Spatial Density Distribution Research Articles

Dairy Cattle Density and Temporal Patterns of Human Campylobacteriosis and Cryptosporidiosis in New Zealand

Public health risks associated with the intensification of dairy farming are an emerging concern. Dairy cattle are a reservoir for a number of pathogens that can cause human illness. This study examined the spatial distribution of dairy cattle density and explored temporal patterns of human campylobacteriosis and cryptosporidiosis notifications in New Zealand from 1997 to 2015. Maps of dairy cattle density were produced, and temporal patterns of disease rates were assessed for urban versus rural areas and for areas with different dairy cattle densities using descriptive temporal analyses. Campylobacteriosis and cryptosporidiosis rates displayed strong seasonal patterns, with highest rates in spring in rural areas and, for campylobacteriosis, summer in urban areas. Increases in rural cases often preceded increases in urban cases. Furthermore, disease rates in areas with higher dairy cattle densities tended to peak before areas with low densities or no dairy cattle. Infected dairy calves may be a direct or indirect source of campylobacteriosis or cryptosporidiosis infection in humans through environmental or occupational exposure routes, including contact with animals or feces, recreational contact with contaminated waterways, and consumption of untreated drinking water. These results have public health implications for populations living, working, or recreating in proximity to dairy farms.

Specificities of the Nonlocal EDF Formation in a Dusty Plasma With the Different Spatial Distribution of the Microparticle Density

The formation of a nonlocal electron distribution function (EDF) in an argon dusty plasma of a dc glow discharge has been studied in a wide range of microparticle densities and their different spatial distributions inside a dusty cloud have also been explored. It is shown that the spatial profile of charges and the ambipolar potential can vary greatly, both with a change in the absolute values of the density of dust particles and the type of their spatial distribution. In turn, changes in the profiles of the ambipolar potential lead to strong differences in the nonlocal EDF at different points of the tube radius. This is most clearly seen at high densities of dust particles when nonmonotonic profiles of the potential distribution and reversal of the sign of the ambipolar field are formed. In this extreme case, great changes in the nonlocal EDF are observed not only at the discharge periphery but also inside the dust cloud.

Can Radioactive Emanations in a Seismically Active Region Affect Atmospheric Electricity and the Ionosphere?

—Anomalous variations in radon emissions from the soil are sometimes observed before and after strong earthquakes. In this paper, we theoretically analyze the known hypothesis that these variations in radioactive emanations in the surface layer of the atmosphere cause variations in the vertical background current in the atmosphere with subsequent changes in the electron density {{n}_{e}} in the lower ionosphere. For this purpose, we will first assess the relation between radon emission variations and the vertical atmospheric current flowing into the ionosphere. Then we will solve a model problem concerning the spatial distribution of plasma density and electric field perturbations occurring in the E-layer of the ionosphere caused by an inflowing vertical current. It was believed that the current flowing into this layer contains only an electron component and is attenuated only by the recombination of electrons. The estimate of the maximum variation {{n}_{e}} is at least 3–5 orders of magnitude smaller than the observed anomalous variations, which allows us to conclude that this hypothesis is not plausible.

EVALUATION OF PIXEL SELECTION METHODS FOR TRAFFIC INFRASTRUCTURE MONITORING USING SENTINEL-1 INSAR

Abstract. The Synthetic Aperture Radar (SAR) satellite Sentinel-1 provides excellent traffic infrastructure monitoring capabilities due to its short revisit time, wide-scale coverage and free of charge data policy. However, pixels from Sentinel-1 have a medium spatial resolution so that traffic infrastructure is only covered by a few pixels. Moreover, Interferometric Synthetic Aperture Radar (InSAR) yields deformation time series for coherent pixels only, thus limiting the number of pixels reporting the ground motion at traffic infrastructure. Although various InSAR time series methods have been successfully applied for traffic infrastructure monitoring, the selection of appropriate methods achieving a high pixel density has not yet been evaluated. In this study, we test whether we can improve the monitoring capabilities by combining different InSAR time series methods. On the one hand, we applied widely used Stanford Method for Persistent Scatterers (StaMPS) as a baseline method to retrieve the deformation time series. On the other hand, we enhanced the phase quality in a pre-processing step using the Phase-Linking (PL) approach and afterwards estimated the deformation time series also with StaMPS based on pixels selected by PL. We compared and evaluated the achieved pixel densities from both methods at main roads, highways and railways in a study area in Germany. We found that the InSAR time series methods selected complementary sets of pixels at all traffic infrastructure types. Moreover, the results indicate a great potential for railway monitoring using Sentinel-1 InSAR due to both high pixel density and homogeneous spatial distribution of pixels. Interestingly, coherent scatterers selected by StaMPS were observed to coincide with large traffic signs at highways which show a double-bounce scattering in the amplitude images. This study shows the benefits of combining PL and StaMPS for increased pixel density at traffic infrastructure and confirms Sentinel-1 data as a suitable data source for traffic infrastructure monitoring.

Towards an optimal estimation of cosmological parameters with the wavelet scattering transform

Optimal extraction of the non-Gaussian information encoded in the Large-Scale Structure (LSS) of the universe lies at the forefront of modern precision cosmology. We propose achieving this task through the use of the Wavelet Scattering Transform (WST), which subjects an input field to a layer of non-linear transformations that are sensitive to non-Gaussianity in spatial density distributions through a generated set of WST coefficients. In order to assess its applicability in the context of LSS surveys, we apply the WST on the 3D overdensity field obtained by the Quijote simulations, out of which we extract the Fisher information in 6 cosmological parameters. It is subsequently found to deliver a large improvement in the marginalized errors on all parameters, ranging between $1.2-4\times$ tighter than the corresponding ones obtained from the regular 3D cold dark matter + baryon power spectrum, as well as a $50 \%$ improvement over the neutrino mass constraint given by the marked power spectrum. Through this first application on 3D cosmological fields, we demonstrate the great promise held by this novel statistic and set the stage for its future application to actual galaxy observations.

Recent progress on the J-TEXT three-wave polarimeter-interferometer

The J-TEXT three-wave polarimeter-interferometer system (POLARIS), which measures time-space distribution of electron density and current density, has been optimized with both the optical system and the equilibrium reconstruction method. The phase resolution of a Faraday rotation angle has been improved from 0.1 to 0.06 degree in chords from –0.18 to 0.18 m (plasma minor radius), and the sawtooth oscillation behavior has been detected by Faraday rotation angle measurement. By combining the POLARIS measured data and the equilibrium and fitting code (EFIT), an upgraded equilibrium reconstruction method has been developed, which provides a more accurate temporal and spatial distribution of current density and electron density. By means of the optimized POLARIS and improved equilibrium reconstruction, variations of profiles with increasing density have been carried out, under both Ohmic and electron cyclotron resonance heating discharges.

Spin-dependent transport in a driven non-collinear antiferromagnetic fractal network

Non-collinear magnetic texture breaks the spin-sublattice symmetry which gives rise to a spin-splitting effect. Inspired by this, we study the spin-dependent transport properties in a non-collinear antiferromagnetic fractal structure, namely, the Sierpinski Gasket (SPG) triangle. We find that though the spin-up and spin-down currents are different, the degree of spin polarization is too weak. Finally, we come up with a proposal, where the degree of spin polarization can be enhanced significantly in the presence of a time-periodic driving field. Such a prescription of getting spin-filtering effect from an unpolarized source in a fractal network is completely new to the best of our knowledge. Starting from a higher generation of SPG to smaller ones, the precise dependencies of driving field parameters, spin-dependent scattering strength, interface sensitivity on spin polarization are critically investigated. The spatial distribution of spin-resolved bond current density is also explored. Interestingly, our proposed setup exhibits finite spin polarization for different spin-quantization axes. Arbitrarily polarized light is considered and its effect is incorporated through Floquet–Bloch ansatz. All the spin-resolved transport quantities are computed using Green’s function formalism following the Landauer–Büttiker prescription. In light of the experimental feasibility of such fractal structures and manipulation of magnetic textures, the present work brings forth new insights into spintronic properties of non-collinear antiferromagnetic SPG. This should also entice the AFM spintronic community to explore other fractal structures with the possibility of unconventional features.

Investigation on the radial distribution of electron density in a miniaturized ECR ion thruster of wide-range operations

A miniaturized thruster with a wide tuning range of thrust plays an important role for the drag-free control in the task of space-borne gravitational wave detection. For the design of a high-precision miniaturized thruster, it is necessary to study the spatial distribution of the electron density in its discharge chamber. This work investigates the electron density distribution in an ECR ion thruster of 2-cm diameter, with the input microwave power and mass flow rate tuned in a wide range. At relatively low power and flow rate, there is a peak of electron density at the radial position r = 4 mm, which is around the region of resonant power absorption. However, the density distribution in the center region becomes flat with the increase of power and flow rate; at high power and flow rate, it tends to be a Bessel function with a peak in the center (r = 0 mm). In the view of tuning of thrust, it is found that the above variation of electron density distribution can be as important as (or even more important than) the variation of peak value of electron density. A further discussion on the influence of the evolution of electron density distribution is given by considering the thruster design, operation, and control for the task of space-borne gravitational wave detection.

Rarefied gas mixtures with large species mass ratio: Outflow into vacuum

The theoretical study of the processes of the outflow of a binary gas mixture from a source into a vacuum through an orifice in an infinitely thin wall is presented. Two mixtures with a large species mass ratio K are considered: Au–Ne (K = 9.76) and Au–He (K = 49.21). The work continues the study of the flow of Ag–He mixture (K = 26.95) started in Bykov and Zakharov [“Binary gas mixture outflow into vacuum through an orifice,” Phys. Fluids 32, 067109 (2020)]. The results of the direct simulation Monte Carlo made it possible to propose approximations of the mass flow rates of the species and the mixture depending on the species mass ratio, the flow rarefaction degree, and the mole fraction of light species in the source. It is shown that with an increase in the parameter K, an increase in the dimensionless mass flow rate of the mixture referred to the corresponding free molecular value is observed. The maximum dimensionless flow rate corresponds to the near-continuum regime and exceeds the value obtained using the hydrodynamic approximation and the equivalent single gas approach. A variation of K also leads to changes in the spatial distributions of the dimensionless density and velocity of the mixture and some axial focusing of the flow. An increase in the species mass ratio for the case of a small initial mole fraction of the heavy species in the source for a flow regime close to the hydrodynamic one leads to an increase in acceleration and axial focusing of the heavy species.

Propagation characteristics of relativistic ultrashort laser pulse in inhomogeneous plasma

We study the propagation of a relativistic ultrashort laser pulse in two-dimensional inhomogeneous plasma with a density ripple based on the theoretical analysis and the particle-in-cell simulation. An analytical solution of the laser pulse propagating in the homogeneous plasma is completely obtained. It is found that the stable propagation of the relativistic ultrashort laser pulse in homogeneous plasma can be realized, and the propagation distance and intensity of the laser pulse and the spatial distribution of electron density can be effectively modulated by adjusting the pulsewidth of the incident laser and the plasma frequency. More interestingly, in the inhomogeneous plasma with a density ripple, when the wave amplitude of the density ripple is less than a critical value, the intensity of the ultrashort laser pulse is almost unchanged and the propagation characteristics of the laser in the inhomogeneous plasma are basically consistent with those in the homogeneous plasma. However, when the wave amplitude of the density ripple is larger than the critical value, the inhomogeneity of the plasma has an obvious effect on the laser characteristics, and the intensity and the spatial distribution of the laser pulse will be modulated by the plasma density ripple. The influence of the laser pulsewidth, plasma density, and plasma density ripple on the laser characteristics is discussed in detail.

On density distribution of Ti atom and ion ground states near the target in HiPIMS discharge using cavity ring-down spectroscopy and laser induced fluorescence

Cavity ring-down spectroscopy combined with laser induced fluorescence was applied during a high-power impulse magnetron sputtering of Ti target to determine the time evolutions and spatial distributions of Ti atom and ion densities of levels belonging to the ground state multiplets (GSM) near the sputtered target. From these densities, an estimate of the time evolution and spatial distribution of the ionization degree near the target was calculated. It was found that the densities (number of particles per unit volume) of levels in GSM of Ti atom and ion increases with their level energies and the highest levels in GSMs show an inversion in their populations (the density of level divided by its statistical weight) during a voltage pulse. The population inversion (a higher population of levels with a higher energy than those with lower ones) is distinct for the highest level in GSM of Ti+ ion and it persists even at 40 μs after the voltage pulse end. The sum of ground state level densities reaches values up to 8.3 × 1011 cm−3 for Ti+ ions above the target racetrack and up to 4.8 × 1011 cm−3 for Ti atoms above the target center for the regime with the peak power density of 498 W cm−2. A frequent ionization of Ti atoms above the target racetrack is manifested by distinct drops in the Ti atom spatial distribution. This leads to a very high ionization degree up to 94% at the racetrack position and the ionization degree stays also high 40 μs after the voltage pulse termination.

An update of the spatial and temporal variability of rainfall erosivity (R-factor) for the main agricultural production zones of Austria

Rainfall erosivity is one of the key parameters influencing the degree of soil erosion. Due to the high spatiotemporal variability of rainfall erosivity and the influence of a changing climate it is crucial to use spatially well-distributed and temporally current rainfall data. Rainfall erosivity in Austria has been estimated by previous studies with varying rainfall data amounts. This study aimed to create an updated R-factor map for Austria and its main agricultural production zones based on a larger number of rainfall stations and a recent time series. As well as, compare R-factors from previous studies to identify differences in erosivity estimation. Rainfall data from 171 stations throughout Austria were gap-filled and corrected to improve data quality. Rainfall erosivity was calculated for 1995–2015 for the vegetation period and annually and used to establish two linear regressions describing rainfall erosivity as a function of mean rainfall amount. The regressions were applied to the 1 km2 daily rainfall grids from the SPARTACUS dataset to create the spatially distributed rainfall erosivity maps. Differences in the temporal and spatial distribution of rainfall erosivity, erosion index and erosivity density between the main agricultural production zones showed areas at risk of soil erosion and timing of vulnerability. The highest rainfall erosivities were found in the agriculturally important eastern regions of Austria during the summer months. Compared to previous studies, considerable differences in local R-factor estimation were found. The significantly larger number of rainfall stations and an updated time series increased the representativeness of rainfall erosivity estimation in Austria, which can contribute to a more precise soil erosion risk assessment.

A biogeographical assessment of deep-sea coral assemblages from coastwide visual surveys off California

During the period 1992–2014, we quantified 79,233 deep-sea corals (DSC; azooxanthellate corals occurring in cold or deep waters, generally >50 m) at depths 23–867 m from 1281 visual transects in areas of rocky substrata off northern, central, and southern California. DSC were present on 68% of transects at all depths and substrata types. Thirty-nine taxa and morphotypes from at least 19 families and 24 genera, including 20 species, were identified. Survey depths differed among study regions, overlapping between north and south at >575 m, and between central and south at <325 m. Within study regions, we examined taxa-specific depth and temperature ranges and quantified the spatial distribution of DSC densities. Across study regions, we interpreted species distributions in the context of the literature and biogeographic provinces off California, examined size distributions, and characterized assemblages relative to latitude and depth. We discovered depth range extensions for seven species, and provide the first taxa-specific in situ temperature data for the U.S. West Coast. Overall densities (number of colonies/100 m2) of DSC within study regions were 105.8 (north), 5.0 (central), and 7.3 (south), and highest densities occurred on mixed and hard substrata. We did not observe a change in density with depth. Density ‘hot’ spots (p < 0.05) were identified at multiple locations in the central and south regions for DSC (other than sea pens) and for sea pens, respectively. Despite survey depth differences, three species with large depth ranges were observed in all three study regions, and most species were observed in the biogeographical province(s) reported for them in the literature. Most DSC were ≤20 cm high and ≤10 cm wide; colonies >50 cm high and >40 cm wide were rare and found primarily in the south. Six DSC assemblages (p < 0.05) were identified. Mid-depth assemblages in the central and south differed considerably, while deep assemblages in the north and south were similar. A shallow assemblage comprised taxa shared by central and south regions. As the relative habitat value of DSC to fishes becomes more apparent, our results will provide invaluable information for the identification of essential fish habitat and priority areas in need of protection.

Ecosystem organic carbon storage and their drivers across the drylands of China

Earth’s drylands store large amounts of organic carbon and thus play an important role in regulating atmospheric CO2 concentrations and mitigating climate change. However, little is known about the magnitude and the drivers of organic carbon stocks because of limited data, in particular in desert ecosystems. To fill this gap, we surveyed 763 plots and collected 5091 soil samples from 170 sites covering grassland and desert ecosystems across the drylands of China. The results show that 10.96 Pg organic carbon is stored in these ecosystems (7.07 Pg in grasslands and 3.89 Pg in deserts). The effects of environmental variables on carbon density were found to be contingent on ecosystem type and soil depth. Mean annual precipitation had a strong positive effect on the spatial distributions of vegetation carbon density in both types of ecosystems. The spatial variations of surface (0–40 cm) and subsurface (40–100 cm) soil organic carbon (SOC) density in grasslands were mainly correlated with plant productivity and mean annual temperature (MAT), respectively, while in desert ecosystems, they were mainly correlated with soil salinity (electrical conductivity). The spatial sensitivities (linear regression slopes) of the surface SOC density versus MAT increased from dry subhumid to semi-arid regions and then gradually shifted to decrease from semi-arid to hyper-arid regions, indicating that the surface SOC stock is more sensitive to temperature in semi-arid regions. This study provides a comprehensive survey of ecosystem carbon stocks in China’s drylands, fills a gap in our knowledge about carbon stocks in deserts, complements estimates of ecosystem carbon stocks throughout China, and provides insights into our understanding of the carbon cycle in drylands.

Design and optimization of a microfluidic-based inductor used as a multifunction-sensor

A planar miniaturized inductor has been designed in order to realize some transduction functions linked to the presence of fluids. Its electrical behaviour has been studied for two liquids: Galinstan and salted water. Their presence between metallic armatures modifies the inductance value at a nominal frequency, chosen at 2GHz. By using a FEM software, the spatial distributions of magnetic field and surface current density in the entire device have been modelized for six arbitrary positions of these liquids in inductor microchannels. The geometrical aspects of the device have been studied and their influence examined for each liquid. We show that the inductor performances are influenced by the spiral width variations and the inter-turn distances of the coil. Considering the device as a sensor, we have evaluated the variations of two parameters: inductance and quality factors, which can respectively attain 664% (for gallistan) and 175% (for salted water) from their nominal values.

Mutual coherent structures for heat and angular momentum transport in turbulent Taylor-Couette flows

When subjected to a radial temperature gradient, Taylor-Couette flows undergo evolution of flow states with increasing rotations: a first transition from asymmetric vertical convection to spiral vortices, and a second transition to turbulence characterized by Taylor vortices. In the latter turbulent flow state, the radial transport of heat and angular momentum exhibits a similar power-law scaling. Our data analysis of the spatial distributions of the flux densities reveals mutual turbulent structures through which both heat and angular momentum are transported efficiently.

Designing and the Pilot Trial of Bivalve Molluscan Fishing Quotas on Maoming Coastal Waters of China, Northern South China Sea

In the context of the declining fishery resources, some active management measures have been taken to strive for the sustainable development of fisheries. However, these input-oriented control management measures have not realized the expectation in alleviating the depressing depletion of fishery resources. The fishing quota (FQ) system, an output-oriented control management method, has been proved to be effective in curbing overfishing and conserving fishery resources. However, it has not been formally implemented in China until now. Thus, it is urgent to start the pilot trial on the implementation of the FQ system in China. We firstly formulated a framework for the FQ system on bivalve fisheries and then conducted an empirical analysis based on the field survey of bivalve mollusks in Maoming shallow waters, Guangdong, northern South China Sea. The species composition, dominant species, and density distribution of bivalves were analyzed. The swept-area method was used to assess the total allowable catch (TAC) of bivalves. Each step of the FQ system was discussed in depth. Results showed that a total of 45 bivalve species were identified. Meretrix planisulcata and Ruditapes philippinarum were the two dominant species. The spatial distribution of density varied largely. The estimated TAC value is 4.28 × 105 kg which can be allocated to fishermen under the regulations of the FQ system. Finally, the framework for the FQ system was improved in every step of the future procedure, including target species selection, TAC determination, quota allocation, catch report, and fishing supervision. The general framework of the FQ system in this study can also be referenced to other economically important fish or other marine organisms.

Analytical model of a short DC glow discharge in the presence of significant radial ambipolar diffusion losses

We present a simple analytical model of a short direct-current glow discharge (without positive column) that is applicable for the case of narrow discharge tubes when radial losses of charged particles due to ambipolar diffusion significantly influence discharge properties. The model is based on the analytical parameterization of the non-local ionization produced by fast electrons, which allows obtaining an exact solution of the ambipolar diffusion equation with radial particle losses written in the τ-approximation. Analysis of the spatial distribution of electron density in the near-cathode plasma regions of a discharge allow obtaining an explicit expression for the position of electric field reversal in the negative glow that is independent of electron temperature and interelectrode distance. The latter fact makes the model viable for description of near-cathode plasma regions in the general case of a discharge with a positive column. The procedure for obtaining quantitative estimates and interpretation of experimental data on discharge properties using the proposed model is presented and discussed in detail.

Energy approach in the study of plasma structures of a high-pressure microwave discharge

The energy characteristics of a plasma channel (filament) are the most important for a number of applications. A numerical study of the evolution of the thin plasma channel in air in the range of discharge parameters P = 30–750 Torr and λ = 2.3–8.5 cm showed that the total absorbed energy (Joule's losses) at each time instant is close to its upper estimate, which integrally depends only on the spatial distribution of the plasma density at this instant. A simple analytical expression is obtained for estimating the fraction of the wave beam energy transferred to the channel. An express method for estimating the energy characteristics of a plasma filament is proposed. The method is based on analytical expressions and experimental data on the temporal evolution of the plasma dimensions visible in photographs. The considered example shows the possibility of fast estimation of the total absorbed energy, as well as the specific energy and gas heating in the center of the channel during a microwave pulse.

Spatially explicit estimation of soil organic carbon stock of an estuarine mangrove wetland of eastern India using elemental analysis and very-fine resolution satellite data

BackgroundThis study estimated the total soil organic C (SOC) stock of the wetland influence zone of Bichitrapur mangroves in eastern India in a spatially explicit manner. Both spatial and vertical distribution of SOC densities with respect to land use/land cover (LULC) pattern were assessed. Subsequently, some site-specific management strategies were forwarded towards enhancement of C sequestration potential.MethodsThe changing patterns of LULC within the wetland influence zone of the site were analyzed using Landsat TM (30 m) and Pleiades-1A (2 m) imageries from 1988 to 2018. Point-specific SOC measurement was done using samples taken from four core-depth intervals (viz. D1: 0–20 cm, D2: 20–40 cm, D3: 40–70 cm, D4: 70–100 cm) at 89 locations belonging to different LULC categories. Spatial interpolation was applied on this point-based data to produce SOC density and stock models as a whole and at all core-depths. Relationships between SOC density, core-depth and present LULC were evaluated through multivariate statistical analyses.ResultsThe LULC transformations during last three decades suggested the gradual growth of mangrove plantations as well as agricultural and aquacultural activities. Most amount of SOC was concentrated in D1 (37.17%) followed by D3 (26.51%), while D4 had the lowest (10.87%). The highest mean SOC density was observed in the dense mangrove patches (248.92 Mg ha−1) and the lowest mean was in the Casuarina plantations (2.78 Mg ha−1). Here, Spline method emerged as the best-fit interpolation technique to model SOC data (R2 = 0.74) and estimated total SOC stock of the entire wetland influence zone as 169,569.40 Mg and the grand mean as 125.56 Mg ha−1. Overall, LULC was inferred as a major determinant of SOC dynamics with a statistically significant effect (p < 0.001), whereas no such inference could be drawn for soil core-depth.ConclusionsThe C sequestration potential of sites such as the present one could be increased with appropriate zone-wise plantation strategies, restriction on the land conversion to aquaculture and promotion of ecotourism. Periodic monitoring through integration of geospatial techniques and elemental analyses would be immensely beneficial in this regard.Graphic