1,205 research outputs found

    Intake of meat mutagens and risk of prostate cancer in a cohort of U.S. health professionals

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    BACKGROUND: Evidence relating heterocyclic aromatic amines (HCA), associated with high-temperature cooking methods, to prostate cancer risk is inconsistent Methods: In a large US cohort study, intakes of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) and a meat-derived mutagenicity index (MDM) were assessed using a cooking method questionnaire administered in 1996. Until 2010, 2,770 prostate cancer cases were observed among 26,030 participants. RESULTS: Intake of PhIP from red meat was statistically significantly associated with total prostate cancer risk (top vs. bottom quintile HR=1.18, 95% CI 1.03-1.35), but not other HCAs (MeIQx, 1.12, 0.98-1.27, PhIP from white meat, 1.07, 0.94-1.21, DiMeIQx, 1.09, 0.97-1.21) or MDM (1.13, 1.00-1.28). For high grade (Gleason sum 7 with pattern 4+3 and Gleason sum 8-10, n=483 cases) and advanced cancers (n=281), we only observed positive associations for PhIP from red meat (top vs. bottom quintile: high grade: HR=1.44, 95% CI 1.04-1.98, p-trend=0.03; advanced: HR=1.50, 95% 0.99-2.26; p-trend=0.12), but associations for advanced cancers did not reach statistical significance. Observed associations remained similar after adjustment for total, unprocessed or processed red meat intake. CONCLUSION: Observed positive associations between PhIP intake from red meat and prostate cancer, particularly high-grade and possibly also advanced prostate cancer need to be confirmed in other studies. IMPACT: Results do not provide strong evidence that HCAs increase risk of prostate cancers

    Damped Bogoliubov excitations of a condensate interacting with a static thermal cloud

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    We calculate the damping of condensate collective excitations at finite temperatures arising from the lack of equilibrium between the condensate and thermal atoms. We neglect the non-condensate dynamics by fixing the thermal cloud in static equilibrium. We derive a set of generalized Bogoliubov equations for finite temperatures that contain an explicit damping term due to collisional exchange of atoms between the two components. We have numerically solved these Bogoliubov equations to obtain the temperature dependence of the damping of the condensate modes in a harmonic trap. We compare these results with our recent work based on the Thomas-Fermi approximation.Comment: 9 pages, 3 figures included. Submitted to PR

    Dietary patterns during high school and risk of colorectal adenoma in a cohort of middle-aged women

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    Adolescent diet may be etiologically relevant for later risk of colorectal adenoma, a precursor of colorectal cancer. We aimed to examine associations between adolescent dietary patterns (derived using factor analysis) and risk of colorectal adenoma in middle adulthood. We analyzed data from 17,221 women participating in the Nurses' Health Study II, who had completed a validated high school (HS) food frequency questionnaire in 1998 when they were 34-51 years old, and had subsequently undergone at least one lower bowel endoscopy. Between 1998 and 2007, 1,299 women were diagnosed with at least one colorectal adenoma. In multivariable models adjusted for adult dietary patterns, a higher "prudent" pattern during HS, characterized by high consumption of vegetables, fruit and fish was associated with a statistically significantly lower risk of rectal (odds ratio [OR] highest vs. lowest quintile, 0.45, 95% CI 0.27-0.75, p-trend=0.005), but not colon adenomas. A higher "Western" pattern during HS, characterized by high consumption of desserts and sweets, snack foods and red and processed meat, was significantly associated with rectal (OR 1.78, 95% CI 1.12-2.85, p-trend=0.005) and advanced (OR 1.58, 95% CI 1.07-2.33, p-trend=0.08), but not associated with colon or non-advanced adenomas. This study suggests that overall eating patterns during high school may influence later risk of rectal and advanced adenoma, independent of adult diet. Our results support the hypothesis that diet during early life may influence colorectal carcinogenesis

    Anomalous particle-number fluctuations in a three-dimensional interacting Bose-Einstein condensate

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    The particle-number fluctuations originated from collective excitations are investigated for a three-dimensional, repulsively interacting Bose-Einstein condensate (BEC) confined in a harmonic trap. The contribution due to the quantum depletion of the condensate is calculated and the explicit expression of the coefficient in the formulas denoting the particle-number fluctuations is given. The results show that the particle-number fluctuations of the condensate follow the law N22/15 \sim N^{22/15} and the fluctuations vanish when temperature approaches to the BEC critical temperature.Comment: RevTex, 4 page

    Selective Spin-State Switch and Metal-Insulator Transition in \boldmath GdBaCo2O5.5\rm GdBaCo_2O_{5.5}

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    Ultra-high resolution synchrotron diffraction data for GdBaCo2O5.5\rm GdBaCo_2O_{5.5} throw new light on the metal-insulator transition of Co3+^{3+} Ba-cobaltites. An anomalous expansion of CoO6_6 octahedra is observed at the phase transition on heating, while CoO5_5 pyramids show the normal shrinking at the closing of the gap. The insulator-to-metal transition is attributed to a sudden excitation of some electrons in the octahedra (t2g6t_{2g}^6 state) into the Co ege_g band (final t2g4eg2t_{2g}^4e_g^2 state). The t2g5eg1t_{2g}^5e_g^1 state in the pyramids does not change and the structural study also rules out a d3x2r2/d3y2r2d_{3x^2-r^2}/d_{3y^2-r^2} orbital ordering at TMIT_{MI}.Comment: Phys. Rev. B (to appear

    Solar Mikheyev-Smirnov-Wolfenstein Effect with Three Generations of Neutrinos

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    Under the assumption that the density variation of the electrons can be approximated by an exponential function, the solar Mikheyev-Smirnov-Wolfenstein effect is treated for three generations of neutrinos. The generalized hypergeometric functions that result from the exact solution of this problem are studied in detail, and a method for their numerical evaluation is presented. This analysis plays a central role in the determination of neutrino masses, not only the differences of their squares, under the assumption of universal quark-lepton mixing.Comment: 22 pages, LaTeX, including 2 figure

    Effective Actions and Phase Fluctuations in d-wave Superconductors

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    We study effective actions for order parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the cc-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum XY model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero temperature superfluid stiffness, but thermal effects are small for T<<TcT << T_c.Comment: Some numerical estimates corrected and figures changed. to appear in PRB, Sept.1 (2000

    Revisiting the Bs()B^{(*)}_s-Meson Production at the Hadronic Colliders

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    The production of heavy-flavored hadron at the hadronic colliders provides a challenging opportunity to test the validity of pQCD predictions. There are two mechanisms for the Bs()B^{(*)}_s hadroproduction, i.e. the gluon-gluon fusion mechanism via the subprocess g+gBs()+b+sˉg+g\rightarrow B^{(*)}_s+b+\bar{s} and the extrinsic heavy quark mechanism via the subprocesses g+bˉBs()+sˉg+\bar{b}\to B^{(*)}_s +\bar{s} and g+sBs()+bg+s\to B^{(*)}_s +b, both of which shall have sizable contributions in proper kinematic region. Different from the fixed-flavor-number scheme (FFNS) previously adopted in the literature, we study the Bs()B^{(*)}_s hadroproduction under the general-mass variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with the double counting problem from the above two mechanisms. Properties for the Bs()B^{(*)}_s hadroproduction are discussed. To be useful reference, a comparative study of FFNS and GM-VFNS is presented. Both of which can provide reasonable estimations for the Bs()B^{(*)}_s hadroproduction. At the Tevatron, the difference between these two schemes is small, however such difference is obvious at the LHC. The forthcoming more precise data on LHC shall provide a good chance to check which scheme is more appropriate to deal with the Bs()B^{(*)}_s-meson production and to further study the heavy quark components in hadrons.Comment: 18 pages, 8 figures, 4 tables. To match the published version. To be published in Eur.Phys.J.

    An Alternative Method to Deduce Bubble Dynamics in Single Bubble Sonoluminescence Experiments

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    In this paper we present an experimental approach that allows to deduce the important dynamical parameters of single sonoluminescing bubbles (pressure amplitude, ambient radius, radius-time curve) The technique is based on a few previously confirmed theoretical assumptions and requires the knowledge of quantities such as the amplitude of the electric excitation and the phase of the flashes in the acoustic period. These quantities are easily measurable by a digital oscilloscope, avoiding the cost of expensive lasers, or ultrafast cameras of previous methods. We show the technique on a particular example and compare the results with conventional Mie scattering. We find that within the experimental uncertainties these two techniques provide similar results.Comment: 8 pages, 5 figures, submitted to Phys. Rev.

    Optical Sum Rule in Finite Bands

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    In a single finite electronic band the total optical spectral weight or optical sum carries information on the interactions involved between the charge carriers as well as on their band structure. It varies with temperature as well as with impurity scattering. The single band optical sum also bears some relationship to the charge carrier kinetic energy and, thus, can potentially provide useful information, particularly on its change as the charge carriers go from normal to superconducting state. Here we review the considerable advances that have recently been made in the context of high TcT_c oxides, both theoretical and experimental.Comment: Review article accepted for publication in J. Low Temp. Phys. 29 pages, 33 figure
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