8,409 research outputs found

    [Review of] Bill Ong Hing. Making and Remaking Asian America Through Immigration Policy

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    Bill Ong Hing\u27s book has fulfilled a long-felt need in Asian American studies. Since the publication of Milton R. Konvitz\u27s The Alien and Asiatic in American Law (1946), no comprehensive overview of how American immigration policy influenced Asian immigration has been published. The subject, however, represents one of the most important aspects of Asian American experience. Historically, the anti-Asiatic Exclusion Laws played a defining role in the evolution of Asian America. Today, the legacy of racist immigration policies continue to limit Asian Americans, and the current debate over immigration remains an issue of great importance for the communities

    Next-to-leading order QCD corrections to the single top quark production via model-independent t-q-g flavor-changing neutral-current couplings at hadron colliders

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    We present the calculations of the complete next-to-leading order (NLO) QCD effects on the single top productions induced by model-independent tqgtqg flavor-changing neutral-current couplings at hadron colliders. Our results show that, for the tcgtcg coupling the NLO QCD corrections can enhance the total cross sections by about 60% and 30%, and for the tugtug coupling by about 50% and 20% at the Tevatron and LHC, respectively, which means that the NLO corrections can increase the experimental sensitivity to the FCNC couplings by about 10%−-30%. Moreover, the NLO corrections reduce the dependence of the total cross sections on the renormalization or factorization scale significantly, which lead to increased confidence on the theoretical predictions. Besides, we also evaluate the NLO corrections to several important kinematic distributions, and find that for most of them the NLO corrections are almost the same and do not change the shape of the distributions.Comment: minor changes, version published in PR

    Associated production of the top-pions and single top at hadron colliders

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    In the context of topcolor assisted technicolor(TC2) models, we study the production of the top-pions πt0,±\pi_{t}^{0,\pm} with single top quark via the processes ppˉ→tπt0+Xp\bar{p} \to t\pi_{t}^{0}+X and ppˉ→tπt±+Xp\bar{p} \to t\pi_{t}^{\pm}+X, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions πt0\pi_{t}^{0} and πt±\pi_{t}^{\pm} can be detecting via considering the same sign top pair ttcˉtt\bar{c} event and the ttbˉtt\bar{b} (or ttˉbt\bar{t}b) event at LHC, respectively.Comment: latex files,14 pages, 7 figures. Accepted for publication in Phys. Rev.

    Coupled Reversible and Irreversible Bistable Switches Underlying TGF-\beta-induced Epithelial to Mesenchymal Transition

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    Epithelial to mesenchymal transition (EMT) plays important roles in embryonic development, tissue regeneration and cancer metastasis. While several feedback loops have been shown to regulate EMT, it remains elusive how they coordinately modulate EMT response to TGF-\beta treatment. We construct a mathematical model for the core regulatory network controlling TGF-\beta-induced EMT. Through deterministic analyses and stochastic simulations, we show that EMT is a sequential two-step program that an epithelial cell first transits to partial EMT then to the mesenchymal state, depending on the strength and duration of TGF-\beta stimulation. Mechanistically the system is governed by coupled reversible and irreversible bistable switches. The SNAIL1/miR-34 double negative feedback loop is responsible for the reversible switch and regulates the initiation of EMT, while the ZEB/miR-200 feedback loop is accountable for the irreversible switch and controls the establishment of the mesenchymal state. Furthermore, an autocrine TGF-\beta/miR-200 feedback loop makes the second switch irreversible, modulating the maintenance of EMT. Such coupled bistable switches are robust to parameter variation and molecular noise. We provide a mechanistic explanation on multiple experimental observations. The model makes several explicit predictions on hysteretic dynamic behaviors, system response to pulsed stimulation and various perturbations, which can be straightforwardly tested.Comment: 32 pages, 8 figures, accepted by Biophysical Journa

    Diphoton excess at 750 GeV: gluon-gluon fusion or quark-antiquark annihilation?

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    Recently, ATLAS and CMS collaboration reported an excess in the diphoton events, which can be explained by a new resonance with mass around 750 GeV. In this work, we explored the possibility of identifying if the hypothetical new resonance is produced through gluon-gluon fusion or quark-antiquark annihilation, or tagging the beam. Three different observables for beam tagging, namely the rapidity and transverse momentum distribution of the diphoton, and one tagged bottom-jet cross section, are proposed. Combining the information gained from these observables, a clear distinction of the production mechanism for the diphoton resonance is promising.Comment: 20 pages, 7 figure
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