4,219 research outputs found

    Numerical aerodynamic simulation program long haul communications prototype

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    This document is a report of the Numerical Aerodynamic Simulation (NAS) Long Haul Communications Prototype (LHCP). It describes the accomplishments of the LHCP group, presents the results from all LHCP experiments and testing activities, makes recommendations for present and future LHCP activities, and evaluates the remote workstation accesses from Langley Research Center, Lewis Research Center, and Colorado State University to Ames Research Center. The report is the final effort of the Long Haul (Wideband) Communications Prototype Plan (PT-1133-02-N00), 3 October 1985, which defined the requirements for the development, test, and operation of the LHCP network and was the plan used to evaluate the remote user bandwidth requirements for the Numerical Aerodynamic Simulation Processing System Network

    Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O

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    Although the microscopic origin of the superconductivity in high Tc copper oxides remains the subject of active inquiry, several of their electronic characteristics are well established as universal to all the known materials, forming the experimental foundation that all theories must address. The most fundamental of those characteristics is the dependence of the superconducting transition temperature on the degree of electronic band filling. Since the discovery of cuprate superconductivity in 1986 (1), the search for other families of superconductors that might help shed light on the superconducting mechanism of the cuprates has been of great interest. The recent report of superconductivity near 4K in the triangular lattice, layered sodium cobalt oxyhydrate, Na0.35CoO2.1.3H2O, is the best indication that superconductors related to the cuprates may be found (2). Here we show that the superconducting transition temperature of this compound displays the same kind of band-filling behavior that is observed in the cuprates. Specifically, that the optimal superconducting Tc occurs in a narrow range of band filling, and decreases for both underdoped and overdoped materials, in dramatic analogy to the phase diagram of the cuprate superconductors. Our results suggest that characterization of the detailed electronic and magnetic behavior of these new materials may help establish which of the many special characteristics of the cuprates is fundamental to their high Tc superconductivity.Comment: revised, publication information adde

    Experimental annotation of the human pathogen Histoplasma capsulatum transcribed regions using high-resolution tiling arrays

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    <p>Abstract</p> <p>Background</p> <p>The fungal pathogen <it>Histoplasma capsulatum </it>is thought to be the most common cause of fungal respiratory infections in immunocompetent humans, yet little is known about its biology. Here we provide the first genome-wide studies to experimentally validate its genome annotation. A functional interrogation of the <it>Histoplasma </it>genome provides critical support for continued investigation into the biology and pathogenesis of <it>H. capsulatum </it>and related fungi.</p> <p>Results</p> <p>We employed a three-pronged approach to provide a functional annotation for the <it>H. capsulatum </it>G217B strain. First, we probed high-density tiling arrays with labeled cDNAs from cells grown under diverse conditions. These data defined 6,172 transcriptionally active regions (TARs), providing validation of 6,008 gene predictions. Interestingly, 22% of these predictions showed evidence of anti-sense transcription. Additionally, we detected transcription of 264 novel genes not present in the original gene predictions. To further enrich our analysis, we incorporated expression data from whole-genome oligonucleotide microarrays. These expression data included profiling under growth conditions that were not represented in the tiling experiment, and validated an additional 2,249 gene predictions. Finally, we compared the G217B gene predictions to other available fungal genomes, and observed that an additional 254 gene predictions had an ortholog in a different fungal species, suggesting that they represent genuine coding sequences.</p> <p>Conclusions</p> <p>These analyses yielded a high confidence set of validated gene predictions for <it>H. capsulatum</it>. The transcript sets resulting from this study are a valuable resource for further experimental characterization of this ubiquitous fungal pathogen. The data is available for interactive exploration at <url>http://histo.ucsf.edu</url>.</p

    Interface relaxation in electrophoretic deposition of polymer chains: Effects of segmental dynamics, molecular weight, and field

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    Using different segmental dynamics and relaxation, characteristics of the interface growth is examined in an electrophoretic deposition of polymer chains on a three (2+1) dimensional discrete lattice with a Monte Carlo simulation. Incorporation of faster modes such as crankshaft and reptation movements along with the relatively slow kink-jump dynamics seems crucial in relaxing the interface width. As the continuously released polymer chains are driven (via segmental movements) and deposited, the interface width WW grows with the number of time steps tt, Wtβ,W \propto t^{\beta}, (β0.4\beta \sim 0.4--0.8)0.8), which is followed by its saturation to a steady-state value WsW_s. Stopping the release of additional chains after saturation while continuing the segmental movements relaxes the saturated width to an equilibrium value (WsWrW_s \to W_r). Scaling of the relaxed interface width WrW_r with the driving field EE, WrE1/2W_r \propto E^{-1/2} remains similar to that of the steady-state WsW_s width. In contrast to monotonic increase of the steady-state width WsW_s, the relaxed interface width WrW_r is found to decay (possibly as a stretched exponential) with the molecular weight.Comment: 5 pages, 7 figure

    Novel phase diagram of superconductor NaxCoO2-yH2O in a 75 % relative humidity

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    We succeeded in synthesizing the powder samples of bilayer-hydrate sodium cobalt oxide superconductors NaxCoO2-yH2O with Tc = 0 ~ 4.6 K by systematically changing the keeping duration in a 75 % relative humidity atmosphere after intercalation of water molecules. From the magnetic measurements, we found that the one-day duration sample does not show any superconductivity down to 1.8 K, and that the samples kept for 2 ~ 7 days show superconductivity, in which Tc increases up to 4.6 K with increasing the duration. Tc and the superconducting volume fraction are almost invariant between 7 days and 1month duration. The 59Co NQR spectra indicate a systematic change in the local charge distribution on the CoO2 plane with change in duration.Comment: 4 pages, 5 figures, submitted to Journal of the Physical Society of Japa

    Indoor Air Quality and Office Property Value

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    Urbanization and technological advancement have resulted in many urbanites working in window-sealed high-rise office buildings. Many researchers have found that indoor air quality (IAQ) affects tenantlandlord relationships, workers’ health and productivity, and building elements and systems. This may imply that IAQ could affect, positively or negatively, the value of buildings. This paper examines the impact of IAQ on the value of office buildings in Singapore. The results show that the return on investment in IAQ could be substantial (78.56%) while property values could increase by 1.28% to 3.85%. The findings could be of interest and usefulness to valuers and investors in office properties in Singapore and thus, help to promote sustainability in office property developments

    Development of a Friction Rig and Experimental Results

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    The development of a friction rig, which is integrated into a milling machine for testing the frictional characteristics of various types of materials and specimen shapes are described. This is followed by the experimental technique used to measure the friction coefficient for different experimental conditions. The results obtained indicate the frictional coefficient obtained changes with the specimen type, contact area and lubrication condition. The results obtained are also compared to available published results. The discussions and conclusions related to the development and experimental results are finally presented
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