420 research outputs found

    Effects of Sire EPD, Dam Traits and Calf Traits on Calving Difficulty and Subsequent Reproduction of Two-Year-Old Heifers

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    A three-year study evaluated effects of sire birth weight EPD, heifer and calf traits on valuing difficulty and subsequent rebreeding of two-year-old cows. MARC II yearling heifers (n=550) were assigned for breeding to one of four angus sires with birth weight EPD of -2.1, -1.8, +6.3 and +5.9 lb. Of all heifer weights, only dam birth weight affected calving difficulty score. Heifers requiring caesareans had smallest pelvic areas. Calving difficulty increased as calf birth weight and external measurements increased. Low EPD sires produced calves with smaller head and foot circumferences and less dystocia. Degree of calving difficulty did not affect subsequent pregnancy rates, but did delay rebreeding conception date

    Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.

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    Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells

    Measurements of D0D^{0} and D∗D^{*} Production in pp + pp Collisions at s\sqrt{s} = 200 GeV

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    We report measurements of charmed-hadron (D0D^{0}, D∗D^{*}) production cross sections at mid-rapidity in pp + pp collisions at a center-of-mass energy of 200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the hadronic decays D0→K−π+D^{0}\rightarrow K^{-}\pi^{+}, D∗+→D0π+→K−π+π+D^{*+}\rightarrow D^{0}\pi^{+}\rightarrow K^{-}\pi^{+}\pi^{+} and their charge conjugates, covering the pTp_T range of 0.6−-2.0 GeV/cc and 2.0−-6.0 GeV/cc for D0D^{0} and D∗+D^{*+}, respectively. From this analysis, the charm-pair production cross section at mid-rapidity is dσ/dy∣y=0ccˉd\sigma/dy|_{y=0}^{c\bar{c}} = 170 ±\pm 45 (stat.) −59+38^{+38}_{-59} (sys.) μ\mub. The extracted charm-pair cross section is compared to perturbative QCD calculations. The transverse momentum differential cross section is found to be consistent with the upper bound of a Fixed-Order Next-to-Leading Logarithm calculation.Comment: 15 pages, 16 figures. Revised version submitted to Phys. Rev.

    Inclusive charged hadron elliptic flow in Au + Au collisions at sNN\sqrt{s_{NN}} = 7.7 - 39 GeV

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    A systematic study is presented for centrality, transverse momentum (pTp_T) and pseudorapidity (Ρ\eta) dependence of the inclusive charged hadron elliptic flow (v2v_2) at midrapidity(∣Ρ∣<1.0|\eta| < 1.0) in Au+Au collisions at sNN\sqrt{s_{NN}} = 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with different methods, including correlations with the event plane reconstructed in a region separated by a large pseudorapidity gap and 4-particle cumulants (v24v_2{4}), are presented in order to investigate non-flow correlations and v2v_2 fluctuations. We observe that the difference between v22v_2{2} and v24v_2{4} is smaller at the lower collision energies. Values of v2v_2, scaled by the initial coordinate space eccentricity, v2/ξv_{2}/\varepsilon, as a function of pTp_T are larger in more central collisions, suggesting stronger collective flow develops in more central collisions, similar to the results at higher collision energies. These results are compared to measurements at higher energies at the Relativistic Heavy Ion Collider (sNN\sqrt{s_{NN}} = 62.4 and 200 GeV) and at the Large Hadron Collider (Pb + Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV). The v2(pT)v_2(p_T) values for fixed pTp_T rise with increasing collision energy within the pTp_T range studied (<2GeV/c< 2 {\rm GeV}/c). A comparison to viscous hydrodynamic simulations is made to potentially help understand the energy dependence of v2(pT)v_{2}(p_{T}). We also compare the v2v_2 results to UrQMD and AMPT transport model calculations, and physics implications on the dominance of partonic versus hadronic phases in the system created at Beam Energy Scan (BES) energies are discussed.Comment: 20 pages, 12 figures. Version accepted by PR

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE
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