WorldWideScience

Sample records for shapes spatial distribution

  1. 3D shape representation with spatial probabilistic distribution of intrinsic shape keypoints

    Science.gov (United States)

    Ghorpade, Vijaya K.; Checchin, Paul; Malaterre, Laurent; Trassoudaine, Laurent

    2017-12-01

    The accelerated advancement in modeling, digitizing, and visualizing techniques for 3D shapes has led to an increasing amount of 3D models creation and usage, thanks to the 3D sensors which are readily available and easy to utilize. As a result, determining the similarity between 3D shapes has become consequential and is a fundamental task in shape-based recognition, retrieval, clustering, and classification. Several decades of research in Content-Based Information Retrieval (CBIR) has resulted in diverse techniques for 2D and 3D shape or object classification/retrieval and many benchmark data sets. In this article, a novel technique for 3D shape representation and object classification has been proposed based on analyses of spatial, geometric distributions of 3D keypoints. These distributions capture the intrinsic geometric structure of 3D objects. The result of the approach is a probability distribution function (PDF) produced from spatial disposition of 3D keypoints, keypoints which are stable on object surface and invariant to pose changes. Each class/instance of an object can be uniquely represented by a PDF. This shape representation is robust yet with a simple idea, easy to implement but fast enough to compute. Both Euclidean and topological space on object's surface are considered to build the PDFs. Topology-based geodesic distances between keypoints exploit the non-planar surface properties of the object. The performance of the novel shape signature is tested with object classification accuracy. The classification efficacy of the new shape analysis method is evaluated on a new dataset acquired with a Time-of-Flight camera, and also, a comparative evaluation on a standard benchmark dataset with state-of-the-art methods is performed. Experimental results demonstrate superior classification performance of the new approach on RGB-D dataset and depth data.

  2. Spatial distribution and functional significance of leaf lamina shape in Amazonian forest trees

    Directory of Open Access Journals (Sweden)

    A. C. M. Malhado

    2009-08-01

    Full Text Available Leaves in tropical forests come in an enormous variety of sizes and shapes, each of which can be ultimately viewed as an adaptation to the complex problem of optimising the capture of light for photosynthesis. However, the fact that many different shape "strategies" coexist within a habitat demonstrate that there are many other intrinsic and extrinsic factors involved, such as the differential investment in support tissues required for different leaf lamina shapes. Here, we take a macrogeographic approach to understanding the function of different lamina shape categories. Specifically, we use 106 permanent plots spread across the Amazon rainforest basin to: 1 describe the geographic distribution of some simple metrics of lamina shape in plots from across Amazonia, and; 2 identify and quantify relationships between key environmental parameters and lamina shape in tropical forests. Because the plots are not randomly distributed across the study area, achieving this latter objective requires the use of statistics that can account for spatial auto-correlation. We found that between 60–70% of the 2791 species and 83 908 individual trees in the dataset could be classified as having elliptic leaves (= the widest part of the leaf is on an axis in the middle fifth of the long axis of the leaf. Furthermore, the average Amazonian tree leaf is 2.5 times longer than it is wide and has an entire margin. Contrary to theoretical expectations we found little support for the hypothesis that narrow leaves are an adaptation to dry conditions. However, we did find strong regional patterns in leaf lamina length-width ratios and several significant correlations with precipitation variables suggesting that water availability may be exerting an as yet unrecognised selective pressure on leaf shape of rainforest trees. Some support was found for the hypothesis that narrow leaves are an adaptation to low nutrient soils. Furthermore, we found a strong correlation between

  3. Longitudinal and vertical spatial gradients in the distribution of fish within a canyon-shaped reservoir

    Czech Academy of Sciences Publication Activity Database

    Vašek, Mojmír; Kubečka, J.; Peterka, Jiří; Čech, Martin; Draštík, Vladislav; Hladík, Milan; Prchalová, Marie; Frouzová, Jaroslava

    2004-01-01

    Roč. 89, č. 4 (2004), s. 352-362 ISSN 1434-2944 R&D Projects: GA AV ČR(CZ) IBS6017004 Keywords : fish distribution * spatial heterogeneity * reservoirs Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.742, year: 2004

  4. Role of Environmental Factors in Shaping Spatial Distribution of Salmonella enterica Serovar Typhi, Fiji.

    Science.gov (United States)

    de Alwis, Ruklanthi; Watson, Conall; Nikolay, Birgit; Lowry, John H; Thieu, Nga Tran Vu; Van, Tan Trinh; Ngoc, Dung Tran Thi; Rawalai, Kitione; Taufa, Mere; Coriakula, Jerimaia; Lau, Colleen L; Nilles, Eric J; Edmunds, W John; Kama, Mike; Baker, Stephen; Cano, Jorge

    2018-02-01

    Fiji recently experienced a sharp increase in reported typhoid fever cases. To investigate geographic distribution and environmental risk factors associated with Salmonella enterica serovar Typhi infection, we conducted a cross-sectional cluster survey with associated serologic testing for Vi capsular antigen-specific antibodies (a marker for exposure to Salmonella Typhi in Fiji in 2013. Hotspots with high seroprevalence of Vi-specific antibodies were identified in northeastern mainland Fiji. Risk for Vi seropositivity increased with increased annual rainfall (odds ratio [OR] 1.26/quintile increase, 95% CI 1.12-1.42), and decreased with increased distance from major rivers and creeks (OR 0.89/km increase, 95% CI 0.80-0.99) and distance to modeled flood-risk areas (OR 0.80/quintile increase, 95% CI 0.69-0.92) after being adjusted for age, typhoid fever vaccination, and home toilet type. Risk for exposure to Salmonella Typhi and its spatial distribution in Fiji are driven by environmental factors. Our findings can directly affect typhoid fever control efforts in Fiji.

  5. Spatial distribution

    DEFF Research Database (Denmark)

    Borregaard, Michael Krabbe; Hendrichsen, Ditte Katrine; Nachman, Gøsta Støger

    2008-01-01

    populations reflects the location and fragmentation pattern of the habitat types preferred by the species, and the complex dynamics of migration, colonization, and population growth taking place over the landscape. Within these, individuals are distributed among each other in regular or clumped patterns...

  6. Spatial Distribution of Transverse Dispersion Coefficients at U-shaped Bend Confluence with 60° Junction Angle

    Science.gov (United States)

    Zhao, X. X.; Gu, L.; Dai, B.

    2017-10-01

    The confluence of bend channel and the tributary is fairlycommon in nature. At present the study about the dispersion capacity of pollutants in the bend confluence is very limited. In this paper, a three-dimensional numerical model was established to explore the hydraulic characteristics such as velocity distribution and circulation structure of the different sections in the U-shaped bend confluence. Then the transverse dispersion coefficient was calculated using the dispersion tensor method and N-zone model on the base of flow structure data, and its spatial distribution along the bend is analyze. The results show that there is a significant difference in the flow structure of each section at the U-shaped bend confluence, especially before and after the junction of tributary.The peak value location of the transverse dispersion coefficient at the cross section appears near the inner bank. Along the bend channel, the transverse dispersion coefficient tends to increase first and then decrease, and the maximum value of the section appears before the bend apex where the tributary feeding into the main channel.

  7. Three-dimensional shapes and spatial distributions of Pt and PtCr catalyst nanoparticles on carbon black

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Dunin-Borkowski, Rafal E.; Ozkaya, D.

    2008-01-01

    High-angle annular dark-field scanning transmission electron microscopy tomography is applied to the study of Pt and PtCr nanoparticles supported on carbon black, which are used as heterogeneous catalysts in the electrodes of proton exchange membrane fuel cells. By using electron tomography......, the three-dimensional architecture of the heterogeneous catalyst system can be determined, providing high-spatial-resolution information about the shapes, faceting and crystallographies of 5-20 nm single and multiply twinned catalyst particles, as well as their positions with respect to the carbon support....... Approaches that can be used to provide improved information about the distribution and orientation of the particles on their support are proposed and discussed. Our results show that electron tomography provides important information that is complementary to high-resolution lattice imaging. Both techniques...

  8. Spatial distribution of aquatic insects

    DEFF Research Database (Denmark)

    Iversen, Lars Lønsmann

    and shape the habitat requirements and distribution of one of the most affected groups of freshwater species: aquatic insects. It comprises four chapters each addressing different spatial factors in relation to the occurrence of aquatic insects in Europe. Chapter I examine two spatial ecological processes...... niche is derived from local distribution patterns, without incorporating landscape history it can lead to an erroneous niche definition. Chapter III provides some of the first evidence for differences in dispersal phenology related to flight potential in aquatic insects. The chapter highlights...

  9. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  10. Highly Cross-Linked Polyethylene in Total Hip and Knee Replacement: Spatial Distribution of Molecular Orientation and Shape Recovery Behavior

    Directory of Open Access Journals (Sweden)

    Yasuhito Takahashi

    2014-01-01

    Full Text Available The present study investigated effects of processing procedures on morphology of highly cross-linked and re-melted UHMWPE (XLPE in total hip and knee arthroplasty (THA, TKA. The shape recovery behavior was also monitored via uniaxial compression test at room temperature after non-destructive characterizations of the in-depth microstructure by confocal/polarized Raman spectroscopy. The goal of this study was to relate the manufacturing-induced morphology to the in vivo micromechanical performance, and ultimately to explore an optimal structure in each alternative joint bearing. It was clearly confirmed that the investigated XLPE hip and knee implants, which were produced from different orthopaedic grade resins (GUR 1050 and GUR 1020, consisted of two structural regions in the as-received states: the near-surface transitional anisotropic layer (≈100 μm thickness and the bulk isotropic structural region. These XLPEs exhibited a different crystalline anisotropy and molecular texture within the near-surface layers. In addition, the knee insert showed a slightly higher efficiency of shape recovery against the applied strain over the hip liner owing to a markedly higher percentage of the bulk amorphous phase with intermolecular cross-linking. The quantitative data presented in this study might contribute to construct manufacturing strategies for further rationalized structures as alternative bearings in THA and TKA.

  11. Multicriteria optimization of the spatial dose distribution

    Energy Technology Data Exchange (ETDEWEB)

    Schlaefer, Alexander [Medical Robotics Group, Universität zu Lübeck, Lübeck 23562, Germany and Institute of Medical Technology, Hamburg University of Technology, Hamburg 21073 (Germany); Viulet, Tiberiu [Medical Robotics Group, Universität zu Lübeck, Lübeck 23562 (Germany); Muacevic, Alexander; Fürweger, Christoph [European CyberKnife Center Munich, Munich 81377 (Germany)

    2013-12-15

    Purpose: Treatment planning for radiation therapy involves trade-offs with respect to different clinical goals. Typically, the dose distribution is evaluated based on few statistics and dose–volume histograms. Particularly for stereotactic treatments, the spatial dose distribution represents further criteria, e.g., when considering the gradient between subregions of volumes of interest. The authors have studied how to consider the spatial dose distribution using a multicriteria optimization approach.Methods: The authors have extended a stepwise multicriteria optimization approach to include criteria with respect to the local dose distribution. Based on a three-dimensional visualization of the dose the authors use a software tool allowing interaction with the dose distribution to map objectives with respect to its shape to a constrained optimization problem. Similarly, conflicting criteria are highlighted and the planner decides if and where to relax the shape of the dose distribution.Results: To demonstrate the potential of spatial multicriteria optimization, the tool was applied to a prostate and meningioma case. For the prostate case, local sparing of the rectal wall and shaping of a boost volume are achieved through local relaxations and while maintaining the remaining dose distribution. For the meningioma, target coverage is improved by compromising low dose conformality toward noncritical structures. A comparison of dose–volume histograms illustrates the importance of spatial information for achieving the trade-offs.Conclusions: The results show that it is possible to consider the location of conflicting criteria during treatment planning. Particularly, it is possible to conserve already achieved goals with respect to the dose distribution, to visualize potential trade-offs, and to relax constraints locally. Hence, the proposed approach facilitates a systematic exploration of the optimal shape of the dose distribution.

  12. Multicriteria optimization of the spatial dose distribution

    International Nuclear Information System (INIS)

    Schlaefer, Alexander; Viulet, Tiberiu; Muacevic, Alexander; Fürweger, Christoph

    2013-01-01

    Purpose: Treatment planning for radiation therapy involves trade-offs with respect to different clinical goals. Typically, the dose distribution is evaluated based on few statistics and dose–volume histograms. Particularly for stereotactic treatments, the spatial dose distribution represents further criteria, e.g., when considering the gradient between subregions of volumes of interest. The authors have studied how to consider the spatial dose distribution using a multicriteria optimization approach.Methods: The authors have extended a stepwise multicriteria optimization approach to include criteria with respect to the local dose distribution. Based on a three-dimensional visualization of the dose the authors use a software tool allowing interaction with the dose distribution to map objectives with respect to its shape to a constrained optimization problem. Similarly, conflicting criteria are highlighted and the planner decides if and where to relax the shape of the dose distribution.Results: To demonstrate the potential of spatial multicriteria optimization, the tool was applied to a prostate and meningioma case. For the prostate case, local sparing of the rectal wall and shaping of a boost volume are achieved through local relaxations and while maintaining the remaining dose distribution. For the meningioma, target coverage is improved by compromising low dose conformality toward noncritical structures. A comparison of dose–volume histograms illustrates the importance of spatial information for achieving the trade-offs.Conclusions: The results show that it is possible to consider the location of conflicting criteria during treatment planning. Particularly, it is possible to conserve already achieved goals with respect to the dose distribution, to visualize potential trade-offs, and to relax constraints locally. Hence, the proposed approach facilitates a systematic exploration of the optimal shape of the dose distribution

  13. Shaped input distributions for structural damage localization

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Bernal, Dionisio; Damkilde, Lars

    2018-01-01

    localization method is cast, which operates on the premise of shaping inputs—whose spatial distribution is fixed—by use of a theoretical model such that these inputs, in one structural subdomain at the time, suppress certain steady-state vibration quantities (depending on the type of damage one seeks...... patterns, which results in a system identification-free procedure whose primary merits, besides avoiding the typical bottleneck of system identification, include a low demand on output sensors, robustness towards noise, and conceptual simplicity. The applicability of the method is verified in the context...

  14. [Distribution of spatial attention in position recognition].

    Science.gov (United States)

    Kumada, T; Kikuchi, T

    1988-06-01

    Spatial limitation in visual information processing was examined with dot-in-matrix patterns by using a probe recognition procedure. The independent variables were the number (1-16 dots) and the position of target dots. Subjects were four undergraduate students. The data were analyzed and discussed from three points of view; span of attention, spatial limitation of recognition and visual attention. The following became clear: First, the span of position recognition was 4.8. Second, "spatial span of attention" was defined as the range of dot positions at which subjects can perceive target dots with 75% or more accuracy. It extended around the fixation point and shrinked with the increase of the number of target dots. Finally, the distribution of spatial attention was estimated for each target dot condition under the assumption that the hit RT at each probe position reflects the amount of attention allocated there. Distributions estimated were cone-shaped, and the height and extent changed with the number of target dots. It was suggested that spatial limitation (i.e. spatial span of attention) in the processing of spatial positions can be explained by the notion of distribution of spatial attention.

  15. Inferring processes from spatial patterns: the role of directional and non-directional forces in shaping fish larvae distribution in a freshwater lake system.

    Directory of Open Access Journals (Sweden)

    Andrea Bertolo

    Full Text Available Larval dispersal is a crucial factor for fish recruitment. For fishes with relatively small-bodied larvae, drift has the potential to play a more important role than active habitat selection in determining larval dispersal; therefore, we expect small-bodied fish larvae to be poorly associated with habitat characteristics. To test this hypothesis, we used as model yellow perch (Perca flavescens, whose larvae are among the smallest among freshwater temperate fishes. Thus, we analysed the habitat association of yellow perch larvae at multiple spatial scales in a large shallow fluvial lake by explicitly modelling directional (e.g. due to water currents and non-directional (e.g. due to aggregation spatial patterns. This allowed us to indirectly assess the relative roles of drift (directional process and potential habitat choice on larval dispersal. Our results give weak support to the drift hypothesis, whereas yellow perch show a strong habitat association at unexpectedly small sizes, when compared to other systems. We found consistent non-directional patterns in larvae distributions at both broad and medium spatial scales but only few significant directional components. The environmental variables alone (e.g. vegetation generally explained a significant and biologically relevant fraction of the variation in fish larvae distribution data. These results suggest that (i drift plays a minor role in this shallow system, (ii larvae display spatial patterns that only partially covary with environmental variables, and (iii larvae are associated to specific habitats. By suggesting that habitat association potentially includes an active choice component for yellow perch larvae, our results shed new light on the ecology of freshwater fish larvae and should help in building more realistic recruitment models.

  16. Intrinsic and extrinsic factors act at different spatial and temporal scales to shape population structure, distribution and speciation in Italian Barbus (Osteichthyes: Cyprinidae).

    Science.gov (United States)

    Buonerba, Luca; Zaccara, Serena; Delmastro, Giovanni B; Lorenzoni, Massimo; Salzburger, Walter; Gante, Hugo F

    2015-08-01

    Previous studies have given substantial attention to external factors that affect the distribution and diversification of freshwater fish in Europe and North America, in particular Pleistocene and Holocene glacial cycles. In the present paper we examine sequence variation at one mitochondrial and four nuclear loci (over 3 kbp) from populations sampled across several drainages of all species of Barbus known to inhabit Italian freshwaters (introduced B. barbus and native B. balcanicus, B. caninus, B. plebejus and B. tyberinus). By comparing species with distinct ecological preferences (rheophilic and fluvio-lacustrine) and using a fossil-calibrated phylogeny we gained considerable insight about the intrinsic and extrinsic processes shaping barbel distribution, population structure and speciation. We found that timescales of Italian barbel diversification are older than previously thought, starting in the Early Miocene, and involving local and regional tectonism and basin paleo-evolution rather than Pleistocene glacial cycles. Conversely, more recent environmental factors associated with glaciation-deglaciation cycles have influenced species distributions. These events had a more marked impact on fluvio-lacustrine than on rheophilic species by means of river confluence at low sea levels. We show that genetic structure is influenced by species ecology: populations of small rheophilic species inhabiting upper river stretches of large basins are less connected and more differentiated than large fluvio-lacustrine species that inhabit lower river courses. We report the existence of both natural and human-induced interspecific gene flow, which could have great impacts on the evolution and persistence of species involved. In addition, we provide evidence that B. tyberinus is genetically distinguishable from all other Italian taxa and that its morphological similarity to B. plebejus and intermediacy with B. caninus are best explained by recent common ancestry and similar

  17. Shape of Pion Distribution Amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  18. Spatial distribution of the .i.Daphnia longispina./i. species complex and other planktonic crustaceans in the heterogeneous environment of canyon-shaped reservoirs

    Czech Academy of Sciences Publication Activity Database

    Seďa, Jaromír; Petrusek, A.; Macháček, Jiří; Šmilauer, P.

    2007-01-01

    Roč. 29, č. 7 (2007), s. 619-628 ISSN 0142-7873 R&D Projects: GA ČR(CZ) GA206/04/0190 Institutional research plan: CEZ:AV0Z60170517 Keywords : Daphnia longispina species complex * canyon-shaped reservoirs Subject RIV: DA - Hydrology ; Limnology Impact factor: 1.897, year: 2007

  19. Spatial Distribution of Market Centers

    Directory of Open Access Journals (Sweden)

    Md. Morshedul Islam

    2018-03-01

    Full Text Available The present study is an attempt to find the location pattern, distribution and their sphere of influences of market centers in Rangpur City Corporation, Bangladesh. Rangpur is facing some problems like a traffic jam, noisy environment, population pressure etc due to the over population in full day long in the center of this city, all of the whole sale and retail sale markets are located in the middle. Location of Market is always influencing the daily life of the city population who are directly or indirectly connected with the market. If the market strategically distributed in an area they don’t face such kind of problems. Analysis or investigation shows that at about all of the market centers are located in the center of Rangpur and in the residential area of Rangpur. The maximum 67% market centers are found in the high-income residential area. Rangpur City Corporation, Bangladesh Bureau of Statistics and survey of Bangladesh provided the maps, reports and relevant documents of the study. The spatial dispersion pattern of market centers is clustered together at one place 0.33(Nearest Neighbor Index value, R found in the study area. Geographical Information System (GIS and other software also used to analyze the maps and diagrams. Investigation refers that, the market of Rangpur city have a clustered pattern and different levels of market centers found on the bases of centrality scores. By this centrality scores or levels, found the variation of influencing spheres of market centers in Rangpur City.

  20. Brownian shape motion: Fission fragment mass distributions

    Directory of Open Access Journals (Sweden)

    Sierk Arnold J.

    2012-02-01

    Full Text Available It was recently shown that remarkably accurate fission-fragment mass distributions can be obtained by treating the nuclear shape evolution as a Brownian walk on previously calculated five-dimensional potential-energy surfaces; the current status of this novel method is described here.

  1. HEp-2 Cell Classification Using Shape Index Histograms With Donut-Shaped Spatial Pooling

    DEFF Research Database (Denmark)

    Larsen, Anders Boesen Lindbo; Vestergaard, Jacob Schack; Larsen, Rasmus

    2014-01-01

    introduce a spatial decomposition scheme which is radially symmetric and suitable for cell images. The spatial decomposition is performed using donut-shaped pooling regions of varying sizes when gathering histogram contributions. We evaluate our method using both the ICIP 2013 and the ICPR 2012 competition...

  2. Spatial distribution of thermal energy in equilibrium.

    Science.gov (United States)

    Bar-Sinai, Yohai; Bouchbinder, Eran

    2015-06-01

    The equipartition theorem states that in equilibrium, thermal energy is equally distributed among uncoupled degrees of freedom that appear quadratically in the system's Hamiltonian. However, for spatially coupled degrees of freedom, such as interacting particles, one may speculate that the spatial distribution of thermal energy may differ from the value predicted by equipartition, possibly quite substantially in strongly inhomogeneous or disordered systems. Here we show that for systems undergoing simple Gaussian fluctuations around an equilibrium state, the spatial distribution is universally bounded from above by 1/2k(B)T. We further show that in one-dimensional systems with short-range interactions, the thermal energy is equally partitioned even for coupled degrees of freedom in the thermodynamic limit and that in higher dimensions nontrivial spatial distributions emerge. Some implications are discussed.

  3. Spatial Resolution of a Wedge Shaped MSGC Module

    CERN Document Server

    Bachmann, Sebastian

    1997-01-01

    A banana shaped closed design MSGC detector module was tested together with silicon detectors and other MSGCs in a 100 GeV muon beam. Despite of an undesirable geometry of the test setup, a spatial resolution below 40 micron m was reached. The efficiency of the module, defined by track reconstruction, shows to be 95,6 percent

  4. Dengue Vectors and their Spatial Distribution.

    Science.gov (United States)

    Higa, Yukiko

    2011-12-01

    The distribution of dengue vectors, Ae. aegypti and Ae. albopictus, is affected by climatic factors. In addition, since their life cycles are well adapted to the human environment, environmental changes resulting from human activity such as urbanization exert a great impact on vector distribution. The different responses of Ae. aegypti and Ae albopictus to various environments result in a difference in spatial distribution along north-south and urban-rural gradients, and between the indoors and outdoors. In the north-south gradient, climate associated with survival is an important factor in spatial distribution. In the urban-rural gradient, different distribution reflects a difference in adult niches and is modified by geographic and human factors. The direct response of the two species to the environment around houses is related to different spatial distribution indoors and outdoors. Dengue viruses circulate mainly between human and vector mosquitoes, and the vector presence is a limiting factor of transmission. Therefore, spatial distribution of dengue vectors is a significant concern in the epidemiology of the disease.Current technologies such as GIS, satellite imagery and statistical models allow researchers to predict the spatial distribution of vectors in the changing environment. Although it is difficult to confirm the actual effect of environmental and climate changes on vector abundance and vector-borne diseases, environmental changes caused by humans and human behavioral changes due to climate change can be expected to exert an impact on dengue vectors. Longitudinal monitoring of dengue vectors and viruses is therefore necessary.

  5. Macroecological factors shape local-scale spatial patterns in agriculturalist settlements.

    Science.gov (United States)

    Tao, Tingting; Abades, Sebastián; Teng, Shuqing; Huang, Zheng Y X; Reino, Luís; Chen, Bin J W; Zhang, Yong; Xu, Chi; Svenning, Jens-Christian

    2017-11-15

    Macro-scale patterns of human systems ranging from population distribution to linguistic diversity have attracted recent attention, giving rise to the suggestion that macroecological rules shape the assembly of human societies. However, in which aspects the geography of our own species is shaped by macroecological factors remains poorly understood. Here, we provide a first demonstration that macroecological factors shape strong local-scale spatial patterns in human settlement systems, through an analysis of spatial patterns in agriculturalist settlements in eastern mainland China based on high-resolution Google Earth images. We used spatial point pattern analysis to show that settlement spatial patterns are characterized by over-dispersion at fine spatial scales (0.05-1.4 km), consistent with territory segregation, and clumping at coarser spatial scales beyond the over-dispersion signals, indicating territorial clustering. Statistical modelling shows that, at macroscales, potential evapotranspiration and topographic heterogeneity have negative effects on territory size, but positive effects on territorial clustering. These relationships are in line with predictions from territory theory for hunter-gatherers as well as for many animal species. Our results help to disentangle the complex interactions between intrinsic spatial processes in agriculturalist societies and external forcing by macroecological factors. While one may speculate that humans can escape ecological constraints because of unique abilities for environmental modification and globalized resource transportation, our work highlights that universal macroecological principles still shape the geography of current human agricultural societies. © 2017 The Author(s).

  6. Hazard tolerance of spatially distributed complex networks

    International Nuclear Information System (INIS)

    Dunn, Sarah; Wilkinson, Sean

    2017-01-01

    In this paper, we present a new methodology for quantifying the reliability of complex systems, using techniques from network graph theory. In recent years, network theory has been applied to many areas of research and has allowed us to gain insight into the behaviour of real systems that would otherwise be difficult or impossible to analyse, for example increasingly complex infrastructure systems. Although this work has made great advances in understanding complex systems, the vast majority of these studies only consider a systems topological reliability and largely ignore their spatial component. It has been shown that the omission of this spatial component can have potentially devastating consequences. In this paper, we propose a number of algorithms for generating a range of synthetic spatial networks with different topological and spatial characteristics and identify real-world networks that share the same characteristics. We assess the influence of nodal location and the spatial distribution of highly connected nodes on hazard tolerance by comparing our generic networks to benchmark networks. We discuss the relevance of these findings for real world networks and show that the combination of topological and spatial configurations renders many real world networks vulnerable to certain spatial hazards. - Highlights: • We develop a method for quantifying the reliability of real-world systems. • We assess the spatial resilience of synthetic spatially distributed networks. • We form algorithms to generate spatial scale-free and exponential networks. • We show how these “synthetic” networks are proxies for real world systems. • Conclude that many real world systems are vulnerable to spatially coherent hazard.

  7. Spatial resolution of wedge shaped silicon microstrip detectors

    Science.gov (United States)

    Antičić, T.; Barnett, B.; Blumenfeld, B.; Chien, C.-Y.; Fisher, P.; Gougas, A.; Krizmanic, J.; Madansky, L.; Newman, D.; Orndorff, J.; Pevsner, A.; Spangler, J.

    1995-02-01

    Several wedge-shaped silicon microstrip detectors with pitches from 30 to 100 μm have been designed by our group and beam tested at the CERN SPS. We find the spatial resolution σ becomes larger at the rate of 0.21 μm per 1 μm increase in pitch, but the number of strips per cluster remains about the same as the pitch varies from 30 to 100 μm.

  8. Spatial resolution of wedge shaped silicon microstrip detectors

    International Nuclear Information System (INIS)

    Anticic, T.; Barnett, B.; Blumenfeld, B.; Chien, C.Y.; Fisher, P.; Gougas, A.; Krizmanic, J.; Madansky, L.; Newman, D.; Orndorff, J.; Pevsner, A.; Spangler, J.

    1995-01-01

    Several wedge-shaped silicon microstrip detectors with pitches from 30 to 100 μm have been designed by our group and beam tested at the CERN SPS. We find the spatial resolution σ becomes larger at the rate of 0.21 μm per 1 μm increase in pitch, but the number of strips per cluster remains about the same as the pitch varies from 30 to 100 μm. (orig.)

  9. Spatial distributions of niche-constructing populations

    Directory of Open Access Journals (Sweden)

    Xiaozhuo Han

    2015-12-01

    Full Text Available Niche construction theory regards organisms not only as the object of natural selection but also an active subject that can change their own selective pressure through eco-evolutionary feedbacks. Through reviewing the existing works on the theoretical models of niche construction, here we present the progress made on how niche construction influences genetic structure of spatially structured populations and the spatial-temporal dynamics of metapopulations, with special focuses on mathematical models and simulation methods. The majority of results confirmed that niche construction can significantly alter the evolutionary trajectories of structured populations. Organism-environmental interactions induced by niche construction can have profound influence on the dynamics, competition and diversity of metapopulations. It can affect fine-scale spatially distribution of species and spatial heterogeneity of the environment. We further propose a few research directions with potentials, such as applying adaptive dynamics or spatial game theory to explore the effect of niche construction on phenotypic evolution and diversification.

  10. SPATIAL DISTRIBUTION OF POVERTY AT DIFFERENT SCALES

    Directory of Open Access Journals (Sweden)

    Gandhi PAWITAN

    2010-01-01

    Full Text Available Poverty mapping is usually developed from some sources of data, such as from census and survey data. In some practical application, the poverty was measured usually by household income or expenditure of daily basic consumption. Using different scales and zoning on a particular set of spatial data may leads to problems in interpreting the results. In practice, organizations publish statistics and maps at a particular area level. Minot and Baulch (2005a discussed some consequences of using aggregated level data in poverty mapping, which may affect the validity of the output. The key point of this paper is to compare spatial distribution of the poverty at two different scale, which is the province and district level. How the spatial distribution of the poverty at province level can be use to infer the distribution at the district level. The geographical weighted regression will be applied, and the poverty data of Vietnam will be used as an illustration.

  11. Shaped input distributions for structural damage localization

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Bernal, Dionisio; Damkilde, Lars

    2018-01-01

    ). Accordingly, damage is localized when the vibration signature induced by the shaped inputs in the damaged state corresponds to that in the reference state, hereby implying that the approach does not point directly to damage. Instead, it operates with interrogation based on postulated damage patterns......, resulting in a system identification-free procedure whose primary merits, besides avoiding the typical bottleneck of system identification, include a low demand on output sensors, robustness towards noise, and conceptual simplicity. The price paid for these merits is reliance on a relatively accurate model...... of the structure in its reference state and the need for multiple controllable inputs....

  12. Spatial indoor radon distribution in Mexico City

    International Nuclear Information System (INIS)

    Franco-Marina, Francisco; Villalba-Caloca, Jaime; Segovia, Nuria; Tavera, Leticia

    2003-01-01

    We present a spatial analysis of residential radon concentrations in the Mexico City Metropolitan Area, which we intend to use to assign radon exposure in an ongoing case-control study. As part of a probabilistic household survey, carried out between May and June 1999, 501 dwellings were selected for indoor placement of solid state nuclear track detectors (LR 115) in a cup array over a period of approximately 90 days. As part of the sampling design, the city was grid partitioned into nine zones and a sample of dwellings was selected in each zone. All zones were simultaneously surveyed. The stratified sampling design allowed us to obtain radon geometric means, adjusted for household characteristics, week of detector placement and number of days of measurement for these zones. Additionally, adjusted geometric means were estimated for the 100 census tracts surveyed and this information was used to obtain a more detailed spatial distribution of residential radon levels through kriging interpolation and surface contouring. Radon levels depended on the room of placement, the floor level and the ventilation habits but not on building materials. Regarding the city zone, the highest adjusted geometric mean was found in the southwest (136 Bqm -3 ), where 46% of the households had an estimated radon level in excess of 200 Bqm -3 . In the rest of the city, the geometric mean concentration ranged between 41 and 98 Bqm -3 . A more detailed spatial distribution showed that, in general, most of the eastern and middle zones of the city had estimated radon geometric means below 74 Bqm -3 , while the western ones had geometric means above this concentration. Very high geometric means, exceeding 111 Bqm -3 and even reaching 288 Bqm -3 , are estimated for some areas located in the southern and western zones of Mexico City. The obtained spatial distribution shows that the areas with very high estimated residential radon concentrations are close to inactive volcanic mountains. We believe

  13. Revised spatially distributed global livestock emissions

    Science.gov (United States)

    Asrar, G.; Wolf, J.; West, T. O.

    2015-12-01

    Livestock play an important role in agricultural carbon cycling through consumption of biomass and emissions of methane. Quantification and spatial distribution of methane and carbon dioxide produced by livestock is needed to develop bottom-up estimates for carbon monitoring. These estimates serve as stand-alone international emissions estimates, as input to global emissions modeling, and as comparisons or constraints to flux estimates from atmospheric inversion models. Recent results for the US suggest that the 2006 IPCC default coefficients may underestimate livestock methane emissions. In this project, revised coefficients were calculated for cattle and swine in all global regions, based on reported changes in body mass, quality and quantity of feed, milk production, and management of living animals and manure for these regions. New estimates of livestock methane and carbon dioxide emissions were calculated using the revised coefficients and global livestock population data. Spatial distribution of population data and associated fluxes was conducted using the MODIS Land Cover Type 5, version 5.1 (i.e. MCD12Q1 data product), and a previously published downscaling algorithm for reconciling inventory and satellite-based land cover data at 0.05 degree resolution. Preliminary results for 2013 indicate greater emissions than those calculated using the IPCC 2006 coefficients. Global total enteric fermentation methane increased by 6%, while manure management methane increased by 38%, with variation among species and regions resulting in improved spatial distributions of livestock emissions. These new estimates of total livestock methane are comparable to other recently reported studies for the entire US and the State of California. These new regional/global estimates will improve the ability to reconcile top-down and bottom-up estimates of methane production as well as provide updated global estimates for use in development and evaluation of Earth system models.

  14. Shape and Spatially-Varying Reflectance Estimation from Virtual Exemplars.

    Science.gov (United States)

    Hui, Zhuo; Sankaranarayanan, Aswin C

    2017-10-01

    This paper addresses the problem of estimating the shape of objects that exhibit spatially-varying reflectance. We assume that multiple images of the object are obtained under a fixed view-point and varying illumination, i.e., the setting of photometric stereo. At the core of our techniques is the assumption that the BRDF at each pixel lies in the non-negative span of a known BRDF dictionary. This assumption enables a per-pixel surface normal and BRDF estimation framework that is computationally tractable and requires no initialization in spite of the underlying problem being non-convex. Our estimation framework first solves for the surface normal at each pixel using a variant of example-based photometric stereo. We design an efficient multi-scale search strategy for estimating the surface normal and subsequently, refine this estimate using a gradient descent procedure. Given the surface normal estimate, we solve for the spatially-varying BRDF by constraining the BRDF at each pixel to be in the span of the BRDF dictionary; here, we use additional priors to further regularize the solution. A hallmark of our approach is that it does not require iterative optimization techniques nor the need for careful initialization, both of which are endemic to most state-of-the-art techniques. We showcase the performance of our technique on a wide range of simulated and real scenes where we outperform competing methods.

  15. Record values from a family of J-shaped distributions

    Directory of Open Access Journals (Sweden)

    Ahmad A. Zghoul

    2013-05-01

    Full Text Available A family of J-shaped distributions has applications in life testing modeling. In this paper we study record values from this family of distributions. Based on lower records, recurrence relations and bounds as well as expressions for moments and product moments of record values are obtained, the maximum likelihood estimator of the shape parameter is derived and shown to be consistent, sufficient, complete and UMVU estimator. In addition, an application in reliability is given.

  16. Spatial distribution maps for benthic communities

    DEFF Research Database (Denmark)

    Sørensen, Per S.

    1999-01-01

    simulation, Markov random fields and Boolean models. Geostatistical simulation provides a means of assessing the variability of random field functionals such as the estimated distribution area of a benthic species. The Markov random field allows the spatial distribution of the benthic communities...... to be modelled as a less smooth or regular phenomena than assumed when using geostatistical models. The use of Markov random fields in a Markov chain Monte Carlo simulation framework enables an alternative means of assessing variability of image functionals that is based on a sound theoretical basis......-scan sonar for mapping of benthic communities remains an open task to be studied in the future. The data processing methodology developed is a contribution to the emerging field of hydroacoustic marine biology. The method of penalised maximum pseudo-likelihood for estimation of the Ising model under a huge...

  17. Diffraction characteristics of spatial and temporal Gaussian-shaped femtosecond laser pulse by rectangle reflection grating.

    Science.gov (United States)

    Liu, Guohua; Xu, Rongrong; Yu, Wenbing; Wu, Hanping

    2011-02-20

    The exact intensity distribution expression for the spatial and temporal Gaussian-shaped femtosecond laser pulse diffracted by a rectangle reflection grating is derived. The spatial and temporal diffraction characteristics are theoretically investigated in detail, and a criterion for judging whether or not the diffraction pulse is just split into two independent pulses in the temporal domain is obtained. The results show that the diffraction intensity in the temporal domain consists of three parts: the intensity diffracted by the upper reflection surface of the grating, the intensity diffracted by the nether reflection surface, and their temporal coherent intensity. The temporal coherent intensity becomes weaker, even is zero, for the higher height from the nether surface to the upper surface of the grating. The principal maximum becomes more sharply bright for the bigger waist width of the femtosecond laser pulse in the spatial domain.

  18. Spatial and temporal distribution of geophysical disasters

    Directory of Open Access Journals (Sweden)

    Cvetković Vladimir

    2013-01-01

    Full Text Available Natural disasters of all kinds (meteorological, hydrological, geophysical, climatological and biological are increasingly becoming part of everyday life of modern human. The consequences are often devastating, to the life, health and property of people, as well to the security of states and the entire international regions. In this regard, we noted the need for a comprehensive investigation of the phenomenology of natural disasters. In addition, it is particularly important to pay attention to the different factors that might correlate with each other to indicate more dubious and more original facts about their characteristics. However, as the issue of natural disasters is very wide, the subject of this paper will be forms, consequences, temporal and spatial distribution of geophysical natural disasters, while analysis of other disasters will be the subject of our future research. Using an international database on natural disasters of the centre for research on the epidemiology of disasters (CRED based in Brussels, with the support of the statistical analysis (SPSS, we tried to point out the number, trends, consequences, the spatial and temporal distribution of earthquakes, volcanic eruptions and dry mass movements in the world, from 1900 to 2013.

  19. Compressive Feedback Control Design for Spatially Distributed Systems

    Science.gov (United States)

    2017-01-03

    AFRL-AFOSR-VA-TR-2017-0004 Compressive Feedback Control Design for Spatially Distributed Systems Nader Motee LEHIGH UNIVERSITY 526 BRODHEAD AVE...0158 Compressive Feedback Control Design for Spatially Distributed Systems Program Manager: Dr. Frederick A. Leve Principle Investigator: Nader Motee...Feedback Control Design for Spatially Distributed Systems Summary of Accomplishments and Research Results 1 Systemic Performance and Robustness

  20. Detecting changes in the spatial distribution of nitrate contamination in ground water

    Science.gov (United States)

    Liu, Z.-J.; Hallberg, G.R.; Zimmerman, D.L.; Libra, R.D.

    1997-01-01

    Many studies of ground water pollution in general and nitrate contamination in particular have often relied on a one-time investigation, tracking of individual wells, or aggregate summaries. Studies of changes in spatial distribution of contaminants over time are lacking. This paper presents a method to compare spatial distributions for possible changes over time. The large-scale spatial distribution at a given time can be considered as a surface over the area (a trend surface). The changes in spatial distribution from period to period can be revealed by the differences in the shape and/or height of surfaces. If such a surface is described by a polynomial function, changes in surfaces can be detected by testing statistically for differences in their corresponding polynomial functions. This method was applied to nitrate concentration in a population of wells in an agricultural drainage basin in Iowa, sampled in three different years. For the period of 1981-1992, the large-scale spatial distribution of nitrate concentration did not show significant change in the shape of spatial surfaces; while the magnitude of nitrate concentration in the basin, or height of the computed surfaces showed significant fluctuations. The change in magnitude of nitrate concentration is closely related to climatic variations, especially in precipitation. The lack of change in the shape of spatial surfaces means that either the influence of land use/nitrogen management was overshadowed by climatic influence, or the changes in land use/management occurred in a random fashion.

  1. Scale and shape mixtures of multivariate skew-normal distributions

    KAUST Repository

    Arellano-Valle, Reinaldo B.

    2018-02-26

    We introduce a broad and flexible class of multivariate distributions obtained by both scale and shape mixtures of multivariate skew-normal distributions. We present the probabilistic properties of this family of distributions in detail and lay down the theoretical foundations for subsequent inference with this model. In particular, we study linear transformations, marginal distributions, selection representations, stochastic representations and hierarchical representations. We also describe an EM-type algorithm for maximum likelihood estimation of the parameters of the model and demonstrate its implementation on a wind dataset. Our family of multivariate distributions unifies and extends many existing models of the literature that can be seen as submodels of our proposal.

  2. Particle size and shape distributions of hammer milled pine

    Energy Technology Data Exchange (ETDEWEB)

    Westover, Tyler Lott [Idaho National Lab. (INL), Idaho Falls, ID (United States); Matthews, Austin Colter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williams, Christopher Luke [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ryan, John Chadron Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    Particle size and shape distributions impact particle heating rates and diffusion of volatized gases out of particles during fast pyrolysis conversion, and consequently must be modeled accurately in order for computational pyrolysis models to produce reliable results for bulk solid materials. For this milestone, lodge pole pine chips were ground using a Thomas-Wiley #4 mill using two screen sizes in order to produce two representative materials that are suitable for fast pyrolysis. For the first material, a 6 mm screen was employed in the mill and for the second material, a 3 mm screen was employed in the mill. Both materials were subjected to RoTap sieve analysis, and the distributions of the particle sizes and shapes were determined using digital image analysis. The results of the physical analysis will be fed into computational pyrolysis simulations to create models of materials with realistic particle size and shape distributions. This milestone was met on schedule.

  3. Derived flood frequency distributions considering individual event hydrograph shapes

    Science.gov (United States)

    Hassini, Sonia; Guo, Yiping

    2017-04-01

    Derived in this paper is the frequency distribution of the peak discharge rate of a random runoff event from a small urban catchment. The derivation follows the derived probability distribution procedure and incorporates a catchment rainfall-runoff model with approximating shapes for individual runoff event hydrographs. In the past, only simple triangular runoff event hydrograph shapes were used, in this study approximating runoff event hydrograph shapes better representing all the possibilities are considered. The resulting closed-form mathematical equations are converted to the commonly required flood frequency distributions for use in urban stormwater management studies. The analytically determined peak discharge rates of different return periods for a wide range of hypothetical catchment conditions were compared to those determined from design storm modeling. The newly derived equations generated results that are closer to those from design storm modeling and provide a better alternative for use in urban stormwater management studies.

  4. Spatial and temporal distribution of natural disasters

    Directory of Open Access Journals (Sweden)

    Cvetković Vladimir M.

    2014-01-01

    Full Text Available The subject of quantitative research is determining the spatial and temporal distribution of natural disasters worldwide for the period 1900-2013. Considering that it is a mass phenomenon, which consists of multiple units, most preferred scientific method for making conclusions on natural disasters is the statistical method. Thereby, a statistical survey has been conducted in the way that raw data about all natural disasters in the first step were downloaded (25.552 in the form of Excel file from the international database on disasters (CRED in Brussels, and then analyzed in program for statistical analysis of data SPSS. Within the geospatial distribution the total number and consequences of natural disasters were analyzed by continents. According to the same principle, within temporal analysis we examined distribution of the total number and effects of natural disasters on annual, monthly and daily levels. Statistical results of analysis clearly indicate that the number of natural disasters has increased, with their recorded maximum in the period from 2000 to 2013. Certainly, one can not absolutely say this is true in view of starting to pay serious attention to quantitative indicators. Also, it can not be said that the international database (CRED included absolutely all natural disasters in the world, considering that it was created thanks to the submission of national reports on natural disasters. Such way of data collection can have serious shortcomings, given the diverse subjectivities. In addition, the question that arises is whether most underdeveloped countries submitted their reports. Bearing in mind the increasing trend in the number and severity of natural disasters in the global geographic space, the survey results represent a good argument for initiation of serious reforms of the system of protection and rescue against natural disasters in countries around the world. Results of research impact on raising awareness among citizens

  5. Combining Shape-Changing Interfaces and Spatial Augmented Reality Enables Extended Object Appearance

    DEFF Research Database (Denmark)

    Lindlbauer, David; Grønbæk, Jens Emil; Birk, Morten

    2016-01-01

    We propose combining shape-changing interfaces and spatial augmented reality for extending the space of appearances and interactions of actuated interfaces. While shape-changing interfaces can dynamically alter the physical appearance of objects, the integration of spatial augmented reality addit...

  6. Ultrafast laser spatial beam shaping based on Zernike polynomials for surface processing.

    Science.gov (United States)

    Houzet, J; Faure, N; Larochette, M; Brulez, A-C; Benayoun, S; Mauclair, C

    2016-03-21

    In femtosecond laser machining, spatial beam shaping can be achieved with wavefront modulators. The wavefront modulator displays a pre-calculated phase mask that modulates the laser wavefront to generate a target intensity distribution in the processing plane. Due to the non-perfect optical response of wavefront modulators, the experimental distribution may significantly differ from the target, especially for continuous shapes. We propose an alternative phase mask calculation method that can be adapted to the phase modulator optical performance. From an adjustable number of Zernike polynomials according to this performance, a least square fitting algorithm numerically determines their coefficients to obtain the desired wavefront modulation. We illustrate the technique with an optically addressed liquid-crystal light valve to produce continuous intensity distributions matching a desired ablation profile, without the need of a wavefront sensor. The projection of the experimental laser distribution shows a 5% RMS error compared to the calculated one. Ablation of steel is achieved following user-defined micro-dimples and micro-grooves targets on mold surfaces. The profiles of the microgrooves and the injected polycarbonate closely match the target (RMS below 4%).

  7. Confounding environmental colour and distribution shape leads to underestimation of population extinction risk.

    Directory of Open Access Journals (Sweden)

    Mike S Fowler

    Full Text Available The colour of environmental variability influences the size of population fluctuations when filtered through density dependent dynamics, driving extinction risk through dynamical resonance. Slow fluctuations (low frequencies dominate in red environments, rapid fluctuations (high frequencies in blue environments and white environments are purely random (no frequencies dominate. Two methods are commonly employed to generate the coloured spatial and/or temporal stochastic (environmental series used in combination with population (dynamical feedback models: autoregressive [AR(1] and sinusoidal (1/f models. We show that changing environmental colour from white to red with 1/f models, and from white to red or blue with AR(1 models, generates coloured environmental series that are not normally distributed at finite time-scales, potentially confounding comparison with normally distributed white noise models. Increasing variability of sample Skewness and Kurtosis and decreasing mean Kurtosis of these series alter the frequency distribution shape of the realised values of the coloured stochastic processes. These changes in distribution shape alter patterns in the probability of single and series of extreme conditions. We show that the reduced extinction risk for undercompensating (slow growing populations in red environments previously predicted with traditional 1/f methods is an artefact of changes in the distribution shapes of the environmental series. This is demonstrated by comparison with coloured series controlled to be normally distributed using spectral mimicry. Changes in the distribution shape that arise using traditional methods lead to underestimation of extinction risk in normally distributed, red 1/f environments. AR(1 methods also underestimate extinction risks in traditionally generated red environments. This work synthesises previous results and provides further insight into the processes driving extinction risk in model populations. We

  8. Developing shape analysis tools to assist complex spatial decision making

    International Nuclear Information System (INIS)

    Mackey, H.E.; Ehler, G.B.; Cowen, D.

    1996-01-01

    The objective of this research was to develop and implement a shape identification measure within a geographic information system, specifically one that incorporates analytical modeling for site location planning. The application that was developed incorporated a location model within a raster-based GIS, which helped address critical performance issues for the decision support system. Binary matrices, which approximate the object's geometrical form, are passed over the grided data structure and allow identification of irregular and regularly shaped objects. Lastly, the issue of shape rotation is addressed and is resolved by constructing unique matrices corresponding to the object's orientation

  9. The role of biotic interactions in shaping distributions and realised assemblages of species: implications for species distribution modelling

    Science.gov (United States)

    Wisz, Mary Susanne; Pottier, Julien; Kissling, W Daniel; Pellissier, Loïc; Lenoir, Jonathan; Damgaard, Christian F; Dormann, Carsten F; Forchhammer, Mads C; Grytnes, John-Arvid; Guisan, Antoine; Heikkinen, Risto K; Høye, Toke T; Kühn, Ingolf; Luoto, Miska; Maiorano, Luigi; Nilsson, Marie-Charlotte; Normand, Signe; Öckinger, Erik; Schmidt, Niels M; Termansen, Mette; Timmermann, Allan; Wardle, David A; Aastrup, Peter; Svenning, Jens-Christian

    2013-01-01

    Predicting which species will occur together in the future, and where, remains one of the greatest challenges in ecology, and requires a sound understanding of how the abiotic and biotic environments interact with dispersal processes and history across scales. Biotic interactions and their dynamics influence species' relationships to climate, and this also has important implications for predicting future distributions of species. It is already well accepted that biotic interactions shape species' spatial distributions at local spatial extents, but the role of these interactions beyond local extents (e.g. 10 km2 to global extents) are usually dismissed as unimportant. In this review we consolidate evidence for how biotic interactions shape species distributions beyond local extents and review methods for integrating biotic interactions into species distribution modelling tools. Drawing upon evidence from contemporary and palaeoecological studies of individual species ranges, functional groups, and species richness patterns, we show that biotic interactions have clearly left their mark on species distributions and realised assemblages of species across all spatial extents. We demonstrate this with examples from within and across trophic groups. A range of species distribution modelling tools is available to quantify species environmental relationships and predict species occurrence, such as: (i) integrating pairwise dependencies, (ii) using integrative predictors, and (iii) hybridising species distribution models (SDMs) with dynamic models. These methods have typically only been applied to interacting pairs of species at a single time, require a priori ecological knowledge about which species interact, and due to data paucity must assume that biotic interactions are constant in space and time. To better inform the future development of these models across spatial scales, we call for accelerated collection of spatially and temporally explicit species data. Ideally

  10. On the spatial distributions of dense cores in Orion B

    Science.gov (United States)

    Parker, Richard J.

    2018-05-01

    We quantify the spatial distributions of dense cores in three spatially distinct areas of the Orion B star-forming region. For L1622, NGC 2068/NGC 2071, and NGC 2023/NGC 2024, we measure the amount of spatial substructure using the Q-parameter and find all three regions to be spatially substructured (Q Orion B, the mass segregation cannot be dynamical. Our results are also inconsistent with simulations in which the most massive stars form via competitive accretion, and instead hint that magnetic fields may be important in influencing the primordial spatial distributions of gas and stars in star-forming regions.

  11. RSS as a distribution medium for geo-spatial hypermedia

    DEFF Research Database (Denmark)

    Hansen, Frank Allan; Christensen, Bent Guldbjerg; Bouvin, Niels Olof

    2005-01-01

    This paper describes how the XML based RSS syndication formats used in weblogs can be utilized as the distribution medium for geo-spatial hypermedia, and how this approach can be used to create a highly distributed multi-user annotation system for geo-spatial hypermedia. It is demonstrated, how...

  12. A tutorial on Palm distributions for spatial point processes

    DEFF Research Database (Denmark)

    Coeurjolly, Jean-Francois; Møller, Jesper; Waagepetersen, Rasmus Plenge

    2017-01-01

    This tutorial provides an introduction to Palm distributions for spatial point processes. Initially, in the context of finite point processes, we give an explicit definition of Palm distributions in terms of their density functions. Then we review Palm distributions in the general case. Finally, we...... discuss some examples of Palm distributions for specific models and some applications....

  13. [Thoughts on the spatial distribution of population].

    Science.gov (United States)

    Borisovna, L; Velez, F

    1991-12-01

    city in all age groups, especially in the 15-19 cohort. A large proportion of the migrants were more highly educated than the average city dweller. The average rate of growth of the working age population in the city was 6% from 1970-80, implying a need for 35,000 new jobs annually. But in 1980-90, only 10,000 new jobs were added each year. The relative importance of tertiary sector employment has increased significantly. A review of the population characteristics and spatial distribution of the city and state of Puebla strongly suggests that decentralization should be vigorously pursued as a means of improving the wellbeing of the population.

  14. Pore shapes, volume distribution and orientations in monodisperse granular assemblies

    OpenAIRE

    Sufian, Adnan; Russell, Adrian R.; Saadatfar, Mohammad; Whittle, Andrew

    2015-01-01

    The complex mechanical behaviour of granular materials is commonly studied by considering the evolving particle contact network. An often overlooked feature is the influence of micro-scale geometric configuration of pores on the macroscopic response. This paper presents a series of tools to quantify the shape, volume distribution and orientation characteristics of the pore space. The proposed approach is compared against data extracted from physical and numerical experiments with monodisperse...

  15. The European Spatial Development Perspective Shaping the Agenda

    NARCIS (Netherlands)

    Faludi, A.K.F.

    2006-01-01

    The fact that they have created the European Union (EU) notwithstanding, Member States are suspicious of, and even hostile to it. This creates a dynamic that is often puzzling, and this is also true for spatial planning. The latter is not a competence of the European Community, but there is the

  16. Spatial population structure of the Neotropical tiger catfish Pseudoplatystoma metaense: skull and otolith shape variation.

    Science.gov (United States)

    Pérez, A; Fabré, N N

    2013-05-01

    Using geometric morphometrics, the skull and otolith of tiger catfish Pseudoplatystoma metaense were analysed to identify population structure in tributaries of the Apure River (i.e. the Sarare, Caparo, Guanare, Portuguesa and San Carlos Rivers) in the Orinoco basin, Venezuela. The analyses show uniformity in skull and otolith shapes of P. metaense within and among four tributaries, with only the Caparo River showing significant differences. Within the Apure basin, the stock of P. metaense was differentiated through spawning, refuge and nursery areas. This study concludes that populations of P. metaense from each major tributary in the Orinoco basin should be considered as part of a metapopulation system for management purposes. Human disturbances in the catchment have directly reduced the spawning areas available to this species, decreased the total biomass and changed the spatial distribution of spawning areas. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

  17. Shape Displays: Spatial Interaction with Dynamic Physical Form.

    Science.gov (United States)

    Leithinger, Daniel; Follmer, Sean; Olwal, Alex; Ishii, Hiroshi

    2015-01-01

    Shape displays are an emerging class of devices that emphasize actuation to enable rich physical interaction, complementing concepts in virtual and augmented reality. The ability to render form introduces new opportunities to touch, grasp, and manipulate dynamic physical content and tangible objects, in both nearby and remote environments. This article presents novel hardware, interaction techniques, and applications, which point to the potential for extending the ways that we traditionally interact with the physical world, empowered by digital computation.

  18. Flight Control Using Distributed Shape-Change Effector Arrays

    Science.gov (United States)

    Raney, David L.; Montgomery, Raymond C.; Green, Lawrence I.; Park, Michael A.

    2000-01-01

    Recent discoveries in material science and fluidics have been used to create a variety of novel effector devices that offer great potential to enable new approaches to aerospace vehicle flight control. Examples include small inflatable blisters, shape-memory alloy diaphragms, and piezoelectric patches that may be used to produce distortions or bumps on the surface of an airfoil to generate control moments. Small jets have also been used to produce a virtual shape-change through fluidic means by creating a recirculation bubble on the surface of an airfoil. An advanced aerospace vehicle might use distributed arrays of hundreds of such devices to generate moments for stabilization and maneuver control, either augmenting or replacing conventional ailerons, flaps or rudders. This research demonstrates the design and use of shape-change device arrays for a tailless aircraft in a low-rate maneuvering application. A methodology for assessing the control authority of the device arrays is described, and a suite of arrays is used in a dynamic simulation to illustrate allocation and deployment methodologies. Although the authority of the preliminary shape-change array designs studied in this paper appeared quite low, the simulation results indicate that the effector suite possessed sufficient authority to stabilize and maneuver the vehicle in mild turbulence.

  19. Shaping the spatial and spectral emissivity at the diffraction limit

    International Nuclear Information System (INIS)

    Makhsiyan, Mathilde; Bouchon, Patrick; Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

    2015-01-01

    Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing

  20. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Science.gov (United States)

    Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

    2015-02-01

    The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  1. Delineating Facies Spatial Distribution by Integrating Ensemble Data Assimilation and Indicator Geostatistics with Level Set Transformation.

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn Edward; Song, Xuehang; Ye, Ming; Dai, Zhenxue; Zachara, John; Chen, Xingyuan

    2017-03-01

    A new approach is developed to delineate the spatial distribution of discrete facies (geological units that have unique distributions of hydraulic, physical, and/or chemical properties) conditioned not only on direct data (measurements directly related to facies properties, e.g., grain size distribution obtained from borehole samples) but also on indirect data (observations indirectly related to facies distribution, e.g., hydraulic head and tracer concentration). Our method integrates for the first time ensemble data assimilation with traditional transition probability-based geostatistics. The concept of level set is introduced to build shape parameterization that allows transformation between discrete facies indicators and continuous random variables. The spatial structure of different facies is simulated by indicator models using conditioning points selected adaptively during the iterative process of data assimilation. To evaluate the new method, a two-dimensional semi-synthetic example is designed to estimate the spatial distribution and permeability of two distinct facies from transient head data induced by pumping tests. The example demonstrates that our new method adequately captures the spatial pattern of facies distribution by imposing spatial continuity through conditioning points. The new method also reproduces the overall response in hydraulic head field with better accuracy compared to data assimilation with no constraints on spatial continuity on facies.

  2. Spatial Damage Distribution over Cube Armoured Roundheads

    DEFF Research Database (Denmark)

    Alonso, Enrique Maciñeira; Burcharth, Hans F.

    2009-01-01

    Different authors have studied and defined the most critical sector of the roundheads with respect to armour stability in order to calculate the mass needed in the units of the armour. This sector has been located between 90° and 135° relative to the orthogonal of the waves. Moreover, from...... provides data on damage distribution over the head obtained in 3D physical model tests with short crested waves at Aalborg University. Furthermore, the factors influencing the distributions are explained....

  3. Inner membrane fusion mediates spatial distribution of axonal mitochondria

    Science.gov (United States)

    Yu, Yiyi; Lee, Hao-Chih; Chen, Kuan-Chieh; Suhan, Joseph; Qiu, Minhua; Ba, Qinle; Yang, Ge

    2016-01-01

    In eukaryotic cells, mitochondria form a dynamic interconnected network to respond to changing needs at different subcellular locations. A fundamental yet unanswered question regarding this network is whether, and if so how, local fusion and fission of individual mitochondria affect their global distribution. To address this question, we developed high-resolution computational image analysis techniques to examine the relations between mitochondrial fusion/fission and spatial distribution within the axon of Drosophila larval neurons. We found that stationary and moving mitochondria underwent fusion and fission regularly but followed different spatial distribution patterns and exhibited different morphology. Disruption of inner membrane fusion by knockdown of dOpa1, Drosophila Optic Atrophy 1, not only increased the spatial density of stationary and moving mitochondria but also changed their spatial distributions and morphology differentially. Knockdown of dOpa1 also impaired axonal transport of mitochondria. But the changed spatial distributions of mitochondria resulted primarily from disruption of inner membrane fusion because knockdown of Milton, a mitochondrial kinesin-1 adapter, caused similar transport velocity impairment but different spatial distributions. Together, our data reveals that stationary mitochondria within the axon interconnect with moving mitochondria through fusion and fission and that local inner membrane fusion between individual mitochondria mediates their global distribution. PMID:26742817

  4. Biodiversity and spatial distribution of Rotifera in a shallow ...

    African Journals Online (AJOL)

    Biodiversity and spatial distribution of Rotifera in a shallow hyperuetrophic tropical Lake (Cameroon). TSH Zebaze, T Njine, N Kemka, D Niyitegeka, M Nola, MS Foto, E Djiukom, G Ajeagah, HJ Dumont ...

  5. Prediction of spatial distribution for some land use allometric ...

    African Journals Online (AJOL)

    Prediction of spatial distribution for some land use allometric characteristics in land use planning models with geostatistic and Geographical Information System (GIS) (Case study: Boein and Miandasht, Isfahan Province, Iran)

  6. Spatial Distribution and Accessibility of Health Facilities in Akwa ...

    African Journals Online (AJOL)

    The attainment of this goal is a function of the spatial pattern of distribution of healthcare facilities and a measure of the degree of accessibility to healthcare services. This paper therefore analyzed the spatial patterns of healthcare facilities in Akwa Ibom State against the philosophy of achieving the MDGs in the health sector ...

  7. Energy density distribution of shaped waves inside scattering media mapped onto a complete set of diffusion modes

    NARCIS (Netherlands)

    Ojambati, Oluwafemi Stephen; Mosk, Allard; Vellekoop, Ivo Micha; Lagendijk, Aart; Vos, Willem L.

    2016-01-01

    We show that the spatial distribution of the energy density of optimally shaped waves inside a scattering medium can be described by considering only a few of the lowest eigenfunctions of the diffusion equation. Taking into account only the fundamental eigenfunction, the total internal energy inside

  8. Shaping the distribution of vertical velocities of antihydrogen in GBAR

    CERN Document Server

    Dufour, G.; Lambrecht, A.; Nesvizhevsky, V.V.; Reynaud, S.; Voronin, A.Yu.

    2014-01-30

    GBAR is a project aiming at measuring the free fall acceleration of gravity for antimatter, namely antihydrogen atoms ($\\overline{\\mathrm{H}}$). Precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution. We propose to use a new method for shaping the distribution of vertical velocities of $\\overline{\\mathrm{H}}$, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing $\\overline{\\mathrm{H}}$ with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk. We estimate statistical and systematic uncertainties, and show that the accuracy for measuring the free fall acceleration $\\overline{g}$ of $\\overline{\\mathrm{H}}$ could be pushed below $10^{-3}$ under realistic experimental conditions.

  9. [Study on a new method for instrumental line shape measurement of spatial heterodyne interference spectrometer].

    Science.gov (United States)

    Xiong, Wei; Shi, Hai-liang; Yu, Neng-hai

    2015-01-01

    Spatial heterodyne spectroscopy(SHS)is a novel method for hyper-spectral analysis, and instrument line shape function is one of the basic performance parameters, which should be precisely characterized. Based on the analysis of the influence factors(apodization, limited angle, abaxial detector element) and special requirement for measuring method and source, the present paper put forward a new method for measuring with tunable monochromatic light source, and designed experimental equipment with tunable laser and integrating sphere eliminating speckle. Selecting typical spectral range within band range for high spectral resolution scanning (0. 1nm step), the energy distribution of spectrum was obtained according to error correction, spectral reconstruction and normalization. In addition, rule curve for FWHM and wavelength was obtained by the full spectral range scanning interferogram. Finally, theoretical spectrum, ILS convolution simulated spectrum (LBL calculated), and measured carbon dioxide absorption spectrum by ground-based experiment are in good agreement. The result shows that the instrument line shape function exhibits high accuracy.

  10. XRD characterisation of nanoparticle size and shape distributions

    International Nuclear Information System (INIS)

    Armstrong, N.; Kalceff, W.; Cline, J.P.; Bonevich, J.

    2004-01-01

    Full text: The form of XRD lines and the extent of their broadening provide useful structural information about the shape, size distribution, and modal characteristics of the nanoparticles comprising the specimen. Also, the defect content of the nanoparticles can be determined, including the type, dislocation density, and stacking faults/twinning. This information is convoluted together and can be grouped into 'size' and 'defect' broadening contributions. Modern X-ray diffraction analysis techniques have concentrated on quantifying the broadening arising from the size and defect contributions, while accounting for overlapping of profiles, instrumental broadening, background scattering and noise components. We report on a combined Bayesian/Maximum Entropy (MaxEnt) technique developed for use in the certification of a NIST Standard Reference Material (SRM) for size-broadened line profiles. The approach used was chosen because of its generality in removing instrumental broadening from the observed line profiles, and its ability to determine not only the average crystallite size, but also the distribution of sizes and the average shape of crystallites. Moverover, this Bayesian/MaxEnt technique is fully quantitative, in that it also determines uncertainties in the crystallite-size distribution and other parameters. Both experimental and numerical simulations of size broadened line-profiles modelled on a range of specimens with spherical and non-spherical morphologies are presented to demonstrate how this information can be retrieved from the line profile data. The sensitivity of the Bayesian/MaxEnt method to determining the size distribution using varying a priori information are emphasised and discussed

  11. Shape, size, and distribution of magnetic particles in Bjurbole chondrules

    Science.gov (United States)

    Nava, David F.

    1994-01-01

    Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

  12. Spatial distribution of gender inequality in Brazil

    OpenAIRE

    Patrícia Verônica Pinheiro Sales Lima; Marina Rocha de Sousa; Ahmad Saeed Khan; Leonardo Andrade Rocha

    2015-01-01

    The purpose of this article was to analyze how gender inequality is distributed all over the Brazil. To that end, it has been built the Multidimensional Gender Inequality Index (MGII), a synthetic index. The main findings underlined that inequality between men and women manifests itself at different degrees in the federal units, but it is determined by a variety of common factors. The asymmetries are observed, mainly, in the political, labor and income dimensions.  El artículo pretende ana...

  13. Spatial distribution of gender inequality in Brazil

    Directory of Open Access Journals (Sweden)

    Patrícia Verônica Pinheiro Sales Lima

    2015-07-01

    Full Text Available The purpose of this article was to analyze how gender inequality is distributed all over the Brazil. To that end, it has been built the Multidimensional Gender Inequality Index (MGII, a synthetic index. The main findings underlined that inequality between men and women manifests itself at different degrees in the federal units, but it is determined by a variety of common factors. The asymmetries are observed, mainly, in the political, labor and income dimensions.

  14. Visual Statistical Learning Works after Binding the Temporal Sequences of Shapes and Spatial Positions

    Directory of Open Access Journals (Sweden)

    Osamu Watanabe

    2011-05-01

    Full Text Available The human visual system can acquire the statistical structures in temporal sequences of object feature changes, such as changes in shape, color, and its combination. Here we investigate whether the statistical learning for spatial position and shape changes operates separately or not. It is known that the visual system processes these two types of information separately; the spatial information is processed in the parietal cortex, whereas object shapes and colors are detected in the temporal pathway, and, after that, we perceive bound information in the two streams. We examined whether the statistical learning operates before or after binding the shape and the spatial information by using the “re-paired triplet” paradigm proposed by Turk-Browne, Isola, Scholl, and Treat (2008. The result showed that observers acquired combined sequences of shape and position changes, but no statistical information in individual sequence was obtained. This finding suggests that the visual statistical learning works after binding the temporal sequences of shapes and spatial structures and would operate in the higher-order visual system; this is consistent with recent ERP (Abla & Okanoya, 2009 and fMRI (Turk-Browne, Scholl, Chun, & Johnson, 2009 studies.

  15. Holographic monitoring of spatial distributions of singlet oxygen in water

    Science.gov (United States)

    Belashov, A. V.; Bel'tyukova, D. M.; Vasyutinskii, O. S.; Petrov, N. V.; Semenova, I. V.; Chupov, A. S.

    2014-12-01

    A method for monitoring spatial distributions of singlet oxygen in biological media has been developed. Singlet oxygen was generated using Radachlorin® photosensitizer, while thermal disturbances caused by nonradiative deactivation of singlet oxygen were detected by the holographic interferometry technique. Processing of interferograms yields temperature maps that characterize the deactivation process and show the distribution of singlet oxygen species.

  16. Factors driving firm's spatial decisions on distribution channel layout

    NARCIS (Netherlands)

    Onstein, A.T.C.; Ektesaby, M.; Rezaei, J.; Tavasszy, L.A.; van Damme, D.A.

    2017-01-01

    Spatial decisions on distribution channel layout involve the layout of the transport and storage system between production and consumption as well as the selection of distribution centre locations. Both are strategic company decisions to meet logistics challenges, i.e. delivering the right product

  17. First contact distributions for spatial patterns: regularity and estimation

    NARCIS (Netherlands)

    Hansen, M.B.; Baddeley, A.J.; Gill, R.D.

    1999-01-01

    For applications in spatial statistics an important property of a random set X in Rk is its rst contact distribution This is the distribution of the distance from a xed point to the nearest point of X where distance is measured using scalar dilations of a xed test set B We show that if B is convex

  18. Juvenile Penaeid Shrimp Density, Spatial Distribution and Size ...

    African Journals Online (AJOL)

    The effects of habitat characteristics (mangrove creek, sandflat, mudflat and seagrass meadow) water salinity, temperature, and depth on the density, spatial distribution and size distribution of juveniles of five commercially important penaied shrimp species (Metapenaus monoceros, M. stebbingi, Fenneropenaeus indicus, ...

  19. Spatial distribution of dust in the shell elliptical NGC 5982

    NARCIS (Netherlands)

    del Burgo, C.; Carter, D.; Sikkema, G.

    Aims. Shells in Ellipticals are peculiar faint sharp edged features that are thought to be formed by galaxy mergers. We determine the shell and dust distributions, and colours of a well-resolved shell and the underlying galaxy in NGC 5982, and compare the spatial distributions of the dust and gas

  20. Non-homogeneous Behaviour of the Spatial Distribution of ...

    Indian Academy of Sciences (India)

    Abstract. In this paper the longitudinal and latitudinal spatial distribu- tion of macrospicules is examined. We found a statistical relationship between the active longitude (determined by sunspot groups) and the lon- gitudinal distribution of macrospicules. This distribution of macrospicules shows an inhomogeneity and ...

  1. An Assessment of the Spatial Distribution of Government Secondary ...

    African Journals Online (AJOL)

    It reveals that the spatial distribution of Government Owned Secondary Schools in Zaria area is very uneven. The paper argues that uneven distribution of Government Owned Secondary education facilities as well as their inadequacy and inefficiency encourage the proliferation of Private Owned Secondary Schools (POSS) ...

  2. Biotic Interactions Shape the Ecological Distributions of Staphylococcus Species.

    Science.gov (United States)

    Kastman, Erik K; Kamelamela, Noelani; Norville, Josh W; Cosetta, Casey M; Dutton, Rachel J; Wolfe, Benjamin E

    2016-10-18

    Many metagenomic sequencing studies have observed the presence of closely related bacterial species or genotypes in the same microbiome. Previous attempts to explain these patterns of microdiversity have focused on the abiotic environment, but few have considered how biotic interactions could drive patterns of microbiome diversity. We dissected the patterns, processes, and mechanisms shaping the ecological distributions of three closely related Staphylococcus species in cheese rind biofilms. Paradoxically, the most abundant species (S. equorum) is the slowest colonizer and weakest competitor based on growth and competition assays in the laboratory. Through in vitro community reconstructions, we determined that biotic interactions with neighboring fungi help resolve this paradox. Species-specific stimulation of the poor competitor by fungi of the genus Scopulariopsis allows S. equorum to dominate communities in vitro as it does in situ Results of comparative genomic and transcriptomic experiments indicate that iron utilization pathways, including a homolog of the S. aureus staphyloferrin B siderophore operon pathway, are potential molecular mechanisms underlying Staphylococcus-Scopulariopsis interactions. Our integrated approach demonstrates that fungi can structure the ecological distributions of closely related bacterial species, and the data highlight the importance of bacterium-fungus interactions in attempts to design and manipulate microbiomes. Decades of culture-based studies and more recent metagenomic studies have demonstrated that bacterial species in agriculture, medicine, industry, and nature are unevenly distributed across time and space. The ecological processes and molecular mechanisms that shape these distributions are not well understood because it is challenging to connect in situ patterns of diversity with mechanistic in vitro studies in the laboratory. Using tractable cheese rind biofilms and a focus on coagulase-negative staphylococcus (CNS

  3. Positional information generated by spatially distributed signaling cascades.

    Directory of Open Access Journals (Sweden)

    Javier Muñoz-García

    2009-03-01

    Full Text Available The temporal and stationary behavior of protein modification cascades has been extensively studied, yet little is known about the spatial aspects of signal propagation. We have previously shown that the spatial separation of opposing enzymes, such as a kinase and a phosphatase, creates signaling activity gradients. Here we show under what conditions signals stall in the space or robustly propagate through spatially distributed signaling cascades. Robust signal propagation results in activity gradients with long plateaus, which abruptly decay at successive spatial locations. We derive an approximate analytical solution that relates the maximal amplitude and propagation length of each activation profile with the cascade level, protein diffusivity, and the ratio of the opposing enzyme activities. The control of the spatial signal propagation appears to be very different from the control of transient temporal responses for spatially homogenous cascades. For spatially distributed cascades where activating and deactivating enzymes operate far from saturation, the ratio of the opposing enzyme activities is shown to be a key parameter controlling signal propagation. The signaling gradients characteristic for robust signal propagation exemplify a pattern formation mechanism that generates precise spatial guidance for multiple cellular processes and conveys information about the cell size to the nucleus.

  4. Spatial distribution of leprosy in Brazil: a literature review

    Directory of Open Access Journals (Sweden)

    Cláuffer Luiz Machado Silva

    Full Text Available Abstract Leprosy remains a public health problem in developing countries. Among communicable diseases, it is one of the leading causes of permanent disability. Brazil had not reached the goal of reducing cases to less than 1 per 10,000 population. This study aimed to analyze the spatial distribution of leprosy cases in Brazil, using a literature review. The search strategy included the LILACS and MEDLINE databases with no language or period restriction. Ecological studies with spatial data analysis were considered as a criterion for the inclusion. We found 38 studies for review after the selection criteria. Among the epidemiological indicators of the disease, the most common was the new case detection rate. Several articles have explored the association between spatial distribution of leprosy and socioeconomic, demographic, and environmental factors. The most common unit of analysis was the municipality. The spatial distribution methods mostly used were: empirical Bayesian method, autocorrelation (Moran’s I index and Kernel estimates. The distribution of leprosy was very heterogeneous, independent of the unit of analysis. There was a decrease in the rate of detection and among under-15-year-olds, but some regions maintained high endemicity during the study period. The distribution and risk of illness were directly related to living conditions of the population. Improved access to health services was associated with increased detection rate in some regions. Spatial analysis seems to be a very useful tool to study leprosy and to guide interventions and surveillance.

  5. Spatial distribution of leprosy in Brazil: a literature review.

    Science.gov (United States)

    Silva, Cláuffer Luiz Machado; Fonseca, Sandra Costa; Kawa, Helia; Palmer, Dayanna de Oliveira Quintanilha

    2017-01-01

    Leprosy remains a public health problem in developing countries. Among communicable diseases, it is one of the leading causes of permanent disability. Brazil had not reached the goal of reducing cases to less than 1 per 10,000 population. This study aimed to analyze the spatial distribution of leprosy cases in Brazil, using a literature review. The search strategy included the LILACS and MEDLINE databases with no language or period restriction. Ecological studies with spatial data analysis were considered as a criterion for the inclusion. We found 38 studies for review after the selection criteria. Among the epidemiological indicators of the disease, the most common was the new case detection rate. Several articles have explored the association between spatial distribution of leprosy and socioeconomic, demographic, and environmental factors. The most common unit of analysis was the municipality. The spatial distribution methods mostly used were: empirical Bayesian method, autocorrelation (Moran's I index) and Kernel estimates. The distribution of leprosy was very heterogeneous, independent of the unit of analysis. There was a decrease in the rate of detection and among under-15-year-olds, but some regions maintained high endemicity during the study period. The distribution and risk of illness were directly related to living conditions of the population. Improved access to health services was associated with increased detection rate in some regions. Spatial analysis seems to be a very useful tool to study leprosy and to guide interventions and surveillance.

  6. Distribution and predictors of wing shape and size variability in three sister species of solitary bees.

    Directory of Open Access Journals (Sweden)

    Simon Dellicour

    Full Text Available Morphological traits can be highly variable over time in a particular geographical area. Different selective pressures shape those traits, which is crucial in evolutionary biology. Among these traits, insect wing morphometry has already been widely used to describe phenotypic variability at the inter-specific level. On the contrary, fewer studies have focused on intra-specific wing morphometric variability. Yet, such investigations are relevant to study potential convergences of variation that could highlight micro-evolutionary processes. The recent sampling and sequencing of three solitary bees of the genus Melitta across their entire species range provides an excellent opportunity to jointly analyse genetic and morphometric variability. In the present study, we first aim to analyse the spatial distribution of the wing shape and centroid size (used as a proxy for body size variability. Secondly, we aim to test different potential predictors of this variability at both the intra- and inter-population levels, which includes genetic variability, but also geographic locations and distances, elevation, annual mean temperature and precipitation. The comparison of spatial distribution of intra-population morphometric diversity does not reveal any convergent pattern between species, thus undermining the assumption of a potential local and selective adaptation at the population level. Regarding intra-specific wing shape differentiation, our results reveal that some tested predictors, such as geographic and genetic distances, are associated with a significant correlation for some species. However, none of these predictors are systematically identified for the three species as an important factor that could explain the intra-specific morphometric variability. As a conclusion, for the three solitary bee species and at the scale of this study, our results clearly tend to discard the assumption of the existence of a common pattern of intra-specific signal

  7. Distribution and predictors of wing shape and size variability in three sister species of solitary bees.

    Science.gov (United States)

    Dellicour, Simon; Gerard, Maxence; Prunier, Jérôme G; Dewulf, Alexandre; Kuhlmann, Michael; Michez, Denis

    2017-01-01

    Morphological traits can be highly variable over time in a particular geographical area. Different selective pressures shape those traits, which is crucial in evolutionary biology. Among these traits, insect wing morphometry has already been widely used to describe phenotypic variability at the inter-specific level. On the contrary, fewer studies have focused on intra-specific wing morphometric variability. Yet, such investigations are relevant to study potential convergences of variation that could highlight micro-evolutionary processes. The recent sampling and sequencing of three solitary bees of the genus Melitta across their entire species range provides an excellent opportunity to jointly analyse genetic and morphometric variability. In the present study, we first aim to analyse the spatial distribution of the wing shape and centroid size (used as a proxy for body size) variability. Secondly, we aim to test different potential predictors of this variability at both the intra- and inter-population levels, which includes genetic variability, but also geographic locations and distances, elevation, annual mean temperature and precipitation. The comparison of spatial distribution of intra-population morphometric diversity does not reveal any convergent pattern between species, thus undermining the assumption of a potential local and selective adaptation at the population level. Regarding intra-specific wing shape differentiation, our results reveal that some tested predictors, such as geographic and genetic distances, are associated with a significant correlation for some species. However, none of these predictors are systematically identified for the three species as an important factor that could explain the intra-specific morphometric variability. As a conclusion, for the three solitary bee species and at the scale of this study, our results clearly tend to discard the assumption of the existence of a common pattern of intra-specific signal/structure within the

  8. A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow

    OpenAIRE

    Proctor, Diana M.; Fukuyama, Julia A.; Loomer, Peter M.; Armitage, Gary C.; Lee, Stacey A.; Davis, Nicole M.; Ryder, Mark I.; Holmes, Susan P.; Relman, David A.

    2018-01-01

    Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ec...

  9. Spatial distribution measured by the modulation transfer function

    International Nuclear Information System (INIS)

    Rossi, P.; Brice, D.K.; Doyle, B.L.

    2003-01-01

    Spatial distributions in ion micro-beam and IBA experimental practice are regularly characterized through the parameters of FWHM and tail area percentage (TF, tail fraction). Linear and stationary transducer theory allows these distributions to be described in the Fourier-dual frequency space, and provides an indirect method to evaluate them through measurement of the modulation transfer function (MTF). We suggest direct measurement of MTF by employing bar pattern grids, similar to those used for calibration of radiological equipment. Assuming spatial distributions of the form exp(-(|αx|) η ), we are able to relate the MTF measurements to the more popular FWHM and TF. This new approach to determine spatial resolution can become a standard for use by the micro-beam community

  10. Spatial distribution of emissions to air – the SPREAD model

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Gyldenkærne, Steen

    to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously......The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmark’s obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long......-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according...

  11. Analysis of the spatial distribution between successive earthquakes

    International Nuclear Information System (INIS)

    Davidsen, Joern; Paczuski, Maya

    2005-01-01

    Spatial distances between subsequent earthquakes in southern California exhibit scale-free statistics, with a critical exponent δ≅0.6, as well as finite size scaling. The statistics are independent of the threshold magnitude as long as the catalog is complete, but depend strongly on the temporal ordering of events, rather than the geometry of the spatial epicenter distribution. Nevertheless, the spatial distance and waiting time between subsequent earthquakes are uncorrelated with each other. These observations contradict the theory of aftershock zone scaling with main shock magnitude

  12. Verifying the Dependence of Fractal Coefficients on Different Spatial Distributions

    International Nuclear Information System (INIS)

    Gospodinov, Dragomir; Marekova, Elisaveta; Marinov, Alexander

    2010-01-01

    A fractal distribution requires that the number of objects larger than a specific size r has a power-law dependence on the size N(r) = C/r D ∝r -D where D is the fractal dimension. Usually the correlation integral is calculated to estimate the correlation fractal dimension of epicentres. A 'box-counting' procedure could also be applied giving the 'capacity' fractal dimension. The fractal dimension can be an integer and then it is equivalent to a Euclidean dimension (it is zero of a point, one of a segment, of a square is two and of a cube is three). In general the fractal dimension is not an integer but a fractional dimension and there comes the origin of the term 'fractal'. The use of a power-law to statistically describe a set of events or phenomena reveals the lack of a characteristic length scale, that is fractal objects are scale invariant. Scaling invariance and chaotic behavior constitute the base of a lot of natural hazards phenomena. Many studies of earthquakes reveal that their occurrence exhibits scale-invariant properties, so the fractal dimension can characterize them. It has first been confirmed that both aftershock rate decay in time and earthquake size distribution follow a power law. Recently many other earthquake distributions have been found to be scale-invariant. The spatial distribution of both regional seismicity and aftershocks show some fractal features. Earthquake spatial distributions are considered fractal, but indirectly. There are two possible models, which result in fractal earthquake distributions. The first model considers that a fractal distribution of faults leads to a fractal distribution of earthquakes, because each earthquake is characteristic of the fault on which it occurs. The second assumes that each fault has a fractal distribution of earthquakes. Observations strongly favour the first hypothesis.The fractal coefficients analysis provides some important advantages in examining earthquake spatial distribution, which are

  13. The effect of spatial light modulator (SLM) dependent dispersion on spatial beam shaping

    CSIR Research Space (South Africa)

    Spangenberg, D-M

    2013-08-01

    Full Text Available . This introduces a phase difference between the different wavelengths of the light thereby causing the different wavelengths to disperse as it propagates through the medium. Spatial dispersion occurs when light with different wavelengths is incident on some mask... SLM and adjusts the wave front of light passing through it by no more than a few wavelengths. The combination of many pixels allows us to generate a mask which causes spatial dispersion to occur. The refractive index of the LC cells of the SLM has a...

  14. Generating shaped femtosecond pulses in the far infrared using a spatial light modulator and difference frequency generation

    CSIR Research Space (South Africa)

    Botha, N

    2010-08-31

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  15. Modelling the spatial shape of nondiffracting beams: Experimental generation of Frozen Waves via computer generated holograms

    OpenAIRE

    Vieira, Tárcio A.; Zamboni-Rached, Michel; Gesualdi, Marcos R. R.

    2013-01-01

    In this paper we implement experimentally the spatial shape modelling of nondiffracting optical beams via computer generated holograms. The results reported here are the experimental confirmation of the so called Frozen Wave method, developed few years ago. Optical beams of this type can possess potential applications in optical tweezers, medicine, atom guiding, remote sensing, etc..

  16. The spatial structure of stimuli shapes the timescale of correlations in population spiking activity.

    Directory of Open Access Journals (Sweden)

    Ashok Litwin-Kumar

    Full Text Available Throughout the central nervous system, the timescale over which pairs of neural spike trains are correlated is shaped by stimulus structure and behavioral context. Such shaping is thought to underlie important changes in the neural code, but the neural circuitry responsible is largely unknown. In this study, we investigate a stimulus-induced shaping of pairwise spike train correlations in the electrosensory system of weakly electric fish. Simultaneous single unit recordings of principal electrosensory cells show that an increase in the spatial extent of stimuli increases correlations at short (≈ 10 ms timescales while simultaneously reducing correlations at long (≈ 100 ms timescales. A spiking network model of the first two stages of electrosensory processing replicates this correlation shaping, under the assumptions that spatially broad stimuli both saturate feedforward afferent input and recruit an open-loop inhibitory feedback pathway. Our model predictions are experimentally verified using both the natural heterogeneity of the electrosensory system and pharmacological blockade of descending feedback projections. For weak stimuli, linear response analysis of the spiking network shows that the reduction of long timescale correlation for spatially broad stimuli is similar to correlation cancellation mechanisms previously suggested to be operative in mammalian cortex. The mechanism for correlation shaping supports population-level filtering of irrelevant distractor stimuli, thereby enhancing the population response to relevant prey and conspecific communication inputs.

  17. Spatial distribution of emissions to air - the SPREAD model

    Energy Technology Data Exchange (ETDEWEB)

    Plejdrup, M.S.; Gyldenkaerne, S.

    2011-04-15

    The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmark's obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously, a distribution on the 17x17 km EMEP grid has been set up and used in research projects combined with detailed distributions for a few sectors or sub-sectors e.g. a distribution for emissions from road traffic on 1x1 km resolution. SPREAD is developed to generate improved spatial emission data for e.g. air quality modelling in exposure studies. SPREAD includes emission distributions for each sector in the Danish inventory system; stationary combustion, mobile sources, fugitive emissions from fuels, industrial processes, solvents and other product use, agriculture and waste. This model enables generation of distributions for single sectors and for a number of sub-sectors and single sources as well. This report documents the methodologies in this first version of SPREAD and presents selected results. Further, a number of potential improvements for later versions of SPREAD are addressed and discussed. (Author)

  18. Mechanical Motion Induced by Spatially Distributed Limit-Cycle Oscillators

    Science.gov (United States)

    Sakaguchi, Hidetsugu; Mukae, Yuuki

    2017-03-01

    Spatially distributed limited-cycle oscillators are seen in various physical and biological systems. In internal organs, mechanical motions are induced by the stimuli of spatially distributed limit-cycle oscillators. We study several mechanical motions by limit-cycle oscillators using simple model equations. One problem is deformation waves of radius oscillation induced by desynchronized limit-cycle oscillators, which is motivated by peristaltic motion of the small intestine. A resonance-like phenomenon is found in the deformation waves, and particles can be transported by the deformation waves. Another is the beating motion of the heart. The expansion and contraction motion is realized by a spatially synchronized limit-cycle oscillation; however, the strong beating disappears by spiral chaos, which is closely related to serious arrhythmia in the heart.

  19. Spatial distribution of Nemesis lamna Risso 1826 (Copepoda ...

    African Journals Online (AJOL)

    The selection of a specific site of attachment by a copepod parasite is determined by a set of mostly unknown factors. The spatial distribution of Nemesis lamna on the gill filaments of white sharks Carcharodon carcharias was investigated. The complete set of left gills of 11 hosts was examined and the location, orientation ...

  20. Composition and spatial distribution of cephalopods in two North ...

    African Journals Online (AJOL)

    The faunistic composition and the spatial distribution of the cephalopod fauna were studied and compared in two areas of the north-western Mediterranean: the Catalan Sea (Spanish coast) and the northern Tyrrhenian Sea (Italian coast). In all, 46 species were collected in the Catalan Sea and 36 in the northern Tyrrhenian ...

  1. Spatial distribution of glycerophospholipids in the ocular lens.

    Directory of Open Access Journals (Sweden)

    Jaroslav Pól

    Full Text Available Knowledge of the spatial distribution of lipids in the intraocular lens is important for understanding the physiology and biochemistry of this unique tissue and for gaining a better insight into the mechanisms underlying diseases of the lens. Following our previous study showing the spatial distribution of sphingolipids in the porcine lens, the current study used ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS to provide the whole lipidome of porcine lens and these studies were supplemented by matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI of the lens using ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS to determine the spatial distribution of glycerophospholipids. Altogether 172 lipid species were identified with high confidence and their concentration was determined. Sphingomyelins, phosphatidylcholines, and phosphatidylethanolamines were the most abundant lipid classes. We then determined the spatial and concentration-dependent distributions of 20 phosphatidylcholines, 6 phosphatidylethanolamines, and 4 phosphatidic acids. Based on the planar molecular images of the lipids, we report the organization of fiber cell membranes within the ocular lens and suggest roles for these lipids in normal and diseased lenses.

  2. A preliminary survey and analysis of the spatial distribution of ...

    African Journals Online (AJOL)

    The spatial distribution of aquatic macroinvertebrates in the Okavango River Delta, Botswana, was investigated during the lowwater period in February 2003. This complements an earlier study undertaken during high-water in June 2000. Seventy-five samples were taken in a range of aquatic habitats at 29 georeference ...

  3. Spatial distribution and habitat characterisation of mosquito species ...

    African Journals Online (AJOL)

    Background: Infections with mosquito-borne parasites are common in human populations inhabiting tropical regions of the world. Malaria is endemic along Kenyan Lake Victoria basin and its vectors are fresh water breeders. However, much less is known about the current spatial distribution and habitat characterisation of ...

  4. Modelling the spatial distribution of linear landscape elements in Europe

    NARCIS (Netherlands)

    Zanden, van der E.H.; Verburg, P.H.; Mücher, C.A.

    2013-01-01

    Linear landscape elements, such as ditches, hedgerows, lines of trees and field margins, provide important habitats and ecosystem services and function as ecological infrastructure for species within agricultural landscapes. Spatial maps of the distribution of these elements are needed to better

  5. Spatial Distribution of Micro Finance Institutions and Agricultural ...

    African Journals Online (AJOL)

    This study examines the impact of spatial distribution of Micro-finance institutions on Agricultural development in Ekiti State, Nigeria. Agriculture is an engine for economic growth in developing countries and rural microfinance is also critical to that growth. Data for this study were collected through primary sources.

  6. Spatial distribution of saline water and possible sources of intrusion ...

    African Journals Online (AJOL)

    user

    The spatial distribution of saline water and possible sources of intrusion into Lekki lagoon and transitional effects on the lacustrine ichthyofaunal characteristics were studied during March, 2006 and. February, 2008. The water quality analysis indicated that, salinity has drastically increased recently in the lagoon (0.007 to ...

  7. Quantitative evaluation of legacy phosphorus and its spatial distribution.

    Science.gov (United States)

    Lou, Hezhen; Zhao, Changsen; Yang, Shengtian; Shi, Liuhua; Wang, Yue; Ren, Xiaoyu; Bai, Juan

    2018-04-01

    A phosphorus resource crisis threatens the security of global crop production, especially in developing countries like China and Brazil. Legacy phosphorus (legacy-P), which is left behind in agricultural soil by over-fertilization, can help address this issue as a new resource in the soil phosphorus pool. However, issues involved with calculating and defining the spatial distribution of legacy-P hinder its future utilization. To resolve these issues, this study applied remote sensing and ecohydrological modeling to precisely quantify legacy-P and define its spatial distribution in China's Sanjiang Plain from 2000 to 2014. The total legacy-P in the study area was calculated as 579,090 t with an annual average of 38,600 t; this comprises 51.83% of the phosphorus fertilizer applied annually. From 2000 to 2014, the annual amount of legacy-P increased by more than 3.42-fold, equivalent to a 2460-ton increase each year. The spatial distribution of legacy-P showed heterogeneity and agglomeration in this area, with peaks in cultivated land experiencing long-term agricultural development. This study supplies a new approach to finding legacy-P in soil as a precondition for future utilization. Once its spatial distribution is known, legacy-P can be better utilized in agriculture to help alleviate the phosphorus resource crisis. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Spatial distribution of potential and positive Aedes aegypti breeding sites

    Directory of Open Access Journals (Sweden)

    Daniel Elías Cuartas

    2017-03-01

    Conclusions: The spatial relationship between positive and potential A. aegypti breeding sites both indoors and outdoors is dynamic and highly sensitive to the characteristics of each territory. Knowing how positive and potential breeding sites are distributed contributes to the prioritization of resources and actions in vector control programs.

  9. Spatial distribution of saline water and possible sources of intrusion ...

    African Journals Online (AJOL)

    The spatial distribution of saline water and possible sources of intrusion into Lekki lagoon and transitional effects on the lacustrine ichthyofaunal characteristics were studied during March, 2006 and February, 2008. The water quality analysis indicated that, salinity has drastically increased recently in the lagoon (0.007 to ...

  10. Influence of shade systems on spatial distribution and infestation of ...

    African Journals Online (AJOL)

    ACSS

    3. Spatial distribution and infestation of the Black Coffee Twig Borer on coffee proximal to the stem), middle and tip. (upper 3rd portion distal to the stem) sections. Number of X. compactus entry holes in each section was then determined after which, they were dissected near the entry holes and the direction of X. compactus ...

  11. The effect of spatial planning patterns on distribution of pedestrians ...

    African Journals Online (AJOL)

    Abstract. This study focuses on public spaces of residential neighbourhoods in the City of Nairobi. It establishes various spatial characteristics, hence patterns, that have a bearing on the distribution of pedestrians therein. A higher encounter rate of pedestrians is a desirable public space quality given that the higher degree ...

  12. Spatial and Temporal Distribution of Reef Fish Spawning ...

    African Journals Online (AJOL)

    The spatial patterns among fish families were attributed to a combination of differences in species abundance and distribution as well as variation in fishing effort. Spawning periodicity reported by fishers indicated that for snappers and rabbitfishes, the most activity occurred across a protracted period of October to April/May, ...

  13. Examining the Spatial Distribution of Marijuana Establishments in Colorado

    Science.gov (United States)

    Kerski, Joseph

    2018-01-01

    In this 22-question activity, high school students investigate the spatial distribution of marijuana stores in Colorado using an interactive web map containing stores, centers, highways, population, and other data at several scales. After completing this lesson, students will know and be able to: (1) Use interactive maps, layers, and tools in…

  14. Development of Spatial Distribution Patterns by Biofilm Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Hansen, Susse Kirkelund; Bak Christensen, Bjarke

    2015-01-01

    Confined spatial patterns of microbial distribution are prevalent in nature, such as in microbial mats, soil communities, and water stream biofilms. The symbiotic two-species consortium of Pseudomonas putida and Acinetobacter sp. C6, originally isolated from a creosote-polluted aquifer, has evolved...

  15. Investigation of Spatial Distribution Properties of Mid-Infrared ...

    African Journals Online (AJOL)

    The spatial distribution properties of quantum cascade lasers with emission wavelengths around 7 µm were measured. In addition, the emission profile on a plane orthogonal to the propagation axis of the beam were measured and the full width at half maximum (FWHM) on the orthogonal and lateral directions calculated.

  16. Spatial distribution of atmospheric carbon monoxide over Bay of ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 117; Issue 4. Spatial distribution of atmospheric carbon monoxide over Bay of Bengal and Arabian Sea: Measurements during pre-monsoon period of 2006. V R Aneesh G Mohankumar S Sampath. Volume 117 Issue 4 August 2008 pp 449-455 ...

  17. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Directory of Open Access Journals (Sweden)

    Jared Maxson

    2015-02-01

    Full Text Available The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  18. Fractal nature of hydrocarbon deposits. 2. Spatial distribution

    International Nuclear Information System (INIS)

    Barton, C.C.; Schutter, T.A; Herring, P.R.; Thomas, W.J.; Scholz, C.H.

    1991-01-01

    Hydrocarbons are unevenly distributed within reservoirs and are found in patches whose size distribution is a fractal over a wide range of scales. The spatial distribution of the patches is also fractal and this can be used to constrain the design of drilling strategies also defined by a fractal dimension. Fractal distributions are scale independent and are characterized by a power-law scaling exponent termed the fractal dimension. The authors have performed fractal analyses on the spatial distribution of producing and showing wells combined and of dry wells in 1,600-mi 2 portions of the Denver and Powder River basins that were nearly completely drilled on quarter-mile square-grid spacings. They have limited their analyses to wells drilled to single stratigraphic intervals so that the map pattern revealed by drilling is representative of the spatial patchiness of hydrocarbons at depth. The fractal dimensions for the spatial patchiness of hydrocarbons in the two basins are 1.5 and 1.4, respectively. The fractal dimension for the pattern of all wells drilled is 1.8 for both basins, which suggests a drilling strategy with a fractal dimension significantly higher than the dimensions 1.5 and 1.4 sufficient to efficiently and economically explore these reservoirs. In fact, the fractal analysis reveals that the drilling strategy used in these basins approaches a fractal dimension of 2.0, which is equivalent to random drilling with no geologic input. Knowledge of the fractal dimension of a reservoir prior to drilling would provide a basis for selecting and a criterion for halting a drilling strategy for exploration whose fractal dimension closely matches that of the spatial fractal dimension of the reservoir, such a strategy should prove more efficient and economical than current practice

  19. Spatial distribution of angular momentum inside the nucleon

    Science.gov (United States)

    Lorcé, Cédric; Mantovani, Luca; Pasquini, Barbara

    2018-01-01

    We discuss in detail the spatial distribution of angular momentum inside the nucleon. We show that the discrepancies between different definitions originate from terms that integrate to zero. Even though these terms can safely be dropped at the integrated level, they have to be taken into account when discussing distributions. Using the scalar diquark model, we illustrate our results and, for the first time, check explicitly that the equivalence between kinetic and canonical orbital angular momentum persists at the level of distributions, as expected in a system without gauge degrees of freedom.

  20. Spatial distribution sampling and Monte Carlo simulation of radioactive isotopes

    CERN Document Server

    Krainer, Alexander Michael

    2015-01-01

    This work focuses on the implementation of a program for random sampling of uniformly spatially distributed isotopes for Monte Carlo particle simulations and in specific FLUKA. With FLUKA it is possible to calculate the radio nuclide production in high energy fields. The decay of these nuclide, and therefore the resulting radiation field, however can only be simulated in the same geometry. This works gives the tool to simulate the decay of the produced nuclide in other geometries. With that the radiation field from an irradiated object can be simulated in arbitrary environments. The sampling of isotope mixtures was tested by simulating a 50/50 mixture of $Cs^{137}$ and $Co^{60}$. These isotopes are both well known and provide therefore a first reliable benchmark in that respect. The sampling of uniformly distributed coordinates was tested using the histogram test for various spatial distributions. The advantages and disadvantages of the program compared to standard methods are demonstrated in the real life ca...

  1. Inputs and spatial distribution patterns of Cr in Jiaozhou Bay

    Science.gov (United States)

    Yang, Dongfang; Miao, Zhenqing; Huang, Xinmin; Wei, Linzhen; Feng, Ming

    2018-03-01

    Cr pollution in marine bays has been one of the critical environmental issues, and understanding the input and spatial distribution patterns is essential to pollution control. In according to the source strengths of the major pollution sources, the input patterns of pollutants to marine bay include slight, moderate and heavy, and the spatial distribution are corresponding to three block models respectively. This paper analyzed input patterns and distributions of Cr in Jiaozhou Bay, eastern China based on investigation on Cr in surface waters during 1979-1983. Results showed that the input strengths of Cr in Jiaozhou Bay could be classified as moderate input and slight input, and the input strengths were 32.32-112.30 μg L-1 and 4.17-19.76 μg L-1, respectively. The input patterns of Cr included two patterns of moderate input and slight input, and the horizontal distributions could be defined by means of Block Model 2 and Block Model 3, respectively. In case of moderate input pattern via overland runoff, Cr contents were decreasing from the estuaries to the bay mouth, and the distribution pattern was parallel. In case of moderate input pattern via marine current, Cr contents were decreasing from the bay mouth to the bay, and the distribution pattern was parallel to circular. The Block Models were able to reveal the transferring process of various pollutants, and were helpful to understand the distributions of pollutants in marine bay.

  2. Shapes of reaction-time distributions and shapes of learning curves: a test of the instance theory of automaticity.

    Science.gov (United States)

    Logan, G D

    1992-09-01

    The instance theory assumes that automatic performance is based on single-step direct-access retrieval from memory of prior solutions to present problems. The theory predicts that the shape of the learning curve depends on the shape of the distribution of retrieval times. One can deduce from the fundamental assumptions of the theory that (1) the entire distribution of reaction times, not just the mean, will decrease as a power function of practice; (2) asymptotically, the retrieval-time distribution must be a Weibull distribution; and (3) the exponent of the Weibull, which is the parameter that determines its shape, must be the reciprocal of the exponent of the power function. These predictions were tested and mostly confirmed in 12 data sets from 2 experiments. The ability of the instance theory to predict the power law is contrasted with the ability of other theories to account for it.

  3. Modelling the Spatial Distribution of Wind Energy Resources in Latvia

    Science.gov (United States)

    Aniskevich, S.; Bezrukovs, V.; Zandovskis, U.; Bezrukovs, D.

    2017-12-01

    The paper studies spatial wind energy flow distribution in Latvia based on wind speed measurements carried out at an altitude of 10 m over a period of two years, from 2015 to 2016. The measurements, with 1 min increments, were carried out using certified measuring instruments installed at 22 observation stations of the Latvian National Hydrometeorological and Climatological Service of the Latvian Environment, Geology and Meteorology Centre (LEGMC). The models of the spatial distribution of averaged wind speed and wind energy density were developed using the method of spatial interpolation based on the historical measurement results and presented in the form of colour contour maps with a 1×1 km resolution. The paper also provides the results of wind speed spatial distribution modelling using a climatological reanalysis ERA5 at the altitudes of 10, 54, 100 and 136 m with a 31×31 km resolution. The analysis includes the comparison of actual wind speed measurement results with the outcomes of ERA5 modelling for meteorological observation stations in Ainazi, Daugavpils, Priekuli, Saldus and Ventspils.

  4. Interference competition as a key determinant for spatial distribution of mangrove crabs

    KAUST Repository

    Cannicci, Stefano

    2018-02-15

    The spatial distribution of mangrove crabs has been commonly associated with tree zonation and abiotic factors such as ground temperature and soil granulometry. Conversely, no studies were designed to investigate the role of competition for resources and predation in shaping crab distribution in mangroves, despite these biotic factors are recognised as key determinants for spatial patterns observed in the communities colonising rocky and sandy intertidal habitats.We studied floral and faunal assemblages in two zones of a Sri Lankan mangrove, a man-made upper intertidal level and a natural eulittoral, mid-shore one. Leaf choice experiments were designed to study both feeding rate and intra and inter-specific interactions for food of sesarmid crabs in the two habitats in order to better understand crab spatial distribution.The two intertidal belts differed in terms of floral composition and crab species abundance. The eulittoral zone was strongly dominated by Neosarmatium smithi, while within the elevated littoral fringe four sesarmids (N. smithi, N. asiaticum, N. malabaricum and Muradium tetragonum) were more evenly distributed. At both levels, all sesarmids showed to collect significantly more Bruguiera spp. and Rhizophora apiculata leaves than Excoecaria agallocha ones. There was no temporal segregation in feeding activity among the four species, resulting in a high interference competition for leaves. Regardless of the habitat, N. smithi was always successful in winning inter-specific fights.Our results showed that the elevated littoral fringe was more crowded with crabs, but was less favourable in terms of food availability and environmental conditions. The dominance of N. smithi in gathering mangrove leaves suggests that this species may segregate the other sesarmids into less favourable habitats. The present data strongly suggest for the first time that interference competition for food can contribute to shape mangrove crab spatial distribution.

  5. Differentiating gold nanorod samples using particle size and shape distributions from transmission electron microscope images

    Science.gov (United States)

    Grulke, Eric A.; Wu, Xiaochun; Ji, Yinglu; Buhr, Egbert; Yamamoto, Kazuhiro; Song, Nam Woong; Stefaniak, Aleksandr B.; Schwegler-Berry, Diane; Burchett, Woodrow W.; Lambert, Joshua; Stromberg, Arnold J.

    2018-04-01

    Size and shape distributions of gold nanorod samples are critical to their physico-chemical properties, especially their longitudinal surface plasmon resonance. This interlaboratory comparison study developed methods for measuring and evaluating size and shape distributions for gold nanorod samples using transmission electron microscopy (TEM) images. The objective was to determine whether two different samples, which had different performance attributes in their application, were different with respect to their size and/or shape descriptor distributions. Touching particles in the captured images were identified using a ruggedness shape descriptor. Nanorods could be distinguished from nanocubes using an elongational shape descriptor. A non-parametric statistical test showed that cumulative distributions of an elongational shape descriptor, that is, the aspect ratio, were statistically different between the two samples for all laboratories. While the scale parameters of size and shape distributions were similar for both samples, the width parameters of size and shape distributions were statistically different. This protocol fulfills an important need for a standardized approach to measure gold nanorod size and shape distributions for applications in which quantitative measurements and comparisons are important. Furthermore, the validated protocol workflow can be automated, thus providing consistent and rapid measurements of nanorod size and shape distributions for researchers, regulatory agencies, and industry.

  6. Spatially Explicit Modeling Reveals Cephalopod Distributions Match Contrasting Trophic Pathways in the Western Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Patricia Puerta

    Full Text Available Populations of the same species can experience different responses to the environment throughout their distributional range as a result of spatial and temporal heterogeneity in habitat conditions. This highlights the importance of understanding the processes governing species distribution at local scales. However, research on species distribution often averages environmental covariates across large geographic areas, missing variability in population-environment interactions within geographically distinct regions. We used spatially explicit models to identify interactions between species and environmental, including chlorophyll a (Chla and sea surface temperature (SST, and trophic (prey density conditions, along with processes governing the distribution of two cephalopods with contrasting life-histories (octopus and squid across the western Mediterranean Sea. This approach is relevant for cephalopods, since their population dynamics are especially sensitive to variations in habitat conditions and rarely stable in abundance and location. The regional distributions of the two cephalopod species matched two different trophic pathways present in the western Mediterranean Sea, associated with the Gulf of Lion upwelling and the Ebro river discharges respectively. The effects of the studied environmental and trophic conditions were spatially variant in both species, with usually stronger effects along their distributional boundaries. We identify areas where prey availability limited the abundance of cephalopod populations as well as contrasting effects of temperature in the warmest regions. Despite distributional patterns matching productive areas, a general negative effect of Chla on cephalopod densities suggests that competition pressure is common in the study area. Additionally, results highlight the importance of trophic interactions, beyond other common environmental factors, in shaping the distribution of cephalopod populations. Our study presents

  7. Scaling precipitation input to spatially distributed hydrological models by measured snow distribution

    Directory of Open Access Journals (Sweden)

    Christian Vögeli

    2016-12-01

    Full Text Available Accurate knowledge on snow distribution in alpine terrain is crucial for various applicationssuch as flood risk assessment, avalanche warning or managing water supply and hydro-power.To simulate the seasonal snow cover development in alpine terrain, the spatially distributed,physics-based model Alpine3D is suitable. The model is typically driven by spatial interpolationsof observations from automatic weather stations (AWS, leading to errors in the spatial distributionof atmospheric forcing. With recent advances in remote sensing techniques, maps of snowdepth can be acquired with high spatial resolution and accuracy. In this work, maps of the snowdepth distribution, calculated from summer and winter digital surface models based on AirborneDigital Sensors (ADS, are used to scale precipitation input data, with the aim to improve theaccuracy of simulation of the spatial distribution of snow with Alpine3D. A simple method toscale and redistribute precipitation is presented and the performance is analysed. The scalingmethod is only applied if it is snowing. For rainfall the precipitation is distributed by interpolation,with a simple air temperature threshold used for the determination of the precipitation phase.It was found that the accuracy of spatial snow distribution could be improved significantly forthe simulated domain. The standard deviation of absolute snow depth error is reduced up toa factor 3.4 to less than 20 cm. The mean absolute error in snow distribution was reducedwhen using representative input sources for the simulation domain. For inter-annual scaling, themodel performance could also be improved, even when using a remote sensing dataset from adifferent winter. In conclusion, using remote sensing data to process precipitation input, complexprocesses such as preferential snow deposition and snow relocation due to wind or avalanches,can be substituted and modelling performance of spatial snow distribution is improved.

  8. Managing distributed dynamic systems with spatial grasp technology

    CERN Document Server

    Sapaty, Peter Simon

    2017-01-01

    The book describes a novel ideology and supporting information technology for integral management of both civil and defence-orientated large, distributed dynamic systems. The approach is based on a high-level Spatial Grasp Language, SGL, expressing solutions in physical, virtual, executive and combined environments in the form of active self-evolving and self-propagating patterns spatially matching the systems to be created, modified and controlled. The communicating interpreters of SGL can be installed in key system points, which may be in large numbers (up to millions and billions) and represent equipped humans, robots, laptops, smartphones, smart sensors, etc. Operating under gestalt-inspired scenarios in SGL initially injected from any points, these systems can be effectively converted into goal-driven spatial machines (rather than computers as dealing with physical matter too) capable of responding to numerous challenges caused by growing world dynamics in the 21st century. Including numerous practical e...

  9. Spatial distribution of excitatory synapses on the dendrites of ganglion cells in the mouse retina.

    Directory of Open Access Journals (Sweden)

    Yin-Peng Chen

    Full Text Available Excitatory glutamatergic inputs from bipolar cells affect the physiological properties of ganglion cells in the mammalian retina. The spatial distribution of these excitatory synapses on the dendrites of retinal ganglion cells thus may shape their distinct functions. To visualize the spatial pattern of excitatory glutamatergic input into the ganglion cells in the mouse retina, particle-mediated gene transfer of plasmids expressing postsynaptic density 95-green fluorescent fusion protein (PSD95-GFP was used to label the excitatory synapses. Despite wide variation in the size and morphology of the retinal ganglion cells, the expression of PSD95 puncta was found to follow two general rules. Firstly, the PSD95 puncta are regularly spaced, at 1-2 µm intervals, along the dendrites, whereby the presence of an excitatory synapse creates an exclusion zone that rules out the presence of other glutamatergic synaptic inputs. Secondly, the spatial distribution of PSD95 puncta on the dendrites of diverse retinal ganglion cells are similar in that the number of excitatory synapses appears to be less on primary dendrites and to increase to a plateau on higher branch order dendrites. These observations suggest that synaptogenesis is spatially regulated along the dendritic segments and that the number of synaptic contacts is relatively constant beyond the primary dendrites. Interestingly, we also found that the linear puncta density is slightly higher in large cells than in small cells. This may suggest that retinal ganglion cells with a large dendritic field tend to show an increased connectivity of excitatory synapses that makes up for their reduced dendrite density. Mapping the spatial distribution pattern of the excitatory synapses on retinal ganglion cells thus provides explicit structural information that is essential for our understanding of how excitatory glutamatergic inputs shape neuronal responses.

  10. Spatial distribution of enzyme activities in the rhizosphere

    Science.gov (United States)

    Razavi, Bahar S.; Zarebanadkouki, Mohsen; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2015-04-01

    The rhizosphere, the tiny zone of soil surrounding roots, certainly represents one of the most dynamic habitat and interfaces on Earth. Activities of enzymes produced by both plant roots and microbes are the primary biological drivers of organic matter decomposition and nutrient cycling. That is why there is an urgent need in spatially explicit methods for the determination of the rhizosphere extension and enzyme distribution. Recently, zymography as a new technique based on diffusion of enzymes through the 1 mm gel plate for analysis has been introduced (Spohn & Kuzyakov, 2013). We developed the zymography technique to visualize the enzyme activities with a higher spatial resolution. For the first time, we aimed at quantitative imaging of enzyme activities as a function of distance from the root tip and the root surface in the soil. We visualized the two dimensional distribution of the activity of three enzymes: β-glucosidase, phosphatase and leucine amino peptidase in the rhizosphere of maize using fluorogenically labelled substrates. Spatial-resolution of fluorescent images was improved by direct application of a substrate saturated membrane to the soil-root system. The newly-developed direct zymography visualized heterogeneity of enzyme activities along the roots. The activity of all enzymes was the highest at the apical parts of individual roots. Across the roots, the enzyme activities were higher at immediate vicinity of the roots (1.5 mm) and gradually decreased towards the bulk soil. Spatial patterns of enzyme activities as a function of distance from the root surface were enzyme specific, with highest extension for phosphatase. We conclude that improved zymography is promising in situ technique to analyze, visualize and quantify spatial distribution of enzyme activities in the rhizosphere hotspots. References Spohn, M., Kuzyakov, Y., 2013. Phosphorus mineralization can be driven by microbial need for carbon. Soil Biology & Biochemistry 61: 69-75

  11. Evaluation of an Empirical Reservoir Shape Function to Define Sediment Distributions in Small Reservoirs

    Directory of Open Access Journals (Sweden)

    Bogusław Michalec

    2015-08-01

    Full Text Available Understanding and defining the spatial distribution of sediment deposited in reservoirs is essential not only at the design stage but also during the operation. The majority of research concerns the distribution of sediment deposition in medium and large water reservoirs. Most empirical methods do not provide satisfactory results when applied to the determination of sediment deposition in small reservoirs. Small reservoir’s volumes do not exceed 5 × 106 m3 and their capacity-inflow ratio is less than 10%. Long-term silting measurements of three small reservoirs were used to evaluate the method described by Rahmanian and Banihashemi for predicting sediment distributions in small reservoirs. Rahmanian and Banihashemi stated that their model of distribution of sediment deposition in water reservoir works well for a long duration operation. In the presented study, the silting rate was used in order to determine the long duration operation. Silting rate is a quotient of volume of the sediment deposited in the reservoir and its original volume. It was stated that when the silting rate had reached 50%, the sediment deposition in the reservoir may be described by an empirical reservoir depth shape function (RDSF.

  12. Environmental DNA reflects spatial and temporal jellyfish distribution

    OpenAIRE

    Minamoto, Toshifumi; Fukuda, Miho; Katsuhara, Koki R.; Fujiwara, Ayaka; Hidaka, Shunsuke; Yamamoto, Satoshi; Takahashi, Kohji; Masuda, Reiji

    2017-01-01

    Recent development of environmental DNA (eDNA) analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica) as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentration...

  13. LEACHED SOILS IN SLOVENIA: PEDOLOGICAL PROPERTIES, SPATIAL DISTRIBUTION AND CLASSIFICATION

    OpenAIRE

    Rok TURNIŠKI; Helena GRČMAN

    2018-01-01

    Eluvial-illuvial processes plays key role in pedogenesis, especially in the development of leached soils. As reported in Slovenian soil map 1 : 25.000 leached soils cover 2,3 % of Slovenian territory. They occur on different parent materials, mostly on flat relief preserved from erosion and colluvial processes. The aim of our study is the evaluation of their morpohological, physical and chemical properties, spatial distribution and dependency on soil forming factors, especially on parent mate...

  14. Spatial and temporal patterns of global onshore wind speed distribution

    International Nuclear Information System (INIS)

    Zhou, Yuyu; Smith, Steven J

    2013-01-01

    Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind parameters as fitted to a Weibull density function using NCEP/climate forecast system reanalysis (CFSR) data over land areas. The Weibull distribution performs well in fitting the time series wind speed data at most locations according to R 2 , root mean square error, and power density error. The wind speed frequency distribution, as represented by the Weibull k parameter, exhibits a large amount of spatial variation, a regionally varying amount of seasonal variation, and relatively low decadal variation. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull parameter across large regions can result in non-negligible errors. While large-scale wind speed data are often presented in the form of mean wind speeds, these results highlight the need to also provide information on the wind speed frequency distribution. (letter)

  15. LUMINOUS SATELLITES OF EARLY-TYPE GALAXIES. I. SPATIAL DISTRIBUTION

    International Nuclear Information System (INIS)

    Nierenberg, A. M.; Auger, M. W.; Treu, T.; Marshall, P. J.; Fassnacht, C. D.

    2011-01-01

    We study the spatial distribution of faint satellites of intermediate redshift (0.1 s = 1.7 +0.9 -0.8 ) that is comparable to the number of Milky Way satellites with similar host-satellite contrast. The average projected radial profile of the satellite distribution is isothermal (γ p = -1.0 +0.3 -0.4 ), which is consistent with the observed central mass density profile of massive early-type galaxies. Furthermore, the satellite distribution is highly anisotropic (isotropy is ruled out at a >99.99% confidence level). Defining φ to be the offset between the major axis of the satellite spatial distribution and the major axis of the host light profile, we find a maximum posterior probability of φ = 0 and |φ| less than 42 0 at the 68% confidence level. The alignment of the satellite distribution with the light of the host is consistent with simulations, assuming that light traces mass for the host galaxy as observed for lens galaxies. The anisotropy of the satellite population enhances its ability to produce the flux ratio anomalies observed in gravitationally lensed quasars.

  16. Spatial distribution of enzyme driven reactions at micro-scales

    Science.gov (United States)

    Kandeler, Ellen; Boeddinghaus, Runa; Nassal, Dinah; Preusser, Sebastian; Marhan, Sven; Poll, Christian

    2017-04-01

    Studies of microbial biogeography can often provide key insights into the physiologies, environmental tolerances, and ecological strategies of soil microorganisms that dominate in natural environments. In comparison with aquatic systems, soils are particularly heterogeneous. Soil heterogeneity results from the interaction of a hierarchical series of interrelated variables that fluctuate at many different spatial and temporal scales. Whereas spatial dependence of chemical and physical soil properties is well known at scales ranging from decimetres to several hundred metres, the spatial structure of soil enzymes is less clear. Previous work has primarily focused on spatial heterogeneity at a single analytical scale using the distribution of individual cells, specific types of organisms or collective parameters such as bacterial abundance or total microbial biomass. There are fewer studies that have considered variations in community function and soil enzyme activities. This presentation will give an overview about recent studies focusing on spatial pattern of different soil enzymes in the terrestrial environment. Whereas zymography allows the visualization of enzyme pattern in the close vicinity of roots, micro-sampling strategies followed by MUF analyses clarify micro-scale pattern of enzymes associated to specific microhabitats (micro-aggregates, organo-mineral complexes, subsoil compartments).

  17. Geological substrates shape tree species and trait distributions in African moist forests.

    Science.gov (United States)

    Fayolle, Adeline; Engelbrecht, Bettina; Freycon, Vincent; Mortier, Frédéric; Swaine, Michael; Réjou-Méchain, Maxime; Doucet, Jean-Louis; Fauvet, Nicolas; Cornu, Guillaume; Gourlet-Fleury, Sylvie

    2012-01-01

    Understanding the factors that shape the distribution of tropical tree species at large scales is a central issue in ecology, conservation and forest management. The aims of this study were to (i) assess the importance of environmental factors relative to historical factors for tree species distributions in the semi-evergreen forests of the northern Congo basin; and to (ii) identify potential mechanisms explaining distribution patterns through a trait-based approach. We analyzed the distribution patterns of 31 common tree species in an area of more than 700,000 km(2) spanning the borders of Cameroon, the Central African Republic, and the Republic of Congo using forest inventory data from 56,445 0.5-ha plots. Spatial variation of environmental (climate, topography and geology) and historical factors (human disturbance) were quantified from maps and satellite records. Four key functional traits (leaf phenology, shade tolerance, wood density, and maximum growth rate) were extracted from the literature. The geological substrate was of major importance for the distribution of the focal species, while climate and past human disturbances had a significant but lesser impact. Species distribution patterns were significantly related to functional traits. Species associated with sandy soils typical of sandstone and alluvium were characterized by slow growth rates, shade tolerance, evergreen leaves, and high wood density, traits allowing persistence on resource-poor soils. In contrast, fast-growing pioneer species rarely occurred on sandy soils, except for Lophira alata. The results indicate strong environmental filtering due to differential soil resource availability across geological substrates. Additionally, long-term human disturbances in resource-rich areas may have accentuated the observed patterns of species and trait distributions. Trait differences across geological substrates imply pronounced differences in population and ecosystem processes, and call for different

  18. Geological substrates shape tree species and trait distributions in African moist forests.

    Directory of Open Access Journals (Sweden)

    Adeline Fayolle

    Full Text Available Understanding the factors that shape the distribution of tropical tree species at large scales is a central issue in ecology, conservation and forest management. The aims of this study were to (i assess the importance of environmental factors relative to historical factors for tree species distributions in the semi-evergreen forests of the northern Congo basin; and to (ii identify potential mechanisms explaining distribution patterns through a trait-based approach.We analyzed the distribution patterns of 31 common tree species in an area of more than 700,000 km(2 spanning the borders of Cameroon, the Central African Republic, and the Republic of Congo using forest inventory data from 56,445 0.5-ha plots. Spatial variation of environmental (climate, topography and geology and historical factors (human disturbance were quantified from maps and satellite records. Four key functional traits (leaf phenology, shade tolerance, wood density, and maximum growth rate were extracted from the literature. The geological substrate was of major importance for the distribution of the focal species, while climate and past human disturbances had a significant but lesser impact. Species distribution patterns were significantly related to functional traits. Species associated with sandy soils typical of sandstone and alluvium were characterized by slow growth rates, shade tolerance, evergreen leaves, and high wood density, traits allowing persistence on resource-poor soils. In contrast, fast-growing pioneer species rarely occurred on sandy soils, except for Lophira alata.The results indicate strong environmental filtering due to differential soil resource availability across geological substrates. Additionally, long-term human disturbances in resource-rich areas may have accentuated the observed patterns of species and trait distributions. Trait differences across geological substrates imply pronounced differences in population and ecosystem processes, and call for

  19. Geological Substrates Shape Tree Species and Trait Distributions in African Moist Forests

    Science.gov (United States)

    Fayolle, Adeline; Engelbrecht, Bettina; Freycon, Vincent; Mortier, Frédéric; Swaine, Michael; Réjou-Méchain, Maxime; Doucet, Jean-Louis; Fauvet, Nicolas; Cornu, Guillaume; Gourlet-Fleury, Sylvie

    2012-01-01

    Background Understanding the factors that shape the distribution of tropical tree species at large scales is a central issue in ecology, conservation and forest management. The aims of this study were to (i) assess the importance of environmental factors relative to historical factors for tree species distributions in the semi-evergreen forests of the northern Congo basin; and to (ii) identify potential mechanisms explaining distribution patterns through a trait-based approach. Methodology/Principal Findings We analyzed the distribution patterns of 31 common tree species in an area of more than 700,000 km2 spanning the borders of Cameroon, the Central African Republic, and the Republic of Congo using forest inventory data from 56,445 0.5-ha plots. Spatial variation of environmental (climate, topography and geology) and historical factors (human disturbance) were quantified from maps and satellite records. Four key functional traits (leaf phenology, shade tolerance, wood density, and maximum growth rate) were extracted from the literature. The geological substrate was of major importance for the distribution of the focal species, while climate and past human disturbances had a significant but lesser impact. Species distribution patterns were significantly related to functional traits. Species associated with sandy soils typical of sandstone and alluvium were characterized by slow growth rates, shade tolerance, evergreen leaves, and high wood density, traits allowing persistence on resource-poor soils. In contrast, fast-growing pioneer species rarely occurred on sandy soils, except for Lophira alata. Conclusions/Significance The results indicate strong environmental filtering due to differential soil resource availability across geological substrates. Additionally, long-term human disturbances in resource-rich areas may have accentuated the observed patterns of species and trait distributions. Trait differences across geological substrates imply pronounced

  20. Ecosystem scenarios shape fishermen spatial behavior. The case of the Peruvian anchovy fishery in the Northern Humboldt Current System

    Science.gov (United States)

    Joo, Rocio; Bertrand, Arnaud; Bouchon, Marilu; Chaigneau, Alexis; Demarcq, Hervé; Tam, Jorge; Simier, Monique; Gutiérrez, Dimitri; Gutiérrez, Mariano; Segura, Marceliano; Fablet, Ronan; Bertrand, Sophie

    2014-11-01

    A major goal in marine ecology is the understanding of the interactions between the dynamics of the different ecosystem components, from physics to top predators. While fishermen are among the main top predators at sea, almost none of the existing studies on ecology from physics to top predators contemplate fishermen as part of the system. The present work focuses on the coastal processes in the Northern Humboldt Current System, which encompasses both an intense climatic variability and the largest monospecific fishery of the world. From concomitant satellite, acoustic survey and Vessel Monitoring System data (∼90,000 fishing trips) for a ten-year period (2000-2009), we quantify the associations between the dynamics of the spatial behavior of fishermen, environmental conditions and anchovy (Engraulis ringens) biomass and spatial distribution. Using multivariate statistical analyses we show that environmental and anchovy conditions do significantly shape fishermen spatial behavior and present evidences that environmental fluctuations smoothed out along trophic levels. We propose a retrospective analysis of the study period in the light of the ecosystem scenarios evidenced and we finally discuss the potential use of fishermen spatial behavior as ecosystem indicator.

  1. Spatial Distribution of Soil Fauna In Long Term No Tillage

    Science.gov (United States)

    Corbo, J. Z. F.; Vieira, S. R.; Siqueira, G. M.

    2012-04-01

    The soil is a complex system constituted by living beings, organic and mineral particles, whose components define their physical, chemical and biological properties. Soil fauna plays an important role in soil and may reflect and interfere in its functionality. These organisms' populations may be influenced by management practices, fertilization, liming and porosity, among others. Such changes may reduce the composition and distribution of soil fauna community. Thus, this study aimed to determine the spatial variability of soil fauna in consolidated no-tillage system. The experimental area is located at Instituto Agronômico in Campinas (São Paulo, Brazil). The sampling was conducted in a Rhodic Eutrudox, under no tillage system and 302 points distributed in a 3.2 hectare area in a regular grid of 10.00 m x 10.00 m were sampled. The soil fauna was sampled with "Pitfall Traps" method and traps remained in the area for seven days. Data were analyzed using descriptive statistics to determine the main statistical moments (mean variance, coefficient of variation, standard deviation, skewness and kurtosis). Geostatistical tools were used to determine the spatial variability of the attributes using the experimental semivariogram. For the biodiversity analysis, Shannon and Pielou indexes and richness were calculated for each sample. Geostatistics has proven to be a great tool for mapping the spatial variability of groups from the soil epigeal fauna. The family Formicidae proved to be the most abundant and dominant in the study area. The parameters of descriptive statistics showed that all attributes studied showed lognormal frequency distribution for groups from the epigeal soil fauna. The exponential model was the most suited for the obtained data, for both groups of epigeal soil fauna (Acari, Araneae, Coleoptera, Formicidae and Coleoptera larva), and the other biodiversity indexes. The sampling scheme (10.00 m x 10.00 m) was not sufficient to detect the spatial

  2. Spatial distribution of cancer in Kohgilooyeh and Boyerahmad province

    Directory of Open Access Journals (Sweden)

    M Fararouei

    2016-02-01

    Full Text Available Spatial distribution of cancer is one of the powerful tools in epidemiology of cancer. The present study is designed to understand the geographical distribution of most frequent types of cancer in K&B province. Methods: All registered cases of cancer are reviewed and duplicate cases were removed. The data was analyzed using Arcgis software. Results: Of all registered cases, 1273  remained for analysis of which 57% were residences of urban areas. Cities including  Sisakht, Yasuj and Dehdsasht were shown to have highest incidence rates among the Urban areas. Dena, Sepidar and Kohmare Khaleghi had the highest rates among the rural areas in the province. Skin cancer was the most common type of cancer which had the highest rates of incidence in Sisakht and Dehdasht and Dena and Sepidar among urban and rural areas respectively. Conclusion: The distribution of cancer was not even in the province. Attitude and consumption of wild and regional plants are introduced as the potential risk factors for such a spatial distribution of the common cancers I the province. The results of this study could be used for further analytical studies to understand the regional etiology of cancer in the province.

  3. Dimension Synthesis of a Spatial Parallel Kinematic Manipulator Based on S-shaped Test Specimen

    Directory of Open Access Journals (Sweden)

    Liu Yuzhe

    2017-01-01

    Full Text Available With the development of the aerospace industry, the hybrid machine tool for machining the complicated curved surface is becoming a research hotspot. The S-shaped test specimen proposed by Chengdu Aircraft Industrial Company is an effective test method to verify the ability of machining the complicated curved surface for a machine tool. Considering the spatial parallel kinematic manipulator in a hybrid machine tool provides the complicated orientation motion and its design of structure dimension affects the accuracy of the machine tool, this paper investigates the issue about dimension synthesis of the manipulator based on S-shaped test specimen. By establishing models of the S-shaped test specimen and parallel kinematic manipulator, the motion trajectory of the parallel kinematic manipulator for machining S-shaped test specimen is obtained. According to the motion trajectory and expected performance indices, the result of dimension synthesis for the manipulator is plotted and a set of suitable dimensions is achieved. With the analysis result in this paper, it is helpful to improving the accuracy of machining the S-shaped test specimen.

  4. Temporal acceleration of spatially distributed kinetic Monte Carlo simulations

    International Nuclear Information System (INIS)

    Chatterjee, Abhijit; Vlachos, Dionisios G.

    2006-01-01

    The computational intensity of kinetic Monte Carlo (KMC) simulation is a major impediment in simulating large length and time scales. In recent work, an approximate method for KMC simulation of spatially uniform systems, termed the binomial τ-leap method, was introduced [A. Chatterjee, D.G. Vlachos, M.A. Katsoulakis, Binomial distribution based τ-leap accelerated stochastic simulation, J. Chem. Phys. 122 (2005) 024112], where molecular bundles instead of individual processes are executed over coarse-grained time increments. This temporal coarse-graining can lead to significant computational savings but its generalization to spatially lattice KMC simulation has not been realized yet. Here we extend the binomial τ-leap method to lattice KMC simulations by combining it with spatially adaptive coarse-graining. Absolute stability and computational speed-up analyses for spatial systems along with simulations provide insights into the conditions where accuracy and substantial acceleration of the new spatio-temporal coarse-graining method are ensured. Model systems demonstrate that the r-time increment criterion of Chatterjee et al. obeys the absolute stability limit for values of r up to near 1

  5. Origin of Pareto-like spatial distributions in ecosystems.

    Science.gov (United States)

    Manor, Alon; Shnerb, Nadav M

    2008-12-31

    Recent studies of cluster distribution in various ecosystems revealed Pareto statistics for the size of spatial colonies. These results were supported by cellular automata simulations that yield robust criticality for endogenous pattern formation based on positive feedback. We show that this patch statistics is a manifestation of the law of proportionate effect. Mapping the stochastic model to a Markov birth-death process, the transition rates are shown to scale linearly with cluster size. This mapping provides a connection between patch statistics and the dynamics of the ecosystem; the "first passage time" for different colonies emerges as a powerful tool that discriminates between endogenous and exogenous clustering mechanisms. Imminent catastrophic shifts (such as desertification) manifest themselves in a drastic change of the stability properties of spatial colonies.

  6. Spatial distributions at equilibrium under heterogeneous transient subdiffusion.

    Science.gov (United States)

    Berry, Hugues; Soula, Hédi A

    2014-01-01

    Experimental measurements of the mobility of macromolecules, especially proteins, in cells and their membranes consistently report transient subdiffusion with possibly position-dependent-non-homogeneous-properties. However, the spatiotemporal dynamics of protein mobility when transient subdiffusion is restricted to a subregion of space is still unclear. Here, we investigated the spatial distribution at equilibrium of proteins undergoing transient subdiffusion due to continuous-time random walks (CTRW) in a restricted subregion of a two-dimensional space. Our Monte-Carlo simulations suggest that this process leads to a non-homogeneous spatial distribution of the proteins at equilibrium, where proteins increasingly accumulate in the CTRW subregion as its anomalous properties are increasingly marked. In the case of transient CTRW, we show that this accumulation is dictated by the asymptotic Brownian regime and not by the initial anomalous transient dynamics. Moreover, our results also show that this dominance of the asymptotic Brownian regime cannot be simply generalized to other scenarios of transient subdiffusion. In particular, non-homogeneous transient subdiffusion due to hindrance by randomly-located immobile obstacles does not lead to such a strong local accumulation. These results suggest that, even though they exhibit the same time-dependence of the mean-squared displacement, the different scenarios proposed to account for subdiffusion in the cell lead to different protein distribution in space, even at equilibrium and without coupling with reaction.

  7. Spatial distributions at equilibrium under heterogeneous transient subdiffusion

    Directory of Open Access Journals (Sweden)

    Hugues eBerry

    2014-11-01

    Full Text Available Experimental measurements of the mobility of macromolecules, especially proteins, in cells and their membranes consistently report transient subdiffusion with possibly position-dependent -- nonhomogeneous -- properties. However, the spatiotemporal dynamics of protein mobility when transient subdiffusion is restricted to a subregion of space is still unclear. Here, we investigated the spatial distribution at equilibrium of proteins undergoing transient subdiffusion due to continuous-time random walks (CTRW in a restricted subregion of a two-dimensional space. Our Monte-Carlo simulations suggest that this process leads to a nonhomogeneous spatial distribution of the proteins at equilibrium, where proteins increasingly accumulate in the CTRW subregion as its anomalous properties are increasingly marked. In the case of transient CTRW, we show that this accumulation is dictated by the asymptotic Brownian regime and not by the initial anomalous transient dynamics. Moreover, our results also show that this dominance of the asymptotic Brownian regime cannot be simply generalized to other scenarios of transient subdiffusion. In particular, nonhomogeneous transient subdiffusion due to hindrance by randomly-located immobile obstacles does not lead to such a strong local accumulation. These results suggest that, even though they exhibit the same time-dependence of the mean-squared displacement, the different scenarios proposed to account for subdiffusion in the cell lead to different protein distribution in space, even at equilibrium and without coupling with reaction.

  8. Encoding into working memory of spatial location, color, and shape: electrophysiological investigations.

    Science.gov (United States)

    Martín-Loeches, M; Rubia, F J

    1997-10-01

    Event-related potentials (ERP) were recorded while subjects memorized either the location, the color or the shape of stimuli which could be located in 1 of 4 positions relative to a central fixation point (top, bottom, left or right), be of 1 of 4 positions relative to a central fixation point (top, bottom, left or right), be of 1 of 4 colors (white, green, red or blue), and present 1 of 4 shapes (triangle, cross, circle or square). These ERP were compared to ERP recorded while subjects looked at the same stimuli but performed other control, nonmemory tasks. Only ERP corresponding to the memorization of spatial location showed a differential pattern which could be specifically attributed to memory encoding processes. This reveals an important difference in ERP modulation between a working memory subsystem for spatial location and other subsystem (or subsystems) for color or shape, which would provide evidence supporting the existence of different working memory subsystems for visual information in the brain.

  9. Spatial relationship between tumor perfusion and endogeneous glucose distribution

    International Nuclear Information System (INIS)

    Schroeder, T.; Larrier, N.; Viglianti, B.; Rabbani, Z.N.; Peltz, C.; Vujascovic, Z.; Dewhirst, M.W.

    2003-01-01

    Earlier studies detecting glucose in tissue and solid tumors by bioluminescence imaging suggested, that glucose distribution patterns may be spatially related to functional vascularity. The purpose of this study was to evaluate this relationship by comparing glucose distribution patterns as determined by bioluminescence imaging to perfusion patterns of endogeneous Hoechst 33342 in rats bearing mammary carcinomas. R 3230 mammary carcinoma cells have been implanted subcutaneously into 7 female Fischer 344 rats. Two months post implantation, after injection of Hoechst 33342 the tumors were removed and snap frozen to conserve metabolite levels. Concomitantly, blood was sampled from the animals for analysis of glucose concentrations using a micodialysis analyzer. Cryosections of the tumors have been prepared, and every slice has been analyzed for both, Hoechst binding by fluorescence microscopy, and for glucose distribution patterns using bioluminescence imaging. In many cases vascular structures could be retrieved by the spatial pattern of glucose distribution. In some cases however, higher glucose concentrations could be found independent from Hoechst signal. On the other hand, regions of high Hoechst signal are not necessarily correlated with high glucose concentrations. When comparing blood and tissue glucose levels, tissue glucose content as measured with bioluminescence imaging (1.9-3.5 mM) is considerably lower than blood glucose (5.6-8.0 mM), demonstrating the expected gradient from blood to tissue. This study demonstrates the feasibility of monitoring glucose gradients in relation to functional vasculature throughout the body, from blood down to tissue or tumor and further, throughout the microenvironment of the solid tumor. Glucose distribution patterns may be an important tool in perfusion studies, e. g. in detecting the direction of blood flow in ex-vivo samples or in estimating glucose consumption rates of tumor cells adjacent to or in between perfused

  10. Digital autoradiography technique for studying of spatial Impurity distributions Delara

    International Nuclear Information System (INIS)

    Khamrayeva, S.

    2001-01-01

    In this report, the possibilities of the digital image processing for autoradiographic investigations of impurity distributions in the different objects (crystals, biology, geology et al) are shown. Activation autoradiography based on the secondary beta-irradiation is the method spread widely for investigations of the spatial distribution of chemical elements in the different objects. The analysis of autoradiography features is connected with the elucidation of optical density distribution of photoemulsion by means of photometry. The photoemulsion is used as detector of secondary beta irradiation. For different technological and nature materials to have elemental shifts the fine structure of chemical element distribution is often interested. But photometry makes it difficult to study the inhomogeneous chemical elements with the little gradient of concentration (near 20%). Therefore, the suppression of the background and betterment of linear solvability are the main problems of autoradiographic analysis. Application of the fast-acting digital computers and the technical means of signals treatment are allowed to spread the possibilities and the resolution of activation autoradiography. Mechanism of creation of autoradiographic features is described. The treatment of autoradiograms was conducted with the help of the dialogue system having matrix in 512 x 512 elements. For the interpretation of the experimental data clustering analysis methodology was used. Classification of the zones on the minimum of the square mistake was conducted according to the data of histograms of the optical densities of the studying autoradiograms. It was proposed algorithm for digital treatment for reconstruction of autoradiographic features. At a minimal contrast the resolution of the method has been enhanced on the degree by adaptation of methods of digital image processing (DIP) to suppress background activity. Results of the digital autoradiographic investigations of spatial impurity

  11. Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas

    Science.gov (United States)

    Kim, Jaewook; Nam, Y. U.; Lampert, M.; Ghim, Y.-C.

    2016-10-01

    A statistical method for the estimation of the spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, the sizes of averaging time windows and the ratios of the distance between the two measurement points to the true correlation length, and the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.

  12. Gaussian theory for spatially distributed self-propelled particles

    Science.gov (United States)

    Seyed-Allaei, Hamid; Schimansky-Geier, Lutz; Ejtehadi, Mohammad Reza

    2016-12-01

    Obtaining a reduced description with particle and momentum flux densities outgoing from the microscopic equations of motion of the particles requires approximations. The usual method, we refer to as truncation method, is to zero Fourier modes of the orientation distribution starting from a given number. Here we propose another method to derive continuum equations for interacting self-propelled particles. The derivation is based on a Gaussian approximation (GA) of the distribution of the direction of particles. First, by means of simulation of the microscopic model, we justify that the distribution of individual directions fits well to a wrapped Gaussian distribution. Second, we numerically integrate the continuum equations derived in the GA in order to compare with results of simulations. We obtain that the global polarization in the GA exhibits a hysteresis in dependence on the noise intensity. It shows qualitatively the same behavior as we find in particles simulations. Moreover, both global polarizations agree perfectly for low noise intensities. The spatiotemporal structures of the GA are also in agreement with simulations. We conclude that the GA shows qualitative agreement for a wide range of noise intensities. In particular, for low noise intensities the agreement with simulations is better as other approximations, making the GA to an acceptable candidates of describing spatially distributed self-propelled particles.

  13. Flow distributions and spatial correlations in human brain capillary networks

    Science.gov (United States)

    Lorthois, Sylvie; Peyrounette, Myriam; Larue, Anne; Le Borgne, Tanguy

    2015-11-01

    The vascular system of the human brain cortex is composed of a space filling mesh-like capillary network connected upstream and downstream to branched quasi-fractal arterioles and venules. The distribution of blood flow rates in these networks may affect the efficiency of oxygen transfer processes. Here, we investigate the distribution and correlation properties of blood flow velocities from numerical simulations in large 3D human intra-cortical vascular network (10000 segments) obtained from an anatomical database. In each segment, flow is solved from a 1D non-linear model taking account of the complex rheological properties of blood flow in microcirculation to deduce blood pressure, blood flow and red blood cell volume fraction distributions throughout the network. The network structural complexity is found to impart broad and spatially correlated Lagrangian velocity distributions, leading to power law transit time distributions. The origins of this behavior (existence of velocity correlations in capillary networks, influence of the coupling with the feeding arterioles and draining veins, topological disorder, complex blood rheology) are studied by comparison with results obtained in various model capillary networks of controlled disorder. ERC BrainMicroFlow GA615102, ERC ReactiveFronts GA648377.

  14. Spatial patterns of seaweed distribution in Malaysia using GIS

    Science.gov (United States)

    Lian, Du Hai; Sim, Jillian Ooi Lean; Fauzi, Rosmadi; Moi, Phang Siew

    2008-10-01

    The objective of this article is to represent spatial patterns of seaweed distribution in Malaysia. Seaweeds have been collected since 1984 along coastlines of 4675 km of peninsular Malaysia, Sabah, and Sarawak. However, there is no seaweed database and they cannot be displayed in a geographic view. Therefore, a database with 805 georeferenced observations was setup and GIS is used to analyze seaweed diversity based on this database. The highest number of observations is 94 which occur along east coastline of peninsular Malaysia. The highest number of species richness is 82 which are also along east coastline of peninsular Malaysia. Rhodophyta has the highest species richness while Chlorophyta has the least species richness.

  15. Agent-based Algorithm for Spatial Distribution of Objects

    KAUST Repository

    Collier, Nathan

    2012-06-02

    In this paper we present an agent-based algorithm for the spatial distribution of objects. The algorithm is a generalization of the bubble mesh algorithm, initially created for the point insertion stage of the meshing process of the finite element method. The bubble mesh algorithm treats objects in space as bubbles, which repel and attract each other. The dynamics of each bubble are approximated by solving a series of ordinary differential equations. We present numerical results for a meshing application as well as a graph visualization application.

  16. Effects of cell spatial organization and size distribution on ultrasound backscattering.

    Science.gov (United States)

    Saha, Ratan K; Kolios, Michael C

    2011-10-01

    comparable (d ~ λ/2), then the histograms were better fitted by the Nakagami distribution. This study suggests that the shape of an envelope histogram depends upon the periodicity in the spatial organization of scatterers and bandwidth of the ultrasound pulse.

  17. Efficient and accurate laser shaping with liquid crystal spatial light modulators

    Energy Technology Data Exchange (ETDEWEB)

    Maxson, Jared M.; Bartnik, Adam C.; Bazarov, Ivan V. [Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853 (United States)

    2014-10-27

    A phase-only spatial light modulator (SLM) is capable of precise transverse laser shaping by either functioning as a variable phase grating or by serving as a variable mask via polarization rotation. As a phase grating, the highest accuracy algorithms, based on computer generated holograms (CGHs), have been shown to yield extended laser shapes with <10% rms error, but conversely little is known about the experimental efficiency of the method in general. In this work, we compare the experimental tradeoff between error and efficiency for both the best known CGH method and polarization rotation-based intensity masking when generating hard-edged flat top beams. We find that the masking method performs comparably with CGHs, both having rms error < 10% with efficiency > 15%. Informed by best practices for high efficiency from a SLM phase grating, we introduce an adaptive refractive algorithm which has high efficiency (92%) but also higher error (16%), for nearly cylindrically symmetric cases.

  18. Shape from specular reflection in calibrated environments and the integration of spatial normal fields

    KAUST Repository

    Balzer, Jonathan

    2011-09-01

    Reflections of a scene in a mirror surface contain information on its shape. This information is accessible by measurement through an optical metrology technique called deflectometry. The result is a field of normal vectors to the unknown surface having the remarkable property that it equally changes in all spatial directions, unlike normal maps occurring, e.g., in Shape from Shading. Its integration into a zero-order reconstruction of the surface thus deserves special attention. We develop a novel algorithm for this purpose which is relatively straightforward to implement yet outperforms existing ones in terms of efficiency and robustness. Experimental results on synthetic and real data complement the theoretical discussion. © 2011 IEEE.

  19. Effects of laser beam propagation and saturation on the spatial shape of sodium laser guide stars.

    Science.gov (United States)

    Marc, Fabien; Guillet de Chatellus, Hugues; Pique, Jean-Paul

    2009-03-30

    The possibility to produce diffraction-limited images by large telescopes through Adaptive Optics is closely linked to the precision of measurement of the position of the guide star on the wavefront sensor. In the case of laser guide stars, many parameters can lead to a strong distortion on the shape of the LGS spot. Here we study the influence of both the saturation of the sodium layer excited by different types of lasers, the spatial quality of the laser mode at the ground and the influence of the atmospheric turbulence on the upward propagation of the laser beam. Both shape and intensity of the LGS spot are found to depend strongly on these three effects with important consequences on the precision on the wavefront analysis.

  20. Spatial and mass distributions of molecular clouds and spiral structure

    International Nuclear Information System (INIS)

    Kwan, J.; Valdes, F.; National Optical Astronomy Observatories, Tucson, AZ)

    1987-01-01

    The growth of molecular clouds resulting from cloud-cloud collisions and coalescence in the Galactic ring between 4 and 8 kpc are modeled, taking into account the presence of a spiral potential and the mutual cloud-cloud gravitational attraction. The mean lifetime of molecular clouds is determined to be about 200 million years. The clouds are present in both spiral arm and interarm regions, but a spiral pattern in their spatial distribution is clearly discernible, with the more massive clouds showing a stronger correlation with the spiral arms. As viewed from within the Galactic disk, however, it is very difficult to ascertain that the molecular cloud distribution in longitude-velocity space has a spiral pattern. 19 references

  1. Distribution patterns of fishes in a canyon-shaped reservoir

    Czech Academy of Sciences Publication Activity Database

    Prchalová, Marie; Kubečka, Jan; Vašek, Mojmír; Peterka, Jiří; Seďa, Jaromír; Jůza, Tomáš; Říha, Milan; Jarolím, Oldřich; Tušer, Michal; Kratochvíl, Michal; Čech, Martin; Draštík, Vladislav; Frouzová, Jaroslava; Hohausová, Eva

    2008-01-01

    Roč. 73, č. 1 (2008), s. 54-78 ISSN 0022-1112 R&D Projects: GA AV ČR(CZ) 1QS600170504; GA AV ČR(CZ) IAA600170502; GA ČR(CZ) GA206/07/1392 Institutional research plan: CEZ:AV0Z60170517 Keywords : longitudinal distribution * vertical distribution * fish community structure Subject RIV: EH - Ecology, Behaviour Impact factor: 1.246, year: 2008

  2. Estimation of the shape parameter of a generalized Pareto distribution based on a transformation to Pareto distributed variables

    OpenAIRE

    van Zyl, J. Martin

    2012-01-01

    Random variables of the generalized Pareto distribution, can be transformed to that of the Pareto distribution. Explicit expressions exist for the maximum likelihood estimators of the parameters of the Pareto distribution. The performance of the estimation of the shape parameter of generalized Pareto distributed using transformed observations, based on the probability weighted method is tested. It was found to improve the performance of the probability weighted estimator and performs good wit...

  3. A modal approach to modeling spatially distributed vibration energy dissipation.

    Energy Technology Data Exchange (ETDEWEB)

    Segalman, Daniel Joseph

    2010-08-01

    The nonlinear behavior of mechanical joints is a confounding element in modeling the dynamic response of structures. Though there has been some progress in recent years in modeling individual joints, modeling the full structure with myriad frictional interfaces has remained an obstinate challenge. A strategy is suggested for structural dynamics modeling that can account for the combined effect of interface friction distributed spatially about the structure. This approach accommodates the following observations: (1) At small to modest amplitudes, the nonlinearity of jointed structures is manifest primarily in the energy dissipation - visible as vibration damping; (2) Correspondingly, measured vibration modes do not change significantly with amplitude; and (3) Significant coupling among the modes does not appear to result at modest amplitudes. The mathematical approach presented here postulates the preservation of linear modes and invests all the nonlinearity in the evolution of the modal coordinates. The constitutive form selected is one that works well in modeling spatially discrete joints. When compared against a mathematical truth model, the distributed dissipation approximation performs well.

  4. Origin and spatial distribution of metals in agricultural soils

    International Nuclear Information System (INIS)

    Mohammadpour, Gh.A.; Karbassi, A.R.; Baghvand, A.

    2016-01-01

    Presence of toxic metals in agricultural soils can impose adverse health impact on consumers. The main purpose of this study was to determine spatial distribution of elements Fe, Sb, Mn in agriculture soils and crops of Hamedan Province in Iran. Soil samples (0-20 cm depth) were collected from an area of 2831 km 2 . Iron, Antimony and Manganese in samples of soil and agricultural crops were extracted and their amount was determined using atomic absorption spectrometer. The spatial distribution map of the studied elements was developed using Kriging method. The main concentration of Fe, Sb and Mn in the soil of the study area is about 3.8%, 2.5 and 403 mg/kg, respectively. According to chemical partitioning studies, the anthropogenic share of Fe, Sb and Mn is about 28.51%, 34.83% and 30.35%, respectively. Results of comparison of heavy metals pollution intensity in the agricultural soil with geoaccumulation index and also pollution index, illustrated that iron and manganese are classified in the Non-polluted class and antimony is in the moderately polluted class. Analysis of zoning map of pollution index showed that Fe, Sb and Mn are of geological sources. In fact, these metals are naturally found in soil. However, anthropogenic activities have led to more accumulation of these metals in the soil. The obtained health risk for metals in agricultural crops is indicative of safe value for consumers.

  5. Occurrence and spatial distribution of microplastics in sediments from Norderney

    International Nuclear Information System (INIS)

    Dekiff, Jens H.; Remy, Dominique; Klasmeier, Jörg; Fries, Elke

    2014-01-01

    The spatial distribution of small potential microplastics (SPM) ( 1 mm) was also examined. Small microparticles were extracted from 36 one kg sediment samples and analysed by visual microscopic inspection and partly by thermal desorption pyrolysis gas chromatography/mass spectrometry. The smallest particle size that could be analysed with this method was estimated to be 100 μm. The mean number of SPM at the three sampling sites (n = 12) was 1.7, 1.3 and 2.3 particles per kg dry sediment, respectively. SPM were identified as polypropylene, polyethylene, polyethylene terephthalate, polyvinylchloride, polystyrene and polyamide. The organic plastic additives found were benzophenone, 1,2-benzenedicarboxylic acid, dimethyl phthalate, diethylhexyl phthalate, dibutyl phthalate, diethyl phthalate, phenol and 2,4-di-tert-butylphenol. Particles were distributed rather homogenously and the occurrence of SPM did not correlate with that of VPD. -- Highlights: • The small-scale variability of small potential microplastics (<1 mm) occurrence in beach sediments was studied. • Within 500 m, small potential microplastics (<1 mm) were distributed rather homogeneously in investigated beach sediments. • The occurrence of small potential microplastics (<1 mm) did not correlate with that of visible plastic debris. • Procedural contamination of sediments by fibres (blank) constitutes an analytical problem. • These findings must be considered when setting up standardized monitoring protocols. -- On a small scale within 500 m, small microplastics are distributed rather homogeneously in sediments from the North Sea island of Norderney

  6. The Spatial Scope of Competition and the Geographical Distribution of Entrepreneurship: Magazine Foundings and the U.S. Post Office

    Directory of Open Access Journals (Sweden)

    Heather A. Haveman

    2014-04-01

    Full Text Available We propose that the geographic distribution of entrepreneurship evolves as developing communication systems alter the spatial scope of competition Our arguments imply that as spatial barriers to communication diminish founding events will be less sensitive to local context and more sensitive to distant competition. We test this argument with data on the first modern communication system, the US post office, and foundings of organizations that depended on it for distribution: magazine-publishing ventures. We find that as the postal system expanded, the spatial scope of competition among magazines increased: magazines in distant locations exerted more negative effects on local founding rates, whereas magazines in the focal location exerted less positive effects on local founding rates These findings reveal how spatial barriers to competition shape the geography of entrepreneurial activity.

  7. Spatial patterns of distribution and abundance of Harrisia portoricensis, an endangered Caribbean cactus

    Science.gov (United States)

    J. Rojas-Sandoval; E. J. Melendez-Ackerman; NO-VALUE

    2013-01-01

    Aims The spatial distribution of biotic and abiotic factors may play a dominant role in determining the distribution and abundance of plants in arid and semiarid environments. In this study, we evaluated how spatial patterns of microhabitat variables and the degree of spatial dependence of these variables influence the distribution and abundance of the endangered...

  8. Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

    NARCIS (Netherlands)

    Rietkerk, M.G.; Ouedraogo, T.; Kumar, L.; Sanou, S.; Langevelde, F. van; Kiema, A.; Koppel, J. van de; Andel, J. van; Hearne, J.; Skidmore, A.K.; Ridder, N. de; Stroosnijder, L.; Prins, H.H.T.

    2002-01-01

    We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

  9. Spatial arrangement and size distribution of normal faults, Buckskin detachment upper plate, Western Arizona

    Science.gov (United States)

    Laubach, S. E.; Hundley, T. H.; Hooker, J. N.; Marrett, R. A.

    2018-03-01

    Fault arrays typically include a wide range of fault sizes and those faults may be randomly located, clustered together, or regularly or periodically located in a rock volume. Here, we investigate size distribution and spatial arrangement of normal faults using rigorous size-scaling methods and normalized correlation count (NCC). Outcrop data from Miocene sedimentary rocks in the immediate upper plate of the regional Buckskin detachment-low angle normal-fault, have differing patterns of spatial arrangement as a function of displacement (offset). Using lower size-thresholds of 1, 0.1, 0.01, and 0.001 m, displacements range over 5 orders of magnitude and have power-law frequency distributions spanning ∼ four orders of magnitude from less than 0.001 m to more than 100 m, with exponents of -0.6 and -0.9. The largest faults with >1 m displacement have a shallower size-distribution slope and regular spacing of about 20 m. In contrast, smaller faults have steep size-distribution slopes and irregular spacing, with NCC plateau patterns indicating imposed clustering. Cluster widths are 15 m for the 0.1-m threshold, 14 m for 0.01-m, and 1 m for 0.001-m displacement threshold faults. Results demonstrate normalized correlation count effectively characterizes the spatial arrangement patterns of these faults. Our example from a high-strain fault pattern above a detachment is compatible with size and spatial organization that was influenced primarily by boundary conditions such as fault shape, mechanical unit thickness and internal stratigraphy on a range of scales rather than purely by interaction among faults during their propagation.

  10. Spatial and temporal distribution of onroad CO2 emissions at the Urban spatial scale

    Science.gov (United States)

    Song, Y.; Gurney, K. R.; Zhou, Y.; Mendoza, D. L.

    2011-12-01

    The Hestia Project is a multi-disciplinary effort to help better understand the spatial and temporal distribution of fossil fuel carbon dioxide (CO2) emission at urban scale. Onroad transportation is an essential source of CO2 emissions. This study examines two urban domains: Marion County (Indianapolis) and Los Angeles County and explores the methods and results associated with the spatial and temporal distribution of local urban onroad CO2 emissions. We utilize a bottom-up approach and spatially distribute county emissions based on the Annual Average Daily Traffic (AADT) counts provided by local Department of Transportation. The total amount of CO2 emissions is calculated by the National Mobile Inventory Model (NMIM) for Marion County and the EMission FACtors (EMFAC) model for Los Angeles County. The NMIM model provides CO2 emissions based on vehicle miles traveled (VMT) data at the county-level from the national county database (NCD). The EMFAC model provides CO2 emissions for California State based on vehicle activities, including VMT, vehicle population and fuel types. A GIS road atlas is retrieved from the US Census Bureau. Further spatial analysis and integration are performed by GIS software to distribute onroad CO2 emission according to the traffic volume. The temporal allocation of onroad CO2 emission is based on the hourly traffic data obtained from the Metropolitan Planning Orgnizations (MPO) for Marion County and Department of Transportation for Los Angeles County. The annual CO2 emissions are distributed according to each hourly fraction of traffic counts. Due to the fact that ATR stations are unevenly distributed in space, we create Thiessen polygons such that each road segment is linked to the nearest neighboring ATR station. The hourly profile for each individual station is then combined to create a "climatology" of CO2 emissions in time on each road segment. We find that for Marion County in the year 2002, urban interstate and arterial roads have

  11. Shape Design of Unsteady Forced Heat-convection Fields to Control Temperature Distribution History

    Science.gov (United States)

    Katamine, Eiji; Okada, Naoya

    2017-11-01

    This paper presents a numerical solution to shape design of unsteady forced heat-convection fields to control temperature to a prescribed distribution. The square error integral between the actual temperature distributions and the prescribed temperature distributions on the prescribed sub-domains during the specified period of time is used as the objective functional. Shape gradient of the shape design problem is derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. Numerical analyses program for the shape design is developed based on FreeFem++, and the validity of proposed method is confirmed by results of 2D numerical analyses.

  12. Environmental DNA reflects spatial and temporal jellyfish distribution.

    Science.gov (United States)

    Minamoto, Toshifumi; Fukuda, Miho; Katsuhara, Koki R; Fujiwara, Ayaka; Hidaka, Shunsuke; Yamamoto, Satoshi; Takahashi, Kohji; Masuda, Reiji

    2017-01-01

    Recent development of environmental DNA (eDNA) analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica) as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean.

  13. Environmental DNA reflects spatial and temporal jellyfish distribution.

    Directory of Open Access Journals (Sweden)

    Toshifumi Minamoto

    Full Text Available Recent development of environmental DNA (eDNA analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean.

  14. Distributed force simulation for arbitrarily shaped IPMC actuators

    International Nuclear Information System (INIS)

    Martinez, M; Lumia, R

    2013-01-01

    This paper presents a simulation model that predicts the force output of arbitrarily shaped ionic polymer–metal composite (IPMC) actuators. Theoretical and experimental force measurements are compared for a triangular IPMC actuator with a tip length of 11 mm. The results show that the simulated tip force is within 80% of the experimentally determined value. Simulated electrical results for an artificial shark pectoral fin and a 7 mm × 17 mm actuator are also presented. In each case, the voltage is shown to decrease exponentially from the input point. The results of an ion migration simulation for a 180 μm cubic element of Nafion are presented for both a constant 2 V input and a 2 V 0.25 Hz sine signal. Finally, the simulated deformation of an IPMC shark fin is shown. (paper)

  15. Patterns in the spatial distribution of Peruvian anchovy ( Engraulis ringens) revealed by spatially explicit fishing data

    Science.gov (United States)

    Bertrand, Sophie; Díaz, Erich; Lengaigne, Matthieu

    2008-10-01

    Peruvian anchovy ( Engraulis ringens) stock abundance is tightly driven by the high and unpredictable variability of the Humboldt Current Ecosystem. Management of the fishery therefore cannot rely on mid- or long-term management policy alone but needs to be adaptive at relatively short time scales. Regular acoustic surveys are performed on the stock at intervals of 2 to 4 times a year, but there is a need for more time continuous monitoring indicators to ensure that management can respond at suitable time scales. Existing literature suggests that spatially explicit data on the location of fishing activities could be used as a proxy for target stock distribution. Spatially explicit commercial fishing data could therefore guide adaptive management decisions at shorter time scales than is possible through scientific stock surveys. In this study we therefore aim to (1) estimate the position of fishing operations for the entire fleet of Peruvian anchovy purse-seiners using the Peruvian satellite vessel monitoring system (VMS), and (2) quantify the extent to which the distribution of purse-seine sets describes anchovy distribution. To estimate fishing set positions from vessel tracks derived from VMS data we developed a methodology based on artificial neural networks (ANN) trained on a sample of fishing trips with known fishing set positions (exact fishing positions are known for approximately 1.5% of the fleet from an at-sea observer program). The ANN correctly identified 83% of the real fishing sets and largely outperformed comparative linear models. This network is then used to forecast fishing operations for those trips where no observers were onboard. To quantify the extent to which fishing set distribution was correlated to stock distribution we compared three metrics describing features of the distributions (the mean distance to the coast, the total area of distribution, and a clustering index) for concomitant acoustic survey observations and fishing set positions

  16. From spatial ecology to spatial epidemiology: modeling spatial distributions of different cancer types with principal coordinates of neighbor matrices.

    Science.gov (United States)

    Voutilainen, Ari; Tolppanen, Anna-Maija; Vehviläinen-Julkunen, Katri; Sherwood, Paula R

    2014-01-01

    Epidemiology and ecology share many fundamental research questions. Here we describe how principal coordinates of neighbor matrices (PCNM), a method from spatial ecology, can be applied to spatial epidemiology. PCNM is based on geographical distances among sites and can be applied to any set of sites providing a good coverage of a study area. In the present study, PCNM eigenvectors corresponding to positive autocorrelation were used as explanatory variables in linear regressions to model incidences of eight most common cancer types in Finnish municipalities (n = 320). The dataset was provided by the Finnish Cancer Registry and it included altogether 615,839 cases between 1953 and 2010. PCNM resulted in 165 vectors with a positive eigenvalue. The first PCNM vector corresponded to the wavelength of hundreds of kilometers as it contrasted two main subareas so that municipalities located in southwestern Finland had the highest positive site scores and those located in midwestern Finland had the highest negative scores in that vector. Correspondingly, the 165(th) PCNM vector indicated variation mainly between the two small municipalities located in South Finland. The vectors explained 13 - 58% of the spatial variation in cancer incidences. The number of outliers having standardized residual > |3| was very low, one to six per model, and even lower, zero to two per model, according to Chauvenet's criterion. The spatial variation of prostate cancer was best captured (adjusted r (2) = 0.579). PCNM can act as a complementary method to causal modeling to achieve a better understanding of the spatial structure of both the response and explanatory variables, and to assess the spatial importance of unmeasured explanatory factors. PCNM vectors can be used as proxies for demographics and causative agents to deal with autocorrelation, multicollinearity, and confounding variables. PCNM may help to extend spatial epidemiology to areas with limited availability of

  17. Spatial bedrock erosion distribution in a natural gorge

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

    2015-12-01

    Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half

  18. Spatial distribution of venous gas emboli in the lungs

    Science.gov (United States)

    Souders, J. E.; Doshier, J. B.; Polissar, N. L.; Hlastala, M. P.

    1999-01-01

    The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-microm fluorescent microspheres at baseline and during N(2) embolism. The animals were killed, and the lungs were excised, air-dried, and diced into approximately 2-cm(3) pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 +/- 1% per additional centimeter in height compared with baseline (P = 0.0003). Embolism also increased radially by 3 +/- 1%/cm from the hilum (P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 +/- 2% for every 1. 0 increase in relative baseline flow (P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature.

  19. Integrating water by plant roots over spatially distributed soil salinity

    Science.gov (United States)

    Homaee, Mehdi; Schmidhalter, Urs

    2010-05-01

    In numerical simulation models dealing with water movement and solute transport in vadose zone, the water budget largely depends on uptake patterns by plant roots. In real field conditions, the uptake pattern largely changes in time and space. When dealing with soil and water salinity, most saline soils demonstrate spatially distributed osmotic head over the root zone. In order to quantify such processes, the major difficulty stems from lacking a sink term function that adequately accounts for the extraction term especially under variable soil water osmotic heads. The question of how plants integrate such space variable over its rooting depth remains as interesting issue for investigators. To move one step forward towards countering this concern, a well equipped experiment was conducted under heterogeneously distributed salinity over the root zone with alfalfa. The extraction rates of soil increments were calculated with the one dimensional form of Richards equation. The results indicated that the plant uptake rate under different mean soil salinities preliminary reacts to soil salinity, whereas at given water content and salinity the "evaporative demand" and "root activity" become more important to control the uptake patterns. Further analysis revealed that root activity is inconstant when imposed to variable soil salinity. It can be concluded that under heterogeneously distributed salinity, most water is taken from the less saline increment while the extraction from other root zone increments with higher salinities never stops.

  20. Spatial distribution of Guaiacum sanctum (Zygophyllaceae seedlings and saplings relative to canopy cover in Palo Verde National Park, Costa Rica

    Directory of Open Access Journals (Sweden)

    Eric J. Fuchs

    2013-09-01

    Full Text Available The spatial distribution of individuals is a fundamental property of most species and constitutes essential information for the development of restoration and conservation strategies, especially for endangered plant species. In this paper we describe the spatial distribution of different size classes of the endangered tropical tree Guaiacum sanctum and the effect of canopy cover on spatial aggregation. Adult G. sanctum were located and mapped in a 50ha plot in Palo Verde National Park, Costa Rica. Seedlings, saplings and juveniles were mapped to the nearest centimetre and permanently marked in three 50x50m subplots. Within each subplot spatial aggregation was assessed using Ripley’s K statistic and canopy opening readings were performed every 5m using a densitometer. Kriging spatial interpolation and Monte Carlo simulations were used to determine if average canopy cover differed among size classes. Individuals of G. sanctum were spatially aggregated at all size classes with seedlings being the most frequent size class in all subplots. Seedlings were found predominantly in areas with significantly higher canopy cover. In contrast, juveniles were more likely found in areas with higher light availability. The high number of seedlings, saplings, and juveniles relative to adults suggests that populations of G. sanctum in PVNP are expanding. Light availability and canopy structure are important factors shaping the spatial distribution of this species. The contemporary demographic structure of G. sanctum is dependent on forest gap dynamics and changes in human disturbance during the past 25 years.

  1. Macular pigment spatial distribution effects on glare disability.

    Science.gov (United States)

    Putnam, Christopher M; Bassi, Carl J

    2015-01-01

    This project explored the relationship of the macular pigment optical density (MPOD) spatial profile with measures of glare disability (GD) across the macula. A novel device was used to measure MPOD across the central 16° of retina along four radii using customized heterochromatic flicker photometry (cHFP)at eccentricities of 0°, 2°, 4°, 6° and 8°. MPOD was measured as discrete and integrated values at all measured retinal loci. GD was calculated as a difference in contrast sensitivity (CS) between no glare and glare conditions using identical stimuli presented at the same eccentricities. GD was defined as [(CSNo Glare-CSGlare)/CSNo Glare] in order to isolate the glare attenuation effects of MPOD by controlling for CS variability among the subject sample. Correlations of the discrete and integrated MPOD with GD were compared. The cHFP identified reliable MPOD spatial distribution maps demonstrating a 1st-order exponential decay as a function of increasing eccentricity. There was a significant negative correlation between both measures of foveal MPOD and GD using 6 cycles per degree (cpd) and 9 cpd stimuli. Significant correlations were found between corresponding parafoveal MPOD measures and GD at 2 and 4° of eccentricity using 9 cpd stimuli with greater MPOD associated with less glare disability. These results are consistent with the glare attenuation effects of MP at higher spatial frequencies and support the hypothesis that discrete and integrated measures of MPOD have similar correlations with glare attenuation effects across the macula. Additionally, peak foveal MPOD appears to influence GD across the macula. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  2. Determination and optimization of spatial samples for distributed measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Xiaoming (Georgia Institute of Technology, Atlanta, GA); Tran, Hy D.; Shilling, Katherine Meghan; Kim, Heeyong (Georgia Institute of Technology, Atlanta, GA)

    2010-10-01

    There are no accepted standards for determining how many measurements to take during part inspection or where to take them, or for assessing confidence in the evaluation of acceptance based on these measurements. The goal of this work was to develop a standard method for determining the number of measurements, together with the spatial distribution of measurements and the associated risks for false acceptance and false rejection. Two paths have been taken to create a standard method for selecting sampling points. A wavelet-based model has been developed to select measurement points and to determine confidence in the measurement after the points are taken. An adaptive sampling strategy has been studied to determine implementation feasibility on commercial measurement equipment. Results using both real and simulated data are presented for each of the paths.

  3. Survey gear calibration independent of spatial fish distribution

    DEFF Research Database (Denmark)

    Lewy, Peter; Nielsen, J. Rasmus; Hovgård, Holger

    2004-01-01

    Trawl surveys provide important information for evaluation of relative stock abundance fluctuations over time. Therefore, when survey gears or vessels are changed, it is important to compare the efficiency and selectivity of old and new gears and vessels. A method for estimation of conversion...... factors is developed based on a survey design where paired hauls are taken in the same trawl track line. The method explicitly accounts for changes in fish density caused by trawling disturbance. A generalized linear model for paired hauls catches is analytically derived and the gear conversion...... and disturbance parameters with their precision are obtained using standard software. Simulation studies carried out additionally showed that the estimated conversion factors were practically unbiased. Because of the independence of the spatial fish distribution, the new method is preferable to the traditional...

  4. Wind Farms’ Spatial Distribution Effect on Power System Reserves Requirements

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio

    2010-01-01

    The wind power development during last millennium was typically based on small wind turbines dispersed over large areas, leading to a significant smoothing of the wind power fluctuations in a power system balancing area. The present development goes towards much larger wind farms, concentrated...... in smaller areas, which causes the total wind power fluctuations in power system areas to increase significantly. The impact of future large wind farms spatial distribution with respect to the power system reserve requirements is analyzed in this paper. For this purpose, Correlated Wind (CorWind) power time...... series simulation model developed to simulate wind power variability over a large area is used. As a study case, two scenarios for short term offshore wind power development in the West Danish power system region are used. The first scenario assumes that all the wind farms are built in the region...

  5. Climate change and spatial distribution of vegetation in Colombia

    Directory of Open Access Journals (Sweden)

    Juan Carlos Alarcon Hincapie

    2013-12-01

    Full Text Available Vegetation change under two climate change scenarios in different periods of the 21st Century are modeled for Colombia. Vegetation for the years 1970 to 2000 was reproduced using the Holdridge model with climate data with a spatial resolution of 900 meters. The vegetation types that occupied the most territory were sub-humid tropical forest, tropical dry forest and Andean wet forest. These results were validated by comparing with the Colombian ecosystem map (SINA, 2007, which confirmed a high degree of similarity between the modeled spatial vegetation patterns and modern ecosystem distributions. Future vegetation maps were simulated using data generated by a regional climate model under two scenarios (A2 and B2; IPCC, 2007 for the periods 2011-2040 and 2070-2100. Based on our predictions high altitude vegetation will convert to that of lower altitudes and drier provinces with the most dramatic change occurring in the A2 scenario from 2070-2100. The most affected areas are the páramo and other high Andean vegetation types, which in the timeframe of the explored scenarios will disappear by the middle of the 21st Century.

  6. Time-resolved spatial distribution measurements of pulse-modulated argon plasmas in an inductively coupled plasma reactor

    Science.gov (United States)

    Park, Ji-Hwan; Kim, Dong-Hwan; Kim, Yu-Sin; Chung, Chin-Wook

    2017-05-01

    The time variation of the plasma parameters along with their spatial distributions were measured in pulse-modulated (PM) inductively coupled argon plasma via the phase delay harmonic analysis method (PDHAM). During the initial active-glow, the distributions of both the ion flux and the electron temperature in the plasma bulk have M-shaped profiles due to the antenna geometry. Then, while the plasma is approaching a steady state, the spatial distribution evolves into a profile with a convex shape. The effects of the antenna geometry and the time evolution on the distribution profile are lesser under low gas pressure, and diminish at the wafer level. The diffusion of the charged particles and the nonlocal electron kinetics account for these characteristics. It is observed that the initial distribution of the electron temperature is affected by the electron density distribution of the previous after-glow at the wafer level. The distribution profiles at different pulse frequencies were also measured. At higher pulse frequencies, the distribution profile is more frequently smoothed by diffusion during the after-glow, leading to higher uniformity.

  7. Spatial Distribution of Black Bear Incident Reports in Michigan.

    Directory of Open Access Journals (Sweden)

    Jamie E McFadden-Hiller

    Full Text Available Interactions between humans and carnivores have existed for centuries due to competition for food and space. American black bears are increasing in abundance and populations are expanding geographically in many portions of its range, including areas that are also increasing in human density, often resulting in associated increases in human-bear conflict (hereafter, bear incidents. We used public reports of bear incidents in Michigan, USA, from 2003-2011 to assess the relative contributions of ecological and anthropogenic variables in explaining the spatial distribution of bear incidents and estimated the potential risk of bear incidents. We used weighted Normalized Difference Vegetation Index mean as an index of primary productivity, region (i.e., Upper Peninsula or Lower Peninsula, primary and secondary road densities, and percentage land cover type within 6.5-km2 circular buffers around bear incidents and random points. We developed 22 a priori models and used generalized linear models and Akaike's Information Criterion (AIC to rank models. The global model was the best compromise between model complexity and model fit (w = 0.99, with a ΔAIC 8.99 units from the second best performing model. We found that as deciduous forest cover increased, the probability of bear incident occurrence increased. Among the measured anthropogenic variables, cultivated crops and primary roads were the most important in our AIC-best model and were both positively related to the probability of bear incident occurrence. The spatial distribution of relative bear incident risk varied markedly throughout Michigan. Forest cover fragmented with agriculture and other anthropogenic activities presents an environment that likely facilitates bear incidents. Our map can help wildlife managers identify areas of bear incident occurrence, which in turn can be used to help develop strategies aimed at reducing incidents. Researchers and wildlife managers can use similar mapping

  8. Spatial Distribution of Black Bear Incident Reports in Michigan.

    Science.gov (United States)

    McFadden-Hiller, Jamie E; Beyer, Dean E; Belant, Jerrold L

    2016-01-01

    Interactions between humans and carnivores have existed for centuries due to competition for food and space. American black bears are increasing in abundance and populations are expanding geographically in many portions of its range, including areas that are also increasing in human density, often resulting in associated increases in human-bear conflict (hereafter, bear incidents). We used public reports of bear incidents in Michigan, USA, from 2003-2011 to assess the relative contributions of ecological and anthropogenic variables in explaining the spatial distribution of bear incidents and estimated the potential risk of bear incidents. We used weighted Normalized Difference Vegetation Index mean as an index of primary productivity, region (i.e., Upper Peninsula or Lower Peninsula), primary and secondary road densities, and percentage land cover type within 6.5-km2 circular buffers around bear incidents and random points. We developed 22 a priori models and used generalized linear models and Akaike's Information Criterion (AIC) to rank models. The global model was the best compromise between model complexity and model fit (w = 0.99), with a ΔAIC 8.99 units from the second best performing model. We found that as deciduous forest cover increased, the probability of bear incident occurrence increased. Among the measured anthropogenic variables, cultivated crops and primary roads were the most important in our AIC-best model and were both positively related to the probability of bear incident occurrence. The spatial distribution of relative bear incident risk varied markedly throughout Michigan. Forest cover fragmented with agriculture and other anthropogenic activities presents an environment that likely facilitates bear incidents. Our map can help wildlife managers identify areas of bear incident occurrence, which in turn can be used to help develop strategies aimed at reducing incidents. Researchers and wildlife managers can use similar mapping techniques to

  9. On the distributions of annual and seasonal daily rainfall extremes in central Arizona and their spatial variability

    Science.gov (United States)

    Mascaro, Giuseppe

    2018-04-01

    This study uses daily rainfall records of a dense network of 240 gauges in central Arizona to gain insights on (i) the variability of the seasonal distributions of rainfall extremes; (ii) how the seasonal distributions affect the shape of the annual distribution; and (iii) the presence of spatial patterns and orographic control for these distributions. For this aim, recent methodological advancements in peak-over-threshold analysis and application of the Generalized Pareto Distribution (GPD) were used to assess the suitability of the GPD hypothesis and improve the estimation of its parameters, while limiting the effect of short sample sizes. The distribution of daily rainfall extremes was found to be heavy-tailed (i.e., GPD shape parameter ξ > 0) during the summer season, dominated by convective monsoonal thunderstorms. The exponential distribution (a special case of GPD with ξ = 0) was instead showed to be appropriate for modeling wintertime daily rainfall extremes, mainly caused by cold fronts transported by westerly flow. The annual distribution exhibited a mixed behavior, with lighter upper tails than those found in summer. A hybrid model mixing the two seasonal distributions was demonstrated capable of reproducing the annual distribution. Organized spatial patterns, mainly controlled by elevation, were observed for the GPD scale parameter, while ξ did not show any clear control of location or orography. The quantiles returned by the GPD were found to be very similar to those provided by the National Oceanic and Atmospheric Administration (NOAA) Atlas 14, which used the Generalized Extreme Value (GEV) distribution. Results of this work are useful to improve statistical modeling of daily rainfall extremes at high spatial resolution and provide diagnostic tools for assessing the ability of climate models to simulate extreme events.

  10. Spatial vision in insects is facilitated by shaping the dynamics of visual input through behavioural action

    Directory of Open Access Journals (Sweden)

    Martin eEgelhaaf

    2012-12-01

    Full Text Available Insects such as flies or bees, with their miniature brains, are able to control highly aerobatic flight manoeuvres and to solve spatial vision tasks, such as avoiding collisions with obstacles, landing on objects or even localizing a previously learnt inconspicuous goal on the basis of environmental cues. With regard to solving such spatial tasks, these insects still outperform man-made autonomous flying systems. To accomplish their extraordinary performance, flies and bees have been shown by their characteristic behavioural actions to actively shape the dynamics of the image flow on their eyes (optic flow. The neural processing of information about the spatial layout of the environment is greatly facilitated by segregating the rotational from the translational optic flow component through a saccadic flight and gaze strategy. This active vision strategy thus enables the nervous system to solve apparently complex spatial vision tasks in a particularly efficient and parsimonious way. The key idea of this review is that biological agents, such as flies or bees, acquire at least part of their strength as autonomous systems through active interactions with their environment and not by simply processing passively gained information about the world. These agent-environment interactions lead to adaptive behaviour in surroundings of a wide range of complexity. Animals with even tiny brains, such as insects, are capable of performing extraordinarily well in their behavioural contexts by making optimal use of the closed action–perception loop. Model simulations and robotic implementations show that the smart biological mechanisms of motion computation and visually-guided flight control might be helpful to find technical solutions, for example, when designing micro air vehicles carrying a miniaturized, low-weight on-board processor.

  11. Retinal Ganglion Cell Distribution and Spatial Resolving Power in Deep-Sea Lanternfishes (Myctophidae)

    KAUST Repository

    De Busserolles, Fanny

    2014-01-01

    Topographic analyses of retinal ganglion cell density are very useful in providing information about the visual ecology of a species by identifying areas of acute vision within the visual field (i.e. areas of high cell density). In this study, we investigated the neural cell distribution in the ganglion cell layer of a range of lanternfish species belonging to 10 genera. Analyses were performed on wholemounted retinas using stereology. Topographic maps were constructed of the distribution of all neurons and both ganglion and amacrine cell populations in 5 different species from Nissl-stained retinas using cytological criteria. Amacrine cell distribution was also examined immunohistochemically in 2 of the 5 species using anti-parvalbumin antibody. The distributions of both the total neuron and the amacrine cell populations were aligned in all of the species examined, showing a general increase in cell density toward the retinal periphery. However, when the ganglion cell population was topographically isolated from the amacrine cell population, which comprised up to 80% of the total neurons within the ganglion cell layer, a different distribution was revealed. Topographic maps of the true ganglion cell distribution in 18 species of lanternfishes revealed well-defined specializations in different regions of the retina. Different species possessed distinct areas of high ganglion cell density with respect to both peak density and the location and/or shape of the specialized acute zone (i.e. elongated areae ventro-temporales, areae temporales and large areae centrales). The spatial resolving power was calculated to be relatively low (varying from 1.6 to 4.4 cycles per degree), indicating that myctophids may constitute one of the less visually acute groups of deep-sea teleosts. The diversity in retinal specializations and spatial resolving power within the family is assessed in terms of possible ecological functions and evolutionary history.

  12. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    International Nuclear Information System (INIS)

    Jehouani, A.; Merzouki, A.; Boutadghart, F.; Ghassoun, J.

    2007-01-01

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511 * MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique.

  13. Spatial distribution of erosion and deposition on an agricultural watershed

    Science.gov (United States)

    Pineux, Nathalie; Gilles, Colinet; Degré, Aurore

    2013-04-01

    To better understand the agricultural landscapes evolution becomes an essential preoccupation and, for this, it is needed to take into account the sediments deposition, in a distributed way. As it is not possible in practice to study all terrestrial surfaces in detail by instrumenting sectors to obtain data, models of prediction are valuable tools to control the current problems, to predict the future tendencies and to provide a scientific base to the political decisions. In our case, a landscape evolution model is needed, which aims at representing both erosion and sedimentation and dynamically adjusts the landscape to erosion and deposition by modifying the initial digital elevation model. The Landsoil model (Landscape design for Soil conservation under soil use and climate change), among others, could fulfil this objective. It has the advantage to take the soil variability into account. This model, designed for the analysis of agricultural landscape, is suitable for simulations from parcel to catchment scale, is spatially distributed and event-based. Observed quantitative data are essential (notably to calibrate the model) but still limited. Particularly, we lack observations spatially distributed on the watershed. For this purpose, we choose a watershed in Belgium (Wallonia) which is a 124 ha agricultural zone in the loamy region. Its slopes range from 0% to 9%. To test the predictions of the model, comparisons will be done with: - sediment measurements which are done with water samplings in four points on the site to compare the net erosion results; - sediment selective measurements (depth variation observed along graduated bares placed on site) to compare the erosion and deposition results; - very accurate DSM's (6,76 cm pixel resolution X-Y) obtained by the drone (Gatewing X100) each winter. Besides planning what the landscape evolution should be, a revision of the soil map (drew in 1958) is organized to compare with the past situation and establish how the

  14. Probability distributions of placental morphological measurements and origins of variability of placental shapes.

    Science.gov (United States)

    Yampolsky, M; Salafia, C M; Shlakhter, O

    2013-06-01

    While the mean shape of human placenta is round with centrally inserted umbilical cord, significant deviations from this ideal are fairly common, and may be clinically meaningful. Traditionally, they are explained by trophotropism. We have proposed a hypothesis explaining typical variations in placental shape by randomly determined fluctuations in the growth process of the vascular tree. It has been recently reported that umbilical cord displacement in a birth cohort has a log-normal probability distribution, which indicates that the displacement between an initial point of origin and the centroid of the mature shape is a result of accumulation of random fluctuations of the dynamic growth of the placenta. To confirm this, we investigate statistical distributions of other features of placental morphology. In a cohort of 1023 births at term digital photographs of placentas were recorded at delivery. Excluding cases with velamentous cord insertion, or missing clinical data left 1001 (97.8%) for which placental surface morphology features were measured. Best-fit statistical distributions for them were obtained using EasyFit. The best-fit distributions of umbilical cord displacement, placental disk diameter, area, perimeter, and maximal radius calculated from the cord insertion point are of heavy-tailed type, similar in shape to log-normal distributions. This is consistent with a stochastic origin of deviations of placental shape from normal. Deviations of placental shape descriptors from average have heavy-tailed distributions similar in shape to log-normal. This evidence points away from trophotropism, and towards a spontaneous stochastic evolution of the variants of placental surface shape features. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Spatial distribution of soil organic carbon stocks in France

    Directory of Open Access Journals (Sweden)

    M. P. Martin

    2011-05-01

    Full Text Available Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, thereby possibly influencing the course of climate change. Changes in soil organic carbon (SOC stocks are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOC stocks is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing around 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory.

    We calibrated a boosted regression tree model on the observed stocks, modelling SOC stocks as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOC stocks for mainland France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on SOC for such soils.

    The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOC stocks and pedo-climatic variables (plus their interactions over the French territory. These relationships strongly depended on the land use, and more specifically, differed between forest soils and cultivated soil. The total estimate of SOC stocks in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOC stock distributions of France, and consequently that the

  16. ML-Estimation in the Location-Scale-Shape Model of the Generalized Logistic Distribution

    OpenAIRE

    Abberger, Klaus

    2002-01-01

    A three parameter (location, scale, shape) generalization of the logistic distribution is fitted to data. Local maximum likelihood estimators of the parameters are derived. Although the likelihood function is unbounded, the likelihood equations have a consistent root. ML-estimation combined with the ECM algorithm allows the distribution to be easily fitted to data.

  17. Seed size, shape and vertical distribution in the soil : indicators of seed longevity

    NARCIS (Netherlands)

    Bekker, RM; Bakker, JP; Grandin, U; Kalamees, R; Milberg, P; Poschlod, P; Thompson, K; Willems, JH

    1998-01-01

    1. We investigated the vertical distribution of seeds in the soil, using data from nine studies in five European countries. We discovered significant correlations between seed shape and distribution in the soil. 2. The classification of the longevity of seeds of plant species has been improved by

  18. Shaping and monitoring of the mini-beam structures for the spatially fractionated hadron radiation therapy

    Directory of Open Access Journals (Sweden)

    I. Momot

    2016-06-01

    Full Text Available Design of collimators and their effectiveness for the purposes of the fractionated mini-beam hadron radiation therapy were evaluated by Monte Carlo simulations. The calculations have been performed for proton, carbon and oxygen ion beams at the energies relevant for medical applications. Micropixel metal and hybrid detectors were tested for measuring charged particles intensity distribution in multi-beam structures shaped by slit or matrix collimators exploring low energy proton beam at the Tandem generator (INR NASU, Kyiv. The results obtained illustrate reliable performance of the designed collimators as well as hybrid and metal microdetectors for measuring and imaging in real time the proton intensity distribution over mini-beam structures.

  19. Estimation of the Shape Parameter of Ged Distribution for a Small Sample Size

    Directory of Open Access Journals (Sweden)

    Purczyński Jan

    2014-06-01

    Full Text Available In this paper a new method of estimating the shape parameter of generalized error distribution (GED, called ‘approximated moment method’, was proposed. The following estimators were considered: the one obtained through the maximum likelihood method (MLM, approximated fast estimator (AFE, and approximated moment method (AMM. The quality of estimator was evaluated on the basis of the value of the relative mean square error. Computer simulations were conducted using random number generators for the following shape parameters: s = 0.5, s = 1.0 (Laplace distribution s = 2.0 (Gaussian distribution and s = 3.0.

  20. Voxel-Based Neighborhood for Spatial Shape Pattern Classification of Lidar Point Clouds with Supervised Learning.

    Science.gov (United States)

    Plaza-Leiva, Victoria; Gomez-Ruiz, Jose Antonio; Mandow, Anthony; García-Cerezo, Alfonso

    2017-03-15

    Improving the effectiveness of spatial shape features classification from 3D lidar data is very relevant because it is largely used as a fundamental step towards higher level scene understanding challenges of autonomous vehicles and terrestrial robots. In this sense, computing neighborhood for points in dense scans becomes a costly process for both training and classification. This paper proposes a new general framework for implementing and comparing different supervised learning classifiers with a simple voxel-based neighborhood computation where points in each non-overlapping voxel in a regular grid are assigned to the same class by considering features within a support region defined by the voxel itself. The contribution provides offline training and online classification procedures as well as five alternative feature vector definitions based on principal component analysis for scatter, tubular and planar shapes. Moreover, the feasibility of this approach is evaluated by implementing a neural network (NN) method previously proposed by the authors as well as three other supervised learning classifiers found in scene processing methods: support vector machines (SVM), Gaussian processes (GP), and Gaussian mixture models (GMM). A comparative performance analysis is presented using real point clouds from both natural and urban environments and two different 3D rangefinders (a tilting Hokuyo UTM-30LX and a Riegl). Classification performance metrics and processing time measurements confirm the benefits of the NN classifier and the feasibility of voxel-based neighborhood.

  1. Voxel-Based Neighborhood for Spatial Shape Pattern Classification of Lidar Point Clouds with Supervised Learning

    Directory of Open Access Journals (Sweden)

    Victoria Plaza-Leiva

    2017-03-01

    Full Text Available Improving the effectiveness of spatial shape features classification from 3D lidar data is very relevant because it is largely used as a fundamental step towards higher level scene understanding challenges of autonomous vehicles and terrestrial robots. In this sense, computing neighborhood for points in dense scans becomes a costly process for both training and classification. This paper proposes a new general framework for implementing and comparing different supervised learning classifiers with a simple voxel-based neighborhood computation where points in each non-overlapping voxel in a regular grid are assigned to the same class by considering features within a support region defined by the voxel itself. The contribution provides offline training and online classification procedures as well as five alternative feature vector definitions based on principal component analysis for scatter, tubular and planar shapes. Moreover, the feasibility of this approach is evaluated by implementing a neural network (NN method previously proposed by the authors as well as three other supervised learning classifiers found in scene processing methods: support vector machines (SVM, Gaussian processes (GP, and Gaussian mixture models (GMM. A comparative performance analysis is presented using real point clouds from both natural and urban environments and two different 3D rangefinders (a tilting Hokuyo UTM-30LX and a Riegl. Classification performance metrics and processing time measurements confirm the benefits of the NN classifier and the feasibility of voxel-based neighborhood.

  2. Airborne measurements of spatial NO2 distributions during AROMAT

    Science.gov (United States)

    Meier, Andreas Carlos; Seyler, André; Schönhardt, Anja; Richter, Andreas; Ruhtz, Thomas; Lindemann, Carsten; Burrows, John P.

    2015-04-01

    Nitrogen oxides, NOx (NOx = NO + NO2) play a key role in tropospheric chemistry. In addition to their directly harmful effects on the respiratory system of living organisms, they influence the levels of tropospheric ozone and contribute to acid rain and eutrophication of ecosystems. As they are produced in combustion processes, they can serve as an indicator for anthropogenic air pollution. In September 2014 several European research groups conducted the ESA funded Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign to test and intercompare newly developed airborne observation sytsems dedicated to air quality satellite validation studies. The IUP Bremen contributed to this campaign with its Airborne imaging DOAS instrument for Measurements of Atmospheric Pollution (AirMAP) on board a Cessna 207 turbo, operated by the FU Berlin. AirMAP allows the retrieval of integrated NO2 column densities in a stripe below the aircraft at a fine spatial resolution of up to 30 x 80 m2, at a typical flight altitude. Measurements have been performed over the city of Bucharest, creating for the first time high spatial resolution maps of Bucharest's NO2 distribution in a time window of approx. 2 hours. The observations were synchronised with ground-based car MAX-DOAS measurements for comparison. In addition, measurements were taken over the city of Berlin, Germany and at the Rovinari power plant, Romania. In this work the results of the research flights will be presented and conclusions will be drawn on the quality of the measurements, their applicability for satellite data validation and possible improvements for future measurements.

  3. Controls on the spatial distribution of oceanic δ13CDIC

    Directory of Open Access Journals (Sweden)

    P. B. Holden

    2013-03-01

    Full Text Available We describe the design and evaluation of a large ensemble of coupled climate–carbon cycle simulations with the Earth system model of intermediate complexity GENIE. This ensemble has been designed for application to a range of carbon cycle questions, including the causes of late-Quaternary fluctuations in atmospheric CO2. Here we evaluate the ensemble by applying it to a transient experiment over the recent industrial era (1858 to 2008 AD. We employ singular vector decomposition and principal component emulation to investigate the spatial modes of ensemble variability of oceanic dissolved inorganic carbon (DIC δ13C, considering both the spun-up pre-industrial state and the transient change. These analyses allow us to separate the natural (pre-industrial and anthropogenic controls on the δ13CDIC distribution. We apply the same dimensionally-reduced emulation techniques to consider the drivers of the spatial uncertainty in anthropogenic DIC. We show that the sources of uncertainty related to the uptake of anthropogenic δ13CDIC and DIC are quite distinct. Uncertainty in anthropogenic δ13C uptake is controlled by air–sea gas exchange, which explains 63% of modelled variance. This mode of variability is largely absent from the ensemble variability in CO2 uptake, which is rather driven by uncertainties in thermocline ventilation rates. Although the need to account for air–sea gas exchange is well known, these results suggest that, to leading order, uncertainties in the ocean uptake of anthropogenic 13C and CO2 are governed by very different processes. This illustrates the difficulties in reconstructing one from the other, and furthermore highlights the need for careful targeting of both δ13CDIC and DIC observations to better constrain the ocean sink of anthropogenic CO2.

  4. Spatial Distribution of Star Formation in High Redshift Galaxies

    Science.gov (United States)

    Cunnyngham, Ian; Takamiya, M.; Willmer, C.; Chun, M.; Young, M.

    2011-01-01

    Integral field unit spectroscopy taken of galaxies with redshifts between 0.6 and 0.8 utilizing Gemini Observatory’s GMOS instrument were used to investigate the spatial distribution of star-forming regions by measuring the Hβ and [OII]λ3727 emission line fluxes. These galaxies were selected based on the strength of Hβ and [OII]λ3727 as measured from slit LRIS/Keck spectra. The process of calibrating and reducing data into cubes -- possessing two spatial dimensions, and one for wavelength -- was automated via a custom batch script using the Gemini IRAF routines. Among these galaxies only the bluest sources clearly show [OII] in the IFU regardless of total galaxy luminosity. The brightest galaxies lack [OII] emission and it is posited that two different modes of star formation exist among this seemingly homogeneous group of z=0.7 star-forming galaxies. In order to increase the galaxy sample to include redshifts from 0.3 to 0.9, public Gemini IFU data are being sought. Python scripts were written to mine the Gemini Science Archive for candidate observations, cross-reference the target of these observations with information from the NASA Extragalactic Database, and then present the resultant database in sortable, searchable, cross-linked web-interface using Django to facilitate navigation. By increasing the sample, we expect to characterize these two different modes of star formation which could be high-redshift counterparts of the U/LIRGs and dwarf starburst galaxies like NGC 1569/NGC 4449. The authors acknowledge funds provided by the National Science Foundation (AST 0909240).

  5. Capturing multiple values of ecosystem services shaped by environmental worldviews: a spatial analysis.

    Science.gov (United States)

    Van Riper, Carena J; Kyle, Gerard T

    2014-12-01

    Two related approaches to valuing nature have been advanced in past research including the study of ecosystem services and psychological investigations of the factors that shape behavior. Stronger integration of the insights that emerge from these two lines of enquiry can more effectively sustain ecosystems, economies, and human well-being. Drawing on survey data collected from outdoor recreationists on Santa Cruz Island within Channel Islands National Park, U.S., our study blends these two research approaches to examine a range of tangible and intangible values of ecosystem services provided to stakeholders with differing biocentric and anthropocentric worldviews. We used Public Participation Geographic Information System methods to collect survey data and a Social Values for Ecosystem Services mapping application to spatially analyze a range of values assigned to terrestrial and aquatic ecosystems in the park. Our results showed that preferences for the provision of biological diversity, recreation, and scientific-based values of ecosystem services varied across a spatial gradient. We also observed differences that emerged from a comparison between survey subgroups defined by their worldviews. The implications emanating from this investigation aim to support environmental management decision-making in the context of protected areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. A Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil

    Science.gov (United States)

    Lane, John E.; Metzger, Philip T.; Wilkinson, R. Allen

    2010-01-01

    As part of ongoing efforts to develop models of lunar soil mechanics, this report reviews two topics that are important to discrete element method (DEM) modeling the behavior of soils (such as lunar soils): (1) methods of modeling particle shapes and (2) analytical representations of particle size distribution. The choice of particle shape complexity is driven primarily by opposing tradeoffs with total number of particles, computer memory, and total simulation computer processing time. The choice is also dependent on available DEM software capabilities. For example, PFC2D/PFC3D and EDEM support clustering of spheres; MIMES incorporates superquadric particle shapes; and BLOKS3D provides polyhedra shapes. Most commercial and custom DEM software supports some type of complex particle shape beyond the standard sphere. Convex polyhedra, clusters of spheres and single parametric particle shapes such as the ellipsoid, polyellipsoid, and superquadric, are all motivated by the desire to introduce asymmetry into the particle shape, as well as edges and corners, in order to better simulate actual granular particle shapes and behavior. An empirical particle size distribution (PSD) formula is shown to fit desert sand data from Bagnold. Particle size data of JSC-1a obtained from a fine particle analyzer at the NASA Kennedy Space Center is also fitted to a similar empirical PSD function.

  7. Modelling and predicting the spatial distribution of tree root density in heterogeneous forest ecosystems.

    Science.gov (United States)

    Mao, Zhun; Saint-André, Laurent; Bourrier, Franck; Stokes, Alexia; Cordonnier, Thomas

    2015-08-01

    In mountain ecosystems, predicting root density in three dimensions (3-D) is highly challenging due to the spatial heterogeneity of forest communities. This study presents a simple and semi-mechanistic model, named ChaMRoots, that predicts root interception density (RID, number of roots m(-2)). ChaMRoots hypothesizes that RID at a given point is affected by the presence of roots from surrounding trees forming a polygon shape. The model comprises three sub-models for predicting: (1) the spatial heterogeneity - RID of the finest roots in the top soil layer as a function of tree basal area at breast height, and the distance between the tree and a given point; (2) the diameter spectrum - the distribution of RID as a function of root diameter up to 50 mm thick; and (3) the vertical profile - the distribution of RID as a function of soil depth. The RID data used for fitting in the model were measured in two uneven-aged mountain forest ecosystems in the French Alps. These sites differ in tree density and species composition. In general, the validation of each sub-model indicated that all sub-models of ChaMRoots had good fits. The model achieved a highly satisfactory compromise between the number of aerial input parameters and the fit to the observed data. The semi-mechanistic ChaMRoots model focuses on the spatial distribution of root density at the tree cluster scale, in contrast to the majority of published root models, which function at the level of the individual. Based on easy-to-measure characteristics, simple forest inventory protocols and three sub-models, it achieves a good compromise between the complexity of the case study area and that of the global model structure. ChaMRoots can be easily coupled with spatially explicit individual-based forest dynamics models and thus provides a highly transferable approach for modelling 3-D root spatial distribution in complex forest ecosystems. © The Author 2015. Published by Oxford University Press on behalf of the

  8. Spatially distributed effects of mental exhaustion on resting-state FMRI networks

    NARCIS (Netherlands)

    Esposito, Fabrizio; Otto, Tobias; Zijlstra, Fred R H; Goebel, R.

    2014-01-01

    Brain activity during rest is spatially coherent over functional connectivity networks called resting-state networks. In resting-state functional magnetic resonance imaging, independent component analysis yields spatially distributed network representations reflecting distinct mental processes, such

  9. Factors driving the spatial layout of distribution channels

    NARCIS (Netherlands)

    Onstein, A.T.C.; Ektesaby, M.; Rezaei, J.; Tavasszy, L.A.; van Damme, D.A.

    2017-01-01

    Research statement Our study analyses the factors that drive decision-making on distribution structures, including the layout of distribution channels and the locations of distribution centres. Distribution is a primary firm activity, which strongly influences logistics costs and logistics

  10. The effects of spatially heterogeneous prey distributions on detection patterns in foraging seabirds.

    Directory of Open Access Journals (Sweden)

    Octavio Miramontes

    Full Text Available Many attempts to relate animal foraging patterns to landscape heterogeneity are focused on the analysis of foragers movements. Resource detection patterns in space and time are not commonly studied, yet they are tightly coupled to landscape properties and add relevant information on foraging behavior. By exploring simple foraging models in unpredictable environments we show that the distribution of intervals between detected prey (detection statistics is mostly determined by the spatial structure of the prey field and essentially distinct from predator displacement statistics. Detections are expected to be Poissonian in uniform random environments for markedly different foraging movements (e.g. Lévy and ballistic. This prediction is supported by data on the time intervals between diving events on short-range foraging seabirds such as the thick-billed murre (Uria lomvia. However, Poissonian detection statistics is not observed in long-range seabirds such as the wandering albatross (Diomedea exulans due to the fractal nature of the prey field, covering a wide range of spatial scales. For this scenario, models of fractal prey fields induce non-Poissonian patterns of detection in good agreement with two albatross data sets. We find that the specific shape of the distribution of time intervals between prey detection is mainly driven by meso and submeso-scale landscape structures and depends little on the forager strategy or behavioral responses.

  11. THE SPATIAL DISTRIBUTION OF OH AND CN RADICALS IN THE COMA OF COMET ENCKE

    International Nuclear Information System (INIS)

    Ihalawela, Chandrasiri A.; Pierce, Donna M.; Dorman, Garrett R.; Cochran, Anita L.

    2011-01-01

    Multiple potential parent species have been proposed to explain CN abundances in comet comae, but the parent has not been definitively identified for all comets. This study examines the spatial distribution of CN radicals in the coma of comet Encke and determines the likelihood that CN is a photodissociative daughter of HCN in the coma. Comet Encke is the shortest orbital period (3.3 years) comet known and also has a low dust-to-gas ratio based on optical observations. Observations of CN were obtained from 2003 October 22 to 24, using the 2.7 m telescope at McDonald Observatory. To determine the parent of CN, the classical vectorial model was modified by using a cone shape in order to reproduce Encke's highly aspherical and asymmetric coma. To test the robustness of the modified model, the spatial distribution of OH was also modeled. This also allowed us to obtain CN/OH ratios in the coma. Overall, we find the CN/OH ratio to be 0.009 ± 0.004. The results are consistent with HCN being the photodissociative parent of CN, but we cannot completely rule out other possible parents such as CH 3 CN and HC 3 N. We also found that the fan-like feature spans ∼90°, consistent with the results of Woodney et al..

  12. Beam shaping to improve holography techniques based on spatial light modulators

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2013-03-01

    Modern holographic techniques based on Spatial Light Modulators get serious benefits from providing uniform intensity distribution of a laser beam: more predictable and reliable operation, higher efficiency of laser energy usage, more simple mathematical description of diffraction transformations, etc. Conversion of Gaussian intensity distribution of TEM00 lasers to flattop one is successfully realized with refractive field mapping beam shapers like piShaper, which operational principle presumes transformation with high flatness of output wavefront, conserving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with several laser sources with different wavelengths simultaneously. Applying of these beam shapers brings serious benefits to the Spatial Light Modulator based techniques like Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

  13. Working models for spatial distribution and level of Mars' seismicity

    Science.gov (United States)

    Knapmeyer, M.; Oberst, J.; Hauber, E.; Wählisch, M.; Deuchler, C.; Wagner, R.

    2006-11-01

    We present synthetic catalogs of Mars quakes, intended to be used for performance assessments of future seismic networks on the planet. We have compiled a new inventory of compressional and extensional tectonic faults for the planet Mars, comprising 8500 faults with a total length of 680,000 km. The faults were mapped on the basis of Mars Orbiting Laser Altimeter (MOLA) shaded relief. Hence we expect to have assembled a homogeneous data set, not biased by illumination and viewing conditions of image data. Updated models of Martian crater statistics and geological maps were used to assign new maximum ages to all faults. On the basis of the fault catalog, spatial distributions of seismicity were simulated, using assumptions on the available annual seismic moment budget, the moment-frequency relationship, and a relation between rupture length and released moment. We have constructed five different models of Martian seismicity, predicting an annual moment release between 3.42 × 1016 Nm and 4.78 × 1018 Nm and up to 572 events with magnitudes greater than 4 per year as upper limit end-member case. Most events are expected on the Tharsis shield, but minor seismic centers are expected south of Hellas and north of Utopia Planitia.

  14. The spatial distribution of shocked gas in the Orion nebula

    Science.gov (United States)

    Beck, S. C.; Beckwith, S.

    1983-01-01

    Observations of the spatial distribution of extinction and excitation temperature toward the molecular hydrogen emission in the Orion molecular cloud OMC-1 are presented. Most, although not all, of the observed structure in the near-infrared line intensities results from variations in the column density of vibrationally excited H2 and is not due to variable extinction or temperature. The extinction toward the center of the emission region is between 1 and 2 mag at 4712/cm, the frequency of the v = 1-0 S(1) line, but increases toward the edges. The lack of emission from the eastern part of the nebula may result from increased extinction in that direction. Variations in the extinction temperature are less than the observational uncertainties of + or - 200 K at all but one position observed. Therefore, the excitation temperature of the hydrogen molecules is probably not a strong function of either the shock velocity or the density of the gas. Observations of the v = 3-2 S(3) line in the direction of strongest emission indicate the presence of gas temperatures about 2700 K and place constraints on the column density of gas which is at higher temperature.

  15. Landslide characteristics and spatial distribution in the Rwenzori Mountains, Uganda

    Science.gov (United States)

    Jacobs, Liesbet; Dewitte, Olivier; Poesen, Jean; Maes, Jan; Mertens, Kewan; Sekajugo, John; Kervyn, Matthieu

    2017-10-01

    In many landslide-prone regions, data on landslide characteristics remain poor or inexistent. This is also the case for the Rwenzori Mountains, located on the border of Uganda and the DR Congo. There, landslides frequently occur and cause fatalities and substantial damage to private property and infrastructure. In this paper, we present the results of a field inventory performed in three representative study areas covering 114 km2. A total of 371 landslides were mapped and analyzed for their geomorphological characteristics and their spatial distribution. The average landslide areas varied from less than 0.3 ha in the gneiss-dominated highlands to >1 ha in the rift alluvium of the lowlands. Large landslides (>1.5 ha) are well represented while smaller landslides (slides in gneiss and of deep rotational soil slides in the rift alluvium is observed. Slope angle is the main controlling topographic factor for landslides with the highest landslide concentrations for slope angles above 25-30° in the highlands and 10-15° in the lowlands. The undercutting of slopes by rivers and excavations for construction are important preparatory factors. Rainfall-triggered landslides are the most common in the area, however in the zones of influence of the last two major earthquakes (1966: Mw = 6.6 and 1994: Mw = 6.2), 12 co-seismic landslides were also observed.

  16. Spatial Distribution of Fungal Communities in an Arable Soil.

    Directory of Open Access Journals (Sweden)

    Julia Moll

    Full Text Available Fungi are prominent drivers of ecological processes in soils, so that fungal communities across different soil ecosystems have been well investigated. However, for arable soils taxonomically resolved fine-scale studies including vertical itemization of fungal communities are still missing. Here, we combined a cloning/Sanger sequencing approach of the ITS/LSU region as marker for general fungi and of the partial SSU region for arbuscular mycorrhizal fungi (AMF to characterize the microbiome in different maize soil habitats. Four compartments were analyzed over two annual cycles 2009 and 2010: a ploughed soil in 0-10 cm, b rooted soil in 40-50 cm, c root-free soil in 60-70 cm soil depth and d maize roots. Ascomycota was the most dominant phylum across all compartments. Fungal communities including yeasts and AMF differed strongly between compartments. Inter alia, Tetracladium, the overall largest MOTU (molecular operational taxonomic unit, occurred in all compartments, whereas Trichosporon dominated all soil compartments. Sequences belonging to unclassified Helotiales were forming the most abundant MOTUs exclusively present in roots. This study gives new insights on spatial distribution of fungi and helps to link fungal communities to specific ecological properties such as varying resources, which characterize particular niches of the heterogeneous soil environment.

  17. The discrete additive Weibull distribution: A bathtub-shaped hazard for discontinuous failure data

    International Nuclear Information System (INIS)

    Bebbington, Mark; Lai, Chin-Diew; Wellington, Morgan; Zitikis, Ričardas

    2012-01-01

    Although failure data are usually treated as being continuous, they may have been collected in a discrete manner, or in fact be discrete in nature. Reliability models with bathtub-shaped hazard rate are fundamental to the concepts of burn-in and maintenance, but how well do they incorporate discrete data? We explore discrete versions of the additive Weibull distribution, which has the twin virtues of mathematical tractability and the ability to produce bathtub-shaped hazard rate functions. We derive conditions on the parameters for the hazard rate function to be increasing, decreasing, or bathtub shaped. While discrete versions may have the same shaped hazard rate for the same parameter values, we find that when fitted to data the fitted hazard rate shapes can vary between versions. Our results are illustrated using several real-life data sets, and the implications of using continuous models for discrete data discussed.

  18. Spatial and temporal distribution of falciparum malaria in China

    Directory of Open Access Journals (Sweden)

    Lin Hualiang

    2009-06-01

    Full Text Available Abstract Background Falciparum malaria is the most deadly among the four main types of human malaria. Although great success has been achieved since the launch of the National Malaria Control Programme in 1955, malaria remains a serious public health problem in China. This paper aimed to analyse the geographic distribution, demographic patterns and time trends of falciparum malaria in China. Methods The annual numbers of falciparum malaria cases during 1992–2003 and the individual case reports of each clinical falciparum malaria during 2004–2005 were extracted from communicable disease information systems in China Center for Diseases Control and Prevention. The annual number of cases and the annual incidence were mapped by matching them to corresponding province- and county-level administrative units in a geographic information system. The distribution of falciparum malaria by age, gender and origin of infection was analysed. Time-series analysis was conducted to investigate the relationship between the falciparum malaria in the endemic provinces and the imported falciparum malaria in non-endemic provinces. Results Falciparum malaria was endemic in two provinces of China during 2004–05. Imported malaria was reported in 26 non-endemic provinces. Annual incidence of falciparum malaria was mapped at county level in the two endemic provinces of China: Yunnan and Hainan. The sex ratio (male vs. female for the number of cases in Yunnan was 1.6 in the children of 0–15 years and it reached 5.7 in the adults over 15 years of age. The number of malaria cases in Yunnan was positively correlated with the imported malaria of concurrent months in the non-endemic provinces. Conclusion The endemic area of falciparum malaria in China has remained restricted to two provinces, Yunnan and Hainan. Stable transmission occurs in the bordering region of Yunnan and the hilly-forested south of Hainan. The age and gender distribution in the endemic area is

  19. Temporal and spatial distribution characteristics of water resources in Guangdong Province based on a cloud model

    Directory of Open Access Journals (Sweden)

    Qi Zhou

    2015-10-01

    Full Text Available With a focus on the difficulty of quantitatively describing the degree of nonuniformity of temporal and spatial distributions of water resources, quantitative research was carried out on the temporal and spatial distribution characteristics of water resources in Guangdong Province from 1956 to 2000 based on a cloud model. The spatial variation of the temporal distribution characteristics and the temporal variation of the spatial distribution characteristics were both analyzed. In addition, the relationships between the numerical characteristics of the cloud model of temporal and spatial distributions of water resources and precipitation were also studied. The results show that, using a cloud model, it is possible to intuitively describe the temporal and spatial distribution characteristics of water resources in cloud images. Water resources in Guangdong Province and their temporal and spatial distribution characteristics are differentiated by their geographic locations. Downstream and coastal areas have a larger amount of water resources with greater uniformity and stronger stability in terms of temporal distribution. Regions with more precipitation possess larger amounts of water resources, and years with more precipitation show greater nonuniformity in the spatial distribution of water resources. The correlation between the nonuniformity of the temporal distribution and local precipitation is small, and no correlation is found between the stability of the nonuniformity of the temporal and spatial distributions of water resources and precipitation. The amount of water resources in Guangdong Province shows an increasing trend from 1956 to 2000, the nonuniformity of the spatial distribution of water resources declines, and the stability of the nonuniformity of the spatial distribution of water resources is enhanced.

  20. LEADER: fast estimates of asteroid shape elongation and spin latitude distributions from scarce photometry

    Science.gov (United States)

    Nortunen, H.; Kaasalainen, M.

    2017-12-01

    Context. Many asteroid databases with lightcurve brightness measurements (e.g. WISE, Pan-STARRS1) contain enormous amounts of data for asteroid shape and spin modelling. While lightcurve inversion is not plausible for individual targets with scarce data, it is possible for large populations with thousands of asteroids, where the distributions of the shape and spin characteristics of the populations are obtainable. Aims: We aim to introduce a software implementation of a method that computes the joint shape elongation p and spin latitude β distributions for a population, with the brightness observations given in an asteroid database. Other main goals are to include a method for performing validity checks of the algorithm, and a tool for a statistical comparison of populations. Methods: The LEADER software package read the brightness measurement data for a user-defined subpopulation from a given database. The observations were used to compute estimates of the brightness variations of the population members. A cumulative distribution function (CDF) was constructed of these estimates. A superposition of known analytical basis functions yielded this CDF as a function of the (shape, spin) distribution. The joint distribution can be reconstructed by solving a linear constrained inverse problem. To test the validity of the method, the algorithm can be run with synthetic asteroid models, where the shape and spin characteristics are known, and by using the geometries taken from the examined database. Results: LEADER is a fast and robust software package for solving shape and spin distributions for large populations. There are major differences in the quality and coverage of measurements depending on the database used, so synthetic simulations are always necessary before a database can be reliably used. We show examples of differences in the results when switching to another database.

  1. Spatial distribution of Corvidae in transformed landscapes of Zhytomyr region

    Directory of Open Access Journals (Sweden)

    A. V. Matsyura

    2016-03-01

    Full Text Available The spatial distribution and abundance of Corvidae species was studied in Zhytomyr region with a focus on rural and urban differences in the studied parameters. We selected Rook (Corvus frugilegus L., Western Jackdaw (C. monedula L., Hooded Crow (C. cornix L., Eurasian Magpie (Pica pica L., Eurasian Jay (Garrulus glandarius L., and Common Raven (Corvus corax L.. All observations were made during 2009–2012. During the study period some 38 survey paths of more than 8,000 km were surveyed in 21 settlements of Zhytomyr region, among them 13 were in Zhytomyr city. The aim of our study was to establish the number and density of Corvidae in different seasons in the settlements of Zhytomyr region along a rural-urban gradient. The average density of Rooks was 55.9 ind./km2. We also found a strong correlation between Rook density and the rural-urban gradient and observed that the number of Rooks wintering in cities significantly increased due to the influx from villages. The peak number of Rooks in villages was registered in the breeding and post-breeding season while in the cities it was high in winter and during the spring migration. The average density of Eurasian Magpie in the study area was 8.7 ind./km2 and had a weak correlation with the urban-rural gradient. The density of Eurasian Magpies in urban areas differs significantly only from the density of birds in villages with a population of ca. 1,000 people. The density of Magpies varied insignificantly within a narrow range during the three years of research, remaining relatively stable, which suggests that the species successfully adjusts to conditions in transformed landscapes. The urban-rural gradient significantly affects the density of Hooded Crows. The average density of birds in towns was 6.6 ind./km2. In breeding period the urban birds had a low density and rural crows, on the contrary, had a high density, the density of birds in the nesting period was greater than in autumn and winter

  2. Are fractal dimensions of the spatial distribution of mineral deposits meaningful?

    Science.gov (United States)

    Raines, G.L.

    2008-01-01

    It has been proposed that the spatial distribution of mineral deposits is bifractal. An implication of this property is that the number of deposits in a permissive area is a function of the shape of the area. This is because the fractal density functions of deposits are dependent on the distance from known deposits. A long thin permissive area with most of the deposits in one end, such as the Alaskan porphyry permissive area, has a major portion of the area far from known deposits and consequently a low density of deposits associated with most of the permissive area. On the other hand, a more equi-dimensioned permissive area, such as the Arizona porphyry permissive area, has a more uniform density of deposits. Another implication of the fractal distribution is that the Poisson assumption typically used for estimating deposit numbers is invalid. Based on datasets of mineral deposits classified by type as inputs, the distributions of many different deposit types are found to have characteristically two fractal dimensions over separate non-overlapping spatial scales in the range of 5-1000 km. In particular, one typically observes a local dimension at spatial scales less than 30-60 km, and a regional dimension at larger spatial scales. The deposit type, geologic setting, and sample size influence the fractal dimensions. The consequence of the geologic setting can be diminished by using deposits classified by type. The crossover point between the two fractal domains is proportional to the median size of the deposit type. A plot of the crossover points for porphyry copper deposits from different geologic domains against median deposit sizes defines linear relationships and identifies regions that are significantly underexplored. Plots of the fractal dimension can also be used to define density functions from which the number of undiscovered deposits can be estimated. This density function is only dependent on the distribution of deposits and is independent of the

  3. Spatial linear flows of finite length with nonuniform intensity distribution

    Directory of Open Access Journals (Sweden)

    Mikhaylov Ivan Evgrafovich

    2014-02-01

    Full Text Available Irrotational flows produced by spatial linear flows of finite length with different uneven lows of discharge over the flow length are represented in cylindrical coordinate system. Flows with the length 2a are placed in infinite space filled with ideal (inviscid fluid. In “А” variant discharge is fading linearly downward along the length of the flow. In “B” variant in upper half of the flow (length a discharge is fading linearly downward, in lower half of the flow discharge is fading linearly from the middle point to lower end. In “C” variant discharge of the flow is growing linearly from upper and lower ends to middle point.Equations for discharge distribution along the length of the flow are provided for each variant. Equations consist of two terms and include two dimensional parameters and current coordinate that allows integrating on flow length. Analytical expressions are derived for speed potential functions and flow speed components for flow speeds produced by analyzed flows. These analytical expressions consist of dimensional parameters of discharge distribution patterns along the length of the flow. Flow lines equation (meridional sections of flow surfaces for variants “A”, “B”, “C” is unsolvable in quadratures. Flow lines plotting is proposed to be made by finite difference method. Equations for flow line plotting are provided for each variant. Calculations of these equations show that the analyzed flows have the following flow lines: “A” has confocal hyperbolical curves, “B” and “C” have confocal hyperboles. Flow surfaces are confocal hyperboloids produced by rotation of these hyperboles about the axis passing through the flows. In “A” variant the space filled with fluid is separated by vividly horizontal flow surface in two parts. In upper part that includes the smaller part of the flow length flow lines are oriented downward, in lower part – upward. The equation defining coordinate of

  4. Temporal and spatial distribution of high energy electrons at Jupiter

    Science.gov (United States)

    Jun, I.; Garrett, H. B.; Ratliff, J. M.

    2003-04-01

    Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EPD) were used to study the high energy electron environment in the Jovian magnetosphere, especially in the region between 8 to 18 Rj (1 Rj = 1 Jovian radius = 71,400 km). 10-minute averages of the EPD data collected between Jupiter orbit insertion (JOI) in 1995 and the orbit number 33 (I33) in 2002 form an extensive dataset, which has been extremely useful to observe temporal and spatial variability of the Jovian high energy electron environment. The count rates of the EPD electron channels (0.174, 0.304, 0.527, 1.5, 2.0, and 11 MeV) were grouped into 0.5 Rj or 0.5 L bins and analyzed statistically. The results indicate that: (1) a log-normal Gaussian distribution well describes the statistics of the high energy electron environment (for example, electron differential fluxes) in the Jovian magnetosphere, in the region studied here; (2) the high energy electron environments inferred by the Galileo EPD measurements are in a close agreement with the data obtained using the Divine model, which was developed more than 30 years ago from Pioneer 10, 11 and Voyager 1, 2 data; (3) the data are better organized when plotted against magnetic radial parameter L than Rj; (4) the standard deviations of the 0.174, 0.304, 0.527 MeV channel count rates are larger than those of the 1.5, 2.0, 11 MeV count rates in 12 Rj. These observations are very helpful to understand short- and long-term, and local variability of the Jovian high energy electron environment, and are discussed in detail.

  5. LEACHED SOILS IN SLOVENIA: PEDOLOGICAL PROPERTIES, SPATIAL DISTRIBUTION AND CLASSIFICATION

    Directory of Open Access Journals (Sweden)

    Rok TURNIŠKI

    2018-04-01

    Full Text Available Eluvial-illuvial processes plays key role in pedogenesis, especially in the development of leached soils. As reported in Slovenian soil map 1 : 25.000 leached soils cover 2,3 % of Slovenian territory. They occur on different parent materials, mostly on flat relief preserved from erosion and colluvial processes. The aim of our study is the evaluation of their morpohological, physical and chemical properties, spatial distribution and dependency on soil forming factors, especially on parent material. Pedological properties are demonstrated according to analytical and descriptive data of 49 leached soils from the pedological base of Soil Information System of Slovenia. Obvious leaching processes are clearly recognized in almost all profiles of leached soils. Eluvial horizon in comparison to illuvial horizon has lower pH value, which is in average 4,4 and 4,6 for E and Bt horizon respectively, brighter color, lower base saturation (in average for 16,6 % and lower CEC (in average for 5,5 mmolc 100 g -1 soil. On average ratio of clay content between illuvial and eluvial horizon is 1,63. In the 75 % of all studied leached soils this ratio is above 1,38. After evaluation, according to WRB classification, an argic horizon is identified only in 40 soil profiles, while other 9 profiles do not match criteria of sufficient textural differentiation or there is not enough data to classify them. Detailed overview of the WRB criteria for argic horizons (cation exchange capacity of clay fraction and base saturation in argic horizons reveals that Luvisols and Alisols are the most widespread groups in Slovenia among leached soil. Against expectations based on different references, we do not determined Acrisols within Soil Map Database.

  6. FUEL3-D: A Spatially Explicit Fractal Fuel Distribution Model

    Science.gov (United States)

    Russell A. Parsons

    2006-01-01

    Efforts to quantitatively evaluate the effectiveness of fuels treatments are hampered by inconsistencies between the spatial scale at which fuel treatments are implemented and the spatial scale, and detail, with which we model fire and fuel interactions. Central to this scale inconsistency is the resolution at which variability within the fuel bed is considered. Crown...

  7. Spatial patterns of zooplankton distribution and abundance in ...

    African Journals Online (AJOL)

    Spatial patterns and abundance of zooplankton in aquatic habitats are important determinants for production of fish species, invertebrates and availability of phytoplankton. Weekly monitoring for zooplankton abundance was conducted in Shirati Bay, Lake Victoria, to explore their spatial patterns in relation to phytoplankton, ...

  8. Spatial distribution of tsetse flies in some areas within western ...

    African Journals Online (AJOL)

    Accurate identification of tsetse fly endemic-foci using spatially explicit maps could be important in the strategic control of tsetse flies. This survey presents spatially explicit maps of tsetse flies in some tsetse fly-endemic areas in the Western, Eastern and Northern Regions of Ghana. Field samplings for tsetse flies using ...

  9. Measurement of shape property distributions of quartzite aggregate from different crushers using 3D laser scanning system

    CSIR Research Space (South Africa)

    Mgangira, MB

    2016-01-01

    Full Text Available the differences between individual aggregates. It was possible to quantify differences in particle shape characteristics at the small particle scale and aggregate shape distributions between the different types of crushers and possible influence of particle sizes...

  10. Prediction of bulk powder flow performance using comprehensive particle size and particle shape distributions.

    Science.gov (United States)

    Yu, Weili; Muteki, Koji; Zhang, Lin; Kim, Gloria

    2011-01-01

    The purpose of this study is to establish a modeling approach that can be used to predict bulk powder flowability of pharmaceutical materials from their particle size and shape distributions. To build and validate the model, 23 commonly used pharmaceutical excipients and 38 binary blends were fully characterized for their particle size and shape distributions. The particle size and shape of each sample was characterized by multiple descriptors to fully reflect their morphological characteristics. The flow properties of these materials were analyzed using the Schulze Ring Shear Tester at a fixed humidity condition. A partial least squares (PLS) approach was used to build the mathematical model. Several different modeling approaches were attempted and the best method was identified as using a combination of formulation composition and particle size and shape distributions of single-component powder systems. The PLS model was shown to provide excellent predictions of powder flow function coefficient (FFC) of up to approximately 20. The results also revealed that both particle size and shape play an important role in determining the powder flow behavior. Copyright © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

  11. Laser beam shaping limitations for laboratory simulation of turbulence using a phase-only spatial light modulator

    CSIR Research Space (South Africa)

    Litvin, IA

    2007-09-01

    Full Text Available phase screens. In this work the authors investigate the limitation of laser beam shaping with a phase-only spatial light modulator for the simulation of dynamic and pseudo-random turbulence in the laboratory. Findings state that there are regimes where...

  12. Spatial and temporal distribution of ionospheric currents-4: altitude ...

    African Journals Online (AJOL)

    (a) The continuous distribution of current density model reproduces the altitude distribution parameters of EEJ current density very well, (b) the altitude distribution parameters of EEJ current density in India and Peru are not significantly different and (c) The altitude distribution parameters of EEJ current density from rockets ...

  13. Vortex distribution in small star-shaped Mo{sub 80}Ge{sub 20} plate

    Energy Technology Data Exchange (ETDEWEB)

    Vu, The Dang, E-mail: vu-dang@pe.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Department of Physics and Electronics, University of Sciences, Vietnam National University HCMC (Viet Nam); Matsumoto, Hitoshi; Miyoshi, Hiroki [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Huy, Ho Thanh [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Department of Physics and Electronics, University of Sciences, Vietnam National University HCMC (Viet Nam); Shishido, Hiroaki [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Kato, Masaru [Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Department of Mathematical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Ishida, Takekazu [Department of Physics and Electronics, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2017-02-15

    Highlights: • We found the general feature of vortex configuration in small star-shaped Mo{sub 80}Ge{sub 20} plates such as the appearance of symmetric line, the rule of shell filling and the existence of a magic number in both theoretical predictions and experimental results. • We found that the vortex distribution in a concave decagon tends to adapt to one of the five symmetric axes of the star-shaped plate expected in confining vortices in a restricted sample geometry. • The numerical results of Ginzburg–Landau equation confirmed that the filling rules for a vortex configuration and the existence of a magic number for small star-shaped plates are in good agreement with experiment results. - Abstract: We investigated vortex states in small star-shaped Mo{sub 80}Ge{sub 20} plates both theoretically and experimentally. The numerical calculations of the Ginzburg–Landau equation have been carried out with the aid of the finite element method, which is convenient to treat an arbitrarily shaped superconductor. The experimental results were observed by using a scanning SQUID microscope. Through systematic measurements, we figured out how vortices form symmetric configuration with increasing the magnetic field. The vortex distribution tends to adapt to one of five mirror symmetric lines when vortices were located at the five triangular horns of a star-shaped plate. The crystalline homogeneity of a sample was confirmed by the X-ray diffraction and the superconducting properties so that vortices are easily able to move for accommodating vortices in the geometric symmetry of the star-shaped plate. The experimental vortex configurations obtained for a star-shaped plate are in good agreement with theoretical predictions from the nonlinear Ginzburg–Landau equation.

  14. Spatial Distribution of Infection Risk of SARS Transmission in a Hospital Ward

    DEFF Research Database (Denmark)

    Qian, Hua; Li, Yuguo; Nielsen, Peter V.

    2009-01-01

    The classical Wells-Riley model for predicting risk of airborne transmission of diseases assumes a uniform spatial distribution of the infected cases in an enclosed space. A new mathematical model is developed here for predicting the spatial distribution of infection risk of airborne transmitted ......, such as inpatients in a hospital ward, passengers in an airplane etc....

  15. Development of a hemispherical rotational modulation collimator system for imaging spatial distribution of radiation sources

    Science.gov (United States)

    Na, M.; Lee, S.; Kim, G.; Kim, H. S.; Rho, J.; Ok, J. G.

    2017-12-01

    Detecting and mapping the spatial distribution of radioactive materials is of great importance for environmental and security issues. We design and present a novel hemispherical rotational modulation collimator (H-RMC) system which can visualize the location of the radiation source by collecting signals from incident rays that go through collimator masks. The H-RMC system comprises a servo motor-controlled rotating module and a hollow heavy-metallic hemisphere with slits/slats equally spaced with the same angle subtended from the main axis. In addition, we also designed an auxiliary instrument to test the imaging performance of the H-RMC system, comprising a high-precision x- and y-axis staging station on which one can mount radiation sources of various shapes. We fabricated the H-RMC system which can be operated in a fully-automated fashion through the computer-based controller, and verify the accuracy and reproducibility of the system by measuring the rotational and linear positions with respect to the programmed values. Our H-RMC system may provide a pivotal tool for spatial radiation imaging with high reliability and accuracy.

  16. A temperature-compensated high spatial resolution distributed strain sensor

    International Nuclear Information System (INIS)

    Belal, Mohammad; Cho, Yuh Tat; Ibsen, Morten; Newson, Trevor P

    2010-01-01

    We propose and demonstrate a scheme which utilizes the temperature dependence of spontaneous Raman scattering to provide temperature compensation for a high spatial resolution Brillouin frequency-based strain sensor

  17. Comparison of Two Methods Used to Model Shape Parameters of Pareto Distributions

    Science.gov (United States)

    Liu, C.; Charpentier, R.R.; Su, J.

    2011-01-01

    Two methods are compared for estimating the shape parameters of Pareto field-size (or pool-size) distributions for petroleum resource assessment. Both methods assume mature exploration in which most of the larger fields have been discovered. Both methods use the sizes of larger discovered fields to estimate the numbers and sizes of smaller fields: (1) the tail-truncated method uses a plot of field size versus size rank, and (2) the log-geometric method uses data binned in field-size classes and the ratios of adjacent bin counts. Simulation experiments were conducted using discovered oil and gas pool-size distributions from four petroleum systems in Alberta, Canada and using Pareto distributions generated by Monte Carlo simulation. The estimates of the shape parameters of the Pareto distributions, calculated by both the tail-truncated and log-geometric methods, generally stabilize where discovered pool numbers are greater than 100. However, with fewer than 100 discoveries, these estimates can vary greatly with each new discovery. The estimated shape parameters of the tail-truncated method are more stable and larger than those of the log-geometric method where the number of discovered pools is more than 100. Both methods, however, tend to underestimate the shape parameter. Monte Carlo simulation was also used to create sequences of discovered pool sizes by sampling from a Pareto distribution with a discovery process model using a defined exploration efficiency (in order to show how biased the sampling was in favor of larger fields being discovered first). A higher (more biased) exploration efficiency gives better estimates of the Pareto shape parameters. ?? 2011 International Association for Mathematical Geosciences.

  18. A SVR Learning Based Sensor Placement Approach for Nonlinear Spatially Distributed Systems

    Directory of Open Access Journals (Sweden)

    Xian-xia Zhang

    2016-01-01

    Full Text Available Many industrial processes are inherently distributed in space and time and are called spatially distributed dynamical systems (SDDSs. Sensor placement affects capturing the spatial distribution and then becomes crucial issue to model or control an SDDS. In this study, a new data-driven based sensor placement method is developed. SVR algorithm is innovatively used to extract the characteristics of spatial distribution from a spatiotemporal data set. The support vectors learned by SVR represent the crucial spatial data structure in the spatiotemporal data set, which can be employed to determine optimal sensor location and sensor number. A systematic sensor placement design scheme in three steps (data collection, SVR learning, and sensor locating is developed for an easy implementation. Finally, effectiveness of the proposed sensor placement scheme is validated on two spatiotemporal 3D fuzzy controlled spatially distributed systems.

  19. Exponentiated Weibull distribution approach based inflection S-shaped software reliability growth model

    Directory of Open Access Journals (Sweden)

    B.B. Sagar

    2016-09-01

    Full Text Available The aim of this paper was to estimate the number of defects in software and remove them successfully. This paper incorporates Weibull distribution approach along with inflection S-shaped Software Reliability Growth Models (SRGM. In this combination two parameter Weibull distribution methodology is used. Relative Prediction Error (RPE is calculated to predict the validity criterion of the developed model. Experimental results on actual data from five data sets are compared with two other existing models, which expose that the proposed software reliability growth model predicts better estimation to remove the defects. This paper presents best software reliability growth model with including feature of both Weibull distribution and inflection S-shaped SRGM to estimate the defects of software system, and provide help to researchers and software industries to develop highly reliable software products.

  20. Combination of panoramic and fluorescence endoscopic images to obtain tumor spatial distribution information useful for bladder cancer detection

    Science.gov (United States)

    Olijnyk, S.; Hernández Mier, Y.; Blondel, W. C. P. M.; Daul, C.; Wolf, D.; Bourg-Heckly, G.

    2007-07-01

    Bladder cancer is widely spread. Moreover, carcinoma in situ can be difficult to diagnose as it may be difficult to see, and become invasive in 50 % of case. Non invasive diagnosis methods like photodynamic or autofluorescence endoscopy allow enhancing sensitivity and specificity. Besides, bladder tumors can be multifocal. Multifocality increases the probability of recurrence and infiltration into bladder muscle. Analysis of spatial distribution of tumors could be used to improve diagnosis. We explore the feasibility to combine fluorescence and spatial information on phantoms. We developed a system allowing the acquisition of consecutive images under white light or UV excitation alternatively and automatically along the video sequence. We also developed an automatic image processing algorithm to build a partial panoramic image from a cystoscopic sequence of images. Fluorescence information is extracted from wavelength bandpass filtered images and superimposed over the cartography. Then, spatial distribution measures of fluorescent spots can be computed. This cartography can be positioned on a 3D generic shape of bladder by selecting some reference points. Our first results on phantoms show that it is possible to obtain cartography with fluorescent spots and extract quantitative information of their spatial distribution on a "wide" field of view basis.

  1. Effect of Lithium Ions on Copper Nanoparticle Size, Shape, and Distribution

    Directory of Open Access Journals (Sweden)

    Kyung-Deok Jang

    2012-01-01

    Full Text Available Copper nanoparticles were synthesized using lithium ions to increase the aqueous electrical conductivity of the solution and precisely control the size, shape, and size distribution of the particles. In this study, the conventional approach of increasing particle size by the concentration of copper ions and PGPPE in a copper chloride solution was compared to increasing the concentration of lithium chloride when the copper chloride concentration was held constant. Particle size and shape were characterized by TEM, and the size distribution of the particles at different concentrations was obtained by particle size analysis. Increasing the concentration of copper ion in the solution greatly increased the aqueous electric conductivity and the size of the particles but led to a wide size distribution ranging from 150 nm to 400 nm and rough particle morphology. The addition of lithium ions increased the size of the particles, but maintains them in a range of 250 nm. In addition the particles exhibited spherical shape as determined by TEM. The addition of lithium ions to the solution has the potential to synthesize nanoparticles with optimal characteristics for printing applications by maintaining a narrow size range and spherical shape.

  2. Revealing the spiral arms through radial migration and the shape of the metallicity distribution function

    Science.gov (United States)

    Martinez-Medina, L. A.; Pichardo, B.; Moreno, E.; Peimbert, A.

    2016-11-01

    Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterize some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.

  3. Simultaneous reconstruction of outer boundary shape and conductivity distribution in electrical impedance tomography

    KAUST Repository

    Hyvönen, Nuutti

    2016-01-05

    The simultaneous retrieval of the exterior boundary shape and the interior admittivity distribution of an examined body in electrical impedance tomography is considered. The reconstruction method is built for the complete electrode model and it is based on the Frechet derivative of the corresponding current-to-voltage map with respect to the body shape. The reconstruction problem is cast into the Bayesian framework, and maximum a posteriori estimates for the admittivity and the boundary geometry are computed. The feasibility of the approach is evaluated by experimental data from water tank measurements.

  4. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system

    International Nuclear Information System (INIS)

    Liu, Jingqing; Chen, Huanyu; Yao, Lingdan; Wei, Zongyuan; Lou, Liping; Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda; Hu, Baolan; Zhou, Xiaoyan

    2016-01-01

    Highlights: • First investigating the spatial distribution of pollutants in pipe-scale. • Spatial distribution of heavy metals indicated their sources were different. • Three main factors effete the distribution of pollutants. • Organic deposits mainly included microbial and microalgae metabolites. - Abstract: In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600 mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography–Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better.

  5. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jingqing [College of Engineering and Architecture, Zhejiang University, Hangzhou 310058 (China); Chen, Huanyu [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Binhai Industrial Technology Research Institute of Zhejiang University, Tianjin 300000 (China); Yao, Lingdan; Wei, Zongyuan [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Lou, Liping, E-mail: loulp@zju.edu.cn [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda [Environmental Protection Agency, Office of Research and Development, NRMRL, Cincinnati, OH 45220 (United States); Hu, Baolan [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Zhou, Xiaoyan [Shaoxing Water Environmental Science Institute Co. Ltd, Zhejiang 312000 (China)

    2016-11-05

    Highlights: • First investigating the spatial distribution of pollutants in pipe-scale. • Spatial distribution of heavy metals indicated their sources were different. • Three main factors effete the distribution of pollutants. • Organic deposits mainly included microbial and microalgae metabolites. - Abstract: In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600 mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography–Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better.

  6. The Shape of Human Navigation: How Environmental Geometry Is Used in Maintenance of Spatial Orientation

    Science.gov (United States)

    Kelly, Jonathan W.; McNamara, Timothy P.; Bodenheimer, Bobby; Carr, Thomas H.; Rieser, John J.

    2008-01-01

    The role of environmental geometry in maintaining spatial orientation was measured in immersive virtual reality using a spatial updating task (requiring maintenance of orientation during locomotion) within rooms varying in rotational symmetry (the number of room orientations providing the same perspective). Spatial updating was equally good in…

  7. Assessment of Rainfall-induced Landslide Potential and Spatial Distribution

    Science.gov (United States)

    Chen, Yie-Ruey; Tsai, Kuang-Jung; Chen, Jing-Wen; Chiang, Jie-Lun; Hsieh, Shun-Chieh; Chue, Yung-Sheng

    2016-04-01

    Recently, due to the global climate change, most of the time the rainfall in Taiwan is of short duration but with high intensity. Due to Taiwan's steep terrain, rainfall-induced landslides often occur and lead to human causalities and properties loss. Taiwan's government has invested huge reconstruction funds to the affected areas. However, after rehabilitation they still face the risk of secondary sediment disasters. Therefore, this study assesses rainfall-induced (secondary) landslide potential and spatial distribution in watershed of Southern Taiwan under extreme climate change. The study areas in this research are Baolai and Jianshan villages in the watershed of the Laonongxi River Basin in the Southern Taiwan. This study focused on the 3 years after Typhoon Morakot (2009 to 2011). During this period, the study area experienced six heavy rainfall events including five typhoons and one heavy rainfall. The genetic adaptive neural network, texture analysis and GIS were implemented in the analysis techniques for the interpretation of satellite images and to obtain surface information and hazard log data and to analyze land use change. A multivariate hazards evaluation method was applied to quantitatively analyze the weights of various natural environmental and slope development hazard factors. Furthermore, this study established a slope landslide potential assessment model and depicted a slope landslide potential diagram by using the GIS platform. The interaction between (secondary) landslide mechanism, scale, and location was analyzed using association analysis of landslide historical data and regional environmental characteristics. The results of image classification before and after six heavy rainfall events show that the values of coefficient of agreement are at medium-high level. By multivariate hazards evaluation method, geology and the effective accumulative rainfall (EAR) are the most important factors. Slope, distance from fault, aspect, land disturbance

  8. Spatial distribution of soil erosion and suspended sediment ...

    Indian Academy of Sciences (India)

    extension modules (spatial analysis, hydrologic model, 3D Analyst, Network Analyst), and the Object-Oriented Programming Language. (Avenue). This data consists of slope, area, aver- age elevation, roughness, CN value, etc. In addi- tion, GIS can also determine the flow direction, the accumulated discharge, the main ...

  9. 5 Spatial Distribution of Nematodes at Organic.cdr

    African Journals Online (AJOL)

    user

    live in the thin films of water surrounding soil particles because water aids their mobility (Freckman ... Geostatistics can be used to analyse and quantify spatial autocorrelation by distance and direction (Evans et al., 1999). Geostatistical analysis in previous studies has shown that field-scale autocorrelation in nematode ...

  10. A Spatial Analysis of Population Distribution and Housing Patterns ...

    African Journals Online (AJOL)

    ... administered using the stratified randomsampling technique. The study area was divided into three major zones based on existing quarters in Abraka. The Pearson product moment correlation was used to measure the strength of the relationship between the spatial patterns of population and housing in Abraka. Solutions ...

  11. Analysis of spatial distribution of land cover maps accuracy

    Science.gov (United States)

    Khatami, R.; Mountrakis, G.; Stehman, S. V.

    2017-12-01

    Land cover maps have become one of the most important products of remote sensing science. However, classification errors will exist in any classified map and affect the reliability of subsequent map usage. Moreover, classification accuracy often varies over different regions of a classified map. These variations of accuracy will affect the reliability of subsequent analyses of different regions based on the classified maps. The traditional approach of map accuracy assessment based on an error matrix does not capture the spatial variation in classification accuracy. Here, per-pixel accuracy prediction methods are proposed based on interpolating accuracy values from a test sample to produce wall-to-wall accuracy maps. Different accuracy prediction methods were developed based on four factors: predictive domain (spatial versus spectral), interpolation function (constant, linear, Gaussian, and logistic), incorporation of class information (interpolating each class separately versus grouping them together), and sample size. Incorporation of spectral domain as explanatory feature spaces of classification accuracy interpolation was done for the first time in this research. Performance of the prediction methods was evaluated using 26 test blocks, with 10 km × 10 km dimensions, dispersed throughout the United States. The performance of the predictions was evaluated using the area under the curve (AUC) of the receiver operating characteristic. Relative to existing accuracy prediction methods, our proposed methods resulted in improvements of AUC of 0.15 or greater. Evaluation of the four factors comprising the accuracy prediction methods demonstrated that: i) interpolations should be done separately for each class instead of grouping all classes together; ii) if an all-classes approach is used, the spectral domain will result in substantially greater AUC than the spatial domain; iii) for the smaller sample size and per-class predictions, the spectral and spatial domain

  12. Distributed multi-criteria model evaluation and spatial association analysis

    Science.gov (United States)

    Scherer, Laura; Pfister, Stephan

    2015-04-01

    Model performance, if evaluated, is often communicated by a single indicator and at an aggregated level; however, it does not embrace the trade-offs between different indicators and the inherent spatial heterogeneity of model efficiency. In this study, we simulated the water balance of the Mississippi watershed using the Soil and Water Assessment Tool (SWAT). The model was calibrated against monthly river discharge at 131 measurement stations. Its time series were bisected to allow for subsequent validation at the same gauges. Furthermore, the model was validated against evapotranspiration which was available as a continuous raster based on remote sensing. The model performance was evaluated for each of the 451 sub-watersheds using four different criteria: 1) Nash-Sutcliffe efficiency (NSE), 2) percent bias (PBIAS), 3) root mean square error (RMSE) normalized to standard deviation (RSR), as well as 4) a combined indicator of the squared correlation coefficient and the linear regression slope (bR2). Conditions that might lead to a poor model performance include aridity, a very flat and steep relief, snowfall and dams, as indicated by previous research. In an attempt to explain spatial differences in model efficiency, the goodness of the model was spatially compared to these four phenomena by means of a bivariate spatial association measure which combines Pearson's correlation coefficient and Moran's index for spatial autocorrelation. In order to assess the model performance of the Mississippi watershed as a whole, three different averages of the sub-watershed results were computed by 1) applying equal weights, 2) weighting by the mean observed river discharge, 3) weighting by the upstream catchment area and the square root of the time series length. Ratings of model performance differed significantly in space and according to efficiency criterion. The model performed much better in the humid Eastern region than in the arid Western region which was confirmed by the

  13. Can Bt maize change the spatial distribution of predator Cycloneda ...

    African Journals Online (AJOL)

    The aggregation index (variance/mean ratio, Morisita index, and exponent k of the negative binomial distribution) and Chi-square fit of the observed and expected values to the theoretical frequency distribution (Poisson, binomial, and negative binomial positive) revealed that, in both cultivars, the adults of C. sanguinea ...

  14. Using spatial principles to optimize distributed computing for enabling the physical science discoveries.

    Science.gov (United States)

    Yang, Chaowei; Wu, Huayi; Huang, Qunying; Li, Zhenlong; Li, Jing

    2011-04-05

    Contemporary physical science studies rely on the effective analyses of geographically dispersed spatial data and simulations of physical phenomena. Single computers and generic high-end computing are not sufficient to process the data for complex physical science analysis and simulations, which can be successfully supported only through distributed computing, best optimized through the application of spatial principles. Spatial computing, the computing aspect of a spatial cyberinfrastructure, refers to a computing paradigm that utilizes spatial principles to optimize distributed computers to catalyze advancements in the physical sciences. Spatial principles govern the interactions between scientific parameters across space and time by providing the spatial connections and constraints to drive the progression of the phenomena. Therefore, spatial computing studies could better position us to leverage spatial principles in simulating physical phenomena and, by extension, advance the physical sciences. Using geospatial science as an example, this paper illustrates through three research examples how spatial computing could (i) enable data intensive science with efficient data/services search, access, and utilization, (ii) facilitate physical science studies with enabling high-performance computing capabilities, and (iii) empower scientists with multidimensional visualization tools to understand observations and simulations. The research examples demonstrate that spatial computing is of critical importance to design computing methods to catalyze physical science studies with better data access, phenomena simulation, and analytical visualization. We envision that spatial computing will become a core technology that drives fundamental physical science advancements in the 21st century.

  15. Bat distribution size or shape as determinant of viral richness in african bats.

    Directory of Open Access Journals (Sweden)

    Gaël D Maganga

    Full Text Available The rising incidence of emerging infectious diseases (EID is mostly linked to biodiversity loss, changes in habitat use and increasing habitat fragmentation. Bats are linked to a growing number of EID but few studies have explored the factors of viral richness in bats. These may have implications for role of bats as potential reservoirs. We investigated the determinants of viral richness in 15 species of African bats (8 Pteropodidae and 7 microchiroptera in Central and West Africa for which we provide new information on virus infection and bat phylogeny. We performed the first comparative analysis testing the correlation of the fragmented geographical distribution (defined as the perimeter to area ratio with viral richness in bats. Because of their potential effect, sampling effort, host body weight, ecological and behavioural traits such as roosting behaviour, migration and geographical range, were included into the analysis as variables. The results showed that the geographical distribution size, shape and host body weight have significant effects on viral richness in bats. Viral richness was higher in large-bodied bats which had larger and more fragmented distribution areas. Accumulation of viruses may be related to the historical expansion and contraction of bat species distribution range, with potentially strong effects of distribution edges on virus transmission. Two potential explanations may explain these results. A positive distribution edge effect on the abundance or distribution of some bat species could have facilitated host switches. Alternatively, parasitism could play a direct role in shaping the distribution range of hosts through host local extinction by virulent parasites. This study highlights the importance of considering the fragmentation of bat species geographical distribution in order to understand their role in the circulation of viruses in Africa.

  16. Determinants of the distribution and concentration of biogas production in Germany. A spatial econometric analysis

    International Nuclear Information System (INIS)

    Scholz, Lukas

    2015-01-01

    The biogas production in Germany is characterized by a heterogeneous distribution and the formation of regional centers. In the present study the determinants of the spatial distribution and concentration are analyzed with methods of spatial statistics and spatial econometrics. In addition to the consideration of ''classic'' site factors of agricultural production, the analysis here focuses on the possible relevance of agglomeration effects. The results of the work contribute to a better understanding of the regional distribution and concentration of the biogas production in Germany. [de

  17. Effect of gel texture and sucrose spatial distribution on sweetness perception

    NARCIS (Netherlands)

    Mosca, A.C.; Velde, van de F.; Bult, J.H.F.; Boekel, van M.A.J.S.; Stieger, M.A.

    2012-01-01

    Layered gels differing in mechanical and breakdown properties (soft, medium and hard gels) and in the distribution of sucrose in the matrix (homogeneous and inhomogeneous distributions) were used to investigate the effects of texture and spatial distribution of sucrose on sweetness perception.

  18. Demonstrating the Use of Spatial Optimising Techniques by Means of a Freight Distribution Game.

    Science.gov (United States)

    McKinnon, Alan C.

    1984-01-01

    College seniors in a geography of marketing and distribution course learn about spatial optimizing techniques by participating in a freight distribution game. Students plan the distribution of confectionery from two factories in England to 20 wholesale and retail customers in Scotland. The team that designs the lowest cost system wins. (RM)

  19. Relations between Spatial Distribution, Social Affiliations and Dominance Hierarchy in a Semi-Free Mandrill Population.

    Science.gov (United States)

    Naud, Alexandre; Chailleux, Eloise; Kestens, Yan; Bret, Céline; Desjardins, Dominic; Petit, Odile; Ngoubangoye, Barthélémy; Sueur, Cédric

    2016-01-01

    Although there exist advantages to group-living in comparison to a solitary lifestyle, costs and gains of group-living may be unequally distributed among group members. Predation risk, vigilance levels and food intake may be unevenly distributed across group spatial geometry and certain within-group spatial positions may be more or less advantageous depending on the spatial distribution of these factors. In species characterized with dominance hierarchy, high-ranking individuals are commonly observed in advantageous spatial position. However, in complex social systems, individuals can develop affiliative relationships that may balance the effect of dominance relationships in individual's spatial distribution. The objective of the present study is to investigate how the group spatial distribution of a semi-free ranging colony of Mandrills relates to its social organization. Using spatial observations in an area surrounding the feeding zone, we tested the three following hypothesis: (1) does dominance hierarchy explain being observed in proximity or far from a food patch? (2) Do affiliative associations also explain being observed in proximity or far from a food patch? (3) Do the differences in rank in the group hierarchy explain being co-observed in proximity of a food patch? Our results showed that high-ranking individuals were more observed in proximity of the feeding zone while low-ranking individuals were more observed at the boundaries of the observation area. Furthermore, we observed that affiliative relationships were also associated with individual spatial distributions and explain more of the total variance of the spatial distribution in comparison with dominance hierarchy. Finally, we found that individuals observed at a same moment in proximity of the feeding zone were more likely to be distant in the hierarchy while controlling for maternal kinship, age and sex similarity. This study brings some elements about how affiliative networks and dominance

  20. Relations Between Spatial Distribution, Social Affiliations And Dominance Hierarchy In A Semi-Free Mandrill Population

    Directory of Open Access Journals (Sweden)

    Alexandre eNaud

    2016-05-01

    Full Text Available Although there exist advantages to group-living in comparison to a solitary lifestyle, costs and gains of group-living may be unequally distributed among group members. Predation risk, vigilance levels and food intake may be unevenly distributed across group spatial geometry and certain within-group spatial positions may be more or less advantageous depending on the spatial distribution of these factors. In species characterized with dominance hierarchy, high-ranking individuals are commonly observed in advantageous spatial position. However, in complex social systems, individuals can develop affiliative relationships that may balance the effect of dominance relationships in individual’s spatial distribution. The objective of the present study is to investigate how the group spatial distribution of a semi-free ranging colony of Mandrills relates to its social organization. Using spatial observations in an area surrounding the feeding zone, we tested the three following hypothesis: (1 does dominance hierarchy explain being observed in proximity or far from a food patch? (2 Do affiliative associations also explain being observed in proximity or far from a food patch? (3 Do the differences in rank in the group hierarchy explain being co-observed in proximity of a food patch? Our results showed that high-ranking individuals were more observed in proximity of the feeding zone while low-ranking individuals were more observed at the boundaries of the observation area. Furthermore, we observed that affiliative relationships were also associated with individual spatial distributions and explain more of the total variance of the spatial distribution in comparison with dominance hierarchy. Finally, we found that individuals observed at a same moment in proximity of the feeding zone were more likely to be distant in the hierarchy while controlling for maternal kinship, age and sex similarity. This study brings some elements about how affiliative networks

  1. Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

    Science.gov (United States)

    Egedal, J.; Le, A.; Daughton, W.; Wetherton, B.; Cassak, P. A.; Chen, L.-J.; Lavraud, B.; Torbert, R. B.; Dorelli, J.; Gershman, D. J.; Avanov, L. A.

    2016-10-01

    Supported by a kinetic simulation, we derive an exclusion energy parameter EX providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell demon, only high-energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low-density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low-density separatrix.

  2. Spatial distribution of volatile compounds in epoxy resins for composites

    International Nuclear Information System (INIS)

    Grayson, M.A.; Wolf, C.J.

    1982-01-01

    Precision abrasion mass spectrometry (PAMS) was used to determine the quantitative distribution profile of water in three epoxy resin systems: tetraglycidyl diaminodiphenyl methane (TGDDM) cured with dicyandiamide (DICY), diglycidyl ether of bisphenol A (DGEBA) cured with DICY, and TGDDM cured with diaminodiphenyl sulfone (DDS). The first two resin systems also contain an epoxy cresol novolac. Specimens of the three resins were exposed to a humid environment for 4 to 2000 hours. The water distribution was determined immediately following environmental exposure. Distribution profiles of oxygen, carbon dioxide, and dichloromethane were also measured in the specimens. A brief description of the PAMS apparatus and a discussion of the distribution profiles of the sorbed gases in the three epoxy resin systems as a function of exposure time are given

  3. Spatial distributions of dose enhancement around a gold nanoparticle at several depths of proton Bragg peak

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jihun [Department of Radiation Oncology, Hokkaido University Graduate School of Medicine, Hokkaido University (Japan); Sutherland, Kenneth [Department of Medical Physics, Hokkaido University Graduate School of Medicine, Hokkaido University (Japan); Hashimoto, Takayuki [Department of Radiation Medicine, Hokkaido University Graduate School of Medicine (Japan); Shirato, Hiroki [Department of Radiation Medicine, Hokkaido University Graduate School of Medicine and Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University (Japan); Date, Hiroyuki, E-mail: date@hs.hokudai.ac.jp [Faculty of Health Sciences, Hokkaido University (Japan)

    2016-10-01

    Gold nanoparticles (GNPs) have been recognized as a promising candidate for a radiation sensitizer. A proton beam incident on a GNP can produce secondary electrons, resulting in an enhancement of the dose around the GNP. However, little is known about the spatial distribution of dose enhancement around the GNP, especially in the direction along the incident proton. The purpose of this study is to determine the spatial distribution of dose enhancement by taking the incident direction into account. Two steps of calculation were conducted using the Geant4 Monte Carlo simulation toolkit. First, the energy spectra of 100 and 195 MeV protons colliding with a GNP were calculated at the Bragg peak and three other depths around the peak in liquid water. Second, the GNP was bombarded by protons with the obtained energy spectra. Radial dose distributions were computed along the incident beam direction. The spatial distributions of the dose enhancement factor (DEF) and subtracted dose (D{sub sub}) were then evaluated. The spatial DEF distributions showed hot spots in the distal radial region from the proton beam axis. The spatial D{sub sub} distribution isotropically spread out around the GNP. Low energy protons caused higher and wider dose enhancement. The macroscopic dose enhancement in clinical applications was also evaluated. The results suggest that the consideration of the spatial distribution of GNPs in treatment planning will maximize the potential of GNPs.

  4. Spatial and environmental variation in phyllostomid bat (Chiroptera, Phyllostomidae distribution in Mexico

    Directory of Open Access Journals (Sweden)

    Arriaga–Flores, J. C.

    2018-01-01

    Full Text Available Species’ spatial distribution patterns allow us to understand the establishment of different biotic components in different environmental conditions. This study analyzes the spatial distribution of the Phyllostomidae family in Mexico to identify groups of species that occur in similar sites, the environmental conditions associated with species distribution, and the percent of overlap with human–modified areas. The results suggest six groups of sites with particular species composition. The spatial variation in richness pattern was associated with species tolerance to environmental conditions, such as minimum temperature and tree cover. The convergence between species distribution and modified areas varied per species feeding guild. Insectivorous and nectarivorous bats were sensitive species because they occurred in narrow environmental conditions and their distributions overlapped with areas modified by human activities. The approach implemented here analyzes regional species distributions and estimates their environmental requirements, contributing to the development of optimal conservation strategies for susceptible bat species.

  5. [Spatial distribution characteristics of organic carbon in the soil-plant systems in the Yellow River estuary tidal flat wetland].

    Science.gov (United States)

    Dong, Hong-Fang; Yu, Jun-Bao; Sun, Zhi-Gao; Mu, Xiao-Jie; Chen, Xiao-Bing; Mao, Pei-Li; Wu, Chun-Fa; Guan, Bo

    2010-06-01

    Well-understand the organic carbon status in the Yellow River delta is the most important for studying the biogeochemical processes of the muddy-sandy coastal wetland and ecological restoration. The spatial distribution characteristics and its impact factors of organic carbon in the plant-soil systems of new-born tidal flat wetland in the Yellow River estuary were studied. The results showed that the difference of plant organic carbon content in different plant communities were not obvious, however significant difference of the plant organic carbon density was observed. Moreover, the M-shaped spatial distribution of the plant organic carbon density, which was similar to the plant biomass, was found in the study. The organic carbon contents in top soils were varied from 0.75 to 8.35 g x kg(-1), which was much lower than that in the typical freshwater marsh wetlands ecosystem. The spatial distribution trend of soil organic carbon density was similar to the soil organic carbon. The correlation analysis showed that soil organic carbon density was negatively correlated with pH, and positively correlated with TN, C/N and salinity. However, the correlations of plant organic carbon density with the soil organic carbon density, TN, C/N, pH and salinity were not significant.

  6. The spatial distribution of underage tobacco sales in Los Angeles.

    Science.gov (United States)

    Lipton, Robert; Banerjee, Aniruddha; Levy, David; Manzanilla, Nora; Cochrane, Michelle

    2008-01-01

    Underage tobacco sales is considered a serious public health problem in Los Angeles. Anecdotally, rates have been thought to be quite high. In this paper, using spatial statistical techniques, we describe underage tobacco sales, identifying areas with high levels of sales and hot spots controlling for sociodemographic measures. Six hundred eighty-nine tobacco outlets were investigated throughout the city of Los Angeles in 2001. We consider the factors that explain vendor location of illegal sales of tobacco to underage youth and focus on those areas with especially high rates of illegal sales when controlling for other independent measures. Using data from the census, the LA City Attorney's Office, and public records on school locations in Los Angeles, we employ general least-squares (GLS) estimators in order to avoid biased estimates. vendor location of underage tobacco compliance checks, violators, and nonviolators. Underage tobacco sales in Los Angeles were very high (33.5%) for the entire city in 2001. In many zip codes this rate is considerably higher (60%-100%). When conducting spatial modeling, lower income and ethnicity were strongly associated with increases in underage tobacco sales. Hotspot areas of underage tobacco sales also had much lower mean family income and a much higher percentage of foreign born and greater population density. Spatial techniques were used to better identify areas where vendors sell tobacco to underage youth. Lower income areas were much more likely to both have higher rates of underage tobacco sales and to be a hot spot for such sales. Population density is also significantly associated with underage tobacco sales. The study's limitations are noted.

  7. Intelligent estimation of spatially distributed soil physical properties

    Science.gov (United States)

    Iwashita, F.; Friedel, M.J.; Ribeiro, G.F.; Fraser, Stephen J.

    2012-01-01

    Spatial analysis of soil samples is often times not possible when measurements are limited in number or clustered. To obviate potential problems, we propose a new approach based on the self-organizing map (SOM) technique. This approach exploits underlying nonlinear relation of the steady-state geomorphic concave-convex nature of hillslopes (from hilltop to bottom of the valley) to spatially limited soil textural data. The topographic features are extracted from Shuttle Radar Topographic Mission elevation data; whereas soil textural (clay, silt, and sand) and hydraulic data were collected in 29 spatially random locations (50 to 75. cm depth). In contrast to traditional principal component analysis, the SOM identifies relations among relief features, such as, slope, horizontal curvature and vertical curvature. Stochastic cross-validation indicates that the SOM is unbiased and provides a way to measure the magnitude of prediction uncertainty for all variables. The SOM cross-component plots of the soil texture reveals higher clay proportions at concave areas with convergent hydrological flux and lower proportions for convex areas with divergent flux. The sand ratio has an opposite pattern with higher values near the ridge and lower values near the valley. Silt has a trend similar to sand, although less pronounced. The relation between soil texture and concave-convex hillslope features reveals that subsurface weathering and transport is an important process that changed from loss-to-gain at the rectilinear hillslope point. These results illustrate that the SOM can be used to capture and predict nonlinear hillslope relations among relief, soil texture, and hydraulic conductivity data. ?? 2011 Elsevier B.V.

  8. Spatially distributed encoding of covert attentional shifts in human thalamus

    DEFF Research Database (Denmark)

    Hulme, Oliver J; Whiteley, Louise Emma; Shipp, Stewart

    2010-01-01

    . Target position was cued after stimulus offset, requiring subjects to perform target detection from iconic visual memory. We found positionally specific responses at multiple thalamic sites, with individual voxels activating at more than one direction of attentional shift. Voxel clusters at anatomically......Spatial attention modulates signal processing within visual nuclei of the thalamus--but do other nuclei govern the locus of attention in top-down mode? We examined functional MRI (fMRI) data from three subjects performing a task requiring covert attention to 1 of 16 positions in a circular array...

  9. Comparison of Different Turbulence Models for Numerical Simulation of Pressure Distribution in V-Shaped Stepped Spillway

    Directory of Open Access Journals (Sweden)

    Zhaoliang Bai

    2017-01-01

    Full Text Available V-shaped stepped spillway is a new shaped stepped spillway, and the pressure distribution is quite different from that of the traditional stepped spillway. In this paper, five turbulence models were used to simulate the pressure distribution in the skimming flow regimes. Through comparing with the physical value, the realizable k-ε model had better precision in simulating the pressure distribution. Then, the flow pattern of V-shaped and traditional stepped spillways was given to illustrate the unique pressure distribution using realizable k-ε turbulence model.

  10. Spatial Determinants of Import Traffic Distribution At Port Harcourt (Nigeria

    Directory of Open Access Journals (Sweden)

    Soddy I. Inyang

    2013-07-01

    Full Text Available This paper highlights the result of a study carried out to examine the Geographic determinants of import traffic distribution at the Port Harcourt Port. A substantial aspect of the study involved building a regression model to estimate import distribution from the Port. The import function was specified in log-linear form. The adequacy of the model was then tested; this, involved statistical experiments to obtain the R-squared, as well as t and f values. Further test on the adequacy of the nwdel was conducted through diagnostic exercises designed to check for inulticollinedrity and heteroscedasticity, in the data used. Results obtained show that road distance and manufacturing industries are significant Geographic determinants of import Cargo distribution at the study Port. It is therefore important to lake the two variables into account in any policy or planning exercise at Port Harcourt Port.

  11. Geographic coupling of juvenile and adult habitat shapes spatial population dynamics of a coral reef fish

    NARCIS (Netherlands)

    Huijbers, C.M.; Nagelekerken, I.; Debrot, A.O.; Jongejans, E.

    2013-01-01

    Marine spatial population dynamics are often addressed with a focus on larval dispersal, without taking into account movement behavior of individuals in later life stages. Processes occurring during demersal life stages may also drive spatial population dynamics if habitat quality is perceived

  12. Impacts of Spatial Distribution of Impervious Areas on Runoff Response of Hillslope Catchments: Simulation Study

    Science.gov (United States)

    This study analyzes variations in the model-projected changes in catchment runoff response after urbanization that stem from variations in the spatial distribution of impervious areas, interevent differences in temporal rainfall structure, and antecedent soil moisture (ASM). In t...

  13. Identification of Msf tide amplification using a network of spatially distributed tide gauges

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A; Mehra, P.; Sivadas, T.K.; Desai, R.G.P.; Srinivas, K.; Thottam, T.; Vijayan, P.R.; Revichandran, C.; Balachandran, K.K.

    Attenuation of tidal range (approx. 73%) and amplification of fortnightly Msf tide (approx. 10-fold) in the southern region of Kochi backwaters has been identified based on measurements by a network of spatially distributed rotary transducer based...

  14. Modelling the distribution of fish accounting for spatial correlation and overdispersion

    DEFF Research Database (Denmark)

    Lewy, Peter; Kristensen, Kasper

    2009-01-01

    The spatial distribution of cod (Gadus morhua) in the North Sea and the Skagerrak was analysed over a 24-year period using the Log Gaussian Cox Process (LGCP). In contrast to other spatial models of the distribution of fish, LGCP avoids problems with zero observations and includes the spatial...... correlation between observations. It is therefore possible to predict and interpolate unobserved densities at any location in the area. This is important for obtaining unbiased estimates of stock concentration and other measures depending on the distribution in the entire area. Results show that the spatial...... correlation and dispersion of cod catches remained unchanged during winter throughout the period, in spite of a drastic decline in stock abundance and a movement of the centre of gravity of the distribution towards the northeast in the same period. For the age groups considered, the concentration of the stock...

  15. Predicting the geo-spatial distribution of Bulinus snail vector of ...

    African Journals Online (AJOL)

    Bulinus spp, are freshwater snails that serve as intermediate hosts of Schistosoma heamatobium which cause urinary schistosomiasis in human beings. The knowledge of their spatial distributions can be used to map the extent and risk of the disease in endemic areas. This paper therefore, presents the geo-spatial ...

  16. Spatial distribution and temporal trends of rainfall erosivity in mainland China for 1951-2010

    Science.gov (United States)

    Wei Qin; Qiankun Guo; Changqing Zuo; Zhijie Shan; Liang Ma; Ge Sun

    2016-01-01

    Rainfall erosivity is an important factor for estimating soil erosion rates. Understanding the spatial distributionand temporal trends of rainfall erosivity is especially critical for soil erosion risk assessment and soil conservationplanning in mainland China. However, reports on the spatial distribution and temporal trends of rainfall...

  17. Pattern and spatial distribution of plague in Lushoto, north-eastern ...

    African Journals Online (AJOL)

    A review of plague records from 1986 to 2002 and household interviews were carried out in the plague endemic villages to establish a pattern and spatial distribution of the disease in Lushoto district, Tanzania. Spatial data of households and village centres were collected and mapped using a hand held Global Positioning ...

  18. Spatial distribution of human-caused forest fires in Galicia (NW Spain)

    Science.gov (United States)

    M. L. Chas-Amil; J. Touza; P. Prestemon

    2010-01-01

    It is crucial for fire prevention policies to assess the spatial patterns of human-started fires and their relationship with geographical and socioeconomic aspects. This study uses fire reports for the period 1988-2006 in Galicia, Spain, to analyze the spatial distribution of human-induced fire risk attending to causes and underlying motivations associated with fire...

  19. Predicting the spatial distribution of leaf litterfall in a mixed deciduous forest

    NARCIS (Netherlands)

    Staelens, Jeroen; Nachtergale, Lieven; Luyssaert, Sebastiaan

    2004-01-01

    An accurate prediction of the spatial distribution of litterfall can improve insight in the interaction between the canopy layer and forest floor characteristics, which is a key feature in forest nutrient cycling. Attempts to model the spatial variability of litterfall have been made across forest

  20. Distribution of shape elongations of main belt asteroids derived from Pan-STARRS1 photometry

    Science.gov (United States)

    Cibulková, H.; Nortunen, H.; Ďurech, J.; Kaasalainen, M.; Vereš, P.; Jedicke, R.; Wainscoat, R. J.; Mommert, M.; Trilling, D. E.; Schunová-Lilly, E.; Magnier, E. A.; Waters, C.; Flewelling, H.

    2018-04-01

    Context. A considerable amount of photometric data is produced by surveys such as Pan-STARRS, LONEOS, WISE, or Catalina. These data are a rich source of information about the physical properties of asteroids. There are several possible approaches for using these data. Light curve inversion is a typical method that works with individual asteroids. Our approach in focusing on large groups of asteroids, such as dynamical families and taxonomic classes, is statistical; the data are not sufficient for individual models. Aim. Our aim is to study the distributions of shape elongation b/a and the spin axis latitude β for various subpopulations of asteroids and to compare our results, based on Pan-STARRS1 survey, with statistics previously carried out using various photometric databases, such as Lowell and WISE. Methods: We used the LEADER algorithm to compare the b/a and β distributions for various subpopulations of asteroids. The algorithm creates a cumulative distributive function (CDF) of observed brightness variations, and computes the b/a and β distributions with analytical basis functions that yield the observed CDF. A variant of LEADER is used to solve the joint distributions for synthetic populations to test the validity of the method. Results: When comparing distributions of shape elongation for groups of asteroids with different diameters D, we found that there are no differences for D < 25 km. We also constructed distributions for asteroids with different rotation periods and revealed that the fastest rotators with P = 0 - 4 h are more spheroidal than the population with P = 4-8 h.

  1. [Spatial distribution characteristics of NMHCs during winter haze in Beijing].

    Science.gov (United States)

    Duan, Jing-Chun; Peng, Yan-Chun; Tan, Ji-Hua; Hao, Ji-Ming; Chai, Fa-He

    2013-12-01

    NMHCs and NOx samples were simultaneously collected and analyzed in six urban and suburban representative sampling sites (Sihuan, Tian'anmen, Pinguoyuan, Fatou, Beijing Airport and Miyun) during a typical haze period in winter 2005, Beijing. The concentrations of NMHCs during the sampling period in descending order were: Sihuan (1101.29 microg x m(-3)) > Fatou (692.40 microg x m(-3)) >Tian'anmen (653.28 microg x m(-3)) >Pinguoyuan (370.27 microg x m(-3)) > Beijing Airport (350.36 microg x m(-3)) > Miyun (199.97 microg x m(-3)). Atmospheric benzene pollution in Beijing was rather serious. The ratio of NMHCs/NOx ranged from 2.1 to 6.3, indicating that the peak ozone concentrations in urban Beijing were controlled by VOCs during the sampling period. Analysis of propylene equivalent concentration and ozone formation potential showed that the NMHCs reactivity descended in the order of Sihuan > Fatou > Tian'anmen > Pinguoyuan > Beijing Airport > Miyun. B/T values (0.52 to 0.76) indicated that besides motor vehicle emission, coal combustion and other emission sources were also the sources of NHMCs in Beijing in winter. The spatial variations of isoprene in Beijing indicated that the contribution of anthropogenic sources to isoprene increased and the emissions by biogenic sources decreased in winter. The spatial variations of propane and butane indicated that LPG emissions existed in the urban region of Beijing.

  2. Spatially distributed encoding of covert attentional shifts in human thalamus.

    Science.gov (United States)

    Hulme, Oliver J; Whiteley, Louise; Shipp, Stewart

    2010-12-01

    Spatial attention modulates signal processing within visual nuclei of the thalamus--but do other nuclei govern the locus of attention in top-down mode? We examined functional MRI (fMRI) data from three subjects performing a task requiring covert attention to 1 of 16 positions in a circular array. Target position was cued after stimulus offset, requiring subjects to perform target detection from iconic visual memory. We found positionally specific responses at multiple thalamic sites, with individual voxels activating at more than one direction of attentional shift. Voxel clusters at anatomically equivalent sites across subjects revealed a broad range of directional tuning at each site, with little sign of contralateral bias. By reference to a thalamic atlas, we identified the nuclear correspondence of the four most reliably activated sites across subjects: mediodorsal/central-intralaminar (oculomotor thalamus), caudal intralaminar/parafascicular, suprageniculate/limitans, and medial pulvinar/lateral posterior. Hence, the cortical network generating a top-down control signal for relocating attention acts in concert with a spatially selective thalamic apparatus-the set of active nuclei mirroring the thalamic territory of cortical "eye-field" areas, thus supporting theories which propose the visuomotor origins of covert attentional selection.

  3. Spatial pattern of 2009 dengue distribution in Kuala Lumpur using GIS application.

    Science.gov (United States)

    Aziz, S; Ngui, R; Lim, Y A L; Sholehah, I; Nur Farhana, J; Azizan, A S; Wan Yusoff, W S

    2012-03-01

    In the last few years in Malaysia, dengue fever has increased dramatically and has caused huge public health concerns. The present study aimed to establish a spatial distribution of dengue cases in the city of Kuala Lumpur using a combination of Geographic Information System (GIS) and spatial statistical tools. Collation of data from 1,618 dengue cases in 2009 was obtained from Kuala Lumpur City Hall (DBKL). These data were processed and then converted into GIS format. Information on the average monthly rainfall was also used to correlate with the distribution pattern of dengue cases. To asses the spatial distribution of dengue cases, Average Nearest Neighbor (ANN) Analysis was applied together with spatial analysis with the ESRI ArcGIS V9.3 programme. Results indicated that the distribution of dengue cases in Kuala Lumpur for the year 2009 was spatially clustered with R value less than 1 (R = 0.42; z-scores = - 4.47; p 1) between August and November. In addition, the mean monthly rainfall has not influenced the distribution pattern of the dengue cases. Implementation of control measures is more difficult for dispersed pattern compared to clustered pattern. From this study, it was found that distribution pattern of dengue cases in Kuala Lumpur in 2009 was spatially distributed (dispersed or clustered) rather than cases occurring randomly. It was proven that by using GIS and spatial statistic tools, we can determine the spatial distribution between dengue and population. Utilization of GIS tools is vital in assisting health agencies, epidemiologist, public health officer, town planner and relevant authorities in developing efficient control measures and contingency programmes to effectively combat dengue fever.

  4. The Global Experience of Development of the Theory of Spatial Distribution of Productive Forces

    OpenAIRE

    Heiman Oleh A.; Kosyrieva Olena V.; Krasnonosova Yelena N.

    2016-01-01

    The publication is aimed at theoretical generalization of the global experience of development of the theory of spatial distribution of productive forces as the basis of regional economy. Considering the evolution of scientific views on the spatial development of territories, taking account of the particularities of the distribution of production, one can allocate and identify several paradigms, which replaced each other, but preserved their connection with the placement of ...

  5. Distributed Spatial Interference Coordination for IEEE 802.11n Wireless Networks

    Science.gov (United States)

    Chen, Rui; Li, Changle; Li, Jiandong

    The 802.11n networks with MIMO technique provide a spatial degree of freedom for dealing with co-channel interference. In this letter, our proposed spatial interference coordination scheme is achieved by distributed precoding for the downlink and distributed multi-user detection for the uplink. Simulation results validate the proposed scheme in terms of the downlink and uplink maximum achievable rates at each AP.

  6. Effect of Action Video Games on the Spatial Distribution of Visuospatial Attention

    OpenAIRE

    Green, C. Shawn; Bavelier, Daphne

    2006-01-01

    The authors investigated the effect of action gaming on the spatial distribution of attention. The authors used the flanker compatibility effect to separately assess center and peripheral attentional resources in gamers versus nongamers. Gamers exhibited an enhancement in attentional resources compared with nongamers, not only in the periphery but also in central vision. The authors then used a target localization task to unambiguously establish that gaming enhances the spatial distribution o...

  7. Spatial Distribution of Energy Consumption and Carbon Emission of Regional Logistics

    OpenAIRE

    Xiao, Fan; Hu, Zhi-Hua; Wang, Ke-Xin; Fu, Pei-Hua

    2015-01-01

    Facing serious energy-related constraints and environmental stress, the development of the green logistics industry is restricted by degrees of logistics energy utilization and carbon emissions. Considering different logistics spatial distributions, this paper uses the degree of regional logistics energy utilization and the spatial distribution of carbon emissions as two indicators of green logistics to investigate the regional differences and changes in spatiotemporal logistics energy effici...

  8. First insights on spatial and temporal distribution patterns of ...

    African Journals Online (AJOL)

    Our findings will be useful for the development of strategic sustained management plans by providing baseline information on humpback whale distribution at an important but poorly documented breeding site. Keywords: habitat use, Indian Ocean, Megaptera novaeangliae, phenology, seasonality pattern, social groups ...

  9. Non-homogeneous Behaviour of the Spatial Distribution of ...

    Indian Academy of Sciences (India)

    positions of the activity and its time variation have been calculated. The migration of the longitudinal distribution of macrospicules shows a similar behaviour to that of the sunspot groups. Key words. Active longitude—macrospicules. 1. Introduction. The behaviour of solar non-axisymmetric activity has been studied since the ...

  10. Control of the spatial distribution and crystal orientation of self-organized Au nanoparticles.

    Science.gov (United States)

    Yasukawa, Yukiko; Liu, Xiaoxi; Shirsath, Sagar E; Suematsu, Hisayuki; Kotaki, Yukio; Nemoto, Yoshihiro; Takeguchi, Masaki; Morisako, Akimitsu

    2016-09-23

    Ordered, two-dimensional, self-organized Au nanoparticles were fabricated using radiofrequency (RF) magnetron sputtering. The particles were uniformly spherical in shape and ultrafine in size (3-7 nm) and showed an ultrahigh density in the order of ∼10(12) inch(-2). A custom-developed sputtering apparatus that employs low sputtering power density and a minimized sputtering time (1 min) was used to markedly simplify the preparation conditions for Au nanoparticle fabrication. The spatial distribution of Au nanoparticles was rigorously controlled by placing a Ta interfacial layer between the Au nanoparticles and substrate as well as by post-annealing samples in an Ar atmosphere after the formation of Au nanoparticles. The interfacial layer and the post-annealing step caused approximately 40% of the Au nanoparticles on the substrate surface to orient in the (111) direction. This method was shown to produce ultrafine Au nanoparticles showing an ultrahigh surface density. The crystal orientation of the nanoparticles can be precisely controlled with respect to the substrate surface. Therefore, this technique promises to deliver tunable nanostructures for applications in the field of high-performance electronic devices.

  11. Shell Shape Analysis and Spatial Allometry Patterns of Manila Clam (Ruditapes philippinarum in a Mesotidal Coastal Lagoon

    Directory of Open Access Journals (Sweden)

    Nathalie Caill-Milly

    2012-01-01

    Full Text Available While gradual allometric changes of shells are intrinsically driven by genotype, morphometrical shifts can also be modulated by local environmental conditions. Consequently the common use of a unique dimension (usually length to assess bivalves’ growth may mask phenotypic differences in valve shape among populations. A morphometric exhaustive study was conducted on Manila clam, Ruditapes philippinarum, by acquiring data in the French Arcachon Bay (intrasite phenotypic variability and by comparing with other sites in the literature (intersite phenotypic variability. 2070 shells were subsampled, weighted, and automatically measured using TNPC software. Some ratios’ values indicate a relatively round and globular shape shell in comparison with other sites confirming poor conditions for some individuals. Among adult clams, three main morphological groups were identified and discussed according to spatial considerations. Allometric relations for pairs of shell descriptors were determined by testing classical linear and piecewise regression models on log-transformed relation of Huxley. A significant shape change correlated to size was observed; it corresponds to the second year of life of the clam. Relationships between density, disease, and shell shape are demonstrated and discussed related to other potential factors affecting shell shape. Finally, consequences on population regulation are addressed.

  12. A method for statistically comparing spatial distribution maps

    Directory of Open Access Journals (Sweden)

    Reynolds Mary G

    2009-01-01

    Full Text Available Abstract Background Ecological niche modeling is a method for estimation of species distributions based on certain ecological parameters. Thus far, empirical determination of significant differences between independently generated distribution maps for a single species (maps which are created through equivalent processes, but with different ecological input parameters, has been challenging. Results We describe a method for comparing model outcomes, which allows a statistical evaluation of whether the strength of prediction and breadth of predicted areas is measurably different between projected distributions. To create ecological niche models for statistical comparison, we utilized GARP (Genetic Algorithm for Rule-Set Production software to generate ecological niche models of human monkeypox in Africa. We created several models, keeping constant the case location input records for each model but varying the ecological input data. In order to assess the relative importance of each ecological parameter included in the development of the individual predicted distributions, we performed pixel-to-pixel comparisons between model outcomes and calculated the mean difference in pixel scores. We used a two sample Student's t-test, (assuming as null hypothesis that both maps were identical to each other regardless of which input parameters were used to examine whether the mean difference in corresponding pixel scores from one map to another was greater than would be expected by chance alone. We also utilized weighted kappa statistics, frequency distributions, and percent difference to look at the disparities in pixel scores. Multiple independent statistical tests indicated precipitation as the single most important independent ecological parameter in the niche model for human monkeypox disease. Conclusion In addition to improving our understanding of the natural factors influencing the distribution of human monkeypox disease, such pixel-to-pixel comparison

  13. Optimal exploitation of spatially distributed trophic resources and population stability

    Science.gov (United States)

    Basset, A.; Fedele, M.; DeAngelis, D.L.

    2002-01-01

    The relationships between optimal foraging of individuals and population stability are addressed by testing, with a spatially explicit model, the effect of patch departure behaviour on individual energetics and population stability. A factorial experimental design was used to analyse the relevance of the behavioural factor in relation to three factors that are known to affect individual energetics; i.e. resource growth rate (RGR), assimilation efficiency (AE), and body size of individuals. The factorial combination of these factors produced 432 cases, and 1000 replicate simulations were run for each case. Net energy intake rates of the modelled consumers increased with increasing RGR, consumer AE, and consumer body size, as expected. Moreover, through their patch departure behaviour, by selecting the resource level at which they departed from the patch, individuals managed to substantially increase their net energy intake rates. Population stability was also affected by the behavioural factors and by the other factors, but with highly non-linear responses. Whenever resources were limiting for the consumers because of low RGR, large individual body size or low AE, population density at the equilibrium was directly related to the patch departure behaviour; on the other hand, optimal patch departure behaviour, which maximised the net energy intake at the individual level, had a negative influence on population stability whenever resource availability was high for the consumers. The consumer growth rate (r) and numerical dynamics, as well as the spatial and temporal fluctuations of resource density, which were the proximate causes of population stability or instability, were affected by the behavioural factor as strongly or even more strongly than by the others factors considered here. Therefore, patch departure behaviour can act as a feedback control of individual energetics, allowing consumers to optimise a potential trade-off between short-term individual fitness

  14. Spatial factor analysis: a new tool for estimating joint species distributions and correlations in species range

    DEFF Research Database (Denmark)

    Thorson, James T.; Scheuerell, Mark D.; Shelton, Andrew O.

    2015-01-01

    1. Predicting and explaining the distribution and density of species is one of the oldest concerns in ecology. Species distributions can be estimated using geostatistical methods, which estimate a latent spatial variable explaining observed variation in densities, but geostatistical methods may...... be imprecise for species with low densities or few observations. Additionally, simple geostatistical methods fail to account for correlations in distribution among species and generally estimate such cross-correlations as a post hoc exercise. 2. We therefore present spatial factor analysis (SFA), a spatial...... model for estimating a low-rank approximation to multivariate data, and use it to jointly estimate the distribution of multiple species simultaneously. We also derive an analytic estimate of cross-correlations among species from SFA parameters. 3. As a first example, we show that distributions for 10...

  15. Cartograms tool to represent spatial uncertainty in species distribution

    Directory of Open Access Journals (Sweden)

    Duccio Rocchini

    2017-02-01

    Full Text Available Species distribution models have become an important tool for biodiversity monitoring. Like all statistical modelling techniques developed based on field data, they are prone to uncertainty due to bias in the sampling (e.g. identification, effort, detectability. In this study, we explicitly quantify and map the uncertainty derived from sampling effort bias. With that aim, we extracted data from the widely used GBIF dataset to map this semantic bias using cartograms.

  16. Solid-phase laser-induced forward transfer of variable shapes using a liquid-crystal spatial light modulator

    Science.gov (United States)

    Pohl, R.; Jansink, M.; Römer, G. R. B. E.; Huis in `t Veld, A. J.

    2015-08-01

    Laser-induced forward transfer is a promising method for 3D printing of various materials, including metals. The ejection mechanism is complex and depends strongly on the experimental parameters, such as laser fluence and donor layer thickness. However, the process can be categorized by the physical condition of the ejected material, i.e., the donor layer is transferred in liquid phase or the material is transferred as a `pellet' in solid phase. Currently, solid-phase transfer faces several problems. Large shearing forces, occurring at the pellet perimeter during transfer, limit the similarity between the desired pellet shape and the deposited pellet shape. Furthermore, the deposited pellet may be surrounded by debris particles formed by undesired transferred donor material. This work introduces a novel approach for laser-induced forward transfer of variable shaped solid-phase pellets. A liquid-crystal spatial light modulator (SLM) is used to apply grayscale intensity modulation to an incident laser beam to shape the intensity profile. Optimized beams consist of a high fluence perimeter around an interior characterized by a lower fluence level. These beams are used successfully to transfer solid-phase pellets out of a 100-nm Au donor layer using a single laser pulse. The flexibility of the SLM allows a variable desired pellet shape. The shapes of the resulting deposited pellets show a high degree of similarity to the desired shapes. Debris-free deposited pellets are achieved by pre-machining the donor layer, prior to the transfer, using a double-pulse process.

  17. Simulation of spatial distribution of absorbed laser energy in spherical microcapsules

    Science.gov (United States)

    Geints, Yu E.; Zemlyanov, A. A.; Panina, E. K.

    2016-09-01

    Specific features of optical field distribution in composite spherical particles consisting of a liquid core and nanocomposite absorbing shell are theoretically studied at different wavelengths of incident radiation. Using the numerical simulation it is shown that the thickness of the shell of the spherical microcapsule particle and its intrinsic absorption coefficient determine the character of the spatial distribution and the absorbed power. The variation of these parameters allows one to change the spatial position of efficient volume absorption regions and peak absorption values. This provides favourable conditions for opening the shells in appropriate spatial zones to release the contents of the microcapsules.

  18. The study for the Spatial Distribution Pattern of NDVI in the Western of Jilin Province

    Science.gov (United States)

    Yang, Shu-jie; Li, Xiao-dong; Yan, Shou-gang

    2018-02-01

    Using methods of spatial autocorrelation analysis and trend analysis, the paper studies the spatial distribution pattern of NDVI based on the GIMMS NDVI dataset (1998-2008), in Western Jilin. The maximum value for 15d is got through the method of MAX processing. Results show that: the NDVI in growing season shows a rising trend in western Jilin in 1998-2008. In the study area, the NDVI in Western Jilin shows positive spatial autocorrelation in the whole region, but the partial NDVI is apt to scattered distribution, which means the vegetation cover of Western Jilin is generally fragmental.

  19. Shaping and detecting mid-IR light with a spatial light modulator

    CSIR Research Space (South Africa)

    Maweza, Elijah L

    2016-10-01

    Full Text Available We demonstrate the operation and calibration of a spatial light modulator in the mid-IR region by creating and measuring the modal content and wavefront of structured light fields at 2um for the first time....

  20. Spatial and temporal distribution of trunk-injected imidacloprid in apple tree canopies.

    Science.gov (United States)

    Aćimović, Srđan G; VanWoerkom, Anthony H; Reeb, Pablo D; Vandervoort, Christine; Garavaglia, Thomas; Cregg, Bert M; Wise, John C

    2014-11-01

    Pesticide use in orchards creates drift-driven pesticide losses which contaminate the environment. Trunk injection of pesticides as a target-precise delivery system could greatly reduce pesticide losses. However, pesticide efficiency after trunk injection is associated with the underinvestigated spatial and temporal distribution of the pesticide within the tree crown. This study quantified the spatial and temporal distribution of trunk-injected imidacloprid within apple crowns after trunk injection using one, two, four or eight injection ports per tree. The spatial uniformity of imidacloprid distribution in apple crowns significantly increased with more injection ports. Four ports allowed uniform spatial distribution of imidacloprid in the crown. Uniform and non-uniform spatial distributions were established early and lasted throughout the experiment. The temporal distribution of imidacloprid was significantly non-uniform. Upper and lower crown positions did not significantly differ in compound concentration. Crown concentration patterns indicated that imidacloprid transport in the trunk occurred through radial diffusion and vertical uptake with a spiral pattern. By showing where and when a trunk-injected compound is distributed in the apple tree canopy, this study addresses a key knowledge gap in terms of explaining the efficiency of the compound in the crown. These findings allow the improvement of target-precise pesticide delivery for more sustainable tree-based agriculture. © 2014 Society of Chemical Industry.

  1. Cooperation in carbon source degradation shapes spatial self-organization of microbial consortia on hydrated surfaces

    OpenAIRE

    Tecon, Robin; Or, Dani

    2017-01-01

    Mounting evidence suggests that natural microbial communities exhibit a high level of spatial organization at the micrometric scale that facilitate ecological interactions and support biogeochemical cycles. Microbial patterns are difficult to study definitively in natural environments due to complex biodiversity, observability and variable physicochemical factors. Here, we examine how trophic dependencies give rise to self-organized spatial patterns of a well-defined bacterial consortium grow...

  2. Continuous time modelling of dynamical spatial lattice data observed at sparsely distributed times

    DEFF Research Database (Denmark)

    Rasmussen, Jakob Gulddahl; Møller, Jesper

    2007-01-01

    , and they exhibit spatial interaction. For specificity we consider a particular dynamical spatial lattice data set which has previously been analysed by a discrete time model involving unknown normalizing constants. We discuss the advantages and disadvantages of using continuous time processes compared......Summary. We consider statistical and computational aspects of simulation-based Bayesian inference for a spatial-temporal model based on a multivariate point process which is only observed at sparsely distributed times. The point processes are indexed by the sites of a spatial lattice...

  3. A New Catalogue of Galactic Novae: Investigation of the MMRD relation & Spatial Distribution

    Science.gov (United States)

    Özdönmez, Aykut; Ege, Ergün; Güver, Tolga; Ak, Tansel

    2018-02-01

    In this study, a new Galactic novae catalogue is introduced collecting important parameters of these sources such as their light curve parameters, classifications, full width half maximum (FWHM) of Hα line, distances and interstellar reddening estimates. The catalogue is also published on a website with a search option via a SQL query and an online tool to re-calculate the distance/reddening of a nova from the derived reddening-distance relations. Using the novae in the catalogue, the existence of a maximum magnitude-rate of decline (MMRD) relation in the Galaxy is investigated. Although an MMRD relation was obtained, a significant scattering in the resulting MMRD distribution still exists. We suggest that the MMRD relation likely depends on other parameters in addition to the decline time, as FWHM Hα, the light curve shapes. Using two different samples depending on the distances in the catalogue and from the derived MMRD relation, the spatial distributions of Galactic novae as a function of their spectral and speed classes were studied. The investigation on the Galactic model parameters implies that best estimates for the local outburst density are 3.6 and 4.2 × 10-10 pc-3 yr-1 with a scale height of 148 and 175 pc, while the space density changes in the range of 0.4 - 16 × 10-6 pc-3. The local outburst density and scale height obtained in this study infer that the disk nova rate in the Galaxy is in the range of ˜20 to ˜100 yr-1 with an average estimate 67^{+21}_{-17} yr-1.

  4. Analysis of the Spatial Distribution of Galaxies by Multiscale Methods

    Directory of Open Access Journals (Sweden)

    E. Saar

    2005-09-01

    Full Text Available Galaxies are arranged in interconnected walls and filaments forming a cosmic web encompassing huge, nearly empty, regions between the structures. Many statistical methods have been proposed in the past in order to describe the galaxy distribution and discriminate the different cosmological models. We present in this paper multiscale geometric transforms sensitive to clusters, sheets, and walls: the 3D isotropic undecimated wavelet transform, the 3D ridgelet transform, and the 3D beamlet transform. We show that statistical properties of transform coefficients measure in a coherent and statistically reliable way, the degree of clustering, filamentarity, sheetedness, and voidedness of a data set.

  5. Spatial distribution of sodium vapor in the atmosphere of Mercury

    International Nuclear Information System (INIS)

    Killen, R.M.; Potter, A.E.; Morgan, T.H.

    1990-01-01

    The present study indicates that the Na content of the Mercury exosphere is influenced by both diurnally and sporadically varying forces; radiation pressure is identified with the former, and solar wind-magnetosphere interactions with the latter. The latitudinal distribution is highly variable on a timescale of less than one day, and significant enhancements are found in Na abundance at one pole. It is suggested that a significant amount of Na recycling through an exosphere-magnetosphere coupling may be responsible for this effect. The magnetosphere provides a mechanism for transport of Na toward the poles, and for subsequent loss in the polar loss cones. 45 refs

  6. Spatial distribution of China׳s renewable energy industry

    DEFF Research Database (Denmark)

    Dong, Liang; Liang, Hanwei; Gao, Zhiqiu

    2016-01-01

    China applies no efforts to promote the development of renewable energy (REE) so as to enhance China׳s energy security and address climate change. National top-down support scheme and the local renewable energy industry (REEI) development are the two important and intervened countermeasures......, included Bohai sea region, Yangtze River Delta, middle area, and western area. Supply chains were diversely distributed based on the regional resources allocation as well as economy development level and. In summary, REE resource supply and transformation facilities construction were the main REEI...

  7. THE NATURE OF STARBURSTS. III. THE SPATIAL DISTRIBUTION OF STAR FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W.; Skillman, Evan D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Holtzman, Jon, E-mail: kmcquinn@astro.umn.edu [Department of Astronomy, New Mexico State University, Box 30001-Department 4500, 1320 Frenger Street, Las Cruces, NM 88003 (United States)

    2012-11-01

    We map the spatial distribution of recent star formation over a few Multiplication-Sign 100 Myr timescales in 15 starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., H{alpha} emission), there could be a strong bias toward classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially distributed.

  8. Big Pylons: Mixed signals for transmission. Spatial planning for energy distribution

    International Nuclear Information System (INIS)

    Ritchie, Heather; Hardy, Maelíosa; Lloyd, M. Greg; McGreal, Stanley

    2013-01-01

    The effective delivery of a sustainable energy future raises many challenges in relation to energy distribution where a new understanding of spatial planning is needed in relation to energy production, consumption and storage. Understanding the emergent low carbon energy economy in terms of its production, distribution and consumption characteristics has prompted a deliberate spatial planning interest. This paper examines issues relating to spatial planning, regulation, political legitimacy and accountability in the current and future systems for energy distribution. In particular it examines the Beauly Denny public inquiry in Scotland as a case study in terms of demonstrating the changing state–market–civil relations in an energy transition context with differentiated values and interests. The case study highlights implications for the regulation in the public interest of highly contested spaces, places and development schemes, together with a synopsis of government structure and change that is influencing the future of spatial planning and energy distribution in particular. - Highlights: • We examine links between spatial planning and regulation of energy distribution. • We examine the Beauly Denny public inquiry in Scotland. • We highlight challenges surrounding the development of a resilient energy system. • We highlight links between spatial planning and infrastructural development

  9. Spatial Mapping and Profiling of Metabolite Distributions during Germination.

    Science.gov (United States)

    Feenstra, Adam D; Alexander, Liza E; Song, Zhihong; Korte, Andrew R; Yandeau-Nelson, Marna D; Nikolau, Basil J; Lee, Young Jin

    2017-08-01

    Germination is a highly complex process by which seeds begin to develop and establish themselves as viable organisms. In this study, we utilize a combination of gas chromatography-mass spectrometry, liquid chromatography-fluorescence, and mass spectrometry imaging approaches to profile and visualize the metabolic distributions of germinating seeds from two different inbreds of maize ( Zea mays ) seeds, B73 and Mo17. Gas chromatography and liquid chromatography analyses demonstrate that the two inbreds are highly differentiated in their metabolite profiles throughout the course of germination, especially with regard to amino acids, sugar alcohols, and small organic acids. Crude dissection of the seed followed by gas chromatography-mass spectrometry analysis of polar metabolites also revealed that many compounds were highly sequestered among the various seed tissue types. To further localize compounds, matrix-assisted laser desorption/ionization mass spectrometry imaging was utilized to visualize compounds in fine detail in their native environments over the course of germination. Most notably, the fatty acyl chain-dependent differential localization of phospholipids and triacylglycerols was observed within the embryo and radicle, showing correlation with the heterogeneous distribution of fatty acids. Other interesting observations include unusual localization of ceramides on the endosperm/scutellum boundary and subcellular localization of ferulate in the aleurone. © 2017 American Society of Plant Biologists. All Rights Reserved.

  10. Building better water models using the shape of the charge distribution of a water molecule

    Science.gov (United States)

    Dharmawardhana, Chamila Chathuranga; Ichiye, Toshiko

    2017-11-01

    The unique properties of liquid water apparently arise from more than just the tetrahedral bond angle between the nuclei of a water molecule since simple three-site models of water are poor at mimicking these properties in computer simulations. Four- and five-site models add partial charges on dummy sites and are better at modeling these properties, which suggests that the shape of charge distribution is important. Since a multipole expansion of the electrostatic potential describes a charge distribution in an orthogonal basis set that is exact in the limit of infinite order, multipoles may be an even better way to model the charge distribution. In particular, molecular multipoles up to the octupole centered on the oxygen appear to describe the electrostatic potential from electronic structure calculations better than four- and five-site models, and molecular multipole models give better agreement with the temperature and pressure dependence of many liquid state properties of water while retaining the computational efficiency of three-site models. Here, the influence of the shape of the molecular charge distribution on liquid state properties is examined by correlating multipoles of non-polarizable water models with their liquid state properties in computer simulations. This will aid in the development of accurate water models for classical simulations as well as in determining the accuracy needed in quantum mechanical/molecular mechanical studies and ab initio molecular dynamics simulations of water. More fundamentally, this will lead to a greater understanding of how the charge distribution of a water molecule leads to the unique properties of liquid water. In particular, these studies indicate that p-orbital charge out of the molecular plane is important.

  11. Optimum Aggregation and Control of Spatially Distributed Flexible Resources in Smart Grid

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Mendaza, Iker Diaz de Cerio; Myers, Kurt S.

    2018-01-01

    This study presents an algorithm to optimally aggregate spatially distributed flexible resources at strategic microgrid/smart-grid locations. The aggregation reduces a distribution network having thousands of nodes to an equivalent network with a few aggregated nodes, thereby enabling distributio...

  12. Characterizing the spatial distribution of giant pandas (Ailuropoda melanoleuca) in fragmented forest landscapes

    NARCIS (Netherlands)

    Wang, T.; Ye, X.P.; Skidmore, A.K.; Toxopeus, A.G.

    2010-01-01

    Aim. To examine the effects of forest fragmentation on the distribution of the entire wild giant panda (Ailuropoda melanoleuca) population, and to propose a modelling approach for monitoring the spatial distribution and habitat of pandas at the landscape scale using Moderate Resolution Imaging

  13. Attention, spatial integration, and the tail of response time distributions in Stroop task performance

    NARCIS (Netherlands)

    Roelofs, A.P.A.

    2012-01-01

    A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as

  14. Temporal and spatial patterns in the distribution of squid Loligo spp ...

    African Journals Online (AJOL)

    A Geographic Information System (GIS) was used to test hypotheses regarding the spatial distribution of the squid Loligo forbesi and Loligo vulgaris vulgaris in the northern North-East Atlantic during the years 1989-1994. Loligo spp. were present throughout coastal waters of the United Kingdom, but distribution was patchy ...

  15. Minimizing the energy spread within a single bunch by shaping its charge distribution

    International Nuclear Information System (INIS)

    Loew, G.A.; Wang, J.W.

    1985-03-01

    It has been known for some time that partial compensation of the longitudinal wake field effects can be obtained for any bunch by placing it ahead of the accelerating crest (in space), thereby letting the positive rising sinusoidal field offset the negative beam loading field. The work presented in this paper shows that it is possible to obtain complete compensation, i.e., to reduce the energy spread essentially to zero by properly shaping the longitudinal charge distribution of the bunch and by placing it at the correct position on the wave. 3 refs., 5 figs., 3 tabs

  16. Spatial distribution of juvenile and adult stages of limnetic Cladocera in relation to selected environmental factors

    Directory of Open Access Journals (Sweden)

    Małgorzata Adamczuk

    2012-01-01

    Full Text Available Environmental factors have a varied impact on the development of juvenile and adult Cladocera, depending on their different physiological conditions and body size. The values of these factors alter spatially and temporarily, thus implying that they play a role in the spatial distribution of the pre-reproductive and potentially reproductive stages of cladocerans. The aim of the study was to determine seasonal and spatial variations in the distribution of juvenile and adult individuals of limnetic Cladocera in relation to selected physicochemical factors (temperature, conductivity, pH, concentration of dissolved oxygen, total organic carbon, total suspended solids and fish predation pressure (measured by Chesson’s coefficient λ in deep Lake Piaseczno (eastern Poland. Adult Cladocera displayed spatial distribution related to fish predation pressure. The species selectively eaten, B. coregoni and D. longispina, and non-selectively eaten, D. cucullata, selected the pelagic zone to exist, whereas those avoided by fish, D. brachyurum and B. longirostris, were evenly distributed in the littoral and pelagic zone. Juvenile cladocerans were strongly impacted by physico-chemical factors. Juvenile Daphnia, Diaphanosoma and B. longirostris showed preferences to biotic zones similar to the adults but differed in their habitat choices. Juvenile and adult stages of B. coregoni differed in their distribution, indicating that adult individuals impacted by high predation pressure alternatively modified their habitat selection. Principal component analysis (PCA ordination showed a seasonal tendency for the spatial segregation of the cladocerans, suggesting that possible competitive interactions between the studied cladocerans may also influence their distribution patterns.

  17. Nitrogen Transformation and Microbial Spatial Distribution in Drinking Water Biofilter

    Science.gov (United States)

    Qian, Yongxing; Zhang, Huining; Jin, Huizheng; Wu, Chengxia

    2018-02-01

    Well understanding the rule of nitrogen mutual transformation in biofilters is important for controlling the DBPs formation in the subsequent disinfection process. Ammonia nitrogen removal effect and nitrogen transformation approach in biofilter of drinking water was researched in the study. The biofilter removed ammonia of 48.5% and total phosphorus of 72.3%. And the removal rate of TN, NO3 --N, DON were 37.1%, 33.1%, 46.9%, respectively. Biomass and bioactivity of different depth of the biofilter were determined, too. The overall distribution of biomass showed a decreasing trend from top to bottom. The bioactivity in lower layer gradually increased. Especially the bioactivity of heterotrophic microorganisms showed a gradual increase trend. The amount of the nitrogen loss was 3.06mg/L. Non-nitrification pathway of “nitrogen loss” phenomenon in biofilter might exist assimilation, nitrification and denitrification in autotrophic.

  18. GEMAS: Molybdenum Spatial Distribution Patterns in European Soil

    Science.gov (United States)

    Cicchella, Domenico; Zuzolo, Daniela; Demetriades, Alecos; De Vivo, Benedetto; Eklund, Mikael; Ladenberger, Anna; Negrel, Philippe; O'Connor, Patrick

    2017-04-01

    Molybdenum is an essential trace element for both plants and animals as well as for human being. It is one such trace element for which potential health concerns have been raised but for which few data exist and little investigation or interpretation of distributions in soils has been made. The main goal of this study was to fill this gap. Molybdenum (Mo) concentrations are reported for the Greece associated with sulfides mineralizations and in Slovenia and Croatia where are probably related to the long weathering history of karstic residual soils. Anomalous concentrations in some areas of Ireland represent a clear example of how an excess of molybdenum has produced potentially toxic pastures. In fact, these give rise to problems particularly in young cattle when excess molybdenum in the herbage acts as an antagonist, which militates against efficient copper absorption by the animal.

  19. On the spatial distribution of the M spectral type stars

    International Nuclear Information System (INIS)

    Kevanishvili, G.T.

    1982-01-01

    The distribution of M stars with known radial velocities is studied on the base of the Wilson catalogue data. M stars have turned out to show a trend to clustering. The analysis of distances between these grouping stars as well as of their radial velocities, proper motions and other physical characteristics has allowed to keep 24 such groupings. Data concerning the grouping configurations and different physical characteristics of group stars are given. The stars belonging to one group are mostly giants. As a rule each grouping has one or two emission stars, but sometimes all the stars of a grouping are emission ones. It is possible that these groupings are the physical ones and the stars contained in them are of a common origin

  20. Spatial distribution of absorbed dose onboard of International Space Station

    International Nuclear Information System (INIS)

    Jadrnickova, I.; Spumy, F.; Tateyama, R.; Yasuda, N.; Kawashima, H.; Kurano, M.; Uchihori, Y.; Kitamura, H.; Akatov, Yu.; Shurshakov, V.; Kobayashi, I.; Ohguchi, H.; Koguchi, Y.

    2009-01-01

    The passive detectors (LD and PNTD) were exposed onboard of Russian Service Module Qn the International Space Station (ISS) from August 2004 to October 2005 (425 days). The detectors were located at 6 different positions inside the Service Module and also in 32 pockets on the surface of the spherical tissue-equivalent phantom located in crew cabin. Distribution of absorbed doses and dose equivalents measured with passive detectors, as well as LET spectra of fluences of registered particles, are presented as the function of detectors' location. The variation of dose characteristics for different locations can be up to factor of 2. In some cases, data measured with passive detectors are also compared with the data obtained by means of active instruments. (authors)

  1. Spatial distribution of osteoblast activating peptide in the rat stomach.

    Science.gov (United States)

    Noreldin, Ahmed E; Sogabe, Maina; Yamano, Yoshiaki; Uehara, Masato; Mahdy, Mohamed A A; Elnasharty, Mohamed A; Sayed-Ahmed, Ahmed; Warita, Katsuhiko; Hosaka, Yoshinao Z

    2016-03-01

    Osteoblast activating peptide (OBAP) was previously reported to be expressed in the rat stomach and to have a vital role in osteogenesis, but its distribution in rat stomach has not been determined. Thus, the aim of the present study was to identify the cell types expressing OBAP in the rat stomach. The stomachs of twelve 10-to-11-week-old male Jc1:SD rats were used. Samples were collected for immunohistochemistry, immunoelectron microscopy and dot blot assay. Immunohistochemical investigation revealed that OBAP was distributed mainly in parietal cells without any expression in chief cells, X/A-like cells or enterochromaffin-like cells. Moreover, OBAP-immunopositive cells were observed mainly in the upper and lower parts of the gastric gland. Significantly high optical density of immunopositive cells was observed in the upper and lower gastric gland regions. The dot blot assay confirmed that OBAP is secreted by parietal cells and that it is present in the gastric gland lumen. Immunoelectron microscopy demonstrated that OBAP was confined to the mitochondrial inner membrane within parietal cells and that the number of mitochondria in the upper and lower parts of the gastric epithelium was significantly larger than the number in the middle part of the gastric epithelium. Based on the results, it was concluded that OBAP is mainly produced by mitochondria of parietal cells in the upper and lower parts of the gastric epithelium. Moreover, the presence of OBAP in the gastric gland lumen suggests an exocrine mechanism of release. Copyright © 2015 Elsevier GmbH. All rights reserved.

  2. LUMINOUS SATELLITES. II. SPATIAL DISTRIBUTION, LUMINOSITY FUNCTION, AND COSMIC EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Nierenberg, A. M.; Treu, T. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Auger, M. W. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB30HA (United Kingdom); Marshall, P. J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Fassnacht, C. D. [Department of Physics, University of California, Davis, CA 95616 (United States); Busha, Michael T., E-mail: amn01@physics.ucsb.edu [Institute for Theoretical Physics, University of Zuerich, Zuerich (Switzerland)

    2012-06-20

    We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log{sub 10}[M*{sub h}/M{sub Sun }] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R){proportional_to}R{sup {gamma}{sub p}}, we find {gamma}{sub p} = -1.1 {+-} 0.3. We find no dependency of {gamma}{sub p} on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

  3. Timing and Spatial Distribution of Loess in Xinjiang, NW China.

    Directory of Open Access Journals (Sweden)

    Yun Li

    Full Text Available Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess-paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to 670 m. The variation trend of the sand fraction (>63 μm grain-size contour can indicate the local major wind directions, so we conclude that the NW and NE winds are the main wind directions in the North and South Xinjiang, and the westerly wind mainly transport dust into the Ili basin. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.

  4. Spatial distribution of soda straws growth rates of the Coufin Cave (Vercors, France

    Directory of Open Access Journals (Sweden)

    Perrette Yves

    2010-07-01

    Full Text Available The Choranche Cave system (Vercors, France is an excellent locality for measuring the growth rates of large numbers soda straws. This is especially the case for the Coufin Cave, as enlargement of the cave entrance in 1875 led to a change in stalactite color from brown to white, thus providing a reliable chronomarker. The date of this brown-to-white calcite transition has been confirmed by lamina counting. We measured and georeferenced the growth-lengths of 306 soda straws in a 1m2 area of the roof of the Coufin Cave entrance chamber. Because of the very slow and sometimes inexistent water feeding of those stalactites, hydrochemistry analysis were not achieved and drop rate effect on growth were neglected; this study is based on a geomorphological and geostatistical work. By measuring a large number of soda straws in a very small area for which most of the parameters affecting stalactite growth could be considered uniform, and because flow rates are very slow (frequencies are always superior to 1 drop per half hour, we could ascribe differences in growth rates to variations in the global increase of water flow through the unsaturated matrix. Statistical and geostatistical analyses of the measurements showed that this set of similarly shaped stalactites actually consisted of three Gaussian populations with different mean growth rates: fast growth rate (FGR- mean of 0.92 mm.y-1, medium growth rate (MGR- mean of 0.47 mm.y-1 and low growth rate (LGR- 0.09 mm.y-1. Plotting the lengths and spatial distribution of the 20 longest FGR soda straws revealed that there is a rough pattern to the water flow through the cave roof. Even if no direction is statisticaly different from others, the observed directional pattern is consistent with local and regional tectonic observations. Plots of the spatial distribution of the soda straws show that FGR soda straws follow lines of regional geological stress, whereas MGR and LGR soda straws are more dispersed.

  5. A novel spatial performance metric for robust pattern optimization of distributed hydrological models

    Science.gov (United States)

    Stisen, S.; Demirel, C.; Koch, J.

    2017-12-01

    Evaluation of performance is an integral part of model development and calibration as well as it is of paramount importance when communicating modelling results to stakeholders and the scientific community. There exists a comprehensive and well tested toolbox of metrics to assess temporal model performance in the hydrological modelling community. On the contrary, the experience to evaluate spatial performance is not corresponding to the grand availability of spatial observations readily available and to the sophisticate model codes simulating the spatial variability of complex hydrological processes. This study aims at making a contribution towards advancing spatial pattern oriented model evaluation for distributed hydrological models. This is achieved by introducing a novel spatial performance metric which provides robust pattern performance during model calibration. The promoted SPAtial EFficiency (spaef) metric reflects three equally weighted components: correlation, coefficient of variation and histogram overlap. This multi-component approach is necessary in order to adequately compare spatial patterns. spaef, its three components individually and two alternative spatial performance metrics, i.e. connectivity analysis and fractions skill score, are tested in a spatial pattern oriented model calibration of a catchment model in Denmark. The calibration is constrained by a remote sensing based spatial pattern of evapotranspiration and discharge timeseries at two stations. Our results stress that stand-alone metrics tend to fail to provide holistic pattern information to the optimizer which underlines the importance of multi-component metrics. The three spaef components are independent which allows them to complement each other in a meaningful way. This study promotes the use of bias insensitive metrics which allow comparing variables which are related but may differ in unit in order to optimally exploit spatial observations made available by remote sensing

  6. A model for the spatial distribution of snow water equivalent parameterized from the spatial variability of precipitation

    Directory of Open Access Journals (Sweden)

    T. Skaugen

    2016-09-01

    Full Text Available Snow is an important and complicated element in hydrological modelling. The traditional catchment hydrological model with its many free calibration parameters, also in snow sub-models, is not a well-suited tool for predicting conditions for which it has not been calibrated. Such conditions include prediction in ungauged basins and assessing hydrological effects of climate change. In this study, a new model for the spatial distribution of snow water equivalent (SWE, parameterized solely from observed spatial variability of precipitation, is compared with the current snow distribution model used in the operational flood forecasting models in Norway. The former model uses a dynamic gamma distribution and is called Snow Distribution_Gamma, (SD_G, whereas the latter model has a fixed, calibrated coefficient of variation, which parameterizes a log-normal model for snow distribution and is called Snow Distribution_Log-Normal (SD_LN. The two models are implemented in the parameter parsimonious rainfall–runoff model Distance Distribution Dynamics (DDD, and their capability for predicting runoff, SWE and snow-covered area (SCA is tested and compared for 71 Norwegian catchments. The calibration period is 1985–2000 and validation period is 2000–2014. Results show that SD_G better simulates SCA when compared with MODIS satellite-derived snow cover. In addition, SWE is simulated more realistically in that seasonal snow is melted out and the building up of "snow towers" and giving spurious positive trends in SWE, typical for SD_LN, is prevented. The precision of runoff simulations using SD_G is slightly inferior, with a reduction in Nash–Sutcliffe and Kling–Gupta efficiency criterion of 0.01, but it is shown that the high precision in runoff prediction using SD_LN is accompanied with erroneous simulations of SWE.

  7. Study on spatial resolution improvement of distributed temperature sensor system by linear fitting algorithm

    Science.gov (United States)

    Sun, Miao; Tang, Yuquan; Li, Jun; Yang, Shuang; Dong, Fengzhong

    2015-10-01

    Spatial resolution determines the minimum space unit that a distributed temperature sensor system can distinguish along the fiber thus it is an important parameter to evaluate the performance of the distributed temperature sensor system. A typical distributed temperature sensor system with a spatial resolution of 5m is built and an algorithm of linear fitting correction is proposed to realize temperature measurement of fiber length shorter than 5m accurately. With the method of linear fitting correction, the spatial resolution of the distributed temperature sensor system has been improved from 5m to 1m. The measured temperature of the DTS system is well calibrated by using linear fitting correction algorithm with a fiber length of 4m, 3m, 2m and 1m respectively. The maximum error of the corrective temperature is 2° for long term measurement.

  8. Temporal and spatial distribution of human cryptosporidiosis in the west of Ireland 2004-2007

    Directory of Open Access Journals (Sweden)

    Cloughley Richard

    2009-11-01

    Full Text Available Abstract Background Cryptosporidiosis is increasingly recognised as a cause of gastrointestinal infection in Ireland and has been implicated in several outbreaks. This study aimed to investigate the spatial and temporal distribution of human cryptosporidiosis in the west of Ireland in order to identify high risk seasons and areas and to compare Classically Calculated (CC and Empirical Bayesian (EB incidence rates. Two spatial scales of analysis were used with a view to identifying the best one in assessing geographical patterns of infection. Global Moran's I and Local Moran's I tests of autocorrelation were used to test for evidence of global and local spatial clustering. Results There were statistically significant seasonal patterns of cryptosporidiosis with peaks in spring and an increasing temporal trend. Significant (p Conclusion This study identified spatial and temporal patterns in cryptosporidiosis distribution. The study also showed benefit in performing spatial analyses at more than one spatial scale to assess geographical patterns in disease distribution and that smoothing of disease rates for mapping in small areas enhances visualisation of spatial patterns. These findings are relevant in guiding policy decisions on disease control strategies.

  9. Improved Shape Parameter Estimation in Pareto Distributed Clutter with Neural Networks

    Directory of Open Access Journals (Sweden)

    José Raúl Machado-Fernández

    2016-12-01

    Full Text Available The main problem faced by naval radars is the elimination of the clutter input which is a distortion signal appearing mixed with target reflections. Recently, the Pareto distribution has been related to sea clutter measurements suggesting that it may provide a better fit than other traditional distributions. The authors propose a new method for estimating the Pareto shape parameter based on artificial neural networks. The solution achieves a precise estimation of the parameter, having a low computational cost, and outperforming the classic method which uses Maximum Likelihood Estimates (MLE. The presented scheme contributes to the development of the NATE detector for Pareto clutter, which uses the knowledge of clutter statistics for improving the stability of the detection, among other applications.

  10. Temporal and spatial distribution of human cryptosporidiosis in the west of Ireland 2004-2007.

    LENUS (Irish Health Repository)

    Callaghan, Mary

    2009-01-01

    BACKGROUND: Cryptosporidiosis is increasingly recognised as a cause of gastrointestinal infection in Ireland and has been implicated in several outbreaks. This study aimed to investigate the spatial and temporal distribution of human cryptosporidiosis in the west of Ireland in order to identify high risk seasons and areas and to compare Classically Calculated (CC) and Empirical Bayesian (EB) incidence rates. Two spatial scales of analysis were used with a view to identifying the best one in assessing geographical patterns of infection. Global Moran\\'s I and Local Moran\\'s I tests of autocorrelation were used to test for evidence of global and local spatial clustering. RESULTS: There were statistically significant seasonal patterns of cryptosporidiosis with peaks in spring and an increasing temporal trend. Significant (p < 0.05) global spatial clustering was observed in CC rates at the Electoral Division (ED) level but not in EB rates at the same level. Despite variations in disease, ED level was found to provide the most accurate account of distribution of cryptosporidiosis in the West of Ireland but required spatial EB smoothing of cases. There were a number of areas identified with significant local clustering of cryptosporidiosis rates. CONCLUSION: This study identified spatial and temporal patterns in cryptosporidiosis distribution. The study also showed benefit in performing spatial analyses at more than one spatial scale to assess geographical patterns in disease distribution and that smoothing of disease rates for mapping in small areas enhances visualisation of spatial patterns. These findings are relevant in guiding policy decisions on disease control strategies.

  11. Spatial tissue distribution of polyacetylenes in carrot root.

    Science.gov (United States)

    Baranska, Malgorzata; Schulz, Hartwig

    2005-06-01

    The presented results show the usefulness of Raman spectroscopy in the investigation of polyacetylenes in carrot root. The components are measured directly in the plant tissue without any preliminary sample preparation. Compared with the strong polyacetylene signals the spectral impact of the surrounding biological matrix is weak, except for carotenoids, and therefore it does not contribute significantly to the obtained results. Three different Raman mapping techniques applied here have revealed essential information about the investigated compounds. Using point acquisition several spectra have been measured to demonstrate the complex composition of the polyacetylene fraction in carrot root. The molecular structures of falcarinol, falcarindiol and falcarindiol 3-acetate are similar but their Raman spectra exhibit differences demonstrated by the shift of their -C triple bond C- mode. Line mapping performed along the diameter of transversely cut carrot roots has been used to investigate the relative concentration of polyacetylenes and carotenoids. An area map provides detailed information regarding the distribution of both components. It has been found that high accumulation of polyacetylenes is located in the outer section of the root, namely the pericyclic parenchyma, and in the phloem part close to the secondary cambium. The highest concentration of carotenes is seen in the immediate vicinity to polyacetylene conglomerates.

  12. Luminescent Sensors for Tracking Spatial Particle Distribution in an Explosion

    Science.gov (United States)

    Eilers, Hergen; Gunawidjaja, Ray; Diez-Y-Riega, Helena; Svingala, Forrest; Daniels, Amber; Lightstone, James; Washington State University Collaboration; Nswc Iheodtd Collaboration

    2015-06-01

    We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 orp-Eu:ZrO2/c-Tb:Y2O3. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 365 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference. Defense Threat Reduction Agency, HDTRA1-10-1-0005.

  13. Nonfeedback Distributed Beamforming Using Spatial-Temporal Extraction

    Directory of Open Access Journals (Sweden)

    Pongnarin Sriploy

    2016-01-01

    Full Text Available So far, major phase synchronization techniques for distributed beamforming suffer from the problem related to the feedback procedure as a base station has to send the feedback reference signal back to the transmitting nodes. This requires stability of communication channel or a number of retransmissions, introducing a complicated system to both transmitter and receiver. Therefore, this paper proposes an alternative technique, so-called nonfeedback beamforming, employing an operation in both space and time domains. The proposed technique is to extract a combined signal at the base station. The concept of extraction is based on solving a simultaneous linear equation without the requirement of feedback or reference signals from base station. Also, the number of retransmissions is less compared with the ones available in literatures. As a result, the transmitting nodes are of low complexity and also low power consumption. The simulation and experimental results reveal that the proposed technique provides the optimum beamforming gain. Furthermore, it can reduce Bit Error Rate to the systems.

  14. Mapping the spatial distribution of global anthropogenic mercury atmospheric emission inventories

    Science.gov (United States)

    Wilson, Simon J.; Steenhuisen, Frits; Pacyna, Jozef M.; Pacyna, Elisabeth G.

    This paper describes the procedures employed to spatially distribute global inventories of anthropogenic emissions of mercury to the atmosphere, prepared by Pacyna, E.G., Pacyna, J.M., Steenhuisen, F., Wilson, S. [2006. Global anthropogenic mercury emission inventory for 2000. Atmospheric Environment, this issue, doi:10.1016/j.atmosenv.2006.03.041], and briefly discusses the results of this work. A new spatially distributed global emission inventory for the (nominal) year 2000, and a revised version of the 1995 inventory are presented. Emissions estimates for total mercury and major species groups are distributed within latitude/longitude-based grids with a resolution of 1×1 and 0.5×0.5°. A key component in the spatial distribution procedure is the use of population distribution as a surrogate parameter to distribute emissions from sources that cannot be accurately geographically located. In this connection, new gridded population datasets were prepared, based on the CEISIN GPW3 datasets (CIESIN, 2004. Gridded Population of the World (GPW), Version 3. Center for International Earth Science Information Network (CIESIN), Columbia University and Centro Internacional de Agricultura Tropical (CIAT). GPW3 data are available at http://beta.sedac.ciesin.columbia.edu/gpw/index.jsp). The spatially distributed emissions inventories and population datasets prepared in the course of this work are available on the Internet at www.amap.no/Resources/HgEmissions/

  15. Cooperation in carbon source degradation shapes spatial self-organization of microbial consortia on hydrated surfaces.

    Science.gov (United States)

    Tecon, Robin; Or, Dani

    2017-03-06

    Mounting evidence suggests that natural microbial communities exhibit a high level of spatial organization at the micrometric scale that facilitate ecological interactions and support biogeochemical cycles. Microbial patterns are difficult to study definitively in natural environments due to complex biodiversity, observability and variable physicochemical factors. Here, we examine how trophic dependencies give rise to self-organized spatial patterns of a well-defined bacterial consortium grown on hydrated surfaces. The model consortium consisted of two Pseudomonas putida mutant strains that can fully degrade the aromatic hydrocarbon toluene. We demonstrated that obligate cooperation in toluene degradation (cooperative mutualism) favored convergence of 1:1 partner ratio and strong intermixing at the microscale (10-100 μm). In contrast, competition for benzoate, a compound degraded independently by both strains, led to distinct segregation patterns. Emergence of a persistent spatial pattern has been predicted for surface attached microbial activity in liquid films that mediate diffusive exchanges while permitting limited cell movement (colony expansion). This study of a simple microbial consortium offers mechanistic glimpses into the rules governing the assembly and functioning of complex sessile communities, and points to general principles of spatial organization with potential applications for natural and engineered microbial systems.

  16. Hierarchical spatial models for predicting pygmy rabbit distribution and relative abundance

    Science.gov (United States)

    Wilson, T.L.; Odei, J.B.; Hooten, M.B.; Edwards, T.C.

    2010-01-01

    Conservationists routinely use species distribution models to plan conservation, restoration and development actions, while ecologists use them to infer process from pattern. These models tend to work well for common or easily observable species, but are of limited utility for rare and cryptic species. This may be because honest accounting of known observation bias and spatial autocorrelation are rarely included, thereby limiting statistical inference of resulting distribution maps. We specified and implemented a spatially explicit Bayesian hierarchical model for a cryptic mammal species (pygmy rabbit Brachylagus idahoensis). Our approach used two levels of indirect sign that are naturally hierarchical (burrows and faecal pellets) to build a model that allows for inference on regression coefficients as well as spatially explicit model parameters. We also produced maps of rabbit distribution (occupied burrows) and relative abundance (number of burrows expected to be occupied by pygmy rabbits). The model demonstrated statistically rigorous spatial prediction by including spatial autocorrelation and measurement uncertainty. We demonstrated flexibility of our modelling framework by depicting probabilistic distribution predictions using different assumptions of pygmy rabbit habitat requirements. Spatial representations of the variance of posterior predictive distributions were obtained to evaluate heterogeneity in model fit across the spatial domain. Leave-one-out cross-validation was conducted to evaluate the overall model fit. Synthesis and applications. Our method draws on the strengths of previous work, thereby bridging and extending two active areas of ecological research: species distribution models and multi-state occupancy modelling. Our framework can be extended to encompass both larger extents and other species for which direct estimation of abundance is difficult. ?? 2010 The Authors. Journal compilation ?? 2010 British Ecological Society.

  17. Effects of flooding on the spatial distribution of soil seed and spore banks of native grasslands of the Pantanal wetland

    Directory of Open Access Journals (Sweden)

    Patricia Carla de Oliveira

    2015-09-01

    Full Text Available ABSTRACTTo better understand the role that flooding plays in shaping plant communities of native floodable grasslands of the Pantanal and to characterize the spatial distribution of plants, we present the results of a survey of soil seed and spore banks using the seedling emergence method. We hypothesized that terrain subjected to the deepest and longest flooding should have higher propagule abundance and richness. The species composition and distribution of seeds and spores in the soil were assessed at five sites using three sampling positions at each according to inundation intensity. In each sample position 2cm-thick soil samples were collected in quadrats to a depth of 10cm. Litter was also collected as an independent layer. Sample monitoring in the greenhouse resulted in the emergence of 5489 seedlings, or 6353 propagules.m-2. Both the litter layer and the deepest soil layer had low abundances. A total of forty-four morphospecies (16 families were recorded. Both seedling abundance and species richness were concentrated in the more floodable center sections. Isoetes pedersenii, Eleocharis minima, Sagittaria guayanensis, Rotala mexicana, Eleocharis plicarhachis, and Panicum laxum were the most abundant species. The species composition and spatial distribution of the propagule bank suggests that flooding plays a crucial role in seasonal vegetation dynamics in Pantanal wetlands, mediated by the ability of the soil to host seeds and spores during dry season.

  18. Crop yield response to climate change varies with crop spatial distribution pattern.

    Science.gov (United States)

    Leng, Guoyong; Huang, Maoyi

    2017-05-03

    The linkage between crop yield and climate variability has been confirmed in numerous studies using statistical approaches. A crucial assumption in these studies is that crop spatial distribution pattern is constant over time. Here, we explore how changes in county-level corn spatial distribution pattern modulate the response of its yields to climate change at the state level over the Contiguous United States. Our results show that corn yield response to climate change varies with crop spatial distribution pattern, with distinct impacts on the magnitude and even the direction at the state level. Corn yield is predicted to decrease by 20~40% by 2050 s when considering crop spatial distribution pattern changes, which is 6~12% less than the estimates with fixed cropping pattern. The beneficial effects are mainly achieved by reducing the negative impacts of daily maximum temperature and strengthening the positive impacts of precipitation. Our results indicate that previous empirical studies could be biased in assessing climate change impacts by ignoring the changes in crop spatial distribution pattern. This has great implications for understanding the increasing debates on whether climate change will be a net gain or loss for regional agriculture.

  19. CA-CFAR Adjustment Factor Correction with a priori Knowledge of the Clutter Distribution Shape Parameter

    Directory of Open Access Journals (Sweden)

    José Raúl Machado-Fernández

    2017-08-01

    Full Text Available Oceanic and coastal radars operation is affected because the targets information is received mixed with and undesired contribution called sea clutter. Specifically, the popular CA-CFAR processor is incapable of maintaining its design false alarm probability when facing clutter with statistical variations. In opposition to the classic alternative suggesting the use of a fixed adjustment factor, the authors propose a modification of the CA- CFAR scheme where the factor is constantly corrected according on the background signal statistical changes. Mathematically translated as a variation in the shape parameter of the clutter distribution, the background signal changes were simulated through the Weibull, Log-Normal and K distributions, deriving expressions which allow choosing an appropriate factor for each possible statistical state. The investigation contributes to the improvement of radar detection by suggesting the application of an adaptive scheme which assumes the clutter shape parameter is known a priori. The offered mathematical expressions are valid for three false alarm probabilities and several windows sizes, covering also a wide range of clutter conditions.

  20. Nonlinear spatial focusing in random layered media by spectral pulse shaping

    Science.gov (United States)

    Han, Alex C.; Milner, Valery

    2016-02-01

    We demonstrate numerically a method of focusing two-photon fields inside one-dimensional random media. The approach is based on coherent control of backscattering achieved by adaptive spectral pulse shaping. The spectral phases of a femtosecond laser pulse are adjusted for the constructive interference of its backward-traveling components, resulting in an enhanced reflection from within the random system. A delayed forward-propagating second pulse overlaps with the controlled reflection, increasing the interpulse multiphoton field at a location determined by the delay between the two pulses. The technique is shown to be robust against the variations of the disorder and to work with realistic pulse-shaping parameters, hence enabling applications in controlling random lasing and multiphoton imaging in scattering materials.

  1. Adaptive shaping system for both spatial and temporal profiles of a highly stabilized UV laser light source for a photocathode RF gun

    Science.gov (United States)

    Tomizawa, H.; Dewa, H.; Taniuchi, T.; Mizuno, A.; Asaka, T.; Yanagida, K.; Suzuki, S.; Kobayashi, T.; Hanaki, H.; Matsui, F.

    2006-02-01

    We have been developing a stable and highly qualified ultraviolet (UV) laser pulse as a light source of an RF gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photocathode. The chirped pulse amplification (CPA) Ti:sapphire laser system is operated at a repetition rate of 10 Hz. At the third harmonic generation (central wavelength—263 nm), the laser pulse energy after a 45 cm silica rod is up to 850 μJ/pulse. In its present status, the laser's pulse energy stability has been improved down to 0.2˜0.3% at the fundamental, and 0.7-1.4% (rms; 10 pps; 33,818 shots) at the third harmonic generation, respectively. This stability has been held for 1 month continuously, 24 h a day. The improvements we had passively implemented were to stabilize the laser system as well as the environmental conditions. We introduced a humidity-control system kept at 50-60% in a clean room to reduce damage to the optics. In addition, we prepared a deformable mirror for spatial shaping and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying both the adaptive optics to automatic optimization of the electron beam bunch to produce lower emittance with the feedback routine. Before the improvements, the electron beam produced from a cathode suffered inhomogeneous distribution caused by the quantum efficiency effect, and some pulse distortions caused by its response time. However, we can now freely form any arbitrary electron beam distribution on the surface of the cathode.

  2. A Gauss-Newton method for the integration of spatial normal fields in shape Space

    KAUST Repository

    Balzer, Jonathan

    2011-08-09

    We address the task of adjusting a surface to a vector field of desired surface normals in space. The described method is entirely geometric in the sense, that it does not depend on a particular parametrization of the surface in question. It amounts to solving a nonlinear least-squares problem in shape space. Previously, the corresponding minimization has been performed by gradient descent, which suffers from slow convergence and susceptibility to local minima. Newton-type methods, although significantly more robust and efficient, have not been attempted as they require second-order Hadamard differentials. These are difficult to compute for the problem of interest and in general fail to be positive-definite symmetric. We propose a novel approximation of the shape Hessian, which is not only rigorously justified but also leads to excellent numerical performance of the actual optimization. Moreover, a remarkable connection to Sobolev flows is exposed. Three other established algorithms from image and geometry processing turn out to be special cases of ours. Our numerical implementation founds on a fast finite-elements formulation on the minimizing sequence of triangulated shapes. A series of examples from a wide range of different applications is discussed to underline flexibility and efficiency of the approach. © 2011 Springer Science+Business Media, LLC.

  3. Impact of precipitation spatial resolution on the hydrological response of an integrated distributed water resources model

    DEFF Research Database (Denmark)

    Fu, Suhua; Sonnenborg, Torben; Jensen, Karsten Høgh

    2011-01-01

    Precipitation is a key input variable to hydrological models, and the spatial variability of the input is expected to impact the hydrological response predicted by a distributed model. In this study, the effect of spatial resolution of precipitation on runoff , recharge and groundwater head...... was analyzed in the Alergaarde catchment in Denmark. Six different precipitation spatial resolutions were used as inputs to a physically based, distributed hydrological model, the MIKE SHE model. The results showed that the resolution of precipitation input had no apparent effect on annual water balance...... of the total catchment and runoff discharge hydrograph at watershed outlet. On the other hand, groundwater recharge and groundwater head were both aff ected. The impact of the spatial resolution of precipitation input is reduced with increasing catchment size. The effect on stream discharge is relatively low...

  4. Shape of growth-rate distribution determines the type of Non-Gibrat’s Property

    Science.gov (United States)

    Ishikawa, Atushi; Fujimoto, Shouji; Mizuno, Takayuki

    2011-11-01

    In this study, the authors examine exhaustive business data on Japanese firms, which cover nearly all companies in the mid- and large-scale ranges in terms of firm size, to reach several key findings on profits/sales distribution and business growth trends. Here, profits denote net profits. First, detailed balance is observed not only in profits data but also in sales data. Furthermore, the growth-rate distribution of sales has wider tails than the linear growth-rate distribution of profits in log-log scale. On the one hand, in the mid-scale range of profits, the probability of positive growth decreases and the probability of negative growth increases symmetrically as the initial value increases. This is called Non-Gibrat’s First Property. On the other hand, in the mid-scale range of sales, the probability of positive growth decreases as the initial value increases, while the probability of negative growth hardly changes. This is called Non-Gibrat’s Second Property. Under detailed balance, Non-Gibrat’s First and Second Properties are analytically derived from the linear and quadratic growth-rate distributions in log-log scale, respectively. In both cases, the log-normal distribution is inferred from Non-Gibrat’s Properties and detailed balance. These analytic results are verified by empirical data. Consequently, this clarifies the notion that the difference in shapes between growth-rate distributions of sales and profits is closely related to the difference between the two Non-Gibrat’s Properties in the mid-scale range.

  5. Prediction of the Spatial Distribution of Bovine Endemic Fluorosis Using Ordinary Kriging

    Directory of Open Access Journals (Sweden)

    Li Lin

    2015-04-01

    Full Text Available The aim of the studies was to develop an alternative method which could overcome the lack of sampling to improve the efficiency of control efforts for bovine endemic fluorosis. The spatial distribution characteristics of the disease were analysed and a prediction model for the estimation of fluorosis distribution in some districts in northwest Liaoning province in China was established. The model used ordinary kriging, and was evaluated using cross-validation. Analysis showed that the distribution of the disease was spatial autocorrelation. The prediction error of the cross-validation (ME = -0.0092, PMSE = 0.627, AKSE = 0.597, and RMSP = 1.007 and comparison with the actual disease distribution indicated that the prediction map accurately distributed bovine endemic fluorosis. It is feasible to predict bovine endemic fluorosis in the area by using ordinary kriging and limited data.

  6. [Spatial distribution of nests of Acromyrmex crassispinus (Forel) (Hymenoptera: Formicidae) in Pinus taeda plantations].

    Science.gov (United States)

    Nickele, Mariane A; Oliveira, Edilson B de; Reis Filho, Wilson; Iede, Edson T; Ribeiro, Rodrigo D

    2010-01-01

    The spatial distribution of insects is essential to perform control strategies, to improve sample techniques and to estimate economic losses. We aimed to determine the spatial distribution of nests of Acromyrmex crassispinus (Forel) in Pinus taeda plantations. The experiments were carried out in P. taeda plantations with different ages (treatments: recently-planted, three and six-year old plants). The study took place in Rio Negrinho and in Três Barras, SC. Three plots of one hectare were delimited in each treatment, and plots were divided in 64 sample units. The analysis of the dispersion index [variance/mean relationship (I), index of Morisita (Iδ) and k exponent of negative binomial distribution] showed that the majority of the samplings presented random distribution. Among the three distributions of probabilities studied: Poisson, positive binomial and negative binomial, the Poisson distribution was the best model to fit the spatial distribution of A. crassispinus nests in all samplings. The result was a random distribution in the plantings of different ages.

  7. The Impact of Spatial and Temporal Resolutions in Tropical Summer Rainfall Distribution: Preliminary Results

    Science.gov (United States)

    Liu, Q.; Chiu, L. S.; Hao, X.

    2017-10-01

    The abundance or lack of rainfall affects peoples' life and activities. As a major component of the global hydrological cycle (Chokngamwong & Chiu, 2007), accurate representations at various spatial and temporal scales are crucial for a lot of decision making processes. Climate models show a warmer and wetter climate due to increases of Greenhouse Gases (GHG). However, the models' resolutions are often too coarse to be directly applicable to local scales that are useful for mitigation purposes. Hence disaggregation (downscaling) procedures are needed to transfer the coarse scale products to higher spatial and temporal resolutions. The aim of this paper is to examine the changes in the statistical parameters of rainfall at various spatial and temporal resolutions. The TRMM Multi-satellite Precipitation Analysis (TMPA) at 0.25 degree, 3 hourly grid rainfall data for a summer is aggregated to 0.5,1.0, 2.0 and 2.5 degree and at 6, 12, 24 hourly, pentad (five days) and monthly resolutions. The probability distributions (PDF) and cumulative distribution functions(CDF) of rain amount at these resolutions are computed and modeled as a mixed distribution. Parameters of the PDFs are compared using the Kolmogrov-Smironov (KS) test, both for the mixed and the marginal distribution. These distributions are shown to be distinct. The marginal distributions are fitted with Lognormal and Gamma distributions and it is found that the Gamma distributions fit much better than the Lognormal.

  8. Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM)

    DEFF Research Database (Denmark)

    Khanmohammadi, Mahdieh; Waagepetersen, Rasmus Plenge; Sporring, Jon

    2015-01-01

    in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation towards the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs...

  9. Block scale interpretation on the spatial distribution of the fracture system in the study sites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Su; Bae, Dae Seok; Kim, Chun Soo; Koh, Yong Kweon; Kim, Geon Young [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-05-01

    The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures in rock mass. This study aims to characterize the spatial distribution characteristics of regional lineaments and background fracture system in eastern and western-type granite rock mass. The spatial distribution characteristics of the fracture system around 500m depth has been estimated based on the homogeneous discontinuity domain except for the highly fractured upper zone. 6 refs., 16 figs., 7 tabs. (Author)

  10. Efficiency analysis of control algorithms in spatially distributed systems with chaotic behavior

    Directory of Open Access Journals (Sweden)

    Korus Łukasz

    2014-12-01

    Full Text Available The paper presents results of examination of control algorithms for the purpose of controlling chaos in spatially distributed systems like the coupled map lattice (CML. The mathematical definition of the CML, stability analysis as well as some basic results of numerical simulation exposing complex, spatiotemporal and chaotic behavior of the CML were already presented in another paper. The main purpose of this article is to compare the efficiency of controlling chaos by simple classical algorithms in spatially distributed systems like CMLs. This comparison is made based on qualitative and quantitative evaluation methods proposed in the previous paper such as the indirect Lyapunov method, Lyapunov exponents and the net direction phase indicator. As a summary of this paper, some conclusions which can be useful for creating a more efficient algorithm of controlling chaos in spatially distributed systems are made.

  11. Spatial root distribution of plants growing in vertical media for use in living walls

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Dresbøll, Dorte Bodin; Thorup-Kristensen, Kristian

    2014-01-01

    Background and Aims: For plants growing in living walls, the growth potential is correlated to the roots ability to utilize resources in all parts of the growing medium and thereby to the spatial root distribution. The aim of the study was to test how spatial root distribution was affected...... of rockwool) in transparent boxes under greenhouse conditions. Root frequency was registered and the activity of individual root systems was studied via 15N uptake and plant dry weight was measured. Results: Plants in coir had stronger root growth in all parts of the medium than plants in rockwool. Upwards...... root growth was limited for plants in the middle or lower parts of the medium and 15N measurements confirmed that only plants in the bottom of the box had active roots in the bottom of the medium. The species differed in root architecture and spatial root distribution. Conclusions: The choice...

  12. Lookup Tables-based mean level detection of spatially distributed targets in non Gaussian clutter

    Directory of Open Access Journals (Sweden)

    Nabila Nouar

    2017-08-01

    Full Text Available In this paper, Constant False Alarm Rate (CFAR detection of spatially distributed targets embedded in compound Gaussian clutter with Inverse Gamma texture is addressed. By taking into account the fact that clutter parameters are unknown in practical situations, we propose mean level based on Lookup Tables detectors, that operate as a two-step approach, which consists of computing threshold factors that maintain a Constant Probability of False Alarm (Pfa using intensive Monte Carlo simulations, and storing these factors in Lookup Tables, this first step is done independently from the detection algorithm. Then, at the detection stage, the detectors structure is associated to the Maximum Likelihood (ML estimation technique to estimate the shape and the scale parameters, and compare them to the closest integer and half integer values in the Lookup Tables, to select the suitable threshold factor. Under the High Resolution Radar (HRR assumption, the target is spread over a number of cells according to the Multiple Dominant scattering centers (MDS representation. The binary total binary hypothesis tests are derived using the expression of the overall target energy, which is computed as the sum of the energies reflected from each cell. Performance analysis of the proposed detectors is carried out using Monte Carlo simulation for various couples of clutter parameters and MDS models, and are compared to those of the Cell Averaging Based on Lookup Tables detector (CA-LT. In order to assess the performances of the proposed detectors in terms of the radar resolution, their performances are compared to the case of point-like targets.

  13. Moving beyond abundance distributions: neutral theory and spatial patterns in a tropical forest.

    Science.gov (United States)

    May, Felix; Huth, Andreas; Wiegand, Thorsten

    2015-03-07

    Assessing the relative importance of different processes that determine the spatial distribution of species and the dynamics in highly diverse plant communities remains a challenging question in ecology. Previous modelling approaches often focused on single aggregated forest diversity patterns that convey limited information on the underlying dynamic processes. Here, we use recent advances in inference for stochastic simulation models to evaluate the ability of a spatially explicit and spatially continuous neutral model to quantitatively predict six spatial and non-spatial patterns observed at the 50 ha tropical forest plot on Barro Colorado Island, Panama. The patterns capture different aspects of forest dynamics and biodiversity structure, such as annual mortality rate, species richness, species abundance distribution, beta-diversity and the species-area relationship (SAR). The model correctly predicted each pattern independently and up to five patterns simultaneously. However, the model was unable to match the SAR and beta-diversity simultaneously. Our study moves previous theory towards a dynamic spatial theory of biodiversity and demonstrates the value of spatial data to identify ecological processes. This opens up new avenues to evaluate the consequences of additional process for community assembly and dynamics.

  14. Analysis of shifts in the spatial distribution of vegetation due to climate change

    Science.gov (United States)

    del Jesus, Manuel; Díez-Sierra, Javier; Rinaldo, Andrea; Rodríguez-Iturbe, Ignacio

    2017-04-01

    Climate change will modify the statistical regime of most climatological variables, inducing changes on average values and in the natural variability of environmental variables. These environmental variables may be used to explain the spatial distribution of functional types of vegetation in arid and semiarid watersheds through the use of plant optimization theories. Therefore, plant optimization theories may be used to approximate the response of the spatial distribution of vegetation to a changing climate. Predicting changes in these spatial distributions is important to understand how climate change may affect vegetated ecosystems, but it is also important for hydrological engineering applications where climate change effects on water availability are assessed. In this work, Maximum Entropy Production (MEP) is used as the plant optimization theory that describes the spatial distribution of functional types of vegetation. Current climatological conditions are obtained from direct observations from meteorological stations. Climate change effects are evaluated for different temporal horizons and different climate change scenarios using numerical model outputs from the CMIP5. Rainfall estimates are downscaled by means of a stochastic point process used to model rainfall. The study is carried out for the Rio Salado watershed, located within the Sevilleta LTER site, in New Mexico (USA). Results show the expected changes in the spatial distribution of vegetation and allow to evaluate the expected variability of the changes. The updated spatial distributions allow to evaluate the vegetated ecosystem health and its updated resilience. These results can then be used to inform the hydrological modeling part of climate change assessments analyzing water availability in arid and semiarid watersheds.

  15. Determinants of spatial distribution in a bee community: nesting resources, flower resources, and body size.

    Directory of Open Access Journals (Sweden)

    Anna Torné-Noguera

    Full Text Available Understanding biodiversity distribution is a primary goal of community ecology. At a landscape scale, bee communities are affected by habitat composition, anthropogenic land use, and fragmentation. However, little information is available on local-scale spatial distribution of bee communities within habitats that are uniform at the landscape scale. We studied a bee community along with floral and nesting resources over a 32 km2 area of uninterrupted Mediterranean scrubland. Our objectives were (i to analyze floral and nesting resource composition at the habitat scale. We ask whether these resources follow a geographical pattern across the scrubland at bee-foraging relevant distances; (ii to analyze the distribution of bee composition across the scrubland. Bees being highly mobile organisms, we ask whether bee composition shows a homogeneous distribution or else varies spatially. If so, we ask whether this variation is irregular or follows a geographical pattern and whether bees respond primarily to flower or to nesting resources; and (iii to establish whether body size influences the response to local resource availability and ultimately spatial distribution. We obtained 6580 specimens belonging to 98 species. Despite bee mobility and the absence of environmental barriers, our bee community shows a clear geographical pattern. This pattern is mostly attributable to heterogeneous distribution of small (<55 mg species (with presumed smaller foraging ranges, and is mostly explained by flower resources rather than nesting substrates. Even then, a large proportion (54.8% of spatial variability remains unexplained by flower or nesting resources. We conclude that bee communities are strongly conditioned by local effects and may exhibit spatial heterogeneity patterns at a scale as low as 500-1000 m in patches of homogeneous habitat. These results have important implications for local pollination dynamics and spatial variation of plant-pollinator networks.

  16. Spatial distribution and density of dolines in the southeastern Velebit area

    Directory of Open Access Journals (Sweden)

    Jelena Marković

    2016-01-01

    Full Text Available Dolines are considered to be among the most prominent karst formations, which is why they can serve as diagnostic forms of karst. Their spatial distribution and density are important indicators of an area’s degree of karstification, as well as of an overall geomorphological development. The aim of this paper is to determine the spatial distribution and the density of dolines, and also to analyse the influence of geological structure and morphometric features of the terrain (hypsometry, slope inclination, relative relief on the spatial distribution of dolines in the area of southeastern Velebit. Moreover, for the first time with regards to the Croatian karst, the spatial distribution of dolines was compared with the spatial distribution of entrances into caves in the southeastern Velebit’s area of Crnopac. The data on the dolines’ position were adopted from 1:25,000 scaled topographic maps. All data were digitalised and analysed with ArcGIS 10.1 software in the GIS laboratory of the Geographic Department of the Faculty of Science in Zagreb. The research showed a strong influence of morphometric parameters of the relief on dolines’ density. The most prominent occurrence of dolines is linked with the areas ranging from 1000 to 1200 meters of altitude, slope inclination lower than 2° and the relative relief of 100 – 200 m per km2. Furthermore, the highest density of dolines was recorded in the Jurassic carbonate layers, while it was determined that the zones of main faults do not have a significant influence on the increase of dolines’ density. A high degree of correlation was determined by comparing spatial distributions and density of dolines and entrances into caves.

  17. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

    Science.gov (United States)

    Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

    2015-09-23

    The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  18. Optimization of spatial light distribution through genetic algorithms for vision systems applied to quality control

    International Nuclear Information System (INIS)

    Castellini, P; Cecchini, S; Stroppa, L; Paone, N

    2015-01-01

    The paper presents an adaptive illumination system for image quality enhancement in vision-based quality control systems. In particular, a spatial modulation of illumination intensity is proposed in order to improve image quality, thus compensating for different target scattering properties, local reflections and fluctuations of ambient light. The desired spatial modulation of illumination is obtained by a digital light projector, used to illuminate the scene with an arbitrary spatial distribution of light intensity, designed to improve feature extraction in the region of interest. The spatial distribution of illumination is optimized by running a genetic algorithm. An image quality estimator is used to close the feedback loop and to stop iterations once the desired image quality is reached. The technique proves particularly valuable for optimizing the spatial illumination distribution in the region of interest, with the remarkable capability of the genetic algorithm to adapt the light distribution to very different target reflectivity and ambient conditions. The final objective of the proposed technique is the improvement of the matching score in the recognition of parts through matching algorithms, hence of the diagnosis of machine vision-based quality inspections. The procedure has been validated both by a numerical model and by an experimental test, referring to a significant problem of quality control for the washing machine manufacturing industry: the recognition of a metallic clamp. Its applicability to other domains is also presented, specifically for the visual inspection of shoes with retro-reflective tape and T-shirts with paillettes. (paper)

  19. A spatial pattern analysis of the halophytic species distribution in an arid coastal environment.

    Science.gov (United States)

    Badreldin, Nasem; Uria-Diez, J; Mateu, J; Youssef, Ali; Stal, Cornelis; El-Bana, Magdy; Magdy, Ahmed; Goossens, Rudi

    2015-05-01

    Obtaining information about the spatial distribution of desert plants is considered as a serious challenge for ecologists and environmental modeling due to the required intensive field work and infrastructures in harsh and remote arid environments. A new method was applied for assessing the spatial distribution of the halophytic species (HS) in an arid coastal environment. This method was based on the object-based image analysis for a high-resolution Google Earth satellite image. The integration of the image processing techniques and field work provided accurate information about the spatial distribution of HS. The extracted objects were based on assumptions that explained the plant-pixel relationship. Three different types of digital image processing techniques were implemented and validated to obtain an accurate HS spatial distribution. A total of 2703 individuals of the HS community were found in the case study, and approximately 82% were located above an elevation of 2 m. The micro-topography exhibited a significant negative relationship with pH and EC (r = -0.79 and -0.81, respectively, p < 0.001). The spatial structure was modeled using stochastic point processes, in particular a hybrid family of Gibbs processes. A new model is proposed that uses a hard-core structure at very short distances, together with a cluster structure in short-to-medium distances and a Poisson structure for larger distances. This model was found to fit the data perfectly well.

  20. Topology-induced spatial Bose-Einstein condensation for bosons on star-shaped optical networks

    International Nuclear Information System (INIS)

    Brunelli, I; Giusiano, G; Mancini, F P; Sodano, P; Trombettoni, A

    2004-01-01

    New coherent states may be induced by pertinently engineering the topology of a network. As an example, we consider the properties of non-interacting bosons on a star network, which may be realized with a dilute atomic gas in a star-shaped deep optical lattice. The ground state is localized around the star centre and it is macroscopically occupied below the Bose-Einstein condensation temperature T c . We show that T c depends only on the number of the star arms and on the Josephson energy of the bosonic Josephson junctions and that the non-condensate fraction is simply given by the reduced temperature T/T c

  1. Evaluating Bayesian spatial methods for modelling species distributions with clumped and restricted occurrence data.

    Directory of Open Access Journals (Sweden)

    David W Redding

    Full Text Available Statistical approaches for inferring the spatial distribution of taxa (Species Distribution Models, SDMs commonly rely on available occurrence data, which is often clumped and geographically restricted. Although available SDM methods address some of these factors, they could be more directly and accurately modelled using a spatially-explicit approach. Software to fit models with spatial autocorrelation parameters in SDMs are now widely available, but whether such approaches for inferring SDMs aid predictions compared to other methodologies is unknown. Here, within a simulated environment using 1000 generated species' ranges, we compared the performance of two commonly used non-spatial SDM methods (Maximum Entropy Modelling, MAXENT and boosted regression trees, BRT, to a spatial Bayesian SDM method (fitted using R-INLA, when the underlying data exhibit varying combinations of clumping and geographic restriction. Finally, we tested how any recommended methodological settings designed to account for spatially non-random patterns in the data impact inference. Spatial Bayesian SDM method was the most consistently accurate method, being in the top 2 most accurate methods in 7 out of 8 data sampling scenarios. Within high-coverage sample datasets, all methods performed fairly similarly. When sampling points were randomly spread, BRT had a 1-3% greater accuracy over the other methods and when samples were clumped, the spatial Bayesian SDM method had a 4%-8% better AUC score. Alternatively, when sampling points were restricted to a small section of the true range all methods were on average 10-12% less accurate, with greater variation among the methods. Model inference under the recommended settings to account for autocorrelation was not impacted by clumping or restriction of data, except for the complexity of the spatial regression term in the spatial Bayesian model. Methods, such as those made available by R-INLA, can be successfully used to account

  2. Spatial oxygen distribution and nitrous oxide emissions from soil after manure application

    DEFF Research Database (Denmark)

    Zhu, Kun; Bruun, Sander; Larsen, Morten

    2014-01-01

    The availability and spatial distribution of oxygen (O2) in agricultural soil are controlling factors in the production and emission of nitrous oxide (N2O) to the atmosphere, but most experiments investigating the effects of various factors on N2O emissions in soil have been conducted without...... anoxia. Nitrous oxide emissions increased immediately after depletion of O2 in the manure-amended treatments. Greater understanding and improved knowledge of the spatial distribution of O2 is clearly beneficial and can be used to devise improved application strategies for mitigating N2O emissions from...

  3. Monofractal and multifractal analysis of the spatial distribution of earthquakes in the central zone of Chile.

    Science.gov (United States)

    Pastén, Denisse; Muñoz, Víctor; Cisternas, Armando; Rogan, José; Valdivia, Juan Alejandro

    2011-12-01

    Statistical and fractal properties of the spatial distribution of earthquakes in the central zone of Chile are studied. In particular, data are shown to behave according to the well-known Gutenberg-Richter law. The fractal structure is evident for epicenters, not for hypocenters. The multifractal spectrum is also determined, both for the spatial distribution of epicenters and hypocenters. For negative values of the index of multifractal measure q, the multifractal spectrum, which usually cannot be reliably found from data, is calculated from a generalized Cantor-set model, which fits the multifractal spectrum for q > 0, a technique which has been previously applied for analysis of solar wind data.

  4. Spatial distribution of major and trace elements in bladder and kidney stones

    International Nuclear Information System (INIS)

    Chaudhri, M.A.; Watling, J.; Khan, F.A.

    2007-01-01

    The spatial distribution of major and trace elements has been studied in a range of human kidney and bladder stones with well documented histories to understand their initiation and formation. The stones were cut in half using a clean diamond saw and further cleaned, to remove surface contamination, in an ultrasonic bath. The cut surfaces were analyzed using laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS). The spatial distribution of Li, B, Mg, Al, P, Ca, Cr, Mn, Zn, Rb, Sr, Ba and Pb has been determined across the width of each stone. (author)

  5. Spatial distribution of transgenic protein after gene electrotransfer to porcine muscle

    DEFF Research Database (Denmark)

    Spanggaard, Iben; Corydon, Thomas Juhl; Hojman, Pernille

    2012-01-01

    Abstract Gene electrotransfer is an effective nonviral technique for delivery of plasmid DNA into tissues. From a clinical perspective, muscle is an attractive target tissue as long-term, high-level transgenic expression can be achieved. Spatial distribution of the transgenic protein following gene...... each transfection site in order to examine the spatial distribution of the transgenic product. We found a significantly higher luciferase activity in biopsies from the center of the transfection site compared to biopsies taken adjacent to the center, 1 and 2 cm along muscle fiber orientation (p...

  6. Shape up or ship out: migratory behaviour predicts morphology across spatial scale in a freshwater fish.

    Science.gov (United States)

    Chapman, Ben B; Hulthén, Kaj; Brönmark, Christer; Nilsson, P Anders; Skov, Christian; Hansson, Lars-Anders; Brodersen, Jakob

    2015-09-01

    1. Migration is a widespread phenomenon, with powerful ecological and evolutionary consequences. Morphological adaptations to reduce the energetic costs associated with migratory transport are commonly documented for migratory species. However, few studies have investigated whether variation in body morphology can be explained by variation in migratory strategy within a species. 2. We address this question in roach Rutilus rutilus, a partially migratory freshwater fish that migrates from lakes into streams during winter. We both compare body shape between populations that differ in migratory opportunity (open vs. closed lakes), and between individuals from a single population that vary in migratory propensity (migrants and residents from a partially migratory population). Following hydrodynamic theory, we posit that migrants should have a more shallow body depth, to reduce the costs associated with migrating into streams with higher flow conditions than the lakes the residents occupy all year round. 3. We find evidence both across and within populations to support our prediction, with individuals from open lakes and migrants from the partially migratory population having a more slender, shallow-bodied morphology than fish from closed lakes and all-year residents. 4. Our data suggest that a shallow body morphology is beneficial to migratory individuals and our study is one of the first to link migratory strategy and intraspecific variation in body shape. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

  7. Seeing shapes in seemingly random spatial patterns: Fractal analysis of Rorschach inkblots

    Science.gov (United States)

    Taylor, R. P.; Martin, T. P.; Montgomery, R. D.; Smith, J. H.; Micolich, A. P.; Boydston, C.; Scannell, B. C.; Fairbanks, M. S.; Spehar, B.

    2017-01-01

    Rorschach inkblots have had a striking impact on the worlds of art and science because of the remarkable variety of associations with recognizable and namable objects they induce. Originally adopted as a projective psychological tool to probe mental health, psychologists and artists have more recently interpreted the variety of induced images simply as a signature of the observers’ creativity. Here we analyze the relationship between the spatial scaling parameters of the inkblot patterns and the number of induced associations, and suggest that the perceived images are induced by the fractal characteristics of the blot edges. We discuss how this relationship explains the frequent observation of images in natural scenery. PMID:28196082

  8. Estimating the Spatial Distribution of Groundwater Age Using Synoptic Surveys of Environmental Tracers in Streams

    Science.gov (United States)

    Gardner, W. P.

    2017-12-01

    A model which simulates tracer concentration in surface water as a function the age distribution of groundwater discharge is used to characterize groundwater flow systems at a variety of spatial scales. We develop the theory behind the model and demonstrate its application in several groundwater systems of local to regional scale. A 1-D stream transport model, which includes: advection, dispersion, gas exchange, first-order decay and groundwater inflow is coupled a lumped parameter model that calculates the concentration of environmental tracers in discharging groundwater as a function of the groundwater residence time distribution. The lumped parameters, which describe the residence time distribution, are allowed to vary spatially, and multiple environmental tracers can be simulated. This model allows us to calculate the longitudinal profile of tracer concentration in streams as a function of the spatially variable groundwater age distribution. By fitting model results to observations of stream chemistry and discharge, we can then estimate the spatial distribution of groundwater age. The volume of groundwater discharge to streams can be estimated using a subset of environmental tracers, applied tracers, synoptic stream gauging or other methods, and the age of groundwater then estimated using the previously calculated groundwater discharge and observed environmental tracer concentrations. Synoptic surveys of SF6, CFC's, 3H and 222Rn, along with measured stream discharge are used to estimate the groundwater inflow distribution and mean age for regional scale surveys of the Berland River in west-central Alberta. We find that groundwater entering the Berland has observable age, and that the age estimated using our stream survey is of similar order to limited samples from groundwater wells in the region. Our results show that the stream can be used as an easily accessible location to constrain the regional scale spatial distribution of groundwater age.

  9. A measurement of global event shape distributions in the hadronic decays of the Z sup 0

    Energy Technology Data Exchange (ETDEWEB)

    Akrawy, M.Z.; Alexander, G.; Allison, J.; Allport, P.P.; Anderson, K.J.; Armitage, J.C.; Arnison, G.T.J.; Ashton, P.; Azuelos, G.; Baines, J.T.M.; Ball, A.H.; Banks, J.; Barker, G.J.; Barlow, R.J.; Batley, J.R.; Becker, J.; Behnke, T.; Bell, K.W.; Bella, G.; Bethke, S.; Biebel, O.; Binder, U.; Bloodworth, L.J.; Bock, P.; Breuker, H.; Brown, R.M.; Brun, R.; Buijs, A.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, D.G.; Chrin, J.T.M.; Cohen, I.; Collins, W.J.; Conboy, J.E.; Couch, M.; Coupland, M.; Cuffiani, M.; Dado, S.; Dallavalle, G.M.; Debu, P.; Deninno, M.M.; Dieckmann, A.; Dittmar, M.; Dixit, M.S.; Duchovni, E.; Duerdoth, I.P.; Dumas, D.; El Mamouni, H.; Elcombe, P.A.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Farthouat, P.; Fischer, H.M.; Fong, D.G.; French, M.T.; Fukunaga, C.; Gaidot, A.; Ganel, O.; Gary, J.W.; Gascon, J.; Geddes, N.I.; Gee, C.N.P.; Geich-Gimbel, C.; Gensler, S.W.; Gentit, F.X.; Giacomelli, G.; Gibson, V.; Gibs; OPAL Collaboration

    1990-08-01

    We present measurements of global event shape distributions in the hadronic decays of the Z{sup 0}. The data sample, corresponding to an integrated luminosity of about 1.3 pb{sup -1}, was collected with the OPAL detector at LEP. Most of the experimental distributions we present are unfolded for the finite acceptance and resolution of the OPAL detector. Through comparison with our unfolded data, we tune the parameter values of several Monte Carlo computer programs which simulate perturbative QCD and the hadronization of partons. Jetset version 7.2, Herwig version 3.4 and Ariadne version 3.1 all provide good descriptions of the experimental distributions. They in addition describe lower energy data with the parameter values adjusted at the Z{sup 0} energy. A complete second order matrix element Monte Carlo program with a modified perturbation scale is also compared to our 91 GeV data and its parameter values are adjusted. We obtained and unfolded value for the mean charged multiplicity of 21.28{plus minus}0.04{plus minus}0.84, where the first error is statistical and the second is systematic. (orig.).

  10. POPULATION STRUCTURE AND SPATIAL DISTRIBUTION OF Ceratozamia mexicana BRONGN. (ZAMIACEAE IN PRESERVED AND DISTURBED ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    Andrés Rivera-Fernández

    2012-11-01

    Full Text Available Vegetal populations are affected by biotic and abiotic factors that influence the regeneration processes. The aims of this study were to know the population structure of Ceratozamia mexicana under two contrasting conditions (conserved site and disturbed site, and to determine if the sexual structure, the population density and the spatial distribution of C. mexicana are modified by effect of disturbance. Eight plots of 25 m2 within each site (conserved and disturbed were used. The structure and spatial distribution of the sites were determined. Methods included analysis of variance, spatial distribution indexes, and climatic and edaphic factors determined by conventional methods for their comparison. The conserved site showed a demographic structure of an inverted "J", while the disturbed site varied slightly with more discontinuous distribution. Population density was 0.78 individuals/m2 in the conserved site and 0.26 individuals/m2 in the disturbed site. Spatial distribution for all development stages of the plant was random, with the exception of the seedling stage, which was aggregated. Results showed that perturbation decreases the density of plants and removes reproductive individuals, which threatens the persistence of the population.

  11. Spatial Control of Photoemitted Electron Beams using a Micro-Lens-Array Transverse-Shaping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [Northern Illinois U.; Qiang, G. [Tsinghua U., Beijing, Dept. Eng. Phys.; Ha, G. [POSTECH; Wisniewski, E. [Argonne (main); Piot, P. [NIU, DeKalb; Power, J. G. [Argonne (main); Gai, W. [Argonne (main)

    2017-07-24

    A common issue encountered in photoemission electron sources used in electron accelerators is the transverse inhomogeneity of the laser distribution resulting from the laser-amplification process and often use of frequency up conversion in nonlinear crystals. A inhomogeneous laser distribution on the photocathode produces charged beams with lower beam quality. In this paper, we explore the possible use of microlens arrays (fly-eye light condensers) to dramatically improve the transverse uniformity of the drive laser pulse on UV photocathodes. We also demonstrate the use of such microlens arrays to generate transversely-modulated electron beams and present a possible application to diagnose the properties of a magnetized beam.

  12. Particle size-shape distributions: the general spheroid problem. I. Mathematical model.

    Science.gov (United States)

    Orive, L M

    1976-08-01

    The development of stereological methods for the study of dilute phases of particles, voids or organelles embedded in a matrix, from measurements made on plane or linear intercepts through the aggregate, has deserved a great deal of effort. With almost no exception, the problem of describing the particulate phase is reduced to that of identifying the statistical distribution--histogram in practice--of a relevant size parameter, with the previous assumption that the particles are modelled by geometrical objects of a constant shape (e.g. spheres). Therefore, particles exhibiting a random variation about a given type of shape as well as a random variation in size, escape previous analyses. Such is the case of unequiaxed particles modelled by triaxial ellipsoids of variable size and eccentricity parameters. It has been conjectured (Moran, 1972) that this problem is indetermined in its generally (i.e. the elliptical sections do not furnish a sufficient information which permits a complete description of the ellipsoids). A proof of this conjecture is given in the Appendix. When the ellipsoids are biaxial (spheroids) and of the same type (prolate or oblate), the problem is identifiable. Previous attempts to solve it assume statistical independence between size and shape. A complete, theoretical solution of the spheroids problem--with the independence condition relaxed--is presented. A number of exact relationships--some of them of a striking simplicity--linking particle properties (e.g. mean-mean caliper length, mean axial ratio, correlation coefficient between principal diameters, etc.) on the one hand, with the major and minor dimensions of the ellipses of section on the other, emerge, and natural, consistent estimators of the mentioned properties are made easily accessible for practical computation. Finally, the scope and limitations of the mathematical model are discussed.

  13. Non-uniform plasma distribution in dc magnetron sputtering: origin, shape and structuring of spokes

    Science.gov (United States)

    Panjan, Matjaž; Loquai, Simon; Ewa Klemberg-Sapieha, Jolanta; Martinu, Ludvik

    2015-12-01

    Non-homogeneous plasma distribution in the form of organized patterns called spokes was first observed in high power impulse magnetron sputtering (HiPIMS). In the present work we investigate the spoke phenomenon in non-pulsed low-current dc magnetron sputtering (DCMS). Using a high-speed camera the spokes were systematically studied with respect to discharge current, pressure, target material and magnetic field strength. Increase in the discharge current and/or gas pressure resulted in the sequential formation of two, then three and more spokes. The observed patterns were reproducible for the same discharge conditions. Spokes at low currents and pressures formed an elongated arrowhead-like shape and were commonly arranged in symmetrical patterns. Similar spoke patterns were observed for different target materials. When using a magnetron with a weaker magnetic field, spokes had an indistinct and diffuse shape, whereas in stronger magnetic fields spokes exhibited an arrowhead-like shape. The properties of spokes are discussed in relation to the azimuthally dependent electron-argon interactions. It is suggested that a single spoke is formed due to local gas breakdown and subsequent electron drift in the azimuthal direction. The spoke is self-sustained by electrons drifting in complex electric and magnetic fields that cause and govern azimuthally dependent processes: ionization, sputtering, and secondary electron emission. In this view plasma evolves from a single spoke into different patterns when discharge conditions are changed either by the discharge current, pressure or magnetic field strength. The azimuthal length of the spoke is associated with the electron-Ar collision frequency which increases with pressure and results in shortening of spoke until an additional spoke forms at a particular threshold pressure. It is proposed that the formation of additional spokes at higher pressures and discharge currents is, in part, related to the increased transport of

  14. Transient hepatic attenuation difference (THAD) in patients without neoplasm. Frequency, shape, distribution, and causes

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, Michio; Furukawa, Akira; Murata, Kiyoshi; Morita, Rikushi [Shiga Univ. of Medical Science, Otsu (Japan)

    1999-03-01

    Transient hepatic attenuation difference (THAD) is a valuable finding in detecting hypervascular lesions. However, similar findings are also observed in patients even without known hepatic diseases. We elucidate the characteristic findings and the causes of THAD in patients without hepatic neoplasm in this article. Dual-phased contrast-enhanced CT studies performed in 450 patients were reviewed, and THAD was observed in 42 (9.3%). THAD was linear or wedge-shaped and was seen contiguous to the liver surface with a relatively obscure margin in 40 of the 42 cases. The most common cause of THAD was chronic cholecystitis followed by previous biliary surgery. THAD was also seen in 30 patients with no hepatic diseases in whom it had a tendency to locate around the gallbladder fossa or in the periphery of the liver particularly in the left lobe. The knowledge of the prevalence, shape, distribution and causes of THAD is essential for the evaluation of contrast-enhanced CT images obtained during the arterial phase. (author)

  15. Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films.

    Science.gov (United States)

    Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P

    2018-04-04

    We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

  16. Preliminary Assessment of Optimal Longitudinal-Mode Control for Drag Reduction through Distributed Aeroelastic Shaping

    Science.gov (United States)

    Ippolito, Corey; Nguyen, Nhan; Lohn, Jason; Dolan, John

    2014-01-01

    The emergence of advanced lightweight materials is resulting in a new generation of lighter, flexible, more-efficient airframes that are enabling concepts for active aeroelastic wing-shape control to achieve greater flight efficiency and increased safety margins. These elastically shaped aircraft concepts require non-traditional methods for large-scale multi-objective flight control that simultaneously seek to gain aerodynamic efficiency in terms of drag reduction while performing traditional command-tracking tasks as part of a complete guidance and navigation solution. This paper presents results from a preliminary study of a notional multi-objective control law for an aeroelastic flexible-wing aircraft controlled through distributed continuous leading and trailing edge control surface actuators. This preliminary study develops and analyzes a multi-objective control law derived from optimal linear quadratic methods on a longitudinal vehicle dynamics model with coupled aeroelastic dynamics. The controller tracks commanded attack-angle while minimizing drag and controlling wing twist and bend. This paper presents an overview of the elastic aircraft concept, outlines the coupled vehicle model, presents the preliminary control law formulation and implementation, presents results from simulation, provides analysis, and concludes by identifying possible future areas for research

  17. Status of the ITER full-tungsten divertor shaping and heat load distribution analysis

    International Nuclear Information System (INIS)

    Carpentier-Chouchana, S; Hirai, T; Escourbiac, F; Durocher, A; Fedosov, A; Ferrand, L; Kocan, M; Kukushkin, A S; Jokinen, T; Komarov, V; Lehnen, M; Merola, M; Mitteau, R; Pitts, R A; Sugihara, M; Firdaouss, M; Stangeby, P C

    2014-01-01

    In September 2011, the ITER Organization (IO) proposed to begin operation with a full-tungsten (W) armoured divertor, with the objective of taking a decision on the final target material (carbon fibre composite or W) by the end of 2013. This period of 2 years would enable the development of a full-W divertor design compatible with nuclear operations, the investigation of further several physics R and D aspects associated with the use of W targets and the completion of technology qualification. Beginning with a brief overview of the reference heat load specifications which have been defined for the full-W engineering activity, this paper will report on the current status of the ITER divertor shaping and will summarize the results of related three-dimensional heat load distribution analysis performed as part of the design validation. (paper)

  18. Shape up or ship out: Migratory behaviour predicts morphology across spatial scale in a freshwater fish

    DEFF Research Database (Denmark)

    Chapman, B.B.; Hulthén, K.; Brönmark, C.

    2015-01-01

    Migration is a widespread phenomenon, with powerful ecological and evolutionary consequences. Morphological adaptations to reduce the energetic costs associated with migratory transport are commonly documented for migratory species. However, few studies have investigated whether variation in body...... morphology can be explained by variation in migratory strategy within a species. We address this question in roach Rutilus rutilus, a partially migratory freshwater fish that migrates from lakes into streams during winter. We both compare body shape between populations that differ in migratory opportunity...... with migrating into streams with higher flow conditions than the lakes the residents occupy all year round. We find evidence both across and within populations to support our prediction, with individuals from open lakes and migrants from the partially migratory population having a more slender, shallow...

  19. Assessment of Homodyned K Distribution Modeling Ultrasonic Speckles from Scatterers with Varying Spatial Organizations

    Directory of Open Access Journals (Sweden)

    Xiao Hu

    2017-01-01

    Full Text Available Objective. This paper presents an assessment of physical meanings of parameter and goodness of fit for homodyned K (HK distribution modeling ultrasonic speckles from scatterer distributions with wide-varying spatial organizations. Methods. A set of 3D scatterer phantoms based on gamma distributions is built to be implemented from the clustered to random to uniform scatterer distributions continuously. The model parameters are obtained by maximum likelihood estimation (MLE from statistical histograms of the ultrasonic envelope data and then compared with those by the optimally fitting models chosen from three single distributions. Results show that the parameters of the HK distribution still present their respective physical meanings of independent contributions in the scatterer distributions. Moreover, the HK distribution presents better goodness of fit with a maximum relative MLE difference of 6.23% for random or clustered scatterers with a well-organized periodic structure. Experiments based on ultrasonic envelope data from common carotid arterial B-mode images of human subjects validate the modeling performance of HK distribution. Conclusion. We conclude that the HK model for ultrasonic speckles is a better choice for characterizing tissue with a wide variety of spatial organizations, especially the emphasis on the goodness of fit for the tissue in practical applications.

  20. Spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene crystallized under combined thermal and flow fields.

    Science.gov (United States)

    Wang, Yan; Pan, Ji-Lin; Mao, Yimin; Li, Zhong-Ming; Li, Liangbin; Hsiao, Benjamin S

    2010-05-27

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of gamma-crystal (f(gamma)) with respect to alpha-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f(gamma) increased monotonously from skin to core in CIM samples, whereas the corresponding f(gamma) increased nonmonotonically in OSIM samples. The spatial distribution of gamma-crystal in OSIM samples can be explained by the epitaxial arrangement between gamma- and alpha-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of alpha-crystal provide secondary nucleation sites for daughter lamellae of alpha-crystal and gamma-crystal, and the different content of parent lamellae results in varying amounts of gamma-crystal. In OSIM samples, the smallest parent-daughter ratio ([R]) = 1.38) in the core region led to the lowest fraction of gamma-crystal (0.57), but relatively higher gamma-crystal content (0.69) at 600 and 1200 mum depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of gamma-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The observed double-melting peaks

  1. Spatial Distribution of -Crystals in Metallocene-Made Isotactic Polypropylene Crystallized under Combined Thermal and Flow Fields

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Pan, J; Mao, Y; Li, Z; Li, L; Hsiao, B

    2010-01-01

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of {gamma}-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of {gamma}-crystal (f{gamma}) with respect to {alpha}-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f{gamma} increased monotonously from skin to core in CIM samples, whereas the corresponding f{gamma} increased nonmonotonically in OSIM samples. The spatial distribution of {gamma}-crystal in OSIM samples can be explained by the epitaxial arrangement between {gamma}- and {alpha}-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of {alpha}-crystal provide secondary nucleation sites for daughter lamellae of {alpha}-crystal and {gamma}-crystal, and the different content of parent lamellae results in varying amounts of {gamma}-crystal. In OSIM samples, the smallest parent-daughter ratio ([R] = 1.38) in the core region led to the lowest fraction of {gamma}-crystal (0.57), but relatively higher {gamma}-crystal content (0.69) at 600 and 1200 {micro}m depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of {gamma}-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The

  2. Does Vertebroplasty Affect Radiation Dose Distribution?: Comparison of Spatial Dose Distributions in a Cement-Injected Vertebra as Calculated by Treatment Planning System and Actual Spatial Dose Distribution

    International Nuclear Information System (INIS)

    Komemushi, A.; Tanigawa, N.; Kariya, Sh.; Yagi, R.; Nakatani, M.; Suzuki, S.; Sano, A.; Ikeda, K.; Utsunomiya, K.; Harima, Y.; Sawada, S.

    2012-01-01

    Purpose. To assess differences in dose distribution of a vertebral body injected with bone cement as calculated by radiation treatment planning system (RTPS) and actual dose distribution. Methods. We prepared two water-equivalent phantoms with cement, and the other two phantoms without cement. The bulk density of the bone cement was imported into RTPS to reduce error from high CT values. A dose distribution map for the phantoms with and without cement was calculated using RTPS with clinical setting and with the bulk density importing. Actual dose distribution was measured by the film density. Dose distribution as calculated by RTPS was compared to the dose distribution measured by the film dosimetry. Results. For the phantom with cement, dose distribution was distorted for the areas corresponding to inside the cement and on the ventral side of the cement. However, dose distribution based on film dosimetry was undistorted behind the cement and dose increases were seen inside cement and around the cement. With the equivalent phantom with bone cement, differences were seen between dose distribution calculated by RTPS and that measured by the film dosimetry. Conclusion. The dose distribution of an area containing bone cement calculated using RTPS differs from actual dose distribution

  3. Hydrodynamic Characterization of Substrate Gradients in a Pilot Scale Fermenter Using CFD and Spatially Distributed Sensors

    DEFF Research Database (Denmark)

    Bach, Christian; Albæk, Mads Orla; Krühne, Ulrich

    The prediction and understanding of mixing and oxygen mass transfer in fermenters and bioreactors is useful for bioprocess improvement as these dynamics govern production rates of the biotransformation. In particular heterogeneities occurring under process conditions is of interest as such gradie...... by catalase to illustrate and validate how substrate is distributed throughout the vessel by combining CFD and experimental data collected with spatially distributed sensors....

  4. High spatial and temporal resolution interrogation of fully distributed chirped fiber Bragg grating sensors

    OpenAIRE

    Ahmad, Eamonn J.; Wang, Chao; Feng, Dejun; Yan, Zhijun; Zhang, Lin

    2017-01-01

    A novel interrogation technique for fully distributed linearly chirped fiber Bragg grating (LCFBG) strain sensors with simultaneous high temporal and spatial resolution based on optical time-stretch frequency-domain reflectometry (OTS-FDR) is proposed and experimentally demonstrated. LCFBGs is a promising candidate for fully distributed sensors thanks to its longer grating length and broader reflection bandwidth compared to normal uniform FBGs. In the proposed system, two identical LCFBGs are...

  5. Spatial distribution of luminous X-ray binaries in spiral galaxies

    OpenAIRE

    Zuo, Zhao-yu; Li, Xiang-dong; Liu, Xi-wei

    2008-01-01

    We have modelled the spatial distribution of luminous X-ray binaries (XRBs) in spiral galaxies that are like the Milky Way using an evolutionary population synthesis code. In agreement with previous theoretical expectations and observations, we find that both high- and low-mass XRBs show clear concentrations towards the galactic plane and bulge.We also compare XRB distributions under the galactic potential with a dark matter halo and the modified Newtonian dynamics potential, and we suggest t...

  6. Nuclear distributions of NUP62 and NUP214 suggest architectural diversity and spatial patterning among nuclear pore complexes.

    Directory of Open Access Journals (Sweden)

    Yayoi Kinoshita

    Full Text Available The shape of nuclei in many adherent cultured cells approximates an oblate ellipsoid, with contralateral flattened surfaces facing the culture plate or the medium. Observations of cultured cell nuclei from orthogonal perspectives revealed that nucleoporin p62 (NUP62 and nucleoporin 214 (NUP214 are differentially distributed between nuclear pore complexes on the flattened surfaces and peripheral rim of the nucleus. High resolution stimulated emission depletion (STED immunofluorescence microscopy resolved individual NPCs, and suggested both heterogeneity and microheterogeneity in NUP62 and NUP214 immunolabeling among in NPC populations. Similar to nuclear domains and interphase chromosome territories, architectural diversity and spatial patterning of NPCs may be an intrinsic property of the nucleus that is linked to the functions and organization of underlying chromatin.

  7. Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

    Science.gov (United States)

    Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

    2015-11-02

    Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions.

  8. A Permutation-Randomization Approach to Test the Spatial Distribution of Plant Diseases.

    Science.gov (United States)

    Lione, G; Gonthier, P

    2016-01-01

    The analysis of the spatial distribution of plant diseases requires the availability of trustworthy geostatistical methods. The mean distance tests (MDT) are here proposed as a series of permutation and randomization tests to assess the spatial distribution of plant diseases when the variable of phytopathological interest is categorical. A user-friendly software to perform the tests is provided. Estimates of power and type I error, obtained with Monte Carlo simulations, showed the reliability of the MDT (power > 0.80; type I error pathogens causing root rot on conifers was successfully performed by verifying the consistency between the MDT responses and previously published data. An application of the MDT was carried out to analyze the relation between the plantation density and the distribution of the infection of Gnomoniopsis castanea, an emerging fungal pathogen causing nut rot on sweet chestnut. Trees carrying nuts infected by the pathogen were randomly distributed in areas with different plantation densities, suggesting that the distribution of G. castanea was not related to the plantation density. The MDT could be used to analyze the spatial distribution of plant diseases both in agricultural and natural ecosystems.

  9. mocca code for star cluster simulations - VI. Bimodal spatial distribution of blue stragglers

    Science.gov (United States)

    Hypki, Arkadiusz; Giersz, Mirek

    2017-11-01

    The paper presents an analysis of formation mechanism and properties of spatial distributions of blue stragglers in evolving globular clusters, based on numerical simulations done with the mocca code. First, there are presented N-body and mocca simulations which try to reproduce the simulations presented by Ferraro et al. (2012). Then, we show the agreement between N-body and the mocca code. Finally, we discuss the formation process of the bimodal distribution. We report that we could not reproduce simulations from Ferraro et al. (2012). Moreover, we show that the so-called bimodal spatial distribution of blue stragglers is a very transient feature. It is formed for one snapshot in time and it can easily vanish in the next one. Moreover, we show that the radius of avoidance proposed by Ferraro et al. (2012) goes out of sync with the apparent minimum of the bimodal distribution after about two half-mass relaxation times (without finding out what is the reason for that). This finding creates a real challenge for the dynamical clock, which uses this radius to determine the dynamical age of globular clusters. Additionally, the paper discusses a few important problems concerning the apparent visibilities of the bimodal distributions, which have to be taken into account while studying the spatial distributions of blue stragglers.

  10. Methods and apparatus for determining the spatial distribution of a radioactive material

    International Nuclear Information System (INIS)

    Todd, R.W.

    1975-01-01

    The spatial distribution of a radioactive material is determined by locating the positions of and energy losses resulting from Compton interactions which occur in a detector as a result of gamma photons emitted by the radioactive material, which may, for example, have been administered to a patient for medical diagnostic investigation. (auth)

  11. Tachistoscopic Treatment of Dyslexia Changes the Distribution of Visual-Spatial Attention

    Science.gov (United States)

    Lorusso, M.L.; Facoetti, A.; Toraldo, A.; Molteni, M.

    2005-01-01

    Twelve children with developmental dyslexia underwent a four-month treatment with tachistoscopic presentation of words, according to Bakker's methodology. One group received standard lateral presentation of words on a PC screen, while the other group received the same stimuli in random lateral position. The spatial distribution of visual attention…

  12. The spatial distribution of coastal fish assemblage in Côte d'Ivoire's ...

    African Journals Online (AJOL)

    The spatial distribution of coastal fish assemblage in Côte d'Ivoire's Exclusive Economic Zone (EEZ), West Africa. Soumaïla Sylla, Kouadio Fréderic Kouakou, Christian Bernard Tia, Stanislas Silvain Yao, Boua Célestin Atse ...

  13. PECULIARITIES OF THE SPATIAL DISTRIBUTION OF THE NOCTUIDAE (LEPIDOPTERA, NOCTUIDAE OF THE ISLAND OF CHECHEN

    Directory of Open Access Journals (Sweden)

    G. M. Abdurakhmanov

    2012-01-01

    Full Text Available The paper presents the species composition of the noctuidae (Lepidoptera, Noctuidae of the island of Chechen of the North-West Caspian sea, their spatial distribution,  dissemination  and analysis of the most common and indigenous species.

  14. Modelling the effect of intersections in linear habitat on spatial distribution and local population density

    NARCIS (Netherlands)

    Langevelde, van F.; Grashof-Bokdam, C.J.

    2011-01-01

    Many species in human-dominated landscapes find their habitat in linear elements, such as road verges, hedgerows and ditches. Local concentrations of species have been observed in the intersections of linear elements, but their spatial distribution and local population density in this linear habitat

  15. Winter spatial distribution of threatened acridivorous avian predators : Implications for their conservation in a changing landscape

    NARCIS (Netherlands)

    Augiron, Steve; Gangloff, Benoit; Brodier, Salomon; Chevreux, Fabrice; Blanc, Jean-Francois; Pilard, Philippe; Coly, Adrien; Sonko, Abba; Schlaich, Almut; Bretagnolle, Vincent; Villers, Alexandre

    The Montagu's Harrier (MH) and the Lesser Kestrel (LK) are two threatened raptors overwintering in the Sahel. To ensure their conservation, it is essential to gain better knowledge on their winter ecology in order to predict their spatial distribution and estimate their respective population sizes.

  16. Spatial distribution of seeds and seedlings of two tropical tree species: Is there correspondence between patterns?

    International Nuclear Information System (INIS)

    Parrado Rosselli, Angela

    2007-01-01

    The spatial patterns of seed and seedling distribution relative to parent trees (seed and seedling shadow, respectively) were studied for Dacryodes chimantensis (Burseraceae) and Brosimum utile (Moraceae), two common tree species of terra firme forests of Colombian Amazonia. The general objective was to assess whether the patterns imposed by seed dispersal change or persist in subsequent life stages occurring during the transition from seeds/saplings to adult stages. Seed and seedling shadows on the ground were characterized for each tree species along four 50-m radial transects from the base of the parent tree. Causes of seed and seedling predation as a function of distance to the parent tree were determined, as well as the spatial consistency between life stages. Results showed that seed density of both Dacryodes and Brosimum declined leptokurtically with distance, and it was skewed towards the parent tree. However, seed density was more skewed and leptokurtic in Dacryodes than in Brosimum. The overall trend was maintained in the seedling stage of both species and was positively correlated with the distribution patterns of seeds. Seed and seedling predation were positively correlated with density and negatively correlated with the distance from the parent tree. Factors that could be generating the high consistency between the spatial patterns of seed and seedling distribution are discussed, as well as its implications in the population structure of both species and the debate on the factors that influence the spatial distribution of plant species in tropical rain forests.

  17. Spatial distribution of non-clinical Rift Valley fever viral activity in ...

    African Journals Online (AJOL)

    Rift Valley fever (RVF) is an acute zoonotic viral disease of domestic ruminants in mainland Africa and Madagascar. The disease may exist in non-clinical form in apparently health animals. This study was designed to investigate the existence and spatial distribution of non-clinical form of RVF virus (RVFV) activity in wild and ...

  18. Spatial distribution of bacteria associated with the marine sponge Tethya californiana

    NARCIS (Netherlands)

    Sipkema, D.; Blanch, H.W.

    2010-01-01

    Microbial diversity and spatial distribution of the diversity within tissue of the marine sponge Tethya californiana was analyzed based on 16S rRNA gene sequences. One candidate division and nine bacterial phyla were detected, including members of all five subdivisions of Proteobacteria. Moreover,

  19. Unequal access to higher education in the Czech Republic: the role of spatial distribution of universities

    Czech Academy of Sciences Publication Activity Database

    Franta, Michal; Guzi, Martin

    -, č. 350 (2008), s. 1-56 ISSN 1211-3298 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : access to tertiary education * human capital * spatial distribution Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp350.pdf

  20. Modelling the spatial distribution of SO2 and NO(x) emissions in Ireland

    NARCIS (Netherlands)

    Kluizenaar, Y.de; Aherne, J.; Farrell, E.P.

    2001-01-01

    The spatial distributions of sulphur dioxide (SO2) and nitrogen oxides (NO(x)) emissions are essential inputs to models of atmospheric transport and deposition. Information of this type is required for international negotiations on emission reduction through the critical load approach.

  1. Spatial distribution of urban heat island in Hangzhou and its mitigation countermeasures

    DEFF Research Database (Denmark)

    Wang, W.-W.; Li, G.-L.; Xue, J.

    2009-01-01

    Taking Hangzhou City in summer as a case, the thermal infrared remote sensing image (Landsat 5 TM) was used to extract and inverse the surface land cover types and surface temperature of Hangzhou City. The spatial distribution characteristics of urban heat island was analyzed in the city-scale th...

  2. Population dynamics and spatial distribution of Griffon Vultures (Gyps fulvus) Portugal

    NARCIS (Netherlands)

    Beest, van F.M.; Bremer, van den L.; Boer, de W.F.; Heitkonig, I.M.A.; Monteiro, A.E.

    2008-01-01

    The global decrease of vulture populations has been attributed to several factors, such as food availability, poisoning, human disturbance, or habitat suitability. We studied the effect of factors that vary both spatially and temporally on the nest site distribution of the Griffon Vulture Gyps

  3. Effect of Action Video Games on the Spatial Distribution of Visuospatial Attention

    Science.gov (United States)

    Green, C. Shawn; Bavelier, Daphne

    2006-01-01

    The authors investigated the effect of action gaming on the spatial distribution of attention. The authors used the flanker compatibility effect to separately assess center and peripheral attentional resources in gamers versus nongamers. Gamers exhibited an enhancement in attentional resources compared with nongamers, not only in the periphery but…

  4. Predictors, spatial distribution, and occurrence of woody invasive plants in subtropical urban ecosystems

    Science.gov (United States)

    Christina L. Staudhammer; Francisco J. Escobedo; Nathan Holt; Linda J. Young; Thomas J. Brandeis; Wayne Zipperer; Other

    2015-01-01

    We examined the spatial distribution, occurrence, and socioecological predictors of woody invasive plants (WIP) in two subtropical, coastal urban ecosystems: San Juan, Puerto Rico and Miami-Dade, United States. These two cities have similar climates and ecosystems typical of subtropical regions but differ in socioeconomics, topography, and urbanization processes. Using...

  5. The influence of row width and seed spacing on uniformity of plant spatial distributions

    DEFF Research Database (Denmark)

    Griepentrog, Hans W.; Olsen, Jannie Maj; Weiner, Jacob

    2009-01-01

    width and evenness of spacing within rows influences two-dimensional spatial quality. The results can be used to define new requirements for improved seeding technologies to achieve higher benefits in sustainable crop production systems. In general it can be concluded that more even plant distributions...... are expected to result in a better crop plant performance....

  6. Concentration, spatial and size distribution of airborne aerobic mesophilic bacteria in broiler farms

    NARCIS (Netherlands)

    Adell, E.; Moset, V.; Yang Zhao, Yang; Cerisuelo, A.; Cambra-Lopez, M.

    2011-01-01

    In livestock houses, particulate matter (PM) and airborne microorganism are two of the most relevant air pollutants. Particulate matter may carry microorganisms, the inhalation of which can cause detrimental health effects. The aim of this study was to study the spatial distribution of airborne

  7. Characterization of the spatial distribution of farming systems in the Kenyan Highlands

    NARCIS (Netherlands)

    Steeg, J.A.; Verburg, P.H.; Baltenweck, I.; Staal, S.J.

    2010-01-01

    Land cover change maps are not sufficient to identify subtle changes in land use and farming systems. This paper describes a method that is developed to identify the spatial distribution of farming system types without the need to extensively map all farming systems across a large region. Moreover,

  8. Abiotic and biotic controls on local spatial distribution and performance of Boechera stricta

    Directory of Open Access Journals (Sweden)

    KUSUM J NAITHANI

    2014-07-01

    Full Text Available This study investigates the relative influence of biotic and abiotic factors on community dynamics using an integrated approach and highlights the influence of space on genotypic and phenotypic traits in plant community structure. We examined the relative influence of topography, environment, spatial distance, and intra- and interspecific interactions on spatial distribution and performance of Boechera stricta (rockcress, a close perennial relative of model plant Arabidopsis. First, using Bayesian kriging, we mapped the topography and environmental gradients and explored the spatial distribution of naturally occurring rockcress plants and two neighbors, Taraxacum officinale (dandelion and Solidago missouriensis (goldenrod found in close proximity within a typical diverse meadow community across topographic and environmental gradients. We then evaluated direct and indirect relationships among variables using Mantel path analysis and developed a network displaying abiotic and biotic interactions in this community. We found significant spatial autocorrelation among rockcress individuals, either because of common microhabitats as displayed by high density of individuals at lower elevation and high soil moisture area, or limited dispersal as shown by significant spatial autocorrelation of naturally occurring inbred lines, or a combination of both. Goldenrod and dandelion density around rockcress does not show any direct relationship with rockcress fecundity, possibly due to spatial segregation of resources. However, dandelion density around rockcress shows an indirect negative influence on rockcress fecundity via herbivory, indicating interspecific competition. Overall, we suggest that common microhabitat preference and limited dispersal are the main drivers for spatial distribution. However, intra-specific interactions and insect herbivory are the main drivers of rockcress performance in the meadow community.

  9. Spatial Distribution of Adults of Triozoida limbata (Enderlein) (Hemiptera: Triozidae) in Guava Plants.

    Science.gov (United States)

    Marcelino, M C S; Barbosa, J C

    2016-04-01

    The psyllid Triozoida limbata (Enderlein) (Hemiptera: Triozidae) is a major pest in guava, feeding primarily on new shoots. Despite its importance, there are no studies on the spatial distribution of T. limbata on guava. Such studies are needed to establish sequential sampling plans for decision making in pest control. Thus, an experiment was carried out in a 9-year-old commercial guava orchard divided into 100 sampling units or plots. Double-sided yellow sticky traps were placed on one plant per plot (sample unit) to capture and monitor T. limbata adults from April 2011 to May 2012. To determine the insect distribution in the area, we calculated the variance-to-mean ratio index (I), the Morisita index (I δ ), Green's coefficient (Cx), and the k exponent of the negative binomial distribution. Most of the samples showed that the adults had a moderate to highly aggregated distribution. Statistical models were also used to study the pest spatial distribution by fitting the number of adults captured to the Poisson and negative binomial distributions. The negative binomial distribution model best fitted the data of the number of adult psyllids captured by the traps, which is consistent with an aggregated distribution.

  10. Interacting Social and Environmental Predictors for the Spatial Distribution of Conservation Lands

    Science.gov (United States)

    Baldwin, Robert F.; Leonard, Paul B.

    2015-01-01

    Conservation decisions should be evaluated for how they meet conservation goals at multiple spatial extents. Conservation easements are land use decisions resulting from a combination of social and environmental conditions. An emerging area of research is the evaluation of spatial distribution of easements and their spatial correlates. We tested the relative influence of interacting social and environmental variables on the spatial distribution of conservation easements by ownership category and conservation status. For the Appalachian region of the United States, an area with a long history of human occupation and complex land uses including public-private conservation, we found that settlement, economic, topographic, and environmental data associated with spatial distribution of easements (N = 4813). Compared to random locations, easements were more likely to be found in lower elevations, in areas of greater agricultural productivity, farther from public protected areas, and nearer other human features. Analysis of ownership and conservation status revealed sources of variation, with important differences between local and state government ownerships relative to non-governmental organizations (NGOs), and among U.S. Geological Survey (USGS) GAP program status levels. NGOs were more likely to have easements nearer protected areas, and higher conservation status, while local governments held easements closer to settlement, and on lands of greater agricultural potential. Logistic interactions revealed environmental variables having effects modified by social correlates, and the strongest predictors overall were social (distance to urban area, median household income, housing density, distance to land trust office). Spatial distribution of conservation lands may be affected by geographic area of influence of conservation groups, suggesting that multi-scale conservation planning strategies may be necessary to satisfy local and regional needs for reserve networks. Our

  11. A comparative study of spatially clustered distribution of jumbo flying squid ( Dosidicus gigas) offshore Peru

    Science.gov (United States)

    Feng, Yongjiu; Cui, Li; Chen, Xinjun; Liu, Yu

    2017-06-01

    We examined spatially clustered distribution of jumbo flying squid ( Dosidicus gigas) in the offshore waters of Peru bounded by 78°-86°W and 8°-20°S under 0.5°×0.5° fishing grid. The study is based on the catch-per-unit-effort (CPUE) and fishing effort from Chinese mainland squid jigging fleet in 2003-2004 and 2006-2013. The data for all years as well as the eight years (excluding El Niño events) were studied to examine the effect of climate variation on the spatial distribution of D. gigas. Five spatial clusters reflecting the spatial distribution were computed using K-means and Getis-Ord Gi* for a detailed comparative study. Our results showed that clusters identified by the two methods were quite different in terms of their spatial patterns, and K-means was not as accurate as Getis-Ord Gi*, as inferred from the agreement degree and receiver operating characteristic. There were more areas of hot and cold spots in years without the impact of El Niño, suggesting that such large-scale climate variations could reduce the clustering level of D. gigas. The catches also showed that warm El Niño conditions and high water temperature were less favorable for D. gigas offshore Peru. The results suggested that the use of K-means is preferable if the aim is to discover the spatial distribution of each sub-region (cluster) of the study area, while Getis-Ord Gi* is preferable if the aim is to identify statistically significant hot spots that may indicate the central fishing ground.

  12. Identifying biotic interactions which drive the spatial distribution of a mosquito community.

    Science.gov (United States)

    Golding, Nick; Nunn, Miles A; Purse, Bethan V

    2015-07-14

    Spatial variation in the risk of many mosquito-borne pathogens is strongly influenced by the distribution of communities of suitable vector mosquitoes. The spatial distributions of such communities have been linked to the abiotic habitat requirements of each constituent mosquito species, but the biotic interactions between mosquitoes and other species are less well understood. Determining which fauna restrict the presence and abundance of key mosquito species in vector communities may identify species which could be employed as natural biological control agents. Whilst biotic interactions have been studied in the laboratory, a lack of appropriate statistical methods has prohibited the identification of key interactions which influence mosquito distributions in the field. Joint species distribution models (JSDMs) have recently been developed to identify biotic interactions influencing the distributions of species from empirical data. We apply a JSDM to field data on the spatial distribution of mosquitoes in a UK wetland to identify both abiotic factors and biotic interactions driving the composition of the community. As expected, mosquito larval distributions in this wetland habitat are strongly driven by environmental covariates including water depth, temperature and oxidation-reduction potential. By factoring out these environmental variables, we are able to identify species (ditch shrimp of the genus Palaemonetes and fish) as predators which appear to restrict mosquito distributions. JSDMs offer vector ecologists a way to identify potentially important biotic interactions influencing the distributions of disease vectors from widely available field data. This information is crucial to understand the likely effects of habitat management for vector control and to identify species with the potential for use in biological control programmes. We provide an R package BayesComm to enable the wider application of these models.

  13. AIDEN: A Density Conscious Artificial Immune System for Automatic Discovery of Arbitrary Shape Clusters in Spatial Patterns

    Directory of Open Access Journals (Sweden)

    Vishwambhar Pathak

    2012-11-01

    Full Text Available Recent efforts in modeling of dynamics of the natural immune cells leading to artificial immune systems (AIS have ignited contemporary research interest in finding out its analogies to real world problems. The AIS models have been vastly exploited to develop dependable robust
    solutions to clustering. Most of the traditional clustering methods bear limitations in their capability to detect clusters of arbitrary shapes in a fully unsupervised manner. In this paper the recognition and communication dynamics of T Cell Receptors, the recognizing elements in innate immune
    system, has been modeled with a kernel density estimation method. The model has been shown to successfully discover non spherical clusters in spatial patterns. Modeling the cohesion of the antibodies and pathogens with ‘local influence’ measure inducts comprehensive extension of the
    antibody representation ball (ARB, which in turn corresponds to controlled expansion of clusters and prevents overfitting.

  14. The painter from Sinaloa: artistic analysis of a case of spatial agnosia and neglect of visual shapes.

    Science.gov (United States)

    Orjuela-Rojas, Juan Manuel; Sosa-Ortiz, Ana Luisa; Díaz-Victoria, Ana Ruth; Marrufo Melendez, Oscar René; Leyva Townsend, Nicolás

    Paintings produced spontaneously by patients with neurological lesions represent a fascinating opportunity to analyze some aspects of the underlying disease and involved brain mechanisms. Many cases of artists who have suffered spatial neglect following a neurological disease have been reported in the literature. However, only a few studies evaluating the different subtypes of graphic neglect and aspects related to the construction of perspective (three dimensionality) in works of art have been published. In the present article, we present the case of an artist who, after resection of a central neurocytoma that affected the right thalamo-parietal connections, suffered an impairment of the ability to create perspective in his paintings and involuntary omission of only shapes in the left side of his paintings, although colors and contours were preserved.

  15. Spatial Burnout in Water Reactors with Nonuniform Startup Distributions of Uranium and Boron

    Science.gov (United States)

    Fox, Thomas A.; Bogart, Donald

    1955-01-01

    Spatial burnout calculations have been made of two types of water moderated cylindrical reactor using boron as a burnable poison to increase reactor life. Specific reactors studied were a version of the Submarine Advanced Reactor (sAR) and a supercritical water reactor (SCW) . Burnout characteristics such as reactivity excursion, neutron-flux and heat-generation distributions, and uranium and boron distributions have been determined for core lives corresponding to a burnup of approximately 7 kilograms of fully enriched uranium. All reactivity calculations have been based on the actual nonuniform distribution of absorbers existing during intervals of core life. Spatial burnout of uranium and boron and spatial build-up of fission products and equilibrium xenon have been- considered. Calculations were performed on the NACA nuclear reactor simulator using two-group diff'usion theory. The following reactor burnout characteristics have been demonstrated: 1. A significantly lower excursion in reactivity during core life may be obtained by nonuniform rather than uniform startup distribution of uranium. Results for SCW with uranium distributed to provide constant radial heat generation and a core life corresponding to a uranium burnup of 7 kilograms indicated a maximum excursion in reactivity of 2.5 percent. This compared to a maximum excursion of 4.2 percent obtained for the same core life when w'anium was uniformly distributed at startup. Boron was incorporated uniformly in these cores at startup. 2. It is possible to approach constant radial heat generation during the life of a cylindrical core by means of startup nonuniform radial and axial distributions of uranium and boron. Results for SCW with nonuniform radial distribution of uranium to provide constant radial heat generation at startup and with boron for longevity indicate relatively small departures from the initially constant radial heat generation distribution during core life. Results for SAR with a sinusoidal

  16. The spatial distribution of ultraviolet line and continuum emission in Herbig-Haro objects

    Science.gov (United States)

    Lee, M. G.; Boehm, K. H.; Temple, S. D.; Raga, A. C.; Mateo, M. L.

    1988-01-01

    Archival IUE data and monochromatic CCD images in the optical range are used to compare the spatial distribution of UV and optical emission in HH 1, HH 2, HH 24, HH 32, HH 43, and HH 47. For all six objects, the observed UV radiation is shown to originate in the objects themselves. The results indicate that the C IV and semiforbidden emission-line regions are small. Although the continuum in the IUE short-wavelength range displays a distribution that is broader than that of any measured line emission in the UV or optical range, the continuum distribution in the IUE long-wavelength range is quite narrow.

  17. [Distribution and spatial ordering of biopolymer molecules in resting bacterial spores].

    Science.gov (United States)

    Duda, V I; Korolev, Iu N; El'-Registan, G I; Duzha, M V; Telegin, N L

    1978-01-01

    The presence, distribution and spatial arrangement of biopolymers in situ were studied in both a total intact spore and in a certain cellular layer using a spectroscopic technique of attenuated total refraction (ATR-IR) in the IR region. In contrast to vegetative cells, intact spores were characterized by isotropic distribution of protein components. This feature can be regarded as an index of the cryptobiotic state of spores. However, the distribution of protein components among individual layers of a spore was anisotropic. Bonds characterized by amide I and amide II bands were most often ordered in a layer which comprised cellular structures from the exosporium to the inner spore membrane.

  18. Spatial distribution of 12 class B notifiable infectious diseases in China: A retrospective study.

    Science.gov (United States)

    Zhu, Bin; Fu, Yang; Liu, Jinlin; Mao, Ying

    2018-01-01

    China is the largest developing country with a relatively developed public health system. To further prevent and eliminate the spread of infectious diseases, China has listed 39 notifiable infectious diseases characterized by wide prevalence or great harm, and classified them into classes A, B, and C, with severity decreasing across classes. Class A diseases have been almost eradicated in China, thus making class B diseases a priority in infectious disease prevention and control. In this retrospective study, we analyze the spatial distribution patterns of 12 class B notifiable infectious diseases that remain active all over China. Global and local Moran's I and corresponding graphic tools are adopted to explore and visualize the global and local spatial distribution of the incidence of the selected epidemics, respectively. Inter-correlations of clustering patterns of each pair of diseases and a cumulative summary of the high/low cluster frequency of the provincial units are also provided by means of figures and maps. Of the 12 most commonly notifiable class B infectious diseases, viral hepatitis and tuberculosis show high incidence rates and account for more than half of the reported cases. Almost all the diseases, except pertussis, exhibit positive spatial autocorrelation at the provincial level. All diseases feature varying spatial concentrations. Nevertheless, associations exist between spatial distribution patterns, with some provincial units displaying the same type of cluster features for two or more infectious diseases. Overall, high-low (unit with high incidence surrounded by units with high incidence, the same below) and high-high spatial cluster areas tend to be prevalent in the provincial units located in western and southwest China, whereas low-low and low-high spatial cluster areas abound in provincial units in north and east China. Despite the various distribution patterns of 12 class B notifiable infectious diseases, certain similarities between

  19. The fractal spatial distribution of pancreatic islets in three dimensions: a self-avoiding growth model

    International Nuclear Information System (INIS)

    Jo, Junghyo; Periwal, Vipul; Hörnblad, Andreas; Ahlgren, Ulf; Kilimnik, German; Hara, Manami

    2013-01-01

    The islets of Langerhans, responsible for controlling blood glucose levels, are dispersed within the pancreas. A universal power law governing the fractal spatial distribution of islets in two-dimensional pancreatic sections has been reported. However, the fractal geometry in the actual three-dimensional pancreas volume, and the developmental process that gives rise to such a self-similar structure, has not been investigated. Here, we examined the three-dimensional spatial distribution of islets in intact mouse pancreata using optical projection tomography and found a power law with a fractal dimension of 2.1. Furthermore, based on two-dimensional pancreatic sections of human autopsies, we found that the distribution of human islets also follows a universal power law with a fractal dimension of 1.5 in adult pancreata, which agrees with the value previously reported in smaller mammalian pancreas sections. Finally, we developed a self-avoiding growth model for the development of the islet distribution and found that the fractal nature of the spatial islet distribution may be associated with the self-avoidance in the branching process of vascularization in the pancreas. (paper)

  20. A Multi-Resolution Spatial Model for Large Datasets Based on the Skew-t Distribution

    KAUST Repository

    Tagle, Felipe

    2017-12-06

    Large, non-Gaussian spatial datasets pose a considerable modeling challenge as the dependence structure implied by the model needs to be captured at different scales, while retaining feasible inference. Skew-normal and skew-t distributions have only recently begun to appear in the spatial statistics literature, without much consideration, however, for the ability to capture dependence at multiple resolutions, and simultaneously achieve feasible inference for increasingly large data sets. This article presents the first multi-resolution spatial model inspired by the skew-t distribution, where a large-scale effect follows a multivariate normal distribution and the fine-scale effects follow a multivariate skew-normal distributions. The resulting marginal distribution for each region is skew-t, thereby allowing for greater flexibility in capturing skewness and heavy tails characterizing many environmental datasets. Likelihood-based inference is performed using a Monte Carlo EM algorithm. The model is applied as a stochastic generator of daily wind speeds over Saudi Arabia.

  1. Spatial distribution modelling of the endangered bivalve Pinna nobilis in a Marine Protected Area

    Directory of Open Access Journals (Sweden)

    M. VÁZQUEZ-LUIS

    2014-09-01

    Full Text Available The spatial distribution of Pinna nobilis densities have been analysed through a geostatistical approach in the MPA of Cabrera National Park, Balearic Islands (Spain, Western Mediterranean Sea. Regression kriging was used to model the effect of environmental variables on the density of living individuals of P. nobilis and generate a predictive map of its distribution within the MPA. The environmental variables considered for the model were: depth; slope; habitat type and heterogeneity; wave exposure; and MPA zoning. A total of 378 transects were randomly distributed with a total of 149,000 m2 surveyed at a depth range from 4.2 to 46 m. The recorded P. nobilis densities are among the highest in the Mediterranean Sea. With respect to the prediction model, results indicate that benthic habitats play a key role in the spatial distribution of P. nobilis, with higher densities in seagrass meadows of Posidonia oceanica. The fan mussel population density peaked at 9 m depth, decreasing with depth. Also, decreasing densities are expected with increasing exposure to waves. The predicted map shows some hotspots of density different in size and distributed along the MPA, and provides valuable information for the spatial conservation management of this species.

  2. Population dynamics and spatial distribution of Abaris basistriata Chaudoir, 1873 (Coleoptera: Carabidae

    Directory of Open Access Journals (Sweden)

    Ivan Carlos Fernandes Martins

    2016-02-01

    Full Text Available ABSTRACT Abaris basistriata, a beetle species dominant in agroecosystems and natural habitats, may benefit from the establishment of nearby refuge areas or crop field centers. To confirm this hypothesis, we analyzed the spatial distribution of the species and verified the population dynamics of this predator in a soybean/corn rotation crop and a central refuge area. The 1-ha experimental area was divided in half by a range of herbaceous plants (2 m in width and 80 m in length. Beetle samples were collected using pitfall traps every fortnight during the in-season and every month during the off-season (a total of 27 sampling occurrences. Population fluctuation was analyzed by correlating the total number of specimens with plant phenology. We used multiple regression analysis with variable (stepwise selection to examine the influence of meteorological factors on species occurrence. To determine the spatial distribution, data were analyzed using dispersion indices and probabilistic models based on the Coleoptera frequency distribution. Distribution visualization was assessed using a linear interpolation map. A total of 143 A. basistriata specimens were collected, with 83 from the soybean/corn area and 60 from the refuge area. Periods of large population size occurred during a season with high rainfall and high maximum and minimum temperatures. On the basis of the spatial distribution analysis of A. basistriata, it is likely that the beetles occur in an aggregate form, preferably in the refuge area.

  3. Fractal spatial distribution of pancreatic islets in three dimensions: a self-avoiding growth model

    Science.gov (United States)

    Jo, Junghyo; Hörnblad, Andreas; Kilimnik, German; Hara, Manami; Ahlgren, Ulf; Periwal, Vipul

    2013-01-01

    The islets of Langerhans, responsible for controlling blood glucose levels, are dispersed within the pancreas. A universal power law governing the fractal spatial distribution of islets in two-dimensional pancreatic sections has been reported. However, the fractal geometry in the actual three-dimensional pancreas volume, and the developmental process that gives rise to such a self-similar structure, have not been investigated. Here, we examined the three-dimensional spatial distribution of islets in intact mouse pancreata using optical projection tomography and found a power law with a fractal dimension, 2.1. Furthermore, based on two-dimensional pancreatic sections of human autopsies, we found that the distribution of human islets also follows a universal power law with fractal dimension 1.5 in adult pancreata, which agrees with the value previously reported in smaller mammalian pancreas sections. Finally, we developed a self-avoiding growth model for the development of the islet distribution and found that the fractal nature of the spatial islet distribution may be associated with the self-avoidance in the branching process of vascularization in the pancreas. PMID:23629025

  4. Structure and Spatial Distribution of Ge Nanocrystals Subjected to Fast Neutron Irradiation

    Directory of Open Access Journals (Sweden)

    Alexander N. Ionov

    2011-07-01

    Full Text Available The influence of fast neutron irradiation on the structure and spatial distribution of Ge nanocrystals (NC embedded in an amorphous SiO2 matrix has been studied. The investigation was conducted by means of laser Raman Scattering (RS, High Resolution Transmission Electron Microscopy (HR-TEM and X-ray photoelectron spectroscopy (XPS. The irradiation of Ge- NC samples by a high dose of fast neutrons lead to a partial destruction of the nanocrystals. Full reconstruction of crystallinity was achieved after annealing the radiation damage at 8000C, which resulted in full restoration of the RS spectrum. HR-TEM images show, however, that the spatial distributions of Ge-NC changed as a result of irradiation and annealing. A sharp decrease in NC distribution towards the SiO2 surface has been observed. This was accompanied by XPS detection of Ge oxides and elemental Ge within both the surface and subsurface region.

  5. Monte Carlo simulations for angular and spatial distributions in therapeutic-energy proton beams

    Science.gov (United States)

    Lin, Yi-Chun; Pan, C. Y.; Chiang, K. J.; Yuan, M. C.; Chu, C. H.; Tsai, Y. W.; Teng, P. K.; Lin, C. H.; Chao, T. C.; Lee, C. C.; Tung, C. J.; Chen, A. E.

    2017-11-01

    The purpose of this study is to compare the angular and spatial distributions of therapeutic-energy proton beams obtained from the FLUKA, GEANT4 and MCNP6 Monte Carlo codes. The Monte Carlo simulations of proton beams passing through two thin targets and a water phantom were investigated to compare the primary and secondary proton fluence distributions and dosimetric differences among these codes. The angular fluence distributions, central axis depth-dose profiles, and lateral distributions of the Bragg peak cross-field were calculated to compare the proton angular and spatial distributions and energy deposition. Benchmark verifications from three different Monte Carlo simulations could be used to evaluate the residual proton fluence for the mean range and to estimate the depth and lateral dose distributions and the characteristic depths and lengths along the central axis as the physical indices corresponding to the evaluation of treatment effectiveness. The results showed a general agreement among codes, except that some deviations were found in the penumbra region. These calculated results are also particularly helpful for understanding primary and secondary proton components for stray radiation calculation and reference proton standard determination, as well as for determining lateral dose distribution performance in proton small-field dosimetry. By demonstrating these calculations, this work could serve as a guide to the recent field of Monte Carlo methods for therapeutic-energy protons.

  6. How vision is shaped by language comprehension--top-down feedback based on low-spatial frequencies.

    Science.gov (United States)

    Hirschfeld, Gerrit; Zwitserlood, Pienie

    2011-03-04

    Effects of language comprehension on visual processing have been extensively studied within the embodied-language framework. However, it is unknown whether these effects are caused by passive repetition suppression in visual processing areas, or depend on active feedback, based on partial input, from prefrontal regions. Based on a model of top-down feedback during visual recognition, we predicted diminished effects when low-spatial frequencies were removed from targets. We compared low-pass and high-pass filtered pictures in a sentence-picture-verification task. Target pictures matched or mismatched the implied shape of an object mentioned in a preceding sentence, or were unrelated to the sentences. As predicted, there was a large match advantage when the targets contained low-spatial frequencies, but no effect of linguistic context when these frequencies were filtered out. The proposed top-down feedback model is superior to repetition suppression in explaining the current results, as well as earlier results about the lateralization of this effect, and peculiar color match effects. We discuss these findings in the context of recent general proposals of prediction and top-down feedback. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique.

    Science.gov (United States)

    Sakuma, Y; Urakami, N; Taniguchi, T; Imai, M

    2011-07-20

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  8. Location-Based Mapping Services to Support Collaboration in Spatially Distributed Workgroups

    Science.gov (United States)

    Meyer, Eike Michael; Wichmann, Daniel; Büsch, Henning; Boll, Susanne

    Mobile devices and systems reached almost every part of our daily life. Following the mobile computing trend, also business logics of distributed, cooperative applications started to move into the mobile client applications. With this shift, the cooperation aspect may also exploit the user’s location and situation context and capabilities of the mobile device and integrate it into the actual cooperation and collaboration. In this paper, we present an approach for a Collaborative Map that exploits the spatial context of the member of a distributed group as a means to visualize and provide collaboration functionality. Then, a number of location-related cooperation methods become feasible such as getting an overview of the spatial distribution of the team members, identify an ad-hoc meeting place nearby, or chat with a group member who has a certain expertise in his or her profile. With CoMa, we move from standard collaboration tools that marginally consider spatial information towards context-aware mobile collaborative systems that can support a wide range of applications such as emergency response, maintenance work or event organization where human resources have to be coordinated in a spatial context and tasks need to be assigned dynamically depending on capabilities and situation context.

  9. Spatial and temporal distribution of carbon dioxide gas using GOSAT data over IRAN.

    Science.gov (United States)

    Falahatkar, Samereh; Mousavi, Seyed Mohsen; Farajzadeh, Manochehr

    2017-11-09

    CO 2 concentration (XCO 2 ) shows the spatial and temporal variation in Iran. The major purpose of this investigation is the assessment of the spatial distribution of carbon dioxide concentration in the different seasons of 2013 based on the Thermal And Near Infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) level 2 GOSAT data by implementing the ordinary kriging (OK) method. In this study, the Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI) data from the MODerate resolution Imaging Spectroradiometer (MODIS), and metrological parameters (temperature and precipitation) were used for the analysis of the spatial distribution of CO 2 over Iran in 2013. The spatial distribution maps of XCO 2 show the highest concentration of this gas in the south and south-east and the lowest concentration in the north and north-west. These results indicate that the concentration of carbon dioxide decreased with the increase of LST and temperature and a decrease of NDVI and humidity in the study area. Therefore, the existence of vegetation has an effective role in capturing carbon from the atmosphere by photosynthesis phenomena, and sustainable land management can be effective for carbon absorption from the atmosphere and mitigation of climate change in arid and semi-arid regions.

  10. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle.

    Science.gov (United States)

    Milligan, R J; Morris, K J; Bett, B J; Durden, J M; Jones, D O B; Robert, K; Ruhl, H A; Bailey, D M

    2016-05-16

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1-10 km(2)) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km(-2) (95% CI: 601-844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km(-2) respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed.

  11. Spatial distribution of the chemical properties of the soil and of soybean yield in the field

    Directory of Open Access Journals (Sweden)

    Alexandre Gazolla-Neto

    2016-06-01

    Full Text Available ABSTRACT The aim of this study was to evaluate the spatial dependence between chemical properties of the soil and yield components in the soybean using precision farming techniques. Samples of the soil and plants were taken from georeferenced points to determine the chemical properties of the soil and the yield components. The results were submitted to Pearson correlation analysis, descriptive statistics and geostatistics. The coefficient of variation showed a wide range of distribution for the chemical attributes of the soil, with the highest indices being found for the levels of available phosphorus (102% and potassium (72.65%. Soil pH and organic matter showed a coefficient of variation of 5.96 and 15.93% respectively. Semivariogram analysis of the yield components (productivity, 1,000-seed weight and number of seeds and the chemical properties of the soil (organic matter, pH, phosphorus, potassium, calcium, magnesium, boron, manganese and zinc fitted the spherical model with moderate spatial dependence, with values ranging from 200 to 700 m. Spatial distribution by means of map interpolation was efficient in evaluating spatial variability, allowing the identification and quantification of regions of low and high productivity in the production area, together with the distribution of soil attributes and their respective levels of availability to the soybean plants.

  12. Applying Spatially Distributed Rainfall to a Hydrological Model in a Tropical Watershed, Manoa Watershed, in Hawaii

    Science.gov (United States)

    Huang, Y. F.; Tsang, Y. P.

    2017-12-01

    Rainfall in Hawaii is characterized with high spatial and temporal variability. In the south side of Oahu, the Manoa watershed, with an area of 11 km2, has the annual maximum rainfall of 3900mm and the minimum rainfall of 1000 mm. Despite this high spatial heterogeneity, the rain gage network seems insufficiently capture this pattern. When simulating stream flow and predicting floods with hydrological models in Hawaii, the model performance is often unsatisfactory because of inadequate representation of rainfall data. Longman et al. (in prep.) have developed the spatially distributed daily rainfall across the Hawaiian Islands by applying ordinary kriging, yet these data have not been applied to hydrological models. In this study, we used the Soil and Water Assessment Tool (SWAT) model to assess the streamflow simulation by applying spatially-distributed rainfall in the Manoa watershed. We first used point daily-rainfall at Lyon Arboretum from National Center of Environmental Information (NCEI) as the uniform rainfall input. Secondly, we summarized sub-watershed mean rainfall from the daily spatial-statistical rainfall. Both rainfall data are available from 1999 to 2014. The SWAT was set up for five-year warm-up, nine-year calibration, and two-year validation. The model parameters were calibrated and validated with four U.S. Geological Survey stream gages. We compared the calibrated watershed parameters, characteristics, and assess the streamflow hydrographs from these two rainfall inputs. The differences and improvement of using spatially distributed rainfall input in SWAT were discussed. In addition to improving the model by the representation of rainfall, this study helped us having a better understanding of the watershed hydrological response in Hawaii.

  13. Theoretical and experimental study on the temperature distribution of H-shaped steel members under solar radiation

    International Nuclear Information System (INIS)

    Liu Hongbo; Chen Zhihua; Zhou Ting

    2012-01-01

    Thermal effects on steel structures exposed to solar radiation are significant and complicated. Furthermore, the temperature variation within a year may result in damage in steel structures considering the solar radiation. In this paper, the temperature distribution of H-shaped steel members was investigated through a systematic experimental and theoretical study in the case of solar radiation. First, an H-shaped steel specimen was designed and its temperature distribution under solar radiation was obtained by a test. After that, a numerical method was proposed to obtain the temperature distribution under solar radiation. This method was based on transient thermal analysis and the analytical result was verified by the above experimental result. Furthermore, a parametric study was conducted to investigate the influence of various solar radiation parameters and orientation of H-shaped steel members on the temperature distribution under solar radiation. Finally, a simplified approach was developed to predict the temperature distribution under solar radiation. Both experimental and numerical results showed that the solar radiation had a significant effect on the temperature distribution of H-shaped steels. Considering the solar radiation, the temperature of the specimen is about 20.6 °C higher than the surrounding ambient air temperature. The temperature distribution under solar radiation was observed to be sensitive to the steel solar radiation absorption and orientation, but insensitive to the solar radiation reflectance. - Highlights: ► The temperature of H-shaped steel members was measured under solar radiation. ► A numerical method was proposed to consider the shadow of solar radiation. ► A parametric study was conducted. ► A simplified approach for temperature distribution was developed and verified.

  14. The effect of vertical velocity probability distribution shape on cloud activation of aerosols: off-line calculations

    Science.gov (United States)

    Tonttila, J.; Romakkaniemi, S.; Räisänen, P.; Kokkola, H.; Järvinen, H.

    2012-04-01

    Off-line calculations of cloud activation of aerosols using a probability density function (PDF) for vertical velocity (w) are performed. The focus is on the variation of the shape of the PDF using two functional formulations: the Normal distribution PDF and the Pearson type IV PDF. The Normal distribution provides a familiar example, as it has been widely used to approximate vertical velocity distributions in numerous applications, including climate models. Pearson type IV distribution provides an alternative that, to our knowledge, has not been employed before to describe the vertical velocity PDF. The advantage of the Pearson distribution is its versatility in representing skewed and more peaked distribution shapes compared to the Normal distribution, though this is obtained at the expense of increased mathematical complexity. The experiments are performed using a box model, in which the environmental conditions, including the aerosol size distribution (bi-modal) and chemical composition (ammonium-sulphate particles) are prescribed as constants. Measured size distributions comprising clean and polluted cases are used. Cloud activation of aerosols is calculated by integrating over the positive side of the PDF of w, which yields the mean number of activated particles (Nact). The mean, variance, and skewness of the PDFs along with the type of the PDF itself are altered in order to explore the effect of the PDF shape on the activation process. All experiments are repeated for three well-documented activation parameterizations: Lin & Leaitch, Abdul-Razzak & Ghan and Fountoukis & Nenes. The results show that for symmetric distributions of w (skewness = 0) there is a maximum difference of 10-15 % in Nact between the cases with w given by the Normal distribution, and the more peaked Pearson distribution. The largest differences are seen for the most polluted cases. Nact in clean cases will saturate rather quickly with respect to the maximum supersaturation and, hence

  15. Calibration of a distributed hydrologic model using observed spatial patterns from MODIS data

    Science.gov (United States)

    Demirel, Mehmet C.; González, Gorka M.; Mai, Juliane; Stisen, Simon

    2016-04-01

    Distributed hydrologic models are typically calibrated against streamflow observations at the outlet of the basin. Along with these observations from gauging stations, satellite based estimates offer independent evaluation data such as remotely sensed actual evapotranspiration (aET) and land surface temperature. The primary objective of the study is to compare model calibrations against traditional downstream discharge measurements with calibrations against simulated spatial patterns and combinations of both types of observations. While the discharge based model calibration typically improves the temporal dynamics of the model, it seems to give rise to minimum improvement of the simulated spatial patterns. In contrast, objective functions specifically targeting the spatial pattern performance could potentially increase the spatial model performance. However, most modeling studies, including the model formulations and parameterization, are not designed to actually change the simulated spatial pattern during calibration. This study investigates the potential benefits of incorporating spatial patterns from MODIS data to calibrate the mesoscale hydrologic model (mHM). This model is selected as it allows for a change in the spatial distribution of key soil parameters through the optimization of pedo-transfer function parameters and includes options for using fully distributed daily Leaf Area Index (LAI) values directly as input. In addition the simulated aET can be estimated at a spatial resolution suitable for comparison to the spatial patterns observed with MODIS data. To increase our control on spatial calibration we introduced three additional parameters to the model. These new parameters are part of an empirical equation to the calculate crop coefficient (Kc) from daily LAI maps and used to update potential evapotranspiration (PET) as model inputs. This is done instead of correcting/updating PET with just a uniform (or aspect driven) factor used in the mHM model

  16. Spatial distribution of Na+-K+-ATPase in dendritic spines dissected by nanoscale superresolution STED microscopy

    Directory of Open Access Journals (Sweden)

    Bondar Alexander

    2011-01-01

    Full Text Available Abstract Background The Na+,K+-ATPase plays an important role for ion homeostasis in virtually all mammalian cells, including neurons. Despite this, there is as yet little known about the isoform specific distribution in neurons. Results With help of superresolving stimulated emission depletion microscopy the spatial distribution of Na+,K+-ATPase in dendritic spines of cultured striatum neurons have been dissected. The found compartmentalized distribution provides a strong evidence for the confinement of neuronal Na+,K+-ATPase (α3 isoform in the postsynaptic region of the spine. Conclusions A compartmentalized distribution may have implications for the generation of local sodium gradients within the spine and for the structural and functional interaction between the sodium pump and other synaptic proteins. Superresolution microscopy has thus opened up a new perspective to elucidate the nature of the physiological function, regulation and signaling role of Na+,K+-ATPase from its topological distribution in dendritic spines.

  17. Spatial distribution of groundwater quality with special emphasis on fluoride of Mandvi Taluka, Surat, Gujarat, India

    Science.gov (United States)

    Prajapati, Mayuri; Jariwala, Namrata; Agnihotri, Prasit

    2017-12-01

    The present study deals with the groundwater quality with respect to F- in the Mandavi Taluka of Surat city with an objective to analyze the spatial variability of ground water quality parameter. A total 57 representative groundwater samples from different bore wells and hand pumps were collected during pre-monsoon. Samples were analyzed for various physiochemical parameters including fluoride. GIS technique is adopted to prepare DEM and spatial distribution map of fluoride to represent fluoride concentration in the study area. Results obtained from analysis with GIS mapping reveal that fluoride in the study is mainly attributed to geogenic source.

  18. Spatial distribution of enzyme activities along the root and in the rhizosphere of different plants

    Science.gov (United States)

    Razavi, Bahar S.; Zarebanadkouki, Mohsen; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2015-04-01

    Extracellular enzymes are important for decomposition of many biological macromolecules abundant in soil such as cellulose, hemicelluloses and proteins. Activities of enzymes produced by both plant roots and microbes are the primary biological drivers of organic matter decomposition and nutrient cycling. So far acquisition of in situ data about local activity of different enzymes in soil has been challenged. That is why there is an urgent need in spatially explicit methods such as 2-D zymography to determine the variation of enzymes along the roots in different plants. Here, we developed further the zymography technique in order to quantitatively visualize the enzyme activities (Spohn and Kuzyakov, 2013), with a better spatial resolution We grew Maize (Zea mays L.) and Lentil (Lens culinaris) in rhizoboxes under optimum conditions for 21 days to study spatial distribution of enzyme activity in soil and along roots. We visualized the 2D distribution of the activity of three enzymes:β-glucosidase, leucine amino peptidase and phosphatase, using fluorogenically labelled substrates. Spatial resolution of fluorescent images was improved by direct application of a substrate saturated membrane to the soil-root system. The newly-developed direct zymography shows different pattern of spatial distribution of enzyme activity along roots and soil of different plants. We observed a uniform distribution of enzyme activities along the root system of Lentil. However, root system of Maize demonstrated inhomogeneity of enzyme activities. The apical part of an individual root (root tip) in maize showed the highest activity. The activity of all enzymes was the highest at vicinity of the roots and it decreased towards the bulk soil. Spatial patterns of enzyme activities as a function of distance from the root surface were enzyme specific, with highest extension for phosphatase. We conclude that improved zymography is promising in situ technique to analyze, visualize and quantify

  19. Spatial distribution of calcium-gated chloride channels in olfactory cilia.

    Science.gov (United States)

    French, Donald A; Badamdorj, Dorjsuren; Kleene, Steven J

    2010-12-30

    In vertebrate olfactory receptor neurons, sensory cilia transduce odor stimuli into changes in neuronal membrane potential. The voltage changes are primarily caused by the sequential openings of two types of channel: a cyclic-nucleotide-gated (CNG) cationic channel and a calcium-gated chloride channel. In frog, the cilia are 25 to 200 µm in length, so the spatial distributions of the channels may be an important determinant of odor sensitivity. To determine the spatial distribution of the chloride channels, we recorded from single cilia as calcium was allowed to diffuse down the length of the cilium and activate the channels. A computational model of this experiment allowed an estimate of the spatial distribution of the chloride channels. On average, the channels were concentrated in a narrow band centered at a distance of 29% of the ciliary length, measured from the base of the cilium. This matches the location of the CNG channels determined previously. This non-uniform distribution of transduction proteins is consistent with similar findings in other cilia. On average, the two types of olfactory transduction channel are concentrated in the same region of the cilium. This may contribute to the efficient detection of weak stimuli.

  20. Applications of Geographical Information Systems in Understanding Spatial Distribution of Asthma

    Directory of Open Access Journals (Sweden)

    Mohammad A. Rob

    2003-01-01

    Full Text Available Geographical Information Systems (GIS are becoming useful tools in making strategic decisions when-ever data are found to have spatial distribution. Federal, state, and local governments are using GIS for assessment and planning in such areas as housing, healthcare, land use, natural resources, environmental monitoring and transportation. Companies are also using it to expand and consolidate existing businesses, perform market analysis, and to find optimum delivery routes. In this paper, we illustrate the usefulness of GIS in the analysis and presentation of spatially distributed asthma prevalence among school children (13-17 years in the New York City area. To the best of our knowledge, this is the first presentation of asthma survey results distributed over the zip codes of a large city. Preliminary results show good correlation between asthma and poverty. They also correlate well with the spatial distribution of asthma hospitalization data. Results reveal an overall asthma prevalence of ~ 16% as compared to the national average of ~12% for a similar age group (5-17 years. When comparing asthma rates among the predominant racial groups of the city - Blacks and Hispanics are found to have a higher prevalence than Whites or Asians. The inner-city population shows a significantly higher asthma prevalence than those in the suburbs. This study shows our understanding of asthma prevalence in a dimension that could not have been possible prior to the availability of GIS. The results will help us making further decisions in planning for asthma research.

  1. Evaluation and mapping spatial distribution of bottom sediment heavy metal contamination in Burullus Lake, Egypt

    Directory of Open Access Journals (Sweden)

    Yasser A. El-Amier

    2017-03-01

    Full Text Available Burullus Lake is one of most important lakes in north Delta of Egypt. It is exposed to huge amounts of serious pollutants especially heavy metals. The sediments within the lake aid in the dispersion of these metals. The main objectives of this research were to evaluate and map the spatial distribution of heavy metals in Burullus Lake sediments. Accordingly, 37 locations were randomly distributed within the lake. Sediment samples were taken from these locations. These samples were analyzed for seven metals including Fe, Cu, Zn, Cr, Co, Cd and Pb. Also, five indices were used to identify the status of metal pollutants in the Lake. These indices are: enrichment factor (EF, contamination factor (CF, degree of contamination (DC, pollution load index (PLI and geo-accumulation index (Igeo. Ordinary Kriging was used to interpolate the spatial distribution of the studied elements within the lake. The obtained results indicated that cadmium was the most enriched element in the lake sediments due to industrial and agricultural wastes drained into the lake. The Igeo index revealed that Cd and Pb were the common pollutants in lake sediments. The DC values ranged between low (near El-Boughaz and moderate (near drainage areas. The spatial distribution of pollutants within the lake indicated that the highly polluted areas are located close to the drains, whereas as the less polluted areas were close to El-Boughaz.

  2. Sodium Atoms in the Lunar Exotail: Observed Velocity and Spatial Distributions

    Science.gov (United States)

    Line, Michael R.; Mierkiewicz, E. J.; Oliversen, R. J.; Wilson, J. K.; Haffner, L. M.; Roesler, F. L.

    2011-01-01

    The lunar sodium tail extends long distances due to radiation pressure on sodium atoms in the lunar exosphere. Our earlier observations determined the average radial velocity of sodium atoms moving down the lunar tail beyond Earth along the Sun-Moon-Earth line (i.e., the anti-lunar point) to be 12.4 km/s. Here we use the Wisconsin H-alpha Mapper to obtain the first kinematically resolved maps of the intensity and velocity distribution of this emission over a 15 x times 15 deg region on the sky near the anti-lunar point. We present both spatially and spectrally resolved observations obtained over four nights around new moon in October 2007. The spatial distribution of the sodium atoms is elongated along the ecliptic with the location of the peak intensity drifting 3 degrees east along the ecliptic per night. Preliminary modeling results suggest that the spatial and velocity distributions in the sodium exotail are sensitive to the near surface lunar sodium velocity distribution and that observations of this sort along with detailed modeling offer new opportunities to describe the time history of lunar surface sputtering over several days.

  3. New ecological mechanism of formation of spatial distribution of radionuclides in river ecosystem

    International Nuclear Information System (INIS)

    Degermendzhy, A.G.; Shevyrnogov, A.P.; Kosolapova, L.G.; Levin, L.A.; Chernousov, A.V.; Vlasik, P.V.

    1996-01-01

    Radioecological expeditions on the Yenissei river revealed 'spotty' distribution of radioisotopes in bottom sediments and along the coastline of the river. This work presents results of theoretical analysis of the formation mechanism of stable spatial non-uniformities of river ecosystem components by population interactions of 'predator-prey' type between the phytoplukton and zooplankton. 'Patchiness contrast' (i.e. the amplitude of the radionuclide spatial propagation wave in the water) for the large oscillations control by increasing or decreasing current velocity depends both on the boundary concentrations of phytoplankton and zooplankton and on the established nature of their interpopulation interactions (or coefficients of interactions). Variation of the below given interaction parameters within the 'phytoplanbon-zooplankton' system makes increase the amplitude of spatial distribution wave: decrease of algal growth rate; increase of algal death rate; decrease of zooplankton death rate; increase of interaction coefficients. It was shown for small oscillations that the period of component distribution waves is in proportion to the current velocity and the amplitude of 'small' waves does not depend on the water current velocity. Theoretically it has been also found that with deep limitation of phytoplankton growth by biogenous elements the 'standing wave' is observed to deteriorate and monotonous distribution of radionuclide concentration fields is found to form. (author)

  4. Spatial distribution of the source-receptor relationship of sulfur in Northeast Asia

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    M. Kajino

    2011-07-01

    Full Text Available The spatial distribution of the source-receptor relationship (SRR of sulfur over Northeast Asia was examined using a chemical transport model (RAQM off-line coupled with a meteorological model (MM5. The simulation was conducted for the entire year of 2002. The results were evaluated using monitoring data for six remote stations of the Acid Deposition Monitoring Network in East Asia (EANET. The modeled SO2 and O3 concentrations agreed well with the observations quantitatively. The modeled aerosol and wet deposition fluxes of SO42− were underestimated by 30 % and 50 %, respectively. The domain was divided into 5 source-receptor regions: (I North China; (II Central China; (III South China; (IV South Korea; and (V Japan. The sulfur deposition in each receptor region amounted to about 50–75 % of the emissions from the same region. The largest contribution to the deposition in each region was originated from the same region, accounting for 53–84 %. The second largest contribution was due to Region II, supplying 14–43 %. The spatial distributions of the SRRs revealed that subregional values varied by about two times more than regional averages due to nonuniformity across the deposition fields. Examining the spatial distributions of the deposition fields was important for identifying subregional areas where the deposition was highest within a receptor region. The horizontal distribution changed substantially according to season.

  5. Local and latitudinal variation in abundance: the mechanisms shaping the distribution of an ecosystem engineer.

    Science.gov (United States)

    Crutsinger, Gregory M; Gonzalez, Angélica L; Crawford, Kerri M; Sanders, Nathan J

    2013-01-01

    Ecological processes that determine the abundance of species within ecological communities vary across space and time. These scale-dependent processes are especially important when they affect key members of a community, such as ecosystem engineers that create shelter and food resources for other species. Yet, few studies have examined the suite of processes that shape the abundance of ecosystem engineers. Here, we evaluated the relative influence of temporal variation, local processes, and latitude on the abundance of an engineering insect-a rosette-galling midge, Rhopalomyia solidaginis (Diptera: Cecidomyiidae). Over a period of 3-5 years, we studied the density and size of galls across a suite of local experiments that manipulated genetic variation, soil nutrient availability, and the removal of other insects from the host plant, Solidago altissima (tall goldenrod). We also surveyed gall density within a single growing season across a 2,300 km latitudinal transect of goldenrod populations in the eastern United States. At the local scale, we found that host-plant genotypic variation was the best predictor of rosette gall density and size within a single year. We found that the removal of other insect herbivores resulted in an increase in gall density and size. The amendment of soil nutrients for four years had no effect on gall density, but galls were smaller in carbon-added plots compared to control and nitrogen additions. Finally, we observed that gall density varied several fold across years. At the biogeographic scale, we observed that the density of rosette gallers peaked at mid-latitudes. Using meta-analytic approaches, we found that the effect size of time, followed by host-plant genetic variation and latitude were the best predictors of gall density. Taken together, our study provides a unique comparison of multiple factors across different spatial and temporal scales that govern engineering insect herbivore density.

  6. Long-term spatial heterogeneity in mallard distribution in the Prairie pothole region

    Science.gov (United States)

    Janke, Adam K.; Anteau, Michael J.; Stafford, Joshua D.

    2017-01-01

    The Prairie Pothole Region (PPR) of north-central United States and south-central Canada supports greater than half of all breeding mallards (Anas platyrhynchos) annually counted in North America and is the focus of widespread conservation and research efforts. Allocation of conservation resources for this socioeconomically important population would benefit from an understanding of the nature of spatiotemporal variation in distribution of breeding mallards throughout the 850,000 km2 landscape. We used mallard counts from the Waterfowl Breeding Population and Habitat Survey to test for spatial heterogeneity and identify high- and low-abundance regions of breeding mallards over a 50-year time series. We found strong annual spatial heterogeneity in all years: 90% of mallards counted annually were on an average of only 15% of surveyed segments. Using a local indicator of spatial autocorrelation, we found a relatively static distribution of low-count clusters in northern Montana, USA, and southern Alberta, Canada, and a dynamic distribution of high-count clusters throughout the study period. Distribution of high-count clusters shifted southeast from northwestern portions of the PPR in Alberta and western Saskatchewan, Canada, to North and South Dakota, USA, during the latter half of the study period. This spatial redistribution of core mallard breeding populations was likely driven by interactions between environmental variation that created favorable hydrological conditions for wetlands in the eastern PPR and dynamic land-use patterns related to upland cropping practices and government land-retirement programs. Our results highlight an opportunity for prioritizing relatively small regions within the PPR for allocation of wetland and grassland conservation for mallard populations. However, the extensive spatial heterogeneity in core distributions over our study period suggests such spatial prioritization will have to overcome challenges presented by dynamic land

  7. Phenotypic plasticity influences the size, shape and dynamics of the geographic distribution of an invasive plant.

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    Jean-Baptiste Pichancourt

    Full Text Available Phenotypic plasticity has long been suspected to allow invasive species to expand their geographic range across large-scale environmental gradients. We tested this possibility in Australia using a continental scale survey of the invasive tree Parkinsonia aculeata (Fabaceae in twenty-three sites distributed across four climate regions and three habitat types. Using tree-level responses, we detected a trade-off between seed mass and seed number across the moisture gradient. Individual trees plastically and reversibly produced many small seeds at dry sites or years, and few big seeds at wet sites and years. Bigger seeds were positively correlated with higher seed and seedling survival rates. The trade-off, the relation between seed mass, seed and seedling survival, and other fitness components of the plant life-cycle were integrated within a matrix population model. The model confirms that the plastic response resulted in average fitness benefits across the life-cycle. Plasticity resulted in average fitness being positively maintained at the wet and dry range margins where extinction risks would otherwise have been high ("Jack-of-all-Trades" strategy JT, and fitness being maximized at the species range centre where extinction risks were already low ("Master-of-Some" strategy MS. The resulting hybrid "Jack-and-Master" strategy (JM broadened the geographic range and amplified average fitness in the range centre. Our study provides the first empirical evidence for a JM species. It also confirms mechanistically the importance of phenotypic plasticity in determining the size, the shape and the dynamic of a species distribution. The JM allows rapid and reversible phenotypic responses to new or changing moisture conditions at different scales, providing the species with definite advantages over genetic adaptation when invading diverse and variable environments. Furthermore, natural selection pressure acting on phenotypic plasticity is predicted to result

  8. How well do food distributions predict spatial distributions of shorebirds with different degrees of self-organization?

    Science.gov (United States)

    Folmer, Eelke O; Olff, Han; Piersma, Theunis

    2010-07-01

    1. Habitat selection models usually assume that the spatial distributions of animals depend positively on the distributions of resources and negatively on interference. However, the presence of conspecifics at a given location also signals safety and the availability of resources. This may induce followers to select contiguous patches and causes animals to cluster. Resource availability, interference and attraction therefore jointly lead to self-organized patterns in foraging animals. 2. We analyse the distribution of foraging shorebirds at landscape level on the basis of a resource-based model to establish, albeit indirectly, the importance of conspecific attraction and interference. 3. At 23 intertidal sites with a mean area of 170 ha spread out over the Dutch Wadden Sea, the spatial distribution of six abundant shorebird species was determined. The location of individuals and groups was mapped using a simple method based on projective geometry, enabling fast mapping of low-tide foraging shorebird distributions. We analysed the suitability of these 23 sites in terms of food availability and travel distances to high tide roosts. 4. We introduce an interference sensitivity scale which maps interference as a function of inter-individual distance. We thus obtain interference-insensitive species, which are only sensitive to interference at short inter-individual distances (and may thus pack densely) and interference-sensitive species which interfere over greater inter-individual distances (and thus form sparse flocks). 5. We found that interference-insensitive species like red knot (Calidris canutus) and dunlins (Calidris alpina) are more clustered than predicted by the spatial distribution of their food resources. This suggests that these species follow each other when selecting foraging patches. In contrast, curlew (Numenius arquata) and grey plover (Pluvialis squatarola), known to be sensitive to interference, form sparse flocks. Hence, resource-based models have

  9. How evolving heterogeneity distributions of resource allocation strategies shape mortality patterns.

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    Yann Le Cunff

    Full Text Available It is well established that individuals age differently. Yet the nature of these inter-individual differences is still largely unknown. For humans, two main hypotheses have been recently formulated: individuals may experience differences in aging rate or aging timing. This issue is central because it directly influences predictions for human lifespan and provides strong insights into the biological determinants of aging. In this article, we propose a model which lets population heterogeneity emerge from an evolutionary algorithm. We find that whether individuals differ in (i aging rate or (ii timing leads to different emerging population heterogeneity. Yet, in both cases, the same mortality patterns are observed at the population level. These patterns qualitatively reproduce those of yeasts, flies, worms and humans. Such findings, supported by an extensive parameter exploration, suggest that mortality patterns across species and their potential shapes belong to a limited and robust set of possible curves. In addition, we use our model to shed light on the notion of subpopulations, link population heterogeneity with the experimental results of stress induction experiments and provide predictions about the expected mortality patterns. As biology is moving towards the study of the distribution of individual-based measures, the model and framework we propose here paves the way for evolutionary interpretations of empirical and experimental data linking the individual level to the population level.

  10. Effect of laser beam on temperature distribution on artificial cylindrical shaped hard tissue bones

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Qaseer, Mohammad-Khair; Albiss, B. A.; Gezawa, Umar S.

    2018-02-01

    Samples from fresh lamb chest bones were made in cylindrical shapes to study the time variation of temperature T as functions of the cylindrical radius and depth when its front surface exposed to a laser beam of 110Mw power and 642nm wavelength. The laser beam was directed at the center of the front surface of the horizontal cylinder. The measurements were done in vacuum and at atmospheric pressure. Our data reveal the linear variation of T with time, followed by a gradual increase before it reaches a plateau value at higher time. This sort of behavior independent of the radius or the depth where the temperature was measured. Moreover, the maximum variation occurs on the front surface where the laser beam was hitting and diminishes gradually with depth deep inside the cylinder. Data at atmospheric pressure showed less changes in temperature. The temperature distribution in bone due to laser irradiation is very important for a rational use of laser therapy as well as in the surgery to minimizes the thermal tissue damage.

  11. History Shaped the Geographic Distribution of Genomic Admixture on the Island of Puerto Rico

    Science.gov (United States)

    Via, Marc; Gignoux, Christopher R.; Roth, Lindsey A.; Fejerman, Laura; Galanter, Joshua; Choudhry, Shweta; Toro-Labrador, Gladys; Viera-Vera, Jorge; Oleksyk, Taras K.; Beckman, Kenneth; Ziv, Elad; Risch, Neil

    2011-01-01

    Contemporary genetic variation among Latin Americans human groups reflects population migrations shaped by complex historical, social and economic factors. Consequently, admixture patterns may vary by geographic regions ranging from countries to neighborhoods. We examined the geographic variation of admixture across the island of Puerto Rico and the degree to which it could be explained by historic and social events. We analyzed a census-based sample of 642 Puerto Rican individuals that were genotyped for 93 ancestry informative markers (AIMs) to estimate African, European and Native American ancestry. Socioeconomic status (SES) data and geographic location were obtained for each individual. There was significant geographic variation of ancestry across the island. In particular, African ancestry demonstrated a decreasing East to West gradient that was partially explained by historical factors linked to the colonial sugar plantation system. SES also demonstrated a parallel decreasing cline from East to West. However, at a local level, SES and African ancestry were negatively correlated. European ancestry was strongly negatively correlated with African ancestry and therefore showed patterns complementary to African ancestry. By contrast, Native American ancestry showed little variation across the island and across individuals and appears to have played little social role historically. The observed geographic distributions of SES and genetic variation relate to historical social events and mating patterns, and have substantial implications for the design of studies in the recently admixed Puerto Rican population. More generally, our results demonstrate the importance of incorporating social and geographic data with genetics when studying contemporary admixed populations. PMID:21304981

  12. Effect of electrode density and measurement noise on the spatial resolution of cortical potential distribution.

    Science.gov (United States)

    Ryynänen, Outi R M; Hyttinen, Jari A K; Laarne, Päivi H; Malmivuo, Jaakko A

    2004-09-01

    The purpose of the present study was to examine the spatial resolution of electroencephalography (EEG) by means of inverse cortical EEG solution. The main interest was to study how the number of measurement electrodes and the amount of measurement noise affects the spatial resolution. A three-layer spherical head model was used to obtain the source-field relationship of cortical potentials and scalp EEG field. Singular value decomposition was used to evaluate the spatial resolution with various measurement noise estimates. The results suggest that as the measurement noise increases the advantage of dense electrode systems is decreased. With low realistic measurement noise, a more accurate inverse cortical potential distribution can be obtained with an electrode system where the distance between two electrodes is as small as 16 mm, corresponding to as many as 256 measurement electrodes. In clinical measurement environments, it is always beneficial to have at least 64 measurement electrodes.

  13. Spatial beam shaping using a micro-structured optical fiber and all-fiber laser amplification system for large-scale laser facilities seeding

    International Nuclear Information System (INIS)

    Calvet, Pierre

    2014-01-01

    Spatial beam shaping is an important topic for the lasers applications. For various industrial areas (marking, drilling, laser-matter interaction, high-power laser seeding...) the optical beam has to be flattened. Currently, the state of the art of the beam shaping: 'free-space' solutions or highly multimode fibers, are not fully suitable. The first ones are very sensitive to any perturbations and the maintenance is challenging, the second ones cannot deliver a coherent beam. For this reason, we present in this manuscript a micro-structured optical single-mode fiber delivering a spatially flattened beam. This 'Top-Hat' fiber can shape any beam in a spatially coherent beam what is a progress with respect to the highly multimode fibers used in the state of the art. The optical fibers are easy to use and very robust, what is a strong benefit with respect to the 'free-space' solutions. Thanks to this fiber, we could realize an all-fiber multi-stage laser chain to amplify a 10 ns pulse to 100 μJ. Moreover the temporal, spectral and spatial properties were preserved. We adapted this 'Top-Hat' fiber to this multi-stage laser chain, we proved the capability and the interest of this fiber for the spatial beam shaping of the laser beams in highly performing and robust laser systems. (author) [fr

  14. Spatial distribution and interspecific associations of tree species in a tropical seasonal rain forest of China.

    Directory of Open Access Journals (Sweden)

    Guoyu Lan

    Full Text Available Studying the spatial pattern and interspecific associations of plant species may provide valuable insights into processes and mechanisms that maintain species coexistence. Point pattern analysis was used to analyze the spatial distribution patterns of twenty dominant tree species, their interspecific spatial associations and changes across life stages in a 20-ha permanent plot of seasonal tropical rainforest in Xishuangbanna, China, to test mechanisms maintaining species coexistence. Torus-translation tests were used to quantify positive or negative associations of the species to topographic habitats. The results showed: (1 fourteen of the twenty tree species were negatively (or positively associated with one or two of the topographic variables, which evidences that the niche contributes to the spatial pattern of these species. (2 Most saplings of the study species showed a significantly clumped distribution at small scales (0-10 m which was lost at larger scales (10-30 m. (3 The degree of spatial clumping deceases from saplings, to poles, to adults indicates that density-dependent mortality of the offspring is ubiquitous in species. (4 It is notable that a high number of positive small-scale interactions were found among the twenty species. For saplings, 42.6% of all combinations of species pairs showed positive associations at neighborhood scales up to five meters, but only 38.4% were negative. For poles and adults, positive associations at these distances still made up 45.5% and 29.5%, respectively. In conclusion, there is considerable evidence for the presence of positive interactions among the tree species, which suggests that species herd protection may occur in our plot. In addition, niche assembly and limited dispersal (likely contribute to the spatial patterns of tree species in the tropical seasonal rain forest in Xishuangbanna, China.

  15. Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM

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    Mahdieh eKhanmohammadi

    2015-09-01

    Full Text Available The spatial interactions of synaptic vesicles in synapses were assessed after a detailed characterization of size, shape, and orientation of the synaptic vesicles. We hypothesized that shape and orientation of the synaptic vesicles are influenced by their movement towards the active zone causing deviations from spherical shape and systematic trends in their orientation.We studied three-dimensional representations of synapses obtained by manual annotation of focused ion beam scanning electron microscopy (FIB-SEM images of male mouse brain. The configurations of synaptic vesicles were regarded as marked point patterns, where the points are the centers of the vesicles, and the mark of a vesicle is given by its size, shape, and orientation characteristics. Statistics for marked point processes were employed to study spatial interactions between vesicles.We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation towards the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them, beyond that caused by their physical extent.

  16. Using geomorphological variables to predict the spatial distribution of plant species in agricultural drainage networks.

    Science.gov (United States)

    Rudi, Gabrielle; Bailly, Jean-Stéphane; Vinatier, Fabrice

    2018-01-01

    To optimize ecosystem services provided by agricultural drainage networks (ditches) in headwater catchments, we need to manage the spatial distribution of plant species living in these networks. Geomorphological variables have been shown to be important predictors of plant distribution in other ecosystems because they control the water regime, the sediment deposition rates and the sun exposure in the ditches. Whether such variables may be used to predict plant distribution in agricultural drainage networks is unknown. We collected presence and absence data for 10 herbaceous plant species in a subset of a network of drainage ditches (35 km long) within a Mediterranean agricultural catchment. We simulated their spatial distribution with GLM and Maxent model using geomorphological variables and distance to natural lands and roads. Models were validated using k-fold cross-validation. We then compared the mean Area Under the Curve (AUC) values obtained for each model and other metrics issued from the confusion matrices between observed and predicted variables. Based on the results of all metrics, the models were efficient at predicting the distribution of seven species out of ten, confirming the relevance of geomorphological variables and distance to natural lands and roads to explain the occurrence of plant species in this Mediterranean catchment. In particular, the importance of the landscape geomorphological variables, ie the importance of the geomorphological features encompassing a broad environment around the ditch, has been highlighted. This suggests that agro-ecological measures for managing ecosystem services provided by ditch plants should focus on the control of the hydrological and sedimentological connectivity at the catchment scale. For example, the density of the ditch network could be modified or the spatial distribution of vegetative filter strips used for sediment trapping could be optimized. In addition, the vegetative filter strips could constitute

  17. Artificial neural networks for spatial distribution of fuel assemblies in reload of PWR reactors

    International Nuclear Information System (INIS)

    Oliveira, Edyene; Castro, Victor F.; Velásquez, Carlos E.; Pereira, Claubia

    2017-01-01

    An artificial neural network methodology is being developed in order to find an optimum spatial distribution of the fuel assemblies in a nuclear reactor core during reload. The main bounding parameter of the modelling was the neutron multiplication factor, k ef f . The characteristics of the network are defined by the nuclear parameters: cycle, burnup, enrichment, fuel type, and average power peak of each element. These parameters were obtained by the ORNL nuclear code package SCALE6.0. As for the artificial neural network, the ANN Feedforward Multi L ayer P erceptron with various layers and neurons were constructed. Three algorithms were used and tested: LM (Levenberg-Marquardt), SCG (Scaled Conjugate Gradient) and BayR (Bayesian Regularization). Artificial neural network have implemented using MATLAB 2015a version. As preliminary results, the spatial distribution of the fuel assemblies in the core using a neural network was slightly better than the standard core. (author)

  18. Spatial distribution of metals in urban topsoils of Xuzhou (China): controlling factors and environmental implications

    Science.gov (United States)

    Wang, Xue-Song; Qin, Yong

    2006-03-01

    The contamination of soils by metals from various sources is a subject of increasing concern in recent times. Twenty-eight elements (Fe, Ti, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag and Sn) have been analyzed from urban topsoil from the city of Xuzhou. The concentrations of these analyzed elements have been correlated to some soil parameters such as organic matter, pH, cation exchange capacity, carbonate content, and granulometric fractions (clay, silt and sand). Results of the statistical analysis show a large variety and complexity in these relationships. The spatial distributions of these metal concentrations were also constructed using geographical information system. The spatial distribution patterns of the elements analyzed show that traffic and industrial activities are the principal anthropogenic pollutant sources.

  19. Effect of action video games on the spatial distribution of visuospatial attention.

    Science.gov (United States)

    Green, C Shawn; Bavelier, Daphne

    2006-12-01

    The authors investigated the effect of action gaming on the spatial distribution of attention. The authors used the flanker compatibility effect to separately assess center and peripheral attentional resources in gamers versus nongamers. Gamers exhibited an enhancement in attentional resources compared with nongamers, not only in the periphery but also in central vision. The authors then used a target localization task to unambiguously establish that gaming enhances the spatial distribution of visual attention over a wide field of view. Gamers were more accurate than nongamers at all eccentricities tested, and the advantage held even when a concurrent center task was added, ruling out a trade-off between central and peripheral attention. By establishing the causal role of gaming through training studies, the authors demonstrate that action gaming enhances visuospatial attention throughout the visual field. (c) 2006 APA, all rights reserved.

  20. Tomographic radiotracer studies of the spatial distribution of heterogeneous geochemical transport processes

    International Nuclear Information System (INIS)

    Gruendig, Marion; Richter, Michael; Seese, Anita; Sabri, Osama

    2007-01-01

    Within the scope of the further development of geochemical transport models the consideration of the influence of the heterogeneous structures of the geological layers plays an important role. For the verification and parameter estimation of such models it is necessary to measure the heterogeneous transport and sorption processes inside the samples. Tomographic radiotracer methods (positron emission tomography (PET)) enable nondestructive spatially resolved observations of the transport processes in these layers. A special quantitative evaluation system for geoscientific PET studies was developed. Investigations of the water flow distribution in a drill core of a lignite mining dump and of the migration of Cu ions in a horizontal soil column illustrate the potential of this method. Spatial distribution functions of the flow velocity, the specific mass flow and the longitudinal dispersivity were determined on the basis of PET investigations

  1. Spatial Distribution of Tropospheric Ozone in National Parks of California: Interpretation of Passive-Sampler Data

    Directory of Open Access Journals (Sweden)

    John D. Ray

    2001-01-01

    Full Text Available The National Park Service (NPS has tested and used passive ozone samplers for several years to get baseline values for parks and to determine the spatial variability within parks. Experience has shown that the Ogawa passive samplers can provide ±10% accuracy when used with a quality assurance program consisting of blanks, duplicates, collocated instrumentation, and a standard operating procedure that carefully guides site operators. Although the passive device does not meet EPA criteria as a certified method (mainly, that hourly values be measured, it does provide seasonal summed values of ozone. The seasonal ozone concentrations from the passive devices can be compared to other monitoring to determine baseline values, trends, and spatial variations. This point is illustrated with some kriged interpolation maps of ozone statistics. Passive ozone samplers were used to get elevational gradients and spatial distributions of ozone within a park. This was done in varying degrees at Mount Rainier, Olympic, Sequoia–Kings Canyon, Yosemite, Joshua Tree, Rocky Mountain, and Great Smoky Mountains national parks. The ozone has been found to vary by factors of 2 and 3 within a park when average ozone is compared between locations. Specific examples of the spatial distributions of ozone in three parks within California are given using interpolation maps. Positive aspects and limitations of the passive sampling approach are presented.

  2. Spatial structure and distribution of small pelagic fish in the northwestern Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Claire Saraux

    Full Text Available Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean, sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than anchovies. The spatial structure of the three species was fairly stable over time according to variogram outputs, while year-to-year variations in kriged maps highlighted substantial changes in their location. Support for the McCall's basin hypothesis (covariation of both population density and presence area with biomass was found only in sprats, the most variable of the three species. An innovative method to investigate species collocation at different scales revealed that globally the three species strongly overlap. Although species often co-occurred in terms of presence/absence, their biomass density differed at local scale, suggesting potential interspecific avoidance or different sensitivity to local environmental characteristics. Persistent favourable areas were finally detected, but their environmental characteristics remain to be determined.

  3. Application of the Multitype Strauss Point Model for Characterizing the Spatial Distribution of Landslides

    Directory of Open Access Journals (Sweden)

    Iswar Das

    2016-01-01

    Full Text Available Landslides are common but complex natural hazards. They occur on the Earth’s surface following a mass movement process. This study applies the multitype Strauss point process model to analyze the spatial distributions of small and large landslides along with geoenvironmental covariates. It addresses landslides as a set of irregularly distributed point-type locations within a spatial region. Their intensity and spatial interactions are analyzed by means of the distance correlation functions, model fitting, and simulation. We use as a dataset the landslide occurrences for 28 years from a landslide prone road corridor in the Indian Himalayas. The landslides are investigated for their spatial character, that is, whether they show inhibition or occur as a regular or a clustered point pattern, and for their interaction with landslides in the neighbourhood. Results show that the covariates lithology, land cover, road buffer, drainage density, and terrain units significantly improved model fitting. A comparison of the output made with logistic regression model output showed a superior prediction performance for the multitype Strauss model. We compared results of this model with the multitype/hard core Strauss point process model that further improved the modeling. Results from the study can be used to generate landslide susceptibility scenarios. The paper concludes that a multitype Strauss point process model enriches the set of statistical tools that can comprehensively analyze landslide data.

  4. Spatial analysis of Neospora caninum distribution in dairy cattle from Sweden

    Directory of Open Access Journals (Sweden)

    Jenny Frössling

    2008-11-01

    Full Text Available The national herd prevalence and spatial distribution of Neospora caninum infected dairy herds in Sweden were investigated. The study was based on a bulk milk survey comprising samples from 2,978 herds. Test-positive herds were found in all parts of Sweden and the overall prevalence of test-positive herds was 8.3% (95% confidence interval = 7.3-9.3%. The presence of spatial autocorrelation was tested using the Moran’s I test. Possible clusters of test-positive herds were identified by applying the local indicator of spatial association (LISA test statistic and the spatial scan statistic. Analysis based on data aggregated by postal code areas as well as analysis based on exact coordinates identified significant clusters of high prevalence in the middle parts of Sweden and low prevalence in the south. This was not expected considering the results from other European studies of N. caninum in cattle. However, the findings are supported by the distribution of previously known case herds.

  5. Heterogeneous game resource distributions promote cooperation in spatial prisoner's dilemma game

    Science.gov (United States)

    Cui, Guang-Hai; Wang, Zhen; Yang, Yan-Cun; Tian, Sheng-Wen; Yue, Jun

    2018-01-01

    In social networks, individual abilities to establish interactions are always heterogeneous and independent of the number of topological neighbors. We here study the influence of heterogeneous distributions of abilities on the evolution of individual cooperation in the spatial prisoner's dilemma game. First, we introduced a prisoner's dilemma game, taking into account individual heterogeneous abilities to establish games, which are determined by the owned game resources. Second, we studied three types of game resource distributions that follow the power-law property. Simulation results show that the heterogeneous distribution of individual game resources can promote cooperation effectively, and the heterogeneous level of resource distributions has a positive influence on the maintenance of cooperation. Extensive analysis shows that cooperators with large resource capacities can foster cooperator clusters around themselves. Furthermore, when the temptation to defect is high, cooperator clusters in which the central pure cooperators have larger game resource capacities are more stable than other cooperator clusters.

  6. Evaluate the Spatial Distribution of ICT Indicators in Fourteen Areas of Isfahan Municipality

    Directory of Open Access Journals (Sweden)

    Ahmad Shahivandi

    2012-10-01

    Full Text Available Today, one of the criteria for the assessment of development of countries, international organizations and world economy is the achievement of the level of ICT. In addition, a fair distribution of this tool for better and update services is very important. The purpose of this study was to assess the spatial distribution parameters and hardware experts in the areas of ICT and informatics users fourteen municipality of Isfahan. Descriptive research method was analytic and for ranking, grading and determination of distribution models, statistical indicators Mac Granahan, cluster analysis and factor differences were used. The results showed that the different regions of Isfahan Municipality of enjoyment of these indicators were not equal to. Generally, these areas formed four classes to enjoy, have relatively less ill, have enjoyed and have been classified. The scattering coefficient showed large differences in the type and distribution of these indices in Isfahan Municipality there..

  7. Spatial distribution of cavitation-shock-pressure around a jet-flow gate-valve

    International Nuclear Information System (INIS)

    Oba, Risaburo; Takayama, Kazuyoshi; Ito, Yukio; Miyakura, Hideto; Nozaki, Satoru; Ishige, Tadashi; Sonoda, Shuji; Sakamoto, Kenji.

    1987-01-01

    To make clear the mechanism of cavitation erosion, the spatial distribution of cavitation shock pressures were quantitatively measured by a pressure sensitive sheet in the 1/10 scale model of a jet-flow gate-valve, for various valve-openings and cavitation numbers. The dynamic pressure response of the sheet was corrected by the shock wave generated from detonation explosives. It is made clear that the erosive shock pressures are distributed in a limited part of the whole cavitation region, and the safety region without the fatal cavitation erosion is defined. (author)

  8. Review and possible development direction of the methods for modeling of soil pollutants spatial distribution

    Science.gov (United States)

    Tarasov, D. A.; Medvedev, A. N.; Sergeev, A. P.; Buevich, A. G.

    2017-07-01

    Forecasting of environmental pollutants spatial distribution is a significant field of research in view of the current concerns regarding environment all over the world. Due to the danger to health and environment associated with an increase in pollution of air, soil, water and biosphere, it is very important to have the models that are capable to describe the modern distribution of contaminants and to forecast the dynamic of their spreading in future at different territories. This article addresses the methods, which applied the most often in this field, with an accent on soil pollution. The possible direction of such methods further development is suggested.

  9. Optimal wind energy penetration in power systems: An approach based on spatial distribution of wind speed

    International Nuclear Information System (INIS)

    Zolfaghari, Saeed; Riahy, Gholam H.; Abedi, Mehrdad; Golshannavaz, Sajjad

    2016-01-01

    Highlights: • Chronological wind speeds at distinct locations of the wind farm are not the same. • Spatial distribution of wind speed affects wind farm’s output power expectation. • Neglecting wind speed’s spatial doubt leads to mistake in wind energy penetration. • Scenario-based method can be used for effective wind capacity penetration level. - Abstract: Contributing in power system expansions, the present study establishes an efficient scheme for optimal integration of wind energy resources. The proposed approach highly concerns the spatial distribution of wind speed at different points of a wind farm. In mathematical statements, a suitable probability distribution function (PDF) is well-designed for representing such uncertainties. In such conditions, it is likely to have dissimilar output powers for individual and identical wind turbines. Thus, the overall aggregated PDF of a wind farm remarkably influences the critical parameters including the expected power and energy, capacity factor, and the reliability metrics such as loss of load expectation (LOLE) and expected energy not supplied (EENS). Furthermore, the proposed approach is deployed for optimal allocation of wind energy in bulk power systems. Hence, two typical test systems are numerically analyzed to interrogate the performance of the proposed approach. The conducted survey discloses an over/underestimation of harvestable wind energy in the case of overlooking spatial distributions. Thus, inaccurate amounts of wind farm’s capacity factor, output power, energy and reliability indices might be estimated. Meanwhile, the number of wind turbines may be misjudged to be installed. However, the proposed approach yields in a fair judgment regarding the overall performance of the wind farm. Consequently, a reliable penetration level of wind energy to the power system is assured. Extra discussions are provided to deeply assess the promising merits of the founded approach.

  10. Quantum key distribution with higher-order alphabets using spatially-encoded qudits

    OpenAIRE

    Walborn, S. P.; Lemelle, D. S.; Almeida, M. P.; Ribeiro, P. H. Souto

    2005-01-01

    We propose and demonstrate a quantum key distribution scheme in higher-order $d$-dimensional alphabets using spatial degrees of freedom of photons. Our implementation allows for the transmission of 4.56 bits per sifted photon, while providing improved security: an intercept-resend attack on all photons would induce an error rate of 0.47. Using our system, it should be possible to send more than a byte of information per sifted photon.

  11. The spatial distribution of pet dogs and pet cats on the island of Ireland.

    Science.gov (United States)

    Downes, Martin J; Clegg, Tracy A; Collins, Daniel M; McGrath, Guy; More, Simon J

    2011-06-10

    There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland. In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas. The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care.

  12. Stochastic analysis to assess the spatial distribution of groundwater nitrate concentrations in the Po catchment (Italy)

    International Nuclear Information System (INIS)

    Cinnirella, Sergio; Buttafuoco, Gabriele; Pirrone, Nicola

    2005-01-01

    A large database including temporal trends of physical, ecological and socio-economic data was developed within the EUROCAT project. The aim was to estimate the nutrient fluxes for different socio-economic scenarios at catchment and coastal zone level of the Po catchment (Northern Italy) with reference to the Water Quality Objectives reported in the Water Framework Directive (WFD 2000/60/CE) and also in Italian legislation. Emission data derived from different sources at national, regional and local levels are referred to point and non-point sources. While non-point (diffuse) sources are simply integrated into the nutrient flux model, point sources are irregularly distributed. Intensive farming activity in the Po valley is one of the main Pressure factors Driving groundwater pollution in the catchment, therefore understanding the spatial variability of groundwater nitrate concentrations is a critical issue to be considered in developing a Water Quality Management Plan. In order to use the scattered point source data as input in our biogeochemical and transport models, it was necessary to predict their values and associated uncertainty at unsampled locations. This study reports the spatial distribution and uncertainty of groundwater nitrate concentration at a test site of the Po watershed using a probabilistic approach. Our approach was based on geostatistical sequential Gaussian simulation used to yield a series of stochastic images characterized by equally probable spatial distributions of the nitrate concentration across the area. Post-processing of many simulations allowed the mapping of contaminated and uncontaminated areas and provided a model for the uncertainty in the spatial distribution of nitrate concentrations. - The stochastic simulation should be preferred to kriging in environmental studies, whenever it is critical to preserve the variation of a variable

  13. Difet: Distributed Feature Extraction Tool for High Spatial Resolution Remote Sensing Images

    Science.gov (United States)

    Eken, S.; Aydın, E.; Sayar, A.

    2017-11-01

    In this paper, we propose distributed feature extraction tool from high spatial resolution remote sensing images. Tool is based on Apache Hadoop framework and Hadoop Image Processing Interface. Two corner detection (Harris and Shi-Tomasi) algorithms and five feature descriptors (SIFT, SURF, FAST, BRIEF, and ORB) are considered. Robustness of the tool in the task of feature extraction from LandSat-8 imageries are evaluated in terms of horizontal scalability.

  14. Nuclear microprobe measurement of the spatial distribution on non-metals in metals

    International Nuclear Information System (INIS)

    McMillan, J.W.

    1981-01-01

    The spatial distributions of many non-metallic light elements and isotopes have been measured in metals by nuclear microprobe analysis, particularly through using nuclear reactions. In this paper, typical equipment and analysis techniques are briefly described. Applications are outlined, as is the range of elements that have been determined. Also, the advantages of nuclear microprobe methods are indicated, such as, their ability to discriminate against surface contamination, and their ability to measure isotopes. (orig./RB) [de

  15. DIFET: DISTRIBUTED FEATURE EXTRACTION TOOL FOR HIGH SPATIAL RESOLUTION REMOTE SENSING IMAGES

    Directory of Open Access Journals (Sweden)

    S. Eken

    2017-11-01

    Full Text Available In this paper, we propose distributed feature extraction tool from high spatial resolution remote sensing images. Tool is based on Apache Hadoop framework and Hadoop Image Processing Interface. Two corner detection (Harris and Shi-Tomasi algorithms and five feature descriptors (SIFT, SURF, FAST, BRIEF, and ORB are considered. Robustness of the tool in the task of feature extraction from LandSat-8 imageries are evaluated in terms of horizontal scalability.

  16. Land Use Influencing the Spatial Distribution of Urban Crime: A Case Study of Szczecin, Poland

    OpenAIRE

    Natalia Sypion-Dutkowska; Michael Leitner

    2017-01-01

    This paper falls into a common field of scientific research and its practical applications at the interface of urban geography, environmental criminology, and Geographic Information Systems (GIS). The purpose of this study is to identify types of different land use which influence the spatial distribution of a set of crime types at the intra-urban scale. The originality of the adopted approach lies in its consideration of a large number of different land use types considered as hypothetically...

  17. The spatial distribution of pet dogs and pet cats on the island of Ireland

    Science.gov (United States)

    2011-01-01

    Background There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland. Results In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas. Conclusions The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care. PMID:21663606

  18. The spatial distribution of pet dogs and pet cats on the island of Ireland

    Directory of Open Access Journals (Sweden)

    More Simon J

    2011-06-01

    Full Text Available Abstract Background There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland. Results In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas. Conclusions The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care.

  19. The spatial distribution of pet dogs and pet cats on the island of Ireland

    OpenAIRE

    Downes, Martin J.; Clegg, Tracy A.; Collins, Daniel M.; et al.

    2011-01-01

    Abstract Background There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This...

  20. Spatial Distributions of Tropical Cyclone Tornadoes by Intensity and Size Characteristics

    OpenAIRE

    Todd W. Moore; Nicholas J. Sokol; Robert A. Blume

    2017-01-01

    Tropical cyclones that make landfall often spawn tornadoes. Previous studies have shown that these tornadoes are not uniformly distributed in the United States or in the tropical cyclone environment. They show that tornadoes tend to occur relatively close to the coastline and that they tend to cluster to the east-of-center in the tropical cyclone environment, particularly in the northeast and east-of-center quadrants. This study contributes to these studies by analyzing the spatial distributi...

  1. Effects of density and hunger on the spatial distribution and pit ...

    African Journals Online (AJOL)

    The effects of hunger and density on the spatial distribution and pit construction by the larvae were studied for the three instar stages in fine and coarse sand textures of particles size of <540 μm and <1200 μm respectively.Twenty four (24) Iron trays of 25cm2 each filled with sand to the depth of 20cm were used in the study.

  2. The use of a Bonner sphere spectrometer for determining the spatial distribution of neutron fields

    CERN Document Server

    Varela, A; Jimenez, F; Calvillo, J

    1999-01-01

    The directional properties of a modified Bonner-type spectrometer, using spheres with a radial hole, are described in this report. It was found that spheres with these modifications are able to detect the spatial distribution of a neutron field. The neutrons were generated by the sup 9 Be(d,n) sup 1 sup 0 B reaction, produced by bombarding a thick Be target with 4 MeV deutrons provided by a tandem Van de Graaff accelerator.

  3. The Not So Simple Globular Cluster ω Cen. I. Spatial Distribution of the Multiple Stellar Populations

    Energy Technology Data Exchange (ETDEWEB)

    Calamida, A.; Saha, A. [National Optical Astronomy Observatory—AURA, 950 N Cherry Avenue, Tucson, AZ, 85719 (United States); Strampelli, G.; Rest, A. [Space Telescope Science Institute—AURA, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bono, G.; Ferraro, I.; Iannicola, G. [INAF—Osservatorio Astronomico di Roma—Via Frascati 33, I-00040, Monteporzio Catone, Rome (Italy); Scolnic, D. [The University of Chicago, The Kavli Institute for Cosmological Physics, William Eckhardt Research Center—Suite 499, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); James, D.; Smith, C.; Zenteno, A., E-mail: calamida@noao.edu [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)

    2017-04-01

    We present a multi-band photometric catalog of ≈1.7 million cluster members for a field of view of ≈2° × 2° across ω Cen. Photometry is based on images collected with the Dark Energy Camera on the 4 m Blanco telescope and the Advanced Camera for Surveys on the Hubble Space Telescope . The unprecedented photometric accuracy and field coverage allowed us, for the first time, to investigate the spatial distribution of ω Cen multiple populations from the core to the tidal radius, confirming its very complex structure. We found that the frequency of blue main-sequence stars is increasing compared to red main-sequence stars starting from a distance of ≈25′ from the cluster center. Blue main-sequence stars also show a clumpy spatial distribution, with an excess in the northeast quadrant of the cluster pointing toward the direction of the Galactic center. Stars belonging to the reddest and faintest red-giant branch also show a more extended spatial distribution in the outskirts of ω Cen, a region never explored before. Both these stellar sub-populations, according to spectroscopic measurements, are more metal-rich compared to the cluster main stellar population. These findings, once confirmed, make ω Cen the only stellar system currently known where metal-rich stars have a more extended spatial distribution compared to metal-poor stars. Kinematic and chemical abundance measurements are now needed for stars in the external regions of ω Cen to better characterize the properties of these sub-populations.

  4. Spatial and kinematic distributions of transition populations in intermediate redshift galaxy clusters

    International Nuclear Information System (INIS)

    Crawford, Steven M.; Wirth, Gregory D.; Bershady, Matthew A.

    2014-01-01

    We analyze the spatial and velocity distributions of confirmed members in five massive clusters of galaxies at intermediate redshift (0.5 < z < 0.9) to investigate the physical processes driving galaxy evolution. Based on spectral classifications derived from broad- and narrow-band photometry, we define four distinct galaxy populations representing different evolutionary stages: red sequence (RS) galaxies, blue cloud (BC) galaxies, green valley (GV) galaxies, and luminous compact blue galaxies (LCBGs). For each galaxy class, we derive the projected spatial and velocity distribution and characterize the degree of subclustering. We find that RS, BC, and GV galaxies in these clusters have similar velocity distributions, but that BC and GV galaxies tend to avoid the core of the two z ≈ 0.55 clusters. GV galaxies exhibit subclustering properties similar to RS galaxies, but their radial velocity distribution is significantly platykurtic compared to the RS galaxies. The absence of GV galaxies in the cluster cores may explain their somewhat prolonged star-formation history. The LCBGs appear to have recently fallen into the cluster based on their larger velocity dispersion, absence from the cores of the clusters, and different radial velocity distribution than the RS galaxies. Both LCBG and BC galaxies show a high degree of subclustering on the smallest scales, leading us to conclude that star formation is likely triggered by galaxy-galaxy interactions during infall into the cluster.

  5. Temporal and spatial variations of water qualities and fish fauna distributions in the Kaname river, Japan

    Science.gov (United States)

    Terada, K.; Kitano, T.; Kutsumi, M.; Shimizu, K.

    2011-12-01

    Fish fauna distributions had been studied at many places and they indicated that the fish distributions were dramatically different depending on fish species and local environment such as water temperature, current, sediment parameters. But the relationships between water qualities and fish fauna distribution have not been understood well. In order to find physical and chemical environment factors which relate to the fish fauna distribution, we investigated the temporal and spatial change of water qualities and fish distributions in Kaname river, Japan. We measured both of physical (temperature, salinity, dissolved oxygen, Chl-a and turbidity) and chemical (nitrate, nitrite, ammonia, orthophosphoric and suspended solids) water parameters and surveyed the fish distribution. The field observations were conducted seasonally and check the season differences. Observation results showed that Gobiidae and Cyprinidae fishes live in the Kaname river and the distribution was clearly classified with the species. And also chemical water qualities were dramatically different by location. Especially the effects of sewage farms on water qualities were detected. This study will be contributory to reveal the relationships between fish fauna distribution and environmental parameters and it will lead to the ecological preservation.

  6. Spatial patterns of mesozooplankton communities in the Northwestern Iberian shelf during autumn shaped by key environmental factors

    Science.gov (United States)

    Domínguez, Rula; Garrido, Susana; Santos, A. Miguel P.; dos Santos, Antonina

    2017-11-01

    The autumn mesozooplankton community structure and spatial distribution was investigated in relation to the prevalent hydrographic conditions at the Northwestern Iberian shelf (38.5°-41.6°N), a major spawning ground for small pelagic fish species. Copepods clearly dominated the mesozooplankton community, followed by Cladocera, Appendicularia, Cirripedia, Bivalvia larvae and Chaetognata. Three different groups were identified according to their distribution: a northern coastal group (A), a southern coastal group with two stations in the northern area (B), and a shelf group (C), each delimited to areas with distinct oceanographic conditions. The boundary between the coastal groups A and B was coincident with areas of prominent geographic features, particularly a submarine canyon (Nazaré canyon) and a cape (Cabo Carvoeiro), both inducing abrupt changes in the local/regional patterns of water mass circulation. Group B includes a few northern stations that can be related to river discharges while the southern stations can be defined by upwelling conditions at that time. The distribution of some relevant species can be related to biophysical variables (temperature, salinity, Chlorophyll a). Some copepod taxa were generally coincident with high concentrations of chlorophyll a abundance (e.g. Temora spp., Oncaea spp.), while the distribution of other groups such as Cladocera or bivalve veliger larvae was correlated to temperature and/or salinity gradients caused by river discharges. Other important taxa as Paracalanus and Clausocalanus spp. or Oithona spp. showed no particular influence of any of the measured hydrological variables. This work is the first description of mesozooplankton assemblages and their distribution pattern in a broad area off Western Iberia during autumn. It contributes to understanding the dynamics of zooplankton in the area, increasing the knowledge of the drivers of plankton community variability and providing information about their potential

  7. Measurement of spatial dose distribution for evaluation operator dose during nero-interventional procedures

    Energy Technology Data Exchange (ETDEWEB)

    Han, Su Chul [Division of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Hong, Dong Hee [Dept. of Radiology Science, Far East University, Eumseong (Korea, Republic of)

    2016-09-15

    The spatial dose distribution was measured with ionization chamber as preliminary study to evaluate operator dose and to study dose reduction during neuro-interventional procedures. The zone of operators was divided into four area (45, 135, 225, and 315 degree).We supposed that operator exist on the four area and indicated location of critical organs(eyes, breast, gonad). The spatial doses were measured depending on distance( 80, 100, 120, and 140 cm) and location of critical organs. The spatial doses of area of 225 degree were 114.5 mR/h (eyes location), 143.1 mR/h (breast location) and 147 mR/h (gonad location) in 80 cm. When changed location of x-ray generator, spatial dose increased in 18.1±10.5%, averagely. We certified spatial dose in the operator locations, Using the results of this study, It is feasible to protect operator from radiation in neuro-interventional procedures.

  8. The effect of the egg's shape on the stress distribution in the eggshell at internal pressure loading

    Directory of Open Access Journals (Sweden)

    Šárka Nedomová

    2007-01-01

    Full Text Available The influence of the eggshell shape on the stress distribution under internal pressure is studied. A mathematical description of the hen's eggshell is proposed. The analytical expressions for the membrane solution are presented. Obtained results are used for the evaluation of a set of domestic hen's eggs. 28 eggs were analysed in this study. The weight of eggs ranged from 49.55 g to 61.08 g, the egg shape ranged from 72.82 % to 84.94 %, the average eggshell thickness ranged from 0.343 to 0.433 mm. The eggshell strength is given namely by the maximum values both of meridian and circumferential forces. The dependence of the meridian force maximum on the egg shape index has some tendency to increase with egg shape index. The outlined linear dependence is very weak, the coefficient of correlation is about 0.45.

  9. Habitat modeling for cetacean management: Spatial distribution in the southern Pelagos Sanctuary (Mediterranean Sea)

    Science.gov (United States)

    Pennino, Maria Grazia; Mérigot, Bastien; Fonseca, Vinícius Prado; Monni, Virginia; Rotta, Andrea

    2017-07-01

    Effective management and conservation of wild populations requires knowledge of their habitats, especially by mean of quantitative analyses of their spatial distributions. The Pelagos Sanctuary is a dedicated marine protected area for Mediterranean marine mammals covering an area of 90,000 km2 in the north-western Mediterranean Sea between Italy, France and the Principate of Monaco. In the south of the Sanctuary, i.e. along the Sardinian coast, a range of diverse human activities (cities, industry, fishery, tourism) exerts several current ad potential threats to cetacean populations. In addition, marine mammals are recognized by the EU Marine Strategy Framework Directive as essential components of sustainable ecosystems. Yet, knowledge on the spatial distribution and ecology of cetaceans in this area is quite scarce. Here we modeled occurrence of the three most abundant species known in the Sanctuary, i.e. the striped dolphin (Stenella coeruleoalba), the bottlenose dolphin (Tursiops truncatus) and the fin whales (Balaenoptera physalus), using sighting data from scientific surveys collected from 2012 to 2014 during summer time. Bayesian site-occupancy models were used to model their spatial distribution in relation to habitat taking into account oceanographic (sea surface temperature, primary production, photosynthetically active radiation, chlorophyll-a concentration) and topographic (depth, slope, distance of the land) variables. Cetaceans responded differently to the habitat features, with higher occurrence predicted in the more productive areas on submarine canyons. These results provide ecological information useful to enhance management plans and establish baseline for future population trend studies.

  10. Predicting the spatial distribution of Biomphalaria straminea, a potential intermediate host for Schistosoma mansoni, in China

    Directory of Open Access Journals (Sweden)

    Mohamed R. Habib

    2016-11-01

    Full Text Available Schistosomiasis is one of the most prevalent parasitic diseases impacting human health in the tropics and sub-tropics. The geographic distribution of Schistosoma mansoni, the most widespread species, includes areas in Africa, the Middle East, South America and the Caribbean. Snails of the genus Biomphalaria act as intermediate host for S. mansoni. Biomphalaria straminea is not indigenous in China but was accidentally introduced to Hong Kong from South America and has spread to other habitats in the southern parts of the country. This species is known for its great dispersal capacity that highlights the importance of the snail as a potential host for S. mansoni in China. In this connection, although no such infection has been recorded in the field so far, the continuous expansion of China’s projects in endemic areas of Africa and import of the infection via returning workers or visitors deserve attention. The purpose of this study was to map and predict the spatial distribution of B. straminea in China. Snail occurrence data were assembled and investigated using MaxEnt software, along with climatic and environmental variables to produce a predictive risk map. Of the environmental variables tested, the precipitation of warmest quarter was the most contribution factor for snail’s spatial distribution. Risk areas were found in southeastern China and it is expected that they will guide policies and control programmes to potential areas area of snail abundance and used for spatial targeting of control interventions for this invasive species.

  11. Spatial distribution and cluster analysis of sexual risk behaviors reported by young men in Kisumu, Kenya

    Directory of Open Access Journals (Sweden)

    Parker Corette

    2010-05-01

    Full Text Available Abstract Background The well-established connection between HIV risk behavior and place of residence points to the importance of geographic clustering in the potential transmission of HIV and other sexually transmitted infections (STI. Methods To investigate the geospatial distribution of prevalent sexually transmitted infections and sexual behaviors in a sample of 18-24 year-old sexually active men in urban and rural areas of Kisumu, Kenya, we mapped the residences of 649 men and conducted spatial cluster analysis. Spatial distribution of the study participants was assessed in terms of the demographic, behavioral, and sexual dysfunction variables, as well as laboratory diagnosed STIs. To test for the presence and location of clusters we used Kulldorff's spatial scan statistic as implemented in the Satscan program. Results The results of this study suggest that sexual risk behaviors and STIs are evenly distributed in our sample throughout the Kisumu district. No behavioral or STI clusters were detected, except for condom use. Neither urban nor rural residence significantly impacted risk behavior or STI prevalence. Conclusion We found no association between place of residence and sexual risk behaviors in our sample. While our results can not be generalized to other populations, the study shows that geospatial analysis can be an important tool for investigating study sample characteristics; for evaluating HIV/STI risk factors; and for development and implementation of targeted HIV and STI control programs in specifically defined populations and in areas where the underlying population dynamic is poorly understood.

  12. Analysis of spatial distribution of Tehran Metropolis urban services using models of urban planning

    Directory of Open Access Journals (Sweden)

    A. Lorestani

    2016-04-01

    Full Text Available The process of spatial distribution of urban services in order to provide equitable access to opportunities and reduced regional disparities, and earning the highest citizen satisfaction are among the main challenges facing urban management. This requires knowledge of the current status of spatial distribution of public services in the city, followed by optimal resource allocation under varying circumstances. This analytical-comparative study aimed to investigate the spatial distribution of urban public services, and rank different districts of Tehran in terms of benefiting from public services. To achieve this goal, quantitative models of planning, including factor analysis, composite Human Development Index, taxonomical model and standardization method were used. For the final ranking of districts of Tehran, the sum of numerical value of each district was calculated in four ways. Based on this method, districts 1, 3, 22, 12 and 6 were ranked first to fifth, and districts 13, 10, 8, 17 and 14 were ranked last, respectively. Using cluster analysis model, different districts of Tehran metropolis were clustered on the basis of numerical value of districts in the models used. Based on above-mentioned results, districts 1, 3, 12, 22, 6 and 21, with a final score of 66 and above, included in the first cluster and identified as over-developed districts; and districts 14, 10, 8 and 17, with a final score of 13 or less, included in the fifth cluster and identified as disadvantaged districts.

  13. Integration of GIS, Geostatistics, and 3-D Technology to Assess the Spatial Distribution of Soil Moisture

    Science.gov (United States)

    Betts, M.; Tsegaye, T.; Tadesse, W.; Coleman, T. L.; Fahsi, A.

    1998-01-01

    The spatial and temporal distribution of near surface soil moisture is of fundamental importance to many physical, biological, biogeochemical, and hydrological processes. However, knowledge of these space-time dynamics and the processes which control them remains unclear. The integration of geographic information systems (GIS) and geostatistics together promise a simple mechanism to evaluate and display the spatial and temporal distribution of this vital hydrologic and physical variable. Therefore, this research demonstrates the use of geostatistics and GIS to predict and display soil moisture distribution under vegetated and non-vegetated plots. The research was conducted at the Winfred Thomas Agricultural Experiment Station (WTAES), Hazel Green, Alabama. Soil moisture measurement were done on a 10 by 10 m grid from tall fescue grass (GR), alfalfa (AA), bare rough (BR), and bare smooth (BS) plots. Results indicated that variance associated with soil moisture was higher for vegetated plots than non-vegetated plots. The presence of vegetation in general contributed to the spatial variability of soil moisture. Integration of geostatistics and GIS can improve the productivity of farm lands and the precision of farming.

  14. [Spatial distribution of fig wasps in syconia of two monoecious Ficus sp].

    Science.gov (United States)

    Wang, Zhen-Ji; Li, Guo-Chang; Peng, Yan-Qiong; Yang, Da-Rong

    2012-04-01

    In addition to pollinator fig wasps, there are several non-pollinating fig wasps associated with monoecious Ficus sp. In order to understand how pollinator fig wasps and non-pollinating fig wasps are distributed across the same syconium, the spatial distribution of fig wasps associated with Ficus altissima and F. benjamina were compared using the pedicle lengths of galls containing each species. The results indicate that in Ficus altissima, the average pedicel length of galls containing Eupristina sp. is longer than that containing E. altissima. Average pedicel length of galls containing Sycobia sp., Micranisa ralianga and Sycoscapter sp. two did not show significant difference. The range of pedicel lengths of galls containing Sycobia sp., M. ralianga or Sycoscapter sp. two is narrower than that of galls containing E. altissima, indicating these non-pollinating fig wasps and pollinator have partially separated spatial niches. In F. benjamina, E. koningsbergeri was distributed in galls from the outer layer to inner layer, while most Walkerella sp. were found in outer layer galls, indicating E. koningsbergeri and Walkerella sp. have partially separated spatial niches.

  15. Spatial distribution of malaria in Peninsular Malaysia from 2000 to 2009.

    Science.gov (United States)

    Alias, Haridah; Surin, Johari; Mahmud, Rohela; Shafie, Aziz; Mohd Zin, Junaidden; Mohamad Nor, Mahadzir; Ibrahim, Ahmad Shah; Rundi, Christina

    2014-04-15

    Malaria is still an endemic disease of public health importance in Malaysia. Populations at risk of contracting malaria includes indigenous people, traditional villagers, mobile ethnic groups and land scheme settlers, immigrants from malaria endemic countries as well as jungle workers and loggers. The predominant species are Plasmodium falciparum and P. vivax. An increasing number of P. knowlesi infections have also been encountered. The principal vectors in Peninsular Malaysia are Anopheles maculatus and An. cracens. This study aims to determine the changes in spatial distribution of malaria in Peninsular Malaysia from year 2000-2009. Data for the study was collected from Ministry of Health, Malaysia and was analysed using Geographic Information System (GIS). Changes for a period of 10 years of malaria spatial distribution in 12 states of Peninsular Malaysia were documented and discussed. This is illustrated by digital mapping according to five variables; incidence rate (IR), fatality rate (FR), annual blood examination rate (ABER), annual parasite index (API) and slide positivity rate (SPR). There is a profound change in the spatial distribution of malaria within a 10-year period. This is evident from the digital mapping of the infection in Peninsular Malaysia.

  16. The Spatial Distribution of Volcanic Events on Io in 2013-2015

    Science.gov (United States)

    de Kleer, Katherine R.; de Pater, Imke

    2015-11-01

    The spatial distribution of heat flow on Io is a key prediction of tidal heat dissipation models, and therefore provides an important constraint for understanding Io’s interior. However, the majority of our knowledge about eruption locations is derived from geological features tracing long time periods (e.g. Hamilton et al., 2013), and from activity during the Galileo era (e.g. Davies et al., 2015; Veeder et al., 2015).We report on new results from a campaign to image Io in the near-infrared with adaptive optics on the Keck and Gemini N telescopes. We observed Io on 93 nights between August 2013 and June 2015, detecting volcanic activity at dozens of hot spot locations. We present the spatial distribution of the observed eruption sites during this period, and compare this with the distributions inferred from past hot spot and patera locations by previous authors. We discuss the locations of eruptions of different magnitudes, including a preponderance of bright activity at latitudes polewards of 45 degrees in both hemispheres and an apparent spatial clustering of activity in the months following large eruptions. Finally, we address the durations of the detected eruptions, as well as connecting our findings to the EXCEED Mission’s observations of the Io plasma torus during the same time period.

  17. Modeling of the spatial distribution of ten endangered bird species in jurisdiction of Corantioquia

    International Nuclear Information System (INIS)

    Gomez M, Ana Maria; Alvarez, Esteban

    2006-01-01

    Recently, thanks to advances made in Geographic Information Systems (GIS), techniques have been developed for the construction of models that predict the spatial distribution of species and other attributes of biodiversity. These methods have allowed for the development of objective criteria that are fundamental for making decisions regarding the creation of protected areas systems throughout the world. In this research, the spatial distribution of ten endangered species of birds found within the jurisdiction of CORANTIOQUIA (JDC from here on) was modelled, using GIS techniques. The JDC was divided into 177 squares of 15 x 10 Km and the following variables were quantified within each one: presence or absence of endangered species of birds, rainfall, temperature, sun brightness, relative humidity, day duration, altitude, vegetal cover, slope and primary net productivity. With the help of logistic regression were made predictive models. Based on logistic regressions techniques predictive models were made. These models allow to explain a percentage between 24% and 80% of spatial distribution variability of these species. Those results can help in the identification of valuable zones for the biodiversity conservation. In places where there are neither the time or the economic resources to carry out exhaustive analyses of biodiversity, the models can predict the probable presence of this endangered species

  18. Improvement in the Spatial Distribution of Pain, Somatic Symptoms, and Depression After a Weight Loss Intervention.

    Science.gov (United States)

    Schrepf, Andrew; Harte, Steven E; Miller, Nicole; Fowler, Christine; Nay, Catherine; Williams, David A; Clauw, Daniel J; Rothberg, Amy

    2017-12-01

    Weight loss is known to improve pain localized to weight-bearing joints but it is not known how weight loss affects the spatial distribution of pain and associated somatic symptoms like fatigue. We sought to determine if weight loss using a low-calorie diet improves pain, affect, and somatic symptoms commonly associated with chronic pain conditions in an observational study. We also documented changes in inflammatory markers in serum before and after weight loss. Participants were 123 obese individuals undergoing a 12- to 16-week calorie restriction weight loss intervention. The spatial distribution of pain, symptom severity (eg, fatigue, sleep difficulties), depression, and total fibromyalgia scale scores were measured before and after weight loss. Pain (P = . 022), symptom severity (P = .004), depression (P weight loss; men showed greater improvement than women on somatic symptoms and fibromyalgia scores (both P weight showed greater improvement than those who lost Weight loss may improve diffuse pain and comorbid symptoms commonly seen in chronic pain participants. This article presents the effect of a weight loss intervention on characteristics of chronic pain, including the spatial distribution of pain and comorbid somatic symptoms. Weight loss appeared to produce larger improvements in somatic symptoms for men. Copyright © 2017 The American Pain Society. Published by Elsevier Inc. All rights reserved.

  19. Unpreferred plants affect patch choice and spatial distribution of European brown hares

    Science.gov (United States)

    Kuijper, D. P. J.; Bakker, J. P.

    2008-11-01

    Many herbivore species prefer to forage on patches of intermediate biomass. Plant quality and forage efficiency are predicted to decrease with increasing plant standing crop which explains the lower preference of the herbivore. However, often is ignored that on the long-term, plant species composition is predicted to change with increasing plant standing crop. The amount of low-quality, unpreferred food plants increases with increasing plant standing crop. In the present study the effects of unpreferred plants on patch choice and distribution of European brown hare in a salt-marsh system were studied. In one experiment, unpreferred plants were removed from plots. In the second experiment, plots were planted with different densities of an unpreferred artificial plant. Removal of unpreferred plants increased hare-grazing pressure more than fivefold compared to unmanipulated plots. Planting of unpreferred plants reduced hare-grazing pressure, with a significant reduction of grazing already occurring at low unpreferred plant density. Spatial distribution of hares within this salt-marsh system was related to spatial arrangement of unpreferred plants. Hare-grazing intensity decreased strongly with increasing abundance of unpreferred plants despite a high abundance of principal food plants. The results of this study indicate that plant species replacement is an important factor determining patch choice and spatial distribution of hares next to changing plant quality. Increasing abundance of unpreferred plant species can strengthen the decreasing patch quality with increasing standing crop and can decrease grazing intensity when preferred food plants are still abundantly present.

  20. The spatial heterogeneity between Japanese encephalitis incidence distribution and environmental variables in Nepal.

    Directory of Open Access Journals (Sweden)

    Daniel E Impoinvil

    Full Text Available To identify potential environmental drivers of Japanese Encephalitis virus (JE transmission in Nepal, we conducted an ecological study to determine the spatial association between 2005 Nepal JE incidence, and climate, agricultural, and land-cover variables at district level.District-level data on JE cases were examined using Local Indicators of Spatial Association (LISA analysis to identify spatial clusters from 2004 to 2008 and 2005 data was used to fit a spatial lag regression model with climate, agriculture and land-cover variables.Prior to 2006, there was a single large cluster of JE cases located in the Far-West and Mid-West terai regions of Nepal. After 2005, the distribution of JE cases in Nepal shifted with clusters found in the central hill areas. JE incidence during the 2005 epidemic had a stronger association with May mean monthly temperature and April mean monthly total precipitation compared to mean annual temperature and precipitation. A parsimonious spatial lag regression model revealed, 1 a significant negative relationship between JE incidence and April precipitation, 2 a significant positive relationship between JE incidence and percentage of irrigated land 3 a non-significant negative relationship between JE incidence and percentage of grassland cover, and 4 a unimodal non-significant relationship between JE Incidence and pig-to-human ratio.JE cases clustered in the terai prior to 2006 where it seemed to shift to the Kathmandu region in subsequent years. The spatial pattern of JE cases during the 2005 epidemic in Nepal was significantly associated with low precipitation and the percentage of irrigated land. Despite the availability of an effective vaccine, it is still important to understand environmental drivers of JEV transmission since the enzootic cycle of JEV transmission is not likely to be totally interrupted. Understanding the spatial dynamics of JE risk factors may be useful in providing important information to the