82 research outputs found

    A domain decomposition method for approximating the conformal modules of long quadrilaterals

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    This paper is concerned with the study of a domain decomposition method for approximating the conformal modules of long quadrilaterals. The method has been studied already by us and also by D Gaier and W K Hayman, but only in connection with a special class of quadrilaterals, viz. quadrilaterals where: (a) the defining domain is bounded by two parallel straight lines and two Jordan arcs, and (b) the four specified boundary points are the four corners where the arcs meet the straight lines. Our main purpose here is to explain how the method may be extended to a wider class of qua-drilaterals than that indicated above

    Finite Number and Finite Size Effects in Relativistic Bose-Einstein Condensation

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    Bose-Einstein condensation of a relativistic ideal Bose gas in a rectangular cavity is studied. Finite size corrections to the critical temperature are obtained by the heat kernel method. Using zeta-function regularization of one-loop effective potential, lower dimensional critical temperatures are calculated. In the presence of strong anisotropy, the condensation is shown to occur in multisteps. The criteria of this behavior is that critical temperatures corresponding to lower dimensional systems are smaller than the three dimensional critical temperature.Comment: 18 pages, 9 figures, Fig.3 replaced, to appear in Physical Review

    O(N) Quantum fields in curved spacetime

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    For the O(N) field theory with lambda Phi^4 self-coupling, we construct the two-particle-irreducible (2PI), closed-time-path (CTP) effective action in a general curved spacetime. From this we derive a set of coupled equations for the mean field and the variance. They are useful for studying the nonperturbative, nonequilibrium dynamics of a quantum field when full back reactions of the quantum field on the curved spacetime, as well as the fluctuations on the mean field, are required. Applications to phase transitions in the early Universe such as the Planck scale or in the reheating phase of chaotic inflation are under investigation.Comment: 31 pages, 2 figures, uses RevTeX 3.1, LaTeX 2e, AMSfonts 2.2, graphics 0.6; To appear in Phys. Rev. D (7/15/97

    Hypertonicity counteracts MCL 1 and renders BCL XL a synthetic lethal target in head and neck cancer

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    Head and neck squamous cell carcinoma (HNSCC) is an aggressive and difficult‐to‐treat cancer entity. Current therapies ultimately aim to activate the mitochondria‐controlled (intrinsic) apoptosis pathway, but complex alterations in intracellular signaling cascades and the extracellular microenvironment hamper treatment response. On the one hand, proteins of the BCL‐2 family set the threshold for cell death induction and prevent accidental cellular suicide. On the other hand, controlling a cell's readiness to die also determines whether malignant cells are sensitive or resistant to anticancer treatments. Here, we show that HNSCC cells upregulate the proapoptotic BH3‐only protein NOXA in response to hyperosmotic stress. Induction of NOXA is sufficient to counteract the antiapoptotic properties of MCL‐1 and switches HNSCC cells from dual BCL‐XL/MCL‐1 protection to exclusive BCL‐XL addiction. Hypertonicity‐induced functional loss of MCL‐1 renders BCL‐XL a synthetically lethal target in HNSCC, and inhibition of BCL‐XL efficiently kills HNSCC cells that poorly respond to conventional therapies. We identify hypertonicity‐induced upregulation of NOXA as link between osmotic pressure in the tumor environment and mitochondrial priming, which could perspectively be exploited to boost efficacy of anticancer drugs

    Approximation of Conformal Mappings 1 Approximation of Conformal Mappings of Annular Regions y

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    In this paper we examine the convergence rates in an adaptive version of an orthonormalization method for approximating the conformal mapping f of an annular region A onto a circular annulus. In particular, we consider the case where f has an analytic extension in compl(A) and,for this case, we determine optimal ray sequences of approximants that give the best possible geometric rate of uniform convergence. We also estimate the rate of uniform convergence in the case where the annular region A has piecewise analytic boundary without cusps. In both cases we also give the corresponding rates for the approximations to the conformal module of A. AMS classi cation: 30C30, 65E05, 41A20

    Molecular characterization of Campylobacter spp. recovered from beef, chicken, lamb and pork products at retail in Australia

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    Australian rates of campylobacteriosis are among the highest in developed countries, yet only limited work has been done to characterize Campylobacter spp. in Australian retail products. We performed whole genome sequencing (WGS) on 331 C. coli and 285 C. jejuni from retail chicken meat, as well as beef, chicken, lamb and pork offal (organs). Campylobacter isolates were highly diverse, with 113 sequence types (STs) including 38 novel STs, identified from 616 isolates. Genomic analysis suggests very low levels (2.3-15.3%) of resistance to aminoglycoside, beta-lactam, fluoroquinolone, macrolide and tetracycline antibiotics. A majority (>90%) of isolates (52/56) possessing the fluoroquinolone resistance-associated T86I mutation in the gyrA gene belonged to ST860, ST2083 or ST7323. The 44 pork offal isolates were highly diverse, representing 33 STs (11 novel STs) and harboured genes associated with resistance to aminoglycosides, lincosamides and macrolides not generally found in isolates from other sources. Prevalence of multidrug resistant genotypes was very low (<5%), but ten-fold higher in C. coli than C. jejuni. This study highlights that Campylobacter spp. from retail products in Australia are highly genotypically diverse and important differences in antimicrobial resistance exist between Campylobacter species and animal sources
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