2,653 research outputs found

    The quantum solvation, adiabatic versus nonadiabatic, and Markovian versus non-Markovian nature of electron transfer rate processes

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    In this work, we revisit the electron transfer rate theory, with particular interests in the distinct quantum solvation effect, and the characterizations of adiabatic/nonadiabatic and Markovian/non-Markovian rate processes. We first present a full account for the quantum solvation effect on the electron transfer in Debye solvents, addressed previously in J. Theore. & Comput. Chem. {\bf 5}, 685 (2006). Distinct reaction mechanisms, including the quantum solvation-induced transitions from barrier-crossing to tunneling, and from barrierless to quantum barrier-crossing rate processes, are shown in the fast modulation or low viscosity regime. This regime is also found in favor of nonadiabatic rate processes. We further propose to use Kubo's motional narrowing line shape function to describe the Markovian character of the reaction. It is found that a non-Markovian rate process is most likely to occur in a symmetric system in the fast modulation regime, where the electron transfer is dominant by tunneling due to the Fermi resonance.Comment: 13 pages, 10 figures, submitted to J. Phys. Chem.

    A novel hybrid finite element analysis of inplane singular elastic field around inclusion corners in elastic media

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    AbstractThis paper deals with the inplane singular elastic field problems of inclusion corners in elastic media by an ad hoc hybrid-stress finite element method. A one-dimensional finite element method-based eigenanalysis is first applied to determine the order of singularity and the angular dependence of the stress and displacement field, which reflects elastic behavior around an inclusion corner. These numerical eigensolutions are subsequently used to develop a super element that simulates the elastic behavior around the inclusion corner. The super element is finally incorporated with standard four-node hybrid-stress elements to constitute an ad hoc hybrid-stress finite element method for the analysis of local singular stress fields arising from inclusion corners. The singular stress field is expressed by generalized stress intensity factors defined at the inclusion corner. The ad hoc finite element method is used to investigate the problem of a single rectangular or diamond inclusion in isotropic materials under longitudinal tension. Comparison with available numerical results shows the present method is an efficient mesh reducer and yields accurate stress distribution in the near-field region. As applications, the present ad hoc finite element method is extended to discuss the inplane singular elastic field problems of a single rectangular or diamond inclusion in anisotropic materials and of two interacting rectangular inclusions in isotropic materials. In the numerical analysis, the generalized stress intensity factors at the inclusion corner are systematically calculated for various material type, stiffness ratio, shape and spacing position of one or two inclusions in a plate subjected to tension and shear loadings

    Changes In The Bargaining Power Of Chinese Migrant Workers And The Factors Enhancing Laborers Power

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    The shortage of migrant workers phenomenon is not only a reflection of the changing concept of occupation for Chinese migrant workers, but it also increases job opportunities for such workers. Migrant workers fight for higher wages through strikes and collective negotiations. These changes reflect the enhancement of the bargaining power of Chinese migrant workers.This paper explores the factors that enhance Chinese migrant workers bargaining power, uses a fuzzy comprehensive evaluation based on the analytic hierarchy process to assess the effect of various factors, and analyzes the positive and negative effects of enhancing the bargaining power. Finally, this paper predicts changes in the bargaining power of Chinese migrant workers and provides corresponding recommendations to protect their advantages

    Intervention study of finger-movement exercises and finger weight-lift training for improvement of handgrip strength among the very elderly

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    AbstractObjectivesTo examine the effects of finger-movement exercises and finger weight-lift training on handgrip strength and Activities of Daily Living Scale (ADLS) values.MethodsA total of 80 very elderly adults (aged ≥80 years) were assigned to either an intervention group (n = 40) or a control group (n = 40). Subjects in the intervention group performed finger-movement exercises and weight-lift training for a period of 3 months, while subjects in the control group received no intervention, and were unaware of the interventions received in the other group.ResultsAfter completing 3 months of finger-movement exercises and weight-lift training, the average handgrip strength of the 40 participants in the intervention group had increased by 2.1 kg, whereas that in the control group decreased by 0.27 kg (P < 0.05). After receiving intervention, the number of subjects in the intervention group with an ADLS score >22 points decreased by 7.5% (P < 0.05, vs. pre-intervention).ConclusionsThe combined use intervention with finger-movement exercises and proper finger weight-lift training improved the handgrip strength and ADLS values of very elderly individuals. These rehabilitation exercises may be used to help the elderly maintain their self-care abilities

    Taxonomic studies on the subtribe Aphrastobraconina Ashmead (Hymenoptera: Braconidae: Braconinae) in China

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    The species of the subtribe Aphrastobraconina Ashmead from China were studied and five species belonging to three genera (Undabracon Quicke, 1986, Curriea Ashmead, 1900 and Aphrastobracon Ashmead, 1896) recognized. Three new species (Undabracon cariniventris sp. n., Aphrastobracon huanjiangensis sp. n. and A. politus sp. n.) are fully described and illustrated. The genus Undabracon (Quicke, 1986), the species Aphrastobracon flavipennis Ashmead and Curriea tibialis (Ashmead) are reported for the first time from China. A key to the species of the genus Undabracon is provided
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