherent crystalline rocks below the central uplift, moat, and annular trough. Within the moat, breccia extends to a minimum depth of 1.5 km or a maximum of 3.5 km, depending upon the interpretation of the deepest layered materials. The images show ???350 to 500 m of postimpact sediments above the impactites. The imaged structure of the CBIS indicates a complex sequence of event during the cratering process that will provide new constraints for numerical modeling. Copyright 2008 by the American Geophysical Union.

  10. Origin and emplacement of impactites in the Chesapeake Bay impact structure, Virginia, USA

    Science.gov (United States)

    Horton, J.W.; Gohn, G.S.; Powars, D.S.; Edwards, L.E.

    2007-01-01

    The late Eocene Chesapeake Bay impact structure, located on the Atlantic margin of Virginia, may be Earth's best-preserved large impact structure formed in a shallow marine, siliciclastic, continental-shelf environment. It has the form of an inverted sombrero in which a central crater ???40 km in diameter is surrounded by a shallower brim, the annular trough, that extends the diameter to ???85 km. The annular trough is interpreted to have formed largely by the collapse and mobilization of weak sediments. Crystalline-clast suevite, found only in the central crater, contains clasts and blocks of shocked gneiss that likely were derived from the fragmentation of the central-uplift basement. The suevite and entrained megablocks are interpreted to have formed from impact-melt particles and crystalline-rock debris that never left the central crater, rather than as a fallback deposit. Impact-modified sediments in the annular trough include megablocks of Cretaceous nonmarine sediment disrupted by faults, fluidized sands, fractured clays, and mixed-sediment intercalations. These impact-modified sediments could have formed by a combination of processes, including ejection into and mixing of sediments in the water column, rarefaction-induced fragmentation and clastic injection, liquefaction and fluidization of sand in response to acoustic-wave vibrations, gravitational collapse, and inward lateral spreading. The Exmore beds, which blanket the entire crater and nearby areas, consist of a lower diamicton member overlain by an upper stratified member. They are interpreted as unstratified ocean-resurge deposits, having depositional cycles that may represent stages of inward resurge or outward anti-resurge flow, overlain by stratified fallout of suspended sediment from the water column. ?? 2008 The Geological Society of America. All rights reserved.

  11. Contamination assessment in microbiological sampling of the Eyreville core, Chesapeake Bay impact structure

    Science.gov (United States)

    Gronstal, A.L.; Voytek, M.A.; Kirshtein, J.D.; Von der, Heyde; Lowit, M.D.; Cockell, C.S.

    2009-01-01

    Knowledge of the deep subsurface biosphere is limited due to difficulties in recovering materials. Deep drilling projects provide access to the subsurface; however, contamination introduced during drilling poses a major obstacle in obtaining clean samples. To monitor contamination during the 2005 International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) deep drilling of the Chesapeake Bay impact structure, four methods were utilized. Fluorescent microspheres were used to mimic the ability of contaminant cells to enter samples through fractures in the core material during retrieval. Drilling mud was infused with a chemical tracer (Halon 1211) in order to monitor penetration of mud into cores. Pore water from samples was examined using excitation-emission matrix (EEM) fl uorescence spectroscopy to characterize dissolved organic carbon (DOC) present at various depths. DOC signatures at depth were compared to signatures from drilling mud in order to identify potential contamination. Finally, microbial contaminants present in drilling mud were identified through 16S ribosomal deoxyribonucleic acid (rDNA) clone libraries and compared to species cultured from core samples. Together, these methods allowed us to categorize the recovered core samples according to the likelihood of contamination. Twenty-two of the 47 subcores that were retrieved were free of contamination by all the methods used and were subsequently used for microbiological culture and culture-independent analysis. Our approach provides a comprehensive assessment of both particulate and dissolved contaminants that could be applied to any environment with low biomass. ?? 2009 The Geological Society of America.

  12. The Chesapeake Bay crater: geology and geophysics of a Late Eocene submarine impact structure

    Science.gov (United States)

    Poag, C. Wylie; Koeberl, Christian; Reimold, Wolf Uwe

    2004-01-01

    The list of impact craters documented on Earth is short. Only about 165 genuine impact structures have been identified to date (Table 1.1). Even so, the number is steadily increasing at the rate of ∼3–5 per year (Grieve et al. 1995; Earth Impact Database at http://www.unb.ca/passc/Impact/Database/). In stark contrast, most other rocky planets and satellites of our solar system are pockmarked by thousands to hundreds of thousands of impact features (Beatty et al. 1999). Nevertheless, impact specialists acknowledge that Earth, too, has undergone billions of years of bolide bombardment (Melosh 1989; Schoenberg et al. 2002). The most intense bombardment, however, took place during Earth’s earliest history (∼3.8–4 Ga; Ryder 1990; Cohen et al. 2000; Ryder et al. 2000). Traces of most terrestrial impacts have been completely erased or strongly altered by the dynamic processes of a thick atmosphere, deep ocean, and mobile crust, a combination unique to our planet. Planetary geologists now recognize that processes associated with bolide impacts are fundamental to planetary accretion and surface modification (Melosh 1989; Peucker-Ehrenbrink and Schmitz 2001). Incoming meteorites may have been primary sources for Earth’s water, and, perhaps, even organic life as we know it (Thomas et al. 1997; Kring 2000). There is little doubt that impacts played a major role in the evolution of Earth’s biota (Ryder et al. 1996; Hart 1996).

  13. Physical property data from the ICDP-USGS Eyreville cores A and B, Chesapeake Bay impact structure, Virginia, USA, acquired using a multisensor core logger

    Science.gov (United States)

    Pierce, H.A.; Murray, J.B.

    2009-01-01

    The International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS) drilled three core holes to a composite depth of 1766 m within the moat of the Chesapeake Bay impact structure. Core recovery rates from the drilling were high (??90%), but problems with core hole collapse limited the geophysical downhole logging to natural-gamma and temperature logs. To supplement the downhole logs, ??5% of the Chesapeake Bay impact structure cores was processed through the USGS GeoTek multisensor core logger (MSCL) located in Menlo Park, California. The measured physical properties included core thickness (cm), density (g cm-3), P-wave velocity (m s-1), P-wave amplitude (%), magnetic susceptibility (cgs), and resistivity (ohm-m). Fractional porosity was a secondary calculated property. The MSCL data-sampling interval for all core sections was 1 cm longitudinally. Photos of each MSCL sampled core section were imbedded with the physical property data for direct comparison. These data have been used in seismic, geologic, thermal history, magnetic, and gravity models of the Chesapeake Bay impact structure. Each physical property curve has a unique signature when viewed over the full depth of the Chesapeake Bay impact structure core holes. Variations in the measured properties reflect differences in pre-impact target-rock lithologies and spatial variations in impact-related deformation during late-stage crater collapse and ocean resurge. ?? 2009 The Geological Society of America.

  14. Evolution of crystalline target rocks and impactites in the chesapeake bay impact structure, ICDP-USGS eyreville B core

    Science.gov (United States)

    Horton, J.W.; Kunk, M.J.; Belkin, H.E.; Aleinikoff, J.N.; Jackson, J.C.; Chou, I.-Ming

    2009-01-01

    The 1766-m-deep Eyreville B core from the late Eocene Chesapeake Bay impact structure includes, in ascending order, a lower basement-derived section of schist and pegmatitic granite with impact breccia dikes, polymict impact breccias, and cataclas tic gneiss blocks overlain by suevites and clast-rich impact melt rocks, sand with an amphibolite block and lithic boulders, and a 275-m-thick granite slab overlain by crater-fill sediments and postimpact strata. Graphite-rich cataclasite marks a detachment fault atop the lower basement-derived section. Overlying impactites consist mainly of basement-derived clasts and impact melt particles, and coastalplain sediment clasts are underrepresented. Shocked quartz is common, and coesite and reidite are confirmed by Raman spectra. Silicate glasses have textures indicating immiscible melts at quench, and they are partly altered to smectite. Chrome spinel, baddeleyite, and corundum in silicate glass indicate high-temperature crystallization under silica undersaturation. Clast-rich impact melt rocks contain ??- cristobalite and monoclinic tridymite. The impactites record an upward transition from slumped ground surge to melt-rich fallback from the ejecta plume. Basement-derived rocks include amphibolite-facies schists, greenschist(?)-facies quartz-feldspar gneiss blocks and subgreenschist-facies shale and siltstone clasts in polymict impact breccias, the amphibolite block, and the granite slab. The granite slab, underlying sand, and amphibolite block represent rock avalanches from inward collapse of unshocked bedrock around the transient crater rim. Gneissic and massive granites in the slab yield U-Pb sensitive high-resolution ion microprobe (SHRIMP) zircon dates of 615 ?? 7 Ma and 254 ?? 3 Ma, respectively. Postimpact heating was 7lt;~350 ??C in the lower basementderived section based on undisturbed 40Ar/ 39Ar plateau ages of muscovite and <~150

  15. A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A

    Science.gov (United States)

    Jackson, J.C.; Horton, J.W.; Chou, I.-Ming; Belkin, H.E.

    2006-01-01

    A shock-induced polymorph (TiO2II) of anatase and rutile has been identified in breccias from the late Eocene Chesapeake Bay impact structure. The breccia samples are from a recent, partially cored test hole in the central uplift at Cape Charles, Virginia. The drill cores from 744 to 823 m depth consist of suevitic crystalline-clast breccia and brecciated cataclastic gneiss in which the TiO2 phases anatase and rutile are common accessory minerals. Electron-microprobe imaging and laser Raman spectroscopy of TiO2 crystals, and powder X-ray diffraction (XRD) of mineral concentrates, confirm that a high-pressure, ??-PbO2 structured polymorph of TiO2 (TiO2II) coexists with anatase and rutile in matrix-hosted crystals and in inclusions within chlorite. Raman spectra of this polymorph include strong bands at wavenumbers (cm-1) 175, 281, 315, 342, 356, 425, 531, 571, and 604; they appear with anatase bands at 397, 515, and 634 cm-1, and rutile bands at 441 and 608 cm-1. XRD patterns reveal 12 lines from the polymorph that do not significantly interfere with those of anatase or rutile, and are consistent with the TiO2II that was first reported to occur naturally as a shock-induced phase in rutile from the Ries crater in Germany. The recognition here of a second natural shock-induced occurrence of TiO2II suggests that its presence in rocks that have not been subjected to ultrahigh-pressure regional metamorphism can be a diagnostic indicator for confirmation of suspected impact structures.

  16. Polar organic compounds in pore waters of the Chesapeake Bay impact structure, Eyreville core hole: Character of the dissolved organic carbon and comparison with drilling fluids

    Science.gov (United States)

    Rostad, C.E.; Sanford, W.E.

    2009-01-01

    Pore waters from the Chesapeake Bay impact structure cores recovered at Eyreville Farm, Northampton County, Virginia, were analyzed to characterize the dissolved organic carbon. After squeezing or centrifuging, a small volume of pore water, 100 ??L, was taken for analysis by electrospray ionization-mass spectrometry. Porewater samples were analyzed directly without filtration or fractionation, in positive and negative mode, for polar organic compounds. Spectra in both modes were dominated by low-molecular-weight ions. Negative mode had clusters of ions differing by -60 daltons, possibly due to increasing concentrations of inorganic salts. The numberaverage molecular weight and weight-average molecular weight values for the pore waters from the Chesapeake Bay impact structure are higher than those reported for other aquatic sources of natural dissolved organic carbon as determined by electrospray ionization-mass spectrometry. In order to address the question of whether drilling mud fluids may have contaminated the pore waters during sample collection, spectra from the pore waters were compared to spectra from drilling mud fluids. Ions indicative of drilling mud fluids were not found in spectra from the pore waters, indicating there was no detectable contamination, and highlighting the usefulness of this analytical technique for detecting potential contamination during sample collection. ?? 2009 The Geological Society of America.

  17. Distribution, Origin, and Realtions to Flow of Salty Ground Water Along the Western Margin of the Chesapeake Bay Impact Structure in Eastern Virginia

    Science.gov (United States)

    McFarland, R.; Bruce, S.

    2002-05-01

    The Chesapeake Bay impact structure closely coincides with parts of some aquifers in eastern Virginia that contain saltwater as much as 30 miles landward of the coast. The impact structure has thereby been inferred to play some role in controlling the presence of this "inland saltwater wedge", which formed under unstressed conditions prior to present-day ground-water withdrawals. That the impact severely disrupted the previously stratified sediments casts doubt on conceptualizations of a regionally contiguous, vertically layered system of aquifers and confining units. In addition, large and increasing ground-water withdrawals have resulted in continuing water-level declines and altered flow directions that create the potential for saltwater intrusion. Hence, the origin and emplacement of the saltwater must be known to predict its reaction to stresses being placed upon the flow system. Specific conductances and concentrations of chloride in ground water along the western margin of the impact structure reflect a transitional interface between freshwater to the west and seawater to the east that coincides aerially with the margin of the impact structure. Ratios of bromide to chloride and chlorine-36 to total chloride, and of stable hydrogen and oxygen isotopes, indicate chloride to have originated primarily from mixing of freshwater and seawater across the interface. In addition, deep ground water east of the interface having specific conductances which exceed that of seawater likely resulted from partial evaporation of seawater, either (1) in restricted coastal environments under arid conditions, (2) by rapid vaporization caused by the impact event, and (or) (3) by residual heat and associated hydrothermal activity following the impact. Mixing of freshwater and seawater has been theorized to take place in a "differential flushing" manner that left residual seawater to form the saltwater wedge. Seawater emplaced during inundation of the land surface persisted around

  18. The Eocene-Oligocene sedimentary record in the Chesapeake Bay impact structure: Implications for climate and sea-level changes on the western Atlantic margin

    Science.gov (United States)

    Schulte, P.; Wade, B.S.; Kontny, A.; ,

    2009-01-01

    A multidisciplinary investigation of the Eocene-Oligocene transition in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville core from the Chesapeake Bay impact basin was conducted in order to document environmental changes and sequence stratigraphic setting. Planktonic foraminifera and calcareous nannofossil biostratigraphy indicate that the Eyreville core includes an expanded upper Eocene (Biozones E15 to E16 and NP19/20 to NP21, respectively) and a condensed Oligocene-Miocene (NP24-NN1) sedimentary sequence. The Eocene-Oligocene contact corresponds to a =3-Ma-long hiatus. Eocene- Oligocene sedimentation is dominated by great diversity and varying amounts of detrital and authigenic minerals. Four sedimentary intervals are identified by lithology and mineral content: (1) A 30-m-thick, smectite- and illite-rich interval directly overlies the Exmore Formation, suggesting long-term reworking of impact debris within the Chesapeake Bay impact structure. (2) Subsequently, an increase in kaolinite content suggests erosion from soils developed during late Eocene warm and humid climate in agreement with data derived from other Atlantic sites. However, the kaolinite increase may also be explained by change to a predominant sediment input from outside the Chesapeake Bay impact structure caused by progradation of more proximal facies belts during the highstand systems tract of the late Eocene sequence E10.Spectral analysis based on gamma-ray and magnetic susceptibility logs suggests infl uence of 1.2 Ma low-amplitude oscillation of the obliquity period during the late Eocene. (3) During the latest Eocene (Biozones NP21 and E16), several lithological contacts (clay to clayey silt) occur concomitant with a prominent change in the mineralogical composition with illite as a major component: This lithological change starts close to the Biozone NP19/20-NP21 boundary and may correspond to sequence boundary E10-E11 as observed in

  19. Rock-avalanche and ocean-resurge deposits in the late Eocene Chesapeake Bay impact structure: Evidence from the ICDP-USGS Eyreville cores, Virginia, USA

    Science.gov (United States)

    Gohn, G.S.; Powars, D.S.; Dypvik, H.; Edwards, L.E.

    2009-01-01

    An unusually thick section of sedimentary breccias dominated by target-sediment clasts is a distinctive feature of the late Eocene Chesapeake Bay impact structure. A cored 1766-m-deep section recovered from the central part of this marine-target structure by the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) drilling project contains 678 m of these breccias and associated sediments and an intervening 275-m-thick granite slab. Two sedimentary breccia units consist almost entirely of Cretaceous nonmarine sediments derived from the lower part of the target sediment layer. These sediments are present as coherent clasts and as autoclastic matrix between the clasts. Primary (Cretaceous) sedimentary structures are well preserved in some clasts, and liquefaction and fluidization structures produced at the site of deposition occur in the clasts and matrix. These sedimentary breccias are interpreted as one or more rock avalanches from the upper part of the transient-cavity wall. The little-deformed, unshocked granite slab probably was transported as part of an extremely large slide or avalanche. Water-saturated Cretaceous quartz sand below the slab was transported into the seafloor crater prior to, or concurrently with, the granite slab. Two sedimentary breccia units consist of polymict diamictons that contain cobbles, boulders, and blocks of Cretaceous nonmarine target sediments and less common shocked-rock and melt ejecta in an unsorted, unstratified, muddy, fossiliferous, glauconitic quartz matrix. Much of the matrix material was derived from Upper Cretaceous and Paleogene marine target sediments. These units are interpreted as the deposits of debris flows initiated by the resurge of ocean water into the seafloor crater. Interlayering of avalanche and debris-flow units indicates a partial temporal overlap of the earlier avalanche and later resurge processes. A thin unit of stratified turbidite deposits and overlying laminated

  20. Geologic columns for the ICDP-USGS Eyreville A and B cores, Chesapeake Bay impact structure: Sediment-clast breccias, 1096 to 444 m depth

    Science.gov (United States)

    Edwards, L.E.; Powars, D.S.; Gohn, G.S.; Dypvik, H.

    2009-01-01

    The Eyreville A and B cores, recovered from the "moat" of the Chesapeake Bay impact structure, provide a thick section of sediment-clast breccias and minor stratified sediments from 1095.74 to 443.90 m. This paper discusses the components of these breccias, presents a geologic column and descriptive lithologic framework for them, and formalizes the Exmore Formation. From 1095.74 to ??867 m, the cores consist of nonmarine sediment boulders and sand (rare blocks up to 15.3 m intersected diameter). A sharp contact in both cores at ??867 m marks the lowest clayey, silty, glauconitic quartz sand that constitutes the base of the Exmore Formation and its lower diamicton member. Here, material derived from the upper sediment target layers, as well as some impact ejecta, occurs. The block-dominated member of the Exmore Formation, from ??855-618.23 m, consists of nonmarine sediment blocks and boulders (up to 45.5 m) that are juxtaposed complexly. Blocks of oxidized clay are an important component. Above 618.23 m, which is the base of the informal upper diamicton member of the Exmore Formation, the glauconitic matrix is a consistent component in diamicton layers between nonmarine sediment clasts that decrease in size upward in the section. Crystalline-rock clasts are not randomly distributed but rather form local concentrations. The upper part of the Exmore Formation consists of crudely fining-upward sandy packages capped by laminated silt and clay. The overlap interval of Eyreville A and B (940-??760 m) allows recognition of local similarities and differences in the breccias. ?? 2009 The Geological Society of America.

  1. Geologic columns for the ICDP-USGS Eyreville A and C cores, Chesapeake Bay impact structure: Postimpact sediments, 444 to 0 m depth

    Science.gov (United States)

    Edwards, L.E.; Powars, D.S.; Browning, J.V.; McLaughlin, P.P.; Miller, K.G.; ,; Kulpecz, A.A.; Elbra, T.

    2009-01-01

    A 443.9-m-thick, virtually undisturbed section of postimpact deposits in the Chesapeake Bay impact structure was recovered in the Eyreville A and C cores, Northampton County, Virginia, within the "moat" of the structure's central crater. Recovered sediments are mainly fine-grained marine siliciclastics, with the exception of Pleistocene sand, clay, and gravel. The lowest postimpact unit is the upper Eocene Chickahominy Formation (443.9-350.1 m). At 93.8 m, this is the maximum thickness yet recovered for deposits that represent the return to "normal marine" sedimentation. The Drummonds Corner beds (informal) and the Old Church Formation are thin Oligocene units present between 350.1 and 344.7 m. Above the Oligocene, there is a more typical Virginia coastal plain succession. The Calvert Formation (344.7-225.4 m) includes a thin lower Miocene part overlain by a much thicker middle Miocene part. From 225.4 to 206.0 m, sediments of the middle Miocene Choptank Formation, rarely reported in the Virginia coastal plain, are present. The thick upper Miocene St. Marys and Eastover Formations (206.0-57.8 m) appear to represent a more complete succession than in the type localities. Correlation with the nearby Kiptopeke core indicates that two Pliocene units are present: Yorktown (57.8-32.2 m) and Chowan River Formations (32.2-18.3 m). Sediments at the top of the section represent an upper Pleistocene channel-fill and are assigned to the Butlers Bluff and Occohannock Members of the Nassawadox Formation (18.3-0.6 m). ?? 2009 The Geological Society of America.

  2. Comparison of clast frequency and size in the resurge deposits at the Chesapeake Bay impact structure (Eyreville A and Langley cores): Clues to the resurge process

    Science.gov (United States)

    Ormo, J.; Sturkell, E.; Horton, J.W.; Powars, D.S.; Edwards, L.E.

    2009-01-01

    Collapse and inward slumping of unconsolidated sedimentary strata expanded the Chesapeake Bay impact structure far beyond its central basement crater. During crater collapse, sediment-loaded water surged back to fill the crater. Here, we analyze clast frequency and granulometry of these resurge deposits in one core hole from the outermost part of the collapsed zone (i.e., Langley) as well as a core hole from the moat of the basement crater (i.e., Eyreville A). Comparisons of clast provenance and flow dynamics show that at both locations, there is a clear change in clast frequency and size between a lower unit, which we interpret to be dominated by slumped material, and an upper, water-transported unit, i.e., resurge deposit. The contribution of material to the resurge deposit was primarily controlled by stripping and erosion. This includes entrainment of fallback ejecta and sediments eroded from the surrounding seafloor, found to be dominant at Langley, and slumped material that covered the annular trough and basement crater, found to be dominant at Eyreville. Eyreville shows a higher content of crystalline clasts than Langley. There is equivocal evidence for an anti-resurge from a collapsing central water plume or, alternatively, a second resurge pulse, as well as a transition into oscillating resurge. The resurge material shows more of a debris-flow-like transport compared to resurge deposits at some other marine target craters, where the ratio of sediment to water has been relatively low. This result is likely a consequence of the combination of easily disaggregated host sediments and a relatively shallow target water depth. ?? 2009 The Geological Society of America.

  3. 77 FR 31353 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, AK

    Science.gov (United States)

    2012-05-25

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, AK AGENCY... of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' (EPA-910-R-12-004a-d). The... draft ``An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska''...

  4. Impact of Glider Data Assimilation on the Monterey Bay Model

    Science.gov (United States)

    2009-01-01

    Assimilation on the Monterey Bay Model 6. AUTHOR(S) Igor Shulman, Clark Rowley, Stephanie Anderson, Sergio DeRada, John Kindle, Paul Martin, James...Impact of glider data assimilation on the Monterey Bay model Igor Shulman3*, Clark Rowley3, Stephanie Andersona, Sergio DeRadaa, John Kindlea, Paul ...support of the AOSN-II field campaign. Deep-Sea Research II, this issue |doi:10.1016/j.dsr2.2008 08.009). Kundu. P.K.. 1976. Ekman veering observed

  5. 78 FR 25266 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

    Science.gov (United States)

    2013-04-30

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY... Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' (EPA-910-R-12-004Ba-c... on Salmon Ecosystems of Bristol Bay, Alaska'' is available primarily via the Internet on the...

  6. Impact of climate variability on an east Australian bay

    Science.gov (United States)

    Gräwe, U.; Wolff, J.-O.; Ribbe, J.

    2010-01-01

    The climate along the subtropical east coast of Australia is changing significantly. Rainfall has decreased by about 50 mm per decade and temperature increased by about 0.1 °C per decade during the last 50 years. These changes are likely to impact upon episodes of hypersalinity and the persistence of inverse circulations, which are often characteristic features of the coastal zone in the subtropics and are controlled by the balance between evaporation, precipitation, and freshwater discharge. In this study, observations and results from a general ocean circulation model are used to investigate how current climate trends have impacted upon the physical characteristics of the Hervey Bay, Australia. During the last two decades, mean precipitation in Hervey Bay deviates by 13% from the climatology (1941-2000). In the same time, the river discharge is reduced by 23%. In direct consequence, the frequency of hypersaline and inverse conditions has increased. Moreover, the salinity flux out of the bay has increased and the evaporation induced residual circulation has accelerated. Contrary to the drying trend, the occurrence of severe rainfalls, associated with floods, leads to short-term fluctuations in the salinity. These freshwater discharge events are used to estimate a typical response time for the bay.

  7. Evaluating the Impacts of Mangrove Rehabilitation in Cogtong Bay, Philippines

    Science.gov (United States)

    Maliao, Ronald J.; Polohan, Bernice B.

    2008-03-01

    Marine Protected Areas (MPAs) have been hailed worldwide as vehicles toward sustainable development (SD) in coastal zones. The prominent model by which MPAs operate is through a comanagement approach, a shift from traditional top-down management. This paradigm shift must be reviewed continuously to evaluate its social and ecological impacts, thereby allowing adaptive management. We evaluated the perceived impacts of the Cogtong Bay Mangrove Rehabilitation Project (CBMRP; Philippines) by using 12 perception indicators categorized into 3 comanagement impact criteria (equity, efficiency, and sustainability). We also collected 16 contextual attributes of each respondent to determine the correlates of perceived impacts. Our results showed that there were significant improvements in all indicators under the efficiency criterion but mixed impacts in the equity and sustainability criteria. Access to resource and household income (equity) and fisheries abundance (sustainability) were perceived to have decreased during the last 15 years and were not expected to improve in the future. Stepwise multiple regression analysis showed that the asymmetries of the perceived impacts of the CBMRP were principally caused by disparities in perceptions by gender and by location (Candijay and Mabini). This highlighted the importance of cross-scale institutional linkages between Cogtong Bay municipalities to systematically address baywide management issues. Our results further demonstrated the necessity of integrating gender issues into the evaluation of MPA impacts to ensure a robust evaluation. Finally, we recommend that a rigorous evaluation of MPAs using a common set of impact indicators should be encouraged to allow comparison of studies both spatially and temporally.

  8. 78 FR 34093 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

    Science.gov (United States)

    2013-06-06

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY... the revised draft document titled, ``An Assessment of Potential Mining Impacts on Salmon Ecosystems of... Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' is available primarily via the Internet...

  9. Impact of Ganges–Brahmaputra interannual discharge variations on Bay of Bengal salinity and temperature during 1992–1999 period

    Indian Academy of Sciences (India)

    Fabien Durand; Fabrice Papa; Atiqur Rahman; Sujit Kumar Bala

    2011-10-01

    This study investigates the impact of monthly Ganges–Brahmaputra river discharge variations on Bay of Bengal salinity and temperature during the period 1992–1999. The Ganges–Brahmaputra river discharge is characterized by a well-defined seasonal cycle with strong interannual variations. The highest/lowest yearly peak discharge occurs in summer 1998/summer 1992, with 1998 value amounting to twice that of 1992. This river discharge is then used to force an ocean general circulation model. Our main result is that the impact of these rivers on the variability of Bay of Bengal sea surface salinity is strong in the northern part, with excess run-off forcing fresh anomalies, and vice versa. Most of the years, the influence of the interannual variability of river discharge on the Bay salinity does not extend south of ∼10° N. This stands in contrast with the available observations and is probably linked to the relatively coarse resolution of our model. However, the extreme discharge anomaly of 1998 is exported through the southern boundary of the Bay and penetrates the south-eastern Arabian Sea a few months after the discharge peak. In response to the discharge anomalies, the model simulates significant mixed-layer temperature anomalies in the northern Bay of Bengal. This has the potential to influence the climate of the area. From our conclusions, it appears necessary to use a numerical model with higher resolution (both on the horizontal and vertical) to quantitatively investigate the upper Bay of Bengal salinity structure.

  10. Gulf of Mexico integrated science - Tampa Bay study, the impact of groundwater and contaminants on Tampa Bay

    Science.gov (United States)

    Swarzenski, Peter W.

    2005-01-01

    Despite the recreational and economic value of coastal bays and estuaries, these ecosystems are often among our most 'troubled' natural environments. Urbanization, agriculture, mining, and shipping are just a few activities that can have a profound and lasting impact on the coastal zone. In order to maintain a healthy coastal ecosystem, it is crucial to develop reasonable management practices around expert scientific information. We still have much to learn about the quantity and quality of groundwater being discharged into Tampa Bay, Florida. We also need to improve our knowledge of a wide range of contaminants entering the bay and must be able to determine where they accumulate in seafloor sediments. Such buried contaminants can potentially be harmful to biota if they are released to the water column. U.S. Geological Survey (USGS) scientists and research partners from the University of South Florida (USF), the University of Florida (UF), and the Florida Marine Research Institute (FMRI) are mapping sources of groundwater, measuring groundwater flow into Tampa Bay, and assessing the impact of contaminants and sediments on bay water quality and ecosystem health.

  11. Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville-B core, Chesapeake Bay impact structure

    Science.gov (United States)

    Townsend, Gabrielle N.; Gibson, Roger L.; Horton, J. Wright; Reimold, Wolf Uwe; Schmitt, Ralf T.; Bartosova, Katerina

    2009-01-01

    The Eyreville B core from the Chesapeake Bay impact structure, Virginia, USA, contains a lower basement-derived section (1551.19 m to 1766.32 m deep) and two megablocks of dominantly (1) amphibolite (1376.38 m to 1389.35 m deep) and (2) granite (1095.74 m to 1371.11 m deep), which are separated by an impactite succession. Metasedimentary rocks (muscovite-quartz-plagioclase-biotite-graphite ± fibrolite ± garnet ± tourmaline ± pyrite ± rutile ± pyrrhotite mica schist, hornblende-plagioclase-epidote-biotite-K-feldspar-quartz-titanite-calcite amphibolite, and vesuvianite-plagioclase-quartz-epidote calc-silicate rock) are dominant in the upper part of the lower basement-derived section, and they are intruded by pegmatitic to coarse-grained granite (K-feldspar-plagioclase-quartz-muscovite ± biotite ± garnet) that increases in volume proportion downward. The granite megablock contains both gneissic and weakly or nonfoliated biotite granite varieties (K-feldspar-quartz-plagioclase-biotite ± muscovite ± pyrite), with small schist xenoliths consisting of biotite-plagioclase-quartz ± epidote ± amphibole. The lower basement-derived section and both megablocks exhibit similar middle- to upper-amphibolite-facies metamorphic grades that suggest they might represent parts of a single terrane. However, the mica schists in the lower basement-derived sequence and in the megablock xenoliths show differences in both mineralogy and whole-rock chemistry that suggest a more mafic source for the xenoliths. Similarly, the mineralogy of the amphibolite in the lower basement-derived section and its association with calc-silicate rock suggest a sedimentary protolith, whereas the bulk-rock and mineral chemistry of the megablock amphibolite indicate an igneous protolith. The lower basement-derived granite also shows bulk chemical and mineralogical differences from the megablock gneissic and biotite granites.

  12. 75 FR 65373 - Drakes Bay Oyster Company Special Use Permit/Environmental Impact Statement, Point Reyes National...

    Science.gov (United States)

    2010-10-22

    ... National Park Service Drakes Bay Oyster Company Special Use Permit/Environmental Impact Statement, Point... Intent to prepare an Environmental Impact Statement for the Drakes Bay Oyster Company Special Use Permit... Statement (EIS) for the Drakes Bay Oyster Company Special Use Permit, Point Reyes National...

  13. Assessing mismatches between ecosystem structure and function in Jiaozhou Bay by coordination degree algorithm

    Science.gov (United States)

    Chen, Xiaoyan; Gao, Huiwang; Chen, Zhenhua; Yao, Xiaohong; Sun, Peng

    2017-04-01

    A healthy ecosystem depends on the coordination of ecosystem structure and function. The coordination among ecosystem components, however, is seldom taken into account in current ecosystem health assessments (EHA). Neglect of such coordination may lead to large degrees of uncertainty in EHA and fail to support ecosystem management. We propose an approach to quantify the level of dynamic mismatching between ecosystem structure and function and the impact on ecosystem health by incorporating the ecosystem coordination index into EHA. The coordination degree is calculated using variation coefficient of six proxies for ecosystem structure and functions. The ecosystem at Jiaozhou Bay, as a microcosm of China's coast, has been documented to fluctuate from healthy to unhealthy status over the past three decades. The results indicate that there is a 3%-17% lower health level than that calculated by common methods used in the literature, indicating that the health of Jiaozhou Bay has become worse than expected. Habitat change contributes 20%-52% to ecosystem mismatches and is the most uncoordinated factor. Mismatch-related declines account for approximately one-fourth of the total ecological declines. Restoration scenarios that aim to resolve ecosystem mismatches could increase efficiency by about 50% compared to restoration scenarios that do not consider mismatches. This study investigates ecological declines in a coastal bay due to 30 years of rapid economic development. In doing so, this study provides novel insights and enhances our understanding of the reasons for failure in ecological restoration.

  14. 76 FR 59423 - Drakes Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement, Point Reyes...

    Science.gov (United States)

    2011-09-26

    ... National Park Service Drakes Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement... statement to consider the Drakes Bay Oyster Company Special-use permit in Drakes Estero, Point Reyes... National Seashore Web site, at http://parkplanning.nps.gov/pore (click on the Drakes Bay Oyster...

  15. Structures of the Bohai Petroliferous Area, Bohai Bay Basin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper, for the first time, deals with a more systematic study of the structures in the Bohai petroliferous area that covers nearly one third of the Bohai Bay basin. The study mainly involves the effects of pre-existing basement faults on the basin formation, the characteristics of basin geometry and kinetics, the modelling of the tectonic-thermal history, the polycyclicity and heterogeneity in the structural evolution and the natural seismic tomographic images of the crust and upper mantle. The authors analyze the features of the dynamic evolution of the basin in the paper and point out that the basin in the Bohai petroliferous area is an extensional pull-apart basin.

  16. A discussion on typhoon occurred in the Haikou Bay and impact mechanism on seawater quality

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Water quality parameters such as pH, DO, COD, PO4 - P, SiO3 - Si, NO2 - N, NO3 -N in the Haikou Bay were monitored respectively before and after Typhoon 9618 occurring on Sep. 18,1996. Based on the statistics of typhoon in the Haikou Bay and numerical calculation of stormy current,the mechanism of water quality variation caused by typhoon is discussed. The typhoon impact on the Haikou Bay usually appears between July and November, most usually between August and October.The monitoring results before a typhoon were different from that. The stormy wave and windstorm cur rent stir up the sediment in near-shore bottom and make the bottom water mix with the surface water strongly, specially windstorm current with strong velocity at the head of the bay stirs up higher pollu tants sediment near sea area of sewage outfall, and heavy rain with typhoon carries the pollutants from land through the Nandu River to the Haikou Bay, so the contents of COD, PO4 - P, NO2 - N, NO3 -N, SiO3 after a typhoon are higher than those before. Windstorm current is violent, which makes offshore high DO water exchange more frequently with inner bay water and oxygen in the air dissolves in sea water faster, so DO content after typhoon is higher than that before typhoon. This strong action of water exchange also causes lower pH change before and after the typhoon.

  17. Indicators and impact analysis of sediment from the Changjiang Estuary and East China Sea to the Hangzhou Bay

    Institute of Scientific and Technical Information of China (English)

    WANG Hong; FAN Wei; YUN Caixing

    2004-01-01

    Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from the Changjiang Estuary and the East China Sea to the Hangzhou Bay are summarized. Numerical calculation and analysis indicate that the scouring and deposition of seabed in the Hangzhou Bay are subject to the direct impact of the evolution of the Changjiang Estuary, and the growth and decline and the direction of the sandy bar at Nanhuizui give traces to the sediment transport between the Changjiang Estuary and the Hangzhou Bay. The transport of sediment from the Changjiang Estuary to the Hangzhou Bay occurs mainly in winter and spring seasons and the increase of the Changjiang River runoff and the decrease of sediment charge have caused scouring in the northern coast of the Hangzhou Bay and the seabed erosion along the frontal margin of the Changjiang River Delta.

  18. The evaluation of fish farming impact by nutrient content and chlorophyll A in Mala Lamljana bay

    Directory of Open Access Journals (Sweden)

    Jelic-Mrcelic Gorana

    2013-01-01

    Full Text Available This paper offers a brief review of the impacts of fish farming on the nutrient content and chlorophyll a in Mala Lamljana Bay, Croatia. Local loading of nitrogen and phosphorous compounds in fish farms can be very significant and can represent the largest source of N and P in a given area. Low N and P concentrations, low chlorophyll a concentration and a great variety of phytoplankton species were found in the bay, despite the high nutrient loading during the long history of farming in the bay. The phytoplankton community consisted mostly of diatoms and partly of dinoflagellates. Skeletonema costatum and Chaetoceros compressus were the dominant species (90% in summer chlorophyll, which is typical for Middle Adriatic oligotrophic coastal waters. Nevertheless, further studies are required to determine changes in water column factors and planktonic communities in this area.

  19. Subsurface structure of the East Bay Plain ground-water basin: San Francisco Bay to the Hayward fault, Alameda County, California

    Science.gov (United States)

    Catchings, R.D.; Borchers, J.W.; Goldman, M.R.; Gandhok, G.; Ponce, D.A.; Steedman, C.E.

    2006-01-01

    The area of California between the San Francisco Bay, San Pablo Bay, Santa Clara Valley, and the Diablo Ranges (East Bay Hills), commonly referred to as the 'East Bay', contains the East Bay Plain and Niles Cone ground-water basins. The area has a population of 1.46 million (2003 US Census), largely distributed among several cities, including Alameda, Berkeley, Fremont, Hayward, Newark, Oakland, San Leandro, San Lorenzo, and Union City. Major known tectonic structures in the East Bay area include the Hayward Fault and the Diablo Range to the east and a relatively deep sedimentary basin known as the San Leandro Basin beneath the eastern part of the bay. Known active faults, such as the Hayward, Calaveras, and San Andreas pose significant earthquake hazards to the region, and these and related faults also affect ground-water flow in the San Francisco Bay area. Because most of the valley comprising the San Francisco Bay area is covered by Holocene alluvium or water at the surface, our knowledge of the existence and locations of such faults, their potential hazards, and their effects on ground-water flow within the alluvial basins is incomplete. To better understand the subsurface stratigraphy and structures and their effects on ground-water and earthquake hazards, the U.S. Geological Survey (USGS), in cooperation with the East Bay Municipal Utility District (EBMUD), acquired a series of high-resolution seismic reflection and refraction profiles across the East Bay Plain near San Leandro in June 2002. In this report, we present results of the seismic imaging investigations, with emphasis on ground water.

  20. The impact of physical processes on pollutant transport in Hangzhou Bay

    Institute of Scientific and Technical Information of China (English)

    LI Ning; MAO Zhihua; ZHANG Qinghe

    2009-01-01

    A Lagrangian tracer model is set up for Hangzhou Bay based on Coupled Hydrodynamical Ecological model for Regional Shelf Sea (COHERENS). The study area is divided into eight subdomains to identify the dominant physical processes, and the studied periods are March (the dry season) and July (the wet season). The model performance has been first verified by sea-surface elevation and tidal current observations at several stations. Eight tracer experiments are designed and Lagrangian particle tracking is simulated to examine the impact of physical processes (tide, wind and river runoff) on the transport of passive tracer released within the surface layer. Numerical simulations and analysis indicate that: (1) wind does not change the tracer distribution after 30 days except for those released from the south area of then bay during the wet season; (2) the tide and the Qiantang River runoff are important for particle transport in the head area of the bay; (3) the Changjiang River runoff affects the tracer transport at the mouth of the bay, and its impact is smaller in the dry season than in the wet season.

  1. Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation Stressors in Mobile Bay

    Science.gov (United States)

    Al-Hamdan, Mohammad; Estes, Maurice G., Jr.; Quattrochi, Dale; Thom, Ronald; Woodruff, Dana; Judd, Chaeli; Ellis, Jean; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

    2009-01-01

    Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land use change in Mobile and Baldwin counties on SAV stressors and controlling factors (temperature, salinity, and sediment) in Mobile Bay. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use scenarios in 1948, 1992, 2001, and 2030. Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the Bay. Theses results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid with four vertical profiles throughout Mobile Bay. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to land use driven flow changes with the restoration potential of SAVs.

  2. Linking structural equation modeling with Bayesian network and its application to coastal phytoplankton dynamics in the Bohai Bay

    Science.gov (United States)

    Xu, Xiao-fu; Sun, Jian; Nie, Hong-tao; Yuan, De-kui; Tao, Jian-hua

    2016-10-01

    Bayesian networks (BN) have many advantages over other methods in ecological modeling, and have become an increasingly popular modeling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modeling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in the Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models, and increases the BN model's accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in the Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, although the Redfield ratio indicates that phosphorus should be the primary nutrient limiting factor, our results show that silicate plays the most important role in regulating phytoplankton dynamics in the Bohai Bay.

  3. Grazing impact of microzooplankton on phytoplankton in the Xiamen Bay using pigment-specific dilution technique

    Institute of Scientific and Technical Information of China (English)

    HUANG Bangqin; LIU Yuan; XIANG Weiguo; TIAN Haojie; LIU Hongbin; CAO Zhenrui; HONG Huasheng

    2008-01-01

    Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography (HPLC) in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d -1 with the highest value occurred in the inner bay in May. Microzooplankton grazing rates ranged from 0.5 to 3.1 d-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate (up to 3.3 d -1 ) was recorded for diatoms in August, while the maximum grazing rate ( up to 2.1 d -1 ) was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes (83%) in August, while the maximum grazing pressure on primary production was observed for cyanobacteria (up to 151% ) in December in the inner bay. Net growth rates of larger phytoplanktons (diatoms and dinoflagellates) were higher than those of smaller groups (prasinophytes, chlorophytes and cyanobacteria). Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons ( December and February).

  4. A Model for the Formation of the Chesapeake Bay Impact Crater as Revealed by Drilling and Numerical Simulation

    Science.gov (United States)

    Collins, G. S.; Kenkmann, T.; Wünnemann, K.; Wittmann, A.; Reimold, W. U.; Melosh, H. J.

    The combination of numerical simulation results and petrographic analysis of drill core from the recent ICDP-USGS drilling project provides new insight into the formation of the Chesapeake Bay impact crater.

  5. Potential Impacts and Management Implications of Climate Change on Tampa Bay Estuary Critical Coastal Habitats

    Science.gov (United States)

    Sherwood, Edward T.; Greening, Holly S.

    2014-02-01

    The Tampa Bay estuary is a unique and valued ecosystem that currently thrives between subtropical and temperate climates along Florida's west-central coast. The watershed is considered urbanized (42 % lands developed); however, a suite of critical coastal habitats still persists. Current management efforts are focused toward restoring the historic balance of these habitat types to a benchmark 1950s period. We have modeled the anticipated changes to a suite of habitats within the Tampa Bay estuary using the sea level affecting marshes model under various sea level rise (SLR) scenarios. Modeled changes to the distribution and coverage of mangrove habitats within the estuary are expected to dominate the overall proportions of future critical coastal habitats. Modeled losses in salt marsh, salt barren, and coastal freshwater wetlands by 2100 will significantly affect the progress achieved in "Restoring the Balance" of these habitat types over recent periods. Future land management and acquisition priorities within the Tampa Bay estuary should consider the impending effects of both continued urbanization within the watershed and climate change. This requires the recognition that: (1) the Tampa Bay estuary is trending towards a mangrove-dominated system; (2) the current management paradigm of "Restoring the Balance" may no longer provide realistic, attainable goals; (3) restoration that creates habitat mosaics will prove more resilient in the future; and (4) establishing subtidal and upslope "refugia" may be a future strategy in this urbanized estuary to allow sensitive habitat types (e.g., seagrass and salt barren) to persist under anticipated climate change and SLR impacts.

  6. Population structure and maturity stages of Fritillaria borealis (Appendicularia, Tunicata: seasonal cycle in Ushuaia Bay (Beagle Channel

    Directory of Open Access Journals (Sweden)

    María Laura Presta

    2015-09-01

    Full Text Available AbstractFritillaria borealis is a cosmopolitan species, very frequent in sub-antarctic and antarctic waters. The objective of this paper was to analyze its size structure and maturity stages at two sites in Ushuaia Bay: a coastal site exposed to anthropogenic pressure (E1 and a reference site (E2 located in the external zone of the bay. Zooplankton was collected during the 2012 seasonal cycle. The sampling method involved the use of a 67 µm-mesh net. Appendicularians were classified in four maturity stages: I undifferentiated gonads, II testis and ovary differentiated, III expanded testis, IV discharged testis, expanded ovary. Our results showed that the highest densities of F. borealisoccurred in spring and summer at both sites; coinciding with high values of chlorophyll-a. The percentage of juveniles (I and II exhibited a spatial and temporal pattern similar to that observed for chlorophyll-a values. During spring-summer, juveniles and mature specimens (III and IV showed a greater gonadal development than those individuals found in autumn-winter. In conclusion, the mismatching in the population structure and the pattern of densities of F. borealis between coastal and external zones would suggest the existence of two sub-populations susceptible to the influence of the anthropogenic impact in the bay.

  7. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  8. Structured Additive Regression Models: An R Interface to BayesX

    Directory of Open Access Journals (Sweden)

    Nikolaus Umlauf

    2015-02-01

    Full Text Available Structured additive regression (STAR models provide a flexible framework for model- ing possible nonlinear effects of covariates: They contain the well established frameworks of generalized linear models and generalized additive models as special cases but also allow a wider class of effects, e.g., for geographical or spatio-temporal data, allowing for specification of complex and realistic models. BayesX is standalone software package providing software for fitting general class of STAR models. Based on a comprehensive open-source regression toolbox written in C++, BayesX uses Bayesian inference for estimating STAR models based on Markov chain Monte Carlo simulation techniques, a mixed model representation of STAR models, or stepwise regression techniques combining penalized least squares estimation with model selection. BayesX not only covers models for responses from univariate exponential families, but also models from less-standard regression situations such as models for multi-categorical responses with either ordered or unordered categories, continuous time survival data, or continuous time multi-state models. This paper presents a new fully interactive R interface to BayesX: the R package R2BayesX. With the new package, STAR models can be conveniently specified using Rs formula language (with some extended terms, fitted using the BayesX binary, represented in R with objects of suitable classes, and finally printed/summarized/plotted. This makes BayesX much more accessible to users familiar with R and adds extensive graphics capabilities for visualizing fitted STAR models. Furthermore, R2BayesX complements the already impressive capabilities for semiparametric regression in R by a comprehensive toolbox comprising in particular more complex response types and alternative inferential procedures such as simulation-based Bayesian inference.

  9. Updated Fiscal Impact Analysis, Naval Submarine Base, Kings Bay, Georgia

    Science.gov (United States)

    1986-12-01

    It also uses the grade structure of the inmigrating Navy personnel to 4-3- calculate the salaries that will be brought to the area. The population and...of inmigrants who wish to work. The FIA model treats the labor market as a dynamic condition that varies with base load-up and multiplier changes...Florida and Georgia (see the map on Figure 1-1). The selection of these counties was based on preliminary information about where the inmigrating

  10. The Chesapeake Bay Impact Crater: An Educational Investigation for Students into the Planetary Impact Process and its Environmental Consequences

    Science.gov (United States)

    Levine, Arlene S.

    2008-01-01

    Planetary impact craters are a common surface feature of many planetary bodies, including the Earth, the Moon, Mars, Mercury, Venus, and Jupiter s moons, Ganymede and Callisto. The NASA Langley Research Center in Hampton, VA, is located about 5 km inside the outer rim of the Chesapeake Bay Impact Crater. The Chesapeake Bay Impact Crater, with a diameter of 85 km is the sixth largest impact crater on our planet. The U.S. Geological Survey (USGS), in collaboration with the NASA Langley Research Center, the Virginia Department of Environmental Quality (VDEQ), the Hampton Roads Planning District Commission (HRPDC), and the Department of Geology of the College of William and Mary (WM) drilled into and through the crater at the NASA Langley Research Center and obtained a continuous core to a depth of 2075.9 ft (632.73 meters) from the Chesapeake Bay Impact Crater. At the NASA Langley location, the granite basement depth was at 2046 ft (623.87 meters). This collaborative drilling activity provided a unique educational opportunity and ongoing educational partnership between USGS, NASA Langley and the other collaborators. NASA Langley has a decade-long, ongoing educational partnership with the Colonial Coast Council of the Girl Scouts. The core drilling and on site analysis and cataloguing of the core segments provided a unique opportunity for the Girl Scouts to learn how geologists work in the field, their tools for scientific investigation and evaluation, how they perform geological analyses of the cores in an on-site tent and learn about the formation of impact craters and the impact of impacting bodies on the sub-surface, the surface, the oceans and atmosphere of the target body. This was accomplished with a two-part activity. Girl Scout day camps and local Girl Scout troops were invited to Langley Research Center Conference Center, where more than 300 Girl Scouts, their leaders and adult personnel were given briefings by scientists and educators from the USGS, NASA

  11. Built-up Al-Li structures for cryogenic tank and dry bay applications

    Science.gov (United States)

    Lisagor, W. Barry

    1993-02-01

    The objectives are: (1) to demonstrate the cost benefits of built-up cryotank and dry bay structures; (2) to study of benefits of using Al alloys; (3) to study of benefit of using Al-Li alloys; (4) to evaluate alternative low-cost stiffener and joining concepts.

  12. Built-up Al-Li structures for cryogenic tank and dry bay applications

    Science.gov (United States)

    Lisagor, W. Barry

    1993-01-01

    The objectives are: (1) to demonstrate the cost benefits of built-up cryotank and dry bay structures; (2) to study of benefits of using Al alloys; (3) to study of benefit of using Al-Li alloys; (4) to evaluate alternative low-cost stiffener and joining concepts.

  13. Internal structure of the 85°E ridge, Bay of Bengal: Evidence for multiphase volcanism

    Digital Repository Service at National Institute of Oceanography (India)

    Ismaiel, M.; Krishna, K.S.; Srinivas, K.; Mishra, J.; Saha, D.

    The 85°E Ridge, located in the Bay of Bengal of the northeastern Indian Ocean is an enigmatic geological feature as it possesses unusual geophysical signatures. The ridge's internal structure and mode of eruptions are unknown due to lack of deep...

  14. Bay-scale population structure in coastal Atlantic cod in Labrador and Newfoundland, Canada

    DEFF Research Database (Denmark)

    Ruzzante, D.E.; Wroblewski, J.S.; Taggart, C.T.;

    2000-01-01

    of population structure suggest that important barriers to gene flow exist among five components that include two inshore (Gilbert and Trinity Bay) and three offshore cod aggregations on the north-east Newfoundland Shelf and the Grand Bank. D-A and D-SW estimates of genetic distance that involve Gilbert Bay cod...... fishery collapse. Harvesting strategies for northern cod should recognize the existence of genetic diversity between inshore and offshore components as well as among coastal components. (C) 2000 The Fisheries Society of the British Isles...

  15. Lituya Bay Landslide Impact Generated Mega-Tsunami 50th Anniversary

    Science.gov (United States)

    Fritz, Hermann M.; Mohammed, Fahad; Yoo, Jeseon

    2009-02-01

    On July 10, 1958, an earthquake Mw 8.3 along the Fairweather fault triggered a major subaerial landslide into Gilbert Inlet at the head of Lituya Bay on the southern coast of Alaska. The landslide impacted the water at high speed generating a giant tsunami and the highest wave runup in recorded history. The mega-tsunami runup to an elevation of 524 m caused total forest destruction and erosion down to bedrock on a spur ridge in direct prolongation of the slide axis. A cross section of Gilbert Inlet was rebuilt at 1:675 scale in a two-dimensional physical laboratory model based on the generalized Froude similarity. A pneumatic landslide tsunami generator was used to generate a high-speed granular slide with controlled impact characteristics. State-of-the-art laser measurement techniques such as particle image velocimetry (PIV) and laser distance sensors (LDS) were applied to the decisive initial phase with landslide impact and wave generation as well as the runup on the headland. PIV provided instantaneous velocity vector fields in a large area of interest and gave insight into kinematics of wave generation and runup. The entire process of a high-speed granular landslide impact may be subdivided into two main stages: (a) Landslide impact and penetration with flow separation, cavity formation and wave generation, and (b) air cavity collapse with landslide run-out and debris detrainment causing massive phase mixing. Formation of a large air cavity — similar to an asteroid impact — in the back of the landslide is highlighted. A three-dimenional pneumatic landslide tsunami generator was designed, constructed and successfully deployed in the tsunami wave basin at OSU. The Lituya Bay landslide was reproduced in a three-dimensional physical model at 1:400 scale. The landslide surface velocities distribution was measured with PIV. The measured tsunami amplitude and runup heights serve as benchmark for analytical and numerical models.

  16. Impact of hydrotalcite deposition on biogeochemical processes in a shallow tropical bay.

    Science.gov (United States)

    Alongi, Daniel M; McKinnon, A David

    2011-03-01

    The biogeochemistry of a tropical shoal bay (Melville Bay, Australia) impacted by the effluent release, precipitation, and deposition of hydrotalcite from an alumina refinery was studied in both wet and dry seasons. Within the deposition zone, sulfate reduction dominated benthic carbon cycling accounting for ≈100% of total microbial activity, with rates greater than those measured in most other marine sediments. These rapid rates of anoxic metabolism resulted in high rates of sulfide and ammonium production and low C:S ratios, implying significant preservation of S in stable sulfide minerals. Rates of total microbial activity were significantly less in control sediments of equivalent grain size, where sulfate reduction accounted for ≈50% of total benthic metabolism. Rates of planktonic carbon cycling overlying the deposition zone were also greater than those measured in the control areas of southern Melville Bay. At the sediment surface, productive algal and cyanobacterial mats helped stabilize the sediment surface and oxidize sulfide to sulfate to maintain a fully oxygenated water-column overlying the impacted zone. The mats utilized a significant fraction of dissolved inorganic N and P released from the sea bed; some nutrients escaped to the water-column such that benthic regeneration of NH₄+ and PO₄³⁻ accounted for 100% and 42% of phytoplankton requirements for N and P, respectively. These percentages are high compared to other tropical coastal environments and indicate that benthic nutrient recycling may be a significant factor driving water-column production overlying the deposition zone. With regard to remediation, it is recommended that the sea bed not be disturbed as attempts at removal may result in further environmental problems and would require specific assessment of the proposed removal process.

  17. Impacts of mariculture practices on the temporal distribution of macrobenthos in Sandu Bay, South China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jin

    2012-01-01

    Sandu Bay is located in the East China Sea and is characterized by high-density fish farming and kelp culture.Despite this,little is known about the impacts of these different mariculture practices on the local environment.We investigated the temporal variation in macrobenthos and environmental conditions at three sites in the bay (fish farming site,kelp culture site,and a control site).We collected water and sediment samples during nine cruises between May 2009 and February 2010.The density ofmacrobenthos peaked at the fish farming site in July (655 ind./m2) whereas density did not fluctuate as widely at the other two sites.Biomass varied significantly at both the control and kelp culture sites,but had only a single peak at the fish farming site in June (21.90 g/m2).The dominant species varied throughout the study period at the control and kelp culture sites,whereas a single terebellid species (Lysilla pacifica) dominated the macrobenthos at the fish farming site.The diversity index H' increased at the control site beginning in February then decreased after May,whereas H' was low at the other sites in December.The mean dissolved oxygen level was highest at the control site (6.59 mg/L) and lowest at the fish farming site (5.54 mg/L).DO levels were lowest at all sites in summer (July and August).The sediment acid volatile sulfide content was higher at the fish farming site (1.46 mg/g dry weight) than those at the kelp culture and control sites (1.22 and 0.14 mg/g,respectively).Our results suggest that mariculture practices have a clear impact on the benthic environment/ community in Sandu Bay.

  18. Bay in Flux: Marine Climate Impacts, Art and Tablet App Design

    Science.gov (United States)

    Kintisch, E. S.

    2012-12-01

    Bay in Flux is a year-long experimental effort to design and develop interactive tablet computer apps exploring the marine impacts of climate change. The goal is to convey, visualize and enliven scientific ideas around this topic, while engaging a broad audience through the design of interactive content. Pioneering new models of scientist-artist collaborations are a central part of the effort as well. The project begins with an innovative studio class at the Rhode Island School of Design (RISD) called Bay in Flux, taught in the Fall 2012 semester. Its three instructor team includes two artist-designers and one science reporter, with active collaborations from affiliated marine scientists. The subject matter focus is the Narragansett Bay, which has shown physical, chemical and ecological impacts of climate change, along with the ongoing efforts of researchers to explain and characterize it. In exploring this rich story, we intend to innovate pioneering means of handling narrative material on interactive e-books, enable data collection by citizen scientists or devise game-like simulations to enable audiences to explore and understand complex natural systems. The lessons we seek to learn in this project include: how to effectively encourage collaborations between scientists and designers around digital design; how to pioneer new and compelling ways to tell science-based nonfiction stories on tablets; and how art and design students with no scientific training can engage with complex scientific content effectively. The project will also challenge us to think about the tablet computer not only as a data output device -- in which the user reads, watches, or interacts with provided content -- but also as a dynamic and ideal tool for mobile data input, enabling citizen science projects and novel connections between working researchers and the public. The intended audience could include high school students or older audiences who currently eschew science journalism. HTML5

  19. Community structure of macrozoobenthic feeding guilds in responses to eutrophication in Jakarta Bay

    Directory of Open Access Journals (Sweden)

    AM AZBAS TAURUSMAN

    2010-07-01

    Full Text Available Taurusman AA (2010 Community structure of macrozoobenthic feeding guilds in responses to eutrophication in Jakarta Bay. Biodiversitas 11: 133-138. The group of benthic fauna which feed on the same food sources are classified as a feeding guild. The objective of the present study was to evaluate the distribution and composition of macrozoobenthic feeding guilds along gradient of organic enrichment (trophic states in Jakarta Bay. The result of the present study was shown that at the hypertrophic stations of the bay dominated by species of surface deposit feeding polychaetes such as, Dodecaceria sp., Cirratulus sp., Capitella sp., and Spionidae. The eutrophic zone of the bay was dominated by suspension feeding bivalves Mactra sp., Chione sp. The offshore area (mesotrophic zone showed a high diversity of species and feeding guilds compared to other areas. The patterns of feeding guilds in the mesotrophic zone indicated a higher stability of macrozoobenthos community, indicated by the presence of deep-deposit feeder (e.g. Acetes sp., surface deposit feeders (e.g. Prionospio sp., suspension feeders (e.g. Chione sp., and carnivores (e.g. Nepthys sp. in comparable proportions. The structure of macrozoobenthic feeding guilds in an eutrophic coastal water is positively related to the quantity and quality of organic matters (eutrophic states, and the capability of benthic species in adaptation to such environmental condition.

  20. CALCULATED MOLECULAR STRUCTURES AND POTENTIAL ENERGY FUNCTIONS OF PAHS WITH METHYL CROWDING IN THE BAY REGION AND THEIR METABOLITES: COMPARISON TO EXPERIMENTAL STRUCTURES

    Science.gov (United States)

    Calculated molecular structures and potential energy functions ofP AHs with methyl crowding in the bay region and their metabolites: Comparison to experimental structures PAHs with methyl group substitution near a bay region represent a class of chemicals associated with ...

  1. Adapting Bayes Network Structures to Non-stationary Domains

    DEFF Research Database (Denmark)

    Nielsen, Søren Holbech; Nielsen, Thomas Dyhre

    2008-01-01

    When an incremental structural learning method gradually modifies a Bayesian network (BN) structure to fit a sequential stream of observations, we call the process structural adaptation. Structural adaptation is useful when the learner is set to work in an unknown environment, where a BN...

  2. Flood impacts in Keppel Bay, southern great barrier reef in the aftermath of cyclonic rainfall.

    Science.gov (United States)

    Jones, Alison M; Berkelmans, Ray

    2014-01-01

    In December 2010, the highest recorded Queensland rainfall associated with Tropical Cyclone 'Tasha' caused flooding of the Fitzroy River in Queensland, Australia. A massive flood plume inundated coral reefs lying 12 km offshore of the Central Queensland coast near Yeppoon and caused 40-100% mortality to coral fringing many of the islands of Keppel Bay down to a depth of ∼8 m. The severity of coral mortality was influenced by the level of exposure to low salinity seawater as a result of the reef's distance from the flood plume and to a lesser extent, water depth and whether or not the reef faced the plume source. There was no evidence in this study of mortality resulting from pollutants derived from the nearby Fitzroy Catchment, at least in the short term, suggesting that during a major flood, the impact of low salinity on corals outweighs that of pollutants. Recovery of the reefs in Keppel Bay from the 2010/2011 Fitzroy River flood is likely to take 10-15 years based on historical recovery periods from a similar event in 1991; potentially impacting visitor numbers for tourism and recreational usage. In the meantime, activities like snorkeling, diving and coral viewing will be focused on the few shallow reefs that survived the flood, placing even further pressure on their recovery. Reef regeneration, restoration and rehabilitation are measures that may be needed to support tourism in the short term. However, predictions of a warming climate, lower rainfall and higher intensity summer rain events in the Central and Coastal regions of Australia over the next decade, combined with the current anthropogenic influences on water quality, are likely to slow regeneration with consequent impact on long-term reef resilience.

  3. Flood impacts in Keppel Bay, southern great barrier reef in the aftermath of cyclonic rainfall.

    Directory of Open Access Journals (Sweden)

    Alison M Jones

    Full Text Available In December 2010, the highest recorded Queensland rainfall associated with Tropical Cyclone 'Tasha' caused flooding of the Fitzroy River in Queensland, Australia. A massive flood plume inundated coral reefs lying 12 km offshore of the Central Queensland coast near Yeppoon and caused 40-100% mortality to coral fringing many of the islands of Keppel Bay down to a depth of ∼8 m. The severity of coral mortality was influenced by the level of exposure to low salinity seawater as a result of the reef's distance from the flood plume and to a lesser extent, water depth and whether or not the reef faced the plume source. There was no evidence in this study of mortality resulting from pollutants derived from the nearby Fitzroy Catchment, at least in the short term, suggesting that during a major flood, the impact of low salinity on corals outweighs that of pollutants. Recovery of the reefs in Keppel Bay from the 2010/2011 Fitzroy River flood is likely to take 10-15 years based on historical recovery periods from a similar event in 1991; potentially impacting visitor numbers for tourism and recreational usage. In the meantime, activities like snorkeling, diving and coral viewing will be focused on the few shallow reefs that survived the flood, placing even further pressure on their recovery. Reef regeneration, restoration and rehabilitation are measures that may be needed to support tourism in the short term. However, predictions of a warming climate, lower rainfall and higher intensity summer rain events in the Central and Coastal regions of Australia over the next decade, combined with the current anthropogenic influences on water quality, are likely to slow regeneration with consequent impact on long-term reef resilience.

  4. Transportation impacts to wildlife on state route 37 in northern San Pablo Bay, California

    Science.gov (United States)

    Winton, Bryan R.; Takekawa, John Y.

    2002-01-01

    State Route 37 bisects conservation lands managed by San Pablo Bay National Wildlife Refuge (U.S. Fish & Wildlife Service) and Napa-Sonoma Marshes Wildlife Area (California Department of Fish and Game) in Solano and Sonoma Counties. The 2-lane highway connects Interstates 101 and 80 in northern San Francisco Bay and experiences ~26,000 vehicles per day. Road-killed wildlife between Napa River and Tolay Creek bridges (14.7 km) were counted in 2000 to ascertain species composition, relative abundance, and relative occurence (animal fatality interval). The primary objectives of the study were to determine if endangered salt marsh harvest mice (Reithrodontomys raviventris), California clapper rails (Rallus longirostris), or other species of concern were represented, and to collect baseline data on transportation impacts to wildlife in the area. During 51 surveys, 291 dead birds (54.6%) and mammals (45.4%) were observed. Endangered species were not positively identified dead on the highway. In total, 28 bird, 10 mammal and 1 reptile species were positively identified along this section of highway that traverses tidal marsh and diked baylands (i.e., salt ponds, seasonal wetlands, and oat-hay agriculture fields). The mean animal fatality interval for both lanes was one road-kill every 2.1km (2.1 km SD).

  5. Seasonal variation and structure of a decapod (Crustacea) assemblage living in a Caulerpa prolifera meadow in Cádiz Bay (SW Spain)

    Science.gov (United States)

    López De La Rosa, Inmaculada; Rodríguez, Antonio; García Raso, J. Enrique

    2006-02-01

    The decapod taxocoenosis living in shallow muddy bottoms with the green algae Caulerpa prolifera was studied monthly between February 1994 and January 1996 in the Inner Bay of Cádiz (SW Spain). More than 32,000 specimens belonging to 35 species were collected. Six species were dominant (representing the 85.8% of the total number of specimens), but the structure of the taxocoenosis was regulated by the Hippolyte species, Sicyonia carinata, Palaemon adspersus and Liocarcinus arcuatus. There was no significant qualitative difference between years. There was no clear change in the dominance of groups of species during the year, as happened in the outer Bay. This is probably due to the sheltered character of the area and the more stable and dense vegetal cover, but some seasonal differences were found. The benthic characteristics of the Inner Bay of Cádiz, such as shallow soft bottoms of fine and muddy sediments and the presence of macrophytes (seagrasses and seaweeds) might be key factors influencing the composition and structure of the general and seasonal decapod assemblage. In spite of human impacts on the bay (e.g. aquaculture activities, sewage), the values of the diversity, equitability and richness indexes appeared stable over time (higher than those found in outer adjacent areas) and no significant differences between years were found.

  6. The increasing impact of food production on nutrient export by rivers to the Bay of Bengal 1970–2050

    NARCIS (Netherlands)

    Sattar, M.A.; Kroeze, C.; Strokal, M.

    2014-01-01

    The objective of this study is to assess the impact of food production on river export of nutrients to the coastal waters of the Bay of Bengal in the past (1970 and 2000) and the future (2030 and 2050), and the associated potential for coastal eutrophication. We model nutrient export from land to se

  7. 77 FR 33213 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska-Peer Review...

    Science.gov (United States)

    2012-06-05

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska--Peer Review... availability and public comment period. SUMMARY: EPA is announcing the peer review panel members assembled by... three week public comment period for the draft charge questions to be provided to the peer review...

  8. The impact of glacier meltwater on the underwater noise field in a glacial bay

    Science.gov (United States)

    Glowacki, Oskar; Moskalik, Mateusz; Deane, Grant B.

    2016-12-01

    Ambient noise oceanography is proving to be an efficient and effective tool for the study of ice-ocean interactions in the bays of marine-terminating glaciers. However, obtaining quantitative estimates of ice melting or calving processes from ambient noise requires an understanding of how sound propagation through the bay attenuates and filters the noise spectrum. Measurements of the vertical structure in sound speed in the vicinity of the Hans Glacier in Hornsund Fjord, Spitsbergen, made with O(130) CTD casts between May and November 2015, reveal high-gradient, upward-refracting sound speed profiles created by cold, fresh meltwater during summer months. Simultaneous recordings of underwater ambient noise made at depths of 1, 10, and 20 m in combination with propagation model calculations using the model Bellhop illustrate the dominant role these surface ducts play in shaping the underwater soundscape. The surface ducts lead to a higher intensity and greater variability of acoustic energy in the near-surface layer covered by glacially modified waters relative to deeper waters, indicating deeper zones as most appropriate for interseasonal acoustic monitoring of the glacial melt. Surface waveguides in Hornsund are relatively shallow and trap sound above O(1 kHz). Deeper waveguides observed elsewhere will also trap low-frequency sounds, such as those generated by calving events for example. Finally, the ambient noise field in Hornsund is shown to be strongly dependent on the distribution of ice throughout the bay, stressing the importance of performing complementary environmental measurements when interpreting the results of acoustic surveys.

  9. The structure and origin of Prydz Bay and MacRobertson Shelf, East Antarctica

    Science.gov (United States)

    Stagg, H. M. J.

    1985-04-01

    -Prydz Bay structure as a possible failed rift arm of a triple junction. Direct information on the age and nature of the sediments under Prydz Bay is lacking, but Permian continental sediments cropping out at Beaver Lake, to the south, may correspond to the lower pre-breakup series. This interpretation gains some support from analogies with fault-bounded intracratonic basins in India which contain Permian to Triassic continental strata and which may have been juxtaposed prior to breakup. The upper series probably consists of Upper Cretaceous and Cainozoic sands and shales, with moraines or tillites at the top of the section.

  10. Gravity anomalies and crustal structure of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, V.; Krishna, K.S.; Murthy, I.V.R.; Sarma, K.V.L.N.S.; Desa, M.; Ramana, M.V.; KameshRaju, K.A.

    could not be explained by an isolated geophysical model invoking a negative density contrast for the ridge material. The 85 degrees E Ridge anomaly and several other isolated gravity lows are attributed mostly to the depression-like structures...

  11. Multiscale Reduced Order Modeling of Complex Multi-Bay Structures

    Science.gov (United States)

    2013-07-01

    indeed achieved with both enrichments. Manuscript Click here to download Manuscript: ROM_Notch_final2.pdf Click here to view linked References 1... brick elements (CHEXA in NX/Nastran), and 14 such elements were used along the width of the beam. Along the length, the notched beam was divided in...not a long body problem. Therefore, the structure was discretized throughout its entire domain with 8-node brick elements (CHEXA in NX/Nastran

  12. Impacts of enhanced central Pacific ENSO on wave climate and headland-bay beach morphology

    Science.gov (United States)

    Mortlock, Thomas R.; Goodwin, Ian D.

    2016-06-01

    Wave climate and Pacific basin coastal behaviour associated with El Niño Southern Oscillation (ENSO) is understood at a reconnaissance level, but the coastal response to different central Pacific (CP) versus eastern Pacific (EP) flavours of ENSO is unknown. We show that CP ENSO events produce different patterns of directional wave power to EP ENSO along the southeast Australian shelf and southwest Pacific region, because of significant variability in trade-wind wave generation. The modulation of the trade wind wave climate during CP ENSO has thus far been neglected in existing coastal process studies. We also show that coastal change between CP and EP ENSO cannot be inferred from shifts in the deepwater wave climate. This is because variability in trade wind wave generation is masked in deepwater by the persistence of high power extra-tropical waves that have reduced impact on nearshore processes due to high wave refraction. Morphodynamic modelling in a headland-bay beach indicates that CP ENSO leads to higher coastal erosion potential and slower post-storm recovery than EP ENSO during an El Niño/La Niña cycle. We show that the alongshore variability in beach morphological type can be used to model the static equilibrium planform response for each ENSO phase. Results indicate that shoreline response to ENSO in most headland-bay beach coasts is not as simple as the existing paradigm that (anti-) clockwise rotation occurs during El Niño (La Niña). Our methods provide a second-order approach to project coastal response and predict the discrete shoreline rotations for ENSO flavours.

  13. Paleoproterozoic Collisional Structures in the Hudson Bay Lithosphere Constrained by Multi-Observable Probabilistic Inversion

    Science.gov (United States)

    Darbyshire, F. A.; Afonso, J. C.; Porritt, R. W.

    2015-12-01

    The Paleozoic Hudson Bay intracratonic basin conceals a Paleoproterozoic Himalayan-scale continental collision, the Trans-Hudson Orogen (THO), which marks an important milestone in the assembly of the Canadian Shield. The geometry of the THO is complex due to the double-indentor geometry of the collision between the Archean Superior and Western Churchill cratons. Seismic observations at regional scale show a thick, seismically fast lithospheric keel beneath the entire region; an intriguing feature of recent models is a 'curtain' of slightly lower wavespeeds trending NE-SW beneath the Bay, which may represent the remnants of more juvenile material trapped between the two Archean continental cores. The seismic models alone, however, cannot constrain the nature of this anomaly. We investigate the thermal and compositional structure of the Hudson Bay lithosphere using a multi-observable probabilistic inversion technique. This joint inversion uses Rayleigh wave phase velocity data from teleseismic earthquakes and ambient noise, geoid anomalies, surface elevation and heat flow to construct a pseudo-3D model of the crust and upper mantle. Initially a wide range of possible mantle compositions is permitted, and tests are carried out to ascertain whether the lithosphere is stratified with depth. Across the entire Hudson Bay region, low temperatures and a high degree of chemical depletion characterise the mantle lithosphere. Temperature anomalies within the lithosphere are modest, as may be expected from a tectonically-stable region. The base of the thermal lithosphere lies at depths of >250 km, reaching to ~300 km depth in the centre of the Bay. Lithospheric stratification, with a more-depleted upper layer, is best able to explain the geophysical data sets and surface observables. Some regions, where intermediate-period phase velocities are high, require stronger mid-lithospheric depletion. In addition, a narrow region of less-depleted material extends NE-SW across the Bay

  14. Impact of continental outflow on chemistry of atmospheric aerosols over tropical Bay of Bengal

    Directory of Open Access Journals (Sweden)

    B. Srinivas

    2011-07-01

    Full Text Available The continental outflow from Indo-Gangetic Plain and south-east Asia dominates the widespread dispersal of pollutants over tropical Bay of Bengal (BoB during the late NE-monsoon (January–March. It is thus pertinent to assess the impact on marine atmospheric boundary layer of BoB. The chemical data, based on analyses of size-segregated (PM2.5 and PM10 aerosols, suggest the dominance of nss-SO42− (range: 1.3 to 28 μg m−3 in PM2.5. Almost all SO42− is of anthropogenic origin and accounts for as much as 65 % of the water-soluble inorganic constituents. The impact of anthropogenic sources is further evident from the widespread depletion of chloride (range: 40 to 100 % compared to sea-salt composition. The carbonaceous species (EC and OC contribute nearly 25 % to PM2.5; and significant linear relationship with K+ suggests biomass burning as their dominant source (biofuels and agricultural waste. The enhancement in the fractional solubility of aerosol Fe, as assessed in PM2.5, re-emphasizes the impact of combustion sources (biomass and fossil-fuel and chemical processing (of dust during the long-range transport. The high enrichment factors of heavy metals (Pb and Cd further demonstrate the influence of pollution sources on the chemistry of MABL. The downwind transport of pollutants and exchange across air-sea interface can, thus, have profound impact on the ocean surface biogeochemistry.

  15. USGS Tampa Bay Pilot Study

    Science.gov (United States)

    Yates, K.K.; Cronin, T. M.; Crane, M.; Hansen, M.; Nayeghandi, A.; Swarzenski, P.; Edgar, T.; Brooks, G.R.; Suthard, B.; Hine, A.; Locker, S.; Willard, D.A.; Hastings, D.; Flower, B.; Hollander, D.; Larson, R.A.; Smith, K.

    2007-01-01

    Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the Tampa Bay watershed, and the population constitutes to grow. Demand for freshwater resources, conversion of undeveloped areas to resident and industrial uses, increases in storm-water runoff, and increased air pollution from urban and industrial sources are some of the known human activities that impact Tampa Bay. Beginning on 2001, additional anthropogenic modifications began in Tampa Bat including construction of an underwater gas pipeline and a desalinization plant, expansion of existing ports, and increased freshwater withdrawal from three major tributaries to the bay. In January of 2001, the Tampa Bay Estuary Program (TBEP) and its partners identifies a critical need for participation from the U.S. Geological Survey (USGS) in providing multidisciplinary expertise and a regional-scale, integrated science approach to address complex scientific research issue and critical scientific information gaps that are necessary for continued restoration and preservation of Tampa Bay. Tampa Bay stakeholders identified several critical science gaps for which USGS expertise was needed (Yates et al. 2001). These critical science gaps fall under four topical categories (or system components): 1) water and sediment quality, 2) hydrodynamics, 3) geology and geomorphology, and 4) ecosystem structure and function. Scientists and resource managers participating in Tampa Bay studies recognize that it is no longer sufficient to simply examine each of these estuarine system components individually, Rather, the interrelation among system components must be understood to develop conceptual and

  16. San Diego Bay National Wildlife Refuge: Sweetwater Marsh and South San Diego Bay Units: Comprehensive Conservation Plan and Environmental Impact Statement: Volume I

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on San Diego Bay NWR (Sweetwater Marsh and South San Diego Bay Units) for the next 15...

  17. Impact of Megha-Tropiques SAPHIR radiance assimilation on the simulation of tropical cyclones over Bay of Bengal

    Science.gov (United States)

    Dhanya, M.; Gopalakrishnan, Deepak; Chandrasekar, Anantharaman; Singh, Sanjeev Kumar; Prasad, V. S.

    2016-05-01

    Impact of SAPHIR radiance assimilation on the simulation of tropical cyclones over Indian region has been investigated using the Weather Research and Forecasting (WRF) model. Three cyclones that formed over Bay of Bengal have been considered in the present study. Assimilation methodology used here is the three dimensional variational (3DVar) scheme within the WRF model. With the initial and boundary conditions from Global Forecasting System (GFS) analyses from the National Centres for Environmental Prediction (NCEP), a control run (CTRL) without assimilation of any data and a 3DVar run with the assimilation of SAPHIR radiance have been performed. Both model simulations have been compared with the observations from India Meteorological Department (IMD), Tropical Rainfall Measurement Mission (TRMM), and analysis fields from GFS. Detailed analysis reveals that, the SAPHIR radiance assimilation has led to significant improvement in the simulation of all the three cyclones in terms of cyclone track, intensity, accumulated rainfall. The simulation of warm core structure and relative vorticity profile of each cyclone by 3DVar run are found to be more closer to GFS analyses, when compared with the CTRL run.

  18. Study and review on crust-mantle velocity structure in Bohai Bay and its vicinity

    Institute of Scientific and Technical Information of China (English)

    张成科; 张先康; 赵金仁; 任青芳; 张建狮; 海燕

    2002-01-01

    Observational data from some of the 10-odd deep seismic sounding profiles in Bohai Bay and its adjacent areas were processed with the methods of two-dimensional ray tracing, travel-time fitting and synthetic seismogram. The crust and upper-mantle velocity structure model in this area was built. The results show that the crust and upper mantle structures present obvious lateral and vertical inhomogeneity. The upper mantle uplifts near Yongqing of northeast Jizhong depression, in Bohai Bay of Huanghua depression and near Kenli of Jiyang depression, where crustal depths are about 31 km, 28 km and 29 km, respectively. According to the dynamic and kinetic characteristics of seismic waves as well as the seismic interfaces and velocity contour undulation in the 2-D velocity structure model, three deep crustal fault zones are inferred in the area. Low velocity (5.90~6.10 km/s) layers (bodies) exist on one or two sides of these deep crustal fault zones.

  19. An analysis of urban development and its environmental impact on the Tampa Bay watershed

    Science.gov (United States)

    Xian, G.; Crane, M.; Su, J.

    2007-01-01

    Urbanization has transformed natural landscapes into anthropogenic impervious surfaces. Urban land use has become a major driving force for land cover and land use change in the Tampa Bay watershed of west-central Florida. This study investigates urban land use change and its impact on the watershed. The spatial and temporal changes, as well as the development density of urban land use are determined by analyzing the impervious surface distribution using Landsat satellite imagery. Population distribution and density are extracted from the 2000 census data. Non-point source pollution parameters used for measuring water quality are analyzed for the sub-drainage basins of Hillsborough County. The relationships between 2002 urban land use, population distribution and their environmental influences are explored using regression analysis against various non-point source pollutant loadings in these sub-drainage basins. The results suggest that strong associations existed between most pollutant loadings and the extent of impervious surface within each sub-drainage basin in 2002. Population density also exhibits apparent correlations with loading rates of several pollutants. Spatial variations of selected non-point source pollutant loadings are also assessed. ?? 2006 Elsevier Ltd. All rights reserved.

  20. Seismically induced soft-sediment deformation structures in the Palaeogene deposits of the Liaodong Bay Depression in the Bohai Bay basin and their spatial stratigraphic distribution

    Science.gov (United States)

    Liu, Lei; Zhong, Yijiang; Chen, Hongde; Xu, Changgui; Wu, Kui

    2016-08-01

    Soft-sediment deformation structures (SSDS) have been identified from well cores in the Palaeogene deposits of the Liaodong Bay Depression in the Bohai Bay basin, China. These deposits formed as interbedded sand and mud at a delta front or on the slope toe of the prodelta. According to criteria proposed by previous research, we established that these SSDS were induced by earthquakes and that they can be divided into two groups: ductile deformation structures (plastic intrusions, ball-and-pillow structures, flame structures, boudinage structures, irregular convolute stratifications, and synsedimentary faults and folds) and brittle deformation structures (sand dykes and autoclastic breccias). Based on their level of deformation, size, and complexity, the SSDS were divided into three Groups, from weak to strong, to reflect the intensity of palaeo-earthquakes. With consideration of the palaeo-sedimentary environment, we proposed a model to account for the production and preservation of these SSDS. According to the classification adopted in this study and the spatial stratigraphic distribution of the SSDS, the tectonic activities of the Tan-Lu faults in the Bohai Bay basin were investigated. The A and B oilfields (assumed names) are located in the tectonically active zones of the west and east branches of these faults, respectively. The extension tectonic activities in the A oilfield region exhibit a sharply decreasing trend from E2s3 to E2s1, and increase again in E3d2; whereas the strike-slip tectonic activities in the B oilfield region exhibit an increasing trend from E2s3 to E2s1, and finally, reach a maximum to E3d3. The results of this study show that the method of analysis of the spatial stratigraphic distribution of SSDS is suitable for determining the evolution of tectonic activity and thus, it can provide a new perspective for basin analysis.

  1. High Energy Wide Area Blunt Impact on Composite Aircraft Structures

    Science.gov (United States)

    DeFrancisci, Gabriela K.

    The largest source of damage to commercial aircraft is caused by accidental contact with ground service equipment (GSE). The cylindrical bumper typically found on GSE distributes the impact load over a large contact area, possibly spanning multiple internal structural elements (frame bays) of a stiffened-skin fuselage. This type of impact can lead to damage that is widespread and difficult to detect visually. To address this problem, monolithic composite panels of various size and complexity have been modeled and tested quasi-statically and dynamically. The experimental observations have established that detectability is dependent on the impact location and immediately-adjacent internal structure of the panel, as well as the impactor geometry and total deformation of the panel. A methodology to model and predict damage caused by wide area blunt impact events was established, which was then applied to more general cases that were not tested in order to better understand the nature of this type of impact event and how it relates to the final damage state and visual detectability.

  2. Atmospheric outflow of Nutrients to the Bay of Bengal: Impact of continental sources

    Science.gov (United States)

    Sarin, Manmohan; Srinivas, Bikkina

    2014-05-01

    The air-sea deposition of nutrients (N, P and Fe) to the oceanic regions located downwind of pollution sources in south Asia is gaining considerable attention in the present-day scenario of climate change. We report here a case study on the abundances of nutrients, their sources and temporal variability in the atmospheric outflow from the Indo-Gangetic Plain (IGP) to the Bay of Bengal (BoB). Air mass back trajectory analysis suggests conspicuous downwind transport of chemical constituents from the IGP to BoB during the late NE-monsoon (January-April). During rest of the year, wind-regimes do not favour the atmospheric transport from the IGP, making BoB a unique oceanic region in the global perspective. Concentrations of NO3-, NH4+, NOrg, PO43- and Fews in the atmospheric outflow from the IGP, studied during November'09 - March'10, show pronounced temporal variability. The inorganic nitrogen dominates (NH4+-N: ~ 90 % of NInorg) the total soluble nitrogen (NTot). Although the contribution of organic nitrogen is not significant, the mass ratio of NOrg/NTot in the outflow varied from 0.07 to 0.40. The abundances of PInorg and Fews varied from 0.4 to 4.8 nmol m-3 and 0.2 to 0.6 nmol m-3, respectively. The high abundance of K+and significant (P-value iron (FeTot: 60-1144 ng m-3), its fractional solubility (Fews %: 6.7 -26.5) and co-variability of Fews (%) with nss-SO42- suggests chemical processing of alluvial dust during atmospheric transport from the IGP. The characteristic mass ratios of nutrients (NInorg/NTot: 0.92 ± 0.13, NOrg/NTot: 0.21 ± 0.11, and PInorg/nss-Ca2+: 0.35 ± 0.23) in the atmospheric outflow from the IGP show striking similarity with those reported over the BoB. These results have implications to further increase in the atmospheric deposition of nutrients and their impact on biogeochemistry of surface Bay of Bengal.

  3. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    Science.gov (United States)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; Diskin, Glenn S.; Dickerson, Russell R.

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  4. Evolution of nutrient structure and phytoplankton composition in the Jiaozhou Bay ecosystem

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shu-jiang; JIAO Nian-zhi; WU Chang-wen; LIANG Bing; ZHANG Shu-yi

    2005-01-01

    The inventories of nutrients in the surface water and large phytoplankton( > 69 μm) were analyzed from the data set of JERS ecological database about a typical coastal waters, the Jiaozhou Bay, China, from 1960s for N, P and from 1980s for Si. By examining long-term changes of nutrient concentration, calculating stoichiometric balance, and comparing diatom composition, Si limitation of diatom production was found to be more possible. The possibility of Si limitation was from 37% in 1980s to 50% in 1990s. Jiaozhou Bay ecosystem is becoming serious eutrophication, with notable increase of NO2-N, NO3-N and NH4-N from 0.1417 μmol/L, 0.5414 μmol/L,1.7222 μmol/L in 1960s to 0.9551 μmol/L, 3.001 μmol/L, 8.0359 μmol/L in late 1990s respectively and prominent decrease of Si from 4.2614μmol/L in 1980s to 1.5861 μmol/L in late 1990s; the nutrient structure is controlled by nitrogen; the main limiting nutrient is probably silicon;because of the Si limitation the phytoplankton community structure has changed drastically.

  5. The impact of industrial anthropization on mosquito (Diptera, Culicidae) communities in mangrove areas of Guanabara Bay (Rio de Janeiro, Brazil).

    Science.gov (United States)

    de Souza, A S; Couri, M S; Florindo, L

    2012-02-01

    The effects of industrial anthropization on species composition and community diversity of Culicidae (Diptera) were studied in a mangrove area impacted by industrial activities as compared to a preserved area, both around Guanabara Bay in the state of Rio de Janeiro, Brazil. Diversity, equitability, and species richness in Culicidae community differed between the studied areas. Indicator species analysis and correspondence analysis were carried out and indicated that the Sabethini, especially Wyeomyia (Phoniomyia) theobaldi Lane, Wyeomyia (Phoniomyia) fuscipes (Edwards), and a non-identified species of Wyeomyia sp. were associated to the preserved area, whereas Aedes taeniorhynchus Wiedemann and Aedes scapularis (Rondani) to the impacted area.

  6. Simulating structural response to water impact

    OpenAIRE

    Campbell, James C; Vignjevic, Rade

    2012-01-01

    Structural response to water impact is important for several areas, including the aerospace and marine industries. Aircraft must be designed to cope with ditching and offshore structures are subject to extreme wave impact and green water loading. The goal is a reliable technique for predicting the structural response to extreme water loading. This is a complex problem involving the interaction of non-linear fluid behaviour (breaking waves, fluid impact) with non-linear structural behaviour (l...

  7. Impacts to Humboldt Bay NWR from forestry and dairy activities in the Salmon Creek Watershed

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The freshwater creeks, brackish water sloughs, saltwater marshes and mud flats found on the Humboldt Bay National Refuge provide habitats for at least 110 species of...

  8. Updated Fiscal Impact Analysis for the Naval Submarine Base, Kings Bay, Georgia. Technical Appendices

    Science.gov (United States)

    1986-12-01

    any person wishing to enter the labor force. Thus, the only existing labor supply is actually the inflow of spouses of inmigrants who wish to work...The existing labor supply for the Kings Bay expansion is calculated in the model by assuming that 60 percent of the spouses of inmigrants who wish to...work. The existing labor supply for the Kings Bay expansion is calculated in the model by assuming that 60 percent of the spouses of inmigrants from the

  9. External impacts of an intraurban air transportation system in the San Francisco Bay area

    Science.gov (United States)

    Lu, J. Y.; Gebman, J. R.; Kirkwood, T. F.; Mcclure, P. T.; Stucker, J. P.

    1972-01-01

    The effects are studied of an intraurban V/STOL commuter system on the economic, social, and physical environment of the San Francisco Bay Area. The Bay Area was chosen mainly for a case study; the real intent of the analysis is to develop methods by which the effects of such a system could be evaluated for any community. Aspects of the community life affected include: income and employment, benefits and costs, noise, air pollution, and road congestion.

  10. The unnatural history of Kāne‘ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts

    Science.gov (United States)

    Jokiel, Paul L.; Toonen, Robert J.

    2015-01-01

    Kāneʻohe Bay, which is located on the on the NE coast of Oʻahu, Hawaiʻi, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāneʻohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Loʻe (Coconut Island) in the southern region of the bay became home to the Hawaiʻi Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960’s the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of coral cover. The

  11. The unnatural history of Kāne'ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts.

    Science.gov (United States)

    Bahr, Keisha D; Jokiel, Paul L; Toonen, Robert J

    2015-01-01

    Kāne'ohe Bay, which is located on the on the NE coast of O'ahu, Hawai'i, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāne'ohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Lo'e (Coconut Island) in the southern region of the bay became home to the Hawai'i Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960's the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of coral cover. The reefs of K

  12. The unnatural history of Kāne‘ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts

    Directory of Open Access Journals (Sweden)

    Keisha D. Bahr

    2015-05-01

    Full Text Available Kāneʻohe Bay, which is located on the on the NE coast of Oʻahu, Hawaiʻi, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāneʻohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Loʻe (Coconut Island in the southern region of the bay became home to the Hawaiʻi Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960’s the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of

  13. Zonation and structuring factors of meiofauna communities in a tropical seagrass bed (Gazi Bay, Kenya)

    Science.gov (United States)

    De Troch, Marleen; Gurdebeke, Shirley; Fiers, Frank; Vincx, Magda

    2001-02-01

    This study deals with the relation between tropical meiofauna and environmental variables by comparing the 'benthic' (i.e. in the bare sediment adjacent to seagrass plants) and the 'epiphytic' (i.e. in samples including seagrass plants) meiofauna associated with five seagrass species from the high intertidal to the high subtidal zone in Gazi Bay (Kenya). Ordination and variance analysis revealed three distinct 'benthic' and two 'epiphytic' meiofauna assemblages. These assemblages corresponded entirely with those identified for the seagrass species: a high intertidal pioneer association ( Halophila ovalis/ Halodule wrightii), an intertidal climax assemblage ( Thalassia hemprichii) and a high subtidal pioneer association ( Halophila stipulacea/ Syringodium isoetifolium). These data support the hypothesis that meiofaunal communities correspond to the characteristic zonation of the seagrass vegetation in Gazi Bay. In beds of the pioneer seagrass species, the close relationship between sediment characteristics and both 'benthic' and 'epiphytic' meiofauna communities suggests that these pioneer communities were mainly driven by physical factors. The 'benthic' communities adjacent to the climax seagrass species T. hemprichii were more structured by biogenic factors, e.g. % TOM, chlorophyll a and c, fucoxanthin, habitat complexity and growth form of the seagrass species. For its associated 'epiphytic' meiofauna the latter conclusion was even more striking. These data corroborate the importance of physical factors in disturbed environments (intertidal zone, near pioneer seagrasses) and of biotic factors in more stable conditions (subtidal zone, near climax seagrasses).

  14. Community structure of shallow rocky shore fish in a tropical bay of the southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    Camilo Moitinho Ferreira

    2015-12-01

    Full Text Available Abstract Southwestern Atlantic Ocean rocky shores sustain important reef fish communities. However, those communities in tropical regions are not well understood, especially in Brazil. In this present article we assess community parameters of reef fishes such as composition, trophic organization and their relationships with physical and biological factors on four tropical rocky shores in Todos os Santos Bay, southwestern Atlantic. During six months, a total of 80 visual censuses were performed, in which 3,582 fish belonging to 76 species were recorded. Territorial herbivorous fish and turf algae were dominant at all the sites. The spatial variability of fish community structure was related to the benthic cover composition and depth. The high abundance of territorial herbivores and mobile invertebrate feeders could be associated with high levels of turf cover, low wave exposure and shallow waters. Moreover, this fact could be a consequence of the low density of roving herbivores and large carnivores probably due to the pressure of intense fishing activity. Thus complementary studies are needed to evaluate the actual conservation status of these rocky shore reefs, singularly located habitats connecting inner and outer reefs in Todos os Santos Bay.

  15. The impact of overlapping processes on rockfall hazard analysis - the Bolonia Bay study (southern Spain)

    Science.gov (United States)

    Fernandez-Steeger, T.; Grützner, C.; Reicherter, K.; Braun, A.; Höbig, N.

    2009-04-01

    For rockfall simulations, competitive case studies and data sets are important to develop and evaluate the models or software. Especially for empirical or data driven stochastic modelling the quality of the reference data sets has a major impact on model skills and knowledge discovery. Therefore, rockfalls in the Bolonia Bay close to Tarifa (Spain) were mapped. Here, the siliciclastic Miocene rocks (megaturbidites) are intensively joined and disaggregated by a perpendicular joint system. Although bedding supports stability as the dip is not directed towards the rock face, the deposits indicate a continuous process of material loss from the 80 m high cliff of the San Bartolome mountain front by single large rock falls. For more than 300 blocks data on size, shape, type of rock, and location were collected. The work concentrated on rockfall blocks with a volume of more than 2 m³ and up to 350 m³. Occasionally very long "runout" distances of up to 2 km have been observed. For all major source areas and deposits, runout analysis using empirical models and a numerical trajectorian model has been performed. The most empirical models are principally based on the relation between fall height and travel distance. Beside the "Fahrböschung" from Heim (1932) the "shadow angle" introduced by Evans and Hungr (1993) is most common today. However, studies from different sites show a wide variance of the angle relations (Dorren 2003, Corominas 1996). The reasons for that might be different environments and trigger mechanisms, or varying secondary effects such as post-depositional movement. Today, "semi" numerical approaches based on trajectorian models are quite common to evaluate the rockfall energy and the runout distance for protection measures and risk evaluations. The results of the models highly depend on the quality of the input parameters. One problem here might be that some of the parameters, especially the dynamic ones, are not easy to determine and the quality of the

  16. Quantifying the impact of watershed urbanization on a coral reef: Maunalua Bay, Hawaii

    Science.gov (United States)

    Wolanski, Eric; Martinez, Jonathan A.; Richmond, Robert H.

    2009-09-01

    Human activities in the watersheds surrounding Maunalua Bay, Oahu, Hawaii, have lead to the degradation of coastal coral reefs affecting populations of marine organisms of ecological, economic and cultural value. Urbanization, stream channelization, breaching of a peninsula, seawalls, and dredging on the east side of the bay have resulted in increased volumes and residence time of polluted runoff waters, eutrophication, trapping of terrigenous sediments, and the formation of a permanent nepheloid layer. The ecosystem collapse on the east side of the bay and the prevailing westward longshore current have resulted in the collapse of the coral and coralline algae population on the west side of the bay. In turn this has lead to a decrease in carbonate sediment production through bio-erosion as well as a disintegration of the dead coral and coralline algae, leading to sediment starvation and increased wave breaking on the coast and thus increased coastal erosion. The field data and resulting coral reef ecohydrology model presented in this paper demonstrate and quantify the importance of biophysical processes leading to coral reef degradation as the result of urbanization. Coral restoration in Maunalua Bay will require an integrated ecosystem approach.

  17. An Approach to Understanding Complex Socio-Economic Impacts and Responses to Climate Disruption in the Chesapeake Bay Region

    Science.gov (United States)

    Schaefer, R. K.; Nix, M.; Ihde, A. G.; Paxton, L. J.; Weiss, M.; Simpkins, S.; Fountain, G. H.; APl GAIA Team

    2011-12-01

    In this paper we describe the application of a proven methodology for modeling the complex social and economic interactions of a system under stress to the regional issues that are tied to global climate disruption. Under the auspices of the GAIA project (http://gaia.jhuapl.edu), we have investigated simulating the complex interplay between climate, politics, society, industry, and the environment in the Chesapeake Bay Watershed and associated geographic areas of Maryland, Virginia, and Pennsylvania. This Chesapeake Bay simulation draws on interrelated geophysical and climate models to support decision-making analysis about the Bay. In addition to physical models, however, human activity is also incorporated via input and output calculations. For example, policy implications are modeled in relation to business activities surrounding fishing, farming, industry and manufacturing, land development, and tourism. This approach fosters collaboration among subject matter experts to advance a more complete understanding of the regional impacts of climate change. Simulated interactive competition, in which teams of experts are assigned conflicting objectives in a controlled environment, allow for subject exploration which avoids trivial solutions that neglect the possible responses of affected parties. Results include improved planning, the anticipation of areas of conflict or high risk, and the increased likelihood of developing mutually acceptable solutions.

  18. Group structure of Guiana dolphins, Sotalia guianensis (Cetacea, Delphinidae in Ilha Grande Bay, Rio de Janeiro, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Rodrigo Tardin

    2013-04-01

    Full Text Available Cetaceans present a group structure of great complexity and display a wide behavioral plasticity. Many efforts have been made to understand the group structures of the various species, however, this type of information is still lacking for some species. Therefore, our objectives were to 1 characterize the structure of the Sotalia guianensis groups in Ilha Grande Bay, Rio de Janeiro, Brazil, and 2 investigate how both behavior and season influence the group structure of this population. This species is considered "data deficient" by the IUCN. We conducted 28 boat trips using group focal procedures, and a total of 1,314 groups were observed. Of these groups, 1,268 (94.4% contained calves, the largest percentage ever reported for the species. Groups with calves were larger than those without them, suggesting a strategy to protect these individuals with underdeveloped physiology. The mean group sizes reached 17.6 ± 18.3 individuals. Within these groups, we observed that both behavior (H = 112.5, d.f. = 2, P < 0.05 and season (number of simulations: 10,000; sample size of fall-winter = 544; sample size of spring-summer = 684; P < 0.05, demonstrated a statistically significant influence. The most common degree of cohesion was mixed, and cohesion also varied with behavior (χ2 = 10.1, P < 0.05 and season (χ2 = 31.0, P < 0.05. This paper contributes towards understanding the highly variable nature of S. guianensis group dynamics. These data may be important in understanding the structure of groups in a site that is being increasingly impacted by different human activities. Moreover, this area contains the largest aggregation ever observed for this species and may therefore represent an important source of genetic diversity for the species as a whole.

  19. Impact of horizontal resolution on prediction of tropical cyclones over Bay of Bengal using a regional weather prediction model

    Indian Academy of Sciences (India)

    M Mandal; U C Mohanty; K V J Potty; A Sarkar

    2003-03-01

    The present study is carried out to examine the performance of a regional atmospheric model in forecasting tropical cyclones over the Bay of Bengal and its sensitivity to horizontal resolution. Two cyclones, which formed over the Bay of Bengal during the years 1995 and 1997, are simulated using a regional weather prediction model with two horizontal resolutions of 165km and 55 km. The model is found to perform reasonably well towards simulation of the storms. The structure, intensity and track of the cyclones are found to be better simulated by finer resolution of the model as compared to the coarse resolution. Rainfall amount and its distribution are also found to be sensitive to the model horizontal resolution. Other important fields, viz., vertical velocity, horizontal divergence and horizontal moisture flux are also found to be sensitive to model horizontal resolution and are better simulated by the model with finer horizontal grids.

  20. Lummi Bay Marina, Whatcom County, Washington. Draft Detailed Project Report and Draft Environmental Impact Statement.

    Science.gov (United States)

    1983-12-01

    maritima’Grindelja in’regrlfolia Cotula coronopifolia Deschampsia cesp tosa (b) At circle in center: Grindelia integrifolia (inside) Salicornia virginica...species: Potentilla pacfica. Distichlis spicata Elymus mollis Grindelia integrifolia Solanum dulcamara (nightshade) Achillea millefolium (Yarrow) (5...plant species (i.e., Grindelia integrifolia, Cirsium spp., Achii a millefolium). -EIS-20 . . . . . . . . . . . . . . . . . LUMMI BAY VEGETATIVE SURVEY

  1. Decline of the Jakarta Bay molluscan fauna linked to human impact

    NARCIS (Netherlands)

    Meij, van der S.E.T.; Moolenbeek, R.G.; Hoeksema, B.W.

    2009-01-01

    In 1937/38 representative mollusc collections were made in Jakarta Bay (West Java, Indonesia). New data from here and the adjacent offshore Thousand Islands archipelago (Kepulauan Seribu) became available in 2005. Although collecting efforts and sampling methods differed, a comparison of the mollusc

  2. Phytoplankton community structure and environmental parameters in aquaculture areas of Daya Bay, South China Sea.

    Science.gov (United States)

    Wang, Zhaohui; Zhao, Jiangang; Zhang, Yujuan; Cao, Yu

    2009-01-01

    Environmental characteristics and phytoplankton community structure were investigated in two aquaculture areas in Dapeng Cove of Daya Bay, South China Sea, between April 2005 and June 2006. Phytoplankton abundance ranged between 5.0 and 8877.5 cells/mL, with an average of 751.8 cells/mL. The seasonal cycle of phytoplankton were demonstrated by frequent oscillations, with recurrent high abundances from late spring to autumn and a peak stage in late winter. Diatoms were the predominant phytoplankton group, accounting for 93.21% of the total abundance. The next most abundant group was the dinoflagellates, which made up only 1.24% of total abundance. High concentrations of Alexandrium tamarense (Lebour) Balech with a maximum of 603.0 cells/mL were firstly recorded in this area known for high rates of paralytic shellfish poisoning (PSP) contamination. Temperatures and salinities were within the suitable values for the growth of phytoplankton, and were important in phytoplankton seasonal fluctuations. The operation of the Daya Bay Nuclear Power Station (DNPS) exerts influences on the phytoplankton community and resulted in the high abundances of toxic dinoflagellate species during the winter months. Dissolved inorganic nitrogen (DIN) and dissolved silicate (DSi) were sufficient, and rarely limited for the growth of phytoplankton. Dissolved inorganic phosphorus (DIP) was the most necessary element for phytoplankton growth. The enriched environments accelerated the growth of small diatoms, and made for the shift in predominant species from large diatom Rhizosolenia spp. to chain-forming diatoms such as Skeletonema costatum, Pseudo-nitzschia spp. and Thalassiosira subtilis.

  3. Seismic velocity structure and seismotectonics of the eastern San Francisco Bay region, California

    Science.gov (United States)

    Hardebeck, J.L.; Michael, A.J.; Brocher, T.M.

    2007-01-01

    The Hayward Fault System is considered the most likely fault system in the San Francisco Bay Area, California, to produce a major earthquake in the next 30 years. To better understand this fault system, we use microseismicity to study its structure and kinematics. We present a new 3D seismic-velocity model for the eastern San Francisco Bay region, using microseismicity and controlled sources, which reveals a ???10% velocity contrast across the Hayward fault in the upper 10 km, with higher velocity in the Franciscan Complex to the west relative to the Great Valley Sequence to the east. This contrast is imaged more sharply in our localized model than in previous regional-scale models. Thick Cenozoic sedimentary basins, such as the Livermore basin, which may experience particularly strong shaking during an earthquake, are imaged in the model. The accurate earthquake locations and focal mechanisms obtained by using the 3D model allow us to study fault complexity and its implications for seismic hazard. The relocated hypocenters along the Hayward Fault in general are consistent with a near-vertical or steeply east-dipping fault zone. The southern Hayward fault merges smoothly with the Calaveras fault at depth, suggesting that large earthquakes may rupture across both faults. The use of the 3D velocity model reveals that most earthquakes along the Hayward fault have near-vertical strike-slip focal mechanisms, consistent with the large-scale orientation and sense of slip of the fault, with no evidence for zones of complex fracturing acting as barriers to earthquake rupture.

  4. Anthropogenic impacts on meiobenthic Ostracoda (Crustacea) in the moderately polluted Kasado Bay, Seto Inland Sea, Japan, over the past 70 years.

    Science.gov (United States)

    Irizuki, Toshiaki; Ito, Hisayo; Sako, Megumi; Yoshioka, Kaoru; Kawano, Shigenori; Nomura, Ritsuo; Tanaka, Yuichiro

    2015-02-15

    Two sediment cores were obtained from Kasado Bay, a moderate-polluted enclosed bay in Japan, to examine anthropogenic impacts on Ostracoda over the past ca. 70 years. We analyzed ostracode abundance and diversity, grain size, and CHN, and used (210)Pb and (137)Cs as the dating method. The present study showed that cross-plot comparisons of ostracode abundance and each environmental factor, based on sediment core data, could be used to identify ostracode species as indicators for anthropogenic influences. Ostracode abundance reflected mainly the changes that had occurred in total organic carbon content in sediments related to eutrophication, but heavy metal concentration did not directly influence several ostracode abundance in the bay. Environmental deterioration because of eutrophication started in the 1960s. The regulations regarding the chemical oxygen demand in waters introduced in the 1980s probably influence ostracode abundance for certain species in this period. Currently, Kasado Bay is not experiencing severe degradation.

  5. Causes and Consequences of Changes in Nutrient Structure in the Jiaozhou Bay

    Institute of Scientific and Technical Information of China (English)

    Shu-Jiang ZHAO; Nian-Zhi JIAO; Zhi-Liang SHEN; Yu-Lin WU

    2005-01-01

    Concentrations and ratios of nutrients in Jiaozhou Bay, China, have changed much in the past decades, with trends indicating an increase in nitrogen and a decrease in silicate. Statistical analysis has shown that the long-term variations of nutrients are associated with agricultural activities, precipitation, and anthropogenic factors. Stoichiometric calculations indicate that the nutrient structure has become more and more unbalanced. There has been almost no possibility for nitrogen limitation since the 1980s, the probability of P limitation has increased, and the probability of Si limitation has also increased markedly from the 1980s to the 1990s. As a consequence of changes in nutrient structure, a decrease in the abundance of net phytoplankton was evident, whereas total chlorophyll a levels have remained roughly unchanged at around 3.55 μg/L. Thus, it is likely that smaller species have taken the niche vacated by the larger species. Changes in phytoplankton size and species composition may ultimately lead to various functional and structural changes at the system level.

  6. Ancient blue oaks reveal human impact on San Francisco Bay salinity

    Science.gov (United States)

    Stahle, David W.; Therrell, Matthew D.; Cleaveland, Malcolm K.; Cayan, Daniel R.; Dettinger, Michael D.; Knowles, Noah

    2001-01-01

    San Francisco Bay is one of the most important estuaries on the west coast of the Americas. Its water quality is controlled primarily by streamflow from the Sacramento and San Joaquin rivers. In fact, freshwater inflow from the Sacramento-San Joaquin Delta explains 86% of the salinity variability at the mouth of the San Francisco Bay estuary [Peterson et al., 1989]. The massive diversion of streamflow by the California State Water Project and the Central Valley Project, part of the largest manmade water control system on Earth [Reisner, 1988], has raised salinity in the estuary on daily, seasonal, and annual timescales [Nichols et al., 1986; Peterson et al., 1989].

  7. Waveform tomography of crustal structure in the south San Francisco Bay region

    Science.gov (United States)

    Pollitz, F.F.; Fletcher, J.P.

    2005-01-01

    We utilize a scattering-based seismic tomography technique to constrain crustal tructure around the southern San Francisco Bay region (SFBR). This technique is based on coupled traveling wave scattering theory, which has usually been applied to the interpretation of surface waves in large regional-scale studies. Using fully three-dimensional kernels, this technique is here applied to observed P, S, and surface waves of intermediate period (3-4 s dominant period) observed following eight selected regional events. We use a total of 73 seismograms recorded by a U.S. Geological Survey short-period seismic array in the western Santa Clara Valley, the Berkeley Digital Seismic Network, and the Northern California Seismic Network. Modifications of observed waveforms due to scattering from crustal structure include (positive or negative) amplification, delay, and generation of coda waves. The derived crustal structure explains many of the observed signals which cannot be explained with a simple layered structure. There is sufficient sensitivity to both deep and shallow crustal structure that even with the few sources employed in the present study, we obtain shallow velocity structure which is reasonably consistent with previous P wave tomography results. We find a depth-dependent lateral velocity contrast across the San Andreas fault (SAF), with higher velocities southwest of the SAF in the shallow crust and higher velocities northeast of the SAF in the midcrust. The method does not have the resolution to identify very slow sediment velocities in the upper approximately 3 km since the tomographic models are smooth at a vertical scale of about 5 km. Copyright 2005 by the American Geophysical Union.

  8. Observations of pockmark flow structure in Belfast Bay, Maine, Part 1: current-induced mixing

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Irish, James D.; Brothers, Laura L.

    2017-01-01

    Field observations of current profiles and temperature, salinity, and density structure were used to examine vertical mixing within two pockmarks in Belfast Bay, Maine. The first is located in 21 m water depth (sea level to rim), nearly circular in shape with a 45 m rim diameter and 12 m rim-to-bottom relief. The second is located in 25 m water depth, more elongated in shape with an approximately 80 m (36 m) major (minor) axis length at the rim, and 17 m relief. Hourly averaged current profiles were acquired from bottom-mounted acoustic Doppler current profilers deployed on the rim and center of each pockmark over successive 42 h periods in July 2011. Conductivity–temperature–depth casts at the rim and center of each pockmark show warmer, fresher water in the upper water column, evidence of both active and fossil thermocline structure 5–8 m above the rim, and well-mixed water below the rim to the bottom. Vertical velocities show up- and down-welling events that extend into the depths of each pockmark. An observed temperature change at both the rim and center occurs coincident with an overturning event below the rim, and suggests active mixing of the water column into the depths of each pockmark. Vertical profiles of horizontal velocities show depth variation at both the center and rim consistent with turbulent logarithmic current boundary layers, and suggest that form drag may possibly be influencing the local flow regime. While resource limitations prevented observation of the current structure and water properties at a control site, the acquired data suggest that active mixing and overturning within the sampled pockmarks occur under typical benign conditions, and that current flows are influenced by upstream bathymetric irregularities induced by distant pockmarks.

  9. Observations of pockmark flow structure in Belfast Bay, Maine, Part 1: current-induced mixing

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Irish, James D.; Brothers, Laura L.

    2017-02-01

    Field observations of current profiles and temperature, salinity, and density structure were used to examine vertical mixing within two pockmarks in Belfast Bay, Maine. The first is located in 21 m water depth (sea level to rim), nearly circular in shape with a 45 m rim diameter and 12 m rim-to-bottom relief. The second is located in 25 m water depth, more elongated in shape with an approximately 80 m (36 m) major (minor) axis length at the rim, and 17 m relief. Hourly averaged current profiles were acquired from bottom-mounted acoustic Doppler current profilers deployed on the rim and center of each pockmark over successive 42 h periods in July 2011. Conductivity-temperature-depth casts at the rim and center of each pockmark show warmer, fresher water in the upper water column, evidence of both active and fossil thermocline structure 5-8 m above the rim, and well-mixed water below the rim to the bottom. Vertical velocities show up- and down-welling events that extend into the depths of each pockmark. An observed temperature change at both the rim and center occurs coincident with an overturning event below the rim, and suggests active mixing of the water column into the depths of each pockmark. Vertical profiles of horizontal velocities show depth variation at both the center and rim consistent with turbulent logarithmic current boundary layers, and suggest that form drag may possibly be influencing the local flow regime. While resource limitations prevented observation of the current structure and water properties at a control site, the acquired data suggest that active mixing and overturning within the sampled pockmarks occur under typical benign conditions, and that current flows are influenced by upstream bathymetric irregularities induced by distant pockmarks.

  10. Observations of pockmark flow structure in Belfast Bay, Maine, Part 1: current-induced mixing

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Irish, James D.; Brothers, Laura L.

    2016-10-01

    Field observations of current profiles and temperature, salinity, and density structure were used to examine vertical mixing within two pockmarks in Belfast Bay, Maine. The first is located in 21 m water depth (sea level to rim), nearly circular in shape with a 45 m rim diameter and 12 m rim-to-bottom relief. The second is located in 25 m water depth, more elongated in shape with an approximately 80 m (36 m) major (minor) axis length at the rim, and 17 m relief. Hourly averaged current profiles were acquired from bottom-mounted acoustic Doppler current profilers deployed on the rim and center of each pockmark over successive 42 h periods in July 2011. Conductivity-temperature-depth casts at the rim and center of each pockmark show warmer, fresher water in the upper water column, evidence of both active and fossil thermocline structure 5-8 m above the rim, and well-mixed water below the rim to the bottom. Vertical velocities show up- and down-welling events that extend into the depths of each pockmark. An observed temperature change at both the rim and center occurs coincident with an overturning event below the rim, and suggests active mixing of the water column into the depths of each pockmark. Vertical profiles of horizontal velocities show depth variation at both the center and rim consistent with turbulent logarithmic current boundary layers, and suggest that form drag may possibly be influencing the local flow regime. While resource limitations prevented observation of the current structure and water properties at a control site, the acquired data suggest that active mixing and overturning within the sampled pockmarks occur under typical benign conditions, and that current flows are influenced by upstream bathymetric irregularities induced by distant pockmarks.

  11. Observations of pockmark flow structure in Belfast Bay, Maine, Part 2: evidence for cavity flow

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-01-01

    Pockmark flow circulation patterns were investigated through current measurements along the rim and center of two pockmarks in Belfast Bay, Maine. Observed time-varying current profiles have a complex vertical and directional structure that rotates significantly with depth and is strongly dependent on the phase of the tide. Observations of the vertical profiles of horizontal velocities in relation to relative geometric parameters of the pockmark are consistent with circulation patterns described qualitatively by cavity flow models (Ashcroft and Zhang 2005). The time-mean behavior of the shear layer is typically used to characterize cavity flow, and was estimated using vorticity thickness to quantify the growth rate of the shear layer horizontally across the pockmark. Estimated positive vorticity thickness spreading rates are consistent with cavity flow predictions, and occur at largely different rates between the two pockmarks. Previously modeled flow (Brothers et al. 2011) and laboratory measurements (Pau et al. 2014) over pockmarks of similar geometry to those examined herein are also qualitatively consistent with cavity flow circulation, suggesting that cavity flow may be a good first-order flow model for pockmarks in general.

  12. Observations of pockmark flow structure in Belfast Bay, Maine, Part 2: evidence for cavity flow

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-02-01

    Pockmark flow circulation patterns were investigated through current measurements along the rim and center of two pockmarks in Belfast Bay, Maine. Observed time-varying current profiles have a complex vertical and directional structure that rotates significantly with depth and is strongly dependent on the phase of the tide. Observations of the vertical profiles of horizontal velocities in relation to relative geometric parameters of the pockmark are consistent with circulation patterns described qualitatively by cavity flow models (Ashcroft and Zhang 2005). The time-mean behavior of the shear layer is typically used to characterize cavity flow, and was estimated using vorticity thickness to quantify the growth rate of the shear layer horizontally across the pockmark. Estimated positive vorticity thickness spreading rates are consistent with cavity flow predictions, and occur at largely different rates between the two pockmarks. Previously modeled flow (Brothers et al. 2011) and laboratory measurements (Pau et al. 2014) over pockmarks of similar geometry to those examined herein are also qualitatively consistent with cavity flow circulation, suggesting that cavity flow may be a good first-order flow model for pockmarks in general.

  13. Impact of Human Activities on Depositional Process of Tidal Flat in Quanzhou Bay of China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    As a very important component of a coastal system, tidal flats come to be a focus of the studies on land-ocean interaction in the coastal zone because those areas are subjected to intense human activities and are highly sensitive to the global change. The Quanzhou Bay, located along the middle part of Fujian coast of China, covers about 136.4km2, and the area of coastal wetland in the entire bay from intertidal to subtidal with 6m of water depth accounts for 96% of the total area. Seven short cores were collected and divided in situ with the interval of 5cm on the coastal wetlands of Quanzhou Bay on April 19, 2006. The sediment samples were scattered and the grain sizes were measured by using Mastersizer 2000. Human beings' activities on tidal flat have disturbed the vertical distribution of sediments in stratigraphic sequence and accelerated the sedimentation rates. Grain size analysis results show that the grain size diameters increase and sediment becomes worse sorted towards the sea under the strong human disturbance; Spartina alterniflora can play a role of trapping the fine sediment; but near the bank, the sediment becomes coarse and there are two peak values on frequency curve influenced by the sandpile. The trough formed by human activities along the coastline changes the transport path of water and suspended sediment. The sediments are transported through the trough and deposit in it during the flood; the ebb flow is retarded by the flow output through the adjacent trough, and the deposited sediment can not be re-suspended; then, the sedimentation rate increases. In situ observation show that the sedimentation rate is about 8-10 cm/yr.

  14. Atmospheric outflow of nutrients to the Bay of Bengal: Impact of anthropogenic sources..

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, B.; Sarin, M.M.; Sarma, V.V.S.S.

    In addition, statistical tests were performed to ascertain the significant differences in the atmospheric abundances of nutrients and their molar ratios between the two sampling periods (viz., December’08 – January’09, collected from the MABL of Bay...-3. However, the molar mass ratio of NOrg/NTot during November’09 – March’10 averages ~ 0.25 ± 0.10 (range: 0.12 to 0.40). Similar to the contribution of NInorg/NTot, the fractional abundance ratio of NOrg to NTot in fine mode aerosols also shows...

  15. The Impact of Sound Structure on Morphology

    DEFF Research Database (Denmark)

    Laaha, Sabine; Kjærbæk, Laila; Basbøll, Hans

    2011-01-01

    This study examines the impact of sound structure on children’s acquisition of noun plural morphology, focussing on stem change. For this purpose, a threelevel classification of stem change properties according to sound structure is presented, with increasing opacity of the plural stem: no change...

  16. Trace/heavy metal pollution monitoring in estuary and coastal area of Bay of Bengal, Bangladesh and implicated impacts.

    Science.gov (United States)

    Kibria, Golam; Hossain, Md Maruf; Mallick, Debbrota; Lau, T C; Wu, Rudolf

    2016-04-15

    Using artificial mussels (AMs), this study reports and compares time-integrated level of eleven trace metals (Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, U, Zn) in Karnafuli River estuary and coastal area of the Bay of Bengal, Bangladesh. Through this study, "hot spots" of metal pollution were identified. The results may demonstrate that the Karnafuli Estuary, and adjacent coastal area of Chittagong, Bangladesh are highly polluted by high risk metals (cadmium, chromium, copper, mercury, nickel, lead, uranium). Agricultural, domestic and industrial wastes directly discharged into the waterways have been identified as the main causes of metal pollution in Chittagong, Bangladesh. The high level of metal pollution identified may impact on local water quality, and seafood catch, livelihoods of people and public health resulting from seafood consumption. There is a need for regular monitoring to ascertain that local water quality with respect to metal levels are within acceptable levels to safeguards both environmental health and public health.

  17. Trophic structure of the fouling community in Odessa Bay (Black Sea

    Directory of Open Access Journals (Sweden)

    A. Y. Varigin

    2016-06-01

    Full Text Available The trophic structure of the coastal fouling community of Odessa Bay (Black Sea, which was composed of 10 species of macrophytes, 57 invertebrate species and 4 species of fish, was determined. The basic trophic relationship between organisms composing the community is shown. A minimization of interspecific trophic competition within the community is noted. The main sources of food material entering the fouling community were determined. We show that a significant proportion of food in the form of detritus, dissolved organic matter and small planktonic organisms enters the community from the water column. Filtration and pumping activity of sestonophage-organisms, particularly mussels, helps to attract food material to the community. Primary producers of the community are macrophytes and microphytes, which develop on account of their photosynthetic activity and ensure the provision of food to herbivores. The trophic group of detritophages consumes different fractions of the detritus which accumulates in the byssus threads of bivalve molluscs. In this context, mussel druses act as sediment traps, collecting detritus. Numerous polyphages, which are essentially omnivores and do not usually lack food material, were noted in the community. A small group of carnivorous invertebrates, whose representatives actively attack small animals, was identified. The abundance of these species in the community was about 1%, and their biomass less than 0.6%. Fish living in macrophyte weeds are the consumers in the community. We determined that the highest relative abundance (over 36% in the fouling community was reached by sestonophages and polyphages. We found that the undisputed leader in the relative biomass (over 97% in the fouling community ofOdessaBaywas the sestonophages (mainly composed of mussels. We determined that the trophic structure index of the community was 0.94, which confirms the significant dominance in biomass of bivalves over other species in

  18. [Impact of typhoon "Fung-wong" on the distribution patterns of heavy metals in the Quanzhou Bay].

    Science.gov (United States)

    Li, Yun-Hai; Chen, Jian; Chen, Jian-Ning; Huang, Cai-Bin; Wang, Ai-Jun; Li, Dong-Yi

    2010-06-01

    Based on the inductively coupled plasma mass spectroscopy (ICP-MS) data of concentrations of 7 heavy metals (including Cr, Ni, Cu, Zn, Cd, Pb and As) in suspended particles and surface sediments samples collected at 6 and 1 13-hours-mooring stations, respectively, in Quanzhou Bay 4 days after the landing of typhoon "Fung-wong". The average contents of Cr, Ni, Cu, Zn, As, and Cd are 60.4, 50.3, 26.5, 101.7, 3.36, 40.0 and 0.180 microg/g, respectively, in the surface sediments, and are 1.108-7.408, 0.476-3. 394, 0.809-5.046, 3.190-19.337, 0.087-0.595, 2.621-10.073 microg/L and 4.160-50.828 ng/L, respectively, in different stations in the suspended particles. The contents and distribution patterns of 7 heavy metals during a tidal cycle were significantly changed after typhoon "Fung-wong" by contrasting with that in same stations and tidal time at an ordinary situation. The contents of heavy metals, besides Ni, evidently decreased but the distribution patterns were similar with that in an ordinary condition with relatively large grads after typhoon "Fung-wong" in the surface sediments at station Q4. While in the suspended particles, the contents of heavy metals were evidently increased with the distribution patterns varied obviously and differently due to their geographical position after typhoon "Fung-wong". These impacts of typhoon "Fung-wong" to the contents and distribution patterns of heavy metals could be attribute to the "second contamination" and the increased supply of particles materials from continent during the typhoon process. The results of this study provide a reference to accurate assessing and scientific governing the heavy metals' contamination, and provide a directly support to evaluating the integrated impacts of typhoon process on the contamination of heavy metals in the Quanzhou Bay.

  19. Phenotypic impact of genomic structural variation

    DEFF Research Database (Denmark)

    Weischenfeldt, Joachim; Symmons, Orsolya; Spitz, François;

    2013-01-01

    Genomic structural variants have long been implicated in phenotypic diversity and human disease, but dissecting the mechanisms by which they exert their functional impact has proven elusive. Recently however, developments in high-throughput DNA sequencing and chromosomal engineering technology have...... facilitated the analysis of structural variants in human populations and model systems in unprecedented detail. In this Review, we describe how structural variants can affect molecular and cellular processes, leading to complex organismal phenotypes, including human disease. We further present advances...

  20. Engineering technologies for steel structure applied to Trans-Tokyo bay highway project; Tokyowan odan doro ni okeru kokozo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Furumuro, K.; Kobayashi, T.; Kanda, K. [Kawasaki Steel Corp., Tokyo (Japan)

    1996-03-01

    The Trans-Tokyo Bay Highway is a 15.1 km toll road that spans the Tokyo Bay from Kawasaki City in Kanagawa Prefecture to Kisarazu City in Chiba Prefecture by a bridge, an undersea shield tunnel, and two man-made islands. Many new technologies and methods were introduced to construct a large-scale structure safely, rationally, and in a short time on the weak ground under the depth of water in a seismic region such as Tokyo Bay. Kawasaki Steel participated in this project in: (1) development and construction of a revetment structure to which the technology of an oil drilling jacket was applied, (2) design and construction of a large-sized bridge with long-span and multi-span continuous girders on the sea, and (3) design and installation of a mud water treatment module for the shield tunnel constructed on the sea. As a result, the bearing-capacity measurement technology based on the dynamic method of a large diameter steel pipe pile was developed in item (1). The long-term corrosion-proof method using titanium clad steel was developed in item (2), and the way to construct the treatment facilities of approximately 5100 tons in item (3). 3 refs., 12 figs.

  1. [Hydrological and edaphic structure of an oyster-farming site: Duna Blanca (Bay of Dakhla, south Morocco)].

    Science.gov (United States)

    Zidane, H; Orbi, A; Mouradi, A; Zidane, F; Blais, J F

    2008-09-01

    Morocco shelters lagoons, estuaries and bays along its paralic coasts which are among the most productive in the world. The Bay of Dakhla is the longest and the most important site in Morocco due to its halieutic richness. In fact, this bay is an ecosystem with great potential in terms of aquaculture, mainly shellfish farming, and shelters favorable zones for tapiculture, mytiliculture and ostreiculture, in accordance with ecological planning. A hydrological study (temperature, salinity, chlorophyll "a", suspended matter and organic matter) was conducted on a breeding project of the cupped oyster (Crassostrea gigas) installed on the Duna Blanca site since April 2003. A seasonal follow-up of sediment structure was carried out involving granulometric and metallic studies. The hydrological sampling was performed monthly on the surface and at the bottom, during spring tides, low tide and high tide. The results confirmed that the site encompasses a wealth of nutritive elements and a significant chlorophyll-rich biomass. A gradient of hypersalinity is well correlated with seasonal variation of the temperature. The sedimentary structure ranges from muddy-sandy to sandy type. The metal concentrations in the sediments never exceeded the toxicity thresholds. However, the site's production potential cannot be limitless and could be affected by the extension and installation of new conchylaceous farms.

  2. Characterizing exposure and potential impacts of contaminants on seabirds nesting at South San Diego Bay Unit of the San Diego National Wildlife Refuge (Salt Works, San Diego Bay)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In 2005, a two-year USFWS study (1261-1N74) was initiated to characterize contaminant exposure by seabirds that nest in colonies at the South Bay Salt Works, within...

  3. Drastic and synchronous changes in megabenthic community structure concurrent with environmental variations in a eutrophic coastal bay

    Science.gov (United States)

    Kodama, Keita; Oyama, Masaaki; Lee, Jeong-hoon; Kume, Gen; Yamaguchi, Atsuko; Shibata, Yasuyuki; Shiraishi, Hiroaki; Morita, Masatoshi; Shimizu, Makoto; Horiguchi, Toshihiro

    2010-10-01

    This study demonstrated long-term changes in the stock size and species composition of the megabenthic community, including both vertebrates and invertebrates, in Tokyo Bay, Japan, a semi-enclosed coastal area in which the ecosystem has been affected by both natural and anthropogenic factors. We conducted fisheries-independent trawl surveys over a total of 26 yr (1977-1995 and 2003-2009) to collect megabenthos from the entire bay. We also obtained environmental data for the bay from published records to investigate relationships between biota and environment. Abundance- and biomass-based densities of the megabenthos increased until the late 1980s, followed by an abrupt decline, which we attribute to changes in the densities of small to mid-sized dominant species. In the 2000s, although the abundance-based density remained low, biomass-based density increased substantially due to an increase in the numbers of large fishes. Cluster analysis divided the survey period into six groups showing characteristic species compositions and densities. Stepwise multivariate discriminant analysis (SMDA) revealed that changes in water temperature, dissolved oxygen concentration, precipitation, and copepod density were accompanied by simultaneous changes in the megabenthic community. The SMDA cross-validation test indicated that the percentage of incorrect classifications of the model ranged from 14.3% to 66.7%, implying that factors not incorporated in the model, such as fisheries pressure, might affect the changes in the megabenthic community structure. Our results suggest that major shifts have occurred in the megabenthic community structure in Tokyo Bay, and that both natural and anthropogenic factors can trigger these shifts in the system.

  4. The bioeconomic impact of different management regulations on the Chesapeake Bay blue crab fishery

    Science.gov (United States)

    Bunnell, David B.; Lipton, Douglas W.; Miller, Thomas J.

    2010-01-01

    The harvest of blue crabs Callinectes sapidus in Chesapeake Bay declined 46% between 1993 and 2001 and remained low through 2008. Because the total market value of this fishery has declined by an average of US $ 3.3 million per year since 1993, the commercial fishery has been challenged to maintain profitability. We developed a bioeconomic simulation model of the Chesapeake Bay blue crab fishery to aid managers in determining which regulations will maximize revenues while ensuring a sustainable harvest. We compared 15 different management scenarios, including those implemented by Maryland and Virginia between 2007 and 2009, that sought to reduce female crab harvest and nine others that used seasonal closures, different size regulations, or the elimination of fishing for specific market categories. Six scenarios produced the highest revenues: the 2008 and 2009 Maryland regulations, spring and fall closures for female blue crabs, and 152- and 165-mm maximum size limits for females. Our most important finding was that for each state the 2008 and 2009 scenarios that implemented early closures of the female crab fishery produced higher revenues than the 2007 scenario, in which no early female closures were implemented. We conclude that the use of maximum size limits for female crabs would not be feasible despite their potentially high revenue, given the likelihood that the soft-shell and peeler fisheries cannot be expanded beyond their current capacity and the potentially high mortality rate for culled individuals that are the incorrect size. Our model results support the current use of seasonal closures for females, which permit relatively high exploitation of males and soft-shell and peeler blue crabs (which have high prices) while keeping the female crab harvest sustainable. Further, our bioeconomic model allows for the inclusion of an economic viewpoint along with biological data when target reference points are set by managers.

  5. Crustal structure of the coastal and marine San Francisco Bay region, California

    Science.gov (United States)

    Parsons, Tom

    2002-01-01

    As of the time of this writing, the San Francisco Bay region is home to about 6.8 million people, ranking fifth among population centers in the United States. Most of these people live on the coastal lands along San Francisco Bay, the Sacramento River delta, and the Pacific coast. The region straddles the tectonic boundary between the Pacific and North American Plates and is crossed by several strands of the San Andreas Fault system. These faults, which are stressed by about 4 cm of relative plate motion each year, pose an obvious seismic hazard.

  6. Impact of Shrimp Farm Effluent on Water Quality in Coastal Areas of the World Heritage-Listed Ha Long Bay

    Directory of Open Access Journals (Sweden)

    Thuyet D. Bui

    2012-01-01

    Full Text Available Problem statement: Shrimp farming has rapidly developed in coastal areas of the World Heritage-listed Ha Long Bay since the last decade. Effluent discharged from shrimp farms with high levels of nutrient waste may cause eutrophication in receiving waterways. Therefore, assessing water quality at tidal creeks receiving shrimp farm effluent in coastal areas of Ha Long Bay supports environmental protection and decision making for sustainable development of the region. Approach: Water samples were collected at 3 different locations for spatial assessment: inside sections of creeks directly receiving farm effluent (IEC, from main creeks adjacent to points of effluent discharge outside concentrated shrimp farms (OEC and a few kilometers away from shrimp farm (ASF. Samples were taken on 3 occasions for temporal assessment. Parameters related to nutrient waste from shrimp farms, including: Total Ammonia Nitrogen (TAN, Nitrite-Nitrogen (NO2-N, Nitrate-Nitrogen (NO3-N, Total Phosphorus (TP, Dissolved Orthophosphate (PO4-P, Biochemical Oxygen Demand (BOD, Chemical Oxygen Demand (COD, Total Suspended Solid (TSS, Chlorophyll-a (Chl-a, Temperature, Salinity, pH and Dissolved Oxygen (DO were determined using standard methods. Results: There were statistically significant differences in the concentrations of TAN, NO2-N, NO3-N, TP, PO4-P, BOD, COD and Chl-a among IEC, OEC, ASF and the levels of these parameters increased after shrimp crops, especially after the main shrimp crop of the season in North Vietnam. The concentrations of TAN, NO3-N, TP, BOD, COD, Chl-a, TSS at IEC sites were higher than recommended for protecting aquatic ecosystems. Principal Component Analysis (PCA efficiently summarized patterns of co-variation in water quality parameters among locations and study times. Conclusion/Recommendations: The findings of this study indicate that greater awareness of the environmental impacts of shrimp farms is required if this industry is to be sustainable

  7. Structural Health Monitoring for Impact Damage in Composite Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis P.; Raymond Bond (Purdue); Doug Adams (Purdue)

    2014-08-01

    Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This work seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the

  8. A chemostratigraphic method to determine the end of impact-related sedimentation at marine-target impact craters (Chesapeake Bay, Lockne, Tvären)

    Science.gov (United States)

    Ormö, Jens; Hill, Andrew C.; Self-Trail, Jean M.

    2010-01-01

    To better understand the impact cratering process and its environmental consequences at the local to global scale, it is important to know when in the geological record of an impact crater the impact-related processes cease. In many instances, this occurs with the end of early crater modification, leaving an obvious sedimentological boundary between impactites and secular sediments. However, in marine-target craters the transition from early crater collapse (i.e., water resurge) to postimpact sedimentation can appear gradual. With the a priori assumption that the reworked target materials of the resurge deposits have a different chemical composition to the secular sediments we use chemostratigraphy (δ13Ccarb, %Corg, major elements) of sediments from the Chesapeake Bay, Lockne, and Tvären craters, to define this boundary. We show that the end of impact-related sedimentation in these cases is fairly rapid, and does not necessarily coincide with a visual boundary (e.g., grain size shift). Therefore, in some cases, the boundary is more precisely determined by chemostratigraphy, especially carbonate carbon isotope variations, rather than by visual inspection. It is also shown how chemostratigraphy can confirm the age of marine-target craters that were previously determined by biostratigraphy; by comparing postimpact carbon isotope trends with established regional trends.

  9. Chesapeake Bay: Introduction to an Ecosystem.

    Science.gov (United States)

    Environmental Protection Agency, Washington, DC.

    The Chesapeake Bay is the largest estuary in the contiguous United States. The Bay and its tidal tributaries make up the Chesapeake Bay ecosystem. This document, which focuses of various aspects of this ecosystem, is divided into four major parts. The first part traces the geologic history of the Bay, describes the overall physical structure of…

  10. Sound speed structure in the Arabian Sea and the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Navelkar, G.S.; Murty, T.V.R.; Somayajulu, Y.K.; Murty, C.S.

    Sound speed computed from annual mean temperature and salinity data of Levitus reveals that spatial variation in the Arabian Sea is greater than that in the Bay of Bengal. Maximum spatial variation of sound speed in the Arabian Sea noticed between...

  11. Structure and growth of scales of yellow perch of Green Bay

    Science.gov (United States)

    Joeris, Leonard S.

    1957-01-01

    The appearance of the scales of yellow perch differs with the location on the fish's body. Comparison of scales of Green Bay perch taken above and below the lateral line reveals the former to have more sharply defined circuli and to exhibit fewer false annuli and less of the shading that impedes accurate assessment of age.

  12. Impacts of sea-level rise on the Moroccan coastal zone: Quantifying coastal erosion and flooding in the Tangier Bay

    Science.gov (United States)

    Snoussi, Maria; Ouchani, Tachfine; Khouakhi, Abdou; Niang-Diop, Isabelle

    2009-06-01

    As part of a broad assessment of climate change impacts in Morocco, an assessment of vulnerability and adaptation of coastal zones to sea-level rise was conducted. Tangier Bay which is the most important socio-economic pole in Northern Morocco represents one of the cases studies. Using a GIS-based inundation analysis and an erosion modelling approach, the potential physical vulnerability to accelerated sea-level rise was investigated, and the most vulnerable socio-economic sectors were assessed. Results indicate that 10% and 24% of the area will be at risk of flooding respectively for minimum (4 m) and maximum (11 m) inundation levels. The most severely impacted sectors are expected to be the coastal defences and the port, the urban area, tourist coastal infrastructures, the railway, and the industrial area. Shoreline erosion would affect nearly 20% and 45% of the total beach areas respectively in 2050 and 2100. Potential response strategies and adaptation options identified include: sand dune fixation, beach nourishment and building of seawalls to protect the urban and industrial areas of high value. It was also recommended that an Integrated Coastal Zone Management Plan for the region, including upgrading awareness, building regulation and urban growth planning should be the most appropriate tool to ensure a long-term sustainable development, while addressing the vulnerability of the coast to future sea-level rise.

  13. Down-core changes in molluscan death assemblages at Panzano Bay, an impacted area in the northern Adriatic Sea

    Science.gov (United States)

    Haselmair, Alexandra; Gallmetzer, Ivo; Stachowitsch, Michael; Tomasovych, Adam; Zuschin, Martin

    2016-04-01

    We use a historical ecology approach to shed light on the environmental history of the northern Adriatic Sea over the last hundreds to thousands of years. We focus on down-core changes in molluscan death assemblages, which serve as proxies for ecological shifts over time. The northern Adriatic Sea is particularly suited to study ecosystem modification under human pressure because it is among the most degraded marine ecosystems worldwide. We chose a sampling station in Panzano Bay, close the Isonzo River mouth and not far from the major industrial harbours of Trieste (Italy) and Koper (Slovenia), and traced down-core changes in molluscan community structure in correlation to major anthropogenic impacts that occurred here during the last centuries. Five sediment cores (1.5 m in length and diameters of 90 and 160 mm) were taken at a water depth of 12 m. We analysed grain size composition, the concentration of heavy metals and organic pollutants, and radiometrically dated the sediment using 210Pb. Furthermore, we dated shells of the abundant bivalve species Corbula gibba using 14C calibrated amino acid-racemisation (AAR). The whole molluscan community in the cores was analysed for species composition, abundance, taxonomic similarity, evidence for ecological interactions (i.e., frequencies of drilling predation) and taphonomic conditions of shells. The granulometric analysis shows that silt and clay dominate equally throughout the cores. Radiometric sediment dating revealed an average sedimentation rate of 2.5 mm/yr during the last 120 years. Shell dating points to a comparable overall core age, with only a few shell specimens being older than 500 years in the deepest core layer. In total, 10,452 mollusc individuals were analysed and 104 species identified. The most abundant bivalve species are Kurtiella bidentata, Corbula gibba and Abra nitida. Turritella communis and Nassarius pygmaeus are the most frequent gastropod species. Down-core changes in species composition

  14. Geomorphic change in Dingzi Bay, East China since the 1950s: impacts of human activity and fluvial input

    Science.gov (United States)

    Tian, Qing; Wang, Qing; Liu, Yalong

    2016-11-01

    This study examines the geomorphic evolution of Dingzi Bay, East China in response to human activity and variations in fluvial input since the 1950s. The analysis is based on data from multiple mathematical methods, along with information obtained from Remote Sensing, Geographic Information System and Global Position System technology. The results show that the annual runoff and sediment load discharged into Dingzi Bay display significant decreasing trends overall, and marked downward steps were observed in 1966 and 1980. Around 60%-80% of the decline is attributed to decreasing precipitation in the Wulong River Basin. The landform types in Dingzi Bay have changed significantly since the 1950s, especially over the period between 1981 and 1995. Large areas of tidal flats, swamp, salt fields, and paddy fields have been reclaimed, and aquaculture ponds have been constructed. Consequently, the patterns of erosion and deposition in the bay have changed substantially. Despite a reduction in sediment input of 65.68% after 1966, low rates of sediment deposition continued in the bay. However, deposition rates changed significantly after 1981 owing to large-scale development in the bay, with a net depositional area approximately 10 times larger than that during 1961-1981. This geomorphic evolution stabilized following the termination of large-scale human activity in the bay after 1995. Overall, Dingzi Bay has shown a tendency towards silting-up during 1952-2010, with the bay head migrating seaward, the number of channels in the tidal creek system decreasing, and the tidal inlet becoming narrower and shorter. In conclusion, largescale development and human activity in Dingzi Bay have controlled the geomorphic evolution of the bay since the 1950s.

  15. A study of the anticipated impacts on Canada from the development of liquefied natural gas terminals on Passamaquoddy Bay : final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-10-15

    This study provided a qualitative assessment of the potential impacts and risks associated with the development of liquefied natural gas (LNG) terminals on the United States side of Pasamaquoddy Bay. The report included an assessment of environmental impacts, marine and navigational safety impacts, and socio-economic impacts as a result of the terminal. The report also investigated the potential impacts on coastal ecosystems and wetlands, as well as potential impacts on land-based flora and fauna. Impacts from marine traffic through Canadian waters were considered. Three worst-case risk scenarios were used as the basis for determining potential environmental and socio-economic impacts. Potential effects and policy considerations associated with the construction of LNG terminals in the region were discussed. The study considered 3 project areas: the Quoddy Bay LNG project; the Downeast LNG project; and the Calais LNG project. The consequences of vapour clouds and pool fires were considered, as well as the overall hazards associated with a large LNG spill. Evaluation scenarios were considered for leaks and minor releases. Transportation and navigational issues included ship specifications, traffic movements and route analyses. Issues related to whales and hatcheries were considered. Emergency preparedness and response plans were included. An assessment of cumulative risks in the region was also provided. 182 refs., 65 tabs., 23 figs.

  16. Materials and structures under shock and impact

    CERN Document Server

    Bailly, Patrice

    2013-01-01

    In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

  17. Numerical Modeling of the Araguainha Impact Structure, Brazil

    Science.gov (United States)

    Vasconcelos, M. A. R.; Crósta, A. P.; Wünnemann, K.; Collins, G. S.; Reimold, W. U.; Köster, P.

    2016-08-01

    The Araguainha structure is the largest complex impact structure in South America. It was formed in sedimentary rocks overlaying a granitic basement.We used the iSALEcode to simulate the formation of the Araguainha impact structure.

  18. ZOOPLANKTON COMMUNITY STRUCTURE OF THE SEA SURFACE MICROLAYER NEAR NUCLEAR POWER PLANTS AND MARINE FISH CULTURE ZONES IN DAYA BAY

    Institute of Scientific and Technical Information of China (English)

    杨宇峰; 王肇鼎; 潘明祥; 焦念志

    2002-01-01

    The authors' surveys in May-June 1999 (two cruises) at six sampling stations near nuclear power plants (NPP) and marine fish culture zones in Daya Bay, Guangdong, revealed species composition, densities and body-size of thesea surface microlayer (SM) zooplankton (>35 μm). Results showed that protozoans and copepod nauplii were the predominant components, accounting for 65.40% to95.56% of total zooplankton in abundance. The size-frequency distributions showed that the frequency of micro-zooplankton (0.02-0.2 mm) reached 0.8235. The SM zooplankton community structure revealed in the present study was quite different from that revealed by investigations in the 1980s in Daya Bay. Difference of sampling method has important influence on the obtained zooplankton community structure. SM zooplankton consisted of micro- and mesozooplankton (0.2-2.0 mm), with micro-zooplankton being predominant. Some possible cause-effect relations between the zooplankton community structure and mariculture, nuclear power plants cooling systems and sampling method are discussed.``

  19. Macrozoobenthos community structure of the Bohai Bay in spring time%春季渤海湾大型底栖动物群落结构特征研究

    Institute of Scientific and Technical Information of China (English)

    蔡文倩; 孟伟; 刘录三; 朱延忠; 周娟

    2013-01-01

    . The results of MDS analysis was also approximately in accordance with the above results. In general, the macrozoobenthos community structure of Bohai Bay was impacted directly or indirectly by human pressures, such as coastal engineering projects, pollutants discharges, land reclamations and aquaculture. Compared with the historical data, the raacozoobenthos community structure of Bohai Bay had changed obviously, such as the decreased density and biomass, especially around the estuaries, outlets and harbors. Moreover, the offshore areas of this study area were also moderately or severely disturbed. According to the present data, the ecological status of Bohai Bay would be better than that of Laizhou Bay and Liaodong Bay.

  20. Seasonal Community Structure of Mesozooplankton in the Daya Bay, South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Huaxue; LI Kaizhi; HUANG Honghui; SONG Xingyu; YIN Jianqiang; HUANG Liangmin

    2013-01-01

    Mesozooplankton are key components of coastal ecosystems,linking the microbial food web to the classic food chain.In this study,species composition and abundance of mesozooplankton is studied for the Daya Bay in April (spring) and October (fall),2006.A total of 27 species of mesozooplankton were identified in spring and 58 species in fall.Dominant species were Oithona tenuis,Flaccisagitta enflata,Penilia avirostris and Centropages tenuiremis in spring,shifting to Microsetella norvegica,Oithona tenuis and Parvocalanus crassirostris in fall.Higher mesozooplankton abundance was found at Aotou Cove and Dapeng'ao Cove compared to other stations,indicating the influence of eutrophication on mesozooplankton community in the Daya Bay.The outbreak ofNoctiluca scintillans bloom in spring reduced the species diversity and abundance of mesozooplankton.

  1. Impact of brine acidification on hatchability, survival and reproduction of Artemia parthenogenetica and Artemia franciscana in salt ponds, Bohai Bay, China

    Science.gov (United States)

    Sui, Liying; Deng, Yuangao; Wang, Jing; Sorgeloos, Patrick; Van Stappen, Gilbert

    2014-01-01

    We studied the effect of pH (pH 5, 6, 7 and 8) on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay (BHB), Artemia franciscana from San Francisco Bay, and A. franciscana artificially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were significantly reduced when exposed to a culture medium at pH 5 for 18 d ( PArtemia to 48 h acid exposure varied with developmental stage, increasing in the following order: juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6-8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidification has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franciscana should be feasible at pH 7-8.

  2. Analysis of flexible structures under lateral impact

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, D. F. [Paul C. Kizzo and Associates Inc., Seismic Structural Group, Oakland, CA 94612 (United States); Razavi, H. [AREVA Inc., Civil Seismic Group, San Jose, CA 95119 (United States)

    2012-07-01

    Three methods for analysis of flexible structures under lateral impact are presented. The first proposed method (Method A) consists of: (1) modifying an available deceleration on a rigid target with conservation principles to account for structural flexibility; and (2) transient nonlinear analysis of the structure with the corrected forcing function. The second proposed method (Method B) is similar to Method A in obtaining the forcing function but it solves the equations of motion of an idealized two-degree-of-freedom system instead of directly using conservation principles. The last method simply provides the maximum force in the structure using the conservation of energy and linear momentum. A coupled simulation is also performed in LS-DYNA and compared against the proposed methods. A case study is presented to illustrate the applicability of all three methods and the LS-DYNA simulation. (authors)

  3. Intraguild predation between small pelagic fish in the Bay of Biscay: impact on anchovy (Engraulis encrasicolus L.) egg mortality

    KAUST Repository

    Bachiller, Eneko

    2015-05-12

    Small pelagic fish can play an important role in various ecosystems linking lower and upper trophic levels. Among the factor behind the observed inter-annual variations in small pelagic fish abundance, intra- and inter-specific trophic interactions could have a strong impact on the recruitment variability (e.g. anchovy). Egg cannibalism observed in anchovies has been postulated to be a mechanism that determines the upper limit of the population density and self-regulates the population abundance of the species. On the other hand, predation by other guild species is commonly considered as a regulation mechanism between competing species. This study provides empirical evidence of anchovy cannibalism and predation of the main small pelagic fish species on anchovy eggs and estimates the effect of intraguild predation on the anchovy egg mortality rate. Results show that, depending on the year (2008–2009), up to 33 % of the total anchovy egg mortality was the result of sardine predation and up to 4 % was the result of egg cannibalism together with predation by Atlantic and Atlantic Chub mackerel and sprat. Results also indicate that in the Bay of Biscay, fluctuations in the survival index of the early life stages of anchovy are likely to be attributable at least in part to egg cannibalism and especially to a high sardine predation on anchovy eggs. © 2015 Springer-Verlag Berlin Heidelberg

  4. Radiative properties of Bay of Bengal aerosols: Spatial distinctiveness and source impacts

    Science.gov (United States)

    Babu, S. Suresh; Gogoi, Mukunda M.; Kumar, V. H. Arun; Nair, Vijayakumar S.; Moorthy, K. Krishna

    2012-03-01

    Simultaneous and collocated measurements of spectrally resolved scattering and absorption coefficients and mass concentration of near-surface composite aerosols in the marine atmosphere over the Bay of Bengal (BOB), along with incoming shortwave (0.3-3 μm) global solar radiation and columnar spectral aerosol optical depths (AOD), were made on a research cruise during the winter phase of the Integrated Campaign for Aerosols, Gases and Radiation Budget (W-ICARB). The aerosol radiative properties revealed distinct spatial features associated with the contrasting outflows from Indo-Gangetic Plain (IGP) and East Asia. Both scattering and absorption coefficients depicted very high values (>200 and >15 Mm-1) over the northwestern and southeastern BOB and extremely low values (<50 and <10 Mm-1) over the central BOB. The mean value of the total scattering coefficient at 550 nm (˜123.7 ± 85.3 Mm-1) over the entire BOB during winter was higher than the mean values (˜94 ± 47 Mm-1) reported for the premonsoon season. While SSA at 550 nm showed very low values (<0.8) over a very large region in the central BOB and moderately low values over the southern BOB (˜0.85-0.9), the columnar AOD varied from the least values of ˜0.1 over the northeastern BOB to the highest values of ˜0.8 over the northwestern BOB. While significant cooling was observed at the top of the atmosphere and surface over the northwestern BOB, the atmospheric forcing was found to be significantly high (˜15 W m-2) over the southern BOB, where the aerosol radiative forcing efficiency (ARFE) at the surface was also found to be high. Examination of the Moderate Resolution Imaging Spectroradiometer (MODIS)-derived fire count along with the advection pathways revealed a strong contribution from the emissions of biomass smoke from East Asia, which might be contributing to the enhanced aerosol induced warming over the southern BOB. However, the ARFE at the surface was low over the northwestern BOB, where the

  5. Diets and trophic-guild structure of a diverse fish assemblage in Chesapeake Bay, U.S.A.

    Science.gov (United States)

    Buchheister, A; Latour, R J

    2015-03-01

    Dietary habits and trophic-guild structure were examined in a fish assemblage (47 species) of the Chesapeake Bay estuary, U.S.A., using 10 years of data from >25 000 fish stomachs. The assemblage was comprised of 10 statistically significant trophic guilds that were principally differentiated by the relative amounts of Mysida, Bivalvia, Polychaeta, Teleostei and other Crustacea in the diets. These guilds were broadly aggregated into five trophic categories: piscivores, zooplanktivores, benthivores, crustacivores and miscellaneous consumers. Food web structure was largely dictated by gradients in habitat (benthic to pelagic) and prey size. Size classes within piscivorous species were more likely to be classified into different guilds, reflecting stronger dietary changes through ontogeny relative to benthivores and other guilds. Relative to predator species and predator size, the month of sampling had negligible effects on dietary differences within the assemblage. A majority of sampled fishes derived most of their nutrition from non-pelagic prey sources, suggesting a strong coupling of fish production to benthic and demersal food resources. Mysida (predominantly the opossum shrimp Neomysis americana) contributed substantially to the diets of over 25% of the sampled predator groups, indicating that this species is a critical, but underappreciated, node in the Chesapeake Bay food web.

  6. Sex ratio and size structure of Micropogonias furnieri (Desmarest, 1823 (Perciformes, Sciaenidae in Sepetiba Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    R. N. Vicentini

    Full Text Available Sex ratio and size structure constitute basic information in assessing reproductive potential and estimating stock size in fish populations. One hundred fifty-one individuals of Micropogonias furnieri caught by experimental otter trawls, in three zones (inner, central, and outer of Sepetiba Bay between October 1998 and September 1999 were examined. Males outnumbered females (1.3:1.0 in all zones but no significant differences were detected. Only in the outer zone (5.0:1.0 were male/female rates significantly different according to the chi-square test. No temporal differences were observed in sex ratio. Fish size ranged from 81 to 244 mm total length (TL with significant differences in 155 to 185 mm TL size classes, where males predominated, and a slightly higher number of females were observed for the smaller size class (TL = 95-150 mm. Size distribution varied according to the zone, with juveniles predominating in the inner and adults in the outer zone. Spatial difference in size structure observed in this study indicates that the inner bay is a rearing ground during the first life-cycle period, and movement toward the sea occurs as fish increase in size.

  7. Natural Environmental Changes versus Human Impact in a Florida Estuary (Rookery Bay, USA)

    NARCIS (Netherlands)

    Lammers, J.M.; Soelen, E.E. van; Donders, T.H.; Wagner-Cremer, F.; Damsté, J.S.S.; Reichart, G.J.

    2013-01-01

    Assessing the impact of climate change and anthropogenic activity on Florida coastal areas requires a thorough understanding of natural climate variability. The available instrumental record, however, is too short and too limited to capture the full range of natural variability. In order to provide

  8. Subcellular partitioning profiles and metallothionein levels in indigenous clams Moerella iridescens from a metal-impacted coastal bay

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zaosheng, E-mail: zswang@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Feng, Chenglian; Ye, Chun [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Youshao [State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301 (China); Yan, Changzhou, E-mail: czyan@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China); Li, Rui; Yan, Yijun; Chi, Qiaoqiao [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China)

    2016-07-15

    Highlights: • Subcellular partitioning profile of metals were investigated in biomonitor organism. • Cu, Zn and Cd levels in main fraction of HSP increase along accumulation gradients. • Despite MTs as the major binding pool, detoxification of Cd and Pb was incomplete. • Induced MTs were sequentially correlated with Cu, Zn and Cd levels in HSP fraction. • Intracellular metal fates highlighted the metabolic availability within organism. - Abstract: In this study, the effect of environmental metal exposure on the accumulation and subcellular distribution of metals in the digestive gland of clams with special emphasis on metallothioneins (MTs) was investigated. Specimens of indigenous Moerella iridescens were collected from different natural habitats in Maluan Bay (China), characterized by varying levels of metal contamination. The digestive glands were excised, homogenized and six subcellular fractions were separated by differential centrifugation procedures and analyzed for their Cu, Zn, Cd and Pb contents. MTs were quantified independently by spectrophotometric measurements of thiols. Site-specific differences were observed in total metal concentrations in the tissues, correlating well with variable environmental metal concentrations and reflecting the gradient trends in metal contamination. Concentrations of the non-essential Cd and Pb were more responsive to environmental exposure gradients than were tissue concentrations of the essential metals, Cu and Zn. Subcellular partitioning profiles for Cu, Zn and Cd were relatively similar, with the heat-stable protein (HSP) fraction as the dominant metal-binding compartment, whereas for Pb this fraction was much less important. The variations in proportions and concentrations of metals in this fraction along with the metal bioaccumulation gradients suggested that the induced MTs play an important role in metal homeostasis and detoxification for M. iridescens in the metal-contaminated bay. Nevertheless

  9. Genetic Diversity Analysis of the Natural Populations of Mediterra­nean Mussels [Mytilus galloprovincialis (Lmk.] in Agadir Bay: Assess­ment of the Molecular Polymorphism and Environmental Impact

    Directory of Open Access Journals (Sweden)

    Amal Korrida

    2010-07-01

    Full Text Available Mediterranean mussel (Mytilus galloprovincialis Lmk has a great environmental and economic importance for Morocco. This work studies the genetic structure and impact of chemical pollution on three different marine populations of Mytilus galloprovincialis that live within Agadir bay. Three collections were made at two clean sites (Cape Ghir and Cape Aglou and at an impacted site exposed to intense boating and industrial activities (Anza. A 300-bp portion of the mitochondrial DNA coding-region Cytochrome C Oxidase subunit 1 (COI was studied by polymerase chain reaction (PCR and DNA sequencing reactions to assess and evaluate amounts of polymorphism in each site. Genetic analysis using COI for 64 individuals showed no significant differentiation between the three subpopulations. AMOVA demonstrated that only 2.83% of variation exists between populations. Besides the genetic evidence presented herein, mussel’s adaptation mechanisms and strategies to marine pollution are also discussed.

  10. Impact of silk biomaterial structure on proteolysis.

    Science.gov (United States)

    Brown, Joseph; Lu, Chia-Li; Coburn, Jeannine; Kaplan, David L

    2015-01-01

    The goal of this study was to determine the impact of silk biomaterial structure (e.g. solution, hydrogel, film) on proteolytic susceptibility. In vitro enzymatic degradation of silk fibroin hydrogels and films was studied using a variety of proteases, including proteinase K, protease XIV, α-chymotrypsin, collagenase, matrix metalloproteinase-1 (MMP-1) and MMP-2. Hydrogels were used to assess bulk degradation while films were used to assess surface degradation. Weight loss, secondary structure determined by Fourier transform infrared spectroscopy and degradation products analyzed via sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to evaluate degradation over 5 days. Silk films were significantly degraded by proteinase K, while silk hydrogels were degraded more extensively by protease XIV and proteinase K. Collagenase preferentially degraded the β-sheet content in hydrogels while protease XIV and α-chymotrypsin degraded the amorphous structures. MMP-1 and MMP-2 degraded silk fibroin in solution, resulting in a decrease in peptide fragment sizes over time. The link between primary sequence mapping with protease susceptibility provides insight into the role of secondary structure in impacting proteolytic access by comparing solution vs. solid state proteolytic susceptibility.

  11. The unnatural history of Kāne‘ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts

    OpenAIRE

    Keisha D. Bahr; Paul L Jokiel; Toonen, Robert J.

    2015-01-01

    Kāneʻohe Bay, which is located on the on the NE coast of Oʻahu, Hawaiʻi, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāneʻohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Loʻe (Coconut Island) in the southern region of the bay became home to the Hawaiʻi Inst...

  12. Structure and dynamics of the macrobenthic communities of Ubatuba Bay, southeastern Brazilian Coast

    Directory of Open Access Journals (Sweden)

    Maria Fernanda Lopes dos Santos

    2004-03-01

    Full Text Available Species composition, distribution, density, biomass, diversity and trophic relationships of the macrobenthic communities in Ubatuba Bay, southeastern Brazilian coast, were investigated seasonally from August 1995 to June 1996. Sampling was carried out at 9 stations of between 4 and 13 m depth and taken in duplicate with a 0.1m² van Veen grab. Two hundred and five macrofaunal species were identified, presenting low dominance and frequency. Polychaetes and nematodes dominated, representing 89% of the whole fauna. Spatial variations in the structure of the communities were correlated to sediment type whereas seasonal variations were correlated to the increase in wave size and current disturbance over the substrate during the rainy period. Carnivore and surface deposit-feeder polychaetes were dominant, totalling 81% of the species. Mean grain size, fine sand, very fine sand, silt and clay contents were among the main factors related to the patterns of macrofaunal distribution, density and diversity and to the dominance of trophic groups. Multivariate analysis showed that the area may be divided into two groups of stations each of them characterized, respectively, by the presence of Magelona papillicornis and Mediomastus capensis.A composição, distribuição, densidade, biomassa, diversidade e relações tróficas das comunidades macrobênticas da Enseada de Ubatuba, costa sudeste brasileira, foram estudadas sazonalmente, de agosto de 1995 a junho de 1996. As amostragens foram realizadas em 9 estações de coleta, situadas entre 4 e 13 m de profundidade, e obtidas em duplicata com pegador de fundo van Veen de 0,1 m² de área amostral. Duzentas e cinco espécies macrobênticas foram obtidas, a maioria apresentando baixa dominância e freqüência. Poliquetas e nemátodes dominaram, representando 89% da fauna total. As variações espaciais na estrutura das comunidades foram correlacionadas ao tipo de sedimento, ao passo que as varia

  13. Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay

    Science.gov (United States)

    Estes, Maurice G.; Al-Hamdan, Mohammed; Thom, Ron; Quattrochi, Dale; Woodruff, Dana; Judd, Chaeli; Ellism Jean; Watson, Brian; Rodriguez, Hugo; Johnson, Hoyt

    2009-01-01

    There is a continued need to understand how human activities along the northern Gulf of Mexico coast are impacting the natural ecosystems. The gulf coast is experiencing rapid population growth and associated land cover/land use change. Mobile Bay, AL is a designated pilot region of the Gulf of Mexico Alliance (GOMA) and is the focus area of many current NASA and NOAA studies, for example. This is a critical region, both ecologically and economically to the entire United States because it has the fourth largest freshwater inflow in the continental USA, is a vital nursery habitat for commercially and recreational important fisheries, and houses a working waterfront and port that is expanding. Watershed and hydrodynamic modeling has been performed for Mobile Bay to evaluate the impact of land use change in Mobile and Baldwin counties on the aquatic ecosystem. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use Scenarios in 1948, 1992, 2001, and 2030. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on observed trends. All land use scenarios were developed to a common land classification system developed by merging the 1992 and 2001 National Land Cover Data (NLCD). The LSPC model output provides changes in flow, temperature, sediments and general water quality for 22 discharge points into the Bay. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment concentrations on a grid with four vertical profiles throughout the Bay s aquatic ecosystems. The models were calibrated using in-situ data collected at sampling stations in and around Mobile bay. This phase of the project has focused on sediment modeling because of its significant influence on light attenuation which is a critical factor in the health of submerged aquatic

  14. Observations of pockmark flow structure in Belfast Bay, Maine, Part 3: implications for sediment transport

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-01-01

    Current observations and sediment characteristics acquired within and along the rim of two pockmarks in Belfast Bay, Maine, were used to characterize periods of sediment transport and to investigate conditions favorable to the settling of suspended sediment. Hourly averaged Shields parameters determined from horizontal current velocity profiles within the center of each pockmark never exceed the critical value (approximated with the theoretical model of Dade et al. 1992). However, Shields parameters estimated at the pockmark rims periodically exceed the critical value, consistent with conditions that support the onset of sediment transport and suspension. Below the rim in the near-center of each pockmark, depth-averaged vertical velocities were less than zero (downward) 60% and 55% of the time in the northern and southern pockmarks, and were often comparable to depth-averaged horizontal velocities. Along the rim, depth-averaged vertical velocities over the lower 8 m of the water column were primarily downward but much less than depth-averaged horizontal velocities indicating that suspended sediment may be moved to distant locations. Maximum grain sizes capable of remaining in suspension under terminal settling flow conditions (ranging 10–170 μm) were typically much greater than the observed median grain diameter (about 7 μm) at the bed. During upwelling flow within the pockmarks, and in the absence of flocculation, suspended sediment would not settle. The greater frequency of predicted periods of sediment transport along the rim of the southern pockmark is consistent with pockmark morphology in Belfast Bay, which transitions from more spherical to more elongated toward the south, suggesting near-bed sediment transport may contribute to post-formation pockmark evolution during typical conditions in Belfast Bay.

  15. Observations of pockmark flow structure in Belfast Bay, Maine, Part 3: implications for sediment transport

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-02-01

    Current observations and sediment characteristics acquired within and along the rim of two pockmarks in Belfast Bay, Maine, were used to characterize periods of sediment transport and to investigate conditions favorable to the settling of suspended sediment. Hourly averaged Shields parameters determined from horizontal current velocity profiles within the center of each pockmark never exceed the critical value (approximated with the theoretical model of Dade et al. 1992). However, Shields parameters estimated at the pockmark rims periodically exceed the critical value, consistent with conditions that support the onset of sediment transport and suspension. Below the rim in the near-center of each pockmark, depth-averaged vertical velocities were less than zero (downward) 60% and 55% of the time in the northern and southern pockmarks, and were often comparable to depth-averaged horizontal velocities. Along the rim, depth-averaged vertical velocities over the lower 8 m of the water column were primarily downward but much less than depth-averaged horizontal velocities indicating that suspended sediment may be moved to distant locations. Maximum grain sizes capable of remaining in suspension under terminal settling flow conditions (ranging 10-170 μm) were typically much greater than the observed median grain diameter (about 7 μm) at the bed. During upwelling flow within the pockmarks, and in the absence of flocculation, suspended sediment would not settle. The greater frequency of predicted periods of sediment transport along the rim of the southern pockmark is consistent with pockmark morphology in Belfast Bay, which transitions from more spherical to more elongated toward the south, suggesting near-bed sediment transport may contribute to post-formation pockmark evolution during typical conditions in Belfast Bay.

  16. Copper and Other Contaminants in King's Bay and Crystal River (Florida) Sediments: Implications for Impact on the West Indian Manatee

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Contaminant concentrations were measured in 25 sediment samples collected from King's Bay, the headwaters of the Crystal River, Florida. Total organic carbon content...

  17. Impact of freshwater influx on the cyclogenesis, tracks of cyclones and air-sea coupling over the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Sarma, M.S.S.; Jenson, G.V.; Vidya, P.J.

    depressions over the northern Bay (>17°N) during June-September, severe cyclonic storms of hurricane intensity over the Andaman Sea and southeastern Bay during October-November (post-southwest monsoon). In some years, the remnants of the western Pacific... typhoons rejuvenate (11) over the Andaman Sea and intensify into depressions. The variability in the frequency and path of the post monsoon weather disturbances is also correlated with the EI Nino Southern Oscillation (ENSO) events (12). Earlier studies...

  18. Impact of off-road vehicles (ORVs) on ghost crabs of sandy beaches with traffic restrictions: a case study of Sodwana Bay, South Africa.

    Science.gov (United States)

    Lucrezi, Serena; Saayman, Melville; van der Merwe, Peet

    2014-03-01

    Off-road vehicles (ORVs) are popular in coastal recreation, although they have negative impacts on sandy shores. In South Africa, ORVs are banned from most coastal areas, while some areas are designated for restricted ORV use, providing an opportunity to assess whether ORV traffic restrictions translate into biological returns. In Sodwana Bay, the impact of ORVs on ghost crab populations was investigated. During Easter 2012, ghost crab burrows were counted on beach sections open and closed to traffic. Burrow density in the Impact section was less than a third that of the Reference section, and by the end of the study burrow size in the Impact section was half that of the Reference section. ORV traffic caused a shift in burrow distribution to the Lower beach. However, differences in burrow densities between sections were 14 times smaller than differences obtained at a time when ORV use in Sodwana Bay was not controlled. While confirming the well-established detrimental effects of ORV use on sandy beach ecosystems, results demonstrated that traffic restrictions on beaches measurably minimize impacts to the fauna, thus translating into clear-cut biological returns.

  19. Impacts of representing sea-level rise uncertainty on future flood risks: An example from San Francisco Bay

    Science.gov (United States)

    Oddo, Perry C.; Keller, Klaus

    2017-01-01

    Rising sea levels increase the probability of future coastal flooding. Many decision-makers use risk analyses to inform the design of sea-level rise (SLR) adaptation strategies. These analyses are often silent on potentially relevant uncertainties. For example, some previous risk analyses use the expected, best, or large quantile (i.e., 90%) estimate of future SLR. Here, we use a case study to quantify and illustrate how neglecting SLR uncertainties can bias risk projections. Specifically, we focus on the future 100-yr (1% annual exceedance probability) coastal flood height (storm surge including SLR) in the year 2100 in the San Francisco Bay area. We find that accounting for uncertainty in future SLR increases the return level (the height associated with a probability of occurrence) by half a meter from roughly 2.2 to 2.7 m, compared to using the mean sea-level projection. Accounting for this uncertainty also changes the shape of the relationship between the return period (the inverse probability that an event of interest will occur) and the return level. For instance, incorporating uncertainties shortens the return period associated with the 2.2 m return level from a 100-yr to roughly a 7-yr return period (∼15% probability). Additionally, accounting for this uncertainty doubles the area at risk of flooding (the area to be flooded under a certain height; e.g., the 100-yr flood height) in San Francisco. These results indicate that the method of accounting for future SLR can have considerable impacts on the design of flood risk management strategies. PMID:28350884

  20. Introduction of structural health and safety monitoring warning systems for Shenzhen-Hong Kong Western Corridor Shenzhen Bay Bridge

    Science.gov (United States)

    Li, N.; Zhang, X. Y.; Zhou, X. T.; Leng, J.; Liang, Z.; Zheng, C.; Sun, X. F.

    2008-03-01

    Though the brief introduction of the completed structural health and safety monitoring warning systems for Shenzhen-Hongkong western corridor Shenzhen bay highway bridge (SZBHMS), the self-developed system frame, hardware and software scheme of this practical research project are systematically discussed in this paper. The data acquisition and transmission hardware and the basic software based on the NI (National Instruments) Company virtual instruments technology were selected in this system, which adopted GPS time service receiver technology and so on. The objectives are to establish the structural safety monitoring and status evaluation system to monitor the structural responses and working conditions in real time and to analyze the structural working statue using information obtained from the measured data. It will be also provided the scientific decision-making bases for the bridge management and maintenance. Potential technical approaches to the structural safety warning systems, status identification and evaluation method are presented. The result indicated that the performance of the system has achieved the desired objectives, ensure the longterm high reliability, real time concurrence and advanced technology of SZBHMS. The innovate achievement which is the first time to implement in domestic, provide the reference for long-span bridge structural health and safety monitoring warning systems design.

  1. Food insecurity, chronic illness, and gentrification in the San Francisco Bay Area: An example of structural violence in United States public policy.

    Science.gov (United States)

    Whittle, Henry J; Palar, Kartika; Hufstedler, Lee Lemus; Seligman, Hilary K; Frongillo, Edward A; Weiser, Sheri D

    2015-10-01

    Food insecurity continues to be a major challenge in the United States, affecting 49 million individuals. Quantitative studies show that food insecurity has serious negative health impacts among individuals suffering from chronic illnesses, including people living with HIV/AIDS (PLHIV). Formulating effective interventions and policies to combat these health effects requires an in-depth understanding of the lived experience and structural drivers of food insecurity. Few studies, however, have elucidated these phenomena among people living with chronic illnesses in resource-rich settings, including in the United States. Here we sought to explore the experiences and structural determinants of food insecurity among a group of low-income PLHIV in the San Francisco Bay Area. Thirty-four semi-structured in-depth interviews were conducted with low-income PLHIV receiving food assistance from a local non-profit in San Francisco and Alameda County, California, between April and June 2014. Interview transcripts were coded and analysed according to content analysis methods following an inductive-deductive approach. The lived experience of food insecurity among participants included periods of insufficient quantity of food and resultant hunger, as well as long-term struggles with quality of food that led to concerns about the poor health effects of a cheap diet. Participants also reported procuring food using personally and socially unacceptable strategies, including long-term dependence on friends, family, and charity; stealing food; exchanging sex for food; and selling controlled substances. Food insecurity often arose from the need to pay high rents exacerbated by gentrification while receiving limited disability income--​a situation resulting in large part from the convergence of long-standing urban policies amenable to gentrification and an outdated disability policy that constrains financial viability. The experiences of food insecurity described by participants in this

  2. Dynamics of bacterial community structure on intertidal sandflat inhabited by the ghost shrimp Nihonotrypaea harmandi (Decapoda: Axiidea: Callianassidae) in Tomioka Bay, Amakusa, Japan.

    Science.gov (United States)

    Wada, Minoru; Urakawa, Tatsuyuki; Tamaki, Akio

    2016-02-01

    Callianassid (ghost) shrimp has been claimed as an ecosystem engineer, as it is one of the most powerful bioturbating macrobenthos in intertidal sandflats. However, our knowledge about the relationship between areal distribution of bottom-dwelling ghost shrimps and dynamics of sediment microbial community structure remains obscured. We used automated ribosomal intergenic spacer analysis (ARISA) to reveal the bacterial community dynamics in the sediment of intertidal sandflat of Tomioka Bay, Kyushu, Japan, which is predominantly inhabited by a burrow-dwelling callianassid shrimp Nihonotrypaea harmandi. We found that the bacterial community structures of high and middle shrimp population areas were significantly differentiated from those of low population area (ANOSIM, R=0.10-0.18, p0.1). These results illustrated the potential importance of shrimp population density as a key factor in shaping the bacterial community structure and interpreting their dynamics in the sandflat. Furthermore, greater similarity between burrow and non-burrow communities was found in samples taken in autumn through winter than in those in summer (one-way ANOVA, pshrimp in permeable sandflat would strongly homogenize sediment particles, enhance solute transport surrounding the burrow and ambient subsurface substrate, and therefore reduce spatial differentiation of the bacterial community structure between the two sites. A comparison between present and previous studies of axiidean (former taxonomic group name, thalassinidean) ghost shrimps provides us with a comprehensive understanding of the shrimps' impacts on bacterial community dynamics, highlighting the importance of sediment permeability, a characteristic determined by the type of sediment, as a key controlling factor to shape spatial heterogeneity of bacterial community structure around burrow.

  3. Hurricane Sandy science plan: impacts of storm surge, including disturbed estuarine and bay hydrology

    Science.gov (United States)

    Caskie, Sarah A.

    2013-01-01

    Hurricane Sandy devastated some of the most heavily populated eastern coastal areas of the Nation. With a storm surge peaking at more than 19 feet, the powerful landscape-altering destruction of Hurricane Sandy is a stark reminder of why the Nation must become more resilient to coastal hazards. In response to this natural disaster, the U.S. Geological Survey (USGS) received a total of $41.2 million in supplemental appropriations from the Department of the Interior (DOI) to support response, recovery, and rebuilding efforts. These funds support a science plan that will provide critical scientific information necessary to inform management decisions for recovery of coastal communities, and aid in preparation for future natural hazards. This science plan is designed to coordinate continuing USGS activities with stakeholders and other agencies to improve data collection and analysis that will guide recovery and restoration efforts. The science plan is split into five distinct themes: • Coastal topography and bathymetry • Impacts to coastal beaches and barriers

  4. The Guarda structure (Portugal): Impact structure or not? Microstructural studies of Quartz, Zircon and Monazite

    NARCIS (Netherlands)

    Zalinge, M.E. van; Hamers, M.F.; Drury, M.R.

    2012-01-01

    The Guarda Structure in north-eastern Portugal has been proposed as a potential impact structure. We have studied the structure in detail, but no field or microscopic evidence has been found to support the impact hypothesis

  5. Sediment and Crustal Structure along 85oE and Ninetyeast Ridges in the Bay of Bengal: Geodynamic Implications

    Science.gov (United States)

    Munukutla, R.; Gangumalla, S. R.; Sreejith, K. M.; Krishna, K. S.; Bull, J. M.

    2015-12-01

    The Bay of Bengal (BOB) region is characterized by the presence of two linear N-S trending aseismic ridges, the 85°E and Ninetyeast ridges which have progressively buried below thick sediments towards north. We present here the results of an integrated interpretation of geophysical data using multichannel seismic reflection, gravity and magnetic datasets over these two ridges to study the crustal structure and mode of their emplacement. The ridges divide the deep sedimentary BOB region into three major sub-basins. Considering the sediment deposition pattern within the sub-basins and over the ridges, it is found that both ridge structures have played a role in sediment dispersal pattern during the pre- and post Bengal Fan sedimentation. The Geoid-Topography Ratio (GTR) analysis indicates that both the ridges are compensated at shallow depths. Seismically constrained gravity and magnetic models and flexural gravity modeling over these ridges support their volcanic origin, and suggest the following: i) 85°E Ridge was emplaced in off-ridge environment (Te=10-15 km); ii) the higher Te values of ~ 25 km over the Afanasy Nikitin Seamount (ANS) reflect the secondary emplacement of the seamount peaks in off-ridge environment, iii) that the emplacement of the Ninetyeast Ridge north of 2°N occurred in an off-ridge environment as indicated by higher Te values (25-30 km). These results attain significance in terms of understanding of the interactions between plume- volcanism and lithosphere in the Bay of Bengal.

  6. Combined geophysical and geochemical tracer techniques to assess rates and impact of submarine groundwater discharge into Tampa Bay, Florida

    Science.gov (United States)

    Swarzenski, P. W.; Baskaran, M.; Reich, C.; Greenwood, J.

    2006-12-01

    It is now widely accepted that water and constituent transport by submarine groundwater discharge (SGD) can be ecologically important within some coastal environments. However, the nature of this discharge, which can exhibit tremendously temporal and spatial heterogeneity, renders SGD most often difficult to identify and quantify. U/Th series geochemical tracers and new geophysical tools have been developed that now can yield system-wide information on SGD rates and processes. The objective of this study was to apply naturally- occurring Ra and Rn isotopes to derive SGD rates bay wide, and then examine to the geologic controls on SGD in this system with streaming and time series resistivity measurements. Submarine groundwater discharge rates calculated using a mass balance of excess Ra-226 ranged from 2 to 14 L per square-m per d. When extrapolated to the total shoreline length of the bay, such SGD rates ranged from 2 to 10 cubic-m per d per m of shoreline. High-resolution time series and streaming resistivity measurements confirm that SGD within Tampa Bay can be separated into a near-shore and mid-bay component that involve different water masses and unique mixing processes. SGD-derived nutrient loading estimates in Tampa bay will be compared to similar riverine estimates.

  7. [Effects of sediment dredging on benthos community structure and water quality in Zhushan Bay].

    Science.gov (United States)

    Liu, Guo-Feng; Zhang, Zhi-Yong; Liu, Hai-Qin; Zhong, Ji-Cheng; Yan, Shao-Hua; Fan, Cheng-Xin

    2010-11-01

    We surveyed the changes of macro-benthos community composition and nutrients concentration in water in Zhushan Bay after it had been dredged 6 months, which aimed to remove the polluted surface sediments. The results showed that the main benthos in the dredged and un-dredged sediments were Limodrilus hoffmeisteri, Pelopia and Bellamya aeruginosa; compared to the un-dredged sediments, the bio-diversity of dredged areas became lower. However, its biomass became higher than that in un-dredged areas. Concentration range changes of TN and TP in overlying water was 1.64-4.45 mg/L and 0.133-0.258 mg/L, respectively. The post-dredged sediments were still in a higher state of nutrients for the higher concentration nutrients in overlying water, macro-benthos were the species that lived in a serious polluted water environment. Using Shannon-Weaver, Simpson, and Goodnight benthic index to evaluate the results show that the dredged area is in the moderately polluted level, but un-dredged area is in the middle-heavily polluted level. According to the benthos fauna surveys and water quality monitoring results, the effective of sediment dredging could play its role only the strict control on the external pollution resources have been made and reduces the effects of polluted water on the sediments.

  8. Impact of land-use change and hard structures on the evolution of fringing marsh shorelines

    Science.gov (United States)

    Mattheus, Christopher R.; Rodriguez, Antonio B.; McKee, Brent A.; Currin, Carolyn A.

    2010-07-01

    Estuarine fringe marshes provide essential ecosystem services to coastal regions, including carbon sequestration and provision of shelter and nursery grounds for aquatic and terrestrial animals. The ability of a marsh to sustain itself by vertical accretion in response to sea-level rise is, in part, limited by inorganic sediment supply. Models attempting to forecast salt-marsh response to future sea-level rise commonly ignore land-use changes, despite the recent coastal population boom and the potential of land-use changes to alter sediment sources and modify established sediment-transport pathways. This study investigates the impacts of landscape modifications, which are typical of coastal areas, on the nearshore sedimentation and edge evolution of two fringing marshes. The sites examined include a marsh fringing the upper bay and a marsh fringing a beach ridge on the estuarine shoreline of a barrier island. Both sites are located in the same estuarine system, have similar hydrologic settings and comparable vegetation densities. Previous work, marsh cores, and a historical record from aerial photos indicate that although the fringe marshes are in different geomorphic locations, prior to anthropogenic modifications they were similar in terms of nearshore-sediment composition, scarp-shoreline morphology, and shoreline trajectory. The upper-bay marsh was impacted by the introduction of tree farming in the watershed of a tributary creek to the upper bay, which increased upland erosion and caused higher sedimentation rates in the estuary. The back-barrier marsh, which received no contribution from the tree farm because it is distal with respect to river input, was modified by the installation of a pier and rock sill. Terrestrial LIDAR, surface elevation tables, and accretion rates obtained from radioisotope analyses show that the deforestation induced high rates of nearshore and marsh accretion at the upper-bay site, which is promoting marsh colonization and expansion

  9. Reducing Nutrients and Nutrient Impacts Priority Issue Team - St. Louis Bay Project: Implementing Nutrients PIT Action Step 1.1

    Science.gov (United States)

    Mason, Ted

    2011-01-01

    The NASA Applied Science & Technology Project Office at Stennis Space Center(SSC) used satellites, in-situ measurements and computational modeling to study relationships between water quality in St. Louis Bay, Mississippi and the watershed characteristics of the Jourdan and Wolf rivers from 2000-2010.

  10. Study on headland-bay sandy coast stability in South China coasts

    Science.gov (United States)

    Yu, Ji-Tao; Chen, Zi-Shen

    2011-03-01

    Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection. However, little concern focuses on this in China. The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches. This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China. The empirical bay equation can morphologically estimate beach stabilization state, but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades. By using Digital Shoreline Analysis System suggested by USGS, the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000. The conclusions of this paper include that (a) most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000; (b) two bays, Haimen Bay and Hailingshan Bay, originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation, have been unstable by the influence of coastal engineering; and (c) these 31 bays have different recession and accretion characters occurring in some bays and some segments. On the one hand, some bays totally exhibit accretion, but some bays show erosion on the whole. Shanwei Bay, Houmen Bay, Pinghai Bay and Yazhou Bay have the similar planforms, characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments. On the other hand, different segments of some

  11. Lithosphere structure and upper mantle characteristics below the Bay of Bengal

    Science.gov (United States)

    Rao, G. Srinivasa; Radhakrishna, M.; Sreejith, K. M.; Krishna, K. S.; Bull, J. M.

    2016-07-01

    The oceanic lithosphere in the Bay of Bengal (BOB) formed 80-120 Ma following the breakup of eastern Gondwanaland. Since its formation, it has been affected by the emplacement of two long N-S trending linear aseismic ridges (85°E and Ninetyeast) and by the loading of ca. 20-km of sediments of the Bengal Fan. Here, we present the results of a combined spatial and spectral domain analysis of residual geoid, bathymetry and gravity data constrained by seismic reflection and refraction data. Self-consistent geoid and gravity modelling defined by temperature-dependent mantle densities along a N-S transect in the BOB region revealed that the depth to the lithosphere-asthenosphere boundary (LAB) deepens steeply from 77 km in the south to 127 km in north, with the greater thickness being anomalously thick compared to the lithosphere of similar-age beneath the Pacific Ocean. The Geoid-Topography Ratio (GTR) analysis of the 85°E and Ninetyeast ridges indicate that they are compensated at shallow depths. Effective elastic thickness (Te) estimates obtained through admittance/ coherence analysis as well as the flexural modelling along these ridges led to the conclusions: (i) 85°E Ridge was emplaced in off-ridge environment (Te = 10-15 km); (ii) the higher Te values of ˜25 km over the Afanasy Nikitin Seamount (ANS) reflect the secondary emplacement of the seamount peaks in off-ridge environment, (iii) that the emplacement of the Ninetyeast Ridge north of 2°N occurred in an off-ridge environment as indicated by higher Te values (25-30 km). Furthermore, the admittance analysis of geoid and bathymetry revealed that the admittance signatures at wavelengths >800 km are compensated by processes related to upper mantle convection.

  12. Freshwater seepages and ephemeral macroalgae proliferation in an intertidal bay: I Effect on benthic community structure and food web

    Science.gov (United States)

    Ouisse, Vincent; Riera, Pascal; Migné, Aline; Leroux, Cédric; Davoult, Dominique

    2011-01-01

    Freshwater seepages and ephemeral Enteromorpha spp. proliferation create heterogeneity at small spatial scale in intertidal sediment. Macrobenthic community diversity was compared between these two disturbances and their respective control points throughout the year 2007 at the Roscoff Aber Bay (Western English Channel, France). In March and September 2007, trophic community pathways of characteristic species were additionally studied using stable isotope ratios of carbon and nitrogen. The low salinity recorded at the freshwater seepage induced the exclusion of the main bioturbator and the presence of omnivores which modified the community composition by biotic pressure. Moreover, food web analyses clearly highlighted a separation at small spatial scale between the two trophic pathways of the impacted area and its control. On the contrary, little differences were observed owning to the ephemeral Enteromorpha spp. proliferation. This suggested a progressive and diffusive disturbance which was applied from the algal mat to the nearby area. However, seasonal changes were observed. First, the algal expansion phase increased the macrofauna diversity and foraminifers' abundance (meiofauna) and then acted as a physical barrier decreasing sediment and water column exchanges and decreasing the fauna diversity. This study highlights the need to take into account small spatial heterogeneity to avoid misinterpretations in intertidal ecology studies.

  13. CRED Fagatele Bay National Marine Sanctuary Bathymetric Position Index Habitat Structures 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathymetric Position Index (BPI) Structures are derived from derivatives of Simrad EM-3000 multibeam bathymetry (1 m and 3 m resolution). BPI structures are...

  14. Spatial Heterogeneity of Population Structure of the Mangrove Bruguiera gymnorrhiza at Yingluo Bay, South-China Coast

    Institute of Scientific and Technical Information of China (English)

    LIANGShi-Chu; DONGMing

    2004-01-01

    The spatial heterogeneity, including distribution pattern, tree perimeter and height differentiation, and canopy structure heterogeneity, of Bruguiera gymnorrhiza (L.) Lamk populations at Yingtuo Bay, South-China Coast was investigated using the positioning index (CE), differentiation index (TC and TH), Shannon-Wiener diversity index (D), and Ripley's K-functions. Most populations showed random distribution and low differentiation in perimeters and heights of individuals, while a few showed clumped distribution and clear differentiation. Canopy and gap patches were analyzed at multiple horizontal and vertical scales using geographic information system (GIS). The mosaic patterns of canopy and gap patches are different among populations, and could be quantitatively described with the Shannon-Wiener diversity index based on crown projection. The spatial heterogeneity of the canopy structure changed with spatial scales, but this kind of change would remain relatively stable over a range of scales. This scale range could be regarded as the referenced scale for a regeneration or ecological management unit for the forest.

  15. Implications of the Daya Bay observation of θ13 on the leptonic flavor mixing structure and CP violation

    Institute of Scientific and Technical Information of China (English)

    XING Zhi-Zhong

    2012-01-01

    The Daya Bay collaboration has recently reported its first (-V)e → (-V)e oscillation result which points to θ13 (~-) 8.8° ±0.8° (best-fit ±1σ range) or θ13 ≠ 0° at the 5.2σ level.The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and CP violation.Two phenomenological strategies are outlined:(1) the lepton flavor mixing matrix U consists of a constant leading term U0 and a small perturbation term AU; and (2) the mixing angles of U are associated with the lepton mass ratios.Some typical patterns of U0 are reexamined by constraining their respective perturbations with current experimental data.We illustrate a few possible ways to minimally correct U0 in order to fit the observed values of three mixing angles.We point out that the structure of U may exhibit an approximate μ-τ permutation symmetry in modulus,and reiterate the geometrical description of CP violation in terms of the leptonic unitarity triangles.The salient features of nine distinct parametrizations of U are summarized,and its Wolfenstein-like expansion is presented by taking U0 to be the democratic mixing pattern.

  16. Spatial variability in structural and functional aspects of macrofauna communities and their environmental parameters in the Jade Bay (Wadden Sea Lower Saxony, southern North Sea)

    Science.gov (United States)

    Schückel, Ulrike; Beck, Melanie; Kröncke, Ingrid

    2013-03-01

    Spatial distribution and functional structure of intertidal benthic macrofauna in relation to environmental variables in the Jade Bay (southern North Sea) were studied and compared with other intertidal areas of the Wadden Sea. A total of 128 stations covering the whole Jade Bay were sampled in summer 2009. A total of 114 taxa were found. Highest species numbers occurred in the subtidal areas, whereas highest mean abundances were found in the upper intertidal areas. Based on species abundance data, six significantly distinct macrofauna communities in the Jade Bay were identified and evaluated with multivariate statistics, univariate correlations and canonical correspondence analysis. Differences in these community patterns were caused by the response of the dominant species ( Hydrobia ulvae, Tubificoides benedii, Pygospio elegans, Caulleriella killariensis, Scoloplos armiger, Urothoe poseidonis, Microprotopus maculatus) to prevailing environmental conditions along the gradient from the lower and exposed sandy intertidal areas via intermediate mixed sediments to the upper mudflat areas. Distribution patterns in relation to tidal zonation were best explained by variability in submergence time, Chlorophyll a (chl a) content and sediment composition (mud content), which are proxies for hydrodynamic conditions and food availability. Species inventory and species richness were comparable with other intertidal areas of the Wadden Sea, but the Jade Bay differs from these areas regarding dominant species. Differences in sediment composition and morphological characteristics (macrotidal versus mesotidal Wadden Sea areas) are discussed for comparison of regional differences.

  17. Assessment of Containment Structures Against Missile Impact Threats

    Institute of Scientific and Technical Information of China (English)

    LI Q M

    2006-01-01

    In order to ensure the highest safety requirements,nuclear power plant structures (the containment structures,the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats.The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes,the failure of high speed rotating machineries and accidental drops.The external impact threats may come from airborne missiles,aircraft impact,explosion blast and fragments.The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed.Methods and procedures for the impact assessment of nuclear power plants are introduced.Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures.

  18. Knottin cyclization: impact on structure and dynamics

    Directory of Open Access Journals (Sweden)

    Gracy Jérôme

    2008-12-01

    Full Text Available Abstract Background Present in various species, the knottins (also referred to as inhibitor cystine knots constitute a group of extremely stable miniproteins with a plethora of biological activities. Owing to their small size and their high stability, knottins are considered as excellent leads or scaffolds in drug design. Two knottin families contain macrocyclic compounds, namely the cyclotides and the squash inhibitors. The cyclotide family nearly exclusively contains head-to-tail cyclized members. On the other hand, the squash family predominantly contains linear members. Head-to-tail cyclization is intuitively expected to improve bioactivities by increasing stability and lowering flexibility as well as sensitivity to proteolytic attack. Results In this paper, we report data on solution structure, thermal stability, and flexibility as inferred from NMR experiments and molecular dynamics simulations of a linear squash inhibitor EETI-II, a circular squash inhibitor MCoTI-II, and a linear analog lin-MCoTI. Strikingly, the head-to-tail linker in cyclic MCoTI-II is by far the most flexible region of all three compounds. Moreover, we show that cyclic and linear squash inhibitors do not display large differences in structure or flexibility in standard conditions, raising the question as to why few squash inhibitors have evolved into cyclic compounds. The simulations revealed however that the cyclization increases resistance to high temperatures by limiting structure unfolding. Conclusion In this work, we show that, in contrast to what could have been intuitively expected, cyclization of squash inhibitors does not provide clear stability or flexibility modification. Overall, our results suggest that, for squash inhibitors in standard conditions, the circularization impact might come from incorporation of an additional loop sequence, that can contribute to the miniprotein specificity and affinity, rather than from an increase in conformational rigidity

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

    OpenAIRE

    Piiparinen, Jonna

    2011-01-01

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

  20. Liquefaction-fluidization induced land subsidence: impact of the 2011 Tohoku earthquake on reclaimed land around Tokyo bay area, Japan

    OpenAIRE

    A. Kagawa; Furuno, K; Kusuda, T.; Sakai, Y.; Yoshida, T.; Kazaoka, O.

    2015-01-01

    The 2011 Tohoku earthquake caused major liquefaction-induced, ground deformation of the reclaimed land surrounding Tokyo Bay. In this area, liquefaction was visibly manifest by sand boils, ejection of sandy water, land subsidence and floating underground tanks. The level measurements show a correspondence between the degree of liquefaction-fluidization and the amount of subsidence. The strata most susceptible to liquefaction are hydraulically emplaced dredged fill and artifi...

  1. An evaluation of temporal changes in sediment accumulation and impacts on carbon burial in Mobile Bay, Alabama, USA

    Science.gov (United States)

    Smith, Christopher G.; Osterman, Lisa E.

    2014-01-01

    The estuarine environment can serve as either a source or sink of carbon relative to the coastal ocean carbon budget. A variety of time-dependent processes such as sedimentation, carbon supply, and productivity dictate how estuarine systems operate, and Mobile Bay is a system that has experienced both natural and anthropogenic perturbations that influenced depositional processes and carbon cycling. Sediments from eight box cores provide a record of change in bulk sediment accumulation and carbon burial over the past 110 years. Accumulation rates in the central part of the basin (0.09 g cm−2) were 60–80 % less than those observed at the head (0.361 g cm−2) and mouth (0.564 g cm−2) of the bay. Sediment accumulation in the central bay decreased during the past 90 years in response to both anthropogenic (causeway construction) and natural (tropical cyclones) perturbations. Sediment accumulation inevitably increased the residence time of organic carbon in the oxic zone, as observed in modeled remineralization rates, and reduced the overall carbon burial. Such observations highlight the critical balance among sediment accumulation, carbon remineralization, and carbon burial in dynamic coastal environments. Time-series analysis based solely on short-term observation would not capture the long-term effects of changes in sedimentation on carbon cycling. Identifying these relationships over longer timescales (multi-annual to decadal) will provide a far better evaluation of coastal ocean carbon budgets.

  2. Ocean currents structuring the mesozooplankton in the Gulf of Mannar and the Palk Bay, southeast coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Jagadeesan, L.; Jyothibabu, R.; Anjusha, A.; Mohan, A.P.; Madhu, N.V.; Muraleedharan, K.R.; Sudheesh, K.

    We hypothesis perceptible physical barriers that exist between the deep Gulf of Mannar and shallow Palk Bay located between India and Sri Lanka, and seasonally reversing surface circulation patterns in the region have a concerted effect...

  3. Migration studies and stock structure of dolly varden in the Chiniak Bay area of Kodiak Island, Alaska: Draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — From 1984 through 1989 a total of 31,374 Dolly Varden (Salvelinus malma) in the Chiniak Bay area of Kodiak Island, Alaska were tagged with numbered anchor tags....

  4. Structural aspects of the surf-zone fish assemblage at King's Beach, Algoa Bay, South Africa: Long-term fluctuations

    Science.gov (United States)

    Lasiak, Theresa A.

    1984-04-01

    Regular collections of fish were obtained from the surf-zone at King's Beach, Algoa Bay. A total of 3970 fish, representing 50 species was caught with a coarse net and 16 857 fish, representing 37 species, were caught with a fine net. Predominant species were the blacktail, Diplodus sargus; the sand steenbras, Lithognathus mormyrus; the mullet, Liza richardsoni; the gorrie, Pomadasys olivaceum; the white stumpnose, Rhabdosargus globiceps; the sandshark, Rhinobatos annulatus; and the streepie, Sarpa salpa. No seasonal trends were discernible in the overall abundance or species diversity. The species composition of the dominant component of the fish assemblage varied considerably. This indicated instability in the community structure and cast doubts on the applicability of a classic community concept and the use of diversity indices. Neither classification nor correspondence analysis were of any use in identifying a characteristic species component. Multiple regression analysis indicated that short-term variations in wind conditions might be a primary determinant of fluctuations in abundance. The lack of seasonality in the community parameters may reflect the fact that short-term variability masks seasonal perturbations.

  5. A study on the structure of the convective atmosphere over the Bay of Bengal during BOBMEX-99

    Indian Academy of Sciences (India)

    U C Mohanty; N V Sam; S Das; A N V Satyanarayana

    2003-06-01

    Convective activity is one of the major processes in the atmosphere influencing the local and large scale weather in the tropics. The latent heat released by the cumulus cloud is known to drive monsoon circulation, which on the other hand supplies the moisture that maintains the cumulus clouds. An investigation is carried out on the convective structure of the atmosphere during active and suppressed periods of convection using data sets obtained from the Bay of Bengal and Monsoon Experiment (BOBMEX). The cumulus convection though being a small-scale phenomenon, still influences its embedding environment by interaction through various scales. This study shows the variation in the kinematic and convective parameters during the transition from suppressed to active periods of convection. Convergence in the lower levels and strong upward vertical velocity, significant during active convection are associated with the formation of monsoon depressions. The apparent heat source due to latent heat release and the vertical transport of the eddy heat by cumulus convection, and the apparent moisture sink due to net condensation and vertical divergence of the eddy transport of moisture, are estimated through residuals of the thermodynamic equation and examined in relation to monsoon activity during BOBMEX.

  6. Atmospheric Forcing and the Structure and Evolution of the Upper Ocean in the Bay of Bengal

    Science.gov (United States)

    2015-09-30

    blue ) and sea surface salinity (brown) overplotted. The impact of the two monsoons on the surface forcing is evident in the wind rose (Figure 3...System 1 on the buoy at 18°N, 89°E. From the top, the panels are: wind speed, wind direction, air temperature ( blue ) and sea surface temperature...red) overplotted, relative humidity, incoming shortwave radiation ( blue ) and incoming longwave radiation (brown) overplotted, and rain gauge level

  7. Microbial biogeography of San Francisco Bay sediments

    Science.gov (United States)

    Lee, J. A.; Francis, C. A.

    2014-12-01

    The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess

  8. The Impact of Structural Genomics: Expectations and Outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Chandonia, John-Marc; Brenner, Steven E.

    2005-12-21

    Structural Genomics (SG) projects aim to expand our structural knowledge of biological macromolecules, while lowering the average costs of structure determination. We quantitatively analyzed the novelty, cost, and impact of structures solved by SG centers, and contrast these results with traditional structural biology. The first structure from a protein family is particularly important to reveal the fold and ancient relationships to other proteins. In the last year, approximately half of such structures were solved at a SG center rather than in a traditional laboratory. Furthermore, the cost of solving a structure at the most efficient U.S. center has now dropped to one-quarter the estimated cost of solving a structure by traditional methods. However, top structural biology laboratories are much more efficient than the average, and comparable to SG centers despite working on very challenging structures. Moreover, traditional structural biology papers are cited significantly more often, suggesting greater current impact.

  9. Current structure and volume transport across 12 degrees N in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Suryanarayana, A.; Rao, D.P.

    of India from April to September. Current structure in November is similar to that in September with a shift in the current bands. Transport in the upper 1000 m between the stations exhibits a reversal west of 83 degrees E from April to September and east...

  10. Differential metallothionein, reduced glutathione and metal levels in Perna perna mussels in two environmentally impacted tropical bays in southeastern Brazil.

    Science.gov (United States)

    Lavradas, Raquel T; Rocha, Rafael C C; Bordon, Isabella C A C; Saint'Pierre, Tatiana D; Godoy, José M; Hauser-Davis, Rachel A

    2016-07-01

    Mussel farming is an important economic activity in Brazil, and these organisms are consumed by the majority of the population in most coastal zones in the country. However, despite the increasing pollution of aquatic ecosystems in Brazil, little is known about the biochemical activity in mussels in response to metal exposure. In this context, the aim of the present study was to investigate metal and metalloid exposure effects in Perna perna mussels, by determining metal levels, the induction of metallothionein (MT) synthesis, and oxidative stress, in the form of reduced glutathione (GSH) in 3 contaminated areas from the Guanabara Bay in comparison to a reference site, Ilha Grande Bay, both in summer and winter. Metal and metalloid concentrations were also compared to Brazilian and international guidelines, to verify potential health risks to human consumers. Mussels from all sampling sites were shown to be improper for human consumption due to metal contamination, including Ilha Grande Bay, which has previously been considered a reference site. Several statistically significant correlations and seasonal differences were observed between MT, GSH and metals and metalloids in both analyzed tissues. A Discriminant Canonical Analysis indicated that the digestive gland is a better bioindicator for environmental contamination by metals and metalloids in this species and offers further proof that MT variations observed are due to metal exposure and not oxidative stress, since GSH influence for both muscle tissue and the digestive glands was non-significant in this analysis. These results show that P. perna mussels are an adequate sentinel species for metal contamination with significant effects on oxidative stress and metal exposure biomarkers. To the best of our knowledge, this is the first study to report metals, metalloids, MT and GSH levels in the muscle tissue of this species.

  11. The impact of large-scale reclamation on hydro-dynamic environment-A case study of Xinghua Bay

    Science.gov (United States)

    Yu, Jing; Bao, Xianwen; Ding, Yang; Zhang, Wei; Zhou, Lingling

    2016-08-01

    A hydro-dynamic model is established on basis of MIKE21FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. Tidal elevation data was obtained at the six tide gauge stations around the Xinghua Bay, and another six current stations were established to observe the tidal current velocity and direction. Validation shows that the model-simulated tidal elevation and tidal currents agree well with observations made at different stations. Predictions are made according to the reclamation project proposed in the regional marine planning of Hanjiang Industrial Park around the port in Putian City. The variations of hydro-dynamic factors, such as tide, current velocity and direction and tidal influx are obtained, and the adverse effect of reclamation on marine environment is discussed. It is shown that the tidal level inside the Xinghua Bay during high tide decreases after the reclamation project is completed. The tidal currents during flooding tide generally decrease in the southeast of the reclamation region, with the maximum decreasing amplitude reaching 0.44 m s-1. On the other hand, the tidal currents during flooding tide increase around the southeast and southwest corners of the reclamation region. The tidal currents during ebb tide increase around the southeast and southwest corners of the reclamation region, with the maximum increasing amplitude attaining 0.18 m s-1. The results in this paper can give some guidance for the marine environment management and the effective utilization of land in Putian.

  12. Stratigraphic and Structural Characteristics of the Santa Marta Impact Structure, Brazil

    Science.gov (United States)

    Oliveira, G. J. G.; Chamani, M.; Góes, A. M.; Crósta, A. P.; Vasconcelos, M. A. R.; Reimold, W. U.

    2016-08-01

    Santa Marta structure is a moderate-size complex impact structure formed in sedimentary targets, Brazil. We provide an overview of the stratigraphy and deformation patterns of the strata identified within the structure.

  13. Impact Structures: What Does Crater Diameter Mean?

    Science.gov (United States)

    Turtle, E. P.; Pierazzo, E.; Collins, G. S.; Osinski, G. R.; Melosh, H. J.; Morgan, J. V.; Reimold, W. U.; Spray, J. G.

    2004-03-01

    Crater diameter is an important parameter in energy scaling and impact simulations. However, disparate types of data make the use of consistent metrics difficult. We suggest a consistent terminology and discuss it in the context of several examples.

  14. Liquefaction-fluidization induced land subsidence: impact of the 2011 Tohoku earthquake on reclaimed land around Tokyo bay area, Japan

    Science.gov (United States)

    Kagawa, A.; Furuno, K.; Kusuda, T.; Sakai, Y.; Yoshida, T.; Kazaoka, O.

    2015-11-01

    The 2011 Tohoku earthquake caused major liquefaction-induced, ground deformation of the reclaimed land surrounding Tokyo Bay. In this area, liquefaction was visibly manifest by sand boils, ejection of sandy water, land subsidence and floating underground tanks. The level measurements show a correspondence between the degree of liquefaction-fluidization and the amount of subsidence. The strata most susceptible to liquefaction are hydraulically emplaced dredged fill and artificial strata on thick uncompacted Holocene deposits. On the other hand, the phenomena of seismic isolation coursed by liquefaction had saved the single-family houses from collapse.

  15. Picosecond to second dynamics reveals a structural transition in Clostridium botulinum NO-sensor triggered by the activator BAY-41-2272.

    Science.gov (United States)

    Yoo, Byung-Kuk; Lamarre, Isabelle; Rappaport, Fabrice; Nioche, Pierre; Raman, C S; Martin, Jean-Louis; Negrerie, Michel

    2012-12-21

    Soluble guanylate cyclase (sGC) is the mammalian endogenous nitric oxide (NO) receptor that synthesizes cGMP upon NO activation. In synergy with the artificial allosteric effector BAY 41-2272 (a lead compound for drug design in cardiovascular treatment), sGC can also be activated by carbon monoxide (CO), but the structural basis for this synergistic effect are unknown. We recorded in the unusually broad time range from 1 ps to 1 s the dynamics of the interaction of CO binding to full length sGC, to the isolated sGC heme domain β(1)(200) and to the homologous bacterial NO-sensor from Clostridium botulinum. By identifying all phases of CO binding in this full time range and characterizing how these phases are modified by BAY 41-2272, we show that this activator induces the same structural changes in both proteins. This result demonstrates that the BAY 41-2272 binding site resides in the β(1)(200) sGC heme domain and is the same in sGC and in the NO-sensor from Clostridium botulinum.

  16. Mitigation of Shore Damage Attributed to the Federal Navigation Structures at Hammond Bay Harbor.

    Science.gov (United States)

    1976-11-01

    equipment would enter or exit the irea via U.S. Route 23. This additional traffic and its attezding wear and tear to the roadway structure can be expected...National Climatic Cen--27, AivleNorth Carolina 28801. C- ’ L - - L "aa. H1!41w1WU O CCM’.:,ERCE i’𔃽iai Ocean ic and Atmospheric Administracion Ann Arb,-r

  17. The cumulative impacts of repeated heavy rainfall, flooding and altered water quality on the high-latitude coral reefs of Hervey Bay, Queensland, Australia.

    Science.gov (United States)

    Butler, I R; Sommer, B; Zann, M; Zhao, J-X; Pandolfi, J M

    2015-07-15

    Terrestrial runoff and flooding have resulted in major impacts on coral communities worldwide, but we lack detailed understanding of flood plume conditions and their ecological effects. Over the course of repeated flooding between 2010 and 2013, we measured coral cover and water quality on the high-latitude coral reefs of Hervey Bay, Queensland, Australia. In 2013, salinity, total suspended solids, total nitrogen and total phosphorus were altered for up to six months post-flooding. Submarine groundwater caused hypo-saline conditions for a further four months. Despite the greater magnitude of flooding in 2013, declines in coral abundance (∼28%) from these floods were lower than the 2011 flood (∼40%), which occurred immediately after a decade of severe drought. There was an overall cumulative decrease of coral by ∼56% from 2010 to 2013. Our study highlights the need for local scale monitoring and research to facilitate informed management and conservation of catchments and marine environments.

  18. Fine-scale population structure of two anemones (Stichodactyla gigantea and Heteractis magnifica) in Kimbe Bay, Papua New Guinea

    KAUST Repository

    Gatins, Remy

    2014-12-01

    Anemonefish are one of the main groups that have been used over the last decade to empirically measure larval dispersal and connectivity in coral reef populations. A few species of anemones are integral to the life history of these fish, as well as other obligate symbionts, yet the biology and population structure of these anemones remains poorly understood. The aim of this study was to measure the genetic structure of these anemones within and between two reefs in order to assess their reproductive mode and dispersal potential. To do this, we sampled almost exhaustively two anemones species (Stichodactyla gigantea and Heteractis magnifica) at two small islands in Kimbe Bay (Papua New Guinea) separated by approximately 25 km. Both the host anemones and the anemonefish are heavily targeted for the aquarium trade, in addition to the populations being affected by bleaching pressures (Hill and Scott 2012; Hobbs et al. 2013; Saenz- Agudelo et al. 2011; Thomas et al. 2014), therefore understanding their biology is crucial for better management strategies. Panels of microsatellite markers were developed for each species using next generation sequencing tools. Clonality analyses confirm six pairs of identical genotypes for S. gigantea (n=350) and zero for H. magnifica (n=128), indicating presence/absence of asexual reproduction in this region. S. gigantea showed low structure between islands (FST= 0.003, p-value= 0.000), however, even if the majority of the individuals were unrelated (r~0), 81 families that shared 50% of their genetic material formed from two to four members were found. Out of these families, 45% were found with individuals only within Tuare Island, 11% only in Kimbe Island, and 44% were sharing individuals among islands. In comparison, H. magnifica showed no structure (FST= 0.002, p-value= 0.278), mean relatedness indicated the majority of individuals were unrelated, and 31 families were identified. Families again consisted from two to four members and

  19. Distribution and community structure of fish in Obitsu-gawa River Estuary of inner Tokyo Bay, central Japan

    Directory of Open Access Journals (Sweden)

    Joeppette J. Hermosilla

    2012-09-01

    Full Text Available The distribution and community structure of fish in Obitsu-gawa River Estuary of inner TokyoBay, central Japan was studied from May to December 2005 and March to April 2006. A total of 19,006individuals, represented by 25 species and some unidentified species under family Clupeidae, Cyprinidae,Gobiidae, Hemiramphidae, Mugilidae, Platycephidae, Pleuronectidae and Triglidae were collected. FamilyGobiidae had the most number of taxa with 13 genera and 10 species. Greatest fish abundancehappened in August and secondarily in April and May. Species richness was evident in the warmermonths particularly in May (17 taxa, August (21 taxa, September (15 taxa and October (17 taxa.Marine teleosts significantly contributed to the species richness and abundance of fish, whichcorresponded to 52.9% (10,046 individuals of the total catch while the estuarine fishes were the secondmost abundant group with 33.5% (6,372 individuals of the total catch. Species dominance was acoherent feature of this community. The proportional contribution of marine teleosts to the fishcommunity decreased with increase distance upstream while that of estuarine fishes increased withincrease distance upstream. The developmental stages of gobies range from larvae to adult but juvenilesconstitute 77.06% of the total sample. The distribution of developmental stage of estuarine gobies wasinfluenced to a greater extent by variation in monthly water temperature and station or the interaction ofboth. Adult estuarine gobies had the tendency to aggregate in the middle estuary reflecting their hightolerance to a wide range of water salinity inherent in this station but avoided the lower estuary mostlikely due to the predominance of high salinity waters.

  20. The two Suvasvesi impact structures, Finland: Argon isotopic evidence for a "false" impact crater doublet

    Science.gov (United States)

    Schmieder, Martin; Schwarz, Winfried H.; Trieloff, Mario; Buchner, Elmar; Hopp, Jens; Tohver, Eric; Pesonen, Lauri J.; Lehtinen, Martti; Moilanen, Jarmo; Werner, Stephanie C.; Öhman, Teemu

    2016-05-01

    The two neighboring Suvasvesi North and South impact structures in central-east Finland have been discussed as a possible impact crater doublet produced by the impact of a binary asteroid. This study presents 40Ar/39Ar geochronologic data for impact melt rocks recovered from the drilling into the center of the Suvasvesi North impact structure and melt rock from glacially transported boulders linked to Suvasvesi South. 40Ar/39Ar step-heating analysis yielded two essentially flat age spectra indicating a Late Cretaceous age of ~85 Ma for the Suvasvesi North melt rock, whereas the Suvasvesi South melt sample gave a Neoproterozoic minimum (alteration) age of ~710 Ma. Although the statistical likelihood for two independent meteorite strikes in close proximity to each other is rather low, the remarkable difference in 40Ar/39Ar ages of >600 Myr for the two Suvasvesi impact melt samples is interpreted as evidence for two temporally separate, but geographically closely spaced, impacts into the Fennoscandian Shield. The Suvasvesi North and South impact structures are, thus, interpreted as a "false" crater doublet, similar to the larger East and West Clearwater Lake impact structures in Québec, Canada, recently shown to be unrelated. Our findings have implications for the reliable recognition of impact crater doublets and the apparent rate of binary asteroid impacts on Earth and other planetary bodies in the inner solar system.

  1. Thermohaline structure and circulation in the upper layers of the southern Bay of Bengal during BOBMEX-Pilot (October — November 1998)

    Indian Academy of Sciences (India)

    V Ramesh Babu; V S N Murty; L V G Rao; C V Prabhu; V Tilvi

    2000-06-01

    Hydrographic data collected on board ORV Sagar Kanya in the southern Bay of Bengal during the BOBMEX-Pilot programme (October - November 1998) have been used to describe the thermohaline structure and circulation in the upper 200 m water column of the study region. The presence of seasonal Inter-Tropical Convergence Zone (ITCZ) over the study area, typically characterized with enhanced cloudiness and flanked by the respective east/northeast winds on its northern part and west/southwest winds on its southern part, has led to net surface heat loss of about 55 W/m2. The sea surface dynamic topography relative to 500 db shows that the upper layer circulation is characterised by a cyclonic gyre encompassing the study area. The eastward flowing Indian Monsoon Current (IMC) between 5° N and 7° N in the south and its northward branching along 87° E up to 13° N appear to feed the cyclonic gyre. The Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents confirm the presence of the cyclonic gyre in the southern Bay of Bengal during the withdrawing phase of the southwest monsoon from the northern/central parts of the Bay of Bengal.

  2. Distribution and structure of zooplankton communities in the austral summer in the Prydz Bay, Antarctica

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    As a structure linking the ecosystem and population, community plays an important role in the marine ecology. Abundance of different species and development stages were used in our classification to the sampling stations with clustering-analysis and multi-dimension scaling, through which three geographic communities were marked out, respectively as following: the Salp community characterized by presence of Salp thompni in the northern area, the Near-shore community by Euphausia crystallorophias in the south and the main ocean community located between the above two communities. Indicator species method was then carried out between every two communities to findout which species or stages differ most. It tells that Rhincalanus gigas, adult cheatognath, late stages of Metridia gerlachei and calyptopis of Euphausiidae are indicators between Salp and neritic communities, between Krill and Salp communities are Salp thompni, adult and larvae of Cheatognath and R. gigas, and the most notable indicator between the Krill and the neritic communities are E. crystallorophias, then nauplii of Euphausiidae and Onceae conifera with less evidence.

  3. Geophysical and structural criteria for the identification of buried impact structures, with reference to Australia

    Science.gov (United States)

    Glikson, Andrew; Uysal, I. Tonguç

    2013-10-01

    The discovery of large asteroid impact structures, likely and possible impact structures, onshore and offshore the Australian continent (Woodleigh [120 km; ~ 360 Ma], Gnargoo [75 km; Lower Permian — upper Cretaceous], Tookoonooka [55-65 km; ~ 125 Ma], Talundilly [~ 84 km; ~ 125 Ma], Mount Ashmore [> 100 km; end-Eocene] and Warburton twin structures [> 400 km; pre-end Carboniferous]) requires re-examination of the diagnostic criteria used for their identification. Bouguer anomalies of established impact structures (Chicxulub [170 km; 64.98 ± 0.05 Ma], Woodleigh impact structure and Gnargoo probable impact structure display a unique structural architecture where pre-impact structural ridges are intersected and truncated by the outer ring of the circular structure. Seismic reflection data outline circular central uplift domes, basement plugs and rim synclines. Sharp circular seismic tomography anomalies indicate low velocity columns under both the Woodleigh impact structure and Warburton probable impact, hinting at deep crustal fracturing. Deformed, curved and clouded intra-crystalline planar deformation features in quartz (Qz/PDFs), displaying Miller indices ({10-11}, {10-12}, {10-13}) diagnostic of shock metamorphism, abound around exposed established impact structures (Vredefort [298 km; 2023 ± 4 Ma], Sudbury [~ 250 km; 1850 ± 3 Ma], Charlevoix [54 km; 342 ± 15 Ma], Manicouagan [100 km; 214 ± 1 Ma]), Tookoonooka and Talundilly). Deformed Qz/PDFs allow recognition of shock metamorphism in buried impact structures, where original Qz/PDFs were bent, recrystallized and/or clouded during formation of the central uplift and hydrothermal activity triggered by the impact. Planar deformation in quartz can also occur in explosive pyroclastic units but are limited to Boehm lamella (Brazil twins) with single lamella sets {0001}. It has been suggested that a class of microstructures in quartz, referred to as metamorphic deformation lamella (Qz/MDL), occur in endogenic

  4. Intensity of the Trough over the Bay of Bengal and Its Impact on the Southern China Precipitation in Winter

    Institute of Scientific and Technical Information of China (English)

    ZONG Hai-Feng; BUEH Cholaw; WEI Jie; CHEN Lie-Ting

    2012-01-01

    In this study, the intensity of the trough over the Bay of Bengal (BBT) and its association with the southern China precipitation, the Madden-Julian Oscillation (MJO) and the Rossby wave propagation along the African-Asian subtropical Jet stream (AASJ) are investigated on the intraseasonal time scale. The results show that the intensity of the BBT affects the southern China precipitation more directly and to a greater degree than the MJO. The peak amplitude of the BBT tended to occur in phase-3 of the MJO. The strong BBT was substantially modulated by the Rossby wave propagation along the AASJ, which was triggered by the anomalous upstream circulation similar to the pattern of the North Atlantic Oscillation (NAO). Therefore, from the perspective of medium- and extended-range weather forecasts, the NAO- like pattern may be regarded as a precursory signal for the strong BBT and thus the southern China precipitation.

  5. Impact of a river system on carbon sedimentation and sequestration in Cook's Bay of Lake Simcoe, Ontario

    Science.gov (United States)

    Blodau, Christian; Agethen, Svenja; Spangenberg, Ines; Broder, Tanja; Gimbel, Nicole; Strauss, Harald; Knorr, Klaus-Holger

    2016-04-01

    The influence of sedimentation rates and organic matter quality on carbon sequestration and mineralization at the land-water interface of lakes is not well understood. To study this issue we investigated shallow Cook's Bay of temperate Lake Simcoe in southern Ontario. The elongated bay provides gradients in morphometry, trophic level, and distance to a major tributary as a potential point source of nutrients and terrestrial organic carbon. At five sampling sites of increasing distance to the river outlet the water column was examined during stratification regarding physio-chemical parameters, dissolved organic matter (DOM) characteristics, sedimentation rates and mineralization of settling material and sediments. To quantify actual organic carbon burial, sedimentation rates and mineralization were determined in situ and by diffusive flux modeling. Long-term carbon burial and sedimentation rates were determined using 210Pb dated sediment cores. Organic carbon quality and origin were analyzed in water samples via fluorescence spectroscopy, solid DOM and settling particles via elemental analysis and 13C isotopic data. Results showed that actual and long-term carbon burial were highest at the central sites of the transect (52-63%) and lowest at the profundal sites (0-25%). Current organic carbon deposition was highest near the river outlet (max. 0.3 g C m-2 d-1) and there the settling material reaching the sediments and in the sediments was also most highly decomposable. Total sedimentation rates and organic carbon burial were closely related. Compared to the outer sites, the DOM quality was significantly different at the site closest to the river outlet but already strongly influenced by lacustrine carbon cycling. Permanent organic carbon burial was mainly influenced by sedimentation related to lake morphometry and dependent parameters. The relation between sedimentation and carbon burial rates underlined the importance of oxygen exposure time and burial for

  6. Impact of Technology on Management Structure

    OpenAIRE

    Glushkov, L.; Razvigorova, E.

    1988-01-01

    The problem of type, characteristics, and factors which influence organizational structure has always been a basic problem in management, both for researchers and for managers. Organizational structure, in addition to being a management tool, is also an expression of power and social status, and this obviously makes it an attractive problem for everyone. In management literature, particularly in the literature on the management of innovation processes, there are few studies more numerous than...

  7. Application of a Structured Decision Process for Informing Watershed Management Options in Guánica Bay, Puerto Rico

    Science.gov (United States)

    The Guánica Bay watershed has been a priority for research, assessment and management since the 1970s, and since 2008, has been the focus of a U.S. Coral Reef Task Force (USCRTF) research initiative involving multiple agencies assembled to address the effect of land management de...

  8. Biogeochemical redox cycling of arsenic in mine-impacted lake sediments and co-existing pore waters near Giant Mine, Yellowknife Bay, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, C.F. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Jamieson, H.E., E-mail: jamieson@geol.queensu.ca [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Kyser, T.K. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Praharaj, T.; Fortin, D. [University of Ottawa, Department of Earth Sciences, Ottawa, K1A 3N5 (Canada)

    2010-02-15

    Lacustrine sediments, submerged tailings, and their pore waters have been collected at several sites in Yellowknife Bay, Great Slave Lake, Canada, in order to investigate the biogeochemical controls on the remobilization of As from mining-impacted materials under different depositional conditions. Radiometric dating confirms that a mid-core enrichment of Pb, Zn, Cu and Sb corresponds to the opening of a large Au mine 60 a ago. This was evident even in a relatively remote site. Arsenic was enriched at mid-core, coincident with mining activity, but clearly exhibited post-depositional mobility, migrating upwards towards the sediment water interface (SWI) as well as down-core. Deep-water (15 m) Yellowknife Bay sediments that contain buried mine waste are suboxic, relatively organic-rich and abundant in microbes with As in pore waters and sediments reaching 585 {mu}g/L and 1310 mg/kg, respectively. Late summer pore waters show equal proportions of As(III) and As(V) (16-415 {mu}g/L) whereas late winter pore waters are dominated by As(III) (284-947 {mu}g/L). This can be explained by As(III) desorption mechanisms associated with the conversion of FeS to FeS{sub 2} and the reduction of As(V) to As(III) through the oxidation of dissolved sulfide, both microbially-mediated processes. Processes affecting As cycling involve the attenuating efficiency of the oxic zone at the SWI, sediment redox heterogeneity and the reductive dissolution of Fe(hydr)oxides by labile organic matter, temporarily and spatially variable.

  9. Study of Similarity Law for Bird Impact on Structure

    Institute of Scientific and Technical Information of China (English)

    Li Yulong; Zhang Yongkang; Xue Pu

    2008-01-01

    With dimensional analysis and similarity theory, the model similarity law of aircraft structures under bird impact load is investi-gated. Numerical calculations by means of nonlinear dynamic software ANSYS/LS-DYNA are conducted on the finite element models constructed with different scaling factors. The influence of strain rate on the model similarity law is found to be dependent on the swain rate sensitivity of materials and scale factors. Specifically, materials that are not sensitive to strain rate obey the model similarity law in the bird impact process. The conclusions obtained are supposed to provide a theoretical basis for the experimental work of bird impact on aircraft structure.

  10. Mjolnir structure: An impact crater in the Barents Sea

    Energy Technology Data Exchange (ETDEWEB)

    Dypvik, H.; Gudlaugsson, S.T.; Tsikalas, F.; Faleide, J.I.; Nagy, J. [Univ. of Oslo (Norway); Attrep, M. Jr. [Los Alamos National Lab., NM (United States); Ferrell, R.E. Jr. [Louisiana State Univ., Baton Rouge, LA (United States); Krinsley, D.H. [Univ. of Oregon, Eugene, OR (United States); Mork, A. [IKU Petroleum Research, Trondheim (Norway)

    1996-09-01

    A systematic search for impact indicators was conducted on a core of Late Jurassic-Early Cretaceous sedimentary strata from the vicinity of the proposed Mjolnir impact structure, Barents Sea. A 0.8 m-thick section of the core was found to contain unequivocal indicators of meteoritic impact: shocked quartz grains and a strong enrichment in iridium. The ejecta-bearing strata were discovered only 30 km north-northeast of the structure, within a stratigraphic interval corresponding to the seismically defined deformation event at Mjolnir. Further study of this unusually well presented impact-crater-ejecta-layer pair may help constrain poorly understood aspects of large-magnitude meteorite impacts into the oceans. 14 refs., 4 figs.

  11. A numerical study on the impact of tidal waves on the storm surge in the north of Liaodong Bay

    Institute of Scientific and Technical Information of China (English)

    KONG Xiangpeng

    2014-01-01

    A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system. A storm tide is a water level rise or fall caused by the com-bined effect of the storm surge and an astronomical tide. The storm surge depends on many factors, such as the tracks of typhoon movement, the intensity of typhoon, the topography of sea area, the amplitude of tidal wave, the period during which the storm surge couples with the tidal wave. When coupling with different parts of a tidal wave, the storm surges caused by a typhoon vary widely. The variation of the storm surges is studied. An once-in-a-century storm surge was caused by Typhoon 7203 at Huludao Port in the north of the Liaodong Bay from July 26th to 27th, 1972. The maximum storm surge is about 1.90 m. The wind field and pressure field used in numerical simulations in the research were derived from the historical data of the Typhoon 7203 from July 23rd to 28th, 1972. DHI Mike21 is used as the software tools. The whole Bohai Sea is defined as the computational domain. The numerical simulation models are forced with sea levels at water boundaries, that is the tide along the Bohai Straits from July 18th to 29th (2012). The tide wave and the storm tides caused by the wind field and pressure field mentioned above are calculated in the numerical simulations. The coupling processes of storm surges and tidal waves are simulated in the following way. The first simulation start date and time are 00:00 July 18th, 2012;the second simulation start date and time are 03:00 July 18th, 2012. There is a three-hour lag between the start date and time of the simulation and that of the former one, the last simulation start date and time are 00:00 July 25th, 2012. All the simulations have a same duration of 5 days, which is same as the time length of typhoon data. With the first day and the second day simulation output, which is affected by the initial field, being

  12. The San Andreas fault in the San Francisco Bay region, California: Structure and kinematics of a Young plate boundary

    Science.gov (United States)

    Jachens, R.C.; Zoback, M.L.

    1999-01-01

    Recently acquired high-resolution aeromagnetic data delineate offset and/or truncated magnetic rock bodies of the Franciscan Complex that define the location and structure of, and total offset across, the San Andreas fault in the San Francisco Bay region. Two distinctive magnetic anomalies caused by ultramafic rocks and metabasalts east of, and truncated at, the San Andreas fault have clear counterparts west of the fault that indicate a total right-lateral offset of only 22 km on the Peninsula segment, the active strand that ruptured in 1906. The location of the Peninsula segment is well defined magnetically on the northern peninsula where it goes offshore, and can be traced along strike an additional ~6 km to the northwest. Just offshore from Lake Merced, the inferred fault trace steps right (northeast) 3 km onto a nearly parallel strand that can be traced magnetically northwest more than 20 km as the linear northeast edge of a magnetic block bounded by the San Andreas fault, the Pilarcitos fault, and the San Gregorio-Hosgri fault zone. This right-stepping strand, the Golden Gate segment, joins the eastern mapped trace of the San Andreas fault at Bolinas Lagoon and projects back onshore to the southeast near Lake Merced. Inversion of detailed gravity data on the San Francisco Peninsula reveals a 3 km wide basin situated between the two strands of the San Andreas fault, floored by Franciscan basement and filled with Plio-Quaternary sedimentary deposits of the Merced and Colma formations. The basin, ~1 km deep at the coast, narrows and becomes thinner to the southeast along the fault over a distance of ~12 km. The length, width, and location of the basin between the two strands are consistent with a pull-apart basin formed behind the right step in the right-lateral strike-slip San Andreas fault system and currently moving southeast with the North American plate. Slight nonparallelism of the two strands bounding the basin (implying a small component of convergence

  13. Experimental Study of Hypervelocity Impact on Multi-Shock Structure

    Institute of Scientific and Technical Information of China (English)

    张庆明; 陈沿海; 黄风雷

    2004-01-01

    Hypervelocity impact tests on multi-shock shields are carried out in order to develop space structures against space debris impacts. Sheets of LY12 aluminum were used as bumpers. The total thickness of shield structure, which consists of several sheets with various thickness, is 3.0 mm or 2.0 mm. Results of the tests show that the type 0.5 mm+0.5 mm+0.5 mm+0.5 mm is a better choice of spacecraft shield structure.

  14. Examining the factor structure of the Multiple Sclerosis Impact Scale.

    Science.gov (United States)

    Fitzgerald, Shawn M; Li, Jian; Rumrill, Phillip D; Merchant, William; Bishop, Malachy

    2014-01-01

    The purpose of this study was to investigate the factor structure of the Multiple Sclerosis Impact Scale (MSIS-29) to assess its suitability for modeling the impact of MS on a nation-wide sample of individuals from the United States. Investigators completed a Confirmatory Factor Analysis (CFA) to examine the two-factor structure proposed by Hobart et al. [17]. Although the original MSIS-29 factor structure did not fit the data exactly, the hypothesized two-factor model was partially supported in the current data. Implications for future instrument development and rehabilitation practice are discussed.

  15. Seasonal pattern and community structure of fishes in the shallow tidal creek of Obitsu-gawa River Estuary of inner Tokyo Bay, central Japan

    Directory of Open Access Journals (Sweden)

    Masato Moteki

    2012-12-01

    Full Text Available Seasonal pattern and the community structure of fishes in the shallow tidal creek of ObitsugawaRiver Estuary of inner Tokyo Bay was studied for one year. Family Gobiidae corresponded to 98%of the total catch. Dominant species were Gymnogobius uchidai, Gymnogobius macrognathos,Gymnogobius breunigii, Eutaeniichthys gilli, Pseudogobius masago and Favonigobius gymnauchen.Stepwise modelling in canonical correspondence analysis indicated that season (p=0.02 best explainedthe variation in abundance of fish in this shallow habitat. There was a difference in fish communitybetween spring and summer while only a small difference was observed between summer and autumn aswell as winter and autumn. Species dominance was an inherent property of the tidal creek fishcommunity particularly in spring because of the remarkable abundance of G. uchidai. However, the fishcommunity had the tendency to become proportionately even as the season progresses from spring towinter. The occurrence of a particular life history stage generally showed a strong association with monthand water temperature. Adults substantially contributed to the population size structure of P. masagoand G. uchidai while juvenile 2 for G. breunigii and E. gilli . Larvae significantly contributed to thepopulation size structure of F. gymnauchen while juvenile 1 and juvenile 2 for G. macrognathos. Thecurrent study indicated that natural shallow habitat within a highly urbanized metropolitan area in innerTokyo Bay can serve as a habitat for fishes and the prevalence of certain life history stages of estuarinespecies indicated the importance of the said habitat at certain part of their life history.

  16. Three-dimensional crustal structure influences on wave propagation and generation of strong ground motion in the greater San Francisco Bay region

    Science.gov (United States)

    Stidham, Christiane Wilson

    Recent development of three-dimensional finite-difference codes allows simulation of earthquakes using realistic three-dimensional earth models. These and other developments have shifted emphasis in seismology from earthquake prediction to estimation of location and magnitude of damage in future earthquakes. The accurate calculation of ground motions for future large earthquakes depends upon detailed knowledge of three-dimensional (3D) geologic structure and the earthquake source process, as well as sufficient computational resources. Knowledge of subsurface geologic structure in the San Francisco Bay Area is quite good relative to many areas, and this knowledge has been incorporated into a 3D velocity model of the Bay Area. With access to a 3D finite-difference code (E3D) developed by Shawn Larsen at Lawrence Livermore National Laboratory and use of super-computing resources at Livermore, we are able to complete calculations for simulations of a number of San Francisco Bay Area earthquakes. These include a small 1993 Rodgers Creek event recorded at Berkeley Seismological Laboratory, the 1989 Loma Prieta event recorded on the U.S. Geological Survey and Calif. Div. of Mines and Geology network of strong motion stations, and a number of small South Bay events (including the 8/12/98 San Juan Bautista EQ) recorded on a temporary USGS/UCB/PASSCAL Santa Clara array. In each of these cases, comparison of synthetic results (synthetic seismograms and plots of maximum horizontal ground velocity) from E3D to recorded data from the event gives an excellent opportunity to both judge the usefulness and the constraints necessary in using finite-difference modeling and the validity of the velocity model as it is now constructed. Results show that 3D finite-difference modeling produces waveforms that are often quite comparable to recorded data, and that fit the data considerably better than synthetics waveforms derived with a 1D velocity model. It is also possible to explore the

  17. Galveston Bay

    Science.gov (United States)

    Handley, Lawrence R.; Spear, Kathryn A.; Eleonor Taylor,; Thatcher, Cindy

    2011-01-01

    The Galveston Bay estuary is located on the upper Texas Gulf coast (Lester and Gonzalez, 2002). It is composed of four major sub-bays—Galveston, Trinity, East, and West Bays. It is Texas’ largest estuary on the Gulf Coast with a total area of 155,399 hectares (384,000 acres) and 1,885 km (1,171 miles) of shoreline (Burgan and Engle, 2006). The volume of the bay has increased over the past 50 years due to subsidence, dredging, and sea level rise. Outside of ship channels, the maximum depth is only 3.7 m (12 ft), with the average depth ranging from 1.2 m (4 ft) to 2.4 m (8 ft)— even shallower in areas with widespread oyster reefs (Lester and Gonzalez, 2002). The tidal range is less than 0.9 m (3 ft), but water levels and circulation are highly influenced by wind. The estuary was formed in a drowned river delta, and its bayous were once channels of the Brazos and Trinity Rivers. Today, the watersheds surrounding the Trinity and San Jacinto Rivers, along with many other smaller bayous, feed into the bay. The entire Galveston Bay watershed is 85,470 km2 (33,000 miles2 ) large (Figure 1). Galveston Island, a 5,000 year old sand bar that lies at the western edge of the bay’s opening into the Gulf of Mexico, impedes the freshwater flow of the Trinity and San Jacinto Rivers into the Gulf, the majority of which comes from the Trinity. The Bolivar Peninsula lies at the eastern edge of the bay’s opening into the Gulf. Water flows into the Gulf at Bolivar Roads, 1 U.S. Geological Survey National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, LA 70506 2 Harte Research Institute for Gulf of Mexico Studies, Texas A&M University - Corpus Christi, 6300 Ocean Drive, Unit 5869, Corpus Christi, Texas 78412 2 Galveston Pass, between Galveston Island and Bolivar Peninsula, and at San Luis Pass, between the western side of Galveston Island and Follets Island.

  18. Potential Impacts of Paleohydrological Changes on Holocene Methane Fluxes in Boreal and Subarctic Peatlands, James Bay, Quebec, Canada

    Science.gov (United States)

    Garneau, M.; Ali, A.; Tremblay, L.; Pelletier, L.; Asnong, H.

    2008-12-01

    In boreal and subarctic region of the La Grande river watershed, James Bay, Quebec, Canada, peatlands cover closed to 15 % of the terrestrial surface. Multi proxy analysis results (plant macrofossils and Testate amoebae) from minerotrophic peatland have demonstrated important variations on the regional water table position since peat started to accumulate in the region ca 7400 cal BP. Macrofossil assemblages indicate that sites were first colonized by black spruce (Picea mariana Ait Muhl.) and Sphagnum spp which paludified with a regional rise of moisture at approx. 4500 BP. Drier conditions registered around 3900 cal BP induced a shift in vegetation and Testate amoeba assemblages for a relatively short period which was followed at approximately 3000 cal BP by an important increase in moisture. This shift in hydrological conditions involved drastic changes in the vegetation cover from Picea mariana and Sphagnum fuscum assemblages to sedges (Carex spp.) and wet Sphagnum species such as S. majus, S. subsecundum, S. pulchrum. This rise in the water table position could have induced enhance methane release to the atmosphere when considering the present-day methane fluxes/water table depth/vegetation cover relationship.

  19. Governance structures impact on eHealth

    DEFF Research Database (Denmark)

    Kierkegaard, Patrick

    2015-01-01

    Background National eHealth implementation efforts need to move beyond the scope of making technology the primary focus and instead consider the broader spectrum of influences that can either hinder or facilitate eHealth adoption such as governance structures and policies. In this study, Denmark...... to identify relevant papers. Results This study reveals that despite Denmark׳s high deployment of eHealth technologies, the Danish healthcare system faces significant interoperability challenges which stem from the country׳s decentralized and centralized approach to eHealth implementation. Conclusion...

  20. Gravity survey of the Mt. Toondina impact structure, South Australia

    Science.gov (United States)

    Plescia, J. B.; Shoemaker, E. M.; Shoemaker, C. S.

    1991-06-01

    The Mt. Toondina impact structure is located in northern South Australia, about 45 km south of the town of Oodnadatta. Only the central uplift is exposed. The outcrops at Mt. Toondina reveal a remarkable structural anomaly surrounded by a broad expanse of nearly flat-lying beds of the Bulldog Shale of Early Cretaceous age. A gravity survey was undertaken in 1989 to determine the diameter of the impact structure, define the form of the central uplift, and understand the local crustal structure. Data were collected along two orthogonal lines across the structure. In addition to the profiles, a significant number of measurements were made on and around the central uplift. The 1989 gravity data combined with 1963 gravity data and the seismic reflection data provide an excellent data base to interpret the subsurface structure of the Mt. Toondina feature.

  1. Comparative study of the hydrochemical regime in the Gelendzhik and Golubaya Bays, northeastern Black Sea

    Science.gov (United States)

    Kostyleva, A.; Chasovnikov, V.; Chjoo, V.; Menshikova, N.; Kuprikova, N.

    2009-04-01

    The goal of this work was to study the hydrochemical regime in the coastal waters of the northeastern Black Sea. The observations were performed in influenced by significant anthropogenic stress Gelendzhik Bay and at the open coast region (Golubaya Bay). A sampling program has been initiated by the Southern Branch of Shirshov Institute of Oceanology, RAS, (SB SIO RAS) on a weekly basis at the shore line area of «Chernomorets» beach (Gelendzhik Bay) and from the head of pier in the Golubaya Bay. Studies were carried out during a period from January 2001 to December 2008. List of measured parameters includes following: temperature, salinity, dissolved oxygen, biological oxygen demand (BOD), pH, alkalinity, phosphate, organic phosphorus, silicates, nitrates, nitrites, ammonia, urea, organic nitrogen, oil products. The Gelendzhik bay in its different parts is characterized with strong variability of concentrations of hydrochemical parameters. Above all, it relates to complex structure caused by wind impact. Parts of the bay filled with nearshore and sea waters are legibly differ from each other. The bay itself is rather isolated from the open sea, and its liability to man's impact leads to forming of next features of its seasonal variability of physical-chemical state: • On the base of Si/P and Si/N ratios analysis it was shown that the Gelendzhik Bay waters are significantly enriched with nitrogen and phosphorus compounds. • Unlike the Golubaya bay, phosphates are always present in the water of the Gelendzhik Bay and development of photosynthesis is not limited with nutrients. It may lead to processes of intensive eutrophication. • The oxygen saturation in the Gelendzhik Bay periodically descend lower than 80% during the summer period. That means, that even the Bay's surface layer formally corresponds to the hypoxic conditions that testify to the degradation of the ecosystem there. The conclusions obtained during our studies testify that the pollution from

  2. Internal Structure of the Incised Valley Fill in the Hangzhou Bay,Eastern China and Its Geological Implications

    Institute of Scientific and Technical Information of China (English)

    LIN Chunming; LI Guangyue; WANG Baichang; GU Lianxing; ZHUO Hongchun

    2004-01-01

    This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, static sounding and chemical analysis obtained from the present Hangzhou Bay coastal plain. The incised valleys were formed during the last glacial maximum and were subsequently filled with fluvial facies during the post-glacial period. All commercial gases are stored in the flood plain sand lenses of the incised valleys.

  3. Study on the marine sedimentary environment evolution of the southern Laizhou Bay under the impact of port projects

    Science.gov (United States)

    Liu, Xiao; Liu, Jie; Feng, Xiuli

    2016-06-01

    The southern Laizhou Bay is mainly composed of silt-sandy coasts with diverse landforms, and its marine hydrodynamic environment is sensitive to human activities. Marine hydrodynamic and sedimentary environments of the study area have changed under the influence of large-scale port projects in recent years. In this paper, the evolution of hydrodynamic environment, deposition rate, and geochemical characteristics were studied based on sediment grain size, element analysis and 210Pb dating of two cores, in order to analyze the influence of Weifang Port on marine environmental evolution, and provide theoretical and practical basis for protecting marine environment in developing marine resources reasonably. Results showed that sediments of the two cores were relatively coarser and mainly composed of silty sand. Sediments above 230 cm in core WF1 and 218 cm in core WF2 were deposited since 1855 when the Yellow River appeared to deposit its sediments within the modern active delta, and the average deposition rate was between 0.3 and 0.5 cm a-1. Implement of Weifang Port projects in 1997 and 2007 created great influence on the sedimentary environment evolution in the surrounding waters, and the deposition rate was significantly increased. The average annual deposition rates were 5.1 cm and 3.5 cm in WF1 and WF2 respectively between 1997 and 2007. Content of heavy metals in sediments showed no obvious change in the vertical, indicating that the heavy metals were less affected by human activity and there was no significant accumulation of such metals in the study area.

  4. Impact of period and timescale of FDDA analysis nudging on the numerical simulation of tropical cyclones in the Bay of Bengal

    KAUST Repository

    Viswanadhapalli, Yesubabu

    2014-06-22

    In this study, the impact of four-dimensional data assimilation (FDDA) analysis nudging is examined on the prediction of tropical cyclones (TC) in the Bay of Bengal to determine the optimum period and timescale of nudging. Six TCs (SIDR: November 13–16, 2007; NARGIS: April 29–May 02, 2008; NISHA: November 25–28, 2008; AILA: May 23–26, 2009; LAILA: May 18–21, 2010; JAL: November 04–07, 2010) were simulated with a doubly nested Weather Research and Forecasting (WRF) model with a horizontal resolution of 9 km in the inner domain. In the control run for each cyclone, the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analysis and forecasts at 0.5_ resolution are used for initial and boundary conditions. In the FDDA experiments available surface, upper air observations obtained from NCEP Atmospheric Data Project (ADP) data sets were used for assimilation after merging with the first guess through objective analysis procedure. Analysis nudging experiments with different nudging periods (6, 12, 18, and 24 h) indicated a period of 18 or 24 h of nudging during the pre-forecast stage provides maximum impact on simulations in terms of minimum track and intensity forecasts. To determine the optimum timescale of nudging, two cyclone cases (NARGIS: April 28–May 02, 2008; NISHA: November 25–28, 2008) were simulated varying the inverse timescales as 1.0e-4 to 5.0e-4 s−1 in steps of 1.0e-4 s−1. A positive impact of assimilation is found on the simulated characteristics with a nudging coefficient of either 3.0e-4 or 4.0e-4 s−1 which corresponds to a timescale of about 1 h for nudging dynamic (u,v) and thermodynamical (t,q) fields.

  5. Airborne and impact sound transmission in super-light structures

    DEFF Research Database (Denmark)

    Christensen, Jacob Ellehauge; Hertz, Kristian Dahl; Brunskog, Jonas

    2011-01-01

    Super-light structures are newly invented and based on combining lightweight concrete with normal concrete for lighter structures and better structural performance. The overall principle is based on load carrying arches of a normal concrete stabilised and protected from fire by a light......-aggregate concrete. A super-light deck element is developed. It is intended to be lighter than traditional deck structures without compromising the acoustic performance. It is primarily the airborne sound insulation, which is of interest as the requirements for the impact sound insulation to a higher degree can...

  6. Impact of freshwater on a subarctic coastal ecosystem under seasonal sea ice (southeastern Hudson Bay, Canada). III. Feeding success of marine fish larvae

    Science.gov (United States)

    Fortier, L.; Gilbert, M.; Ponton, D.; Ingram, R. G.; Robineau, B.; Legendre, L.

    1996-02-01

    We monitored the feeding success (percent feeding incidence at length and mean feeding ratio at length) of Arctic cod ( Boreogadus saida) and sand lance ( Ammodytes sp.) larvae in relation to prey density, light, temperature and potential predator density under the ice cover of southeastern Hudson Bay in the spring of 1988, 1989 and 1990. Both prey density and light limited larval fish feeding. The relationship between feeding success and actual food availability (nauplii density X irradiance) was adequately described by an Ivlev function which explained 64 and 76% of the variance in Arctic cod and sand lance feeding success respectively. By affecting both prey density and irradiance, the thickness of the Great Whale River plume (as defined by the depth of the 25 isohaline) was the main determinant of prey availability. Arctic cod and sand lance larvae stopped feeding when the depth of the 25 isohaline exceeded 9 m. Limitation of feeding success attributable to freshwater inputs occurred exclusively in 1988, the only time when the depth of the 25 isohaline exceeded the 9 m threshold. The close dependence of larval fish feeding success on the timing of the freshet and plume dynamics suggests a direct link between climate and survival of Arctic cod and sand lance larvae. The actual impact of climate fluctuations and/or hydro-electric developments on recruitment will depend on the fraction of the larval dispersal area of the two species that is affected by river plumes.

  7. The eastern Baffin Bay. A preliminary strategic environmental impact assessment of hydrocarbon activities in the KANUMAS West area; Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Boertmann, D.; Johansen, K.; Maltha Rasmussen, L.; Schiedek, D.; Ugarte, F.; Mosbech, A.; Frederiksen, M.; Bjerrum, M.

    2009-05-15

    The environmental impacts of exploration activities will mainly be disturbance from activities creating noise such as seismic surveys and drilling. The impacts are expected to be relatively small, local and temporary, because of the intermittent nature of the exploration activities. Furthermore, the season for exploration activities is very short and limited to the few months with light ice conditions (June-October). The activities during development, production and transport are on the other hand long-lasting, and there are several activities which have the potential to cause severe environmental impacts. Careful Health, Safety and Environment (HSE) procedures, application of Best Available Technique (BAT) and Best Environmental Practice (BEP), zero-discharge policy and planning in combination with thorough background studies and application of the Precautionary Principle can mitigate most of these. The environmentally most severe accident would be a large oil spill. This has the potential to impact the marine ecosystem on all levels from primary production to the top predators. Oil spill trajectory modelling was carried out by DMI as a part of this SEIA. In most of the modelled oil spill drift scenarios oil does not reach the coasts, but stays offshore. However, three of the 24 scenarios indicate that under certain conditions, oil may reach shores up to several hundred kilometres from the spill site. (ln)

  8. Uncertainty in model predictions of Vibrio vulnificus response to climate variability and change: a Chesapeake Bay case study.

    Directory of Open Access Journals (Sweden)

    Erin A Urquhart

    Full Text Available The effect that climate change and variability will have on waterborne bacteria is a topic of increasing concern for coastal ecosystems, including the Chesapeake Bay. Surface water temperature trends in the Bay indicate a warming pattern of roughly 0.3-0.4°C per decade over the past 30 years. It is unclear what impact future warming will have on pathogens currently found in the Bay, including Vibrio spp. Using historical environmental data, combined with three different statistical models of Vibrio vulnificus probability, we explore the relationship between environmental change and predicted Vibrio vulnificus presence in the upper Chesapeake Bay. We find that the predicted response of V. vulnificus probability to high temperatures in the Bay differs systematically between models of differing structure. As existing publicly available datasets are inadequate to determine which model structure is most appropriate, the impact of climatic change on the probability of V. vulnificus presence in the Chesapeake Bay remains uncertain. This result points to the challenge of characterizing climate sensitivity of ecological systems in which data are sparse and only statistical models of ecological sensitivity exist.

  9. Impact of human activities on subaqueous topographic change in Lingding Bay of the Pearl River estuary, China, during 1955–2013

    Science.gov (United States)

    Wu, Z. Y.; Saito, Yoshiki; Zhao, D. N.; Zhou, J. Q.; Cao, Z. Y.; Li, S. J.; Shang, J. H.; Liang, Y. Y.

    2016-11-01

    Estuaries have been sites of intensive human activities during the past century. Tracing the evolution of subaqueous topography in estuaries on a decadal timescale enables us to understand the effects of human activities on estuaries. Bathymetric data from 1955 to 2010 show that land reclamation decreased the subaqueous area of Lingding Bay, in the Pearl River estuary, by ~170 km2 and decreased its water volume by 615 × 106 m3, representing a net decrease of 11.2 × 106 m3 per year and indicating the deposition of approximately 14.5 Mt/yr of sediment in Lingding Bay during that period. Whereas Lingding Bay was mainly governed by natural processes with slight net deposition before 1980, subsequent dredging and large port engineering projects changed the subaqueous topography of the bay by shallowing its shoals and deepening its troughs. Between 2012 and 2013, continuous dredging and a surge of sand excavation resulted in local changes in water depth of ± 5 m/yr, far exceeding the magnitude of natural topographic evolution in Lingding Bay. Reclamation, dredging, and navigation-channel projects removed 8.4 Mt/yr of sediment from Lingding Bay, representing 29% of the sediment input to the bay, and these activities have increased recently.

  10. Post-impact sedimentation in the Ritland impact structure, Southwestern Norway

    OpenAIRE

    Tomczyk, Michal

    2010-01-01

    A succession of crater infill sediments is preserved within the Ritland impact structure. Ritland is good example of a small depositional basin where a range of processes from debris flows to turbiditic currents and finally suspension fall-out took place within a very restricted area. Immediately after impact slumps/slides, and mass flows dominated, later to be replaced by running water activities in much calmer basin environment, like fine-grained sedimentation. The sedimentary successions o...

  11. Sound structure and input frequency impact on noun plural acquisition

    DEFF Research Database (Denmark)

    Kjærbæk, Laila; Christensen, René dePont; Basbøll, Hans

    2014-01-01

    This study analyses the emergence of the noun plural category in typically developing Danish-speaking children from its first appearance up to the age of 10 years, focusing on the impact of sound structure and input frequency. We use a multi-method research approach comparing different data types...

  12. Reproduction and structure of the population of the Chaetognath Parasagitta friderici in Guanabara Bay (Brazil) based on short term sampling.

    Science.gov (United States)

    Mendes, Fabiana; Figueiredo, Gisela M de; Valentin, Jean L

    2012-03-01

    The aim of this study was to describe the total density, densities of developmental stages and the reproduction period of Parasagitta friderici. Weekly samples were collected at one station in the channel of Guanabara Bay, Rio de Janeiro, during one year. Three vertical hauls were made for each sample, and P. friderici was separated, the developmental stages were identified, and body length (BL), ovary length (OL) and seminal vesicle width (SVW) were measured. Throughout the year P. friderici was the most abundant chaetognath species occurring in all four developmental stages, the densities of which varied from week to week. Higher densities of adults occurred in the spring, followed by peaks of juveniles in the summer. Although P. friderici seems to reproduce continuously in Guanabara Bay, a reproductive peak was apparent during the spring. The intensification of reproduction during the spring, with juveniles occurring in the summer, seems to be related to the period of higher food supply during the rainy season and intrusions of the South Atlantic Central Water.

  13. Guard Ring Width Impact on Impact Parameter Performances and Structure Simulations

    CERN Document Server

    Gouldwell, A; Rahman, M; Bates, R; Wemyss, M; Murphy, G; Turner, P; Biagi, S F

    2003-01-01

    The 1 mm guard ring structure of the VELO sensors has been simulated. The performance of the baseline design is considered and a design which improves the electric field characteristics proposed. Designs which would permit a reduced guard ring width, to 0.5 mm or better, are also discussed and shown to also have similarly good electric field performances. The effect of implementing these designs on the impact parameter resolution of LHCb is found to be better than 5 %. This design is currently being fabricated. Finally, a very different structure, the trench guard ring, is considered which would then allow an impact parameter resolution improvement of approximately 7 %.

  14. Structure and Dynamics of Coauthorship, Citation, and Impact within CSCW

    CERN Document Server

    Keegan, Brian; Finholt, Thomas A; Kaye, Joseph "Jofish"

    2013-01-01

    CSCW has stabilized as an interdisciplinary venue for computer, information, cognitive, and social scientists but has also undergone significant changes in its format in recent years. This paper uses methods from social network analysis and bibliometrics to re-examine the structures of CSCW a decade after its last systematic analysis. Using data from the ACM Digital Library, we analyze changes in structures of coauthorship and citation between 1986 and 2013. Statistical models reveal significant but distinct patterns between papers and authors in how brokerage and closure in these networks affects impact as measured by citations and downloads. Specifically, impact is unduly influenced by structural position, such that ideas introduced by those in the core of the CSCW community (e.g., elite researchers) are advantaged over those introduced by peripheral participants (e.g., newcomers). This finding is examined in the context of recent changes to the CSCW conference that may have the effect of upsetting the pref...

  15. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  16. Team Structure and Scientific Impact of "Big Science" Research

    DEFF Research Database (Denmark)

    Lauto, Giancarlo; Valentin, Finn; Jeppesen, Jacob

    This paper summarizes preliminary results from a project studying how the organizational and cognitive features of research carried out in a Large Scale Research Facility (LSRF) affect scientific impact. The study is based on exhaustive bibliometric mapping of the scientific publications of the N......This paper summarizes preliminary results from a project studying how the organizational and cognitive features of research carried out in a Large Scale Research Facility (LSRF) affect scientific impact. The study is based on exhaustive bibliometric mapping of the scientific publications...... and for their skill structures are discussed....

  17. Macrozooplankton predation impact on anchovy (Engraulis encrasicolus) eggs mortality at the Bay of Biscay shelf break spawning centre

    KAUST Repository

    Albaina, Aitor

    2014-11-23

    A real-time PCR based method involving a species-specific probe was applied to detect Engraulis encrasicolus eggs predation by the macrozooplankton community during the 2011 spawning season. Three locations along the shelf break presenting contrasting but high prey densities were sampled. A total of 840 individuals from 38 taxa of potential macrozooplankton predators were assayed for E. encrasicolus DNA presence and 27 presented at least one positive signal. Carnivorous copepods were responsible for the most predation events (66%) followed by euphausiids (16%), chaetognaths (5%), and myctophid fish (4%). Macrozooplankton predation on anchovy eggs followed a type-I functional response with daily mortalities <4% of available prey abundance suggesting a negligible impact on the species recruitment at the shelf break spawning centre. © 2014 International Council for the Exploration of the Sea 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Impact of the Ownership Structure on Corporate Management in Engineering

    Directory of Open Access Journals (Sweden)

    Dieieva Nataliia E.

    2014-02-01

    Full Text Available The article analyses impact of the ownership structure on corporate management in the engineering industry of Ukraine. In order to detect impact of the structure of corporate ownership on corporate management the article uses general scientific and special methods of study: method of critical analysis and generalisation of theoretical studies, comparison method and statistical method. Analysis of engineering enterprises confirmed availability of impact of the structure of corporate ownership on corporate management. The article also shows that the engineering industry of Ukraine is characterised with the concentrated ownership structure, which has the following features: restriction of rights of minority shareholders with respect to management and control in a joint stock company; availability of corporate conflicts between majority and minority shareholders; availability of intense control of owners over management, which influences efficiency of making managerial decisions; hired managers and enterprise employees have no possibility to acquire stock of a joint stock company including in the form of bonuses and incentives; the controlling owner is interested in efficient activity of the enterprise and tries to create necessary conditions for this. The conducted studies give a possibility to establish that a share of stock that belongs to a hired executive body is smaller in those joint stock companies in which concentration of ownership is higher. The article also shows that the higher ownership concentration the higher is the probability that the owner would be a part of controlling bodies.

  19. Impact of freshwater on a subarctic coastal ecosystem under seasonal sea ice (southeastern Hudson Bay, Canada) II. Production and export of microalgae

    Science.gov (United States)

    Legendre, L.; Robineau, B.; Gosselin, M.; Michel, C.; Ingram, R. G.; Fortier, L.; Therriault, J. C.; Demers, S.; Monti, D.

    1996-02-01

    In the under-ice plume of the Grande rivière de la Baleine (Great Whale River) and offshore waters of southeastern Hudson Bay (Canada), several environmental factors influence the distribution, growth, taxonomic composition and sedimentation of algae found in the sea ice, at the ice-water interface and in the underlying water column. During the spring and early summer, these factors include: salinity of bottom ice, water turbidity, nutrients and vertical stability of the water column. In the present study, relationships between three predictor variables (water salinity, river runoff and seasonal air temperature index) and biological variables are used to assess the impact of freshwater on production and export of microalgae. Relationships are derived from existing data, which were collected between 1978 and 1990. Correlations with water salinity are positive for some variables (salinity of bottom ice, phosphate, ammonium, Σ:Si, and algae in bottom ice and at the interface) and negative for others (coefficient of light attenuation, silicate, ΣN:P, ΣSi:P and water column phytoplankton). Using together salinity and the seasonal index leads to improved proportions of explained variance for nitrate, ammonium, ΣN:P and phytoplankton. The amount of sedimenting algae is positively correlated with runoff, and chemical composition (C/N) of the sedimenting material is negatively correlated with salinity. The empirical relationships are applied to the results of a model of river plume dynamics, for three runoff conditions. Seasonally averaged total Chl. a concentrations, derived from the model, are higher for maximum river runoff than for mean or minimum conditions. This is because, in the studied environment, areal concentrations of phytoplankton are higher than those of ice algae, especially under condition of maximum runoff.

  20. Bayes and empirical Bayes: do they merge?

    CERN Document Server

    Petrone, Sonia; Scricciolo, Catia

    2012-01-01

    Bayesian inference is attractive for its coherence and good frequentist properties. However, it is a common experience that eliciting a honest prior may be difficult and, in practice, people often take an {\\em empirical Bayes} approach, plugging empirical estimates of the prior hyperparameters into the posterior distribution. Even if not rigorously justified, the underlying idea is that, when the sample size is large, empirical Bayes leads to "similar" inferential answers. Yet, precise mathematical results seem to be missing. In this work, we give a more rigorous justification in terms of merging of Bayes and empirical Bayes posterior distributions. We consider two notions of merging: Bayesian weak merging and frequentist merging in total variation. Since weak merging is related to consistency, we provide sufficient conditions for consistency of empirical Bayes posteriors. Also, we show that, under regularity conditions, the empirical Bayes procedure asymptotically selects the value of the hyperparameter for ...

  1. Impact origin of the Sudbury structure: Evolution of a theory

    Science.gov (United States)

    Lowman, Paul D., Jr.

    1992-01-01

    This paper reviews the origin, development, and present status of the widely accepted theory, proposed by Robert S. Dietz in 1962, that the Sudbury structure was formed by meteoritic or asteroidal impact. The impact theory for the origin of the Sudbury structure seems supported by a nearly conclusive body of evidence. However, even assuming an impact origin to be correct, at least three major questions require further study: (1) the original size and shape of the crater, before tectonic deformation and erosion; (2) the source of the melt now forming the Sudbury Igneous Complex; and (3) the degree, if any, to which the Ni-Cu-platinum group elements are meteoritic. The history of the impact theory illustrates several under-appreciated aspects of scientific research: (1) the importance of cross-fertilization between space research and terrestrial geology; (2) the role of the outsider in stimulating thinking by insiders; (3) the value of small science, at least in the initial stages of an investigation, Dietz's first field work having been at his own expense; and (4) the value of analogies (here, between the Sudbury Igneous Complex and the maria), which although incorrect in major aspects, may trigger research on totally new lines. Finally, the Sudbury story illustrates the totally unpredictable and, by implication, unplannable nature of basic research, in that insight to the origin of the world's then-greatest Ni deposit came from the study of tektites and the Moon.

  2. Bayes linear statistics, theory & methods

    CERN Document Server

    Goldstein, Michael

    2007-01-01

    Bayesian methods combine information available from data with any prior information available from expert knowledge. The Bayes linear approach follows this path, offering a quantitative structure for expressing beliefs, and systematic methods for adjusting these beliefs, given observational data. The methodology differs from the full Bayesian methodology in that it establishes simpler approaches to belief specification and analysis based around expectation judgements. Bayes Linear Statistics presents an authoritative account of this approach, explaining the foundations, theory, methodology, and practicalities of this important field. The text provides a thorough coverage of Bayes linear analysis, from the development of the basic language to the collection of algebraic results needed for efficient implementation, with detailed practical examples. The book covers:The importance of partial prior specifications for complex problems where it is difficult to supply a meaningful full prior probability specification...

  3. Circulation and haline structure of a microtidal bay in the Sea of Japan influenced by the winter monsoon and the Tsushima Warm Current

    Science.gov (United States)

    Itoh, Sachihiko; Kasai, Akihide; Takeshige, Aigo; Zenimoto, Kei; Kimura, Shingo; Suzuki, Keita W.; Miyake, Yoichi; Funahashi, Tatsuhiro; Yamashita, Yoh; Watanabe, Yoshiro

    2016-08-01

    Mooring and hydrographic surveys were conducted in Tango Bay, a microtidal region of freshwater influence (ROFI) in the Sea of Japan, in order to clarify the circulation pattern in the bay and its driving forces. Monthly mean velocity records at four stations revealed an inflow and outflow at the eastern and northern openings of the bay, respectively, indicating an anticyclonic circulation across the bay mouth. The circulation was significantly intensified in winter, in accordance with the prevailing NW wind component of the winter monsoon. The anticyclonic circulation at the bay mouth was connected to an estuarine circulation that was evident near the mouth of the Yura River at the bay head. Surface salinity just offshore of the river mouth was closely related to the Yura River discharge, whereas in lower layers the offshore water had a stronger influence on salinity. Prior to a seasonal increase in the Yura River discharge, summer salinity decreased markedly through the water column in Tango Bay, possibly reflecting intrusion of the Changjiang Diluted Water transported by the Tsushima Warm Current. In contrast with the traditional assumption that estuarine circulation is controlled mainly by river discharge and tidal forcing, the circulation in Tango Bay is strongly influenced by seasonal wind and the Tsushima Warm Current. The narrow shelf may be responsible for the strong influence of the Tsushima Warm Current on circulation and water exchange processes in Tango Bay.

  4. Grid faults' impact on wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca D.; Cutululis, A. Nicolaos; Iov, Florin;

    2007-01-01

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight...... on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aerolastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation...... of the wind turbine during grid faults. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  5. Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures

    Science.gov (United States)

    French, Bevan M.

    1998-01-01

    This handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures emphasizes terrestrial impact structures, field geology, and particularly the recognition and petrographic study of shock-metamorphic effects in terrestrial rocks. Individual chapters include: 1) Landscapes with Craters: Meteorite Impacts, Earth, and the Solar System; 2) Target Earth: Present, Past and Future; 3) Formation of Impact Craters; 4) Shock-Metamorphic Effects in Rocks and Minerals; 5) Shock-Metamorphosed Rocks (Impactities) in Impact Structures; 6) Impact Melts; 7) How to Find Impact Structures; and 8) What Next? Current Problems and Future Investigations.

  6. Impact of active controls technology on structural integrity

    Science.gov (United States)

    Noll, Thomas; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry

    1991-01-01

    This paper summarizes the findings of The Technical Cooperation Program to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting the loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle. The potential for active controls to adversely affect structural integrity is described, and load predictions obtained using two state-of-the-art analytical methods are given.

  7. Noise Impact on European Sea Bass Behavior: Temporal Structure Matters.

    Science.gov (United States)

    Neo, Yik Yaw; Seitz, Johanna; Kastelein, Ronald A; Winter, Hendrik V; Cate, Carel Ten; Slabbekoorn, Hans

    2016-01-01

    Anthropogenic sounds come in different forms, varying not only in amplitude and frequency spectrum but also in temporal structure. Although fish are sensitive to the temporal characteristics of sound, little is known about how their behavior is affected by anthropogenic sounds of different temporal patterns. We investigated this question using groups of Dicentrarchus labrax (European sea bass) in an outdoor basin. Our data revealed that the temporal pattern of sound exposure is important in noise impact assessments.

  8. Assessing the Impacts of Chinese Sustainable Ground Transportation on the Dynamics of Urban Growth: A Case Study of the Hangzhou Bay Bridge

    Directory of Open Access Journals (Sweden)

    Qing Zheng

    2016-07-01

    Full Text Available Although China has promoted the construction of Chinese Sustainable Ground Transportation (CSGT to guide sustainable development, it may create substantial challenges, such as rapid urban growth and land limitations. This research assessed the effects of the Hangzhou Bay Bridge on impervious surface growth in Cixi County, Ningbo, Zhejiang Province, China. Changes in impervious surfaces were mapped based on Landsat images from 1995, 2002, and 2009 using a combination of multiple endmember spectral mixture analysis (MESMA and landscape metrics. The results indicated that the area and density of impervious surfaces increased significantly during construction of the Hangzhou Bay Bridge (2002–2009. Additionally, the bridge and connected road networks promoted urban development along major roads, resulting in compact growth patterns of impervious surfaces in urbanized regions. Moreover, the Hangzhou Bay Bridge promoted the expansion and densification of impervious surfaces in Hangzhou Bay District, which surrounds the bridge. The bridge also accelerated socioeconomic growth in the area, promoting rapid urban growth in Cixi County between 2002 and 2009. Overall, the Hangzhou Bay Bridge is an important driver of urban growth in Cixi County, and policy suggestions for sustainable urban growth should be adopted in the future.

  9. Reproduction and structure of the population of the Chaetognath Parasagitta friderici in Guanabara Bay (Brazil based on short term sampling

    Directory of Open Access Journals (Sweden)

    Fabiana Mendes

    2012-03-01

    Full Text Available The aim of this study was to describe the total density, densities of developmental stages and the reproduction period of Parasagitta friderici. Weekly samples were collected at one station in the channel of Guanabara Bay, Rio de Janeiro, during one year. Three vertical hauls were made for each sample, and P. friderici was separated, the developmental stages were identified, and body length (BL, ovary length (OL and seminal vesicle width (SVW were measured. Throughout the year P. friderici was the most abundant chaetognath species occurring in all four developmental stages, the densities of which varied from week to week. Higher densities of adults occurred in the spring, followed by peaks of juveniles in the summer. Although P. friderici seems to reproduce continuously in Guanabara Bay, a reproductive peak was apparent during the spring. The intensification of reproduction during the spring, with juveniles occurring in the summer, seems to be related to the period of higher food supply during the rainy season and intrusions of the South Atlantic Central Water.O objetivo deste estudo foi descrever a densidade total, densidades dos estágios de desenvolvimento e o período reprodutivo de Parasagitta friderici. As coletas foram realizadas semanalmente durante um ano em uma estação no canal da Baía de Guanabara, Rio de Janeiro. Foram realizados três arrastos verticais em cada amostragem e, P. friderici foi separada, os estágios de desenvolvimento identificados e o comprimento do corpo, comprimento dos ovários e a largura da vesícula seminal foram medidos. Ao longo do ano, P. friderici foi a espécie de Chaetognatha mais abundante, ocorrendo em todos os quatro estágios de desenvolvimento, dos quais as densidades variaram entre as semanas. As densidades mais altas de adultos ocorreram na primavera seguidas de picos de juvenis no verão. Embora, P. friderici se reproduza continuamente na baía de Guanabara, um pico reprodutivo foi aparente

  10. A Glance at Bohai Bay Oil Province

    Institute of Scientific and Technical Information of China (English)

    Gao Shoubai

    1995-01-01

    @@ Chinese oil industry keeps on developing in 1994. The oil production of Bohai Bay Oil Province located in East China also keeps on growing. Geologically,the total area of Bohai Bay Basin is about 200 000 km2 and the main structural units are: Liaohe Depression, Huanghua Depression,Jizhong Depression, Linqing Depression, Jiyang Depression, Changwei Depression, Bozhong Depression,Chengning Uplift and Cangjing Uplift (see figure 1). Area of the main structural units is listed in following:

  11. Ten-year variations in population structure of pink-shrimp in a southwestern Atlantic Bay affected by highway construction

    Directory of Open Access Journals (Sweden)

    Felipe Freitas Jr

    2011-12-01

    Full Text Available OBJECTIVES: Population structures of Farfantepenaeus brasiliensis and F. paulensis, consisting mainly of juveniles, were evaluated during the construction of an expressway along a mangrove area. Estuarine regions in southern Brazil function as sites for reproduction, nursery and growth of a variety of organisms, including two of the most important species of shrimp for fisheries in the southwestern Atlantic. Shrimps were collected in Saco dos Limões creek, Baía-Sul, Florianópolis, State of Santa Catarina, four times a year, by day and night, between 1997 and 2006. Fluctuations in the abundances of shrimp appear to be related to their life cycles, with largest abundances in Summer and Spring, rather than to impacts promoted by dredging activities during the expressway construction.OBJETIVOS: A estrutura populacional de Farfantepenaeus brasiliensis e F. paulensis, consistindo principalmente de juvenis, foi avaliada durante a construção de uma via expressa ao longo de uma área de manguezais. Regiões estuarinas do sul do Brasil funcionam como locais de reprodução, berçários e de crescimento de uma variedade de organismos, incluindo duas das mais importantes espécies de camarões comerciais do Atlântico Sul Ocidental. Camarões foram coletados no Saco dos Limões, Baía Sul, Florianópolis, Estado de Santa Catarina, trimestralmente, de dia e de noite, entre 1997 e 2006. Flutuações em abundâncias de camarões podem estar relacionados aos seus ciclos de vida, com as maiores abundâncias no verão e primavera, ao invés de impactos promovidos pelas atividades de dragagem durante a construção da via expressa.

  12. A full Bayes before-after study accounting for temporal and spatial effects: Evaluating the safety impact of new signal installations.

    Science.gov (United States)

    Sacchi, Emanuele; Sayed, Tarek; El-Basyouny, Karim

    2016-09-01

    Recently, important advances in road safety statistics have been brought about by methods able to address issues other than the choice of the best error structure for modeling crash data. In particular, accounting for spatial and temporal interdependence, i.e., the notion that the collision occurrence of a site or unit times depend on those of others, has become an important issue that needs further research. Overall, autoregressive models can be used for this purpose as they can specify that the output variable depends on its own previous values and on a stochastic term. Spatial effects have been investigated and applied mostly in the context of developing safety performance functions (SPFs) to relate crash occurrence to highway characteristics. Hence, there is a need for studies that attempt to estimate the effectiveness of safety countermeasures by including the spatial interdependence of road sites within the context of an observational before-after (BA) study. Moreover, the combination of temporal dynamics and spatial effects on crash frequency has not been explored in depth for SPF development. Therefore, the main goal of this research was to carry out a BA study accounting for spatial effects and temporal dynamics in evaluating the effectiveness of a road safety treatment. The countermeasure analyzed was the installation of traffic signals at unsignalized urban/suburban intersections in British Columbia (Canada). The full Bayes approach was selected as the statistical framework to develop the models. The results demonstrated that zone variation was a major component of total crash variability and that spatial effects were alleviated by clustering intersections together. Finally, the methodology used also allowed estimation of the treatment's effectiveness in the form of crash modification factors and functions with time trends.

  13. Study on Headland-Bay Sandy Coast Stability in South China Coasts

    Institute of Scientific and Technical Information of China (English)

    YU Ji-tao; CHEN Zi-shen

    2011-01-01

    Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization,extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection.However,little concern focuses on this in China.The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches.This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China.The empirical bay equation can morphologically estimate beach stabilization state,but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades.By using Digital Shoreline Analysis System suggested by USGS,the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000.The conclusions of this paper include that(a)most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000;(b)two bays,Haimen Bay and Hailingshan Bay,originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation,have been unstable by the influence of coastal engineering;and(c)these 31 bays have different recession and accretion characters occurring in some bays and some segments.On the one hand,some bays totally exhibit accretion,but some bays show erosion on the whole.Shanwei Bay,Houmen Bay,Pinghai Bay and Yazhou Bay have the similar planfotms,characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments.On the other hand,different segments of some bays have two dissimilar

  14. Geochemical Comparison of Four Cores from the Manson Impact Structure

    Science.gov (United States)

    Korotev, Randy L.; Rockow, Kaylynn M.; Jolliff, Bradley L.; Haskin, Larry A.; McCarville, Peter; Crossey, Laura J.

    1996-01-01

    Concentrations of 33 elements were determined in relatively unaltered, matrix-rich samples of impact breccia at approximately 3-m-depth intervals in the M-1 core from the Manson impact structure, Iowa. In addition, 46 matrix-rich samples from visibly altered regions of the M-7, M-8, and M-10 cores were studied, along with 42 small clasts from all four cores. Major element compositions were determined for a subset of impact breccias from the M-1 core, including matrix-rich impact-melt breccia. Major- and trace-element compositions were also determined for a suite of likely target rocks. In the M-1 core, different breccia units identified from lithologic examination of cores are compositionally distinct. There is a sharp compositional discontinuity at the boundary between the Keweenawan-shale-clast breccia and the underlying unit of impact-melt breccia (IMB) for most elements, suggesting minimal physical mixing between the two units during emplacement. Samples from the 40-m-thick IMB (M-1) are all similar to each other in composition, although there are slight increases in concentration with depth for those elements that have high concentrations in the underlying fragmental-matrix suevite breccia (SB) (e.g., Na, Ca, Fe, Sc), presumably as a result of greater clast proportions at the bottom margin of the unit of impact-melt breccia. The high degree of compositional similarity we observe in the impact-melt breccias supports the interpretation that the matrix of this unit represents impact melt. That our analyses show such compositional similarity results in part from our technique for sampling these breccias: for each sample we analyzed a few small fragments (total mass: approximately 200 mg) selected to be relatively free of large clasts and visible signs of alteration instead of subsamples of powders prepared from a large mass of breccia. The mean composition of the matrix-rich part of impact-melt breccia from the M-1 core can be modeled as a mixture of approximately

  15. Computational modeling and impact analysis of textile composite structures

    Science.gov (United States)

    Hur, Hae-Kyu

    This study is devoted to the development of an integrated numerical modeling enabling one to investigate the static and the dynamic behaviors and failures of 2-D textile composite as well as 3-D orthogonal woven composite structures weakened by cracks and subjected to static-, impact- and ballistic-type loads. As more complicated modeling about textile composite structures is introduced, some of homogenization schemes, geometrical modeling and crack propagations become more difficult problems to solve. To overcome these problems, this study presents effective mesh-generation schemes, homogenization modeling based on a repeating unit cell and sinusoidal functions, and also a cohesive element to study micro-crack shapes. This proposed research has two: (1) studying behavior of textile composites under static loads, (2) studying dynamic responses of these textile composite structures subjected to the transient/ballistic loading. In the first part, efficient homogenization schemes are suggested to show the influence of textile architectures on mechanical characteristics considering the micro modeling of repeating unit cell. Furthermore, the structures of multi-layered or multi-phase composites combined with different laminar such as a sub-laminate, are considered to find the mechanical characteristics. A simple progressive failure mechanism for the textile composites is also presented. In the second part, this study focuses on three main phenomena to solve the dynamic problems: micro-crack shapes, textile architectures and textile effective moduli. To obtain a good solutions of the dynamic problems, this research attempts to use four approaches: (I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, (II) development of an efficient computational approach enabling one to perform transient

  16. Influence of near-shore marine structures in a beach nourishment project on tidal currents in Haitan Bay, facing the Taiwan Strait

    Institute of Scientific and Technical Information of China (English)

    顾杰; 马悦; 王彬谕; Jueyi SUI; 匡翠萍; 刘建辉; 雷刚

    2016-01-01

    The Longfengtou Beach in the Haitan Bay, located in Fujian Province of China and facing the Haitan Strait, has been suffering severe erosion due to the construction of seawalls. A simple beach nourishment project implemented has not achieved the anticipated beach restoration. Thus a practical solution has to rely on a combination with near-shore marine structures. In this study, a 2-D calibrated flow model is set up to investigate the effects of three different layouts of near-shore marine structures on the tidal current. It is shown that the breakwaters situated in both the north and south ends play a vital part in the protection against erosion. The offshore breakwaters can serve as a barrier to obstruct the current circulation then reduce the current velocity. The groyne linking the Guimo islet and the coast significantly reduces the south-to-north water exchange through the channel and redirects the current direction nearly perpendicular to the north breakwater, which cuts off the longshore transport that may have a negative influence on the beach, especially, the northern part. It is also noted that the monsoon at the site with different directions increases the current velocity. In general, proper layouts of marine structures can reduce the current velocity thus lead to less intense sand transport near the beach.

  17. Structure and function of soil microbial community in artificially planted Sonneratia apetala and S. caseolaris forests at different stand ages in Shenzhen Bay, China.

    Science.gov (United States)

    Yang, Q; Lei, A P; Li, F L; Liu, L N; Zan, Q J; Shin, P K S; Cheung, S G; Tam, N F Y

    2014-08-30

    The present study examined the relationships between soil characteristics, microbial community structure and function in the forests artificially planted with exotic Sonneratia apetala at stand ages of 1-, 2-, 7-, 10- and 14-years and Sonneratia caseolaris of 1-, 4-, 7-, 10- and 14-years in Futian National Nature Reserve, Shenzhen Bay, China. The 7-years old forests of both Sonneratia species reached peak growth and had the highest content of nitrogen and phosphorus, enzymatic activities, including dehydrogenase, cellulase, phosphatase, urease and ß-glucosidase, except arylsulphatase which increased continuously with stand ages. The microbial community structure reflected by phospholipid fatty acid (PLFA) profiles also reached the maximum value in the 7-years old forests and soil bacterial PLFAs in both forests were significantly higher than fungal PLFAs. The canonical correlation analysis revealed that differences in microbial structural variables were significantly correlated to the differences in their functional variables, and the highest correlation was found between the soil enzymatic activities and the content of carbon and nitrogen.

  18. Heterotrophic bacteria of the Dapeng Bay in the South China Sea: community structure, abundance, and the relationships of culturablity with environmental factors

    Institute of Scientific and Technical Information of China (English)

    JIANG Fajun; HU Zhangli; HU Chaoqun

    2010-01-01

    The community composition,abundance and culturablity of heterotrophic bacterioplankton in the Dapeng Bay of the South China Sea were investigated by morphological method,bacterial cultivation and biochemical methods over an annual cycle.Aeromonas and Pseudomonas were the predominant genera among the Gram-negative bacteria.The bacterioplankton abundance fluctuated from 2.07×10s to 2.44×109 cells/dm3,and culturable bacteria abundance ranged between0.1×106 and 16.07×106 CFU/dm3.The Culturablity of heterotrophic bacteria ranged between0.01% and 1.31%.The relationship between bacterial culturablity and the environmental factors was also studied in different sites of the Dapeng Bay.Throughout the bay,a significantly positive relationship was evidenced between bacterial culturability and temperature,meanswhile bacterial culturability was significantly inversely related with salinity.The positive relationship was shown at the central bay while a negative relationship was observed at the bay mouth and there was no significant correlation at top bay between bacterial culturablity and chlorophyll a of sea water.A positive relationship was found between culturability and DIN all the bay,but DIP showed a significantly negative relationship with bacterial culturability only at the mouth of the bay.

  19. Hydrocode modeling of the Sierra Madera impact structure

    Science.gov (United States)

    Goldin, Tamara J.; Wünnemann, Kai; Melosh, H. Jay; Collins, Gareth S.

    We present the first hydrocode simulations of the formation of the Sierra Madera structure (west Texas, USA), which was caused by an impact into a thick sedimentary target sequence. We modeled Sierra Madera using the iSALE hydrocode, and here we present two best-fit models: 1) a crater with a rim (final crater) diameter of ˜12 km, in agreement with previous authors' interpretations of the original structure, and 2) a crater ˜16 km in diameter with increased postimpact erosion. Both models fit some of the geologic observational data, but discrepancies with estimates of peak shock pressure, extent of deformation, and stratigraphic displacement remain. This study suggests that Sierra Madera may be a larger crater than previously reported and illustrates some of the challenges in simulating impact deformation of sedimentary lithologies. As many terrestrial craters possess some amount of sedimentary rocks in the target sequence, numerical models of impacts into sedimentary targets are essential to our understanding of target rock deformation and the mechanics of crater formation.

  20. Seasonal variability in free-living marine nematode community structure in a sandy beach of the Taiping Bay of Qingdao, China

    Institute of Scientific and Technical Information of China (English)

    LIU Haibin; ZHANG Zhinan; FAN Shiliang; HUA Er; DENG Ke

    2008-01-01

    Nematode assemblage composition,trophic structure and biodiversity were followed over an annual cycle in a sandy beach of the Taiping Bay of Qingdao,China.Nematode assemblage in the sandy beach maintained a high genus diversity (75 genera).Micro-laimus and Bathylaimus were the dominant genus of the nematode assemblage,accounting for 66% of the total nematode abun-dance.The nematodes' dominant trophic structure changed seasonally as a response to the seasonal changes in food quality.Epi-growth-feeder nematodes (2A) were the dominant trophic groups in the trophic structure with the highest abundance in spring be-cause of phytoplankton bloom,while the feeding type (1B) showed higher abundance in summer that was due to the increasing of sediment detritus after spring bloom.Furthermore,species diversity and evenness calculated on nematodes identified to the genus level displayed significant temporal changes,which was also reflected by the index of trophic diversity.According to the cluster analysis,the nematode community structure of the whole year was clearly separated into two periods ( A and B).Biota-Environ-ment matching (BIOENV) results showed that seawater temperature,sediment Chl a and grain size were responsible for the nema-tode community structure variation in spring and summer period (Period A).However,seawater/interstitial water temperature,interstitial water dissolved oxygen concentration,interstitial water salinity,and sediment Ph a a were more important in construc-ting the autumn and winter period ( Period B) nematode community structure.

  1. Impact of constrained rewiring on network structure and node dynamics.

    Science.gov (United States)

    Rattana, P; Berthouze, L; Kiss, I Z

    2014-11-01

    In this paper, we study an adaptive spatial network. We consider a susceptible-infected-susceptible (SIS) epidemic on the network, with a link or contact rewiring process constrained by spatial proximity. In particular, we assume that susceptible nodes break links with infected nodes independently of distance and reconnect at random to susceptible nodes available within a given radius. By systematically manipulating this radius we investigate the impact of rewiring on the structure of the network and characteristics of the epidemic. We adopt a step-by-step approach whereby we first study the impact of rewiring on the network structure in the absence of an epidemic, then with nodes assigned a disease status but without disease dynamics, and finally running network and epidemic dynamics simultaneously. In the case of no labeling and no epidemic dynamics, we provide both analytic and semianalytic formulas for the value of clustering achieved in the network. Our results also show that the rewiring radius and the network's initial structure have a pronounced effect on the endemic equilibrium, with increasingly large rewiring radiuses yielding smaller disease prevalence.

  2. Impacts of Watershed Characteristics and Crop Rotations on Winter Cover Crop Nitrate-Nitrogen Uptake Capacity within Agricultural Watersheds in the Chesapeake Bay Region.

    Science.gov (United States)

    Lee, Sangchul; Yeo, In-Young; Sadeghi, Ali M; McCarty, Gregory W; Hively, W Dean; Lang, Megan W

    2016-01-01

    The adoption rate of winter cover crops (WCCs) as an effective conservation management practice to help reduce agricultural nutrient loads in the Chesapeake Bay (CB) is increasing. However, the WCC potential for water quality improvement has not been fully realized at the watershed scale. This study was conducted to evaluate the long-term impact of WCCs on hydrology and NO3-N loads in two adjacent watersheds and to identify key management factors that affect the effectiveness of WCCs using the Soil and Water Assessment Tool (SWAT) and statistical methods. Simulation results indicated that WCCs are effective for reducing NO3-N loads and their performance varied based on planting date, species, soil characteristics, and crop rotations. Early-planted WCCs outperformed late-planted WCCs on the reduction of NO3-N loads and early-planted rye (RE) reduced NO3-N loads by ~49.3% compared to the baseline (no WCC). The WCCs were more effective in a watershed dominated by well-drained soils with increased reductions in NO3-N fluxes of ~2.5 kg N·ha-1 delivered to streams and ~10.1 kg N·ha-1 leached into groundwater compared to poorly-drained soils. Well-drained agricultural lands had higher transport of NO3-N in the soil profile and groundwater due to increased N leaching. Poorly-drained agricultural lands had lower NO3-N due to extensive drainage ditches and anaerobic soil conditions promoting denitrification. The performance of WCCs varied by crop rotations (i.e., continuous corn and corn-soybean), with increased N uptake following soybean crops due to the increased soil mineral N availability by mineralization of soybean residue compared to corn residue. The WCCs can reduce N leaching where baseline NO3-N loads are high in well-drained soils and/or when residual and mineralized N availability is high due to the cropping practices. The findings suggested that WCC implementation plans should be established in watersheds according to local edaphic and agronomic

  3. Impacts of Watershed Characteristics and Crop Rotations on Winter Cover Crop Nitrate-Nitrogen Uptake Capacity within Agricultural Watersheds in the Chesapeake Bay Region.

    Directory of Open Access Journals (Sweden)

    Sangchul Lee

    Full Text Available The adoption rate of winter cover crops (WCCs as an effective conservation management practice to help reduce agricultural nutrient loads in the Chesapeake Bay (CB is increasing. However, the WCC potential for water quality improvement has not been fully realized at the watershed scale. This study was conducted to evaluate the long-term impact of WCCs on hydrology and NO3-N loads in two adjacent watersheds and to identify key management factors that affect the effectiveness of WCCs using the Soil and Water Assessment Tool (SWAT and statistical methods. Simulation results indicated that WCCs are effective for reducing NO3-N loads and their performance varied based on planting date, species, soil characteristics, and crop rotations. Early-planted WCCs outperformed late-planted WCCs on the reduction of NO3-N loads and early-planted rye (RE reduced NO3-N loads by ~49.3% compared to the baseline (no WCC. The WCCs were more effective in a watershed dominated by well-drained soils with increased reductions in NO3-N fluxes of ~2.5 kg N·ha-1 delivered to streams and ~10.1 kg N·ha-1 leached into groundwater compared to poorly-drained soils. Well-drained agricultural lands had higher transport of NO3-N in the soil profile and groundwater due to increased N leaching. Poorly-drained agricultural lands had lower NO3-N due to extensive drainage ditches and anaerobic soil conditions promoting denitrification. The performance of WCCs varied by crop rotations (i.e., continuous corn and corn-soybean, with increased N uptake following soybean crops due to the increased soil mineral N availability by mineralization of soybean residue compared to corn residue. The WCCs can reduce N leaching where baseline NO3-N loads are high in well-drained soils and/or when residual and mineralized N availability is high due to the cropping practices. The findings suggested that WCC implementation plans should be established in watersheds according to local edaphic and agronomic

  4. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay.

    Science.gov (United States)

    Lunn, Nicholas J; Servanty, Sabrina; Regehr, Eric V; Converse, Sarah J; Richardson, Evan; Stirling, Ian

    2016-07-01

    Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture-recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993-1411) in 1987 to 806 (95% BCI = 653-984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001-2010 = 1.02, 95% BCI = 0.98-1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00-1.05) and 0.97 (95% BCI = 0.92-1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations.

  5. Impact of Hurricane Irene on Vibrio vulnificus and Vibrio parahaemolyticus concentrations in surface water, sediment and cultured oysters in the Chesapeake Bay, Maryland, USA

    Directory of Open Access Journals (Sweden)

    Kristi S Shaw

    2014-05-01

    Full Text Available To determine if a storm event (i.e., high winds, large volumes of precipitation could alter concentrations of Vibrio vulnificus and Vibrio parahaemolyticus in aquacultured oysters (Crassostrea virginica and associated surface water and sediment, this study followed a sampling timeline before and after Hurricane Irene impacted the Chesapeake Bay estuary in late August 2011. Aquacultured oysters were sampled from two levels in the water column: surface 0.3 m and near-bottom just above the sediment. Concentrations of each Vibrio spp. and associated virulence genes were measured in oysters with a combination of real-time PCR and most probable number enrichment methods, and in sediment and surface water with real-time PCR. While concentration shifts of each Vibrio species were apparent post-storm, statistical tests indicated no significant change in concentration change for either Vibrio species by location (surface or near bottom oysters or date sampled (oyster tissue, surface water and sediment concentrations. V. vulnificus in oyster tissue was correlated with total suspended solids (r=0.41, p=0.04, and V. vulnificus in sediment was correlated with secchi depth (r=-0.93, p< 0.01, salinity (r=-0.46, p=0.02, tidal height (r=-0.45, p=0.03, and surface water V. vulnificus (r=0.98, p< 0.01. V. parahaemolyticus in oyster tissue did not correlate with environmental measurements, but V. parahaemolyticus in sediment and surface water correlated with several measurements including secchi depth (r=-0.48, p=0.02[sediment]; r=-0.97 p< 0.01[surface water] and tidal height (r=-0.96. p< 0.01[sediment], r=-0.59,p< 0.01 [surface water]. The concentrations of Vibrio spp. were higher in oysters relative to other studies (average V. vulnificus 4x105 MPN g-1, V. parahaemolyticus 1x105 MPN g-1, and virulence-associated genes were detected in most oyster samples. This study provides a first estimate of storm-related Vibrio density changes in oyster tissues, sediment and

  6. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay

    Science.gov (United States)

    Lunn, Nicholas J.; Servanty, Sabrina; Regehr, Eric V.; Converse, Sarah J.; Richardson, Evan S.; Stirling, Ian

    2016-01-01

    Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture–recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993–1411) in 1987 to 806 (95% BCI = 653–984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001–2010 = 1.02, 95% BCI = 0.98–1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00–1.05) and 0.97 (95% BCI = 0.92–1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations.

  7. Evaluation of Salinity-Related Habitat Impacts in the Lower Chesapeake Bay and James River for the Norfolk Harbor and Channels Deepening Study.

    Science.gov (United States)

    1984-10-01

    and by two protozoan parasites , Minchinia nelsoni ("MSX") and Perkinsus marinus ("dermo"). Salinity Relationships - Crassostrea virginica is an...affecting density and abundance of oysters in Chesapeake Bay are predation and disease (actually, protozoan parasites ). Minchinia nelsoni ("MSX") was

  8. Bayes Multiple Decision Functions

    CERN Document Server

    Wu, Wensong

    2011-01-01

    This paper deals with the problem of simultaneously making many (M) binary decisions based on one realization of a random data matrix X. M is typically large and X will usually have M rows associated with each of the M decisions to make, but for each row the data may be low dimensional. A Bayesian decision-theoretic approach for this problem is implemented with the overall loss function being a cost-weighted linear combination of Type I and Type II loss functions. The class of loss functions considered allows for the use of the false discovery rate (FDR), false nondiscovery rate (FNR), and missed discovery rate (MDR) in assessing the decision. Through this Bayesian paradigm, the Bayes multiple decision function (BMDF) is derived and an efficient algorithm to obtain the optimal Bayes action is described. In contrast to many works in the literature where the rows of the matrix X are assumed to be stochastically independent, we allow in this paper a dependent data structure with the associations obtained through...

  9. Low temperature impact testing of welded structural wrought iron

    Science.gov (United States)

    Rogers, Zachary

    During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure

  10. Structural Intensity Characterization of Composite Laminates Subjected to Impact Load

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-fang; HE Peng-fei; LIU Zi-shun

    2008-01-01

    Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions wasanalyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity wasevaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates werediscussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that ofthe steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the compositelaminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten thanthat of the steel plates.

  11. 渤海湾盆地变换构造特征及其成藏意义%Transfer structure and its relation to hydrocarbon exploration in Bohai Bay Basin

    Institute of Scientific and Technical Information of China (English)

    杨明慧

    2009-01-01

    On the basis of the previous classification research, the features of transfer structure in Bohai Bay Basin were analyzed. The transfer structures in Bohai Bay Basin can be divided into two styles of transfer zone and transfer fault according to the connec-tion or non-connection status. The transfer structure in Bohai Bay Basin is mainly exhibited in the style of transfer zone, especially in basin or depression, while the transfer fault only militates in the sag-control level. With the occasional development of transfer fault, most of high-level transfer zones are horizontally connected with different relay ramps. These strike transfer structures in NWW-NW direction are the most important structure styles to control the "north-south segmentation" tectonic framework in Bohai Bay Basin. The difference of oil and gas reserves in Bohai Bay Basin is related to the distribution of prolific hydrocarbon depressions and sags controlled by transfer structure. The paleotopography and rich-sand drainage channels controlled by transfer structure are favorable to the formation of lithologic reservoirs. The adjacent zones of the transfer structure are the important regions for finding the buried-hill structure reservoirs.%依据前人对变换构造的分类研究,分析了渤海湾盆地变换构造的特征.将渤海湾盆地变换构造分为变换带和变换断层两种类型:一般表现为变换带样式,尤其是在盆地或坳陷层次;而变换断层仅在局部的控凹层次上有所体现.高级别的变换带大多数是由一系列不同类型的传递斜坡横向串联而成,间或发育变换断层.北西西-北西向的变换构造是渤海湾盆地"南北分块"构造格局的主控构造样式,而渤海湾盆地油气储量的差异与变换构造控制的富生烃凹陷及洼陷分布有关.变换构造控制的古地形和富砂水系通道有利于形成岩性油气藏,变换构造邻区的高部位则是发现(潜山)构造油气藏的重要地区.

  12. Impact of structural heterogeneity in solar absorber layers (Conference Presentation)

    Science.gov (United States)

    Toney, Michael

    2016-09-01

    Impact of structural heterogeneity in solar absorber layers Michael F Toney SLAC National Accelerator Laboratory Structural and morphological heterogeneity is common in thin film and emerging solar cell absorber layers, including organic photovoltaic bulk heterojunctions (OPV BHJs), hybrid organic-inorganic perovskites (HOIP), and Cu2ZnSn(S,Se)4 (CZTSSe), and has a significant impact on the (opto)electronic heterogeneity and hence absorber properties. In this talk I will use X-ray based methods, including scattering and spectroscopies, to characterize and quantify the heterogeneity in OPV BHJs and HOIP absorber layers. The BHJ films are blends of the small molecule X2 and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) where it has been established that there are three distinct region of the films - pure PC71BM, pure X2 and intimately mixed X2:PC71BM. This talk will show how the absolute concentration of the mixed phase can be used to explain the large PC71BM:X2 composition range where good performance is observed [1]. The talk will also show that spin cast CH3NH3PbI3 films consistent of both crystalline and amorphous regions, which can explain previous heterogeneity in the PL imaging [2]. [1] Huang et al., Adv. Energy Mater. 4, 1301886 (2014). [2] deQuilettes et al., Science 348, 683 (2015).

  13. Impact of methionine oxidation on calmodulin structural dynamics

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, Megan R.; Thompson, Andrew R.; Nitu, Florentin [Biochemistry, Molecular Biology and Biophysics Department, University of Minnesota, Minneapolis, MN 55455 (United States); Moen, Rebecca J. [Chemistry and Geology Department, Minnesota State University, Mankato, MN 56001 (United States); Olenek, Michael J. [Biology Department, University of Wisconsin, La Crosse, WI 54601 (United States); Klein, Jennifer C., E-mail: jklein@uwlax.edu [Biology Department, University of Wisconsin, La Crosse, WI 54601 (United States); Thomas, David D., E-mail: ddt@umn.edu [Biochemistry, Molecular Biology and Biophysics Department, University of Minnesota, Minneapolis, MN 55455 (United States)

    2015-01-09

    Highlights: • We measured the distance distribution between two spin labels on calmodulin by DEER. • Two structural states, open and closed, were resolved at both low and high Ca. • Ca shifted the equilibrium toward the open state by a factor of 13. • Methionine oxidation, simulated by glutamine substitution, decreased the Ca effect. • These results have important implications for aging in muscle and other tissues. - Abstract: We have used electron paramagnetic resonance (EPR) to examine the structural impact of oxidizing specific methionine (M) side chains in calmodulin (CaM). It has been shown that oxidation of either M109 or M124 in CaM diminishes CaM regulation of the muscle calcium release channel, the ryanodine receptor (RyR), and that mutation of M to Q (glutamine) in either case produces functional effects identical to those of oxidation. Here we have used site-directed spin labeling and double electron–electron resonance (DEER), a pulsed EPR technique that measures distances between spin labels, to characterize the structural changes resulting from these mutations. Spin labels were attached to a pair of introduced cysteine residues, one in the C-lobe (T117C) and one in the N-lobe (T34C) of CaM, and DEER was used to determine the distribution of interspin distances. Ca binding induced a large increase in the mean distance, in concert with previous X-ray crystallography and NMR data, showing a closed structure in the absence of Ca and an open structure in the presence of Ca. DEER revealed additional information about CaM’s structural heterogeneity in solution: in both the presence and absence of Ca, CaM populates both structural states, one with probes separated by ∼4 nm (closed) and another at ∼6 nm (open). Ca shifts the structural equilibrium constant toward the open state by a factor of 13. DEER reveals the distribution of interprobe distances, showing that each of these states is itself partially disordered, with the width of each

  14. The K/T-boundary carbonate breccia succession at the Cantarell Field, Campeche Bay area: a representative example of the influence of the Chicxulub meteorite-impact event on the formation of extraordinary petroleum reservoirs

    Science.gov (United States)

    Murillo-Muñeton, G.; Grajales-Nishimura, J. M.; Velasquillo-Martínez, L. G.; García-Hernández, J.

    2013-05-01

    Over the last decade, intense petroleum exploration and exploitation activities have been conducted in the Campeche Bay area. Detailed stratigraphic studies in this region based on seismic, well logs, and core data have allowed the documentation of numerous deep-water carbonate breccia deposits throughout the Cretaceous stratigraphic column. However, the uppermost carbonate breccia succession is very distinctive in terms of its sedimentological properties compared to the underlying and older calcareous breccia layers. The unique characteristics of this deposit include: its unusual thickness, stratigraphic position, distribution, and content of impact-metamorphic constituents. At the Cantarell field, this carbonate breccia sedimentary package is a representative example of how the Chuxulub meteorite-impact event influenced the formation of a remarkable carbonate reservoir. This deposit was the most important oil-producing stratigraphic horizon for long time in that field. Nevertheless, this reservoir is still important not only in that field but also in other fields in offshore Campeche. The K/T boundary carbonate breccia succession is a typical fining-upward deposit made up, from base to top, of three units. The 50 to 300-m thick, basal Unit 1 consists of a coarse-grained carbonate breccia. Unit 2 is a 10 to 20 m-thick, fine-grained carbonate breccia. The 25 to 30 m-thick, uppermost Unit 3 is a greenish interval of friable sand, silt and clay-sized constituents with abundant ejecta material. In some wells, a 10 to 20 m-thick, non-oil producing fine-grained calcareous breccia occurs interbedded within Unit 3. The K/T boundary carbonate sedimentary package is underlain and overlain by deep-water shaly calcareous facies of Upper Maastrichtian and Lower Paleocene age, respectively. Studies of cronostratigraphic-equivalent outcrop analogs of this K/T boundary carbonate reservoir carried out by the authors in the Sierra de Chiapas (El Guayal, Tabasco and Bochil, Chiapas

  15. Impact of Methionine Oxidation on Calmodulin Structural Dynamics

    Science.gov (United States)

    McCarthy, Megan R.; Thompson, Andrew R.; Nitu, Florentin; Moen, Rebecca J.; Olenek, Michael J.; Klein, Jennifer C.; Thomas, David D.

    2014-01-01

    We have used electron paramagnetic resonance (EPR) to examine the structural impact of oxidizing specific methionine (M) side chains in calmodulin (CaM). It has been shown that oxidation of either M109 or M124 in CaM diminishes CaM regulation of the muscle calcium release channel, the ryanodine receptor (RyR), and that mutation of M to Q (glutamine) in either case produces functional effects identical to those of oxidation. Here we have used site-directed spin labeling and double electron-electron resonance (DEER), a pulsed EPR technique that measures distances between spin labels, to characterize the structural changes resulting from these mutations. Spin labels were attached to a pair of introduced cysteine residues, one in the C-lobe (T117C) and one in the N-lobe (T34C) of CaM, and DEER was used to determine the distribution of interspin distances. Ca binding induced a large increase in the mean distance, in concert with previous x-ray crystallography and NMR data, showing a closed structure in the absence of Ca and an open structure in the presence of Ca. DEER revealed additional information about CaM’s structural heterogeneity in solution: In both the presence and absence of Ca, CaM populates both structural states, one with probes separated by ~4 nm (closed) and another at ~6 nm (open). Ca shifts the structural equilibrium constant toward the open state by a factor of 13. DEER reveals the distribution of interprobe distances, showing that each of these states is itself partially disordered, with the width of each population ranging from 1.5 to 3 nm. Both mutations (M109Q and M124Q) decrease the effect of Ca on the structure of CaM, primarily by decreasing the closed-to-open equilibrium constant in the presence of Ca. We propose that Met oxidation alters CaM’s functional interaction with its target proteins by perturbing this Ca-dependent structural shift. PMID:25478640

  16. Nelson River and Hudson Bay

    Science.gov (United States)

    2002-01-01

    Rivers that empty into large bodies of water can have a significant impact on the thawing of nearshore winter ice. This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2001, shows the Nelson River emptying spring runoff from the Manitoba province to the south into the southwestern corner of Canada's Hudson Bay. The warmer waters from more southern latitudes hasten melting of ice near the shore, though some still remained, perhaps because in shallow coastal waters, the ice could have been anchored to the bottom. High volumes of sediment in the runoff turned the inflow brown, and the rim of the retreating ice has taken on a dirty appearance even far to the east of the river's entrance into the Bay. The sediment would have further hastened the melting of the ice because its darker color would have absorbed more solar radiation than cleaner, whiter ice. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  17. Bayes multiple decision functions.

    Science.gov (United States)

    Wu, Wensong; Peña, Edsel A

    2013-01-01

    This paper deals with the problem of simultaneously making many (M) binary decisions based on one realization of a random data matrix X. M is typically large and X will usually have M rows associated with each of the M decisions to make, but for each row the data may be low dimensional. Such problems arise in many practical areas such as the biological and medical sciences, where the available dataset is from microarrays or other high-throughput technology and with the goal being to decide which among of many genes are relevant with respect to some phenotype of interest; in the engineering and reliability sciences; in astronomy; in education; and in business. A Bayesian decision-theoretic approach to this problem is implemented with the overall loss function being a cost-weighted linear combination of Type I and Type II loss functions. The class of loss functions considered allows for use of the false discovery rate (FDR), false nondiscovery rate (FNR), and missed discovery rate (MDR) in assessing the quality of decision. Through this Bayesian paradigm, the Bayes multiple decision function (BMDF) is derived and an efficient algorithm to obtain the optimal Bayes action is described. In contrast to many works in the literature where the rows of the matrix X are assumed to be stochastically independent, we allow a dependent data structure with the associations obtained through a class of frailty-induced Archimedean copulas. In particular, non-Gaussian dependent data structure, which is typical with failure-time data, can be entertained. The numerical implementation of the determination of the Bayes optimal action is facilitated through sequential Monte Carlo techniques. The theory developed could also be extended to the problem of multiple hypotheses testing, multiple classification and prediction, and high-dimensional variable selection. The proposed procedure is illustrated for the simple versus simple hypotheses setting and for the composite hypotheses setting

  18. Stability of reef framework and post settlement mortality as the structuring factor for recovery of Malakal Bay Reef, Palau, Micronesia: 25 years after a severe COTS outbreak

    Science.gov (United States)

    Victor, Steven

    2008-03-01

    Corals in Malakal Bay reefs were devastated in the 1979 Crown of Thorns Starfish (COTS) outbreak. It has been almost 30 years since the outbreak and coral cover at the study sites have not come close to the cover before the outbreak. A question is asked: what factors may contribute to the slow recovery of these reefs: recruitment or post-settlement mortality? Two habitat types within the reef systems were monitored using coral transplants to determine if corals can survive in these environments and recruitment tiles to see if there are larvae coming into the system. The study revealed that coral survivorship is high in the fore reef areas compared to the reef channel slopes and that larvae is not a limiting factor to natural recovery. Stability of the reef framework, i.e. unstable rubble substrate, and possibly high post settlement mortality, are the structuring factors that determine the recovery process in these reef systems and possibly so for similar habitats in other reef systems throughout Palau.

  19. An age-structured population model for horseshoe crabs in the Delaware Bay area to assess harvest and egg availability for shorebirds

    Science.gov (United States)

    Sweka, J.A.; Smith, D.R.; Millard, M.J.

    2007-01-01

    The objective of this simulation study was to create an age-structured population model for horseshoe crabs (Limulus polyphenols) in the Delaware Bay region using best available estimates of age-specific mortality and recent harvest levels. Density dependence was incorporated using a spatial model relating egg mortality with abundance of spawning females. Combinations of annual female harvest (0, 50, 100, and 200 thousand), timing of female harvest (before or after spawning), and three levels of density-dependent egg mortality were simulated. The probability of the population increasing was high (> 80%) with low and medium egg mortality and harvest less than 200 thousand females per year. Under the high egg mortality case, the probability of the population increasing was < 50% regardless of harvest. Harvest occurring after spawning increased the probability of population growth. The number of eggs available to shorebirds was highest when egg mortality was lowest and female abundance was at its highest levels. Although harvest and egg mortality influenced population growth and food availability to shorebirds, sensitivity and elasticity analyses showed that early-life stage mortality, age 0 mortality in particular, was the most important parameter for population growth. Our modeling results indicate areas where further research is needed and suggest effective management will involve a combination of harvest management and actions to increase early juvenile survival. ?? 2007 Estuarine Research Federation.

  20. MODELING THE 1958 LITUYA BAY MEGA-TSUNAMI, II

    Directory of Open Access Journals (Sweden)

    Charles L. Mader

    2002-01-01

    Full Text Available Lituya Bay, Alaska is a T-Shaped bay, 7 miles long and up to 2 miles wide. The two arms at the head of the bay, Gilbert and Crillon Inlets, are part of a trench along the Fairweather Fault. On July 8, 1958, an 7.5 Magnitude earthquake occurred along the Fairweather fault with an epicenter near Lituya Bay.A mega-tsunami wave was generated that washed out trees to a maximum altitude of 520 meters at the entrance of Gilbert Inlet. Much of the rest of the shoreline of the Bay was denuded by the tsunami from 30 to 200 meters altitude.In the previous study it was determined that if the 520 meter high run-up was 50 to 100 meters thick, the observed inundation in the rest of Lituya Bay could be numerically reproduced. It was also concluded that further studies would require full Navier-Stokes modeling similar to those required for asteroid generated tsunami waves.During the Summer of 2000, Hermann Fritz conducted experiments that reproduced the Lituya Bay 1958 event. The laboratory experiments indicated that the 1958 Lituya Bay 524 meter run-up on the spur ridge of Gilbert Inlet could be caused by a landslide impact.The Lituya Bay impact landslide generated tsunami was modeled with the full Navier- Stokes AMR Eulerian compressible hydrodynamic code called SAGE with includes the effect of gravity.

  1. The Vibration Impact Determination of the Helicopter Structural Components

    Directory of Open Access Journals (Sweden)

    Khaksar Zeinab

    2017-01-01

    Full Text Available This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

  2. Impact of chromatin structures on DNA processing for genomic analyses.

    Directory of Open Access Journals (Sweden)

    Leonid Teytelman

    Full Text Available Chromatin has an impact on recombination, repair, replication, and evolution of DNA. Here we report that chromatin structure also affects laboratory DNA manipulation in ways that distort the results of chromatin immunoprecipitation (ChIP experiments. We initially discovered this effect at the Saccharomyces cerevisiae HMR locus, where we found that silenced chromatin was refractory to shearing, relative to euchromatin. Using input samples from ChIP-Seq studies, we detected a similar bias throughout the heterochromatic portions of the yeast genome. We also observed significant chromatin-related effects at telomeres, protein binding sites, and genes, reflected in the variation of input-Seq coverage. Experimental tests of candidate regions showed that chromatin influenced shearing at some loci, and that chromatin could also lead to enriched or depleted DNA levels in prepared samples, independently of shearing effects. Our results suggested that assays relying on immunoprecipitation of chromatin will be biased by intrinsic differences between regions packaged into different chromatin structures - biases which have been largely ignored to date. These results established the pervasiveness of this bias genome-wide, and suggested that this bias can be used to detect differences in chromatin structures across the genome.

  3. Post-impact hydrothermal system geochemistry and mineralogy: Rochechouart impact structure, France.

    Science.gov (United States)

    Simpson, Sarah

    2014-05-01

    Hypervelocity impacts generate extreme temperatures and pressures in target rocks and may permanently alter them. The process of cratering is at the forefront of research involving the study of the evolution and origin of life, both on Mars and Earth, as conditions may be favourable for hydrothermal systems to form. Of the 170 known impact structures on Earth, over one-third are known to contain fossil hydrothermal systems [1]. The introduction of water to a system, when coupled with even small amounts of heat, has the potential to completely alter the target or host rock geochemistry. Often, the mineral assemblages produced in these environments are unique, and are useful indicators of post-impact conditions. The Rochechouart impact structure in South-Central France is dated to 201 ± 2 Ma into a primarily granitic target [2]. Much of the original morphological features have been eroded and very little of the allochthonous impactites remain. This has, however, allowed researchers to study the shock effects on the lower and central areas of the structure, as well as any subsequent hydrothermal activity. Previous work has focused on detailed classification of the target and autochthonous and allochthonous impactites [3, 4], identification of the projectile [5], and dating the structure using Ar-isotope techniques [2]. Authors have also noted geochemical evidence of K-metasomatism, which is pronounced throughout all lithologies as enrichment in K2O and depletion in CaO and Na2O [3, 4, 5]. This indicates a pervasive hydrothermal system, whose effects throughout the structure have yet to be studied in detail, particularly in those parts at and below the transient floor. The purpose of this study is to classify the mineralogical and geochemical effects of the hydrothermal system. Samples were collected via permission from the Réserve Naturelle de l'Astroblème de Rochechouart-Chassenon [6]. Sample selection was based on the presence of secondary mineralization in hand

  4. FLOW STRUCTURE AND SEDIMENT TRANSPORT WITH IMPACTS OF AQUATIC VEGETATION

    Institute of Scientific and Technical Information of China (English)

    LIU Cheng; SHEN Yong-ming

    2008-01-01

    Aquatic vegetation plays an important role in the flow structure of open channels and thus changes the fate and the transport of sediment. This article proposes a three-dimensional turbulence model by introducing vegetation density and drag force into the control equations of water flow in the presence of vegetation. The model was used to calculate the impacts of submerged vegetation on the vertical profiles of longitudinal flow velocities, the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain, the removal of suspended sediment from the channels by emergent vegetation, and the bed changes around and in a vegetated island. Numerical investigations show that aquatic vegetation retards flow in the vegetation zone, reduces the sediment transport capacity, and contributes to erosion on both sides of the vegetated island. Calculated results agree well with experimental results.

  5. Impact of structural characteristics on starch digestibility of cooked rice.

    Science.gov (United States)

    Tamura, Masatsugu; Singh, Jaspreet; Kaur, Lovedeep; Ogawa, Yukiharu

    2016-01-15

    To examine the impact of structural characteristics of cooked rice grains on their starch digestibility, a simulated in vitro gastro-small intestinal digestion technique was applied to intact and homogenised cooked rice samples. The starch hydrolysis percentage increased during simulated small intestinal digestion, in which approximately 65% and 24% of the starch was hydrolysed within the first 5min, for homogenised and intact cooked rice, respectively. The kinetic constant of homogenised cooked rice, which was regarded as an estimated digestion rate, was ∼8 times higher than the intact cooked rice. The homogenised and intact samples were also examined for any microstructural changes occurring during the in vitro digestion process using fluorescent and scanning electron microscopy. In the intact samples, the aleurone layers of the endosperm remained as thin-film like layers during in vitro digestion and thus may be regarded as less digestible materials that influence cooked rice digestibility.

  6. The Ecology of Seamounts: Structure, Function, and Human Impacts

    Science.gov (United States)

    Clark, Malcolm R.; Rowden, Ashley A.; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I.; Rogers, Alex D.; O'Hara, Timothy D.; White, Martin; Shank, Timothy M.; Hall-Spencer, Jason M.

    2010-01-01

    In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.

  7. Car Side Structure Crashworthiness in Pole and Moving Deformable Barrier Side Impacts

    Institute of Scientific and Technical Information of China (English)

    WANG Dazhi; DONG Guang; ZHANG Jinhuan; HUANG Shilin

    2006-01-01

    To clearly understand passenger car structure's crashworthiness in typical side impacts of pole and moving deformable barrier (MDB) impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the pole side impact according to European New Car Assessment Program (EuroNCAP) and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger's head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.

  8. Southern Monterey Bay Littoral Cell CRSMP Proposed Receiver Site 2008

    Data.gov (United States)

    California Department of Resources — Given the location of the critical areas of erosion and the need to avoid adverse impacts to local sensitive habitat, the Southern Monterey Bay Coastal RSM Plan...

  9. Lithospheric Architecture Beneath Hudson Bay

    Science.gov (United States)

    Porritt, R. W.; Miller, M. S.; Darbyshire, F. A.

    2015-12-01

    Hudson Bay overlies some of the thickest Precambrian lithosphere on Earth, whose internal structures contain important clues to the earliest workings of plate formation. The terminal collision, the Trans-Hudson Orogen, brought together the Western Churchill craton to the northwest and the Superior craton to the southeast. These two Archean cratons along with the Paleo-Proterozoic Trans-Hudson internides, form the core of the North American craton. We use S to P converted wave imaging and absolute shear velocity information from a joint inversion of P to S receiver functions, new ambient noise derived phase velocities, and teleseismic phase velocities to investigate this region and determine both the thickness of the lithosphere and the presence of internal discontinuities. The lithosphere under central Hudson Bay approaches 􏰂350 km thick but is thinner (􏰂200-250 km) around the periphery of the Bay. Furthermore, the amplitude of the lithosphere-asthenosphere boundary (LAB) conversion from the S receiver functions is unusually large for a craton, suggesting a large thermal contrast across the LAB, which we interpret as direct evidence of the thermal insulation effect of continents on the asthenosphere. Within the lithosphere, midlithospheric discontinuities, significantly shallower than the base of the lithosphere, are often imaged, suggesting the mechanisms that form these layers are common. Lacking time-history information, we infer that these discontinuities reflect reactivation of formation structures during deformation of the craton.

  10. CASCO BAY PLAN

    Science.gov (United States)

    Casco Bay lies at the heart of Maine's most populated area. The health of its waters, wetlands, and wildlife depend in large part on the activities of the quarter-million residents who live in its watershed. Less than 30 years ago, portions of Casco Bay were off-limits to recr...

  11. Energy profile and secondary structure impact shRNA efficacy

    Directory of Open Access Journals (Sweden)

    Zeng Xiao

    2009-07-01

    Full Text Available Abstract Background RNA interference (RNAi is a cellular mechanism in which a short/small double stranded RNA induces the degradation of its sequence specific target mRNA, leading to specific gene silencing. Since its discovery, RNAi has become a powerful biological technique for gene function studies and drug discovery. The very first requirement of applying RNAi is to design functional small interfering RNA (siRNA that can uniquely induce the degradation of the targeted mRNA. It has been shown that many functional synthetic siRNAs share some common characteristics, such as GC content limitation and free energy preferences at both terminals, etc. Results Our three-phase algorithm was developed to design siRNA on a whole-genome scale based on those identified characteristics of functional siRNA. When this algorithm was applied to design short hairpin RNA (shRNA, the validated success rate of shRNAs was over 70%, which was almost double the rate reported for TRC library. This indicates that the designs of siRNA and shRNA may share the same concerns. Further analysis of the shRNA dataset of 444 designs reveals that the high free energy states of the two terminals have the largest positive impact on the shRNA efficacy. Enforcing these energy characteristics of both terminals can further improve the shRNA design success rate to 83.1%. We also found that functional shRNAs have less probability for their 3' terminals to be involved in mRNA secondary structure formation. Conclusion Functional shRNAs prefer high free energy states at both terminals. High free energy states of the two terminals were found to be the largest positive impact factor on shRNA efficacy. In addition, the accessibility of the 3' terminal is another key factor to shRNA efficacy.

  12. Groundwater Coastal Discharge at the Kalogrias Bay in Mani and its Relationship with the Geological and Tectonic Structure of Taygetos (Mani, Southern Peloponnese- Greece)

    Science.gov (United States)

    Migiros, George; Papanikolaou, Ioannis

    2010-05-01

    . c) All springs that are developed towards the lowland areas, the shoreline and predominantly offshore, where the major gushing spring of Kalogrias bay emerge, are directly related to the karstic hydrological pattern of the Taygetos Mountain. This karstic path is highly related to the tectonic structures and in particular: a) towards the mountain area it follows the anticline megastructures with a N-S trending fold axis that is plunging towards south; b) towards the hilly area and the lower slopes it strikes west following the transverse fault structures that form oblique normal faults that are E-W trending; c) towards the lowland, shoreline and offshore area the karstic water produces gushing springs along strike the NNW-SSE trending normal faults that were formed during the recent extensional field and predominantly towards their intersection points with the transverse E-W trending oblique normal faults. In conclusion, these pathways that are tectonically controlled, are used by the karstic systems that have been mapped and discharge the karstic water flow westwards towards the Messiniakos Gulf.

  13. Comparison of Response between RC and SC Containment Structures Subjected to Aircraft Impact

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sang Shup; Choi, In Kil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Tae Hyo [Hanyang University, Seoul (Korea, Republic of)

    2012-05-15

    Since the aircraft terror to the World Trade Center (WTC) on September 11, 2001, an aircraft impact problem has been increasingly interested. The possibilities of aircraft impacts against nuclear power plants are one of important category. To date, the impact load of the analysis on aircraft impacts has been applied to target structures in local areas by using the impact force-time history function of Riera. However, Riera forcing function is not recommended at the expectation of unreasonable damage or perforation to target structures. The numerical analysis of rc and sc containment structures subjected to aircraft impact is performed by using the AUTODYN-3D. It is carried out the four different types for RC and SC structures. Thus, in this study, the different behaviors of containment structures and the safety of SC structure are expected

  14. Experimental Study and Numerical Simulation of Hypervelocity Projectile Impact on Double-Wall Structure

    Institute of Scientific and Technical Information of China (English)

    陈沿海; 张庆明; 黄风雷

    2004-01-01

    Tests of hypervelocity projectile impact on double-wall structure were performed with the front wall ranging from 0.5 mm to 2.0 mm thick and different impact velocities. Smooth particle hydrodynamics (SPH) code in LS-DYNA was employed for the simulation of hypervelocity impact on the double-wall structure. By using elementary shock wave theory, the experimental results above are analyzed. The analysis can provide an explanation for the penetration mechanism of hypervelocity projectile impact on double-wall structure about the effect of front wall thickness and impact velocity.

  15. Mapping Oyster Reef Habitats in Mobile Bay

    Science.gov (United States)

    Bolte, Danielle

    2011-01-01

    Oyster reefs around the world are declining rapidly, and although they haven t received as much attention as coral reefs, they are just as important to their local ecosystems and economies. Oyster reefs provide habitats for many species of fish, invertebrates, and crustaceans, as well as the next generations of oysters. Oysters are also harvested from many of these reefs and are an important segment of many local economies, including that of Mobile Bay, where oysters rank in the top five commercial marine species both by landed weight and by dollar value. Although the remaining Mobile Bay oyster reefs are some of the least degraded in the world, projected climate change could have dramatic effects on the health of these important ecosystems. The viability of oyster reefs depends on water depth and temperature, appropriate pH and salinity levels, and the amount of dissolved oxygen in the water. Projected increases in sea level, changes in precipitation and runoff patterns, and changes in pH resulting from increases in the amount of carbon dioxide dissolved in the oceans could all affect the viability of oyster reefs in the future. Human activities such as dredging and unsustainable harvesting practices are also adversely impacting the oyster reefs. Fortunately, several projects are already under way to help rebuild or support existing or previously existing oyster reefs. The success of these projects will depend on the local effects of climate change on the current and potential habitats and man s ability to recognize and halt unsustainable harvesting practices. As the extent and health of the reefs changes, it will have impacts on the Mobile Bay ecosystem and economy, changing the resources available to the people who live there and to the rest of the country, since Mobile Bay is an important national source of seafood. This project identified potential climate change impacts on the oyster reefs of Mobile Bay, including the possible addition of newly viable

  16. Impact of Corrugated Paperboard Structure on Puncture Resistance

    Directory of Open Access Journals (Sweden)

    Vaidas Bivainis

    2015-03-01

    Full Text Available Thanks to its excellentprotective properties, lightness, a reasonable price, and ecology, corrugated paperboardis one of the most popular materials used in the production of packaging for variousproducts. During transportation or storage, packaging with goods can be exposedto the mass of other commodities, dropping from heights and transportationshock loads, which can lead to their puncture damage. Depending on the purposeand size of the packaging, the thickness, grammage, constituent paper layers,numbers of layers and type of fluting of corrugated paperboard used in itsproduction differ. A standard triangular prism, corrugated paperboard fixationplates and a universal tension-compression machine were used to investigate theimpact of corrugated paperboard structure and other parameters on the punctureresistance of the material. The investigation determines the maximum punctureload and estimates energy required to penetrate the corrugated paperboard. Itwas found that the greatest puncture resistance is demonstrated by paperboardwith a larger number of corrugating flutings and the board produced from harderpaper with a smaller amount of recycled paper. It was established that thegrammage of three-layered paperboard with two different fluting profiles has thegreatest impact on the level of static puncture energy.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5713

  17. Impact of Demographic Structure on Paddy and Forestland Management

    Institute of Scientific and Technical Information of China (English)

    LI Tiehua; XIANG Wenhua; XU Guozhen; ZENG Guangzheng

    2006-01-01

    In order to understand the impact of demographic structure on paddy and forestland management after the convening of the Third Plenary Session of the 11"1 CPC (Communist Party of China) Central Committee and the implementation of the Household Responsibility System (the government divided up land among peasants for cultivating and the peasants sell a set part of their produced goods to the government at stipulated prices by contract in the countryside of China), 147 households in 6 villages, belonging to Xiangtan County and Zhuzhou County in Hunan Province, were selected as research samples, and interview, questionnaire survey and second hand data analyzing were used as the methods. The results showed: Persons with different ages had different ideas, and young peasants would like to work in towns or cities for more income, so they used and depended on land less; In terms of sex, the male was still the main user of land, and therefore the ability, idea and activity of male played an important role in land management; Generally, the labors with better educational background grasped more knowledge and technologies, and they had more opportunity to get jobs and had better working condition and more income in town or cities, so they depended on and used land less.

  18. Characteristic mixing triangles in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.; Sastry, J.S.

    Temperature-salinity structures in the inner part of Bay of Bengal showed complete mixing processes in the upper bay, less than about 600 m can be characterisEd. by a mixing triangle constitutEd. by three characteristic water properties. In outer...

  19. Comparison of petrophysical properties of impactites for four meteoritic impact structures

    Science.gov (United States)

    Popov, Y.; Mayr, S.; Romushkevich, R.; Burkhardt, H.; Wilhelm, H.

    2014-05-01

    We reanalyzed and compared unique data sets, which we obtained in the frame of combined petrophysical and geothermal investigations within scientific drilling projects on four impact structures: the Puchezh-Katunki impact structure (Vorotilovo borehole, Russia), the Ries impact structure (Noerdlingen-73 borehole, Germany), the Chicxulub impact structure (ICDP Yaxcopoil-1 borehole, Mexico), and the Chesapeake impact structure (ICDP-USGS-Eyreville borehole, USA). For a joined interpretation, we used the following previously published data: thermal properties, using the optical scanning technique, and porosities, both measured on densely sampled halfcores of the boreholes. For the two ICDP boreholes, we also used our previously published P-wave velocities measured on a subset of cores. We show that thermal conductivity, thermal anisotropy, porosity, and velocity can be correlated with shock metamorphism (target rocks of the Puchezh-Katunki and Ries impact structures), and confirm the absence of shock metamorphism in the samples taken from megablocks (Chicxulub and Chesapeake impact structure). The physical properties of the lithic impact breccias and suevites are influenced mainly by their impact-related porosity. Physical properties of lower porosity lithic impact breccias and suevites are also influenced by their chemical composition. These data allow for a distinction between different types of breccias due to differences concerning the texture and chemistry and the different amounts of melt and rock clasts.

  20. Mesozooplankton community structure in the upper 1,000 m along the western Bay of Bengal during the 2002 fall intermonsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, V.; Ramaiah, N.

    copepod diversity throughout upper 1,000 m of the western Bay is attributed to the moderate oligotrophy. We reported 93 copepod species for the first time from this region, from which 7 are first records for the Indian Ocean. Cold-core eddies seem to play...

  1. Comparison of the frequentist properties of Bayes and the maximum likelihood estimators in an age-structured fish stock assessment model

    DEFF Research Database (Denmark)

    Nielsen, Anders; Lewy, Peter

    2002-01-01

    A simulation study was carried out for a separable fish stock assessment model including commercial and survey catch-at-age and effort data. All catches are considered stochastic variables subject to sampling and process variations. The results showed that the Bayes estimator of spawning biomass ...

  2. Using remote sensing technique for analyzing temporal changes of seagrass beds by human impacts in waters of Cam Ranh Bay, Vietnam

    Science.gov (United States)

    Minh Thu, Phan; Hoang Son, Tong Phuoc; Komatsu, Teruhisa

    2012-10-01

    Seagrass beds/meadows are very productive ecosystems with high biodiversities. However, they have been degraded under high pressures of human activities. Combining depth-invariance index and ground-truthing, distribution of seagrass beds in Cam Ranh Bay was identified by analyses of multi-remote sensing images such as LANDSAT, SPOT and ALOS AVNIR-2. Although coverage of seagrass meadows was1178 ha, the seagrass meadows were being degraded by illegal fishing methods, aquaculture and discharges from industries and living domestics. The reducing ratio of seagrass coverage has been increased in recent years. While the depth-invariance index method would help to detect the areas of seagrass beds, this method requires combination of field trip and absorption library methods to increase classification accuracy. Final maps of the status and changes of seagrass beds could help to integrate the sustainable development of economy with protection of natural resources.

  3. Spatial impacts of urban structures on micrometeorological variables

    Science.gov (United States)

    Koelbing, Merle; Schuetz, Tobias; Weiler, Markus

    2016-04-01

    The heterogeneity of urban surfaces including buildings and the urban vegetation causes high variability of micrometeorological variables on small spatial scales which makes it hard to observe or even predict climate conditions and in particular evapotranspiration with high resolution on the scale of entire cities. Regarding future climate changes and their impacts on urban climate and hydrology the predictability of these small scale variations becomes more and more relevant i.e. for city planners to improve the development of appropriate mitigation strategies. Therefore, new transfer functions for meteorological variables are needed, which consider the structural variability in urban areas and its impacts on the energy balance (shading effects, ventilation, lateral longwave energy fluxes). We approach this goal by testing a mobile meteorological station (the station is mounted on a bicycle trailer and transported by an E-Bike) as a means to derive empirical spatial transfer functions for specific urban structures. We observe air temperature and relative air humidity at 2 different heights, wind direction and speed, incoming and outgoing shortwave radiation as well as infrared temperature from above and below and the four directions. First measurements have been performed in December 2015 at 22 locations in four clusters, which represent manifold different characteristics of urban areas within the city of Freiburg. Every location has been monitored two to six times. Overall, nearly 200 measurements of each variable have been taken. Each measurement takes five minutes. Values are logged every 15 seconds. These measurements were analyzed with regard to a climate station mounted on a rooftop in the proximity of all clusters. Results show a systematic pattern in the differences between the values taken with the fixed and those taken with the mobile climate station, depending on the measurement locations. For example, lower air temperature and higher relative air

  4. Probability of Detection Study on Impact Damage to Honeycomb Composite Structure using Thermographic Inspection

    Science.gov (United States)

    Hodge, Andrew J.; Walker, James L., II

    2008-01-01

    A probability of detection study was performed for the detection of impact damage using flash heating infrared thermography on a full scale honeycomb composite structure. The honeycomb structure was an intertank structure from a previous NASA technology demonstration program. The intertank was fabricated from IM7/8552 carbon fiber/epoxy facesheets and aluminum honeycomb core. The intertank was impacted in multiple locations with a range of impact energies utilizing a spherical indenter. In a single blind study, the intertank was inspected with thermography before and after impact damage was incurred. Following thermographic inspection several impact sites were sectioned from the intertank and cross-sectioned for microscopic comparisons of NDE detection and actual damage incurred. The study concluded that thermographic inspection was a good method of detecting delamination damage incurred by impact. The 90/95 confidence level on the probability of detection was close to the impact energy that delaminations were first observed through cross-sectional analysis.

  5. 16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT... 1 to Subpart A of Part 1201—Glass Impact Test Structure EC03OC91.004...

  6. The Structure of Arizaro, Salta, Argentina: A New Simple Type Meteorite Impact Site?

    Science.gov (United States)

    Acevedo, R. D.; Rocca, M.; Alonso, R.; Rabassa, J.; Ponce, J. F.; Klajnik, K.

    2012-09-01

    A possible new impact crater had been found in Puna, Argentina: the structure of Arizaro (24º 55" 45.30” S, 67º 27" 09.64” W), located at 3,650 m.a.s.l. This structure is probably a new young simple-type impact crater on Tertiary-Quaternary sedimentary deposits.

  7. Hammond Bay Biological Station

    Data.gov (United States)

    Federal Laboratory Consortium — Hammond Bay Biological Station (HBBS), located near Millersburg, Michigan, is a field station of the USGS Great Lakes Science Center (GLSC). HBBS was established by...

  8. Bathymetry in Jobos Bay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 4x4 meter resolution bathymetric surface for Jobos Bay, Puerto Rico (in NAD83 UTM 19 North). The depth values are in meters referenced to the...

  9. Biscayne Bay Alongshore Epifauna

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Field studies to characterize the alongshore epifauna (shrimp, crabs, echinoderms, and small fishes) along the western shore of southern Biscayne Bay were started in...

  10. Humboldt Bay Orthoimages

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of 0.5-meter pixel resolution, four band orthoimages covering the Humboldt Bay area. An orthoimage is remotely sensed image data in which...

  11. Lagrangian transport in a microtidal coastal area: the Bay of Palma, island of Mallorca, Spain

    Directory of Open Access Journals (Sweden)

    I. Hernández-Carrasco

    2013-10-01

    Full Text Available Coastal transport in the Bay of Palma, a small region in the island of Mallorca, Spain, is characterized in terms of Lagrangian descriptors. The data sets used for this study are the output for two months (one in autumn and one in summer of a high resolution numerical model, ROMS (Regional Ocean Model System, forced atmospherically and with a spatial resolution of 300 m. The two months were selected because of their different wind regime, which is the main driver of the sea dynamics in this area. Finite-size Lyapunov exponents (FSLEs were used to locate semi-persistent Lagrangian coherent structures (LCS and to understand the different flow regimes in the bay. The different wind directions and regularity in the two months have a clear impact on the surface bay dynamics, whereas only topographic features appear clearly in the bottom structures. The fluid interchange between the bay and the open ocean was studied by computing particle trajectories and residence time (RT maps. The escape rate of particles out of the bay is qualitatively different, with a 32% greater escape rate of particles to the ocean in October than in July, owing to the different geometric characteristics of the flow. We show that LCSs separate regions with different transport properties by displaying spatial distributions of residence times on synoptic Lagrangian maps together with the location of the LCSs. Correlations between the time-dependent behavior of FSLE and RT are also investigated, showing a negative dependence when the stirring characterized by FSLE values moves particles in the direction of escape.

  12. eBay.com

    DEFF Research Database (Denmark)

    Engholm, Ida

    2014-01-01

    Celebrated as one of the leading and most valuable brands in the world, eBay has acquired iconic status on par with century-old brands such as Coca-Cola and Disney. The eBay logo is now synonymous with the world’s leading online auction website, and its design is associated with the company......’s purpose: selling millions of goods, some of which are ‘designer’ items and some of which are considered design icons....

  13. Core Perylene Diimide Designs via Direct Bay and Ortho (Poly)trifluoromethylation: Synthesis, Isolation, X-ray Structures, Optical and Electronic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Clikeman, Tyler T.; Bukovsky, Eric V.; Wang, Xue B.; Chen, Yu-Sheng; Rumbles, Garry; Strauss, Steven H.; Boltalina, Olga V.

    2015-09-22

    We developed an efficient solvent- and catalyst-free direct polytrifluoromethylation of solid perylene-3,4,9,10-tetracarboxylic dianhydride that produced a new family of (poly)perfluoroalkyl bay and ortho substituted PDIs with two different imide substituents. Direct hydrogen substitution with CN group led to the synthesis of a cyanated perfluoroalkyl PDI derivative for the first time. Absorption, steady-state and time-resolved emission, X-ray diffraction, electrochemical, and gas-phase electron affinity data allowed for systematic studies of substitution effects at bay, ortho, and imide positions in the new PDIs. Solid-state packing showed remarkable variations in the intermolecular interactions that are important for charge transport and photophysical properties. Analysis of the electrochemical data for 143 electron poor PDIs, including newly reported compounds, revealed some general trends and peculiar effects of electron withdrawing group substitution at all three positions.

  14. Core Perylene Diimide Designs via Direct Bay- and ortho-(Poly)trifluoromethylation: Synthesis, Isolation, X-Ray Structures, Optical and Electronic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Clikeman, Tyler T. [Colorado State Univ., Fort Collins, CO (United States); Bukovsky, Eric V. [Colorado State Univ., Fort Collins, CO (United States); Wang, Xue-Bin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chen, Yu-Sheng [Univ. of Chicago, IL (United States); Rumbles, Garry [National Renewable Energy Lab. (NREL), Golden, CO (United States); Strauss, Steven H. [Colorado State Univ., Fort Collins, CO (United States); Boltalina, Olga V. [Colorado State Univ., Fort Collins, CO (United States)

    2015-09-22

    We developed an efficient solvent- and catalyst-free direct polytrifluoromethylation of solid perylene-3,4,9,10-tetracarboxylic dianhydride that produced a new family of (poly)perfluoroalkyl bay- and ortho-substituted PDIs with two different imide substituents. Direct hydrogen substitution with CN group led to the synthesis of a cyanated perfluoroalkyl PDI derivative for the first time. Absorption, steady-state and time-resolved emission, X-ray diffraction, electrochemical, and gas-phase electron affinity data allowed for systematic studies of substitution effects at bay, ortho, and imide positions in the new PDIs. Solid-state packing showed remarkable variations in the intermolecular interactions that are important for charge transport and photophysical properties. Moreover, analysis of the electrochemical data for 143 electron poor PDIs, including newly reported compounds, revealed some general trends and peculiar effects from substituting electron-withdrawing groups at all three positions.

  15. Module bay with directed flow

    Science.gov (United States)

    Torczynski, John R.

    2001-02-27

    A module bay requires less cleanroom airflow. A shaped gas inlet passage can allow cleanroom air into the module bay with flow velocity preferentially directed toward contaminant rich portions of a processing module in the module bay. Preferential gas flow direction can more efficiently purge contaminants from appropriate portions of the module bay, allowing a reduced cleanroom air flow rate for contaminant removal. A shelf extending from an air inlet slit in one wall of a module bay can direct air flowing therethrough toward contaminant-rich portions of the module bay, such as a junction between a lid and base of a processing module.

  16. 33 CFR 100.124 - Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York.

    Science.gov (United States)

    2010-07-01

    ... South Bay Cross Bay Swim, Great South Bay, New York. 100.124 Section 100.124 Navigation and Navigable... NAVIGABLE WATERS § 100.124 Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York... swimmer or safety craft on the swim event race course bounded by the following points: Starting Point...

  17. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors.

    Science.gov (United States)

    Si, Liang; Baier, Horst

    2015-07-08

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with "orange peel" surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments.

  18. The Chicxulub impact structure: What does the Yaxcopoil-1 drill core reveal?

    Science.gov (United States)

    Elbra, T.

    2013-05-01

    The Chicxulub impact structure, one of the largest impact structures on Earth, was formed 65 Ma by hypervelocity impact which led to the large mass-extinction at K-Pg boundary. This well preserved but buried structure has undergone numerous drillings and studies aimed to understand the formation mechanism, structure and age of the crater. The Yaxcopoil-1 (Yax-1) drill core, located in the southern sector of the Chicxulub crater, in the outer part of an annular trough, 62 km from the crater center, was drilled by ICDP in 2001-2002. Petrophysical, rock- and paleomagnetic studies of Yax-1 (Elbra and Pesonen, 2011) showed that physical properties characterize the various lithological units. Dependence on mineral composition rather than fabric was observed in pre-impact lithologies contrarily to the post-impact and impact rocks where the physical properties were dominated by porosity and reflected, in case of impactites, the impact formation mechanism with its numerous features resulting from melting, brecciation and fracturing. Furthermore, while the pre- and post-impact lithologies in Yax-1 are mostly dia- or paramagnetic, the impactite units indicated enhanced magnetizations and the presence of ferromagnetic, probably hydrothermally deposited magnetite and pyrrhotite. The sharp contrast of the impactites to the target and to post-impact lithologies allowed establishing the contact (especially the K-Pg boundary) between. The anisotropy, shape and orientation of the magnetic fraction illustrated the fabric randomization and showed the influence of impact-related redeposition and hydrothermal activity. The paleomagnetic data suggested that the Chicxulub impact occurred during the reverse polarity geomagnetic chron 29R, which is in agreement with the isotopic dates of the Chicxulub impact as well as with expected K-Pg boundary polarity. Reference Elbra, T. and Pesonen, L.J., 2011. Physical properties of the Yaxcopoil-1 deep drill core, Chicxulub impact structure, Mexico

  19. Volcanisme, activité anthropique et circulation des masses océaniques : leur influence respective sur la distribution des populations d'ostracodes dans la baie de Kagoshima (île de Kyushu, Japon)Impact of volcanism, human activities, and water mass circulation on the distribution of ostracod populations in Kagoshima Bay (Kyushu Island, southern Japan)

    Science.gov (United States)

    Bodergat, Anne-Marie; Oki, Kimihiko; Ishizaki, Kunihiro; Rio, Michel

    2002-11-01

    The distribution of ostracod populations in Kagoshima Bay (Japan) is analysed with reference to different environmental parameters. The bay is an area of volcanic activity of Sakurajima volcano under the influence of the Kuroshio Current. Most of the Head environment is occupied by an acidic water mass. Numbers of individual and species decrease from the Mouth of the bay towards the Basin and Head environments. In this latter, acidic water mass has a drastic effect on ostracod populations, whereas volcanic ashes and domestic inputs are not hostile. Ostracod distribution is influenced by the quality and structure of water masses. To cite this article: A.-M. Bodergat et al., C. R. Geoscience 334 (2002) 1053-1059.

  20. Multi-year investigations of aerosols from an island station, Port Blair, in the Bay of Bengal: climatology and source impacts

    Science.gov (United States)

    Naseema Beegum, S.; Krishna Moorthy, K.; Gogoi, Mukunda M.; Babu, S. Suresh; Pandey, S. K.

    2012-08-01

    Long-term measurements of spectral aerosol optical depth (AOD) using multi-wavelength solar radiometer (MWR) for a period of seven years (from 2002 to 2008) from the island location, Port Blair (11.63° N, 92.7° E, PBR) in the Bay of Bengal (BoB), along with the concurrent measurements of the size distribution of near-surface aerosols, have been analyzed to delineate the climatological features of aerosols over eastern BoB. In order to identity the contribution of different aerosol types from distinct sources, concentration weighted trajectory (CWT) analysis has been employed. Climatologically, AODs increase from January to reach peak value of ~0.4 (at 500 nm) in March, followed by a weak decrease towards May. Over this general pattern, significant modulations of intra-seasonal time scales, caused by the changes in the relative strength of distinctively different sources, are noticed. The derivative (α') of the Angstrom wavelength exponent α in the wavelength domain, along with CWT analysis, are used to delineate the different important aerosol types that influence this remote island. Corresponding changes in the aerosol size distributions are inferred from the numerical inversion of the spectral AODs as well from (surface) measurements. The analyses revealed that advection plays a major role in modifying the aerosol properties over the remote island location, the potential sources contributing to the accumulation mode (coarse mode) aerosols over eastern BoB being the East Asia and South China regions (Indian mainland and the oceanic regions).

  1. Market power versus capital structure determinants: Do they impact leverage?

    Directory of Open Access Journals (Sweden)

    Agha Jahanzeb

    2015-12-01

    Full Text Available The purpose of this study is to investigate the association between market power and capital structure. This study will further provide a logical explanation towards the factors affecting capital structure. This study analysed 176 non-financial Pakistani companies listed on Karachi Stock Exchange over the period of 2003–2012. Capital structure has been tried to investigate with a different perspective by investigating its association with market power. It has been seen that there is a significant and positive relation between market power and capital structure. Size and liquidity remained significantly negative with capital structure, whereas profitability and dividend payout remained significantly positive with capital structure. To the best of authors’ knowledge, this is the first study that investigates the relationship between market power and capital structure in any developing economy by employing the data of non-financial Pakistani firms.

  2. 湛江湾电厂脱硫酸性废水排放对海洋叶绿素影响研究%The impact of the acidic effluent discharge from power plant on chlorophyll in Zhanjiang Bay

    Institute of Scientific and Technical Information of China (English)

    梁春林; 陈春亮; 孙省利; 张际标

    2014-01-01

    To investigate the effect of the acidic effluent from power plants draining into Zhanjiang Bay on the sea water pH changes and chlorophyll concentration. The mode of chlorophyll concentration to pH was established through field survey and laboratory simulation. Then, ECOMSED and water quality model were applied to predict the change rate and influenced scope of chlorophyll in Zhanjiang Bay. The experimental results showed that the chlorophyll concentration was significantly impacted by pH. The pH range of 7.5 to 8.5 is the optimal pH range for chlorophyll synthesis. The responsing mode of chlorophyll concentration to pH may be defined by a quadratic equation. The predicted results showed that the extreme area of chlorophyll concentration decreased 1.0%is 16.10 km2 during the spring and neap tide, when the acidic effluent from power plants drained into Zhanjiang Bay. But, the extreme area of chlorophyll concentration increased 1.0%is 2.18 km2 during the spring and neap tide. The per-centages of extreme area were 8.47%and 1.15%of Zhanjiang Bay, respectively.%为了清晰理解湛江湾内某电厂脱硫酸性废水排放引起海水pH的变化分布及其对叶绿素浓度的影响,在野外调查及实验室模拟的基础上建立叶绿素浓度对pH的响应模式,并基于ECOMSED海洋模式和水质模型预测湛江湾叶绿素浓度的变化率和影响范围。实验室模拟结果表明,叶绿素浓度受pH影响较大,比较适宜叶绿素合成的pH区间为7.5~8.5,叶绿素浓度对pH的响应模式可以用二次多项式函数表达。预测结果表明,电厂脱硫酸性废水排放导致湛江湾叶绿素浓度下降超过1.0%的全潮极端影响面积为16.10 km2,而引起叶绿素浓度增加超过1.0%的全潮极端影响面积为2.18 km2,分别占湛江湾海域面积的8.47%和1.15%。

  3. The Coast Guard and Customs Forces of Algeciras Bay

    Directory of Open Access Journals (Sweden)

    Manuel Quero Oliván

    2016-09-01

    Full Text Available The article gives a brief history of the Coast Guard and Customs Enforcement in Algeciras bay. Showing the difficulties faced by the Spanish customs, given the list of the ship's structure.

  4. Bay of Bengal Surface and Thermocline and the Arabian Sea

    Science.gov (United States)

    2014-09-30

    BoB) is affected by many contrasting water types. The strong monsoonal forcing induces a complex array of energetic meso-scale and sub-meso-scales...COMPLETED Argo data has been assembled to build a climatology (2003-2014) of the thermohaline stratification within the Bay of Bengal. This product ... IOD , hold promise as a simple, yet effective means of predicting an IOD event’. 10 IMPACT/APPLICATIONS The Bay of Bengal complex, energetic

  5. Three-dimensional water impact at normal incidence to a blunt structure

    Science.gov (United States)

    Chatjigeorgiou, I. K.; Cooker, M. J.; Korobkin, A. A.

    2016-08-01

    The three-dimensional water impact onto a blunt structure with a spreading rectangular contact region is studied. The structure is mounted on a flat rigid plane with the impermeable curved surface of the structure perpendicular to the plane. Before impact, the water region is a rectangular domain of finite thickness bounded from below by the rigid plane and above by the flat free surface. The front free surface of the water region is vertical, representing the front of an advancing steep wave. The water region is initially advancing towards the structure at a constant uniform speed. We are concerned with the slamming loads acting on the surface of the structure during the initial stage of water impact. Air, gravity and surface tension are neglected. The problem is analysed by using some ideas of pressure-impulse theory, but including the time-dependence of the wetted area of the structure. The flow caused by the impact is three-dimensional and incompressible. The distribution of the pressure-impulse (the time-integral of pressure) over the surface of the structure is analysed and compared with the distributions provided by strip theories. The total impulse exerted on the structure during the impact stage is evaluated and compared with numerical and experimental predictions. An example calculation is presented of water impact onto a vertical rigid cylinder. Three-dimensional effects on the slamming loads are the main concern in this study.

  6. Modelling hypervelocity impacts into aluminum structures based on LDEF data

    Science.gov (United States)

    Coombs, C. R.; Atkinson, D. R.; Watts, A. J.; Wagner, J. R.; Allbrooks, M. K.; Hennessy, C. J.

    1993-01-01

    Realizing and understanding the effects of the near-Earth space environment on a spacecraft during its mission lifetime is becoming more important with the regeneration of America's space program. Included among these potential effects are the following: erosion and surface degradation due to atomic oxygen impingement; ultraviolet exposure embrittlement; and delamination, pitting, cratering, and ring formation due to micrometeoroid and debris impacts. These effects may occur synergistically and may alter the spacecraft materials enough to modify the resultant crater, star crack, and/or perforation. This study concentrates on modelling the effects of micrometeoroid and debris hypervelocity impacts into aluminum materials (6061-T6). Space debris exists in all sizes, and has the possibility of growing into a potentially catastrophic problem, particularly since self-collisions between particles can rapidly escalate the number of small impactors. We have examined the morphologies of the Long Duration Exposure Facility (LDEF) impact craters and the relationship between the observed impact damage on LDEF versus the existing models for both the natural (micrometeoroid) and manmade (debris) environments in order to better define these environments.

  7. Droplet impact on superheated micro-structured surfaces

    NARCIS (Netherlands)

    Tran, A.T.; Staat, H.J.J.; Susarrey-Arce, A.; Foertsch, T.C.; Houselt, van A.; Gardeniers, J.G.E.; Prosperetti, A.; Lohse, D.; Sun, C.

    2013-01-01

    When a droplet impacts upon a surface heated above the liquid's boiling point, the droplet either comes into contact with the surface and boils immediately (contact boiling), or is supported by a developing vapor layer and bounces back (film boiling, or Leidenfrost state). We study the transition be

  8. Towards reliable simulations of ballistic impact on concrete structures

    NARCIS (Netherlands)

    Khoe, Y.S.; Tyler Street, M.D.; Maravalalu Suresh,, R.S.; Weerheijm, J.

    2013-01-01

    Protection against weapon effects like ballistic impacts, fragmenting shells and explosions is the core business of the Explosions, Ballistics and Protection department of TNO (The Netherlands). Experimental and numerical research is performed to gain and maintain the knowledge to support the Dutch

  9. Multi-year investigations of aerosols from an island station, Port Blair, in the Bay of Bengal. Climatology and source impacts

    Energy Technology Data Exchange (ETDEWEB)

    Beegum, S. Naseema [CSIR, New Delhi (India). National Physical Lab.; Moorthy, K. Krishna; Gogoi, Mukunda M.; Babu, S. Suresh [VSSC, Thiruvananthapuram (India). Space Physics Lab.; Pandey, S.K. [ISTRAC ground station, Dolly Gunj, Port Blair (India)

    2012-11-01

    Long-term measurements of spectral aerosol optical depth (AOD) using multi-wavelength solar radiometer (MWR) for a period of seven years (from 2002 to 2008) from the island location, Port Blair (11.63 N, 92.7 E, PBR) in the Bay of Bengal (BoB), along with the concurrent measurements of the size distribution of near-surface aerosols, have been analyzed to delineate the climatological features of aerosols over eastern BoB. In order to identity the contribution of different aerosol types from distinct sources, concentration weighted trajectory (CWT) analysis has been employed. Climatologically, AODs increase from January to reach peak value of {proportional_to}0.4 (at 500 nm) in March, followed by a weak decrease towards May. Over this general pattern, significant modulations of intra-seasonal time scales, caused by the changes in the relative strength of distinctively different sources, are noticed. The derivative ({alpha}{sup '}) of the Angstrom wavelength exponent {alpha} in the wavelength domain, along with CWT analysis, are used to delineate the different important aerosol types that influence this remote island. Corresponding changes in the aerosol size distributions are inferred from the numerical inversion of the spectral AODs as well from (surface) measurements. The analyses revealed that advection plays a major role in modifying the aerosol properties over the remote island location, the potential sources contributing to the accumulation mode (coarse mode) aerosols over eastern BoB being the East Asia and South China regions (Indian mainland and the oceanic regions). (orig.)

  10. Rising sea level, temperature, and precipitation impact plant and ecosystem responses to elevated CO2 on a Chesapeake Bay wetland: review of a 28-year study.

    Science.gov (United States)

    Drake, Bert G

    2014-11-01

    An ongoing field study of the effects of elevated atmospheric CO2 on a brackish wetland on Chesapeake Bay, started in 1987, is unique as the longest continually running investigation of the effects of elevated CO2 on an ecosystem. Since the beginning of the study, atmospheric CO2 increased 18%, sea level rose 20 cm, and growing season temperature varied with approximately the same range as predicted for global warming in the 21st century. This review looks back at this study for clues about how the effects of rising sea level, temperature, and precipitation interact with high atmospheric CO2 to alter the physiology of C3 and C4 photosynthetic species, carbon assimilation, evapotranspiration, plant and ecosystem nitrogen, and distribution of plant communities in this brackish wetland. Rising sea level caused a shift to higher elevations in the Scirpus olneyi C3 populations on the wetland, displacing the Spartina patens C4 populations. Elevated CO2 stimulated carbon assimilation in the Scirpus C3 species measured by increased shoot and root density and biomass, net ecosystem production, dissolved organic and inorganic carbon, and methane production. But elevated CO2 also decreased biomass of the grass, S. patens C4. The elevated CO2 treatment reduced tissue nitrogen concentration in shoots, roots, and total canopy nitrogen, which was associated with reduced ecosystem respiration. Net ecosystem production was mediated by precipitation through soil salinity: high salinity reduced the CO2 effect on net ecosystem production, which was zero in years of severe drought. The elevated CO2 stimulation of shoot density in the Scirpus C3 species was sustained throughout the 28 years of the study. Results from this study suggest that rising CO2 can add substantial amounts of carbon to ecosystems through stimulation of carbon assimilation, increased root exudates to supply nitrogen fixation, reduced dark respiration, and improved water and nitrogen use efficiency.

  11. Nutrients, heavy metals and phthalate acid esters in solar greenhouse soils in Round-Bohai Bay-Region, China: impacts of cultivation year and biogeography.

    Science.gov (United States)

    Chen, Zhiqun; Tian, Tian; Gao, Lihong; Tian, Yongqiang

    2016-07-01

    Solar greenhouse is a common facility type used for horticultural crop production in China. However, most solar greenhouse fields have been degraded due to continuous cropping and excessive fertilizer use. Therefore, we investigated solar greenhouse soils covering a wide range of cultivation years and environmental conditions in Round-Bohai Bay-Region to test the effects of cultivation year and biogeography on nutrients, heavy metals, and phthalate acid esters (PAEs). In general, soil pH decreased while soil electrical conductivity (EC), organic matter (OM), total nitrogen (TN), NO3 (-)-N, NH4 (+)-N, mineral nitrogen (MN), Olsen-P, and NH4OAc-K contents increased as time of cultivation increased. However, this trend was influenced by sampling sites. Among sampling sites, Jiangsu showed a relatively low soil pH and high Olsen-P content, while Hebei showed a relatively high soil EC value, NO3 (-)-N, NH4 (+)-N, MN, and NH4OAc-K contents. Liaoning was characterized by relatively high soil OM and TN contents. The nutrient level indexes in evaluation of soil quality on Olsen-P and NH4OAc-K exceeded the standard seriously. The maximum values of the heavy metals Cd, Cu, and Zn were 4.87, 2.78, and 1.15 times higher than the threshold values, respectively. There was a rising trend on the heavy metal contents with the increasing cultivation years, and this trend was significantly influenced by sampling sites. Both Cu and Zn had relative high heavy metal indexes in evaluation of soil pollution. The PAEs were not detected in almost all sampling soils. Overall, the excessive fertilizer application was an important cause of nutrient accumulation and heavy metal pollution, resulting in soil degradation in solar greenhouses.

  12. What a difference a bay makes: natural variation in dietary resources mediates growth in a recently settled herbivorous fish

    Science.gov (United States)

    Priest, Mark A.; Halford, Andrew R.; Clements, Kendall D.; Douglas, Emily; Abellana, Sheena L.; McIlwain, Jennifer L.

    2016-12-01

    Processes acting during the early stages of coral reef fish life cycles have a disproportionate influence on their adult abundance and community structure. Higher growth rates, for example, confer a major fitness advantage in larval and juvenile fishes, with larger fish undergoing significantly less mortality. The role of dietary resources in the size-structuring process has not been well validated, especially at the early post-settlement phase, where competition and predation are seen as preeminent drivers of juvenile fish assemblage structure. Here, we report on a size differential of 10-20% between recently settled Siganus spinus rabbitfish recruits from different bays around the Pacific island of Guam. This difference was maintained across multiple recruitment events within and between years. After confirming the validity of our observations through otolith increment analysis, subsequent investigation into the drivers of this variation revealed significant differences in the structure of algal assemblages between bays, congruent with the observed differences in size of the recently settled fish. Gut analyses showed a greater presence of algal types with higher levels of nitrogen and phosphorus in the stomachs of fish from Tanguisson, the bay with the largest observed recruits. To ensure this mechanism was one of causation and not correlation, we conducted a fully factorial experiment in which S. spinus recruits sampled from different bays were reared on all combinations of algal diets representative of the different bays. Recruits on the `Tanguisson' diet grew faster than recruits on other diets, regardless of their origin. We propose that the greater availability of high-quality dietary resources at this location is likely conferring benefits that impact on the population-level dynamics of this species. The spatial and temporal extent of this process clearly implicates food as a limiting resource, capable of mediating fish population dynamics at multiple

  13. Impact factors of fractal analysis of porous structure

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Characterization of pore structure is one of the key problems for fabrication and application research on porous materials. But, complexity of pore structure makes it difficult to characterize pore structure by Euclidean geometry and traditional experimental methods. Fractal theory has been proved effective to characterize the complex pore structure. The box dimension method based on fractal theory was applied to characterizing the pore structure of fiber porous materials by analyzing the electronic scanning microscope (SEM) images of the porous materials in this paper. The influences of image resolution, threshold value, and image magnification on fractal analysis were investigated. The results indicate that such factors greatly affect fractal analysis process and results. The appropriate magnification threshold and fractal analysis are necessary for fractal analysis.

  14. Thatcher Bay, Washington, Nearshore Restoration Assessment

    Science.gov (United States)

    Breems, Joel; Wyllie-Echeverria, Sandy; Grossman, Eric E.; Elliott, Joel

    2009-01-01

    The San Juan Archipelago, located at the confluence of the Puget Sound, the Straits of Juan de Fuca in Washington State, and the Straits of Georgia, British Columbia, Canada, provides essential nearshore habitat for diverse salmonid, forage fish, and bird populations. With 408 miles of coastline, the San Juan Islands provide a significant portion of the available nearshore habitat for the greater Puget Sound and are an essential part of the regional efforts to restore Puget Sound (Puget Sound Shared Strategy 2005). The nearshore areas of the San Juan Islands provide a critical link between the terrestrial and marine environments. For this reason the focus on restoration and conservation of nearshore habitat in the San Juan Islands is of paramount importance. Wood-waste was a common by-product of historical lumber-milling operations. To date, relatively little attention has been given to the impact of historical lumber-milling operations in the San Juan Archipelago. Thatcher Bay, on Blakely Island, located near the east edge of the archipelago, is presented here as a case study on the restoration potential for a wood-waste contaminated nearshore area. Case study components include (1) a brief discussion of the history of milling operations. (2) an estimate of the location and amount of the current distribution of wood-waste at the site, (3) a preliminary examination of the impacts of wood-waste on benthic flora and fauna at the site, and (4) the presentation of several restoration alternatives for the site. The history of milling activity in Thatcher Bay began in 1879 with the construction of a mill in the southeastern part of the bay. Milling activity continued for more than 60 years, until the mill closed in 1942. Currently, the primary evidence of the historical milling operations is the presence of approximately 5,000 yd3 of wood-waste contaminated sediments. The distribution and thickness of residual wood-waste at the site was determined by using sediment

  15. The Fermi's Bayes Theorem

    CERN Document Server

    D'Agostini, G

    2005-01-01

    It is curious to learn that Enrico Fermi knew how to base probabilistic inference on Bayes theorem, and that some influential notes on statistics for physicists stem from what the author calls elsewhere, but never in these notes, {\\it the Bayes Theorem of Fermi}. The fact is curious because the large majority of living physicists, educated in the second half of last century -- a kind of middle age in the statistical reasoning -- never heard of Bayes theorem during their studies, though they have been constantly using an intuitive reasoning quite Bayesian in spirit. This paper is based on recollections and notes by Jay Orear and on Gauss' ``Theoria motus corporum coelestium'', being the {\\it Princeps mathematicorum} remembered by Orear as source of Fermi's Bayesian reasoning.

  16. Fluid Structure Interaction Effects on Composites Under Low Velocity Impact

    Science.gov (United States)

    2012-06-01

    Interaction, FSI, low velocity impact, carbon fiber reinforced polymers, CFRP, carbon nanotubes, CNT, vacuum assisted resin transfer molding, VARTM . 16...Ethyl Ketone Peroxide MWCNT Multi-Walled Carbon Nanotube VARTM Vacuum-Assisted Resin Transfer Molding xiv THIS PAGE INTENTIONALLY LEFT BLANK...samples used in this research is known as vacuum assisted resin transfer molding ( VARTM ). VARTM is a very common method used in low pressure composite

  17. Impact of aging and material structure on CANDU plant performance

    Energy Technology Data Exchange (ETDEWEB)

    Nadeau, E.; Ballyk, J.; Ghalavand, N. [Candu Energy Inc., Mississauga, Ontario (Canada)

    2011-07-01

    In-service behaviour of pressure tubes is a key factor in the assessment of safety margins during plant operation. Pressure tube deformation (diametral expansion) affects fuel bundle dry out characteristics resulting in reduced margin to trip for some events. Pressure tube aging mechanisms also erode design margins on fuel channels or interfacing reactor components. The degradation mechanisms of interest are primarily deformation, loss of fracture resistance and hydrogen ingress. CANDU (CANada Deuterium Uranium, a registered trademark of the Atomic Energy of Canada Limited used under exclusive licence by Candu Energy Inc.) owners and operators need to maximize plant capacity factor and meet or exceed the reactor design life targets while maintaining safety margins. The degradation of pressure tube material and geometry are characterized through a program of inspection, material surveillance and assessment and need to be managed to optimize plant performance. Candu is improving pressure tubes installed in new build and life extension projects. Improvements include changes designed to reduce or mitigate the impact of pressure tube elongation and diametral expansion rates, improvement of pressure tube fracture properties, and reduction of the implications of hydrogen ingress. In addition, Candu provides an extensive array of engineering services designed to assess the condition of pressure tubes and address the impact of pressure tube degradation on safety margins and plant performance. These services include periodic and in-service inspection and material surveillance of pressure tubes and deterministic and probabilistic assessment of pressure tube fitness for service to applicable standards. Activities designed to mitigate the impact of pressure tube deformation on safety margins include steam generator cleaning, which improves trip margins, and trip design assessment to optimize reactor trip set points restoring safety and operating margins. This paper provides an

  18. Effect of grain structure on Charpy impact behavior of copper

    Science.gov (United States)

    Liang, Ningning; Zhao, Yonghao; Wang, Jingtao; Zhu, Yuntian

    2017-01-01

    Nanostructured (NS) and ultrafine-grained (UFG) materials have high strength and relatively low ductility. Their toughness has not been comprehensively investigated. Here we report the Charpy impact behavior and the corresponding microstructural evolutions in UFG Cu with equi-axed and elongated grains which were prepared by equal channel angular pressing (ECAP) for 2 and 16 passes at room temperature. It is found that their impact toughness (48 J/cm2) is almost comparable to that of coarse grained (CG) Cu: 55 J/cm2. The high strain rate during the Charpy impact was found to enhance the strain hardening capability of the UFG Cu due to the suppression of dynamic dislocation recovery. The crack in the CG Cu was blunted by dislocation-slip mediated plastic deformation, while the cracks in the UFG Cu were formed at grain boundaries and triple junctions due to their limited plasticity. Near the crack surfaces the elongated grains in ECAP-2 sample were refined by recrystallization, while equi-axed grains in the ECAP-16 sample grew larger. PMID:28303950

  19. X-Ray Diffraction Powder Patterns and Thin Section Observations from the Sierra Madera Impact Structure

    Science.gov (United States)

    Huson, S. A.; Foit, F. F.; Watkinson, A. J.; Pope, M. C.

    2006-03-01

    X-Ray powder diffraction analysis and thin section observations of carbonate and siliciclastic samples from the Sierra Madera impact structure indicate moderate shock pressures (8 to 30 GPa) were generated during the formation of this crater.

  20. Vulnerability Assessment for a Complex Structure Using Vibration Response Induced by Impact Load

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeongwon; Park, Junhong [Hanyang University, Seoul (Korea, Republic of); Koo, Man Hoi [Agency for Defense Development, Daejeon (Korea, Republic of)

    2014-10-15

    This work presents a vulnerability assessment procedure for a complex structure using vibration characteristics. The structural behavior of a three-dimensional framed structure subjected to impact forces was predicted using the spectral element method. The Timoshenko beam function was applied to simulate the impact wave propagations induced by a high-velocity projectile at relatively high frequencies. The interactions at the joints were analyzed for both flexural and longitudinal wave propagations. Simulations of the impact energy transfer through the entire structure were performed using the transient displacement and acceleration responses obtained from the frequency analysis. The kill probabilities of the crucial components for an operating system were calculated as a function of the predicted acceleration amplitudes according to the acceptable vibration levels. Following the proposed vulnerability assessment procedure, the vulnerable positions of a three-dimensional combat vehicle with high possibilities of damage generation of components by impact loading were identified from the estimated vibration responses.

  1. THE ECOLOGICAL STRUCTURE MACROFAULING COMMUNITY OF THE EASTERN SHORE OF THE POMERANIAN BAY (SOUTHERN BALTIC SEA IN 2008 ON THE ANTHROPOGENIC SUBSTRATES

    Directory of Open Access Journals (Sweden)

    Beata Rosińska

    2014-10-01

    Full Text Available In 2008, observations carried out on groups of biofauling organisms Pomeranian Bay. Appointed position in Międzyzdroje, Kołobrzeg and Niechorze. Samples of organisms were collected from the pillars of the pier, wooden spurs and conctrte starblocks as part of the breakwaters in each village. The biological material has been collected in the spring (11 May 2008, summer (July 27, 2008 and early autumn (September 14, 2008. There have been qualitative and quantitative analysis of any invertebrate organisms collected.

  2. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    Science.gov (United States)

    Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong

    2012-01-01

    The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…

  3. Environmental and sanitary conditions of Guanabara Bay, Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Giovana De Oliveira Fistarol

    2015-11-01

    Full Text Available Guanabara Bay is the second largest bay in the coast of Brazil, with an area of 384 km2. In its surroundings live circa 16 million inhabitants, out of which 6 million live in Rio de Janeiro city, one of the largest cities of the country, and the host of the 2016 Olympic Games. Anthropogenic interference in Guanabara Bay area started early in the XVI century, but environmental impacts escalated from 1930, when this region underwent an industrialization process. Herein we present an overview of the current environmental and sanitary conditions of Guanabara Bay, a consequence of all these decades of impacts. We will focus on microbial communities, how they may affect higher trophic levels of the aquatic community and also human health. The anthropogenic impacts in the bay are flagged by heavy eutrophication and by the emergence of pathogenic microorganisms that are either carried by domestic and/or hospital waste (e.g. virus, KPC-producing bacteria, and fecal coliforms, or that proliferate in such conditions (e.g. vibrios. Antibiotic resistance genes are commonly found in metagenomes of Guanabara Bay planktonic microorganisms. Furthermore, eutrophication results in recurrent algal blooms, with signs of a shift towards flagellated, mixotrophic groups, including several potentially harmful species. A recent large-scale fish kill episode, and a long trend decrease in fish stocks also reflects the bay’s degraded water quality. Although pollution of Guanabara Bay is not a recent problem, the hosting of the 2016 Olympic Games propelled the government to launch a series plans to restore the bay’s water quality. If all plans are fully implemented, the restoration of Guanabara Bay and its shores may be one of the best legacies of the Olympic Games in Rio de Janeiro.

  4. Environmental and Sanitary Conditions of Guanabara Bay, Rio de Janeiro

    Science.gov (United States)

    Fistarol, Giovana O.; Coutinho, Felipe H.; Moreira, Ana Paula B.; Venas, Tainá; Cánovas, Alba; de Paula, Sérgio E. M.; Coutinho, Ricardo; de Moura, Rodrigo L.; Valentin, Jean Louis; Tenenbaum, Denise R.; Paranhos, Rodolfo; do Valle, Rogério de A. B.; Vicente, Ana Carolina P.; Amado Filho, Gilberto M.; Pereira, Renato Crespo; Kruger, Ricardo; Rezende, Carlos E.; Thompson, Cristiane C.; Salomon, Paulo S.; Thompson, Fabiano L.

    2015-01-01

    Guanabara Bay is the second largest bay in the coast of Brazil, with an area of 384 km2. In its surroundings live circa 16 million inhabitants, out of which 6 million live in Rio de Janeiro city, one of the largest cities of the country, and the host of the 2016 Olympic Games. Anthropogenic interference in Guanabara Bay area started early in the XVI century, but environmental impacts escalated from 1930, when this region underwent an industrialization process. Herein we present an overview of the current environmental and sanitary conditions of Guanabara Bay, a consequence of all these decades of impacts. We will focus on microbial communities, how they may affect higher trophic levels of the aquatic community and also human health. The anthropogenic impacts in the bay are flagged by heavy eutrophication and by the emergence of pathogenic microorganisms that are either carried by domestic and/or hospital waste (e.g., virus, KPC-producing bacteria, and fecal coliforms), or that proliferate in such conditions (e.g., vibrios). Antibiotic resistance genes are commonly found in metagenomes of Guanabara Bay planktonic microorganisms. Furthermore, eutrophication results in recurrent algal blooms, with signs of a shift toward flagellated, mixotrophic groups, including several potentially harmful species. A recent large-scale fish kill episode, and a long trend decrease in fish stocks also reflects the bay’s degraded water quality. Although pollution of Guanabara Bay is not a recent problem, the hosting of the 2016 Olympic Games propelled the government to launch a series of plans to restore the bay’s water quality. If all plans are fully implemented, the restoration of Guanabara Bay and its shores may be one of the best legacies of the Olympic Games in Rio de Janeiro. PMID:26635734

  5. Simulation of the Crashing of Sandwich Structures under Impact Loads by Movable Cellular Automata

    Institute of Scientific and Technical Information of China (English)

    HUANG De-wu; HUANG Hai; SONG Yi; A I Dmitriev; E V Shilko; S G Psakhie

    2005-01-01

    Movable cellular automata (MCA) method is applied in the analysis of dynamic characters of ceramic armor composite structures under impact loading. As a new approach, MCA is different from the traditional numerical methods such as the finite element method and boundary element method. Based on the theory of particle mechanics, MCA is applied as a powerful tool in solving specific structural analysis of materials loss and penetrating damages. In this paper the method is used to study responses of multi-layered ceramic plates as a base of armor structures under impact loading, thus assisting further investigations in the crashing process and to improve ceramic armor structures.

  6. Optimization of large amorphous silicon and silica structures for molecular dynamics simulations of energetic impacts

    Energy Technology Data Exchange (ETDEWEB)

    Samela, Juha, E-mail: juha.samela@helsinki.fi [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FI-00014 University of Helsinki (Finland); Norris, Scott A. [Southern Methodist University, Dallas, TX 75205 (United States); Nordlund, Kai [Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FI-00014 University of Helsinki (Finland); Aziz, Michael J. [School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138 (United States)

    2011-07-15

    A practical method to create optimized amorphous silicon and silica structures for molecular dynamics simulations is developed and tested. The method is based on the Wooten, Winer, and Weaire algorithm and combination of small optimized blocks to larger structures. The method makes possible to perform simulations of either very large cluster hypervelocity impacts on amorphous targets or small displacements induced by low energy ion impacts in silicon.

  7. The Impact of Changes of the Internal Agricultural Structure in Sichuan Province on Farmers’ Income

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    After introducing the status quo of farmers’ net income and gross output value of agriculture of Sichuan Province,and the changes of agricultural output structure,the regression analysis was conducted on the impact of the changes in agricultural structure on the farmers’ net income per capita on the strengthen of the data from Sichuan statistical yearbook and by the way of econometrics.The multiple linear regression analysis was conducted on the impact the changes in crop farming on farmers’ net income by using logarithmic demand model.The results show that the agricultural structure has transformed from the dominant crop farming to the all-around developmental trend covering the dominant industry,animal husbandry and forestry,fishery and the other industries;the animal husbandry has greatest impact on famers’ income per capita and the impact of crop farming is slightly weaker than animal husbandry;the crop farming and animal husbandry develop fairly rapid simultaneously and the two all have great impact in farmers’ income;among animal husbandry,the meat and eggs have relatively great impact on farmers’ income,while in crop farming,grain plays the dominant role in affecting farmers’ income,followed by cash crop.Hence,the relevant countermeasures applied to increase farmers’ income are put forward in terms of optimizing the internal structure of agriculture,adjusting the internal structure of crop farming,adjusting the internal structure of animal husbandry and strengthening the support of farmers.

  8. Coffee melanoidins: structures, mechanisms of formation and potential health impacts.

    Science.gov (United States)

    Moreira, Ana S P; Nunes, Fernando M; Domingues, M Rosário; Coimbra, Manuel A

    2012-09-01

    During the roasting process, coffee bean components undergo structural changes leading to the formation of melanoidins, which are defined as high molecular weight nitrogenous and brown-colored compounds. As coffee brew is one of the main sources of melanoidins in the human diet, their health implications are of great interest. In fact, several biological activities, such as antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative activities, have been attributed to coffee melanoidins. To understand the potential of coffee melanoidin health benefits, it is essential to know their chemical structures. The studies undertaken to date dealing with the structural characterization of coffee melanoidins have shown that polysaccharides, proteins, and chlorogenic acids are involved in coffee melanoidin formation. However, exact structures of coffee melanoidins and mechanisms involved in their formation are far to be elucidated. This paper systematizes the available information and provides a critical overview of the knowledge obtained so far about the structure of coffee melanoidins, mechanisms of their formation, and their potential health implications.

  9. Food-web structure of seagrass communities across different spatial scales and human impacts.

    Science.gov (United States)

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  10. Deep Borehole Instrumentation Along San Francisco Bay Bridges - 2000

    Energy Technology Data Exchange (ETDEWEB)

    Hutchings, L.; Kasameyer, P.; Turpin, C.; Long, L.; Hollfelder, J.; McEvilly, T.; Clymer, R.; Uhrhammer, R.

    2000-03-01

    This is a progress report on the Bay Bridges downhole network. Between 2 and 8 instruments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges in San Francisco Bay, California. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty-one sensor packages at fifteen sites. The downhole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 731 accelerometers, and is capable of recording a micro g from local M = 1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes. Preliminary results on phasing across the Bay Bridge, up and down hole wave amplification at Yerba Buena Island, and sensor orientation analysis are presented. Events recorded and located during 1999 are presented. Also, a senior thesis on the deep structure of the San Francisco Bay beneath the Bay Bridge is presented as an addendum.

  11. Impacts of Hazardous Air Pollutants Emitted from Phosphate Fertilizer Production Plants on their Ambient Concentration Levels in the Tampa Bay Area

    Science.gov (United States)

    The concentrations and distribution of Hazardous Air Pollutants (HAPs) metals emitted from four phosphate fertilizer plants in Central Florida, as well as their environmental and health impacts, were assessed. The dominant HAP metals emitted from the stacks of these plants were M...

  12. Modeling of fracture of protective concrete structures under impact loads

    Energy Technology Data Exchange (ETDEWEB)

    Radchenko, P. A., E-mail: radchenko@live.ru; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation)

    2015-10-27

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  13. National customer satisfaction indices: The impact of market structure

    DEFF Research Database (Denmark)

    Eskildsen, Jacob Kjær; Kristensen, Kai

    The popularity of customer satisfaction measurements has grown considerably over the last few years but we know very little about how the structure of the individual markets with respect to the transparency of products and services as well as consumer preferences affects customer satisfaction. Here...... a total of 14540 customers have evaluated their preferred supplier with respect to banking, property insurance, supermarkets and mobile telecom. The analysis shows that market structure has a profound effect on customer satisfaction measurements and that this effect differs from industry to industry....... The paper concludes with an evaluation of the implications of the findings in relation to the use of results from customer satisfaction studies....

  14. Correlation and assessment of structural airplane crash data with flight parameters at impact

    Science.gov (United States)

    Carden, H. D.

    1982-01-01

    Crash deceleration pulse data from a crash dynamics program on general aviation airplanes and from transport crash data were analyzed. Structural airplane crash data and flight parameters at impact were correlated. Uncoupled equations for the normal and longitudinal floor impulses in the cabin area of the airplane were derived, and analytical expressions for structural crushing during impact and horizontal slide out were also determined. Agreement was found between experimental and analytical data for general aviation and transport airplanes over a relatively wide range of impact parameter. Two possible applications of the impulse data are presented: a postcrash evaluation of crash test parameters and an assumed crash scenario.

  15. The Karakul depression in Pamirs: The first impact structure in Central Asia

    Science.gov (United States)

    Gurov, E. P.; Gurova, H. P.; Rakitskaya, R. B.; Yamnichenko, A. YU.

    1993-01-01

    The Karakul depression was picked out as the possible impact structure by the study of space images of Tadjikistan. Its striking similarity with some complex impact craters such as Dellen and Gosses Bluff is evident. Our investigations of the Karakul depression in 1987 and 1989-1991 years allowed to determine it as the impact crater with the central uplift. The target of the crater is presented by slightly metamorphosed sedimentary rocks of Paleozoic, intensively folded and intruded with granites during the Gercynian orogeny. The modern structure of north-eastern Pamirs was formed by Alpinian orogeny; the raise of the area in Neogene was about 4000-7000 m.

  16. The Rock Elm meteorite impact structure, Wisconsin: Geology and shock-metamorphic effects in quartz

    Science.gov (United States)

    French, B.M.; Cordua, W.S.; Plescia, J.B.

    2004-01-01

    The Rock Elm structure in southwest Wisconsin is an anomalous circular area of highly deformed rocks, ???6.5 km in diameter, located in a region of virtually horizontal undeformed sedimentary rocks. Shock-produced planar microstructures (PMs) have been identified in quartz grains in several lithologies associated with the structure: sandstones, quartzite pebbles, and breccia. Two distinct types of PMs are present: P1 features, which appear identical to planar fractures (PFs or cleavage), and P2 features, which are interpreted as possible incipient planar deformation features (PDFs). The latter are uniquely produced by the shock waves associated with meteorite impact events. Both types of PMs are oriented parallel to specific crystallographic planes in the quartz, most commonly to c(0001), ??112??2, and r/z101??1. The association of unusual, structurally deformed strata with distinct shock-produced microdeformation features in their quartz-bearing rocks establishes Rock Elm as a meteorite impact structure and supports the view that the presence of multiple parallel cleavages in quartz may be used independently as a criterion for meteorite impact. Preliminary paleontological studies indicate a minimum age of Middle Ordovician for the Rock Elm structure. A similar age estimate (450-400 Ma) is obtained independently by combining the results of studies of the general morphology of complex impact structures with estimated rates of sedimentation for the region. Such methods may be applicable to dating other old and deeply eroded impact structures formed in sedimentary target rocks.

  17. Research of hail impact on aircraft wheel door with lattice hybrid structure

    Science.gov (United States)

    Li, Shengze; Jin, Feng; Zhang, Weihua; Meng, Xuanzhu

    2016-09-01

    Aimed at a long lasting issue of hail impact on aircraft structures and aviation safety due to its high speed, the resistance performance of hail impact on the wheel door of aircraft with lattice hybrid structure is investigated. The proper anti-hail structure can be designed both efficiency and precision based on this work. The dynamic responses of 8 different sandwich plates in diverse impact speed are measured. Smoothed Particle Hydrodynamic (SPH) method is introduced to mimic the speciality of solid-liquid mixture trait of hailstone during the impact process. The deformation and damage degree of upper and lower panel of sandwich plate are analysed. The application range and failure mode for the relevant structure, as well as the energy absorbing ratio between lattice structure and aluminium foam are summarized. Results show that the tetrahedral sandwich plate with aluminium foam core is confirmed the best for absorbing energy. Furthermore, the high absorption characteristics of foam material enhance the capability of the impact resistance for the composition with lattice structure without increasing the structure surface density. The results of study are of worth to provide a reliable basis for reduced weight aircraft wheel door.

  18. CHARACTERISTICS OF STRUCTURE OF IMPACT COPOLYMERS OF POLYPROPYLENE WITH LOW ETHYLENE CONTENTS

    Institute of Scientific and Technical Information of China (English)

    MA Dezhu; LI Xiqiang; ZHANG Ruiyun; HONG Kunlun; LUO Xiaolie

    1994-01-01

    In the present work, the structure and impact properties of copolymers of polypropylene with low ethylene contents have been investigated. Based on the results of 13C-NMR, FTIR,WAXD, DSC, PLM and SEM, the relationship between impact properties and morphology of the copolymers has been discussed. The high impact properties of copolymer ICP2 may attribute to the relatively higher ethylene content and homogeneous ethylene unit distribution. The size and its distribution of spherulite in the copolymers and cycloid cavities dispersed in polypropylene continue phase may also be two important factors which affect the impact properties of these materials.

  19. Impact of Information Technology Governance Structures on Strategic Alignment

    Science.gov (United States)

    Gordon, Fitzroy R.

    2013-01-01

    This dissertation is a study of the relationship between Information Technology (IT) strategic alignment and IT governance structure within the organization. This dissertation replicates Asante (2010) among a different population where the prior results continue to hold, the non-experimental approach explored two research questions but include two…

  20. The Impact of Structural Adjustment on Training Needs.

    Science.gov (United States)

    Lucas, Robert E. B.

    1994-01-01

    During structural adjustment, training/retraining for unemployed persons is often poorly conceived. One reason is the lack of reliable ways to predict future skill requirements. Retraining should be kept fairly general to enable a wide range of potential jobs. (SK)

  1. Impacts of chemical gradients on microbial community structure

    DEFF Research Database (Denmark)

    Chen, Jianwei; Hanke, Anna; Tegetmeyer, Halina E

    2017-01-01

    Succession of redox processes is sometimes assumed to define a basic microbial community structure for ecosystems with oxygen gradients. In this paradigm, aerobic respiration, denitrification, fermentation and sulfate reduction proceed in a thermodynamically determined order, known as the 'redox ...... Journal advance online publication, 17 January 2017; doi:10.1038/ismej.2016.175....

  2. Impact of Structured Movement Time on Preschoolers' Physical Activity Engagement

    Science.gov (United States)

    Palmer, Kara K.; Matsuyama, Abigail L.; Robinson, Leah E.

    2017-01-01

    Preschool-aged children are not meeting national physical activity recommendations. This study compares preschoolers' physical activity engagement during two different physical activity opportunities: outdoor free play or a structured movement session. Eighty-seven children served as participants: 40 children participated in outdoor free play and…

  3. A model for the geomorphology of the Carolina Bays

    Science.gov (United States)

    Zamora, Antonio

    2017-04-01

    Geometrical analysis of the Carolina Bays using Google Earth in combination with LiDAR data makes it possible to postulate that the bays formed as the result of impacts, rather than from eolian and lacustrine processes. The Carolina Bays are elliptical conic sections with width-to-length ratios averaging 0.58 that are radially oriented toward the Great Lakes region. The radial distribution of ejecta is one characteristic of impacts, and the width-to-length ratios of the ellipses correspond to cones inclined at approximately 35°, which is consistent with ballistic trajectories from the point of convergence. These observations, and the fact that these geomorphological features occur only on unconsolidated soil close to the water table, make it plausible to propose that the Carolina Bays are the remodeled remains of oblique conical craters formed on ground liquefied by the seismic shock waves of secondary impacts of glacier ice boulders ejected by an extraterrestrial impact on the Laurentide Ice Sheet. Mathematical analysis using ballistic equations and scaling laws relating yield energy to crater size provide clues about the magnitude of the extraterrestrial event. An experimental model elucidates the remodeling mechanisms and provides an explanation for the morphology and the diverse dates of the bays.

  4. Impact of marine habitat changes on macro-benthos communities in Bohai Bay%渤海湾近海栖息地变化对大型底栖动物群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    张壮壮; 王琳; 杨文波; 曹坤; 李继龙

    2015-01-01

    and crustaceans, total species numbers in the macro-benthos, Shannon-wiener index, abundance index, and evenness index are all negatively correlated with each other. In contrast, mudflat, near-shore occupied shal-low water, coastline increase, polychaete proportions, total macro-benthos abundance and biomass were all positively correlated with each other. It is evident that changes in the marine habitat have had a significant impact on macro-benthos communities in Bohai Bay.

  5. Eutrophication influence on phytoplankton community composition in three bays on the eastern Adriatic coast

    Directory of Open Access Journals (Sweden)

    Mia Bužančić

    2016-10-01

    Full Text Available This study shows the influence of eutrophication pressure on the phytoplankton community structure, abundance and biodiversity in the investigated bays with different hydromorphological features. Šibenik Bay is a highly stratified estuary of the karstic river Krka; Kaštela Bay is a semi-enclosed coastal bay, which is influenced by the relatively small river Jadro; and Mali Ston Bay is located at the Neretva River estuary, the largest river on the eastern part of the Adriatic Sea. All of the areas are affected by urban pressure, which is reflected in the trophic status of the waters. The greatest anthropogenic influence was found in Kaštela Bay while the lowest influence was found in Mali Ston Bay. In this study, the highest biomass concentration and maximum abundance of phytoplankton were recorded at the stations under the strongest anthropogenic influence. Those stations show a dominance of abundance compared to the biomass and a dominance of opportunistic species, which is reflected in the lower biodiversity of phytoplankton community. Diatoms were the most represented group of the phytoplankton community in all three bays, followed by the dinoflagellates. Diatoms that were highlighted as significant for the difference between the bays were Skeletonema marinoi in Šibenik Bay, Leptocylindrus minimus in Kaštela Bay and the genus Chaetoceros spp. in Mali Ston Bay. Dinoflagellates were more abundant at the stations under the strongest anthropogenic influence, and most significant were Prorocentrum triestinum in Kaštela Bay and Gymnodinium spp. in Šibenik Bay and Mali Ston Bay.

  6. ANALYSIS ON IMPACT RESPONSES OF UNRESTRAINED PLANAR FRAME STRUCTURE(Ⅱ)-NUMERICAL EXAMPLE ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    CHEN Rong; ZHENG Hai-tao; XUE Song-tao; TANG He-sheng

    2005-01-01

    By using the formula derived in Part (Ⅰ), the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed.The impact force-time history between the structure and the moving rigid-body, shear force and bending moment distribution along the beams, axial force distribution along the bars were calculated. The wave propagation phenomena of the longitudinal wave in the bars, the flexural and shear waves in the beams were also analysed. The numerical results show that the time duration of impact force is controlled by the flexural wave and the longitudinal wave; the shear effect in beams should not be neglected in the impact response analysis of structures.

  7. Gravitationally induced particle production and its impact on structure formation

    CERN Document Server

    Nunes, Rafael C

    2016-01-01

    In this paper we investigate the influence of a continuous particles creation processes on the linear and nonlinear matter clustering, and its consequences on the weak lensing effect induced by structure formation. We study the line of sight behavior of the contribution to the bispectrum signal at a given angular multipole $l$, showing that the scale where the nonlinear growth overcomes the linear effect depends strongly of particles creation rate.

  8. The Oasis impact structure, Libya: geological characteristics from ALOS PALSAR-2 data interpretation

    Science.gov (United States)

    van Gasselt, Stephan; Kim, Jung Rack; Choi, Yun-Soo; Kim, Jaemyeong

    2017-02-01

    Optical and infrared remote sensing may provide first-order clues for the identification of potential impact structures on the Earth. Despite the free availability of at least optical image data at highest resolution, research has shown that remote sensing analysis always remains inconclusive and extensive groundwork is needed for the confirmation of the impact origin of such structures. Commonly, optical image data and digital terrain models have been employed mainly for such remote sensing studies of impact structures. With the advent of imaging radar data, a few excursions have been made to also employ radar datasets. Despite its long use, capabilities of imaging radar for studying surface and subsurface structures have not been exploited quantitatively when applied for the identification and description of such features due to the inherent complexity of backscatter processes. In this work, we make use of higher-level derived radar datasets in order to gain clearer qualitative insights that help to describe and identify potential impact structures. We make use of high-resolution data products from the ALOS PALSAR-1 and ALOS PALSAR-2 L-band sensors to describe the heavily eroded Oasis impact structure located in the Libyan Desert. While amplitude radar data with single polarization have usually been utilized to accompany the suite of remote sensing datasets when interpreting impact structures in the past, we conclude that the integration of amplitude data with HH/HV/HH-HV polarization modes in standard and, in particular, in Ultra-Fine mode, as well as entropy-alpha decomposition data, significantly helps to identify and discriminate surface units based on their consolidation. Based on the overarching structural pattern, we determined the diameter of the eroded Oasis structure at 15.6 ± 0.5 km.

  9. Experiencing the Impact of Organizational Structure on Planning and Visioning Tasks

    Science.gov (United States)

    Pennisi, Lisa

    2012-01-01

    The various ways natural resource agencies and programs are structured and how that impacts leadership style and products is an important concept for students to understand. Leadership style and organizational structure determine visions, missions, goals and objectives that set the tone for organizations. This exercise demonstrates organizational…

  10. Structural ambidexterity in NPD processes : A firm-level assessment of the impact of differentiated structures on innovation performance

    NARCIS (Netherlands)

    de Visser, Matthias; de Weerd-Nederhof, Petra; Faems, Dries; Song, Michael; van Looy, Bart; Visscher, Klaasjan

    2010-01-01

    Based on a survey study of 155 U.S. firms, we conducted a firm-level assessment of the impact of different kinds of structures (i.e., functional versus cross-functional) in different kinds of new product development (NPD) processes (i.e., incremental versus radical) on different kinds of firm innova

  11. Subsurface structure and kinematics of the Calaveras-Hayward fault stepover from three-dimensional Vp and seismicity, San Francisco Bay region, California

    Science.gov (United States)

    Manaker, David M.; Michael, Andrew J.; Burgmann, Roland

    2005-01-01

    The Calaveras and Hayward faults are major components of the San Andreas fault system in the San Francisco Bay region. Dextral slip is presumed to transfer from the Calaveras fault to the Hayward fault in the Mission Hills region, an area of uplift in the contractional stepover between the two faults. Here the estimated deep slip rates drop from 15 to 6 mm/yr on the Calaveras fault, and slip begins on the Hayward fault at an estimated 9 mm/yr. A lineament of microseismicity near the Mission fault links the seismicity on the Calaveras and Hayward faults and is presumed to be related directly to this slip transfer. However, geologic and seismologic evidence suggest that the Mission fault may not be the source of the seismicity and that the Mission fault is not playing a major role in the slip transfer.

  12. The Impact of Embedded Story Structures versus Sequential Story Structures on Critical Thinking of Iranian Intermediate EFL Learners

    Directory of Open Access Journals (Sweden)

    Sara Samadi

    2016-09-01

    Full Text Available Confirming the constructive effects of reading comprehension on critical thinking, this paper attempted to investigate the impact of story structures on critical thinking of Iranian EFL learners. In doing so, the researcher utilized a quasi–experimental design with 60 intermediate students who were divided into two embedded story structures and sequential story structures groups (experimental groups. After taking PET, a critical thinking questionnaire was employed as a pre-test. The two groups received 16 sessions of treatment. All participants received similar amount of instruction but one group was given embedded short stories and the other group sequential short stories. To compare the two groups, they were received the parallel critical thinking questionnaire as a post-test. The two null hypotheses in this study were rejected due to different performance of the two groups. Statistical results did not support the superiority of neither structures. Therefore, the researcher was not able to suggest which structure caused a better or higher impact on critical thinking. However, the findings reveal that teaching story structures in EFL context can develop critical thinking of intermediate EFL learners. The study have some implications for test-designers, teachers, and students. Keywords: Critical thinking, Embedded story structure, Sequential story structure, Reading comprehension

  13. The Transfinite High-rise Structure Design of Number 43 Floor in Zhongrong Xinghai Bay%中融星海湾43号楼超限高层结构设计

    Institute of Scientific and Technical Information of China (English)

    邹朝阳

    2013-01-01

    The number 43 floor project in Zhongrong Xinghai Bay is shear wal structure, the structure is 132.40 m high, whi-ch is a transfinite high-rise building. This article introduces the general situation of the project, seismic design objectives, etc., analyzes the structure under the different seismic force, and takes strengthening measures in the weak parts of structure to ensure the seismic safety of the structure.%  中融星海湾43号楼工程为剪力墙结构,结构高132.40 m,为超限高层建筑。本文介绍了该工程的概况、抗震设计目标等,对不同地震力作用下的结构进行了分析,对结构中存在的薄弱部位应采取加强措施,确保结构的抗震安全性。

  14. Impact of Point and Non-point Source Pollution on Coral Reef Ecosystems In Mamala Bay, Oahu, Hawaii based on Water Quality Measurements and Benthic Surveys in 1993-1994 (NODC Accession 0001172)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The effects of both point and non-point sources of pollution on coral reef ecosystems in Mamala Bay were studied at three levels of biological organization; the...

  15. Evaluating the impact of investments in information technology on structural inertia in health organizations.

    Science.gov (United States)

    Bewley, Lee W

    2010-01-01

    Structural inertia is the overall capacity of an organization to adapt within a market environment. This paper reviews the impact of healthcare investments in information management/information technology (IM/IT) on the strategic management concept of structural inertia. Research indicates that healthcare executives should consider the relative state of structural inertia for their firms and match them with potential IM/IT solutions. Additionally, organizations should favorably consider IM/IT solutions that are comparatively less complex.

  16. Damage criticality and inspection concerns of composite-metallic aircraft structures under blunt impact

    Science.gov (United States)

    Zou, D.; Haack, C.; Bishop, P.; Bezabeh, A.

    2015-04-01

    Composite aircraft structures such as fuselage and wings are subject to impact from many sources. Ground service equipment (GSE) vehicles are regarded as realistic sources of blunt impact damage, where the protective soft rubber is used. With the use of composite materials, blunt impact damage is of special interest, since potential significant structural damage may be barely visible or invisible on the structure's outer surface. Such impact can result in local or non-local damage, in terms of internal delamination in skin, interfacial delamination between stiffeners and skin, and fracture of internal reinforced component such as stringers and frames. The consequences of these events result in aircraft damage, delays, and financial cost to the industry. Therefore, it is necessary to understand the criticality of damage under this impact and provide reliable recommendations for safety and inspection technologies. This investigation concerns a composite-metallic 4-hat-stiffened and 5-frame panel, designed to represent a fuselage structure panel generic to the new generation of composite aircraft. The test fixtures were developed based on the correlation between finite element analyses of the panel model and the barrel model. Three static tests at certain amount of impact energy were performed, in order to improve the understanding of the influence of the variation in shear ties, and the added rotational stiffness. The results of this research demonstrated low velocity high mass impacts on composite aircraft fuselages beyond 82.1 kN of impact load, which may cause extensive internal structural damage without clear visual detectability on the external skin surface.

  17. Synthesis and Structure Control of A New Kind of Inelastomer Impact Modifier with Core-shell Structure and Impact Modification to PVC/CPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new kind of inelastomer impact modifier with a core-shell structure was synthesized by employing a multi-step composite emulsion polymerization technique, the size and morphology structure of the core-shell particles could be controlled by the multi-step composite emulsion polymerization technique. The study of the impact strength and the elongation at break of the PVC/CPE blend with different contents of core-shell particles(C-S) indicated that the mechanical properties of PVC/CPE/C-S composite were the best when the concentration of the particle was 2.5%(mass fraction) which showed the different regularities and characteristics of elastomer toughening plastic.

  18. Support for EU fundraising in the field of Environment & Energy - BayFOR

    Science.gov (United States)

    Ammerl, Thomas; Baumann, Cornelia; Reiter, Andrea; Blume, Andreas; Just, Jana; Franke, Jan

    2013-04-01

    The Bavarian Research Alliance (BayFOR, http://www.bayfor.org) is a private company for the support of Bavaria (Free State in the South East of Germany) as a centre for science and innovation within the European Research Area. It was set up on the initiative of the Bavarian universities to strengthen their networking at regional, national and international level while helping them to prepare to meet the requirements for European research funding. The focus is directed at the current EU Framework Programme (FP7) and the forthcoming Framework Programme for Research and Innovation "Horizon 2020", but also comprises the wide range of European programmes (e.g. FP7, LIFE+, Interreg, COST, EUREKA, ERA-Nets, IEE (CIP), LLP, Calls for tender). BayFOR is also a partner institution in the Bavarian "Haus der Forschung" (www.hausderforschung.bayern.de/en). BayFORs overall aim is to strengthen and permanently anchor the science and innovation location of Bavaria in the European Research Area through: a) Initiation of national and in particular European innovation and science partnerships from academia and business b) Improvement of innovation potential of Bavarian universities and SME c) Support in acquisition, management and dissemination of results of European and international projects in the field of research and technological development The service portfolio of the EU Funding Advisory Service reaches from the first project idea to project implementation. The minimum condition for BayFOR support is at least one partner from Bavaria (Germany) must be part of the applying consortium: a) Recommendation of funding programmes/instruments (incl. integration of relevant EU policies & directives) b) Partner search c) Project development and proposal elaboration (Online platform, Creation of consortium, Attendance at meetings, Preparation of documents, Proposal structure elaboration, Provision of templates, Editorial support: Gantt, PERT, Impact, EU added value) d) Support in the

  19. Impact of Aerodynamics and Structures Technology on Heavy Lift Tiltrotors

    Science.gov (United States)

    Acree, C. W., Jr.

    2006-01-01

    Rotor performance and aeroelastic stability are presented for a 124,000-lb Large Civil Tilt Rotor (LCTR) design. It was designed to carry 120 passengers for 1200 nm, with performance of 350 knots at 30,000 ft altitude. Design features include a low-mounted wing and hingeless rotors, with a very low cruise tip speed of 350 ft/sec. The rotor and wing design processes are described, including rotor optimization methods and wing/rotor aeroelastic stability analyses. New rotor airfoils were designed specifically for the LCTR; the resulting performance improvements are compared to current technology airfoils. Twist, taper and precone optimization are presented, along with the effects of blade flexibility on performance. A new wing airfoil was designed and a composite structure was developed to meet the wing load requirements for certification. Predictions of aeroelastic stability are presented for the optimized rotor and wing, along with summaries of the effects of rotor design parameters on stability.

  20. Evaluation of the Impact of the EU Structural Support on the Competitiveness of Lithuanian Economics

    Directory of Open Access Journals (Sweden)

    Rita Remeikiene

    2016-06-01

    Full Text Available Increasing amounts of the EU structural support in Lithuania require theoretical and practical research to disclose the determinants that have a significant impact on the competitiveness of Lithuanian economics. The purpose of this article is to evaluate the impact of the EU structural support on the competitiveness of Lithuanian economics. The methods of the research include systematic and comparative analysis of the scientific literature, expert evaluation and linear regression. The research disclosed the main determinants of country’s competitiveness. The results have revealed that EU structural support has the most significant impact on Lithuanian engineering and technological infrastructure. The impact of the support on country’s macroeconomic, scientific and social environment can also be considered as significant. The EU structural support has medium strong impact on education and business environment conditions in Lithuania. It has been established that, in the field of business advancement, Lithuanian should be rated as medium competitive. Hence, the increase in country’s competitiveness by employing EU structural funds should be treated as one of priority aims. In addition, responsible authorities should perform with higher efficiency seeking for higher competitiveness of the country.

  1. Local Impact Simulation of SC Wall Structures using Aircraft Engine Projectile

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chulhun; Lee, Jungwhee; Lee, Hanjoo [Dankook Univ., Yongin (Korea, Republic of); Jung, Raeyoung; Hyun, Changhun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    SC wall structure developed for nuclear power plant buildings consists of plain concrete and two steel plates on both surface of the concrete, while RC structure consists of re bar and concrete. SC structure has higher scabbing resistance than RC structure due to the action of steel plate on the rear side of impact. Therefore SC structure is known as more effective structure from the viewpoint of aircraft crash than RC structure. However, most of the recent researches and experiments about local impact damage deal with RC structures, and the effect of re bar and steel plate is not considered reasonably. Although Walter et al. and Make-work et al. suggested a formula for evaluating perforation depth of steel plate covered RC walls, most of the previous researches about SC structure are focused on perforation and scabbing due to the impact of hard projectile, rather than soft projectile such as an aircraft. In this research a soft projectile, i. e. aircraft engine, is utilized for impact simulation of RC and SC walls. To evaluate local damage of SC wall structures, parametric study with the variables of wall thickness and steel ratio of the cover plate is performed, and the results are compared with those of RC structures. Since scabbing was prevented by the steel plates, penetration mode of damage was observed in SC walls while scabbing damage was occurred in RC walls. It is confirmed that the rear steel plate not only contains concrete debris, but also reduces the internal damage of the concrete walls. Penetration depth of SC walls did not largely vary due to the increasing steel ratio, and similar results to RC walls were observed when the wall thickness is larger than a certain value since the impact resistance of SC wall is mainly governed by the thickness of concrete part. Therefore, it is expected that similar level of impact resistance to RC structure can be produced with the minimum thickness of steel plates of SC structure. According to these results, SC

  2. Bayes linear covariance matrix adjustment

    CERN Document Server

    Wilkinson, Darren J

    1995-01-01

    In this thesis, a Bayes linear methodology for the adjustment of covariance matrices is presented and discussed. A geometric framework for quantifying uncertainties about covariance matrices is set up, and an inner-product for spaces of random matrices is motivated and constructed. The inner-product on this space captures aspects of our beliefs about the relationship between covariance matrices of interest to us, providing a structure rich enough for us to adjust beliefs about unknown matrices in the light of data such as sample covariance matrices, exploiting second-order exchangeability and related specifications to obtain representations allowing analysis. Adjustment is associated with orthogonal projection, and illustrated with examples of adjustments for some common problems. The problem of adjusting the covariance matrices underlying exchangeable random vectors is tackled and discussed. Learning about the covariance matrices associated with multivariate time series dynamic linear models is shown to be a...

  3. The Liverpool Bay Coastal Observatory

    Science.gov (United States)

    Howarth, John; Palmer, Matthew

    2011-11-01

    A pilot Coastal Observatory has been established in Liverpool Bay which integrates (near) real-time measurements with coupled models and whose results are displayed on the web. The aim is to understand the functioning of coastal seas, their response to natural forcing and the consequences of human activity. The eastern Irish Sea is an apt test site, since it encompasses a comprehensive range of processes found in tidally dominated coastal seas, including near-shore physical and biogeochemical processes influenced by estuarine inflows, where both vertical and horizontal gradients are important. Applications include hypernutrification, since the region receives significantly elevated levels of nutrient inputs, shoreline management (coastal flooding and beach erosion/accretion), and understanding present conditions to predict the impact of climate change (for instance if the number and severity of storms, or of high or low river flows, change). The integrated measurement suite which started in August 2002 covers a range of space and time scales. It includes in situ time series, four to six weekly regional water column surveys, an instrumented ferry, a shore-based HF radar system measuring surface currents and waves, coastal tide gauges and visible and infra-red satellite data. The time series enable definition of the seasonal cycle, its inter-annual variability and provide a baseline from which the relative importance of events can be quantified. A suite of nested 3D hydrodynamic, wave and ecosystem models is run daily, focusing on the observatory area by covering the ocean/shelf of northwest Europe (at 12-km resolution) and the Irish Sea (at 1.8 km), and Liverpool Bay at the highest resolution of 200 m. The measurements test the models against events as they happen in a truly 3D context. All measurements and model outputs are displayed freely on the Coastal Observatory website (http://cobs.pol.ac.uk) for an audience of researchers, education, coastal managers and the

  4. Environmental impact of aquaculture - sedimentation and nutrient loadings from shrimp culture of the southeast coastal region of the Bay of Bengal

    Institute of Scientific and Technical Information of China (English)

    Biplob Das; Yusuf Sharif Ahmed Khan; Pranab Das

    2004-01-01

    Nutrient loadings were measured for surface seawater and bottom sediments of semi-intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south-east coastal region of Bangladesh during August, 2000 - January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108.780 mg/L for CaCO3, 0.526 mg/L for NH4+-N, 3.075 wt% for organic carbon, 7.00 mg/L for PO4-P, 5.57 mg/L for NO3-N, and 7.33 mg/L for chlorophyll-a. The maximum mean value of H2S(0.232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration(550.33 ppt) in adjacent fallow land, as; the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H2S value and sediment pH (r = - 0.94); sediment organic carbon and sediment pH values (r = - 0.76), sediment total nitrogen and sediment pH (r = - 0.74) were found to be highly negatively correlated. Whereas the relation between seawater H2S value and sediment total nitrogen (r = 0.92), water NH4+-N and sediment pH (r = 0.66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.

  5. Spring and Summer Fish Community Structure in Northern Hangzhou Bay%春季和夏季杭州湾北部海域鱼类种群结构分析

    Institute of Scientific and Technical Information of China (English)

    王淼; 洪波; 张玉平; 孙振中

    2016-01-01

    Hangzhou Bay,located in northern Zhejiang Province,is a typical subtropical estuary,supporting the breeding and growth of many fish,shrimp and crab species because of rich food resources.However,coastal indus-trial pollution and overfishing in recent years has seriously damaged the marine environment and fishery resources in the Hangzhou.The fishery resource is tending toward smaller and younger fish and some economic fish are declining or have disappeared,perhaps leading to collapse of the marine ecosystem.Therefore,information on current fish stocks and the condition of the marine environment in Hangzhou Bay is important for ecological remediation efforts. The fish community structure in northern Hangzhou Bay was characterized,based on a field investigation of fish re-sources in August of 2012 and May of 2013.The investigation focused on species composition and seasonal variation of the fish community structure in spring and summer.Study methods included the index of relative importance, cluster analysis,and multivariate statistics and the relationship between the fish community and environmental fac-tors was analyzed.Fish were collected at 12 sampling stations by trawling with a 25 m net with an opening of 10m and net mesh of 20 mm.The trawling was carried out at a speed of 2.5 knots for 15 -30 min at each station and water temperature,salinity and depth were recorded.A total of 22 fish species were collected during spring and summer sampling,including 19 genera,12 families and 8 orders.Perciformes dominated,accounting for 50% of the total fish species,followed by Pleuronectiformes and Clupeiformes,both accounting for 13.6%.The ecological groups included marine,estuarine and anadromous fish,with absolute dominance by marine fish (13 species).Six dominant species were identified:in the spring,Collichthys lucidus,Miichthys miiuy,Coilia mystus;in summer,Col-lichthys lucidus,Pennahia argentata,Harpodon nehereus,Miichthys miiuy and Cynoglossus joyneri

  6. The influence of finfish aquaculture on benthic fish and crustacean assemblages in Fitzgerald Bay, South Australia.

    Science.gov (United States)

    Tanner, Jason E; Williams, Kane

    2015-01-01

    The influence of sea-cage aquaculture on wildfish assemblages has received little attention outside of Europe. Sea-cage aquaculture of finfish is a major focus in South Australia, and while the main species farmed is southern bluefin tuna (Thunnus maccoyii), there is also an important yellowtail kingfish (Seriola lalandi) industry. Yellowtail kingfish aquaculture did not appear to have any local or regional effects on demersal assemblages (primarily fish, but also some crustaceans) surveyed by baited remote underwater video (BRUV) in Fitzgerald Bay. We did, however, detect small scale spatial variations in assemblages within the bay. The type of bait used strongly influenced the assemblage recorded, with significantly greater numbers of fish attracted to deployments where sardines were used as the bait to compared to those with no bait. The pelleted feed used by the aquaculture industry was just as attractive as sardines at one site, and intermediate between sardines and no bait at the other. There was significant temporal variability in assemblages at both farm sites and one control site, while the second control site was temporally stable (over the 9 weeks of the study). Overall, the results suggested that aquaculture was having little if any impact on the abundance and assemblage structure of the demersal macrofauna in Fitzgerald Bay.

  7. The convincing identification of terrestrial meteorite impact structures: What works, what doesn't, and why

    Science.gov (United States)

    French, Bevan M.; Koeberl, Christian

    2010-01-01

    In the geological sciences it has only recently been recognized how important the process of impact cratering is on a planetary scale, where it is commonly the most important surface-modifying process. On the Moon and other planetary bodies that lack an appreciable atmosphere, meteorite impact craters are well preserved, and they can commonly be recognized from morphological characteristics, but on Earth complications arise as a consequence of the weathering, obliteration, deformation, or burial of impact craters and the projectiles that formed them. These problems made it necessary to develop diagnostic criteria for the identification and confirmation of impact structures on Earth. Diagnostic evidence for impact events is often present in the target rocks that were affected by the impact. The conditions of impact produce an unusual group of melted, shocked, and brecciated rocks, some of which fill the resulting crater, and others which are transported, in some cases to considerable distances from the source crater. Only the presence of diagnostic shock-metamorphic effects and, in some cases, the discovery of meteorites, or traces thereof, is generally accepted as unambiguous evidence for an impact origin. Shock deformation can be expressed in macroscopic form (shatter cones) or in microscopic forms (e.g., distinctive planar deformation features [PDFs] in quartz). In nature, shock-metamorphic effects are uniquely characteristic of shock levels associated with hypervelocity impact. The same two criteria (shock-metamorphic effects or traces of the impacting meteorite) apply to distal impact ejecta layers, and their presence confirms that materials found in such layers originated in an impact event at a possibly still unknown location. As of 2009 about 175 impact structures have been identified on Earth based on these criteria. A wide variety of shock-metamorphic effects has been identified, with the best diagnostic indicators for shock metamorphism being features

  8. Network structure impacts global commodity trade growth and resilience

    Science.gov (United States)

    Rovenskaya, Elena; Fath, Brian D.

    2017-01-01

    Global commodity trade networks are critical to our collective sustainable development. Their increasing interconnectedness pose two practical questions: (i) Do the current network configurations support their further growth? (ii) How resilient are these networks to economic shocks? We analyze the data of global commodity trade flows from 1996 to 2012 to evaluate the relationship between structural properties of the global commodity trade networks and (a) their dynamic growth, as well as (b) the resilience of their growth with respect to the 2009 global economic shock. Specifically, we explore the role of network efficiency and redundancy using the information theory-based network flow analysis. We find that, while network efficiency is positively correlated with growth, highly efficient systems appear to be less resilient, losing more and gaining less growth following an economic shock. While all examined networks are rather redundant, we find that network redundancy does not hinder their growth. Moreover, systems exhibiting higher levels of redundancy lose less and gain more growth following an economic shock. We suggest that a strategy to support making global trade networks more efficient via, e.g., preferential trade agreements and higher specialization, can promote their further growth; while a strategy to increase the global trade networks’ redundancy via e.g., more abundant free-trade agreements, can improve their resilience to global economic shocks. PMID:28207790

  9. Workplace experience of radiographers: impact of structural and interpersonal interventions

    Energy Technology Data Exchange (ETDEWEB)

    Kubik-Huch, R.A.; Roempler, M.; Weber, A. [Kantonsspital Baden, Institute of Radiology, Baden (Switzerland); Klaghofer, R.; Buddeberg-Fischer, B. [Zurich University Hospital, Department of Psychosocial Medicine, Zurich (Switzerland)

    2010-02-15

    Within the framework of organisational development, an assessment of the workplace experience of radiographers (RGs) was conducted. The aims of this study were to develop structural and interpersonal interventions and to prove their effectiveness and feasibility. A questionnaire consisting of work-related factors, e.g. time management and communication, and two validated instruments (Workplace Analysis Questionnaire, Effort-Reward Imbalance Scale) was distributed to all RGs (n = 33) at baseline (T1). Interventions were implemented and a follow-up survey (T2) was performed 18 months after the initial assessment. At T1, areas with highest dissatisfaction were communication and time management for ambulant patients (bad/very bad, 57% each). The interventions addressed adaptation of work plans, coaching in developing interpersonal and team leadership skills, and regular team meetings. The follow-up survey (T2) showed significantly improved communication and cooperation within the team and improved qualification opportunities, whereas no significant changes could be identified in time management and in the workplace-related scales 'effort' expended at work and 'reward' received in return for the effort. Motivating workplace experience is important for high-level service quality and for attracting well-qualified radiographers to work at a place and to stay in the team for a longer period. (orig.)

  10. Geophysical characterization of two circular structures at Bajada del Diablo (Patagonia, Argentina): Indication of impact origin

    Science.gov (United States)

    Prezzi, Claudia B.; Orgeira, María Julia; Acevedo, Rogelio D.; Ponce, Juan Federico; Martinez, Oscar; Rabassa, Jorge O.; Corbella, Hugo; Vásquez, Carlos; González-Guillot, Mauricio; Subías, Ignacio

    2012-02-01

    An impact origin has been proposed for the circular structures found in Bajada del Diablo, Patagonia, Argentina. Taking into account its extension and the number of impact structures, Bajada del Diablo would be the largest meteoritic impact areas known on Earth, being an extremely interesting area for the research of impact events and processes. Moreover, the global distribution of known impact structures shows a surprising asymmetry. Particularly, South America has only seven described areas. It is evident that this situation is an artifact, highlighting the importance of intensifying the research in the least studied areas such as Argentina. Circular structures in Bajada del Diablo have been identified on two rock types: the Quiñelaf eruptive complex and Pampa Sastre Formation. In the first case, circular structures are placed in olivine basalts. On the other hand, Pampa Sastre Formation (late Pliocene/early Pleistocene) corresponds to conglomerate layers with basalt clasts boulder and block in size in a coarse sandy matrix. With the aim of further the investigation of the proposed impact origin for these circular structures, we carried out detailed topographic, magnetic and electromagnetic ground surveys in two circular structures ("8" and "A") found in Pampa Sastre conglomerates. Both circular structures are simple, bowl-shaped with rim diameters of 300 m and maximum depths of 10 m. They have been partially filled in by debris flows from the rims and wind-blown sands. Two preliminary magnetic profiles have also been carried out in circular structure "G" found in Quiñelaf basalts. The magnetic anomalies show a circular pattern with a slightly negative and relatively flat signal in the circular structures' bases. Furthermore in the circular structures' rims, high-amplitude, conspicuous and localized (short wavelength) anomalies are observed. Such large amplitude and short wavelength anomalies are not detected outside the circular structures. For all used

  11. Impact Resistance of Structural Ceramics. Part 1. Instrumented Drop- Weight Tests

    Science.gov (United States)

    1976-05-01

    instrumented Charpy test and the instrumented DWT. The Impact Fracture Energy of a ceramic is determined by its dynamic strength. At room temperature...AFML-TR-76-56 ~I’S PART I 0 IMPACT RESISTANCE OF STRUCTURAL CERAMICS PART I: INSTRUMENTED DROP-WEIGHT TESTS PROCESSING AND HIGH TEMPERATURE MATERIALS...BLAG..OTP ,fIJMED .. TABLE OF CONTENTS SECTION PAGE I INTRODUCTION 1 II DROP-WEIGHT TEST (DWT) 3 III EXPERIMENTAL PROCEDURES FOR THE INSTRUMENTED DWT AT

  12. CIRIR Programs: Drilling and Research Opportunities at the Rochechouart Impact Structure

    Science.gov (United States)

    Lambert, P.; Alwmark, C.; Baratoux, D.; Brack, A.; Bruneton, P.; Buchner, E.; Claeys, P.; Dence, M.; French, B.; Hoerz, F

    2017-01-01

    Owing to its size, accessibility and erosional level, the Rochechouart impact structure, dated at 203 +/- 2 Ma (recalc.), is a unique reser-voir of knowledge within the population of the rare terrestrial analogous to large impacts craters observed on planetary surfaces. The site gives direct access to fundamental mechanisms both in impact-related geology (origin and evolution of planets) and biology (habitability of planets, emergence and evolution of life). For the last decade P. Lambert has been installing Rochechouart as International Natural Laboratory for studying impact processes and collateral effects on planetary surfaces. For this purpose the Center for International Research on Impacts and on Rochechouart (CIRIR) was installed on site in 2016 with twofold objectives and activities. First ones are scientific and dedicated to the scientific community. The second are cultural and educational and are dedi-cated to the public sensu lato. We present here the CIRIR, its scientific programs and the related reseach opportunities.

  13. Augmented Reality to Support On-Field Post-Impact Maintenance Operations on Thin Structures

    Directory of Open Access Journals (Sweden)

    Luca De Marchi

    2013-01-01

    monitored and a signal processing algorithm (the Warped Frequency Transform able to compensate for dispersion the acquired waveforms. The compensated waveforms yield to a robust estimation of Lamb waves difference in distance of propagation (DDOP, used to feed hyperbolic algorithms for impact location determination, and allow an estimation of the uncertainty of the impact positioning as well as of the impact energy. The outputs of the impact methodology are passed to a visualization technology that yielding their representation in Augmented Reality (AR is meant to support the inspector during the on-field inspection/diagnosis as well as the maintenance operations. The inspector, in fact, can see interactively in real time the impact data directly on the surface of the structure. To validate the proposed approach, tests on an aluminum plate are presented. Results confirm the feasibility of the method and its exploitability in maintenance practice.

  14. Generating spatial precipitation ensembles: impact of temporal correlation structure

    Directory of Open Access Journals (Sweden)

    O. Rakovec

    2012-09-01

    Full Text Available Sound spatially distributed rainfall fields including a proper spatial and temporal error structure are of key interest for hydrologists to force hydrological models and to identify uncertainties in the simulated and forecasted catchment response. The current paper presents a temporally coherent error identification method based on time-dependent multivariate spatial conditional simulations, which are conditioned on preceding simulations. A sensitivity analysis and real-world experiment are carried out within the hilly region of the Belgian Ardennes. Precipitation fields are simulated for pixels of 10 km × 10 km resolution. Uncertainty analyses in the simulated fields focus on (1 the number of previous simulation hours on which the new simulation is conditioned, (2 the advection speed of the rainfall event, (3 the size of the catchment considered, and (4 the rain gauge density within the catchment. The results for a sensitivity analysis show for typical advection speeds >20 km h−1, no uncertainty is added in terms of across ensemble spread when conditioned on more than one or two previous hourly simulations. However, for the real-world experiment, additional uncertainty can still be added when conditioning on a larger number of previous simulations. This is because for actual precipitation fields, the dynamics exhibit a larger spatial and temporal variability. Moreover, by thinning the observation network with 50%, the added uncertainty increases only slightly and the cross-validation shows that the simulations at the unobserved locations are unbiased. Finally, the first-order autocorrelation coefficients show clear temporal coherence in the time series of the areal precipitation using the time-dependent multivariate conditional simulations, which was not the case using the time-independent univariate conditional simulations. The presented work can be easily implemented within a hydrological calibration and data assimilation

  15. Energy Analysis for TMD-Structure Systems Subjected to Impact Loading

    Institute of Scientific and Technical Information of China (English)

    王树青; 李华军; 嵇春艳; 焦桂英

    2002-01-01

    This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focnses on theenergy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplifiedsingle-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force isassumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied.Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the standard deviation of thedeck motion but less effective in reducing the maximum response under impact loading.

  16. Remarks on kernel Bayes' rule

    OpenAIRE

    Johno, Hisashi; Nakamoto, Kazunori; Saigo, Tatsuhiko

    2015-01-01

    Kernel Bayes' rule has been proposed as a nonparametric kernel-based method to realize Bayesian inference in reproducing kernel Hilbert spaces. However, we demonstrate both theoretically and experimentally that the prediction result by kernel Bayes' rule is in some cases unnatural. We consider that this phenomenon is in part due to the fact that the assumptions in kernel Bayes' rule do not hold in general.

  17. Shatter cones at the Keurusselkä impact structure and their relation to local jointing

    Science.gov (United States)

    Hasch, Maximilian; Reimold, Wolf Uwe; Raschke, Ulli; Zaag, Patrice Tristan

    2016-08-01

    Shatter cones are the only distinct meso- to macroscopic recognition criterion for impact structures, yet not all is known about their formation. The Keurusselkä impact structure, Finland, is interesting in that it presents a multitude of well-exposed shatter cones in medium- to coarse-grained granitoids. The allegedly 27 km wide Keurusselkä impact structure was formed about 1150 Ma ago in rocks of the Central Finland Granitoid Complex. Special attention was paid in this work to possible relationships between shatter cones and local, as well as regionally occurring, fracture or joint systems. A possible shatter cone find outside the previously suggested edge of the structure could mean that the Keurusselkä impact structure is larger than previously thought. The spacing between joints/fractures from regional joint systems was influenced by the impact, but impact-induced fractures strongly follow the regional joint orientation trends. There is a distinct relationship between shatter cones and joints: shatter cones occur on and against joint surfaces of varied orientations and belonging to the regional orientation trends. Planar fractures (PF) and planar deformation features (PDF) were found in three shatter cone samples from the central-most part of the impact structure, whereas other country rock samples from the same level of exposure but further from the assumed center lack shock deformation features. PDF occurrence is enhanced within 5 mm of shatter cone surfaces, which is interpreted to suggest that shock wave reverberation at preimpact joints could be responsible for this local enhancement of shock deformation. Some shatter cone surfaces are coated with a quasi-opaque material which is also found in conspicuous veinlets that branch off from shatter cone surfaces and resemble pseudotachylitic breccia veins. The vein-filling is composed of two mineral phases, one of which could be identified as a montmorillonitic phyllosilicate. The second phase could not be

  18. Low-Cost Impact Detection and Location for Automated Inspections of 3D Metallic Based Structures

    Directory of Open Access Journals (Sweden)

    Carlos Morón

    2015-05-01

    Full Text Available This paper describes a new low-cost means to detect and locate mechanical impacts (collisions on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach.

  19. BCDC Bay Trail Alignment 2009

    Data.gov (United States)

    California Department of Resources — The Bay Trail provides easily accessible recreational opportunities for outdoor enthusiasts, including hikers, joggers, bicyclists and skaters. It also offers a...

  20. Deep bore hole instrumentation along San Francisco Bay Bridges

    Energy Technology Data Exchange (ETDEWEB)

    Bakun, W.; Bowman, J.; Clymer, R.; Foxall, W.; Hipley, P.; Hollfelder, J.; Hutchings, L.; Jarpe, S.; Kasameyer, P.; McEvilly, T.; Mualchin, L.; Palmer, M.

    1998-10-01

    The Bay Bridges down hole network consists of sensors in bore holes that are drilled 100 ft. into bedrock around and in the San Francisco Bay. Between 2 and 8 instruments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty- one sensor packages at fifteen sites. Extensive financial support is being contributed by Caltrans, UCB, LBL, LLNL-LDRD, U.C. Campus/Laboratory Collaboration (CLC) program, and USGS. The down hole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 73 1 accelerometers, and is capable of recording a micro g from local M = 1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes.

  1. Deep Borehole Instrumentation Along San Francisco Bay Bridges - 2001

    Energy Technology Data Exchange (ETDEWEB)

    Hutchings, L.; Kasameyer, P.; Long, L.; McEvilly, T.; Clymer, R.; Urhhammer, R.; Baise, L.

    2001-05-01

    This is a progress report on the Bay Bridges downhole network. Between 2 and 8 instruments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges in San Francisco Bay, California. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty-one sensor packages at fifteen sites. The downhole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 731 accelerometers, and is capable of recording a micro g from local M = 1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes. This report list earthquakes and stations where recordings were obtained during the period February 29, 2000 to November 11, 2000. Also, preliminary results on noise analysis for up and down hole recordings at Yerba Buena Island is presented.

  2. The Voisey's Bay Ni-Cu-Co Sulfide Deposit,Labrador,Canada:Emplacement of Silicate and Sulfide-Laden Magmas into Spaces Created within a Structural Corridor%The Voisey's Bay Ni-Cu-Co Sulfide Deposit,Labrador, Canada: Emplacement of Silicate and Sulfide-Laden Magmas into Spaces Created within a Structural Corridor

    Institute of Scientific and Technical Information of China (English)

    Peter C.Lightfoot; Dawn Evans-Lamswood; Robert Wheeler

    2012-01-01

    Abstract:The Voisey's Bay Ni-Cu-Co sulfide deposit is hosted in a 1.34 Ga mafic intrusion that is part of the Nain Plutonic Suite in Labrador,Canada.The Ni-Cu-Co sulfide mineralization is associated with magmatic breccias that are typically contained in weakly mineralized olivine gabbros,troctolites and ferrogabbros,but also occur as veins in adjacent paragneiss.The mineralization is associated with a dyke-like body which is termed the feeder dyke.This dyke connects the shallow differentiated Eastern Deeps chamber in the east to a deeper intrusion in the west termed the Western Deeps Intrusion.Where the conduit is connected to the Eastern Deeps Intrusion,the Eastern Deeps Deposit is developed at the entry line of the dyke along the steep north wall of the Eastern Deeps Intrusion.The Eastern Deeps Deposit is surrounded by a halo of moderately to weakly mineralized Variable-Textured Troctolite (VTT) that reaches a maximum thickness above the ENE-WSW axis of the Eastern Deeps Deposit.At depth to the west,the conduit is adjacent to the south side of the Western Deeps Intrusion,where the dyke and intrusion contain disseminated magmatic sulfide mineralization.The Reid Brook Zone plunges to the east within the dyke,and both the dyke and adjacent paragneiss are mineralized.The Ovoid Deposit comprises a bowl-shaped body of massive sulfide where the dyke widens near to the present-day surface.It is not clear whether this deposit was developed as a widened-zone within the conduit or at the entry point into a chamber that is now lost to erosion.The massive sulfides and breccia sulfides of the Eastern Deeps are petrologically and chemically different when compared to the disseminated sulfides in the VTT; there is a marked break in Ni tenor (Ni content in 100% sulfide,abbreviated to [Ni] 100) and Ni/Co of sulfide between the two.The boundary of the sulfide types is often marked by strong sub-horizontal alignment of heavily digested and metamorphosed paragneiss fragments

  3. The Impact of Organizational Structure on Internal and External Integration: An empirical, cross-regional assessment

    Directory of Open Access Journals (Sweden)

    Xenophon Koufteros

    2014-06-01

    Full Text Available We examine the effects of organizational structure on cross-functional integration, supplier integration, and customer integration and assess whether such effects vary by geographical region. Specifically, we investigate the impact of centralization, formalization, and complexity on both internal (cross-functional and external (supplier, customer integration. Relationships are examined across Western and East Asian environments using data collected from 238 manufacturing plants in eight countries. We find that structural features have differing impacts on cross-functional, supplier, and customer integration, and these effects vary across geographical regions.

  4. Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation.

    Science.gov (United States)

    Izawa, M R M; Banerjee, Neil R; Osinski, G R; Flemming, R L; Parnell, J; Cockell, C S

    2011-01-01

    Meteorite impacts are among the very few processes common to all planetary bodies with solid surfaces. Among the effects of impact on water-bearing targets is the formation of post-impact hydrothermal systems and associated mineral deposits. The Haughton impact structure (Devon Island, Nunavut, Canada, 75.2 °N, 89.5 °W) hosts a variety of hydrothermal mineral deposits that preserve assemblages of primary hydrothermal minerals commonly associated with secondary oxidative/hydrous weathering products. Hydrothermal mineral deposits at Haughton include intra-breccia calcite-marcasite vugs, small intra-breccia calcite or quartz vugs, intra-breccia gypsum megacryst vugs, hydrothermal pipe structures and associated surface "gossans," banded Fe-oxyhydroxide deposits, and calcite and quartz veins and coatings in shattered target rocks. Of particular importance are sulfide-rich deposits and their associated assemblage of weathering products. Hydrothermal mineral assemblages were characterized structurally, texturally, and geochemically with X-ray diffraction, micro X-ray diffraction, optical and electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Primary sulfides (marcasite and pyrite) are commonly associated with alteration minerals, including jarosite (K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6), rozenite FeSO(4)·4(H(2)O), copiapite (Fe,Mg)Fe(4)(SO(4))(6)(OH)(2)·20(H(2)O), fibroferrite Fe(SO(4))(OH)·5(H(2)O), melanterite FeSO(4)·7(H(2)O), szomolnokite FeSO(4)·H(2)O, goethite α-FeO(OH), lepidocrocite γ-FeO(OH) and ferrihydrite Fe(2)O(3)·0.5(H(2)O). These alteration assemblages are consistent with geochemical conditions that were locally very different from the predominantly circumneutral, carbonate-buffered environment at Haughton. Mineral assemblages associated with primary hydrothermal activity, and the weathering products of such deposits, provide constraints on possible microbial activity in the post-impact environment. The initial period of

  5. Review: Impact of underground structures on the flow of urban groundwater

    Science.gov (United States)

    Attard, Guillaume; Winiarski, Thierry; Rossier, Yvan; Eisenlohr, Laurent

    2016-02-01

    Property economics favours the vertical development of cities but flow of groundwater can be affected by the use of underground space in them. This review article presents the state of the art regarding the impact of disturbances caused by underground structures (tunnels, basements of buildings, deep foundations, etc.) on the groundwater flow in urban aquifers. The structures built in the underground levels of urban areas are presented and organised in terms of their impact on flow: obstacle to the flow or disturbance of the groundwater budget of the flow system. These two types of disturbance are described in relation to the structure area and the urban area. The work reviewed shows, on one hand, the individual impacts of different urban underground structures, and on the other, their cumulative impacts on flow, using real case studies. Lastly, the works are placed in perspective regarding the integration of underground structures with the aim of operational management of an urban aquifer. The literature presents deterministic numerical modelling as a tool capable of contributing to this aim, in that it helps to quantify the effect of an underground infrastructure project on groundwater flow, which is crucial for decision-making processes. It can also be an operational decision-aid tool for choosing construction techniques or for formulating strategies to manage the water resource.

  6. The Peerless structure, Daniels County, northeastern Montana: A probable late Ordovician impact structure

    Science.gov (United States)

    Comstock, J. M.; Dietz, R. D.; Morrow, J. R.

    2004-05-01

    The Peerless structure is an ~6 km-diameter sub-surface anomaly located in Daniels County, northeastern Montana. The disruption of sedimentary rock in the structure lies between 2624 to 2818 m below the topographic surface. Seismic mapping shows a typical complex crater composed of a central uplift ~2 km across, which shows structural uplift of up to 90 m, an annular ring ~4 km across, and an outer rim ~6 km in diameter. The youngest disrupted rock unit is the upper Ordovician Red River formation, which indicates that the structure was formed about 430-450 Ma ago.

  7. Impact of freshwater on a subarctic coastal ecosystem under seasonal sea ice (southeastern Hudson Bay, Canada). I. Interannual variability and predicted global warming influence on river plume dynamics and sea ice

    Science.gov (United States)

    Ingram, R. G.; Wang, J.; Lin, C.; Legendre, L.; Fortier, L.

    1996-02-01

    Analysis of sea ice cover, runoff and air temperature observations in Hudson Bay shows marked interannual variability. This variability is thought to play a major role in determining overall productivity of the coastal ecosystem by changes to river plume extent, under-ice light conditions and nutrient levels during spring. Extensive field work off the Great Whale River in southeastern Hudson Bay has shown the importance of freshwater discharge, sea ice cover and meteorological forcing on the production of under-ice microalgae and the success of first feeding in fish larvae. Recent global climate model (GCM) results for a doubling of present atmospheric carbon dioxide indicate increases of both air temperature and precipitation in the Hudson Bay area. Predictions based on GCM results are used to estimate future changes to the sea ice and runoff regime. Sea ice breakup in the offshore is predicted to occur about one month earlier than presently. Estimates of the spring freshet in the Great Whale River indicate it will also advance by approximately one month. Onset of the spring freshet will occur about one month before Hudson Bay ice breakup, similar to present. A predicted reduction of about 35% in maximum sea ice thickness will lead to an increase in the ice-ocean interface irradiance and a decrease in melt water input to the Hudson Bay surface waters. These results are used in a discussion of potential effects of global climate change on northern coastal marine environments.

  8. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ellingwood, B.; Song, J. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  9. Visualizing impact structures using high-resolution LiDAR-derived DEMs: A case study of two structures in Missouri

    Science.gov (United States)

    Finn, Michael P.; Krizanich, Gary W.; Evans, Kevin R.; Cox, Melissa R.; Yamamoto, Kristina H.

    2015-01-01

    Evidence suggests that a crypto-explosive hypothesis and a meteorite impact hypothesis may be partly correct in explaining several anomalous geological features in the middle of the United States. We used a primary geographic information science (GIScience) technique of creating a digital elevation model (DEM) of two of these features that occur in Missouri. The DEMs were derived from airborne light detection and ranging, or LiDAR. Using these DEMs, we characterized the Crooked Creek structure in southern Crawford County and the Weaubleau structure in southeastern St. Clair County, Missouri. The mensuration and study of exposed and buried impact craters implies that the craters may have intrinsic dimensions which could only be produced by collision. The results show elevations varying between 276 and 348 m for Crooked Creek and between 220 and 290 m for Weaubleau structure. These new high- resolution DEMs are accurate enough to allow for precise measurements and better interpretations of geological structures, particularly jointing in the carbonate rocks, and they show greater definition of the central uplift area in the Weaubleau structure than publicly available DEMs.

  10. 大亚湾春秋季鱼类种类组成及年龄结构分析%Species composition and age structure of fish in the Dava Bay in spring and autumn

    Institute of Scientific and Technical Information of China (English)

    金亮; 徐华林; 张志敏; 杨锡凯; 王英永; 卢昌义

    2011-01-01

    2006年4月和9月对大亚湾海域通过拖网和流刺网捕获的鱼类进行初步调查.结果表明,渔获物中出现18目76科135属200种鱼类,其中软骨鱼纲4目5科5属6种,占调查鱼类总种数的3.0%;硬骨鱼纲14目71科130属194种,占调查鱼类总种数的97.0%.根据其适温类型可分为暖水性种、暖温性种和冷温性种,其中暖水性鱼类有183种,占总种数的91.5%;暖温性鱼类有16种,占总种数的8.0%;冷温性鱼类仅有1种,占总种数的0.5%.渔获物中底层和近底层鱼类占多数,其中,底层鱼类共有74种,占总种数的37.0%;近底层鱼类共有68种,占总种数的34.0%;中上层鱼类共有45种,占总种数的22.5%;岩礁鱼类有13种,占总种数的6.5%.大亚湾鱼类的年龄普遍偏低,以1 a龄鱼为主.与相邻海区鱼类区系特征比较,大亚湾海域具有我国热带和亚热带性海湾的鱼类区系特征.%An investigation of fish in Daya Bay was conducted in April and September 2006 using a trawl and drift net. The results showed that there were 200 species of fish belonging to 135 genera in 76 families of 18 orders. Of these, 6 species in 5 genera, 5 families, and 4 orders belonged to Chondrichthyes, and 194 species in 130 genera,71 families, and 14 orders belonged to Osteiehthyes, accounting for 3.0% and 97.0%, respectively. Based on the temperature nature of the fauna, the fish in Daya Bay may be grouped into three types, with warm-water species,warm-temperature species and cold-temperature species accounting for 91.5% ( 183 species), 8.0% ( 16 species) and 0. 5% ( one species), respectively. According to the diversity of the habitable environment, demersal fishes were the most abundant, accounting for 37.0% (74 species), followed by near demersal and pelagic fish, accounting for 34.0% (68 species) and 22. 5% (45 species ), respectively, and reef fish only accounted for 6.5% ( 13 species). The age structure of the fish primarily consisted of one age

  11. Particle-fluid-structure interaction for debris flow impact on flexible barriers

    OpenAIRE

    A. Leonardi; Wittel, F. K.; Mendoza, M.; Vetter, R.; Herrmann, H.J.

    2014-01-01

    Flexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, a numerical tool for rational design of such structures is still missing. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the Finite Element Method (FEM) to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of t...

  12. The impact of stellar feedback on the density and velocity structure of the interstellar medium

    OpenAIRE

    Grisdale, Kearn; Agertz, Oscar; Romeo, Alessandro B.; Renaud, Florent; Read, Justin I.

    2016-01-01

    We study the impact of stellar feedback in shaping the density and velocity structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry out $\\sim 4.6$pc resolution $N$-body+adaptive mesh refinement (AMR) hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way (MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the density and velocity structure of the interstellar medium using power spectra and compare the simulated galaxies to observed ...

  13. The Edgerton Structure: A Possible Meteorite Impact Feature in Eastern Kansas

    Directory of Open Access Journals (Sweden)

    Daniel F. Merriam

    2009-01-01

    Full Text Available Recognized meteorite impact features are relatively rare in the U.S. Midcontinent region, but recently with increased interest and research, the number has increased dramatically. We add another possibility to the growing list, the Edgerton structure in northwestern Miami County, Kansas. The feature is elliptical (∼5.5 × 6.5 km, slightly elongated east-west with radial surface drainage. The feature was first observed on hillshade maps of digitized topography of 7.5 minute quadrangles. Subsequent magnetic profiles show a higher magnetic value in the center of the ellipse with higher values around the edges; this shape is characteristic of an impact feature. Depth to the anomalous body is estimated to be about 1 km, which puts it in the Precambrian crystalline basement under a cover of Paleozoic sediments. There are no deep boreholes in the vicinity and no seismic profiles are available. If it is an impact structure, it will be the second such feature documented in Kansas, the first being the Brenham meteorite crater at Haviland in Kiowa County in southwestern Kansas. It would be older than the other impact structures identified in the Midcontinent—Manson in Iowa, Ames in Oklahoma, Haswell Hole in Colorado, and possibly Belton in Missouri and Merna in Nebraska. There are at least two other prospective impact features in Kansas: the Goddard ring west of Wichita and Garden City ellipse north-west of Garden City.

  14. Measurement of deforming mode of lattice truss structures under impact loading

    Directory of Open Access Journals (Sweden)

    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

  15. Numerical modeling of the formation and structure of the Orientale impact basin

    Science.gov (United States)

    Potter, Ross W. K.; Kring, David A.; Collins, Gareth S.; Kiefer, Walter S.; McGovern, Patrick J.

    2013-05-01

    The Orientale impact basin is the youngest and best-preserved lunar multi-ring basin and has, thus, been the focus of studies investigating basin-forming processes and final structures. A consensus about how multi-ring basins form, however, remains elusive. Here we numerically model the Orientale basin-forming impact with the aim of resolving some of the uncertainties associated with this basin. By using two thermal profiles estimating lunar conditions at the time of Orientale's formation and constraining the numerical models with crustal structures inferred from gravity data, we provide estimates for Orientale's impact energy (2-9 × 1025 J), impactor size (50-80 km diameter), transient crater size (˜320-480 km), excavation depth (40-55 km), and impact melt volume (˜106 km3). We also analyze the distribution and deformation of target material and compare our model results and Orientale observations with the Chicxulub crater to investigate similarities between these two impact structures.

  16. Conserving intertidal habitats: What is the potential of ecological engineering to mitigate impacts of coastal structures?

    Science.gov (United States)

    Perkins, Matthew J.; Ng, Terence P. T.; Dudgeon, David; Bonebrake, Timothy C.; Leung, Kenneth M. Y.

    2015-12-01

    Globally, coastlines are under pressure as coastal human population growth and urbanization continues, while climatic change leads to stormier seas and rising tides. These trends create a strong and sustained demand for land reclamation and infrastructure protection in coastal areas, requiring engineered coastal defence structures such as sea walls. Here, we review the nature of ecological impacts of coastal structures on intertidal ecosystems, seek to understand the extent to which ecological engineering can mitigate these impacts, and evaluate the effectiveness of mitigation as a tool to contribute to conservation of intertidal habitats. By so doing, we identify critical knowledge gaps to inform future research. Coastal structures alter important physical, chemical and biological processes of intertidal habitats, and strongly impact community structure, inter-habitat linkages and ecosystem services while also driving habitat loss. Such impacts occur diffusely across localised sites but scale to significant regional and global levels. Recent advances in ecological engineering have focused on developing habitat complexity on coastal structures to increase biodiversity. 'Soft' engineering options maximise habitat complexity through inclusion of natural materials, species and processes, while simultaneously delivering engineering objectives such as coastal protection. Soft options additionally sustain multiple services, providing greater economic benefits for society, and resilience to climatic change. Currently however, a lack of inclusion and economic undervaluation of intertidal ecosystem services may undermine best practice in coastline management. Importantly, reviewed evidence shows mitigation and even restoration do not support intertidal communities or processes equivalent to pre-disturbance conditions. Crucially, an absence of comprehensive empirical baseline biodiversity data, or data comprising additional ecological parameters such as ecosystem functions

  17. Continuous resistivity profiling and seismic-reflection data collected in April 2010 from Indian River Bay, Delaware

    Science.gov (United States)

    Cross, V.A.; Bratton, J.F.; Michael, H.A.; Kroeger, K.D.; Green, Adrian; Bergeron, Emile M.

    2014-01-01

    A geophysical survey to delineate the fresh-saline groundwater interface and associated sub-bottom sedimentary structures beneath Indian River Bay, Delaware, was carried out in April 2010. This included surveying at higher spatial resolution in the vicinity of a study site at Holts Landing, where intensive onshore and offshore studies were subsequently completed. The total length of continuous resistivity profiling (CRP) survey lines was 145 kilometers (km), with 36 km of chirp seismic lines surveyed around the perimeter of the bay. Medium-resolution CRP surveying was performed using a 50-meter streamer in a baywide grid. Results of the surveying and data inversion showed the presence of many buried paleochannels beneath Indian River Bay that generally extended perpendicular from the shoreline in areas of modern tributaries, tidal creeks, and marshes. An especially wide and deep paleochannel system was imaged in the southeastern part of the bay near White Creek. Many paleochannels also had high-resistivity anomalies corresponding to low-salinity groundwater plumes associated with them, likely due to the presence of fine-grained estuarine mud and peats in the channel fills that act as submarine confining units. Where present, these units allow plumes of low-salinity groundwater that was recharged onshore to move beyond the shoreline, creating a complex fresh-saline groundwater interface in the subsurface. The properties of this interface are important considerations in construction of accurate coastal groundwater flow models. These models are required to help predict how nutrient-rich groundwater, recharged in agricultural watersheds such as this one, makes its way into coastal bays and impacts surface-water quality and estuarine ecosystems.

  18. Fresh Water Inflow and Oyster Productivity in Apalachicola Bay, FL (USA)

    Science.gov (United States)

    Apalachicola Bay lies at the mouth of the Apalachicola River, where seasonally variable freshwater inflows and shifting winds support an unusually productive and commercially important oyster fishery. While there is concern that upstream water withdrawals may impact the fishery,...

  19. Nonindigenous Marine Species in Kaneohe Bay, Oahu, Hawaii in 1999-2000 (NODC Accession 0001053)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The presence and impact of nonindigenous (introduced) marine organisms in Kaneohe Bay, Oahu, Hawaiian Islands are evaluated using a combination of historical records...

  20. Nonindigenous marine species in Kaneohe Bay, Oahu, Hawaii in 1999 - 2000 (NODC Accession 0001053)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The presence and impact of nonindigenous (introduced) marine organisms in Kaneohe Bay, Oahu, Hawaiian Islands are evaluated using a combination of historical records...

  1. Nitrogen stable isotope ratios of anthropgenic organic matter in the coastal environment of Kosirina Bay (Murter Island, Croatia)

    Science.gov (United States)

    Dolenec, T.; Lambaša, Ž.; Lojen, S.; Rogan, N.; Kniewald, G.; Dolenec, M.

    2009-04-01

    In this study stable nitrogen isotopes ratios of particulate matter POM, zooplankton and selected biota such as Anemonia sulcata and Mytilus galloprovincialis were used to assessed the impact of anthropogenically derived organic matter from the untreated domestic sewage, municipal and industrial effluents on the coastal ecosystem of the Kosirina Bay (Murter Island). The differences in δ15N values observed in POM and organisms collected in Kosirina Bay as compared to POM and biota sampled at unaffected sites from the southern part of the Kornati Island and highly impacted Pirovac Bay revealed only a very minor effects of anthropogenic inputs of nutrients and organic matter which most probably derived from a sewage outfall south of the Tužbina Island. However, to get a better insight into the qualitative or quantitative shifts in the structure of aquatic food web caused by pollutants, more extended research on benthic population is needed, as well as a detailed investigation of seasonal variations of abundance and isotopic composition of POM and zooplankton as their presumed food source.

  2. A 3D, cross-scale, baroclinic model with implicit vertical transport for the Upper Chesapeake Bay and its tributaries

    Science.gov (United States)

    Ye, Fei; Zhang, Yinglong J.; Friedrichs, Marjorie A. M.; Wang, Harry V.; Irby, Isaac D.; Shen, Jian; Wang, Zhengui

    2016-11-01

    We develop a new vertically implicit transport solver, based on two total variation diminishing (TVD) limiters in space and time, inside a 3D unstructured-grid model (SCHISM), and apply it to the Upper Chesapeake Bay (UCB), which has complex geometry and sharp pycnocline. We show that the model is able to accurately and efficiently capture the elevation, velocity, salinity and temperature in both the deep and shallow regions of UCB. Compared with all available CTD casts, the overall model skills have the mean absolute error of 1.08 PSU and 0.85 °C, and correlation coefficient of 0.97 and 0.99 for salinity and temperature respectively. More importantly, the new implicit solver better captures the density stratification, which has great implications on biogeochemistry in this estuarine system. The cross-scale capability of the model is demonstrated by extending the high-resolution grids into a tributary (Chester River) and its sub-tributary (Corsica River), with minimal impact on the model efficiency. The model is also able to capture complex 3D structures at the transition zone between the main bay and the tributary, including the three-layered circulation in Baltimore Harbor. As more and more attention is being paid to the productive shallows in the Chesapeake Bay and other estuaries, the model can serve as a very powerful management tool to understand the impact of both local and remote forcing functions.

  3. Study on the Analytical Behaviour of Concrete Structure Against Local Impact of Hard Missile

    Directory of Open Access Journals (Sweden)

    Ahmad Mujahid Ahmad Zaidi

    2011-07-01

    Full Text Available Concrete is basic construction material used for almost all kind of structure. However, in the majority essential structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, highways barriers, bridges, & etc., concrete structures have to be designed as self-protective structure which can afford any disaster or consciously engendered unpleasant incidents such as incident occurs in nuclear plants, incident in any essential industry, terrorist attack, Natural disasters like tsunami and etc missile attack, and local impact damage generated by kinetic missiles dynamic loading (steel rods, steel pipes, turbine blades, etc.. This paper inquisitively is paying attention on verdict of the recent development in formulating analytical behavior of concrete and reinforced concrete structures against local impact effect generated by hard missile with and without the influence of dimensional analysis based on dominant non-dimensional parameters, various nose shape factors at normal and certain inclined oblique angles. The paper comprises the analytical models and methods for predicting penetration, and perforation of concrete and reinforced concrete. The fallout conquer from this study can be used for making design counsel and design procedures for seminal the dynamic retort of the concrete targets to foil local impact damage.

  4. Bird impact at aircraft structure - Damage analysis using Coupled Euler Lagrangian Approach

    Science.gov (United States)

    Smojver, I.; Ivancevic, D.

    2010-06-01

    Numerical bird strike damage prediction procedure has been applied on the very detailed large airplane secondary structure consisting of sandwich, composite and metallic structural items. The impacted inboard flap finite element model is modelled using 3D, shell and continuum shell elements, coupled with appropriate kinematic constraints. The bird has been modelled using Coupled Euler Lagrangian approach, in order to avoid the numerical difficulties connected with mesh distortion. Various failure modes, such as Carbon Fibre Reinforced Plastics (CFRP) face layer rupture, failure of composite matrix, damage initiation / evolution in the sandwich structure Nomex core and elastoplastic failure of a metallic structure have been investigated. Besides, general contact has been applied as to efficiently capture the contact between Eulerian bird material and the structure, as well as large deformations of the different structural components. Compared to the classic Lagrangian modelling of the bird, the analysis has proven to be more stable, and the results, such as damage areas, physically more realistic. The impact has been applied in the area that is the most probably subjected to the impact damage during exploitation.

  5. Impact Resistance of Lightweight Hybrid Structures for Gas Turbine Engine Fan Containment Applications

    Science.gov (United States)

    Hebsur, Mohan G.; Noebe, Ronald D.; Revilock, Duane M.

    2003-01-01

    The ballistic impact resistance of hybrid composite sandwich structures was evaluated with the ultimate goal of developing new materials or structures for potential gas turbine engine fan containment applications. The sandwich structures investigated consisted of GLARE-5 laminates as face sheets with lightweight cellular metallic materials such as honeycomb, foam, and lattice block as a core material. The impact resistance of these hybrid sandwich structures was compared to GLARE-5 laminates and 2024-T3 Al sheet, which were tested as a function of areal weight (material thickness). The GLARE-5 laminates exhibited comparable impact properties to that of 2024-T3 Al at low areal weights, even though there were significant differences in the static tensile properties of these materials. The GLARE-5, however, did have a greater ballistic limit than straight aluminum sheet at higher areal weights. Furthermore, there is up to a 25% advantage in ballistic limit for the GLARE-5/foam sandwich structures compared to straight 2024-T3 Al. But no advantage in ballistic limit was observed between any of the hybrid sandwich structures and thicker versions of GLARE-5. Recommendations for future work are provided, based on these preliminary data.

  6. Experimental study of wave impact on the nearshore structures during extreme coastal floods

    Science.gov (United States)

    Sriram, Venkatachalam; Didenkulova, Ira; Pelinovsky, Efim; Rodin, Artem; Didenkulov, Oleg; Sergeeva, Anna; Nair Vishnu, Reghunathan; Sundar, Vallam; Annamalaisamy Sannasiraj, Sannasi

    2016-04-01

    We study the dynamics of strongly nonlinear waves in the coastal zone and their impact on coasts during flash floods and tsunami. For this we use analytical theory of strongly nonlinear wave propagation along the slope and compare it with the data of experiments carried out in shallow water flume of IIT Madras (72 m long, 2 m wide and up to 2 m deep). Different kinds of waves like elongated solitons, N-waves are simulated and its run-up and impact force on the idealized structure on the slope are evaluated. Different numerical models (CLAWPACK, pseudospectral code for solving nonlinear evolutional equations and FNPT model) areused to describe strongly nonlinear waves along the slope. Results of numerical simulations are compared with predictions of analytical theory and with the data of experiments. The results presented here are the preliminary results obtained within DST - RFBR joint project "Impact of waterborne debris on the nearshore structures during extreme coastal floods".

  7. The Skin Picking Impact Scale: Factor structure, validity and development of a short version.

    Science.gov (United States)

    Snorrason, Ivar; Olafsson, Ragnar P; Flessner, Christopher A; Keuthen, Nancy J; Franklin, Martin E; Woods, Douglas W

    2013-08-01

    In the present study, we examined the psychometric properties of the Skin Picking Impact Scale (SPIS; Keuthen, Deckersbach, Wilhelm et al., 2001), a 10 item self-report questionnaire designed to assess the psychosocial impact of skin picking disorder (SPD). Participants were 650 individuals who met criteria for SPD in an online survey. Exploratory and confirmatory factor analyses demonstrated a unitary factor structure with high internal consistency (α = 0.94). Consequently, we constructed an abbreviated 4-item version that retained good internal consistency (α = 0.87) and a robust factor structure. Both the short and the full versions demonstrated discriminant and convergent/concurrent validity. In conclusion, the findings indicate that both versions are psychometrically sound measures of SPD related psychosocial impact; however, some potential limitations of the full scale are discussed.

  8. Elements of the Chicxulub Impact Structure as Revealed in SRTM and Surface GPS Topographic Data

    Science.gov (United States)

    Kinsland, Gary L.; Sanchez, Gary; Kobrick, Michael; Cardador, Manuel Hurtado

    2003-01-01

    Pope et al. [1] utilized the elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxulub Impact Structure is a roughly semi-circular, lowrelief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact, which possibly led to the development of these features. These are summarized in Table 1. Kinsland et al. [2] presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Very recently we have acquired digital topography data from NASA s Shuttle Radar Topography Mission (SRTM). Our subset covers 6 square degrees from 20deg N 91degW to 22deg N 88degW (corner to corner) with a pixel size of about 90m. This area includes all of the identified portion of the crater on land.

  9. Impacts of feeding strategy on microbial community structure diversity in vertical flow constructed wetlands

    Science.gov (United States)

    Jia, W. L.; Zhang, J.; Wang, Q.

    2016-08-01

    The impacts of feeding strategy (intermittently or continuously) on contaminant removal performance and microbial community structure in vertical flow constructed wetlands (VFCWs) were evaluated. The results showed that intermittent feeding strategy improved the removal of COD, TP and ammonium in VFCWs, although TN removal was weakened correspondingly The bacterial diversity decreased with the increase of substratum depth in all CWs. The intermittent feeding favored the growth of microorganisms due to the enhancement of oxygen content in the substratum. The feeding strategy had little impact on the microbial community in the surface substratum. However, in the bottom substratum, the impacts were of great significance. The microbial community structure similarity between the CWs with different feeding strategies was low.

  10. U/Pb Dating of Zircon from the Suvasvesi Impact Structures, Finland

    Science.gov (United States)

    Schwarz, W. H.; Breutmann, G.; Schmitt, A. K.; Trieloff, M.; Ludwig, T.; Hanel, M.; Buchner, E.; Schmieder, M.; Pesonen, L. J.; Moilanen, J.

    2016-08-01

    The two Suvasvesi impact structures (Finland), both covered by lakes, forming an apparent crater doublet, were analysed by in-situ U/Pb dating of zircon grains, concluding that the two craters were formed in separate events, ~600 Ma apart.

  11. The Structure at Sierra Ambato, Catamarca, Argentina: A New Meteorite Impact Site?

    Science.gov (United States)

    Acevedo, R. D.; Rocca, M.; Alonso, R.; Rabassa, J.; Ponce, J. F.

    2012-09-01

    A new possible impact crater was discovered in Catamarca Province: the structure at Sierra Ambato (28º 03" 23.22” S, 66º 03" 11.06” W), located at Sierras Pampeanas (3,500 m.a.s.l). It has 1.0 km in diameter.

  12. The impact of powder diffraction on the structural characterization of organic crystalline materials.

    Science.gov (United States)

    Tremayne, Maryjane

    2004-12-15

    The bulk properties of organic crystalline materials depend on their molecular and crystal structures but, as many of these materials cannot be prepared in a suitable form for conventional single-crystal diffraction studies, structural characterization and rationalization of these properties must be obtained from powder diffraction data. The recent development of direct-space structure solution methods has enabled the study of a wide range of organic materials using powder diffraction data, many of structural complexity only made tractable by these advances in methodology. These direct-space methods are based on a number of global optimization techniques including Monte Carlo, simulated annealing, genetic algorithm and differential evolution approaches. In this article, the implementation and relative efficiency and reliability of these methods are discussed, and their impact on the structural study of organic materials is illustrated by examples of polymorphic systems, pharmaceutical, pigment and polypeptide structures and compounds used in the study of intermolecular networks.

  13. The Bayes Inference Engine

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, K.M.; Cunningham, G.S.

    1996-04-01

    The authors are developing a computer application, called the Bayes Inference Engine, to provide the means to make inferences about models of physical reality within a Bayesian framework. The construction of complex nonlinear models is achieved by a fully object-oriented design. The models are represented by a data-flow diagram that may be manipulated by the analyst through a graphical programming environment. Maximum a posteriori solutions are achieved using a general, gradient-based optimization algorithm. The application incorporates a new technique of estimating and visualizing the uncertainties in specific aspects of the model.

  14. Corpus Christi, Nueces, and Aransas Bays

    Science.gov (United States)

    Handley, Lawrence R.; Spear, Kathryn A.; Eleonor Taylor,; Thatcher, Cindy

    2015-01-01

    Corpus Christi Bay and Nueces Bay comprise the middle estuarine portion of Texas’ Coastal Bend region (Figure 1; Burgan and Engle, 2006). Aransas Bay is part of the upper estuarine portion of the region. These bays make up part of the Coastal Bend Bays and Estuaries Program, one of the many estuarine areas in the U.S. Environmental Protection Agency’s National Estuary Program (Holt, 1998). The Coastal Bend region is sub-humid and sub-tropical. Summers are long, hot, and humid, and winters are short and mild. The landscape around the estuaries is dominated by row crops, pastures, and brushy rangeland (Handley and others, 2007). The Nueces River, along with other smaller rivers and creeks, provides freshwater inflow—along with essential nutrients and sediment— into Nueces Bay, which feeds into Corpus Christi Bay (Holt, 1998). Freshwater inflow into the Aransas Bay comes from Mission River, Aransas River, and Copano Creek. The region is relatively dry otherwise and prone to droughts. Corpus Christi receives an average of 76.2 cm (30 in) of rain annually; evaporation usually exceeds 177.8 cm (70 in) (Holt, 1998; Handley and others, 2007). The San Antonio-Nueces Coastal Basin drains into Aransas Bay. The Nueces River basin covers 43,253 km2 (16,700 miles2 ), from northwest of San Antonio, flowing southeast to where it drains into Nueces and Corpus Christi Bays (Holt, 1998). The Nueces-Rio Grande basin covers approximately 18,648 1 U.S. Geological Survey National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, LA 70506 2 Harte Research Institute for Gulf of Mexico Studies, Texas A&M University - Corpus Christi, 6300 Ocean Drive, Unit 5869, Corpus Christi, Texas 78412 2 km2 (7,200 miles2 ) and flows partially into Corpus Christi Bay (as well as the upper Laguna Madre). The inflow from Nueces River has declined by approximately 20 percent over the past several decades, partly due to construction of lakes and reservoirs, particularly Lake Corpus Christi

  15. Deterministic modeling of the impact of underground structures on urban groundwater temperature.

    Science.gov (United States)

    Attard, Guillaume; Rossier, Yvan; Winiarski, Thierry; Eisenlohr, Laurent

    2016-12-01

    Underground structures have a major influence on groundwater temperature and have a major contribution on the anthropogenic heat fluxes into urban aquifers. Groundwater temperature is crucial for resource management as it can provide operational sustainability indicators for groundwater quality and geothermal energy. Here, a three dimensional heat transport modeling approach was conducted to quantify the thermally affected zone (TAZ, i.e. increase in temperature of more than +0.5°C) caused by two common underground structures: (1) an impervious structure and (2) a draining structure. These design techniques consist in (1) ballasting the underground structure in order to resist hydrostatic pressure, or (2) draining the groundwater under the structure in order to remove the hydrostatic pressure. The volume of the TAZ caused by these underground structures was shown to range from 14 to 20 times the volume of the underground structure. Additionally, the cumulative impact of underground structures was assessed under average thermal conditions at the scale of the greater Lyon area (France). The heat island effect caused by underground structures was highlighted in the business center of the city. Increase in temperature of more than +4.5°C were locally put in evidence. The annual heat flow from underground structures to the urban aquifer was computed deterministically and represents 4.5GW·h. Considering these impacts, the TAZ of deep underground structures should be taken into account in the geothermal potential mapping. Finally, the amount of heat energy provided should be used as an indicator of heating potential in these areas.

  16. 75 FR 29891 - Special Local Regulation; Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay...

    Science.gov (United States)

    2010-05-28

    ... Swim, Great South Bay, NY, in the Federal Register (74 FR 32428). We did not receive any comments or... published at 74 FR 32428 on July 8, 2009, is adopted as a final rule with the following changes: PART 100... South Bay Cross Bay Swim, Great South Bay, NY AGENCY: Coast Guard, DHS. ACTION: Final rule. SUMMARY:...

  17. Contribution to the modelling and simulation of aircraft structures impacting on water

    OpenAIRE

    Toso, Nathalie Renée Solange

    2009-01-01

    The impact on water of aeronautical structures is of concern as soon as an aircraft is designed to operate over sea. For the need of the ditching certification, it can be summarised that the structure should be able to land on water and float long enough to enable the passengers and crew members to evacuate. Until the middle of the 90's, compliance to the regulations was mainly shown by tests performed in a basin using a mock-up structure completed by relative simple theoretical evaluations o...

  18. Structural Changes of International Trade Flows under the Impact of Globalization

    Directory of Open Access Journals (Sweden)

    Anca Dachin

    2006-08-01

    Full Text Available Structural changes of international trade flows indicate modifications in competitiveness of countries, in terms of production, technological upgrading and exports under the pressure of globalization. The paper aims to point out sources of competitive advantages especially in manufacturing exports of different groups of countries. The focus is on the shifts in the structure of manufacturing in the European Union and their effects on international rankings in export performances. An important issue refers to the opportunities given by the enlargement of the European Union and their impact on EU trade structures.

  19. A Creek to Bay Biological Assessment in Oakland, California

    Science.gov (United States)

    Ahumada, E.; Ramirez, N.; Lopez, A.; Avila, M.; Ramirez, J.; Arroyo, D.; Bracho, H.; Casanova, A.; Pierson, E.

    2011-12-01

    In 2007, the Surface Water Ambient Monitoring Program (SWAMP) assessed the impact of trash on water quality in the Peralta Creek which is located in the Fruitvale district of Oakland, CA. This 2011 follow-up study will take further steps in evaluating the physical and biological impacts of pollution and human development on Peralta Creek and in the San Leandro Bay, where the Creek empties into the larger San Francisco Bay estuary. This study will utilize two forms of biological assessment in order to determine the level of water quality and ecosystem health of Peralta Creek and San Leandro Bay in Oakland, California. A Rapid Bioassesment Protocal (RBP) will be used as the method of biological assessment for Peralta Creek. RBP uses a biotic index of benthic macroinvertebrates to provide a measure of a water body's health. Larval trematodes found in two mud snails (Ilynassa obsoleta and Cerithidea californica) will be used to evaluate the health of the San Leandro Bay. Due to the complex life cycle of trematodes, the measure of trematode diversity and richness in host species serves as an indicator of estuarine health (Huspeni 2005). We have completed the assessment of one section of Peralta Creek, located at 2465 34th Avenue, Oakland, CA 94601. Abundance results indicate a moderately healthy creek because there were high levels of pollution tolerant benthic macroinvertebrates. The tolerant group of benthic macroinvertebrates includes such organisms as flatworms, leeches, and scuds. This is possibly due to this section of the creek being pumped up to the surface from culverts impacting the macroinvertebrate's life cycle. Another contributing factor to creek health is the amount of organic debris found in the creek, which inhibits the flow and oxygenation of the water, allowing for more pollution tolerant aquatic insects to persist. Further investigation is being conducted to fully assess the Peralta Creek watershed; from the preliminary results one can surmise that

  20. The impact of ligands on the structure and flexibility of sulfotransferases: a molecular dynamics simulation study.

    Science.gov (United States)

    Zhao, Li; Zhang, Pupu; Long, Shiyang; Wang, Linlin; Tian, Pu

    2015-08-01

    Sulfotransferases catalyze transfer of the sulfuryl-group (-SO3) from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to a large number of substrates. They play an important role in phase II metabolic process. The impact of the cofactor (PAPS) on the structure and flexibility of the enzyme has been studied extensively, and the response of the active-cap region to cofactor binding was proposed as the molecular basis for substrate selectivity. In this study, individual and cooperative effects of the cofactor and substrate on the structure and flexibility of the enzyme were investigated. Molecular dynamics simulations were performed for four systems, including free enzyme, binary complexes (cofactor or substrate bound enzyme) and ternary complex (both cofactor and substrate bound enzyme). The influence of ligands (the cofactor and the substrate) on the structure and flexibility of the enzyme, especially that of the active-site cap region, was analyzed. Moreover, mutual structural impact of the ligands was examined as well. The results show that the impact of both the cofactor and the substrate was significant. Our study indicated that the substrate, such as lithocholic acid (LCA), participated in regulating the structure and flexibility of the enzyme actively rather than merely being selected passively. Additionally, the observed synergistic effects of the cofactor and the substrate demonstrated the importance of examining both ligands in understanding enzymes.

  1. Crushable Structure for the Landing Impact of a European Mars Exploration Mission (ExoMars 2016)

    Science.gov (United States)

    del Campo, F.; Bernar, E.; Biondetti, G.; Jauregui, Y. E.; Walloschek, T.

    2012-07-01

    The first mission of the ExoMars programme, scheduled to arrive at Mars in 2016, includes an Entry, Descent and Landing Demonstrator Module (EDM). One of the EDM objectives is to demonstrate the possibility to safely absorb the landing impact by means of a deformable structure placed under the Surface Platform (SP), the EDM sub-module reaching ground. This is one of the key technologies in preparation for ESA's contribution to subsequent missions to Mars. SENER is responsible for several structures and mechanisms for the EDM, with TAS-I as Prime contractor. The paper focuses on the Crushable Structure, which is the main element affected by the impact. Its function is to absorb the landing impact after thruster switch off at around 2 meters over the Martian surface, allowing a safe landing for the equipments in terms of acceleration levels, and for the whole structure in terms of stability and non-overturning. An optimized structure has been designed for this purpose, within a restricted envelope, able to meet these requirements for a wide range of terrain configurations, including rocks and slopes.

  2. Analysis on Impact Factors of Water Utilization Structure in Tianjin, China

    Directory of Open Access Journals (Sweden)

    Conglin Zhang

    2016-03-01

    Full Text Available Water is an essential foundation for socio-economic development and environmental protection. As such, it is very critical for a city’s sustainable development. This study analyzed the changes in water utilization structure and its impact factors using water consumption data for agricultural, industrial, domestic and ecological areas in the city of Tianjin, China from 2004 to 2013. On this base, the evolution law and impact factors of water utilization structure were depicted by information entropy and grey correlation respectively. These analyses lead to three main results. First, the total amount of water consumption in Tianjin increased slightly from 2004 to 2013. Second, the information entropy and equilibrium degree peaked in 2010. From 2004 to 2010, the water utilization structure tended to be more disordered and balanced. Third, the economic and social factors seemed to influence the water utilization structure, while the main impact factors were industrial structure, per capita green area, cultivated area, effective irrigation area, rural electricity consumption, animal husbandry output, resident population, per capita domestic water etc.

  3. Faunal impact on vegetation structure and ecosystem function in mangrove forests: A review

    DEFF Research Database (Denmark)

    Cannicci, S.; Burows, D.; Fratini, S.

    2008-01-01

    The last 20 years witnessed a real paradigm shift concerning the impact of biotic factors on ecosystem functions as well as on vegetation structure of mangrove forests. Before this small scientific revolution took place, structural aspects of mangrove forests were viewed to be the result of abiotic...... to be considered a main actor in mangrove structuring processes, thanks to a number of studies carried out in the Indo-Pacific forests in the late 1970s and early 1980s. Following these classical papers, a number of studies on Sesarmidae feeding and burrowing ecology were carried out, which leave no doubts about...... that older techniques used to assess herbivory rates by insects strongly underestimate their impact, both in case of leaf eating and wood boring species and that herbivorous insects can potentially play a strong role in many aspects of mangrove ecology. Moreover, researchers only recently realized that ant...

  4. Faunal impact on vegetation structure and ecosystem function in mangrove forests

    DEFF Research Database (Denmark)

    Cannicci, S.; Burrows, Damien; Fratini, Sara

    2008-01-01

    The last 20 years witnessed a real paradigm shift concerning the impact of biotic factors on ecosystem functions as well as on vegetation structure of mangrove forests. Before this small scientific revolution took place, structural aspects of mangrove forests were viewed to be the result of abiotic...... to be considered a main actor in mangrove structuring processes, thanks to a number of studies carried out in the Indo-Pacific forests in the late 1970s and early 1980s. Following these classical papers, a number of studies on Sesarmidae feeding and burrowing ecology were carried out, which leave no doubts about...... that older techniques used to assess herbivory rates by insects strongly underestimate their impact, both in case of leaf eating and wood boring species and that herbivorous insects can potentially play a strong role in many aspects of mangrove ecology. Moreover, researchers only recently realized that ant...

  5. Chicxulub impact basin: Gravity characteristics and implications for basin morphology and deep structure

    Science.gov (United States)

    Sharpton, Virgil L.; Burke, Kevin; Hall, Stuart A.; Lee, Scott; Marin, Luis E.; Suarez, Gerardo; Quezada-Muneton, Juan Manuel; Urrutia-Fucugauchi, Jaime

    1993-01-01

    The K-T-aged Chicxulub Impact Structure is buried beneath the Tertiary carbonate rocks of the Northern Yucatan Platform. Consequently its morphology and structure are poorly understood. Reprocessed Bouguer (onshore) and Free Air (offshore) gravity data over Northern Yucatan reveal that Chicxulub may be a 200-km-diameter multi-ring impact basin with at least three concentric basin rings. The positions of these rings follow the square root of 2 spacing rule derived empirically from analysis of multi-ring basins on other planets indicating that these rings probably correspond to now-buried topographic basin rings. A forward model of the gravity data along a radial transect from the southwest margin of the structure indicates that the Chicxulub gravity signature is compatible with this interpretation. We estimate the basin rim diameter to be 204 +/- 16 km and the central peak ring diameter (D) is 104 +/- 6 km.

  6. The Structures of Sediment Microbial Communities in Different Mariculture Models at Xiangshan Bay of China%象山港南沙岛不同养殖模式沉积物微生物群落结构分析

    Institute of Scientific and Technical Information of China (English)

    孙超; 朱玲; 毛玉泽; 范艳君; 周春娅; 杨傲傲; 朱伟; 庄志猛

    2014-01-01

    通过构建16S rDNA克隆文库对象山港南沙岛不同养殖模式(贝类养殖、藻类养殖及网箱养殖)表层沉积物微生物多样性和群落结构特征进行了比较和分析,共获取136个OUT。其中,贝类养殖区、藻类养殖区和网箱养殖区OTU分别为58、48和57个。各站位OTU分布差异明显,表现出高度的多样性。基于16S rDNA序列的生物多样性和丰富度分析表明,网箱养殖区丰富度指数ACE为739,香浓指数H¢为3.8,均为最高值,丰富度指数Chao为245,略低于于贝类养殖区。贝类养殖区丰富度指数Chao为303,在各养殖区中最高。藻类养殖区丰富度指数ACE为174、Chao为89,香浓指数H¢为3.6,均为最低值。系统发育分析表明,南沙岛各养殖区的优势种群均为变形菌门(Proteobacteria),但是藻类养殖区微生物群落结构与其他养殖区域相比,16S rDNA克隆文库差异显著,其中根瘤菌属(Rhizobium)及其他光合细菌在藻类养殖区分布较多。网箱养殖区沉积物表层微生物群落中出现了与环境污染密切相关的菌群,如志贺氏菌属(Shigella)、埃希氏菌属(Escherichia)和ε-变形菌纲的微生物种群,揭示网箱养殖对底质沉积物环境的影响较大。%Xiangshan Bay, the biggest marine aquaculture base in Zhejiang Province, is a semi- enclosed bay with slow water exchange rate. In the center of Xiangshan Bay lies Nansha Bay where a variety of mariculture models are applied. To better understand the structures and diversity of sediment microbial communities in different mariculture models, we constructed the 16S rDNA clone library for the analysis of samples from the shellfish culture, the seaweed culture and the fish cage culture. We obtained 136 OTUs from three sampling models that included 58 OTUs from the shellfish culture, 48 from the seaweed culture, and 57 from the fish cage culture. The distribution patterns of OTUs were highly different

  7. Geophysical characterization of circular structures in Chubut and Mendoza (Argentina): Impact vs. Volcanism

    Science.gov (United States)

    Prezzi, C.; Orgeira, M. J.; Risso, C.; Acevedo, R.; Ponce, F.; Nullo, F.; Martinez, O.; Rabassa, J.; Margonari, L.; Corbella, H.

    2013-05-01

    This work focuses on two main objectives. One of them is to provide information to discern the genesis of the circular structures present in Bajada del Diablo (Chubut, Argentina) considered as impact craters, and the other one is to contribute to a better knowledge of the circular structures located in the volcanic fields of Llancanelo and Payunia (Mendoza, Argentina). Chubut circular structures have been attributed to the collision of an extraterrestrial body, possibly an asteroid. However, doubts persist about their genesis because of the lack of direct geological evidences. Since detailed geomorphological studies have ruled out an origin by wind deflation, the prevailing alternative hypothesis attributes these circular structures to a volcanic process. On the other hand, the study of the volcanic fields of Payunia and Llancanelo (Mendoza) will contribute to the knowledge of the mechanics of hydromagmatic processes in the area, and the origin of circular structures morphologically similar to those located in Chubut. In the Payunia volcanic field at least 27 cones with evidences of hydromagmatism, in a field of more than 800 pure magmatic cones, have been recognized. This study tries to determine if a relationship between the observed volcanic circular structures and participation of water during the eruption exists. Magnetic and gravity field surveys of the circular volcanic structures in Llancanelo and Payunia volcanic fields were performed in order to determine their relationship with the type of eruption. Electromagnetic, magnetic and gravity field surveys were also carried out in Chubut circular structures. The comparative analysis of geological and geophysical results obtained in the circular structures of Chubut and those obtained in the circular structures in the volcanic areas of Llancanelo and Payunia suggest an impact origin for the circular structures of Chubut.

  8. The mediterranean coast of Andalusia (sw spain): the impacts of human coastal structures

    Science.gov (United States)

    Liguori, Vincenzo; Manno, Giorgio; Messina, Enrica; Anfuso, Giorgio; Suffo, Miguel

    2015-04-01

    Spanish coasts, especially the Andalusia Mediterranean one, were affected over time by progressive urbanization and associated construction of defense structures. Such structures protected small coastal sectors but at places triggered processes of coastal erosion and associated degradation of habitats and ecosystems. A correct management of coastal areas must be based on the monitoring of coastal evolution and human pressure. A useful tool to evaluate the level of human anthropization is the estimation of the "Coastal Armouring", e.g. the quantification of coastal defense structures, infrastructures, ports, etc. In this study, available aerial photographs and satellite images from 1956 to 2011 were scanned and geo-referenced and used for the quantitative assessment of coastal human constructions impact on the studied coastal area. The so called coefficient of technogenous impact (K) was used. It results from the relationship between the total length of all maritime structures (groins, moles, seawalls, dikes, channels, etc.) and the entire length of the study coastal section. For this purpose, the Andalusia coast, about 500 km in length, was divided into sections of 1 km. For each one of such sections the technogenous impact was calculated in the 1956 and 2011 documents. The analysis showed that the degree of anthropization in some areas (for example the Port of Montril) has increased considerably, triggering degradation processes in the nearby coastal areas. Results also evidenced as, in many cases, greatest human impacts are linked to the progressive construction of coastal defense. The lack of a general strategy to combat the erosion problem and the urgency in the short term to protect specific parts of the coast led to a reactive approach based initially in the construction of hard structures. Such interventions locally solved erosion problems but gave rise to drowndrift erosion according to the "domino" effect. A more general management plan is needed

  9. Pronounced central uplift identified in the Bosumtwi impact structure, Ghana, using multichannel seismic reflection data

    Science.gov (United States)

    Scholz, Christopher A.; Karp, Tobias; Brooks, Keely M.; Milkereit, Bernd; Amoako, Philip Y. O.; Arko, Justice A.

    2002-10-01

    The Lake Bosumtwi impact structure is the youngest and best-preserved complex terrestrial impact crater and serves as an important reference site for the study of cratering processes. Because the impacting body struck continental crystalline target rocks and not a submerged sedimentary platform, no significant backwash processes have modified the crater morphology. Not only may Bosumtwi contain the best-preserved central uplift structure on Earth, but it is the most accessible relatively large, young crater in the solar system generated in a large gravity field. There is a well-established link between the Lake Bosumtwi impact structure and the Ivory Coast tektite field, and the lacustrine sediments within the crater contain a unique 1 m.y. record of paleoclimate in the continental tropics south of the Sahel. Eight profiles of marine-type multichannel seismic reflection (MCS) data were acquired from the 8-km-diameter, ˜75-m-deep lake that fills much of the crater. These were augmented by wide-angle seismic data acquired with ocean-bottom hydrophones. MCS data reveal a well-defined central uplift near the northwest-central part of the lake and a maximum postimpact lacustrine sediment thickness of ˜310 m. The central uplift structure has a diameter of 1.9 km and a maximum height of 130 m above the annular moat inside the crater. An intermediate velocity layer (3200 m/s) beneath the lacustrine sediment is interpreted as fallback breccia or a breccia-melt horizon. The measured apparent depth of the crater (da) is 500 m, implying a slightly higher aspect ratio for the structure than predicted from published empirical relationships. The Bosumtwi structure is a small complex crater that deviates slightly from trends predicted from classical scaling laws, perhaps because of the effects of a large gravity field.

  10. Evaluation of the Impact of the EU Structural Support on the Competitiveness of Lithuanian Economics

    Directory of Open Access Journals (Sweden)

    Remeikiene Rita

    2016-05-01

    Full Text Available The topic of competitiveness is becoming increasingly significant in the context of modern economics. Considering intensive processes of globalisation alongside with competitive pressure amongst the countries, competitiveness has become a necessary condition for successful economic and social development of any country. Only by creating, enforcing and maintaining international competitiveness of the country, rapid economic growth during the long term is achievable. Amongst the other urgent issues, the European Union (further the EU public policies are also focused on competitiveness. After the failure to implement the Lisbon strategy and become “the most dynamic and competitive knowledge-based economy”, the EU declared its new competitiveness aims in the long-term strategy Europe 2020. Promotion of competitiveness is one of the fundamental aims and priority directions of the EU structural policy. The EU structural support is engaged as one of the public policy measures to promote the competitiveness of the member-states. In this context, it is purposeful to research whether the structural support is used efficiently and whether it actually contributes to the implementation of the defined aims. Under the order of various Lithuanian institutions, numerous studies on the efficiency of the EU structural support have been carried out. Nevertheless, by analysing the impact of the EU structural support, insufficient attention has been paid to the aspect of competitiveness. Considering the fact that Lithuania has entered the third programming period 2014-2020, evaluation of the EU structural investment in the country has become even more topical - for successful implementation of the aims raised for this new period, the analysis of the previous results is relevant. This determined formulation of the research problem: what impact does the EU structural support have on the competitiveness of Lithuanian economics? The empirical research has revealed

  11. 引水放流方式对太湖贡湖示范区水质的影响%Impact of Water Diversion Methods on Water Quality of the Demonstration Area in Gonghu Bay

    Institute of Scientific and Technical Information of China (English)

    杨阳; 钱新; 叶瑞; 高海龙; 刘喆

    2015-01-01

    A proportional physical model,in accordance with the demonstration area which locates in Gonghu Bay,Taihu Lake,was constructed to meet the demand of controlling both quality and quantity of water within that area for the state water special project.The effects of four diversion methods in the models would be studied in or-der to provide arguments for making decisions between diversion methods for the demonstration area.When con-ducting the study,the influences to the model′s flow field,assessed by measuring flow field data at five different cross sections,would be deemed as indicators for evaluating different diversion methods.Meanwhile,ink was cho-sen as a tracer and the spreading field changes of the tracer caused by different diversion methods would verify conclusions to the flow field.Therefore,an analysis could be conducted for the impact to water quality caused by the methods.The study provided a helpful reference for deciding the diversion method for the demonstration area.%基于国家水专项太湖贡湖湾示范区水质水量调控的需求,构建了示范区的等比例缩放实体模型。通过研究模型中4种不同调水方案的效果,为示范区调水技术的比较与选择提供决策依据。研究中,通过测定模型中5个断面的流场数据,判断引水方式对模型流场的影响,以此评价不同调水方案效果。同时以墨汁作为示踪剂,通过不同引水放流方式下示踪剂的扩散场变化,验证不同断面流速测定对整个区域流场判断的准确性,从而分析引水放流方式对水质的影响。

  12. Experimental and Numerical Investigation of Wide Area Blunt Impact Damage to Composite Aircraft Structures

    Science.gov (United States)

    Chen, Zhi Ming

    Due to their high performance and weight efficiency, carbon fiber composites are increasingly being used in aircraft primary structure applications. Exposed composite structures (e.g., fuselage lower body) are susceptible accidental impacts by ground service equipment (GSE). The very high mass (over 10,000 kg) of GSE impact can involve high energy (over 1000 J) and thus can induce significant internal damage. Furthermore, the large contact area potentially involved with GSE impact can create significant internal delamination and fiber failure without leaving exterior-visible signs that any damage has occurred. The objectives of the research described herein are to: (1) conduct experimental investigation into the composite aircraft damage caused by GSE impact, (2) examine the small-scale failure modes in focused, element-level studies, (3) establish a finite element modeling methodology involving detailed simulation capability that is validated via small-scale tests, and (4) apply these modeling capabilities to accurately predict full-scale structural behavior without adjustment (e.g., tuning) of modeling input parameters.

  13. Micro-structural strengthening mechanism of multiple laser shock processing impacts on AISI 8620 steel

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Zhong, J.W., E-mail: zjw1033@126.com [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Luo, K.Y.; Zhang, L.; Dai, F.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Chen, K.M. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Q.W.; Zhong, J.S.; Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China)

    2011-07-25

    Highlights: {yields} LSP can clearly refine coarse grains in the shocked region by dislocation movement. {yields} Micro-structural evolution of AISI 8620 steel after LSP impacts is revealed. {yields} LSP on AISI 8620 steel have grain refinement and dispersion strengthening of carbon. {yields} The results can provide some insights on surface modification of low carbon steel. - Abstract: Micro-structural evolution in the near-surface region of AISI 8620 steel subjected to multiple laser shock processing (LSP) impacts were investigated by means of cross-sectional optical microscopy (OM) and transmission electron microscopy (TEM) observations. Micro-structural evolution process subjected to multiple LSP impacts can be described as follows: (i) the parallel lamellar pearlites are broken into bitty pearlites, and dislocation activities simultaneously led to the formation of dislocation lines (DLs) and dislocation pile-ups in original grains; (ii) bitty pearlites were all broken into Fe{sub 3}C granules, and dislocation movement made Fe{sub 3}C granules disperse near subgrain boundaries and led to subgrain boundaries separating individual cells, and (iii) subgrain boundaries were refined to grain boundaries. Multiple LSP impacts on AISI 8620 steel had dual-function: the refinement of coarse grains in the near-surface region by dislocation movement and dispersion strengthening of C atoms which cut cementite and diffused into the ferrite by moving dislocations.

  14. Oceanic Impact: Mechanisms and Environmental Perturbations

    Science.gov (United States)

    Gersonde, Rainer (Editor); Deutsch, Alex (Editor); Ivanov, Boris A. (Editor); Kyte, Frank T. (Editor)

    2002-01-01

    The contents include the following: Oceanic impacts-a growing field of fundamental geoscience. Shock metamorphism on the ocean floor (numerical simulations). Numerical modeling of impact-induced modifications of the deep-sea floor. Computer modelling of the water resurge at a marine impact: the Lockne crater, Sweden. Experimental investigation of the role of water in impact vaporization chemistry. Calcareous plankton stratigraphy around the Pliocene Eltanin asteroid impact area (SE Pacific): documentation and application for geological and paleoceanographic reconstruction. Composition of impact melt debris from the Eltanin impact strewn field, Bellingshausen Sea. Iridium concentrations and abundances of meteoritic ejecta from the Eltanin impact in sediment cores from Polarstern expedition ANT XII/4. Unmelted meteoritic debris collected from Eltanin ejecta in Polarstern cores from expedition ANT XII/4. Impact tsunami-Eltanin. Ancient impact structures on modern continental shelves: The Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin of North America. The Mjolnir marine impact crater porosity anomaly. Kardla (Hiiu-maa Island, Estonia) - the buried and well-preserved Ordovician marine impact structure. Long-term effect of the Kardla crater (Hiiu-maa, Estonia) on Late Ordovician carbonate sedimentation. The middle Devonian Kaluga impact crater (Russia): new interpretation of marine setting.

  15. Inventory of rock avalanches in western Glacier Bay National Park and Preserve, Alaska, 1984-2016: a baseline data set for evaluating the impact of climate change on avalanche magnitude, mobility, and frequency

    Science.gov (United States)

    Bessette-Kirton, Erin; Coe, Jeffrey A.

    2016-01-01

    The effects of climate change have the potential to impact slope stability. Negative impacts are expected to be greatest at high northerly latitudes where degradation of permafrost in rock and soil, debuttressing of slopes as a result of glacial retreat, and changes in ocean ice-cover are likely to increase the susceptibility of slopes to landslides. In the United States, the greatest increases in air temperature and precipitation are expected to occur in Alaska. In order to assess the impact that these environmental changes will have on landslide size (magnitude), mobility, and frequency, inventories of historical landslides are needed. These inventories provide baseline data that can be used to identify changes in historical and future landslide magnitude, mobility, and frequency.  This data release presents GIS and attribute data for an inventory of rock avalanches in a 5000 km2 area of western Glacier Bay National Park and Preserve, Alaska. We created the inventory from 30 m resolution Landsat imagery acquired from June 1984 to September 2016.  For each calendar year, we visually examined a minimum of one Landsat image obtained between the months of May and October. We examined a total of 104 Landsat images. The contrast between the spectral signatures of freshly exposed rock avalanche source areas and deposits and surrounding undisturbed snow and ice was typically significant enough to detect surficial changes. We identified and mapped rock avalanches by locating areas with 1) high contrast compared to surrounding snow and ice, 2) different spectral signatures between successive Landsat images, and 3) lobate forms typical of rock-avalanche deposits. Using these criteria, we mapped a total of 24 rock avalanches ranging in size from 0.1 to 22 km2.Attribute data for each rock avalanche includes: a date, or range in possible dates, of occurrence; the name of the Landsat image(s) used to identify and map the avalanche; the total area covered by the rock avalanche

  16. A modified Kelvin impact model for pounding simulation of base-isolated building with adjacent structures

    Institute of Scientific and Technical Information of China (English)

    Ye Kun; Li Li; Zhu Hongping

    2009-01-01

    Base isolation can effectively reduce the seismic forces on a superstructure, particularly in low- to medium-rise buildings. However, under strong near-fault ground motions, pounding may occur at the isolation level between the base-isolated building (BIB) and its surrounding retaining walls. To effectively investigate the behavior of the BIB pounding with adjacent structures, after assessing some commonly used impact models, a modified Kelvin impact model is proposed in this paper. Relevant parameters in the modified Kelvin model are theoretically derived and numerically verified through a simple pounding case. At the same time, inelasticity of the isolated superstructure is introduced in order to accurately evaluate the potential damage to the superstructure caused by the pounding of the BIB with adjacent structures. The reliability of the modified Kelvin impact model is validated through numerical comparisons with other impact models. However, the difference between the numerical results from the various impact analytical models is not significant. Many numerical simulations of BIBs are conducted to investigate the influence of various design parameters and conditions on the peak inter-story drills and floor accelerations during pounding. It is shown that pounding can substantially increase floor accelerations, especially at the ground floor where impacts occur. Higher modes of vibration are excited during poundings, increasing the inter-story drifts instead of keeping a nearly rigid-body motion of the superstructure. Furthermore, higher ductility demands can be imposed on lower floors of the superstructure. Moreover, impact stiffness seems to play a significant role in the acceleration response at the isolation level and the inter-story drifts of lower floors of the superstructure. Finally, the numerical results show that excessive flexibility of the isolation system used to minimize the floor accelerations may cause the BIB to be more susceptible to pounding

  17. Projectiles Impact Assessment of Aircraft Wing Structures with Real Dynamic Load

    Science.gov (United States)

    Han, Lu; Han, Qing; Wang, Changlin

    2015-07-01

    This paper presents an analysis to achieve the impact damage of the wing structure under real dynamic load. MPCCI tools are utilized to convert wing aerodynamic load into structural Finite Element Method (FEM) node load. The ANSYS/LS-DYNA code is also used to simulate the dynamic loading effects of the wing structure hit by several projectiles, including both active damage mechanism and common damage mechanism. In addition, structural node force on the leading edge and the midline is compared to the aerodynamic load separately. Furthermore, the statistical analysis of the penetrating size and the stress concentration around the damage holes indicates that under the same load situation, the structural damage efficiency of active damage mechanism is significantly higher than the one of common damage mechanism.

  18. Sediment distribution modeling for evaluating the impact of initial structure on catchment hydrological behaviour

    Science.gov (United States)

    Maurer, T. J.; Gerke, H. H.; Hinz, C.

    2015-12-01

    Structural heterogeneity, namely the spatial distribution of soils and sediments (represented by mineral particles), characterizes catchment hydrological behavior. In natural catchments, local geology and the specific geomorphic processes determine the characteristics and spatial distribution of structures. In constructed catchments, structural features are determined primarily by the construction processes and the geological origin of the parent material. Objectives are scenarios of 3D catchment structures in form of complete 3D description of soil hydraulic properties generated from the knowledge of the formation processes. The constructed hydrological catchment 'Hühnerwasser' (Lower Lusatia, Brandenburg, Germany) was used for the calibration and validation of model results due to its well-known conditions. For the modeling of structural features, a structure generator was used to model i) quasi-deterministic sediment distributions using input data from a geological model of the parent material excavation site; ii) sediment distributions that are conditioned to measurement data from soil sampling; and iii) stochastic component sediment distributions. All three approaches allow a randomization within definable limits. Furthermore, the spoil cone / spoil ridge orientation, internal layering, surface compaction and internal spoil cone compaction were modified. These generated structural models were incorporated in a gridded 3D volume model constructed with the GOCAD software. The impact of structure variation was assessed by hydrological modeling with HYDRUS 2D/3D software. 3D distributions of soil hydraulic properties were estimated based on generated sediment properties using adapted pedotransfer functions. Results were compared with hydrological monitoring data. The impact of structural feature variation on hydrological behavior was analyzed by comparing different simulation scenarios. The established initial sediment distributions provide a basis for the

  19. Structure and conformation of peptides at air/aqueous interface and their impact on interfacial water structure

    Science.gov (United States)

    Chandra Jena, Kailash; Tomar, Deepak

    Process of protein folding is very essential for the proper functioning of the protein molecules at membrane surface and other organelles. Understanding the process of protein folding at various biological relevant aqueous interfaces are very important to understand various complicated chemical and physical processes relevant to chemistry, physics, and medicine. The building blocks of proteins molecules are amino acids and the chemistry of each amino acid is very different; as a consequence their sequence plays an important role for various conformations upon adsorption for the protein molecules. In the present study, we have investigated the interfacial structure and conformation of two amino acids (L-Proline and L-Tyrosine) and peptide molecules formed from these two amino acids (L-Tyr-Pro). We have used sum frequency generation (SFG) vibrational spectroscopy to probe the air/aqueous interface. We have studied the impact of adsorption of the amino acids and the peptide molecules on the interfacial water structure by slowly varying concentration and ionic strength of the solutions. Our preliminary result shows a huge impact of the adsorption process of peptide molecules on the hydrogen bonding environment of interfacial structure of water. Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab-140001.

  20. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    Science.gov (United States)

    Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

    2010-01-01

    Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

  1. THE IMPACT OF CORPORATE GOVERNANCE DIMENSIONS ON FINANCIAL STRUCTURE OF THE COMPANIES IN DEVELOPING COUNTRIES

    Directory of Open Access Journals (Sweden)

    IONESCU ALIN

    2014-12-01

    Full Text Available Corporate governance represents a current topic for academic community and practitioners, in the context of globalization and crisis, especially in case of developing countries. The main purpose of this paper is to analyze which dimensions of corporate governance are able to exercise a significant impact on the companies’ financial structure, using a dataset with 77 developing countries from Africa, Asia, Latin America and Central and Eastern Europe. The data are provided from World Bank Enterprise Survey website and the variables are grouped in two directions: corporate governance and financial structure variables. In this regard, using principal components analysis approach, we grouped firstly the variables related to financial structure and then variables related to the main four dimensions of corporate governance, such as ownership structure and management quality, transparency, environment and corruption. The impact of corporate governance dimensions on companies’ financial structure was analyzed in a generalized linear model framework and the main result of this paper consists in the fact that, for analyzed countries, companies’ financial structure is significantly influenced by several dimensions of the governance like transparency, environment or corruption

  2. THE IMPACT OF CORPORATE GOVERNANCE DIMENSIONS ON FINANCIAL STRUCTURE OF THE COMPANIES IN DEVELOPING COUNTRIES

    Directory of Open Access Journals (Sweden)

    IONESCU ALIN

    2014-12-01

    Full Text Available Corporate governance represents a current topic for academic community and practitioners, in the context of globalization and crisis, especially in case of developing countries. The main purpose of this paper is to analyze which dimensions of corporate governance are able to exercise a significant impact on the companies’ financial structure, using a dataset with 77 developing countries from Africa, Asia, Latin America and Central and Eastern Europe. The data are provided from World Bank Enterprise Survey website and the variables are grouped in two directions: corporate governance and financial structure variables. In this regard, using principal components analysis approach, we grouped firstly the variables related to financial structure and then variables related to the main four dimensions of corporate governance, such as ownership structure and management quality, transparency, environment and corruption. The impact of corporate governance dimensions on companies’ financial structure was analyzed in a generalized linear model framework and the main result of this paper consists in the fact that, for analyzed countries, companies’ financial structure is significantly influenced by several dimensions of the governance like transparency, environment or corruption.

  3. Impact

    NARCIS (Netherlands)

    Lohse, Detlef; Bergmann, Raymond; Mikkelsen, Rene; Zeilstra, Christiaan; Meer, van der Devaraj; Versluis, Michel

    2004-01-01

    A lot of information on impacts of solid bodies on planets has been extracted from remote observations of impact craters on planetary surfaces; experiments however with large enough impact energies as compared to the energy stored in the ground are difficult. We approach this problem by downscaled e

  4. Island Bay Wilderness study area : Island Bay National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a brief report on a wilderness study area located in the Island Bay National Wildlife Refuge. It discusses the history of the study area, its...

  5. Anthropogenic impacts on tropical forest biodiversity: a network structure and ecosystem functioning perspective.

    Science.gov (United States)

    Morris, Rebecca J

    2010-11-27

    Huge areas of diverse tropical forest are lost or degraded every year with dramatic consequences for biodiversity. Deforestation and fragmentation, over-exploitation, invasive species and climate change are the main drivers of tropical forest biodiversity loss. Most studies investigating these threats have focused on changes in species richness or species diversity. However, if we are to understand the absolute and long-term effects of anthropogenic impacts on tropical forests, we should also consider the interactions between species, how those species are organized in networks, and the function that those species perform. I discuss our current knowledge of network structure and ecosystem functioning, highlighting empirical examples of their response to anthropogenic impacts. I consider the future prospects for tropical forest biodiversity, focusing on biodiversity and ecosystem functioning in secondary forest. Finally, I propose directions for future research to help us better understand the effects of anthropogenic impacts on tropical forest biodiversity.

  6. The impact of information technology on productivity using structural equations technique in Iran Behnoush Company

    Directory of Open Access Journals (Sweden)

    Mina Beig

    2012-08-01

    Full Text Available Information technology plays an important role on increasing productivity in many organizations. The primary objective of the present survey is to study the impact of information technology on productivity and find a positive and significant relationship between these two factors. Structural equations technique and LISREL software are used for analysis of the questionnaires distributed among managers and some employees of Iran Behnoush Company. Organizations try to improve their performance by investment in information technology. However, many of the previous studies indicate insignificance of the impact of information technology on productivity of the organizations. The present survey studies the impact of information technology on organizations' productivity through the collected data from the above company. Results confirm existence of a positive relationship between information technology and productivity.

  7. Impact and structure of literature on nanoparticle generation by laser ablation in liquids

    Science.gov (United States)

    Barcikowski, Stephan; Devesa, Francisco; Moldenhauer, Kirsten

    2009-11-01

    The number of publications on laser ablation and nanoparticle generation in liquids increased by the factor of 15 in the last decade, with comparable high impact of the most cited articles in this field. A nearly unlimited variety of nanoparticle material, liquid matrix, and conjugative agent can be combined to a huge variety of colloids within a few minutes of laser processing. However, this diversification makes it hard to identify main research directions without a comprehensive literature overview. This investigation evaluates the impact and structure of the literature in this field tagging most prolific subjects and articles. Using an optimized search algorithm, the data sets derived from Science Citation Index (1998-2008) allow for statements on publication subject clusters, impact of articles and journals, as well as mapping global spots of activities.

  8. IRIS-2012 OECD/NEA/CSNI benchmark: Numerical simulations of structural impact

    Energy Technology Data Exchange (ETDEWEB)

    Orbovic, Nebojsa, E-mail: nebojsa.orbovic@cnsc-ccsn.gc.ca [Canadian Nuclear Safety Commission, Ottawa, ON (Canada); Tarallo, Francois [IRSN, Fontenay aux Roses (France); Rambach, Jean-Mathieu [Géodynamique et Structures, Bagneux (France); Sagals, Genadijs; Blahoianu, Andrei [Canadian Nuclear Safety Commission, Ottawa, ON (Canada)

    2015-12-15

    A benchmark of numerical simulations related to the missile impact on reinforced concrete (RC) slabs has been launched in the frame of OECD/NEA/CSNI research program “Improving Robustness Assessment Methodologies for Structures Impacted by Missiles”, under the acronym IRIS. The goal of the research program is to simulate RC structural, flexural and punching, behavior under deformable and rigid missile impact. The first phase called IRIS-2010 was a blind prediction of the tests performed at VTT facility in Espoo, Finland. The two simulations were performed related to two series of tests: (1) two tests on the impact of a deformable missile exhibiting damage mainly by flexural (so-called “flexural tests”) or global response and (2) three tests on the impact of a rigid missile exhibiting damage mainly by punching response (so-called “punching tests”) or local response. The simulation results showed significant scatter (coefficient of variation up to 132%) for both flexural and punching cases. The IRIS-2012 is the second, post-test, phase of the benchmark with the goal to improve simulations and reduce the scatter of the results. Based on the IRIS-2010 recommendations and to better calibrate concrete constitutive models, a series of tri-axial tests as well as Brazilian tests were performed as a part of the IRIS-2012 benchmark. 25 teams from 11 countries took part in this exercise. Majority of participants were part of the IRIS-2010 benchmark. Participants showed significant improvement in reducing epistemic uncertainties in impact simulations. Several teams presented both finite element (FE) and simplified analysis as per recommendations of the IRIS-2010. The improvements were at the level of simulation results but also at the level of understanding of impact phenomena and its modeling. Due to the complexity of the physical phenomena and its simulation (high geometric and material non-linear behavior) and inherent epistemic and aleatory uncertainties, the

  9. Evidence for a spatially extensive hydrothermal system at the Ries impact structure, Germany

    Science.gov (United States)

    Sapers, H. M.; Osinski, G. R.; Flemming, R. L.; Buitenhuis, E.; Banerjee, N. R.; Tornabene, L. L.; Blain, S.; Hainge, J.

    2017-02-01

    The 15 Ma, 26 km diameter Ries impact structure in south-central Germany was one of the first terrestrial impact structures where evidence of impact-associated hydrothermal alteration was recognized. Previous studies suggested that pervasive, high-temperature hydrothermal activity was restricted to the area within the "inner ring" (i.e., the crater-fill impactite units). Here we present mineralogical evidence for localized hydrothermal activity in the ejecta beyond the crater rim in two previously unstudied settings: a pervasively altered lens of suevite ejecta directly overlying the Bunte Breccia at the Aumühle quarry; and suevite ejecta at depth overlain by 20 m of lacustrine sediments sampled by the Wörnitzostheim 1965 drill core. A comprehensive set of X-ray diffraction analyses indicates five distinct alteration regimes (1) surficial ambient weathering characterized by smectite and a minor illitic component; (2) locally restricted hydrothermal activity characterized by an illitic component and minor smectite; (3) hydrothermal activity at depth characterized by smectite, a minor illitic component, and calcite; (4) hydrothermal activity at depth characterized by smectite, a minor illitic component, calcite, zeolites, and clinochlore; and (5) pervasive hydrothermal activity at depth characterized by smectite, a minor illitic component, and minor clinochlore. These data spatially extend the Ries postimpact hydrothermal system suggesting a much more extensive, complex, and dynamic system than previously thought. Constraining the mineralogical alteration regimes at the Ries impact structure may also further our understanding of impact-associated phyllosilicate formation on Mars with implications for climate models and habitability.

  10. New links between the Chicxulub impact structure and the Cretaceous/Tertiary boundary

    Science.gov (United States)

    Sharpton, V.L.; Dalrymple, G.B.; Marin, L.E.; Ryder, G.; Schuraytz, B.C.; Urrutia-Fucugauchi, J.

    1992-01-01

    THE 200-km-diameter Chicxulub structure1-3 in northern Yucatan, Mexico has emerged as the prime candidate for the Cretaceous/Tertiary (K/T) boundary impact crater3-6. Concentric geophysical anomalies associated with enigmatic occurrences of Upper Cretaceous breccias and andesitic rocks led Penfield and Camargo1 to suspect that this structure was a buried impact basin. More recently, the discovery of shocked quartz grains in a Chicxulub breccia3, and chemical similarities between Chicxulub rocks and K/T tektite-like glasses3-6 have been advanced as evidence that the Chicxulub structure is a K/T impact site. Here we present evidence from core samples that Chicxulub is indeed a K/T source crater, and can apparently account for all the evidence of impact distributed globally at the K/T boundary without the need for simultaneous multiple impacts or comet showers. Shocked breccia clasts found in the cores are similar to shocked lithic fragments found worldwide in the K/T boundary ejecta layer7,8. The Chicxulub melt rocks that we studied contain anomalously high levels of iridium (up to 13.5 parts per 109), also consistent with the indium-enriched K/T boundary layer9. Our best estimate of the crystallization age of these melt rocks, as determined by 40Ar/39Ar analyses, is 65.2??0.4 (1??) Myr, in good agreement with the mean plateau age of 64.98 ?? 0.05 Myr recently reported10. Furthermore, these melt rocks acquired a remanent magnetization indicating that they cooled during an episode of reversed geomagnetic polarity. The only such episode consistent with 40Ar/39Ar constraints is chron 29R, which includes the K/T boundary.

  11. Market impact and structure dynamics of the Chinese stock market based on partial correlation analysis

    Science.gov (United States)

    Li, Xing; Qiu, Tian; Chen, Guang; Zhong, Li-Xin; Wu, Xiao-Run

    2017-04-01

    Partial correlation analysis is employed to study the market impact on the Chinese stock market from both the native and external markets. Whereas the native market index is observed to have a great impact on the market correlations for both the Shanghai and Shenzhen stock markets, some external stock indices of the United States, European and Asian stock markets show a slight influence on the Chinese market. The individual stock can be affected by different economic sectors, but the dominant influence is from the sector the stock itself belongs to or closely related to, and the finance and insurance sector shows a weaker correlation with other economic sectors. Moreover, the market structure similarity exhibits a negative correlation with the price return in most time, and the structure similarity decays with the time interval.

  12. Impact of Firm Specific Factors on Capital Structure Decision: An Empirical Study of Bangladeshi Companies

    Directory of Open Access Journals (Sweden)

    Md. Faruk Hossain

    2012-08-01

    Full Text Available Abstract This study attempts to explore the impact of firm specific factors on capital structure decision for a sample of 39-firm listed on Dhaka Stock Exchange (DSE during 2003-2007. To achieve the objectives, this study tests a null hypothesis that none of the firm’s specific factors namely profitability, tangibility, non-debt tax shield, growth opportunities, liquidity, earnings volatility, size, dividend payment, managerial ownership, and industry classification has significant impact on leverage using estimate of fixed effect model under Ordinary Least Square (OLS regression. Checking multicollinearity and estimating regression analysis through Pearson correlation and autoregressive mode respectively this study found that profitability, tangibility, liquidity, and managerial ownership have significant and negative impact on leverage. Positive and significant impact of growth opportunity and non-debt tax shield on leverage has been found in this study. On the other hand size, earnings volatility, and dividend payment were not found to be significant explanatory variables of leverage. Results also reveal that total debt to total assets ratios are significantly different across Bangladeshi industries. Keywords: Capital structure, Leverage, Firm’s specific factors, Dhaka Stock Exchange Bangladesh.

  13. IMPACT OF THE GLOBAL CRISIS ON THE GOVERNANCE STRUCTURES OF INTERNATIONAL FINANCIAL INSTITUTIONS

    Directory of Open Access Journals (Sweden)

    Gökhan Özkan

    2011-11-01

    Full Text Available The global financial crisis dragged many countries into recession, demonstrated that the internationalfinancial system has structural problems and started discussions about restructuring of the international financialinstitutions. The main objective of this paper is to investigate the impact of the global financial crisis on thegovernance structures of the international financial institutions. To this end, studies made at different internationalplatforms were evaluated. The debates and negotiations among the developed and developing countries aboutgovernance structures of the international financial institutions were analyzed. Developing countries’ demand toreform the decision-making mechanisms of the Bretton Woods institutions, the IMF and the World Bank anddeveloped countries’ reservations were investigated. It was concluded that the new shape of the internationalfinancial architecture and governance structures of international financial institutions will depend on internationalpolitics as well as the evolution of the global crisis and the economic dynamics.

  14. The impact of family structure on the health of children: Effects of divorce.

    Science.gov (United States)

    Anderson, Jane

    2014-11-01

    Nearly three decades of research evaluating the impact of family structure on the health and well-being of children demonstrates that children living with their married, biological parents consistently have better physical, emotional, and academic well-being. Pediatricians and society should promote the family structure that has the best chance of producing healthy children. The best scientific literature to date suggests that, with the exception of parents faced with unresolvable marital violence, children fare better when parents work at maintaining the marriage. Consequently, society should make every effort to support healthy marriages and to discourage married couples from divorcing.

  15. Influence of Thermal Homogenization Treatment on Structure and Impact Toughness of H13 ESR Steel

    Institute of Scientific and Technical Information of China (English)

    MA Dang-shen; ZHOU Jian; CHEN Zai-zhi; ZHANG Zhong-kan; CHEN Qi-an; LI De-hui

    2009-01-01

    The as-cast microstrueture of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that the dendrite arm spacing gradually becomes wide from the surface to the center of ingot, and the large primary carbide particles always exist in interdendritic segregation areas; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropic properties have been improved remarkably.

  16. Tax structure in Latin American : its impact on the real economy

    OpenAIRE

    Martínez Vázquez, Jorge; Vulovic, Violeta

    2014-01-01

    In this paper we review the structure of tax systems in Latin America and analyze their impact on the real economy - economic growth, macro-economic stability, and income redistribution. We find that in Latin America relatively higher reliance on direct taxes slows economic growth, although this effect is smaller than in the ‘Rest of the World.’ However, unlike in most other countries, higher reliance on direct taxes in Latin America does not appear to play a significant rol...

  17. Evaluation of computer programs used for structural analyses of impact response of spent fuel shipping casks

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, B A; Gwinn, K W

    1984-05-01

    This report presents the results of a study of impact analyses of a generic spent-fuel cask. The study compares the use and results of three different finite element computer codes. Seven different cask-like model analyses are considered. The models encompass both linear and nonlinear geometric and material behavior. On the basis of the analyses results, this report recommends what parameters are useful in the comparison of different structural finite element computer programs. 5 references, 36 figures, 11 tables.

  18. Impact of new computing systems on computational mechanics and flight-vehicle structures technology

    Science.gov (United States)

    Noor, A. K.; Storaasli, O. O.; Fulton, R. E.

    1984-01-01

    Advances in computer technology which may have an impact on computational mechanics and flight vehicle structures technology were reviewed. The characteristics of supersystems, highly parallel systems, and small systems are summarized. The interrelations of numerical algorithms and software with parallel architectures are discussed. A scenario for future hardware/software environment and engineering analysis systems is presented. Research areas with potential for improving the effectiveness of analysis methods in the new environment are identified.

  19. Double-hump resonance structure of the cross sections for electron impact ionization of Ar5+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Configuration-average distorted-wave calculations are carried out for electron-impact ionization of Ar5+. Both direct ionization and the indirect excitation autoionization processes are included in our calculations. Our theoretical values are in quite reasonable agreement with the experimental data. The indirect processes contribute up to 50% to the total ionization cross sections. The possible origin of double-hump resonance structure of the cross sections is demonstrated and the contributions of metastable states are also taken into account.

  20. Impact of distribution intensity on perceived quality, brand awareness and brand loyality - structural model

    OpenAIRE

    Ivan-Damir Anić; Edo Rajh

    2008-01-01

    The purpose of this empirical study was to determine the impacts of distribution intensity on perceived quality and brand awareness, and to analyze the effects of perceived quality and brand awareness on brand loyalty. A structural equation model was used to identify the size and the direction of proposed relationships. The model was tested on a sample of 956 students using three brand categories in the manufacturing industry and three brand categories in the service industry. The proposed hy...

  1. Small x nonlinear evolution with impact parameter and the structure function data

    CERN Document Server

    Berger, Jeffrey

    2011-01-01

    Nonlinear evolution at small values of Bjorken x is evaluated numerically using the dipole framework with impact parameter dependence. Confinement effects are modeled by including masses into the evolution. Sensitivity of the predictions due to different prescriptions of the cuts on large dipole sizes is investigated. Running coupling effects are taken into account in this analysis. Finally, a comparison with the inclusive data from HERA on the structure functions F2 and FL is performed.

  2. Design aspects of high strength steel welded structures improved by high frequency mechanical impact (HFMI) treatment

    OpenAIRE

    Yildirim, Halid Can

    2013-01-01

    This doctoral study is concerned with the fatigue strength of welded steel structures which are improved by high frequency mechanical impact (HFMI) treatment. A comprehensive evaluation of 417 HFMI test data obtained from the literature and 24 HFMI fatigue data tested as a part of this work are studied. According to the statistical analyses an S-N slope of five (5) is proposed. A yield strength correction procedure which relates the material yield strength (fy) to fatigue is presented and ver...

  3. Application of organic geochemistry to detect signatures of organic matter in the Haughton impact structure

    Science.gov (United States)

    Parnell, John; Lee, Pascal; Osinski, Gordon R.; Cockell, Charles S.

    2005-12-01

    Organic geochemistry applied to samples of bedrock and surface sediment from the Haughton impact structure detects a range of signatures representing the impact event and the transfer of organic matter from the crater bedrock to its erosion products. The bedrock dolomite contains hydrocarbon-bearing fluid inclusions which were incorporated before the impact event. Comparison of biomarker data from the hydrocarbons in samples inside and outside of the crater show the thermal signature of an impact. The occurrence of hydrocarbon inclusions in hydrothermal mineral samples shows that organic matter was mobilized and migrated in the immediate aftermath of the impact. The hydrocarbon signature was then transferred from bedrock to the crater-fill lacustrine deposits and present-day sediments in the crater, including wind-blown detritus in snow/ice. Separate signatures are detected from modern microbial life in crater rock and sediment samples. Signatures in Haughton crater samples are readily detectable because they include hydrocarbons generated by the burial of organic matter. This type of organic matter is not expected in crater samples on other planets, but the Haughton data show that, using very high resolution detection of organic compounds, any signature of primitive life in the crater rocks could be transferred to surface detritus and so extend the sampling medium.

  4. Evidence for a Meteoritic Component in Impact Melt Rock from the Chicxulub Structure

    Science.gov (United States)

    Koeberl, Christian; Sharpton, Virgil L.; Schuraytz, Benjamin C.; Shirey, Steven B.; Blum, Joel D.; Marin, Luis E.

    1994-01-01

    The Chicxulub structure in Yucatan, Mexico, has recently been recognized as a greater then 200-km-diameter multi-ring impact crater of K-T boundary age. Crystalline impact melt rocks and breccias from within the crater, which have compositions similar to those of normal continental crustal rocks and which show shock metamorphic effects, have been studied for trace element and Re-Os isotope compositions. Re-Os isotope systematics allow the sensitive and selective determination of an extraterrestrial component in impact-derived rocks. A melt rock sample shows elevated iridium concentrations, an osmium concentration of 25 ppb, and a low Os-187/Os-188 ratio of 0.113, which are incompatible with derivation from the continental crust. Even though the Os-187/Os-188 ratio is slightly lower than the range so far measured in meteorites, a mantle origin seems unlikely for mass balance reasons and because the cratering event is unlikely to have excavated mantle material. The data support the hypothesis of a heterogeneously distributed meteoritic component in the Chicxulub melt rock. A sample of impact glass from the Haitian K-T boundary at Beloc yielded about 0.1 ppb osmium and an Os-187/0s-188 ratio of 0.251, indicating the presence of a small meteoritic component in the impact ejecta as well.

  5. Geochemical evidence from the Sudbury structure for crustal redistribution by large bolide impacts.

    Science.gov (United States)

    Mungall, James E; Ames, Doreen E; Hanley, Jacob J

    2004-06-03

    Deformation and melting of the crust during the formation of large impact craters must have been important during the Earth's early evolution, but such processes remain poorly understood. The 1.8-billion-year-old Sudbury structure in Ontario, Canada, is greater than 200 km in diameter and preserves a complete impact section, including shocked basement rocks, an impact melt sheet and fallback material. It has generally been thought that the most voluminous impact melts represent the average composition of the continental crust, but here we show that the melt sheet now preserved as the Sudbury Igneous Complex is derived predominantly from the lower crust. We therefore infer that the hypervelocity impact caused a partial inversion of the compositional layering of the continental crust. Using geochemical data, including platinum-group-element abundances, we also show that the matrix of the overlying clast-laden Onaping Formation represents a mixture of the original surficial sedimentary strata, shock-melted lower crust and the impactor itself.

  6. Tidal Mixing Box Submodel for Tampa Bay: Calibration of Tidal Exchange Flows with the Parameter Estimation Tool (PEST)

    Science.gov (United States)

    In the mid-1990s the Tampa Bay Estuary Program proposed a nutrient reduction strategy focused on improving water clarity to promote seagrass expansion within Tampa Bay. A System Dynamics Model is being developed to evaluate spatially and temporally explicit impacts of nutrient r...

  7. Assessing the cumulative impact of disturbance on canopy structure and chemistry in Appalachian forests

    Science.gov (United States)

    Deel, Lindsay N.

    Eastern forests experience a range of disturbance events over time, from stand-replacing disturbances, such as clear cuts, to ephemeral disturbances, such as insect outbreaks. By understanding the cumulative impact of disturbances on canopy structure and chemistry, we can gain insight into management strategies, assess a variety of ecosystem services, and even contribute to a larger body of knowledge on global climate change. I transformed a series of Landsat images spanning approximately 25 years into cumulative disturbance maps covering Green Ridge State Forest and Savage River State Forest in western Maryland. Intensive field surveys collected during the summer of 2009 provided measurements of canopy N and estimates of canopy cover, understory cover, and leaf cover. I used AVIRIS imagery flown concurrently with field data collection to map canopy nitrogen across both forests. Through this project, I tested the impact of cumulative disturbance on forest canopy cover and canopy nitrogen. I found that increased values of cumulative disturbance had a measurable negative impact on forest canopy structure and canopy nitrogen. Moreover, by testing varying methods of summing cumulative disturbance, I found that past disturbances diminish over time in importance, yet still influence the current canopy structure and canopy N of a forest. Thus, my study suggests that Landsat time series data can be synthesized into cumulative metrics incorporating multiple disturbance types, which help explain important disturbance-mediated changes in ecosystem functions.

  8. Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding

    Science.gov (United States)

    Ryan, Shannon; Christiansen, Eric L.

    2013-02-01

    A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

  9. Molecular dynamics study of crater formation by core-shell structured cluster impact

    Science.gov (United States)

    Aoki, Takaaki; Seki, Toshio; Matsuo, Jiro

    2012-07-01

    Crater formation processes by the impacts of large clusters with binary atomic species were studied using molecular dynamics (MD) simulations. Argon and xenon atoms are artificially organized in core-shell cluster structures with various component ratios and irradiated on a Si(1 0 0) target surface. When the cluster has Xe1000 core covered with 1000 Ar atoms, and impacts at a total of 20 keV, the core Xe cluster penetrates into the deep area, and a crater with a conical shape is left on the target. On the other hand, in the case of a cluster with the opposite structure, Ar1000 core covered with 1000 Xe atoms, the cluster stops at a shallow area of the target. The incident cluster atoms are mixed and tend to spread in a lateral direction, which results in a square shaped crater with a shallower hole and wider opening. The MD simulations suggest that large cluster impacts cause different irradiation effects by changing the structure, even if the component ratio is the same.

  10. Lavaca Bay 1985-1987

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Samples were collected from October 15, 1985 through June 12, 1987 in emergent marsh and non-vegetated habitats throughout the Lavaca Bay system to characterize...

  11. Back Bay Wilderness area description

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a description of the lands located within the Back Bay National Wildlife Refuge. Within these lands, it designates which area is suitable for...

  12. Annual report, Bristol Bay, 1955

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Commercial fishery management activities for Bristol Bay for 1955, including lists of operators, extensive statistics, descriptions of enforcement activities, and...

  13. FL BAY SPECTROUT-DIET

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Juvenile spotted seatrout and other sportfish are being monitored annually over a 6-mo period in Florida Bay to assess their abundance over time relative to...

  14. Annual report, Bristol Bay, 1958

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Commercial fishery management activities for Bristol Bay for 1958, including lists of operators, extensive statistics, and descriptions of enforcement activities.

  15. Vapor Intrusion Facilities - South Bay

    Data.gov (United States)

    U.S. Environmental Protection Agency — POINT locations for the South Bay Vapor Instrusion Sites were derived from the NPL data for Region 9. One site, Philips Semiconductor, was extracted from the...

  16. Maps showing textural characteristics of benthic sediments in the Corpus Christi Bay estuarine system, south Texas

    Science.gov (United States)

    Shideler, Gerald L.; Stelting, Charles E.; McGowen, Joseph H.

    1981-01-01

    Corpus Christi Bay is a heavily used estuary on the south Texas coast in the northwest Gulf of Mexico (fig. 1).  The Bay is stressed by diverse activities which could substantially affect its ecosystem.  Such activities include shipping, resource production (oil, gas, and construction aggregate), commercial and sport fishing, and recreation.  Shipping activities alone have had a substantial impact on the bay.  For example, the past maintenance of navigation channels has required extensive dredging and spoil disposal within the estuarine system.  Numerous subaqueous spoil disposal sites and subaerial spoil banks are present throughout the bay (fig. 1), and the selection of future spoil disposal sites is becoming a critical local problem.  As activities in the bay increase, the need for effective environmental management becomes increasingly important, and effective management necessitates a good understanding of the bay's physical characteristics.  The objective of this study is to provide detailed information about the textural composition of bottom sediments within the estuarine system, information which could be used in making environmental-management decisions.  Visual descriptions of bottom sediments in Corpus Christi Bay and adjacent areas have been presented by McGowen and Morton (1979).  Additionally, a study of the textures of sediments on the Inner Continental Shelf adjacent to the bay has been presented by Shideler and Berryhill (1977).

  17. Typical structural elements of seismicity and impact crater morphology identified in GIS ENDDB digital models.

    Science.gov (United States)

    Mikheeva, Anna

    2014-05-01

    The subject database of the ENDDB system (Earth's Natural Disasters Database) is a combination of the EISC catalog (Earth's impact structures Catalog [1]) and seismological data of more than 60 earthquake catalogs (EC). ENDDB geographic subsystem uses the NASA ASTER GDEM data arrays to obtain a high-resolution (1 arc-second) shaded relief model, as well as the digital mapping technology, which consists in shading surface points according to their brightness controlled by the illumination angle. For example, the identifying impact craters by means of ENDDB begins with selecting the optimum base colors of the image, the parameters of illumination and shadow depth for constructing a shaded model on a regular grid of values. This procedure allows obtaining precise 3D images of the terrain and gravity patterns, and, moreover, furnishes data for recognizing standard morphological elements according to which impact structures can be visually detected. For constructing a shaded gravity anomaly wit