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2,287 result(s) for "Peter, Norbert"
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SARS-CoV-2 and West Nile Virus Prevalence Studies in Raccoons and Raccoon Dogs from Germany
Unlike farm animals, wild animals are not subject to continuous health surveillance. Individual projects designed to screen wildlife populations for specific pathogens are, therefore, also of great importance for human health. In this context, the possible formation of a reservoir for highly pathogenic zoonotic pathogens is a focus of research. Two of these pathogens that have received particular attention during the last years are the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), due to its fast global spread and high impact to the human health, and, since its introduction into Germany, the flavivirus West Nile virus (WNV). Especially in combination with invasive vertebrate species (e.g., raccoons (Procyon lotor) and raccoon dogs (Nyctereutes procyonoides) in Germany), risk analysis must be done to enable health authorities to assess the potential for the establishment of new wild life reservoirs for pathogens. Therefore, samples were collected from raccoons and raccoon dogs and analyzed for the presence of SARS-CoV-2 and WNV infections in these populations. Molecular biological and serological data obtained imply that no SARS-CoV-2 nor WNV reservoir has been established in these two wild life species yet. Future investigations need to keep an eye on these invasive carnivore populations, especially since the close contact of these animals to humans, mainly in urban areas, would make animal–human transmission a challenge for human health.
A genetic meta-algorithm-assisted inversion approach: hydrogeological study for the determination of volumetric rock properties and matrix and fluid parameters in unsaturated formations
An evolutionary inversion approach is suggested for the interpretation of nuclear and resistivity logs measured by direct-push tools in shallow unsaturated sediments. The efficiency of formation evaluation is improved by estimating simultaneously (1) the petrophysical properties that vary rapidly along a drill hole with depth and (2) the zone parameters that can be treated as constant, in one inversion procedure. In the workflow, the fractional volumes of water, air, matrix and clay are estimated in adjacent depths by linearized inversion, whereas the clay and matrix properties are updated using a float-encoded genetic meta-algorithm. The proposed inversion method provides an objective estimate of the zone parameters that appear in the tool response equations applied to solve the forward problem, which can significantly increase the reliability of the petrophysical model as opposed to setting these parameters arbitrarily. The global optimization meta-algorithm not only assures the best fit between the measured and calculated data but also gives a reliable solution, practically independent of the initial model, as laboratory data are unnecessary in the inversion procedure. The feasibility test uses engineering geophysical sounding logs observed in an unsaturated loessy-sandy formation in Hungary. The multi-borehole extension of the inversion technique is developed to determine the petrophysical properties and their estimation errors along a profile of drill holes. The genetic meta-algorithmic inversion method is recommended for hydrogeophysical logging applications of various kinds to automatically extract the volumetric ratios of rock and fluid constituents as well as the most important zone parameters in a reliable inversion procedure.
Habitat Mosaics of Sand Steppes and Forest-Steppes in the Ipoly Valley in Hungary
The present study focuses on the mosaic-like occurrences of patches of steppes and fore-steppes in the Pannonian forest-steppe zone. We present the current vegetation, which is maintained including by human landscape use, i.e., grazing and mowing. The area is complex and for this reason it shows the changes in the landscape and differences in the vegetation more diversely. We wanted to answer the questions: Do sand steppes and forest-steppes occur in the Ipoly Valley and what location? What kind of environmental effects influence the species composition on these areas? Besides classic habitat mapping, are the satellite data from Sentinel-2A useful for distinction of different areas? Comparison of vegetation patches was based on the Hungarian habitat classification system (ÁNÉR). Based on satellite images, quantile data of the Normalized Vegetation Index (NDVI) were used for comparison. Based on the result, water bodies and urban areas are clearly distinguishable from other natural habitats. In some natural vegetation types, we found visible differences, such as grasslands, i.e., sandy steppe meadows and shrubby, woody vegetation patches. Sandy vegetation mainly grows on calcareous soils, which appear to be mosaic-like in the landscape on raised alluvials on the patches of past islands and reefs. From open to continuous closed grasslands, these vegetation types mainly grow on lithosoils. New occurrences of Pannonian sandy vegetation were discovered. In the sandy areas along the Ipoly Valley, open sandy grasslands were found, which is where the northernmost known occurrences of this vegetation type are. Besides common sandy grassland species, the vegetation also contains herbs that are typical in loess-grasslands and it is maintained by grazing, similarly to the eastern Pannonian area. This type of grazing can be useful when maintaining the mosaic-like appearance and diversity of the vegetation.
Hydraulic conductivity explored by factor analysis of borehole geophysical data
A multivariate statistical method is presented for providing hydrogeological information on groundwater formations. Factor analysis is applied to borehole logs in Hungary and the USA to estimate the vertical distribution of hydraulic conductivity of rocks intersected by the borehole. Earlier studies showed a strong correlation between a statistical variable extracted by factor analysis and shale volume in primary porosity rocks. Hydraulic conductivity as a related quantity can be derived directly by factor analysis. In the first step, electric and nuclear logs are transformed into factor logs, which are then correlated to hydraulic properties of aquifers. It is shown that a factor explaining the major part of variance of the measured variables is inversely proportional to hydraulic conductivity. By revealing the regression relation between the above quantities, an estimate for hydraulic conductivity can be given along the entire length of the borehole. Synthetic modeling experiments and field cases demonstrate the feasibility of the method, which can be applied both in primary and secondary porosity aquifers. The results of factor analysis show consistence with those of the Kozeny-Carman method and hydraulic aquifer tests. The application of the statistical analysis of well logs together with independent ground geophysical and hydrogeological methods serves a more efficient exploration of groundwater resources.
Do Sandy Grasslands along the Danube in the Carpathian Basin Preserve the Memory of Forest-Steppes?
Research highlights: In the present survey we examined the sandy grasslands appearing in the steppe-forest-steppe vegetation in the central part of the Carpathian Basin along the Danube. Background and objectives: We aimed to answer the following questions: Is it possible to build a picture of the past form of the vegetation through the examination of these vegetation units based on dominant grass taxa? Is Festuca wagneri an element of open grasslands or steppes? According to our hypothesis, these surveys can help reveal the original or secondary woody, shrubby patches through clarifying dominant taxa. Materials and Methods: We studied the grasslands in terms of coenology, putting great emphasis on the dominant Festuca taxa. Based on our preliminary surveys and literature, three vegetation types can be separated based on one single dominant Festuca taxon in each. The survey was conducted in four different locations in the Carpathian Basin. The cover of dominant grass species was used as an indicator value. The pedological background was also examined. Results: F. vaginata grassland is an open vegetation type based on its coenosystematic composition and ecological values. It grows in very weakly developed calcareous soil with sandy texture, with its lowest and highest organic carbon content ranging from 0.2% to 11.3% (0.2%), and the highest carbonate content (11.3%). Where the grasslands were disturbed, F. pseudovaginata and the recently discovered F. tomanii appeared. These taxa were also found in forest patches. The soil under F. pseudovaginata was more developed, in the surface horizon with higher organic carbon content (1.1%) and lower carbonate content (6.9%). The soil profile under F. wagneri developed the most, as the presence of deep and humus rich soil material from deflation and degradation showed. Conclusions: the dominant Festuca taxa of these vegetation types are good indicators of the changes in the vegetation and their ecological background.
Series Expansion-Based Genetic Inversion of Wireline Logging Data
An evolutionary approach is applied to solve the nonlinear well logging inverse problem. In the framework of the proposed interval inversion method, nuclear, sonic, and laterolog resistivity data measured at an arbitrary depth interval are jointly inverted, where the depth variation of porosity, water saturation, and shale volume is expanded into series using Legendre polynomials as basis functions. In the interval inversion procedure, the series expansion coefficients are estimated by using an adaptive float-encoded genetic algorithm. Since the solution of the inverse problem using traditional linear optimization tools highly depends on the selection of the initial model, a heuristic search is necessary to reduce the initial model dependence of the interval inversion procedure. The genetic inversion strategy used in interval inversion seeks the global extreme of the objective function and provides an estimate of the vertical distribution of petrophysical parameters, even starting the inversion procedure from extremely high distances from the optimum. For a faster computational process, after a couple of thousand generations, the genetic algorithm is replaced by some linear optimization steps. The added advantage of using the Marquardt algorithm is the possibility to characterize the accuracy of the series expansion coefficients and derived petrophysical properties. A Hungarian oil field example demonstrates the feasibility and stability of the improved interval inversion method. As a significance, the genetic inversion method does not require prior knowledge or strong restrictions on the values of petrophysical properties and gives highly reliable estimation results practically independent of the initial model and core information.
Level of thermal maturity estimation in unconventional reservoirs using interval inversion and simulating annealing method
This study presents a novel geophysical approach for estimating the level of thermal maturity (LOM) in unconventional hydrocarbon reservoirs using well log data. LOM is a crucial parameter for assessing the hydrocarbon generation potential of source rocks, but it traditionally relies on laboratory measurements of core samples, which can be time-consuming and costly. The proposed method combines two techniques: interval inversion for estimating total organic carbon (TOC) content from well logs and simulated annealing (SA) optimization for deriving LOM from the estimated TOC. The interval inversion method enables accurate TOC estimation by jointly interpreting multiple well logs over depth intervals, overcoming limitations of conventional point-by-point inversion. Using the estimated TOC, the SA algorithm optimizes an energy function related to Passey's empirical TOC-LOM relationship, iteratively finding the optimal LOM value that best fits the well log data. This approach provides a continuous in situ LOM profile along the borehole without requiring core measurements. The effectiveness of the method is demonstrated through case studies on datasets from the North Sea (Norway), the Pannonian Basin (Hungary), and the Kingak Formation (Alaska). The LOM estimates show good agreement with reported maturity levels and allow reliable reservoir characterization. Statistical analysis confirms the robustness and accuracy of the results. By reducing dependence on core data, this integrated inversion-optimization workflow streamlines the reservoir prospecting phase, enhancing operational efficiency. The method holds promising applications across diverse geological settings for cost-effective evaluation of unconventional hydrocarbon plays.
Exploratory Factor Analysis of Wireline Logs Using a Float-Encoded Genetic Algorithm
In the paper, a novel inversion approach is used for the solution of the problem of factor analysis. The float-encoded genetic algorithm as a global optimization method is implemented to extract factor variables using open-hole logging data. The suggested statistical workflow is used to give a reliable estimate for not only the factors but also the related petrophysical properties in hydrocarbon formations. In the first step, the factor loadings and scores are estimated by Jöreskog’s fast approximate method, which are gradually improved by the genetic algorithm. The forward problem is solved to calculate wireline logs directly from the factor scores. In each generation, the observed and calculated well logs are compared to update the factor population. During the genetic algorithm run, the average fitness of factor populations is maximized to give the best fit between the observed and theoretical data. By using the empirical relation between the first factor and formation shaliness, the shale volume is estimated along the borehole. Permeability as a derived quantity also correlates with the first factor, which allows its determination from an independent source. The estimation results agree well with those of independent deterministic modeling and core measurements. Case studies from Hungary and the USA demonstrate the feasibility of the global optimization based factor analysis, which provides a useful tool for improved reservoir characterization.
Anatomical basis of the risk of radial nerve injury related to the technique of external fixation applied to the distal humerus
Purpose Stabilization of humeral shaft and elbow fractures can be achieved with an external-fixator. Reports about nerve injuries associated with this procedure are rare in literature. Purpose of this anatomical study was to examine the relation of the radial nerve to distal humeral half pins. Methods Percutaneous insertion of external-fixator half pins was performed in 20 upper limbs of 20 cadavers, according to established technique, laterally in the distal humerus. Results Dissection of the upper limbs showed radial nerve injury in four of the 40 placed half pins. The proximal half pin impaled the nerve in one case and the distal half pin in three cases. Moreover the nerve was directly in contact with the pins in nine cases (five proximally, four distally). Conclusions Insertion of external-fixator half pins in the distal humerus can easily injure the radial nerve. Thus we advocate a larger skin incision, blunt dissection to the lateral cortex of the humerus and retraction of soft tissue during half pin insertion.