132 research outputs found
Publication Bias in the Performance Diagnostic Checklist and its Variations
Publication bias—selectively publishing studies with positive outcomes—poses a problem to science as it can lead to inaccurate reports of intervention effects. Sham and Smith (2014) found that the published and unpublished pivotal response treatment literature differed, calling for more investigation into behavior-analytic research for publication bias. In this study, comparisons between the published and unpublished literature on the Performance Diagnostic Checklist, Performance Diagnostic Checklist-Human Services, and the Performance Diagnostic Checklist-Safety were conducted across three effect size measures: percentage of non-overlapping data, improvement rate difference, and percentage of data exceeding the median. Generally published literature outperformed the unpublished literature, providing further evidence of an overselling of results in the field
Habitat Use of Wintering Henslow\u27s Sparrows (Centronyx henslowii) in Power Line Right-of-Ways
Habitat loss and degradation are the leading causes of grassland bird declines worldwide. The Henslow’s Sparrow (Centronyx henslowii; hereafter HESP) is a grassland bird species of conservation concern that has historically relied on the herbaceous ground-layer of longleaf pine savannas and similar habitats in the southeastern U.S. for food and shelter in the winter. However, due to human development, alterations of habitat, and fire suppression, only fragments of these habitats remain. Over the last decade, surveys have annually documented HESPs using power line right-of-ways (hereafter, ROWs) at several sites in the coastal plain of Georgia as alternative habitat for overwintering. These ROWs share similar vegetative characteristics to pine savannas because they are managed to have low tree cover and because they have a graminoid-dominated ground-layer. However, which micro-habitat characteristics HESPs select, and how much space they use within ROWs has not yet been studied. During the winters of 2019 to 2021, I captured HESPs at three Wildlife Management Areas and attached radio-transmitters to track their habitat selection and evaluate space use within ROWs. I conducted vegetation surveys in used and available habitat in the ROWs to assess which vegetation characteristics (e.g., height, density, composition) HESPs select. I used principal component analysis to reduce the number of vegetation variables and look for correlations among variables. I then used conditional logistic regression and model selection to identify top predictors of HESP habitat use. Statistical analyses showed that HESPs select areas within a ROW with a greater number of forb species, a small percentage of woody vegetation for escape refugia, and high vegetation density at the ground level. HESPs used less space (using 0.14 ha on average) than in longleaf pine savanna habitats, based on comparison with the literature. Based on these findings, I recommend habitat management practices that promote forb diversity, increase food resources, and maintain habitat structure. This study shows that ROWs can be important areas for conservation of overwintering HESPs. With continued management, ROWs can support overwintering grassland birds and could potentially act as corridors between longleaf pine restoration sites
Fire effects on aquatic ecosystems: an assessment of the current state of science
Fire is a prevalent feature of many landscapes and has numerous and complex effects on geological, hydrological, ecological, and economic systems. In some regions, the frequency and intensity of wildfire have increased in recent years and are projected to escalate with predicted climatic and landuse changes. In addition, prescribed burns continue to be used in many parts of the world to clear vegetation for development projects, encourage desired vegetation, and reduce fuel loads. Given the prevalence of fire on the landscape, authors of papers in this special series examine the complexities of fire as a disturbance shaping freshwater ecosystems and highlight the state of the science. These papers cover key aspects of fire effects that range from vegetation loss and recovery in watersheds to effects on hydrology and water quality with consequences for communities (from algae to fish), food webs, and ecosystem processes (e.g., organic matter subsidies, nutrient cycling) across a range of scales. The results presented in this special series of articles expand our knowledge of fire effects in different biomes, water bodies, and geographic regions, encompassing aquatic population, community, and ecosystem responses. In this overview, we summarize each paper and emphasize its contributions to knowledge on fire ecology and freshwater ecosystems. This overview concludes with a list of 7 research foci that are needed to further our knowledge of fire effects on aquatic ecosystems, including research on: 1) additional biomes and geographic regions; 2) additional habitats, including wetlands and lacustrine ecosystems; 3) different fire severities, sizes, and spatial configurations; and 4) additional response variables (e.g., ecosystem processes) 5) over long (>5 y) time scales 6) with more rigorous study designs and data analyses, and 7) consideration of the effects of fire management practices and policies on aquatic ecosystems
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Relations among hydrology, soils, and vegetation in riparian meadows : influence on organic matter distribution and storage
Organic matter dynamics in riparian ecosystems are largely driven by interactions
among hydrology, soil, and vegetation. In two riparian meadows, northeast Oregon, I
examined the hypothesis that vegetation and soil characteristics in three plant communities
- defined as wet, moist, and dry meadow - were strongly influenced by hydrological and
redox variables associated with the geomorphological position of each community on the
floodplain. Along short transects that extended from stream-side wet communities to
terrace dry communities, I sampled plant species composition, biomass, and soil;
calculated carbon and nitrogen pools; and monitored water table elevation, soil redox
potential, and dissolved organic carbon (DOC) and nitrate-nitrogen (nitrate-N) in shallow
ground water.
Strong gradients in water table elevation and soil redox potential existed along the
transects.. Water table elevation followed seasonal patterns of stream stage, and was
consistently highest in wet communities, intermediate in moist communities, and lowest in
dry communities. Soil redox potential indicated seasonal anaerobic conditions ([less than or equal to] 300 mV)
in the wet and moist communities, and year-round aerobic conditions in the dry
communities. Plant communities differed markedly in species richness (dry> moist>
wet), total biomass (wet> moist> dry), and ratios of belowground-to-aboveground
biomass (wet> moist> dry). Soil carbon and nitrogen pools were highest in dry
communities and similar in wet and moist communities. Vegetation and soil
characteristics were strongly correlated to median water table elevation and redox
potential. Ecosystem (biomass + soil) carbon ranged from 7.01 to 11.7 kg/m², with [approximately] 2 to
4 % in aboveground biomass, [approximately] 2 to 23% in belowground biomass, and [approximately] 81 to 95% in
soil. Ecosystem nitrogen ranged from 0.035 to 0.093 kg/m², with [approximately] 0.7 to 1.6 % in
aboveground biomass, [approximately] 1.5 to 6 % in belowground biomass, and [approximately] 94 to 98% in soil. In
shallow ground water, concentrations of DOC and nitrate-N were two to six times greater
than in stream water, with highest values in wet communities. Collectively, these results
indicate that, in unconstrained reaches, water table elevation and soil redox potential
strongly influence distribution of plant species, and dynamics and storage of organic
matter
A Noninvasive Method to Detect Mexican Wolves and Estimate Abundance
Monitoring wolf abundance is important for recovery efforts of Mexican wolves (Canis lupus baileyi) in the Blue Range Wolf Recovery Area in Arizona and New Mexico, USA. Although radiotelemetry has been a reliable method, collaring and tracking wolves in an expanding population will be prohibitively expensive and alternative methods to estimate abundance will become necessary. We applied 10 canid microsatellite loci to 235 Mexican wolf samples, 48 coyote (C. latrans) samples, and 14 domestic dog (C. lupus familiaris) samples to identify alleles that provide reliable separation of these species. We then evaluated an approach for prescreening, noninvasively collected DNA obtained from fecal samples to identify Mexican wolves. We generated complete genotypes for only those samples identified as probable Mexican wolves. We used these genotypes to estimate mark–recapture population estimates of Mexican wolves and compared these to known numbers of wolves in the study area.We collected fecal samples during 3 sampling periods in 2007–2008 and used Huggins-type mark–recapture models to estimate Mexican wolf abundance. We were able to generate abundance estimates with 95% confidence for 2 of 3 sampling periods. We estimated abundance to be 10 (95% Cl = 6–34) during one sampling period when the known abundance was 10 and we estimated abundance to be 9 (95% CI = 6 –30) during the other sampling period when the known abundance was 10. The application of this noninvasive method to estimate Mexican wolf abundance provides an alternative monitoring tool that could be useful for long-term monitoring of this and other recovering populations. Published 2016. This article is a U.S. Government work and is in the public domain in the USA
A Noninvasive Method to Detect Mexican Wolves and Estimate Abundance
Monitoring wolf abundance is important for recovery efforts of Mexican wolves (Canis lupus baileyi) in the Blue Range Wolf Recovery Area in Arizona and New Mexico, USA. Although radiotelemetry has been a reliable method, collaring and tracking wolves in an expanding population will be prohibitively expensive and alternative methods to estimate abundance will become necessary. We applied 10 canid microsatellite loci to 235 Mexican wolf samples, 48 coyote (C. latrans) samples, and 14 domestic dog (C. lupus familiaris) samples to identify alleles that provide reliable separation of these species. We then evaluated an approach for prescreening, noninvasively collected DNA obtained from fecal samples to identify Mexican wolves. We generated complete genotypes for only those samples identified as probable Mexican wolves. We used these genotypes to estimate mark–recapture population estimates of Mexican wolves and compared these to known numbers of wolves in the study area.We collected fecal samples during 3 sampling periods in 2007–2008 and used Huggins-type mark–recapture models to estimate Mexican wolf abundance. We were able to generate abundance estimates with 95% confidence for 2 of 3 sampling periods. We estimated abundance to be 10 (95% Cl = 6–34) during one sampling period when the known abundance was 10 and we estimated abundance to be 9 (95% CI = 6 –30) during the other sampling period when the known abundance was 10. The application of this noninvasive method to estimate Mexican wolf abundance provides an alternative monitoring tool that could be useful for long-term monitoring of this and other recovering populations. Published 2016. This article is a U.S. Government work and is in the public domain in the USA
Risk Based Analysis and Design af Stiffened Plates
The traditional Risk Based Design (RBD) process involves designing a structure based on risk estimates obtained during several iterations of an optimization routine. This approach is computationally expensive for large-scale aircraft structural systems. The main objective of this research is to establish a RBD algorithm and produce RBD plots for stiffened plates. Basic steps to check functionality will be done by first analyzing a flat plate for which closed formed equations are available and then moving to more complex geometries like stiffened plates.
Therefore, the concept of RBD plots that can be used for both structural sizing and risk assessment are introduced. RBD plots serve as a tool for failure probability assessment given geometry and applied load and can also be used to determine geometric constraints to be used in sizing given allowable failure probability. This approach transforms a reliability-based optimization problem into a deterministic optimization problem with geometric constraints
A study of pressure drop in helical coils.
This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known. Â It has been included in the digital archive for its historical value to NPS. Â Not believed to be a CIVINS (Civilian Institutions) title.http://www.archive.org/details/studyofpressured00dwirU.S. Navy (U.S.N.) author
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