2,749 research outputs found
MAX 4 and MAX 5 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies
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
We propose a six dimensional Universal Extra Dimensions (UED) model
compactified on a real projective plane , 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
gauge field that leads to a spontaneous radius stabilization. Unlike
the sphere and the so-called compactifications, the massless
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
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
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
We observe evidence for CP violation in the decay
using a data sample with an integrated luminosity of 977 fb collected by
the Belle detector at the KEKB asymmetric-energy collider. The CP
asymmetry in the decay is measured to be , 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
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
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.
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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