WorldWideScience

Sample records for random spatial distribution

  1. Spatial distribution

    DEFF Research Database (Denmark)

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

    2008-01-01

    influences the outcome of ecological processes. For instance, interactions between predator species and their prey can have widely different population impacts in different landscapes. At the very largest scales, the position and sizes of the entire range of species also follow characteristic patterns......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...

  2. A Permutation-Randomization Approach to Test the Spatial Distribution of Plant Diseases.

    Science.gov (United States)

    Lione, G; Gonthier, P

    2016-01-01

    The analysis of the spatial distribution of plant diseases requires the availability of trustworthy geostatistical methods. The mean distance tests (MDT) are here proposed as a series of permutation and randomization tests to assess the spatial distribution of plant diseases when the variable of phytopathological interest is categorical. A user-friendly software to perform the tests is provided. Estimates of power and type I error, obtained with Monte Carlo simulations, showed the reliability of the MDT (power > 0.80; type I error pathogens causing root rot on conifers was successfully performed by verifying the consistency between the MDT responses and previously published data. An application of the MDT was carried out to analyze the relation between the plantation density and the distribution of the infection of Gnomoniopsis castanea, an emerging fungal pathogen causing nut rot on sweet chestnut. Trees carrying nuts infected by the pathogen were randomly distributed in areas with different plantation densities, suggesting that the distribution of G. castanea was not related to the plantation density. The MDT could be used to analyze the spatial distribution of plant diseases both in agricultural and natural ecosystems.

  3. Spatial distribution of random velocity inhomogeneities in the western part of Nankai subduction zone

    Science.gov (United States)

    Takahashi, T.; Obana, K.; Yamamoto, Y.; Nakanishi, A.; Kodaira, S.; Kaneda, Y.

    2011-12-01

    In the Nankai trough, there are three seismogenic zones of megathrust earthquakes (Tokai, Tonankai and Nankai earthquakes). Lithospheric structures in and around these seismogenic zones are important for the studies on mutual interactions and synchronization of their fault ruptures. Recent studies on seismic wave scattering at high frequencies (>1Hz) make it possible to estimate 3D distributions of random inhomogeneities (or scattering coefficient) in the lithosphere, and clarified that random inhomogeneity is one of the important medium properties related to microseismicity and damaged structure near the fault zone [Asano & Hasegawa, 2004; Takahashi et al. 2009]. This study estimates the spatial distribution of the power spectral density function (PSDF) of random inhomogeneities the western part of Nankai subduction zone, and examines the relations with crustal velocity structure and seismic activity. Seismic waveform data used in this study are those recorded at seismic stations of Hi-net & F-net operated by NIED, and 160 ocean bottom seismographs (OBSs) deployed at Hyuga-nada region from Dec. 2008 to Jan. 2009. This OBS observation was conducted by JAMSTEC as a part of "Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes" funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. Spatial distribution of random inhomogeneities is estimated by the inversion analysis of the peak delay time of small earthquakes [Takahashi et al. 2009], where the peak delay time is defined as the time lag from the S-wave onset to its maximal amplitude arrival. We assumed the von Karman type functional form for the PSDF. Peak delay times are measured from root mean squared envelopes at 4-8Hz, 8-16Hz and 16-32Hz. Inversion result can be summarized as follows. Random inhomogeneities beneath the Quaternary volcanoes are characterized by strong inhomogeneities at small spatial scale (~ a few hundreds meter) and weak spectral gradient

  4. Discovery of Non-random Spatial Distribution of Impacts in the Stardust Cometary Collector

    Energy Technology Data Exchange (ETDEWEB)

    Westphal, A J; Bastien, R K; Borg, J; Bridges, J; Brownlee, D E; Burchell, M J; Cheng, A F; Clark, B C; Djouadi, Z; Floss, C; Franchi, I; Gainsforth, Z; Graham, G; Green, S F; Heck, P R; Horanyi, M; Hoppe, P; Horz, F P; Huth, J; Kearsley, A; Leroux, H; Marhas, K; Nakamura-Messenger, K; Sandford, S A; See, T H; Stadermann, F J; Teslich, N E; Tsitrin, S; Warren, J L; Wozniakiewicz, P J; Zolensky, M E

    2007-04-06

    We report the discovery that impacts in the Stardust cometary collector are not distributed randomly in the collecting media, but appear to be clustered on scales smaller than {approx} 10 cm. We also report the discovery of at least two populations of oblique tracks. We evaluated several hypotheses that could explain the observations. No hypothesis was consistent with all the observations, but the preponderance of evidence points toward at least one impact on the central Whipple shield of the spacecraft as the origin of both clustering and low-angle oblique tracks. High-angle oblique tracks unambiguously originate from a non-cometary impact on the spacecraft bus just forward of the collector.

  5. A Random Forest approach to predict the spatial distribution of sediment pollution in an estuarine system.

    Directory of Open Access Journals (Sweden)

    Eric S Walsh

    Full Text Available Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxyphenol (TCS, in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC (transport and fate proxy was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry and sand (transport and fate proxy were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary, which was validated with independent test samples. This decision-support tool performed well at the sub-estuary extent and provided the means to identify areas of concern and prioritize bay-wide sampling.

  6. The random field model of the spatial distribution of heavy vehicle loads on long-span bridges

    Science.gov (United States)

    Chen, Zhicheng; Bao, Yuequan; Li, Hui

    2016-04-01

    A stochastic model based on Markov random field is proposed to model the spatial distribution of vehicle loads on longspan bridges. The bridge deck is divided into a finite set of discrete grid cells, each cell has two states according to whether the cell is occupied by the heavy vehicle load or not, then a four-neighbor lattice-structured undirected graphical model with each node corresponding to a cell state variable is proposed to model the location distribution of heavy vehicle loads on the bridge deck. The node potential is defined to quantitatively describe the randomness of node state, and the edge potential is defined to quantitatively describe the correlation of the connected node pair. The junction tree algorithm is employed to obtain the systematic solutions of inference problems of the graphical model. A marked random variable is assigned to each node to represent the amplitude of the total weight of vehicle applied on the corresponding cell of the bridge deck. The rationality of the model is validated by a Monte Carlo simulation of a learned model based on monitored data of a cable-stayed bridge.

  7. A Random Forest Approach to Predict the Spatial Distribution of Sediment Pollution in an Estuarine System

    Science.gov (United States)

    Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment cont...

  8. Clustering, Randomness, and Regularity: Spatial Distributions and Human Performance on the Traveling Salesperson Problem and Minimum Spanning Tree Problem

    Science.gov (United States)

    Dry, Matthew J.; Preiss, Kym; Wagemans, Johan

    2012-01-01

    We investigated human performance on the Euclidean Traveling Salesperson Problem (TSP) and Euclidean Minimum Spanning Tree Problem (MST-P) in regards to a factor that has previously received little attention within the literature: the spatial distributions of TSP and MST-P stimuli. First, we describe a method for quantifying the relative degree of…

  9. Spatial Extent of Random Laser Modes

    NARCIS (Netherlands)

    van der Molen, K.L.; Tjerkstra, R.W.; Mosk, Allard; Lagendijk, Aart

    2007-01-01

    We have experimentally studied the distribution of the spatial extent of modes and the crossover from essentially single-mode to distinctly multimode behavior inside a porous gallium phosphide random laser. This system serves as a paragon for random lasers due to its exemplary high index contrast.

  10. Parallelization of a spatial random field characterization process using the Method of Anchored Distributions and the HTCondor high throughput computing system

    Science.gov (United States)

    Osorio-Murillo, C. A.; Over, M. W.; Frystacky, H.; Ames, D. P.; Rubin, Y.

    2013-12-01

    A new software application called MAD# has been coupled with the HTCondor high throughput computing system to aid scientists and educators with the characterization of spatial random fields and enable understanding the spatial distribution of parameters used in hydrogeologic and related modeling. MAD# is an open source desktop software application used to characterize spatial random fields using direct and indirect information through Bayesian inverse modeling technique called the Method of Anchored Distributions (MAD). MAD relates indirect information with a target spatial random field via a forward simulation model. MAD# executes inverse process running the forward model multiple times to transfer information from indirect information to the target variable. MAD# uses two parallelization profiles according to computational resources available: one computer with multiple cores and multiple computers - multiple cores through HTCondor. HTCondor is a system that manages a cluster of desktop computers for submits serial or parallel jobs using scheduling policies, resources monitoring, job queuing mechanism. This poster will show how MAD# reduces the time execution of the characterization of random fields using these two parallel approaches in different case studies. A test of the approach was conducted using 1D problem with 400 cells to characterize saturated conductivity, residual water content, and shape parameters of the Mualem-van Genuchten model in four materials via the HYDRUS model. The number of simulations evaluated in the inversion was 10 million. Using the one computer approach (eight cores) were evaluated 100,000 simulations in 12 hours (10 million - 1200 hours approximately). In the evaluation on HTCondor, 32 desktop computers (132 cores) were used, with a processing time of 60 hours non-continuous in five days. HTCondor reduced the processing time for uncertainty characterization by a factor of 20 (1200 hours reduced to 60 hours.)

  11. Selecting Optimal Random Forest Predictive Models: A Case Study on Predicting the Spatial Distribution of Seabed Hardness

    Science.gov (United States)

    Li, Jin; Tran, Maggie; Siwabessy, Justy

    2016-01-01

    Spatially continuous predictions of seabed hardness are important baseline environmental information for sustainable management of Australia’s marine jurisdiction. Seabed hardness is often inferred from multibeam backscatter data with unknown accuracy and can be inferred from underwater video footage at limited locations. In this study, we classified the seabed into four classes based on two new seabed hardness classification schemes (i.e., hard90 and hard70). We developed optimal predictive models to predict seabed hardness using random forest (RF) based on the point data of hardness classes and spatially continuous multibeam data. Five feature selection (FS) methods that are variable importance (VI), averaged variable importance (AVI), knowledge informed AVI (KIAVI), Boruta and regularized RF (RRF) were tested based on predictive accuracy. Effects of highly correlated, important and unimportant predictors on the accuracy of RF predictive models were examined. Finally, spatial predictions generated using the most accurate models were visually examined and analysed. This study confirmed that: 1) hard90 and hard70 are effective seabed hardness classification schemes; 2) seabed hardness of four classes can be predicted with a high degree of accuracy; 3) the typical approach used to pre-select predictive variables by excluding highly correlated variables needs to be re-examined; 4) the identification of the important and unimportant predictors provides useful guidelines for further improving predictive models; 5) FS methods select the most accurate predictive model(s) instead of the most parsimonious ones, and AVI and Boruta are recommended for future studies; and 6) RF is an effective modelling method with high predictive accuracy for multi-level categorical data and can be applied to ‘small p and large n’ problems in environmental sciences. Additionally, automated computational programs for AVI need to be developed to increase its computational efficiency and

  12. Selecting Optimal Random Forest Predictive Models: A Case Study on Predicting the Spatial Distribution of Seabed Hardness.

    Directory of Open Access Journals (Sweden)

    Jin Li

    Full Text Available Spatially continuous predictions of seabed hardness are important baseline environmental information for sustainable management of Australia's marine jurisdiction. Seabed hardness is often inferred from multibeam backscatter data with unknown accuracy and can be inferred from underwater video footage at limited locations. In this study, we classified the seabed into four classes based on two new seabed hardness classification schemes (i.e., hard90 and hard70. We developed optimal predictive models to predict seabed hardness using random forest (RF based on the point data of hardness classes and spatially continuous multibeam data. Five feature selection (FS methods that are variable importance (VI, averaged variable importance (AVI, knowledge informed AVI (KIAVI, Boruta and regularized RF (RRF were tested based on predictive accuracy. Effects of highly correlated, important and unimportant predictors on the accuracy of RF predictive models were examined. Finally, spatial predictions generated using the most accurate models were visually examined and analysed. This study confirmed that: 1 hard90 and hard70 are effective seabed hardness classification schemes; 2 seabed hardness of four classes can be predicted with a high degree of accuracy; 3 the typical approach used to pre-select predictive variables by excluding highly correlated variables needs to be re-examined; 4 the identification of the important and unimportant predictors provides useful guidelines for further improving predictive models; 5 FS methods select the most accurate predictive model(s instead of the most parsimonious ones, and AVI and Boruta are recommended for future studies; and 6 RF is an effective modelling method with high predictive accuracy for multi-level categorical data and can be applied to 'small p and large n' problems in environmental sciences. Additionally, automated computational programs for AVI need to be developed to increase its computational efficiency and

  13. Mapping Spatial Distribution of Larch Plantations from Multi-Seasonal Landsat-8 OLI Imagery and Multi-Scale Textures Using Random Forests

    Directory of Open Access Journals (Sweden)

    Tian Gao

    2015-02-01

    Full Text Available The knowledge about spatial distribution of plantation forests is critical for forest management, monitoring programs and functional assessment. This study demonstrates the potential of multi-seasonal (spring, summer, autumn and winter Landsat-8 Operational Land Imager imageries with random forests (RF modeling to map larch plantations (LP in a typical plantation forest landscape in North China. The spectral bands and two types of textures were applied for creating 675 input variables of RF. An accuracy of 92.7% for LP, with a Kappa coefficient of 0.834, was attained using the RF model. A RF-based importance assessment reveals that the spectral bands and bivariate textural features calculated by pseudo-cross variogram (PC strongly promoted forest class-separability, whereas the univariate textural features influenced weakly. A feature selection strategy eliminated 93% of variables, and then a subset of the 47 most essential variables was generated. In this subset, PC texture derived from summer and winter appeared the most frequently, suggesting that this variability in growing peak season and non-growing season can effectively enhance forest class-separability. A RF classifier applied to the subset led to 91.9% accuracy for LP, with a Kappa coefficient of 0.829. This study provides an insight into approaches for discriminating plantation forests with phenological behaviors.

  14. Spatial distribution of impact craters on Deimos

    Science.gov (United States)

    Hirata, Naoyuki

    2017-05-01

    Deimos, one of the Martian moons, has numerous impact craters. However, it is unclear whether crater saturation has been reached on this satellite. To address this issue, we apply a statistical test known as nearest-neighbor analysis to analyze the crater distribution of Deimos. When a planetary surface such as the Moon is saturated with impact craters, the spatial distribution of craters is generally changed from random to more ordered. We measured impact craters on Deimos from Viking and HiRISE images and found (1) that the power law of the size-frequency distribution of the craters is approximately -1.7, which is significantly shallower than those of potential impactors, and (2) that the spatial distribution of craters over 30 m in diameter cannot be statistically distinguished from completely random distribution, which indicates that the surface of Deimos is inconsistent with a surface saturated with impact craters. Although a crater size-frequency distribution curve with a slope of -2 is generally interpreted as indicating saturation equilibrium, it is here proposed that two competing mechanisms, seismic shaking and ejecta emplacement, have played a major role in erasing craters on Deimos and are therefore responsible for the shallow slope of this curve. The observed crater density may have reached steady state owing to the obliterations induced by the two competing mechanisms. Such an occurrence indicates that the surface is saturated with impact craters despite the random distribution of craters on Deimos. Therefore, this work proposes that the age determined by the current craters on Deimos reflects neither the age of Deimos itself nor that of the formation of the large concavity centered at its south pole because craters should be removed by later impacts. However, a few of the largest craters on Deimos may be indicative of the age of the south pole event.

  15. Process of random distributions : classification and prediction ...

    African Journals Online (AJOL)

    Dirichlet random distribution. The parameter of this process can be the distribution of any usual such as the (multifractional) Brownian motion. We also extend Kraft random distribution to the continuous time case. We give an application in ...

  16. Dengue Vectors and their Spatial Distribution.

    Science.gov (United States)

    Higa, Yukiko

    2011-12-01

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

  17. Spatial distribution of suicide in Queensland, Australia

    OpenAIRE

    Tong Shilu; Qi Xin; Hu Wenbiao

    2010-01-01

    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. Meth...

  18. 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.

  19. 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.

  20. Spatial distribution of aquatic insects

    DEFF Research Database (Denmark)

    Iversen, Lars Lønsmann

    Species associated with freshwater ecosystems are currently undergoing severe global declines and freshwater ecosystems are regarded as some of the most endangered ecosystems in the world. These declines are a consequence of decades of human overexploitation, pollution and climate change. If adeq......Species associated with freshwater ecosystems are currently undergoing severe global declines and freshwater ecosystems are regarded as some of the most endangered ecosystems in the world. These declines are a consequence of decades of human overexploitation, pollution and climate change...... 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...

  1. 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.

  2. Multicriteria optimization of the spatial dose distribution

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-15

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

  3. Spatial-mode conversion using random diffuser and spatial light modulator for reduction of modal crosstalk

    Science.gov (United States)

    Ishii, Koki; Okamoto, Atsushi; Tsuritani, Takehiro; Wakayama, Yuta; Goto, Yuta; Tomita, Akihisa

    2016-02-01

    The mode-division multiplexing (MDM) technique enables the transmission of multiple signals within a multi-mode fiber (MMF) or a few-mode fiber (FMF). To construct an efficient and flexible MDM network in the same way as a wavelength-division multiplexing network, a mode conversion method with low modal crosstalk is required for switching between arbitrary spatial modes. However, in general, modal crosstalk is strongly dependent on the intensity pattern before mode conversion, and it is increased particularly for higher order modes. In order to reduce modal crosstalk, we propose a method using a random diffuser and a spatial light modulator (SLM). In the proposed method, firstly, the input spatial mode is dispersed uniformly by the random diffuser. Subsequently, the diffused phase distribution is canceled and converted into the desired spatial mode by the SLM, which displays phase difference between desired and diffused modes. Consequently, every spatial mode can be evenly converted into a desired mode. Here, we numerically simulate and confirm that the proposed method can reduce modal crosstalk compared to the conversion method without the random diffuser.

  4. Spatial heterogeneity in distribution and ecology of Western Palearctic birds.

    Science.gov (United States)

    Møller, A P; Soler, J J; Vivaldi, M Martín

    2010-09-01

    Species vary in abundance and heterogeneity of spatial distribution, and the ecological and evolutionary consequences of such variability are poorly known. Evolutionary adaptation to heterogeneously distributed resources may arise from local adaptation with individuals of such locally adapted populations rarely dispersing long distances and hence having small populations and small overall ranges. We quantified mean population density and spatial heterogeneity in population density of 197 bird species across 12 similarly sized regions in the Western Palearctic. Variance in population density among regions differed significantly from a Poisson distribution, suggesting that random processes cannot explain the observed patterns. National estimates of means and variances in population density were positively correlated with continental estimates, suggesting that means and variances were maintained across spatial scales. We used Morisita's index of population abundance as an estimate of heterogeneity in distribution among regions to test a number of predictions. Heterogeneously distributed passerine bird species as reflected by Morisita's index had small populations, low population densities, and small breeding ranges. Their breeding populations had been consistently maintained at low levels for considerable periods of time, because the degree of genetic variation in a subsample of non-passerines and passerines was significantly negatively related to heterogeneity in distribution. Heterogeneously distributed passerine species were not more often habitat specialists than homogeneously distributed species. Furthermore, heterogeneously distributed passerine species had high annual adult survival rates but did not differ in annual fecundity from homogeneously distributed species. Heterogeneously distributed passerine species rarely colonized urban habitats. Finally, homogeneously distributed bird species were hosts to a greater diversity of blood parasite species than

  5. Spatial distribution and packing of xylem conduits.

    Science.gov (United States)

    Martínez-Vilalta, Jordi; Mencuccini, Maurizio; Alvarez, Xavier; Camacho, Juan; Loepfe, Lasse; Piñol, Josep

    2012-07-01

    The hydraulic properties of the xylem determine the ability of plants to transport water from the soil to the leaves and to cope with important stress factors such as frost and drought. Hydraulic properties have usually been studied as a function of the anatomy of xylem conduits and their pits, but recent studies have proposed that system-level properties, related to the topology of the xylem network, may also play a role. Here we study how the spatial arrangement of conduits in xylem cross sections affects the relationship between mean conduit lumen area and conduit density (packing function) across species. Point pattern analysis was used to describe the spatial distribution of xylem conduits in 97 woody species. The effect of conduit aggregation on the packing function was tested using phylogenetic generalized least squares. A hydraulic model with an explicit description of the topology of the xylem network was used to interpret the functional significance of our findings. The spatial arrangement of conduits affected the packing function across species, so that species with aggregated distributions tended to have lower conduit densities for a given conduit size and lower conduit lumen fractions. According to our modeling results, the higher conduit-to-conduit connectivity of species with aggregated distributions allows them to achieve higher hydraulic conductivity. Species with aggregated conduits, however, pay a cost in terms of increased vulnerability to embolism. The spatial arrangement of conduits affects the fundamental structural and functional attributes of the xylem.

  6. Spatially random models, estimation theory, and robot arm dynamics

    Science.gov (United States)

    Rodriguez, G.

    1987-01-01

    Spatially random models provide an alternative to the more traditional deterministic models used to describe robot arm dynamics. These alternative models can be used to establish a relationship between the methodologies of estimation theory and robot dynamics. A new class of algorithms for many of the fundamental robotics problems of inverse and forward dynamics, inverse kinematics, etc. can be developed that use computations typical in estimation theory. The algorithms make extensive use of the difference equations of Kalman filtering and Bryson-Frazier smoothing to conduct spatial recursions. The spatially random models are very easy to describe and are based on the assumption that all of the inertial (D'Alembert) forces in the system are represented by a spatially distributed white-noise model. The models can also be used to generate numerically the composite multibody system inertia matrix. This is done without resorting to the more common methods of deterministic modeling involving Lagrangian dynamics, Newton-Euler equations, etc. These methods make substantial use of human knowledge in derivation and minipulation of equations of motion for complex mechanical systems.

  7. Cascading failures in spatially-embedded random networks.

    Science.gov (United States)

    Asztalos, Andrea; Sreenivasan, Sameet; Szymanski, Boleslaw K; Korniss, Gyorgy

    2014-01-01

    Cascading failures constitute an important vulnerability of interconnected systems. Here we focus on the study of such failures on networks in which the connectivity of nodes is constrained by geographical distance. Specifically, we use random geometric graphs as representative examples of such spatial networks, and study the properties of cascading failures on them in the presence of distributed flow. The key finding of this study is that the process of cascading failures is non-self-averaging on spatial networks, and thus, aggregate inferences made from analyzing an ensemble of such networks lead to incorrect conclusions when applied to a single network, no matter how large the network is. We demonstrate that this lack of self-averaging disappears with the introduction of a small fraction of long-range links into the network. We simulate the well studied preemptive node removal strategy for cascade mitigation and show that it is largely ineffective in the case of spatial networks. We introduce an altruistic strategy designed to limit the loss of network nodes in the event of a cascade triggering failure and show that it performs better than the preemptive strategy. Finally, we consider a real-world spatial network viz. a European power transmission network and validate that our findings from the study of random geometric graphs are also borne out by simulations of cascading failures on the empirical network.

  8. 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...

  9. Spatial distribution maps for benthic communities

    DEFF Research Database (Denmark)

    Sørensen, Per S.

    1999-01-01

    The application of hydroacoustic measurements for preparation of spatial distribution maps of benthic communities is reported. For the present study common mussels (Mytilus edulis), neptune grass (Posidonia oceanica) and Cymodocea nodosa, serving as canonical species of many European marine...... and the Meditteranean. combination of geostatistical methods for spatial interpolation of the echo sounder observations and a set of classification rules, based on discriminant analysis of the feature space of=20 the observations, is found to yield reliable distribution maps when compared to groundtruth data. The data......-driven methodology developed is shown to be adaptive to instationarities in the echo sounder observations and is recommended as a substantial improvement of existing methods of sea floor mapping based on echo sounder data. Elaborations of the developed methodology are studied, comprising the use of geostatistical...

  10. Visibility graphs of random scalar fields and spatial data

    Science.gov (United States)

    Lacasa, Lucas; Iacovacci, Jacopo

    2017-07-01

    We extend the family of visibility algorithms to map scalar fields of arbitrary dimension into graphs, enabling the analysis of spatially extended data structures as networks. We introduce several possible extensions and provide analytical results on the topological properties of the graphs associated to different types of real-valued matrices, which can be understood as the high and low disorder limits of real-valued scalar fields. In particular, we find a closed expression for the degree distribution of these graphs associated to uncorrelated random fields of generic dimension. This result holds independently of the field's marginal distribution and it directly yields a statistical randomness test, applicable in any dimension. We showcase its usefulness by discriminating spatial snapshots of two-dimensional white noise from snapshots of a two-dimensional lattice of diffusively coupled chaotic maps, a system that generates high dimensional spatiotemporal chaos. The range of potential applications of this combinatorial framework includes image processing in engineering, the description of surface growth in material science, soft matter or medicine, and the characterization of potential energy surfaces in chemistry, disordered systems, and high energy physics. An illustration on the applicability of this method for the classification of the different stages involved in carcinogenesis is briefly discussed.

  11. Spatial paradigms of lotic diatom distribution: A landscape ecology perspective

    Science.gov (United States)

    Passy, S.I.

    2001-01-01

    Spatial distributional patterns of benthic diatoms and their relation to current velocity were investigated in an unshaded cobble-bottom reach of White Creek (Washington County, NY). On 27 August 1999, diatoms were sampled and current velocity and depth were measured on a regular square sampling grid with a grain size of 0.01 m2, interval of 0.5 m, and extent of 16 m2. The relative abundance of the 18 common diatom species enumerated in the 81 samples was subjected to detrended correspondence analysis (DCA). The first axis (DCA1) explained 51% of the variance in diatom data and separated the samples according to current regimes. The spatial autocorrelation of DCA1 sample scores in deposition and erosion regions of White Creek was determined by Moran's I statistic to indicate patch size. In White Creek the patch length of all diatom communities was more than 3.1 m, whereas the patch width was 1 m in the deposition region and 0.5 m in the erosion region. There were 5 dominant diatom taxa, Achnanthes minutissima Ku??tz. et vars, Fragilaria capucina Dezmazie??res et vars, F. crotonensis Kitt., Diatoma vulgaris Bory, and Synedra ulna (Nitz.) Ehr. et vars. The patch length of the dominant species varied from 1 to more than 4.1 m, whereas the patch width, if defined, was 0.5 m. Achnanthes minutissima and F. capucina, the two diatom species with the highest relative abundance, displayed spatially structured patches of low abundance and comparatively random patches of high abundance, suggesting broad scale abiotic control of species performance in low abundance regions and finer scale biotic control of high abundance areas. Another objective of this study was to test the hypothesis that higher current velocities, which generally impede immigration, would increase randomness and complexity (i.e. homogeneity of diatom distributional patterns). The spatial complexity in low versus high velocity transects was determined by calculating the respective fractal dimension (D) of DCA

  12. 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.

  13. Revised spatially distributed global livestock emissions

    Science.gov (United States)

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

    2015-12-01

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

  14. Spatial distribution of the attentional blink

    Directory of Open Access Journals (Sweden)

    FENG eDU

    2011-12-01

    Full Text Available In the present study subjects viewed streams of rapid serially presented characters and searched for a target digit. After presentation of the target digit, a second target consisting of an orientation singleton (Experiment 1 or a second digit (Experiment 2 was presented at one of several distances from the first target. The attentional blink impaired performance on the second target with the effect being strongest at distances somewhat removed from the first target location. These results are consistent with lateral inhibition theory and help to resolve some fundamental questions about the spatial distribution of the attentional blink.

  15. Sampling design for spatially distributed hydrogeologic and environmental processes

    Science.gov (United States)

    Christakos, G.; Olea, R.A.

    1992-01-01

    A methodology for the design of sampling networks over space is proposed. The methodology is based on spatial random field representations of nonhomogeneous natural processes, and on optimal spatial estimation techniques. One of the most important results of random field theory for physical sciences is its rationalization of correlations in spatial variability of natural processes. This correlation is extremely important both for interpreting spatially distributed observations and for predictive performance. The extent of site sampling and the types of data to be collected will depend on the relationship of subsurface variability to predictive uncertainty. While hypothesis formulation and initial identification of spatial variability characteristics are based on scientific understanding (such as knowledge of the physics of the underlying phenomena, geological interpretations, intuition and experience), the support offered by field data is statistically modelled. This model is not limited by the geometric nature of sampling and covers a wide range in subsurface uncertainties. A factorization scheme of the sampling error variance is derived, which possesses certain atttactive properties allowing significant savings in computations. By means of this scheme, a practical sampling design procedure providing suitable indices of the sampling error variance is established. These indices can be used by way of multiobjective decision criteria to obtain the best sampling strategy. Neither the actual implementation of the in-situ sampling nor the solution of the large spatial estimation systems of equations are necessary. The required values of the accuracy parameters involved in the network design are derived using reference charts (readily available for various combinations of data configurations and spatial variability parameters) and certain simple yet accurate analytical formulas. Insight is gained by applying the proposed sampling procedure to realistic examples related

  16. Simulation of the K-function in the analysis of spatial clustering for non-randomly distributed locations-Exemplified by bovine virus diarrhoea virus (BVDV) infection in Denmark

    DEFF Research Database (Denmark)

    Ersbøll, Annette Kjær; Ersbøll, Bjarne Kjær

    2009-01-01

    The K-function is often used to detect spatial clustering in spatial point processes, e.g. clustering of infected herds. Clustering is identified by testing the observed K-function for complete spatial randomness modelled, e.g. by a homogeneous Poisson process. The approach provides information a...... of the herd locations in general. The approach also overcomes edge effects and problems with complex shapes of the study region. An application to bovine virus diarrhoea virus (BVDV) infection in Denmark is described....

  17. Spatially resolved elemental distributions in articular cartilage

    Energy Technology Data Exchange (ETDEWEB)

    Reinert, T. E-mail: reinert@physik.uni-leipzig.de; Reibetanz, U.; Vogt, J.; Butz, T.; Werner, A.; Gruender, W

    2001-07-01

    In this study, the nuclear microprobe technique is employed to analyse the chemistry of joint cartilage in order to correlate internal structures of the collagen network with the elemental distribution. The samples were taken from pig's knee joint. 30 {mu}m thick coronar cross-sections were prepared by means of cryosectioning and freeze-drying. We performed simultaneously particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA). Thus we obtained spatially resolved distributions of the elements H, C, N, O, P, S, Cl, K and Ca. The main components of the organic matrix are H, C, N and O. It was shown that their relations vary with the cartilage structures. It could be shown that zones with aligned collagen fibrils contain less sulphur and potassium but more chlorine. The higher chlorine concentration is remarkable because newest biochemical studies found that hypochloric acid is involved in cartilage degradation. Furthermore, the calcium distribution is still of great interest. Its correlation to structural changes inside the cartilage is still being discussed. It could be disproved that zones of higher calcium concentration are related to the aligned structures of the collagen network.

  18. Spatially resolved elemental distributions in articular cartilage

    Science.gov (United States)

    Reinert, T.; Reibetanz, U.; Vogt, J.; Butz, T.; Werner, A.; Gründer, W.

    2001-07-01

    In this study, the nuclear microprobe technique is employed to analyse the chemistry of joint cartilage in order to correlate internal structures of the collagen network with the elemental distribution. The samples were taken from pig's knee joint. 30 μm thick coronar cross-sections were prepared by means of cryosectioning and freeze-drying. We performed simultaneously particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA). Thus we obtained spatially resolved distributions of the elements H, C, N, O, P, S, Cl, K and Ca. The main components of the organic matrix are H, C, N and O. It was shown that their relations vary with the cartilage structures. It could be shown that zones with aligned collagen fibrils contain less sulphur and potassium but more chlorine. The higher chlorine concentration is remarkable because newest biochemical studies found that hypochloric acid is involved in cartilage degradation. Furthermore, the calcium distribution is still of great interest. Its correlation to structural changes inside the cartilage is still being discussed. It could be disproved that zones of higher calcium concentration are related to the aligned structures of the collagen network.

  19. Properties and spatial distribution of galaxy superclusters

    Science.gov (United States)

    Liivamägi, Lauri Juhan

    2017-01-01

    Astronomy is a science that can offer plenty of unforgettable imagery, and the large-scale distribution of galaxies is no exception. Among the first features the viewer's eye is likely to be drawn to, are large concentrations of galaxies - galaxy superclusters, contrasting to the seemingly empty regions beside them. Superclusters can extend from tens to over hundred megaparsecs, they contain from hundreds to thousands of galaxies, and many galaxy groups and clusters. Unlike galaxy clusters, superclusters are clearly unrelaxed systems, not gravitationally bound as crossing times exceed the age of the universe, and show little to no radial symmetry. Superclusters, as part of the large-scale structure, are sensitive to the initial power spectrum and the following evolution. They are massive enough to leave an imprint on the cosmic microwave background radiation. Superclusters can also provide an unique environment for their constituent galaxies and galaxy clusters. In this study we used two different observational and one simulated galaxy samples to create several catalogues of structures that, we think, correspond to what are generally considered galaxy superclusters. Superclusters were delineated as continuous over-dense regions in galaxy luminosity density fields. When calculating density fields several corrections were applied to remove small-scale redshift distortions and distance-dependent selection effects. Resulting catalogues of objects display robust statistical properties, showing that flux-limited galaxy samples can be used to create nearly volume-limited catalogues of superstructures. Generally, large superclusters can be regarded as massive, often branching filamentary structures, that are mainly characterised by their length. Smaller superclusters, on the other hand, can display a variety of shapes. Spatial distribution of superclusters shows large-scale variations, with high-density concentrations often found in semi-regularly spaced groups. Future

  20. Spatial and temporal distribution of natural disasters

    Directory of Open Access Journals (Sweden)

    Cvetković Vladimir M.

    2014-01-01

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

  1. The spatial distribution of Mustelidae in France.

    Directory of Open Access Journals (Sweden)

    Clément Calenge

    Full Text Available We estimated the spatial distribution of 6 Mustelidae species in France using the data collected by the French national hunting and wildlife agency under the "small carnivorous species logbooks" program. The 1500 national wildlife protection officers working for this agency spend 80% of their working time traveling in the spatial area in which they have authority. During their travels, they occasionally detect dead or living small and medium size carnivorous animals. Between 2002 and 2005, each car operated by this agency was equipped with a logbook in which officers recorded information about the detected animals (species, location, dead or alive, date. Thus, more than 30000 dead or living animals were detected during the study period. Because a large number of detected animals in a region could have been the result of a high sampling pressure there, we modeled the number of detected animals as a function of the sampling effort to allow for unbiased estimation of the species density. For dead animals -- mostly roadkill -- we supposed that the effort in a given region was proportional to the distance traveled by the officers. For living animals, we had no way to measure the sampling effort. We demonstrated that it was possible to use the whole dataset (dead and living animals to estimate the following: (i the relative density -- i.e., the density multiplied by an unknown constant -- of each species of interest across the different French agricultural regions, (ii the sampling effort for living animals for each region, and (iii the relative detection probability for various species of interest.

  2. Electrospun dye-doped fiber networks: lasing emission from randomly distributed cavities

    DEFF Research Database (Denmark)

    Krammer, Sarah; Vannahme, Christoph; Smith, Cameron

    2015-01-01

    Dye-doped polymer fiber networks fabricated with electrospinning exhibit comb-like laser emission. We identify randomly distributed ring resonators being responsible for lasing emission by making use of spatially resolved spectroscopy. Numerical simulations confirm this result quantitatively....

  3. Improved approximation of spatial light distribution.

    Directory of Open Access Journals (Sweden)

    David Kaljun

    Full Text Available The rapid worldwide evolution of LEDs as light sources has brought new challenges, which means that new methods are needed and new algorithms have to be developed. Since the majority of LED luminaries are of the multi-source type, established methods for the design of light engines cannot be used in the design of LED light engines. This is because in the latter case what is involved is not just the design of a good reflector or projector lens, but the design of several lenses which have to work together in order to achieve satisfactory results. Since lenses can also be bought off the shelf from several manufacturers, it should be possible to combine together different off the shelf lenses in order to design a good light engine. However, with so many different lenses to choose from, it is almost impossible to find an optimal combination by hand, which means that some optimization algorithms need to be applied. In order for them to work properly, it is first necessary to describe the input data (i.e. spatial light distribution in a functional form using as few as possible parameters. In this paper the focus is on the approximation of the input data, and the implementation of the well-known mathematical procedure for the separation of linear and nonlinear parameters, which can provide a substantial increase in performance.

  4. Wave speed in excitable random networks with spatially constrained connections.

    Directory of Open Access Journals (Sweden)

    Nikita Vladimirov

    Full Text Available Very fast oscillations (VFO in neocortex are widely observed before epileptic seizures, and there is growing evidence that they are caused by networks of pyramidal neurons connected by gap junctions between their axons. We are motivated by the spatio-temporal waves of activity recorded using electrocorticography (ECoG, and study the speed of activity propagation through a network of neurons axonally coupled by gap junctions. We simulate wave propagation by excitable cellular automata (CA on random (Erdös-Rényi networks of special type, with spatially constrained connections. From the cellular automaton model, we derive a mean field theory to predict wave propagation. The governing equation resolved by the Fisher-Kolmogorov PDE fails to describe wave speed. A new (hyperbolic PDE is suggested, which provides adequate wave speed v( that saturates with network degree , in agreement with intuitive expectations and CA simulations. We further show that the maximum length of connection is a much better predictor of the wave speed than the mean length. When tested in networks with various degree distributions, wave speeds are found to strongly depend on the ratio of network moments / rather than on mean degree , which is explained by general network theory. The wave speeds are strikingly similar in a diverse set of networks, including regular, Poisson, exponential and power law distributions, supporting our theory for various network topologies. Our results suggest practical predictions for networks of electrically coupled neurons, and our mean field method can be readily applied for a wide class of similar problems, such as spread of epidemics through spatial networks.

  5. GIS spatial data partitioning method for distributed data processing

    Science.gov (United States)

    Zhou, Yan; Zhu, Qing; Zhang, Yeting

    2007-11-01

    Spatial data partitioning strategy plays an important role in GIS spatial data distributed storage and processing, its key problem is how to partition spatial data to distributed nodes in network environment. Existing main spatial data partitioning methods doesn't consider spatial locality and unstructured variable length characteristics of spatial data, these methods simply partition spatial data based on one or more attributes value that could result in storage capacity imbalance between distributed processing nodes. Aiming at these, we point out the two basic principles that spatial data partitioning should meet to in this paper. We propose a new spatial data partitioning method based on hierarchical decomposition method of low order Hilbert space-filling curve, which could avoid excessively intensive space partitioning by hierarchically decomposing subspaces. The proposed method uses Hilbert curve to impose a linear ordering on the multidimensional spatial objects, and partition the spatial objects according to this ordering. Experimental results show the proposed spatial data partitioning method not only achieves better storage load balance between distributed nodes, but also keeps well spatial locality of data objects after partitioning.

  6. Dynamical properties of the spatial distribution of snow

    Directory of Open Access Journals (Sweden)

    T. Skaugen

    2003-01-01

    Full Text Available A simulation exercise has been performed to study the temporal development of snow covered area and the spatial distribution of snow-water equivalent (SWE. Special consideration has been paid to how the properties of the spatial statistical distribution of SWE change as a response to accumulation and ablation events. A distributed rainfall-runoff model at resolution 1 x 1 km2 has been run with time series of precipitation and temperature fields of the same spatial resolution derived from the atmospheric model HIRLAM. The precipitation fields are disaggregated and the temperature fields are interpolated. Time series of the spatial distribution of snow-water equivalent and snow-covered area for three seasons for a catchment in Norway is generated. The catchment is of size 3085 km2 and two rectangular sub-areas of 484 km2 are located within the larger catchment. The results show that the shape of the spatial distribution of SWE for all three areas changes during winter. The distribution is very skewed at the start of the accumulation season but then the skew decreases and, as the ablation season sets in, the spatial distribution again becomes more skewed with a maximum near the end of the ablation season. For one of the sub-areas, a consistently more skewed distribution of SWE is found, related to higher variability in precipitation. This indicates that observed differences in the spatial distribution of snow between alpine and forested areas can result from differences in the spatial variability of precipitation. The results obtained from the simulation exercise are consistent with modelling the spatial distribution of SWE as summations of a gamma distributed variable. Keywords: Snow, SWE, spatial distribution, simulated hydrometeorological fields

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

    African Journals Online (AJOL)

    Spatial Distribution and Accessibility of Health Facilities in Akwa Ibom State, Nigeria. ... Ethiopian Journal of Environmental Studies and Management ... The attainment of this goal is a function of the spatial pattern of distribution of healthcare facilities and a measure of the degree of accessibility to healthcare services.

  8. Spatial distribution of nematodes at organic and conventional crop ...

    African Journals Online (AJOL)

    An overview of the spatial distribution of nematodes can help the design of targeted, site-specific management strategies. This paper assessed and compared the spatial distribution of nematode population in an organic crop field and a conventional crop field using Inverse Distance Weighted (IDW) and ordinary Kriging ...

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

    African Journals Online (AJOL)

    The development of educational infrastructure is a pre-requisite to National development in all its ramifications. Accordingly, this paper assesses the spatial distribution of Government Owned Secondary Schools (GOSS) in the Zaria Area. It reveals that the spatial distribution of Government Owned Secondary Schools in ...

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

    Science.gov (United States)

    Borisovna, L; Velez, F

    1991-12-01

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

  11. Stochastic geometry, spatial statistics and random fields models and algorithms

    CERN Document Server

    2015-01-01

    Providing a graduate level introduction to various aspects of stochastic geometry, spatial statistics and random fields, this volume places a special emphasis on fundamental classes of models and algorithms as well as on their applications, for example in materials science, biology and genetics. This book has a strong focus on simulations and includes extensive codes in Matlab and R, which are widely used in the mathematical community. It can be regarded as a continuation of the recent volume 2068 of Lecture Notes in Mathematics, where other issues of stochastic geometry, spatial statistics and random fields were considered, with a focus on asymptotic methods.

  12. Raney Distributions and Random Matrix Theory

    Science.gov (United States)

    Forrester, Peter J.; Liu, Dang-Zheng

    2015-03-01

    Recent works have shown that the family of probability distributions with moments given by the Fuss-Catalan numbers permit a simple parameterized form for their density. We extend this result to the Raney distribution which by definition has its moments given by a generalization of the Fuss-Catalan numbers. Such computations begin with an algebraic equation satisfied by the Stieltjes transform, which we show can be derived from the linear differential equation satisfied by the characteristic polynomial of random matrix realizations of the Raney distribution. For the Fuss-Catalan distribution, an equilibrium problem characterizing the density is identified. The Stieltjes transform for the limiting spectral density of the singular values squared of the matrix product formed from inverse standard Gaussian matrices, and standard Gaussian matrices, is shown to satisfy a variant of the algebraic equation relating to the Raney distribution. Supported on , we show that it too permits a simple functional form upon the introduction of an appropriate choice of parameterization. As an application, the leading asymptotic form of the density as the endpoints of the support are approached is computed, and is shown to have some universal features.

  13. On the spatial distribution of magnetic fields on the solar surface

    Science.gov (United States)

    Tao, L.; Du, Y.; Rosner, R.; Cattaneo, F.

    1995-01-01

    Recent measurements of solar surface magnetic fields suggest that the spatial distribution of these fields is fractal. In order to understand the physical basis for such geometric complexity, we study here the advection of magnetic flux tubes relatively simple random motions on the surface of a fluid and investigate the spatial statistics of the resulting surface field. While this study does not directly address the question of why solar surface fields have the observed spatial structure, it is designed to build our intuition about how surface flows lead to complex spatial structuring of magnetic fields. As part of our study, we discuss the various methods by which one can describe the spatial distribution of the surface magnetic flux and relate them mathematically; this turns out to be a crucial point of our work since, as we show, a number of previous analyses have misinterpreted the analysis procedures for determining fractal dimensions. Our principal result is the explicit demonstration that simple random flows lead to magnetic flux spatial distributions with a multifractal dimension spectrum. Furthermore, we demonstrate that this magnetic spatial structure is generic, i.e., is characteristic of a very large class of random flows.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    This paper describes how the XML based RSS syndication formats used in weblogs can be utilized as the distribution medium for geo-spatial hypermedia, and how this approach can be used to create a highly distributed multi-user annotation system for geo-spatial hypermedia. It is demonstrated, how...... the HyCon annotation model [2] can be formulated as a RSS 2.0 feed and how such feeds allow annotation threads to be distributed across multiple weblogs and servers....

  15. Non-random spatial relationships between mast cells and microvessels in human endometrial carcinoma.

    Science.gov (United States)

    Guidolin, Diego; Marinaccio, Christian; Tortorella, Cinzia; Annese, Tiziana; Ruggieri, Simona; Finato, Nicoletta; Crivellato, Enrico; Ribatti, Domenico

    2017-02-01

    Mast cells (MCs) accumulate in the stroma surrounding tumors, where they secrete angiogenic cytokines and proteases, and an increased number of MCs have been demonstrated in angiogenesis associated with solid and hematological tumors. The aim of this study is to contribute to the knowledge of distribution of MCs in tumors, investigating the pattern of distribution of tryptase-positive MCs around the blood vessels in human endometrial carcinoma samples by introducing a quantitative approach to characterize their spatial distribution. The results have shown that in human endometrial cancer bioptic specimens the spatial distribution of MCs shows significant deviation from randomness as compared with control group in which, instead, the spatial distribution of MCs is consistent with a random distribution. These findings confirm that MCs enhance tumor angiogenesis and their preferential localization along blood vessels and sites of new vessel formation sustaining the suggestion for an association between MCs and angiogenesis. However, this spatial association between vessels and MCs might simply reflect migrating MCs from the blood stream at vessel growing sites.

  16. Spatially Distributed Characterization of Catchment Dynamics Using Travel-Time Distributions

    Science.gov (United States)

    Heße, F.; Zink, M.; Attinger, S.

    2015-12-01

    The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and temperature to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and therefore allow to infer

  17. Spatially Distributed Characterization of Soil Dynamics Using Travel-Time Distributions

    Science.gov (United States)

    Hesse, Falk; Zink, Matthias; Attinger, Sabine

    2016-04-01

    The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and potential evapotranspiration to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and

  18. Distributions on unbounded moment spaces and random moment sequences

    OpenAIRE

    Dette, Holger; Nagel, Jan

    2012-01-01

    In this paper we define distributions on moment spaces corresponding to measures on the real line with an unbounded support. We identify these distributions as limiting distributions of random moment vectors defined on compact moment spaces and as distributions corresponding to random spectral measures associated with the Jacobi, Laguerre and Hermite ensemble from random matrix theory. For random vectors on the unbounded moment spaces we prove a central limit theorem where the centering vecto...

  19. Probability Distributions for Random Quantum Operations

    Science.gov (United States)

    Schultz, Kevin

    Motivated by uncertainty quantification and inference of quantum information systems, in this work we draw connections between the notions of random quantum states and operations in quantum information with probability distributions commonly encountered in the field of orientation statistics. This approach identifies natural sample spaces and probability distributions upon these spaces that can be used in the analysis, simulation, and inference of quantum information systems. The theory of exponential families on Stiefel manifolds provides the appropriate generalization to the classical case. Furthermore, this viewpoint motivates a number of additional questions into the convex geometry of quantum operations relative to both the differential geometry of Stiefel manifolds as well as the information geometry of exponential families defined upon them. In particular, we draw on results from convex geometry to characterize which quantum operations can be represented as the average of a random quantum operation. This project was supported by the Intelligence Advanced Research Projects Activity via Department of Interior National Business Center Contract Number 2012-12050800010.

  20. Transforming spatial point processes into Poisson processes using random superposition

    DEFF Research Database (Denmark)

    Møller, Jesper; Berthelsen, Kasper Klitgaaard

    with a complementary spatial point process Y  to obtain a Poisson process X∪Y  with intensity function β. Underlying this is a bivariate spatial birth-death process (Xt,Yt) which converges towards the distribution of (X,Y). We study the joint distribution of X and Y, and their marginal and conditional distributions....... In particular, we introduce a fast and easy simulation procedure for Y conditional on X. This may be used for model checking: given a model for the Papangelou intensity of the original spatial point process, this model is used to generate the complementary process, and the resulting superposition is a Poisson...... process with intensity function β if and only if the true Papangelou intensity is used. Whether the superposition is actually such a Poisson process can easily be examined using well known results and fast simulation procedures for Poisson processes. We illustrate this approach to model checking...

  1. Dengue Vectors and their Spatial Distribution

    National Research Council Canada - National Science Library

    Higa, Yukiko

    2011-01-01

    .... In addition, since their life cycles are well adapted to the human environment, environmental changes resulting from human activity such as urbanization exert a great impact on vector distribution...

  2. Spatial Distribution of Cyanobacteria in Modern Stromatolites

    Science.gov (United States)

    Prufert-Bebout, Lee; Dacles-Mariani, Jennifer; Herbert, Alice; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Living stromatolites consist of complex microbial communities with distinct distribution patterns for different microbial groups. The cyanobacterial populations of Highborne Cay Bahamas exemplify this phenomenon. Field observations reveal distinct distribution patterns for several of these cyanobacterial species. To date 10 different cyanobacterial cultures, including both filamentous and endolithic species, have been isolated from these stromatolites. We will present data on the growth and motility characteristics as well as on the nutritional requirements of these isolates. These data will then be correlated with the field observed distributions for these species. Lastly laboratory simulations of stromatolites grown under various conditions of irradiance, flow and cyanobacterial community composition will be presented. These experiments allow us to evaluate our predictions regarding controls on cyanobacterial distribution.

  3. 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

  4. 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

  5. Typical features of pedestrian spatial distribution in the inflow process

    Science.gov (United States)

    Liu, Xiaodong; Song, Weiguo; Fu, Libi; Lv, Wei; Fang, Zhiming

    2016-04-01

    Pedestrian inflow is frequently observed in various pedestrian facilities. In this work, we first proposed four hypotheses concerning the inflow process. Then, we performed a series of experiments to test the hypotheses. With several analytical methods, e.g., the proxemics theory and Voronoi diagram method, the features of pedestrian inflow are analyzed in detail. Results demonstrate that the distribution of pedestrians in the room is not uniform. Boundaries are attractive for these pedestrians. The impact of two factors of the inflow are analyzed, i.e., movement rule, and first-out reward. It is found pedestrians can enter the room more effectively under the random rule or two queues. Under some hurry circumstances, pedestrians may prefer to gather around the door, and the spatial distribution is not uniform, leading to the imbalance use of the room. Practical suggestions are given for pedestrians to improve the travel efficiency in the inflow process. This experimental study is meaningful to reveal some fundamental phenomena of inflow process, which can provide the realistic basis for building the theory and mathematical-physical models.

  6. The temporal-spatial distribution of seriously maltreated children.

    Science.gov (United States)

    Thurston, Holly; Freisthler, Bridget; Bell, Janice; Tancredi, Daniel; Romano, Patrick S; Miyamoto, Sheridan; Joseph, Jill G

    2017-02-01

    This descriptive study utilized Bernoulli and Poisson spatial scan statistical models in SatScan v.9.4 to examine the distribution in space and time of residence of maltreatment cases-operationalized as families with serious maltreatment (resulting in death or hospitalization) of children under 6 years-for the presence of clusters ("hot spots"). In the Poisson model, a population dataset of serious maltreatment cases were non-randomly dispersed in four major areas, with these "hot spots" moving over time and space. Most cases were outside these clusters. In the Bernoulli model, the geographic distribution of a case-control dataset of families with serious maltreatment who were previously investigated by child welfare did not differ compared to controls previously investigated by child welfare with no serious maltreatment. Findings suggest that child fatality prevention efforts such as Back to Sleep and Never Shake a Baby campaigns should continue to be universal efforts, targeted to all parents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Inner membrane fusion mediates spatial distribution of axonal mitochondria

    Science.gov (United States)

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

    2016-01-01

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

  8. Spatial distribution of grassland productivity and land use in Europe

    NARCIS (Netherlands)

    Smit, H.J.; Metzger, M.J.; Ewert, F.

    2008-01-01

    Grasslands are an important land use in Europe with essential functions for feed and ecosystem service supply. Impact assessment modelling of European agriculture and the environment needs to consider grasslands and requires spatially explicit information on grassland distribution and productivity,

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

    African Journals Online (AJOL)

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

  10. 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)

  11. 213 SIG et distribution spatiale des infrastructures hydrauliques ...

    African Journals Online (AJOL)

    CARMELLE

    afriquescience.info. Sylvie Carmelle Gérardine HOUNGUEVOU et al. SIG et distribution spatiale des infrastructures hydrauliques dans la commune de Zè au Benin. Sylvie Carmelle GérardineHOUNGUEVOU1, Coovi Aimé BernadinTOHOZIN2*,.

  12. The Spatial Distribution of Economic Activities in Italy

    NARCIS (Netherlands)

    Dominicis, de Laura; Arbia, Giuseppe; Groot, de Henri L.F.

    2007-01-01

    Existing indices measuring the spatial distribution of economic activity such as the Krugman Specialisation Index, the Hirschmann-Herfindahl index and the Ellison-Glaeser index typically do not take into account the spatial structure of the data. In this paper, we first consider traditional measures

  13. Spatial distribution and community structure of phytoplankton ...

    African Journals Online (AJOL)

    The composition and distribution of the main planktonic halophilic microorganisms were studied in 12 ponds of different salinity levels, ranging from 38 to 328, in the saltern of Sousse, Tunisia, in relation to environmental factors. Nutrient concentrations increased with decreasing salinity in the ponds. Phytoplankton, ciliate ...

  14. Reconstructing Spatial Distributions from Anonymized Locations

    Energy Technology Data Exchange (ETDEWEB)

    Horey, James L [ORNL; Forrest, Stephanie [University of New Mexico, Albuquerque; Groat, Michael [University of New Mexico, Albuquerque

    2012-01-01

    Devices such as mobile phones, tablets, and sensors are often equipped with GPS that accurately report a person's location. Combined with wireless communication, these devices enable a wide range of new social tools and applications. These same qualities, however, leave location-aware applications vulnerable to privacy violations. This paper introduces the Negative Quad Tree, a privacy protection method for location aware applications. The method is broadly applicable to applications that use spatial density information, such as social applications that measure the popularity of social venues. The method employs a simple anonymization algorithm running on mobile devices, and a more complex reconstruction algorithm on a central server. This strategy is well suited to low-powered mobile devices. The paper analyzes the accuracy of the reconstruction method in a variety of simulated and real-world settings and demonstrates that the method is accurate enough to be used in many real-world scenarios.

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

    NARCIS (Netherlands)

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

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

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

    Indian Academy of Sciences (India)

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

  17. 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, ...

  18. 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.

  19. Perceived loudness of spatially distributed sound sources

    DEFF Research Database (Denmark)

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

    2005-01-01

    In noise-control engineering, one is often faced with the task of identifying the most problematic of several simultaneous sound sources. Traditionally, this has been done by deriving sound pressure (or intensity) maps by means of a microphone array. This approach does not, however, take...... 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...

  20. Development of Spatial Distribution Patterns by Biofilm Cells

    DEFF Research Database (Denmark)

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

    2015-01-01

    Confined spatial patterns of microbial distribution are prevalent in nature, such as in microbial mats, soil communities, and water stream biofilms. The symbiotic two-species consortium of Pseudomonas putida and Acinetobacter sp. C6, originally isolated from a creosote-polluted aquifer, has evolved...... in the context of species distribution patterns observed in macroecology, and we summarize observations about the processes involved in co-adaptation between P. putida and Acinetobacter sp. C6. Our results contribute to an understanding of spatial species distribution patterns as they are observed in nature...

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

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Gyldenkærne, Steen

    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.......-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......, 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...

  2. The effect of spatial randomness on the average fixation time of mutants

    Science.gov (United States)

    Farhang-Sardroodi, Suzan; Darooneh, Amir H.; Nikbakht, Moladad; Kohandel, Mohammad

    2017-01-01

    The mean conditional fixation time of a mutant is an important measure of stochastic population dynamics, widely studied in ecology and evolution. Here, we investigate the effect of spatial randomness on the mean conditional fixation time of mutants in a constant population of cells, N. Specifically, we assume that fitness values of wild type cells and mutants at different locations come from given probability distributions and do not change in time. We study spatial arrangements of cells on regular graphs with different degrees, from the circle to the complete graph, and vary assumptions on the fitness probability distributions. Some examples include: identical probability distributions for wild types and mutants; cases when only one of the cell types has random fitness values while the other has deterministic fitness; and cases where the mutants are advantaged or disadvantaged. Using analytical calculations and stochastic numerical simulations, we find that randomness has a strong impact on fixation time. In the case of complete graphs, randomness accelerates mutant fixation for all population sizes, and in the case of circular graphs, randomness delays mutant fixation for N larger than a threshold value (for small values of N, different behaviors are observed depending on the fitness distribution functions). These results emphasize fundamental differences in population dynamics under different assumptions on cell connectedness. They are explained by the existence of randomly occurring “dead zones” that can significantly delay fixation on networks with low connectivity; and by the existence of randomly occurring “lucky zones” that can facilitate fixation on networks of high connectivity. Results for death-birth and birth-death formulations of the Moran process, as well as for the (haploid) Wright Fisher model are presented. PMID:29176825

  3. Properties of a new small-world network with spatially biased random shortcuts

    Science.gov (United States)

    Matsuzawa, Ryo; Tanimoto, Jun; Fukuda, Eriko

    2017-11-01

    This paper introduces a small-world (SW) network with a power-law distance distribution that differs from conventional models in that it uses completely random shortcuts. By incorporating spatial constraints, we analyze the divergence of the proposed model from conventional models in terms of fundamental network properties such as clustering coefficient, average path length, and degree distribution. We find that when the spatial constraint more strongly prohibits a long shortcut, the clustering coefficient is improved and the average path length increases. We also analyze the spatial prisoner's dilemma (SPD) games played on our new SW network in order to understand its dynamical characteristics. Depending on the basis graph, i.e., whether it is a one-dimensional ring or a two-dimensional lattice, and the parameter controlling the prohibition of long-distance shortcuts, the emergent results can vastly differ.

  4. Statistical Downscaling Based on Spartan Spatial Random Fields

    Science.gov (United States)

    Hristopulos, Dionissios

    2010-05-01

    Stochastic methods of space-time interpolation and conditional simulation have been used in statistical downscaling approaches to increase the resolution of measured fields. One of the popular interpolation methods in geostatistics is kriging, also known as optimal interpolation in data assimilation. Kriging is a stochastic, linear interpolator which incorporates time/space variability by means of the variogram function. However, estimation of the variogram from data involves various assumptions and simplifications. At the same time, the high numerical complexity of kriging makes it difficult to use for very large data sets. We present a different approach based on the so-called Spartan Spatial Random Fields (SSRFs). SSRFs were motivated from classical field theories of statistical physics [1]. The SSRFs provide a different approach of parametrizing spatial dependence based on 'effective interactions,' which can be formulated based on general statistical principles or even incorporate physical constraints. This framework leads to a broad family of covariance functions [2], and it provides new perspectives in covariance parameter estimation and interpolation [3]. A significant advantage offered by SSRFs is reduced numerical complexity, which can lead to much faster codes for spatial interpolation and conditional simulation. In addition, on grids composed of rectangular cells, the SSRF representation leads to an explicit expression for the precision matrix (the inverse covariance). Therefore SSRFs could provide useful models of error covariance for data assimilation methods. We use simulated and real data to demonstrate SSRF properties and downscaled fields. keywords: interpolation, conditional simulation, precision matrix References [1] Hristopulos, D.T., 2003. Spartan Gibbs random field models for geostatistical applications, SIAM Journal in Scientific Computation, 24, 2125-2162. [2] Hristopulos, D.T., Elogne, S. N. 2007. Analytic properties and covariance

  5. DPR-tree: a distributed parallel spatial index structure for high performance spatial databases

    Science.gov (United States)

    Zhou, Yan; Zhu, Qing; Liu, Qiang

    2008-12-01

    Parallelism of spatial index could significantly improve the performance of spatial queries, special for massive spatial databases, so the research of parallel spatial index takes a important role in high performance spatial databases. Existing parallel spatial index methods have two main shortcoming: one is accessing hotspot and bottleneck of index items located in main server, the other is high costs and complicated operations for maintaining index consistency. Aim at these, a distributed parallel spatial index structure called DPR-tree is proposed. It splits whole index region into partition sub-regions by using Hilbert space-filling curve grid and organizes index sub-regions according to locality of spatial objects, then maps index sub-regions to partition sub-regions and assigns these index sub-regions to different computer nodes by a appointed map function, Each computer node manages a multi-level distributed sub-Rtree which is built from a index sub-region. Our experimental results indicate that the proposed parallel spatial index can achieve speedup well and offer significant potential for reducing query response time.

  6. Spatial Random Sampling: A Structure-Preserving Data Sketching Tool

    Science.gov (United States)

    Rahmani, Mostafa; Atia, George K.

    2017-09-01

    Random column sampling is not guaranteed to yield data sketches that preserve the underlying structures of the data and may not sample sufficiently from less-populated data clusters. Also, adaptive sampling can often provide accurate low rank approximations, yet may fall short of producing descriptive data sketches, especially when the cluster centers are linearly dependent. Motivated by that, this paper introduces a novel randomized column sampling tool dubbed Spatial Random Sampling (SRS), in which data points are sampled based on their proximity to randomly sampled points on the unit sphere. The most compelling feature of SRS is that the corresponding probability of sampling from a given data cluster is proportional to the surface area the cluster occupies on the unit sphere, independently from the size of the cluster population. Although it is fully randomized, SRS is shown to provide descriptive and balanced data representations. The proposed idea addresses a pressing need in data science and holds potential to inspire many novel approaches for analysis of big data.

  7. 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

  8. 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)

  9. A random spatial sampling method in a rural developing nation.

    Science.gov (United States)

    Kondo, Michelle C; Bream, Kent D W; Barg, Frances K; Branas, Charles C

    2014-04-10

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method using geographical information system (GIS) software and global positioning system (GPS) technology for application in a health survey in a rural region of Guatemala, as well as a qualitative study of the enumeration process. This method offers an alternative sampling technique that could reduce opportunities for bias in household selection compared to cluster methods. However, its use is subject to issues surrounding survey preparation, technological limitations and in-the-field household selection. Application of this method in remote areas will raise challenges surrounding the boundary delineation process, use and translation of satellite imagery between GIS and GPS, and household selection at each survey point in varying field conditions. This method favors household selection in denser urban areas and in new residential developments. Random spatial sampling methodology can be used to survey a random sample of population in a remote region of a developing nation. Although this method should be further validated and compared with more established methods to determine its utility in social survey applications, it shows promise for use in developing nations with resource-challenged environments where detailed geographic and human census data are less available.

  10. SPATIAL DISTRIBUTION AND SEQUENTIAL SAMPLING OF Brevipalpus phoenicis IN CITRUS

    Directory of Open Access Journals (Sweden)

    WALTER MALDONADO JR

    Full Text Available ABSTRACT Among the pests of citrus, one of the most important is the red and black flat mite Brevipalpus phoenicis (Geijskes, which transmits the Citrus leprosis virus C (CiLV-C.When a rational pest control plan is adopted, it is important to determine the correct timing for carrying out the control plan. Making this decision demands constant follow-up of the culture through periodic sampling where knowledge about the spatial distribution of the pest is a fundamental part to improve sampling and control decisions. The objective of this work was to study the spatial distribution pattern and build a sequential sampling plan for the pest. The data used were gathered from two blocks of Valencia sweet orange on a farm in São Paulo State, Brazil, by 40 inspectors trained for the data collection. The following aggregation indices were calculated: variance/ mean ratio, Morisita index, Green’s coefficient, and k parameter of the negative binomial distribution. The data were tested for fit with Poisson and negative binomial distributions using the chi-square goodness of fit test. The sequential sampling was developed using Wald’s Sequential Probability Ratio Test and validated through simulations. We concluded that the spatial distribution of B. phoenicis is aggregated, its behavior best fitted to the negative binomial distribution and we built and validated a sequential sampling plan for control decision-making.

  11. Spatial distribution of trace element of Ala river's sediments, Akure ...

    African Journals Online (AJOL)

    Spatial distribution of trace element of Ala river's sediments, Akure, Southwestern Nigeria. ... Ife Journal of Science ... Abstract. Thirty six river sediment samples were collected from Ala River, Akure, and were analysed by ICP-MS for 14 chemical elements including Cu, Pb, Zn, Ni, Co, Mn, As, U, Th, Sr, Cd, V, La, and Cr. The ...

  12. 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...

  13. Spatial and temporal distribution of cattle trypanosomosis in ...

    African Journals Online (AJOL)

    Increase in outbreaks and cases could be attributed to the inadequate resources for vector control from about the year 2002. Professional intervention and revision of current control methods and policies are therefore imperative. Keywords: African Animal Trypanosomosis, vector-borne disease, spatial - temporal distribution ...

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

    African Journals Online (AJOL)

    Spatial distribution of saline water and possible sources of intrusion into a tropical freshwater lagoon and the transitional effects on the lacustrine ichthyofaunal ... beyond the seasonal input from the two adjacent lagoons (Lagos and Mahin), salt water intrusion by subsurface flow through the barrier beach from the ocean, ...

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

    African Journals Online (AJOL)

    user

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

  16. Application of GIS-Based Spatially Distributed Hydrologic Model in ...

    African Journals Online (AJOL)

    Application of GIS-Based Spatially Distributed Hydrologic Model in Integrated Watershed Management:A Case Study of Nzoia Basin, Kenya. ... 1986 and 2000 also revealed increased peaks in resulting hydrographs as a result of increased acreage under crops and reduced forest cover for same storm characteristics.

  17. State-dependent Bayesian foraging on spatially autocorrelated food distributions

    NARCIS (Netherlands)

    Van Gils, J.A.

    2010-01-01

    When prey are cryptic and are distributed in discrete clumps (patches), Bayesian foragers revise their prior expectation about a patch's prey density by using their foraging success in the patch as a source of information. Prey densities are often spatially autocorrelated, meaning that rich patches

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

    African Journals Online (AJOL)

    It is against the background of the increasing incidence and indiscriminate springing up of informal automobile workshops in virtually every open space in Nigerian cities that this study evaluates the spatial distribution of informal automobile workshops in Osogbo. This is with a view to identifying planning strategies for ...

  19. Spatial distribution and structure of benthic macroinvertebrates in an ...

    African Journals Online (AJOL)

    Taabo Lake is facing eutrophication process characterized by a permanent and continuous colonization of its water body by invasive aquatic macrophytes since 1990. Until now, there is limited knowledge of its ecological state. The purpose of this study is to examine the spatial distribution and structure of benthic ...

  20. 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.

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

    African Journals Online (AJOL)

    Sci-Nat

    Analyse de la distribution spatiale des Acanthaceae en Afrique Centrale et comparaison avec les théories phytogéographiques de Robyns,. White et Ndjele. Kouao J. KOFFI 1*, Dominique CHAMPLUVIER 2, Danho F. R. NEUBA 3, Charles DE CANNIERE 1, Traoré DOSSAHOUA 4,. Jean LEJOLY 1, Elmar ROBBRECHT 2 ...

  2. Spatial distribution of Rhodopseudomonas palustris ecotypes on a local scale

    NARCIS (Netherlands)

    Bent, SJ; Gucker, CL; Oda, Y; Forney, LJ

    The number, spatial distribution, and significance of genetically distinguishable ecotypes of prokaryotes in the environment are poorly understood. Oda et al. (Y. Oda, B. Star, L. A. Huisman, J. C. Gottschal, and L. J. Forney, Appl. Environ. Microbiol. 69:xxx-xxx, 2003) have shown that

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

    African Journals Online (AJOL)

    The paper examined the spatial patterns of population distribution andhousing in Abraka in Delta State of Nigeria. Population is a vital componentof development in any country including Nigeria. Housing is a physical andsocial necessity of life which holds a place of strategic importance indevelopment. However, the high ...

  4. 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 ...

  5. spatial patterns of zooplankton distribution and abundance in ...

    African Journals Online (AJOL)

    nb

    §The writing of this paper was completed posthumously. ABSTRACT. Spatial patterns and ... consideration because of its changes in limnological conditions caused by nutrients inputs and ..... distribution significantly positively. Table 1: Variation of water quality parameters (mean ± standard error) measured during the study.

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

    African Journals Online (AJOL)

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  8. Spatial distribution of soluble reactive silica (SRSi) in the Tanzanian ...

    African Journals Online (AJOL)

    Spatial distribution of soluble reactive silica (SRSi) in the Tanzanian waters of Lake Victoria and its implications for diatom productivity. ... The change in diatom species composition and abundance, leading to the dominance of robust and opportunistic species, is probably accelerated by the increased eutrophication and ...

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

    African Journals Online (AJOL)

    Many coral reef fish species aggregate at specific times and locations for the purpose of spawning. This study examined the spatial and temporal distribution of spawning aggregations in the Seychelles. An interview-based survey of the principal stakeholders, mainly artisanal fishers, yielded 89 reports of aggregation fishing ...

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

    African Journals Online (AJOL)

    ACSS

    designing appropriate sampling techniques and effective Integrated Pest. Management (IPM) strategies (Chong .... under umbrella tree shade (Table 6). Discussion. Understanding spatial distribution of X. compactus ..... infestation and population dynamics before any authoritative conclusion is drawn. In our study, it is most ...

  11. Auditory spectral versus spatial temporal order judgment: Threshold distribution analysis.

    Science.gov (United States)

    Fostick, Leah; Babkoff, Harvey

    2017-05-01

    Some researchers suggested that one central mechanism is responsible for temporal order judgments (TOJ), within and across sensory channels. This suggestion is supported by findings of similar TOJ thresholds in same modality and cross-modality TOJ tasks. In the present study, we challenge this idea by analyzing and comparing the threshold distributions of the spectral and spatial TOJ tasks. In spectral TOJ, the tones differ in their frequency ("high" and "low") and are delivered either binaurally or monaurally. In spatial (or dichotic) TOJ, the two tones are identical but are presented asynchronously to the two ears and thus differ with respect to which ear received the first tone and which ear received the second tone ("left"/"left"). Although both tasks are regarded as measures of auditory temporal processing, a review of data published in the literature suggests that they trigger different patterns of response. The aim of the current study was to systematically examine spectral and spatial TOJ threshold distributions across a large number of studies. Data are based on 388 participants in 13 spectral TOJ experiments, and 222 participants in 9 spatial TOJ experiments. None of the spatial TOJ distributions deviated significantly from the Gaussian; while all of the spectral TOJ threshold distributions were skewed to the right, with more than half of the participants accurately judging temporal order at very short interstimulus intervals (ISI). The data do not support the hypothesis that 1 central mechanism is responsible for all temporal order judgments. We suggest that different perceptual strategies are employed when performing spectral TOJ than when performing spatial TOJ. We posit that the spectral TOJ paradigm may provide the opportunity for two-tone masking or temporal integration, which is sensitive to the order of the tones and thus provides perceptual cues that may be used to judge temporal order. This possibility should be considered when interpreting

  12. Effect of spatial distribution of daily rainfall on interior catchment response of a distributed hydrological model

    NARCIS (Netherlands)

    Schuurmans, J.M.; Bierkens, M.F.P.

    2006-01-01

    We investigate the effect of spatial variability of daily rainfall on soil moisture, groundwater level and discharge using a physically-based, fully-distributed hydrological model. We focus on the effect of rainfall spatial variability on day-to-day variability of the interior catchment response, as

  13. Custom-tailored spatial mode sorting by controlled random scattering

    Science.gov (United States)

    Fickler, Robert; Ginoya, Manit; Boyd, Robert W.

    2017-04-01

    The need to increase data transfer rates constitutes a key challenge in modern information-driven societies. Taking advantage of the transverse spatial modes of light to encode more information is a promising avenue for both classical and quantum photonics. However, to ease access to the encoded information, it is essential to be able to sort spatial modes into different output channels. Here, we introduce a way to customize the sorting of arbitrary spatial light modes. Our method relies on the high degree of control over random scattering processes by preshaping of the phase structure of the incident light. We demonstrate experimentally that various sets of modes, irrespective of their specific modal structure, can be transformed to a broad range of output channel arrangements. Thus, our method enables full access to all of the information encoded in the transverse structure of the field; for example, azimuthal and radial modes. We also demonstrate that coherence is retained in this complex mode transformation, which opens up applications in quantum and classical information science.

  14. Spatial distribution of angular momentum inside the nucleon

    Science.gov (United States)

    Lorcé, Cédric; Mantovani, Luca; Pasquini, Barbara

    2018-01-01

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

  15. Convolutional neural networks for estimating spatially distributed evapotranspiration

    Science.gov (United States)

    García-Pedrero, Angel M.; Gonzalo-Martín, Consuelo; Lillo-Saavedra, Mario F.; Rodriguéz-Esparragón, Dionisio; Menasalvas, Ernestina

    2017-10-01

    Efficient water management in agriculture requires an accurate estimation of evapotranspiration (ET). There are available several balance energy surface models that provide a daily ET estimation (ETd) spatially and temporarily distributed for different crops over wide areas. These models need infrared thermal spectral band (gathered from remotely sensors) to estimate sensible heat flux from the surface temperature. However, this spectral band is not available for most current operational remote sensors. Even though the good results provided by machine learning (ML) methods in many different areas, few works have applied these approaches for forecasting distributed ETd on space and time when aforementioned information is missing. However, these methods do not exploit the land surface characteristics and the relationships among land covers producing estimation errors. In this work, we have developed and evaluated a methodology that provides spatial distributed estimates of ETd without thermal information by means of Convolutional Neural Networks.

  16. Spatial Distribution of Gamma-Ray Burst Sources

    Science.gov (United States)

    Shirokov, S. I.; Raikov, A. A.; Baryshev, Yu. V.

    2017-12-01

    The spatial distribution of sources of gamma-ray bursts (GRB) with known red shifts is analyzed by the conditional density and pairwise distance methods. The sample of GRB is based on data from the Swift program and contains fluxes, coordinates, and red shifts for 384 GRB sources. Selection effects that distort the true source distribution are taken into account by comparing the observed distribution with fractal and uniform model catalogs. The Malmqvist effect is modeled using an approximation for the visible luminosity function of the GRB. The case of absorption in the galactic plane is also examined. This approach makes it possible to study the spatial structure of the entire sample at one time without artificial truncations. The estimated fractal dimensionality is D = 2.55 ± 0.06 on scales of 2-6 Gpc.

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

    Science.gov (United States)

    Vögeli, Christian; Lehning, Michael; Wever, Nander; Bavay, Mathias

    2016-12-01

    Accurate knowledge on snow distribution in alpine terrain is crucial for various applications such 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 interpolations of observations from automatic weather stations (AWS), leading to errors in the spatial distribution of atmospheric forcing. With recent advances in remote sensing techniques, maps of snow depth can be acquired with high spatial resolution and accuracy. In this work, maps of the snow depth distribution, calculated from summer and winter digital surface models based on Airborne Digital Sensors (ADS), are used to scale precipitation input data, with the aim to improve the accuracy of simulation of the spatial distribution of snow with Alpine3D. A simple method to scale and redistribute precipitation is presented and the performance is analysed. The scaling method 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 for the simulated domain. The standard deviation of absolute snow depth error is reduced up to a factor 3.4 to less than 20 cm. The mean absolute error in snow distribution was reduced when using representative input sources for the simulation domain. For inter-annual scaling, the model performance could also be improved, even when using a remote sensing dataset from a different winter. In conclusion, using remote sensing data to process precipitation input, complex processes 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. Uncertainty in Random Forests: What does it mean in a spatial context?

    Science.gov (United States)

    Klump, Jens; Fouedjio, Francky

    2017-04-01

    Geochemical surveys are an important part of exploration for mineral resources and in environmental studies. The samples and chemical analyses are often laborious and difficult to obtain and therefore come at a high cost. As a consequence, these surveys are characterised by datasets with large numbers of variables but relatively few data points when compared to conventional big data problems. With more remote sensing platforms and sensor networks being deployed, large volumes of auxiliary data of the surveyed areas are becoming available. The use of these auxiliary data has the potential to improve the prediction of chemical element concentrations over the whole study area. Kriging is a well established geostatistical method for the prediction of spatial data but requires significant pre-processing and makes some basic assumptions about the underlying distribution of the data. Some machine learning algorithms, on the other hand, may require less data pre-processing and are non-parametric. In this study we used a dataset provided by Kirkwood et al. [1] to explore the potential use of Random Forest in geochemical mapping. We chose Random Forest because it is a well understood machine learning method and has the advantage that it provides us with a measure of uncertainty. By comparing Random Forest to Kriging we found that both methods produced comparable maps of estimated values for our variables of interest. Kriging outperformed Random Forest for variables of interest with relatively strong spatial correlation. The measure of uncertainty provided by Random Forest seems to be quite different to the measure of uncertainty provided by Kriging. In particular, the lack of spatial context can give misleading results in areas without ground truth data. In conclusion, our preliminary results show that the model driven approach in geostatistics gives us more reliable estimates for our target variables than Random Forest for variables with relatively strong spatial

  19. A fast high-spatial-resolution Raman distributed temperature sensor

    Science.gov (United States)

    Chen, Y.; Hartog, A. H.; Marsh, R. J.; Hilton, I. M.; Hadley, M. R.; Ross, P. A.

    2014-05-01

    Conventional high-spatial-resolution Raman distributed temperature sensing (DTS) systems are based on photoncounting techniques, which result in slow measurements over short sensing fibers. We describe an alternative approach that uses a high-power, short-pulse-width laser and provides fast measurements over fibers longer than 1 km. We demonstrate measurements with 1-s update times over fiber lengths greater than 1 km with better than 0.4-m spatial resolution. We introduce a figure of merit for DTS and we show a substantial improvement (x 100) over earlier results.

  20. 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.

  1. 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.

  2. 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...

  3. Testing in a Random Effects Panel Data Model with Spatially Correlated Error Components and Spatially Lagged Dependent Variables

    Directory of Open Access Journals (Sweden)

    Ming He

    2015-11-01

    Full Text Available We propose a random effects panel data model with both spatially correlated error components and spatially lagged dependent variables. We focus on diagnostic testing procedures and derive Lagrange multiplier (LM test statistics for a variety of hypotheses within this model. We first construct the joint LM test for both the individual random effects and the two spatial effects (spatial error correlation and spatial lag dependence. We then provide LM tests for the individual random effects and for the two spatial effects separately. In addition, in order to guard against local model misspecification, we derive locally adjusted (robust LM tests based on the Bera and Yoon principle (Bera and Yoon, 1993. We conduct a small Monte Carlo simulation to show the good finite sample performances of these LM test statistics and revisit the cigarette demand example in Baltagi and Levin (1992 to illustrate our testing procedures.

  4. Spatial and temporal distribution of snowmelt rate in Japan

    Science.gov (United States)

    Sen Gupta, A.; Chowdhary, H.; Chinnayakanahalli, K.; Ashouri, H.

    2016-12-01

    Volume and timing of runoff due to snowmelt are major factors influencing the magnitude and timing of floods, reservoir operations, as well as the duration of the skiing season in the high-altitude northern regions of Japan. Snowmelt models are often used within rainfall-runoff models to estimate snowmelt runoff. In order to accurately model snowmelt runoff, these models need to account for the spatial and temporal variability of the snowmelt rate. Temperature index (TI) snowmelt models are commonly used for this purpose owing to their simplicity, parsimonious nature and computational efficiency. Traditional TI models assume a constant melt rate or degree day factor (DDF) over the entire melting season which usually overestimates the melt quantity during early season and underestimates during the latter part of the season. Moreover, available information on the spatial variability of the DDF is generally inadequate to develop spatially distributed snowmelt models. In this study, DDF has been estimated using Global Land Data Assimilation System (GLDAS) Noah Land Surface Model (LSM) outputs over Japan at 0.25° spatial resolution. 3-hourly temperature and snowmelt amount data have been used to estimate spatially varying daily melt rates resulting in time-varying seasonal melt factor curve similar to that proposed in SNOW-17. A distributed TI model was then applied to model snow water equivalent (SWE) and daily snowmelt over the entire Japan from 2000 to 2010. The modeled distributions of the onset and cessation of the snowpack buildup, and of the annual maximum SWE and its time of occurrence have been found to be in agreement with the patterns available from the GLDAS Noah data. The model performed better for Hokkaido, the northernmost of Japan's five main islands, where the annual maximum SWE is higher compared to the other parts of the country. The DDFs estimated in this study provide improved snowmelt driven flood estimates, especially for northern Japan.

  5. Soil nutrients influence spatial distributions of tropical tree species.

    Science.gov (United States)

    John, Robert; Dalling, James W; Harms, Kyle E; Yavitt, Joseph B; Stallard, Robert F; Mirabello, Matthew; Hubbell, Stephen P; Valencia, Renato; Navarrete, Hugo; Vallejo, Martha; Foster, Robin B

    2007-01-16

    The importance of niche vs. neutral assembly mechanisms in structuring tropical tree communities remains an important unsettled question in community ecology [Bell G (2005) Ecology 86:1757-1770]. There is ample evidence that species distributions are determined by soils and habitat factors at landscape (Yasuni), and Panama (Barro Colorado Island). Using spatial distribution maps of >0.5 million individual trees of 1,400 species and 10 essential plant nutrients, we used Monte Carlo simulations of species distributions to test plant-soil associations against null expectations based on dispersal assembly. We found that the spatial distributions of 36-51% of tree species at these sites show strong associations to soil nutrient distributions. Neutral dispersal assembly cannot account for these plant-soil associations or the observed niche breadths of these species. These results indicate that belowground resource availability plays an important role in the assembly of tropical tree communities at local scales and provide the basis for future investigations on the mechanisms of resource competition among tropical tree species.

  6. Spatially distributed lateral nitrate transport at the catchment scale.

    Science.gov (United States)

    Hesser, Fred B; Franko, Uwe; Rode, Michael

    2010-01-01

    In river catchments, N transformation and storage processes during lateral transport are important in controlling N loads of surface waters. There is a lack of approaches which capture lateral flows and associated N transformation in a spatially distributed way. The aim of this paper is to develop a new conceptual N transport and transformation model which simulates the lateral nitrate transport in subsurface flow from the source area to the receiving water body. The developed tool is based on the object modeling system (OMS) framework and consists of the analytical spatially distributed hydrological model J2000, the nitrate recharge model Meta Candy and a new groundwater N routing component. Nitrate degradation in groundwater is calculated stoichiometrically according to a predefined amount on oxidizable substrate. The new modeling approach was tested in a small agricultural lower mountain range catchment of Thuringia, Germany. The calibration of the N model using a 4-yr period showed reasonable results for nitrate load calculations with a Nash and Sutcliff coefficient of 0.78. The 3-yr validation period produced Nash-Sutcliff (NS) values of 0.75. There was a clear relationship of the goodness-of-fit between the hydrological simulations and the nitrate concentration calculations. Due to short residence times of the interflow nitrate degradation was restricted to slow base flow components. The new approach can be used to target N source areas within a catchment and assess the impact of these source areas on the N load of surface waters in a spatially distributed manner.

  7. On bounds in Poisson approximation for distributions of independent negative-binomial distributed random variables.

    Science.gov (United States)

    Hung, Tran Loc; Giang, Le Truong

    2016-01-01

    Using the Stein-Chen method some upper bounds in Poisson approximation for distributions of row-wise triangular arrays of independent negative-binomial distributed random variables are established in this note.

  8. Hybrid computer technique yields random signal probability distributions

    Science.gov (United States)

    Cameron, W. D.

    1965-01-01

    Hybrid computer determines the probability distributions of instantaneous and peak amplitudes of random signals. This combined digital and analog computer system reduces the errors and delays of manual data analysis.

  9. Randomized distributed access to mutually exclusive resources

    Directory of Open Access Journals (Sweden)

    Moshe Dror

    2005-01-01

    they generally suffer from the need for extensive interagent communication. In this paper, we develop a randomized approach to make multiagent resource-allocation decisions with the objective of maximizing expected concurrency measured by the number of the active agents. This approach does not assume a centralized mechanism and has no need for interagent communication. Compared to existing autonomous-decentralized-decision-making (ADDM-based approaches for resource-allocation, our work emphasizes achieving the highest degree of agent autonomy and is able to handle more general resource requirements.

  10. 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.

  11. Characterizations of Distributions of Ratios of Certain Independent Random Variables

    Directory of Open Access Journals (Sweden)

    Hamedani G.G.

    2013-05-01

    Full Text Available Various characterizations of the distributions of the ratio of two independent gamma and exponential random variables as well as that of two independent Weibull random variables are presented. These characterizations are based, on a simple relationship between two truncated moments ; on hazard function ; and on functions of order statistics.

  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. Spatial variability of Chinook salmon spawning distribution and habitat preferences

    Science.gov (United States)

    Cram, Jeremy M.; Torgersen, Christian; Klett, Ryan S.; Pess, George R.; May, Darran; Pearsons, Todd N.; Dittman, Andrew H.

    2017-01-01

    We investigated physical habitat conditions associated with the spawning sites of Chinook Salmon Oncorhynchus tshawytscha and the interannual consistency of spawning distribution across multiple spatial scales using a combination of spatially continuous and discrete sampling methods. We conducted a census of aquatic habitat in 76 km of the upper main-stem Yakima River in Washington and evaluated spawning site distribution using redd survey data from 2004 to 2008. Interannual reoccupation of spawning areas was high, ranging from an average Pearson’s correlation of 0.62 to 0.98 in channel subunits and 10-km reaches, respectively. Annual variance in the interannual correlation of spawning distribution was highest in channel units and subunits, but it was low at reach scales. In 13 of 15 models developed for individual years (2004–2008) and reach lengths (800 m, 3 km, 6 km), stream power and depth were the primary predictors of redd abundance. Multiple channels and overhead cover were patchy but were important secondary and tertiary predictors of reach-scale spawning site selection. Within channel units and subunits, pool tails and thermal variability, which may be associated with hyporheic exchange, were important predictors of spawning. We identified spawning habitat preferences within reaches and channel units that are relevant for salmonid habitat restoration planning. We also identified a threshold (i.e., 2-km reaches) beyond which interannual spawning distribution was markedly consistent, which may be informative for prioritizing habitat restoration or conservation. Management actions may be improved through enhanced understanding of spawning habitat preferences and the consistency with which Chinook Salmon reoccupy spawning areas at different spatial scales.

  14. Towards Bayesian Inference of the Spatial Distribution of Proteins

    DEFF Research Database (Denmark)

    Hooghoudt, Jan Otto; Waagepetersen, Rasmus Plenge; Barroso, Margarida

    2017-01-01

    Főrster resonance energy transfer (FRET) is a quantum-physical phenomenon where energy may be transferred from one molecule to a neighbour molecule if the molecules are close enough. Using fluorophore molecule marking of proteins in a cell it is possible to measure in microscopic images to what...... extent FRET takes place between the fluorophores. This provides indirect information of the spatial distribution of the proteins. Questions of particular interest are whether (and if so to which extent) proteins of possibly different types interact or whether they appear independently of each other....... In this paper we propose a new likelihood-based approach to statistical inference for FRET microscopic data. The likelihood function is obtained from a detailed modeling of the FRET data generating mechanism conditional on a protein configuration. We next follow a Bayesian approach and introduce a spatial point...

  15. On Distributed Computation in Noisy Random Planar Networks

    OpenAIRE

    Kanoria, Y.; Manjunath, D.

    2007-01-01

    We consider distributed computation of functions of distributed data in random planar networks with noisy wireless links. We present a new algorithm for computation of the maximum value which is order optimal in the number of transmissions and computation time.We also adapt the histogram computation algorithm of Ying et al to make the histogram computation time optimal.

  16. Asymptotic distribution of products of sums of independent random ...

    Indian Academy of Sciences (India)

    453007 Henan, China. E-mail: bigduckwyl@163.com; duhongxia24@gmail.com. MS received 7 April 2012; revised 10 October 2012. Abstract. In the paper we consider the asymptotic distribution of products of weighted sums of independent random variables. Keywords. Asymptotic distribution; products of sums. 1.

  17. Spatial distribution of environmental DNA in a nearshore marine habitat.

    Science.gov (United States)

    O'Donnell, James L; Kelly, Ryan P; Shelton, Andrew Olaf; Samhouri, Jameal F; Lowell, Natalie C; Williams, Gregory D

    2017-01-01

    In the face of increasing threats to biodiversity, the advancement of methods for surveying biological communities is a major priority for ecologists. Recent advances in molecular biological technologies have made it possible to detect and sequence DNA from environmental samples (environmental DNA or eDNA); however, eDNA techniques have not yet seen widespread adoption as a routine method for biological surveillance primarily due to gaps in our understanding of the dynamics of eDNA in space and time. In order to identify the effective spatial scale of this approach in a dynamic marine environment, we collected marine surface water samples from transects ranging from the intertidal zone to four kilometers from shore. Using PCR primers that target a diverse assemblage of metazoans, we amplified a region of mitochondrial 16S rDNA from the samples and sequenced the products on an Illumina platform in order to detect communities and quantify their spatial patterns using a variety of statistical tools. We find evidence for multiple, discrete eDNA communities in this habitat, and show that these communities decrease in similarity as they become further apart. Offshore communities tend to be richer but less even than those inshore, though diversity was not spatially autocorrelated. Taxon-specific relative abundance coincided with our expectations of spatial distribution in taxa lacking a microscopic, pelagic life-history stage, though most of the taxa detected do not meet these criteria. Finally, we use carefully replicated laboratory procedures to show that laboratory treatments were remarkably similar in most cases, while allowing us to detect a faulty replicate, emphasizing the importance of replication to metabarcoding studies. While there is much work to be done before eDNA techniques can be confidently deployed as a standard method for ecological monitoring, this study serves as a first analysis of diversity at the fine spatial scales relevant to marine ecologists

  18. Spatial distribution of environmental DNA in a nearshore marine habitat

    Directory of Open Access Journals (Sweden)

    James L. O’Donnell

    2017-02-01

    Full Text Available In the face of increasing threats to biodiversity, the advancement of methods for surveying biological communities is a major priority for ecologists. Recent advances in molecular biological technologies have made it possible to detect and sequence DNA from environmental samples (environmental DNA or eDNA; however, eDNA techniques have not yet seen widespread adoption as a routine method for biological surveillance primarily due to gaps in our understanding of the dynamics of eDNA in space and time. In order to identify the effective spatial scale of this approach in a dynamic marine environment, we collected marine surface water samples from transects ranging from the intertidal zone to four kilometers from shore. Using PCR primers that target a diverse assemblage of metazoans, we amplified a region of mitochondrial 16S rDNA from the samples and sequenced the products on an Illumina platform in order to detect communities and quantify their spatial patterns using a variety of statistical tools. We find evidence for multiple, discrete eDNA communities in this habitat, and show that these communities decrease in similarity as they become further apart. Offshore communities tend to be richer but less even than those inshore, though diversity was not spatially autocorrelated. Taxon-specific relative abundance coincided with our expectations of spatial distribution in taxa lacking a microscopic, pelagic life-history stage, though most of the taxa detected do not meet these criteria. Finally, we use carefully replicated laboratory procedures to show that laboratory treatments were remarkably similar in most cases, while allowing us to detect a faulty replicate, emphasizing the importance of replication to metabarcoding studies. While there is much work to be done before eDNA techniques can be confidently deployed as a standard method for ecological monitoring, this study serves as a first analysis of diversity at the fine spatial scales relevant to

  19. 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.

  20. 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.

  1. The generation of spatial population distributions from census centroid data.

    Science.gov (United States)

    Bracken, I; Martin, D

    1989-04-01

    "Census data are commonly used in geographical analysis and to inform planning purposes, though at the disaggregate level the basis of enumeration poses difficulties. In this paper an approach to surface generation is described that offers the prospect of revealing an underlying population distribution from centroid-based data which is independent of zonal geography. It is suggested that this can serve a wide variety of analytical, cartographic, and policy purposes, including the creation of spatial indicators of economic and social conditions and enhancing the value of census data. The approach is illustrated by reference to an analysis of part of the valleys of South Wales, in the United Kingdom." excerpt

  2. Continuous Time Random Walks with memory and financial distributions

    Science.gov (United States)

    Montero, Miquel; Masoliver, Jaume

    2017-11-01

    We study financial distributions from the perspective of Continuous Time Random Walks with memory. We review some of our previous developments and apply them to financial problems. We also present some new models with memory that can be useful in characterizing tendency effects which are inherent in most markets. We also briefly study the effect on return distributions of fractional behaviors in the distribution of pausing times between successive transactions.

  3. Fully-distributed randomized cooperation in wireless sensor networks

    KAUST Repository

    Bader, Ahmed

    2015-01-07

    When marrying randomized distributed space-time coding (RDSTC) to geographical routing, new performance horizons can be created. In order to reach those horizons however, routing protocols must evolve to operate in a fully distributed fashion. In this letter, we expose a technique to construct a fully distributed geographical routing scheme in conjunction with RDSTC. We then demonstrate the performance gains of this novel scheme by comparing it to one of the prominent classical schemes.

  4. Sex ratio and spatial distribution of male and female Antennaria dioica (Asteraceae) plants

    Science.gov (United States)

    Varga, Sandra; Kytöviita, Minna-Maarit

    2011-09-01

    Sex ratio, sex spatial distribution and sexual dimorphism in reproduction and arbuscular mycorrhizal colonisation were investigated in the dioecious clonal plant Antennaria dioica (Asteraceae). Plants were monitored for five consecutive years in six study plots in Oulanka, northern Finland. Sex ratio, spatial distribution of sexes, flowering frequency, number of floral shoots and the number and weight of inflorescences were recorded. In addition, intensity of mycorrhizal fungi in the roots was assessed. Both sexes flowered each year with a similar frequency, but the overall genet sex ratio was strongly female-biased. The bivariate Ripley's analysis of the sex distribution showed that within most plots sexes were randomly distributed except for one plot. Sexual dimorphism was expressed as larger floral and inflorescence production and heavier inflorescences in males. In addition, the roots of both sexes were colonised to a similar extent by arbuscular mycorrhizal fungi. The female sex-biased flowering ratios reported are not consistent among years and cannot be explained in terms of spatial segregation of the sexes or sex lability. The possible reasons for the female-biased sex ratio are discussed.

  5. Evaluation and mapping spatial distribution of bottom sediment heavy metal contamination in Burullus Lake, Egypt

    Directory of Open Access Journals (Sweden)

    Yasser A. El-Amier

    2017-03-01

    Full Text Available Burullus Lake is one of most important lakes in north Delta of Egypt. It is exposed to huge amounts of serious pollutants especially heavy metals. The sediments within the lake aid in the dispersion of these metals. The main objectives of this research were to evaluate and map the spatial distribution of heavy metals in Burullus Lake sediments. Accordingly, 37 locations were randomly distributed within the lake. Sediment samples were taken from these locations. These samples were analyzed for seven metals including Fe, Cu, Zn, Cr, Co, Cd and Pb. Also, five indices were used to identify the status of metal pollutants in the Lake. These indices are: enrichment factor (EF, contamination factor (CF, degree of contamination (DC, pollution load index (PLI and geo-accumulation index (Igeo. Ordinary Kriging was used to interpolate the spatial distribution of the studied elements within the lake. The obtained results indicated that cadmium was the most enriched element in the lake sediments due to industrial and agricultural wastes drained into the lake. The Igeo index revealed that Cd and Pb were the common pollutants in lake sediments. The DC values ranged between low (near El-Boughaz and moderate (near drainage areas. The spatial distribution of pollutants within the lake indicated that the highly polluted areas are located close to the drains, whereas as the less polluted areas were close to El-Boughaz.

  6. The Temporal and Spatial Distribution of Filbert Weevil Infested Acorns in an Oak Woodland in Marin County, California

    Science.gov (United States)

    Vernard R. Lewis

    1991-01-01

    Two-hundred shoots contained within randomly selected locations from each of thirty-six coast live oak, Quercus agrifolia, trees were sampled to determine the abundance and spatial distribution of acorns infested by the filbert weevil, Curculio occidentis in northern California during 1989. The seasonal abundance of infested acorns...

  7. Effect of permethrin-treated bed nets on the spatial distribution of malaria vectors in western Kenya

    NARCIS (Netherlands)

    Gimnig, John E.; Kolczak, Margarette S.; Hightower, Allen W.; Vulule, John M.; Schoute, Erik; Kamau, Luna; Phillips-Howard, Penelope A.; ter Kuile, Feiko O.; Nahlen, Bernard L.; Hawley, William A.

    2003-01-01

    The effect of insecticide (permethrin)-treated bed nets (ITNs) on the spatial distribution of malaria vectors in neighboring villages lacking ITNs was studied during a randomized controlled trial of ITNs in western Kenya. There was a trend of decreased abundance of Anopheles gambiae with decreasing

  8. Monofractal or multifractal: a case study of spatial distribution of mining-induced seismic activity

    Directory of Open Access Journals (Sweden)

    M. Eneva

    1994-01-01

    Full Text Available Using finite data sets and limited size of study volumes may result in significant spurious effects when estimating the scaling properties of various physical processes. These effects are examined with an example featuring the spatial distribution of induced seismic activity in Creighton Mine (northern Ontario, Canada. The events studied in the present work occurred during a three-month period, March-May 1992, within a volume of approximate size 400 x 400 x 180 m3. Two sets of microearthquake locations are studied: Data Set 1 (14,338 events and Data Set 2 (1654 events. Data Set 1 includes the more accurately located events and amounts to about 30 per cent of all recorded data. Data Set 2 represents a portion of the first data set that is formed by the most accurately located and the strongest microearthquakes. The spatial distribution of events in the two data sets is examined for scaling behaviour using the method of generalized correlation integrals featuring various moments q. From these, generalized correlation dimensions are estimated using the slope method. Similar estimates are made for randomly generated point sets using the same numbers of events and the same study volumes as for the real data. Uniform and monofractal random distributions are used for these simulations. In addition, samples from the real data are randomly extracted and the dimension spectra for these are examined as well. The spectra for the uniform and monofractal random generations show spurious multifractality due only to the use of finite numbers of data points and limited size of study volume. Comparing these with the spectra of dimensions for Data Set 1 and Data Set 2 allows us to estimate the bias likely to be present in the estimates for the real data. The strong multifractality suggested by the spectrum for Data Set 2 appears to be largely spurious; the spatial distribution, while different from uniform, could originate from a monofractal process. The spatial

  9. Thoron, radon and air ions spatial distribution in indoor air.

    Science.gov (United States)

    Kolarž, Predrag; Vaupotič, Janja; Kobal, Ivan; Ujić, Predrag; Stojanovska, Zdenka; Žunić, Zora S

    2017-07-01

    Spatial distribution of radioactive gasses thoron (Tn) and radon (Rn) in indoor air of 9 houses mostly during winter period of 2013 has been studied. According to properties of alpha decay of both elements, air ionization was also measured. Simultaneous continual measurements using three Rn/Tn and three air-ion active instruments deployed on to three different distances from the wall surface have shown various outcomes. It has turned out that Tn and air ions concentrations decrease with the distance increase, while Rn remained uniformly distributed. Exponential fittings function for Tn variation with distance was used for the diffusion length and constant as well as the exhalation rate determination. The obtained values were similar with experimental data reported in the literature. Concentrations of air ions were found to be in relation with Rn and obvious, but to a lesser extent, with Tn. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Spatial Distribution Balance Analysis of Hospitals in Wuhan.

    Science.gov (United States)

    Yang, Nai; Chen, Shiyi; Hu, Weilu; Wu, Zhongheng; Chao, Yi

    2016-09-30

    The spatial distribution pattern of hospitals in Wuhan indicates a core in the central urban areas and a sparse distribution in the suburbs, particularly at the center of suburbs. This study aims to improve the gravity and Huff models to analyze healthcare accessibility and resources. Results indicate that healthcare accessibility in central urban areas is better than in the suburbs, where it increasingly worsens for the suburbs. A shortage of healthcare resources is observed in large-scale and high-class hospitals in central urban areas, whereas the resources of some hospitals in the suburbs are redundant. This study proposes the multi-criteria evaluation (MCE) analysis model for the location assessment in constructing new hospitals, which can effectively ameliorate healthcare accessibility in suburban areas. This study presents implications for the planning of urban healthcare facilities.

  11. Mosquito-producing containers, spatial distribution, and relationship between Aedes aegypti population indices on the southern boundary of its distribution in South America (Salto, Uruguay).

    Science.gov (United States)

    Basso, César; Caffera, Ruben M; García da Rosa, Elsa; Lairihoy, Rosario; González, Cristina; Norbis, Walter; Roche, Ingrid

    2012-12-01

    A study was conducted in the city of Salto, Uruguay, to identify mosquito-producing containers, the spatial distribution of mosquitoes and the relationship between the different population indices of Aedes aegypti. On each of 312 premises visited, water-filled containers and immature Ae. aegypti mosquitoes were identified. The containers were counted and classified into six categories. Pupae per person and Stegomyia indices were calculated. Pupae per person were represented spatially. The number of each type of container and number of mosquitoes in each were analyzed and compared, and their spatial distribution was analyzed. No significant differences in the number of the different types of containers with mosquitoes or in the number of mosquitoes in each were found. The distribution of the containers with mosquito was random and the distribution of mosquitoes by type of container was aggregated or highly aggregated.

  12. Mosquito-Producing Containers, Spatial Distribution, and Relationship between Aedes aegypti Population Indices on the Southern Boundary of its Distribution in South America (Salto, Uruguay)

    Science.gov (United States)

    Basso, César; Caffera, Ruben M.; García da Rosa, Elsa; Lairihoy, Rosario; González, Cristina; Norbis, Walter; Roche, Ingrid

    2012-01-01

    A study was conducted in the city of Salto, Uruguay, to identify mosquito-producing containers, the spatial distribution of mosquitoes and the relationship between the different population indices of Aedes aegypti. On each of 312 premises visited, water-filled containers and immature Ae. aegypti mosquitoes were identified. The containers were counted and classified into six categories. Pupae per person and Stegomyia indices were calculated. Pupae per person were represented spatially. The number of each type of container and number of mosquitoes in each were analyzed and compared, and their spatial distribution was analyzed. No significant differences in the number of the different types of containers with mosquitoes or in the number of mosquitoes in each were found. The distribution of the containers with mosquito was random and the distribution of mosquitoes by type of container was aggregated or highly aggregated. PMID:23128295

  13. 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.

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

    Science.gov (United States)

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

    2013-01-01

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

  15. [Population structure and spatial distribution pattern of Camellia azalea in E' huangzhang Nature Reserve of Guangdong, China].

    Science.gov (United States)

    Li, Xin-lei; Sun, Zhen-yuan; Li, Ji-yuan; Xu, Yi; Luo, Jian

    2013-08-01

    This paper studied the structures of basal diameter, height and canopy width of Camellia azalea population in E' huangzhang Nature Reserve of Guangdong. The spatial distribution patterns and dynamics of the population were measured by applying aggregate indices including disperse coefficient, negative binomial distribution, Cassie index, clumping index, mean crowding, patch index and Green index. The results showed that in the natural distribution region, the population was mainly composed of adult trees, and was in declining due to seriously lack of seedlings. The structures of diameter, height and canopy width were not identical among different plots. In the plots, the spatial distribution pattern of C. azalea population showed clump or random, and changed from clump to random with the development of the population.

  16. 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

  17. 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.

  18. 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.

  19. Environmental DNA reflects spatial and temporal jellyfish distribution.

    Science.gov (United States)

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

    2017-01-01

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

  20. Determination of the Spatial Distribution in Hydraulic Conductivity Using Genetic Algorithm Optimization

    Science.gov (United States)

    Aksoy, A.; Lee, J. H.; Kitanidis, P. K.

    2016-12-01

    Heterogeneity in hydraulic conductivity (K) impacts the transport and fate of contaminants in subsurface as well as design and operation of managed aquifer recharge (MAR) systems. Recently, improvements in computational resources and availability of big data through electrical resistivity tomography (ERT) and remote sensing have provided opportunities to better characterize the subsurface. Yet, there is need to improve prediction and evaluation methods in order to obtain information from field measurements for better field characterization. In this study, genetic algorithm optimization, which has been widely used in optimal aquifer remediation designs, was used to determine the spatial distribution of K. A hypothetical 2 km by 2 km aquifer was considered. A genetic algorithm library, PGAPack, was linked with a fast Fourier transform based random field generator as well as a groundwater flow and contaminant transport simulation model (BIO2D-KE). The objective of the optimization model was to minimize the total squared error between measured and predicted field values. It was assumed measured K values were available through ERT. Performance of genetic algorithm in predicting the distribution of K was tested for different cases. In the first one, it was assumed that observed K values were evaluated using the random field generator only as the forward model. In the second case, as well as K-values obtained through ERT, measured head values were incorporated into evaluation in which BIO2D-KE and random field generator were used as the forward models. Lastly, tracer concentrations were used as additional information in the optimization model. Initial results indicated enhanced performance when random field generator and BIO2D-KE are used in combination in predicting the spatial distribution in K.

  1. On the Marginal Distribution of the Diagonal Blocks in a Blocked Wishart Random Matrix

    Directory of Open Access Journals (Sweden)

    Kjetil B. Halvorsen

    2016-01-01

    Full Text Available Let A be a (m1+m2×(m1+m2 blocked Wishart random matrix with diagonal blocks of orders m1×m1 and m2×m2. The goal of the paper is to find the exact marginal distribution of the two diagonal blocks of A. We find an expression for this marginal density involving the matrix-variate generalized hypergeometric function. We became interested in this problem because of an application in spatial interpolation of random fields of positive definite matrices, where this result will be used for parameter estimation, using composite likelihood methods.

  2. 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

  3. Maximum Likelihood and Bayes Estimation in Randomly Censored Geometric Distribution

    Directory of Open Access Journals (Sweden)

    Hare Krishna

    2017-01-01

    Full Text Available In this article, we study the geometric distribution under randomly censored data. Maximum likelihood estimators and confidence intervals based on Fisher information matrix are derived for the unknown parameters with randomly censored data. Bayes estimators are also developed using beta priors under generalized entropy and LINEX loss functions. Also, Bayesian credible and highest posterior density (HPD credible intervals are obtained for the parameters. Expected time on test and reliability characteristics are also analyzed in this article. To compare various estimates developed in the article, a Monte Carlo simulation study is carried out. Finally, for illustration purpose, a randomly censored real data set is discussed.

  4. Spatial distribution of metals in the constructed wetlands.

    Science.gov (United States)

    Kongroy, Porntawee; Tantemsapya, Netnapid; Lin, Ying-Feng; Jing, Shuh Ren; Wirojanagud, Wanpen

    2012-02-01

    Investigation of the spatial distribution of metals was conducted for two constructed wetlands used as tertiary treatment in Chia Nan University of Pharmacy and Science (CNU) and Metal Processing Industries (MPI) located in Tainan, Taiwan. These two distinguished sites were selected to compare the distribution of metals for constructed wetlands treating different types of wastewater. Along the distance, samples of water, sediment, and macrophytes were analyzed for metals including Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Additionally, measurements of water quality including temperature, pH, EC, ORP, DO, TSS, BOD, COD, and turbidity were performed. Results show that, at CNU, wastewater contained higher organic consititute (BOD 29.3 +/- 11.7 mg/, COD 46.7 +/- 33.6 mg/L) with low metals content. Wastewater at MPI contained low level of organic consititute (BOD 7.1 +/- 3.3 mg/L, and COD 66.0 +/- 56.5 mg/L) and higher metals content. Metals distribution of both sites showed similar results where metals in the sediments in the inlet zone have greater concentrations than other areas. The constructed wetlands can remove Cd, Cu, Ni, Pb, and Zn. However, there was no removal of Al, Cr, Fe, and Mn. A distance along the constructed wetlands had no effect on metal concentrations in macrophyte and water.

  5. 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.

  6. Spatial data integration from distributed and heterogeneous sources

    Directory of Open Access Journals (Sweden)

    Genoveva Vargas S.

    2004-01-01

    Full Text Available El presente trabajo discute los retos asociados a la integración de datos espaciales y presenta el enfoque adoptado en el proyecto SPIDHERS (SPatial data Integraction from Distributed and HEteRogeneous Sources – Integración de Datos Espaciales a partir de Fuentes Heterogéneas y Distribuidas basado en técnicas de mediación, recuperación, análisis y extracción eficientes de datos. Finalmente, este trabajo muestra la forma en que se puede utilizar la tecnología producida en SPIDHERS para integrar, analizar y tomar decisiones utilizando datos del Popocatépetl, volcán ubicado en la región de Puebla y la Ciudad de México.

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

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio

    2010-01-01

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

  8. Survey gear calibration independent of spatial fish distribution

    DEFF Research Database (Denmark)

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

    2004-01-01

    Trawl surveys provide important information for evaluation of relative stock abundance fluctuations over time. Therefore, when survey gears or vessels are changed, it is important to compare the efficiency and selectivity of old and new gears and vessels. A method for estimation of conversion...... and disturbance parameters with their precision are obtained using standard software. Simulation studies carried out additionally showed that the estimated conversion factors were practically unbiased. Because of the independence of the spatial fish distribution, the new method is preferable to the traditional...... paired hauls design for which it is generally not possible to obtain the statistical properties of the estimated conversion factors. The paper is concluded with suggestions on how to optimize survey design. The method was used to estimate conversion factors for Atlantic cod (Gadus morhua) from Danish...

  9. 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.

  10. Spatial Distribution of Dopant Incorporation in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt; Al-Jassim, Mowafak

    2016-11-21

    In this work we use state-of-the-art cathodoluminescence (CL) spectrum imaging that provides spectrum-per-pixel mapping of the CL emission to examine how dopant elements are incorporated into CdTe. Emission spectra and intensity are used to monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on theoretical modeling. Our results show that grain boundaries play a role in the incorporation of dopants in CdTe, whether intrinsic or extrinsic. This type of analysis is crucial for providing feedback to design different processing schedules that optimize dopant incorporation in CdTe photovoltaic material, which has struggled to reach high carrier concentration values. Here, we present results on CdTe films exposed to copper, phosphorus, and intrinsic doping treatments.

  11. Spatial distribution of Zika virus infection in Northeastern Colombia.

    Science.gov (United States)

    Rodriguez-Morales, Alfonso J; Haque, Ubydul; Ball, Jacob; García-Loaiza, Carlos Julian; Galindo-Marquez, Maria Leonor; Sabogal-Roman, Juan Alejandro; Marin-Loaiza, Santiago; Ayala, Andrés Felipe; Lozada-Riascos, Carlos O; Diaz-Quijano, Fredi A; Alvarado-Socarras, Jorge L

    2017-09-01

    In this study, we investigated the weekly reported spatio-temporal distribution and topographic risk factors for Zika virus (ZIKV) infection in northeastern Colombia. Weekly reported surveillance data, including clinical, suspected and confirmed cases from the ongoing ZIKV epidemic in the Santander and Norte de Santander departments (Santanderes) in Colombia were used to estimate cumulative incidence rates. Spatial analysis was performed to develop hot spot maps and to identify spatial topographic risk factors for infection. From January 1, 2016 to March 19, 2016, 11,515 cases of ZIKV were reported in Santanderes, with cumulative rates of 316.07 cases/100,000 population for the region (representing 18.5% of the cases of the country). Five municipalities (four in Norte de Santander) reported high incidence of ZIKV infection (>1,000 cases/100,000 pop); these municipalities are close to the border with Venezuela. Most of the cases reported occurred mainly in low altitude areas, and persistent hot spots were observed. Higher infection rates were reported in the Northeastern part of the study area. Use of risk maps can help guide decisions for the prevention and control of ZIKV. Hotspots on the Colombia-Venezuela border can have implications for international spread.

  12. Spatial and temporal distribution of urban heat islands.

    Science.gov (United States)

    Dos Santos, Alexandre Rosa; de Oliveira, Felício Santos; da Silva, Aderbal Gomes; Gleriani, José Marinaldo; Gonçalves, Wantuelfer; Moreira, Giselle Lemos; Silva, Felipe Gimenes; Branco, Elvis Ricardo Figueira; Moura, Marks Melo; da Silva, Rosane Gomes; Juvanhol, Ronie Silva; de Souza, Kaíse Barbosa; Ribeiro, Carlos Antonio Alvares Soares; de Queiroz, Vagner Tebaldi; Costa, Adilson Vidal; Lorenzon, Alexandre Simões; Domingues, Getulio Fonseca; Marcatti, Gustavo Eduardo; de Castro, Nero Lemos Martins; Resende, Rafael Tassinari; Gonzales, Duberli Elera; de Almeida Telles, Lucas Arthur; Teixeira, Thaisa Ribeiro; Dos Santos, Gleissy Mary Amaral Dino Alves; Mota, Pedro Henrique Santos

    2017-12-15

    The formation of an urban heat island (UHI) is one of the most common impacts of the urbanization process. To mitigate the effects of UHI, the planning of urban forests (e.g., creation of parks, forests and afforestation streets) has been the major tool applied in this context. Thus, the aim of this study is to evaluate the spatial and temporal distribution of heat islands in Vila Velha, ES, Brazil using the mono-window algorithm. The study followed these methodological steps: 1) mapping of urban green areas through a photointerpretation screen; 2) application of the mono-window algorithm to obtain the spatial and temporal patterns of land surface temperature (LST); 3) correlation between LST and the normalized difference vegetation index (NDVI) and normalized difference build-up index (NDBI); 4) application of ecological evaluation index. The results showed that the mean values of LST in urban areas were at least 2.34 to 7.19°C higher than undeveloped areas. Moreover, the positive correlation between LST and NDBI showed an amplifying effect of the developed areas for UHI, while areas with a predominance of vegetation attenuated the effect of UHI. Urban centers, clustered in some parts of the city, received the worst ecological assessment index. Finally, the adoption of measures to guide the urban forest planning within urban centers is necessary to mitigate the effect of heat islands and provide thermal comfort in urban areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Spatial distribution of surface hoar crystals in sparse forests

    Directory of Open Access Journals (Sweden)

    C. Shea

    2010-06-01

    Full Text Available Surface hoar size and location relate directly to avalanche initiation trigger points, and they do so in small-scale spatial distributions. Physically, surface hoar will grow where the snow surface is cold relative to the air and water vapour is plentiful. Vapour aside, snow cools at night primarily by longwave radiation emittance. Emittance can be restricted by clouds, trees, and terrain features. With 96 independent spatial point samples of surface hoar size, we show the extreme small-scale size variation that trees can create, ranging from 0 to 14 mm in an area of 402 m2. We relate this size variation to the effects of trees by using satellite photography to estimate the amount that trees impinge on sky view for each point. Though physically related to longwave escape, radiation balance can be as difficult to estimate as surface hoar size itself. Thus, we estimate point surface hoar size by expected maximum areal crystal size and dry terrain greyscale value only. We confirm this relation by using it at a different area and in a different formation cycle. There, its overall average error was 1.5 mm for an area with surface hoar sizes ranging from 0 to 7 mm.

  14. 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.

  15. Generating Distributed Forcing Fields for Spatial Hydrologic Modeling

    Science.gov (United States)

    Nayak, A.; Marks, D.; Chandler, D.; Winstral, A.

    2006-12-01

    Spatial hydrologic modeling requires the development of distributed forcing fields of weather and precipitation. This is particularly difficult in mountainous regions of the western US, where measurement sites are limited and the landscape is dominated by complex terrain and variations in vegetation cover. The Reynolds Creek Experimental Watershed (RCEW), in southwestern Idaho offers a unique opportunity to evaluate the sensitivity of interpolation techniques to the number and location of measurement sites. The RCEW, a 239 km2 hydro-climatic observatory operated by the USDA Agricultural Research Service since the early 1960's, contains 36 hydro-climatic measurement sites for monitoring the range of weather, snow and precipitation conditions across this complex mountain watershed. The MicroMet weather distribution utility, a process and topographically based weather interpolation tool (Liston and Elder, 2006), is used to generate surfaces of temperature, humidity, wind and precipitation over the snow-dominated 55 km2 (elevation range1398-2244m) Tollgate sub-catchment of RCEW. Nineteen meteorological stations were used to simulate the distribution of weather and precipitation for a series of storms during the 2004 water year. Measured and simulated values were compared to evaluate the accuracy of the model, and a jackknife approach was used to evaluate its sensitivity to data from particular stations. To evaluate the effect of elevation and storm track, different combinations of stations were selected, and to evaluate topographic exposure and vegetation shelter stations were divided into groups based on wind exposure. Results show that, even using a sophisticated weather distribution utility like MicroMet, the interpolation is very sensitive to station location and wind exposure. A certain amount of smoothing occurs even when using all 19 stations, but significant differences occur if only protected sites (similar to NRCS Snotel sites), or only wind-exposed sites are

  16. A simple consensus algorithm for distributed averaging in random ...

    Indian Academy of Sciences (India)

    guaranteed convergence with this simple algorithm. Keywords. Sensor networks; random geographical networks; distributed averaging; consensus algorithms. PACS Nos 89.75.Hc; 89.75.Fb; 89.20.Ff. 1. Introduction. Wireless sensor networks are increasingly used in many applications ranging from envi- ronmental to ...

  17. Random graphs with arbitrary degree distributions and their applications

    Science.gov (United States)

    Newman, M. E. J.; Strogatz, S. H.; Watts, D. J.

    2001-08-01

    Recent work on the structure of social networks and the internet has focused attention on graphs with distributions of vertex degree that are significantly different from the Poisson degree distributions that have been widely studied in the past. In this paper we develop in detail the theory of random graphs with arbitrary degree distributions. In addition to simple undirected, unipartite graphs, we examine the properties of directed and bipartite graphs. Among other results, we derive exact expressions for the position of the phase transition at which a giant component first forms, the mean component size, the size of the giant component if there is one, the mean number of vertices a certain distance away from a randomly chosen vertex, and the average vertex-vertex distance within a graph. We apply our theory to some real-world graphs, including the world-wide web and collaboration graphs of scientists and Fortune 1000 company directors. We demonstrate that in some cases random graphs with appropriate distributions of vertex degree predict with surprising accuracy the behavior of the real world, while in others there is a measurable discrepancy between theory and reality, perhaps indicating the presence of additional social structure in the network that is not captured by the random graph.

  18. Ultrathin wide bandwidth metamaterial absorber using randomly distributed scatterers

    Science.gov (United States)

    Ahmadi, Farzad; Ida, Nathan

    2017-02-01

    In this paper, a broadband, ultrathin metamaterial absorber (MA) using randomly distributed scatterers is presented. Each scattering element consists of two parallel strips. These elements can either be isolated or they may overlap with nearby elements. Three different randomly positioned structures are investigated for normal incident angle as well as oblique incident angles showing that these MAs can provide broadband absorption for all cases. The results presented here coincide with some previous works. Each structure obviously has different absorption spectrum and FWHM since the coupling between the randomly positioned scatterers is different in each case. The coupling between neighboring isolated and clustered scatterers form many resonating modes resulting in broadband absorption. The distribution of the electromagnetic fields are analyzed to obtain the physical behavior of the absorber. This shows that promising results can still be obtained for MAs when there is a significant tolerance distance between scatterers due to fabrication errors in micro and nanoscale metadevices.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jehouani, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)], E-mail: jehouani@ucam.ac.ma; Merzouki, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco); Remote Sensing and Geomatics of the Environment Laboratory, Ottawa-Carleton Geoscience Centre, Marion Hall, 140 Louis Pasteur, Ottawa, ON, KIN 6N5 (Canada); Boutadghart, F.; Ghassoun, J. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)

    2007-10-15

    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{sup *} 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. ].

  20. Spatial distribution of laminar flow-assisted dendritic amplification.

    Science.gov (United States)

    Hosokawa, Kazuo; Maeda, Mizuo

    2009-02-07

    In this paper, we report spatial distribution of laminar flow-assisted dendritic amplification (LFDA) product. LFDA is a recently invented signal amplification method dedicated to biomolecular binding events on microchannel walls. Onto the bound biomolecule, a dendritic structure is constructed by supplying two building blocks from laminar streams produced by a Y-shaped microchannel. In view of the extension of LFDA to simultaneous amplification of multiple binding spots, we have investigated the distribution of the LFDA product across and along the microchannel with the course of time. We fabricated a Y-shaped microchannel with a cross section of 110 microm x 22 microm using poly(dimethylsiloxane). As the LFDA building blocks, FITC-labeled streptavidin and biotinylated anti-streptavidin were injected from the two inlets of the microchannel at a mean flow velocity of 6.2 mm s(-1) (after the confluence). Nonspecific adsorption of the building blocks formed the seed layer of LFDA. The progress of LFDA was monitored with a fluorescence microscope up to 10.1 mm of microchannel length. After 5 min or later, the fluorescence intensity profile across the microchannel showed a peak at the center of the channel. With the course of time, the peak height grew exponentially except for slight saturation, but the peak width was almost constant. Along the microchannel, the peak height decreased almost linearly with the increasing logarithm of the distance, and the peak width was broadened in accordance with the 1/3 power law.

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

    Science.gov (United States)

    Pineux, Nathalie; Gilles, Colinet; Degré, Aurore

    2013-04-01

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

  2. Nonparametric Estimation of Distributions in Random Effects Models

    KAUST Repository

    Hart, Jeffrey D.

    2011-01-01

    We propose using minimum distance to obtain nonparametric estimates of the distributions of components in random effects models. A main setting considered is equivalent to having a large number of small datasets whose locations, and perhaps scales, vary randomly, but which otherwise have a common distribution. Interest focuses on estimating the distribution that is common to all datasets, knowledge of which is crucial in multiple testing problems where a location/scale invariant test is applied to every small dataset. A detailed algorithm for computing minimum distance estimates is proposed, and the usefulness of our methodology is illustrated by a simulation study and an analysis of microarray data. Supplemental materials for the article, including R-code and a dataset, are available online. © 2011 American Statistical Association.

  3. A random spatial sampling method in a rural developing nation

    Science.gov (United States)

    Michelle C. Kondo; Kent D.W. Bream; Frances K. Barg; Charles C. Branas

    2014-01-01

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method...

  4. 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

  5. A clustering analysis of eddies' spatial distribution in the South China Sea

    Directory of Open Access Journals (Sweden)

    J. Yi

    2013-02-01

    Full Text Available Spatial variation is important for studying the mesoscale eddies in the South China Sea (SCS. To investigate such spatial variations, this study made a clustering analysis on eddies' distribution using the K-means approach. Results showed that clustering tendency of anticyclonic eddies (AEs and cyclonic eddies (CEs were weak but not random, and the number of clusters were proved greater than four. Finer clustering results showed 10 regions where AEs densely populated and 6 regions for CEs in the SCS. Previous studies confirmed these partitions and possible generation mechanisms were related. Comparisons between AEs and CEs revealed that patterns of AE are relatively more aggregated than those of CE, and specific distinctions were summarized: (1 to the southwest of Luzon Island, AEs and CEs are generated spatially apart; AEs are likely located north of 14° N and closer to shore, while CEs are to the south and further offshore. (2 The central SCS and Nansha Trough are mostly dominated by AEs. (3 Along 112° E, clusters of AEs and CEs are located sequentially apart, and the pairs off Vietnam represent the dipole structures. (4 To the southwest of the Dongsha Islands, AEs are concentrated to the east of CEs. Overlaps of AEs and CEs in the northeastern and southern SCS were further examined considering seasonal variations. The northeastern overlap represented near-concentric distributions while the southern one was a mixed effect of seasonal variations, complex circulations and topography influences.

  6. Spatial and Temporal Distribution of Tuberculosis in the State of Mexico, Mexico

    Science.gov (United States)

    Zaragoza Bastida, Adrian; Hernández Tellez, Marivel; Bustamante Montes, Lilia P.; Medina Torres, Imelda; Jaramillo Paniagua, Jaime Nicolás; Mendoza Martínez, Germán David; Ramírez Durán, Ninfa

    2012-01-01

    Tuberculosis (TB) is one of the oldest human diseases that still affects large population groups. According to the World Health Organization (WHO), there were approximately 9.4 million new cases worldwide in the year 2010. In Mexico, there were 18,848 new cases of TB of all clinical variants in 2010. The identification of clusters in space-time is of great interest in epidemiological studies. The objective of this research was to identify the spatial and temporal distribution of TB during the period 2006–2010 in the State of Mexico, using geographic information system (GIS) and SCAN statistics program. Nine significant clusters (P Mexico is not randomly distributed but is concentrated in areas close to Mexico City. PMID:22919337

  7. Spatial distribution of moisture and its relation with soil texture

    Directory of Open Access Journals (Sweden)

    Kenneth Largaespada

    2015-11-01

    Full Text Available At Esmeralda Farm (Guácimo, Limón Province, C.R., planted to banana cv. Valery, the spatial distribution of soil humidity, and its relationship to some physical properties, were analyzed to determine the variability between the traditional method and use of TDR (Time Domain Reflectrometer in the determination of soil humidity. Sampling was done in a quadricuar pattern, with 36 measurement points georeferenced by GPS at 2 soil depths. At each point the volumetric soil water was measured with 3 different TDR equipments (300, MP and MT, and compared with the traditional method of volumetric humidity (VHM determination. Soil samples were also collected, for texture analysis; with these data, a geostatistical analysis was performed and the corresponding maps were drafted. The soils, of Loam to clayey Loam texture, showed variability between TDR and these determinations regarding the MHV, regardless of depth. On the surface, the highest correlation was found between the values of MHV and TDR-300 (r=0.69, followed by TDRMT (r=0.63 and finally the TDR-MP (r=0.59. At 30 to 60 cm depth, a positive but lower ratio values was found compared MHV with TRD- 300 and TDR-MP (0.47 and 0.38, respectively; no relationship was found with TDR-MT at this depth. In terms of field moisture map, a good representation between methods was found and it can be said that this method was effective in representing the spatial variation of soil moisture.

  8. 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.

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

    Science.gov (United States)

    Chen, Jing M.; Ju, Weimin; Cihlar, Josef; Price, David; Liu, Jane; Chen, Wenjun; Pan, Jianjun; Black, Andy; Barr, Alan

    2003-04-01

    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 CO2 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, CO2 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.

  10. [Analysis of spatial distribution of artemisinin in Artemisia annua in China].

    Science.gov (United States)

    Zhang, Xiao-Bo; Guo, Lan-Ping; Qiu, Zhi-Dong; Qu, Xiao-Bo; Wang, Hui; Jing, Zhi-Xian; Huang, Lu-Qi

    2017-11-01

    Geo-herbals are preferred by long-term clinical application of Chinese medicine, they are produced in a specific area and affected by the specific production and processing methods. Geo-herbals have a high reputation, compared with other regions produced by the same kind of herbs with good quality, efficacy and stable quality characteristics. Geo-herbal is a unique concept that has been formed by the history of Chinese civilization for thousands of years and the history of Chinese medicine. According to the definition of geo-herbal, it can be seen that there are some differences in the quality and efficacy of the same kind of medicinal herbs in different regions, and there is some similarity in the specific area. In this study, the spatial distribution characteristics of artemisinin in Artemisia annua were analyzed by spatial statistical analysis. ①The spatial autocorrelation of artemisinin content was analyzed by "I coefficient". The results showed that the content of artemisinin in each province was significant and positive spatial autocorrelation. The content of artemisinin in each province was not randomly distributed, but with a clear spatial aggregation characteristics. ②The spatial variability of artemisinin content was analyzed by "G statistic". The results showed that the area with high content of artemisinin was distributed in the southwest region, and the content of artemisinin was concentrated in the space, which tends to accumulate at high value. The content of artemisinin in Tianjin and Liaoning province is low, and it tends to accumulate at low value, while the content of artemisinin in other provinces is the transition zone of high and low value. ③Based on the index of artemisinin in each province, the spatial correlation of artemisinin content in each region was analyzed by "moran scatter plot". The results showed that the content of artemisinin in nine provinces such as Guangxi and Chongqing belonged to high value gathering area. ④Based on

  11. Randomized Algorithms for Tracking Distributed Count, Frequencies, and Ranks

    DEFF Research Database (Denmark)

    Huang, Zengfeng; Yi, Ke; Zhang, Qin

    2011-01-01

    $-approximation of their sum $n=\\sum_i n_i$ continuously at all times, using minimum communication. While the deterministic communication complexity of the problem is $\\Theta(k/\\eps \\cdot \\log N)$, where $N$ is the final value of $n$ when the tracking finishes, we show that with randomization, the communication cost can......We show that randomization can lead to significant improvements for a few fundamental problems in distributed tracking. Our basis is the {\\em count-tracking} problem, where there are $k$ players, each holding a counter $n_i$ that gets incremented over time, and the goal is to track an $\\eps...

  12. Randomized algorithms for tracking distributed count, frequencies, and ranks

    DEFF Research Database (Denmark)

    Zengfeng, Huang; Ke, Yi; Zhang, Qin

    2012-01-01

    of their sum n=∑ini continuously at all times, using minimum communication. While the deterministic communication complexity of the problem is θ(k/ε • log N), where N is the final value of n when the tracking finishes, we show that with randomization, the communication cost can be reduced to θ(√k/ε • log N......We show that randomization can lead to significant improvements for a few fundamental problems in distributed tracking. Our basis is the count-tracking problem, where there are k players, each holding a counter ni that gets incremented over time, and the goal is to track an ∑-approximation...

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  14. A spatial error model with continuous random effects and an application to growth convergence

    Science.gov (United States)

    Laurini, Márcio Poletti

    2017-10-01

    We propose a spatial error model with continuous random effects based on Matérn covariance functions and apply this model for the analysis of income convergence processes (β -convergence). The use of a model with continuous random effects permits a clearer visualization and interpretation of the spatial dependency patterns, avoids the problems of defining neighborhoods in spatial econometrics models, and allows projecting the spatial effects for every possible location in the continuous space, circumventing the existing aggregations in discrete lattice representations. We apply this model approach to analyze the economic growth of Brazilian municipalities between 1991 and 2010 using unconditional and conditional formulations and a spatiotemporal model of convergence. The results indicate that the estimated spatial random effects are consistent with the existence of income convergence clubs for Brazilian municipalities in this period.

  15. Mapping spatial distribution of forest age in China

    Science.gov (United States)

    Zhang, Yuan; Yao, Yitong; Wang, Xuhui; Liu, Yongwen; Piao, Shilong

    2017-03-01

    Forest stand age is a meaningful metric, which reflects the past disturbance legacy, provides guidelines for forest management practices, and is an important factor in qualifying forest carbon cycles and carbon sequestration potential. Reliable large-scale forest stand age information with high spatial resolutions, however, is difficult to obtain. In this study, we developed a top-down method to downscale the provincial statistics of national forest inventory data into 1 km stand age map using climate data and light detection and ranging-derived forest height. We find that the distribution of forest stand age in China is highly heterogeneous across the country, with a mean value of 42.6 years old. The relatively young stand age for Chinese forests is mostly due to the large proportion of newly planted forests (0-40 years old), which are more prevailing in south China. Older forests (stand age > 60 years old) are more frequently found in east Qinghai-Tibetan Plateau and the central mountain areas of west and northeast China, where human activities are less intensive. Among the 15 forest types, forests dominated by species of Taxodiaceae, with the exception of Cunninghamia lanceolata stands, have the oldest mean stand age (136 years), whereas Pinus massoniana forests are the youngest (18 years). We further identified uncertainties associated with our forest age map, which are high in west and northeast China. Our work documents the distribution of forest stand age in China at a high resolution which is useful for carbon cycle modeling and the sustainable use of China's forest resources.

  16. On the Inference of Spatial Continuity using Spartan Random Field Models

    OpenAIRE

    Elogne, Samuel; Hristopulos, Dionisis

    2006-01-01

    This paper addresses the inference of spatial dependence in the context of a recently proposed framework. More specifically, the paper focuses on the estimation of model parameters for a class of generalized Gibbs random fields, i.e., Spartan Spatial Random Fields (SSRFs). The problem of parameter inference is based on the minimization of a distance metric. The latter involves a specifically designed distance between sample constraints (variance, generalized ``gradient'' and ``curvature'') an...

  17. Computer routines for probability distributions, random numbers, and related functions

    Science.gov (United States)

    Kirby, W.

    1983-01-01

    Use of previously coded and tested subroutines simplifies and speeds up program development and testing. This report presents routines that can be used to calculate various probability distributions and other functions of importance in statistical hydrology. The routines are designed as general-purpose Fortran subroutines and functions to be called from user-written main progress. The probability distributions provided include the beta, chi-square, gamma, Gaussian (normal), Pearson Type III (tables and approximation), and Weibull. Also provided are the distributions of the Grubbs-Beck outlier test, Kolmogorov 's and Smirnov 's D, Student 's t, noncentral t (approximate), and Snedecor F. Other mathematical functions include the Bessel function, I sub o, gamma and log-gamma functions, error functions, and exponential integral. Auxiliary services include sorting and printer-plotting. Random number generators for uniform and normal numbers are provided and may be used with some of the above routines to generate numbers from other distributions. (USGS)

  18. Peer-Assisted Content Distribution with Random Linear Network Coding

    DEFF Research Database (Denmark)

    Hundebøll, Martin; Ledet-Pedersen, Jeppe; Sluyterman, Georg

    2014-01-01

    Peer-to-peer networks constitute a widely used, cost-effective and scalable technology to distribute bandwidth-intensive content. The technology forms a great platform to build distributed cloud storage without the need of a central provider. However, the majority of todays peer-to-peer systems...... require complex algorithms to schedule what parts of obtained content to forward to other peers. Random Linear Network Coding can greatly simplify these algorithm by removing the need for coordination between the distributing nodes. In this paper we propose and evaluate the structure of the BRONCO peer-to-peer....... Furthermore, we evaluate the performance of different parameters and suggest a suitable trade-off between CPU utilization and network overhead. Within the limitations of the used test environment, we have shown that networkc coding is usable in peer-assisted content distribution and we suggest further...

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

    Science.gov (United States)

    Moll, Julia; Hoppe, Björn; König, Stephan; Wubet, Tesfaye; Buscot, François; Krüger, Dirk

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Julia Moll

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

  1. 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

  2. Spatial Random Field Models Inspired from Statistical Physics with Applications in the Geosciences

    OpenAIRE

    Hristopulos, D. T.

    2005-01-01

    The spatial structure of fluctuations in spatially inhomogeneous processes can be modeled in terms of Gibbs random fields. A local low energy estimator (LLEE) is proposed for the interpolation (prediction) of such processes at points where observations are not available. The LLEE approximates the spatial dependence of the data and the unknown values at the estimation points by low-lying excitations of a suitable energy functional. It is shown that the LLEE is a linear, unbiased, non-exact est...

  3. Graphene materials having randomly distributed two-dimensional structural defects

    Science.gov (United States)

    Kung, Harold H; Zhao, Xin; Hayner, Cary M; Kung, Mayfair C

    2013-10-08

    Graphene-based storage materials for high-power battery applications are provided. The storage materials are composed of vertical stacks of graphene sheets and have reduced resistance for Li ion transport. This reduced resistance is achieved by incorporating a random distribution of structural defects into the stacked graphene sheets, whereby the structural defects facilitate the diffusion of Li ions into the interior of the storage materials.

  4. Random generation of RNA secondary structures according to native distributions

    Directory of Open Access Journals (Sweden)

    Nebel Markus E

    2011-10-01

    Full Text Available Abstract Background Random biological sequences are a topic of great interest in genome analysis since, according to a powerful paradigm, they represent the background noise from which the actual biological information must differentiate. Accordingly, the generation of random sequences has been investigated for a long time. Similarly, random object of a more complicated structure like RNA molecules or proteins are of interest. Results In this article, we present a new general framework for deriving algorithms for the non-uniform random generation of combinatorial objects according to the encoding and probability distribution implied by a stochastic context-free grammar. Briefly, the framework extends on the well-known recursive method for (uniform random generation and uses the popular framework of admissible specifications of combinatorial classes, introducing weighted combinatorial classes to allow for the non-uniform generation by means of unranking. This framework is used to derive an algorithm for the generation of RNA secondary structures of a given fixed size. We address the random generation of these structures according to a realistic distribution obtained from real-life data by using a very detailed context-free grammar (that models the class of RNA secondary structures by distinguishing between all known motifs in RNA structure. Compared to well-known sampling approaches used in several structure prediction tools (such as SFold ours has two major advantages: Firstly, after a preprocessing step in time O(n2 for the computation of all weighted class sizes needed, with our approach a set of m random secondary structures of a given structure size n can be computed in worst-case time complexity Om⋅n⋅ log(n while other algorithms typically have a runtime in O(m⋅n2. Secondly, our approach works with integer arithmetic only which is faster and saves us from all the discomforting details of using floating point arithmetic with

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

    Science.gov (United States)

    Barbieri, Flavia L; Gardon, Jacques

    2009-12-21

    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. 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. 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 microg/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. 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 majority of the Amazonian populations can be considered exposed

  6. 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

  7. 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

  8. Strong Predictability Of Spatially Distributed Physical Habitat Preferences For O. Mykiss Spawning Across Three Spatial Scales

    Science.gov (United States)

    Kammel, L.; Pasternack, G. B.; Wyrick, J. R.; Massa, D.; Bratovich, P.; Johnson, T.

    2012-12-01

    Currently accepted perception assumes Oncorhynchus mykiss prefer different ranges of similar physical habitat elements for spawning than Chinook salmon (Oncorhynchus tshawytscha), taking into account their difference in size. While there is increasing research interest regarding O. mykiss habitat use and migratory behavior, research conducted to date distinguishing the physical habitat conditions utilized for O. mykiss spawning has not provided quantified understanding of their spawning habitat preferences. The purpose of this study was to use electivity indices and other measures to assess the physical habitat characteristics preferred for O. mykiss spawning in terms of both 1-m scale microhabitat attributes, and landforms at different spatial scales from 0.1-100 times channel width. The testbed for this study was the 37.5-km regulated gravel-cobble Lower Yuba River (LYR). Using spatially distributed 2D hydrodynamic model results, substrate mapping, and a census of O. mykiss redds from two years of observation, micro- and meso-scale representations of physical habitat were tested for their ability to predict spawning habitat preference and avoidance. Overall there was strong stratification of O. mykiss redd occurrence for all representation types of physical habitat. A strong preference of hydraulic conditions was shown for mean water column velocities of 1.18-2.25 ft/s, and water depths of 1.25-2.76 ft. There was a marked preference for the two most upstream alluvial reaches of the LYR (out of 8 total reaches), accounting for 92% of all redds observed. The preferred morphological units (MUs) for O. mykiss spawning were more variable than for Chinook salmon and changed with increasing discharge, demonstrating that O. mykiss shift spawning to different MUs in order to utilize their preferred hydraulic conditions. The substrate range preferred for O. mykiss spawning was within 32-90 mm. Overall, O. mykiss spawning behavior was highly predictable and required a

  9. Spatial Distribution Patterns in the Very Rare and Species-Rich Picea chihuahuana Tree Community (Mexico)

    Science.gov (United States)

    Wehenkel, Christian; Brazão-Protázio, João Marcelo; Carrillo-Parra, Artemio; Martínez-Guerrero, José Hugo; Crecente-Campo, Felipe

    2015-01-01

    The very rare Mexican Picea chihuahuana tree community covers an area of no more than 300 ha in the Sierra Madre Occidental. This special tree community has been the subject of several studies aimed at learning more about the genetic structure and ecology of the species and the potential effects of climate change. The spatial distribution of trees is a result of many ecological processes and can affect the degree of competition between neighbouring trees, tree density, variability in size and distribution, regeneration, survival, growth, mortality, crown formation and the biological diversity within forest communities. Numerous scale-dependent measures have been established in order to describe spatial forest structure. The overall aim of most of these studies has been to obtain data to help design preservation and conservation strategies. In this study, we examined the spatial distribution pattern of trees in the P. chihuahuana tree community in 12 localities, in relation to i) tree stand density, ii) diameter distribution (vertical structure), iii) tree species diversity, iv) geographical latitude and v) tree dominance at a fine scale (in 0.25 ha plots), with the aim of obtaining a better understanding of the complex ecosystem processes and biological diversity. Because of the strongly mixed nature of this tree community, which often produces low population densities of each tree species and random tree fall gaps caused by tree death, we expect aggregated patterns in individual Picea chihuahuana trees and in the P. chihuahuana tree community, repulsive Picea patterns to other tree species and repulsive patterns of young to adult trees. Each location was represented by one plot of 50 x 50 m (0.25 ha) established in the centre of the tree community. The findings demonstrate that the hypothesis of aggregated tree pattern is not applicable to the mean pattern measured by Clark-Evans index, Uniform Angle index and Mean Directional index of the uneven-aged P

  10. Spatial Distribution Patterns in the Very Rare and Species-Rich Picea chihuahuana Tree Community (Mexico.

    Directory of Open Access Journals (Sweden)

    Christian Wehenkel

    Full Text Available The very rare Mexican Picea chihuahuana tree community covers an area of no more than 300 ha in the Sierra Madre Occidental. This special tree community has been the subject of several studies aimed at learning more about the genetic structure and ecology of the species and the potential effects of climate change. The spatial distribution of trees is a result of many ecological processes and can affect the degree of competition between neighbouring trees, tree density, variability in size and distribution, regeneration, survival, growth, mortality, crown formation and the biological diversity within forest communities. Numerous scale-dependent measures have been established in order to describe spatial forest structure. The overall aim of most of these studies has been to obtain data to help design preservation and conservation strategies. In this study, we examined the spatial distribution pattern of trees in the P. chihuahuana tree community in 12 localities, in relation to i tree stand density, ii diameter distribution (vertical structure, iii tree species diversity, iv geographical latitude and v tree dominance at a fine scale (in 0.25 ha plots, with the aim of obtaining a better understanding of the complex ecosystem processes and biological diversity. Because of the strongly mixed nature of this tree community, which often produces low population densities of each tree species and random tree fall gaps caused by tree death, we expect aggregated patterns in individual Picea chihuahuana trees and in the P. chihuahuana tree community, repulsive Picea patterns to other tree species and repulsive patterns of young to adult trees. Each location was represented by one plot of 50 x 50 m (0.25 ha established in the centre of the tree community. The findings demonstrate that the hypothesis of aggregated tree pattern is not applicable to the mean pattern measured by Clark-Evans index, Uniform Angle index and Mean Directional index of the uneven

  11. p-value approximations for spatial scan statistics using extreme value distributions.

    Science.gov (United States)

    Jung, Inkyung; Park, Goeun

    2015-02-10

    Spatial scan statistics are widely applied to identify spatial clusters in geographic disease surveillance. To evaluate the statistical significance of detected clusters, Monte Carlo hypothesis testing is often used because the null distribution of spatial scan statistics is not known. A drawback of the method is that we have to increase the number of replications to obtain accurate p-values. Gumbel-based p-value approximations for spatial scan statistics have recently been proposed and evaluated for Poisson and Bernoulli models. In this study, we examine the use of a generalized extreme value distribution to approximate the null distribution of spatial scan statistics as well as the Gumbel distribution. Through simulation, p-value approximations using extreme value distributions for spatial scan statistics are assessed for multinomial and ordinal models in addition to Poisson and Bernoulli models. Copyright © 2014 John Wiley & Sons, Ltd.

  12. 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

  13. 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.

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

    Science.gov (United States)

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

    2017-10-01

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

  15. Optimal dynamics for quality control in spatially distributed mitochondrial networks.

    Directory of Open Access Journals (Sweden)

    Pinkesh K Patel

    Full Text Available Recent imaging studies of mitochondrial dynamics have implicated a cycle of fusion, fission, and autophagy in the quality control of mitochondrial function by selectively increasing the membrane potential of some mitochondria at the expense of the turnover of others. This complex, dynamical system creates spatially distributed networks that are dependent on active transport along cytoskeletal networks and on protein import leading to biogenesis. To study the relative impacts of local interactions between neighboring mitochondria and their reorganization via transport, we have developed a spatiotemporal mathematical model encompassing all of these processes in which we focus on the dynamics of a health parameter meant to mimic the functional state of mitochondria. In agreement with previous models, we show that both autophagy and the generation of membrane potential asymmetry following a fusion/fission cycle are required for maintaining a healthy mitochondrial population. This health maintenance is affected by mitochondrial density and motility primarily through changes in the frequency of fusion events. Health is optimized when the selectivity thresholds for fusion and fission are matched, providing a mechanistic basis for the observed coupling of the two processes through the protein OPA1. We also demonstrate that the discreteness of the components exchanged during fusion is critical for quality control, and that the effects of limiting total amounts of autophagy and biogenesis have distinct consequences on health and population size, respectively. Taken together, our results show that several general principles emerge from the complexity of the quality control cycle that can be used to focus and interpret future experimental studies, and our modeling framework provides a road-map for deconstructing the functional importance of local interactions in communities of cells as well as organelles.

  16. Spatial sensitivity analysis of snow cover data in a distributed rainfall-runoff model

    National Research Council Canada - National Science Library

    Berezowski, T; Nossent, J; Chormański, J; Batelaan, O

    2015-01-01

    As the availability of spatially distributed data sets for distributed rainfall-runoff modelling is strongly increasing, more attention should be paid to the influence of the quality of the data on the calibration...

  17. Spatial quantum correlations induced by random multiple scattering of quadrature squeezed light

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2007-01-01

    The authors demonstrates that spatial quantum correlations are induced by multiple scattering of quadrature squeezed light through a random medium. As a consequence, light scattered along two different directions by the random medium will not be independent, but be correlated to an extent that ca...... only be described by a quantum mechanical theory for multiple scattering. The spatial quantum correlation is revealed in the fluctuations of the total intensity transmission or reflection through the multiple scattering medium.......The authors demonstrates that spatial quantum correlations are induced by multiple scattering of quadrature squeezed light through a random medium. As a consequence, light scattered along two different directions by the random medium will not be independent, but be correlated to an extent that can...

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

    Science.gov (United States)

    Russell A. Parsons

    2006-01-01

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

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

    African Journals Online (AJOL)

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

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

    African Journals Online (AJOL)

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

  1. Spatial Distribution of Plant-Parasitic Nematodes in Semi-Arid Vitis vinifera Vineyards in Washington.

    Science.gov (United States)

    Howland, Amanda D; Schreiner, R Paul; Zasada, Inga A

    2014-12-01

    The most commonly encountered plant-parasitic nematodes in eastern Washington Vitis vinifera vineyards are Meloidogyne hapla, Mesocriconema xenoplax, Pratylenchus spp., Xiphinema americanum, and Paratylenchus sp.; however, little is known about their distribution in the soil profile. The vertical and horizontal spatial distribution of plant-parasitic nematodes was determined in two Washington V. vinifera vineyards. Others variables measured in these vineyards included soil moisture content, fine root biomass, and root colonization by arbuscular mycorhizal fungi (AMF). Meloidogyne hapla and M. xenoplax were aggregated under irrigation emitters within the vine row and decreased with soil depth. Conversely, Pratylenchus spp. populations were primarily concentrated in vineyard alleyways and decreased with depth. Paratylenchus sp. and X. americanum were randomly distributed within the vineyards. Soil water content played a dominant role in the distribution of fine roots and plant-parasitic nematodes. Colonization of fine roots by AMF decreased directly under irrigation emitters; in addition, galled roots had lower levels of AMF colonization compared with healthy roots. These findings will help facilitate sampling and management decisions for plant-parasitic nematodes in Washington semi-arid vineyards.

  2. Pure random search for ambient sensor distribution optimisation in a smart home environment.

    Science.gov (United States)

    Poland, Michael P; Nugent, Chris D; Wang, Hui; Chen, Liming

    2011-01-01

    Smart homes are living spaces facilitated with technology to allow individuals to remain in their own homes for longer, rather than be institutionalised. Sensors are the fundamental physical layer with any smart home, as the data they generate is used to inform decision support systems, facilitating appropriate actuator actions. Positioning of sensors is therefore a fundamental characteristic of a smart home. Contemporary smart home sensor distribution is aligned to either a) a total coverage approach; b) a human assessment approach. These methods for sensor arrangement are not data driven strategies, are unempirical and frequently irrational. This Study hypothesised that sensor deployment directed by an optimisation method that utilises inhabitants' spatial frequency data as the search space, would produce more optimal sensor distributions vs. the current method of sensor deployment by engineers. Seven human engineers were tasked to create sensor distributions based on perceived utility for 9 deployment scenarios. A Pure Random Search (PRS) algorithm was then tasked to create matched sensor distributions. The PRS method produced superior distributions in 98.4% of test cases (n=64) against human engineer instructed deployments when the engineers had no access to the spatial frequency data, and in 92.0% of test cases (n=64) when engineers had full access to these data. These results thus confirmed the hypothesis.

  3. 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

  4. Topographical and Hydrological Influences on the Spatial Distribution of Mercury at the Catchment Scale

    Science.gov (United States)

    Gunda, T.; Converse, A.; Riscassi, A.; Scanlon, T. M.

    2009-12-01

    Inorganic forms of mercury (Hg) can be converted through natural processes into methylmercury, a highly potent neurotoxin that can bioaccumulate in food chains and pose a risk to human health. Although Hg can enter aquatic environments through direct deposition, the predominant source tends to be mobilized Hg deposited in nearby terrestrial systems. Therefore, understanding the complex intermediate Hg cycling in vegetation and soils is crucial to predicting its presence in water bodies and potential for bioaccumulation. While prior studies have revealed dependence of Hg distribution on forest types and soil characteristics, less attention has been given to the role of aspect and hydrological factors on Hg deposition and consequent spatial distribution within catchments. My research addresses this by conducting a litterfall and soil sampling study to assess Hg spatial distribution within two paired catchments: northwest-facing North Fork Dry Run and southeast-facing Hannah Run. Litterfall and soil samples collected through a random stratified sampling process were analyzed for total Hg concentrations using a Cold Vapor Atomic Fluorescence Spectrometry. An analysis of variance conducted on leaf litter and soil Hg concentrations revealed that: (1) Hg accumulation in soils was significantly greater in the northwest-facing catchment than in the south-east facing catchment, while Hg accumulation in leaves was not found to differ, and (2) within each catchment the likelihood of saturation was not found to play a significant role in governing Hg accumulation in soils. Higher Hg levels in the soils of North Forth Dry Run could be attributable to predominant wind direction from sources of Hg (i.e., coal-burning power plants). Within catchments, lack of appreciable Hg deposition resulted in statistically insignificant variation amongst topographic index classes. The results of this study reveal the potential implications of mountainous terrains in distributing Hg arising from

  5. Spatial location identification of structural nonlinearities from random data

    Science.gov (United States)

    Josefsson, A.; Magnevall, M.; Ahlin, K.; Broman, G.

    2012-02-01

    With growing demands on product performance and growing complexity of engineering structures, efficient tools for analyzing their dynamic behavior are essential. Linear techniques are well developed and often utilized. However, sometimes the errors due to linearization are too large to be acceptable, making it necessary to take nonlinear effects into account. In many practical applications it is common and reasonable to assume that the nonlinearities are highly local and thus only affect a limited set of spatial coordinates. The purpose of this paper is to present an approach to finding the spatial location of nonlinearities from measurement data, as this may not always be known beforehand. This information can be used to separate the underlying linear system from the nonlinear parts and create mathematical models for efficient parameter estimation and simulation. The presented approach builds on the reverse-path methodology and utilizes the coherence functions to determine the location of nonlinear elements. A systematic search with Multiple Input/Single Output models is conducted in order to find the nonlinear functions that best describe the nonlinear restoring forces. The obtained results indicate that the presented approach works well for identifying the location of local nonlinearities in structures. It is verified by simulation data from a cantilever beam model with two local nonlinearities and experimental data from a T-beam experimental set-up with a single local nonlinearity. A possible drawback is that a relatively large amount of data is needed. Advantages of the approach are that it only needs a single excitation point that response data at varying force amplitudes is not needed and that no prior information about the underlying linear system is needed.

  6. Acacia trees pattern distribution as an indicator for changes in flow spatial distributions in a hyper-arid environment

    Science.gov (United States)

    Isaacson, Sivan; Ephrath, Jhonathan E.; Rachmilevitch, Shimon; Maman, Shimrit; Blumberg, Dan G.

    2017-04-01

    Arid regions are characterized by high spatial and temporal variability of precipitation, resulting in high spatial and temporal variation of vegetation cover. Because of low rainfall, the acacia trees in southern Israel are usually restricted to ephemeral stream (Wadi) beds, which possess higher soil moisture content than the surrounding landscape. Spatial analyses of tree distribution at the drainage basin scale contributes to a better understanding of the geo-hydrologic regime because water is the main limiting factor in such areas. That is, the spatial distribution of trees and their characteristics within the Wadi may reflect the spatial variance of water availability within different segments of the Wadi. The main objective of this study was to use the spatial distribution of different parameters of acacia trees as an indicator of past and present hydrological regimes within different segments of the Wadi. Tree size distribution was used as an indicator of long-term (decades) geo-hydrologic spatial processes affecting the acacia population. The tree health (NDVI) distribution was used as an indicator of short-term (months to a few years) geo-hydrologic spatial processes, such as the paths of recent flashfloods events. The distribution of the trees in the Wadi (ephemeral river) was divided into three distinct categories: (1) large trees with high NDVI values, (2) large trees with low NDVI values and (3) small trees with medium NDVI values. Using the resulting classification, we divided the Wadi into three sections, each representing a unique combination of long- and short-term geo-hydrologic processes affecting the acacia trees. We suggest that the lack of spatial correlation between tree size and health status is a result of spatio-temporal changes in the water supply. Our main conclusion is that past and current alterations of the runoff path can be detected by the spatial analysis of trees in hyper-arid regions

  7. Random matrix approach to the distribution of genomic distance.

    Science.gov (United States)

    Alexeev, Nikita; Zograf, Peter

    2014-08-01

    The cycle graph introduced by Bafna and Pevzner is an important tool for evaluating the distance between two genomes, that is, the minimal number of rearrangements needed to transform one genome into another. We interpret this distance in topological terms and relate it to the random matrix theory. Namely, the number of genomes at a given 2-break distance from a fixed one (the Hultman number) is represented by a coefficient in the genus expansion of a matrix integral over the space of complex matrices with the Gaussian measure. We study generating functions for the Hultman numbers and prove that the two-break distance distribution is asymptotically normal.

  8. Damage Spreading in Spatial and Small-world Random Boolean Networks

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Qiming [Fermilab; Teuscher, Christof [Portland State U.

    2014-02-18

    The study of the response of complex dynamical social, biological, or technological networks to external perturbations has numerous applications. Random Boolean Networks (RBNs) are commonly used a simple generic model for certain dynamics of complex systems. Traditionally, RBNs are interconnected randomly and without considering any spatial extension and arrangement of the links and nodes. However, most real-world networks are spatially extended and arranged with regular, power-law, small-world, or other non-random connections. Here we explore the RBN network topology between extreme local connections, random small-world, and pure random networks, and study the damage spreading with small perturbations. We find that spatially local connections change the scaling of the relevant component at very low connectivities ($\\bar{K} \\ll 1$) and that the critical connectivity of stability $K_s$ changes compared to random networks. At higher $\\bar{K}$, this scaling remains unchanged. We also show that the relevant component of spatially local networks scales with a power-law as the system size N increases, but with a different exponent for local and small-world networks. The scaling behaviors are obtained by finite-size scaling. We further investigate the wiring cost of the networks. From an engineering perspective, our new findings provide the key design trade-offs between damage spreading (robustness), the network's wiring cost, and the network's communication characteristics.

  9. Runoff production on a slope with randomly distributed infiltrabilities

    Science.gov (United States)

    Mouche, E.; Harel, M.

    2013-12-01

    Runoff generated on one- and two-dimensional slopes with randomly distributed infiltrability is studied in the queuing theory and connectivity frameworks. The equivalence between the runoff-runon equation and the customers waiting time in a single server queue provides a theoretical link between the statistical descriptions of infiltrability and that of runoff flow rate. Different distributions of infiltrability, representing soil heterogeneities at different scales, are considered. Numerical simulations validate these results and improve our understanding of runoff-runon process. All of the quantities describing the generation of runoff (runoff one-point statistics) and its organization into patterns (patterns statistics and connectivity) are studied as functions of rainfall rate and runoff dimensionality.

  10. Spatial distribution of parasitism on Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae in citrus orchards

    Directory of Open Access Journals (Sweden)

    SM. Jahnke

    Full Text Available Many species of microhymenopterous parasitoids have been registered on Phyllocnistis citrella, the citrus leafminer. The present study aimed to identify the spatial distribution pattern of the native and introduced parasitoids of P. citrella in two citrus orchards in Montenegro, RS. The new shoots from 24 randomly selected trees in each orchard were inspected at the bottom (0-1.5 m and top (1.5-2.5 m stratum and had their position relative to the quadrants (North, South, East and West registered at every 15 days from July/2002 to June/2003. The leaves with pupae were collected and kept isolated until the emergence of parasitoids or of the leaf miner; so, the sampling was biased towards parasitoids that emerge in the host pupal phase. The horizontal spatial distribution was evaluated testing the fitness of data to the Poisson and negative binomial distributions. In Montenegrina, there was no significant difference in the number of parasitoids and in the mean number of pupae found in the top and bottom strata (χ2 = 0.66; df = 1; P > 0.05 (χ2 = 0.27; df =1; P > 0.05, respectively. In relation to the quadrants, the highest average numbers of the leafminer pupae and of parasitoids were registered at the East quadrant (χ2 = 11.81; df = 3; P < 0.05, (χ2 = 10.36; df = 3; P < 0.05. In the Murcott orchard, a higher number of parasitoids was found at the top stratum (63.5% (χ2 = 7.24; df =1 P < 0.05, the same occurring with the average number of P. citrella pupae (62.9% (χ2 = 6.66; df = 1; P < 0.05. The highest number of parasitoids and of miners was registered at the North quadrant (χ2 = 19. 29; df = 3; P < 0.05, (χ2 = 4.39; df = 3; P < 0.05. In both orchards, there was no difference between the numbers of shoots either relative to the strata as well as to the quadrants. As the number of shoots did not varied much relative to the quadrants, it is possible that the higher number of miners and parasitoids in the East and West quadrants would be

  11. 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.

  12. Importance of spatial autocorrelation in modeling bird distributions at a continental scale

    Science.gov (United States)

    Bahn, V.; O'Connor, R.J.; Krohn, W.B.

    2006-01-01

    Spatial autocorrelation in species' distributions has been recognized as inflating the probability of a type I error in hypotheses tests, causing biases in variable selection, and violating the assumption of independence of error terms in models such as correlation or regression. However, it remains unclear whether these problems occur at all spatial resolutions and extents, and under which conditions spatially explicit modeling techniques are superior. Our goal was to determine whether spatial models were superior at large extents and across many different species. In addition, we investigated the importance of purely spatial effects in distribution patterns relative to the variation that could be explained through environmental conditions. We studied distribution patterns of 108 bird species in the conterminous United States using ten years of data from the Breeding Bird Survey. We compared the performance of spatially explicit regression models with non-spatial regression models using Akaike's information criterion. In addition, we partitioned the variance in species distributions into an environmental, a pure spatial and a shared component. The spatially-explicit conditional autoregressive regression models strongly outperformed the ordinary least squares regression models. In addition, partialling out the spatial component underlying the species' distributions showed that an average of 17% of the explained variation could be attributed to purely spatial effects independent of the spatial autocorrelation induced by the underlying environmental variables. We concluded that location in the range and neighborhood play an important role in the distribution of species. Spatially explicit models are expected to yield better predictions especially for mobile species such as birds, even in coarse-grained models with a large extent. ?? Ecography.

  13. Spatial panel data models of aquaculture production in West Sumatra province with random-effects

    Science.gov (United States)

    Sartika, Wimi; Susetyo, Budi; Syafitri, Utami Dyah

    2017-03-01

    Spatial Panel Regression is a statistical model that used to analyze the effect of several independent variables on the dependent variable based on using panel data and take the spatial effect into account. There are two approaches on predicting spatial panel data, Fixed Effect Spatial Autoregressive (SAR-FE) and Random Effect Spatial Autoregressive (SAR-RE). SAR-FE has the assumption that the intercept has vary acrros spatial unit, while the SAR-RE's assumption is the interception is on residual model and it only has a general intercept. The purpose of this study is to modeling the production of West Sumatra fishery using Spatial Panel Regression. The model uses secondary data which is published by "Badan Pusat Statistik" on the results of aquaculture production in West Sumatra. The test results shown that the level of West Sumatra 2004-2012 aquaculture production was precisely modeled by the approach of Spatial Autoregressive Random Effect. From SAR-RE model, the most influence factors on aquaculture production in West Sumatra province in 2004-2012 was the number of motor boats, the area of fish seeds, fish seed production, and the number of fishermen public waters.

  14. 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.

  15. Weight Distributions for Turbo Codes Using Random and Nonrandom Permutations

    Science.gov (United States)

    Dolinar, S.; Divsalar, D.

    1995-04-01

    This article takes a preliminary look at the weight distributions achievable for turbo codes using random, nonrandom, and semirandom permutations. Due to the recursiveness of the encoders, it is important to distinguish between self-terminating and non-self-terminating input sequences. The non-self-terminating sequences have little effect on decoder performance, because they accumulate high encoded weight until they are artificially terminated at the end of the block. From probabilistic arguments based on selecting the permutations randomly, it is concluded that the self-terminating weight-2 data sequences are the most important consideration in the design of the constituent codes; higher-weight self-terminating sequences have successively decreasing importance. Also, increasing the number of codes and, correspondingly, the number of permutations makes it more and more likely that the bad input sequences will be broken up by one or more of the permuters. It is possible to design nonrandom permutations that ensure that the minimum distance due to weight-2 input sequences grows roughly as p 2N, where N is the block length. However, these nonrandom permutations amplify the bad effects of higher-weight inputs, and as a result they are inferior in performance to randomly selected permutations. But there are "semirandom" permutations that perform nearly as well as the designed nonrandom permutations with respect to weight-2 input sequences and are not as susceptible to being foiled by higher-weight inputs.

  16. Prediction of the spatial occurrence of fire induced spalling in concrete slabs using random fields

    Directory of Open Access Journals (Sweden)

    Van Coile R.

    2013-09-01

    Full Text Available As the loss of concrete cover can significantly influence the reliability of concrete elements during fire, spalling should be taken into account when performing reliability calculations. However, the occurrence and spatial variation of spalling are highly uncertain. A first step towards a probabilistic analysis of spalling is made by combining existing deterministic models with a stochastic representation of the concrete tensile strength and by using random fields to model the tensile strength spatial variation.

  17. 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

  18. Random and systematic spatial variability of 137Cs inventories at reference sites in South-Central Brazil

    Directory of Open Access Journals (Sweden)

    Correchel Vladia

    2005-01-01

    Full Text Available The precision of the 137Cs fallout redistribution technique for the evaluation of soil erosion rates is strongly dependent on the quality of an average inventory taken at a representative reference site. The knowledge of the sources and of the degree of variation of the 137Cs fallout spatial distribution plays an important role on its use. Four reference sites were selected in the South-Central region of Brazil which were characterized in terms of soil chemical, physical and mineralogical aspects as well as the spatial variability of 137Cs inventories. Some important differences in the patterns of 137Cs depth distribution in the soil profiles of the different sites were found. They are probably associated to chemical, physical, mineralogical and biological differences of the soils but many questions still remain open for future investigation, mainly those regarding the adsorption and dynamics of the 137Cs ions in soil profiles under tropical conditions. The random spatial variability (inside each reference site was higher than the systematic spatial variability (between reference sites but their causes were not clearly identified as possible consequences of chemical, physical, mineralogical variability, and/or precipitation.

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

    Indian Academy of Sciences (India)

    sediment transport rate for Chou-Shui river basin ... 5, Anzhong Road,. Tainan 70970, Taiwan. 4. Department of Hydraulics and Ocean Engineering, National Cheng-Kung University, No. 1,. University Road, Tainan ... surface runoff discharge, suspended sediment transport rate, quantity of soil erosion, and spatial distribu-.

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

    African Journals Online (AJOL)

    The rare opportunity given by the unprecedented spatial and temporal coverage of POGO satellites data is exploited to present all possible cross sections of equatorial electrojet (EEJ) current in the group of papers. Here the all-longitude means at 7 hours centred on local noon and the daytime means at 36 longitudes, of the ...

  1. Spatial and temporal distribution of methane in an extensive shallow ...

    Indian Academy of Sciences (India)

    Keywords. Methane emission; spatial and temporal variation; macro-algal zone; estuaries; Pulicat lake. Abstract. Sedimentary methane (CH4) fluxes and oxidation rates were determined over the wet and dry seasons (four measurement campaigns)in Pulicat lake,an extensive shallow estuary in south India. Dissolved CH4 ...

  2. The small-scale spatial distribution of an invading moth

    DEFF Research Database (Denmark)

    Nash, David Richard; Agassiz, David J. L.; Godfray, H. C. J.

    1995-01-01

    , no spatial pattern in the order that bushes were infested was found. If the source of colonisation was a single or small group of infested plants within the site, there was some evidence that nearby plants were colonised first. We found no evidence of population turnover after colonisat- ion. We interpret...

  3. Toward Bayesian Inference of the Spatial Distribution of Proteins

    DEFF Research Database (Denmark)

    Hooghoudt, Jan Otto; Waagepetersen, Rasmus Plenge; Barroso, Margarida

    2017-01-01

    . In this paper we propose a new likelihood-based approach to statistical inference for FRET microscopic data. The likelihood function is obtained from a detailed modeling of the FRET data generating mechanism conditional on a protein configuration. We next follow a Bayesian approach and introduce a spatial point...

  4. Spatial random field models inspired from statistical physics with applications in the geosciences

    Science.gov (United States)

    Hristopulos, Dionissios T.

    2006-06-01

    The spatial structure of fluctuations in spatially inhomogeneous processes can be modeled in terms of Gibbs random fields. A local low energy estimator (LLEE) is proposed for the interpolation (prediction) of such processes at points where observations are not available. The LLEE approximates the spatial dependence of the data and the unknown values at the estimation points by low-lying excitations of a suitable energy functional. It is shown that the LLEE is a linear, unbiased, non-exact estimator. In addition, an expression for the uncertainty (standard deviation) of the estimate is derived.

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

    Science.gov (United States)

    Scherer, Laura; Pfister, Stephan

    2015-04-01

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

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

    African Journals Online (AJOL)

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

  7. Spatial distribution of stink bugs (hemiptera: pentatomidae) in wheat.

    Science.gov (United States)

    Reay-Jones, Francis P F

    2014-01-01

    A two-year study was conducted in South Carolina wheat (Triticum aestivum L. (Poales: Poaceae)) fields to describe spatial and temporal dynamics of stink bugs (Hemiptera: Pentatomidae), which were sampled weekly with sweep nets. In 2010, the main phytophagous stink bugs caught in a grid sampling plan across two fields were the brown stink bug, Euschistus servus (Say), the rice stink bug, Oebalus pugnax (F.), the southern green stink bug, Nezara viridula (L.), and the red shouldered stink bug, Thyanta custator (F.), for both adults and nymphs. In 2011, the main phytophagous stink bugs were E. servus, O. pugnax, N. viridula, and T. custator across two fields. Adult stink bug counts adjacent to fallow fields were 2.1-fold greater for all species combined compared with counts adjacent to woods. Spatial Analysis by Distance IndicEs (SADIE) indicated significant aggregation for 35% of analyses for adults and nymph stink bugs at each sampling date. As a measure of spatial and temporal stability, positive SADIE association indices among sampling dates recorded 11, 36, 43, and 16% of analyses for adult E. servus and 7, 50, 50, and 14% for adult O. pugnax in fields A, B, C, and D, respectively. Adult and nymph stink bugs were spatially associated within wheat fields based on SADIE association indices. Seasonal counts of stink bugs were spatially associated with spike counts at least once for each species across the four fields. Future work may investigate practices to reduce stink bug buildup on wheat in the spring and movement to susceptible crops such as corn, Zea mays L.

  8. 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

    2011-01-01

    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. PMID:21444779

  9. 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.

  10. 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......Stress can affect the brain functionality in many ways. As the synaptic vesicles have a major role in nervous signal transportation in synapses, their distribution in relationship to the active zone is very important in studying the neuron responses. We study the effect of stress on brain...... 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....

  11. Spatially-Distributed Cost–Effectiveness Analysis Framework to Control Phosphorus from Agricultural Diffuse Pollution

    Science.gov (United States)

    Geng, Runzhe; Wang, Xiaoyan; Sharpley, Andrew N.; Meng, Fande

    2015-01-01

    Best management practices (BMPs) for agricultural diffuse pollution control are implemented at the field or small-watershed scale. However, the benefits of BMP implementation on receiving water quality at multiple spatial is an ongoing challenge. In this paper, we introduce an integrated approach that combines risk assessment (i.e., Phosphorus (P) index), model simulation techniques (Hydrological Simulation Program–FORTRAN), and a BMP placement tool at various scales to identify the optimal location for implementing multiple BMPs and estimate BMP effectiveness after implementation. A statistically significant decrease in nutrient discharge from watersheds is proposed to evaluate the effectiveness of BMPs, strategically targeted within watersheds. Specifically, we estimate two types of cost-effectiveness curves (total pollution reduction and proportion of watersheds improved) for four allocation approaches. Selection of a ‘‘best approach” depends on the relative importance of the two types of effectiveness, which involves a value judgment based on the random/aggregated degree of BMP distribution among and within sub-watersheds. A statistical optimization framework is developed and evaluated in Chaohe River Watershed located in the northern mountain area of Beijing. Results show that BMP implementation significantly (p >0.001) decrease P loss from the watershed. Remedial strategies where BMPs were targeted to areas of high risk of P loss, deceased P loads compared with strategies where BMPs were randomly located across watersheds. Sensitivity analysis indicated that aggregated BMP placement in particular watershed is the most cost-effective scenario to decrease P loss. The optimization approach outlined in this paper is a spatially hierarchical method for targeting nonpoint source controls across a range of scales from field to farm, to watersheds, to regions. Further, model estimates showed targeting at multiple scales is necessary to optimize program

  12. Spatially-Distributed Cost-Effectiveness Analysis Framework to Control Phosphorus from Agricultural Diffuse Pollution.

    Science.gov (United States)

    Geng, Runzhe; Wang, Xiaoyan; Sharpley, Andrew N; Meng, Fande

    2015-01-01

    Best management practices (BMPs) for agricultural diffuse pollution control are implemented at the field or small-watershed scale. However, the benefits of BMP implementation on receiving water quality at multiple spatial is an ongoing challenge. In this paper, we introduce an integrated approach that combines risk assessment (i.e., Phosphorus (P) index), model simulation techniques (Hydrological Simulation Program-FORTRAN), and a BMP placement tool at various scales to identify the optimal location for implementing multiple BMPs and estimate BMP effectiveness after implementation. A statistically significant decrease in nutrient discharge from watersheds is proposed to evaluate the effectiveness of BMPs, strategically targeted within watersheds. Specifically, we estimate two types of cost-effectiveness curves (total pollution reduction and proportion of watersheds improved) for four allocation approaches. Selection of a ''best approach" depends on the relative importance of the two types of effectiveness, which involves a value judgment based on the random/aggregated degree of BMP distribution among and within sub-watersheds. A statistical optimization framework is developed and evaluated in Chaohe River Watershed located in the northern mountain area of Beijing. Results show that BMP implementation significantly (p >0.001) decrease P loss from the watershed. Remedial strategies where BMPs were targeted to areas of high risk of P loss, deceased P loads compared with strategies where BMPs were randomly located across watersheds. Sensitivity analysis indicated that aggregated BMP placement in particular watershed is the most cost-effective scenario to decrease P loss. The optimization approach outlined in this paper is a spatially hierarchical method for targeting nonpoint source controls across a range of scales from field to farm, to watersheds, to regions. Further, model estimates showed targeting at multiple scales is necessary to optimize program efficiency

  13. Spatially-Distributed Cost-Effectiveness Analysis Framework to Control Phosphorus from Agricultural Diffuse Pollution.

    Directory of Open Access Journals (Sweden)

    Runzhe Geng

    Full Text Available Best management practices (BMPs for agricultural diffuse pollution control are implemented at the field or small-watershed scale. However, the benefits of BMP implementation on receiving water quality at multiple spatial is an ongoing challenge. In this paper, we introduce an integrated approach that combines risk assessment (i.e., Phosphorus (P index, model simulation techniques (Hydrological Simulation Program-FORTRAN, and a BMP placement tool at various scales to identify the optimal location for implementing multiple BMPs and estimate BMP effectiveness after implementation. A statistically significant decrease in nutrient discharge from watersheds is proposed to evaluate the effectiveness of BMPs, strategically targeted within watersheds. Specifically, we estimate two types of cost-effectiveness curves (total pollution reduction and proportion of watersheds improved for four allocation approaches. Selection of a ''best approach" depends on the relative importance of the two types of effectiveness, which involves a value judgment based on the random/aggregated degree of BMP distribution among and within sub-watersheds. A statistical optimization framework is developed and evaluated in Chaohe River Watershed located in the northern mountain area of Beijing. Results show that BMP implementation significantly (p >0.001 decrease P loss from the watershed. Remedial strategies where BMPs were targeted to areas of high risk of P loss, deceased P loads compared with strategies where BMPs were randomly located across watersheds. Sensitivity analysis indicated that aggregated BMP placement in particular watershed is the most cost-effective scenario to decrease P loss. The optimization approach outlined in this paper is a spatially hierarchical method for targeting nonpoint source controls across a range of scales from field to farm, to watersheds, to regions. Further, model estimates showed targeting at multiple scales is necessary to optimize program

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

    Science.gov (United States)

    McKinnon, Alan C.

    1984-01-01

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

  15. [Spatial distribution patterns of adult population of Pseudorobitis gibbus (Coleoptera: Apionidae) in Taixing Garden, Tai'an, Shandong, China].

    Science.gov (United States)

    Li, Yan; Zheng, Fang-Qiang; Yu, Li-Ying; Qiao, Lu-Qin; Lu, Xi-Ping

    2014-01-01

    The vertical and horizontal distributions of Pseudorobitis gibbus adults on Lagerstroemia indica were analyzed by using the aggregation indices and geostatistics. The results from aggregation index methods indicated that its vertical distribution was an aggregated distribution, and the aggregation average (lambda) was above two, showing that the aggregation resulted from its bionomics and behaviors, not from the environmental factors. The results of geostatistic analysis showed that the best fitting models for the five different sampling data in June 4, June 16, June 29, July 25 and August 22 were Gaussian, Gaussian, Linear, Gaussian and Linear models, respectively, but random models in July 12 and August 7. It was concluded that the horizontal distribution of the pest was aggregated on the whole, and there existed a spatial correlation ranging from 1.68 to 9.79 m on the different dates.

  16. 447 A Spatial Analysis of Population Distribution and Housing Patterns

    African Journals Online (AJOL)

    User

    total of 200 questionnaires were administered using the stratified random sampling technique. The study area ... services and amenities and facilities such as portable water supply, energy supply, adequate toilet, kitchen, ... concentration of the housing problems in urban areas, where “overcrowding and high rents slum and ...

  17. Spatial and temporal distribution of phytoplankton in Lake Skadar

    Directory of Open Access Journals (Sweden)

    Rakočević Jelena

    2012-01-01

    Full Text Available Phytoplankton seasonal succession and spatial heterogeneity were studied in Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal divisions were observed, with Bacillariophyta being best represented (52.8%. The general pattern of phytoplankton seasonal succession in Lake Skadar was: Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and winter. Distinct spatial heterogeneity was observed. The central, open part of the lake (pelagic zone was characterized by dominant euplanktonic species, mostly diatoms, whereas the western and northwestern parts (more isolated and shallower had higher abundance of greens and blue-greens and a higher percentage of resuspended benthic-epiphytic forms in the phytoplankton community. Comparison with former phytoplankton data showed distinct differences in terms of the qualitative and quantitative composition of the phytoplankton community of Lake Skadar, which indicates lake deterioration.

  18. 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

  19. Predicting future spatial distribution of SOC across entire France

    Science.gov (United States)

    Meersmans, Jeroen; Van Rompaey, Anton; Quine, Tim; Martin, Manuel; Pagé, Christian; Arrouays, Dominique

    2013-04-01

    Soil organic carbon (SOC) is widely recognized as a key factor controlling soil quality and as a crucial and active component of the global C-cycle. Hence, there exists a growing interest in monitoring and modeling the spatial and temporal behavior of this pool. So far, a large attempt has been made to map SOC at national scales for current and/or past situations. Despite some coarse predictions, detailed spatial SOC predictions for the future are still lacking. In this study we aim to predict future spatial evolution of SOC driven by climate and land use change for France up to the year 2100. Therefore, we combined 1) an existing model, predicting SOC as a function of soil type, climate, land use and management (Meersmans et al 2012), with 2) eight different IPCC spatial explicit climate change predictions (conducted by CERFACS) and 3) Land use change scenario predictions. We created business-as-usual land use change scenarios by extrapolating observed trends and calibrating logistic regression models, incorporating a large set of physical and socio-economic factors, at the regional level in combination with a multi-objective land allocation (MOLA) procedure. The resultant detailed projections of future SOC evolution across all regions of France, allow us to identify regions that are most likely to be characterized by a significant gain or loss of SOC and the degree to which land use decisions/outcomes control the scale of loss and gain. Therefore, this methodology and resulting maps can be considered as powerful tools to aid decision making concerning appropriate soil management, in order to enlarge SOC storage possibilities and reduce soil related CO2 fluxes.

  20. Spatial Distribution of Stink Bugs (Hemiptera: Pentatomidae) in Wheat

    OpenAIRE

    Reay-Jones, Francis P. F.

    2014-01-01

    A two-year study was conducted in South Carolina wheat (Triticum aestivum L. (Poales: Poaceae)) fields to describe spatial and temporal dynamics of stink bugs (Hemiptera: Pentatomidae), which were sampled weekly with sweep nets. In 2010, the main phytophagous stink bugs caught in a grid sampling plan across two fields were the brown stink bug, Euschistus servus (Say), the rice stink bug, Oebalus pugnax (F.), the southern green stink bug, Nezara viridula (L.), and the red shouldered stink bug,...

  1. 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.

  2. Fitting and Analyzing Randomly Censored Geometric Extreme Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Muhammad Yameen Danish

    2016-06-01

    Full Text Available The paper presents the Bayesian analysis of two-parameter geometric extreme exponential distribution with randomly censored data. The continuous conjugate prior of the scale and shape parameters of the model does not exist while computing the Bayes estimates, it is assumed that the scale and shape parameters have independent gamma priors. It is seen that the closed-form expressions for the Bayes estimators are not possible; we suggest the Lindley’s approximation to obtain the Bayes estimates. However, the Bayesian credible intervals cannot be constructed while using this method, we propose Gibbs sampling to obtain the Bayes estimates and also to construct the Bayesian credible intervals. Monte Carlo simulation study is carried out to observe the behavior of the Bayes estimators and also to compare with the maximum likelihood estimators. One real data analysis is performed for illustration.

  3. The rising power of random distributed feedback fiber laser

    Science.gov (United States)

    Zhou, Pu; Ye, Jun; Xu, Jiangming; Zhang, Hanwei; Huang, Long; Wu, Jian; Xiao, Hu; Leng, Jinyong

    2018-01-01

    Random distributed feedback fiber lasers (RDFFL) are now attracting more and more attentions for their unique cavity-free, mode-free and structural simplicity features and broadband application potentials in many fields, such as long distance sensing, speck free imaging, nonlinear frequency conversion as well as new pump source. In this talk, we will review the recent research progresses on high power RDFFLs. We have achieved (1) More than 400 W RDFFL with nearly Gaussian beam profile based on crucial employment of fiber mismatching architecture. (2) High power RDFFL with specialized optical property that include: high power narrow-band RDFFL, hundred-watt level linearly-polarized RDFFL, hundred-watt level high-order RDFFL. (3) Power enhancements of RDFFL to record kilowatt level are demonstrated with the aid of fiber master oscillator power amplifier (MOPA) with different pump schemes.

  4. A new distributed computing model of mobile spatial information service grid based on mobile agent

    Science.gov (United States)

    Tian, Gen; Liu, Miao-long

    2009-10-01

    A new distributed computing model of mobile spatial information service is studied based on grid computing environment. Key technologies are presented in the model, including mobile agent (MA) distributed computing, grid computing, spatial data model, location based service (LBS), global positioning system (GPS), code division multiple access (CDMA), transfer control protocol/internet protocol (TCP/IP), and user datagram protocol (UDP). In order to deal with the narrow bandwidth and instability of the wireless internet, distributed organization of tremendous spatial data, limited processing speed and low memory of mobile devices, a new mobile agent based mobile spatial information service grid (MSISG) architecture is further proposed that has good load balance, high processing efficiency, less network communication and thus suitable for mobile distributed computing environment. It can provide applications of spatial information distributed computing and mobile service. The theories and technologies architecture of MSISG are built originally from the base, including spatial information mobile agent model, distributed grid geographic information system (GIS) server model, mobile agent server model and mobile GIS client model. An application system for MSISG is therefore developed authorship by visual c++ and embedded visual c++. A field test is carried out through this system in Shanghai, and the results show that the proposed model and methods are feasible and adaptable for mobile spatial information service.

  5. Spatial distribution of marine debris on the seafloor of Moroccan waters.

    Science.gov (United States)

    Loulad, S; Houssa, R; Rhinane, H; Boumaaz, A; Benazzouz, A

    2017-11-15

    Marine debris pollution is considered as a worldwide problem and a direct threat to the environment, economy and human health. In this paper, we provide the first quantitative assessment of debris on the seafloor of the southern part of the economic exclusive waters of Morocco. The data were collected in a scientific trawl survey carried out from 5 to 25 October 2014 between (26N) to (21N) covering different stratums of depths (from 10 to 266m) and following a sampling network of 100 stations distributed randomly in the study area. A total of 603kg of debris was collected and sorted into five main categories: plastic, metal, rubber, textiles and glass. Over 50% of collected items was made by plastic, 94% of them are the plastic fishing gear used to capture the Octopus vulgaris. The analysis of the distribution shows that anthropogenic debris is present in the majority of the prospected area (∼ 47,541km 2 ) with different densities ranging from 0 to 1768 (± 298,15)kg/km 2 . The spatial autocorrelation approach using GIS shows that the concentration of this debris is correlated very well with a set of factors such as the proximity to fishing activity sites. Moreover, the mechanism of transportation and dispersion was influenced by the hydrodynamic properties of the region. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Low LET proton microbeam to understand high-LET RBE by shaping spatial dose distribution

    Science.gov (United States)

    Greubel, Christoph; Ilicic, Katarina; Rösch, Thomas; Reindl, Judith; Siebenwirth, Christian; Moser, Marcus; Girst, Stefanie; Walsh, Dietrich W. M.; Schmid, Thomas E.; Dollinger, Günther

    2017-08-01

    High LET radiation, like heavy ions, are known to have a higher biological effectiveness (RBE) compared to low LET radiation, like X- or γ -rays. Theories and models attribute these higher effectiveness mostly to their extremely inhomogeneous dose deposition, which is concentrated in only a few micron sized spots. At the ion microprobe SNAKE, low LET 20 MeV protons (LET in water of 2.6 keV/μm) can be applied to cells either randomly distributed or focused to submicron spots, approximating heavy ion dose deposition. Thus, the transition between low and high LET energy deposition is experimentally accessible and the effect of different spatial dose distributions can be analysed. Here, we report on the technical setup to cultivate and irradiate 104 cells with submicron spots of low LET protons to measure cell survival in unstained cells. In addition we have taken special care to characterise the beam spot of the 20 MeV proton microbeam with fluorescent nuclear track detectors.

  7. Computational Analysis of the Spatial Distribution of Pre-Christian Slavic Sacred Sites

    Directory of Open Access Journals (Sweden)

    Anđelko Đermek

    2012-06-01

    Full Text Available This paper proposes a method to find out the units of length used by the Slavs prior to their Christianization. The method relies on a previous research of the tripartite structure of pre-Christian Slavic sacred sites discovered by Andrej Pleterski. Such spatial structures represent myth in space and are in correlation with the central Slavic myth of the divine battle between Perun and Veles as presented by Radoslav Katičić. By measuring the angles which Sun takes through the year cycle and comparing them with the angles between the sacred sites, the pagan priests had means to accurately determine the days of religious festivals and the calendar in general. The angles likely had an important role, but this article tries to examine weather the absolute values of the distance between the sacred sites were also important. The method relies on the mathematical properties of arithmetic and geometric sequences. If for some of the inital parameters of the sequences the probability function for a given distribution of sacred sites in some area shows to be significantly smaller than the average, then it is an indication that the respective distribution is not random. The parameters in such case may point to the system of measures used during the creation of the structure. The proposed method really detected some common modules, but in this phase it is only experimental and still can not be used as a proof of common Pan-Slavic system of units.

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

    Directory of Open Access Journals (Sweden)

    Arriaga–Flores, J. C.

    2018-01-01

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

  9. 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.

  10. Spatial distributions of red blood cells significantly alter local haemodynamics.

    Directory of Open Access Journals (Sweden)

    Joseph M Sherwood

    Full Text Available Although bulk changes in red blood cell concentration between vessels have been well characterised, local distributions are generally overlooked. Red blood cells aggregate, deform and migrate within vessels, forming heterogeneous distributions which have considerable effect on local haemodynamics. The present study reports data on the local distribution of human red blood cells in a sequentially bifurcating microchannel, representing the branching geometry of the microvasculature. Imaging methodologies with simple extrapolations are used to infer three dimensional, time-averaged velocity and haematocrit distributions under a range of flow conditions. Strong correlation between the bluntness of the velocity and haematocrit profiles in the parent branch of the geometry is observed and red blood cell aggregation has a notable effect on the observed trends. The two branches of the first bifurcation show similar characteristics in terms of the shapes of the profiles and the extent of plasma skimming, despite the difference in geometric configuration. In the second bifurcation, considerable asymmetry between the branches in the plasma skimming relationship is observed, and elucidated by considering individual haematocrit profiles. The results of the study highlight the importance of considering local haematocrit distributions in the analysis of blood flow and could lead to more accurate computational models of blood flow in microvascular networks. The experimental approaches developed in this work provide a foundation for further examining the characteristics of microhaemodynamics.

  11. Spatial Distribution and Minimum Sample Size for Overwintering Larvae of the Rice Stem Borer Chilo suppressalis (Walker) in Paddy Fields.

    Science.gov (United States)

    Arbab, A

    2014-10-01

    The rice stem borer, Chilo suppressalis (Walker), feeds almost exclusively in paddy fields in most regions of the world. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling procedures, and adopting precise agricultural techniques. Field experiments were conducted during 2011 and 2012 to estimate the spatial distribution pattern of the overwintering larvae. Data were analyzed using five distribution indices and two regression models (Taylor and Iwao). All of the indices and Taylor's model indicated random spatial distribution pattern of the rice stem borer overwintering larvae. Iwao's patchiness regression was inappropriate for our data as shown by the non-homogeneity of variance, whereas Taylor's power law fitted the data well. The coefficients of Taylor's power law for a combined 2 years of data were a = -0.1118, b = 0.9202 ± 0.02, and r (2) = 96.81. Taylor's power law parameters were used to compute minimum sample size needed to estimate populations at three fixed precision levels, 5, 10, and 25% at 0.05 probabilities. Results based on this equation parameters suggesting that minimum sample sizes needed for a precision level of 0.25 were 74 and 20 rice stubble for rice stem borer larvae when the average larvae is near 0.10 and 0.20 larvae per rice stubble, respectively.

  12. Probability distribution of intersymbol distances in random symbolic sequences: Applications to improving detection of keywords in texts and of amino acid clustering in proteins.

    Science.gov (United States)

    Carpena, Pedro; Bernaola-Galván, Pedro A; Carretero-Campos, Concepción; Coronado, Ana V

    2016-11-01

    Symbolic sequences have been extensively investigated in the past few years within the framework of statistical physics. Paradigmatic examples of such sequences are written texts, and deoxyribonucleic acid (DNA) and protein sequences. In these examples, the spatial distribution of a given symbol (a word, a DNA motif, an amino acid) is a key property usually related to the symbol importance in the sequence: The more uneven and far from random the symbol distribution, the higher the relevance of the symbol to the sequence. Thus, many techniques of analysis measure in some way the deviation of the symbol spatial distribution with respect to the random expectation. The problem is then to know the spatial distribution corresponding to randomness, which is typically considered to be either the geometric or the exponential distribution. However, these distributions are only valid for very large symbolic sequences and for many occurrences of the analyzed symbol. Here, we obtain analytically the exact, randomly expected spatial distribution valid for any sequence length and any symbol frequency, and we study its main properties. The knowledge of the distribution allows us to define a measure able to properly quantify the deviation from randomness of the symbol distribution, especially for short sequences and low symbol frequency. We apply the measure to the problem of keyword detection in written texts and to study amino acid clustering in protein sequences. In texts, we show how the results improve with respect to previous methods when short texts are analyzed. In proteins, which are typically short, we show how the measure quantifies unambiguously the amino acid clustering and characterize its spatial distribution.

  13. 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.

  14. Microscale spatial distributions of microbes and viruses in intertidal photosynthetic microbial mats

    NARCIS (Netherlands)

    Carreira, C; Piel, T; Staal, M.; Stuut, J.-B; Middelboe, M.; Brussaard, C.P.D.

    2015-01-01

    Intertidal photosynthetic microbial mats from the Wadden Sea island Schiermonnikoog were examined for microscale (millimetre) spatial distributions of viruses, prokaryotes and oxygenic photoautotrophs (filamentous cyanobacteria and benthic diatoms) at different times of the year. Abundances of

  15. The contributions of resource availability and social forces to foraging distributions : a spatial lag modelling approach

    NARCIS (Netherlands)

    Folmer, Eelke O.; Piersma, Theunis

    2012-01-01

    The spatial distribution of foraging animals at a given time simultaneously depends on (1) exogenous environmental variables such as resource availability and abiotic habitat characteristics, and (2) the endogenous variable social aggregation made up of the opposing mechanisms of conspecific

  16. The contributions of resource availability and social forces to foraging distributions: a spatial lag modelling approach

    NARCIS (Netherlands)

    Folmer, E.O.; Piersma, T.

    2012-01-01

    The spatial distribution of foraging animals at a given time simultaneously depends on (1) exogenous environmental variables such as resource availability and abiotic habitat characteristics, and (2) the endogenous variable social aggregation made up of the opposing mechanisms of conspecific

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

    Science.gov (United States)

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

    2016-01-01

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

  18. 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 ...

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

    OpenAIRE

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

    2014-01-01

    Brain activity during rest is spatially coherent over functional connectivity networks called resting-state networks. In resting-state functional magnetic resonance imaging, independent component analysis yields spatially distributed network representations reflecting distinct mental processes, such as intrinsic (default) or extrinsic (executive) attention, and sensory inhibition or excitation. These aspects can be related to different treatments or subjective experiences. Among these, exhaus...

  20. 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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    be imprecise for species with low densities or few observations. Additionally, simple geostatistical methods fail to account for correlations in distribution among species and generally estimate such cross-correlations as a post hoc exercise. 2. We therefore present spatial factor analysis (SFA), a spatial...

  2. 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...

  3. Spatial distribution of Batrachochytrium dendrobatidis in South American caecilians.

    Science.gov (United States)

    Lambertini, Carolina; Becker, C Guilherme; Bardier, Cecilia; da Silva Leite, Domingos; Toledo, Luís Felipe

    2017-04-20

    The amphibian-killing fungus Batrachochytrium dendrobatidis (Bd) is linked to population declines in anurans and salamanders globally. To date, however, few studies have attempted to screen Bd in live caecilians; Bd-positive caecilians have only been reported in Africa and French Guiana. Here, we performed a retrospective survey of museum preserved specimens to (1) describe spatial patterns of Bd infection in Gymnophiona across South America and (2) test whether areas of low climatic suitability for Bd in anurans predict Bd spatial epidemiology in caecilians. We used quantitative PCR to detect Bd in preserved caecilians collected over a 109 yr period, and performed autologistic regressions to test the effect of bioclimatic metrics of temperature and precipitation, vegetation density, and elevation on the likelihood of Bd occurrence. We detected an overall Bd prevalence of 12.4%, with positive samples spanning the Uruguayan savanna, Brazil's Atlantic Forest, and the Amazon basin. Our autologistic models detected a strong effect of macroclimate, a weaker effect of vegetation density, and no effect of elevation on the likelihood of Bd occurrence. Although most of our Bd-positive records overlapped with reported areas of high climatic suitability for the fungus in the Neotropics, many of our new Bd-positive samples extend far into areas of poor suitability for Bd in anurans. Our results highlight an important gap in the study of amphibian chytridiomycosis: the potential negative impact of Bd on Neotropical caecilians and the hypothetical role of caecilians as Bd reservoirs.

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

    Science.gov (United States)

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

    2013-12-01

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

  5. Sex ratio and spatial distribution of male and female Antennaria dioica (Asteraceae) plants

    OpenAIRE

    Varga, Sandra; Kytöviita, Minna-Maarit

    2011-01-01

    Sex ratio, sex spatial distribution and sexual dimorphism in reproduction and arbuscular mycorrhizal colonisation were investigated in the dioecious clonal plant Antennaria dioica (Asteraceae). Plants were monitored for five consecutive years in six study plots in Oulanka, northern Finland. Sex ratio, spatial distribution of sexes, flowering frequency, number of floral shoots and the number and weight of inflorescences were recorded. In addition, intensity of mycorrhizal fungi in the roots wa...

  6. The behavior of solutions of an equation with a large spatially distributed control

    Science.gov (United States)

    Kashchenko, I.

    2017-12-01

    The paper is devoted to the dynamical properties of the scalar complex equation and system of two equations with spatially distributed parameters. Main assumption is that the coefficient of spatial distribution is sufficiently large. Using asymptotic methods we construct the families of special parabolic equations, which do not contain big and small parameters, which nonlocal dynamics determines the behaviour of solutions of the original equation.

  7. Compressive Feedback Control Design for Spatially Distributed Systems

    Science.gov (United States)

    2017-01-03

    availability or distribution limitations of the report. If additional limitations/ restrictions or special markings are indicated, follow agency...performance measure. Two efficient polynomial-time approximation algorithms are de - vised to tackle this network synthesis problem: a linearization...Catalyzing Enzymes Allosteric Regulation Autocatalysis Cell Consumption of ATP Figure 3: Schematic diagram of glycolysis pathway. Early experimental

  8. Spatial Analysis of Particle Size Distribution of Soils Formed on ...

    African Journals Online (AJOL)

    ... and silt and silt clay ratio (r = 0.77, p<0.01). It was observed that clay, sand and silt + clay bear similar distribution in the field as shown by the prediction contour maps. These variables could receive similar treatment in precision farming, enhance knowledge of pedogenesis and sustainable environmental management.

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

    African Journals Online (AJOL)

    Such spaces have consequently failed to fulfill the roles ascribed to them and instead have become neglected and unsafe to operate in. Space syntax and structured observation have been used to collect data. Multiple regression analysis establishes that nine public space variables significantly predict the distribution of ...

  10. Forage potential, micro-spatial and temporal distribution of ground ...

    African Journals Online (AJOL)

    Despite the critical roles played by arthropods in ecosystem functioning and nutrient cycling, a general lack of information about the ecology of many arthropods in West African coastal wetlands persists. An investigation into the abundance, distribution and forage potential of ground arthropods to waterbirds inaWest African ...

  11. Spatial Distribution of Wildebeest in Serengeti National Park, Tanzania

    African Journals Online (AJOL)

    Serengeti wildebeest Connochaetes taurinus often come in contact with human activities which together with population growth, climate change and poverty tend to regulate wildebeest population. Since wildebeest distribution in relation to natural and man made changes is poorly understood, I examined ten GPS collared ...

  12. Spatial distribution of soil contaminated with Toxoplasma gondii oocysts in relation to the distribution and use of domestic cat defecation sites on dairy farms.

    Science.gov (United States)

    Simon, J A; Kurdzielewicz, S; Jeanniot, E; Dupuis, E; Marnef, F; Aubert, D; Villena, I; Poulle, M-L

    2017-05-01

    Little information is available on the relationship between the spatial distribution of zoonotic parasites in soil and the pattern of hosts' faeces deposition at a local scale. In this study, the spatial distribution of soil contaminated by the parasite Toxoplasma gondii was investigated in relation to the distribution and use of the defecation sites of its definitive host, the domestic cat (Felis catus). The study was conducted on six dairy farms with a high number of cats (seven to 30 cats). During regular visits to the farms over a 10month period, the cat population and cat defecation sites (latrines and sites of scattered faeces) on each farm were systematically surveyed. During the last visit, 561 soil samples were collected from defecation sites and random points, and these samples were searched for T. gondii DNA using real-time quantitative PCR. Depending on the farm, T. gondii DNA was detected in 37.7-66.3% of the soil samples. The proportion of contaminated samples at a farm was positively correlated with the rate of new cat latrines replacing former cat latrines, suggesting that inconstancy in use of a latrine by cats affects the distribution of T. gondii in soil. On the farms, known cat defecation sites were significantly more often contaminated than random points, but 25-62.5% of the latter were also found to be contaminated. Lastly, the proportion of positive T. gondii samples in latrines was related to the proximity of the cats' main feeding and resting sites on the farms. This study demonstrates that T. gondii can be widely distributed in farm soil despite the heterogeneous distribution of cat faeces. This supports the hypothesis that farms are hotspot areas for the risk of T. gondii oocyst-induced infection in rural environments. Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

  13. Smoothing effect for spatially distributed renewable resources and its impact on power grid robustness

    CERN Document Server

    Nagata, Motoki; Fujiwara, Naoya; Tanaka, Gouhei; Suzuki, Hideyuki; Aihara, Kazuyuki

    2015-01-01

    In this paper, we show that spatial correlation of renewable energy outputs greatly influences the robustness of power grids. First, we propose a new index for the spatial correlation among renewable energy outputs. We find that the spatial correlation of renewable energy outputs in a short time-scale is as weak as that caused by independent random variables and that in a long time-scale is as strong as that under perfect synchronization. Then, by employing the topology of the power grid in eastern Japan, we analyze the robustness of the power grid with spatial correlation of renewable energy outputs. The analysis is performed by using a realistic differential-algebraic equations model and the result shows that the spatial correlation of the energy resources strongly degrades the robustness of the power grid. Our result suggests that the spatial correlation of the renewable energy outputs should be taken into account when estimating the stability of power grids.

  14. 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

  15. Simulating the large-scale spatial sand-mud distribution in a schematized process-based tidal inlet system model

    NARCIS (Netherlands)

    Scheel, F.; van Ledden, M.; van Prooijen, B.C.; Stive, M.J.F.

    2012-01-01

    Tidal basins, as found in the Dutch Wadden Sea, are characterized by strong spatial variations in bathymetry and sediment distribution. In this contribution, the aim is at simulating the spatial sand-mud distribution of a tidal basin. Predicting this spatial distribution is however complicated, due

  16. 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

  17. Cartograms tool to represent spatial uncertainty in species distribution

    Directory of Open Access Journals (Sweden)

    Duccio Rocchini

    2017-02-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

  19. Strong neutral spatial effects shape tree species distributions across life stages at multiple scales.

    Directory of Open Access Journals (Sweden)

    Yue-Hua Hu

    Full Text Available Traditionally, ecologists use lattice (regional summary count data to simulate tree species distributions to explore species coexistence. However, no previous study has explicitly compared the difference between using lattice count and basal area data and analyzed species distributions at both individual species and community levels while simultaneously considering the combined scenarios of life stage and scale. In this study, we hypothesized that basal area data are more closely related to environmental variables than are count data because of strong environmental filtering effects. We also address the contribution of niche and the neutral (i.e., solely dependent on distance factors to species distributions. Specifically, we separately modeled count data and basal area data while considering life stage and scale effects at the two levels with simultaneous autoregressive models and variation partitioning. A principal coordinates of neighbor matrix (PCNM was used to model neutral spatial effects at the community level. The explained variations of species distribution data did not differ significantly between the two types of data at either the individual species level or the community level, indicating that the two types of data can be used nearly identically to model species distributions. Neutral spatial effects represented by spatial autoregressive parameters and the PCNM eigenfunctions drove species distributions on multiple scales, different life stages and individual species and community levels in this plot. We concluded that strong neutral spatial effects are the principal mechanisms underlying the species distributions and thus shape biodiversity spatial patterns.

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

    DEFF Research Database (Denmark)

    Lewy, Peter; Kristensen, Kasper

    2009-01-01

    The spatial distribution of cod (Gadus morhua) in the North Sea and the Skagerrak was analysed over a 24-year period using the Log Gaussian Cox Process (LGCP). In contrast to other spatial models of the distribution of fish, LGCP avoids problems with zero observations and includes the spatial cor...... was found to be constant or declining in the period. This means that cod does not follow the theory of density-dependent habitat selection, as the concentration of the stock does not increase when stock abundance decreases....

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

    Science.gov (United States)

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

    2016-09-01

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

  2. Time-resolved spatial distribution of Balmer alpha line radiation from magnetoplasma compressor

    Science.gov (United States)

    Dojčinović, I. P.; Kuraica, M. M.; Astashynski, V. M.; Cvetanović, N.; Purić, J.

    2002-12-01

    This paper deals with time and spatial resolved spectroscopy of hydrogen Balmer alpha line radiation from MPC plasma. Plasma was observed with a set of 10 optical fibers distributed along z axis starting from the outlet of the cathode with 7 mm separation up to 6.3 cm distance. The radiation was analysed using HR320S spectrometer equipped with and IMACON 790 high speed camera system with appropriated CCD camera for detection. From the registered time and spatially resolved Balmer line images, the Stark profiles of Hα lines were obtained and from them temporal and spatial electron density distribution of MPC plasma was determined.

  3. Spatial Distribution of Esca Symptomatic Plants in Dão Vineyards (Centre Portugal and Isolation of Associated Fungi

    Directory of Open Access Journals (Sweden)

    J. Sofia

    2006-04-01

    Full Text Available During three years, from 2002 to 2004, a vineyard was surveyed for esca incidence and spatial distribution of deceased/symptomatic vines. Individual plants were recorded as diseased when characteristic esca symptoms were visible in summer surveys or in winter surveys. Some of the symptomatic vines were uprooted every year and fungi most commonly isolated from those plants were listed. Two dimensional maps referring the presence/absence of diseased plants were drawn every year and a cumulative map was obtained on the last year of the survey. Based on the former map, spatial distribution of esca symptomatic plants was analysed in order to confirm the null hypothesis of randomness on the disease spread. Our results showed that: i internal lesions of uprooted vines were classifiable in two main categories, according to the observed decays; ii with the exception of Eutypa lata, fungi commonly associated with esca were present in the uprooted vines; iii the number of esca symptomatic plants increased every year of the survey; iv esca foliar symptoms were discontinuous from year to year and v the distribution of infected vines on the plot was random.

  4. Modelling the spatial distribution of the nuisance mosquito species Anopheles plumbeus (Diptera: Culicidae) in the Netherlands.

    Science.gov (United States)

    Ibañez-Justicia, Adolfo; Cianci, Daniela

    2015-05-01

    Landscape modifications, urbanization or changes of use of rural-agricultural areas can create more favourable conditions for certain mosquito species and therefore indirectly cause nuisance problems for humans. This could potentially result in mosquito-borne disease outbreaks when the nuisance is caused by mosquito species that can transmit pathogens. Anopheles plumbeus is a nuisance mosquito species and a potential malaria vector. It is one of the most frequently observed species in the Netherlands. Information on the distribution of this species is essential for risk assessments. The purpose of the study was to investigate the potential spatial distribution of An. plumbeus in the Netherlands. Random forest models were used to link the occurrence and the abundance of An. plumbeus with environmental features and to produce distribution maps in the Netherlands. Mosquito data were collected using a cross-sectional study design in the Netherlands, from April to October 2010-2013. The environmental data were obtained from satellite imagery and weather stations. Statistical measures (accuracy for the occurrence model and mean squared error for the abundance model) were used to evaluate the models performance. The models were externally validated. The maps show that forested areas (centre of the Netherlands) and the east of the country were predicted as suitable for An. plumbeus. In particular high suitability and high abundance was predicted in the south-eastern provinces Limburg and North Brabant. Elevation, precipitation, day and night temperature and vegetation indices were important predictors for calculating the probability of occurrence for An. plumbeus. The probability of occurrence, vegetation indices and precipitation were important for predicting its abundance. The AUC value was 0.73 and the error in the validation was 0.29; the mean squared error value was 0.12. The areas identified by the model as suitable and with high abundance of An. plumbeus, are

  5. 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...

  6. 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

    Crop performance and weed suppression increase with increasing crop spatial uniformity. We use spatial pattern simulations and field experiments to show the current state-of-the-art for spatial uniformity for different seeding technologies. We use Morisita's Index to quantify how changes in row...... 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...

  7. A hybrid method for assessment of soil pollutants spatial distribution

    Science.gov (United States)

    Tarasov, D. A.; Medvedev, A. N.; Sergeev, A. P.; Shichkin, A. V.; Buevich, A. G.

    2017-07-01

    The authors propose a hybrid method to predict the distribution of topsoil pollutants (Cu and Cr). The method combines artificial neural networks and kriging. Corresponding computer models were built and tested on real data on example of subarctic regions of Russia. The network structure selection was based on the minimization of the Root-mean-square error between real and predicted concentrations. The constructed models show that the prognostic accuracy of the artificial neural network is higher than in case of the geostatistical (kriging) and deterministic methods. The conclusion is that hybridization of models (artificial neural network and kriging) provides the improvement of the total predictive accuracy.

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

    Directory of Open Access Journals (Sweden)

    E. Saar

    2005-09-01

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

  9. 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.

  10. Spatial distribution of soil organic carbon stock in Moso bamboo forests in subtropical China

    Science.gov (United States)

    Tang, Xiaolu; Xia, Mingpeng; Pérez-Cruzado, César; Guan, Fengying; Fan, Shaohui

    2017-02-01

    Moso bamboo (Phyllostachys heterocycla (Carr.) Mitford cv. Pubescens) is an important timber substitute in China. Site specific stand management requires an accurate estimate of soil organic carbon (SOC) stock for maintaining stand productivity and understanding global carbon cycling. This study compared ordinary kriging (OK) and inverse distance weighting (IDW) approaches to study the spatial distribution of SOC stock within 0-60 cm using 111 soil samples in Moso bamboo forests in subtropical China. Similar spatial patterns but different spatial distribution ranges of SOC stock from OK and IDW highlighted the necessity to apply different approaches to obtain accurate and consistent results of SOC stock distribution. Different spatial patterns of SOC stock suggested the use of different fertilization treatments in Moso bamboo forests across the study area. SOC pool within 0-60 cm was 6.46 and 6.22 Tg for OK and IDW; results which were lower than that of conventional approach (CA, 7.41 Tg). CA is not recommended unless coordinates of the sampling locations are missing and the spatial patterns of SOC stock are not required. OK is recommended for the uneven distribution of sampling locations. Our results can improve methodology selection for investigating spatial distribution of SOC stock in Moso bamboo forests.

  11. Three-dimensional distribution of random velocity inhomogeneities at the Nankai trough seismogenic zone

    Science.gov (United States)

    Takahashi, T.; Obana, K.; Yamamoto, Y.; Nakanishi, A.; Kaiho, Y.; Kodaira, S.; Kaneda, Y.

    2012-12-01

    The Nankai trough in southwestern Japan is a convergent margin where the Philippine sea plate is subducted beneath the Eurasian plate. There are major faults segments of huge earthquakes that are called Tokai, Tonankai and Nankai earthquakes. According to the earthquake occurrence history over the past hundreds years, we must expect various rupture patters such as simultaneous or nearly continuous ruptures of plural fault segments. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) conducted seismic surveys at Nankai trough in order to clarify mutual relations between seismic structures and fault segments, as a part of "Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes" funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. This study evaluated the spatial distribution of random velocity inhomogeneities from Hyuga-nada to Kii-channel by using velocity seismograms of small and moderate sized earthquakes. Random velocity inhomogeneities are estimated by the peak delay time analysis of S-wave envelopes (e.g., Takahashi et al. 2009). Peak delay time is defined as the time lag from the S-wave onset to its maximal amplitude arrival. This quantity mainly reflects the accumulated multiple forward scattering effect due to random inhomogeneities, and is quite insensitive to the inelastic attenuation. Peak delay times are measured from the rms envelopes of horizontal components at 4-8Hz, 8-16Hz and 16-32Hz. This study used the velocity seismograms that are recorded by 495 ocean bottom seismographs and 378 onshore seismic stations. Onshore stations are composed of the F-net and Hi-net stations that are maintained by National Research Institute for Earth Science and Disaster Prevention (NIED) of Japan. It is assumed that the random inhomogeneities are represented by the von Karman type PSDF. Preliminary result of inversion analysis shows that spectral gradient of PSDF (i.e., scale dependence of

  12. GIS AWARENESS FOR SURVEYORS – A SPATIAL DATA DISTRIBUTION PERSECTIVE

    Directory of Open Access Journals (Sweden)

    J.-H. Hong

    2012-09-01

    Full Text Available The rapid technological growth of GIS, internet and mobile devices has steered a variety of innovated and pioneering applications in the past few years. All of these applications require spatial data that meet specified criteria to ensure the quality of the service content. The traditional role for surveyors was to use surveying technology and instruments to determine the location of phenomena of interests and offer map products to serve as the basis for decision making. As the application demands becomes more variety and instantaneous, the role and responsibility for modern surveyors must be examined. Professional surveyors nowadays must have both the knowledge and skills to produce geospatial data that precisely meet the various application needs and correctly convey their understanding about data to domain users to avoid wrong decision making. This paper discussed how we include such considerations into our curriculum design at the Dept of Geomatics, NCKU. During their studies, students are expected to establish a correct understanding about the role and responsibility of surveyors and develop themselves to be "solution providers" for providing reliable geospatial data.

  13. 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

  14. Spatial distribution of livestock concentration areas and soil nutrients in pastures

    NARCIS (Netherlands)

    Sanderson, M.A.; Schmidt, J.; Feldmand, C.; Herrmann, A.

    2010-01-01

    Livestock concentration areas can be significant point sources of nutrient pollution. Our objective was to determine the spatial distribution of livestock concentration areas in pastures at the farm scale, along with the distribution of soil nutrients at the individual livestock concentration area

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

    African Journals Online (AJOL)

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

  16. The spatial distribution of large cometary meteoroids in the inner solar system

    Science.gov (United States)

    Mcbride, Neil; Hughes, David W.

    1992-01-01

    A model of the spatial density distribution of large (m greater than 10(exp -3) g) cometary meteoroids in the inner solar system is obtained assuming that they have orbits closely associated with that of their parent comet. Distributions of the orbital parameters of the Taurid, Quadrantid and Perseid meteoroid streams are used in developing the model.

  17. 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

  18. Spatial distribution of thermokarst terrain in Arctic Alaska

    Science.gov (United States)

    Farquharson, L. M.; Mann, D. H.; Grosse, G.; Jones, B. M.; Romanovsky, V. E.

    2016-11-01

    In landscapes underlain by ice-rich permafrost, the development of thermokarst landforms can have drastic impacts on ecosystem processes and human infrastructure. Here we describe the distribution of thermokarst landforms in the continuous permafrost zone of Arctic Alaska, analyze linkages to the underlying surficial geology, and discuss the vulnerability of different types of landscapes to future thaw. We identified nine major thermokarst landforms and then mapped their distributions in twelve representative study areas totaling 300-km2. These study areas differ in their geologic history, permafrost-ice content, and ground thermal regime. Results show that 63% of the entire study area is occupied by thermokarst landforms and that the distribution of thermokarst landforms and overall landscape complexity varies markedly with surficial geology. Areas underlain by ice-rich marine silt are the most affected by thermokarst (97% of total area), whereas areas underlain by glacial drift are least affected (14%). Drained thermokarst-lake basins are the most widespread thermokarst landforms, covering 33% of the entire study region, with greater prevalence in areas of marine silt (48% coverage), marine sand (47%), and aeolian silt (34%). Thermokarst-lakes are the second most common thermokarst landform, covering 16% of the study region, with highest coverage in areas underlain by marine silt (39% coverage). Thermokarst troughs and pits cover 7% of the study region and are the third most prevalent thermokarst landform. They are most common in areas underlain by deltaic sands and gravels (18% coverage) and marine sand (12%). Alas valleys are widespread in areas of aeolian silt (14%) located in gradually sloping uplands. Areas of marine silt have been particularly vulnerable to thaw in the past because they are ice-rich and have low-gradient topography facilitating the repeated development of thermokarst-lakes. In the future, ice-rich aeolian, upland terrain (yedoma) will be

  19. Spatial distribution of thermokarst terrain in Arctic Alaska

    Science.gov (United States)

    Farquharson, Louise; Mann, Dan H; Grosse, Guido; Jones, Benjamin M.; Romanovsky, Vladimir

    2016-01-01

    In landscapes underlain by ice-rich permafrost, the development of thermokarst landforms can have drastic impacts on ecosystem processes and human infrastructure. Here we describe the distribution of thermokarst landforms in the continuous permafrost zone of Arctic Alaska, analyze linkages to the underlying surficial geology, and discuss the vulnerability of different types of landscapes to future thaw. We identified nine major thermokarst landforms and then mapped their distributions in twelve representative study areas totaling 300-km2. These study areas differ in their geologic history, permafrost-ice content, and ground thermal regime. Results show that 63% of the entire study area is occupied by thermokarst landforms and that the distribution of thermokarst landforms and overall landscape complexity varies markedly with surficial geology. Areas underlain by ice-rich marine silt are the most affected by thermokarst (97% of total area), whereas areas underlain by glacial drift are least affected (14%). Drained thermokarst-lake basins are the most widespread thermokarst landforms, covering 33% of the entire study region, with greater prevalence in areas of marine silt (48% coverage), marine sand (47%), and aeolian silt (34%). Thermokarst-lakes are the second most common thermokarst landform, covering 16% of the study region, with highest coverage in areas underlain by marine silt (39% coverage). Thermokarst troughs and pits cover 7% of the study region and are the third most prevalent thermokarst landform. They are most common in areas underlain by deltaic sands and gravels (18% coverage) and marine sand (12%). Alas valleys are widespread in areas of aeolian silt (14%) located in gradually sloping uplands. Areas of marine silt have been particularly vulnerable to thaw in the past because they are ice-rich and have low-gradient topography facilitating the repeated development of thermokarst-lakes. In the future, ice-rich aeolian, upland terrain (yedoma) will be

  20. The limit distribution of the maximum increment of a random walk with regularly varying jump size distribution

    DEFF Research Database (Denmark)

    Mikosch, Thomas Valentin; Rackauskas, Alfredas

    2010-01-01

    In this paper, we deal with the asymptotic distribution of the maximum increment of a random walk with a regularly varying jump size distribution. This problem is motivated by a long-standing problem on change point detection for epidemic alternatives. It turns out that the limit distribution...... of the maximum increment of the random walk is one of the classical extreme value distributions, the Fréchet distribution. We prove the results in the general framework of point processes and for jump sizes taking values in a separable Banach space...

  1. 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.

  2. Richly parameterized linear models additive, time series, and spatial models using random effects

    CERN Document Server

    Hodges, James S

    2013-01-01

    A First Step toward a Unified Theory of Richly Parameterized Linear ModelsUsing mixed linear models to analyze data often leads to results that are mysterious, inconvenient, or wrong. Further compounding the problem, statisticians lack a cohesive resource to acquire a systematic, theory-based understanding of models with random effects.Richly Parameterized Linear Models: Additive, Time Series, and Spatial Models Using Random Effects takes a first step in developing a full theory of richly parameterized models, which would allow statisticians to better understand their analysis results. The aut

  3. 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 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.

  4. Spatial distribution of China׳s renewable energy industry

    DEFF Research Database (Denmark)

    Dong, Liang; Liang, Hanwei; Gao, Zhiqiu

    2016-01-01

    an empirical study on the distribution and cluster pattern of China׳s REEI based on the analysis on the industrial output value, the number and location of key companies/industrial bases, through on-site survey and updating statistical data. Results highlighted that in general, four REEI clusters were formed......China applies no efforts to promote the development of renewable energy (REE) so as to enhance China׳s energy security and address climate change. National top-down support scheme and the local renewable energy industry (REEI) development are the two important and intervened countermeasures...... in western China, while R&D and high-tech equipment manufacture were clustered in eastern coastal regions. Based on the empirical study and Analytic Network Process (ANP) of the roles of stakeholders involved REEI of China, we further proposed various strategic measures and policy implications to better...

  5. The spectrum of surface plasma polaritons under Gaussian spatial distribution of electrons

    CERN Document Server

    Dmitruk, M L; Mamontova, Y V

    2002-01-01

    Dispersion of surface electromagnetic waves (surface plasma polaritons, SPP) a nonhomogeneous solid-state plasma with Gaussian spatial distribution of electrons is calculated within the local dielectric function approximation. The calculated spatial distribution of electromagnetic fields allows one to identify the nature of the corresponding branches of the SPP dispersion. The attenuated total reflections spectrum is calculated for the Otto geometry of the experiment. The genesis of SPP dispersion curves under variation in the characteristic parameters of the solid-state plasma distribution is investigated as well.

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

    Li, Yun; Song, Yougui; Yan, Libin; Chen, Tao; An, Zhisheng

    2015-01-01

    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. 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.

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

    Directory of Open Access Journals (Sweden)

    T. Skaugen

    2016-09-01

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

  10. 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

  11. Geometry and spatial distribution of lenticulae on Europa

    Science.gov (United States)

    Culha, Cansu; Manga, Michael

    2016-06-01

    The surface of Europa contains several types of roughly elliptical features, collectively called lenticulae. Lenticulae may have positive relief (domes) or negative relief (pits), may disrupt the crust (chaos), or discolor the surface (spots); some lenticulae have attributes of both domes and chaos (dome/chaos). We map the location, dimensions and shapes of all lenticulae and their interactions with other lenticulae and lineaments. We find that (1) pits and domes have similar sizes; (2) chaos are larger than the other lenticulae; (3) pits are clustered within the trailing antijovian quadrant and the leading subjovian quadrant whereas domes, dome/chaos, and chaos terrains are more uniformly distributed; (4) the areal density for all lenticulae is not uniform; (5) lenticulae do not divert the path of younger lineaments such as ridges. Taken together, these observations are consistent with conceptual models in which lenticulae are created by intrusion of liquid water bodies, or convection within, the ice shell. Additionally, the observations are consistent with the notion that each type of lenticula is a surface expression of dynamics within the ice shell at a different stage of lenticulae evolution. The similar size and shape of pits and domes suggests that one may evolve into the other. Because domes are more numerous and more uniformly distributed than pits, they are more likely to represent the end stage of this evolution, assuming the end-stage leaves a longer-lasting surface expression. Models also predict that larger features are more likely to disrupt the crust, which is consistent with dome/chaos and chaos being larger than pits and domes. We find no examples of lineaments offsetting pits but lineaments do cross some chaos. Pits also have a preferred northwest-southeast elongation, whereas domes, dome/chaos, and chaos do not have a preferred orientation. If lenticulae orientation is influenced by crustal stress, then pits may have formed during a shorter time

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

    Directory of Open Access Journals (Sweden)

    Cloughley Richard

    2009-11-01

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

  13. 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.

  14. 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.

  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. Spatial tissue distribution of polyacetylenes in carrot root.

    Science.gov (United States)

    Baranska, Malgorzata; Schulz, Hartwig

    2005-06-01

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

  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. 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/

  19. 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.

  20. CONVERGENCE OF THE FRACTIONAL PARTS OF THE RANDOM VARIABLES TO THE TRUNCATED EXPONENTIAL DISTRIBUTION

    National Research Council Canada - National Science Library

    Bogdan Gheorghe Munteanu

    2013-01-01

    Using the stochastic approximations, in this paper it was studiedthe convergence in distribution of the fractional parts of the sum of random variables to the truncated exponential distribution with parameter lambda...

  1. Spatial distribution of Anaplasma phagocytophilum and Hepatozoon canis in red foxes (Vulpes vulpes) in Hungary.

    Science.gov (United States)

    Tolnai, Z; Sréter-Lancz, Z; Sréter, T

    2015-07-01

    In recent years, Ehrlichia canis and Hepatozoon canis transmitted by Rhipicephalus sanguineus were reported from Hungary. The aim of the present study was to reveal the spatial distribution pattern of pathogens transmitted by R. sanguineus in a sentinel species, red fox (Vulpes vulpes) in Hungary and to analyse the relationship of these patterns with landscape and climate by geographical information systems. Fox carcasses, representing 0.5% of the total fox population were randomly selected out of all the foxes of Hungary. The spleen samples of the animals were tested by real-time PCR for Anaplasma platys, Babesia vogeli, E. canis and H. canis infection. Positive results were confirmed by conventional PCR followed by sequencing. The prevalence of H. canis infection was 22.2% (95% CI=18.4-26.4%), and this parasite was detected in all areas including the mountain regions of Hungary. These findings indicate that other tick species or other transmission routes (oral and transplacental) might be in the background of the countrywide distribution of H. canis. Anaplasma platys was not found; nevertheless, the prevalence of Anaplasma phagocytophilum infection transmitted by Ixodes ricinus was 12.5% (95% CI=9.7-16.1%) in foxes. B. vogeli and E. canis infection was not detected. There was no correlation between environmental parameter values in the home range of foxes and A. phagocytophilum or H. canis infection, which is in line with that observed in the case of tick species infesting foxes in Hungary. The results of this study indicate that R. sanguineus, if present, might be rare in Hungary. Our baseline study can be used for future evaluation of the effect of climate change on the spreading and emergence of R. sanguineus transmitted pathogens in Hungary. Copyright © 2015 Elsevier GmbH. All rights reserved.

  2. Spatial organization and spatial distribution of activities within home ranges in a Springbok (Antidorcas marsupialis) captive population.

    Science.gov (United States)

    Mechkour, Farah; Maublanc, Marie-Line; Bideau, Eric; Gerard, Jean-François; Pépin, Dominique

    2008-01-01

    We studied over 1 year the spatial organization and the spatial distribution of activities in a captive springbok (Antidorcas marsupialis) population living in an 18-ha enclosure located in southern France. Throughout the study period, the two adult males occupied fairly exclusive home ranges, in the overlapping part of which the three subadult males were restricted. The spatial and temporal distribution of aggressive, marking, and avoidance behavior of males showed that the two adults were territorial, except during summer. They accounted for 71% of all marking behaviors recorded, for 77% of the aggressive behavior, and for 91% of the sexual interactions, whereas subadult males accounted for 94% of the avoidance behavior observed. The adult females used the whole enclosure, moving through the males' home ranges. They fed everywhere, but they all had the same preferred resting area, located in the center of the territory of one of the two adult males. They gave birth, accounted for maternal behavior and were engaged in sexual interactions in sectors differing from one individual to the other, but mainly outside the sector where all males' home ranges overlapped. Our results are compared to those reported in natural conditions and lead us to discuss both the functional interpretations of marking behavior, and the signification of a home range for an ungulate. Zoo Biol 27:19-35, 2008. (c) 2007 Wiley-Liss, Inc.

  3. Random Access Performance of Distributed Sensors Attacked by Unknown Jammers.

    Science.gov (United States)

    Jeong, Dae-Kyo; Wui, Jung-Hwa; Kim, Dongwoo

    2017-11-18

    In this paper, we model and investigate the random access (RA) performance of sensor nodes (SN) in a wireless sensor network (WSN). In the WSN, a central head sensor (HS) collects the information from distributed SNs, and jammers disturb the information transmission primarily by generating interference. In this paper, two jamming attacks are considered: power and code jamming. Power jammers (if they are friendly jammers) generate noises and, as a result, degrade the quality of the signal from SNs. Power jamming is equally harmful to all the SNs that are accessing HS and simply induces denial of service (DoS) without any need to hack HS or SNs. On the other hand, code jammers mimic legitimate SNs by sending fake signals and thus need to know certain system parameters that are used by the legitimate SNs. As a result of code jamming, HS falsely allocates radio resources to SNs. The code jamming hence increases the failure probability in sending the information messages, as well as misleads the usage of radio resources. In this paper, we present the probabilities of successful preamble transmission with power ramping according to the jammer types and provide the resulting throughput and delay of information transmission by SNs, respectively. The effect of two jamming attacks on the RA performances is compared with numerical investigation. The results show that, compared to RA without jammers, power and code jamming degrade the throughput by up to 30.3% and 40.5%, respectively, while the delay performance by up to 40.1% and 65.6%, respectively.

  4. Random Access Performance of Distributed Sensors Attacked by Unknown Jammers

    Directory of Open Access Journals (Sweden)

    Dae-Kyo Jeong

    2017-11-01

    Full Text Available In this paper, we model and investigate the random access (RA performance of sensor nodes (SN in a wireless sensor network (WSN. In the WSN, a central head sensor (HS collects the information from distributed SNs, and jammers disturb the information transmission primarily by generating interference. In this paper, two jamming attacks are considered: power and code jamming. Power jammers (if they are friendly jammers generate noises and, as a result, degrade the quality of the signal from SNs. Power jamming is equally harmful to all the SNs that are accessing HS and simply induces denial of service (DoS without any need to hack HS or SNs. On the other hand, code jammers mimic legitimate SNs by sending fake signals and thus need to know certain system parameters that are used by the legitimate SNs. As a result of code jamming, HS falsely allocates radio resources to SNs. The code jamming hence increases the failure probability in sending the information messages, as well as misleads the usage of radio resources. In this paper, we present the probabilities of successful preamble transmission with power ramping according to the jammer types and provide the resulting throughput and delay of information transmission by SNs, respectively. The effect of two jamming attacks on the RA performances is compared with numerical investigation. The results show that, compared to RA without jammers, power and code jamming degrade the throughput by up to 30.3% and 40.5%, respectively, while the delay performance by up to 40.1% and 65.6%, respectively.

  5. 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

  6. Relative importance of management, meteorological and environmental factors in the spatial distribution of Fasciola hepatica in dairy cattle in a temperate climate zone.

    Science.gov (United States)

    Bennema, S C; Ducheyne, E; Vercruysse, J; Claerebout, E; Hendrickx, G; Charlier, J

    2011-02-01

    Fasciola hepatica, a trematode parasite with a worldwide distribution, is the cause of important production losses in the dairy industry. Diagnosis is hampered by the fact that the infection is mostly subclinical. To increase awareness and develop regionally adapted control methods, knowledge on the spatial distribution of economically important infection levels is needed. Previous studies modelling the spatial distribution of F. hepatica are mostly based on single cross-sectional samplings and have focussed on climatic and environmental factors, often ignoring management factors. This study investigated the associations between management, climatic and environmental factors affecting the spatial distribution of infection with F. hepatica in dairy herds in a temperate climate zone (Flanders, Belgium) over three consecutive years. A bulk-tank milk antibody ELISA was used to measure F. hepatica infection levels in a random sample of 1762 dairy herds in the autumns of 2006, 2007 and 2008. The infection levels were included in a Geographic Information System together with meteorological, environmental and management parameters. Logistic regression models were used to determine associations between possible risk factors and infection levels. The prevalence and spatial distribution of F. hepatica was relatively stable, with small interannual differences in prevalence and location of clusters. The logistic regression model based on both management and climatic/environmental factors included the factors: annual rainfall, mowing of pastures, proportion of grazed grass in the diet and length of grazing season as significant predictors and described the spatial distribution of F. hepatica better than the model based on climatic/environmental factors only (annual rainfall, elevation and slope, soil type), with an Area Under the Curve of the Receiver Operating Characteristic of 0.68 compared with 0.62. The results indicate that in temperate climate zones without large climatic

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

    Directory of Open Access Journals (Sweden)

    Li Lin

    2015-04-01

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

  8. 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.

  9. Statistical analysis of the spatial distribution of operons in the transcriptional regulation network of Escherichia coli

    OpenAIRE

    Warren, P. B.; Wolde, P.R. ten

    2003-01-01

    We have performed a statistical analysis of the spatial distribution of operons in the transcriptional regulation network of Escherichia coli. The analysis reveals that operons that regulate each other and operons that are coregulated tend to lie next to each other on the genome. Moreover, these pairs of operons tend to be transcribed in diverging directions. This spatial arrangement of operons allows the upstream regulatory regions to interfere with each other. This affords additional regula...

  10. An exploratory spatial analysis of soil organic carbon distribution in Canadian eco-regions

    Science.gov (United States)

    Tan, S.-Y.; Li, J.

    2014-11-01

    As the largest carbon reservoir in ecosystems, soil accounts for more than twice as much carbon storage as that of vegetation biomass or the atmosphere. This paper examines spatial patterns of soil organic carbon (SOC) in Canadian forest areas at an eco-region scale of analysis. The goal is to explore the relationship of SOC levels with various climatological variables, including temperature and precipitation. The first Canadian forest soil database published in 1997 by the Canada Forest Service was analyzed along with other long-term eco-climatic data (1961 to 1991) including precipitation, air temperature, slope, aspect, elevation, and Normalized Difference Vegetation Index (NDVI) derived from remote sensing imagery. In addition, the existing eco-region framework established by Environment Canada was evaluated for mapping SOC distribution. Exploratory spatial data analysis techniques, including spatial autocorrelation analysis, were employed to examine how forest SOC is spatially distributed in Canada. Correlation analysis and spatial regression modelling were applied to determine the dominant ecological factors influencing SOC patterns at the eco-region level. At the national scale, a spatial error regression model was developed to account for spatial dependency and to estimate SOC patterns based on ecological and ecosystem factors. Based on the significant variables derived from the spatial error model, a predictive SOC map in Canadian forest areas was generated. Although overall SOC distribution is influenced by climatic and topographic variables, distribution patterns are shown to differ significantly between eco-regions. These findings help to validate the eco-region classification framework for SOC zonation mapping in Canada.

  11. Spatially intensive sampling by electrofishing for assessing longitudinal discontinuities in fish distribution in a headwater stream

    Science.gov (United States)

    Le Pichon, Céline; Tales, Évelyne; Belliard, Jérôme; Torgersen, Christian E.

    2017-01-01

    Spatially intensive sampling by electrofishing is proposed as a method for quantifying spatial variation in fish assemblages at multiple scales along extensive stream sections in headwater catchments. We used this method to sample fish species at 10-m2 points spaced every 20 m throughout 5 km of a headwater stream in France. The spatially intensive sampling design provided information at a spatial resolution and extent that enabled exploration of spatial heterogeneity in fish assemblage structure and aquatic habitat at multiple scales with empirical variograms and wavelet analysis. These analyses were effective for detecting scales of periodicity, trends, and discontinuities in the distribution of species in relation to tributary junctions and obstacles to fish movement. This approach to sampling riverine fishes may be useful in fisheries research and management for evaluating stream fish responses to natural and altered habitats and for identifying sites for potential restoration.

  12. Multilevel discretized random field models with 'spin' correlations for the simulation of environmental spatial data

    Science.gov (United States)

    Žukovič, Milan; Hristopulos, Dionissios T.

    2009-02-01

    A current problem of practical significance is how to analyze large, spatially distributed, environmental data sets. The problem is more challenging for variables that follow non-Gaussian distributions. We show by means of numerical simulations that the spatial correlations between variables can be captured by interactions between 'spins'. The spins represent multilevel discretizations of environmental variables with respect to a number of pre-defined thresholds. The spatial dependence between the 'spins' is imposed by means of short-range interactions. We present two approaches, inspired by the Ising and Potts models, that generate conditional simulations of spatially distributed variables from samples with missing data. Currently, the sampling and simulation points are assumed to be at the nodes of a regular grid. The conditional simulations of the 'spin system' are forced to respect locally the sample values and the system statistics globally. The second constraint is enforced by minimizing a cost function representing the deviation between normalized correlation energies of the simulated and the sample distributions. In the approach based on the Nc-state Potts model, each point is assigned to one of Nc classes. The interactions involve all the points simultaneously. In the Ising model approach, a sequential simulation scheme is used: the discretization at each simulation level is binomial (i.e., ± 1). Information propagates from lower to higher levels as the simulation proceeds. We compare the two approaches in terms of their ability to reproduce the target statistics (e.g., the histogram and the variogram of the sample distribution), to predict data at unsampled locations, as well as in terms of their computational complexity. The comparison is based on a non-Gaussian data set (derived from a digital elevation model of the Walker Lake area, Nevada, USA). We discuss the impact of relevant simulation parameters, such as the domain size, the number of

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

    Science.gov (United States)

    Jinhai, C.; Feng, L.; Guojun, P.

    2014-02-01

    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.

  14. 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.

  15. 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.

  16. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Burnet

    2015-09-01

    Full Text Available Background: 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. Methods: 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. Results: Parasites displayed heterogeneous distribution patterns, as reflected by significant (oocyst 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. Conclusion: 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.

  17. Optimization of spatial light distribution through genetic algorithms for vision systems applied to quality control

    Science.gov (United States)

    Castellini, P.; Cecchini, S.; Stroppa, L.; Paone, N.

    2015-02-01

    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.

  18. 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.

  19. Experiments with central-limit properties of spatial samples from locally covariant random fields

    Science.gov (United States)

    Barringer, T.H.; Smith, T.E.

    1992-01-01

    When spatial samples are statistically dependent, the classical estimator of sample-mean standard deviation is well known to be inconsistent. For locally dependent samples, however, consistent estimators of sample-mean standard deviation can be constructed. The present paper investigates the sampling properties of one such estimator, designated as the tau estimator of sample-mean standard deviation. In particular, the asymptotic normality properties of standardized sample means based on tau estimators are studied in terms of computer experiments with simulated sample-mean distributions. The effects of both sample size and dependency levels among samples are examined for various value of tau (denoting the size of the spatial kernel for the estimator). The results suggest that even for small degrees of spatial dependency, the tau estimator exhibits significantly stronger normality properties than does the classical estimator of standardized sample means. ?? 1992.

  20. CONVERGENCE OF THE FRACTIONAL PARTS OF THE RANDOM VARIABLES TO THE TRUNCATED EXPONENTIAL DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Bogdan Gheorghe Munteanu

    2013-01-01

    Full Text Available Using the stochastic approximations, in this paper it was studiedthe convergence in distribution of the fractional parts of the sum of random variables to the truncated exponential distribution with parameter lambda. This fact is feasible by means of the Fourier-Stieltjes sequence (FSS of the random variable.

  1. Algorithm for generation pseudo-random series with arbitrarily assigned distribution law

    Directory of Open Access Journals (Sweden)

    В.С. Єременко

    2005-04-01

    Full Text Available  Method for generation pseudo-random series with arbitrarily assigned distribution law has been proposed. The praxis of using proposed method for generation pseudo-random series with anti-modal and approximate to Gaussian distribution law has been investigated.

  2. Evaluating the Use of Random Distribution Theory to Introduce Statistical Inference Concepts to Business Students

    Science.gov (United States)

    Larwin, Karen H.; Larwin, David A.

    2011-01-01

    Bootstrapping methods and random distribution methods are increasingly recommended as better approaches for teaching students about statistical inference in introductory-level statistics courses. The authors examined the effect of teaching undergraduate business statistics students using random distribution and bootstrapping simulations. It is the…

  3. Assessing the spatial distribution of glyphosate-AMPA in an Argentinian farm field using a pedometric technique

    Science.gov (United States)

    Barbera, Agustin; Zamora, Martin; Domenech, Marisa; Vega-Becerra, Andres; Castro-Franco, Mauricio

    2017-04-01

    The cultivation of transgenic glyphosate-resistant crops has been the most rapidly adopted crop technology in Argentina since 1997. Thus, more than 180 million liters of the broad-spectrum herbicide glyphosate (N - phosphonomethylglicine) are applied every year. The intensive use of glyphosate combined with geomorphometrical characteristics of the Pampa region is a matter of environmental concern. An integral component of assessing the risk of soil contamination in farm fields is to describe the spatial distribution of the levels of contaminant agent. Application of pedometric techniques for this purpose has been scarcely demonstrated. These techniques could provide an estimate of the concentration at a given unsampled location, as well as the probability that concentration will exceed the critical threshold concentration. In this work, a pedometric technique for assessing the spatial distribution of glyphosate in farm fields was developed. A field located at INTA Barrow, Argentina (Lat: -38.322844, Lon: -60.25572) which has a great soil spatial variability, was divided by soil-specific zones using a pedometric technique. This was developed integrating INTA Soil Survey information and a digital elevation model (DEM) obtained from a DGPS. Firstly, 10 topographic indices derived from a DEM were computed in a Random Forest algorithm to obtain a classification model for soil map units (SMU). Secondly, a classification model was applied to those topographic indices but at a scale higher than 1:1000. Finally, a spatial principal component analysis and a clustering using Fuzzy K-means were used into each SMU. From this clustering, three soil-specific zones were determined which were also validated through apparent electrical conductivity (CEa) measurements. Three soil sample points were determined by zone. In each one, samples from 0-10, 10-20 and 20-40cm depth were taken. Glyphosate content and AMPA in each soil sample were analyzed using de UPLC-MS/MS ESI (+/-). Only

  4. Spatial distribution of fiber types in skeletal muscle: test for a random distribution

    NARCIS (Netherlands)

    Venema, H. W.

    1988-01-01

    A statistical test is introduced for the assessment of fiber type grouping based on the number of neighboring fibers of different histochemical type. It is conceptually simple and can be applied to regular and irregular fiber patterns alike. One important feature of this test is that it has more

  5. Retrieval of spatially distributed hydrological properties from satellite observations for spatial evaluation of a national water resources model.

    Science.gov (United States)

    Mendiguren González, G.; Stisen, S.; Koch, J.

    2016-12-01

    The validation of traditional hydrological models is often carried out by aggregating all catchment observations at a single discharge point and therefore ignoring the spatial component of the model performance. Distributed hydrological models offer new possibilities, however development of new methodologies to calibrate and validate the spatial pattern of the model outputs is still necessary. The use of satellite earth observation (EO) platforms provides valuable information that can be used in the hydrological models in two different ways; as EO derived variables (Leaf Area Index (LAI), Albedo among others) to run the models, or/and secondly in the evaluation of the hydrological model outputs i.e evapotranspiration (ET). In this study we have used a time series of MODIS arcade data from 2002 to 2014 to generate a dataset that allowed us to run the MIKE-SHE based National Water Resources Model (NWRS) of Denmark with EO generated inputs and to calculate ET using the Two Source Energy Balance (TSEB) model proposed by Norman in 1995 and based on Priestley Taylor approximation to evaluate the ET outputs of the NWRS model. We conducted a sensitivity analysis of the TSEB using a Parameter Estimation Tool (PEST) and evaluated the ET estimates using Eddy Covariance (EC) from three different flux towers located in different sites covering an agriculture field, a forest area and a wetland. The spatial patterns of the MIKE-SHE outputs for ET were compared with the ET obtained from MODIS on a monthly mean basis. Two spatial comparisons using Fraction Skill Score (FSS) and Empirical Orthogonal Functions (EOF) evaluated the spatial patterns in two different cases. First the original configuration of the NWRS model where the root depth is parametrized based on look up tables and second, where we substituted the root depth in the NWRS model by the one based on vegetation data from MODIS. Results highlighted the potential of using EO data to improve the spatial performance of

  6. Dispersal leads to spatial autocorrelation in species distributions: A simulation model

    Science.gov (United States)

    Bahn, V.; Krohn, W.B.; O'Connor, R.J.

    2008-01-01

    Compared to population growth regulated by local conditions, dispersal has been underappreciated as a central process shaping the spatial distribution of populations. This paper asks: (a) which conditions increase the importance of dispersers relative to local recruits in determining population sizes? and (b) how does dispersal influence the spatial distribution patterns of abundances among connected populations? We approached these questions with a simulation model of populations on a coupled lattice with cells of continuously varying habitat quality expressed as carrying capacities. Each cell contained a population with the basic dynamics of density-regulated growth, and was connected to other populations by immigration and emigration. The degree to which dispersal influenced the distribution of population sizes depended most strongly on the absolute amount of dispersal, and then on the potential population growth rate. Dispersal decaying in intensity with distance left close neighbours more alike in population size than distant populations, leading to an increase in spatial autocorrelation. The spatial distribution of species with low potential growth rates is more dependent on dispersal than that of species with high growth rates; therefore, distribution modelling for species with low growth rates requires particular attention to autocorrelation, and conservation management of these species requires attention to factors curtailing dispersal, such as fragmentation and dispersal barriers. ?? 2007 Elsevier B.V. All rights reserved.

  7. Relationships between dendritic morphology, spatial distribution and firing patterns in rat layer 1 neurons

    Directory of Open Access Journals (Sweden)

    D.V.V. Santos

    2012-12-01

    Full Text Available The cortical layer 1 contains mainly small interneurons, which have traditionally been classified according to their axonal morphology. The dendritic morphology of these cells, however, has received little attention and remains ill defined. Very little is known about how the dendritic morphology and spatial distribution of these cells may relate to functional neuronal properties. We used biocytin labeling and whole cell patch clamp recordings, associated with digital reconstruction and quantitative morphological analysis, to assess correlations between dendritic morphology, spatial distribution and membrane properties of rat layer 1 neurons. A total of 106 cells were recorded, labeled and subjected to morphological analysis. Based on the quantitative patterns of their dendritic arbor, cells were divided into four major morphotypes: horizontal, radial, ascendant, and descendant cells. Descendant cells exhibited a highly distinct spatial distribution in relation to other morphotypes, suggesting that they may have a distinct function in these cortical circuits. A significant difference was also found in the distribution of firing patterns between each morphotype and between the neuronal populations of each sublayer. Passive membrane properties were, however, statistically homogeneous among all subgroups. We speculate that the differences observed in active membrane properties might be related to differences in the synaptic input of specific types of afferent fibers and to differences in the computational roles of each morphotype in layer 1 circuits. Our findings provide new insights into dendritic morphology and neuronal spatial distribution in layer 1 circuits, indicating that variations in these properties may be correlated with distinct physiological functions.

  8. Analysis of Spatial Distribution And Statistical Characteristics of Typhoon In The Western Pacific Based On Spatial Point Model

    Science.gov (United States)

    Wang, Jingmei; Gong, Adu; Li, Jing; Chen, Yanling

    2017-04-01

    Typhoon is a kind of strong weather system formed in tropical or subtropical oceans. China, located on the west side of the Pacific Ocean, is the country affected by the typhoon most frequently and seriously. To provide theoretical support for effectively reducing the damage caused by typhoon, the variation law of typhoon frequency is explored by analyzing the distribution of typhoon path and landing sites, sphere of influence, and the statistical characteristics of typhoon for every 5 years. In this study, the typhoon point data set was formed using the Best Path Data Set (0.1 ° × 0.1 °) compiled by China Meteorological Administration from 1950 to 2014. By using the tool of Point to Line in software ArgGIS, the typhoon paths are produced from the point data set. The influence sphere of typhoon is calculated from Euclidean distance of typhoon, whose threshold is set to 1°.The typhoon landing site was extracted by using the Chinese vector layer provided by the research group. By counting the frequency of typhoons, the landing sites, and the sphere of influence, some conclusions can be drawn as follows. In recent years, the number of typhoons generated has been reduced, typhoon intensity is relatively stable, but the impact of typhoon area has increased. Specific performance can be seen from the typhoon statistical and spatial distribution characteristics in China. In terms of frequency of typhoon landing, the number of typhoons landing in China has increased while the total number of typhoons is reduced. In terms of distribution of landing sites, the range of typhoon landing fluctuates. However, during the process of fluctuation, the range is gradually expanding. For example, in south of China, Hainan Island is affected by typhoon more frequently meanwhile China's northeast region is also gradually affected, which is extremely unusual before. Key words: spatial point model, distribution of typhoon, frequency of typhoon

  9. Distribution of local density of states in superstatistical random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Abul-Magd, A.Y. [Department of Mathematics, Faculty of Science, Zagazig University, Zagazig (Egypt)]. E-mail: a_y_abul_magd@hotmail.com

    2007-07-02

    We expose an interesting connection between the distribution of local spectral density of states arising in the theory of disordered systems and the notion of superstatistics introduced by Beck and Cohen and recently incorporated in random matrix theory. The latter represents the matrix-element joint probability density function as an average of the corresponding quantity in the standard random-matrix theory over a distribution of level densities. We show that this distribution is in reasonable agreement with the numerical calculation for a disordered wire, which suggests to use the results of theory of disordered conductors in estimating the parameter distribution of the superstatistical random-matrix ensemble.

  10. Temperature Grid Sensor for the Measurement of Spatial Temperature Distributions at Object Surfaces

    OpenAIRE

    Uwe Hampel; Thomas Schäfer; Markus Schubert

    2013-01-01

    This paper presents results of the development and application of a new temperature grid sensor based on the wire-mesh sensor principle. The grid sensor consists of a matrix of 256 Pt1000 platinum chip resistors and an associated electronics that measures the grid resistances with a multiplexing scheme at high speed. The individual sensor elements can be spatially distributed on an object surface and measure transient temperature distributions in real time. The advantage compared with other t...

  11. Spatial distribution modelling of the endangered bivalve Pinna nobilis in a Marine Protected Area

    OpenAIRE

    Vázquez-Luis, M. (Maite); De March, D.; Alvarez, E.; ALVAREZ-BERASTEGUI, D.; DEUDERO, S.

    2016-01-01

    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 ...

  12. MOCCA code for star cluster simulations - VI. Bimodal spatial distribution of blue stragglers

    OpenAIRE

    Hypki, Arkadiusz; Giersz, Mirek

    2016-01-01

    The paper presents an analysis of formation mechanism and properties of spatial distributions of blue stragglers in evolving globular clusters, based on numerical simulations done with the MOCCA code. First, there are presented N-body and MOCCA simulations which try to reproduce the simulations presented by Ferraro (2012). Then, the agreement between N-body and the MOCCA code is shown. Finally, we discuss the formation process of the bimodal distribution. We report that so-called bimodal spat...

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

    OpenAIRE

    Tulio Chiarini; Vanessa Parreiras de 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 ...

  14. Global assessment of soil organic carbon stocks and spatial distribution of histosols: the Machine Learning approach

    Science.gov (United States)

    Hengl, Tomislav

    2016-04-01

    Preliminary results of predicting distribution of soil organic soils (Histosols) and soil organic carbon stock (in tonnes per ha) using global compilations of soil profiles (about 150,000 points) and covariates at 250 m spatial resolution (about 150 covariates; mainly MODIS seasonal land products, SRTM DEM derivatives, climatic images, lithological and land cover and landform maps) are presented. We focus on using a data-driven approach i.e. Machine Learning techniques that often require no knowledge about the distribution of the target variable or knowledge about the possible relationships. Other advantages of using machine learning are (DOI: 10.1371/journal.pone.0125814): All rules required to produce outputs are formalized. The whole procedure is documented (the statistical model and associated computer script), enabling reproducible research. Predicted surfaces can make use of various information sources and can be optimized relative to all available quantitative point and covariate data. There is more flexibility in terms of the spatial extent, resolution and support of requested maps. Automated mapping is also more cost-effective: once the system is operational, maintenance and production of updates are an order of magnitude faster and cheaper. Consequently, prediction maps can be updated and improved at shorter and shorter time intervals. Some disadvantages of automated soil mapping based on Machine Learning are: Models are data-driven and any serious blunders or artifacts in the input data can propagate to order-of-magnitude larger errors than in the case of expert-based systems. Fitting machine learning models is at the order of magnitude computationally more demanding. Computing effort can be even tens of thousands higher than if e.g. linear geostatistics is used. Many machine learning models are fairly complex often abstract and any interpretation of such models is not trivial and require special multidimensional / multivariable plotting and data mining

  15. Distributed hydrological models for addressing effects of spatial variability of roughness on overland flow

    Directory of Open Access Journals (Sweden)

    Sheng-tang Zhang

    2016-07-01

    Full Text Available In this study, we investigated the origin of the overland flow roughness problem and divided the current overland flow roughness research into three types, as follows: the first type of research takes into account the effects of roughness on the volume and velocity of surface runoff, flood peaks, and the scouring capability of flows, but has not addressed the spatial variability of roughness in detail; the second type of research considers that surface roughness varies spatially with different land usage types, land-cover conditions, and different tillage forms, but lacks a quantitative study of the spatial variability; and the third type of research simply deals with the spatial variability of roughness in each grid cell or land type. We present three shortcomings of the current overland flow roughness research, including (1 the neglect of roughness in distributed hydrological models when simulating the overland flow direction and distribution, (2 the lack of consideration of spatial variability of roughness in hydrological models, and (3 the failure to distinguish the roughness formulas in different overland flow regimes. To solve these problems, distributed hydrological model research should focus on four aspects in regard to overland flow: velocity field observations, flow regime mechanisms, a basic roughness theory, and scale problems.

  16. [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.

  17. mocca code for star cluster simulations - VI. Bimodal spatial distribution of blue stragglers

    Science.gov (United States)

    Hypki, Arkadiusz; Giersz, Mirek

    2017-11-01

    The paper presents an analysis of formation mechanism and properties of spatial distributions of blue stragglers in evolving globular clusters, based on numerical simulations done with the mocca code. First, there are presented N-body and mocca simulations which try to reproduce the simulations presented by Ferraro et al. (2012). Then, we show the agreement between N-body and the mocca code. Finally, we discuss the formation process of the bimodal distribution. We report that we could not reproduce simulations from Ferraro et al. (2012). Moreover, we show that the so-called bimodal spatial distribution of blue stragglers is a very transient feature. It is formed for one snapshot in time and it can easily vanish in the next one. Moreover, we show that the radius of avoidance proposed by Ferraro et al. (2012) goes out of sync with the apparent minimum of the bimodal distribution after about two half-mass relaxation times (without finding out what is the reason for that). This finding creates a real challenge for the dynamical clock, which uses this radius to determine the dynamical age of globular clusters. Additionally, the paper discusses a few important problems concerning the apparent visibilities of the bimodal distributions, which have to be taken into account while studying the spatial distributions of blue stragglers.

  18. Bayesian Clustering Using Hidden Markov Random Fields in Spatial Population Genetics

    Science.gov (United States)

    François, Olivier; Ancelet, Sophie; Guillot, Gilles

    2006-01-01

    We introduce a new Bayesian clustering algorithm for studying population structure using individually geo-referenced multilocus data sets. The algorithm is based on the concept of hidden Markov random field, which models the spatial dependencies at the cluster membership level. We argue that (i) a Markov chain Monte Carlo procedure can implement the algorithm efficiently, (ii) it can detect significant geographical discontinuities in allele frequencies and regulate the number of clusters, (iii) it can check whether the clusters obtained without the use of spatial priors are robust to the hypothesis of discontinuous geographical variation in allele frequencies, and (iv) it can reduce the number of loci required to obtain accurate assignments. We illustrate and discuss the implementation issues with the Scandinavian brown bear and the human CEPH diversity panel data set. PMID:16888334

  19. Mammographic Breast Density in Chinese Women: Spatial Distribution and Autocorrelation Patterns.

    Science.gov (United States)

    Lai, Christopher W K; Law, Helen K W

    2015-01-01

    Mammographic breast density (MBD) is a strong risk factor for breast cancer. The spatial distribution of MBD in the breast is variable and dependent on physiological, genetic, environmental and pathological factors. This pilot study aims to define the spatial distribution and autocorrelation patterns of MBD in Chinese women aged 40-60. By analyzing their digital mammographic images using a public domain Java image processing program for segmentation and quantification of MBD, we found their left and right breasts were symmetric to each other in regard to their breast size (Total Breast Area), the amount of BMD (overall PD) and Moran's I values. Their MBD was also spatially autocorrelated together in the anterior part of the breast in those with a smaller breast size, while those with a larger breast size tend to have their MBD clustered near the posterior part of the breast. Finally, we observed that the autocorrelation pattern of MBD was dispersed after a 3-year observation period.

  20. Characterization of the spatial distribution of farming systems in the Kenyan Highlands

    NARCIS (Netherlands)

    Steeg, J.A.; Verburg, P.H.; Baltenweck, I.; Staal, S.J.

    2010-01-01

    Land cover change maps are not sufficient to identify subtle changes in land use and farming systems. This paper describes a method that is developed to identify the spatial distribution of farming system types without the need to extensively map all farming systems across a large region. Moreover,

  1. Method for Quantitative Determination of Spatial Polymer Distribution in Alginate Beads Using Raman Spectroscopy

    NARCIS (Netherlands)

    Heinemann, Matthias; Meinberg, Holger; Büchs, Jochen; Koß, Hans-Jürgen; Ansorge-Schumacher, Marion B.

    2005-01-01

    A new method based on Raman spectroscopy is presented for non-invasive, quantitative determination of the spatial polymer distribution in alginate beads of approximately 4 mm diameter. With the experimental setup, a two-dimensional image is created along a thin measuring line through the bead

  2. 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.

  3. Edge effect causes apparent fractal correlation dimension of uniform spatial raindrop distribution

    NARCIS (Netherlands)

    Uijlenhoet, R.; Porra, J.M.; Sempere Torres, D.; Creutin, J.D.

    2009-01-01

    Lovejoy and Schertzer (1990a) presented a statistical analysis of blotting paper observations of the (two-dimensional) spatial distribution of raindrop stains. They found empirical evidence for the fractal scaling behavior of raindrops in space, with potentially far-reaching implications for

  4. 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 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.

  5. Vibration suppression for strings with distributed loading using spatial cross-section modulation

    DEFF Research Database (Denmark)

    Sorokin, Vladislav; Thomsen, Jon Juel

    2015-01-01

    A problem of vibration suppression in any preassigned region of a bounded structure subjected to action of an external time-periodic load which is distributed over its domain is considered. A passive control is applied, in which continuous spatially periodic modulations of structural parameters a...

  6. Predicting Spatial Distribution of Infection Risk of Airborne Transmission Diseases in a Hospital Ward

    DEFF Research Database (Denmark)

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

    2007-01-01

    This study attempt to integrate the Wells-Riley equation and computational fluid dynamics for analyzing the risk of airborne transmission diseases in a building. The new method can predict the spatial distribution of the infection risk of the airborne transmission diseases in a large hospital war...

  7. CONSIDERATIONS CONCERNING THE SPATIAL DISTRIBUTION OF SOILS IN THE CENTRAL MOLDAVIAN TABLELAND

    OpenAIRE

    V. Budui

    2006-01-01

    The spatial distribution of soils in central Moldavian Tableland is influenced by climate, vegetation and geomorphological characteristics (slope, altitude). Representative soils of this region are cernisol (cernoziom and faeoziom) and luvisol (preluvosol and luvosol). Another pedological characteristic of this region is soil erosion that affects sloped versants.

  8. 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 det...

  9. Spatial distribution of bacteria associated with the marine sponge Tethya californiana

    NARCIS (Netherlands)

    Sipkema, D.; Blanch, H.W.

    2010-01-01

    Microbial diversity and spatial distribution of the diversity within tissue of the marine sponge Tethya californiana was analyzed based on 16S rRNA gene sequences. One candidate division and nine bacterial phyla were detected, including members of all five subdivisions of Proteobacteria. Moreover,

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

    NARCIS (Netherlands)

    Cianci, Daniela; Hartemink, Nienke; Ibáñez-Justicia, Adolfo

    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

  11. Modeling and Spatially Distributing Forest Net Primary Production at the Regional Scale

    Science.gov (United States)

    R.A. Mickler; T.S. Earnhardt; J.A. Moore

    2002-01-01

    Abstract - Forest, agricultural, rangeland, wetland, and urban landscapes have different rates of carbon sequestration and total carbon sequestration potential under alternative management options. Changes in the proportion and spatial distribution of land use could enhance or degrade that area’s ability to sequester carbon in terrestrial ecosystems...

  12. 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.

  13. A spatially distributed model of pesticide movement in Dutch macroporous soils

    NARCIS (Netherlands)

    Tiktak, A.; Hendriks, R.F.A.; Boesten, J.J.T.I.; Linden, van der A.M.A.

    2012-01-01

    In the Netherlands, a spatially distributed version of the pesticide fate model PEARL is routinely used to assess the leaching potential of pesticides to groundwater. Recently, the model was modified to simulate the movement of pesticides to surface water. The peak concentration is considered to be

  14. Spatial distribution of non-clinical Rift Valley fever viral activity in ...

    African Journals Online (AJOL)

    Rift Valley fever (RVF) is an acute zoonotic viral disease of domestic ruminants in mainland Africa and Madagascar. The disease may exist in non-clinical form in apparently health animals. This study was designed to investigate the existence and spatial distribution of non-clinical form of RVF virus (RVFV) activity in wild and ...

  15. CONSIDERATIONS CONCERNING THE SPATIAL DISTRIBUTION OF SOILS IN THE CENTRAL MOLDAVIAN TABLELAND

    Directory of Open Access Journals (Sweden)

    V. Budui

    2006-10-01

    Full Text Available The spatial distribution of soils in central Moldavian Tableland is influenced by climate, vegetation and geomorphological characteristics (slope, altitude. Representative soils of this region are cernisol (cernoziom and faeoziom and luvisol (preluvosol and luvosol. Another pedological characteristic of this region is soil erosion that affects sloped versants.

  16. Glaciers as a proxy to quantify the spatial distribution of precipitation in the Hunza basin

    NARCIS (Netherlands)

    Immerzeel, W.W.; Pellicciotti, F.; Shrestha, A.B.

    2012-01-01

    Accurate quantification of the spatial distribution of precipitation in mountain regions is crucial for assessments of water resources and for the understanding of highaltitude hydrology, yet it is one of the largest unknowns due to the lack of high-altitude observations. The Hunza basin

  17. 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

  18. Interference competition, the spatial distribution of food and free-living foragers

    NARCIS (Netherlands)

    Vahl, Wouter K.; Van der Meer, Jaap; Meijer, Kim; Piersma, Theunis; Weissing, Franz J.

    2007-01-01

    Studies of interference competition among foraging animals generally assume that variation in the spatial distribution of food can be neglected. This assumption may be problematic as resource defence experiments suggest that such variation is of the essence in some interference mechanisms.

  19. Modelling the effect of intersections in linear habitat on spatial distribution and local population density

    NARCIS (Netherlands)

    Langevelde, van F.; Grashof-Bokdam, C.J.

    2011-01-01

    Many species in human-dominated landscapes find their habitat in linear elements, such as road verges, hedgerows and ditches. Local concentrations of species have been observed in the intersections of linear elements, but their spatial distribution and local population density in this linear habitat

  20. Dairy cow defecation and urination frequency and spatial distribution in relation to time-limited grazing

    NARCIS (Netherlands)

    Oudshoorn, F.W.; Kristensen, T.; Sharak Nadimi, I.

    2008-01-01

    The objective of this paper was to investigate the effect of limited grazing time on urination and defecation frequency, spatial distribution of excrement in the paddock, and the resulting nitrogen balance at animal and field level. During a 6-week period in early summer, 60 Holstein Frisian dairy

  1. Modeling species distribution and change using random forest [Chapter 8

    Science.gov (United States)

    Jeffrey S. Evans; Melanie A. Murphy; Zachary A. Holden; Samuel A. Cushman

    2011-01-01

    Although inference is a critical component in ecological modeling, the balance between accurate predictions and inference is the ultimate goal in ecological studies (Peters 1991; De’ath 2007). Practical applications of ecology in conservation planning, ecosystem assessment, and bio-diversity are highly dependent on very accurate spatial predictions of...

  2. Spatial Distribution of Adults of Triozoida limbata (Enderlein) (Hemiptera: Triozidae) in Guava Plants.

    Science.gov (United States)

    Marcelino, M C S; Barbosa, J C

    2016-04-01

    The psyllid Triozoida limbata (Enderlein) (Hemiptera: Triozidae) is a major pest in guava, feeding primarily on new shoots. Despite its importance, there are no studies on the spatial distribution of T. limbata on guava. Such studies are needed to establish sequential sampling plans for decision making in pest control. Thus, an experiment was carried out in a 9-year-old commercial guava orchard divided into 100 sampling units or plots. Double-sided yellow sticky traps were placed on one plant per plot (sample unit) to capture and monitor T. limbata adults from April 2011 to May 2012. To determine the insect distribution in the area, we calculated the variance-to-mean ratio index (I), the Morisita index (I δ ), Green's coefficient (Cx), and the k exponent of the negative binomial distribution. Most of the samples showed that the adults had a moderate to highly aggregated distribution. Statistical models were also used to study the pest spatial distribution by fitting the number of adults captured to the Poisson and negative binomial distributions. The negative binomial distribution model best fitted the data of the number of adult psyllids captured by the traps, which is consistent with an aggregated distribution.

  3. Bimodal spatial distribution of macular pigment: evidence of a gender relationship

    Science.gov (United States)

    Delori, François C.; Goger, Douglas G.; Keilhauer, Claudia; Salvetti, Paola; Staurenghi, Giovanni

    2006-03-01

    The spatial distribution of the optical density of the human macular pigment measured by two-wavelength autofluorescence imaging exhibits in over half of the subjects an annulus of higher density superimposed on a central exponential-like distribution. This annulus is located at about 0.7° from the fovea. Women have broader distributions than men, and they are more likely to exhibit this bimodal distribution. Maxwell's spot reported by subjects matches the measured distribution of their pigment. Evidence that the shape of the foveal depression may be gender related leads us to hypothesize that differences in macular pigment distribution are related to anatomical differences in the shape of the foveal depression.

  4. 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......, groundwater recharge, and groundwater head were also affected by the method for correction of systematic errors in precipitation measurements. The results underscored the importance of using a spatial resolution of the precipitation input that captures the overall precipitation characteristics...

  5. 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.

  6. 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.

  7. Spatial Distribution and Coexisting Patterns of Adults and Nymphs of Tibraca limbativentris (Hemiptera: Pentatomidae) in Paddy Rice Fields.

    Science.gov (United States)

    Alves, Tavvs M; Maia, Aline H N; Barrigossi, José A F

    2016-12-01

    The rice stem stink bug, Tibraca limbativentris Stål (Hemiptera: Pentatomidae), is a primary insect pest of paddy rice in South America. Knowledge of its spatial distribution can support sampling plans needed for timely decisions about pest control. This study aimed to investigate the spatial distribution of adults and nymphs of T. limbativentris and determine the spatial coexistence of these stages of development. Fifteen paddy rice fields were scouted once each season to estimate insect densities. Scouting was performed on regular grids with sampling points separated by ∼50 m. Moran's I and semivariograms were used to determine spatial distribution patterns. Spatial coexistence of nymphs and adults was explored via spatial point process. Here, adults and nymphs had typically contrasting spatial distribution patterns within the same field; however, the frequency of aggregation was not different between these developmental stages. Adults and nymphs were aggregated in seven fields and randomly distributed in the other eight fields. Uniform distribution of adults or nymphs was not observed. The study-wide semivariogram ranges were ∼40 m for adults and ∼55 m for nymphs. Nymphs and adults spatially coexisted on 67% of the fields. Coexisting patterns were classified using one of the following processes: stage-independent, bidirectional attractive, unidirectional attractive, bidirectional inhibiting, or unidirectional inhibiting. The information presented herein can be important for developing sampling plans for decision-making, implementing tactics for site-specific management, and monitoring areas free of T. limbativentrisResumoO percevejo-do-colmo Tibraca limbativentris Stål (Hemiptera: Pentatomidae) é uma praga primária na cultura do arroz irrigado na América do Sul. O conhecimento de sua distribuição espacial é essencial para desenvolver planos de amostragem e para o controle desta praga. Nosso objetivo foi investigar a distribuição espacial de

  8. Analysis of the spatial distribution of prostate cancer obtained from histopathological images

    Science.gov (United States)

    Diaz, Kristians; Castaneda, Benjamin; Montero, Maria Luisa; Yao, Jorge; Joseph, Jean; Rubens, Deborah; Parker, Kevin J.

    2013-03-01

    Understanding the spatial distribution of prostate cancer and how it changes according to prostate specific antigen (PSA) values, Gleason score, and other clinical parameters may help comprehend the disease and increase the overall success rate of biopsies. This work aims to build 3D spatial distributions of prostate cancer and examine the extent and location of cancer as a function of independent clinical parameters. The border of the gland and cancerous regions from wholemount histopathological images are used to reconstruct 3D models showing the localization of tumor. This process utilizes color segmentation and interpolation based on mathematical morphological distance. 58 glands are deformed into one prostate atlas using a combination of rigid, affine, and b-spline deformable registration techniques. Spatial distribution is developed by counting the number of occurrences in a given position in 3D space from each registered prostate cancer. Finally a difference between proportions is used to compare different spatial distributions. Results show that prostate cancer has a significant difference (SD) in the right zone of the prostate between populations with PSA greater and less than 5ng/ml. Age does not have any impact in the spatial distribution of the disease. Positive and negative capsule-penetrated cases show a SD in the right posterior zone. There is SD in almost all the glands between cases with tumors larger and smaller than 10% of the whole prostate. A larger database is needed to improve the statistical validity of the test. Finally, information from whole-mount histopathological images may provide better insight into prostate cancer.

  9. The spatial distribution of ultraviolet line and continuum emission in Herbig-Haro objects

    Science.gov (United States)

    Lee, M. G.; Boehm, K. H.; Temple, S. D.; Raga, A. C.; Mateo, M. L.

    1988-01-01

    Archival IUE data and monochromatic CCD images in the optical range are used to compare the spatial distribution of UV and optical emission in HH 1, HH 2, HH 24, HH 32, HH 43, and HH 47. For all six objects, the observed UV radiation is shown to originate in the objects themselves. The results indicate that the C IV and semiforbidden emission-line regions are small. Although the continuum in the IUE short-wavelength range displays a distribution that is broader than that of any measured line emission in the UV or optical range, the continuum distribution in the IUE long-wavelength range is quite narrow.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    This study presents an algorithm to optimally aggregate spatially distributed flexible resources at strategic microgrid/smart-grid locations. The aggregation reduces a distribution network having thousands of nodes to an equivalent network with a few aggregated nodes, thereby enabling distribution...... approaches is proposed to practically deploy the aggregated flexibility. The proposed method serves as a great operational tool for DSOs to decide the exact amount of required flexibilities from different network section(s) for solving grid constraint violations. The effectiveness of the proposed method...

  11. A BAYESIAN HIERARCHICAL SPATIAL MODEL FOR DENTAL CARIES ASSESSMENT USING NON-GAUSSIAN MARKOV RANDOM FIELDS.

    Science.gov (United States)

    Jin, Ick Hoon; Yuan, Ying; Bandyopadhyay, Dipankar

    2016-01-01

    Research in dental caries generates data with two levels of hierarchy: that of a tooth overall and that of the different surfaces of the tooth. The outcomes often exhibit spatial referencing among neighboring teeth and surfaces, i.e., the disease status of a tooth or surface might be influenced by the status of a set of proximal teeth/surfaces. Assessments of dental caries (tooth decay) at the tooth level yield binary outcomes indicating the presence/absence of teeth, and trinary outcomes at the surface level indicating healthy, decayed, or filled surfaces. The presence of these mixed discrete responses complicates the data analysis under a unified framework. To mitigate complications, we develop a Bayesian two-level hierarchical model under suitable (spatial) Markov random field assumptions that accommodates the natural hierarchy within the mixed responses. At the first level, we utilize an autologistic model to accommodate the spatial dependence for the tooth-level binary outcomes. For the second level and conditioned on a tooth being non-missing, we utilize a Potts model to accommodate the spatial referencing for the surface-level trinary outcomes. The regression models at both levels were controlled for plausible covariates (risk factors) of caries, and remain connected through shared parameters. To tackle the computational challenges in our Bayesian estimation scheme caused due to the doubly-intractable normalizing constant, we employ a double Metropolis-Hastings sampler. We compare and contrast our model performances to the standard non-spatial (naive) model using a small simulation study, and illustrate via an application to a clinical dataset on dental caries.

  12. 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.

  13. Spatial distribution of phytoplankton in the Gulf of Riga during spring and summer stages

    Science.gov (United States)

    Seppälä, J.; Balode, M.

    1999-12-01

    Distribution patterns of chlorophyll a, phytoplankton species and biomass were studied in the Gulf of Riga, one of the most eutrophicated areas of the Baltic Sea. Quasi-synoptic measurements were carried out during four seasonal stages (spring bloom 1995, early-summer stage 1994, cyanobacterial bloom 1994, and late summer stage 1993). For each stage, common factor analysis was used to simplify the highly correlated patterns of nutrients, salinity, temperature and the depth of mixed layer. Obtained latent variables were used to explain spatial distribution of phytoplankton. Generally, the distribution of phytoplankton variables followed closely the patterns of nutrient rich fresh water. During the spring bloom in 1995, the spatial structures of phytoplankton biomass (4-27 mg l -1) and chlorophyll a (13-50 μg l -1) were well explained ( r=0.68 and 0.69, respectively, pcryptomonads (on the average 50% of total biomass). At that stage the distribution of phytoplankton was obviously governed by biological interactions and the multivariate methods were not especially successful to explain the spatial distribution of the main components of phytoplankton community. Excluding the late summer phase, the statistical methods used in this study revealed well the relationships between phytoplankton variables and nutrient rich fresh water. It is evident that nutrient load from the River Daugava is a reason for higher phytoplankton biomass in the southern Gulf of Riga, especially during bloom occasions.

  14. Fractal spatial distribution of pancreatic islets in three dimensions: a self-avoiding growth model

    Science.gov (United States)

    Jo, Junghyo; Hörnblad, Andreas; Kilimnik, German; Hara, Manami; Ahlgren, Ulf; Periwal, Vipul

    2013-01-01

    The islets of Langerhans, responsible for controlling blood glucose levels, are dispersed within the pancreas. A universal power law governing the fractal spatial distribution of islets in two-dimensional pancreatic sections has been reported. However, the fractal geometry in the actual three-dimensional pancreas volume, and the developmental process that gives rise to such a self-similar structure, have not been investigated. Here, we examined the three-dimensional spatial distribution of islets in intact mouse pancreata using optical projection tomography and found a power law with a fractal dimension, 2.1. Furthermore, based on two-dimensional pancreatic sections of human autopsies, we found that the distribution of human islets also follows a universal power law with fractal dimension 1.5 in adult pancreata, which agrees with the value previously reported in smaller mammalian pancreas sections. Finally, we developed a self-avoiding growth model for the development of the islet distribution and found that the fractal nature of the spatial islet distribution may be associated with the self-avoidance in the branching process of vascularization in the pancreas. PMID:23629025

  15. Population dynamics and spatial distribution of Abaris basistriata Chaudoir, 1873 (Coleoptera: Carabidae

    Directory of Open Access Journals (Sweden)

    Ivan Carlos Fernandes Martins

    2016-02-01

    Full Text Available ABSTRACT Abaris basistriata, a beetle species dominant in agroecosystems and natural habitats, may benefit from the establishment of nearby refuge areas or crop field centers. To confirm this hypothesis, we analyzed the spatial distribution of the species and verified the population dynamics of this predator in a soybean/corn rotation crop and a central refuge area. The 1-ha experimental area was divided in half by a range of herbaceous plants (2 m in width and 80 m in length. Beetle samples were collected using pitfall traps every fortnight during the in-season and every month during the off-season (a total of 27 sampling occurrences. Population fluctuation was analyzed by correlating the total number of specimens with plant phenology. We used multiple regression analysis with variable (stepwise selection to examine the influence of meteorological factors on species occurrence. To determine the spatial distribution, data were analyzed using dispersion indices and probabilistic models based on the Coleoptera frequency distribution. Distribution visualization was assessed using a linear interpolation map. A total of 143 A. basistriata specimens were collected, with 83 from the soybean/corn area and 60 from the refuge area. Periods of large population size occurred during a season with high rainfall and high maximum and minimum temperatures. On the basis of the spatial distribution analysis of A. basistriata, it is likely that the beetles occur in an aggregate form, preferably in the refuge area.

  16. 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.

  17. Limit distributions for queues and random rooted trees

    Directory of Open Access Journals (Sweden)

    Lajos Takács

    1993-01-01

    Full Text Available In this paper several limit theorems are proved for the fluctuations of the queue size during the initial busy period of a queuing process with one server. These theorems are used to find the solutions of various problems connected with the heights and widths of random rooted trees.

  18. Stimulated luminescence emission from localized recombination in randomly distributed defects

    DEFF Research Database (Denmark)

    Jain, Mayank; Guralnik, Benny; Andersen, Martin Thalbitzer

    2012-01-01

    results in a highly asymmetric TL peak; this peak can be understood to derive from a continuum of several first-order TL peaks. Our model also shows an extended power law behaviour for OSL (or prompt luminescence), which is expected from localized recombination mechanisms in materials with random...

  19. 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

  20. A high-resolution modelling approach on spatial wildfire distribution in the Tyrolean Alps

    Science.gov (United States)

    Malowerschnig, Bodo; Sass, Oliver

    2013-04-01

    Global warming will cause increasing danger of wildfires in Austria, which can have long-lasting consequences on woodland ecosystems. The protective effect of forest can be severely diminished, leading to natural hazards like avalanches and rockfall. However, data on wildfire frequency and distribution have been sparse and incomplete for Austria. Long-lasting postfire degradation under adverse preconditions (steep slopes, limestone) was a common phenomenon in parts of the Tyrolean Alps several decades ago and should become relevant again under a changing fire frequency. The FIRIA project compiles historical wildfire data, information on fuel loads, fire weather indices (FWI) and vegetation recovery patterns. The governing climatic, topographic and socio-economic factors of forest fire distribution were assessed to trigger a distribution model of currently fire-prone areas in Tyrol. By collecting data from different sources like old newspapers archives and fire-fighter databases, we were able to build up a fire database of wildfire occurrences containing more than 1400 forest fires since the 15th century in Tyrol. For the period from 1993 to 2011, the database is widely complete and covers 482 fires. Using a non-parametrical statistical method it was possible to select the best suited fire weather index (FWI) for the prediction. The testing of 19 FWI's shows that it is necessary to use two discriminative indices to differentiate between summer and winter season. Together with compiled topographic, socio-economic, infrastructure and forest maps, the dataset was the base for a multifactorial analysis, performed by comparing the maximum entropy approach (Maxent) with an ensemble classifier (Random Forests). Both approaches have their background in the spatial habitat distribution and are easy to adapt to the requirements of a wildfire ignition model. The aim of this modelling approach was to determine areas which are particularly prone to wildfire. Due to the

  1. Lack of Correlation Between the Spatial Distribution of A2E and Lipofuscin Fluorescence in the Human Retinal Pigment Epithelium

    OpenAIRE

    Ablonczy, Zsolt; Higbee, Daniel; Anderson, David M.; Dahrouj, Mohammad; Grey, Angus C.; Gutierrez, Danielle; Koutalos, Yiannis; Schey, Kevin L.; Hanneken, Anne; Crouch, Rosalie K.

    2013-01-01

    This report to our knowledge is the first description of the spatial distribution of A2E in the human RPE at high resolution, which has allowed a direct comparison of A2E distribution with lipofuscin fluorescence.

  2. 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.

  3. Spatial and temporal distribution of carbon dioxide gas using GOSAT data over IRAN.

    Science.gov (United States)

    Falahatkar, Samereh; Mousavi, Seyed Mohsen; Farajzadeh, Manochehr

    2017-11-09

    CO2 concentration (XCO2) shows the spatial and temporal variation in Iran. The major purpose of this investigation is the assessment of the spatial distribution of carbon dioxide concentration in the different seasons of 2013 based on the Thermal And Near Infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) level 2 GOSAT data by implementing the ordinary kriging (OK) method. In this study, the Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI) data from the MODerate resolution Imaging Spectroradiometer (MODIS), and metrological parameters (temperature and precipitation) were used for the analysis of the spatial distribution of CO2 over Iran in 2013. The spatial distribution maps of XCO2 show the highest concentration of this gas in the south and south-east and the lowest concentration in the north and north-west. These results indicate that the concentration of carbon dioxide decreased with the increase of LST and temperature and a decrease of NDVI and humidity in the study area. Therefore, the existence of vegetation has an effective role in capturing carbon from the atmosphere by photosynthesis phenomena, and sustainable land management can be effective for carbon absorption from the atmosphere and mitigation of climate change in arid and semi-arid regions.

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

    Science.gov (United States)

    Ni, Jianhua; Qian, Tianlu; Xi, Changbai; Rui, Yikang; Wang, Jiechen

    2016-08-18

    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.

  6. 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.

  7. 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

  8. Spatial distribution of groundwater quality with special emphasis on fluoride of Mandvi Taluka, Surat, Gujarat, India

    Science.gov (United States)

    Prajapati, Mayuri; Jariwala, Namrata; Agnihotri, Prasit

    2017-12-01

    The present study deals with the groundwater quality with respect to F- in the Mandavi Taluka of Surat city with an objective to analyze the spatial variability of ground water quality parameter. A total 57 representative groundwater samples from different bore wells and hand pumps were collected during pre-monsoon. Samples were analyzed for various physiochemical parameters including fluoride. GIS technique is adopted to prepare DEM and spatial distribution map of fluoride to represent fluoride concentration in the study area. Results obtained from analysis with GIS mapping reveal that fluoride in the study is mainly attributed to geogenic source.

  9. High spatial resolution distributed optical fiber dynamic strain sensor with enhanced frequency and strain resolution.

    Science.gov (United States)

    Masoudi, Ali; Newson, Trevor P

    2017-01-15

    A distributed optical fiber dynamic strain sensor with high spatial and frequency resolution is demonstrated. The sensor, which uses the ϕ-OTDR interrogation technique, exhibited a higher sensitivity thanks to an improved optical arrangement and a new signal processing procedure. The proposed sensing system is capable of fully quantifying multiple dynamic perturbations along a 5 km long sensing fiber with a frequency and spatial resolution of 5 Hz and 50 cm, respectively. The strain resolution of the sensor was measured to be 40 nε.

  10. 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

  11. 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.

  12. Applications of Geographical Information Systems in Understanding Spatial Distribution of Asthma

    Directory of Open Access Journals (Sweden)

    Mohammad A. Rob

    2003-01-01

    Full Text Available Geographical Information Systems (GIS are becoming useful tools in making strategic decisions when-ever data are found to have spatial distribution. Federal, state, and local governments are using GIS for assessment and planning in such areas as housing, healthcare, land use, natural resources, environmental monitoring and transportation. Companies are also using it to expand and consolidate existing businesses, perform market analysis, and to find optimum delivery routes. In this paper, we illustrate the usefulness of GIS in the analysis and presentation of spatially distributed asthma prevalence among school children (13-17 years in the New York City area. To the best of our knowledge, this is the first presentation of asthma survey results distributed over the zip codes of a large city. Preliminary results show good correlation between asthma and poverty. They also correlate well with the spatial distribution of asthma hospitalization data. Results reveal an overall asthma prevalence of ~ 16% as compared to the national average of ~12% for a similar age group (5-17 years. When comparing asthma rates among the predominant racial groups of the city - Blacks and Hispanics are found to have a higher prevalence than Whites or Asians. The inner-city population shows a significantly higher asthma prevalence than those in the suburbs. This study shows our understanding of asthma prevalence in a dimension that could not have been possible prior to the availability of GIS. The results will help us making further decisions in planning for asthma research.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. The spatial distribution of known predictors of autism spectrum disorders impacts geographic variability in prevalence in central North Carolina

    Directory of Open Access Journals (Sweden)

    Hoffman Kate

    2012-10-01

    Full Text Available Abstract Background The causes of autism spectrum disorders (ASD remain largely unknown and widely debated; however, evidence increasingly points to the importance of environmental exposures. A growing number of studies use geographic variability in ASD prevalence or exposure patterns to investigate the association between environmental factors and ASD. However, differences in the geographic distribution of established risk and predictive factors for ASD, such as maternal education or age, can interfere with investigations of ASD etiology. We evaluated geographic variability in the prevalence of ASD in central North Carolina and the impact of spatial confounding by known risk and predictive factors. Methods Children meeting a standardized case definition for ASD at 8 years of age were identified through records-based surveillance for 8 counties biennially from 2002 to 2008 (n=532. Vital records were used to identify the underlying cohort (15% random sample of children born in the same years as children with an ASD, n=11,034, and to obtain birth addresses. We used generalized additive models (GAMs to estimate the prevalence of ASD across the region by smoothing latitude and longitude. GAMs, unlike methods used in previous spatial analyses of ASD, allow for extensive adjustment of individual-level risk factors (e.g. maternal age and education when evaluating spatial variability of disease prevalence. Results Unadjusted maps revealed geographic variation in surveillance-recognized ASD. Children born in certain regions of the study area were up to 1.27 times as likely to be recognized as having ASD compared to children born in the study area as a whole (prevalence ratio (PR range across the study area 0.57-1.27; global P=0.003. However, geographic gradients of ASD prevalence were attenuated after adjusting for spatial confounders (adjusted PR range 0.72-1.12 across the study area; global P=0.052. Conclusions In these data, spatial variation of ASD

  18. 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.

  19. Spatial Distributions of HIV Infection in an Endemic Area of Western Kenya: Guiding Information for Localized HIV Control and Prevention.

    Directory of Open Access Journals (Sweden)

    Tomonori Hoshi

    Full Text Available HIV is still a major health problem in developing countries. Even though high HIV-risk-taking behaviors have been reported in African fishing villages, local distribution patterns of HIV infection in the communities surrounding these villages have not been thoroughly analyzed. The objective of this study was to investigate the geographical distribution patterns of HIV infection in communities surrounding African fishing villages. In 2011, we applied age- and sex-stratified random sampling to collect 1,957 blood samples from 42,617 individuals registered in the Health and Demographic Surveillance System in Mbita, which is located on the shore of Lake Victoria in western Kenya. We used these samples to evaluate existing antibody detection assays for several infectious diseases, including HIV antibody titers. Based on the results of the assays, we evaluated the prevalence of HIV infection according to sex, age, and altitude of participating households. We also used Kulldorff's spatial scan statistic to test for HIV clustering in the study area. The prevalence of HIV at our study site was 25.3%. Compared with the younger age group (15-19 years, adults aged 30-34 years were 6.71 times more likely to be HIV-positive, and the estimated HIV-positive population among women was 1.43 times larger than among men. Kulldorff's spatial scan statistic detected one marginally significant (P = 0.055 HIV-positive and one significant HIV-negative cluster (P = 0.047 in the study area. These results suggest a homogeneous HIV distribution in the communities surrounding fishing villages. In addition to individual behavior, more complex and diverse factors related to the social and cultural environment can contribute to a homogeneous distribution pattern of HIV infection outside of African fishing villages. To reduce rates of transmission in HIV-endemic areas, HIV prevention and control programs optimized for the local environment need to be developed.

  20. Spatial Distribution of Reef Fish Species along the Southeast US Atlantic Coast Inferred from Underwater Video Survey Data.

    Directory of Open Access Journals (Sweden)

    Nathan M Bacheler

    Full Text Available Marine fish abundance and distribution often varies across spatial scales for a variety of reasons, and this variability has significant ecological and management consequences. We quantified the distribution of reef-associated fish species along the southeast United States Atlantic coast using underwater video survey samples (N = 4,855 in 2011-2014 to elucidate variability within species across space, depths, and habitats, as well as describe broad-scale patterns in species richness. Thirty-two species were seen at least 10 times on video, and the most commonly observed species were red porgy (Pagrus pagrus; 41.4% of videos, gray triggerfish (Balistes capriscus; 31.0%, black sea bass (Centropristis striata; 29.1%, vermilion snapper (Rhomboplites aurorubens; 27.7%, and red snapper (Lutjanus campechanus; 22.6%. Using generalized additive models, we found that most species were non-randomly distributed across space, depths, and habitats. Most rare species were observed along the continental shelf break, except for goliath grouper (Epinephelus itajara, which was found on the continental shelf in Florida and Georgia. We also observed higher numbers of species in shelf-break habitats from southern North Carolina to Georgia, and fewer in shallower water and at the northern and southern ends of the southeast United States Atlantic coast. Our study provides the first broad-scale description of the spatial distribution of reef fish in the region to be based on fishery-independent data, reinforces the utility of underwater video to survey reef fish, and can help improve the management of reef fish in the SEUS, for example, by improving indices of abundance.

  1. 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 and distribution of suitable nesting trees influences the variability of colony size and spatial distribution of colonies in two study sites in the Kalahari, South Africa. We used spatial statistics to describe characteristics of point patterns. Nests of communal...

  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. Sparse Maximum-Entropy Random Graphs with a Given Power-Law Degree Distribution

    Science.gov (United States)

    van der Hoorn, Pim; Lippner, Gabor; Krioukov, Dmitri

    2017-10-01

    Even though power-law or close-to-power-law degree distributions are ubiquitously observed in a great variety of large real networks, the mathematically satisfactory treatment of random power-law graphs satisfying basic statistical requirements of realism is still lacking. These requirements are: sparsity, exchangeability, projectivity, and unbiasedness. The last requirement states that entropy of the graph ensemble must be maximized under the degree distribution constraints. Here we prove that the hypersoft configuration model, belonging to the class of random graphs with latent hyperparameters, also known as inhomogeneous random graphs or W-random graphs, is an ensemble of random power-law graphs that are sparse, unbiased, and either exchangeable or projective. The proof of their unbiasedness relies on generalized graphons, and on mapping the problem of maximization of the normalized Gibbs entropy of a random graph ensemble, to the graphon entropy maximization problem, showing that the two entropies converge to each other in the large-graph limit.

  4. Interactions Among Spatial Scales Constrain Species Distributions in Fragmented Urban Landscapes

    Directory of Open Access Journals (Sweden)

    Will R. Turner

    2006-12-01

    Full Text Available Understanding species' responses to habitat loss is a major challenge for ecologists and conservation biologists, who need quantitative, yet practical, frameworks to design landscapes better able to sustain native species. I here develop one such framework by synthesizing two ecological paradigms: scale-dependence and constraint-like interactions in biological phenomena. I develop a model and apply it to birds around Tucson, USA, investigating the manner in which spatial scales interact to constrain species distributions in fragmented urban landscapes. Species' responses vary in interesting ways. Surprisingly, most show situations in which habitat at one spatial scale constrains the influence of habitat at another scale. I discuss the implications of this work for conservation in human-dominated landscapes, and the need to recognize constraint-like interactions among processes and spatial scales in ecology.

  5. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    Science.gov (United States)

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-01-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface. PMID:28195131

  6. 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

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

    NARCIS (Netherlands)

    E. Fisher (Eric); D. Pahan (David); S. Chowdhury (Susmita); J.H. Richardus (Jan Hendrik)

    2008-01-01

    textabstractBACKGROUND: 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

  8. 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.

  9. Spatial distribution of oak mistletoe as it relates to habits of oak woodland frugivores.

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    Ethan A Wilson

    Full Text Available This study addresses the underlying spatial distribution of oak mistletoe, Phoradendron villosum, a hemi-parasitic plant that provides a continuous supply of berries for frugivorous birds overwintering the oak savanna habitat of California's outer coast range. As the winter community of birds consuming oak mistletoe varies from group-living territorial species to birds that roam in flocks, we asked if mistletoe volume was spatially autocorrelated at the scale of persistent territories or whether the patterns predicted by long-term territory use by western bluebirds are overcome by seed dispersal by more mobile bird species. The abundance of mistletoe was mapped on trees within a 700 ha study site in Carmel Valley, California. Spatial autocorrelation of mistletoe volume was analyzed using the variogram method and spatial distribution of oak mistletoe trees was analyzed using Ripley's K and O-ring statistics. On a separate set of 45 trees, mistletoe volume was highly correlated with the volume of female, fruit-bearing plants, indicating that overall mistletoe volume is a good predictor of fruit availability. Variogram analysis showed that mistletoe volume was spatially autocorrelated up to approximately 250 m, a distance consistent with persistent territoriality of western bluebirds and philopatry of sons, which often breed next door to their parents and are more likely to remain home when their parents have abundant mistletoe. Using Ripley's K and O-ring analyses, we showed that mistletoe trees were aggregated for distances up to 558 m, but for distances between 558 to 724 m the O-ring analysis deviated from Ripley's K in showing repulsion rather than aggregation. While trees with mistletoe were aggregated at larger distances, mistletoe was spatially correlated at a smaller distance, consistent with what is expected based on persistent group territoriality of western bluebirds in winter and the extreme philopatry of their sons.

  10. Spatial distribution of oak mistletoe as it relates to habits of oak woodland frugivores.

    Science.gov (United States)

    Wilson, Ethan A; Sullivan, Patrick J; Dickinson, Janis L

    2014-01-01

    This study addresses the underlying spatial distribution of oak mistletoe, Phoradendron villosum, a hemi-parasitic plant that provides a continuous supply of berries for frugivorous birds overwintering the oak savanna habitat of California's outer coast range. As the winter community of birds consuming oak mistletoe varies from group-living territorial species to birds that roam in flocks, we asked if mistletoe volume was spatially autocorrelated at the scale of persistent territories or whether the patterns predicted by long-term territory use by western bluebirds are overcome by seed dispersal by more mobile bird species. The abundance of mistletoe was mapped on trees within a 700 ha study site in Carmel Valley, California. Spatial autocorrelation of mistletoe volume was analyzed using the variogram method and spatial distribution of oak mistletoe trees was analyzed using Ripley's K and O-ring statistics. On a separate set of 45 trees, mistletoe volume was highly correlated with the volume of female, fruit-bearing plants, indicating that overall mistletoe volume is a good predictor of fruit availability. Variogram analysis showed that mistletoe volume was spatially autocorrelated up to approximately 250 m, a distance consistent with persistent territoriality of western bluebirds and philopatry of sons, which often breed next door to their parents and are more likely to remain home when their parents have abundant mistletoe. Using Ripley's K and O-ring analyses, we showed that mistletoe trees were aggregated for distances up to 558 m, but for distances between 558 to 724 m the O-ring analysis deviated from Ripley's K in showing repulsion rather than aggregation. While trees with mistletoe were aggregated at larger distances, mistletoe was spatially correlated at a smaller distance, consistent with what is expected based on persistent group territoriality of western bluebirds in winter and the extreme philopatry of their sons.

  11. 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

  12. Regular and Chaotic Spatial Distribution of Bose-Einstein Condensed Atoms in a Ratchet Potential

    Science.gov (United States)

    Li, Fei; Xu, Lan; Li, Wenwu

    2018-02-01

    We study the regular and chaotic spatial distribution of Bose-Einstein condensed atoms with a space-dependent nonlinear interaction in a ratchet potential. There exists in the system a space-dependent atomic current that can be tuned via Feshbach resonance technique. In the presence of the space-dependent atomic current and a weak ratchet potential, the Smale-horseshoe chaos is studied and the Melnikov chaotic criterion is obtained. Numerical simulations show that the ratio between the intensities of optical potentials forming the ratchet potential, the wave vector of the laser producing the ratchet potential or the wave vector of the modulating laser can be chosen as the controlling parameters to result in or avoid chaotic spatial distributional states.

  13. A study of temperature's spatial distribution in Neuquen River valley through satellite imaging

    Directory of Open Access Journals (Sweden)

    Marisa Gloria Cogliati

    2010-01-01

    Full Text Available This paper looks into the spatial distribution of brightness and surface temperature through the use of LAND SAT7 ETM+ and NO AA-AVHRR satellite imagery in the cultivated valley of the Neuquén river. Studying the spatial distribution of temperatures in an area with a somewhat complex terrain requires the use of a great density of meteorological measurements. It is often impossible to obtain the right density of the argometeorological network due to the high installation and maintenance costs. Remote sensors provide a large flow of information in various resolutions, at considerably lower costs. Determining the valley's warm and cold zones would allow for more efficient irrigation and frost-protection methods, and it would provide tools to improve the area's productive planning.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    The classical Wells-Riley model for predicting risk of airborne transmission of diseases assumes a uniform spatial distribution of the infected cases in an enclosed space. A new mathematical model is developed here for predicting the spatial distribution of infection risk of airborne transmitted...... diseases by integrating the Wells-Riley equation into computational fluid dynamics. We applied our new integrated model to analyze a large nosocomial SARS outbreak in Hong Kong during the 2003 SARS epidemics, which was studied in the literature with regard to the association between airflow and SARS...... infection. The predicted numbers of infected cases of medical students in the same cubicle, the adjacent cubicle and the distant cubicle were 6.39, 0.78 and 0.2 respectively while the observed numbers of infected medical students in the three cubicles were 7, 0 and 0 respectively during the morning of March...

  15. 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.

  16. 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.

  17. Spatially and temporally resolved gas distributions around heterogeneous catalysts using infrared planar laser-induced fluorescence

    Science.gov (United States)

    Zetterberg, Johan; Blomberg, Sara; Gustafson, Johan; Evertsson, Jonas; Zhou, Jianfeng; Adams, Emma C.; Carlsson, Per-Anders; Aldén, Marcus; Lundgren, Edvin

    2015-01-01

    Visualizing and measuring the gas distribution in close proximity to a working catalyst is crucial for understanding how the catalytic activity depends on the structure of the catalyst. However, existing methods are not able to fully determine the gas distribution during a catalytic process. Here we report on how the distribution of a gas during a catalytic reaction can be imaged in situ with high spatial (400 μm) and temporal (15 μs) resolution using infrared planar laser-induced fluorescence. The technique is demonstrated by monitoring, in real-time, the distribution of carbon dioxide during catalytic oxidation of carbon monoxide above powder catalysts. Furthermore, we demonstrate the versatility and potential of the technique in catalysis research by providing a proof-of-principle demonstration of how the activity of several catalysts can be measured simultaneously, either in the same reactor chamber, or in parallel, in different reactor tubes. PMID:25953006

  18. 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.

  19. Spatial analysis of Neospora caninum distribution in dairy cattle from Sweden

    Directory of Open Access Journals (Sweden)

    Jenny Frössling

    2008-11-01

    Full Text Available The national herd prevalence and spatial distribution of Neospora caninum infected dairy herds in Sweden were investigated. The study was based on a bulk milk survey comprising samples from 2,978 herds. Test-positive herds were found in all parts of Sweden and the overall prevalence of test-positive herds was 8.3% (95% confidence interval = 7.3-9.3%. The presence of spatial autocorrelation was tested using the Moran’s I test. Possible clusters of test-positive herds were identified by applying the local indicator of spatial association (LISA test statistic and the spatial scan statistic. Analysis based on data aggregated by postal code areas as well as analysis based on exact coordinates identified significant clusters of high prevalence in the middle parts of Sweden and low prevalence in the south. This was not expected considering the results from other European studies of N. caninum in cattle. However, the findings are supported by the distribution of previously known case herds.

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

    Directory of Open Access Journals (Sweden)

    Claire Saraux

    Full Text Available Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean, sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than anchovies. The spatial structure of the three species was fairly stable over time according to variogram outputs, while year-to-year variations in kriged maps highlighted substantial changes in their location. Support for the McCall's basin hypothesis (covariation of both population density and presence area with biomass was found only in sprats, the most variable of the three species. An innovative method to investigate species collocation at different scales revealed that globally the three species strongly overlap. Although species often co-occurred in terms of presence/absence, their biomass density differed at local scale, suggesting potential interspecific avoidance or different sensitivity to local environmental characteristics. Persistent favourable areas were finally detected, but their environmental characteristics remain to be determined.

  1. Spatial Distribution of Tropospheric Ozone in National Parks of California: Interpretation of Passive-Sampler Data

    Directory of Open Access Journals (Sweden)

    John D. Ray

    2001-01-01

    Full Text Available The National Park Service (NPS has tested and used passive ozone samplers for several years to get baseline values for parks and to determine the spatial variability within parks. Experience has shown that the Ogawa passive samplers can provide ±10% accuracy when used with a quality assurance program consisting of blanks, duplicates, collocated instrumentation, and a standard operating procedure that carefully guides site operators. Although the passive device does not meet EPA criteria as a certified method (mainly, that hourly values be measured, it does provide seasonal summed values of ozone. The seasonal ozone concentrations from the passive devices can be compared to other monitoring to determine baseline values, trends, and spatial variations. This point is illustrated with some kriged interpolation maps of ozone statistics. Passive ozone samplers were used to get elevational gradients and spatial distributions of ozone within a park. This was done in varying degrees at Mount Rainier, Olympic, Sequoia–Kings Canyon, Yosemite, Joshua Tree, Rocky Mountain, and Great Smoky Mountains national parks. The ozone has been found to vary by factors of 2 and 3 within a park when average ozone is compared between locations. Specific examples of the spatial distributions of ozone in three parks within California are given using interpolation maps. Positive aspects and limitations of the passive sampling approach are presented.

  2. Spatial distribution of fish assemblages along environmental gradients in the temporary ponds of Northern Pantanal, Brazil

    Directory of Open Access Journals (Sweden)

    Karina K. Tondato

    2013-02-01

    Full Text Available Ten temporary ponds in northern Pantanal were studied in July 2006 to explore whether a spatial distribution pattern existed in the composition of fish assemblages, and to identify which environmental variables determined their distribution. The existence of any spatial pattern was tested using the multivariate Mantel correlogram, while the influence of environmental variables was quantified by a Canonical Correspondence Analysis (CCA. A total of 8735 individuals was sampled from 29 species, predominantly represented by Hyphessobrycon elachys and Serrapinnus calliurus. Composition of fish assemblages varied among ponds, but this variation had no significant spatial pattern for any of the distance classes considered, thus indicating that the species composition varied independently of the distance between ponds. This suggests that stochastic dispersal processes did not influence the spatial structure of species, as predicted by the neutral theory. Conversely, species composition in the ponds was determined by variables that included depth, macrophyte richness and cover. Species such as Markiana nigripinnis, Crenicichla vittata and Moenkhausia sanctaefilomenae occurred in deeper waters, while Parauchenipterus striatulus, Eigenmannia trilineata and Psellogrammus kennedyi were mainly associated with greater richness and macrophyte cover, as already demonstrated by the niche theory applied in ponds which tended to have similar characteristics and a similar fish composition.

  3. Reproducibility of spatial and temporal distribution of aseismic slips in Hyuga-nada of southwest Japan

    Science.gov (United States)

    Nakata, Ryoko; Miyazaki, Shin'ichi; Hyodo, Mamoru; Hori, Takane

    2014-09-01

    The Hyuga-nada region of southwest Japan, which is located off the east coast of Kyushu Island, may have the potential to generate great interplate earthquakes along the Nankai trough in the future. In this area, thrust earthquakes of M = 6.7-7.2 have occurred with recurrence intervals of approximately 30 years. In association with these earthquakes, possible local heterogeneities of plate coupling may be expected within 100 km from the coast in the Hyuga-nada region. We investigate numerical experiments to determine the spatial and temporal resolution of slip on the plate interface beneath the Hyuga-nada offshore region. For this purpose, we calculated synthetic displacement data from the result of numerical simulation conducted for the afterslip following an Mw 6.8 earthquake, for existing global positioning system stations on land and planned ocean floor seismic network stations. The spatial and temporal distribution of fault slip is then estimated using a Kalman filter-based inversion. The slip distribution estimated by using ocean floor stations demonstrates that the heterogeneity of plate coupling is resolved approximately within 50 km from the coastal area. This heterogeneity corresponds to the coseismic area of an Mw 6.8 earthquake with a radius of 10 km. Our study quantitatively evaluates the spatial resolution of aseismic slip in the Hyuga-nada region. Analysis based on continuous ocean floor data is useful for resolving the spatial variations of heterogeneities in plate couplings.

  4. Review and possible development direction of the methods for modeling of soil pollutants spatial distribution

    Science.gov (United States)

    Tarasov, D. A.; Medvedev, A. N.; Sergeev, A. P.; Buevich, A. G.

    2017-07-01

    Forecasting of environmental pollutants spatial distribution is a significant field of research in view of the current concerns regarding environment all over the world. Due to the danger to health and environment associated with an increase in pollution of air, soil, water and biosphere, it is very important to have the models that are capable to describe the modern distribution of contaminants and to forecast the dynamic of their spreading in future at different territories. This article addresses the methods, which applied the most often in this field, with an accent on soil pollution. The possible direction of such methods further development is suggested.

  5. 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 gradients present challenges for process development and scale up [1]. Heterogeneities in substrate concentration have been identified in large scale fermenters [2] and reliable tools to identify and quantify these phenomena are required. This work utilizes the degradation of hydrogen peroxide to oxygen...... by catalase to illustrate and validate how substrate is distributed throughout the vessel by combining CFD and experimental data collected with spatially distributed sensors....

  6. Impact of microwave derived soil moisture on hydrologic simulations using a spatially distributed water balance model

    Science.gov (United States)

    Lin, D. S.; Wood, E. F.; Famiglietti, J. S.; Mancini, M.

    1994-01-01

    Spatial distributions of soil moisture over an agricultural watershed with a drainage area of 60 ha were derived from two NASA microwave remote sensors, and then used as a feedback to determine the initial condition for a distributed water balance model. Simulated hydrologic fluxes over a period of twelve days were compared with field observations and with model predictions based on a streamflow derived initial condition. The results indicated that even the low resolution remotely sensed data can improve the hydrologic model's performance in simulating the dynamics of unsaturated zone soil moisture. For the particular watershed under study, the simulated water budget was not sensitive to the resolutions of the microwave sensors.

  7. Topographic and spatial controls of palm species distributions in a montane rain forest, southern Ecuador

    DEFF Research Database (Denmark)

    Svenning, J.-C.; Harlev, D.; Sørensen, M.M.

    2009-01-01

    to elevational gradients in climate has been emphasized as a driver of vegetation distribution and plant community assembly in tropical mountain areas such as the Andes for two centuries, while alternative mechanisms have been little studied. Here, we investigated the importance of topography and spatial...... distributions at the study site. Other factors must also be involved, notably wind-exposure and hydrology, as discussed for lowland palm communities. Our results show that to understand plant community assembly in the tropical montane forests of the Andes it is too simple to focus just on environmental sorting...

  8. Spatial and temporal distribution of Pacific cod Gadus macrocephalus juveniles in Mutsu Bay, Japan

    OpenAIRE

    Takatsu, Tetsuya; Yoshida, Yasuyuki; Kooka, Kouji; Sugimoto, Kouichi; Takahashi, Toyomi

    2001-01-01

    The spatial distributions of Pacific cod (Gadus macrocephalus) juveniles and their food organisms were examined in Mutsu Bay from April to July during 1988-1997. In April, large larvae (≤25 mm in total length (TL)) and pelagic juveniles (>25 mm TL) were widely distributed in the bay, and were concentrated at the same depths as calanoid copepodites during daylight hours. Geographical changes in cod TLs might have been due to transport by the Tsugaru Warm Current. After mid- and late May, juven...

  9. Factors controlling spatial distribution patterns of biocrusts in a heterogeneous and topographically complex semiarid area

    Science.gov (United States)

    Chamizo, Sonia; Rodríguez-Caballero, Emilio; Roncero, Beatriz; Raúl Román, José; Cantón, Yolanda

    2016-04-01

    Biocrusts are widespread soil components in drylands all over the world. They are known to play key roles in the functioning of these regions by fixing carbon and nitrogen, regulating hydrological processes, and preventing from water and wind erosion, thus reducing the loss of soil resources and increasing soil fertility. The rate and magnitude of services provided by biocrusts greatly depend on their composition and developmental stage. Late-successional biocrusts such as lichens and mosses have higher carbon and nitrogen fixation rates, and confer greater protection against erosion and the loss of sediments and nutrients than early-successional algae and cyanobacteria biocrusts. Knowledge of spatial distribution patterns of different biocrust types and the factors that control their distribution is important to assess ecosystem services provided by biocrusts at large spatial scales and to improve modelling of biogeochemical processes and water and carbon balance in drylands. Some of the factors that condition biocrust cover and composition are incoming solar radiation, terrain attributes, vegetation distribution patterns, microclimatic variables and soil properties such as soil pH, texture, soil organic matter, soil nutrients and gypsum and CaCO3 content. However, the factors that govern biocrust distribution may vary from one site to another depending on site characteristics. In this study, we examined the influence of abiotic attributes on the spatial distribution of biocrust types in a complex heterogeneous badland system (Tabernas, SE Spain) where biocrust cover up to 50% of the soil surface. From the analysis of relationships between terrain attributes and proportional abundance of biocrust types, it was found that topography exerted a main control on the spatial distribution of biocrust types in this area. SW-facing slopes were dominated by physical soil crusts and were practically devoid of vegetation and biocrusts. Biocrusts mainly occupied the pediments

  10. Spatial Distribution of Voids in Insulating Concrete Analyzed by Micro-CT Images and Probability Functions

    Directory of Open Access Journals (Sweden)

    Sang-Yeop Chung

    2015-01-01

    Full Text Available Insulating concrete is a multiphase material designed for reduced thermal conductivity, and the void distribution in concrete strongly affects its physical properties such as mechanical response and heat conduction. Therefore, it is essential to develop a method for identifying the spatial distribution of voids. To examine the voids of insulating concrete specimens, micro-CT (computed tomography images can be effectively used. The micro-CT images are binarized to visualize the void distribution and stacked to generate 3D specimen images. From the obtained images, the spatial distribution of the voids and the microscopic constituents inside the insulating concrete specimens can be identified. The void distribution in the material can be characterized using low-order probability functions such as two-point correlation, lineal-path, and two-point cluster functions. It is confirmed that micro-CT images and low-order probability functions are effective in describing the relative degree of void clustering and void connectivity in insulating concrete.

  11. Uncertainty assessment of spatially distributed nitrate reduction potential in groundwater using multiple geological realizations

    Science.gov (United States)

    Hansen, A. L.; Gunderman, D.; He, X.; Refsgaard, J. C.

    2014-11-01

    Spatially distributed nitrate reduction potential in groundwater was estimated for the clay till dominated Norsminde fjord catchment in Denmark using the distributed hydrological model MIKE SHE. The nitrate transport was simulated using particle tracking and nitrate was assumed to be instantaneously reduced at the redox interface. Spatially distributed depths of the redox interface were estimated based on the spatial patterns in groundwater recharge and sediment redox capacity. Uncertainty of the estimated nitrate reduction due to geological uncertainty was assessed using multiple geological realizations. The geological realizations were generated using the geostatistical software TProGS and either conditioned based on borehole data only or soft conditioned based on both borehole data and geophysical data. Finally an upscaling of the predicted nitrate reduction was done in order to evaluate the change in uncertainty with increasing scale. The study showed that the uncertainty (one standard deviation) of the estimated nitrate reduction potential (in percentage of nitrate input) on the original 100 m model scale was 25% if only using borehole data and 19% if combining the borehole data with geophysical data. The uncertainty on the model predictions decreased with increasing aggregation scale. The decrease in uncertainty was most apparent the first 500 m, where after the uncertainty started to level off. This scale corresponded well to the mean length of the sand units within the clay till. It is concluded that using geophysical data in combination with borehole data in generation of geological realizations can help decrease uncertainty on the estimated nitrate reduction and that the predictive capability of distributed models is constrained by the spatial resolution of key data such as geology.

  12. SPATIAL DISTRIBUTION OF LYMPHATIC FILARIASIS IN CROSS RIVER STATE, NIGERIA: A GEOGRAPHICAL INFORMATION SYSTEMS (GIS) STUDY

    OpenAIRE

    Ukpong, Iniodu George; John, Davison Mbere-obong

    2016-01-01

    Effective control efforts on Lymphatic filariasis (LF) are hindered by paucity of reliable data on spatial distribution of the disease. Aim: This study was aimed at mapping and describing the transmission pattern of lymphatic filariasis in order to identify high risk zones of infection in Cross River State (CRS), to guide intervention programmes. Method: An 8-year case record (2006-2013) of Lymphatic filariasis in the 18 local government areas (LGAs) of CRS was mapped using geographical infor...

  13. The spatial distribution of pet dogs and pet cats on the island of Ireland

    Science.gov (United States)

    2011-01-01

    Background There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland. Results In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas. Conclusions The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care. PMID:21663606

  14. 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.

  15. DIFET: DISTRIBUTED FEATURE EXTRACTION TOOL FOR HIGH SPATIAL RESOLUTION REMOTE SENSING IMAGES

    Directory of Open Access Journals (Sweden)

    S. Eken

    2017-11-01

    Full Text Available In this paper, we propose distributed feature extraction tool from high spatial resolution remote sensing images. Tool is based on Apache Hadoop framework and Hadoop Image Processing Interface. Two corner detection (Harris and Shi-Tomasi algorithms and five feature descriptors (SIFT, SURF, FAST, BRIEF, and ORB are considered. Robustness of the tool in the task of feature extraction from LandSat-8 imageries are evaluated in terms of horizontal scalability.

  16. 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.

  17. 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

  18. Segmentation of Aegean Fishing Fleet and Spatial Distribution of Fishing Capacity

    OpenAIRE

    Ilke Kosar Danisman

    2013-01-01

    The data on fishing fleet play an important role in fisheries management. It is an effective method that collection of reliable and regular data on fleet, and these data into information that is needed in terms of fleet management. In this study, it is demonstrated that the segmentation of the Aegean fishing fleet and fishing port based spatial distribution of fishing capacities concerning each fleet segment at the Aegean coast to improve fisheries management.

  19. The spatial distribution of pet dogs and pet cats on the island of Ireland

    OpenAIRE

    Downes, Martin J; Clegg, Tracy A; Collins, Daniel M; McGrath, Guy; More, Simon J

    2011-01-01

    Abstract Background There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This...

  20. 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.

  1. Spatial distribution of groundwater recharge and base flow: Assessment of controlling factors

    OpenAIRE

    Z. Zomlot; B. Verbeiren; M. Huysmans; Batelaan, O.

    2015-01-01

    Study focus: Groundwater is of strategic importance. The accurate estimation of groundwater recharge and assessing the fundamental controlling factors are therefore of utmost importance to protect groundwater systems. We used the spatially-distributed water-balance model WetSpass to estimate long-term average recharge in Flanders. We validated recharge rates with base flow estimates of 67 daily stream flow records using the hydrograph analyses. To this end we performed principal component ana...

  2. Hyperspectral Imaging of a Turbine Engine Exhaust Plume to Determine Radiance, Temperature, and Concentration Spatial Distributions

    Science.gov (United States)

    2009-03-01

    CONCENTRATION SPATIAL DISTRIBUTIONS Spencer J. Bowen, BS Captain, USAF Approved: Michael A. Marciniak , PhD (Chainnan) Date Glen P. Perram, PhD...the order of 1015 and 1017 molecules/cm3, respectively. v Acknowledgments I would like to thank my advisor, Dr. Michael Marciniak , for the...advice of my colleagues in room 210 B , I would probably have lost my mind. Thank you Neil, Mitch, Katie, and Brooke for keeping me sane and full of

  3. Do stones modify the spatial distribution of fire-induced soil water repellency? Preliminary data

    OpenAIRE

    J. García-Moreno; A.J. Gordillo-Rivero; Gil, J.; N.T. Jiménez-Morillo; J. Matix-Solera; F.A. González-Peñaloza; Granged, A.J.P.; G. Bárcenas-Moreno; P. Jiménez-Pinilla; Lozano, E; Jordán, A.; Zavala, L. M.

    2013-01-01

    Water repellency is a property of many fire-affected soils that contributes to delayed wetting rates and shows many hydrological and geomorphological consequences. Fire-induced soil water repellency (SWR) may be modulated by pre-fire soil and vegetation properties. Many studies have been carried out to investigate the relationship between SWR and these properties. But, to our knowledge, no studies have considered the effect of surface stones in the spatial distribution of fire-ind...

  4. The spatial distribution of pet dogs and pet cats on the island of Ireland.

    Science.gov (United States)

    Downes, Martin J; Clegg, Tracy A; Collins, Daniel M; McGrath, Guy; More, Simon J

    2011-06-10

    There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland. In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas. The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care.

  5. Temporal and spatial variations of water qualities and fish fauna distributions in the Kaname river, Japan

    Science.gov (United States)

    Terada, K.; Kitano, T.; Kutsumi, M.; Shimizu, K.

    2011-12-01

    Fish fauna distributions had been studied at many places and they indicated that the fish distributions were dramatically different depending on fish species and local environment such as water temperature, current, sediment parameters. But the relationships between water qualities and fish fauna distribution have not been understood well. In order to find physical and chemical environment factors which relate to the fish fauna distribution, we investigated the temporal and spatial change of water qualities and fish distributions in Kaname river, Japan. We measured both of physical (temperature, salinity, dissolved oxygen, Chl-a and turbidity) and chemical (nitrate, nitrite, ammonia, orthophosphoric and suspended solids) water parameters and surveyed the fish distribution. The field observations were conducted seasonally and check the season differences. Observation results showed that Gobiidae and Cyprinidae fishes live in the Kaname river and the distribution was clearly classified with the species. And also chemical water qualities were dramatically different by location. Especially the effects of sewage farms on water qualities were detected. This study will be contributory to reveal the relationships between fish fauna distribution and environmental parameters and it will lead to the ecological preservation.

  6. Computer simulation of random variables and vectors with arbitrary probability distribution laws

    Science.gov (United States)

    Bogdan, V. M.

    1981-01-01

    Assume that there is given an arbitrary n-dimensional probability distribution F. A recursive construction is found for a sequence of functions x sub 1 = f sub 1 (U sub 1, ..., U sub n), ..., x sub n = f sub n (U sub 1, ..., U sub n) such that if U sub 1, ..., U sub n are independent random variables having uniform distribution over the open interval (0,1), then the joint distribution of the variables x sub 1, ..., x sub n coincides with the distribution F. Since uniform independent random variables can be well simulated by means of a computer, this result allows one to simulate arbitrary n-random variables if their joint probability distribution is known.

  7. 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.

  8. [Spatial distribution of fig wasps in syconia of two monoecious Ficus sp].

    Science.gov (United States)

    Wang, Zhen-Ji; Li, Guo-Chang; Peng, Yan-Qiong; Yang, Da-Rong

    2012-04-01

    In addition to pollinator fig wasps, there are several non-pollinating fig wasps associated with monoecious Ficus sp. In order to understand how pollinator fig wasps and non-pollinating fig wasps are distributed across the same syconium, the spatial distribution of fig wasps associated with Ficus altissima and F. benjamina were compared using the pedicle lengths of galls containing each species. The results indicate that in Ficus altissima, the average pedicel length of galls containing Eupristina sp. is longer than that containing E. altissima. Average pedicel length of galls containing Sycobia sp., Micranisa ralianga and Sycoscapter sp. two did not show significant difference. The range of pedicel lengths of galls containing Sycobia sp., M. ralianga or Sycoscapter sp. two is narrower than that of galls containing E. altissima, indicating these non-pollinating fig wasps and pollinator have partially separated spatial niches. In F. benjamina, E. koningsbergeri was distributed in galls from the outer layer to inner layer, while most Walkerella sp. were found in outer layer galls, indicating E. koningsbergeri and Walkerella sp. have partially separated spatial niches.

  9. Analysis of spatial distribution of Tehran Metropolis urban services using models of urban planning

    Directory of Open Access Journals (Sweden)

    A. Lorestani

    2016-04-01

    Full Text Available The process of spatial distribution of urban services in order to provide equitable access to opportunities and reduced regional disparities, and earning the highest citizen satisfaction are among the main challenges facing urban management. This requires knowledge of the current status of spatial distribution of public services in the city, followed by optimal resource allocation under varying circumstances. This analytical-comparative study aimed to investigate the spatial distribution of urban public services, and rank different districts of Tehran in terms of benefiting from public services. To achieve this goal, quantitative models of planning, including factor analysis, composite Human Development Index, taxonomical model and standardization method were used. For the final ranking of districts of Tehran, the sum of numerical value of each district was calculated in four ways. Based on this method, districts 1, 3, 22, 12 and 6 were ranked first to fifth, and districts 13, 10, 8, 17 and 14 were ranked last, respectively. Using cluster analysis model, different districts of Tehran metropolis were clustered on the basis of numerical value of districts in the models used. Based on above-mentioned results, districts 1, 3, 12, 22, 6 and 21, with a final score of 66 and above, included in the first cluster and identified as over-developed districts; and districts 14, 10, 8 and 17, with a final score of 13 or less, included in the fifth cluster and identified as disadvantaged districts.

  10. [Spatial distribution of dead and vital bacteria in the native dental biofilm].

    Science.gov (United States)

    Ji, Ya-Kun; Ling, Jun-Qi

    2007-05-01

    To examine the spatial distribution of dead and vital bacteria in the early formation of native dental biofilm. An experimental dental biofilm model in the oral cavity was established by enamel slabs and the spatial distribution of dead and vital bacteria in the early colonization of native dental biofilm on the enamel surface was observed by in situ real-time and dynamic observations and optical sections utilizing confocal laser scanning microscope (CLSM) and live and dead bacterial fluorescence staining technique. At the initial stage of dental biofilm formation, the structure was sparse and the percentage of dead cells reached 70% - 80% at the inner layers. In the middle layers the structure became denser than in the inner layers, which was mainly composed of vital cells (40% - 70%), and void-like structures were surrounded by vital bacteria. In the outer layers, the structure was sparse and vital cells occupied 20% - 40%. Native dental biofilms showed an uneven spatial distribution of vital and dead microorganisms. The percentage of vital microorganisms was lower adjacent to the enamel surface, increased in the z-axis towards the central parts, and decreased again towards the outer layers. The dead bacteria is an integral component in the early formation of native dental biofilm. Bacteria in the biofilms increased with time forming abundant channels.

  11. 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.

  12. Improvement in the Spatial Distribution of Pain, Somatic Symptoms, and Depression After a Weight Loss Intervention.

    Science.gov (United States)

    Schrepf, Andrew; Harte, Steven E; Miller, Nicole; Fowler, Christine; Nay, Catherine; Williams, David A; Clauw, Daniel J; Rothberg, Amy

    2017-12-01

    Weight loss is known to improve pain localized to weight-bearing joints but it is not known how weight loss affects the spatial distribution of pain and associated somatic symptoms like fatigue. We sought to determine if weight loss using a low-calorie diet improves pain, affect, and somatic symptoms commonly associated with chronic pain conditions in an observational study. We also documented changes in inflammatory markers in serum before and after weight loss. Participants were 123 obese individuals undergoing a 12- to 16-week calorie restriction weight loss intervention. The spatial distribution of pain, symptom severity (eg, fatigue, sleep difficulties), depression, and total fibromyalgia scale scores were measured before and after weight loss. Pain (P = . 022), symptom severity (P = .004), depression (P loss; men showed greater improvement than women on somatic symptoms and fibromyalgia scores (both P loss may improve diffuse pain and comorbid symptoms commonly seen in chronic pain participants. This article presents the effect of a weight loss intervention on characteristics of chronic pain, including the spatial distribution of pain and comorbid somatic symptoms. Weight loss appeared to produce larger improvements in somatic symptoms for men. Copyright © 2017 The American Pain Society. Published by Elsevier Inc. All rights reserved.

  13. Experimental muscle pain changes the spatial distribution of upper trapezius muscle activity during sustained contraction.

    Science.gov (United States)

    Madeleine, Pascal; Leclerc, Fredéric; Arendt-Nielsen, Lars; Ravier, Philippe; Farina, Dario

    2006-11-01

    To investigate the effect of local excitation of nociceptive muscle afferents on the spatial distribution of muscle activity. Surface electromyographic (EMG) signals were recorded from the upper trapezius muscle of 10 healthy volunteers with a 5 x 13 electrode grid during 90-s isometric contractions before, during, 15 and 30 min after intramuscular injection of hypertonic (painful) or isotonic (non-painful) saline. From the multi-channel EMG recordings, two-dimensional maps of root mean square and mean power frequency were obtained. The centre of gravity of the root mean square map was used to quantify global changes in the spatial distribution of muscle activity. During sustained contractions, average root mean square increased, average mean frequency decreased and the centre of gravity moved cranially. During experimental muscle pain, compared to before injection, the average root mean square decreased and there was a caudal shift of the centre of gravity. Fifteen minutes after the painful injection the centre of gravity returned to its original position. Short-term dynamic reorganization of the spatial distribution of muscle activity occurred in response to nociceptive afferent input. The study furnishes an extension of the pain adaptation model indicating heterogeneous inhibition of muscle activity.

  14. The Association between Foveal Morphology and Macular Pigment Spatial Distribution: An Ethnicity Study.

    Directory of Open Access Journals (Sweden)

    Irene Ctori

    Full Text Available Macular pigment (MP spatial distribution varies considerably among individuals. We investigated ethnic variations in MP spatial distribution in relation to foveal architecture.We measured MP optical density (MPOD using heterochromatic flicker photometry (MAP test, City, University of London in 76 white, 80 South Asian and 70 black volunteers (18 to 39 years. MPOD spatial profiles were classified objectively as exponential, ring-like or central dip, based on deviations away from an exponential fit. Measurements including total retinal thickness (RT, inner retinal layer (IRL, inner and outer plexiform layer (IPL and OPL thickness, foveal width and foveal pit slope were taken from Spectralis SD-OCT (Heidelberg, Germany scans.Integrated MPOD up to 1.8° (MPODint was higher in South Asian (0.84±0.26 and black (0.84±0.31 than whites (0.63±0.24, P0.05.We report a significant difference in the amount and distribution of MP between ethnicities that is not explained by variations in foveal morphology.

  15. The Spatial Distribution of Volcanic Events on Io in 2013-2015

    Science.gov (United States)

    de Kleer, Katherine R.; de Pater, Imke

    2015-11-01

    The spatial distribution of heat flow on Io is a key prediction of tidal heat dissipation models, and therefore provides an important constraint for understanding Io’s interior. However, the majority of our knowledge about eruption locations is derived from geological features tracing long time periods (e.g. Hamilton et al., 2013), and from activity during the Galileo era (e.g. Davies et al., 2015; Veeder et al., 2015).We report on new results from a campaign to image Io in the near-infrared with adaptive optics on the Keck and Gemini N telescopes. We observed Io on 93 nights between August 2013 and June 2015, detecting volcanic activity at dozens of hot spot locations. We present the spatial distribution of the observed eruption sites during this period, and compare this with the distributions inferred from past hot spot and patera locations by previous authors. We discuss the locations of eruptions of different magnitudes, including a preponderance of bright activity at latitudes polewards of 45 degrees in both hemispheres and an apparent spatial clustering of activity in the months following large eruptions. Finally, we address the durations of the detected eruptions, as well as connecting our findings to the EXCEED Mission’s observations of the Io plasma torus during the same time period.

  16. 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.

  17. 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 vehicles and for all pollutants. However, we identified high cluster only for the light vehicles.

  18. The Spatial Heterogeneity between Japanese Encephalitis Incidence Distribution and Environmental Variables in Nepal

    Science.gov (United States)

    Impoinvil, Daniel E.; Solomon, Tom; Schluter, W. William; Rayamajhi, Ajit; Bichha, Ram Padarath; Shakya, Geeta; Caminade, Cyril; Baylis, Matthew

    2011-01-01

    Background 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. Methods 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. Results 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. Conclusion 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

  19. 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

  20. Off-Grid Direction of Arrival Estimation Based on Joint Spatial Sparsity for Distributed Sparse Linear Arrays

    Directory of Open Access Journals (Sweden)

    Yujie Liang

    2014-11-01

    Full Text Available In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA estimation with distributed sparse linear arrays (SLAs and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach.