218 resultados para Vidal i Xifré, Carme
Resumo:
A list of 681 UBVRI secondary standard stars for CCD photometry is presented. Visual magnitude ranges from 9.7 to 19.4, and the B-V colour index varies from 1.15 to 1.97. The stars are grouped into 11 different fields, each of them is generally observable in a single CCD frame. The stars are located near Landolt UBVRI equatorial standards, accessible to telescopes in both hemispheres, and mainly within the 5 - 8 hours range of right ascension. Photometry, equatorial coordinates and finding charts are provided.
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In order to complete the photometric data of the Gliese (1969) 'Catalog of Nearby Stars', and in addition use these data for the Hipparcos space astrometry mission, program stars have been selected from the catalog and its supplements on the basis of their having an incomplete set of UBVRI photometric data of magnitude lower than 13. The program developed rejects determinations of any magnitude or color index having a residual greater than 2(sigma-prime), where sigma-prime is the standard deviation for the determinations of unit weight.
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UBVRI photoelectric photometry is presented for 269 late spectral type, high proper motion stars belonging to the 'Lowell Proper Motion Survey' and included in the present version of the Hipparcos Input Catalogue. The observations and data reduction are described. The external errors obtained by comparison of the results with those obtained in other studies are presented.
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UBVRI data are presented for a set of 229 late-type stars, most of them being high proper motion stars. All these data are part of the Input Catalog planned observations for the Hipparcos mission.
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UVBY-Beta photometric data are presented for 67 stars in the region of alpha-Persei and their relationship to the cluster is analyzed. These data allowed us to confirm at least 16 new members of the alpha-Persei open cluster.
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As indicated by Grenon (1989), the data of the present series of reports on the UBVRI photometry of late-type stars in the Hipparcos Input Catalog are to be employed in computations of Hipparcos observing time, as well as in evaluating the observability of faint stars by the satellite. Attention is here given to late type stars in the V = 8-12 range, including distant red giants in the Galactic plane (Hipparcos proposal 189), as well as high proper motion stars included in the G, LTT, LP, and MCC catalogs.
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uvby H-beta photometry has been obtained for a sample of 93 selected main sequence A stars. The purpose was to determine accurate effective temperatures, surface gravities, and absolute magnitudes for an individual determination of ages and parallaxes, which have to be included in a more extensive work analyzing the kinematic properties of A V stars. Several calibrations and methods to determine the above mentioned parameters have been reviewed, allowing the design of a new algorithm for their determination. The results obtained using this procedure were tested in a previous paper using uvby H-beta data from the Hauck and Mermilliod catalogue, and comparing the rusulting temperatures, surface gravities and absolute magnitudes with empirical determinations of these parameters.
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Results are presented on Stromgren-Crawford uvby-beta photometry carried out at Calar Alto (Spain) for 45 stars in the Cepheus OB3 region covering an apparent area of 6 deg x 6 deg. The relationship of these stars with the association is examined. Three of these stars (BD +62 deg 2114, BD +62 deg 2152, and BD +62 deg 2156) are identified as members of this association, while two more (BD +64 deg 1714 and BD +64 deg 1717) are classified as possible members. It is noted that intrinsic colors and absolute magnitudes of member stars are consistent with the hypothesis of Blaauw (1964) and Garmany (1973) of the existence of two subgroups with different evolutionary phases.
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In an analysis of proper motions of O and B stars contained the Input Catalogue for Hipparcos, we have found a clear deviation from the expected pattern of systematic motions which can be readily identified with the associations Cygnus OB1 and Cygnus OB9, located near de the edge of the Cygnus Superbubble. Teha anomalous motions are directed outwards from the center of the Superbubble, which is coincident with tha association Cygnus OB2. This seems to support the hypothesis of a strong stellar and supernova activity in Cygnus 0B2 giving rise to the Superbubble and, by means of gravitational instabilities in its boundaries, to Cygnus 0B1 and Cygnus OB9. New uvby-beta aperture photometry of selected O and B stars in the area of Cygnus OB1 and Cygnus OB9 is also presented and analyzed in this paper.
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We present I-band deep CCD exposures of the fields of galactic plane radio variables. An optical counterpart, based on positional coincidence, has been found for 15 of the 27 observed program objects. The Johnson I magnitude of the sources identified is in the range 18-21.
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The present study is an analysis of IR sources in the Alpha Persei open cluster region from the IRAS Point Source Catalog and from ground-based photometric observations. Cross-identification between stars in the region and IRAS Point Source Catalog was performed and nine new associations were found. BVRI Johnson photometry for 24 of the matched objects have been carried out. Physical identity of visual and IRAS sources and relationship to the Alpha Persei open cluster are discussed.
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Background. Microglia and astrocytes respond to homeostatic disturbances with profound changes of gene expression. This response, known as glial activation or neuroinflammation, can be detrimental to the surrounding tissue. The transcription factor CCAAT/enhancer binding protein ß (C/EBPß) is an important regulator of gene expression in inflammation but little is known about its involvement in glial activation. To explore the functional role of C/EBPß in glial activation we have analyzed pro-inflammatory gene expression and neurotoxicity in murine wild type and C/EBPß-null glial cultures. Methods. Due to fertility and mortality problems associated with the C/EBPß-null genotype we developed a protocol to prepare mixed glial cultures from cerebral cortex of a single mouse embryo with high yield. Wild-type and C/EBPß-null glial cultures were compared in terms of total cell density by Hoechst-33258 staining; microglial content by CD11b immunocytochemistry; astroglial content by GFAP western blot; gene expression by quantitative real-time PCR, western blot, immunocytochemistry and Griess reaction; and microglial neurotoxicity by estimating MAP2 content in neuronal/microglial cocultures. C/EBPß DNA binding activity was evaluated by electrophoretic mobility shift assay and quantitative chromatin immunoprecipitation. Results. C/EBPß mRNA and protein levels, as well as DNA binding, were increased in glial cultures by treatment with lipopolysaccharide (LPS) or LPS + interferon ¿ (IFN¿). Quantitative chromatin immunoprecipitation showed binding of C/EBPß to pro-inflammatory gene promoters in glial activation in a stimulus- and gene-dependent manner. In agreement with these results, LPS and LPS+IFN¿ induced different transcriptional patterns between pro-inflammatory cytokines and NO synthase-2 genes. Furthermore, the expressions of IL-1ß and NO synthase-2, and consequent NO production, were reduced in the absence of C/EBPß. In addition, neurotoxicity elicited by LPS+IFN¿-treated microglia co-cultured with neurons was completely abolished by the absence of C/EBPß in microglia.
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Background: Limited data on a short series of patients suggest that lymphocytic enteritis (classically considered as latent coeliac disease) may produce symptoms of malabsorption, although the true prevalence of this situation is unknown. Serological markers of coeliac disease are of little diagnostic value in identifying these patients. Aims: To evaluate the usefulness of human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy for the detection of gluten-sensitive enteropathy in first-degree relatives of patients with coeliac disease and to assess the clinical relevance of lymphocytic enteritis diagnosed with this screening strategy. Patients and methods: 221 first-degree relatives of 82 DQ2+ patients with coeliac disease were consecutively included. Duodenal biopsy (for histological examination and tissue transglutaminase antibody assay in culture supernatant) was carried out on all DQ2+ relatives. Clinical features, biochemical parameters and bone mineral density were recorded. Results: 130 relatives (58.8%) were DQ2+, showing the following histological stages: 64 (49.2%) Marsh 0; 32 (24.6%) Marsh I; 1 (0.8%) Marsh II; 13 (10.0%) Marsh III; 15.4% refused the biopsy. 49 relatives showed gluten sensitive enteropathy, 46 with histological abnormalities and 3 with Marsh 0 but positive tissue transglutaminase antibody in culture supernatant. Only 17 of 221 relatives had positive serological markers. Differences in the diagnostic yield between the proposed strategy and serology were significant (22.2% v 7.2%, p<0.001). Relatives with Marsh I and Marsh II¿III were more often symptomatic (56.3% and 53.8%, respectively) than relatives with normal mucosa (21.1%; p=0.002). Marsh I relatives had more severe abdominal pain (p=0.006), severe distension (p=0.047) and anaemia (p=0.038) than those with Marsh 0. The prevalence of abnormal bone mineral density was similar in relatives with Marsh I (37%) and Marsh III (44.4%). Conclusions: The high number of symptomatic patients with lymphocytic enteritis (Marsh I) supports the need for a strategy based on human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy in relatives of patients with coeliac disease and modifies the current concept that villous atrophy is required to prescribe a gluten-free diet.
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Background/Aims: The epidemiology of Chagas disease, until recently confined to areas of continental Latin America, has undergone considerable changes in recent decades due to migration to other parts of the world, including Spain. We studied the prevalence of Chagas disease in Latin American patients treated at a health center in Barcelona and evaluated its clinical phase. We make some recommendations for screening for the disease. Methodology/Principal Findings: We performed an observational, cross-sectional prevalence study by means of an immunochromatographic test screening of all continental Latin American patients over the age of 14 years visiting the health centre from October 2007 to October 2009. The diagnosis was confirmed by serological methods: conventional in-house ELISA (cELISA), a commercial kit (rELISA) and ELISA using T cruzi lysate (Ortho-Clinical Diagnostics) (oELISA). Of 766 patients studied, 22 were diagnosed with T. cruzi infection, showing a prevalence of 2.87% (95% CI, 1.6-4.12%). Of the infected patients, 45.45% men and 54.55% women, 21 were from Bolivia, showing a prevalence in the Bolivian subgroup (n = 127) of 16.53% (95% CI, 9.6-23.39%). All the infected patients were in a chronic phase of Chagas disease: 81% with the indeterminate form, 9.5% with the cardiac form and 9.5% with the cardiodigestive form. All patients infected with T. cruzi had heard of Chagas disease in their country of origin, 82% knew someone affected, and 77% had a significant history of living in adobe houses in rural areas. Conclusions: We found a high prevalence of T. cruzi infection in immigrants from Bolivia. Detection of T. cruzi¿infected persons by screening programs in non-endemic countries would control non-vectorial transmission and would benefit the persons affected, public health and national health systems.