250 research outputs found

    Resonant formation of Lambda(1405) by stopped-K- absorption in deuteron

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    To solve the current debate on the position of the quasi-bound K^-p state, namely, "Lambda(1405) or Lambda*(1420)", we propose to measure the T_{21} = T_{Sigma-pi \leftarrow Kbar-N} Sigma-pi invariant-mass spectrum in stopped-K- absorption in deuteron, since the spectrum, reflecting the soft and hard deuteron momentum distribution, is expected to have a narrow quasi-free component with an upper edge of M = 1430 MeV/c^2, followed by a significant "high-momentum" tail toward the lower mass region, where a resonant formation of Lambda(1405) of any mass and width in a wide range is revealed. We introduce a "deviation" spectrum as defined by DEV = OBS (observed or calculated) / QF (non-resonant quasi-free), in which the resonant component can be seen as an isolated peak free from the QF shape.Comment: 7 pages, 6 figure

    Groeten uit... Stellenbosch

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    In elke editie wordt er aandacht besteed aan studenten die een ti jd in het buitenland gestudeerd hebben of er studeren. Een populaire locati e is Stellenbosch in Zuid-Afrika. Zo ging Dieuwertje de Rover in het eerste semester van dit jaar ook deze kant op. In dit studieverslag gaat ze in op haar unieke ervaringen, maar vertelt ze ook over het harde Afrikaanse leven

    Process of ontology construction for the development of an intelligent system for the organization and retrieval of knowledge in biodiversity – SISBIO

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    This work describes the ontology construction process for the development of an Intelligent System for the Organization and Retrieval of Knowledge in Biodiversity – SISBIO. The system aims at the production of strategic information for the biofuel chain Two main methodologies are used for the construction of the ontologies: knowledge engineering and ontology engineering. The first one consists of extracting and organizing the biofuel specialists´ knowledge, and ontology engineering is used to represent the knowledge through indicative expressions and its relations, developing a semantic network of relationships.Applications in Artificial Intelligence - Ontologies and Intelligent WebRed de Universidades con Carreras en Informática (RedUNCI

    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

    Hydrocarbon Liquid Production via Catalytic Hydroprocessing of Phenolic Oils Fractionated from Fast Pyrolysis of Red Oak and Corn Stover

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    Phenolic oils were produced from fast pyrolysis of two different biomass feedstocks, red oak and corn stover, and evaluated in hydroprocessing tests for production of liquid hydrocarbon products. The phenolic oils were produced with a bio-oil fractionating process in combination with a simple water wash of the heavy ends from the fractionating process. Phenolic oils derived from the pyrolysis of red oak and corn stover were recovered with yields (wet biomass basis) of 28.7 and 14.9 wt %, respectively, and 54.3% and 60.0% on a carbon basis. Both precious metal catalysts and sulfided base metal catalyst were evaluated for hydrotreating the phenolic oils, as an extrapolation from whole bio-oil hydrotreatment. They were effective in removing heteroatoms with carbon yields as high as 81% (unadjusted for the 90% carbon balance). There was substantial heteroatom removal with residual O of only 0.4% to 5%, while N and S were reduced to less than 0.05%. Use of the precious metal catalysts resulted in more saturated products less completely hydrotreated compared to the sulfided base metal catalyst, which was operated at higher temperature. The liquid product was 42–52% gasoline range molecules and about 43% diesel range molecules. Particulate matter in the phenolic oils complicated operation of the reactors, causing plugging in the fixed-beds especially for the corn stover phenolic oil. This difficulty contrasts with the catalyst bed fouling and plugging, which is typically seen with hydrotreatment of whole bio-oil. This problem was substantially alleviated by filtering the phenolic oils before hydrotreating. More thorough washing of the phenolic oils during their preparation from the heavy ends of bio-oil or online filtration of pyrolysis vapors to remove particulate matter before condensation of the bio-oil fractions is recommended.Reprinted with permission from ACS Sustainable Chem. Eng., 2015, 3 (5), pp 892–902. Copyright 2015 American Chemical Society.</p

    Process of ontology construction for the development of an intelligent system for the organization and retrieval of knowledge in biodiversity – SISBIO

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    This work describes the ontology construction process for the development of an Intelligent System for the Organization and Retrieval of Knowledge in Biodiversity – SISBIO. The system aims at the production of strategic information for the biofuel chain Two main methodologies are used for the construction of the ontologies: knowledge engineering and ontology engineering. The first one consists of extracting and organizing the biofuel specialists´ knowledge, and ontology engineering is used to represent the knowledge through indicative expressions and its relations, developing a semantic network of relationships.Applications in Artificial Intelligence - Ontologies and Intelligent WebRed de Universidades con Carreras en Informática (RedUNCI

    Evolution of Broader Impacts

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    This work is supported by the National Science Foundation under grant number OIA-1810732 and MCB-1940655, the Kavli Foundation and the Burroughs Wellcome Fund. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the Kavli Foundation or Burroughs Wellcome Fund

    Overexpression of human kynurenine-3-monooxygenase protects against 3-hydroxykynurenine-mediated apoptosis through bidirectional non-linear feedback

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    Kynurenine 3-monooxygenase (KMO) is a critical regulator of inflammation. The preferred KMO substrate, kynurenine, is converted to 3-hydroxykynurenine (3HK), and this product exhibits cytotoxicity through mechanisms that culminate in apoptosis. Here, we report that overexpression of human KMO with orthotopic localisation to mitochondria creates a metabolic environment during which the cell exhibits increased tolerance for exogenous 3HK-mediated cellular injury. Using the selective KMO inhibitor Ro61-8048, we show that KMO enzyme function is essential for cellular protection. Pan-caspase inhibition with Z-VAD-FMK confirmed apoptosis as the mode of cell death. By defining expression of pathway components upstream and downstream of KMO, we observed alterations in other key kynurenine pathway components, particularly tryptophan-2,3-dioxygenase upregulation, through bidirectional nonlinear feedback. KMO overexpression also increased expression of inducible nitric oxide synthase (iNOS). These changes in gene expression are functionally relevant, because siRNA knockdown of the pathway components kynureninase and quinolinate phosphoribosyl transferase caused cells to revert to a state of susceptibility to 3HK-mediated apoptosis. In summary, KMO overexpression, and importantly KMO activity, have metabolic repercussions that fundamentally affect resistance to cell stress

    Implications For The Origin Of GRB 051103 From LIGO Observations

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    We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at the distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with > 99% confidence. If the event occurred in M81 our findings support the the hypothesis that GRB 051103 was due to an SGR giant flare, making it the most distant extragalactic magnetar observed to date.Comment: 8 pages, 3 figures. For a repository of data used in the publication, go to: https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166 . Also see the announcement for this paper on ligo.org at: http://www.ligo.org/science/Publication-GRB051103/index.ph
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