725 research outputs found

    Evaluation of the ALMA Prototype Antennas

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    The ALMA North American and European prototype antennas have been evaluated by a variety of measurement systems to quantify the major performance specifications. Nearfield holography was used to set the reflector surfaces to 17 microns RMS. Pointing and fast switching performance was determined with an optical telescope and by millimeter wavelength radiometry, yielding 2 arcsec absolute and 0.6 arcsec offset pointing accuracies. Path length stability was measured to be less than or approximately equal to 20 microns over 10 minute time periods using optical measurement devices. Dynamical performance was studied with a set of accelerometers, providing data on wind induced tracking errors and structural deformation. Considering all measurements made during this evaluation, both prototype antennas meet the major ALMA antenna performance specifications.Comment: 83 pages, 36 figures, AASTex format, to appear in PASP September 2006 issu

    Class Position of Immigrant Workers in a Post-Industrial Economy: The Dutch Case

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    In this paper, the issue of changing labour-market opportunities and the position of members of minority groups in advanced service economies is addressed, focusing on the Dutch case. We distinguish between two social hierarchies, one of traditional ‘fordist’ occupations and one of post-fordist occupations. Compared to the native Dutch, all immigrant groups are over-represented at the bottom of the labour market, both in the fordist and in the postindustrial hierarchy. Increased immigrant labour-market participation in the 1990s was accompanied by a strong rise in the number of flexible labour contracts. Native Dutch also work more frequently on flexible labour contracts, but not to the same extent as immigrants. The lower occupational level of the Surinamese, Antilleans and other non-Western immigrants employed in post-industrial occupations can be attributed to their low educational level. This is not true, however, for Turks, Moroccans and other non-Western immigrants employed in fordist occupations. Their low occupational level can not be completely explained by their low educational level. The effects of changes in the economic structure differ for ethnic groups, depending on their past employment, their cultural capital and the institutional framework in which they have to operate

    Роль совершенствования бухгалтерского учета в управлении производственными запасами

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    Целью проведения исследования является обоснование направлений повышения эффективности использования материальных производственных запасов на предприятии в условиях рыночной экономики

    Bioinformatic Inference of Specific and General Transcription Factor Binding Sites in the Plant Pathogen Phytophthora infestans

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    Plant infection by oomycete pathogens is a complex process. It requires precise expression of a plethora of genes in the pathogen that contribute to a successful interaction with the host. Whereas much effort has been made to uncover the molecular systems underlying this infection process, mechanisms of transcriptional regulation of the genes involved remain largely unknown. We performed the first systematic de-novo DNA motif discovery analysis in Phytophthora. To this end, we utilized the genome sequence of the late blight pathogen Phytophthora infestans and two related Phytophthora species (P. ramorum and P. sojae), as well as genome-wide in planta gene expression data to systematically predict 19 conserved DNA motifs. This catalog describes common eukaryotic promoter elements whose functionality is supported by the presence of orthologs of known general transcription factors. Together with strong functional enrichment of the common promoter elements towards effector genes involved in pathogenicity, we obtained a new and expanded picture of the promoter structure in P. infestans. More intriguingly, we identified specific DNA motifs that are either highly abundant or whose presence is significantly correlated with gene expression levels during infection. Several of these motifs are observed upstream of genes encoding transporters, RXLR effectors, but also transcriptional regulators. Motifs that are observed upstream of known pathogenicity-related genes are potentially important binding sites for transcription factors. Our analyses add substantial knowledge to the as of yet virtually unexplored question regarding general and specific gene regulation in this important class of pathogens. We propose hypotheses on the effects of cis-regulatory motifs on the gene regulation of pathogenicity-related genes and pinpoint motifs that are prime targets for further experimental validation
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