30,023 research outputs found

    On the inverse Compton scattering model of radio pulsars

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    Some characteristics of the inverse Compton scattering (ICS) model are reviewed. At least the following properties of radio pulsars can be reproduced in the model: core or central emission beam, one or two hollow emission cones, different emission heights of these components, diverse pulse profiles at various frequencies, linear and circular polarization features of core and cones.Comment: 5 pages, no figures, LaTeX, a proceeding paper for Pacific Rim Conference on Stellar Astrophysics, Aug. 1999, HongKong, Chin

    Exponential stabilization of laminated beams with structural damping and boundary feedback controls

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    We study the boundary stabilization of laminated beams with structural damping which describes the slip occurring at the interface of two-layered objects. By using an invertible matrix function with an eigenvalue parameter and an asymptotic technique for the first order matrix differential equation, we find out an explicit asymptotic formula for the matrix fundamental solutions and then carry out the asymptotic analyses for the eigenpairs. Furthermore, we prove that there is a sequence of generalized eigenfunctions that forms a Riesz basis in the state Hilbert space, and hence the spectrum determined growth condition holds. Furthermore, exponential stability of the closed-loop system can be deduced from the eigenvalue expressions. In particular, the semigroup generated by the system operator is a Co-group due to the fact that the three asymptotes of the spectrum are parallel to the imaginary axis. © 2005 Society for Industrial and Applied Mathematics.published_or_final_versio

    Exponential stability of variable coefficients Rayleigh beams under boundary feedback controls: A Riesz basis approach

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    In this paper, we study the boundary stabilizing feedback control problem of Rayleigh beams that have non-homogeneous spatial parameters. We show that no matter how non-homogeneous the Rayleigh beam is, as long as it has positive mass density, stiffness and mass moment of inertia, it can always be exponentially stabilized when the control parameters are properly chosen. The main steps are a detail asymptotic analysis of the spectrum of the system and the proving of that the generalized eigenfunctions of the feedback control system form a Riesz basis in the state Hilbert space. As a by-product, a conjecture in Guo (J. Optim. Theory Appl. 112(3) (2002) 529) is answered. © 2003 Elsevier B.V. All rights reserved.postprin

    The development and validation of questionnaire to assess the collaboration and teamwork between doctors and nurses in public hospital in China

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    This study reports the development and psychometric properties of a Chinese in-strument to assess doctor-nurse teamwork and collaboration. 398 doctors and nurses participated in the study. Feedback from experts with international medical or nursing background and doctors and nurses working in hospitals in China informed the questionnaire refinement. Through validity and reliability test, a 26-item questionnaire was developed. Three were identified. The overall questionnaire as well as each factor had high construct validity. The internal consistency reliabil-ity and test-retest reliability are also satis-factory.published_or_final_versio

    Teamwork and collaboration among doctors and nurses in two public hospitals in China

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    The Work-related Collaboration among Doctor-Nurse Scale (WCDNS) was ad-ministered to 398 doctors and nurses working in one of two hospitals in Guangzhou to assess 1) inter professional (doctor-nurse) differences in collaboration and teamwork and 2) inter hospital (general-specialist) differences in doctor nurse collaboration. Significant between profession and hospital differences were observed. Implications for future studies in doctor-nurse collaboration are discussed.published_or_final_versio

    Cycling of Rational Hybridization Chain Reaction To Enable Enzyme-Free DNA-Based Clinical Diagnosis

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    In order to combat the growing threat of global infectious diseases, there is a need for rapid diagnostic technologies that are sensitive and that can provide species specific information (as might be needed to direct therapy as resistant strains of microbes emerge). Here, we present a convenient, enzyme-free amplification mechanism for a rational hybridization chain reaction, which is implemented in a simple format for isothermal amplification and sensing, applied to the DNA-based diagnosis of hepatitis B virus (HBV) in 54 patients. During the cycled amplification process, DNA monomers selfassemble in an organized and controllable way only when a specific target HBV sequence is present. This mechanism is confirmed using super-resolution stochastic optical reconstruction microscopy. The enabled format is designed in a manner analogous to an enzyme-linked immunosorbent assay, generating colored products with distinct tonality and with a limit of detection of ca. five copies/reaction. This routine assay also showed excellent sensitivity (>97%) in clinical samples demonstrating the potential of this convenient, low cost, enzyme-free method for use in low resource settings

    Spinor Helicity and Dual Conformal Symmetry in Ten Dimensions

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    The spinor helicity formalism in four dimensions has become a very useful tool both for understanding the structure of amplitudes and also for practical numerical computation of amplitudes. Recently, there has been some discussion of an extension of this formalism to higher dimensions. We describe a particular implementation of the spinor-helicity method in ten dimensions. Using this tool, we study the tree-level S-matrix of ten dimensional super Yang-Mills theory, and prove that the theory enjoys a dual conformal symmetry. Implications for four-dimensional computations are discussed.Comment: 24 pages, 1 figure
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