10,871 research outputs found

    Six Peaks Visible in the Redshift Distribution of 46,400 SDSS Quasars Agree with the Preferred Redshifts Predicted by the Decreasing Intrinsic Redshift Model

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    The redshift distribution of all 46,400 quasars in the Sloan Digital Sky Survey (SDSS) Quasar Catalog III, Third Data Release, is examined. Six Peaks that fall within the redshift window below z = 4, are visible. Their positions agree with the preferred redshift values predicted by the decreasing intrinsic redshift (DIR) model, even though this model was derived using completely independent evidence. A power spectrum analysis of the full dataset confirms the presence of a single, significant power peak at the expected redshift period. Power peaks with the predicted period are also obtained when the upper and lower halves of the redshift distribution are examined separately. The periodicity detected is in linear z, as opposed to log(1+z). Because the peaks in the SDSS quasar redshift distribution agree well with the preferred redshifts predicted by the intrinsic redshift relation, we conclude that this relation, and the peaks in the redshift distribution, likely both have the same origin, and this may be intrinsic redshifts, or a common selection effect. However, because of the way the intrinsic redshift relation was determined it seems unlikely that one selection effect could have been responsible for both.Comment: 12 pages, 12 figure, accepted for publication in the Astrophysical Journa

    Genetic characterization to dissect the phenotypic complexity of autoimmunity

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    Autoimmune diseases are dependent on multiple genes and unknown environmental factors. Great efforts in the identification of genes conferring susceptibility to autoimmune diseases like Rheumatoid Arthritis (RA) and Multiple Sclerosis (MS) have recently been rewarding. A few genes have so far been associated to several autoimmune disorders and the understanding of the role of these genes in the pathogenesis and the identification of additional genes will be of great use in the designing of new and better therapies. The fine characterization of each disease is of importance in order to define sub-groups, which may respond differently to treatments. The work in this thesis was done in mouse models for RA and MS and is based on four papers where the aim was to identify genes associated with these diseases. We have studied crosses between a susceptible and a resistant mouse strain to assess the genetic context for a disease-linked locus to appear. In an F2 intercross between the two strains, the Eae2 locus on chromosome 15 was previously linked to disease in the MS model Experimental Autoimmune Encephalomyelitis (EAE) through interaction with Eae3 on chromosome 3. The locus homologous to Eae2 on human chromosome 5 was later associated with MS in a Finnish population. In order to identify additional loci, EAE was studied in an F2 intercross where the Eae2 locus was neutralized (paper I) and in a N2 backcross (paper II). In paper III and IV a new strategy to study the interaction between Eae2 and Eae3 is described. Mice congenic for the Eae2 and Eae3 regions were bred in a Partial Advanced Intercross (PAI), which allows for the segregation of genes in the congenic intervals. More than 1000 PAI mice were investigated for Collagen Induced Arthritis (CIA). Different traits of disease were linked to seven sub-QTL within Eae2 and Eae3. Furthermore, the importance of sub-phenotypes in order to identify disease-modifying genes was investigated and is discussed

    How Much Does Money Matter in a Direct Democracy?

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    The fine-structure splitting of quantum confined InxGa1-x Nexcitons is investigated using polarization-sensitive photoluminescence spectroscopy. The majority of the studied emission lines exhibits mutually orthogonal fine-structure components split by 100-340 mu eV, as measured from the cleaved edge of the sample. The exciton and the biexciton reveal identical magnitudes but reversed sign of the energy splitting.Original Publication:Supaluck Amloy, Y T Chen, K F Karlsson, K H Chen, H C Hsu, C L Hsiao, L C Chen and Per-Olof Holtz, Polarization-resolved fine-structure splitting of zero-dimensional InxGa1-xN excitons, 2011, PHYSICAL REVIEW B, (83), 20, 201307.http://dx.doi.org/10.1103/PhysRevB.83.201307Copyright: American Physical Societyhttp://www.aps.org

    Sustainability of exercise-induced increases in bone density and skeletal structure

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    BACKGROUND: The prevalence of osteoporosis with related fragility fractures has increased during the last decades. As physical activity influences the skeleton in a beneficial way, exercise may hypothetically be used as a prophylactic tool against osteoporosis. OBJECTIVE: This review evaluates if exercise-induced skeletal benefits achieved during growth remain in a long-term perspective. DESIGN: PUBLICATIONS WITHIN THE FIELD WERE SEARCHED THROUGH MEDLINE (PUBMED) USING THE SEARCH WORDS: exercise, physical activity, bone mass, bone mineral content (BMC), bone mineral density (BMD) and skeletal structure. We based our inferences on publications with the highest level of evidence, particularly randomised controlled trials (RCT). RESULTS: Benefits in BMD achieved by exercise during growth seem to be eroded at retirement, but benefits in skeletal structure may possibly be retained in a longer perspective. Recreational exercise seems to at least partially maintain exercise-induced skeletal benefits achieved during growth. CONCLUSIONS: Exercise during growth may be followed by long-term beneficial skeletal effects, which could possibly reduce the incidence of fractures. Exercise during adulthood seems to partly preserve these benefits and reduce the age-related bone loss

    The Distribution of Redshifts in New Samples of Quasi-stellar Objects

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    Two new samples of QSOs have been constructed from recent surveys to test the hypothesis that the redshift distribution of bright QSOs is periodic in log(1+z)\log(1+z). The first of these comprises 57 different redshifts among all known close pairs or multiple QSOs, with image separations \leq 10\arcsec, and the second consists of 39 QSOs selected through their X-ray emission and their proximity to bright comparatively nearby active galaxies. The redshift distributions of the samples are found to exhibit distinct peaks with a periodic separation of 0.089\sim 0.089 in log(1+z)\log(1+z) identical to that claimed in earlier samples but now extended out to higher redshift peaks z=2.63,3.45z = 2.63, 3.45 and 4.47, predicted by the formula but never seen before. The periodicity is also seen in a third sample, the 78 QSOs of the 3C and 3CR catalogues. It is present in these three datasets at an overall significance level 10510^{-5} - 10610^{-6}, and appears not to be explicable by spectroscopic or similar selection effects. Possible interpretations are briefly discussed.Comment: submitted for publication in the Astronomical Journal, 15 figure

    Parameterization of the Angular Distribution of Gamma Rays Produced by p-p Interaction in Astronomical Environment

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    We present the angular distribution of gamma rays produced by proton-proton interactions in parameterized formulae to facilitate calculations in astrophysical environments. The parameterization is derived from Monte Carlo simulations of the up-to-date proton-proton interaction model by Kamae et al. (2005) and its extension by Kamae et al. (2006). This model includes the logarithmically rising inelastic cross section, the diffraction dissociation process and Feynman scaling violation. The extension adds two baryon resonance contributions: one representing the Delta(1232) and the other representing multiple resonances around 1600 MeV/c^2. We demonstrate the use of the formulae by calculating the predicted gamma-ray spectrum for two different cases: the first is a pencil beam of protons following a power law and the second is a fanned proton jet with a Gaussian intensity profile impinging on the surrounding material. In both cases we find that the predicted gamma-ray spectrum to be dependent on the viewing angle.Comment: 8 pages, 7 figures, figure 7 updated, accepted for publication in ApJ, text updated to match changes by the editor, two refs updated from preprints to full journal

    Fearing the Disease or the Vaccine:The Case of COVID-19

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    As studies indicate that people perceive COVID-19 as a threatening disease, the demand for a vaccine against the disease could be expected to be high. Vaccine safety concerns might nevertheless outweigh the perceived disease risks when an individual decides whether or not to accept the vaccine. We investigated the role of perceived risk of COVID-19 (i.e., perceived likelihood of infection, perceived disease severity, and disease-related worry) and perceived safety of a prospective vaccine against COVID-19 in predicting intentions to accept a COVID-19 vaccine. Three Finnish samples were surveyed: 825 parents of small children, 205 individuals living in an area with suboptimal vaccination coverage, and 1325 Facebook users nationwide. As points of reference, we compared the perceptions of COVID-19 to those of influenza and measles. COVID-19 was perceived as a threatening disease—more so than influenza and measles. The strongest predictor of COVID-19 vaccination intentions was trusting the safety of the potential vaccine. Those perceiving COVID-19 as a severe disease were also slightly more intent on taking a COVID-19 vaccine. Informing the public about the safety of a forthcoming COVID-19 vaccine should be the focus for health authorities aiming to achieve a high vaccine uptake
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