147 research outputs found

    Examination of Carotid Arteries with Quantitative Color Doppler Flow Imaging

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    The results of conventional duplex scanning were compared with QCDFI. A total of 224 consecutive patients comprising 442 unilateral carotid systems were examined by conventional duplex techniques. MPSV, as determined by QCDFI, were recorded for each of the 442 carotid segments and grouped according to the previously determined degrees of stenosis. The predictive value of QCDFI was confirmed by angiography with an overall accuracy of 91%. Results obtained by duplex scanning correlated with angiography 89% of the time. Based on QCDFI data, a scale to grade carotid stenosis was developed

    Mixing of scalar glueballs and flavour-singlet scalar mesons

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    We discuss in detail the extraction of hadronic mixing strengths from lattice studies. We apply this to the mixing of a scalar glueball and a scalar meson in the quenched approximation. We also measure correlations appropriate for flavour-singlet scalar mesons using dynamical quark configurations from UKQCD. This enables us to compare the results from the quenched study of the mixing with the direct determination of the mixed spectrum. Improved methods of evaluating the disconnected quark diagrams are also presented.Comment: 23 pages, 5 postscript figure

    Quantum Symmetries and Strong Haagerup Inequalities

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    In this paper, we consider families of operators {xr}rΛ\{x_r\}_{r \in \Lambda} in a tracial C^\ast-probability space (A,ϕ)(\mathcal A, \phi), whose joint \ast-distribution is invariant under free complexification and the action of the hyperoctahedral quantum groups {Hn+}nN\{H_n^+\}_{n \in \N}. We prove a strong form of Haagerup's inequality for the non-self-adjoint operator algebra B\mathcal B generated by {xr}rΛ\{x_r\}_{r \in \Lambda}, which generalizes the strong Haagerup inequalities for \ast-free R-diagonal families obtained by Kemp-Speicher \cite{KeSp}. As an application of our result, we show that B\mathcal B always has the metric approximation property (MAP). We also apply our techniques to study the reduced C^\ast-algebra of the free unitary quantum group Un+U_n^+. We show that the non-self-adjoint subalgebra Bn\mathcal B_n generated by the matrix elements of the fundamental corepresentation of Un+U_n^+ has the MAP. Additionally, we prove a strong Haagerup inequality for Bn\mathcal B_n, which improves on the estimates given by Vergnioux's property RD \cite{Ve}

    Exotic Non-Supersymmetric Gauge Dynamics from Supersymmetric QCD

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    We extend Seiberg's qualitative picture of the behavior of supersymmetric QCD to nonsupersymmetric models by adding soft supersymmetry breaking terms. In this way, we recover the standard vacuum of QCD with NfN_f flavors and NcN_c colors when Nf<NcN_f < N_c. However, for NfNcN_f \geq N_c, we find new exotic states---new vacua with spontaneously broken baryon number for Nf=NcN_f = N_c, and a vacuum state with unbroken chiral symmetry for Nf>NcN_f > N_c. These exotic vacua contain massless composite fermions and, in some cases, dynamically generated gauge bosons. In particular Seiberg's electric-magnetic duality seems to persist also in the presence of (small) soft supersymmetry breaking. We argue that certain, specially tailored, lattice simulations may be able to detect the novel phenomena. Most of the exotic behavior does not survive the decoupling limit of large SUSY breaking parameters.Comment: 36 pages, latex + 2 figures (uuencoded ps

    Retroperitoneal Castleman’s disease: advocating a multidisciplinary approach for a rare clinical entity

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    BACKGROUND: Castleman’s disease is a rare and poorly understood disease entity that may resemble more common conditions and represents a clinical challenge to the treating surgeon. CASE PRESENTATION: In this report, we describe a case of a 61-year-old Caucasian woman with a symptomatic retroperitoneal mass. The specimen obtained from her resection contained a protuberant encapsulated mass, exhibiting microscopic features consistent with localized, unicentric Castleman’s disease. These characteristics included architectural features and immunohistochemical findings consistent with the hyaline vascular variant of Castleman’s disease. CONCLUSION: We report a very rare case of a retroperitoneal hyaline vascular type of Castleman’s disease. We discuss the diagnostic dilemma Castleman’s disease may present to the surgeon, with an emphasis on multidisciplinary management of these patients. We also review current data on pathogenesis, treatment and outcomes

    Pathologies of Quenched Lattice QCD at non--zero Density and its Effective Potential

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    We simulate lattice QCD at non--zero baryon density and zero temperature in the quenched approximation, both in the scaling region and in the infinite coupling limit. We investigate the nature of the forbidden region -- the range of chemical potential where the simulations grow prohibitively expensive, and the results, when available, are puzzling if not unphysical. At weak coupling we have explored the sensitivity of these pathologies to the lattice size, and found that using a large lattice (64×16364 \times 16^3) does not remove them. The effective potential sheds considerable light on the problems in the simulations, and gives a clear interpretation of the forbidden region. The strong coupling simulations were particularly illuminating on this point.Comment: 49 pages, uu-encoded expanding to postscript;also available at ftp://hlrz36.hlrz.kfa-juelich.de/pub/mpl/hlrz72_95.p

    Gene expression changes in therapeutic ultrasound-treated venous leg ulcers

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    IntroductionLow-frequency, low-intensity ultrasound has been previously shown to promote healing of chronic wounds in humans, but mechanisms behind these effects are poorly understood. The purpose of this study was to evaluate gene expression differences in debrided human venous ulcer tissue from patients treated with low-frequency (20 kHz), low-intensity (100 mW/cm2) ultrasound compared to a sham treatment in an effort to better understand the potential biological mechanisms.MethodsDebrided venous ulcer tissue was collected from 32 subjects one week after sham treatment or low-frequency, low-intensity ultrasound treatment. Of these samples, 7 samples (3 ultrasound treated and 4 sham treated) yielded sufficient quality total RNA for analysis by ultra-high multiplexed PCR (Ampliseq) and expression of more than 24,000 genes was analyzed. 477 genes were found to be significantly differentially expressed between the ultrasound and sham groups using cut-off values of p &lt; 0.05 and fold change of 2.Results and DiscussionThe top differentially expressed genes included those involved in regulation of cell metabolism, proliferation, and immune cell signaling. Gene set enrichment analysis identified 20 significantly enriched gene sets from upregulated genes and 4 significantly enriched gene sets from downregulated genes. Most of the enriched gene sets from upregulated genes were related to cell-cell signaling pathways. The most significantly enriched gene set from downregulated genes was the inflammatory response gene set. These findings show that therapeutic ultrasound influences cellular behavior in chronic wounds as early as 1 week after application. Considering the well-known role of chronic inflammation in impairing wound healing in chronic wounds, these results suggest that a downregulation of inflammatory genes is a possible biological mechanism of ultrasound-mediated venous chronic wound healing. Such increased understanding may ultimately lead to the enhancement of ultrasound devices to accelerate chronic wound healing and increase patient quality of life

    Glueball spectrum based on a rigorous three-dimensional relativistic equation for two-gluon bound states I: Derivation of the relativistic equation

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    A rigorous three-dimensional relativistic equation satisfied by two-gluon bound states is derived from the QCD with massive gluons. With the gluon fields and the quark fields being expanded in terms of the gluon multipole fields and the spherical Dirac spinors respectively, the equation is well established in the angular momentum representation and hence is much convenient for solving the problem of two-gluon glueball spectra. In particular, the interaction kernel in the equation is exactly derived and given a closed expression which includes all the interactions taking place in the two-gluon glueballs. The kernel contains only a few types of Green's functions and commutators. Therefore, it is not only easily calculated by the perturbation method, but also provides a suitable basis for nonperturbative investigations

    Glueball spectrum based on a rigorous three-dimensional relativistic equation for two-gluon bound states II: calculation of the glueball spectrum

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    In the preceding paper, a rigorous three-dimensional relativistic equation for two-gluon bound states was derived from the QCD with massive gluons and represented in the angular momentum representation. In order to apply this equation to calculate the glueball spectrum, in this paper, the equation is recast in an equivalent three-dimensional relativistic equation satisfied by the two-gluon positive energy state amplitude. The interaction Hamiltonian in the equation is exactly derived and expressed as a perturbative series. The first term in the series describes the one-gluon exchange interaction which includes fully the retardation effect in it. This term plus the linear confining potential are chosen to be the interaction Hamiltonian and employed in the practical calculation. With the integrals containing three and four spherical Bessel functions in the QCD vertices being analytically calculated, the interaction Hamiltonian is given an explicit expression in the angular momentum representation. Numerically solving the relativistic equation with taking the contributions arising from the retardation effect and the longitudinal mode of gluon fields into account, a set of masses for the 0++,0+,1++,1+,2++0^{++},0^{-+},1^{++},1^{-+},2^{++} and 2+2^{-+\text{}} glueball states are obtained and are in fairly good agreement with the predictions given by the lattice simulatio
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