297 research outputs found

    Production of CO-free H2 from formic acid: a comparative study of the catalytic behavior of Pt metals on a carbon support

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    I detta examensarbete har fokusen varit på att ta fram en design av en tidsaxel och implementera den. Tidsaxeln ska beskriva händelseförloppet av en berättelse som användaren av programmet skrivit. Tidsperioderna sätts på en berättelsenod, som användaren skapar i programmet. Programmet är ett program som är till för att skriva berättelser, som jag har skapat. Programmet kallar jag för tillfället MapMyStory. Genom att införa en tidsaxel är det tänkt att användaren ska få en bättre överblick av berättelsen. Och med hjälp utav tidsaxeln lättare förstå berättelsens händelseförlopp. Jag beskriver hur designen av tidsaxel tagits fram och hur implementationen är gjord, och hur algoritmen för utplaceringen av tidslinjerna fungerar. I rapporten beskriver jag hur jag har arbetat med en nerskalad variant av Scrum. Jag beskriver också hur jag har använt mig utav test driven utveckling för att bekräfta den kod som implementerats

    rCUR: an R package for CUR matrix decomposition

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    BACKGROUND: Many methods for dimensionality reduction of large data sets such as those generated in microarray studies boil down to the Singular Value Decomposition (SVD). Although singular vectors associated with the largest singular values have strong optimality properties and can often be quite useful as a tool to summarize the data, they are linear combinations of up to all of the data points, and thus it is typically quite hard to interpret those vectors in terms of the application domain from which the data are drawn. Recently, an alternative dimensionality reduction paradigm, CUR matrix decompositions, has been proposed to address this problem and has been applied to genetic and internet data. CUR decompositions are low-rank matrix decompositions that are explicitly expressed in terms of a small number of actual columns and/or actual rows of the data matrix. Since they are constructed from actual data elements, CUR decompositions are interpretable by practitioners of the field from which the data are drawn. RESULTS: We present an implementation to perform CUR matrix decompositions, in the form of a freely available, open source R-package called rCUR. This package will help users to perform CUR-based analysis on large-scale data, such as those obtained from different high-throughput technologies, in an interactive and exploratory manner. We show two examples that illustrate how CUR-based techniques make it possible to reduce significantly the number of probes, while at the same time maintaining major trends in data and keeping the same classification accuracy. CONCLUSIONS: The package rCUR provides functions for the users to perform CUR-based matrix decompositions in the R environment. In gene expression studies, it gives an additional way of analysis of differential expression and discriminant gene selection based on the use of statistical leverage scores. These scores, which have been used historically in diagnostic regression analysis to identify outliers, can be used by rCUR to identify the most informative data points with respect to which to express the remaining data points

    Distances sets that are a shift of the integers and Fourier basis for planar convex sets

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    The aim of this paper is to prove that if a planar set AA has a difference set Δ(A)\Delta(A) satisfying Δ(A)Z++s\Delta(A)\subset \Z^++s for suitable ss than AA has at most 3 elements. This result is motivated by the conjecture that the disk has not more than 3 orthogonal exponentials. Further, we prove that if AA is a set of exponentials mutually orthogonal with respect to any symmetric convex set KK in the plane with a smooth boundary and everywhere non-vanishing curvature, then # (A \cap {[-q,q]}^2) \leq C(K) q where C(K)C(K) is a constant depending only on KK. This extends and clarifies in the plane the result of Iosevich and Rudnev. As a corollary, we obtain the result from \cite{IKP01} and \cite{IKT01} that if KK is a centrally symmetric convex body with a smooth boundary and non-vanishing curvature, then L2(K)L^2(K) does not possess an orthogonal basis of exponentials

    Long-Term Estrogen Receptor Beta Agonist Treatment Modifies the Hippocampal Transcriptome in Middle-Aged Ovariectomized Rats.

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    Estradiol (E2) robustly activates transcription of a broad array of genes in the hippocampal formation of middle-aged ovariectomized rats via estrogen receptors (ERalpha, ERbeta, and G protein-coupled ER). Selective ERbeta agonists also influence hippocampal functions, although their downstream molecular targets and mechanisms are not known. In this study, we explored the effects of long-term treatment with ERbeta agonist diarylpropionitrile (DPN, 0.05 mg/kg/day, sc.) on the hippocampal transcriptome in ovariectomized, middle-aged (13 month) rats. Isolated hippocampal formations were analyzed by Affymetrix oligonucleotide microarray and quantitative real-time PCR. Four hundred ninety-seven genes fulfilled the absolute fold change higher than 2 (FC > 2) selection criterion. Among them 370 genes were activated. Pathway analysis identified terms including glutamatergic and cholinergic synapse, RNA transport, endocytosis, thyroid hormone signaling, RNA degradation, retrograde endocannabinoid signaling, and mRNA surveillance. PCR studies showed transcriptional regulation of 58 genes encoding growth factors (Igf2, Igfb2, Igf1r, Fgf1, Mdk, Ntf3, Bdnf), transcription factors (Otx2, Msx1), potassium channels (Kcne2), neuropeptides (Cck, Pdyn), peptide receptors (Crhr2, Oprm1, Gnrhr, Galr2, Sstr1, Sstr3), neurotransmitter receptors (Htr1a, Htr2c, Htr2a, Gria2, Gria3, Grm5, Gabra1, Chrm5, Adrb1), and vesicular neurotransmitter transporters (Slc32a1, Slc17a7). Protein-protein interaction analysis revealed networking of clusters associated with the regulation of growth/troph factor signaling, transcription, translation, neurotransmitter and neurohormone signaling mechanisms and potassium channels. Collectively, the results reveal the contribution of ERbeta-mediated processes to the regulation of transcription, translation, neurogenesis, neuromodulation, and neuroprotection in the hippocampal formation of ovariectomized, middle-aged rats and elucidate regulatory channels responsible for DPN-altered functional patterns. These findings support the notion that selective activation of ERbeta may be a viable approach for treating the neural symptoms of E2 deficiency in menopause

    Collinear points in permutations

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    Abstract. Consider the following problem: how many collinear triples of points must a transversal of Z n × Z n have? This question is connected with venerable issues in discrete geometry. We show that the answer, for n prime, is between (n − 1)/4 and (n − 1)/2, and consider an analogous question for collinear quadruples. We conjecture that the upper bound is the truth and suggest several other interesting problems in this area

    Catalytic abatement of trichloroethylene over Mo and/or W-based bronzes

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    [EN] In this paper we present the results of the synthesis, characterization and catalytic behaviour of Mo(W)¿Nb¿V¿O mixed metal oxides bronzes for the catalytic oxidation of trichloroethylene. The catalysts were prepared hydrothermally with different Mo/W/Nb/V/P atomic ratio and heat-treated at 500 and 700 °C. They were characterized by several techniques as N2-adsorption, X-ray diffraction, FTIR, SEM-EDS, temperature programmed desorption, temperature programmed reduction, UV¿vis, Fourier transformed infrared spectroscopy of adsorbed pyridine and 18O/16O isotope exchange. X-ray diffraction patterns (XRD) of samples heat-treated at 500 °C suggest the presence of a semi-crystalline material with a diffraction peak at ca. 2¿ = 22.2°, while XRD patterns of samples heat-treated at 700 °C show the formation of a tetragonal tungsten bronze (TTB) structure. The activity for the catalytic abatement of trichloroethylene strongly depends on the heat-treatment temperature and the catalyst composition. Thus, samples with W/(Mo + W) atomic ratios of 0.25-0.75 and heat-treated at 500 °C are the most active ones. The enhanced activity has been related to the remarkable higher surface area of the catalyst and to the catalyst composition which influences the acid characteristics as well as the reducibility and reoxidation of the catalysts. The importance of the oxygen dissociation on the catalyst surface and the diffusion of oxygen species through the catalyst are also discussed.The authors wish to thank DGICYT in Spain (Project CTQ2009-14495 and CSD2009-00050-CONSOLIDER/INGENIO 2010) and Universitat Politecnica de Valencia for the financial support. N.B.R. acknowledges Catedra Cemex Sostenibilidad (UPV) for a fellowship. M.D.S. acknowledges Universitat Politecnica de Valencia for a fellowship.Blanch Raga, N.; Soriano Rodríguez, MD.; Palomares Gimeno, AE.; Concepción Heydorn, P.; Martínez Triguero, LJ.; López Nieto, JM. (2013). Catalytic abatement of trichloroethylene over Mo and/or W-based bronzes. Applied Catalysis B: Environmental. 130-131:36-43. https://doi.org/10.1016/j.apcatb.2012.10.016S3643130-13
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