204 research outputs found

    Dual solid cryogens for spacecraft refrigeration Patent

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    Dual solid cryogens for spacecraft refrigeration insuring low temperature cooling for extended period

    Design and construction of an engineering model solid cryogen refrigerator for infrared detector cooling at 50 deg K

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    Design and construction of prototype spacecraft cryogenic refrigerator for infrared detector coolin

    Study on high performance insulation thermal design criteria Quarterly progress report

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    Diffusion coefficients, outgassing studies, and correlation of complete system thermal model computer program predictions with 82.6 inch tank test dat

    Development of dual solid cryogens for high reliability refrigeration system

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    High reliability solid cryogen refrigeration system consists of a container initially filled with a solid cryogen which is coupled thermally to an infrared detector by means of a link of high thermal conductivity extending from a heat exchanger within the cryogen container

    Combined in situ experimentation and modelling approaches to disentangle processes involved in the earliest stage of community assembly

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    The ecological process of community assembly is described as the succession of three phases: colonization, regulation and segregation. Early colonization remains the least studied and quantified phase of assembly. In order to fill this gap, an approach combining in situ experiments and modelling was proposed to study colonization by a benthic macrofauna community in open microcosms containing a single, non-limiting resource. The experiment was three months long. A total of 51 taxa were observed in the microcosms, but data analyses of the species composition and abundances revealed that five species, Capitella spp., Gammaropsis maculata, Erichtionus punctatus, Nereiphylla paretti and Harmothoe mariannae, explained most of the observed variation in the assembly process. The population dynamics of these species were simulated taking into account functional traits that govern individual interactions. The dynamic model simulated a demographic stochasticity due to low population densities that result from the small size of the experimental microcosms. Using this combined approach of experiments and modelling, we showed that predation interactions alone can account for the abundances and species composition of primary consumers during the transient phase of early colonization

    Integrated pest management strategies for cabbage stem flea beetle (Psylliodes chrysocephala) in oilseed rape

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    Oilseed rape (OSR) is the second largest source of vegetable oil globally and the most important biofuel feedstock in the European Union (EU) but production of this important crop is threatened by a small insect; Psylliodes chrysocepaha – the cabbage stem flea beetle (CSFB). The EU ban on use of neonicotinoid seed treatments and resistance of CSFB to pyrethroid insecticides have left farmers with limited control options resulting in drastic reductions in production. Integrated pest management (IPM) may offer a solution. We review the lifecycle of CSFB and the current options available, or in the research pipeline, for the eight IPM principles of the EU Sustainable Use of Pesticides Directive (Directive-2009/128/EC). A full IPM strategy for CSFB barely exists. Although there are a range of preventative measures these require scientific validation; critically, resistant/tolerant OSR cultivars are not yet available. Existing monitoring methods are time consuming and there are no commercial models to enable decision support based on predictions migration timing or population size. Available thresholds are not based on physiological tolerances of the plant making it hard to adapt them to changing market prices for the crop and costs of control. Non-synthetic alternatives tested and registered for use against CSFB are lacking, making resistance management impossible. CSFB control is therefore dependent upon conservation biocontrol. Natural enemies of CSFB are present, but quantification of their effects is needed and habitat management strategies to exploit their potential. Although some EU countries have local initiatives to reduce insecticide use and encourage use of ‘greener’ alternatives, there is no formal process for ranking these and little information available to help farmers make choices. We summarise the main knowledge gaps and future research needed to improve measures for CSFB control and to facilitate development of a full IPM strategy for this pest -and sustainable oilseeds production

    Debate for Civic Learning

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    Quantifying the impact of Psylliodes chrysocephala injury on the productivity of oilseed rape

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    BACKGROUND: Current European Union and United Kingdom legislation prohibits the use of neonicotinoid insecticidal seedtreatments in oilseed rape (OSR,Brassica napus). This ban, and the reduction in efficacy of pyrethroid insecticide sprays dueto resistance, has exacerbated pest pressure from the cabbage stemflea beetle (Psylliodes chrysocephala) in winter OSR. Wequantified the direct impact of P. chrysocephalainjury on the productivity of OSR. Leaf area was removed from young plantsto simulate differing intensities of adult feeding injury alone or in combination with varying larval infestation levels. RESULTS: OSR can compensate for up to 90% leaf area loss at early growth stages, with no meaningful effect on yield. Significant impacts were observed with high infestations of more thanfive larvae per plant; plants were shorter, produced fewerflowers and pods, with fewer seeds per pod which had lower oil content and higher glucosinolate content. Such effects werenot recorded whenfive larvae or fewer were present. CONCLUSION: These data confirm the yield-limiting potential of the larval stages ofP. chrysocephalabut suggest that the current action thresholds which trigger insecticide application for both adult and larval stages (25% leaf area loss andfive larvae/plant, respectively) are potentially too low as they are below the physiological injury level where plants can fully compensatefor damage. Further research infield conditions is needed to define physiological thresholds more accurately as disparity mayresult in insecticide applications that are unnecessary to protect yield and may in turn exacerbate the development and spread of insecticide resistance in P. chrysocephala

    Whisker/Cone growth on the thermal control surfaces experiment no. S0069

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    An unusual surface 'growth' was found during scanning electron microscope (SEM) investigations of the Thermal Control Surface Experiment (TCSE) S0069 front thermal cover. This 'growth' is similar to the cone type whisker growth phenomena as studied by G. K. Wehner beginning in the 1960's. Extensive analysis has identified the most probable composition of the whiskers to be a silicate type glass. Sources of the growth material are outgassing products from the experiment and orbital atomic oxygen, which occurs naturally at the orbital altitudes of the LDEF mission in the form of neutral atomic oxygen. The highly ordered symmetry and directionality of the whiskers are attributed to the long term (5.8 year) stable flight orientation of the LDEF
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