2,146 research outputs found

    Searching for Charged Higgs Boson in Polarized Top Quark

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    The charged Higgs boson is quite common in many new physics models. In this study we examine the potential of observing a heavy charged Higgs boson in its decay mode of top-quark and bottom-quark in the Type-II Two-Higgs-Doublet-Model. In this model, the chirality structure of the coupling of charged Higgs boson to the top- and bottom-quark is very sensitive to the value of tanβ\tan\beta. As the polarization of the top-quark can be measured experimentally from the top-quark decay products, one could make use of the top-quark polarization to determine the value of tanβ\tan\beta. We preform a detailed analysis of measuring top-quark polarization in the production channels gbtHgb\to tH^- and gbˉtˉH+g\bar{b}\to \bar{t}H^+. We calculate the helicity amplitudes of the charged Higgs boson production and decay.Our calculation shows that the top-quark from the charged Higgs boson decay provides a good probe for measuring tanβ\tan\beta, especially for the intermediate tanβ\tan\beta region. On the contrary, the top-quark produced in association with the charged Higgs boson cannot be used to measure tanβ\tan\beta because its polarization is highly contaminated by the tt-channel kinematics.Comment: 21 pages, 12 figures, 2 table

    Substructuring Method in Structural Health Monitoring

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    In sensitivity-based finite element model updating, the eigensolutions and eigensensitivities are calculated repeatedly, which is a time-consuming process for large-scale structures. In this chapter, a forward substructuring method and an inverse substructuring method are proposed to fulfill the model updating of large-scale structures. In the forward substructuring method, the analytical FE model of the global structure is divided into several independent substructures. The eigensolutions of each independent substructure are used to recover the eigensolutions and eigensensitivities of the global structure. Consequently, only some specific substructures are reanalyzed in model updating and assembled with other untouched substructures to recover the eigensolutions and eigensensitivities of the global structure. In the inverse substructuring method, the experimental modal data of the global structure are disassembled into substructural flexibility. Afterwards, each substructure is treated as an independent structure to reproduce its flexibility through a model-updating process. Employing the substructuring method, the model updating of a substructure can be conducted by measuring the local area of the concerned substructure solely. Finally, application of the proposed methods to a laboratory tested frame structure reveals that the forward and inverse substructuring methods are effective in model updating and damage identification

    苦碟子联合低分子肝素钙治疗急性脑梗死疗效观察

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    Objective:  to evaluate combinative effect of Kudiezi Injection and low molecular weight heparin calcium in the treatment of acute cerebral infarction. Methods:  72 cases of acute cerebral infarction were randomly divided into two groups, the treatment group of 36 cases were treated with the combination of Kudiezi Injection and low molecular heparin calcium; the other 36 cases in the control group were treated with the combination of Xuesaitong injection and low molecular weight heparin calcium. The degree of neurological deficit score and clinical outcome were respectively evaluated before and after treatment. Results:  There are significant differences between the treatment group and the control group in results efficiency. Conclusion:  It can improve the curative effect and the prognosis of the patients in the acute stage of cerebral infarction in the combinative treatment of Kudiezi Injection and low molecular weight heparin.目的 评价苦碟子注射液联合低分子肝素钙治疗急性脑梗死的临床效果及护理方法。方法 将72例急性脑梗死患者随机分为两组,治疗组36例用苦碟子联合低分子肝素钙治疗;对照组36例用血塞通注射液联合低分子肝素钙治疗。治疗前后分别进行神经功能缺损程度评分以及临床疗效评定[5]。结果 治疗组显效率与对照组比较差异有非常显著性(P=0.009)。结论 对急性期脑梗死患者在常规治疗基础上加用苦碟子及低分子肝素钙可显著提高疗效,改善患者预后。

    Sound absorption properties of polyurethane-based warp-knitted spacer fabric composites

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    Sound absorption properties of polyurethane-based warp-knitted spacer fabric composites (PWSF) have been studied. The warp-knitted spacer fabrics (WSF) are produced on a double-needle bar warp knitting machine using different structural parameters including inclination angle of spacer yarn, thickness, spacer yarn’s diameter and surface layer structure. The composites are fabricated based on a flexible polyurethane foam. Accordingly, the acoustical behaviors of composites are evaluated properly by using two-microphone transfer function techniques in impedance tube. The findings reveal that the composites possess excellent sound absorption properties and their sound absorbability can be tailored to meet the specificend-use requirements by varying the fabric structural parameters

    Damage detection of shear connectors in bridge structures with transmissibility in frequency domain

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    Shear connectors are generally used to link the slab and girder together in slab-on-girder bridge structures. Damage of shear connectors in such structures will result in shear slippage between the slab and girder, which significantly reduces the load-carrying capacity of bridges. A damage detection approach based on transmissibility in frequency domain is proposed in this paper to identify the damage of shear connectors in slab-on-girder bridge structures with or without reference data from the undamaged structure. The transmissibility, which is an inherent system characteristic, indicates the relationship between two sets of response vectors in frequency domain. Measured input force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at the slab and girder sensor locations by the experimental modal analysis. The transmissibility matrix that relates the slab response to the girder response is then derived. By comparing the transmissibility vectors in undamaged and damaged states, the damage level of shear connectors can be identified. When the measurement data from the undamaged structure are not available, a study with only the measured response data in the damaged state for the condition assessment of shear connectors is also conducted. Numerical and experimental studies on damage detection of shear connectors linking a concrete slab to two steel girders are conducted to validate the accuracy and efficiency of the proposed approach. The results demonstrate that the proposed method can be used to identify shear connector damages accurately and efficiently. The proposed method is also applied to the condition evaluation of shear connectors in a real composite bridge with in-field testing data

    Geometric bionics: Lotus effect helps polystyrene nanotube films get good blood compatibility

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    Various biomaterials have been widely used for manufacturing biomedical applications including artificial organs, medical devices and disposable clinical apparatus, such as vascular prostheses, blood pumps, artificial kidney, artificial hearts, dialyzers and plasma separators, which could be used in contact with blood^1^. However, the research tasks of improving hemocompatibility of biomaterials have been carrying out with the development of biomedical requirements^2^. Since the interactions that lead to surface-induced thrombosis occurring at the blood-biomaterial interface become a reason of familiar current complications with grafts therapy, improvement of the blood compatibility of artificial polymer surfaces is, therefore a major issue in biomaterials science^3^. After decades of focused research, various approaches of modifying biomaterial surfaces through chemical or biochemical methods to improve their hemocompatibility were obtained^1^. In this article, we report that polystyrene nanotube films with morphology similar to the papilla on lotus leaf can be used as blood-contacted biomaterials by virtue of Lotus effect^4^. Clearly, this idea, resulting from geometric bionics that mimicking the structure design of lotus leaf, is very novel technique for preparation of hemocompatible biomaterials

    How tyramine β-hydroxylase controls the production of octopamine, modulating the mobility of beetles

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    Biogenic amines perform many kinds of important physiological functions in the central nervous system (CNS) of insects, acting as neuromodulators, neurotransmitters, and neurohormones. The five most abundant types of biogenic amines in invertebrates are dopamine, histamine, serotonin, tyramine, and octopamine (OA). However, in beetles, an important group of model and pest insects, the role of tyramine beta-hydroxylase (T beta H) in the OA biosynthesis pathway and the regulation of behavior remains unknown so far. We therefore investigated the molecular characterization and spatiotemporal expression profiles of T beta H in red flour beetles (Triboliun castaneum). Most importantly, we detected the production of OA and measured the crawling speed of beetles after dsTcT beta H injection. We concluded that TcT beta H controls the biosynthesis amount of OA in the CNS, and this in turn modulates the mobility of the beetles. Our new results provided basic information about the key genes in the OA biosynthesis pathway of the beetles, and expanded our knowledge on the physiological functions of OA in insects
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