The microfauna assemblages as indicators of paleoenvironmental changes in the Miocene fluvial- lacustrine cycles (NE Duero Basin, Spain

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A. Herrero-Hernández

2016-11-01

Full Text Available The siliclastic and carbonate deposits are interbedded in the Villadiego area (Miocene, NE Duero Basin. They have been subdivided into two high-rank depositional sequences: DDS and CDS. The sedimentary analysis of these units and the study of the microfauna content, mainly ostracods, led to the identification of lacustrine-fluvial interaction systems. The sedimentary characteristics reveal the existence of fluvial systems of gravel, flood plains and lacustrine systems that were interconnected and intimately related in north-south direction. In the sedimentological analysis, thirteen types of fluvial and lacustrine lithofacies and six genetic facies associations were recognized. The top of DDS is the result of lake level risings. The CDS shows a deepening-shallowing cycle. The ostracod micropaleontological analysis of the sediments have been studied, with the aim of reconstructing the palaeoenvironmental evolution of this area. These microfauna assemblages integrated with the analysis of the sedimentary facies allowed to conclude the existence of lakes with a water-bearing level of few tens of meters. A change in the chemical conditions of the waters, which evolved from oligohaline and carbonated to mesohaline and sulphated is concluded.

Index to Marine and Lacustrine Geological Samples (IMLGS)

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National Oceanic and Atmospheric Administration, Department of Commerce — The Index to Marine and Lacustrine Geological Samples (IMLGS) describes and provides access to ocean floor and lakebed rock and sediment samples curated by...

In-situ monitoring of deformation of clayey and volcanic sequences in the lacustrine plain of Iztapalapa, Mexico City

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Carreon-Freyre, D.; Cerca, M.; Barrientos, B.; Gutierrez, R.; Blancas, D.

2012-12-01

Major cities of Central Mexico with lowering of land elevation problems are located in inter-volcanic and fault bounded basins within the central Trans-Mexican Volcanic Belt (TMVB). The most representative and studied case of ground deformation is Mexico City, where the Iztapalapa Municipality presents the highest population density. This area is located over the geological contact between the "Sierra de Santa Catarina" volcanic range and a lacustrine plain. Filling of lacustrine basins includes silty and clayey sediments as well as pyroclastic deposits (coarse and fine grained) and volcanic rocks layers. We used Ground Penetrating Radar (GPR) and MASW prospection to evaluate contrasts in the physical properties of fine grained soils and identify geometry of the deformational features and implemented a mechanical system for in situ monitoring in fractured sites. Deformational features in this basin reflect an interplay between the geological history (depositional conditions), load history, seismic activity, and faulting. Plastic mechanical behaviour predominates in these clayey sediments and differential deformation locally triggers brittle fracturing and/or subsidence of the surface. In this work we present the results of monitoring and characterization of ground deformation and fracturing in different sequences, our results show a dynamic interplay between the mechanisms of ground fracturing and the stress history of sedimentary sequences. Relating the mechanical behaviour of the studied sequences with variations of physical and geological properties should be taken into account to estimate land level lowering and risk of fracturing for urban development planning.

A Middle-Upper Miocene fluvial-lacustrine rift sequence in the Song Ba Rift, Vietnam

DEFF Research Database (Denmark)

Lars H., Nielsen; Henrik I., Petersen; Nguyen D., Dau

2007-01-01

The small Neogene Krong Pa graben is situated within the continental Song Ba Rift, which is bounded by strike-slip faults that were reactivated as extensional faults in Middle Miocene time. The 500 m thick graben-fill shows an overall depositional development reflecting the structural evolution...... subsidence rate and possibly a higher influx of water from the axial river systems the general water level in the graben rose and deep lakes formed. High organic preservation in the lakes prompted the formation of two excellent oil-prone lacustrine source-rock units. In the late phase of the graben...... as carrier beds, whereas the braided fluvial sandstones and conglomerates along the graben margins may form reservoirs. The Krong Pa graben thus contains oil-prone lacustrine source rocks, effective conduits for generated hydrocarbons and reservoir sandstones side-sealed by the graben faults toward...

Deformation of ``Villafranchian'' lacustrine sediments in the Chisone Valley (Western Alps, Italy)

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Collo, Giovanni; Giardino, Marco

1997-09-01

The Chisone Valley is located in the internal NW Alps, in the Pinerolese District, an area characterized by present low to medium seismicity. Fine-grained sediments (sand, silt and clay with interbedded gravel) crop out in the lower Chisone Valley: they were first interpreted as glaciolacustrine deposits, and then as a lacustrine infilling of the valley floor probably due to differential uplifting of the valley mouth. Review of this data, together with new field and palynological observations, lead us to refer the lacustrine deposits to approximately the Lower Pleistocene (Villafranchian). In many outcrops, the lacustrine deposits show strong soft-sediment deformation such as convolute laminations, water-escape structures and disrupted beds, some of them associated with folds and faults (cm to dm in size); only two sites show metric to decametric folds and faults trending E-W and N-S. Detailed structural analysis conducted along a recently exposed section (Rio Gran Dubbione site) shows several soft-sediment deformation features on the limbs of mesoscale folds. Because of their intimate structural association, the origin of these minor structures seems to be connected to synsedimentary activity on reverse and normal faults (m to dm in size) affecting the lacustrine deposits in the same locality. Soft-sediment deformation features can be interpreted as possible paleoseismites. If so, the present seismicity of the Pinerolese District, which is the major area of such activity in NW Italy, cannot be considered an isolated episode in the geological evolution of the region; even if there is no supporting evidence for continuous seismicity, the deformations in the lacustrine sediments of the Chisone Valley testify to Early Pleistocene seismic activity, probably related to the recent tectonic evolution of the internal side of the NW Alps.

Devonian lacustrine shore zone architecture imaged with ground penetrating radar

DEFF Research Database (Denmark)

Andrews, Steven D.; Moreau, Julien; Archer, Stuart

. The shore zone sandstones overlie playa facies which contain abundant desiccation horizons, reflecting the most arid phase in the climatically controlled lacustrine cycle. As climatic conditions ameliorated the rejuvenation of fluvial systems resulted in the transport of sand out into the basin. Initial...... deposition was limited to intermittent events where sediment was laid down on a water saturated substrate. Some of these may have occurr­­­ed subaqueously as small scale turbidity flows. High resolution fluctuations in lake level resulted in periodic short lived reworking events along the lake margin which...

Archive of Geosample Data and Information from the University of Minnesota National Lacustrine Core Repository (LacCore)

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National Oceanic and Atmospheric Administration, Department of Commerce — The National Lacustrine Core Repository (LacCore), operated by the University of Minnesota is a partner in the Index to Marine and Lacustrine Geological Samples...

Development and Rainfed Paddy Soils Potency Derived From Lacustrine Material in Paguyaman, Gorontalo

OpenAIRE

Nurdin

2011-01-01

Rainfed paddy soils that are derived from lacustrine and include of E4 agroclimatic zone have many unique properties and potentially for paddy and corn plantations. This sreseach was aimed to: (1) study the soil development of rainfed paddy soils derived from lacustrine and (2) evaluate rainfed paddy soils potency for paddy and corn in Paguyaman. Soil samples were taken from three profiles according to toposequent, and they were analyzed in laboratory. Data were analyzed with descripti...

Ecological state of the Romanian Black Sea littoral lacustrine ecosystems

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Gomoiu, M.-T.

2009-04-01

The author uses the results of his own researches as well as data from specialty literature to assess the ecological state of some typical lacustrine ecosystems considered, about 50 years ago, of major importance by their functions, services and researches, for the human populations in the settlements nearby. Based on this assessment the author recommends a few criteria which can be taken into account when programs of integrated management of these coastal ecosystems are initiated. The paper focuses on the study cases regarding the following major ecosystems: 1. Razelm-Sinoie Lagoon Complex - tightly linked to the Danube River and Delta systems, 2. Taşaul Lake - interfered in the last two decades by a branch of the DanubeRiver - Black Sea Canal and 3. Techirghiol Lake - for a long time under the sea level, a hyperhaline lake with therapeutic, sapropelic mud, disturbed by huge quantities of freshwaters infiltrated from the irrigation system. At present, the state of the lacustrine ecosystems at the Romanian Black Sea Coast can be characterized, mainly, by the following aspects: · Increase in the quantities of nutrients and chemical toxicants; · Rise in the level and frequency of eutrophication and pollution phenomena; · Drastic reduction of specific diversity; · Simplification of communities' structure - biocoenosis homogeneity; · Decrease in numerical abundance and biomass of benthic populations and consequently, low biofilter power by the decrease of the filter-feeder populations; · Worsening of the qualitative and the quantitative state of the biological benthic resources; · Thriving opportunistic forms (e.g. the worms causing sediment bioturbation); · Invasion by some exotic species, with harmful, unexpected consequences; · All populations undergo quantitative fluctuations; · Decrease in the fish population and in the use values of lacustrine assets, with strong impact on the welfare of the human society. Almost all pressure forms associated with the

Geochemical characteristics of Tertiary saline lacustrine oils in the Western Qaidam Basin, northwest China

International Nuclear Information System (INIS)

Zhu Yangming; Weng Huanxin; Su Aiguo; Liang Digang; Peng Dehua

2005-01-01

Based on the systematic analyses of light hydrocarbon, saturate, aromatic fractions and C isotopes of over 40 oil samples along with related Tertiary source rocks collected from the western Qaidam basin, the geochemical characteristics of the Tertiary saline lacustrine oils in this region was investigated. The oils are characterized by bimodal n-alkane distributions with odd-to-even (C 11 -C 17 ) and even-to-odd (C 18 -C 28 ) predominance, low Pr/Ph (mostly lower than 0.6), high concentration of gammacerane, C 35 hopane and methylated MTTCs, reflecting the high salinity and anoxic setting typical of a saline lacustrine depositional environment. Mango's K 1 values in the saline oils are highly variable (0.99-1.63), and could be associated with the facies-dependent parameters such as Pr/Ph and gammacerane indexes. Compared with other Tertiary oils, the studied Tertiary saline oils are marked by enhanced C 28 sterane abundance (30% or more of C 27 -C 29 homologues), possibly derived from halophilic algae. It is noted that the geochemical parameters of the oils in various oilfields exhibit regular spatial changes, which are consistent with the depositional phase variations of the source rocks. The oils have uncommon heavy C isotopic ratios (-24%o to -26%o) and a flat shape of the individual n-alkane isotope profile, and show isotopic characteristics similar to marine organic matter. The appearance of oleanane and high 24/(24 + 27)-norcholestane ratios (0.57-0.87) in the saline oils and source rocks confirm a Tertiary organic source

Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

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Dubiel, R.F. (Geological Survey, Denver, CO (USA))

1989-09-01

Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

Petrophysical characterization of the lacustrine sediment succession drilled in Lake El'gygytgyn, Far East Russian Arctic

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A. C. Gebhardt

2013-08-01

Full Text Available Seismic profiles of Far East Russian Lake El'gygytgyn, formed by a meteorite impact some 3.6 million years ago, show a stratified sediment succession that can be separated into subunits Ia and Ib at approximately 167 m below lake floor (=~3.17 Ma. The upper (Ia is well-stratified, while the lower is acoustically more massive and discontinuous. The sediments are intercalated with frequent mass movement deposits mainly in the proximal areas, while the distal region is almost free of such deposits at least in the upper part. In spring 2009, a long core drilled in the lake center within the framework of the International Continental Scientific Drilling Program (ICDP penetrated the entire lacustrine sediment succession down to ~320 m below lake floor and about 200 m farther into the meteorite-impact-related bedrock. Downhole logging data down to 390 m below lake floor show that the bedrock and the lacustrine part differ significantly in their petrophysical characteristics. The contact between the bedrock and the lacustrine sediments is not abrupt, but rather transitional with a variable mixture of impact-altered bedrock clasts in a lacustrine matrix. Physical and chemical proxies measured on the cores can be used to divide the lacustrine part into five different statistical clusters. These can be plotted in a redox-condition vs. input-type diagram, with total organic carbon content and magnetic susceptibility values indicating anoxic or oxic conditions and with the Si / Ti ratio representing more clastic or more biogenic input. Plotting the clusters in this diagram allows identifying clusters that represent glacial phases (cluster I, super interglacials (cluster II, and interglacial phases (clusters III and IV.

Palaeoenvironmental assessment of Westphalian fluvio-lacustrine deposits of Lorraine (France) using a combination of organic geochemistry and sedimentology

International Nuclear Information System (INIS)

Fleck, Stephanie; Michels, Raymond; Izart, Alain; Elie, Marcel; Landais, Patrick

2001-01-01

The quality and the quantity of organic carbon preserved in modern and ancient terrestrial sediments is the result of a complex interactions of sedimentological factors, such as in-situ productivity, allochtonous supply of organic matter, oxidation processes, biodegradation and sediment accumulation rates. The study aims at utilizing multidisciplinary information in order to characterize the palaeoenvironment in Westphalian fluvio-lacustrine deposits of the Lorraine Coal Basin (NE France). In this basin, the lack of outcrops is the major difficulty. To compensate for this problem, sedimentology, and molecular geochemistry are combined in order to significantly improve the palaeoenvironmental assessment of the area. Geochemical analyses and sedimentology have been carried out on several core samples of the Saulcy drill hole to evaluate local palaeoenvironmental variability. The lithofacies associations in the Upper Carboniferous of the Lorraine basin suggest an alluvial plain environment without marine incursions. Sedimentological interpretations of the core, as well as comparison with sedimentological models, suggests the recognition of different depositional environments from braided and/or meandering rivers to swamp and lakes. The organic geochemistry is focussed on the recognition of aliphatic hydrocarbons and especially on molecular biomarkers, which provide valuable information about the original organic matter and the transformations that took place during sedimentation and diagenesis. In the Lorraine basin, the botanical variability is high and clearly related to the position of the vegetation communities in the fluvial system. The biomarkers (e.g., diterpanes, steranes) show variations, which can be related to the diversity of this ecosystem. In this study, a reinterpretation of the environmental zonation in the sterane ternary diagram adapted to a fluvio-lacustrine sedimentology is proposed. The correlation between sedimentological and geochemical

Lacustrine Environment Reservoir Properties on Sandstone Minerals and Hydrocarbon Content: A Case Study on Doba Basin, Southern Chad

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Sumery, N. F. Mohd; Lo, S. Z.; Salim, A. M. A.

2017-10-01

The contribution of lacustrine environment as the hydrocarbon reservoir has been widely known. However, despite its growing importance, the lacustrine petroleum geology has received far less attention than marine due to its sedimentological complexity. This study therefore aims in developing an understanding of the unique aspects of lacustrine reservoirs which eventually impacts the future exploration decisions. Hydrocarbon production in Doba Basin, particularly the northern boundary, for instance, has not yet succeeded due to the unawareness of its depositional environment. The drilling results show that the problems were due to the: radioactive sand and waxy oil/formation damage, which all are related to the lacustrine depositional environment. Detailed study of geological and petrophysical integration on wireline logs and petrographic thin sections analysis of this environment helps in distinguishing reservoir and non-reservoir areas and determining the possible mechanism causing the failed DST results. The interpretations show that the correlation of all types> of logs and rho matrix analysis are capable in identifying sand and shale bed despite of the radioactive sand present. The failure of DST results were due to the presence of arkose in sand and waxy oil in reservoir bed. This had been confirmed by the petrographic thin section analysis where the arkose has mineral twinning effect indicate feldspar and waxy oil showing bright colour under fluorescent light. Understanding these special lacustrine environment characteristics and features will lead to a better interpretation of hydrocarbon prospectivity for future exploration.

Highly calcareous lacustrine soils in the Great Konya Basin, Turkey

NARCIS (Netherlands)

Meester, de T.

1971-01-01

The Great Konya Basin is in the south of the Central Anatolian Plateau in Turkey. It is a depression without outlet to the sea. The central part of the Basin is the floor of a former Pleistocene lake, the Ancient Konya Lake. This area, called the Lacustrine
Plain, has highly calcareous

Investigation of the radioactive and heavy metal pollution of the danube Delta lacustrine sediments and soil

International Nuclear Information System (INIS)

Dinescu, L.C.; Ciortea, C.; Fluerasu, D.; Stoica, P.; Duliu, O.G.; Stoica, P.

2005-01-01

Results obtained for five lacustrine sediment cores and three soil samples, collected in 1996 from Danube Delta, by using INAA, ICP-MS, and TTPIXE analytical methods, are presented. The measured vertical profiles identified as possible pollutants the following elements: Al, Cu, Zn, As, Ag, Cd, In, Sn, Sb, Hg, Tl, Pb, and Bi. In the sediment cores, the determined elements, except V and Ni, show near-surface enrichment relative to the lower part (1.3-3 enrichment factor, except 5 - 7 for Cd and Hg). In some few cases, As, Cd, Cu, Cr, Mn, and Pb exceeded the minimum threshold of safety defined by the Romanian legislation. For soil samples, increased (1.5-3 times) values at surface in comparison with the 30 cm depth was also found, but values much lower compared to lacustrine sediments, indicating the riverine transport as the main source of heavy-metal near-surface contamination of the lacustrine sediments

AMS radiocarbon dating of lacustrine sediment from an impact crater in northeastern China

Energy Technology Data Exchange (ETDEWEB)

Liu, K.X. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Chen, M., E-mail: mchen@gig.ac.cn [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Ding, X.F.; Fu, D.P. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Ding, P. [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Shen, C.D., E-mail: cdshen@gig.ac.cn [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Xiao, W.S. [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China)

2013-01-15

In order to investigate the origin and age of a bowl-shaped crater with 1.8 km diameter in northeastern China, a core drilling about 110 m in total was carried out in 2009 at the center of the crater. A 106-m-thick unit of lacustrine sediment is revealed under a surface layer of about 1 m of yellow soil. The impact origin has been confirmed based on geological analysis. In this paper, we report the AMS {sup 14}C dating results of lacustrine sediment. The data suggest that the meteorite impact in Xiuyan happened more than 50,000 years ago and a two-section linear relationship of {sup 14}C ages with the depth shows a stable sediment environment through the two time stages.

Lacustrine-humate model for primary uranium ore deposits, Grants Uranium Region, New Mexico

International Nuclear Information System (INIS)

Turner-Peterson, C.E.

1985-01-01

Two generations of uranium ore, primary and redistributed, occur in fluvial sandstones of the Upper Jurassic Morrison Formation in the San Juan basin; the two stages of ore formation can be related to the hydrologic history of the basin. Primary ore formed soon after Morrison deposition, in the Late Jurassic to Early Cretaceous, and a model, the lacustrine-humate model, is offered that views primary mineralization as a diagenetic event related to early pore fluid evolution. The basic premise is that the humate, a pore-filling organic material closely associated with primary ore, originated as humic acids dissolved in pore waters of greenish-gray lacustrine mudstones deposited in the mud-flat facies of the Brushy Basin Member and similar K shale beds in the Westwater Canyon Member. During compaction associated with early burial, formation water expelled from lacustrine mudstone units carried these humic acids into adjacent sandstone beds where the organics precipitated, forming the humate deposits that concentrated uranium. During the Tertiary, much later in the hydrologic history of the basin, when Jurassic sediments were largely compacted, oxygenated ground water flowed basinward from uplifted basin margins. This invasion of Morrison sandstone beds by oxidizing ground waters redistributed uranium from primary ores along redox boundaries, forming ore deposits that resemble roll-front-type uranium ores. 11 figures

14 C dating and isotopic composition of lacustrine sediment in the Vale do Ribeira, south-western Sao Paulo State

International Nuclear Information System (INIS)

Saia, Soraya E.M.G.; Pessenda, Luiz C.R.; Gouveia, Susy E.M.; Vidotto, Elaine; Ledru, Marie-Pierre; Karmann, Ivo; Amaral, Paula G.; Bendassoli, Jose A.

2005-01-01

This work is part of a multi and interdisciplinary study involving paleoenvironmental records based on systematic and joint actions of pollen, isotopic composition ( 12 C, 13 C and 14 N, 15 N) and 14 C dating of lacustrine sediment. Samplings have been made in the Lagoa Grande located at Parque Estadual de Turismo do Alto Ribeira - PETAR, in the Vale do Ribeira, south-western Sao Paulo state. This integration must improve significantly the studies of vegetation and climate changes that occurred during the Late Pleistocene in the southeastern region of Brazil. The δ 13 C results of lacustrine sediment presented values from -23 to -30 per mille with isotopic tendencies of enrichment-depletion in the whole profile. The highest values of total organic carbon (TOC) and C/N associated with depleted δ 13 C values, were linked to organic matter from C 3 land plant and interpreted as the presence of denser arboreal vegetation around the lake. The smallest values of TOC and C/N associated with enriched δ 13 C values were linked to phytoplanktonic influence and/or the presence of less dense arboreal vegetation around the lake. These fluctuations reflect changes in quality and quantity of sedimentary organic matter linked to vegetation changes and the production of organic matter within the sedimentation basin connected with lake level variations. The combination of C/N and δ 13 C data on a cross-plot diagram shows a general distribution of points lying close to the planktonic (algal) organic matter. However, the scattering of certain points indicates a slight contribution from C 3 land plants. The variations in arboreal pollen (%AP) along the core are characterized by AP values between 40 and 80%. The 14C dating indicated Modern age at the shallow horizons to 1,030 years BP for the deeper horizon. (author)

Late Holocene monsoon climate as evidenced by proxy records from a lacustrine sediment sequence in western Guangdong, South China

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Zhong, Wei; Cao, jiayuan; Xue, Jibin; Ouyang, Jun; Tang, Xiaohong; Yin, Huanling; Liao, Congyun; Long, Kun

2014-02-01

The study of a 300-cm-thick exposed lacustrine sediment section in the Hedong village in Zhaoqing area which is located in sub-tropical west Guangdong Province in South China, demonstrates that the lacustrine sedimentary sequence possibly contains evidence for exploring variation of Asian monsoon climate. Multi-proxy records, including the humification intensity, total organic carbon, and grain size fractions, reveal a general trend towards dry and cold conditions in the late Holocene that this is because of a decrease in solar insolation on an orbital scale. Three intensified Asian summer monsoon (ASM) intervals (˜3300-3000 cal yr BP, ˜2600-1600 cal yr BP, and ˜900-600 cal yr BP), and three weakened ASM intervals (˜4000-3300 cal yr BP, ˜3000-2600 cal yr BP, and ˜1600-900 cal yr BP) are identified. Our humification record (HDcal) shows a good correlation on multi-centennial scale with the tree ring Δ14C record, a proxy of solar activity. A spectral analysis of HDcal reveals four significant cycles, i.e., ˜1250 yr, 300 yr, 110 yr, and 70 yr, and most of these cycles are related to the solar activity. Our findings indicate that solar output and oceanic-atmospheric circulation probably have influenced the late Holocene climate variability in the study region.

Empirical quantification of lacustrine groundwater discharge - different methods and their limitations

Science.gov (United States)

Meinikmann, K.; Nützmann, G.; Lewandowski, J.

2015-03-01

Groundwater discharge into lakes (lacustrine groundwater discharge, LGD) can be an important driver of lake eutrophication. Its quantification is difficult for several reasons, and thus often neglected in water and nutrient budgets of lakes. In the present case several methods were applied to determine the expansion of the subsurface catchment, to reveal areas of main LGD and to identify the variability of LGD intensity. Size and shape of the subsurface catchment served as a prerequisite in order to calculate long-term groundwater recharge and thus the overall amount of LGD. Isotopic composition of near-shore groundwater was investigated to validate the quality of catchment delineation in near-shore areas. Heat as a natural tracer for groundwater-surface water interactions was used to find spatial variations of LGD intensity. Via an analytical solution of the heat transport equation, LGD rates were calculated from temperature profiles of the lake bed. The method has some uncertainties, as can be found from the results of two measurement campaigns in different years. The present study reveals that a combination of several different methods is required for a reliable identification and quantification of LGD and groundwater-borne nutrient loads.

Lacustrine wetland in an agricultural catchment: nitrogen removal and related biogeochemical processes

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R. Balestrini

2008-03-01

Full Text Available The role of specific catchment areas, such as the soil-river or lake interfaces, in removing or buffering the flux of N from terrestrial to aquatic ecosystems is globally recognized but the extreme variability of microbiological and hydrological processes make it difficult to predict the extent to which different wetlands function as buffer systems. In this paper we evaluate the degree to which biogeochemical processes in a lacustrine wetland are responsible for the nitrate removal from ground waters feeding Candia Lake (Northern Italy. A transect of 18 piezometers was installed perpendicular to the shoreline, in a sub-unit formed by 80 m of poplar plantation, close to a crop field and 30 m of reed swamp. The chemical analysis revealed a drastic NO₃^–-N ground water depletion from the crop field to the lake, with concentrations decreasing from 15–18 mg N/l to the detection limit within the reeds. Patterns of Cl^–, SO₄^2–, O₂, NO₂^–-N, HCO₃^– and DOC suggest that the metabolic activity of bacterial communities, based on the differential use of electron donors and acceptors in redox reactions is the key function of this system. The significant inverse relationship found between NO₃^–-N and HCO₃^– is a valuable indicator of the denitrification activity. The pluviometric regime, the temperature, the organic carbon availability and the hydrogeomorphic properties are the main environmental factors affecting the N transformations in the studied lacustrine ecosystem.

Comparación ambiental, mediante registros sedimentarios, entre las condiciones prehispánicas y actuales de un sistema lacustre Environmental comparison, through sedimentary records, between pre-Hispanic and current conditions of a lacustrine system

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MARCO CISTERNAS

2000-03-01

Pedro lacustrine system (Laguna Grande and Chica. Chronological (C14, pollen and diatom analysis of superior and inferior layers of the cores were carried out. The results indicate that the San Pedro lacustrine system has undergone drastic changes since Spanish settlement. Evolving from a natural vegetation, predominantly native, to an intense pressure of forestry use. In the same way, the qualitative water state presents a variation in its trophic features, showing a evolution from oligotrophic to eutrophic waters in Laguna Grande and from oligotrophic to mesotrophic in Laguna Chica. Finally, it is suggested the incorporation of sedimentary records analysis in the study of environmental impact and management of lakes. In this way, it will be possible to know the background (the existing pre-Hispanic conditions and the response of aquatic ecosystem to the human influences

Drowning unconformity of lacustrine rift basins: A case study from the Dongying Sag in Bohai Bay Basin, China

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Chen, R.; Fan, J.

2015-12-01

The concept of drowning unconformity of lacustrine rift basins was proposed in this paper. This paper utilized 3D seismic data, well-log and the principles methods associated with structural geology, sedimentology and geochemistry, to analyze the drowning unconformity and discuss the origins of drowning unconformity in Dongying Sag in Bohai Bay Basin.Researching on it is not only important for a better understanding of tectonic evolution, palaeogeography and sedimentation of hydrocarbon source rocks, but also a vital guiding significance for the exploration of beach-bar sandstone reservoirs and shale oil.1. The concept of drowning unconformity of lacustrine rift basins is defined. With the consequences of rapid tectonic subsidence in basin, the sharp rise of lake-level and the increased rate of accommodation(A) in basin exceeded the rate of sediment supply(S),namely A>>S, the basin suddenly transformed into deep-water settings from shallow-water settings with sudden change of sediment transport and sediment dispersal patterns. 2.The sequence surface between Sha4 and Sha3 Member of Shahejie Formation is the drowning unconformity(43.5Ma). There are the sedimentary association of the reefs in shallow lacustrine, beach-bar sandstones and glutenite fan bodies under the surface. By contrast, there are the sedimentary association of deep-lake oil shales and shales over the surface. The drowning unconformity in Dongying Sag is a tectonic revolution surface which is changed from extensional tectonics to transtensional tectonics and it is also the surface of discontinuity from shallow lacustrine to deep lacustrine. The responses to sudden changes appeared in the parameters of geophysics, geochemistry and paleontology. 3. With the penetration of India into Asia plate in NNE trending,the subduction zones of Pacific Plate retreated. It caused the rapid downwelling of asthenospheric mantle, followed by the extensive drowning unconformity.

A note on coarse-grained gravity-flow deposits within proterozoic lacustrine sedimentary rocks, Transvaal sequence, South Africa

Science.gov (United States)

Eriksson, P. G.

A widely developed, thin, coarse-matrix conglomerate occurs within early Proterozoic lacustrine mudrocks in the Transvaal Sequence, South Africa. The poorly sorted tabular chert clasts, alternation of a planar clast fabric with disorientated zones, plus normal and inverse grading in the former rock type suggest deposition by density-modified grain-flow and high density turbidity currents. The lower fan-delta slope palæenvironment inferred for the conglomerate is consistent with the lacustrine interpretation for the enclosing mudrock facies. This intracratonic setting contrasts with the marine environment generally associated with density-modified grain-flow deposits.

Variationally Asymptotically Stable Difference Systems

Directory of Open Access Journals (Sweden)

Goo YoonHoe

2007-01-01

Full Text Available We characterize the h-stability in variation and asymptotic equilibrium in variation for nonlinear difference systems via n∞-summable similarity and comparison principle. Furthermore we study the asymptotic equivalence between nonlinear difference systems and their variational difference systems by means of asymptotic equilibria of two systems.

Dynamics of nonholonomic systems from variational principles embedded variation identity

International Nuclear Information System (INIS)

Guo Yongxin; Liu Shixing; Liu Chang; Chang Peng

2009-01-01

Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

The Alleret Maar lacustrine sequence (French Massif Central): a 150 ka long early-middle Pleistocene continental paleoenvironmental record.

Science.gov (United States)

Nomade, S.; Pastre, J.; Guillou, H.; Gauthier, A.; Scaillet, S.

2008-12-01

Lacustrine maar sequences of the French Massif Central are of great interest for paleoclimatic and paleoenvironmental reconstructions of mid-latitudes Quaternary continental environments. In particular, the western Velay region yields exceptional sequences spanning the last 450 ka (Reille et al., J. Quat. Sci. 2000). However, older sequences remain largely unknown despite the presence of interbedded alkaline tephras allowing precise absolute radiochronological control of many lacustrine squences. The Alleret maar is a 1500 m wide phreatomagmatic crater that provides a long lacustrine sequence (41 m). The upper part of this sequence (AL2 core, 14.6 m) was studied between 2005 and 2006 (Pastre et al., C. R. Acad Sci, 2007). A 39Ar/40Ar date (557 ± 5ka) obtained from an interbedded tephra layer located at 7m as well as the associated pollen data attribute the beginning of this sequence to the MIS 15. Thanks to the AL3 core recovered in 2005 (40.6 m, CNRS Meudon) several new tephra layers were discovered in the bottom part of this lacustrine sequence. Three new 39Ar/40Ar ages (single crystal analyses) from trachytic tephra layers were obtained at the LSCE Argon Laboratory (France). These layers are located at -30.2, -36.2 and -39.2m. Ages obtained relative to the ACR-2 flux standard (1,201Ma, Kuiper et al., Science, 2008) range from 692 ± 6 ka (MSWD: 2.3, n=18) for the youngest (-30.2m) to 726 ± 9Ka Ka (MSWD: 2.2, n=12) for the lowest tephra located at -39.2m. These new dates indicate a relatively homogeneous deposition rate of 3.5cm/ka and that the last 10 meters cover the MIS 17-MIS18 period. According to these current radiochronological data the complete lacustrine sequence last more than 150ka. Ongoing sedimentary and pollen studies will allow to extend the paleoenvironmental and paleoclimatic records of the French Massif Central towards the beginning of the early middle Pleistocene.

Dynamics of nonholonomic systems from variational principles embedded variation identity

Energy Technology Data Exchange (ETDEWEB)

Guo Yongxin, E-mail: yxguo@lnu.edu.c [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Shixing [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Chang; Chang Peng [Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081 (China)

2009-10-19

Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

Observations on the relation between lacustrine facies and uranium deposits in continental sediments

International Nuclear Information System (INIS)

Noble, E.A.

1981-01-01

A recent sedimentological concept and approach in the evaluation of lacustrine deposition environments for their geological uranium potential are described. The presence of certain types of limonite seems to be a key factor in the process of leaching, the formation of pyrite and the precipitation of uranium. (author)

Characterization of Tertiary Catalan lacustrine oil shales: Discovery of extremely organic sulphur-rich Type I kerogens

Science.gov (United States)

Sinninghe Damsté, Jaap S.; de las Heras, F. Xavier C.; van Bergen, Pim F.; de Leeuw, Jan W.

1993-01-01

The kerogens of three Tertiary Catalan lacustrine oil shales were analyzed by light microscopy, flash pyrolysis-gas chromatography-mass spectrometry, and bulk composition methods (elemental analysis, Rock Eval pyrolysis). Two of the three kerogens (Ribesalbes and Campins) are extremely rich in organic sulphur (atomic S org/C ratio > 0.04) and hydrogen (atomic ratio H/C ratio > 1.5) and are, consequently, classified as Type I-S kerogens. Very characteristic distribution patterns of flash pyrolysis products (e.g., alkan-9- and -10-ones, alkadienes) of the Ribesalbes kerogen revealed that it is predominantly composed of fossilized organic matter of the freshwater alga Botryococcus braunii. These two findings demonstrate that sulphurization of organic matter may also occur in lacustrine sediments provided that sulphate is supplied by external sources. Data on the third kerogen sample (Cerdanya) suggest that the freshwater alga Pediastrum may contain a (partly) aromatic biomacromolecule that is selectively preserved upon diagenesis. These findings testify to the large variability in palaeodepositional conditions in lacustrine environments. A comparison of the biomarker composition of the extract of the Ribesalbes oil shale with the kerogen composition indicate that biomarkers often cannot be used to assess the major sources of organic matter in such settings. A similar conclusion can be drawn from a comparison of literature data concerning the Messel Oil Shale.

Geomagnetic secular variation from recent lake sediments, ancient fireplaces and historical measurements in southeastern Australia

Science.gov (United States)

Barton, C. E.; Barbetti, Mike

1982-07-01

Compilations of historical observations, archaeomagnetic data from ancient fireplaces and palaemagetic results from short cores of sediment from lakes in southeastern Australia, particularly Lake Keilambete, provide a detailed record of the geomagnetic secular variation during the last 3000 years. The independent sets of data are in good agreement if the radiocarbon time scale for the lacustrine record is about 450 years too old. The error is attributed to systematic incorporation of ancient carbon into the lake floor sediments, mainly through erosion of sediment on the crater walls at times of low water level. A significant lag between deposition and the acquisition of stable magnetic remanence is ruled out. Inclination has been abnormally steep during the last 500 years but remained fairly close to the axial dipole field value prior to that. During the last 1000 years the predominant sense of looping of the magnetic vector corresponds to westward drift of the nondipole field. Secular variations on a time scale of ˜ 100 years can be resolved by the lacustrine record.

Lacustrine sedimentation and facies model for the last 45,000 yr in Chalco basin. Central Mexico

Science.gov (United States)

Ortega, B.; Lozano, S.; Caballero, M.; Herrera, D.

2013-05-01

Chalco basin in central Mexico (19° 15' N, 98° 58' W, 2200 m asl) is one of the most detailed lake sediment sequence analyzed in Mexico for paleoclimatic and paleoenvironmental studies. In this former lake, five drill cores up to 27 m depth were recovered in 1987-1989 by the UNAM team, and three cores covering most of the former sequence were obtained in 2008 and 2011. The upper 27 m of the Chalco lacustrine sequence contains the record of the last 45 kyr climate history in the northern American tropics. The active tectonic and volcanic setting of Chalco Lake in the Trans-Mexican Volcanic Belt, provides an opportunity to evaluate environmental (volcanic + tectonic vs. climatic) controls on lacustrine sedimentation. The establishment of a detailed time scale by 14C in pollen extracts provides an accurate chronological control. The stratigraphical and sedimentological analyses presented here provided the recognition of depositional environments and the architecture of the upper lacustrine succession. Sedimentary facies were defined on the basis of sedimentological descriptions, microscopic observation and compositional analyses. According to compositional criteria, facies were identified and groped into two main categories according to compositional criteria: 1) detrital and volcaniclastic, and 2) biogenic facies. The clastic facies includes massive to laminated, silty and clayey sediments composed of clay minerals, feldspars, amphiboles with minor amounts of quartz, opaque minerals and calcite. Diatoms are the most common biological remains in all the clastic facies. Most of the volcaniclastic deposits correspond to fall-out deposits, some of them of well documented eruptions of the nearby large stratovolcanoes Popocatepetl and Nevado de Toluca, which in turn serve as stratigraphical markers. The biogenic facies are massive to finely laminated diatom ooze and ostracod ooze layers. The sedimentary architecture of the lacustrine succession has been controlled by

Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi)

Science.gov (United States)

Sheryl Coombs; Gary D. Grossman

2006-01-01

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities...

Small-scale lacustrine drifts in Lake Champlain, Vermont

Science.gov (United States)

Manley, Patricia L.; Manley, T.O.; Hayo, Kathryn; Cronin, Thomas

2012-01-01

High resolution CHIRP (Compressed High Intensity Radar Pulse) seismic profiles reveal the presence of two lacustrine sediment drifts located in Lake Champlain's Juniper Deep. Both drifts are positive features composed of highly laminated sediments. Drift B sits on a basement high while Drift A is built on a trough-filling acoustically-transparent sediment unit inferred to be a mass-transport event. These drifts are oriented approximately north–south and are parallel to a steep ridge along the eastern shore of the basin. Drift A, located at the bottom of a structural trough, is classified as a confined, elongate drift that transitions northward to become a system of upslope asymmetric mudwaves. Drift B is perched atop a structural high to the west of Drift A and is classified as a detached elongate drift. Bottom current depositional control was investigated using Acoustic Doppler Current Profilers (ADCPs) located across Drift A. Sediment cores were taken at the crest and at the edges of the Drift A and were dated. Drift source, deposition, and evolution show that these drifts are formed by a water column shear with the highest deposition occurring along its crest and western flank and began developing circa 8700–8800 year BP.

Lacustrine Records of Holocene Mountain Glacier Fluctuations from Western Greenland

Science.gov (United States)

Schweinsberg, A.; Briner, J. P.; Bennike, O.

2014-12-01

Recent studies have focused on documenting fluctuations of the Greenland Ice Sheet margin throughout the Holocene but few data exist that constrain past changes of local glaciers independent of the ice sheet. Our research combines proglacial lake sediment analysis with cosmogenic 10Be dating of Holocene moraines and radiocarbon dating of ice-cap-killed vegetation with an overall objective to use this multi-proxy approach to generate a detailed record of the coupled climate-glacier system through the Holocene. Here, we present lacustrine records of mountain glacier variability from continuous pro-glacial lake sediment sequences recovered from two glaciated catchments in northeastern Nuussuaq, western Greenland. We use radiocarbon-dated sediments from Sikuiui and Pauiaivik lakes to reconstruct the timing of advance and retreat of local glaciers. Sediments were characterized with magnetic susceptibility (MS), gamma density, Itrax XRF and visible reflectance spectroscopy at 0.2 cm intervals and sediment organic matter at 0.5 cm intervals. Basal radiocarbon ages provide minimum-age constraints on deglaciation from Sikuiui and Pauiaivik lakes of ~9.6 and 8.7 ka, respectively. Organic-rich gyttja from deglaciation until ~5.0 ka in Pauiaivik Lake suggests minimal glacial extent there while slightly elevated MS values from ~9.0 - 7.0 ka in Sikuiui Lake may reflect early Holocene glacial advances. Minerogenic sediment input gradually increases starting at ~5.0 ka in Pauiaivik Lake, which we interpret as the onset of Neoglaciation in the catchment. Furthermore, a distinct episode of enhanced glacial activity from ~4.0 - 2.2 ka in Sikuiui Lake may be correlative to a period of persistent snowline lowering evidenced by radiocarbon dates of ice-killed vegetation from nearby ice cap margins. Results from these lacustrine records and our ice-killed vegetation dataset suggest a middle Holocene onset of Neoglaciation ~5.0 - 4.0 ka in this region. We are supplementing these records

Heavy metal and trace elements in riparian vegetation and macrophytes associated with lacustrine systems in Northern Patagonia Andean Range.

Science.gov (United States)

Juárez, Andrea; Arribére, María A; Arcagni, Marina; Williams, Natalia; Rizzo, Andrea; Ribeiro Guevara, Sergio

2016-09-01

Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.

Luminescence dating of the lacustrine record of Vršac (Carpathian Basin, Serbia) - implications for a palaeoenvironmetal reconstruction

Science.gov (United States)

Klasen, N.; Zeeden, C.; Markovic, S.; Fischer, P.; Lehmkuhl, F.; Schulte, P.; Bösken, J.; Hambach, U.; Vött, A.

2017-12-01

The Carpathian Basin is one of the key areas to investigate the influence of the continental, Mediterranean and Atlantic climate interaction over Europe. The available Upper Pleistocene and Holocene geoarchives in the region are mainly loess-paleosol records. Long lacustrine records are sparse and do not always span the whole last glacial cycle. In the area around Vršac, we drilled a 10 m core to contribute to the palaeoenvironmental reconstruction of the Carpathian Basin. Electrical Resistivity Tomography (ERT) was used to find the best-suited drilling location. We applied luminescence and radiocarbon dating, because a robust chronology is important for the interpretation of the sedimentary record. Pulsed OSL measurements were carried out to identify the best sampling positions. We expect runoff from the catchment being the main source of the lacustrine sediments, because coarse fluvial input is absent. Knowledge about the depositional conditions is important in luminescence dating to evaluate partial bleaching prior to deposition, which may cause age overestimation. Therefore, we compared infrared stimulated luminescence (IRSL) signals with post infrared infrared stimulated luminescence (pIRIR) signals, which bleach at different rates. Estimation of a representative water content has major influence on the age estimate, but remains challenging in luminescence dating. We measured the present day water content as well as the saturation water content, to account for variations over time. Luminescence and radiocarbon ages differ greatly from each other. According to the laboratory experiments, luminescence dating was reliable and we conclude that radiocarbon ages were underestimated because of an intrusion of younger organic material. The initial results demonstrated the potential of the drill core. Integrating more proxy data will be useful to enhance the importance of the geoarchive at Vršac for a better understanding of the last glacial cycle in the Carpathian

Characterisation of Tertiary Catalan lacustrine oil shales: Discovery of extremely organic sulphur-rich type I kerogens

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Las Heras, F.X.C. de; Bergen, P.F. van; Leeuw, J.W. de

1993-01-01

The kerogens of three Tertiary Catalan lacustrine oil shales were analyzed by light microscopy, flash pyrolysis-gas chromatography-mass spectrometry, and bulk composition methods (elemental analysis, Rock Eval pyrolysis). Two of the three kerogens (Ribesalbes and Campins) are extremely rich in

Performance evaluation of nitrogen isotope ratio determination in marine and lacustrine sediments: An inter-laboratory comparison

NARCIS (Netherlands)

Bahlmann, E.; Bernasconi, S.M.; Bouillon, S.; Houtekamer, M.J.; Korntheuer, M.; Langenberg, F.; Mayr, C.; Metzke, M.; Middelburg, J.J.; Nagel, B.; Struck, U.; Voß, M.; Emeis, K.C.

2010-01-01

Nitrogen isotopes of organic matter are increasingly studied in marine biogeochemistry and geology, plant and animal ecology, and paleoceanography. Here, we present results of an inter-laboratory test on determination of nitrogen isotope ratios in marine and lacustrine sediments. Six different

Hydro-climatic changes since 13.000 years B.P. in eastern Tibet and north of Xinjiang (China). Approach using the study of some lacustrine records

International Nuclear Information System (INIS)

Assaraj, A.

1997-01-01

The aim of this study is to build the chronology of the medium and short term climatic changes that took place during the last glacial and Holocene periods using sedimentological and isotopic data obtained on cores from the Aibi lake (north of Xinjiang, China) and from the Madoi and Donxi lakes (eastern part of the Tibetan plateau). At Aibi, after the chemical, isotopic and physico-chemical characterization of the lake waters, and the sedimentological study of the laminae (granulometry and mineralogy) have been done, the measurements of 18 O and 13 C of the authigenous carbonates and of the thickness variations of laminae have evidenced the seasonal character of the laminae. The spectral analyses of the thickness variations indicate periodicities linked with the quasi-biennial oscillations (2 or 3 years) and with the solar cycles (10-11 years). East of the Tibetan plateau, the sedimentological and isotopic study of the cores from the Madoi and Donxi lakes show more humid and hot climate conditions during the lower and middle Holocene. The sedimentary record of lake Madoi show one or several lacustrine or fluvio-lacustrine phases after 13000-12000 years B.P. A high dryness period took place within the Younger Dryas chrono-zone. Since 10000 year B.P. the 3 lakes are filled with isotopically diluted waters. The last glacial-Holocene transition seems to be very sharp and located around 10000 years B.P. both in northern Xinjiang and eastern Tibet and confirm the results previously obtained in Qinghai and northern-Xinjiang. After the optimum hydrologic phase of the lower and middle Holocene, the come back of dryer conditions started at about 6000 or 5000 years B.P. and hydrological conditions became close to the present day ones since 3000 years B.P. (J.S.)

Uranium and diagenesis in evaporitic lacustrine mudstone of the Oligocene White River Group, Dawes County, Nebraska. Bulletin

International Nuclear Information System (INIS)

Dickinson, K.A.

1991-01-01

The Oligocene White River Group consists of the Chadron and the overlying Brule Formations in northwestern Nebraska. The Chadron Formation consists of alluvial and colluvial vitric mudstone beds, but in addition contains white persistent layers (purplish-white layers) that probably resulted from soil formation on vitric parent material. West of the current study area a basal sandstone facies of the Chadron is host rock for the Crow Butte uranium deposit. The Brule, which consists mostly of pedogenically altered alluvial and fluvial vitric mudstone deposits, contains a uraniferous lacustrine facies northwest of Chadron, Nebraska. Detrital minerals in rocks of the White River Group include quartz, feldspar, volcanic glass, smectite, and illite. Chemical precipitate minerals in the lacustrine facies are calcite, dolomite, and gypsum. Authigenic minerals include calcite, dolomite, gypsum, smectite, opal, chalcedony, together with oxidized uranium minerals

Chronology of Late Saalian and Middle Weichselian episodes of ice-free lacustrine sedimentation recorded in the Arumetsa section, southwestern Estonia

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Maris Rattas

2010-06-01

Full Text Available The information obtained from a 21 m thick open-pit section of silty-clayey sediments in the Arumetsa bedrock valley, southwestern Estonia, revealed that lacustrine to glaciolacustrine sedimentation at the site started prior to 151 ka ago and lasted to about the end of marine isotope stage 6 (MIS6 at 130 ka. Further down from the 151 ka age-level to the bottom of the buried valley there are ca 60 m of lacustrine fine-grained sediments, the age of which remains still unclear. The Late Saalian sediments at Arumetsa are discordantly overlain by Middle Weichselian clay, silt and sand, deposited between ca 44 and 37 ka ago. As testified by optically stimulated luminescence (OSL ages, and pollen and diatom record, the Middle Weichselian fine-grained sediments contain redeposited Holsteinian but no Eemian pollen, and have not been fully bleached during deposition. Chronological, microfossil and sedimentological data show two hiatuses in the Arumetsa section. The first hiatus has left no sedimentary evidence for the period between ca 130 ka and 44 ka ago (MIS5 to older half of MIS3. The younger hiatus from ca 37 to 22 ka occurs between the Middle Weichselian lacustrine silt and the Late Weichselian till layer on top of the section.

Palaeoenvironmental implications of a Holocene sequence of lacustrine-peat sediments from the desert-loess transitional zone in Northern China

Science.gov (United States)

Jia, Feifei; Lu, Ruijie; Liu, Xiaokang; Zhao, Chao; Lv, Zhiqiang; Gao, Shangyu

2018-05-01

A high-resolution lacustrine-peat record from the desert-loess transitional zone in Northern China was obtained to reconstruct Holocene environmental change in the region. AMS 14C dates are used to provide a chronology. The results indicate that the site was a desert environment before 12.2 cal kyr BP, and was then occupied by a paleolake which started to shrink, with a wetland occurring from 6.2 to 3.0 cal kyr BP. Subsequently, the site became a seasonally water-filled depression. Based on the lithology and measurements of grain size and total organic carbon content, the climate changed from arid to humid at 12.2 cal kyr BP, and became more humid after 8.3 cal kyr BP. From 6.2 to 3.0 cal kyr BP, precipitation decreased but the climate remained at an optimum. After 3.0 cal kyr BP, the climate was dry overall but with several humid intervals. A comparison of paleoclimatic records from lacustrine and aeolian deposits from the region reveals a discrepancy about the nature of the early Holocene climate, and we conclude that this is because lacustrine sediments responded more sensitively to precipitation than aeolian deposits when the temperature was low. The environmental evolution of the region was synchronous with changes in the Asian summer monsoon (ASM), but temperature also played a key role in the early Holocene.

Classification and sedimentary characteristics of lacustrine hyperpycnal channels: Triassic outcrops in the south Ordos Basin, central China

Science.gov (United States)

Xian, Benzhong; Wang, Junhui; Gong, Chenglin; Yin, Yu; Chao, Chuzhi; Liu, Jianping; Zhang, Guodong; Yan, Qi

2018-06-01

Subaquatic channels are known as active conduits for the delivery of terrigenous sediments into related marine and lacustrine basins, as well as important targets for hydrocarbon exploration. Compared to submarine channels, lacustrine subaqueous channels created by hyperpycnal flows are understudied. Using well-exposed outcrops collected from three different locations in the southern Ordos Basin, central China, morphologies and architecture of a channelized hyperpycnal system were studied and classified. Six facies associations represent sedimentary processes from strong erosion by bedload dominated hyperpycnal flows, to transitional deposition jointly controlled by bedload and suspended-load dominated hyperpycnal flows, finally to deposition from suspended-load dominated hyperpycnal flows. On the basis of channel morphologies, infilling sediments and sedimentary processes, the documented channels can be classified into four main categories, which are erosional, bedload dominated, suspended-load dominated, and depositional channels. In very proximal and very distal locations, erosional channels and depositional channels serve as two end-members, while in middle areas, bedload-dominated channels and suspended-load dominated channels are transitional types. Erosional channels, as a response to strong erosion from bedload dominated hyperpycnal flows on upper slope, were mainly filled by mud interbedded with thin sand beds. As flow energy decreases, bedload dominated channels develop on middle slopes, which are characterized mainly by under- to balanced sediment infillings with cross-bedded sandstones and/or minor massive sandstones. Compared to bedload dominated channels, suspended-load dominated channels mainly develop in deeper water, and were filled mainly by massive or planar-laminated sandstones. Depositional channels, as a response to suspended-load dominated hyperpycnal flows in deep-water areas, are characterized by thin-medium bed classical turbidites with

Genesis and distribution pattern of carbonate cements in lacustrine deep-water gravity-flow sandstone reservoirs in the third member of the Shahejie Formation in the Dongying Sag, Jiyang Depression, Eastern China

DEFF Research Database (Denmark)

Yang, Tian; Cao, Yingchang; Friis, Henrik

2018-01-01

The lacustrine deep-water gravity-flow sandstone reservoirs in the third member of the Shahejie Formation are the main exploration target for hydrocarbons in the Dongying Sag, Eastern China. Carbonate cementation is responsible for much of the porosity and permeability reduction in the lacustrine...

A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars

Science.gov (United States)

Grotzinger, J. P.; Sumner, D. Y.; Kah, L. C.; Stack, K.; Gupta, S.; Edgar, L.; Rubin, D.; Lewis, K.; Schieber, J.; Mangold, N.; Milliken, R.; Conrad, P. G.; DesMarais, D.; Farmer, J.; Siebach, K.; Calef, F.; Hurowitz, J.; McLennan, S. M.; Ming, D.; Vaniman, D.; Crisp, J.; Vasavada, A.; Edgett, K. S.; Malin, M.; Blake, D.; Gellert, R.; Mahaffy, P.; Wiens, R. C.; Maurice, S.; Grant, J. A.; Wilson, S.; Anderson, R. C.; Beegle, L.; Arvidson, R.; Hallet, B.; Sletten, R. S.; Rice, M.; Bell, J.; Griffes, J.; Ehlmann, B.; Anderson, R. B.; Bristow, T. F.; Dietrich, W. E.; Dromart, G.; Eigenbrode, J.; Fraeman, A.; Hardgrove, C.; Herkenhoff, K.; Jandura, L.; Kocurek, G.; Lee, S.; Leshin, L. A.; Leveille, R.; Limonadi, D.; Maki, J.; McCloskey, S.; Meyer, M.; Minitti, M.; Newsom, H.; Oehler, D.; Okon, A.; Palucis, M.; Parker, T.; Rowland, S.; Schmidt, M.; Squyres, S.; Steele, A.; Stolper, E.; Summons, R.; Treiman, A.; Williams, R.; Yingst, A.; MSL Science Team; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Cremers, David; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Blank, Jennifer; Weigle, Gerald; Li, Shuai; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Brunet, Claude; Hipkin, Victoria; Léveillé, Richard; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Cécile; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Forni, Olivier; Gasnault, Olivier; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Sutter, Brad; Cabane, Michel; Coscia, David; Szopa, Cyril; Robert, François; Sautter, Violaine; Le Mouélic, Stéphane; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; Clegg, Sam; Cousin, Agnès; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Fay, Donald; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Dyar, M. Darby; Fassett, Caleb; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Bleacher, Lora; Brinckerhoff, William; Choi, David; Dworkin, Jason P.; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Posner, Arik; Voytek, Mary; Aubrey, Andrew; Behar, Alberto; Blaney, Diana; Brinza, David; Christensen, Lance; DeFlores, Lauren; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Jun, Insoo; Keymeulen, Didier; Mischna, Michael; Morookian, John Michael; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Morris, Richard V.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Vicenzi, Edward; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Clark, Benton; Wolff, Michael; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Schwenzer, Susanne P.; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Kortmann, Onno; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; Campbell, John L.; Perrett, Glynis; Pradler, Irina; VanBommel, Scott; Jacob, Samantha; Owen, Tobias; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; Bridges, John C.; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Gordon, Suzanne; Ollila, Ann; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

2014-01-01

The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.

Molecular isotopic characterisation of hydrocarbon biomarkers in Palaeocene-Eocene evaporitic, lacustrine source rocks from the Jianghan Basin, China

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Grice, Kliti; Schouten, S.; Peters, Kenneth E.

1998-01-01

Immature organic matter in lacustrine source rocks from the Jianghan Basin, eastern China, was studied for distributions and stable carbon isotopic compositions (13C) of hydrocarbon biomarkers. All of the bitumens contain isorenieratane (13C ca. −17 ) indicating the presence of Chlorobiaceae, and

Predominance of even carbon-numbered n-alkanes from lacustrine sediments in Linxia Basin, NE Tibetan Plateau: Implications for climate change

International Nuclear Information System (INIS)

Wang Yongli; Fang Xiaomin; Zhang Tongwei; Li Yuanmao; Wu Yingqin; He Daxiang; Wang Youxiao

2010-01-01

Research highlights: → This study reports the first observation of predominant even carbon-numbered n-alkanes of sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. → Certain types of special autochthonous bacteria are a possible source for the special distribution of even carbon-numbered n-alkanes in lacustrine sediments. → These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change. → A close correspondence among the low ratio of n-C 27 /n-C 31 , the heavy δ 13 C values of TOC and a strong even carbon-number predominance (low OEP 16-20 values) from approximately 6.5 to 4.4 Ma and at approximately 8 Ma in the studied section suggests that n-alkanes with a high predominance of even carbon-numbers may be treated as geochemical proxies for arid climate. - Abstract: This study reports the first observation of predominant even C-numbered n-alkanes from sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. The n-alkanes showed a bimodal distribution that is characterised by a centre at n-C 16 -n-C 20 with maximum values at n-C 18 and n-C 27 -n-C 31 as well as at n-C 29 . The first mode shows a strong even C-number predominance (OEP 16-20 0.34-0.66). In contrast, the second mode has a strong odd C-number predominance (OEP 27-31 1.20-2.45). Certain types of special autochthonous bacteria are a possible source for this distribution of even C-numbered n-alkanes in lacustrine sediments. These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change.

Truce with oxygen - A naerobiosis outcompete aerobiosis in the Antarctic lacustrine bacteria

Digital Repository Service at National Institute of Oceanography (India)

LokaBharathi, P.A.; Nair, S.; DeSouza, M.J.B.D.; Chandramohan, D.

. All colonies that were not black by sulfide precipitation were counted as FB. The anaerobic CFU were AnB, FB, SRB, and TDLO. The plates were incubated at 8–10° C for 10–20 days and the tubes for ca 30 days. All samples have been analysed... aerobiosis in the Antarctic lacustrine bacteria Page 3 of 5 file://C:\\My Documents\\articles23.htm 2/11/05 sulfide (63–188 ppm) at 5° C for 16 h and the viability estimated using Kogure’s method10,11. Viability is expressed as percentage of total viable...

Geophysical imaging of the lacustrine sediments deposited in the La Calderilla Volcanic Caldera (Gran Canaria Island, Spain) for paleoclimate research

Science.gov (United States)

Himi, Mahjoub; Rodríguez-González, Alejandro; Criado, Constantino; Tapias, Josefina C.; Ravazzi, Cesare; Pérez-Torrado, Francisco; Casas, Albert

2016-04-01

The discovery of well-preserved maar structures is important not only for studying the eruptive activity and formation of volcanoes, but also for paleoclimate research, since laminated maar lake sediments may contain very detailed archives of climate and environmental history. Maars are a singular type of volcanic structure generated by explosive phreatomagmatic eruptions as a result of interaction between rising magma and groundwater. This kind of structures are characterised by circular craters, often filled with water and/or lacustrine sediments and surrounded by a ring of pyroclastic deposits.Recently a borehole was drilled at the bottom of La Calderilla volcanic complex which penetrated about 8.7 m in its sedimentary sequence and paleobotanical study has supplied the first evidence of paleoenvironmental evolution during the Holocene on the Gran Canaria Island. This survey, however, did not penetrate into the substrate because the total thickness of the sedimentary fill was unknown. Since the age of formation of La Calderilla volcanic complex based on K/Ar dating is about 85,000 years (Upper Pleistocene), the possibility of its sedimentary fill extends beyond of the Holocene is extremely attractive, since, for example, there are few paleoenvironmental data regarding how much the last glaciation that affected the Canary Islands. In these circumstances, the knowledge of the total thickness of the lacustrine sediments is crucial to design a deeper borehole in the next future. Therefore, the subsurface characterisation provided by geophysics is essential for determining thickness and geometry of the sedimentary filling. Multielectrode ERT method was used to obtain five 2-D resistivity cross-sections into La Calderilla volcanic caldera. An Iris Syscal Pro resistivity system with 48 electrodes connected to a 94 m long cable (2m electrode spacing) in Wenner-Schlumberger configuration for an investigation depth of about 20 m. Data quality (q Current injected was

Architecture and reservoir quality of low-permeable Eocene lacustrine turbidite sandstone from the Dongying Depression, East China

Science.gov (United States)

Munawar, Muhammad Jawad; Lin, Chengyan; Chunmei, Dong; Zhang, Xianguo; Zhao, Haiyan; Xiao, Shuming; Azeem, Tahir; Zahid, Muhammad Aleem; Ma, Cunfei

2018-05-01

The architecture and quality of lacustrine turbidites that act as petroleum reservoirs are less well documented. Reservoir architecture and multiscale heterogeneity in turbidites represent serious challenges to production performance. Additionally, establishing a hierarchy profile to delineate heterogeneity is a challenging task in lacustrine turbidite deposits. Here, we report on the turbidites in the middle third member of the Eocene Shahejie Formation (Es3), which was deposited during extensive Middle to Late Eocene rifting in the Dongying Depression. Seismic records, wireline log responses, and core observations were integrated to describe the reservoir heterogeneity by delineating the architectural elements, sequence stratigraphic framework and lithofacies assemblage. A petrographic approach was adopted to constrain microscopic heterogeneity using an optical microscope, routine core analyses and X-ray diffraction (XRD) analyses. The Es3m member is interpreted as a sequence set composed of four composite sequences: CS1, CS2, CS3 and CS4. A total of forty-five sequences were identified within these four composite sequences. Sand bodies were mainly deposited as channels, levees, overbank splays, lobes and lobe fringes. The combination of fining-upward and coarsening-upward lithofacies patterns in the architectural elements produces highly complex composite flow units. Microscopic heterogeneity is produced by diagenetic alteration processes (i.e., feldspar dissolution, authigenic clay formation and quartz cementation). The widespread kaolinization of feldspar and mobilization of materials enhanced the quality of the reservoir by producing secondary enlarged pores. In contrast, the formation of pore-filling authigenic illite and illite/smectite clays reduced its permeability. Recovery rates are higher in the axial areas and smaller in the marginal areas of architectural elements. This study represents a significant insight into the reservoir architecture and

Tephras in lacustrine sediments of the Sarliève marsh (French Massif Central): age and preservation

Science.gov (United States)

Fourmont, Agathe; Macaire, Jean-Jacques; Bréhéret, Jean-Gabriel; Argant, Jacqueline; Prat, Béatrice; Vernet, Gérard

2006-12-01

The Sarliève marsh sediments (Massif Central, France) contain two tephras. The first tephra [ 13.7±0.4ka(2δ), ca. 12 000 BP], regionally well known, enables to date the beginning of lacustrine infill to the Lateglacial. The second tephra, the 'tephra de Sarliève', the emitting volcano of which is unknown, would be dated to around the Early Subboreal from pollen data. This occurrence, after the discovery of the 'tephra de Beaunit', emphasizes that volcanic eruption(s) occurred in the 'Chaîne des Puys' or in the volcanic Cézallier more than 1000 years after the last known eruption (Pavin) in the 'Chaîne des Puys' at around 6.6/6.7 ka (5800/5900 BP). In the Sarliève piles, these tephras, well preserved in thick and more silicated deposits of deltas, were not observed in carbonated basin sediments where they were altered. The abundance of authigenic zeolites formed during the Lateglacial in restricted depocentre lacustrine waters allows us to detect initial CF1 tephra occurrence. To cite this article: A. Fourmont et al., C. R. Geoscience 338 (2006).

Disentangling natural and anthropogenic signals in lacustrine records: An example from the Ilan Plain, NE Taiwan

Directory of Open Access Journals (Sweden)

Jyh-Jaan Huang

2016-11-01

Full Text Available The impact of human activities has been increasing to a degree where humans now outcompete many natural processes. When interpreting environmental and climatic changes recorded in natural archives on historical time scales, it is therefore important to be able to disentangle the relative contribution of natural and anthropogenic processes. Lake Meihua on the Ilan Plain in northeastern Taiwan offers a particularly suitable opportunity to test how human activities known from historical records can be recorded in lacustrine sediment. For this purpose, three cores from Lake Meihua have been studied by a multiproxy approach, providing the first decadal-resolution lacustrine records covering the past 150 years in Taiwan. Profiles of excess 210Pb, 137Cs and 239,240Pu from two short cores (MHL-09-01 and MHL-11-02 allowed a precise chronology to be established. The presence of a yellow, earthy layer with lower levels of organic material coincide with the record of land development associated with the construction of the San-Chin-Gong Temple during AD 1970-1982. Furthermore, in the lower part of the cores, the upwards increasing trend of inc/coh, TOC, TOC/TN, and grain size, coupled with the palynological data (increase of Alnus, Mallotus, Trema and herbs from the nearby core MHL-5A with radiocarbon chronology, suggest that the area surrounding the lake has been significantly affected by agricultural activities since the arrival of Chinese settlers around ~AD 1874. In sum, this study demonstrates that this suite of lacustrine sediments in northeastern Taiwan has recorded human activities in agreement with historical documents, and that different human activities will leave distinct sedimentological, geochemical, and palynological signatures in the sedimentary archives. Therefore, multiproxy reconstructions are important to capture the complex nature of human-environmental interactions. A better understanding of the weathering and erosion response to human

Disentangling natural and anthropogenic signals in lacustrine records: An example from the Ilan Plain, NE Taiwan

Science.gov (United States)

Huang, Jyh-Jaan; Huh, Chih-An; Wei, Kuo-Yen; Löwemark, Ludvig; Lin, Shu-Fen; Liao, Wen-Hsuan; Yang, Tien-Nan; Song, Sheng-Rong; Lee, Meng-Yang; Su, Chih-Chieh; Lee, Teh-Quei

2016-11-01

The impact of human activities has been increasing to a degree where humans now outcompete many natural processes. When interpreting environmental and climatic changes recorded in natural archives on historical time scales, it is therefore important to be able to disentangle the relative contribution of natural and anthropogenic processes. Lake Meihua on the Ilan Plain in northeastern Taiwan offers a particularly suitable opportunity to test how human activities known from historical records can be recorded in lacustrine sediment. For this purpose, three cores from Lake Meihua have been studied by a multiproxy approach, providing the first decadal-resolution lacustrine records covering the past 150 years in Taiwan. Profiles of excess 210Pb, 137Cs and 239,240Pu from two short cores (MHL-09-01 and MHL-11-02) allowed a precise chronology to be established. The presence of a yellow, earthy layer with lower levels of organic material coincide with the record of land development associated with the construction of the San-Chin-Gong Temple during AD 1970-1982. Furthermore, in the lower part of the cores, the upwards increasing trend of inc/coh, TOC, TOC/TN, and grain size, coupled with the palynological data (increase of Alnus, Mallotus, Trema and herbs) from the nearby core MHL-5A with radiocarbon chronology, suggest that the area surrounding the lake has been significantly affected by agricultural activities since the arrival of Chinese settlers around AD 1874. In sum, this study demonstrates that this suite of lacustrine sediments in northeastern Taiwan has recorded human activities in agreement with historical documents, and that different human activities will leave distinct sedimentological, geochemical, and palynological signatures in the sedimentary archives. Therefore, multiproxy reconstructions are important to capture the complex nature of human-environmental interactions. A better understanding of the weathering and erosion response to human activities can

The relationship between humans and climate across the North Atlantic: what can lacustrine biomarkers tell us?

Science.gov (United States)

de Wet, G.; Castañeda, I. S.; Bradley, R. S.; Small, G.; Barrasso, T.

2016-12-01

While climate change has been implicated in the colonization/population dynamics of the North Atlantic region, researchers in many cases are forced to compare archaeological data with distant paleoclimate records, making these linkages tenuous. Our research utilizes novel organic biomarkers in lacustrine sediments to produce paired paleoclimate and human occupancy reconstructions to better address questions surrounding human migration and climate change. Here we present preliminary results from two prominent locations in the history of the European colonization of the North Atlantic. The first, carried out on the Norse "Eastern Settlement" in Southern Greenland, attempts to answer the long-standing question of whether climate change caused the demise of the colony in the 1400s C.E. Second, we use similar techniques to search for evidence of the first peopling of the Faroe Islands, a highly debated topic. The use of lacustrine biomarkers allows for numerous aspects of both paleoclimate and human presence in a catchment to be reconstructed. We reconstruct paleotemperatures using branched glycerol dialkyl glycerol tetraethers (brGDGTs) and alkenones (the UK37 Index), when present. Additionally, will analyze the difference in the hydrogen isotopic composition of long and short-chain plant leaf waxes as a proxy for lake water balance. Human occupancy in the region is investigated using fecal sterols and stanols, primarily created by the breakdown of cholesterol. Some of these compounds, such as coprostanol (the dominant sterol in human waste), provide strong evidence of human settlements and have been identified in some of our lake records. Our preliminary results suggest that temperatures were increasing in SW Greenland during the period when the Norse are thought to have died out, potentially challenging the long-standing view of climate deterioration being the primary cause of their demise. Primary productivity biomarkers from lake Eidisvatnet, in the Faroe Islands

Millennial-scale Climate Variations Recorded As Far Back As The Early Pliocene

Science.gov (United States)

Steenbrink, J.; Hilgen, F. J.; Lourens, L. J.

Quaternary climate proxy records show compelling evidence for climate variability on time scales of a few thousand years. The causes for these millennial-scale or sub- Milankovitch cycles are yet poorly understood, not in the least due to the complex feedback mechanisms of large ice-sheets during the Quaternary. We present evidence of millennial-scale climate variability in Early Pliocene lacustrine sediments from the intramontane Ptolemais Basin in northwestern Greece. The sediments are well ex- posed in a series of open-pit lignite mines and exhibit a distinct m-scale sedimentary cyclicity of alternating lignites and lacustrine marl beds that result from precession- induced variations in climate. A higher-frequency cyclicity is particular prominent within the marl segment of individual cycles. A stratigraphic interval of~115 kyr, cov- ering five precession-induced sedimentary cycles, was studied in nine parallel sections from two quarries located several km apart. Colour reflectance records were used to quantify the within-cycle variability and to determine its lateral continuity. Much of the within-cycle variability could be correlated between the parallel sections, even in fine detail, which suggests that these changes reflect basin-wide variations in environ- mental conditions related to (regional) climate fluctuations. Interbedded volcanic ash beds demonstrate the synchronicity of these fluctuations and spectral analysis of the reflectance time series shows a significant concentration of variability at periods of ~11,~5.5 and~2 kyr. Their occurrence at times before the intensification of the North- ern Hemisphere glaciation suggests that they cannot solely have resulted from internal ice-sheet dynamics. Possible candidates include harmonics or combination tones of the main orbital cycles, variations in solar output or periodic motions of the Earth and moon.

Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

Czech Academy of Sciences Publication Activity Database

Matys Grygar, Tomáš; Mach, K.

2013-01-01

Roč. 88, č. 3 (2013), s. 557-571 ISSN 1214-1119 R&D Projects: GA ČR(CZ) GAP210/11/1357 Institutional support: RVO:61388980 Keywords : Most Basin * Burdigalian * chemostratigraphy * proxy analyses * lacustrine sediments Subject RIV: DD - Geochemistry Impact factor: 1.495, year: 2013

Development and Rainfed Paddy Soils Potency Derived from Lacustrine Material in Paguyaman, Gorontalo

Directory of Open Access Journals (Sweden)

Nurdin

2011-09-01

Full Text Available Rainfed paddy soils that are derived from lacustrine and include of E4 agroclimatic zone have many unique properties and potentially for paddy and corn plantations. This sreseach was aimed to: (1 study the soil development of rainfed paddy soils derived from lacustrine and (2 evaluate rainfed paddy soils potency for paddy and corn in Paguyaman. Soil samples were taken from three profiles according to toposequent, and they were analyzed in laboratory. Data were analyzed with descriptive-quantitative analysis. Furthermore, assessment on rainfed paddy soils potency was conducted with land suitability analysis using parametric approach. Results indicate that all pedon had evolved with B horizons structurization. However, pedon located on the summit slope was more developed and intensely weathered than those of the shoulder and foot slopes.The main pedogenesis in all pedons were through elluviation, illuviation, lessivage, pedoturbation, and gleization processes. The main factors of pedogenesis were climate, age (time and topography factors. Therefore, P1 pedons are classified as Ustic Endoaquerts, fine, smectitic, isohypertermic; P2 as Vertic Endoaquepts, fine, smectitic, isohypertermic; and P3 as Vertic Epiaquepts, fine, smectitic, isohypertermic. Based on the potentials of the land, the highest of land suitability class (LSC of land utilization type (LUT local paddy was highly suitable (S1, while the lowest one was not suitable with nutrient availability as the limiting factor (Nna. The highest LCS of paddy-corn LUT was marginally suitable with water availability as the limiting factor (S3wa, while the lower LSC was not suitable with nutrient availabily as the limiting factor (Nna.

Predominance of even carbon-numbered n-alkanes from lacustrine sediments in Linxia Basin, NE Tibetan Plateau: Implications for climate change

Energy Technology Data Exchange (ETDEWEB)

Wang Yongli [Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000 (China)] [Institute of Tibetan and Plateau Research, Chinese Academy of Sciences, Beijing 100085 (China); Fang Xiaomin, E-mail: fangxm@itpcas.ac.cn [Institute of Tibetan and Plateau Research, Chinese Academy of Sciences, Beijing 100085 (China)] [Key Laboratory of Western Resources and Environment of Education Ministry, College at Earth and Environment Sciences, University of Lanzhou, Lanzhou 730000 (China); Zhang Tongwei [Key Laboratory of Western Resources and Environment of Education Ministry, College at Earth and Environment Sciences, University of Lanzhou, Lanzhou 730000 (China); Li Yuanmao; Wu Yingqin; He Daxiang; Wang Youxiao [Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2010-10-15

Research highlights: {yields} This study reports the first observation of predominant even carbon-numbered n-alkanes of sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. {yields} Certain types of special autochthonous bacteria are a possible source for the special distribution of even carbon-numbered n-alkanes in lacustrine sediments. {yields} These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change. {yields} A close correspondence among the low ratio of n-C{sub 27}/n-C{sub 31}, the heavy {delta}{sup 13}C values of TOC and a strong even carbon-number predominance (low OEP{sub 16-20} values) from approximately 6.5 to 4.4 Ma and at approximately 8 Ma in the studied section suggests that n-alkanes with a high predominance of even carbon-numbers may be treated as geochemical proxies for arid climate. - Abstract: This study reports the first observation of predominant even C-numbered n-alkanes from sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. The n-alkanes showed a bimodal distribution that is characterised by a centre at n-C{sub 16}-n-C{sub 20} with maximum values at n-C{sub 18} and n-C{sub 27}-n-C{sub 31} as well as at n-C{sub 29}. The first mode shows a strong even C-number predominance (OEP{sub 16-20} 0.34-0.66). In contrast, the second mode has a strong odd C-number predominance (OEP{sub 27-31} 1.20-2.45). Certain types of special autochthonous bacteria are a possible source for this distribution of even C-numbered n-alkanes in lacustrine sediments. These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded

Volcanic influence of Mt. Fuji on the watershed of Lake Motosu and its impact on the lacustrine sedimentary record

Science.gov (United States)

Lamair, Laura; Hubert-Ferrari, Aurélia; Yamamoto, Shinya; El Ouahabi, Meriam; Vander Auwera, Jacqueline; Obrochta, Stephen; Boes, Evelien; Nakamura, Atsunori; Fujiwara, Osamu; Shishikura, Masanobu; Schmidt, Sabine; Siani, Giuseppe; Miyairi, Yosuke; Yokoyama, Yusuke; De Batist, Marc; Heyvaert, Vanessa M. A.; QuakeRecNankai Team

2018-01-01

Lacustrine sediments are particularly sensitive to modifications within the lake catchment. In a volcanic area, sedimentation rates are directly affected by the history of the volcano and its eruptions. Here, we investigate the impact of Mt. Fuji Volcano (Japan) on Lake Motosu and its watershed. The lacustrine infill is studied by combining seismic reflection profiles and sediment cores. We show evidence of changes in sedimentation patterns during the depositional history of Lake Motosu. The frequency of large mass-transport deposits recorded within the lake decreases over the Holocene. Before 8000 cal yr BP, large sublacustrine landslides and turbidites were filling the lacustrine depression. After 8000 cal yr BP, only one large sublacustrine landslide was recorded. The change in sedimentation pattern coincides with a change in sediment accumulation rate. Over the last 8000 cal yr BP, the sediment accumulation rate was not sufficient enough to produce large sublacustrine slope failures. Consequently, the frequency of large mass-transport deposits decreased and only turbidites resulting from surficial slope reworking occurred. These constitute the main sedimentary infill of the deep basin. We link the change in sediment accumulation rate with (i) climate and vegetation changes; and (ii) the Mt. Fuji eruptions which affected the Lake Motosu watershed by reducing its size and strongly modified its topography. Moreover, this study highlights that the deposition of turbidites in the deep basin of Lake Motosu is mainly controlled by the paleobathymetry of the lakefloor. Two large mass-transport deposits, occurring around 8000 cal yr BP and 2000 cal yr BP respectively, modified the paleobathymetry of the lakefloor and therefore changed the turbidite depositional pattern of Lake Motosu.

An Investigation of Trace Elements in Marine and Lacustrine Deposits by Means of a Neutron Activation Method

Energy Technology Data Exchange (ETDEWEB)

Landstroem, O; Samsahl, K; Wenner, C G

1967-10-15

A neutron activation method for multi-elemental analysis was applied to argillaceous deposits from the Viskan Valley on the Swedish West Coast, an area in which transgressions and regressions of the sea have occurred during the postglacial time. These changes between fresh-water and marine stages are well known from earlier geologic investigations. Analysis could therefore be performed of samples of known marine (brackish) and lacustrine origin. In a preliminary test on four samples, taken from two marine layers and two lacustrine layers, altogether 30 elements were quantitatively determined, namely As, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hf, Hg, La, Lu, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, W, Yb, Zn and Zr. Several elements showed a difference in concentration between the marine and the fresh-water layers. Br, Hg, Mn, Se, As and Sb were more thoroughly investigated in three boreholes from different sections of the valley. Br and Se had high means in the most pronounced marine samples of the fiord deposits. Moreover, Mn showed a fourfold increase just in the transition stage between the older sea fiord and the older lage stage.

An Investigation of Trace Elements in Marine and Lacustrine Deposits by Means of a Neutron Activation Method

International Nuclear Information System (INIS)

Landstroem, O.; Samsahl, K.; Wenner, C.G.

1967-10-01

A neutron activation method for multi-elemental analysis was applied to argillaceous deposits from the Viskan Valley on the Swedish West Coast, an area in which transgressions and regressions of the sea have occurred during the postglacial time. These changes between fresh-water and marine stages are well known from earlier geologic investigations. Analysis could therefore be performed of samples of known marine (brackish) and lacustrine origin. In a preliminary test on four samples, taken from two marine layers and two lacustrine layers, altogether 30 elements were quantitatively determined, namely As, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hf, Hg, La, Lu, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, W, Yb, Zn and Zr. Several elements showed a difference in concentration between the marine and the fresh-water layers. Br, Hg, Mn, Se, As and Sb were more thoroughly investigated in three boreholes from different sections of the valley. Br and Se had high means in the most pronounced marine samples of the fiord deposits. Moreover, Mn showed a fourfold increase just in the transition stage between the older sea fiord and the older lage stage

Distinguishing megathrust from intraplate earthquakes using lacustrine turbidites (Laguna Lo Encañado, Central Chile)

Science.gov (United States)

Van Daele, Maarten; Araya-Cornejo, Cristian; Pille, Thomas; Meyer, Inka; Kempf, Philipp; Moernaut, Jasper; Cisternas, Marco

2017-04-01

One of the main challenges in seismically active regions is differentiating paleo-earthquakes resulting from different fault systems, such as the megathrust versus intraplate faults in subductions settings. Such differentiation is, however, key for hazard assessments based on paleoseismic records. Laguna Lo Encañado (33.7°S; 70.3°W; 2492 m a.s.l.) is located in the Central Chilean Andes, 50 km east of Santiago de Chile, a metropole with about 7,000,000 inhabitants. During the last century the study area experienced 3 large megathrust earthquakes (1906, 1985 and 2010) and 2 intraplate earthquakes (1945 and 1958) (Lomnitz, 1960). While the megathrust earthquakes cause Modified Mercalli Intensities (MMIs) of VI to VII at the lake (Van Daele et al., 2015), the intraplate earthquakes cause peak MMIs up to IX (Sepúlveda et al., 2008). Here we present a turbidite record of Laguna Lo Encañado going back to 1900 AD. While geophysical data (3.5 kHz subbottom seismic profiles and side-scan sonar data) provides a bathymetry and an overview of the sedimentary environment, we study 15 short cores in order to understand the depositional processes resulting in the encountered lacustrine turbidites. All mentioned earthquakes triggered turbidites in the lake, which are all linked to slumps in proximal areas, and are thus resulting from mass wasting of the subaquatic slopes. However, turbidites linked to the intraplate earthquakes are additionally covered by turbidites of a finer-grained, more clastic nature. We link the latter to post-seismic erosion of onshore landslides, which need higher MMIs to be triggered than subaquatic mass movements (Howarth et al., 2014). While intraplate earthquakes can cause MMIs up to IX and higher, megathrust earthquakes do not cause sufficiently high MMIs at the lake to trigger voluminous onshore landslides. Hence, the presence of these post-seismic turbidites allows to distinguish turbidites triggered by intraplate earthquakes from those

Giving perspective to cliff exposures with ground penetrating radar: Devonian lacustrine shore zone architecture

Science.gov (United States)

Andrews, Steven; Moreau, Julien; Archer, Stuart

2015-04-01

The orbitally-controlled cyclic lacustrine successions of the Middle Devonian in Northern Scotland contains repeated developments of shore zone sandstones. However, due to the cliff-forming nature of the succession and the attitude of the sections through these sandstones, interpretation of this facies has been problematic. To better understand the shore zone systems, we carried out very high resolution sedimentary logging and constructed photo-panels which were combined with high resolution GPR profiling (250 MHz). To ensure close ties between the sedimentary logs and the GPR data, the cliffs were accessed using rope access techniques while GPR grids were shot directly above. The profiles were shot mainly in the strike direction of what was thought to be the shore elongation every 5-10 m and every 20-30 m in the dip direction. Shore zone systems of 3 different sequences have been imaged for a total of 1155 m of GPR profile collected. This configuration has allowed 3D visualisation of the architecture of the shore zone systems and, in combination with detailed sedimentology, provided insights into the generation of the dynamic shore zone environments. The coastal cliffs of northern Scotland expose sedimentary cycles on average 16-m-thick which record deep lake, perennial lake and playa environments. The shore zone deposits reach 2 to 3.5 m in thickness. Loading and discrete channel forms are recognised in both the GPR data and sedimentary logs through the lower portion of the lake shore zone successions. Up-section the sandstone beds appear to become amalgamated forming subtle low angle accretionary bar complexes which although visible in outcrop, after careful investigation, can be fully visualised and examined in the GPR data. The 3D visualisation allowed mapping the architecture and distribution of the bars . The orientation of these features, recognised from the survey, is consistent with extensive palaeocurrent measurements from oscillation ripples. Further

High-resolution δ13C record of fossil wood and bulk organic matter from a deep Oligocene lacustrine succession, Bach Long Vi Island, Vietnam

Science.gov (United States)

Rizzi, M.; Schovsbo, N. H.; Fyhn, M. B. W.; Korte, C.

2017-12-01

We present a high-resolution stable isotope record based on bulk organic matter (δ13Corg) and fossil wood (δ13Cwood) originating from Oligocene deep lacustrine sediments cored on the Bach Long Vi Island, northern Gulf of Tonkin, offshore Vietnam. The sediments are exceptionally well preserved. They are thus excellently suited for a detailed stratigraphical analysis of the stable isotope record and as proxy for environmental and climatic changes within this period. The sediments were deposited in rapid subsiding, narrow and elongated fault-bound graben (Fyhn and Phach, 2015) and are represented by deep pelagic lacustrine organic-rich mud interrupted by numerous density-flow deposits (Hovikoski et al., 2016). The density-flow deposits contain abundant fragments of fossil wood. Therefore it was possible to obtain 262 coalified wood fragments together with 1063 bulk organic samples throughout the span of the core. This allowed to establish a high resolution stable C isotope record (δ13Corg and δ13Cwood). In addition 2464 handheld XRF determinations were carried out to further characterize the depositional environment (Rizzi et al., 2017). The organic carbon isotope trend from the 500 m core succession provides insight into the palaeoenvironmental changes of the lake during the Oligocene. Both, global and local factors control the δ13C variations. The aim of the study is to obtain pure global δ13Corg and δ13Cwood signals that would allow comparison of the studied sediments with coeval syn-rift successions in the South China Sea region and other parts of the world. [1] Fyhn and Phach (2015) Tectonics, 34(2): 290-312. [2] Hovikoski et al. (2016) Journal of Sedimentary Research, 86(8): 982-1007. [3] Rizzi et al. (2017) EGU General Assembly Abstract EGU 2017-17584.

Genetic basis for body size variation between an anadromous and two derived lacustrine populations of threespine stickleback Gasterosteus aculeatus in southwest Alaska.

Science.gov (United States)

Bowles, Ella; Johnston, Rebecca A; Vanderzwan, Stevi L; Rogers, Sean M

2016-02-01

Body size is a highly variable trait among geographically separated populations. Size-assortative reproductive isolation has been linked to recent adaptive radiations of threespine stickleback ( Gasterosteus aculeatus ) into freshwater, but the genetic basis of the commonly found size difference between anadromous and derived lacustrine sticklebacks has not been tested. We studied the genetic basis of size differences between recently diverging stickleback lineages in southwest Alaska using a common environment experiment. We crossed stickleback within one anadromous (Naknek River) and one lake (Pringle Lake) population and between the anadromous and two lake populations (Pringle and JoJo Lakes), and raised them in a salinity of 4-6 ppt. The F1 anadromous and freshwater forms differed significantly in size, whereas hybrids were intermediate or exhibited dominance toward the anadromous form. Additionally, the size of freshwater F1s differed from their wild counterparts, with within-population F1s from Pringle Lake growing larger than their wild counterparts, while there was no size difference between lab-raised and wild anadromous fish. Sexual dimorphism was always present in anadromous fish, but not in freshwater, and not always in the hybrid crosses. These results, along with parallel changes among anadromous and freshwater forms in other regions, suggest that this heritable trait is both plastic and may be under divergent and/or sexual selection.

Sedimentary architecture of a sub-lacustrine debris fan: Eocene Dongying Depression, Bohai Bay Basin, east China

Science.gov (United States)

Liu, Jianping; Xian, Benzhong; Wang, Junhui; Ji, Youliang; Lu, Zhiyong; Liu, Saijun

2017-12-01

The sedimentary architectures of submarine/sublacustrine fans are controlled by sedimentary processes, geomorphology and sediment composition in sediment gravity flows. To advance understanding of sedimentary architecture of debris fans formed predominantly by debris flows in deep-water environments, a sub-lacustrine fan (Y11 fan) within a lacustrine succession has been identified and studied through the integration of core data, well logging data and 3D seismic data in the Eocene Dongying Depression, Bohai Bay Basin, east China. Six types of resedimented lithofacies can be recognized, which are further grouped into five broad lithofacies associations. Quantification of gravity flow processes on the Y11 fan is suggested by quantitative lithofacies analysis, which demonstrates that the fan is dominated by debris flows, while turbidity currents and sandy slumps are less important. The distribution, geometry and sedimentary architecture are documented using well data and 3D seismic data. A well-developed depositional lobe with a high aspect ratio is identified based on a sandstone isopach map. Canyons and/or channels are absent, which is probably due to the unsteady sediment supply from delta-front collapse. Distributary tongue-shaped debris flow deposits can be observed at different stages of fan growth, suggesting a lobe constructed by debrite tongue complexes. Within each stage of the tongue complexes, architectural elements are interpreted by wireline log motifs showing amalgamated debrite tongues, which constitute the primary fan elements. Based on lateral lithofacies distribution and vertical sequence analysis, it is proposed that lakefloor erosion, entrainment and dilution in the flow direction lead to an organized distribution of sandy debrites, muddy debrites and turbidites on individual debrite tongues. Plastic rheology of debris flows combined with fault-related topography are considered the major factors that control sediment distribution and fan

Chemical variations in Yellowknife Bay formation sedimentary rocks analyzed by ChemCam on board the Curiosity rover on Mars

Science.gov (United States)

Mangold, Nicolas; Forni, Olivier; Dromart, G.; Stack, K.M.; Wiens, Roger C.; Gasnault, Olivier; Sumner, Dawn Y.; Nachon, Marion; Meslin, Pierre-Yves; Anderson, Ryan B.; Barraclough, Bruce; Bell, J.F.; Berger, G.; Blaney, D.L.; Bridges, J.C.; Calef, F.; Clark, Brian R.; Clegg, Samuel M.; Cousin, Agnes; Edgar, L.; Edgett, Kenneth S.; Ehlmann, B.L.; Fabre, Cecile; Fisk, M.; Grotzinger, John P.; Gupta, S.C.; Herkenhoff, Kenneth E.; Hurowitz, J.A.; Johnson, J. R.; Kah, Linda C.; Lanza, Nina L.; Lasue, Jeremie; Le Mouélic, S.; Lewin, Eric; Malin, Michael; McLennan, Scott M.; Maurice, S.; Melikechi, Noureddine; Mezzacappa, Alissa; Milliken, Ralph E.; Newsome, H.L.; Ollila, A.; Rowland, Scott K.; Sautter, Violaine; Schmidt, M.E.; Schroder, S.; D'Uston, C.; Vaniman, Dave; Williams, R.A.

2015-01-01

The Yellowknife Bay formation represents a ~5 m thick stratigraphic section of lithified fluvial and lacustrine sediments analyzed by the Curiosity rover in Gale crater, Mars. Previous works have mainly focused on the mudstones that were drilled by the rover at two locations. The present study focuses on the sedimentary rocks stratigraphically above the mudstones by studying their chemical variations in parallel with rock textures. Results show that differences in composition correlate with textures and both manifest subtle but significant variations through the stratigraphic column. Though the chemistry of the sediments does not vary much in the lower part of the stratigraphy, the variations in alkali elements indicate variations in the source material and/or physical sorting, as shown by the identification of alkali feldspars. The sandstones contain similar relative proportions of hydrogen to the mudstones below, suggesting the presence of hydrous minerals that may have contributed to their cementation. Slight variations in magnesium correlate with changes in textures suggesting that diagenesis through cementation and dissolution modified the initial rock composition and texture simultaneously. The upper part of the stratigraphy (~1 m thick) displays rocks with different compositions suggesting a strong change in the depositional system. The presence of float rocks with similar compositions found along the rover traverse suggests that some of these outcrops extend further away in the nearby hummocky plains.

Characterization of Tertiary Catalan lacustrine oil shales: Discovery of extrmely organic sulphur-rich Type I kerogens

Energy Technology Data Exchange (ETDEWEB)

Sinninghe Damste, J.S.; Heras, F.X.C. De Las; Bergen, P.F. Van; Leeuw, J.W. De (Delft Univ. of Technology (Netherlands))

1993-01-01

The kerogens of three Tertiary Catalan lacustrine oil shales were analyzed by light microscopy, flash pyrolysis-gas chromatography-mass spectrometry, and bulk composition methods (elemental analysis, Rock Eval pyrolysis). Two of the three kerogens (Ribesalbes and Campins) are extremely rich in organic sulfur (atomic S[sub org]/C ratio > 0.04) and hydrogen (atomic ratio H/C ratio > 1.5) and are, consequently, classified as Type I-S kerogens. Very characteristic distribution patterns of flash pyrolysis products (e.g., alkan-9- and -10-ones, alkadienes) of the Ribesalbes kerogen revealed that it is predominantly composed of fossilized organic matter of the freshwater alga Botryococcus braunii. These two findings demonstrate that sulfurization of organic matter may also occur in lacustrine sediments provided that sulfate is supplied by external sources. Data on the third kerogen sample (Cerdanya) suggest that the freshwater alga Pediastrum may contain a (partly) aromatic biomacromolecule that is selectively preserved upon diagenesis. These findings testify to the large variability in palaeodepositional conditions in lacutrine environments. A comparison of the biomarker composition of the extract of the Ribesalbes oil shale with the kerogen composition indicate that biomarkers often cannot be used to assess the major sources of organic matter in such settings. A similar conclusion can be drawn from a comparison of literature data concerning the Messel Oil Shale. 75 refs., 18 figs., 7 tabs.

Late Noachian Icy Highlands climate model: Exploring the possibility of transient melting and fluvial/lacustrine activity through peak annual and seasonal temperatures

Science.gov (United States)

Palumbo, Ashley M.; Head, James W.; Wordsworth, Robin D.

2018-01-01

The nature of the Late Noachian climate of Mars remains one of the outstanding questions in the study of the evolution of martian geology and climate. Despite abundant evidence for flowing water (valley networks and open/closed basin lakes), climate models have had difficulties reproducing mean annual surface temperatures (MAT) > 273 K in order to generate the ;warm and wet; climate conditions presumed to be necessary to explain the observed fluvial and lacustrine features. Here, we consider a ;cold and icy; climate scenario, characterized by MAT ∼225 K and snow and ice distributed in the southern highlands, and ask: Does the formation of the fluvial and lacustrine features require continuous ;warm and wet; conditions, or could seasonal temperature variation in a ;cold and icy; climate produce sufficient summertime ice melting and surface runoff to account for the observed features? To address this question, we employ the 3D Laboratoire de Météorologie Dynamique global climate model (LMD GCM) for early Mars and (1) analyze peak annual temperature (PAT) maps to determine where on Mars temperatures exceed freezing in the summer season, (2) produce temperature time series at three valley network systems and compare the duration of the time during which temperatures exceed freezing with seasonal temperature variations in the Antarctic McMurdo Dry Valleys (MDV) where similar fluvial and lacustrine features are observed, and (3) perform a positive-degree-day analysis to determine the annual volume of meltwater produced through this mechanism, estimate the necessary duration that this process must repeat to produce sufficient meltwater for valley network formation, and estimate whether runoff rates predicted by this mechanism are comparable to those required to form the observed geomorphology of the valley networks. When considering an ambient CO2 atmosphere, characterized by MAT ∼225 K, we find that: (1) PAT can exceed the melting point of water (>273 K) in

Mapping sediment–landform assemblages to constrain lacustrine sedimentation in a glacier-fed lake catchment in northwest Spitsbergen

OpenAIRE

Bilt, Willem van der; Balascio, Nicholas L.; Bakke, Jostein

2015-01-01

Changes in the deposition of fine-grained rock-flour in glacier-fed lakes reflect glacier variability. This meltwater-driven signal is, however, often overprinted by other processes. To constrain the signature of lacustrine sedimentation, we mapped the catchment of glacier-fed Lake Hajeren in northwest Spitsbergen, identifying sediment sources and linking them to surface processes. To this end, we employed a combined approach of aerial image interpretation and field mapping. Our map comprises...

Biostratigraphical correlation of a new interglacial lacustrine deposit from Lind, western Jutland, Denmark

DEFF Research Database (Denmark)

Odgaard, Bent Vad; Krohn, Charlotte Fog; Kronborg, Christian

2008-01-01

and animal macrofossils and two cores were secured from the central part of the basin where the lacustrine deposits have a thickness of about 15 m. The stratigraphy of the deposit can be subdivided into unit A: a lake marl (4 m) superimposed by 3 metres of diatomite and sealed by a thin diamicton. On top...... of unit A follows unit B: 4 metres of gyttja, calcareous at the basal part and sealed by 40 cm of clay. Finally unit C on top of unit B is represented by 1.5 metres of gyttja. The pollen record of unit A can be correlated to the classical Danish record from the nearby Harreskov site (Andersen 1965...

Palaeoenvironments during MIS 3 and MIS 2 inferred from lacustrine intercalations in the loess-palaeosol sequence at Bobingen (southern Germany)

Science.gov (United States)

Mayr, Christoph; Matzke-Karasz, Renate; Stojakowits, Philipp; Lowick, Sally E.; Zolitschka, Bernd; Heigl, Tanja; Mollath, Richard; Theuerkauf, Marian; Weckend, Marc-Oliver; Bäumler, Rupert; Gregor, Hans-Joachim

2017-12-01

Recently exposed loess-palaeosol sequences in the northern Alpine foreland close to Bobingen (southern Germany) were investigated with a multi-proxy approach combining isotopic, geochemical, lithological, and micropalaeontological methods. Luminescence ages date the sections into the Middle and Upper Würmian periods corresponding to Marine Isotope Stages 3 and 2. A gleyic soil horizon at the base was dated to 45 ka and provided a palynoflora dominated by Poaceae, Cyperaceae, and Pinus, as well as frequent aquatic taxa. Lacustrine conditions prevailed after the gley formation until 30 ka, providing a comparatively diverse lacustrine fauna dominated by aquatic gastropods and the ostracod species Candona candida. At the transition to the Upper Würm, climatic conditions became harsh, indicated by accelerated deposition of more coarse-grained loess, organic geochemical indicators, and scarceness of biotic remains. Two tundra-gley horizons in the Upper Würm point to short phases of climatic amelioration with higher humidity also evidenced by reoccurrence of ostracod and aquatic gastropod remains. We propose that these climatic ameliorations were coincident with the Greenland interstadials 4 and 2.

Hydrothermal alteration and diagenesis of terrestrial lacustrine pillow basalts: Coordination of hyperspectral imaging with laboratory measurements

Science.gov (United States)

Greenberger, Rebecca N.; Mustard, John F.; Cloutis, Edward A.; Mann, Paul; Wilson, Janette H.; Flemming, Roberta L.; Robertson, Kevin M.; Salvatore, Mark R.; Edwards, Christopher S.

2015-12-01

We investigate an outcrop of ∼187 Ma lacustrine pillow basalts of the Talcott Formation exposed in Meriden, Connecticut, USA, focusing on coordinated analyses of one pillow lava to characterize the aqueous history of these basalts in the Hartford Basin. This work uses a suite of multidisciplinary measurements, including hyperspectral imaging, other spectroscopic techniques, and chemical and mineralogical analyses, from the microscopic scale up to the scale of an outcrop. The phases identified in the sample are albite, large iron oxides, and titanite throughout; calcite in vesicles; calcic clinopyroxene, aegirine, and Fe/Mg-bearing clay in the rind; and fine-grained hematite and pyroxenes in the interior. Using imaging spectroscopy, the chemistry and mineralogy results extend to the hand sample and larger outcrop. From all of the analyses, we suggest that the pillow basalts were altered initially after emplacement, either by heated lake water or magmatic fluids, at temperatures of at least 400-600 °C, and the calcic clinopyroxenes and aegirine identified in the rind are a preserved record of that alteration. As the hydrothermal system cooled to slightly lower temperatures, clays formed in the rind, and, during this alteration, the sample oxidized to form hematite in the matrix of the interior and Fe3+ in the pyroxenes in the rind. During the waning stages of the hydrothermal system, calcite precipitated in vesicles within the rind. Later, diagenetic processes albitized the sample, with albite replacing plagioclase, lining vesicles, and accreting onto the exterior of the sample. This albitization or Na-metasomatism occurred when the lake within the Hartford Basin evaporated during a drier past climatic era, resulting in Na-rich brines. As Ca-rich plagioclase altered to albite, Ca was released into solution, eventually precipitating as calcite in previously-unfilled vesicles, dominantly in the interior of the pillow. Coordinated analyses of this sample permit

A geochemical record of the link between chemical weathering and the East Asian summer monsoon during the late Holocene preserved in lacustrine sediments from Poyang Lake, central China

Science.gov (United States)

Huang, Chao; Wei, Gangjian; Li, Wuxian; Liu, Ying

2018-04-01

This paper presents relatively high-resolution geochemical records spanning the past 4000 cal yr BP obtained from the lacustrine sediments of Poyang Lake in central China. The variations in the intensity of the East Asian summer monsoon (EASM) are traced using the K/Na, Ti/Na, Al/K, kaolinite/illite and clay/feldspar ratios, together with the chemical index of alteration (CIA), as indicators of chemical weathering. During the last 4000 years, the proxy records of chemical weathering from Poyang Lake exhibit an overall enhanced trend, consistent with regional hydrological changes in previous independent records. Further comparisons and analyses demonstrate that regional moisture variations in central China is inversely correlated with the EASM intensity, with weak EASM generating high precipitation in central China. Our data reveal three intervals of dramatically dry climatic conditions (i.e., ca. 4000-3200 cal yr BP, ca. 2800-2400 cal yr BP, and ca. 500-200 cal yr BP). A period of weak chemical weathering, related to cold and dry climatic conditions, occurred during the Little Ice Age (LIA), whereas more intense chemical weathering, reflecting warm and humid climatic conditions, was recorded during the Medieval Warm Period (MWP). Besides, an intensification of chemical weathering in Poyang Lake during the late Holocene agrees well with strong ENSO activity, suggesting that moisture variations in central China may be predominantly driven by ENSO variability.

Sources and proxy potential of long chain alkyl diols in lacustrine environments

Science.gov (United States)

Rampen, Sebastiaan W.; Datema, Mariska; Rodrigo-Gámiz, Marta; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.

2014-11-01

Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD) composition of cultures of ten eustigmatophyte species, with three species from different families grown at various temperatures, to identify the effect of species composition and growth temperature on the LCD distribution. The results were compared with the LCD distribution of sixty-two lake surface sediments, and with previously reported LCD distributions from marine environments. The different families within the Eustigmatophyceae show distinct LCD patterns, with the freshwater family Eustigmataceae most closely resembling LCD distributions in both marine and lake environments. Unlike the other two eustigmatophyte families analyzed (Monodopsidaceae and Goniochloridaceae), C28 and C30 1,13-alkyl diols and C30 and C32 1,15-alkyl diols are all relatively abundant in the family Eustigmataceae, while the mono-unsaturated C32 1,15-alkyl diol was below detection limit. In contrast to the marine environment, LCD distributions in lakes did not show a clear relationship with temperature. The Long chain Diol Index (LDI), a proxy previously proposed for sea surface temperature reconstruction, showed a relatively weak correlation (R2 = 0.33) with mean annual air temperature used as an approximation for annual mean surface temperature of the lakes. A much-improved correlation (R2 = 0.74, p-value cultures of the family Eustigmataceae, suggesting that algae belonging to this family have an important role as a source for LCDs in lacustrine environments, or, alternatively, that the main sources of LCDs are similarly affected by temperature as the Eustigmataceae. The results suggest that LCDs may have the potential to be applicable as a palaeotemperature proxy for lacustrine environments

The lacustrine sediment record of Oberwinkler Maar (Eifel, Germany): Chironomid and macro-remain-based inferences of environmental changes during Oxygen Isotope Stage 3

NARCIS (Netherlands)

Engels, S.; Bohncke, S.J.P.; Heiri, O.; Schaber, K.; Sirocko, F.

2008-01-01

The lacustrine record of Oberwinkler Maar (Eifel, Germany) is the northernmost continuous record documenting the Weichselian Pleniglacial in central Europe - a period characterized by multiple abrupt climate oscillations known as the Dansgaard/Oeschger cycles. Here, the results of a high-resolution

Morphometric variation between two morphotypes within the Astyanax Baird and Girard, 1854 (Actinopterygii: Characidae) genus, from a Mexican tropical lake.

Science.gov (United States)

Ornelas-García, Claudia P; Bastir, Markus; Doadrio, Ignacio

2014-07-01

Phenotypic variation is important for evolutionary processes because it can allow local adaptation, promote genetic segregation, and ultimately give rise to speciation. Lacustrine systems provide a unique opportunity to study the mechanisms by which sister species can co-occur by means of ecological segregation. The fish genus Astyanax is characterized by high levels of phenotypic variability, providing an excellent model for the study of local specialization. Here, we analyze the morphological specializations through geometric morphometrics of two sympatric species described as different genera: Bramocharax caballeroi endemic to Lake Catemaco, and the widely distributed Astyanax aeneus. Additionally, we assess the correlation between phenotypic and genetic structure, and the phylogenetic signal of morphological variation. We examined body size and shape variation in 196 individuals and analyzed mitochondrial cytochrome b sequences in 298 individuals. Our results confirm the striking morphological divergence among the sympatric characids. Differences between them were mainly found in the body depth and profile and orientation of the head, where B. caballeroi in contrast with the A. aeneus, presented a fusiform body and an upward mouth. Moreover, different growth trajectories were observed among morphotypes, suggesting that a heterochronic process could be involved in the diversification of our study system. Morphological differences did not correspond with the molecular differentiation, suggesting high levels of homoplasy among the lineages of B. caballeroi morphs. © 2014 Wiley Periodicals, Inc.

Depositional system of the Bayangobi formation, lower cretaceous and its control over in-situ leachable sandstone-type uranium deposits in Chagandelesu area, Inner Mongolia

International Nuclear Information System (INIS)

Zhang Wanliang

2002-01-01

Chagandelesu area is situated in the eastern part of Bayangobi basin, Inner Mongolia. In the Early Cretaceous, a detrital rock series (Bayangobi Formation) with a thickness of about 1000 m was formed within a down-faulted basin under the extensional tectonic regime. The Bayangobi Formation is the prospecting target for interlayer oxidation zone sandstone-type uranium deposits, and is divided into three lithologic members: the lower member-- proluvial (alluvial), subaqueous fan or fan-delta facies sediments; the middle member-shallow lacustrine-semi-deep lacustrine-deep lacustrine facies sediments; the upper member-littoral shallow lacustrine or delta facies sediments. The facies order of Bayangobi Formation represents the evolution process of basin water from the shallow (early period) to the deep (middle period) then again to the shallow (late period) level. The Bayangobi Formation composed of a third sequence order reflects respectively a lowstand system tract (LST), a transgressive system tract (TST) and a highstand system tract (HST). The author also makes an analysis on physical properties of psammites of Bayangobi Formation, and proposes that psammites of delta and littoral shallow lacustrine facies are favourable for the formation of interlayer oxidation zone sandstone-type uranium deposits

Soft-sediment deformation structures in cores from lacustrine slurry deposits of the Late Triassic Yanchang Fm. (central China

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Yang Renchao

2016-09-01

Full Text Available The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China.

Climatic and lacustrine morphometric controls of diatom paleoproductivity in a tropical Andean lake

Science.gov (United States)

Bao, R.; Hernández, A.; Sáez, A.; Giralt, S.; Prego, R.; Pueyo, J. J.; Moreno, A.; Valero-Garcés, B. L.

2015-12-01

The coupling of lake dynamics with catchment biogeochemistry is considered the key element controlling primary production in mountain lakes at time scales of a few decades to millennia, yet little is known on the impacts of the morphometry of lakes throughout their ontogeny. As Lake Chungará (Central Andean Altiplano, northern Chile) experienced long-term lake-level fluctuations that strongly modified its area:volume ratio, it is an ideal system for exploring the relative roles that long-term climatic shifts and lake morphometry play on biosiliceous lacustrine productivity. In this paper, we review previous data on the percent contents of total organic carbon, total inorganic carbon, total nitrogen, total biogenic silica, isotopic composition of organic matter, carbonates, and diatom frustules, as well as data on the abundance of the chlorophycean Botryococcus braunii in this lake for the period 12,400-1300 cal yr BP. We also include new data on organic carbon and biogenic silica mass accumulation rates and the diatom assemblage composition of an offshore core dated using 14C and U/Th. Biosiliceous productivity in Lake Chungará was influenced by shifts in allochthonous nutrient inputs related to variability in precipitation. Humid phases dated at approx. 12,400 to 10,000 and 9600 to 7400 cal yr BP coincide with periods of elevated productivity, whereas decreases in productivity were recorded during arid phases dated at approx. 10,000 to 9600 and 7400 to 3550 cal yr BP (Andean mid-Holocene Aridity Period). However, morphometry-related in-lake controls led to a lack of a linear response of productivity to precipitation variability. During the late Glacial to early Holocene, lowstands facilitated complete water column mixing, prompting episodic massive blooms of a large centric diatom, Cyclostephanos cf. andinus. Thus, moderate productivity could be maintained, regardless of aridity, by this phenomenon of morphometric eutrophy during the early history of the lake

Climatic instability before the Miocene Climatic Optimum reflected in a Central European lacustrine record from the Most Basin in the Czech Republic

Czech Academy of Sciences Publication Activity Database

Matys Grygar, Tomáš; Hošek, Michal; Mach, K.; Schnabl, Petr; Martinez, M.

2017-01-01

Roč. 485, NOV (2017), s. 930-945 ISSN 0031-0182 R&D Projects: GA ČR(CZ) GA16-00800S Institutional support: RVO:61388980 ; RVO:67985831 Keywords : Chemostratigraphy * Cyclostratigraphy * Lacustrine * Magnetostratigraphy * MCO * Siliciclastic Subject RIV: DD - Geochemistry; DB - Geology ; Mineralogy (GLU-S) OBOR OECD: Geology Impact factor: 2.578, year: 2016

THE AZYGOS VENOUS SYSTEM AND ITS ANATOMICAL VARIATIONS

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Madiki Sudhakara Rao

2016-06-01

Full Text Available AIMS AND OBJECTIVES Azygos veins are important cavocaval and portacaval junctions, which form a collateral circulation in caval vein occlusion and in portal hypertension, cirrhosis of liver. The unpaired azygos venous system consists of azygos vein, hemiazygos vein and accessory azygos vein. This system of veins, along with its mediastinal, bronchial and oesophageal tributaries drains most of the body wall of trunk, namely posterior abdominal and thoracic wall. Anatomical variations of this unpaired azygos venous system are clinically important. AIMS To study and report the occurrence of anatomical variations of the unpaired azygos venous system in the region of East Godavari District, Andhra Pradesh (India. METHODS The present study was carried out in the Department of Anatomy, KIMS & RF, Amalapuram and G.S.L. Medical College, Rajahmundry over a period of 2 years. The present study was conducted on 60 cadavers (irrespective of age and sex. The entire course of the azygos venous system in these 60 cadavers was carefully observed and documented. RESULTS Anatomical variations were present in 16.66% of cases, out of which three distinct types were identified. 6.6% exhibited two separate azygos venous systems with no communications, 5% with communication between the left brachiocephalic vein and the azygos vein and 5% presence of post-aortic venous channels. CONCLUSION Variations of azygos venous system may be wrongly dubbed as aneurysm, lymphadenopathy or other abnormalities while reporting a CT scan of mediastinum. Venous anomalies are also detected only during surgery. The most troublesome intraoperative hazard is haemorrhage, which is mainly of venous origin. To avoid such situations is to have an awareness and knowledge of the expected venous anomalies.

Chapter F: Preliminary Bibliography of Lacustrine Diatomite Deposits in the Western United States and Related Topics

Science.gov (United States)

Bolm, Karen S.; Wallace, Alan R.; Moyle, Phillip R.; Bliss, James D.; Orris, Greta J.

2003-01-01

Introduction As part of the assessment of lacustrine diatomite resources in the Western United States (fig. 1), U.S. Geological Survey (USGS) project members conducted a review of literature relating to the formation, location, and nature of deposits in the study area. This preliminary bibliography consists of selected publications to identify, locate, and describe the deposits to be studied, to characterize common geologic factors about the deposits, and to better understand the factors that control their formation, preservation, or destruction. The bibliography also serves as a resource for other workers to research the topic. References included in the preliminary bibliography were gathered by searching existing bibliographic data bases and library collections. Project researchers also contributed references that they found during the course of their work. This bibliography should be considered a working document that will grow as research and literature searches continue. Clearly, many significant publications may be missing from this preliminary list; therefore, USGS staff members intend to issue a revised bibliography as project work progresses. To assure completeness, input from other researchers and industry is welcome. Although the focus of this bibliography is lacustrine diatomite deposits of the Western United States, additional references that provide a foundation of knowledge for the study of diatomites, diatoms, and diatom-related processes (ecology, geology, geochemistry) and for the uses and behavior of diatomite have also been included. An index of keywords has been added to this bibliography, designed to help the user locate reports by topic or by geographic location. The letter 'A' following a number indicates that the report referenced is an abstract.

Geochemical characteristics of Holocene laminated sapropel (unit II) and underlying lacustrine unit III in the Black Sea

Science.gov (United States)

Dean, Walter E.; Arthur, Michael A.

2011-01-01

eg 1 of the 1988 R/V Knorr expeditions to the Black Sea recovered 90 gravity and box cores. The longest recovery by gravity cores was about 3 meters, with an average of about 2.5 meters, recovering all of the Holocene and upper Pleistocene sections in the Black Sea. During the latest Pleistocene glaciation, sea level dropped below the 35-meters-deep Bosporus outlet sill of the Black Sea. Therefore throughout most of its history the Black Sea was a lake, and most of its sediments are lacustrine. The oldest sediments recovered (older than 8,000 calendar years) consist of massive to coarsely banded lacustrine calcareous clay designated as lithologic Unit III, generally containing less than 1 percent organic carbon (OC). The base of overlying Unit II marks the first incursion of Mediterranean seawater into the Black Sea, and the onset of bottom-water anoxia about 7,900 calendar years. Unit II contains as much as 15 percent OC in cores from the deepest part of the Black Sea (2,200 meters). The calcium carbonate (CaCO3) remains of the coccolith Emiliania huxleyi form the distinctive white laminae of overlying Unit I. The composition of Unit III and Unit II sediments are quite different, reflecting different terrigenous clastic sources and increased contributions from hydrogenous and biogenic components in anoxic Unit II sapropel. In Unit II, positive covariance between OC and three trace elements commonly concentrated in OC-rich sediments where sulfate reduction has occurred (molybdenum, nickel, and vanadium) and a nutrient (phosphorus) suggest a large marine source for these elements although nickel and vanadium also have a large terrigenous clastic source. The marine sources may be biogenic or hydrogenous. A large biogenic source is also suggested for copper and cobalt. Because abundant pyrite forms in the water column and sediments of the Black Sea, we expected to find a large hydrogenous iron component, but a strong covariance of iron with aluminum suggests that the

Lacustrine basin evolution and coal accumulation of the Middle Jurassic in the Saishiteng coalfield, northern Qaidam Basin, China

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Meng Li

2016-07-01

Full Text Available Based on an extensive borehole survey of the Middle Jurassic coal-bearing sequences in the Saishiteng coalfield, northern Qaidam Basin (NQB, a total of 20 rock types and 5 sedimentary facies were identified, including braided river, meandering river, braided delta, meandering river delta, and lacustrine facies. The distribution of rock types and sedimentary facies contributed to the reconstruction of three periods' sedimentary facies maps of the Middle Jurassic in the Saishiteng coalfield, namely, the Dameigou age, the early Shimengou age and the late Shimengou age. That also provided the basis for the development of a three-stage depositional model of the Middle Jurassic in the NQB, indicating the lacustrine basin of the NQB in the Dameigou age and early Shimengou age were corresponding to an overfill basin, and that in the late Shimengou age was related to a balanced-fill basin. The analysis of the stability and structure of coal seams based on sedimentary facies maps showed that the preferred coal-forming facies in the Saishiteng coalfield were inter-delta bay and interdistributary bay of lower delta plain in the Dameigou age. In particular, the swamps that developed on the subaqueous palaeohigh favored the development of thick coal seams. Thus, minable coal seams may also be found along the Pingtai palaeohigh in the western part of the Saishiteng coalfield.

Variational discretization of the nonequilibrium thermodynamics of simple systems

Science.gov (United States)

Gay-Balmaz, François; Yoshimura, Hiroaki

2018-04-01

In this paper, we develop variational integrators for the nonequilibrium thermodynamics of simple closed systems. These integrators are obtained by a discretization of the Lagrangian variational formulation of nonequilibrium thermodynamics developed in (Gay-Balmaz and Yoshimura 2017a J. Geom. Phys. part I 111 169–93 Gay-Balmaz and Yoshimura 2017b J. Geom. Phys. part II 111 194–212) and thus extend the variational integrators of Lagrangian mechanics, to include irreversible processes. In the continuous setting, we derive the structure preserving property of the flow of such systems. This property is an extension of the symplectic property of the flow of the Euler–Lagrange equations. In the discrete setting, we show that the discrete flow solution of our numerical scheme verifies a discrete version of this property. We also present the regularity conditions which ensure the existence of the discrete flow. We finally illustrate our discrete variational schemes with the implementation of an example of a simple and closed system.

Influence of Design Variations on Systems Performance

Science.gov (United States)

Tumer, Irem Y.; Stone, Robert B.; Huff, Edward M.; Norvig, Peter (Technical Monitor)

2000-01-01

High-risk aerospace components have to meet very stringent quality, performance, and safety requirements. Any source of variation is a concern, as it may result in scrap or rework. poor performance, and potentially unsafe flying conditions. The sources of variation during product development, including design, manufacturing, and assembly, and during operation are shown. Sources of static and dynamic variation during development need to be detected accurately in order to prevent failure when the components are placed in operation. The Systems' Health and Safety (SHAS) research at the NASA Ames Research Center addresses the problem of detecting and evaluating the statistical variation in helicopter transmissions. In this work, we focus on the variations caused by design, manufacturing, and assembly of these components, prior to being placed in operation (DMV). In particular, we aim to understand and represent the failure and variation information, and their correlation to performance and safety and feed this information back into the development cycle at an early stage. The feedback of such critical information will assure the development of more reliable components with less rework and scrap. Variations during design and manufacturing are a common source of concern in the development and production of such components. Accounting for these variations, especially those that have the potential to affect performance, is accomplished in a variety ways, including Taguchi methods, FMEA, quality control, statistical process control, and variation risk management. In this work, we start with the assumption that any of these variations can be represented mathematically, and accounted for by using analytical tools incorporating these mathematical representations. In this paper, we concentrate on variations that are introduced during design. Variations introduced during manufacturing are investigated in parallel work.

The Index to Marine and Lacustrine Geological Samples: Improving Sample Accessibility and Enabling Current and Future Research

Science.gov (United States)

Moore, C.

2011-12-01

The Index to Marine and Lacustrine Geological Samples is a community designed and maintained resource enabling researchers to locate and request sea floor and lakebed geologic samples archived by partner institutions. Conceived in the dawn of the digital age by representatives from U.S. academic and government marine core repositories and the NOAA National Geophysical Data Center (NGDC) at a 1977 meeting convened by the National Science Foundation (NSF), the Index is based on core concepts of community oversight, common vocabularies, consistent metadata and a shared interface. Form and content of underlying vocabularies and metadata continue to evolve according to the needs of the community, as do supporting technologies and access methodologies. The Curators Consortium, now international in scope, meets at partner institutions biennially to share ideas and discuss best practices. NGDC serves the group by providing database access and maintenance, a list server, digitizing support and long-term archival of sample metadata, data and imagery. Over three decades, participating curators have performed the herculean task of creating and contributing metadata for over 195,000 sea floor and lakebed cores, grabs, and dredges archived in their collections. Some partners use the Index for primary web access to their collections while others use it to increase exposure of more in-depth institutional systems. The Index is currently a geospatially-enabled relational database, publicly accessible via Web Feature and Web Map Services, and text- and ArcGIS map-based web interfaces. To provide as much knowledge as possible about each sample, the Index includes curatorial contact information and links to related data, information and images; 1) at participating institutions, 2) in the NGDC archive, and 3) at sites such as the Rolling Deck to Repository (R2R) and the System for Earth Sample Registration (SESAR). Over 34,000 International GeoSample Numbers (IGSNs) linking to SESAR are

Types of soft-sediment deformation structures in a lacustrine Ploužnice member (Stephanian, Gzhelian, Pennsylvanian, Bohemian Massif), their timing, and possible trigger mechanism

Czech Academy of Sciences Publication Activity Database

Stárková, M.; Martínek, K.; Mikuláš, Radek; Rosenau, N.

2015-01-01

Roč. 104, č. 5 (2015), s. 1277-1298 ISSN 1437-3254 Institutional support: RVO:67985831 Keywords : soft-sediment deformation structures * bioturbation * early diagenetic carbonate * lacustrine facies * Bohemian Massif * Stephanian C * Krkonoše Piedmont Basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.133, year: 2015

Branched GDGTs in Lacustrine Environments: Tracing Allochthonous and Autochthonous Sources Using Compound-Specific Stable Carbon Isotope Analysis

Science.gov (United States)

Weber, Y.; S Sinninghe Damsté, J.; Lehmann, M. F.; Niemann, H.; Schubert, C. J.

2015-12-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are ubiquitous in soils and peat, as well as in sediments of lakes, rivers and coastal marine environments. It has been found that the distribution of brGDGTs changes systematically with ambient temperature and pH, attesting to their potential as proxy indicators for paleoclimatic reconstruction. In lacustrine sedimentary archives, brGDGTs can originate from two sources: (1) allochthonous soil organic matter and (2) autochthonous brGDGTs produced within the lake system, both of which display fairly distinct temperature-brGDGT relationships. Until now, disentangling the relative contribution of these sources was impossible, complicating the use of brGDGTs for quantitative paleotemperature reconstructions. BrGDGTs in soils display a narrow range with respect to their stable carbon isotope composition (δ13C), generally between -27 and -30 ‰, whereas we recently found contrasting δ13C values as low as -43 ‰ to -46 ‰ for brGDGTs in sediments of a small Alpine lake. To trace the origin of this distinct isotope signal, we determined the 13C content of brGDGTs in suspended particulate matter (SPM) from the water column of Lake Lugano (Switzerland). The δ13C of SPM-derived brGDGTs decreased systematically from -34 ‰ in the mixolimnion to -41 ‰ in the anoxic monimolimnion of Lake Lugano, providing evidence for aquatic in situ production of 13C-depleted brGDGT. In order to study whether the negative δ13C offset of water column- vs. soil-derived brGDGTs may serve as an indicator for lacustrine brGDGT production, we also analyzed surface sediments from 36 lakes across the Alpine Region. In most (~85 %) of the studied lake sediments, the δ13C of brGDGTs ranged between -34 ‰ and -45 ‰, indicating predominance or a substantial contribution of aquatically produced brGDGTs. However, in some lakes (~15 %) δ13C values between -27 ‰ and -30 ‰ suggest a mainly

Effects of Aeration, Vegetation, and Iron Input on Total P Removal in a Lacustrine Wetland Receiving Agricultural Drainage

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Yuanchun Zou

2018-01-01

Full Text Available Utilizing natural wetlands to remove phosphorus (P from agricultural drainage is a feasible approach of protecting receiving waterways from eutrophication. However, few studies have been carried out about how these wetlands, which act as buffer zones of pollutant sinks, can be operated to achieve optimal pollutant removal and cost efficiency. In this study, cores of sediments and water were collected from a lacustrine wetland of Lake Xiaoxingkai region in Northeastern China, to produce a number of lab-scale wetland columns. Ex situ experiments, in a controlled environment, were conducted to study the effects of aeration, vegetation, and iron (Fe input on the removal of total P (TP and values of dissolved oxygen (DO and pH of the water in these columns. The results demonstrated the links between Fe, P and DO levels. The planting of Glyceria spiculosa in the wetland columns was found to increase DO and pH values, whereas the Fe:P ratio was found to inversely correlate to the pH values. The TP removal was the highest in aerobic and planted columns. The pattern of temporal variation of TP removals matched first-order exponential growth model, except for under aerobic condition and with Fe:P ratio of 10:1. It was concluded that Fe introduced into a wetland by either surface runoff or agricultural drainage is beneficial for TP removal from the overlying water, especially during the growth season of wetland vegetation.

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

KAUST Repository

Hubert-Ferrari, Auré lia; El-Ouahabi, Meriam; Garcia-Moreno, David; Avsar, Ulas; Altınok, Sevgi; Schmidt, Sabine; Fagel, Nathalie; Ç ağatay, Namık

2017-01-01

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.

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.

Organic compositions of lacustrine source rocks in Jiyang super-depression and its implication to petroleum geology

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The compositions of organic matter in four immature source rocks from Tertiary strata of Jiyang super-depression, the most typical continental rift subsidence basin in East China, have been studied by different extracting methods with CHCl3, MAC and CS2/NMP, respectively. The results suggest that there are great differences among the chemical compositions of organic matter in the source rocks derived from different depositional environments. About 79% of all the organic matter exists by non- covalent bond in the Es4 source rocks which were deposited under the saline lacustrine, indicating that its organic matter is not the real kerogen, but mainly composed of soluble organic matter which is easy to generate hydrocarbon at lower temperature. This is why the immature oils were derived from Es4 source rocks in Dongying depression. In contrast, around 60% of organic matter exists by covalent bond in Es3 source rocks which were deposited under the deep brackish-fresh lacustrine, showing that Es3 source rocks are mainly composed of kerogen producing mature hydrocarbon at higher temperature. The thermal simulation experiments, upon the remaining solid source rocks which were sequentially extracted by the three solvents, have been carried out. The chloroform extracts from the simulation product have been compared with the other three solvent extracts gained at room temperature. It is obvious that remarkable odd/even predominance (OEP) is mainly the characteristic of soluble organic matter; phytane mostly exists in the soluble organic matter by means of non-covalent bonds and characteristics of soluble organic matter are similar to these in immature oils produced in Jiyang super-depression.

Pleistocene lake outburst floods and fan formation along the eastern Sierra Nevada, California: implications for the interpretation of intermontane lacustrine records

Science.gov (United States)

Benn, Douglas I.; Owen, Lewis A.; Finkel, Robert C.; Clemmens, Samuel

2006-11-01

Variations in the rock flour fraction in intermontane lacustrine sediments have the potential to provide more complete records of glacier fluctuations than moraine sequences, which are subject to erosional censoring. Construction of glacial chronologies from such records relies on the assumption that rock flour concentration is a simple function of glacier extent. However, other factors may influence the delivery of glacigenic sediments to intermontane lakes, including paraglacial adjustment of slope and fluvial systems to deglaciation, variations in precipitation and snowmelt, and lake outburst floods. We have investigated the processes and chronology of sediment transport on the Tuttle and Lone Pine alluvial fans in the eastern Sierra Nevada, California, USA, to elucidate the links between former glacier systems located upstream and the long sedimentary record from Owens Lake located downstream. Aggradation of both fans reflects sedimentation by three contrasting process regimes: (1) high magnitude, catastrophic floods, (2) fluvial or glacifluvial river systems, and (3) debris flows and other slope processes. Flood deposits are represented by multiple boulder beds exposed in section, and extensive networks of large palaeochannels and boulder deposits on both fan surfaces. Palaeohydrological analysis implies peak discharges in the order of 10 3-10 4 m 3 s -1, most probably as the result of catastrophic drainage of ice-, moraine-, and landslide-dammed lakes. Cosmogenic radionuclide surface exposure dating shows that at least three flood events are represented on each fan, at 9-13, 16-18 and 32-44 ka (Tuttle Fan); and at ˜23-32, ˜80-86 ka, and a poorly constrained older event (Lone Pine Fan). Gravels and sands exposed in both fans represent fluvial and/or glacifluvial sediment transport from the Sierra Nevada into Owens Valley, and show that river systems incised and reworked older sediment stored in the fans. We argue that millennial-scale peaks in rock flour

Earthquake-induced soft-sediment deformation structures in Late Pleistocene lacustrine deposits of Issyk-Kul lake (Kyrgyzstan)

Science.gov (United States)

Gladkov, A. S.; Lobova, E. U.; Deev, E. V.; Korzhenkov, A. M.; Mazeika, J. V.; Abdieva, S. V.; Rogozhin, E. A.; Rodkin, M. V.; Fortuna, A. B.; Charimov, T. A.; Yudakhin, A. S.

2016-10-01

This paper discusses the composition and distribution of soft-sediment deformation structures induced by liquefaction in Late Pleistocene lacustrine terrace deposits on the southern shore of Issyk-Kul Lake in the northern Tien Shan mountains of Kyrgyzstan. The section contains seven deformed beds grouped in two intervals. Five deformed beds in the upper interval contain load structures (load casts and flame structures), convolute lamination, ball-and-pillow structures, folds and slumps. Deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope. The dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the Late Pleistocene.

Prioritizing Wetlands for Waterbirds in a Boom and Bust System: Waterbird Refugia and Breeding in the Murray-Darling Basin.

Science.gov (United States)

Bino, Gilad; Kingsford, Richard T; Porter, John

2015-01-01

Dryland rivers have considerable flow variability, producing complex ecosystems, processes, and communities of organisms that vary over space and time. They are also among the more vulnerable of the world's ecosystems. A key strategy for conservation of dryland rivers is identifying and maintaining key sites for biodiversity conservation, particularly protecting the quantity and quality of flow and flooding regimes. Extreme variability considerably challenges freshwater conservation planning. We systematically prioritised wetlands for waterbirds (simultaneously for 52 species), across about 13.5% of the Murray-Darling Basin (1,061,469 km2), using a 30-year record of systematic aerial surveys of waterbird populations. Nine key wetlands in this area, primarily lakes, floodplains, and swamps, consistently contributed to a representation target (80%) of total abundances of all 52 waterbird species. The long temporal span of our data included dramatic availability (i.e., booms) and scarcity (i.e., busts) of water, providing a unique opportunity to test prioritisation at extremes of variation. These extremes represented periods when waterbirds were breeding or concentrating on refugia, varying wetland prioritisation. In dry years, important wetlands for waterbirds were riverine and lacustrine (12 wetlands) but this changed in wet years to lacustrine and palustrine (8 wetlands). Such variation in ecosystem condition substantially changes the relative importance of individual wetlands for waterbirds during boom and bust phases. Incorporating this variability is necessary for effective conservation of Murray-Darling Basin waterbirds, with considerable generality for other similarly variable systems around the world.

Prioritizing Wetlands for Waterbirds in a Boom and Bust System: Waterbird Refugia and Breeding in the Murray-Darling Basin.

Directory of Open Access Journals (Sweden)

Gilad Bino

Full Text Available Dryland rivers have considerable flow variability, producing complex ecosystems, processes, and communities of organisms that vary over space and time. They are also among the more vulnerable of the world's ecosystems. A key strategy for conservation of dryland rivers is identifying and maintaining key sites for biodiversity conservation, particularly protecting the quantity and quality of flow and flooding regimes. Extreme variability considerably challenges freshwater conservation planning. We systematically prioritised wetlands for waterbirds (simultaneously for 52 species, across about 13.5% of the Murray-Darling Basin (1,061,469 km2, using a 30-year record of systematic aerial surveys of waterbird populations. Nine key wetlands in this area, primarily lakes, floodplains, and swamps, consistently contributed to a representation target (80% of total abundances of all 52 waterbird species. The long temporal span of our data included dramatic availability (i.e., booms and scarcity (i.e., busts of water, providing a unique opportunity to test prioritisation at extremes of variation. These extremes represented periods when waterbirds were breeding or concentrating on refugia, varying wetland prioritisation. In dry years, important wetlands for waterbirds were riverine and lacustrine (12 wetlands but this changed in wet years to lacustrine and palustrine (8 wetlands. Such variation in ecosystem condition substantially changes the relative importance of individual wetlands for waterbirds during boom and bust phases. Incorporating this variability is necessary for effective conservation of Murray-Darling Basin waterbirds, with considerable generality for other similarly variable systems around the world.

Nonterminals, homomorphisms and codings in different variations of OL-systems. II. Nondeterministic systems

DEFF Research Database (Denmark)

Nielsen, Mogens; Rozenberg, Grzegorz; Salomaa, Arto

1974-01-01

Continuing the work begun in Part I of this paper, we consider now variations of nondeterministic OL-systems. The present Part II of the paper contains a systematic classification of the effect of nonterminals, codings, weak codings, nonerasing homomorphisms and homomorphisms for all basic variat...

Nonterminals and codings in defining variations of OL-systems

DEFF Research Database (Denmark)

Skyum, Sven

1974-01-01

The use of nonterminals versus the use of codings in variations of OL-systems is studied. It is shown that the use of nonterminals produces a comparatively low generative capacity in deterministic systems while it produces a comparatively high generative capacity in nondeterministic systems. Fina....... Finally it is proved that the family of context-free languages is contained in the family generated by codings on propagating OL-systems with a finite set of axioms, which was one of the open problems in [10]. All the results in this paper can be found in [71] and [72].......The use of nonterminals versus the use of codings in variations of OL-systems is studied. It is shown that the use of nonterminals produces a comparatively low generative capacity in deterministic systems while it produces a comparatively high generative capacity in nondeterministic systems...

Adult sex ratio variation : Implications for breeding system evolution

NARCIS (Netherlands)

Szekely, T.; Weissing, F. J.; Komdeur, J.

Adult sex ratio (ASR) exhibits immense variation in nature, although neither the causes nor the implications of this variation are fully understood. According to theory, the ASR is expected to influence sex roles and breeding systems, as the rarer sex in the population has more potential partners to

Balance Systems and the Variational Bicomplex

Directory of Open Access Journals (Sweden)

Serge Preston

2011-07-01

Full Text Available In this work we show that the systems of balance equations (balance systems of continuum thermodynamics occupy a natural place in the variational bicomplex formalism. We apply the vertical homotopy decomposition to get a local splitting (in a convenient domain of a general balance system as the sum of a Lagrangian part and a complemental ''pure non-Lagrangian'' balance system. In the case when derivatives of the dynamical fields do not enter the constitutive relations of the balance system, the ''pure non-Lagrangian'' systems coincide with the systems introduced by S. Godunov [Soviet Math. Dokl. 2 (1961, 947-948] and, later, asserted as the canonical hyperbolic form of balance systems in [Müller I., Ruggeri T., Rational extended thermodynamics, 2nd ed., Springer Tracts in Natural Philosophy, Vol. 37, Springer-Verlag, New York, 1998].

The relationship between carbonate facies, volcanic rocks and plant remains in a late Palaeozoic lacustrine system (San Ignacio Fm, Frontal Cordillera, San Juan province, Argentina)

Science.gov (United States)

Busquets, P.; Méndez-Bedia, I.; Gallastegui, G.; Colombo, F.; Cardó, R.; Limarino, O.; Heredia, N.; Césari, S. N.

2013-07-01

The San Ignacio Fm, a late Palaeozoic foreland basin succession that crops out in the Frontal Cordillera (Argentinean Andes), contains lacustrine microbial carbonates and volcanic rocks. Modification by extensive pedogenic processes contributed to the massive aspect of the calcareous beds. Most of the volcanic deposits in the San Ignacio Fm consist of pyroclastic rocks and resedimented volcaniclastic deposits. Less frequent lava flows produced during effusive eruptions led to the generation of tabular layers of fine-grained, greenish or grey andesites, trachytes and dacites. Pyroclastic flow deposits correspond mainly to welded ignimbrites made up of former glassy pyroclasts devitrified to microcrystalline groundmass, scarce crystals of euhedral plagioclase, quartz and K-feldspar, opaque minerals, aggregates of fine-grained phyllosilicates and fiammes defining a bedding-parallel foliation generated by welding or diagenetic compaction. Widespread silicified and silica-permineralized plant remains and carbonate mud clasts are found, usually embedded within the ignimbrites. The carbonate sequences are underlain and overlain by volcanic rocks. The carbonate sequence bottoms are mostly gradational, while their tops are usually sharp. The lower part of the carbonate sequences is made up of mud which appear progressively, filling interstices in the top of the underlying volcanic rocks. They gradually become more abundant until they form the whole of the rock fabric. Carbonate on volcanic sandstones and pyroclastic deposits occur, with the nucleation of micritic carbonate and associated production of pyrite. Cyanobacteria, which formed the locus of mineral precipitation, were related with this nucleation. The growth of some of the algal mounds was halted by the progressive accumulation of volcanic ash particles, but in most cases the upper boundary is sharp and suddenly truncated by pyroclastic flows or volcanic avalanches. These pyroclastic flows partially destroyed the

Microscopic description of nuclear few-body systems with the stochastic variational method

International Nuclear Information System (INIS)

Suzuki, Yasuyuki

2000-01-01

A simple gambling procedure called the stochastic variational method can be applied, together with appropriate variational trial functions, to solve a few-body system where the correlation between the constituents plays an important role in determining its structure. The usefulness of the method is tested by comparing to other accurate solutions for Coulombic systems. Examples of application shown here include few-nucleon systems interacting with realistic forces and few-cluster systems with the Pauli principle being taken into account properly. These examples confirm the power of the stochastic variational method. There still remain many problems for extending to a system consisting of more particles. (author)

Quality and petrographic characteristics of the lacustrine Ermenek coal (early Miocene), Turkey

Energy Technology Data Exchange (ETDEWEB)

Demirel, I.H.; Karayigit, A.I. [Hacettepe Univ., Beytepe-Ankara (Turkey). Dept. of Geological Engineering

1999-05-01

The early Miocene Yenimahalle Formation including alluvial-lacustrine sediments and a mineable coal steam with an average of 5 m in thickness rests unconformably upon the basement and is also unconformably overlain by marine limestones of the middle-late Miocene Mut Formation in the Ermenek coal basin. The coal basin in the present study has been subdivided into two areas, Canakci and Pamuklu-Tepebasi, which are separated by the basement and a fault, in order to determine coal properties in detail. The investigated subbituminous coals with an average of 0.40%Ro huminite reflectance often contain gastropod shells (Planorbidae) which commonly maintain the original aragonite and calcite composition. The coals have similar chemical properties and petrographic composition in the two areas, but their sulphur contents are clearly different. In the Canakci area the coals on an air-dried basis contain distinctly less total sulphur (avg. 1.3%) and organic sulphur contents (0.13--0.15%) than in the Pamuklu-Tepebasi area (avg. 4.5% and 4.25%, respectively). This difference is interpreted to be controlled by mire chemistry and sedimentation during peat formation.

Geographic variation in Medicare and the military healthcare system.

Science.gov (United States)

Adesoye, Taiwo; Kimsey, Linda G; Lipsitz, Stuart R; Nguyen, Louis L; Goodney, Philip; Olaiya, Samuel; Weissman, Joel S

2017-08-01

To compare geographic variation in healthcare spending and utilization between the Military Health System (MHS) and Medicare across hospital referral regions (HRRs). Retrospective analysis. Data on age-, sex-, and race-adjusted Medicare per capita expenditure and utilization measures by HRR were obtained from the Dartmouth Atlas for 2007 to 2010. Similarly, adjusted data from 2007 and 2010 were obtained from the MHS Data Repository and patients assigned to HRRs. We compared high- and low-spending regions, and computed coefficient of variation (CoV) and correlation coefficients for healthcare spending, hospital inpatient days, hip surgery, and back surgery between MHS and Medicare patients. We found significant variation in spending and utilization across HRRs in both the MHS and Medicare. CoV for spending was higher in the MHS compared with Medicare, (0.24 vs 0.15, respectively) and CoV for inpatient days was 0.36 in the MHS versus 0.19 in Medicare. The CoV for back surgery was also greater in the MHS compared with Medicare (0.47 vs 0.29, respectively). Per capita Medicare spending per HRR was significantly correlated to adjusted MHS spending (r = 0.3; P spending markets in both systems were not comparable; lower spending markets were located mostly in the Midwest. In comparing 2 systems with similar pricing schemes, differences in spending likely reflect variation in utilization and the influence of local provider culture.

Analysis of soft-sediment deformation structures in Neogene fluvio-lacustrine deposits of Çaybağı Formation, Eastern Turkey

Science.gov (United States)

Koç Taşgin, Calibe; Türkmen, İbrahim

2009-06-01

During the Neogene, both strike-slip and extensional regimes coexisted in eastern Turkey and, a number of fault-bounded basins associated with the East Anatolian Fault System developed. The Çaybağı Formation (Late Miocene-Early Pliocene) deposited in one of these basins consists of fluvio-lacustrine deposits. Numerous soft-sediment deformation structures are encountered in this formation, particularly in conglomerates, medium- to coarse-grained tuffaceous sandstones and claystones: folded structures (slumps, convolute laminations, and simple recumbent folds), water-escape structures (intruded sands, internal cusps, interpenetrative cusps and sand volcanoes), and load structures (load casts, pseudonodules, flame structures, and pillow structures). These structures are produced by liquefaction and/or fluidization of the unconsolidated sediments during a seismic shock. Consequently, the existence of seismically-induced deformation structures in the Çaybağı Formation and the association with a Neogene intraformational unconformity, growth faults, and reverse faults in the Çaybağı basin attest to the tectonic activity in this area during the Late Miocene and Early Pliocene. The East Anatolian Fault System, in particular the Uluova fault zone, is the most probable seismogenic source. Earthquakes with a magnitude of over 5 in the Richter scale can be postulated.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Earth System Science. Soumen Sarkar. Articles written in Journal of Earth System Science. Volume 114 Issue 3 June 2005 pp 303-323. Evidence of lacustrine sedimentation in the Upper Permian Bijori Formation, Satpura Gondwana basin: Palaeogeographic and tectonic implications.

Probabilistic frequency variations of structure-soil systems

International Nuclear Information System (INIS)

Hamilton, C.W.; Hadjian, A.H.

1976-01-01

During earthquakes, structure-soil systems act as filters greatly amplifying the response of equipment whose frequencies are at or near their natural frequencies. Thus, the estimation of these structure-soil system frequencies assumes significant importance both for safety and cost. Actual in-situ frequencies of structures differ from calculated frequencies due both to variations in mathematical modelling techniques and to variations of material properties. This paper studies the second source only. This variability is usually gauged by the 'worst case' analyses technique in which extreme high- and low- parameter values are assumed and the associated frequencies are used as upper and lower bounds. This approach is not entirely satisfactory because it does not provide any indication of the probability of these limits being exceeded, of the distribution between these limits, or of the level of conservation introduced into the design process. The present approach provides this additional information. The emphasis in this part is both on developing the methodology and on the results obtained. It covers both the fixed-base structure and the effects of soil-structure interaction. Empirical data on concrete proerties were obtained from previously published results. Much less is known about variability of soil properties, so the soil structure interaction coefficients are assumed to be normally distributed. As data on the variation of soil properties become available, they can be readily incorporated via the methodology developed here. (Auth.)

Historical variations of Bera Lake (Malaysia) sediments geochemistry using radioisotopes and sediment quality indices

International Nuclear Information System (INIS)

Mohammadreza Gharibreza; John Kuna Raj; Ismail Yusoff; Zainudin Othman; Wan Zakaria Wan Muhamad Tahir; Muhammad Aqeel Ashraf

2013-01-01

The Bera Lake basin is a lacustrine mire system and the largest natural lake in Peninsular Malaysia. Three cores were collected from the lake sediments in order to assess sediment quality and ecological risks for aquatic life and human health. An index analysis approach (C f , C d , E r , and IR) and fallout 210 Pb and 137 Cs radioisotopes were applied to assess the impacts of environmental evolutionary changes. Sediment chronology was determined using the Constant Rate of Supply model with the resultant ages verified by 137 Cs horizons. Although the general contamination factors indicate low risk conditions in Bera Lake the risks associated with individual layers ranged from moderate to considerable. Five deforestation phases can be identified in the dated sediment cores with distinct variations in heavy metal influxes since 1972. These phases are in excellent agreement with the dates of land clearance and development projects undertaken over the past four decades. This study has highlighted the capability of contamination factors and chronological methods in environmental evolutionary studies where catchments have experienced extensive land use changes. The destiny of heavy metal influxes into a lake can also be revealed using this methodology. (author)

Long-term behaviour of {sup 137}Cs in the lacustrine ecosystem of lake Viverone; Il comportamento a lungo termine del {sup 137}Cs nell`ecosistema lacustre del lago di Viverone

Energy Technology Data Exchange (ETDEWEB)

Spezzano, P.; Cerea, E.; Massironi, L.; Olivetta, A.; Bortoluzzi, S.; Nocente, M.; Berton, G. [ENEA, Centro Ricerche Saluggia, Vercelli (Italy). Dip. Ambiente

1998-12-31

For the evaluation of long term behaviour of {sup 137}Cs in a lacustrine ecosystem, for ten years after the Chernobyl nuclear accident several experimental studies have been conducted in the Viverone lake, a small, eutrophic, monomictic lake situated between Turin and Vercelli, in North-West Italy. Radiocaesium activities were measured in different components of the ecosystem, i.e. soil, water, sediment and biotas, and have been related with main environmental physico-chemical parameters. Changes in radiocaesium content with time provided information about transfer processes of this radionuclide into the lacustrine ecosystem. Levels of {sup 137}Cs in lake water after several years from deposition can be ascribed to the migration from catchment basin and to the remobilization from bottom sediments. However, experimental results do not allow to ascertain which of these two factors prevails over the other.

Past Holocene detritism quantification and modeling from lacustrine archives in order to deconvoluate human-climate interactions on natural ecosystem over long time-scale

Science.gov (United States)

Simonneau, Anaëlle; Chapron, Emmanuel; Di Giovanni, Christian; Galop, Didier; Darboux, Frédéric

2014-05-01

Water budget is one of the main challenges to paleoclimate researchers in relation to present-day global warming and its consequences for human societies. Associated soil degradation and erosion are thereby becoming a major concern in many parts of the world and more particularly in the Alps. Moreover, humans are considered as geomorphologic agents since few thousand years and it is now recognized that such an impact on natural ecosystem profoundly modified soils properties as well as aquatic ecosystems dynamics over long-term periods. The quantification of such inference over long time-scale is therefore essential to establish new policies to reduce mechanic soil erosion, which is one of the dominant processes in Europe, and anticipate the potential consequences of future climate change on hydric erosion. The mechanical erosion of continental surfaces results from climatic forcing, but can be amplified by the anthropogenic one. We therefore suggest that quantifying and modelling soil erosion processes within comparable Holocene lacustrine archives, allows to estimate and date which and when past human activities have had an impact on soil fluxes over the last 10000 years. Based on the present-day geomorphology of the surrounding watershed and the evolution of the vegetation cover during the Holocene, we develop an interdisciplinary approach combining quantitative organic petrography (i.e. optical characterization and quantification of soil particles within lake sediments) with high-resolution seismic profiling, age-depth models on lacustrine sediment cores and soil erosional susceptibility modeling, in order to estimate the annual volume of soil eroded over the last 10000 years, and in fine to quantify the volume of human-induced soil erosion during the Holocene period. This method is applied to close but contrasted mountainous lacustrine environments from the western French Alps: lakes Blanc Huez and Paladru, sensitive to same climatic influences but where past

Paleo and present-day chemical weathering in lacustrine and riverine sediments in Northern Patagonia, Argentina

Energy Technology Data Exchange (ETDEWEB)

Roman Ross, Gabriela [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche. Lab. de Analisis por Activacion Neutronica; Arribere, Maria A.; Guevara, Sergio Ribeiro [Universidad Nacional de Cuyo, XX (Argentina)

1996-07-01

Neutron activation analysis was used to study the abundance, distribution and fraction of REE (Rare Earth Elements) and diagnostic elements (Th, Co, Cr, Sc, Rb, Sr) in sediments from Mascardi lake and Upper Manso river. The local weathering patterns of this watershed show a strong influence of volcanic rocks with a selective mobilization of the more soluble elements. These patterns are very similar to those observed in a sedimentary lacustrine core from Mascardi lake. Paleolimnological record indicates a change in local fluxes of water and sediments, and an increase in organic matter content since the last full-glacial maximum. However, the chemical composition of the sedimentary inputs has not changed significantly during the last 14000 years. Our data support the hypothesis that present-day and Holocene chemical weathering have similar characteristics. All of the above conclusions are based on geochemical parameters only. (author)

Paleo and present-day chemical weathering in lacustrine and riverine sediments in Northern Patagonia, Argentina

International Nuclear Information System (INIS)

Roman Ross, Gabriela

1996-01-01

Neutron activation analysis was used to study the abundance, distribution and fraction of REE (Rare Earth Elements) and diagnostic elements (Th, Co, Cr, Sc, Rb, Sr) in sediments from Mascardi lake and Upper Manso river. The local weathering patterns of this watershed show a strong influence of volcanic rocks with a selective mobilization of the more soluble elements. These patterns are very similar to those observed in a sedimentary lacustrine core from Mascardi lake. Paleolimnological record indicates a change in local fluxes of water and sediments, and an increase in organic matter content since the last full-glacial maximum. However, the chemical composition of the sedimentary inputs has not changed significantly during the last 14000 years. Our data support the hypothesis that present-day and Holocene chemical weathering have similar characteristics. All of the above conclusions are based on geochemical parameters only. (author)

Quality and petrographic characteristics of the Lacustrine Ermenek Coal (Early Miocene), Turkey

Energy Technology Data Exchange (ETDEWEB)

Demirel, I.H.; Karayigit, A.I.

1999-04-15

The early Miocene Yenimahalle Formation including alluvial-lacustrine sediments and a mineable coal seam with an average of 5 m in thickness rests unconformably upon the basement and is also unconformably overlain by marine limestones of the middle-late Miocene Mut Formation in the Ermenek coal basin. The coal basin in the present study has been subdivided into two areas, Canakci and Pamuklu-Tepebasi, which are separated by the basement and a fault, in order to determine coal properties in detail. The investigated subbituminous coals with an average of 0.40% Ro huminite reflectance often contain gastropod shells (Planorbidae) which commonly maintain the original aragonite and calcite composition. The coals have similar chemical properties and petrographic composition in the two areas, but their sulphur contents are clearly different. In the Canakci area the coals on an air-dried basis contain distinctly less total sulphur (avg. 1.3%) and organic sulphur contents (0.13 0.15%) than in the Pamuklu-Tepebasi area (avg. 4.5% and 4.25%, respectively). This difference is interpreted to be controlled by mire chemistry and sedimentation during peat formation. (author)

On the foundation of a variational principle for decaying systems

International Nuclear Information System (INIS)

Szasz, G.I.

1976-01-01

Taking into account the circumstances that the decay of an unstable microscopic system into two fragments is established by the counting of one of the decay products in a detector, the observed exponential decay law then asserts only knowledge of the spatiotemporal behaviour of the probability density (and therewith knowledge of the decaying state) at a large finite distance from the site of decay. We therefore formulate a variational principle, of which stationary functions show this decay behaviour. In addition to the resonant wave functions there are also solutions of the variational principle, which decrease exponentially with increasing distance, i.e., functions which could be used to describe the bound states. As the time-dependent treatment shows, the decaying states cannot occur in isolation in a scattering process. The mathematical characterisation of the decaying states via a variational principle is incorporated in a theory of open physical systems. In contradiction to the variational principle of Schroedinger our principle does not provide complete knowledge of the quantum states, but this is not needed in order to describe the decay. (orig.) [de

Adult sex ratio variation: implications for breeding system evolution.

Science.gov (United States)

Székely, T; Weissing, F J; Komdeur, J

2014-08-01

Adult sex ratio (ASR) exhibits immense variation in nature, although neither the causes nor the implications of this variation are fully understood. According to theory, the ASR is expected to influence sex roles and breeding systems, as the rarer sex in the population has more potential partners to mate with than the more common sex. Changes in mate choice, mating systems and parental care suggest that the ASR does influence breeding behaviour, although there is a need for more tests, especially experimental ones. In the context of breeding system evolution, the focus is currently on operational sex ratios (OSRs). We argue that the ASR plays a role of similar importance and urge researchers to study the ASR and the OSR side by side. Finally, we plead for a dynamic view of breeding system evolution with feedbacks between mating, parenting, OSR and ASR on both ecological and evolutionary time scales. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Round-Trip System Available to Measure Path Length Variation in Korea VLBI System for Geodesy

Science.gov (United States)

Oh, Hongjong; Kondo, Tetsuro; Lee, Jinoo; Kim, Tuhwan; Kim, Myungho; Kim, Suchul; Park, Jinsik; Ju, Hyunhee

2010-01-01

The construction project of Korea Geodetic VLBI officially started in October 2008. The construction of all systems will be completed by the end of 2011. The project was named Korea VLBI system for Geodesy (KVG), and its main purpose is to maintain the Korea Geodetic Datum. In case of the KVG system, an observation room with an H-maser frequency standard is located in a building separated from the antenna by several tens of meters. Therefore KVG system will adopt a so-called round-trip system to transmit reference signals to the antenna with reduction of the effect of path length variations. KVG s round-trip system is designed not only to use either metal or optical fiber cables, but also to measure path length variations directly. We present this unique round trip system for KVG.

Methodology for dimensional variation analysis of ITER integrated systems

International Nuclear Information System (INIS)

Fuentes, F. Javier; Trouvé, Vincent; Cordier, Jean-Jacques; Reich, Jens

2016-01-01

Highlights: • Tokamak dimensional management methodology, based on 3D variation analysis, is presented. • Dimensional Variation Model implementation workflow is described. • Methodology phases are described in detail. The application of this methodology to the tolerance analysis of ITER Vacuum Vessel is presented. • Dimensional studies are a valuable tool for the assessment of Tokamak PCR (Project Change Requests), DR (Deviation Requests) and NCR (Non-Conformance Reports). - Abstract: The ITER machine consists of a large number of complex systems highly integrated, with critical functional requirements and reduced design clearances to minimize the impact in cost and performances. Tolerances and assembly accuracies in critical areas could have a serious impact in the final performances, compromising the machine assembly and plasma operation. The management of tolerances allocated to part manufacture and assembly processes, as well as the control of potential deviations and early mitigation of non-compliances with the technical requirements, is a critical activity on the project life cycle. A 3D tolerance simulation analysis of ITER Tokamak machine has been developed based on 3DCS dedicated software. This integrated dimensional variation model is representative of Tokamak manufacturing functional tolerances and assembly processes, predicting accurate values for the amount of variation on critical areas. This paper describes the detailed methodology to implement and update the Tokamak Dimensional Variation Model. The model is managed at system level. The methodology phases are illustrated by its application to the Vacuum Vessel (VV), considering the status of maturity of VV dimensional variation model. The following topics are described in this paper: • Model description and constraints. • Model implementation workflow. • Management of input and output data. • Statistical analysis and risk assessment. The management of the integration studies based on

Methodology for dimensional variation analysis of ITER integrated systems

Energy Technology Data Exchange (ETDEWEB)

Fuentes, F. Javier, E-mail: FranciscoJavier.Fuentes@iter.org [ITER Organization, Route de Vinon-sur-Verdon—CS 90046, 13067 St Paul-lez-Durance (France); Trouvé, Vincent [Assystem Engineering & Operation Services, rue J-M Jacquard CS 60117, 84120 Pertuis (France); Cordier, Jean-Jacques; Reich, Jens [ITER Organization, Route de Vinon-sur-Verdon—CS 90046, 13067 St Paul-lez-Durance (France)

2016-11-01

Highlights: • Tokamak dimensional management methodology, based on 3D variation analysis, is presented. • Dimensional Variation Model implementation workflow is described. • Methodology phases are described in detail. The application of this methodology to the tolerance analysis of ITER Vacuum Vessel is presented. • Dimensional studies are a valuable tool for the assessment of Tokamak PCR (Project Change Requests), DR (Deviation Requests) and NCR (Non-Conformance Reports). - Abstract: The ITER machine consists of a large number of complex systems highly integrated, with critical functional requirements and reduced design clearances to minimize the impact in cost and performances. Tolerances and assembly accuracies in critical areas could have a serious impact in the final performances, compromising the machine assembly and plasma operation. The management of tolerances allocated to part manufacture and assembly processes, as well as the control of potential deviations and early mitigation of non-compliances with the technical requirements, is a critical activity on the project life cycle. A 3D tolerance simulation analysis of ITER Tokamak machine has been developed based on 3DCS dedicated software. This integrated dimensional variation model is representative of Tokamak manufacturing functional tolerances and assembly processes, predicting accurate values for the amount of variation on critical areas. This paper describes the detailed methodology to implement and update the Tokamak Dimensional Variation Model. The model is managed at system level. The methodology phases are illustrated by its application to the Vacuum Vessel (VV), considering the status of maturity of VV dimensional variation model. The following topics are described in this paper: • Model description and constraints. • Model implementation workflow. • Management of input and output data. • Statistical analysis and risk assessment. The management of the integration studies based on

Geomorphic Drainage Capture Recorded by Oxygen Isotopes of Green River Formation Lacustrine Mudstone, Eocene, Wyoming

Science.gov (United States)

Doebbert, A. C.; Booth, A. L.; Carroll, A.; Chamberlain, C.; Rhodes, M.

2005-12-01

The isotopic composition of cement and other meteoric precipitates are increasingly being used to interpret orogenic uplift histories, based on the relationship between altitude and rainwater δ18O. However, other variables such as changing regional drainage patterns may also affect the downstream composition of surface waters, especially when multiple drainages commingle in a lake. The Green River Formation contains some of the best documented lacustrine deposits in the world, making it ideal for examining such issues. Carbonate mudstone in balanced-fill facies of the lower LaClede Bed averages 3.41‰ (PDB), and records a deep, saline to brackish lake that fluctuated near its sill. In contrast, overfilled facies of the upper LaClede Bed record a freshwater lake, and δ18O reaches values as low as -9.72‰. This transition occurred shortly after deposition of the Analcite Tuff at 48.94 ± 0.12 Ma (Smith et al., 2003), and was geologically abrupt. Based on 40Ar/39Ar-calibrated sediment accumulation rates it required no more than 200-300 ky. An almost identical transition occurs in two cores separated by about 30 km, making local diagenesis an unlikely cause. The magnitude of δ18O change is similar to that in some uplift studies, but its rapidity virtually excludes uplift as a controlling mechanism. Instead, we propose that both the change in sedimentation and the sharp decrease in δ18O are the result of a drainage capture event. The addition of a new drainage to the basin may have adjusted isotopic values in two ways: by introducing runoff with relatively low δ18O, and by decreasing residence time (and therefore evaporation) of lake water. Decreasing 87Sr/86Sr across the same transition suggests that the newly added waters may have been sourced from rising volcanic topography to the north in the Absaroka province. Although this rising topography allows for the possibility of some uplift component, the rate of change in lacustrine δ18O is consistent with

Assessment of Radiation Background Variation for Moving Detection Systems

Energy Technology Data Exchange (ETDEWEB)

Miller, James Christopher [Los Alamos National Laboratory; Rennie, John Alan [Los Alamos National Laboratory; Toevs, James Waldo [Los Alamos National Laboratory; Wallace, Darrin J. [Los Alamos National Laboratory; Abhold, Mark Edward [Los Alamos National Laboratory

2015-07-13

The introduction points out that radiation backgrounds fluctuate across very short distances: factors include geology, soil composition, altitude, building structures, topography, and other manmade structures; and asphalt and concrete can vary significantly over short distances. Brief descriptions are given of the detection system, experimental setup, and background variation measurements. It is concluded that positive and negative gradients can greatly reduce the detection sensitivity of an MDS: negative gradients create opportunities for false negatives (nondetection), and positive gradients create a potentially unacceptable FAR (above 1%); the location of use for mobile detection is important to understand; spectroscopic systems provide more information for screening out false alarms and may be preferred for mobile use; and mobile monitor testing at LANL accounts for expected variations in the background.

Noether's Theorem and its Inverse of Birkhoffian System in Event Space Based on Herglotz Variational Problem

Science.gov (United States)

Tian, X.; Zhang, Y.

2018-03-01

Herglotz variational principle, in which the functional is defined by a differential equation, generalizes the classical ones defining the functional by an integral. The principle gives a variational principle description of nonconservative systems even when the Lagrangian is independent of time. This paper focuses on studying the Noether's theorem and its inverse of a Birkhoffian system in event space based on the Herglotz variational problem. Firstly, according to the Herglotz variational principle of a Birkhoffian system, the principle of a Birkhoffian system in event space is established. Secondly, its parametric equations and two basic formulae for the variation of Pfaff-Herglotz action of a Birkhoffian system in event space are obtained. Furthermore, the definition and criteria of Noether symmetry of the Birkhoffian system in event space based on the Herglotz variational problem are given. Then, according to the relationship between the Noether symmetry and conserved quantity, the Noether's theorem is derived. Under classical conditions, Noether's theorem of a Birkhoffian system in event space based on the Herglotz variational problem reduces to the classical ones. In addition, Noether's inverse theorem of the Birkhoffian system in event space based on the Herglotz variational problem is also obtained. In the end of the paper, an example is given to illustrate the application of the results.

Shahejie-Shahejie/Guantao/Wumishan and Carboniferous/Permian Coal-Paleozoic Total Petroleum Systems in the Bohaiwan Basin, China (based on geologic studies for the 2000 World Energy Assessment Project of the U.S. Geological Survey)

Science.gov (United States)

Ryder, Robert T.; Qiang, Jin; McCabe, Peter J.; Nuccio, Vito F.; Persits, Felix

2012-01-01

This report discusses the geologic framework and petroleum geology used to assess undiscovered petroleum resources in the Bohaiwan basin province for the 2000 World Energy Assessment Project of the U.S. Geological Survey. The Bohaiwan basin in northeastern China is the largest petroleum-producing region in China. Two total petroleum systems have been identified in the basin. The first, the Shahejie&ndashShahejie/Guantao/Wumishan Total Petroleum System, involves oil and gas generated from mature pods of lacustrine source rock that are associated with six major rift-controlled subbasins. Two assessment units are defined in this total petroleum system: (1) a Tertiary lacustrine assessment unit consisting of sandstone reservoirs interbedded with lacustrine shale source rocks, and (2) a pre-Tertiary buried hills assessment unit consisting of carbonate reservoirs that are overlain unconformably by Tertiary lacustrine shale source rocks. The second total petroleum system identified in the Bohaiwan basin is the Carboniferous/Permian Coal–Paleozoic Total Petroleum System, a hypothetical total petroleum system involving natural gas generated from multiple pods of thermally mature coal beds. Low-permeability Permian sandstones and possibly Carboniferous coal beds are the reservoir rocks. Most of the natural gas is inferred to be trapped in continuous accumulations near the center of the subbasins. This total petroleum system is largely unexplored and has good potential for undiscovered gas accumulations. One assessment unit, coal-sourced gas, is defined in this total petroleum system.

The inverse problem of the calculus of variations for discrete systems

Science.gov (United States)

Barbero-Liñán, María; Farré Puiggalí, Marta; Ferraro, Sebastián; Martín de Diego, David

2018-05-01

We develop a geometric version of the inverse problem of the calculus of variations for discrete mechanics and constrained discrete mechanics. The geometric approach consists of using suitable Lagrangian and isotropic submanifolds. We also provide a transition between the discrete and the continuous problems and propose variationality as an interesting geometric property to take into account in the design and computer simulation of numerical integrators for constrained systems. For instance, nonholonomic mechanics is generally non variational but some special cases admit an alternative variational description. We apply some standard nonholonomic integrators to such an example to study which ones conserve this property.

Study of bond-energy variations in molecular systems under irradiation; Etude de la variation de l'energie de liaison dans les systemes moleculaires irradies

Energy Technology Data Exchange (ETDEWEB)

Naudet, G; Passe, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

On the basis of experimental results selected from publications, the evolution of the bond energy of a molecular system under irradiation - leading to a more or less bound state - is studied. This variation of bond energy is then compared to the total bond energy of the initial system and to the energy absorbed in the system during the irradiation. This is done as a function of the nature of molecular system and the radiation spectrum and intensity. Our working method will first be explained, and the results obtained will then be given. (authors) [French] A l'aide de resultats experimentaux, selectionnes dans les publications, nous etudions l'evolution de l'energie de liaison d'un systeme moleculaire sous irradiation (evolution vers un etat plus ou moins lie), et nous comparons cette variation d'energie de liaison a l'energie totale de liaison du systeme initial et a l'energie absorbee dans le systeme au cours de l'irradiation. Ceci est fait en fonction de la nature du systeme moleculaire ainsi que du spectre et de l'intensite du rayonnement. Nous exposons d'abord notre methode de travail, puis les resultats obtenus. (auteurs)

Habitat-related specialization of lateral-line system morphology in a habitat-generalist and a habitat-specialist New Zealand eleotrid.

Science.gov (United States)

Vanderpham, J P; Nakagawa, S; Senior, A M; Closs, G P

2016-04-01

An investigation of intraspecific habitat-related patterns of variation in oculoscapular lateral-line superficial neuromasts (SN) identified a decrease in the ratio of total SNs to pores, and a trend towards decreased asymmetry in SNs in the habitat-generalist common bully Gobiomorphus cotidianus from fluvial habitats compared to lacustrine habitats, suggesting habitat-related phenotypic variability. A greater ratio of pores to SNs, as well as less variation in the total number and asymmetry of SNs observed in the fluvial habitat-specialist redfin bully Gobiomorphus huttoni may provide further evidence of variations in the oculoscapular lateral-line morphology of fluvial habitat G. cotidianus individuals serving as adaptations to more turbulent environments. © 2016 The Fisheries Society of the British Isles.

A high-resolution Early Holocene-late MIS 3 environmental rock- and palaeomagnetic record from Lake Sf. Ana, Carpathian Mts, Romania

Directory of Open Access Journals (Sweden)

Daniel VERES

2014-11-01

Full Text Available Lacustrine sediments are excellent sources of palaeoenvironmental and palaeoclimatic information because they usually provide continuous and high-resolution records. In centraleastern Europe however lacustrine records that extend beyond the Holocene are rather sparse.Palaeomagnetic records from this region are also insufficiently explored, and usually associated with terrestrial deposits such as loess. In this context, the lacustrine record of Lake Sf. Ana, a volcanic crater lake in the East Carpathians, Romania, provides an important archive for reconstructing past paleomagnetic secular variation in the region from early Holocene to late Marine Isotope Stage (MIS 3.

Record of palaeoenvironmental changes in a Lower Permian organic-rich lacustrine succession: Integrated sedimentological and geochemical study of the Rudník member, Krkonoše Piedmont Basin, Czech Republic

Czech Academy of Sciences Publication Activity Database

Martínek, K.; Blecha, M.; Daněk, V.; Franců, J.; Hladíková, J.; Johnová, R.; Uličný, David

2006-01-01

Roč. 230, 1/2 (2006), s. 85-128 ISSN 0031-0182 R&D Projects: GA ČR GA205/94/0692 Institutional research plan: CEZ:AV0Z30120515 Keywords : Lower Permian * Bohemian Massif * lacustrine facies Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.822, year: 2006

Variation in Payment Rates under Medicare's Inpatient Prospective Payment System.

Science.gov (United States)

Krinsky, Sam; Ryan, Andrew M; Mijanovich, Tod; Blustein, Jan

2017-04-01

To measure variation in payment rates under Medicare's Inpatient Prospective Payment System (IPPS) and identify the main payment adjustments that drive variation. Medicare cost reports for all Medicare-certified hospitals, 1987-2013, and Dartmouth Atlas geographic files. We measure the Medicare payment rate as a hospital's total acute inpatient Medicare Part A payment, divided by the standard IPPS payment for its geographic area. We assess variation using several measures, both within local markets and nationally. We perform a factor decomposition to identify the share of variation attributable to specific adjustments. We also describe the characteristics of hospitals receiving different payment rates and evaluate changes in the magnitude of the main adjustments over time. Data downloaded from the Centers for Medicare and Medicaid Services, the National Bureau of Economic Research, and the Dartmouth Atlas. In 2013, Medicare paid for acute inpatient discharges at a rate 31 percent above the IPPS base. For the top 10 percent of discharges, the mean rate was double the IPPS base. Variations were driven by adjustments for medical education and care to low-income populations. The magnitude of variation has increased over time. Adjustments are a large and growing share of Medicare hospital payments, and they create significant variation in payment rates. © Health Research and Educational Trust.

Transit Duration Variations due to Secular Interactions in Systems with Tightly-packed Inner Planets

Science.gov (United States)

Boley, Aaron; Van Laerhoven, Christa; Granados Contreras, A. Paula

2018-04-01

Secular interactions among planets in multi-planet systems will lead to variations in orbital inclinations and to the precession of orbital nodes. Taking known system architectures at face value, we calculate orbital precession rates for planets in tightly-packed systems using classical second-order secular theory, in which the orientation of the orbits can be described as a vector sum of eigenmodes and the eigenstructure is determined only by the masses and semi-major axes of the planets. Using this framework, we identify systems that have fast precession frequencies, and use those systems to explore the range of transit duration variation that could occur using amplitudes that are consistent with tightly-packed planetary systems. We then further assess how transit duration variations could be used in practice.

Holocene environmental changes in northern Lebanon as inferred from a multiproxy study on lacustrine-palustrine sediment

Science.gov (United States)

Vidal, Laurence; Jenna, Hage-Hassen; Demory, François; Develle, Anne-Lise; van Campo, Elise; Elias, Ata

2016-04-01

The reconstruction of the Levantine post-glacial environmental evolution is essential to understand the interactions between variability of regional water cycle, dynamics of the global climate, and cultural evolution. We present a paleolacustrine record from the karstic Yammouneh basin (34.06N-34.09N; 36.0E-36.03E, 1360 m a.s.l.), located on the eastern flank of Mount Lebanon (northern Levant). Holocene sediments (retrieved from gully and a trenbch) (1.5 to 3.6 m thick) consist of pale lacustrine chalk interrupted by an ash layer and remarkable centimetric beds of ocher to dark brown silty clays used, in addition to 14C ages, as stratigraphical markers. Lacustrine biogenic remains are diversified and abundant (ostracods, gastropods, charophytes, chlorophyceae, plant debris…) all reflecting a freswater, generally shallow waterbody. We analysed the sediment mineralogy and geochemistry, TOM contents, magnetic properties, pollen and calcite oxygen isotope composition derived from ostracod shells. These sequences are compared to former data from 2 trenches and 1 core collected in different points of the basin (Daeron et al., 2007; Develle et al., 2009, 2010). A total of 42 AMS 14C dating (partly carbonized wood) provide a solid chronology from the YD to present. Results reveal the following main features : 1- intervals dominated by authigenic calcite suggest that the major water supply was the karstic springs, which still deliver Ca-rich water and low surface runoff; 2- the lake oxygen isotope composition has been impacted by the source isotope composition throughout the Holocene and by increased inland rainfall during the early Holocene; 3- a decideous oak forest, implying much more soil water availability than today, was developed around the lake from ca. 11.5 to 9.5 kyr (the very bad pollen preservation after 8.3 kyr reflects oxidation or frequent oscillations of the water level); 4- four paleosols evidenced from lithofacies and magnetic properties are identified

A variational method in out-of-equilibrium physical systems.

Science.gov (United States)

Pinheiro, Mario J

2013-12-09

We propose a new variational principle for out-of-equilibrium dynamic systems that are fundamentally based on the method of Lagrange multipliers applied to the total entropy of an ensemble of particles. However, we use the fundamental equation of thermodynamics on differential forms, considering U and S as 0-forms. We obtain a set of two first order differential equations that reveal the same formal symplectic structure shared by classical mechanics, fluid mechanics and thermodynamics. From this approach, a topological torsion current emerges of the form , where Aj and ωk denote the components of the vector potential (gravitational and/or electromagnetic) and where ω denotes the angular velocity of the accelerated frame. We derive a special form of the Umov-Poynting theorem for rotating gravito-electromagnetic systems. The variational method is then applied to clarify the working mechanism of particular devices.

Holocene glacier fluctuations inferred from lacustrine sediment, Emerald Lake, Kenai Peninsula, Alaska

Science.gov (United States)

LaBrecque, Taylor S.; Kaufman, Darrell S.

2016-01-01

Physical and biological characteristics of lacustrine sediment from Emerald Lake were used to reconstruct the Holocene glacier history of Grewingk Glacier, southern Alaska. Emerald Lake is an ice-marginal threshold lake, receiving glaciofluvial sediment when Grewingk Glacier overtops the topographic divide that separates it from the lake. Sub-bottom acoustical profiles were used to locate core sites to maximize both the length and resolution of the sedimentary sequence recovered in the 4-m-long cores. The age model for the composite sequence is based on 13 14C ages and a 210Pb profile. A sharp transition from the basal inorganic mud to organic-rich mud at 11.4 ± 0.2 ka marks the initial retreat of Grewingk Glacier below the divide of Emerald Lake. The overlaying organic-rich mud is interrupted by stony mud that records a re-advance between 10.7 ± 0.2 and 9.8 ± 0.2 ka. The glacier did not spill meltwater into the lake again until the Little Ice Age, consistent with previously documented Little Ice Ages advances on the Kenai Peninsula. The retreat of Grewingk Glacier at 11.4 ka took place as temperature increased following the Younger Dryas, and the subsequent re-advance corresponds with a climate reversal beginning around 11 ka across southern Alaska.

Sedimentology and Reservoir Characteristics of Early Cretaceous Fluvio-Deltaic and Lacustrine Deposits, Upper Abu Gabra Formation, Sufyan Sub-basin, Muglad Rift Basin, Sudan

Science.gov (United States)

Yassin, Mohamed; Abdullatif, Osman; Hariri, Mustafa

2017-04-01

Sufyan Sub-basin is an East-West trending Sub-basin located in the northwestern part of the Muglad Basin (Sudan), in the eastern extension of the West and Central Africa Rift System (WCARS). The Early Cretaceous Abu Gabra Formation considered as the main source rock in the Muglad Basin. In Sufyan Sub-basin the Early Cretaceous Upper Abu Gabra Formation is the main oil-producing reservoir. It is dominated by sandstone and shales deposited in fluvio-deltaic and lacustrine environment during the first rift cycle in the basin. Depositional and post-depositional processes highly influenced the reservoir quality and architecture. This study investigates different scales of reservoir heterogeneities from macro to micro scale. Subsurface facies analysis was analyzed based on the description of six conventional cores from two wells. Approaches include well log analysis, thin sections and scanning electron microscope (SEM) investigations, grain-size, and X-ray diffraction (XRD) analysis of the Abu Gabra sandstone. The cores and well logs analyses revealed six lithofacies representing fluvio-deltaic and lacustrine depositional environment. The sandstone is medium to coarse-grained, poorly to moderately sorted and sub-angular to subrounded, Sub-feldspathic arenite to quartz arenite. On macro-scale, reservoir quality varies within Abu Gabra reservoir where it shows progressive coarsening upward tendencies with different degrees of connectivity. The upper part of the reservoir showed well connected and amalgamated sandstone bodies, the middle to lower parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenesis.The XRD and SEM analyses show that kaolinite and chlorite clay are the common clay minerals in the studied samples. Clay matrix and quartz overgrowth have significantly reduced the reservoir porosity and permeability, while the dissolution of feldspars

Concepts, Operations, and Feasibility of a Projection-Based Variation Control System

DEFF Research Database (Denmark)

Stanciulescu, Stefan; Berger, Thorsten; Walkingshaw, Eric

2016-01-01

on a subset of all variants could ease the engineering of highly configurable software. We investigate the potential of one kind of such tools: projection-based variation control systems. For such systems we aim to understand: (i) what end-user operations they need to support, and (ii) whether they can...... realize the actual evolution of real-world, highly configurable software. We conduct an experiment that investigates variability-related evolution patterns and that evaluates the feasibility of a projection-based variation control system by replaying parts of the history of a highly configurable real......Highly configurable software often uses preproces- sor annotations to handle variability. However, understanding, maintaining, and evolving code with such annotations is difficult, mainly because a developer has to work with all variants at a time. Dedicated methods and tools that allow working...

Analysis of arsenic speciation in mine contaminated lacustrine sediment using selective sequential extraction, HR-ICPMS and TEM

International Nuclear Information System (INIS)

Haus, Kelly L.; Hooper, Robert L.; Strumness, Laura A.; Mahoney, J. Brian

2008-01-01

In order to determine how As speciation in lacustrine sediment changes as a function of local conditions, sediment cores were taken from three lakes with differing hydrologic regimes and subjected to extensive chemical and TEM analysis. The lakes (Killarney, Thompson and Swan Lakes) are located within the Coeur d' Alene River system (northern Idaho, USA), which has been contaminated with trace metals and As, from over 100 a of sulfide mining. Previous analyses of these lakebed sediments have shown an extensive amount of contaminant metals and As associated with sub-μm grains, making them extremely difficult to analyze using standard methods (scanning electron microscopy, X-ray diffraction). Transmission electron microscopy offers great advantages in spatial resolution and can be invaluable in determining As speciation when combined with other techniques. Data indicate that because of differences in local redox conditions, As speciation and stability is dramatically different in these lakes. Killarney and Thompson Lakes experience seasonal water-level fluctuations due to drawdown on a downstream dam, causing changes in O 2 content in sediment exposed during drawdown. Swan Lake has relatively constant water levels as its only inlet is dammed. Consequently, Killarney and Thompson Lakes show an increase in labile As-bearing phases with depth, while Swan Lake data indicate stable As hosts throughout the sediment profile. Based on these observations it can be stated that As in lakebed sediments is much less mobile, and therefore less bioavailable, when water is kept at a constant level

Holocene glacier variations and sea level change in Wahlenbergfjorden, Nordaustlandet, Svalbard

Science.gov (United States)

Schomacker, A.; Farnsworth, W. R.; Ingolfsson, O.; Allaart, L.; Håkansson, L.; Retelle, M.

2017-12-01

Here we present preliminary results on the Holocene glacier variations in Wahlenbergfjorden on Nordaustlandet, Svalbard. The reconstructions are based on lake sediment records from Lake Kl\\overbladvatna covering the last 9500 years. This lake captures meltwater from the Etonbreen glacier, a main outlet of the Austfonna ice cap, when the glacier extends further than present. Additionally, Kl\\overbladvatna is an isolation basin capturing the postglacial isolation from the marine to lacustrine environment due to glacioisostatic rebound. The chronology is based on radiocarbon dating of terrestrial and marine macrofossils. The lake sediment record also reveals that glacial meltwater exceeded the threshold into Lake Kl\\overbladvatna during the Little Ice Age as witnessed by glacial meltwater clay in the upper part of the sediment cores. In periods of less advanced glaciers, the lake sediment record is dominated by laminated clayey gyttja. Based on radiocarbon datings of driftwood, whalebone, and marine mollusc shells in raised beaches and marine deposits in Pallanderbukta, south Wahlenbergfjorden, we also present a new postglacial sea level curve from this region.

Behavior of diatomaceous soil in lacustrine deposits of Bogotá, Colombia

Directory of Open Access Journals (Sweden)

Bernardo Caicedo

2018-04-01

Full Text Available This work presents a study on the behaviors of diatomaceous soils. Although studies are rarely reported on these soils, they have been identified in Mexico City, the Sea of Japan, the northeast coast of Australia, the equatorial Pacific, and the lacustrine deposit of Bogotá (Colombia, among other locations. Features of this kind of soil include high friction angle, high initial void ratio, high compressibility index, high liquid limit, and low density. Some of these features are counterintuitive from a classical soil mechanics viewpoint. To understand the geotechnical properties of the diatomaceous soil, a comprehensive experimental plan consisting of more than 2400 tests was performed, including physical tests such as grain size distribution, Atterberg limits, density of solid particles, and organic matter content; and mechanical tests such as oedometric compression tests, unconfined compression tests, and triaxial tests. Laboratory tests were complemented with scanning electron microscope (SEM observations to evaluate the microstructure of the soil. The test results show that there is an increase in liquid limit with increasing diatomaceous content, and the friction angle also increases with increasing diatomaceous content. In addition, several practical correlations were proposed for this soil type for shear strength mobilization and intrinsic compression line. Finally, useful correlations were presented, such as the relationship between the state consistency and the undrained shear strength, the friction angle and the liquid limit, the void ratio at 100 kPa and the liquid limit, the plasticity index and the diatomaceous content, among others. Keywords: Diatomaceous soil, Soft soils, Compressibility, Friction angle, Natural soil

Equatorial Precession Drove Mid-Latitude Changes in ENSO-Scale Variation in the Earliest Miocene

Science.gov (United States)

Fox, B.; D'Andrea, W. J.; Lee, D. E.; Wilson, G. S.

2014-12-01

Foulden Maar is an annually laminated lacustrine diatomite deposit from the South Island of New Zealand. The deposit was laid down over ~100 kyr of the latest Oligocene and earliest Miocene, during the peak and deglaciation phase of the Mi-1 Antarctic glaciation event. At this time, New Zealand was located at approximately the same latitude as today (~45°S). Evidence from organic geochemical proxies (δD, δ13C) and physical properties (density, colour) indicates the presence of an 11-kyr cycle at the site. Although it is known that 11-kyr insolation (half-precession) cycles occur between the Tropics, this cycle is rarely seen in sedimentary archives deposited outside the immediate vicinity of the Equator. Records from Foulden Maar correlate well with the amplitude and phase of the modelled equatorial half-precession cycle for the earliest Miocene. High-resolution (50 µm) colour intensity measurements and lamina thickness measurements both indicate the presence of significant ENSO-like (2-8 year) variation in the Foulden Maar sediments. Early results from targeted lamina thickness measurements suggest that ENSO-band variation is modulated by the 11-kyr cycle, with power in the ENSO band increasing during periods of increased insolation at the Equator. This implies that equatorial half-precession had a significant effect on ENSO-like variation in the early Miocene, and that this effect was felt as far afield as the mid-latitudes of the Southern Hemisphere.

Evidences of melting of terrestrial sediments and paleoenvironment changes during the Younger Dryas in tectonic lacustrine basins of Transmexican Volcanic Belt, Mexico.

Science.gov (United States)

Israde-Alcantara, I.

2017-12-01

It is well known in the sedimentary record of several parts of the world that during the Younger Dryas interval (YD) ocurred an abrupt environmental change between 12,900 and 11,700 cal yr BP (10,900 to 10,000 14C BP). In the lacustrine basins this changes are often preserved and in some Mexican lakes this is a distinctive stratigraphic marker for the YD. We analized the proxies of this event in cores of two lakes (Chapala, Cuitzeo) and three trenches of ex-lakes (Acambay,Texcoco and El Cedral). Deposits consist of fine detrital material with often Pleistocene fossil vertebrate assemblages. At the Chapala, Cuitzeo, Acambay, and Tocuila lacustrine environments are found in association with a distinctive dark organic layer showing sharp changes in the diatom, pollen, mineralogical and geochemical record. Includes also microscopic magnetic, Fe-rich spherules, silica melted droplets with aerodynamic shapes (tektites), followed by large amounts of charcoal, and sometimes nanodiamonds (Cuitzeo), that were deposited at the onset of the YD or in the limit Pleistocene-Holocene. These unusual materials are buried more than 2.50 meters and were not observed above or below the Younger Dryas sediments at these sites. The geochemistry of the microspherules indicates that they are not volcanic, anthropogenic or authigenic origin. A very distinctive feature is the shape of the spherules, ovoid, polygonal, filigreed or dendritic indicating melting and quenching infering that are product of an impact event. Their morphologies includes hollow shells caused by de-gassing of elements at very high temperatures causing a flattened side with a "skirt" structure by a high-velocity collision.Our results are consistent with the Firestone hypothesis.

Variation in the Breeding System of Prunella vulgaris L.

Science.gov (United States)

Qu, Luping; Widrlechner, Mark P

2011-05-01

Prunella vulgaris (Lamiaceae), commonly known as selfheal, is a perennial herb with a long history of use in traditional medicine. Recent studies have found that P. vulgaris possesses anti-inflammatory, antiviral, and antibacterial properties, and it is likely that this will lead to increased commercial demand for this species. To date, research publications on P. vulgaris cultivation and genetics are scarce. Using accessions originally collected from different geographical regions, we investigated the breeding system of this species by observing variation in floral morphology, time of pollen release, and selfed-seed set in bagged flowers and isolated plants. Two types of floral morphology, one with exerted styles, extending past open corollas when viewed from above, and the other with shorter, inserted styles, were found among 30 accessions. Two accessions originally collected from Asia uniformly displayed exerted styles, and 27 accessions had inserted styles. One accession from Oregon displayed variation in this trait among individual plants. Microscopic observation of seven accessions, including ones with both exerted and inserted styles, revealed that they all release pollen to some degree before the flowers open. Using bagged flowers, we found that selfed-seed set varied widely among eight accessions, ranging from 6% to 94%. However, bagging may underestimate seed set for some accessions. The two accessions with the lowest rates when using bagged flowers increased in seed set by 350% and 158%, respectively, when we evaluated single, unbagged plants in isolation cages. The accession with 6% selfed-seed set when bagged also had exerted styles. These findings suggest that mating systems in P. vulgaris may be in the process of evolutionary change and that understanding breeding-system variation should be useful in developing efficient seed-regeneration protocols and breeding and selection strategies for this species.

Orbital Period Variations in the NY Vir System, Revisited in the Light of New Data

Directory of Open Access Journals (Sweden)

Baştürk Özgür

2018-02-01

Full Text Available NY Virginis is an eclipsing binary system with a subdwarf B primary and an M type dwarf secondary. Recent studies (Qian et al. 2012; Lee et al. 2014 suggested the presence of two circumbinary planets with a few Jovian masses within the system. Lee et al. (2014 examined the orbital stabilities of the suggested planets, using the best-fit parameters derived from their eclipse timing variation analysis. They found that the outer companion should be ejected from the system in about 800 000 years. An observational report from Pulley et al. (2016 pointed out that the recent mideclipse times of the binary deviate significantly from the models suggested by Lee et al. (2014. In fact, variations in the orbital period of the system had already been recognized by many authors, but the parameters of these variations vary significantly as new data accumulate. Here, we analyze the eclipse timing variations of the NY Vir system, using new mid-eclipse times that we have obtained together with earlier published measurements in order to understand the nature of the system and constrain its parameters.

Stratigraphy and Facies Analysis of a 122 M Long Lacustrine Sequence from Chalco Lake, Central Mexico

Science.gov (United States)

Herrera, D. A.; Ortega, B.; Caballero, M.; Lozano, S.; Pi, T.; Brown, E. T.

2010-12-01

Chalco lake is located SE of the outskirts of Mexico City, at the central part of the Trans Mexican Volcanic Belt. Previous studies show the importance of this lacustrine sequence as an archive of paleoenvironmental and paleoclimatic changes. A set of five cores up to 122 m depth were drilled in the basin, in order to analyze the sedimentary record and to extent the previous knowledge of past environmental changes in central Mexico. As an initial step, in this work we present the identification and classification of sedimentary facies. Preliminary paleomagnetism analyses recognize the possible record of the Blake Event (ca. 120 kyr BP), and suggest that the sequence might span the last 240 kyr. In this case, variations in sedimentary facies could reflect the conditions of the MIS 1-7. The facies are mostly diatom ooze, carbonate mud, organic rich silt and volcaniclastic, both massive and laminated, and massive dark gray to reddish brown silt. From 1 to 8 m depth dominates the organic rich silt facies, which correlates with the MIS 1. Intercalations of reddish brown and grayish brown silt facies, between 8 to 60 m depth, indicate changes occurred during MIS 2 to 5d. Between 60-75 m depth the sequence is characterized by dark grayish silty clay facies, which possibly coincide with the MIS 5e. At 79 m depth (ca. 130 kyr BP) we found struvite (MgNH4PO4.6H2O), which may be related to dry conditions. The laminated diatom ooze facies dominates between 90 to 122 m depth and indicates rhythmic changes in the sediment deposition of the basin. The volcaniclastic facies is represented by lapilli and ash deposits in more than 100 individual tephra layers of both mafic and felsic composition. Some of them correspond to main volcanic eruptions, as the Upper Toluca Pumice (13,500 cal yr BP), from the Nevado de Toluca volcano and the Pómez con Andesita (17,700 cal yr BP) from the Popocatépetl volcano. The carbonate mud facies is composed of calcite and siderite, with frequent

The Semianalytical Solutions for Stiff Systems of Ordinary Differential Equations by Using Variational Iteration Method and Modified Variational Iteration Method with Comparison to Exact Solutions

Directory of Open Access Journals (Sweden)

Mehmet Tarik Atay

2013-01-01

Full Text Available The Variational Iteration Method (VIM and Modified Variational Iteration Method (MVIM are used to find solutions of systems of stiff ordinary differential equations for both linear and nonlinear problems. Some examples are given to illustrate the accuracy and effectiveness of these methods. We compare our results with exact results. In some studies related to stiff ordinary differential equations, problems were solved by Adomian Decomposition Method and VIM and Homotopy Perturbation Method. Comparisons with exact solutions reveal that the Variational Iteration Method (VIM and the Modified Variational Iteration Method (MVIM are easier to implement. In fact, these methods are promising methods for various systems of linear and nonlinear stiff ordinary differential equations. Furthermore, VIM, or in some cases MVIM, is giving exact solutions in linear cases and very satisfactory solutions when compared to exact solutions for nonlinear cases depending on the stiffness ratio of the stiff system to be solved.

Hedgehog signaling mediates adaptive variation in a dynamic functional system in the cichlid feeding apparatus.

Science.gov (United States)

Hu, Yinan; Albertson, R Craig

2014-06-10

Adaptive variation in the craniofacial skeleton is a key component of resource specialization and habitat divergence in vertebrates, but the proximate genetic mechanisms that underlie complex patterns of craniofacial variation are largely unknown. Here we demonstrate that the Hedgehog (Hh) signaling pathway mediates widespread variation across a complex functional system that affects the kinematics of lower jaw depression--the opercular four-bar linkage apparatus--among Lake Malawi cichlids. By using a combined quantitative trait locus mapping and population genetics approach, we show that allelic variation in the Hh receptor, ptch1, affects the development of distinct bony elements in the head that represent two of three movable links in this functional system. The evolutionarily derived allele is found in species that feed from the water column, and is associated with shifts in anatomy that translate to a four-bar system capable of faster jaw rotation. Alternatively, the ancestral allele is found in species that feed on attached algae, and is associated with the development of a four-bar system that predicts slower jaw movement. Experimental manipulation of the Hh pathway during cichlid development recapitulates functionally salient natural variation in craniofacial geometry. In all, these results significantly extend our understanding of the mechanisms that fine-tune the craniofacial skeletal complex during adaptation to new foraging niches.

Variational and penalization methods for studying connecting orbits of Hamiltonian systems

Directory of Open Access Journals (Sweden)

Chao-Nien Chen

2000-08-01

Full Text Available In this article, we consider a class of second order Hamiltonian systems that possess infinite or finite number of equilibria. Variational arguments will be used to study the existence of connecting orbits joining pairs of equilibria. Applying penalization methods, we obtain various patterns for multibump homoclinics and heteroclinics of Hamiltonian systems.

Variational and quasi-variational inequalities in mechanics

CERN Document Server

Kravchuk, Alexander S

2007-01-01

The essential aim of the present book is to consider a wide set of problems arising in the mathematical modelling of mechanical systems under unilateral constraints. In these investigations elastic and non-elastic deformations, friction and adhesion phenomena are taken into account. All the necessary mathematical tools are given: local boundary value problem formulations, construction of variational equations and inequalities, and the transition to minimization problems, existence and uniqueness theorems, and variational transformations (Friedrichs and Young-Fenchel-Moreau) to dual and saddle-point search problems. Important new results concern contact problems with friction. The Coulomb friction law and some others are considered, in which relative sliding velocities appear. The corresponding quasi-variational inequality is constructed, as well as the appropriate iterative method for its solution. Outlines of the variational approach to non-stationary and dissipative systems and to the construction of the go...

Analysis of arsenic speciation in mine contaminated lacustrine sediment using selective sequential extraction, HR-ICPMS and TEM

Energy Technology Data Exchange (ETDEWEB)

Haus, Kelly L. [Department of Geology, Phillips 157, University of Wisconsin - Eau Claire, Eau Claire, WI 54702-4004 (United States)], E-mail: khaus@vt.edu; Hooper, Robert L.; Strumness, Laura A.; Mahoney, J. Brian [Department of Geology, Phillips 157, University of Wisconsin - Eau Claire, Eau Claire, WI 54702-4004 (United States)

2008-04-15

In order to determine how As speciation in lacustrine sediment changes as a function of local conditions, sediment cores were taken from three lakes with differing hydrologic regimes and subjected to extensive chemical and TEM analysis. The lakes (Killarney, Thompson and Swan Lakes) are located within the Coeur d' Alene River system (northern Idaho, USA), which has been contaminated with trace metals and As, from over 100 a of sulfide mining. Previous analyses of these lakebed sediments have shown an extensive amount of contaminant metals and As associated with sub-{mu}m grains, making them extremely difficult to analyze using standard methods (scanning electron microscopy, X-ray diffraction). Transmission electron microscopy offers great advantages in spatial resolution and can be invaluable in determining As speciation when combined with other techniques. Data indicate that because of differences in local redox conditions, As speciation and stability is dramatically different in these lakes. Killarney and Thompson Lakes experience seasonal water-level fluctuations due to drawdown on a downstream dam, causing changes in O{sub 2} content in sediment exposed during drawdown. Swan Lake has relatively constant water levels as its only inlet is dammed. Consequently, Killarney and Thompson Lakes show an increase in labile As-bearing phases with depth, while Swan Lake data indicate stable As hosts throughout the sediment profile. Based on these observations it can be stated that As in lakebed sediments is much less mobile, and therefore less bioavailable, when water is kept at a constant level.

A variational integrators approach to second order modeling and identification of linear mechanical systems

NARCIS (Netherlands)

Bruschetta, M.; Saccon, A.; Picci, G.

2014-01-01

The theory of variational integration provides a systematic procedure to discretize the equations of motion of a mechanical system, preserving key properties of the continuous time flow. The discrete-time model obtained by variational integration theory inherits structural conditions which in

Variational submanifolds of Euclidean spaces

Science.gov (United States)

Krupka, D.; Urban, Z.; Volná, J.

2018-03-01

Systems of ordinary differential equations (or dynamical forms in Lagrangian mechanics), induced by embeddings of smooth fibered manifolds over one-dimensional basis, are considered in the class of variational equations. For a given non-variational system, conditions assuring variationality (the Helmholtz conditions) of the induced system with respect to a submanifold of a Euclidean space are studied, and the problem of existence of these "variational submanifolds" is formulated in general and solved for second-order systems. The variational sequence theory on sheaves of differential forms is employed as a main tool for the analysis of local and global aspects (variationality and variational triviality). The theory is illustrated by examples of holonomic constraints (submanifolds of a configuration Euclidean space) which are variational submanifolds in geometry and mechanics.

Convex Minimization with Constraints of Systems of Variational Inequalities, Mixed Equilibrium, Variational Inequality, and Fixed Point Problems

Directory of Open Access Journals (Sweden)

Lu-Chuan Ceng

2014-01-01

Full Text Available We introduce and analyze one iterative algorithm by hybrid shrinking projection method for finding a solution of the minimization problem for a convex and continuously Fréchet differentiable functional, with constraints of several problems: finitely many generalized mixed equilibrium problems, finitely many variational inequalities, the general system of variational inequalities and the fixed point problem of an asymptotically strict pseudocontractive mapping in the intermediate sense in a real Hilbert space. We prove strong convergence theorem for the iterative algorithm under suitable conditions. On the other hand, we also propose another iterative algorithm by hybrid shrinking projection method for finding a fixed point of infinitely many nonexpansive mappings with the same constraints, and derive its strong convergence under mild assumptions.

Low complexity variational bayes iterative reviver for MIMO-OFDM systems

DEFF Research Database (Denmark)

Xiong, Chunlin; Wang, Hua; Zhang, Xiaoying

2009-01-01

A low complexity iterative receiver is proposed in this paper for MIMO-OFDM systems in time-varying multi-path channel based on the variational Bayes (VB) method. According to the VB method, the estimation algorithms of the signal distribution and the channel distribution are derived for the rece...

Variationally optimal selection of slow coordinates and reaction coordinates in macromolecular systems

Science.gov (United States)

Noe, Frank

To efficiently simulate and generate understanding from simulations of complex macromolecular systems, the concept of slow collective coordinates or reaction coordinates is of fundamental importance. Here we will introduce variational approaches to approximate the slow coordinates and the reaction coordinates between selected end-states given MD simulations of the macromolecular system and a (possibly large) basis set of candidate coordinates. We will then discuss how to select physically intuitive order paremeters that are good surrogates of this variationally optimal result. These result can be used in order to construct Markov state models or other models of the stationary and kinetics properties, in order to parametrize low-dimensional / coarse-grained model of the dynamics. Deutsche Forschungsgemeinschaft, European Research Council.

Anatomical variations of hepatic arterial system, coeliac trunk and renal arteries: an analysis with multidetector CT angiography.

Science.gov (United States)

Ugurel, M S; Battal, B; Bozlar, U; Nural, M S; Tasar, M; Ors, F; Saglam, M; Karademir, I

2010-08-01

The purpose of our investigation was to determine the anatomical variations in the coeliac trunk-hepatic arterial system and the renal arteries in patients who underwent multidetector CT (MDCT) angiography of the abdominal aorta for various reasons. A total of 100 patients were analysed retrospectively. The coeliac trunk, hepatic arterial system and renal arteries were analysed individually and anatomical variations were recorded. Statistical analysis of the relationship between hepatocoeliac variations and renal artery variations was performed using a chi(2) test. There was a coeliac trunk trifurcation in 89% and bifurcation in 8% of the cases. Coeliac trunk was absent in 1%, a hepatosplenomesenteric trunk was seen in 1% and a splenomesenteric trunk was present in 1%. Hepatic artery variation was present in 48% of patients. Coeliac trunk and/or hepatic arterial variation was present in 23 (39.7%) of the 58 patients with normal renal arteries, and in 27 (64.3%) of the 42 patients with accessory renal arteries. There was a statistically significant correlation between renal artery variations and coeliac trunk-hepatic arterial system variations (p = 0.015). MDCT angiography permits a correct and detailed evaluation of hepatic and renal vascular anatomy. The prevalence of variations in the coeliac trunk and/or hepatic arteries is increased in people with accessory renal arteries. For that reason, when undertaking angiographic examinations directed towards any single organ, the possibility of variations in the vascular structure of other organs should be kept in mind.

Meteorological Research Institute multivariate ocean variational estimation (MOVE) system: Some early results

Science.gov (United States)

Usui, Norihisa; Ishizaki, Shiro; Fujii, Yosuke; Tsujino, Hiroyuki; Yasuda, Tamaki; Kamachi, Masafumi

The Meteorological Research Institute multivariate ocean variational estimation (MOVE) System has been developed as the next-generation ocean data assimilation system in Japan Meteorological Agency. A multivariate three-dimensional variational (3DVAR) analysis scheme with vertical coupled temperature salinity empirical orthogonal function modes is adopted. The MOVE system has two varieties, the global (MOVE-G) and North Pacific (MOVE-NP) systems. The equatorial Pacific and western North Pacific are analyzed with assimilation experiments using MOVE-G and -NP, respectively. In each system, the salinity and velocity fields are well reproduced, even in cases without salinity data. Changes in surface and subsurface zonal currents during the 1997/98 El Niño event are captured well, and their transports are reasonably consistent with in situ observations. For example, the eastward transport in the upper layer around the equator has 70 Sv in spring 1997 and weakens in spring 1998. With MOVE-NP, the Kuroshio transport has 25 Sv in the East China Sea, and 40 Sv crossing the ASUKA (Affiliated Surveys of the Kuroshio off Cape Ashizuri) line south of Japan. The variations in the Kuroshio transports crossing the ASUKA line agree well with observations. The Ryukyu Current System has a transport ranging from 6 Sv east of Taiwan to 17 Sv east of Amami. The Oyashio transport crossing the OICE (Oyashio Intensive observation line off Cape Erimo) line south of Hokkaido has 14 Sv southwestward (near shore) and 11 Sv northeastward (offshore). In the Kuroshio Oyashio transition area east of Japan, the eastward transport has 41 Sv (32 36°N) and 12 Sv (36 39°N) crossing the 145°E line.

AMOC variations in 1979-2008 simulated by NCEP operational ocean data assimilation system

Energy Technology Data Exchange (ETDEWEB)

Huang, Boyin [Climate Prediction Center, NOAA, Camp Springs, MD (United States); National Climate Data Center, Asheville, NC (United States); Xue, Yan; Kumar, Arun [Climate Prediction Center, NOAA, Camp Springs, MD (United States); Behringer, David W. [Environmental Modeling Center, NOAA, Camp Springs, MD (United States)

2012-02-15

Variations in the Atlantic meridional overturning circulation (AMOC) between 1979 and 2008 are documented using the operational ocean analysis, the Global Ocean Data Assimilation System (GODAS), at the National Centers for Climate Prediction (NCEP). The maximum AMOC at 40 N is about 16 Sv in average with peak-to-peak variability of 3-4 Sv. The AMOC variations are dominated by an upward trend from 1980 to 1995, and a downward trend from 1995 to 2008. The maximum AMOC at 26.5 N is slightly weaker than hydrographic estimates and observations from mooring array. The dominant variability of the AMOC in 20 -65 N (the first EOF, 51% variance) is highly correlated with that in the subsurface temperature (the first EOF, 33% variance), and therefore, with density (the first EOF, 25% variance) in the North Atlantic, and is consistent with the observational estimates based on the World Ocean Database 2005. The dominant variabilities of AMOC and subsurface temperature are also analyzed in the context of possible links with the net surface heat flux, deep convection, western boundary current, and subpolar gyre. Variation in the net surface heat flux is further linked to the North Atlantic Oscillation (NAO) index which is found to lead AMOC variations by about 5 years. Our results indicate that AMOC variations can be documented based on an ocean analysis system such as GODAS. (orig.)

Path-space variational inference for non-equilibrium coarse-grained systems

International Nuclear Information System (INIS)

Harmandaris, Vagelis; Kalligiannaki, Evangelia; Katsoulakis, Markos; Plecháč, Petr

2016-01-01

In this paper we discuss information-theoretic tools for obtaining optimized coarse-grained molecular models for both equilibrium and non-equilibrium molecular simulations. The latter are ubiquitous in physicochemical and biological applications, where they are typically associated with coupling mechanisms, multi-physics and/or boundary conditions. In general the non-equilibrium steady states are not known explicitly as they do not necessarily have a Gibbs structure. The presented approach can compare microscopic behavior of molecular systems to parametric and non-parametric coarse-grained models using the relative entropy between distributions on the path space and setting up a corresponding path-space variational inference problem. The methods can become entirely data-driven when the microscopic dynamics are replaced with corresponding correlated data in the form of time series. Furthermore, we present connections and generalizations of force matching methods in coarse-graining with path-space information methods. We demonstrate the enhanced transferability of information-based parameterizations to different observables, at a specific thermodynamic point, due to information inequalities. We discuss methodological connections between information-based coarse-graining of molecular systems and variational inference methods primarily developed in the machine learning community. However, we note that the work presented here addresses variational inference for correlated time series due to the focus on dynamics. The applicability of the proposed methods is demonstrated on high-dimensional stochastic processes given by overdamped and driven Langevin dynamics of interacting particles.

Path-space variational inference for non-equilibrium coarse-grained systems

Energy Technology Data Exchange (ETDEWEB)

Harmandaris, Vagelis, E-mail: harman@uoc.gr [Department of Mathematics and Applied Mathematics, University of Crete (Greece); Institute of Applied and Computational Mathematics (IACM), Foundation for Research and Technology Hellas (FORTH), IACM/FORTH, GR-71110 Heraklion (Greece); Kalligiannaki, Evangelia, E-mail: ekalligian@tem.uoc.gr [Department of Mathematics and Applied Mathematics, University of Crete (Greece); Katsoulakis, Markos, E-mail: markos@math.umass.edu [Department of Mathematics and Statistics, University of Massachusetts at Amherst (United States); Plecháč, Petr, E-mail: plechac@math.udel.edu [Department of Mathematical Sciences, University of Delaware, Newark, Delaware (United States)

2016-06-01

In this paper we discuss information-theoretic tools for obtaining optimized coarse-grained molecular models for both equilibrium and non-equilibrium molecular simulations. The latter are ubiquitous in physicochemical and biological applications, where they are typically associated with coupling mechanisms, multi-physics and/or boundary conditions. In general the non-equilibrium steady states are not known explicitly as they do not necessarily have a Gibbs structure. The presented approach can compare microscopic behavior of molecular systems to parametric and non-parametric coarse-grained models using the relative entropy between distributions on the path space and setting up a corresponding path-space variational inference problem. The methods can become entirely data-driven when the microscopic dynamics are replaced with corresponding correlated data in the form of time series. Furthermore, we present connections and generalizations of force matching methods in coarse-graining with path-space information methods. We demonstrate the enhanced transferability of information-based parameterizations to different observables, at a specific thermodynamic point, due to information inequalities. We discuss methodological connections between information-based coarse-graining of molecular systems and variational inference methods primarily developed in the machine learning community. However, we note that the work presented here addresses variational inference for correlated time series due to the focus on dynamics. The applicability of the proposed methods is demonstrated on high-dimensional stochastic processes given by overdamped and driven Langevin dynamics of interacting particles.

Is variation management included in regional healthcare governance systems? Some proposals from Italy.

Science.gov (United States)

Nuti, Sabina; Seghieri, Chiara

2014-01-01

The Italian National Health System, which follows a Beveridge model, provides universal healthcare coverage through general taxation. Universal coverage provides uniform healthcare access to citizens and is the characteristic usually considered the added value of a welfare system financed by tax revenues. Nonetheless, wide differences in practice patterns, health outcomes and regional usages of resources that cannot be justified by differences in patient needs have been demonstrated to exist. Beginning with the experience of the health care system of the Tuscany region (Italy), this study describes the first steps of a long-term approach to proactively address the issue of geographic variation in healthcare. In particular, the study highlights how the unwarranted variation management has been addressed in a region with a high degree of managerial control over the delivery of health care and a consolidated performance evaluation system, by first, considering it a high priority objective and then by actively integrating it into the regional planning and control mechanism. The implications of this study can be useful to policy makers, professionals and managers, and will contribute to the understanding of how the management of variation can be implemented with performance measurements and financial incentives. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Petroleum systems of the Malay Basin Province, Malaysia

Science.gov (United States)

Bishop, Michele G.

2002-01-01

The offshore Malay Basin province is a Tertiary oil and gas province composed of a complex of half grabens that were filled by lacustrine shales and continental clastics.These deposits were overlain by clastics of a large delta system that covered the basin.Delta progradation was interupted by transgressions of the South China Sea to the southeast, which finally flooded the basin to form the Gulf of Thailand.Oil and gas from the Oligocene to Miocene lacustrine shales and Miocene deltaic coals is trapped primarily in anticlines formed by inversion of the half grabens during the late Miocene.Hydrocarbon reserves that have been discovered amount to 12 billion barrels of oil equivalent.The U.S. Geological Survey assessment of the estimated quantities of conventional oil, gas and condensate that have the potential to be added to reserves by the year 2025 for this province is 6.3 billion barrels of oil equivalent (BBOE) (U. S. Geological Survey World Energy Assessment Team, 2000).

Structured approaches to large-scale systems: Variational integrators for interconnected Lagrange-Dirac systems and structured model reduction on Lie groups

Science.gov (United States)

Parks, Helen Frances

This dissertation presents two projects related to the structured integration of large-scale mechanical systems. Structured integration uses the considerable differential geometric structure inherent in mechanical motion to inform the design of numerical integration schemes. This process improves the qualitative properties of simulations and becomes especially valuable as a measure of accuracy over long time simulations in which traditional Gronwall accuracy estimates lose their meaning. Often, structured integration schemes replicate continuous symmetries and their associated conservation laws at the discrete level. Such is the case for variational integrators, which discretely replicate the process of deriving equations of motion from variational principles. This results in the conservation of momenta associated to symmetries in the discrete system and conservation of a symplectic form when applicable. In the case of Lagrange-Dirac systems, variational integrators preserve a discrete analogue of the Dirac structure preserved in the continuous flow. In the first project of this thesis, we extend Dirac variational integrators to accommodate interconnected systems. We hope this work will find use in the fields of control, where a controlled system can be thought of as a "plant" system joined to its controller, and in the approach of very large systems, where modular modeling may prove easier than monolithically modeling the entire system. The second project of the thesis considers a different approach to large systems. Given a detailed model of the full system, can we reduce it to a more computationally efficient model without losing essential geometric structures in the system? Asked without the reference to structure, this is the essential question of the field of model reduction. The answer there has been a resounding yes, with Principal Orthogonal Decomposition (POD) with snapshots rising as one of the most successful methods. Our project builds on previous work

Applications of exterior difference systems to variations in discrete mechanics

International Nuclear Information System (INIS)

Xie Zheng; Li Hongbo

2008-01-01

In discrete mechanics, difference equations describe the fundamental physical laws and exhibit many geometric properties. Can these equations be obtained in a geometric way? Using some techniques in exterior difference systems, we investigate the discrete variational problem. As an application, we give a positive answer to the above question for the discrete Newton's, Euler-Lagrange, and Hamilton's equations

Sedimentology, sequence-stratigraphy, and geochemical variations in the Mesoproterozoic Nonesuch Formation, northern Wisconsin, USA

Science.gov (United States)

Kingsbury Stewart, Esther; Mauk, Jeffrey L.

2017-01-01

We use core descriptions and portable X-ray fluorescence analyses to identify lithofacies and stratigraphic surfaces for the Mesoproterozoic Nonesuch Formation within the Ashland syncline, Wisconsin. We group lithofacies into facies associations and construct a sequence stratigraphic framework based on lithofacies stacking and stratigraphic surfaces. The fluvial-alluvial facies association (upper Copper Harbor Conglomerate) is overlain across a transgressive surface by the fluctuating-profundal facies association (lower Nonesuch Formation). The fluctuating-profundal facies association comprises a retrogradational sequence set overlain across a maximum flooding surface by an aggradational-progradational sequence set comprising fluctuating-profundal, fluvial-lacustrine, and fluvial-alluvial facies associations (middle Nonesuch through lower Freda Formations). Lithogeochemistry supports sedimentologic and stratigraphic interpretations. Fe/S molar ratios reflect the oxidation state of the lithofacies; values are most depleted above the maximum flooding surface where lithofacies are chemically reduced and are greatest in the chemically oxidized lithofacies. Si/Al and Zr/Al molar ratios reflect the relative abundance of detrital heavy minerals vs. clay minerals; greater values correlate with larger grain size. Vertical facies association stacking records depositional environments that evolved from fluvial and alluvial, to balanced-fill lake, to overfilled lake, and returning to fluvial and alluvial. Elsewhere in the basin, where accommodation was greatest, some volume of fluvial-lacustrine facies is likely present below the transgressive stratigraphic surface. This succession of continental and lake-basin types indicates a predominant tectonic driver of basin evolution. Lithofacies distribution and geochemistry indicate deposition within an asymmetric half-graben bounded on the east by a west-dipping growth fault. While facies assemblages are lacustrine and continental

Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru.

Science.gov (United States)

Patterson, R Timothy; Huckerby, Gail; Kelly, Thomas J; Swindles, Graeme T; Nasser, Nawaf A

2015-10-01

Organic rich sediments were obtained from seven core tops taken in Lake Quistococha, near the city of Iquitos in the Peruvian Amazon. Subsamples from 0 to 4cm depth in each core were analyzed under dissecting light microscopy to carry out the first investigation of Arcellinida (testate lobose amoebae) from a lacustrine environment in this ecologically important region. The fauna was characterized by a low diversity, low abundance community dominated by centropyxids. This fauna is similar to 'stressed' assemblages reported from temperate latitudes, except that test concentrations were two orders of magnitude lower than typical in temperate lakes. Principle arcellinidan stressors in Lake Quistococha likely include the low pH 4 conditions in the lake, and a general lack of suitable minerogenic material to construct tests in the organic rich lake substrate. The low pH conditions are the result of runoff and seepage of water high in dissolved organic carbon from the adjacent similarly low pH 4 terrestrial peatland. The dearth of minerogenic material is the result of the lake being isolated from riverine input for the past ∼2000 years, even during flooding events. Other limiting factors contributing to depressed arcellinidan populations may include nutrient supply, predation pressure, competition, and post-mortem taphonomic factors. Copyright © 2015 Elsevier GmbH. All rights reserved.

Molecular biomarkers for sources of organic matter in lacustrine sediments in a subtropical lake in China.

Science.gov (United States)

Wang, Yan-Hua; Yang, Hao; Chen, Xia; Zhang, Ji-Xiang; Ou, Jie; Xie, Biao; Huang, Chang-Chun

2013-05-01

N-alkanes distributions and stable isotopic compositions (δ(13)C and δ(15)N) in the lacustrine sediments of Shijiu lake were measured to assess whether biological source information was recorded in the molecular biomarker. Results showed regular unimodal n-alkanes distribution in range of C16-C33 with strong predominance of odd-numbered n-alkanes, maximizing at C29. The δ(15)N for SON were uniformly low, ranging from -6.7‰ to 3.8‰ and C/N ratios ranged from 6.6 to 10.0, suggesting that most of organic matter was influenced by terrestrial characteristics of the watershed. The δ(13)C for C27 to C31n-alkanes and for SOC varied from -32.9‰ to -26.6‰ and -23.4‰ to -21.6‰, respectively, falling within the range of corresponding n-alkanes in leaves mainly from C3 land plants. The values of C/N, CPI, OEP, ACL and C27/C31 exhibit similar temporal changes with the primary production, showing enhanced eutrophication resulted from increased anthropogenic activities in Shijiu lake from 1852 to 2010. Copyright © 2013 Elsevier Ltd. All rights reserved.

Some antarctic lacustrine sediments from northern Victoria Land investigation by Moessbauer spectroscopy, INNA and XRD

International Nuclear Information System (INIS)

Stievano, L.; Bertelle, M.; Leotta, G.; Calogero, S.; Constantinescu, S.; Oddone, M.

1999-01-01

Fifteen lacustrine sediments, sampled during the 1994-1995 Austral summer in Northern Victoria Land (Antarctica), were characterised by 57 Fe Moessbauer spectroscopy, instrumental neutron activation analysis and X-ray diffraction. These sediments are related to the intrusive rocks from Granite Harbour, to the metamorphic rocks of the Complex of Wilson Terrane and the volcanic rocks from Mc Murdo. The samples contain quartz, alkaline feldspars, plagioclases, amphiboles, biotite, chlorite and muscovite except for the sediments of volcanic origin that contain alkaline feldspars, plagioclases and pyroxenes. The paramagnetic components of the Moessbauer spectra were assigned mainly to the iron sides in biotites except for those displayed from the sediments of volcanic origin assigned mainly to pyroxenes. Moessbauer spectra at room temperature do not display magnetic ordering except for those of the sediments of volcanic origin containing bulk magnetite, hematite and goethite. Moessbauer spectra collected at the liquid helium temperature always exhibit magnetic ordering. This spectral difference has been attributed to the different dimensions of the iron oxide particles in the sediments. The scarce weathering involves a partial transformation of magnetite in hematite and goethite in the sediment of volcanic origin. In the remaining sediments a partial hydrolysis of biotite together with a partial oxidation of iron (II) retained in silicates is present. (authors)

Effect of mass variation on dynamics of tethered system in orbital maneuvering

Science.gov (United States)

Sun, Liang; Zhao, Guowei; Huang, Hai

2018-05-01

In orbital maneuvering, the mass variation due to fuel consumption has an obvious impact on the dynamics of tethered system, which cannot be neglected. The contributions of the work are mainly shown in two aspects: 1) the improvement of the model; 2) the analysis of dynamics characteristics. As the mass is variable, and the derivative of the mass is directly considered in the traditional Lagrange equation, the expression of generalized force is complicated. To solve this problem, the coagulated derivative is adopted in the paper; besides, the attitude dynamics equations derived in this paper take into account the effect of mass variation and the drift of orbital trajectory at the same time. The bifurcation phenomenon, the pendular motion angular frequency, and amplitudes of tether vibration revealed in this paper can provide a reference for the parameters and controller design in practical engineering. In the article, a dumbbell model is adopted to analyze the dynamics of tethered system, in which the mass variation of base satellite is fully considered. Considering the practical application, the case of orbital transfer under a transversal thrust is mainly studied. Besides, compared with the analytical solutions of librational angles, the effects of mass variation on stability and librational characteristic are studied. Finally, in order to make an analysis of the effect on vibrational characteristic, a lumped model is introduced, which reveals a strong coupling of librational and vibrational characteristics.

Stratigraphic architecture of a fluvial-lacustrine basin-fill succession at Desolation Canyon, Uinta Basin, Utah: Reference to Walthers’ Law and implications for the petroleum industry

Science.gov (United States)

Ford, Grace L.; David R. Pyles,; Dechesne, Marieke

2016-01-01

A continuous window into the fluvial-lacustrine basin-fill succession of the Uinta Basin is exposed along a 48-mile (77-kilometer) transect up the modern Green River from Three Fords to Sand Wash in Desolation Canyon, Utah. In ascending order the stratigraphic units are: 1) Flagstaff Limestone, 2) lower Wasatch member of the Wasatch Formation, 3) middle Wasatch member of the Wasatch Formation, 4) upper Wasatch member of the Wasatch Formation, 5) Uteland Butte member of the lower Green River Formation, 6) lower Green River Formation, 7) Renegade Tongue of the lower Green River Formation, 8) middle Green River Formation, and 9) the Mahogany oil shale zone marking the boundary between the middle and upper Green River Formations. This article uses regional field mapping, geologic maps, photographs, and descriptions of the stratigraphic unit including: 1) bounding surfaces, 2) key upward stratigraphic characteristics within the unit, and 3) longitudinal changes along the river transect. This information is used to create a north-south cross section through the basin-fill succession and a detailed geologic map of Desolation Canyon. The cross section documents stratigraphic relationships previously unreported and contrasts with earlier interpretations in two ways: 1) abrupt upward shifts in the stratigraphy documented herein, contrast with the gradual interfingering relationships proposed by Ryder et al., (1976) and Fouch et al., (1994), 2) we document fluvial deposits of the lower and middle Wasatch to be distinct and more widespread than previously recognized. In addition, we document that the Uteland Butte member of the lower Green River Formation was deposited in a lacustrine environment in Desolation Canyon.

Solar System Chaos and its climatic and biogeochemical consequences

Science.gov (United States)

Ikeda, M.; Tada, R.; Ozaki, K.; Olsen, P. E.

2017-12-01

Insolation changes caused by changes in Earth's orbital parameters are the main driver of climatic variations, whose pace has been used for astronomically-calibrated geologic time scales of high accuracy to understand Earth system dynamics. However, the astrophysical models beyond several tens of million years ago have large uncertainty due to chaotic behavior of the Solar System, and its impact on amplitude modulation of multi-Myr-scale orbital variations and consequent climate changes has become the subject of debate. Here we show the geologic constraints on the past chaotic behavior of orbital cycles from early Mesozoic monsoon-related records; the 30-Myr-long lake level records of the lacustrine sequence in Newark-Hartford basins (North America) and 70-Myr-long biogenic silica (BSi) burial flux record of pelagic deep-sea chert sequence in Inuyama area (Japan). BSi burial flux of chert could be considered as proportional to the dissolved Si (DSi) input from chemical weathering on timescales longer than the residence time of DSi ( 100 kyr), because chert could represent a major sink for oceanic dissolved silica (Ikeda et al., 2017).These geologic records show multi-Myr cycles with similar frequency modulations of eccentricity solution of astronomical model La2010d (Laskar et al., 2011) compared with other astronomical solutions, but not exactly same. Our geologic records provide convincing evidence for the past chaotic dynamical behaviour of the Solar System and new and challenging additional constraints for astrophysical models. In addition, we find that ˜10 Myr cycle detected in monsoon proxies and their amplitude modulation of ˜2 Myr cycle may be related to the amplitude modulation of ˜2 Myr eccentricity cycle through non-linear process(es) of Earth system dynamics, suggesting possible impact of the chaotic behavior of Solar planets on climate change. Further impact of multi-Myr orbital cycles on global biogeochemical cycles will be discussed.

Wind influence on the course of sedimentation processes of the laminated lacustrine sediments of Lake Czechowskie

Science.gov (United States)

Wiśniewska, Daria; Kramkowski, Mateusz; Tyszkowski, Sebastian

2016-04-01

The studies of the laminated lacustrine sediments play a very important role in the analysis of climate change. They provide valuable information related to the response of the ecosystem to changes in the environment. The condition for the development of the annual lamination is calm sedimentation, which can be compromised by the movement of water caused by waving. The depth to which this movement affects depends on the shape of the lake basin as well as the velocity and direction of the wind. During the study of sedimentary processes of laminated deposits in Lake Czechowskie (Tuchola Forest, North Poland, 53°52'N, 18°14' E, 108 m asl), the following question arose: How strong was the influence of the wind on the processes of lacustrine sedimentation? The key in getting the answers was the use of GIS techniques. Lake Czechowskie has an area of 76.6 hectares; it has two deeps separated by a threshold: a deeper one of 33 m (maximum depth of the basin) in the central-eastern part, and a shallower of 13 m in the western part. The speed of movement of water that is able to move sediment from the bottom of the lake, called the orbital wave velocity, is the basis for the designation of areas where re-suspension takes place. To calculate the wave parameters, the process of mixing, as well as the designation of re-suspension zones, the tool-script Wave Model (Rohweder et al. 2008) in the program ArsGIS 10.1 was used. The input data were wind direction and velocity from the meteorological station of Wirty about 15 km away, bathymetric data from acoustic profiling, and the Maximum Orbital Wave Velocity. The elements taken into account include maximum wind velocity of the multi-year 1996-2013, with particular emphasis on hurricanes Ksawery (December 2013) and Yoda (November 2011), during which wind velocity exceeded 120 km/h. In addition, maximum wind velocity ever recorded in the Polish Lowlands was considered. On the basis of the modelling, the authors delimited the areas

Variation in stable isotopes of freshwater mussel shells in a Kentucky river system

Science.gov (United States)

Erhardt, A. M.; Haag, W.; Price, S.; Weisrock, D.

2017-12-01

Isotopic signatures in freshwater mussel shells can reflect environmental differences among streams and human impacts on river systems. In the southeastern United States, mussels exhibit extraordinary biodiversity, serve an important role as filter feeders, and are sensitive to environmental change. Additionally, their long life-span (up to 50 years) and seasonal shell deposition can permit high-resolution environmental reconstructions. We examined variation in shell stable isotope values among mussel species and locations throughout the Licking River system in Kentucky. We sampled 8 species at 11 locations. These species represented a range of life-history traits, and locations were distributed among tributaries and the main stem of the Licking River. Samples of the outer organic periostracum layer were analysed for organic δ13C and δ15N, while organic δ15N and inorganic δ13C and δ18O were measured in the inner carbonate portion of the shell. At the same location, preliminary results show variations 2‰ in δ13C and 1‰ in δ15N between different species. We suspect these relationships are due to variations in diet and/or body size. Some, though not all, specimens show variation along the growth axis. For the same species at different locations, preliminary results showed a range of 4‰ in δ13C and 10‰ in δ15N values. Isotope ratios of specimens from the main stem were distinct from those of specimens from the river's largest tributary. Overall, δ13C shows distinct values for each tributary, while δ15N shows a general decline downstream. These variations are likely the result of environmental factors such as the degree of karstification and the ratio of forest to pasture within the catchment. We hope to use this study to identify if any isotopically distinct sources, such as fertilizers or animal manure, contribute to the high nutrient load in these systems. These results represent an exploratory effort to describe watershed-scale and mussel

Hybrid three-dimensional variation and particle filtering for nonlinear systems

International Nuclear Information System (INIS)

Leng Hong-Ze; Song Jun-Qiang

2013-01-01

This work addresses the problem of estimating the states of nonlinear dynamic systems with sparse observations. We present a hybrid three-dimensional variation (3DVar) and particle piltering (PF) method, which combines the advantages of 3DVar and particle-based filters. By minimizing the cost function, this approach will produce a better proposal distribution of the state. Afterwards the stochastic resampling step in standard PF can be avoided through a deterministic scheme. The simulation results show that the performance of the new method is superior to the traditional ensemble Kalman filtering (EnKF) and the standard PF, especially in highly nonlinear systems

1H NMR-based metabolic profiling reveals inherent biological variation in yeast and nematode model systems

International Nuclear Information System (INIS)

Szeto, Samuel S. W.; Reinke, Stacey N.; Lemire, Bernard D.

2011-01-01

The application of metabolomics to human and animal model systems is poised to provide great insight into our understanding of disease etiology and the metabolic changes that are associated with these conditions. However, metabolomic studies have also revealed that there is significant, inherent biological variation in human samples and even in samples from animal model systems where the animals are housed under carefully controlled conditions. This inherent biological variability is an important consideration for all metabolomics analyses. In this study, we examined the biological variation in 1 H NMR-based metabolic profiling of two model systems, the yeast Saccharomyces cerevisiae and the nematode Caenorhabditis elegans. Using relative standard deviations (RSD) as a measure of variability, our results reveal that both model systems have significant amounts of biological variation. The C. elegans metabolome possesses greater metabolic variance with average RSD values of 29 and 39%, depending on the food source that was used. The S. cerevisiae exometabolome RSD values ranged from 8% to 12% for the four strains examined. We also determined whether biological variation occurs between pairs of phenotypically identical yeast strains. Multivariate statistical analysis allowed us to discriminate between pair members based on their metabolic phenotypes. Our results highlight the variability of the metabolome that exists even for less complex model systems cultured under defined conditions. We also highlight the efficacy of metabolic profiling for defining these subtle metabolic alterations.

Repeatability of fractional flow reserve despite variations in systemic and coronary hemodynamics

NARCIS (Netherlands)

Johnson, N.P.; Johnson, D.T.; Kirkeeide, R.L.; Berry, C.; de Bruyne, B.; Fearon, W.F.; Oldroyd, K.G.; Pijls, N.H.J.; Gould, K. Lance

2015-01-01

Objectives This study classified and quantified the variation in fractional flow reserve (FFR) due to fluctuations in systemic and coronary hemodynamics during intravenous adenosine infusion. Background Although FFR has become a key invasive tool to guide treatment, questions remain regarding its

Quantum Variational Calculus

OpenAIRE

Malinowska , Agnieszka B.; Torres , Delfim

2014-01-01

International audience; Introduces readers to the treatment of the calculus of variations with q-differences and Hahn difference operators Provides the reader with the first extended treatment of quantum variational calculus Shows how the techniques described can be applied to economic models as well as other mathematical systems This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of it...

Variation tolerant SoC design

Science.gov (United States)

Kozhikkottu, Vivek J.

The scaling of integrated circuits into the nanometer regime has led to variations emerging as a primary concern for designers of integrated circuits. Variations are an inevitable consequence of the semiconductor manufacturing process, and also arise due to the side-effects of operation of integrated circuits (voltage, temperature, and aging). Conventional design approaches, which are based on design corners or worst-case scenarios, leave designers with an undesirable choice between the considerable overheads associated with over-design and significantly reduced manufacturing yield. Techniques for variation-tolerant design at the logic, circuit and layout levels of the design process have been developed and are in commercial use. However, with the incessant increase in variations due to technology scaling and design trends such as near-threshold computing, these techniques are no longer sufficient to contain the effects of variations, and there is a need to address variations at all stages of design. This thesis addresses the problem of variation-tolerant design at the earliest stages of the design process, where the system-level design decisions that are made can have a very significant impact. There are two key aspects to making system-level design variation-aware. First, analysis techniques must be developed to project the impact of variations on system-level metrics such as application performance and energy. Second, variation-tolerant design techniques need to be developed to absorb the residual impact of variations (that cannot be contained through lower-level techniques). In this thesis, we address both these facets by developing robust and scalable variation-aware analysis and variation mitigation techniques at the system level. The first contribution of this thesis is a variation-aware system-level performance analysis framework. We address the key challenge of translating the per-component clock frequency distributions into a system-level application

Diurnal variation in the performance of rapid response systems: the role of critical care services-a review article.

Science.gov (United States)

Sundararajan, Krishnaswamy; Flabouris, Arthas; Thompson, Campbell

2016-01-01

The type of medical review before an adverse event influences patient outcome. Delays in the up-transfer of patients requiring intensive care are associated with higher mortality rates. Timely detection and response to a deteriorating patient constitute an important function of the rapid response system (RRS). The activation of the RRS for at-risk patients constitutes the system's afferent limb. Afferent limb failure (ALF), an important performance measure of rapid response systems, constitutes a failure to activate a rapid response team (RRT) despite criteria for calling an RRT. There are diurnal variations in hospital staffing levels, the performance of rapid response systems and patient outcomes. Fewer ward-based nursing staff at night may contribute to ALF. The diurnal variability in RRS activity is greater in unmonitored units than it is in monitored units for events that should result in a call for an RRT. RRT events include a significant abnormality in either the pulse rate, blood pressure, conscious state or respiratory rate. There is also diurnal variation in RRT summoning rates, with most activations occurring during the day. The reasons for this variation are mostly speculative, but the failure of the afferent limb of RRT activation, particularly at night, may be a factor. The term "circadian variation/rhythm" applies to physiological variations over a 24-h cycle. In contrast, diurnal variation applies more accurately to extrinsic systems. Circadian rhythm has been demonstrated in a multitude of bodily functions and disease states. For example, there is an association between disrupted circadian rhythms and abnormal vital parameters such as anomalous blood pressure, irregular pulse rate, aberrant endothelial function, myocardial infarction, stroke, sleep-disordered breathing and its long-term consequences of hypertension, heart failure and cognitive impairment. Therefore, diurnal variation in patient outcomes may be extrinsic, and more easily modifiable

Forsmark site investigation. Investigation of marine and lacustrine sediment in lakes. Field data 2003

Energy Technology Data Exchange (ETDEWEB)

Hedenstroem, Anna [SGU, Uppsala (Sweden)

2003-04-01

The aim of this activity is to describe the aerial and stratigraphical distribution of marine and lacustrine sediment i.e. sediment overlaying the glacial till and/or bedrock surface, in lakes in the Forsmark area. The investigation is carried out within areas where mapping of unconsolidated Quaternary deposits is presently carried out. Since small and shallow lakes cover a large part of the region, this work will give important information on the distribution and stratigraphy of sedimentary deposits not included in the regular mapping of unconsolidated Quaternary deposits within the site investigation programme. Samples were also collected for laboratory analyses of grain size distribution, mineralogical composition as well as the total content of C, N and S and calcium carbonate. The analyses will be carried out on selected samples of representative sedimentary units in order to characterise the chemical and physical properties of the unconsolidated deposits. The analytical data will be useful for the hydrogeological modelling and for models of the Quaternary evolution of the area. The mineralogical analyses of clay may provide information on the origin of the clay particles. One stratigraphic sequence from Lake Eckarfjaerden will be stored for later analyses, e.g. pollen analysis. This report includes field data from spring 2003. Together, the field data and the forthcoming results from the laboratory analyses will form the basis for construction of stratigraphical profiles to be presented in a following report in the fall 2003.

Forsmark site investigation. Investigation of marine and lacustrine sediment in lakes. Field data 2003

International Nuclear Information System (INIS)

Hedenstroem, Anna

2003-04-01

The aim of this activity is to describe the aerial and stratigraphical distribution of marine and lacustrine sediment i.e. sediment overlaying the glacial till and/or bedrock surface, in lakes in the Forsmark area. The investigation is carried out within areas where mapping of unconsolidated Quaternary deposits is presently carried out. Since small and shallow lakes cover a large part of the region, this work will give important information on the distribution and stratigraphy of sedimentary deposits not included in the regular mapping of unconsolidated Quaternary deposits within the site investigation programme. Samples were also collected for laboratory analyses of grain size distribution, mineralogical composition as well as the total content of C, N and S and calcium carbonate. The analyses will be carried out on selected samples of representative sedimentary units in order to characterise the chemical and physical properties of the unconsolidated deposits. The analytical data will be useful for the hydrogeological modelling and for models of the Quaternary evolution of the area. The mineralogical analyses of clay may provide information on the origin of the clay particles. One stratigraphic sequence from Lake Eckarfjaerden will be stored for later analyses, e.g. pollen analysis. This report includes field data from spring 2003. Together, the field data and the forthcoming results from the laboratory analyses will form the basis for construction of stratigraphical profiles to be presented in a following report in the fall 2003

Spatio-temporal variation of fish taxonomic composition in a South-East Asian flood-pulse system.

Science.gov (United States)

Kong, Heng; Chevalier, Mathieu; Laffaille, Pascal; Lek, Sovan

2017-01-01

The Tonle Sap Lake (TSL) is a flood-pulse system. It is the largest natural lake in South-East Asia and constitutes one of the largest fisheries over the world, supporting the livelihood of million peoples. Nonetheless, the Mekong River Basin is changing rapidly due to accelerating water infrastructure development (hydropower, irrigation, flood control, and water supply) and climate change, bringing considerable modifications to the annual flood-pulse of the TSL. Such modifications are expected to have strong impacts on fish biodiversity and abundance. This paper aims to characterize the spatio-temporal variations of fish taxonomic composition and to highlights the underlying determinants of these variations. For this purpose, we used data collected from a community catch monitoring program conducted at six sites during 141 weeks, covering two full hydrological cycles. For each week, we estimated beta diversity as the total variance of the site-by-species community matrix and partitioned it into Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD). We then performed multiple linear regressions to determine whether species richness, species abundances and water level explained the temporal variation in the contribution of site and species to beta diversity. Our results indicate strong temporal variation of beta diversity due to differential contributions of sites and species to the spatial variation of fish taxonomic composition. We further found that the direction, the shape and the relative effect of species richness, abundances and water level on temporal variation in LCBD and SCBD values greatly varied among sites, thus suggesting spatial variation in the processes leading to temporal variation in community composition. Overall, our results suggest that fish taxonomic composition is not homogeneously distributed over space and time and is likely to be impacted in the future if the flood-pulse dynamic of the system is

Record of late Pleistocene glaciation and deglaciation in the southern Cascade Range. I. Petrological evidence from lacustrine sediment in Upper Klamath Lake, southern Oregon

Science.gov (United States)

Reynolds, R.L.; Rosenbaum, J.G.; Rapp, J.; Kerwin, M.W.; Bradbury, J.P.; Colman, S.; Adam, D.

2004-01-01

Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. High magnetization corresponds to relatively fine particle size and lower magnetization to coarser particle size. This relation is not found in the Buck Lake core in a nearby, unglaciated catchment. Angular silt-sized volcanic rock fragments containing unaltered magnetite dominate the magnetic fraction in the late Pleistocene sediments but are absent in younger, low magnetization sediments. The finer grained, highly magnetic sediments contain high proportions of planktic diatoms indicative of cold, oligotrophic limnic conditions. Sediment with lower magnetite content contains populations of diatoms indicative of warmer, eutrophic limnic conditions. During the latter part of oxygen isotope stage 3 (about 37-25 ka), the magnetic properties record millennial-scale variations in glacial-flour content. The input of glacial flour was uniformly high during the Last Glacial Maximum, between about 21 and 16 ka. At about 16 ka, magnetite input, both absolute and relative to hematite, decreased abruptly, reflecting a rapid decline in glacially derived detritus. The decrease in magnetite transport into the lake preceded declines in pollen from both grass and sagebrush. A more gradual decrease in heavy mineral content over this interval records sediment starvation with the growth of marshes at the margins

Systems of general nonlinear set-valued mixed variational inequalities problems in Hilbert spaces

Directory of Open Access Journals (Sweden)

Cho Yeol

2011-01-01

Full Text Available Abstract In this paper, the existing theorems and methods for finding solutions of systems of general nonlinear set-valued mixed variational inequalities problems in Hilbert spaces are studied. To overcome the difficulties, due to the presence of a proper convex lower semi-continuous function, φ and a mapping g, which appeared in the considered problem, we have used some applications of the resolvent operator technique. We would like to point out that although many authors have proved results for finding solutions of the systems of nonlinear set-valued (mixed variational inequalities problems, it is clear that it cannot be directly applied to the problems that we have considered in this paper because of φ and g. 2000 AMS Subject Classification: 47H05; 47H09; 47J25; 65J15.

Global biogeography of mating system variation in seed plants.

Science.gov (United States)

Moeller, David A; Briscoe Runquist, Ryan D; Moe, Annika M; Geber, Monica A; Goodwillie, Carol; Cheptou, Pierre-Olivier; Eckert, Christopher G; Elle, Elizabeth; Johnston, Mark O; Kalisz, Susan; Ree, Richard H; Sargent, Risa D; Vallejo-Marin, Mario; Winn, Alice A

2017-03-01

Latitudinal gradients in biotic interactions have been suggested as causes of global patterns of biodiversity and phenotypic variation. Plant biologists have long speculated that outcrossing mating systems are more common at low than high latitudes owing to a greater predictability of plant-pollinator interactions in the tropics; however, these ideas have not previously been tested. Here, we present the first global biogeographic analysis of plant mating systems based on 624 published studies from 492 taxa. We found a weak decline in outcrossing rate towards higher latitudes and among some biomes, but no biogeographic patterns in the frequency of self-incompatibility. Incorporating life history and growth form into biogeographic analyses reduced or eliminated the importance of latitude and biome in predicting outcrossing or self-incompatibility. Our results suggest that biogeographic patterns in mating system are more likely a reflection of the frequency of life forms across latitudes rather than the strength of plant-pollinator interactions. © 2017 John Wiley & Sons Ltd/CNRS.

Anatomic variations in vascular and collecting systems of kidneys from deceased donors.

Science.gov (United States)

Costa, H C; Moreira, R J; Fukunaga, P; Fernandes, R C; Boni, R C; Matos, A C

2011-01-01

Nephroureterectomy for transplantation has increased owing to the greater number of deceased donors. Anatomic variations may complicate the procedure or, if unrecognized, compromise the viability of kidneys for transplantation. We reviewed 254 surgical descriptions of nephroureterectomy specimens from January 2008 to December 2009. All organs collected according by standard techniques were evaluated for age, cause of death, renal function, frequency of injury during the procedure, as well as variations in the vascular and collecting systems. The mean donor age was 42 years (range, 2-74). The mean serum creatinine was 1.2 mg/dL (range, 1.0-7.0). The causes of death were cerebrovascular cause (stroke; n = 130), traumatic brain injury (n = 81) or other cause (n = 43). Among the anatomic variations: 8.6% (n = 22) were right arterial anatomical variations: 19 cases with 2 arteries and 3 cases with 3 arteries. In 25 cases (9.8%) the identified variation was the left artery: 2 arteries (n = 23), 3 arteries (n = 1) and 4 arteries (n = 1). We observed 9.8% on right side and 1.5% on left side venous anatomic variations, including 24 cases with 2 veins on the right side and 4 cases with 2 veins on the left side. Three cases of a retroaortic left renal vein and 1 case of a retro necklace vein (anterior and posterior to the aorta). Two cases of ureteral duplication were noted on the left and 1 on the right kidney. There were 3 horseshoe and 1 pelvic kidney. In 7.5% of cases, an injury to the graft included ureteral (n = 3), arterial (n = 10), or venous (n = 6). The most common anatomic variation was arterial (17.8%). Duplication of the renal vein was more frequent on the right. The high incidences of anatomic variations require more attention in the dissection of the renal hilum to avoid an injury that may compromise the graft. Copyright © 2011 Elsevier Inc. All rights reserved.

Application of the authigenic 10Be/9Be dating method to Late Miocene-Pliocene sequences in the northern Danube Basin (Pannonian Basin System): Confirmation of heterochronous evolution of sedimentary environments

Science.gov (United States)

Šujan, Michal; Braucher, Régis; Kováč, Michal; Bourlès, Didier L.; Rybár, Samuel; Guillou, Valéry; Hudáčková, Natália

2016-02-01

Authigenic 10Be/9Be dating method was applied to lacustrine, deltaic and alluvial sequences of the northern Danube Basin (Pannonian Basin System), to bridge the insufficiency of geochronological data for the Late Miocene to Pliocene period. The measurements of 51 samples (both lacustrine and floodplain), ranging from 11.6 to 0.95 Ma are consistent with the existing magnetostratigraphic and biostratigraphic data standing mainly on the evolution degree of endemic mollusk fauna, mammals and dinocysts. This agreement confirms our assumption that the incoming beryllium fluxes remained constant over the studied time period and thus that the two initial 10Be/9Be ratios determined in actual Holocene/Late Pleistocene sediments (lacustrine and floodplain) are valid for these environments. The obtained ages indicate gradual progradation of the deltaic depositional systems across the Danube Basin with a clear time-transgressional character, replacing basin floor and shelfal environments. Deltaic sedimentation occurred firstly in the north at foothills of the Western Carpathians from 11.0 Ma, and changed to the alluvial environment after 10.5 Ma. At the same time (~ 10.5 Ma), the paleo-Danube deltaic system draining the Eastern Alps entered the study area from the Vienna Basin situated on the West. Later, the deltaic systems were merged in the central part of the basin and reached its southeastern margin at ~ 9.4 Ma. Regression of the Lake Pannon from the southernmost part of the study area is evidenced after 8.7 Ma. Alluvial deposition of meandering rivers lasting until 6.0-5.0 Ma followed and was interrupted by the early Pliocene basin inversion. Sedimentation of braided streams took place during the late Pliocene and Pleistocene, reflecting uplift of mountains surrounding the basin margins. This study documents the powerful potential of the authigenic 10Be/9Be dating method and its reliability in a basin with complicated tectonic and sedimentary history. It demonstrates that

Example Solar Electric Propulsion System asteroid tours using variational calculus

Science.gov (United States)

Burrows, R. R.

1985-01-01

Exploration of the asteroid belt with a vehicle utilizing a Solar Electric Propulsion System has been proposed in past studies. Some of those studies illustrated multiple asteroid rendezvous with trajectories obtained using approximate methods. Most of the inadequacies of those approximations are overcome in this paper, which uses the calculus of variations to calculate the trajectories and associated payloads of four asteroid tours. The modeling, equations, and solution techniques are discussed, followed by a presentation of the results.

Geochemical control on the reduction of U(VI) to mononuclear U(IV) species in lacustrine sediments

Science.gov (United States)

Stetten, L.; Mangeret, A.; Brest, J.; Seder-Colomina, M.; Le Pape, P.; Ikogou, M.; Zeyen, N.; Thouvenot, A.; Julien, A.; Alcalde, G.; Reyss, J. L.; Bombled, B.; Rabouille, C.; Olivi, L.; Proux, O.; Cazala, C.; Morin, G.

2018-02-01

Contaminated systems in which uranium (U) concentrations slightly exceed the geochemical background are of particular interest to identify natural processes governing U trapping and accumulation in Earth's surface environments. For this purpose, we examined the role of early diagenesis on the evolution of U speciation and mobility in sediments from an artificial lake located downstream from a former mining site. Sediment and pore water chemistry together with U and Fe solid state speciation were analyzed in sediment cores sampled down to 50 cm depth at four locations in the lake. These organic-rich sediments (∼12% organic C) exhibited U concentrations in the 40-80 mg kg-1 range. The sediment columns were anoxic 2-3 mm below the sediment-water interface and pore waters pH was circumneutral. Pore water chemistry profiles showed that organic carbon mineralization was associated with Fe and Mn reduction and was correlated with a decrease in dissolved U concentration with depth. Immobilization of U in the sediment was correlated with the reduction of U(VI) to U(IV) at depth, as shown by U LIII-edge XANES spectroscopic analysis. XANES and EXAFS spectroscopy at the Fe K-edge showed the reduction of structural Fe(III) to Fe(II) in phyllosilicate minerals with depth, coincident with U(VI) to U(IV) reduction. Thermodynamic modeling suggests that Fe(II) could act as a major reducing agent for U(VI) during early diagenesis of these sediments, leading to complete U reduction below ∼30 cm depth. Shell-by-shell and Cauchy-Wavelet analysis of U LIII-EXAFS spectra indicates that U(VI) and U(IV) are mainly present as mononuclear species bound to C, P or Si ligands. Chemical extractions confirmed that ∼60-80% of U was present as non-crystalline species, which emphasizes that such species should be considered when evaluating the fate of U in lacustrine environments and the efficiency of sediment remediation strategies.

The influence of variation of deuterium's concentration on the immunity system

International Nuclear Information System (INIS)

Tamaian, Radu

2007-01-01

Hydrogen's substitution by deuterium represents an environmental alteration at which the organism (in vivo) and the cells (in vitro), respectively, if they can't accommodate will recede. In this way the variations of deuterium's isotopic abundance can be compared with the environmental factors of stress (variations of temperature, quantity of nourishment, radiations, etc). As different forms of existence of life are more or less sensitive at environment's factors variations, so they respond in different ways to concentration variations of deuterium from the living environment/organism. Consequently the mammals' immunity system (IS) presents different feed-backs. The main results are stressed as follows: - a. The use as alimentary adjuvant of deuterium depleted water (DDW) in prolonged periods (21 days) increased the capacity of unspecific immunity defense against the specific bacterial aggression, both in Gram-positive bacteria (Streptococcus pneumoniae558) and of Gram-negative (Klebsiella pneumoniae507); - b. The immunosuppression determined by cyclophosphamide-alquilant agent with medullary depletion of white series reduced the survival of inoculated animals, even in the conditions in which the animals have received dietary supplement with DDW; - c. The immunosuppression through medullary depletion due to irradiation reduced also the survival of inoculated animals, even in the conditions in which the animals have received dietary supplement with DDW. Those mentioned herein lead to the hypothesis that prolonged administration of DDW simulates the unspecific immunity defence, probably through the stimulation of the hematogenic marrow and of lymphopoietic and granulopoietic stem cells. (author)

Asymptotics of decreasing solutions of coupled p-Laplacian systems in the framework of regular variation

Czech Academy of Sciences Publication Activity Database

Řehák, Pavel; Matucci, S.

2014-01-01

Roč. 193, č. 3 (2014), s. 837-858 ISSN 0373-3114 Institutional support: RVO:67985840 Keywords : decreasing solution * quasilinear system * Emden-Fowler system * Lane-Emden system * regular variation Subject RIV: BA - General Mathematics Impact factor: 1.065, year: 2014 http://link.springer.com/article/10.1007%2Fs10231-012-0303-9

A miniature ultrasonic actuator-control system for plant stem diameter micro-variation measurements

Science.gov (United States)

Measurements of micro-variations in plant stem diameter are potentially useful to optimize irrigation decision support systems that are based on plant physiological responses. However, for this technology to be suitable for field applications, problems associated with stem softness and micro variati...

{sup 1}H NMR-based metabolic profiling reveals inherent biological variation in yeast and nematode model systems

Energy Technology Data Exchange (ETDEWEB)

Szeto, Samuel S. W.; Reinke, Stacey N.; Lemire, Bernard D., E-mail: bernard.lemire@ualberta.ca [University of Alberta, Department of Biochemistry, School of Molecular and Systems Medicine (Canada)

2011-04-15

The application of metabolomics to human and animal model systems is poised to provide great insight into our understanding of disease etiology and the metabolic changes that are associated with these conditions. However, metabolomic studies have also revealed that there is significant, inherent biological variation in human samples and even in samples from animal model systems where the animals are housed under carefully controlled conditions. This inherent biological variability is an important consideration for all metabolomics analyses. In this study, we examined the biological variation in {sup 1}H NMR-based metabolic profiling of two model systems, the yeast Saccharomyces cerevisiae and the nematode Caenorhabditis elegans. Using relative standard deviations (RSD) as a measure of variability, our results reveal that both model systems have significant amounts of biological variation. The C. elegans metabolome possesses greater metabolic variance with average RSD values of 29 and 39%, depending on the food source that was used. The S. cerevisiae exometabolome RSD values ranged from 8% to 12% for the four strains examined. We also determined whether biological variation occurs between pairs of phenotypically identical yeast strains. Multivariate statistical analysis allowed us to discriminate between pair members based on their metabolic phenotypes. Our results highlight the variability of the metabolome that exists even for less complex model systems cultured under defined conditions. We also highlight the efficacy of metabolic profiling for defining these subtle metabolic alterations.

Stability of fine-grained TT-OSL and post-IR IRSL signals from a c. 1 Ma sequence of aeolian and lacustrine deposits from the Nihewan Basin (northern China)

DEFF Research Database (Denmark)

Liu, Jinfeng; Murray, Andrew Sean; Buylaert, Jan-Pieter

2016-01-01

We tested the suitability of the fine-grained quartz (4–11 μm) Optical Stimulated Luminescence (OSL) and thermally-transferred OSL (TT-OSL), and the fine-grained polymineral (4–11 μm) post-infrared IRSL (post-IR IRSL or pIRIR) signals for dating samples from aeolian-lacustrine deposits from...... accurate ones; nevertheless, these ages provide the first long series absolute chronology for study of local palaeolithic and geomorphic evolution history aside from the  magnetostratigraphical results available before this research....

Sedimentology and paleoenvironments of the Las Chacritas carbonate paleolake, Cañadón Asfalto Formation (Jurassic), Patagonia, Argentina

Science.gov (United States)

Cabaleri, Nora G.; Benavente, Cecilia A.

2013-02-01

The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the Cañadón Asfalto Rift Basin (Chubut province, Patagonia, Argentina). A detailed sedimentological analysis was performed in the Fossati depocenter to determine the paleoenvironments that developed in the context of this rift. The Las Chacritas Member represents a carbonate paleolake system with ramp-shaped margins associated with wetlands that were eventually affected by subaerial exposure and pedogenesis. This process is represented by three main subenvironments: a) a lacustrine setting sensu stricto (lacustrine limestone facies association), represented by Mudstones/Wackestones containing porifera spicules (F1), Intraclastic packstones (F6) and Tabular stromatolites (F10) in which deposition and diagenesis were entirely subaqueous; b) a palustrine setting (palustrine limestone facies association) containing Microbial Mudstones (F2), Intraclastic sandy packstone with ostracode remains (F3), Oncolitic packstone (F5), Brecciated limestone (F7) and Nodular-Mottled limestone (F8) representing shallow marginal areas affected by groundwater fluctuations and minor subaerial exposure; and c) a pedogenic paleoenvironment (pedogenic limestone facies association) including Intraclastic limestone (F4) and Packstones containing Microcodium (F9) facies displaying the major features of subaerial exposure, pedogenic diagenesis and the development of paleosols. The fluvial-palustrine-lacustrine succession shows a general shallow upward trend in which contraction-expansion cycles are represented (delimited by exposure and surface erosion). The variations in the successive formations reflect the responses to fluctuations in a combination of two major controls, the tectonic and local climatic variables. The predominance of the palustrine facies associations was

The nonholonomic variational principle

Energy Technology Data Exchange (ETDEWEB)

Krupkova, Olga [Department of Algebra and Geometry, Faculty of Science, Palacky University, Tomkova 40, 779 00 Olomouc (Czech Republic); Department of Mathematics, La Trobe University, Bundoora, Victoria 3086 (Australia)], E-mail: krupkova@inf.upol.cz

2009-05-08

A variational principle for mechanical systems and fields subject to nonholonomic constraints is found, providing Chetaev-reduced equations as equations for extremals. Investigating nonholonomic variations of the Chetaev type and their properties, we develop foundations of the calculus of variations on constraint manifolds, modelled as fibred submanifolds in jet bundles. This setting is appropriate to study general first-order 'nonlinear nonitegrable constraints' that locally are given by a system of first-order ordinary or partial differential equations. We obtain an invariant constrained first variation formula and constrained Euler-Lagrange equations both in intrinsic and coordinate forms, and show that the equations are the same as Chetaev equations 'without Lagrange multipliers', introduced recently by other methods. We pay attention to two possible settings: first, when the constrained system arises from an unconstrained Lagrangian system defined in a neighbourhood of the constraint, and second, more generally, when an 'internal' constrained system on the constraint manifold is given. In the latter case a corresponding unconstrained system need not be a Lagrangian, nor even exist. We also study in detail an important particular case: nonholonomic constraints that can be alternatively modelled by means of (co)distributions in the total space of the fibred manifold; in nonholonomic mechanics this happens whenever constraints affine in velocities are considered. It becomes clear that (and why) if the distribution is completely integrable (= the constraints are semiholonomic), the principle of virtual displacements holds and can be used to obtain the constrained first variational formula by a more or less standard procedure, traditionally used when unconstrained or holonomic systems are concerned. If, however, the constraint is nonintegrable, no significant simplifications are available. Among others, some properties of nonholonomic

Vascular Variations Associated with Intracranial Aneurysms.

Science.gov (United States)

Orakdogen, Metin; Emon, Selin Tural; Somay, Hakan; Engin, Taner; Is, Merih; Hakan, Tayfun

2017-01-01

To investigate the vascular variations in patients with intracranial aneurysm in circle of Willis. We used the data on 128 consecutive intracranial aneurysm cases. Cerebral angiography images were analyzed retrospectively. Arteries were grouped as anterior cerebral arterial system (ACS), posterior cerebral arterial system (PCS) and middle cerebral arterial system (MCS) for grouping vascular variations. Lateralization, being single/multiple, gender; and also any connection with accompanying aneurysms" number, localization, dimension, whether bleeding/incidental aneurysm has been inspected. Variations were demonstrated in 57.8% of the cases. The most common variation was A1 variation (34.4%). The rate of variations was 36.7%, 24.2% and 10.2% respectively in ACS, PCS and MCS. MCS variations were significantly higher in males. Anterior communicating artery (ACoA) aneurysm observance rates were significantly higher and posterior communicating artery (PCoA) aneurysm and middle cerebral artery (MCA) aneurysm observance rates were significantly lower when compared to "no ACS variation detected" cases. In "PCS variation detected" cases, PCoA aneurysm observance rates and coexistence of multiple variations were significantly higher. The rate of vascular variations in patients with aneurysms was 57.8%. Arterial hypoplasia and aplasia were the most common variations. ACS was the most common region that variations were located in; they were mostly detected on the right side. Coexistence of ACoA aneurysm was higher than PCoA and MCA aneurysms. In the PCS variations group, PCoA aneurysms were the most common aneurysms that accompanying the variation and multiple variations were more common than in the other two groups. The variations in MCS were most common in males.

A Variational Approach to the Modeling of MIMO Systems

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Jraifi A

2007-01-01

Full Text Available Motivated by the study of the optimization of the quality of service for multiple input multiple output (MIMO systems in 3G (third generation, we develop a method for modeling MIMO channel . This method, which uses a statistical approach, is based on a variational form of the usual channel equation. The proposed equation is given by with scalar variable . Minimum distance of received vectors is used as the random variable to model MIMO channel. This variable is of crucial importance for the performance of the transmission system as it captures the degree of interference between neighbors vectors. Then, we use this approach to compute numerically the total probability of errors with respect to signal-to-noise ratio (SNR and then predict the numbers of antennas. By fixing SNR variable to a specific value, we extract informations on the optimal numbers of MIMO antennas.

Solving Ratio-Dependent Predatorprey System with Constant Effort Harvesting Using Variational Iteration Method

DEFF Research Database (Denmark)

Ghotbi, Abdoul R; Barari, Amin

2009-01-01

Due to wide range of interest in use of bio-economic models to gain insight in to the scientific management of renewable resources like fisheries and forestry, variational iteration method (VIM) is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort...

``Use of perturbative methods to break down the variation of reactivity between two systems``; ``Decomposition par methodes perturbatives de la variation de reactivite de deux systemes``

Energy Technology Data Exchange (ETDEWEB)

Perruchot-Triboulet, S.; Sanchez, R.

1997-12-01

The modification of the isotopic composition, the temperature or even accounting for across section uncertainties in one part of a nuclear reactor core, affects the value of the effective multiplication factor. A new tool allows the analysis of the reactivity effect generated by the modification of the system. With the help of the direct and adjoint fluxes, a detailed balance of reactivity, between the compared systems, is done for each isotopic cross section. After the presentation of the direct and adjoint transport equations in the context of the multigroup code transport APOLLO2, this note describes the method, based on perturbation theory, for the analysis of the reactivity variation. An example application is also given. (author).

Ionic interactions in biological and physical systems: a variational treatment.

Science.gov (United States)

Eisenberg, Bob

2013-01-01

Chemistry is about chemical reactions. Chemistry is about electrons changing their configurations as atoms and molecules react. Chemistry has for more than a century studied reactions as if they occurred in ideal conditions of infinitely dilute solutions. But most reactions occur in salt solutions that are not ideal. In those solutions everything (charged) interacts with everything else (charged) through the electric field, which is short and long range extending to the boundaries of the system. Mathematics has recently been developed to deal with interacting systems of this sort. The variational theory of complex fluids has spawned the theory of liquid crystals (or vice versa). In my view, ionic solutions should be viewed as complex fluids, particularly in the biological and engineering context. In both biology and electrochemistry ionic solutions are mixtures highly concentrated (to approximately 10 M) where they are most important, near electrodes, nucleic ids, proteins, active sites of enzymes, and ionic channels. Ca2+ is always involved in biological solutions because the concentration (really free energy per mole) of Ca2+ in a particular location is the signal that controls many biological functions. Such interacting systems are not simple fluids, and it is no wonder that analysis of interactions, such as the Hofmeister series, rooted in that tradition has not succeeded as one would hope. Here, we present a variational treatment of ard spheres in a frictional dielectric with the hope that such a treatment of an lectrolyte as a complex fluid will be productive. The theory automatically extends to spatially nonuniform boundary conditions and the nonequilibrium systems and flows they produce. The theory is unavoidably self-consistent since differential equations are derived (not assumed) from models of (Helmholtz free) nergy and dissipation of the electrolyte. The origin of the Hofmeister series is (in my view) an inverse problem that becomes well posed when

Variational integrators for electric circuits

International Nuclear Information System (INIS)

Ober-Blöbaum, Sina; Tao, Molei; Cheng, Mulin; Owhadi, Houman; Marsden, Jerrold E.

2013-01-01

In this contribution, we develop a variational integrator for the simulation of (stochastic and multiscale) electric circuits. When considering the dynamics of an electric circuit, one is faced with three special situations: 1. The system involves external (control) forcing through external (controlled) voltage sources and resistors. 2. The system is constrained via the Kirchhoff current (KCL) and voltage laws (KVL). 3. The Lagrangian is degenerate. Based on a geometric setting, an appropriate variational formulation is presented to model the circuit from which the equations of motion are derived. A time-discrete variational formulation provides an iteration scheme for the simulation of the electric circuit. Dependent on the discretization, the intrinsic degeneracy of the system can be canceled for the discrete variational scheme. In this way, a variational integrator is constructed that gains several advantages compared to standard integration tools for circuits; in particular, a comparison to BDF methods (which are usually the method of choice for the simulation of electric circuits) shows that even for simple LCR circuits, a better energy behavior and frequency spectrum preservation can be observed using the developed variational integrator

Lithostratigraphy and physical properties of lacustrine sediments of the last ca. 150 kyr from Chalco basin, central México

Science.gov (United States)

Ortega-Guerrero, Beatriz; Lozano-García, Socorro; Herrera-Hernández, Dimitris; Caballero, Margarita; Beramendi-Orosco, Laura; Bernal, Juan Pablo; Torres-Rodríguez, Esperanza; Avendaño-Villeda, Diana

2017-11-01

The recognition of past climatic fluctuations in sedimentary sequences in central Mexico is relevant for understanding the forcing mechanisms and responses of climatic system in the northern American tropic. Moreover, in this active volcanic setting the sedimentary record preserves the history of past volcanic activity. Climatic and environmental variability has been documented for the last tenths of thousands of years from the upper lacustrine sediments in Chalco basin. A series of cores drilled down to 122 m depth in this basin offer a long, continuous and high resolution record of past climatic changes of the last ca. 150 kyr in this region. Here we present the detailed lithostratigraphy and some physical properties (magnetic susceptibility and density) of the master sequence. Sedimentary components and their abundance were identified and quantified in smear slides and direct core observations. Age model is based on 13 14C and one 230Th/U dates. Based on their facies association seven lithostratigraphic units were defined, which reflect the main stages of lake Chalco evolution. These phases closely match the marine isotopic stages. The data reveal that at the end of MIS6 Chalco was a relatively deep and stratified freshwater lake. During MIS5 the depositional environment fluctuated between low lake stands to marshy and marginal playa settings with sporadic flooding events, and severe arid periods resulted in aerial exposure of lake sediments. Low lake stands persisted during MIS4 and MIS3, with minor fluctuations towards slightly deeper phases. The Last Glacial Maximum (LGM) and the deglacial period (21-13 kyr) are characterized by intense volcanism. The early and mid-Holocene high calcareous content and alkaline-subsaline lake suggest dry conditions. The fluctuations of lake levels inferred provide the basis for future paleoclimatic works.

Holocene paleoclimatic variation in the Schirmacher Oasis, East Antarctica: A mineral magnetic approach

Science.gov (United States)

Phartiyal, Binita

2014-12-01

An analysis of remanent magnetism and radiocarbon ages in the dry lacustrine/sediment fills of the Schirmacher Oasis (SO) in East Antarctica was conducted to reconstruct past climatic condition. The statistically run mineral magnetic data on paleontological statistics software package (multivariate cluster analysis) placed on accelerator mass spectrometer radiocarbon chronology of the three sediment sections, trace 6 phases of climatic fluctuation between 13 and 3 ka, (Phases 1, 3 and 5 represent cold periods while Phases 2, 4, and 6 represent warm periods). One short warm period (Phase 2, ca. 12.5 ka) occurred in the late Pleistocene, and two marked warm periods (Phase 4, 11-8.7 ka; Phase 6, 4.4-3 ka) occurred in the Holocene. High magnetic susceptibility (χ), saturation isothermal remanent magnetism (SIRM), and soft isothermal remanent magnetism (soft IRM) values correspond to colder periods and low values reflect comparatively warmer lacustrine phases. Holocene Optima (Phase 4) and Mid Holocene Hypsithermal (Phase 6) are distinguished by decreased values of concentrations dependent parameters. Remanence is preserved in the low-coercive minerals. Heavy metals in the sediments include, Fe, Rb, Zn, Mo, Co, Pb, Mn, Cu, and As in order of decreasing abundance.

A survey of variational principles

International Nuclear Information System (INIS)

Lewins, J.D.

1993-01-01

In this article survey of variational principles has been given. Variational principles play a significant role in mathematical theory with emphasis on the physical aspects. There are two principals used i.e. to represent the equation of the system in a succinct way and to enable a particular computation in the system to be carried out with greater accuracy. The survey of variational principles has ranged widely from its starting point in the Lagrange multiplier to optimisation principles. In an age of digital computation, these classic methods can be adapted to improve such calculations. We emphasize particularly the advantage of basic finite element methods on variational principles. (A.B.)

Structure analyses of swollen rubber-carbon black systems by contrast variation SANS

International Nuclear Information System (INIS)

Takenaka, Mikihito; Nishitsuji, Shotaro; Fujii, Sumiaki; Amino, Naoya; Ishikawa, Yasuhiro; Yamaguchi, Daisuke; Koizumi, Satoshi

2010-01-01

The polymer layers adsorbed on carbon black (CB) aggregates in rubber/CB systems have been investigated with contrast variation small-angle neutron scattering (SANS) method. Specimens were swollen by toluene/deuterated toluene solvents having various scattering length densities and their scattering intensities were measured with SANS. The contrast variation SANS for the specimens yielded partial scattering functions: the scattering function for polymer-polymer correlation S pp (q), the scattering function for CB- CB correlation S cc (q), and the scattering function for polymer- CB correlation S pc (q). The analyses of the partial scattering functions explored the existence of dense polymer layers around CB aggregates. Several characteristic parameters are estimated from the analyses, such as the size of aggregates, the thickness of layers, and the volume fractions of polymer of layers and matrix. (author)

Multi-Decadal to Millennial Scale Holocene Hydrologic Variation in the Southern Hemisphere Tropics of South America

Science.gov (United States)

Ekdahl, E. J.; Fritz, S. C.; Baker, P. A.; Burns, S. J.; Coley, K.; Rigsby, C. A.

2005-12-01

Numerous sites in the Northern Hemisphere show multi-decadal to millennial scale climate variation during the Holocene, many of which have been correlated with changes in atmospheric radiocarbon production or with changes in North Atlantic oceanic circulation. The manifestation of such climate variability in the hydrology of the Southern Hemisphere tropics of South America is unclear, because of the limited number of records at suitably high resolution. In the Lake Titicaca drainage basin of Bolivia and Peru, high-resolution lacustrine records reveal the overall pattern of Holocene lake-level change, the influence of precessional forcing of the South American Summer Monsoon, and the effects of high-frequency climate variability in records of lake productivity and lake ecology. Precessional forcing of regional precipitation is evident in the Lake Titicaca basin as a massive (ca. 85 m) mid-Holocene decline in lake level beginning about 7800 cal yr BP and a subsequent rise in lake level after 4000 cal yr BP. Here we show that multi-decadal to millennial-scale climate variability, superimposed upon the envelope of change at orbital time scales, is similar in timing and pattern to the ice-rafted debris record of Holocene Bond events in the North Atlantic. A high-resolution carbon isotopic record from Lake Titicaca that spans the entire Holocene suggests that cold intervals of Holocene Bond events are periods of increased precipitation, thus indicating an anti-phasing of precipitation variation on the Altiplano relative to the Northern Hemisphere tropics. A similar pattern of variation is also evident in high-resolution (2-30 yr spacing) diatom and geochemical records that span the last 7000 yr from two smaller lakes, Lagos Umayo and Lagunillas, in the Lake Titicaca drainage basin.

Genetic Variation in the Dopamine System Influences Intervention Outcome in Children with Cerebral Palsy

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Rochellys Diaz Heijtz

2018-02-01

Interpretation: Naturally occurring genetic variation in the dopamine system can influence treatment outcomes in children with cerebral palsy. A polygenic dopamine score might be valid for treatment outcome prediction and for designing individually tailored interventions for children with cerebral palsy.

Consideration of the accuracy by variation of respiration in real-time position management respiratory gating system

International Nuclear Information System (INIS)

Na, Jun Young; Kang, Tae Young; Beak, Geum Mun; Kwon, Gyeong Tae

2013-01-01

Respiratory Gated Radiation Therapy (RGRT) has been carried out using RPM (Real-time Position Management) Respiratory Gating System (version 1.7.5, varian, USA) in Asan Medical Center. This study was to analyze and evaluate the accuracy of Respiratory Gated Radiation Therapy (RGRT) according to variation of respiration. Making variation of respiration using Motion Phantom:QUASAR Programmable Respiratory Motion Phantom (Moudus Medical Device Inc. CANADA) able to adjust respiration pattern randomly was varying period, amplitude and baseline by analyze 50 patient's respiration of lung and liver cancer. One of the variations of respiration is baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. The other variation of respiration is baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm. Experiments were performed in the same way that is used RPM Respiratory Gating System (phase gating, usually 30-70% gating) in Asan Medical Center. It was all exposed radiation under one of the conditions of baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. Under the other condition of baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm equally radiation was exposed. The variations of baseline shifts didn't accurately reflect on phase gating in RPM Respiratory Gating System. This inexactitude makes serious uncertainty in Respiratory Gated Radiation Therapy. So, Must be stabilized breathing of patient before conducting Respiratory Gated Radiation Therapy. also must be monitored breathing of patient in the middle of treatment. If you observe considerable changes of breathing when conducting Respiratory Gated Radiation Therapy. Stopping treatment immediately and then must be need to recheck treatment site using fluoroscopy. If patient's respiration rechecked using fluoroscopy restabilize, it is possible to restart Respiratory Gated Radiation Therapy

A neural network method for solving a system of linear variational inequalities

International Nuclear Information System (INIS)

Lan Hengyou; Cui Yishun

2009-01-01

In this paper, we transmute the solution for a new system of linear variational inequalities to an equilibrium point of neural networks, and by using analytic technique, some sufficient conditions are presented. Further, the estimation of the exponential convergence rates of the neural networks is investigated. The new and useful results obtained in this paper generalize and improve the corresponding results of recent works.

Vibration control of an MR vehicle suspension system considering both hysteretic behavior and parameter variation

International Nuclear Information System (INIS)

Choi, Seung-Bok; Seong, Min-Sang; Ha, Sung-Hoon

2009-01-01

This paper presents vibration control responses of a controllable magnetorheological (MR) suspension system considering the two most important characteristics of the system; the field-dependent hysteretic behavior of the MR damper and the parameter variation of the suspension. In order to achieve this goal, a cylindrical MR damper which is applicable to a middle-sized passenger car is designed and manufactured. After verifying the damping force controllability, the field-dependent hysteretic behavior of the MR damper is identified using the Preisach hysteresis model. The full-vehicle suspension model is then derived by considering vertical, pitch and roll motions. An H ∞ controller is designed by treating the sprung mass of the vehicle as a parameter variation and integrating it with the hysteretic compensator which produces additional control input. In order to demonstrate the effectiveness and robustness of the proposed control system, the hardware-in-the-loop simulation (HILS) methodology is adopted by integrating the suspension model with the proposed MR damper. Vibration control responses of the vehicle suspension system such as vertical acceleration are evaluated under both bump and random road conditions

A Simply Constrained Optimization Reformulation of KKT Systems Arising from Variational Inequalities

International Nuclear Information System (INIS)

Facchinei, F.; Fischer, A.; Kanzow, C.; Peng, J.-M.

1999-01-01

The Karush-Kuhn-Tucker (KKT) conditions can be regarded as optimality conditions for both variational inequalities and constrained optimization problems. In order to overcome some drawbacks of recently proposed reformulations of KKT systems, we propose casting KKT systems as a minimization problem with nonnegativity constraints on some of the variables. We prove that, under fairly mild assumptions, every stationary point of this constrained minimization problem is a solution of the KKT conditions. Based on this reformulation, a new algorithm for the solution of the KKT conditions is suggested and shown to have some strong global and local convergence properties

General variational many-body theory with complete self-consistency for trapped bosonic systems

International Nuclear Information System (INIS)

Streltsov, Alexej I.; Alon, Ofir E.; Cederbaum, Lorenz S.

2006-01-01

In this work we develop a complete variational many-body theory for a system of N trapped bosons interacting via a general two-body potential. The many-body solution of this system is expanded over orthogonal many-body basis functions (configurations). In this theory both the many-body basis functions and the respective expansion coefficients are treated as variational parameters. The optimal variational parameters are obtained self-consistently by solving a coupled system of noneigenvalue--generally integro-differential--equations to get the one-particle functions and by diagonalizing the secular matrix problem to find the expansion coefficients. We call this theory multiconfigurational Hartree theory for bosons or MCHB(M), where M specifies explicitly the number of one-particle functions used to construct the configurations. General rules for evaluating the matrix elements of one- and two-particle operators are derived and applied to construct the secular Hamiltonian matrix. We discuss properties of the derived equations. We show that in the limiting cases of one configuration the theory boils down to the well-known Gross-Pitaevskii and the recently developed multi-orbital mean fields. The invariance of the complete solution with respect to unitary transformations of the one-particle functions is utilized to find the solution with the minimal number of contributing configurations. In the second part of our work we implement and apply the developed theory. It is demonstrated that for any practical computation where the configurational space is restricted, the description of trapped bosonic systems strongly depends on the choice of the many-body basis set used, i.e., self-consistency is of great relevance. As illustrative examples we consider bosonic systems trapped in one- and two-dimensional symmetric and asymmetric double well potentials. We demonstrate that self-consistency has great impact on the predicted physical properties of the ground and excited states

Resonant activation in 2D and 3D systems driven by multi-variate Lévy noise

International Nuclear Information System (INIS)

Szczepaniec, Krzysztof; Dybiec, Bartłomiej

2014-01-01

Resonant activation is one of the classical effects demonstrating the constructive role of noise. In resonant activation, the cooperative action of a barrier modulation process and noise lead to the optimal escape kinetics as measured by the mean first passage time. Resonant activation has been observed in versatile systems for various types of barrier modulation process and noise type. Here, we show that resonant activation is also observed in 2D and 3D systems driven by bi-variate and tri-variate α-stable noise. The strength of resonant activation is sensitive to the exact value of the noise parameters. In particular, the decrease in the stability index α results in the disappearance of the resonant activation. (paper)

Genetic variations in the serotoninergic system contribute to body-mass index in Chinese adolescents.

Directory of Open Access Journals (Sweden)

Chunhui Chen

Full Text Available OBJECTIVE: Obesity has become a worldwide health problem in the past decades. Human and animal studies have implicated serotonin in appetite regulation, and behavior genetic studies have shown that body mass index (BMI has a strong genetic component. However, the roles of genes related to the serotoninergic (5-hydroxytryptamine,5-HT system in obesity/BMI are not well understood, especially in Chinese subjects. SUBJECTS AND DESIGN: With a sample of 478 healthy Chinese volunteers, this study investigated the relation between BMI and genetic variations of the serotoninergic system as characterized by 136 representative polymorphisms. We used a system-level approach to identify SNPs associated with BMI, then estimated their overall contribution to BMI by multiple regression and verified it by permutation. RESULTS: We identified 12 SNPs that made statistically significant contributions to BMI. After controlling for gender and age, four of these SNPs accounted for 7.7% additional variance of BMI. Permutation analysis showed that the probability of obtaining these findings by chance was low (p = 0.015, permuted for 1000 times. CONCLUSION: These results showed that genetic variations in the serotoninergic system made a moderate contribution to individual differences in BMI among a healthy Chinese sample, suggesting that a similar approach can be used to study obesity.

Variational data assimilation system "INM RAS - Black Sea"

Science.gov (United States)

Parmuzin, Eugene; Agoshkov, Valery; Assovskiy, Maksim; Giniatulin, Sergey; Zakharova, Natalia; Kuimov, Grigory; Fomin, Vladimir

2013-04-01

Development of Informational-Computational Systems (ICS) for Data Assimilation Procedures is one of multidisciplinary problems. To study and solve these problems one needs to apply modern results from different disciplines and recent developments in: mathematical modeling; theory of adjoint equations and optimal control; inverse problems; numerical methods theory; numerical algebra and scientific computing. The problems discussed above are studied in the Institute of Numerical Mathematics of the Russian Academy of Science (INM RAS) in ICS for Personal Computers (PC). Special problems and questions arise while effective ICS versions for PC are being developed. These problems and questions can be solved with applying modern methods of numerical mathematics and by solving "parallelism problem" using OpenMP technology and special linear algebra packages. In this work the results on the ICS development for PC-ICS "INM RAS - Black Sea" are presented. In the work the following problems and questions are discussed: practical problems that can be studied by ICS; parallelism problems and their solutions with applying of OpenMP technology and the linear algebra packages used in ICS "INM - Black Sea"; Interface of ICS. The results of ICS "INM RAS - Black Sea" testing are presented. Efficiency of technologies and methods applied are discussed. The work was supported by RFBR, grants No. 13-01-00753, 13-05-00715 and by The Ministry of education and science of Russian Federation, project 8291, project 11.519.11.1005 References: [1] V.I. Agoshkov, M.V. Assovskii, S.A. Lebedev, Numerical simulation of Black Sea hydrothermodynamics taking into account tide-forming forces. Russ. J. Numer. Anal. Math. Modelling (2012) 27, No.1, 5-31 [2] E.I. Parmuzin, V.I. Agoshkov, Numerical solution of the variational assimilation problem for sea surface temperature in the model of the Black Sea dynamics. Russ. J. Numer. Anal. Math. Modelling (2012) 27, No.1, 69-94 [3] V.B. Zalesny, N.A. Diansky, V

Stability region for a prompt power variation of a coupled-core system with positive prompt feedback

International Nuclear Information System (INIS)

Watanabe, S.; Nishina, K.

1984-01-01

A stability analysis using a one-group model is presented for a coupled-core system. Positive prompt feedback of a γp /SUB j/ form is assumed, where p /SUB j/ is the fractional power variation of core j. Prompt power variations over a range of a few milliseconds after a disturbance are analyzed. The analysis combines Lapunov's method, prompt jump approximation, and the eigenfunction expansion of coupling region response flux. The last is treated as a pseudo-delayed neutron precursor. An asymptotic stability region is found for p /SUB j/. For an asymmetric flux variation over a system of two coupled cores, either p /SUB I/ or p /SUB II/ can slightly exceed, by virtue of the coupling effect, the critical value (β/γ-1) of a single-core case. Such a stability region is increased by additional inclusion of the coupling region fundamental mode in the treatment. The coupling region contributes to stability through its delayed response and coupling. An optimum core separation distance for stability is found

Structure analyses of swollen rubber-filler systems by using contrast variation Small angle neutron scattering (SANS)

International Nuclear Information System (INIS)

Takenaka, Mikihito; Nishitsuji, Shotaro; Yamaguchi, Daisuke; Koizumi, Satoshi

2009-01-01

Full text: The polymer layers absorbed on silica particles in rubber-silica systems have investigated with contrast variation small-angle neutron scattering (SANS) method. The scattering intensities of specimens swollen by the solvents having various scattering length densities were measured. The contrast variation SANS for the specimens yielded partial scattering functions: the scattering function for polymer-polymer correlation SPP(q), the scattering function for silica- silica correlation SSS(q), and the scattering function for polymer- silica correlation SPS(q). The analyses of SSS(q) explored the hierarchical structures formed by silica particles. The analyses of SPS(q) and SSS(q) clarified the existence of dense polymer layers around silica aggregates. Several characteristic parameters are estimated from the analyses, such as the size of aggregates, the thickness of layers, the volume fractions of polymer of layers and matrix, and the correlation length of the matrix network. The contrast variation SANS is found to be a powerful tool of the analyses of the structures of the rubber-filler systems. (author)

Finite-Temperature Variational Monte Carlo Method for Strongly Correlated Electron Systems

Science.gov (United States)

Takai, Kensaku; Ido, Kota; Misawa, Takahiro; Yamaji, Youhei; Imada, Masatoshi

2016-03-01

A new computational method for finite-temperature properties of strongly correlated electrons is proposed by extending the variational Monte Carlo method originally developed for the ground state. The method is based on the path integral in the imaginary-time formulation, starting from the infinite-temperature state that is well approximated by a small number of certain random initial states. Lower temperatures are progressively reached by the imaginary-time evolution. The algorithm follows the framework of the quantum transfer matrix and finite-temperature Lanczos methods, but we extend them to treat much larger system sizes without the negative sign problem by optimizing the truncated Hilbert space on the basis of the time-dependent variational principle (TDVP). This optimization algorithm is equivalent to the stochastic reconfiguration (SR) method that has been frequently used for the ground state to optimally truncate the Hilbert space. The obtained finite-temperature states allow an interpretation based on the thermal pure quantum (TPQ) state instead of the conventional canonical-ensemble average. Our method is tested for the one- and two-dimensional Hubbard models and its accuracy and efficiency are demonstrated.

Variational integrators in plasma physics

International Nuclear Information System (INIS)

Kraus, Michael

2013-01-01

To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

Techniques to assess biological variation in destructive data

NARCIS (Netherlands)

Tijskens, L.M.M.; Schouten, R.E.; Jongbloed, G.; Konopacki, P.J.

2018-01-01

Variation is present in all measured data, due to variation between individuals (biological variation) and variation induced by the measuring system (technical variation). Biological variation present in experimental data is not the result of a random process but strictly subject to deterministic

TRANSIT TIMING VARIATIONS FOR INCLINED AND RETROGRADE EXOPLANETARY SYSTEMS

International Nuclear Information System (INIS)

Payne, Matthew J.; Ford, Eric B.; Veras, Dimitri

2010-01-01

We perform numerical calculations of the expected transit timing variations (TTVs) induced on a hot-Jupiter by an Earth-mass perturber. Motivated by the recent discoveries of retrograde transiting planets, we concentrate on an investigation of the effect of varying relative planetary inclinations, up to and including completely retrograde systems. We find that planets in low-order (e.g., 2:1) mean-motion resonances (MMRs) retain approximately constant TTV amplitudes for 0 deg. 170 deg. Systems in higher order MMRs (e.g., 5:1) increase in TTV amplitude as inclinations increase toward 45 deg., becoming approximately constant for 45 deg. 135 deg. Planets away from resonance slowly decrease in TTV amplitude as inclinations increase from 0 deg. to 180 deg., whereas planets adjacent to resonances can exhibit a huge range of variability in TTV amplitude as a function of both eccentricity and inclination. For highly retrograde systems (135 deg. < i ≤ 180 deg.), TTV signals will be undetectable across almost the entirety of parameter space, with the exceptions occurring when the perturber has high eccentricity or is very close to an MMR. This high inclination decrease in TTV amplitude (on and away from resonance) is important for the analysis of the known retrograde and multi-planet transiting systems, as inclination effects need to be considered if TTVs are to be used to exclude the presence of any putative planetary companions: absence of evidence is not evidence of absence.

Boundary Equations and Regularity Theory for Geometric Variational Systems with Neumann Data

Science.gov (United States)

Schikorra, Armin

2018-02-01

We study boundary regularity of maps from two-dimensional domains into manifolds which are critical with respect to a generic conformally invariant variational functional and which, at the boundary, intersect perpendicularly with a support manifold. For example, harmonic maps, or H-surfaces, with a partially free boundary condition. In the interior it is known, by the celebrated work of Rivière, that these maps satisfy a system with an antisymmetric potential, from which one can derive the interior regularity of the solution. Avoiding a reflection argument, we show that these maps satisfy along the boundary a system of equations which also exhibits a (nonlocal) antisymmetric potential that combines information from the interior potential and the geometric Neumann boundary condition. We then proceed to show boundary regularity for solutions to such systems.

Sedimentary cyclicity in early Pleistocene, evaporitic, playa-lake lacustrine deposits in the Guadix-Baza basin (Betic Cordillera, Spain); Ciclicidad sedimentaria en depositos lacustres evaporiticos tipo playa-lake del Pleistoceno inferior en la cuenca de Guadix-Baza (Cordillera Betica, Espana)

Energy Technology Data Exchange (ETDEWEB)

Garcia Aguilar, J. M.; Guera-Menchan, A.; Serrano, F.; Palmqvist, P.

2013-06-01

The Guadix-Baza basin (Betic Cordillera, southern Spain) contains in its eastern sector an early Pleistocene (Gelasian and lowermost Calabrian) sedimentary unit that was deposited in a shallow lacustrine environment. Given that the chronological limits of this unit lie between 2.5 and 1.6 Ma BP, the thickness of its preserved sediments (400 m) and high sedimentation rate (44.4 cm/ka) are remarkable. Numerous sedimentary cycles marked by an alternation of marls and sands are commonly found in the marginal sectors and marls and gypsum in the central sector, which would owe their origins to permanent flooding and evaporation/ re-flooding phases due to global climatic changes. Spectral analyses carried out using Fourier transform have revealed the existence of temporary frequencies associated with sedimentary cycles of between 0.2 and 5.2 ka. The origin of these cycles may be associated with variations in solar radiation and oscillations in the Moons orbital position, which would induce global climatic changes resulting in the rise and fall of the water table of the lake. Autocorrelation analyses conducted separately on the marly and evaporitic levels support this conclusion, as they indicate the existence of significant direct correlations between about 4 to 12 sedimentary cycles, which would correspond to repetitions of the stratigraphic series over a time span of 1.3 to 4 ka. (Author)

Sorption-desorption of imidacloprid onto a lacustrine Egyptian soil and its clay and humic acid fractions.

Science.gov (United States)

Kandil, Mahrous M; El-Aswad, Ahmed F; Koskinen, William C

2015-01-01

Sorption-desorption of the insecticide imidacloprid 1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine onto a lacustrine sandy clay loam Egyptian soil and its clay and humic acid (HA) fractions was investigated in 24-h batch equilibrium experiments. Imidacloprid (IMDA) sorption-desorption isotherms onto the three sorbents were found to belong to a non-linear L-type and were best described by the Freundlich model. The value of the IMDA adsorption distribution coefficient, Kd(ads), varied according to its initial concentration and was ranged 40-84 for HA, 14-58 for clay and 1.85-4.15 for bulk soil. Freundlich sorption coefficient, Kf(ads), values were 63.0, 39.7 and 4.0 for HA, clay and bulk soil, respectively. The normalized soil Koc value for imidacloprid sorption was ∼800 indicating its slight mobility in soils. Nonlinear sorption isotherms were indicated by 1/n(ads) values imidacloprid sorption process with all tested sorbents. Gibbs free energy (ΔG) values indicated a spontaneous and physicosorption process for IMDA and a more favorable sorption to HA than clay and soil. In conclusion, although the humic acid fraction showed the highest capacity and affinity for imidacloprid sorption, the clay fraction contributed to approximately 95% of soil-sorbed insecticide. Clay and humic acid fractions were found to be the major two factors controlling IMDA sorption in soils. The slight mobility of IMDA in soils and the hysteresis phenomenon associated with the irreversibility of its sorption onto, mainly, clay and organic matter of soils make its leachability unlikely to occur.

Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets

Science.gov (United States)

Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd; Schuerer, Anke

2017-06-01

The Bolsena caldera that formed between 0.6 and 0.2 Ma has a well preserved structural rim, which makes it an ideal site to study the tectonic and volcanic evolution of calderas. However, the main area is covered by a 150 m deep lake which makes it rather difficult to investigate the subsurface structure directly. To overcome this problem new high resolution hydro-acoustic surveys using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in September 2012. As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). The subsurface structure of Lake Bolsena was imaged up to a sediment depth of 190 m, which is estimated to have filled over a period of 333 kyrs. However, massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas. Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. We mapped several mound structures at various stratigraphic depths. Two volcanic structures outcrop at the modern lake surface implying recent activity. One of these structures is hardly covered by sediments and has a crater-like feature in its summit. The other structure shows a pockmark-like depression on top. Another observable feature is a partially sediment filled crater located in the western part of the lake which further implies the existence of a magma chamber located beneath the Bolsena caldera. Since the late Pleistocene and Holocene, the sedimentation was mainly hemipelagic evidenced by a sediment drape of up to 10 m thick sediment drape on the uppermost sediments. Beneath the drape we found evidence for a distal tephra layer likely related to an explosive eruption from

Radiometric and Instrumental Neutron Activation Analysis (INAA) of environmental specimens: lacustrine sediments from Danube Delta

International Nuclear Information System (INIS)

Duliu, Octavian G.

2002-01-01

The Danube River is the second most important river of Europe. It has a drainage basin estimated as 817 000 km 2 and caries every year between 35 and 70 megatons of solid matter to the Black Sea, where the discharged sediments are forming the present Danube Delta. The Delta continues to grow seaward at a rate of 25 - 35 meters annually. During its history, the evolution of the Danube Delta was closely connected with Danube's three branches: Chilia (the youngest one) in the North, Sulina in the middle and Sf. Gheorghe (the oldest one) in the South. The fluctuation of both Danube River solid flow and the Blake Sea level determined a significant variability of the sediment composition. Now, these sediments mainly consist of silt, sand, shell debris, etc. Former studies has shown that the sedimentation process, occurring over the entire Delta, is characterized by great variability of the sedimentation rates which takes values between 0.6 mm/year and 100 mm/year. The highest sedimentation rate corresponds to the lakes close to the Danube main branches. Therefore, the total thickness of lacustrine sediments varies between 0.5 m in Matita Lake and 2.5 m to 3 m in Lake Golovita. At the same time, as proven by direct and radiographic investigations, the bottom sediments of almost all lakes of the Danube Delta are intensively bioturbated by the living activity of various invertebrates, such as fresh water mollusks and annelid worms, as well as insects (especially chironomid) larvae which spend their life cycle buried in the mud. Despite their variability, sediments represent a sui generis history of past events across the entire catchment basin of a river. Events that refer to actual or passed history such as pollutants discharge, radioactive contamination, climatic changes, etc., could be retrieved by carefully investigation of vertical profile of both trace elements and artificial as well as natural radionuclides. Radiometric as well as high sensitivity and high

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact approximate to 12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

Czech Academy of Sciences Publication Activity Database

Wolbach, W. S.; Ballard, J. P.; Mayewski, P. A.; Parnell, A. C.; Cahill, N.; Adedeji, V.; Bunch, T. E.; Dominguez-Vazquez, G.; Erlandson, J. M.; Firestone, R. B.; French, T. A.; Howard, G.; Israde-Alcántara, I.; Johnson, J. R.; Kimbel, D.; Kinzie, Ch. R.; Kurbatov, A.; Kletetschka, Günther; LeCompte, M. A.; Mahaney, W. C.; Mellot, A. L.; Mitra, S.; Maiorana-Boutilier, A.; Moore, Ch. R.; Napier, W. M.; Parlier, J.; Tankersley, K. B.; Thomas, B. C.; Wittke, J. H.; West, A.; Kennett, J. P.

2018-01-01

Roč. 126, č. 2 (2018), s. 185-205 ISSN 0022-1376 Institutional support: RVO:67985831 Keywords : biomass burning * climate feedback * climate variation * ice core * lacustrine deposit * marine sediment * paleoclimate * quantitative analysis * terrestrial deposit * winter * Younger Dryas Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 1.952, year: 2016

Variation as a main feature of norm

Directory of Open Access Journals (Sweden)

S. Poladova

2017-09-01

Full Text Available The past half-century has witnessed remarkable growth in the study of language variation, and it has now become a highly productive subfield of research in sociolinguistics. Variability is everywhere in language, from the unique details in each production of a sound or sign to the auditory or visual processing of the linguistic signal. All languages that we can observe today show variation; what is more, they vary in identical ways, namely geographically and socially. It’s no secret that languages like English are full of variation. So, the aim of the article is to detect the reasons of variation and to uncover rates of usage of different free variations for a given set of lexical items. The research work is carried out by using the descriptive, comparative methods by subjecting to analysis the specific language materials. The discovery of law of variation became a starting point for the evolution of linguistics. The problem of search of variation facts and its role in the functioning of language system concerns many specialists from the outset. The scope of the investigation was to set up a system out of chaos of phenomena. Currently, the fact of conditionality of variation by system relations existing in the language is considered to be established.

Evaluation of the long-term evolution of the groundwater system in the Mizunami area, Japan

International Nuclear Information System (INIS)

Mizuno, Takashi; Milodowski, Antoni E.; Iwatsuki, Teruki

2011-01-01

This study aimed to develop a methodology for assessing the evolution of the long-term groundwater system, using fracture-filling calcite. Fracture-filling calcite mineralization in deep (to ca. 1000 m) granitic rocks in Mizunami area, Japan, was studied. Four generations (I to IV) of calcite precipitation can be differentiated based on their paragenetic relationships, morphological and isotopic characteristics. Carbon and oxygen isotopic ratios suggest that the Calcite I is of hydrothermal origin. On the other hand, Calcite II, IV and III were precipitated from freshwater and marine water, respectively. The Mizunami Group strata (Tertiary), which overly the basement Toki granite (Cretaceous), were initially deposited in a lacustrine environment but later became marine. Lacustrine conditions were re-established during the deposition of the upper Seto Group (Quaternary). It is suggested that both of deposition of the marine upper part of the Mizunami Group and the precipitation of Calcite III were possibly related to the same transgression event. This was followed by the precipitation of Calcite IV during subsequent fresh water flushing of the earlier marine groundwater. In summary, integrated morphological, mineralogical, microchemical and isotopic analysis of multilayered calcite fracture mineralization provides valuable information to evaluate the long-term evolution of groundwater system. (author)

Variational integrators in plasma physics

Energy Technology Data Exchange (ETDEWEB)

Kraus, Michael

2013-07-01

To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

Application of the variational iteration method for system of initial value problems delay differential equations

Science.gov (United States)

Yousef, Hamood. M.; Ismail, A. I. B. MD.

2017-08-01

Many attempts have been presented to solve the system of Delay Differential Equations (DDE) with Initial Value Problem. As a result, it has shown difficulties when getting the solution or cannot be solved. In this paper, a Variational Iteration Method is employed to find out an approximate solution for the system of DDE with initial value problems. The example illustrates convenient and an efficiency comparison with the exact solution.

Seasonal variation in the mating system of a selfing annual with large floral displays.

Science.gov (United States)

Yin, Ge; Barrett, Spencer C H; Luo, Yi-Bo; Bai, Wei-Ning

2016-03-01

Flowering plants display considerable variation in mating system, specifically the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season. Here, we investigated seasonal variation in mating and fertility in Incarvillea sinensis (Bignoniaceae), an annual with showy, insect-pollinated, 'one-day' flowers capable of delayed selfing. We examined the influence of several biotic and abiotic environmental factors on day-to-day variation in fruit set, seed set and patterns of mating. We recorded daily flower number and pollinator abundance in nine 3 × 3-m patches in a population at Mu Us Sand land, Inner Mongolia, China. From marked flowers we collected data on daily fruit and seed set and estimated outcrossing rate and biparental inbreeding using six microsatellite loci and 172 open-pollinated families throughout the flowering period. Flower density increased significantly over most of the 50-d flowering season, but was associated with a decline in levels of pollinator service by bees, particularly on windy days. Fruit and seed set declined over time, especially during the latter third of the flowering period. Multilocus estimates of outcrossing rate were obtained using two methods (the programs MLTR and BORICE) and both indicated high selfing rates of ∼80 %. There was evidence for a significant increase in levels of selfing as the flowering season progressed and pollinator visitation declined. Biparental inbreeding also declined significantly as the flowering season progressed. Temporal variation in outcrossing rates may be a common feature of the mating biology of annual, insect-pollinated plants of harsh environments but our study is the first to examine seasonal mating-system dynamics in this context. Despite having large flowers and showy floral displays, I. sinensis attracted relatively few pollinators. Delayed selfing by corolla dragging

Sedimentology and paleoecology of an Eocene Oligocene alluvial lacustrine arid system, Southern Mexico

Science.gov (United States)

Beraldi-Campesi, Hugo; Cevallos-Ferriz, Sergio R. S.; Centeno-García, Elena; Arenas-Abad, Concepción; Fernández, Luis Pedro

2006-10-01

A depositional model of the Eocene-Oligocene Coatzingo Formation in Tepexi de Rodríguez (Puebla, Mexico) is proposed, based on facies analysis of one of the best-preserved sections, the Axamilpa Section. The sedimentary evolution is interpreted as the retrogradation of an alluvial system, followed by the progressive expansion of an alkaline lake system, with deltaic, palustrine, and evaporitic environments. The analysis suggests a change towards more arid conditions with time. Fossils from this region, such as fossil tracks of artiodactyls, aquatic birds and cat-like mammals, suggest that these animals traversed the area, ostracods populated the lake waters, and plants grew on incipient soils and riparian environments many times throughout the history of the basin. The inferred habitat for some fossil plants coincides with the sedimentological interpretation of an arid to semiarid climate for that epoch. This combined sedimentological-paleontological study of the Axamilpa Section provides an environmental context in which fossils can be placed and brings into attention important biotic episodes, like bird and camelid migrations or the origin of endemic but extinct plants in this area.

Variational coupling between q-number and c-number dynamics

International Nuclear Information System (INIS)

Amaral, C.M. do; Joffily, S.

1984-01-01

The time-dependent quantum variational principle is generalized for the case of hamiltonian operators having real parameters and their time derivates. The obtained variational system is formed by a Schroedinger equation coupled to a Lagrange equation system, where the lagrangian is the average value of the parametrized hamiltonian operator. The consequent dynamics of the variational principle, describes the interaction between a q-number sub-dynamics with a c-number sub-dynamics. In the ((h/2π)) 0 -order W.K.B. approximation, the variational system reduces to a Hamilton-Jacobi-like equation, coupled to a Lagrange equation family. The formal features of the obtained variational system are appropriated for the description of, adiabatics and non-adiabatics, time-dependent q-number c-number interactions. (L.C.) [pt

Mineralogy of Fluvio-Lacustrine Sediments Investigated by Curiosity During the Prime Mission: Implications for Diagenesis

Science.gov (United States)

Rampe, Elizabeth B.; Morris, R. V.; Bish, D. L.; Vaniman, D. T.; Bristow, T. F.; Chipera, S. J.; Blake, D. F.; Ming, D. W.; Farmer, J. D.; Morrison, S. M.;

THE EVIL-MC MODEL FOR ELLIPSOIDAL VARIATIONS OF PLANET-HOSTING STARS AND APPLICATIONS TO THE HAT-P-7 SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Jackson, Brian K. [Carnegie Institution for Science, Washington, DC 20015 (United States); Lewis, Nikole K.; Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Kuiper Space Sciences Building, Tucson, AZ 85721 (United States); Barnes, Jason W. [Department of Physics, University of Idaho, Engineering-Physics Building, Moscow, ID 83844 (United States); Deming, L. Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Fortney, Jonathan J., E-mail: bjackson@dtm.ciw.edu [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

2012-06-01

We present a new model for Ellipsoidal Variations Induced by a Low-Mass Companion, the EVIL-MC model. We employ several approximations appropriate for planetary systems to substantially increase the computational efficiency of our model relative to more general ellipsoidal variation models and improve upon the accuracy of simpler models. This new approach gives us a unique ability to rapidly and accurately determine planetary system parameters. We use the EVIL-MC model to analyze Kepler Quarter 0-2 (Q0-2) observations of the HAT-P-7 system, an F-type star orbited by a {approx} Jupiter-mass companion. Our analysis corroborates previous estimates of the planet-star mass ratio q = (1.10 {+-} 0.06) Multiplication-Sign 10{sup -3}, and we have revised the planet's dayside brightness temperature to 2680{sup +10}{sub -20} K. We also find a large difference between the day- and nightside planetary flux, with little nightside emission. Preliminary dynamical+radiative modeling of the atmosphere indicates that this result is qualitatively consistent with high altitude absorption of stellar heating. Similar analyses of Kepler and CoRoT photometry of other planets using EVIL-MC will play a key role in providing constraints on the properties of many extrasolar systems, especially given the limited resources for follow-up and characterization of these systems. However, as we highlight, there are important degeneracies between the contributions from ellipsoidal variations and planetary emission and reflection. Consequently, for many of the hottest and brightest Kepler and CoRoT planets, accurate estimates of the planetary emission and reflection, diagnostic of atmospheric heat budgets, will require accurate modeling of the photometric contribution from the stellar ellipsoidal variation.

El sistema lacustre de la Formación Mollar en el depocentro triásico de Santa Clara (provincia de Mendoza, Argentina The lacustrine system of the Mollar Formation in the Triassic Santa Clara Depocenter (Mendoza Province, Argentina

Directory of Open Access Journals (Sweden)

Luis A Spalletti

2009-07-01

depocentro de Santa Clara a medida que se produjo la acumulación de los depósitos estudiados.The Triassic Santa Clara depocenter, Cuyo Basin, is characterised by thick fine-grained deposits formed in lacustrine systems. One of them, represented by the Mollar Formation, exceeds the 345 m. The lower to middle section of this unit is dominated by a monotonous succession of black shales having a high content of amorphous organic matter produced by algae and highly degraded plant remains. These deposits were formed by suspensión fallout in the anoxic 'offshore' sector of a hydrologically closed lake. Thin and fine-grained turbiditic beds and stromatolitic carbonates are intercalated in the fine-grained succession. Small-scale coarsening-upward cycles (PACs are attributed to episodes of lake expansion-retraction driven by climate change. A facies association composed of an heterolithic package represents the deposits of the transition between 'nearshore' and 'offshore' settings. The upper section of the Mollar Formation essentially consists of bioturbated mudstones suggesting a greater oxygenation of the substrate. They are assigned to the 'offshore' environment of a holomictic hydrologically open lake system. Sporadic hyperpycnal flows are documented by intercalations of sandy turbidites. Bioturbated sandstone beds with primary structures indicative of both normal and storm wave action and unidirectional flows, represent the marginal deposits of the lacustrine system. In addition to the high-frequency cycles, three larger scale asymmetrical sequences are identified in the Mollar Formation. These sequences suggest episodes of major expansion-contraction of the lake system due to the interaction between climatic and tectonic factors. The overall shallowing up stacking pattern of the Mollar Formation and the gradual transition to fluvial deposits of the overlying Montaña Formation reflects a steady reduction of accommodation space in the Santa Clara depocenter during the

Variations of Hodge Structure Considered as an Exterior Differential System: Old and New Results

Directory of Open Access Journals (Sweden)

James Carlson

2009-09-01

Full Text Available This paper is a survey of the subject of variations of Hodge structure (VHS considered as exterior differential systems (EDS. We review developments over the last twenty-six years, with an emphasis on some key examples. In the penultimate section we present some new results on the characteristic cohomology of a homogeneous Pfaffian system. In the last section we discuss how the integrability conditions of an EDS affect the expected dimension of an integral submanifold. The paper ends with some speculation on EDS and Hodge conjecture for Calabi-Yau manifolds.

Variational study of fermionic and bosonic systems with non-Gaussian states: Theory and applications

Science.gov (United States)

Shi, Tao; Demler, Eugene; Ignacio Cirac, J.

2018-03-01

We present a new variational method for investigating the ground state and out of equilibrium dynamics of quantum many-body bosonic and fermionic systems. Our approach is based on constructing variational wavefunctions which extend Gaussian states by including generalized canonical transformations between the fields. The key advantage of such states compared to simple Gaussian states is presence of non-factorizable correlations and the possibility of describing states with strong entanglement between particles. In contrast to the commonly used canonical transformations, such as the polaron or Lang-Firsov transformations, we allow parameters of the transformations to be time dependent, which extends their regions of applicability. We derive equations of motion for the parameters characterizing the states both in real and imaginary time using the differential structure of the variational manifold. The ground state can be found by following the imaginary time evolution until it converges to a steady state. Collective excitations in the system can be obtained by linearizing the real-time equations of motion in the vicinity of the imaginary time steady-state solution. Our formalism allows us not only to determine the energy spectrum of quasiparticles and their lifetime, but to obtain the complete spectral functions and to explore far out of equilibrium dynamics such as coherent evolution following a quantum quench. We illustrate and benchmark this framework with several examples: a single polaron in the Holstein and Su-Schrieffer-Heeger models, non-equilibrium dynamics in the spin-boson and Kondo models, the superconducting to charge density wave phase transitions in the Holstein model.

The benefit of accounting for DQE variations in simulated dose reduction of digital radiographic systems

International Nuclear Information System (INIS)

Svalkvist, A.; Baath, M.

2010-01-01

Adding noise to clinical radiographs to simulate dose reduction can be used to investigate the relationship between dose level and clinical image quality without exposing patients to additional radiation. The purpose of the present paper was to examine the benefits of using a method that accounts for detective quantum efficiency (DQE) variations that may occur in different dose ranges in the simulated dose reduction process. A method initially intended for simulated dose reduction in tomo-synthesis was applied to extremely low-dose posterio-anterior radiographs of an anthropomorphic chest phantom, selected from a group of projection images included in a tomo-synthesis examination and compared with a previous method that do not account for DQE variations. A comparison of images simulated to be collected at a lower dose level (73% of the original dose level) and images actually collected at this lower dose level revealed that the error in the integrated normalised noise power spectrum was smaller than 4% for the method that accounts for DQE variations in the simulated dose reduction, whereas the error was larger than 20% for the previous method. This indicates that an increased validity in dose reduction simulation of digital radiographic systems is obtained with a method accounting for DQE variations. (authors)

Image correction during large and rapid B(0) variations in an open MRI system with permanent magnets using navigator echoes and phase compensation.

Science.gov (United States)

Li, Jianqi; Wang, Yi; Jiang, Yu; Xie, Haibin; Li, Gengying

2009-09-01

An open permanent magnet system with vertical B(0) field and without self-shielding can be quite susceptible to perturbations from external magnetic sources. B(0) variation in such a system located close to a subway station was measured to be greater than 0.7 microT by both MRI and a fluxgate magnetometer. This B(0) variation caused image artifacts. A navigator echo approach that monitored and compensated the view-to-view variation in magnetic resonance signal phase was developed to correct for image artifacts. Human brain imaging experiments using a multislice gradient-echo sequence demonstrated that the ghosting and blurring artifacts associated with B(0) variations were effectively removed using the navigator method.

Geology and photometric variation of solar system bodies with minor atmospheres: implications for solid exoplanets.

Science.gov (United States)

Fujii, Yuka; Kimura, Jun; Dohm, James; Ohtake, Makiko

2014-09-01

A reasonable basis for future astronomical investigations of exoplanets lies in our best knowledge of the planets and satellites in the Solar System. Solar System bodies exhibit a wide variety of surface environments, even including potential habitable conditions beyond Earth, and it is essential to know how they can be characterized from outside the Solar System. In this study, we provide an overview of geological features of major Solar System solid bodies with minor atmospheres (i.e., the terrestrial Moon, Mercury, the Galilean moons, and Mars) that affect surface albedo at local to global scale, and we survey how they influence point-source photometry in the UV/visible/near IR (i.e., the reflection-dominant range). We simulate them based on recent mapping products and also compile observed light curves where available. We show a 5-50% peak-to-trough variation amplitude in one spin rotation associated with various geological processes including heterogeneous surface compositions due to igneous activities, interaction with surrounding energetic particles, and distribution of grained materials. Some indications of these processes are provided by the amplitude and wavelength dependence of variation in combinations of the time-averaged spectra. We also estimate the photometric precision needed to detect their spin rotation rates through periodogram analysis. Our survey illustrates realistic possibilities for inferring the detailed properties of solid exoplanets with future direct imaging observations. Key Words: Planetary environments-Planetary geology-Solar System-Extrasolar terrestrial planets.

Reduce in Variation and Improve Efficiency of Target Volume Delineation by a Computer-Assisted System Using a Deformable Image Registration Approach

International Nuclear Information System (INIS)

Chao, K.S. Clifford; Bhide, Shreerang FRCR; Chen, Hansen; Asper, Joshua PAC; Bush, Steven; Franklin, Gregg; Kavadi, Vivek; Liengswangwong, Vichaivood; Gordon, William; Raben, Adam; Strasser, Jon; Koprowski, Christopher; Frank, Steven; Chronowski, Gregory; Ahamad, Anesa; Malyapa, Robert; Zhang Lifei; Dong Lei

2007-01-01

Purpose: To determine whether a computer-assisted target volume delineation (CAT) system using a deformable image registration approach can reduce the variation of target delineation among physicians with different head and neck (HN) IMRT experiences and reduce the time spent on the contouring process. Materials and Methods: We developed a deformable image registration method for mapping contours from a template case to a patient case with a similar tumor manifestation but different body configuration. Eight radiation oncologists with varying levels of clinical experience in HN IMRT performed target delineation on two HN cases, one with base-of-tongue (BOT) cancer and another with nasopharyngeal cancer (NPC), by first contouring from scratch and then by modifying the contours deformed by the CAT system. The gross target volumes were provided. Regions of interest for comparison included the clinical target volumes (CTVs) and normal organs. The volumetric and geometric variation of these regions of interest and the time spent on contouring were analyzed. Results: We found that the variation in delineating CTVs from scratch among the physicians was significant, and that using the CAT system reduced volumetric variation and improved geometric consistency in both BOT and NPC cases. The average timesaving when using the CAT system was 26% to 29% for more experienced physicians and 38% to 47% for the less experienced ones. Conclusions: A computer-assisted target volume delineation approach, using a deformable image-registration method with template contours, was able to reduce the variation among physicians with different experiences in HN IMRT while saving contouring time

Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system

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D Manzoori

2009-12-01

Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes Δ B and Δ V, along with corresponding values of Δ(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period

Ensembl variation resources

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Marin-Garcia Pablo

2010-05-01

Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.

Variational calculus with constraints on general algebroids

Energy Technology Data Exchange (ETDEWEB)

Grabowska, Katarzyna [Physics Department, Division of Mathematical Methods in Physics, University of Warsaw, Hoza 69, 00-681 Warszawa (Poland); Grabowski, Janusz [Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, PO Box 21, 00-956 Warszawa (Poland)], E-mail: konieczn@fuw.edu.pl, E-mail: jagrab@impan.gov.pl

2008-05-02

Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM.

Variational calculus with constraints on general algebroids

International Nuclear Information System (INIS)

Grabowska, Katarzyna; Grabowski, Janusz

2008-01-01

Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM

The response of deltaic systems to climatic and hydrological changes in Daihai Lake rift basin, Inner Mongolia, northern China

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Yu Xinghe

2013-01-01

Full Text Available Delta systems are ubiquitous around lacustrine rift basins. Its peripheral geometry, progradation structures and sedimentary successions were controlled by both tectonic settings and climatic changes. Peripheral geometry of a delta was strongly influenced by depositional gradients which formed the fan-shape delta on the steep slopes and developed the lobe-shape delta on the gentle slopes. Due to the discharge feed rivers can change rapidly driven by climatic variations, and the nearshore area of deltas display considerable facies variability. The rise of annual rainfall, which suggests the rivers feeding deltas are continuous, and result in distributary mouth bars that are prevalent in the front of deltas since the down-slope flows are greater than the along-slope currents. On the contrary, when the annual rainfall decreases and evaporation increases, the rivers only can feed deltas ephemerally. If the along-slope currents were in a dominant position, the distal bars were deposited. Progradation structure and sedimentary successions of deltas were controlled by the gradients of slopes. On gentle depositional slopes, shingle foreset beds predominate with fine sediments and small-scale sedimentary structures or vice versa.

Lowest-order constrained variational method for simple many-fermion systems

International Nuclear Information System (INIS)

Alexandrov, I.; Moszkowski, S.A.; Wong, C.W.

1975-01-01

The authors study the potential energy of many-fermion systems calculated by the lowest-order constrained variational (LOCV) method of Pandharipande. Two simple two-body interactions are used. For a simple hard-core potential in a dilute Fermi gas, they find that the Huang-Yang exclusion correction can be used to determine a healing distance. The result is close to the older Pandharipande prescription for the healing distance. For a hard core plus attractive exponential potential, the LOCV result agrees closely with the lowest-order separation method of Moszkowski and Scott. They find that the LOCV result has a shallow minimum as a function of the healing distance at the Moszkowski-Scott separation distance. The significance of the absence of a Brueckner dispersion correction in the LOCV result is discussed. (Auth.)

A variational Bayesian multiple particle filtering scheme for large-dimensional systems

KAUST Repository

Ait-El-Fquih, Boujemaa

2016-06-14

This paper considers the Bayesian filtering problem in high-dimensional nonlinear state-space systems. In such systems, classical particle filters (PFs) are impractical due to the prohibitive number of required particles to obtain reasonable performances. One approach that has been introduced to overcome this problem is the concept of multiple PFs (MPFs), where the state-space is split into low-dimensional subspaces and then a separate PF is applied to each subspace. Remarkable performances of MPF-like filters motivated our investigation here into a new strategy that combines the variational Bayesian approach to split the state-space with random sampling techniques, to derive a new computationally efficient MPF. The propagation of each particle in the prediction step of the resulting filter requires generating only a single particle in contrast with standard MPFs, for which a set of (children) particles is required. We present simulation results to evaluate the behavior of the proposed filter and compare its performances against standard PF and a MPF.

A variational Bayesian multiple particle filtering scheme for large-dimensional systems

KAUST Repository

Ait-El-Fquih, Boujemaa; Hoteit, Ibrahim

2016-01-01

This paper considers the Bayesian filtering problem in high-dimensional nonlinear state-space systems. In such systems, classical particle filters (PFs) are impractical due to the prohibitive number of required particles to obtain reasonable performances. One approach that has been introduced to overcome this problem is the concept of multiple PFs (MPFs), where the state-space is split into low-dimensional subspaces and then a separate PF is applied to each subspace. Remarkable performances of MPF-like filters motivated our investigation here into a new strategy that combines the variational Bayesian approach to split the state-space with random sampling techniques, to derive a new computationally efficient MPF. The propagation of each particle in the prediction step of the resulting filter requires generating only a single particle in contrast with standard MPFs, for which a set of (children) particles is required. We present simulation results to evaluate the behavior of the proposed filter and compare its performances against standard PF and a MPF.

Depositional environments and cyclo- and chronostratigraphy of uppermost Carboniferous-Lower Triassic -lacustrine deposits, southern Bogda Mountains, NW China - A terrestrfluvialial paleoclimatic record of mid-latitude NE Pangea

Science.gov (United States)

Yang, W.; Feng, Q.; Liu, Yajing; Tabor, N.; Miggins, D.; Crowley, J.L.; Lin, J.; Thomas, S.

2010-01-01

Two uppermost Carboniferous–Lower Triassic fluvial–lacustrine sections in the Tarlong–Taodonggou half-graben, southern Bogda Mountains, NW China, comprise a 1834 m-thick, relatively complete sedimentary and paleoclimatic record of the east coast of mid-latitude NE Pangea. Depositional environmental interpretations identified three orders (high, intermediate, and low) of sedimentary cycles. High-order cycles (HCs) have five basic types, including fluvial cycles recording repetitive changes of erosion and deposition and lacustrine cycles recording repetitive environmental changes associated with lake expansion and contraction. HCs are grouped into intermediate-order cycles (ICs) on the basis of systematic changes of thickness, type, and component lithofacies of HCs. Nine low-order cycles (LCs) are demarcated by graben-wide surfaces across which significant long-term environmental changes occurred. A preliminary cyclostratigraphic framework provides a foundation for future studies of terrestrial climate, tectonics, and paleontology in mid-latitude NE Pangea.Climate variabilities at the intra-HC, HC, IC, and LC scales were interpreted from sedimentary and paleosol evidence. Four prominent climatic shifts are present: 1) from the humid–subhumid to highly-variable subhumid–semiarid conditions at the beginning of Sakamarian; 2) from highly-variable subhumid–semiarid to humid–subhumid conditions across the Artinskian-Capitanian unconformity; 3) from humid–subhumid to highly-variable subhumid–semiarid conditions at early Induan; and 4) from the highly-variable subhumid–semiarid to humid–subhumid conditions across the Olenekian-Anisian unconformity. The stable humid–subhumid condition from Lopingian to early Induan implies that paleoclimate change may not have been the cause of the end-Permian terrestrial mass extinction. A close documentation of the pace and timing of the extinction and exploration of other causes are needed. In addition, the

Multi-Scale Three-Dimensional Variational Data Assimilation System for Coastal Ocean Prediction

Science.gov (United States)

Li, Zhijin; Chao, Yi; Li, P. Peggy

2012-01-01

A multi-scale three-dimensional variational data assimilation system (MS-3DVAR) has been formulated and the associated software system has been developed for improving high-resolution coastal ocean prediction. This system helps improve coastal ocean prediction skill, and has been used in support of operational coastal ocean forecasting systems and field experiments. The system has been developed to improve the capability of data assimilation for assimilating, simultaneously and effectively, sparse vertical profiles and high-resolution remote sensing surface measurements into coastal ocean models, as well as constraining model biases. In this system, the cost function is decomposed into two separate units for the large- and small-scale components, respectively. As such, data assimilation is implemented sequentially from large to small scales, the background error covariance is constructed to be scale-dependent, and a scale-dependent dynamic balance is incorporated. This scheme then allows effective constraining large scales and model bias through assimilating sparse vertical profiles, and small scales through assimilating high-resolution surface measurements. This MS-3DVAR enhances the capability of the traditional 3DVAR for assimilating highly heterogeneously distributed observations, such as along-track satellite altimetry data, and particularly maximizing the extraction of information from limited numbers of vertical profile observations.

Application of Method of Variation to Analyze and Predict Human Induced Modifications of Water Resource Systems

Science.gov (United States)

Dessu, S. B.; Melesse, A. M.; Mahadev, B.; McClain, M.

2010-12-01

Water resource systems have often used gravitational surface and subsurface flows because of their practicality in hydrological modeling and prediction. Activities such as inter/intra-basin water transfer, the use of small pumps and the construction of micro-ponds challenge the tradition of natural rivers as water resource management unit. On the contrary, precipitation is barely affected by topography and plot harvesting in wet regions can be more manageable than diverting from rivers. Therefore, it is indicative to attend to systems where precipitation drives the dynamics while the internal mechanics constitutes spectrum of human activity and decision in a network of plots. The trade-in volume and path of harvested precipitation depends on water balance, energy balance and the kinematics of supply and demand. Method of variation can be used to understand and predict the implication of local excess precipitation harvest and exchange on the natural water system. A system model was developed using the variational form of Euler-Bernoulli’s equation for the Kenyan Mara River basin. Satellite derived digital elevation models, precipitation estimates, and surface properties such as fractional impervious surface area, are used to estimate the available water resource. Four management conditions are imposed in the model: gravitational flow, open water extraction and high water use investment at upstream and downstream respectively. According to the model, the first management maintains the basin status quo while the open source management could induce externality. The high water market at the upstream in the third management offers more than 50% of the basin-wide total revenue to the upper third section of the basin thus may promote more harvesting. The open source and upstream exploitation suggest potential drop of water availability to downstream. The model exposed the latent potential of economic gradient to reconfigure the flow network along the direction where the

Holocene moisture variations over the arid central Asia revealed by a comprehensive sand-dune record from the central Tian Shan, NW China

Science.gov (United States)

Long, Hao; Shen, Ji; Chen, Jianhui; Tsukamoto, Sumiko; Yang, Linhai; Cheng, Hongyi; Frechen, Manfred

2017-10-01

Arid central Asia (ACA) is one of the largest arid (desert) areas in the world, and its climate is dominated by the westerlies. In this study, we examined sand dune evolution from the Bayanbulak Basin in the Tian Shan (Xinjiang, NW China), aiming to infer the Holocene moisture history of the ACA. Combined with stratigraphic observation and environmental proxies analysis (grain size, magnetic susceptibility and total organic content), large numbers of luminescence ages from multiple sites (eight sections, 79 samples) were applied to reconstruct the evolution of the sand dune accumulation in the study basin. The overall results imply very dry conditions characterized by sand dune accumulation at ∼12-6.5 ka, a wet interval between ∼6.5 and 0.8 ka when soil formation occurred, and decreased moisture during the last 0.8 ka. This moisture variation pattern is generally consistent with that inferred from many lacustrine records in the core zone of ACA, suggesting a widespread dry period in the early-to-middle Holocene and relatively wet middle-to-late Holocene. Thus, the moisture history derived from the current sand dune system contrasts with that in Asian monsoon areas, which are characterized by a strong monsoon (high precipitation) in the early and mid-Holocene and a weak monsoon (low precipitation and dry climate) during the late Holocene. Our results strongly suggest that the winter solar insolation and the external boundary conditions such as atmospheric CO2 concentration, ice sheets, and meltwater fluxes, have been major influential factors triggering the Holocene moisture evolution in the core zone of ACA.

Temporal variations in the potential hydrological performance of extensive green roof systems

Science.gov (United States)

De-Ville, Simon; Menon, Manoj; Stovin, Virginia

2018-03-01

Existing literature provides contradictory information about variation in potential green roof hydrological performance over time. This study has evaluated a long-term hydrological monitoring record from a series of extensive green roof test beds to identify long-term evolutions and sub-annual (seasonal) variations in potential hydrological performance. Monitoring of nine differently-configured extensive green roof test beds took place over a period of 6 years in Sheffield, UK. Long-term evolutions and sub-annual trends in maximum potential retention performance were identified through physical monitoring of substrate field capacity over time. An independent evaluation of temporal variations in detention performance was undertaken through the fitting of reservoir-routing model parameters. Aggregation of the resulting retention and detention variations permitted the prediction of extensive green roof hydrological performance in response to a 1-in-30-year 1-h summer design storm for Sheffield, UK, which facilitated the comparison of multi and sub-annual hydrological performance variations. Sub-annual (seasonal) variation was found to be significantly greater than long-term evolution. Potential retention performance increased by up to 12% after 5-years, whilst the maximum sub-annual variation in potential retention was 27%. For vegetated roof configurations, a 4% long-term improvement was observed for detention performance, compared to a maximum 63% sub-annual variation. Consistent long-term reductions in detention performance were observed in unvegetated roof configurations, with a non-standard expanded-clay substrate experiencing a 45% reduction in peak attenuation over 5-years. Conventional roof configurations exhibit stable long-term hydrological performance, but are nonetheless subject to sub-annual variation.

A case for variational geomagnetic data assimilation: insights from a one-dimensional, nonlinear, and sparsely observed MHD system

Directory of Open Access Journals (Sweden)

A. Fournier

2007-01-01

Full Text Available Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during the last few hundred years, culminating nowadays with satellite data. It is however well known that the dynamics of the magnetic field is linked to that of the velocity field in the core and any attempt to model secular variations will involve a coupled dynamical system for magnetic field and core velocity. Unfortunately, there is no direct observation of the velocity. Independently of the exact nature of the above-mentioned coupled system – some version being currently under construction – the question is debated in this paper whether good knowledge of the magnetic field can be translated into good knowledge of core dynamics. Furthermore, what will be the impact of the most recent and precise geomagnetic data on our knowledge of the geomagnetic field of the past and future? These questions are cast into the language of variational data assimilation, while the dynamical system considered in this paper consists in a set of two oversimplified one-dimensional equations for magnetic and velocity fields. This toy model retains important features inherited from the induction and Navier-Stokes equations: non-linear magnetic and momentum terms are present and its linear response to small disturbances contains Alfvén waves. It is concluded that variational data assimilation is indeed appropriate in principle, even though the velocity field remains hidden at all times; it allows us to recover the entire evolution of both fields from partial and irregularly distributed information on the magnetic field. This work constitutes a first step on the way toward the reassimilation of historical geomagnetic data and geomagnetic forecast.

High resolution HH-XRF scanning and XRD modelling as a tool in sedimentological analysis - A case study from the Enreca-3 core, Bach Long Vi Island, Vietnam

Science.gov (United States)

Rizzi, Malgorzata; Hemmingsen Schovsbo, Niels; Korte, Christoph; Bryld Wessel Fyhn, Michael

2017-04-01

To improve the understanding and interpretation of the depositional environment of a late Oligocene lacustrine organic rich oil-prone source rock succession, 2464 hand held (HH)-XRF measurements were made systematically on the 500 m long, continuous core from the fully cored Enreca-3 well. This core, drilled on the remote Bach Long Vi Island, northern Gulf of Tonkin, offshore Vietnam, represents a deep lake succession alternating between lacustrine pelagic dominated sediments interrupted by hyperpycnal turbidites, high density turbidites and debris flows [1, 2]. From a combined HH-XRF-XRD data set, multivariate data analysis and regression models are used to type the rock and to predict the XRD mineral composition based on HH-XRF composition. The rock types and the modelled mineral composition highlight the geochemical variations of the sediment and allows for direct comparison with sedimentological processes and facies changes. The modeling also depicts the cyclic alteration of rock types that are present on many different scales ranging from centimeters to hundreds of meters [1, 2]. The sedimentological and geochemical variations observed throughout the cored section reflects fluctuating paleoclimate, tectonism and hinterland condition controlling the depositional setting, which may provide a deeper understanding of the deposition of this and similar Paleogene syn-rift succession in the South China Sea region. It allows furthermore the development of a more generalized depositional model relevant for other deep-lacustrine syn-rift basins. [1] Petersen et al. (2014) Journal of Petroleum Geology, 37: 373-389. [2] Hovikoski et al. (2016) Journal of Sedimentary Research, 86(8): 982-1007.

Existence of evolutionary variational solutions via the calculus of variations

Science.gov (United States)

Bögelein, Verena; Duzaar, Frank; Marcellini, Paolo

In this paper we introduce a purely variational approach to time dependent problems, yielding the existence of global parabolic minimizers, that is ∫0T ∫Ω [uṡ∂tφ+f(x,Du)] dx dt⩽∫0T ∫Ω f(x,Du+Dφ) dx dt, whenever T>0 and φ∈C0∞(Ω×(0,T),RN). For the integrand f:Ω×R→[0,∞] we merely assume convexity with respect to the gradient variable and coercivity. These evolutionary variational solutions are obtained as limits of maps depending on space and time minimizing certain convex variational functionals. In the simplest situation, with some growth conditions on f, the method provides the existence of global weak solutions to Cauchy-Dirichlet problems of parabolic systems of the type ∂tu-divDξf(x,Du)=0 in Ω×(0,∞).

Neoglacial fluctuations of terrestrial, tidewater, and calving lacustrine glaciers, Blackstone-Spencer Ice Complex, Kenai Mountains, Alaska

Science.gov (United States)

Crossen, Kristine June

1997-12-01

The glaciers surrounding the Blackstone-Spencer Ice Complex display a variety of termini types: Tebenkov, Spencer, Bartlett, Skookum, Trail, Burns, Shakespeare, Marquette, Lawrence, and Ripon glaciers end in terrestrial margins; Blackstone and Beloit glaciers have tidewater termini; and Portage Glacier has a calving lacustrine margin. In addition, steep temperature and precipitation gradients exist across the ice complex from the maritime environment of Prince William Sound to the colder, drier interior. The Neoglacial history of Tebenkov Glacier, as based on overrun trees near the terminus, shows advances ca. 250- 430 AD (calibrated date), ca. 1215-1275 AD (calibrated date), and ca. 1320-1430 AD (tree ring evidence), all intervals of glacier advance around the Gulf of Alaska. However, two tidewater glaciers in Blackstone Bay retreated from their outermost moraines by 1350 AD, apparently asynchronously with respect to the regional climate signal. The most extensive Kenai Mountain glacier expansions during Neoglaciation occurred in the late Little Ice Age. The outermost moraines are adjacent to mature forest stands and bog peats that yield dates as old as 5,600 BP. Prince William Sound glaciers advanced during two Little Ice Age cold periods, 1380-1680 and 1830-1900 AD. The terrestrial glaciers around the Blackstone-Spencer Ice Complex all built moraines during the 19th century and began retreating between 1875 and 1900 AD. Portage and Burns glaciers began retreating between 1790 and 1810 AD, but their margins remained close to the outermost moraines during the 19th century. Regional glacier fluctuations are broadly synchronous in the Gulf of Alaska region. With the exception of the two tidewater glaciers in Blackstone Bay, all glaciers in the Kenai Mountains, no matter their sizes, altitudes, orientations, or types of margins, retreated at the end of the Little Ice Age. The climate signal, especially temperature, appears to be the strongest control on glacier

Impacts of flamingos on saline lake margin and shallow lacustrine sediments in the Kenya Rift Valley

Science.gov (United States)

Scott, Jennifer J.; Renaut, Robin W.; Owen, R. Bernhart

2012-11-01

Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~ 9 cm long, ~ 11 cm wide) and nest mounds (~ 30 cm wide, ~ 20 cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~ 0.5-2 cm in diameter), pinched, 'bubble pores' and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding 'body' of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine

Generalization of the variational principle and the Hohenberg and Kohn theorems for excited states of Fermion systems

Energy Technology Data Exchange (ETDEWEB)

Gonis, A., E-mail: gonis@comcast.net

2017-01-05

Through the entanglement of a collection of K non-interacting replicas of a system of N interacting Fermions, and making use of the properties of reduced density matrices the variational principle and the theorems of Hohenberg and Kohn are generalized to excited states. The generalization of the variational principle makes use of the natural orbitals of an N-particle density matrix describing the state of lowest energy of the entangled state. The extension of the theorems of Hohenberg and Kohn is based on the ground-state formulation of density functional theory but with a new interpretation of the concept of a ground state: It is the state of lowest energy of a system of KN Fermions that is described in terms of the excited states of the N-particle interacting system. This straightforward implementation of the line of reasoning of ground-state density functional theory to a new domain leads to a unique and logically valid extension of the theory to excited states that allows the systematic treatment of all states in the spectrum of the Hamiltonian of an interacting system. - Highlights: • Use of entanglement in connection with the properties of density matrices. • An anti-symmetric entangled state of order KN expressed in terms of excited states of an interacting N-particle system.

Variation Tolerant On-Chip Interconnects

CERN Document Server

Nigussie, Ethiopia Enideg

2012-01-01

This book presents design techniques, analysis and implementation of high performance and power efficient, variation tolerant on-chip interconnects.  Given the design paradigm shift to multi-core, interconnect-centric designs and the increase in sources of variability and their impact in sub-100nm technologies, this book will be an invaluable reference for anyone concerned with the design of next generation, high-performance electronics systems. Provides comprehensive, circuit-level explanation of high-performance, energy-efficient, variation-tolerant on-chip interconnect; Describes design techniques to mitigate problems caused by variation; Includes techniques for design and implementation of self-timed on-chip interconnect, delay variation insensitive communication protocols, high speed signaling techniques and circuits, bit-width independent completion detection and process, voltage and temperature variation tolerance.                          

Effect of Different Solar Radiation Data Sources on the Variation of Techno-Economic Feasibility of PV Power System

Science.gov (United States)

Alghoul, M. A.; Ali, Amer; Kannanaikal, F. V.; Amin, N.; Aljaafar, A. A.; Kadhim, Mohammed; Sopian, K.

2017-11-01

The aim of this study is to evaluate the variation in techno-economic feasibility of PV power system under different data sources of solar radiation. HOMER simulation tool is used to predict the techno-economic feasibility parameters of PV power system in Baghdad city, Iraq located at (33.3128° N, 44.3615° E) as a case study. Four data sources of solar radiation, different annual capacity shortages percentage (0, 2.5, 5, and 7.5), and wide range of daily load profile (10-100 kWh/day) are implemented. The analyzed parameters of the techno-economic feasibility are COE (/kWh), PV array power capacity (kW), PV electrical production (kWh/year), No. of batteries and battery lifetime (year). The main results of the study revealed the followings: (1) solar radiation from different data sources caused observed to significant variation in the values of the techno-economic feasibility parameters; therefore, careful attention must be paid to ensure the use of an accurate solar input data; (2) Average solar radiation from different data sources can be recommended as a reasonable input data; (3) it is observed that as the size and of PV power system increases, the effect of different data sources of solar radiation increases and causes significant variation in the values of the techno-economic feasibility parameters.

Spatiotemporal dynamics of the bacterial microbiota on lacustrine Cladophora glomerata (Chlorophyta).

Science.gov (United States)

Braus, Michael J; Graham, Linda E; Whitman, Thea L

2017-12-01

The branched periphytic green alga Cladophora glomerata, often abundant in nearshore waters of lakes and rivers worldwide, plays important ecosystem roles, some mediated by epibiotic microbiota that benefit from host-provided surface, organic C, and O 2 . Previous microscopy and high-throughput sequencing studies have indicated surprising epibiont taxonomic and functional diversity, but have not included adequate consideration of sample replication or the potential for spatial and temporal variation. Here, we report the results of 16S rRNA amplicon-based phylum-to-genus taxonomic analysis of Cladophora-associated bacterial epibiota sampled in replicate from three microsites and at six times during the open-water season of 2014, from the same lake locale (Picnic Point, Lake Mendota, Dane Co., WI, USA) explored by high-throughput sequencing studies in two previous years. Statistical methods were used to test null hypotheses that the bacterial community: (i) is homogeneous across microsites tested, and (ii) does not change over the course of a growth season or among successive years. Results indicated a dynamic microbial community that is more strongly influenced by sampling day during the growth season than by microsite variation. A surprising diversity of bacterial genera known to be associated with the key function of methane-oxidation (methanotrophy), including relatively high-abundance of Crenothrix, Methylomonas, Methylovulum, and Methylocaldum-showed intraseasonal and interannual variability possibly related to temperature differences, and microsite preferences possibly related to variation in methane abundance. By contrast, a core assemblage of bacterial genera seems to persist over a growth season and from year to year, possibly transmitted by a persistent attached host resting stage. © 2017 Phycological Society of America.

Parkinson's disease and mitochondrial gene variations

DEFF Research Database (Denmark)

Andalib, Sasan; Vafaee, Manouchehr Seyedi; Gjedde, Albert

2014-01-01

Parkinson's disease (PD) is a common disorder of the central nervous system in the elderly. The pathogenesis of PD is a complex process, with genetics as an important contributing factor. This factor may stem from mitochondrial gene variations and mutations as well as from nuclear gene variations...

a Study of the Impact of Doubling Carbon Dioxide and Solar Radiation Variations on the Climate System.

Science.gov (United States)

Chu, Shaoping

The exchange of moisture and heat between the atmosphere and the Earth's surface fundamentally affect the dynamics and thermodynamics of the climate system. In order to trace moisture flow through the climate system and examine its impact on climate, a hydrologic cycle and a land energy balance have been developed and incorporated into a coupled climate-thermodynamic sea ice (CCSI) model. The expanded CCSI model has been tested by comparing computed climate parameters with available observations and GCM modeling results. In general, the expanded model does a good job in simulating the large scale features of the atmospheric circulation and precipitation in both space and time. The expanded model has been used to examine the possibility that increased levels of CO_2 in the atmosphere may induce the growth of Northern Hemisphere ice sheets. Results of the study indicate that if summer ice albedo is high enough, and there is some mechanism for initially maintaining ice through the summer season, then it may be possible to have ice sheet growth under the conditions CO_2 induced warming, mainly the result of decreased summer ice melt in response to the higher land ice albedo, and not an increase in precipitation. The expanded model has also been used to examine the impact of Milankovitch solar radiation variations on the climate system, to study the mechanisms that produce glacial-interglacial cycles, especially with respect to the initiation of ice sheets. The results show the Milankovitch solar radiation variations affect the climate system most in the polar regions with the mean annual surface air temperature varying directly in response to changes in the annually averaged incoming solar radiation. However, the seasonal variations in the surface air temperatures are much more complex with large magnitude variations for brief times during the year. The study indicates that ice sheets may start to grow under the conditions of low insolation that occurred at 25, 70, and

Anatomic variation and orgasm: Could variations in anatomy explain differences in orgasmic success?

Science.gov (United States)

Emhardt, E; Siegel, J; Hoffman, L

2016-07-01

Though the public consciousness is typically focused on factors such as psychology, penis size, and the presence of the "G-spot," there are other anatomical and neuro-anatomic differences that could play an equal, or more important, role in the frequency and intensity of orgasms. Discovering these variations could direct further medical or procedural management to improve sexual satisfaction. The aim of this study is to review the available literature of anatomical sexual variation and to explain why this variation may predispose some patients toward a particular sexual experience. In this review, we explored the available literature on sexual anatomy and neuro-anatomy. We used PubMed and OVID Medline for search terms, including orgasm, penile size variation, clitoral variation, Grafenberg spot, and benefits of orgasm. First we review the basic anatomy and innervation of the reproductive organs. Then we describe several anatomical variations that likely play a superior role to popular known variation (penis size, presence of g-spot, etc). For males, the delicate play between the parasympathetic and sympathetic nervous systems is vital to achieve orgasm. For females, the autonomic component is more complex. The clitoris is the primary anatomical feature for female orgasm, including its migration toward the anterior vaginal wall. In conclusions, orgasms are complex phenomena involving psychological, physiological, and anatomic variation. While these variations predispose people to certain sexual function, future research should explore how to surgically or medically alter these. Clin. Anat. 29:665-672, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Tensor-optimized antisymmetrized molecular dynamics as a successive variational method in nuclear many-body system

Energy Technology Data Exchange (ETDEWEB)

Myo, Takayuki, E-mail: takayuki.myo@oit.ac.jp [General Education, Faculty of Engineering, Osaka Institute of Technology, Osaka 535-8585 (Japan); Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047 (Japan); Toki, Hiroshi [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047 (Japan); Ikeda, Kiyomi [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Horiuchi, Hisashi [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047 (Japan); Suhara, Tadahiro [Matsue College of Technology, Matsue 690-8518 (Japan)

2017-06-10

We study the tensor-optimized antisymmetrized molecular dynamics (TOAMD) as a successive variational method in many-body systems with strong interaction for nuclei. In TOAMD, the correlation functions for the tensor force and the short-range repulsion and their multiples are operated to the AMD state as the variational wave function. The total wave function is expressed as the sum of all the components and the variational space can be increased successively with the multiple correlation functions to achieve convergence. All the necessary matrix elements of many-body operators, consisting of the multiple correlation functions and the Hamiltonian, are expressed analytically using the Gaussian integral formula. In this paper we show the results of TOAMD with up to the double products of the correlation functions for the s-shell nuclei, {sup 3}H and {sup 4}He, using the nucleon–nucleon interaction AV8′. It is found that the energies and Hamiltonian components of two nuclei converge rapidly with respect to the multiple of correlation functions. This result indicates the efficiency of TOAMD for the power series expansion in terms of the tensor and short-range correlation functions.

The effect of tectonic evolution on lacustrine syn-rift sediment patters in Qikou Sag, Bohaiwan Basin, eastern China

Science.gov (United States)

Liao, Y.; Wang, H.; Xu, W.

2013-12-01

Normal fault arrays and associated relay ramps between two overlapping en-echelon normal faults are well known to control the deposition and distribution of sediments in alluvial, fluvial and deltaic systems in rift settings. The influence of transfer zones or relay ramps on sediment routes and dispersal patterns in subaqueous (deeper marine/lacustrine), however, is barely studied and hence less clear. Previous experimental studies indicate that subaqueous relay ramps may act as sediment transportation pathways if certain conditions are available. In this study, we integrate detailed structural and stratigraphic analysis with three-dimensional seismic data and limited well log data from the Qikou Sag to examine the tectonic evolution and the syn-rift sediment patterns response to fault growth and linkage in an active rift setting. Qikou Sag is located at the center of Huanghua Depression, Bohaiwan Basin of eastern China. Structurally, it is a typical continental rift basin characterized by a linked system of two NEE-SWW-striking half-grabens and one E-W-striking graben. Qikou sag is filled with Eocene-Oligocene syn-rift sediments and Miocene to Quaternary post-rift sediments. The Eocene-Oligocene rifting stage can be divided into early rifting period (43-36.5 Ma, the third member and second member of Shahejie Formation, Es3 and Es2), stable rifting period (36.5-29Ma, the first member of Shaehejie Formation, Es1) and fault-depressed diversionary period (29-24.6Ma, the Dongying Formation, Ed). This study focus on the early syn-rift, the third and second member of Shehejie Formation, which is mostly dark-grey mudstone interbedded with fine to coarse-grained sandstone deposited by large-scale turbidity currents in deep-lake. In particular, we use a combination of thickness variability and facies distributions, onlap patterns within a high-resolution sequence stratigraphic framework, integrated with structural geometry, fault activity and subsidence history analysis to

Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example

International Nuclear Information System (INIS)

Åberg, M.; Widén, J.; Henning, D.

2012-01-01

In the future, district heating companies in Sweden must adapt to energy efficiency measures in buildings and variable fuel and electricity prices. Swedish district heating demands are expected to decrease by 1–2% per year and electricity price variations seem to be more unpredictable in the future. A cost-optimisation model of a Swedish local district heating system is constructed using the optimisation modelling tool MODEST. A scenario for heat demand changes due to increased energy efficiency in buildings, combined with the addition of new buildings, is studied along with a sensitivity analysis for electricity price variations. Despite fears that heat demand reductions will decrease co-generation of clean electricity and cause increased global emissions, the results show that anticipated heat demand changes do not increase the studied system's primary energy use or global CO 2 emissions. The results further indicate that the heat production plants and the fuels used within the system have crucial importance for the environmental impact of district heat use. Results also show that low seasonal variations in electricity price levels with relatively low winter prices promote the use of electric heat pumps. High winter prices on the other hand promote co-generation of heat and electricity in CHP plants. -- Highlights: ► A MODEST optimisation model of the Uppsala district heating system is built. ► The impact of heat demand change on heat and electricity production is examined. ► An electricity price level sensitivity analysis for district heating is performed. ► Heat demand changes do not increase the primary energy use or global CO 2 emissions. ► Low winter prices promote use of electric heat pumps for district heating production.

Walking-adaptability assessments with the Interactive Walkway: Between-systems agreement and sensitivity to task and subject variations.

Science.gov (United States)

Geerse, Daphne J; Coolen, Bert H; Roerdink, Melvyn

2017-05-01

The ability to adapt walking to environmental circumstances is an important aspect of walking, yet difficult to assess. The Interactive Walkway was developed to assess walking adaptability by augmenting a multi-Kinect-v2 10-m walkway with gait-dependent visual context (stepping targets, obstacles) using real-time processed markerless full-body kinematics. In this study we determined Interactive Walkway's usability for walking-adaptability assessments in terms of between-systems agreement and sensitivity to task and subject variations. Under varying task constraints, 21 healthy subjects performed obstacle-avoidance, sudden-stops-and-starts and goal-directed-stepping tasks. Various continuous walking-adaptability outcome measures were concurrently determined with the Interactive Walkway and a gold-standard motion-registration system: available response time, obstacle-avoidance and sudden-stop margins, step length, stepping accuracy and walking speed. The same holds for dichotomous classifications of success and failure for obstacle-avoidance and sudden-stops tasks and performed short-stride versus long-stride obstacle-avoidance strategies. Continuous walking-adaptability outcome measures generally agreed well between systems (high intraclass correlation coefficients for absolute agreement, low biases and narrow limits of agreement) and were highly sensitive to task and subject variations. Success and failure ratings varied with available response times and obstacle types and agreed between systems for 85-96% of the trials while obstacle-avoidance strategies were always classified correctly. We conclude that Interactive Walkway walking-adaptability outcome measures are reliable and sensitive to task and subject variations, even in high-functioning subjects. We therefore deem Interactive Walkway walking-adaptability assessments usable for obtaining an objective and more task-specific examination of one's ability to walk, which may be feasible for both high

Testing a key assumption in animal communication: between-individual variation in female visual systems alters perception of male signals

Directory of Open Access Journals (Sweden)

Kelly L. Ronald

2017-12-01

Full Text Available Variation in male signal production has been extensively studied because of its relevance to animal communication and sexual selection. Although we now know much about the mechanisms that can lead to variation between males in the properties of their signals, there is still a general assumption that there is little variation in terms of how females process these male signals. Variation between females in signal processing may lead to variation between females in how they rank individual males, meaning that one single signal may not be universally attractive to all females. We tested this assumption in a group of female wild-caught brown-headed cowbirds (Molothrus ater, a species that uses a male visual signal (e.g. a wingspread display to make its mate-choice decisions. We found that females varied in two key parameters of their visual sensory systems related to chromatic and achromatic vision: cone densities (both total and proportions and cone oil droplet absorbance. Using visual chromatic and achromatic contrast modeling, we then found that this between-individual variation in visual physiology leads to significant between-individual differences in how females perceive chromatic and achromatic male signals. These differences may lead to variation in female preferences for male visual signals, which would provide a potential mechanism for explaining individual differences in mate-choice behavior.

Testing a key assumption in animal communication: between-individual variation in female visual systems alters perception of male signals.

Science.gov (United States)

Ronald, Kelly L; Ensminger, Amanda L; Shawkey, Matthew D; Lucas, Jeffrey R; Fernández-Juricic, Esteban

2017-12-15

Variation in male signal production has been extensively studied because of its relevance to animal communication and sexual selection. Although we now know much about the mechanisms that can lead to variation between males in the properties of their signals, there is still a general assumption that there is little variation in terms of how females process these male signals. Variation between females in signal processing may lead to variation between females in how they rank individual males, meaning that one single signal may not be universally attractive to all females. We tested this assumption in a group of female wild-caught brown-headed cowbirds ( Molothrus ater ), a species that uses a male visual signal (e.g. a wingspread display) to make its mate-choice decisions. We found that females varied in two key parameters of their visual sensory systems related to chromatic and achromatic vision: cone densities (both total and proportions) and cone oil droplet absorbance. Using visual chromatic and achromatic contrast modeling, we then found that this between-individual variation in visual physiology leads to significant between-individual differences in how females perceive chromatic and achromatic male signals. These differences may lead to variation in female preferences for male visual signals, which would provide a potential mechanism for explaining individual differences in mate-choice behavior. © 2017. Published by The Company of Biologists Ltd.

Accurate sizing of supercapacitors storage system considering its capacitance variation.

OpenAIRE

Trieste , Sony; Bourguet , Salvy; Olivier , Jean-Christophe; Loron , Luc; Le Claire , Jean-Claude

2011-01-01

International audience; This paper highlights the energy errors made for the design of supercapacitors used as a main energy source. First of all, the paper presents the two definitions of capacitance of a capacitance-voltage dependent material. The number of supercapacitors is important for the application purchasing cost. That is why the paper introduces an analytical model and an electrical model along with an identification method for the capacitance variation. This variation is presented...

Dopamine transporters govern diurnal variation in extracellular dopamine tone

OpenAIRE

Ferris, Mark J.; España, Rodrigo A.; Locke, Jason L.; Konstantopoulos, Joanne K.; Rose, Jamie H.; Chen, Rong; Jones, Sara R.

2014-01-01

The mechanism for diurnal (i.e., light/dark) oscillations in extracellular dopamine tone in mesolimbic and nigrostriatal systems is unknown. This is because, unlike other neurotransmitter systems, variation in dopamine tone does not correlate with variation in dopamine cell firing. The current research pinpoints the dopamine transporter as a critical governor of diurnal variation in both extracellular dopamine tone and the intracellular availability of releasable dopamine. These data describe...

Temporal correlation in the Goldberg variations

OpenAIRE

Chestopal, Victor

2010-01-01

An interpreter of the Goldberg Variations is almost completely deprived of such utterly important guidance as the composer's tempo markings, which are as rare in the Goldberg Variations as they are in the other works of Bach. The final goal of my study is to suggest a logical foundation, upon which an interpreter of the Goldberg Variations can make his/her choice of tempi. Upon the analysis of opus's structure, which reveals an impressive panorama of symmetries, I suggest a multilevel system ...

Geometrical treatment of non-potential interactions: the exterior variational calculus, dynamical systems, physical 1-forms and variational selfadjointness

International Nuclear Information System (INIS)

Trostel, R.

1982-01-01

A mathematical objective of this paper is to provide geometrical formulation of the integrability conditions for the existence of an action functional, that is, to provide a geometrical counterpart (similar to that by Abraham, Marsden, and Hughes) of the variational and functional approach to self-adjointness. This objective is achieved via the exterior variational calculus, an exterior differential calculus on the vector space of functions depending on time or space time, using from the outset extensively the concept of functional differentiation as its foundation. Variational self-adjointness equals the variational closure of the physical 1-form, the vanishing of a generalized curl-operation applied to the equations of motion. The convenience of this more formal approach is demonstrated, not only when deriving the conditions of variational self-adjointness for materials of differential type of arbitrary order (particles or fields), using roughly no more than Dirac's delta-distributions, but also when treating materials of a broader class (including causal and acausal constitutive functionals, materials of rate type, integral type, etc.). A physical objective of this paper is achieved by pointing out that, as physics is primarily concerned with the solutions of the evolution equations, i.e., with the set of the zero points of the physical 1-form, an equivalence relation among the physical 1-forms on the infinite dimensional vector space of functions is constructed by leaving the set of their zero points unchanged. Using this result, a direct Lagrangian universality is indicated and an almost one presented. Moreover, all physical 1-forms connected by invertible supermatrices (thus mixing the evolution law of different times or space-time) are equivalent. Choosing these supermatrices to be diagonal in time or space-time yields the indirect analytical representation factors

Amplitude variation in calibrated audiometer systems in Clinical Simulations

Directory of Open Access Journals (Sweden)

Christopher Barlow

2014-01-01

Full Text Available Manual pure tone audiometry is considered to be the gold standard for the assessment of hearing thresholds and has been in consistent use for a long period of time. An increased legislative requirement to monitor and screen workers, and an increasing amount of legislation relating to hearing loss is putting greater reliance on this as a tool. There are a number of questions regarding the degree of accuracy of pure tone audiometry when undertaken in field conditions, particularly relating to the difference in conditions between laboratory calibration and clinical or industrial screening use. This study analyzed the output sound pressure level of four different commercial audiometers, all using TDH39 headphones and each of which had recently undergone calibration at an appropriate laboratory. Levels were measured using a Bruël and Kjaer Head and Torso simulator, which accurately replicates the size and shape of a human head, including the ears. A clinical environment was simulated by a trained audiometrist replacing the headphones for each test. Tests were undertaken at three presentation levels, and at the frequencies of 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz and 6 kHz. The results showed a high level of test-retest variability, both between different audiometers and within the same audiometer. Maximum variation of sound pressure level at the ear for the same tone presentation was 21 decibels, with a particularly high level of variation at 6 kHz for all meters. An audiometer with attenuating cups exhibited significantly higher variation than ones using supral-aural headphones. Overall the variation exhibited suggests that there is a higher degree of potential error with screening pure tone audiometry than is commonly assumed and that results particularly at the 6 kHz frequency need to be assessed carefully alongside other methods such as speech audiometry.

''Use of perturbative methods to break down the variation of reactivity between two systems''

International Nuclear Information System (INIS)

Perruchot-Triboulet, S.; Sanchez, R.

1997-01-01

The modification of the isotopic composition, the temperature or even accounting for across section uncertainties in one part of a nuclear reactor core, affects the value of the effective multiplication factor. A new tool allows the analysis of the reactivity effect generated by the modification of the system. With the help of the direct and adjoint fluxes, a detailed balance of reactivity, between the compared systems, is done for each isotopic cross section. After the presentation of the direct and adjoint transport equations in the context of the multigroup code transport APOLLO2, this note describes the method, based on perturbation theory, for the analysis of the reactivity variation. An example application is also given. (author)

Multistep Hybrid Extragradient Method for Triple Hierarchical Variational Inequalities

Directory of Open Access Journals (Sweden)

Zhao-Rong Kong

2013-01-01

Full Text Available We consider a triple hierarchical variational inequality problem (THVIP, that is, a variational inequality problem defined over the set of solutions of another variational inequality problem which is defined over the intersection of the fixed point set of a strict pseudocontractive mapping and the solution set of the classical variational inequality problem. Moreover, we propose a multistep hybrid extragradient method to compute the approximate solutions of the THVIP and present the convergence analysis of the sequence generated by the proposed method. We also derive a solution method for solving a system of hierarchical variational inequalities (SHVI, that is, a system of variational inequalities defined over the intersection of the fixed point set of a strict pseudocontractive mapping and the solution set of the classical variational inequality problem. Under very mild conditions, it is proven that the sequence generated by the proposed method converges strongly to a unique solution of the SHVI.

Fractional action-like variational problems in holonomic, non-holonomic and semi-holonomic constrained and dissipative dynamical systems

Energy Technology Data Exchange (ETDEWEB)

EL-Nabulsi, Ahmad Rami [Department of Nuclear and Energy Engineering, Cheju National University, Ara-dong 1, Jeju 690-756 (Korea, Republic of)], E-mail: nabulsiahmadrami@yahoo.fr

2009-10-15

We communicate through this work the fractional calculus of variations and its corresponding Euler-Lagrange equations in 1D constrained holonomic, non-holonomic, and semi-holonomic dissipative dynamical system. The extension of the laws obtained to the 2D space state is done. Some interesting consequences are revealed.

A Prototype Regional GSI-based EnKF-Variational Hybrid Data Assimilation System for the Rapid Refresh Forecasting System: Dual-Resolution Implementation and Testing Results

Science.gov (United States)

Pan, Yujie; Xue, Ming; Zhu, Kefeng; Wang, Mingjun

2018-05-01

A dual-resolution (DR) version of a regional ensemble Kalman filter (EnKF)-3D ensemble variational (3DEnVar) coupled hybrid data assimilation system is implemented as a prototype for the operational Rapid Refresh forecasting system. The DR 3DEnVar system combines a high-resolution (HR) deterministic background forecast with lower-resolution (LR) EnKF ensemble perturbations used for flow-dependent background error covariance to produce a HR analysis. The computational cost is substantially reduced by running the ensemble forecasts and EnKF analyses at LR. The DR 3DEnVar system is tested with 3-h cycles over a 9-day period using a 40/˜13-km grid spacing combination. The HR forecasts from the DR hybrid analyses are compared with forecasts launched from HR Gridpoint Statistical Interpolation (GSI) 3D variational (3DVar) analyses, and single LR hybrid analyses interpolated to the HR grid. With the DR 3DEnVar system, a 90% weight for the ensemble covariance yields the lowest forecast errors and the DR hybrid system clearly outperforms the HR GSI 3DVar. Humidity and wind forecasts are also better than those launched from interpolated LR hybrid analyses, but the temperature forecasts are slightly worse. The humidity forecasts are improved most. For precipitation forecasts, the DR 3DEnVar always outperforms HR GSI 3DVar. It also outperforms the LR 3DEnVar, except for the initial forecast period and lower thresholds.

Soft sediment deformation structures in a lacustrine sedimentary succession induced by volcano-tectonic activities: An example from the Cretaceous Beolgeumri Formation, Wido Volcanics, Korea

Science.gov (United States)

Ko, Kyoungtae; Kim, Sung Won; Lee, Hong-Jin; Hwang, In Gul; Kim, Bok Chul; Kee, Won-Seo; Kim, Young-Seog; Gihm, Yong Sik

2017-08-01

The Cretaceous Beolgeumri Formation is composed of laminated mudstones intercalated with sandstones, chert, and a bed of lapilli tuff that were deposited in a lacustrine environment at the terminal part of a regional strike-slip fault systems on the southwestern Korean Peninsula. The Beolgeumri Formation contains various types of soft sediment deformation (SSD) structures that are characterized by a wide extent (features and deformation styles: 1) fold structures, 2) load structures, 3) water-escape structures, 4) rip-down structures, 5) boudin structures, and 6) synsedimentary fault structures. Field examination of SSD structures together with an analysis of the sedimentological records of the Beolgeumri Formation indicate that the SSD structures formed largely by liquefaction and/or fluidization triggered by ground shaking during earthquakes. To constrain the timing of the development of SSD structures in the Beolgeumri Formation, we conducted sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age dating of block sized lithic clasts bearing volcaniclastic deposits that conformably underlie (the Mangryeongbong Tuff) and overlie (the Ttandallae Tuff) the Beolgeumri Formation. The Mangryeongbong and Ttandallae Tuffs have ages of 86.63 ± 0.83 Ma and 87.24 ± 0.36 Ma, respectively, indicating that the Beolgeumri Formation was deposited during a short interval between major volcanic eruptions. The large lithic clasts of volcaniclastic deposits suggest that the Beolgeumri Formation was deposited adjacent to an active volcanic edifice(s). Syndepositional magmatic activities are suggested by the occurrence of a lapilli tuff bed in the Beolgeumri Formation and an igneous intrusion (intermediate sill) that is crosscut by a sand dike, as well as the similar age results of the underlying and overlying volcaniclastic deposits. Thus, we infer that the earthquakes that caused the development of SSD structures in the study area were closely related to syndepositional

Within-population variation in mating system and parental care patterns in the sanderling (Calidris alba) in northeast Greenland

NARCIS (Netherlands)

Reneerkens, Jeroen; van Veelen, Pieter; van der Velde, Marco; Luttikhuizen, Pieternella; Piersma, Theunis

Sandpipers and allies (Scolopacidae) show an astounding diversity in mating and parental care strategies. Comparative studies have tried to interpret this variation in terms of phylogenetic constraints and ecological shaping factors. In such analyses, mating and parental care systems are necessarily

Variational principles for locally variational forms

International Nuclear Information System (INIS)

Brajercik, J.; Krupka, D.

2005-01-01

We present the theory of higher order local variational principles in fibered manifolds, in which the fundamental global concept is a locally variational dynamical form. Any two Lepage forms, defining a local variational principle for this form, differ on intersection of their domains, by a variationally trivial form. In this sense, but in a different geometric setting, the local variational principles satisfy analogous properties as the variational functionals of the Chern-Simons type. The resulting theory of extremals and symmetries extends the first order theories of the Lagrange-Souriau form, presented by Grigore and Popp, and closed equivalents of the first order Euler-Lagrange forms of Hakova and Krupkova. Conceptually, our approach differs from Prieto, who uses the Poincare-Cartan forms, which do not have higher order global analogues

Accommodating variation: dialects, idiolects, and speech processing.

Science.gov (United States)

Kraljic, Tanya; Brennan, Susan E; Samuel, Arthur G

2008-04-01

Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production.

Enzyme-linked immunosorbent assay characterization of Basal variation and heritability of systemic microfibrillar-associated protein 4

DEFF Research Database (Denmark)

Sækmose, Susanne Gjørup; Schlosser, Anders; Holst, René

2013-01-01

Microfibrillar-associated protein 4 (MFAP4) is a systemic biomarker that is significantly elevated in samples from patients suffering from hepatic cirrhosis. The protein is generally localized to elastic fibers and other connective tissue fibers in the extracellular matrix (ECM), and variation...... in systemic MFAP4 (sMFAP4) has the potential to reflect diverse diseases with increased ECM turnover. Here, we aimed to validate an enzyme-linked immunosorbent assay (ELISA) for the measurement of sMFAP4 with an emphasis on the robustness of the assay. Moreover, we aimed to determine confounders influencing...

Exploring subdomain variation in biomedical language

Directory of Open Access Journals (Sweden)

Séaghdha Diarmuid Ó

2011-05-01

Full Text Available Abstract Background Applications of Natural Language Processing (NLP technology to biomedical texts have generated significant interest in recent years. In this paper we identify and investigate the phenomenon of linguistic subdomain variation within the biomedical domain, i.e., the extent to which different subject areas of biomedicine are characterised by different linguistic behaviour. While variation at a coarser domain level such as between newswire and biomedical text is well-studied and known to affect the portability of NLP systems, we are the first to conduct an extensive investigation into more fine-grained levels of variation. Results Using the large OpenPMC text corpus, which spans the many subdomains of biomedicine, we investigate variation across a number of lexical, syntactic, semantic and discourse-related dimensions. These dimensions are chosen for their relevance to the performance of NLP systems. We use clustering techniques to analyse commonalities and distinctions among the subdomains. Conclusions We find that while patterns of inter-subdomain variation differ somewhat from one feature set to another, robust clusters can be identified that correspond to intuitive distinctions such as that between clinical and laboratory subjects. In particular, subdomains relating to genetics and molecular biology, which are the most common sources of material for training and evaluating biomedical NLP tools, are not representative of all biomedical subdomains. We conclude that an awareness of subdomain variation is important when considering the practical use of language processing applications by biomedical researchers.

A variational approach to bifurcation points of a reaction-diffusion system with obstacles and neumann boundary conditions

Czech Academy of Sciences Publication Activity Database

Eisner, Jan; Kučera, Milan; Väth, Martin

2016-01-01

Roč. 61, č. 1 (2016), s. 1-25 ISSN 0862-7940 R&D Projects: GA ČR GA13-12580S Institutional support: RVO:67985904 ; RVO:67985840 Keywords : reaction-diffusion system * unlateral condition * variational inequality Subject RIV: EG - Zoology; BA - General Mathematics (MU-W) Impact factor: 0.618, year: 2016

Saline systems of the Great Plains of western Canada: an overview of the limnogeology and paleolimnology

Science.gov (United States)

Last, William M; Ginn, Fawn M

2005-01-01

spatial trends and regional variations controlled by groundwater input, climate, and geomorphology. Short-term temporal variations in the brine composition, which can have significant effects on the composition of the modern sediments, have also been well documented in several individual basins. From a sedimentological and mineralogical perspective, the wide range of water chemistries exhibited by the lakes leads to an unusually large diversity of modern sediment composition. Over 40 species of endogenic precipitates and authigenic minerals have been identified in the lacustrine sediments. The most common non-detrital components of the modern sediments include: calcium and calcium-magnesium carbonates (magnesian calcite, aragonite, dolomite), and sodium, magnesium, and sodium-magnesium sulfates (mirabilite, thenardite, bloedite, epsomite). Many of the basins whose brines have very high Mg/Ca ratios also have hydromagnesite, magnesite, and nesquehonite. Unlike salt lakes in many other areas of the world, halite, gypsum, and calcite are relatively rare endogenic precipitates in the Great Plains lakes. The detrital fraction of the lacustrine sediments is normally dominated by clay minerals, carbonate minerals, quartz, and feldspars. Sediment accumulation in these salt lakes is controlled and modified by a wide variety of physical, chemical, and biological processes. Although the details of these modern sedimentary processes can be exceedingly complex and difficult to discuss in isolation, in broad terms, the processes operating in the salt lakes of the Great Plains are ultimately controlled by three basic factors or conditions of the basin: (a) basin morphology; (b) basin hydrology; and (c) water salinity and composition. Combinations of these parameters interact to control nearly all aspects of modern sedimentation in these salt lakes and give rise to four 'end member' types of modern saline lacustrine settings in the Great Plains: (a) clastics-dominated playas; (b) salt

Isozyme variation in wild and cultivated pineapple

Science.gov (United States)

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Variational Monte Carlo Technique

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 8. Variational Monte Carlo Technique: Ground State Energies of Quantum Mechanical Systems. Sukanta Deb. General Article Volume 19 Issue 8 August 2014 pp 713-739 ...

Null alleles and sequence variations at primer binding sites of STR loci within multiplex typing systems.

Science.gov (United States)

Yao, Yining; Yang, Qinrui; Shao, Chengchen; Liu, Baonian; Zhou, Yuxiang; Xu, Hongmei; Zhou, Yueqin; Tang, Qiqun; Xie, Jianhui

2018-01-01

Rare variants are widely observed in human genome and sequence variations at primer binding sites might impair the process of PCR amplification resulting in dropouts of alleles, named as null alleles. In this study, 5 cases from routine paternity testing using PowerPlex ® 21 System for STR genotyping were considered to harbor null alleles at TH01, FGA, D5S818, D8S1179, and D16S539, respectively. The dropout of alleles was confirmed by using alternative commercial kits AGCU Expressmarker 22 PCR amplification kit and AmpFℓSTR ® . Identifiler ® Plus Kit, and sequencing results revealed a single base variation at the primer binding site of each STR locus. Results from the collection of previous reports show that null alleles at D5S818 were frequently observed in population detected by two PowerPlex ® typing systems and null alleles at D19S433 were mostly observed in Japanese population detected by two AmpFℓSTR™ typing systems. Furthermore, the most popular mutation type appeared the transition from C to T with G to A, which might have a potential relationship with DNA methylation. Altogether, these results can provide helpful information in forensic practice to the elimination of genotyping discrepancy and the development of primer sets. Copyright © 2017 Elsevier B.V. All rights reserved.

Reconstructing Holocene hematite and goethite variations in the Indus Canyon to trace changes in the Asian monsoon system

Science.gov (United States)

Koehler, Cornelia; Clift, Peter; Pressling, Nicola; Limmer, David; Giosan, Liviu; Tabrez, Ali

2010-05-01

In order to study Holocene Asian monsoon variations, we reconstructed changes in chemical weathering by examining sediments from the Indus Canyon. During the late Holocene, the Asian monsoon system had periods of high and low intensities that influenced the civilisations living in its realm. For example, the demise of the Harappan civilisation has been linked to a weakened monsoon system around 4 ka. The sediments in the Indus Canyon, which originate from the River Indus and its Himalayan tributaries, provide an ideal, natural environmental archive of the South Asian monsoon system. In order to investigate the alternation between arid and humid monsoonal climatic conditions, variations are traced using the magnetic minerals hematite and goethite, which form under distinct environmental conditions: goethite is stable under humid conditions, whereas hematite forms from the dehydration of goethite under arid conditions. The two minerals are characterised and quantified using environmental magnetic measurements, as well as diffuse reflectance spectrometry. Combining both approaches will enable us to reconstruct variations in chemical weathering over time. Furthermore, because this is governed by temperature and the availability of moisture, our weathering record will allow us to understand monsoon variability during the Holocene and test whether summer rain intensity has been decreasing in SW Asia since 8 ka. In addition, the multi-component analysis of colour reflectance spectra identifies different mineral components including hematite/goethite, clay mineral mixtures, calcite and organics. We will present our results from the multi-sensor core logger equipped with a Minolta spectrometer, measuring both magnetic susceptibility and the optical properties of the split sediment cores. Initial results indicate the presence of hematite and goethite in the sediment. There is an increasing hematite content up the cores, indicating an aridification trend during the Holocene

Long-term variations of fumarole temperatures on Vulcano Island (Italy

Directory of Open Access Journals (Sweden)

Iole Serena Diliberto

2011-06-01

Full Text Available Fumarole temperatures are the ultimate results of many processes that are encountered by deep fluids during their passage to the surface. Here, the time variations of high-temperature fumaroles acquired by continuous monitoring are presented, to show the effects of the forces that act on the system. Data acquired by continuous monitoring of fumaroles and the time relationships with the different parameters related to the activity of the volcanic system are discussed. From 1998 to 2010, the temperature and compositional changes of fumarolic gases were monitored at the same time as variations in the number of volcano-seismic events, which indicate frequent variations of energy release (heat and mass flow, and seismic strain release. Geochemical modeling applied to the volcanic system of Vulcano Island suggests that the overall expansion of magmatic gas through the fractured system is an almost iso-enthalpic process at depth, which shifts to an adiabatic process at shallow depth, where the rock permeability increases. Thus, the time variations of the fumarole temperatures reflect various physical variations of the system that can either occur at depth or close to the surface. The temperature monitoring performed in the fumarolic area of La Fossa Cone showed short-term effects related to rain events, and negligible effects related to other external agents (ambient temperature and atmospheric pressure variations. At the same time, the long-term monitoring highlighted some mean-term and long-term variations. These last are the main characters observed in the time-series, and they both appear to be related to endogenous forces that perturb the equilibrium of this complex geochemical system.

The GMAO Hybrid Ensemble-Variational Atmospheric Data Assimilation System: Version 2.0

Science.gov (United States)

Todling, Ricardo; El Akkraoui, Amal

2018-01-01

This document describes the implementation and usage of the Goddard Earth Observing System (GEOS) Hybrid Ensemble-Variational Atmospheric Data Assimilation System (Hybrid EVADAS). Its aim is to provide comprehensive guidance to users of GEOS ADAS interested in experimenting with its hybrid functionalities. The document is also aimed at providing a short summary of the state-of-science in this release of the hybrid system. As explained here, the ensemble data assimilation system (EnADAS) mechanism added to GEOS ADAS to enable hybrid data assimilation applications has been introduced to the pre-existing machinery of GEOS in the most non-intrusive possible way. Only very minor changes have been made to the original scripts controlling GEOS ADAS with the objective of facilitating its usage by both researchers and the GMAO's near-real-time Forward Processing applications. In a hybrid scenario two data assimilation systems run concurrently in a two-way feedback mode such that: the ensemble provides background ensemble perturbations required by the ADAS deterministic (typically high resolution) hybrid analysis; and the deterministic ADAS provides analysis information for recentering of the EnADAS analyses and information necessary to ensure that observation bias correction procedures are consistent between both the deterministic ADAS and the EnADAS. The nonintrusive approach to introducing hybrid capability to GEOS ADAS means, in particular, that previously existing features continue to be available. Thus, not only is this upgraded version of GEOS ADAS capable of supporting new applications such as Hybrid 3D-Var, 3D-EnVar, 4D-EnVar and Hybrid 4D-EnVar, it remains possible to use GEOS ADAS in its traditional 3D-Var mode which has been used in both MERRA and MERRA-2. Furthermore, as described in this document, GEOS ADAS also supports a configuration for exercising a purely ensemble-based assimilation strategy which can be fully decoupled from its variational component. We

Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

Science.gov (United States)

Ghosh, A.; Chakrabarti, Sandip K.

2016-09-01

Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of

Breeding system variation in 10 evening primroses (Oenothera sections Anogra and Kleinia; Onagraceae).

Science.gov (United States)

Theiss, Kathryn E; Holsinger, Kent E; Evans, Margaret E K

2010-06-01

We examined two accounts of the relationship between breeding system and life history variation in a clade of evening primroses (Oenothera, Onagraceae): (1) selection for reproductive assurance should generate an association between self-compatibility and monocarpy and (2) phylogenetic conservatism leads to retention of breeding system and life history traits among closely related taxa. • We performed over 4000 hand pollinations under greenhouse conditions to determine the compatibility of 10 Oenothera taxa (sections Anogra [17 taxa] and Kleinia [2 taxa)] for which breeding systems had not previously been reported. We used generalized linear mixed models to evaluate the influence of pollination treatment, parents, and population on fruiting success. • Among the taxa tested, six were self-incompatible, two were variable in compatibility, and two were self-compatible. We combined these data with published studies in Anogra and Kleinia and mapped breeding system and life history onto a published phylogeny. • We found no evidence for phylogenetic conservatism, but detected considerable evolutionary lability in both traits. Additionally, we found no evidence for a consistent relationship between breeding system and life history. Only eight of 19 taxa followed the predicted association between self-incompatibility and polycarpy vs. self-compatibility and monocarpy. Instead, many taxa have retained self-incompatibility, regardless of monocarpy or polycarpy.

Non-linear response of the Golo River system, Corsica, France, to Late Quaternary climatic and sea level variations

NARCIS (Netherlands)

Forzoni, A.; Storms, J.E.A.; Reimann, T.; Moreau, J.; Jouet, G.

2015-01-01

Disentangling the impact of climatic and sea level variations on fluvio-deltaic stratigraphy is still an outstanding question in sedimentary geology and geomorphology. We used the Golo River system, Corsica, France, as a natural laboratory to investigate the impact of Late Quaternary climate and sea

Abundance and δ13C values of fatty acids in lacustrine surface sediments: Relationships with in-lake methane concentrations

Science.gov (United States)

Stötter, Tabea; Bastviken, David; Bodelier, Paul L. E.; van Hardenbroek, Maarten; Rinta, Päivi; Schilder, Jos; Schubert, Carsten J.; Heiri, Oliver

2018-07-01

Proxy-indicators in lake sediments provide the only approach by which the dynamics of in-lake methane cycling can be examined on multi-decadal to centennial time scales. This information is necessary to constrain how lacustrine methane production, oxidation and emissions are expected to respond to global change drivers. Several of the available proxies for reconstructing methane cycle changes of lakes rely on interpreting past changes in the abundance or relevance of methane oxidizing bacteria (MOB), either directly (e.g. via analysis of bacterial lipids) or indirectly (e.g. via reconstructions of the past relevance of MOB in invertebrate diet). However, only limited information is available about the extent to which, at the ecosystem scale, variations in abundance and availability of MOB reflect past changes in in-lake methane concentrations. We present a study examining the abundances of fatty acids (FAs), particularly of 13C-depleted FAs known to be produced by MOB, relative to methane concentrations in 29 small European lakes. 39 surface sediment samples were obtained from these lakes and FA abundances were compared with methane concentrations measured at the lake surface, 10 cm above the sediments and 10 cm within the sediments. Three of the FAs in the surface sediment samples, C16:1ω7c, C16:1ω5c/t, and C18:1ω7c were characterized by lower δ13C values than the remaining FAs. We show that abundances of these FAs, relative to other short-chain FAs produced in lake ecosystems, are related with sedimentary MOB concentrations assessed by quantitative polymerase chain reaction (qPCR). We observed positive relationships between methane concentrations and relative abundances of C16:1ω7c, C16:1ω5c/t, and C18:1ω7c and the sum of these FAs. For the full dataset these relationships were relatively weak (Spearman's rank correlation (rs) of 0.34-0.43) and not significant if corrected for multiple testing. However, noticeably stronger and statistically significant

Morphology and biomass variations in root system of young tomato plants (Solanum sp.)

International Nuclear Information System (INIS)

Álvarez Gil, Marta A.; Fernández, Ana Fita; Ruiz Sánchez, María del C.; Bolarín Jiménez, María del C.

2016-01-01

The scarce exploitation of genotypic variability present in plant roots is an attractive breeding choice with regard to abiotic stresses and supports the objective of this work, which is to identify genotypic variation in root system traits of tomato genotypes (Solanum sp.). Thus, five tomato genotypes were studied: the commercial hybrid cultivar Jaguar (S. lycopersicum), Pera, Volgogradiskij and PE-47 entry (S. pennellii), which were collected in Peru, and the interspecific hybrid PeraxPE-47. Plants were grown in hydroponics for 26 days since germination; their roots were extracted and images were digitalized on scanner to evaluate total length, average diameter, the projected area and root length, following the categories per diameter of the whole root system through software Win Rhizo Pro 2003. The dry mass of roots and aerial parts was also recorded. Results indicated that genotypes differed in morphology, length according to diameter, root system spatial configuration and biomass, mainly with respect to the wild salinity resistant species PE-47. The interspecific hybrid PxPE-47 could be used as a rootstock to increase salt tolerance of susceptible cultivars. (author)

Within-individual variation in bullfrog vocalizations: implications for a vocally mediated social recognition system.

Science.gov (United States)

Bee, Mark A

2004-12-01

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.

Climate change alters the reproductive phenology and investment of a lacustrine fish, the three-spine stickleback.

Science.gov (United States)

Hovel, Rachel A; Carlson, Stephanie M; Quinn, Thomas P

2017-06-01

High-latitude lakes are particularly sensitive to the effects of global climate change, demonstrating earlier ice breakup, longer ice-free seasons, and increased water temperatures. Such physical changes have implications for diverse life-history traits in taxa across entire lake food webs. Here, we use a five-decade time series from an Alaskan lake to explore effects of climate change on growth and reproduction of a widely distributed lacustrine fish, the three-spine stickleback (Gasterosteus aculeatus). We used multivariate autoregressive state-space (MARSS) models to describe trends in the mean length for multiple size classes and to explore the influence of physical (date of ice breakup, surface water temperature) and biological (density of con- and heterospecifics) factors. As predicted, mean size of age 1 and older fish at the end of the growing season increased across years with earlier ice breakup and warmer temperatures. In contrast, mean size of age 0 fish decreased over time. Overall, lower fish density and warmer water temperatures were associated with larger size for all cohorts. Earlier ice breakup was associated with larger size for age 1 and older fish but, paradoxically, with smaller size of age 0 fish. To explore this latter result, we used mixing models on age 0 size distributions, which revealed an additional cohort in years with early ice breakup, lowering the mean size of age 0 fish. Moreover, early ice breakup was associated with earlier breeding, evidenced by earlier capture of age 0 fish. Our results suggest that early ice breakup altered both timing and frequency of breeding; three-spine stickleback spawned earlier and more often in response to earlier ice breakup date. While previous studies have shown the influence of changing conditions in northern lakes on breeding timing and growth, this is the first to document increased breeding frequency, highlighting another pathway by which climate change can alter the ecology of northern lakes

Novel approach to evaluate the dynamic variation of wind drift and evaporation losses under moving irrigation systems

Science.gov (United States)

Sayed-Hossein Sadeghi; Troy R. Peters; Mohammad Z. Amini; Sparkle L. Malone; Hank W. Loescher

2015-01-01

The increased need for water and food security requires the development of new approaches to save water through irrigation management strategies, particularly for center pivot irrigation. To do so entails monitoring of the dynamic variation in wind drift and evaporation losses (WDELs) of irrigation systems under different weather conditions and for relatively long time...

A New Look at the Eclipse Timing Variation Diagram Analysis of Selected 3-body W UMa Systems

Science.gov (United States)

Christopoulou, P.-E.; Papageorgiou, A.

2015-07-01

The light travel effect produced by the presence of tertiary components can reveal much about the origin and evolution of over-contact binaries. Monitoring of W UMa systems over the last decade and/or the use of publicly available photometric surveys (NSVS, ASAS, etc.) has uncovered or suggested the presence of many unseen companions, which calls for an in-depth investigation of the parameters derived from cyclic period variations in order to confirm or reject the assumption of hidden companion(s). Progress in the analysis of eclipse timing variations is summarized here both from the empirical and the theoretical points of view, and a more extensive investigation of the proposed orbital parameters of third bodies is proposed. The code we have developed for this, implemented in Python, is set up to handle heuristic scanning with parameter perturbation in parameter space, and to establish realistic uncertainties from the least squares fitting. A computational example is given for TZ Boo, a W UMa system with a spectroscopically detected third component. Future options to be implemented include MCMC and bootstrapping.

Variation of the solvation number of Eu(III) in mixed system of methanol and water

International Nuclear Information System (INIS)

Suganuma, H.; Arisaka, M.; Omori, T.; Satoh, I.; Choppin, G.R.

1999-01-01

The stability constants (β 1 ) of the monofluoride complex of Eu(III) have been determined in mixed solvents of methanol and water at a 0.10 M ionic strength using a solvent extraction technique. The values of ln β 1 increase as the mole fraction of methanol in the mixed solvent system increases. The variation in the stability constants can be correlated with both the large effect due to the solvation of F and the small effect due to both (1) the solvation of cations in connection with complexation and (2) the electrostatic attraction between Eu 3+ and F - . Based on the variation in the sum of (1) and (2) in water and the mixed solvent solutions, it was determined that the coordination number (CN) of Eu(III) varied from a mixture of CN = 9 and 8 to CN = 8 at about a 0.03 mole fraction of methanol in the mixed solvent. (orig.)

Tephra and cryptotephra in a 60,000-year-old lacustrine sequence from the Fucino Basin: new insights into the major explosive events in Italy

Science.gov (United States)

Di Roberto, Alessio; Smedile, Alessandra; Del Carlo, Paola; De Martini, Paolo Marco; Iorio, Marina; Petrelli, Maurizio; Pantosti, Daniela; Pinzi, Stefania; Todrani, Alessandro

2018-03-01

Two cores were sampled in the Fucino Basin (central Apennines, Italy), which represents an extensional intramountain basin filled by Pliocene to Quaternary continental alluvial and lacustrine deposits. The cores were investigated for tephra content and five visible tephras with thickness ranging from 1 to 8 cm were identified. Six additional cryptotephra were identified during the inspection of significant peaks of the magnetic susceptibility curve. Texture and mineralogy of five tephra and six cryptotephra layers were analyzed by means of scanning electron microscope coupled with energy-dispersive X-ray spectrometry system (SEM-EDS) and geochemical measurements were performed by an electron microprobe (EPMA) equipped with five wavelength-dispersive spectrometers (WDS) and using a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) system on single glass shards. The results allowed us to assign tephra and cryptotephra to ten known volcanic eruptions that occurred over the last ca. 60 ka in the Campanian Province (Phlegrean Fields and Ischia Island), the Alban Hills volcanic complex, and Lipari island. In particular, we recognized the deposits of the Monte Epomeo Green Tuff and the Piroclastiti di Catavola eruptions of Ischia, the pre-Campanian Ignimbrite Tlc, the Campanian Ignimbrite and the Neapolitan Yellow Tuff eruptions of the Phlegrean Fields, the Gabellotto-Fiume Bianco eruption of Lipari, and all the four explosive events belonging to the last cycle of volcanic activity of Albano maar (Albano 4-7). Deposits from five of these identified events (i.e., Piroclastiti di Catavola, Gabellotto-Fiume Bianco, Albano 5 and 6 eruptions, and Campanian Ignimbrite) were previously un-reported in the Fucino basin. These findings add new tephra layers to the list of possible tephrochronologic markers in the region and highlight that a comprehensive tephra record may be constructed when the study of cryptotephra layers is included. Moreover, results

VARIATIONAL PRINCIPLE FOR PLANETARY INTERIORS

International Nuclear Information System (INIS)

Zeng, Li; Jacobsen, Stein B.

2016-01-01

In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equations into one, which provides us some insight into the problem. From this principle, a universal mass–radius relation, an estimate of the error propagation from the equation of state to the mass–radius relation, and a form of the virial theorem applicable to planetary interiors are derived.

Petroleum systems and hydrocarbon accumulation models in the Santos Basin, SP, Brazil; Sistemas petroliferos e modelos de acumulacao de hidrocarbonetos na Bacia de Santos

Energy Technology Data Exchange (ETDEWEB)

Chang, Hung Kiang; Assine, Mario Luis; Correa, Fernando Santos; Tinen, Julio Setsuo [Universidade Estadual Paulista (UNESP), Rio Claro, SP (Brazil). Lab. de Estudos de Bacias]. E-mails: chang@rc.unesp.br; assine@rc.unesp.br; fscorrea@rc.unesp.br; jstinen@rc.unesp.br; Vidal, Alexandre Campane; Koike, Luzia [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro de Estudos de Petroleo]. E-mails: vidal@ige.unicamp.br; luzia@iqm.unicamp.br

2008-07-01

The Santos Basin was formed by rifting process during Mesozoic Afro-American separation. Sediment accumulation initiated with fluvial-lacustrine deposits, passing to evaporitic stage until reaching marginal basin stages. The analysis of hydrocarbon potential of Santos Basin identified two petroleum systems: Guaratiba-Guaruja and Itajai-Acu-Ilhabela. The Guaratiba Formation is less known in the Santos Basin because of small number of wells that have penetrated the rift section. By comparison with Campos Basin, hydrocarbons are of saline lacustrine origin deposited in Aptian age. Analogous to Campos Basin the major source rock is of saline-lacustrine origin, which has been confirmed from geochemical analyses of oil samples recovered from the various fields. These analyses also identified marine source rock contribution, indicating the Itajai-Acu source rock went through oil-window, particularly in structural lows generated by halokynesis. Models of hydrocarbon accumulation consider Guaratiba Formacao as the major source rock for shallow carbonate reservoirs of Guaruja Formacao and for late Albian to Miocene turbidites, as well as siliciclastic and carbonate reservoirs of the rift phase. Migration occurs along salt window and through carrier-beds. The seal rock is composed of shales and limestones intercalated with reservoir facies of the post-rift section and by thick evaporites overlying rift section, especially in the deeper water. In the shallow portion, shale inter-tongued with reservoir rocks is the main seal rock. The hydrocarbon generation and expulsion in the central-north portion of the basin is caused by overburden of a thick Senonian section. Traps can be structural (rollovers and turtle), stratigraphic (pinch-outs) and mixed origins (pinch-outs of turbidites against salt domes). (author)

Astronomically Forced Hydrology of the Late Cretaceous Sub-tropical Potosí Basin, Bolivia

Science.gov (United States)

Tasistro-Hart, A.; Maloof, A. C.; Schoene, B.; Eddy, M. P.

2017-12-01

Orbital forcings paced the ice ages of the Pleistocene, demonstrating that periodic variations in the latitudinal distribution of insolation amplified by ice-albedo feedbacks can guide global climate. How these forcings operate in the hot-houses that span most of the planet's history, however, is unknown. The lacustrine El Molino formation of the late Cretaceous-early Paleogene Potosí Basin in present-day Bolivia contains carbonate-mud parasequences that record fluctuating hydrological conditions from 73 to 63 Ma. This study presents the first cyclostratigraphic analysis using high-resolution drone-derived imagery and 3D elevation models, combined with conventional stratigraphic measurements and magnetic susceptibility data. The drone-derived data are integrated over the entire outcrop at two field areas using a novel application of stratigraphic potential field modeling that increases signal-to-noise ratios prior to spectral analysis. We demonstrate that these parasequences exhibit significant periodicities consistent with eccentricity (400 and 100 kyr), obliquity (50 kyr, 40 kyr, and 29 kyr), precession (17-23 kyr), and semi-precession (9-11 kyr). New U-Pb ID-TIMS zircon ages from intercalacted ash beds corroborate the interpreted sedimentation rates at two sites, indicating that the Potosí Basin contains evidence for hot-house astronomical forcing of sub-tropical lacustrine hydrology. Global climate simulations of late Cretaceous orbital end-member configurations demonstrate precessional-eccentricity and obliquity driven modulation of basin hydrology. In model simulations, the forcings drive long-term shifts in the location of the intertropical convergence zone, changing precipitation along the northern extent of the Potosí Basin's catchment area. This study is the first to demonstrate orbital forcing of a lacustrine system during the Maastrichtian and could ultimately contribute to a precise age for the Cretaceous-Paleogene boundary.

Variational principles for dissipative waves

Science.gov (United States)

Dodin, I. Y.; Ruiz, D. E.

2016-10-01

Variational methods are a powerful tool in plasma theory. However, their applications are typically restricted to conservative systems or require doubling of variables, which often contradicts the purpose of the variational approach altogether. We show that these restrictions can be relaxed for some classes of dynamical systems that are of practical interest in plasma physics, particularly including dissipative plasma waves. Applications will be discussed to calculating dispersion relations and modulational dynamics of individual plasma waves and wave ensembles. The work was supported by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

A passive heat tracer experiment to determine the seasonal variation in residence times in a managed aquifer recharge system with DTS

NARCIS (Netherlands)

des Tombe, B.F.; Bakker, M.; Schaars, F; van der Made, KJ; Calje, R; Borst, L.

2016-01-01

Targeted provisional session N°8.01 The seasonal variation in residence times is determined in a managed aquifer recharge system using a passive heat tracer test. The managed aquifer recharge system consists of a sequence of alternating elongated recharge basins and rows of recovery wells. The

Improved interobserver variation after training of doctors in the Neer system. A randomised trial

DEFF Research Database (Denmark)

Brorson, S; Bagger, J; Sylvest, A

2002-01-01

We investigated whether training doctors to classify proximal fractures of the humerus according to the Neer system could improve interobserver agreement. Fourteen doctors were randomised to two training sessions, or to no training, and asked to categorise 42 unselected pairs of plain radiographs...... of fractures of the proximal humerus according to the Neer system. The mean kappa difference between the training and control groups was 0.30 (95% CI 0.10 to 0.50, p = 0.006). In the training group the mean kappa value for interobserver variation improved from 0.27 (95% CI 0.24 to 0.31) to 0.62 (95% CI 0.......57 to 0.67). The improvement was particularly notable for specialists in whom kappa increased from 0.30 (95% CI 0.23 to 0.37) to 0.79 (95% CI 0.70 to 0.88). These results suggest that formal training in the Neer system is a prerequisite for its use in clinical practice and research....

Geothermal District Heating System City of Klamath Falls

Energy Technology Data Exchange (ETDEWEB)

Lienau, Paul J; Rafferty, Kevin

1991-12-01

The city of Klamath Falls became interested in the possibility of a establishing geothermal district heating system for downtown government buildings in January 1977. Since that time, the project has undergone some controversial and interesting developments that may be of educational value to other communities contemplating such a project. The purpose and content of this article is to identify the historical development of the project; including the design of the system, well owner objections to the project, aquifer testing, piping failure, and future expansion and marketing incentives. The shallow geothermal reservoir in Klamath falls extends for at least 6.8 miles in a northwest-southeast direction, as shown on Figure 1, with a width of about 2 miles. More than 550 thermal wells ranging in depth from about 10 to 2,000 ft, and obtaining or contacting water from 70 to 230oF, have been drilled into the reservoir. The system is not geologically homogeneous. Great variations in horizontal permeability and many vertical discontinuities exist because of stratigraphy and structure of the area. Basalt flows, eruptive centers, fluvial and lacustrine deposits, diatomite and pyroclastic materials alternate in the rock column. Normal faults with large throw (estimated up to 1,700 ft) are spaced less than 3,300 ft apart and appear to be the main avenue of vertical movement of hot fluids. In order to more effectively utilize this resource, the city of Klamath Falls decided in 1978 to apply for a federal grant (Program Opportunity Notice to cost share field experiment projects) to construct a geothermal district heating system that would deliver geothermal fluids to areas not located on the resource. In 1977, several Geo-Heat Center staff members visited Reykjavik, Iceland, to study the design of their geothermal district heating systems. This was in part the basis for the conceptual design and feasibility study (Lund, 1979) of a downtown commercial district. The main difference

FUSION DECISION FOR A BIMODAL BIOMETRIC VERIFICATION SYSTEM USING SUPPORT VECTOR MACHINE AND ITS VARIATIONS

Directory of Open Access Journals (Sweden)

A. Teoh

2017-12-01

Full Text Available This paw presents fusion detection technique comparisons based on support vector machine and its variations for a bimodal biometric verification system that makes use of face images and speech utterances. The system is essentially constructed by a face expert, a speech expert and a fusion decision module. Each individual expert has been optimized to operate in automatic mode and designed for security access application. Fusion decision schemes considered are linear, weighted Support Vector Machine (SVM and linear SVM with quadratic transformation. The conditions tested include the balanced and unbalanced conditions between the two experts in order to obtain the optimum fusion module from  these techniques best suited to the target application.

Hollow Nodules Gas Escape Sedimentary Structures in Lacustrine Deposits on Earth and Gale Crater

Science.gov (United States)

Bonaccorsi, R.; Willson, D.; Fairen, A. G.; Baker, L.; McKay, C.; Zent, A.; Mahaffy, P. R.

2015-12-01

Curiosity's Mastcam and MAHLI instruments in Gale Crater (GC) imaged mm-sized circular rimmed hollow nodules (HNs) (Figure 1A), pitting the Sheepbed mudstone of Yellowknife Bay Formation [1,2]. HNs are significantly smaller than the solid nodules within the outcrop, with an external mean diameter of 1.2 mm and an interior one of 0.7 mm [2] Several formation mechanisms of HNs have been discussed, such as: (1) Diagenetic dissolution of soluble mineral phases; or, (2) Gas bubbles released shortly after sediment deposition [1-3]. In an ephemeral pond in Ubehebe Crater (Death Valley, CA) we observed the formation of hollow nodule sedimentary structures produced by gas bubbles (Figure 1C) preserved in smectite-rich mud that are strikingly similar to those imaged in GC (Figure 1A). This finding supports the gas bubble hypothesis [2]. Ubehebe Crater (UC) surface sediment hollow nodules were sampled, imaged, and their internal diameter measured (200 hollow structures) showing similar shape, distribution, and composition to those imaged by Curiosity in GC. UC in-situ observations suggest the gas bubbles were generated within the slightly reducing ephemerally submerged mud. These intra-crater deposits remain otherwise extremely dry year round, i.e., Air_rH ~2-5%; ground H2O wt%: 1-2%; Summer air/ground T: 45-48ºC/67-70ºC [4-5]. Data from the Sample Analysis at Mars (SAM), CheMin, and ChemCam instruments onboard the rover revealed that HNs-bearing mudstone are rich in smectite clay e.g., ~18-20% [6,7] deposited in a neutral to mildly alkaline environment, capturing a period when the surface was potentially habitable [1]. The UC HNs-hosting deposits are also rich in smectite clays (~30%) and occur in an ephemeral shallow freshwater setting [4-5]. If present, surface hollow nodules are easy to find in dry clay-rich mud in lacustrine sediments, so they could represent a new indicator of ephemeral but habitable/inhabited environments on both Earth and early Mars. References: [1

Promise and Capability of NASA's Earth Observing System to Monitor Human-Induced Climate Variations

Science.gov (United States)

King, M. D.

2003-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. The Moderate Resolution Imaging Spectroradiometer (MODIS), developed as part of the Earth Observing System (EOS) and launched on Terra in December 1999 and Aqua in May 2002, is designed to meet the scientific needs for satellite remote sensing of clouds, aerosols, water vapor, and land and ocean surface properties. This sensor and multi-platform observing system is especially well suited to observing detailed interdisciplinary components of the Earth s surface and atmosphere in and around urban environments, including aerosol optical properties, cloud optical and microphysical properties of both liquid water and ice clouds, land surface reflectance, fire occurrence, and many other properties that influence the urban environment and are influenced by them. In this presentation I will summarize the current capabilities of MODIS and other EOS sensors currently in orbit to study human-induced climate variations.

Synchronized Pulsed dc - dc Converter as Maximum Power Position Tracker with Wide Load and Insolation Variation for Stand Alone PV System

International Nuclear Information System (INIS)

Hardik, P. Desai; Ranjan Maheshwari

2011-01-01

This paper investigates the interest focused on employing parallel connected dc-dc converter with high tracking effectiveness under wide variation in environmental conditions (Insolation) and wide load variation. dc-dc converter is an essential part of the stand alone PV system. Paper also presents an approach on how duty cycle for maximum power position (MPP) is adjusted by taking care of varying load conditions and without iterative steps. Synchronized PWM pulses are employed for the converter. High tracking efficiency is achieved with continuous input and inductor current. In this approach, the converter can he utilized in buck as well in boost mode. The PV system simulation was verified and experimental results were in agreement to the presented scheme. (authors)

Spatiotemporal climatic, hydrological, and environmental variations based on records of annually laminated lake sediments from northern Poland

Science.gov (United States)

Tylmann, W.; Blanke, L.; Kinder, M.; Loewe, T.; Mayr, C.; Ohlendorf, C.; Zolitschka, B.

2009-12-01

In northern Poland there is the unique opportunity to compare varved lake sediment records with distinct climatic trends along a 700 km long W-E transect. Annually laminated Holocene sediment sequences from Lake Lubinskie, Lake Suminko, Lake Lazduny, and Lake Szurpily were cored for high-resolution multiproxy climate and environmental reconstruction in the framework of the Polish-German project “Northern Polish Lake Research” (NORPOLAR). First results from a 139 cm long gravity core of Lake Lazduny (53°51.4’N, 21°57.3’E) document deposition of an organic (mean organic matter: 13.9%; mean biogenic opal: 9.8%) and highly carbonaceous gyttja (mean calcite content: 61.6%). The finely laminated sediment consists of biochemical varves. Pale spring/summer layers composed of autochthonous carbonates alternate with dark fall/winter layers made of organic and minerogenic detritus. The established chronology for the last 1500 calendar-years is based on thin section analysis supported by independent radiometric dating (C-14, Pb-210). Sedimentological, geochemical and stable isotope analyses were carried out with a decadal temporal resolution. Additionally, non-destructive and high-resolution XRF scanning data reveal a rhythmic variation in the Ca content that reflects seasonal calcite deposition. Redox-sensitive elements like Fe, Mn and S are interpreted to be the response to mean winter temperatures: colder winter temperatures → extended lake ice cover → intensification of meromixis → increased Fe/Mn ratio. In turn, these parameters can be linked to NAO (North Atlantic Oscillation) variability, because a negative NAO is related to colder and drier conditions in northeastern Europe. Climate variability is also mirrored by the δ13C record of the endogenic calcite fraction. In mid-latitude lakes calcite precipitation is dominated by productivity-controlled consumption of the dissolved inorganic carbon (DIC) pool. Thus the δ13C record potentially provides a

Characteristics of iron corrosion scales and water quality variations in drinking water distribution systems of different pipe materials.

Science.gov (United States)

Li, Manjie; Liu, Zhaowei; Chen, Yongcan; Hai, Yang

2016-12-01

Interaction between old, corroded iron pipe surfaces and bulk water is crucial to the water quality protection in drinking water distribution systems (WDS). Iron released from corrosion products will deteriorate water quality and lead to red water. This study attempted to understand the effects of pipe materials on corrosion scale characteristics and water quality variations in WDS. A more than 20-year-old hybrid pipe section assembled of unlined cast iron pipe (UCIP) and galvanized iron pipe (GIP) was selected to investigate physico-chemical characteristics of corrosion scales and their effects on water quality variations. Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Inductively Coupled Plasma (ICP) and X-ray Diffraction (XRD) were used to analyze micromorphology and chemical composition of corrosion scales. In bench testing, water quality parameters, such as pH, dissolved oxygen (DO), oxidation reduction potential (ORP), alkalinity, conductivity, turbidity, color, Fe 2+ , Fe 3+ and Zn 2+ , were determined. Scale analysis and bench-scale testing results demonstrated a significant effect of pipe materials on scale characteristics and thereby water quality variations in WDS. Characteristics of corrosion scales sampled from different pipe segments show obvious differences, both in physical and chemical aspects. Corrosion scales were found highly amorphous. Thanks to the protection of zinc coatings, GIP system was identified as the best water quality stability, in spite of high zinc release potential. It is deduced that the complicated composition of corrosion scales and structural break by the weld result in the diminished water quality stability in HP system. Measurement results showed that iron is released mainly in ferric particulate form. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sulfosys (Sulfolobus Systems Biology): towards a silicon cell model for the central carbohydrate metabolism of the archaeon Sulfolobus solfataricus under temperature variation.

NARCIS (Netherlands)

Albers, S.V.; Birkeland, N.K.; Driessen, A.J.; Gertig, S.; Haferkamp, P.; Klenk, H.P.; Kouril, T.; Manica, A.; Pham, T.K.; Ruoff, P.; Schleper, C.; Schomburg, D.; Sharkey, K.J.; Siebers, B.; Sierocinski, P.; Steuer, R.; van der Oost, J.; Westerhoff, H.V.; Wieloch, P.; Wright, P.C.; Zaparty, M.

2009-01-01

SulfoSYS (Sulfolobus Systems Biology) focuses on the study of the CCM (central carbohydrate metabolism) of Sulfolobus solfataricus and its regulation under temperature variation at the systems level. In Archaea, carbohydrates are metabolized by modifications of the classical pathways known from

Intraspecific variation in social organization by genetic variation, developmental plasticity, social flexibility or entirely extrinsic factors.

Science.gov (United States)

Schradin, Carsten

2013-05-19

Previously, it was widely believed that each species has a specific social organization, but we know now that many species show intraspecific variation in their social organization. Four different processes can lead to intraspecific variation in social organization: (i) genetic variation between individuals owing to local adaptation (between populations) or evolutionarily stable strategies within populations; (ii) developmental plasticity evolved in long-term (more than one generation) unpredictable and short-term (one generation) predictable environments, which is mediated by organizational physiological effects during early ontogeny; (iii) social flexibility evolved in highly unpredictable environments, which is mediated by activational physiological effects in adults; (iv) entirely extrinsic factors such as the death of a dominant breeder. Variation in social behaviour occurs between individuals in the case of genetic variation and developmental plasticity, but within individuals in the case of social flexibility. It is important to study intraspecific variation in social organization to understand the social systems of species because it reveals the mechanisms by which species can adapt to changing environments, offers a useful tool to study the ultimate and proximate causes of sociality, and is an interesting phenomenon by itself that needs scientific explanation.

Applications of Pharmacogenetics in Revealing Variations in ...

African Journals Online (AJOL)

This review article presents the latest findings of genetic variations in pharmacological targets related to disorders of major systems such as central nervous system, cardiovascular system, and the respiratory system especially in relation to asthma and the HLA antigen genotype in hypersensitivity reactions. East and Central ...

Modelling the Probability Density Function of IPTV Traffic Packet Delay Variation

Directory of Open Access Journals (Sweden)

Michal Halas

2012-01-01

Full Text Available This article deals with modelling the Probability density function of IPTV traffic packet delay variation. The use of this modelling is in an efficient de-jitter buffer estimation. When an IP packet travels across a network, it experiences delay and its variation. This variation is caused by routing, queueing systems and other influences like the processing delay of the network nodes. When we try to separate these at least three types of delay variation, we need a way to measure these types separately. This work is aimed to the delay variation caused by queueing systems which has the main implications to the form of the Probability density function.

Variational transition state theory

International Nuclear Information System (INIS)

Truhlar, D.G.

1986-01-01

This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. They have developed and implemented several practical versions of variational transition state theory (VTST), namely canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (μVT). They have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small-curvature semiclassical adiabatic (SCSA), large-curvature version-3 (LC3), and least-action (LA) approximations. They have applied the methods to thermal rate constants, using transmission coefficients based on ground-state tunneling, and they have also presented and applied adiabatic and diabatic extensions to calculated rate constants for vibrationally excited reactants. Their general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of their work is the determination or modeling, semi-empirically and/or from electronic structure calculations, of potential energy surfaces

Structural system identification based on variational mode decomposition

Science.gov (United States)

Bagheri, Abdollah; Ozbulut, Osman E.; Harris, Devin K.

2018-03-01

In this paper, a new structural identification method is proposed to identify the modal properties of engineering structures based on dynamic response decomposition using the variational mode decomposition (VMD). The VMD approach is a decomposition algorithm that has been developed as a means to overcome some of the drawbacks and limitations of the empirical mode decomposition method. The VMD-based modal identification algorithm decomposes the acceleration signal into a series of distinct modal responses and their respective center frequencies, such that when combined their cumulative modal responses reproduce the original acceleration response. The decaying amplitude of the extracted modal responses is then used to identify the modal damping ratios using a linear fitting function on modal response data. Finally, after extracting modal responses from available sensors, the mode shape vector for each of the decomposed modes in the system is identified from all obtained modal response data. To demonstrate the efficiency of the algorithm, a series of numerical, laboratory, and field case studies were evaluated. The laboratory case study utilized the vibration response of a three-story shear frame, whereas the field study leveraged the ambient vibration response of a pedestrian bridge to characterize the modal properties of the structure. The modal properties of the shear frame were computed using analytical approach for a comparison with the experimental modal frequencies. Results from these case studies demonstrated that the proposed method is efficient and accurate in identifying modal data of the structures.

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

Science.gov (United States)

Lenz, Josefine; Jones, Benjamin M.; Wetterich, Sebastian; Tjallingii, Rik; Fritz, Michael; Arp, Christopher D.; Rudaya, Natalia; Grosse, Guido

2016-01-01

Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation, and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological, and geochemical proxies. Radiocarbon and 210Pb/137Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of ~1400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the “alder high” that occurred in the region ~4000 cal yr BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were, therefore, archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China

Directory of Open Access Journals (Sweden)

Yong-Qiang Yang

2016-11-01

Full Text Available Abstract The genesis of the fine crystalline dolomites that exhibit good to excellent reservoir properties in the upper fourth member of the Eocene Shahejie Formation (Es 4 s around the Sikou Sag, Bohai Bay Basin, is uncertain. This paper investigates the formation mechanisms of this fine crystalline dolomite using XRD, SEM, thin section analysis and geochemical data. The stratigraphy of the Sikou lacustrine carbonate is dominated by the repetition of metre-scale, high-frequency deposition cycles, and the amount of dolomite within a cycle increases upward from the cycle bottom. These dolomite crystals are 2–30 μm in length, subhedral to anhedral in shape and typically replace both grains and matrix. They also occur as rim cement and have thin lamellae within ooid cortices. Textural relations indicate that the dolomite predates equant sparry calcite cement and coarse calcite cement. The Sr concentrations of dolomites range from 900 to 1200 ppm. Dolomite δ18O values (−11.3 to −8.2 ‰ PDB are depleted relative to calcite mudstone (−8.3 to −5.4 ‰ PDB that precipitated from lake water, while δ13C values (0.06–1.74 ‰ PDB are within the normal range of calcite mudstone values (−2.13 to 1.99 ‰ PDB. High 87Sr/86Sr values (0.710210–0.710844 indicate that amounts of Ca2+ and Mg2+ have been derived from the chemical weathering of Palaeozoic carbonate bedrocks. The high strontium concentration indicates that hypersaline conditions were maintained during the formation of the dolomites and that the dolomites were formed by the replacement of precursor calcite or by direct precipitation.

Task demands and individual variation in referring expressions

NARCIS (Netherlands)

Baltaretu, Adriana-Alexandra; Castro Ferreira, Thiago

Aiming to improve the human-likeness of natural language generation systems, this study investigates different sources of variation that might influence the production of referring expressions (REs), namely the effect of task demands and inter- intra- individual variation. We collected REs using a

Natural variations in the geomagnetically trapped electron population

Science.gov (United States)

Vampola, A. L.

1972-01-01

Temporal variations in the trapped natural electron flux intensities and energy spectra are discussed and demonstrated using recent satellite data. These data are intended to acquaint the space systems engineer with the types of natural variations that may be encountered during a mission and to augment the models of the electron environment currently being used in space system design and orbit selection. An understanding of the temporal variations which may be encountered should prove helpful. Some of the variations demonstrated here which are not widely known include: (1) addition of very energetic electrons to the outer zone during moderate magnetic storms: (2) addition of energetic electrons to the inner zone during major magnetic storms; (3) inversions in the outer zone electron energy spectrum during the decay phase of a storm injection event and (4) occasional formation of multiple maxima in the flux vs altitude profile of moderately energetic electrons.

Measuring Chemotherapy Appointment Duration and Variation Using Real-Time Location Systems.

Science.gov (United States)

Barysauskas, Constance M; Hudgins, Gina; Gill, Katie Kupferberg; Camuso, Kristen M; Bagley, Janet; Rozanski, Sheila; Kadish, Sarah

Clinical schedules drive resource utilization, cost, and patient wait time. Accurate appointment duration allocation ensures appropriate staffing ratios to daily caseloads and maximizes scarce resources. Dana-Farber Cancer Institute (DFCI) infusion appointment duration is adjusted by regimen using a consensus method of experts including pharmacists, nurses, and administrators. Using real-time location system (RTLS), we examined the accuracy of observed appointment duration compared with the scheduled duration. Appointment duration was calculated using RTLS at DFCI between August 1, 2013, and September 30, 2013. Duration was defined as the total time a patient occupied an infusion chair. The top 10 administered infusion regimens were investigated (n = 805). Median observed appointment durations were statistically different than the scheduled durations. Appointment durations were shorter than scheduled 98% (C), 95% (I), and 75% (F) of the time and longer than scheduled 77% (A) and 76% (G) of the time. Fifty-six percent of the longer than scheduled (A) appointments were at least 30 minute longer. RTLS provides reliable and unbiased data to improve schedule accuracy. Replacing consensus with system-based data may improve clinic flow, relieve staff stress, and increase patient satisfaction. Further investigation is warranted to elucidate factors that impact variation in appointment duration.

Enzyme-linked immunosorbent assay characterization of basal variation and heritability of systemic microfibrillar-associated protein 4.

Directory of Open Access Journals (Sweden)

Susanne Gjørup Sækmose

Full Text Available BACKGROUND: Microfibrillar-associated protein 4 (MFAP4 is a systemic biomarker that is significantly elevated in samples from patients suffering from hepatic cirrhosis. The protein is generally localized to elastic fibers and other connective tissue fibers in the extracellular matrix (ECM, and variation in systemic MFAP4 (sMFAP4 has the potential to reflect diverse diseases with increased ECM turnover. Here, we aimed to validate an enzyme-linked immunosorbent assay (ELISA for the measurement of sMFAP4 with an emphasis on the robustness of the assay. Moreover, we aimed to determine confounders influencing the basal sMFAP4 variability and the genetic contribution to the basal variation. METHODS: The sandwich ELISA was based on two monoclonal anti-MFAP4 antibodies and was optimized and calibrated with a standard of recombinant MFAP4. The importance of pre-analytical sample handling was evaluated regarding sample tube type, time, and temperature conditions. The mean value structure and variance structure was determined in a twin cohort including 1,417 Danish twins (age 18-67 years by mixed-effect linear regression modeling. RESULTS: The practical working range of the sandwich ELISA was estimated to be 4-75 U/ml. The maximum intra- and inter-assay variation was estimated to be 8.7% and 6.6%, respectively. Sample handling and processing appeared to influence MFAP4 measurements only marginally. The average concentration of sMFAP4 in the serum was 18.9 ± 8.4 (SD U/ml in the twin cohort (95% CI: 18.5-19.4, median sMFAP4 17.3 U/ml. The mean structure model was demonstrated to include waist-hip ratio, age, and cigarette smoking status in interactions with gender. A relatively low heritability of h(2 = 0.24 was found after applying a model including additive genetic factors and shared and non-shared environmental factors. CONCLUSIONS: The described ELISA provides robust measures of the liver fibrosis marker sMFAP4. The low heritability and the relatively

Analysis on sequence stratigraphy and depositional systems of Mangbang formation, upper tertiary in Longchuanjiang basin

International Nuclear Information System (INIS)

Sun Zexuan; Yao Yifeng; Chen Yong; Li Guoxin

2004-01-01

Longchuanjiang basin is a small Cenozoic intramontane down-faulted basin. This paper, combining the Pliocene structure, the volcanic activities and the sedimentation of the basin, analyses the sequence stratigraphy and the depositional systems of Mangbang formation (the cover of the basin). Based on the analysis of depositional systems of Mangbang formation, the depositional pattern of Pliocene in Longchuanjiang basin is set up. It is suggested that because of the fast accumulation in early down-faulted zone during Pliocene time, the alluvial fan depositional system was dominated at that time. During the middle-late period, the alluvial fan entered the lake forming a combination of fan-fandelta-lacustrine depositional systems. Authors propose a view point that the formation of Mangbang formation sequence was constrained by multistage tectonic movement, and three structural sequences were established, and system tracts were divided. (authors)

The effect of seasonal variation on the performances of grid connected photovoltaic system in southern of Algeria

Science.gov (United States)

Zaghba, L.; Khennane, M.; Terki, N.; Borni, A.; Bouchakour, A.; Fezzani, A.; Mahamed, I. Hadj; Oudjana, S. H.

2017-02-01

This paper presents modeling, simulation, and analysis evaluation of the grid-connected PV generation system performance under MATLAB/Simulink. The objective is to study the effect of seasonal variation on the performances of grid connected photovoltaic system in southern of Algeria. This system works with a power converter. This converter allows the connection to the network and extracts maximum power from photovoltaic panels with the MPPT algorithm based on robust neuro-fuzzy sliding approach. The photovoltaic energy produced by the PV generator will be completely injected on the network. Simulation results show that the system controlled by the neuro-fuzzy sliding adapts to changing external disturbances and show their effectiveness not only for continued maximum power point but also for response time and stability.

Variational approach to nuclear fluid dynamics

International Nuclear Information System (INIS)

Da Providencia, J.P.; Holzwarth, G.

1983-01-01

A variational derivation of a fluid-dynamical formalism for finite Fermi systems is presented which is based on a single determinant as variational function and does not exclude the possibility of transverse flow. Therefore the explicit specification of the time-odd part has to go beyond the local chi-approximation, while the time-even part is taken in the generalized scaling form. The necessary boundary conditions are derived from the variation of the lagrangian. The results confirm previous simplified approaches to a remarkable degree for quadrupole modes; for other multipolarities the deviations are much less than might be expected according to a sizeable change in the transverse sound speed. (orig.)

Allozyme variation in spineless Pejibaye (Bactris gasipaes Kunth)

Science.gov (United States)

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Practice Variation in Public Sector Internal Auditing

DEFF Research Database (Denmark)

Arena, Marika; Jeppesen, Kim Klarskov

2016-01-01

This article aims to analyze the rise of practice variations in public sector internal auditing (IA), giving special attention to the role of agents’ embeddedness in multiple institutional arrangements. IA's trends of development and the characteristics of the public sector context, in fact, make...... types of IA developed in three case settings, shaped by the agents’ embeddedness in different institutional fields. This article provides a more comprehensive approach to the study of IA adoption and development in public sector organizations than previous literature, and it highlights the relevance...... of the interplay between actors’ contemporary embeddedness in professional systems and the focal social system as a relevant source of practice variation. In this respect, the case of IA can contribute to previous studies of practice variation in the field of management accounting, shedding some light on the types...

H(infinity)/H(2)/Kalman filtering of linear dynamical systems via variational techniques with applications to target tracking

Science.gov (United States)

Rawicz, Paul Lawrence

In this thesis, the similarities between the structure of the H infinity, H2, and Kalman filters are examined. The filters used in this examination have been derived through duality to the full information controller. In addition, a direct variation of parameters derivation of the Hinfinity filter is presented for both continuous and discrete time (staler case). Direct and controller dual derivations using differential games exist in the literature and also employ variational techniques. Using a variational, rather than a differential games, viewpoint has resulted in a simple relationship between the Riccati equations that arise from the derivation and the results of the Bounded Real Lemma. This same relation has previously been found in the literature and used to relate the Riccati inequality for linear systems to the Hamilton Jacobi inequality for nonlinear systems when implementing the Hinfinity controller. The Hinfinity, H2, and Kalman filters are applied to the two-state target tracking problem. In continuous time, closed form analytic expressions for the trackers and their performance are determined. To evaluate the trackers using a neutral, realistic, criterion, the probability of target escape is developed. That is, the probability that the target position error will be such that the target is outside the radar beam width resulting in a loss of measurement. In discrete time, a numerical example, using the probability of target escape, is presented to illustrate the differences in tracker performance.

Variational methods in molecular modeling

CERN Document Server

2017-01-01

This book presents tutorial overviews for many applications of variational methods to molecular modeling. Topics discussed include the Gibbs-Bogoliubov-Feynman variational principle, square-gradient models, classical density functional theories, self-consistent-field theories, phase-field methods, Ginzburg-Landau and Helfrich-type phenomenological models, dynamical density functional theory, and variational Monte Carlo methods. Illustrative examples are given to facilitate understanding of the basic concepts and quantitative prediction of the properties and rich behavior of diverse many-body systems ranging from inhomogeneous fluids, electrolytes and ionic liquids in micropores, colloidal dispersions, liquid crystals, polymer blends, lipid membranes, microemulsions, magnetic materials and high-temperature superconductors. All chapters are written by leading experts in the field and illustrated with tutorial examples for their practical applications to specific subjects. With emphasis placed on physical unders...

A variational approach to niche construction.

Science.gov (United States)

Constant, Axel; Ramstead, Maxwell J D; Veissière, Samuel P L; Campbell, John O; Friston, Karl J

2018-04-01

In evolutionary biology, niche construction is sometimes described as a genuine evolutionary process whereby organisms, through their activities and regulatory mechanisms, modify their environment such as to steer their own evolutionary trajectory, and that of other species. There is ongoing debate, however, on the extent to which niche construction ought to be considered a bona fide evolutionary force, on a par with natural selection. Recent formulations of the variational free-energy principle as applied to the life sciences describe the properties of living systems, and their selection in evolution, in terms of variational inference. We argue that niche construction can be described using a variational approach. We propose new arguments to support the niche construction perspective, and to extend the variational approach to niche construction to current perspectives in various scientific fields. © 2018 The Authors.

Variational lower bound on the scattering length

International Nuclear Information System (INIS)

Rosenberg, L.; Spruch, L.

1975-01-01

The scattering length A characterizes the zero-energy scattering of one system by another. It was shown some time ago that a variational upper bound on A could be obtained using methods, of the Rayleigh-Ritz type, which are commonly employed to obtain upper bounds on energy eigenvalues. Here we formulate a method for obtaining a variational lower bound on A. Once again the essential idea is to express the scattering length as a variational estimate plus an error term and then to reduce the problem of bounding the error term to one involving bounds on energy eigenvalues. In particular, the variational lower bound on A is rigorously established provided a certin modified Hamiltonian can be shown to have no discrete states lying below the level of the continuum threshold. It is unfortunately true that necessary conditions for the existence of bound states are not available for multiparticle systems in general. However, in the case of positron-atom scattering the adiabatic approximation can be introduced as an (essentially) solvable comparison problem to rigorously establish the nonexistence of bound states of the modified Hamiltonian. It has recently been shown how the validity of the variational upper bound on A can be maintained when the target ground-state wave function is imprecisely known. Similar methods can be used to maintain the variational lower bound on A. Since the bound is variational, the error in the calculated scattering length will be of second order in the error in the wave function. The use of the adiabatic approximation in the present context places no limitation in principle on the accuracy achievable

[Sediment-water flux and processes of nutrients and gaseous nitrogen release in a China River Reservoir].

Science.gov (United States)

Chen, Zhu-hong; Chen, Neng-wang; Wu, Yin-qi; Mo, Qiong-li; Zhou, Xing-peng; Lu, Ting; Tian, Yun

2014-09-01

The key processes and fluxes of nutrients (N and P) and gaseous N (N2 and N2O) across the sediment-water interface in a river reservoir (Xipi) of the Jiulong River watershed in southeast China were studied. Intact core sediment incubation of nutrients exchange, in-situ observation and lab incubation of excess dissolved N2 and N2O (products of nitrification, denitrification and Anammox), and determination of physiochemical and microbe parameters were carried out in 2013 for three representative sites along the lacustrine zone of the reservoir. Results showed that ammonium and phosphate were generally released from sediment to overlying water [with averaged fluxes of N (479.8 ± 675.4) mg. (m2. d)-1 and P (4. 56 ± 0.54) mg. (m2 d) -1] , while nitrate and nitrite diffused into the sediment. Flood events in the wet season could introduce a large amount of particulate organic matter that would be trapped by the dam reservoir, resulting in the high release fluxes of ammonium and phosphate observed in the following low-flow season. No clear spatial variation of sediment nutrient release was found in the lacustrine zone of the reservoir. Gaseous N release was dominated by excess dissolved N2 (98% of total), and the N2 flux from sediment was (15.8 ± 12. 5) mg (m2. d) -1. There was a longitudinal and vertical variation of excess dissolved N2, reflecting the combined results of denitrification and Anammox occurring in anoxic sediment and fluvial transport. Nitrification mainly occurred in the lower lacustrine zone, and the enrichment of N2O was likely regulated by the ratio of ammonium to DIN in water.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The carbonate concretions occurring at the bottom of Talchir fissile shale facies preserved signatures of various trace fossils along with a cast of doubtful organisms and cyanobacterial mat structures. The host shale deposited under glacial melt water fed lacustrine condition.The concretions,formed in poorly oxygenated ...

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The Suru, Doda and Zanskar river valleys in the semi-arid region of Southern Zanskar Ranges (SZR) preserve a rich repository of the glacial and fluvial landforms, alluvial fans, and lacustrine deposits. Based on detailed field observations, geomorphic mapping and limited optical ages, we suggest four glaciations of ...

Investigation on a system to collect water vapor from the air, for the analysis of natural isotopic variation

International Nuclear Information System (INIS)

Foloni, L.L.

1975-01-01

The development of a system to collect water vapor from air for isotopic composition analysis and its natural variation is studied. The system consists of a molecular sieve type 4A, without cooling agent and permits the choice of a sampling time varying from a few minutes to many hours through the control of the admission vapor flux. The system has been compared with other existing systems, having shown excellent performance for the collection of samples for D/H ratio analysis, with errors of the order of +- -+ 3.0 0 /oo and +- -+ 0.6 0 /oo in the delta sub(D) 0 /oo and delta 18 0 0 /oo ratios, respectively [pt

The global role of health care delivery science: learning from variation to build health systems that avoid waste and harm.

Science.gov (United States)

Mulley, Albert G

2013-09-01

This paper addresses the fourth theme of the Indiana Global Health Research Working Conference, Clinical Effectiveness and Health Systems Research. It explores geographic variation in health care delivery and health outcomes as a source of learning how to achieve better health outcomes at lower cost. It focuses particularly on the relationship between investments made in capacities to deliver different health care services to a population and the value thereby created by that care for individual patients. The framing begins with the dramatic variation in per capita health care expenditures across the nations of the world, which is largely explained by variations in national wealth. The 1978 Declaration of Alma Ata is briefly noted as a response to such inequities with great promise that has not as yet been realized. This failure to realize the promise of Alma Ata grows in significance with the increasing momentum for universal health coverage that is emerging in the current global debate about post-2015 development goals. Drawing upon work done at Dartmouth over more than three decades, the framing then turns to within-country variations in per capita expenditures, utilization of different services, and health outcomes. A case is made for greater attention to the question of value by bringing better information to bear at both the population and individual levels. Specific opportunities to identify and reduce waste in health care, and the harm that is so often associated with it, are identified by learning from outcome variations and practice variations.

SulfoSYS (Sulfolobus Systems Biology) : towards a silicon cell model for the central carbohydrate metabolism of the archaeon Sulfolobus solfataricus under temperature variation

NARCIS (Netherlands)

Albers, Sonja-Verena; Birkeland, Nils-Kare; Driessen, Arnold J. M.; Gertig, Susanne; Haferkamp, Patrick; Klenk, Hans-Peter; Kouril, Theresa; Manica, Andrea; Pham, Trong K.; Ruoff, Peter; Schleper, Christa; Schomburg, Dietmar; Sharkey, Kieran J.; Siebers, Bettina; Sierocinski, Pawel; Steuer, Ralf; van der Oost, John; Westerhoff, Hans V.; Wieloch, Patricia; Wright, Phillip C.; Zaparty, Melanie; Birkeland, Nils-Kåre

SulfoSYS (Sulfolobus Systems Biology) focuses on the study of the CCM (central carbohydrate metabolism) of Sulfolobus solfataricus and its regulation under temperature variation at the systems level. in Archaea, carbohydrates are metabolized by modifications of the classical pathways known from

SulfoSYS (Sulfolobus Systems Biology): towards a silicon cell model for the central carbohydrate metabolism of the archaeon Sulfolobus solfataricus under temperature variation

NARCIS (Netherlands)

Albers, S.V.; Birkeland, N.K.; Driessen, A.J.M.; Gertig, S.; Haferkamp, P.; Klenk, H.P.; Kouril, T.; Manica, A.; Pham, T.K.; Ruoff, P.; Schleper, C.; Schomburg, D.; Sharkey, K.; Siebers, B.; Sierocinski, P.; Steur, R.; Oost, van der J.; Westerhoff, H.V.; Wieloch, P.; Wright, P.C.; Zaparty, M.

2009-01-01

SulfoSYS (Sulfolobus Systems Biology) focuses on the study of the CCM (central carbohydrate metabolism) of Sulfolobus solfataricus and its regulation under temperature variation at the systems level. In Archaea, carbohydrates are metabolized by modifications of the classical pathways known from

Construction of A Trial Function In The Variational Procedure of ...

African Journals Online (AJOL)

A form of variational method for calculating the ground state energy of a quantum mechanical system is considered. The method is based on a systematic construction of a trial variational function at each step of the calculation of the ground state energy. The construction involves introducing more variational parameters to ...

Functional modularity in lake-dwelling characin fishes of Mexico

Directory of Open Access Journals (Sweden)

Claudia Patricia Ornelas-García

2017-09-01

Full Text Available Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi, which are differentiated by their trophic habits. Two different datasets were analyzed: (1 skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2 a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi. Skull shape showed significant differences among species and sex (P < 0.001, where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body, being significant only for A. caballeroi.

Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

Science.gov (United States)

El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

2017-04-01

particles are dispersed, and the suspension is stabilized supported by our SEM observations. In alkaline water, kaolinite reveals a lower degree of consolidation. While, alkaline water has no measurable effect on illite and chlorite surface properties due to the absence of modifications in charge. Illite and chlorite form with other clasts clusters or aggregate structures in suspension when the particle interactions are dominated by attractive energies were formed. The aggregate structure plays a major part in the flow behavior of clay suspensions. Flocs will immobilize the suspending medium, and give rise to increasing viscosity and yield strength of the suspension. S. Hage, A. Hubert-Ferrari, L. Lamair, U. Avşar, M. El Ouahabi, M. Van Daele, F. Boulvain, M.A. Bahri, A. Seret, Al. Plenevaux. Flow dynamics at the origin of thin sandy clay-rich lacustrine turbidites: Examples from Lake Hazar, Turkey, submitted to Sedimentology, in revision.

Variational data assimilation system with nesting model for high resolution ocean circulation

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Yoichi; Igarashi, Hiromichi; Hiyoshi, Yoshimasa; Sasaki, Yuji; Wakamatsu, Tsuyoshi; Awaji, Toshiyuki [Center for Earth Information Science and Technology, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-Ku, Yokohama 236-0001 (Japan); In, Teiji [Japan Marine Science Foundation, 4-24, Minato-cho, Mutsu, Aomori, 035-0064 (Japan); Nakada, Satoshi [Graduate School of Maritime Science, Kobe University, 5-1-1, Fukae-minamimachi, Higashinada-Ku, Kobe, 658-0022 (Japan); Nishina, Kei, E-mail: ishikaway@jamstec.go.jp [Graduate School of Science, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-Ku, Kyoto, 606-8502 (Japan)

2015-10-15

To obtain the high-resolution analysis fields for ocean circulation, a new incremental approach is developed using a four-dimensional variational data assimilation system with nesting models. The results show that there are substantial biases when using a classical method combined with data assimilation and downscaling, caused by different dynamics resulting from the different resolutions of the models used within the nesting models. However, a remarkable reduction in biases of the low-resolution model relative to the high-resolution model was observed using our new approach in narrow strait regions, such as the Tsushima and Tsugaru straits, where the difference in the dynamics represented by the high- and low-resolution models is substantial. In addition, error reductions are demonstrated in the downstream region of these narrow channels associated with the propagation of information through the model dynamics. (paper)

EFFECTS OF PARAMETRIC VARIATIONS ON SEISMIC ANALYSIS METHODS FOR NON-CLASSICALLY DAMPED COUPLED SYSTEMS

International Nuclear Information System (INIS)

XU, J.; DEGRASSI, G.

2000-01-01

A comprehensive benchmark program was developed by Brookhaven National Laboratory (BNL) to perform an evaluation of state-of-the-art methods and computer programs for performing seismic analyses of coupled systems with non-classical damping. The program, which was sponsored by the US Nuclear Regulatory Commission (NRC), was designed to address various aspects of application and limitations of these state-of-the-art analysis methods to typical coupled nuclear power plant (NPP) structures with non-classical damping, and was carried out through analyses of a set of representative benchmark problems. One objective was to examine the applicability of various analysis methods to problems with different dynamic characteristics unique to coupled systems. The examination was performed using parametric variations for three simple benchmark models. This paper presents the comparisons and evaluation of the program participants' results to the BNL exact solutions for the applicable ranges of modeling dynamic characteristic parameters

Variational model for one-dimensional quantum magnets

Science.gov (United States)

Kudasov, Yu. B.; Kozabaranov, R. V.

2018-04-01

A new variational technique for investigation of the ground state and correlation functions in 1D quantum magnets is proposed. A spin Hamiltonian is reduced to a fermionic representation by the Jordan-Wigner transformation. The ground state is described by a new non-local trial wave function, and the total energy is calculated in an analytic form as a function of two variational parameters. This approach is demonstrated with an example of the XXZ-chain of spin-1/2 under a staggered magnetic field. Generalizations and applications of the variational technique for low-dimensional magnetic systems are discussed.

Prototype models for the MOIRA computerised system

Energy Technology Data Exchange (ETDEWEB)

Monte, Luigi [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Hakanson, Lars [Uppsala, Univ. (Sweden). Institute of Earth Sciences; Brittain, John [Oslo, Univ. (Norway). Zoological Museum

1997-06-01

The main aim of the present report is to describe selected models and the principles of the Decision Analysis theory that will be applied to develop the model-based computerised system `MOIRA`. A dose model and a model for predicting radiocaesium migration in lakes and the effects of countermeasures to reduce the contamination levels in the components of lacustrine system are described in detail. The principles for developing prototype models for predicting the migration of {sup 90}Sr in lake abiotic and biotic components are discussed. The environmental models described in the report are based on the use of `collective parameters` which due to mutual compensation effects of different phenomena occurring in complex systems, show low variability when the environmental conditions change. Use of such `collective parameters` not only increases the predictive power of the models, but also increases the practical applicability of the model. Among the main results described in the report, the development of an objective hierarchy table for evaluating the effectiveness of a countermeasure when the economic, social and ecological impacts are accounted for, deserves special attention.

In situ measurement system of electric resistivity for outcrop investigation; Roto de shiyodekiru denkihi teiko keisoku system

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, K; Tamura, T [Osaka City Univ., Osaka (Japan). Faculty of Science; Morikawa, T [Osaka Prefectural Government, Osaka (Japan)

1997-05-27

A simplified electrical resistivity measuring device has been developed as a trial for field and laboratory uses, and some measurements were conducted. For this device, four probe electrodes are penetrated in the clay specimen, to calculate the resistivity from the voltage between both ends of the reference resistance connected with current electrodes in a series and the voltage between intermediate two voltage electrodes. It can be used in the field measurements. For the measurements, specimens of marine and lacustrine clayey sediments with clear stratigraphic levels in southern Osaka Group were used. In the laboratory, in addition to basic physical tests, diatom analysis and measurements of conductivity of clay suspension were also conducted. As a result of the experiments, the electric resistivity of marine clay obtained at the outcrop was lower than lacustrine clay as expected. The value of the former was a half of that of the latter. The frequency dependence in the high frequency region above 1 MHz was the reverse. The difference in electrical resistivity values between non-agitated specimens was about four times. The electrical resistivity of clay suspensions varied in two orders. 3 refs., 9 figs.

Greenhouse gas emissions from the mineralisation process in a Sludge Treatment Reed Bed system: Seasonal variation and environmental impact

DEFF Research Database (Denmark)

Larsen, Julie Dam; Nielsen, Steen; Scheutz, Charlotte

2017-01-01

Greenhouse gas emission data from the mineralisation process in Sludge Treatment Reed Bed systems (STRB) are scarce. The aim of this study was to quantify the emission rates of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and to investigate seasonal variations in order to estimate ...

Efficacy of variational iteration method for chaotic Genesio system - Classical and multistage approach

International Nuclear Information System (INIS)

Goh, S.M.; Noorani, M.S.M.; Hashim, I.

2009-01-01

This is a case study of solving the Genesio system by using the classical variational iteration method (VIM) and a newly modified version called the multistage VIM (MVIM). VIM is an analytical technique that grants us a continuous representation of the approximate solution, which allows better information of the solution over the time interval. Unlike its counterpart, numerical techniques, such as the Runge-Kutta method, provide solutions only at two ends of the time interval (with condition that the selected time interval is adequately small for convergence). Furthermore, it offers approximate solutions in a discretized form, making it complicated in achieving a continuous representation. The explicit solutions through VIM and MVIM are compared with the numerical analysis of the fourth-order Runge-Kutta method (RK4). VIM had been successfully applied to linear and nonlinear systems of non-chaotic in nature and this had been testified by numerous scientists lately. Our intention is to determine whether VIM is also a feasible method in solving a chaotic system like Genesio. At the same time, MVIM will be applied to gauge its accuracy compared to VIM and RK4. Since, for most situations, the validity domain of the solutions is often an issue, we will consider a reasonably large time frame in our work.

Presymplectic current and the inverse problem of the calculus of variations

NARCIS (Netherlands)

Khavkine, I.

2013-01-01

The inverse problem of the calculus of variations asks whether a given system of partial differential equations (PDEs) admits a variational formulation. We show that the existence of a presymplectic form in the variational bicomplex, when horizontally closed on solutions, allows us to construct a

Cost variation in a laparoscopic cholecystectomy and the association with outcomes across a single health system: implications for standardization and improved resource utilization

Science.gov (United States)

Brauer, David G; Hawkins, William G; Strasberg, Steven M; Brunt, L Michael; Jaques, David P; Mercurio, Nicholas R; Hall, Bruce L; Fields, Ryan C

2015-01-01

Background Payers and regulatory bodies are increasingly placing emphasis on cost containment, quality/outcome measurement and transparent reporting. Significant cost variation occurs in many operative procedures without a clear relationship with outcomes. Clear cost-benefit associations will be necessary to justify expenditures in the era of bundled payment structures. Methods All laparoscopic cholecystectomies (LCCKs) performed within a single health system over a 1-year period were analysed for operating room (OR) supply cost. The cost was correlated with American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) outcomes. Results From July 2013 to June 2014, 2178 LCCKs were performed by 55 surgeons at seven hospitals. The median case OR supply cost was $513 ± 156. There was variation in cost between individual surgeons and within an individual surgeon's practice. There was no correlation between cost and ACS NSQIP outcomes. The majority of cost variation was explained by selection of trocar and clip applier constructs. Conclusions Significant case OR cost variation is present in LCCK across a single health system, and there is no clear association between increased cost and NSQIP outcomes. Placed within the larger context of overall cost, the opportunity exists for improved resource utilization with no obvious risk for a reduction in the quality of care. PMID:26345351

Variational Monte Carlo Method with Dirichlet Boundary Conditions: Application to the Study of Confined Systems by Impenetrable Surfaces with Different Symmetries.

Science.gov (United States)

Sarsa, Antonio; Le Sech, Claude

2011-09-13

Variational Monte Carlo method is a powerful tool to determine approximate wave functions of atoms, molecules, and solids up to relatively large systems. In the present work, we extend the variational Monte Carlo approach to study confined systems. Important properties of the atoms, such as the spatial distribution of the electronic charge, the energy levels, or the filling of electronic shells, are modified under confinement. An expression of the energy very similar to the estimator used for free systems is derived. This opens the possibility to study confined systems with little changes in the solution of the corresponding free systems. This is illustrated by the study of helium atom in its ground state (1)S and the first (3)S excited state confined by spherical, cylindrical, and plane impenetrable surfaces. The average interelectronic distances are also calculated. They decrease in general when the confinement is stronger; however, it is seen that they present a minimum for excited states under confinement by open surfaces (cylindrical, planes) around the radii values corresponding to ionization. The ground (2)S and the first (2)P and (2)D excited states of the lithium atom are calculated under spherical constraints for different confinement radii. A crossing between the (2)S and (2)P states is observed around rc = 3 atomic units, illustrating the modification of the atomic energy level under confinement. Finally the carbon atom is studied in the spherical symmetry by using both variational and diffusion Monte Carlo methods. It is shown that the hybridized state sp(3) becomes lower in energy than the ground state (3)P due to a modification and a mixing of the atomic orbitals s, p under strong confinement. This result suggests a model, at least of pedagogical interest, to interpret the basic properties of carbon atom in chemistry.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The contents of Ti, Al and Fe₂O₃ in a lacustrine sediment core (DY6) collected from Dongdao Island, South China Sea (SCS), were determined to be much higher than those in the three major sediment endmembers (coral sand, guano and plants), and their likely sources include terrigenous dust and volcanic ash.

Variational Algorithms for Test Particle Trajectories

Science.gov (United States)

Ellison, C. Leland; Finn, John M.; Qin, Hong; Tang, William M.

2015-11-01

The theory of variational integration provides a novel framework for constructing conservative numerical methods for magnetized test particle dynamics. The retention of conservation laws in the numerical time advance captures the correct qualitative behavior of the long time dynamics. For modeling the Lorentz force system, new variational integrators have been developed that are both symplectic and electromagnetically gauge invariant. For guiding center test particle dynamics, discretization of the phase-space action principle yields multistep variational algorithms, in general. Obtaining the desired long-term numerical fidelity requires mitigation of the multistep method's parasitic modes or applying a discretization scheme that possesses a discrete degeneracy to yield a one-step method. Dissipative effects may be modeled using Lagrange-D'Alembert variational principles. Numerical results will be presented using a new numerical platform that interfaces with popular equilibrium codes and utilizes parallel hardware to achieve reduced times to solution. This work was supported by DOE Contract DE-AC02-09CH11466.

Variation in broccoli cultivar phytochemical content under organic and conventional management systems: implications in breeding for nutrition.

Science.gov (United States)

Renaud, Erica N C; Lammerts van Bueren, Edith T; Myers, James R; Paulo, Maria João; van Eeuwijk, Fred A; Zhu, Ning; Juvik, John A

2014-01-01

Organic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine). The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (δ-, γ-, α-tocopherol) and carotenoids (lutein, zeaxanthin, β-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For δ- and γ-tocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype (8.41-13.03%) was the largest source of variation and its interactions with location and season. Overall, phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F1 hybrids. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1 hybrids. We identified distinct locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were correlated with one another. Little or no association between

Long scale astronomical variations in our solar system: consequences for future ice ages

International Nuclear Information System (INIS)

Edvardsson, S.; Karlsson, K.G.

2002-01-01

It is well known that the Earth has gone through a number of glaciations during the last few million years. It is generally agreed that changes in the Earth's orbital parameters and obliquity play an important role in climate forcing, an idea originally due to Milutin Milankovitch. The climatic history of the Earth shows clear evidence of the precession periods (about 19 000 and 23 000 years) and changes in the obliquity (period about 41 000 years). The main period in glacial data (around 100 000 years) is, however, hard to explain in terms of orbital variations. During the last decade or so a large number of simulations of the planetary system have been reported, many of which have been concerned with the influence of variations in the Earth's orbit on climate. In former studies comparisons have been made between the astronomical parameters and the ice volume of the Earth. Generally speaking, the match between astronomical forcing and ice data has been rather poor. In this study we instead compare the parameters with changes in ice volume, which yields a much better agreement between the astronomical and the geological data. A number of climate models have been constructed to reproduce past climate history, and also to make predictions about the future. These are purely empirical models designed to match certain periods of past climate. Typically they also involve a substantial number of free parameters. (authors)

Milk Production in the Sylvopastoral Zone of Senegal: Variation Factors and Local Populations’ Management System

Directory of Open Access Journals (Sweden)

A. T. Diop

2009-01-01

Full Text Available In the Sahelian region of Senegal, milk production in pastoral systems is subjected to inter- and intra-annual variations because the animal feed is almost exclusively based on natural resources. Studies conducted from a monitoring set-up in pastoralist settlements and in station, and data from Nestle Company have shown that milk production was highly related to the milk collection date, but with a low correlation with the total amount of rainfall. The relationship between total milk production and the normalized difference vegetation index (NDVI was polynomial. The production peak was reached when the water content in forage was 70%. Surveys on pastoralists (men and women belonging to different ethnic groups and living in different production subsystems (Walo, Djoloff and Ferlo showed that the duration of lactation, number of cows and animal species were the main factors of variation of milk production. The actors in charge of milk production management differed depending on the ethnic group. Milk curdling and butter making were the two preserving methods used, and five types of gourds were used in the process. Dairy products still held a major place in farmers’ incomes and skim milk curd was the most marketed product.

Sea level and climate variations

NARCIS (Netherlands)

Oerlemans, J.

1985-01-01

Review paper, ESA Symposium on Application of Satellite Data to Climate Modelling. Alpbach (Austria) Sea level is an essential component of the climate system, on which many human activities in the coastal zone depend. Climate variations leading to changes in relative sea level are

Variational principles of continuum mechanics. Vol. 1. Fundamentals

Energy Technology Data Exchange (ETDEWEB)

Berdichevsky, Victor L. [Wayne State Univ., Detroit, MI (United States). Dept. of Mechanical Engineering

2009-07-01

The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems. Berdichevsky's work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given. In this book, the first volume, the author covers the variational principles for systems with a finite number of degrees of freedom; the variational principles of thermodynamics; the basics of continuum mechanics; the variational principles for classical models of continuum mechanics, such as elastic and plastic bodies, and ideal and viscous fluids; and direct methods of calculus of variations. (orig.)

Genetic variation and activity of the renin-angiotensin system and severe hypoglycemia in type 1 diabetes

DEFF Research Database (Denmark)

Pedersen-Bjergaard, U.; Dhamrait, S.S.; Sethi, A.A.

2008-01-01

BACKGROUND: The deletion-allele of the angiotensin-converting enzyme (ACE) gene and elevated ACE activity are associated with increased risk of severe hypoglycemia in type 1 diabetes. We explored whether genetic and phenotypic variations in other components of the renin-angiotensin system...... are similarly associated. METHODS: Episodes of severe hypoglycemia were recorded in 171 consecutive type 1 diabetic outpatients during a 1-year follow-up. Participants were characterized at baseline by gene polymorphisms in angiotensinogen, ACE, angiotensin-II receptor types 1 (AT1R) and 2 (AT2R), and by plasma...... associate with high risk of severe hypoglycemia in type 1 diabetes. A potential preventive effect of renin-angiotensin system blocking drugs in patients with recurrent severe hypoglycemia merits further investigation Udgivelsesdato: 2008/3...

Prezygotic barriers to hybridization in marine broadcast spawners: reproductive timing and mating system variation.

Directory of Open Access Journals (Sweden)

Carla A Monteiro

Full Text Available Sympatric assemblages of congeners with incomplete reproductive barriers offer the opportunity to study the roles that ecological and non-ecological factors play in reproductive isolation. While interspecific asynchrony in gamete release and gametic incompatibility are known prezygotic barriers to hybridization, the role of mating system variation has been emphasized in plants. Reproductive isolation between the sibling brown algal species Fucus spiralis, Fucus guiryi (selfing hermaphrodite and Fucus vesiculosus (dioecious was studied because they form hybrids in parapatry in the rocky intertidal zone, maintain species integrity over a broad geographic range, and have contrasting mating systems. We compared reproductive synchrony (spawning overlap between the three species at several temporal scales (yearly/seasonal, semilunar/tidal, and hourly during single tides. Interspecific patterns of egg release were coincident at seasonal (single peak in spring to early summer to semilunar timescales. Synthesis of available data indicated that spawning is controlled by semidiurnal tidal and daily light-dark cues, and not directly by semilunar cycles. Importantly, interspecific shifts in timing detected at the hourly scale during single tides were consistent with a partial ecological prezygotic hybridization barrier. The species displayed patterns of gamete release consistent with a power law distribution, indicating a high degree of reproductive synchrony, while the hypothesis of weaker selective constraints for synchrony in selfing versus outcrossing species was supported by observed spawning in hermaphrodites over a broader range of tidal phase than in outcrossers. Synchronous gamete release is critical to the success of external fertilization, while high-energy intertidal environments may offer only limited windows of reproductive opportunity. Within these windows, however, subtle variations in reproductive timing have evolved with the potential to

Perspective: Maximum caliber is a general variational principle for dynamical systems.

Science.gov (United States)

Dixit, Purushottam D; Wagoner, Jason; Weistuch, Corey; Pressé, Steve; Ghosh, Kingshuk; Dill, Ken A

2018-01-07

We review here Maximum Caliber (Max Cal), a general variational principle for inferring distributions of paths in dynamical processes and networks. Max Cal is to dynamical trajectories what the principle of maximum entropy is to equilibrium states or stationary populations. In Max Cal, you maximize a path entropy over all possible pathways, subject to dynamical constraints, in order to predict relative path weights. Many well-known relationships of non-equilibrium statistical physics-such as the Green-Kubo fluctuation-dissipation relations, Onsager's reciprocal relations, and Prigogine's minimum entropy production-are limited to near-equilibrium processes. Max Cal is more general. While it can readily derive these results under those limits, Max Cal is also applicable far from equilibrium. We give examples of Max Cal as a method of inference about trajectory distributions from limited data, finding reaction coordinates in bio-molecular simulations, and modeling the complex dynamics of non-thermal systems such as gene regulatory networks or the collective firing of neurons. We also survey its basis in principle and some limitations.

Perspective: Maximum caliber is a general variational principle for dynamical systems

Science.gov (United States)

Dixit, Purushottam D.; Wagoner, Jason; Weistuch, Corey; Pressé, Steve; Ghosh, Kingshuk; Dill, Ken A.

2018-01-01

We review here Maximum Caliber (Max Cal), a general variational principle for inferring distributions of paths in dynamical processes and networks. Max Cal is to dynamical trajectories what the principle of maximum entropy is to equilibrium states or stationary populations. In Max Cal, you maximize a path entropy over all possible pathways, subject to dynamical constraints, in order to predict relative path weights. Many well-known relationships of non-equilibrium statistical physics—such as the Green-Kubo fluctuation-dissipation relations, Onsager's reciprocal relations, and Prigogine's minimum entropy production—are limited to near-equilibrium processes. Max Cal is more general. While it can readily derive these results under those limits, Max Cal is also applicable far from equilibrium. We give examples of Max Cal as a method of inference about trajectory distributions from limited data, finding reaction coordinates in bio-molecular simulations, and modeling the complex dynamics of non-thermal systems such as gene regulatory networks or the collective firing of neurons. We also survey its basis in principle and some limitations.

Application of the stochastic variational method to the calculation of 3α- and 4α-systems

International Nuclear Information System (INIS)

Kukulin, V.I.; Krasnopol'skii, V.M.

1975-01-01

The results of calculations of the properties of 3α- and 4α-systems carried out within the framework of the recently suggested stochastic variational method are presented. As the α-α potentials, two different types of potentials are used: the Ali-Bodmer repulsive core potential and the deep attractive α-α potential with forbidden states. In the latter case the pseudopotential approach we have earlier suggested is used. The energies of levels, (r 2 ) and form-factors of the ground state F(q 2 ) are calculated

Partitioning of genetic variation between regulatory and coding gene segments: the predominance of software variation in genes encoding introvert proteins.

Science.gov (United States)

Mitchison, A

1997-01-01

In considering genetic variation in eukaryotes, a fundamental distinction can be made between variation in regulatory (software) and coding (hardware) gene segments. For quantitative traits the bulk of variation, particularly that near the population mean, appears to reside in regulatory segments. The main exceptions to this rule concern proteins which handle extrinsic substances, here termed extrovert proteins. The immune system includes an unusually large proportion of this exceptional category, but even so its chief source of variation may well be polymorphism in regulatory gene segments. The main evidence for this view emerges from genome scanning for quantitative trait loci (QTL), which in the case of the immune system points to a major contribution of pro-inflammatory cytokine genes. Further support comes from sequencing of major histocompatibility complex (Mhc) class II promoters, where a high level of polymorphism has been detected. These Mhc promoters appear to act, in part at least, by gating the back-signal from T cells into antigen-presenting cells. Both these forms of polymorphism are likely to be sustained by the need for flexibility in the immune response. Future work on promoter polymorphism is likely to benefit from the input from genome informatics.

Variation and management of the tertiary and industrial lightning; Variation et gestion de l'eclairage tertiaire et industriel

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-02-01

This document provides information on the systems of possibilities of power variation and their management for an industrial lightning in the ternary sector. These systems bring to the user more comfort and improve the global and environmental cost of the installations. (A.L.B.)

In silico detection of sequence variations modifying transcriptional regulation.

Directory of Open Access Journals (Sweden)

Malin C Andersen

2008-01-01

Full Text Available Identification of functional genetic variation associated with increased susceptibility to complex diseases can elucidate genes and underlying biochemical mechanisms linked to disease onset and progression. For genes linked to genetic diseases, most identified causal mutations alter an encoded protein sequence. Technological advances for measuring RNA abundance suggest that a significant number of undiscovered causal mutations may alter the regulation of gene transcription. However, it remains a challenge to separate causal genetic variations from linked neutral variations. Here we present an in silico driven approach to identify possible genetic variation in regulatory sequences. The approach combines phylogenetic footprinting and transcription factor binding site prediction to identify variation in candidate cis-regulatory elements. The bioinformatics approach has been tested on a set of SNPs that are reported to have a regulatory function, as well as background SNPs. In the absence of additional information about an analyzed gene, the poor specificity of binding site prediction is prohibitive to its application. However, when additional data is available that can give guidance on which transcription factor is involved in the regulation of the gene, the in silico binding site prediction improves the selection of candidate regulatory polymorphisms for further analyses. The bioinformatics software generated for the analysis has been implemented as a Web-based application system entitled RAVEN (regulatory analysis of variation in enhancers. The RAVEN system is available at http://www.cisreg.ca for all researchers interested in the detection and characterization of regulatory sequence variation.

In Silico Detection of Sequence Variations Modifying Transcriptional Regulation

Science.gov (United States)

Andersen, Malin C; Engström, Pär G; Lithwick, Stuart; Arenillas, David; Eriksson, Per; Lenhard, Boris; Wasserman, Wyeth W; Odeberg, Jacob

2008-01-01

Identification of functional genetic variation associated with increased susceptibility to complex diseases can elucidate genes and underlying biochemical mechanisms linked to disease onset and progression. For genes linked to genetic diseases, most identified causal mutations alter an encoded protein sequence. Technological advances for measuring RNA abundance suggest that a significant number of undiscovered causal mutations may alter the regulation of gene transcription. However, it remains a challenge to separate causal genetic variations from linked neutral variations. Here we present an in silico driven approach to identify possible genetic variation in regulatory sequences. The approach combines phylogenetic footprinting and transcription factor binding site prediction to identify variation in candidate cis-regulatory elements. The bioinformatics approach has been tested on a set of SNPs that are reported to have a regulatory function, as well as background SNPs. In the absence of additional information about an analyzed gene, the poor specificity of binding site prediction is prohibitive to its application. However, when additional data is available that can give guidance on which transcription factor is involved in the regulation of the gene, the in silico binding site prediction improves the selection of candidate regulatory polymorphisms for further analyses. The bioinformatics software generated for the analysis has been implemented as a Web-based application system entitled RAVEN (regulatory analysis of variation in enhancers). The RAVEN system is available at http://www.cisreg.ca for all researchers interested in the detection and characterization of regulatory sequence variation. PMID:18208319

Variational multiscale models for charge transport.

Science.gov (United States)

Wei, Guo-Wei; Zheng, Qiong; Chen, Zhan; Xia, Kelin

2012-01-01

This work presents a few variational multiscale models for charge transport in complex physical, chemical and biological systems and engineering devices, such as fuel cells, solar cells, battery cells, nanofluidics, transistors and ion channels. An essential ingredient of the present models, introduced in an earlier paper (Bulletin of Mathematical Biology, 72, 1562-1622, 2010), is the use of differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic domain from the microscopic domain, meanwhile, dynamically couple discrete and continuum descriptions. Our main strategy is to construct the total energy functional of a charge transport system to encompass the polar and nonpolar free energies of solvation, and chemical potential related energy. By using the Euler-Lagrange variation, coupled Laplace-Beltrami and Poisson-Nernst-Planck (LB-PNP) equations are derived. The solution of the LB-PNP equations leads to the minimization of the total free energy, and explicit profiles of electrostatic potential and densities of charge species. To further reduce the computational complexity, the Boltzmann distribution obtained from the Poisson-Boltzmann (PB) equation is utilized to represent the densities of certain charge species so as to avoid the computationally expensive solution of some Nernst-Planck (NP) equations. Consequently, the coupled Laplace-Beltrami and Poisson-Boltzmann-Nernst-Planck (LB-PBNP) equations are proposed for charge transport in heterogeneous systems. A major emphasis of the present formulation is the consistency between equilibrium LB-PB theory and non-equilibrium LB-PNP theory at equilibrium. Another major emphasis is the capability of the reduced LB-PBNP model to fully recover the prediction of the LB-PNP model at non-equilibrium settings. To account for the fluid impact on the charge transport, we derive coupled Laplace-Beltrami, Poisson-Nernst-Planck and Navier-Stokes equations from the variational principle

Variational multiscale models for charge transport

Science.gov (United States)

Wei, Guo-Wei; Zheng, Qiong; Chen, Zhan; Xia, Kelin

2012-01-01

This work presents a few variational multiscale models for charge transport in complex physical, chemical and biological systems and engineering devices, such as fuel cells, solar cells, battery cells, nanofluidics, transistors and ion channels. An essential ingredient of the present models, introduced in an earlier paper (Bulletin of Mathematical Biology, 72, 1562-1622, 2010), is the use of differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic domain from the microscopic domain, meanwhile, dynamically couple discrete and continuum descriptions. Our main strategy is to construct the total energy functional of a charge transport system to encompass the polar and nonpolar free energies of solvation, and chemical potential related energy. By using the Euler-Lagrange variation, coupled Laplace-Beltrami and Poisson-Nernst-Planck (LB-PNP) equations are derived. The solution of the LB-PNP equations leads to the minimization of the total free energy, and explicit profiles of electrostatic potential and densities of charge species. To further reduce the computational complexity, the Boltzmann distribution obtained from the Poisson-Boltzmann (PB) equation is utilized to represent the densities of certain charge species so as to avoid the computationally expensive solution of some Nernst-Planck (NP) equations. Consequently, the coupled Laplace-Beltrami and Poisson-Boltzmann-Nernst-Planck (LB-PBNP) equations are proposed for charge transport in heterogeneous systems. A major emphasis of the present formulation is the consistency between equilibrium LB-PB theory and non-equilibrium LB-PNP theory at equilibrium. Another major emphasis is the capability of the reduced LB-PBNP model to fully recover the prediction of the LB-PNP model at non-equilibrium settings. To account for the fluid impact on the charge transport, we derive coupled Laplace-Beltrami, Poisson-Nernst-Planck and Navier-Stokes equations from the variational principle

Disentangling the effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass in dry zone homegarden agroforestry systems.

Science.gov (United States)

Ali, Arshad; Mattsson, Eskil

2017-11-15

The biodiversity - aboveground biomass relationship has been intensively studied in recent decades. However, no consensus has been arrived to consider the interplay of species diversity, and intraspecific and interspecific tree size variation in driving aboveground biomass, after accounting for the effects of plot size heterogeneity, soil fertility and stand quality in natural forest including agroforests. We tested the full, partial and no mediations effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass by employing structural equation models (SEMs) using data from 45 homegarden agroforestry systems in Sri Lanka. The full mediation effect of either species diversity or intraspecific and interspecific tree size variation was rejected, while the partial and no mediation effects were accepted. In the no mediation SEM, homegarden size had the strongest negative direct effect (β=-0.49) on aboveground biomass (R 2 =0.65), followed by strong positive direct effect of intraspecific tree size variation (β=0.32), species diversity (β=0.29) and interspecific tree size variation (β=0.28). Soil fertility had a negative direct effect on interspecific tree size variation (β=-0.31). Stand quality had a significant positive total effect on aboveground biomass (β=0.28), but homegarden size had a significant negative total effect (β=-0.62), while soil fertility had a non-significant total effect on aboveground biomass. Similar to the no mediation SEM, the partial mediation SEMs had explained almost similar variation in aboveground biomass because species diversity, and intraspecific and interspecific tree size variation had non-significant indirect effects on aboveground biomass via each other. Our results strongly suggest that a multilayered tree canopy structure, due to high intraspecific and interspecific tree size variation, increases light capture and efficient utilization of resources among component species, and

Trophic preference and preliminary indication of phylloplane fungal influence on the diet of the non-native Gammarus roeselii Gervais 1835 (Amphipoda, Gammaridae in the sub-lacustrine Ticino river basin (Lombardy, Northern Italy

Directory of Open Access Journals (Sweden)

Daniele Paganelli

2017-03-01

Full Text Available Gammarids are one of the most successful invaders in freshwater ecosystems due to both their diet plasticity and high reproductive capacity. One such amphipod, Gammarus roeselii, has recently colonised the southern part of the sub-lacustrine Ticino River basin (Northern Italy, where its ecological niche overlaps with the native species Echinogammarus stammeri. In the present paper the food preferences of G. roeselii have been investigated, testing the palatability of different food sources: three macrophytes and three different leaf debris. Moreover, an explorative mycological analysis on the three different leaf debris used in the experiment has been performed. Results of the short-term experiment suggest that aquatic plants are less palatable than allocthonous detritus, probably because they can contain secondary metabolites (i.e. tannins and they have lower nutrient tissues with very high water content. On the contrary, G. roeselii showed a clear preference for the oak leaves, resulted colonized by a more abundant fungal biomass and, therefore, more palatable too.

Glaciolacustrine deposits formed in an ice-dammed tributary valley in the south-central Pyrenees: New evidence for late Pleistocene climate

Science.gov (United States)

Sancho, Carlos; Arenas, Concha; Pardo, Gonzalo; Peña-Monné, José Luis; Rhodes, Edward J.; Bartolomé, Miguel; García-Ruiz, José M.; Martí-Bono, Carlos

2018-04-01

Combined geomorphic features, stratigraphic characteristics and sedimentologic interpretation, coupled with optically stimulated luminescence (OSL) dates, of a glacio-fluvio-lacustrine sequence (Linás de Broto, northern Spain) provide new information to understand the palaeoenvironmental significance of dynamics of glacier systems in the south-central Pyrenees during the Last Glacial Cycle (≈130 ka to 14 ka). The Linás de Broto depositional system consisted of a proglacial lake fed primarily by meltwater streams emanating from the small Sorrosal glacier and dammed by a lateral moraine of the Ara trunk glacier. The resulting glacio-fluvio-lacustrine sequence, around 55 m thick, is divided into five lithological units consisting of braided fluvial (gravel deposits), lake margin (gravel and sand deltaic deposits) and distal lake (silt and clay laminites) facies associations. Evolution of the depositional environment reflects three phases of progradation of a high-energy braided fluvial system separated by two phases of rapid expansion of the lake. Fluvial progradation occurred during short periods of ice melting. Lake expansion concurred with ice-dam growth of the trunk glacier. The first lake expansion occurred over a time range between 55 ± 9 ka and 49 ± 11 ka, and is consistent with the age of the Viu lateral moraine (49 ± 8 ka), which marks the maximum areal extent of the Ara glacier during the Last Glacial Cycle. These dates confirm that the maximum areal extent of the glacier occurred during Marine Isotope Stages 4 and 3 in the south-central Pyrenees, thus before the Last Glacial Maximum. The evolution of the Linás de Broto depositional system during this maximum glacier extent was modulated by climate oscillations in the northern Iberian Peninsula, probably related to latitudinal shifts of the atmospheric circulation in the southern North-Atlantic Ocean, and variations in summer insolation intensity.

Calculus of variations

CERN Document Server

Elsgolc, L E; Stark, M

1961-01-01

Calculus of Variations aims to provide an understanding of the basic notions and standard methods of the calculus of variations, including the direct methods of solution of the variational problems. The wide variety of applications of variational methods to different fields of mechanics and technology has made it essential for engineers to learn the fundamentals of the calculus of variations. The book begins with a discussion of the method of variation in problems with fixed boundaries. Subsequent chapters cover variational problems with movable boundaries and some other problems; sufficiency

Speculative petroleum systems of the Punta del Este Basin (offshore Uruguay

Directory of Open Access Journals (Sweden)

Ethel Morales

Full Text Available ABSTRACT: The Uruguayan continental margin was generated as the result of the breakup of Gondwana and, later, the opening of the South Atlantic Ocean, which began in the Jurassic. Three major areas of Meso-Cenozoic sedimentation are located in the Uruguayan offshore: the Punta del Este Basin, the southernmost sector of the Pelotas Basin and the Oriental del Plata Basin. These basins share the classical stages of tectono-sedimentary evolution of the other Atlantic basins, including the prerift (Paleozoic, rift (Jurassic-Early Cretaceous, transition (Barremian-Aptian and postrift (Aptian-present phases. Based on the analysis of basin evolution through seismic sections and well data as well as on the establishment of analogies with productive Atlantic basins, four speculative petroleum systems are proposed for the Punta del Este Basin: 1 Marine petroleum system of the prerift stage: Devonian/Permian-Devonian/Permian(?, 2 Lacustrine petroleum system of the synrift stage: Neocomian-Neocomian(?, 3 Marine petroleum system of the Cretaceous postrift: Aptian-Late Cretaceous(?, 4 Marine petroleum system of the Cenozoic postrift: Paleocene-Paleogene/Neogene(?.

A general maximum entropy framework for thermodynamic variational principles

International Nuclear Information System (INIS)

Dewar, Roderick C.

2014-01-01

Minimum free energy principles are familiar in equilibrium thermodynamics, as expressions of the second law. They also appear in statistical mechanics as variational approximation schemes, such as the mean-field and steepest-descent approximations. These well-known minimum free energy principles are here unified and extended to any system analyzable by MaxEnt, including non-equilibrium systems. The MaxEnt Lagrangian associated with a generic MaxEnt distribution p defines a generalized potential Ψ for an arbitrary probability distribution p-hat, such that Ψ is a minimum at (p-hat) = p. Minimization of Ψ with respect to p-hat thus constitutes a generic variational principle, and is equivalent to minimizing the Kullback-Leibler divergence between p-hat and p. Illustrative examples of min–Ψ are given for equilibrium and non-equilibrium systems. An interpretation of changes in Ψ is given in terms of the second law, although min–Ψ itself is an intrinsic variational property of MaxEnt that is distinct from the second law

A general maximum entropy framework for thermodynamic variational principles

Energy Technology Data Exchange (ETDEWEB)

Dewar, Roderick C., E-mail: roderick.dewar@anu.edu.au [Research School of Biology, The Australian National University, Canberra ACT 0200 (Australia)

2014-12-05

Minimum free energy principles are familiar in equilibrium thermodynamics, as expressions of the second law. They also appear in statistical mechanics as variational approximation schemes, such as the mean-field and steepest-descent approximations. These well-known minimum free energy principles are here unified and extended to any system analyzable by MaxEnt, including non-equilibrium systems. The MaxEnt Lagrangian associated with a generic MaxEnt distribution p defines a generalized potential Ψ for an arbitrary probability distribution p-hat, such that Ψ is a minimum at (p-hat) = p. Minimization of Ψ with respect to p-hat thus constitutes a generic variational principle, and is equivalent to minimizing the Kullback-Leibler divergence between p-hat and p. Illustrative examples of min–Ψ are given for equilibrium and non-equilibrium systems. An interpretation of changes in Ψ is given in terms of the second law, although min–Ψ itself is an intrinsic variational property of MaxEnt that is distinct from the second law.

Anatomical variations of the celiac trunk and hepatic arterial system: an analysis using multidetector computed tomography angiography

International Nuclear Information System (INIS)

Araujo Neto, Severino Aires; Franca, Henrique Almeida; Mello Junior, Carlos Fernando de; Silva Neto, Eulampio Jose; Negromonte, Gustavo Ramalho Pessoa; Duarte, Claudia Martina Araujo; Cavalcanti Neto, Bartolomeu Fragoso; Farias, Rebeca Danielly da Fonseca

2015-01-01

Objective: To analyze the prevalence of anatomical variations of celiac arterial trunk (CAT) branches and hepatic arterial system (HAS), as well as the CAT diameter, length and distance to the superior mesenteric artery. Materials And Methods: Retrospective, cross-sectional and predominantly descriptive study based on the analysis of multidetector computed tomography images of 60 patients. Results: The celiac trunk anatomy was normal in 90% of cases. Hepatosplenic trunk was found in 8.3% of patients, and hepatogastric trunk in 1.7%. Variation of the HAS was observed in 21.7% of cases, including anomalous location of the right hepatic artery in 8.3% of cases, and of the left hepatic artery, in 5%. Also, cases of joint relocation of right and left hepatic arteries, and trifurcation of the proper hepatic artery were observed, respectively, in 3 (5%) and 2 (3.3%) patients. Mean length and caliber of the CAT were 2.3 cm and 0.8 cm, respectively. Mean distance between CAT and superior mesenteric artery was 1.2 cm (standard deviation = 4.08). A significant correlation was observed between CAT diameter and length, and CAT diameter and distance to superior mesenteric artery. Conclusion: The pattern of CAT variations and diameter corroborate the majority of the literature data. However, this does not happen in relation to the HAS. (author)

Anatomical variations of the celiac trunk and hepatic arterial system: an analysis using multidetector computed tomography angiography

Energy Technology Data Exchange (ETDEWEB)

Araujo Neto, Severino Aires; Franca, Henrique Almeida; Mello Junior, Carlos Fernando de; Silva Neto, Eulampio Jose; Negromonte, Gustavo Ramalho Pessoa; Duarte, Claudia Martina Araujo; Cavalcanti Neto, Bartolomeu Fragoso; Farias, Rebeca Danielly da Fonseca, E-mail: severinoaires@hotmail.com [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil)

2015-11-15

Objective: To analyze the prevalence of anatomical variations of celiac arterial trunk (CAT) branches and hepatic arterial system (HAS), as well as the CAT diameter, length and distance to the superior mesenteric artery. Materials And Methods: Retrospective, cross-sectional and predominantly descriptive study based on the analysis of multidetector computed tomography images of 60 patients. Results: The celiac trunk anatomy was normal in 90% of cases. Hepatosplenic trunk was found in 8.3% of patients, and hepatogastric trunk in 1.7%. Variation of the HAS was observed in 21.7% of cases, including anomalous location of the right hepatic artery in 8.3% of cases, and of the left hepatic artery, in 5%. Also, cases of joint relocation of right and left hepatic arteries, and trifurcation of the proper hepatic artery were observed, respectively, in 3 (5%) and 2 (3.3%) patients. Mean length and caliber of the CAT were 2.3 cm and 0.8 cm, respectively. Mean distance between CAT and superior mesenteric artery was 1.2 cm (standard deviation = 4.08). A significant correlation was observed between CAT diameter and length, and CAT diameter and distance to superior mesenteric artery. Conclusion: The pattern of CAT variations and diameter corroborate the majority of the literature data. However, this does not happen in relation to the HAS. (author)

Using the amplitude variation of a reverberation chamber channel to predict the synchronization of a wireless digital communication test system

NARCIS (Netherlands)

Tanuhardja, Ray R.; Gonzalez, Luis A.; Wang, Chih-Ming; Young, William F.; Remley, Kate A.; Ladbury, John M.

2015-01-01

We discuss the use of a metric based on the amplitude variation of a channel in the signal bandwidth to predict whether or not a digital wireless communication test system receiver will be able to demodulate a test signal. This metric is compared to another method consisting of the correlation

Stability Analysis and Variational Integrator for Real-Time Formation Based on Potential Field

Directory of Open Access Journals (Sweden)

Shengqing Yang

2014-01-01

Full Text Available This paper investigates a framework of real-time formation of autonomous vehicles by using potential field and variational integrator. Real-time formation requires vehicles to have coordinated motion and efficient computation. Interactions described by potential field can meet the former requirement which results in a nonlinear system. Stability analysis of such nonlinear system is difficult. Our methodology of stability analysis is discussed in error dynamic system. Transformation of coordinates from inertial frame to body frame can help the stability analysis focus on the structure instead of particular coordinates. Then, the Jacobian of reduced system can be calculated. It can be proved that the formation is stable at the equilibrium point of error dynamic system with the effect of damping force. For consideration of calculation, variational integrator is introduced. It is equivalent to solving algebraic equations. Forced Euler-Lagrange equation in discrete expression is used to construct a forced variational integrator for vehicles in potential field and obstacle environment. By applying forced variational integrator on computation of vehicles' motion, real-time formation of vehicles in obstacle environment can be implemented. Algorithm based on forced variational integrator is designed for a leader-follower formation.

Prevalence and variation of Chronic Kidney Disease in the Irish health system: initial findings from the National Kidney Disease Surveillance Programme.

LENUS (Irish Health Repository)

Stack, Austin G

2014-01-01

Chronic Kidney Disease (CKD) is a major non-communicable chronic disease that is associated with adverse clinical and economic outcomes. Passive surveillance systems are likely to improve efforts for prevention of chronic kidney disease (CKD) and inform national service planning. This study was conducted to determine the overall prevalence of CKD in the Irish health system, assess period trends and explore patterns of variation as part of a novel surveillance initiative.

SYSTEMATIC AND STOCHASTIC VARIATIONS IN PULSAR DISPERSION MEASURES

International Nuclear Information System (INIS)

Lam, M. T.; Cordes, J. M.; Chatterjee, S.; Jones, M. L.; McLaughlin, M. A.; Armstrong, J. W.

2016-01-01

We analyze deterministic and random temporal variations in the dispersion measure (DM) from the full three-dimensional velocities of pulsars with respect to the solar system, combined with electron-density variations over a wide range of length scales. Previous treatments have largely ignored pulsars’ changing distances while favoring interpretations involving changes in sky position from transverse motion. Linear trends in pulsar DMs observed over 5–10 year timescales may signify sizable DM gradients in the interstellar medium (ISM) sampled by the changing direction of the line of sight to the pulsar. We show that motions parallel to the line of sight can also account for linear trends, for the apparent excess of DM variance over that extrapolated from scintillation measurements, and for the apparent non-Kolmogorov scalings of DM structure functions inferred in some cases. Pulsar motions through atomic gas may produce bow-shock ionized gas that also contributes to DM variations. We discuss the possible causes of periodic or quasi-periodic changes in DM, including seasonal changes in the ionosphere, annual variations of the solar elongation angle, structure in the heliosphere and ISM boundary, and substructure in the ISM. We assess the solar cycle’s role on the amplitude of ionospheric and solar wind variations. Interstellar refraction can produce cyclic timing variations from the error in transforming arrival times to the solar system barycenter. We apply our methods to DM time series and DM gradient measurements in the literature and assess their consistency with a Kolmogorov medium. Finally, we discuss the implications of DM modeling in precision pulsar timing experiments

Genetic variation in the endocannabinoid system and response to Cognitive Behavior Therapy for child anxiety disorders

Science.gov (United States)

Coleman, Jonathan R. I.; Roberts, Susanna; Keers, Robert; Breen, Gerome; Bögels, Susan; Creswell, Cathy; Hudson, Jennifer L.; McKinnon, Anna; Nauta, Maaike; Rapee, Ronald M.; Schneider, Silvia; Silverman, Wendy K.; Thastum, Mikael; Waite, Polly; Wergeland, Gro Janne H.; Eley, Thalia C.

2016-01-01

Extinction learning is an important mechanism in the successful psychological treatment of anxiety. Individual differences in response and relapse following Cognitive Behavior Therapy may in part be explained by variability in the ease with which fears are extinguished or the vulnerability of these fears to re‐emerge. Given the role of the endocannabinoid system in fear extinction, this study investigates whether genetic variation in the endocannabinoid system explains individual differences in response to CBT. Children (N = 1,309) with a primary anxiety disorder diagnosis were recruited. We investigated the relationship between variation in the CNR1, CNR2, and FAAH genes and change in primary anxiety disorder severity between pre‐ and post‐treatment and during the follow‐up period in the full sample and a subset with fear‐based anxiety disorder diagnoses. Change in symptom severity during active treatment was nominally associated (P < 0.05) with two SNPs. During the follow‐up period, five SNPs were nominally associated with a poorer treatment response (rs806365 [CNR1]; rs2501431 [CNR2]; rs2070956 [CNR2]; rs7769940 [CNR1]; rs2209172 [FAAH]) and one with a more favorable response (rs6928813 [CNR1]). Within the fear‐based subset, the effect of rs806365 survived multiple testing corrections (P < 0.0016). We found very limited evidence for an association between variants in endocannabinoid system genes and treatment response once multiple testing corrections were applied. Larger, more homogenous cohorts are needed to allow the identification of variants of small but statistically significant effect and to estimate effect sizes for these variants with greater precision in order to determine their potential clinical utility. © 2016 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by Wiley Periodicals, Inc. PMID:27346075

Variation for N Uptake System in Maize: Genotypic Response to N Supply

KAUST Repository

Garnett, Trevor; Plett, Darren; Conn, Vanessa; Conn, Simon; Rabie, Huwaida; Rafalski, J. Antoni; Dhugga, Kanwarpal; Tester, Mark A.; Kaiser, Brent N.

2015-01-01

An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO−3) and ammonium (NH+4) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO−3 and NH+4 increased with reduced N. Transcript levels of putative NO−3 and NH+4 transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype's ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals.

Variation for N Uptake System in Maize: Genotypic Response to N Supply

KAUST Repository

Garnett, Trevor

2015-11-09

An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO−3) and ammonium (NH+4) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO−3 and NH+4 increased with reduced N. Transcript levels of putative NO−3 and NH+4 transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype\\'s ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals.

Performance Variation of Spent Resin in Mixed Bed From Water Purifying System of Xi'an Pulse Reactor

International Nuclear Information System (INIS)

Li Hua; Ma Yan; Xiao Yan; Liu Yueheng; Yang Yongqing

2010-01-01

Detailed physical and chemical characteristic analysis was performed on the spent cation and anion resins in the mixed bed from Xi'an Pulse Reactor water purifying system.The exchange performance variations of used resins and the contributions from different factors to the variation were discussed.Based on the obtained information of the impurities in the used resin, the contamination state of the water in the Xi'an Pulse Reactor water pool, the corrosion state of the structural material in the reactor was presented. The spent anion resin almost completely losses its exchange performance,while the remaining exchange capacity in the spent cation resin is still high.The radiation field from the reactor operation contributes little to the degradation of the performance of the resins. The exchange capacity loss of the spent anion resin is due to the exchange of its active groups into abundant carbonate and a certain amount of organics. The impurity amount in the anion and cation exchange resins is low,which suggests(that) the water in the Xi'an Pulse Reactor water pool is little contaminated. A certain extent of corrosion is occurred on the structural material in the swimming pool of the reactor. The results provide important referential data for the operational safety of the water purifying system of similar research reactor. (authors)

Chemical variation in hydrothermal minerals of the Los Humeros geothermal system, Mexico

Energy Technology Data Exchange (ETDEWEB)

Martinez-Serrano, R.G. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico). Insituto de Geofisica

2002-10-01

The Los Humeros geothermal system is composed of more than 2200 m of Quaternary altered volcanic rocks and an underlying Cretaceous sedimentary sequence. The low salinity of the fluids discharged at present (Na{sup +} and Cl{sup -} concentrations <500 ppm), and the excess steam, indicate that the reservoir contains a mixture of steam and dilute groundwater. Water-rock equilibrium is not attained. Hydrothermal minerals are present in veinlets, vugs, and replacing primary minerals. Three mineral zones are recognized: 1) a shallow argillic zone (<400 m depth), 2) a propylitic zone (ranging between 500 and 1800 m) and 3) a skarn zone (>1800 m). Petrographic examination of cuttings from five wells and temperature data indicate at least two stages of hydrothermal activity. Temperature is the main factor that affects the chemical composition of chlorite, epidote and biotite. Fe{sup 2+} and Al{sup IV} increase in chlorite with temperature [from 1.4 formula position unit (fpu) to 2.8, and from 0.7 to 2.4 fpu, respectively]. The pistacite content of epidote varies from 18 to 33 mol% in high-temperature regions (>270 {sup o}C) and from 13 to 26 mol% in low-temperature regions (<250 {sup 0}C). Biotite displays a slight increase in Al{sup IV} contents (1.55-2.8) and octahedral occupancy (5.93-6.0 fpu) with temperature. Whole rock composition and variations in oxygen fugacity condition are factors that also affect the concentrations of Fe, Al and Mg in the octahedral sites of chlorite, epidote, biotite and amphiboles. Chemical variations observed in alteration minerals at different depths in the Colapso Central-Xalapazco region could be used as indicator of relict physico-chemical conditions in the reservoir, before the present economic exploitation. (author)

Major hydrologic shifts in northwest Florida during the Holocene from a lacustrine sediment record

Science.gov (United States)

Rodysill, J. R.; Donnelly, J. P.

2011-12-01

Recent climate extremes have threatened water resource availability and destroyed homes and infrastructure along the heavily populated northern Gulf of Mexico coast. Water resources in Northwest Florida, in particular, suffer from declining aquifer levels and salt water intrusion despite the presence of extensive river and aquifer systems. Intensive water resource management has been necessary to meet water supply demands during recent droughts. Advanced preparedness for abrupt climate events requires the ability to anticipate when hydrologic extremes are likely to occur; however, the long-term history of hydrologic extremes is not well known, and the instrumental record is too short to resolve longer-term hydrologic variability. Reconstructing the pre-instrumental hydrologic history is essential to building our understanding of the timing of and the driving forces behind wet and dry extremes. Here we present a new record of paleohydrology in northwest Florida based upon variations in sediment lithology and geochemistry from Rattlesnake Lake. We see evidence for both brief and long-lived changes in the lake environment during the Holocene. We compare our record to published pollen-based reconstructions of paleohydrology to examine the spatial and temporal patterns of paleohydrologic extremes across the northern Gulf of Mexico region during the Holocene.

VariVis: a visualisation toolkit for variation databases

Directory of Open Access Journals (Sweden)

Smith Timothy D

2008-04-01

Full Text Available Abstract Background With the completion of the Human Genome Project and recent advancements in mutation detection technologies, the volume of data available on genetic variations has risen considerably. These data are stored in online variation databases and provide important clues to the cause of diseases and potential side effects or resistance to drugs. However, the data presentation techniques employed by most of these databases make them difficult to use and understand. Results Here we present a visualisation toolkit that can be employed by online variation databases to generate graphical models of gene sequence with corresponding variations and their consequences. The VariVis software package can run on any web server capable of executing Perl CGI scripts and can interface with numerous Database Management Systems and "flat-file" data files. VariVis produces two easily understandable graphical depictions of any gene sequence and matches these with variant data. While developed with the goal of improving the utility of human variation databases, the VariVis package can be used in any variation database to enhance utilisation of, and access to, critical information.

Calculus of variations

CERN Document Server

Elsgolc, Lev D

2007-01-01

This concise text offers both professionals and students an introduction to the fundamentals and standard methods of the calculus of variations. In addition to surveys of problems with fixed and movable boundaries, it explores highly practical direct methods for the solution of variational problems.Topics include the method of variation in problems with fixed boundaries; variational problems with movable boundaries and other problems; sufficiency conditions for an extremum; variational problems of constrained extrema; and direct methods of solving variational problems. Each chapter features nu

Highly accurate bound state calculations of the two-center molecular ions by using the universal variational expansion for three-body systems

Science.gov (United States)

Frolov, Alexei M.

2018-03-01

The universal variational expansion for the non-relativistic three-body systems is explicitly constructed. This universal expansion can be used to perform highly accurate numerical computations of the bound state spectra in various three-body systems, including Coulomb three-body systems with arbitrary particle masses and electric charges. Our main interest is related to the adiabatic three-body systems which contain one bound electron and two heavy nuclei of hydrogen isotopes: the protium p, deuterium d and tritium t. We also consider the analogous (model) hydrogen ion ∞H2+ with the two infinitely heavy nuclei.

Design, Analysis and Implementation of an Experimental System to Harvest Energy From Atmospheric Temperature Variations Using Ethyl Chloride Filled Bellows

Science.gov (United States)

Ali, Gibran

The increase in global warming and the dwindling supplies of fossil fuels have shifted the focus from traditional to alternate sources of energy. This has resulted in a concerted effort towards finding new energy sources as well as better understanding traditional renewable energy sources such as wind and solar power. In addition to the shift in focus towards alternate energy, the last two decades have offered a dramatic rise in the use of digital technologies such as wireless sensor networks that require small but isolated power supplies. Energy harvesting, a method to gather energy from ambient sources including sunlight, vibrations, heat, etc., has provided some success in powering these systems. One of the unexplored areas of energy harvesting is the use of atmospheric temperature variations to obtain usable energy. This thesis investigates an innovative mechanism to extract energy from atmospheric variations using ethyl chloride filled mechanical bellows. The energy harvesting process was divided into two parts. The first part consisted of extracting energy from the temperature variations and converting it into the potential energy stored in a linear coil spring. This was achieved by designing and fabricating an apparatus that consisted of an ethyl chloride filled bellows working against a mechanical spring in a closed and controlled environment. The bellows expanded/contracted depending upon the ambient temperature and the energy harvested was calculated as a function of the bellows' length. The experiments showed that 6 J of potential energy may be harvested for a 23°C change in temperature. The numerical results closely correlated to the experimental data with an error magnitude of 1%. In regions with high diurnal temperature variation, such an apparatus may yield approximately 250 microwatts depending on the diurnal temperature range. The second part of the energy harvesting process consisted of transforming linear expansion of the bellows into electric

SUBMERGED MACROPHYTE EFFECTS ON NUTRIENT EXCHANGES IN RIVERINE SEDIMENTS

Science.gov (United States)

Submersed macrophytes are important in nutrient cycling in marine and lacustrine systems, although their role in nutrient exchange in tidally-influenced riverine systems is not well studied. In the laboratory, plants significantly lowered porewater nutrient pools of riverine sedi...

Digital immunohistochemistry platform for the staining variation monitoring based on integration of image and statistical analyses with laboratory information system.

Science.gov (United States)

Laurinaviciene, Aida; Plancoulaine, Benoit; Baltrusaityte, Indra; Meskauskas, Raimundas; Besusparis, Justinas; Lesciute-Krilaviciene, Daiva; Raudeliunas, Darius; Iqbal, Yasir; Herlin, Paulette; Laurinavicius, Arvydas

2014-01-01

Digital immunohistochemistry (IHC) is one of the most promising applications brought by new generation image analysis (IA). While conventional IHC staining quality is monitored by semi-quantitative visual evaluation of tissue controls, IA may require more sensitive measurement. We designed an automated system to digitally monitor IHC multi-tissue controls, based on SQL-level integration of laboratory information system with image and statistical analysis tools. Consecutive sections of TMA containing 10 cores of breast cancer tissue were used as tissue controls in routine Ki67 IHC testing. Ventana slide label barcode ID was sent to the LIS to register the serial section sequence. The slides were stained and scanned (Aperio ScanScope XT), IA was performed by the Aperio/Leica Colocalization and Genie Classifier/Nuclear algorithms. SQL-based integration ensured automated statistical analysis of the IA data by the SAS Enterprise Guide project. Factor analysis and plot visualizations were performed to explore slide-to-slide variation of the Ki67 IHC staining results in the control tissue. Slide-to-slide intra-core IHC staining analysis revealed rather significant variation of the variables reflecting the sample size, while Brown and Blue Intensity were relatively stable. To further investigate this variation, the IA results from the 10 cores were aggregated to minimize tissue-related variance. Factor analysis revealed association between the variables reflecting the sample size detected by IA and Blue Intensity. Since the main feature to be extracted from the tissue controls was staining intensity, we further explored the variation of the intensity variables in the individual cores. MeanBrownBlue Intensity ((Brown+Blue)/2) and DiffBrownBlue Intensity (Brown-Blue) were introduced to better contrast the absolute intensity and the colour balance variation in each core; relevant factor scores were extracted. Finally, tissue-related factors of IHC staining variance were

STRATIGRAPHIC EVOLUTION, PALEOENVIRONMENTS AND HYDROCARBON POTENTIALS OF THE BENUE/DAHOMEY BASINS, NIGERIAN AND POTIGUAR/CEARA BASINS, NE BRAZIL

International Nuclear Information System (INIS)

Akande, S.O; Adekeye, O.A.; Oj, O.J; Erdtmann, B.D.; Koutsokous, E.I.

2004-01-01

The stratigraphy, facies relationship and paleoenvironment of selected West African and the Brazillian rift basins permit the recognition of at least two major petroleum systems apart from the prolific Niger Delta petroleum system. The Lower Cretaceous fluivio-lacustrine petroleum system and Upper Cretaceous to Lower Tertiary, marine dominated petroleum system. Our combined studies of the stratigraphic, structural framework, paleoenvironment and time-space relationships of the petroleum systems in the Benue/Dahomey and the Potiguar/Ceara basins indicated that rifting and subsequent drifting during the opening of the South Atlantic controlled subsidence, sediment deposition and facies associations in individual basins. Whereas in the Potiguar/Ceara basins, the best developed source rocks are within the Neomacin-Aptian fluvio- lacustrine sequence of the Pendencia and Alagamar Formations which generated reserved hydrocarbon in the Acu Formation, empirical evidence for this petroleum system in the contiguous Benue/Dahomey basins are only based on the geochemical characteristics of the lower parts of the Bima Formation and the Abeokuta Group. In contrast, the Upper Cretaceous-Lower Tertiary marine petroleum system, which is constrained by poor development of reservoirs in the Potiguar/Ceara basin is productive in the Benue/Dahomey basins where source rocks, reservoir and sealing facies occur at this interval. Considering the recent hydrocarbon discoveries of the East Niger basin, the Doba (southern Chad), the Muglad basin (southern Sudan) sourced from the fluvio-lacustrine rift sequences, we suggest that this petroleum system needs more detailed exploration and has some potentials in the Benue/Dahomey frontier basins

Variation in Broccoli Cultivar Phytochemical Content under Organic and Conventional Management Systems: Implications in Breeding for Nutrition

Science.gov (United States)

Renaud, Erica N. C.; Lammerts van Bueren, Edith T.; Myers, James R.; Paulo, Maria João; van Eeuwijk, Fred A.; Zhu, Ning; Juvik, John A.

2014-01-01

Organic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine). The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (δ-, γ-, α-tocopherol) and carotenoids (lutein, zeaxanthin, β-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For δ- and γ- tocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype (8.41–13.03%) was the largest source of variation and its interactions with location and season. Overall, phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F1 hybrids. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1 hybrids. We identified distinct locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were correlated with one another. Little or no association between

Particle variations and effect on the microstructure and microhardness of Ti6al4V hybrid metal matrix system

CSIR Research Space (South Africa)

Akinlabi, ET

2017-01-01

Full Text Available obtained as follow: 3.0 Ti6Al4 V, B4C and BN, 3.2 Ti6Al4 V, B4C and BN, and 3.4 Ti6Al4 V, B4C and BN systems. Laser coating experiment was done at 1400W. The influence of difference in variation of powder on the microstructure and hardness values...

Variational derivation of a time-dependent Hartree-Fock Hamiltonian

International Nuclear Information System (INIS)

Lichtner, P.C.; Griffin, J.J.; Schultheis, H.; Schultheis, R.; Volkov, A.B.

1979-01-01

The variational derivation of the time-dependent Hartree-Fock equation is reviewed. When norm-violating variations are included, a unique time-dependent Hartree-Fock Hamiltonian, which differs from that customarily used in time-dependent Hartree-Fock analyses, is implied. This variationally ''true'' Hartree-Fock Hamiltonian has the same expectation value as the exact Hamiltonian, equal to the average energy of the system. Since this quantity remains constant under time-dependent Hartree-Fock time evolution, we suggest the label ''constant '' for this form of time-dependent Hartree-Fock theory

Phase rainbow refractometry for accurate droplet variation characterization.

Science.gov (United States)

Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

2016-10-15

We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

Climatic changes and anthropogenic pollution as evidenced by two Alpine lacustrine records, Switzerland.

Science.gov (United States)

Thevenon, Florian; Poté, John; Guédron, Stéphane; Adatte, Thierry; Chiaradia, Massimo; Loizeau, Jean-Luc; Spangenberg, Jorge; Anselmetti, Flavio S.

2010-05-01

This study aims to provide high-resolution records of climatic changes and human impacts on two different Alpine environments: Lake Lucerne is a large (114 km2) lake located at 434 m asl in Central Switzerland, whereas Meidsee is a small (industrial history and the last millennia were sampled with a resolution of 1 cm, and investigated for organic (13δC, 15δN, C/N) and/or inorganic (δ13C, δ18O) matter contents, and elemental composition (REE compositions, trace elements, and heavy metals). Both sites exhibit 1) rapid hydrological changes related to variations in winter precipitations, and 2) increases in atmospheric pollution due to human activities. Lead enrichment factors combined to changes in lead isotopic composition (206Pb/207Pb ratio) are used to distinguish natural from anthropogenic sources. The greatest mercury and lead atmospheric emissions occurred during the twentieth century, resulting from the extensive combustion of fossil coal and petroleum in Europe. Although the highest heavy metals fluxes are synchronous with major anthropogenic changes (e.g. Roman mining, industrial revolution), proxies show that in absence of such events, the heavy metals deposition in the sedimentary records is primarily influenced by sedimentological processes linked to climate variations (i.e. runoff and erosion processes).

Temporal and spatial variations in fly ash quality

Science.gov (United States)

Hower, J.C.; Trimble, A.S.; Eble, C.F.

2001-01-01

Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

Systems genetics analysis of pharmacogenomics variation during antidepressant treatment

DEFF Research Database (Denmark)

Madsen, Majbritt Busk; Kogelman, L J A; Kadarmideen, H N

2016-01-01

Selective serotonin reuptake inhibitors (SSRIs) are the most widely used antidepressants, but the efficacy of the treatment varies significantly among individuals. It is believed that complex genetic mechanisms play a part in this variation. We have used a network based approach to unravel the in...... genes involved in calcium homeostasis. In conclusion, we suggest a difference in genetic interaction networks between initial and subsequent SSRI response.The Pharmacogenomics Journal advance online publication, 18 October 2016; doi:10.1038/tpj.2016.68....

Linking groundwater dissolved organic matter to sedimentary organic matter from a fluvio-lacustrine aquifer at Jianghan Plain, China by EEM-PARAFAC and hydrochemical analyses.

Science.gov (United States)

Huang, Shuang-bing; Wang, Yan-xin; Ma, Teng; Tong, Lei; Wang, Yan-yan; Liu, Chang-rong; Zhao, Long

2015-10-01

The sources of dissolved organic matter (DOM) in groundwater are important to groundwater chemistry and quality. This study examined similarities in the nature of DOM and investigated the link between groundwater DOM (GDOM) and sedimentary organic matter (SOM) from a lacustrine-alluvial aquifer at Jianghan Plain. Sediment, groundwater and surface water samples were employed for SOM extraction, optical and/or chemical characterization, and subsequent fluorescence excitation-emission matrix (EEM) and parallel factor analyses (PARAFAC). Spectroscopic properties of bulk DOM pools showed that indices indicative of GDOM (e.g., biological source properties, humification level, aromaticity and molecule mobility) varied within the ranges of those of two extracted end-members of SOM: humic-like materials and microbe-associated materials. The coexistence of PARAFAC compositions and the sustaining internal relationship between GDOM and extracted SOM indicate a similar source. The results from principal component analyses with selected spectroscopic indices showed that GDOM exhibited a transition trend regarding its nature: from refractory high-humification DOM to intermediate humification DOM and then to microbe-associated DOM, with decreasing molecular weight. Correlations of spectroscopic indices with physicochemical parameters of the groundwater suggested that GDOM was released from SOM and was modified by microbial diagenetic processes. The current study demonstrated the associations of GDOM with SOM from a spectroscopic viewpoint and provided new evidence supporting SOM as the source of GDOM. Copyright © 2015 Elsevier B.V. All rights reserved.

Examining Water Quality Variations of Tidal Pond System

Science.gov (United States)

Chui, T. F. M.; Cui, W.

2014-12-01

Brackish tidal shrimp ponds, traditionally referred to as gei wais, have been constructed along coastal areas in many parts of the world. The regular exchange of pond water with the surrounding coastal environment is important as it brings shrimp larvae and nutrients, etc. into and out of the pond. Such a water exchange can reduce the quality of the receiving waters; though there are opposing views recently because farming practices are becoming more sustainable while other sources of pollutions in the surroundings are increasing. This project monitors the water quality of a tidal shrimp pond and its receiving water at high temporal resolution. The pond is located within the wetland complex of Mai Po Nature Reserve in Hong Kong, China. Water quality parameters (i.e., dissolved oxygen, temperature, salinity, pH, water depth and chlorophyll) were recorded at 15-minute interval from December 2013 to March 2014 within the pond and also at its receiving water which is a water channel within a mangrove forest. Data reveals both daily and fortnightly fluctuations. Daily variations in mangrove correspond to both tidal flushing and insolation, whereas those within the pond correspond mainly to insolation. For example, dissolved oxygen in mangrove shows two peaks daily which correlate with tidal elevation, and that within the pond shows only one peak which correlates with sunlight. Dissolved oxygen within the pond also shows a fortnightly pattern that corresponds to the schedule of water exchange. Such high temporal resolution of monitoring reveals the two-way water quality influences between the pond and the mangrove. It sheds insights that can possibly lead to refinement of water exchange practice and water sampling schedule given the temporal variations of the water quality both inside and outside the pond. It thus enables us to take a step closer in adopting more sustainable farming practices despite increasing pollution in the surrounding areas.

Inclusion of ecologically based trait variation in plant functional types reduces the projected land carbon sink in an earth system model.

Science.gov (United States)

Verheijen, Lieneke M; Aerts, Rien; Brovkin, Victor; Cavender-Bares, Jeannine; Cornelissen, Johannes H C; Kattge, Jens; van Bodegom, Peter M

2015-08-01

Earth system models demonstrate large uncertainty in projected changes in terrestrial carbon budgets. The lack of inclusion of adaptive responses of vegetation communities to the environment has been suggested to hamper the ability of modeled vegetation to adequately respond to environmental change. In this study, variation in functional responses of vegetation has been added to an earth system model (ESM) based on ecological principles. The restriction of viable mean trait values of vegetation communities by the environment, called 'habitat filtering', is an important ecological assembly rule and allows for determination of global scale trait-environment relationships. These relationships were applied to model trait variation for different plant functional types (PFTs). For three leaf traits (specific leaf area, maximum carboxylation rate at 25 °C, and maximum electron transport rate at 25 °C), relationships with multiple environmental drivers, such as precipitation, temperature, radiation, and CO2 , were determined for the PFTs within the Max Planck Institute ESM. With these relationships, spatiotemporal variation in these formerly fixed traits in PFTs was modeled in global change projections (IPCC RCP8.5 scenario). Inclusion of this environment-driven trait variation resulted in a strong reduction of the global carbon sink by at least 33% (2.1 Pg C yr(-1) ) from the 2nd quarter of the 21st century onward compared to the default model with fixed traits. In addition, the mid- and high latitudes became a stronger carbon sink and the tropics a stronger carbon source, caused by trait-induced differences in productivity and relative respirational costs. These results point toward a reduction of the global carbon sink when including a more realistic representation of functional vegetation responses, implying more carbon will stay airborne, which could fuel further climate change. © 2015 John Wiley & Sons Ltd.

Variation in the ovine cortisol response to systemic bacterial endotoxin challenge is predominantly determined by signalling within the hypothalamic-pituitary-adrenal axis

International Nuclear Information System (INIS)

You Qiumei; Karrow, Niel A.; Cao Honghe; Rodriguez, Alexander; Mallard, Bonnie A.; Boermans, Herman J.

2008-01-01

Bi-directional communication between the neuroendocrine and immune systems is designed, in part, to maintain or restore homeostasis during physiological stress. Exposure to endotoxin during Gram-negative bacterial infection for example, elicits the release of pro-inflammatory cytokines that activate the hypothalamic-pituitary-adrenal axis (HPAA). The secretion of adrenal glucocorticoids subsequently down regulates the host inflammatory response, minimizing potential tissue damage. Sequence and epigenetic variants in genes involved in regulating the neuroendocrine and immune systems are likely to contribute to individual differences in the HPAA response, and this may influence the host anti-inflammatory response to toxin exposure and susceptibility to inflammatory disease. In this study, high (HCR) and low (LCR) cortisol responders were selected from a normal population of 110 female sheep challenged iv with Escherichia coli endotoxin (400 ng/kg) to identify potential determinants that contribute to variation in the cortisol response phenotype. This phenotype was stable over several years in the HCR and LCR animals, and did not appear to be attributed to differences in expression of hepatic immune-related genes or systemic pro-inflammatory cytokine concentrations. Mechanistic studies using corticotrophin-releasing factor (0.5 μg/kg body weight), arginine vasopressin (0.5 μg/kg), and adrenocorticotropic hormone (0.5 μg/kg) administered iv demonstrated that variation in this phenotype is largely determined by signalling within the HPAA. Future studies will use this ovine HCR/LCR model to investigate potential genetic and epigenetic variants that may contribute to variation in cortisol responsiveness to bacterial endotoxin

A New Result Concerning the Solvability of a Class of General Systems of Variational Equations with Nonmonotone Operators: Applications to Dirichlet and Neumann Nonlinear Problems

Directory of Open Access Journals (Sweden)

Luisa Toscano

2016-01-01

Full Text Available A new result of solvability for a wide class of systems of variational equations depending on parameters and governed by nonmonotone operators is found in a Banach real and reflexive space with applications to Dirichlet and Neumann problems related to nonlinear elliptic systems.

Calculations of wavefunctions and energies of electron system in Coulomb potential by variational method without a basis set

International Nuclear Information System (INIS)

Bykov, V.P.; Gerasimov, A.V.

1992-08-01

A new variational method without a basis set for calculation of the eigenvalues and eigenfunctions of Hamiltonians is suggested. The expansion of this method for the Coulomb potentials is given. Calculation of the energy and charge distribution in the two-electron system for different values of the nuclear charge Z is made. It is shown that at small Z the Coulomb forces disintegrate the electron cloud into two clots. (author). 3 refs, 4 figs, 1 tab

Damping Effect of an Unsaturated-Saturated System on Tempospatial Variations of Pressure Head and Specific Flux

Science.gov (United States)

Yang, C.; Zhang, Y. K.; Liang, X.

2014-12-01

Damping effect of an unsaturated-saturated system on tempospatialvariations of pressurehead and specificflux was investigated. The variance and covariance of both pressure head and specific flux in such a system due to a white noise infiltration were obtained by solving the moment equations of water flow in the system and verified with Monte Carlo simulations. It was found that both the pressure head and specific flux in this case are temporally non-stationary. The variance is zero at early time due to a deterministic initial condition used, then increases with time, and approaches anasymptotic limit at late time.Both pressure head and specific flux arealso non-stationary in space since the variance decreases from source to sink. The unsaturated-saturated systembehavesasa noise filterand it damps both the pressure head and specific flux, i.e., reduces their variations and enhances their correlation. The effect is stronger in upper unsaturated zone than in lower unsaturated zone and saturated zone. As a noise filter, the unsaturated-saturated system is mainly a low pass filter, filtering out the high frequency components in the time series of hydrological variables. The damping effect is much stronger in the saturated zone than in the saturated zone.

Managing Cultural Variation in Software Process Improvement

DEFF Research Database (Denmark)

Kræmmergaard, Pernille; Müller, Sune Dueholm; Mathiassen, Lars

The scale and complexity of change in software process improvement (SPI) are considerable and managerial attention to organizational culture during SPI can therefore potentially contribute to successful outcomes. However, we know little about the impact of variations in organizational subculture...... on SPI initiatives. On this backdrop, we report from a large scale SPI project in a Danish high-tech company, Terma. Two of its business units - Integrated Systems (ISY) and Airborne Systems (ASY) - followed similar approaches over a two year period, but with quite different outcomes. While ISY reached...... CMMI level 2 as planned, ASY struggled to implement even modest improvements. To explain these differences, we analyzed the underlying organizational culture within ISY and ASY using two different methods for subculture assessment. The study demonstrates how variations in culture across software...

Degenerate variational integrators for magnetic field line flow and guiding center trajectories

Science.gov (United States)

Ellison, C. L.; Finn, J. M.; Burby, J. W.; Kraus, M.; Qin, H.; Tang, W. M.

2018-05-01

Symplectic integrators offer many benefits for numerically approximating solutions to Hamiltonian differential equations, including bounded energy error and the preservation of invariant sets. Two important Hamiltonian systems encountered in plasma physics—the flow of magnetic field lines and the guiding center motion of magnetized charged particles—resist symplectic integration by conventional means because the dynamics are most naturally formulated in non-canonical coordinates. New algorithms were recently developed using the variational integration formalism; however, those integrators were found to admit parasitic mode instabilities due to their multistep character. This work eliminates the multistep character, and therefore the parasitic mode instabilities via an adaptation of the variational integration formalism that we deem "degenerate variational integration." Both the magnetic field line and guiding center Lagrangians are degenerate in the sense that the resultant Euler-Lagrange equations are systems of first-order ordinary differential equations. We show that retaining the same degree of degeneracy when constructing discrete Lagrangians yields one-step variational integrators preserving a non-canonical symplectic structure. Numerical examples demonstrate the benefits of the new algorithms, including superior stability relative to the existing variational integrators for these systems and superior qualitative behavior relative to non-conservative algorithms.

First-order system least squares and the energetic variational approach for two-phase flow

Science.gov (United States)

Adler, J. H.; Brannick, J.; Liu, C.; Manteuffel, T.; Zikatanov, L.

2011-07-01

This paper develops a first-order system least-squares (FOSLS) formulation for equations of two-phase flow. The main goal is to show that this discretization, along with numerical techniques such as nested iteration, algebraic multigrid, and adaptive local refinement, can be used to solve these types of complex fluid flow problems. In addition, from an energetic variational approach, it can be shown that an important quantity to preserve in a given simulation is the energy law. We discuss the energy law and inherent structure for two-phase flow using the Allen-Cahn interface model and indicate how it is related to other complex fluid models, such as magnetohydrodynamics. Finally, we show that, using the FOSLS framework, one can still satisfy the appropriate energy law globally while using well-known numerical techniques.

Variation in thickness of the large cryosections cut for whole-body autoradiography

International Nuclear Information System (INIS)

Ito, Tsunao; Brill, A.B.

1991-01-01

A method to assess variation in thickness of the large cryosections for whole-body autoradiography (WBARG) was described, and the degree of intraslice and interslice variations were determined for our cryomicrotome system (LKB PMV-2250). Intraslice variation in thickness of the 180 x 80 mm cryosection was 0.72-0.92 μm within the range of section thickness for WBARG (15-50 μm), and interslice variation was 0.89-1.21 μm. These potential variations in section thickness should be kept in mind whenever working with quantitative WBARG. (author)

Variational characterization of generalized Jacobi equations

International Nuclear Information System (INIS)

Casciaro, B.

1995-09-01

A Lagrangian depending on derivatives of the fields up to a generic order is considered, together with a series development around a given section. The problem of extremality and stability of action for this system is then addressed. Higher-order variations in the Lagrangian, the Euler-Lagrange equation, the expansion of the action, the D-invariant decomposition of the Lagrangian, the Jacobi equation, and a unified description of the Euler-Lag range and Jacobi equations are discussed. As a conclusion of the work it is stated that the theory of second variations is worthy to be revisited and a comment on a recent paper by Taub is made. 10 refs

Is there much variation in variation? Revisiting statistics of small area variation in health services research

Directory of Open Access Journals (Sweden)

Ibáñez Berta

2009-04-01

Full Text Available Abstract Background The importance of Small Area Variation Analysis for policy-making contrasts with the scarcity of work on the validity of the statistics used in these studies. Our study aims at 1 determining whether variation in utilization rates between health areas is higher than would be expected by chance, 2 estimating the statistical power of the variation statistics; and 3 evaluating the ability of different statistics to compare the variability among different procedures regardless of their rates. Methods Parametric bootstrap techniques were used to derive the empirical distribution for each statistic under the hypothesis of homogeneity across areas. Non-parametric procedures were used to analyze the empirical distribution for the observed statistics and compare the results in six situations (low/medium/high utilization rates and low/high variability. A small scale simulation study was conducted to assess the capacity of each statistic to discriminate between different scenarios with different degrees of variation. Results Bootstrap techniques proved to be good at quantifying the difference between the null hypothesis and the variation observed in each situation, and to construct reliable tests and confidence intervals for each of the variation statistics analyzed. Although the good performance of Systematic Component of Variation (SCV, Empirical Bayes (EB statistic shows better behaviour under the null hypothesis, it is able to detect variability if present, it is not influenced by the procedure rate and it is best able to discriminate between different degrees of heterogeneity. Conclusion The EB statistics seems to be a good alternative to more conventional statistics used in small-area variation analysis in health service research because of its robustness.

Genetic Variations and their Association with Diseases among ...

African Journals Online (AJOL)

genetics plays in disease, death and infections. The mode of study involved a combination of a retrospective study and the analysis of genetic variation among Kenyan ethnic populations using ABO blood group system. The results showed that there was association between allele frequencies of ABO system and disease ...

Hybrid Steepest-Descent Methods for Triple Hierarchical Variational Inequalities

Directory of Open Access Journals (Sweden)

L. C. Ceng

2015-01-01

Full Text Available We introduce and analyze a relaxed iterative algorithm by combining Korpelevich’s extragradient method, hybrid steepest-descent method, and Mann’s iteration method. We prove that, under appropriate assumptions, the proposed algorithm converges strongly to a common element of the fixed point set of infinitely many nonexpansive mappings, the solution set of finitely many generalized mixed equilibrium problems (GMEPs, the solution set of finitely many variational inclusions, and the solution set of general system of variational inequalities (GSVI, which is just a unique solution of a triple hierarchical variational inequality (THVI in a real Hilbert space. In addition, we also consider the application of the proposed algorithm for solving a hierarchical variational inequality problem with constraints of finitely many GMEPs, finitely many variational inclusions, and the GSVI. The results obtained in this paper improve and extend the corresponding results announced by many others.

Patient-reported outcomes in adults with congenital heart disease: Inter-country variation, standard of living and healthcare system factors.

Science.gov (United States)

Moons, Philip; Kovacs, Adrienne H; Luyckx, Koen; Thomet, Corina; Budts, Werner; Enomoto, Junko; Sluman, Maayke A; Yang, Hsiao-Ling; Jackson, Jamie L; Khairy, Paul; Cook, Stephen C; Subramanyan, Raghavan; Alday, Luis; Eriksen, Katrine; Dellborg, Mikael; Berghammer, Malin; Johansson, Bengt; Mackie, Andrew S; Menahem, Samuel; Caruana, Maryanne; Veldtman, Gruschen; Soufi, Alexandra; Fernandes, Susan M; White, Kamila; Callus, Edward; Kutty, Shelby; Van Bulck, Liesbet; Apers, Silke

2018-01-15

Geographical differences in patient-reported outcomes (PROs) of adults with congenital heart disease (ConHD) have been observed, but are poorly understood. We aimed to: (1) investigate inter-country variation in PROs in adults with ConHD; (2) identify patient-related predictors of PROs; and (3) explore standard of living and healthcare system characteristics as predictors of PROs. Assessment of Patterns of Patient-Reported Outcomes in Adults with Congenital Heart disease - International Study (APPROACH-IS) was a cross-sectional, observational study, in which 4028 patients from 15 countries in 5 continents were enrolled. Self-report questionnaires were administered: patient-reported health (12-item Short Form Health Survey; EuroQOL-5D Visual Analog Scale); psychological functioning (Hospital Anxiety and Depression Scale); health behaviors (Health Behavior Scale-Congenital Heart Disease) and quality of life (Linear Analog Scale for quality of life; Satisfaction With Life Scale). A composite PRO score was calculated. Standard of living was expressed as Gross Domestic Product per capita and Human Development Index. Healthcare systems were operationalized as the total health expenditure per capita and the overall health system performance. Substantial inter-country variation in PROs was observed, with Switzerland having the highest composite PRO score (81.0) and India the lowest (71.3). Functional class, age, and unemployment status were patient-related factors that independently and consistently predicted PROs. Standard of living and healthcare system characteristics predicted PROs above and beyond patient characteristics. This international collaboration allowed us to determine that PROs in ConHD vary as a function of patient-related factors as well as the countries in which patients live. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of Fault-Controlled Topography on Fluvio-Deltaic Sedimentary Systems in Eberswalde Crater, Mars

Science.gov (United States)

Rice, Melissa S.; Gupta, Sanjeev; Bell, James F., III; Warner, Nicholas H.

2011-01-01

Eberswalde crater was selected as a candidate landing site for the Mars Science Laboratory (MSL) mission based on the presence of a fan-shaped sedimentary deposit interpreted as a delta. We have identified and mapped five other candidate fluvio -deltaic systems in the crater, using images and digital terrain models (DTMs) derived from the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX). All of these systems consist of the same three stratigraphic units: (1) an upper layered unit, conformable with (2) a subpolygonally fractured unit, unconformably overlying (3) a pitted unit. We have also mapped a system of NNE-trending scarps interpreted as dip-slip faults that pre-date the fluvial -lacustrine deposits. The post-impact regional faulting may have generated the large-scale topography within the crater, which consists of a Western Basin, an Eastern Basin, and a central high. This topography subsequently provided depositional sinks for sediment entering the crater and controlled the geomorphic pattern of delta development.

Copper smelting and sediment pollution in Bronze Age China.

Science.gov (United States)

Zhang, S.; Dong, G.

2017-12-01

The emergence and diffusion of metallurgical technology had tremendous environmental consequence, however, the spatial-temporal consequences of the metallurgy during Bronze Age are not clear in China. Here, Xray fluorescence (XRF) measurement and principal component analysis (PCA) were conducted on heavy metal element (Cu, Ni, Pb, Zn, Cr and As) concentrations (HMEC) of natural and anthropogenic sediment samples systematically collected from 22 late Neolithic-Bronze Age sites in Hexi corridor to explore the potential for subcontinental-wide changes in soil geochemistry. We place this data within the context of the Cu concentrations in lacustrine sediments located near smelting and mining centers in Bronze Age China. Our results show that variation of HMEC in anthropogenic sediment in Hexi corridor is contemporaneous with the increases of the Cu concentrations in lacustrine sediment around 4000 BP. Comparative data suggests the metallurgical production diffused from the Hexi corridor to central and southwestern China around 3600 BP. We argue that sediment pollution is not an isolated phenomenon during the Bronze Age China, but rather occurred on regional scales and is closely related to the intensity of smelting activities.

Variationally Optimized Free-Energy Flooding for Rate Calculation

Science.gov (United States)

McCarty, James; Valsson, Omar; Tiwary, Pratyush; Parrinello, Michele

2015-08-01

We propose a new method to obtain kinetic properties of infrequent events from molecular dynamics simulation. The procedure employs a recently introduced variational approach [Valsson and Parrinello, Phys. Rev. Lett. 113, 090601 (2014)] to construct a bias potential as a function of several collective variables that is designed to flood the associated free energy surface up to a predefined level. The resulting bias potential effectively accelerates transitions between metastable free energy minima while ensuring bias-free transition states, thus allowing accurate kinetic rates to be obtained. We test the method on a few illustrative systems for which we obtain an order of magnitude improvement in efficiency relative to previous approaches and several orders of magnitude relative to unbiased molecular dynamics. We expect an even larger improvement in more complex systems. This and the ability of the variational approach to deal efficiently with a large number of collective variables will greatly enhance the scope of these calculations. This work is a vindication of the potential that the variational principle has if applied in innovative ways.

Variation simulation for compliant sheet metal assemblies with applications

Science.gov (United States)

Long, Yufeng

Sheet metals are widely used in discrete products, such as automobiles, aircraft, furniture and electronics appliances, due to their good manufacturability and low cost. A typical automotive body assembly consists of more than 300 parts welded together in more than 200 assembly fixture stations. Such an assembly system is usually quite complex, and takes a long time to develop. As the automotive customer demands products of increasing quality in a shorter time, engineers in automotive industry turn to computer-aided engineering (CAE) tools for help. Computers are an invaluable resource for engineers, not only to simplify and automate the design process, but also to share design specifications with manufacturing groups so that production systems can be tooled up quickly and efficiently. Therefore, it is beneficial to develop computerized simulation and evaluation tools for development of automotive body assembly systems. It is a well-known fact that assembly architectures (joints, fixtures, and assembly lines) have a profound impact on dimensional quality of compliant sheet metal assemblies. To evaluate sheet metal assembly architectures, a special dimensional analysis tool need be developed for predicting dimensional variation of the assembly. Then, the corresponding systematic tools can be established to help engineers select the assembly architectures. In this dissertation, a unified variation model is developed to predict variation in compliant sheet metal assemblies by considering fixture-induced rigid-body motion, deformation and springback. Based on the unified variation model, variation propagation models in multiple assembly stations with various configurations are established. To evaluate the dimensional capability of assembly architectures, quantitative indices are proposed based on the sensitivity matrix, which are independent of the variation level of the process. Examples are given to demonstrate their applications in selecting robust assembly

Keeping Nerves: Central Nervous System of the Interstitial Acochlidiid Parhedyle cryptophthalma (Gastropoda, Opisthobranchia)

DEFF Research Database (Denmark)

Joerger, Katharina; Kristof, Alen; Klussmann-Kolb, Annette

2008-01-01

Unusually well-preserved fossils of a Halicyne-like cycloid crustacean frequently occur in the early Late Triassic lacustrine clay bed at Krasiejów in Opole Silesia, southern Poland. Its gill-like structures form a horseshoe-shaped pair of units composed of numerous calcified blades with reverse ...

Sliding-Mode Control to Compensate PVT Variations in Dual Core Systems

NARCIS (Netherlands)

Pourshaghaghi, H.R.; Fatemi, S.H.; Pineda de Gyvez, J.

2012-01-01

In this paper, we present a novel robust sliding-mode controller for stabilizing supply voltage and clock frequency of dual core processors determined by dynamic voltage and frequency scaling (DVFS) methods in the presence of systematic and random variations. We show that maximum rejection for

Physiological mechanisms of imprinting and homing migration in Pacific salmon Oncorhynchus spp.

Science.gov (United States)

Ueda, H

2012-07-01

After several years of feeding at sea, salmonids have an amazing ability to migrate long distances from the open ocean to their natal stream to spawn. Three different research approaches from behavioural to molecular biological studies have been used to elucidate the physiological mechanisms underpinning salmonid imprinting and homing migration. The study was based on four anadromous Pacific salmon Oncorhynchus spp., pink salmon Oncorhynchus gorbuscha, chum salmon Oncorhynchus keta, sockeye salmon Oncorhynchus nerka and masu salmon Oncorhynchus masou, migrating from the North Pacific Ocean to the coast of Hokkaido, Japan, as well as lacustrine O. nerka and O. masou in Lake Toya, Hokkaido, where the lake serves as the model oceanic system. Behavioural studies using biotelemetry techniques showed swimming profiles from the Bering Sea to the coast of Hokkaido in O. keta as well as homing behaviours of lacustrine O. nerka and O. masou in Lake Toya. Endocrinological studies on hormone profiles in the brain-pituitary-gonad axis of O. keta, and lacustrine O. nerka identified the hormonal changes during homing migration. Neurophysiological studies revealed crucial roles of olfactory functions on imprinting and homing during downstream and upstream migration, respectively. These findings are discussed in relation to the physiological mechanisms of imprinting and homing migration in anadromous and lacustrine salmonids. © 2012 The Author. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

A predictive model for the behavior of radionuclides in lake systems

International Nuclear Information System (INIS)

Monte, L.

1993-01-01

This paper describes a predictive model for the behavior of 137Cs in lacustrine systems. The model was tested by comparing its predictions to contamination data collected in various lakes in Europe and North America. The migration of 137Cs from catchment basin and from bottom sediments to lake water was discussed in detail; these two factors influence the time behavior of contamination in lake water. The contributions to the levels of radionuclide concentrations in water, due to the above factors, generally increase in the long run. The uncertainty of the model, used as a generic tool for prediction of the levels of contamination in lake water, was evaluated. Data sets of water contamination analyzed in the present work suggest that the model uncertainty, at a 68% confidence level, is a factor 1.9

Presymplectic current and the inverse problem of the calculus of variations

Science.gov (United States)

Khavkine, Igor

2013-11-01

The inverse problem of the calculus of variations asks whether a given system of partial differential equations (PDEs) admits a variational formulation. We show that the existence of a presymplectic form in the variational bicomplex, when horizontally closed on solutions, allows us to construct a variational formulation for a subsystem of the given PDE. No constraints on the differential order or number of dependent or independent variables are assumed. The proof follows a recent observation of Bridges, Hydon, and Lawson [Math. Proc. Cambridge Philos. Soc. 148(01), 159-178 (2010)] and generalizes an older result of Henneaux [Ann. Phys. 140(1), 45-64 (1982)] from ordinary differential equations (ODEs) to PDEs. Uniqueness of the variational formulation is also discussed.

The use of the alluvial-lacustrine aquifer like a regulation reservoir. The example of the Oricola (Abruzzo); L'uso di acquiferi fluvio-lacustri quali serbatoi naturali di compenso. L'esempio della piana di Oricola (Abruzzo)

Energy Technology Data Exchange (ETDEWEB)

Celico, F. [Isernia Univ. degli Studi del Molise, Isernia (Italy). Dipt. di Scienze e Tecnologie per l' Ambiente e il Territorio; Habetswallner, F. [Naples Univ. Federico 2., Naples (Italy). Dipt. di Geofisica e Vulcanologia

2000-12-01

The hypothesis of using the Oricola Plane's alluvial-lacustrine aquifer (Abruzzo) like a regulation reservoir has been studied. The alluvial-lacustrine aquifer is constituted by silty and sandy deposits. The idea of using the aquifer like a regulation reservoir has been developed after the realization of a geophysical survey. Twenty six V.E.S. has been realised, with an AB distance of 300-400 metres. The volume of the reservoir, that is to say the volume of sand and gravel in the saturated medium, is about 3,8 x 10{sup 6} m{sup 3}. The results of this survey has been interpreted as a function of the drilling results near l'Immagine area. During the first test an effective porosity of 9,25% has been calculated for the medium-high portion of the reservoir. The results of a mathematical and physical model show that a mathematical transient model of groundwater flow can be implemented. [Italian] Lo studio condotto ha consentito di formulare un'ipotesi di utilizzo dell'aquifero fluvio-lacustre della piana di Oricola (Abruzzo) quale serbatoio naturale di compenso. E' stata infatti individuata una configurazione a catino della porzione centro-occidentale dell'aquifero, il cui volume e' pari a circa 3,8 x 10{sup 6} m{sup 3}. La determinazione sperimentale della porosita' efficace dei depositi fluvio-lacustri, oscillante tra il 4% ed il 9,5% circa, ha consentito a sua volta di calcolare il volume idrico invasato al di sotto del livello piezometrico di piena (pari a circa 0,28 x 10{sup 6} m{sup 3}), nonche' la sua variazione al progressivo decremento del livello di falda, prevalentemente indotto dagli emungimenti. Allo scopo di consentire una programmazione consapevole degli scenari di utilizzazione del serbatoio di compenso nel breve periodo, sono state messe a punto delle equazioni di correlazione tra le riserve permanenti presenti nel serbatoio stesso e la profondita' della falda dal piano campagna. Tutto quanto finora

The variational method in the atomic structure calcularion

International Nuclear Information System (INIS)

Tomimura, A.

1970-01-01

The importance and limitations of variational methods on the atomic structure calculations is set into relevance. Comparisons are made to the Perturbation Theory. Ilustrating it, the method is applied to the H - , H + and H + 2 simple atomic structure systems, and the results are analysed with basis on the study of the associated essential eigenvalue spectrum. Hydrogenic functions (where the screening constants are replaced by variational parameters) are combined to construct the wave function with proper symmetry for each one of the systems. This shows the existence of a bound state for H - , but no conclusions can be made for the others, where it may or may not be necessary to use more flexible wave functions, i.e., with greater number of terms and parameters. (author) [pt

Temperature fluctuations underneath the ice in Diamond Lake, Hennepin County, Minnesota

Czech Academy of Sciences Publication Activity Database

Kletetschka, Günther; Fischer, T.; Mls, J.; Dědeček, Petr

2013-01-01

Roč. 49, č. 6 (2013), s. 3306-3313 ISSN 0043-1397 R&D Projects: GA AV ČR IAA300120905 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z30120515 Institutional support: RVO:67985831 ; RVO:67985530 Keywords : baroclinic seiches * ground water * Lacustrine ice * Lacustrine temperature * Lacustrine water * tides Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.709, year: 2013

Numerical Simulation of the Variation of Schumann Resonance Associated with Seismogenic Processe in the Lithosphere-Atmosphere-Ionosphere system

Science.gov (United States)

Liu, L.; Huang, Q.; Wang, Y.

2012-12-01

The variations in the strength and frequency shift of the Schumann resonance (SR) of the electromagnetic (EM) field prior to some significance earthquakes were reported by a number of researchers. As a robust physical phenomenon constantly exists in the resonant cavity formed by the lithosphere-atmosphere-ionosphere system, irregular variations in SR parameters can be naturally attributed to be the potential precursory observables for forecasting earthquake occurrences. Schumann resonance (SR) of the EM field between the lithosphere and the ionosphere occurs because the space between the surface of the Earth and the conductive ionosphere acts as a closed waveguide. The cavity is naturally excited by electric currents generated by lightning. SR is the principal background in the electromagnetic spectrum at extremely low frequencies (ELF) between 3-69 Hz. We simulated the EM field in the lithosphere-ionosphere waveguide with a 2-dimensional (2D), cylindrical whole-earth model by the hybrid pseudo-spectral and finite difference time domain method. Considering the seismogensis as a fully coupled seismoelectric process, we simulate the seismic wave and EM wave in this 2D model. The excitation of SR in the background EM field are generated by the electric-current impulses due to lightning thunderstorms within the lowest 10 kilometers of the atmosphere . The diurnal variation and the latitude-dependence in ion concentration in the ionosphere are included in the model. After the SR has reached the steady state, the impulse generated by the seismogenic process (pre-, co- and post-seismic) in the crust is introduced to assess the possible precursory effects on SR strength and frequency. The modeling results explain the observed fact of why SR has a much more sensitive response to continental earthquakes, and much less response to oceanic events; the reason is simply due to the shielding effect of the conductive ocean that prevents effective radiation of the seismoelectric

Inverse Problem and Variation Method to Optimize Cascade Heat Exchange Network in Central Heating System

Institute of Scientific and Technical Information of China (English)

ZHANG Yin; WEI Zhiyuan; ZHANG Yinping; WANG Xin

2017-01-01

Urban heating in northern China accounts for 40％ of total building energy usage.In central heating systems,heat is often transfened from heat source to users by the heat network where several heat exchangers arc installed at heat source,substations and terminals respectively.For given overall heating capacity and heat source temperarure,increasing the terminal fluid temperature is an effective way to improve the thermal performance of such cascade heat exchange network for energy saving.In this paper,the mathematical optimization model of the cascade heat exchange network with three-stage heat exchangers in series is established.Aim at maximizing the cold fluid temperature for given hot fluid temperature and overall heating capacity,the optimal heat exchange area distribution and the medium fluids' flow rates are determined through inverse problem and variation method.The preliminary results show that the heat exchange areas should be distributed equally for each heat exchanger.It also indicates that in order to improve the thernmal performance of the whole system,more heat exchange areas should be allocated to the heat exchanger where flow rate difference between two fluids is relatively small.This work is important for guiding the optimization design of practical cascade heating systems.

Coordinated frequency control from offshore wind power plants connected to multi terminal DC system considering wind speed variation

DEFF Research Database (Denmark)

Sakamuri, Jayachandra N.; Altin, Müfit; Hansen, Anca Daniela

2017-01-01

A coordinated fast primary frequency control scheme from offshore wind power plants (OWPPs) integrated to a three terminal high voltage DC (HVDC) system is proposed in this study. The impact of wind speed variation on the OWPP active power output and thus on the AC grid frequency and DC grid...... the active power support from OWPP with a ramp rate limiter and (iii) An alternative method for the wind turbine overloading considering rotor speed. The effectiveness of the proposed control scheme is demonstrated on a wind power plant integrated into a three terminal HVDC system developed in DIg......SILIENT PowerFactory. The results show that the proposed coordinated frequency control method performs effectively at different wind speeds and minimises the secondary effects on frequency and DC voltage....

A search for transit timing variation

Directory of Open Access Journals (Sweden)

Kramm U.

2011-02-01

Full Text Available Photometric follow-ups of transiting exoplanets (TEPs may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. In 2009 we launched an international observing campaign, the aim of which is to detect and characterise signals of transit timing variation (TTV in selected TEPs. The programme is realised by collecting data from 0.6-2.2-m telescopes spread worldwide at different longitudes. We present our observing strategy and summarise first results for WASP-3b with evidence for a 15 Earth-mass perturber in an outer 2:1 orbital resonance.

Lack of circadian variation in the activity of the autonomic nervous system after major abdominal operations

DEFF Research Database (Denmark)

Gögenur, Ismail; Rosenberg-Adamsen, Susan; Lie, Claus

2002-01-01

OBJECTIVE: Most sudden postoperative deaths occur during the night and we conjectured that this was associated with circadian variations in the autonomic nervous tone, reflected in heart rate variability. DESIGN: Prospective clinical study. SETTINGS: University hospital, Denmark. SUBJECTS: 44...... OUTCOME MEASURES: Heart rate and heart rate variability. RESULTS: Circadian variation calculated from the SDNN (p = 0.43) the pNN50 (p = 0.11), the RMSSD (p = 0.47), and mean NN:SDNN ratio (p = 0.13) was absent postoperatively. Circadian variation in the heart rate was present but was set on a higher...... level compared with reference values. CONCLUSION: After major abdominal operations there was a lack of circadian variation in the autonomic nervous tone....

Atmospheric diurnal variations observed with GPS radio occultation soundings

Directory of Open Access Journals (Sweden)

F. Xie

2010-07-01

Full Text Available The diurnal variation, driven by solar forcing, is a fundamental mode in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology, Ionosphere and Climate provide nearly uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal variations of temperature and refractivity from three-year (2007–2009 COSMIC RO measurements in the troposphere and stratosphere between 30° S and 30° N. The RO observations reveal both propagating and trapped vertical structures of diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity shows the minimum around 14 km and increases to a local maximum around 32 km in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from stratopause to the upper troposphere with a vertical wavelength of about 25 km. At ~32 km the seasonal variation of the tidal amplitude maximizes at the opposite side of the equator relative to the solar forcing. The vertical structure of tidal amplitude shows strong seasonal variations and becomes asymmetric along the equator and tilted toward the summer hemisphere in the solstice months. Such asymmetry becomes less prominent in equinox months.

Temporal variation in organic carbon stable isotope compositions of lacustrine sediments from sub-arid northern Tanzania

International Nuclear Information System (INIS)

Muzuka, A.N.N.; Nyandwi, N.

2002-01-01

The stable isotope compositions for four sediment cores recovered from three shallow lakes located in the Ngorongoro crater (Lake Magat) and head of the Olduvai Gorge (Lakes Ndutu and Messak) are used to document climatic changes in sub-arid northern Tanzania during the late Pleistocene-Holocene period. The two lakes, which are located on the head of the Olduvai Gorge about 1 km apart and 100 km from the Ngorongoro Crater, were probably once one lake during periods of high precipitation. All four cores were collected using a flow-through type of corer, and sub-sampled every 10 cm with each sample representing a homogenate of 1 cm. Two cores (40 cm and 500 cm long) were collected from Lake Magat, and AMS 14 C age on total organic matter (OM) for a nearby core collected about 1 m apart indicate that the sedimentation rate at these sites is approximately 17 cm/ka. Assuming that these sites have a constant rate of sedimentation, the analysed long core represents sediments that were deposited during the late Pleistocene-Holocene period. The δ 13 C for 40 cm long core shows a downcore increase, with δ-values ranging from -21 per mille to -12.5 per mille. A similar downcore increase in 13 C values is observable for the 500 cm long core. Apart from this general tend, this core also shows three peaks of low δ-values centred at 200 cm, 380 cm and 490 cm. A general downcore increase in the 13 C for the two cores from the Ngorongoro crater suggests changes in the relative proportion of C 3 and C 4 , probably indicating changes in precipitation and lake levels in the area. High precipitation and lake levels being associated with deposition of OM depleted in 13 C. Although, diagenetic changes might have contributed to the observed trend, but a change of up to 7 per mille cannot solely be attributed to diagenetic changes. High content of organic carbon and nitrogen in sections enriched in 13 C excludes the possibility of diagenetic effects. Although record from Lake Ndutu is not a continuous one (gaps in between), the δ 13 C values shows a general downcore decrease contrary to the Ngorongoro crater record. This general trend is punctuated by periods of above normal enrichment in 13 C, and δ 13 C values are as high as -6 per mille. Peaks enriched in 13 C probably indicate periods of reduced precipitation, where phytoplankton used dissolved bicarbonate rather than dissolved atmospheric CO 2 . A general downcore decrease may probably indicate either an increase in precipitation over time or diagenetic effects. It has been shown that diagenetic effect is significant in sediments poor in OM. A downcore decrease in δ 13 C values associated with a low contents of organic carbon and nitrogen that shows a downcore decrease, probably is an indication of diagenetic changes. A core from Lake Messak shows near constant δ 13 C values around -19 per mille, with exception of two peaks depleted in 13 C at about 120 cm and 240 cm. Moreover, the contents of organic carbon and nitrogen for this lake are low relative to other sites. Sections depleted in 13 C were propably deposited when lake levels were high and a result of increase in precipitation. 210 Pb activity for the upper 50 cm shows that the sediments from Lake Ndutu have been recently deposited while that of Lake Messak are older. Owing to the lack of good chronology, intercore correlation is not possible. However, all three long cores point to a significant change in paleoclimatic conditions that were most likely associated with changes in the vegetation cover. (author)

The organic carbon isotope of lacustrine sediments of the Upper Shahejie formation in Huanghua Depression: a record of sedimentary environment and productivity of an ancient lake

International Nuclear Information System (INIS)

Fei, Weiwei; Huang, Xiaoyan; Dai, Na; Zhong, Ningning

2013-01-01

Huanghua depression was one of the largest Paleogene rift lakes in Bohai Bay basin, eastern China. The lake had broad area and deep water in the period of development peak—Oligocene 36~38Ma B.C., when organic-rich mudstones of upper Shahejie Formation formed. Twenty eight distal lake facie samples of the upper Shahejie Formation from Well GS35 were analyzed for organic carbon isotope, TOC, hydrogen index and trace elements in order to investigate the controls of organic carbon accumulation in the lake. The results show that lacustrine mudstones in the middile member of the upper Shahejie Formation have a heavy organic carbon isotope (-28.6 ‰ to -21.1 ‰) and a intense fractionation which is more than 7‰. In addition, it shows a good positive correlation with the total organic carbon (TOC) (Figure 1). Organic petrographic and organic geochemical analysis indicate that the biological inputs of the mudstone is dominated by algae and other aquatic organisms, and a low content of gammacerane prove the water is freshwater-brackish, so terrigenous organic matter and water salinity have little effect on its organic carbon isotope composition (δ"1"3C_o_r_g). It has well been documented that the climate in Bohai Bay basin was warm and humid during deposition of the upper Shahejie Formation, and the temperature did not change dramatically at that time (TaoZ et al., 2005). Ultimately, the heavy carbon isotope values of lacustrine organic matter may indicate the high productivity of ancient lakes. The good correlation between total organic carbon (TOC) and organic carbon isotope (δ"1"3C_o_r_g) as well as the widely existed organic-rich lamellae of the mudstone are the strong evidence for high paleoproductivity of the upper Shahejie Formation in Huanghua Depression during the deposition period. (1) Organic-rich lamellae of the mudstone formed in anoxia and stable environment have been recognized as the best evidence of high paleoproductivity. The presence of organic

Cordova: web-based management of genetic variation data.

Science.gov (United States)

Ephraim, Sean S; Anand, Nikhil; DeLuca, Adam P; Taylor, Kyle R; Kolbe, Diana L; Simpson, Allen C; Azaiez, Hela; Sloan, Christina M; Shearer, A Eliot; Hallier, Andrea R; Casavant, Thomas L; Scheetz, Todd E; Smith, Richard J H; Braun, Terry A

2014-12-01

Cordova is an out-of-the-box solution for building and maintaining an online database of genetic variations integrated with pathogenicity prediction results from popular algorithms. Our primary motivation for developing this system is to aid researchers and clinician-scientists in determining the clinical significance of genetic variations. To achieve this goal, Cordova provides an interface to review and manually or computationally curate genetic variation data as well as share it for clinical diagnostics and the advancement of research. Cordova is open source under the MIT license and is freely available for download at https://github.com/clcg/cordova. Published by Oxford University Press. This work is written by US Government employees and is in the public domain in the US.

Multiple-scale hydraulic characterization of a surficial clayey aquitard overlying a regional aquifer in Louisiana