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. Spatial distribution

    DEFF Research Database (Denmark)

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

    2008-01-01

    , depending on the nature of intraspecific interactions between them: while the individuals of some species repel each other and partition the available area, others form groups of varying size, determined by the fitness of each group member. The spatial distribution pattern of individuals again strongly......Living organisms are distributed over the entire surface of the planet. The distribution of the individuals of each species is not random; on the contrary, they are strongly dependent on the biology and ecology of the species, and vary over different spatial scale. The structure of whole...... 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...

  4. 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

  5. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    International Nuclear Information System (INIS)

    Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Komarov, V M; Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Charukhchev, A V; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Andreev, A A; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Platonov, K Yu

    2014-01-01

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10 18 W cm -2 . Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  6. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, V M; Charukhchev, A V [Public Limited Company " Scientific research Institute for Optoelectronic Instrument Engineering" , Leningrad region (Russian Federation); Andreev, A A; Platonov, K Yu [Federal State Unitary Enterprise All-Russian Scientific Center " S.I.Vavilov State Optical Institute" (FSUE GOI), St.Petersburg (Russian Federation)

    2014-12-31

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10{sup 18} W cm{sup -2}. Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  7. A new head phantom with realistic shape and spatially varying skull resistivity distribution.

    Science.gov (United States)

    Li, Jian-Bo; Tang, Chi; Dai, Meng; Liu, Geng; Shi, Xue-Tao; Yang, Bin; Xu, Can-Hua; Fu, Feng; You, Fu-Sheng; Tang, Meng-Xing; Dong, Xiu-Zhen

    2014-02-01

    Brain electrical impedance tomography (EIT) is an emerging method for monitoring brain injuries. To effectively evaluate brain EIT systems and reconstruction algorithms, we have developed a novel head phantom that features realistic anatomy and spatially varying skull resistivity. The head phantom was created with three layers, representing scalp, skull, and brain tissues. The fabrication process entailed 3-D printing of the anatomical geometry for mold creation followed by casting to ensure high geometrical precision and accuracy of the resistivity distribution. We evaluated the accuracy and stability of the phantom. Results showed that the head phantom achieved high geometric accuracy, accurate skull resistivity values, and good stability over time and in the frequency domain. Experimental impedance reconstructions performed using the head phantom and computer simulations were found to be consistent for the same perturbation object. In conclusion, this new phantom could provide a more accurate test platform for brain EIT research.

  8. 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.

  9. Spatial shape of avalanches

    Science.gov (United States)

    Zhu, Zhaoxuan; Wiese, Kay Jörg

    2017-12-01

    In disordered elastic systems, driven by displacing a parabolic confining potential adiabatically slowly, all advance of the system is in bursts, termed avalanches. Avalanches have a finite extension in time, which is much smaller than the waiting time between them. Avalanches also have a finite extension ℓ in space, i.e., only a part of the interface of size ℓ moves during an avalanche. Here we study their spatial shape 〈S(x ) 〉 ℓ given ℓ , as well as its fluctuations encoded in the second cumulant 〈S2(x ) 〉 ℓ c. We establish scaling relations governing the behavior close to the boundary. We then give analytic results for the Brownian force model, in which the microscopic disorder for each degree of freedom is a random walk. Finally, we confirm these results with numerical simulations. To do this properly we elucidate the influence of discretization effects, which also confirms the assumptions entering into the scaling ansatz. This allows us to reach the scaling limit already for avalanches of moderate size. We find excellent agreement for the universal shape and its fluctuations, including all amplitudes.

  10. Microscopic prediction of speech intelligibility in spatially distributed speech-shaped noise for normal-hearing listeners.

    Science.gov (United States)

    Geravanchizadeh, Masoud; Fallah, Ali

    2015-12-01

    A binaural and psychoacoustically motivated intelligibility model, based on a well-known monaural microscopic model is proposed. This model simulates a phoneme recognition task in the presence of spatially distributed speech-shaped noise in anechoic scenarios. In the proposed model, binaural advantage effects are considered by generating a feature vector for a dynamic-time-warping speech recognizer. This vector consists of three subvectors incorporating two monaural subvectors to model the better-ear hearing, and a binaural subvector to simulate the binaural unmasking effect. The binaural unit of the model is based on equalization-cancellation theory. This model operates blindly, which means separate recordings of speech and noise are not required for the predictions. Speech intelligibility tests were conducted with 12 normal hearing listeners by collecting speech reception thresholds (SRTs) in the presence of single and multiple sources of speech-shaped noise. The comparison of the model predictions with the measured binaural SRTs, and with the predictions of a macroscopic binaural model called extended equalization-cancellation, shows that this approach predicts the intelligibility in anechoic scenarios with good precision. The square of the correlation coefficient (r(2)) and the mean-absolute error between the model predictions and the measurements are 0.98 and 0.62 dB, respectively.

  11. 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...

  12. Spatial distribution of aquatic insects

    DEFF Research Database (Denmark)

    Iversen, Lars Lønsmann

    (time since glacial disturbance and habitat stability) and question the generality of these processes for the understanding of species richness gradients in European rivers. Using regional distributions of European mayflies, stoneflies, and caddisflies this chapter demonstrates that differences...... 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...

  13. 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.

  14. 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 that operates on the premise of shaping inputs—whose spatial distribution is fixed—by use of a model, such that these inputs, in one structural subdomain at a time, suppress certain steady-state vibration quantities (depending on the type of damage one seeks to interrogate for......). 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...

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. Spectral and spatial shaping of Smith-Purcell radiation

    Science.gov (United States)

    Remez, Roei; Shapira, Niv; Roques-Carmes, Charles; Tirole, Romain; Yang, Yi; Lereah, Yossi; Soljačić, Marin; Kaminer, Ido; Arie, Ady

    2017-12-01

    The Smith-Purcell effect, observed when an electron beam passes in the vicinity of a periodic structure, is a promising platform for the generation of electromagnetic radiation in previously unreachable spectral ranges. However, most of the studies of this radiation were performed on simple periodic gratings, whose radiation spectrum exhibits a single peak and its higher harmonics predicted by a well-established dispersion relation. Here, we propose a method to shape the spatial and spectral far-field distribution of the radiation using complex periodic and aperiodic gratings. We show, theoretically and experimentally, that engineering multiple peak spectra with controlled widths located at desired wavelengths is achievable using Smith-Purcell radiation. Our method opens the way to free-electron-driven sources with tailored angular and spectral responses, and gives rise to focusing functionality for spectral ranges where lenses are unavailable or inefficient.

  20. Spatial distributions of Cu polycrystal sputtered atoms

    International Nuclear Information System (INIS)

    Abgaryan, V.K.; Semenov, A.A.; Shkarban, I.I.

    2004-01-01

    The results of the experimental determination of the Cu atoms spatial distribution, sputtered from the polycrystalline copper target, irradiated by the Xe + ions with the energy of 300 eV, are presented. The spatial distributions of the sputtered particles, calculated through the quasistable-dynamic model of the cascade modeling (CAMO) are presented also for the case of the polycrystalline copper irradiation by the Ar + and Xe + ions with the energy of 300-1000 eV [ru

  1. 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

  2. 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).

  3. Spatially Distributed Social Complex Networks

    Directory of Open Access Journals (Sweden)

    Gerald F. Frasco

    2014-01-01

    Full Text Available We propose a bare-bones stochastic model that takes into account both the geographical distribution of people within a country and their complex network of connections. The model, which is designed to give rise to a scale-free network of social connections and to visually resemble the geographical spread seen in satellite pictures of the Earth at night, gives rise to a power-law distribution for the ranking of cities by population size (but for the largest cities and reflects the notion that highly connected individuals tend to live in highly populated areas. It also yields some interesting insights regarding Gibrat’s law for the rates of city growth (by population size, in partial support of the findings in a recent analysis of real data [Rozenfeld et al., Proc. Natl. Acad. Sci. U.S.A. 105, 18702 (2008.]. The model produces a nontrivial relation between city population and city population density and a superlinear relationship between social connectivity and city population, both of which seem quite in line with real data.

  4. Spatially Distributed Social Complex Networks

    Science.gov (United States)

    Frasco, Gerald F.; Sun, Jie; Rozenfeld, Hernán D.; ben-Avraham, Daniel

    2014-01-01

    We propose a bare-bones stochastic model that takes into account both the geographical distribution of people within a country and their complex network of connections. The model, which is designed to give rise to a scale-free network of social connections and to visually resemble the geographical spread seen in satellite pictures of the Earth at night, gives rise to a power-law distribution for the ranking of cities by population size (but for the largest cities) and reflects the notion that highly connected individuals tend to live in highly populated areas. It also yields some interesting insights regarding Gibrat's law for the rates of city growth (by population size), in partial support of the findings in a recent analysis of real data [Rozenfeld et al., Proc. Natl. Acad. Sci. U.S.A. 105, 18702 (2008).]. The model produces a nontrivial relation between city population and city population density and a superlinear relationship between social connectivity and city population, both of which seem quite in line with real data.

  5. 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.

  6. 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.

  7. 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.

  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. Scale and shape mixtures of multivariate skew-normal distributions

    KAUST Repository

    Arellano-Valle, Reinaldo B.; Ferreira, Clé cio S.; Genton, Marc G.

    2018-01-01

    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

  10. An Innovative Metric to Evaluate Satellite Precipitation's Spatial Distribution

    Science.gov (United States)

    Liu, H.; Chu, W.; Gao, X.; Sorooshian, S.

    2011-12-01

    Thanks to its capability to cover the mountains, where ground measurement instruments cannot reach, satellites provide a good means of estimating precipitation over mountainous regions. In regions with complex terrains, accurate information on high-resolution spatial distribution of precipitation is critical for many important issues, such as flood/landslide warning, reservoir operation, water system planning, etc. Therefore, in order to be useful in many practical applications, satellite precipitation products should possess high quality in characterizing spatial distribution. However, most existing validation metrics, which are based on point/grid comparison using simple statistics, cannot effectively measure satellite's skill of capturing the spatial patterns of precipitation fields. This deficiency results from the fact that point/grid-wised comparison does not take into account of the spatial coherence of precipitation fields. Furth more, another weakness of many metrics is that they can barely provide information on why satellite products perform well or poor. Motivated by our recent findings of the consistent spatial patterns of the precipitation field over the western U.S., we developed a new metric utilizing EOF analysis and Shannon entropy. The metric can be derived through two steps: 1) capture the dominant spatial patterns of precipitation fields from both satellite products and reference data through EOF analysis, and 2) compute the similarities between the corresponding dominant patterns using mutual information measurement defined with Shannon entropy. Instead of individual point/grid, the new metric treat the entire precipitation field simultaneously, naturally taking advantage of spatial dependence. Since the dominant spatial patterns are shaped by physical processes, the new metric can shed light on why satellite product can or cannot capture the spatial patterns. For demonstration, a experiment was carried out to evaluate a satellite

  11. Membrane shape modulates transmembrane protein distribution.

    Science.gov (United States)

    Aimon, Sophie; Callan-Jones, Andrew; Berthaud, Alice; Pinot, Mathieu; Toombes, Gilman E S; Bassereau, Patricia

    2014-01-27

    Although membrane shape varies greatly throughout the cell, the contribution of membrane curvature to transmembrane protein targeting is unknown because of the numerous sorting mechanisms that take place concurrently in cells. To isolate the effect of membrane shape, we used cell-sized giant unilamellar vesicles (GUVs) containing either the potassium channel KvAP or the water channel AQP0 to form membrane nanotubes with controlled radii. Whereas the AQP0 concentrations in flat and curved membranes were indistinguishable, KvAP was enriched in the tubes, with greater enrichment in more highly curved membranes. Fluorescence recovery after photobleaching measurements showed that both proteins could freely diffuse through the neck between the tube and GUV, and the effect of each protein on membrane shape and stiffness was characterized using a thermodynamic sorting model. This study establishes the importance of membrane shape for targeting transmembrane proteins and provides a method for determining the effective shape and flexibility of membrane proteins. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Spatial distribution of cold antihydrogen formation

    International Nuclear Information System (INIS)

    Madsen, N.; Hangst, J.S.; Amoretti, M.; Carraro, C.; Macri, M.; Testera, G.; Variola, A.; Amsler, C.; Pruys, H.; Regenfus, C.; Bonomi, G.; Doser, M.; Kellerbauer, A.; Landua, R.; Bowe, P.D.; Charlton, M.; Joergensen, L.V.; Mitchard, D.; Werf, D.P. van der; Cesar, C.L.

    2005-01-01

    Antihydrogen is formed when antiprotons are mixed with cold positrons in a nested Penning trap. We present experimental evidence, obtained using our antihydrogen annihilation detector, that the spatial distribution of the emerging antihydrogen atoms is independent of the positron temperature and axially enhanced. This indicates that antihydrogen is formed before the antiprotons are in thermal equilibrium with the positron plasma. This result has important implications for the trapping and spectroscopy of antihydrogen

  13. Dynamic multiprotein assemblies shape the spatial structure of cell signaling.

    Science.gov (United States)

    Nussinov, Ruth; Jang, Hyunbum

    2014-01-01

    Cell signaling underlies critical cellular decisions. Coordination, efficiency as well as fail-safe mechanisms are key elements. How the cell ensures that these hallmarks are at play are important questions. Cell signaling is often viewed as taking place through discrete and cross-talking pathways; oftentimes these are modularized to emphasize distinct functions. While simple, convenient and clear, such models largely neglect the spatial structure of cell signaling; they also convey inter-modular (or inter-protein) spatial separation that may not exist. Here our thesis is that cell signaling is shaped by a network of multiprotein assemblies. While pre-organized, the assemblies and network are loose and dynamic. They contain transiently-associated multiprotein complexes which are often mediated by scaffolding proteins. They are also typically anchored in the membrane, and their continuum may span the cell. IQGAP1 scaffolding protein which binds proteins including Raf, calmodulin, Mek, Erk, actin, and tens more, with actin shaping B-cell (and likely other) membrane-anchored nanoclusters and allosterically polymerizing in dynamic cytoskeleton formation, and Raf anchoring in the membrane along with Ras, provides a striking example. The multivalent network of dynamic proteins and lipids, with specific interactions forming and breaking, can be viewed as endowing gel-like properties. Collectively, this reasons that efficient, productive and reliable cell signaling takes place primarily through transient, preorganized and cooperative protein-protein interactions spanning the cell rather than stochastic, diffusion-controlled processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. The shape of terrestrial abundance distributions

    Science.gov (United States)

    Alroy, John

    2015-01-01

    Ecologists widely accept that the distribution of abundances in most communities is fairly flat but heavily dominated by a few species. The reason for this is that species abundances are thought to follow certain theoretical distributions that predict such a pattern. However, previous studies have focused on either a few theoretical distributions or a few empirical distributions. I illustrate abundance patterns in 1055 samples of trees, bats, small terrestrial mammals, birds, lizards, frogs, ants, dung beetles, butterflies, and odonates. Five existing theoretical distributions make inaccurate predictions about the frequencies of the most common species and of the average species, and most of them fit the overall patterns poorly, according to the maximum likelihood–related Kullback-Leibler divergence statistic. Instead, the data support a low-dominance distribution here called the “double geometric.” Depending on the value of its two governing parameters, it may resemble either the geometric series distribution or the lognormal series distribution. However, unlike any other model, it assumes both that richness is finite and that species compete unequally for resources in a two-dimensional niche landscape, which implies that niche breadths are variable and that trait distributions are neither arrayed along a single dimension nor randomly associated. The hypothesis that niche space is multidimensional helps to explain how numerous species can coexist despite interacting strongly. PMID:26601249

  15. Spatial Distribution of Flower Color Induced by Interspecific Sexual Interaction.

    Directory of Open Access Journals (Sweden)

    Yuma Takahashi

    Full Text Available Understanding the mechanisms shaping the spatiotemporal distribution of species has long been a central concern of ecology and evolutionary biology. Contemporary patterns of plant assemblies suggest that sexual interactions among species, i.e., reproductive interference, lead to the exclusive distributions of closely related species that share pollinators. However, the fitness consequences and the initial ecological/evolutionary responses to reproductive interference remain unclear in nature, since reproductive isolation or allopatric distribution has already been achieved in the natural community. In Japan, three species of blue-eyed grasses (Sisyrinchium with incomplete reproductive isolation have recently colonized and occur sympatrically. Two of them are monomorphic with white flowers, whereas the other exhibits heritable color polymorphism (white and purple morphs. Here we investigated the effects of the presence of two monomorphic species on the distribution and reproductive success of color morphs. The frequency and reproductive success of white morphs decreased in area where monomorphic species were abundant, while those of purple morphs did not. The rate of hybridization between species was higher in white morphs than in the purple ones. Resource competition and habitat preference seemed not to contribute to the spatial distribution and reproductive success of two morphs. Our results supported that color-dependent reproductive interference determines the distribution of flower color polymorphism in a habitat, implying ecological sorting promoted by pollinator-mediated reproductive interference. Our study helps us to understand the evolution and spatial structure of flower color in a community.

  16. Spatial distribution of suicide in Queensland, Australia

    Directory of Open Access Journals (Sweden)

    Tong Shilu

    2010-12-01

    Full Text Available Abstract Background There has been a lack of investigation into the spatial distribution and clustering of suicide in Australia, where the population density is lower than many countries and varies dramatically among urban, rural and remote areas. This study aims to examine the spatial distribution of suicide at a Local Governmental Area (LGA level and identify the LGAs with a high relative risk of suicide in Queensland, Australia, using geographical information system (GIS techniques. Methods Data on suicide and demographic variables in each LGA between 1999 and 2003 were acquired from the Australian Bureau of Statistics. An age standardised mortality (ASM rate for suicide was calculated at the LGA level. GIS techniques were used to examine the geographical difference of suicide across different areas. Results Far north and north-eastern Queensland (i.e., Cook and Mornington Shires had the highest suicide incidence in both genders, while the south-western areas (i.e., Barcoo and Bauhinia Shires had the lowest incidence in both genders. In different age groups (≤24 years, 25 to 44 years, 45 to 64 years, and ≥65 years, ASM rates of suicide varied with gender at the LGA level. Mornington and six other LGAs with low socioeconomic status in the upper Southeast had significant spatial clusters of high suicide risk. Conclusions There was a notable difference in ASM rates of suicide at the LGA level in Queensland. Some LGAs had significant spatial clusters of high suicide risk. The determinants of the geographical difference of suicide should be addressed in future research.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Abyssal ocean overturning shaped by seafloor distribution

    Science.gov (United States)

    de Lavergne, C.; Madec, G.; Roquet, F.; Holmes, R. M.; McDougall, T. J.

    2017-11-01

    The abyssal ocean is broadly characterized by northward flow of the densest waters and southward flow of less-dense waters above them. Understanding what controls the strength and structure of these interhemispheric flows—referred to as the abyssal overturning circulation—is key to quantifying the ocean’s ability to store carbon and heat on timescales exceeding a century. Here we show that, north of 32° S, the depth distribution of the seafloor compels dense southern-origin waters to flow northward below a depth of about 4 kilometres and to return southward predominantly at depths greater than 2.5 kilometres. Unless ventilated from the north, the overlying mid-depths (1 to 2.5 kilometres deep) host comparatively weak mean meridional flow. Backed by analysis of historical radiocarbon measurements, the findings imply that the geometry of the Pacific, Indian and Atlantic basins places a major external constraint on the overturning structure.

  2. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mackey, H.E. [Westinghouse Savannah River Company, AIKEN, SC (United States); Ehler, G.B.; Cowen, D. [South Carolina Univ., Columbia, SC (United States)

    1996-05-31

    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

  4. 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

  5. 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.

  6. 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

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

    Science.gov (United States)

    Fowler, Mike S; Ruokolainen, Lasse

    2013-01-01

    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 must let

  8. 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...... for increasing the realism of 3D objects such as bump mapping. This extensible framework helps us identify challenges of the two techniques and benefits of their combination. We utilize our prototype shape-changing device enriched with spatial augmented reality through projection mapping to demonstrate...... the concept. We present a novel mechanical distance-fields algorithm for real-time fitting of mechanically constrained shape-changing devices to arbitrary 3D graphics. Furthermore, we present a technique for increasing effective screen real estate for spatial augmented reality through view-dependent shape...

  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

    2013-02-01

    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 km(2) 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. Spatial Distribution Analysis of Scrub Typhus in Korea

    OpenAIRE

    Jin, Hong Sung; Chu, Chaeshin; Han, Dong Yeob

    2013-01-01

    Objective: This study analyzes the spatial distribution of scrub typhus in Korea. Methods: A spatial distribution of Orientia tsutsugamushi occurrence using a geographic information system (GIS) is presented, and analyzed by means of spatial clustering and correlations. Results: The provinces of Gangwon-do and Gyeongsangbuk-do show a low incidence throughout the year. Some districts have almost identical environmental conditions of scrub typhus incidence. The land use change of districts does...

  11. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Wei Kang; Denton, Alan R., E-mail: alan.denton@ndsu.edu [Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 (United States)

    2014-09-21

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments.

  12. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    International Nuclear Information System (INIS)

    Lim, Wei Kang; Denton, Alan R.

    2014-01-01

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments

  13. 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

  14. 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.

  15. 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

    We present a new method for automatic classification of indirect immunoflourescence images of HEp-2 cells into different staining pattern classes. Our method is based on a new texture measure called shape index histograms that captures second-order image structure at multiple scales. Moreover, we...... datasets. Our results show that shape index histograms are superior to other popular texture descriptors for HEp-2 cell classification. Moreover, when comparing to other automated systems for HEp-2 cell classification we show that shape index histograms are very competitive; especially considering...

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Makhsiyan, Mathilde [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Bouchon, Patrick, E-mail: patrick.bouchon@onera.fr; Jaeck, Julien [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); Pelouard, Jean-Luc [MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Haïdar, Riad [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); École Polytechnique, Département de Physique, 91128 Palaiseau (France)

    2015-12-21

    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.

  18. 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...

  19. 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....

  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. Does Environmental Experience Shape Spatial Cognition? Frames of Reference among Ancash Quechua Speakers (Peru)

    Science.gov (United States)

    Shapero, Joshua A.

    2017-01-01

    Previous studies have shown that language contributes to humans' ability to orient using landmarks and shapes their use of frames of reference (FoRs) for memory. However, the role of environmental experience in shaping spatial cognition has not been investigated. This study addresses such a possibility by examining the use of FoRs in a nonverbal…

  2. 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.

  3. Spatial distribution and landuse planning of informal automobile ...

    African Journals Online (AJOL)

    Spatial distribution and landuse planning of informal automobile workshops in Osogbo, ... data pertaining to the activities and other related issues of their workshops. ... The study therefore, recommends the establishment of mechanic complex, ...

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

    African Journals Online (AJOL)

    The spatial distribution of aquatic macroinvertebrates in the Okavango River ... of taxa was recorded in marginal vegetation in the channels and lagoons, ... highlights the importance of maintaining a mosaic of aquatic habitats in the Delta.

  5. 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, ... seasonally-flooded pools and temporary rain-filled pools in MGR and CI. ... biodiversity of the Okavango Delta, thereby contributing to its conservation.

  6. 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)

  7. Coded aperture imaging of alpha source spatial distribution

    International Nuclear Information System (INIS)

    Talebitaher, Alireza; Shutler, Paul M.E.; Springham, Stuart V.; Rawat, Rajdeep S.; Lee, Paul

    2012-01-01

    The Coded Aperture Imaging (CAI) technique has been applied with CR-39 nuclear track detectors to image alpha particle source spatial distributions. The experimental setup comprised: a 226 Ra source of alpha particles, a laser-machined CAI mask, and CR-39 detectors, arranged inside a vacuum enclosure. Three different alpha particle source shapes were synthesized by using a linear translator to move the 226 Ra source within the vacuum enclosure. The coded mask pattern used is based on a Singer Cyclic Difference Set, with 400 pixels and 57 open square holes (representing ρ = 1/7 = 14.3% open fraction). After etching of the CR-39 detectors, the area, circularity, mean optical density and positions of all candidate tracks were measured by an automated scanning system. Appropriate criteria were used to select alpha particle tracks, and a decoding algorithm applied to the (x, y) data produced the de-coded image of the source. Signal to Noise Ratio (SNR) values obtained for alpha particle CAI images were found to be substantially better than those for corresponding pinhole images, although the CAI-SNR values were below the predictions of theoretical formulae. Monte Carlo simulations of CAI and pinhole imaging were performed in order to validate the theoretical SNR formulae and also our CAI decoding algorithm. There was found to be good agreement between the theoretical formulae and SNR values obtained from simulations. Possible reasons for the lower SNR obtained for the experimental CAI study are discussed.

  8. Perceived loudness of spatially distributed sound sources

    DEFF Research Database (Denmark)

    Song, Woo-keun; Ellermeier, Wolfgang; Minnaar, Pauli

    2005-01-01

    psychoacoustic attributes into account. Therefore, a method for deriving loudness maps was developed in an earlier study [Song, Internoise2004, paper 271]. The present experiment investigates to which extent perceived loudness depends on the distribution of individual sound sources. Three loudspeakers were...... positioned 1.5 m from the centre of the listener’s head, one straight ahead, and two 10 degrees to the right and left, respectively. Six participants matched the loudness of either one, or two simultaneous sounds (narrow-band noises with 1-kHz, and 3.15-kHz centre frequencies) to a 2-kHz, 60-dB SPL narrow......-band noise placed in the frontal loudspeaker. The two sounds were either originating from the central speaker, or from the two offset loudspeakers. It turned out that the subjects perceived the noises to be softer when they were distributed in space. In addition, loudness was calculated from the recordings...

  9. Spatial distribution of Dermacentor reticulatus in Romania.

    Science.gov (United States)

    Chitimia-Dobler, Lidia

    2015-11-30

    Dermacentor reticulatus (Fabricius, 1794), also known as the marsh tick or ornate dog tick is the second most significant vector (next to Ixodes ricinus) of protozoan, rickettsial and viral pathogens in Europe. Until now, only limited information on the distribution of D. reticulatus in Romania is available. A study was conducted on the distribution of D. reticulatus in Romania during 2012-2014. In this study, D. reticulatus was detected in 17 counties, in 14 of which the species was recorded for the first time. Tick activity was evident throughout the year, except during July and August. Additionally, D. reticulatus was recorded for the first time in Romania from wild boar, foxes and humans. These data suggest that this tick species has a broader geographic range and may have more veterinary and medical importance than previously known. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. 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.

  11. Local topography shapes fine-scale spatial genetic structure in the Arkansas Valley evening primrose, Oenothera harringtonii (Onagraceae).

    Science.gov (United States)

    Rhodes, Matthew K; Fant, Jeremie B; Skogen, Krissa A

    2014-01-01

    Identifying factors that shape the spatial distribution of genetic variation is crucial to understanding many population- and landscape-level processes. In this study, we explore fine-scale spatial genetic structure in Oenothera harringtonii (Onagraceae), an insect-pollinated, gravity-dispersed herb endemic to the grasslands of south-central and southeastern Colorado, USA. We genotyped 315 individuals with 11 microsatellite markers and utilized a combination of spatial autocorrelation analyses and landscape genetic models to relate life history traits and landscape features to dispersal processes. Spatial genetic structure was consistent with theoretical expectations of isolation by distance, but this pattern was weak (Sp = 0.00374). Anisotropic analyses indicated that spatial genetic structure was markedly directional, in this case consistent with increased dispersal along prominent slopes. Landscape genetic models subsequently confirmed that spatial genetic variation was significantly influenced by local topographic heterogeneity, specifically that geographic distance, elevation and aspect were important predictors of spatial genetic structure. Among these variables, geographic distance was ~68% more important than elevation in describing spatial genetic variation, and elevation was ~42% more important than aspect after removing the effect of geographic distance. From these results, we infer a mechanism of hydrochorous seed dispersal along major drainages aided by seasonal monsoon rains. Our findings suggest that landscape features may shape microevolutionary processes at much finer spatial scales than typically considered, and stress the importance of considering how particular dispersal vectors are influenced by their environmental context. © The American Genetic Association 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Spatially distributed multipartite entanglement enables EPR steering of atomic clouds

    Science.gov (United States)

    Kunkel, Philipp; Prüfer, Maximilian; Strobel, Helmut; Linnemann, Daniel; Frölian, Anika; Gasenzer, Thomas; Gärttner, Martin; Oberthaler, Markus K.

    2018-04-01

    A key resource for distributed quantum-enhanced protocols is entanglement between spatially separated modes. However, the robust generation and detection of entanglement between spatially separated regions of an ultracold atomic system remain a challenge. We used spin mixing in a tightly confined Bose-Einstein condensate to generate an entangled state of indistinguishable particles in a single spatial mode. We show experimentally that this entanglement can be spatially distributed by self-similar expansion of the atomic cloud. We used spatially resolved spin read-out to reveal a particularly strong form of quantum correlations known as Einstein-Podolsky-Rosen (EPR) steering between distinct parts of the expanded cloud. Based on the strength of EPR steering, we constructed a witness, which confirmed genuine 5-partite entanglement.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dufour, G.; Lambrecht, A.; Reynaud, S. [CNRS, ENS, UPMC, Laboratoire Kastler-Brossel, Paris (France); Debu, P. [CEA-Saclay, Institut de Recherche sur les lois Fondamentales de l' Univers, Gif-sur-Yvette (France); Nesvizhevsky, V.V. [Institut Max von Laue-Paul Langevin, Grenoble (France); Voronin, A.Yu. [P.N. Lebedev Physical Institute, Moscow (Russian Federation)

    2014-01-15

    GBAR is a project aiming at measuring the freefall acceleration of gravity for antimatter, namely antihydrogen atoms (H). The 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 the vertical velocities of H, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing 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 we show that the accuracy for measuring the free fall acceleration g of H could be pushed below 10{sup -3} under realistic experimental conditions. (orig.)

  14. 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.

  15. Ionizing nightglow: sources, intensity, and spatial distribution

    International Nuclear Information System (INIS)

    Young, J.M.; Troy, B.E. Jr.; Johnson, C.Y.; Holmes, J.C.

    1975-01-01

    Photometers carried aboard an Aerobee rocket mapped the ultraviolet night sky at White Sands, New Mexico. Maps for five 300 A passbands in the wavelength range 170 to 1400 A reveal spatial radiation patterns unique to each spectral subregion. The major ultraviolet features seen in these maps are ascribed to a variety of sources: 1) solar Lyman α (1216 A) and Lyman β (1026 A), resonantly scattered by geocoronal hydrogen; 2) solar HeII (304 A) resonantly scattered by ionized helium in the Earth's plasmasphere; 3) solar HeI (584 A) resonantly scattered by neutral helium in the interstellar wind and Doppler shifted so that it penetrates the Earth's helium blanket; and 4) starlight in the 912 to 1400 A band, primarily from early-type stars in the Orion region. Not explained are the presence of small, but measurable, albedo signals observed near the peak of flight. Intensities vary from several kilorayleighs for Lyman α to a few rayleighs for HeII. (auth)

  16. 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

  17. Quantification of the spatial strain distribution of scoliosis using a thin-plate spline method.

    Science.gov (United States)

    Kiriyama, Yoshimori; Watanabe, Kota; Matsumoto, Morio; Toyama, Yoshiaki; Nagura, Takeo

    2014-01-03

    The objective of this study was to quantify the three-dimensional spatial strain distribution of a scoliotic spine by nonhomogeneous transformation without using a statistically averaged reference spine. The shape of the scoliotic spine was determined from computed tomography images from a female patient with adolescent idiopathic scoliosis. The shape of the scoliotic spine was enclosed in a rectangular grid, and symmetrized using a thin-plate spline method according to the node positions of the grid. The node positions of the grid were determined by numerical optimization to satisfy symmetry. The obtained symmetric spinal shape was enclosed within a new rectangular grid and distorted back to the original scoliotic shape using a thin-plate spline method. The distorted grid was compared to the rectangular grid that surrounded the symmetrical spine. Cobb's angle was reduced from 35° in the scoliotic spine to 7° in the symmetrized spine, and the scoliotic shape was almost fully symmetrized. The scoliotic spine showed a complex Green-Lagrange strain distribution in three dimensions. The vertical and transverse compressive/tensile strains in the frontal plane were consistent with the major scoliotic deformation. The compressive, tensile and shear strains on the convex side of the apical vertebra were opposite to those on the concave side. These results indicate that the proposed method can be used to quantify the three-dimensional spatial strain distribution of a scoliotic spine, and may be useful in quantifying the deformity of scoliosis. © 2013 Elsevier Ltd. All rights reserved.

  18. 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.

  19. 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, ...

  20. Spatial distribution of soluble insulin in pig subcutaneous tissue

    DEFF Research Database (Denmark)

    Thomsen, Maria; Rasmussen, Christian Hove; Refsgaard, Hanne H F

    2015-01-01

    in the tomographic reconstructions and the amount of drug in each tissue class was quantified. With a scan time of about 45min per sample, and a robust segmentation it was possible to analyze differences in the spatial drug distribution between several similar injections. It was studied how the drug distribution...

  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. 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.

  3. Spatial distribution maps for benthic communities

    DEFF Research Database (Denmark)

    Sørensen, Per S.

    1999-01-01

    ecosystems, were selected. These species are supposed to be good indicators of marine ecosystem health. The hydroacoustic measurements comprise preprocessed echo sounder recordings and side-scan sonar data forming a large and unique collection of datasets based on 4 field campaigns in Øresund...... of the distribution maps and to be combined with biogeochemical models describing spatiotemporal population dynamics. Finally, the use of side-scan sonar data is illustrated in a data fusion exercise combining side-scan sonar data with the results based on echo sounder measurements. The feasible use of side......-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...

  4. 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.

  5. 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.

  6. 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

  7. A digital elevation analysis: Spatially distributed flow apportioning algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang-Hyun; Kim, Kyung-Hyun [Pusan National University, Pusan(Korea); Jung, Sun-Hee [Korea Environment Institute, (Korea)

    2001-06-30

    A flow determination algorithm is proposed for the distributed hydrologic model. The advantages of a single flow direction scheme and multiple flow direction schemes are selectively considered to address the drawbacks of existing algorithms. A spatially varied flow apportioning factor is introduced in order to accommodate the accumulated area from upslope cells. The channel initiation threshold area(CIT) concept is expanded and integrated into the spatially distributed flow apportioning algorithm in order to delineate a realistic channel network. An application of a field example suggests that the linearly distributed flow apportioning scheme provides some advantages over existing approaches, such as the relaxation of over-dissipation problems near channel cells, the connectivity feature of river cells, the continuity of saturated areas and the negligence of the optimization of few parameters in existing algorithms. The effects of grid sizes are explored spatially as well as statistically. (author). 28 refs., 7 figs.

  8. 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

  9. 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

  10. 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

  11. 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 on the pixels between zero and two pi for a specific wavelength. It is therefore unavoidable when using the same SLM, to do beam shaping of a source which emits multiple wavelengths or a wide bandwidth, that the device will not modulate all wavelengths between...

  12. Experimental study of spatial distribution of Ar glow discharge plasma

    International Nuclear Information System (INIS)

    Guo, X.M.; Zhou, T.D.; Pai, S.T.

    1996-01-01

    The characteristics of the spatial distribution of Ar glow discharge plasma were experimentally investigated. By means of direct comparisons between theory and experiment, the effects of the variation of gap separation, gas pressure, and electrode radius on the spatial distributions of electron density and electric field were studied. Results indicate that the maximum electron density moves toward the cathode as the gap separation or gas pressure increases while variation of electrode radius produces little effect. Predictions from a theoretical model have been experimentally verified. General agreements between theory and experiment were found to be reasonably good except in the cathode region, where discrepancy exists. copyright 1996 American Institute of Physics

  13. 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

    -pattern by Acinetobacter sp. C6. Ecological spatial pattern analyses revealed that the microcolonies were not entirely randomly distributed, and instead arranged in a uniform pattern. Detailed time-lapse confocal microscopy at the single cell level demonstrated that the spatial pattern was the result of an intriguing self......-organization: Small multicellular clusters moved along the surface to fuse with one another to form microcolonies. This active distribution capability was dependent on environmental factors (carbon source, oxygen) and historical contingency (formation of phenotypic variants). The findings of this study are discussed...

  14. Non-homogeneous Behaviour of the Spatial Distribution of Macrospicules

    Science.gov (United States)

    Gyenge, N.; Bennett, S.; Erdélyi, R.

    2015-03-01

    In this paper the longitudinal and latitudinal spatial distribution of macrospicules is examined. We found a statistical relationship between the active longitude (determined by sunspot groups) and the longitudinal distribution of macrospicules. This distribution of macrospicules shows an inhomogeneity and non-axisymmetrical behaviour in the time interval between June 2010 and December 2012, covered by observations of the Solar Dynamic Observatory (SDO) satellite. The enhanced 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.

  15. Unleashing spatially distributed ecohydrology modeling using Big Data tools

    Science.gov (United States)

    Miles, B.; Idaszak, R.

    2015-12-01

    Physically based spatially distributed ecohydrology models are useful for answering science and management questions related to the hydrology and biogeochemistry of prairie, savanna, forested, as well as urbanized ecosystems. However, these models can produce hundreds of gigabytes of spatial output for a single model run over decadal time scales when run at regional spatial scales and moderate spatial resolutions (~100-km2+ at 30-m spatial resolution) or when run for small watersheds at high spatial resolutions (~1-km2 at 3-m spatial resolution). Numerical data formats such as HDF5 can store arbitrarily large datasets. However even in HPC environments, there are practical limits on the size of single files that can be stored and reliably backed up. Even when such large datasets can be stored, querying and analyzing these data can suffer from poor performance due to memory limitations and I/O bottlenecks, for example on single workstations where memory and bandwidth are limited, or in HPC environments where data are stored separately from computational nodes. The difficulty of storing and analyzing spatial data from ecohydrology models limits our ability to harness these powerful tools. Big Data tools such as distributed databases have the potential to surmount the data storage and analysis challenges inherent to large spatial datasets. Distributed databases solve these problems by storing data close to computational nodes while enabling horizontal scalability and fault tolerance. Here we present the architecture of and preliminary results from PatchDB, a distributed datastore for managing spatial output from the Regional Hydro-Ecological Simulation System (RHESSys). The initial version of PatchDB uses message queueing to asynchronously write RHESSys model output to an Apache Cassandra cluster. Once stored in the cluster, these data can be efficiently queried to quickly produce both spatial visualizations for a particular variable (e.g. maps and animations), as well

  16. 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...

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

    KAUST Repository

    Balzer, Jonathan

    2011-01-01

    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

  18. 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)

  19. Unbiased estimators for spatial distribution functions of classical fluids

    Science.gov (United States)

    Adib, Artur B.; Jarzynski, Christopher

    2005-01-01

    We use a statistical-mechanical identity closely related to the familiar virial theorem, to derive unbiased estimators for spatial distribution functions of classical fluids. In particular, we obtain estimators for both the fluid density ρ(r) in the vicinity of a fixed solute and the pair correlation g(r) of a homogeneous classical fluid. We illustrate the utility of our estimators with numerical examples, which reveal advantages over traditional histogram-based methods of computing such distributions.

  20. 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)

  1. Using a Neural Network Approach to Find Unusual Butterfly Pitch Angle Distribution Shapes

    Science.gov (United States)

    Medeiros, C.; Sibeck, D. G.; Souza, V. M. C. E. S.; Vieira, L.; Alves, L. R.; Da Silva, L. A.; Kanekal, S. G.; Baker, D. N.

    2017-12-01

    A special kind of neural network referred to as a Self-Organizing Map (SOM) was previously adopted to identify, in pitch angle-resolved relativistic electron flux data provided by the REPT instrument onboard the Van Allen Probes, three major types of electron pitch angle distributions (PADs), namely 90o-peaked, butterfly and flattop (Souza et al., 2016), following the classification scheme employed by Gannon et al. (2007). Previous studies show that butterfly distribution can be found in more than one shape. They usually exhibit an intense decrease near 90° pitch angles compared to the peaks usually around 30° and 150°. Sometimes unusual butterfly PAD shapes with peaks near 45° and 135° pitch angles can be observed. These could be correlated with different physical processes that govern the production and loss of energetic particles in the Van Allen radiation belt. A neural network approach allows the distinction of different kinds of butterfly PADs which were not analyzed in detail by Souza et al. (2016). This study uses SOM methodology to find these unusual butterfly PAD shape during the interval between January 1, 2014 and October 1, 2015, during which Van Allen Probes orbit covered all MLT. The spatial and temporal occurrence of these events were investigated as well as their solar wind and magnetospheric drivers.

  2. 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.

  3. 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…

  4. 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, ...

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

    African Journals Online (AJOL)

    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 of ...

  6. 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.

  7. 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 ...

  8. 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 ...

  9. Analysis of thrips distribution: application of spatial statistics and Kriging

    Science.gov (United States)

    John Aleong; Bruce L. Parker; Margaret Skinner; Diantha Howard

    1991-01-01

    Kriging is a statistical technique that provides predictions for spatially and temporally correlated data. Observations of thrips distribution and density in Vermont soils are made in both space and time. Traditional statistical analysis of such data assumes that the counts taken over space and time are independent, which is not necessarily true. Therefore, to analyze...

  10. 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 ...

  11. 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.

  12. 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

  13. 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...

  14. 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.

  15. 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.

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

    KAUST Repository

    Cannicci, Stefano; Fusi, Marco; Cimó , Filippo; Dahdouh-Guebas, Farid; Fratini, Sara

    2018-01-01

    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.

  17. 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.

  18. 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

  19. 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...

  20. 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

  1. Stellar bars and the spatial distribution of infrared luminosity

    International Nuclear Information System (INIS)

    Devereux, N.

    1987-01-01

    Ground-based 10 micron observations of the central region of over 100 infrared luminous galaxies are presented. A first order estimate of the spatial distribution of infrared emission in galaxies is obtained through a combination of ground-based and Infrared Astronomy Satellite (IRAS) data. The galaxies are nearby and primarily noninteracting, permitting an unbiased investigation of correlations with Hubble type. Approximately 40% of the early-type barred galaxies in this sample are associated with enhanced luminosity in the central (approximately 1 kpc diameter) region. The underlying luminosity source is attributed to both Seyfert and star formation activity. Late-type spirals are different in that the spatial distribution of infrared emission and the infrared luminoisty are not strongly dependent on barred morphology

  2. 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.

  3. 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.

  4. Investigation of an He-Ne laser generating a beam with a ring-shaped intensity distribution

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, I I; Troitskii, IU V; Iakushkin, S V

    1987-02-01

    The paper examines an He-Ne laser regime with the simultaneous generation of TEM(01) and TEM(10) modes, forming a beam with a ring-shaped intensity distribution with total suppression of the TEM(00) mode. The ratio of the intensity at the ring crest to the intensity at the axis reached a value of 200 and was limited by scattering in the optical components of the resonator. A regime of mutual frequency locking of the TEM(01) and TEM(10) modes was achieved with total spatial coherence of the ring-shaped beam. 14 references.

  5. 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)

  6. 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.

  7. 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).

  8. Variability of the raindrop size distribution at small spatial scales

    Science.gov (United States)

    Berne, A.; Jaffrain, J.

    2010-12-01

    Because of the interactions between atmospheric turbulence and cloud microphysics, the raindrop size distribution (DSD) is strongly variable in space and time. The spatial variability of the DSD at small spatial scales (below a few km) is not well documented and not well understood, mainly because of a lack of adequate measurements at the appropriate resolutions. A network of 16 disdrometers (Parsivels) has been designed and set up over EPFL campus in Lausanne, Switzerland. This network covers a typical operational weather radar pixel of 1x1 km2. The question of the significance of the variability of the DSD at such small scales is relevant for radar remote sensing of rainfall because the DSD is often assumed to be uniform within a radar sample volume and because the Z-R relationships used to convert the measured radar reflectivity Z into rain rate R are usually derived from point measurements. Thanks to the number of disdrometers, it was possible to quantify the spatial variability of the DSD at the radar pixel scale and to show that it can be significant. In this contribution, we show that the variability of the total drop concentration, of the median volume diameter and of the rain rate are significant, taking into account the sampling uncertainty associated with disdrometer measurements. The influence of this variability on the Z-R relationship can be non-negligible. Finally, the spatial structure of the DSD is quantified using a geostatistical tool, the variogram, and indicates high spatial correlation within a radar pixel.

  9. Spatial distribution of spin polarization in a channel on the surface of a topological insulator

    International Nuclear Information System (INIS)

    Zhou Xiaoying; Shao Huaihua; Liu Yiman; Tang Dongsheng; Zhou Guanghui

    2012-01-01

    We study the spatial distribution of electron spin polarization for a gate-controlled T-shaped channel on the surface of a three-dimensional topological insulator (3D TI). We demonstrate that an energy gap depending on channel geometry parameters is definitely opened due to the spatial confinement. Spin surface locking in momentum space for a uniform wide channel with Hamiltonian linearity in the wavevector is still kept, but it is broken with Hamiltonian nonlinearity in the wavevector, like that for two-dimensional surface states widely studied in the literature. However, the spin surface locking for a T-shaped channel is broken even with Hamiltonian linearity in the wavevector. Interestingly, the magnitude and direction of the in-plane spin polarization are spatially dependent in all regions due to the breaking of translational symmetry of the T-shaped channel system. These interesting findings for an electrically controlled nanostructure based on the 3D TI surface may be testable with the present experimental technique, and may provide further understanding the nature of 3D TI surface states. (paper)

  10. Cell shape can mediate the spatial organization of the bacterial cytoskeleton

    Science.gov (United States)

    Wang, Siyuan; Wingreen, Ned

    2013-03-01

    The bacterial cytoskeleton guides the synthesis of cell wall and thus regulates cell shape. Since spatial patterning of the bacterial cytoskeleton is critical to the proper control of cell shape, it is important to ask how the cytoskeleton spatially self-organizes in the first place. In this work, we develop a quantitative model to account for the various spatial patterns adopted by bacterial cytoskeletal proteins, especially the orientation and length of cytoskeletal filaments such as FtsZ and MreB in rod-shaped cells. We show that the combined mechanical energy of membrane bending, membrane pinning, and filament bending of a membrane-attached cytoskeletal filament can be sufficient to prescribe orientation, e.g. circumferential for FtsZ or helical for MreB, with the accuracy of orientation increasing with the length of the cytoskeletal filament. Moreover, the mechanical energy can compete with the chemical energy of cytoskeletal polymerization to regulate filament length. Notably, we predict a conformational transition with increasing polymer length from smoothly curved to end-bent polymers. Finally, the mechanical energy also results in a mutual attraction among polymers on the same membrane, which could facilitate tight polymer spacing or bundling. The predictions of the model can be verified through genetic, microscopic, and microfluidic approaches.

  11. Fast automated segmentation of multiple objects via spatially weighted shape learning

    Science.gov (United States)

    Chandra, Shekhar S.; Dowling, Jason A.; Greer, Peter B.; Martin, Jarad; Wratten, Chris; Pichler, Peter; Fripp, Jurgen; Crozier, Stuart

    2016-11-01

    Active shape models (ASMs) have proved successful in automatic segmentation by using shape and appearance priors in a number of areas such as prostate segmentation, where accurate contouring is important in treatment planning for prostate cancer. The ASM approach however, is heavily reliant on a good initialisation for achieving high segmentation quality. This initialisation often requires algorithms with high computational complexity, such as three dimensional (3D) image registration. In this work, we present a fast, self-initialised ASM approach that simultaneously fits multiple objects hierarchically controlled by spatially weighted shape learning. Prominent objects are targeted initially and spatial weights are progressively adjusted so that the next (more difficult, less visible) object is simultaneously initialised using a series of weighted shape models. The scheme was validated and compared to a multi-atlas approach on 3D magnetic resonance (MR) images of 38 cancer patients and had the same (mean, median, inter-rater) Dice’s similarity coefficients of (0.79, 0.81, 0.85), while having no registration error and a computational time of 12-15 min, nearly an order of magnitude faster than the multi-atlas approach.

  12. 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.

  13. Spatial distribution of limited resources and local density regulation in juvenile Atlantic salmon.

    Science.gov (United States)

    Finstad, Anders G; Einum, Sigurd; Ugedal, Ola; Forseth, Torbjørn

    2009-01-01

    1. Spatial heterogeneity of resources may influence competition among individuals and thus have a fundamental role in shaping population dynamics and carrying capacity. In the present study, we identify shelter opportunities as a limiting resource for juvenile Atlantic salmon (Salmo salar L.). Experimental and field studies are combined in order to demonstrate how the spatial distribution of shelters may influence population dynamics on both within and among population scales. 2. In closed experimental streams, fish performance scaled negatively with decreasing shelter availability and increasing densities. In contrast, the fish in open stream channels dispersed according to shelter availability and performance of fish remaining in the streams did not depend on initial density or shelters. 3. The field study confirmed that spatial variation in densities of 1-year-old juveniles was governed both by initial recruit density and shelter availability. Strength of density-dependent population regulation, measured as carrying capacity, increased with decreasing number of shelters. 4. Nine rivers were surveyed for spatial variation in shelter availability and increased shelter heterogeneity tended to decrease maximum observed population size (measured using catch statistics of adult salmon as a proxy). 5. Our studies highlight the importance of small-scale within-population spatial structure in population dynamics and demonstrate that not only the absolute amount of limiting resources but also their spatial arrangement can be an important factor influencing population carrying capacity.

  14. 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

  15. 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.

  16. Graphic display of spatially distributed binary-state experimental data

    International Nuclear Information System (INIS)

    Watson, B.L.

    1981-01-01

    Experimental data collected from a large number of transducers spatially distributed throughout a three-dimensional volume has typically posed a difficult interpretation task for the analyst. This paper describes one approach to alleviating this problem by presenting color graphic displays of experimental data; specifically, data representing the dynamic three-dimensional distribution of cooling fluid collected during the reflood and refill of simulated nuclear reactor vessels. Color-coded binary data (wet/dry) are integrated with a graphic representation of the reactor vessel and displayed on a high-resolution color CRT. The display is updated with successive data sets and made into 16-mm movies for distribution and analysis. Specific display formats are presented and extension to other applications discussed

  17. Improving the accuracy of livestock distribution estimates through spatial interpolation.

    Science.gov (United States)

    Bryssinckx, Ward; Ducheyne, Els; Muhwezi, Bernard; Godfrey, Sunday; Mintiens, Koen; Leirs, Herwig; Hendrickx, Guy

    2012-11-01

    Animal distribution maps serve many purposes such as estimating transmission risk of zoonotic pathogens to both animals and humans. The reliability and usability of such maps is highly dependent on the quality of the input data. However, decisions on how to perform livestock surveys are often based on previous work without considering possible consequences. A better understanding of the impact of using different sample designs and processing steps on the accuracy of livestock distribution estimates was acquired through iterative experiments using detailed survey. The importance of sample size, sample design and aggregation is demonstrated and spatial interpolation is presented as a potential way to improve cattle number estimates. As expected, results show that an increasing sample size increased the precision of cattle number estimates but these improvements were mainly seen when the initial sample size was relatively low (e.g. a median relative error decrease of 0.04% per sampled parish for sample sizes below 500 parishes). For higher sample sizes, the added value of further increasing the number of samples declined rapidly (e.g. a median relative error decrease of 0.01% per sampled parish for sample sizes above 500 parishes. When a two-stage stratified sample design was applied to yield more evenly distributed samples, accuracy levels were higher for low sample densities and stabilised at lower sample sizes compared to one-stage stratified sampling. Aggregating the resulting cattle number estimates yielded significantly more accurate results because of averaging under- and over-estimates (e.g. when aggregating cattle number estimates from subcounty to district level, P interpolation to fill in missing values in non-sampled areas, accuracy is improved remarkably. This counts especially for low sample sizes and spatially even distributed samples (e.g. P <0.001 for a sample of 170 parishes using one-stage stratified sampling and aggregation on district level

  18. Behavioral correlates of the distributed coding of spatial context.

    Science.gov (United States)

    Anderson, Michael I; Killing, Sarah; Morris, Caitlin; O'Donoghue, Alan; Onyiagha, Dikennam; Stevenson, Rosemary; Verriotis, Madeleine; Jeffery, Kathryn J

    2006-01-01

    Hippocampal place cells respond heterogeneously to elemental changes of a compound spatial context, suggesting that they form a distributed code of context, whereby context information is shared across a population of neurons. The question arises as to what this distributed code might be useful for. The present study explored two possibilities: one, that it allows contexts with common elements to be disambiguated, and the other, that it allows a given context to be associated with more than one outcome. We used two naturalistic measures of context processing in rats, rearing and thigmotaxis (boundary-hugging), to explore how rats responded to contextual novelty and to relate this to the behavior of place cells. In experiment 1, rats showed dishabituation of rearing to a novel reconfiguration of familiar context elements, suggesting that they perceived the reconfiguration as novel, a behavior that parallels that of place cells in a similar situation. In experiment 2, rats were trained in a place preference task on an open-field arena. A change in the arena context triggered renewed thigmotaxis, and yet navigation continued unimpaired, indicating simultaneous representation of both the altered contextual and constant spatial cues. Place cells similarly exhibited a dual population of responses, consistent with the hypothesis that their activity underlies spatial behavior. Together, these experiments suggest that heterogeneous context encoding (or "partial remapping") by place cells may function to allow the flexible assignment of associations to contexts, a faculty that could be useful in episodic memory encoding. Copyright (c) 2006 Wiley-Liss, Inc.

  19. 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

  20. 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.

  1. Precise Mapping Of A Spatially Distributed Radioactive Source

    International Nuclear Information System (INIS)

    Beck, A.; Caras, I.; Piestum, S.; Sheli, E.; Melamud, Y.; Berant, S.; Kadmon, Y.; Tirosh, D.

    1999-01-01

    Spatial distribution measurement of radioactive sources is a routine task in the nuclear industry. The precision of each measurement depends upon the specific application. However, the technological edge of this precision is motivated by the production of standards for calibration. Within this definition, the most demanding field is the calibration of standards for medical equipment. In this paper, a semi-empirical method for controlling the measurement precision is demonstrated, using a relatively simple laboratory apparatus. The spatial distribution of the source radioactivity is measured as part of the quality assurance tests, during the production of flood sources. These sources are further used in calibration of medical gamma cameras. A typical flood source is a 40 x 60 cm 2 plate with an activity of 10 mCi (or more) of 57 Co isotope. The measurement set-up is based on a single NaI(Tl) scintillator with a photomultiplier tube, moving on an X Y table which scans the flood source. In this application the source is required to have a uniform activity distribution over its surface

  2. 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

  3. 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

  4. 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.

  5. The seven sisters DANCe. III. Projected spatial distribution

    Science.gov (United States)

    Olivares, J.; Moraux, E.; Sarro, L. M.; Bouy, H.; Berihuete, A.; Barrado, D.; Huelamo, N.; Bertin, E.; Bouvier, J.

    2018-04-01

    Context. Membership analyses of the DANCe and Tycho + DANCe data sets provide the largest and least contaminated sample of Pleiades candidate members to date. Aims: We aim at reassessing the different proposals for the number surface density of the Pleiades in the light of the new and most complete list of candidate members, and inferring the parameters of the most adequate model. Methods: We compute the Bayesian evidence and Bayes Factors for variations of the classical radial models. These include elliptical symmetry, and luminosity segregation. As a by-product of the model comparison, we obtain posterior distributions for each set of model parameters. Results: We find that the model comparison results depend on the spatial extent of the region used for the analysis. For a circle of 11.5 parsecs around the cluster centre (the most homogeneous and complete region), we find no compelling reason to abandon King's model, although the Generalised King model introduced here has slightly better fitting properties. Furthermore, we find strong evidence against radially symmetric models when compared to the elliptic extensions. Finally, we find that including mass segregation in the form of luminosity segregation in the J band is strongly supported in all our models. Conclusions: We have put the question of the projected spatial distribution of the Pleiades cluster on a solid probabilistic framework, and inferred its properties using the most exhaustive and least contaminated list of Pleiades candidate members available to date. Our results suggest however that this sample may still lack about 20% of the expected number of cluster members. Therefore, this study should be revised when the completeness and homogeneity of the data can be extended beyond the 11.5 parsecs limit. Such a study will allow for more precise determination of the Pleiades spatial distribution, its tidal radius, ellipticity, number of objects and total mass.

  6. 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.

  7. 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.

  8. 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.

  9. Spatial and temporal distribution of tropical biomass burning

    Science.gov (United States)

    Hao, Wei Min; Liu, Mei-Huey

    1994-12-01

    A database for the spatial and temporal distribution of the amount of biomass burned in tropical America, Africa, and Asia during the late 1970s is presented with a resolution of 5° latitude × 5° longitude. The sources of burning in each grid cell have been quantified. Savanna fires, shifting cultivation, deforestation, fuel wood use, and burning of agricultural residues contribute about 50, 24, 10, 11, and 5%, respectively, of total biomass burned in the tropics. Savanna fires dominate in tropical Africa, and forest fires dominate in tropical Asia. A similar amount of biomass is burned from forest and savanna fires in tropical America. The distribution of biomass burned monthly during the dry season has been derived for each grid cell using the seasonal cycles of surface ozone concentrations. Land use changes during the last decade could have a profound impact on the amount of biomass burned and the amount of trace gases and aerosol particles emitted.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. The Spatial Variability of Beryllium-7 Depth Distribution Study

    International Nuclear Information System (INIS)

    Jalal Sharib; Zainudin Othman; Dainee Nor Fardzila Ahmad Tugi; Noor Fadzilah Yusof; Mohd Tarmizi Ishak

    2015-01-01

    The objective of this paper is to study the spatial variability of 7 Be depth evolution in soil profile at two different sampling sites. The soil samples have been collected by using metal core in bare area in Bangi, Selangor and Timah Tasoh, Perlis , Malaysia. Two composite core samples for each sampling sites has been sectioned into 2 mm increments to a depth of 4 cm and oven dried at 45- 60 degree Celsius and gently desegregated. These two composite spatial samples are passed through a < 2 mm sieve and packed into proper geometry plastic container for 7 Be analysis by using gamma spectrometry with a 24-hour count time. From the findings, the 7 Be content in the soil samples from Bangi, Selangor study area is distributed lower depth penetration into the soil profile than Timah Tasoh, Perlis catchment due to many factors such as precipitation (fallout) and others. However, the spatial variability from both samples study area is also decreases exponentially with depth and is confined within the top few centimeters and similar with other works been reported (Blake et al., (2000) and Walling et al.,(2008). Furthermore, a detailed discussion from this study findings will be in full papers. (author)

  15. Temperature distributions in cladded configurations of complicated boundary shape

    International Nuclear Information System (INIS)

    Laura, P.A.A.; Gutierrez, R.H.; Sarmiento, G.S.

    1981-01-01

    This pape deals with an approximate analytical solution of certain cladded shapes of basic interest in nuclear engineering technology. In one case a solution of Laplace's equation is obtained. In the other, a solution to a system of partial differential equations (Poisson's and Laplace's) is attained. A approximate conformal mapping approach is also used in both situation, and it is shown that the analytical predictions are in good agreement with the values obtained by means of a finite element code. (orig.)

  16. 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.

  17. Research on spatial distribution of photosynthetic characteristics of Winter Wheat

    Science.gov (United States)

    Yan, Q. Q.; Zhou, Q. Y.; Zhang, B. Z.; Han, X.; Han, N. N.; Li, S. M.

    2018-03-01

    In order to explore the spatial distribution of photosynthetic characteristics of winter wheat leaf, the photosynthetic rate on different parts of leaf (leaf base-leaf middle-leaf apex) and that on each canopy (top layer-middle layer-bottom layer) leaf during the whole growth period of winter wheat were measured. The variation of photosynthetic rate with PAR and the spatial distribution of winter wheat leaf during the whole growth periods were analysed. The results showed that the photosynthetic rate of different parts of winter wheat increased with the increase of PAR, which was showed as leaf base>leaf middle>leaf apex. In the same growth period, photosynthetic rate in different parts of the tablet was showed as leaf middle>leaf base>leaf apex. For the different canopy layer of winter wheat, the photosynthetic rate of the top layer leaf was significantly greater than that of the middle layer and lower layer leaf. The photosynthetic rate of the top layer leaf was the largest in the leaf base position. The photosynthetic rate of leaf of the same canopy layer at different growth stages were showed as tasseling stage >grain filling stage > maturation stage.

  18. The spatial distribution of infrared radiation from visible reflection nebulae

    Science.gov (United States)

    Luan, Ling; Werner, Michael W.; Dwek, Eli; Sellgren, Kris

    1989-01-01

    The emission at IRAS 12 and 25 micron bands of reflection nebulae is far in excess of that expected from the longer wavelength equilibrium thermal emission. The excess emission in the IRAS 12 micron band is a general phenomenon, seen in various components of interstellar medium such as IR cirrus clouds, H II regions, atomic and molecular clouds, and also normal spiral galaxies. This excess emission has been attributed to UV excited fluorescence in polycyclic aromatic hydrocarbon (PAH) molecules or to the effect of temperature fluctuations in very small grains. Results are presented of studies of IRAS data on reflection nebulae selected from the van den Bergh reflection nebulae sample. Detailed scans of flux ratio and color temperature across the nebulae were obtained in order to study the spatial distribution of IR emission. A model was used to predict the spatial distribution of IR emission from dust grains illuminated by a B type star. The model was also used to explore the excitation of the IRAS 12 micron band emission as a function of stellar temperature. The model predictions are in good agreement with the analysis of reflection nebulae, illuminated by stars with stellar temperature ranging from 21,000 down to 3,000 K.

  19. 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.

  20. The role of spatial boundaries in shaping long-term event representations.

    Science.gov (United States)

    Horner, Aidan J; Bisby, James A; Wang, Aijing; Bogus, Katrina; Burgess, Neil

    2016-09-01

    When remembering the past, we typically recall 'events' that are bounded in time and space. However, as we navigate our environment our senses receive a continuous stream of information. How do we create discrete long-term episodic memories from continuous input? Although previous research has provided evidence for a role of spatial boundaries in the online segmentation of our sensory experience within working memory, it is not known how this segmentation contributes to subsequent long-term episodic memory. Here we show that the presence of a spatial boundary at encoding (a doorway between two rooms) impairs participants' later ability to remember the order that objects were presented in. A sequence of two objects presented in the same room in a virtual reality environment is more accurately remembered than a sequence of two objects presented in adjoining rooms. The results are captured by a simple model in which items are associated to a context representation that changes gradually over time, and changes more rapidly when crossing a spatial boundary. We therefore provide the first evidence that the structure of long-term episodic memory is shaped by the presence of a spatial boundary and provide constraints on the nature of the interaction between working memory and long-term memory. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  1. Spatial distribution of small-leaved forests in Kuznetskaya depression

    Directory of Open Access Journals (Sweden)

    A. F. Gulyaeva

    2016-03-01

    Full Text Available The article is devoted to the spatial distribution of small-leaved forests in Kuznetskaya depression where they are forest component of zonal forest-steppe vegetation. Two levels of spatial organization were determined. According to mesorelief communities of different associations are organized into topo-ecological series. These series differ by length and set of communities. On higher level spatial distribution is controlled by climate and reflects zonal structure. Central part of the depression is occupied by Artemisio–Betuletum communities in combination with communities of Calamagrostio–Betuletum which occur in more humid habitats. Near the eastern edge of the depres­sion forest vegetation is represented by combination of Trollio–Populetum and Campanulo–Betuletum communities where the first one is more typical for the plain conditions and second one – for the mountainous environment. In south­ern part of the depression communities of Campanulo–Betuletum are widespread in combination with Saussureo–Populetum communities which localized on higher well-moisturized slopes. In north-western part syntaxonomical diversity drops down to one association – Primulo–Betuletum, and communities of Carici–Betuletum association occur across the whole depression in lowest relief positions. Climatically it is possible to distinguish two belts – forest-steppe and subtaiga. Forest-steppe is represented by two types – typical plain forest-steppe in north-western part and submountainous forest-steppe in the central part of depression. Subtaiga belt in the depression is developed on eastern edge, but in western part it exists only on mountain slopes.

  2. Experimental measurements of spatial dose distributions in radiosurgery treatments

    International Nuclear Information System (INIS)

    Avila-Rodriguez, M. A.; Rodriguez-Villafuerte, M.; Diaz-Perches, R.; Perez-Pastenes, M. A.

    2001-01-01

    The measurement of stereotactic radiosurgery dose distributions requires an integrating, high-resolution dosimeter capable of providing a spatial map of absorbed dose. This paper describes the use of a commercial radiochromic dye film (GafChromic MD-55-2) to measure radiosurgery dose distributions with 6 MV X-rays in a head phantom. The response of the MD-55-2 was evaluated by digitizing and analyzing the films with conventional computer systems. Radiosurgery dose distributions were measured using the radiochromic film in a spherical acrylic phantom of 16 cm diameter undergoing a typical SRS treatment as a patient, and were compared with dose distributions provided by the treatment planning system. The comparison lead to mean radial differences of ±0.6 mm, ±0.9 mm, ±1.3 mm, ±1.9 mm, and ±2.8 mm, for the 80, 60, 50, 40, and 30% isodose curves, respectively. It is concluded that the radiochromic film is a convenient and useful tool for radiosurgery treatment planning validation

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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...

  9. 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

  10. 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

  11. 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)

  12. 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.

  13. Direct numerical solution of the Ornstein-Zernike integral equation and spatial distribution of water around hydrophobic molecules

    Science.gov (United States)

    Ikeguchi, Mitsunori; Doi, Junta

    1995-09-01

    The Ornstein-Zernike integral equation (OZ equation) has been used to evaluate the distribution function of solvents around solutes, but its numerical solution is difficult for molecules with a complicated shape. This paper proposes a numerical method to directly solve the OZ equation by introducing the 3D lattice. The method employs no approximation the reference interaction site model (RISM) equation employed. The method enables one to obtain the spatial distribution of spherical solvents around solutes with an arbitrary shape. Numerical accuracy is sufficient when the grid-spacing is less than 0.5 Å for solvent water. The spatial water distribution around a propane molecule is demonstrated as an example of a nonspherical hydrophobic molecule using iso-value surfaces. The water model proposed by Pratt and Chandler is used. The distribution agrees with the molecular dynamics simulation. The distribution increases offshore molecular concavities. The spatial distribution of water around 5α-cholest-2-ene (C27H46) is visualized using computer graphics techniques and a similar trend is observed.

  14. Pedestrian count estimation using texture feature with spatial distribution

    Directory of Open Access Journals (Sweden)

    Hongyu Hu

    2016-12-01

    Full Text Available We present a novel pedestrian count estimation approach based on global image descriptors formed from multi-scale texture features that considers spatial distribution. For regions of interest, local texture features are represented based on histograms of multi-scale block local binary pattern, which jointly constitute the feature vector of the whole image. Therefore, to achieve an effective estimation of pedestrian count, principal component analysis is used to reduce the dimension of the global representation features, and a fitting model between image global features and pedestrian count is constructed via support vector regression. The experimental result shows that the proposed method exhibits high accuracy on pedestrian count estimation and can be applied well in the real world.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Detection of endolithic spatial distribution in marble stone.

    Science.gov (United States)

    Casanova Municchia, A; Percario, Z; Caneva, G

    2014-10-01

    The penetration of endolithic microorganisms, which develop to depths of several millimetres or even centimetres into the stone, and the diffusion of their extracellular substances speeds up the stone deterioration process. The aim of this study was to investigate, using a confocal laser scanning microscopy with a double-staining, a marble rock sample by observing the endolithic spatial distribution and quantifying the volume they occupied within the stone, in order to understand the real impact of these microorganisms on the conservation of stone monuments. Often the only factors taken into account by biodeterioration studies regarding endolithic microorganisms, are spread and depth of penetration. Despite the knowledge of three-dimensional spatial distribution and quantification of volume, it is indispensable to understand the real damage caused by endolithic microorganisms to stone monuments. In this work, we analyze a marble rock sample using a confocal laser scanning microscopy stained with propidium iodide and Concavalin-A conjugate with the fluorophore Alexa Fluor 488, comparing these results with other techniques (SEM microscope, microphotographs of polished cross-sections and thin-section, PAS staining methods), An image analysis approach has also been applied. The use of confocal laser scanning microscopy with double staining shows clear evidence of the presence of endolithic microorganisms (cyanobacteria and fungi) as well as the extracellular polymeric substance matrix in a three-dimensional architecture as part of the rock sample, this technique, therefore, seems very useful when applied to restoration interventions on stone monuments when endolithic growth is suspected. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  20. Spatial distribution of conduction disorders during sinus rhythm.

    Science.gov (United States)

    Lanters, Eva A H; Yaksh, Ameeta; Teuwen, Christophe P; van der Does, Lisette J M E; Kik, Charles; Knops, Paul; van Marion, Denise M S; Brundel, Bianca J J M; Bogers, Ad J J C; Allessie, Maurits A; de Groot, Natasja M S

    2017-12-15

    Length of lines of conduction block (CB) during sinus rhythm (SR) at Bachmann's bundle (BB) is associated with atrial fibrillation (AF). However, it is unknown whether extensiveness of CB at BB represents CB elsewhere in the atria. We aim to investigate during SR 1) the spatial distribution and extensiveness of CB 2) whether there is a predilection site for CB and 3) the association between CB and incidence of post-operative AF. During SR, epicardial mapping of the right atrium (RA), BB and left atrium was performed in 209 patients with coronary artery disease. The amount of conduction delay (CD, Δlocal activation time ≥7ms) and CB (Δ≥12ms) was quantified as % of the mapping area. Atrial regions were compared to identify potential predilection sites for CD/CB. Correlations between CD/CB and clinical characteristics were tested. Areas with CD or CB were present in all patients, overall prevalence was respectively 1.4(0.2-4.0) % and 1.3(0.1-4.3) %. Extensiveness and spatial distribution of CD/CB varied considerably, however occurred mainly at the superior intercaval RA. Of all clinicalcharacteristics, CD/CB only correlated weakly with age and diabetes (P<0.05). A 1% increase in CD or CB caused a 1.1-1.5ms prolongation of the activation time (P<0.001). There was no correlation between CD/CB and post-operative AF. CD/CB during SR in CABG patients with electrically non-remodeled atria show considerable intra-atrial, but also inter-individual variation. Despite these differences, a predilection site is present at the superior intercaval RA. Extensiveness of CB at the superior intercaval RA or BB does not reflect CB elsewhere in the atria and is not associated with post-operative AF. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. 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

  2. Mapping the spatial distribution of Aedes aegypti and Aedes albopictus.

    Science.gov (United States)

    Ding, Fangyu; Fu, Jingying; Jiang, Dong; Hao, Mengmeng; Lin, Gang

    2018-02-01

    Mosquito-borne infectious diseases, such as Rift Valley fever, Dengue, Chikungunya and Zika, have caused mass human death with the transnational expansion fueled by economic globalization. Simulating the distribution of the disease vectors is of great importance in formulating public health planning and disease control strategies. In the present study, we simulated the global distribution of Aedes aegypti and Aedes albopictus at a 5×5km spatial resolution with high-dimensional multidisciplinary datasets and machine learning methods Three relatively popular and robust machine learning models, including support vector machine (SVM), gradient boosting machine (GBM) and random forest (RF), were used. During the fine-tuning process based on training datasets of A. aegypti and A. albopictus, RF models achieved the highest performance with an area under the curve (AUC) of 0.973 and 0.974, respectively, followed by GBM (AUC of 0.971 and 0.972, respectively) and SVM (AUC of 0.963 and 0.964, respectively) models. The simulation difference between RF and GBM models was not statistically significant (p>0.05) based on the validation datasets, whereas statistically significant differences (p<0.05) were observed for RF and GBM simulations compared with SVM simulations. From the simulated maps derived from RF models, we observed that the distribution of A. albopictus was wider than that of A. aegypti along a latitudinal gradient. The discriminatory power of each factor in simulating the global distribution of the two species was also analyzed. Our results provided fundamental information for further study on disease transmission simulation and risk assessment. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Self-similar slip distributions on irregular shaped faults

    Science.gov (United States)

    Herrero, A.; Murphy, S.

    2018-06-01

    We propose a strategy to place a self-similar slip distribution on a complex fault surface that is represented by an unstructured mesh. This is possible by applying a strategy based on the composite source model where a hierarchical set of asperities, each with its own slip function which is dependent on the distance from the asperity centre. Central to this technique is the efficient, accurate computation of distance between two points on the fault surface. This is known as the geodetic distance problem. We propose a method to compute the distance across complex non-planar surfaces based on a corollary of the Huygens' principle. The difference between this method compared to others sample-based algorithms which precede it is the use of a curved front at a local level to calculate the distance. This technique produces a highly accurate computation of the distance as the curvature of the front is linked to the distance from the source. Our local scheme is based on a sequence of two trilaterations, producing a robust algorithm which is highly precise. We test the strategy on a planar surface in order to assess its ability to keep the self-similarity properties of a slip distribution. We also present a synthetic self-similar slip distribution on a real slab topography for a M8.5 event. This method for computing distance may be extended to the estimation of first arrival times in both complex 3D surfaces or 3D volumes.

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

    KAUST Repository

    Hyvö nen, Nuutti

    2016-01-01

    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

  5. 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.

  6. 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.

  7. 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.

  8. Structural Constraints On The Spatial Distribution of Aftershocks

    Science.gov (United States)

    McCloskey, J.; Nalbant, S. S.; Steacy, S.; Nostro, C.; Scotti, O.; Baumont, D.

    Real-time, forward modelling of spatial distributions of potentially damaging after- shocks by calculating stress perturbations due to large earthquakes may produce so- cially useful, time- dependent hazard estimates in the foreseeable future. Such calcula- tions, however, rely on the resolution of a stress perturbation tensor (SPT) onto planes whose geometry is unknown and decisions as to the orientations of these planes have a first order effect on the geometry of the resulting hazard distributions. Commonly, these decisions are based on the assumption that structures optimally oriented for fail- ure in the regional stress field, exist everywhere and stress maps are produced by resolving onto these orientations. Here we investigate this proposition using a 3D cal- culation for the optimally oriented planes (OOPs) for the 1992 Landers earthquake (M = 7.3). We examine the encouraged mechanisms as a function of location and show that enhancement for failure exists over a much wider area than in the equivalent, and more usual, 2.5D calculations. Mechanisms predicted in these areas are not consistent with the local structural geology, however, and corresponding aftershocks are gener- ally not observed. We argue that best hazard estimates will result from geometrically restricted versions of the OOP concept in which observed structure constrains possible orientations for failure.

  9. 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 similar spatial distribution patterns mainly governed by geology (parent material and mineralisation), as well as weathering, soil formation and climate since the last glaciations period. The dominant feature is represented by low Mo concentrations over the coarse-grained sandy deposits of the last glaciations in central northern Europe while the most extensive anomalies occur in Scandinavian soils. The highest Mo concentration value occurs to the North of Oslo close to one of the largest porphyry Mo deposit of the World. Some interesting anomalous patterns occur also in Italy in correspondence with alkaline volcanics, in Spain and 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.

  10. Impact of fat mass distribution body shapes on muscles strength and the joints pain

    Directory of Open Access Journals (Sweden)

    Zerf Mohammed

    2016-01-01

    Full Text Available Our study focuses on fat mass distribution body shapes type as measured to determine their effect on skeletal muscle strengthening lumbar extensors (upper and lower limbs where our background confirms that every girl has a natural body type of rectangle, apple, pear, or hourglass. It is good for her to know which type of body shape she is, so she can learn what exercises to do, whereas similar studies suggest that it is much better to challenge weight problems with exercise and dietary measures before resorting to figure shaping. For this purpose, our study was carried out with a total of thirty students, females listed in the Institute of Physical Education and Sport, University of Mostaganem, aged between 20 and 23 years; their homogeneity was based on age, sex, and academic specialty, classified based on the body mass index (BMI into two groups (normal and overweight and based on their body shape′s type into three groups (9 pear shape, 10 rectangle shape, and 11 hourglass shape as a protocol experimental to examine the impact of fat mass distribution body shapes type on lumbar extensor strength. Based on our data analysis, we confirm that the pear and the rectangle shape affect the strength lumbar extensors due to body weight distribution which increases the risks relating to the skeletal muscles. Weight gain is a factor contributing to the weakness of skeletal muscles. However, the body shape explains the anomalies of the distribution of fat mass and BMI risk observed in our sample in the lower and upper part of the body recorded by the values of Killy test and endurance of trunk, the case of the pear and the rectangle shape back pain, which are consisting in excess of the body fat distributed in comparison with less percentage of muscle mass. Whereas this difference can affect the pelvic position.

  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 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

  13. Influence of sawtooth oscillations of fast ion spatial distribution

    International Nuclear Information System (INIS)

    Anderson, D.; Lisak, M.; Wising, F.

    1992-01-01

    Recent measurements of global as well as line integrated neutron emission generated during NBI heating on JET have provided significant information on the influence of sawtooth oscillations on injected ions. The measurements have been analysed tomographically to deduce the spatial distribution of the neutron emission before and after the sawtooth crash, and the results indicate that the fast ions are expelled from the plasma core during crashes. The present report summarizes the theoretical work performed within the JET contract JTI/13435, the final aim of which is to try to interpret the mentioned experimental results. The analysis involves analytical as well as numerical calculations. A new model of sawtooth crashes with q o below unity is presented, based on the models of Kadomtsev and Wesson. The analytical results for the changes in global and local neutron emissivity at the sawtooth crash are in qualitative agreement with experimental results. The new model predicts stronger redistribution of the neutron emissivity, but a smaller change of global emissivity than the Kadomtsev model. A detailed numerical investigation of the sawtooth induced change in neutron emissivity is also made. The Fokker-Planck equation is used to calculate the distribution function of the injected fast ions before the crash and the models are used to find the change of both beam and plasma parameters due to the crash. The radial distributions of the neutron emissivity before and after the crash are then calculated and used for integration along the lines-of-sight of the neutron profile monitor on JET. The flux surface geometry obtained from MHD equilibrium calculations is used during the integration. In addition, the change of the global neutron emission is also calculated and compared with experimental results. Both the Kadomtsev model and the model suggested here are found to be consistent with the experimentally observed change in neutron emissivity provided the q(r)-profile is

  14. 3D shape measurement of moving object with FFT-based spatial matching

    Science.gov (United States)

    Guo, Qinghua; Ruan, Yuxi; Xi, Jiangtao; Song, Limei; Zhu, Xinjun; Yu, Yanguang; Tong, Jun

    2018-03-01

    This work presents a new technique for 3D shape measurement of moving object in translational motion, which finds applications in online inspection, quality control, etc. A low-complexity 1D fast Fourier transform (FFT)-based spatial matching approach is devised to obtain accurate object displacement estimates, and it is combined with single shot fringe pattern prolometry (FPP) techniques to achieve high measurement performance with multiple captured images through coherent combining. The proposed technique overcomes some limitations of existing ones. Specifically, the placement of marks on object surface and synchronization between projector and camera are not needed, the velocity of the moving object is not required to be constant, and there is no restriction on the movement trajectory. Both simulation and experimental results demonstrate the effectiveness of the proposed technique.

  15. 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.

  16. Spatial distribution of carbon sources and sinks in Canada's forests

    International Nuclear Information System (INIS)

    Chen, Jing M.; Weimin, Ju; Liu, Jane; Cihlar, Josef; Chen, Wenjun

    2003-01-01

    Annual spatial distributions of carbon sources and sinks in Canada's forests at 1 km resolution are computed for the period from 1901 to 1998 using ecosystem models that integrate remote sensing images, gridded climate, soils and forest inventory data. GIS-based fire scar maps for most regions of Canada are used to develop a remote sensing algorithm for mapping and dating forest burned areas in the 25 yr prior to 1998. These mapped and dated burned areas are used in combination with inventory data to produce a complete image of forest stand age in 1998. Empirical NPP age relationships were used to simulate the annual variations of forest growth and carbon balance in 1 km pixels, each treated as a homogeneous forest stand. Annual CO 2 flux data from four sites were used for model validation. Averaged over the period 1990-1998, the carbon source and sink map for Canada's forests show the following features: (i) large spatial variations corresponding to the patchiness of recent fire scars and productive forests and (ii) a general south-to-north gradient of decreasing carbon sink strength and increasing source strength. This gradient results mostly from differential effects of temperature increase on growing season length, nutrient mineralization and heterotrophic respiration at different latitudes as well as from uneven nitrogen deposition. The results from the present study are compared with those of two previous studies. The comparison suggests that the overall positive effects of non-disturbance factors (climate, CO 2 and nitrogen) outweighed the effects of increased disturbances in the last two decades, making Canada's forests a carbon sink in the 1980s and 1990s. Comparisons of the modeled results with tower-based eddy covariance measurements of net ecosystem exchange at four forest stands indicate that the sink values from the present study may be underestimated

  17. Mapping the spatial distribution of chloride deposition across Australia

    Science.gov (United States)

    Davies, P. J.; Crosbie, R. S.

    2018-06-01

    The high solubility and conservative behaviour of chloride make it ideal for use as an environmental tracer of water and salt movement through the hydrologic cycle. For such use the spatial distribution of chloride deposition in rainfall at a suitable scale must be known. A number of authors have used point data acquired from field studies of chloride deposition around Australia to construct relationships to characterise chloride deposition as a function of distance from the coast; these relationships have allowed chloride deposition to be interpolated in different regions around Australia. In this paper we took this a step further and developed a chloride deposition map for all of Australia which includes a quantification of uncertainty. A previously developed four parameter model of chloride deposition as a function of distance from the coast for Australia was used as the basis for producing a continental scale chloride deposition map. Each of the four model parameters were made spatially variable by creating parameter surfaces that were interpolated using a pilot point regularisation approach within a parameter estimation software. The observations of chloride deposition were drawn from a literature review that identified 291 point measurements of chloride deposition over a period of 80 years spread unevenly across all Australian States and Territories. A best estimate chloride deposition map was developed from the resulting surfaces on a 0.05 degree grid. The uncertainty in the chloride deposition map was quantified as the 5th and 95th percentile of 1000 calibrated models produced via Null Space Monte Carlo analysis and the spatial variability of chloride deposition across the continent was consistent with landscape morphology. The temporal variability in chloride deposition on a decadal scale was investigated in the Murray-Darling Basin, this highlighted the need for long-term monitoring of chloride deposition if the uncertainty of the continental scale map is

  18. 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.

  19. 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.

  20. Spatial Distribution of Stable Isotopes of Precipitation in Kumamoto, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Anoue, M. T.; Shimada, J. [Graduate School of Science and Technology, Kumamoto University (Japan); Ichiyanagi, K. [Graduate School of Science and Technology, Kumamoto University and Japan Agency for Marine-Earth Science and Technology (Japan)

    2013-07-15

    To understand the spatial distribution of stable isotopic compositions in precipitation, precipitation samples were collected every two weeks from november 2009 to december 2010 at 6 points in Kumamoto, Japan. The {delta}{sup 18}O and {delta}{sup 2}H of precipitation samples were measured by isotope ratio mass spectrometry (Delta-S) with CO{sub 2}/H2{sub O} equivalent method for {delta}{sup 18}O and the chromium reduction method for {delta}2H. The range of {delta}{sup 18}O and d-excess (= {delta}{sup 2}H - 8 {delta}{sup 18}O) in precipitation is from -13.4 per mille to -3.5 per mille and from 2.6 per mille to 35.6 per mille , respectively. Seasonal variability of {delta}{sup 18}O (d-excess) in precipitation was low (high) in winter and high (low) in summer. The seasonal wind of this study area was dominated by south-westerly in summer (from June to August) and north-westerly in winter (from December to February). These wind regimes indicate seasonal variabilities of the water vapour pathway from the origin. In this paper the trend of inland effect to the {delta}{sup 18}O for both south-westerly and north-westerly are also considered. As a result, significant correlation between distances from the coastal line at south-westerly or north-westerly and {delta}{sup 18}O in precipitation was recognized, particularly from 18 February to 7 March and from 29 September to 19 October in 2010 (statistically significant with 5% level). Furthermore, in order to evaluate the course of precipitation, the column total of water vapour flux was considered in the whole period by using JRA-25 and JCDAS. It is interesting that the inland effect corresponded to the column total of water vapour flux at south-westerly (north-westerly). Hence, it is conceivable that the spatial distribution of {delta}{sup 18}O in precipitation was controlled by a column total of water vapour flux in this area. (author)

  1. Metabolic and demographic feedbacks shape the emergent spatial structure and function of microbial communities.

    Directory of Open Access Journals (Sweden)

    Sylvie Estrela

    Full Text Available Microbes are predominantly found in surface-attached and spatially structured polymicrobial communities. Within these communities, microbial cells excrete a wide range of metabolites, setting the stage for interspecific metabolic interactions. The links, however, between metabolic and ecological interactions (functional relationships, and species spatial organization (structural relationships are still poorly understood. Here, we use an individual-based modelling framework to simulate the growth of a two-species surface-attached community where food (resource is traded for detoxification (service and investigate how metabolic constraints of individual species shape the emergent structural and functional relationships of the community. We show that strong metabolic interdependence drives the emergence of mutualism, robust interspecific mixing, and increased community productivity. Specifically, we observed a striking and highly stable emergent lineage branching pattern, generating a persistent lineage mixing that was absent when the metabolic exchange was removed. These emergent community properties are driven by demographic feedbacks, such that aid from neighbouring cells directly enhances focal cell growth, which in turn feeds back to neighbour fecundity. In contrast, weak metabolic interdependence drives conflict (exploitation or competition, and in turn greater interspecific segregation. Together, these results support the idea that species structural and functional relationships represent the net balance of metabolic interdependencies.

  2. 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.

  3. 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.

  4. Modeling of Subsurface Lagrangian Sensor Swarms for Spatially Distributed Current Measurements in High Energy Coastal Environments

    Science.gov (United States)

    Harrison, T. W.; Polagye, B. L.

    2016-02-01

    Coastal ecosystems are characterized by spatially and temporally varying hydrodynamics. In marine renewable energy applications, these variations strongly influence project economics and in oceanographic studies, they impact accuracy of biological transport and pollutant dispersion models. While stationary point or profile measurements are relatively straight forward, spatial representativeness of point measurements can be poor due to strong gradients. Moving platforms, such as AUVs or surface vessels, offer better coverage, but suffer from energetic constraints (AUVs) and resolvable scales (vessels). A system of sub-surface, drifting sensor packages is being developed to provide spatially distributed, synoptic data sets of coastal hydrodynamics with meter-scale resolution over a regional extent of a kilometer. Computational investigation has informed system parameters such as drifter size and shape, necessary position accuracy, number of drifters, and deployment methods. A hydrodynamic domain with complex flow features was created using a computational fluid dynamics code. A simple model of drifter dynamics propagate the drifters through the domain in post-processing. System parameters are evaluated relative to their ability to accurately recreate domain hydrodynamics. Implications of these results for an inexpensive, depth-controlled Lagrangian drifter system is presented.

  5. 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

  6. 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

  7. Formation and spatial distribution of hypervelocity stars in AGN outflows

    Science.gov (United States)

    Wang, Xiawei; Loeb, Abraham

    2018-05-01

    We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

  8. Adaptive spatial filtering for daytime satellite quantum key distribution

    Science.gov (United States)

    Gruneisen, Mark T.; Sickmiller, Brett A.; Flanagan, Michael B.; Black, James P.; Stoltenberg, Kurt E.; Duchane, Alexander W.

    2014-11-01

    The rate of secure key generation (SKG) in quantum key distribution (QKD) is adversely affected by optical noise and loss in the quantum channel. In a free-space atmospheric channel, the scattering of sunlight into the channel can lead to quantum bit error ratios (QBERs) sufficiently large to preclude SKG. Furthermore, atmospheric turbulence limits the degree to which spatial filtering can reduce sky noise without introducing signal losses. A system simulation quantifies the potential benefit of tracking and higher-order adaptive optics (AO) technologies to SKG rates in a daytime satellite engagement scenario. The simulations are performed assuming propagation from a low-Earth orbit (LEO) satellite to a terrestrial receiver that includes an AO system comprised of a Shack-Hartmann wave-front sensor (SHWFS) and a continuous-face-sheet deformable mirror (DM). The effects of atmospheric turbulence, tracking, and higher-order AO on the photon capture efficiency are simulated using statistical representations of turbulence and a time-domain waveoptics hardware emulator. Secure key generation rates are then calculated for the decoy state QKD protocol as a function of the receiver field of view (FOV) for various pointing angles. The results show that at FOVs smaller than previously considered, AO technologies can enhance SKG rates in daylight and even enable SKG where it would otherwise be prohibited as a consequence of either background optical noise or signal loss due to turbulence effects.

  9. Channel-facilitated molecular transport: The role of strength and spatial distribution of interactions

    Energy Technology Data Exchange (ETDEWEB)

    Uppulury, Karthik, E-mail: karthik.uppulury@gmail.com [Department of Chemistry, Texas Tech University, Lubbock, TX 79409 (United States); Kolomeisky, Anatoly B. [Department of Chemistry, Department of Chemical and Biomolecular Engineering, Center for Theoretical Biological Physics, Rice University, Houston, TX 77005 (United States)

    2016-12-20

    Highlights: • Molecular flux strongly depends on the strength of the molecule-pore interactions. • There exists an optimal molecule-pore interaction potential for maximal flux. • Volume of interactions depends inversely on the strength for maximal flux. • Stronger interactions need more number of attractive sites for maximal flux. • Channels with few special sites need more attractive sites for higher flux. - Abstract: Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.

  10. Channel-facilitated molecular transport: The role of strength and spatial distribution of interactions

    International Nuclear Information System (INIS)

    Uppulury, Karthik; Kolomeisky, Anatoly B.

    2016-01-01

    Highlights: • Molecular flux strongly depends on the strength of the molecule-pore interactions. • There exists an optimal molecule-pore interaction potential for maximal flux. • Volume of interactions depends inversely on the strength for maximal flux. • Stronger interactions need more number of attractive sites for maximal flux. • Channels with few special sites need more attractive sites for higher flux. - Abstract: Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.

  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. 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.

  13. Spatially Different Tissue-Scale Diffusivity Shapes ANGUSTIFOLIA3 Gradient in Growing Leaves.

    Science.gov (United States)

    Kawade, Kensuke; Tanimoto, Hirokazu; Horiguchi, Gorou; Tsukaya, Hirokazu

    2017-09-05

    The spatial gradient of signaling molecules is pivotal for establishing developmental patterns of multicellular organisms. It has long been proposed that these gradients could arise from the pure diffusion process of signaling molecules between cells, but whether this simplest mechanism establishes the formation of the tissue-scale gradient remains unclear. Plasmodesmata are unique channel structures in plants that connect neighboring cells for molecular transport. In this study, we measured cellular- and tissue-scale kinetics of molecular transport through plasmodesmata in Arabidopsis thaliana developing leaf primordia by fluorescence recovery assays. These trans-scale measurements revealed biophysical properties of diffusive molecular transport through plasmodesmata and revealed that the tissue-scale diffusivity, but not the cellular-scale diffusivity, is spatially different along the leaf proximal-to-distal axis. We found that the gradient in cell size along the developmental axis underlies this spatially different tissue-scale diffusivity. We then asked how this diffusion-based framework functions in establishing a signaling gradient of endogenous molecules. ANGUSTIFOLIA3 (AN3) is a transcriptional co-activator, and as we have shown here, it forms a long-range signaling gradient along the leaf proximal-to-distal axis to determine a cell-proliferation domain. By genetically engineering AN3 mobility, we assessed each contribution of cell-to-cell movement and tissue growth to the distribution of the AN3 gradient. We constructed a diffusion-based theoretical model using these quantitative data to analyze the AN3 gradient formation and demonstrated that it could be achieved solely by the diffusive molecular transport in a growing tissue. Our results indicate that the spatially different tissue-scale diffusivity is a core mechanism for AN3 gradient formation. This provides evidence that the pure diffusion process establishes the formation of the long-range signaling

  14. 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

  15. Hair mercury levels in Amazonian populations: spatial distribution and trends

    Directory of Open Access Journals (Sweden)

    Barbieri Flavia L

    2009-12-01

    Full Text Available Abstract Background Mercury is present in the Amazonian aquatic environments from both natural and anthropogenic sources. As a consequence, many riverside populations are exposed to methylmercury, a highly toxic organic form of mercury, because of their intense fish consumption. Many studies have analysed this exposure from different approaches since the early nineties. This review aims to systematize the information in spatial distribution, comparing hair mercury levels by studied population and Amazonian river basin, looking for exposure trends. Methods The reviewed papers were selected from scientific databases and online libraries. We included studies with a direct measure of hair mercury concentrations in a sample size larger than 10 people, without considering the objectives, approach of the study or mercury speciation. The results are presented in tables and maps by river basin, displaying hair mercury levels and specifying the studied population and health impact, if any. Results The majority of the studies have been carried out in communities from the central Amazonian regions, particularly on the Tapajós River basin. The results seem quite variable; hair mercury means range from 1.1 to 34.2 μg/g. Most studies did not show any significant difference in hair mercury levels by gender or age. Overall, authors emphasized fish consumption frequency as the main risk factor of exposure. The most studied adverse health effect is by far the neurological performance, especially motricity. However, it is not possible to conclude on the relation between hair mercury levels and health impact in the Amazonian situation because of the relatively small number of studies. Conclusions Hair mercury levels in the Amazonian regions seem to be very heterogenic, depending on several factors. There is no obvious spatial trend and there are many areas that have never been studied. Taking into account the low mercury levels currently handled as acceptable, the

  16. The spatial distribution and evolution characteristics of North Atlantic cyclones

    Science.gov (United States)

    Dacre, H.; Gray, S.

    2009-09-01

    Mid-latitude cyclones play a large role in determining the day-to-day weather conditions in western Europe through their associated wind and precipitation patterns. Thus, their typical spatial and evolution characteristics are of great interest to meteorologists, insurance and risk management companies. In this study a feature tracking algorithm is applied to a cyclone database produced using the Hewson-method of cyclone identification, based on low-level gradients of wet-bulb potential temperature, to produce a climatology of mid-latitude cyclones. The aim of this work is to compare the cyclone track and density statistics found in this study with previous climatologies and to determine reasons for any differences. This method is found to compare well with other cyclone identification methods; the north Atlantic storm track is reproduced along with the major regions of genesis. Differences are attributed to cyclone lifetime and strength thresholds, dataset resolution and cyclone identification and tracking methods. Previous work on cyclone development has been largely limited to case studies as opposed to analysis of climatological data, and does not distinguish between the different stages of cyclone evolution. The cyclone database used in this study allows cyclone characteristics to be tracked throughout the cyclone lifecycle. This enables the evaluation of the characteristics of cyclone evolution for systems forming in different genesis regions and a calculation of the spatial distribution and evolution of these characteristics in composite cyclones. It was found that most of the cyclones that cross western Europe originate in the east Atlantic where the baroclinicity and sea surface temperature gradients are weak compared to the west Atlantic. East Atlantic cyclones also have higher low-level relative vorticity and lower mean sea level pressure at their genesis point than west Atlantic cyclones. This is consistent with the hypothesis that they are secondary

  17. Analysing the distribution of synaptic vesicles using a spatial point process model

    DEFF Research Database (Denmark)

    Khanmohammadi, Mahdieh; Waagepetersen, Rasmus; Nava, Nicoletta

    2014-01-01

    functionality by statistically modelling the distribution of the synaptic vesicles in two groups of rats: a control group subjected to sham stress and a stressed group subjected to a single acute foot-shock (FS)-stress episode. We hypothesize that the synaptic vesicles have different spatial distributions...... in the two groups. The spatial distributions are modelled using spatial point process models with an inhomogeneous conditional intensity and repulsive pairwise interactions. Our results verify the hypothesis that the two groups have different spatial distributions....

  18. 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

  19. 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.

  20. Learning efficient visual search for stimuli containing diagnostic spatial configurations and color-shape conjunctions.

    Science.gov (United States)

    Reavis, Eric A; Frank, Sebastian M; Tse, Peter U

    2018-04-12

    Visual search is often slow and difficult for complex stimuli such as feature conjunctions. Search efficiency, however, can improve with training. Search for stimuli that can be identified by the spatial configuration of two elements (e.g., the relative position of two colored shapes) improves dramatically within a few hundred trials of practice. Several recent imaging studies have identified neural correlates of this learning, but it remains unclear what stimulus properties participants learn to use to search efficiently. Influential models, such as reverse hierarchy theory, propose two major possibilities: learning to use information contained in low-level image statistics (e.g., single features at particular retinotopic locations) or in high-level characteristics (e.g., feature conjunctions) of the task-relevant stimuli. In a series of experiments, we tested these two hypotheses, which make different predictions about the effect of various stimulus manipulations after training. We find relatively small effects of manipulating low-level properties of the stimuli (e.g., changing their retinotopic location) and some conjunctive properties (e.g., color-position), whereas the effects of manipulating other conjunctive properties (e.g., color-shape) are larger. Overall, the findings suggest conjunction learning involving such stimuli might be an emergent phenomenon that reflects multiple different learning processes, each of which capitalizes on different types of information contained in the stimuli. We also show that both targets and distractors are learned, and that reversing learned target and distractor identities impairs performance. This suggests that participants do not merely learn to discriminate target and distractor stimuli, they also learn stimulus identity mappings that contribute to performance improvements.

  1. Real-time distribution of pelagic fish: combining hydroacoustics, GIS and spatial modelling at a fine spatial scale.

    Science.gov (United States)

    Muška, Milan; Tušer, Michal; Frouzová, Jaroslava; Mrkvička, Tomáš; Ricard, Daniel; Seďa, Jaromír; Morelli, Federico; Kubečka, Jan

    2018-03-29

    Understanding spatial distribution of organisms in heterogeneous environment remains one of the chief issues in ecology. Spatial organization of freshwater fish was investigated predominantly on large-scale, neglecting important local conditions and ecological processes. However, small-scale processes are of an essential importance for individual habitat preferences and hence structuring trophic cascades and species coexistence. In this work, we analysed the real-time spatial distribution of pelagic freshwater fish in the Římov Reservoir (Czechia) observed by hydroacoustics in relation to important environmental predictors during 48 hours at 3-h interval. Effect of diurnal cycle was revealed of highest significance in all spatial models with inverse trends between fish distribution and predictors in day and night in general. Our findings highlighted daytime pelagic fish distribution as highly aggregated, with general fish preferences for central, deep and highly illuminated areas, whereas nighttime distribution was more disperse and fish preferred nearshore steep sloped areas with higher depth. This turnover suggests prominent movements of significant part of fish assemblage between pelagic and nearshore areas on a diel basis. In conclusion, hydroacoustics, GIS and spatial modelling proved as valuable tool for predicting local fish distribution and elucidate its drivers, which has far reaching implications for understanding freshwater ecosystem functioning.

  2. Spatial Distribution of Hydrologic Ecosystem Service Estimates: Comparing Two Models

    Science.gov (United States)

    Dennedy-Frank, P. J.; Ghile, Y.; Gorelick, S.; Logsdon, R. A.; Chaubey, I.; Ziv, G.

    2014-12-01

    We compare estimates of the spatial distribution of water quantity provided (annual water yield) from two ecohydrologic models: the widely-used Soil and Water Assessment Tool (SWAT) and the much simpler water models from the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) toolbox. These two models differ significantly in terms of complexity, timescale of operation, effort, and data required for calibration, and so are often used in different management contexts. We compare two study sites in the US: the Wildcat Creek Watershed (2083 km2) in Indiana, a largely agricultural watershed in a cold aseasonal climate, and the Upper Upatoi Creek Watershed (876 km2) in Georgia, a mostly forested watershed in a temperate aseasonal climate. We evaluate (1) quantitative estimates of water yield to explore how well each model represents this process, and (2) ranked estimates of water yield to indicate how useful the models are for management purposes where other social and financial factors may play significant roles. The SWAT and InVEST models provide very similar estimates of the water yield of individual subbasins in the Wildcat Creek Watershed (Pearson r = 0.92, slope = 0.89), and a similar ranking of the relative water yield of those subbasins (Spearman r = 0.86). However, the two models provide relatively different estimates of the water yield of individual subbasins in the Upper Upatoi Watershed (Pearson r = 0.25, slope = 0.14), and very different ranking of the relative water yield of those subbasins (Spearman r = -0.10). The Upper Upatoi watershed has a significant baseflow contribution due to its sandy, well-drained soils. InVEST's simple seasonality terms, which assume no change in storage over the time of the model run, may not accurately estimate water yield processes when baseflow provides such a strong contribution. Our results suggest that InVEST users take care in situations where storage changes are significant.

  3. 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.

  4. On the spatial and temporal distribution of global thunderstorm cells

    International Nuclear Information System (INIS)

    Mezuman, Keren; Price, Colin; Galanti, Eli

    2014-01-01

    Estimates of global thunderstorm activity have been made predominately by direct measurements of lightning discharges around the globe, either by optical measurements from satellites, or using ground-based radio antennas. In this paper we propose a new methodology in which thunderstorm clusters are constructed based on the lightning strokes detected by the World Wide Lightning Location Network (WWLLN) in the very low frequency range. We find that even with low lightning detection efficiency on a global scale, the spatial and temporal distribution of global thunderstorm cells is well reproduced. This is validated by comparing the global diurnal variations of the thunderstorm cells, and the currents produced by these storms, with the well-known Carnegie Curve, which represents the mean diurnal variability of the global atmospheric electric circuit, driven by thunderstorm activity. While the Carnegie Curve agrees well with our diurnal thunderstorm cluster variations, there is little agreement between the Carnegie Curve and the diurnal variation in the number of lightning strokes detected by the WWLLN. When multiplying the number of clusters we detect by the mean thunderstorm conduction current for land and ocean thunderstorms (Mach et al 2011 J. Geophys. Res. 116 D05201) we get a total average current of about 760 A. Our results show that thunderstorms alone explain more than 90% in the variability of the global electric circuit. However, while it has been previously shown that 90% of the global lightning occurs over continental landmasses, we show that around 50% of the thunderstorms are over the oceans, and from 00-09UTC there are more thunderstorm cells globally over the oceans than over the continents. Since the detection efficiency of the WWLLN system has increased over time, we estimate that the lower bound of the mean number of global thunderstorm cells in 2012 was around 1050 per hour, varying from around 840 at 03UTC to 1150 storms at 19UTC. (letter)

  5. 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

  6. Spatial Data Exploring by Satellite Image Distributed Processing

    Science.gov (United States)

    Mihon, V. D.; Colceriu, V.; Bektas, F.; Allenbach, K.; Gvilava, M.; Gorgan, D.

    2012-04-01

    Our society needs and environmental predictions encourage the applications development, oriented on supervising and analyzing different Earth Science related phenomena. Satellite images could be explored for discovering information concerning land cover, hydrology, air quality, and water and soil pollution. Spatial and environment related data could be acquired by imagery classification consisting of data mining throughout the multispectral bands. The process takes in account a large set of variables such as satellite image types (e.g. MODIS, Landsat), particular geographic area, soil composition, vegetation cover, and generally the context (e.g. clouds, snow, and season). All these specific and variable conditions require flexible tools and applications to support an optimal search for the appropriate solutions, and high power computation resources. The research concerns with experiments on solutions of using the flexible and visual descriptions of the satellite image processing over distributed infrastructures (e.g. Grid, Cloud, and GPU clusters). This presentation highlights the Grid based implementation of the GreenLand application. The GreenLand application development is based on simple, but powerful, notions of mathematical operators and workflows that are used in distributed and parallel executions over the Grid infrastructure. Currently it is used in three major case studies concerning with Istanbul geographical area, Rioni River in Georgia, and Black Sea catchment region. The GreenLand application offers a friendly user interface for viewing and editing workflows and operators. The description involves the basic operators provided by GRASS [1] library as well as many other image related operators supported by the ESIP platform [2]. The processing workflows are represented as directed graphs giving the user a fast and easy way to describe complex parallel algorithms, without having any prior knowledge of any programming language or application commands

  7. Temporal and spatial distribution characteristics in the natural plague foci of Chinese Mongolian gerbils based on spatial autocorrelation.

    Science.gov (United States)

    Du, Hai-Wen; Wang, Yong; Zhuang, Da-Fang; Jiang, Xiao-San

    2017-08-07

    The nest flea index of Meriones unguiculatus is a critical indicator for the prevention and control of plague, which can be used not only to detect the spatial and temporal distributions of Meriones unguiculatus, but also to reveal its cluster rule. This research detected the temporal and spatial distribution characteristics of the plague natural foci of Mongolian gerbils by body flea index from 2005 to 2014, in order to predict plague outbreaks. Global spatial autocorrelation was used to describe the entire spatial distribution pattern of the body flea index in the natural plague foci of typical Chinese Mongolian gerbils. Cluster and outlier analysis and hot spot analysis were also used to detect the intensity of clusters based on geographic information system methods. The quantity of M. unguiculatus nest fleas in the sentinel surveillance sites from 2005 to 2014 and host density data of the study area from 2005 to 2010 used in this study were provided by Chinese Center for Disease Control and Prevention. The epidemic focus regions of the Mongolian gerbils remain the same as the hot spot regions relating to the body flea index. High clustering areas possess a similar pattern as the distribution pattern of the body flea index indicating that the transmission risk of plague is relatively high. In terms of time series, the area of the epidemic focus gradually increased from 2005 to 2007, declined rapidly in 2008 and 2009, and then decreased slowly and began trending towards stability from 2009 to 2014. For the spatial change, the epidemic focus regions began moving northward from the southwest epidemic focus of the Mongolian gerbils from 2005 to 2007, and then moved from north to south in 2007 and 2008. The body flea index of Chinese gerbil foci reveals significant spatial and temporal aggregation characteristics through the employing of spatial autocorrelation. The diversity of temporary and spatial distribution is mainly affected by seasonal variation, the human

  8. The dynamics of sensory buffers: geometric, spatial, and experience-dependent shaping of iconic memory.

    Science.gov (United States)

    Graziano, Martin; Sigman, Mariano

    2008-05-23

    When a stimulus is presented, its sensory trace decays rapidly, lasting for approximately 1000 ms. This brief and labile memory, referred as iconic memory, serves as a buffer before information is transferred to working memory and executive control. Here we explored the effect of different factors--geometric, spatial, and experience--with respect to the access and the maintenance of information in iconic memory and the progressive distortion of this memory. We studied performance in a partial report paradigm, a design wherein recall of only part of a stimulus array is required. Subjects had to report the identity of a letter in a location that was cued in a variable delay after the stimulus onset. Performance decayed exponentially with time, and we studied the different parameters (time constant, zero-delay value, and decay amplitude) as a function of the different factors. We observed that experience (determined by letter frequency) affected the access to iconic memory but not the temporal decay constant. On the contrary, spatial position affected the temporal course of delay. The entropy of the error distribution increased with time reflecting a progressive morphological distortion of the iconic buffer. We discuss our results on the context of a model of information access to executive control and how it is affected by learning and attention.

  9. Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

    International Nuclear Information System (INIS)

    Churmakov, D Y; Meglinski, I V; Piletsky, S A; Greenhalgh, D A

    2003-01-01

    A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an 'effective' depth

  10. Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Churmakov, D Y [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Meglinski, I V [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Piletsky, S A [Institute of BioScience and Technology, Cranfield University, Silsoe, MK45 4DT (United Kingdom); Greenhalgh, D A [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom)

    2003-07-21

    A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an 'effective' depth.

  11. Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

    Science.gov (United States)

    Y Churmakov, D.; Meglinski, I. V.; Piletsky, S. A.; Greenhalgh, D. A.

    2003-07-01

    A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an `effective' depth.

  12. Spatial fluxes and energy distributions of reactor fast neutrons in two types of heat resistant concretes

    International Nuclear Information System (INIS)

    Akki, T.S.; Benayad, S.A.; Megahid, R.M.

    1992-01-01

    Measurements have been carried out to study the spatial fluxes and energy distributions of reactor fast neutrons transmitted through two types of heat resistant concretes, serpentine concrete and magnetic lemonite concrete. The physical, chemical and mechanical properties of these concretes were checked by well known techniques. In addition, the effect of heating at temperatures up to 500deg C on the crystaline water content was checked by the method of differential thermal analysis. Measurements were performed using a collimated beam of reactor neutrons emitted from a 10 MW research reactor. The neutron spectra transmitted through concrete barriers of different thickness were measured by a scintillation spectrometer with NE-213 liquid organic scintillator. Discrimination against undesired pulses due to gamma-rays was achieved by a method based on pulse shape discrimination technique. The operating principle of this technique is based on the comparison of two weighted time integrals of the detector signal. The measured pulse amplitude distribution was converted to neutron energy distribution by a computational code based on double differentiation technique. The spectrometer workability and the accuracy of the unfolding technique were checked by measuring the neutron spectra of neutrons from Pu-α-Be and 252 Cf neutron sources. The obtained neutron spectra for the two concretes were used to derive the total cross sections for neutrons of different energies. (orig.)

  13. 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 ...

  14. Automatic generation of 3D statistical shape models with optimal landmark distributions.

    Science.gov (United States)

    Heimann, T; Wolf, I; Meinzer, H-P

    2007-01-01

    To point out the problem of non-uniform landmark placement in statistical shape modeling, to present an improved method for generating landmarks in the 3D case and to propose an unbiased evaluation metric to determine model quality. Our approach minimizes a cost function based on the minimum description length (MDL) of the shape model to optimize landmark correspondences over the training set. In addition to the standard technique, we employ an extended remeshing method to change the landmark distribution without losing correspondences, thus ensuring a uniform distribution over all training samples. To break the dependency of the established evaluation measures generalization and specificity from the landmark distribution, we change the internal metric from landmark distance to volumetric overlap. Redistributing landmarks to an equally spaced distribution during the model construction phase improves the quality of the resulting models significantly if the shapes feature prominent bulges or other complex geometry. The distribution of landmarks on the training shapes is -- beyond the correspondence issue -- a crucial point in model construction.

  15. Spatial distribution pattern of vanadium in hydric landscapes

    Science.gov (United States)

    Fiedler, Sabine; Breuer, Jörn; Palmer, Iris; Berger, Jochen

    2010-05-01

    landscapes. Independent from the parent material, we found a distinct spatial pattern of V, which reflected that of the local redox environment: Horizons/pedons with oxic conditions revealed a positive correlation between V content and Fe content. In this case, iron oxides act as an important sink for dissolved V which originated from other locations of the catena. Poorly drained soils, such as Stagnosols for example, promote both Fe and V reduction, which is coupled to their removal from the pedons by leaching. It can be demonstrated that the element-specific Eh window for differential reduction is very narrow. The spatial distribution of both elements shows that high V contents are often associated with low Fe contents. It is therefore assumed that a reducing environment promotes Fe3+ reduction, while maintaining while maintaining V stable.

  16. 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....

  17. 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

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

    African Journals Online (AJOL)

    This paper therefore analyzed the spatial patterns of healthcare facilities in Akwa ... Data on six health indicator variables were obtained and analyzed to assess ... of healthcare facilities and thus hinders good access to high quality healthcare ...

  19. 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.

  20. SPATIAL VARIETY AND DISTRIBUTION OF TRADITIONAL MARKETS IN SURAKARTA AS POTENTIAL FACTORS IN IMPROVING SPATIAL-BASED MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Istijabatul Aliyah

    2017-02-01

    Full Text Available Traditional markets function as trading place, socio-culture interaction, and recreation facility either in regional or urban scope. Distribution and variety of spatial condition influence traditional markets’ planning both physically and non-physically. Therefore, this research aimed to conduct a mapping of traditional markets’ spatial distribution and variety as potential factors to improve spatial-based management. Analysis methods including: (1 Mapping by employing Geographic Information System, (2 Category Based Analysis (CBA, and (3 Interactive Analysis were applied in Surakarta City as the research location. The result of this research signifies that spatial variety and distribution of traditional markets in Surakarta had similar pattern between one market to others; overlapping service function; specific commodity types in accordance with the market’s characteristics; diverse operating hours. Spatial variety and distribution could be potential factors to improve traditional market management as shopping service. This result was contrasted with Central Place Theory by Christaller and NÆss & Jensen’s research finding stating that distance became a key factor influencing accessibility to a number of activity facilities. Therefore, distance toward the service center is not considered as the main factor in traditional market management. The main factor in managing and controlling traditional markets’ development includes service function, commodity specification, and operating hour’s flexibility.

  1. Determination of size and shape distributions of metal and ceramic powders

    International Nuclear Information System (INIS)

    Jovanovic, DI.

    1961-01-01

    For testing the size and shape distributions of metal and ceramic uranium oxide powders the following method for analysing the grain size of powders were developed and implemented: microscopic analysis and sedimentation method. A gravimetry absorption device was constructed for determining the specific surfaces of powders

  2. 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.

  3. 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.

  4. 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.

  5. Generalised extreme value distributions provide a natural hypothesis for the shape of seed mass distributions.

    Directory of Open Access Journals (Sweden)

    Will Edwards

    Full Text Available Among co-occurring species, values for functionally important plant traits span orders of magnitude, are uni-modal, and generally positively skewed. Such data are usually log-transformed "for normality" but no convincing mechanistic explanation for a log-normal expectation exists. Here we propose a hypothesis for the distribution of seed masses based on generalised extreme value distributions (GEVs, a class of probability distributions used in climatology to characterise the impact of event magnitudes and frequencies; events that impose strong directional selection on biological traits. In tests involving datasets from 34 locations across the globe, GEVs described log10 seed mass distributions as well or better than conventional normalising statistics in 79% of cases, and revealed a systematic tendency for an overabundance of small seed sizes associated with low latitudes. GEVs characterise disturbance events experienced in a location to which individual species' life histories could respond, providing a natural, biological explanation for trait expression that is lacking from all previous hypotheses attempting to describe trait distributions in multispecies assemblages. We suggest that GEVs could provide a mechanistic explanation for plant trait distributions and potentially link biology and climatology under a single paradigm.

  6. 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

  7. 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.

  8. 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.

  9. Spatial distribution of H II regions in NGC 4321

    International Nuclear Information System (INIS)

    Anderson, S.; Hodge, P.; Kennicutt, R.C. Jr.

    1983-01-01

    A catalog of 286 H II regions in the giant Sc Virgo Cluster spiral galaxy NGC 4321 is used to analyze some aspects of this galaxy's spiral structure. The H II region distribution is rectified to face-on by least-squares fitting to a logarithmic spiral, and the radial distribution, the across-arm distribution, and the along-arm distribution of H II regions are determined. Comparison of the circular distribution with a simple shock wave model of the density wave theory does not clearly support the model. Arm 1 shows no obvious structure, and arm 2, although it has a clear peak, does not show the expected asymmetrical distribution. Agreement is reasonably good, however, with the somewhat more elaborate density wave model of Bash. Tests for clumping of the H II regions were negative

  10. Calculation of spatial distribution of the EURACOS II converter source

    International Nuclear Information System (INIS)

    Santo, A.C.F. de

    1985-01-01

    It is obtained the neutron spatial flux from the EURACOS (Enriched Uranium Converter Source) device, adjusted to experimental measures. The EURACOS device is a converter source which is constituted a circle plate of highly enriched uranium (90%). The converter provides an intense source of fast neutrons which has the energetic spectrum near to the fission spectrum. (M.C.K.) [pt

  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. Design of a collector shape for uniform flow distribution in microchannels

    International Nuclear Information System (INIS)

    Siddique, Ayyaz; Agrawal, Amit; Saha, Sandip K; Medhi, Bhaskar J; Singh, Anugrah

    2017-01-01

    The focus of this study is the design of a collector with the objective of achieving uniform flow in multiple parallel microchannels. This objective is achieved by understanding the limitations of current designs and a novel design is proposed, which is further carefully optimized. The existing collector shape considered is U-type, which is investigated numerically. The creation of a stagnation zone, growth of a boundary layer along the collector wall and low/high velocity zones in the collector are identified as the prime causes of flow maldistribution. A novel design, a dumbbell shape collector, is proposed to overcome the limitations of the earlier designs. The dumbbell shape is evaluated quantitatively and is found to perform better than all existing shapes. This dumbbell shape collector provides a uniform flow distribution with less than 0.4% relative difference from the average flow rate in different channels, which is substantially better than existing collectors with 2.3% relative difference from the average flow rate for Re ch   =  32. The uniformity is further confirmed using micro-particle image velocimetry measurements. The dumbbell shape collector is generalized and optimized to cater to heat sinks of different dimensions and to broaden its applicability in both micro and macro dimensions. (paper)

  13. 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.

  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. 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

    /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.......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...

  16. 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

    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......, 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...... with discrete time processes in the setting of the present paper as well as other spatial-temporal situations....

  17. 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

  18. Thematic and spatial resolutions affect model-based predictions of tree species distribution.

    Science.gov (United States)

    Liang, Yu; He, Hong S; Fraser, Jacob S; Wu, ZhiWei

    2013-01-01

    Subjective decisions of thematic and spatial resolutions in characterizing environmental heterogeneity may affect the characterizations of spatial pattern and the simulation of occurrence and rate of ecological processes, and in turn, model-based tree species distribution. Thus, this study quantified the importance of thematic and spatial resolutions, and their interaction in predictions of tree species distribution (quantified by species abundance). We investigated how model-predicted species abundances changed and whether tree species with different ecological traits (e.g., seed dispersal distance, competitive capacity) had different responses to varying thematic and spatial resolutions. We used the LANDIS forest landscape model to predict tree species distribution at the landscape scale and designed a series of scenarios with different thematic (different numbers of land types) and spatial resolutions combinations, and then statistically examined the differences of species abundance among these scenarios. Results showed that both thematic and spatial resolutions affected model-based predictions of species distribution, but thematic resolution had a greater effect. Species ecological traits affected the predictions. For species with moderate dispersal distance and relatively abundant seed sources, predicted abundance increased as thematic resolution increased. However, for species with long seeding distance or high shade tolerance, thematic resolution had an inverse effect on predicted abundance. When seed sources and dispersal distance were not limiting, the predicted species abundance increased with spatial resolution and vice versa. Results from this study may provide insights into the choice of thematic and spatial resolutions for model-based predictions of tree species distribution.

  19. 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.

  20. 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

  1. 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

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

    Science.gov (United States)

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

    2016-11-05

    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 600mm (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. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Sediment spatial distribution evaluated by three methods and its relation to some soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Bacchi, O O.S. . [Centro de Energia Nuclear na Agricultura-CENA/USP, Laboratorio de Fisica do Solo, Piracicaba, SP (Brazil); Reichardt, K [Centro de Energia Nuclear na Agricultura-CENA/USP, Laboratorio de Fisica do Solo, Piracicaba, SP (Brazil); Departamento de Ciencias Exatas, Escola Superior de Agricultura ' Luiz de Queiroz' ESALQ/USP, Piracicaba, SP (Brazil); Sparovek, G [Departamento de Solos e Nutricao de Plantas, Escola Superior de Agricultura ' Luiz de Queiroz' ESALQ/USP, Piracicaba, SP (Brazil)

    2003-02-15

    An investigation of rates and spatial distribution of sediments on an agricultural field cultivated with sugarcane was undertaken using the {sup 137}Cs technique, USLE and WEPP models. The study was carried out on the Ceveiro watershed of the Piracicaba river basin, state of Sao Paulo, Brazil, experiencing severe soil degradation due to soil erosion. The objectives of the study were to compare the spatial distribution of sediments evaluated by the three methods and its relation to some soil properties. Erosion and sedimentation rates and their spatial distribution estimated by the three methods were completely different. Although not able to show sediment deposition, the spatial distribution of erosion rates evaluated by USLE presented the best correlation with other studied soil properties. (author)

  9. 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...

  10. Coloniality of birds in the Kalahari – spatial distribution of trees and nests of the Sociable Weaver (Philetairus socius)

    CSIR Research Space (South Africa)

    Rösner, S

    2010-01-01

    Full Text Available The spatial distribution of suitable nest sites is a limiting resource for many colonial breeding animals. Therefore, we investigated and mapped the spatial distribution of nests of Sociable Weaver (Philetairus socius) to evaluate whether the size...

  11. 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 ...

  12. 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...

  13. 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

  14. Single-server queues with spatially distributed arrivals

    NARCIS (Netherlands)

    Kroese, Dirk; Schmidt, Volker

    1994-01-01

    Consider a queueing system where customers arrive at a circle according to a homogeneous Poisson process. After choosing their positions on the circle, according to a uniform distribution, they wait for a single server who travels on the circle. The server's movement is modelled by a Brownian motion

  15. Spatial distribution of China׳s renewable energy industry

    DEFF Research Database (Denmark)

    Dong, Liang; Liang, Hanwei; Gao, Zhiqiu

    2016-01-01

    , 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...

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

    African Journals Online (AJOL)

    Cultivation of Bt crops is an important tactic in integrated pest management. The effect of Bt maize on arthropod predators needs to be investigated because of the important role of these natural enemies in the absence of target pests. The objective of the present study was to generate information on the distribution model of ...

  17. 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.

  18. Reactivity effect of spent fuel due to spatial distributions for coolant temperature and burnup

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, T.; Yamane, Y. [Nagoya Univ., Dept. of Nuclear Engineering, Nagoya, Aichi (Japan); Suyama, K. [OECD/NEA, Paris (France); Mochizuki, H. [Japan Research Institute, Ltd., Tokyo (Japan)

    2002-03-01

    We investigated the reactivity effect of spent fuel caused by the spatial distributions of coolant temperature and burnup by using the integrated burnup calculation code system SWAT. The reactivity effect which arises from taking account of the spatial coolant temperature distribution increases as the average burnup increases, and reaches the maximum value of 0.69%{delta}k/k at 50 GWd/tU when the burnup distribution is concurrently considered. When the burnup distribution is ignored, the reactivity effect decreases by approximately one-third. (author)

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

    KAUST Repository

    Balzer, Jonathan

    2011-01-01

    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

  20. 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

  1. 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

  2. Spatial distribution of Madeira Island Laurisilva endemic spiders (Arachnida: Araneae)

    Science.gov (United States)

    2014-01-01

    Abstract Madeira island presents a unique spider diversity with a high number of endemic species, many of which are still poorly known. A recent biodiversity survey on the terrestrial arthropods of the native forest, Laurisilva, provided a large set of standardized samples from various patches throughout the island. Out of the fifty two species recorded, approximately 33.3% are Madeiran endemics, many of which had not been collected since their original description. Two new species to science are reported – Ceratinopsis n. sp. and Theridion n. sp. – and the first records of Poeciloneta variegata (Blackwall, 1841) and Tetragnatha intermedia Kulczynski, 1891 are reported for the first time for Madeira island. Considerations on species richness and abundance from different Laurisilva locations are presented, together with distribution maps for endemic species. These results contribute to a better understanding of spider diversity patterns and endemic species distribution in the native forest of Madeira island. PMID:24855443

  3. Statistical analysis of the spatial distribution of galaxies and clusters

    International Nuclear Information System (INIS)

    Cappi, Alberto

    1993-01-01

    This thesis deals with the analysis of the distribution of galaxies and clusters, describing some observational problems and statistical results. First chapter gives a theoretical introduction, aiming to describe the framework of the formation of structures, tracing the history of the Universe from the Planck time, t_p = 10"-"4"3 sec and temperature corresponding to 10"1"9 GeV, to the present epoch. The most usual statistical tools and models of the galaxy distribution, with their advantages and limitations, are described in chapter two. A study of the main observed properties of galaxy clustering, together with a detailed statistical analysis of the effects of selecting galaxies according to apparent magnitude or diameter, is reported in chapter three. Chapter four delineates some properties of groups of galaxies, explaining the reasons of discrepant results on group distributions. Chapter five is a study of the distribution of galaxy clusters, with different statistical tools, like correlations, percolation, void probability function and counts in cells; it is found the same scaling-invariant behaviour of galaxies. Chapter six describes our finding that rich galaxy clusters too belong to the fundamental plane of elliptical galaxies, and gives a discussion of its possible implications. Finally chapter seven reviews the possibilities offered by multi-slit and multi-fibre spectrographs, and I present some observational work on nearby and distant galaxy clusters. In particular, I show the opportunities offered by ongoing surveys of galaxies coupled with multi-object fibre spectrographs, focusing on the ESO Key Programme A galaxy redshift survey in the south galactic pole region to which I collaborate and on MEFOS, a multi-fibre instrument with automatic positioning. Published papers related to the work described in this thesis are reported in the last appendix. (author) [fr

  4. The spatial distribution and birth-rate of pulsars

    International Nuclear Information System (INIS)

    Guseinov, O.H.; Kasumov, F.K.

    1978-01-01

    The distribution of pulsars in the wide range of observed luminosities has been obtained. It is shown that the function of luminosity (FL) within 3 x 10 26 30 erg s -1 conforms to the power law dN/dL - c 1 Lsup(-γ), where γ = 1.76 +- 0.06. For L 26 erg s -1 , FL changes its inclination and may be approximated as dN/dL approximately Lsup(-γ 1 ), where γ 1 = 0.7 +- 0.2. On the basis of statistical selection, including all pulsars with L > 3 x 10 28 erg s -1 , the distribution of pulsars has been investigated as a function of the distance to the centre R and galactic plane Z. The obtained laws of the radial and Z-distribution of pulsars and galactic supernova remnants and also the radial distribution of types I and II supernovae in the models Sb and Sc support the hypothesis of their origin from the objects of the flat subsystem of Population I. Since there are some arguments in favour of a possible connection between supernovae I and the objects of the intermediate component of the Galaxy, one cannot exclude the possibility of supernovae explosions at the end of the evolution of stars with masses of 1.5-2 Msub(sun). It is also shown that pulsars and supernovae are evidently objects that are connected genetically, and, within the limits of statistical error, they have a similar birth-rate. The empirical law of the evolution of a pulsar's luminosity as a function of its true age has been obtained, according to which L = c 2 tsup(-β), where c 2 = (3.69+- 3.4) x 10 35 ,β = 1.32 +- 0.11. (Auth.)

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

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Gyldenkærne, Steen

    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...... 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...

  6. Analyse de la distribution spatiale des Acanthaceae en Afrique ...

    African Journals Online (AJOL)

    Sci-Nat

    d'échantillons sont: Justicia Lin. avec 1595 échantillons (17,1% des échantillons; 58 espèces), Thunbergia Retz avec 813 échantillons. (8,7% des échantillons; 36 espèces), et. Asystasia Blume avec 638 échantillons (6,8% des échantillons; 11 espèces). La carte de distribution des. 9181 échantillons d'Acanthaceae (Fig.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. Disease spread across multiple scales in a spatial hierarchy: effect of host spatial structure and of inoculum quantity and distribution.

    Science.gov (United States)

    Gosme, Marie; Lucas, Philippe

    2009-07-01

    Spatial patterns of both the host and the disease influence disease spread and crop losses. Therefore, the manipulation of these patterns might help improve control strategies. Considering disease spread across multiple scales in a spatial hierarchy allows one to capture important features of epidemics developing in space without using explicitly spatialized variables. Thus, if the system under study is composed of roots, plants, and planting hills, the effect of host spatial pattern can be studied by varying the number of plants per planting hill. A simulation model based on hierarchy theory was used to simulate the effects of large versus small planting hills, low versus high level of initial infections, and aggregated versus uniform distribution of initial infections. The results showed that aggregating the initially infected plants always resulted in slower epidemics than spreading out the initial infections uniformly. Simulation results also showed that, in most cases, disease epidemics were slower in the case of large host aggregates (100 plants/hill) than with smaller aggregates (25 plants/hill), except when the initially infected plants were both numerous and spread out uniformly. The optimal strategy for disease control depends on several factors, including initial conditions. More importantly, the model offers a framework to account for the interplay between the spatial characteristics of the system, rates of infection, and aggregation of the disease.

  13. Spatial distribution of errors associated with multistatic meteor radar

    Science.gov (United States)

    Hocking, W. K.

    2018-06-01

    With the recent increase in numbers of small and versatile low-power meteor radars, the opportunity exists to benefit from simultaneous application of multiple systems spaced by only a few hundred km and less. Transmissions from one site can be recorded at adjacent receiving sites using various degrees of forward scatter, potentially allowing atmospheric conditions in the mesopause regions between stations to be diagnosed. This can allow a better spatial overview of the atmospheric conditions at any time. Such studies have been carried out using a small version of such so-called multistatic meteor radars, e.g. Chau et al. (Radio Sci 52:811-828, 2017, https://doi.org/10.1002/2016rs006225 ). These authors were able to also make measurements of vorticity and divergence. However, measurement uncertainties arise which need to be considered in any application of such techniques. Some errors are so severe that they prohibit useful application of the technique in certain locations, particularly for zones at the midpoints of the radars sites. In this paper, software is developed to allow these errors to be determined, and examples of typical errors involved are discussed. The software should be of value to others who wish to optimize their own MMR systems.

  14. Shape Distributions of Nonlinear Dynamical Systems for Video-Based Inference.

    Science.gov (United States)

    Venkataraman, Vinay; Turaga, Pavan

    2016-12-01

    This paper presents a shape-theoretic framework for dynamical analysis of nonlinear dynamical systems which appear frequently in several video-based inference tasks. Traditional approaches to dynamical modeling have included linear and nonlinear methods with their respective drawbacks. A novel approach we propose is the use of descriptors of the shape of the dynamical attractor as a feature representation of nature of dynamics. The proposed framework has two main advantages over traditional approaches: a) representation of the dynamical system is derived directly from the observational data, without any inherent assumptions, and b) the proposed features show stability under different time-series lengths where traditional dynamical invariants fail. We illustrate our idea using nonlinear dynamical models such as Lorenz and Rossler systems, where our feature representations (shape distribution) support our hypothesis that the local shape of the reconstructed phase space can be used as a discriminative feature. Our experimental analyses on these models also indicate that the proposed framework show stability for different time-series lengths, which is useful when the available number of samples are small/variable. The specific applications of interest in this paper are: 1) activity recognition using motion capture and RGBD sensors, 2) activity quality assessment for applications in stroke rehabilitation, and 3) dynamical scene classification. We provide experimental validation through action and gesture recognition experiments on motion capture and Kinect datasets. In all these scenarios, we show experimental evidence of the favorable properties of the proposed representation.

  15. Macroscopic electrical field distribution and field-induced surface stresses of needle-shaped field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Moy, Charles K.S., E-mail: charles.moy@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); ARC Centre of Excellence for Design in Light Metals, The University of Sydney, Sydney, NSW 2006 (Australia); School of Civil Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Ranzi, Gianluca [ARC Centre of Excellence for Design in Light Metals, The University of Sydney, Sydney, NSW 2006 (Australia); School of Civil Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Petersen, Timothy C. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); Ringer, Simon P. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); ARC Centre of Excellence for Design in Light Metals, The University of Sydney, Sydney, NSW 2006 (Australia)

    2011-05-15

    One major concern since the development of the field ion microscope is the mechanical strength of the specimens. The macroscopic shape of the imaging tip greatly influences field-induced stresses and there is merit in further study of this phenomenon from a classical perspective. Understanding the geometrical, as opposed to localized electronic, factors that affect the stress might improve the quality and success rate of atom probe experiments. This study uses macroscopic electrostatic principles and finite element modelling to investigate field-induced stresses in relation to the shape of the tip. Three two-dimensional idealized models are considered, namely hyperbolic, parabolic and sphere-on-orthogonal-cone; the shapes of which are compared to experimental tips prepared by electro-polishing. Three dimensional morphologies of both a nano-porous and single-crystal aluminium tip are measured using electron tomography to quantitatively test the assumption of cylindrical symmetry for electro-polished tips. The porous tip was prepared and studied to demonstrate a fragile specimen for which such finite element studies could determine potential mechanical failure, prior to any exhaustive atom probe investigation. -- Research highlights: {yields} We use electrostatic principles and finite element to model field-induced stresses. {yields} We study two-dimensional idealized needle-shaped field emitters. {yields} Stress distribution of hyperbolic, parabolic and sphere-on-orthogonal-cone tips mapped. {yields} Electron tomography to obtain the morphology of three-dimensional aluminium tips. {yields} Studies of the morphology of the porous tip demonstrate a fragile specimen.

  16. 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.

  17. Measurement-Based Spatial Correlation and Capacity of Indoor Distributed MIMO System

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2013-01-01

    Full Text Available Distributed MIMO (D-MIMO system is one of the candidates for future wireless access networks. In this study, the spatial correlation and capacity in indoor D-MIMO system are presented. All results are from the actual channel measurements in typical indoor scenarios, including office and corridor. Based on measured data, spatial correlation coefficients between distributed transmitting antennas are analyzed. Although the literature about D-MIMO system assumes the small scale fading between distributed antennas is independent, we find that spatial correlation may still exist in specific propagation scenario. This correlation can also degrade the performance of D-MIMO system. To mitigate the impact of spatial correlation, one efficient method is to use transmitting antenna selection technique.

  18. 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

  19. Local host specialization, host-switching, and dispersal shape the regional distributions of avian haemosporidian parasites.

    Science.gov (United States)

    Ellis, Vincenzo A; Collins, Michael D; Medeiros, Matthew C I; Sari, Eloisa H R; Coffey, Elyse D; Dickerson, Rebecca C; Lugarini, Camile; Stratford, Jeffrey A; Henry, Donata R; Merrill, Loren; Matthews, Alix E; Hanson, Alison A; Roberts, Jackson R; Joyce, Michael; Kunkel, Melanie R; Ricklefs, Robert E

    2015-09-08

    The drivers of regional parasite distributions are poorly understood, especially in comparison with those of free-living species. For vector-transmitted parasites, in particular, distributions might be influenced by host-switching and by parasite dispersal with primary hosts and vectors. We surveyed haemosporidian blood parasites (Plasmodium and Haemoproteus) of small land birds in eastern North America to characterize a regional parasite community. Distributions of parasite populations generally reflected distributions of their hosts across the region. However, when the interdependence between hosts and parasites was controlled statistically, local host assemblages were related to regional climatic gradients, but parasite assemblages were not. Moreover, because parasite assemblage similarity does not decrease with distance when controlling for host assemblages and climate, parasites evidently disperse readily within the distributions of their hosts. The degree of specialization on hosts varied in some parasite lineages over short periods and small geographic distances independently of the diversity of available hosts and potentially competing parasite lineages. Nonrandom spatial turnover was apparent in parasite lineages infecting one host species that was well-sampled within a single year across its range, plausibly reflecting localized adaptations of hosts and parasites. Overall, populations of avian hosts generally determine the geographic distributions of haemosporidian parasites. However, parasites are not dispersal-limited within their host distributions, and they may switch hosts readily.

  20. Fiber Bragg grating based spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples

    International Nuclear Information System (INIS)

    Latka, Ines; Habisreuther, Tobias; Litzkendorf, Doris

    2011-01-01

    Highlights: → Fiber Bragg gratings (FBG) act as strain sensors, also at cryogenic temperatures. → FBGs are not sensitive to magnetic fields. → Local, shape dependent magnetostriction was detected on rectangular samples. → Magnetostrictive effects of the top surface and in a gap between two samples are different. - Abstract: We report on measurements of the spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples. The spatially resolved strain measurements are accomplished by the use 2 fiber Bragg grating arrays, which are with an included angle of 45 o fixed to the surface. In this paper first attempts to confirm the shape distortions caused by the flux-pinning induced strain as predicted in will be presented. Two sample setups, a single bulk and a 'mirror' arrangement, will be compared. This mirror setup represents a model configuration for a measurement inside the superconductor, where demagnetization effects can be neglected and the magnetic field merely has a z-component.

  1. Spatial and temporal distribution of singlet oxygen in Lake Superior.

    Science.gov (United States)

    Peterson, Britt M; McNally, Ann M; Cory, Rose M; Thoemke, John D; Cotner, James B; McNeill, Kristopher

    2012-07-03

    A multiyear field study was undertaken on Lake Superior to investigate singlet oxygen ((1)O(2)) photoproduction. Specifically, trends within the lake were examined, along with an assessment of whether correlations existed between chromophoric dissolved organic matter (CDOM) characteristics and (1)O(2) production rates and quantum yields. Quantum yield values were determined and used to estimate noontime surface (1)O(2) steady-state concentrations ([(1)O(2)](ss)). Samples were subdivided into three categories based on their absorbance properties (a300): riverine, river-impacted, or open lake sites. Using calculated surface [(1)O(2)](ss), photochemical half-lives under continuous summer sunlight were calculated for cimetidine, a pharmaceutical whose reaction with (1)O(2) has been established, to be on the order of hours, days, and a week for the riverine, river-impacted, and open lake waters, respectively. Of the CDOM properties investigated, it was found that dissolved organic carbon (DOC) and a300 were the best parameters for predicting production rates of [(1)O(2)](ss). For example, given the correlations found, one could predict [(1)O(2)](ss) within a factor of 4 using a300 alone. Changes in the quantum efficiency of (1)O(2) production upon dilution of river water samples with lake water samples demonstrated that the CDOM found in the open lake is not simply diluted riverine organic matter. The open lake pool was characterized by low absorption coefficient, low fluorescence, and low DOC, but more highly efficient (1)O(2) production and predominates the Lake Superior system spatially. This study establishes that parameters that reflect the quantity of CDOM (e.g., a300 and DOC) correlate with (1)O(2) production rates, while parameters that characterize the absorbance spectrum (e.g., spectral slope coefficient and E2:E3) correlate with (1)O(2) production quantum yields.

  2. 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

  3. 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

  4. 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.

  5. 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)

  6. 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

  7. 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.

  8. 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.

  9. The experimental method of measurement for spatial distribution of full aperture backscatter light by circular PIN-array

    International Nuclear Information System (INIS)

    Zhao Xuefeng; Wang Chuanke; Hu Feng; Kuang Longyu; Wang Zhebin; Li Sanwei; Liu Shengye; Jiang Gang

    2011-01-01

    The spatial distribution of backscatter light is very important for understanding the production of backscatter light. The experimental method of spatial distribution of full aperture backscatter light is based on the circular PIN array composed of concentric orbicular multi-PIN detectors. The image of backscatter light spatial distribution of full aperture SBS is obtained by measuring spatial distribution of full aperture backscatter light using the method in the experiment of laser hohlraum targets interaction at 'Shenguang II'. A preliminary method to measure spatial distribution of full aperture backscatter light is established. (authors)

  10. Spatial distribution and morphometry of permafrost-related landforms in the Central Pyrenees

    Science.gov (United States)

    Fernandes, Marcelo; Oliva, Marc; Lopes, Luís; Ruiz-Fernández, Jesus; Palma, Pedro; Pereira, Paulo

    2017-04-01

    Present and past permafrost distribution in the Pyrenees is still under discussion. As in other mid-latitude mountain regions, rock glaciers and protalus lobes are the min indicators of permafrost conditions. In this study, we examine the distribution of these landforms in the Boí valley, a formerly glaciated U-shaped valley ranging from 850 to 3000 m a.s.l. The valley encompasses a surface of 247 km2, mainly composed of granite and shales. The spatial distribution of rock glaciers and protalus lobes and their chronostratigraphic position within the valley allow a better understanding of the climatic and environmental conditions necessary for their development. Geomorphological mapping of these landforms was built using high resolution imagery provided by the Institut Cartogràfic i Geologic de Catalunya, complemented with Basemap ESRI images and Google Earth Pro, and subsequently improved with field observations. The map was generated in a GIS environment following the RCP 77 mapping system of the Centre National de la Recherche Scientifique (CNRS) (Joly, 1997). Several parameters of each landform have been measured (Table 1): area (ha), altitude (maximum, minimum, mean), length (L), width (W), aspect and slope. This information provides accurate characterization of the morphometric properties of these landforms as well as a detailed identification of their spatial distribution. Up to 121 permafrost-related landforms were identified in the Boí valley, including 84 rock glaciers and 37 protalus lobes. Most of the landforms (93% for rock glaciers and 95% for protalus lobes) are located inside the glacial cirques, while the rest is distributed in the valley bottom or slopes of the formerly glaciated valleys. The lowest elevation of both forms is situated at 2100 m a.s.l. Therefore, this altitude may be indicative of the lowest level recording permafrost conditions during the period in which these landforms formed. The maximum elevation of the landforms usually

  11. 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

  12. 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.

  13. 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...... to interpret data on N2O emissions following a uniform or layered amendment of manure to agricultural soil. The spatial distribution of O2 and gas emission rates were monitored for 12 h. An anoxic layer formed rapidly around the layered manure, whereas the uniformly distributed manure led to a more widespread...... 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...

  14. Effect of Contour Shape of Nervous System Electromagnetic Stimulation Coils on the Induced Electrical Field Distribution

    Directory of Open Access Journals (Sweden)

    Daskalov Ivan K

    2002-05-01

    Full Text Available Abstract Background Electromagnetic stimulation of the nervous system has the advantage of reduced discomfort in activating nerves. For brain structures stimulation, it has become a clinically accepted modality. Coil designs usually consider factors such as optimization of induced power, focussing, field shape etc. In this study we are attempting to find the effect of the coil contour shape on the electrical field distribution for magnetic stimulation. Method and results We use the maximum of the induced electric field stimulation in the region of interest as the optimization criterion. This choice required the application of the calculus of variation, with the contour perimeter taken as a pre-set condition. Four types of coils are studied and compared: circular, square, triangular and an 'optimally' shaped contour. The latter yields higher values of the induced electrical field in depths up to about 30 mm, but for depths around 100 mm, the circular shape has a slight advantage. The validity of the model results was checked by experimental measurements in a tank with saline solution, where differences of about 12% were found. In view the accuracy limitations of the computational and measurement methods used, such differences are considered acceptable. Conclusion We applied an optimization approach, using the calculus of variation, which allows to obtain a coil contour shape corresponding to a selected criterion. In this case, the optimal contour showed higher intensities for a longer line along the depth-axis. The method allows modifying the induced field structure and focussing the field to a selected zone or line.

  15. Spatial Distribution of Nitrogen on Grazed Karst Landscapes

    Directory of Open Access Journals (Sweden)

    Douglas G. Boyer

    2001-01-01

    Full Text Available The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian region. Karst areas comprise about 18% of the region’s land area. An estimated one-third of the region’s farms, cattle, and agricultural market value are located on karst terrain. Mean nitrate concentrations in several karst springs in southeastern West Virginia exhibit a strong linear relationship with the percentage of agriculture land cover. Development of best management practices for efficient nitrogen (N use and reduction of outflow of N to water from karst areas requires knowledge about N dynamics on those landscapes. Water extractable NO3-N and NH4-N were measured along transects at four soil depths in two grazed sinkholes and one wooded sinkhole. Distribution of soil NO3-N and NH4-N were related to frequency of animal presence and to topographic and hydrologic redistribution of soil and fecal matter in the grazed sinkholes. Karst pastures are characterized by under drainage and funneling of water and contaminants to the shallow aquifer. Control of NO3-N leaching from karst pasture may depend on management strategies that change livestock grazing behavior in sinkholes and reduce the opportunity for water and contaminants to quickly reach sinkhole drains.

  16. Potassium availability in soils - forms and spatial distribution

    International Nuclear Information System (INIS)

    Afari-Sefa, Victor; Kwakye, Peter K.; Nyamiah, Mercy; Okae-Anti, Daniel; Imoro, A. Ziblim

    2004-10-01

    Potassium forms the third most important plant nutrient limiting plant growth and consequently reducing crop yields. This study was conducted on soil potassium availability, distribution and relationship with other soil properties. Seventeen top soil samples (0-15 cm) were collected from four agro-ecological zones of the Central and Western Regions of Ghana. Water soluble, exchangeable and non-exchangeable forms of K were determined. The exchangeable K was extracted with 1 N-bar NH 4 OAc, 0.1 N-bar HNO 3 , 0.01 M-bar CaCl 2 , Bray No. 1 and 1 N-bar boiling HNO 3 . The non-exchangeable K was extracted with 1 N-bar boiling HNO 3 . Potassium was determined using flame photometer. The results showed that potassium is available in the soil in different forms and amounts. Soils from the forest-savanna transition and coastal savanna zones had relatively higher soil solution K concentration than soils from the moist rainforest and semi-deciduous forest zones. Also, soils of the semi-deciduous forest and forest savanna transition as well as the coastal savanna zones contained 2-3 times exchangeable K of the soils of the moist rainforest. The results also showed that the pH, texture as well as the land use affected K availability in the soils. (author)

  17. 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.

  18. Spatial distribution of dust in galaxies from the Integral field unit data

    Science.gov (United States)

    Zafar, Tayyaba; Sophie Dubber, Andrew Hopkins

    2018-01-01

    An important characteristic of the dust is it can be used as a tracer of stars (and gas) and tell us about the composition of galaxies. Sub-mm and infrared studies can accurately determine the total dust mass and its spatial distribution in massive, bright galaxies. However, faint and distant galaxies are hampered by resolution to dust spatial dust distribution. In the era of integral-field spectrographs (IFS), Balmer decrement is a useful quantity to infer the spatial extent of the dust in distant and low-mass galaxies. We conducted a study to estimate the spatial distribution of dust using the Sydney-Australian Astronomical Observatory (AAO) Multi-object Integral field spectrograph (SAMI) galaxies. Our methodology is unique to exploit the potential of IFS and using the spatial and spectral information together to study dust in galaxies of various morphological types. The spatial extent and content of dust are compared with the star-formation rate, reddening, and inclination of galaxies. We find a right correlation of dust spatial extent with the star-formation rate. The results also indicate a decrease in dust extent radius from Late Spirals to Early Spirals.

  19. Comparison of alternative spatial resolutions in the application of a spatially distributed biogeochemical model over complex terrain

    Science.gov (United States)

    Turner, D.P.; Dodson, R.; Marks, D.

    1996-01-01

    Spatially distributed biogeochemical models may be applied over grids at a range of spatial resolutions, however, evaluation of potential errors and loss of information at relatively coarse resolutions is rare. In this study, a georeferenced database at the 1-km spatial resolution was developed to initialize and drive a process-based model (Forest-BGC) of water and carbon balance over a gridded 54976 km2 area covering two river basins in mountainous western Oregon. Corresponding data sets were also prepared at 10-km and 50-km spatial resolutions using commonly employed aggregation schemes. Estimates were made at each grid cell for climate variables including daily solar radiation, air temperature, humidity, and precipitation. The topographic structure, water holding capacity, vegetation type and leaf area index were likewise estimated for initial conditions. The daily time series for the climatic drivers was developed from interpolations of meteorological station data for the water year 1990 (1 October 1989-30 September 1990). Model outputs at the 1-km resolution showed good agreement with observed patterns in runoff and productivity. The ranges for model inputs at the 10-km and 50-km resolutions tended to contract because of the smoothed topography. Estimates for mean evapotranspiration and runoff were relatively insensitive to changing the spatial resolution of the grid whereas estimates of mean annual net primary production varied by 11%. The designation of a vegetation type and leaf area at the 50-km resolution often subsumed significant heterogeneity in vegetation, and this factor accounted for much of the difference in the mean values for the carbon flux variables. Although area wide means for model outputs were generally similar across resolutions, difference maps often revealed large areas of disagreement. Relatively high spatial resolution analyses of biogeochemical cycling are desirable from several perspectives and may be particularly important in the

  20. 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.

  1. Inferring the flood frequency distribution for an ungauged basin using a spatially distributed rainfall-runoff model

    Directory of Open Access Journals (Sweden)

    G. Moretti

    2008-08-01

    Full Text Available The estimation of the peak river flow for ungauged river sections is a topical issue in applied hydrology. Spatially distributed rainfall-runoff models can be a useful tool to this end, since they are potentially able to simulate the river flow at any location of the watershed drainage network. However, it is not fully clear to what extent these models can provide reliable simulations over a wide range of spatial scales. This issue is investigated here by applying a spatially distributed, continuous simulation rainfall-runoff model to infer the flood frequency distribution of the Riarbero River. This is an ungauged mountain creek located in northern Italy, whose drainage area is 17 km2. The hydrological model is first calibrated by using a 1-year record of hourly meteorological data and river flows observed at the outlet of the 1294 km2 wide Secchia River basin, of which the Riarbero is a tributary. The model is then validated by performing a 100-year long simulation of synthetic river flow data, which allowed us to compare the simulated and observed flood frequency distributions at the Secchia River outlet and the internal cross river section of Cavola Bridge, where the basin area is 337 km2. Finally, another simulation of hourly river flows was performed by referring to the outlet of the Riarbero River, therefore allowing us to estimate the related flood frequency distribution. The results were validated by using estimates of peak river flow obtained by applying hydrological similarity principles and a regional method. The results show that the flood flow estimated through the application of the distributed model is consistent with the estimate provided by the regional procedure as well as the behaviors of the river banks. Conversely, the method based on hydrological similarity delivers an estimate that seems to be not as reliable. The analysis highlights interesting perspectives for the application of

  2. 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/

  3. 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.

  4. 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 modulator Maweza, Elijah L Gailele, Lucas M Strauss, Hencharl J Litvin, Ihar Forbes, Andrew Dudley, Angela L ABSTRACT: We demonstrate the operation and calibration of a spatial light modulator in the mid-IR region by creating and measuring...

  5. Spatial distribution of ciguateric fish in the Republic of Kiribati.

    Science.gov (United States)

    Chan, Wing Hei; Mak, Yim Ling; Wu, Jia Jun; Jin, Ling; Sit, Wai Hung; Lam, James Chung Wah; Sadovy de Mitcheson, Yvonne; Chan, Leo Lai; Lam, Paul Kwan Sing; Murphy, Margaret B

    2011-06-01

    Ciguatera is food poisoning caused by human consumption of reef fish contaminated with ciguatoxins (CTXs). The expanding international trade of tropical fish species from ciguatera-endemic regions has resulted in increased global incidence of ciguatera, and more than 50000 people are estimated to suffer from ciguatera each year worldwide. The Republic of Kiribati is located in the Pacific Ocean; two of its islands, Marakei and Tarawa, have been suggested as high-risk areas for ciguatera. The toxicities of coral reef fish collected from these islands, including herbivorous, omnivorous and carnivorous fish (24% [n=41], 8% [n=13] and 68% [n=117], respectively), were analyzed using the mouse neuroblastoma assay (MNA) after CTX extraction. The MNA results indicated that 156 fish specimens, or 91% of the fish samples, were ciguatoxic (CTX levels >0.01 ng g(-1)). Groupers and moray eels were generally more toxic by an order of magnitude than other fish species. All of the collected individuals of eight species (n=3-19) were toxic. Toxicity varied within species and among locations by up to 10000-fold. Cephalapholis argus and Gymnothorax spp. collected from Tarawa Island were significantly less toxic than those from Marakei Island, although all individuals were toxic based on the 0.01 ng g(-1) threshold. CTX concentrations in the livers of individuals of two moray eel species (Gymnothorax spp., n=6) were nine times greater than those in muscle, and toxicity in liver and muscle showed a strong positive correlation with body weight. The present study provides quantitative information on the ciguatoxicity and distribution of toxicity in fish for use in fisheries management and public health. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. 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

  7. 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.

  8. Spatial and temporal distribution of fungicides applied to creeping bentgrass.

    Science.gov (United States)

    Hockemeyer, Kurt R; Latin, Richard

    2015-05-01

    Turf managers often rely on fungicides to limit damage caused by root diseases. Because fungicides are applied to aboveground surfaces and do not move basipetally, they are effective against root pathogens only when fungitoxic concentrations migrate to the rhizosphere. This research focused on the distribution of modern fungicides in verdure, thatch, sand, and roots of creeping bentgrass [ L. var. (Huds.) Farw.] maintained as a putting green. The fungicides azoxystrobin (methyl (E)-2-[2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate), propiconazole (1,2,4-triazole, 1-((2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl)methyl), pyraclostrobin (carbamic acid, [2-[[[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy]methyl]phenyl]methoxy-,methyl ester), and thiophanate-methyl (dimethyl 4,'4-o-phenylenebis[3-thioallophanate]) were applied to replicate field plots in a water volume of 815 L ha. Plots were sampled at 0, 3, 7, 10, 14, 17, and 21 d after application by extracting cores measuring 1.9 cm in diameter by 3.8 cm deep. Cores were separated into verdure/thatch, sand, and roots before quantitative determination (liquid chromatography, triple quadrupole mass spectrometry) of fungicide residues. Fungicide residues in verdure/thatch declined steadily with time and support previously reported results describing fungicide depletion. Fungicides were detected in roots and sand within 5 h of application at very low (1-15 mg kg) concentrations and remained at low levels throughout the sampling period. Fungicides differed with respect to amounts recovered per turfgrass component. Azoxystrobin and propiconazole were associated with roots for the duration of the experiment, but pyraclostrobin was nearly undetectable. Near-zero levels of all fungicides were detected in the sand component. Half-life values in the verdure/thatch component ranged from 2.3 to 18.9 d. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of

  9. 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.

  10. Benefits of incorporating spatial organisation of catchments for a semi-distributed hydrological model

    Science.gov (United States)

    Schumann, Andreas; Oppel, Henning

    2017-04-01

    To represent the hydrological behaviour of catchments a model should reproduce/reflect the hydrologically most relevant catchment characteristics. These are heterogeneously distributed within a watershed but often interrelated and subject of a certain spatial organisation. Since common models are mostly based on fundamental assumptions about hydrological processes, the reduction of variance of catchment properties as well as the incorporation of the spatial organisation of the catchment is desirable. We have developed a method that combines the idea of the width-function used for determination of the geomorphologic unit hydrograph with information about soil or topography. With this method we are able to assess the spatial organisation of selected catchment characteristics. An algorithm was developed that structures a watershed into sub-basins and other spatial units to minimise its heterogeneity. The outcomes of this algorithm are used for the spatial setup of a semi-distributed model. Since the spatial organisation of a catchment is not bound to a single characteristic, we have to embed information of multiple catchment properties. For this purpose we applied a fuzzy-based method to combine the spatial setup for multiple single characteristics into a union, optimal spatial differentiation. Utilizing this method, we are able to propose a spatial structure for a semi-distributed hydrological model, comprising the definition of sub-basins and a zonal classification within each sub-basin. Besides the improved spatial structuring, the performed analysis ameliorates modelling in another way. The spatial variability of catchment characteristics, which is considered by a minimum of heterogeneity in the zones, can be considered in a parameter constrained calibration scheme in a case study both options were used to explore the benefits of incorporating the spatial organisation and derived parameter constraints for the parametrisation of a HBV-96 model. We use two benchmark

  11. Spectral and spatial shaping of a laser-produced ion beam for radiation-biology experiments

    Directory of Open Access Journals (Sweden)

    L. Pommarel

    2017-03-01

    Full Text Available The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system.

  12. 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.

  13. 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...... 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...... 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...

  14. 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.

  15. Mesoscale distribution of Oikopleura and Fritillaria (Appendicularia) in the Southern Gulf of Mexico: spatial segregation

    OpenAIRE

    Flores-Coto, César; Sanvicente-Añorve, Laura; Vázquez-Gutiérrez, Felipe; Sánchez-Ramírez, Marina

    2010-01-01

    The mesoscale spatial distribution of Oikopleura and Fritillaria in the southern Gulf of Mexico was analyzed to know the existence of segregation between them. Samples were taken on 97 stations in the 50 m upper layer. Temperature, salinity and turbidity were measured. The spatial segregation index 'D' was applied to Oikopleura and Fritillaria densities and its significance was tested with Monte Carlo method. Regression Tree (RT) analyses were performed to identify the main environmental fact...

  16. The role of spatial boundaries in shaping long-term event representations

    OpenAIRE

    Horner, Aidan J.; Bisby, James A.; Wang, Aijing; Bogus, Katrina; Burgess, Neil

    2016-01-01

    When remembering the past, we typically recall ?events? that are bounded in time and space. However, as we navigate our environment our senses receive a continuous stream of information. How do we create discrete long-term episodic memories from continuous input? Although previous research has provided evidence for a role of spatial boundaries in the online segmentation of our sensory experience within working memory, it is not known how this segmentation contributes to subsequent long-term e...

  17. THE IMPACT OF SPATIAL AND TEMPORAL RESOLUTIONS IN TROPICAL SUMMER RAINFALL DISTRIBUTION: PRELIMINARY RESULTS

    Directory of Open Access Journals (Sweden)

    Q. Liu

    2017-10-01

    Full Text Available 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.

  18. 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.

  19. Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors

    Directory of Open Access Journals (Sweden)

    Martina Gerken

    2013-06-01

    Full Text Available Multiferroic composite magnetoelectric (ME sensors are based on the elastic coupling of a magnetostrictive phase and a piezoelectric phase. A deformation of the magnetostrictive phase causes strain in the piezoelectric phase and thus an induced voltage. Such sensors may be applied both for static as well as for dynamic magnetic field measurements. Particularly high sensitivities are achieved for operation at a mechanical resonance. Here, the resonance line shape of layered (2-2 composite cantilever ME sensors at the first bending-mode resonance is investigated theoretically. Finite element method (FEM simulations using a linear material model reveal an asymmetric resonance profile and a zero-response frequency for the ME coefficient. Frequency-dependent strain and electric potential distributions inside the magnetoelectric composite are studied for the case of a magnetostrictive-piezoelectric bilayer. It is demonstrated that a positive or a negative voltage may be induced across the piezoelectric layer depending on the position of the neutral plane. The frequency-dependent induced electric potential is investigated for structured cantilevers that exhibit magnetostriction only at specific positions. For static operation an induced voltage is obtained locally at positions with magnetostriction. In addition to this direct effect a resonance-assisted effect is observed for dynamic operation. Magnetostriction in a limited area of the cantilever causes a global vibration of the cantilever. Thus, deformation of the piezoelectric layer and an induced electric potential also occur in areas of the cantilever without magnetostriction. The direct and the resonance-assisted pathway may induce voltages of equal or of opposite sign. The net induced voltage results from the superposition of the two effects. As the resonance-assisted induced voltage changes sign upon passing the resonance frequency, while the direct component is constant, an asymmetric line

  20. Preparation of ring-shaped composite bonded magnets with continuously controlled anisotropy distribution for internal space

    International Nuclear Information System (INIS)

    Yamashita, F; Yamada, O; Ohya, S; Kobayashi, O; Nakano, M; Fukunaga, H

    2010-01-01

    We have already reported an advanced method for producing a radially-anisotropic rare earth composite bonded magnet with continuously controlled direction of anisotropy. The magnet has been applied to an inner rotor as a practical usage. In this study, the outstanding preparation method was adopted into the preparation of a magnet applied for an outer rotor. An optimized condition of extrusion and compaction at an elevated temperature could be obtained. In addition, a low pressure configuration to the ring-shaped magnet from plural preformed magnets was carried out, which had specific distribution of magnetic anisotropy for internal space for a small motor, by using self recoverability based on the viscous deformation without an alignment field. No deterioration of magnetic properties was detected through the process even if those magnets were miniaturized. Resultantly, the (BH) max of a ring-shaped magnet with the continuously controlled direction of magnetic anisotropy attained the value of 186 kJ/m 3 , and we obtained sine-wave magnetic anisotropy distribution, even if those magnets were miniaturized.

  1. 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...... 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...... by growing medium, planting position and competition from other plants. Methods: Five species (Campanula poscharskyana cv. 'Stella', Fragaria vesca cv. 'Småland', Geranium sanguineum cv. 'Max Frei', Sesleria heufleriana and Veronica officinalis cv. 'Allgrün') were grown in three growing media (coir and two...

  2. 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)

  3. ANALYSIS ON THE DYNAMICS OF SPATIAL DISTRIBUTION PATTERN OF MIXED SPIDER POPULATION IN RICE FIELD

    Institute of Scientific and Technical Information of China (English)

    ZhiWang; Zhe-mingYuan; Da-xiangSong; Ming-shengZhu

    2004-01-01

    The results make it clear that there are total 11 families, 29 genera and 43 species of spiders in the rice field of Dong Fang Hong Farm. Among them, there are 8 families, 19 genera and 28 species in the early rice field, and 10 families, 27 genera and 36 species in the late rice field. The spatial distribution pattern of mixed spider populations in rice fields was different during different development stages of rice plant. During the prophase, metaphase and anaphase of early rice plant development, the spatial distribution pattern of mixed spider populations was aggregative, random and aggregative respectively. During the prophase, metaphase and anaphase of late rice plant development, the spatial distribution pattern was uniform, aggregative and uniform respectively.

  4. The change in spatial distribution of upper trapezius muscle activity is correlated to contraction duration.

    Science.gov (United States)

    Farina, Dario; Leclerc, Frédéric; Arendt-Nielsen, Lars; Buttelli, Olivier; Madeleine, Pascal

    2008-02-01

    The aim of the study was to confirm the hypothesis that the longer a contraction is sustained, the larger are the changes in the spatial distribution of muscle activity. For this purpose, surface electromyographic (EMG) signals were recorded with a 13 x 5 grid of electrodes from the upper trapezius muscle of 11 healthy male subjects during static contractions with shoulders 90 degrees abducted until endurance. The entropy (degree of uniformity) and center of gravity of the EMG root mean square map were computed to assess spatial inhomogeneity in muscle activation and changes over time in EMG amplitude spatial distribution. At the endurance time, entropy decreased (mean+/-SD, percent change 2.0+/-1.6%; Pgrid) root mean square was positively correlated with the shift in the center of gravity (R(2)=0.51, P<0.05). Moreover, the shift in the center of gravity was negatively correlated to both initial and final (at the endurance) entropy (R(2)=0.54 and R(2)=0.56, respectively; P<0.01 in both cases), indicating that subjects with less uniform root mean square maps had larger shift of the center of gravity over time. The spatial changes in root mean square EMG were likely due to spatially-dependent changes in motor unit activation during the sustained contraction. It was concluded that the changes in spatial muscle activity distribution play a role in the ability to maintain a static contraction.

  5. Analysis on the Spatial Distribution Characteristics of Maritime traffic profile in Western Taiwan Strait

    International Nuclear Information System (INIS)

    Jinhai, C; Feng, L; Guojun, P

    2014-01-01

    The mathematical statistics and spatial analyses for merchant vessels navigating in Western Taiwan Strait are used to unravel potential spatial heterogeneity based on ship tracking records derived from China's coastal Automatic Identification System shore-based network from October 2011 to September 2012. Two maritime traffic profile's indices, composition of vessels, weighted frequency of ship transits, are proposed. Based on the two indices, the most risky hotspots or areas in the Strait are detected by comparing spatial distribution of maritime traffic volume of fishing boat, container ship, crude oil tanker and all ships exclude fishing boats

  6. Determinants of spatial distribution in a bee community: nesting resources, flower resources, and body size.

    Science.gov (United States)

    Torné-Noguera, Anna; Rodrigo, Anselm; Arnan, Xavier; Osorio, Sergio; Barril-Graells, Helena; da Rocha-Filho, Léo Correia; Bosch, Jordi

    2014-01-01

    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.

  7. 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.

  8. Determinants of Spatial Distribution in a Bee Community: Nesting Resources, Flower Resources, and Body Size

    Science.gov (United States)

    Torné-Noguera, Anna; Rodrigo, Anselm; Arnan, Xavier; Osorio, Sergio; Barril-Graells, Helena; da Rocha-Filho, Léo Correia; Bosch, Jordi

    2014-01-01

    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 (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. PMID:24824445

  9. 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.

  10. 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)

  11. 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.

  12. 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

  13. Evaluating Bayesian spatial methods for modelling species distributions with clumped and restricted occurrence data.

    Science.gov (United States)

    Redding, David W; Lucas, Tim C D; Blackburn, Tim M; Jones, Kate E

    2017-01-01

    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 for spatial

  14. Spatial distribution of fluorescent light emitted from neon and nitrogen excited by low energy electron beams

    International Nuclear Information System (INIS)

    Morozov, A.; Kruecken, R.; Ulrich, A.; Wieser, J.

    2006-01-01

    Side-view intensity profiles of fluorescent light were measured for neon and nitrogen excited with 12 keV electron beams at gas pressures from 250 to 1400 hPa. The intensity profiles were compared with theoretical profiles calculated using the CASINO program which performs Monte Carlo simulations of electron scattering. It was assumed that the spatial distribution of fluorescent intensity is directly proportional to the spatial distribution of energy loss by primary electrons. The comparison shows good correlation of experimental data and the results of numeric simulations

  15. Cross-coherent vector sensor processing for spatially distributed glider networks.

    Science.gov (United States)

    Nichols, Brendan; Sabra, Karim G

    2015-09-01

    Autonomous underwater gliders fitted with vector sensors can be used as a spatially distributed sensor array to passively locate underwater sources. However, to date, the positional accuracy required for robust array processing (especially coherent processing) is not achievable using dead-reckoning while the gliders remain submerged. To obtain such accuracy, the gliders can be temporarily surfaced to allow for global positioning system contact, but the acoustically active sea surface introduces locally additional sensor noise. This letter demonstrates that cross-coherent array processing, which inherently mitigates the effects of local noise, outperforms traditional incoherent processing source localization methods for this spatially distributed vector sensor network.

  16. Probing spatial properties of electronic excitation in water after interaction with temporally shaped femtosecond laser pulses: Experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Thomas; Sarpe, Cristian; Jelzow, Nikolai [Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Lillevang, Lasse H. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Götte, Nadine; Zielinski, Bastian [Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Balling, Peter [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Senftleben, Arne [Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Baumert, Thomas, E-mail: baumert@physik.uni-kassel.de [Institute of Physics and CINSaT, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany)

    2016-06-30

    Highlights: • Temporally asymmetric shaped femtosecond laser pulses lead to excitation over smaller area and larger depth in water. • Transient optical properties are measured radially resolved by spectral interference in an imaging geometry. • Radially resolved spectral interference shows indications of nonlinear propagation effects at high fluences. - Abstract: In this work, laser excitation of water under ambient conditions is investigated by radially resolved common-path spectral interferometry. Water, as a sample system for dielectric materials, is excited by ultrashort bandwidth-limited and temporally asymmetric shaped femtosecond laser pulses, where the latter start with an intense main pulse followed by a decaying pulse sequence, i.e. a temporal Airy pulse. Spectral interference in an imaging geometry allows measurements of the transient optical properties integrated along the propagation through the sample but radially resolved with respect to the transverse beam profile. Since the optical properties reflect the dynamics of the free-electron plasma, such measurements reveal the spatial characteristics of the laser excitation. We conclude that temporally asymmetric shaped laser pulses are a promising tool for high-precision laser material processing, as they reduce the transverse area of excitation, but increase the excitation inside the material along the beam propagation.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Spatial distribution of Plecoptera nymphs in streams of a mountainous area of Central Brazil

    Directory of Open Access Journals (Sweden)

    P. C. BISPO

    Full Text Available In this paper the spatial distribution of Plecoptera nymphs in the Almas' River basin, Pirenópolis, GO, was studied. Two Surber samples, each comprising 20 sampling units and totalling 2 m², were taken in each of the 13 stations, one during the rainy season (January 1994 and the second during the dry season (July 1994. In 5 of these stations, monthly samplings were made from June 1993 to July 1994; in these, temperature, velocity, discharge, electrical conductivity and pH were measured. Regional rainfall was also obtained. To ascertain the distribution of nymphs in the habitat, a separate sample was taken. Of the factors considered, the most important affecting the spatial distribution of the stonefly nymphs were altitude, stream order, and anthropic influence. Locally, the genera Anacroneuria and Kempnyia showed clumped distributions, but the data for Gripopteryx and Tupiperla were inconclusive due to low numbers.

  2. Delineating Hydrofacies Spatial Distribution by Integrating Ensemble Data Assimilation and Indicator Geostatistics

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xuehang [Florida State Univ., Tallahassee, FL (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chen, Xingyuan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ye, Ming [Florida State Univ., Tallahassee, FL (United States); Dai, Zhenxue [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hammond, Glenn Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This study develops a new framework of facies-based data assimilation for characterizing spatial distribution of hydrofacies and estimating their associated hydraulic properties. This framework couples ensemble data assimilation with transition probability-based geostatistical model via a parameterization based on a level set function. The nature of ensemble data assimilation makes the framework efficient and flexible to be integrated with various types of observation data. The transition probability-based geostatistical model keeps the updated hydrofacies distributions under geological constrains. The framework is illustrated by using a two-dimensional synthetic study that estimates hydrofacies spatial distribution and permeability in each hydrofacies from transient head data. Our results show that the proposed framework can characterize hydrofacies distribution and associated permeability with adequate accuracy even with limited direct measurements of hydrofacies. Our study provides a promising starting point for hydrofacies delineation in complex real problems.

  3. The size and spatial distribution of microchannel plate output electron clouds

    International Nuclear Information System (INIS)

    Lapington, J.S.; Edgar, M.L.

    1989-01-01

    An experimental technique for measuring the spatial distribution of the output charge cloud from a microchannel plate (MCP), using a planar, charge-division-type anode is discussed. The anode simultaneously measures, for each charge cloud, both the position of the charge centroid and the fractional charge falling to one side of the split in the pattern. The measurements from several thousand events have been combined to calculate the average spatial distribution of the electron cloud and the dominant factors influencing the charge cloud distribution have been found to be the MCP gain and the MCP-anode accelerating field and geometry. Experimental research on the two dominant factors with respect to ranges of distribution is presented. 10 refs

  4. 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

  5. Input-dependent frequency modulation of cortical gamma oscillations shapes spatial synchronization and enables phase coding.

    Science.gov (United States)

    Lowet, Eric; Roberts, Mark; Hadjipapas, Avgis; Peter, Alina; van der Eerden, Jan; De Weerd, Peter

    2015-02-01

    Fine-scale temporal organization of cortical activity in the gamma range (∼25-80Hz) may play a significant role in information processing, for example by neural grouping ('binding') and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency codes

  6. Spatial distribution of scientific activities: An exploratory analysis of Brazil, 2000–10

    OpenAIRE

    Tulio Chiarini; Vanessa Parreiras Oliveira; Fabio Chaves do Couto e Silva Neto

    2014-01-01

    The literature analyzing the spatial distribution of scientific and technological production in Brazil identifies differences in the regional distribution of scientific and technological resources. In this paper, we contribute to this discussion, by analyzing the dynamics of the production of new scientific knowledge in the states that contributed the most to national scientific production in the period 2000–10: Sao Paulo, Rio de Janeiro, Minas Gerais and Rio Grande do Sul, also known as the ...

  7. 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....

  8. 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...

  9. [Spatial distribution of occupational disease prevalence in Guangzhou and Foshan city by geographic information system].

    Science.gov (United States)

    Tan, Q; Tu, H W; Gu, C H; Li, X D; Li, R Z; Wang, M; Chen, S G; Cheng, Y J; Liu, Y M

    2017-11-20

    Objective: To explore the occupational disease spatial distribution characteristics in Guangzhou and Foshan city in 2006-2013 with Geographic Information System and to provide evidence for making control strategy. Methods: The data on occupational disease diagnosis in Guangzhou and Foshan city from 2006 through 2013 were collected and linked to the digital map at administrative county level with Arc GIS12.0 software for spatial analysis. Results: The maps of occupational disease and Moran's spatial autocor-relation analysis showed that the spatial aggregation existed in Shunde and Nanhai region with Moran's index 1.727, -0.003. Local Moran's I spatial autocorrelation analysis pointed out the "positive high incidence re-gion" and the "negative high incidence region" during 2006~2013. Trend analysis showed that the diagnosis case increased slightly then declined from west to east, increase obviously from north to south, declined from? southwest to northeast, high in the middle and low on both sides in northwest-southeast direction. Conclusions: The occupational disease is obviously geographical distribution in Guangzhou and Foshan city. The corresponding prevention measures should be made according to the geographical distribution.

  10. 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.

  11. 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.

  12. Effect of precipitation spatial distribution uncertainty on the uncertainty bounds of a snowmelt runoff model output

    Science.gov (United States)

    Jacquin, A. P.

    2012-04-01

    This study analyses the effect of precipitation spatial distribution uncertainty on the uncertainty bounds of a snowmelt runoff model's discharge estimates. Prediction uncertainty bounds are derived using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. The model analysed is a conceptual watershed model operating at a monthly time step. The model divides the catchment into five elevation zones, where the fifth zone corresponds to the catchment glaciers. Precipitation amounts at each elevation zone i are estimated as the product between observed precipitation (at a single station within the catchment) and a precipitation factor FPi. Thus, these factors provide a simplified representation of the spatial variation of precipitation, specifically the shape of the functional relationship between precipitation and height. In the absence of information about appropriate values of the precipitation factors FPi, these are estimated through standard calibration procedures. The catchment case study is Aconcagua River at Chacabuquito, located in the Andean region of Central Chile. Monte Carlo samples of the model output are obtained by randomly varying the model parameters within their feasible ranges. In the first experiment, the precipitation factors FPi are considered unknown and thus included in the sampling process. The total number of unknown parameters in this case is 16. In the second experiment, precipitation factors FPi are estimated a priori, by means of a long term water balance between observed discharge at the catchment outlet, evapotranspiration estimates and observed precipitation. In this case, the number of unknown parameters reduces to 11. The feasible ranges assigned to the precipitation factors in the first experiment are slightly wider than the range of fixed precipitation factors used in the second experiment. The mean squared error of the Box-Cox transformed discharge during the calibration period is used for the evaluation of the

  13. 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.

  14. Particle shape accounts for instrumental discrepancy in ice core dust size distributions

    Science.gov (United States)

    Folden Simonsen, Marius; Cremonesi, Llorenç; Baccolo, Giovanni; Bosch, Samuel; Delmonte, Barbara; Erhardt, Tobias; Kjær, Helle Astrid; Potenza, Marco; Svensson, Anders; Vallelonga, Paul

    2018-05-01

    The Klotz Abakus laser sensor and the Coulter counter are both used for measuring the size distribution of insoluble mineral dust particles in ice cores. While the Coulter counter measures particle volume accurately, the equivalent Abakus instrument measurement deviates substantially from the Coulter counter. We show that the difference between the Abakus and the Coulter counter measurements is mainly caused by the irregular shape of dust particles in ice core samples. The irregular shape means that a new calibration routine based on standard spheres is necessary for obtaining fully comparable data. This new calibration routine gives an increased accuracy to Abakus measurements, which may improve future ice core record intercomparisons. We derived an analytical model for extracting the aspect ratio of dust particles from the difference between Abakus and Coulter counter data. For verification, we measured the aspect ratio of the same samples directly using a single-particle extinction and scattering instrument. The results demonstrate that the model is accurate enough to discern between samples of aspect ratio 0.3 and 0.4 using only the comparison of Abakus and Coulter counter data.

  15. 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....

  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. Environmental Justice and the Spatial Distribution of Outdoor Recreation sites: an Applications of Geographic Information Systems

    Science.gov (United States)

    Michael A. Tarrant; H. Ken Cordell

    1999-01-01

    This study examines the spatial distribution of outdoor recreation sites and their proximity to census block groups (CBGs), in order to determine potential socio-economic inequities. It is framed within the context of environmental justice. Information from the Southern Appalachian Assessment database was applied to a case study of the Chattahoochee National Forest in...

  18. AKaplan-Meier estimators of distance distributions for spatial point processes

    NARCIS (Netherlands)

    Baddeley, A.J.; Gill, R.D.

    1997-01-01

    When a spatial point process is observed through a bounded window, edge effects hamper the estimation of characteristics such as the empty space function $F$, the nearest neighbour distance distribution $G$, and the reduced second order moment function $K$. Here we propose and study product-limit

  19. Spatial patterns in the distribution of kimberlites: relationship to tectonic processes and lithosphere structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2015-01-01

    of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal...

  20. Spatial Patterns in Distribution of Kimberlites: Relationship to Tectonic Processes and Lithosphere Structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2014-01-01

    of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal...

  1. 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…

  2. 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

  3. 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)

  4. Spatial dose and microdose distribution in tissues. Ionization, nuclear reactions, multiple scattering simulation of beam transport

    International Nuclear Information System (INIS)

    Jacquot, C.

    1976-01-01

    Computer simulation and nuclear emulsion and gelatin techniques enabled to give the total elastic and inelastic cross sections and to forecast the spatial microdose distributions in cells, nuclei and molecules. For this purpose, the transport of a beam into tissues having a given composition is calculated, the nuclear reactions are generated and the energy depositions in standard planes perpendicular to the beam are recorded

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

    DEFF Research Database (Denmark)

    Lewy, Peter; Kristensen, Kasper

    2009-01-01

    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...

  6. 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.

  7. Spatial structures of the environment and of dispersal impact species distribution in competitive metacommunities.

    Science.gov (United States)

    Ai, Dexiecuo; Gravel, Dominique; Chu, Chengjin; Wang, Gang

    2013-01-01

    The correspondence between species distribution and the environment depends on species' ability to track favorable environmental conditions (via dispersal) and to maintain competitive hierarchy against the constant influx of migrants (mass effect) and demographic stochasticity (ecological drift). Here we report a simulation study of the influence of landscape structure on species distribution. We consider lottery competition for space in a spatially heterogeneous environment, where the landscape is represented as a network of localities connected by dispersal. We quantified the contribution of neutrality and species sorting to their spatial distribution. We found that neutrality increases and the strength of species-sorting decreases with the centrality of a community in the landscape when the average dispersal among communities is low, whereas the opposite was found at elevated dispersal. We also found that the strength of species-sorting increases with environmental heterogeneity. Our results illustrate that spatial structure of the environment and of dispersal must be taken into account for understanding species distribution. We stress the importance of spatial geographic structure on the relative importance of niche vs. neutral processes in controlling community dynamics.

  8. Spatial structures of the environment and of dispersal impact species distribution in competitive metacommunities.

    Directory of Open Access Journals (Sweden)

    Dexiecuo Ai

    Full Text Available The correspondence between species distribution and the environment depends on species' ability to track favorable environmental conditions (via dispersal and to maintain competitive hierarchy against the constant influx of migrants (mass effect and demographic stochasticity (ecological drift. Here we report a simulation study of the influence of landscape structure on species distribution. We consider lottery competition for space in a spatially heterogeneous environment, where the landscape is represented as a network of localities connected by dispersal. We quantified the contribution of neutrality and species sorting to their spatial distribution. We found that neutrality increases and the strength of species-sorting decreases with the centrality of a community in the landscape when the average dispersal among communities is low, whereas the opposite was found at elevated dispersal. We also found that the strength of species-sorting increases with environmental heterogeneity. Our results illustrate that spatial structure of the environment and of dispersal must be taken into account for understanding species distribution. We stress the importance of spatial geographic structure on the relative importance of niche vs. neutral processes in controlling community dynamics.

  9. 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

  10. Spatial regression methods capture prediction uncertainty in species distribution model projections through time

    Science.gov (United States)

    Alan K. Swanson; Solomon Z. Dobrowski; Andrew O. Finley; James H. Thorne; Michael K. Schwartz

    2013-01-01

    The uncertainty associated with species distribution model (SDM) projections is poorly characterized, despite its potential value to decision makers. Error estimates from most modelling techniques have been shown to be biased due to their failure to account for spatial autocorrelation (SAC) of residual error. Generalized linear mixed models (GLMM) have the ability to...

  11. Measurement of spatial dose-rate distribution using a position sensitive detector

    International Nuclear Information System (INIS)

    Emoto, T.; Torii, T.; Nozaki, T.; Ando, H.

    1994-01-01

    Recently, the radiation detectors using plastic scintillation fibers (PSF) have been developed to measure the positions exposed to radiation such as neutrons and high energy charged particles. In particular, the time of flight (TOF) method for measuring the difference of time that two directional signals of scintillation light reach both ends of a PSF is a rather simple method for the measurement of the spatial distribution of fast neutron fluence rate. It is possible to use the PSF in nuclear facility working areas because of its flexibility, small diameter and long length. In order to apply TOF method to measure spatial gamma dose rate distribution, the characteristic tests of a detector using PSFs were carried out. First, the resolution of irradiated positions and the counting efficiency were measured with collimated gamma ray. The sensitivity to unit dose rate was also obtained. The measurement of spatial dose rate distribution was also carried out. The sensor is made of ten bundled PSFs, and the experimental setup is described. The experiment and the results are reported. It was found that the PSF detector has the good performance to measure spatial gamma dose rate distribution. (K.I.)

  12. 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.

  13. Computer simulation of the spatial distribution of optical radiation arising from knocked-out excited particles

    International Nuclear Information System (INIS)

    Gokov, S.P.; Gritsyna, V.V.; Koval', A.G.; Kovtunenko, Yu.I.; Shevchenko, D.I.

    2004-01-01

    The new approach for the explanation of the spatial distribution of the optical radiation arising from knocked-out excited particles is given. Calculated and experimental data for Al (λ=396.1 nm) and Mg (λ=383.8 nm) knocked-out by Ar + (20 keV) beam from MgAl 2 O 4 surface are compared [ru

  14. Modelling the potential spatial distribution of mosquito species using three different techniques

    NARCIS (Netherlands)

    Cianci, D.; Hartemink, N.; Ibáñez-Justicia, A.

    2015-01-01

    Background: Models for the spatial distribution of vector species are important tools in the assessment of the risk of establishment and subsequent spread of vector-borne diseases. The aims of this study are to define the environmental conditions suitable for several mosquito species through species

  15. Biophysical, infrastructural and social heterogeneities explain spatial distribution of waterborne gastrointestinal disease burden in Mexico City

    Science.gov (United States)

    Baeza, Andrés; Estrada-Barón, Alejandra; Serrano-Candela, Fidel; Bojórquez, Luis A.; Eakin, Hallie; Escalante, Ana E.

    2018-06-01

    Due to unplanned growth, large extension and limited resources, most megacities in the developing world are vulnerable to hydrological hazards and infectious diseases caused by waterborne pathogens. Here we aim to elucidate the extent of the relation between the spatial heterogeneity of physical and socio-economic factors associated with hydrological hazards (flooding and scarcity) and the spatial distribution of gastrointestinal disease in Mexico City, a megacity with more than 8 million people. We applied spatial statistics and multivariate regression analyses to high resolution records of gastrointestinal diseases during two time frames (2007–2009 and 2010–2014). Results show a pattern of significant association between water flooding events and disease incidence in the city center (lowlands). We also found that in the periphery (highlands), higher incidence is generally associated with household infrastructure deficiency. Our findings suggest the need for integrated and spatially tailored interventions by public works and public health agencies, aimed to manage socio-hydrological vulnerability in Mexico City.

  16. 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)

  17. Effects of monomer shape on the formation of aggregates from a power law monomer distribution

    International Nuclear Information System (INIS)

    Perry, J; Kimery, J; Matthews, L S; Hyde, T W

    2013-01-01

    The coagulation of dust aggregates is an important process in many physical systems such as the Earth's upper atmosphere, comet tails and protoplanetary discs. Numerical models which study the aggregation in these systems typically involve spherical monomers. There is evidence, however, via the polarization of sunlight in the interstellar medium, as well as optical and LIDAR observations of high-altitude particles in Earth's atmosphere (70–100 km), which indicate that dust monomers may not necessarily be spherical. This study investigates the influence of different ellipsoidal monomer shapes on the morphology of aggregates given various distributions of monomer sizes. Populations of aggregates are grown from a single monomer using a combination of ballistic particle–cluster aggregation and ballistic cluster–cluster aggregation regimes incorporating the rotation of monomers and aggregates. The resulting structures of the aggregates are then compared via the compactness factor, geometric cross-section and friction time. (paper)

  18. 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.

  19. 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

  20. 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

  1. A Comparative Study of Spatially Clustered Distribution of Jumbo Flying Squid (Dosidicus gigas) Offshore Peru

    Institute of Scientific and Technical Information of China (English)

    FENG Yongjiu; CUI Li; CHEN Xinjun; LIU Yu

    2017-01-01

    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 E1 Ni(n)o 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 Ni(n)o,suggesting that such large-scale climate variations could reduce the clustering level ofD.gigas.The catches also showed that warm E1 Ni(n)o 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.

  2. 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.

  3. Spatial Distribution of Zooplankton Diversity across Temporary Pools in a Semiarid Intermittent River

    Directory of Open Access Journals (Sweden)

    Thaís X. Melo

    2013-01-01

    Full Text Available This study describes the richness and density of zooplankton across temporary pools in an intermittent river of semiarid Brazil and evaluates the partitioning of diversity across different spatial scales during the wet and dry periods. Given the highly patchy nature of these pools it is hypothesized that the diversity is not homogeneously distributed across different spatial scales but concentrated at lower levels. The plankton fauna was composed of 37 species. Of these 28 were Rotifera, 5 were Cladocera, and 4 were Copepoda (nauplii of Copepoda were also recorded. We showed that the zooplankton presents a spatially segregated pattern of species composition across river reaches and that at low spatial scales (among pools or different habitats within pools the diversity of species is likely to be affected by temporal changes in physical and chemical characteristics. As a consequence of the drying of pool habitats, the spatial heterogeneity within the study river reaches has the potential to increase β diversity during the dry season by creating patchier assemblages. This spatial segregation in community composition and the patterns of partition of the diversity across the spatial scales leads to a higher total diversity in intermittent streams, compared to less variable environments.

  4. Shape analysis of spatial relationships between orbito-ocular and endocranial structures in modern humans and fossil hominids.

    Science.gov (United States)

    Pereira-Pedro, Ana Sofia; Masters, Michael; Bruner, Emiliano

    2017-12-01

    The orbits and eyes of modern humans are situated directly below the frontal lobes and anterior to the temporal lobes. Contiguity between these orbital and cerebral elements could generate spatial constraints, and potentially lead to deformation of the eye and reduced visual acuity during development. In this shape analysis we evaluate whether and to what extent covariation exists between ocular morphology and the size and spatial position of the frontal and temporal areas in adult modern humans. Magnetic resonance imaging (MRI) was used to investigate patterns of variation among the brain and eyes, while computed tomography (CT) was used to compare cranial morphology in this anatomical region among modern humans, extinct hominids and chimpanzees. Seventeen landmarks and semi-landmarks that capture the outline of the eye, frontal lobe, anterior fossa/orbital roof and the position of the temporal tips were sampled using lateral scout views in two dimensions, after projection of the average grayscale values of each hemisphere, with midsagittal and parasagittal elements overlapped onto the same plane. MRI results demonstrated that eye position in adult humans varies most with regard to its horizontal distance from the temporal lobes and, secondly, in its vertical distance from the frontal lobes. Size was mainly found to covary with the distance between the eye and temporal lobes. Proximity to these cerebral lobes may generate spatial constraints, as some ocular deformation was observed. Considering the CT analysis, modern humans vary most with regard to the orientation of the orbits, while interspecific variation is mainly associated with separation between the orbits and endocranial elements. These findings suggest that size and position of the frontal and temporal lobes can affect eye and orbit morphology, though potential effects on eye shape require further study. In particular, possible effects of these spatial and allometric relationships on the eye and vision

  5. A Bayesian modeling approach for estimation of a shape-free groundwater age distribution using multiple tracers

    NARCIS (Netherlands)

    Massoudieh, A.; Visser, A.; Sharifi, S.; Broers, H.P.

    2014-01-01

    Due to the mixing of groundwaters with different ages in aquifers, groundwater age is more appropriately represented by a distribution rather than a scalar number. To infer a groundwater age distribution from environmental tracers, a mathematical form is often assumed for the shape of the

  6. Spatial distribution of grape root borer (Lepidoptera: Sesiidae) infestations in Virginia vineyards and implications for sampling.

    Science.gov (United States)

    Rijal, J P; Brewster, C C; Bergh, J C

    2014-06-01

    Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae) is a potentially destructive pest of grape vines, Vitis spp. in the eastern United States. After feeding on grape roots for ≍2 yr in Virginia, larvae pupate beneath the soil surface around the vine base. Adults emerge during July and August, leaving empty pupal exuviae on or protruding from the soil. Weekly collections of pupal exuviae from an ≍1-m-diameter weed-free zone around the base of a grid of sample vines in Virginia vineyards were conducted in July and August, 2008-2012, and their distribution was characterized using both nonspatial (dispersion) and spatial techniques. Taylor's power law showed a significant aggregation of pupal exuviae, based on data from 19 vineyard blocks. Combined use of geostatistical and Spatial Analysis by Distance IndicEs methods indicated evidence of an aggregated pupal exuviae distribution pattern in seven of the nine blocks used for those analyses. Grape root borer pupal exuviae exhibited spatial dependency within a mean distance of 8.8 m, based on the range values of best-fitted variograms. Interpolated and clustering index-based infestation distribution maps were developed to show the spatial pattern of the insect within the vineyard blocks. The temporal distribution of pupal exuviae showed that the majority of moths emerged during the 3-wk period spanning the third week of July and the first week of August. The spatial distribution of grape root borer pupal exuviae was used in combination with temporal moth emergence patterns to develop a quantitative and efficient sampling scheme to assess infestations.

  7. 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.

  8. 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

  9. [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.

  10. A spatial scan statistic for survival data based on Weibull distribution.

    Science.gov (United States)

    Bhatt, Vijaya; Tiwari, Neeraj

    2014-05-20

    The spatial scan statistic has been developed as a geographical cluster detection analysis tool for different types of data sets such as Bernoulli, Poisson, ordinal, normal and exponential. We propose a scan statistic for survival data based on Weibull distribution. It may also be used for other survival distributions, such as exponential, gamma, and log normal. The proposed method is applied on the survival data of tuberculosis patients for the years 2004-2005 in Nainital district of Uttarakhand, India. Simulation studies reveal that the proposed method performs well for different survival distribution functions. Copyright © 2013 John Wiley & Sons, Ltd.

  11. 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.

  12. 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.

  13. Seasonal and spatial distribution of metals in surface sediment of an urban estuary

    International Nuclear Information System (INIS)

    Buggy, Conor J.; Tobin, John M.

    2008-01-01

    Aquatic pollution by metals is of concern because of various toxic effects to marine life. The Tolka Estuary, Co. Dublin, Ireland, is a typical Irish urban estuary. It has a significant metal loading originating from the urban environment. Results of a 25 month analysis of cadmium, copper, lead and zinc spatial and temporal distribution over 10 sample locations in this estuary are presented in this paper. Metal concentrations were analysed using differential pulse polarography. Significant seasonal and spatial trends in metal distribution were observed over the 25 months. Sediment metal concentrations gradually increased (30-120%) in spring to a maximum at the end of summer which was followed by a decrease in winter months (30-60%). Sediment organic matter (OM) concentrations exhibited similar seasonal trends and a positive correlation between OM and metal distributions was observed, implying OM had an influence on metal distributions over time. - Assessment and correlation of the seasonal and spatial distribution of metals and organic matter in surface sediment of an urban estuary

  14. Spatial distribution of ozone over Indonesia (Study case: Forest fire event 2015)

    Science.gov (United States)

    Muslimah, Sri; Buce Saleh, Muhamad; Hidayat, Rahmat

    2018-05-01

    Tropospheric ozone is known as surface ozone and caused several health impact. The objective of this study was to analysis spatial distribution of tropospheric ozone over Indonesia case study forest fire event in 2015. Monthly observation measured by Ozone Monitoring Instrument (OMI) have been analysed from January – December 2015 to study spatial distribution of tropospheric ozone related to forest fire event 2015. The study discovered high level of tropospheric column ozone (TCO) from October to November 2015. The result shows increasing average of TCO from September to October almost 6 DU. Meanwhile, monthly number of hotspot is higher in September 2015 with total number 257 hotspot which is acquired by Moderate Resolution Imaging Spectrometer (MODIS) Terra version 6.1 with confidence level same or more than 90%. The hotspot distribution compared with spatial TCO distribution and shows interesting time lag with respect to hotspot distribution, one month. Further study for daily comparison of TCO and forest fire event needed. This result suggested that the tropospheric ozone over the Indonesian region increases in 2015 were remarkable and corresponded to forest fire event.

  15. 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)

  16. STRUCTURE, SPATIAL DISTRIBUTION AND SEED YIELD FOR ANDIROBA (Carapa guianensis Aubl. IN SOUTH RORAIMA

    Directory of Open Access Journals (Sweden)

    Helio Tonini

    2009-10-01

    Full Text Available Andiroba is one of the Amazon species with great potential of exploration for timber and non-timber forest products (NFTPs. This work was carried out with the objective of studying the population structure, spatial distribution and seed yield in a native forest of andiroba in the south of Roraima state. A permanent sample plot of 300 x 300 m (9 ha was installed and all the trees with DBH equal or superior to 10 cm were identified, mapped and measured. In each tree, the light climate, crown form and lianas load were appraised. To identify the spatial distribution, the medium variance/average rate and the Morisita’s Index were used. The seed yield data were obtained by the seed weighing, being 145 trees monitored during 2006. The population presented a diametric distribution of the j inverted type, and a seed yield of 65,4 kg.ha-1 with average of 8,3 kg.tree-1 was observed. DBH ≥ 30 cm was considered as borderline for commercial seed yield, allowing stratifying the population in juveniles (DBH ≤ 30 cm and adults (DBH > 30 cm. The spatial distribution analysis showed that adult individuals presented random distribution and the juveniles tendency of grouping.

  17. Historical biome distribution and recent human disturbance shape the diversity of arbuscular mycorrhizal fungi.

    Science.gov (United States)

    Pärtel, Meelis; Öpik, Maarja; Moora, Mari; Tedersoo, Leho; Szava-Kovats, Robert; Rosendahl, Søren; Rillig, Matthias C; Lekberg, Ylva; Kreft, Holger; Helgason, Thorunn; Eriksson, Ove; Davison, John; de Bello, Francesco; Caruso, Tancredi; Zobel, Martin

    2017-10-01

    The availability of global microbial diversity data, collected using standardized metabarcoding techniques, makes microorganisms promising models for investigating the role of regional and local factors in driving biodiversity. Here we modelled the global diversity of symbiotic arbuscular mycorrhizal (AM) fungi using currently available data on AM fungal molecular diversity (small subunit (SSU) ribosomal RNA (rRNA) gene sequences) in field samples. To differentiate between regional and local effects, we estimated species pools (sets of potentially suitable taxa) for each site, which are expected to reflect regional processes. We then calculated community completeness, an index showing the fraction of the species pool present, which is expected to reflect local processes. We found significant spatial variation, globally in species pool size, as well as in local and dark diversity (absent members of the species pool). Species pool size was larger close to areas containing tropical grasslands during the last glacial maximum, which are possible centres of diversification. Community completeness was greater in regions of high wilderness (remoteness from human disturbance). Local diversity was correlated with wilderness and current connectivity to mountain grasslands. Applying the species pool concept to symbiotic fungi facilitated a better understanding of how biodiversity can be jointly shaped by large-scale historical processes and recent human disturbance. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  18. 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.

  19. Spatial distribution and longitudinal development of deep cortical sulcal landmarks in infants.

    Science.gov (United States)

    Meng, Yu; Li, Gang; Lin, Weili; Gilmore, John H; Shen, Dinggang

    2014-10-15

    Sulcal pits, the locally deepest points in sulci of the highly convoluted and variable cerebral cortex, are found to be spatially consistent across human adult individuals. It is suggested that sulcal pits are genetically controlled and have close relationships with functional areas. To date, the existing imaging studies of sulcal pits are mainly focused on adult brains, yet little is known about the spatial distribution and temporal development of sulcal pits in the first 2 years of life, which is the most dynamic and critical period of postnatal brain development. Studying sulcal pits during this period would greatly enrich our limited understandings of the origins and developmental trajectories of sulcal pits, and would also provide important insights into many neurodevelopmental disorders associated with abnormal cortical foldings. In this paper, by using surface-based morphometry, for the first time, we systemically investigated the spatial distribution and temporal development of sulcal pits in major cortical sulci from 73 healthy infants, each with three longitudinal 3T MR scans at term birth, 1 year, and 2 years of age. Our results suggest that the spatially consistent distributions of sulcal pits in major sulci across individuals have already existed at term birth and this spatial distribution pattern keeps relatively stable in the first 2 years of life, despite that the cerebral cortex expands dramatically and the sulcal depth increases considerably during this period. Specially, the depth of sulcal pits increases regionally heterogeneously, with more rapid growth in the high-order association cortex, including the prefrontal and temporal cortices, than the sensorimotor cortex in the first 2 years of life. Meanwhile, our results also suggest that there exist hemispheric asymmetries of the spatial distributions of sulcal pits in several cortical regions, such as the central, superior temporal and postcentral sulci, consistently from birth to 2 years of age

  20. Within-field spatial distribution of Megacopta cribraria (Hemiptera: Plataspidae) in soybean (Fabales: Fabaceae).

    Science.gov (United States)

    Seiter, Nicholas J; Reay-Jones, Francis P F; Greene, Jeremy K

    2013-12-01

    The recently introduced plataspid Megacopta cribraria (F.) can infest fields of soybean (Glycine max (L.) Merrill) in the southeastern United States. Grid sampling in four soybean fields was conducted in 2011 and 2012 to study the spatial distribution of M. cribraria adults, nymphs, and egg masses. Peak oviposition typically occurred in early August, while peak levels of adults occurred in mid-late September. The overall sex ratio was slightly biased at 53.1 ± 0.2% (SEM) male. Sweep samples of nymphs were biased toward late instars. All three life stages exhibited a generally aggregated spatial distribution based on Taylor's power law, Iwao's patchiness regression, and spatial analysis by distance indices (SADIE). Interpolation maps of local SADIE aggregation indices showed clusters of adults and nymphs located at field edges, and mean densities of adults were higher in samples taken from field edges than in those taken from field interiors. Adults and nymphs were often spatially associated based on SADIE, indicating spatial stability across life stages.

  1. Transoceanic Dispersal and Plate Tectonics Shaped Global Cockroach Distributions: Evidence from Mitochondrial Phylogenomics.

    Science.gov (United States)

    Bourguignon, Thomas; Tang, Qian; Ho, Simon Y W; Juna, Frantisek; Wang, Zongqing; Arab, Daej A; Cameron, Stephen L; Walker, James; Rentz, David; Evans, Theodore A; Lo, Nathan

    2017-04-01

    Following the acceptance of plate tectonics theory in the latter half of the 20th century, vicariance became the dominant explanation for the distributions of many plant and animal groups. In recent years, however, molecular-clock analyses have challenged a number of well-accepted hypotheses of vicariance. As a widespread group of insects with a fossil record dating back 300 My, cockroaches provide an ideal model for testing hypotheses of vicariance through plate tectonics versus transoceanic dispersal. However, their evolutionary history remains poorly understood, in part due to unresolved relationships among the nine recognized families. Here, we present a phylogenetic estimate of all extant cockroach families, as well as a timescale for their evolution, based on the complete mitochondrial genomes of 119 cockroach species. Divergence dating analyses indicated that the last common ancestor of all extant cockroaches appeared ∼235 Ma, ∼95 My prior to the appearance of fossils that can be assigned to extant families, and before the breakup of Pangaea began. We reconstructed the geographic ranges of ancestral cockroaches and found tentative support for vicariance through plate tectonics within and between several major lineages. We also found evidence of transoceanic dispersal in lineages found across the Australian, Indo-Malayan, African, and Madagascan regions. Our analyses provide evidence that both vicariance and dispersal have played important roles in shaping the distribution and diversity of these insects.

  2. Floral abundance, richness, and spatial distribution drive urban garden bee communities.

    Science.gov (United States)

    Plascencia, M; Philpott, S M

    2017-10-01

    In urban landscapes, gardens provide refuges for bee diversity, but conservation potential may depend on local and landscape features. Foraging and population persistence of bee species, as well as overall pollinator community structure, may be supported by the abundance, richness, and spatial distribution of floral resources. Floral resources strongly differ in urban gardens. Using hand netting and pan traps to survey bees, we examined whether abundance, richness, and spatial distribution of floral resources, as well as ground cover and garden landscape surroundings influence bee abundance, species richness, and diversity on the central coast of California. Differences in floral abundance and spatial distribution, as well as urban cover in the landscape, predicted different bee community variables. Abundance of all bees and of honeybees (Apis mellifera) was lower in sites with more urban land cover surrounding the gardens. Honeybee abundance was higher in sites with patchy floral resources, whereas bee species richness and bee diversity was higher in sites with more clustered floral resources. Surprisingly, bee species richness and bee diversity was lower in sites with very high floral abundance, possibly due to interactions with honeybees. Other studies have documented the importance of floral abundance and landscape surroundings for bees in urban gardens, but this study is the first to document that the spatial arrangement of flowers strongly predicts bee abundance and richness. Based on these findings, it is likely that garden managers may promote bee conservation by managing for floral connectivity and abundance within these ubiquitous urban habitats.

  3. 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.

  4. 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.

  5. 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.

  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. 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.

  8. 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

  9. Spatial Distribution Characteristics of Healthcare Facilities in Nanjing: Network Point Pattern Analysis and Correlation Analysis

    Directory of Open Access Journals (Sweden)

    Jianhua Ni

    2016-08-01

    Full Text Available The spatial distribution of urban service facilities is largely constrained by the road network. In this study, network point pattern analysis and correlation analysis were used to analyze the relationship between road network and healthcare facility distribution. The weighted network kernel density estimation method proposed in this study identifies significant differences between the outside and inside areas of the Ming city wall. The results of network K-function analysis show that private hospitals are more evenly distributed than public hospitals, and pharmacy stores tend to cluster around hospitals along the road network. After computing the correlation analysis between different categorized hospitals and street centrality, we find that the distribution of these hospitals correlates highly with the street centralities, and that the correlations are higher with private and small hospitals than with public and large hospitals. The comprehensive analysis results could help examine the reasonability of existing urban healthcare facility distribution and optimize the location of new healthcare facilities.

  10. 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.

  11. From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly.

    Science.gov (United States)

    Rossetto, Maurizio; Kooyman, Robert; Yap, Jia-Yee S; Laffan, Shawn W

    2015-12-07

    Seed dispersal is a key process in plant spatial dynamics. However, consistently applicable generalizations about dispersal across scales are mostly absent because of the constraints on measuring propagule dispersal distances for many species. Here, we focus on fleshy-fruited taxa, specifically taxa with large fleshy fruits and their dispersers across an entire continental rainforest biome. We compare species-level results of whole-chloroplast DNA analyses in sister taxa with large and small fruits, to regional plot-based samples (310 plots), and whole-continent patterns for the distribution of woody species with either large (more than 30 mm) or smaller fleshy fruits (1093 taxa). The pairwise genomic comparison found higher genetic distances between populations and between regions in the large-fruited species (Endiandra globosa), but higher overall diversity within the small-fruited species (Endiandra discolor). Floristic comparisons among plots confirmed lower numbers of large-fruited species in areas where more extreme rainforest contraction occurred, and re-colonization by small-fruited species readily dispersed by the available fauna. Species' distribution patterns showed that larger-fruited species had smaller geographical ranges than smaller-fruited species and locations with stable refugia (and high endemism) aligned with concentrations of large fleshy-fruited taxa, making them a potentially valuable conservation-planning indicator. © 2015 The Author(s).

  12. Incorporating Human Movement Behavior into the Analysis of Spatially Distributed Infrastructure.

    Directory of Open Access Journals (Sweden)

    Lihua Wu

    Full Text Available For the first time in human history, the majority of the world's population resides in urban areas. Therefore, city managers are faced with new challenges related to the efficiency, equity and quality of the supply of resources, such as water, food and energy. Infrastructure in a city can be viewed as service points providing resources. These service points function together as a spatially collaborative system to serve an increasing population. To study the spatial collaboration among service points, we propose a shared network according to human's collective movement and resource usage based on data usage detail records (UDRs from the cellular network in a city in western China. This network is shown to be not scale-free, but exhibits an interesting triangular property governed by two types of nodes with very different link patterns. Surprisingly, this feature is consistent with the urban-rural dualistic context of the city. Another feature of the shared network is that it consists of several spatially separated communities that characterize local people's active zones but do not completely overlap with administrative areas. According to these features, we propose the incorporation of human movement into infrastructure classification. The presence of well-defined spatially separated clusters confirms the effectiveness of this approach. In this paper, our findings reveal the spatial structure inside a city, and the proposed approach provides a new perspective on integrating human movement into the study of a spatially distributed system.

  13. Incorporating Human Movement Behavior into the Analysis of Spatially Distributed Infrastructure.

    Science.gov (United States)

    Wu, Lihua; Leung, Henry; Jiang, Hao; Zheng, Hong; Ma, Li

    2016-01-01

    For the first time in human history, the majority of the world's population resides in urban areas. Therefore, city managers are faced with new challenges related to the efficiency, equity and quality of the supply of resources, such as water, food and energy. Infrastructure in a city can be viewed as service points providing resources. These service points function together as a spatially collaborative system to serve an increasing population. To study the spatial collaboration among service points, we propose a shared network according to human's collective movement and resource usage based on data usage detail records (UDRs) from the cellular network in a city in western China. This network is shown to be not scale-free, but exhibits an interesting triangular property governed by two types of nodes with very different link patterns. Surprisingly, this feature is consistent with the urban-rural dualistic context of the city. Another feature of the shared network is that it consists of several spatially separated communities that characterize local people's active zones but do not completely overlap with administrative areas. According to these features, we propose the incorporation of human movement into infrastructure classification. The presence of well-defined spatially separated clusters confirms the effectiveness of this approach. In this paper, our findings reveal the spatial structure inside a city, and the proposed approach provides a new perspective on integrating human movement into the study of a spatially distributed system.

  14. 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

  15. Effects of Shape and Strain Distribution of Quantum Dots on Optical Transition in the Quantum Dot Infrared Photodetectors

    Directory of Open Access Journals (Sweden)

    Fu Y

    2008-01-01

    Full Text Available Abstract We present a systemic theoretical study of the electronic properties of the quantum dots inserted in quantum dot infrared photodetectors (QDIPs. The strain distribution of three different shaped quantum dots (QDs with a same ratio of the base to the vertical aspect is calculated by using the short-range valence-force-field (VFF approach. The calculated results show that the hydrostatic strain ɛHvaries little with change of the shape, while the biaxial strain ɛBchanges a lot for different shapes of QDs. The recursion method is used to calculate the energy levels of the bound states in QDs. Compared with the strain, the shape plays a key role in the difference of electronic bound energy levels. The numerical results show that the deference of bound energy levels of lenslike InAs QD matches well with the experimental results. Moreover, the pyramid-shaped QD has the greatest difference from the measured experimental data.

  16. 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.

  17. 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.

  18. Estimating the spatial distribution of artificial groundwater recharge using multiple tracers.

    Science.gov (United States)

    Moeck, Christian; Radny, Dirk; Auckenthaler, Adrian; Berg, Michael; Hollender, Juliane; Schirmer, Mario

    2017-10-01

    Stable isotopes of water, organic micropollutants and hydrochemistry data are powerful tools for identifying different water types in areas where knowledge of the spatial distribution of different groundwater is critical for water resource management. An important question is how the assessments change if only one or a subset of these tracers is used. In this study, we estimate spatial artificial infiltration along an infiltration system with stage-discharge relationships and classify different water types based on the mentioned hydrochemistry data for a drinking water production area in Switzerland. Managed aquifer recharge via surface water that feeds into the aquifer creates a hydraulic barrier between contaminated groundwater and drinking water wells. We systematically compare the information from the aforementioned tracers and illustrate differences in distribution and mixing ratios. Despite uncertainties in the mixing ratios, we found that the overall spatial distribution of artificial infiltration is very similar for all the tracers. The highest infiltration occurred in the eastern part of the infiltration system, whereas infiltration in the western part was the lowest. More balanced infiltration within the infiltration system could cause the elevated groundwater mound to be distributed more evenly, preventing the natural inflow of contaminated groundwater. Dedicated to Professor Peter Fritz on the occasion of his 80th birthday.

  19. 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)

  20. 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

  1. Fat Mass Follows a U-Shaped Distribution Based on Estradiol Levels in Postmenopausal Women

    Directory of Open Access Journals (Sweden)

    Georgia Colleluori

    2018-07-01

    Full Text Available ObjectiveEstradiol (E2 regulates adipose tissue resulting in increased fat mass (FM with declining E2. However, increased visceral fat and hyperestrogenemia are features of obese individuals. It is possible that adipocytes in obese individuals are less sensitive to E2 resulting in higher FM. Our objective is to identify the range of serum E2 for which postmenopausal women have the lowest FM and best body composition.MethodsCross-sectional data from 252 community-dwelling postmenopausal women, 42–90 years old. Subjects were stratified into categories of E2 (pg/ml: (1 ≤10.5; (2 10.6–13.9; (3 14.0–17.4; and (4 ≥17.5. Body composition by dual-energy X-ray absorptiometry. Serum E2 by radioimmunoassay. Between-group comparisons by analysis of covariance.ResultsE2 linearly increased with increasing body weight and body mass index (r = 0.15 and p = 0.01 for both, but not with total FM (kg or % FM (r = 0.07, p = 0.34 and r = −0.04, p = 0.56, respectively. However, total FM (kg followed a U-shaped distribution and was significantly lower in group 3 (27.6 ± 10.6, compared with groups 1: (34.6 ± 12.5, 2: (34.0 ± 12.4, and 4: (37.0 ± 10.6, p = 0.005. % FM was also lowest in group 3. While fat-free mass (FFM, kg increased with increasing E2 (p < 0.001, % FFM was highest in group 3.ConclusionIn our population of postmenopausal women, FM followed a U-shaped distribution according to E2 levels. E2 between 14.0 and 17.4 pg/ml is associated with the best body composition, i.e., lowest total and % FM and highest % FFM. Given the role of E2 in regulating body fat, high FM at the high end of the E2 spectrum may suggest reduced E2 sensitivity in adipocytes among obese postmenopausal women.Clinical TrialsClinicalTrials.gov identifier: NCT00146107.

  2. Predicting the spatial distribution of Lonicera japonica, based on species occurrence data from two watersheds in Western Kentucky and Tennessee

    Science.gov (United States)

    Dongjiao Liu; Hao Jiang; Robin Zhang; Kate S. He

    2011-01-01

    The spatial distribution of most invasive plants is poorly documented and studied. This project examined and compared the spatial distribution of a successful invasive plant, Japanese honeysuckle (Lonicera japonica), in two similar-sized but ecologically distinct watersheds in western Kentucky (Ledbetter Creek) and western Tennessee (Panther Creek)....

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Spatial distribution of carbon species in laser ablation of graphite target

    International Nuclear Information System (INIS)

    Ikegami, T.; Ishibashi, S.; Yamagata, Y.; Ebihara, K.; Thareja, R.K.; Narayan, J.

    2001-01-01

    We report on the temporal evolution and spatial distribution of C 2 and C 3 molecules produced by KrF laser ablation of a graphite target using laser induced fluorescence imaging and optical emission spectroscopy. Spatial density profiles of C 2 were measured using two-dimensional fluorescence in various pressures of different ambient (vacuum, nitrogen, oxygen, hydrogen, helium, and argon) gases at various ablation laser fluences and ablation area. A large yield of C 2 is observed in the central part of the plume and near the target surface and its density and distribution was affected by the laser fluence and ambient gas. Fluorescent C 3 was studied in Ar gas and the yield of C 3 is enhanced at higher gas pressure and longer delay times after ablation

  8. Spatial Distribution of Transgenic Protein After Gene Electrotransfer to Porcine Muscle

    DEFF Research Database (Denmark)

    Spanggaard, Iben; Corydon, Thomas; 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...... electrotransfer to muscle in a large animal model has not yet been investigated. In this study, 17 different doses of plasmid DNA (1-1500 μg firefly luciferase pCMV-Luc) were delivered in vivo to porcine gluteal muscle using electroporation. Forty-eight hours post treatment several biopsies were obtained from...... 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...

  9. Physical Property Control on the Cellular Uptake Pathway and Spatial Distribution of Nanoparticles in Cells.

    Science.gov (United States)

    Ahn, Sungsook; Seo, Eunseok; Kim, Ki Hean; Lee, Sang Joon

    2015-06-01

    Nanoparticles have been developed in broad biomedical research in terms of effective cellular interactions to treat and visualize diseased cells. Considering the charge and polar functional groups of proteins that are embedded in cellular membranes, charged nanoparticles have been strategically developed to enhance electrostatic cellular interactions. In this study, we show that cellular uptake efficiency, pathway, and spatial distribution of gold nanoparticles in a cell are significantly modulated based on the surface condition of gold nanoparticles and human cancer cells that were tuned by controlling the pH of the medium and by introducing an electron beam. Cellular uptake efficiency is increased when electrostatic attraction is induced between the cells and the gold nanoparticles. Cell surface modification changes the cellular uptake pathways of the gold nanoparticles and concentrates the gold nanoparticles at the membrane region. Surface modification of the gold nanoparticles also contributes to deep penetration and homogeneous spatial distributions in a cell.

  10. Non-monotonic spatial distribution of the interstellar dust in astrospheres: finite gyroradius effect

    Science.gov (United States)

    Katushkina, O. A.; Alexashov, D. B.; Izmodenov, V. V.; Gvaramadze, V. V.

    2017-02-01

    High-resolution mid-infrared observations of astrospheres show that many of them have filamentary (cirrus-like) structure. Using numerical models of dust dynamics in astrospheres, we suggest that their filamentary structure might be related to specific spatial distribution of the interstellar dust around the stars, caused by a gyrorotation of charged dust grains in the interstellar magnetic field. Our numerical model describes the dust dynamics in astrospheres under an influence of the Lorentz force and assumption of a constant dust charge. Calculations are performed for the dust grains with different sizes separately. It is shown that non-monotonic spatial dust distribution (viewed as filaments) appears for dust grains with the period of gyromotion comparable with the characteristic time-scale of the dust motion in the astrosphere. Numerical modelling demonstrates that the number of filaments depends on charge-to-mass ratio of dust.

  11. Reduction of spatial distribution of risk factors for transportation of contaminants released by coal mining activities.

    Science.gov (United States)

    Karan, Shivesh Kishore; Samadder, Sukha Ranjan

    2016-09-15

    It is reported that water-energy nexus composes two of the biggest development and human health challenges. In the present study we presented a Risk Potential Index (RPI) model which encapsulates Source, Vector (Transport), and Target risks for forecasting surface water contamination. The main aim of the model is to identify critical surface water risk zones for an open cast mining environment, taking Jharia Coalfield, India as the study area. The model also helps in feasible sampling design. Based on spatial analysis various risk zones were successfully delineated. Monthly RPI distribution revealed that the risk of surface water contamination was highest during the monsoon months. Surface water samples were analysed to validate the model. A GIS based alternative management option was proposed to reduce surface water contamination risk and observed 96% and 86% decrease in the spatial distribution of very high risk areas for the months June and July respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. 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)

  13. The spatial distribution of leprosy cases during 15 years of a leprosy control program in Bangladesh: An obsersvational study

    NARCIS (Netherlands)

    Fischer, E.A.J.; pahan, D.; Chowdhury, S.K.; Richardus, J.H.

    2008-01-01

    Background - An uneven spatial distribution of leprosy can be caused by the influence of geography on the distribution of risk factors over the area, or by population characteristics that are heterogeneously distributed over the area. We studied the distribution of leprosy cases detected by a

  14. Spatial distribution of cutaneous leishmaniasis in the state of Paraná, Brazil.

    Science.gov (United States)

    Melo, Helen Aline; Rossoni, Diogo Francisco; Teodoro, Ueslei

    2017-01-01

    The geographic distribution of cutaneous leishmaniasis (CL) makes it a disease of major clinical importance in Brazil, where it is endemic in the state of Paraná. The objective of this study was to analyze the spatial distribution of CL in Paraná between 2001 and 2015, based on data from the Sistema de Informação de Agravos de Notificação (Information System for Notifiable Diseases) regarding autochthonous CL cases. Spatial autocorrelation was performed using Moran's Global Index and the Local Indicator of Spatial Association (LISA). The construction of maps was based on categories of association (high-high, low-low, high-low, and low-high). A total of 4,557 autochthonous cases of CL were registered in the state of Paraná, with an annual average of 303.8 (± 135.2) and a detection coefficient of 2.91. No correlation was found between global indices and their respective significance in 2001 (I = -0.456, p = 0.676), but evidence of spatial autocorrelation was found in other years (pCinzas-Laranjinha, and Ribeira areas. The state of Paraná should keep a constant surveillance over CL due to the prominent presence of socioeconomic and environmental factors such as the favorable circumstances for the vectors present in peri-urban and agriculture áreas.

  15. Spatial Distribution of the Coefficient of Variation for the Paleo-Earthquakes in Japan

    Science.gov (United States)

    Nomura, S.; Ogata, Y.

    2015-12-01

    Renewal processes, point prccesses in which intervals between consecutive events are independently and identically distributed, are frequently used to describe this repeating earthquake mechanism and forecast the next earthquakes. However, one of the difficulties in applying recurrent earthquake models is the scarcity of the historical data. Most studied fault segments have few, or only one observed earthquake that often have poorly constrained historic and/or radiocarbon ages. The maximum likelihood estimate from such a small data set can have a large bias and error, which tends to yield high probability for the next event in a very short time span when the recurrence intervals have similar lengths. On the other hand, recurrence intervals at a fault depend on the long-term slip rate caused by the tectonic motion in average. In addition, recurrence times are also fluctuated by nearby earthquakes or fault activities which encourage or discourage surrounding seismicity. These factors have spatial trends due to the heterogeneity of tectonic motion and seismicity. Thus, this paper introduces a spatial structure on the key parameters of renewal processes for recurrent earthquakes and estimates it by using spatial statistics. Spatial variation of mean and variance parameters of recurrence times are estimated in Bayesian framework and the next earthquakes are forecasted by Bayesian predictive distributions. The proposal model is applied for recurrent earthquake catalog in Japan and its result is compared with the current forecast adopted by the Earthquake Research Committee of Japan.

  16. Spatial structure and distribution of small pelagic fish in the northwestern Mediterranean Sea.

    Science.gov (United States)

    Saraux, Claire; Fromentin, Jean-Marc; Bigot, Jean-Louis; Bourdeix, Jean-Hervé; Morfin, Marie; Roos, David; Van Beveren, Elisabeth; Bez, Nicolas

    2014-01-01

    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.

  17. 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.

  18. 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...

  19. Spatial distribution of the gamma-ray bursts at very high redshift

    Science.gov (United States)

    Mészáros, Attila

    2018-05-01

    The author - with his collaborators - already in years 1995-96 have shown - purely from the analyses of the observations - that the gamma-ray bursts (GRBs) can be till redshift 20. Since that time several other statistical studies of the spatial distribution of GRBs were provided. Remarkable conclusions concerning the star-formation rate and the validity of the cosmological principle were obtained about the regions of the cosmic dawn. In this contribution these efforts are surveyed.

  20. 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.

  1. 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.

  2. 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.

  3. Incorporating spatial autocorrelation into species distribution models alters forecasts of climate-mediated range shifts.

    Science.gov (United States)

    Crase, Beth; Liedloff, Adam; Vesk, Peter A; Fukuda, Yusuke; Wintle, Brendan A

    2014-08-01

    Species distribution models (SDMs) are widely used to forecast changes in the spatial distributions of species and communities in response to climate change. However, spatial autocorrelation (SA) is rarely accounted for in these models, despite its ubiquity in broad-scale ecological data. While spatial autocorrelation in model residuals is known to result in biased parameter estimates and the inflation of type I errors, the influence of unmodeled SA on species' range forecasts is poorly understood. Here we quantify how accounting for SA in SDMs influences the magnitude of range shift forecasts produced by SDMs for multiple climate change scenarios. SDMs were fitted to simulated data with a known autocorrelation structure, and to field observations of three mangrove communities from northern Australia displaying strong spatial autocorrelation. Three modeling approaches were implemented: environment-only models (most frequently applied in species' range forecasts), and two approaches that incorporate SA; autologistic models and residuals autocovariate (RAC) models. Differences in forecasts among modeling approaches and climate scenarios were quantified. While all model predictions at the current time closely matched that of the actual current distribution of the mangrove communities, under the climate change scenarios environment-only models forecast substantially greater range shifts than models incorporating SA. Furthermore, the magnitude of these differences intensified with increasing increments of climate change across the scenarios. When models do not account for SA, forecasts of species' range shifts indicate more extreme impacts of climate change, compared to models that explicitly account for SA. Therefore, where biological or population processes induce substantial autocorrelation in the distribution of organisms, and this is not modeled, model predictions will be inaccurate. These results have global importance for conservation efforts as inaccurate

  4. 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.

  5. 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.

  6. 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

  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. 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.

  9. Spatial distribution of vehicle emission inventories in the Federal District, Brazil

    Science.gov (United States)

    Réquia, Weeberb João; Koutrakis, Petros; Roig, Henrique Llacer

    2015-07-01

    Air pollution poses an important public health risk, especially in large urban areas. Information about the spatial distribution of air pollutants can be used as a tool for developing public policies to reduce source emissions. Air pollution monitoring networks provide information about pollutant concentrations; however, they are not available in every urban area. Among the 5570 cities in Brazil, for example, only 1.7% of them have air pollution monitoring networks. In this study we assess vehicle emissions for main traffic routes of the Federal District (state of Brazil) and characterize their spatial patterns. Toward this end, we used a bottom-up method to predict emissions and to characterize their spatial patterns using Global Moran's (Spatial autocorrelation analysis) and Getis-Ord General G (High/Low cluster analysis). Our findings suggested that light duty vehicles are primarily responsible for the vehicular emissions of CO (68.9%), CH4 (93.6%), and CO2 (57.9%), whereas heavy duty vehicles are primarily responsible for the vehicular emissions of NMHC (92.9%), NOx (90.7%), and PM (97.4%). Furthermore, CO2 is the pollutant with the highest emissions, over 30 million tons/year. In the spatial autocorrelation analysis was identified cluster (p < 0.01) for all types of vehicles and for all pollutants. However, we identified high cluster only for the light vehicles.

  10. Measurement of spatial dose distribution for evaluation operator dose during nero-interventional procedures

    International Nuclear Information System (INIS)

    Han, Su Chul; Hong, Dong Hee

    2016-01-01

    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

  11. Spatial distribution and optimal harvesting of an age-structured population in a fluctuating environment.

    Science.gov (United States)

    Engen, Steinar; Lee, Aline Magdalena; Sæther, Bernt-Erik

    2018-02-01

    We analyze a spatial age-structured model with density regulation, age specific dispersal, stochasticity in vital rates and proportional harvesting. We include two age classes, juveniles and adults, where juveniles are subject to logistic density dependence. There are environmental stochastic effects with arbitrary spatial scales on all birth and death rates, and individuals of both age classes are subject to density independent dispersal with given rates and specified distributions of dispersal distances. We show how to simulate the joint density fields of the age classes and derive results for the spatial scales of all spatial autocovariance functions for densities. A general result is that the squared scale has an additive term equal to the squared scale of the environmental noise, corresponding to the Moran effect, as well as additive terms proportional to the dispersal rate and variance of dispersal distance for the age classes and approximately inversely proportional to the strength of density regulation. We show that the optimal harvesting strategy in the deterministic case is to harvest only juveniles when their relative value (e.g. financial) is large, and otherwise only adults. With increasing environmental stochasticity there is an interval of increasing length of values of juveniles relative to adults where both age classes should be harvested. Harvesting generally tends to increase all spatial scales of the autocovariances of densities. Copyright © 2017. Published by Elsevier Inc.

  12. 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.

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

    International Nuclear Information System (INIS)

    Loew, G.A.; Wang, J.

    1984-06-01

    When electrons or positrons in a bunch pass through the periodic structure of a linear accelerator, they leave behind them energy in the form of longitudinal wake fields. The longitudinal fields left behind by early particles in a bunch decrease the energy of later particles. For a linear collider, the energy spread introduced within the bunches by this beam loading effect must be minimized because it limits the degree to which the particles can be focused to a small spot due to chromatic effects in the final focus system. For example, for the SLC, the allowable energy spread is +-0.5%. 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 report 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

  14. 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

  15. Predators shape distribution and promote diversification of morphological defenses in Leucorrhinia , Odonata

    Science.gov (United States)

    Petrin, Zlatko; Schilling, Emily Gaenzle; Loftin, Cyndy; Johansson, Frank

    2010-01-01

    Predators strongly influence species assemblages and shape morphological defenses of prey. Interestingly, adaptations that constitute effective defenses against one type of predator may render the prey susceptible to other types of predators. Hence, prey may evolve different strategies to escape predation, which may facilitate adaptive radiation of prey organisms. Larvae of different species in the dragonfly genus Leucorrhinia have various morphological defenses. We studied the distribution of these larvae in relation to the presence of predatory fish. In addition, we examined the variation in morphological defenses within species with respect to the occurrence of fish. We found that well-defended species, those with more and longer spines, were more closely associated with habitats inhabited by predatory fish and that species with weakly developed morphological defenses were more abundant in habitats without fish. The species predominantly connected to lakes with or without fish, respectively, were not restricted to a single clade in the phylogeny of the genus. Our data is suggestive of phenotypic plasticity in morphological defense in three of the studied species since these species showed longer spines in lakes with fish. We suggest that adaptive phenotypic plasticity may have broadened the range of habitats accessible to Leucorrhinia. It may have facilitated colonization of new habitats with different types of predators, and ultimately, speciation through adaptive radiation.

  16. 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.

  17. A monolithic constant-fraction discriminator using distributed R-C delay-line shaping

    International Nuclear Information System (INIS)

    Simpson, M.L.; Young, G.R.; Xu, M.

    1995-01-01

    A monolithic, CMOS, constant-fraction discriminator (CFD) was fabricated in the Orbit Semiconductor, 1.2 μ N-well process. This circuit uses an on-chip, distributed, R-C delay-line to realize the constant-fraction shaping. The delay-line is constructed from a narrow, 500-μ serpentine layer of polysilicon above a wide, grounded, second layer of polysilicon. This R-C delay-line generates about 1.1 ns of delay for 5 ns risetime signals with a slope degradation of only ≅ 15% and an amplitude reduction of about 6.1%. The CFD also features an automatic walk adjustment. The entire circuit, including the delay line, has a 200 μ pitch and is 950 μ long. The walk for a 5 ns risetime signal was measured as ± 100 ps over the 100:1 dynamic range from -15 mV to -1.5 mV. to -1.5 V. The CFD consumes 15 mW

  18. 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

  19. Spatially-explicit estimation of geographical representation in large-scale species distribution datasets.

    Science.gov (United States)

    Kalwij, Jesse M; Robertson, Mark P; Ronk, Argo; Zobel, Martin; Pärtel, Meelis

    2014-01-01

    Much ecological research relies on existing multispecies distribution datasets. Such datasets, however, can vary considerably in quality, extent, resolution or taxonomic coverage. We provide a framework for a spatially-explicit evaluation of geographical representation within large-scale species distribution datasets, using the comparison of an occurrence atlas with a range atlas dataset as a working example. Specifically, we compared occurrence maps for 3773 taxa from the widely-used Atlas Florae Europaeae (AFE) with digitised range maps for 2049 taxa of the lesser-known Atlas of North European Vascular Plants. We calculated the level of agreement at a 50-km spatial resolution using average latitudinal and longitudinal species range, and area of occupancy. Agreement in species distribution was calculated and mapped using Jaccard similarity index and a reduced major axis (RMA) regression analysis of species richness between the entire atlases (5221 taxa in total) and between co-occurring species (601 taxa). We found no difference in distribution ranges or in the area of occupancy frequency distribution, indicating that atlases were sufficiently overlapping for a valid comparison. The similarity index map showed high levels of agreement for central, western, and northern Europe. The RMA regression confirmed that geographical representation of AFE was low in areas with a sparse data recording history (e.g., Russia, Belarus and the Ukraine). For co-occurring species in south-eastern Europe, however, the Atlas of North European Vascular Plants showed remarkably higher richness estimations. Geographical representation of atlas data can be much more heterogeneous than often assumed. Level of agreement between datasets can be used to evaluate geographical representation within datasets. Merging atlases into a single dataset is worthwhile in spite of methodological differences, and helps to fill gaps in our knowledge of species distribution ranges. Species distribution

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Study on plasma visible radiation spatial distribution at the TO-1 tokamak

    International Nuclear Information System (INIS)

    Molotkov, L.I.; Shvindt, N.N.

    1977-01-01

    The results of spatial distribution measurements of radiation intensities of spectral lines of hydrogen and light plasma impurities in the visible-light spectrum TO-1 tokamak are described. The method of electrochemical scanning with the help of rotating disk with notches was used. The experiments were carried out in the stable regime of discharge and in the regime with breakdown instability. In the stable regime absolute intensities of the spectral lines were measured. The concentration of radiating atoms and ions were calculated using the measured absolute intensities. Besides in order to determine the region in which the discharge appears in the cross section of the TO-1 chamber the spatial distributions of Hsub(β) neutral hydrogen spectral line in the initial stage of the discharge (0 9 cm -3 for the C(3) ion and anti nsub(0)=1.1x10 10 cm -3 for hydrogen atoms. The investigation into spatial distributions of the Hsub(β) line radiation in the initial stage of the filament formation showed that in the overwhelming majority of cases the discharge appears near the internal wall of the tokamak chamber

  5. 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.

  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 st