Pulse shape discrimination performance of Inverted Coaxial Ge detectors

We report on the characterization of two inverted coaxial Ge detectors in the context of being employed in future $^{76}$Ge neutrinoless double beta ($0\nu\beta\beta$) decay experiments. It is an advantage that such detectors can be produced with bigger Ge mass as compared to the planar Broad Energy Ge detectors (BEGe) that are currently used in the GERDA $0\nu\beta\beta$ decay experiment. This will result in lower background for the search of $0\nu\beta\beta$ decay due to a reduction of cables, electronics and holders. The measured resolution near the $^{76}$Ge Q-value at 2039 keV is 2.5 keV and their pulse-shape characteristics are similar to BEGe-detectors. It is concluded that this type of Ge-detector is suitable for usage in $^{76}$Ge $0\nu\beta\beta$ decay experiments

Targeted adjustment of residual stresses in hot-formed components by means of process design based on finite element simulation

The aim of this work is to generate an advantageous compressive residual stress distribution in the surface area of hot-formed components by intelligent process control with tailored cooling. Adapted cooling is achieved by partial or temporal instationary exposure of the specimens to a water–air spray. In this way, macroscopic effects such as local plastification caused by inhomogeneous strains due to thermal and transformation-induced loads can be controlled in order to finally customise the surface-near residual stress distribution. Applications for hot-formed components often require special microstructural properties, which guarantee a certain hardness or ductility. For this reason, the scientific challenge of this work is to generate different residual stress distributions on components surfaces, while the geometric as well as microstructural properties of AISI 52100 alloy stay the same. The changes in the residual stresses should therefore not result from the mentioned changed component properties, but solely from the targeted process control. Within the scope of preliminary experimental studies, tensile residual stresses in a martensitic microstructure were determined on reference components, which had undergone a simple cooling in water (from the forming heat), or low compressive stresses in pearlitic microstructures were determined after simple cooling in atmospheric air. Numerical studies are used to design two tailored cooling strategies capable of generating compressive stresses in the same components. The developed processes with tailored cooling are experimentally realised, and their properties are compared to those of components manufactured involving simple cooling. Based on the numerical and experimental analyses, this work demonstrates that it is possible to influence and even invert the sign of the residual stresses within a component by controlling the macroscopic effects mentioned above

The Tails of the Crossing Probability

The scaling of the tails of the probability of a system to percolate only in the horizontal direction $\pi_{hs}$ was investigated numerically for correlated site-bond percolation model for $q=1,2,3,4$.We have to demonstrate that the tails of the crossing probability far from the critical point have shape $\pi_{hs}(p) \simeq D \exp(c L[p-p_{c}]^{\nu})$ where $\nu$ is the correlation length index, $p=1-\exp(-\beta)$ is the probability of a bond to be closed. At criticality we observe crossover to another scaling $\pi_{hs}(p) \simeq A \exp (-b {L [p-p_{c}]^{\nu}}^{z})$. Here $z$ is a scaling index describing the central part of the crossing probability.Comment: 20 pages, 7 figures, v3:one fitting procedure is changed, grammatical change

Habitat, Climate, and Raptors as Factors in the Northern Bobwhite Decline: A Multi-Scale Analysis

Landscape-level processes such as habitat loss and fragmentation are primarily responsible for the declines in northern bobwhite (Colinus virginianus). These landscape processes generally occur at a scale beyond that of traditional quail studies and may involve not only habitat loss and fragmentation but also broad-scale changes in climate trends and predation risk. However, reductions in usable space and changes in habitat configuration at smaller scales may also reduce population viability. It is therefore imperative to study relationships to bobwhite populations at multiple scales. The objective of our research is to quantify to what extent habitat loss and fragmentation, climate, and predators are affecting quail populations at multiple scales within Texas. Our study area will include the Rolling Plains and Rio Grande Plains ecoregions, which are historic strongholds of bobwhite, though each has seen recent declines. We will examine the relative contributions of 3 general factors (habitat, climate, and predators) on quail populations at multiple scales (ranch, route-level, and landscape). Specifically, these factors include total habitat amount, degree of fragmentation, raptor relative abundance, temperature, and precipitation. We will obtain data from multiple sources to determine quail trends (Breeding Bird Survey and ranch-level data) and relate habitat trends (National Land Cover Database and Texas Ecological Systems Classification Project), raptor abundance (Breeding Bird Survey), and climate factors (PRISM) within a multiple linear regression framework. This study will provide an understanding of 1) to what degree habitat loss and fragmentation are affecting quail populations on Texas rangelands, 2) how other factors such as climate and predators may be compounding these effects, and 3) how these relationships vary at multiple scales

Impact of deforestation on habitat connectivity thresholds for large carnivores in tropical forests

Introduction Deforestation significantly impacts large carnivores that depend on large tracts of interconnected forest habitat and that are sensitive to human activities. Understanding the relationship between habitat use and spatial distribution of such species across human modified landscapes is critical when planning effective conservation strategies. This study assessed the presence of potential landscape connectivity thresholds resulting from habitat fragmentation associated with different deforestation patterns using a scale-based approach that links species-specific home ranges with the extent of anthropogenic activities. The objectives were (1) to quantify the spatial and temporal distribution of natural vegetation for five common deforestation patterns and (2) to evaluate the connectivity associated with these patterns and the existence of potential thresholds affecting jaguar dispersal. The Bolivian lowlands, located within jaguar conservation units, were analysed with landscape metrics to capture the spatial and temporal changes within deforested areas and to determine potential impact on jaguar connectivity and connectivity thresholds for dispersal. Results Over the period of 1976–2005, the amount of natural vegetation has decreased by more than 40% in all locations with the biggest changes occurring between 1991 and 2000. Landscape spatial structure around jaguar locations showed that jaguars used areas with mean proportion of natural areas = 83.14% (SE = 3.72%), mean patch density = 1.16 patches/100 ha (SE = 0.28 patches/100 ha), mean patch area = 616.95 ha (SE = 172.89 ha) and mean edge density = 705.27 m/ha (SE = 182.19 m/ha).We observed strong fragmentation processes in all study locations, which has resulted in the connectivity of jaguar habitat decreasing to <20% by 2005. A connectivity threshold zone was observed when the proportion of natural vegetation was less than 58.4% (SE = 1.3). Conclusions Assessing fragmentation and connectivity for carnivores within the extent of human-modified landscapes proved to be an effective way to understand the changes caused by deforestation and their potential effects on large carnivore habitats. Our study highlights the importance of scale-based approaches for assessing current conservation challenges to protect large carnivores

Vegetation and Arthropod Responses to Brush Reduction by Grubbing and Stacking

Grubbing is a mechanical brush-reduction technique that allows targeting of mesquite (Prosopis glandulosa) and huisache (Vachellia farnesiana) and can be used to open lanes for hunting northern bobwhites (Colinus virginianus). Follow-up treatments of stacking allow the piling up of downed brush. We initiated this study on the Santa Gertrudis Division of the King Ranch, Inc., Texas, to determine effects of grubbing and stacking on vegetation and arthropod communities important to bobwhite. We hypothesized that grubbing and stacking would be able to selectively remove mesquite and huisache while leaving mixed brush species largely intact. We hypothesized that soil disturbance treatments would lead to improved brooding, feeding, and nesting habitat for bobwhite through an increase in herbaceous food plants, arthropods, and nesting cover. We sampled vegetation prior to treatment during July 2012 and posttreatment during November 2012, March 2013, and July 2013. We sampled arthropods before treatment in July 2012 and monthly posttreatment until July 2013, a year marked by extreme drought in South Texas. We detected a positive response of bobwhite food grasses and/or sedges 1 year after initial treatments but detected no treatment effect on bobwhite food forbs. We detected no effects of treatments on nesting cover. Grubbing and stacking did not affect total Insecta abundance; however, Insecta biomass and Arachnida abundance and biomass responded both positively and negatively to treatments. To better understand the effects of grubbing and stacking, replication of this study during years of average and above average precipitation should be conducted

Landscape-Scale Effects of Habitat and Weather on Scaled Quail Populations

Scaled quail (Callipepla squamata) have declined over the last half century; however, there is spatial variation within their geographic distribution. Interior populations have increased and peripheral populations have generally decreased. Declines have been attributed to habitat loss and degradation. Scaled quail populations also show interannual fluctuations related to precipitation. Our objective was to determine the relative impact of habitat and weather (i.e., precipitation and temperature) on scaled quail population dynamics. Our hypothesis was that habitat metrics would be more important for decreasing populations whereas weather metrics would be more important for increasing populations. We used publicly available datasets for scaled quail abundance measures (Breeding Bird Survey, Christmas Bird Count), weather (PRISM), and land cover (National Land Cover Data) collected over 3 5-year time periods (1990–1994, 1999–2003, 2009–2013). Data were collected at 2 scales: a route scale (5-km route buffer) and region scale (25-km circular buffer). We developed 25 a priori models that fit into 4 “model classes” (habitat amount, habitat fragmentation, matrix quality, weather). Model selection followed a 2-stage approach, where models were initially evaluated within each individual model class, then top models from each class were evaluated in combination to determine a global model. We used mixed-effects models with a negative binomial response distribution, treating route as a random effect. Weather variables were the primary explanatory factor for increasing populations at both scales. Similarly following our hypothesis, habitat variables were generally the most important for decreasing populations, but only at the route scale; weather variables dominated at the region scale. Both abundance datasets provided similar results and explanatory power (R2 ≈ 0.10 for route scale; R2 ≈ 0.27 for region scale), for both increasing and decreasing populations. Comparisons of land cover variables showed increasing populations to have higher amounts of habitat (p = 0.0028), higher mean patch area of habitat (p = 0.0446), and lower urban cover (p = 0.0287). Our hypothesis that weather variables account for more variation of increasing scaled quail populations was generally supported, likely because of increased amounts of habitat in these areas. However, given the low overall explanatory power of our models, it is likely that other factors such as habitat quality may be more important to scaled quail. Increasing temperature and reduced precipitation associated with climate change are likely to exacerbate scaled quail declines both directly and through continued habitat degradation, even within areas with increasing populations

Can modeling and simulation really help power system designers?

The rap session provided an informal forum for dissemination of information on the state of the art in modeling and simulation of power processing systems. Merits of time domain and frequency domain approaches were debated and the use of these techniques for the prediction of performance and the optimization of a design were discussed. Although it appears that the present state of the art is somethat primative, interest is high and continued progress and improvement should be forthcoming