232 research outputs found

    Hidden talents in context: Cognitive performance with abstract versus ecological stimuli among adversity-exposed youth

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    Adversity-exposed youth tend to score lower on cognitive tests. However, the hidden talents approach proposes some abilities are enhanced by adversity, especially under ecologically relevant conditions. Two versions of an attention-shifting and working memory updating task—one abstract, one ecological—were administered to 618 youth (Mage = 13.62, SDage = 0.81; 48.22% female; 64.56% White). Measures of environmental unpredictability, violence, and poverty were collected to test adversity × task version interactions. There were no interactions for attention shifting. For working memory updating, youth exposed to violence and poverty scored lower than their peers with abstract stimuli but almost just as well with ecological stimuli. These results are striking compared to contemporary developmental science, which often reports lowered performance among adversity-exposed youth

    A Gribov equation for the photon Green's function

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    We present a derivation of the Gribov equation for the gluon/photon Green's function D(q). Our derivation is based on the second derivative of the gauge-invariant quantity Tr ln D(q), which we interpret as the gauge-boson `self-loop'. By considering the higher-order corrections to this quantity, we are able to obtain a Gribov equation which sums the logarithmically enhanced corrections. By solving this equation, we obtain the non-perturbative running coupling in both QCD and QED. In the case of QCD, alpha_S has a singularity in the space-like region corresponding to super-criticality, which is argued to be resolved in Gribov's light-quark confinement scenario. For the QED coupling in the UV limit, we obtain a \propto Q^2 behaviour for space-like Q^2=-q^2. This implies the decoupling of the photon and an NJLVL-type effective theory in the UV limit.Comment: 12 pages, 5 figures; version to be published in Eur. Phys. J.

    Primordial nucleosynthesis and hadronic decay of a massive particle with a relatively short lifetime

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    In this paper we consider the effects on big bang nucleosynthesis (BBN) of the hadronic decay of a long-lived massive particle. If high-energy hadrons are emitted near the BBN epoch (t102t \sim 10^{-2} -- 102sec10^2 \sec), they extraordinarily inter-convert the background nucleons each other even after the freeze-out time of the neutron to proton ratio. Then, produced light element abundances are changed, and that may result in a significant discrepancy between standard BBN and observations. Especially on the theoretical side, now we can obtain a lot of experimental data of hadrons and simulate the hadronic decay process executing the numerical code of the hadron fragmentation even in the high energy region where we have no experimental data. Using the light element abundances computed in the hadron-injection scenario, we derive a constraint on properties of such a particle by comparing our theoretical results with observations.Comment: 33 pages, 14 postscript figures, reference added, typo corrected, to appear in Phys. Rev.

    Immunoglobulin free light chains are biomarkers of poor prognosis in basal-like breast cancer and are potential targets in tumor-associated inflammation

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    Inflammation is an important component of various cancers and its inflammatory cells and mediators have been shown to have prognostic potential. Tumor-infiltrating mast cells can promote tumor growth and angiogenesis, but the mechanism of mast cell activation is unclear. In earlier studies, we demonstrated that immunoglobulin free light chains (FLC) can trigger mast cells in an antigen-specific manner. Increased expression of FLC was observed within stroma of various human cancers including those of breast, colon, lung, pancreas, kidney and skin, and FLC expression co-localized with areas of mast cell infiltration. In a large cohort of breast cancer patients, FLC expression was shown associated with basal-like cancers with an aggressive phenotype. Moreover, lambda FLC was found expressed in areas of inflammatory infiltration and its expression was significantly associated with poor clinical outcome. Functional importance of FLCs was shown in a murine B16F10 melanoma model, where inhibition of FLC-mediated mast cell activation strongly reduced tumor growth. Collectively, this study identifies FLCs as a ligand in the pro-tumorigenic activation of mast cells. Blocking this pathway may open new avenues for the inhibition of tumor growth, while immunohistochemical staining of FLC may be helpful in the diagnosis and prognosis of cancer

    Spiral Multi-component Structure in Pade - Approximant QCD

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    We present a graphical method of analyzing the infra-red fixed point structure of Pade approximant QCD. The analysis shows a spiral multi-component couplant structure as well as an infra-red attractor behavior of PQCD couplant for all flavors 0Nf160 \le N_{f} \le 16.Comment: 78 pages, 4 tables, 44 graph

    Scale setting for alpha_s beyond leading order

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    We present a general procedure for incorporating higher-order information into the scale-setting prescription of Brodsky, Lepage and Mackenzie. In particular, we show how to apply this prescription when the leading coefficient or coefficients in a series in the strong coupling alpha_s are anomalously small and the original prescription can give an unphysical scale. We give a general method for computing an optimum scale numerically, within dimensional regularization, and in cases when the coefficients of a series are known. We apply it to the heavy quark mass and energy renormalization in lattice NRQCD, and to a variety of known series. Among the latter, we find significant corrections to the scales for the ratio of e+e- to hadrons over muons, the ratio of the quark pole to MSbar mass, the semi-leptonic B-meson decay width, and the top decay width. Scales for the latter two decay widths, expressed in terms of MSbar masses, increase by factors of five and thirteen, respectively, substantially reducing the size of radiative corrections.Comment: 39 pages, 15 figures, 5 tables, LaTeX2

    Updated Nucleosynthesis Constraints on Unstable Relic Particles

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    We revisit the upper limits on the abundance of unstable massive relic particles provided by the success of Big-Bang Nucleosynthesis calculations. We use the cosmic microwave background data to constrain the baryon-to-photon ratio, and incorporate an extensively updated compilation of cross sections into a new calculation of the network of reactions induced by electromagnetic showers that create and destroy the light elements deuterium, he3, he4, li6 and li7. We derive analytic approximations that complement and check the full numerical calculations. Considerations of the abundances of he4 and li6 exclude exceptional regions of parameter space that would otherwise have been permitted by deuterium alone. We illustrate our results by applying them to massive gravitinos. If they weigh ~100 GeV, their primordial abundance should have been below about 10^{-13} of the total entropy. This would imply an upper limit on the reheating temperature of a few times 10^7 GeV, which could be a potential difficulty for some models of inflation. We discuss possible ways of evading this problem.Comment: 40 pages LaTeX, 18 eps figure

    Charm-anticharm baryon production asymmetries in photon-nucleon interactions

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    We report measurements of the charm-anticharm production asymmetries for Λc+\Lambda_c^+, Σc++\Sigma_c^{++}, Σc0\Sigma_c^0, Σc++\Sigma_c^{++*}, Σc0\Sigma_c^{0*}, and Λc+(2625)\Lambda_c^+(2625) baryons from the Fermilab photoproduction experiment FOCUS (E831). These asymmetries are integrated over the region where the spectrometer has good acceptance. In addition, we have obtained results for the photoproduction asymmetries of the Λc\Lambda_c baryons as functions of pLp_L, pT2p_T^2, and xFx_F. The integrated asymmetry for Λc+\Lambda_c^+ production, (σΛc+σΛc)/(σΛc++σΛc)(\sigma_{\Lambda_c^+} - \sigma_{\Lambda_c^-}) / (\sigma_{\Lambda_c^+} + \sigma_{\Lambda_c^-}), is 0.111±0.018±0.0120.111 \pm 0.018 \pm 0.012, significantly different from zero. The asymmetries of the excited states are consistent with the Λc\Lambda_c asymmetry.Comment: 12 pages, 9 figures, 1 tabl
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