1,206 research outputs found

    MSFC Skylab attitude and pointing control system mission evaluation

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    The results of detailed performance analyses of the attitude and pointing control system in-orbit hardware and software on Skylab are reported. Performance is compared with requirements, test results, and prelaunch predictions. A brief history of the altitude and pointing control system evolution leading to the launch configuration is presented. The report states that the attitude and pointing system satisfied all requirements

    Stabilization and control of the Apollo Telescope Mount

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    Apollo Telescope Mount stabilization and control, with control moment gyro and experiment pointing control subsystem

    Assessment of disk MHD generators for a base load powerplant

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    Results from a study of the disk MHD generator are presented. Both open and closed cycle disk systems were investigated. Costing of the open cycle disk components (nozzle, channel, diffuser, radiant boiler, magnet and power management) was done. However, no detailed costing was done for the closed cycle systems. Preliminary plant design for the open cycle systems was also completed. Based on the system study results, an economic assessment of the open cycle systems is presented. Costs of the open cycle disk conponents are less than comparable linear generator components. Also, costs of electricity for the open cycle disk systems are competitive with comparable linear systems. Advantages of the disk design simplicity are considered. Improvements in the channel availability or a reduction in the channel lifetime requirement are possible as a result of the disk design

    Effect of Temperature Gradient on Thick Film Selective Emitter Emittance

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    A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance

    Studies on Some Immunological Aspects of Australian Infectious Bronchitis Viruses

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    Prior to 1962, infectious bronchitis (IB) virus had not been identified in Australia. Certainly the disease syndrome caused by IB virus, as seen in Europe and America (Beister and Schwarte, 1959) had not been described in Australia (Gilchrist, 1962, Hungerford, 1962), although reports by Hart (1946), Newton and Simmons (1963) and Gilchrist (1962), all describe syndromes which had some aspects reminiscent of IB infections. One of the prominent poultry diseases at that time had been characterised by a breakdown in kidney function producing a 'uraemia' or nephritis (Hungerford, 1969). This syndrome had been seen since 1948 and was thought possibly to be caused by some nutritional factor (Beilharz and McDonald, 1960). In 1962, Cumming isolated a virus from cases of nephritis and suggested the virus to be IB. This was confirmed by Cumming (1963, 1964), Gilchrist (1963), and Gilchrist and Sinkovic (1964). Supporting serological evidence for the identity of the virus being IB was given by cross neutralisation studies with American IB viruses (Winterfield et al., 1964a), British IB viruses (Berry and Stokes, 1968) and some German IB viruses (von Bulow, 1967). Berry and Stokes (1968) also confirmed the Australian IB virus as a corona-virus by electron microscopy. ... The main approach to the disease problem associated with IB virus infections in the past has been based on the serum neutralisation relationships of the viruses involved and the ability of vaccine viruses to induce these antibodies in birds. The approach to the problem used in this thesis has been based on the ability of virus infections to induce resistance in birds to the affects of virulent IB virus challenge and to evaluate the relationship of this resistance to antibody production. This approach has been aided by, the characteristic of Australian IB viruses to cause death with nephritis under controlled experimental conditions

    On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example

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    The study of exoplanetary atmospheres relies on detecting minute changes in the transit depth at different wavelengths. To date, a number of ground- and space-based instruments have been used to obtain transmission spectra of exoplanets in different spectral bands. One common practice is to combine observations from different instruments in order to achieve a broader wavelength coverage. We present here two inconsistent observations of WASP-96 b, one by the Hubble Space Telescope (HST) and the other by the Very Large Telescope (VLT). We present two key findings in our investigation: (1) a strong water signature is detected via the HST WFC3 observations and (2) a notable offset in transit depth (>1100 ppm) can be seen when the ground-based and space-based observations are combined. The discrepancy raises the question of whether observations from different instruments could indeed be combined. We attempt to align the observations by including an additional parameter in our retrieval studies but are unable to definitively ascertain that the aligned observations are indeed compatible. The case of WASP-96 b signals that compatibility of instruments should not be assumed. While wavelength overlaps between instruments can help, it should be noted that combining data sets remains risky business. The difficulty of combining observations also strengthens the need for next-generation instruments that possess broader spectral coverage

    Genomes2Drugs: Identifies Target Proteins and Lead Drugs from Proteome Data

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    Background: Genome sequencing and bioinformatics have provided the full hypothetical proteome of many pathogenic organisms. Advances in microarray and mass spectrometry have also yielded large output datasets of possible target proteins/genes. However, the challenge remains to identify new targets for drug discovery from this wealth of information. Further analysis includes bioinformatics and/or molecular biology tools to validate the findings. This is time consuming and expensive, and could fail to yield novel drugs if protein purification and crystallography is impossible. To pre-empt this, a researcher may want to rapidly filter the output datasets for proteins that show good homology to proteins that have already been structurally characterised or proteins that are already targets for known drugs. Critically, those researchers developing novel antibiotics need to select out the proteins that show close homology to any human proteins, as future inhibitors are likely to cross-react with the host protein, causing off-target toxicity effects later in clinical trials. Methodology/Principal Findings: To solve many of these issues, we have developed a free online resource called Genomes2Drugs which ranks sequences to identify proteins that are (i) homologous to previously crystallized proteins or (ii) targets of known drugs, but are (iii) not homologous to human proteins. When tested using the Plasmodium falciparum malarial genome the program correctly enriched the ranked list of proteins with known drug target proteins. Conclusions/Significance: Genomes2Drugs rapidly identifies proteins that are likely to succeed in drug discovery pipelines

    Evaluating the cost-effectiveness of insulin detemir versus neutral protamine Hagedorn insulin in patients with type 1 or type 2 diabetes in the UK using a short-term modeling approach

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    Background: To estimate the short-term cost-effectiveness of insulin detemir (IDet) versus neutral protamine Hagedorn (NPH) insulin based on the incidence of non-severe hypoglycemia and changes in body weight in subjects with type 1 diabetes (T1D) or type 2 diabetes (T2D) in the UK. Methods: A model was developed to evaluate cost-effectiveness based on non-severe hypoglycemia, body mass index, and pharmacy costs over 1 year. Published rates of non-severe hypoglycemia were employed in the T1D and T2D analyses, while reduced weight gain with IDet was modeled in the T2D analysis only. Effectiveness was calculated in terms of quality-adjusted life expectancy using published utility scores. Pharmacy costs were captured using published prices and defined daily doses. Costs were expressed in 2016 pounds sterling (GBP). Sensitivity analyses were performed (including probabilistic sensitivity analysis). Results: In T1D, IDet was associated with fewer non-severe hypoglycemic events than NPH insulin (126.7 versus 150.8 events per person-year), leading to an improvement of 0.099 quality-adjusted life years (QALYs). Costs with IDet were GBP 60 higher, yielding an incremental cost-effectiveness ratio (ICER) of GBP 610 per QALY gained. In T2D, mean non-severe hypoglycemic event rates and body weight were lower with IDet than NPH insulin, leading to a total incremental utility of 0.120, accompanied by an annual cost increase of GBP 171, yielding an ICER of GBP 1,422 per QALY gained for IDet versus NPH insulin. Conclusion: Short-term health economic evaluation showed IDet to be a cost-effective alternative to NPH insulin in the UK due to lower rates of non-severe hypoglycemia (T1D and T2D) and reduced weight gain (T2D only)
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