6,510 research outputs found

    Alpha_s and Gauge Coupling Unification in Flipped SU(5) Models with Gauge-Mediated Supersymmetry Breaking

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    We examine gauge coupling unification and prediction for αs(MZ)\alpha_s (M_Z) in minimal flipped SU(5) with gauge-mediated supersymmetry breaking. We include threshold corrections at weak scale, messenger scale and unification scale, and explicitly show that in this model there can be either \emph{one-step} or \emph{two-step} gauge coupling unification, depending on unification-scale threshold corrections. The experimental value of αs(MZ)\alpha_s (M_Z) constrains heavy particle masses in one-step unification. In the case of two-step unification, we examine the prediction for αs(MZ)\alpha_s (M_Z) with two-loop, light, messenger and heavy threshold corrections, and find it to be compatible with the updated experimental data.Comment: 12 pages including 3 figures, LaTeX; a few comments added; to appear in Phys. Lett.

    Probing nucleon strangeness structure with phi electroproduction

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    We study the possibility to constrain the hidden strangeness content of the nucleon by means of the polarization observables in phi meson electroproduction. We consider the OZI evading direct knockout mechanism that arises from the non-vanishing s\bar{s} sea quark admixture of the nucleon as well as the background of the dominant diffractive and the one-boson-exchange processes. Large sensitivity on the nucleon strangeness are found in several beam-target and beam-recoil double polarization observables. The small \sqrt{s} and W region, which is accesible at some of the current high-energy electron facilities, is found to be the optimal energy region for extracting out the OZI evasion process.Comment: 8 pages, LaTeX2e, elsart.cls, 3 figures (4 eps files

    Hadronic Probes of the Polarized Intrinsic Strangeness of the Nucleon

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    We have previously interpreted the various large apparent violations of the naive Okubo-Zweig-Iizuka (OZI) rule found in many channels in pˉp\bar{p}p annihilation at LEAR as evidence for an intrinsic polarized sˉs\bar{s}s component of the nucleon wave function. The model is further supported by new data from LEAR and elsewhere. Here we discuss in more detail the possible form of the sˉs\bar{s}s component of the nucleon wave function, interpret the new data and clarify the relative roles of strangeness shake-out and rearrangement, discuss whether alternative interpretations are still allowed by the new data, and propose more tests of the model.Comment: LaTeX, 31 page

    Experimental constraints on the parameter space of the next-to-minimal supersymmetric standard model at LEP 2

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    We search for the neutral Higgs sector of the next-to-minimal supersymmetric standard model at LEP 2. At the tree level any experimental constraints on tanβ\tan \beta cannot be set by the Higgs search at LEP 2 with s\sqrt{s} = 175 GeV, whereas at LEP 2 with s\sqrt{s} = 192 GeV tanβ\tan \beta can be set by an experimental constraint. Furthermore the tree level parameter space of the model can be completely explored by the Higgs search at LEP 2 with s\sqrt{s} = 205 GeV. Radiative corrections both to the neutral Higgs boson masses and to the relevant couplings for the scalar Higgs productions give large contributions to the production cross sections of the scalar Higgs bosons at the tree level. The tree level situation at LEP 2 with s\sqrt{s} = 192 GeV as well as with s\sqrt{s} = 205 GeV can be drastically changed by these effects. We expect that a small region of the 1-loop level parameter space of the model via the scalar Higgs production can be explored by the Higgs search at LEP 2.Comment: 14 pages (3 figures are included

    Eupatilin Inhibits Gastric Cancer Cell Growth by Blocking STAT3-Mediated VEGF Expression

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    Purpose: Eupatilin is an antioxidative flavone and a phytopharmaceutical derived from Artemisia asiatica. It has been reported to possess anti-tumor activity in some types of cancer including gastric cancer. Eupatilin may modulate the angiogenesis pathway which is part of anti-inflammatory effect demonstrated in gastric mucosal injury models. Here we investigated the anti-tumor effects of eupatilin on gastric cancer cells and elucidated the potential underlying mechanism whereby eupatilin suppresses angiogenesis and tumor growth. Materials and Methods: The impact of eupatilin on the expression of angiogenesis pathway proteins was assessed using western blots in MKN45 cells. Using a chromatin immunoprecipitation assay, we tested whether eupatilin affects the recruitment of signal transducer and activator of transcription 3 (STAT3), aryl hydrocarbon receptor nuclear translocator (ARNT) and hypoxia-inducible factor- (HIF-) to the human VEGF promoter. To investigate the effect of eupatilin on vasculogenesis, tube formation assays were conducted using human umbilical vein endothelial cells (HUVECs). The effect of eupatilin on tumor suppression in mouse xenografts was assessed. Results: Eupatilin significantly reduced VEGF, ARNT and STAT3 expression prominently under hypoxic conditions. The recruitment of STAT3, ARNT and HIF- to the VEGF promoter was inhibited by eupatilin treatment. HUVECs produced much foreshortened and severely broken tubes with eupatilin treatment. In addition, eupatilin effectively reduced tumor growth in a mouse xenograft model. Conclusions: Our results indicate that eupatilin inhibits angiogenesis in gastric cancer cells by blocking STAT3 and VEGF expression, suggesting its therapeutic potential in the treatment of gastric cancer.ope

    The University of Minnesota pathway prediction system: predicting metabolic logic

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    The University of Minnesota pathway prediction system (UM-PPS, http://umbbd.msi.umn.edu/predict/) recognizes functional groups in organic compounds that are potential targets of microbial catabolic reactions, and predicts transformations of these groups based on biotransformation rules. Rules are based on the University of Minnesota biocatalysis/biodegradation database (http://umbbd.msi.umn.edu/) and the scientific literature. As rules were added to the UM-PPS, more of them were triggered at each prediction step. The resulting combinatorial explosion is being addressed in four ways. Biodegradation experts give each rule an aerobic likelihood value of Very Likely, Likely, Neutral, Unlikely or Very Unlikely. Users now can choose whether they view all, or only the more aerobically likely, predicted transformations. Relative reasoning, allowing triggering of some rules to inhibit triggering of others, was implemented. Rules were initially assigned to individual chemical reactions. In selected cases, these have been replaced by super rules, which include two or more contiguous reactions that form a small pathway of their own. Rules are continually modified to improve the prediction accuracy; increasing rule stringency can improve predictions and reduce extraneous choices. The UM-PPS is freely available to all without registration. Its value to the scientific community, for academic, industrial and government use, is good and will only increase

    A K-theory Anomaly Free Supersymmetric Flipped SU(5) Model from Intersecting Branes

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    We construct an N=1 supersymmetric three-family flipped SU(5) model from type IIA orientifolds on T6/(Z2×Z2)T^6/(\Z_2\times \Z_2) with D6-branes intersecting at general angles. The model is constrained by the requirement that Ramond-Ramond tadpoles cancel, the supersymmetry conditions, and that the gauge boson coupled to the U(1)XU(1)_X factor does not get a string-scale mass via a generalised Green-Schwarz mechanism. The model is further constrained by requiring cancellation of K-theory charges. The spectrum contains a complete grand unified and electroweak Higgs sector, however the latter in a non-minimal number of copies. In addition, it contains extra matter both in bi-fundamental and vector-like representations as well as two copies of matter in the symmetric representation of SU(5).Comment: 17 Pages, LaTe

    A rodent model of HIV protease inhibitor indinavir induced peripheral neuropathy

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    The research leading to these results is part of the EUROPAIN Collaboration, which has received support from the Innovative Medicines Initiative Joint Undertaking, under grant agreement no 115007, resources of which are composed of financial contribution from the European Union's Seventh Framework Program (FP7/2007‐2013) and EFPIA companies’ in kind contribution. We thank Pfizer for providing indinavir and gabapentin. MC received Conicyt grant (Folio 82130016),to complete this work.Peer reviewedPostprin

    Absolute Upper Bound on the 1-loop Corrected mass of S1S_1 in the NMSSM

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    We examine in detail radiative corrections to the lightest scalar Higgs boson mass due to the top quark and scalar quark loops in the next-to-minimal supersymmetric standard model (NMSSM). We take into account the nondegenerate state for the top scalar quark masses. In our analysis, the mass matrix of the top scalar quark contains the gauge terms. Therefore our formula for the scalar Higgs boson mass matrix at the 1-loop level includes the contribution of the gauge sector as well as the effect of the top scalar quark mass splitting. Thus we calculate the upper bound on the lightest scalar Higgs boson mass using our formula. We find that the absolute upper bound on the 1-loop corrected mass of the lightest scalar Higgs boson is about 156 GeV.Comment: 12 pages(Latex), 6 Postscript figures are included Figur
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