Spatial Distribution Of Parameters Research Articles

Different-scale distribution of collembola in homogenous ground vegetation: Stability of parameters in space and time

We have tested the hypothesis about the existence of species-specific patterns of local spatial distribution of Collembola, i.e., combinations of differently sized aggregations or the absence of distinct aggregations. The presence of such patterns was previously demonstrated for some abundant collembolan species in the sphagnum pine forests of Karelia using the special fractal design of surveys, with groups of core samples taken at different distances. The aim of the present work was to find out whether the patterns observed in sphagnum pine forests were preserved in the mesophytic and xerophytic variants, namely green moss and lichen pine forests. As a rule, the parameters of local spatial distribution of species were quite similar in different seasons, in drier habitats as well as in humid ones. Some characteristics of collembolan aggregations at different levels, such as their size, density, and strength relative to the background, were described, and the occurrence of individual species in differently sized plots was estimated. On the whole, the typical traits of local spatial distribution of collembolan species were preserved not only within each biotope but also in different habitats. However, these species-specific patterns were not absolutely constant, as some species became more clumped under xerophytic conditions. The types of spatial redistribution of springtails accompanying an increase in their population density are discussed.

A new method of detecting changes in corneal health in response to toxic insults

The size and arrangement of stromal collagen fibrils (CFs) influence the optical properties of the cornea and hence its function. The spatial arrangement of the collagen is still questionable in relation to the diameter of collagen fibril. In the present study, we introduce a new parameter, edge-fibrillar distance (EFD) to measure how two collagen fibrils are spaced with respect to their closest edges and their spatial distribution through normalized standard deviation of EFD (NSDEFD) accessed through the application of two commercially available multipurpose solutions (MPS): ReNu and Hippia. The corneal buttons were soaked separately in ReNu and Hippia MPS for five hours, fixed overnight in 2.5% glutaraldehyde containing cuprolinic blue and processed for transmission electron microscopy. The electron micrographs were processed using ImageJ user-coded plugin. Statistical analysis was performed to compare the image processed equivalent diameter (ED), inter-fibrillar distance (IFD), and EFD of the CFs of treated versus normal corneas. The ReNu-soaked cornea resulted in partly degenerated epithelium with loose hemidesmosomes and Bowman's collagen. In contrast, the epithelium of the cornea soaked in Hippia was degenerated or lost but showed closely packed Bowman's collagen. Soaking the corneas in both MPS caused a statistically significant decrease in the anterior collagen fibril, ED and a significant change in IFD, and EFD than those of the untreated corneas (p<0.05, for all comparisons). The introduction of EFD measurement in the study directly provided a sense of gap between periphery of the collagen bundles, their spatial distribution; and in combination with ED, they showed how the corneal collagen bundles are spaced in relation to their diameters. The spatial distribution parameter NSDEFD indicated that ReNu treated cornea fibrils were uniformly distributed spatially, followed by normal and Hippia. The EFD measurement with relatively lower standard deviation and NSDEFD, a characteristic of uniform CFs distribution, can be an additional parameter used in evaluating collagen organization and accessing the effects of various treatments on corneal health and transparency.

Seasonal activity and spatial distribution pattern of Eotetranychus frosti (Acari: Tetranychidae) in an unsprayed apple orchard of Kermanshah, Western Iran

Population density and spatial distribution pattern of Eotetranychus frosti (McGregor) was determined in an unsprayed apple orchard of Kermanshah, Western Iran, from 31 st May till 7 th November 2007. On each sample date 130 leaves were selected, with a relative variation of 4.31%. Different methods of indices of dispersion, regression models (Taylor and Iwao), Morisita’s index and Lloyd’s mean crowding to mean was used to determine the spatial distribution pattern of this mite. The mean population density of this mite per leaf was 2.079. The highest population density of E. frosti was in 9 th August (4.938 per leaf). Index of dispersion ( S 2 /m = 6.516), aggregation index ( 1/k= 2.653) and Lloyd’s mean crowding to mean ( m * /m= 3.653) showed an aggregated distribution for this species. The Taylor's power law and Iwao's patchiness regression methods showed aggregated spatial distribution too. Some changes in spatial distribution pattern from aggregated to random were observed using Morisita’s index in different sampling dates. Three different coefficients of Taylor, Iwao and K were used to optimize the sample size for future studies. The lowest optimized sample size (34.70) was obtained by using the Taylor's coefficients. Spatial distribution parameters of E. frosti can be used to improve a sampling program of this mite in a framework of an integrated pest management system.

GEOINFORMATION DATABASE FOR EVALUATION OF POTENTIAL NITRATE POLLUTION OF SURFACE WATER AND GROUNDWATER

Presented by the rationale for the structure, methods and results of creation of the geoinformation database for assessing the potential nitrate-made pollution of surface and groundwater in Odessa region. The database includes basic derivatives and digital layers of spatial information characterizing relief, hydrographic network, soil cover, land-use and spatial distribution parameters of the mathematical model of evaluation, which is selected as a regression model, developed at the Aristotle University of Thessaloniki (Greece). The database is used raster and vector spatial data models, but the basic model is a raster with the size of the raster 3710 x 3632 and with the raster cell size 92.6 m.

Mineralogy evaluation and segmentation using dual‐energy microtomography

Computed tomography is a nondestructive technique that allows the visualization of internal structures of a sample. However, the attenuation coefficient of a material to radiation, shown in grayscale levels, can be interpreted as the combination of parameters of density and atomic number. Thus, the separation of different structures of equal attenuation is no simple task, requiring prior knowledge of the sample composition, which is usually not available. By calibration of a high‐resolution microtomographic system through the dual‐energy technique, using materials of known composition, it is possible to identify and segment images to obtain the spatial distribution of parameters of density and atomic number. As the combination of these two data is unique to each material, it allows the identification and separation of regions, indistinguishable in common grayscale images obtained by microtomography. In this work, we developed a methodology for the evaluation of the dual‐energy technique, as well as assessment, segmentation, and reconstruction of images on a scale of density and atomic number; added to this, we sought to develop a code in MatLab® for data, image processing, and mineralogical segmentation. The results show the capabilities of the dual‐energy technique, combined with the microtomography technique, to obtain information on the composition of the sample, its three‐dimensional spatial distribution, and separation of structures of the same composition. Copyright © 2015 John Wiley &amp; Sons, Ltd.

SPATIAL DISTRIBUTION OF ANNUAL RAINFALL IN BOSNIA AND HERZEGOVINA USING SPATIAL KRIGING INTERPOLATOR

Precipitation and air temperature are the basic meteorological elements in the climate research, indicating and influencing the general characteristics of the atmospheric circulation by their spatiotemporal dynamics, determinating the general climate character of the location. In this paper, the interpretation of the pluviometric regime in Bosnia and Herzegovina will be based on quantitative parameters of the horizontal spatial distribution of the mean annual precipitation sums resulting by applying GIS based kriging spatial interpolator. The results of research have shown the annual pluviometric GRID for Bosnia and Herzegovina of high spatial resolution enabling, beside the horizontal spatial distribution, the production of the detailed transverse and longitudinal pluviometric profiles.

Fast ignition when heating the central part of an inertial confinement fusion target by an ion beam

We investigate the ignition and burning of a precompressed laser fusion target when it is rapidly heated by an ion beam with the formation of a temperature peak in the central part of the target. We present the results of our comprehensive numerical simulations of the problem that include the following components: (1) the target compression under the action of a profiled laser pulse, (2) the heating of the compressed target with spatially nonuniform density and temperature distributions by a beam of high-energy ions, and (3) the burning of the target with the initial spatial density distribution formed at the instant of maximum target compression and the initial spatial temperature distribution formed as a result of the compressed-target heating by an ion beam. The dependences of the threshold energies of the igniting ion beam and the thermonuclear gain on the width of the Gaussian beam ion energy spectrum have been established. The peculiarities of fast ignition by an ion beam related to the spatial distribution of parameters for the target precompressed by a laser pulse are discussed.

Simple analytic relations for estimating parameters of the positive column of an electronegative glow discharge in a halogen-containing gas mixture

Asymptotic analysis of the continuity equations for the positive charge plasma of a low- and moderate-pressure dc electronegative discharge is performed under the simple assumption of independence of the rates of plasma-chemical processes from coordinates. As a novelty, the ion diffusion is taken into account for the case when the ion-ion recombination dominates among the perishing mechanism of negative ions. The resultant simple analytic expressions make it possible to estimate (with an error not exceeding 15–25%) the geometrical parameters of spatial distributions of charged particle concentrations in this plasma, as well as the energy parameters, without resorting to complicated numerical simulation.

Flow in double-porosity aquifers: Parameter estimation using an adaptive multiscale method

The double porosity model (DPM) concept is a widely used approach to simulate flow in fractured aquifers. Parameter estimation methods to calibrate standard groundwater flow models have been rarely applied to the DPM. In this paper, we make use of a multiscale parameterization which defines the spatial distribution of parameter by an adaptive discretization refined within the iterative inversion procedure. The mathematical developments, including a presentation of the adjoint state equations, and the adaptive multiscale algorithm are described in detail. The parameter estimation procedure is applied to a heterogeneous synthetic case, where each type of parameter is spatially distributed according to a different variogram. Without any prior knowledge of theses variograms conditioning the adaptive multiscale method, the latter is able to retrieve with good precision the reference model for both its local parameter values and their associated spatial distribution.

The dilemma of spatial representation for urban hydrology semi-distributed modelling: Trade-offs among complexity, calibration and geographical data

Summary Semi-distributed models are widely used in urban hydrology, supported by the abundance and detail of geographical data. The inclusion of these data into hydrological models requires however an increasing complexity of the model structure with spatially distributed parameters, potentially driving to over-parameterisation issues. In this paper, different configurations and model structures, including an increasing quantity of geographical information, are tested for both water quantity and water quality on the widely used SWMM5 model for a 2.3 km2 catchment. The Nash criterion is used to calibrate the model and compare alternative configurations. Results for water quantity modelling show that the inclusion of some basic geographical information, particularly on land uses, clearly improves performances, but further refinements are less effective. Uncalibrated models with sufficient land use information reach performances comparable with those of calibrated models. For water quality modelling (suspended solids concentration), the best modelling performance is obtained by a compromise solution with moderate spatial distribution of parameters: no spatial distribution drives to limited performances, while an excessive one to severe over-parameterisation. A comparison to suspended solids measurements realized on a single road of the catchment shows that parameters providing good performances at the catchment scale are a realistic, although non optimal, representation of local scale processes.

GIS-based hydrogeochemical analysis tools (QUIMET)

A software platform (QUIMET) was developed to improve the sorting, analysis, calculations, visualizations, and interpretations of hydrogeochemical data in a GIS environment. QUIMET is composed of a geospatial database plus a set of tools specially designed for graphical and statistical analysis of hydrogeochemical data. The geospatial database has been designed to include organic and inorganic chemical records, as well as relevant physical parameters (temperature, Eh, electrical conductivity). The instruments for analysis cover a wide range of methodologies for querying, interpreting, and comparing groundwater quality data. They include, among others, chemical time-series analysis, ionic balance calculations, correlation of chemical parameters, and calculation of various common hydrogeochemical diagrams (Salinity, Schöeller–Berkaloff, Piper, and Stiff). The GIS platform allows the generation of maps of the spatial distribution of parameters and diagrams. Moreover, it allows performing a complete statistical analysis of the data including descriptive statistic univariate and bivariate analysis, the latter including generation of correlation matrices and graphics. Finally, QUIMET offers interoperability with other external platforms. The platform is illustrated with a geochemical data set from the city of Badalona, located on the Mediterranean coast in NE Spain.

Formulas for estimating the parameters of the positive column of a glow discharge in electronegative gases for finite ionic temperatures

Explicit simple but at the same time sufficiently exact explicit analytic expressions are obtained under the simplest assumption concerning the constancy of plasma-chemical processes in the plasma of the positive column of low- and moderate-pressure discharges in the case of detachment by neutral particles. These relations make it possible to rapidly estimate the geometrical parameters of spatial distributions of charged particle concentrations in this plasma, as well as its energy parameters, without resorting to numerical simulation. For the first time, the finiteness of ionic temperatures and the presence of ion diffusion are taken into account. It is shown that transverse stratification of the electronegative plasma into regions with different ionic compositions is a consequence of nonisothermality of the plasma.

Simple analytic formulas for estimating the parameters of the positive column of a glow discharge in electronegative gases

Simple analytic expressions are analyzed for the plasma of the positive column of low- and moderate-pressure discharges in the case of detachment by neutral particles. These relations make it possible to easily and rapidly estimate the parameters of spatial distributions of charged particle concentrations in this plasma, as well as its energy parameters. For the first time, the conditions for applicability of these relations are determined and their accuracy is estimated.

Spatial Arrangement of the Microvascular Bed in the Human Placenta

Spatial Arrangement of the Microvascular Bed in the Human Placenta The knowledge of the spatial arrangement of microvascular bed is necessary for understanding the organ function. Various models and functional interpretations of the spatial organization of placental microvascular bed were created in the past decades however their plausibility was highly influenced by technical level of used methods. In this paper, methods and results of those studies are summarized and discussed. As the placenta in utero is hardly accessible for examination, the data regarding spatial arrangement of microvascular bed were obtained from ex vivo studies after termination of pregnancy. Imaging methods, i.e. X-ray angiography, X-ray microcomputed tomography and nowadays also MRI yielded information mainly on the spatial distribution and quantitative parameters of placental arterial system. The combination of SEM and corrosion casts demonstrated that capillaries of terminal villi branch from arterioles of mature intermediate villi, some capillary segments interconnect the capillary bed of neighboring terminal villi, and venules are arranged parallel with arterioles of mature terminal villi.

A statistical approach to root system classification.

Plant root systems have a key role in ecology and agronomy. In spite of fast increase in root studies, still there is no classification that allows distinguishing among distinctive characteristics within the diversity of rooting strategies. Our hypothesis is that a multivariate approach for “plant functional type” identification in ecology can be applied to the classification of root systems. The classification method presented is based on a data-defined statistical procedure without a priori decision on the classifiers. The study demonstrates that principal component based rooting types provide efficient and meaningful multi-trait classifiers. The classification method is exemplified with simulated root architectures and morphological field data. Simulated root architectures showed that morphological attributes with spatial distribution parameters capture most distinctive features within root system diversity. While developmental type (tap vs. shoot-borne systems) is a strong, but coarse classifier, topological traits provide the most detailed differentiation among distinctive groups. Adequacy of commonly available morphologic traits for classification is supported by field data. Rooting types emerging from measured data, mainly distinguished by diameter/weight and density dominated types. Similarity of root systems within distinctive groups was the joint result of phylogenetic relation and environmental as well as human selection pressure. We concluded that the data-define classification is appropriate for integration of knowledge obtained with different root measurement methods and at various scales. Currently root morphology is the most promising basis for classification due to widely used common measurement protocols. To capture details of root diversity efforts in architectural measurement techniques are essential.

Metal exposure and accumulation patterns in free-range cows (Bos taurus) in a contaminated natural area: Influence of spatial and social behavior

Possible effects of spatial metal distribution, seasonal-, ecological- and ethological parameters, on the metal exposure of cows were investigated. Therefore the habitat use, vegetation selection and foraging behavior of two free ranging Galloway herds in a metal polluted nature reserve were observed. Metal concentrations in soil, vegetation, hair, blood and feces were measured. Although both herds lived in the same reserve, their metal exposure differed significantly. A high consumption of soft rush by herd 1 during winter for instance was responsible for a large increase in daily Cd intake. The results of this study suggest that the exposure and health risks of large grazers can probably not only be predicted by a general monitoring of soil and vegetation pollution. Also detailed information about the occurring vegetation types, spatial habitat use together with the social- and foraging behavior and diet selection of the species need to be studied.

Void Formation and Spatial Distribution in Plasma Sprayed Nd-Fe-B Coatings

Formation of voids is inevitable in plasma sprayed coatings and the role of voids on coating properties has long been established. In fact, the void content within coatings is adjusted by optimizing the process parameters to obtain coatings with desirable performance. Quantification of voids via image analysis allows determination of not only the void content within a coating, but also the spatial distribution of the voids. Void content in plasma sprayed neodymium iron boron (Nd-Fe-B) coatings was adjusted by changing the standoff distance, and was found to vary from 1.8 to 8.2%. Spatial distribution parameters, which include nearest neighbor distance (d min), mean near neighbor distance (d mean), and nearest neighbor angle (θn), were determined via the Dirichlet tessellation method. Coefficient of variation (COV) values of d min and d mean allow determination of inhomogeneity and degree of clustering of the voids within a coating. The θn values reveal the anisotropic behavior of voids within plasma sprayed coatings. The influence of void content and its spatial distribution within the coatings on the microhardness and elastic modulus of coatings was determined.

A methodology based on spatial distribution of parameters for understanding affect of rainfall and vegetation density on groundwater recharge

Accurate estimation of groundwater recharge is extremely important for propermanagement of groundwater systems. Attempts have been made by various researchers torelate impact of various parameters on groundwater recharge. In the present study, amethodology based on spatial distribution of parameters has been developed forunderstanding affect of rainfall and vegetation density on groundwater recharge.Normalized Difference Vegetation Index (NDVI) has been used as an indicative parameterfor vegetation density. Raster layers of recharge and various parameters were created for thestudy area and simultaneous values for these parameters were retrieved at the cell level.Zonal analysis was then carried out to understand affect of these parameters ongroundwater recharge. It is observed that the value of recharge increases up to a certainvalue of NDVI, beyond which it starts decreasing with further increase in value of NDVI.The study also reveals a linear trend between groundwater recharge and rainfall. The resultof this study does not provide method of calculating recharge by using single parametersuch as rainfall or NDVI, however, it explores affect of variation in these parameters ongroundwater recharges. The study provides a new insight into the complex interrelationshipbetween groundwater recharge and vegetation density.

Generalization of transmission line models for deriving the impedance of diffusion and porous media

System simulation and system identification are common problems in science and technology. In the field of electrochemistry this is of interest for systems, such as porous electrodes and mechanisms, such as diffusion. These are relevant for technical applications, such as energy storage and corrosion protection. Models describing the electrical behavior of such systems are based not only on schematics, physical and chemical approaches but also on equivalent circuits. Sometimes simplifications are applied to the conduction path and the spatial distribution of parameters. Due to the availability of many different models, the selection of a suitable model for a specific application is very difficult. Hence, identifying model similarities allows for a better understanding of each mechanism, reducing the number of mathematical calculations, simplifying model evaluation and thereby reducing the complexity. In this paper, a more general point of view of impedance in terms of a generalized transmission line model is considered. The differential equation of the transmission line model and its general solution is discussed. Furthermore, different boundary conditions are applied to obtain the solution for different electrochemical systems. The results for diffusion and porous electrodes are discussed in more detail, the solution of the differential equations are compared with the established models and the impedance behavior is analyzed. An effort has thus been made to analyze and remove ambiguity from impedance model equations. Removing ambiguity simplifies the analysis of model parameters influencing impedance behavior and additionally improves the robustness of nonlinear parameter optimization techniques.

Assessing precipitation distribution impacts on droughts on the island of Crete

Abstract. Precipitation records from 56 stations on the island of Crete (Greece) revealed that areal mean annual precipitation is of a strong orographic type and its magnitude decreases in west-east direction by as much as 400 mm on average. Amongst many parameters that influence precipitation, the elevation and longitude were the most important and provided the highest spatial correlation. It was found that during the year with minimum precipitation, the precipitation shortage was greater at high elevations while the precipitation excess during the year with maximum precipitation was greater in the western part of the island. The assessment of the spatial and temporal distribution of droughts was carried out with the aid of the Spatially Normalized Standardized Precipitation Index (SN-SPI) for the period 1974–2005 in order to compare drought conditions between neighbouring areas of differing precipitation heights. The analysis showed that severe droughts occurred around the year 1992–1993, with a duration of up to 3 yr. Multiple linear regression (MLR) modeling of precipitation in conjunction with cluster analysis of drought duration exhibits the linkage between precipitation, droughts and geographical factors. This connection between spatial precipitation distribution and geographical parameters provides an important clue for the respective spatial drought pattern. The above findings on the spatio-temporal drought distribution will update the current~drought management plans by developing more precise drought warning systems.