2,749 research outputs found

    MAX 4 and MAX 5 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies

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    We account for experimental and observational uncertainties in likelihood analyses of cosmic microwave background (CMB) anisotropy data from the MAX 4 and MAX 5 experiments. These analyses use CMB anisotropy spectra predicted in open and spatially-flat Lambda cold dark matter cosmogonies. Amongst the models considered, the combined MAX data set is most consistent with the CMB anisotropy shape in Omega_0 ~ 0.1-0.2 open models and less so with that in old (t_0 >~ 15 - 16 Gyr, i.e., low h), high baryon density (Omega_B >~ 0.0175/h^2), low density (Omega_0 ~ 0.2 - 0.4), flat-Lambda models. The MAX data alone do not rule out any of the models we consider at the 2-sigma level. Model normalizations deduced from the combined MAX data are consistent with those drawn from the UCSB South Pole 1994 data, except for the flat bandpower model where MAX favours a higher normalization. The combined MAX data normalization for open models with Omega_0 ~ 0.1-0.2 is higher than the upper 2-sigma value of the DMR normalization. The combined MAX data normalization for old (low h), high baryon density, low-density flat-Lambda models is below the lower 2-sigma value of the DMR normalization. Open models with Omega_0 ~ 0.4-0.5 are not far from the shape most favoured by the MAX data, and for these models the MAX and DMR normalizations overlap. The MAX and DMR normalizations also overlap for Omega_0 = 1 and some higher h, lower Omega_B, low-density flat-Lambda models.Comment: Latex, 37 pages, uses aasms4 styl

    Universal Extra Dimensions on Real Projective Plane

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    We propose a six dimensional Universal Extra Dimensions (UED) model compactified on a real projective plane RP2RP^2, a two-sphere with its antipodal points being identified. We utilize the Randjbar-Daemi-Salam-Strathdee spontaneous sphere compactification with a monopole configuration of an extra U(1)XU(1)_X gauge field that leads to a spontaneous radius stabilization. Unlike the sphere and the so-called S2/Z2S^2/Z_2 compactifications, the massless U(1)XU(1)_X gauge boson is safely projected out. We show how a compactification on a non-orientable manifold results in a chiral four dimensional gauge theory by utilizing 6D chiral gauge and Yukawa interactions. The resultant Kaluza-Klein mass spectra are distinct from the ordinary UED models compactified on torus. We briefly comment on the anomaly cancellation and also on a possible dark matter candidate in our model.Comment: 14 pages, 1 figure (v1); Comments and references added, 15 pages (v2); Comments and references added, 15 pages, version to appear in Phys. Lett. B (v3

    First Confirmed Detection of a Bipolar Molecular Outflow from a Young Brown Dwarf

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    Studying the earliest stages in the birth of stars is crucial for understanding how they form. Brown dwarfs with masses between that of stars and planets are not massive enough to maintain stable hydrogen-burning fusion reactions during most of their lifetime. Their origins are subject to much debate in recent literature because their masses are far below the typical mass where core collapse is expected to occur. We present the first confirmed evidence that brown dwarfs undergo a phase of molecular outflow that is typical of young stars. Using the Submillimeter Array, we have obtained a map of a bipolar molecular outflow from a young brown dwarf. We estimate an outflow mass of 1.6 x 10^-4 M_Sun and a mass-loss rate of 1.4 x 10^-9 M_Sun. These values are over two orders of magnitude smaller than the typical ones for T Tauri stars. From our millimiter continuum data and our own analysis of Spitzer infrared photometry, we estimate that the brown dwarf has a disk with a mass of 8 x 10^-3 M_Sun and an outer disk radius of 80 AU. Our results demonstrate that the bipolar molecular outflow operates down to planetary masses, occurring in brown dwarfs as a scaled-down version of the universal process seen in young stars.Comment: accepted by ApJ Letter

    Comparative Analysis of AB vs. ABO-specific Plasma for Desensitization in Blood Group O Recipients: An In Vitro Study

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    Neutralizing capacity measurement (NCM) of soluble ABH substances (SAS) in plasma was assessed to guide the selection of the appropriate ABO group of fresh-frozen plasma (FFP) for plasma exchange (PE) in blood group O recipients with ABO-incompatible transplantations. Neutralizing capacity was assessed by measuring anti-A and/or anti-B titers in samples comprising one unit of O FFP and 10 O EDTA plasma samples and subtracting the binary logarithm of the titer in each group with a saline dilution. Ten EDTA plasma samples with Lewis b (Leb) antigen positivity and 10 sets of pooled FFP from each blood group were used as diluents. In O FFP, the NCM values (mean±SD) were 3.4±0.52 (2.6±0.52) and 2.6±0.52 (1.5±0.3) in B and AB for IgM (total antibody) anti-B (both P <0.001), and in the 10 O EDTA plasma samples, they were 3.9±0.88 (3.1±0.88) and 3.2±0.79 (2.4±0.97) for IgM (P =0.0013) and total anti-B (P =0.025), respectively. In vitro analysis revealed that B FFP is more effective than AB FFP in reducing IgM and total anti-B antibody titers in O recipients, regardless of Leb antigen positivity

    Evidence for CP Violation in the Decay D+KS0π+D^+\rightarrow K^0_S\pi^+

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    We observe evidence for CP violation in the decay D+KS0π+D^+\rightarrow K^0_S\pi^+ using a data sample with an integrated luminosity of 977 fb1^{-1} collected by the Belle detector at the KEKB e+ee^+e^- asymmetric-energy collider. The CP asymmetry in the decay is measured to be (0.363±0.094±0.067)(-0.363\pm0.094\pm0.067)%, which is 3.2 standard deviations away from zero, and is consistent with the expected CP violation due to the neutral kaon in the final state.Comment: 6 pages, 3 figure

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    An experience of the use of Anti-HBc and Anti-HBs for blood donor screening tests at a tertiary hospital blood center in Korea.

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    BACKGROUND: The aim of this study was to report the first experience of using tests of antibody to hepatitis B core antigen (anti-HBc) and antibody to hepatitis B surface antigen (anti-HBs) for the selection of blood donors in a tertiary hospital blood center in Korea. METHODS: From January 2005 to December 2007, the data of all eligible donors according to the Korean Blood Regulation Law were analyzed. Anti-HBc testing was performed in all donors, but anti-HBs was tested only in anti-HBc seropositive donors. Anti-HBs negative but anti-HBc positive donors were regarded as ineligible for blood donation. Cost for donor testing was calculated based on Korean health insurance payment schedule from 2005 to 2007. RESULTS: The seroprevalence of anti-HBc in blood donors was 23.2% (162/699) and increased with increasing age. The proportion of ineligible donors for blood collection was 2.7% (19/699) of total donors and 11.6% (19/162) of anti-HBc seropositive donors. The cost of testing for anti-HBc and anti-HBs was estimated to be about 40% of the total screening cost. CONCLUSIONS: Although additional donor screening tests for anti-HBc and anti-HBs requires increased cost and relatively small number of donors are additionally excluded by these tests, they are considered to be helpful for the safety of blood products, because our blood center has characteristics with small number of donors and relatively high percentage of donors in the age group of thirties and older
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