WorldWideScience

Sample records for prograding delta system

  1. Balancing Aggradation and Progradation on a Vegetated Delta: The Importance of Fluctuating Discharge in Depositional Systems

    Science.gov (United States)

    Piliouras, Anastasia; Kim, Wonsuck; Carlson, Brandee

    2017-10-01

    Vegetation is an important component of constructional landscapes, as plants enhance deposition and provide organic sediment that can increase aggradation rates to combat land loss. We conducted two sets of laboratory experiments using alfalfa (Medicago sativa) to determine the effects of plants on channel organization and large-scale delta dynamics. In the first set, we found that rapid vegetation colonization enhanced deposition but inhibited channelization via increased form drag that reduced the shear stress available for sediment entrainment and transport. A second set of experiments used discharge fluctuations between flood and base flow (or interflood). Interfloods were critical for reworking the topset via channel incision and lateral migration to create channel relief and prevent rapid plant colonization. These low-flow periods also greatly reduced the topset slope in the absence of vegetation by removing topset sediment and delivering it to the shoreline. Floods decreased relief by filling channels with sediment, resulting in periods of rapid progradation and enhanced aggradation over the topset surface, which was amplified by vegetation. The combination of discharge fluctuations and vegetation thus provided a balance of vertical aggradation and lateral progradation. We conclude that plants can inhibit channelization in depositional systems and that discharge fluctuations encourage channel network organization to naturally balance against aggradation. Thus, variations in discharge are an important aspect of understanding the ecomorphodynamics of aggrading surfaces and modeling vegetated deltaic systems, and the combined influences of plants and discharge variations can act to balance vertical and lateral delta growth.

  2. Delta progradation in Greenland driven by increasing glacial mass loss

    DEFF Research Database (Denmark)

    Bendixen, Mette; Iversen, Lars Lonsmann; Bjork, Anders Anker

    2017-01-01

    Climate changes are pronounced in Arctic regions and increase the vulnerability of the Arctic coastal zone(1). For example, increases in melting of the Greenland Ice Sheet and reductions in sea ice and permafrost distribution are likely to alter coastal morphodynamics. The deltas of Greenland...... imagery. We find that delta progradation was driven by high freshwater runoff from the Greenland Ice Sheet coinciding with periods of open water. Progradation was controlled by the local initial environmental conditions (that is, accumulated air temperatures above 0 degrees C per year, freshwater runoff...... are largely unaffected by human activity, but increased freshwater runoff and sediment fluxes may increase the size of the deltas, whereas increased wave activity in ice-free periods could reduce their size, with the net impact being unclear until now. Here we show that southwestern Greenland deltas were...

  3. Delta progradation in Greenland driven by increasing glacial mass loss

    Science.gov (United States)

    Bendixen, Mette; Lønsmann Iversen, Lars; Anker Bjørk, Anders; Elberling, Bo; Westergaard-Nielsen, Andreas; Overeem, Irina; Barnhart, Katy R.; Abbas Khan, Shfaqat; Box, Jason E.; Abermann, Jakob; Langley, Kirsty; Kroon, Aart

    2017-10-01

    Climate changes are pronounced in Arctic regions and increase the vulnerability of the Arctic coastal zone. For example, increases in melting of the Greenland Ice Sheet and reductions in sea ice and permafrost distribution are likely to alter coastal morphodynamics. The deltas of Greenland are largely unaffected by human activity, but increased freshwater runoff and sediment fluxes may increase the size of the deltas, whereas increased wave activity in ice-free periods could reduce their size, with the net impact being unclear until now. Here we show that southwestern Greenland deltas were largely stable from the 1940s to 1980s, but prograded (that is, sediment deposition extended the delta into the sea) in a warming Arctic from the 1980s to 2010s. Our results are based on the areal changes of 121 deltas since the 1940s, assessed using newly discovered aerial photographs and remotely sensed imagery. We find that delta progradation was driven by high freshwater runoff from the Greenland Ice Sheet coinciding with periods of open water. Progradation was controlled by the local initial environmental conditions (that is, accumulated air temperatures above 0 °C per year, freshwater runoff and sea ice in the 1980s) rather than by local changes in these conditions from the 1980s to 2010s at each delta. This is in contrast to a dominantly eroding trend of Arctic sedimentary coasts along the coastal plains of Alaska, Siberia and western Canada, and to the spatially variable patterns of erosion and accretion along the large deltas of the main rivers in the Arctic. Our results improve the understanding of Arctic coastal evolution in a changing climate, and reveal the impacts on coastal areas of increasing ice mass loss and the associated freshwater runoff and lengthening of open-water periods.

  4. Morphodynamics of a cyclic prograding delta: the Red River, Vietnam

    NARCIS (Netherlands)

    Maren, D.S. van

    2004-01-01

    River deltas are inhabited by over 60% of the world population, and are, consequently, of paramount agricultural and economical importance. They constitute unique wetland envi ronments which gives river deltas ecological importance as well. Additionally, many deltas contain large accumulations of

  5. The Oligo-Miocene of Eil (NE Somalia): a prograding coral- Lepidocyclina system

    Science.gov (United States)

    Bosellini, A.; Russo, A.; Arush, M. A.; Cabdulqadir, M. M.

    The Oligo-Miocene succession of Eil is the product of a depositional regression and constitutes a 120-150 m thick depositional sequence that prograded seaward for at least 20-25 km. Its time-transgressive stratigraphy is documented physically by well exposed tangential clinoforms (previously considered as evidence of a tectonic coastal flexure) and biostratigraphically by the occurrence of calcareous nannoplankton, planktonic and benthonic foraminifera, and a rich coral fauna. The upper boundary of the sequence is indicated by a reefal toplap, which constitutes the flat surface of the Nogal Plateau. Age (Chattian to Burdigalian) and toplap relationships of the sequence indicate clearly that progradation took place after the Late Oligocene flooding which followed the strong fall of sea-level during the Chattian. Because of the horizontal geometry of the entire sedimentary system, it has been possible to make a clear environmental reconstruction and a facies model with original water depths. A worldwide Tertiary facies—the Lepidocyclina beds— was confined to the front of the reef, at depths ranging from 35-40 to 120-130 m.

  6. Depositional patterns in the modern Po delta system

    Science.gov (United States)

    Correggiari, A.; Cattaneo, A.; Trincardi, F.

    2003-04-01

    The late-Holocene Adriatic Highstand Systems Tract (HST) includes three genetically-related depocenters: 1) the Po delta and prodelta, 2) the central Adriatic prodelta wedge, fed from the Po and coalescing Apennine rivers, and 3) the Gargano subaqueous delta nourished by shore-parallel sediment advection, 600 km south of the Po delta. Progradation of the Po delta wedge started at 5.5 kyr BP and was characterised by alternating phases of rapid advance, switch and abandonment of coastal and deltaic apparatuses, resulting in a composite deposit formed by minor units. Delta and prodelta construction occurred under the forcing of high-frequency climatic change, autocyclic switches and anthropogenic causes, acting at variable but generally short time scales. During the first part of the highstand progradational phase, avulsion was an important process in delta building, and the location of avulsion sites was influenced by natural factors. After a major natural avulsion in the 12th century, the main axis of Po river transport shifted northwards and its southern branches lost their importance. Strong anthropogenic forcing on the river regime coupled with climate switch to colder conditions caused the huge outbuilding of the modern delta since the Little Ice Age (ca. 1450 - 1850 AD), resulting in a complete re-shaping of the northern Adriatic shoreline. Two different types of depositional patterns are detectable from VHR sesmic lines recorded offshore: a) the delta lobes fed by individual distributary mouths, onlap onto each other and reflect autocyclic processes, driven by discharge and sediment load variations, and human interference; and b) erosional features locally detactable close to individual distributary channels. The channel-like forms record repeated episods of cut and fill; they occur isolated or in clusters with widths of 10-30 m and depths up to 4 m. These features could be related to episodic catastrophic reactivation of Po river branches, driven by man needs

  7. Gamma-ray dose rate surveys help investigating century-scale beach ridge progradation in the wave-dominated Catumbela delta (Angola)

    Science.gov (United States)

    Dinis, Pedro A.; Pereira, Alcides C.; Quinzeca, Domingos; Jombi, Domingos

    2017-10-01

    A strandplain at the downdrift side of the wave-dominated Catumbela delta (Angola) includes distinguishable deposits with very high natural radioactivity (up to 0.44 microSv/hour). In order to establish the geometry of these sedimentary units and understand their genetic processes, dose rate surveys were performed with the portable equipment Rados RDS-40WE. In addition, grain-size distribution, heavy-mineral composition and gamma-ray mass spectra of the high dose rate deposits were analysed. High dose rate values are found in ribbon units aligned parallel to the shoreline, which are a few tens of meters wide and up to approximately 3 km long. These units reflect the concentration of Th-bearing grains in coastal deposits enriched in heavy minerals. An integrated analysis of the high dose rate ribbons in GIS environment with aerial photography and topographic maps suggests that parts of the high dose rate units formed during the last two centuries may be related with the erosion of older shoreline deposits, due to updrift displacements of the Catumbela river outlet and recycling of shoreline accumulations with downdrift deposition. Simple gamma-ray surveys carried out with a portable detector can unravel depositional units characterised by significant enrichment in heavy-mineral grains that are likely to correspond to key events in the evolution of wave-dominated accumulations. The location of such deposits should be taken into account when planning future work using more expensive or time-consuming techniques.

  8. Sequence stratigraphy and systems tract analysis of the Neogene-Quaternary continental margin off the Zambezi delta, Mozambique

    Energy Technology Data Exchange (ETDEWEB)

    Kolla, V. (Elf Exploration, Inc., Houston, TX (United States)); Macurda, D.B. Jr. (The Energists, Houston, TX (United States)); Nelson, H.R. Jr. (Landmark Graphics Corp., Houston, TX (United States))

    1991-03-01

    During the Neogene and Quaternary, the Zambezi River built a broad delta-platform from 75 to over 100 km into the Indian Ocean. A regional seismic grid shows numerous discontinuities in the delta platform, slope, and deeper basinal areas. Based on downward shifts of reflection terminations and onlaps at or below shelf edge, more than 25 sequences have been identified. Within the gross Neogene package, the basal section is characterized by aggradation, followed by rapid and significant (oblique) progradation, which is then followed by numerous aggradational-progradation and progradation packages in the upper, younger sections. From recognition of aggradation-progradation patterns and from well information, it appears that the first, significant, and rapid progradation occurred since mid-Miocene. The earliest of the Neogene sequence appears thicker towards south and thinner towards north, opposite of the younger sequences. The number of sequences, their modes of stacking, and thickness distributions reflect relative sea-level changes and the points of sediment input as the Zambezi River shifted in position from south to north in time. The Zambezi passive continental margin, located in the Indian Ocean basin, is a stable platform as opposed to the unstable continental margins off the Mississippi, McKenzie, and Niger deltas and is far from the stable margins that were the basis of the Haq et al. cycle-chart (1987). Thus the Zambezi continental margin provides an independent test case for verification of eustatic cycles and for the evaluation of allogenic (eustatic) versus autogenic (subsidence and delta switching) effects on depositional systems and systems tracts.

  9. Analysis and Synthesis of Delta Operator Systems

    CERN Document Server

    Yang, Hongjiu; Shi, Peng; Zhao, Ling

    2012-01-01

    This book is devoted to analysis and design on delta operator systems. When sampling is fast, a dynamical system will become difficult to control, which can be seen in wide real world applications. Delta operator approach is very effective to deal with fast sampling systems. Moreover, it is easy to observe and analyze the control effect with different sampling periods in delta operator systems. The framework of this book has been carefully constructed for delta operator systems to handle sliding mode control, time delays, filter design, finite frequency and networked control. These problems indeed are especially important and significant in automation and control systems design. Through the clear framework of the book, readers can easily go through the learning process on delta operator systems via a precise and comfortable learning sequence. Following this enjoyable trail, readers will come out knowing how to use delta operator approach to deal with control problems under fast sampling case. This book should...

  10. Late-Holocene evolution of the Mahakam delta, East Kalimantan, Indonesia

    NARCIS (Netherlands)

    Storms, J.E.A.; Hoogendoorn, R.M.; Dam, R.A.C.; Hoitink, A.J.F.; Kroonenberg, S.B.

    2005-01-01

    The late-Holocene Mahakam delta, located along the tropical eastern shore of Kalimantan, Indonesia, is considered to be a textbook example of a mixed tide-fluvial dominated delta system. The delta prograded about 60 km during the past 5000 years, which led to the development of a distinct network of

  11. A Spatio-Temporal Assessment of Landcover and Coastal Changes at Wandandian Delta System, Southeastern Australia

    Directory of Open Access Journals (Sweden)

    Ali K. M. Al-Nasrawi

    2017-11-01

    Full Text Available Large numbers of people live along and depend upon the world’s coastal resources. Human modifications of the coastal zone, in combination with climate induced environmental changes, have had a major effect on the natural ecological systems. GIS analysis of remote sensed data, combined with fieldwork and laboratory tests, can be used to determine the resultant eco-geomorphic changes that need to be managed sustainably on a worldwide scale. Modelling the eco-geomorphic dynamics between 1949 and 2016 on the Wandandian Creek delta (southeastern NSW, Australia provides a case study of management options for such coastal resources. Results from the Wandandian Creek delta show that sand/silt sediment derived from the partially (22% modified terrestrial catchment has prograded into the wave-dominated St. Georges Basin where it is impacted by nearshore processes. Clear spatio-temporal growth of the areal extent and elevation of the deltaic levees and sandspits, with their associated mangroves and saltmarshes, has occurred over the past 65 years. Although the growth rate has fluctuated during the study period, due to flood events in 1974, 1990s and 2010, the overall subaerial and subaqueous delta area has had an average growth of 4168 m2 annually with the shoreline extending 1.451 m/year on average. This geomorphic growth has stabilised the estuarine deltaic habitats with high proportions of nutrients and organic matter, particularly within saltmarsh, mangrove, Casuarina/Juncus and other mixed native plant areas. This research shows the importance of analysing morphological changes observed on the delta that can be related to both anthropogenic modifications and natural processes to the catchment and thus should be used in the development of catchment and coastal management plans.

  12. Delta Dynamics

    DEFF Research Database (Denmark)

    Bendixen, Mette

    and diminishing and prolongs the open water period and thereby the period where waves can affect the coast. Only limited work has focused on coastal areas in Greenland and the current knowledge on these areas is sparse. Coastal morphology of Greenland is highly variable spanning from rocky coasts and archipelagos....... The warming air temperature affects the soil temperature and permafrost thaws and destabilizes the material in the coastal zone. In Greenland, the warming temperature lowers the surface mass balance of the Greenland Ice Sheet and more material is transported to the coastal zone. The sea ice extent is thinning...... deltas are prograding, contrary to the global trend showing eroding Arctic coasts. Moreover, it is revealed that the increasing proglacial freshwater runoff, caused by a lowering of the surface mass balance of the Greenland Ice Sheet is the main determining agent in delta progradation. The final part...

  13. Depositional architecture and evolution of inner shelf to shelf edge delta systems since the Late Oliocene and their respone to the tectonic and sea level change, Pear River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Lin, Changsong; Zhang, Zhongtao; liu, Jingyan; Jiang, Jing

    2016-04-01

    The Pear River Mouth Basin is located in the northern continent margin of the South China Sea. Since the Late Oligocene, the long-term active fluvial systems (Paleo-Zhujiang) from the western basin margin bebouched into the northern continental margin of the South China Sea and formed widespread deltaic deposits in various depositional geomorphologies and tectonic settings. Based of integral analysys of abundant seismic, well logging and drilling core data, Depositional architecture and evolution of these delta systems and their respone to the tectonic and sea level change are documented in the study. There are two basic types of the delta systems which have been recognized: inner shelf delta deposited in shallow water enviroments and the outer shelf or shelf-edge delta systems occurred in deep water settings. The paleowater depths of these delta systems are around 30 to 80m (inner shelf delta) and 400-1000m (shelf-edge delta) estimated from the thickness (decompaction) of the delta front sequences. The study shows that the inner shelf delta systems are characterized by relatively thin delta forests (20-40m), numereous stacked distributary channel fills, relative coarse river mouth bar deposits and thin distal delta front or distal bar and prodelta deposits. In contrast, the outer shelf or shelf edge delta systems are characteristic of thick (300-800m) and steep (4-60) of deltaic clinoforms, which commonly display in 3D seismic profiles as "S" shape reflection. Large scale soft-sediment deformation structures, slump or debris flow deposits consisting mainly of soft-sediment deformed beds, blocks of sandstones and siltstones or mudstones widely developed in the delta front deposits. The shelf edge delta systems are typically associated with sandy turbidite fan deposits along the prodelta slopes, which may shift basinwards as the progradation of the delta systems. The delta systems underwent several regional cycles of evolution from inner shelf deltas to shelf edge

  14. Asymmetric progradation of a coastal mangrove forest controlled by combined fluvial and marine influence, Cù Lao Dung, Vietnam

    Science.gov (United States)

    Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Vo-Luong, H. P.

    2017-09-01

    Mangrove forests are an important means of coastal protection along many shorelines in the tropics, and are often associated with large rivers there. Isolating the contribution of any one factor to the progradation or retreat of a coastal mangrove forest is often hindered by the physical separation between sites that are subject to vastly different combinations of marine and fluvial influence. The mangrove forest at the seaward end of Cù Lao Dung, an island in the Mekong Delta, includes areas with progradation rates of 10 s m y-1, and areas that have experienced little to no progradation in recent decades. The physical proximity (<12 km) of these two environments allows detailed hydrodynamic and sediment-dynamic measurements to be related directly to morphologic change and century-scale stratigraphy. Contrary to conventional understanding, the region of mangrove forest prograding most rapidly is subject to the greatest wave attack, while progradation is slowest in the most quiescent area. Limited progradation here is the product of a reduction in the supply of sediment to certain parts of the mangrove forest due to nearby estuarine dynamics operating on spring-neap timescales. Measurements of sediment flux show net transport into the rapidly prograding part of the forest, and transport out from the part of the forest with minimal progradation. Century-scale rates of sediment accumulation determined using 210Pb geochronology are consistent with in-situ dynamical measurements and geomorphic evolution of the mangrove forest. Where progradation is most rapid, sediment accumulation rates (3.0-5.1 cm y-1) exceed the rate of local sea-level rise (∼1.5 cm y-1). In contrast, sediment-accumulation rates in the area of minimal progradation (0.8-2.8 cm y-1) only somewhat exceed the rate of local sea-level rise, if at all. Physical stratification is well preserved in cores from areas of rapid progradation, consistent with energetic transport processes and an ample sediment

  15. Automated system for simultaneous analysis of delta(13)C, delta(18)O and CO(2) concentrations in small air samples.

    Science.gov (United States)

    Ribas-Carbo, Miquel; Still, Chris; Berry, Joe

    2002-01-01

    In this paper we present an automated system for simultaneous measurement of CO(2) concentration, delta(13)C and delta(18)O from small (CMDL analyzed air samples was 0.08 ppm for the CO(2) concentration, 0.01 per thousand for delta(13)C and 0.00 per thousand for delta(18)O. A specific list of the parts and operation of the system is detailed as well as some of the applications for micrometeorological and ecophysiological applications. Copyright 2002 John Wiley & Sons, Ltd.

  16. The Mechanics of River Avulsions on Deltas

    Science.gov (United States)

    Ganti, Vamsi; Chadwick, Austin; Hassenruck-Gudipati, Hima; Lamb, Michael

    2017-04-01

    River deltas are highly dynamic, often fan-shaped depositional systems that form when rivers drain into a standing body of water. They host over a half billion people worldwide and are currently under threat of drowning and destruction by relative sea-level rise, subsidence, and anthropogenic interference. Many river deltas develop planform fan shapes through avulsions, whereby major river channel shifts occur via "channel jumping" about a persistent spatial node, thus determining their fundamental length scale. Emerging theories suggest that the size of deltas is set by backwater hydrodynamics; however, these ideas are difficult to test on natural deltas, which evolve on centennial to millennial timescales. Here, using physical experiments coupled with observations of the dynamics of modern deltaic evolution, we show that deltas grow through successive deposition of lobes that maintain a constant size that scales with backwater hydrodynamics. The preferential avulsion node in our experiments is a consequence of multiple river floods and Froude-subcritical flows that produce persistent nonuniform flows and a peak in net channel deposition within the backwater zone of the coastal river. Moreover, because the backwater hydrodynamics are controlled by the downstream boundary condition of constant sea level, the backwater-mediated avulsion sites translate seaward in step with shoreline progradation. In contrast, experimental deltas without multiple floods produce flows with uniform velocities and delta lobes that lack a characteristic size. Results have broad applications to sustainable management of deltas and for decoding their stratigraphic record on Earth and Mars.

  17. Considerations in designing an evaluation system for adaptive delta management

    NARCIS (Netherlands)

    Hermans, L.M.; Maat, J.; Haasnoot, M.; Kwakkel, J.H.

    2014-01-01

    New planning approaches put new requirements on evaluation. A recent innovation in the water domain is adaptive delta management (ADM). ADM supports long-term planning in the face of uncertainty. This paper discusses the main considerations for the design of an evaluation system for ADM, departing

  18. Catalyzing action towards the sustainability of deltas: deltas as integrated socio-ecological systems and sentinels of regional and global change

    Science.gov (United States)

    Foufoula-Georgiou, E.; Tessler, Z. D.; Brondizio, E.; Overeem, I.; Renaud, F.; Sebesvari, Z.; Nicholls, R. J.; Anthony, E.

    2016-12-01

    Deltas are highly dynamic and productive environments: they are food baskets of the world, home to biodiverse and rich ecosystems, and they play a central role in food and water security. However, they are becoming increasingly vulnerable to risks arising from human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. Our Belmont Forum DELTAS project (BF-DELTAS: Catalyzing actions towards delta sustainability) encompasses an international network of interdisciplinary research collaborators with focal areas in the Mekong, Ganges Brahmaputra, and the Amazon deltas. The project is organized around five main modules: (1) developing an analytical framework for assessing delta vulnerability and scenarios of change (Delta-SRES), (2) developing an open-acess, science-based integrative modeling framework for risk assessment and decision support (Delta-RADS), (3) developing tools to support quantitative mapping of the bio-physical and socio-economic environments of deltas and consolidate bio-physical and social data within shared data repositories (Delta-DAT), (4) developing Global Delta Vulnerability Indices (Delta-GDVI) that capture current and projected scenarios for major deltas around the world , and (5) collaborating with regional stakeholders to put the science, modeling, and data into action (Delta-ACT). In this talk, a research summary will be presented on three research domains around which significant collaborative work was developed: advancing biophysical classification of deltas, understanding deltas as coupled socio-ecological systems, and analyzing and informing social and environmental vulnerabilities in delta regions.

  19. A Conceptual Framework for Analyzing Deltas as Coupled Social-Ecological Systems: An example from the Amazon Delta

    Science.gov (United States)

    Brondizio, E.; Vogt, N. D.; Hetrick, S.; da Costa, S. M. F.; Anthony, E.

    2015-12-01

    At the nexus of watersheds, land, coastal areas, oceans, and human settlements, river delta regions pose specific challenges to environmental governance and sustainability. Using the Amazon Delta (AD) as our focus we reflect on the challenges created by the high degree of functional interdependencies shaping social-ecological dynamics of delta regions. The article introduces the initial design of an integrated conceptual framework to analyze delta regions as coupled social-ecological systems (SES). The first component of the framework is used to provide integrated definitions of delta regions according to a problem and/or collective action dilemma. Five different systematic components are suggested: social-economic systems, governance systems, ecosystems-resource systems, topographic-hydrological systems, and oceanic-climate systems. The second component of the framework presents a strategy for nested social ecological analysis to examine collective action situations in delta regions from local to regional and basin levels. The article provides illustrative applications of the framework to the Amazon Delta. First, it is used to define the AD region as a coupled, multi-level SES. We further proposed a definition of what we call the core SES of the AD. We then utilize the framework to diagnose an example collective action problem related to the impacts of urban growth and pollution on small-scale fishing resources. We argue that the functional interdependencies characteristic of delta regions require new approaches to understand, diagnose, and evaluate the current and future impact of social and environmental changes and potential solutions to the sustainability dilemmas characteristic of these regions.

  20. Delta-Complete Analysis for Bounded Reachability of Hybrid Systems

    Science.gov (United States)

    2014-07-16

    system models that arise in biomedical and robotics applications. This research was sponsored by the National Science Foundation grants no. CNS1330014...biomedical and robotics applications. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF...ODEs #Vars Delta Result Time(s) Trace AF-GOOD 4 3 20 53 0.001 SAT 0.425 793K AF-BAD 4 3 20 53 0.001 UNSAT 0.074 — AF-TO1-GOOD 4 3 24 62 0.001 SAT 2.750

  1. The Study of Switching Overvoltages under Power System Restoration Scenario Using Extended Delta-Bar-Delta Algorithm

    Science.gov (United States)

    Sadeghkhani, Iman; Ketabi, Abbas; Feuillet, Rene

    2013-06-01

    This paper presents an intelligent approach to evaluate switching overvoltages during power equipment energization. Switching action is one of the most important issues in power system restoration schemes. This action may lead to overvoltages that can damage some equipment and delay power system restoration. In this work, transient overvoltages caused by power equipment energization are analyzed and estimated using artificial neural network (ANN)-based approach. Three learning algorithms, delta-bar-delta (DBD), extended delta-bar-delta (EDBD), and directed random search (DRS), were used to train the ANNs. In the cases of transformer and shunt reactor energization, ANNs are trained with the worst case scenario of switching angle and remanent flux which reduce the number of required simulations for training ANN. Also, for achieving good generalization capability for developed ANN, equivalent parameters of the network are used as ANN inputs. The simulated results for a partial of 39-bus New England test system, show that the proposed technique can estimate the peak values and duration of switching overvoltages with good accuracy and EDBD algorithm presents best performance.

  2. Integrating millennial and interdecadal shoreline changes: Morpho-sedimentary investigation of two prograded barriers in southeastern Australia

    Science.gov (United States)

    Oliver, T. S. N.; Tamura, T.; Hudson, J. P.; Woodroffe, C. D.

    2017-07-01

    Prograded barriers are distinctive coastal landforms preserving the position of past shorelines as low relief, shore-parallel ridges composed of beach sediments and commonly adorned with variable amounts of dune sand. Prograded barriers have been valued as coastal archives which contain palaeoenvironmental information, however integrating the millennial timescale geological history of barriers with observed inter-decadal modern beach processes has proved difficult. Technologies such as airborne LiDAR, ground penetrating radar (GPR) and optically stimulated luminescence dating (OSL) were utilised at Boydtown and Wonboyn, in southeastern Australia, and combined with previously reported radiocarbon dates and offshore seismic and sedimentological data to reconstruct the morpho-sedimentary history of prograded barrier systems. These technologies enabled reconstruction of geological timescale processes integrated with an inter-decadal model of ridge formation explaining the GPR-imaged subsurface character of the barriers. Both the Boydtown and Wonboyn barriers began prograding 7500-8000 years ago when sea level attained at or near present height along this coastline and continued prograding until the present-day with an initially slower rate of shoreline advancement. Sources of sediment for progradation appear to be the inner shelf and shoreface with a large shelf sand body likely contributing to progradation at Wonboyn. The Towamba River seems to have delivered sediment to Twofold Bay during flood events after transitioning to a mature estuarine system sometime after 4000 cal. yr BP. Some of this material appears to have been reworked onto the Boydtown barrier, increasing the rate of progradation in the seaward 50% of the barrier deposited over the past 1500 years. The GPR imaged beachfaces are shown to have similar geometry to beach profiles following recent storm events and a model of ridge formation involving cut and fill of the beachface, and dune building in the

  3. Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

    Science.gov (United States)

    Nienhuis, Jaap H.; Ashton, Andrew D.; Kettner, Albert J.; Giosan, Liviu

    2017-09-01

    The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal) dynamics or allogenic (external) forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

  4. Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

    Directory of Open Access Journals (Sweden)

    J. H. Nienhuis

    2017-09-01

    Full Text Available The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal dynamics or allogenic (external forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

  5. Chlorine isotope behavior during prograde metamorphism of sedimentary rocks

    Science.gov (United States)

    Selverstone, Jane; Sharp, Zachary D.

    2015-05-01

    Chlorine stable isotope compositions of two sedimentary sequences and their metamorphic equivalents were measured in order to study fractionation effects during prograde metamorphism and devolatilization. Protoliths (n = 25) were collected from a 50 m section of Triassic fluvial and playa-lake strata and Jurassic (Liassic) marine black shales in a well-characterized quarry. Low greenschist to middle amphibolite facies equivalents (n > 80) were collected from the Glarus Alps, Urseren Zone, and Lucomagno region. Bulk δ37Cl values are constant within individual sedimentary layers, but vary from -2.0 to + 2.4 ‰ in Triassic rocks and from -3.0 to 0‰ in the black shales. Dolomitic and gypsiferous samples have positive δ37Cl values, but marls and shales are isotopically negative. Bulk Cl contents show only small declines during the earliest stages of metamorphism. Metamorphic equivalents of the Triassic and Liassic protoliths record the same overall ranges in δ37Cl as their protoliths. Samples with highly correlated bulk compositions but different metamorphic grade show no statistically significant difference in δ37Cl. These data lead to the following conclusions: (1) Terrestrial and marine sedimentary rocks display large primary heterogeneities in chlorine isotope composition. As a result, an unambiguous "sedimentary signature" does not exist in the chlorine stable isotope system. (2) No isotopic fractionation is discernable during metamorphic devolatilization, even at low temperatures. Alpine-style metamorphism thus has little to no effect on bulk chlorine isotopic compositions, despite significant devolatilization. (3) Cl is largely retained in the rocks during devolatilization, contrary to the normally assumed hydrophilic behavior of chlorine. Continuous release of mixed-volatile C-O-H fluids likely affected Cl partitioning between fluid and minerals and allowed chlorine to remain in the rocks. (4) There is no evidence for fluid communication across (meta

  6. Peat or no peat: Why do the Rajang and Mahakam Deltas differ?

    Energy Technology Data Exchange (ETDEWEB)

    Gastaldo, Robert A. [Department of Geology, Colby College, 5807 Mayflower Hill Drive, Waterville, ME 04901 (United States)

    2010-08-01

    Coastal and deltaic Holocene peat accumulations around the equatorial island of Borneo, Southeast Asia, have served as models for economic coal-bearing sequences in the stratigraphic record. Although climatic conditions, vegetational communities, and sedimentary regimes are comparable, peat accumulations are not found on both the western and eastern sides of the island. The Rajang River delta and coastal plain, Sarawak, East Malaysia, are covered in areally extensive, thick peat deposits that have attained at least a thickness of > 13 m in ombrogenous peat domes (Marudi, Baram River). Peat-swamp biomass began to accumulate over Pleistocene podzols when sea level stabilized {proportional_to} 7.5 ka and delta progradation was initiated. The Mahakam River delta and coastal plain, East Kalimantan, Indonesia, also began progradation at this time, but there is no evidence in any part of the coastal region for peat accumulation. Rather, poorly developed organic-rich gleysols occur throughout the delta plain. Both the Rajang River and Mahakam River deltas are tidally influenced, fine-grained systems, with a sediment provenance in the Central Massif. Sediment transported through the Rajang River delta differs in that as much as 60% of the clay minerals deposited in the system are mixed layer (I/S) and expandable (K/E) clays that act to restrict pore water flow in the tidal and overbank deposits that comprise the delta plain. These result in the development of an aquiclude above which paludal conditions develop, promoting accumulation of organic matter. In contrast, there is a low proportion of mixed layer and expandable clays transported in the Mahakam River system. This precludes the development of a stilted water table within the delta, allowing for organic matter recycling without peat accumulation. The presence of a high proportion of expandable clay minerals on the western side of Borneo is a reflection of the weathering and eroding source rocks on this side of the

  7. Cases Studies of Irrigated Soil Degradation and Progradation

    Science.gov (United States)

    Zeyliger, Anatoly; Kust, German; Rozov, Sergey; Stoma, Galina

    2013-04-01

    Waterlogging and salination, along with interaction with other degradation processes, have not only caused the collapse of irrigation-based societies in the past, but are indeed threatening the viability of irrigation at present. The problem is global in scope. Decimation of natural ecosystems, deterioration of soil productivity depletion and pollution of water resources, and conflicts over dwindling supplies have become international problems closely linked with extension of irrigation development to large scale and associated impact to soil fertility and surrounding environment. Practical experience and scientific research done in the frame of FP6 DESIRE project provided an affirmative answer to the question - can irrigated agriculture be sustained for long time. In present contribution two case studies will be discussed and analysed in scope to compare different irrigation practises used for about 35 years and their impact to soil fertility. Investigated areas of both case studies are situated in the same Saratov Region of Russia at the left bank of middle part of Volga River with distance between about 100 km. First case study was developed during 2009-2010 by field trials at irrigated and surrounded areas of agricultural farms situated at Privolghskaya Irrigation System (Marksovsky District). Second case study was developed during summer of 2011 by field trial at experimental farm of research institute called VolgNIIGiM (Enghelsky District). During fields trail soil maps of both case studies were developed and compared with soil maps of the same areas done at 1970th before irrigation projects at both areas were started. Results of soil map comparison are showing that in the territory of first case study considerable soil degradation is taken place, but in the territory of the second case study a substantial soil progradation is taken place. Thus is supported by the time series of ground water monitoring at both irrigated areas. Obtained results will be

  8. 'Storm-flood' coastal systems in relation to delta front-shoreface facies models: applications to Miocene successions in the Baram Delta Province, NW Borneo

    Science.gov (United States)

    Collins, Daniel; Johnson, Howard; Allison, Peter

    2015-04-01

    that commonly define the bases of these beds. These features are uniquely abundant throughout the study area and display both exceptionally large dimensions, with thicknesses up to 2 m and widths >10 m, and a wide range of geometries. Isolated gutter casts, often up to 1-2 m deep, occur with steep to overhanging walls. The abundance, dimensions and wide-variability of gutter casts observed is unlike those documented in traditional wave-dominated shoreline successions and also attests to high-energy, erosive storm-flood flows with large sediment supply. We suggest the basinward progradation, coalescence of several small delta fronts, which may show updrift versus downdrift asymmetry, are responsible for a 'ragged blanket' of river-bypassed sand. Subsequent marine reworking may increase lateral sand continuity resulting in more typical 'shoreface-like' successions.

  9. Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

    Science.gov (United States)

    Flocks, James G.; Kindinger, Jack G.; Ferina, Nicholas; Dreher, Chandra

    2002-01-01

    The Mississippi and Atchafalaya Rivers transport very large amounts of bedload and suspended sediments to the deltaic and coastal environments of the northern Gulf of Mexico. Absorbed onto these sediments are contaminants that may be detrimental to the environment. To adequately assess the impact of these contaminants it is first necessary to develop an understanding of sediment distribution patterns in these deltaic systems. The distribution patterns are defined by deltaic progradational cycles. Once these patterns are identified, the natural and industrial contaminant inventories and their depositional histories can be reconstructed. Delta progradation is a function of sediment discharge, as well as channel and receiving-basin dimensions. Fluvial energy controls the sediment distribution pattern, resulting in a coarse grained or sandy framework, infilled with finer grained material occupying the overbank, interdistributary bays, wetlands and abandoned channels. It has been shown that these fine-grained sediments can carry contaminants through absorption and intern them in the sediment column or redistribute them depending on progradation or degradation of the delta deposit. Sediment distribution patterns in delta complexes can be determined through high-resolution geophysical surveys and groundtruthed with direct sampling. In the Atchafalaya and Mississippi deltas, remote sensing using High-Resolution Single-Channel Seismic Profiling (HRSP) and Sidescan Sonar was correlated to 20-ft vibracores to develop a near-surface geologic framework that identifies variability in recent sediment distribution patterns. The surveys identified bedload sand waves, abandoned-channel back-fill, prodelta and distributary mouth bars within the most recently active portions of the deltas. These depositional features respond to changes in deltaic processes and through their response may intern or transport absorbed contaminants. Characterizing these features provides insight into the

  10. Prominence of gamma delta T cells in the ruminant immune system.

    Science.gov (United States)

    Hein, W R; Mackay, C R

    1991-01-01

    The lymphoid systems of sheep and cattle contain a large number of gamma delta T cells, in striking contrast to the lymphoid systems of humans and mice. In neonatal animals particularly, these cells comprise the predominant fraction of T cells in the blood. Here Wayne Hein and Charles Mackay discuss what is currently known about the ontogeny, phenotype, tissue distribution and function of gamma delta T cells in ruminants. There are a number of interesting molecular features that characterize ruminant gamma delta T cells, but these do not entirely explain the high frequency of use of the gamma delta T-cell receptor in these animals. Studies on sheep, cattle or other animals that preferentially use gamma delta T cells should provide insights into the biological significance of the existence of two distinct forms of the T-cell receptor.

  11. Retrograde versus Prograde Models of Accreting Black Holes

    Directory of Open Access Journals (Sweden)

    David Garofalo

    2013-01-01

    Full Text Available There is a general consensus that magnetic fields, accretion disks, and rotating black holes are instrumental in the generation of the most powerful sources of energy in the known universe. Nonetheless, because magnetized accretion onto rotating black holes involves both the complications of nonlinear magnetohydrodynamics that currently cannot fully be treated numerically, and uncertainties about the origin of magnetic fields that at present are part of the input, the space of possible solutions remains less constrained. Consequently, the literature still bears witness to the proliferation of rather different black hole engine models. But the accumulated wealth of observational data is now sufficient to meaningfully distinguish between them. It is in this light that this critical paper compares the recent retrograde framework with standard “spin paradigm” prograde models.

  12. Holocene evolution of the Liaohe Delta, a tide-dominated delta formed by multiple rivers in Northeast China

    Science.gov (United States)

    He, Lei; Xue, Chunting; Ye, Siyuan; Laws, Edward Allen; Yuan, Hongming; Yang, Shixiong; Du, Xiaolei

    2018-02-01

    The Liaohe Delta in Northeast China is one of the ecologically important estuarine deltas in China. It has been formed via the accumulation of sediment discharged by four rivers in the Liaohe Plain that enter Liaodong Bay. Twenty-seven 30-40 m long cores recovered from the Liaohe Plain and Liaodong Bay were analyzed for sedimentary characteristics, grain size, foraminifera species, and ages determined by accelerator mass spectrometry (AMS) 14C to document the stratigraphical sequence and the spatio-temporal evolution of the Liaohe Delta. Our results revealed that the sedimentary environments have evolved from fluvial, tidal flat/estuarine, to neritic and finally to a deltaic environment since the Late Pleistocene. The Holocene transgression arrived at the present coastline at ∼8500 cal a BP and flooded the maximum area of land at ∼7000 cal a BP. A deltaic environment prevailed in this area after 7000 cal a BP. Bounded by the modern Liaohe River mouth, the present deltaic sedimentary system can be divided into the eastern and western components. The rate of seaward progradation of the eastern paleocoastline was estimated to be ∼8.6 m/a since 7000 cal a BP; the eastern cores in the present coastline began receiving the deltaic sediments at ∼5000 cal a BP. The rate of seaward progradation of the western paleocoastline was estimated to be only ∼2.8 m/a since 7000 cal a BP. The coastline on the western side began accumulating deltaic sediments about 2000 years later than the eastern coastline. Depocenter shifting was hypothesized to be the reason for the spatial differences in the sedimentary processes. However, the change of sediment fluxes of the western rivers due to climate changes and ancient human impacts might be the reason for the differences of the temporal evolution of the eastern and western sedimentary systems in the Liaohe Delta.

  13. Comparison of tillage systems for paddy rice in the Mekong Delta of Vietnam

    NARCIS (Netherlands)

    Nguyen, V.L.; Hoogmoed, W.B.; Perdok, U.D.

    2007-01-01

    In the Mekong delta of Vietnam, wetland rice is the main crop. The traditional rice cropping system with one crop per year changed to a system with two or three crops per year, and mechanised tillage replaced traditional tillage by water buffaloes. Currently, three tillage systems can be

  14. Design and study of the mask exchange system based on Delta parallel mechanism

    Science.gov (United States)

    Zhang, Feifan; Wang, Jianping; Zhou, Hongfei; Zhou, Zengxiang; Chu, Jiaru

    2016-07-01

    Mask exchange system is the main part of Multi-Object Broadband Imaging Echellette (MOBIE) on the Thirty Meter Telescope (TMT). The robot is one of the key parts in the mask exchange process. In view of the facts that the scheme the on-board robot is hard to meet the requirements of TMT and the traditional industrial robot is difficult to use in the Mask Exchange System (MEX). The delta parallel mechanism has much advantages such as good dynamic performance, high speed and could integrate a vision recognition system to identify the masks. The design for MEX based on off-board Delta parallel mechanism was proposed in the paper.

  15. Factors affecting farmers' adoption of integrated rice-fish farming systems in the Mekong delta, Vietnam

    NARCIS (Netherlands)

    Bosma, R.H.; Nhan, D.K.; Udo, H.M.J.; Kaymak, U.

    2012-01-01

    This study investigated the determinants of the adoption of improved rice–fish farming systems in the Mekong delta to support policy making, agricultural land-use planning and extension of integrated rice–fish farming. Recently these systems have been referred to as adaptations to climate change,

  16. Integrated agriculture-aquaculture systems in the Mekong Delta, Vietnam: an analysis of recent trends

    NARCIS (Netherlands)

    Thanh Phong, Le; Udo, H.M.J.; Mensvoort, van M.E.F.; Bosma, R.H.; Quang Tri, Le; Nhan, D.K.; Zijpp, van der A.J.

    2008-01-01

    In order to explain the trends in the development and farm attributes of Integrated Agriculture-Aquaculture (IAA) systems in the Mekong Delta of Vietnam, a participatory community appraisal and two surveys are carried out in three districts with contrasting fish culture input systems. The first

  17. The morphodynamic significance of rapid shoreline progradation followed by vertical foredune building at Pedro Beach, southeastern Australia

    Science.gov (United States)

    Oliver, Thomas; Tamura, Toru; Short, Andrew; Woodroffe, Colin

    2017-04-01

    Prograded coastal barriers are accumulations of marine and aeolian sands configured into shore-parallel ridges. A variety of ridge morphologies described around the world reflect differences in origin as a consequence of differing prevailing coastal morphodynamics. The 'morphodynamic approach' described by Wright and Thom (1977) expounds the coastal environmental conditions, hydrodynamic and morphodynamic processes and inheritance of evolutionary sequences over varying temporal scales which interdependently operate to produce an assemblage of coastal landforms adjusted, or adjusting to, a dynamic equilibrium. At Pedro Beach on the southeastern coast of Australia a large sandy deposit of foredune ridges provides an opportunity to explore the morphodynamic paradigm as it applies to coastal barrier systems using optically stimulated luminescence (OSL) dating, ground penetrating radar (GPR) and airborne LiDAR topography. The prograded barrier at Pedro Beach has formed following the stabilisation of the sea level at its present height on the southeast Australian coastline. A series of dune-capped ridges, increasing in height seawards, formed from 6000 years ago to 4000 years ago. During this time the shoreline straightened as bedrock accommodation space for Holocene sediments diminished. Calculation of Holocene sediment volumes utilising airborne LiDAR topography shows a decline in sediment volume over this time period coupled with a decrease in shoreline progradation rate from 0.75 m/yr to 0.49 m/yr. The average ridge 'lifetime' during this period increases resulting in higher ridges as dune-forming processes have longer to operate. Greater exposure to wave and wind energy also appears to have resulted in higher ridges as the sheltering effect of marginal headlands has diminished. A high outer foredune has formed through vertical accretion in the past 700 years, evidenced by GPR subsurface structures and upward younging of OSL ages, with a sample from 1 m deep within

  18. Delta III—an evolutionary delta growth

    Science.gov (United States)

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

    1996-03-01

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

  19. Sea-Level Rise and Land Subsidence in Deltas: Estimating Future Flood Risk Through Integrated Natural and Human System Modeling

    Science.gov (United States)

    Tessler, Z. D.; Vorosmarty, C. J.

    2016-12-01

    Deltas are highly sensitive to local human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. We present a new delta flood exposure and risk framework for estimating the sensitivity of deltas to relative sea-level rise. We have applied this framework to a set of global environmental, geophysical, and social indicators over 48 major river deltas to quantify how contemporary risks vary across delta systems. The risk modeling framework incorporates upstream sediment flux and coastal land subsidence models, global empirical estimates of contemporary storm surge exposure, and population distribution and growth. Future scenarios are used to test the impacts on coastal flood risk of upstream dam construction, coastal population growth, accelerated sea-level rise, and enhanced storm surge. Results suggest a wide range of outcomes across different delta systems within each scenario. Deltas in highly engineered watersheds (Mississippi, Rhine) exhibit less sensitivity to increased dams due to saturation of sediment retention effects, though planned or under-construction dams are expected to have a substantial impact in the Yangtze, Irrawaddy, and Magdalena deltas. Population growth and sea-level rise are expected to be the dominant drivers of increased human risk in most deltas, with important exceptions in several countries, particularly China, where population are forecast to contract over the next several decades.

  20. The power-efficient biomedical acquisition system by variable-resolution sigma-delta modulator.

    Science.gov (United States)

    Hsu, Chen-Ming; Wang, Wei-Song; Luo, Ching Hsing

    2007-01-01

    A novel biomedical acquisition system which can adjust its resolution by the condition of signal is presented in this paper. The resolution of sigma-delta modulator in proposed system can be automatically varied by switching its architecture and sampling rate that can acquire accurate date without additional power consumption. The modulator in this system reaches specifications from 10-bit to 16-bit resolution and consumes power from 48microW to 360microW. In the electrocardiogram and electroculogram acquisition by proposed system, it can save more than 40% and 73% power consumption comparing with the conventional acquisition system.

  1. Delta robot

    NARCIS (Netherlands)

    Herder, J.L.; Van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at

  2. Mechanism of {delta}'-phase formation in Al-Li and Al-Li-Mg systems alloys

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.A.; Lukina, E.A.; Ermolova, M.I. [All-Russian Inst. of Aviation Materials (VIAM), Moscow (Russian Federation); Khokhlatova, L.B.

    2002-07-01

    In the given work the 1424 alloy of Al-Li-Mg system (Al-1.61%Li-5.6%Mg+additions) was investigated in the ageing temperature range from 20 C to 200 C. It is shown the presence of precipitates of the non-equilibrium {delta} (AlLi)-phase. This phase is called as {delta}{sub non}-phase. It was also found a new type of solid solution decomposition in Al-Li-Mg-alloys, presumably, with {beta}'(Al{sub 5}Mg{sub 8})-phase formation. Regions of the presence of new phases are shown an TTT diagram. It was established that in the process of ageing a fine-grained cellular structure is formed around the particles of {delta}{sub non}-phase. The models of {delta}' and {delta}{sub non}-phases precipitates structure were developed. (orig.)

  3. Design of lipid-based delivery systems for improving lymphatic transport and bioavailability of delta-tocopherol and nobiletin

    Science.gov (United States)

    Xia, Chunxin

    Lymphatic drug transport can confer bioavailability advantage by avoiding the first-pass metabolism normally observed in the portal vein hepatic route. It was reported that long chain lipid-based delivery systems can stimulate the formation of chylomicron and thus promote the lymphatic transport of drugs. In this study, a novel delta-tocopherol (delta-T) loaded Solid Lipid Nanoparticle (SLN) system was developed to investigate its effect on promoting the lymphatic transport of delta-T. The delta-T SLN was prepared with hot melt emulsification method by using glyceryl behenate (compritol RTM888) as the lipid phase and lecithin (PC75) as the emulsifier. Formula configuration, processing condition and loading capacity were carefully optimized. Physicochemical properties (particle size, surface charge, morphology) were also characterized. Moreover, excellent stability of the developed delta-T SLN in the gastrointestinal environment was observed by using an in vitro digestion model. Further investigations of the SLN in stimulating delta-T lymphatic transport were performed on mice without cannulation. Compared with the control group (delta-T corn oil dispersion), much lower delta-T levels in both blood and liver indicated reduced portal vein and hepatic transport of delta-T in the form of SLN. On the other hand, significantly higher concentrations of delta-T were observed in thymus, a major lymphatic tissue, indicating improved lymphatic transport of delta-T with the SLN delivery system. Finally, the far less excreted delta-T level in feces further confirmed improved lymphatic transport and overall bioavailability of delta-T by using SLN system. Nobiletin (NOB), one of most abundant polymethoxyflavones (PMFs) found in Citrus genus, has a low solubility in both water and oil at ambient temperatures. Thus it tends to form crystals when the loading exceeds its saturation level in the carrier system. This character greatly impaired its bioavailability and application. To

  4. Digital TV tri-state delta modulation system for Space Shuttle ku-band downlink

    Science.gov (United States)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    1982-01-01

    A tri-state delta modulation/demodulation (TSDM) technique which provides for efficient run-length coding of constant-intensity segments of a TV picture is described. Aspects of the hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV or field-sequential color or NTSC format color are reviewed. Run-length encoding of the TSDM output can consistently reduce the required channel data rate well below one bit per sample. As compared with a bistate delta modulation system, the present technique eliminates granularity in the reconstructed video without degrading rise or fall times. About 40 chips are used by TSDM when used to handle the luminance information in a color link. A possible overall space and ground functional configuration to accommodate Shuttle digital TV with scrambling for privacy is presented.

  5. Digital TV tri-state delta modulation system for Space Shuttle ku-band downlink

    Science.gov (United States)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    A tri-state delta modulation/demodulation (TSDM) technique which provides for efficient run-length coding of constant-intensity segments of a TV picture is described. Aspects of the hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV or field-sequential color or NTSC format color are reviewed. Run-length encoding of the TSDM output can consistently reduce the required channel data rate well below one bit per sample. As compared with a bistate delta modulation system, the present technique eliminates granularity in the reconstructed video without degrading rise or fall times. About 40 chips are used by TSDM when used to handle the luminance information in a color link. A possible overall space and ground functional configuration to accommodate Shuttle digital TV with scrambling for privacy is presented.

  6. [Application of over sampling sigma-delta A/D in DOAS system].

    Science.gov (United States)

    Li, Su-wen; Liu, Wen-qing; Xie, Pin-hua

    2006-12-01

    Differential optical absorption spectroscopy (DOAS) has become a widely used method to measure trace gases in the atmosphere. Concentration of trace gases is retrieved using least-squares fits of reference spectra to the measurement spectra. The measurement precision not only depends on the measurement precision of spectra and the noise of instrument and disturbing of other gases in measuring band, but suffers the influence of signal sampling and pre-processing. The present paper simply introduced DOAS measuring principle and the setup of instrument and put forward improving method-the technology of over sampling sigma- deltaA/D. Using the sigma-delta modulator structure to shape noises together with the over sampling technology can doubly restrain quantifying noises, which can improve the signal-to-noise ratio within the measuring band. So the measurement precision of DOAS system is improved with this technology.

  7. Spatio-temporal patterns and predictions of phytoplankton assemblages in a subtropical river delta system

    DEFF Research Database (Denmark)

    Wang, Chao; Li, Xinhui; Wang, Xiangxiu

    2016-01-01

    Spatial and seasonal sampling within a subtropical river delta system, the Pearl River Delta (China), provided data to determine seasonal phytoplankton patterns and develop prediction models. The high nutrient levels and frequent water exchanges resulted in a phytoplankton community with greatest...... diversity of Bacillariophyceae and Chlorophyceae, and greatest biomass of Bacillariophyceae. Spatial and temporal distributions of phytoplankton assemblages were revealed using non-metric multidimensional scaling (NMDS). Five groups were established using hierarchical clustering based on species biomass...... similarities. These groups were distinct with respect to species richness, biomass and indicators, especially for groups representing spatial dimension. The Linear Discriminant Analysis (LDA) model indicated that the spatial patterns of phytoplankton assemblages were mostly explained by water quality variables...

  8. Variability Matters: New Insights into Mechanics of River Avulsions on Deltas and Their Deposits

    Science.gov (United States)

    Ganti, V.

    2015-12-01

    River deltas are highly dynamic, often fan-shaped depositional systems that form when rivers drain into a standing body of water. They host over a half billion people and are currently under threat of drowning and destruction by relative sea-level rise, subsidence, and anthropogenic interference. Deltas often develop planform fan shapes through avulsions, whereby major river channel shifts occur via "channel jumping" about a spatial node, thus determining their fundamental length scale. Emerging theories suggest that the size of delta lobes is set by backwater hydrodynamics; however, these ideas are difficult to test on natural deltas, which evolve on centennial to millennial timescales. In this presentation, I will show results from the first laboratory delta built through successive deposition of lobes that maintain a constant size that scales with backwater hydrodynamics. The characteristic size of deltas emerges because of a preferential avulsion node that remains fixed spatially relative to the prograding shoreline, and is a consequence of multiple river floods that produce persistent morphodynamic river-bed adjustment within the backwater zone. Moreover, river floods cause erosion in the lowermost reaches of the alluvial river near their coastline, which may leave erosional boundaries in the sedimentary record that may appear similar to those previously interpreted to be a result of relative sea-level fall. I will discuss the implications of these findings in the context of sustainability management of deltas, decoding their stratigraphic record, and identifying ancient standing bodies of water on other planets such as Mars. Finally, I will place this delta study in a broader context of recent work that highlights the importance of understanding and quantifying variability in sedimentology and geomorphology.

  9. Heavy Metals and Biogenic Elements in Aquatic Systems of the Don River Delta

    Science.gov (United States)

    Tkachenko, Anna; Tkachenko, Oleg

    2014-05-01

    River deltas are located in the lower parts of the cascade landscape-geochemical systems of the river basins, so their geochemical conditions often characterize the anthropogenic impact on whole river system. The Don River runs through the one of the most agriculturally developed and densely populated area of Russia, and flows into the Azov Sea - the smallest and shallowest sea in the world. These factors determine the geochemical features of aquatic systems of the Don River mouth area and the specificity of the "river-sea" geochemical barrier zone. The paper presents results of the field studies of the geochemical structure of the Don River mouth area, which were conducted in frames of the RFBR project in 2012-2013. Major types of the deltaic water streams and bodies were studied in different hydrological seasons: spring floods, summer, autumn and winter low water periods. About 50 samples of water, suspended matter and 60 samples of bottom sediments have been collected and analyzed for heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Pb, Cr, Cd etc.) and biogenic elements (nitrate, nitrite, ammonium, phosphates, silica, total nitrogen and phosphorus, dissolved oxygen and chlorophyll) content. To assess the toxicity degree and nutrient potential of water, bioassay test conducted by growing daphnia in water samples were held. The study shows that the Don River delta water is characterized by the relatively low values of dissolved heavy metal content. Significantly higher values of heavy metals were determined in the vicinity of settlements only. Metal accumulation in bottom sediments can be associated mainly with the rate of water flow. Higher values were found in sediments of small channels with weak flow velocity and prevailing processes of the suspended matter deposition. The data on the seasonal dynamics of nutrients and spatial variability of their forms have been obtained. The maximum concentration of nitrogen, phosphorus, silicon, and other biogenic elements are

  10. Delta Robot

    OpenAIRE

    Herder, J.L.; van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at least one pantograph has a first free extremity (10) at which it supports a countermass (13) which is arranged to balance the center of mass of the robot.

  11. Morphodynamics of the Pacific and Caribbean deltas of Colombia, South America

    Science.gov (United States)

    Restrepo, Juan D.; López, Sergio A.

    2008-02-01

    This paper analyzes the physical factors controlling the recent morphology of major deltas along the Pacific and Caribbean coasts of Colombia. The study considers the fluvial, coastal, and oceanographic contributions to changes in delta morphology and uses different approaches, including (1) remote sensing techniques; (2) time series analysis of river discharge, sea level, wave climate and tidal variability; (3) analysis of the relationship between monthly mean sea level anomalies near the deltas related to the El Niño Southern Oscillation (ENSO); (4) development of a database of key physical variables; (5) series of correlation calculations to examine which environmental factors control delta morphology; (6) analysis of shoreline changes for the 1986-2000 yr-period; and (7) classification of each delta system based on the relationship between water and sediment discharges and wave and tidal energies. Overall, Colombian deltas are built under destructive physical conditions. The Pacific deltas, San Juan, Mira, and Patía, are tide-influenced deltas although they exhibit definite characteristics of wave-dominated systems such as the presence of barriers and beach ridges. Also, these deltas exhibit the highest marine energy conditions of all Colombian deltas (marine power values between 9.1 and 11.6) due to the interplay of (1) moderate wave conditions as a result of the effect of swells from the SW with a significant height varying from 1.7 in the San Juan delta to 3.0 m and 3.1 m in the Mira and Patía deltas, respectively; (2) meso-tidal ranges; (3) steep subaqueous profiles; (4) low attenuation indexes of deep-water waves; and (5) strong oceanographic manifestations associated with the ENSO, causing regional sea level rises of 20-44 cm during El Niño events. The Caribbean deltas, Magdalena, Sinú and to a lesser extent, the Atrato, are wave-influenced deltas. The Magdalena, with deep and nearshore wave power values of 45 × 10 6 erg s -1 and 35 × 10 6 erg s -1

  12. The Semantics of Ada Access Types (Pointers) in the State Delta Verification System (SVDS).

    Science.gov (United States)

    1992-09-30

    AEROSPACE REPORT NO. ATR-92(2778)-5 The Semantics of Ada Access Types (Pointers) in the State Delta Verification System (SVDS) 30 September 1992 LgC...Engineering and Technology Group ". h: is. t ", -.- s -p I SOOPUBLIC RELEASE IS AUTHORIZED 19941214 006 Aerospace Report No. ATR-92(2778)-5 THE SEMANTICS OF ADA...NATIONAL SECURITY AGENCY Ft. George G. Meade, MD 20755-6000 PUBLIC RELEASE IS AUTHORIZED Report No. ATR-92(2778)-5 THE SEMANTICS OF ADA ACCESS TYPES

  13. Heavy metals in system «Delta of Volga - Northern Caspian Sea

    Directory of Open Access Journals (Sweden)

    E. V. Ostrovscaya

    2008-01-01

    Full Text Available It is displayed that the composition of heavy metals compounds in water and suspensions in the area of marine and riverine waters mixing undergo natural changes due to sedimentation and transformation. The system “Volga Delta – North Caspian” as a geochemical barrier hampers the transfer of toxic heavy metals forms from the sea to the river, although the content of toxic iron and manganese forms at the marine border of coastal waters can reach up to 30% of total concentration.

  14. A delta-doped quantum well system with additional modulation doping

    Directory of Open Access Journals (Sweden)

    Luo Dong-Sheng

    2011-01-01

    Full Text Available Abstract A delta-doped quantum well with additional modulation doping may have potential applications. Utilizing such a hybrid system, it is possible to experimentally realize an extremely high two-dimensional electron gas (2DEG density without suffering inter-electronic-subband scattering. In this article, the authors report on transport measurements on a delta-doped quantum well system with extra modulation doping. We have observed a 0-10 direct insulator-quantum Hall (I-QH transition where the numbers 0 and 10 correspond to the insulator and Landau level filling factor ν = 10 QH state, respectively. In situ titled-magnetic field measurements reveal that the observed direct I-QH transition depends on the magnetic component perpendicular to the quantum well, and the electron system within this structure is 2D in nature. Furthermore, transport measurements on the 2DEG of this study show that carrier density, resistance and mobility are approximately temperature (T-independent over a wide range of T. Such results could be an advantage for applications in T-insensitive devices.

  15. Stratigraphy and sedimentology of the Niger Delta

    Science.gov (United States)

    Reijers, T. J. A.

    2011-09-01

    During the Cenozoic, until the Middle Miocene, the Niger Delta grew through pulses of sedimentation over an oceanward-dipping continental basement into the Gulf of Guinea; thereafter progradation took place over a landward-dipping oceanic basement. A 12,000 m thick succession of overall regressive, offlapping sediments resulted that is composed of three diachronous siliciclastic units: the deep-marine pro-delta Akata Group, the shallow-marine delta-front Agbada Group and the continental, delta-top Benin Group. Regionally, sediment dispersal was controlled by marine transgressive/regressive cycles related to eustatic sea-level changes with varying duration. Differential subsidence locally influenced sediment accumulation. Collectively, these controls resulted in eleven chronostratigraphically confined delta-wide mega-sequences with considerable internal lithological variation. The various sea-level cycles were in or out of phase with each other and with local subsidence, and interfered with each other and thus influenced the depositional processes. At the high inflection points of the long-term eustatic sea-level curve, floodings took place that resulted in delta-wide shale markers. At the low inflection points, erosional channels were formed that are often associated, downdip, with turbidites in low-stand sediments (LSTs). The megasequences contain regional transgressive claystone units (TST) followed by a range of heterogeneous fine-to-coarse progradational or aggradational siliciclastic (para)sequence sets formed during sea-level high-stand (HST). An updated biostratigraphic scheme for the Niger Delta is presented. It also updates a sedimentation model that takes into consideration local and delta-wide effects of sea-level cyclicity and delta tectonics. Megasequences were formed over time intervals of ~5 Ma within individual accurate megastructures that laterally linked into depobelts. The megasequences form the time-stratigraphic frame of the delta and are the

  16. Stability and l1-Gain Control of Positive Switched Systems with Time-Varying Delays via Delta Operator Approach

    Directory of Open Access Journals (Sweden)

    Shuo Li

    2013-01-01

    Full Text Available This paper investigates the problems of stability and l1-gain controller design for positive switched systems with time-varying delays via delta operator approach. The purpose is to design a switching signal and a state feedback controller such that the resulting closed-loop system is exponentially stable with l1-gain performance. Based on the average dwell time approach, a sufficient condition for the existence of an l1-gain controller for the considered system is established by constructing an appropriate copositive type Lyapunov-Krasovskii functional in delta domain. Moreover, the obtained conditions can unify some previously suggested relevant methods in the literature of both continuous- and discrete-time systems into the delta operator framework. Finally, a numerical example is presented to explicitly demonstrate the effectiveness and feasibility of the proposed method.

  17. A simple encoding method for Sigma-Delta ADC based biopotential acquisition systems.

    Science.gov (United States)

    Guerrero, Federico N; Spinelli, Enrique M

    2017-10-01

    Sigma Delta analogue-to-digital converters allow acquiring the full dynamic range of biomedical signals at the electrodes, resulting in less complex hardware and increased measurement robustness. However, the increased data size per sample (typically 24 bits) demands the transmission of extremely large volumes of data across the isolation barrier, thus increasing power consumption on the patient side. This problem is accentuated when a large number of channels is used as in current 128-256 electrodes biopotential acquisition systems, that usually opt for an optic fibre link to the computer. An analogous problem occurs for simpler low-power acquisition platforms that transmit data through a wireless link to a computing platform. In this paper, a low-complexity encoding method is presented to decrease sample data size without losses, while preserving the full DC-coupled signal. The method achieved a 2.3 average compression ratio evaluated over an ECG and EMG signal bank acquired with equipment based on Sigma-Delta converters. It demands a very low processing load: a C language implementation is presented that resulted in an 110 clock cycles average execution on an 8-bit microcontroller.

  18. Stratigraphic and structural evolution of the Selenga Delta Accommodation Zone, Lake Baikal Rift, Siberia

    Science.gov (United States)

    Scholz, C.A.; Hutchinson, D.R.

    2000-01-01

    Seismic reflection profiles from the Lake Baikal Rift reveal extensive details about the sediment thickness, structural geometry and history of extensional deformation and syn-rift sedimentation in this classic continental rift. The Selenga River is the largest single source of terrigenous input into Lake Baikal, and its large delta sits astride the major accommodation zone between the Central and South basins of the lake. Incorporating one of the world's largest lacustrine deltas, this depositional system is a classic example of the influence of rift basin structural segmentation on a major continental drainage. More than 3700 km of deep basin-scale multi-channel seismic reflection (MCS) data were acquired during the 1989 Russian and the 1992 Russian–American field programs. The seismic data image most of the sedimentary section, including pre-rift basement in several localities. The MCS data reveal that the broad bathymetric saddle between these two major half-graben basins is underlain by a complex of severely deformed basement blocks, and is not simply a consequence of long-term deltaic deposition. Maximum sediment thickness is estimated to be more than 9 km in some areas around the Selenga Delta. Detailed stratigraphic analyses of the Selenga area MCS data suggest that modes of deposition have shifted markedly during the history of the delta. The present mode of gravity- and mass-flow sedimentation that dominates the northern and southern parts of the modern delta, as well as the pronounced bathymetric relief in the area, are relatively recent developments in the history of the Lake Baikal Rift. Several episodes of major delta progradation, each extending far across the modern rift, can be documented in the MCS data. The stratigraphic framework defined by these prograding deltaic sequences can be used to constrain the structural as well as depositional evolution of this part of the Baikal Rift. An age model has been established for this stratigraphy, by

  19. PermVeg: A model to design crop sequences for permanent vegetable production systems in the Red River Delta, Vietnam

    NARCIS (Netherlands)

    Pham Thi Thu Huong, Huong; Everaarts, A.P.; Berg, van den W.; Neeteson, J.J.; Struik, P.C.

    2014-01-01

    The constraints in current vegetable production systems in the Red River Delta, Vietnam, in which vegetables are rotated with flooded rice, called for the design of alternative systems of permanent vegetable production. The practical model, PermVeg, was developed to generate vegetable crop sequences

  20. Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

    Directory of Open Access Journals (Sweden)

    Chen Qin

    2013-01-01

    Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

  1. Evaluating sustainable adaptation strategies for vulnerable mega-deltas using system dynamics modelling: Rice agriculture in the Mekong Delta's An Giang Province, Vietnam.

    Science.gov (United States)

    Chapman, Alexander; Darby, Stephen

    2016-07-15

    Challenging dynamics are unfolding in social-ecological systems around the globe as society attempts to mitigate and adapt to climate change while sustaining rapid local development. The IPCC's 5th assessment suggests these changing systems are susceptible to unforeseen and dangerous 'emergent risks'. An archetypal example is the Vietnamese Mekong Delta (VMD) where the river dyke network has been heightened and extended over the last decade with the dual objectives of (1) adapting the delta's 18 million inhabitants and their livelihoods to increasingly intense river-flooding, and (2) developing rice production through a shift from double to triple-cropping. Negative impacts have been associated with this shift, particularly in relation to its exclusion of fluvial sediment deposition from the floodplain. A deficit in our understanding of the dynamics of the rice-sediment system, which involve unintuitive delays, feedbacks, and tipping points, is addressed here, using a system dynamics (SD) approach to inform sustainable adaptation strategies. Specifically, we develop and test a new SD model which simulates the dynamics between the farmers' economic system and their rice agriculture operations, and uniquely, integrates the role of fluvial sediment deposition within their dyke compartment. We use the model to explore a range of alternative rice cultivation strategies. Our results suggest that the current dominant strategy (triple-cropping) is only optimal for wealthier groups within society and over the short-term (ca. 10years post-implementation). The model suggests that the policy of opening sluice gates and leaving paddies fallow during high-flood years, in order to encourage natural sediment deposition and the nutrient replenishment it supplies, is both a more equitable and a more sustainable policy. But, even with this approach, diminished supplies of sediment-bound nutrients and the consequent need to compensate with artificial fertilisers will mean that smaller

  2. What Determines Water Temperature Dynamics in the San Francisco Bay-Delta System?

    Science.gov (United States)

    Vroom, J.; van der Wegen, M.; Martyr-Koller, R. C.; Lucas, L. V.

    2017-11-01

    Water temperature is an important factor determining estuarine species habitat conditions. Water temperature is mainly governed by advection (e.g., from rivers) and atmospheric exchange processes varying strongly over time (day-night, seasonally) and the spatial domain. On a long time scale, climate change will impact water temperature in estuarine systems due to changes in river flow regimes, air temperature, and sea level rise. To determine which factors govern estuarine water temperature and its sensitivity to changes in its forcing, we developed a process-based numerical model (Delft3D Flexible Mesh) and applied it to a well-monitored estuarine system (the San Francisco Estuary) for validation. The process-based approach allows for detailed process description and a physics-based analysis of governing processes. The model was calibrated for water year 2011 and incorporated 3-D hydrodynamics, salinity intrusion, water temperature dynamics, and atmospheric coupling. Results show significant skill in reproducing temperature observations on daily, seasonal, and yearly time scales. In North San Francisco Bay, thermal stratification is present, enhanced by salinity stratification. The temperature of the upstream, fresh water Delta area is captured well in 2-D mode, although locally—on a small scale—vertical processes (e.g., stratification) may be important. The impact of upstream river temperature and discharge and atmospheric forcing on water temperatures differs throughout the Delta, possibly depending on dispersion and residence times. Our modeling effort provides a sound basis for future modeling studies including climate change impact on water temperature and associated ecological modeling, e.g., clam and fish habitat and phytoplankton dynamics.

  3. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

    Directory of Open Access Journals (Sweden)

    Ziliang Liu

    Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front

  4. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

    Science.gov (United States)

    Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

    2015-01-01

    A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

  5. Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin.

    Science.gov (United States)

    Micallef, Aaron; Ribó, Marta; Canals, Miquel; Puig, Pere; Lastras, Galderic; Tubau, Xavier

    2013-04-01

    40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins. In this study we analyse multibeam echosounder and seismic reflection data from the southern Ebro margin (western Mediterranean Sea) to document the stages through which a first-order gully develops into a mature, shelf-breaching canyon and, finally, into a canyon-channel system. This morphological evolution allows the application of a space-for-time substitution approach. Initial gully growth on the continental slope takes place via incision and downslope elongation, with limited upslope head retreat. Gravity flows are the main driver of canyon evolution, whereas slope failures are the main agent of erosion; they control the extent of valley widening, promote tributary development, and their influence becomes more significant with time. Breaching of the continental shelf by a canyon results in higher water/sediment loads that enhance canyon development, particularly in the upper reaches. Connection of the canyon head with a paleo-river changes evolution dynamics significantly, promoting development of a channel and formation of depositional landforms. Morphometric analyses demonstrate that canyons develop into geometrically self-similar systems that approach steady-state and higher drainage efficiency. Canyon activity in the southern Ebro margin is pulsating and enhanced during sea level lowstands. Rapid sedimentation by extension of the palaeo-Millars River into the outermost shelf and upper

  6. A Contingency in the Rosetta Reaction Control System: Alternative Cruise Trajectory Strategies to Cope with Degraded Delta-V Resources

    Science.gov (United States)

    Bauske, Rainer; Companys, Vincente

    2007-01-01

    Since August 2006 a pressure transducer of the Rosetta Reaction Control System (RCS) shows anomalous telemetries indicating a possible leak in a pressurant line. The future operation mode of the RCS may be affected by this problem, resulting in performance degradation. The current propellant budget and its future evolution are evaluated to show the possible states w.r.t. the required mission delta-V. Alternative cruise trajectory strategies are analyzed, providing delta-V savings, to compensate for the expected performance loss of the RCS.

  7. Corporate Social Responsibility: Case Study of Community Expectations and the Administrative Systems, Niger Delta

    Science.gov (United States)

    Ogula, David

    2012-01-01

    Poor community-company relations in the Niger Delta have drawn attention to the practice of corporate social responsibility (CSR) in the region. Since the 1960s, transnational oil corporations operating in the Niger Delta have adopted various CSR strategies, yet community-company relations remain adversarial. This article examines community…

  8. 30 CFR 77.703 - Grounding frames of stationary high-voltage equipment receiving power from ungrounded delta systems.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding frames of stationary high-voltage equipment receiving power from ungrounded delta systems. 77.703 Section 77.703 Mineral Resources MINE SAFETY..., SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.703 Grounding frames of...

  9. 30 CFR 75.704 - Grounding frames of stationary high-voltage equipment receiving power from ungrounded delta systems.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding frames of stationary high-voltage equipment receiving power from ungrounded delta systems. 75.704 Section 75.704 Mineral Resources MINE SAFETY...-UNDERGROUND COAL MINES Grounding § 75.704 Grounding frames of stationary high-voltage equipment receiving...

  10. Immunohistochemical observations of methionine-enkephalin and delta opioid receptor in the digestive system of Octopus ocellatus.

    Science.gov (United States)

    Sha, Ailong; Sun, Hushan; Wang, Yiyan

    2013-02-01

    The study was designed to determine whether methionine-enkephalin (met-Enk) or delta opioid receptor was present in the digestive system of Octopus ocellatus. The results showed that they were both in the bulbus oris, esophagus, crop, stomach, gastric cecum, intestine, posterior salivary glands of O. ocellatus, one of them, met-Enk in the rectum, anterior salivary glands, digestive gland. And the distributions were extensive in the digestive system. Strong or general met-Enk immunoreactivity was observed in the inner epithelial cells of the bulbus oris, esophagus, stomach, gastric cecum, intestine, anterior salivary glands and the adventitia of the intestine and rectum, and so was the delta opioid receptor immunoreactivity in the inner epithelial cells of the bulbus oris, esophagus, and crop, however, they were weak in other parts. Combining with delta opioid receptor, met-Enk may be involved in the regulations of food intake, absorption, movement of gastrointestinal smooth muscle and secretion of digestive gland. The different densities of met-Enk and delta opioid receptor may be related to the different functions in the digestive system of O. ocellatus. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Hummingbird - A Very Low Cost, High Delta V Spacecraft for Solar System Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on Microcosm's development of a high delta-V small Earth observation spacecraft called NanoEye, with a planned recurring cost of $2 million, Microcosm will...

  12. A dynamic soil chamber system coupled with a tunable diode laser for online measurements of delta-13C, delta-18O, and efflux rate of soil respired CO2

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Heath H [Los Alamos National Laboratory; Mcdowell, Nate [Los Alamos National Laboratory; Hanson, David [UNM; Hunt, John [LANDCARE RESEARCH

    2009-01-01

    High frequency observations of the stable isotopic composition of CO(2) effluxes from soil have been sparse due in part to measurement challenges. We have developed an open-system method that utilizes a flow-through chamber coupled to a tunable diode laser (TDL) to quantify the rate of soil CO(2) efflux and its delta(13)C and delta(18)O values (delta(13)C(R) and delta(18)O(R), respectively). We tested the method first in the laboratory using an artificial soil test column and then in a semi-arid woodland. We found that the CO(2) efflux rates of 1.2 to 7.3 micromol m(-2) s(-1) measured by the chamber-TDL system were similar to measurements made using the chamber and an infrared gas analyzer (IRGA) (R(2) = 0.99) and compared well with efflux rates generated from the soil test column (R(2) = 0.94). Measured delta(13)C and delta(18)O values of CO(2) efflux using the chamber-TDL system at 2 min intervals were not significantly different from source air values across all efflux rates after accounting for diffusive enrichment. Field measurements during drought demonstrated a strong dependency of CO(2) efflux and isotopic composition on soil water content. Addition of water to the soil beneath the chamber resulted in average changes of +6.9 micromol m(-2) s(-1), -5.0 per thousand, and -55.0 per thousand for soil CO(2) efflux, delta(13)C(R) and delta(18)O(R), respectively. All three variables initiated responses within 2 min of water addition, with peak responses observed within 10 min for isotopes and 20 min for efflux. The observed delta(18)O(R) was more enriched than predicted from temperature-dependent H(2)O-CO(2) equilibration theory, similar to other recent observations of delta(18)O(R) from dry soils (Wingate L, Seibt U, Maseyk K, Ogee J, Almeida P, Yakir D, Pereira JS, Mencuccini M. Global Change Biol. 2008; 14: 2178). The soil chamber coupled with the TDL was found to be an effective method for capturing soil CO(2) efflux and its stable isotope composition at high

  13. Circuits and systems based on delta modulation linear, nonlinear and mixed mode processing

    CERN Document Server

    Zrilic, Djuro G

    2005-01-01

    This book is intended for students and professionals who are interested in the field of digital signal processing of delta-sigma modulated sequences. The overall focus is on the development of algorithms and circuits for linear, non-linear, and mixed mode processing of delta-sigma modulated pulse streams. The material presented here is directly relevant to applications in digital communication, DSP, instrumentation, and control.

  14. Experimental evaluation of a digitized fiber-wireless system employing sigma delta modulation.

    Science.gov (United States)

    Pessoa, Luis M; Coelho, Diogo; Salgado, Henrique M

    2014-07-14

    Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments.

  15. Systems Biology Strategy Reveals PKC-delta is Key for Sensitizing TRAIL-Resistant Human Fibrosarcoma

    Directory of Open Access Journals (Sweden)

    Kentaro eHayashi

    2015-01-01

    Full Text Available Cancer cells are highly variable and resistant to therapeutic intervention. Recently, the use of the tumor necrosis factor related apoptosis-inducing ligand (TRAIL induced treatment is gaining momentum, due to TRAIL’s ability to specifically target cancers with limited effect on normal cells. However, several malignant cancer types still remain non-sensitive to TRAIL. Previously, we developed a dynamic computational model, based on perturbation-response approach, and predicted protein kinase C (PKC as the most effective target, with over 95% capacity to kill human fibrosarcoma (HT1080 in TRAIL stimulation (Piras, V. et al. 2011, Scientific Reports. Here, to validate the model prediction, which has significant implications for cancer treatment, we conducted experiments on two TRAIL-resistant cancer cell lines (HT1080 and HT29. Using PKC inhibitor Bisindolylmaleimide I, we first demonstrate, as predicted by our previous model, cell viability is significantly impaired with over 95% death of both cancer types. Next, to identify crucial PKC isoform from 10 known members, we analyzed their mRNA expressions in HT1080 cells and shortlisted 4 isoforms for siRNA knock-down (KD experiments. From these KDs, PKC-delta produced the most cancer cell death in conjunction with TRAIL. Overall, systems biology approach, combining model prediction with experimental validation, holds promise for TRAIL-based cancer therapy.

  16. Coastal aquifer groundwater dynamics and salt intrusion: Monitoring system of river Neretva delta

    Science.gov (United States)

    Srzić, Veljko; Vranješ, Mijo; Deković, Jure; Romić, Davor; Zovko, Monika; Milin, Marin

    2017-04-01

    River Neretva delta is located in southern part of Croatia and creates a complex surface- groundwater system influenced by tidal forces characteristic for Adriatic Sea and river Neretva whose discharge varies from 70 - 2700 m3/s over the year. From agricultural point of view, area is used widely for fruit production which implies existence and functionality of complex drainage system consisted of a net of lateral channels and pumping station plants with the capacity of app. 25 m3/s. Area of interest covers app 3500 ha and is bounded by river Neretva from North and Adriatic sea from West. Southern and eastern boundaries are dominantly karstic hills. Lover aquifer is confined with app depth of 65 m, made of fine gravel. Aquitard is a 15 m height layer of clay. Upper aquifer in unconfined with depth of app 10-20 m. Inside the area of interest there are 8 wells installed (each aquifer 4) measuring piezometric head on hourly/daily temporal scale. Sea level measurements are also made capturing for long term tidal oscillations. Discharge measurements are made few km downstream from hydropower plant Mostar (Bosnia and Herzegovina), while three meteorological stations for rainfall measurements are located at the area boundaries. Salt water concentration, pH and resistivity values have been measured locally, app 6 times per year for last 10 years. Results imply confined aquifer is dominantly influenced by the sea level while tidal effects are noticed 9 km upstream the river Neretva with delay of 9-12 minutes compared to sea level. Salt water cline inside the river is related to tidal effects and river discharge, with potential presence at distances of more than 15 km upstream from the sea. Salt water intrusion dominantly occurs through confined aquifer while vertical transport of salt is supposed to be enhanced by the effects of drainage system.

  17. Effect of Delta-9-tetrahydrocannabinol on mouse resistance to systemic Candida albicans infection.

    Directory of Open Access Journals (Sweden)

    Gideon W Blumstein

    Full Text Available Delta-9-tetrahydrocannabinol (Δ9-THC, the psychoactive component of marijuana, is known to suppress the immune responses to bacterial, viral and protozoan infections, but its effects on fungal infections have not been studied. Therefore, we investigated the effects of chronic Δ9-THC treatment on mouse resistance to systemic Candida albicans (C. albicans infection. To determine the outcome of chronic Δ9-THC treatment on primary, acute systemic candidiasis, c57BL/6 mice were given vehicle or Δ9-THC (16 mg/kg in vehicle on days 1-4, 8-11 and 15-18. On day 19, mice were infected with 5×10(5 C. albicans. We also determined the effect of chronic Δ9-THC (4-64 mg/kg treatment on mice infected with a non-lethal dose of 7.5×10(4 C. albicans on day 2, followed by a higher challenge with 5×10(5 C. albicans on day 19. Mouse resistance to the infection was assessed by survival and tissue fungal load. Serum cytokine levels were determine to evaluate the immune responses. In the acute infection, chronic Δ9-THC treatment had no effect on mouse survival or tissue fungal load when compared to vehicle treated mice. However, Δ9-THC significantly suppressed IL-12p70 and IL-12p40 as well as marginally suppressed IL-17 versus vehicle treated mice. In comparison, when mice were given a secondary yeast infection, Δ9-THC significantly decreased survival, increased tissue fungal burden and suppressed serum IFN-γ and IL-12p40 levels compared to vehicle treated mice. The data showed that chronic Δ9-THC treatment decreased the efficacy of the memory immune response to candida infection, which correlated with a decrease in IFN-γ that was only observed after the secondary candida challenge.

  18. System Analysis and Implementation of Delta-Sigma Modulator Topologies with Low Gain Amplifiers in 90nm CMOS

    OpenAIRE

    Shahzad, Bilal

    2011-01-01

    Data converters are one of the key components in many applications ranging from wireless communication to data acquisitions system, sensors, audio electronics, video display electronics and analog microcontrollers. All of these use some type of data converter to perform the task of signal processing/condition for example in RF transceivers the received analog signal after passing through filters is converted to digital signal for further processing. The use of delta-sigma modulators nowadays ...

  19. Eolian Dune, interdune, sand sheet, and Siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran Area, Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

    1983-02-01

    An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks, sources, (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

  20. Eolian dune, interdune, sand sheet, and siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran area, Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

    1983-02-01

    An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks (dunes), sources (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

  1. Policy, systems, and environmental change in the Mississippi Delta: considerations for evaluation design.

    Science.gov (United States)

    Kegler, Michelle C; Honeycutt, Sally; Davis, Melvin; Dauria, Emily; Berg, Carla; Dove, Cassandra; Gamble, Abigail; Hawkins, Jackie

    2015-04-01

    Community-level policy, systems, and environmental (PSE) change strategies may offer an economical and sustainable approach to chronic disease prevention. The rapidly growing number of untested but promising PSE strategies currently underway offers an exciting opportunity to establish practice-based evidence for this approach. This article presents lessons learned from an evaluation of a community-based PSE initiative targeting stroke and cardiovascular disease prevention in the Mississippi Delta. Its purpose is to describe one approach to evaluating this type of PSE initiative, to stimulate discussion about best practices for evaluating PSE strategies, and to inform future evaluation and research efforts to expand practice-based evidence. The evaluation used a descriptive mixed-methods design and focused on the second year of a multisectoral, multiyear initiative. Cross-sectional data were collected in the summer and fall of 2010 using four data collection instruments: a grantee interview guide (n = 32), a health council member survey (n = 256), an organizational survey (n = 60), and a grantee progress report (n = 26). Fifty-eight PSE changes were assessed across five sectors: health, faith, education, worksite, and community/city government. PSE strategies aligned with increased access to physical activity opportunities, healthy food and beverage options, quality health care, and reduced exposure to tobacco. Results showed that grantees were successful in completing a series of steps toward PSE change and that sector-specific initiatives resulted in a range of PSE changes that were completed or in progress. Considerations for designing evaluations of community-based PSE initiatives are discussed. © 2015 Society for Public Health Education.

  2. Delta Dynamics

    DEFF Research Database (Denmark)

    Bendixen, Mette

    . The warming air temperature affects the soil temperature and permafrost thaws and destabilizes the material in the coastal zone. In Greenland, the warming temperature lowers the surface mass balance of the Greenland Ice Sheet and more material is transported to the coastal zone. The sea ice extent is thinning...... of a fjord and the second type is a wider fan-shaped open delta. Most deltas are directly coupled to the Greenland Ice Sheet or local icecaps and are highly influenced by the dynamics in the catchments. It is demonstrated how a modern changing climate directly affects delta dynamics, and that Greenlandic...

  3. Hypothetical First Order abs(DELTA S) = 2 Transitions in the K sup 0 - (anti)K sup 0 System

    CERN Document Server

    Piskorski, J

    2003-01-01

    The influence of a hypothetical CP violating abs(DELTA S) = 2 interaction on the masses and lifetimes of neutral mesons K sup 0 and (anti)K sup 0 is investigated. It is shown, that the assumption of the existence of this superweak interaction does not significantly affect these parameters if phenomenological constraints based on recent experiments are imposed. To establish this result we use a computer simulation of a parameter corresponding to the difference between the diagonal elements of the effective Hamiltonian governing the time evolution in the K sup 0 - (anti)K sup 0 system. Instead of the widely used Lee, Oehme and Yang approximation which is insensitive to the abs(DELTA S) = 2 interaction we use a formalism based on the Krolikowski-Rzewuski equation. (author)

  4. Towards a real-time forecasting system for the San Francisco bay/estuary and rive delta

    Science.gov (United States)

    Zhang, H.; Chao, Y.; Farrara, J. D.; Chai, F.; Dugdale, R. C.; Wilkerson, F. P.; Zhang, Y. J.; Ateljevich, E.

    2016-02-01

    An unstructured grid model based on SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) is being developed to address complex resource management questions in the San Francisco Bay/Estuary and Sacramento-San Joaquin River Delta (Bay-Delta). The air-sea fluxes are provided by a high-resolution (3-km) mesoscale atmospheric model (COAMPS). The river discharge data are used as the lateral boundary condition upstream. The coastal ocean boundary condition is derived from a structured grid California coastal ocean model based on ROMS. Results from a 10-year (2004-2015) hindcast will be presented focusing on variability on multiple time scales from tides, weather, annual to interannual. The recent warming during 2014 in response to the Pacific and California coastal warming will be described. Adding a sediment transport model as well as a biogeochemical/ecosystem model will be discussed.

  5. Measurement of C and N isotopes of geological samples using Delta V Plus Stable Isotope Ratio Mass Spectrometer via different preparatory systems

    Digital Repository Service at National Institute of Oceanography (India)

    Karapurkar, S.; Methar, A.; Agnihotri, R.

    standardization of newly acquired IRMS (Delta V Plus; Thermo) dedicated for measurements of C & N isotopes in a variety of geological solid samples. Results were calibrated against each other using different preparatory systems such as on-line combustion...

  6. Competition between uplift and transverse sedimentation in an experimental delta

    Science.gov (United States)

    Grimaud, Jean-Louis; Paola, Chris; Ellis, Chris

    2017-07-01

    Mass is commonly injected into alluvial systems either laterally by transport from source regions or vertically from below via local uplift. We report results on the competition between these two fundamental processes, using an experimental basin with a deformable substrate. The lateral supply is via two alluvial fans on orthogonal walls of the basin; the uplifting region is downstream of one of the fans (axial) and opposite to the other (transverse). We show that the presence of a transverse sediment input increases the erosion rate of the uplifting region by pushing the mixing zone between the two alluvial sources against the uplifting mass. However, increase in sediment delivery to the transverse fan does not cause a proportional increase in erosion rate of the uplifting region. Instead, the system reaches a steady state balance between uplift and erosion induced by the transverse fan, such that there is no change in the total mass above the active alluvial surface—a lateral analog of the classical steady state between vertical erosion and uplift. We also show that the mixing zone is instrumental in limiting upstream aggradation and funneling sediments to the shore, resulting in limited river lateral mobility and increased shoreline progradation. Hence, the interaction between alluvial sources buffers river erosion and leads to consistent deviations from predictions of the area of influence of each fan based on simple mass-balance arguments. In the Ganges-Brahmaputra-Meghna delta, we suggest that similar dynamics help stabilize the Brahmaputra River course in the Jamuna Valley during Holocene time.

  7. Quantitative Prograde P-T Paths From Inclusion Assemblages in Eclogitic Garnets

    Science.gov (United States)

    Essene, E. J.; Page, F. Z.; Mukasa, S. B.

    2003-12-01

    Many workers have used garnet inclusions as qualitative indicators of the early history of tectonically exposed eclogites. Assemblages indicative of crustal facies combined with standard P-T conditions of those facies and thermobarometry on the matrix eclogite constrain the prograde path. However, now that conditions of some blueschist, amphibolite and granulite facies rocks have been extended to much higher pressures, in the range of 10-20 kbar, those assignments are in need of review. While undertaking studies on eclogites from the Blue Ridge of North Carolina and the Franciscan in northern California, the authors have identified key inclusion assemblages of sphene-rutile-epidote-quartz and phengite-omphacite together with garnet that constrain the prograde P-T path based on univariant assemblages corrected for observed solid solutions. Equilibria that have proved most useful are those bounding epidote stability and two key reactions, one involving sphene/rutile: (1) clinozoisite + sphene = grossular + rutile + H2O, and the second being the phengite barometer: garnet + Mg-celadonite = clinopyroxene + muscovite. Reactions (1) and (2) have negative slopes, intersecting with the Mg/Fe KD garnet-clinopyroxene thermometer and providing a reasonable estimate of pre- to syn-eclogite facies P-T. In the case of the Bakersville eclogite samples from North Carolina, the inclusion assemblage yields 10 +/- 2 kbar and 500 +/- 50° C with reaction (1) compared to the peak assemblage at P > 15 +/- 2 kbar and 700 +/- 50° C. These data combined with evidence for a granulite facies overprint indicate a clockwise P-T path for those eclogites. A similar study on the Healdsburg eclogite samples from California yields about 500° C and 12 +/- 1 kbar for the garnet cores, 14 +/- 2 kbar for mantles and 16 +/- 2 kbar for rim-matrix assemblages. The introduction of late glaucophane, epidote and chlorite partially replacing omphacite and garnet implies a retrograde return to the blueschist

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

    Science.gov (United States)

    Foufoula-Georgiou, E.

    2013-12-01

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

  9. Phenological cues intrinsic in indigenous knowledge systems for forecasting seasonal climate in the Delta State of Nigeria

    Science.gov (United States)

    Fitchett, Jennifer M.; Ebhuoma, Eromose

    2017-12-01

    Shifts in the timing of phenological events in plants and animals are cited as one of the most robust bioindicators of climate change. Much effort has thus been placed on the collection of phenological datasets, the quantification of the rates of phenological shifts and the association of these shifts with recorded meteorological data. These outputs are of value both in tracking the severity of climate change and in facilitating more robust management approaches in forestry and agriculture to changing climatic conditions. However, such an approach requires meteorological and phenological records spanning multiple decades. For communities in the Delta State of Nigeria, small-scale farming communities do not have access to meteorological records, and the dissemination of government issued daily to seasonal forecasts has only taken place in recent years. Their ability to survive inter-annual to inter-decadal climatic variability and longer-term climatic change has thus relied on well-entrenched indigenous knowledge systems (IKS). An analysis of the environmental cues that are used to infer the timing and amount of rainfall by farmers from three communities in the Delta State reveals a reliance on phenological events, including the croaking of frogs, the appearance of red millipedes and the emergence of fresh rubber tree and cassava leaves. These represent the first recorded awareness of phenology within the Delta State of Nigeria, and a potentially valuable source of phenological data. However, the reliance of these indicators is of concern given the rapid phenological shifts occurring in response to climate change.

  10. Digital shoreline analysis system-based change detection along the highly eroding Krishna-Godavari delta front

    Science.gov (United States)

    Kallepalli, Akhil; Kakani, Nageswara Rao; James, David B.; Richardson, Mark A.

    2017-07-01

    Coastal regions are highly vulnerable to rising sea levels due to global warming. Previous Intergovernmental Panel on Climate Change (2013) predictions of 26 to 82 cm global sea level rise are now considered conservative. Subsequent investigations predict much higher levels which would displace 10% of the world's population living less than 10 m above sea level. Remote sensing and GIS technologies form the mainstay of models on coastal retreat and inundation to future sea-level rise. This study estimates the varying trends along the Krishna-Godavari (K-G) delta region. The rate of shoreline shift along the 330-km long K-G delta coast was estimated using satellite images between 1977 and 2008. With reference to a selected baseline from along an inland position, end point rate and net shoreline movement were calculated using a GIS-based digital shoreline analysis system. The results indicated a net loss of about 42.1 km2 area during this 31-year period, which is in agreement with previous literature. Considering the nature of landforms and EPR, the future hazard line (or coastline) is predicted for the area; the predication indicates a net erosion of about 57.6 km2 along the K-G delta coast by 2050 AD.

  11. Pliocene-Pleistocene climate change, sea level and uplift history recorded by the Horingbaai fan-delta, NW Namibia

    Science.gov (United States)

    Stollhofen, Harald; Stanistreet, Ian G.; von Hagke, Christoph; Nguno, Anna

    2014-07-01

    Its location on a tectonically relatively stable passive margin and its degree of interaction with the sea make the Horingbaai fan-delta, NW Namibia, an exceptional record of coastal activity, providing insights into the response of ephemeral fluvial systems to changes in climate, sea level and continent-scale uplift. The fan comprises upper, middle and lower segments. The upper fan and middle fan are dominated by a braided river system; only in the upper fan are fluvial sediments interleaved with hyperconcentrated flow deposits. Plio-Pleistocene sea level highstands have left marine terraces on the fan surface which enable correlation with the offshore marine record and provide timelines to constrain fan growth. The bulk of fan-delta progradation took place at ∼ 2.7-2.4 Ma, between the formation of a widespread erosional surface incising the middle Pliocene Karpfenkliff and Kamberg Formations, but prior to the emplacement of the warm-water fauna-bearing late Pliocene "Oyster Terrace" (∼ 2.4-2.2 Ma), an equivalent of the + 30 mP (marine terrace package) in coastal southwestern Africa. Major fan progradation is contemporaneous with widespread regional uplift (~ 12 ± 5 m/Ma) and climate change in southwestern Africa, the latter associated with intensification of northern hemisphere glaciations. Younger fan growth phases are weaker and constrained by < 10 m asl marine terrace bodies that yield mostly cold-water fauna, corresponding to the onset of strong glacial/interglacial climatic fluctuations superimposed on a general aridification trend and the introduction of colder sea-surface temperatures after 2.2 Ma.

  12. The development of the Ganges-Brahmaputra tidal delta plain: construction to maintenance phase changes in platform and channel morphology

    Science.gov (United States)

    Wilson, C.; Goodbred, S. L., Jr.; Hale, R. P.; Bain, R. L.

    2016-12-01

    The lower Ganges-Brahmaputra (G-B) delta can be divided into the fluvial-tidal river mouth and distributaries under active construction by the G-B rivers, and the distal tidally maintained deltaplain. In the active river-mouth, distributaries have constructed 5,000 km2 of large, coalescing islands that define the prograding coastline and subaerial-delta front. Although seasonal riverbank erosion is common, the area as a whole has gained land, primarily via horizontal and vertical accretion of intertidal mudflats and seaward progradation of emergent, tidally-elongated sandy channel-mouth bars. An analysis of historical imagery within the active river mouth shows larger and higher order channels form as merging bars and shoal-islands constrict distributary channels, while lower order creeks emerge secondarily, presumably as flow on shoaling intertidal mudflats becomes channelized and mangrove vegetation takes hold. With waning fluvial input (occurring from major distributary migration or avulsion), tidal and marine processes exhibit a stronger control on sediment transport and distribution, as is happening in the downdrift areas of the G-B tidal delta plain. The relatively pristine Sundarbans mangrove forest covers 4,100 km2 along the coast, while 11,200 km2 of the lower tidal delta plain is densely inhabited (population density up to 1,000/km2) and embanked for agricultural purposes. Although considered moribund or abandoned from direct fluvial sediment input, distal portions of the tidal delta are connected to the sediment transport system by its dense network of tidal channels. The subaerial landscape that was initially constructed by the point-sourced input of coarser-grained fluvial sediment from the mainstem rivers is thereafter maintained predominantly by onshore tidal sediment transport of finer-grained silt, and we observe accretion rates as high as 2-4 cm/y supported on the mangrove platform during the monsoon season. The tidal channels show evidence of

  13. Modelling sand and gravel resources in a Late-Glacial delta system, Lough Neagh, Northern Ireland

    Science.gov (United States)

    Roberson, Sam; Cooper, Rhys; Scanlon, Meredith; Mellett, Claire

    2017-04-01

    Sediment from glacial outwash deposited across central Ulster during deglaciation represent a major resource for aggregate and construction industries in Northern Ireland. Lough Neagh, the largest water body in the UK, acted as an accumulation basin for sediment transported by meltwater during the Late Glacial. Very little is known about the volume or type of aggregate within the Lough, despite over a half a century of sand and gravel extraction. This study presents the results of a resource survey carried out across a 47 km2 area in the northwestern part of the Lough. Multi beam echo sounding and seismic data were collected to constrain sub-bottom stratigraphy within the Lough. Bulk sediment samples from shallow boreholes and surface grabs were analysed for density and particle size to determine the type of sediment present. Volumetric data were combined with borehole logs to build a stratigraphic model of the NW corner of the Lough: lacustrine alluvium overlying a glaciolacustrine delta, underlain by glacial till. This study applies principal component analysis to log-ratio transformed particle-size distributions sampled from within the delta. Principal component scores (PCs) were interpolated within a voxel grid using ordinary kriging to derive complete particle-size distributions throughout the delta deposit. These were combined with measurements of dry density to calculate bulk sediment tonnage for British Standard cement gradings (BS 800 and BS 1200). Uncertainty in sediment tonnage (±1 sigma) was calculated by propagating kriged error variance through principal component score and log-ratio inversion.

  14. Late Holocene evolution of a coupled, mud-dominated delta plain–chenier plain system, coastal Louisiana, USA

    Directory of Open Access Journals (Sweden)

    M. P. Hijma

    2017-11-01

    Full Text Available Major deltas and their adjacent coastal plains are commonly linked by means of coast-parallel fluxes of water, sediment, and nutrients. Observations of the evolution of these interlinked systems over centennial to millennial timescales are essential to understand the interaction between point sources of sediment discharge (i.e. deltaic distributaries and adjacent coastal plains across large spatial (i.e. hundreds of kilometres scales. This information is needed to constrain future generations of numerical models to predict coastal evolution in relation to climate change and other human activities. Here we examine the coastal plain (Chenier Plain, CP adjacent to the Mississippi River delta, one of the world's largest deltas. We use a refined chronology based on 22 new optically stimulated luminescence and 22 new radiocarbon ages to test the hypothesis that cyclic Mississippi subdelta shifting has influenced the evolution of the adjacent CP. We show that over the past 3 kyr, accumulation rates in the CP were generally 0–1 Mt yr−1. However, between 1.2 and 0.5 ka, when the Mississippi River shifted to a position more proximal to the CP, these rates increased to 2.9 ±1.1 Mt yr−1 or 0.5–1.5 % of the total sediment load of the Mississippi River. We conclude that CP evolution during the past 3 kyr was partly a direct consequence of shifting subdeltas, in addition to changing regional sediment sources and modest rates of relative sea-level (RSL rise. The RSL history of the CP during this time period was constrained by new limiting data points from the base of overwash deposits associated with the cheniers. These findings have implications for Mississippi River sediment diversions that are currently being planned to restore portions of this vulnerable coast. Only if such diversions are located in the western portion of the Mississippi Delta plain could they potentially contribute to sustaining the CP shoreline. Our findings

  15. Late Holocene evolution of a coupled, mud-dominated delta plain-chenier plain system, coastal Louisiana, USA

    Science.gov (United States)

    Hijma, Marc P.; Shen, Zhixiong; Törnqvist, Torbjörn E.; Mauz, Barbara

    2017-11-01

    Major deltas and their adjacent coastal plains are commonly linked by means of coast-parallel fluxes of water, sediment, and nutrients. Observations of the evolution of these interlinked systems over centennial to millennial timescales are essential to understand the interaction between point sources of sediment discharge (i.e. deltaic distributaries) and adjacent coastal plains across large spatial (i.e. hundreds of kilometres) scales. This information is needed to constrain future generations of numerical models to predict coastal evolution in relation to climate change and other human activities. Here we examine the coastal plain (Chenier Plain, CP) adjacent to the Mississippi River delta, one of the world's largest deltas. We use a refined chronology based on 22 new optically stimulated luminescence and 22 new radiocarbon ages to test the hypothesis that cyclic Mississippi subdelta shifting has influenced the evolution of the adjacent CP. We show that over the past 3 kyr, accumulation rates in the CP were generally 0-1 Mt yr-1. However, between 1.2 and 0.5 ka, when the Mississippi River shifted to a position more proximal to the CP, these rates increased to 2.9 ±1.1 Mt yr-1 or 0.5-1.5 % of the total sediment load of the Mississippi River. We conclude that CP evolution during the past 3 kyr was partly a direct consequence of shifting subdeltas, in addition to changing regional sediment sources and modest rates of relative sea-level (RSL) rise. The RSL history of the CP during this time period was constrained by new limiting data points from the base of overwash deposits associated with the cheniers. These findings have implications for Mississippi River sediment diversions that are currently being planned to restore portions of this vulnerable coast. Only if such diversions are located in the western portion of the Mississippi Delta plain could they potentially contribute to sustaining the CP shoreline. Our findings highlight the importance of a better

  16. Tiber delta CO2-CH4 degassing: A possible hybrid, tectonically active Sediment-Hosted Geothermal System near Rome

    Science.gov (United States)

    Ciotoli, G.; Etiope, G.; Marra, F.; Florindo, F.; Giraudi, C.; Ruggiero, L.

    2016-01-01

    Fiumicino town in the Tiber River delta, near Rome International Airport (Italy), is historically affected by large amounts of carbon dioxide (CO2) in the ground and gas eruptions triggered by shallow drilling. While it is known that CO2 originates from carbonate thermometamorphism and/or mantle degassing, the origin of methane (CH4) associated with CO2 is uncertain and the outgassing spatial distribution is unknown. Combining isotope gas geochemistry, soil gas, and structural-stratigraphic analyses, we provide evidence for a hybrid fluid source system, classifiable as Sediment-Hosted Geothermal System (SHGS), where biotic CH4 from sedimentary rocks is carried by deep geothermic CO2 through active segments of a half-graben. Molecular and isotopic composition of CH4 and concentration of heavier alkanes (ethane and propane), obtained from gas vents and soil gas throughout the delta area, reveal that thermogenic CH4 (up to 3.7 vol% in soil gas; δ13CCH4: -37 to -40‰ VPDB-Vienna Peedee Belemnite, and δ2HCH4: -162 to -203‰ VSMOW - Vienna Standard Mean Ocean Water in gas vents) prevails over possible microbial and abiotic components. The hydrocarbons likely result from known Meso-Cenozoic petroleum systems of the Latium Tyrrhenian coast. Overmaturation of source rocks or molecular fractionation induced by gas migration are likely responsible for increased C1/C2+ ratios. CO2 and CH4 soil gas anomalies are scattered along NW-SE and W-E alignments, which, based on borehole, geomorphologic, and structural-stratigraphic analyses, coincide with active faults of a half-graben that seems to have controlled the recent evolution of the Tiber delta. This SHGS can be a source of considerable greenhouse gas emissions to the atmosphere and hazards for humans and buildings.

  17. Origin of the Turkwel delta trajectory (Lake Turkana, Kenya): insights from numerical modeling (DIONISOS)

    Science.gov (United States)

    Alexis, Nutz; Pierre, Dietrich; Vafe, Soumahoro; Mathieu, Schuster; Jean-François, Ghienne

    2016-04-01

    Deltas simultaneously respond to modifications in parameters such as water discharge, sediment supply and base-level change. Those parameters are driven by a number of potential external forcing processes, nevertheless mainly corresponding to tectonism and climate. In this study, geomorphology and numerical modeling are coupled in order to provide analysis of the delta complex of the Turkwel River (Lake Turkana, Kenya). The Turkwel delta complex is 35 km long, forming one of the major deltaic systems that has fringed Lake Turkana during the Holocene. It developed during the lake level regression at the end of the holocene African Humid Period and correspond to a typical forced-regressive delta. Trajectory analysis was performed on three transects cross-cutting the deltaic complex. Transects consistently display five slightly descending (slope gradient: >0° to 0.4°) plateaus separated by four abrupt steps of higher slope gradients (1° to 3.8°). Conventional interpretations presume that the deltaic trajectory results from either (1) four abrupt accelerations in lake level fall during the continuous regression, (2) four abrupt declines in sediment supply and/or water discharge during a steady lake level fall or (3) a combination of both. We used numerical stratigraphic modeling (Dionisos) in order to test the aforementioned hypotheses as the origin of observed trajectories. We concluded that causal relationships between sediment supply, lake level change and progradation trajectory are not as straightforward as recurrently envisioned. We think that this contribution brings new lights on the relationships between deltaic architectures and controlling factors.

  18. Discrimination rice cropping systems using multi-temporal Proba-V data in the Mekong Delta, Vietnam

    Science.gov (United States)

    Son, Nguyen-Thanh; Chen, Chi-Farn; Chen, Cheng-Ru; Chang, Ly-Yu; Chiang, Shou-Hao; Lau, Khin-Va

    2016-04-01

    Rice is considered a main source of livelihoods for several billions of people worldwide and plays an important role in the economy of many Asian countries. More than just a food source, rice production is regarded as one of the most important components to maintaining political stability and is also a national subject of economic policy due to domestic food consumption and grain exports. Vietnam is globally one of the largest rice producers and suppliers with more than 80% of the exported rice amount produced from the Mekong River Delta. This delta is one of the three deltas in the world most vulnerable to the climate change, causing the potential loss of rice yields. Thus, spatiotemporal information of rice cropping systems is important for agricultural management to ensure food security and rice grain exports. Coarse resolution satellite data such as MODIS demonstrates the applicability for rice mapping at a large scale. However, the use of MODIS data for such a monitoring purpose still reveals a challenging task due to mixed-pixel issues. The Proba-V satellite launched on 7 May 2013 is a potential candidate for this monitoring purpose because the data include four spectral bands (blue, red, near-infrared and mid-infrared) with a swath of 2,285 km with a spatial resolution of 100 m and temporal resolution of 5 days. This study aimed to investigate the applicability of multi-temporal Proba-V data for mapping rice cropping systems in Mekong Delta River, South Vietnam. The data were processed for 2014-2015 rice cropping seasons, following three main steps: (1) construction of smooth time-series NDVI data, (2) classification of rice cropping systems using crop phenological metrics, and (3) accuracy assessment of the mapping results. The results indicated that the smooth time-series NDVI profiles characterized the temporal spectral responses of rice fields through different growing stages of rice plant, which was critically important for understanding rice crop

  19. Three dimensional facies architecture of ancient delta-front reservoir analogs using ground-penetrating radar with outcrop and core sedimentology with case studies from the Turonian Wall Creek member, Frontier Formation, Wyoming

    Science.gov (United States)

    Lee, Keumsuk

    Ground Penetrating Radar (GPR) measurements are integrated with sedimentology and Global Positioning System data for two delta-front reservoir analogs (the Murphy Creek and Raptor Ridge sites) in the Wall Creek Member of the Frontier Formation in Wyoming. The Murphy Creek site is imaged to detail the geometry of a river-dominated delta front, and to estimate the volume of its bar deposits. The Raptor Ridge site delineates the 3D internal structure of a mixed-influenced delta front, to predict the distribution of low permeability concretions throughout a 3D GPR volume, and to provide a km-scale depositional model. The Murphy Creek and Raptor Ridge sites both contain stacked mouth-bar deposits characterized by sharp-based, top-truncated, seaward-dipping foreset beds between a prodelta mud layer and an erosional top boundary. Sedimentologically controlled GPR interpretations are, in general, consistent with the outcrops, including the paleotransport measurements. The Murphy Creek site consists of sedimentary-gravity-flow induced compound mouth bars varying with sedimentation rates, and their estimated volumes suggest that bars may accrete landward as well as basinward. The Raptor Ridge site shows three main radar facies, corresponding to seaward-prograding mouth bars, tide-influenced mouth bars, and channels. The prograding mouth bar is a dominant facies architectural element at the Raptor Ridge. Nine 3D facies bodies were identified within the 3D GPR volume. The predicted calcite cements are distributed in a dendritic, aggregate fashion. Interpretation of the 2D GPR data grids at Raptor Ridge shows nine and eight 3D facies bodies, respectively. The dominant facies architectural element falls into two (distal and proximal) delta-front mouth bars, separated by a local erosional boundary, and cut by shallow delta-slope channels. A two-phase depositional model suggests the development of an Upper Cretaceous, mixed-influenced delta, forming two separate delta lobes before

  20. Systems Dynamics Modelling Identifies (Un)Sustainable Rice Cultivation Strategies for the Mekong Delta Under Upstream Hydropower Development

    Science.gov (United States)

    Darby, S. E.; Chapman, A.; Hackney, C. R.; Leyland, J.; Parsons, D. R.; Aalto, R. E.; Nicholas, A. P.; Best, J.

    2016-12-01

    The Vietnamese Mekong delta is one of the world's largest rice producing regions, but it is facing a major sustainability challenge. The delta is being `drowned' by rising relative sea-levels, a situation that is being exacerbated by a reduction in the supply of rivers sediments due to a combination of climate change and sediment trapping linked to the construction of large hydropower dams in upstream countries. Poverty is prevalent and farmers face many challenges, such as declining productivity, income insecurity and debt; they are therefore reliant on natural ecosystem services, notably soil nutrient replenishment by sediment deposition during floods, to minimise dependence on chemical fertilisers. Meanwhile, the drive to intensify rice production (a key national policy goal that has underpinned the region's recent economic development) has been achieved by replacing the traditional use of `low' (0-2m in height) dyke networks with `high' (>3.5m) dyke networks. Since rice production takes place within these dyke rings, this has enabled a switch from traditional cultivation techniques (double cropping within low dyke rings) to a new system of triple cropping (in which an extra crop can be grown due to the exclusion of flood waters during the monsoon season) within the high dykes. This involves trading off immediate benefits (protection against floods; improved rice production) against long term disadvantages (the exclusion of sediment accelerates relative sea-level rise, adding to flood risk in the long term, while sediment borne nutrients are key to agricultural productivity in the long term). Here we use systems dynamics modelling to demonstrate that current rice cultivation strategies are a maladaptation which, under a future of declining sediment loads due to upstream hydropower development, are not sustainable in the long term and present recommendations for more sustainable water management policies in the delta's rice growing region.

  1. Changing Course - The Moffatt & Nichol Team Solution- A "Systems Approach" to a consolidated and sustainable Lower Mississippi River Delta.

    Science.gov (United States)

    Hird, J. P.; Twilley, R.; Shelden, J.; Carney, J.; Georgiou, I. Y.; Agre, C.

    2016-02-01

    In response to the Changing Course Design Competition a bold, innovative "systems approach" to link the specific needs of the region's ecosystem, economy and community is proposed. "The Giving Delta" plan empowers the Mississippi River's seasonal natural flood pulse to maximized sediment capture in order to build and maintain wetlands, mitigate the effects of climate change and subsidence, and to slow the inevitable marine transgression of the Delta. Sediment capture is optimized by a series of sediment retention strategies and passive sediment diversion structures, as well as establishing a new deep draft navigation channel connected to the Barataria Bay shoreline littoral zone 40 miles north of the current channel.This paradigm shift from "flood control" to "controlled floods", connects the River's natural flood pulse to the coastal landscape. Using hydraulic residence time in the basin as a design and operational criteria for these controlled and passive structures, balances estuarine recovery and system response tolerance in order to determine the magnitude of the peak flows possible without intolerable salinity suppression in the receiving basins. Seasonal salinity gradients can be established that enable the diversion program to operate in harmony with and promote regional fisheries. On an annual basis, fisheries, communities and ecosystems will adapt to seasonally changing conditions. This plan is not designed to completely rebuild the wetlands that have been lost over the last century. Instead, the design encourages wetland adaptation to accelerated sea level rise in the coastal basins. With this plan, the basin ecologies would "self-organize" in parallel to the human settlement's natural ability to adapt and change to this long-term vision, as a new, consolidated and sustainable Delta emerges. By establishing a framework of implementation over 100 years, incremental adaptation minimizes individual uncertainty and costs within each human generation.

  2. Effect of environmental change on the morphology of tidally influenced deltas over multi-decadal timescale

    Science.gov (United States)

    Angamuthu, Balaji; Darby, Stephen; Nicholls, Robert

    2017-04-01

    An understanding of the geomorphological processes affecting deltas is essential to improve our understanding of the risks that deltas face, especially as human impacts are likely to intensify in the future. Unfortunately, there is limited reliable data on river deltas, meaning that the task of demonstrating the links between morphodynamic and environmental change is challenging. This presentation aims to answer the questions of how delta morphology evolves over multi-decadal timescales under multiple drivers, focussing on tidally-influenced deltas, as some of these, such as the Ganges-Brahmaputra-Meghna (GBM) delta are heavily populated. A series of idealised model simulations over 102 years were used to explore the influence of three key drivers on delta morphodynamics, both individually and together: (i) varying combinations of water and sediment discharges from the upstream catchment, (ii) varying rates of relative sea-level rise (RSLR), and (iii) selected human interventions within the delta, such as polders, cross-dams and changing land cover. Model simulations revealed that delta progradation rates are more sensitive to variations in water discharge than variations in fluvial sediment supply. Unlike mere aggradation during RSLR, the delta front experienced aggradational progradation due to tides. As expected, the area of the simulated sub-aerial delta increases with increasing sediment discharge, but decreases with increasing water discharge. But, human modifications are important. For example, the sub-aerial delta shrinks with increasing RSLR, but it does not when the sub-aerial delta is polderised, provided the polders are restricted from erosion. However, the polders are vulnerable to flooding as they lose relative elevation and can make the delta building process unsustainable. Cross-dams built to steer zones of land accretion within the delta accomplish their local goal, but may not result in net land gain at the scale of the delta. Applying these

  3. Superconductivity in 2-2-3 system Y2Ba2Cu2O(8+delta)

    Science.gov (United States)

    Joshi, H. H.; Baldha, G. J.; Jotania, R. B.; Joshi, S. M.; Mohan, H.; Pandya, P. B.; Pandya, H. N.; Kulkarni, R. G.

    1991-01-01

    Researchers synthesized a new high T(sub c) 2-2-3 superconductor Y2Ba2Cu3O(8+delta) by a special preparation technique and characterized it by ac-susceptibility measurements. Diamagnetism and Meissner effect sets in at low fields and superconducting transition onsets at 90 K. The systematic investigation of the real and imaginary components of ac-susceptibility as a function of temperature and applied ac magnetic field reveals that the magnetic behavior is that of a granular type superconductor.

  4. EVIDENCE FOR LADINIAN (MIDDLE TRIASSIC PLATFORM PROGRADATION IN THE GYULAKESZI AREA, TAPOLCA BASIN, WESTERN HUNGARY: MICROFACIES ANALYSIS AND BIOSTRATIGRAPHY

    Directory of Open Access Journals (Sweden)

    ZSOLT RÓBERT NAGY

    2014-07-01

    Full Text Available A shallowing-upward carbonate sequence was studied from the outcrop at Gyulakeszi, Tapolca Basin (western Hungary, and it is interpreted as a Middle Triassic (Curionii or younger platform progradation. Two lithostratigraphic units are distinguished. Microfacies analysis and micropaleontological investigation conducted on the red nodular, cherty limestone (Vászoly and Buchenstein formations suggest that the lower unit was deposited during the Reitzi and the Secedensis ammonoid zones. The overlying white platform limestone (upper unit is typical of a prograding platform and includes gravity-driven deposits at the base followed by periplatform facies deposited in shallow marine warm waters around the fair-weather wave base. The section at Gyulakeszi was unaffected by fabric-destructive dolomitization, which is uncharacteristic of similar platform facies in the Balaton Highland. Isopachous and radiaxial fibrous calcite cement found in the grainstone and boundstone facies are indicative of early lithification and diagenesis in the marine phreatic zone. “Evinospongiae”-type cement is described for the first time from the Balaton Highland and it is similar to the outer platform cements published previously from the Alps (Italy and Austria. The progradation could have advanced over the pelagic limestones as early as the Curionii zone, which is an undocumented event in the Veszprém Plateau. Similar event, however, is well known from the Western Dolomites, where aggradation was followed by intense progradation during the Gredleri and Archelaus ammonoid zones. The length of this progradation event at Gyulakeszi, however, is ambiguous since proven Ladinian (Longobardian rocks are not exposed in the study area and were not penetrated by boreholes in the Tapolca Basin.

  5. Time to death analysis of road traffic accidents in relation to delta V, drunk driving, and restraint systems.

    Science.gov (United States)

    Ju, Yonghan; Sohn, So Young

    2014-01-01

    The main goal of this research is to identify variables related to the expected time to death due to road traffic accidents (RTAs). Such research is expected to be useful in improving safety laws and regulations and developing new safety systems. The resulting information is crucial not only for reducing accident fatalities but for assessing related insurance policies. In this article, we analyze factors that are potentially associated with variation in the expected survival time after a road traffic accident using Weibull regression. In particular, we consider the association with alcohol involvement, delta V, and restraint systems. Our empirical results, obtained based on the NASS-CDS, indicate that the expected survival time for non-alcohol-impaired drivers is 3.23 times longer at a delta V of 50 km/h than that for alcohol-impaired drivers under the same conditions. In addition, it was observed that, even when occupants were alcohol-impaired, if they were protected by both air bags and seat belts, their expected survival time after an RTA increased 2.59-fold compared to alcohol-impaired drivers who used only seat belts. Our findings may be useful in improving road traffic safety and insurance policies by offering insights into the factors that reduce fatalities.

  6. Secular resonances between bodies on close orbits II: prograde and retrograde orbits for irregular satellites

    Science.gov (United States)

    Li, Daohai; Christou, Apostolos A.

    2017-09-01

    In extending the analysis of the four secular resonances between close orbits in Li and Christou (Celest Mech Dyn Astron 125:133-160, 2016) (Paper I), we generalise the semianalytical model so that it applies to both prograde and retrograde orbits with a one-to-one map between the resonances in the two regimes. We propose the general form of the critical angle to be a linear combination of apsidal and nodal differences between the two orbits b_1 Δ π + b_2 Δ Ω, forming a collection of secular resonances in which the ones studied in Paper I are among the strongest. Test of the model in the orbital vicinity of massive satellites with physical and orbital parameters similar to those of the irregular satellites Himalia at Jupiter and Phoebe at Saturn shows that {>}20 and {>}40% of phase space is affected by these resonances, respectively. The survivability of the resonances is confirmed using numerical integration of the full Newtonian equations of motion. We observe that the lowest order resonances with b_1+|b_2|≤ 3 persist, while even higher-order resonances, up to b_1+|b_2|≥ 7, survive. Depending on the mass, between 10 and 60% of the integrated test particles are captured in these secular resonances, in agreement with the phase space analysis in the semianalytical model.

  7. Subduction-related prograde metamorphism of the ultramafic members of the Central-Sudetic Ophiolite (SW Poland)

    Science.gov (United States)

    Wojtulek, Piotr; Puziewicz, Jacek; Ntaflos, Theodoros

    2016-04-01

    ~680-780°C. The BBM serpentinites have mineral assemblage (antigorite-olivine-diopside-tremolite) typical for ~420-490°C and the ŚM rocks containing antigorite-olivine-diopside were altered at ~380-460°C (cf. phase diagram based on Berman et al., 1986). Similar mineral succession indicative for prograde metamorphism of serpentinites is typical for alteration in subduction zone setting and occurs in serpentinites from the Lanzo Massif in Alps (Debret et al., 2013) and in the mantle wedge serpentinites from Guatemala (Kodolanyi et al., 2012). This abstract was prepared as a part of the project of the National Science Centre of Poland ("Evolution of serpentinic members of the Lower Silesia ophiolites", DEC-2012/07/N/ST10/03934). References Berman, R. G., Engi, M., Greenwood, H. J., Brown, T. H., 1986. Derivation of internally-consistent thermodynamic data by the technique of mathematical programming: a review with application to the system MgO-SiO2-H2O. Journal of Petrology 27, 1331-1364. Debret, B., Nicollet, C., Schwartz, S., Andreani, M., Godard, M., 2013. Three steps of serpentinization in an eclogitized oceanic serpentinization front (Lanzo Massif - Western Alps). Journal of Metamorphic Geology 31, 65 - 186. Kodolányi, J., Pettke, T., Spandler, C., Kamber, B.S. and Gméling, K., 2012. Geochemistry of ocean floor and forearc serpentinites: Constraints on the ultramafic input to subduction zones. Journal of Petrology 53, 235-270.

  8. A brief history and summary of the effects of river engineering and dams on the Mississippi River system and delta

    Science.gov (United States)

    Alexander, Jason S.; Wilson, Richard C.; Green, W. Reed

    2012-01-01

    The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike

  9. Shoreline response to environmental forcings: A case study in the Wax Lake Delta, Gulf of Mexico

    Science.gov (United States)

    Geleynse, Nathanael; Hiatt, Matt; Sangireddy, Harish; Passalacqua, Paola; Mohrig, David

    2013-04-01

    River deltas are well-known landforms within both hydrology and geology. However, both their hydrodynamics and morphodynamics are not well understood, in part because of scarcity of historical data that document the growth or retreat of their channel networks, islands and associated shorelines. Here, we present an analysis of Landsat imagery of the Wax Lake Delta, a young and relatively rapidly prograding delta in the shallow Atchafalaya Basin, Gulf of Mexico. Taking advantage of a recently developed semi-automatic shoreline extraction method [Geleynse et al, 2012], we show how suitably-defined shorelines can be retrieved from satellite imagery. The effect of tides, river floods, storm surges, and vegetation cover on the extracted shoreline of Wax Lake Delta can be quantified as well as the physical relationship between the boundary of the subareal and subaqueous portions of the delta (hydrodynamic shoreline) and the morphodynamic shoreline.

  10. Connectivity of Multi-Channel Fluvial Systems: A Comparison of Topology Metrics for Braided Rivers and Delta Networks

    Science.gov (United States)

    Tejedor, A.; Marra, W. A.; Addink, E. A.; Foufoula-Georgiou, E.; Kleinhans, M. G.

    2016-12-01

    Advancing quantitative understanding of the structure and dynamics of complex networks has transformed research in many fields as diverse as protein interactions in a cell to page connectivity in the World Wide Web and relationships in human societies. However, Geosciences have not benefited much from this new conceptual framework, although connectivity is at the center of many processes in hydro-geomorphology. One of the first efforts in this direction was the seminal work of Smart and Moruzzi (1971), proposing the use of graph theory for studying the intricate structure of delta channel networks. In recent years, this preliminary work has precipitated in a body of research that examines the connectivity of multiple-channel fluvial systems, such as delta networks and braided rivers. In this work, we compare two approaches recently introduced in the literature: (1) Marra et al. (2014) utilized network centrality measures to identify important channels in a braided section of the Jamuna River, and used the changes of bifurcations within the network over time to explain the overall river evolution; and (2) Tejedor et al. (2015a,b) developed a set of metrics to characterize the complexity of deltaic channel networks, as well as defined a vulnerability index that quantifies the relative change of sediment and water delivery to the shoreline outlets in response to upstream perturbations. Here we present a comparative analysis of metrics of centrality and vulnerability applied to both braided and deltaic channel networks to depict critical channels in those systems, i.e., channels where a change would contribute more substantially to overall system changes, and to understand what attributes of interest in a channel network are most succinctly depicted in what metrics. Marra, W. A., Kleinhans, M. G., & Addink, E. A. (2014). Earth Surface Processes and Landforms, doi:10.1002/esp.3482Smart, J. S., and V. L. Moruzzi (1971), Quantitative properties of delta channel networks

  11. Tidal modulated flow and sediment flux through Wax Lake Delta distributary channels: Implications for delta development

    Directory of Open Access Journals (Sweden)

    K. Hanegan

    2015-03-01

    Full Text Available In this study, a Delft3D model of the Wax Lake Delta was developed to simulate flow and sediment flux through delta distributary channels. The model was calibrated for tidal constituents as well as velocity and sediment concentration across channel transects. The calibrated model was then used to simulate full spring–neap tidal cycles under constant low flow upstream boundary conditions, with grain size variation in suspended load represented using two sediment fractions. Flow and sediment flux results through distributary channel cross-sections were examined for spatial and temporal variability with the goal of characterizing the role of tides in sediment reworking and delta development. The Wax Lake Delta has prograded through channel extension, river mouth bar deposition, and channel bifurcation. Here we show that tidal modulation of currents influences suspended sand transport, and spatial acceleration through distributary channels at low tides is sufficient to suspend sand in distal reaches during lower flows. The basinward-increasing transport capacity in distributary channels indicates that erosive channel extension could be an important process, even during non-flood events.

  12. Connecting Past to Present and Watersheds to Ocean: Modeling 165 Years of Incremental Changes to Flows into the San Francisco Bay Delta System

    Science.gov (United States)

    MacVean, L. J.; Thompson, S. E.; Huttom, P. H.; Sivapalan, M.

    2016-02-01

    California's Sacramento-San Joaquin Delta sits at the intersection of vast agricultural and population centers, and supplies fresh water for the diverse and often competing needs of ecosystems, farmers, and millions of Californians. Managing and allocating this resource is a complex feat of economics, politics, and engineering, made increasingly contentious by the ongoing drought. The objective of this research is to augment the scientific foundation of management decisions by addressing the question of how flows into the Delta have evolved in response to human intervention since 1850. In particular, quantifying the dynamic components of water usage through vegetative uptake and evapotranspiration, groundwater recharge, flood conveyance, and water exports at incremental levels of development is a key ambition. This approach emphasizes the built environment, which is subject to the local regulatory framework, rather than climate change, which is generally considered immovable without united global effort. This work encompasses the creation of a hydrologic model representing the watersheds of the San Francisco Bay-Delta system, and quantifies the impacts of changes in land use and the gradual construction of levees, reservoirs, and diversion infrastructure. The model is run using the same climatological forcing at each level of development, thus elucidating the effects of local anthropogenic activity on the Delta and the inflows to the San Francisco Bay estuary. Our results provide a timeline of change, giving decision-makers a scientifically established baseline to aid in the sustainable management of the Bay-Delta system.

  13. Danube Delta Coastline Dynamics in the Last 160 Years

    Science.gov (United States)

    Tătui, Florin; Vespremeanu-Stroe, Alfred; Constantinescu, Ştefan; Zăinescu, Florin

    2017-04-01

    prograding lobe, this resulted in the decrease with more than 75% of the progradation rates and with approximately 90% of the corresponding area change rates, marking its transition, since mid-20th century, from fluvial-dominated morphology to wave-influenced aspect and behaviour. Also, since the beginning of the 20th century, the asymmetric Sf. Gheorghe lobe (the other active lobe of the Danube), experienced dramatic changes of its millennial prograding pattern expressed by the complete cessation of the updrift coastal progradation and the prevalence of erosion in front of the river mouth, whose sediments are feeding far-positioned downdrift depocentres. These changes are reflected by the recent (1930s-present) river mouth dynamics, characterized by cessation of its long-term seaward expansion in favour of downdrift migration, indicating the transition of the Sf. Gheorghe mouth from an asymmetric to a deflected wave-influenced delta morphology. At multi-decadal scale, different modes of climate variability (e.g. North Atlantic Oscillation) control the storminess variations along the Danube Delta coast. Hence, active storminess during 1961-1979 time interval determined very high shoreline dynamics, with two-three times higher shoreline migration rates than afterwards, when a decrease in storminess favoured less dynamic coastlines (on both prograding and erosive sectors). At inter-annual scale, waterline mobility is influenced by storm regime and river floods. Our findings should support the sustainable coastal management and planning, providing a better understanding of past and present coastal processes along the Danube Delta coast.

  14. Modeling of GPS velocities across the Ganges-Brahmaputra Delta - Burma Arc oblique subduction system

    Science.gov (United States)

    Steckler, M. S.; Mondal, D. R.; Akhter, S. H.; Seeber, L.; Feng, L.; Gale, J.; Howe, M.; Masson, F.; Maurin, T.; Rangin, C.

    2014-12-01

    The Burma Arc is the northward continuation of the Sumatra-Anadaman subduction zone that gave rise to the 2004 M9.3 earthquake and tsunami. Near its northern end, it is colliding with the thick sediments of the Bengal Basin. The sediments of the Ganges-Brahmaputra Delta are folded and faulted, creating a subaerial 250-km wide accretionary prism. The deformation front is blind and reaches ½ way across the delta. Whether subduction is still occurring at this highly oblique plate boundary has been hotly debated. To investigate this, we combined our 25 continuous GPS receivers in Bangladesh with the campaign network in Myanmar, processing them together with GAMIT/GLOBK. We combined this data with 28 mostly campaign GPS sites in India (Gahalaut et al., 2012) by processing using the same IGS sites and performing a Helmert transformation to place all the data in same reference frame within ITRF2008. Published Indian plate poles yield a systematic residual for Bangladeshi sites believed to be on stable India. We estimated a new pole by combining 13 Indian stations (Mahesh et al., 2013) with 2 of our stations. Due to the rapid growth of the accretionary prism and the overthrusting by the Shillong Plateau, the Burma Arc changes shape from the backstop to the front folds. To project the GPS velocities into a profile, we have experimented with several projections that vary across the foldbelt, using the arc of the earthquakes and the topography as a guide. Strike-slip is mostly absorbed by the Sagaing and CMF faults, and some additional shear is distributed over the region. The best fitting suite of models for the shortening component yield 13-15 mm/y of shortening across the arc on a shallow-dipping megathrust. Additional shortening of ~4 mm/y is absorbed in the vicinity of the Kabaw Fault, where coverage is sparse. The dip of the megathrust and the depth of its downdip end trade off with one another in the different projections. The low range of dips of 6-10° is consistent

  15. Extracting a record of Holocene storm erosion and deposition preserved in the morphostratigraphy of a prograded coastal barrier

    Science.gov (United States)

    Dougherty, Amy J.

    2014-09-01

    Prograded barriers preserve palaeoenvironmental records within their varied morphologies and buried stratigraphy. In order to extract historical records of particular events, such as storms, the morphostratigraphy of these barriers must be detailed and the evolution deciphered. This study examines the progradation of Omaha barrier, New Zealand, using an integrated high-resolution geophysical and sedimentological approach. The barrier evolution appears complex, both spatially and temporally, with two different linear morphologies forming simultaneously alongshore, which both transition into a third type of ridge morphology across-shore. To determine what influenced the formation of these different morphologies, within the barrier and through time, various geological controls are investigated. The results are threefold: (1) a fall of sea level from a +2 m highstand drove barrier progradation, (2) differences in sediment supply driven by an exposure related longshore energy gradient dictated ridge morphology, and (3) storms punctuating barrier progradation formed the swales that define all morphologic ridges. High-energy events are recorded throughout the formation of Omaha barrier. Storm signatures are the most prominent features identified along the active beach and throughout the barrier morphostratigraphy. Observations of a high-energy event in 2007 document a unique depositional ridge emplaced landward of the characteristic erosional dune scarp and flattened beachface composed of course-grained/heavy mineral lag. A total of 25 paleo-beachfaces with the same post-storm geometry are identified within ground penetrating radar records of the barrier stratigraphy, including one associated with a known event in 1978 that has since been buried. Using limited ages available and the variable preservation of storm events in the morphostratigraphy, a speculative record of storm frequency and intensity is hypothesized. Future work aims to test this hypothesis by acquiring a

  16. Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

    Science.gov (United States)

    Castelino, Jude A.; Reichert, Christian; Jokat, Wilfried

    2017-09-01

    Submarine fans and turbidite systems are important and sensitive features located offshore from river deltas that archive tectonic events, regional climate, sea level variations and erosional process. Very little is known about the sedimentary structure of the 1800 km long and 400 km wide Mozambique Fan, which is fed by the Zambezi and spreads out into the Mozambique Channel. New multichannel seismic profiles in the Mozambique Basin reveal multiple feeder systems of the upper fan that have been active concurrently or consecutively since Late Cretaceous. We identify two buried, ancient turbidite systems off Mozambique in addition to the previously known Zambezi-Channel system and another hypothesized active system. The oldest part of the upper fan, located north of the present-day mouth of the Zambezi, was active from Late Cretaceous to Eocene times. Regional uplift caused an increased sediment flux that continued until Eocene times, allowing the fan to migrate southwards under the influence of bottom currents. Following the mid-Oligocene marine regression, the Beira High Channel-levee complex fed the Mozambique Fan from the southwest until Miocene times, reworking sediments from the shelf and continental slope into the distal abyssal fan. Since the Miocene, sediments have bypassed the shelf and upper fan region through the Zambezi Valley system directly into the Zambezi Channel. The morphology of the turbidite system off Mozambique is strongly linked to onshore tectonic events and the variations in sea level and sediment flux.

  17. Characterization of Fetal Antigen 1/Delta-Like 1 Homologue Expressing Cells in the Rat Nigrostriatal System

    DEFF Research Database (Denmark)

    Liechti, Rémy; Ducray, Angélique D; Jensen, Pia

    2015-01-01

    suggested as a potential supplementary marker of dopaminergic neurons. The present study aimed at investigating the distribution of FA1/dlk1-immunoreactive (-ir) cells in the early postnatal and adult midbrain as well as in the nigrostriatal system of 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian......Fetal antigen 1/delta-like 1 homologue (FA1/dlk1) belongs to the epidermal growth factor superfamily and is considered to be a non-canonical ligand for the Notch receptor. Interactions between Notch and its ligands are crucial for the development of various tissues. Moreover, FA1/dlk1 has been...... adult rats. FA1/dlk1-ir cells were predominantly distributed in the substantia nigra (SN) pars compacta (SNc) and in the ventral tegmental area. Interestingly, the expression of FA1/dlk1 significantly increased in tyrosine hydroxylase (TH)-ir cells during early postnatal development. Co...

  18. Tri-state delta modulation system for Space Shuttle digital TV downlink

    Science.gov (United States)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    1981-01-01

    Future requirements for Shuttle Orbiter downlink communication may include transmission of digital video which, in addition to black and white, may also be either field-sequential or NTSC color format. The use of digitized video could provide for picture privacy at the expense of additional onboard hardware, together with an increased bandwidth due to the digitization process. A general objective for the Space Shuttle application is to develop a digitization technique that is compatible with data rates in the 20-30 Mbps range but still provides good quality pictures. This paper describes a tri-state delta modulation/demodulation (TSDM) technique which is a good compromise between implementation complexity and performance. The unique feature of TSDM is that it provides for efficient run-length encoding of constant-intensity segments of a TV picture. Axiomatix has developed a hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV and field-sequential color. The hardware complexity of this TSDM implementation is summarized in the paper.

  19. Tri-state delta modulation system for Space Shuttle digital TV downlink

    Science.gov (United States)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    Future requirements for Shuttle Orbiter downlink communication may include transmission of digital video which, in addition to black and white, may also be either field-sequential or NTSC color format. The use of digitized video could provide for picture privacy at the expense of additional onboard hardware, together with an increased bandwidth due to the digitization process. A general objective for the Space Shuttle application is to develop a digitization technique that is compatible with data rates in the 20-30 Mbps range but still provides good quality pictures. This paper describes a tri-state delta modulation/demodulation (TSDM) technique which is a good compromise between implementation complexity and performance. The unique feature of TSDM is that it provides for efficient run-length encoding of constant-intensity segments of a TV picture. Axiomatix has developed a hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV and field-sequential color. The hardware complexity of this TSDM implementation is summarized in the paper.

  20. The inorganic chemistry of peat from the Maunachira channel-swamp system, Okavango Delta, Botswana

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, T.S.; McIver, J.R.; Cairncross, B.; Ellery, W.N.; Ellery, K.

    1989-05-01

    The Okavango Delta is a large (18000 km/sup 2/), low gradient (1:3600), alluvial fan situated in the semi-arid Kalahari basin of northern Botswana. Seasonal floodwaters from tropical Angola disperse on the fan creating both perennial (6000 km/sup 2/) and seasonal (7000 to 12000 km/sup 2/) swamps. Ninety-five percent of this water is lost annually by evapotranspiration. Organic rich sediment (peat) is a major sediment of the perennial swamps. Peat formation commences during senescence of the plants, when certain nutrients are recycled while others are lost by rainwater leaching. Further changes in chemistry occur during subaqueous decay of the plants which involve both gains and losses of constituents. Decaying plants trap detrital mineral matter which becomes an integral part of the peat. The main sources and forms of inorganic matter in the peat are: allochthonous kaolinite (40%) and quartz (20%) and both allochthonous and autochthonous phytolithic silica (30%). several inorganic components (Fe, K, P, Na, Ca and Mg) which make up the remaining 10% are associated with the organic fraction. Ion exchange plays only a minor part in their uptake and it seems that these metals are taken up during bacterial activity in the peat. The weight proportion of inorganic matter (ash) decreases downstream, mainly due to a decrease in allochthonous mineral matter. Volume percentage also decreases but is low throughout, generally less than five percent. This study has revealed that the low-quantity allochthonous mineral matter is the main reason for the long-term survival of this ecosystem. Uptake of soluble ions by the peat is important in off-setting evaporative concentration of metals. 36 refs., 13 figs., 7 tabs.

  1. Investigation of transient processes at the DELTA electron storage ring using a digital bunch-by-bunch feedback system

    Energy Technology Data Exchange (ETDEWEB)

    Hoener, Markus

    2015-07-01

    At the 1.5-GeV synchrotron radiation source DELTA, operated by the TU Dortmund University, intensive synchrotron radiation in the spectral range from hard X-rays to THz radiation is generated by the circular deflection of highly relativistic electron bunches. Interacting with the vacuum chamber wall, the electron bunches create electric fields, which can act back on subsequent bunches. With increasing beam current, the excitation is enhanced so that the electron beam is unstable, which means that the electron bunches oscillate longitudinally or transversely relative to their reference position. The oscillations reduce the quality of the synchrotron radiation and limit the maximum storable beam current. Within the scope of this thesis, the beam instabilities at the storage ring were systematically investigated. A digital bunch-by-bunch feedback system was installed and commissioned, which allows to detect and digitize the position of each electron bunch at each turn. Based on the input signal, a correction signal is calculated in order to suppress transverse and longitudinal oscillation of the bunches. In addition, it is possible to excite dedicated bunches. The systematic excitation of all coupled-bunch modes allowed for the first time to determine the damping rates of all 192 eigenmodes of the electron beam. The current dependence of the damping rates was investigated and an instability threshold was found. Besides the investigation of multibunch instabilities, single-bunch instabilities are discussed. In addition, the acquisition unit of the digital feedback system can be triggered on external events. This was used to investigate the injection process and beam losses. It was shown that the transverse feedback system increases the injection efficiency. Another aspect of this thesis is the improvement of the signal quality of ultrashort coherent synchrotron radiation pulses, which are generated by the short-pulse facility at DELTA. The short-pulse facility is based

  2. Infrastructure and Health Care Services in the Niger Delta Region of Nigeria: A Case Study of Physical Amenities in the Primary Health Care System in Delta State

    Directory of Open Access Journals (Sweden)

    Omuta GED

    2016-01-01

    Full Text Available Background: One of the spin-off effects of the urban-based medical services established by the colonial administration was the total neglect of rural communities. Those that existed lacked infrastructure. Even fifty years after independence, this dichotomy has persisted and become more pronounced. The objective of this study is to examine the state of infrastructure in the primary health care centres in Delta State, Nigeria. Methodology: The study was a survey of the infrastructure of all the PHC centres in nine local government areas; three from each of the three senatorial districts. The facilities covered were sources of water supply, sources of electricity, number of functional beds and type of communication facilities. The field date were cleaned up, processed and analysed using SPSS 10.0. Focus group discussions and key informant interviews were also conducted. In order to make the findings policy-relevant, a project steering committee made of researchers and decision makers and a project management committee made of representatives of decision makers, care providers, care seekers and other stakeholders were se up and integrated into the study. Results: There were varying degrees of infrastructural deficiencies. 34.22 per cent of the PHCs had no access to safe water; 51.33 per cent were not connected to the national electricity grid; and 34.22 per cent of the available beds and 40.89 per cent no means of communication whatsoever. Conclusion: Field data and perspectives of stakeholders revealed that the major cause of infrastructural deficiencies was insufficient funding, lopsided allocation of resources and official corruption. Correspondingly, increased and sustained funding; prioritized allocation of resources and targeted upgrading of facilities, were recommended.

  3. Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system.

    Science.gov (United States)

    Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

    2014-03-01

    Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

  4. The endocannabinoid system and emotional processing: A pharmacological fMRI study with Delta 9-tetrahydrocannabinol

    NARCIS (Netherlands)

    Bossong, M.G.; Hell, van H.H.; Jager, G.; Kahn, R.S.; Ramsey, N.F.; Jansma, J.M.

    2013-01-01

    Various psychiatric disorders such as major depression are associated with abnormalities in emotional processing. Evidence indicating involvement of the endocannabinoid system in emotional processing, and thus potentially in related abnormalities, is increasing. In the present study, we examined the

  5. How can climate change and engineered water conveyance affect sediment dynamics in the San Francisco Bay-Delta system?

    Science.gov (United States)

    Achete, Fernanda; Van der Wegen, Mick; Roelvink, Jan Adriaan; Jaffe, Bruce E.

    2017-01-01

    Suspended sediment concentration is an important estuarine health indicator. Estuarine ecosystems rely on the maintenance of habitat conditions, which are changing due to direct human impact and climate change. This study aims to evaluate the impact of climate change relative to engineering measures on estuarine fine sediment dynamics and sediment budgets. We use the highly engineered San Francisco Bay-Delta system as a case study. We apply a process-based modeling approach (Delft3D-FM) to assess the changes in hydrodynamics and sediment dynamics resulting from climate change and engineering scenarios. The scenarios consider a direct human impact (shift in water pumping location), climate change (sea level rise and suspended sediment concentration decrease), and abrupt disasters (island flooding, possibly as the results of an earthquake). Levee failure has the largest impact on the hydrodynamics of the system. Reduction in sediment input from the watershed has the greatest impact on turbidity levels, which are key to primary production and define habitat conditions for endemic species. Sea level rise leads to more sediment suspension and a net sediment export if little room for accommodation is left in the system due to continuous engineering works. Mitigation measures like levee reinforcement are effective for addressing direct human impacts, but less effective for a persistent, widespread, and increasing threat like sea level rise. Progressive adaptive mitigation measures to the changes in sediment and flow dynamics resulting from sea level rise may be a more effective strategy. Our approach shows that a validated process-based model is a useful tool to address long-term (decades to centuries) changes in sediment dynamics in highly engineered estuarine systems. In addition, our modeling approach provides a useful basis for long-term, process-based studies addressing ecosystem dynamics and health.

  6. Investigation of Presage 3D Dosimetry as a Method of Clinically Intuitive Quality Assurance and Comparison to a Semi-3D Delta4 System

    Science.gov (United States)

    Crockett, Ethan Van

    The need for clinically intuitive metrics for patient-specific quality assurance in radiation therapy has been well-documented (Zhen, Nelms et al. 2011). A novel transform method has shown to be effective at converting full-density 3D dose measurements made in a phantom to dose values in the patient geometry, enabling comparisons using clinically intuitive metrics such as dose-volume histograms (Oldham et al. 2011). This work investigates the transform method and compares its calculated dose-volume histograms (DVHs) to DVH values calculated by a Delta4 QA device (Scandidos), marking the first comparison of a true 3D system to a semi-3D device using clinical metrics. Measurements were made using Presage 3D dosimeters, which were readout by an in-house optical-CT scanner. Three patient cases were chosen for the study: one head-and-neck VMAT treatment and two spine IMRT treatments. The transform method showed good agreement with the planned dose values for all three cases. Furthermore, the transformed DVHs adhered to the planned dose with more accuracy than the Delta4 DVHs. The similarity between the Delta4 DVHs and the transformed DVHs, however, was greater for one of the spine cases than it was for the head-and-neck case, implying that the accuracy of the Delta4 Anatomy software may vary from one treatment site to another. Overall, the transform method, which incorporates data from full-density 3D dose measurements, provides clinically intuitive results that are more accurate and consistent than the corresponding results from a semi-3D Delta 4 system.

  7. Behaviour of {alpha}-, {beta}-, {gamma}-, and {delta}-hexachlorocyclohexane in the soil-plant system of a contaminated site

    Energy Technology Data Exchange (ETDEWEB)

    Calvelo Pereira, R. [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, Universidade de Santiago de Compostela, 15782-Santiago de Compostela (Spain)]. E-mail: edrobert@usc.es; Camps-Arbestain, M. [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, Universidade de Santiago de Compostela, 15782-Santiago de Compostela (Spain); Rodriguez Garrido, B. [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, Universidade de Santiago de Compostela, 15782-Santiago de Compostela (Spain); Macias, F. [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, Universidade de Santiago de Compostela, 15782-Santiago de Compostela (Spain); Monterroso, C. [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, Universidade de Santiago de Compostela, 15782-Santiago de Compostela (Spain)

    2006-11-15

    The behaviour of the organochlorine pesticide hexachlorocyclohexane (HCH) is investigated. The concentrations of {alpha}-, {beta}-, {gamma}-, and {delta}-HCH isomers were measured in soils, rhizosphere and vegetation in a contaminated area in Galicia (NW Spain). The total concentration of HCH in soils reached values close to 20 000 mg kg{sup -1}. The plants analysed (Avena sativa L., Chenopodium spp., Solanum nigrum L., Cytisus striatus (Hill) Roth, and Vicia sativa L.) accumulated HCH, especially the {beta}-HCH isomer, in their tissues. The most likely mechanisms of HCH accumulation in plants were sorption of soil HCH on roots and sorption of volatilized HCH on aerial plant tissues. The concentrations of HCH obtained from the bulk and rhizosphere soils of selected plant species suggest that roots tend to reduce levels of the HCH isomers in the rhizosphere. The results reflect the importance of vegetation in the distribution of organochlorine compounds in the soil-plant system. - This paper describes the soil-plant relationship of hexachlorocyclohexane isomers in a contaminated site, with special focus on the rhizosphere effect.

  8. The forecasting research of early warning systems for atmospheric pollutants: A case in Yangtze River Delta region

    Science.gov (United States)

    Song, Yiliao; Qin, Shanshan; Qu, Jiansheng; Liu, Feng

    2015-10-01

    The issue of air quality regarding PM pollution levels in China is a focus of public attention. To address that issue, to date, a series of studies is in progress, including PM monitoring programs, PM source apportionment, and the enactment of new ambient air quality index standards. However, related research concerning computer modeling for PM future trends estimation is rare, despite its significance to forecasting and early warning systems. Thereby, a study regarding deterministic and interval forecasts of PM is performed. In this study, data on hourly and 12 h-averaged air pollutants are applied to forecast PM concentrations within the Yangtze River Delta (YRD) region of China. The characteristics of PM emissions have been primarily examined and analyzed using different distribution functions. To improve the distribution fitting that is crucial for estimating PM levels, an artificial intelligence algorithm is incorporated to select the optimal parameters. Following that step, an ANF model is used to conduct deterministic forecasts of PM. With the identified distributions and deterministic forecasts, different levels of PM intervals are estimated. The results indicate that the lognormal or gamma distributions are highly representative of the recorded PM data with a goodness-of-fit R2 of approximately 0.998. Furthermore, the results of the evaluation metrics (MSE, MAPE and CP, AW) also show high accuracy within the deterministic and interval forecasts of PM, indicating that this method enables the informative and effective quantification of future PM trends.

  9. Systemic down-regulation of delta-9 desaturase promotes muscle oxidative metabolism and accelerates muscle function recovery following nerve injury.

    Directory of Open Access Journals (Sweden)

    Ghulam Hussain

    Full Text Available The progressive deterioration of the neuromuscular axis is typically observed in degenerative conditions of the lower motor neurons, such as amyotrophic lateral sclerosis (ALS. Neurodegeneration in this disease is associated with systemic metabolic perturbations, including hypermetabolism and dyslipidemia. Our previous gene profiling studies on ALS muscle revealed down-regulation of delta-9 desaturase, or SCD1, which is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Interestingly, knocking out SCD1 gene is known to induce hypermetabolism and stimulate fatty acid beta-oxidation. Here we investigated whether SCD1 deficiency can affect muscle function and its restoration in response to injury. The genetic ablation of SCD1 was not detrimental per se to muscle function. On the contrary, muscles in SCD1 knockout mice shifted toward a more oxidative metabolism, and enhanced the expression of synaptic genes. Repressing SCD1 expression or reducing SCD-dependent enzymatic activity accelerated the recovery of muscle function after inducing sciatic nerve crush. Overall, these findings provide evidence for a new role of SCD1 in modulating the restorative potential of skeletal muscles.

  10. Systemic Down-Regulation of Delta-9 Desaturase Promotes Muscle Oxidative Metabolism and Accelerates Muscle Function Recovery following Nerve Injury

    Science.gov (United States)

    Henriques, Alexandre; Lequeu, Thiebault; Rene, Frederique; Bindler, Françoise; Dirrig-Grosch, Sylvie; Oudart, Hugues; Palamiuc, Lavinia; Metz-Boutigue, Marie-Helene; Dupuis, Luc; Marchioni, Eric; Gonzalez De Aguilar, Jose-Luis; Loeffler, Jean-Philippe

    2013-01-01

    The progressive deterioration of the neuromuscular axis is typically observed in degenerative conditions of the lower motor neurons, such as amyotrophic lateral sclerosis (ALS). Neurodegeneration in this disease is associated with systemic metabolic perturbations, including hypermetabolism and dyslipidemia. Our previous gene profiling studies on ALS muscle revealed down-regulation of delta-9 desaturase, or SCD1, which is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Interestingly, knocking out SCD1 gene is known to induce hypermetabolism and stimulate fatty acid beta-oxidation. Here we investigated whether SCD1 deficiency can affect muscle function and its restoration in response to injury. The genetic ablation of SCD1 was not detrimental per se to muscle function. On the contrary, muscles in SCD1 knockout mice shifted toward a more oxidative metabolism, and enhanced the expression of synaptic genes. Repressing SCD1 expression or reducing SCD-dependent enzymatic activity accelerated the recovery of muscle function after inducing sciatic nerve crush. Overall, these findings provide evidence for a new role of SCD1 in modulating the restorative potential of skeletal muscles. PMID:23785402

  11. Performance comparison among the major healthcare financing systems in six cities of the Pearl River Delta region, mainland China.

    Science.gov (United States)

    Wong, Martin C S; Wang, Harry H X; Wong, Samuel Y S; Wei, Xiaolin; Yang, Nan; Zhang, Zhenzhen; Li, Haitao; Gao, Yang; Li, Donald K T; Tang, Jinling; Wang, Jiaji; Griffiths, Sian M

    2012-01-01

    The healthcare system of mainland China is undergoing drastic reform and the optimal models for healthcare financing for provision of primary care will need to be identified. This study compared the performance indicators of the community health centres (CHCs) under different healthcare financing systems in the six cities of the Pearl River Delta region. Approximately 300 hypertensive patients were randomly recruited from the computerized chronic disease management records provided by one CHC in each of the six cities in 2011 using a multi-stage cluster random sampling method. The major outcome measures included the treatment rate of hypertension, defined as prescription of ≥ one antihypertensive agent; and the control rate of hypertension, defined as systolic blood pressure levels logistic regression analyses were conducted with these two measures as outcome variables, respectively, controlling for patients' socio-demographic variables. The financing system (Hospital- vs. Government- vs. private-funded) was the independent variable tested for association with the outcomes. From 1,830 patients with an average age of 65.9 years (SD 12.8), the overall treatment and control rates were 75.4% and 20.2%, respectively. When compared with hospital-funded CHCs, patients seen in the Government-funded (adjusted odds ratio [AOR] 0.462, 95% C.I. 0.325-0.656) and private-funded CHCs (AOR 0.031, 95% C.I. 0.019-0.052) were significantly less likely to be prescribed antihypertensive medication. However, the Government-funded CHC was more likely to have optimal BP control (AOR 1.628, 95% C.I. 1.157-2.291) whilst the privately-funded CHC was less likely to achieve BP control (AOR 0.146, 95% C.I. 0.069-0.310), irrespective of whether antihypertensive drugs were prescribed. Privately-funded CHCs had the lowest rates of BP treatment and control due to a variety of potential factors as discussed.

  12. Seismic analysis of linked geological processes in the transitional domain of gravity detachment systems: deepwater western Nigeria delta

    Science.gov (United States)

    Leduc, Amelie

    Two and three-dimensional seismic data are used to investigate some stratigraphic relationships between sedimentation, deformation and fluid flow at the lateral margin of a gravity detachment system. Three themes were studied. In the Niger Delta, a right-lateral strike-slip fault with a displacement of around 7 km occurs across 75 km. It is interpreted as the lateral strike-slip domain, linked to the updip extensional domain and the downdip compression zone of a gravity detachment system. Structural and kinematic evidence, such as present-day propagating strike-slip faults, for possible future lateral expansions of the lateral strike-slip domain, is described. We expect to observe similar domains at the margins of other preserved gravitational collapse sliding over a detachment whose efficiency in causing downdip slip may vary laterally. Using 3D data from both Mauritania and Nigeria, the interactions between tear faults and deepwater channels are studied. Structural observations combined with channel analysis are performed in four case studies, illustrating that tear faults influence channel development throughout their evolution. Some examples across tear fault zones are presented, and it is expected to find such interactions elsewhere in the world. A simple model of development of vertical fluid flow pipes is established using two examples that are 400 - 600 m wide and ~ 2000 - 2500 m high. Both examples are located at the crest of rollover anticlines and rooted in buried channel-complexes tilted during fold growth. At the crest of the structures and within the connected permeable reservoir intervals of the channel complexes, lateral pressure transfer caused the pore pressure to reach critical levels, leading to hydraulic fracturing of the overburden. Although hydrocarbons may migrate upwards through the consequent chimney systems, the pipes are not necessarily indicators of hydrocarbon charge of the channel complexes.

  13. The Delta 2 launcher

    Science.gov (United States)

    Ousley, Gilbert W., Sr.

    1991-12-01

    The utilization of the Delta 2 as the vehicle for launching Aristoteles into its near Sun synchronous orbit is addressed. Delta is NASA's most reliable launch vehicle and is well suited for placing the present Aristoteles spacecraft into a 400 m circular orbit. A summary of some of the Delta 2 flight parameters is presented. Diagrams of a typical Delta 2 two stage separation are included along with statistics on delta reliability and launch plans.

  14. System Level Design of a Continuous-Time Delta-Sigma Modulator for Portable Ultrasound Scanners

    OpenAIRE

    Llimos Muntal, Pere; Færch, Kjartan; Jørgensen, Ivan Harald Holger; Bruun, Erik

    2015-01-01

    In this paper the system level design of a continuous-time ∆Σ modulator for portable ultrasound scanners is presented. The overall required signal-to-noise ratio (SNR) is derived to be 42 dB and the sampling frequency used is 320 MHz for an oversampling ratio of 16. In order to match these requirements, a fourth order, 1-bit modulator with optimal zero placing is used. An analysis shows that the thermal noise from the resistors and operational transconductance amplifier is not a limiting fact...

  15. System Level Design of a Continuous-Time Delta-Sigma Modulator for Portable Ultrasound Scanners

    DEFF Research Database (Denmark)

    Llimos Muntal, Pere; Færch, Kjartan; Jørgensen, Ivan Harald Holger

    2015-01-01

    these requirements, a fourth order, 1-bit modulator with optimal zero placing is used. An analysis shows that the thermal noise from the resistors and operational transconductance amplifier is not a limiting factor due to the low required SNR, leading to an inherently very low-power implementation. Furthermore......In this paper the system level design of a continuous-time ∆Σ modulator for portable ultrasound scanners is presented. The overall required signal-to-noise ratio (SNR) is derived to be 42 dB and the sampling frequency used is 320 MHz for an oversampling ratio of 16. In order to match...

  16. THE ECONOMIC AND PHYSICAL ASPECTS OF THE URBANISTIC PROCESS IN THE PEARL RIVER DELTA: The management system of the Urban Historic Conservation Area in the megalopolis.

    OpenAIRE

    Xu, Haohao

    2010-01-01

    The thesis THE ECONOMIC AND PHYSICAL ASPECTS OF THE URBANISTIC PROCESS IN THE PEARL RIVER DELTA: The management system of the Urban Historic Conservation Area in the megalopolis is based on the background of urbanistic development in Southern China in the last 30 years. China experiences reform and open policy since the beginning of 1980, comprehensive urbanization in the 1990s and the great change of the dualistic mechanism after 2000. It is the greatest urbanization proces...

  17. Carbon storage in the Mississippi River delta enhanced by environmental engineering

    Science.gov (United States)

    Shields, Michael R.; Bianchi, Thomas S.; Mohrig, David; Hutchings, Jack A.; Kenney, William F.; Kolker, Alexander S.; Curtis, Jason H.

    2017-11-01

    River deltas have contributed to atmospheric carbon regulation throughout Earth history, but functioning in the modern era has been impaired by reduced sediment loads, altered hydrologic regimes, increased global sea-level rise and accelerated subsidence. Delta restoration involves environmental engineering via river diversions, which utilize self-organizing processes to create prograding deltas. Here we analyse sediment cores from Wax Lake delta, a product of environmental engineering, to quantify the burial of organic carbon. We find that, despite relatively low concentrations of organic carbon measured in the cores (about 0.4%), the accumulation of about 3 T m-2 of sediment over the approximate 60 years of delta building resulted in the burial of a significant amount of organic carbon (16 kg m-2). This equates to an apparent organic carbon accumulation rate of 250 +/- 23 g m-2 yr-1, which implicitly includes losses by carbon emissions and erosion. Our estimated accumulation rate for Wax Lake delta is substantially greater than previous estimates based on the top metre of delta sediments and comparable to those of coastal mangrove and marsh habitats. The sedimentation of carbon at the Wax Lake delta demonstrates the capacity of engineered river diversions to enhance both coastal accretion and carbon burial.

  18. Evaluation of water distribution under pivot irrigation systems using remote sensing imagery in eastern Nile delta

    Directory of Open Access Journals (Sweden)

    E. Farg

    2017-04-01

    Full Text Available Traditional methods for center pivot evaluation depend on the water depth distribution along the pivot arm. Estimation and mapping the water depth under pivot irrigation systems using remote sensing data is essential for calculating the coefficient of uniformity (CU of water distribution. This study focuses on estimating and mapping water depth using Landsat OLI 8 satellite data integrated with Heerman and Hein (1968 modified equation for center pivot evaluation. Landsat OLI 8 image was geometrically and radiometrically corrected to calculate the vegetation and water indices (NDVI and NDWI in addition to land surface temperature. Results of the statistical analysis showed that the collected water depth in catchment cans is also highly correlated negatively with NDVI. On the other hand water, depth was positively correlated with NDWI and LST. Multi-linear regression analysis using stepwise selection method was applied to estimate and map the water depth distribution. The results showed R2 and adjusted R2 0.93 and 0.88 respectively. Study area or field level verification was applied for estimation equation with correlation 0.93 between the collected water depth and estimated values.

  19. Delta-Sigma AD-Converters Practical Design for Communication Systems

    CERN Document Server

    Gaggl, Richard

    2013-01-01

    The emphasis of this book is on practical design aspects for broadband A/D converters for communication systems. The embedded designs are employed for transceivers in the field of ADSL solutions and WLAN applications. An area- and power-efficient realization of a converter is mandatory to remain competitive in the market. The right choice for the converter topology and architecture needs to be done very carefully to result in a competitive FOM. The book begins with a brief overview of basic concepts about ADSL and WLAN to understand the ADC requirements. At architectural level, issues on different modulator topologies are discussed employing the provided technology node. The design issues are pointed out in detail for modern digital CMOS technologies, beginning with 180nm followed by 130nm and going down to 65nm feature size. Beside practical aspects, challenges to mixed-signal design level are addressed to optimize the converters in terms of consumed chip area, power consumption and design for high yield in ...

  20. Climate Variability over India and Bangladesh from the Perturbed UK Met Office Hadley Model: Impacts on Flow and Nutrient Fluxes in the Ganges Delta System

    Science.gov (United States)

    Whitehead, P. G.; Caesar, J.; Crossman, J.; Barbour, E.; Ledesma, J.; Futter, M. N.

    2015-12-01

    A semi-distributed flow and water quality model (INCA- Integrated Catchments Model) has been set up for the whole of the Ganges- Brahmaputra- Meghna (GBM) River system in India and Bangladesh. These massive rivers transport large fluxes of water and nutrients into the Bay of Bengal via the GBM Delta system in Bangladesh. Future climate change will impact these fluxes with changing rainfall, temperature, evapotranspiration and soil moisture deficits being altered in the catchment systems. In this study the INCA model has been used to assess potential impacts of climate change using the UK Met Office Hadley Centre GCM model linked to a regionally coupled model of South East Asia, covering India and Bangladesh. The Hadley Centre model has been pururbed by varying the parameters in the model to generate 17 realisations of future climates. Some of these reflect expected change but others capture the more extreme potential behaviour of future climate conditions. The 17 realisations have been used to drive the INCA Flow and Nitrogen model inorder to generate downstream times series of hydrology and nitrate- nitrogen. The variability of the climates on these fluxes are investigated and and their likley impact on the Bay of Begal Delta considered. Results indicate a slight shift in the monsoon season with increased wet season flows and increased temperatures which alter nutrient fluxes. Societal Importance to Stakeholders The GBM Delta supports one of the most densely populated regions of people living in poverty, who rely on ecosystem services provided by the Delta for survival. These ecosystem services are dependent upon fluxes of water and nutrients. Freshwater for urban, agriculture, and aquaculture requirements are essential to livelihoods. Nutrient loads stimulate estuarine ecosystems, supporting fishing stocks, which contribute significantly the economy of Bangladesh. Thus the societal importance of upstream climate driven change change in Bangladesh are very

  1. Evolving deltas: Conceptualising coevolution with engineered interventions

    Science.gov (United States)

    Welch, Amy; Nicholls, Robert; Lazar, Attila

    2017-04-01

    Mid to low latitude deltas have been populated for thousands of years due to their fertile soil and coastal location. This has led to an alteration in the land cover of deltas to primary agriculture and dense rural settlements and more recently, major cities and megacities have developed on or adjacent to many deltas. Deltas may be prosperous in terms of their outputs and services; however, they are also susceptible to many hazards due to their location and low-lying nature. Hazards include storm surges, fluvial flooding and erosion of both coastal and riverine areas, as well as subsidence, relative sea-level rise and pollution. This can have severe impacts on the delta, its population and its services. Therefore engineered interventions have been used for some time to protect the population and the valuable land from the consequences of hazards. Coevolution can be described as a feedback loop between nature and humans: each has an effect on how the other behaves and hence this inter-dependence interaction continues. Therefore the natural evolution of the delta interacts with engineered interventions, such as promoting accelerated subsidence over time, necessitating further adaptation. The deltaic landscape and associated livelihoods are thus the result of this co-evolution process between natural delta processes and engineered interventions. This presentation will identify and discuss various drivers and consequences of large scale engineered interventions, comparing and contrasting the management approaches taken in five populated deltas (Ganges-Brahmaputra-Meghna, Yangtze, Rhine-Meuse-Scheldt, Mekong and Nile). The type of engineered intervention and management approaches had a direct effect on the coevolution of deltas, with each of the deltas being at different stages in terms of extent of coevolution. A qualitative timeline of the typical steps of coevolution between the human system and the delta system of the studied deltas was produced. The major

  2. Water and nutrient budgets of ponds in integrated agriculture-aquaculture systems in the Mekong Delta, Vietnam.

    NARCIS (Netherlands)

    Nhan, D.K.; Verdegem, M.C.J.; Milstein, A.; Verreth, J.A.J.

    2008-01-01

    A participatory on-farm study analysed water and nutrient budgets of six low and four high water-exchange ponds of integrated agriculture-aquaculture (IAA) farms in the Mekong delta. Water, nitrogen (N), organic carbon (OC) and phosphorus (P) flows through the ponds were monitored, and data on fish

  3. Implementation of Geographic Information Systems for a Nigerian State: A Case Study of the Catholic Dioceses of Delta State

    Science.gov (United States)

    Banye, Anthony

    2011-01-01

    There is an understandable concern among practitioners of education, academic analysts, policy formulators, and curriculum designers that a large number of government officials have both neglected and ignored the salient topic of the changing demographics of Nigeria and of Delta State (NPC, 2007). The economic upturn of Nigeria and in particular…

  4. Performance comparison among the major healthcare financing systems in six cities of the Pearl River Delta region, mainland China.

    Directory of Open Access Journals (Sweden)

    Martin C S Wong

    Full Text Available BACKGROUND: The healthcare system of mainland China is undergoing drastic reform and the optimal models for healthcare financing for provision of primary care will need to be identified. This study compared the performance indicators of the community health centres (CHCs under different healthcare financing systems in the six cities of the Pearl River Delta region. METHODS: Approximately 300 hypertensive patients were randomly recruited from the computerized chronic disease management records provided by one CHC in each of the six cities in 2011 using a multi-stage cluster random sampling method. The major outcome measures included the treatment rate of hypertension, defined as prescription of ≥ one antihypertensive agent; and the control rate of hypertension, defined as systolic blood pressure levels <140 mmHg and diastolic blood pressure levels <90 mmHg in patients without diabetes mellitus, or <130/80 mmHg among patients with concomitant diabetes. Binary logistic regression analyses were conducted with these two measures as outcome variables, respectively, controlling for patients' socio-demographic variables. The financing system (Hospital- vs. Government- vs. private-funded was the independent variable tested for association with the outcomes. RESULTS: From 1,830 patients with an average age of 65.9 years (SD 12.8, the overall treatment and control rates were 75.4% and 20.2%, respectively. When compared with hospital-funded CHCs, patients seen in the Government-funded (adjusted odds ratio [AOR] 0.462, 95% C.I. 0.325-0.656 and private-funded CHCs (AOR 0.031, 95% C.I. 0.019-0.052 were significantly less likely to be prescribed antihypertensive medication. However, the Government-funded CHC was more likely to have optimal BP control (AOR 1.628, 95% C.I. 1.157-2.291 whilst the privately-funded CHC was less likely to achieve BP control (AOR 0.146, 95% C.I. 0.069-0.310, irrespective of whether antihypertensive drugs were prescribed. CONCLUSIONS

  5. Development of a decision support system for individual dairy farms in mixed irrigated farming systems in the Nile Delta

    NARCIS (Netherlands)

    Tabana, A.

    2000-01-01

    The principal animal production system in Egypt is the mixed crop-livestock production system with a semi-intensive/semi-commercial orientation. The development strategies emphasized in this study contribute to the development and implementation of improved

  6. Delta Plaza kohvik = Delta Plaza cafe

    Index Scriptorium Estoniae

    2010-01-01

    Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

  7. Reaction-induced grain boundary cracking and anisotropic fluid flow during prograde devolatilization reactions within subduction zones

    Science.gov (United States)

    Okamoto, Atsushi; Shimizu, Hiroyuki; Fukuda, Jun-ichi; Muto, Jun; Okudaira, Takamoto

    2017-09-01

    Devolatilization reactions during prograde metamorphism are a key control on the fluid distribution within subduction zones. Garnets in Mn-rich quartz schist within the Sanbagawa metamorphic belt of Japan are characterized by skeletal structures containing abundant quartz inclusions. Each quartz inclusion was angular-shaped, and showed random crystallographic orientations, suggesting that these quartz inclusions were trapped via grain boundary cracking during garnet growth. Such skeletal garnet within the quartz schist formed related to decarbonation reactions with a positive total volume change (Δ V t > 0), whereas the euhedral garnet within the pelitic schists formed as a result of dehydration reaction with negative Δ V t values. Coupled hydrological-chemical-mechanical processes during metamorphic devolatilization reactions were investigated by a distinct element method (DEM) numerical simulation on a foliated rock that contained reactive minerals and non-reactive matrix minerals. Negative Δ V t reactions cause a decrease in fluid pressure and do not produce fractures within the matrix. In contrast, a fluid pressure increase by positive Δ V t reactions results in hydrofracturing of the matrix. This fracturing preferentially occurs along grain boundaries and causes episodic fluid pulses associated with the development of the fracture network. The precipitation of garnet within grain boundary fractures could explain the formation of the skeletal garnet. Our DEM model also suggests a strong influence of reaction-induced fracturing on anisotropic fluid flow, meaning that dominant fluid flow directions could easily change in response to changes in stress configuration and the magnitude of differential stress during prograde metamorphism within a subduction zone.

  8. Prograde metamorphic evolution and development of chloritoid-bearing eclogitic assemblages in subcontinental metagabbro (Sesia Lanzo zone, Italy)

    Science.gov (United States)

    Rebay, G.; Messiga, B.

    2007-10-01

    In the coronitic metagabbroic rocks of the Corio and Monastero metagabbro bodies in the continental Sesia-Lanzo zone of the western Italian Alps, a variety of mineral reactions that testify to prograde conditions from greenschist to eclogite-facies can be recognised. A microstructural and microchemical study of a series of samples characterized by coronitic textures and pseudomorphic replacement of the original igneous minerals has allowed the prograde reactions undergone by the rocks to be established. In completely eclogitized coronitic samples, paragonite, blue amphibole, garnet, epidote, fine grained jadeite and chloritoid occur in plagioclase microdomains (former igneous plagioclase). The mafic mineral microdomains consist of glaucophane and garnet. Complexly-zoned amphiboles constrain changing metamorphic conditions: cores of pre-Alpine brown hornblende and/or tremolite are preserved inside rims of a sodic-calcic amphibole that are in turn surrounded by a sodic amphibole. The main high-pressure mineral assemblage, as seen in mylonites, involves glaucophane, chloritoid, epidote, garnet ± phengite, ± paragonite. Some layers within the gabbro contain garnet, omphacite, ± glaucophane, and acid dykes crosscutting the gabbro body contain jadeite, quartz, garnet, epidote and paragonite. The presence of chloritoid-bearing high-pressure assemblages reflects hydration of the gabbros during their pre-Alpine exhumation prior to subduction, as well as the composition of the microdomains operating during subduction. The pressure and temperature conditions of gabbro transformation during subduction are inferred to be 450-550 °C at up to 2 GPa on the basis of the chloritoid-bearing assemblages. The factors controlling the reaction pathway to form chloritoid-bearing high-pressure assemblages in mafic rocks are inferred from these observations.

  9. delta-vision

    Data.gov (United States)

    California Department of Resources — Delta Vision is intended to identify a strategy for managing the Sacramento-San Joaquin Delta as a sustainable ecosystem that would continue to support environmental...

  10. Trends in major risk factors for cardiovascular disease among adults in the Mississippi Delta region, Mississippi Behavioral Risk Factor Surveillance System, 2001-2010.

    Science.gov (United States)

    Mendy, Vincent L; Vargas, Rodolfo

    2015-02-19

    The prevalences of major modifiable risk factors for cardiovascular disease (CVD) are disproportionately high in the 18-county Mississippi Delta region, and many of these risk factors disproportionately affect blacks. Temporal trends in the prevalence of CVD risk factors in the Mississippi Delta have not been determined. We examined trends in CVD risk factors from 2001 to 2010 in the region. Longitudinal trends in prevalence of high blood pressure, high cholesterol, diabetes, obesity, physical inactivity, and current smoking were investigated using self-reported data from the Behavioral Risk Factor Surveillance System. Joinpoint regression models were used to examine annual percentage change (APC) in the prevalence of these risk factors. Overall, from 2001 to 2010, we observed significant increases in the prevalence of high cholesterol (APC, 4.22%), obesity (APC, 3.65%), and diabetes (APC, 3.54%). Among blacks, we found significant increases in the prevalence of high cholesterol (APC, 3.41%), obesity (APC, 3.48%), and diabetes (APC, 4.96%). Among whites, we found significant increases in high blood pressure (APC, 2.18%), high cholesterol (APC, 4.78%), obesity (APC, 4.18%), and physical inactivity (APC, 3.06%). We also observed a significant decrease in smoking among whites (APC, -1.99%). From 2001 to 2010, we found a significant increase in the prevalence of high cholesterol, diabetes, and obesity in the Mississippi Delta. We also observed racial differences in those prevalences.

  11. 3D architecture of cyclic-step and antidune deposits in glacigenic subaqueous fan and delta settings: Integrating outcrop and ground-penetrating radar data

    Science.gov (United States)

    Lang, Jörg; Sievers, Julian; Loewer, Markus; Igel, Jan; Winsemann, Jutta

    2017-12-01

    Bedforms related to supercritical flows are increasingly recognised as important constituents of many depositional environments, but outcrop studies are commonly hampered by long bedform wavelengths and complex three-dimensional geometries. We combined outcrop-based facies analysis with ground-penetrating radar (GPR) surveys to analyse the 3D facies architecture of subaqueous ice-contact fan and glacifluvial delta deposits. The studied sedimentary systems were deposited at the margins of the Middle Pleistocene Scandinavian ice sheets in Northern Germany. Glacifluvial Gilbert-type deltas are characterised by steeply dipping foreset beds, comprising cyclic-step deposits, which alternate with antidune deposits. Deposits of cyclic steps consist of lenticular scours infilled by backset cross-stratified pebbly sand and gravel. The GPR sections show that the scour fills form trains along the delta foresets, which can locally be traced for up to 15 m. Perpendicular and oblique to palaeoflow direction, these deposits appear as troughs with concentric or low-angle cross-stratified infills. Downflow transitions from scour fills into sheet-like low-angle cross-stratified or sinusoidally stratified pebbly sand, deposited by antidunes, are common. Cyclic steps and antidunes were deposited by sustained and surge-type supercritical density flows, which were related to hyperpycnal flows, triggered by major meltwater discharge or slope-failure events. Subaqueous ice-contact fan deposits include deposits of progradational scour fills, isolated hydraulic jumps, antidunes and (humpback) dunes. The gravel-rich fan succession consists of vertical stacks of laterally amalgamated pseudo-sheets, indicating deposition by pulses of waning supercritical flows under high aggradation rates. The GPR sections reveal the large-scale architecture of the sand-rich fan succession, which is characterised by lobe elements with basal erosional surfaces associated with scours filled with backsets related

  12. Characterization of a prototype MR-compatible Delta4 QA system in a 1.5 tesla MR-linac

    Science.gov (United States)

    de Vries, J. H. W.; Seravalli, E.; Houweling, A. C.; Woodings, S. J.; van Rooij, R.; Wolthaus, J. W. H.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2018-01-01

    To perform patient plan quality assurance (QA) on a newly installed MR-linac (MRL) it is necessary to have an MR-compatible QA device. An MR compatible device (MR-Delta4) has been developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response, such as short-term reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency, were investigated for the clinical Delta4-PT as well as for the MR compatible version. All tests were performed with both devices on a conventional linac and the MR compatible device was tested on the MRL as well. No statistically significant differences were found in the short-term reproducibility (prototype was found to be safe and effective for use in the 1.5 tesla magnetic field of the Elekta MR-linac

  13. Delta Blues Scholarship and Imperialist Nostalgia.

    Science.gov (United States)

    Nye, William P.

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

  14. Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

    DEFF Research Database (Denmark)

    Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine

    2017-01-01

    the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers......, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together...

  15. Autoradiographic localization of delta opioid receptors within the mesocorticolimbic dopamine system using radioiodinated (2-D-penicillamine, 5-D-penicillamine)enkephalin ( sup 125 I-DPDPE)

    Energy Technology Data Exchange (ETDEWEB)

    Dilts, R.P.; Kalivas, P.W. (Washington State Univ., Pullman (USA))

    1990-01-01

    The enkephalin analog (2-D-penicillamine, 5-D-penicillamine)enkephalin was radioiodinated (125I-DPDPE) and shown to retain a pharmacological selectivity characteristic of the delta opioid receptor in in vitro binding studies. The distributions of 125I-DPDPE binding, using in vitro autoradiographic techniques, were similar to those previously reported for the delta opioid receptor. The nucleus accumbens, striatum, and medial prefrontal cortex contain dense gradients of 125I-DPDPE binding in regions known to receive dopaminergic afferents emanating from the mesencephalic tegmentum. Selective chemical lesions of the ventral tegmental area and substantia nigra were employed to deduce the location of the 125I-DPDPE binding within particular regions of the mesocorticolimbic dopamine system. Unilateral lesions of dopamine perikarya (A9 and A10) within the ventral tegmental area and substantia nigra produced by mesencephalic injection of 6-hydroxydopamine resulted in significant (20-30%) increases in 125I-DPDPE binding contralateral to the lesion within the striatum and nucleus accumbens. Lesions of the perikarya (dopaminergic and nondopaminergic) of the ventral tegmental area, induced by quinolinic acid injections, caused increases of less magnitude within these same nuclei. No significant alterations in 125I-DPDPE binding were observed within the mesencephalon as a result of either treatment. The specificity of the lesions was confirmed by immunocytochemistry for tyrosine hydroxylase. These results suggest that the enkephalins and opioid agonists acting through delta opioid receptors do not directly modulate dopaminergic afferents but do regulate postsynaptic targets of the mesocorticolimbic dopamine system.

  16. Depositional System Transition from Braided River to Tide Dominated Delta-A Case Study of the MPE3 Block in the Eastern Venezuelan Basin

    Science.gov (United States)

    Huang, Wensong; Chen, Heping; Xu, Fang; Meng, Zheng; Li, Yonghao

    2017-04-01

    The Eastern Venezuelan basin is a world-class petroliferous area, with the sedimentary environment controlled by the interaction between the Caribbean plate and the American plate. Based on interpretation of 3D seismic data, description of electrical well-logging facies and analysis of the sedimentary phenomena on the cores, we distinguished different types of sedimentary associations and clarified the evolution progress of the sedimentary system in the study area, the MPE3 Block. We put forward that depositional system in the study area changed from braided river in the early Miocene to tide dominated delta in the middle Miocene. Paralleled with sedimentary progress, the depositional hydrodynamic mechanism altered from the inertia dominated setting into the buoyancy dominated setting. During the middle Miocene, the tidal effect obviously reworked and formed tidal bars and tidal channels, both severing as the sedimentary framework. From the perspective of the tectonic movement, the study area varied from the foreland stage during the early Miocene to the compression and inverse stage during the middle Miocene. At the same time, the study area located in the southern part of the foreland basin began to extend and marine transgression occurred due to the tectonic extensional movement. We pointed out that critical factors influencing the transition from braided river to tidal dominate delta include palaeogeomorphology, sea level fluctuation, feeder system and the distance to catchment area.

  17. Earthquake imprints on a lacustrine deltaic system: The Kürk Delta along the East Anatolian Fault (Turkey)

    KAUST Repository

    Hubert-Ferrari, Aurélia

    2017-01-05

    Deltas contain sedimentary records that are not only indicative of water-level changes, but also particularly sensitive to earthquake shaking typically resulting in soft-sediment-deformation structures. The Kürk lacustrine delta lies at the south-western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re-evaluates water-level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic-reflection profiles and side-scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water-level changes provides a temporal framework for the depositional record. In addition to the common soft-sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake-induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (Cs and Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X-ray imagery, X-ray diffraction, loss-on-ignition, grain-size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post-seismic sediment reworking of earthquake-triggered landslides.

  18. Geomorphology of the Chippewa River delta of Glacial Lake Saginaw, central Lower Michigan, USA

    Science.gov (United States)

    Connallon, Christopher B.; Schaetzl, Randall J.

    2017-08-01

    and prograded as lake levels in the Saginaw Lowlands alternated and episodically fell. The result is a delta that is comparatively thin, expansive, and sandy. In some places, these sands have subsequently been reworked into fields of small parabolic dunes.

  19. U-Pb isotopic systematics of zircons from prograde and retrograde transition zones in high-grade orthogneisses, Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Baur, N.; Liew, T.C.; Todt, W.; Hofmann, A.W. (Max-Planck-Institut fuer Chemie, Mainz (West Germany)); Kroener, A. (Univ. Mainz (West Germany)); Williams, I.S. (Australian National Univ., Canberra (Australia))

    1991-07-01

    The authors present U-Pb zircon isotopic data from locally restricted prograde (arrested in situ charnockitization) and retrograde metamorphic transition zones, which are well exposed in Proterozoic orthogneisses tectonically interbanded with granulite facies supracrustal rocks of the Highland Group in Sri Lanka. These granitoid rocks yield apparent ages of 1942 {plus minus} 22 Ma, {approximately} 770 Ma, {approximately} 660 Ma, and {approximately} 560 Ma. All samples show severe Pb-loss some 550-560 Ma ago. The main phase of granulite-formation could not be dated unambiguously but is bracketed between {approximately} 660 Ma and {approximately} 550 Ma. The pervasive Pb-loss event around 550-560 Ma reflects the end of this period of high-grade metamorphism and was associated with widespread igneous activity and retrogression. This is constrained by the 550 {plus minus} 3 Ma intrusion age for a post-tectonic granite. They relate this late phase of thermal activity to crustal uplift of the Sri Lankan granulites. This data unambiguously prove the high-grade history of the Sri Lanka gneisses to be a late Precambrian event that may be related to the Pan-African evolution along the eastern part of Africa.

  20. Mitigation of negative ecological and socio-economic impacts of the Diama dam on the Senegal River Delta wetland (Mauritania, using a model based decision support system

    Directory of Open Access Journals (Sweden)

    S. Duvail

    2003-01-01

    Full Text Available Abstract: The delta of the River Senegal was modified substantially by the construction of the Diama dam in 1986 and the floodplain and estuarine areas on the Mauritanian bank were affected severely by the absence of floods. In 1994, managed flood releases were initiated in the Bell basin (4000 ha of the Diawling National Park, as part of a rehabilitation effort. The basin was designated as a joint management area between traditional users and the Park authority and a revised management plan was developed through a participatory approach based on a topographical, hydro-climatic, ecological and socio-economic data. Hydraulic modelling was developed as a tool to support stakeholder negotiations on the desired characteristics of the managed flood releases. Initially, a water balance model was developed. The data were then integrated into a one-dimensional hydraulic model, MIKE 11 (DHI, 2000. When associated with a Digital Elevation Model and a Geographic Information System, (Arc View, the model provided a dynamic description of floods. Flood extent, water depth and flood duration data were combined with ecological and socio-economic data. The water requirements of the different stakeholders were converted to flood scenarios and the benefits and constraints analysed. A consensus scenario was reached through a participatory process. The volume of flood release required to restore the delta does not affect hydro-power generation, navigation or intensive irrigation, for which the dams in the basin were constructed. Hydraulic modelling provided useful inputs to stakeholder discussions and allows investigation of untested flood scenarios. Keywords: wetland restoration, water use conflicts, equity, Senegal River delta, Mauritania, Diawling National Park

  1. Cohesive Sedimentary Processes on River-Dominated Deltas: New Perspectives from the Mississippi River Delta Front, Gulf of Mexico

    Science.gov (United States)

    Bentley, S. J.; Keller, G. P.; Obelcz, J.; Maloney, J. M.; Xu, K.; Georgiou, I. Y.; Miner, M. D.

    2016-12-01

    On river deltas dominated by proximal sediment accumulation (Mississippi, Huang He, others), the delta front region is commonly dominated by rapid accumulation of cohesive fluvial sediments, and mass-wasting processes that remobilize recently deposited sediments. Mass transport is preconditioned in sediments by high water content, biogenic gas production, over steepening, and is commonly triggered by strong wave loading and other processes. This understanding is based on extensive field studies in the 1970's and 80's. Recent studies of the Mississippi River Delta Front are yielding new perspectives on these processes, in a time of anthropogenically reduced sediment loads, rising sea level, and catastrophic deltaic land loss. We have synthesized many industry data sets collected since ca. 1980, and conducted new pilot field and modeling studies of sedimentary and morphodynamic processes. These efforts have yielded several key findings that diverge from historical understanding of this dynamic setting. First, delta distributary mouths have ceased seaward progradation, ending patterns that have been documented since the 18th century. Second, despite reduced sediment supply, offshore mass transport continues, yielding vertical displacements at rates of 1 m/y. This displacement is apparently forced by wave loading from storm events of near-annual return period, rather than major hurricanes that have been the focus of most previous studies. Third, core analysis indicates that this vertical displacement is occurring along failure planes >3 m in the seabed, rather than in more recently deposited sediments closer to the sediment-water interface. These seabed morphodynamics have the potential to destabilize both nearshore navigation infrastructure, and seabed hydrocarbon infrastructure offshore. As well, these findings raise more questions regarding the future seabed evolution offshore of major river deltas, in response to anthropogenic and climatic forcing.

  2. Distortion-free delta-sigma beamforming.

    Science.gov (United States)

    Nilsen, Carl-Inge Colombo; Holm, Sverre

    2008-08-01

    We have analyzed a compact, digital delay- and-sum beamformer using 1-bit delta-sigma A/D converters, where dynamic delays are applied directly to the delta-sigma modulated bitstream. It has previously been shown that the introduction of this time-variant operation into the time-invariant delta-sigma demodulator distorts the output signal, and several methods for minimizing this effect have been suggested. We have described the effect using standard system terminology. Based on this description, a new method for removing the distortion without any significant increase in system complexity is introduced. Its advantages, performance-wise, are supported by theoretical assessments and simulations.

  3. The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene–Holocene sediments in the Mekong River Delta

    Directory of Open Access Journals (Sweden)

    Truong Minh Hoang

    2016-11-01

    Full Text Available The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene–Holocene deposits in the Mekong River delta (MRD, and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene–Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU. The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

  4. Astrobee Periodic Technical Review (PTR) Delta 3

    Science.gov (United States)

    Provencher, Christopher; Smith, Marion F.; Smith, Ernest Everett; Bualat, Maria Gabriele; Barlow, Jonathan Spencer

    2017-01-01

    Astrobee is a free flying robot for the inside of the International Space Station (ISS). The Periodic Technical Review (PTR) delta 3 is the final design review of the system presented to stakeholders.

  5. Squamish Sleuthing: Origin and behaviour of different types of up-slope migrating bedform trains on the Squamish Delta

    Science.gov (United States)

    Hizzett, Jamie L.; Cartigny, Matthieu J. B.; Hughes Clarke, John E.; Talling, Peter J.; Clare, Michael A.

    2015-04-01

    Turbidity currents are important because they can undermine seafloor structural foundations for oil and gas pipelines, break strategically important cable networks, and their deposits form commercially important oil and gas reservoir. An important advancement in our understanding of turbidity currents has been that supercritical flow conditions are common. It is known that upper regime flow and different bedform morphologies associated with such flows exist, but the mechanisms through which these flows and bedforms are produced are not yet fully understood. As shown by Hughes Clarke et al., (2013, 2013), Paull et al., (2010) and others, upstream migrating bedforms are ubiquitous in turbidititic systems, but linking flow to process remains somewhat elusive. The link between flow and process is crucial in outcrop investigations determining the origins of different flow types based on their spatial range and bed morphologies. Numerical models will also benefit from this link as flow parameters form the basis of numerical models. Advances in technology have improved direct monitoring of the dynamics of turbidity currents, their interaction with the beds, and links between flows and deposits. As a result of the advent and refinement of acoustic technologies, high resolution bathymetric images and real-time flow data can now be collected. Here we present the analysis of repeat high resolution bathymetric data showing trains of upslope migrating bedforms on the Squamish Delta. The analysis shows that many of the bedform trains extend upslope to distinct failure scars near the delta-lip, but many other bedforms trains start far from the delta lip in mid-slope. As noted by Hughes Clarke et al. (2014) some of the mid-slope bedforms are not associated with a measureable failure scar. This suggests that not all of the bedforms are triggered by failure of the locally steep (40 degree) prograding mouth bar, or by plunging river discharge at the delta lip. The distances to which

  6. Delta hedging strategies comparison

    DEFF Research Database (Denmark)

    De Giovanni, Domenico; Ortobelli, S.; Rachev, S.T.

    2008-01-01

    In this paper we implement dynamic delta hedging strategies based on several option pricing models. We analyze different subordinated option pricing models and we examine delta hedging costs using ex-post daily prices of S&P 500. Furthermore, we compare the performance of each subordinated model...

  7. Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India

    Directory of Open Access Journals (Sweden)

    Tim E. Johnson

    2015-05-01

    Full Text Available Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure–temperature–time (P–T–t evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagioclase, magnetite, ilmenite, spinel and melt is consistent with peak metamorphic pressures of 6–8 kbar and temperatures in excess of 900 °C. Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 °C. SHRIMP U–Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages. New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation, and the minimum age of the metamorphic peak, to around 560 Ma. The data suggest two stages of monazite growth. The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite. Relatively REE-depleted rims, which have a pronounced negative europium anomaly, grew during melt crystallisation along the retrograde path at around 535 Ma. Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer, supporting a long-lived high-grade metamorphic history. The metamorphic conditions, timing and duration of the implied clockwise P–T–t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent.

  8. Environmental comparison of intensive and integrated agriculture-aquaculture systems for striped catfish production in the Mekong Delta, Vietnam, based on two existing case studies using life cycle assessment

    NARCIS (Netherlands)

    Kluts, I.N.; Potting, J.M.B.; Bosma, R.H.; Phong, L.T.; Udo, H.M.J.

    2012-01-01

    Vietnam is the largest producer for the export of striped catfish. Traditionally striped catfish production in the Mekong Delta took place in integrated agriculture–aquaculture systems, but has shifted recently to intensive systems to meet increasing export demands. A recent study quantified the

  9. Development of a Web-based GIS monitoring and environmental assessment system for the Black Sea: application in the Danube Delta area.

    Science.gov (United States)

    Tziavos, Ilias N; Alexandridis, Thomas K; Aleksandrov, Borys; Andrianopoulos, Agamemnon; Doukas, Ioannis D; Grigoras, Ion; Grigoriadis, Vassilios N; Papadopoulou, Ioanna D; Savvaidis, Paraskevas; Stergioudis, Argyrios; Teodorof, Liliana; Vergos, Georgios S; Vorobyova, Lyudmila; Zalidis, Georgios C

    2016-08-01

    In this paper, the development of a Web-based GIS system for the monitoring and assessment of the Black Sea is presented. The integrated multilevel system is based on the combination of terrestrial and satellite Earth observation data through the technological assets provided by innovative information tools and facilities. The key component of the system is a unified, easy to update geodatabase including a wide range of appropriately selected environmental parameters. The collection procedure of current and historical data along with the methods employed for their processing in three test areas of the current study are extensively discussed, and special attention is given to the overall design and structure of the developed geodatabase. Furthermore, the information system includes a decision support component (DSC) which allows assessment and effective management of a wide range of heterogeneous data and environmental parameters within an appropriately designed and well-tested methodology. The DSC provides simplified and straightforward results based on a classification procedure, thus contributing to a monitoring system not only for experts but for auxiliary staff as well. The examples of the system's functionality that are presented highlight its usability as well as the assistance that is provided to the decision maker. The given examples emphasize on the Danube Delta area; however, the information layers of the integrated system can be expanded in the future to cover other regions, thus contributing to the development of an environmental monitoring system for the entire Black Sea.

  10. Artificial delta growth

    Science.gov (United States)

    Mikeš, Daniel

    2010-05-01

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

  11. Evolving deltas: Coevolution with engineered interventions

    Directory of Open Access Journals (Sweden)

    A. C. Welch

    2017-08-01

    Full Text Available Deltaic environments are often densely populated with high socio-economic values, and thus are hotspots of climatic, environmental and anthropogenic change. Large scale engineered structures, such as dike systems, have played an important role in shaping both environmental and socio-economic conditions in deltas, with such interventions more likely where there is a high population and a wealthy economy. Engineered interventions interact with the morphological evolution of the delta, reducing or removing sedimentation and accelerating subsidence, increasing the consequences of flooding and necessitating further adaptation. They also encourage further development, reinforcing this feedback. Thus, in these cases, the deltaic landscape and associated livelihoods can be considered to be the result of a coevolution process between natural delta processes and human engineered interventions. This paper explores this hypothesis. It analyses the history of large scale engineering interventions and their implications in five representative, large, populated deltas across the globe (Ganges-Brahmaputra-Meghna, Yangtze, Rhine-Meuse-Scheldt, Mekong and Nile. The results demonstrate coevolution has occurred and indicate that the response type and the management approach of these engineered structures have significant implications for future delta development. To understand and manage unintended consequences and the development of lock-in trajectories in deltas, a systematic understanding of delta development, including these coevolution processes is essential.

  12. Systemic expression of Notch ligand Delta-like 4 during mycobacterial infection alters the T cell immune response

    Directory of Open Access Journals (Sweden)

    Matthew Schaller

    2016-11-01

    Full Text Available The Notch ligand Delta-like 4 (DLL4 is known to fine-tune the CD4+ T cell cytokine response. DLL4 is expressed on the surface of antigen presenting cells in a MyD88 dependent manner. We found that DLL4 expression was upregulated on bone marrow progenitor cells and antigen presenting cells in mice infected with BCG mycobacterium. Transfer of DLL4+ progenitor cells from infected hosts resulted in an increase DLL4+ myeloid cells in the spleen, indicating that expression of the dll4 gene is propagated throughout hematopoiesis. We also found an increase in DLL4+ monocytes from individuals that were infected with M. tuberculosis. In latent individuals, DLL4 expression correlated with increased cytokine production from T cells in response to PPD stimulation. Finally, antibody blockade of DLL4 reduced T cell cytokine production from naïve T cells stimulated with antigen. These results demonstrate that the Notch ligand DLL4 can influence T cell cytokine production in both humans and mice, and further reveal that expression of DLL4 is upregulated on early hematopoietic progenitors in response to chronic mycobacterial infection. These data suggest that widespread DLL4 expression may occur as a result of mycobacterial infection, and that this expression may alter CD4+ T cell responses to both previously encountered and novel antigens.

  13. Bottom morphology in the Song Hau distributary channel, Mekong River Delta, Vietnam

    Science.gov (United States)

    Allison, Mead A.; Dallon Weathers, H.; Meselhe, Ehab A.

    2017-09-01

    Field studies in the Song Hau distributary of the Mekong Delta in Vietnam conducted at high (Sept.-Oct 2014) and low (March 2015) Mekong River discharge are utilized to examine channel bottom morphology and links with sediment transport in the system. Multibeam bathymetric mapping surveys over the entire channel complex in the lower 80 km of the distributary channel, and over 12- to 24-h tidal periods at six transect locations in the reach are used to characterize bottom type and change on seasonal and tidal timescales, supplemented by bottom sampling. The results of this study indicate that the largest proportion of channel floor (up to 80% of the total area) is composed of substratum outcrops of relict sediment units deposited during the progradation of the delta in the last 3.5 ka. These take the form of outcrops that are either (1) steep-sided, tabular channel floor, (2) steep-sided sidewall, or (3) relatively flat channel floor. Flatter outcrops of channel floor substratum are identified by the presence of sedimentary furrows (<0.5 m deep) incised into the channel bottom that are exposed at high discharge and oriented along channel and laterally continuous for kilometers. These furrows are persistent in location and extent across tidal cycles and appear to be incised into relict units, sometimes with a thin surficial layer of modern sediment observable in bottom grabs. The extent of substratum exposure, greater than that observed previously in low tidal energy systems like the Mississippi River, may relate both to a relatively low sand supply from the catchment, and/or to an efficient transfer of both sand and mud through this tidally energetic channel. Sand bottom areas forming dunes, comprise about 19% of the channel floor over the study area and are generally less than a few meters thick except on bar extensions of mid-channel islands. Both sandy and substratum areas are mantled by soft muds 0.25-1 m thick during low discharge in the estuarine section of

  14. Effect of DC current polarization on the electrochemical behaviour of La{sub 2}NiO{sub 4+{delta}} and La{sub 3}Ni{sub 2}O{sub 7+{delta}}-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Coll, D.; Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/ Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-07-01

    The electrode performance of La{sub 2}NiO{sub 4} and La{sub 3}Ni{sub 2}O{sub 7} as cathode materials for solid oxide fuel cells (SOFC) was analyzed. The study was focused on the electrode polarization resistance of the interfaces formed by the cathodes with Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} + 2%Co electrolyte. The study was extended to cathodes based on La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite and Pt to analyze the effect of changing the electronic and/or ionic transport properties on the electrode interface resistance. The electrode performance was studied in open circuit conditions and with DC current polarization. Important differences in the performance of the pure cathode materials were obtained as function of DC current flux. However, in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite the DC current flux produces minor changes in the electrode polarization resistance. The aging process also affects the OCV electrode performance of cathodes based on Pt and pure ceramics, whereas the effect is practically invaluable in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite. The electrode performance is higher for the composite cathode compared to pure ceramic electrodes for OCV or for low values of DC polarization. However, the important decrease in the interface resistance obtained for high values of DC current flux for La{sub 2}NiO{sub 4} and La{sub 3}Ni{sub 2}O{sub 7} cathodes increases their electrode performances to values close to those obtained in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite. This retains the cathode overpotential with values as low as 140 mV at 750 C for values of current load of 530 mA cm{sup -2} for both pure and composite La{sub 2}NiO{sub 4}-based cathodes. The low cathode overpotential allows to estimate values of power density between 300 and 350 mW cm{sup -2} at 750 C for La{sub 2}NiO{sub 4}, La{sub 3}Ni{sub 2}O{sub 7} and La{sub 2}Ni

  15. Timing, duration and inversion of prograde Barrovian metamorphism constrained by high resolution Lu-Hf garnet dating: A case study from the Sikkim Himalaya, NE India

    Science.gov (United States)

    Anczkiewicz, Robert; Chakraborty, Sumit; Dasgupta, Somnath; Mukhopadhyay, Dilip; Kołtonik, Katarzyna

    2014-12-01

    We investigated Lu-Hf isotopic systematics in garnets from gradually higher grade metamorphic rocks from the first appearance of garnet at c. 500 °C to biotite dehydration melting at c. 800 °C in the Sikkim Himalaya, India. Exceptionally precise Lu-Hf ages obtained for the Barrovian metasedimentary sequence in the Lesser Himalaya (LH) correspond to the time of early garnet formation on a prograde path and show remarkable correlation with increasing metamorphic grade and decreasing structural depth. The youngest age is reported for the garnet zone (10.6±0.2 Ma) and then the ages become progressively older in the staurolite (12.8±0.3 Ma), kyanite (13.7±0.2 Ma) and sillimanite (14.6±0.1 Ma) zones. The oldest age of 16.8±0.1 Ma was recorded at the top of the sequence in the zone marking the onset of muscovite dehydration melting, directly below the Main Central Thrust (MCT). These ages provide a tight constraint on the timing and duration of the Barrovian sequence formation which lasted about 6 Ma. The age pattern is clearly inverted with respect to structural depth but shows "normal" correlation with the metamorphic grade, i.e. earlier garnet growth in higher grade rocks. The timing of the peak metamorphic conditions estimated for the garnet and kyanite zones suggests that thermal climax occurred in all zones within a relatively short time span about 10-13 Ma ago. The metamorphic inversion in the Sikkim Himalaya must therefore have occurred after the metamorphic peak was attained in all grades. Lu-Hf garnet ages in the overthrust Higher Himalaya (HH) continue to be older but do not show a clear progression. There is about 6 Ma jump to 22.6±0.1 Ma within the MCT zone and even older ages of 26-28 Ma were obtained for migmatites from the lower part of the HH. The Lu-Hf system in garnets from the HH records the time of melting at or near the thermal peak rather than dates initial garnet growth as in the LH. The age pattern obtained in this study provides precise

  16. Delta-robotin mekaniikkasuunnittelu

    OpenAIRE

    Välimäki, Pasi

    2015-01-01

    Tämän opinnäytetyön tarkoituksena oli suunnitella mekaniikka Delta-robotille, jonka on tarkoitus tulla opetuskäyttöön Seinäjoen ammattikorkeakoululle. Opinnäytetyöhön kuului selvittää, mitä Delta-robotin valmistaminen opetuskäyttöön vaatisi sekä laskea kinematiikka Delta-robotin raajojen ja ala-alustan liikkeille. Lisäksi opinnäytetyössä oli tarkoitus selvittää, mistä materiaalista Delta-robotti olisi kannattavinta valmistaa. Opinnäytetyöhön ei kuitenkaan kuulunut varsinaisen robotin valmista...

  17. Delta agent (Hepatitis D)

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000216.htm Hepatitis D (Delta agent) To use the sharing features on this page, please enable JavaScript. Hepatitis D is a viral infection caused by the ...

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

    Science.gov (United States)

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

    2016-04-01

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

  19. Prograde high- to ultrahigh-pressure metamorphism and exhumation of oceanic sediments at Lago di Cignana, Zermatt-Saas Zone, western Alps

    Science.gov (United States)

    Reinecke, T.

    1998-03-01

    Pelagic metasediments and MORB-type metabasalts of the former Tethyan oceanic crust at Cignana, Valtournanche, Italy, experienced UHP metamorphism and subsequent exhumation during the Early to Late Tertiary. Maximum PT conditions attained during UHP metamorphism were 600-630 °C, 2.7-2.9 GPa, which resulted in the formation of coesite-glaucophane-eclogites in the basaltic layer and of garnet-dolomite-aragonite-lawsonite-coesite-phengite-bearing calc-schists and garnet-phengite-coesite-schists with variable amounts of epidote, talc, dolomite, Na-pyroxene and Na-amphibole in the overlying metasediments. During subduction the rocks followed a prograde HP/UHP path which in correspondance with the Jurassic age of the Tethyan crust reflects the thermal influence of relatively old and cold lithosphere and of low to moderate shear heating. Inflections on the prograde metamorphic path may correspond to thermal effects that arise from a decrease in shear heating due to brittle-plastic transition in the quartz-aragonite-dominated rocks, induced convection in the asthenospheric mantle wedge and/or heat consumption by endothermic reactions over a restricted PT segment during subduction. After detachment from the downgoing slab some 50-70 Ma before present, the Cignana crustal slice was first exhumed to ca. 60 km and concomitantly cooled to ca. 550 °C, tracing back the UHP/HP prograde path displaced by 50-80 °C to higher temperatures. Exhumation at this stage is likely to have occurred in the Benioff zone, while the subduction of cool lithosphere was going on. Subsequently, the rocks were near-isothermally exhumed to ca. 30 km, followed by concomitant decompression and cooling to surface conditions (at glaucophane eclogites, the HP/UHP assemblages of the metasediments have been largely obliterated during exhumation. Relics from which the metamorphic evolution of the rocks during prograde HP metamorphism and the UHP stage can be retrieved are restricted to rigid low

  20. Delta-t protocol specification: working draft

    Energy Technology Data Exchange (ETDEWEB)

    Watson, R.W.

    1981-12-04

    This document is one of a series describing protocols associated with the Livermore Interactive Network Communication System (LINCS) hierarchical architecture. At the heart of LINCS is its basic interprocess communication (LINCS-IPC) service. LINCS-IPC defines a reliable, flow controlled, full duplex, uninterpreted, labeled bit stream communication service. LINCS-IPC is level 4 in the LINCS architecture. Level 3 of LINCS is the Network layer defining an internetwork datagram type service. LINCS-IPC interfaces to User processes that utilize higher level syntactic and semantic conventions for process interaction. The transport service provided by the Delta-t protocol can be considered a sublayer of the LINCS-IPC layer. Delta-t augments the Network level service as required to support LINCS-IPC. This document specifies the services provided by the Delta-t protocol to support LINCS-IPC, the operation of Delta-t, and the services Delta-t requires of the Network level. This document was written to be self-contained but the reader will find it useful to have available for reference the LINCS-IPC and LINCS DeltaGram Network layer protocol specifications. Implementations are underway in Pascal for the PDP-11 running under RT11 and RX11, in BLISS for the VAX running under VMS, in MODEL for the CRAY-1 and CDC 7600 running under NLTSS and LTSS, and for the SEL 32/75 running under PORT.

  1. SU-E-T-115: Analysis of Patient Specific QA for VMAT by Disease Site and Planning-Delivery System Using the ScandiDos Delta4 Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Giaddui, T; Hardin, M; Keller, J; Kremmel, E; Peng, C; Doyle, L; Yu, Y; Xiao, Y; Harrison, A [Thomas Jefferson University, Philadelphia, PA (United States); Fu, M [Juniata College, Huntingdon, PA (United States)

    2015-06-15

    Purpose: To evaluate patient specific quality assurance (PSQA) for the delivery of volumetric modulated arc therapy (VMAT) by disease site. To compare planning-delivery system (PDS) PSQA pass rates in a dual vendor institution. Methods: PSQA is performed for VMAT plans using a ScandiDos Delta4 phantom. Verification plans are calculated using Varian Eclipse and Elekta Monaco treatment planning systems (TPS) for patients treated using Varian Truebeam and Elekta linear accelerators respectively. Individual arcs are delivered to the Delta4 phantoms and assessed using the gamma index pass criterion(3% Dose Deviation(DD%), 3mm Distance to Agreement(DTA),10% dose threshold and 90% gamma index). Results: A total of 287 VMAT plans and 680 arcs were analyzed. The passing rates for VMAT QA plans were 95% and 98% for head/neck and pelvis/prostate plans respectively, and 100% for chest/abdomen, spine, lung Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery(SRS) plans. Average gamma indices were: (99 ± 2) % for pelvis/prostate, chest/abdomen and lung SBRT plans, (97 ± 4) % for head and neck plans and (98 ± 3) % for spine plans. The average DD% and DTA pass rates ranged from 82% to 90% and 98% to 99% respectively for plans in different disease sites. Paired t-test analysis (two tails) indicated no significant differences in the gamma indices between plans delivered using different PDS; the P values were: 0.08, 0.45, and 0.94 for lung SBRT, head/neck and pelvis/prostate plans respectively. The statistical power for comparing PDS in different disease sites with an alpha of 0.05 is 1. Conclusion: The Gamma indices based on 3% DD%, 3 mm DTA and 10% dose threshold for the VMAT QA plans in all disease sites were well above 90%, suggesting the possibility of using a more stringent PSQA criterion. No significant differences were observed in the QA of VMAT plans delivered using different PDS.

  2. {\\delta}M Formalism

    CERN Document Server

    Talebian-Ashkezari, Alireza; Abolhasani, Ali Akbar

    2016-01-01

    We study the evolution of the "non-perturbative" metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the "{\\delta}M formalism" for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so-called {\\delta}N formula for the super-horizon dynamics of the curvature perturbations. Likewise its ancestor, {\\delta}N formalism, this new method can substantially reduce the amount of calculations related to the evolution of the tensor modes.

  3. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, REMOVAL OF ARSENIC IN DRINKING WATER: DELTA INDUSTRIAL SERVICES, INC., CAMPWATER PORTA-5 SYSTEM

    Science.gov (United States)

    The CampWater system uses ozonation followed by cartridge filtration to remove arsenic via co-precipitation. The system utilizes ozone to oxidize iron and arsenic (III) to arsenic (V). The arsenic bound to the iron precipitates is then removed by cartridge filtration. No additi...

  4. Digital radio-over-fiber system with multi-pulse Manchester encoding-assisted delta-sigma modulation.

    Science.gov (United States)

    Jang, Seunghyun; Park, Bonghyuk; Hong, Songcheol

    2017-04-03

    Two ∆Σ-modulated digital radio-over-fiber (DRoF) transmission systems that employ a multi-pulse Manchester encoder are proposed and experimentally evaluated. With a two-step modulation process comprised of ∆Σ modulation and multi-pulse Manchester encoding, a high frequency replica or image of a ∆Σ-digitized analog communication signal can be transmitted without significant power loss. This is achieved by exploiting the spectral characteristics of the modified Manchester code. For comparative analysis, a conventional ∆Σ-modulation-based DRoF system is also evaluated. Based on the evaluation results, the proposed DRoF systems more significantly improve the reliability and flexibility of the RoF system by providing higher power margins or by making the DRoF system implementation more cost-effective and easier to perform on account of the low-frequency requirement for electronics and optical transceivers.

  5. A ground penetrating radar investigation of a glacial-marine ice- contact delta, Pineo Ridge, eastern coastal Maine

    Science.gov (United States)

    Tary, A.K.; Duncan, M. FitzGerald; Weddle, T.K.

    2007-01-01

    In eastern coastal Maine, many flat-topped landforms, often identified as glacial-marine deltas, are cultivated for blueberry production. These agriculturally valuable features are not exploited for aggregate resources, severely limiting stratigraphic exposure. Coring is often forbidden; where permissible, coarse-grained surficial sediments make coring and sediment retrieval difficult. Ground penetrating radar (GPR) has become an invaluable tool in an ongoing study of the otherwise inaccessible subsurface morphology in this region and provides a means of detailing the large-scale sedimentary structures comprising these features. GPR studies allow us to reassess previous depositional interpretations and to develop alternative developmental models. The work presented here focuses on Pineo Ridge, a large, flat-topped ice-marginal glacial-marine delta complex with a strong linear trend and two distinct landform zones, informally termed East Pineo and West Pineo. Previous workers have described each zone separately due to local morphological variation. Our GPR work further substantiates this geomorphic differentiation. East Pineo developed as a series of deltaic lobes prograding southward from an ice-contact margin during the local marine highstand. GPR data do not suggest postdepositional modification by ice-margin re-advance. We suggest that West Pineo has a more complex, two-stage depositional history. The southern section of the feature consists of southward-prograding deltaic lobes deposited during retreat of the Laurentide ice margin, with later erosional modification during marine regression. The northern section of West Pineo formed as a series of northward-prograd- ing deltaic lobes as sediment-laden meltwater may have been diverted by the existing deposits of the southern section of West Pineo. ?? 2007 The Geological Society of America. All rights reserved.

  6. The benefits of multibit chaotic sigma delta modulation.

    Science.gov (United States)

    Reiss, J. D.; Sandler, M. B.

    2001-06-01

    Sigma delta modulation is a popular technique for high-resolution analog-to-digital conversion and digital-to-analog conversion. We investigate chaotic phenomena in multibit first-order sigma-delta modulators. Particular attention is placed on the occurrence of periodic orbits or limit cycles. These may result in idle tones audible to the listener when sigma-delta modulation is used for audio signal processing. One suggested method of eliminating idle tones is the operation of a sigma delta modulator in the chaotic regime. Unfortunately, chaotic modulation of a first order sigma delta modulator is a poor system for signal processing. We show that minor variations on a traditional first order sigma-delta modulator, together with a multibit implementation, may be used to produce an effective, stable chaotic modulator that accurately encodes the input and helps remove the presence of idle tones. (c) 2001 American Institute of Physics.

  7. Assessing a cross-border logistics policy using a performance measurement system framework: the case of Hong Kong and the Pearl River Delta region

    Science.gov (United States)

    Wong, David W. C.; Choy, K. L.; Chow, Harry K. H.; Lin, Canhong

    2014-06-01

    For the most rapidly growing economic entity in the world, China, a new logistics operation called the indirect cross-border supply chain model has recently emerged. The primary idea of this model is to reduce logistics costs by storing goods at a bonded warehouse with low storage cost in certain Chinese regions, such as the Pearl River Delta (PRD). This research proposes a performance measurement system (PMS) framework to assess the direct and indirect cross-border supply chain models. The PMS covers four categories including cost, time, quality and flexibility in the assessment of the performance of direct and indirect models. Furthermore, a survey was conducted to investigate the logistics performance of third party logistics (3PLs) at the PRD regions, including Guangzhou, Shenzhen and Hong Kong. The significance of the proposed PMS framework allows 3PLs accurately pinpoint the weakness and strengths of it current operations policy at four major performance measurement categories. Hence, this helps 3PLs further enhance the competitiveness and operations efficiency through better resources allocation at the area of warehousing and transportation.

  8. The Niger Delta Crisis

    African Journals Online (AJOL)

    chifaou.amzat

    2013-09-28

    Sep 28, 2013 ... Council for the Development of Social Science Research in Africa, 2013. (ISSN 0850–7902). *. Department of History & International Studies, Delta State ..... and rocket propelled grenade launchers to carry out precise attack on installations in the region. The initial thinking that the military would rout.

  9. onshore, niger delta

    African Journals Online (AJOL)

    User

    2016-12-02

    Dec 2, 2016 ... ABSTRACT. Three wells A1, A2 and A3 were identified on the 'T-X' field in onshore Niger Delta. A comprehensive petrophysical analysis on one of the wells (well A1) was carried out in order to come up with physical properties such as shale volume, porosity (Φ), permeability (K), fluid saturation, and net ...

  10. The Niger Delta

    African Journals Online (AJOL)

    AJL

    2009-05-26

    May 26, 2009 ... For nearly three decades, conflicts surrounding environmental degradation, human security, and international development have dominated news about the ... Permanent night light sources as documented by United States Air Force Defense Meteorological Program shows flaring trouble in the Niger Delta ...

  11. The Niger Delta, Crisis

    African Journals Online (AJOL)

    sulaiman.adebowale

    2007-09-10

    Sep 10, 2007 ... actions of the oil multinational corporations, with severe implications for Nige- ..... practice of supporting divisions of the Nigerian armed forces with opera- .... creeks) and fish, forest and human resources, the Niger Delta also supports ..... greatly undermined the global influence of Nigeria as Africa's most ...

  12. western niger delta, nigeria

    African Journals Online (AJOL)

    HP

    2015-07-21

    Jul 21, 2015 ... Ditch cutting samples from well 'Y' retrieved from the Niger Delta Basin were made available by. Chevron Nigeria Ltd for this study. The sampling .... temperatures as indicated with the increase in the quantities of Monoporites annulatus. Vermoere et al. (1999) in a study in SW Turkey reported that high.

  13. onshore, niger delta

    African Journals Online (AJOL)

    User

    2016-12-02

    Dec 2, 2016 ... clays were transported to deep water areas characterized by low energy conditions and oxygen deficiency (Stacher, 1995). The formation underlies the entire delta, and is typically over pressured. The approximate range of the thickness is about 6,000m. (Paul, 2003).Deposition of the overlying Agbada.

  14. The Niger Delta

    African Journals Online (AJOL)

    AJL

    2009-05-26

    May 26, 2009 ... slave mart in West Africa. In the first thirty years of the nineteenth century when the trade in palm oil had begun to displace the ... shows flaring trouble in the Niger Delta region. Data from 1995 are represented in blue, 2000 in green and 2006 in red. The gas flares associated with petroleum industry are ...

  15. Climate Change and the Delta

    Directory of Open Access Journals (Sweden)

    Michael Dettinger

    2016-10-01

    Full Text Available doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art5Anthropogenic climate change amounts to a rapidly approaching, “new” stressor in the Sacramento–San Joaquin Delta system. In response to California’s extreme natural hydroclimatic variability, complex water-management systems have been developed, even as the Delta’s natural ecosystems have been largely devastated. Climate change is projected to challenge these management and ecological systems in different ways that are characterized by different levels of uncertainty. For example, there is high certainty that climate will warm by about 2°C more (than late-20th-century averages by mid-century and about 4°C by end of century, if greenhouse-gas emissions continue their current rates of acceleration. Future precipitation changes are much less certain, with as many climate models projecting wetter conditions as drier. However, the same projections agree that precipitation will be more intense when storms do arrive, even as more dry days will separate storms. Warmer temperatures will likely enhance evaporative demands and raise water temperatures. Consequently, climate change is projected to yield both more extreme flood risks and greater drought risks. Sea level rise (SLR during the 20th century was about 22 cm, and is projected to increase by at least 3-fold this century. SLR together with land subsidence threatens the Delta with greater vulnerabilities to inundation and salinity intrusion. Effects on the Delta ecosystem that are traceable to warming include SLR, reduced snowpack, earlier snowmelt and larger storm-driven streamflows, warmer and longer summers, warmer summer water temperatures, and water-quality changes. These changes and their uncertainties will challenge the operations of water projects and uses throughout the Delta’s watershed and delivery areas. Although the effects of of climate change on Delta ecosystems may be profound, the end results are difficult to predict

  16. Climate change and the Delta

    Science.gov (United States)

    Dettinger, Michael; Anderson, Jamie; Anderson, Michael L.; Brown, Larry R.; Cayan, Daniel; Maurer, Edwin P.

    2016-01-01

    Anthropogenic climate change amounts to a rapidly approaching, “new” stressor in the Sacramento–San Joaquin Delta system. In response to California’s extreme natural hydroclimatic variability, complex water-management systems have been developed, even as the Delta’s natural ecosystems have been largely devastated. Climate change is projected to challenge these management and ecological systems in different ways that are characterized by different levels of uncertainty. For example, there is high certainty that climate will warm by about 2°C more (than late-20th-century averages) by mid-century and about 4°C by end of century, if greenhouse-gas emissions continue their current rates of acceleration. Future precipitation changes are much less certain, with as many climate models projecting wetter conditions as drier. However, the same projections agree that precipitation will be more intense when storms do arrive, even as more dry days will separate storms. Warmer temperatures will likely enhance evaporative demands and raise water temperatures. Consequently, climate change is projected to yield both more extreme flood risks and greater drought risks. Sea level rise (SLR) during the 20th century was about 22cm, and is projected to increase by at least 3-fold this century. SLR together with land subsidence threatens the Delta with greater vulnerabilities to inundation and salinity intrusion. Effects on the Delta ecosystem that are traceable to warming include SLR, reduced snowpack, earlier snowmelt and larger storm-driven streamflows, warmer and longer summers, warmer summer water temperatures, and water-quality changes. These changes and their uncertainties will challenge the operations of water projects and uses throughout the Delta’s watershed and delivery areas. Although the effects of climate change on Delta ecosystems may be profound, the end results are difficult to predict, except that native species will fare worse than invaders. Successful

  17. Integrated studies of a regional ozone pollution synthetically affected by subtropical high and typhoon system in the Yangtze River Delta region, China

    Directory of Open Access Journals (Sweden)

    L. Shu

    2016-12-01

    Full Text Available Severe high ozone (O3 episodes usually have close relations to synoptic systems. A regional continuous O3 pollution episode was detected over the Yangtze River Delta (YRD region in China during 7–12 August 2013, in which the O3 concentrations in more than half of the cities exceeded the national air quality standard. The maximum hourly concentration of O3 reached 167.1 ppb. By means of the observational analysis and the numerical simulation, the characteristics and the essential impact factors of the typical regional O3 pollution are comprehensively investigated. The observational analysis shows that the atmospheric subsidence dominated by the western Pacific subtropical high plays a crucial role in the formation of high-level O3. The favorable weather conditions, such as extremely high temperature, low relative humidity and weak wind speed, caused by the abnormally strong subtropical high are responsible for the trapping and the chemical production of O3 in the boundary layer. In addition, when the YRD cities are at the front of Typhoon Utor, the periphery circulation of typhoon system can enhance the downward airflows and cause worse air quality. However, when the typhoon system weakens the subtropical high, the prevailing southeasterly surface wind leads to the mitigation of the O3 pollution. The integrated process rate (IPR analysis incorporated in the Community Multi-scale Air Quality (CMAQ model is applied to further illustrate the combined influence of subtropical high and typhoon system in this O3 episode. The results show that the vertical diffusion (VDIF and the gas-phase chemistry (CHEM are two major contributors to O3 formation. During the episode, the contributions of VDIF and CHEM to O3 maintain the high values over the YRD region. On 10–12 August, the cities close to the sea are apparently affected by the typhoon system, with the contribution of VDIF increasing to 28.45 ppb h−1 in Shanghai and 19.76 ppb h−1 in

  18. An Integrated Hydrological and Water Management Study of the Entire Nile River System - Lake Victoria to Nile Delta

    Science.gov (United States)

    Habib, Shahid; Zaitchik, Benjamin; Alo, Clement; Ozdogan, Mutlu; Anderson, Martha; Policelli, Fritz

    2011-01-01

    The Nile basin River system spans 3 million km(exp 2) distributed over ten nations. The eight upstream riparian nations, Ethiopia, Eretria, Uganda, Rwanda, Burundi, Congo, Tanzania and Kenya are the source of approximately 86% of the water inputs to the Nile, while the two downstream riparian countries Sudan and Egypt, presently rely on the river's flow for most of the their needs. Both climate and agriculture contribute to the complicated nature of Nile River management: precipitation in the headwaters regions of Ethiopia and Lake Victoria is variable on a seasonal and inter-annual basis, while demand for irrigation water in the arid downstream region is consistently high. The Nile is, perhaps, one of the most difficult trans-boundary water issue in the world, and this study would be the first initiative to combine NASA satellite observations with the hydrologic models study the overall water balance in a to comprehensive manner. The cornerstone application of NASA's Earth Science Research Results under this project are the NASA Land Data Assimilation System (LDAS) and the USDA Atmosphere-land Exchange Inverse (ALEXI) model. These two complementary research results are methodologically independent methods for using NASA observations to support water resource analysis in data poor regions. Where an LDAS uses multiple sources of satellite data to inform prognostic simulations of hydrological process, ALEXI diagnoses evapotranspiration and water stress on the basis of thermal infrared satellite imagery. Specifically, this work integrates NASA Land Data Assimilation systems into the water management decision support systems that member countries of the Nile Basin Initiative (NBI) and Regional Center for Mapping of Resources for Development (RCMRD, located in Nairobi, Kenya) use in water resource analysis, agricultural planning, and acute drought response to support sustainable development of Nile Basin water resources. The project is motivated by the recognition that

  19. Projected evolution of California's San Francisco bay-delta-river system in a century of climate change

    Science.gov (United States)

    Cloern, J.E.; Knowles, N.; Brown, L.R.; Cayan, D.; Dettinger, M.D.; Morgan, T.L.; Schoellhamer, D.H.; Stacey, M.T.; van der Wegen, M.; Wagner, R.W.; Jassby, A.D.

    2011-01-01

    Background: Accumulating evidence shows that the planet is warming as a response to human emissions of greenhouse gases. Strategies of adaptation to climate change will require quantitative projections of how altered regional patterns of temperature, precipitation and sea level could cascade to provoke local impacts such as modified water supplies, increasing risks of coastal flooding, and growing challenges to sustainability of native species. Methodology/Principal Findings: We linked a series of models to investigate responses of California's San Francisco Estuary-Watershed (SFEW) system to two contrasting scenarios of climate change. Model outputs for scenarios of fast and moderate warming are presented as 2010-2099 projections of nine indicators of changing climate, hydrology and habitat quality. Trends of these indicators measure rates of: increasing air and water temperatures, salinity and sea level; decreasing precipitation, runoff, snowmelt contribution to runoff, and suspended sediment concentrations; and increasing frequency of extreme environmental conditions such as water temperatures and sea level beyond the ranges of historical observations. Conclusions/Significance: Most of these environmental indicators change substantially over the 21st century, and many would present challenges to natural and managed systems. Adaptations to these changes will require flexible planning to cope with growing risks to humans and the challenges of meeting demands for fresh water and sustaining native biota. Programs of ecosystem rehabilitation and biodiversity conservation in coastal landscapes will be most likely to meet their objectives if they are designed from considerations that include: (1) an integrated perspective that river-estuary systems are influenced by effects of climate change operating on both watersheds and oceans; (2) varying sensitivity among environmental indicators to the uncertainty of future climates; (3) inevitability of biological community

  20. Projected evolution of California's San Francisco Bay-Delta-river system in a century of climate change.

    Directory of Open Access Journals (Sweden)

    James E Cloern

    Full Text Available BACKGROUND: Accumulating evidence shows that the planet is warming as a response to human emissions of greenhouse gases. Strategies of adaptation to climate change will require quantitative projections of how altered regional patterns of temperature, precipitation and sea level could cascade to provoke local impacts such as modified water supplies, increasing risks of coastal flooding, and growing challenges to sustainability of native species. METHODOLOGY/PRINCIPAL FINDINGS: We linked a series of models to investigate responses of California's San Francisco Estuary-Watershed (SFEW system to two contrasting scenarios of climate change. Model outputs for scenarios of fast and moderate warming are presented as 2010-2099 projections of nine indicators of changing climate, hydrology and habitat quality. Trends of these indicators measure rates of: increasing air and water temperatures, salinity and sea level; decreasing precipitation, runoff, snowmelt contribution to runoff, and suspended sediment concentrations; and increasing frequency of extreme environmental conditions such as water temperatures and sea level beyond the ranges of historical observations. CONCLUSIONS/SIGNIFICANCE: Most of these environmental indicators change substantially over the 21(st century, and many would present challenges to natural and managed systems. Adaptations to these changes will require flexible planning to cope with growing risks to humans and the challenges of meeting demands for fresh water and sustaining native biota. Programs of ecosystem rehabilitation and biodiversity conservation in coastal landscapes will be most likely to meet their objectives if they are designed from considerations that include: (1 an integrated perspective that river-estuary systems are influenced by effects of climate change operating on both watersheds and oceans; (2 varying sensitivity among environmental indicators to the uncertainty of future climates; (3 inevitability of

  1. Projected evolution of California's San Francisco Bay-Delta-river system in a century of climate change.

    Science.gov (United States)

    Cloern, James E; Knowles, Noah; Brown, Larry R; Cayan, Daniel; Dettinger, Michael D; Morgan, Tara L; Schoellhamer, David H; Stacey, Mark T; van der Wegen, Mick; Wagner, R Wayne; Jassby, Alan D

    2011-01-01

    Accumulating evidence shows that the planet is warming as a response to human emissions of greenhouse gases. Strategies of adaptation to climate change will require quantitative projections of how altered regional patterns of temperature, precipitation and sea level could cascade to provoke local impacts such as modified water supplies, increasing risks of coastal flooding, and growing challenges to sustainability of native species. We linked a series of models to investigate responses of California's San Francisco Estuary-Watershed (SFEW) system to two contrasting scenarios of climate change. Model outputs for scenarios of fast and moderate warming are presented as 2010-2099 projections of nine indicators of changing climate, hydrology and habitat quality. Trends of these indicators measure rates of: increasing air and water temperatures, salinity and sea level; decreasing precipitation, runoff, snowmelt contribution to runoff, and suspended sediment concentrations; and increasing frequency of extreme environmental conditions such as water temperatures and sea level beyond the ranges of historical observations. Most of these environmental indicators change substantially over the 21(st) century, and many would present challenges to natural and managed systems. Adaptations to these changes will require flexible planning to cope with growing risks to humans and the challenges of meeting demands for fresh water and sustaining native biota. Programs of ecosystem rehabilitation and biodiversity conservation in coastal landscapes will be most likely to meet their objectives if they are designed from considerations that include: (1) an integrated perspective that river-estuary systems are influenced by effects of climate change operating on both watersheds and oceans; (2) varying sensitivity among environmental indicators to the uncertainty of future climates; (3) inevitability of biological community changes as responses to cumulative effects of climate change and other

  2. Projected evolution of California's San Francisco Bay-Delta-River System in a century of continuing climate change

    Science.gov (United States)

    Cloern, James E.; Knowles, Noah; Brown, Larry R.; Cayan, Daniel; Dettinger, Michael D.; Morgan, Tara L.; Schoellhamer, David H.; Stacey, Mark T.; van der Wegen, Mick; Wagner, R. Wayne; Jassby, Alan D.

    2011-01-01

    Background Accumulating evidence shows that the planet is warming as a response to human emissions of greenhouse gases. Strategies of adaptation to climate change will require quantitative projections of how altered regional patterns of temperature, precipitation and sea level could cascade to provoke local impacts such as modified water supplies, increasing risks of coastal flooding, and growing challenges to sustainability of native species. Methodology/Principal Findings We linked a series of models to investigate responses of California's San Francisco Estuary-Watershed (SFEW) system to two contrasting scenarios of climate change. Model outputs for scenarios of fast and moderate warming are presented as 2010–2099 projections of nine indicators of changing climate, hydrology and habitat quality. Trends of these indicators measure rates of: increasing air and water temperatures, salinity and sea level; decreasing precipitation, runoff, snowmelt contribution to runoff, and suspended sediment concentrations; and increasing frequency of extreme environmental conditions such as water temperatures and sea level beyond the ranges of historical observations. Conclusions/Significance Most of these environmental indicators change substantially over the 21st century, and many would present challenges to natural and managed systems. Adaptations to these changes will require flexible planning to cope with growing risks to humans and the challenges of meeting demands for fresh water and sustaining native biota. Programs of ecosystem rehabilitation and biodiversity conservation in coastal landscapes will be most likely to meet their objectives if they are designed from considerations that include: (1) an integrated perspective that river-estuary systems are influenced by effects of climate change operating on both watersheds and oceans; (2) varying sensitivity among environmental indicators to the uncertainty of future climates; (3) inevitability of biological community

  3. 3D seismic analysis of the gas hydrate system and the fluid migration paths in part of the Niger Delta Basin, Nigeria

    Science.gov (United States)

    Akinsanpe, Olumuyiwa T.; Adepelumi, Adekunle A.; Benjamin, Uzochukwu K.; Falebita, Dele E.

    2017-12-01

    Comprehensive qualitative and semi-quantitative seismic analysis was carried out on 3-dimensional seismic data acquired in the deepwater compressional and shale diapiric zone of the Niger Delta Basin using an advanced seismic imaging tool. The main aim of this work is to obtain an understanding of the forming mechanism of the gas hydrate system, and the fluid migration paths associated with this part of the basin. The results showed the presence of pockmarks on the seafloor and bottom simulating reflectors (BSRs) in the field, indicating the active fluid flux and existence of gas hydrate system in the area. In the area of approximately 195 km2 occupying nearly 24% of the entire study field, three major zones with continuous or discontinuous BSRs of 3 to 7 km in length which are in the northeastern, southern and eastern part of the field respectively were delineated. The BSR is interpreted to be the transition between the free gas zone and the gas hydrate zone. The geologic structures including faults (strike-slip and normal faults), chimneys and diapirs were deduced to be the main conduits for gas migration. It is concluded that the biogenic gases generated in the basin were possibly transported via faults and chimneys by advection processes and subsequently accumulated under low temperature and high pressure conditions in the free gas zone below the BSR forming gas hydrate. A plausible explanation for the presence of the ubiquitous pockmarks of different diameters and sizes in the area is the transportation of the excessive gas to the seafloor through these mapped geologic structures.

  4. Central Delta languages: An overview | Kari | Stellenbosch Papers ...

    African Journals Online (AJOL)

    This paper presents an overview of the phonology, morphology and syntax of Central Delta languages. It also provides information on the geo-linguistic, demographic and sociolinguistic situation of these languages. It notes that Central Delta languages have a 20-vowel system, which divides into two sets of 10 vowels ...

  5. Observations of tidal flow, waves and drag within a fringing coastal mangrove forest in the Mekong delta

    Science.gov (United States)

    Mullarney, J. C.; Bryan, K. R.; Henderson, S. M.; Norris, B. K.; Vo Luong, H. P.

    2016-02-01

    In recent years attention has focused on the ability of mangroves to protect shorelines against damage from the combined hydrodynamic forces of waves and tides, owing to the presence of roots (pneumatophores) and tree trunks enhancing vegetative drag. However, field measurements within these dynamic environments are limited. We report on field observations from the seaward side of Cù Lao Dung Island (Soc Trang Province) in the Mekong Delta, Vietnam. The island encompasses two contrasting environments from a sandy, prograding flat with gentle topographic slope on the southwest side to a steep, eroding and muddy fringe region on the northeast side. The data capture the flow transitions from mudflat across the fringing region to the forest interior. We observe a rotation of the obliquely incident flows to an orientation perpendicular to the vegetated/unvegetated boundary. The balances governing the large scale flow are assessed and indicate the relative importance of friction, winds and depth-averaged pressure forces. We find drag coefficients of 10-30 times greater than the usual values associated with bottom friction, with values particularly elevated in the regions of dense pneumatophores that are important during the early stages of the tidal cycle. The field observations are used in the set-up of a simple one-dimensional process model. The model predicts the movement of the tide across the vegetated flat, associated sediment transport and evolution of the across flat profile. Preliminary results indicate that mangrove profiles may evolve towards a close to linear shape in contrast to systems with temperate species or no vegetation.

  6. Tracking Nile Delta vulnerability to Holocene change.

    Science.gov (United States)

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

    2013-01-01

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

  7. Tracking Nile Delta vulnerability to Holocene change.

    Directory of Open Access Journals (Sweden)

    Nick Marriner

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

  8. High-resolution sequence stratigraphy of fluvio-deltaic systems: Prospects of system-wide chronostratigraphic correlation

    Science.gov (United States)

    Dalman, Rory; Weltje, Gert Jan; Karamitopoulos, Pantelis

    2015-02-01

    A basin-scale numerical model with a sub-grid parameterization of fluvio-deltaic processes and stratigraphy was used to study the relation between alluvial sedimentation and marine deltaic deposition under conditions of time-invariant forcing. The experiments show that delta evolution is governed by a robust morphodynamic feedback loop, which provides a link between major avulsions, delta-lobe switches, and sequestration of sediments on the delta plain. Major avulsions, driven by local superelevation, result in abandonment of delta lobes and initiation of new lobes. Progradation of the delta front lengthens the fluvial profile and reduces its gradient, which induces aggradation upstream. The aggradation, in turn, causes local superelevation of the channel belt. Each major avulsion causes a wave of incision to migrate upstream, whereas downstream of the avulsion point, the rate of aggradation temporarily increases until a new equilibrium situation has been established. The feedback loop explains storage and release of fluvial sediments without the need to invoke changes in upstream or downstream controls and provides a plausible mechanism for the generation of high-frequency incision-aggradation cycles as the sole result of compensational stacking. The stratigraphic expression of a depocentre shift is an essentially isochronous surface. Hence, the stratigraphic record of fluvio-deltaic systems may be subdivided into a series of units representing intervals during which a channel belt and delta lobe were forming at a fixed location in the basin, so-called chronosomes. Fluvio-deltaic chronosomes are bounded by abandonment surfaces, which are clearly expressed in the marine as well as the fluvial domain. The surface marking the abandonment of a particular channel belt and delta lobe correlates with the surface at the base of a new delta lobe. Landward, this surface forms the base of an aggradational package of fluvial sediments downstream of an avulsion site associated

  9. Delta capability for launch of communications satellites

    Science.gov (United States)

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

    1982-01-01

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

  10. High resolution carbon isotope of Crassostrea cuttakensis: A proxy for seasonally varying carbon dynamics in a tropical delta-estuary system

    Science.gov (United States)

    Sreemany, Arpita

    2017-04-01

    The exponential increase in the atmospheric CO2 concentration and global temperature is becoming a major threat to the existence of the mankind. It has been proposed that the ˜2 ˚ C rise in the average global temperature may lead to a point of no-return where the balance between the climate and the ecosystem collapses. Therefore, detailed understanding of the major carbon reservoirs and their mutual interactions is needed for better future climate prediction. Among all the reservoirs, ocean holds ˜90 % of the exogenic carbon and promotes long term storage in sediments. However, the majority of the sedimentary carbon is of terrestrial origin and transported through rivers, which play an important role in carbon exchange between the atmosphere, terrestrial biosphere, and oceans. The transportation of organic carbon through river does not follow a simple conveyer belt model. Various organic and inorganic reactions (i.e., organic carbon degradation, inorganic carbon precipitation, primary production, community respiration) modify the state of the carbon to form a major sub-reservoir in the river, i.e., Dissolved Inorganic Carbon (DIC). So, identifying the source/s of the DIC is crucial to understand the carbon dynamics in the river. Stable carbon isotopic composition of the DIC (δ13CDIC) has long been extensively used to reveal the dominant source/s of the DIC. The majority of the large rivers, being situated in the tropical belts, show seasonal fluctuation in the DIC sources. However, seasonal sampling in the remotest reaches of these rivers hindered our thorough understanding of the seasonally varying source/s of DIC in these rivers. Many calcifying organisms precipitate their shell carbonate in equilibrium with water and hence likely to record the δ13CDICof ambient water in their shell. In this study, a living oyster (Crassostrea cuttakensis) was collected from Matla River, which is part of the Ganges Brahmaputra river delta system, and analyzed for its stable

  11. {\\delta}M Formalism

    OpenAIRE

    Talebian-Ashkezari, Alireza; Ahmadi, Nahid; Abolhasani, Ali Akbar

    2016-01-01

    We study the evolution of the "non-perturbative" metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the "{\\delta}M formalism" for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so...

  12. Nicotine-induced CREB and DeltaFosB activity is modified by caffeine in the brain reward system of the rat.

    Science.gov (United States)

    Kowiański, Przemysław; Lietzau, Grażyna; Steliga, Aleksandra; Czuba, Ewelina; Ludkiewicz, Beata; Waśkow, Monika; Spodnik, Jan H; Moryś, Janusz

    2017-11-01

    Coffee and nicotine consumption are frequently combined, indicating possible intensifying effect of caffeine on smoking behavior, although neurobiological background of this phenomenon remains unknown. We aimed at determining the effect of caffeine and nicotine, applied separately or simultaneously, on activation of six structures of the brain reward system: nucleus accumbens (NAc), ventral tegmental area (VTA), amygdala (Amg), hippocampus (Hip), medial prefrontal cortex (mPfr) and dorsal striatum (CdP) in the adult male Wistar rats. Activation of two transcription factors, the phosphorylated form of cyclic AMP-response element binding protein (pCREB) and DeltaFosB (ΔFosB) was assessed by immunohistochemistry after multiple-dose five-days psychostimulants administration followed by 20min and 24h survival, respectively. Nicotine evoked the highest increase of pCREB-immunoreactivity (-ir) in NAc, while caffeine exerted the weakest effect in mPfr and CdP. Nicotine/caffeine co-administration resulted in decrease of pCREB-ir in NAc and increase in Amg, compared with the effect of each psychostimulant used separately. Nicotine was the strongest psychostimulant activating ΔFosB-ir in Amg, whereas caffeine - in Hip. Nicotine/caffeine-exerted effect upon ΔFosB-ir in Amg was weaker, whereas in mPfr stronger, than nicotine-evoked effect in these structures. In summary, pCREB and ΔFosB activation is dependent on the type of stimulus, brain structure and functional context. Activation of both transcription factors is responsible for caffeine's modifying effect upon nicotine-related behaviors and must be taken into account while quitting cigarette smoking. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Delta Semantics Defined By Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kyng, Morten; Madsen, Ole Lehrmann

    This report is identical to an earlier version of May 1978 except that Chapter 5 has been revised. A new paper: "A Petri Net Definition of a System Description Language", DAIMI, April 1979, 20 pages, extends the Petri net model to include a data state representing the program variables. Delta...

  14. Biomechanical comparison of the bioabsorbable RetroScrew system, BioScrew XtraLok with stress equalization tensioner, and 35-mm Delta Screws for tibialis anterior graft-tibial tunnel fixation in porcine tibiae.

    Science.gov (United States)

    Chang, Haw Chong; Nyland, John; Nawab, Akbar; Burden, Robert; Caborn, David N M

    2005-07-01

    Achieving effective soft tissue graft-tibial tunnel fixation remains problematic. No differences would exist for tibialis anterior graft-tibial tunnel fixation when comparing the RetroScrew System (20-mm retrograde screw, 17-mm antegrade screw), the 35-mm tapered Delta Screw (manual tensioning), and the 35-mm BioScrew XtraLok (applied using an instrumented tensioner). Controlled laboratory study. Porcine tibiae (apparent bone mineral density, 1.3 g/cm(2)) and human tendon allografts were divided into 3 matched groups of 6 specimens each before cyclic (500 cycles, 50-250 N, 1 Hz) and load-to-failure (20 mm/min) tests. The BioScrew XtraLok (210.9 +/- 54.9 N/mm) and the 35-mm Delta Screw (224.3 +/- 43.7 N/mm) displayed superior stiffness to the RetroScrew System (114.1 +/- 23.3 N/mm) (P = .0004) during cyclic testing. The BioScrew XtraLok (1.0 +/- 0.2 mm) and the Delta Screw (0.9 +/- 0.2 mm) also displayed less displacement during cyclic testing than the RetroScrew System (1.8 +/- 0.5 mm) (P = .001). During load-to-failure testing, the BioScrew XtraLok withstood greater loads (1436.3 +/- 331.3 N) (P = .001) and displayed greater stiffness (323.6 +/- 56.8 N/mm) (P = .002) than the 35-mm Delta Screw (load, 1042.2 +/- 214.4 N; stiffness, 257.2 +/- 22.2 N/mm) and the RetroScrew System (load, 778.7 +/- 177.5 N; stiffness, 204.4 +/- 52.9 N/mm). The BioScrew XtraLok with instrumented tensioning displayed superior fixation to the RetroScrew System and the 35-mm Delta Screw applied with manual tensioning. The BioScrew XtraLok may provide superior soft tissue graft-tibial tunnel fixation. Further in vitro studies using human tissue and in vivo clinical studies are needed.

  15. Assessment of Heavy Metal Pollution and Health Risks in the Soil-Plant-Human System in the Yangtze River Delta, China

    Science.gov (United States)

    Hu, Bifeng; Jia, Xiaolin; Hu, Jie; Xu, Dongyun; Xia, Fang; Li, Yan

    2017-01-01

    Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10−3) was the largest among three age groups, followed by adults (6.998 × 10−4) and seniors (5.488 × 10−4). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni

  16. Assessment of Heavy Metal Pollution and Health Risks in the Soil-Plant-Human System in the Yangtze River Delta, China.

    Science.gov (United States)

    Hu, Bifeng; Jia, Xiaolin; Hu, Jie; Xu, Dongyun; Xia, Fang; Li, Yan

    2017-09-10

    Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10-3) was the largest among three age groups, followed by adults (6.998 × 10-4) and seniors (5.488 × 10-4). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni (0

  17. Lack of Association of C-C Chemokine Receptor 5 Delta 32 Deletion Status with Rheumatoid Arthritis, Systemic Lupus Erythematosus, Lupus Nephritis, and Disease Severity

    NARCIS (Netherlands)

    Martens, Henk A.; Gross, Sacha; van der Steege, Gerrit; Brouwer, Elisabeth; Berden, Jo H. M.; de Sevaux, Ruud; Derksen, Ronald H. W. M.; Voskuyl, Alexandre E.; Berger, Stefan P.; Navis, Gerjan J.; Kallenberg, Cees G. M.; Bijl, Marc

    2010-01-01

    Objective. C-C chemokine receptor 5 (CCR5) plays an important role in inflammation. A 32 base-pair (Delta 32) deletion in the CCR5 gene leads to a nonfunctional receptor. This deletion has been reported to have a protective effect on the development and progression of several autoimmune diseases. We

  18. Spatial heterogeneity of sources of branched tetraethers in shelf systems: The geochemistry of tetraethers in the Berau River delta (Kalimantan, Indonesia)

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.

    2016-01-01

    The bulk organic matter composition (total organic carbon (TOC) content and d13CTOC) and composition of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGT) in surface sediments from 43 stations in the Berau River delta (east Kalimantan, Indonesia), including two coast-shelf

  19. Determination Of Ornithological Richness Of Erek Lake Dneme And Bendimahi Deltas VanTurkey In Winter Season And Mapping With Geographic Information System

    Directory of Open Access Journals (Sweden)

    Atilla Durmuamp351 Emrah elik

    2017-04-01

    Full Text Available Basin of Lake Van is very rich in all seasons in terms of ornithology. Birds that find alternative habitats in the basin outside winter season become dense in certain regions. Species and population sizes of water birds in Ercek lake Dneme and Bendimahi Deltas in winter were researched in this study. Bird species and their population sizes were determined as a result of observations covering November-February months of 2013-2014 and 2014-2015. As a result of two-year winter counts a total of 7563 individuals belonging to 20 species were counted in Dneme Delta 2489 individuals were counted in Erek Lake and Coot Fulica atra was determined as dominant species in both areas. A total of 1623 individuals belonging to 20 species were counted in Bendimahi Delta and Mallard Anas platyrhynchos was determined as dominant species. A total of 54 individuals from Common Pochard Aythya ferina species in VU Vulnerable category were counted in Bendimahi Delta according to International IUCN Red List criteria. Population densities of 5 different habitats in the area were determined and numerical thematic distribution maps were created by being processed in ArcMap 10.2.

  20. Tectonic Uplift and Fan Delta Incision along the Conway Coast, NZ

    Science.gov (United States)

    Burtt, D. G.; Bassett, K. N.

    2015-12-01

    The Conway Coast features a unique confluence of fan deltas, terrace uplift, and transpressional faulting. Thrust faults have caused the uplift of the Hawkeswood Range which provides sediment sources for local Gilbert-type fan deltas uplifting to form terraces. Sediments are characterized by steeply dipping foreset beds, horizontal topset beds and tangential bottomset beds. These fan deltas tend to form on steep basin margins often associated with extensional faulting. However, the Conway coast is dominated by thrust faulting. The Rafa terrace, dated between 52.4±4.5 and 79.0±3.5 ka with Optically Stimulated Luminescence, is exposed in cliff faces on the beach. Local creek channels deposited the fan deltas and later incised older deposits to reveal a three-dimensional perspective of the fan delta. This perspective is vital to the recreation of the fan delta position and channel avulsion, leading to a better understanding of the role of uplift superimposed by sea level change in the formation of the terraces. Forty-three photographs were stitched together to form an extensive photomosaic. The types of sediments, significant structures and relationships between adjacent beds were noted and analyzed. Correlations between the sedimentary architecture and sea level change were made using a sea level curve of the South Pacific over the last 140 ka. The incision of mud by gravel producing large flame structures suggests that there was a drop in sea level and a subsequent progradation of the fan delta. Based on the sea level curve, this drop occurred between ~66-79 ka. Higher in the fan delta, a fining-upward sequence points to a rise in sea level. This correlates with a rise on the sea level curve between ~52-63 ka. Upsection there is another coarsening-upward sequence of 5-10 m thick beds suggesting a fall in sea level before the uplift and incision of the terrace and the subsequent formation of the Ngaroma terrace. Due to their lateral extent, the gravels seem to

  1. Correlations between vegetation and island geomorphology in the Wax Lake Delta, Louisiana

    Science.gov (United States)

    Smith, B. C.; Moffett, K. B.; Mohrig, D. C.

    2013-12-01

    Understanding how deltas build and maintain themselves is critical to predicting how they will respond to perturbations such as sea level rise. This is especially an issue of interest in coastal Louisiana, where land loss is prevalent due to subsidence and decreased sediment supply. Feedbacks between ecology and geomorphology have been well documented in many different environments, but the role of vegetation in delta morphodynamics is not well understood. This study investigates spatial and temporal correlations between vegetation succession and sediment accumulation at the Wax Lake Delta in Louisiana. This low gradient, rapidly prograding, tidally influenced delta has been forming since 1973 at the mouth of the man-made Wax Lake Outlet discharging into Atchafalaya Bay. We established a 2500 m long transect along the western levee of Pintail Island, capturing the full range of island elevations and the transition from bare sediment to herbaceous plants and trees. Shallow (50-150 cm deep) sediment cores from this transect were analyzed for particle size, organic matter content, and bulk density, and dated using Pb-210. The resulting sedimentation rates and composition trends over time were compared to remote sensing-based analyses of temporal changes in vegetation extent, island shape, and flooding frequency derived from historical aerial photos and Landsat images. We find that significantly more silty and organic sediments overly fine sandy deposits, with a greater depth to sand at higher elevations. Although the depth of the textural transition might logically be related to the local mean water level along the island elevation transect, trends in flooding frequency extracted from the historical series of Landsat images show that island elevations relative to mean water level have changed over time. These results provide an empirical foundation for future mechanistic models linking mineral sedimentation, organic sedimentation, vegetation succession, elevation

  2. Indução de resistência sistêmica à antracnose em feijoeiro-comum pela raça delta avirulenta de Colletotrichum lindemuthianum Induction of systemic resistance to anthracnose in common bean by the avirulent delta race of Colletotrichum lindemuthianum

    Directory of Open Access Journals (Sweden)

    Ângela Diniz Campos

    2009-01-01

    Full Text Available O objetivo deste trabalho foi avaliar o potencial da raça delta avirulenta do fungo Colletotrichum lindemuthianum, como protetora contra raças virulentas deste fungo e quanto à capacidade de induzir resistência sistêmica em feijoeiro-comum (Phaseolus vulgaris. Quatro cultivares de feijoeiro foram avaliadas quanto às alterações nas atividades de beta 1,3 glucanase e quitinase, em dois estádios de desenvolvimento (V2 e R6, três dias após a aplicação de suspensão de esporos de C. lindemuthianum raça delta avirulenta, em comparação com aplicações de água e ácido salicílico. As plantas foram, então, infectadas com o patótipo virulento 33/95 de C. lindemuthianum em suspensão e, depois de cinco dias, foram reavaliadas quanto à atividade das enzimas. Observaram-se acréscimos significativos nas atividades da beta 1,3 glucanase e quitinase, após inoculação do fungo indutivo, nas duas avaliações, nos dois estádios de desenvolvimento. As atividades da beta 1,3 glucanase e da quitinase variaram entre as cultivares e entre os estádios de desenvolvimento das plantas. A correlação entre o índice de severidade da doen��a e a atividade das enzimas foi altamente significativa. O uso de C. lindemuthianum raça delta avirulenta diminuiu a severidade da doença e pode ter potencial para controlar a antracnose do feijoeiro.The objectives of this work were to evaluate the potential of the avirulent delta race of Colletotrichum lindemuthianum as a protector against virulent races of this fungus and induce systemic resistance to anthracnose in common bean (Phaseolus vulgaris. Four common bean cultivars were evaluated for changes in the activities of beta-1,3-glucanase and chitinase at two common bean developmental stages, V2 and R6, three days after the infection with delta race of C. lindemuthianum, in comparison with control applications of water and salicylic acid. The plants were then infected with a spore suspension of 33

  3. The magnetic phase diagram of the spin-chain system Ca{sub 2+x}Y{sub 2-x}Cu{sub 5}O{sub 10-{delta}}: Oxygen hole-doping corrections

    Energy Technology Data Exchange (ETDEWEB)

    Park, Keeseong [Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, TX 78712 (United States)], E-mail: kspark@physics.utexas.edu; Lee, Yong J.; Markert, John T. [Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, TX 78712 (United States)

    2007-09-01

    Recently, the antiferromagnetic transition temperature in the coupled spin-chain system Ca{sub 2+x}Y{sub 2-x}Cu{sub 5}O{sub 10-{delta}} was found to decrease with increasing x and disappear around x = 1.4 [K. Kubo, S. Kurogi, Y. Koike, T. Nishizaki, N. Kobayashi, Phys. Rev. B 71 (2005) 104413]. We report the results of X-ray diffraction, magnetic susceptibility, heat capacity, and iodometric titration measurements, and find that such behavior corresponds to oxygen-deficient specimens. We propose that the correct phase diagram is a function of both cation doping and oxygen content, with hole concentration p = (x - 2{delta}) per formula unit. We find that the true phase transition occurs just below p = 1.0, corresponding to a hole concentration of 0.20 per copper. For example, for x = 1.00, the single crystals of Kubo et al. (2005) correspond to our polycrystalline specimens with {delta} = 0.37 (p = 0.26), a very large oxygen-defect effect. Such a composition has only a slightly suppressed Neel temperature, while for our fully oxygenated x = 1.00 samples, the antiferromagnetic transition is completely suppressed.

  4. Oxygen hole-doping effects on the spin-chain system Ca{sub 2+x}Y{sub 2-x}Cu{sub 5}O{sub 10-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Park, K. [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: kspark@physics.utexas.edu; Cackowski, T. [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States); Markert, J.T. [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: markert@physics.utexas.edu

    2008-04-01

    The magnetic properties of the low-dimensional spin-chain system Ca{sub 2+x}Y{sub 2-x}Cu{sub 5}O{sub 10-{delta}} were studied as a function of oxygen content and Ca-doping. A series of samples with different oxygen contents were prepared by solid state reaction under various oxygen pressures up to 170 atm and characterized by X-ray diffraction and iodometric titration. Oxygen deficiency was observed to be from {delta}=0.2-0.4 at 0.2 atm to {delta}{approx}0.0 at 170 atm oxygen pressure. Oxygen deficiency increases with Ca-doping at fixed oxygen pressure. The temperature dependence of the magnetic moment and of the specific heat are reported here for the x=0.9 sample with various oxygen deficiencies. The effects of oxygen deficiency on magnetic coupling are compared with Ca-doping. Notably, oxygen content plays a much more critical role in the reduction of magnetic interactions in the CuO{sub 2} chains than Ca-doping, even for the same hole concentration.

  5. Peat compaction in deltas : implications for Holocene delta evolution

    NARCIS (Netherlands)

    van Asselen, S.

    2010-01-01

    Many deltas contain substantial amounts of peat, which is the most compressible soil type. Therefore, peat compaction potentially leads to high amounts of subsidence in deltas. The main objective of this research was to quantify subsidence due to peat compaction in Holocene fluvial-deltaic settings

  6. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

    1999-01-01

    Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia

  7. Challenges, Approaches and Experiences from Asian Deltas and the Rhine-Meuse Delta : Regional Training Workshop on Delta Planning and Management

    NARCIS (Netherlands)

    Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

    2013-01-01

    River delta's, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Ayeyarwady Delta (Myanmar), Nile (Egypt) and Ciliwung Delta (Indonesia) are developing rapidly and are characterised by large-scale urbanisation and industrialization processes. They are facing serious planning

  8. Mida pakub Delta? / Teele Kurm

    Index Scriptorium Estoniae

    Kurm, Teele

    2011-01-01

    Politsei- ja Piirivalveamet võtab kasutusele ühise Siseministeeriumi infotehnoloogia- ja arenduskeskuse ning Webmedia AS koostööna loodud dokumendihaldussüsteemi Delta. Kust sai Delta oma nime? Projekti "Dokumendihaldussüsteemi juurutamine Siseministeeriumi haldusalas" eesmärgid

  9. Challenges from the Niger Delta

    African Journals Online (AJOL)

    User

    2012-01-24

    Jan 24, 2012 ... leadership that we are going to consider the state of security in the Niger. Delta region. Vol. ... what Bolade and Adelemo. National Security and Sustainable Development in Nigeria: Challenges from the Niger Delta .... development theory adopts a holistic approach that is mindful of the future implications of ...

  10. The Niger Delta Prob em

    African Journals Online (AJOL)

    Edlyne E Anugwom: Ethnicity, Federalism and Revenue Allocation in a Democratic Nigeria: The Niger Delta Problem. Ethnicity, Federalism and_Revenue. Allocation in a Democratic Ni eria. The Niger Delta Prob em. By Edlyne E. Anugwom. Department of Sociology/Anthropology,. University of Nigeria, Nsukka. Nigeria.

  11. Delta isobars in neutron stars

    Directory of Open Access Journals (Sweden)

    Pagliara Giuseppe

    2015-01-01

    Full Text Available The appearance of delta isobars in beta-stable matter is regulated by the behavior of the symmetry energy at densities larger than saturation density. We show that by taking into account recent constraints on the density derivative of the symmetry energy and the theoretical and experimental results on the excitations of delta isobars in nuclei, delta isobars are necessary ingredients for the equations of state used for studying neutron stars. We analyze the effect of the appearance of deltas on the structure of neutron stars: as in the case of hyperons, matter containing delta is too soft for allowing the existence of 2M⊙ neutron stars. Quark stars on the other hand, could reach very massive configurations and they could form from a process of conversion of hadronic stars in which an initial seed of strangeness appears through hyperons.

  12. DELTA 3D PRINTER

    Directory of Open Access Journals (Sweden)

    ȘOVĂILĂ Florin

    2016-07-01

    Full Text Available 3D printing is a very used process in industry, the generic name being “rapid prototyping”. The essential advantage of a 3D printer is that it allows the designers to produce a prototype in a very short time, which is tested and quickly remodeled, considerably reducing the required time to get from the prototype phase to the final product. At the same time, through this technique we can achieve components with very precise forms, complex pieces that, through classical methods, could have been accomplished only in a large amount of time. In this paper, there are presented the stages of a 3D model execution, also the physical achievement after of a Delta 3D printer after the model.

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

    Science.gov (United States)

    Bruns, Daniel; Klebanov, Vladimir; Schaefer, Ina

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

  14. La formation de l'inkisi (Supergroupe ouest-congolien) en Afrique centrale (Congo et Bas-Zaïre): un delta d'âge Paléozoïque comblant un bassin en extension

    Science.gov (United States)

    Alvarez, Philippe; Maurin, Jean-Christophe; Vicat, Jean-Paul

    1995-02-01

    The Inkisi Formation (West Congolian Supergroup) corresponds to a large deltaic body, which extends through Congo, Lower Zaire and Angola. In the Congo and Lower Zaire areas, the lower part of this formation is characterized by a fluvial conglomerate with elliptic pebbles. The red arkosic, channelized series from the Brazzaville-Kinshasa area involves delta plain distributary channels and delta front sequences. The transport direction of continental material is from north to south and the source area is the Chaillu basement. Glacial quartzitic pebbles are probably reworked from the fluvio-lacustrine Upper Diamictite Formation. The classical subdivisions of the Inkisi Formation - basal conglomerate (I 0), Lower part (I 1) and Upper part (I 2) - are not used. These subdivisions correspond to a fluvial conglomerate and to delta front and delta plain facies. The coastal onlap progressively covered the conglomerate and the distributary channels in the delta plain was prograding onto the delta front. The prodelta sequence could correspond to the Upper level of the Mpioka molassic Formation. The Inkisi delta was on the northern edge of an extensional basin controlled by NE-SW normal faults. The extension phase is dearly post Pan-African and occurred during the Palaeozoic, probably in relation to the Permian Karoo phase, and is also known in Angola.

  15. The Nice model can explain the dispersion of the prograde Himalia family of irregular satellites at Jupiter

    Science.gov (United States)

    Li, Daohai; Christou, Apostolos

    2017-10-01

    More than 50 irregular satellites revolve around Jupiter in which at least three distinct collisional families are identified. Among them, the Himalia family is unique in the large velocity dispersion--several hundred m/s--among its members, inconsistent with a purely collisional origin.We explore this puzzle in the context of the Nice scenario of early solar system evolution. There, the giant planets migrated significant distances due to interactions with a primordial planetesimal disk. We generate a synthetic, collisionally-produced Himalia family and follow its evolution through principal events of the Nice model. Two situations are considered: (i) The planetesimal disk is solely composed of large, moon-sized objects. In this case, the family is dramatically scattered, especially in semimajor axis and eccentricity, as the planetesimals fly by Jupiter. The velocity dispersion of $\\sim60\\%$ of family members is raised to several hundred m/s, satisfactorily explaining the observed dispersion. However, this situation is not likely as the considered planetesimals seem unphysically massive. We now consider the alternative case (ii) within the so-called ``Jumping Jupiter’’ where planetary, rather than planetesimal encounters are responsible for the observed dispersion. Here, ice giants encounter Jupiter up to a few hundred times (Nesvorn\\'{y} \\& Morbidelli 2012). We find $\\lesssim20$ such planetary encounters disperse the synthetic family to the observed degree. We also find that the family cannot survive $\\sim100$ such fly-bys as the satellites become too widely dispersed.Reference: Nesvorn\\'{y}, D., \\& Morbidelli, A. 2012, AJ, 144, 117.

  16. Al zoning in pyroxene and plagioclase: Window on late prograde to early retrograde P-T paths in granulite terranes

    Energy Technology Data Exchange (ETDEWEB)

    Anovitz, L.M. (Univ. of Arizona, Tucson (United States))

    Clino-and orthopyroxenes in granulites commonly show significant Al zoning typified by Al-rich cores and Al-poor rims. Zoning-relaxation calculations suggest that relaxation of Al growth zoning in pyroxenes and plagioclases during peak metamorphism is minor. Thus, Al-zoning data may be used to examine that part of the granulite P-T path along which pyroxene grew. The slope of the log K curves for the reaction CaTs + quartz = anorthite is negative below 20 kbar whereas that for jadeite + quartz = albite is positive, and the two may be combined to yield both pressure and temperature. A subregular quaternary activity model for the system CaTs-jadeite-diopside-hedenbergite was fitted for these calculations. Data for four granulite terranes were examined. Calculations for the Grenville Province, Ontario, yield decreasing pressures and temperatures and an average dP/dT of 54 bars/{degree}C. The average rim results (10.1 kbar, 860C) agree well with peak P-T values (10 kbar, 800-850C) obtained by other methods. Average core results (12.8 kbar, 910C) are significantly higher and suggest prepeak unloading. Data from the Furua Complex, Tanzania, are similar to those from the Grenville (core = 13.7 kbar, 930C; rim = < 11.6 kbar, < 845C), but yield only limits for the rim P-T because plagioclase rim compositions were not obtained. In the Fiordland complex, both Fe-Mg and Al zoning (core = 6.7 kbar, 650C; rim = 14.8 kbar, 810C) are in reasonable agreement and suggest an increase in P. Results from the Pikwitonei area, Manitoba, yield retrograde P-T paths (core = 6.7 kbar, 830C; rim = 3.3 kbar, 670C; 21 bars/{degree}C), and zoning patterns in the feldspar suggest that plagioclase may have grown during retrogression.

  17. Simulation and validation of larval sucker dispersal and retention through the restored Williamson River Delta and Upper Klamath Lake system, Oregon

    Science.gov (United States)

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.

    2014-01-01

    A hydrodynamic model with particle tracking was used to create individual-based simulations to describe larval fish dispersal through the restored Williamson River Delta and into Upper Klamath Lake, Oregon. The model was verified by converting particle ages to larval lengths and comparing these lengths to lengths of larvae in net catches. Correlations of simulated lengths with field data were moderate and suggested a species-specific difference in model performance. Particle trajectories through the delta were affected by wind speed and direction, lake elevation, and shoreline configuration. Once particles entered the lake, transport was a function of current speed and whether behavior enhanced transport (swimming aligned with currents) or countered transport through greater dispersal (faster random swimming). We tested sensitivity to swim speed (higher speeds led to greater dispersal and more retention), shoreline configuration (restoration increased retention relative to pre-restoration conditions), and lake elevation (retention was maximized at an intermediate elevation). The simulations also highlight additional biological questions, such as the extent to which spatially heterogeneous mortality or fish behavior and environmental cues could interact with wind-driven currents and contribute to patterns of dispersal.

  18. Differentiating climatic- and tectonic-controlled lake margin in rift system: example of the Plio-Quaternary Nachukui Formation, Turkana depression, Kenya

    Science.gov (United States)

    Alexis, Nutz; Mathieu, Schuster; Abdoulaye, Balde; Jean-Loup, Rubino

    2016-04-01

    The Turkana Depression is part of the eastern branch of the East African Rift System. This area consists of several Oligo-Pliocene north-south oriented half-grabens that connect the Ethiopian and Kenyan rift valleys. Exposed on the west side of the Lake Turkana, the Nachukui Formation represents a Plio-Quaternary syn-rift succession mainly outcropping near the border fault of the North Lake basin. This Formation consists of a > 700 m thick fluvial-deltaic-lacustrine sediments deposited in this area between 4.2 and 0.5 Ma. In this contribution, we present preliminary results from the investigation of the complete succession based on field geology. Facies description and sequence analyses are provided focusing on lake margin evolution through time and deciphering their controlling factors. Two main types of facies association can be distinguished in the Nachukui Fm and reveal two main types of lake margins that alternatively developed in the Turkana basin. Type-1 is characterized by thick conglomeratic proximal alluvial fan fining laterally from the border fault to the central portion of the lake to gravelly distal alluvial fan. Conglomerate and gravel beds display recurrent wave reworking (ripples, clasts sorting, open-work), as well as intercalated shells placer and stromatolites beds. Laterally, facies rapidly grade to offshore siliciclastic muds. These facies are interpreted as aggrading and prograding coarse fan deltas that entered directly in the lake. Their subaqueous parts were then affected by waves and allowed the development of shell placers and stromatolite reefs. This facies association is generally included in thick packages representing long-term prograding trends of several hundred thousand years duration (> 500 ka). Type-2 is characterized by poorly developed alluvial fan near the border fault, rapidly grading laterally to a fluvial plain and then to well-developed wave-dominated coast (beaches, washover fans, coastal wedges), finally connected to

  19. Delta-ALA urine test

    Science.gov (United States)

    ... be used to help diagnose a condition called porphyria . Normal Results Normal value range for adults is ... of urinary delta-ALA may indicate: Lead poisoning Porphyria (several types) A decreased level may occur with ...

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

    Science.gov (United States)

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

    2013-12-01

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

  1. Supersonic aerodynamics of delta wings

    Science.gov (United States)

    Wood, Richard M.

    1988-01-01

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

  2. Deltaic System in the Southern Shelf of the Ulleung Back-Arc Basin, East Sea, Korea

    Science.gov (United States)

    Ko, Jaehong; Yoon, Junil

    2017-04-01

    The Ulleung basin is one of back-arc basins in the East Sea of Korea with the Japan and Yamato basins, formed as a result of extension behind the Japanese island-arc in Miocene. Its shelf basin was constructed by stacked prograding deltaic sequences over 10 km in thickness. The basin is platformal in the northwest, and folded and faulted by thrusts in the southeast. Deformation occurred around 12.5 Ma, the timing of which is related to collision of the Izu-Bonin arc against the Japan Island. The deformed and uplifted blocks were peneplained in 6.3 Ma. N-S trending broad folding occurred recently in the platformal shelf area. Three depositional sequences, separated by unconformities of 12.5 and 6.3 Ma, represent the major transgressive-regressive-transgressive cycles of the Ulleung back-arc shelf. Each cycle corresponds to opening and continuous subsidence, destruction of back-arc due to compression, and post-closure regional subsidence, respectively. The deltaic system consisting the depositional sequences includes coastal, delta plain, delta front, prodelta and deep water facies, each being distinctive in log and seismic characteristics. The coastal facies are characterized by serrated gamma log responses and discontinuous seismic reflectors suggesting fluvial formation: delta plain by association of fining-upward cycles and shale-filled distributary channels: delta front by blocky or coarsening upward log responses: prodelta by shale dominance and low seismic impedance: and deep water by thick sandstone-shale combinations interpreted as submarine fan complexes.

  3. Pteridophytes of the Okavango Delta, Botswana (Southern Africa

    Directory of Open Access Journals (Sweden)

    Vega Hernández, Efrén

    2000-12-01

    Full Text Available The Okavango Delta in Botswana constitutes one of the larger inland deltas in the world. Fifteen species of fern were found in this ecological system integrated into 10 genera and 9 families. Included in this report are descriptions of each family, genus and species. Also given are artificial keys to the genera, as well as keys for genera and species within the family when necessary. A documented distribution and ecological notes for each species also appears.Se estudian los pterid6fitos del delta del Okavango, uno de los deltas interiores ma's grandes del mundo. Se citan 15 especies, incluidas en 10 generos y 9 familias. Se aportan descripciones, claves de identification, datos sobre la distribucitin y ecologia. y mapas de distribuci6n detallada de cada una de las especies.

  4. Reduction of bias in static closed chamber measurement of delta13C in soil CO2 efflux.

    Science.gov (United States)

    Ohlsson, K E Anders

    2010-01-01

    The (13)C/(12)C ratio of soil CO(2) efflux (delta(e)) is an important parameter in studies of ecosystem C dynamics, where the accuracy of estimated C flux rates depends on the measurement uncertainty of delta(e). The static closed chamber method is frequently used in the determination of delta(e), where the soil CO(2) efflux is accumulated in the headspace of a chamber placed on top of the soil surface. However, it has recently been shown that the estimate of delta(e) obtained by using this method could be significantly biased, which potentially diminish the usefulness of delta(e) for field applications. Here, analytical and numerical models were used to express the bias in delta(e) as mathematical functions of three system parameters: chamber height (H), chamber radius (R(c)), and soil air-filled porosity (theta). These expressions allow optimization of chamber size to yield a bias, which is at a level suitable for each particular application of the method. The numerical model was further used to quantify the effects on the delta(e) bias from (i) various designs for sealing of the chamber to ground, and (ii) inclusion of the commonly used purging step for reduction of the initial headspace CO(2) concentration. The present modeling work provided insights into the effects on the delta(e) bias from retardation and partial chamber bypass of the soil CO(2) efflux. The results presented here supported the continued use of the static closed chamber method for the determination of delta(e), with improved control of the bias component of its measurement uncertainty. Copyright 2009 John Wiley & Sons, Ltd.

  5. Natural and anthropogenic influences on depositional architecture of the Ural Delta, Kazakhstan, northern Caspian Sea, during the past 70 years

    Science.gov (United States)

    Scarelli, Frederico M.; Cantelli, Luigi; Barboza, Eduardo G.; Gabbianelli, Giovanni

    2017-05-01

    This paper focuses on the Ural Delta in the northern zone of the Caspian Sea, an area with particular characteristics, where intense influence from anthropogenic and natural factors exists, which acts on the fragile delta system. We built a database to integrate the data from the published sources, bathymetric survey, and recent images in the geographical information system (GIS) environment. The results were linked to the Caspian Sea level (CSL) curve, which had many variations, changing the Ural Delta system's dynamics and in its architecture. In addition, the anthropogenic changes contribute to shaping the actual Ural Delta architecture. Through the link between the results and CSL, we reconstructed an evolution model for the Ural Delta system for the last century and identified three different architectures for the Ural Delta, determined by the energy that acted on the system in the last century and by the anthropogenic changes. This work identifies six different delta phases, which are shaped by CSL changes during the last 70 years and by anthropogenic changes. The delta phases recognized are: i) a Lobate Delta phase, shaped during high CSL before 1935; ii) Natural Elongate Delta 1935-1950 formed during rapid CSL fall; iii) Anthropogenic Elongate Delta 1950-1966, formed during rapid CSL fall and after the Ural-Caspian Sea canal construction, which modified the sedimentary deposition on the delta; iv) Anthropogenic Elongate Delta 1966-1982 shaped during low CSL phase; v) Anthropogenic Elongate Delta 1982-1996 formed during a rapid CSL rise phase; and vi) Anthropogenic Elongate Delta 1996-2009 shaped during high CSL that represent the last phase and actual Ural Delta architecture.

  6. Delta1 expression, cell cycle exit, and commitment to a specific secretory fate coincide within a few hours in the mouse intestinal stem cell system.

    Directory of Open Access Journals (Sweden)

    Despina Stamataki

    Full Text Available The stem cells of the small intestine are multipotent: they give rise, via transit-amplifying cell divisions, to large numbers of columnar absorptive cells mixed with much smaller numbers of three different classes of secretory cells--mucus-secreting goblet cells, hormone-secreting enteroendocrine cells, and bactericide-secreting Paneth cells. Notch signaling is known to control commitment to a secretory fate, but why are the secretory cells such a small fraction of the population, and how does the diversity of secretory cell types arise? Using the mouse as our model organism, we find that secretory cells, and only secretory cells, pass through a phase of strong expression of the Notch ligand Delta1 (Dll1. Onset of this Dll1 expression coincides with a block to further cell division and is followed in much less than a cell cycle time by expression of Neurog3--a marker of enteroendocrine fate--or Gfi1--a marker of goblet or Paneth cell fate. By conditional knock-out of Dll1, we confirm that Delta-Notch signaling controls secretory commitment through lateral inhibition. We infer that cells stop dividing as they become committed to a secretory fate, while their neighbors continue dividing, explaining the final excess of absorptive over secretory cells. Our data rule out schemes in which cells first become committed to be secretory, and then diversify through subsequent cell divisions. A simple mathematical model shows how, instead, Notch signaling may simultaneously govern the commitment to be secretory and the choice between alternative modes of secretory differentiation.

  7. Delta Electroproduction in 12-C

    Energy Technology Data Exchange (ETDEWEB)

    McLauchlan, Steven [Univ. of Glasgow, Scotland (United Kingdom)

    2003-01-01

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

  8. Delta: Data Reduction for Integrated Application Workflows.

    Energy Technology Data Exchange (ETDEWEB)

    Lofstead, Gerald Fredrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jean-Baptiste, Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Oldfield, Ron A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-06-01

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

  9. Doubly truncated FosB isoform (Delta2DeltaFosB) induces osteosclerosis in transgenic mice and modulates expression and phosphorylation of Smads in osteoblasts independent of intrinsic AP-1 activity

    DEFF Research Database (Denmark)

    Sabatakos, George; Rowe, Glenn C; Kveiborg, Marie

    2008-01-01

    INTRODUCTION: Activator protein (AP)-1 family members play important roles in the development and maintenance of the adult skeleton. Transgenic mice that overexpress the naturally occurring DeltaFosB splice variant of FosB develop severe osteosclerosis. Translation of Deltafosb mRNA produces both...... DeltaFosB and a further truncated isoform (Delta2DeltaFosB) that lacks known transactivation domains but, like DeltaFosB, induces increased expression of osteoblast marker genes. MATERIALS AND METHODS: To test Delta2DeltaFosB's ability to induce bone formation in vivo, we generated transgenic mice...... that overexpress only Delta2DeltaFosB using the enolase 2 (ENO2) promoter-driven bitransgenic Tet-Off system. RESULTS: Despite Delta2DeltaFosB's failure to induce transcription of an AP-1 reporter gene, the transgenic mice exhibited both the bone and the fat phenotypes seen in the ENO2-DeltaFosB mice. Both Delta...

  10. Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA

    Science.gov (United States)

    Barnhardt, W.A.; Sherrod, B.L.

    2006-01-01

    Episodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar (GPR) and vibracores were used to investigate the morphologic and stratigraphic evolution of the Nisqually River delta. Two fluvial–deltaic facies are recognized on the basis of GPR data and sedimentary characteristics in cores, which suggest partial emplacement from sediment-rich floods that originated on Mount Rainier. Facies S consists of stacked, sheet-like deposits of andesitic sand up to 4 m thick that are continuous across the entire width of the delta. Flat-lying, highly reflective surfaces separate the sand sheets and comprise important facies boundaries. Beds of massive, pumice- and charcoal-rich sand overlie one of the buried surfaces. Organic-rich material from that surface, beneath the massive sand, yielded a radiocarbon age that is time-correlative with a series of known eruptive events that generated lahars in the upper Nisqually River valley. Facies CF consists of linear sandbodies or palaeochannels incised into facies S on the lower delta plain. Radiocarbon ages of wood fragments in the sandy channel-fill deposits also correlate in time to lahar deposits in upstream areas. Intrusive, sand-filled dikes and sills indicate liquefaction caused by post-depositional ground shaking related to earthquakes. Continued progradation of the delta into Puget Sound is currently balanced by tidal-current reworking, which redistributes sediment into large fields of ebb- and flood-oriented bedforms.

  11. International Year of Deltas 2013: A proposal

    Science.gov (United States)

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

    2011-10-01

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

  12. Size stratification in a Gilbert delta due to a varying base level: flume experiments.

    Science.gov (United States)

    Chavarrias, Victor; Orru, Clara; Viparelli, Enrica; Vide, Juan Pedro Martin; Blom, Astrid

    2014-05-01

    A foreset-dominated Gilbert delta is a delta that is dominated by sediment avalanches (i.e., discontinuous grain flows) over its front. It forms when a river flows into a basin or sea characterized by a flow depth that is much larger than the one in the fluvial reach, and the conditions are such that the transported sediment passing the brinkpoint forms a wedge at the topmost part of the foreset, which results in avalanches down the foreset and a fining upward pattern within the foreset deposit. A Gilbert delta is typically described in terms of a low-slope topset (resulting from deposition over the fluvial reach), a steep-slope foreset (resulting from sediment avalanches over the lee face), and a bottomset (resulting from deposition of fine sediment passing the brinkpoint as suspended load). The objective of the present study is to gain insight into the mechanisms taking part in Gilbert delta formation and progradation under variable base level conditions. In order to do so, three flume experiments were conducted in which the water discharge and sediment feed rate were maintained constant but the base level varied between the experiments: (I) constant base level, (II) a gradually rising base level, and (III) a slowly varying base level. The stratigraphy within the delta deposit was measured using image analysis combined with particle coloring. A steady base level resulted in aggradation over the fluvial reach in order to maintain a slope required to transport the supplied sediment downstream. Sea level rise enhanced the amount of aggradation over the fluvial reach due to the presence of an M1 backwater curve. The aggrading flux to the substrate was slightly coarser than the fed sediment. The sediment at the base of the foreset deposit appeared to become coarser in streamwise direction. Eventually, a fall of the base level induced an M2 backwater curve over the fluvial reach that caused degradation of the fluvial reach. Base level fall first induced erosion of the

  13. Sigma-delta cellular neural network for 2D modulation.

    Science.gov (United States)

    Aomori, Hisashi; Otake, Tsuyoshi; Takahashi, Nobuaki; Tanaka, Mamoru

    2008-01-01

    Although sigma-delta modulation is widely used for analog-to-digital (A/D) converters, sigma-delta concepts are only for 1D signals. Signal processing in the digital domain is extremely useful for 2D signals such as used in image processing, medical imaging, ultrasound imaging, and so on. The intricate task that provides true 2D sigma-delta modulation is feasible in the spatial domain sigma-delta modulation using the discrete-time cellular neural network (DT-CNN) with a C-template. In the proposed architecture, the A-template is used for a digital-to-analog converter (DAC), the C-template works as an integrator, and the nonlinear output function is used for the bilevel output. In addition, due to the cellular neural network (CNN) characteristics, each pixel of an image corresponds to a cell of a CNN, and each cell is connected spatially by the A-template. Therefore, the proposed system can be thought of as a very large-scale and super-parallel sigma-delta modulator. Moreover, the spatio-temporal dynamics is designed to obtain an optimal reconstruction signal. The experimental results show the excellent reconstruction performance and capabilities of the CNN as a sigma-delta modulator.

  14. The Selenga River delta - a geochemical barrier for the waters of Lake Baikal

    Science.gov (United States)

    Chalov, Sergey; Thorslund, Josefin; Pietron, Jan; Jarsjö, Jerker

    2016-04-01

    Delta systems play an important role in retention of sediments and contaminants to downstream recipients, through processes such as gravitational sedimentation, flocculation and biofiltration. The Selenga river delta is one of the world's largest inland deltas, providing a huge buffer zone between Lake Baikal and upstream waters of the Selenga river basin. Understanding the delta functioning is critical for the planning of water management measures in the Selenga River Basin and for protection of the waters of Lake Baikal. We here study the current state and functioning of the delta's ecosystem and hydrogeochemical processes. More specifically, we considered spatio-temporal changes in water flow, morphology and transport of sediments and metals within the delta and what potential impacts these changes may have on the delta functions. Results show that the delta network has a large influence on the mass of metals reaching the Lake Baikal at the delta outlet. Regions with high density of wetlands and small channels, in contrast to main channel regions, show a consistent pattern of considerable contaminant filtering and removal (between 77-99% for key metals), during both high and low flow conditions, following with a significant increase (2-3 times) of bottom sediment pollution. Geomorphological processes also governs the barrier function of the delta, due to partitioning of flow between different channel systems. These results are particularly relevant in the light of recent and expected future changes involving both the hydrology and water quality in the Lake Baikal basin. Taken together, this emphasizes the importance of understanding the interface between flow partitioning, delta morphology, and sediment and metal patterns and storage rates for fully capturing and quantifying the variety in delta functions. This is particularly relevant coupled to hydroclimatic changes in the region, which could lead to significant decline in barrier functions of the delta due to

  15. Stepwise morphological evolution of the active Yellow River (Huanghe) delta lobe (1976-2013): Dominant roles of riverine discharge and sediment grain size

    Science.gov (United States)

    Wu, Xiao; Bi, Naishuang; Xu, Jingping; Nittrouer, Jeffrey A.; Yang, Zuosheng; Saito, Yoshiki; Wang, Houjie

    2017-09-01

    The presently active Yellow River (Huanghe) delta lobe has been formed since 1976 when the river was artificially diverted. The process and driving forces of morphological evolution of the present delta lobe still remain unclear. Here we examined the stepwise morphological evolution of the active Yellow River delta lobe including both the subaerial and the subaqueous components, and illustrated the critical roles of riverine discharge and sediment grain size in dominating the deltaic evolution. The critical sediment loads for maintaining the delta stability were also calculated from water discharge and sediment load measured at station Lijin, the last gauging station approximately 100 km upstream from the river mouth. The results indicated that the development of active delta lobe including both subaerial and subaqueous components has experienced four sequential stages. During the first stage (1976-1981) after the channel migration, the unchannelized river flow enhanced deposition within the channel and floodplain between Lijin station and the river mouth. Therefore, the critical sediment supply calculated by the river inputs obtained from station Lijin was the highest. However, the actual sediment load at this stage (0.84 Gt/yr) was more than twice of the critical sediment load ( 0.35 Gt/yr) for sustaining the active subaerial area, which favored a rapid seaward progradation of the Yellow River subaerial delta. During the second stage (1981-1996), the engineering-facilitated channelized river flow and the increase in median grain size of suspended sediment delivered to the sea resulted in the critical sediment load for keeping the delta stability deceasing to 0.29 Gt/yr. The active delta lobe still gradually prograded seaward at an accretion rate of 11.9 km2/yr at this stage as the annual sediment load at Lijin station was 0.55 Gt/yr. From 1996 to 2002, the critical sediment load further decreased to 0.15 Gt/yr with the sediment grain size increased to 22.5

  16. Delta smelt: Life history and decline of a once abundant species in the San Francisco Estuary

    Science.gov (United States)

    Moyle, Peter B.; Brown, Larry R.; Durand, John R; Hobbs, James A.

    2016-01-01

    This paper reviews what has been learned about Delta Smelt and its status since the publication of The State of Bay-Delta Science, 2008 (Healey et al. 2008). The Delta Smelt is endemic to the upper San Francisco Estuary. Much of its historic habitat is no longer available and remaining habitat is increasingly unable to sustain the population. As a listed species living in the central node of California’s water supply system, Delta Smelt has been the focus of a large research effort to understand causes of decline and identify ways to recover the species. Since 2008, a remarkable record of innovative research on Delta Smelt has been achieved, which is summarized here. Unfortunately, research has not prevented the smelt’s continued decline, which is the result of multiple, interacting factors. A major driver of decline is change to the Delta ecosystem from water exports, resulting in reduced outflows and high levels of entrainment in the large pumps of the South Delta. Invasions of alien species, encouraged by environmental change, have also played a contributing role in the decline. Severe drought effects have pushed Delta Smelt to record low levels in 2014–2015. The rapid decline of the species and failure of recovery efforts demonstrate an inability to manage the Delta for the “co-equal goals” of maintaining a healthy ecosystem and providing a reliable water supply for Californians. Diverse and substantial management actions are needed to preserve Delta Smelt.

  17. Mammalian motoneuron axon targeting requires receptor protein tyrosine phosphatases sigma and delta.

    Science.gov (United States)

    Uetani, Noriko; Chagnon, Mélanie J; Kennedy, Timothy E; Iwakura, Yoichiro; Tremblay, Michel L

    2006-05-31

    The leukocyte common antigen-related (LAR) subfamily of receptor protein tyrosine phosphatases (RPTPs), LAR, RPTP-sigma, and RPTP-delta, regulate neuroendocrine development, axonal regeneration, and hippocampal long-term potentiation in mammals. In Drosophila, RPTPs are required for appropriate axon targeting during embryonic development. In contrast, deletion of any one of the three LAR-RPTP family members in mammals does not result in gross axon targeting defects. Both RPTP-sigma and RPTP-delta are highly expressed in the developing mammalian nervous system, suggesting they might be functionally redundant. To test this hypothesis, we generated RPTP-sigma and RPTP-delta (RPTP-sigma/delta) double-mutant mice. Although embryonic day 18.5 RPTP-sigma and RPTP-delta single-mutant embryos were viable, RPTP-sigma/delta double mutants were paralyzed, were never observed to draw a breath, and died shortly after cesarean section. RPTP-sigma/delta double mutants exhibit severe muscle dysgenesis and severe loss of motoneurons in the spinal cord. Detailed analysis of the projections of phrenic nerves in RPTP-sigma/delta double mutants indicated that these motoneuron axons emerge normally from the cervical spinal cord, but stall on reaching the diaphragm. Our results demonstrate that RPTP-sigma and RPTP-delta complement each other functionally during mammalian development, and reveal an essential contribution of RPTP-sigma and RPTP-delta to appropriate motoneuron axon targeting during mammalian axonogenesis.

  18. From stratigraphy to (inferred) processes: development of the late Pleistocene Po Delta clinothems at millennial to centennial scales

    Science.gov (United States)

    Pellegrini, Claudio; Asioli, Alessandra; Drexler, Tina; Bohacs, Kevin; Sweet, Michael; Maselli, Vittorio; Gamberi, Fabiano; Rovere, Marzia; Dalla Valle, Giacomo; Trincardi, Fabio

    2017-04-01

    The 350-m thick succession of the late-Pleistocene Po River Lowstand Delta (PRLD) deposited in just 17 k.y. encompassing the Last Glacial Maximum and contains stratal architecture at a physical scale commonly attributed to much longer time intervals, with complex, systematically varying internal clinothem characteristics. We document clinothem characteristics, stacking patterns, and controls through the integration of seismic-reflection data with sediment attributes, micropaleontology, regional climate, eustacy, and high-resolution age control on the PRLD. Within the PRLD, three clinothem types are characterized by distinctive topset geometry, shelf-edge and onlap-point trajectory, internal seismic facies, and interpreted bottomset deposits: Type A) moderate topset aggradation, ascending shelf-edge trajectories, and thin mass-transport bottomset deposits; Type B) eroded topset, descending shelf-edge trajectories, and bottomset distributary channel-lobe complexes; and Type C) maximal topset aggradation, ascending shelf-edge trajectories, and draped concordant bottomsets. Measured sediment accumulation rates suggest that Type A and C clinothems experienced reduced sediment bypass and delivery to the basin, whereas, Type B clinothems were associated with short intervals of increased sediment export from the shelf to deep water and development of distributary channel-lobe complexes. This interpretation is supported by micropaleontological analyses that highlight increased delivery of sediment and fresh water to the basin during the progradation of Type B clinothems, as suggested by the reduced occurrence of Cassidulina laevigata carinata and the peak abundance of Nonion spp. Each clinothem formed in a very short interval, from 0.4 to 4.7 k.y., contemporaneous with significant eustatic and climate changes. While changes in stacking patterns at these temporal scales have previously been observed in modern deltaic clinothems, the significance of our study is that we have

  19. Delta-Domain Predictive Control and Identification for Control

    DEFF Research Database (Denmark)

    Lauritsen, Morten Bach

    1997-01-01

    The present thesis is concerned with different aspects of modelling, control and identification of linear systems. Traditionally, discrete-time sampled-data systems are represented using shift-operator parametrizations. Such parametrizations are not suitable at fast sampling rates. An alternative...... parametrization using the so-called delta-operator is examined. It is shown how to maintain a close correspondence to continuous-time when sampling a system described in continuous-time by stochastic differential equations. Using delta-operator parametrizations makes it possible to unify discrete......-time and continuous-time theory. In addition these parametrizations possess certain numerical advantages compared to shift-operator representations. A new prediction method is developed. It is based on ideas from continuous-time but derived from discrete-time delta-operator models. It is shown to include the optimal...

  20. 2016 Rose Ojowhoh Delta State Polytechnic, Ozoro

    African Journals Online (AJOL)

    OJOHWOH ROSE

    ) 2016. Rose Ojowhoh. Delta State Polytechnic, Ozoro, Nigeria. Abstract. The study examined staff development and library services in academic libraries in Bayelsa and Delta States. Descriptive survey research design was used for this study, ...

  1. Delta Vegetation and Land Use [ds292

    Data.gov (United States)

    California Department of Resources — Vegetation and land use are mapped for the approximately 725,000 acres constituting the Legal Delta portion of the Sacramento and San Joaquin River Delta area....

  2. Nuclear receptor corepressor-dependent repression of peroxisome-proliferator-activated receptor delta-mediated transactivation

    DEFF Research Database (Denmark)

    Krogsdam, Anne-M; Nielsen, Curt A F; Neve, Søren

    2002-01-01

    delta-RXR alpha heterodimer bound to an acyl-CoA oxidase (ACO)-type peroxisome-proliferator response element recruited a glutathione S-transferase-NCoR fusion protein in a ligand-independent manner. Contrasting with most other nuclear receptors, PPAR delta was found to interact equally well......The nuclear receptor corepressor (NCoR) was isolated as a peroxisome-proliferator-activated receptor (PPAR) delta interacting protein using the yeast two-hybrid system. NCoR interacted strongly with the ligand-binding domain of PPAR delta, whereas interactions with the ligand-binding domains...

  3. Luminescence dating of delta sediments

    NARCIS (Netherlands)

    Chamberlain, Elizabeth L.; Wallinga, Jakob; Reimann, Tony; Goodbred, Steven L.; Steckler, Michael S.; Shen, Zhixiong; Sincavage, Ryan

    2017-01-01

    Deltas where luminescence dating is most essential due to organic-poor geologic records are also those where it is often most challenging due to unsuitable luminescence properties of quartz grains, associated with rapid production of young clastic sediment. One example is the

  4. Supersymmetry Transformations for Delta Potentials

    Directory of Open Access Journals (Sweden)

    David J. Fernández C.

    2011-03-01

    Full Text Available We make a detailed study of the first and second-order SUSY partners of a one-dimensional free Hamiltonian with a singular perturbation proportional to a Dirac delta function. It is shown that the second-order transformations increase the spectral manipulation possibilities offered by the standard first-order supersymmetric quantum mechanics.

  5. Construction and maintenance of the Ganges-Brahmaputra-Meghna delta: linking process, morphology, and stratigraphy.

    Science.gov (United States)

    Wilson, Carol A; Goodbred, Steven L

    2015-01-01

    We present a review of the processes, morphology, and stratigraphy of the Ganges-Brahmaputra-Meghna delta (GBMD), including insights gained from detailed elevation data. The review shows that the GBMD is best characterized as a composite system, with different regions having morphologic and stratigraphic attributes of an upland fluvial fan delta; a lowland, backwater-reach delta; a downdrift tidal delta plain; and an offshore subaqueous-delta clinoform. These distinct areas of upland and lowland fluvial reaches and tidal dominance vary in time and space, and we distinguish late-Holocene phases of delta construction, maintenance, and decline similar to delta-lobe cycling in other systems. The overall stability of the GBMD landform, relative to many deltas, reflects the efficient, widespread dispersal of sediment by the large monsoon discharge and high-energy tides that affect this region. However, we do identify portions of the delta that are in decline and losing elevation relative to sea level owing to insufficient sediment delivery. These areas, some of which are well inland of the coast, represent those most at risk to the continued effect of sea-level rise.

  6. Absolute $F_{\\sigma\\delta}$ spaces

    OpenAIRE

    Kovařík, Vojtěch; Kalenda, Ondřej

    2017-01-01

    We prove that hereditarily Lindel\\"of space which is $F_{\\sigma\\delta}$ in some compactification is absolutely $F_{\\sigma\\delta}$. In particular, this implies that any separable Banach space is absolutely $F_{\\sigma\\delta}$ when equipped with the weak topology.

  7. Process analysis of regional ozone formation over the Yangtze River Delta, China using the Community Multi-scale Air Quality modeling system

    Directory of Open Access Journals (Sweden)

    L. Li

    2012-11-01

    Full Text Available A high O3 episode was detected in urban Shanghai, a typical city in the Yangtze River Delta (YRD region in August 2010. The CMAQ integrated process rate method is applied to account for the contribution of different atmospheric processes during the high pollution episode. The analysis shows that the maximum concentration of ozone occurs due to transport phenomena, including vertical diffusion and horizontal advective transport. Gas-phase chemistry producing O3 mainly occurs at the height of 300–1500 m, causing a strong vertical O3 transport from upper levels to the surface layer. The gas-phase chemistry is an important sink for O3 in the surface layer, coupled with dry deposition. Cloud processes may contribute slightly to the increase of O3 due to convective clouds or to the decrease of O3 due to scavenging. The horizontal diffusion and heterogeneous chemistry contributions are negligible during the whole episode. Modeling results show that the O3 pollution characteristics among the different cities in the YRD region have both similarities and differences. During the buildup period, the O3 starts to appear in the city regions of the YRD and is then transported to the surrounding areas under the prevailing wind conditions. The O3 production from photochemical reaction in Shanghai and the surrounding area is most significant, due to the high emission intensity in the large city; this ozone is then transported out to sea by the westerly wind flow, and later diffuses to rural areas like Chongming island, Wuxi and even to Nanjing. The O3 concentrations start to decrease in the cities after sunset, due to titration of the NO emissions, but ozone can still be transported and maintain a significant concentration in rural areas and even regions outside the YRD region, where the NO emissions are very small.

  8. Process regime variability across growth faults in the Paleogene Lower Wilcox Guadalupe Delta, South Texas Gulf Coast

    Science.gov (United States)

    Olariu, Mariana I.; Ambrose, William A.

    2016-07-01

    The Wilcox Group in Texas is a 3000 m thick unit of clastic sediments deposited along the Gulf of Mexico coast during early Paleogene. This study integrates core facies analysis with subsurface well-log correlation to document the sedimentology and stratigraphy of the Lower Wilcox Guadalupe Delta. Core descriptions indicate a transition from wave- and tidally-influenced to wave-dominated deposition. Upward-coarsening facies successions contain current ripples, organic matter, low trace fossil abundance and low diversity, which suggest deposition in a fluvial prodelta to delta front environment. Heterolithic stratification with lenticular, wavy and flaser bedding indicate tidal influence. Pervasively bioturbated sandy mudstones and muddy sandstones with Cruziana ichnofacies and structureless sandstones with Ophiomorpha record deposition in wave-influenced deltas. Tidal channels truncate delta front deposits and display gradational upward-fining facies successions with basal lags and sandy tabular cross-beds passing into heterolithic tidal flats and biologically homogenized mudstones. Growth faults within the lower Wilcox control expanded thickness of sedimentary units (up to 4 times) on the downdip sides of faults. Increased local accommodation due to fault subsidence favors a stronger wave regime on the outer shelf due to unrestricted fetch and water depth. As the shoreline advances during deltaic progradation, successively more sediment is deposited in the downthrown depocenters and reworked along shore by wave processes, resulting in a thick sedimentary unit characterized by repeated stacking of shoreface sequences. Thick and laterally continuous clean sandstone successions in the downthrown compartments represent attractive hydrocarbon reservoirs. As a consequence of the wave dominance and increased accommodation, thick (tens of meters) sandstone-bodies with increased homogeneity and vertical permeability within the stacked shoreface successions are created.

  9. An Over-View of Niger Delta Indigenous Religion | Tasie | Lwati: A ...

    African Journals Online (AJOL)

    This essay is an outline and interpretation of Niger Delta indigenous religion. It examines the structure of the indigenous religion and points out that as heterogeneous and diverse as the people of Niger Delta are, so also is the indigenous religion of the people. Thus, an ethnic group may emphasize a belief system or an ...

  10. Measuring bovine gamma delta T cell function at the site of Mycobacterium bovis infection

    Science.gov (United States)

    Bovine gamma delta T cells are amongst the first cells to accumulate at the site of Mycobacterium bovis infection; however, their role in the developing lesion remains unclear. We utilized transcriptomics analysis, in situ hybridization, and a macrophage/gamma delta T cell co-culture system to eluc...

  11. A global deltas typology of environmental stress and its relation to terrestrial hydrology

    Science.gov (United States)

    Tessler, Z. D.; Vorosmarty, C. J.; McDonald, K. C.; Schroeder, R.; Grossberg, M.; Gladkova, I.; Aizenman, H.

    2013-12-01

    River delta systems around the world are under varying degrees of environmental stress stemming from a variety of human impacts, both from upstream basin based activities and local impacts on the deltas themselves, as well as sea level rise. These stresses are known to affect rates of relative sea level rise by disrupting the delivery or deposition of sediment on the delta. We present a global database of several of these stresses, and investigate patterns of stress across delta systems. Several methods of aggregating the environmental stressors into an index score are also investigated. A statistical clustering analysis, which we refer to as a "global delta fingerprinting system", across the environmental stresses identifies systems under similar states of threat. Several deltas, including the Nile, are in unique clusters, while regional patterns are evident among deltas in Southeast Asia. These patterns are compared with observed surface inundation derived from SAR, NDVI from MODIS, river discharge estimates from the WBMplus numerical model, and ocean wave activity from WAVEWATCH III. Delta inundation sensitivity to river and coastal forcings are observed to vary with environmental stress and social indicators including population density and GDP.

  12. The Potential of Time Series Based Earth Observation for the Monitoring of Large River Deltas

    Science.gov (United States)

    Kuenzer, C.; Leinenkugel, P.; Huth, J.; Ottinger, M.; Renaud, F.; Foufoula-Georgiou, E.; Vo Khac, T.; Trinh Thi, L.; Dech, S.; Koch, P.; Le Tissier, M.

    2015-12-01

    Although river deltas only contribute 5% to the overall land surface, nearly six hundred million people live in these complex social-ecological environments, which combine a variety of appealing locational advantages. In many countries deltas provide the major national contribution to agricultural and industrial production. At the same time these already very dynamic environments are exposed to a variety of threats, including the disturbance and replacement of valuable ecosystems, increasing water, soil, and air pollution, human induced land subsidence, sea level rise, as well upstream developments impacting water and sediment supplies. A constant monitoring of delta systems is thus of utmost relevance for understanding past and current land surface change and anticipating possible future developments. We present the potential of Earth Observation based analyses and derived novel information products that can play a key role in this context. Along with the current trend of opening up numerous satellite data archives go increasing capabilities to explore big data. Whereas in past decades remote sensing data were analysed based on the spectral-reflectance-defined 'finger print' of individual surfaces, we mainly exploit the 'temporal fingerprints' of our land surface in novel pathways of data analyses at differing spatial-, and temporally-dense scales. Following our results on an Earth Observation based characterization of large deltas globally, we present in depth results from the Mekong Delta in Vietnam, the Yellow River Delta in China, the Niger Delta in Nigeria, as well as additional deltas, focussing on the assessment of river delta flood and inundation dynamics, river delta coastline dynamics, delta morphology dynamics including the quantification of erosion and accretion processes, river delta land use change and trends, as well as the monitoring of compliance to environmental regulations.

  13. How Many Ultra-Low Delta-v Near Earth Objects Remain Undiscovered? Implications for missions.

    Science.gov (United States)

    Elvis, Martin; Ranjan, Sukrit; Galache, Jose Luis; Murphy, Max

    2015-08-01

    The past decade has witnessed considerable growth of interest in missions to Near-Earth Objects (NEOs). NEOs are considered prime targets for manned and robotic missions, for both scientific objectives as well as in-situ resource utilization including harvesting of water for propellant and life support and mining of high-value elements for sale on Earth. Appropriate targets are crucial to such missions. Hence, ultra-low delta-v mission targets are strongly favored. Some mission architectures rely on the discovery of more ultra-low delta-v NEOs. In fact the approved and executed NEO missions have all targeted asteroids with ultra-low LEO to asteroid rendezvous delta-v delta-v, and how many remain to be discovered in various size ranges down to ~100m. We couple the NEOSSat-1 model (Greenstreet et al., 2012) to the NEO size distribution derived from the NEOWISE survey (Mainzer et al., 2011b) to compute an absolute NEO population model. We compare the Minor Planet Center (MPC) catalog of known NEOs to this NEO population model. We compute the delta-v from LEO to asteroid rendezvous orbits using a modified Shoemaker-Helin (S-H) formalism that empirically removes biases found comparing S-H with the results from NHATS. The median delta-v of the known NEOs is 7.3 km/s, the median delta-v predicted by our NEO model is 9.8 km/s, suggesting that undiscovered objects are biased to higher delta-v. The survey of delta-v 300 m. However, there are tens of thousands of objects with delta-v delta-v delta-v) mission targets is limited given current propulsion technology. Visiting the full range of NEO sub-types will likely require improved propulsion systems.

  14. Dynamic controls on shallow clinoform geometry: Mekong Delta, Vietnam

    Science.gov (United States)

    Eidam, E. F.; Nittrouer, C. A.; Ogston, A. S.; DeMaster, D. J.; Liu, J. P.; Nguyen, T. T.; Nguyen, T. N.

    2017-09-01

    Compound deltas, composed of a subaerial delta plain and subaqueous clinoform, are common termini of large rivers. The transition between clinoform topset and foreset, or subaqueous rollover point, is located at 25-40-m water depth for many large tide-dominated deltas; this depth is controlled by removal of sediment from the topset by waves, currents, and gravity flows. However, the Mekong Delta, which has been classified as a mixed-energy system, has a relatively shallow subaqueous rollover at 4-6-m depth. This study evaluates dynamical measurements and seabed cores collected in Sep 2014 and Mar 2015 to understand processes of sediment transfer across the subaqueous delta, and evaluate possible linkages to geometry. During the southwest rainy monsoon (Sep 2014), high river discharge, landward return flow under the river plume, and regional circulation patterns facilitated limited sediment flux to the topset and foreset, and promoted alongshore flux to the northeast. Net observed sediment fluxes in Sep 2014 were landward, however, consistent with hypotheses about seasonal storage on the topset. During the northeast rainy monsoon, low river discharge and wind-driven currents facilitated intense landward and southwestward fluxes of sediment. In both seasons, bed shear velocities frequently exceeded the 0.01-0.02 m/s threshold of motion for sand, even in the absence of strong wave energy. Most sediment transport occurred at water depths 4 cm/yr at <10 m depth, and 3-8 cm/yr at 10-20 m depth) and lowest on the bottomset beds. Physically laminated sediments transitioned into mottled sediments between the upper foreset and bottomset regions. Application of a simple wave-stress model to the Mekong and several other clinoforms illustrates that shallow systems are not necessarily energy-limited, and thus rollover depths cannot be predicted solely by bed-stress distributions. In systems like the subaqueous Mekong Delta, direction of transport may have a key impact on

  15. ThemeDelta: Dynamic Segmentations over Temporal Topic Models.

    Science.gov (United States)

    Gad, Samah; Javed, Waqas; Ghani, Sohaib; Elmqvist, Niklas; Ewing, Tom; Hampton, Keith N; Ramakrishnan, Naren

    2015-05-01

    We present ThemeDelta, a visual analytics system for extracting and visualizing temporal trends, clustering, and reorganization in time-indexed textual datasets. ThemeDelta is supported by a dynamic temporal segmentation algorithm that integrates with topic modeling algorithms to identify change points where significant shifts in topics occur. This algorithm detects not only the clustering and associations of keywords in a time period, but also their convergence into topics (groups of keywords) that may later diverge into new groups. The visual representation of ThemeDelta uses sinuous, variable-width lines to show this evolution on a timeline, utilizing color for categories, and line width for keyword strength. We demonstrate how interaction with ThemeDelta helps capture the rise and fall of topics by analyzing archives of historical newspapers, of U.S. presidential campaign speeches, and of social messages collected through iNeighbors, a web-based social website. ThemeDelta is evaluated using a qualitative expert user study involving three researchers from rhetoric and history using the historical newspapers corpus.

  16. Sinking deltas due to human activities

    Science.gov (United States)

    Syvitski, James P. M.; Kettner, Albert J.; Overeem, Irina; Hutton, Eric W. H.; Hannon, Mark T.; Brakenridge, G. Robert; Day, John; Vörösmarty, Charles; Saito, Yoshiki; Giosan, Liviu; Nicholls, Robert J.

    2009-10-01

    Many of the world's largest deltas are densely populated and heavily farmed. Yet many of their inhabitants are becoming increasingly vulnerable to flooding and conversions of their land to open ocean. The vulnerability is a result of sediment compaction from the removal of oil, gas and water from the delta's underlying sediments, the trapping of sediment in reservoirs upstream and floodplain engineering in combination with rising global sea level. Here we present an assessment of 33 deltas chosen to represent the world's deltas. We find that in the past decade, 85% of the deltas experienced severe flooding, resulting in the temporary submergence of 260,000 km2. We conservatively estimate that the delta surface area vulnerable to flooding could increase by 50% under the current projected values for sea-level rise in the twenty-first century. This figure could increase if the capture of sediment upstream persists and continues to prevent the growth and buffering of the deltas.

  17. CMOS sigma-delta converters practical design guide

    CERN Document Server

    De la Rosa, Jose M

    2013-01-01

    A comprehensive overview of Sigma-Delta Analog-to-Digital Converters (ADCs) and a practical guide to their design in nano-scale CMOS for optimal performance. This book presents a systematic and comprehensive compilation of sigma-delta converter operating principles, the new advances in architectures and circuits, design methodologies and practical considerations - going from system-level specifications to silicon integration, packaging and measurements, with emphasis on nanometer CMOS implementation. The book emphasizes practical design issues - from high-level behavioural modelling i

  18. Sliding mode control the delta-sigma modulation approach

    CERN Document Server

    Sira-Ramírez, Hebertt

    2015-01-01

    This monograph presents a novel method of sliding mode control for switch-regulated nonlinear systems. The Delta Sigma modulation approach allows one to implement a continuous control scheme using one or multiple, independent switches, thus effectively merging the available linear and nonlinear controller design techniques with sliding mode control.   Sliding Mode Control: The Delta-Sigma Modulation Approach, combines rigorous mathematical derivation of the unique features of Sliding Mode Control and Delta-Sigma modulation with numerous illustrative examples from diverse areas of engineering. In addition, engineering case studies demonstrate the applicability of the technique and the ease with which one can implement the exposed results. This book will appeal to researchers in control engineering and can be used as graduate-level textbook for a first course on sliding mode control.

  19. about the Dirac Delta Function(?)

    Indian Academy of Sciences (India)

    one do in the case of a point charge q located at some point ro = (xo, Yo , zo)? A point charge is an idealiza- tion in which a finite amount of charge q is supposed to be packed into zero volume. The charge density must therefore be infinite at the point ro, and zero elsewhere. The delta function comes to our aid: we may write ...

  20. Late Quaternary depositional history of the Reuss delta, Switzerland: constraints from high-resolution seismic reflection and georadar surveys

    Science.gov (United States)

    Nitsche, Frank O.; Green, Alan G.; Horstmeyer, Heinrich; Büker, Frank

    2002-02-01

    Glacial erosion has caused overdeepening of many alpine valleys. After retreat of the ice, they were filled with heterogeneous deposits of glacial, lacustrine and fluvial sediments. A typical example of such a valley segment and its infill is the Reuss delta on the southern shore of Lake Lucerne in Switzerland. To obtain a detailed three-dimensional image of this valley segment, the ETH Institute of Geophysics has acquired several two-dimensional, high-resolution seismic and georadar profiles, and conducted a three-dimensional georadar survey. Interpretations of these geophysical data were constrained by a geological core extracted from a borehole 300 m deep near the investigation site. The seismic profiles imaged ca. 600 m of sediment infill above bedrock. Based on their reflection characteristics, five different deposition units were distinguished. These units were interpreted as a succession of clay/silt at the base, followed by different sand units with variable but generally increasing amounts of gravel. This succession represented a prograding delta that filled the southern part of Lake Lucerne. The latest fluvial development of the region is best represented by the georadar data. In particular, the three-dimensional georadar data set provides a detailed view of an ancient braided river channel

  1. Water quality in the Okavango Delta | Mmualefe | Water SA

    African Journals Online (AJOL)

    The Okavango Delta ecosystem sustains a large number of plant and animal species as well as providing resources for the livelihood of the riparian human population. Despite changes in flow patterns, rainfall and other climatic conditions over the past decades, the system has responded well to maintain low salt-water ...

  2. Inventory Management in Delta Allied Wire Industries Limited Asaba ...

    African Journals Online (AJOL)

    A good inventory system reduces production cost and consequently increases profit. Optimum management of inventory in the Delta – Allied Wire Industries Limited was studied in this research. The information needed was obtained through questionnaire and interviews of key staff of the company. Data collated were ...

  3. precise delta extraction scheme for reprogramming of wireless

    African Journals Online (AJOL)

    eobe

    pattern of the Execution Link File (ELF) structure to extract delta from two distinct firmware (original and the structure to extract ... similar utilities referred in literature, shows an appreciable capacity to reduce energy consumption rate as well as on rate as well as ..... D. Cullar and K. Pister, “System architecture directions for.

  4. The Problem with the Delta Cost Project Database

    Science.gov (United States)

    Jaquette, Ozan; Parra, Edna

    2016-01-01

    The Integrated Postsecondary Education System (IPEDS) collects data on Title IV institutions. The Delta Cost Project (DCP) integrated data from multiple IPEDS survey components into a public-use longitudinal dataset. The DCP Database was the basis for dozens of journal articles and a series of influential policy reports. Unfortunately, a flaw in…

  5. Anxious apprehension increases coupling of delta and beta oscillations

    NARCIS (Netherlands)

    Knyazev, G.G.; Schutter, D.J.L.G.; Honk, E.J. van

    2006-01-01

    Recent findings showing that anxiety is associated with enhanced coupling of EEG rhythms imply higher information exchange between populations of neurons associated with different oscillatory systems. In this study, influence of uncertainty on alpha–delta anticorrelation and delta–beta coupling was

  6. Stable isotope deltas: Tiny, yet robust signatures in nature

    Science.gov (United States)

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

  7. Stable isotope deltas: tiny, yet robust signatures in nature.

    Science.gov (United States)

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y., E-mail: haiyanzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, S.H., E-mail: shzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Cheng, M. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Z.X. [Beijing Institute of Aeronautica1 Materials, Beijing 100095 (China)

    2010-01-15

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

  9. Migration in Deltas: An Integrated Analysis

    Science.gov (United States)

    Nicholls, Robert J.; Hutton, Craig W.; Lazar, Attila; Adger, W. Neil; Allan, Andrew; Arto, Inaki; Vincent, Katharine; Rahman, Munsur; Salehin, Mashfiqus; Sugata, Hazra; Ghosh, Tuhin; Codjoe, Sam; Appeaning-Addo, Kwasi

    2017-04-01

    Deltas and low-lying coastal regions have long been perceived as vulnerable to global sea-level rise, with the potential for mass displacement of exposed populations. The assumption of mass displacement of populations in deltas requires a comprehensive reassessment in the light of present and future migration in deltas, including the potential role of adaptation to influence these decisions. At present, deltas are subject to multiple drivers of environmental change and often have high population densities as they are accessible and productive ecosystems. Climate change, catchment management, subsidence and land cover change drive environmental change across all deltas. Populations in deltas are also highly mobile, with significant urbanization trends and the growth of large cities and mega-cities within or adjacent to deltas across Asia and Africa. Such migration is driven primarily by economic opportunity, yet environmental change in general, and climate change in particular, are likely to play an increasing direct and indirect role in future migration trends. The policy challenges centre on the role of migration within regional adaptation strategies to climate change; the protection of vulnerable populations; and the future of urban settlements within deltas. This paper reviews current knowledge on migration and adaptation to environmental change to discern specific issues pertinent to delta regions. It develops a new integrated methodology to assess present and future migration in deltas using the Volta delta in Ghana, Mahanadi delta in India and Ganges-Brahmaputra-Meghna delta across India and Bangladesh. The integrated method focuses on: biophysical changes and spatial distribution of vulnerability; demographic changes and migration decision-making using multiple methods and data; macro-economic trends and scenarios in the deltas; and the policies and governance structures that constrain and enable adaptation. The analysis is facilitated by a range of

  10. Process analysis and sensitivity study of regional ozone formation over the Pearl River Delta, China, during the PRIDE-PRD2004 campaign using the Community Multiscale Air Quality modeling system

    Directory of Open Access Journals (Sweden)

    X. Wang

    2010-05-01

    Full Text Available In this study, the Community Multiscale Air Quality (CMAQ modeling system is used to simulate the ozone (O3 episodes during the Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, China, in October 2004 (PRIDE-PRD2004. The simulation suggests that O3 pollution is a regional phenomenon in the Pearl River Delta (PRD. Elevated O3 levels often occurred in the southwestern inland PRD, Pearl River estuary (PRE, and southern coastal areas during the 1-month field campaign. Three evolution patterns of simulated surface O3 are summarized based on different near-ground flow conditions. More than 75% of days featured interactions between weak synoptic forcing and local sea-land circulation. Integrated process rate (IPR analysis shows that photochemical production is a dominant contributor to O3 enhancement from 09:00 to 15:00 local standard time in the atmospheric boundary layer over most areas with elevated O3 occurrence in the mid-afternoon. The simulated ozone production efficiency is 2–8 O3 molecules per NOx molecule oxidized in areas with high O3 chemical production. Precursors of O3 originating from different source regions in the central PRD are mixed during the course of transport to downwind rural areas during nighttime and early morning, where they then contribute to the daytime O3 photochemical production. The sea-land circulation plays an important role on the regional O3 formation and distribution over PRD. Sensitivity studies suggest that O3 formation is volatile-organic-compound-limited in the central inland PRD, PRE, and surrounding coastal areas with less chemical aging (NOx/NOy>0.6, but is NOx-limited in the rural southwestern PRD with aged air (NOx/NOy<0.3.

  11. Experimental evidence of a delta-shock in nonlinear chromatography.

    Science.gov (United States)

    Mazzotti, Marco; Tarafder, Abhijit; Cornel, Jeroen; Gritti, Fabrice; Guiochon, Georges

    2010-03-26

    We report about a new type of composition front in nonlinear chromatography that is called delta-shock, which has to be added to the family of classical transitions, i.e. simple waves, shocks and semi-shocks. Recently, the occurrence of delta-shocks in the case of mixed competitive-cooperative isotherms of the following type n(i) = H(i)c(i)/(1 - K1c1 + K2c2) (i = 1, 2), (with H2 > H1, where components 1 and 2 have anti-Langmuir and Langmuir adsorption behavior, respectively) was predicted theoretically and their behavior was analyzed in the frame of the equilibrium theory of chromatography. The delta-shock can be viewed as a growing traveling spike superimposed to the discontinuity separating the initial and the feed state, which propagates along the column at constant speed and constant rate of growth. In this work we complement these findings from an experimental point of view. The binary system consisting of phenetole (component 1) and 4-tert-butylphenol (component 2) in methanol-water (about 2:1, v/v) on a Zorbax 300StableBond-C18 column from Agilent has been shown, through a series of overloaded pulse experiments and of frontal analysis experiments with the pure compounds, to be subject to the competitive-cooperative isotherm of the type above, up to rather large concentrations. This system does exhibit a delta-shock when the operating conditions are chosen according to theory, namely when phenetole initially saturating the column is displaced by 4-tert-butylphenol, both at high concentrations (the minimum concentrations exhibiting a fully developed delta-shock in this series of experiments were c1 = 20 g/L and c2 = 75 g/L). The propagation of the delta-shock matches the theoretical predictions in terms of both the effect of concentration and the effect of column length. This is the first experimental observation ever of a delta-shock in chromatography. It is noteworthy that the proof of the occurrence of the delta-shock reported here has been obtained in both

  12. Salinity Impacts on Agriculture and Groundwater in Delta Regions

    Science.gov (United States)

    Clarke, D.; Salehin, M.; Jairuddin, M.; Saleh, A. F. M.; Rahman, M. M.; Parks, K. E.; Haque, M. A.; Lázár, A. N.; Payo, A.

    2015-12-01

    Delta regions are attractive for high intensity agriculture due to the availability of rich sedimentary soils and of fresh water. Many of the world's tropical deltas support high population densities which are reliant on irrigated agriculture. However environmental changes such as sea level rise, tidal inundation and reduced river flows have reduced the quantity and quality of water available for successful agriculture. Additionally, anthropogenic influences such as the over abstraction of ground water and the increased use of low quality water from river inlets has resulted in the accumulation of salts in the soils which diminishes crop productivity. Communities based in these regions are usually reliant on the same water for drinking and cooking because surface water is frequently contaminated by commercial and urban pollution. The expansion of shallow tube well systems for drinking water and agricultural use over the last few decades has resulted in mobilisation of salinity in the coastal and estuarine fringes. Sustainable development in delta regions is becoming constrained by water salinity. However salinity is often studied as an independent issue by specialists working in the fields of agriculture, community water supply and groundwater. The lack of interaction between these disciplines often results in corrective actions being applied to one sector without fully assessing the effects of these actions on other sectors. This paper describes a framework for indentifying the causes and impacts of salinity in delta regions based on the source-pathway-receptor framework. It uses examples and scenarios from the Ganges-Brahmaputra-Meghna delta in Bangladesh together with field measurements and observations made in vulnerable coastal communities. The paper demonstrates the importance of creating an holistic understanding of the development and management of water resources to reduce the impact of salinity in fresh water in delta regions.

  13. Estimating Natural Flows into the California's Sacramento - San Joaquin Delta

    Science.gov (United States)

    Huang, G.; Kadir, T.; Chung, F. I.

    2014-12-01

    Natural flows into the California's Sacramento - San Joaquin Delta under predevelopment vegetative conditions, if and when reconstructed, can serve as a useful guide to establish minimum stream flows, restoration targets, and a basis for assessing impacts of global warming in the Bay-Delta System. Daily simulations of natural Delta flows for the period 1922-2009 were obtained using precipitation-snowmelt-runoff models for the upper watersheds that are tributaries to the California's Central Valley, and then routing the water through the Central Valley floor area using a modified version of the California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM) for water years 1922 through 2009. Daily stream inflows from all major upper watersheds were simulated using 23 Soil Water Assessment Tool (SWAT) models. Historical precipitation and reference evapotranspiration data were extracted from the SIMETAW2 with the 4km gridded meteorological data. The Historical natural and riparian vegetation distributions were compiled from several pre-1900 historical vegetation maps of the Central Valley. Wetlands were dynamically simulated using interconnected lakes. Flows overtopping natural levees were simulated using flow rating curves. New estimates of potential evapotranspiration from different vegetative classes under natural conditions were also used. Sensitivity simulations demonstrate that evapotranspiration estimates, native vegetation distribution, surface-groundwater interaction parameters, extinction depth for groundwater uptake, and other physical processes play a key role in the magnitude and timing of upstream flows arriving at the Delta. Findings contradict a common misconception that the magnitude of inflows to the Delta under natural vegetative conditions is greater than those under the historical agricultural and urban land use development. The developed models also enable to study the impacts of global warming by modifying meteorological and

  14. Petroleum system of the Shelf Rift Basin, East China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, A.C.; Armentrout, J.M.; Prebish, M. [Mobil Oil Corp., Dallas, TX (United States)] [and others

    1996-12-31

    The Tertiary section of the Oujioang and Quiontang Depressions of the East China Sea Basin consists of at least eight rift-related depositional sequences identified seismically by regionally significant onlap and truncation surfaces. These sequences are calibrated by several wells including the Wenzhou 6-1-1 permitting extrapolation of petroleum system elements using seismic facies analysis. Gas and condensate correlated to non-marine source rocks and reservoired in sandstone at the Pinghu field to the north of the study area provides an known petroleum system analogue. In the Shelf Rift Basin, synrift high-amplitude parallel reflections within the graben axes correlate with coaly siltstone strata and are interpreted as coastal plain and possibly lacustrine facies with source rock potential. Synrift clinoform seismic facies prograding from the northwest footwall correlate with non-marine to marginal marine conglomerate, sandstone and siltstone, and are interpreted as possible delta or fan-delta facies with reservoir potential although porosity and permeability is low within the Wenzhou 6-1-1 well. Post-rift thermal sag sequences are characterized by parallel and relatively continuous seismic reflections and locally developed clinoform packages. These facies correlate with porous and permeable marine sandstone and siltstone. Shales of potential sealing capacity occur within marine flooding intervals of both the synrift and post-rift sequences. Traps consist of differentially rotated synrift fill, and post-rift inversion anticlines. Major exploration risk factors include migration from the synrift coaly source rocks to the post-rift porous and permeable sandstones, and seismic imaging and drilling problems associated with extensive Tertiary igneous intrusions.

  15. Petroleum system of the Shelf Rift Basin, East China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, A.C.; Armentrout, J.M.; Prebish, M. (Mobil Oil Corp., Dallas, TX (United States)) (and others)

    1996-01-01

    The Tertiary section of the Oujioang and Quiontang Depressions of the East China Sea Basin consists of at least eight rift-related depositional sequences identified seismically by regionally significant onlap and truncation surfaces. These sequences are calibrated by several wells including the Wenzhou 6-1-1 permitting extrapolation of petroleum system elements using seismic facies analysis. Gas and condensate correlated to non-marine source rocks and reservoired in sandstone at the Pinghu field to the north of the study area provides an known petroleum system analogue. In the Shelf Rift Basin, synrift high-amplitude parallel reflections within the graben axes correlate with coaly siltstone strata and are interpreted as coastal plain and possibly lacustrine facies with source rock potential. Synrift clinoform seismic facies prograding from the northwest footwall correlate with non-marine to marginal marine conglomerate, sandstone and siltstone, and are interpreted as possible delta or fan-delta facies with reservoir potential although porosity and permeability is low within the Wenzhou 6-1-1 well. Post-rift thermal sag sequences are characterized by parallel and relatively continuous seismic reflections and locally developed clinoform packages. These facies correlate with porous and permeable marine sandstone and siltstone. Shales of potential sealing capacity occur within marine flooding intervals of both the synrift and post-rift sequences. Traps consist of differentially rotated synrift fill, and post-rift inversion anticlines. Major exploration risk factors include migration from the synrift coaly source rocks to the post-rift porous and permeable sandstones, and seismic imaging and drilling problems associated with extensive Tertiary igneous intrusions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Tina; Ke, Ying; Ly, Kevin [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand); McDonald, Fiona J., E-mail: fiona.mcdonald@otago.ac.nz [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand)

    2011-08-05

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

  17. Medición de la concentración de sedimentos en suspensión mediante dispositivos ópticos y acústicos: aplicación en sistemas tropicales (Delta del río Mira, Colombia Measurement of suspended sediment concentration using optical and acoustic devices: application in tropical systems (Mira River Delta, Colombia

    Directory of Open Access Journals (Sweden)

    Juan Camilo Restrepo

    2012-03-01

    and OBS-3A were used to measure SSC in the Mira River delta system (Morro Island and principal river mouth, located on the Pacific coast of Colombia, a coastal tropical environment where some oceanographic and estuarine factors determine the signal response of the instruments.

  18. Modeling tools for an Integrated River-Delta-Sea system investigation: the Pan-European Research Infrastructure DANUBIUS-RI philosophy

    Science.gov (United States)

    Umgiesser, Georg; Bellafiore, Debora; De Pascalis, Francesca; Icke, Joost; Stanica, Adrian

    2017-04-01

    The DANUBIUS Research Infrastructure (DANUBIUS-RI) is a new initiative to address the challenges and opportunities of research on large river- sea (RS) systems. DANUBIUS-RI is a distributed pan-European RI that will provide a platform for interdisciplinary research. It will deal with RS investigation through facilities and expertise from a large number of European institutions becoming a 'one-stop shop' for knowledge exchange in managing RS systems, ranging from freshwater to marine research. Globally, RS systems are complex and dynamic, with huge environmental, social and economic value. They are poorly understood but under increasing pressure through pollution, hydraulic engineering, water supply, energy, flood control and erosion. RS systems in Europe are among the most impacted globally, after centuries of industrialisation, urbanisation and agricultural intensification. Improved understanding is essential to avoid irreversible degradation and for restoration. DANUBIUS-RI will provide, among a number of other facilities concerning observations, analyses, impacts' evaluation, a modeling node that will provide integrated up-to-date tools, at locations of high scientific importance and opportunity, covering the RS systems - from source (upper parts of rivers - mountain lakes) to the transition with coastal seas. Modeling will be one of the major services provided by DANUBIUS-RI, relying on the inputs from the whole RI. RS systems are challenging from a modelling point of view, because of the complex morphology and the wide temporal and spatial range of processes occurring. Scale interaction plays a central role, considering the different hydro-eco-morphological processes on the large (basin) and small (local, coast, rivers, lagoons) scale. Currently, different model applications are made for the different geographical domains, and also for subsets of the processes. For instance there are separate models for rainfall runoff in the catchment, a sewer model for the

  19. The Niger Delta Amnesty Program

    Directory of Open Access Journals (Sweden)

    Benjamin A. Okonofua

    2016-06-01

    Full Text Available The armed conflict between militias and government forces in Nigeria’s Niger Delta region has spanned for more than two decades, defying all solutions. A disarmament, demobilization, and reintegration (DDR program was established in August 2015 in effort to end the violence and has remained in place. It is a radically different approach from past approaches that displayed zero tolerance to all political challenges to oil production or the allocation of oil profits. The approach appeared to be immediately successful in that it forced a ceasefire, engaged militants in planned programs to rehabilitate and reintegrate them into civilian society, and opened up the oil wells (many of which had been shut due to the crisis with the effect of increasing government revenue, which depends 85% on oil exports. Yet, few studies have attempted to understand the dynamics within the country that are responsible for the design and implementation of this broad policy shift or to understand whether and how the current initiative is able to end the conflict and institute peace beyond the short term. This study, therefore, is important because it provides a critical perspective that anticipates and explains emerging issues with the Niger Delta Amnesty Program, which have implications for DDR adaptation and implementation all over the world. Ultimately, the research demonstrates how the DDR program both transforms the Niger Delta conflict and becomes embroiled in intense contestations not only about the mechanism for transforming the targeted population but also whether and how the program incorporates women who are being deprioritized by the program.

  20. $\\Delta(1232)$-Resonance in the Hydrogen Spectrum

    OpenAIRE

    Hagelstein, Franziska

    2018-01-01

    The electromagnetic excitation of the $\\Delta(1232)$-resonance plays an appreciable role in the Lamb shift and hyperfine structure of muonic and electronic hydrogen. Its effect appears at the subleading order $\\mathcal{O}(\\alpha^5)$, together with other proton-polarizability contributions from forward two-photon exchange. We use the large-$N_c$ relations for the nucleon-to-delta transition form factors to compute the effect of the $\\Delta(1232)$ in the hydrogen spectrum. We pay particular att...

  1. Delta FosB regulates wheel running.

    Science.gov (United States)

    Werme, Martin; Messer, Chad; Olson, Lars; Gilden, Lauren; Thorén, Peter; Nestler, Eric J; Brené, Stefan

    2002-09-15

    DeltaFosB is a transcription factor that accumulates in a region-specific manner in the brain after chronic perturbations. For example, repeated administration of drugs of abuse increases levels of DeltaFosB in the striatum. In the present study, we analyzed the effect of spontaneous wheel running, as a model for a natural rewarding behavior, on levels of DeltaFosB in striatal regions. Moreover, mice that inducibly overexpress DeltaFosB in specific subpopulations of striatal neurons were used to study the possible role of DeltaFosB on running behavior. Lewis rats given ad libitum access to running wheels for 30 d covered what would correspond to approximately 10 km/d and showed increased levels of DeltaFosB in the nucleus accumbens compared with rats exposed to locked running wheels. Mice that overexpress DeltaFosB selectively in striatal dynorphin-containing neurons increased their daily running compared with control littermates, whereas mice that overexpress DeltaFosB predominantly in striatal enkephalin-containing neurons ran considerably less than controls. Data from the present study demonstrate that like drugs of abuse, voluntary running increases levels of DeltaFosB in brain reward pathways. Furthermore, overexpression of DeltaFosB in a distinct striatal output neuronal population increases running behavior. Because previous work has shown that DeltaFosB overexpression within this same neuronal population increases the rewarding properties of drugs of abuse, results of the present study suggest that DeltaFosB may play a key role in controlling both natural and drug-induced reward.

  2. Predicting Dynamic Coastal Delta Change in Response to Sea-Level Rise

    Directory of Open Access Journals (Sweden)

    Wietse I. Van De Lageweg

    2017-06-01

    Full Text Available The world’s largest deltas are densely populated, of significant economic importance and among the most valuable coastal ecosystems. Projected twenty-first century sea-level rise (SLR poses a threat to these low-lying coastal environments with inhabitants, resources and ecology becoming increasingly vulnerable to flooding. Large spatial differences exist in the parameters shaping the world’s deltas with respect to river discharge, tides and waves, substrate and sediment cohesion, sea-level rise, and human engineering. Here, we use a numerical flow and transport model to: (1 quantify the capability of different types of deltas to dynamically respond to SLR; and (2 evaluate the resultant coastal impact by assessing delta flooding, shoreline recession and coastal habitat changes. We show three different delta forcing experiments representative of many natural deltas: (1 river flow only; (2 river flow and waves; and (3 river flow and tides. We find that delta submergence, shoreline recession and changes in habitat are not dependent on the applied combination of river flow, waves and tides but are rather controlled by SLR. This implies that regional differences in SLR determine delta coastal impacts globally, potentially mitigated by sediment composition and ecosystem buffering. This process-based approach of modelling future deltaic change provides the first set of quantitative predictions of dynamic morphologic change for inclusion in Climate and Earth System Models while also informing local management of deltaic areas across the globe.

  3. El plan del delta - Holanda

    Directory of Open Access Journals (Sweden)

    Editorial, Equipo

    1963-09-01

    Full Text Available Holland is very poor in land resources. Hence its development has been directed towards intensive industrialization and maximum agricultural exploitation. The western part of the country is below sea level and is occupied by 65 percent of the population. Originally the coast consisted of a number of islands, estuaries and slight elevations. Man has transformed this coastline, first making a number of artificial lakes, or polders, and then converting these into fertile districts. These projects protect the soil by means of dykes, which require careful conservation, but even so violent floods are not infrequent. One of the difficult problems involved in this vast enterprise is the complex system of water supply, lines of communication and flow of the rivers into the sea along the estuary zone. This zone is on the south west, and to protect it a National Commission has been set up. After careful study, it was decided that the best defense against the violence of the sea would consist in closing off the inroads of the sea into the continental coastline. The set of hydraulic projects which constitutes this plan for the improvement of the sea defences will take 25 years to fulfil. The general project is highly ambitious and includes both maritime, road and structural works, in which there is a variety of stonework constructions. This paper describes, in brief outline, the main contents of the 11 headings into which the general construction project has been subdivided. In addition, this is supplemented with information on the projects which are already initiated and on the constructional procedure that is being adopted. Of these latter projects, the Nabla bridge is of particular interest. It is situated on the delta. It is made in prestressed concrete, and consists of 17 spans, of 60 length each. This enormous structure, in addition to its great length, and supporting a 22.8 ms wide roadway, is subjected to the tremendous forces 11» of the sea on one

  4. $\\Delta I=4$ and $\\Delta I=8$ bifurcations in rotational bands of diatomic molecules

    CERN Document Server

    Bonatsos, Dennis; Lalazissis, G A; Drenska, S B; Minkov, N; Raychev, P P; Roussev, R P; Bonatsos, Dennis

    1996-01-01

    It is shown that the recently observed $\\Delta I=4$ bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a $\\Delta I=8$ bifurcation, of the same order of magnitude as the $\\Delta I=4$ one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.

  5. A combined QC methodology in Ebro Delta HF radar system: real time web monitoring of diagnostic parameters and offline validation of current data

    Science.gov (United States)

    Lorente, Pablo; Piedracoba, Silvia; Soto-Navarro, Javier; Ruiz, Maria Isabel; Alvarez Fanjul, Enrique

    2015-04-01

    Over recent years, special attention has been focused on the development of protocols for near real-time quality control (QC) of HF radar derived current measurements. However, no agreement has been worldwide achieved to date to establish a standardized QC methodology, although a number of valuable international initiatives have been launched. In this context, Puertos del Estado (PdE) aims to implement a fully operational HF radar network with four different Codar SeaSonde HF radar systems by means of: - The development of a best-practices robust protocol for data processing and QC procedures to routinely monitor sites performance under a wide variety of ocean conditions. - The execution of validation works with in-situ observations to assess the accuracy of HF radar-derived current measurements. The main goal of the present work is to show this combined methodology for the specific case of Ebro HF radar (although easily expandable to the rest of PdE radar systems), deployed to manage Ebro River deltaic area and promote the conservation of an important aquatic ecosystem exposed to a severe erosion and reshape. To this aim, a web interface has been developed to efficiently monitor in real time the evolution of several diagnostic parameters provided by the manufacturer (CODAR) and used as indicators of HF radar system health. This web, updated automatically every hour, examines sites performance on different time basis in terms of: - Hardware parameters: power and temperature. - Radial parameters, among others: Signal-to-Noise Ratio (SNR), number of radial vectors provided by time step, maximum radial range and bearing. - Total uncertainty metrics provided by CODAR: zonal and meridional standard deviations and covariance between both components. - Additionally, a widget embedded in the web interface executes queries against PdE database, providing the chance to compare current time series observed by Tarragona buoy (located within Ebro HF radar spatial domain) and

  6. Controlling particle properties in {{YBa}}_{2}{{Cu}}_{3}{{\\rm{O}}}_{7-\\delta } nanocomposites by combining PLD with an inert gas condensation system

    Science.gov (United States)

    Sparing, M.; Reich, E.; Hänisch, J.; Gottschall, T.; Hühne, R.; Fähler, S.; Rellinghaus, B.; Schultz, L.; Holzapfel, B.

    2017-10-01

    The critical current density {J}{{c}} in {{YBa}}2{{Cu}}3{{{O}}}7-δ thin films, which limits their application in external magnetic fields, can be enhanced by the introduction of artificial pinning centers such as non-superconducting nanoparticles inducing additional defects and local strain in the superconducting matrix. To understand the correlation between superconductivity, defect structures and particles, a controlled integration of particles with adjustable properties is essential. A powerful technique for the growth of isolated nanoparticles in the range of 10 nm is dc-magnetron sputtering in an inert gas flow. The inert gas condensation (IGC) of particles allows for an independent control of both the particle diameter distribution and the areal density. We report on the integration of such gas-phase-condensed {{HfO}}2 nanoparticles into pulsed laser deposited (PLD) {{YBa}}2{{Cu}}3{{{O}}}7-δ thin film multilayers with a combined PLD-IGC system. The particles and the structure of the multilayers are analyzed by transmission electron microscopy on cross-sectional FIB lamellae. As a result of the IGC particle implementation, randomly as well as biaxially oriented {{BaHfO}}3 precipitates are formed in the {{YBa}}2{{Cu}}3{{{O}}}7-δ thin films. With as few as three interlayers of nanoparticles, the pinning force density is enhanced in the low-field region.

  7. Chemical and carbon isotopic evolution of hydrocarbons during prograde metamorphism from 100°C to 550°C: Case study in the Liassic black shale formation of Central Swiss Alps

    Science.gov (United States)

    Schwab, Valérie; Spangenberg, Jorge. E.; Grimalt, Joan O.

    2005-04-01

    Hydrocarbon distributions and stable isotope ratios of carbonates (δ 13C car, δ 18O car), kerogen (δ 13C ker), extractable organic matter (δ 13C EOM) and individual hydrocarbons of Liassic black shale samples from a prograde metamorphic sequence in the Swiss Alps were used to identify the major organic reactions with increasing metamorphic grade. The studied samples range from the diagenetic zone (17n-alkanes suggests the occurrence of cracking reactions of high molecular weight compounds. The isotopically heavier (up to 5.6 ‰) C 13n-alkanes with metamorphism suggests progressive thermal release of kerogen-linked fatty acid precursors and degradation of n-alkanes. Changes of the steroid and terpenoid distributions are clearly related to increasing metamorphic temperatures. The absence of 18α(H)-22,29,30-trisnorneohopane (Ts), the occurrence of 17β(H)-trisnorhopane, 17β(H), 21α(H)-hopanes in the C 29 to C 31 range and 5α(H),14α(H),17α(H)-20R C 27, C 29 steranes in the low diagenetic samples (bitumens. The higher thermal stress within the upper diagenetic zone (150°C) is marked by the presence of Ts, the disappearance of 17β(H)-trisnorhopane and thermodynamic equilibrium of the 22S/(22S + 22R) homohopane ratios. The increase of the ααα-sterane 20S/(20S + 20R) and 20R ββ/(ββ + αα) ratios (from 0.0 to 0.55 and from 0.0 to 0.40, respectively) in the upper diagenetic zone indicates the occurrence of isomerization reactions already at carbon isotopic compositions of n-alkanes related to metamorphism suggest that the organic geochemistry may help to evaluate the lowest grades of prograde metamorphism.

  8. U-Pb zircon geochronology and phase equilibria modelling of a mafic eclogite from the Sumdo complex of south-east Tibet: Insights into prograde zircon growth and the assembly of the Tibetan plateau

    Science.gov (United States)

    Weller, O. M.; St-Onge, M. R.; Rayner, N.; Waters, D. J.; Searle, M. P.; Palin, R. M.

    2016-10-01

    The Sumdo complex is a Permian-Triassic eclogitic metamorphic belt in south-east Tibet, which marks the location of a suture zone that separates the northern and southern Lhasa terranes. An integrated geochronological and petrological study of a mafic eclogite from the complex has constrained its tectonometamorphic history and provides a case study of zircon growth in eclogite as a product of prograde dissolution-precipitation. In situ U-Pb geochronology indicates that the eclogite contains a single population of zircon with a crystallisation age of 273.6 ± 2.8 Ma. The morphology and chemistry of the zircon grains are consistent with growth by dissolution-precipitation of protolith magmatic zircon. The presence of zircon grains as inclusions in the cores of peak phases indicates that zircon dissolution-precipitation occurred during prograde metamorphism, and calculated pressure and temperature conditions over which mineral inclusions in zircon are stable suggest that the zircon most likely precipitated at 15.5-16.5 kbar and 500-560 °C. Subsequent peak metamorphism is calculated to have reached pressure-temperature conditions of 27 ± 1 kbar and 670 ± 50 °C. Previous studies, which have documented a range of peak metamorphic conditions from high- to ultrahigh-pressure at c. 266-230 Ma, indicate that the Sumdo complex is a composite belt that experienced protracted eclogite exhumation. The results of this study are consistent with this interpretation, and extend the age range of high-pressure metamorphism in the complex to over 40 Myr. Analysis of published pressure-temperature-time data indicates two systematic behaviours within this spread. First, peak metamorphic temperatures declined over time. Second, eclogite exhumation occurred in two discrete intervals: soon after formation, and during the demise of the subduction zone. The latter behaviour serves as a reminder that eclogite exhumation is the exception rather than the rule.

  9. Electromagnetic excitation of the Delta(1232) resonance

    Energy Technology Data Exchange (ETDEWEB)

    V. Pascalutsa; M. Vanderhaeghen; Shin Nan Yang

    2006-09-05

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

  10. Tidal controls on river delta morphology

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

    2017-01-01

    River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world's largest deltas intensifies. Harbour development, construction of flood defences, sand mining and

  11. Floating City IJmeer : Accelerator for Delta Technology

    NARCIS (Netherlands)

    De Graaf, R.; Fremouw, M.; Van Bueren, B.; Czapiewska, K.; Kuijper, M.

    2006-01-01

    Climate change, sea level rise, population growth and ongoing urbanization result in higher vulnerability of the Rhine delta because it will result in increased flooding frequency, increasing investments and increased use of water, energy and other resources. The Rhine Delta also faces strong

  12. Characteristics of lead geochemistry and the mobility of Pb isotopes in the system of pedogenic rock-pedosphere-irrigated riverwater-cereal-atmosphere from the Yangtze River delta region, China.

    Science.gov (United States)

    Wang, Cheng; Wang, Jianhua; Yang, Zhongfang; Mao, Changping; Ji, Junfeng

    2013-11-01

    Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock-pedosphere-irrigated riverwater-cereal-atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of (208)Pb/(206)Pb=-1.157×(206)Pb/(207)Pb+3.46 (r(2)=0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb ((208)Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7-52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Kinematics and Application of a Hybrid Industrial Robot – Delta-RST

    Directory of Open Access Journals (Sweden)

    Ning Liu

    2014-04-01

    Full Text Available Serial robots and parallel robots have their own pros and cons. While hybrid robots consisting of both of them are possible and expected to retain their merits and minimize the disadvantages. The Delta-RST presented here is such a hybrid robot built up by integrating a 3-DoFs traditional Delta parallel structure and a 3-DoFs RST robotic wrist. In this paper, we focus on its kinematics analysis and its applications in industry. Firstly, the robotic system of the Delta-RST will be described briefly. Then the complete and systemic kinematics of this kind of robot will be presented in detail, followed by simulations and applications to demonstrate the correctness of the analysis, as well as the effectiveness of the developed robotic system. The closed-form kinematic analysis results are universal for similar hybrid robots constructing with the Delta parallel mechanism and serial chains.

  14. The {\\delta}N Formalism

    CERN Document Server

    Sugiyama, Naonori S; Futamase, Toshifumi

    2013-01-01

    Precise understanding of non-linear evolution of cosmological perturbations during inflation is necessary for the correct interpretation of measurements of non-Gaussian correlations in the cosmic microwave background and the large-scale structure of the universe. The "{\\delta}N formalism" is a popular and powerful technique for computing non-linear evolution of cosmological perturbations on large scales. In particular, it enables us to compute the curvature perturbation, {\\zeta}, on large scales without actually solving perturbed field equations. However, people often wonder why this is the case. In order for this approach to be valid, the perturbed Hamiltonian constraint and matter-field equations on large scales must, with a suitable choice of coordinates, take on the same forms as the corresponding unperturbed equations. We find that this is possible when (1) the unperturbed metric is given by a homogeneous and isotropic Friedmann-Lema\\^itre-Robertson-Walker metric; and (2) on large scales and with a suita...

  15. Delta connected resonant snubber circuit

    Science.gov (United States)

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

    1998-01-20

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

  16. Tidal controls on river delta morphology

    Science.gov (United States)

    Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

    2017-09-01

    River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

  17. Antidepressant-like effect of delta9-tetrahydrocannabinol and other cannabinoids isolated from Cannabis sativa L.

    Science.gov (United States)

    El-Alfy, Abir T; Ivey, Kelly; Robinson, Keisha; Ahmed, Safwat; Radwan, Mohamed; Slade, Desmond; Khan, Ikhlas; ElSohly, Mahmoud; Ross, Samir

    2010-06-01

    The antidepressant action of cannabis as well as the interaction between antidepressants and the endocannabinoid system has been reported. This study was conducted to assess the antidepressant-like activity of Delta(9)-THC and other cannabinoids. Cannabinoids were initially evaluated in the mouse tetrad assay to determine doses that do not induce hypothermia or catalepsy. The automated mouse forced swim (FST) and tail suspension (TST) tests were used to determine antidepressant action. At doses lacking hypothermic and cataleptic effects (1.25, 2.5, and 5 mg/kg, i.p.), both Delta(9)-THC and Delta(8)-THC showed a U-shaped dose response with only Delta(9)-THC showing significant antidepressant-like effects at 2.5 mg/kg (pcannabidiol (CBD) exhibited significant effect at 20 and 200mg/kg, respectively (p<0.01). The antidepressant-like action of Delta(9)-THC and CBC was further confirmed in the TST. Delta(9)-THC exhibited the same U-shaped dose response with significant antidepressant-like action at 2.5 mg/kg (p<0.05) while CBC resulted in a significant dose-dependent decrease in immobility at 40 and 80 mg/kg doses (p<0.01). Results of this study show that Delta(9)-THC and other cannabinoids exert antidepressant-like actions, and thus may contribute to the overall mood-elevating properties of cannabis. Published by Elsevier Inc.

  18. Integrated assessment of social and environmental sustainability dynamics in the Ganges-Brahmaputra-Meghna delta, Bangladesh

    Science.gov (United States)

    Nicholls, R. J.; Hutton, C. W.; Lázár, A. N.; Allan, A.; Adger, W. N.; Adams, H.; Wolf, J.; Rahman, M.; Salehin, M.

    2016-12-01

    Deltas provide diverse ecosystem services and benefits for their populations. At the same time, deltas are also recognised as one of the most vulnerable coastal environments, with a range of drivers operating at multiple scales, from global climate change and sea-level rise to deltaic-scale subsidence and land cover change. These drivers threaten these ecosystem services, which often provide livelihoods for the poorest communities in these regions. The imperative to maintain ecosystem services presents a development challenge: how to develop deltaic areas in ways that are sustainable and benefit all residents including the most vulnerable. Here we present an integrated framework to analyse changing ecosystem services in deltas and the implications for human well-being, focussing in particular on the provisioning ecosystem services of agriculture, inland and offshore capture fisheries, aquaculture and mangroves that directly support livelihoods. The framework is applied to the world's most populated delta, the Ganges-Brahmaputra-Meghna Delta within Bangladesh. The framework adopts a systemic perspective to represent the principal biophysical and socio-ecological components and their interaction. A range of methods are integrated within a quantitative framework, including biophysical and socio-economic modelling and analyses of governance through scenario development. The approach is iterative, with learning both within the project team and with national policy-making stakeholders. The analysis is used to explore physical and social outcomes for the delta under different scenarios and policy choices. We consider how the approach is transferable to other deltas and potentially other coastal areas.

  19. Identifying hazards associated with lava deltas

    Science.gov (United States)

    Poland, Michael P.; Orr, Tim R.

    2014-01-01

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

  20. Questionnaire discrimination: (re)-introducing coefficient delta.

    Science.gov (United States)

    Hankins, Matthew

    2007-05-18

    Questionnaires are used routinely in clinical research to measure health status and quality of life. Questionnaire measurements are traditionally formally assessed by indices of reliability (the degree of measurement error) and validity (the extent to which the questionnaire measures what it is supposed to measure). Neither of these indices assesses the degree to which the questionnaire is able to discriminate between individuals, an important aspect of measurement. This paper introduces and extends an existing index of a questionnaire's ability to distinguish between individuals, that is, the questionnaire's discrimination. Ferguson (1949) 1 derived an index of test discrimination, coefficient delta, for psychometric tests with dichotomous (correct/incorrect) items. In this paper a general form of the formula, deltaG, is derived for the more general class of questionnaires allowing for several response choices. The calculation and characteristics of deltaG are then demonstrated using questionnaire data (GHQ-12) from 2003-2004 British Household Panel Survey (N = 14761). Coefficients for reliability (alpha) and discrimination (deltaG) are computed for two commonly-used GHQ-12 coding methods: dichotomous coding and four-point Likert-type coding. Both scoring methods were reliable (alpha > 0.88). However, deltaG was substantially lower (0.73) for the dichotomous coding of the GHQ-12 than for the Likert-type method (deltaG = 0.96), indicating that the dichotomous coding, although reliable, failed to discriminate between individuals. Coefficient deltaG was shown to have decisive utility in distinguishing between the cross-sectional discrimination of two equally reliable scoring methods. Ferguson's delta has been neglected in discussions of questionnaire design and performance, perhaps because it has not been implemented in software and was restricted to questionnaires with dichotomous items, which are rare in health care research. It is suggested that the more general

  1. Living along the Limes : Landscape and settlement in the Lower Rhine Delta during Roman and Early Medieval times

    NARCIS (Netherlands)

    van Dinter, M.

    2017-01-01

    River environments have played a vital role in human history. However, the intensive exploitation of rivers and deltas has increasingly caused problems, particularly in lowland deltas. Solving the current problems also requires a more fundamental understanding of how natural and societal systems

  2. Rice market integration in the Mekong river delta : the successful liberalisation of the domestic food market in Vietnam

    NARCIS (Netherlands)

    Hai, Luu Thanh Duc; Lutz, Clemens; Praagman, Cornelis

    2004-01-01

    This article analyses the spatial price differences in the rice market of the Mekong River Delta to assess the impact of the liberalisation policies on its functioning. The results of these policies carried out during the last two decades are impressive. The rice market system in the Delta is

  3. Management options for restoring estuarine dynamics and implications for ecosystems: a quantitative approach for the Southwest Delta in the Netherlands

    NARCIS (Netherlands)

    Ysebaert, T.; van der Hoek, D.-J.; Wortelboer, R.; Wijsman, J.W.M.; Tangelder, M.; Nolte, A.

    2016-01-01

    The Delta Works, a series of dams and barriers constructed in the 1960's–1980's changed the estuarine landscape of the Rhine-Meuse-Scheldt delta (SW Netherlands) into more stagnant and disengaged freshwater, brackish water or saltwater lakes. The remaining tidal systems were adapted by building a

  4. The role of gamma/delta T cells in progesterone-mediated immunomodulation during pregnancy: a review.

    Science.gov (United States)

    Szekeres-Bartho, J; Barakonyi, A; Polgar, B; Par, G; Faust, Z; Palkovics, T; Szereday, L

    1999-07-01

    To determine if pregnancy is recognized by the immune system and if inadequate recognition of fetal antigens might result in failed pregnancy. Review of literature and current data. In the decidua gamma/delta TCR positive cells significantly increase in number. A subset of gamma/delta T cells reacts with nonpolymorphic Class I or Class I like molecules. Trophoblast recognition is mediated by the V gamma 1 subset which recognize a conserved mammalian sequence on the trophoblast. Almost all gamma/delta T cells in the decidua are activated and use the V delta 1 chain, whereas the majority of human peripheral gamma/delta lymphocytes expresses V gamma 9/V delta 2 TCR. Peripheral gamma/delta T cells of healthy pregnant women preferentially use V gamma V delta 1 chains, on the other hand, those of recurrent aborters use the V gamma 9V delta 2 combination. Signaling via the V gamma 1.4V delta 1 receptor induces a Th2 type response, whereas activation of the lymphocytes via the V gamma 9V delta 2 receptor results in increased IL-12 production and natural killer (NK) activity. In the presence of progesterone, activated lymphocytes synthesize the progesterone induced blocking factor (PIBF), which inhibits NK activity and exerts an anti abortive effect in vivo. Decidual CD56+ and gamma delta+ cells are to a high extent the same population. All decidual CD56+ cells express PIBF, thus it cannot be excluded that local production of this substance contributes to low decidual NK activity and thus to the success of the pregnancy.

  5. High-resolution IF-to-baseband sigma delta ADC for car radios

    CERN Document Server

    Silva, Paulo G R

    2008-01-01

    High-Resolution IF-to-Baseband SigmaDelta ADC for Car Radios addresses the theory, system level design and circuit implementation of a high-resolution continuous-time IF-to-baseband quadrature SigmaDelta ADC. The target application of this ADC is in AM/FM/IBOC car radios. The ADC achieves a dynamic range of 118dB, which eliminates the need for an IF VGA or AM channel filter in car radios.

  6. Experimental evidence of a delta-shock in nonlinear chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

    2010-01-01

    We report about a new type of composition front in nonlinear chromatography that is called delta-shock, which has to be added to the family of classical transitions, i.e. simple waves, shocks and semi-shocks. Recently, the occurrence of delta-shocks in the case of mixed competitive-cooperative isotherms of the following type n{sub i} = H{sub i}c{sub i}/1 = K{sub 1}c{sub 1} + K{sub 2}c{sub 2} (i = 1,2), (with H{sub 2} > H{sub 1}, where components 1 and 2 have anti-Langmuir and Langmuir adsorption behavior, respectively) was predicted theoretically and their behavior was analyzed in the frame of the equilibrium theory of chromatography. The delta-shock can be viewed as a growing traveling spike superimposed to the discontinuity separating the initial and the feed state, which propagates along the column at constant speed and constant rate of growth. In this work we complement these findings from an experimental point of view. The binary system consisting of phenetole (component 1) and 4-tert-butylphenol (component 2) in methanol-water (about 2:1, v/v) on a Zorbax 300StableBond-C18 column from Agilent has been shown, through a series of overloaded pulse experiments and of frontal analysis experiments with the pure compounds, to be subject to the competitive-cooperative isotherm of the type above, up to rather large concentrations. This system does exhibit adelta-shock when the operating conditions are chosen according to theory, namely when phenetole initially saturating the column is displaced by 4-tert-butylphenol, both at high concentrations (the minimum concentrations exhibiting a fully developed delta-shock in this series of experiments were c{sub 1} = 20 g/L and c{sub 2} = 75 g/L). The propagation of the delta-shock matches the theoretical predictions in terms of both the effect of concentration and the effect of column length. This is the first experimental observation ever of adelta-shock in chromatography. It is noteworthy that the proof of the occurrence of

  7. Sediment budgets, transport, and depositional trends in a large tidal delta

    Science.gov (United States)

    Morgan, Tara; Wright, Scott A.

    2016-01-01

    The Sacramento-San Joaquin Delta is the largest delta on the west coast of the United States. It is formed where the confluence of California’s two largest rivers (the Sacramento and San Joaquin) meet the ocean tides and has a significant physical gradient from fluvial to tidal. It is a semidiurnal system (two high and two low tides per day). Today, the Delta is one of the most manipulated in the United States. Once composed of many shallow, meandering and braided dendritic channels and dead-end sloughs and wetlands, it is now a network of leveed canals moving clear water around subsided islands. It historically has supported a biologically diverse tidal wetland complex, of which only 3% remains today (Whipple et al., 2012). It has also witnessed a collapse in the native fish populations. The Delta provides critical habitat for native species, however the hydrology and water quality are complicated by manipulations and diversions to satisfy multiple statewide objectives. Today water managers face co-equal goals of water supply to Californians and maintenance of ecosystem health and function. The Delta is a hub for both a multi-hundred-million dollar agricultural industry and a massive north-to-south water delivery system, supplying the primary source of freshwater to Central Valley farmers and drinking water for two-thirds of California’s population. Large pump facilities support the water demand and draw water from the Delta, further altering circulation patterns and redirecting the net flow toward the export facilities (Monsen et al., 2007). Fluvial sedimentation, along with organic accumulation, creates and sustains the Delta landscape. Hydraulic mining for gold in the watershed during the late 1800s delivered an especially large sediment pulse to the Delta. More recently, from 1955 to the present, a significant sediment decline has been observed that is thought to have been caused mostly by the construction of water storage reservoirs that trap the upstream

  8. Collaborative Innovation Research on High-tech Industry in the Center Delta

    Directory of Open Access Journals (Sweden)

    Yan Jingdong

    2017-01-01

    Full Text Available As a strong point in the Middle Rises Strategy, the Center Delta is of great significance to high-tech industry development. While the collaborative innovation is an effective way to promote the coordinated development of regional economy. This article selected electronic and communication equipment manufacturing industry of 3 provinces in the Center Delta as samples, built evaluation index system of collaborative innovation of high-tech industry, and put the relevant data into the system coordination degree model, in order to get the synergy of industrial innovation system and innovation environment system of 3 provinces. The empirical results shown that the industrial innovation system and innovation environment system coordination degree of Hubei province was the highest, while Jiangxi province was the lowest. Based on the empirical result analysis of the above-mentioned systems, this article put forward suggestions to promote the development of the high-tech industry collaborative innovation in the Center Delta.

  9. Economic Costs and Adaptations for Alternative Regulations of California's Sacramento–San Joaquin Delta

    Directory of Open Access Journals (Sweden)

    Stacy K. Tanaka

    2011-07-01

    Full Text Available Stacy K. Tanaka, Christina R. Connell–Buck, Kaveh Madani, Josue Medellín-Azuara, Jay R. Lund, and Ellen Hanakdoi: http://dx.doi.org/10.15447/sfews.2014v9iss2art4Water exports from California’s Sacramento–San Joaquin Delta are an environmental concern because they reduce net outflows of fresh water from the Delta, and can entrain fish and disrupt flows within the Delta. If exports were no longer pumped from within the Delta, the regulatory issue becomes one of maintaining appropriate flows into and out of the Delta. This paper presents the results of two sets of hydro-economic optimization modeling runs, which were developed to represent a range of modified Delta operations and their economic and operational effects on California’s water supply system. The first set of runs represents decreasing export capacity from the Delta. The second set increases minimum net Delta outflow (MNDO requirements. The hydro-economic model seeks the least–cost statewide water management scheme for water supply, including a wide range of resources and water management options. Results show that reducing exports or increasing MNDO requirements increase annual average statewide water scarcity, scarcity costs, and operating costs (from greater use of desalination, wastewater recycling, water treatment, and pumping. Effects of reduced exports are especially concentrated in agricultural communities in the southern Central Valley because of their loss of access to overall water supply exports and their ability to transfer remaining water to southern California. Increased outflow requirements increase water scarcity and associated costs throughout California. For an equivalent amount of average Delta outflows, statewide costs increase more rapidly when exports alone are reduced than when minimum outflow requirements are increased and effects are more widely distributed statewide.

  10. Adaptive Management Methods to Protect the California Sacramento-San Joaquin Delta Water Resource

    Science.gov (United States)

    Bubenheim, David

    2016-01-01

    The California Sacramento-San Joaquin River Delta is the hub for California's water supply, conveying water from Northern to Southern California agriculture and communities while supporting important ecosystem services, agriculture, and communities in the Delta. Changes in climate, long-term drought, water quality changes, and expansion of invasive aquatic plants threatens ecosystems, impedes ecosystem restoration, and is economically, environmentally, and sociologically detrimental to the San Francisco Bay/California Delta complex. NASA Ames Research Center and the USDA-ARS partnered with the State of California and local governments to develop science-based, adaptive-management strategies for the Sacramento-San Joaquin Delta. The project combines science, operations, and economics related to integrated management scenarios for aquatic weeds to help land and waterway managers make science-informed decisions regarding management and outcomes. The team provides a comprehensive understanding of agricultural and urban land use in the Delta and the major water sheds (San Joaquin/Sacramento) supplying the Delta and interaction with drought and climate impacts on the environment, water quality, and weed growth. The team recommends conservation and modified land-use practices and aids local Delta stakeholders in developing management strategies. New remote sensing tools have been developed to enhance ability to assess conditions, inform decision support tools, and monitor management practices. Science gaps in understanding how native and invasive plants respond to altered environmental conditions are being filled and provide critical biological response parameters for Delta-SWAT simulation modeling. Operational agencies such as the California Department of Boating and Waterways provide testing and act as initial adopter of decision support tools. Methods developed by the project can become routine land and water management tools in complex river delta systems.

  11. Developing Modern Niger Delta Formalism

    Directory of Open Access Journals (Sweden)

    Edewor Uyoyou Nelson O

    2014-11-01

    Full Text Available Edewor Nelson (b. 1970 is a sculptor whose works depict configurations that espouse contexts associated with inimical and exploitative tendencies of petroleum oil exploration and exploitation in the Niger Delta region. His expressions represent a new formalism that is iconic of the region’s reality in terms of environmental degradation and fundamental human rights abuses. This motivation became imperative in the seemingly failure of other artistic explorations on the subject to adequately reflect modern formal archetypes for which the region’s dilemma can be expressed. The challenge of analytic study of this effort for attaining interpretative insights into this studio practice is pertinent. To realize this, corresponding Ivri traditional art form associated with the past in the region has been studied alongside petroleum drilling–related forms. This provides the fulcrum on which this article approaches an analysis of contextual and conceptual applications attributable to the stylistic oeuvre of Edewor’s practice since 1997. It uses formalism and iconography interpretative tools for its critical discourse.

  12. Late Holocene Shoreline Dynamics and Sediment Partitioning in the Waipaoa Sedimentary System, New Zealand

    Science.gov (United States)

    Wolinsky, M. A.; Swenson, J. B.; Bever, A.; Harris, C. K.

    2006-12-01

    Over the course of the late Holocene highstand the shoreline at Poverty Bay has actively prograded due to sediment influx from the Waipaoa river. Mapping of paleo-shoreline positions has shown that the progradation rate has decreased through time. We use sedimentary process modeling on multiple time scales to evaluate potential causes of this decrease, and to constrain long-term sediment fluxes entering the coastal plain and exiting Poverty Bay. We consider three factors which could potentially contribute to the decelerating progradation: (1) Increasing basin width as the shoreline progrades seaward, (2) decreasing sediment supply to the shore due to upstream decreases in erosion or increases in storage, and (3) increasing sediment removal from the nearshore as the shoreline approaches the mouth of Poverty Bay and the coast becomes less sheltered from energetic waves. Simplified (1D diffusive) long-term stratigraphic modeling of the fluvial system is used to explore the effects of variations in upstream sediment and water supply on floodplain storage and shoreline progradation. We use a detailed 3D hydrodynamic model of sediment transport by waves and currents to explore the fate of sediment which reaches the shore. Results from these 3D simulations of single flood and storm events are scaled up to constrain the partitioning of sediment between the nearshore and outer shelf.

  13. Legal Delta Boundary, 2001, DWR [ds586

    Data.gov (United States)

    California Department of Resources — The original topographic maps containing the drawn delta border were scanned from the Department of Water Resources. Images were registered to 1:24,000 USGS DRG's in...

  14. Delta-nucleus dynamics: proceedings of symposium

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-10-01

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

  15. California Black Rail - Central Delta [ds17

    Data.gov (United States)

    California Department of Resources — Results of taped-call black rail surveys of in-stream habitat within certain waterways in the central Sacramento / San Joaquin Delta during 1992 and 1993. TIME...

  16. Yukon Delta NWR Land Status Maps

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a map of Yukon Delta National Wildlife Refuge within the State of Alaska. It depicts the refuge and wilderness boundaries, hillshaded topography, and...

  17. HDVDB: a data warehouse for hepatitis delta virus.

    Science.gov (United States)

    Singh, Sarita; Gupta, Sunil Kumar; Nischal, Anuradha; Pant, Kamlesh Kumar; Seth, Prahlad Kishore

    2015-01-01

    Hepatitis Delta Virus (HDV) is an RNA virus and causes delta hepatitis in humans. Although a lot of data is available for HDV, but retrieval of information is a complicated task. Current web database 'HDVDB' provides a comprehensive web-resource for HDV. The database is basically concerned with basic information about HDV and disease caused by this virus, genome structure, pathogenesis, epidemiology, symptoms and prevention, etc. Database also supplies sequence data and bibliographic information about HDV. A tool 'siHDV Predict' to design the effective siRNA molecule to control the activity of HDV, is also integrated in database. It is a user friendly information system available at public domain and provides annotated information about HDV for research scholars, scientists, pharma industry people for further study.

  18. On new physics in $\\Delta \\Gamma_d$

    CERN Document Server

    Bobeth, Christoph; Lenz, Alexander; Pecjak, Ben; Tetlalmatzi-Xolocotzi, Gilberto

    2014-01-01

    Motivated by the recent measurement of the dimuon asymmetry by the D{\\O} collaboration, which could be interpreted as an enhanced decay rate difference in the neutral $B_d$-meson system, we investigate the possible size of new-physics contributions to $\\Delta \\Gamma_d$. In particular, we perform model-independent studies of non-standard effects associated to the dimension-six current-current operators $(\\bar{d} p)(\\bar p^{\\hspace{0.25mm}\\prime} b)$ with $p,p^\\prime= u,c$ as well as $(\\bar{d}b) (\\bar\\tau\\tau)$. In both cases we find that for certain flavour or Lorentz structures of the operators sizable deviations of $\\Delta \\Gamma_d$ away from the Standard Model expectation cannot be excluded in a model-independent fashion.

  19. Niger Delta Crisis and Security Implications for the Nation State ...

    African Journals Online (AJOL)

    This paper seeks to examine the Niger Delta crisis and security implications for the Nigeria state. Its focus on the Niger Delta is because of the festering crisis in the region which is of critical importance to Nigeria. The Niger Delta is the nation's treasure base, the Niger Delta provides over 80 percent of government revenue, ...

  20. delta(13)C and delta(2)H isotope ratios in amphetamine synthesized from benzaldehyde and nitroethane.

    Science.gov (United States)

    Collins, Michael; Salouros, Helen; Cawley, Adam T; Robertson, James; Heagney, Aaron C; Arenas-Queralt, Andrea

    2010-06-15

    Previous work in these laboratories and by Butzenlechner et al. and Culp et al. has demonstrated that the delta(2)H isotope value of industrial benzaldehyde produced by the catalytic oxidation of toluene is profoundly positive, usually in the range +300 per thousand to +500 per thousand. Synthetic routes leading to amphetamine, methylamphetamine or their precursors and commencing with such benzaldehyde may be expected to exhibit unusually positive delta(2)H values. Results are presented for delta(13)C and delta(2)H isotope values of 1-phenyl-2-nitropropene synthesized from an industrial source of benzaldehyde, having a positive delta(2)H isotope value, by a Knoevenagel condensation with nitroethane. Results are also presented for delta(13)C and delta(2)H isotope values for amphetamine prepared from the resulting 1-phenyl-2-nitropropene. The values obtained were compared with delta(13)C and delta(2)H isotope values obtained for an amphetamine sample prepared using a synthetic route that did not involve benzaldehyde. Finally, results are presented for samples of benzaldehyde, 1-phenyl-2-nitropropene and amphetamine that had been seized at a clandestine amphetamine laboratory. Copyright (c) 2010 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.

  1. Stellar delta matter with delta-meson coupling constants constrained by QCD sum rule

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Antonio Ferreira da [Secretaria de Educacao, Cultura e Desportos do Estado de Roraima (SECD/RR), Boa Vista, RR (Brazil); Oliveira, Jose Carlos Teixeira de [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil); Rodrigues, Hilario [Centro Federal de Educacao Tecnologica (CEFET-RJ), Rio de Janeiro, RJ (Brazil); Duarte, Sergio Barbosa [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Chiapparini, Marcelo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2010-07-01

    The considerable presence of delta-resonances (30% of baryonic population) in the dense phase of relativistic heavy ion collisions leads to a great interest in the study of the delta matter formation in the deep interior of compact stars. In the present work we determine the equation of state and the population of baryons and leptons and discuss the effects of the baryon-meson coupling constants to the formation of delta matter in the stellar medium. We use the non-linear Walecka model consisting of the octet of baryons of spin 1=2 (n, p, {Lambda}{sup 0}, {Sigma}{sup -}, {Sigma}{sup 0}, {Sigma}{sup +}, {Xi}{sup -}, {Xi}{sup 0}) and baryonic resonances of spin 3=2, represented by the delta resonances ({Delta}{sup -}, ({Delta}{sup 0}, ({Delta}{sup +}, ({Delta}{sup ++}) and {Omega}{sup -}, in the baryonic sector. In the leptonic sector we consider the electrons and muons. The coupling constants between the hyperons {Lambda}, {Sigma}, and {Xi} and the mesons {omega} and {rho} are fixed by using SU(6) symmetry, while the hyperons-{sigma} coupling constants are constrained by the consistence of the hypernuclear potential in the nuclear matter with hypernuclear data. In addition, we use the finite density QCD sum rule to determine the possible values of delta-meson coupling constants. (author)

  2. The. delta. expansion and local gauge invariance

    Energy Technology Data Exchange (ETDEWEB)

    Bender, C.M. (Department of Physics, Washington University, St. Louis, Missouri 63130 (US)); Cooper, F. (Department of Physics, Brown University, Providence, Rhode Island 02912 Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexic o 87545); Milton, K.A. (Department of Physics, The Ohio State University, Columbus, Ohio 43210 Department of Physics and Astronomy, University of Oklahoma, Norman, Oklaho ma 73019)

    1989-08-15

    A recently proposed approximation method, called the {delta} expansion, was introduced in the context of a self-interacting scalar field theory. This approximation method offers the hope of obtaining nonperturbative information about a quantum field theory using perturbative techniques. In this paper we extend formally the {delta}-expansion methods to field theories having local gauge symmetry. We then compute the anomaly in the Schwinger model.

  3. The Okavango delta: The value of tourism

    OpenAIRE

    G Mopelwa; J Blignaut

    2014-01-01

    In Botswana, tourism is the second most important economic activity after diamond mining and trading. The Okavango Delta in northern Botswana is the largest single tourist centre in the country. This study estimates the total economic value of tourism in the Okavango Delta and compares this value to that of other sectors in the economy of Botswana. The results are compared to results of similar studies for tourist destinations elsewhere in the world, and the policy implications of the finding...

  4. Delta's inexpensive, reliable, and versatile third generation upper stage

    Science.gov (United States)

    Bonnett, E. W.; Schindler, W. R.

    1973-01-01

    The need for larger diameter fairings to encapsulate spacecraft designed to use Delta's increased lifting capabilities resulted in hammer-head design configurations that would have unaccepably degraded vehicle flight characteristics. This situation led to the development of the Straight Eight configuration. The towed mode arrangement for the second stage negated the requirement for the engine compartment structure, thus establishing the potential for an improved packaging of the hydraulic and pneumatic systems. Therefore, with cost reduction and reliability improvement objectives, a second stage propulsion system improvement program was initiated. The paper will describe these improvements and their system benefits.

  5. Hole states in diamond p-delta-doped field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Orozco, J C; Rodriguez-Vargas, I [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad Esquina con Paseo la Bufa S/N, CP 98060 Zacatecas, ZAC. (Mexico); Mora-Ramos, M E, E-mail: jcmover@correo.unam.m [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, CP 62209 Cuernavaca, MOR. (Mexico)

    2009-05-01

    The p-delta-doping in diamond allows to create high density two-dimensional hole gases. This technique has already been applied in the design and fabrication of diamond-based field effect transistors. Consequently, the knowledge of the electronic structure is of significant importance to understand the transport properties of diamond p-delta-doped systems. In this work the hole subbands of diamond p-type delta-doped quantum wells are studied within the framework of a local-density Thomas-Fermi-based approach for the band bending profile. The calculation incorporates an independent three-hole-band scheme and considers the effects of the contact potential, the delta-channel to contact distance, and the ionized impurity density.

  6. Topography of inland deltas: Observations, modeling, and experiments

    OpenAIRE

    Seybold, H. J.; Molnar, P.; Akça, Mehmet Devrim; Doumi, M.; Tavares, M. Cavalcanti; Shinbrot, T.; Andrade, J. S.; Kinzelbach, W.; Herrmann, H. J.

    2010-01-01

    The topography of inland deltas is influenced by the water-sediment balance in distributary channels and local evaporation and seepage rates. In this letter a reduced complexity model is applied to simulate inland delta formation, and results are compared with the Okavango Delta, Botswana and with a laboratory experiment. We show that water loss in inland deltas produces fundamentally different dynamics of water and sediment transport than coastal deltas, especially deposition associated with...

  7. Delta-Notch signaling and lateral inhibition in zebrafish spinal cord development

    Directory of Open Access Journals (Sweden)

    Givan Lee Anne

    2001-07-01

    Full Text Available Abstract Background Vertebrate neural development requires precise coordination of cell proliferation and cell specification to guide orderly transition of mitotically active precursor cells into different types of post-mitotic neurons and glia. Lateral inhibition, mediated by the Delta-Notch signaling pathway, may provide a mechanism to regulate proliferation and specification in the vertebrate nervous system. We examined delta and notch gene expression in zebrafish embryos and tested the role of lateral inhibition in spinal cord patterning by ablating cells and genetically disrupting Delta-Notch signaling. Results Zebrafish embryos express multiple delta and notch genes throughout the developing nervous system. All or most proliferative precursors appeared to express notch genes whereas subsets of precursors and post-mitotic neurons expressed delta genes. When we ablated identified primary motor neurons soon after they were born, they were replaced, indicating that specified neurons laterally inhibit neighboring precursors. Mutation of a delta gene caused precursor cells of the trunk neural tube to cease dividing prematurely and develop as neurons. Additionally, mutant embryos had excess early specified neurons, with fates appropriate for their normal positions within the neural tube, and a concomitant deficit of late specified cells. Conclusions Our results are consistent with the idea that zebrafish Delta proteins, expressed by newly specified neurons, promote Notch activity in neighboring precursors. This signaling is required to maintain a proliferative precursor population and generate late-born neurons and glia. Thus, Delta-Notch signaling may diversify vertebrate neural cell fates by coordinating cell cycle control and cell specification.

  8. The Okavango: Whose Delta is it?

    Science.gov (United States)

    Magole, Lapologang; Magole, Lefatshe Innocent

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

  9. Experimental and theoretical study of the longitudinal aerodynamic characteristics of delta and double-delta wings at Mach numbers of 1.60, 1.90, and 2.16

    Science.gov (United States)

    Wood, R. M.; Covell, P. F.

    1985-01-01

    An experimental and theoretical study was conducted to investigate the supersonic aerodynamic characteristics of delta and double-delta wings. Testing was conducted in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.60, 1.90, and 2.16. The double-delta wings exhibited lower zero-lift drag values than the delta wings having the same aspect ratio, whereas delta wings provided the lower drag due to lift. Deflections of the trailing-edge flaps for pitch control revealed that the induced aerodynamic forces were only a function of the flap planform and were independent of wing planform. The supporting theoretical analysis showed that the supersonic design and analysis system (SDAS) did not consistently predict all the longitudinal aerodynamic characteristics of the low-sweep, low-fineness-ratio wing-body configurations under investigation.

  10. Houtman Abrolhos Isotope (delta 18O, delta 13C) Data for 1795 to 1994

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — DESCRIPTION: VARIABLES AND UNITS: Column #1: core depth in mm Column #2: delta C-13 vs V-PDB Column #3: delta O-18 vs V-PDB Column #4: assigned date in years A.D....

  11. Impact of sea-level rise in a Mediteranean delta : The Ebro delta cast

    NARCIS (Netherlands)

    Sánchez-Arcilla, A.; Stive, M.D.F.; Jiménez, J.A.; García, M.A.

    1993-01-01

    In anticipation of a comprehensive, multidisciplinary study on the impact of climatic change on the Ebro Delta preliminary results are here presented of the response of the outer delta coast to present and future relative sea-level rise. Due to the absence of observations and predictions of regional

  12. The crystal structure of delta(3)-delta(2)-enoyl-CoA isomerase.

    Science.gov (United States)

    Mursula, A M; van Aalten, D M; Hiltunen, J K; Wierenga, R K

    2001-06-15

    The active-site geometry of the first crystal structure of a Delta(3)-Delta(2)-enoyl-coenzyme A (CoA) isomerase (the peroxisomal enzyme from the yeast Saccharomyces cerevisiae) shows that only one catalytic base, Glu158, is involved in shuttling the proton from the C2 carbon atom of the substrate, Delta(3)-enoyl-CoA, to the C4 atom of the product, Delta(2)-enoyl-CoA. Site-directed mutagenesis has been performed to confirm that this glutamate residue is essential for catalysis. This Delta(3)-Delta(2)-enoyl-CoA isomerase is a hexameric enzyme, consisting of six identical subunits. It belongs to the hydratase/isomerase superfamily of enzymes which catalyze a wide range of CoA-dependent reactions. The members of the hydratase/ isomerase superfamily have only a low level of sequence identity. Comparison of the crystal structure of the Delta(3)-Delta(2)-enoyl-CoA isomerase with the other structures of this superfamily shows only one region of large structural variability, which is in the second turn of the spiral fold and which is involved in defining the shape of the binding pocket. Copyright 2001 Academic Press.

  13. Interdisciplinary and Distance Education in the Delta: The Delta Health Education Partnership.

    Science.gov (United States)

    Skorga, Phyllis

    2002-01-01

    Describes the Delta Health Education Partnership, an interdisciplinary distance education program intended to recruit, educate, and retain interdisciplinary groups of primary care health practitioners to increase access to health care in medically underserved and health professional shortage areas of the lower Mississippi Delta. It spans six…

  14. Does {delta}m = {delta}E{sub rest}/c{sup 2}?

    Energy Technology Data Exchange (ETDEWEB)

    Redzic, Dragan V [Faculty of Physics, University of Belgrade, PO Box 368, 11001 Belgrade (Yugoslavia)

    2006-01-01

    We point out a logical possibility, based on special relativity, that the validity of Einstein's 1905 generalization, {delta}m = {delta}E{sub rest}/c{sup 2}, might depend on how the energy of a body is defined in special relativity. The analysis is another illustration of the importance of Ockham's razor in special relativity.

  15. A reduced-complexity model for river delta formation - Part 1: Modeling deltas with channel dynamics

    Science.gov (United States)

    Liang, M.; Voller, V. R.; Paola, C.

    2015-01-01

    In this work we develop a reduced-complexity model (RCM) for river delta formation (referred to as DeltaRCM in the following). It is a rule-based cellular morphodynamic model, in contrast to reductionist models based on detailed computational fluid dynamics. The basic framework of this model (DeltaRCM) consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include a depth-averaged flow field, water surface elevation and bed topography that evolve in time. Results show that DeltaRCM is able (1) to resolve a wide range of channel dynamics - including elongation, bifurcation, avulsion and migration - and (2) to produce a variety of deltas such as alluvial fan deltas and deltas with multiple orders of bifurcations. We also demonstrate a simple stratigraphy recording component which tracks the distribution of coarse and fine materials and the age of the deposits. Essential processes that must be included in reduced-complexity delta models include a depth-averaged flow field that guides sediment transport a nontrivial water surface profile that accounts for backwater effects at least in the main channels, both bedload and suspended sediment transport, and topographic steering of sediment transport.

  16. PENGINDERAAN JAUH DAN SISTEM INFORMASI GEOGRAFIS UNTUK MONITORING PERKEMBANGAN MORFOLOGI DELTA SUNGAI JENEBERANG MENGGUNAKAN CITRA LANDSAT MULTI TEMPORAL

    Directory of Open Access Journals (Sweden)

    Nursyamsi Junus

    2016-10-01

    musim juga sangat dominan dalam pembentukan delta Sungai Jeneberang dimana pada musim barat debit sungai yang tinggi membawa sejumah sedimen dan diendapkan pada bagian muara. Luas areal permukiman di kawasan delta dari tahun 1989-2006 bertambah sebesar 1392 ha.    ABSTRACT Objective of this research was exploit the image of Landsat TM and ETM+ to monitor geomorphology of Jeneberang river delta, change of coastline during 1989-2006 and also to study the ability of satellite image especially Landsat image for detecting geomorphology changes on Jeneberang River delta. Research area covers the area of Jeneberang River delta, Makassar Regency, South Sulawesi Province. Primary data obtained by using time series satellite images afterwards it processed with the Geographical Information System (GIS;. field surveys to measure wave, tide, current, suspended sediment.  Secondary data collected from Chamber of Meteorology and Geophysics and also another source such as topographic maps, pictures, statistic data, from research reports. Data analysis conducted with the integration of quantitative analysis and descriptive analysis where data from field measurement used to support the descriptive analysis by interpretation satellite image. Processing data using GIS obtain geomorphology change map at the Jeneberang River delta during 1989-2006. The result of research is obtained fluctuation of coastline and area of delta. Landform of delta continent have changed from multi lobate shape become lobate shape. Area of delta increasing about 8.84 ha/year but in 2001 to 2005, area of delta experiencing of reduction about 2,38 ha/year. Length of coastline increasingabout 23.10 km/year, but in 1999 to 2001 coastline decrease about 37.02 km/year because abrasion. Fluvial and marine influence play important role on the landform of Jeneberang River delta. Abrasion and sedimentation process happened at some part of delta. Season change also very dominant in forming of Jeneberang River delta

  17. On the calibration of continuous, high-precision delta18O and delta2H measurements using an off-axis integrated cavity output spectrometer.

    Science.gov (United States)

    Wang, Lixin; Caylor, Kelly K; Dragoni, Danilo

    2009-02-01

    The (18)O and (2)H of water vapor serve as powerful tracers of hydrological processes. The typical method for determining water vapor delta(18)O and delta(2)H involves cryogenic trapping and isotope ratio mass spectrometry. Even with recent technical advances, these methods cannot resolve vapor composition at high temporal resolutions. In recent years, a few groups have developed continuous laser absorption spectroscopy (LAS) approaches for measuring delta(18)O and delta(2)H which achieve accuracy levels similar to those of lab-based mass spectrometry methods. Unfortunately, most LAS systems need cryogenic cooling and constant calibration to a reference gas, and have substantial power requirements, making them unsuitable for long-term field deployment at remote field sites. A new method called Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) has been developed which requires extremely low-energy consumption and neither reference gas nor cryogenic cooling. In this report, we develop a relatively simple pumping system coupled to a dew point generator to calibrate an ICOS-based instrument (Los Gatos Research Water Vapor Isotope Analyzer (WVIA) DLT-100) under various pressures using liquid water with known isotopic signatures. Results show that the WVIA can be successfully calibrated using this customized system for different pressure settings, which ensure that this instrument can be combined with other gas-sampling systems. The precisions of this instrument and the associated calibration method can reach approximately 0.08 per thousand for delta(18)O and approximately 0.4 per thousand for delta(2)H. Compared with conventional mass spectrometry and other LAS-based methods, the OA-ICOS technique provides a promising alternative tool for continuous water vapor isotopic measurements in field deployments. Copyright 2009 John Wiley & Sons, Ltd.

  18. Comparison of CIELAB DeltaE(*) and CIEDE2000 color-differences after polymerization and thermocycling of resin composites.

    Science.gov (United States)

    Lee, Yong-Keun

    2005-07-01

    Though instrumental technologies have been widely used for quantifying color of esthetic dental materials, the sizes for the perceptible or acceptable color-difference varied. Instead of the CIELAB DeltaE(*)(DeltaE(ab)(*)) formula, the CIEDE2000 (DeltaE(00)) formula that included weighting and parametric functions was introduced. The objective of this study was to determine the correlation between color-difference values of DeltaE(ab)(*) and DeltaE(00) after polymerization and thermocycling of dental resin composites. Color-differences were calculated between unpolymerized and polymerized, and between polymerized and thermocycled resin composites. Color was measured relative to the standard illuminant D65 over a white background with SCE geometry. Regression analyses were performed between the color difference values of DeltaE(ab)(*) and DeltaE(00). There were significant correlations between DeltaE(ab)(*) values and DeltaE(00) values after polymerization and thermocycling (plightness, chroma and hue, the DeltaE(00) formula could be considered for the color evaluation of esthetic dental materials after confirming with human observer responses.

  19. Interactions among mu- and delta-opioid receptors, especially putative delta1- and delta2-opioid receptors, promote dopamine release in the nucleus accumbens.

    NARCIS (Netherlands)

    Hirose, N.; Murakawa, K.; Takada, K.; Oi, Y.; Suzuki, T.; Nagase, H.; Cools, A.R.; Koshikawa, N.

    2005-01-01

    The effect of interactions among mu- and delta-opioid receptors, especially the putative delta(1)- and delta(2)-opioid receptors, in the nucleus accumbens on accumbal dopamine release was investigated in awake rats by in vivo brain microdialysis. In agreement with previous studies, perfusion of the

  20. Delta FosB overexpression in the nucleus accumbens enhances sexual reward in female Syrian hamsters.

    Science.gov (United States)

    Hedges, V L; Chakravarty, S; Nestler, E J; Meisel, R L

    2009-06-01

    Repeated activation of the mesolimbic dopamine system results in persistent behavioral alterations accompanied by a pattern of neural plasticity in the nucleus accumbens (NAc). As the accumulation of the transcription factor Delta FosB may be an important component of this plasticity, the question addressed in our research is whether Delta FosB is regulated by sexual experience in females. We have shown that female Syrian hamsters, given sexual experience, exhibit several behavioral alterations including increased sexual efficiency with naïve male hamsters, sexual reward and enhanced responsiveness to psychomotor stimulants (e.g. amphetamine). We recently demonstrated that sexual experience increased the levels of Delta FosB in the NAc of female Syrian hamsters. The focus of this study was to explore the functional consequences of this induction by determining if the constitutive overexpression of Delta FosB by adeno-associated virus (AAV) vectors in the NAc could mimic the behavioral effects of sexual experience. Animals with AAV-mediated overexpression of Delta FosB in the NAc showed evidence of sexual reward in a conditioned place preference paradigm under conditions in which control animals receiving an injection of AAV-green fluorescent protein (GFP) into the NAc did not. Sexual behavior tests further showed that males paired with the AAV-Delta FosB females had increased copulatory efficiency as measured by the proportion of mounts that included intromission compared to males mated with the AAV-GFP females. These results support a role for Delta FosB in mediating natural motivated behaviors, in this case female sexual behavior, and provide new insight into the possible endogenous actions of Delta FosB.

  1. Evaluation of the La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} system as SOFC cathode material with 8YSZ and LSGM as electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid (CSIC),C/Sor Juana Ines de la Cruz 3, Campus Cantoblanco, 28049 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica,(CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2008-05-31

    Materials formulated as La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} (0 {<=} x {<=} 1) have been synthesised to be evaluated as possible cathode materials in SOFCs. Their crystal structures have been investigated by high-resolution neutron powder diffraction at RT so as to map out the phase diagram. The thermal expansion coefficients have been determined to be in the range of 10.8-13.0 x 10{sup -} {sup 6} K{sup -} {sup 1}. Total conductivity values are as good as 87 S cm{sup -} {sup 1} at 580 C for x = 0.4. In order to assess the performance of each oxide as cathode material, ac impedance measurements were carried out on La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}}/electrolyte/La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} symmetrical cells with either LSGM or 8YSZ as electrolyte material. For all the electrode compositions studied, the best specific resistance (ASR) values were obtained with LSGM as electrolyte. The better performance of x = 0.4 and 0.6 (ASR {proportional_to} 1 and ohm; cm{sup 2} at 850 C) compositions has been associated with the magnitude of the total conductivity and the matching of the TEC values of the cathodes with those of the electrolytes. (author)

  2. Sandy River Delta Habitat Restoration Project, Annual Report 2001.

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Virginia; Dobson, Robin L.

    2002-11-01

    The Sandy River Delta is located at the confluence of the Sandy and Columbia Rivers, just east of Troutdale, Oregon. It comprises about 1,400 land acres north of Interstate 84, managed by the USDA Forest Service, and associated river banks managed by the Oregon Division of State Lands. Three islands, Gary, Flag and Catham, managed by Metro Greenspaces and the State of Oregon lie to the east, the Columbia River lies to the north and east, and the urbanized Portland metropolitan area lies to the west across the Sandy River. Sandy River Delta was historically a wooded, riparian wetland with components of ponds, sloughs, bottomland woodland, oak woodland, prairie, and low and high elevation floodplain. It has been greatly altered by past agricultural practices and the Columbia River hydropower system. Restoration of historic landscape components is a primary goal for this land. The Forest Service is currently focusing on restoration of riparian forest and wetlands. Restoration of open upland areas (meadow/prairie) would follow substantial completion of the riparian and wetland restoration. The Sandy River Delta is a former pasture infested with reed canary grass, blackberry and thistle. The limited over story is native riparian species such as cottonwood and ash. The shrub and herbaceous layers are almost entirely non-native, invasive species. Native species have a difficult time naturally regenerating in the thick, competing reed canary grass, Himalayan blackberry and thistle. A system of drainage ditches installed by past owners drains water from historic wetlands. The original channel of the Sandy River was diked in the 1930's, and the river diverted into the ''Little Sandy River''. The original Sandy River channel has subsequently filled in and largely become a slough. The FS acquired approximately 1,400 acres Sandy River Delta (SRD) in 1991 from Reynolds Aluminum (via the Trust for Public Lands). The Delta had been grazed for many years

  3. Degradation Of Mangroves Ecosystem Of Indus Delta

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Peracha

    2015-08-01

    Full Text Available Indus Delta being the 6th largest delta of the world was earlier environmentally healthy and contributing its due share in the economic growth of the country. During the last six decades construction of reservoirs canals diversion of water for irrigation and considerable reduction in seasonal rains etc. substantially decreased the Indus water in the delta. The reduction of fresh water in the deltaic region threatened the livelihood of millions of fisher folk farmers marine inhabitants and as well as naturally rich mangroves ecosystem of the area. If the situation continues the country might lose its major share in revenue generation. Keeping in view the gravity of the circumstances preemptive measures are required to be taken forthwith. All stake-holders are to be apprised about the significance of the region and ask to play their respective role to save the delta. In this paper efforts have been made to develop a Mathematical Model that acquaints the government about the alarming situation particularly the degradation of the existence of Mangrove ecosystem in the Indus Delta.

  4. Open source integrated modeling environment Delta Shell

    Science.gov (United States)

    Donchyts, G.; Baart, F.; Jagers, B.; van Putten, H.

    2012-04-01

    In the last decade, integrated modelling has become a very popular topic in environmental modelling since it helps solving problems, which is difficult to model using a single model. However, managing complexity of integrated models and minimizing time required for their setup remains a challenging task. The integrated modelling environment Delta Shell simplifies this task. The software components of Delta Shell are easy to reuse separately from each other as well as a part of integrated environment that can run in a command-line or a graphical user interface mode. The most components of the Delta Shell are developed using C# programming language and include libraries used to define, save and visualize various scientific data structures as well as coupled model configurations. Here we present two examples showing how Delta Shell simplifies process of setting up integrated models from the end user and developer perspectives. The first example shows coupling of a rainfall-runoff, a river flow and a run-time control models. The second example shows how coastal morphological database integrates with the coastal morphological model (XBeach) and a custom nourishment designer. Delta Shell is also available as open-source software released under LGPL license and accessible via http://oss.deltares.nl.

  5. Inhibition of NMDARs in the nucleus reticularis of the thalamus produces delta frequency bursting

    Directory of Open Access Journals (Sweden)

    Yuchun Zhang

    2009-11-01

    Full Text Available Injection of NMDAR antagonist into the thalamus can produce delta frequency EEG oscillations in the thalamocortical system. It is surprising that an antagonist of an excitatory neurotransmitter should trigger such activity, and the mechanism is unknown. One hypothesis is that the antagonist blocks excitation of GABAergic cells, thus producing disinhibition. To test this hypothesis, we investigated the effect of NMDAR antagonist (APV on cells of the nucleus reticularis (nRT in rat brain slices, a thalamic nucleus that can serve as a pacemaker for thalamocortical delta oscillations and that is composed entirely of GABAergic neurons. We found, unexpectedly, that nRT cells are hyperpolarized by APV. This occurs because these cells have an unusual form of NMDAR (probably NR2C that contributes inward current at resting potential in response to ambient glutamate. The hyperpolarization produced by APV is sufficient to deinactivate T-type calcium channels, and these trigger rhythmic bursting at delta frequency. The APV-induced delta frequency bursting is abolished by dopamine D2 receptor antagonist, indicating that dopamine and NMDAR antagonist work synergistically to stimulate delta frequency bursting. Our results have significant implications concerning the electrophysiological basis of schizophrenia and bring together the NMDAR hypofunction, dopamine, and GABA theories of the disease. Our results suggest that NMDAR hypofunction and dopamine work synergistically on the GABAergic cells of the nRT to generate the delta frequency EEG oscillations, a thalamocortical dysrhythmia (TCD in the awake state that is an established abnormality in schizophrenia.

  6. (-)-Delta9-tetrahydrocannabinol antagonizes the peripheral cannabinoid receptor-mediated inhibition of adenylyl cyclase.

    Science.gov (United States)

    Bayewitch, M; Rhee, M H; Avidor-Reiss, T; Breuer, A; Mechoulam, R; Vogel, Z

    1996-04-26

    (-)-Delta9-Tetrahydrocannabinol ((-)-Delta9-THC) is the major active psychotropic component of the marijuana plant, Cannabis sativa. The membrane proteins that have been found to bind this material or its derivatives have been called the cannabinoid receptors. Two GTP-binding protein-coupled cannabinoid receptors have been cloned. CB1 or the neuronal cannabinoid receptor is found mostly in neuronal cells and tissues while CB2 or the peripheral cannabinoid receptor has been detected in spleen and in several cells of the immune system. It has previously been shown that activation of CB1 or CB2 receptors by cannabinoid agonists inhibits adenylyl cyclase activity. Utilizing Chinese hamster ovary cells and COS cells transfected with the cannabinoid receptors we report that (-)-Delta9-THC binds to both receptors with similar affinity. However, in contrast to its capacity to serve as an agonist for the CB1 receptor, (-)-Delta9-THC was only able to induce a very slight inhibition of adenylyl cyclase at the CB2 receptor. Morever, (-)-Delta9-THC antagonizes the agonist-induced inhibition of adenylyl cyclase mediated by CB2. Therefore, we conclude that (-)-Delta9-THC constitutes a weak antagonist for the CB2 receptor.

  7. Using helicopter TEM to delineate fresh water and salt water zones in the aquifer beneath the Okavango Delta, Botswana

    Science.gov (United States)

    Podgorski, Joel E.; Kinzelbach, Wolfgang K. H.; Kgotlhang, Lesego

    2017-09-01

    The Okavango Delta is a vast wetland wilderness in the middle of the Kalahari Desert of Botswana. It is a largely closed hydrological system with most water leaving the delta by evapotranspiration. In spite of this, the channels and swamps of the delta remain surprisingly low in salinity. To help understand the hydrological processes at work, we reanalyzed a previous inversion of data collected from a helicopter transient electromagnetic (HTEM) survey of the entire delta and performed an inversion of a high resolution dataset recorded during the same survey. Our results show widespread infiltration of fresh water to as much as ∼200 m depth into the regional saline aquifer. Beneath the western delta, freshwater infiltration extends to only about 80 m depth. Hydrological modeling with SEAWAT confirms that this may be due to rebound of the regional saltwater-freshwater interface following the cessation of surface flooding over this part of the delta in the 1880s. Our resistivity models also provide evidence for active and inactive saltwater fingers to as much as ∼100 m beneath islands. These results demonstrate the great extent of freshwater infiltration across the delta and also show that all vegetated areas along the delta's channels and swamps are potential locations for transferring solutes from surface water to an aquifer at depth.

  8. Challenges Facing the Sacramento–San Joaquin Delta: Complex, Chaotic, or Simply Cantankerous?

    Directory of Open Access Journals (Sweden)

    Samuel N. Luoma

    2015-09-01

    Full Text Available doi: http://dx.doi.org/10.15447/sfews.2015v13iss3art7Freshwater is a scarce and precious resource in California; its overall value is being made clear by the current severe drought. The Sacramento–San Joaquin Delta is a critical node in a complex water supply system that extends throughout much of the western U.S. wherein demand is exceeding supply. The Delta also underpins a major component of the U.S. economy, helps feed a substantial part of the country, is a unique and valuable ecological resource, and is a place with a rich cultural heritage. Sustaining the Delta is a problem that manifests itself in many dimensions including the physical structure of the Delta, the conflicting demands for water, changing water quality, rapidly evolving ecological character, and high institutional complexity. The problems of the California Delta are increasingly complex, sometimes chaotic, and always contentious. There is general agreement that current management will sustain neither the Delta ecosystem nor high-quality water exports, as required under the Delta Reform Act, so there is a renewed urgency to address all dimensions of the problem aggressively. Sustainable management of the Delta ecosystem and California’s highly variable water supply, in the face of global climate change, will require bold political decisions that include adjustments to the infrastructure but give equal emphasis to chronic overuse and misuse of water, promote enhanced efficiency of water use, and facilitate new initiatives for ecosystem recovery. This new approach will need to be underpinned by collaborative science that supports ongoing evaluation and re-adjustment of actions. Problems like the Delta are formally “wicked" problems that cannot be “solved” in the traditional sense, but they can be managed with appropriate knowledge and flexible institutions. Where possible, it is advisable to approach major actions incrementally, with an eye toward avoiding

  9. CASSCF/CI calculations for first row transition metal hydrides - The TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), FeH(4,6-delta) and NiH(2-delta) states

    Science.gov (United States)

    Walch, S. P.; Bauschlicher, C. W., Jr.

    1983-01-01

    Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.

  10. Spin amplitudes for NN. -->. N. delta

    Energy Technology Data Exchange (ETDEWEB)

    Silbar, R.R. (Paris-11 Univ., 91 - Orsay (France). Div. de Physique Theorique; Los Alamos National Lab., NM (USA). Theoretical Div.); Lombard, R.J. (Paris-11 Univ., 91 - Orsay (France). Div. de Physique Theorique); Kloet, W.M. (Rutgers - the State Univ., New Brunswick, NJ (USA). Dept. of Physics and Astronomy)

    1982-06-21

    The scattering amplitude for NN..-->..N..delta.. is decomposed into sixteen independent spin-space operators Osub(i), where the corresponding coefficients Asub(i) only depend on scattering angle, incoming energy, and the ..delta..-mass. In addition to the commonly used vector spin-transition matrix, it is necessary to also employ a tensor spin-transition matrix. The Osub(i) can be chosen in two ways, either to facilitate discussion of underlying dynamical mechanisms or to simplify the antisymmetrization with respect to the initial nucleons. Relations between the Asub(i) (THETA) and the (LSJ) partial-wave amplitudes are given. We evaluate the Asub(i) using partial-wave amplitudes calculated elsewhere in a unitary three-body model with one-pion-exchange driving terms. Many amplitudes are of competing importance after antisymmetrization, and they are strongly dependent upon incident energy and ..delta.. invariant mass.

  11. The Okavango delta: The value of tourism

    Directory of Open Access Journals (Sweden)

    G Mopelwa

    2014-07-01

    Full Text Available In Botswana, tourism is the second most important economic activity after diamond mining and trading. The Okavango Delta in northern Botswana is the largest single tourist centre in the country. This study estimates the total economic value of tourism in the Okavango Delta and compares this value to that of other sectors in the economy of Botswana. The results are compared to results of similar studies for tourist destinations elsewhere in the world, and the policy implications of the findings are highlighted. The study uses secondary data to estimate the direct consumptive and non-consumptive use value, and a survey among tourists to determine the existence value of the Okavango Delta.

  12. An Overview of Multi-Dimensional Models of the Sacramento–San Joaquin Delta

    Directory of Open Access Journals (Sweden)

    Michael L. MacWilliams

    2016-12-01

    Full Text Available doi: https://doi.org/10.15447/sfews.2016v14iss4art2Over the past 15 years, the development and application of multi-dimensional hydrodynamic models in San Francisco Bay and the Sacramento–San Joaquin Delta has transformed our ability to analyze and understand the underlying physics of the system. Initial applications of three-dimensional models focused primarily on salt intrusion, and provided a valuable resource for investigating how sea level rise and levee failures in the Delta could influence water quality in the Delta under future conditions. However, multi-dimensional models have also provided significant insights into some of the fundamental biological relationships that have shaped our thinking about the system by exploring the relationship among X2, flow, fish abundance, and the low salinity zone. Through the coupling of multi-dimensional models with wind wave and sediment transport models, it has been possible to move beyond salinity to understand how large-scale changes to the system are likely to affect sediment dynamics, and to assess the potential effects on species that rely on turbidity for habitat. Lastly, the coupling of multi-dimensional hydrodynamic models with particle tracking models has led to advances in our thinking about residence time, the retention of food organisms in the estuary, the effect of south Delta exports on larval entrainment, and the pathways and behaviors of salmonids that travel through the Delta. This paper provides an overview of these recent advances and how they have increased our understanding of the distribution and movement of fish and food organisms. The applications presented serve as a guide to the current state of the science of Delta modeling and provide examples of how we can use multi-dimensional models to predict how future Delta conditions will affect both fish and water supply.

  13. Liquefaction potential of Nile delta, Egypt

    Directory of Open Access Journals (Sweden)

    Elsayed Fergany

    2017-06-01

    Full Text Available Understanding how sedimentary basins respond to seismic-wave energy generated by earthquake events is a significant concern for seismic-hazard estimation and risk analysis. The main goal of this study is assessing the vulnerability index, Kg, as an indicator for liquefaction potential sites in the Nile delta basin based on the microtremor measurements. Horizontal to Vertical spectral ratio analyses (HVSR of ambient noise data, which was conducted in 2006 at 120 sites covering the Nile delta from south to north were reprocessed using Geopsy software. HVSR factors of amplification, A, and fundamental frequency, F, were calculated and Kg was estimated for each measurement. The Kg value varies widely from south toward north delta and the potential liquefaction places were estimated. The higher vulnerability indices are associated with sites located in southern part of the Nile delta and close to the branches of Nile River. The HVSR factors were correlated with geologic setting of the Nile delta and show good correlations with the sediment thickness and subsurface stratigraphic boundaries. However, we note that sites located in areas that have greatest percentage of sand also yielded relatively high Kg values with respect to sites in areas where clay is abundant. We concluded that any earthquake with ground acceleration more than 50 gal at hard rock can cause a perceived deformation of sandy sediments and liquefaction can take place in the weak zones of Kg ≥ 20. The worst potential liquefaction zones (Kg > 30 are frequently joined to the Damietta and Rosetta Nile River branches and south Delta where relatively coarser sand exists. The HVSR technique is a very sensitive tool for lithological stratigraphy variations in two dimensions and varying liquefaction susceptibility.

  14. Liquefaction potential of Nile delta, Egypt

    Science.gov (United States)

    Fergany, Elsayed; Omar, Khaled

    2017-06-01

    Understanding how sedimentary basins respond to seismic-wave energy generated by earthquake events is a significant concern for seismic-hazard estimation and risk analysis. The main goal of this study is assessing the vulnerability index, Kg, as an indicator for liquefaction potential sites in the Nile delta basin based on the microtremor measurements. Horizontal to Vertical spectral ratio analyses (HVSR) of ambient noise data, which was conducted in 2006 at 120 sites covering the Nile delta from south to north were reprocessed using Geopsy software. HVSR factors of amplification, A, and fundamental frequency, F, were calculated and Kg was estimated for each measurement. The Kg value varies widely from south toward north delta and the potential liquefaction places were estimated. The higher vulnerability indices are associated with sites located in southern part of the Nile delta and close to the branches of Nile River. The HVSR factors were correlated with geologic setting of the Nile delta and show good correlations with the sediment thickness and subsurface stratigraphic boundaries. However, we note that sites located in areas that have greatest percentage of sand also yielded relatively high Kg values with respect to sites in areas where clay is abundant. We concluded that any earthquake with ground acceleration more than 50 gal at hard rock can cause a perceived deformation of sandy sediments and liquefaction can take place in the weak zones of Kg ≥ 20. The worst potential liquefaction zones (Kg > 30) are frequently joined to the Damietta and Rosetta Nile River branches and south Delta where relatively coarser sand exists. The HVSR technique is a very sensitive tool for lithological stratigraphy variations in two dimensions and varying liquefaction susceptibility.

  15. Delta Scuti and related stars - Review

    Science.gov (United States)

    Breger, M.; Stockenhuber, H.

    Present knowledge on Delta Scuti stars, short-period pulsators of spectral types A and F situated on or above the main sequence, is reviewed. The topics discussed include: pulsation periods, pulsational mode-typing through line profiles, cluster stars, and SX Phe-type variables. The position of Delta Scuti stars in the H-R diagram is shown along with the observed period-luminosity-color relation for the stars. Correlations of average pulsation period and M(v) with cluster age are given, showing that the observed correlations can be explained by the PLC relation and main sequence evolution of the clusters.

  16. Hepatitis Delta Infections in Toronto, Ontario

    OpenAIRE

    S. Victor Feinman; Barnet Berris; John L. Gerin; Robert H. Purcell

    1988-01-01

    This study assessed the prevalence of hepatitis delta virus infection, the relation of this infection to the clinical and histological status and to the geographic origin of 216 patients with hepatitis B virus infection in Toronto, Ontario. Evidence of delta infection was present in 13 of the 216 patients (6.0%). It was more common in patients with acute hepatitis (11.1%) and with chronic hepatitis (16.7%) than in asymptomatic carriers (3.6%). It was not present in the three patients with hep...

  17. Abraham Reef Stable Isotope Data (delta 13C, delta 18O, delta 14C) for 1635-1957

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Site: Abraham Reef, 22ó 06'S, 153ó 00'E, Porites australiensus, Radiocarbon (delta 14C) and Stable Isotope (del 18O and del 13C) results from bi-annual samples from...

  18. Pb-isotopic evidence for U-Th-Pb behavior in a prograde amphibolite to granulite facies transition from the Lewisian complex of north-west Scotland: Implications for Pb-Pb dating

    Energy Technology Data Exchange (ETDEWEB)

    Whitehouse, M.J. (Univ. of Oxford (England))

    1989-03-01

    Two end-member types of U-Pb fractionation behavior are recognized: type I in which Pb-isotopic homogenization occurs, and type II, in which Pb-isotopic homogenization is incomplete or absent. Type II can be further subdivided into three categories depending upon the relationship of the post-fractionation {mu}{sub 3} ({sup 238}U/{sup 204}Pb) value to prefractionation {mu}{sub 2}. In type IIa, {mu}{sub 3} is unrelated to {mu}{sub 2}; in type IIb, {mu}{sub 3} = k {mu}{sub 2}, where k is a constant; in type IIc, {mu}{sub 3} values are uniform. Each of these types of behavior results in a predictable effect upon observed uranogenic Pb-isotope systematics which may lead to an incorrect geochronological interpretation. An example of the relationship between these specific types of U-Pb behavior and metamorphic grade is provided from the late-Archaean Lewisian complex of N.W. Scotland. This complex was metamorphosed during the {approximately}2,660 Ma Badcallian event. A consideration of the thorogenic Pb-isotopic data reveals a systematic variation during prograde metamorphism. An attempt to test the model of 2,660 Ma initial ratio inhomogeneity by analysis of K-feldspars from the amphibolite facies gneiss suite reveals {approximately}1,700 Ma Laxfordian resetting of their Pb-isotope systematics. This study has implications for Pb/Pb geochronological data particularly in lower grade metamorphic terrains. It suggests that reliable isochrons may only be generated by type I behavior, or by the imposition of high {mu}{sub 3} values during type IIa behavior at higher grades of metamorphism.

  19. The leading-edge vortex of swift-wing shaped delta wings

    Science.gov (United States)

    Muir, Rowan; Arredondo-Galeana, Abel; Viola, Ignazio Maria

    2017-11-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the Leading-Edge Vortex (LEV) for lift generation in a variety of flight conditions. In this investigation, a model non-slender delta shaped wing with a sharp leading-edge is tested at low Reynolds Number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the un-modified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift-wing shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds Number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta shaped wing. This work received funding from the Engineering and Physical Sciences Research Council [EP/M506515/1] and the Consejo Nacional de Ciencia y Tecnología (CONACYT).

  20. Strategies for Mitigation of Flood Risk in the Niger Delta, Nigeria ...

    African Journals Online (AJOL)

    The study observes that for flood risk mitigation strategies to be effective in the Niger Delta, there is need for establishment of coastal management zone authority, land-use zoning, legislation, building codes, flood forecasting and warning systems, flood insurance and engineering control of the major river systems ...

  1. Oil politics and violence in postcolonial Niger Delta drama | Otu ...

    African Journals Online (AJOL)

    Oil politics and violence in postcolonial Niger Delta drama. ... African state and an oppressive colonial or neo-colonial European power. ... and as such contemporary postcolonial Niger Delta drama can be described as drama of individualism ...

  2. Delta 9-tetrahydrocannabinol produced discrimination in pigeons.

    Science.gov (United States)

    Henriksson, B G; Johansson, J O; Järbe, T U

    1975-01-01

    In an operant situation pigeons learned to peck one response key 90 min after an injection of 0.25mg/kg delta9-tetrahydrocannabinol (delta9-THC) and another key when trained nondrugged. When tested with doses of delta9-THC lwer than the training dose the birds disciminated 0.20 mg/kg of the drug from the nondrugged state but not 0.15 mg/kg or lower doses. The animals were able to discriminate the drug state from the nondrugged 180 min but not 360 min after the injection At a shorter interval (45 min) both drug and nondrug responding appeared. Cannabinol and cannabidiol (4.0 - 8.0 mg/kg) did not elicit any drug responses, nor did pentobarbital, ditran or amphetamine. Tests with LSD resulted in both drug and nondrug responding. When administering noncannabinoid drugs in combination with delta9-THC 0.15 mg/kg the birds responded at the key associated with the drug state, suggesting interactional effects.

  3. Bioluminescent hydrocarbonclastic bacteria of the Niger Delta ...

    African Journals Online (AJOL)

    Utilization of three petroleum hydrocarbons (Mobil SAE 40 Engine Oil, Diesel and Bonny light Crude Oil) by four bioluminescent bacteria (Vibrio harveyi, V. fisheri, Photobacterium leiognathi and P. Phosphoreum isolated from the Bonny estuary in the Niger Delta, Nigeria was investigated. Microbial utilization was monitored ...

  4. Error Minimization of Polynomial Approximation of Delta

    Indian Academy of Sciences (India)

    The difference between Universal time (UT) and Dynamical time (TD), known as Delta ( ) is tabulated for the first day of each year in the Astronomical Almanac. During the last four centuries it is found that there are large differences between its values for two consecutive years. Polynomial approximations have been ...

  5. The Delta Team: Empowering Adolescent Girls.

    Science.gov (United States)

    Hood, Marian White

    1994-01-01

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

  6. Water quality in the Okavango Delta

    African Journals Online (AJOL)

    2010-03-12

    Mar 12, 2010 ... This review will discuss levels of water quality parameters, such as .... have a cascading negative impact on species at higher trophic levels, such as fish, ... into water through photosynthesis by plants and phytoplankton or via diffusion ...... Delta, Botswana, and its contribution to the structure and function.

  7. All about the Dirac Delta Function (?)

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 8. All about the Dirac Delta Function (?). V Balakrishnan. General Article Volume 8 Issue 8 August 2003 pp 48-58. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/008/08/0048-0058. Keywords.

  8. A delta configured auxiliary resonant snubber inverter

    Energy Technology Data Exchange (ETDEWEB)

    Lai, J.S.; Young, R.W.; Ott, G.W. Jr.; McKeever, J.W. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.; Peng, F.Z. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)

    1995-09-01

    A delta ({Delta}) configured auxiliary resonant snubber inverter is developed to overcome the voltage floating problem in a wye (Y) configured resonant snubber inverter. The proposed inverter is to connect auxiliary resonant branches between phase outputs to avoid a floating point voltage which may cause over-voltage failure of the auxiliary switches. Each auxiliary branch consists of a resonant inductor and a reverse blocking auxiliary switch. Instead of using an anti-paralleled diode to allow resonant current to flow in the reverse direction, as in the Y-configured version, the resonant branch in the {Delta}-configured version must block the negative voltage, typically done by a series diode. This paper shows single-phase and three-phase versions of {Delta}-configured resonant snubber inverters and describes in detail the operating principle of a single-phase version. The extended three-phase version is proposed with non-adjacent state space vector modulation. For hardware implementation, a single-phase 1-kW unit and a three-phase 100-kW unit were built to prove the concept. Experimental results show the superiority of the proposed topology.

  9. Delta governance: The DNA of a specific kind of urbanization

    OpenAIRE

    Boelens, L.

    2014-01-01

    Urbanization is the result of the way leading actors, volatile factors, and historic and dynamic institutional settings interact. However, major differences occur between what we might call Capital and Delta metropolitan areas. This paper compares the governance of two of these Metropolitan Delta Areas: the Euro Delta of the Rhine–Meuse–Scheldt and the Pearl River Delta of the Xi–Bei–Dong – partly historically but also with respect to recent developments within governments, businesses and civ...

  10. Regional controls on geomorphology, hydrology, and ecosystem integrity in the Orinoco Delta, Venezuela

    Science.gov (United States)

    Warne, A.G.; Meade, R.H.; White, W.A.; Guevara, E.H.; Gibeaut, J.; Smyth, R.C.; Aslan, A.; Tremblay, T.

    2002-01-01

    Interacting river discharge, tidal oscillation, and tropical rainfall across the 22,000 km2 Orinoco delta plain support diverse fresh and brackish water ecosystems. To develop environmental baseline information for this largely unpopulated region, we evaluate major coastal plain, shallow marine, and river systems of northeastern South America, which serves to identify principal sources and controls of water and sediment flow into, through, and out of the Orinoco Delta. The regional analysis includes a summary of the geology, hydrodynamics, sediment dynamics, and geomorphic characteristics of the Orinoco drainage basin, river, and delta system. Because the Amazon River is a major source of sediment deposited along the Orinoco coast, we summarize Amazon water and sediment input to the northeastern South American littoral zone. We investigate sediment dynamics and geomorphology of the Guiana coast, where marine processes and Holocene history are similar to the Orinoco coast. Major factors controlling Orinoco Delta water and sediment dynamics include the pronounced annual flood discharge; the uneven distribution of water and sediment discharge across the delta plain; discharge of large volumes of water with low sediment concentrations through the Rio Grande and Araguao distributaries; water and sediment dynamics associated with the Guayana littoral current along the northeastern South American coast; inflow of large volumes of Amazon sediment to the Orinoco coast; development of a fresh water plume seaward of Boca Grande; disruption of the Guayana Current by Trinidad, Boca de Serpientes, and Gulf of Paria; and the constriction at Boca de Serpientes. ?? 2002 Elsevier Science B.V. All rights reserved.

  11. Plasma Sheath Behavior of the ProSEDS Delta II

    Science.gov (United States)

    Wright, K. H.; Stone, N. H.; Gilchrist, B. E.; Vaughn, J.; Garbe, G.

    2003-01-01

    The Propulsive Small Expendable Deployer System (ProSEDS) mission is a demonstration of the orbit lowering capabilities of an electrodynamic tether. The system is sequenced through various electrical modes, involving both open circuit and closed circuit configurations, so that the performance capabilities of the system can be studied. Ionospheric electrons are collected on the upper end of the bare tether, conducted through the tether, and returned to the ionosphere at the lower end (Delta I1 2nd stage) via the operation of a Hollow Cathode Plasma Contactor (HCPC). The working gas of the HCPC is xenon. Environmental plasma measurements and sheath potential are obtained from the Differential Ion Flux Probe w/Mass Analysis (DIFPM) and Langmuir Probe and Spacecraft Potential (LPSP) instruments. Each instrument has three sensors symmetrically placed about the strut section of the Delta 2nd stage. A magnetometer is also included in the ProSEDS instrumentation suite. An initial analysis of the rocket stage sheath behavior as a function of ProSEDS configuration (open or closed circuit), ambient ionospheric density, orientation to velocity vector (ram-wake influence), and magnetic field orientation is presented. An initial assessment on how well the plasma contactor grounded the rocket stage is also presented.

  12. Delta Power Control Strategy for Multi-String Grid-Connected PV Inverters

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    With a still increasing penetration level of grid-connected PV systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required...... for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control for grid-connected PV systems is presented, where the residential/commercial multi-string PV inverter configuration is adopted. This control strategy is a combination of Maximum...... Power Point Tracking (MPPT) and Constant Power Generation (CPG) modes. In this control scheme, one PV string operating in the MPPT mode estimates the available power, while the other PV strings regulate the total PV power by the CPG control strategy in such a way that the delta power constraint...

  13. Delta Power Control Strategy for Multistring Grid-Connected PV Inverters

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2017-01-01

    With a still increasing penetration level of grid-connected photovoltaic (PV) systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation......, is required for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control (DPC) for grid-connected PV systems is presented, where the multistring PV inverter configuration is adopted. This control strategy is a combination of maximum power point...... tracking (MPPT) and constant power generation (CPG) modes. In this control scheme, one PV string operating in the MPPT mode estimates the available power, whereas the other PV strings regulate the total PV power by the CPG control strategy in such a way that the delta power constraint for the entire PV...

  14. Measurements of $\\Delta m_d$, $\\Delta m_s$, and $\\sin 2 \\beta$ with LHCb

    CERN Document Server

    Wishahi, Julian

    2012-01-01

    We present measurements of the oscillation frequencies $\\Delta m_d$ and $\\Delta m_s$ of $B$ meson mixing as well as a measurement of the time-dependent CP-asymmetry in decays of $B^0\\to J/\\psi K_{\\text{S}}^0$ based on $1.0\\,\\text{fb}^{-1}$ of data collected by the LHCb experiment in 2011. These measurements give valuable input to tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.

  15. Transformations of Urbanising Delta Landscape. An Historic Examination of Dealing with the Impacts of Climate Change for the Kaoping River Delta in Taiwan

    Directory of Open Access Journals (Sweden)

    Chen Kun Chung

    2014-10-01

    Full Text Available This dissertation argues that the floods following extreme precipitation result not
only from very heavy rainfall but also from the significant impact of human activities on natural water systems. While most literature emphasises that the increasing magnitude of storm rainfall extends beyond the original protection standards of hydrologic facilities in highly populated delta cities. Based on the knowledge of urban morphology, this study analyses how human systems have affected the transformation of natural water processes in the Kaoping River Delta. The relationship between human environments and natural landscape is illustrated via a 3-layer analytical framework which consists of a natural landscape layer, an infrastructure layer and an occupation layer. This layer-based approach views landscapes as a whole system in which each element interacts with the others. In order to transcend the limitations of traditional urban morphology and the overlay-mapping method, this research initiates an analysis framework with the delta scale from a deductive perspective. Furthermore,
it argues that the significant progress of infrastructure technology is the crucial factor to dominate the transformation of modern urban pattern. This influence could be identified by the analytic process of the 3-layer approach from the perspective of the delta or regional scale. This new starting point of a theoretical framework for analysing urban forms has been proved in the Kaoping Delta case. Furthermore, it could be a new and valid theoretical background to extend the knowledge of urban morphology.The formal transformation of the Kaoping Delta is divided into four main periods, which reveals human activities have affected the operation of natural systems since a century ago. From a delta scale perspective, those effects interacting between different layers can be identified in six different topographies (in italics of the whole river catchment area.A. The dike

  16. Transformations of Urbanising Delta Landscape. An Historic Examination of Dealing with the Impacts of Climate Change for the Kaoping River Delta in Taiwan

    Directory of Open Access Journals (Sweden)

    Chen Kun Chung

    2014-10-01

    Full Text Available This dissertation argues that the floods following extreme precipitation result not
only from very heavy rainfall but also from the significant impact of human activities on natural water systems. While most literature emphasises that the increasing magnitude of storm rainfall extends beyond the original protection standards of hydrologic facilities in highly populated delta cities. Based on the knowledge of urban morphology, this study analyses how human systems have affected the transformation of natural water processes in the Kaoping River Delta. The relationship between human environments and natural landscape is illustrated via a 3-layer analytical framework which consists of a natural landscape layer, an infrastructure layer and an occupation layer. This layer-based approach views landscapes as a whole system in which each element interacts with the others. In order to transcend the limitations of traditional urban morphology and the overlay-mapping method, this research initiates an analysis framework with the delta scale from a deductive perspective. Furthermore,
it argues that the significant progress of infrastructure technology is the crucial factor to dominate the transformation of modern urban pattern. This influence could be identified by the analytic process of the 3-layer approach from the perspective of the delta or regional scale. This new starting point of a theoretical framework for analysing urban forms has been proved in the Kaoping Delta case. Furthermore, it could be a new and valid theoretical background to extend the knowledge of urban morphology. The formal transformation of the Kaoping Delta is divided into four main periods, which reveals human activities have affected the operation of natural systems since a century ago. From a delta scale perspective, those effects interacting between different layers can be identified in six different topographies (in italics of the whole river catchment area. A. The dike

  17. Environmental challenges in Nigeria's Delta Region and Agriculture ...

    African Journals Online (AJOL)

    The paper discussed the environmental challenges in the Niger-Delta region of Nigeria with emphasis on the impacts on agricultural production. It thus discussed the concepts of Niger-Delta, Environmental pollution, Niger-Delta crises and Agriculture. The paper posits that there are positive relationships between these ...

  18. Surface water quality in the Okavango Delta panhandle, Botswana ...

    African Journals Online (AJOL)

    The Okavango Delta, a Ramsar and a World Heritage Site, is an important source of food and water in the Kalahari Desert of southern Africa. Although the eastern delta fan is a protected area, the rest, including the upstream panhandle, is unprotected. Water quality in the Okavango Delta panhandle from Popa Falls, ...

  19. Deltas, Vulnerability, and Climate Change: Migration as an Adaptation

    International Development Research Centre (IDRC) Digital Library (Canada)

    Deltas, Vulnerability, and Climate Change: Migration as an Adaptation. Deltas in Africa and South Asia have some of the highest population densities in the world. Many residents along the deltas live in poverty and depend on livelihoods that are sensitive to a changing climate. This research project will examine the issue.

  20. The Economic Dimensions of the Niger Delta Ethnic Conflicts (Pp ...

    African Journals Online (AJOL)

    User

    employment and strategic benefits preferentially to their ethnic brethren. Discrimination against the Niger Delta ethnic groups in the award of contract jobs and employment became the order to the day. The Niger Delta .... roads and bridges across the Niger Delta will not reduce the unemployment problem, which is the ...

  1. Human T cell receptor gamma delta + T cells

    NARCIS (Netherlands)

    Spits, H.

    1991-01-01

    TCR gamma delta + T cells represent a minority of CD3+ T cells in many species including man. The molecular structure of the TCR gamma and delta loci in man is well understood. The gamma and delta loci contain V, D, J and C gene segments. These segments do not rearrange randomly but in a

  2. Vulnerability and Resilience of the Niger Delta Coastal Communities to Pollution and Environmental Degradation

    Science.gov (United States)

    Ndimele, P. E.; Whenu, O. O.; Anwan, H. R.; Anetekhai, M. A.

    2016-02-01

    The Niger Delta is Africa's largest delta consisting of the third largest mangrove forest in the world and covering 70,000km2 of Nigeria land mass. This delta is the largest wetland in Africa and among the ten most important wetland and marine ecosystems in the world. The delta is home to all of Nigeria's endemic or near-endemic mammal species and to six IUCN Red List mammals. The Niger Delta harbours globally outstanding fish fauna and displays exceptional evolutionary phenomena with its higher taxonomic endemism and distinct species assemblages. The Niger delta is blessed with abundance of natural and human resources, including the majority of Nigeria's oil and gas deposits, good agricultural land, extensive forests, excellent fisheries as well as a well-developed industrial base, a large labour force and a vibrant private sector. However, this fragile but rich ecosystem is seriously threatened by increased industrial pollution, resource over-exploitation and environmental degradation caused by over six decades of oil exploitation. Aquatic life has been destroyed with the pollution of traditional fishing grounds, exacerbating hunger and poverty in fishing communities. The multifarious use of the delta has led to human-induced changes in biota, habitats and landscapes necessitating the development of a holistic policy that considers all the interacting factors in the ecosystem. Taking a systems approach incorporating an understanding of The Ecosystem Approach, vulnerability, resilience, the DPSIR framework, ecosystem services and societal benefits are integrated in order to evolve a management tool that will result in sustainable resource exploitation, improvement in living standards of locals and restoration of the ecosystem.

  3. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity

    Science.gov (United States)

    Darby, Stephen E.; Hackney, Christopher R.; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R.; Best, James L.; Nicholas, Andrew P.; Aalto, Rolf

    2016-11-01

    The world’s rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being ‘drowned’ by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world’s great deltas. We demonstrate that spatial variations in the Mekong’s suspended sediment load are correlated (r = 0.765, P < 0.1) with observed variations in tropical-cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world’s major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  4. Genetic ablation of delta opioid receptors in nociceptive sensory neurons increases chronic pain and abolishes opioid analgesia.

    Science.gov (United States)

    Gaveriaux-Ruff, Claire; Nozaki, Chihiro; Nadal, Xavier; Hever, Xavier C; Weibel, Raphael; Matifas, Audrey; Reiss, David; Filliol, Dominique; Nassar, Mohammed A; Wood, John N; Maldonado, Rafael; Kieffer, Brigitte L

    2011-06-01

    Opioid receptors are major actors in pain control and are broadly distributed throughout the nervous system. A major challenge in pain research is the identification of key opioid receptor populations within nociceptive pathways, which control physiological and pathological pain. In particular, the respective contribution of peripheral vs. central receptors remains unclear, and it has not been addressed by genetic approaches. To investigate the contribution of peripheral delta opioid receptors in pain control, we created conditional knockout mice where delta receptors are deleted specifically in peripheral Na(V)1.8-positive primary nociceptive neurons. Mutant mice showed normal pain responses to acute heat and to mechanical and formalin stimuli. In contrast, mutant animals showed a remarkable increase of mechanical allodynia under both inflammatory pain induced by complete Freund adjuvant and neuropathic pain induced by partial sciatic nerve ligation. In these 2 models, heat hyperalgesia was virtually unchanged. SNC80, a delta agonist administered either systemically (complete Freund adjuvant and sciatic nerve ligation) or into a paw (sciatic nerve ligation), reduced thermal hyperalgesia and mechanical allodynia in control mice. However, these analgesic effects were absent in conditional mutant mice. In conclusion, this study reveals the existence of delta opioid receptor-mediated mechanisms, which operate at the level of Na(V)1.8-positive nociceptive neurons. Delta receptors in these neurons tonically inhibit mechanical hypersensitivity in both inflammatory and neuropathic pain, and they are essential to mediate delta opioid analgesia under conditions of persistent pain. This delta receptor population represents a feasible therapeutic target to alleviate chronic pain while avoiding adverse central effects. The conditional knockout of delta-opioid receptor in primary afferent Na(V)1.8 neurons augmented mechanical allodynia in persistent pain models and abolished

  5. Mobilization of Arsenic in Groundwater of Holocene Delta, Indian Segment

    Science.gov (United States)

    Chatterjee, D.

    2007-12-01

    Recent incidences of high arsenic exposure from drinking water and human suffering in SE Asia notably in Bengal Delta Plain (BDP) appear to be quite different from the global scenario. The source of arsenic in groundwater of BDP is considered to be geogenic and mostly restricted to Holocene sediments. Several models (oxidation of As-rich pyrite, reductive dissolution of Fe(III)-Fe(II) systems, anion exchange of sorbed As mostly phosphate) have been put forward. However, the models have their own weakness and the paper deals with such discrepancies to focus the arsenic sourcing (primary, secondary and tertiary), release mechanism and mobilization in Holocene deltas. The paper also deals with groundwater quality and (hydro) chemistry vis-a-vis alluvial Holocene sediment. The stratigraphic profiling indicates that the shallow aquifers (sanitation, surface water bodies, land use and sanitation coupled with eco-system) are identified and most important is sanitation where groundwater arsenic concentration is highest (up to 1180 mg/L) among the different local situation. Arsenic hotspots are identified as a multi-level phenomena and unveiled greater complexities at a deeper level. Morphology and sediment profiling of BDP deltas are influencing arsenic sourcing where sandy useable aquifers are identified with overbank deposits rich in arsenic host environment. Shallow aquifers ( 5-70 m) are often enriched with DOC ( range- 1.2- 7.0 mg/L) where as deep aquifers ( 100- 304 m ) are relatively containing low amount of DOC ( 0.4- 1.9 mg/L). This reflects the influence of local processes at shallow depths where oxidative as well as microbial degeneration of carbon sink is playing crucial role in arsenic mobilization. This also suggests that the break down of organic matter is the principal process in the shallow reducing aquifers with high/low arsenic along with high / low - coupled redox sensitive species and DOC. The presence of DOC in shallow aquifers also indicates that

  6. Analog circuit design structured mixed-mode design, multi-bit sigma-delta converters, short range RF circuits

    CERN Document Server

    van Roermund, Arthur

    2007-01-01

    Preface. Part I: Structured Mixed-Mode Design. Introduction. Structured Oscillator Design; C. Verhoeven, A. van Staveren. Systematic Design of High-frequency gm-C Filters; E. Lauwers, G. Gielen. Structured LNA Design; E.H. Nordholt. High-Level Simulation and Modeling Tools for Mixed-Signal Front-ends of Wireless Systems; P. Wambacq, et al. Structured Simulation-Based Analog Design Synthesis; R.A. Rutenbar. Structured Analog layout Design; K. Lampaert. Part II: Multi-Bit Sigma Delta Converters. Introduction. Architecture Considerations for Multi-Bit SigmaDelta ADCs; T. Brooks. Multirate Sigma-Delta Modulators, an Alternative to Multibit; F. Colodro, A. Torralba. Circuit Design Aspects of Multi-Bit Delta-Sigma Converters; Y. Geerts, et al. High-speed Digital to Analog Converter Issues with Applications to Sigma Delta Modulators; K. Doris, et al. Correction-Free Multi-Bit Sigma-Delta Modulators for ADSL; R. del Rio, et al. Sigma Delta Converters in Wireline Communications; A. Wiesbauer, et al. Part III: Short Ra...

  7. DELTA-DIESEL ENGINE LIGHT TRUCK APPLICATION Contract DE-FC05-97OR22606 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hakim, Nabil Balnaves, Mike

    2003-05-27

    DELTA Diesel Engine Light Truck Application End of Contract Report DE-FC05-97-OR22606 EXECUTIVE SUMMARY This report is the final technical report of the Diesel Engine Light Truck Application (DELTA) program under contract DE-FC05-97-OR22606. During the course of this contract, Detroit Diesel Corporation analyzed, designed, tooled, developed and applied the ''Proof of Concept'' (Generation 0) 4.0L V-6 DELTA engine and designed the successor ''Production Technology Demonstration'' (Generation 1) 4.0L V-6 DELTA engine. The objectives of DELTA Program contract DE-FC05-97-OR22606 were to: Demonstrate production-viable diesel engine technologies, specifically intended for the North American LDT and SUV markets; Demonstrate emissions compliance with significant fuel economy advantages. With a clean sheet design, DDC produced the DELTA engine concept promising the following attributes: 30-50% improved fuel economy; Low cost; Good durability and reliability; Acceptable noise, vibration and harshness (NVH); State-of-the-art features; Even firing, 4 valves per cylinder; High pressure common rail fuel system; Electronically controlled; Turbocharged, intercooled, cooled EGR; Extremely low emissions via CLEAN Combustion{copyright} technology. To demonstrate the engine technology in the SUV market, DDC repowered a 1999 Dodge Durango with the DELTA Generation 0 engine. Fuel economy improvements were approximately 50% better than the gasoline engine replaced in the vehicle.

  8. High speed and wide bandwidth delta-sigma ADCs

    CERN Document Server

    Bolatkale, Muhammed; Makinwa, Kofi A A

    2014-01-01

    This book describes techniques for realizing wide bandwidth (125MHz) over-sampled analog-to-digital converters (ADCs) in nanometer-CMOS processes.  The authors offer a clear and complete picture of system level challenges and practical design solutions in high-speed Delta-Sigma modulators.  Readers will be enabled to implement ADCs as continuous-time delta-sigma (CT∆Σ) modulators, offering simple resistive inputs, which do not require the use of power-hungry input buffers, as well as offering inherent anti-aliasing, which simplifies system integration. The authors focus on the design of high speed and wide-bandwidth ΔΣMs that make a step in bandwidth range which was previously only possible with Nyquist converters. More specifically, this book describes the stability, power efficiency, and linearity limits of ΔΣMs, aiming at a GHz sampling frequency.   • Provides overview of trends in Wide Bandwidth and High Dynamic Range analog-to-digital converters (ADCs); • Enables the design of a wide band...

  9. The leading-edge vortex of swift wing-shaped delta wings

    Science.gov (United States)

    Muir, Rowan Eveline; Arredondo-Galeana, Abel; Viola, Ignazio Maria

    2017-08-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing.

  10. The leading-edge vortex of swift wing-shaped delta wings

    Science.gov (United States)

    Muir, Rowan Eveline; Arredondo-Galeana, Abel

    2017-01-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing. PMID:28878968

  11. Effects of acute oral Delta9-tetrahydrocannabinol and standardized cannabis extract on the auditory P300 event-related potential in healthy volunteers.

    Science.gov (United States)

    Roser, Patrik; Juckel, Georg; Rentzsch, Johannes; Nadulski, Thomas; Gallinat, Jürgen; Stadelmann, Andreas M

    2008-08-01

    Reduced amplitudes of auditory evoked P300 are a robust finding in schizophrenic patients, indicating deficient attentional resource allocation and active working memory. Delta9-Tetrahydrocannabinol (Delta9-THC), the main active constituent of Cannabis sativa, has been known to acutely impair cognitive abilities in several domains, particularly in memory and attention. Given the psychotic-like effects of Delta9-THC, a cannabinoid hypothesis of schizophrenia has been proposed. This prospective, double-blind, placebo-controlled cross-over study investigated the acute effects of cannabinoids on P300 amplitude in 20 healthy volunteers (age 28.2+/-3.1 years, 10 male) by comparing Delta9-THC and standardized cannabis extract containing Delta9-THC and cannabidiol (CBD). P300 waves were recorded during a choice reaction task. As expected, Delta9-THC revealed a significant reduction of P300 amplitude at midline frontal, central, and parietal electrodes. CBD has been known to abolish many of the psychotropic effects of Delta9-THC, but, unexpectedly, failed to demonstrate a reversal of Delta9-THC-induced P300 reduction. Moreover, there were no correlations between cannabinoid plasma concentrations and P300 parameters. These data suggest that Delta(9)-THC may lead to acute impairment of attentional functioning and working memory. It can be speculated whether the lack of effect of CBD may be due to an insufficient dose used or to an involvement of neurotransmitter systems in P300 generation which are not influenced by CBD.

  12. Efficient retention of mud drives land building on the Mississippi Delta plain

    Science.gov (United States)

    Esposito, Christopher R.; Shen, Zhixiong; Törnqvist, Torbjörn E.; Marshak, Jonathan; White, Christopher

    2017-07-01

    Many of the world's deltas - home to major population centers - are rapidly degrading due to reduced sediment supply, making these systems less resilient to increasing rates of relative sea-level rise. The Mississippi Delta faces some of the highest rates of wetland loss in the world. As a result, multibillion dollar plans for coastal restoration by means of river diversions are currently nearing implementation. River diversions aim to bring sediment back to the presently sediment-starved delta plain. Within this context, sediment retention efficiency (SRE) is a critical parameter because it dictates the effectiveness of river diversions. Several recent studies have focused on land building along the open coast, showing SREs ranging from 5 to 30 %. Here we measure the SRE of a large relict crevasse splay in an inland, vegetated setting that serves as an appropriate model for river diversions. By comparing the mass fraction of sand in the splay deposit to the estimated sand fraction that entered it during its life cycle, we find that this mud-dominated sediment body has an SRE of ≥ 75 %, i.e., dramatically higher than its counterparts on the open coast. Our results show that transport pathways for mud are critical for delta evolution and that SRE is highly variable across a delta. We conclude that sediment diversions located in settings that are currently still vegetated are likely to be the most effective in mitigating land loss and providing long-term sustainability.

  13. Topical delta 9-tetrahydrocannabinol and aqueous dynamics in glaucoma.

    Science.gov (United States)

    Merritt, J C; Perry, D D; Russell, D N; Jones, B F

    1981-01-01

    Systemic delta 9-tetrahydrocannabinol (THC), administered either by smoking marihuana or as synthetic THC in soft gelatin capsules, lowers ocular tension in various glaucomas, but at the expense of significant decreases in systolic blood pressure. Topical THC in light mineral oil vehicles, though effective in laboratory animals, was not shown effective in 0.05 and 0.1% topical solutions when administered to six subjects with primary open-angle glaucoma in a randomized, balanced, double-masked protocol. Light mineral oil, which has an affinity for corneal epithelium, is an optimum vehicle for administering drugs whose mechanisms of action are systemic rather than local within the eye. Further glaucoma research should therefore proceed with marihuanas containing insignificant levels of THC (less than 0.4%) and with various local delivery systems of the ocular-active cannabinoid found in Cannabis sativa.

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

    Science.gov (United States)

    Rottman, James W.; Stansby, Peter K.

    1993-01-01

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

  15. Determination of the attenuation due to the treatment table according to the angle of gantry for system treatments verification Delta4; Dterminacion de la atenuacion debida a la mesa de tratamiento en funcion del angulo de Cantry para el sistema de verificacion de tratamientos Delta4

    Energy Technology Data Exchange (ETDEWEB)

    Linares Doblado, R.; Mateo Rodriguez, B.; Perucha Ortega, M.

    2013-07-01

    The optimal solution to the problem of absorption into the table would be to incorporate it into the system of planning as one structure more, but not all planners incorporate this functionality. As an alternative solution, approximate, this paper evaluates through measures in the system mentioned effect, with the aim of obtaining a table of absorption vs. angle of gantry, for different field sizes that will be used to correct the dose values recorded by the QA system. Research on the effect of the corrections in the histograms of dose and gamma. (Author)

  16. Biogeochemical features of aquatic plants in the Selenga River delta

    Science.gov (United States)

    Shinkareva, Galina; Lychagin, Mikhail

    2014-05-01

    The Selenga River system provides more than a half of the Lake Baikal total inflow. The river collects a significant amount of pollutants (e.g. heavy metals) from the whole basin. These substances are partially deposited within the Selenga delta, and partially are transported further to the lake. A generous amount of aquatic plants grow in the delta area according to its favorable conditions. This vegetation works as a specific biofilter. It accumulates suspended particles and sorbs some heavy metals from the water. The study aimed to reveal the species of macrophytes which could be mostly important for biomonitoring according to their chemical composition. The field campaign took place in the Selenga River delta in July-August of 2011 (high water period) and in June of 2012 (low water period). 14 species of aquatic plants were collected: water starwort Callitriche hermaphroditica, small yellow pond lily Nuphar pumila, pondweeds Potamogeton crispus, P. pectinatus, P. friesii, broadleaf cattail Typha latifolia, hornwort or coontail Ceratophyllum demersum, arrowhead Sagittaria natans, flowering rush (or grass rush) Butomus umbellatus, reed Phragmites australis, parrot's feather Myriophyllum spicatum, the common mare's tail Hippuris vulgaris, Batrachium trichophyllum, canadian waterweed Elodea canadensis. The samples were dried, grinded up and digested in a mixture of HNO3 and H2O2. The chemical composition of the plant material was defined using ICP-MS and ICP-AES methods. Concentrations of Fe, Mn, Cr, Ni, Cu, B, Zn, V, Co, As, Mo, Pb, and U were considered. The study revealed that Potamogeton pectinatus and Myriophyllum spicatum concentrate elements during both high and low water periods. Conversely the Butomus umbellatus and Phragmites australis contain small amount of heavy metals. The reed as true grasses usually accumulates fewer amounts of elements than other macrophytes. To compare biogeochemical specialization of different species we suggest to use

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

    Science.gov (United States)

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

    2015-04-01

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

  18. Water quality in the Okavango Delta

    African Journals Online (AJOL)

    2010-03-12

    Mar 12, 2010 ... 2009 (Fig. 4). Measurements had been taken at several points from Mohembo to Maun and Lake Ngami in the downstream end of the Delta. pH. The pH of an aquatic ... tion of the aquatic ecosystem (Smith et al., 1986). The pH of ... DO in the water was attributed to the decomposition of organic matter or ...

  19. (-)-delta-N-normethylskytanthine from Tecoma arequipensis.

    Science.gov (United States)

    Harris, G H; Fixman, E C; Stermitz, F R; Castedo, L

    1988-01-01

    Bark of Tecoma arequipensis yielded the major alkaloidal component (-)-delta-N-normethylskytanthine whose structure was proven by X-ray diffraction analysis of the N-thiourea derivative. The stereochemistry of 1 at all four centers was enantiomeric with that of skytanthine previously reported from Tecoma stans and Skytanthus acutus. Gc-ms of the crude base fraction indicated the presence of several related alkaloids as very minor constituents.

  20. Nucleon and delta masses in QCD

    OpenAIRE

    Rafecas López, María Magdalena; Vento Torres, Vicente

    1992-01-01

    Using the positivity of the path integral measure of $QCD$ and defining a structure for the quark propagator in a background field according to the fluxon scenario for confinement, we calculate and compare the correlators for nucleon and delta. From their shape we elucidate about the origin of their mass difference, which in our simplified scenario is due to the tensor structure in the propagator. This term arises due to a dynamical mechanism which is responsible simultaneously for confinemen...

  1. Unsteady Aerodynamics of Nonslender Delta Wings

    OpenAIRE

    Gursul, I; Gordnier, R; Visbal, M

    2005-01-01

    Unsteady aerodynamics of nonslender delta wings, covering topics of shear layer instabilities, structure of nonslender vortices, breakdown, maneuvering wings, and fluid/structure interactions, are reviewed in this paper. Vortical flows develop at very low angles of attack, and form close to the wing surface. This results in strong interactions with the upper-surface boundary layer and in a pronounced dependence of the flow structure on Reynolds number. Vortex breakdown is observed to be much ...

  2. Pole Positions of the Delta(1232) Resonance

    OpenAIRE

    Kelabi, Mohamed E.

    2006-01-01

    The phase shift of pion nucleon elastic scattering D33, corresponding to isospin I=3/2 and angular momentum J=3/2, has been parameterized over the range 1100 < W < 1375 MeV, using the single channel p Pi+ data from CNS-DAC. By employing our four parameters formula, the pole positions of corresponding to the Delta(1232) resonance are then identified.

  3. Petroleum system elements within the Late Cretaceous and Early Paleogene sediments of Nigeria's inland basins: An integrated sequence stratigraphic approach

    Science.gov (United States)

    Dim, Chidozie Izuchukwu Princeton; Onuoha, K. Mosto; Okeugo, Chukwudike Gabriel; Ozumba, Bertram Maduka

    2017-06-01

    Sequence stratigraphic studies have been carried out using subsurface well and 2D seismic data in the Late Cretaceous and Early Paleogene sediments of Anambra and proximal onshore section of Niger Delta Basin in the Southeastern Nigeria. The aim was to establish the stratigraphic framework for better understanding of the reservoir, source and seal rock presence and distribution in the basin. Thirteen stratigraphic bounding surfaces (consisting of six maximum flooding surfaces - MFSs and seven sequence boundaries - SBs) were recognized and calibrated using a newly modified chronostratigraphic chart. Stratigraphic surfaces were matched with corresponding foraminiferal and palynological biozones, aiding correlation across wells in this study. Well log sequence stratigraphic correlation reveals that stratal packages within the basin are segmented into six depositional sequences occurring from Late Cretaceous to Early Paleogene age. Generated gross depositional environment maps at various MFSs show that sediment packages deposited within shelfal to deep marine settings, reflect continuous rise and fall of sea levels within a regressive cycle. Each of these sequences consist of three system tracts (lowstand system tract - LST, transgressive system tract - TST and highstand system tract - HST) that are associated with mainly progradational and retrogradational sediment stacking patterns. Well correlation reveals that the sand and shale units of the LSTs, HSTs and TSTs, that constitute the reservoir and source/seal packages respectively are laterally continuous and thicken basinwards, due to structural influences. Result from interpretation of seismic section reveals the presence of hanging wall, footwall, horst block and collapsed crest structures. These structural features generally aid migration and offer entrapment mechanism for hydrocarbon accumulation. The combination of these reservoirs, sources, seals and trap elements form a good petroleum system that is viable

  4. Understanding delta-sigma data converters

    CERN Document Server

    Pavan, Shanti; Temes, Gabor C

    2017-01-01

    This new edition introduces novel analysis and design techniques for delta-sigma (ΔΣ) converters in physical and conceptual terms, and includes new chapters that explore developments in the field over the last decade. This book explains the principles and operation of delta-sigma analog-to-digital converters (ADCs) in physical and conceptual terms in accordance with the most recent developments in the field. The interest of ΔΣ converter designers has shifted significantly over the past decade, due to many new applications for data converters at the far ends of the frequency spectrum. Continuous-time delta-sigma A/D converters with GHz clocks, of both lowpass and bandpass types, are required for wireless applications. At the other extreme, multiplexed ADCs with very narrow (sometimes 10 Hz wide) signal bandwidths, but very high accuracy are needed in the interfaces of biomedical and environmental sensors. To reflect the changing eeds of designers, the second edition includes significant new material on bo...

  5. Sea level rise and land loss in the Nile Delta | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-06-09

    Jun 9, 2016 ... IDRC-funded researchers have identified coastal areas in the Nile Delta that may be vulnerable to sea level rise using Geographical Information Systems (GIS). Results indicate that significant land loss may occur in that region by 2100. Using the most recent predictions of sea level rise, total coastal land ...

  6. Global and local governance of shrimp farming in the Mekong Delta, Vietnam

    NARCIS (Netherlands)

    Tran Thi Thu, H.

    2012-01-01

    The Mekong Delta is one of seven ecological regions in Vietnam where aquaculture and shrimp products are internationally traded and the shrimp farmers are firmly embedded in a global system of production and trade. The growth of shrimp aquaculture, in addition to population growth and higher levels

  7. Operationalising a resilience approach to adapting an urban delta to uncertain climate changes

    NARCIS (Netherlands)

    Wardekker, J.A.|info:eu-repo/dai/nl/306644398; de Jong, A.|info:eu-repo/dai/nl/326795960; Knoop, J.M.; van der Sluijs, J.P.|info:eu-repo/dai/nl/073427489

    2010-01-01

    Climate change may pose considerable challenges to coastal cities, particularly in low-lying urban deltas. Impacts are, however, associated with substantial uncertainties. This paper studies an uncertainty-robust adaptation strategy: strengthening the resilience of the impacted system. This approach

  8. Decision trees for farm management on acid sulfate soils, Mekong Delta, Vietnam

    NARCIS (Netherlands)

    Quang Tri, Le; Mensvoort, van M.E.F.

    2004-01-01

    Our study shows how farmers in the Mekong Delta, Viet Nam, have developed new cropping systems and management practices to overcome the constraints of their land. Decision trees for land evaluation at farm level, combining farmer and expert knowledge, were developed to support management decisions

  9. Composition, biomass and structure of mangroves within the Zambezi River Delta

    Science.gov (United States)

    Carl C. Trettin; Christina E. Stringer; Stan Zarnoch

    2015-01-01

    We used a stratified random sampling design to inventory the mangrove vegetation within the Zambezi River Delta, Mozambique, to provide a basis for estimating biomass pools. We used canopy height, derived from remote sensing data, to stratify the inventory area, and then applied a spatial decision support system to objectively allocate sample plots among five...

  10. Rice-freshwater prawn (Macrobrachium rosenbergii) farms in the Mekong Delta, Vietnam

    OpenAIRE

    Quang, Nguyen

    1993-01-01

    Aquaculture in riceland has been practiced in Mekong Delta, Vietnam for a long time and integrated rice-freshwater prawn (Macrobrachium rosenbergii) farming has become more and more popular. The integrated farming systems developed and practiced by farmers in the area to produce more food and more cash crops are presented and discussed.

  11. Livelihood Capabilities and Pathways of Shrimp Farmers in the Mekong Delta, Vietnam

    NARCIS (Netherlands)

    Tran Thi Phung Ha, Ha; Dijk, van J.W.M.; Bosma, R.H.; Sinh, L.X.

    2013-01-01

    Shrimp farming is a major livelihood activity in the Mekong Delta in the southernmost part of Vietnam. The Vietnamese government has promoted shrimp farming as a way to reduce poverty, provide employment opportunities and increase exports to support economic development. The shrimp farming system,

  12. HABITAT ASSESSMENT USING A RANDOM PROBABILITY BASED SAMPLING DESIGN: ESCAMBIA RIVER DELTA, FLORIDA

    Science.gov (United States)

    Smith, Lisa M., Darrin D. Dantin and Steve Jordan. In press. Habitat Assessment Using a Random Probability Based Sampling Design: Escambia River Delta, Florida (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems...

  13. CCR5 delta32, matrix metalloproteinase-9 and disease activity in multiple sclerosis

    DEFF Research Database (Denmark)

    Sellebjerg, Finn; Madsen, Hans O; Jensen, Claus V

    2000-01-01

    Chemokines and matrix metalloproteinases (MMPs) appear to be crucial in leukocyte recruitment to the central nervous system in multiple sclerosis (MS). CCR5 delta32, a truncated allele of the CC chemokine receptor CCR5 gene encoding a non-functional receptor, did not confer protection from MS. CCR5...

  14. Optimal Vibration Control for Half-Car Suspension on In-Vehicle Networks in Delta Domain

    Directory of Open Access Journals (Sweden)

    Jing Lei

    2013-01-01

    Full Text Available The paper explores the optimal vibration control design problem for a half-car suspension working on in-vehicle networks in delta domain. First, the original suspension system with ECU-actuator delay and sensor-ECU delay is modeled. By using delta operators, the original system is transformed into an associated sampled-data system with time delays in delta domain. After model transformation, the sampled-data system equation is reduced to one without actuator delays and convenient to calculate the states with nonintegral time delay. Therefore, the sampled-data optimal vibration control law can be easily obtained deriving from a Riccati equation and a Stein equation of delta domain. The feedforward control term and the control memory terms designed in the control law ensure the compensation for the effects produced by disturbance and actuator delay, respectively. Moreover, an observer is constructed to implement the physical realizability of the feedforward term and solve the immeasurability problem of some state variables. A half-car suspension model with delays is applied to simulate the responses through the designed controller. Simulation results illustrate the effectiveness of the proposed controller and the simplicity of the designing approach.

  15. THE 2011 PERIASTRON PASSAGE OF THE Be BINARY {delta} Scorpii

    Energy Technology Data Exchange (ETDEWEB)

    Miroshnichenko, A. S. [Department of Physics and Astronomy, University of North Carolina at Greensboro, Greensboro, NC 27402-6170 (United States); Pasechnik, A. V. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-21500 Puekkioe (Finland); Manset, N. [CFHT Corporation, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Carciofi, A. C. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo (Brazil); Rivinius, Th. [European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19 (Chile); Stefl, S. [ESO/ALMA, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Gvaramadze, V. V. [Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij Pr. 13, Moscow 119992 (Russian Federation); Ribeiro, J. [Observatorio do Instituto Geografico do Exercito, Lisboa (Portugal); Fernando, A. [ATALAIA.org Group, Lisboa (Portugal); Garrel, T. [Observatoire de Juvignac, 19 avenue de Hameau du Golf F-34990, Juvignac (France); Knapen, J. H. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Buil, C. [Castanet Tolosan Observatory, 6 place Clemence Isaure F-31320 Castanet Tolosan (France); Heathcote, B. [Barfold Observatory, Glenhope, Victoria 3444 (Australia); Pollmann, E. [Emil-Nolde-Str. 12, D-51375, Leverkusen (Germany); Mauclaire, B. [Observatoire du Val d' Arc, route de Peynier F-13530, Trets (France); Thizy, O. [Shelyak Instruments, 1116 route de Chambery, F-38330, Saint-Ismier (France); Martin, J. [Barber Research Observatory, Department of Physics and Astronomy, University of Illinois-Springfield, IL 62703 (United States); Zharikov, S. V. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. Postal 877, Ensenada, 22800, Baja California (Mexico); Okazaki, A. T. [Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan); and others

    2013-04-01

    We describe the results of the world-wide observing campaign of the highly eccentric Be binary system {delta} Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 {+-} 0.0005 yr. Fitting of the He II 4686 A line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9-day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 M{sub Sun }) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the H{alpha} line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 R{sub Sun }. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that {delta} Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40 Degree-Sign with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations.

  16. Spatial variability of multi-controlled aeolian supersurfaces in central-erg and marine-erg-margin systems

    NARCIS (Netherlands)

    Rodríguez-López, J.P.; Meléndez, N.; de Boer, P.L.; Soria, A.R.; Liesa, C.L.

    2013-01-01

    During the Albian Iberia was under the influence of the Northern-Hemisphere Hot Arid Belt favouring the development of an extensive sandy desert system with a marine-erg margin where prograding aeolian dunes interacted with Tethyan waters. The interplay of different controls, such as synsedimentary

  17. Optimization and Design of a Low Power Switched Current A/D Sigma-Delta-Modulator for Voice Band Applications

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur

    1998-01-01

    This paper presents a third order switched current sigma delta-modulator. The modulator is optimized at the system level for minimum power consumption by careful design of the noise transfer function. A thorough noise analysis of the cascode type current copiers used to implement the modulator...... to internal clamping in the integrators and proper scaling the modulator shows excellent stability properties. In order to compare the performance of the modulator presented in this paper to other sigma delta-modulators two figure-of-merits (FOMs) are proposed. From these figure-of-merits it is found...... that the performance of the modulator presented in this paper is significantely higher than the perforamce of other switched current sigma delta-modulators reported. Also, the figure-of-merits show that the performance is comparable to the performance of reported switched capacitor sigma delta-modulators....

  18. A new seamless, high-resolution digital elevation model of the San Francisco Bay-Delta Estuary, California

    Science.gov (United States)

    Fregoso, Theresa; Wang, Rueen-Fang; Ateljevich, Eli; Jaffe, Bruce E.

    2017-06-14

    Climate change, sea-level rise, and human development have contributed to the changing geomorphology of the San Francisco Bay - Delta (Bay-Delta) Estuary system. The need to predict scenarios of change led to the development of a new seamless, high-resolution digital elevation model (DEM) of the Bay – Delta that can be used by modelers attempting to understand potential future changes to the estuary system. This report details the three phases of the creation of this DEM. The first phase took a bathymetric-only DEM created in 2005 by the U.S. Geological Survey (USGS), refined it with additional data, and identified areas that would benefit from new surveys. The second phase began a USGS collaboration with the California Department of Water Resources (DWR) that updated a 2012 DWR seamless bathymetric/topographic DEM of the Bay-Delta with input from the USGS and modifications to fit the specific needs of USGS modelers. The third phase took the work from phase 2 and expanded the coverage area in the north to include the Yolo Bypass up to the Fremont Weir, the Sacramento River up to Knights Landing, and the American River up to the Nimbus Dam, and added back in the elevations for interior islands. The constant evolution of the Bay-Delta will require continuous updates to the DEM of the Delta, and there still are areas with older data that would benefit from modern surveys. As a result, DWR plans to continue updating the DEM.

  19. Holocene palaeoDEMs for lowland coastal and delta plain landscape reconstructions

    Science.gov (United States)

    Cohen, Kim M.; Koster, Kay; Pierik, Harm-Jan; Van der Meulen, Bas; Hijma, Marc; Schokker, Jeroen; Stafleu, Jan

    2017-04-01

    Geological mapping of Holocene deposits of coastal plains, such as that of The Netherlands can reach high resolution (dense population, diverse applied usage) and good time control (14C dating, archaeology). The next step is then to create time sliced reconstructions for stages in the Holocene, peeling of the subrecent and exposing past relief situation. This includes winding back the history of sea-level rise and delta progradation etc. etc. So far, this has mainly be done as 2D series of landscape maps, or as sea-level curve age-depth plots. In the last decade, academic and applied projects at Utrecht University, TNO Geological Survey of The Netherlands and Deltares have developed palaeoDEMs for the Dutch low lands, that are a third main way of showing coastal plain evolution. Importantly, we produce two types of palaeoDEMs: (1) geological surface mapping using deposit contacts from borehole descriptions (and scripted 3D processing techniques - e.g. Van der Meulen et al. 2013) and (2) palaeogroundwater surfaces, using sea-level and inland water-level index-points (and 3D kriging interpolations - e.g. Koster et al. 2016). The applications for the combined palaeoDEMs range from relative sea-level rise mapping and assessment of variation in rate of GIA across the coastal plain, to quantification of soft soil deformation, to analysis of pre-embankment extreme flood levels. Koster, K., Stafleu, J., & Cohen, K.M. (2016). Generic 3D interpolation of Holocene base-level rise and provision of accommodation space, developed for the Netherlands coastal plain and infilled palaeovalleys. Basin Research. DOI 10.1111/bre.12202 Van der Meulen, M.J., Doornenbal, J.C., Gunnink, J.L., Stafleu, J., Schokker, J., Vernes, R.W., Van Geer, F.C., Van Gessel, S.F., Van Heteren, S., Van Leeuwen, R.J.W. & Bakker, M.A.J. (2013). 3D geology in a 2D country: perspectives for geological surveying in the Netherlands. Netherlands Journal of Geosciences, 92, 217-241. DOI 10.1017/S0016774600000184

  20. Kajian Peran Lembaga dan Kearifan Masyarakat dalam Pengelolaan Ekosistem Hutan Mangrove secara Terpadu di Delta Mahakam

    Directory of Open Access Journals (Sweden)

    Lenny Dianawati

    2016-09-01

    penelitian dan pembahasan yang telah dilakukan, didapatkan kesimpulan bahwa: (1 Pengelolaan hutan mangrove di Delta Mahakam sendiri melibatkan peran dari masyarakat, swasta, dan pemerintah. Pihak pemerintah yang terkait adalah Badan Lingkungan Hidup Provinsi Kalimantan Timur, Dinas Kehutanan Provinsi Kalimantan Timur, dan Dinas Perikanan dan Kelautan Provinsi Kalimantan Timur. Pihak masyarakat dibedakan menjadi masyarakat asli dan pendatang. Masyarakat asli yang bermukim di sekitar hutan mangrove Delta Mahakam melakukan kegiatan perawatan, penanaman, dan pembersihan lingkungan hutan bakau. Sementara masyarakat pendatang yang merupakan pengusaha tambak memberikan sejumlah dana untuk dikelola pemerintah guna memperbaiki kondisi hutan mangrove Delta Mahakam yang rusak akibat kegiatan usaha tambak. (2 Integrasi antara pemerintah dengan masyarakat asli maupun masyarakat pendatang sebagi pengusaha tambak diperlukan guna menjamin terselenggaranya perlindungan, pelestarian, dan pemanfaatan ekosistem mangrove sebagai sumberdaya di wilayah pesisir, system penyangga kehidupan, dan kekayaan alam yang bernilai tinggi.   ABSTRACT At this time the mangrove forest in Delta Mahakam region heavily damaged area of 24 035 hectares (49.44% of the mangrove area in the Delta Mahakam, covering an area of 41 608 hectares lightly damaged (27.78%, and is still in a state of an area of 34 089 hectares only good (22.7%.Such damage ismostlycaused bythe opening of mangrove forests for aquaculture enterprises bypeople from outside the region of East Kalimantan. Law No.41 of 1999 mandates that the Forest Service has the authority to preserve the mangrove forests in the waters include waters n the Delta Mahakam. On the other hand, the Law Number31of 2004 on Fisheries requires that fishery management area ofthe Republic of Indonesia for fishing or aquaculture, include rivers, lakes, reservoirs, marshes and other stagnant water that can be cultivated and land fish farming potential in the territory of the

  1. An Evolutionary Perspective on Global Vegetation \\delta15N Co-variance With Average Annual Precipitation

    Science.gov (United States)

    Sechrest, W.; Billmark, K. A.; Shields, L. G.; Swap, R. J.; Macko, S. A.

    2001-12-01

    Recent regional transect studies have shown a significant negative relationship between the \\delta15N value of vegetation and the mean annual precipitation. \\delta15N values provide an indication of the source nitrogen utilized by the plant owing to differential fractionations from biological and chemical processes. The fact that such a relationship exists across a variety of systems is surprising given the abundance of global plant species and the complexity of the nitrogen cycle. This observed pattern suggests that there may be some biological controls on plant utilization of nitrogen that are linked to available water. After observing this relationship in samples collected as a part of the Southern African Regional Science Initiative (SAFARI 2000), we have found that this relationship holds on a global scale for published values of \\delta15N. The critical question remains; is this relationship a result of shared characteristics of related species, or more broadly is there an evolutionary reason for this relationship? Since the \\delta15N values varied with rainfall, we hypothesize that the photosynthetic pathway utilized by plants play a role in this pattern. For example, plants that have evolved C4 metabolism, in other words, plants that have evolved mechanisms to allow for utilization of nutrients in a way more independent of available water than their C3 metabolizing counterparts, may exhibit different \\delta15N with respect to our original relationship. The data collected in conjunction with SAFARI 2000 confirms this hypothesis and as a result we have used modern phylogenetic techniques (using taxonomic information as a surrogate for true phylogenetic relationships between the included plant species) to test whether evolutionary history has played a role in the \\delta15N pattern. We anticipate that by using multidisciplinary tools this study will greatly advance ongoing research in the areas of nitrogen dynamics and vegetative biogeochemical cycling.

  2. Understanding Migration as an Adaptation in Deltas Using a Bayesian Network Model

    Science.gov (United States)

    Lázár, A. N.; Adams, H.; de Campos, R. S.; Mortreux, C. C.; Clarke, D.; Nicholls, R. J.; Amisigo, B. A.

    2016-12-01

    Deltas are hotspots of high population density, fertile lands and dramatic environmental and anthropogenic pressures and changes. Amongst other environmental factors, sea level rise, soil salinization, water shortages and erosion threaten people's livelihoods and wellbeing. As a result, there is a growing concern that significant environmental change induced migration might occur from these areas. Migration, however, is already happening for economic, education and other reasons (e.g. livelihood change, marriage, planned relocation, etc.). Migration hence has multiple, interlinked drivers and depending on the perspective, can be considered as a positive or negative phenomenon. The DECCMA project (Deltas, Vulnerability & Climate Change: Migration & Adaptation) studies migration as part of a suite of adaptation options available to the coastal populations in the Ganges delta in Bangladesh, the Mahanadi delta in India and the Volta delta in Ghana. It aims to develop a holistic framework of analysis that assesses the impact of climate and environmental change on the migration patterns of these areas. This assessment framework will couple environmental, socio-economics and governance dimensions in an attempt to synthesise drivers and barriers and allow testing of plausible future scenarios. One of the integrative methods of DECCMA is a Bayesian Belief Network (BBN) model describing the decision-making of a coastal household. BBN models are built on qualitative and quantitative observations/expert knowledge and describe the probability of different events/responses etc. BBN models are especially useful to capture uncertainties of large systems and engaging with stakeholders. The DECCMA BBN model is based on household survey results from delta migrant sending areas. This presentation will describe model elements (livelihood sensitivity to climate change, local and national adaptation options, household characteristics/attitude, social networks, household decision) and

  3. THE RURAL TOURISM IN DANUBE DELTA

    Directory of Open Access Journals (Sweden)

    Ionica SOARE

    2014-06-01

    Full Text Available Purpose - the purpose of this paper is to evaluate the rural areas has market size and forecast its development as an economic activity. The present paper aims at analyzing the rural areas has in Danube Delta. In an enviable BAs which have responsibility for their particular isolated, such as the Danube Delta and the Danube that used, fishing and rural areas has the main activities that provide jobs and income sources for local populations. Design/methodology/approach - A survey was administered to customers’ rural hostel accommodation in Danube Delta. Descriptive statistics method was mainly adopted to calculate the mean with standard deviation of entry assumes variable, and to examine the different levels of consumers' awareness. The index values of product familiarity, the ratio between entries assumes product's familiarity value and the average value. Findings - the research results show hash has rural consumers have different perception and accomplished through behaviour. The information channels of brand hash mainly from friends, relatives and neighbours, so word of mouth spreading is very important for a brand. Women show a higher sensitivity in health and are currently operating the propensity than referred to follow the recommendations for nutrition. Research limitations/implications - This item is intended to synthesize developments and challenges," on June 13th rural market growth has. The results of this paper should be considered tentatively until has also features replicated by larger has rural consumers. Originality/value - members of rural areas has consumer's behavior would improve marketing and the development of rural areas has products, in order to reduce consumer confusion.

  4. Delta robots – robots for high speed manipulation

    OpenAIRE

    Poppeová, Viera; Uríček, Juraj; Bulej, Vladimír; Šindler, Peter

    2011-01-01

    This paper is oriented to parallel kinematic robots definition, description of their specific application, comparison of robots made by different producers and determination of velocity and acceleration parameters, kinematic analysis – inverse and forward kinematic. It brings information about development of Delta robots at Academia, including the University of Žilina and Delta robots in the market. Two models of Delta robots called M-1iA and M-3iA have been developed by FANUC Robotics during...

  5. Sigma Delta Signal Processing on Via-Configurable Arrays

    Science.gov (United States)

    2016-03-31

    Sigma Delta Signal Processing on Via-Configurable Arrays Jim Kemerling Triad Semiconductor, Inc. Winston-Salem, NC 27103 Abstract: Sigma -Delta...Mask Programmable Analog Array; Mixed-Signal ASIC; Sigma Delta Modulation; Structured Array; Switched Capacitor Circuits; Via-Configurable Array... phase of the input signal at the rate determined by the M output. Figure 9 shows the simulation results and Figure 10 shows the tiles used in the

  6. Stratigraphy and Evolution of Delta Channel Deposits, Jezero Crater, Mars

    Science.gov (United States)

    Goudge, T. A.; Mohrig, D.; Cardenas, B. T.; Hughes, C. M.; Fassett, C. I.

    2017-01-01

    The Jezero impact crater hosted an open-basin lake that was active during the valley network forming era on early Mars. This basin contains a well exposed delta deposit at the mouth of the western inlet valley. The fluvial stratigraphy of this deposit provides a record of the channels that built the delta over time. Here we describe observations of the stratigraphy of the channel deposits of the Jezero western delta to help reconstruct its evolution.

  7. Shoreface morphodynamics along the Danube Delta coast

    Science.gov (United States)

    Tatui, Florin; Vespremeanu-Stroe, Alfred

    2015-04-01

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

  8. Insulation coordination for delta connected transformers

    Energy Technology Data Exchange (ETDEWEB)

    Keri, A.J.F.; Musa, Y.I.; Halladay, J.A. (American Electric Power Service Corp., Columbus, OH (United States))

    1994-04-01

    It is common practice to install only phase to ground surge arresters for transformer insulation protection against electrical stresses. However, this may not adequately protect the delta connected transformer phase to phase winding insulation. High phase to phase overvoltages at the transformer terminals, due to capacitor switching, have been reported. This paper describes the excessive phase to phase overvoltages that can also occur due to wave propagation and surge transfer through transformers. This paper points out the need for surge arrester arrangements that protect both, phase to phase and phase to ground transformer insulations. Surge arrester arrangements, selection criteria, installation practices, and application considerations are discussed in this paper.

  9. Folding propensity of cyclohexylether-delta-peptides.

    Science.gov (United States)

    Arndt, Hans-Dieter; Ziemer, Burkhard; Koert, Ulrich

    2004-09-16

    [structure: see text] Linear (n = 2-18) and cyclic oligomers (n = 3-8) of a cyclohexylether-delta-amino acid (COA) were prepared in high yield and stereopurity. CD spectra of the linear oligomers were indicative of secondary structure formation. X-ray crystal structures of cyclic COA oligomers revealed hydrophobic packing and internal 5- and 10-membered-ring hydrogen bonds. Ether and amide oxygens reside preferably in an ap orientation. This conformational locking is apparently broken by a C-2 substituent in an asymmetric cyclotrimer, for which a zeolithe-like tubular structure was found.

  10. Morphodynamics of River Lowlands and Deltas: Combining Historical Maps with Satellite Data

    Science.gov (United States)

    Syvitski, J. P.; Hannon, M.; Kettner, A. J.; Jenkins, C. J.; Hutton, E. W.

    2007-12-01

    Cartographers have for centuries documented the courses of rivers and their delta's distributary channels. Yet these valuable historical maps have not often been placed into a Global Information System, and verified for their cartographic accuracy. We have obtained between 6 and 15 historical maps (17th - 20th century) for a set of global deltas (Indus, Ganges, Godavari, Krishna, Mahanadi, Brahmani, Yellow, Vistula Danube, Po, Rhone, Niger, Nile, Orinoco, Magdalena, Amazon, and Mississippi). The maps were examined for their registration accuracy, using the location of between 8 and 15 cities or towns. Those maps with RMS errors of less than 5 km had shape files established for the pathways of their rivers and distributary channels. Geolocated Space Shuttle Radar data were binned into 1 m topographic units (? 90 m horizontal footprint) for each river-delta system and used in combination with LANDSAT ETM+ (15-30 m horizontal footprint), as an underlay to each of the historical maps. The satellite data proved useful in verifying the historical courses of these channels, many of which are no longer active. Together the data provide valuable insight to the time dependent dynamics of distributary channel switching and migration, before the heavy anthropogenic footprint of the 20th century (river diversions through barrages, upstream damming of the sediment supply, mitigation of the seasonal flood wave, levee development and stabilization, human-affected delta subsidence, and agricultural infrastructure).

  11. Radar remote sensing for levee health assessment in the Sacramento-San Joaquin Delta

    Science.gov (United States)

    Sharma, P.; Jones, C. E.; Dudas, J.; Bawden, G. W.; Deverel, S. J.

    2014-12-01

    Levees and dikes form extensive flood protection infrastructure that often also serve critical water conveyance functions. We have studied the use of radar remote sensing for providing health assessment of levees, focusing on California's levee system. The Sacramento-San Joaquin Delta, which lies directly east of San Francisco Bay, is an area comprised of tidal marshland and reclaimed land in the form of ~60 islands surrounded by 1700 km of levees. Improved knowledge of subsidence across the region is needed to maintain the integrity of the Delta levee system, which protects the integrity and quality of the state's primary water supply. The western Delta is particularly critical because levee failure in this area would rapidly draw water of high salinity content into the channels conveying the fresh water supply. Here we report on a study that uses radar interferometry to measure the spatially and temporally varied levee movement and subsidence in the area, focusing particularly on Sherman Island, the westernmost island of the Delta. We use data from NASA's L-band (23.79 cm) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) collected at 6-week average interval from July 2009 through the current day. We show preliminary results for localized movement on and near the levees and for island-scale subsidence and discuss the techniques used for these measurements and how they could contribute to emergency response.

  12. A study of the climate change impacts on fluvial flood propagation in the Vietnamese Mekong Delta

    Directory of Open Access Journals (Sweden)

    P. D. T. Van

    2012-12-01

    Full Text Available The present paper investigated the extent of the flood propagation in the Vietnamese Mekong Delta under different projected flood hydrographs, considering the 2000 flood event (the 20-yr return period event, T. V. H. Le et al., 2007 as the basis for computation. The analysis herein was done to demonstrate the particular complexity of the flood dynamics, which was simulated by the 1-D modelling system ISIS used by the Mekong River Commission. The floods of the year 2050 are simulated using a projected sea level rise of +30 cm. The future flood hydrograph changes at Kratie, Cambodia, were also applied for the upstream boundary condition by using an adjusted regional climate model. Two future flood hydrographs were applied at the upstream part of the delta, the first one in a scenario of climate change without considering developments in the Mekong Basin,and the second one in a scenario of climate change taking into account future development of the delta. Analyses were done to identify the areas sensitive to floods, considering the uncertainty of the projection of both the upstream and downstream boundary conditions. In addition, due to the rice-dominated culture in the Vietnamese Mekong Delta, possible impacts of floods on the rice-based farming systems were also analysed.

  13. A study of the climate change impacts on fluvial flood propagation in the Vietnamese Mekong Delta

    Science.gov (United States)

    Van, P. D. T.; Popescu, I.; van Griensven, A.; Solomatine, D. P.; Trung, N. H.; Green, A.

    2012-12-01

    The present paper investigated the extent of the flood propagation in the Vietnamese Mekong Delta under different projected flood hydrographs, considering the 2000 flood event (the 20-yr return period event, T. V. H. Le et al., 2007) as the basis for computation. The analysis herein was done to demonstrate the particular complexity of the flood dynamics, which was simulated by the 1-D modelling system ISIS used by the Mekong River Commission. The floods of the year 2050 are simulated using a projected sea level rise of +30 cm. The future flood hydrograph changes at Kratie, Cambodia, were also applied for the upstream boundary condition by using an adjusted regional climate model. Two future flood hydrographs were applied at the upstream part of the delta, the first one in a scenario of climate change without considering developments in the Mekong Basin,and the second one in a scenario of climate change taking into account future development of the delta. Analyses were done to identify the areas sensitive to floods, considering the uncertainty of the projection of both the upstream and downstream boundary conditions. In addition, due to the rice-dominated culture in the Vietnamese Mekong Delta, possible impacts of floods on the rice-based farming systems were also analysed.

  14. Modeling multi-source flooding disaster and developing simulation framework in Delta

    Science.gov (United States)

    Liu, Y.; Cui, X.; Zhang, W.

    2016-12-01

    Most Delta regions of the world are densely populated and with advanced economies. However, due to impact of the multi-source flooding (upstream flood, rainstorm waterlogging, storm surge flood), the Delta regions is very vulnerable. The academic circles attach great importance to the multi-source flooding disaster in these areas. The Pearl River Delta urban agglomeration in south China is selected as the research area. Based on analysis of natural and environmental characteristics data of the Delta urban agglomeration(remote sensing data, land use data, topographic map, etc.), hydrological monitoring data, research of the uneven distribution and process of regional rainfall, the relationship between the underlying surface and the parameters of runoff, effect of flood storage pattern, we use an automatic or semi-automatic method for dividing spatial units to reflect the runoff characteristics in urban agglomeration, and develop an Multi-model Ensemble System in changing environment, including urban hydrologic model, parallel computational 1D&2D hydrodynamic model, storm surge forecast model and other professional models, the system will have the abilities like real-time setting a variety of boundary conditions, fast and real-time calculation, dynamic presentation of results, powerful statistical analysis function. The model could be optimized and improved by a variety of verification methods. This work was supported by the National Natural Science Foundation of China (41471427); Special Basic Research Key Fund for Central Public Scientific Research Institutes.

  15. Possible adaptation measures of agriculture sector in the Nile Delta to climate change impacts

    Directory of Open Access Journals (Sweden)

    S. M. Attaher

    2009-10-01

    Full Text Available The overall agricultural system in the Nile Delta region is considered as one of the highest intensive and complicated agriculture systems in the world. According to the recent studies, the Nile Delta region is one of the highly vulnerable regions in the world to climate change. Sea level rise, soil and water degradation, undiversified crop-pattern, yield reduction, pests and disease severity, and irrigation and drainage management were the main key factors that increased vulnerability of the agriculture sector in that region. The main objective of this study is to conduct a community-based multi-criteria adaptation assessment in the Nile Delta using a preset questionnaire. A list of possible adaptation measures for agriculture sector was evaluated. The results indicated that the Nile Delta growers have strong perceptions to act positively to reduce the impacts of climate change. They reflected the need to improve the their adaptive capacity based on clear scientific message with adequate governmental support to coop with the negative impacts of climate change.

  16. Tropical Storms Control the Pulse of Fluvial Sediment Supplied to the Mekong Delta

    Science.gov (United States)

    Darby, S. E.; Hackney, C. R.; Leyland, J.; Best, J.; Parsons, D. R.; Kummu, M.; Lauri, H.; Nicholas, A. P.; Aalto, R. E.

    2016-02-01

    The world's largest rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a significant fraction sequestered in the large deltas that are home to 14% of the world's population. Most (>70%) of these large deltas are under threat from a combination of rising sea levels and ground surface subsidence, while the rivers that feed them have also been subjected to damming, substantially reducing the sediment supply that is available for delta (re)construction. In this paper we focus on the Mekong River as an exemplar of a large, tropical, fluvial dispersal system. Wuse new measurements of the suspended sediment load, combined with hydrological modelling, to reconstruct inter-annual variations in sediment load with and without tropical cyclones during the period 1981-2005. We examine in particular the results at Kratie in Cambodia, a gauging station that is located within 250 km of the apex of the Mekong delta. Our results indicate that fluvial sediment loads at Kratie have undergone a large and rapid decline (at a rate of 2 Mt/yr, reducing the annual sediment load in this period by 50%) during the study period. This is a remarkable finding, but we also show that this decline in sediment load is attributable almost entirely to a commensurate decline in the proportion of the Mekong's sediment load that is forced by tropical storms. Our results have profound implications. The Mekong's great delta, the rice basket of SE Asia, is home to 17 million people. A sustainable supply of fluvial sediment is critical in preventing the Mekong's delta being `drowned' by rising sea levels. In recent years attention has been focused on the likely deleterious effects of hydropower dam construction in the Mekong Basin on the future sediment loads reaching the delta. However, it is evident that the delivery of sediment from the Mekong River has already undergone a substantial reduction, similar in magnitude to that associated with future dam-induced trapping, as a

  17. Geologic Subsidence in the Sacramento-San Joaquin Delta, California, and its Implications for Risk Assessment

    Science.gov (United States)

    Verosub, K. L.; Delusina, I.; Shlemon, R. J.

    2009-05-01

    California probably moves more water within its boundaries than any other political entity in the world. A key component of the state's water distribution system is the Sacramento-San Joaquin Delta. The decrease in land-surface elevation of artificial islands and tracts within the Delta is generally attributed to the draining of peat-rich wetlands and the subsequent disappearance of organic material through oxidation, wind erosion and other processes. This anthropogenic subsidence is of great concern because it increases pore pressure on the levees that surround the islands and tracts. Failure of Delta levees will have serious economic and social consequences not only locally, but for the entire state of California. However, the anthropogenic subsidence is superimposed on natural geologic subsidence that, for the most part, has received little attention in risk assessments. Ages for basal peat deposits in cores at 18 sites within the Delta indicate that peat formation began about 6500 years BP. At most sites the basal peat is about 9 meters below current sea level. Global sea level curves suggest that about 6500 years ago, sea level was only 3 meters below current sea level. Because peat is generally assumed to form at or slightly below sea level, the most reasonable interpretation of the data from the basal peat deposits is that about 6 meters of natural geologic subsidence has occurred in the Delta over the past 6500 years. A subsidence rate of about 1 meter per 1000 years agrees well with estimates deduced by Shlemon and Begg (1971) from the present depth of tilted, older alluvial fans in the Sacramento Valley. These observations have profound implications for the assessment and mitigation of risk in the Sacramento-San Joaquin Delta. First, the rate of geologic subsidence is comparable to the recent rate of sea level rise due to anthropogenic global climate change, and because these two effects operate in concert, stress increase on Delta levees may well be

  18. Continuous Water Quality Monitoring in the Sacramento-San Joaquin Delta to support Ecosystem Science

    Science.gov (United States)

    Downing, B. D.; Bergamaschi, B. A.; Pellerin, B. A.; Saraceno, J.; Sauer, M.; Kraus, T. E.; Burau, J. R.; Fujii, R.

    2013-12-01

    Characterizing habitat quality and nutrient availability to food webs is an essential step for understanding and predicting the success of pelagic organisms in the Sacramento-San Joaquin Delta (Delta). The difficulty is that water quality and nutrient supply changes continuously as tidal and wind-driven currents move new water parcels to and from comparatively static geomorphic settings. Understanding interactions between nutrient cycling, suspended sediment, and plankton dynamics with flow and tidal range relative to position in the estuary is critical to predicting and managing bottom up effects on aquatic habitat in the Delta. Historically, quantifying concentrations and loads in the Delta has relied on water quality data collected at monthly intervals. Current in situ optical sensors for nutrients, dissolved organic matter (DOM) and algal pigments (chlorophyll-A, phycocyanin) allow for real-time, high-frequency measurements on time scales of seconds, and extending up to years. Such data is essential for characterizing changes in water quality over short and long term temporal scales as well as over broader spatial scales. High frequency water quality data have been collected at key stations in the Delta since 2012. Sensors that continuously measure nitrate, DOM, algal pigments and turbidity have been co-located at pre-existing Delta flow monitoring stations. Data from the stations are telemetered to USGS data servers and are designed to run autonomously with a monthly service interval, where sensors are cleaned and checked against calibration standards. The autonomous system is verified against discrete samples taken monthly and intensively over periodic ebb to flood tidal cycles. Here we present examples of how coupled optical and acoustic data from the sensor network to improve our understanding of nutrient and DOM dynamics and fluxes. The data offer robust quantitative estimates of concentrations and constituent fluxes needed to investigate biogeochemical

  19. A global analysis of human habitation on river deltas

    Science.gov (United States)

    Edmonds, Douglas; Caldwell, Rebecca; Baumgardner, Sarah; Paola, Chris; Roy, Samapriya; Nelson, Amelia; Nienhuis, Jaap

    2017-04-01

    River deltas are ideal sites for human habitation because of their fertile floodplains, easy access to the ocean, and abundant land. But anthropogenic and natural processes are causing deltas to sink, which increases the probability of coastal flooding and human exposure to risk. The full extent of the risk posed to humans is unclear because the number of people living on river deltas is unknown. Towards this end we mapped the locations and areas of all deltas in the world (n= 1813). Using Google Earth we identified all river mouths (≥ 50 m wide) on marine coastlines that are also connected to an upstream catchment. Rivers that split into two or more active or relict distributary channels, end in a depositional protrusion from the shoreline, or do both, are defined as deltas. The depositional protrusion and distributary channel network define the geomorphic area of each delta. We mark the position of the delta apex at the first bifurcation, or for a single channel delta at the intersection of the regional shoreline and the main channel. We mark three lateral extents, one on either side of the main channel at the maximum displacement of the depositional protrusion or the distributary network, and one on the most basinward position of the delta. We define delta area as the convex hull around these extent points and the delta apex. For each delta area polygon we extract elevation from the Shuttle Radar Topography Mission dataset and population count in years 2000, 2005, 2010, 2015, and 2020 from Gridded Population of the World, version 4. In total, deltas cover 0.56% of the total area of the world yet contain 4.1% of the world's population. The population on deltas has grown from 237 million in 2000 to projected values of 322 million in 2020. Deltaic population is growing at 1.59% per year, which outpaces the world growth rate of 1.11%. Additionally, population density is increasing with time from 322 people per km2 in year 2000 to projected values of 422 people per

  20. Three-dimensional aerodynamic shape optimization of supersonic delta wings

    Science.gov (United States)

    Burgreen, Greg W.; Baysal, Oktay

    1994-01-01

    A recently developed three-dimensional aerodynamic shape optimization procedure AeSOP(sub 3D) is described. This procedure incorporates some of the most promising concepts from the area of computational aerodynamic analysis and design, specifically, discrete sensitivity analysis, a fully implicit 3D Computational Fluid Dynamics (CFD) methodology, and 3D Bezier-Bernstein surface parameterizations. The new procedure is demonstrated in the preliminary design of supersonic delta wings. Starting from a symmetric clipped delta wing geometry, a Mach 1.62 asymmetric delta wing and two Mach 1. 5 cranked delta wings were designed subject to various aerodynamic and geometric constraints.

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

    Directory of Open Access Journals (Sweden)

    Bethany R. Wilcox

    2015-03-01

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

  2. CMS: Aboveground Biomass for Mangrove Forest, Zambezi River Delta, Mozambique

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset provides several estimates of aboveground biomass from various regressions and allometries for mangrove forest in the Zambezi River Delta, Mozambique....

  3. Delta Plaza kohvik = The Delta Plaza Café / Margit Mutso

    Index Scriptorium Estoniae

    Mutso, Margit, 1966-

    2010-01-01

    Tallinnas Pärnu mnt. 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Hoone arhitektid Jüri Okas ja Marika Lõoke (AB J. Okas & M. Lõoke). Žürii liikme Mait Summataveti arvamus kohvikust

  4. Delta Alliance Young Professionals Award: Innovative solutions for delta challenges worldwide

    NARCIS (Netherlands)

    Krueger, I.; Miguel Ayala, L.; Driel, van W.F.

    2012-01-01

    Deltas are fragile, dynamic landforms at the boundary of land and ocean. They belong to the most valuable, but at the same time also to the most vulnerable areas in the world. With increasing pressure from population growth, industrialization and changing climate, it is more important than ever that

  5. Experimental delta formation in crater lakes and implications for interpretation of martian deltas

    NARCIS (Netherlands)

    Villiers, G. de; Kleinhans, M.G.; Postma, G.

    2013-01-01

    The morphology of delta deposits in crater lakes on Mars is indicative of upstream (e.g., flow discharge and sediment properties) and downstream (e.g., basin characteristics) parameters, from which the hydrological conditions at the time of formation can be inferred. To investigate the influences of

  6. Permafrost Mobilization from the Watershed to the Colville River Delta: Evidence from Biomarkers and 14C Ramped Pyrolysis

    Science.gov (United States)

    Zhang, X.; Bianchi, T. S.; Cui, X.; Rosenheim, B. E.; Ping, C. L.; Kanevskiy, M. Z.; Hanna, A. M.; Allison, M. A.

    2016-12-01

    As temperatures in the Arctic rise abnormally fast, permafrost in the region is vulnerable to extensive thawing. This could release previously frozen organic carbon (OC) into the contemporary carbon cycle, giving a positive feedback on global warming. Recent research has found the presence of particulate permafrost in rivers, deltas, and continental shelves in the Arctic, but little direct evidence exists on the mechanism of transportation of previously frozen soils from watershed to the coast. The Colville River in northern Alaska is the largest North American Arctic River with a continuous permafrost within its watershed. Previous work has found evidence for the deposition of previously frozen soils in the Colville River delta (Schreiner et al., 2014). Here, we compared the bulk organic carbon thermal properties, ages of soils and river and delta sediments from the Colville River drainage system using 14C Ramped Pyrolysis and chemical biomarkers. Our data show that deep permafrost soils as well as river and delta sediments had similar pyrograms and biomarker signatures, reflecting transport of soils from watershed to the delta. Surface soil had pyrograms indicative of less stable (more biodegradable) OC than deeper soil horizons. Similarity in pyrograms of deep soils and river sediment indicated the limited contribution of surface soils to riverine particulate OC inputs. Sediments in the delta showed inputs of yedoma (ice-rich syngenetic permafrost with large ice wedges) from the watershed sources (e.g., river bank erosion) in addition to peat inputs, that were largely from coastal erosion.

  7. Nanometer CMOS Sigma-Delta Modulators for Software Defined Radio

    CERN Document Server

    Morgado, Alonso; Rosa, José M

    2012-01-01

    This book presents innovative solutions for the implementation of Sigma-Delta Modulation (SDM) based Analog-to-Digital Conversion (ADC), required for the next generation of wireless hand-held terminals. These devices will be based on the so-called multistandard transceiver chipsets, integrated in nanometer CMOS technologies. One of the most challenging and critical parts in such transceivers is the analog-digital interface, because of the assorted signal bandwidths and dynamic ranges that can be required to handle the A/D conversion for several operation modes.   This book describes new adaptive and reconfigurable SDM ADC topologies, circuit strategies and synthesis methods, specially suited for multi-standard wireless telecom systems and future Software-defined-radios (SDRs) integrated in nanoscale CMOS. It is a practical book, going from basic concepts to the frontiers of SDM architectures and circuit implementations, which are explained in a didactical and systematic way. It gives a comprehensive overview...

  8. Low-voltage switched-current delta-sigma modulator

    Science.gov (United States)

    Tan, Nianxiong; Eriksson, Sven

    1995-05-01

    This paper presents the design of a fully differential switched-current delta-sigma modulator using a single 3.3-V power-supply voltage. At system level, we tailor the modulator structure considering the similarity and difference of switched-capacitor and switched-current realizations. At circuit level, we propose a new switched-current memory cell and integrator with improved common mode feedback, without which low power-supply-voltage operation would not be possible. The whole modulator was implemented in a 0.8- micron double-metal digital CMOS process. It occupies an active area of 0.53 x 0.48 mm(sup 2) and consumes a current of 0.6 mA from a single 3.3-V power supply. The measured dynamic range is over 10 b.

  9. Spectral factorization using the delta operator

    DEFF Research Database (Denmark)

    Rostgaard, Morten; Poulsen, Niels Kjølstad; Ravn, Ole

    1994-01-01

    In recent years many papers have been published abouth the gamma-operator, mostly caused by the better numerical properties and the rapprochement between continuous and discrete time. A major problem within the LQG-design of a delta-based input-output relation has been how to spectral-factorize i......In recent years many papers have been published abouth the gamma-operator, mostly caused by the better numerical properties and the rapprochement between continuous and discrete time. A major problem within the LQG-design of a delta-based input-output relation has been how to spectral......-factorize in an efficient way. The discrete-time method of Kuccera will not be applied since numerical word-length characteristics will be poor for fast sampling rates. In this paper a new approach is considered. A new gamma-operator (Tustin operator) is introduced, in order to make an iterative and numerical stable...... solution to the spectral factorization problem. The key idea is to use the gamma-operator resembled by its behavior to the differential operator....

  10. The Colorado river delta (Mexico: ecological importance and management = O delta do rio Colorado (Mexico: importância ecológica e gerenciamento

    Directory of Open Access Journals (Sweden)

    José Luis Fermán Almada

    2008-10-01

    Full Text Available The Colorado river delta is a unique coastal system in the world, as it combines two important systems: the Colorado river and the Gulf of California. Consequently, the delta is dominated by bilateral interests, and influenced by administrative, political and natural processes, which involve the countries of the United States and Mexico. Located in the northern part of the Gulf of California, under a condition of natural isolation, a series of environmental attributeshave been developed (biotic and abiotic that are only observed in is region. In this work, the development of the bilateral political relations and the most important ecological characteristicsare presented, as well as the management instruments that have been developed for over 80 years. From these issues, the possible scenario for the region is defined, and the development of methodologies for monitoring the effects of these possible tendencies on the natural components of the delta is proposed.O delta do rio Colorado é uma zona costeira única em todo o mundo, porassociar dois importantes sistemas: o próprio rio Colorado e o Golfo da Califórnia. Conseqüentemente, o delta é dominado por interesses bi-nacionais e influenciado por processos administrativos, políticos e naturais, envolvendo os Estados Unidos e o México. Localizado no norte do Golfo da Califórnia, sob uma condição de isolamento natural,desenvolveu-se uma série de atributos ambientais (bióticos e abióticos que só podem ser vistos nessa região. Neste trabalho, são apresentados o desenvolvimento das relações políticas bilaterais e as características ecológicas mais importantes, bem como osmecanismos de gerenciamento que vêm sido desenvolvidos por mais de 80 anos. A partir dessas questões, é definido um cenário tendencial possível para a região, e o desenvolvimento de metodologias para o acompanhamento dos efeitos dessas possíveis tendências sobre os componentes naturais do delta é proposto.

  11. Recent morphological changes of the Yellow River (Huanghe) submerged delta: Causes and environmental implications

    Science.gov (United States)

    Jiang, Chao; Pan, Shunqi; Chen, Shenliang

    2017-09-01

    .79 × 108 t/year and 1.29 × 108 t/year, respectively. The analysis from the latest hydrological data (2006-2015) suggests that over the decadal timescale, the evolution state of the YRSD currently has transitioned from constructive to destructive due to the weakened fluvial input. Moreover, there exists a close quantitative link between the progradation of the Yellow River subaerial delta (YRAD) and the YRSD over the five-year timescale, indicating that every 1 × 108 m3/year increase of the YRSD's yearly volumetric change will result in a 3.28 km2/year increase of the YRAD's yearly land-accretion area, and the YRAD will reach the extension/retreat balance state when yearly morphological change of the YRSD is at 0.73 × 108 m3/year.

  12. The Sacramento-San Joaquin Delta Conflict: Strategic Insights for California's Policymakers

    Science.gov (United States)

    Moazezi, M. R.

    2013-12-01

    The Sacramento-San Joaquin Delta - a major water supply source in California and a unique habitat for many native and invasive species--is on the verge of collapse due to a prolonged conflict over how to manage the Delta. There is an urgent need to expedite the resolution of this conflict because the continuation of the status quo would leave irreversible environmental consequences for the entire state. In this paper a systematic technique is proposed for providing strategic insights into the Sacramento-San Joaquin Delta conflict. Game theory framework is chosen to systematically analyze behavioral characteristics of decision makers as well as their options in the conflict with respect to their preferences using a formal mathematical language. The Graph Model for Conflict Resolution (GMCR), a recent game-theoretic technique, is applied to model and analyze the Delta conflict in order to better understand the options, preferences, and behavioral characteristics of the major decision makers. GMCR II as a decision support system tool based on GMCR concept is used to facilitate the analysis of the problem through a range of non-cooperative game theoretic stability definitions. Furthermore, coalition analysis is conducted to analyze the potential for forming partial coalitions among decision makers, and to investigate how forming a coalition can influence the conflict resolution process. This contribution shows that involvement of the State of California is necessary for developing an environmental-friendly resolution for the Delta conflict. It also indicates that this resolution is only achievable through improving the fragile levee systems and constructing a new water export facility.

  13. Delta: An object-oriented finite element code architecture for massively parallel computers

    Energy Technology Data Exchange (ETDEWEB)

    Weatherby, J.R.; Schutt, J.A.; Peery, J.S.; Hogan, R.E.

    1996-02-01

    Delta is an object-oriented code architecture based on the finite element method which enables simulation of a wide range of engineering mechanics problems in a parallel processing environment. Written in C{sup ++}, Delta is a natural framework for algorithm development and for research involving coupling of mechanics from different Engineering Science disciplines. To enhance flexibility and encourage code reuse, the architecture provides a clean separation of the major aspects of finite element programming. Spatial discretization, temporal discretization, and the solution of linear and nonlinear systems of equations are each implemented separately, independent from the governing field equations. Other attractive features of the Delta architecture include support for constitutive models with internal variables, reusable ``matrix-free`` equation solvers, and support for region-to-region variations in the governing equations and the active degrees of freedom. A demonstration code built from the Delta architecture has been used in two-dimensional and three-dimensional simulations involving dynamic and quasi-static solid mechanics, transient and steady heat transport, and flow in porous media.

  14. Improving Aquatic Plant Management in the California Sacramento-San Joaquin Delta

    Science.gov (United States)

    Bubenheim, David L.; Potter, Chris

    2018-01-01

    Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning and implementation of management practices for floating and submerged aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project, is working to enhance planning, decision-making and operational efficiency in the California Sacramento-San Joaquin Delta. Satellite and airborne remote sensing are used map (area coverage and biomass), direct operations, and assess management impacts on plant communities. Archived satellite records going are used to review results from previous climate and management events and aide in developing long-term strategies. Modeling at local and watershed scales provides insight into land-use effects on water quality. Plant growth models informed by remote sensing are being applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments, phenology, environmental regulations, and economics in selection of management practices. Initial utilization of remote sensing tools developed for mapping of aquatic invasive weeds improved operational efficiency by focusing limited chemical use to strategic areas with high plant-control impact and incorporating mechanical harvesting when chemical use is restricted. These assessment methods provide a comprehensive and quantitative view of aquatic invasive plants communities in the California Delta, both spatial and temporal, informed by ecological understanding with the objective of improving management and assessment effectiveness.

  15. A sigma-delta-based sparse synthetic aperture beamformer for real-time 3-D ultrasound.

    Science.gov (United States)

    Inerfield, M; Lockwood, G R; Garverick, S L

    2002-02-01

    Sigma-delta modulation allows delay resolution in ultrasound beamformers to be achieved by simple clock cycle delays applied to the undecimated bit-stream, greatly reducing the complexity of the signal processing and the number of bits in the datapath. The simplifications offered by this technique have the potential for low power and portable operation in advanced systems such as 3-D and color Doppler imagers. In this paper, an architecture for a portable, real-time, 3-D sparse synthetic aperture ultrasound beamformer based on sigma-delta modulation is presented, and its simulated performance is analyzed. Specifically, with a 65-element linear phased array and three transmit events, this architecture is shown to achieve a 1.1 degrees beamwidth, a -54-dB secondary lobe level, and a theoretical frame rate of 1700 frames/s at lambda/64 delay resolution using a second-order low pass sigma-delta modulator. Finally, a technique for modifying the proposed multi-beam architecture to allow improved analog-to-digital (A/D) resolution by premodulating the input signal for bandpass sigma-delta modulation is also presented.

  16. Biochemical and molecular characterization of delta-endotoxins in Bacillus thuringiensis.

    Science.gov (United States)

    Rosas-García, N M; Sánchez-Varela, A; Villegas-Mendoza, J M

    2009-11-01

    The delta-endotoxins (delta-ETX) of four native strains (RT7, RT19, RT25, and RT25), and one reference strain (4L1) of Bacillus thuringiensis were biochemically and molecularly characterized to determine their potential toxic activity against lepidopteran larvae. Crystals of delta-ETX were purified through a two-phase system to determine their morphology, molar mass, solubility, and resistance to proteinases. Toxic activity and cry gene content were also determined. Crystals from native strains exhibited polyhedral, irregular and cuboidal shapes, while those from 4L1 were bipyramidal. Seven proteins with estimated molar mass approximately 30-134 kDa were detected as the main components of the native delta-ETX. Only crystals from 4L1, RT24, and RT25 underwent complete solubilization at pH >12.0. Crystals from all strains produced trypsin-resistant peptides. None of the cry genes associated with toxicity in lepidopterans (cry1, cry2, cry9) was found in the native strains; however, 4L1 strain harbors cry1 and cry2 genes. Strains RT19 and RT25 caused significant mortality against Trichoplusia ni larvae with partial solubilization at pH 10, strain 4L1 caused 100 % mortality. Toxicity of native strains may come from a novel cry gene.

  17. Temporal changes of land use in Asi river delta (Hatay, Southern Turkey).

    Science.gov (United States)

    Korkmaz, Hüseyin; Cetin, Bayram; Kuscu, Veysel; Ege, Ismail; Bom, Ahmet; Ozsahin, Emre; Karatas, Atilla

    2012-04-01

    Increasing non-ecological land use necessitates more efficient using and utilization of land by man. Therefore, in recent years studies on sustainable land use have gained momentum. In this study, temporal change in land use, mainly between years 1940 and 2010, in Asi river delta on Southern Turkey was covered. To this end, in addition to literature, topographical maps and satellite images from year 1940 and after were used. Also, data were collected through field studies and interviews. Collected data were evaluated from geographical viewpoint using Geographical information system (GIS) and Remote sensing (RS) methods. Unplanned settlement in delta has reached levels high enough to threaten agricultural fields. Especially, greattendencyshown by Samandag city and the villages around it towards expanding into delta is an indicatorof this threat In additon, uncontrolled sand mining and touristic facilities on the coastline are also indicators of wrong land use. In future, direction of settlement to slopes around the delta rather than lowlands will be a much more ecological approach.

  18. The Mississippi Delta Cardiovascular Health Examination Survey: Study Design and Methods

    Science.gov (United States)

    Short, Vanessa L.; Ivory-Walls, Tameka; Smith, Larry; Loustalot, Fleetwood

    2015-01-01

    Assessment of cardiovascular disease (CVD) morbidity and mortality in subnational areas is limited. A model for regional CVD surveillance is needed, particularly among vulnerable populations underrepresented in current monitoring systems. The Mississippi Delta Cardiovascular Health Examination Survey (CHES) is a population-based, cross-sectional study on a representative sample of adults living in the 18-county Mississippi Delta region, a rural, impoverished area with high rates of poor health outcomes and marked health disparities. The primary objectives of Delta CHES are to (1) determine the prevalence and distribution of CVD and CVD risk factors using self-reported and directly measured health metrics and (2) to assess environmental perceptions and existing policies that support or deter healthy choices. An address-based sampling frame is used for household enumeration and participant recruitment and an in-home data collection model is used to collect survey data, anthropometric measures, and blood samples from participants. Data from all sources will be merged into one analytic dataset and sample weights developed to ensure data are representative of the Mississippi Delta region adult population. Information gathered will be used to assess the burden of CVD and guide the development, implementation, and evaluation of cardiovascular health promotion and risk factor control strategies. PMID:25844257

  19. The role of analytical chemistry in Niger Delta petroleum exploration: a review.

    Science.gov (United States)

    Akinlua, Akinsehinwa

    2012-06-12

    Petroleum and organic matter from which the petroleum is derived are composed of organic compounds with some trace elements. These compounds give an insight into the origin, thermal maturity and paleoenvironmental history of petroleum, which are essential elements in petroleum exploration. The main tool to acquire the geochemical data is analytical techniques. Due to progress in the development of new analytical techniques, many hitherto petroleum exploration problems have been resolved. Analytical chemistry has played a significant role in the development of petroleum resources of Niger Delta. Various analytical techniques that have aided the success of petroleum exploration in the Niger Delta are discussed. The analytical techniques that have helped to understand the petroleum system of the basin are also described. Recent and emerging analytical methodologies including green analytical methods as applicable to petroleum exploration particularly Niger Delta petroleum province are discussed in this paper. Analytical chemistry is an invaluable tool in finding the Niger Delta oils. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Oil, migration, and the political economy of HIV/AIDS prevention in Nigeria's Niger Delta.

    Science.gov (United States)

    Udoh, Isidore A

    2013-01-01

    In most of sub-Saharan Africa, HIV/AIDS is driven by endemic structural problems such as unemployment, poverty, forced migration, sexual exploitation, and concurrent sexual partnerships. In the Niger Delta of Nigeria, the epidemic is exacerbated by recurring regional conflict and negative environmental externalities resulting from 50 years of oil exploration. This article seeks to identify and analyze potential barriers to HIV/AIDS prevention and treatment from oil pollution and other environmental stressors in Nigeria's Niger Delta. We develop a conceptual framework to understand how oil politics and economic systems affect HIV risks in Nigeria. We then evaluate evidence of how environmental exposures can amplify risks. Using 10 semi-structured interviews, with 85 focus group participants, we test the argument that HIV transmission in the Niger Delta is related to a manipulative "divide and rule" power dynamic that characterizes multinational oil companies' role in shaping conflict contours in oil communities. Oil exploration destroys livelihoods, institutions, and values and forces impoverished and illiterate girls and women to migrate or be trafficked to urban centers as child laborers and sex workers. The elevated HIV/AIDS risk in the Niger Delta brings into focus the political economy of resource extraction, globalization, and indigenous, minority rights and struggles.

  1. Water Quality Management for Sustainable Aquaculture Production in Mekong delta: A Case Study in Thot Not District, Can Tho Province of Vietnam

    OpenAIRE

    Nguyen Thi Hai Ninh; NGUYEN Mau, Dung; HO Ngoc, Cuong

    2016-01-01

    Production intensification of semi-intensive and intensive culture system has become a trend in the Mekong delta. However, the practice of these systems by small farm households usually results in water pollution, then placing negative consequences on aquaculture yield and quality. Water quality management is therefore nowadays one of the most important in aquaculture production in the Delta. The purpose of this paper is to investigate the water quality management of aquaculture farm househol...

  2. Complex rearrangements within the human J delta-C delta/J alpha-C alpha locus and aberrant recombination between J alpha segments

    NARCIS (Netherlands)

    Baer, R.; Boehm, T.; Yssel, H.; Spits, H.; Rabbitts, T. H.

    1988-01-01

    We have examined DNA rearrangements within a 120 kb cloned region of the human T cell receptor J delta-C delta/J alpha-C alpha locus. Three types of pattern emerge from an analysis of T cell lines and clones. Firstly, cells with two rearrangements within J delta-C delta; secondly, cells with one

  3. Homosexuality amongst migrant oil workers in the Niger Delta ...

    African Journals Online (AJOL)

    Aims: To determine the prevalence of homosexuality among migrant oil workers in Niger Delta. Methods: A prospective questionnaire – based study was conducted among migrant oil workers in the Niger Delta region of Nigeria. The design was to determine the prevalence of homosexuality in the workers in oil workers.

  4. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

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

    2012-01-01

    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by

  5. Occurrence of elevated nitrate in groundwaters of Krishna delta, India

    African Journals Online (AJOL)

    Nitrate concentrations were measured in the groundwater samples of Krishna delta, India. The results indicate a large variation of nitrate from 10 - 135 mg/l. In 79 groundwater samples, about 39% shows high nitrate contents (>50 mg/l), which is more than the permissible limits in drinking water. In north Krishna delta 49% ...

  6. Pattern of Complicated Unsafe Abortions in Niger Delta University ...

    African Journals Online (AJOL)

    Alasia Datonye

    developing world. This study aims to determine the pattern of complicated unsafe abortions in Niger delta. University Teaching Hospital (NDUTH) Okolobiri. Methods: The study is a four-year retrospective analysis of cases of complicated unsafe abortion managed at the. Niger Delta University Teaching Hospital Okolobiri,.

  7. The Niger Delta : A Stakeholder Approach to Environmental Development

    OpenAIRE

    Linden, O.; Moffat, D.; Singh, J.

    1995-01-01

    The Niger Delta is one of the world's largest wetlands and includes by far the largest mangrove forest in Africa. Within this extremely valuable ecosystem, oil activities are widespread - Rivers State and Delta State produce 75 percent of Nigeria's petroleum, which represents over 50 percent of national government revenues. However, despite its vast oil reserves, the region remains poor. G...

  8. Occurrence of elevated nitrate in groundwaters of Krishna delta, India

    African Journals Online (AJOL)

    Administrator

    Krishna delta 49% and in south Krishna delta 26% water samples were found to exceed the permissible limits. This study indicates that ... plain aquifers are the main source of water for agriculture and domestic purposes. The deltaic ..... can result in runoff and leaching of residual nitrate in the soil and in turn pollute the ...

  9. Delta's paradise: a challenge for lan[d]scape architects

    NARCIS (Netherlands)

    Boekhorst, te J.K.M.; Toorn, van den M.W.M.

    1996-01-01

    Paradise as a metaphor has always played an important role in art. This is definitely true for the art of garden design, but paradise is also a metaphor that can be used for the landscape. Some of the most interesting landscapes are found in deltas. Deltas are rich in natural and economic potential.

  10. Caribbean piracy and youth restiveness in Niger delta: A ...

    African Journals Online (AJOL)

    Our aim in this paper is to make a comparative analysis of Caribbean piracy and youth restiveness in Niger Delta of Nigeria. It will not be out of place to carry out such an analysis having seen, heard or read of the ongoing chaos, insecurity in the. Niger Delta Zone in Nigeria. We have to look at the past to find out such similar

  11. Gamma/delta T lymphocytes in Mycobacterium tuberculosis infection.

    Science.gov (United States)

    Balikó, Z; Szereday, L; Szekeres-Bartho, J

    1997-04-01

    Data on the percentage of gamma/delta T lymphocytes in the peripheral blood of patients infected with Mycobacterium tuberculosis are few and contradictory. The percentage of gamma/delta T lymphocytes in the peripheral blood of tuberculin positive and tuberculin negative patients with Mycobacterium tuberculosis infection and healthy controls was compared. Thirty six patients infected with Mycobacterium tuberculosis and 11 healthy controls were studied. Lymphocytes were separated, cytocentrifuged onto glass microscope slides, and reacted with anti-gamma/delta monoclonal antibody. The percentage of gamma/delta positive cells was determined by microscopic counting of 300 lymphocytes. No difference was found in the percentage of gamma/delta T lymphocytes between patients and controls. However, when the patients were divided into two groups according to reactivity or non-reactivity in the Mantoux skin reaction a higher percentage of gamma/delta T lymphocytes was found in the peripheral blood of patients with tuberculin anergy than in tuberculin positive patients or controls. Higher gamma/delta T cell counts are found in tuberculin negative patients with tuberculosis than in tuberculin positive patients or tuberculin positive controls. The high gamma/delta T cell counts in tuberculin anergic patients may reflect a shift in the immune response in a Th2 direction characterised by increased antibody production and decreased cell mediated responses.

  12. Information Needs of Cassava Farmers in Delta State of Nigeria

    African Journals Online (AJOL)

    are currently three cassava projects implemented. Information Needs of Cassava Farmers in Delta ... study assessed the information needs of cassava farmers in Oshimili North Local Government Area of Delta. State. Specifically, the study ... An International Journal of Basic and Applied Research through the IITA in Nigeria.

  13. A Delta-Sigma beamformer with integrated apodization

    DEFF Research Database (Denmark)

    Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Hemmsen, Martin Christian

    2013-01-01

    This paper presents a new design of a discrete time Delta-Sigma (ΔΣ) oversampled ultrasound beamformer which integrates individual channel apodization by means of variable feedback voltage in the Delta-Sigma analog to digital (A/D) converters. The output bit-width of each oversampled A/D converte...

  14. West Indian Ocean Deltas Exchange and Research Network | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    The West Indian Ocean Deltas Exchange and Research Network (WIoDER) aims to support research, training, and pilot interventions in up to four Western Indian Ocean river deltas under pressure from human activity. Research will examine in particular the links between population mobility, agriculture, climate change, ...

  15. Indanylacetic acids as PPAR-delta activator insulin sensitizers.

    Science.gov (United States)

    Wickens, Philip; Zhang, Chengzhi; Ma, Xin; Zhao, Qian; Amatruda, John; Bullock, William; Burns, Michael; Cantin, Louis-David; Chuang, Chih-Yuan; Claus, Thomas; Dai, Miao; Dela Cruz, Fernando; Dickson, David; Ehrgott, Frederick J; Fan, Dongping; Heald, Sarah; Hentemann, Martin; Iwuagwu, Christiana I; Johnson, Jeffrey S; Kumarasinghe, Ellalahewage; Ladner, David; Lavoie, Rico; Liang, Sidney; Livingston, James N; Lowe, Derek; Magnuson, Steve; Mannelly, Gretchen; Mugge, Ingo; Ogutu, Herbert; Pleasic-Williams, Susan; Schoenleber, Robert W; Shapiro, Jeff; Shelekhin, Tatiana; Sweet, Laurel; Town, Christopher; Tsutsumi, Manami

    2007-08-01

    A series of indane acetic acid derivatives were prepared which show a spectrum of activity as insulin sensitizers and PPAR-alpha and PPAR-delta ligands. In vivo data are presented for insulin sensitizers with selectivity for PPAR-delta over PPAR-alpha.

  16. The Niger Delta Avengers, Autonomous Ethnic Clans and Common ...

    African Journals Online (AJOL)

    These common consumption goods have eluded ordinary Nigerians with more devastating effect in the Niger Delta region owing to ineptitude of state actors and their accomplices in Multinational Oil Corporations. This paper therefore investigated the sudden emergence of Niger Delta Avengers militant group. It also raised ...

  17. Design of the workplace for a Delta Robot

    OpenAIRE

    Romeo Alba, Xavier

    2010-01-01

    This project presents an introduction to parallel kinematic robots focused on Delta robot from the point of view of applications, kinematics, mechanics and investigation. The second part of the document shows the implantation of the fastest Delta robot (FANUC M-1iA 0.5A) at University of Zilina.

  18. An annotated list of Fishes from the Niger Delta

    NARCIS (Netherlands)

    Boeseman, M.

    1963-01-01

    At the end of November 1960, the Leiden Museum received an interesting collection of animals, mostly fishes, from the Niger delta. All specimens were collected by Mr. H. J. G. Beets, at the time employed by Shell B.P. — Delta Investigations, during the period May to August 1960, and in the region

  19. The Localizing Value Of Focal Delta Slowing In Temporal Lobe ...

    African Journals Online (AJOL)

    Background Clinical and structural correlates of lateralized interictal delta activity in patients with temporal lobe epilepsy (TLE) have been well documented in the literature. Nevertheless, its occurrence has not been considered a significant clinical feature. Objective To evaluate the significance of focal delta- range slowing ...

  20. Planting Bottomland Hardwoods for Wildlife in the Delta

    Science.gov (United States)

    Emile S. Gardiner; John A. Stanturf

    2000-01-01

    Tree season soon will be upon us. No, not cottontrees! The best time for planting dormant hardwood seedlings in the Delta is from December through February. All trees native to the Delta have some value as wildlife habitat. While some tree species produce mast, foliage, nectar, or fiber that are eaten by animals, others provide cover, vertical structure for nesting...