4,182 research outputs found

    Studies on the Radioactive Dating of the Lunar Surface Final Report

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    Remotely controlled rare gas analyzer with chemical reaction as energy source considered for radioactive dating of lunar surfac

    The genus Hebeloma in the alpine belt of the Carpathians including two new species

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    Between 2002 and 2012 regular visits to the Carpathians were made and a number of Hebeloma spp. were collected from the alpine area. In total 44 collections were made that represent 11 species, two of which, Hebeloma grandisporum and H oreophilum, are described here as new. Of the 11 species, four (H alpinum, H marginatulum and the two species described as new) are known only from alpine or Arctic habitats. Hebeloma dunense and H mesophaeum are commonly found in, but not restricted to, alpine habitats. The other five species (H aanenii, H laterinum, H naviculosparum, H vaccinum, H velutipes) are usually found in lowland or boreal habitats. Hebeloma naviculosporum is reported for the first time from the alpine zone and H alpinum for the first time as growing with Helianthemum. All but two species (H alpinum, H marginatulum) are reported for the first time from the Carpathian alpine zone. In this paper we discuss the habitat, the 11 recorded species and give detailed descriptions of the two new species, both morphologically and molecularly. A key for Hebeloma species from sect. Hebeloma occurring in Arctic-alpine habitats is provided

    K-Motives and Koszul Duality

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    We construct an ungraded version of Beilinson-Ginzburg-Soergel's Koszul duality for Langlands dual flag varieties, inspired by Beilinson's construction of rational motivic cohomology in terms of KK-theory. For this, we introduce and study categories DKS(X)\operatorname{DK}_{\mathcal{S}}(X) of S\mathcal{S}-constructible KK-motivic sheaves on varieties XX with an affine stratification S\mathcal{S}. We show that there is a natural and geometric functor, called Beilinson realisation, from S\mathcal{S}-constructible mixed sheaves DSmix(X)\operatorname{D}^{mix}_{\mathcal{S}}(X) to DKS(X)\operatorname{DK}_{\mathcal{S}}(X). We then show that Koszul duality intertwines the Betti realisation and Beilinson realisation functors and descends to an equivalence of constructible sheaves and constructible KK-motivic sheaves on Langlands dual flag varieties

    Springer Motives

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    We show that the motive of a Springer fiber is pure Tate. We then consider a category of equivariant Springer motives on the nilpotent cone and construct an equivalence to the derived category of graded modules over the graded affine Hecke algebra

    On-orbit cryogenic fluid transfer

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    A number of future NASA and DOD missions have been identified that will require, or could benefit from resupply of cryogenic liquids in orbit. The most promising approach for accomplishing cryogenic fluid transfer in the weightlessness environment of space is to use the thermodynamic filling technique. This approach involves initially reducing the receiver tank temperature by using several charge hold vent cycles followed by filling the tank without venting. Martin Marietta Denver Aerospace, under contract to the NASA Lewis Research Center, is currently developing analytical models to describe the on orbit cryogenic fluid transfer process. A detailed design of a shuttle attached experimental facility, which will provide the data necessary to verify the analytical models, is also being performed

    Bayesian Spam Detection

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    Spammers always find new ways to get spammy content to the public. Very commonly this is accomplished by using email, social media, or advertisements. According to a 2011 report by the Messaging Anti-Abuse Working Group roughly 90% of all emails in the United States are spam. This is why we will be taking a more detailed look at email spam. Spam filters have been getting better at detecting spam and removing it, but no method is able to block 100% of it. Because of this, many different methods of text classification have been developed, including a group of classifiers that use a Bayesian approach. The Bayesian approach to spam filtering was one of the earliest methods used to filter spam, and it remains relevant to this day. In this paper we will analyze 2 specific optimizations of Naive Bayes text classification and spam filtering, looking at the differences between them and how they have been used in practice. This paper will show that Bayesian filtering can be simply implemented for a reasonably accurate text classifier and that it can be modified to make a significant impact on the accuracy of the filter. A variety of applications will be explored as well

    Cryogenic fluid management experiment

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    The cryogenic fluid management experiment (CFME), designed to characterize subcritical liquid hydrogen storage and expulsion in the low-q space environment, is discussed. The experiment utilizes a fine mesh screen fluid management device to accomplish gas-free liquid expulsion and a thermodynamic vent system to intercept heat leak and control tank pressure. The experiment design evolved from a single flight prototype to provision for a multimission (up to 7) capability. A detailed design of the CFME, a dynamic test article, and dedicated ground support equipment were generated. All materials and parts were identified, and components were selected and specifications prepared. Long lead titanium pressurant spheres and the flight tape recorder and ground reproduce unit were procured. Experiment integration with the shuttle orbiter, Spacelab, and KSC ground operations was coordinated with the appropriate NASA centers, and experiment interfaces were defined. Phase 1 ground and flight safety reviews were conducted. Costs were estimated for fabrication and assembly of the CFME, which will become the storage and supply tank for a cryogenic fluid management facility to investigate fluid management in space

    Behavior of fluids in a weightless environment

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    Fluid behavior in a low-g environment is controlled primarily by surface tension forces. Certain fluid and system characteristics determine the magnitude of these forces for both a free liquid surface and liquid in contact with a solid. These characteristics, including surface tension, wettability or contact angle, system geometry, and the relationships governing their interaction, are discussed. Various aspects of fluid behavior in a low-g environment are then presented. This includes the formation of static interface shapes, oscillation and rotation of drops, coalescence, the formation of foams, tendency for cavitation, and diffusion in liquids which were observed during the Skylab fluid mechanics science demonstrations. Liquid reorientation and capillary pumping to establish equilibrium configurations for various system geometries, observed during various free-fall (drop-tower) low-g tests, are also presented. Several passive low-g fluid storage and transfer systems are discussed. These systems use surface tension forces to control the liquid/vapor interface and provide gas-free liquid transfer and liquid-free vapor venting

    Research in the development of an improved multiplier phototube

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    Performance and response characteristics of smoothing, image intensifier dissector for low light level astronomy and optical detectio

    Structure- and context-based analysis of the GxGYxYP family reveals a new putative class of glycoside hydrolase.

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    BackgroundGut microbiome metagenomics has revealed many protein families and domains found largely or exclusively in that environment. Proteins containing the GxGYxYP domain are over-represented in the gut microbiota, and are found in Polysaccharide Utilization Loci in the gut symbiont Bacteroides thetaiotaomicron, suggesting their involvement in polysaccharide metabolism, but little else is known of the function of this domain.ResultsGenomic context and domain architecture analyses support a role for the GxGYxYP domain in carbohydrate metabolism. Sparse occurrences in eukaryotes are the result of lateral gene transfer. The structure of the GxGYxYP domain-containing protein encoded by the BT2193 locus reveals two structural domains, the first composed of three divergent repeats with no recognisable homology to previously solved structures, the second a more familiar seven-stranded β/α barrel. Structure-based analyses including conservation mapping localise a presumed functional site to a cleft between the two domains of BT2193. Matching to a catalytic site template from a GH9 cellulase and other analyses point to a putative catalytic triad composed of Glu272, Asp331 and Asp333.ConclusionsWe suggest that GxGYxYP-containing proteins constitute a novel glycoside hydrolase family of as yet unknown specificity
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