479 research outputs found

    The Importance of Space Radiation Shielding Weight

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    The shielding weights required to protect astronauts against space radiation should be considered in relation to the weights of the meteoroid shielding and the life support systems. Comparisons have been carried out for a variety of crew sizes and mission durations. The radiation shield weights were based upon a 1percent probability and were obtained from Webber's data on solar proton events. A mission dose of 100 rad was used as the allowed limit. The doses allowed from solar events were reduced by 45 mrad/day due to galactic radiation and by the amount of radiation expected for two high thrust trips through the earth's trapped radiation belts. In the calculation of the shield weights, the "storm cellar" concept was employed, allotting 50 ft a per man. The meteoroid shield weights were based upon the work of Bjork and the NASA-Ames Research Center criterion. The single shield thicknesses calculated were modified to take into account the reduced penetration where two facing sheets with space between them are used as the meteoroid shield. A percent probability of penetration was assumed in the calculations. The weights of the life support system are dependent upon the assumptions made regarding the particular subsystems to use for a specific mission. Two systems were used for this comparison. The system selected for the 30-day mission provides for body waste storage rather than reprocessing. Each system assumes a cabin leakage rate of 10 Ibs/day and a power penalty weight of 320 lbs/kWe

    Daytime Amphibian Surveys in Three Protected Areas in the Western Great Lakes

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    We performed pilot monitoring of amphibian populations at Apostle Islands National Lakeshore (APIS) in 2006, Pictured Rocks NationalLakeshore (PIRO) in 2007, and Sleeping Bear Dunes National Lakeshore (SLBE ) in both 2006 and 2007. We performed daytime surveys (using multiple methods) at numerous sites in each of the three parks. We detected 10 amphibian and two reptilian species at APIS, nine amphibian and four reptilian species at SLBE , and nine amphibian and one reptilian species at PIRO. No one daytime survey technique appeared to be superior to any other. Our work resulted in two new species records (Gray Treefrog and Green Frog) for Basswood Island at APIS

    Daytime Amphibian Surveys in Three Protected Areas in the Western Great Lakes

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    We performed pilot monitoring of amphibian populations at Apostle Islands National Lakeshore (APIS) in 2006, Pictured Rocks NationalLakeshore (PIRO) in 2007, and Sleeping Bear Dunes National Lakeshore (SLBE ) in both 2006 and 2007. We performed daytime surveys (using multiple methods) at numerous sites in each of the three parks. We detected 10 amphibian and two reptilian species at APIS, nine amphibian and four reptilian species at SLBE , and nine amphibian and one reptilian species at PIRO. No one daytime survey technique appeared to be superior to any other. Our work resulted in two new species records (Gray Treefrog and Green Frog) for Basswood Island at APIS

    An evaluation of risk-based monitoring in pragmatic trials in UK Clinical Trials Units

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    Background Good Clinical Practice guidelines issued in 2016 encourage risk-based approaches to monitoring clinical trials. This study compared current risk assessment and monitoring approaches in UK Clinical Trials Units (CTUs) with the published guidance and makes recommendations for risk-based monitoring in pragmatic trials. Methods An online survey of UK Clinical Research Collaboration registered CTUs was administered via email invitation. Forty-nine units were invited, and 23 responded. Respondents were also invited to share copies of risk assessment templates. Results Most CTUs reported using remote combined with on-site monitoring. All reported undertaking a risk assessment for Clinical Trials of Investigational Medicinal Products (CTIMPs) and 21 units did so for non-CTIMPs. Most CTIMP risk assessments used MHRA (Medicines and Healthcare products Regulatory Agency) classifications, although some also employed staff judgement. Almost all units based their monitoring on perceived risk level; this number was higher for CTIMPs (n = 22) than for non-CTIMPs (n = 19). In most cases, monitoring plans were produced. More CTUs revisited risk assessments during trials in CTIMPs (n = 21) than in non-CTIMPs (n = 18). Small numbers of units reviewed the monitoring approach always (n = 4) or sometimes (n = 9) and few used the reflection to guide future monitoring. Conclusions A high proportion of UK CTUs are using risk-based monitoring in the UK, as recommended by guidelines, for both CTIMPs and non-CTIMPs. This has the potential to make trials more efficient and reduce costs. However, there appears to be a lack of reflection on the value of these revised approaches. There may be a benefit in CTUs collaborating nationally to improve processes for reflection and making changes during the life course of a trial

    Social–ecological mismatches create conservation challenges in introduced species management

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    This is the final version. Available from the Ecological Society of America via the DOI in this recordIntroduced species can have important effects on the component species and processes of native ecosystems. However, effective introduced species management can be complicated by technical and social challenges. We identify “social–ecological mismatches” (that is, differences between the scales and functioning of interacting social and ecological systems) as one such challenge. We present three case studies in which mismatches between the organization and functioning of key social and ecological systems have contributed to controversies and debates surrounding introduced species management and policy. We identify three common issues: social systems and cultures may adapt to a new species’ arrival at a different rate than ecosystems; ecological impacts can arise at one spatial scale while social impacts occur at another; and the effects of introduced species can spread widely, whereas management actions are constrained by organizational and/or political boundaries. We propose strategies for collaborative knowledge building and adaptive management that may help address these challenges

    Monitoring temporal change in riparian vegetation of Great Basin National Park

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    Disturbance in riparian areas of semiarid ecosystems involves complex interactions of pulsed hydrologic flows, herbivory, fire, climatic effects, and anthropogenic influences. We resampled riparian vegetation within ten 10-m × 100-m plots that were initially sampled in 1992 in 4 watersheds of the Snake Range, east central Nevada. Our finding of significantly lower coverage of grasses, forbs, and shrubs within plots in 2001 compared with 1992 was not consistent with the management decision to remove livestock grazing from the watersheds in 1999. Change over time in cover of life-forms or bare ground was not predicted by scat counts within plots in 2001. Cover results were also not well explained by variability between the 2 sampling periods in either density of native herbivores or annual precipitation. In contrast, Engelmann spruce (Picea engelmannii) exhibited reduced abundance at all but the highest-elevation plot in which it occurred in 1992, and the magnitude of change in abundance was strongly predicted by plot elevation. Abundance of white fir (Abies concolor) individuals increased while aspen (Populus tremuloides) individuals decreased at 4 of 5 sites where they were sympatric, and changes in abundance in the 2 species were negatively correlated across those sites. Utility of monitoring data to detect change over time and contribute to adaptive management will vary with sample size, observer bias, use of repeatable or published methods, and precision of measurements, among other factors

    Prediction of milk protein concentration from elements of the metabolizable protein system

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    Elements of the metabolizable protein system in the United Kingdom were examined for their suitability as potential predictors of milk protein concentration. Models were based on data from 163 cows offered five forage mixtures for ad libitum intake plus concentrates at 3, 6, or 9 kg/d of dry matter. The models were then tested on a separate data set of 100 cows offered seven forage mixtures for ad libitum intake plus concentrates at 6 kg/d of dry matter. To minimize problems with collinearity, variables were arranged hierarchically; successive elements were components of variables at higher element levels. Variables from different element levels were not used in the same models. Models were constructed using ridge regression to minimize problems with collinearity. The fit and precision of prediction were generally poor because these models did not take into account animal variables. Models using undegradable dietary protein performed slightly better than did those using digestible undegraded protein. The use of slowly degradable protein and quickly degradable protein rather than rumen-degradable protein generally resulted in improvements in prediction. Models using neutral detergent fiber and quickly fermented carbohydrate were better than those using total carbohydrate. We concluded that there was little to be gained from using the elements of the metabolizable protein system considered here for the prediction of milk protein concentration

    A KRT71 Loss-of-Function Variant Results in Inner Root Sheath Dysplasia and Recessive Congenital Hypotrichosis of Hereford Cattle

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    Genodermatoses, such as heritable skin disorders, mostly represent Mendelian conditions. Congenital hypotrichosis (HY) characterize a condition of being born with less hair than normal. The purpose of this study was to characterize the clinicopathological phenotype of a breed-specific non-syndromic form of HY in Hereford cattle and to identify the causative genetic variant for this recessive disorder. Affected calves showed a very short, fine, wooly, kinky and curly coat over all parts of the body, with a major expression in the ears, the inner part of the limbs, and in the thoracic-abdominal region. Histopathology showed a severely altered morphology of the inner root sheath (IRS) of the hair follicle with abnormal Huxley and Henle’s layers and severely dysplastic hair shafts. A genome-wide association study revealed an association signal on chromosome 5. Homozygosity mapping in a subset of cases refined the HY locus to a 690 kb critical interval encompassing a cluster of type II keratin encoding genes. Protein-coding exons of six positional candidate genes with known hair or hair follicle function were re-sequenced. This revealed a protein-changing variant in the KRT71 gene that encodes a type II keratin specifically expressed in the IRS of the hair follicle (c.281delTGTGCCCA; p.Met94AsnfsX14). Besides obvious phenocopies, a perfect concordance between the presence of this most likely pathogenic loss-of-function variant located in the head domain of KRT71 and the HY phenotype was found. This recessive KRT71-related form of hypotrichosis provides a novel large animal model for similar human conditions. The results have been incorporated in the Online Mendelian Inheritance in Animals (OMIA) database (OMIA 002114-9913)
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