1,330 research outputs found

    Variations in Vegetation and Microclimate on North- and South-Facing Slopes in the Mixed Prairie near Hays, Kansas

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    North- and south-facing slopes were studied to determine differences in vegetation and microclimate. Vegetation was analyzed by line transects. The study on microclimate included soil and air temperatures, evaporation, light intensities, and wind velocities. Appropriate instruments were used for each microclimatic factor, and were identical on both slopes. The microclimate on north- facing slopes was less intense and severe than on south-facing slopes, resulting in a difference in vegetation. The protected position of the north-facing slope has provided a habitat which is favorable to more mesophytic plants. In contrast, the exposed position of the south-facing slope has limited the vegetation to more xerophytic species. Big bluestem (Andropogon gerardi) and little bluestem (A. scoparius) were the dominant grasses on the north- facing slope, whereas, buffalo grass (Buchloe dactyloides), blue grama (Bouteloua gracilis), and side-oats grama (B. curtipendula) were dominant on the south-facing slope. Several species of forbs were restricted to, or were much more abundant on one slope or the other. Woody species were common on north-facing slopes, but were seldom found on south-facing slopes. Seasonal averages of microclimatic conditions are as follows: Evaporation rates were 88.51 mI. per week more on the south-facing slope. Wind velocities were 3.33 MPH faster on south exposures and were closely correlated with evaporation. Soil temperatures on the north-facing slope averaged 11.23 deg. F. cooler at 1-inch depth, and 10.20 deg. F. cooler at 6-inch depth. Maximum air temperatures were 88.25 deg. F. for the south-facing slope and 85.77 deg. F. for the north-facing slope. Minimum air temperatures were 61.65 deg. F. for south exposures, and 60.04 deg. F. for north exposures. Light intensities averaged 4068.86 foot candles at ground level, and 4693.15 foot candles above the vegetation on the south-facing slope, compared to 2927.60 foot candles at ground level and 3632.2 foot candles above the vegetation on the north-facing slope. Yields of forage on the north-facing slope were 1,727.7 pounds per acre, compared to 838.1 pounds per acre on the south-facing slope. Mid grasses contributed most to yields on the north-facing slope, whereas, short grasses provided the largest part of the yield on the south-facing slope

    Distributed Queries for Quality Control Checks in Clinical Trials

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    Operational Quality Control (QC) checks are standard practice in clinical trials and ensure ongoing compliance with the study protocol, standard operating procedures (SOPs) and Good Clinical Practice (GCP). We present a method for defining QC checks as distributed queries over case report forms (CRF) and clinical imaging data- sources. Our distributed query system can integrate time-sensitive information in order to populate QC checks that can facilitate discrepancy resolution workflow in clinical trials

    Testing metapopulation concepts: effects of patch characteristics and neighborhood occupancy on the dynamics of an endangered lagomorph

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    Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model selection to identify important drivers of population turnover and estimate the effective neighborhood size for this system. Several key relationships related to patch size and isolation that are often assumed in metapopulation models were supported: patch size was negatively related to the probability of extinction and positively related to colonization, and estimated occupancy of neighboring patches was positively related to colonization and negatively related to extinction probabilities. This latter relationship suggested the existence of rescue effects. In our study system, we inferred that coastal patches experienced higher probabilities of extinction and colonization than interior patches. Interior patches exhibited higher occupancy probabilities and may serve as refugia, permitting colonization of coastal patches following disturbances such as hurricanes and storm surges. Our modeling approach should be useful for incorporating neighbor occupancy into future metapopulation analyses and in dealing with other historic occupancy surveys that may not include the recommended levels of sampling replication

    Testing metapopulation concepts: effects of patch characteristics and neighborhood occupancy on the dynamics of an endangered lagomorph

    Get PDF
    Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model selection to identify important drivers of population turnover and estimate the effective neighborhood size for this system. Several key relationships related to patch size and isolation that are often assumed in metapopulation models were supported: patch size was negatively related to the probability of extinction and positively related to colonization, and estimated occupancy of neighboring patches was positively related to colonization and negatively related to extinction probabilities. This latter relationship suggested the existence of rescue effects. In our study system, we inferred that coastal patches experienced higher probabilities of extinction and colonization than interior patches. Interior patches exhibited higher occupancy probabilities and may serve as refugia, permitting colonization of coastal patches following disturbances such as hurricanes and storm surges. Our modeling approach should be useful for incorporating neighbor occupancy into future metapopulation analyses and in dealing with other historic occupancy surveys that may not include the recommended levels of sampling replication

    Genotype and Genotype x Environment Interaction Effects on Forage Yield and Quality of Intermediate Wheatgrass in Swards

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    Genetic differences among cultivars or strains for specific traits can be significantly reduced or increased by differential genotypic responses to environments. The objective of this study was to determine the relative magnitude of genotype and genotype x environment interaction effects, which are due to differential responses, on forage yield and quality of intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] when grown in seeded swards in the central Great Plains. Thirty-four strains (genotypes), which included cultivars, experimental strains, and PI lines, were grown in replicated trials at Mead, North Platte, and Alliance, NE. The three sites differed markedly in precipitation and length of growing season. There were significant differences among strains for all evaluated traits. Genotype x location and genotype x year interaction effects were not significant for in vitro dry matter digestibility (IVDMD), indicating that this trait is quite stable across environments. Genotype x location interaction effects were significant for forage yield and protein concentration; genotype x year effects were significant for forage yield. Spearman rank correlations, used to test for consistency of ranking of the strains across environments, were high and significant for IVDMD, but were low and usually not significant for forage yield. Improving IVDMD should be emphasized in intermediate wheatgrass breeding programs, since there is substantial genetic variation for IVDMD, it is stable across environments, and it can improve livestock production per hectare

    The Values of Warm-Season Native Perennial Grasses Grown for Pasture or Biofuel in the Southern Great Plains, USA

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    The Renewable Fuel Standard under the Energy Independence and Security Act of 2007 mandated the production of 136 billion liters of cellulosic biofuel by 2022. Switchgrass (Panicum virgatum) has been identified as a primary feedstock because it is a perennial, produces high yields and is adapted to a wide environmental range. Development of the cellulosic biofuel industry has been slow. A reason for this slow development is lack of available feedstock driven by lack of a developed market. Rather than considering switchgrass only as a dedicated biofuel feedstock, we examined its potential both for grazing and biofuel feedstock. In a series of experiments testing yield, grazing preference and animal gain; switchgrass (cv. Alamo) was found to produce greater total yield (17696 kg/ha) than fifteen other warm season perennial grasses, was the most preferred by stocker cattle in a grazing preference study and produced average daily gains in a grazing study (0.84-1.05 kg/hd). These results demonstrate the potential of switchgrass for both grazing and biofuel feedstock. However, the feedstock price would need to increase above $91/t before the economics of dedicated switchgrass feedstock production would surpass that of a combination of switchgrass grazing and feedstock production

    Spatial Patch Occupancy Patterns of the Lower Keys Marsh Rabbit

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    Reliable estimates of presence or absence of a species can provide substantial information on management questions related to distribution and habitat use but should incorporate the probability of detection to reduce bias. We surveyed for the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) in habitat patches on 5 Florida Key islands, USA, to estimate occupancy and detection probabilities. We derived detection probabilities using spatial replication of plots and evaluated hypotheses that patch location (coastal or interior) and patch size influence occupancy and detection. Results demonstrate that detection probability, given rabbits were present, was \u3c0.5 and suggest that naı¨ve estimates (i.e., estimates without consideration of imperfect detection) of patch occupancy are negatively biased. We found that patch size and location influenced probability of occupancy but not detection. Our findings will be used by Refuge managers to evaluate population trends of Lower Keys marsh rabbits from historical data and to guide management decisions for species recovery. The sampling and analytical methods we used may be useful for researchers and managers of other endangered lagomorphs and cryptic or fossorial animals occupying diverse habitats

    DSL ligand endocytosis physically dissociates Notch1 heterodimers before activating proteolysis can occur

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    Cleavage of Notch by furin is required to generate a mature, cell surface heterodimeric receptor that can be proteolytically activated to release its intracellular domain, which functions in signal transduction. Current models propose that ligand binding to heterodimeric Notch (hNotch) induces a disintegrin and metalloprotease (ADAM) proteolytic release of the Notch extracellular domain (NECD), which is subsequently shed and/or endocytosed by DSL ligand cells. We provide evidence for NECD release and internalization by DSL ligand cells, which, surprisingly, did not require ADAM activity. However, losses in either hNotch formation or ligand endocytosis significantly decreased NECD transfer to DSL ligand cells, as well as signaling in Notch cells. Because endocytosis-defective ligands bind hNotch, but do not dissociate it, additional forces beyond those produced through ligand binding must function to disrupt the intramolecular interactions that keep hNotch intact and inactive. Based on our findings, we propose that mechanical forces generated during DSL ligand endocytosis function to physically dissociate hNotch, and that dissociation is a necessary step in Notch activation

    Neuroanatomical Domain of the Foundational Model of Anatomy Ontology

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    Background: The diverse set of human brain structure and function analysis methods represents a difficult challenge for reconciling multiple views of neuroanatomical organization. While different views of organization are expected and valid, no widely adopted approach exists to harmonize different brain labeling protocols and terminologies. Our approach uses the natural organizing framework provided by anatomical structure to correlate terminologies commonly used in neuroimaging. Description: The Foundational Model of Anatomy (FMA) Ontology provides a semantic framework for representing the anatomical entities and relationships that constitute the phenotypic organization of the human body. In this paper we describe recent enhancements to the neuroanatomical content of the FMA that models cytoarchitectural and morphological regions of the cerebral cortex, as well as white matter structure and connectivity. This modeling effort is driven by the need to correlate and reconcile the terms used in neuroanatomical labeling protocols. By providing an ontological framework that harmonizes multiple views of neuroanatomical organization, the FMA provides developers with reusable and computable knowledge for a range of biomedical applications. Conclusions: A requirement for facilitating the integration of basic and clinical neuroscience data from diverse sources is a well-structured ontology that can incorporate, organize, and associate neuroanatomical data. We applied the ontological framework of the FMA to align the vocabularies used by several human brain atlases, and to encode emerging knowledge about structural connectivity in the brain. We highlighted several use cases of these extensions, including ontology reuse, neuroimaging data annotation, and organizing 3D brain models

    FishFace: interactive atlas of zebrafish craniofacial development at cellular resolution

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    Background: The vertebrate craniofacial skeleton may exhibit anatomical complexity and diversity, but its genesis and evolution can be understood through careful dissection of developmental programs at cellular resolution. Resources are lacking that include introductory overviews of skeletal anatomy coupled with descriptions of craniofacial development at cellular resolution. In addition to providing analytical guidelines for other studies, such an atlas would suggest cellular mechanisms underlying development. Description We present the Fish Face Atlas, an online, 3D-interactive atlas of craniofacial development in the zebrafish Danio rerio. Alizarin red-stained skulls scanned by fluorescent optical projection tomography and segmented into individual elements provide a resource for understanding the 3D structure of the zebrafish craniofacial skeleton. These data provide the user an anatomical entry point to confocal images of Alizarin red-stained zebrafish with transgenically-labelled pharyngeal arch ectomesenchyme, chondrocytes, and osteoblasts, which illustrate the appearance, morphogenesis, and growth of the mandibular and hyoid cartilages and bones, as viewed in live, anesthetized zebrafish during embryonic and larval development. Confocal image stacks at high magnification during the same stages provide cellular detail and suggest developmental and evolutionary hypotheses. Conclusion: The FishFace Atlas is a novel learning tool for understanding craniofacial skeletal development, and can serve as a reference for a variety of studies, including comparative and mutational analyses
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