101 research outputs found

    Using Heavy Quark Spin Symmetry in Semileptonic BcB_c Decays

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    The form factors parameterizing the B_c semileptonic matrix elements can be related to a few invariant functions if the decoupling of the spin of the heavy quarks in B_c and in the mesons produced in the semileptonic decays is exploited. We compute the form factors as overlap integral of the meson wave-functions obtained using a QCD relativistic potential model, and give predictions for semileptonic and non-leptonic B_c decay modes. We also discuss possible experimental tests of the heavy quark spin symmetry in B_c decays.Comment: RevTex, 22 pages, 2 figure

    Sensorimotor impairments of paretic upper limb correlates with activities of daily living in subjects with chronic stroke

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    The  main objective  of  this  study  was  to  investigate  the correlations  between sensorimotor  impairments  of  paretic  upper  limb  and the  hand  functions of  activities of daily  living  (ADLs)  scores  in  persons  with chronic stroke.This is a cross-sectional  study  with  19  chronic  stroke  survivors.  Hand function was measured by the Jebsen-Taylor Hand Function Test (JTHFT). Impairments in upper extremity motor function were measured by upper limb items  of  Fugl-Meyer  Assessment  (FMA-UE).  Forearm  muscles  strength, handgrip  and  pinch  grip  power  were  assessed  using  handheld  dynamo-meters. Tactile sensation threshold was measured by monofilaments.Significant differences were found between the affected and unaffected side in the total JTHFT scores, forearm muscle strength, handgrip and pinch grip (p≤0.017), but not the tactile sensa-tion threshold.  The total JTHFT scores were found to be correlated with total score of FMA-UE (rs = -0.789), hand-grip  power  (rs = -0.588) and pinch grip power (rs = -0.657) on the affected side, but not the tactile sensation. The total JTHFT scores were correlated with FMA-UE scores, handgrip and pinch grip of the affected side.  This is the first study in documenting the correlation between the sensorimotor impairments and JTHFT scores in persons with  chronic stroke. Our findings highlights the importance of including upper limb and grip strength training in stroke rehabilitation program in order to improve hand functions in activities of daily living in patients with chronic stroke

    Aspects of Two-Photon Physics at Linear e+e- Colliders

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    We discuss various reactions at future e+e- and gamma-gamma colliders involving real (beamstrahlung or backscattered laser) or quasi--real (bremsstrahlung) photons in the initial state and hadrons in the final state. The production of two central jets with large pT is described in some detail; we give distributions for the rapidity and pT of the jets as well as the di--jet invariant mass, and discuss the relative importance of various initial state configurations and the uncertainties in our predictions. We also present results for `mono--jet' production where one jet goes down a beam pipe, for the production of charm, bottom and top quarks, and for single production of W and Z bosons. Where appropriate, the two--photon processes are compared with annihilation reactions leading to similar final states. We also argue that the behaviour of the total inelastic gamma-gamma cross section at high energies will probably have little impact on the severity of background problems caused by soft and semi--hard (`minijet') two--photon reactions. We find very large differences in cross sections for all two--photon processes between existing designs for future e+e- colliders, due to the different beamstrahlung spectra; in particular, both designs with >1 events per bunch crossing exist.Comment: 51 pages, 13 figures(not included

    A Phenomenological Analysis of Gluon Mass Effects in Inclusive Radiative Decays of the J/ψ\rm{J/\psi} and $\Upsilon

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    The shapes of the inclusive photon spectra in the processes \Jp \to \gamma X and \Up \to \gamma X have been analysed using all available experimental data. Relativistic, higher order QCD and gluon mass corrections were taken into account in the fitted functions. Only on including the gluon mass corrections, were consistent and acceptable fits obtained. Values of 0.7210.068+0.0160.721^{+0.016}_{-0.068} GeV and 1.180.29+0.091.18^{+0.09}_{-0.29} GeV were found for the effective gluon masses (corresponding to Born level diagrams) for the \Jp and \Up respectively. The width ratios \Gamma(V \to {\rm hadrons})/\Gamma(V \to \gamma+ {\rm hadrons}) V=\Jp, \Up were used to determine αs(1.5GeV)\alpha_s(1.5 {\rm GeV}) and αs(4.9GeV)\alpha_s(4.9 {\rm GeV}). Values consistent with the current world average αs\alpha_s were obtained only when gluon mass correction factors, calculated using the fitted values of the effective gluon mass, were applied. A gluon mass 1\simeq 1 GeV, as suggested with these results, is consistent with previous analytical theoretical calculations and independent phenomenological estimates, as well as with a recent, more accurate, lattice calculation of the gluon propagator in the infra-red region.Comment: 50 pages, 11 figures, 15 table

    Dependence of the emission from tris(8-hydroxyquinoline) aluminum based microcavity on device thickness and the emission layer position

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    In this work, we present a systematic study of the emission from bilayer organic microcavity light emitting diodes with two metal mirrors. The devices consisting of two organic layers, N,NV-di(naphthalene-1-yl)-N,NV-diphenylbenzidine as the hole transport layer and tris (8-hydroxyquinoline) aluminum as the emitting layer, and two metal mirrors were fabricated and characterized by transmittance, reflectance, photoluminescence, and electroluminescence measurements. The effects of layer thickness, interface position, and the choice of anode(bottom mirror) were investigated. The transmittance and reflectance spectra were modeled using a transfer matrix model, and the optical functions for all the materials used were determined by spectroscopic ellipsometry. The dependence of the photoluminescence and electroluminescence spectra on the device thickness and interface position is discussed

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    Measurement of \chi_{c2} Production in Two-Photon Collisions

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    The production of the \chi_{c2} charmonium state in two-photon collisions has been measured with the Belle detector at the KEKB e^+e^- collider. A clear signal for \chi_{c2} --> \gamma J/\psi, J/\psi --> l^+l^- is observed in a 32.6fb^{-1} data sample accumulated at center-of-mass energies near 10.6GeV, and the product of its two-photon decay width and branching fraction is determined to be \Gamma_{\gamma\gamma}(\chi_{c2})B(\chi_{c2} --> \gamma J/\psi) B(J/\psi --> l^+l^-)= 13.5 +/- 1.3(stat.) +/- 1.1(syst.)eV.Comment: 16 pages, 5 figures, to be submitted to Phys. Lett.

    Oncogenic Signaling Pathways in The Cancer Genome Atlas

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    Genetic alterations in signaling pathways that control cell-cycle progression, apoptosis, and cell growth are common hallmarks of cancer, but the extent, mechanisms, and co-occurrence of alterations in these pathways differ between individual tumors and tumor types. Using mutations, copy-number changes, mRNA expression, gene fusions and DNA methylation in 9,125 tumors profiled by The Cancer Genome Atlas (TCGA), we analyzed the mechanisms and patterns of somatic alterations in ten canonical pathways: cell cycle, Hippo, Myc, Notch, Nrf2, PI-3-Kinase/Akt, RTK-RAS, TGFb signaling, p53 and beta-catenin/Wnt. We charted the detailed landscape of pathway alterations in 33 cancer types, stratified into 64 subtypes, and identified patterns of co-occurrence and mutual exclusivity. Eighty-nine percent of tumors had at least one driver alteration in these one alteration potentially targetable by currently available drugs. Thirty percent of tumors had multiple targetable alterations, indicating opportunities for combination therapy

    Measurement of ηc production in untagged two-photon collisions at LEP

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    RE-MADE (IN) HONG KONG: Co-(Shop)housing: People's alternative approach to redevelop Tin Shui Wai New Town

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    In the future scenario 5 years from now, the Hong Kong government decided to help gentrify the whole Hong Kong cities, so decided to demolish all the public housing in Hong Kong and relocate the underprivileged people to “Hong Kong Land” in Mainland China. Tin Shui Wai New Town will be developed once again trying to get rid of the negative image with the gentrification approach of the government to private housing estates. The Right to the City is questioned. Who own the city? Who has the right to the city? In the process of demolition of Tin Shui Wai, protestors occupy the deconstruction site and start their own version of redevelopment. People should be protected to live in their original living place. People should have the right to make decision on their living environment. This project touches on a lot of important aspects happening in Hong Kong, including urban renewal, resident’s right to the land, resettlement, self-building, etc. What is the people’s approach to redevelopment? How to empower the people? A people’s version of redevelopment will be the centre of the project. This is a housing project, by researching the transformation of housing typology in Hong Kong and co-housing projects in Europe. A new typology, Co-(Shop)housing is developed. By combining the characteristics of the South-east Asian Shophouse typology and that of the cohousing neighborhood typology, a new housing typology which fits the culture with the introduction of community decision making in the building and maintainence process is being introduced.Design as PoliticsArchitectureArchitecture and The Built Environmen
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