393 research outputs found

    Methicillin-resistant Staphylococcus aureus isolated from various types of hospital infections in pediatrics: Panton-valentine leukocidin, staphylococcal chromosomal cassette mec SCCmec phenotypes and antibiotic resistance properties

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    Background: Staphylococcus aureus has long been considered as a major pathogen of hospital infections. Objectives: The present investigation was carried out to study the distribution of Staphylococcal Chromosomal Cassette mec (SCCmec) types, Panton-Valentine Leukocidin (PVL) gene and antibiotic resistance properties of Methicillin Resistant Staphylococcus aureus (MRSA) strains isolated from various types of infections found in Iranian pediatric patients. Patients and Methods: Two-hundred and fifty-five clinical specimens were collected from four major provinces of Iran. Samples were cultured and the MRSA strains were subjected to Polymerase Chain Reaction (PCR). The patterns of antibiotic resistance were determined using the disk diffusion method. Results: Seventy-four out of 255 (29.01) clinical samples were positive for MRSA. Of the 74 MRSA strains, 47 (63.51) were PVL positive. The clinical samples of respiratory tract infections (36.36), those from the Shiraz province (37.87) and samples collected during the summer season (56.48) were the most commonly infected samples. The most commonly detected antibiotic resistance genes were tetK (89.18), mecA (71.62), msrA (56.75) and tetM (54.05). Methicillin Resistant Staphylococcus aureus had the highest levels of resistance against penicillin (100), tetracycline (98.64), ampicillin (93.24) and oxacillin (93.24). The most commonly detected SCCmec types in the MRSA strains were type V (18.91) and III (17.56). Conclusions: Regular surveillance of hospital-associated infections and monitoring of the antibiotic sensitivity patterns are required to reduce the prevalence of MRSA. We recommend initial management of children affected by MRSA with imipenem, lincomycin and cephalothin prescriptions. © 2015, Ahvaz Jundishapur University of Medical Sciences

    Re-vision: the last chance to make it glow

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    У статті розглянуто прийоми редагування текстів, писаних англійською, задля покращання професійної комунікації у глобальному контексті за допомогою цієї мови. Увагу зосереджено на універсальних аспектах англомовного редагування, релевантних як для носіїв англійської, так і для тих, для кого вона не є рідною мовою, а саме: перефразування, скорочення, переміщення, а також ланцюжки еквівалентів, колокації, структурація за допомогою заголовків. Розглянутий матеріал рясно ілюстрований відповідними прикладами.В статье рассмотрены приемы редактирования англоязычных текстов с целью повышения эффективности профессиональной коммуникации на английском языке в глобальном контексте. Особое внимание уделяется универсальным аспектам англоязычного редактирования, релевантных как для носителей английского языка, так и для тех, для кого этот язык не является родным. Рассмотрены приемы перефразирования, сокращения, перемещения, а также цепочки эквивалентов, коллокации, структурирование при помощи заголовков. Материал статьи хорошо иллюстрирован соответствующими примерами.This paper presents the editing techniques that make professional writing more effective to help people develop their ability to communicate clearly and persuasively in English in its global context. It focuses specifically on those universal writing techniques that help the writers connect with other people whose first language may or may not be English. These include: paraphrasing, reduction and deletion, relocation, equivalency chains, collocations,and headings. The material is amply illustrated with relevant examples

    Anisotropic Inflation with Non-Abelian Gauge Kinetic Function

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    We study an anisotropic inflation model with a gauge kinetic function for a non-abelian gauge field. We find that, in contrast to abelian models, the anisotropy can be either a prolate or an oblate type, which could lead to a different prediction from abelian models for the statistical anisotropy in the power spectrum of cosmological fluctuations. During a reheating phase, we find chaotic behaviour of the non-abelian gauge field which is caused by the nonlinear self-coupling of the gauge field. We compute a Lyapunov exponent of the chaos which turns out to be uncorrelated with the anisotropy.Comment: 16 pages, 4 figure

    Hamilton-Jacobi Solutions for Strongly-Coupled Gravity and Matter

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    A Green's function method is developed for solving strongly-coupled gravity and matter in the semiclassical limit. In the strong-coupling limit, one assumes that Newton's constant approaches infinity. As a result, one may neglect second order spatial gradients, and each spatial point evolves like an homogeneous universe. After constructing the Green's function solution to the Hamiltonian constraint, the momentum constraint is solved using functional methods in conjunction with the superposition principle for Hamilton-Jacobi theory. Exact and approximate solutions are given for a dust field or a scalar field interacting with gravity.Comment: 26 pages Latex (IOP) file with 2 IOP style files, to be published in Classical and Quantum Gravity (1998

    Stabilization of the Yang-Mills chaos in non-Abelian Born-Infeld theory

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    We investigate dynamics of the homogeneous time-dependent SU(2) Yang-Mills fields governed by the non-Abelian Born-Infeld lagrangian which arises in superstring theory as a result of summation of all orders in the string slope parameter α\alpha'. It is shown that generically the Born-Infeld dynamics is less chaotic than that in the ordinary Yang-Mills theory, and at high enough field strength the Yang-Mills chaos is stabilized. More generally, a smothering effect of the string non-locality on behavior of classical fields is conjectured.Comment: 7 pages, 5 figure

    Axially Symmetric Bianchi I Yang-Mills Cosmology as a Dynamical System

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    We construct the most general form of axially symmetric SU(2)-Yang-Mills fields in Bianchi cosmologies. The dynamical evolution of axially symmetric YM fields in Bianchi I model is compared with the dynamical evolution of the electromagnetic field in Bianchi I and the fully isotropic YM field in Friedmann-Robertson-Walker cosmologies. The stochastic properties of axially symmetric Bianchi I-Einstein-Yang-Mills systems are compared with those of axially symmetric YM fields in flat space. After numerical computation of Liapunov exponents in synchronous (cosmological) time, it is shown that the Bianchi I-EYM system has milder stochastic properties than the corresponding flat YM system. The Liapunov exponent is non-vanishing in conformal time.Comment: 18 pages, 6 Postscript figures, uses amsmath,amssymb,epsfig,verbatim, to appear in CQ

    Validation of low-dose lung cancer PET-CT protocol and PET image improvement using machine learning

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    PURPOSE: To conduct a simplified lesion-detection task of a low-dose (LD) PET-CT protocol for frequent lung screening using 30% of the effective PETCT dose and to investigate the feasibility of increasing clinical value of low-statistics scans using machine learning. METHODS: We acquired 33 SD PET images, of which 13 had actual LD (ALD) PET, and simulated LD (SLD) PET images at seven different count levels from the SD PET scans. We employed image quality transfer (IQT), a machine learning algorithm that performs patch-regression to map parameters from low-quality to high-quality images. At each count level, patches extracted from 23 pairs of SD/SLD PET images were used to train three IQT models - global linear, single tree, and random forest regressions with cubic patch sizes of 3 and 5 voxels. The models were then used to estimate SD images from LD images at each count level for 10 unseen subjects. Lesion-detection task was carried out on matched lesion-present and lesion-absent images. RESULTS: LD PET-CT protocol yielded lesion detectability with sensitivity of 0.98 and specificity of 1. Random forest algorithm with cubic patch size of 5 allowed further 11.7% reduction in the effective PETCT dose without compromising lesion detectability, but underestimated SUV by 30%. CONCLUSION: LD PET-CT protocol was validated for lesion detection using ALD PET scans. Substantial image quality improvement or additional dose reduction while preserving clinical values can be achieved using machine learning methods though SUV quantification may be biased and adjustment of our research protocol is required for clinical use

    Chaos in the Einstein-Yang-Mills Equations

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    Yang-Mills color fields evolve chaotically in an anisotropically expanding universe. The chaotic behaviour differs from that found in anisotropic Mixmaster universes. The universe isotropizes at late times, approaching the mean expansion rate of a radiation-dominated universe. However, small chaotic oscillations of the shear and color stresses continue indefinitely. An invariant, coordinate-independent characterisation of the chaos is provided by means of fractal basin boundaries.Comment: 3 pages LaTeX + 3 pages of figure
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