739 research outputs found

    Derivation of Distances with the Tully-Fisher Relation: The Antlia Cluster

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    The Tully-Fisher relation is a correlation between the luminosity and the HI 21cm line width in spiral galaxies (LLW relation). It is used to derive galaxy distances in the interval 7 to 100 Mpc. Closer, the Cepheids, TRGB and Surface Brightness Fluctuation methods give a better accuracy. Further, the SNIa are luminous objects still available for distance measurement purposes, though with a dramatically lower density grid of measurements on the sky. Galaxies in clusters are all at the same distance from the observer. Thus the distance of the cluster derived from a large number of galaxies (N) has an error reduced according to the square root of N. However, not all galaxies in a cluster are suitable for the LLW measurement. The selection criteria we use are explained hereafter; the important point being to avoid Malmquist bias and to not introduce any systematics in the distance measurement.Comment: Moriond0

    Non-functional immunoglobulin G transcripts in a case of hyper-immunoglobulin M syndrome similar to type 4

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    86% of immunoglobulin G (IgG) heavy-chain gene transcripts were found to be non-functional in the peripheral blood B cells of a patient initially diagnosed with common variable immunodeficiency, who later developed raised IgM, whereas no non-functionally rearranged transcripts were found in the cells of seven healthy control subjects. All the patient's IgM heavy-chain and Îş light-chain transcripts were functional, suggesting that either non-functional rearrangements were being selectively class-switched to IgG, or that receptor editing was rendering genes non-functional after class-switching. The functional Îł-chain sequences showed a normal rate of somatic hypermutation while non-functional sequences contained few somatic mutations, suggesting that most came from cells that had no functional gene and therefore were not receiving signals for hypermutation. However, apoptosis of peripheral blood lymphocytes was not impaired. No defects have been found in any of the genes currently known to be responsible for hyper-IgM syndrome but the phenotype fits best to type 4

    Can habitat specialisation maintain a mosaic hybrid zone in marine bivalves?

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    Maintaining the integrity of differentiated genomes in marine organisms needs efficient isolation mechanisms, because planktonic larval dispersion provides contacts between taxa. Habitat specialisation is interesting in this respect, because it can both prevent interspecific crosses (each taxon reproduces in its own habitat) and eliminate hybrids (typically less fit than a parental taxon in each habitat). The contact zone between smooth-shelled mussels Mytilus edulis and M. galloprovincialis in Europe is a good example, as allozyme genotypes typical of both taxa seem to segregate into different habitats. However, allozymes may be selected directly and it is not known whether the same pattern can be extended to the whole genome. Here, we used 6 presumably neutral PCR markers to investigate habitat specialisation, focussing on the Bay of Quiberon, a small region in the midst of the contact zone between the 2 taxa. Confirming allozyme findings, our results indicate that habitat specialisation is apparent at the genomic scale, as M, edulis-like genotypes are found in sheltered or open-sea sites under freshwater influence, whereas M, galloprovincialis-like genotypes occupy exposed sites. Hybrid (or mixed) populations are found in open-sea or sheltered areas without freshwater influence. Therefore, habitat specialisation does contribute to the interspecific barrier. However, this mechanism seems insufficient to completely prevent the mixing of the 2 genomes, as mixed populations exist and provide opportunity for further hybridisation. Large gametic disequilibria within hybrid populations indicate the existence of restrictions to genetic exchange between the 2 taxa, even within a single habitat. Habitat-independent isolation mechanisms must, therefore, exist in addition

    Photometric quality of Dome C for the winter 2008 from ASTEP South

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    ASTEP South is an Antarctic Search for Transiting Exo- Planets in the South pole field, from the Concordia station, Dome C, Antarctica. The instrument consists of a thermalized 10 cm refractor observing a fixed 3.88\degree x 3.88\degree field of view to perform photometry of several thousand stars at visible wavelengths (700-900 nm). The first winter campaign in 2008 led to the retrieval of nearly 1600 hours of data. We derive the fraction of photometric nights by measuring the number of detectable stars in the field. The method is sensitive to the presence of small cirrus clouds which are invisible to the naked eye. The fraction of night-time for which at least 50% of the stars are detected is 74% from June to September 2008. Most of the lost time (18.5% out of 26%) is due to periods of bad weather conditions lasting for a few days ("white outs"). Extended periods of clear weather exist. For example, between July 10 and August 10, 2008, the total fraction of time (day+night) for which photometric observations were possible was 60%. This confirms the very high quality of Dome C for nearly continuous photometric observations during the Antarctic winter

    APPLaUD: access for patients and participants to individual level uninterpreted genomic data.

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    BACKGROUND: There is a growing support for the stance that patients and research participants should have better and easier access to their raw (uninterpreted) genomic sequence data in both clinical and research contexts. MAIN BODY: We review legal frameworks and literature on the benefits, risks, and practical barriers of providing individuals access to their data. We also survey genomic sequencing initiatives that provide or plan to provide individual access. Many patients and research participants expect to be able to access their health and genomic data. Individuals have a legal right to access their genomic data in some countries and contexts. Moreover, increasing numbers of participatory research projects, direct-to-consumer genetic testing companies, and now major national sequencing initiatives grant individuals access to their genomic sequence data upon request. CONCLUSION: Drawing on current practice and regulatory analysis, we outline legal, ethical, and practical guidance for genomic sequencing initiatives seeking to offer interested patients and participants access to their raw genomic data

    The secondary eclipses of WASP-19b as seen by the ASTEP 400 telescope from Antarctica

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    The ASTEP (Antarctica Search for Transiting ExoPlanets) program was originally aimed at probing the quality of the Dome C, Antarctica for the discovery and characterization of exoplanets by photometry. In the first year of operation of the 40 cm ASTEP 400 telescope (austral winter 2010), we targeted the known transiting planet WASP-19b in order to try to detect its secondary transits in the visible. This is made possible by the excellent sub-millimagnitude precision of the binned data. The WASP-19 system was observed during 24 nights in May 2010. The photometric variability level due to starspots is about 1.8% (peak-to-peak), in line with the SuperWASP data from 2007 (1.4%) and larger than in 2008 (0.07%). We find a rotation period of WASP-19 of 10.7 +/- 0.5 days, in agreement with the SuperWASP determination of 10.5 +/- 0.2 days. Theoretical models show that this can only be explained if tidal dissipation in the star is weak, i.e. the tidal dissipation factor Q'star > 3.10^7. Separately, we find evidence for a secondary eclipse of depth 390 +/- 190 ppm with a 2.0 sigma significance, a phase consistent with a circular orbit and a 3% false positive probability. Given the wavelength range of the observations (420 to 950 nm), the secondary transit depth translates into a day side brightness temperature of 2690(-220/+150) K, in line with measurements in the z' and K bands. The day side emission observed in the visible could be due either to thermal emission of an extremely hot day side with very little redistribution of heat to the night side, or to direct reflection of stellar light with a maximum geometrical albedo Ag=0.27 +/- 0.13. We also report a low-frequency oscillation well in phase at the planet orbital period, but with a lower-limit amplitude that could not be attributed to the planet phase alone, and possibly contaminated with residual lightcurve trends.Comment: Accepted for publication in Astronomy and Astrophysics, 13 pages, 13 figure

    Definition of Mafa-A and -B haplotypes in pedigreed cynomolgus macaques (Macaca fascicularis)

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    The major histocompatibility complex (MHC) class I B gene/allelic repertoire was investigated in a pedigreed population of cynomolgus macaques of mixed Indonesian/Malaysian origin. The Mafa-B alleles detected in this cohort are mostly specific for a given geographic area, and only a small number of alleles appears to be shared with other populations. This suggests the fast evolution of Mafa-B alleles due to adaptation to new environments. In contrast to humans, the B locus in Old World monkeys displays extensive copy number variation. The Mafa-B and previously defined -A gene combinations segregate in families and thus allowed the definition of extended haplotypes. In many cases it was possible to assign a particular Mafa-I allele to one of these Mafa-A/B haplotypes as well. The presence of a large number of stable haplotypes in this cohort of animals, which was pedigreed for up to eight generations, looks promising for developing discriminative MHC typing tools that are less cumbersome. Furthermore, the discovery of 53 unreported Mafa-B sequences expands the lexicon of alleles significantly, and may help in understanding the complex organisation of the macaque B region
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