12,845 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
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
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
Sustainability of exercise-induced increases in bone density and skeletal structure
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
How Much Does Money Matter in a Direct Democracy?
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
Structure of glassy lithium sulfate films sputtered in nitrogen (LISON): Insight from Raman spectroscopy and ab initio calculations
Raman spectra of thin solid electrolyte films obtained by sputtering a
lithium sulfate target in nitrogen plasma are measured and compared to ab
initio electronic structure calculations for clusters composed of 28 atoms.
Agreement between measured and calculated spectra is obtained when oxygen atoms
are replaced by nitrogen atoms and when the nitrogen atoms form bonds with each
other. This suggests that the incorporation of nitrogen during the sputtering
process leads to structures in the film, which prevent crystallization of these
thin film salt glasses.Comment: 5 pages, 4 figure
Hydroformylation of propene and 1-hexene catalysed by a alpha-zirconium phosphate supported rhodium-phosphine complex
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