22,163 research outputs found

    On the evolution of advanced propulsion systems for spacecraft

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    Use of earth-storable propellants in unmanned spacecraft propulsion systems for flights to near planets and moo

    Allograft and Xenograft Acceptance under FK‐506 and Other Immunosuppressant Treatment

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    We will focus on two issues, both involving, but not confined to FK-506: first, the meaning of the graft acceptance, which is, after all, the objective of immunosuppression for the transplant surgeon; and second, how to take the next great step of xenotransplantation

    MCMC Exploration of Supermassive Black Hole Binary Inspirals

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    The Laser Interferometer Space Antenna will be able to detect the inspiral and merger of Super Massive Black Hole Binaries (SMBHBs) anywhere in the Universe. Standard matched filtering techniques can be used to detect and characterize these systems. Markov Chain Monte Carlo (MCMC) methods are ideally suited to this and other LISA data analysis problems as they are able to efficiently handle models with large dimensions. Here we compare the posterior parameter distributions derived by an MCMC algorithm with the distributions predicted by the Fisher information matrix. We find excellent agreement for the extrinsic parameters, while the Fisher matrix slightly overestimates errors in the intrinsic parameters.Comment: Submitted to CQG as a GWDAW-10 Conference Proceedings, 9 pages, 5 figures, Published Versio

    Insulation bonding test system

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    A method and a system for testing the bonding of foam insulation attached to metal is described. The system involves the use of an impacter which has a calibrated load cell mounted on a plunger and a hammer head mounted on the end of the plunger. When the impacter strikes the insulation at a point to be tested, the load cell measures the force of the impact and the precise time interval during which the hammer head is in contact with the insulation. This information is transmitted as an electrical signal to a load cell amplifier where the signal is conditioned and then transmitted to a fast Fourier transform (FFT) analyzer. The FFT analyzer produces energy spectral density curves which are displayed on a video screen. The termination frequency of the energy spectral density curve may be compared with a predetermined empirical scale to determine whether a igh quality bond, good bond, or debond is present at the point of impact

    Characterisation of bulk water samples from copper pipes undergoing microbially influenced corrosion by diagnostic metabolomic profiling

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    This paper presents the application of metabolomic techniques to determine the presence of microbial influenced corrosion (MIC). In a previous study, the extracellular metabolites expressed from pipe biofilm was identified by analysing the passing water. This investigation extends this work by successfully applying a chemometric statistical analysis to the extracellular metabolomic profile of a number of water samples to identify critical metabolomic biomarkers. The chemometric analysis was able to differentiate samples due to a reduction of carboxylic acids in samples exposed to bacteria believed to cause MIC

    The art of HIV elimination: past and present science

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    Introduction: Remarkable strides have been made in controlling the HIV epidemic, although not enough to achieve epidemic control. More recently, interest in biomedical HIV control approaches has increased, but substantial challenges with the HIV cascade of care hinder successful implementation. We summarise all available HIV prevention methods and make recommendations on how to address current challenges. Discussion: In the early days of the epidemic, behavioural approaches to control the HIV dominated, and the few available evidence-based interventions demonstrated to reduce HIV transmission were applied independently from one another. More recently, it has become clear that combination prevention strategies targeted to high transmission geographies and people at most risk of infections are required to achieve epidemic control. Biomedical strategies such as male medical circumcision and antiretroviral therapy for treatment in HIV-positive individuals and as preexposure prophylaxis in HIV-negative individuals provide immense promise for the future of HIV control. In resourcerich settings, the threat of HIV treatment optimism resulting in increased sexual risk taking has been observed and there are concerns that as ART roll-out matures in resource-poor settings and the benefits of ART become clearly visible, behavioural disinhibition may also become a challenge in those settings. Unfortunately, an efficacious vaccine, a strategy which could potentially halt the HIV epidemic, remains elusive. Conclusion: Combination HIV prevention offers a logical approach to HIV control, although what and how the available options should be combined is contextual. Therefore, knowledge of the local or national drivers of HIV infection is paramount. Problems with the HIV care continuum remain of concern, hindering progress towards the UNAIDS target of 90-90-90 by 2020. Research is needed on combination interventions that address all the steps of the cascade as the steps are not independent of each other. Until these issues are addressed, HIV elimination may remain an unattainable goal

    Remote Marine Aerosol: A Characterization of Physical, Chemical and Optical Properties and their Relation to Radiative Transfer in the Troposphere

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    Our research effort is focused on improving our understanding of aerosol properties needed for optical models for remote marine regions. This includes in-situ and vertical column optical closure and involves a redundancy of approaches to measure and model optical properties that must be self consistent. The model is based upon measured in-situ aerosol properties and will be tested and constrained by the vertically measured spectral differential optical depth of the marine boundary layer, MBL. Both measured and modeled column optical properties for the boundary layer, when added to the free-troposphere and stratospheric optical depth, will be used to establish spectral optical depth over the entire atmospheric column for comparison to and validation of satellite derived radiances (AVHRR)

    Evaluation and export of Pseudacteon decapitating flies (Phoridae:Diptera) collected in the Jaguariuna area for fire ant biocontrol in the USA.

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    Fire ant decapitating flies were studied in and around the Embrapa-National Research Center for Environmental Monitoring and Impact Assessment, in Jaguariuna, State of Sao Paulo, Brazil. The objective was to evaluate and select several species for exporting to the United States as biocontrol agents. Eight species were collected during this study (January-June, 1996): Pseudacteon convexicauda, P. curvatus, P. litoralis, P. obtusus, P. pradei, P. solenopsidis, P. tricuspis and P. wasmanni. Seven species (all except P. convexicauda) were reared from eggs to adults. All seven species had the unusual habit of pupating inside the head capsule of their host. No suitable morphological characters were found to discriminate pupae of the different species. Pupae of different sexes were also indistinguishable except that females consistently emerged from larger hosts than males. The males of P. tricuspis readily mated with females while they were ovipositing in fire ant workers, but it was not possible to determine when and were other species of decapitating flies mated. Consequently, it was only possible to develop techniques for rearing P. tricuspis. Two species (P.tricuspis and p. litoralis) were sufficiently abundant to be exported to the USDA-ARS from Brazilian Quarantine Laboratory for specificity testing. After a period in USDA quarantine facilities both species received permission to be released and tested under field conditions in the USA

    VELO Module Production - Cable Testing

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    This note describes in detail the procedures used in the reception, handling, testing and storage of HT and LT cables for the LHCb VELO detector modules
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