236 research outputs found

    Requirements and Sizing Investigation for Constellation Space Suit Portable Life Support System Trace Contaminant Control

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    The Trace Contaminant Control System (TCCS), located within the ventilation loop of the Constellation Space Suit Portable Life Support System (PLSS), is responsible for removing hazardous trace contaminants from the space suit ventilation flow. This paper summarizes the results of a trade study that evaluated if trace contaminant control could be accomplished without a TCCS, relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Trace contaminant generation rates were revisited to verify that values reflect the latest designs for Constellation Space Suit System (CSSS) pressure garment materials and PLSS hardware. Additionally, TCCS sizing calculations were performed and a literature survey was conducted to review the latest developments in trace contaminant technologies

    Low Mass Stars and Substellar Objects in the NGC 1333 Molecular Cloud

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    We present the results of near-infrared imaging and low-resolution near- infrared spectroscopy of low mass objects in the NGC 1333 molecular cloud. A JHK survey of an 11.4' x 11.7' area of the northern cluster was conducted to a sensitivity of K < 16 mag. Using near-infrared magnitudes and colors from this and previously published surveys, twenty-five brown dwarf candidates were selected toward the high extinction cloud core. Spectra in the K band were obtained and comparisons of the depths of water vapor absorption bands in our candidate objects with a grid of dwarf,subgiant, and giant standards were made to derive spectral types. These data were then used to derive effective temperatures and stellar luminosities which, when combined with theoretical tracks and isochrones for pre-main sequence objects, resulted in estimates for their masses and ages. The models suggest a median age for the sample of < 1 Myr with substellar masses for at least 9 of the candidates including the x-ray flare source ASR 24. Surface gravities have been estimated for the brown dwarf candidates and, for a given spectral type,found to resemble more closely dwarfs than giants. Using the near-infrared imaging data and age estimates from the spectroscopic sample, an extinction-limited sample in the northern cluster was defined. Consistent with recent studies of other young clusters, this sample exhibits an accretion disk frequency of 0.75 +-0.20 and a mass spectrum slope across the hydrogen-burning limit of alpha < 1.6 where dN/dM ~ M^-(alpha).Comment: 22 postscript pages, 12 postscript figures, and 3 postscript tables. Accepted for publication in the Astronomical Journal (February, 2004

    Requirements and Sizing Investigation for the Constellation Space Suit Portable Life Support System Trace Contaminant Control

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    This presentation summarized the results of a trade study that evaluated whether trace contaminant control within the Constellation Spacesuit PLSS could be achieved without a Trace Contaminant Control System (TCCS) by relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Mallory Jennings and Dr. Glenn Waguespack studied trace contaminant generation rates to verify that values reflected the latest designs for Constellation spacesuit system pressure garment materials and PLSS hardware. They also calculated TCCS sizing and conducted a literature survey to review the latest developments in trace contaminant technologies

    The Thermal Infrared Sensor on the Landsat Data Continuity Mission

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    The Landsat Data Continuity Mission (LDCM), a joint NASA and USGS mission, is scheduled for launch in December, 2012. The LDCM instrument payload will consist of the Operational Land Imager (OLI), provided by Ball Aerospace and Technology Corporation (BATC} under contract to NASA and the Thermal Infrared Sensor (TIRS), provided by NASA's Goddard Space Flight Center (GSFC). This paper outlines the design of the TIRS instrument and gives an example of its application to monitoring water consumption by measuring evapotranspiration

    The qualification of an enrichment biomarker for clinical trials targeting early stages of Parkinson’s disease

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    As therapeutic trials target early stages of Parkinson’s disease (PD), appropriate patient selection based purely on clinical criteria poses significant challenges. Members of the Critical Path for Parkinson’s Consortium formally submitted documentation to the European Medicines Agency (EMA) supporting the use of Dopamine Transporter (DAT) neuroimaging in early PD. Regulatory documents included a comprehensive literature review, a proposed analysis plan of both observational and clinical trial data, and an assessment of biomarker reproducibility and reliability. The research plan included longitudinal analysis of the Parkinson Research Examination of CEP-1347 Trial (PRECEPT) and the Parkinson’s Progression Markers Initiative (PPMI) study to estimate the degree of enrichment achieved and impact on future trials in subjects with early motor PD. The presence of reduced striatal DAT binding based on visual reads of single photon emission tomography (SPECT) scans in early motor PD subjects was an independent predictor of faster decline in UPDRS Parts II and III as compared to subjects with scans without evidence of dopaminergic deficit (SWEDD) over 24 months. The EMA issued in 2018 a full Qualification Opinion for the use of DAT as an enrichment biomarker in PD trials targeting subjects with early motor symptoms. Exclusion of SWEDD subjects in future clinical trials targeting early motor PD subjects aims to enrich clinical trial populations with idiopathic PD patients, improve statistical power, and exclude subjects who are unlikely to progress clinically from being exposed to novel test therapeutics

    Changing Politics: Towards a New Democracy

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    In October 2014 the PSA joint-funded a Consultation event ‘Changing Politics – Towards a New Democracy’ with St. George’s House. The Chair of the PSA, Professor Matthew Flinders, chaired the event which brought together participants from a range of fields (including academics, think tankers and practitioners in several policy areas). Today, St. George’s House has published a report which highlights the main themes emerging from the discussion as well as some conclusions and recommendations. It identifies several areas where changes are urgently needed to reinvigorate democracy. The report concludes that to fully succeed in addressing the growth of political apathy and disengagement, parties and leaders must forget their differences and join citizens, academics, charities and others to address this problem with all available energy and resources

    Aptamer-based multiplexed proteomic technology for biomarker discovery

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    Interrogation of the human proteome in a highly multiplexed and efficient manner remains a coveted and challenging goal in biology. We present a new aptamer-based proteomic technology for biomarker discovery capable of simultaneously measuring thousands of proteins from small sample volumes (15 [mu]L of serum or plasma). Our current assay allows us to measure ~800 proteins with very low limits of detection (1 pM average), 7 logs of overall dynamic range, and 5% average coefficient of variation. This technology is enabled by a new generation of aptamers that contain chemically modified nucleotides, which greatly expand the physicochemical diversity of the large randomized nucleic acid libraries from which the aptamers are selected. Proteins in complex matrices such as plasma are measured with a process that transforms a signature of protein concentrations into a corresponding DNA aptamer concentration signature, which is then quantified with a DNA microarray. In essence, our assay takes advantage of the dual nature of aptamers as both folded binding entities with defined shapes and unique sequences recognizable by specific hybridization probes. To demonstrate the utility of our proteomics biomarker discovery technology, we applied it to a clinical study of chronic kidney disease (CKD). We identified two well known CKD biomarkers as well as an additional 58 potential CKD biomarkers. These results demonstrate the potential utility of our technology to discover unique protein signatures characteristic of various disease states. More generally, we describe a versatile and powerful tool that allows large-scale comparison of proteome profiles among discrete populations. This unbiased and highly multiplexed search engine will enable the discovery of novel biomarkers in a manner that is unencumbered by our incomplete knowledge of biology, thereby helping to advance the next generation of evidence-based medicine

    Recombinant plants provide a new approach to the production of bacterial polysaccharide for vaccines

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    Bacterial polysaccharides have numerous clinical or industrial uses. Recombinant plants could offer the possibility of producing bacterial polysaccharides on a large scale and free of contaminating bacterial toxins and antigens. We investigated the feasibility of this proposal by cloning and expressing the gene for the type 3 synthase (cps3S) of Streptococcus pneumoniae in Nicotinia tabacum, using the pCambia2301 vector and Agrobacterium tumefaciens-mediated gene transfer. In planta the recombinant synthase polymerised plant-derived UDP-glucose and UDP-glucuronic acid to form type 3 polysaccharide. Expression of the cps3S gene was detected by RT-PCR and production of the pneumococcal polysaccharide was detected in tobacco leaf extracts by double immunodiffusion, Western blotting and high-voltage paper electrophoresis. Because it is used a component of anti-pneumococcal vaccines, the immunogenicity of the plant-derived type 3 polysaccharide was tested. Mice immunised with extracts from recombinant plants were protected from challenge with a lethal dose of pneumococci in a model of pneumonia and the immunised mice had significantly elevated levels of serum anti-pneumococcal polysaccharide antibodies. This study provides the proof of the principle that bacterial polysaccharide can be successfully synthesised in plants and that these recombinant polysaccharides could be used as vaccines to protect against life-threatening infections

    Who will make the 'best' use of Africa's land? Lessons from Zimbabwe

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    Conflict over African land – between small holders and large industrial farmers and between domestic farmers and global agribusinesses – raises key questions about who will make the best use of African land and which farmers do most to decrease poverty and produce more food, industrial inputs, and exports. Zimbabwe has already gone through two major changes in land occupation, and thus provides an important test of what is the 'best' use of the land. Three measures of 'best' use have been cited in Zimbabwe: reward for military victory, poverty reduction, and agricultural production. Initial evidence indicates that commercial small holder production is a better use of the land than larger, more mechanised farming
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